ALBERT

Description: We report the discovery of a new group of double-periodic RR Lyrae stars from the analysis of the Optical Gravitational Lensing Experiment - IV (OGLE-IV) Galactic bulge photometry. In 11 stars identified in the OGLE catalogue as first overtone pulsators (RRc stars), we detect additional longer period variability of low amplitude, in the mmag regime. One additional star of the same type is identified in a published analysis of the Kepler space photometry. The period ratio between the shorter first overtone period and a new, longer period lies in a narrow range around 0.686. Thus, the additional period is longer than the expected period of the undetected radial fundamental mode. The obvious conclusion that addition periodicity corresponds to a gravity or a mixed mode faces difficulties, however.

Description: We investigate the recent claim of ‘photon underproduction crisis’ by Kollmeier et al. which suggests that the known sources of ultraviolet (UV) radiation may not be sufficient to generate the inferred H i photoionization rate ( $\Gamma _{\rm H\,\small {i}}$ ) in the low-redshift intergalactic medium. Using the updated QSO emissivities from the recent studies and our cosmological radiative transfer code developed to estimate the UV background, we show that the QSO contributions to $\Gamma _{\rm H\,\small {i}}$ is higher by a factor ~2 as compared to the previous estimates. Using self-consistently computed combinations of star formation rate density and dust attenuation, we show that a typical UV escape fraction of 4 per cent from star-forming galaxies should be sufficient to explain the inferred $\Gamma _{\rm H\,\small {i}}$ by Kollmeier et al. Interestingly, we find that the contribution from QSOs alone can explain the recently inferred $\Gamma _{\rm H\,\small {i}}$ by Shull et al. which used the same observational data but different simulation. Therefore, we conclude that the crisis is not as severe as it was perceived before and there seems no need to look for alternate explanations such as low luminosity hidden QSOs or decaying dark matter particles.

Description: Dusty, star-forming galaxies have a critical role in the formation and evolution of massive galaxies in the Universe. Using deep far-infrared imaging in the range 100–500 μm obtained with the Herschel telescope, we investigate the dust-obscured star formation (SF) in the galaxy cluster XDCP J0044.0-2033 at z  = 1.58, the most massive cluster at z  〉 1.5, with a measured mass M 200  = 4.7 $^{+1.4}_{-0.9}$  10 14  M . We perform an analysis of the spectral energy distributions (SEDs) of 12 cluster members (5 spectroscopically confirmed) detected with ≥3 significance in the PACS maps, all ultraluminous infrared galaxies. The individual star formation rates (SFRs) lie in the range 155–824 M yr –1 , with dust temperatures of 24–35 K. We measure a strikingly high amount of SF in the cluster core, SFR (〈250 kpc) ≥ 1875 ± 158 M yr –1 , four times higher than the amount of SF in the cluster outskirts. This scenario is unprecedented in a galaxy cluster, showing for the first time a reversal of the SF–density relation at z ~ 1.6 in a massive cluster.

Description: In this Letter, we investigate the role of recombination energy during a common envelope event. We confirm that taking this energy into account helps to avoid the formation of the circumbinary envelope commonly found in previous studies. For the first time, we can model a complete common envelope event, with a clean compact double white dwarf binary system formed at the end. The resulting binary orbit is almost perfectly circular. In addition to considering recombination energy, we also show that between 1/4 and 1/2 of the released orbital energy is taken away by the ejected material. We apply this new method to the case of the double white dwarf system WD 1101+364, and we find that the progenitor system at the start of the common envelope event consisted of an ~1.5 M red giant star in an ~30 d orbit with a white dwarf companion.

Description: Aberrant glycosylation is highly associated with cancer progression. The aim of this study was to compare bifucosylated N -glycans in sera obtained from healthy controls and breast cancer patients, with the goal of identifying a potential indicator for monitoring the recurrence and metastasis of breast cancer. A unique structural pattern of bifucosylated N -glycan, with both core and antennary fucosylation, was identified in breast cancer patients. The spectrum of antennary fucosylation was a composite of the standard spectra of Lewis X and H2, indicating a mixture of the two epitopes. Permethylated N -glycans of the glycoproteins extracted from 91 breast cancer patients and 43 healthy controls were detected using linear ion-trap quadrupole-electrospray ionization mass spectrometry, which appeared to be a highly sensitive and useful approach in the detection and identification of N -glycans. To evaluate MS profile data, several statistical tools were applied, including Student's t -test, partial least squares discriminant analysis and receiver-operating characteristic curve. The results showed that the measurement of bifucosylation degree and CEA levels had an improved diagnostic performance compared with that of CEA alone. We compared the potential of bifucosylated N -glycan as an indicator of breast cancer recurrence with the current clinical biomarkers, i.e., CEA, CA 15-3 and CA125. The result revealed that, compared with CEA, CA 15-3 and CA125, the bifucosylation degree of N -glycans could be a more reliable indicator of breast cancer recurrence.

Description: Colitose, also known as 3,6-dideoxy- l -galactose or 3-deoxy- l -fucose, is one of only five naturally occurring 3,6-dideoxyhexoses. Colitose was found in lipopolysaccharide of a number of infectious bacteria, including Escherichia coli O55 & O111 and Vibrio cholera O22 & O139. To date, no colitosyltransferase (ColT) has been characterized, probably due to the inaccessibility of the sugar donor, GDP-colitose. In this study, starting with chemically prepared colitose, 94.6 mg of GDP-colitose was prepared via a facile and efficient one-pot two-enzyme system involving an l -fucokinase/GDP- l -Fuc pyrophosphorylase and an inorganic pyrophosphatase (EcPpA). WbgN, a putative ColT from E. coli O55:H5 was then cloned, overexpressed, purified and biochemically characterized by using GDP-colitose as a sugar donor. Activity assay and structural identification of the synthetic product clearly demonstrated that wbgN encodes an α1,2-ColT. Biophysical study showed that WbgN does not require metal ion, and is highly active at pH 7.5–9.0. In addition, acceptor specificity study indicated that WbgN exclusively recognizes lacto- N -biose (Galβ1,3-GlcNAc). Most interestingly, it was found that WbgN exhibits similar activity toward GDP- l -Fuc ( k cat / K m = 9.2 min –1 mM –1 ) as that toward GDP-colitose ( k cat / K m = 12 min –1 mM –1 ). Finally, taking advantage of this, type 1 H-antigen was successfully synthesized in preparative scale.

Description: Information about specificity and affinity is critical for use of carbohydrate-binding antibodies. Herein, we evaluated eight monoclonal antibodies to the blood group A (BG-A) antigen. Antibodies 87-G, 9A, HE-10, HE-24, HE-193, HE-195, T36 and Z2A were profiled on a glycan microarray to assess specificity, relative affinity and the influence of glycan density on recognition. Our studies highlight several noteworthy recognition properties. First, most antibodies bound GalNAcα1–3Gal and the BG-A trisaccharide nearly as well as larger BG-A oligosaccharides. Second, several antibodies only bound the BG-A trisaccharide when displayed on certain glycan chains. These first two points indicate that the carrier glycan chains primarily influence selectivity, rather than binding strength. Third, binding of some antibodies was highly dependent on glycan density, illustrating the importance of glycan presentation for recognition. Fourth, some antibodies recognized the tumor-associated Tn antigen, and one antibody only bound the variant composed of a GalNAc-alpha-linked to a serine residue. Collectively, these results provide new insights into the recognition properties of anti-BG-A antibodies.

Description: The abundance of O in planetary nebulae (PNe) has been historically used as a metallicity indicator of the interstellar medium (ISM), where they originated; e.g. it has been widely used to study metallicity gradients in our Galaxy and beyond. However, clear observational evidence for O self-enrichment in low-metallicity Galactic PNe with C-rich dust has been recently reported. Here, we report asymptotic giant branch (AGB) nucleosynthesis predictions for the abundances of the CNO elements and helium in the metallicity range Z /4 〈 Z 〈 2 Z . Our AGB models, with diffusive overshooting from all the convective borders, predict that O is overproduced in low- Z low-mass (~1–3 M ) AGB stars and nicely reproduce the recent O overabundances observed in C-rich dust PNe. This confirms that O is not always a good proxy of the original ISM metallicity and other chemical elements such as Cl or Ar should be used instead. The production of oxygen by low-mass stars should be thus considered in galactic-evolution models.

Description: Popular models of fast radio bursts (FRBs) involve the gravitational collapse of neutron star progenitors to black holes. It has been proposed that the shedding of the strong neutron star magnetic field ( B ) during the collapse is the power source for the radio emission. Previously, these models have utilized the simplicity of the Schwarzschild metric which has the restriction that the magnetic flux is magnetic ‘hair’ that must be shed before final collapse. But neutron stars have angular momentum and charge and a fully relativistic Kerr–Newman solution exists in which B has its source inside of the event horizon. In this Letter, we consider the magnetic flux to be shed as a consequence of the electric discharge of a metastable collapsed state of a Kerr–Newman black hole. It has also been argued that the shedding model will not operate due to pair creation. By considering the pulsar death line, we find that for a neutron star with B  = 10 11 –10 13  G and a long rotation period, 〉1s this is not a concern. We also discuss the observational evidence supporting the plausibility of magnetic flux shedding models of FRBs that are spawned from rapidly rotating progenitors.

Description: The mass discrepancy acceleration relation (MDAR) describes the coupling between baryons and dark matter (DM) in galaxies: the ratio of total-to-baryonic mass at a given radius anticorrelates with the acceleration due to baryons. The MDAR has been seen as a challenge to the cold dark matter (CDM) galaxy formation model, while it can be explained by Modified Newtonian Dynamics. In this Letter, we show that the MDAR arises in a CDM cosmology once observed galaxy scaling relations are taken into account. We build semi-empirical models based on CDM haloes, with and without the inclusion of baryonic effects, coupled to empirically motivated structural relations. Our models can reproduce the MDAR: specifically, a mass-dependent density profile for DM haloes can fully account for the observed MDAR shape, while a universal profile shows a discrepancy with the MDAR of dwarf galaxies with M *  〈 10 9.5  M , a further indication suggesting the existence of DM cores. Additionally, we reproduce slope and normalization of the baryonic Tully–Fisher relation (BTFR) with 0.17 dex scatter. These results imply that in CDM (i) the MDAR is driven by structural scaling relations of galaxies and DM density profile shapes, and (ii) the baryonic fractions determined by the BTFR are consistent with those inferred from abundance-matching studies.

Description: When inferring parameters from a Gaussian-distributed data set by computing a likelihood, a covariance matrix is needed that describes the data errors and their correlations. If the covariance matrix is not known a priori, it may be estimated and thereby becomes a random object with some intrinsic uncertainty itself. We show how to infer parameters in the presence of such an estimated covariance matrix, by marginalizing over the true covariance matrix, conditioned on its estimated value. This leads to a likelihood function that is no longer Gaussian, but rather an adapted version of a multivariate t -distribution, which has the same numerical complexity as the multivariate Gaussian. As expected, marginalization over the true covariance matrix improves inference when compared with Hartlap et al.'s method, which uses an unbiased estimate of the inverse covariance matrix but still assumes that the likelihood is Gaussian.

