4,245 research outputs found
The acidic domain of the endothelial membrane protein GPIHBP1 stabilizes lipoprotein lipase activity by preventing unfolding of its catalytic domain.
GPIHBP1 is a glycolipid-anchored membrane protein of capillary endothelial cells that binds lipoprotein lipase (LPL) within the interstitial space and shuttles it to the capillary lumen. The LPLâąGPIHBP1 complex is responsible for margination of triglyceride-rich lipoproteins along capillaries and their lipolytic processing. The current work conceptualizes a model for the GPIHBP1âąLPL interaction based on biophysical measurements with hydrogen-deuterium exchange/mass spectrometry, surface plasmon resonance, and zero-length cross-linking. According to this model, GPIHBP1 comprises two functionally distinct domains: (1) an intrinsically disordered acidic N-terminal domain; and (2) a folded C-terminal domain that tethers GPIHBP1 to the cell membrane by glycosylphosphatidylinositol. We demonstrate that these domains serve different roles in regulating the kinetics of LPL binding. Importantly, the acidic domain stabilizes LPL catalytic activity by mitigating the global unfolding of LPL's catalytic domain. This study provides a conceptual framework for understanding intravascular lipolysis and GPIHBP1 and LPL mutations causing familial chylomicronemia
Poisson limits for U-statistics
AbstractWe study Poisson limits for U-statistics with non-negative kernels. The limit theory is derived from the Poisson convergence of suitable point processes of U-statistics structure. We apply these results to derive infinite variance stable limits for U-statistics with a regularly varying kernel and to determine the index of regular variation of the left tail of the kernel. The latter is known as correlation dimension. We use the point process convergence to study the asymptotic behavior of some standard estimators of this dimension
The Caenorhabditis eleguns genome contains monomorphic minisatellites and simple sequences
Many species have been shown to contain tandemly repeated short sequence DNA kinown as minisatellites and simple sequence motifs. Due to allelic variation in the copy number of the repeat unit these loci are usually highly polymorphic. Here we demonstrate the presence of sequences in the genome of the nematode Caenorhabditis elegans which are homologous to two sets of short sequence DNA. However, when two independent strains were compared no polymorphism for these sequences could be detected.</p
Warm Extended Dense Gas Lurking At The Heart Of A Cold Collapsing Dense Core
In order to investigate when and how the birth of a protostellar core occurs,
we made survey observations of four well-studied dense cores in the Taurus
molecular cloud using CO transitions in submillimeter bands. We report here the
detection of unexpectedly warm (~ 30 - 70 K), extended (radius of ~ 2400 AU),
dense (a few times 10^{5} cm^{-3}) gas at the heart of one of the dense cores,
L1521F (MC27), within the cold dynamically collapsing components. We argue that
the detected warm, extended, dense gas may originate from shock regions caused
by collisions between the dynamically collapsing components and
outflowing/rotating components within the dense core. We propose a new stage of
star formation, "warm-in-cold core stage (WICCS)", i.e., the cold collapsing
envelope encases the warm extended dense gas at the center due to the formation
of a protostellar core. WICCS would constitutes a missing link in evolution
between a cold quiescent starless core and a young protostar in class 0 stage
that has a large-scale bipolar outflow.Comment: Accepted for publication in The Astrophysical Journal Letter
Third order nonlinear susceptibility of InN at near band-gap wavelengths
