ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Ihre E-Mail wurde erfolgreich gesendet. Bitte prüfen Sie Ihren Maileingang.

Leider ist ein Fehler beim E-Mail-Versand aufgetreten. Bitte versuchen Sie es erneut.

Vorgang fortführen?

Exportieren
Filter
  • 2015-2019  (37)
  • 1990-1994  (26)
Sammlung
Schlagwörter
Verlag/Herausgeber
Erscheinungszeitraum
Jahr
  • 1
    facet.materialart.
    Unbekannt
    A high reliability survey of discrete Epoch of Reionization foreground sources in the MWA EoR0 field (2016)
    Carroll, P. A., Line, J., Morales, M. F., Barry, N., Beardsley, A. P., Hazelton, B. J., Jacobs, D. C., Pober, J. C., Sullivan, I. S., Webster, R. L., Bernardi, G., Bowman, J. D., Briggs, F., Cappallo, R. J., Corey, B. E., de Oliveira-Costa, A., Dillon, J. S., Emrich, D., Ewall-Wice, A., Feng, L., Gaensler, B. M., Goeke, R., Greenhill, L. J., Hewitt, J. N., Hurley-Walker, N., Johnston-Hollitt, M., Kaplan, D. L., Kasper, J. C., Kim, H., Kratzenberg, E., Lenc, E., Loeb, A., Lonsdale, C. J., Lynch, M. J., McKinley, B., McWhirter, S. R., Mitchell, D. A., Morgan, E., Neben, A. R., Oberoi, D., Offringa, A. R., Ord, S. M., Paul, S., Pindor, B., Prabu, T., Procopio, P., Riding, J., Rogers, A. E. E., Roshi, A., Shankar, N. U., Sethi, S. K., Srivani, K. S., Subrahmanyan, R., Tegmark, M., Thyagarajan, N., Tingay, S. J., Trott, C. M., Waterson, M., Wayth, R. B., Whitney, A. R., Williams, A., Williams, C. L., Wu, C., Wyithe, J. S. B.
    Oxford University Press
    Details
    Publikationsdatum: 2016-07-29
    Beschreibung: Detection of the epoch of reionization H i signal requires a precise understanding of the intervening galaxies and AGN, both for instrumental calibration and foreground removal. We present a catalogue of 7394 extragalactic sources at 182 MHz detected in the RA = 0 field of the Murchison Widefield Array Epoch of Reionization observation programme. Motivated by unprecedented requirements for precision and reliability we develop new methods for source finding and selection. We apply machine learning methods to self-consistently classify the relative reliability of 9490 source candidates. A subset of 7466 are selected based on reliability class and signal-to-noise ratio criteria. These are statistically cross-matched to four other radio surveys using both position and flux density information. We find 7369 sources to have confident matches, including 90 partially resolved sources that split into a total of 192 sub-components. An additional 25 unmatched sources are included as new radio detections. The catalogue sources have a median spectral index of –0.85. Spectral flattening is seen towards lower frequencies with a median of –0.71 predicted at 182 MHz. The astrometric error is 7 arcsec compared to a 2.3 arcmin beam FWHM. The resulting catalogue covers ~1400 deg 2 and is complete to approximately 80 mJy within half beam power. This provides the most reliable discrete source sky model available to date in the MWA EoR0 field for precision foreground subtraction.
    Print ISSN: 0035-8711
    Digitale ISSN: 1365-2966
    Thema: Physik
    Publiziert von Oxford University Press
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    AKTUELLE ARTIKEL
  • 2
    facet.materialart.
    Unbekannt
    Local Ancestry Inference in a Large US-Based Hispanic/Latino Study: Hispanic Community Health Study/Study of Latinos (HCHS/SOL) (2016)
    Genetics Society of America (GSA)
    Details
    Publikationsdatum: 2016-06-02
    Beschreibung: We estimated local ancestry on the autosomes and X chromosome in a large US-based study of 12,793 Hispanic/Latino individuals using the RFMix method, and we compared different reference panels and approaches to local ancestry estimation on the X chromosome by means of Mendelian inconsistency rates as a proxy for accuracy. We developed a novel and straightforward approach to performing ancestry-specific PCA after finding artifactual behavior in the results from an existing approach. Using the ancestry-specific PCA, we found significant population structure within African, European, and Amerindian ancestries in the Hispanic/Latino individuals in our study. In the African ancestral component of the admixed individuals, individuals whose grandparents were from Central America clustered separately from individuals whose grandparents were from the Caribbean, and also from reference Yoruba and Mandenka West African individuals. In the European component, individuals whose grandparents were from Puerto Rico diverged partially from other background groups. In the Amerindian ancestral component, individuals clustered into multiple different groups depending on the grandparental country of origin. Therefore, local ancestry estimation provides further insight into the complex genetic structure of US Hispanic/Latino populations, which must be properly accounted for in genotype-phenotype association studies. It also provides a basis for admixture mapping and ancestry-specific allele frequency estimation, which are useful in the identification of risk factors for disease.