Description: Based on general polytropic (GP) magnetohydrodynamics (MHD), we offer a self-similar dynamic formalism for a magnetized, infinitely long, axially uniform cylinder of axisymmetry under self-gravity with radial and axial flows and with helical magnetic field. We identify two major classes of solution domains and obtain a few valuable MHD integrals in general. We focus on one class that has the freedom of prescribing a GP dynamic equation of state including the isothermal limit and derive analytic asymptotic solutions for illustration. In particular, we re-visit the isothermal MHD problem of Tilley & Pudritz (TP) and find that TP's main conclusion regarding the MHD solution behaviour for a strong ring magnetic field of constant toroidal flux-to-mass ratio to be incorrect. As this is important for conceptual scenarios, MHD cylinder models, testing numerical codes and potential observational diagnostics of magnetized filaments in various astrophysical contexts, we show comprehensive theoretical analysis and reasons as well as extensive numerical results to clarify pertinent points in this Letter. In short, for any given value be it small or large, the asymptotic radial scaling of the reduced mass density α( x ) at sufficiently large x should always be ~ x –4 instead of ~ x –2 contrary to the major claim of TP.

Description: During malignant transformation, glycosylation is heavily altered compared with healthy tissue due to differential expression of glycosyltransferases, glycosidases and monosaccharide transporters within the cancer microenvironment. One key change of malignant tissue glycosylation is the alteration of sialic acid processing that leads to a general upregulation of sialylated glycans (hypersialylation) on cell surfaces and an increased introduction of the non-human sialic acid N -glycolyl-neuraminic acid (Neu5Gc) instead of N -acetyl-neuraminic acid into cell surface glycans. These changes have been shown to be the result of altered sialyltransferase and sialidase expression. Functionally, cancer-associated hypersialylation appears to directly impact tumor cell interaction with the microenvironment, in particular the modulation of sialic acid-binding lectins on immune cells. Moreover, Neu5Gc expression in human tissues enhances inflammation due to an anti-Neu5Gc immune response, which can potentially influence inflammation-induced cancer and cancer-associated inflammation. In this review, we summarize the changes of sialic acid biology within the malignant microenvironment and the resulting effect on cancer immunity.

Description: In this work, we present the first XOS degrading glycoside hydrolase from Weissella , W Xyn43, a two-domain enzyme from GH43. The gene was amplified from genomic DNA of the XOS utilizing Weissella strain 92, classified under the species-pair Weissella cibaria/W.confusa , and expressed in Escherichia coli . The enzyme is lacking a putative signal peptide and is, from a homology model, shown to be composed of an N-terminal 5-fold β-propeller catalytic domain and a C-terminal β-sandwich domain of unknown function. W Xyn43 hydrolyzed short (1–4)-β- d -xylooligosaccharides, with similar k cat / K M for xylobiose (X 2 ) and xylotriose (X 3 ) and clearly lower efficiency in xylotetraose (X 4 ) conversion. WXyn43 displays the highest reported k cat for conversion of X 3 (900 s –1 at 37°C) and X 4 (770 s –1 ), and k cat for hydrolysis of X 2 (907 s –1 ) is comparable with or greater than the highest previously reported. The purified enzyme adopted a homotetrameric state in solution, while a truncated form with isolated N-terminal catalytic domain adopted a mixture of oligomeric states and lacked detectable activity. The homology model shows that residues from both domains are involved in monomer–monomer hydrogen bonds, while the bonds creating dimer–dimer interactions only involved residues from the N-terminal domain. Docking of X 2 and X 3 in the active site shows interactions corresponding to subsites –1 and +1, while presence of a third subsite is unclear, but interactions between a loop and the reducing-end xylose of X 3 may be present.

Description: The acquisition of mannose 6-phosphate (Man6 P ) on N-linked glycans of lysosomal enzymes is a structural requirement for their transport from the Golgi apparatus to lysosomes mediated by the mannose 6-phosphate receptors, 300 kDa cation-independent mannose 6-phosphate receptor (MPR300) and 46 kDa cation-dependent mannose 6-phosphate receptor (MPR46). Here we report that the single-chain variable domain (scFv) M6P-1 is a unique antibody fragment with specificity for Man6 P monosaccharide that, through an array-screening approach against a number of phosphorylated N -glycans, is shown to bind mono- and diphosphorylated Man 6 and Man 7 glycans that contain terminal αMan6 P (1 -〉 2)αMan(1 -〉 3)αMan. In contrast to MPR300, scFv M6P-1 does not bind phosphodiesters, monophosphorylated Man 8 or mono- or diphosphorylated Man 9 structures. Single crystal X-ray diffraction analysis to 2.7 Å resolution of Fv M6P-1 in complex with Man6 P reveals that specificity and affinity is achieved via multiple hydrogen bonds to the mannose ring and two salt bridges to the phosphate moiety. In common with both MPRs, loss of binding was observed for scFv M6P-1 at pH values below the second p K a of Man6 P (p K a = 6.1). The structures of Fv M6P-1 and the MPRs suggest that the change of the ionization state of Man6 P is the main driving force for the loss of binding at acidic lysosomal pH (e.g. lysosome pH ~ 4.6), which provides justification for the evolution of a lysosomal enzyme transport pathway based on Man6 P recognition.

Description: There is growing observational evidence of high-redshift quasars launching energetic, fast outflows, but the effects that these have on their host galaxies is poorly understood. We employ the moving-mesh code AREPO to study the feedback from a quasar that has grown to ~10 9 M by z  ~ 5 and the impact that this has on its host galaxy. Our simulations use a super-Lagrangian refinement technique to increase the accuracy with which the interface of the quasar-driven wind and the surrounding gas is resolved. We find that the feedback injected in these simulations is less efficient at removing gas from the galaxy than in an identical simulation with no super-Lagrangian refinement. This leads to the growth of a massive, rotationally supported, star-forming disc, co-existing with a powerful quasar-driven outflow. The properties of our host galaxy, including the kinematical structure of the gaseous disc and of the outflow, are in good agreement with current observations. Upcoming ALMA and JWST observations will be an excellent test of our model and will provide further clues as to the variance in properties of high-redshift quasar hosts.

Description: The first stars, known as Population III (PopIII), produced the first heavy elements, thereby enriching their surrounding pristine gas. Previous detections of metals in intergalactic gas clouds, however, find a heavy element enrichment larger than 1/1000 times that of the solar environment, higher than expected for PopIII remnants. In this letter, we report the discovery of a Lyman limit system (LLS) at z  = 3.53 with the lowest metallicity seen in gas with discernable metals, 10 –3.41±0.26 times the solar value, at a level expected for PopIII remnants. We make the first relative abundance measurement in such low metallicity gas: the carbon-to-silicon ratio is 10 –0.26±0.17 times the solar value. This is consistent with models of gas enrichment by a PopIII star formation event early in the Universe, but also consistent with later, Population II enrichment. The metals in all three components comprising the LLS, which has a velocity width of 400 km s –1 , are offset in velocity by ~+6 km s –1 from the bulk of the hydrogen, suggesting the LLS was enriched by a single event. Relative abundance measurements in this near-pristine regime open a new avenue for testing models of early gas enrichment and metal mixing.

Description: We report on the results of XMM–Newton and Swift observations of SMC X-2 during its last outburst in 2015 October, the first one since 2000. The source reached a very high luminosity ( L ~ 10 38 erg s –1 ), which allowed us to perform a detailed analysis of its timing and spectral properties. We obtained a pulse period P spin = 2.372267(5) s and a characterization of the pulse profile also at low energies. The main spectral component is a hard ( ~= 0) power-law model with an exponential cut-off, but at low energies we detected also a soft (with kT ~= 0.15 keV) thermal component. Several emission lines are present in the spectrum. Their identification with the transition lines of highly ionized N, O, Ne, Si, and Fe suggests the presence of photoionized matter around the accreting source.

Description: The role of aberrant protein modifications in cancer and its diagnosis have emerged as a promising research field. Nonenzymatic glyco-oxidation of proteins under oxidative stress has been associated with carcinogenesis through advanced glycation end products (AGE)–receptors for advanced glycation end products (RAGE) axis. Modified proteins that are immunogenic and stimulate cellular and humoral immune responses are being studied to develop early detection markers of cancer. This study has probed the structural alternations; leading to the formation of adducts and aggregates, in histone H2A upon in vitro modification by methylglyoxal (MG). The immunogenicity of modified histone H2A and its binding with cancer autoantibodies was also assessed. MG induced lysine side chain modifications, blocking of free amino groups and the formation of condensed cross structures in histone H2A; and its effect was inhibited by carbonyl scavengers. It led to the adduct formation and generation of N -epsilon-(carboxyethyl)lysine (CEL) and its decomposition forms as revealed by Matrix-assisted laser desorption ionization–mass spectrometry, high-performance liquid chromatography and LC–MS. MG-H2A showed amorphous aggregate formation under electron microscopy and altered binding with DNA in circular dichroism studies. The modified histone elicited high titer immunogen-specific antibodies in rabbits when compared with the native, thus pointing toward the generation of neo-epitopes in MG-H2A. The autoantibodies derived from cancer patients exhibited enhanced binding with MG-H2A as compared with the native histone in enzyme-linked immunosorbent assay and gel retardation assay. This reflects sharing of epitopes on MG-H2A and histones in cancer patients. The neo-epitopes on H2A may be responsible for induction and elevated levels of antibodies in cancer patients. Thus, MG-H2A may be considered as potential antigenic candidate for auto-immune response in cancer.

Description: E-cadherin is often dysregulated in aggressive lung cancer, the mechanism of which cannot always be explained at the level of transcription. In 66 patients with lung cancer, immunohistochemical staining demonstrated that co-localization of E-cadherin and core fucose by Lens culinaris agglutinin was significantly less extensive in tumor than in nontumor tissue. Through gain and loss of fucosylation experiments in the giant lung carcinoma cell lines 95C and 95D, our results revealed that E-cadherin core fucosylation in 95C cells overexpressing α-1, 6-fucosyltransferase (Fut8) inhibited Fut8-95C cell migration, whereas knockdown of Fut8 in 95D cells enhanced migration of short-interfering RNA-targeting Fut8 (siFut8)-95D cells. The level of active Src (phosphorylated Src [Y416]) was significantly reduced in Fut8-95C cells, but elevated in siFut8-95D cells. In protein complexes immunoprecipitated from Fut8-95C cell lysates with anti-E-cadherin, less phosphorylated Src (Y416) and more β-catenin were observed, but immunoprecipitates from siFut8-95D cells, containing less core fucosylated E-cadherin, contained an elevated level of phospho-Src Y416. In Fut8-95C cells, phosphorylation of Akt (Y315, Y326) and GSK-3β (S9) was significantly reduced, but β-catenin (S37) phosphorylation was enhanced. Expression of N-cadherin and Snail1 was also reduced in Fut8-95C cells, but significantly increased in siFut8-95D cells. Intriguingly, when Src kinase activity was inhibited by treatment of cells with PP2 and SU6656, regulation of N-cadherin, Snail1 and cell migration by E-cadherin core fucosylation was abrogated in both Fut8-95C and siFut8-95D cells. Therefore, posttranslational modification of E-cadherin by less core fucosylation recruited and activated Src, and induced an epithelial–mesenchymal transition-like process in lung cancer cells.

