ALBERT

Description: For every prime p , we give infinitely many examples of torsors under abelian varieties over Q that are locally trivial but not divisible by p in the Weil–Châtelet group. We also give an example of a locally trivial torsor under an elliptic curve over Q that is not divisible by 4 in the Weil–Châtelet group. This gives a negative answer to a question of Cassels.

Description: We show that at least of the zeros of the Riemann zeta-function are simple, assuming the Riemann hypothesis. This was previously established by Conrey, Ghosh and Gonek [ Proc. London Math. Soc. 76 (1998) 497–522] under the additional assumption of the generalized Lindelöf hypothesis. We are able to remove this hypothesis by careful use of the generalized Vaughan identity.

Description: We construct an infinite family of hyperbolic, homologically thin knots that are not quasi-alternating. To establish the latter, we argue that the branched double-cover of each knot in the family does not bound a negative-definite 4-manifold with trivial first homology and bounded second Betti number. This fact depends in turn on information from the correction terms in Heegaard Floer homology, which we establish by way of a relationship to, and calculation of, the Turaev torsion.

Description: We observe that E -resultant of a very ample rank 2 vector bundle E on a real projective curve (with no real points) is nonnegative when restricted to the space of real sections. Moreover, we show that if E has a section vanishing at exactly two points and the degree d of E satisfies d ( d – 6) ≥ 4( g – 1), then this polynomial cannot be written as a sum of squares.

Description: Let G be one of the Ricci-flat holonomy groups SU( n ), Sp( n ), Spin(7) or G 2 , and M a compact manifold of dimension 2 n , 4 n , 8 or 7, respectively. We prove that the natural map from the moduli space of torsion-free G -structures on M to the moduli space of Ricci-flat metrics is open, and that the image is a smooth manifold. For the exceptional cases G = Spin(7) and G 2 , we extend the result to asymptotically cylindrical manifolds.

Description: We improve the results of Booker and Krishnamurthy ( Compos. Math. 147 (2011) 669–715) by allowing restricted sets of poles among the unramified twists. This allows for a clean statement of the GL(2) converse theorem which includes all cases of Eisenstein series.

Description: Let G be a solvable subgroup of the automorphism group Aut( X ) of a compact Kähler manifold X of complex dimension n , and let N ( G ) be the normal subgroup of G consisting of elements with null entropy. Let us denote by G * the image of G under the natural map from Aut( X ) to GL( V , R ), where V is the Dolbeault cohomology group H 1, 1 ( X , R ). Assume that the Zariski closure of G * in GL( V C ) is connected. The main aim of this paper is to show that, when the rank r ( G ) of the quotient group G / N ( G ) is equal to n – 1 and the identity component of Aut( X ) is trivial, then the normal subgroup N ( G ) of G is finite. This affirmatively answers a question in Invent. Math. posed by D.-Q. Zhang.

Description: N. Ortega, Ashok Kumar, Oscar Resto, O. A. Maslova, Yu. I. Yuzyuk et al. Epitaxial strain is one of the major factors influencing physical properties of artificial superlattice (SL) structures. One way to control the local stress in epitaxial films is altering the lattice parameters by doping. Superlattices of BT/BaSrTiO (BT/BST) with x = (0, 0.3, 0.4, 0.5, 0.6, 0.7, 1) ... [J. Appl. Phys. 114, 104102 (2013)] published Thu Sep 12, 2013.

Description: B. Brennan, R. V. Galatage, K. Thomas, E. Pelucchi, P. K. Hurley et al. InAlAs has the potential to be used as a barrier layer in buried channel quantum well field effect transistor devices due to favorable lattice-matching and carrier confinement properties with InGaAs. Field effect device structures of this nature may also require a high-k oxide deposited on the InAlA ... [J. Appl. Phys. 114, 104103 (2013)] published Thu Sep 12, 2013.

Description: Pooja Srivastava, B. J. Nagare, Dilip G. Kanhere, and Prasenjit Sen First-principles electronic structure calculations are performed for the pure and Co-doped PbPdO using plane wave density functional method using different exchange-correlation functionals. These calculations indicate the 25% Co-doped PbPdO to be a spin gapless semiconductor, as proposed earlier [X. ... [J. Appl. Phys. 114, 103709 (2013)] published Thu Sep 12, 2013.

Description: M. N. Shneider and M. Pekker A non-thermal mechanism of weak microwave field impact on a nerve fiber is proposed. It is shown that in the range of about 30300 GHz, there are strongly pronounced resonances associated with the excitation of ultrasonic vibrations in the membrane as a result of interaction with electromagnetic radi ... [J. Appl. Phys. 114, 104701 (2013)] published Thu Sep 12, 2013.

Description: K. Simeonidis, C. Martinez-Boubeta, Ll. Balcells, C. Monty, G. Stavropoulos et al. Magnetic hyperthermia, an alternative anticancer modality, is influenced by the composition, size, magnetic properties, and degree of aggregation of the corresponding nanoparticle heating agents. Here, we attempt to evaluate the AC magnetic field heating response of Fe-based nanoparticles prepared b ... [J. Appl. Phys. 114, 103904 (2013)] published Thu Sep 12, 2013.

Description: Souheil Mouetsi and Abdelillah El Hdiy The 1/f noise is investigated in an epitaxial AlGaAs/GaAs/AlGaAs heterostructure in the temperature range of [4300 K]. The sample is biased at very low voltage to avoid velocity saturation at low temperature. Hooge parameters are determined at very low frequency assuming the absence of correlation b ... [J. Appl. Phys. 114, 104507 (2013)] published Thu Sep 12, 2013.

Description: V. R. Singh, V. K. Verma, K. Ishigami, G. Shibata, Y. Yamazaki et al. BiFeO (BFO) shows both ferroelectricity and magnetic ordering at room temperature, but its ferromagnetic component, which is due to spin canting, is negligible. Substitution of transition-metal atoms such as Co for Fe is known to enhance the ferromagnetic component in BFO. In order to reveal the ori ... [J. Appl. Phys. 114, 103905 (2013)] published Thu Sep 12, 2013.

Description: N. Kotsina, S. Kaziannis, S. Danakas, and C. Kosmidis We report on the selective ionization of oriented nitrous oxide (NO) molecules in gas phase by the use of an intense asymmetric two-color omega/2omega 40 fs laser field. By means of a time-of-flight mass spectrometer the induced NO mass spectra have been recorded as a function of the relative phase ... [J. Chem. Phys. 139, 104313 (2013)] published Thu Sep 12, 2013.

Description: Bryan Nichols and Vitaly A. Rassolov The electron correlation energy in a chemical system is defined as a difference between the energy of an exact energy for a given Hamiltonian, and a mean-field, or single determinant, approximation to it. A promising way to model electron correlation is through the expectation value of a linear two- ... [J. Chem. Phys. 139, 104111 (2013)] published Thu Sep 12, 2013.

Description: Scott Habershon We introduce a new approach for calculating quantum time-correlation functions and time-dependent expectation values in many-body thermal systems; both electronically adiabatic and non-adiabatic cases can be treated. Our approach uses a path integral simulation to sample an initial thermal density m ... [J. Chem. Phys. 139, 104107 (2013)] published Thu Sep 12, 2013.

Description: Gustavo E. Scuseria, Thomas M. Henderson, and Ireneusz W. Bulik We establish a formal connection between the particle-particle (pp) random phase approximation (RPA) and the ladder channel of the coupled cluster doubles (CCD) equations. The relationship between RPA and CCD is best understood within a Bogoliubov quasiparticle (qp) RPA formalism. This work is a fol ... [J. Chem. Phys. 139, 104113 (2013)] published Thu Sep 12, 2013.

Description: Liangguo He, Chengliang Pan, Hongbo Wang, and Zhihua Feng We develop a novel approach to match harmonics and vibration modes based on the mechanism of multiple tuning fork structure (MTFS), through which it is promising to realize arbitrary periodical vibrations in the resonant state. A prototype three-layer MTFS with first three harmonics is presented to ... [Rev. Sci. Instrum. 84, 096104 (2013)] published Thu Sep 12, 2013.

Description: Yue Lin, Yong Zhang, Zhiqiang Liu, Liqin Su, Jihong Zhang et al. Abstract not available. [Appl. Phys. Lett. 103, 119902 (2013)] published Fri Sep 13, 2013.

Description: D. Haasmann and S. Dimitrijev Based on the insight that the Fermi level in a metaloxidesemiconductor field-effect transistor (MOSFET) channel is set in the conduction band, due to the quantum confinement of the channel electrons, this letter provides an experimental demonstration that the near-interface traps responsible for deg ... [Appl. Phys. Lett. 103, 113506 (2013)] published Fri Sep 13, 2013.