    Digitale ISSN: 2160-1836
    Thema: Biologie
    Publiziert von Genetics Society of America (GSA)
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    AKTUELLE ARTIKEL
  • 3
    facet.materialart.
    Unbekannt
    The 154 MHz radio sky observed by the Murchison Widefield Array: noise, confusion, and first source count analyses (2016)
    Oxford University Press
    Details
    Publikationsdatum: 2016-05-12
    Beschreibung: We analyse a 154 MHz image made from a 12 h observation with the Murchison Widefield Array (MWA) to determine the noise contribution and behaviour of the source counts down to 30 mJy. The MWA image has a bandwidth of 30.72 MHz, a field-of-view within the half-power contour of the primary beam of 570 deg 2 , a resolution of 2.3 arcmin and contains 13 458 sources above 5. The rms noise in the centre of the image is 4–5 mJy beam –1 . The MWA counts are in excellent agreement with counts from other instruments and are the most precise ever derived in the flux density range 30–200 mJy due to the sky area covered. Using the deepest available source count data, we find that the MWA image is affected by sidelobe confusion noise at the 3.5 mJy beam –1 level, due to incompletely peeled and out-of-image sources, and classical confusion becomes apparent at 1.7 mJy beam –1 . This work highlights that (i) further improvements in ionospheric calibration and deconvolution imaging techniques would be required to probe to the classical confusion limit and (ii) the shape of low-frequency source counts, including any flattening towards lower flux densities, must be determined from deeper 150 MHz surveys as it cannot be directly inferred from higher frequency data.
    Print ISSN: 0035-8711
    Digitale ISSN: 1365-2966
    Thema: Physik
    Publiziert von Oxford University Press
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    AKTUELLE ARTIKEL
  • 4
    facet.materialart.
    Unbekannt
    Detecting outliers in species distribution data: Some caveats and clarifications on a virtual species study (2019)
    Wiley
    Details
    Publikationsdatum: 2019
    Beschreibung: Abstract Liu et al. (2018) used a virtual species approach to test the effects of outliers on species distribution models. In their simulations, they applied a threshold value over the simulated suitabilities to generate the species distributions, suggesting that using a probabilistic simulation approach would have been more complex and yield the same results. Here, we argue that using a probabilistic approach is not necessarily more complex and may significantly change results. Although the threshold approach may be justified under limited circumstances, the probabilistic approach has multiple advantages. First, it is in line with ecological theory, which largely assumes non‐threshold responses. Second, it is more general, as it includes the threshold as a limiting case. Third, it allows a better separation of the relevant intervening factors that influence model performance. Therefore, we argue that the probabilistic simulation approach should be used as a general standard in virtual species studies.
    Print ISSN: 0305-0270
    Digitale ISSN: 1365-2699
    Thema: Biologie , Geographie
    Publiziert von Wiley
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    AKTUELLE ARTIKEL
  • 5
    facet.materialart.
    Unbekannt
    Conformational control of DNA target cleavage by CRISPR-Cas9 (2015)
    Nature Publishing Group (NPG)
    Details
    Publikationsdatum: 2015-11-03
    Beschreibung: Cas9 is an RNA-guided DNA endonuclease that targets foreign DNA for destruction as part of a bacterial adaptive immune system mediated by clustered regularly interspaced short palindromic repeats (CRISPR). Together with single-guide RNAs, Cas9 also functions as a powerful genome engineering tool in plants and animals, and efforts are underway to increase the efficiency and specificity of DNA targeting for potential therapeutic applications. Studies of off-target effects have shown that DNA binding is far more promiscuous than DNA cleavage, yet the molecular cues that govern strand scission have not been elucidated. Here we show that the conformational state of the HNH nuclease domain directly controls DNA cleavage activity. Using intramolecular Forster resonance energy transfer experiments to detect relative orientations of the Cas9 catalytic domains when associated with on- and off-target DNA, we find that DNA cleavage efficiencies scale with the extent to which the HNH domain samples an activated conformation. We furthermore uncover a surprising mode of allosteric communication that ensures concerted firing of both Cas9 nuclease domains. Our results highlight a proofreading mechanism beyond initial protospacer adjacent motif (PAM) recognition and RNA-DNA base-pairing that serves as a final specificity checkpoint before DNA double-strand break formation.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Sternberg, Samuel H -- LaFrance, Benjamin -- Kaplan, Matias -- Doudna, Jennifer A -- T32GM007232/GM/NIGMS NIH HHS/ -- Howard Hughes Medical Institute/ -- England -- Nature. 2015 Nov 5;527(7576):110-3. doi: 10.1038/nature15544. Epub 2015 Oct 28.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry, University of California, Berkeley, California 94720, USA. ; Department of Molecular and Cell Biology, University of California, Berkeley, California 94720, USA. ; Howard Hughes Medical Institute, University of California, Berkeley, California 94720, USA. ; Innovative Genomics Initiative, University of California, Berkeley, California 94720, USA. ; Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/26524520" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Allosteric Regulation ; Bacterial Proteins/chemistry/metabolism ; Base Pairing ; Binding Sites ; CRISPR-Associated Proteins/*chemistry/*metabolism ; *CRISPR-Cas Systems ; Catalytic Domain ; DNA/chemistry/*metabolism ; DNA Breaks, Double-Stranded ; *DNA Cleavage ; Endonucleases/chemistry/*metabolism ; Fluorescence Resonance Energy Transfer ; *Genetic Engineering ; Models, Molecular ; RNA, Guide/chemistry/metabolism ; Streptococcus pyogenes
    Print ISSN: 0028-0836
    Digitale ISSN: 1476-4687
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Publiziert von Nature Publishing Group (NPG)
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    AKTUELLE ARTIKEL
  • 6
    facet.materialart.