Description: Statins, which specifically inhibit HMG Co-A reductase, the rate-limiting step of cholesterol biosynthesis, are widely prescribed to reduce serum cholesterol and cardiac risk, but many other effects are seen. We now show an effect of these drugs to induce profound changes in the step-wise synthesis of glycosphingolipids (GSLs) in the Golgi. Glucosylceramide (GlcCer) was increased several-fold in all cell lines tested, demonstrating a widespread effect. Additionally, de novo or elevated lactotriaosylceramide (Lc3Cer; GlcNAcβ1-3Galβ1-4GlcCer) synthesis was observed in 70%. Western blot showed that GlcCer synthase (GCS) was elevated by statins, and GCS and Lc3Cer synthase (Lc3S) activities were increased; however, transcript was elevated for Lc3S only. Supplementation with the isoprenoid precursor, geranylgeranyl pyrophosphate (GGPP), a downstream product of HMG Co-A reductase, reversed statin-induced glycosyltransferase and GSL elevation. The Rab geranylgeranyl transferase inhibitor 3-PEHPC, but not specific inhibitors of farnesyl transferase, or geranylgeranyl transferase I, was sufficient to replicate statin-induced GlcCer and Lc3Cer synthesis, supporting a Rab prenylation-dependent mechanism. While total cholesterol was unaffected, the trans-Golgi network (TGN) cholesterol pool was dissipated and medial Golgi GCS partially relocated by statins. GSL-dependent vesicular retrograde transport of Verotoxin and cholera toxin to the Golgi/endoplasmic reticulum were blocked after statin or 3-PEHPC treatment, suggesting aberrant, prenylation-dependent vesicular traffic as a basis of glycosyltransferase increase and GSL remodeling. These in vitro studies indicate a previously unreported link between Rab prenylation and regulation of GCS activity and GlcCer metabolism.

Description: Galectin-3 is a ubiquitous lectin exerting multiple cellular functions such as RNA splicing, protein trafficking and apoptosis. Its expression is positively correlated with the poor prognosis in lung cancer patients. Galectin-3 can promote cancer progression through its effects on cell proliferation, cell survival or cancer metastasis. However, the role of galectin-3 in the regulation of cancer stem-like cells (CSCs) is still unclear. Here, we investigated the hypothesis that galectin-3 might regulate lung CSCs via the EGF receptor (EGFR) signaling pathway. In our study, galectin-3 facilitated EGFR activation and enhanced the sphere formation activity of lung cancer cells. Furthermore, galectin-3 promoted Sox2 expression in an EGFR activation-dependent manner; importantly, forced expression of Sox2 blunted the effect of galectin-3 knockdown on lung cancer sphere formation ability. These results suggest that galectin-3 promotes EGFR activation leading to the upregulation of Sox2 expression and lung CSCs properties. Moreover, we showed that the carbohydrate-binding activity of galectin-3 was important for the regulation of EGFR activation, Sox2 expression and sphere formation. We have recently reported that c-Myc is a transcriptional activator of Sox2. We further found that galectin-3 enhanced c-Myc protein stability leading to increased c-Myc binding to the Sox2 gene promoter. We also examined the effect of the stemness factors, Oct4, Nanog and Sox2 on the expression of galectin-3. We found that Oct4 enhanced galectin-3 expression. Our results together suggest that galectin-3 enhances lung cancer stemness through the EGFR/c-Myc/Sox2 axis; Oct4, in turn, promotes galectin-3 expression, forming a positive regulatory loop in lung CSCs.

Description: β-1,2-Linked mannosides are expressed on numerous cell-wall glycoconjugates of the opportunistic pathogen yeast Candida albicans . Several studies evidenced their implication in the host–pathogen interaction and virulence mechanisms. In the present study, we characterized the in vitro activity of CaBmt3, a β-1,2-mannosyltransferase involved in the elongation of β-1,2-oligomannosides oligomers onto the cell-wall polymannosylated N -glycans. A recombinant soluble enzyme Bmt3p was produced in Pichia pastoris and its enzyme activity was investigated using natural and synthetic oligomannosides as potential acceptor substrates. Bmt3p was shown to exhibit an exquisite enzymatic specificity by adding a single terminal β-mannosyl residue to α-1,2-linked oligomannosides capped by a Manβ1–2Man motif. Furthermore, we demonstrated that the previously identified CaBmt1 and CaBmt3 efficiently act together to generate Manβ1-2Manβ1–2[Manα1–2] n sequence from α-1,2-linked oligomannosides onto exogenous and endogenous substrates.

Description: The local properties of turbulence driven by the magnetorotational instability (MRI) in rotating, shearing flows are studied in the framework of a shearing-box model. Based on numerical simulations, we propose that the MRI-driven turbulence comprises two components: the large-scale shear-aligned strong magnetic field and the small-scale fluctuations resembling magnetohydrodynamic (MHD) turbulence. The energy spectrum of the large-scale component is close to k –2 , whereas the spectrum of the small-scale component agrees with the spectrum of strong MHD turbulence k –3/2 . While the spectrum of the fluctuations is universal, the outer-scale characteristics of the turbulence are not; they depend on the parameters of the system, such as the net magnetic flux. However, there is remarkable universality among the allowed turbulent states – their intensity v 0 and their outer scale 0 satisfy the balance condition v 0 / 0 ~ d/dln r , where d/dln r is the local orbital shearing rate of the flow. Finally, we find no sustained dynamo action in the Pm = 1 zero net-flux case for Reynolds numbers as high as 45 000, casting doubts on the existence of an MRI dynamo in the Pm ≤ 1 regime.

Description: We present joint NuSTAR and XMM–Newton observations of the bright, variable quasar IRAS 13349+2438. This combined data set shows two clear iron absorption lines at 8 and 9 keV, which are most likely associated with two layers of mildly relativistic blueshifted absorption, with velocities of ∼0.14c and ∼0.27c. We also find strong evidence for a series of Ly α absorption lines at intermediate energies in a stacked XMM–Newton EPIC-pn spectrum, at the same blueshift as the lower velocity iron feature. This is consistent with a scenario where an outflowing wind is radially stratified, so faster, higher ionization material is observed closer to the black hole, and cooler, slower material is seen from streamlines at larger radii.

Description: We study the impact of a small-scale dynamo in core-collapse supernovae using a 3D neutrino magnetohydrodynamics (MHD) simulation of a 15 M⊙ progenitor. The weak seed field is amplified exponentially in the gain region once neutrino-driven convection develops, and remains dominated by small-scale structures. About $250, mathrm{ms}$ after bounce, the field energy in the gain region reaches ${sim } 50{{ m per cent}}$ of kinetic equipartition. This supports the development of a neutrino-driven explosion with modest global anisotropy, which does not occur in a corresponding model without magnetic fields. Our results suggest that magnetic fields may play a beneficial subsidiary role in neutrino-driven supernovae even without rapid progenitor rotation. Further investigation into the nature of MHD turbulence in the supernova core is required.

Description: We report on simultaneous observations of the magnetar SGR J1745–2900 at frequencies = 2.54–225 GHz using the Nançay 94-m equivalent, Effelsberg 100-m, and IRAM 30-m radio telescopes. We detect SGR J1745–2900 up to 225 GHz, the highest radio frequency detection of pulsed emission from a neutron star to date. Strong single pulses are also observed from 4.85 up to 154 GHz. At the millimetre band we see significant flux density and spectral index variabilities on time scales of tens of minutes, plus variability between days at all frequencies. Additionally, SGR J1745–2900 was observed at a different epoch at frequencies = 296–472 GHz using the APEX 12-m radio telescope, with no detections. Over the period MJD 56859.83-56862.93 the fitted spectrum yields a spectral index of 〈α〉 = –0.4 ± 0.1 for a reference flux density 〈 S 154 〉 = 1.1 ± 0.2 mJy (with S α ), a flat spectrum alike those of the other radio-loud magnetars. These results show that strongly magnetized neutron stars can be effective radio emitters at frequencies notably higher to what was previously known and that pulsar searches in the Galactic Centre are possible in the millimetre band.

Description: We compared the total mass density profiles of three different types of galaxies using weak gravitational lensing: (i) 29 galaxies that host quasars at $\bar{z}\sim 0.32$ that are in a post-starburst quasar (PSQ) phase with high star formation indicating recent merger activity, (ii) 22 large elliptical galaxies from the Sloan Lens ACS Survey (SLACS) sample that do not host a quasar at $\bar{z}\sim 0.23$ , and (iii) 17 galaxies that host moderately luminous quasars at $\bar{z}\sim 0.36$ powered by disc instabilities, but with no intense star formation. In an initial test we found no evidence for a connection between the merger state of a galaxy and the profile of the halo, with the PSQ profile comparable to that of the other two samples and consistent with the Leauthaud et al. study of moderately luminous quasars in Cosmic Evolution Survey (COSMOS). Given the compatibility of the two quasar samples, we combined these and found no evidence for any connection between black hole activity and the dark matter halo. All three mass profiles remained compatible with isothermality given the present data.

Description: The barycenter of a massive black hole binary will lie outside the event horizon of the primary black hole for modest values of mass ratio and binary separation. Analogous to radial velocity shifts in stellar emission lines caused by the tug of planets, the radial velocity of the primary black hole around the barycenter can leave a tell-tale oscillation in the broad component of FeKα emission from accreting gas. Near-future X-ray telescopes such as Astro-H and Athena will have the energy resolution ( E / E   10 –3 ) to search nearby active galactic nuclei (AGN) for the presence of binaries with mass ratios q   0.01, separated by several hundred gravitational radii. The general-relativistic and Lense–Thirring precession of the periapse of the secondary orbit imprints a detectable modulation on the oscillations. The lowest mass binaries in AGN will oscillate many times within typical X-ray exposures, leading to a broadening of the line wings and an overestimate of black hole spin in these sources. Detection of periodic oscillations in the AGN line centroid energy will reveal a massive black hole binary close to merger and will provide an early warning of gravitational radiation emission.

Description: The blazar S5 0716+714 has been monitored in its flaring state between 2015 January 19 and February 22 with the Swift X-Ray Telescope ( Swift /XRT). During this period, an exceptional flux level was observed in the X-ray range as well as at other wavelengths, e.g. optical, near-infrared and very-high-energy rays. Here, we report X-ray observations of S5 0716+714 carried out during the outburst. The observed X-ray spectra, well described by a broken power-law model, disentangle both synchrotron and inverse Compton components. The break energy shifts towards higher energies with increasing flux, revealing the dominance of synchrotron radiation in the X-ray spectrum observed. We also report spectrum softening with increasing flux. During the recent flare, significant temporal intranight variability is observed in the X-ray range.

Description: Only a handful of quasars have been identified as kinetically dominated, their long-term time-averaged jet power, $\overline{Q}$ , exceeds the bolometric thermal emission, L bol , associated with the accretion flow. This Letter presents the first extreme ultraviolet (EUV) spectrum of a kinetically dominated quasar, 3C 270.1. The EUV continuum flux density of 3C 270.1 is very steep, $F_{\nu } \sim \nu ^{-\alpha _{{\rm EUV}}}$ , α EUV  = 2.98 ± 0.15. This value is consistent with the correlation of $\overline{Q}/L_{{\rm bol}}$ and α EUV found in previous studies of the EUV continuum of quasars, the EUV deficit of radio loud quasars. Curiously, although ultraviolet broad absorption line (BAL) troughs in quasar spectra are anticorrelated with $\overline{Q}$ , 3C 270.1 has been considered a BAL quasar based on an SDSS spectrum. This claim is examined in terms of the EUV spectrum of O vi and the highest resolution C iv spectrum in the archival data and the SDSS spectrum. First, from [O iii ]4959,5007 (IR) observations and the UV spectral lines, it is concluded that the correct redshift for 3C 270.1 is 1.5266. It is then found that the standard measure of broad absorption, BALnicity = 0, for Mg ii 2800, C iv 1549 and O vi 1032 in all epochs.