Description: Akira Nagaoka, Hideto Miyake, Tomoyasu Taniyama, Koichi Kakimoto, and Kenji Yoshino Temperature dependent Hall effect measurements from 20 to 300 K have been performed on the quaternary compounds CuZnSnS (CZTS) single crystals. The conductivity mechanisms can be described by a two-path system using Mott variable range hopping and typical thermal activation conduction. The center le ... [Appl. Phys. Lett. 103, 112107 (2013)] published Fri Sep 13, 2013.

Description: Manesh Gopinadhan, Zhen Shao, Yanhui Liu, Sundeep Mukherjee, Ryan C. Sekol et al. We explore finite size effects in the crystallization of a bulk metallic glass with nm-scale dimensions. Nanorods of PtCuNiP are produced by thermoplastic extrusion of supercooled liquid through a nanoporous template. The nanorods exhibit remarkable differences in their crystallization behavior abov ... [Appl. Phys. Lett. 103, 111912 (2013)] published Fri Sep 13, 2013.

Description: A. Bojovschi, J. Scott, and K. Ghorbani An investigation of the interaction between guided electromagnetic waves and carbon fibre reinforced polymer waveguide short circuits is presented. To determine the electromagnetic response of the composite waveguide short circuit, its anisotropic characteristics are considered. The reflection coeff ... [Appl. Phys. Lett. 103, 111910 (2013)] published Fri Sep 13, 2013.

Description: E. Pagounis, R. Chulist, T. Lippmann, M. Laufenberg, and W. Skrotzki Mechanical and synchrotron diffraction experiments were performed to investigate the temperature dependent structural changes in a Ni-Mn-Ga single crystal. The initial sample exhibits a mixture of seven-layered (7M) and non-modulated (NM) martensites at room temperature. Compression along resulted ... [Appl. Phys. Lett. 103, 111911 (2013)] published Fri Sep 13, 2013.

Description: I. Tsioutsios, J. Moser, J. A. Plaza, and A. Bachtold We report on the fabrication and operation of a multi-element vibrational structure consisting of two graphene mechanical resonators coupled by a nanotube beam. The whole structure is suspended. Each graphene resonator is clamped by two metal electrodes. The structure is fabricated using a combinati ... [J. Appl. Phys. 114, 104310 (2013)] published Fri Sep 13, 2013.

Description: Marcela F. Silva, Luiz A. S. de Oliveira, Mariani A. Ciciliati, Lais T. Silva, Bruna S. Pereira et al. FeO nanoparticles with sizes ranging from 15 to 53 nm were synthesized by a modified sol-gel method. Maghemite particles as well as particles with admixture of maghemite and hematite were obtained and characterized by XRD, FTIR, UV-Vis photoacoustic and Mossbauer spectroscopy, TEM, and magnetic meas ... [J. Appl. Phys. 114, 104311 (2013)] published Fri Sep 13, 2013.

Description: Junyan Liu, Alexander Melnikov, and Andreas Mandelis A combined theoretical and experimental approach is reported using spectrally windowed lock-in carrierography imaging (lock-in photoluminescence) under variable illumination intensity to provide quantitative contactless measurements of key electrical parameters (photogenerated current density, J, op ... [J. Appl. Phys. 114, 104509 (2013)] published Fri Sep 13, 2013.

Description: Marcus A. Khuri and Gilbert Weinstein In this paper, we show how a natural coupling of the Dirac equation with the generalized Jang equation leads to a proof of the rigidity statement in the positive mass theorem with charge, without the maximal slicing condition, provided a solution to the coupled system exists. ... [J. Math. Phys. 54, 092501 (2013)] published Fri Sep 13, 2013.

Description: Andre Unterberger We rely on an analysis of initial states of the wave function associated with the simplest relativistic particlethe Weyl neutrinoto construct two series of representations of SL(2,[openface R]), or of the twofold cover of this group, by operators acting on scalar functions defined on the real line. ... [J. Math. Phys. 54, 093509 (2013)] published Fri Sep 13, 2013.

Description: Giorgos Markou and Dimitris Georgakakis In this study, maize silage was anaerobically mono- and co-digested together with low solid swine wastewater in a novel two-state (liquid/solid) anaerobic digester. The special subject of the two-state digester is that operates with both, liquid and solid fractions, which are present in a segregated ... [J. Renewable Sustainable Energy 5, 053107 (2013)] published Fri Sep 13, 2013.

Description: Jung Yup Yang, Young Kyoung Ahn, Pil Ho Huh, Jung Gyu Nam, Min Park et al. After producing crystalline Si (c-Si) solar module, the output power of the c-Si module was decreased compared to the total amount of c-Si cells' power due to the increase of series resistance and the light absorption of the cover glass and encapsulant. We define this power loss as cell to module (C ... [J. Renewable Sustainable Energy 5, 052003 (2013)] published Fri Sep 13, 2013.

Description: Wenjing Qin, Xinrui Xu, Dongyue Liu, Chunyu Ma, Liying Yang et al. ZnO is a promising material used as the electron transport layer in the inverted organic solar cells (IOSCs). However, the electrical or photoelectric properties of ZnO nanoparticles are governed by the surface states of the nanoparticles. Here, we demonstrate that the large number of hydroxyl (-OH) ... [J. Renewable Sustainable Energy 5, 053106 (2013)] published Fri Sep 13, 2013.

Description: Steven J. Beresh, John F. Henfling, Russell W. Spillers, and Brian O. M. Pruett Data have been acquired from a spanwise array of fluctuating wall pressure sensors beneath a wind tunnel wall boundary layer at Mach 2, then invoking Taylor's hypothesis allows the temporal signals to be converted into a spatial map of the wall pressure field. Different frequency ranges of pressure ... [Phys. Fluids 25, 095104 (2013)] published Fri Sep 13, 2013.

Description: Julie Brisset, Daniel Heisselmann, Stefan Kothe, Rene Weidling, and Jurgen Blum The Suborbital Particle Aggregation and Collision Experiment (SPACE) is a novel approach to study the collision properties of submillimeter-sized, highly porous dust aggregates. The experiment was designed, built, and carried out to increase our knowledge about the processes dominating the first pha ... [Rev. Sci. Instrum. 84, 094501 (2013)] published Fri Sep 13, 2013.

Description: The dihedral angle formed at junctions between two plagioclase grains and a grain of augite is only very rarely in textural equilibrium in gabbros from kilometre-scale crustal layered intrusions. The median of a population of these disequilibrium angles, cpp , varies systematically within a single layered intrusion, remaining constant over large stretches of stratigraphy with significant increases and decreases associated with the addition or reduction respectively of the number of phases on the liquidus of the bulk magma. The stepwise changes in cpp are present in the Upper Zone of the Bushveld Complex, the Megacyclic Unit I of the Sept Iles Intrusion, and the Layered Series of the Skaergaard intrusion. The plagioclase-bearing cumulates of Rum have a bimodal distribution of cpp , dependent on whether the cumulus assemblage includes clinopyroxene. The presence of the stepwise changes is independent of the order of arrival of cumulus phases and of the composition of either the cumulus phases or the inferred composition of the interstitial liquid. The only parameter that behaves in an exactly analogous manner to cpp is the rate of change in enthalpy with temperature ( H / T ) during crystallization. Both H / T and cpp increase with the addition of a liquidus phase, and decrease with the removal of a liquidus phase. The replacement of one phase by another has little effect on H / T and no discernible effect on cpp . An increase of H / T results in an increase in the fraction of the total enthalpy budget that is the latent heat of crystallization (the fractional latent heat). It also increases the mass crystallized in each incremental temperature drop (the crystal productivity). These increases of both fractional latent heat and crystal productivity are likely to cause an increase in the time taken to form three-grain junctions in the mush via thermal buffering of a thickened mushy layer. We suggest these are the underlying causes of stepwise increases in cpp . Stepwise changes in the geometry of three-grain junctions in fully solidified gabbros thus provide a clear microstructural marker for the progress of fractionation down the liquid line of descent in layered intrusions.