    Unbekannt
    A radio counterpart to a neutron star merger (2017)
    American Association for the Advancement of Science (AAAS)
    In: Science
    Details
    Publikationsdatum: 2017-12-22
    Beschreibung: Gravitational waves have been detected from a binary neutron star merger event, GW170817. The detection of electromagnetic radiation from the same source has shown that the merger occurred in the outskirts of the galaxy NGC 4993, at a distance of 40 megaparsecs from Earth. We report the detection of a counterpart radio source that appears 16 days after the event, allowing us to diagnose the energetics and environment of the merger. The observed radio emission can be explained by either a collimated ultrarelativistic jet, viewed off-axis, or a cocoon of mildly relativistic ejecta. Within 100 days of the merger, the radio light curves will enable observers to distinguish between these models, and the angular velocity and geometry of the debris will be directly measurable by very long baseline interferometry.
    Schlagwort(e): Astronomy
    Print ISSN: 0036-8075
    Digitale ISSN: 1095-9203
    Thema: Biologie , Chemie und Pharmazie , Geologie und Paläontologie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
    Publiziert von American Association for the Advancement of Science (AAAS)
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    AKTUELLE ARTIKEL
  • 7
    Digitale Medien
    Digitale Medien
    Reactivity of C60 in pure oxygen (1991)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 59 (1991), S. 2956-2958 
    Details
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: In pure oxygen at moderate temperatures of 200 °C, an fcc C60 transforms into amorphous carbon-oxygen compounds and the icosahedral C60 molecular structure is destroyed. The maximum oxygen uptake of pure C60, O/C60, is 12. Isothermal TGA transformation curves are sigmoid-shaped with the kinetic exponent n∼5/2 which conforms with a two-dimensional nucleation and growth mode. The heat of formation for the carbon-oxygen compounds is 90 kcal/mol O, and the formation energy for the reaction: 60C (graphite)→C60 molecule is estimated to be ∼600 kcal/mol.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.105810
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 8
    Digitale Medien
    Digitale Medien
    History, Structure, and Ritual (1990)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Anthropology 19 (1990), S. 119-150 
    Details
    ISSN: 0084-6570
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Ethnologie , Biologie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.an.19.100190.001003
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 9
    Digitale Medien
    Digitale Medien
    Meso-beta scale numerical simulations of terrain drag-induced along-stream circulations. Part II: Concentration of potential vorticity within dryline bulges (1992)
    Springer
    Meteorology and atmospheric physics 49 (1992), S. 157-185 
    Details
    ISSN: 1436-5065
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geographie , Physik
    Notizen: Summary Hydrostatic and nonhydrostatic simulation models are employed to study the intensification of a terrain drag-induced dryline. The study develops a multi-stage theory for the evolution of the dryline including the concentration of potential vorticity accompanying meso-gamma scale dryline “bulges”. The numerical simulations indicate three fundamental stages of dryline intensification all of which are either directly or indirectly a result of the terrain-drag on the mid/upper-tropospheric jet stream by the Front Range of the Colorado Rocky Mountains. The first stage involves the downward momentum flux accompanying a large amplitude hydrostatic mountain wave which induces a downslope windstorm along the lee slopes. The surge of momentum (i.e., the dry, warm air associated with the downslope windstorm) propagates down the leeslope and modifies an existing weak dryline boundary. As the downslope windstorm initiates an undular bore along the lee slopes, the high momentum gradient which propagates downstream accompanying the bore, as well as the strong lower tropospheric sinking motions ahead of the bore, contract the scale of the surface moisture boundary between the dry air from above the leeslope and the moist air over the High Plains. This process further strengthens the dryline. The second stage involves the coupling of the terrain drag-induced along-stream ageostrophic front within the midtroposphere to the boundary layer through a thermally-indirect circulation. As the along-stream ageostrophic circulation intensifies within the middle troposphere down-stream from the mountain wave, sinking air parcels originating above 40 kPa descend to below 60 kPa over the High Plains where surface pressures are, only ∼85 kPa. These descending air parcels within the upstream branch of the along-stream ageostrophic thermally-indirect circulation