Description: Observed galaxy clustering exhibits local transverse statistical isotropy around the line of sight (LOS). The variation of the LOS across a galaxy survey complicates the measurement of the observed clustering as a function of the angle to the LOS, as fast Fourier transforms (FFTs) based on Cartesian grids, cannot individually allow for this. Recent advances in methodology for calculating LOS-dependent clustering in Fourier space include the realization that power spectrum LOS-dependent moments can be constructed from sums over galaxies, based on approximating the LOS to each pair of galaxies by the LOS to one of them. We show that we can implement this method using multiple FFTs, each measuring the LOS-weighted clustering along different axes. The N log N nature of FFTs means that the computational speed-up is a factor of 〉1000 compared with summing over galaxies. This development should be beneficial for future projects such as DESI and Euclid which will provide an order of magnitude more galaxies than current surveys.

Description: Sco X-1 is the archetypal low-mass X-ray binary and the brightest persistent extrasolar X-ray source in the sky. It was included in the K2 Campaign 2 field and was observed continuously for 71 d with 1 min time resolution. In this Letter, we report these results and underline the potential of K2 for similar observations of other accreting compact binaries. We reconfirm that Sco X-1 shows a bimodal distribution of optical ‘high’ and ‘low’ states and rapid transitions between them on time-scales less than 3 h (or 0.15 orbits). We also find evidence that this behaviour has a typical systemic time-scale of 4.8 d, which we interpret as a possible disc precession period in the system. Finally, we confirm the complex optical versus X-ray correlation/anticorrelation behaviour for ‘high’ and ‘low’ optical states, respectively.

Description: Gamma-ray bursts (GRBs) are violent explosions, coming from cosmological distances. They are detected in gamma-rays (also X-rays, UV, optical, radio) almost every day, and have typical durations of a few seconds to a few minutes. Some GRBs have been reported with extraordinary durations of 10 4  s, the so-called ultralong GRBs. It has been debated whether these form a new distinct class of events or whether they are similar to long GRBs. According to Blandford & Znajek, the spin energy of a rotating black hole can be extracted electromagnetically, should the hole be endowed with a magnetic field supported by electric currents in a surrounding disc. We argue that this can be the case for the central engines of GRBs and we show that the duration of the burst depends on the magnetic flux accumulated on the event horizon of the black hole. We thus estimate the surface magnetic field of a possible progenitor star, and we conclude that an ultralong GRB may originate from a progenitor star with a relatively low magnetic field.

Description: Strong gravitational lensing provides some of the deepest views of the Universe, enabling studies of high-redshift galaxies only possible with next-generation facilities without the lensing phenomenon. To date, 21-cm radio emission from neutral hydrogen has only been detected directly out to z  ~ 0.2, limited by the sensitivity and instantaneous bandwidth of current radio telescopes. We discuss how current and future radio interferometers such as the Square Kilometre Array (SKA) will detect lensed H i emission in individual galaxies at high redshift. Our calculations rely on a semi-analytic galaxy simulation with realistic H i discs (by size, density profile and rotation), in a cosmological context, combined with general relativistic ray tracing. Wide-field, blind H i surveys with the SKA are predicted to be efficient at discovering lensed H i systems, increasingly so at z   2. This will be enabled by the combination of the magnification boosts, the steepness of the H i luminosity function at the high-mass end, and the fact that the H i spectral line is relatively isolated in frequency. These surveys will simultaneously provide a new technique for foreground lens selection and yield the highest redshift H i emission detections. More near term (and existing) cm-wave facilities will push the high-redshift H i envelope through targeted surveys of known lenses.

Description: I describe a method for synthesizing photometric passbands for use with current and future X-ray instruments. The method permits the standardization of X-ray passbands and thus X-ray photometry between different instruments and missions. The method is illustrated by synthesizing a passband in the XMM–Newton European Photon Imaging Camera pn which is similar to the ROSAT Position Sensitive Proportional Counter 0.5–2 keV band.

Description: The epidermal growth factor (EGF)-like repeat is a common, evolutionarily conserved motif found in secreted proteins and the extracellular domain of transmembrane proteins. EGF repeats harbor six cysteine residues which form three disulfide bonds and help generate the three-dimensional structure of the EGF repeat. A subset of EGF repeats harbor consensus sequences for the addition of one or more specific O -glycans, which are initiated by O -glucose, O -fucose or O - N -acetylglucosamine. These glycans are relatively rare compared to mucin-type O -glycans. However, genetic experiments in model organisms and cell-based assays indicate that at least some of the glycosyltransferases involved in the addition of O -glycans to EGF repeats play important roles in animal development. These studies, combined with state-of-the-art biochemical and structural biology experiments have started to provide an in-depth picture of how these glycans regulate the function of the proteins to which they are linked. In this review, we will discuss the biological roles assigned to EGF repeat O -glycans and the corresponding glycosyltransferases. Since Notch receptors are the best studied proteins with biologically-relevant O -glycans on EGF repeats, a significant part of this review is devoted to the role of these glycans in the regulation of the Notch signaling pathway. We also discuss recently identified proteins other than Notch which depend on EGF repeat glycans to function properly. Several glycosyltransferases involved in the addition or elongation of O -glycans on EGF repeats are mutated in human diseases. Therefore, mechanistic understanding of the functional roles of these carbohydrate modifications is of interest from both basic science and translational perspectives.

Description: We analyse FORS2/VLT I -band imaging data to monitor the motions of both components in the nearest known binary brown dwarf WISE J104915.57-531906.1AB (LUH 16) over one year. The astrometry is dominated by parallax and proper motion, but with a precision of ~0.2 mas per epoch we accurately measure the relative position change caused by the orbital motion of the pair. This allows us to directly measure a mass ratio of q  = 0.78 ± 0.10 for this system. We also search for the signature of a planetary-mass companion around either of the A and B component and exclude at 3 the presence of planets with masses larger than 2 M J and orbital periods of 20–300 d. We update the parallax of LUH 16 to 500.51 ± 0.11 mas, i.e. just within 2 pc. This study yields the first direct constraint on the mass ratio of LUH 16 and shows that the system does not harbour any close-in giant planets.

Description: The Kepler mission was launched in 2009 and has discovered thousands of planet candidates. In a recent paper, Esteves et al. found a periodic signal in the light curves of KOI-13 and HAT-P-7, with a frequency triple the orbital frequency of a transiting planet. We found similar harmonics in many systems with a high occurrence rate. At this time, the origins of the signal are not entirely certain. We look carefully at the possibility of errors being introduced through our data processing routines but conclude that the signal is real. The harmonics on multiples of the orbital frequency are a result of non-sinusoidal periodic signals. We speculate on their origin and generally caution that these harmonics could lead to wrong estimates of planet albedos, beaming mass estimates, and ellipsoidal variations.

Description: The sialyl Lewis a and x (sLe a/x ) antigens frequently displayed on the surface of tumor cells are involved in metastasis. Their synthesis has been attributed to altered expression of selective glycosyltransferases. Identification of these glycosyltransferases and the glycoproteins that carry these carbohydrate antigens should help advance our understanding of selectin-mediated cancer metastasis. In this study, quantitative real-time polymerase chain reaction analysis coupled with in situ proximity ligation assay and small interference RNA treatment shows involvement of β3galactosyltransferase-V in the synthesis of MUC16-associated sLe a in H292 cells. Also, α3fucosyltransferase-V, which is absent in BEAS-2B human immortalized bronchial epithelial cells and A549 lung carcinoma cells, participates in the synthesis of MUC1-associated sLe x in CFT1 human immortalized bronchial epithelial cells and H292 lung carcinoma cells. Neither selectin ligand is found on MUC1 in BEAS-2B and A549 cells. Knockdown of either enzyme suppresses migration, and selectin tethering and rolling properties of H292 cells under dynamic flow as determined by wound healing and parallel plate flow chamber assays, respectively. These results provide insights into how the synthesis of mucin-associated selectin ligands and the metastatic properties of cancer cells can be regulated by selective glycosyltransferases that work on mucins. They may help develop novel anticancer drugs.

Description: Chondroitin sulfate E (CSE) is a polysaccharide containing mainly disaccharide units of d -glucuronic acid (GlcA) and 4,6- O -disulfated N -acetyl- d -galactosamine (GalNAc) residues (E-unit) in the amount of ~60%. CSE is involved in many biological and pathological processes. In this study, we established new monoclonal antibodies, termed E-12C and E-18H, by using CSE that contained more than 70% of E-units as an immunogen. These antibodies recognized CSE but not other CSs isomers or dermatan sulfate (DS). We evaluated the reactivities of the antibodies to 6- O -sulfated CSA (6S-CSA) and DS (6S-DS) that possessed ~60% of GalNAc (4S, 6S) moieties in their structures. Neither of the antibodies reacted with 6S-DS. The antibodies strictly distinguished the structural difference of GlcA and l -iduronic acid in the polysaccharide. Binding affinities of the antibodies were determined by a surface plasmon resonance assay using CSE and 6S-CSA. The binding affinities were strongly associated with the molecular weight of CSE and the E-unit content of 6S-CSA. Moreover, we demonstrated that the antibodies are applicable to histochemical analysis. In conclusion, the new anti-CSE monoclonal antibodies specifically recognize the E-unit of CSE. The antibodies will become useful tools for the investigation of the biological and pathological significance of CSE.

Description: D-Galactose-binding lectin from the octocoral, Sinularia lochmodes (SLL-2), distributes densely on the cell surface of microalgae, Symbiodinium sp., an endosymbiotic dinoflagellate of the coral, and is also shown to be a chemical cue that transforms dinoflagellate into a non-motile (coccoid) symbiotic state. SLL-2 binds with high affinity to the Forssman antigen ( N -acetylgalactosamine(GalNAc)α1-3GalNAcβ1-3Galα1-4Galβ1-4Glc-ceramide), and the presence of Forssman antigen-like sugar on the surface of Symbiodinium CS-156 cells was previously confirmed. Here we report the crystal structures of SLL-2 and its GalNAc complex as the first crystal structures of a lectin involved in the symbiosis between coral and dinoflagellate. N -Linked sugar chains and a galactose derivative binding site common to H-type lectins were observed in each monomer of the hexameric SLL-2 crystal structure. In addition, unique sugar-binding site-like regions were identified at the top and bottom of the hexameric SLL-2 structure. These structural features suggest a possible binding mode between SLL-2 and Forssman antigen-like pentasaccharide.

Description: The Kepler space mission provided a wealth of  Sct– Dor hybrid candidates. While some may be genuine hybrids, others might be misclassified due to the presence of a binary companion or to rotational modulation caused by magnetism and related surface inhomogeneities. In particular, the Kepler  Sct– Dor hybrid candidate HD 188774 shows a few low frequencies in its light and radial velocity curves, whose origin is unclear. In this work, we check for the presence of a magnetic field in HD 188774. We obtained two spectropolarimetric measurements with an Echelle SpectroPolarimetric Device for the Observation of Stars (ESPaDOnS) at Canada–France–Hawaii Telescope. The data were analysed with the least-squares deconvolution (LSD) method. We detected a clear magnetic signature in the Stokes V LSD profiles. The origin of the low frequencies detected in HD 188774 is therefore most probably the rotational modulation of surface spots possibly related to the presence of a magnetic field. Consequently, HD 188774 is not a genuine hybrid  Sct– Dor star, but the first known magnetic main-sequence  Sct star. This makes it a prime target for future asteroseismic and spot modelling. This result casts new light on the interpretation of the Kepler results for other  Sct– Dor hybrid candidates.

Description: Both gamma-ray bursts (GRBs) and blazars have relativistic jets pointing at a small angle from our line of sight. Several recent studies suggested that these two kinds of sources may share similar jet physics. In this work, we explore the variability properties for GRBs and blazars as a whole. We find that the correlation between minimum variability time-scale (MTS) and Lorentz factor, , as found only in GRBs by Sonbas et al. can be extended to blazars with a joint correlation of MTS –4.7±0.3 . The same applies to the $\rm MTS\propto \it L_{\gamma }^{\rm -1.0\pm 0.1}$ correlation as found in GRBs, which can be well extended into blazars as well. These results provide further evidence that the jets in these two kinds of sources are similar despite of the very different mass scale of their central engines. Further investigations of the physical origin of these correlations are needed, which can shed light on the nature of the jet physics.