Description: High-resolution sampling in monogenetic fields has the potential to reveal fine-scale heterogeneity of the mantle, a feature that may be overwhelmed by larger fluxes of magma, or missed by under-sampling. The Quaternary Auckland Volcanic Field (AVF) in northern New Zealand is a basaltic field of 51 small-volume volcanic centres, and is one of the best-sampled examples of a monogenetic volcanic field. We present data for 12 centres in the volcanic field. These show the large compositional variations between volcanoes as well as through single eruptive sequences. Whole-rock compositions range from subalkaline basalt in the larger centres, through alkali basalt to nephelinite in the smallest centres. Fractional crystallization has had a limited effect in many of the centres, but high-pressure clinopyroxene crystallization may have occurred in others. Three end-members are observed in Pb isotope space, indicating that distinct mantle source components are involved in the petrogenesis of the magmas. Whole-rock multi-element patterns show that the larger centres have prominent positive Sr anomalies and lack K anomalies, whereas the smaller centres have prominent negative K anomalies and lack Sr anomalies. The melting parameters and compositions of the sources involved are modelled using trace element ratios and multi-element patterns, and three components are characterized: (1) fertile peridotite with a Pb-isotope composition similar to Pacific mid-ocean ridge basalt; (2) eclogite domains with a HIMU-like isotope composition dispersed within the fertile peridotite; (3) slightly depleted subduction-metasomatized peridotitic lithospheric mantle (containing c . 3% subduction fluids). Modelling shows that melting in the AVF begins in garnet-bearing fertile asthenosphere (with preferential melting of eclogite domains) and that melts are variably diluted by melts of the lithospheric source. The U–Th isotope compositions of the end-members in the AVF show 230 Th excess [( 230 Th/ 232 Th) ratios of 1·11–1·38], with the samples of lower ( 230 Th/ 232 Th) exhibiting higher ( 238 U/ 232 Th), which we attribute to the dilution effect of the melts from the lithospheric mantle source. Modelling reveals a correlation between melting in the asthenosphere, the degree of melting and incorporation of the metasomatized lithospheric mantle source, and the resultant size of the volcanic centre. This suggests that the scale of the eruption may essentially be controlled by asthenospheric mantle dynamics.

Description: The origin of mafic and ultramafic sills exhibiting different whole-rock compositional profiles (e.g. I-, C-, D-, M- and S-shaped profiles) remains controversial. We have addressed this issue by revisiting three ~100 m thick Siberian dolerite sills (Vavukansky, Kuz’movsky and Vilyuysky) that display remarkable internal differentiation. The Vavukansky sill has an M-shaped profile with prominent basal and top reversals showing inward increases in whole-rock MgO, Mg-number [100Mg/(Mg + Fe)] and normative An content [100An/(An + Ab)], followed by the Layered and Upper Border Series with inward decreases in these indices. The Kuz’movsky and Vilyuysky sills both show S-shaped profiles similar to the Vavukansky sill, but lack a top reversal. These whole-rock M- and S-shaped profiles are accompanied by similar profiles in mineral compositions. Plagioclase and, to a lesser extent, olivine show systematic inward increases in An content and Mg-number, respectively, across basal and top reversals. These compositional trends are followed by inward decreases in these ratios in the interiors of the Vavukansky and Kuz’movsky sills. Currently accepted models attribute whole-rock M- and S-shaped compositional profiles to crystal settling, compositional convection or compaction operating in closed systems. Our observations challenge these traditional interpretations because variations in mineral compositions observed in marginal reversals cannot result from closed-system fractionation. We suggest instead that initially the sills evolved as open systems that were slowly inflated by magmas that became gradually more primitive with time. The inflation was accompanied by in situ crystallization that preserved the preceding fractionation history of the injected magmas by forming basal and top reversals with minerals becoming more primitive inwards. This process culminated with rapid inflation of the sills to their current size owing to a major influx of primitive magma. Subsequently, magma flow through the sills ceased and they evolved as closed systems by fractional crystallization. This resulted in the Layered and Upper Border Series with minerals becoming more evolved inwards. This model can be extended to explain other compositional profiles and petrological features in mafic and ultramafic sills.

Description: The genomes of related species contain valuable information on the history of the considered taxa. Great apes in particular exhibit variation of evolutionary patterns along their genomes. However, the great ape data also bring new challenges, such as the presence of incomplete lineage sorting and ancestral shared polymorphisms. Previous methods for genome-scale analysis are restricted to very few individuals or cannot disentangle the contribution of mutation rates and fixation biases. This represents a limitation both for the understanding of these forces as well as for the detection of regions affected by selection. Here, we present a new model designed to estimate mutation rates and fixation biases from genetic variation within and between species. We relax the assumption of instantaneous substitutions, modeling substitutions as mutational events followed by a gradual fixation. Hence, we straightforwardly account for shared ancestral polymorphisms and incomplete lineage sorting. We analyze genome-wide synonymous site alignments of human, chimpanzee, and two orangutan species. From each taxon, we include data from several individuals. We estimate mutation rates and GC-biased gene conversion intensity. We find that both mutation rates and biased gene conversion vary with GC content. We also find lineage-specific differences, with weaker fixation biases in orangutan species, suggesting a reduced historical effective population size. Finally, our results are consistent with directional selection acting on coding sequences in relation to exonic splicing enhancers.

Description: J. Qi, L. Yan, H. D. Zhou, J.-X. Zhu, S. A. Trugman et al. Abstract not available. [Appl. Phys. Lett. 103, 129901 (2013)] published Mon Sep 16, 2013.

Description: Bao Q. Ta, Einar Halvorsen, Nils Hoivik, and Knut E. Aasmundtveit Controlling the growth orientation of carbon nanotubes (CNTs) is a topic of great importance in the integration of CNTs into micro/nanosystems. The electric field has been exploited to control the growth orientation of CNTs. In this letter, the diameter dependency of the effect of an electric field ... [Appl. Phys. Lett. 103, 123102 (2013)] published Mon Sep 16, 2013.

Description: Subhamoy Ghatak and Arindam Ghosh We present temperature dependent IV measurements of short channel MoS field effect devices at high source-drain bias. We find that, although the IV characteristics are ohmic at low bias, the conduction becomes space charge limited at high V, and existence of an exponential distribution of trap state ... [Appl. Phys. Lett. 103, 122103 (2013)] published Mon Sep 16, 2013.

Description: T. Hirano, K. Okada, J. Hirokawa, and M. Ando A 60 Gigahertz (GHz) on-chip differential-feed dipole antenna integrated in a 65 nm complementary metal oxide semiconductor (CMOS) technology is investigated by simulation and measurement. It was found that it is important to model lossy thin well layer on the surface of CMOS substrate. Simulated fr ... [Appl. Phys. Lett. 103, 122101 (2013)] published Mon Sep 16, 2013.

Description: Ian P. Seetoh, Chew Beng Soh, Li Zhang, Kar Hoo Patrick Tung, Eugene A. Fitzgerald et al. InN was grown over nanoporous GaN by metal-organic chemical vapor deposition. Additional free surfaces in the numerous GaN nanopores reduced the surface energy and encouraged extensive nucleation and uniform growth of InN nanoislands. Conversely, coarse and poorly distributed InN islands grew on pla ... [Appl. Phys. Lett. 103, 121903 (2013)] published Mon Sep 16, 2013.

Description: Xiang Yan, Rui Zhu, Guoliang Huang, and Fuh-Gwo Yuan Bonding a two-dimensional planar array of small lead discs on an aluminum plate with silicone rubber is shown numerically to focus low-frequency flexural guided waves. The effective mass density profile of this type of elastic metamaterials (EMMs), perpendicular to wave propagation direction, is car ... [Appl. Phys. Lett. 103, 121901 (2013)] published Mon Sep 16, 2013.

Description: Andrew J. Martin, Allen H. Hunter, Timothy W. Saucer, Vanessa Sih, Emmanuelle A. Marquis et al. Different modes of intermixing are observed in GaSb/GaAs layers via atom probe tomography. The intermixing length scale for quantum wells of varying thickness is on the order of a monolayer, but three times longer for the wetting layer of a quantum dot structure. The former arises from segregation o ... [Appl. Phys. Lett. 103, 122102 (2013)] published Mon Sep 16, 2013.

Description: Leijun Yin, David Shelhammer, Gejian Zhao, Zhicheng Liu, and C. Z. Ning Increasing erbium concentration while minimizing the reduction of photoluminescence is an important task for achieving erbium-based high-gain materials for integrated photonics applications. Here, we demonstrate a strategy of controlled variation of Erbium density in the growth of erbium yttrium chl ... [Appl. Phys. Lett. 103, 121902 (2013)] published Mon Sep 16, 2013.

Description: Genetic control of male or female gonad development displays between different groups of organisms a remarkable diversity of "master sex-determining genes" at the top of the genetic hierarchies, whereas downstream components surprisingly appear to be evolutionarily more conserved. Without much further studies, conservation of sequence has been equalized to conservation of function. We have used the medaka fish to investigate the generality of this paradigm. In medaka, the master male sex-determining gene is dmrt1bY , a highly conserved downstream regulator of sex determination in vertebrates. To understand its function in orchestrating the complex gene regulatory network, we have identified targets genes and regulated pathways of Dmrt1bY. Monitoring gene expression and interactions by transgenic fluorescent reporter fish lines, in vivo tissue-chromatin immunoprecipitation and in vitro gene regulation assays revealed concordance but also major discrepancies between mammals and medaka, notably amongst spatial, temporal expression patterns and regulations of the canonical Hedgehog and R-spondin/Wnt/Follistatin signaling pathways. Examination of Foxl2 protein distribution in the medaka ovary defined a new subpopulation of theca cells, where ovarian-type aromatase transcriptional regulation appears to be independent of Foxl2. In summary, these data show that the regulation of the downstream regulatory network of sex determination is less conserved than previously thought.