contain high values of momentum and very low dewpoint values. As the planetary boundary layer (PBL) deepens due to surface warming during the morning hours, momentum and dry air from the midtropospheric along-stream ageostrophic front are entrained into the PBL. This process amplifies the bore-induced hydrostatic dryline bulge via low-level ageostrophic confluence. Finally, regions of low Richardson number (arising from strong vertical shears) within the amplifying midtropospheric along-stream ageostrophic thermally-indirect circulation become preferred regions for the development of non-hydrostatic evanescent internal gravity waves. These waves are embedded within the hydrostatic along-stream front above the low-level dryline and are accomapanied by very significant values of vertical momentum flux which act to focus the meso-gamma scale structure of the dryline into smaller scale bulges where low-level winds and vorticities are very high. This meso-gamma scale process follows the hydrostatic tilting and vortex tube stretching which creates meso-beta scale maxima of mid-lower tropospheric vorticity. The turbulent momentum fluxes accompanying wavebreaking within the nonhydrostatic dryline bulge create very large (i.e., stratospheric values of) potential vorticity near 70 kPa due to the nonconservation of potential vorticity on isentropic surfaces.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01025406
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 10
    Digitale Medien
    Digitale Medien
    Meso-beta scale numerical simulations of terrain drag-induced along-stream circulations Part I: Midtropospheric frontogenesis (1992)
    Springer
    Meteorology and atmospheric physics 49 (1992), S. 133-156 
    Details
    ISSN: 1436-5065
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geographie , Physik
    Notizen: Summary The problem of along-stream ageostrophic frontogenesis is studied by employing a numerical model at meso-alpha and meso-beta scales in simulations of the downstream circulations over the Front Range of the Rocky Mountains. Three-dimensional real data simulations at these two scales of motion are used to diagnose the transition from semigeostrophic cross-stream frontogenesis accompanying a propagating baroclinic upper-level jet streak to midtropospheric along-stream ageostrophic frontogenesis. This along-stream ageostrophic frontogenesis results from the perturbation of the jet streak by the Rocky Mountain range. The case study represents an example of internal wave dynamics which are forced by the drag of the Rocky Mountains on a strong jet streak in the presence of a low-level inversion. The simulation results indicate that, unlike semi-geostrophic frontogenesis, a front (which is alligned perpendicular to the axis of the jet stream) may form when significant adiabatic heating occurs within a stratified shear flow over horizontal length scales shorter than the Rossby radius of deformation. The mechanism responsible for the frontogenesis is the growth of the divergent along-stream wind velocity component which becomes coupled to the front's along-stream pressure gradient force. This nonlinear interaction produces hydrostatic mesoscale frontogenesis as follows: 1) vertical wind shear in the along-stream plane strengthens resulting in the increasingly nonuniform vertical variation of horizontal temperature advection as the ageostrophic wind component grows in magnitude downstream of the meso-scale terrain-induced adiabatic heating, 2) increasing along-stream differential vertical motions (i.e., along-stream thermally indirect circulation with warm air sinking to the west and cold air rising to the east) tilt the vertical gradient of isentropes into the horizontal as the vertical temperature gradient increases due to the previous process in proximity to horizontal gradients in the along-stream component of the ageostrophic wind, 3) as tilting motions act to increase the along-stream horizontal temperature gradient, the along-stream confluence acts to nonuniformly increase the along-stream frontal temperature gradient which increases the along-stream pressure gradient force resulting in further accelerations, ageostrophy, and frontal steepening as part of a scale contraction process. The evolution of the aforementioned processes results in the three-dimensional hydrostatic frontogenesis accompanying the overturning of isentropic surfaces. These adjustments act to turn air parcels to the right of the southwesterly geostrophic wind vector at successively lower atmospheric levels as the scale contraction continues. This simulated along-stream front is verified from diagnostic analysis of the profiler-derived temperature and wind fields.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01025405
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
Schließen ⊗
Diese Webseite nutzt Cookies und das Analyse-Tool Matomo. Weitere Informationen finden Sie hier...