Description: In order to explain rapid light-curve variability without invoking a variable source, several authors have proposed ‘minijets’ that move relativistically relative to the main flow of the jet. Here, we consider the possibility that these minijets, instead of being isotropically distributed in the comoving frame of the jet, form primarily perpendicular to the direction of the flow, as the jet dissipates its energy at a large emission radius. This yields two robust features. First, the emission is significantly delayed compared with the isotropic case. This delay allows for the peak of the afterglow emission to appear while the source is still active, in contrast to the simplest isotropic model. Secondly, the flux decline after the source turns off is steeper than the isotropic case. We find that these two features are realized in gamma-ray bursts (GRBs). (1) The peak of most GeV light curves (ascribed to the external shock) appears during the prompt emission phase. (2) Many X-ray light curves exhibit a period of steep decay, which is faster than that predicted by the standard isotropic case. The gamma-ray generation mechanism in GRBs, and possibly in other relativistic flows, may therefore be anisotropic.

Description: Walker et al.'s Magellan/Michigan/MIKE Fiber System (MMFS) survey identified 1355 red giant candidates in the dwarf spheroidal galaxy Sculptor. We find that the Gaia satellite will be able to measure the proper motions of 139 of these with a precision of between 13 and 20 km s –1 . Using a Jeans analysis and 5-parameter density model we show that this allows a determination of the mass within the deprojected half-light radius to within 16 per cent and a measurement of the dark matter density exponent to within 0.68 within that radius. If, even at first light, the Thirty Meter Telescope (TMT) observes Sculptor then the combined observations will improve the precision on these proper motions to about 5 km s –1 , about 5 years earlier than would be possible without Gaia , further improving the precision of to 0.27. Using a bimodal stellar population model for Sculptor the precision of improves by about 30 per cent. This suggests that Gaia (with TMT) is capable of excluding a cusped profile of the kind predicted by CDM simulations with 2 (4) of confidence.

Description: T Chamaeleontis is a young star surrounded by a transitional disc, and a plausible candidate for ongoing planet formation. Recently, a substellar companion candidate was reported within the disc gap of this star. However, its existence remains controversial, with the counter-hypothesis that light from a high-inclination disc may also be consistent with the observed data. The aim of this work is to investigate the origin of the observed closure phase signal to determine if it is best explained by a compact companion. We observed T Cha in the L ' and K s filters with sparse aperture masking, with seven data sets covering a period of 3 years. A consistent closure phase signal is recovered in all L ' and K s data sets. Data were fitted with a companion model and an inclined circumstellar disc model based on known disc parameters: both were shown to provide an adequate fit. However, the absence of expected relative motion for an orbiting body over the 3-year time baseline spanned by the observations rules out the companion model. Applying image reconstruction techniques to each data set reveals a stationary structure consistent with forward scattering from the near edge of an inclined disc.

Description: We report and discuss post-explosion observations of supernova iPTF13bvn. We find that the brightness of the supernova (SN) at +740 d is below the level of the pre-explosion source and thus confirm that the progenitor has exploded. We estimate that the late-time brightness is still dominated by the SN, which constrains the magnitude and thus mass of a possible companion star to below approximately 10 M . In turn, this implies that the progenitor's initial mass is constrained to a narrow range between 10 and 12 M . The progenitor of iPTF13bvn would have been a helium giant rather than a Wolf–Rayet star. In addition, we suggest that sufficiently deep observations acquired in 2016 would now stand a chance to directly observe the companion star.

Description: We report results from a series of three-dimensional (3D) rotational core-collapse simulations for 11.2 and 27 M stars employing neutrino transport scheme by the isotropic diffusion source approximation. By changing the initial strength of rotation systematically, we find a rotation-assisted explosion for the 27 M progenitor , which fails in the absence of rotation. The unique feature was not captured in previous two-dimensional (2D) self-consistent rotating models because the growing non-axisymmetric instabilities play a key role. In the rapidly rotating case, strong spiral flows generated by the so-called low T /| W | instability enhance the energy transport from the proto-neutron star (PNS) to the gain region, which makes the shock expansion more energetic. The explosion occurs more strongly in the direction perpendicular to the rotational axis, which is different from previous 2D predictions.

Description: We discuss identification of possible counterparts and persistent sources related to fast radio bursts (FRBs) in the framework of the model of supergiant pulses from young neutron stars with large spin-down luminosities. In particular, we demonstrate that at least some of the sources of FRBs can be observed as ultraluminous X-ray sources (ULXs). At the moment no ULXs are known to be coincident with localization areas of FRBs. We searched for a correlation of FRB positions with galaxies in the 2MASS Redshift survey catalogue. Our analysis produced statistically insignificant overabundance ( p -value  4 per cent) of galaxies in error boxes of FRBs. In the very near future with even modestly increased statistics of FRBs and with the help of dedicated X-ray observations and all-sky X-ray surveys it will be possible to decisively prove or falsify the supergiant pulses model.

Description: We investigate the possible implications of quark deconfinement on the phenomenology of long gamma-ray bursts focusing, in particular, on the possibility to describe multiple prompt emission phases in the context of the proto-magnetar model . Starting from numerical models of rotating Hadron Stars and Quark Stars in full general relativity we track the electromagnetic spin-down evolution in both the hadronic and quark phase, linking the two families through conservation of baryon number and angular momentum. We give estimates of the time-scales and the energetics involved in the spin-down process deriving, in the relevant spin range, the relation between the initial and the final masses and rotational energies, whenever hadron-quark conversion is possible. We show how the results can be used in relevant astrophysical cases such as the double burst GRB 110709B.

Description: We propose that -rays in blazars can be produced during encounters of relativistic blobs of plasma with radiation field produced by luminous stars within (or close to) the jet. The blob is expected to contain relativistic electrons which Comptonize stellar radiation to the GeV–TeV energies. Produced -rays can initiate the inverse Compton e ± pair cascade in the stellar radiation. We propose that such a scenario can be responsible for the appearance of the so-called orphan -ray flares. We show that the relativistic blob/luminous star collision model can explain the appearance of the extreme orphan -ray flare observed in the GeV and sub-TeV energy range from the flat-spectrum radio quasar PKS 1222+21.

Description: In massive numerical experiments we show that a planet embedded in a planetesimal disc induces a characteristic multilane ‘planetosignature’ representing a pattern of several stellar-centric rings. If the planet's mass is large enough, the multilane signature degenerates to a three-lane one: then it consists of three rings, one bright co-orbital with the planet, and two dark gaps in the radial distribution of the particles. The gaps correspond to orbital resonances 2:1 and 1:2 with the planet. This theoretical prediction may explain recent ALMA observations of the disc of HL Tau.

Description: As a result of their internal dynamical coherence, thin stellar streams formed by disrupting globular clusters (GCs) can act as detectors of dark matter (DM) substructure in the Galactic halo. Perturbations induced by close flybys amplify into detectable density gaps, providing a probe both of the abundance and of the masses of DM subhaloes. Here, we use N -body simulations to show that the Galactic population of giant molecular clouds (GMCs) can also produce gaps (and clumps) in GC streams, and so may confuse the detection of DM subhaloes. We explore the cases of streams analogous to the observed Palomar 5 and GD1 systems, quantifying the expected incidence of structure caused by GMC perturbations. Deep observations should detect such disturbances regardless of the substructure content of the Milky Way's halo. Detailed modelling will be needed to demonstrate that any detected gaps or clumps were produced by DM subhaloes rather than by molecular clouds.

Description: The recent LIGO detection of gravitational waves (GW150914), likely originating from the merger of two ~ 30M black holes suggests progenitor stars of low metallicity ([ Z /Z ] 0.3), constraining when and where the progenitor of GW150914 may have formed. We combine estimates of galaxy properties (star-forming gas metallicity, star formation rate and merger rate) across cosmic time to predict the low redshift black hole – black hole merger rate as a function of present day host galaxy mass, M gal , the formation redshift of the progenitor system z f and different progenitor metallicities Z p . For $Z_\mathrm{p}\geqslant 0.1 \rm Z_{{\odot }}$ , the signal is dominated by binaries in massive galaxies with z f ~= 2 while below $Z_\mathrm{p}\leqslant 0.1\rm Z_{{\odot }}$ most mergers come from binaries formed around z f ~= 0.5 in dwarf galaxies. Additional gravitational wave detections from merging massive black holes will provide constraints on the mass–metallicity relation and massive star formation at high redshifts.

Description: S0 galaxies are known to host classical bulges with a broad range of size and mass, while some such S0s are barred and some not. The origin of the bars has remained a long-standing problem – what made bar formation possible in certain S0s? By analysing a large sample of S0s with classical bulges observed by the Spitzer Space Telescope , we find that most of our barred S0s host comparatively low-mass classical bulges, typically with bulge-to-total ratio less than 0.5, whereas S0s with more massive classical bulges than these do not host any bar. Furthermore, we find that amongst the barred S0s, there is a trend for the longer and massive bars to be associated with comparatively bigger and massive classical bulges – possibly suggesting bar growth being facilitated by these classical bulges. In addition, we find that the bulge effective radius is always less than the bar effective radius – indicating an interesting synergy between the host classical bulge and bars being maintained while bar growth occurred in these S0s.

Description: We make three assumptions: fast radio bursts (FRBs) are produced by neutron stars at cosmological distances; FRB rate tracks the core-collapse supernova rate; and all FRBs repeat with a universal energy distribution function (EDF) $\mathrm{d}\dot{N}/\mathrm{d}E \propto E^{-\beta }$ with a cutoff at burst energy E max . We then find that observations so far are consistent with a universal EDF with 1.5 β 2.2, high-end cutoff E max / E 0 30 and normalization $\dot{N}_0 \lesssim 2\rm \ d^{-1}$ ; where $\dot{N}_0$ is the integrated rate above the reference energy $E_0 \simeq 1.2\times 10^{39} f_{\rm r}^{-1} \rm \ erg$ ( f r is the radio emission efficiency). Implications of such an EDF are discussed.

Description: We have identified a population of passive spiral galaxies from photometry and integral field spectroscopy. We selected z  〈 0.035 spiral galaxies that have WISE colours consistent with little mid-infrared emission from warm dust. Matched aperture photometry of 51 spiral galaxies in ultraviolet, optical and mid-infrared show these galaxies have colours consistent with passive galaxies. Six galaxies form a spectroscopic pilot study and were observed using the Wide-Field Spectrograph to check for signs of nebular emission from star formation. We see no evidence of substantial nebular emission found in previous red spiral samples. These six galaxies possess absorption-line spectra with 4000 Å breaks consistent with an average luminosity-weighted age of 2.3 Gyr. Our photometric and integral field spectroscopic observations confirm the existence of a population of local passive spiral galaxies, implying that transformation into early-type morphologies is not required for the quenching of star formation.