Description: M. M. Uddin, H. W. Liu, K. F. Yang, K. Nagase, K. Sekine et al. We investigated the gate control of a two-dimensional electron gas (2DEG) confined to InSb quantum wells with an AlO gate dielectric formed by atomic layer deposition on a surface layer of AlInSb or InSb. The wider bandgap of AlInSb compared to InSb resulted in a linear, sharp, and non-hysteretic re ... [Appl. Phys. Lett. 103, 123502 (2013)] published Mon Sep 16, 2013.

Description: Yanan Wang, Zhihua Su, Wei Wu, Shu Nie, Nan Xie et al. We report the synthesis and systematic Raman study of twisted bilayer graphene (tBLG) with rotation angles from below 10 degrees to nearly 30 degrees . Chemical vapor deposition was used to grow hexagon-shaped tBLG with a rotation angle that can be conveniently determined by relative edge misalignm ... [Appl. Phys. Lett. 103, 123101 (2013)] published Mon Sep 16, 2013.

Description: E. Koren, E. Sutter, S. Bliznakov, F. Ivars-Barcelo, and P. Sutter We introduce a method for isolating graphene grown on epitaxial Ru(0001)/alpha-AlO. The strong graphene/Ru(0001) coupling is weakened by electrochemically driven intercalation of hydrogen underpotentially deposited in aqueous KOH solution, which allows the penetration of water molecules at the graph ... [Appl. Phys. Lett. 103, 121602 (2013)] published Mon Sep 16, 2013.

Description: Vineeth Nair and R. I. Sujith In this paper, we show how the phenomenon of intermittency observed in systems with turbulent flow-sound interaction is related to the formation of homoclinic orbits in the phase space. Such orbits that emerge via the intersection of the stable and unstable manifold of an equilibrium configuration r ... [Chaos 23, 033136 (2013)] published Mon Sep 16, 2013.

Description: Po-Liang Liu and Jia-Yang Hong We present ab initio calculations to find the migration pathways of the hydrogen atom through Stone-Wales defects into the inside of the double-shell fullerene. We report that the most favorable pathway consists of the tunneling pathway through Stone-Wales defects on the double-shell C/C fullerene. ... [J. Appl. Phys. 114, 114301 (2013)] published Mon Sep 16, 2013.

Description: Changsheng Song, Jiqing Wang, Weixian Lin, Huibing Mao, Qiang Zhao et al. Using first principles calculation based on density-functional theory, we adopted internal and external two mechanisms to manipulate the band structures of wurtzite and zinc-blende GaAs/InAs-core-shell nanowires (NWs) along the [0001] and [111] directions, respectively. Variational geometry size and ... [J. Appl. Phys. 114, 113704 (2013)] published Mon Sep 16, 2013.

Description: B. A. Mason, L. J. Groven, and S. F. Son Metal-based reactive composites have great potential as energetic materials due to their high energy densities and potential uses as structural energetic materials and enhanced blast materials however these materials can be difficult to ignite with typical particle size ranges. Recent work has shown ... [J. Appl. Phys. 114, 113501 (2013)] published Mon Sep 16, 2013.

Description: L. Redaelli, H. Wenzel, M. Martens, S. Einfeldt, M. Kneissl et al. The threshold current density of narrow (1.5 [mu]m) ridge waveguide (In,Al)GaN based laser diodes is found to strongly depend on the ridge etch depth. By solving the complex-value two-dimensional waveguide equation, it is shown that, for shallow-ridge devices with a small built-in index step, the de ... [J. Appl. Phys. 114, 113102 (2013)] published Mon Sep 16, 2013.

Description: A. T. Brant, N. C. Giles, Shan Yang (杨山) , M. A. R. Sarker, S. Watauchi et al. Results from electron paramagnetic resonance (EPR) and electron-nuclear double resonance (ENDOR) experiments are used to establish the model for the ground state of the singly ionized oxygen vacancy in the interior of bulk rutile TiO crystals. Hyperfine from Ti and Ti nuclei show that the unpaired e ... [J. Appl. Phys. 114, 113702 (2013)] published Mon Sep 16, 2013.

Description: V. Hari Babu, R. K. Govind, K.-M. Schindler, M. Welke, and R. Denecke The growth and magnetic properties of ultrathin iron oxide films on BaTiO(001) substrate have been studied by low energy electron diffraction, x-ray absorption spectroscopy (XAS), x-ray magnetic circular dichroism (XMCD), and magneto-optic Kerr effect experiments. The iron oxide films were prepared ... [J. Appl. Phys. 114, 113901 (2013)] published Mon Sep 16, 2013.

Description: Mengmeng Guan, Xiaoru Zhao, Libing Duan, Mengmeng Cao, Wenrui Guo et al. SnO nanoparticles, nanoflowers, and nanorods of highly crystalline were synthesized via a simple hydrothermal method. The size and morphology of the SnO nanostructures could be controlled by varying the NaOH concentration of the precursor solutions. The SnO structures appeared to be sphere-like nano ... [J. Appl. Phys. 114, 114302 (2013)] published Mon Sep 16, 2013.

Description: Marina Prenzel, Annika Kortmann, Adrian Stein, Achim von Keudell, Farwah Nahif et al. AlO thin films have been deposited at substrate temperatures between 500 degrees C and 600 degrees C by reactive magnetron sputtering using an additional arbitrary substrate bias to tailor the energy distribution of the incident ions. The films were characterized by X-ray diffraction and Fourier t ... [J. Appl. Phys. 114, 113301 (2013)] published Mon Sep 16, 2013.

Description: N. Izyumskaya, F. Zhang, S. Okur, T. Selden, V. Avrutin et al. Formation of defects in semipolar (1[overline 1]01)-oriented GaN layers grown by metal-organic chemical vapor deposition on patterned Si (001) substrates and their effects on optical properties were investigated by steady-state and time-resolved photoluminescence (PL) and spectrally and spatially re ... [J. Appl. Phys. 114, 113502 (2013)] published Mon Sep 16, 2013.

Description: Dong Hun Kim, Gerald F. Dionne, and C. A. Ross The structure and magnetic behavior of Cu-substituted SrTiO (STCu) thin films with ~22% Cu on the Ti sites, grown on CeO/yttria stabilized zirconia buffered (001) Si substrates were investigated. STCu films grew with (110) orientation or with a mixed (001)+(110) orientation and were under in-plane c ... [J. Appl. Phys. 114, 113902 (2013)] published Mon Sep 16, 2013.

Description: Masashi Tsuda, Takeshi Wada, and Hidemi Kato The transition behavior from a TiCu alloy to nanoporous alpha-Ti, the kinetics of the dealloying reaction, and the coarsening of nanoporous alpha-Ti were studied, and the mechanism of dealloying with a metallic melt was investigated. When a TiCu alloy disk was immersed in a Mg melt, the Cu content d ... [J. Appl. Phys. 114, 113503 (2013)] published Mon Sep 16, 2013.

Description: Peter Foldesy Current biased photoresponse model of long channel field-effect transistor (FET) detectors is introduced to describe the low frequency behavior in complex circuit environment. The model is applicable in all FET working regions, including subthreshold, linear, saturated modes, includes bulk potential ... [J. Appl. Phys. 114, 114501 (2013)] published Mon Sep 16, 2013.

Description: Yanping Wang, Jiangshan Chen, Lisong Dong, and Dongge Ma The electron mobilities of tris(8-hydroxy-quinolinato) aluminum (Alq) thin films at various thicknesses (70280 nm) have been determined by using admittance spectroscopy measurements. Our results show that the electric field dependence of electron mobilities exhibits different behaviors at different ... [J. Appl. Phys. 114, 113703 (2013)] published Mon Sep 16, 2013.

Description: S. Hosseini Vajargah, S. Ghanad-Tavakoli, J. S. Preston, R. N. Kleiman, and G. A. Botton The initial growth stages of GaSb epilayers on Si substrates and the role of the AlSb buffer layer were studied by high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). Heteroepitaxy of GaSb and AlSb on Si both occur by Volmer-Weber (i.e., island mode) growth. However ... [J. Appl. Phys. 114, 113101 (2013)] published Mon Sep 16, 2013.

Description: C. H. Yang, Y. Luo, Z. S. Liu, and J. J. Jiang In this article, we present a theoretical study of the optical spectrum induced by electron-electron interaction in graphene, which can be compared with the case in a conventional two-dimensional electron gas (2DEG). It is found that in sharp contrast to the conventional 2DEG, two intra- and inter-b ... [J. Appl. Phys. 114, 113701 (2013)] published Mon Sep 16, 2013.

Description: Linsen Zhou, Guang-Shuang-Mu Lin, and Daiqian Xie State-to-state photodissociation dynamics of DO in the B band has been investigated using the recently developed diabatic potential energy surfaces. Quantum dynamical calculations including the electronic X-tilde and B-tilde states were carried out using a Chebyshev real wave packet method. The nona ... [J. Chem. Phys. 139, 114303 (2013)] published Mon Sep 16, 2013.