The authors report room-temperature measurements of the third order nonlinear susceptibility modulus â« (3) â« of thick (âŒ600 nm) InN layers. Transmission measurements provide a room-temperature value for the optical band gap of the samples slightly above 1500 nm. Third order nonlinear optical susceptibility has been measured using degenerate four wave mixing experiments at wavelengths near and above band gap. â« (3) â« values of (4.2-10) Ă 10-10 esu were measured at this wavelength range. The associated relaxation time of the generated population grating at 1500 nm was measured. The obtained value of 4.8 ps is consistent with a nonradiative recombination mechanism. © 2007 American Institute of Physics.Peer Reviewe
The K+K+ Scattering Length from Lattice QCD
The K+K+ scattering length is calculated in fully-dynamical lattice QCD with
domain-wall valence quarks on the MILC asqtad-improved gauge configurations
with rooted staggered sea quarks. Three-flavor mixed-action chiral perturbation
theory at next-to-leading order, which includes the leading effects of the
finite lattice spacing, is used to extrapolate the results of the lattice
calculation to the physical value of m_{K+}/f_{K+}. We find m_{K+} a_{K+K+} =
-0.352 +- 0.016, where the statistical and systematic errors have been combined
in quadrature.Comment: 17 pages, 12 figures. NPLQCD collaboratio
Precise Determination of the I=2 pipi Scattering Length from Mixed-Action Lattice QCD
The I=2 pipi scattering length is calculated in fully-dynamical lattice QCD
with domain-wall valence quarks on the asqtad-improved coarse MILC
configurations (with fourth-rooted staggered sea quarks) at four light-quark
masses. Two- and three-flavor mixed-action chiral perturbation theory at
next-to-leading order is used to perform the chiral and continuum
extrapolations. At the physical charged pion mass, we find m_pi a_pipi(I=2) =
-0.04330 +- 0.00042, where the error bar combines the statistical and
systematic uncertainties in quadrature.Comment: 20 pages, 7 figure
G_2 Domain Walls in M-theory
M-theory is considered in its low-energy limit on a G_2 manifold with
non-vanishing flux. Using the Killing spinor equations for linear flux, an
explicit set of first-order bosonic equations for supersymmetric solutions is
found. These solutions describe a warped product of a domain wall in
four-dimensional space-time and a deformed G_2 manifold. It is shown how these
domain walls arise from the perspective of the associated four-dimensional N=1
effective supergravity theories. We also discuss the inclusion of membrane and
M5-brane sources.Comment: 30 pages, Late
An integrated 4249 marker FISH/RH map of the canine genome
BACKGROUND: The 156 breeds of dog recognized by the American Kennel Club offer a unique opportunity to map genes important in genetic variation. Each breed features a defining constellation of morphological and behavioral traits, often generated by deliberate crossing of closely related individuals, leading to a high rate of genetic disease in many breeds. Understanding the genetic basis of both phenotypic variation and disease susceptibility in the dog provides new ways in which to dissect the genetics of human health and biology. RESULTS: To facilitate both genetic mapping and cloning efforts, we have constructed an integrated canine genome map that is both dense and accurate. The resulting resource encompasses 4249 markers, and was constructed using the RHDF5000-2 whole genome radiation hybrid panel. The radiation hybrid (RH) map features a density of one marker every 900 Kb and contains 1760 bacterial artificial chromosome clones (BACs) localized to 1423 unique positions, 851 of which have also been mapped by fluorescence in situ hybridization (FISH). The two data sets show excellent concordance. Excluding the Y chromosome, the map features an RH/FISH mapped BAC every 3.5 Mb and an RH mapped BAC-end, on average, every 2 Mb. For 2233 markers, the orthologous human genes have been established, allowing the identification of 79 conserved segments (CS) between the dog and human genomes, dramatically extending the length of most previously described CS. CONCLUSIONS: These results provide a necessary resource for the canine genome mapping community to undertake positional cloning experiments and provide new insights into the comparative canine-human genome maps