Description: The far-infrared fine-structure line [C ii ] at 1900.5 GHz is known to be one of the brightest cooling lines in local galaxies, and therefore it has been suggested to be an efficient tracer for star formation in very high redshift galaxies. However, recent results for galaxies at z  〉 6 have yielded numerous non-detections in star-forming galaxies, except for quasars and submillimetre galaxies. We report the results of ALMA observations of two lensed, star-forming galaxies at z  = 6.029 and z  = 6.703. The galaxy A383-5.1 (star formation rate [SFR] of 3.2 M  yr –1 and magnification of μ = 11.4 ± 1.9) shows a line detection with $L_{\rm [C\,\small {II}]} = 8.9\times 10^{6}$  L , making it the lowest $L_{\rm [C\,\small {II}]}$ detection at z  〉 6. For MS0451-H (SFR = 0.4 M  yr –1 and μ = 100 ± 20) we provide an upper limit of $L_{\rm [C\,\small {II}]} 〈 3\times 10^{5}$  L , which is 1 dex below the local SFR– $L_{\rm [C\,\small {II}]}$ relations. The results are consistent with predictions for low-metallicity galaxies at z  〉 6; however, other effects could also play a role in terms of decreasing L [CII] . The detection of A383-5.1 is encouraging and suggests that detections are possible, but much fainter than initially predicted.

Description: The timing of radio pulsars in binary systems provides a superb testing ground of general relativity. Here we propose a Bayesian approach to carry out these tests, and a relevant efficient numerical implementation, that has several conceptual and practical advantages with respect to traditional methods based on least-squares fit that have been used so far: (i) it accounts for the actual structure of the likelihood function – and it is not predicated on the Laplace approximation which is implicitly built in least-squares fit that can potentially bias the inference – (ii) it provides the ratio of the evidences of any two models under consideration as the statistical quantity to compare different theories, and (iii) it allows us to put joint constraints from the monitoring of multiple systems, that can be expressed in terms of ratio of evidences or probability intervals of global (thus not system-dependent) parameters of the theory, if any exists. Our proposed approach optimally exploits the progress in timing of radio pulsars and the increase in the number of observed systems. We demonstrate the power of this framework using simulated data sets that are representative of current observations.

Description: Protein glycosylation is one of the most significant post-translation modifications and plays a critical role in various biological functions. Haptoglobin (Hp) is one of the acute-phase response proteins secreted by liver. Its glycosylation could be analyzed by many analytical techniques qualitatively and quantitatively. The glycosylation alterations of Hp are reported to be associated with different kinds of diseases. The main glycosylation alterations of Hp in cancer appear to be the presence of aberrantly fucosylated and sialylated structures as well as increased branching. In this mini review, we provided a brief overview of Hp structure and biological function, discussed its glycosylation alterations in different cancers, and described the existing technologies for analyzing glycosylation site and glycan of Hp. Given the importance of Hp glycosylation, its unknown and unclear biological complexity and significances, Hp glycosylation has become a major target in cancer research. Development of sensitive and specific detection of Hp glycosylation including large-scale validation may be significant steps forward to its clinical application.

Description: Keratan sulfate (KS) was isolated from chicken egg white in amounts corresponding to ~0.06 wt% (dry weight). This KS had a weight-average molecular weight of ~36–41 kDa with a polydispersity of ~1.3. The primary repeating unit present in chicken egg white KS was -〉4) β- N -acetyl-6- O -sulfo- d -glucosamine (1 -〉 3) β- d -galactose (1-〉 with some 6- O -sulfo galactose residues present. This KS was somewhat resistant to depolymerization using keratanase 1 but could be depolymerized efficiently through the use of reactive oxygen species generated using copper (II) and hydrogen peroxide. Of particular interest was the presence of substantial amounts of 2,8- and 2,9-linked N -acetylneuraminic acid residues in the form of oligosialic acid terminating the non-reducing ends of the KS chains. Most of the KS appears to be N -linked to a protein core as evidenced by its sensitivity to PNGase F.

Description: UDP- N -acetylglucosamine (UDP-GlcNAc) is a glucose metabolite with pivotal functions as a key substrate for the synthesis of glycoconjugates like hyaluronan, and as a metabolic sensor that controls cell functions through O-GlcNAc modification of intracellular proteins. However, little is known about the regulation of hexosamine biosynthesis that controls UDP-GlcNAc content. Four enzymes can catalyze the crucial starting point of the pathway, conversion of fructose-6-phosphate (Fru6P) to glucosamine-6-phosphate (GlcN6P): glutamine-fructose-6-phosphate aminotransferases (GFAT1 and 2) and glucosamine-6-phosphate deaminases (GNPDA1 and 2). Using siRNA silencing, we studied the contributions of these enzymes to UDP-GlcNAc content and hyaluronan synthesis in human keratinocytes. Depletion of GFAT1 reduced the cellular pool of UDP-GlcNAc and hyaluronan synthesis, while simultaneous blocking of both GNPDA1 and GDPDA2 exerted opposite effects, indicating that in standard culture conditions keratinocyte GNPDAs mainly catalyzed the reaction from GlcN6P back to Fru6P. However, when hexosamine biosynthesis was blocked by GFAT1 siRNA, the effect by GNPDAs was reversed, now catalyzing Fru6P towards GlcN6P, likely in an attempt to maintain UDP-GlcNAc content. Silencing of these enzymes also changed the gene expression of related enzymes: GNPDA1 siRNA induced GFAT2 which was hardly measurable in these cells under standard culture conditions, GNPDA2 siRNA increased GFAT1, and GFAT1 siRNA increased the expression of hyaluronan synthase 2 (HAS2). Silencing of GFAT1 stimulated GNPDA1 and GDPDA2, and inhibited cell migration. The multiple delicate adjustments of these reactions demonstrate the importance of hexosamine biosynthesis in cellular homeostasis, known to be deranged in diseases like diabetes and cancer.

Description: The balance between neutrophil serine proteases (NSPs) and protease inhibitors (PIs) in the lung is a critical determinant for a number of chronic inflammatory lung diseases such as chronic obstructive pulmonary disease, cystic fibrosis and acute lung injury. During activation at inflammatory sites, excessive release of NSPs such as human neutrophil elastase (HNE), proteinase 3 (Pr3) and cathepsin G (CatG), leads to destruction of the lung matrix and continued propagation of acute inflammation. Under normal conditions, PIs counteract these effects by inactivating NSPs; however, in chronic inflammatory lung diseases, there are insufficient amounts of PIs to mitigate damage. Therapeutic strategies are needed to modulate excessive NSP activity for the clinical management of chronic inflammatory lung diseases. In the study reported here, a panel of N- arylacyl O - sulfonated aminoglycosides was screened to identify inhibitors of the NSPs. Dose-dependent inhibitors for each individual serine protease were identified. Select compounds were found to inhibit multiple NSPs, including one lead structure that is shown to inhibit all three NSPs. Two lead compounds identified during the screen for each individual NSP were further characterized as partial mixed inhibitors of CatG. Concentration-dependent inhibition of protease-mediated detachment of lung epithelial cells is demonstrated.

Description: Galectin-12 is a member of an animal lectin family with affinity for β-galactosides and containing consensus amino acid sequences. Here, we found that galectin-12 was expressed in macrophages and thus aimed to determine how galectin-12 affects inflammation and macrophage polarization and activation. The ablation of galectin-12 did not affect bone marrow cells to differentiate into macrophages, but reduced phagocytic activity against Escherichia coli and lowered the secretion of nitric oxide. The ablation of galectin-12 also resulted in the polarization of macrophages into the M2 direction, as indicated by increases in the levels of M2 markers, namely, resistin-like β (FIZZ1) and chitinase 3-like 3 (Ym1), as well as a reduction in the expression levels of a number of M1 pro-inflammatory cytokines. We found that the diminished expression of pro-inflammatory cytokines in macrophages resulting from galectin-12 deletion was due to reduced activation of IKKα/β, Akt and ERK, which in turn caused decreased activation of NF-B and activator protein 1. The activation of STAT3 was much higher in Gal12 –/– macrophages activated by lipopolysaccharide, which was correlated with higher levels of IL-10. Adipocytes showed higher insulin sensitivity when treated with Gal12 –/– macrophage-conditioned media than those treated with Gal12 +/+ macrophages. We conclude galectin-12 negatively regulates macrophage polarization into the M2 population, resulting in enhanced inflammatory responses and also in turn causing decreased insulin sensitivity in adipocytes. This has implications in the treatment of a wide spectrum of metabolic disorders.

Description: The enzyme UDP- N -acetylglucosamine: α- d -mannoside β-1-6 N -acetylglucosaminyltransferase V (GnT-V) catalyzes the transfer of GlcNAc from the UDP-GlcNAc donor to the α-1-6-linked mannose of the trimannosyl core structure of glycoproteins to produce the β-1-6-linked branching of N-linked oligosaccharides. β-1-6-GlcNAc-branched N -glycans are associated with cancer growth and metastasis. Therefore, the inhibition of GnT-V represents a key target for anti-cancer drug development. However, the development of potent and specific inhibitors of GnT-V is hampered by the lack of information on the three-dimensional structure of the enzyme and on the binding characteristics of its substrates. Here we present the first 3D structure of GnT-V as a result of homology modeling. Various alignment methods, docking the donor and acceptor substrates, and molecular dynamics simulation were used to construct seven homology models of GnT-V and characterize the binding of its substrates. The best homology model is consistent with available experimental data. The three-dimensional model, the structure of the enzyme catalytic site and binding information obtained for the donor and acceptor can be useful in studies of the catalytic mechanism and design of inhibitors of GnT-V.

Description: Bacterial polysialyltransferases (PSTs) are processive enzymes involved in the synthesis of polysialic capsular polysaccharides. They can also synthesize polysialic acid in vitro from disialylated and trisialylated lactoside acceptors, which are the carbohydrate moieties of GD3 and GT3 gangliosides, respectively. Here, we engineered a non-pathogenic Escherichia coli strain that overexpresses recombinant sialyltransferases and sialic acid synthesis genes and can convert an exogenous lactoside into polysialyl lactosides. Several PSTs were assayed for their ability to synthesize polysialyl lactosides in the recombinant strains. Fed-batch cultures produced α-2,8 polysialic acid or alternate α-2,8–2,9 polysialic acid in quantities reaching several grams per liter. Bacterial culture in the presence of propargyl-β-lactoside as the exogenous acceptor led to the production of conjugatable polysaccharides by means of copper-assisted click chemistry.

Description: N-Glycosylation is a post-translational modification performed in all three domains of life. In the halophilic archaea Haloferax volcanii , glycoproteins such as the S-layer glycoprotein are modified by an N-linked pentasaccharide assembled by a series of Agl (archaeal glycosylation) proteins. In the present study, mass spectrometry (MS) and nuclear magnetic resonance spectroscopy were used to define the structure of this glycan attached to at least four of the seven putative S-layer glycoprotein N-glycosylation sites, namely Asn-13, Asn-83, Asn-274 and Asn-279. Such approaches detected a trisaccharide corresponding to glucuronic acid (GlcA)-β1,4-GlcA-β1,4-glucose-β1-Asn, a tetrasaccharide corresponding to methyl- O -4-GlcA-β-1,4-galacturonic acid-α1,4-GlcA-β1,4-glucose-β1-Asn, and a pentasaccharide corresponding to hexose-1,2-[methyl- O -4-]GlcA-β-1,4-galacturonic acid-α1,4-GlcA-β1,4-glucose-β1-Asn, with previous MS and radiolabeling experiments showing the hexose at the non-reducing end of the pentasaccharide to be mannose. The present analysis thus corrects the earlier assignment of the penultimate sugar as a methyl ester of a hexuronic acid, instead revealing this sugar to be a methylated GlcA. The assignments made here are in good agreement with what was already known of the Hfx. volcanii N-glycosylation pathway from previous genetic and biochemical efforts while providing new insight into the process.