Description: M. J. Gillan, D. Alfe, P. J. Bygrave, C. R. Taylor, and F. R. Manby We show how an embedded many-body expansion (EMBE) can be used to calculate accurate ab initio energies of water clusters and ice structures using wavefunction-based methods. We use the EMBE described recently by Bygrave et al. [J. Chem. Phys. 137, 164102 (2012)], in which the terms in the expansion ... [J. Chem. Phys. 139, 114101 (2013)] published Mon Sep 16, 2013.

Description: Yu-Qi Li, Xiao-Yin Pan, and Viraht Sahni The many-body wave function of a system of interacting particles confined by a time-dependent harmonic potential and perturbed by a time-dependent spatially homogeneous electric field is derived via the Feynman path-integral method. The wave function is comprised of a phase factor times the solution ... [J. Chem. Phys. 139, 114301 (2013)] published Mon Sep 16, 2013.

Description: Marta Enciso and Antonio Rey We explore the applicability of a single-bead coarse-grained molecular model to describe the competition between protein folding and aggregation. We have designed very simple and regular sequences, based on our previous studies on peptide aggregation, that successfully fold into the three main prote ... [J. Chem. Phys. 139, 115101 (2013)] published Mon Sep 16, 2013.

Description: Evangelos Miliordos, Edoardo Apra, and Sotiris S. Xantheas We report the first optimum geometries and harmonic vibrational frequencies for the ring pentamer and several water hexamer (prism, cage, cyclic and two book) at the coupled-cluster including single, double, and full perturbative triple excitations (CCSD(T))/aug-cc-pVDZ level of theory. All five exa ... [J. Chem. Phys. 139, 114302 (2013)] published Mon Sep 16, 2013.

Description: We present measurements of higher order clustering of galaxies in the latest release of the Canada–France–Hawaii Telescope Legacy Survey (CFHTLS)-Wide. We construct a series of volume-limited sample of galaxies containing more than one million galaxies over the redshift range 0.2 〈  z  〈 1 in the four independent fields of the CFHTLS-Wide. Using a counts-in-cells technique we measure the variance ${\bar{\xi }}_2$ and the hierarchical moments $S_{n}= {{\bar{\xi }}_n / {\bar{\xi }}_2^{n-1}}$ (3 ≤  n  ≤ 5) as a function of redshift and angular scale. We find that the measured field-to-field scatter in our estimators is in excellent agreement with analytical predictions. At small scales, corresponding to the highly non-linear regime, we find tentative evidence at the 1 level that the hierarchical moments increase with redshift. At large scales, corresponding to the weakly non-linear regime, our measurements are marginally consistent with perturbation theory predictions for standard cold dark matter cosmology using a simple linear bias. The predictions of perturbation theory tend to slightly overestimate our measurements, which may be a signature of non-linear bias.

Description: We estimate cosmic microwave background (CMB) polarization power spectra and temperature–polarization cross-spectra, from the 9-year data of the Wilkinson Microwave Anisotropy Probe ( WMAP ). Foreground cleaning is implemented using minimum variance linear combinations of the coefficients of needlet decompositions of sky maps for all WMAP channels, to produce maps for CMB temperature anisotropies ( T -mode) and polarization ( E and B -modes), for nine different years of observation. The final power spectra are computed from averages of all possible cross-year power spectra obtained using foreground-cleaned maps for the different years. Our analysis technique yields a measurement of the EE spectrum that is in excellent agreement with theoretical expectations from the current cosmological model. By comparison, the publicly available WMAP EE power spectrum is higher on average (and significantly higher than the predicted EE spectrum from the current best fit) at scales larger than about a degree, an excess that is not confirmed by our analysis. Our TE and TB measurements are in good agreement overall with the WMAP ones and are compatible with the theoretical expectations, although a few data points are off by a few standard deviations, and yield a reduced 2 somewhat above expectation. As predicted for a standard cosmological model with low tensor-to-scalar ratio, the EB and BB power spectra obtained in our analysis are compatible with zero.

Description: We present optical integral field unit observations of two gas pillars surrounding the Galactic young massive star cluster NGC 3603. The high S/N and spectral resolution of these data have allowed us to accurately quantify the Hα, [N ii ] and [S ii ] emission line shapes, and we find a mixture of broad (FWHM ~ 70–100 km s –1 ) and narrow (〈50 km s –1 ) components. The broad components are found close to the edges of both pillars, suggesting that they originate in turbulent mixing layers (TMLs) driven by the effect of the star cluster wind. Both pillars exhibit surprisingly high ionized gas densities of 〉10 000 cm –3 . In one pillar we found that these high densities are only found in the narrow component, implying that they must originate from deeper within the pillar than the broad component. From this, together with our kinematical data, we conclude that the narrow component traces a photoevaporation flow, and that the TML forms at the interface with the hot wind. On the pillar surfaces, we find a consistent offset in radial velocity between the narrow (brighter) components of Hα and [N ii ] of ~5–8 km s –1 , for which we were unable to find a satisfactory explanation. We urge the theoretical community to simulate mechanical and radiative cloud interactions in more detail to address the many unanswered questions raised by this study.

Description: By exploiting the data base of early-type galaxy (ETG) members of the WINGS survey of nearby clusters, we address here the long debated question of the origin and shape of the Fundamental Plane (FP). Our data suggest that different physical mechanisms concur in shaping and ‘tilting’ the FP with respect to the virial plane (VP) expectation. In particular, a ‘hybrid solution’ in which the structure of galaxies and their stellar population are the main contributors to the FP tilt seems to be favoured. We find that the bulk of the tilt should be attributed to structural non-homology, while stellar population effects play an important but less crucial role. In addition, our data indicate that the differential FP tilt between the V and K band is due to a sort of entanglement between structural and stellar population effects, for which the inward steepening of colour profiles ( V  –  K ) tends to increase at increasing the stellar mass of ETGs. The same kind of analysis applied to the ATLAS 3 D and Sloan Digital Sky Survey (SDSS) data in common with WINGS ( WSDSS throughout the paper) confirms our results, the only remarkable difference being the less important role that our data attribute to the stellar mass-to-light-ratio (stellar populations) in determining the FP tilt . The ATLAS 3 D data also suggest that the FP tilt depends as well on the dark matter (DM) fraction and on the rotational contribution to the kinetic energy ( V rot /), thus again pointing towards the above-mentioned ‘hybrid solution’. We show that the global properties of the FP, i.e. its tilt and tightness, can be understood in terms of the underlying correlation among mass, structure and stellar population of ETGs, for which, at increasing the stellar mass, ETGs become (on average) ‘older’ and more centrally concentrated. Finally, we show that a Malmquist-like selection effect may mimic a differential evolution of the mass-to-light ratio for galaxies of different masses. This should be taken into account in the studies investigating the amount of the so-called ‘downsizing’ phenomenon.

Description: I present a new algorithm, Curved-sky grAvitational Lensing for Cosmological Light conE simulatioNS ( calclens ), for efficiently computing weak gravitational lensing shear signals from large N -body light cone simulations over a curved sky. This new algorithm properly accounts for the sky curvature and boundary conditions, is able to produce redshift-dependent shear signals including corrections to the Born approximation by using multiple-plane ray tracing and properly computes the lensed images of source galaxies in the light cone. The key feature of this algorithm is a new, computationally efficient Poisson solver for the sphere that combines spherical harmonic transform and multigrid methods. As a result, large areas of sky (~10 000 square degrees) can be ray traced efficiently at high resolution using only a few hundred cores. Using this new algorithm and curved-sky calculations that only use a slower but more accurate spherical harmonic transform Poisson solver, I study the convergence, shear E-mode, shear B-mode and rotation mode power spectra. Employing full-sky E/B-mode decompositions, I confirm that the numerically computed shear B-mode and rotation mode power spectra are equal at high accuracy (1 per cent) as expected from perturbation theory up to second order. Coupled with realistic galaxy populations placed in large N -body light cone simulations, this new algorithm is ideally suited for the construction of synthetic weak lensing shear catalogues to be used to test for systematic effects in data analysis procedures for upcoming large-area sky surveys. The implementation presented in this work, written in c and employing widely available software libraries to maintain portability, is publicly available at http://code.google.com/p/calclens .