Sprachliche Verfahren des Wissensmanagements im Kriminalroman : Ein Beitrag zur dynamischen Texttheorie
FĂŒr die Textlinguistik ist der Kriminalroman als Untersuchungsgegenstand ausgesprochen lehrreich, weil darin zwei textlinguistische Parameter besonders markant ausgeprĂ€gt sind, nĂ€mlich der Wissensaufbau und das darauf bezogene Referieren. Ziel der vorliegenden Arbeit ist es, die sprachlichen Verfahren des Wissensmanagements im Kriminalroman aus textlinguistischer Sicht einer pragmatischen und referenzsemantischen Untersuchung zu unterziehen. Dieser Zielsetzung entsprechend werden in der Arbeit unter anderem die folgenden Thesen aufgestellt und anhand ausgewĂ€hlter Textbeispiele plausibel gemacht: (1) Im Kriminalroman ist ein spezifisches Wissensmanagement nachweisbar, durch welches sich der Kriminalroman von anderen Texttypen unterscheidet, und (2) Die Art und Weise, wie Wissen in Texten typischerweise aufgebaut, strukturiert und vermittelt wird, kann als Spezifikum eines Texttyps gelten. Am Beispiel des Kriminalromans wird gezeigt, dass Formen des krimispezifischen Wissensmanagements und die dafĂŒr verwendeten charakteristischen sprachlichen Verfahren zu den konstituierenden Besonderheiten des Texttyps gehören. Als Grundlage fĂŒr die Untersuchung dient ein Textkorpus mit mehr als 100 deutschsprachigen Krimis, das sowohl Originalwerke als auch Ăbersetzungen umfasst. Bei der Untersuchung liegt der Fokus vor allem auf Verfahren des systematischen Wissensaufbaus und der Wissensentwicklung sowie dem Zusammenspiel von Wissensvermittlung und Formen des Referierens.
Theoretische Grundlage der Arbeit ist eine funktionale und dynamische Texttheorie. Der Ausgangspunkt bildet demnach die Grundidee, dass das Wissensmanagement ein zentraler Aspekt der Textorganisation ist, der eng mit anderen Aspekten zusammenhĂ€ngt und mit diesen auf vielfĂ€ltige Weise zusammenwirkt. Ausgehend von den Annahmen, dass die Grundfunktion des Kriminalromans darin besteht, durch die Erzeugung von Spannung den Leser zu unterhalten, und dass Spannungserzeugung im Wesentlichen durch den Wissensaufbau geleistet wird, werden grundlegende Mittel und Strategien des Wissensmanagements im Kriminalroman beschrieben. Zum theoretischen Rahmen der Arbeit gehören auch eine handlungstheoretische Referenztheorie, literaturwissenschaftliche Krimi-Forschung und ErzĂ€hltheorien sowie Schreibratgeber fĂŒr Krimis, in denen erfolgreiche Krimiautoren reflexiv Darstellungsstrategien und Erfolgsrezepte beschreiben. Bei der Untersuchung wird die Ergiebigkeit textlinguistischer Methoden und AnsĂ€tze im Zuge einer umfassenden sprachlichen Analyse des Wissensmanagements im Genre Kriminalroman erwiesen.
Diese Arbeit stellt insbesondere einen Beitrag zur dynamischen Texttheorie dar. Anhand einer Fallstudie von Andrea Maria Schenkels "Tannöd", bei der das Verfahren der WissensbuchfĂŒhrung in Form eines Leseprotokolls mit anschlieĂender Mikroanalyse zum Einsatz kommt, werden die Wissensdynamik in "Tannöd" und die jeweils verfĂŒgbaren WissensstĂ€nde und Wissensressourcen zu unterschiedlichen Text-Zeitpunkten modelliert. Dadurch wird der Grundgedanke einer dynamischen Texttheorie veranschaulicht, nĂ€mlich dass sich mit jedem neuen "Zug", jeder neuen Texthandlung, der "Spielstand" bzw. Wissensstand verĂ€ndert. Diese Fallstudie belegt, dass der Kriminalroman ein besonders markantes Beispiel fĂŒr den dynamischen Aspekt des Wissensaufbaus in Texten ist. Der Wissensaufbau ist ein Parameter der Textorganisation, der bisher in der Diskussion von Texttypologien noch nicht ausreichend Beachtung gefunden hat. Die Untersuchung von Krimis ist damit auch ein besonders lohnendes Untersuchungsfeld fĂŒr die Weiterentwicklung der textlinguistischen Theoriebildung
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