Description: Defining how a glycan-binding protein (GBP) specifically selects its cognate glycan from among the ensemble of glycans within the cellular glycome is an area of intense study. Powerful insight into recognition mechanisms can be gained from 3D structures of GBPs complexed to glycans; however, such structures remain difficult to obtain experimentally. Here an automated 3D structure generation technique, called computational carbohydrate grafting, is combined with the wealth of specificity information available from glycan array screening. Integration of the array data with modeling and crystallography allows generation of putative co-complex structures that can be objectively assessed and iteratively altered until a high level of agreement with experiment is achieved. Given an accurate model of the co-complexes, grafting is also able to discern which binding determinants are active when multiple potential determinants are present within a glycan. In some cases, induced fit in the protein or glycan was necessary to explain the observed specificity, while in other examples a revised definition of the minimal binding determinants was required. When applied to a collection of 10 GBP–glycan complexes, for which crystallographic and array data have been reported, grafting provided a structural rationalization for the binding specificity of 〉90% of 1223 arrayed glycans. A webtool that enables researchers to perform computational carbohydrate grafting is available at www.glycam.org/gr (accessed 03 March 2016).

Description: We report on the discovery of a hydrogen-deficient compact binary (CXOGBS J175107.6-294037) belonging to the AM CVn class in the Galactic Bulge Survey. Deep archival X-ray observations constrain the X-ray positional uncertainty of the source to 0.57 arcsec, and allow us to uniquely identify the optical and UV counterpart. Optical spectroscopic observations reveal the presence of broad, shallow He i absorption lines while no sign of hydrogen is present, consistent with a high state system. We present the optical light curve from Optical Gravitational Lensing Experiment monitoring, spanning 15 yr. It shows no evidence for outbursts; variability is present at the 0.2 mag level on time-scales ranging from hours to weeks. A modulation on a time-scale of years is also observed. A Lomb–Scargle analysis of the optical light curves shows two significant periodicities at 22.90 and 23.22 min. Although the physical interpretation is uncertain, such time-scales are in line with expectations for the orbital and superhump periods. We estimate the distance to the source to be between 0.5 and 1.1 kpc. Spectroscopic follow-up observations are required to establish the orbital period, and to determine whether this source can serve as a verification binary for the eLISA gravitational wave mission.

Description: We report on Fermi /Large Area Telescope observations of the accreting black hole low-mass X-ray binary V404 Cygni during its outburst in 2015 June–July. Detailed analyses reveal a possible excess of -ray emission on 2015 26 June, with a very soft spectrum above 100 MeV, at a position consistent with the direction of V404 Cyg (within the 95 per cent confidence region and a chance probability of 4 x 10 –4 ). This emission cannot be associated with any previously known Fermi source. Its temporal coincidence with the brightest radio and hard X-ray flare in the light curve of V404 Cyg, at the end of the main active phase of its outburst, strengthens the association with V404 Cyg. If the -ray emission is associated with V404 Cyg, the simultaneous detection of 511 keV annihilation emission by INTEGRAL reqires that the high-energy -rays originate away from the corona, possibly in a Blandford–Znajek jet. The data give support to models involving a magnetically arrested disc where a bright -ray jet can re-form after the occurrence of a major transient ejection seen in the radio.

Description: The gap between two component debris discs is often taken to be carved by intervening planets scattering away the remnant planetesimals. We employ N -body simulations to determine how the time needed to clear the gap depends on the location of the gap and the mass of the planets. We invert this relation, and provide an equation for the minimum planet mass, and another for the expected number of such planets, that must be present to produce an observed gap for a star of a given age. We show how this can be combined with upper limits on the planetary system from direct imaging non-detections (such as with GPI or SPHERE) to produce approximate knowledge of the planetary system.

Description: Here we present a simple, parameter-free, non-perturbative algorithm that gives low-redshift cosmological particle realizations accurate to few-Megaparsec scales, called muscle (MUltiscale Spherical-ColLapse Evolution). It has virtually the same cost as producing N -body-simulation initial conditions, since it works with the ‘stretch’ parameter , the Lagrangian divergence of the displacement field. It promises to be useful in quickly producing mock catalogues, and to simplify computationally intensive reconstructions of galaxy surveys. muscle applies a spherical-collapse prescription on multiple Gaussian-smoothed scales. It achieves higher accuracy than perturbative schemes (Zel'dovich and second-order Lagrangian perturbation theory – 2LPT), and, by including the void-in-cloud process (voids in large-scale collapsing regions), solves problems with a single-scale spherical-collapse scheme. Slight further improvement is possible by mixing in the 2LPT estimate on large scales. Additionally, we show the behaviour of for different morphologies (voids, walls, filaments, and haloes). A python code to produce these realizations is available at http://skysrv.pha.jhu.edu/~neyrinck/muscle.html .

Description: The cold disc/torus gas surrounding active galactic nuclei (AGN) emits fluorescent lines when irradiated by hard X-ray photons. The fluorescent lines of elements other than Fe and Ni are rarely detected due to their relative faintness. We report the detection of Kα lines of neutral Si, S, Ar, Ca, Cr, and Mn, along with the prominent Fe Kα, Fe Kβ, and Ni Kα lines, from the deep Chandra observation of the low-luminosity Compton-thick AGN in M51. The Si Kα line at 1.74 keV is detected at ~3, the other fluorescent lines have a significance between 2 and 2.5 , while the Cr line has a significance of ~1.5. These faint fluorescent lines are made observable due to the heavy obscuration of the intrinsic spectrum of M51, which is revealed by NuSTAR observation above 10 keV. The hard X-ray continuum of M51 from Chandra and NuSTAR can be fitted with a power-law spectrum with an index of 1.8, reprocessed by a torus with an equatorial column density of N H  ~ 7  x  10 24  cm –2 and an inclination angle of 74°. This confirms the Compton-thick nature of the nucleus of M51. The relative element abundances inferred from the fluxes of the fluorescent lines are similar to their solar values, except for Mn, which is about 10 times overabundant. It indicates that Mn is likely enhanced by the nuclear spallation of Fe.

Description: High-precision time series photometry with the Kepler satellite has been crucial to our understanding both of exoplanets, and via asteroseismology, of stellar physics. After the failure of two reaction wheels, the Kepler satellite has been repurposed as Kepler -2 (K2), observing fields close to the ecliptic plane. As these fields contain many more bright stars than the original Kepler field, K2 provides an unprecedented opportunity to study nearby objects amenable to detailed follow-up with ground-based instruments. Due to bandwidth constraints, only a small fraction of pixels can be downloaded, with the result that most bright stars which saturate the detector are not observed. We show that engineering data acquired for photometric calibration, consisting of collateral ‘smear’ measurements, can be used to reconstruct light curves for bright targets not otherwise observable with Kepler /K2. Here we present some examples from Kepler Quarter 6 and K2 Campaign 3, including the Scuti variables HD 178875 and 70 Aqr, and the red giant HR 8500 displaying solar-like oscillations. We compare aperture and smear photometry where possible, and also study targets not previously observed. These encouraging results suggest this new method can be applied to most Kepler and K2 fields.

Description: Though Fourier transforms (FTs) are a common technique for finding correlation functions, they are not typically used in computations of the anisotropy of the two-point correlation function (2PCF) about the line of sight in wide-angle surveys because the line-of-sight direction is not constant on the Cartesian grid. Here we show how FTs can be used to compute the multipole moments of the anisotropic 2PCF. We also show how FTs can be used to accelerate the 3PCF algorithm of Slepian & Eisenstein. In both cases, these FT methods allow one to avoid the computational cost of pair counting, which scales as the square of the number density of objects in the survey. With the upcoming large data sets of Dark Energy Spectroscopic Instrument, Euclid , and Large Synoptic Survey Telescope, FT techniques will therefore offer an important complement to simple pair or triplet counts.

Description: Stars orbiting within 1 arcsec of the supermassive black hole in the Galactic Centre, Sgr A*, are notoriously difficult to detect due to obscuration by gas and dust. We show that some stars orbiting this region may be detectable via synchrotron emission. In such instances, a bow shock forms around the star and accelerates the electrons. We calculate that around the 10 GHz band (radio) and at 10 14  Hz (infrared) the luminosity of a star orbiting the black hole is comparable to the luminosity of Sgr A*. The strength of the synchrotron emission depends on a number of factors including the star's orbital velocity. Thus, the ideal time to observe the synchrotron flux is when the star is at pericentre. The star S2 will be ~0.015 arcsec from Sgr A* in 2018, and is an excellent target to test our predictions.

Description: The average white dwarf (WD) masses in cataclysmic variables (CVs) have been measured to significantly exceed those of single WDs, which is the opposite of what is theoretically expected. We present the results of binary population synthesis models taking into account consequential angular momentum loss (CAML) that is assumed to increase with decreasing WD mass. This approach cannot only solve the WD mass problem but also brings in agreement theoretical predictions and observations of the orbital period distribution and the space density of CVs. We speculate that frictional angular momentum loss following nova eruptions might cause such CAML and could be the missing ingredient of CV evolution.

Description: We have measured the linear polarization of hard X-ray emission from the Crab in a previously unexplored energy interval, 20–120 keV. The introduction of two new observational parameters, the polarization fraction and angle stands to disentangle geometrical and physical effects, thereby providing information on the pulsar wind geometry and magnetic field environment. Measurements are conducted using the PoGOLite Pathfinder – a balloon-borne polarimeter. Polarization is determined by measuring the azimuthal Compton scattering angle of incident X-rays in an array of plastic scintillators housed in an anticoincidence well. The polarimetric response has been characterized prior to flight using both polarized and unpolarized calibration sources. We address possible systematic effects through observations of a background field. The measured polarization fraction for the integrated Crab light curve is $18.4^{+9.8}_{-10.6}$  per cent, corresponding to an upper limit (99 per cent credibility) of 42.4 per cent, for a polarization angle of (149.2 ± 16.0)°.

Description: Here we introduce moments of visibility function and discuss how those can be used to estimate the power spectrum of the turbulent velocity of external spiral galaxies. We perform numerical simulation to confirm the credibility of this method and found that for galaxies with lower inclination angles it works fine. The estimator outlined here is unbiased and has the potential to recover the turbulent velocity spectrum completely from radio interferometric observations.

Description: Using deep Hubble and Spitzer observations Oesch et al. have identified a bright ( M UV –22) star-forming galaxy candidate at z 11. The presence of GN- z 11 implies a number density ~10 –6 Mpc –3 , roughly an order of magnitude higher than the expected value based on extrapolations from lower redshift. Using the unprecedented volume and high resolution of the B lue T ides cosmological hydrodynamical simulation, we study the population of luminous rare objects at z 〉 10. The luminosity function in B lue T ides implies an enhanced number of massive galaxies, consistent with the observation of GN- z 11. We find about 30 galaxies at M UV –22 at z = 11 in the B lue T ides volume, including a few objects about 1.5 mag brighter. The probability of observing GN- z 11 in the volume probed by Oesch et al. is ~13 per cent. The predicted properties of the rare bright galaxies at z = 11 in B lue T ides closely match those inferred from the observations of GN- z 11. B lue T ides predicts a negligible contribution from faint AGN in the observed SED. The enormous increase in volume surveyed by WFIRST will provide observations of ~1000 galaxies with M UV 〈 –22 beyond z = 11 out to z = 13.5.