Description: Quasar accretion disc winds observed via broad absorption lines (BALs) in the UV produce strong continuous absorption in X-rays. The X-ray absorber is believed to serve critically as a radiative shield to keep the outflow ionizations low enough for radiative driving. However, previous studies have shown that ‘mini-BAL’ and narrow absorption line (NAL) outflows have dramatically less X-ray absorption than BALs. Here, we examine X-ray and rest-frame UV spectra of eight mini-BAL quasars with outflow speeds in the range 0.1–0.2c to test the hypothesis that these extreme speeds require a strong shield. We find that the X-ray absorption is weak or moderate, with neutral-equivalent column densities N H  〈 few 10 22 cm –2 , consistent with mini-BALs at lower speeds. We use photoionization models to show that the amount of shielding consistent with our data is too weak to control the outflow ionizations and, therefore, it is not important for the acceleration. Shielding in complex geometries also seems unlikely because the alleged shield would need to extinguish the ionizing far-UV flux while avoiding detection in X-rays and the near-UV. We argue that the outflow ionizations are kept moderate, instead, by high gas densities in small clouds. If the mini-BALs form at radial distances of the order of R ~ 2 pc from the central quasar (broadly consistent with theoretical models and with the mini-BAL variabilities observed here and in previous work), and the total column densities in the mini-BAL gas are N H 10 21 cm –2 , then the total radial extent of outflow clouds is only R clouds 3 x 10 13 cm in cases of no/weak shielding or R clouds 3 x 10 14 cm behind the maximum shield allowed by our data. This implies radial filling factors R clouds / R 5 x 10 – 6 or 5 x 10 – 5 for the unshielded or maximally shielded cases, respectively. Compared to the transverse sizes 8 x 10 15 cm (based on measured line depths), the outflows have shapes like thin ‘pancakes’ viewed face-on, or they occupy larger volumes like a spray of many dense clouds with a small volume filling factor. These results favour models with magnetic confinement in magnetic disc winds. To the extent that BALs, mini-BALs and NALs probe the same general outflow phenomenon, our result for dense substructures should apply to all three outflow types.

Description: The estimated stellar masses of galaxies are widely used to characterize how the galaxy population evolves over cosmic time. If stellar masses can be estimated in a robust manner, free from any bias, global diagnostics such as the stellar mass function can be used to constrain the physics of galaxy formation. We explore how galaxy stellar masses, estimated by fitting broad-band spectral energy distributions (SEDs) with stellar population models, can be biased as a result of commonly adopted assumptions for the star formation and chemical enrichment histories, recycled fractions and dust attenuation curves of galaxies. We apply the observational technique of broad-band SED fitting to model galaxy SEDs calculated by the theoretical galaxy formation model GALFORM, isolating the effect of each of these assumptions. We find that, averaged over the entire galaxy population, the common assumption of exponentially declining star formation histories does not, by itself, adversely affect stellar mass estimation. However, we also show that this result does not hold when considering galaxies that have undergone a recent burst of star formation. We show that fixing the metallicity in SED fitting or using sparsely sampled metallicity grids can introduce mass-dependent systematics into stellar mass estimates. We find that the common assumption of a star–dust geometry corresponding to a uniform foreground dust screen can cause the stellar masses of dusty model galaxies to be significantly underestimated. Finally, we show that stellar mass functions recovered by applying SED fitting to model galaxies at high redshift can differ significantly in both shape and normalization from the intrinsic mass functions predicted by a given model. In particular, the effects of dust can reduce the normalization at the high-mass end by up to 0.6 dex in some cases. Given these differences, our methodology of using stellar masses estimated from model galaxy SEDs offers a new, self-consistent way to compare model predictions with observations. We conclude that great care should be taken when comparing theoretical galaxy formation models to observational results based on the estimated stellar masses of high-redshift galaxies.

Description: We analyse the 2D correlation function of the Sloan Digital Sky Survey-III Baryon Oscillation Spectroscopic Survey (BOSS) CMASS sample of massive galaxies of the ninth data release to measure cosmic expansion H and the angular diameter distance D A at a mean redshift of 〈 z 〉 = 0.57. We apply, for the first time, a new correlation function technique called clustering wedges μ ( s ). Using a physically motivated model, the anisotropic baryonic acoustic feature in the galaxy sample is detected at a significance level of 4.7 compared to a featureless model. The baryonic acoustic feature is used to obtain model-independent constraints cz / H / r s = 12.28 ± 0.82 (6.7 percent accuracy) and D A / r s =  9.05 ± 0.27 (3.0 per cent) with a correlation coefficient of –0.5, where r s is the sound horizon scale at the end of the baryonic drag era. We conduct thorough tests on the data and 600 simulated realizations, finding robustness of the results regardless of the details of the analysis method. Combining this with r s constraints from the cosmic microwave background, we obtain H (0.57) = 90.8 ± 6.2 km s –1 Mpc –1 and D A (0.57) = 1386 ± 45 Mpc. We use simulations to forecast results of the final BOSS CMASS data set. We apply the reconstruction technique on the simulations demonstrating that the sharpening of the anisotropic baryonic acoustic feature should improve the detection as well as tighten constraints of H and D A by ~30 per cent on average.

Description: We present an analysis of Chandra archival, pre-explosion data of the positions of three nearby (〈25 Mpc) Type Ia supernovae, SN2011iv, SN2012cu and SN2012fr. No sources corresponding to the progenitors were found in any of the observations. Combining all sources with well-defined backgrounds does not reveal any evidence for X-ray emission from the progenitors either. We calculated upper limits on the bolometric luminosities of the progenitors, under the assumption that they were black bodies with effective temperatures between 30 and 150 eV, corresponding to ‘canonical’ supersoft X-ray sources. The upper limits of SN2012fr straddle the Eddington luminosity of canonical supersoft sources, but fainter canonical supersoft sources cannot be ruled out by this study. We also compare our upper limits with known compact binary supersoft X-ray sources. This study is a continuation of the campaign to directly detect or constrain the X-ray characteristics of pre-explosion observations of nearby Type Ia supernova progenitors; with the results reported in Nielsen, Voss & Nelemans (see reference in Introduction), the number of nearby Type Ia supernovae for which pre-explosion images are available in the Chandra archive is now 13 and counting.

Description: In this work, we report the Photodetector Array Camera and Spectrometer (PACS) 100 μm/160 μm detections of a sample of 42 GALEX -selected and far-infrared (FIR)-detected Lyman break galaxies (LBGs) at z  ~ 1 located in the Cosmic Evolution Survey (COSMOS) field and analyse their ultraviolet (UV) to FIR properties. The detection of these LBGs in the FIR indicates that they have a dust content high enough so that its emission can be directly detected. According to a spectral energy distribution (SED) fitting with stellar population templates to their UV-to-near-IR observed photometry, PACS-detected LBGs tend to be bigger ( R eff  ~ 4.1 kpc), more massive [log ( M * /M ) ~ 10.7], dustier [ E s ( B  –  V ) ~ 0.40], redder in the UV continuum (β ~ –0.60) and UV-brighter [log ( L UV /L ) ~ 10.1] than PACS-undetected LBGs. PACS-detected LBGs at z  ~ 1 are mostly disc-like galaxies and are located over the green valley and red sequence of the colour–magnitude diagram of galaxies at their redshift. By using their UV and IR emission, we find that PACS-detected LBGs tend to be less dusty and have slightly higher total star formation rates (SFRs) than other PACS-detected UV-selected galaxies within the same redshift range. As a consequence of the selection effect due to the depth of the FIR observations employed, all our PACS-detected LBGs have total IR luminosities, L IR , higher than 10 11 L and thus are luminous IR galaxies. However, none of the PACS-detected LBGs are in the ultra-luminous IR galaxy (ULIRG) regime, L IR  ≥ 10 12 L , where the FIR observations are complete. The finding of ULIRGs-LBGs at higher redshifts ( z  ~ 3) suggests an evolution of the FIR emission of LBGs with cosmic time. In an IRX–β diagram, PACS-detected LBGs at z  ~ 1 tend to be located around the relation for local starburst similarly to other UV-selected PACS-detected galaxies at the same redshift. Consequently, the dust-correction factors obtained with their UV continuum slope allow us to determine their total SFR, unlike at higher redshifts. However, the dust attenuation derived from UV to NIR SED fitting overestimates the total SFR for most of our PACS-detected LBGs in an age-dependent way: the overestimation factor is higher in younger galaxies. This is likely due to the typical degeneracy between dust attenuation and age in the SED fitting with synthetic templates and highlights the importance of the FIR measurements in the analysis of star-forming galaxies at intermediate redshifts.

Description: We study 23 previously published Kepler targets to perform a consistent grid-based Bayesian asteroseismic analysis and compare our results to those obtained via the Asteroseismic Modelling Portal. We find differences in the derived stellar parameters of many targets and their uncertainties. While some of these differences can be attributed to systematic effects between stellar evolutionary models, we show that the different methodologies deliver incompatible uncertainties for some parameters. Using non-adiabatic models and our capability to measure surface effects, we also investigate the dependency of these surface effects on the stellar parameters. Our results suggest a dependence of the magnitude of the surface effect on the mixing length parameter which also, but only minimally, affects the determination of stellar parameters. While some stars in our sample show no surface effect at all, the most significant surface effects are found for stars that are close to the Sun's position in the Hertzsprung–Russell diagram.