Description: We report the discovery of an optical Einstein ring in the Sculptor constellation, IAC J010127-334319, in the vicinity of the Sculptor dwarf spheroidal galaxy. It is an almost complete ring (~300°) with a diameter of ~4.5 arcsec. The discovery was made serendipitously from inspecting Dark Energy Camera (DECam) archive imaging data. Confirmation of the object nature has been obtained by deriving spectroscopic redshifts for both components, lens and source, from observations at the 10.4 m Gran Telescopio CANARIAS (GTC) with the spectrograph OSIRIS. The lens, a massive early-type galaxy, has a redshift of z  = 0.581, while the source is a starburst galaxy with redshift of z  = 1.165. The total enclosed mass that produces the lensing effect has been estimated to be M tot  = (1.86 ± 0.23) x 10 12 M .

Description: Energy deposition by active galactic nuclei jets into the ambient medium can affect galaxy formation and evolution, the cooling of gas flows at the centres of galaxy clusters, and the growth of the supermassive black holes. However, the processes that couple jet power to the ambient medium and determine jet morphology are poorly understood. For instance, there is no agreement on the cause of the well-known Fanaroff–Riley (FR) morphological dichotomy of jets, with FRI jets being shorter and less stable than FRII jets. We carry out global 3D magnetohydrodynamic simulations of relativistic jets propagating through the ambient medium. We show that the flat density profiles of galactic cores slow down and collimate the jets, making them susceptible to the 3D magnetic kink instability. We obtain a critical power, which depends on the galaxy core mass and radius, below which jets become kink-unstable within the core, stall, and inflate cavities filled with relativistically hot plasma. Jets above the critical power stably escape the core and form powerful backflows. Thus, the kink instability controls the jet morphology and can lead to the FR dichotomy. The model-predicted dependence of the critical power on the galaxy optical luminosity agrees well with observations.

Description: Pulsar glitches, sudden jumps in frequency observed in many radio pulsars, may be the macroscopic manifestation of superfluid vortex avalanches on the microscopic scale. Small-scale quantum mechanical simulations of vortex motion in a decelerating container have shown that such events are possible and predict power-law distributions for the size of the events, and exponential distributions for the waiting time. Despite a paucity of data, this prediction is consistent with the size and waiting time distributions of most glitching pulsars. Nevertheless, a few object appear to glitch quasi-periodically, and exhibit many large glitches, while a recent study of the Crab pulsar has suggested deviations from a power-law distribution for smaller glitches. In this Letter, we incorporate the results of quantum mechanical simulations in a macroscopic superfluid hydrodynamics simulation. We show that the effect of vortex coupling to the neutron and proton fluids in the star naturally leads to deviations from power-law distributions for sizes, and from exponential distributions for waiting times, and we predict a cutoff in the size distribution for small glitches.

Description: We investigate the presence and importance of dark matter discs in a sample of 24 simulated Milky Way galaxies in the apostle project, part of the eagle programme of hydrodynamic simulations in CDM cosmology. It has been suggested that a dark disc in the Milky Way may boost the dark matter density and modify the velocity modulus relative to a smooth halo at the position of the Sun, with ramifications for direct detection experiments. From a kinematic decomposition of the dark matter and a real space analysis of all 24 haloes, we find that only one of the simulated Milky Way analogues has a detectable dark disc component. This unique event was caused by a merger at late time with an LMC-mass satellite at very low grazing angle. Considering that even this rare scenario only enhances the dark matter density at the solar radius by 35 per cent and affects the high-energy tail of the dark matter velocity distribution by less than 1 per cent, we conclude that the presence of a dark disc in the Milky Way is unlikely, and is very unlikely to have a significant effect on direct detection experiments.

Description: We carry out controlled N -body simulations that follow the dynamical evolution of binary stars in the dark matter (DM) haloes of ultrafaint dwarf spheroidals (dSphs). We find that wide binaries with semimajor axes a a t tend to be quickly disrupted by the tidal field of the halo. In smooth potentials the truncation scale, a t , is mainly governed by (i) the mass enclosed within the dwarf half-light radius ( R h ) and (ii) the slope of the DM halo profile at R R h , and is largely independent of the initial eccentricity distribution of the binary systems and the anisotropy of the stellar orbits about the galactic potential. For the reported velocity dispersion and half-light radius of Segue I, the closest ultrafaint, our models predict a t values that are a factor of 2–3 smaller in cuspy haloes than in any of the cored models considered here. Using mock observations of Segue I we show that measuring the projected two-point correlation function of stellar pairs with sub-arcsecond resolution may provide a useful tool to constrain the amount and distribution of DM in the smallest and most DM-dominated galaxies.

Description: We present the study of the colour–magnitude diagram of the cluster Abell 2151 (A 2151), with a particular focus on the low-mass end. The deep spectroscopy with AF2/WYFFOS@WHT and the caustic method enable us to obtain 360 members within 1.3 R 200 and absolute magnitude $M_r \lesssim M_r^{\ast }+6$ . This nearby cluster shows a well defined red sequence up to M r  ~ –18.5; at fainter magnitudes only 36 per cent of the galaxies lie on the extrapolation of the red sequence. We compare the red sequences of A 2151 and Abell 85, which is another nearby cluster with similar spectroscopic data, but with different mass and dynamical state. Both clusters show similar red sequences at the bright end ( M r ≤ –19.5), whereas large differences appear at the faint end. This result suggests that the reddening of bright galaxies is independent of environment, unlike the dwarf population ( M r ≥ –18.0).

Description: Symbiotic star surveys have traditionally relied almost exclusively on low resolution optical spectroscopy. However, we can obtain a more reliable estimate of their total Galactic population by using all available signatures of the symbiotic phenomenon. Here we report the discovery of a hard X-ray source, 4PBC J0642.9+5528, in the Swift hard X-ray all-sky survey, and identify it with a poorly studied red giant, SU Lyn, using pointed Swift observations and ground-based optical spectroscopy. The X-ray spectrum, the optical to UV spectrum, and the rapid UV variability of SU Lyn are all consistent with our interpretation that it is a symbiotic star containing an accreting white dwarf. The symbiotic nature of SU Lyn went unnoticed until now, because it does not exhibit emission lines strong enough to be obvious in low resolution spectra. We argue that symbiotic stars without shell-burning have weak emission lines, and that the current lists of symbiotic stars are biased in favour of shell-burning systems. We conclude that the true population of symbiotic stars has been underestimated, potentially by a large factor.

Description: The Planet Nine hypothesis has now enough constraints to deserve further attention in the form of detailed numerical experiments. The results of such studies can help us improve our understanding of the dynamical effects of such a hypothetical object on the extreme trans-Neptunian objects or ETNOs and perhaps provide additional constraints on the orbit of Planet Nine itself. Here, we present the results of direct N -body calculations including the latest data available on the Planet Nine conjecture. The present-day orbits of the six ETNOs originally linked to the hypothesis are evolved backwards in time and into the future under some plausible incarnations of the hypothesis to investigate if the values of several orbital elements, including the argument of perihelion, remain confined to relatively narrow ranges. We find that a nominal Planet Nine can keep the orbits of (90377) Sedna and 2012 VP 113 relatively well confined in orbital parameter space for hundreds of Myr, but it may make the orbits of 2004 VN 112 , 2007 TG 422 and 2013 RF 98 very unstable on time-scales of dozens of Myr, turning them retrograde and eventually triggering their ejection from the Solar system. Far more stable orbital evolution is found with slightly modified orbits for Planet Nine.

Description: We use the Evolution and Assembly of GaLaxies and their Environments (EAGLE) galaxy formation simulation to study the effects of baryons on the power spectrum of the total matter and dark matter distributions and on the velocity fields of dark matter and galaxies. On scales k 4 h Mpc –1 the effect of baryons on the amplitude of the total matter power spectrum is greater than 1 per cent. The back-reaction of baryons affects the density field of the dark matter at the level of ~3 per cent on scales of 1 ≤ k /( h Mpc –1 ) ≤ 5. The dark matter velocity divergence power spectrum at k 0.5 h Mpc –1 is changed by less than 1 per cent. The 2D redshift space power spectrum is affected at the level of ~6 per cent at $|\boldsymbol {k}|\gtrsim 1\,h\,{\rm Mpc}^{-1}$ (for μ 〉 0.5), but for $|\boldsymbol {k}|\le 0.4\,h\,{\rm Mpc}^{-1}$ it differs by less than 1 per cent. We report vanishingly small baryonic velocity bias for haloes: the peculiar velocities of haloes with M 200  〉 3  x  10 11 M (hosting galaxies with M * 〉 10 9 M ) are affected at the level of at most 1 km s –1 , which is negligible for 1 per cent-precision cosmology. We caution that since EAGLE overestimates cluster gas fractions it may also underestimate the impact of baryons, particularly for the total matter power spectrum. Nevertheless, our findings suggest that for theoretical modelling of redshift space distortions and galaxy velocity-based statistics, baryons and their back-reaction can be safely ignored at the current level of observational accuracy. However, we confirm that the modelling of the total matter power spectrum in weak lensing studies needs to include realistic galaxy formation physics in order to achieve the accuracy required in the precision cosmology era.

Description: At redshift larger than 3 there is a disagreement between the number of blazars (whose jet is pointing at us) and the number of expected parents (whose jet is pointing elsewhere). Now we strengthen this claim because (i) the number of blazars identified within the Sloan Digital Sky Survey (SDSS)+Faint Images of the Radio Sky at Twenty-cm (FIRST) survey footprint increased, demanding a more numerous parent population, and (ii) the detected blazars have a radio flux large enough to be above the FIRST flux limit even if the jet is slightly misaligned. The foreseen number of these slightly misaligned jets, in principle detectable, is much larger than the radio-detected sources in the FIRST+SDSS survey (at redshift larger than 4). This argument is independent of the presence of an isotropic radio component, such as the hotspot or the radio lobe, and does not depend on the bulk Lorentz factor . We propose a scenario that ascribes the lack of slightly misaligned sources to an overobscuration of the nucleus by a ‘bubble’ of dust, possibly typical of the first high-redshift quasars.

Description: Image cubes of differential column density as a function of dust temperature are constructed for Galactic Centre molecular cloud G0.253+0.016 (‘The Brick’) using the recently described PPMAP procedure. The input data consist of continuum images from the Herschel Space Telescope in the wavelength range 70–500 μm, supplemented by previously published interferometric data at 1.3 mm wavelength. While the bulk of the dust in the molecular cloud is consistent with being heated externally by the local interstellar radiation field, our image cube shows the presence, near one edge of the cloud, of a filamentary structure whose temperature profile suggests internal heating. The structure appears as a cool (~14 K) tadpole-like feature, ~6 pc in length, in which is embedded a thin spine of much hotter (~40–50 K) material. We interpret these findings in terms of a cool filament whose hot central region is undergoing gravitational collapse and fragmentation to form a line of protostars. If confirmed, this would represent the first evidence of widespread star formation having started within this cloud.

Description: Observations reveal that quasar host haloes at z ~ 2 have large covering fractions of cool dense gas (60 per cent for Lyman limit systems within a projected virial radius). Most simulations have so far failed to explain these large observed covering fractions. We analyse a new set of 15 simulated massive haloes with explicit stellar feedback from the FIRE project, covering the halo mass range M h 2 x 10 12 – 10 13 M at z = 2. This extends our previous analysis of the circum-galactic medium of high-redshift galaxies to more massive haloes. Active galactic nuclei (AGN) feedback is not included in these simulations. We find Lyman limit system covering fractions consistent with those observed around quasars. The large H  i covering fractions arise from star formation-driven galactic winds, including winds from low-mass satellite galaxies that interact with cosmological filaments. We show that it is necessary to resolve these satellite galaxies and their winds to reproduce the large Lyman limit system covering fractions observed in quasar-mass haloes. Our simulations predict that galaxies occupying dark matter haloes of mass similar to quasars but without a luminous AGN should have Lyman limit system covering fractions comparable to quasars.