Description: We present evidence for a strong relationship between galaxy size and environment for the quiescent population in the redshift range 1 〈  z  〈 2. Environments were measured using projected galaxy overdensities on a scale of 400 kpc, as determined from ~96 000 K -band-selected galaxies from the UKIDSS Ultra Deep Survey (UDS). Sizes were determined from ground-based K -band imaging, calibrated using space-based CANDELS HST observations in the centre of the UDS field, with photometric redshifts and stellar masses derived from 11-band photometric fitting. From the resulting size–mass relation, we confirm that quiescent galaxies at a given stellar mass were typically ~50 per cent smaller at z  ~ 1.4 compared to the present day. At a given epoch, however, we find that passive galaxies in denser environments are on average significantly larger at a given stellar mass. The most massive quiescent galaxies ( M *  〉 2 10 11  M ) at z  〉 1 are typically 50 per cent larger in the highest density environments compared to those in the lowest density environments. Using Monte Carlo simulations, we reject the null hypothesis that the size–mass relation is independent of environment at a significance 〉4.8 for the redshift range 1 〈  z  〈 2. In contrast, the evidence for a relationship between size and environment is much weaker for star-forming galaxies.

Description: We present the results from the Very Large Array radio continuum total power and polarized intensity observations of Stephan's Quintet at 1.43 and 4.86 GHz, along with complementary 4.85- and 8.35-GHz Effelsberg observations. Our study shows a large envelope of radio emission encompassing all the member galaxies and hence a large volume of intergalactic matter. Infall of the galaxy NGC 7318B produces a ridge of intergalactic, polarized emission, for which the magnetic field strength has been estimated as 11.0 ± 2.2 μG, with an ordered component of 2.6 ± 0.8 μG. The energy density of the field within the ridge area is of the same order as estimates of the thermal component, implying that the magnetic field has a significant role in the dynamics of the intergalactic matter. We also report that the tidal dwarf galaxy candidate SQ-B possesses a strong and highly anisotropic magnetic field, with a total strength equal to 6.5 ± 1.9 μG and an ordered component reaching 3.5 ± 1.2 μG, which is comparable to that found in normal-sized galaxies.

Description: We present a simple and efficient phenomenological model for the two-dimensional two-point galaxy correlation function that works well over a wide range of scales, from large scales down to scales as small as 25 h –1 Mpc. Our model incorporates non-linear effects and a scale-dependent galaxy bias on small scales, and it allows the redshift-space distortions to be scale and direction dependent. We validate our model using LasDamas mock catalogues and apply it to the Sloan Digital Sky Survey (SDSS) Data Release Seven (DR7) luminous red galaxies (LRGs). Using only the monopole and quadrupole of the correlation function measured from the SDSS DR7 LRGs, we obtain improved measurements H ( z ) r s ( z d )/ c  = 0.0433 ± 0.0042, D A ( z )/ r s ( z d ) = 6.59 ± 0.46 and f ( z ) 8 ( z ) = 0.429 ± 0.089 at z  = 0.35, using the scale range 25 〈  s  〈 120 h –1 Mpc. We expect our results and model to be useful in tightening dark energy and gravity constraints from the full analysis of current and future galaxy clustering data.

Description: We study the formation and evolution of filamentary configurations of dark matter haloes in voids. Our investigation uses the high-resolution cold dark matter simulation CosmoGrid to look for void systems resembling the VGS_31 elongated system of three interacting galaxies that was recently discovered by the Void Galaxy Survey inside a large void in the Sloan Digital Sky Survey galaxy redshift survey. H  i data revealed these galaxies to be embedded in a common elongated envelope, possibly embedded in intravoid filament. In the CosmoGrid simulation we look for systems similar to VGS_31 in mass, size and environment. We find a total of eight such systems. For these systems, we study the distribution of neighbour haloes, the assembly and evolution of the main haloes and the dynamical evolution of the haloes, as well as the evolution of the large-scale structure in which the systems are embedded. The spatial distribution of the haloes follows that of the dark matter environment. We find that VGS_31-like systems have a large variation in formation time, having formed between 10 Gyr ago and the present epoch. However, the environments in which the systems are embedded evolved to resemble each other substantially. Each of the VGS_31-like systems is embedded in an intravoid wall, that no later than z  = 0.5 became the only prominent feature in its environment. While part of the void walls retain a rather featureless character, we find that around half of them are marked by a pronounced and rapidly evolving substructure. Five haloes find themselves in a tenuous filament of a few h –1 Mpc long inside the intravoid wall. Finally, we compare the results to observed data from VGS_31. Our study implies that the VGS_31 galaxies formed in the same (proto)filament, and did not meet just recently. The diversity amongst the simulated halo systems indicates that VGS_31 may not be typical for groups of galaxies in voids.

Description: Using 3D numerical hydrodynamical simulations, we show that jets launched prior to Type Ia supernova (SN Ia) explosion in the core-degenerate (CD) scenario can account for the appearance of two opposite lobes (‘Ears’) along the symmetry axis of the SN remnant (SNR). In the double-degenerate (DD) and CD scenarios the merger of the two degenerate compact objects is very likely to lead to the formation of an accretion disc, that might launch two opposite jets. In the CD scenario, these jets interact with the envelope ejected during the preceding common envelope phase. If explosion occurs shortly after the merger process, the exploding gas and the jets will collide with the ejected nebula, leading to SNR with axisymmetric components including ‘Ears’. We also explore the possibility that the jets are launched by the companion white dwarf prior to its merger with the core. This last process is similar to the one where jets are launched in some pre-planetary nebulae. The SNR ‘Ears’ in this case are formed by a spherical SN Ia explosion inside an elliptical planetary nebula-like object. We compare our numerical results with two SNRs – Kepler and G299.2–2.9.

Description: Low-mass star-forming regions are more complex than the simple spherically symmetric approximation that is often assumed. We apply a more realistic infall/outflow physical model to molecular/continuum observations of three late Class 0 protostellar sources with the aims of (a) proving the applicability of a single physical model for all three sources and (b) deriving physical parameters for the molecular gas component in each of the sources. We have observed several molecular species in multiple rotational transitions. The observed line profiles were modelled in the context of a dynamical model which incorporates infall and bipolar outflows, using a three-dimensional radiative transfer code. This results in constraints on the physical parameters and chemical abundances in each source. Self-consistent fits to each source are obtained. We constrain the characteristics of the molecular gas in the envelopes as well as in the molecular outflows. We find that the molecular gas abundances in the infalling envelope are reduced, presumably due to freeze-out, whilst the abundances in the molecular outflows are enhanced, presumably due to dynamical activity. Despite the fact that the line profiles show significant source-to-source variation, which primarily derives from variations in the outflow viewing angle, the physical parameters of the gas are found to be similar in each core.

Description: We present predictions for hydrogen and helium emission line luminosities from circumstellar matter around Type Ia supernovae (SNe Ia) using time dependent photoionization modelling. Early high-resolution ESO/Very Large Telescope (VLT) optical echelle spectra of the SN Ia 2000cx were taken before and up to ~70 d after maximum to probe the existence of such narrow emission lines from the supernova. We detect no such lines, and from our modelling place an upper limit on the mass-loss rate for the putative wind from the progenitor system, $\skew4\dot{M}\lesssim 1.3\times 10^{-5} \,{\rm M}_{\odot }\,{\rm yr}^{-1}$ , assuming a speed of 10 km s –1 and solar abundances for the wind. If the wind would be helium-enriched and/or faster, the upper limit on $\skew4\dot{M}$ could be significantly higher. In the helium-enriched case, we show that the best line to constrain the mass-loss would be He i 10 830. In addition to confirming the details of interstellar Na i and Ca ii absorption towards SN 2000cx as discussed by Patat et al., we also find evidence for 6613.56 Å diffuse interstellar band absorption in the Milky Way. We also discuss measurements of the X-ray emission from the interaction between the supernova ejecta and the wind and we re-evaluate observations of SN 1992A obtained ~16 d after maximum by Schlegel & Petre. We find an upper limit of $\skew4\dot{M}\sim 1.3\times 10^{-5} \,{\rm M}_{\odot }\,{\rm yr}^{-1}$ which is significantly higher than that estimated by Schlegel & Petre. These results, together with the previous observational work on the normal SNe Ia 1994D and 2001el, disfavour a symbiotic star in the upper mass-loss rate regime (so-called Mira-type systems) from being the likely progenitor scenario for these SNe. Our model calculations are general, and can also be used for the subclass of SNe Ia that do show circumstellar interaction, e.g. the recent PTF 11kx. To constrain hydrogen in late-time spectra, we present ESO/VLT and ESO/New Technology Telescope optical and infrared observations of SNe Ia 1998bu and 2000cx in the nebular phase, 251-388 d after maximum. We see no signs of hydrogen line emission in SNe 1998bu and 2000cx at these epochs, and from the absence of Hα with a width of the order of ~10 3 km s –1 , we argue from modelling that the mass of such hydrogen-rich gas must be 0.03 M for both supernovae. Comparing similar upper limits with recent models of Pan et al., it seems that hydrogen-rich donors with a separation of 5 times the radius of the donor may be ruled out for the five SNe Ia 1998bu, 2000cx, 2001el, 2005am and 2005cf. Larger separation, helium-rich donors, or a double-degenerate origin for these supernovae seems more likely. Our models have also been used to put the limit on hydrogen-rich gas in the recent SN 2011fe, and for this supernova, a double-degenerate origin seems likely.

Description: We build differential-reddening maps for 66 Galactic globular clusters (GCs) with archival Hubble Space Telescope WFC/ACS F 606 W and F 814 W photometry. Because of the different GC sizes (characterized by the half-light radius R h ) and distances to the Sun, the WFC/ACS field of view (200 arcsec x 200 arcsec) coverage ( R obs ) lies in the range 1 R obs / R h 15 for about 85 per cent of the sample, with about 10 per cent covering only the inner ( R obs R h ) parts. We divide the WFC/ACS field of view across each cluster in a regular cell grid and extract the stellar-density Hess diagram from each cell, shifting it in colour and magnitude along the reddening vector until matching the mean diagram. Thus, the maps correspond to the internal dispersion of the reddening around the mean. Depending on the number of available stars (i.e. probable members with adequate photometric errors), the angular resolution of the maps range from 7 arcsec x 7 arcsec to 20 arcsec x 20 arcsec. We detect spatially variable extinction in the 66 GCs studied, with mean values ranging from 〈E(B-V)〉0.018 (NGC 6981) up to 〈E(B-V)〉0.016 (Palomar 2). Differential-reddening correction decreases the observed foreground reddening and the apparent distance modulus but, since they are related to the same value of E ( B  –  V ), the distance to the Sun is conserved. Fits to the mean-ridge lines of the highly extincted and photometrically scattered GC Palomar 2 show that age and metallicity also remain unchanged after the differential-reddening correction, but measurement uncertainties decrease because of the reduced scatter. The lack of systematic variations of 〈E(B-V)〉 with both the foreground reddening and the sampled cluster area indicates that the main source of differential reddening is interstellar.

Description: We present a physically motivated semi-analytic model to understand the clustering of high-redshift Lyman α emitters (LAEs). We show that the model parameters constrained by the observed luminosity functions can be used to predict large-scale bias and angular correlation function of LAEs. These predictions are shown to reproduce the observations remarkably well. We find that average masses of dark matter haloes hosting LAEs brighter than the threshold narrow-band magnitude ~25 are ~10 11 M . These are smaller than that of typical Lyman break galaxies (LBGs) brighter than a similar threshold continuum magnitude by a factor of ~10. This results in a smaller clustering strength of LAEs compared to LBGs. However, using the observed relationship between the UV continuum and Lyman α luminosity of LAEs, we show that both LAEs and LBGs belong to the same parent galaxy population with narrow-band techniques having greater efficiency in picking up galaxies with low UV luminosity. We also show that the lack of evidence for the presence of the one-halo term in the observed LAE angular correlation functions can be attributed to a sub-Poisson distribution of LAEs in dark matter haloes as a result of their low halo occupations.

Description: We present a detailed analysis of spectral line profiles in Type Ia supernova (SN Ia) spectra. We focus on the feature at ~3500–4000 Å, which is commonly thought to be caused by blueshifted absorption of Ca H&K. Unlike some other spectral features in SN Ia spectra, this feature often has two overlapping (blue and red) components. It is accepted that the red component comes from photospheric calcium. However, it has been proposed that the blue component is caused by either high-velocity calcium (from either abundance or density enhancements above the photosphere of the supernova, SN) or Si ii 3858. By looking at multiple data sets and model spectra, focusing on spectra near maximum brightness, we conclude that the blue component of the Ca H&K feature is caused by Si ii 3858 for most SNe Ia, although high-velocity calcium is likely important for some SNe. The strength of the Si ii 3858 feature varies strongly with the light-curve shape of an SN. As a result, the velocity measured from a single-Gaussian fit to the full line profile correlates with light-curve shape. The velocity of the Ca H&K component of the profile does not correlate with light-curve shape, contrary to previous claims. We detail the pitfalls of assuming that the blue component of the Ca H&K feature is caused by calcium, with implications for our understanding of SN Ia progenitors, explosions and cosmology.

Description: Subject of this paper is the statistical properties of ellipticity alignments between galaxies evoked by their coupled angular momenta. Starting from physical angular momentum models, we bridge the gap towards ellipticity correlations, ellipticity spectra and derived quantities such as aperture moments, comparing the intrinsic signals with those generated by gravitational lensing, with the projected galaxy sample of Euclid in mind. We investigate the dependence of intrinsic ellipticity correlations on cosmological parameters and show that intrinsic ellipticity correlations give rise to non-Gaussian likelihoods as a result of non-linear functional dependences. Comparing intrinsic ellipticity spectra to weak lensing spectra we quantify the magnitude of their contaminating effect on the estimation of cosmological parameters and find that biases on dark energy parameters are very small in an angular momentum-based model in contrast to the linear alignment model commonly used. Finally, we quantify whether intrinsic ellipticities can be measured in the presence of the much stronger weak lensing induced ellipticity correlations, if prior knowledge on a cosmological model is assumed.

Description: In this paper, I present a new method that has been developed for determining the brightness of a cloudless night sky, on the basis of widely available amateur observations of comets. The tests show the correctness of the method, which makes it possible to determine the level of light pollution, defined as the brightness of the artificial sky glow, through the use of the archival observations of comets. The use of data bases of comet observations in Poland in the period 1994–2009 has led to a positive verification of the known model map of the brightness of the night sky. Also, it has been possible to find changes in the level of light pollution in this period, at the selected observation sites.

Description: We present a complete sample of molecular clumps containing compact and ultracompact H ii (UC H ii ) regions between  = 10° and 60° and | b | 〈 1°, identified by combining the APEX Telescope Large Area Survey of the Galaxy submm and CORNISH radio continuum surveys with visual examination of archival infrared data. Our sample is complete to optically thin, compact and UC H ii regions driven by a zero-age main-sequence star of spectral type B0 or earlier embedded within a 1000 M clump. In total we identify 213 compact and UC H ii regions, associated with 170 clumps. Unambiguous kinematic distances are derived for these clumps and used to estimate their masses and physical sizes, as well as the Lyman continuum fluxes and sizes of their embedded H ii regions. We find a clear lower envelope for the surface density of molecular clumps hosting massive star formation of 0.05 g cm –2 , which is consistent with a similar sample of clumps associated with 6.7 GHz masers. The mass of the most massive embedded stars is closely correlated with the mass of their natal clump. Young B stars appear to be significantly more luminous in the ultraviolet than predicted by current stellar atmosphere models. The properties of clumps associated with compact and UC H ii regions are very similar to those associated with 6.7 GHz methanol masers and we speculate that there is little evolution in the structure of the molecular clumps between these two phases. Finally, we identify a significant peak in the surface density of compact and UC H ii -regions associated with the W49A star-forming complex, noting that this complex is truly one of the most massive and intense regions of star formation in the Galaxy.

Description: We present full Stokes radio polarization observations of the quasar PKS B2126–158 ( z  = 3.268) from 1 to 10 GHz using the Australia Telescope Compact Array. The source has large fractional circular polarization (CP), m c | V |/ I , detected at high significance across the entire band (from 15 to 90 per 128 MHz subband). This allows us to construct the most robust CP spectrum of an active galactic nucleus (AGN) jet to date. We find m c    +0.60 ± 0.03 from 1.5 to 6.5 GHz, with a peak of m c ~ 1 per cent before the spectrum turns over somewhere between 6.5 and 8 GHz, above which m c    –3.0 ± 0.4 . The fractional linear polarization (LP; p ) varies from 0.2 to ~1 per cent across our frequency range and is strongly anticorrelated with the fractional CP, with a best-fitting power law giving m c    p –0.24 ± 0.03 . This is the first clear relation between the observed LP and CP of an AGN jet, revealing the action of Faraday conversion of LP to CP within the jet. More detailed modelling in conjunction with high spatial resolution observations are required to determine the true driving force behind the conversion (i.e. magnetic twist or internal Faraday rotation). In particular determining whether the observed Faraday rotation is internal or entirely external to the jet is key to this goal. The simplest interpretation of our observations favours some internal Faraday rotation, implying that Faraday rotation-driven conversion of LP to CP is the dominant CP generation mechanism. In this case, a small amount of vector-ordered magnetic field along the jet axis is required, along with internal Faraday rotation from the low-energy end of the relativistic electron energy spectrum in an electron–proton-dominated jet.