469 research outputs found
Soft grain compression: beyond the jamming point
We present the experimental studies of highly strained soft bidisperse
granular systems made of hyperelastic and plastic particles. We explore the
behavior of granular matter deep in the jammed state from local field
measurement from the grain scale to the global scale. By mean of digital image
correlation and accurate image recording we measure for each compression step
the evolution of the particle geometries and their right Cauchy-Green strain
tensor fields. We analyze the evolution of the usual macroscopic observables
(stress, packing fraction, coordination, fraction of non-rattlers,
\textit{etc}.) along the compression process through the jamming point and far
beyond. We also analyze the evolution of the local strain statistics and
evidence a crossover in the material behavior deep in the jammed state. We show
that this crossover depends on the particle material. We argue that the strain
field is a reliable observable to describe the evolution of a granular system
through the jamming transition and deep in the dense packing state whatever is
the material behavior.Comment: 10 figure
Optomechanical Transduction and Characterization of a Silica Microsphere Pendulum via Evanescent Light
Dissipative optomechanics has some advantages in cooling compared to the
conventional dispersion dominated systems. Here, we study the optical response
of a cantilever-like, silica, microsphere pendulum, evanescently coupled to a
fiber taper. In a whispering gallery mode resonator the cavity mode and motion
of the pendulum result in both dispersive and dissipative optomechanical
interactions. This unique mechanism leads to an experimentally observable,
asymmetric response function of the transduction spectrum which can be
explained using coupled-mode theory. The optomechanical transduction, and its
relationship to the external coupling gap, are investigated and we show that
the experimental behavior is in good agreement with the theoretical
predictions. A deep understanding of this mechanism is necessary to explore
trapping and cooling in dissipative optomechanical systems.Comment: 5 page
Using Term Position Similarity and Language Modeling for Bilingual Document Alignment
The WMT Bilingual Document Alignment
Task requires systems to assign
source pages to their âtranslationsâ, in a
big space of possible pairs. We present
four methods: The first one uses the term
position similarity between candidate document
pairs. The second method requires
automatically translated versions of the
target text, and matches them with the candidates.
The third and fourth methods try
to overcome some of the challenges presented
by the nature of the corpus, by
considering the string similarity of source
URL and candidate URL, and combining
the first two approaches
Moloney murine leukemia virus decay mediated by retroviral reverse transcriptase degradation of genomic RNA
AbstractRetroviral vectors are powerful tools for the introduction of transgenes into mammalian cells and for long-term gene expression. However, their application is often limited by a rapid loss of bioactivity: retroviruses spontaneously loose activity at 37 °C, with a half-life of 4 to 9 h depending on the retrovirus type. We sought to determine which components of the retrovirus are responsible for this loss in bioactivity and to obtain a quantitative characterization of their stability. To this end, we focused on RNA and viral proteins, two major components that we hypothesized may undergo degradation and negatively influence viral infectivity. Reverse transcription PCR (RT-PCR) targeting RNA encoding portions of the viral genome clearly demonstrated time-dependent degradation of RNA which correlated with the loss in viral bioactivity. Circular dichroism spectroscopy, SDS-PAGE and two-dimensional SDS-PAGE analyses of viral proteins did not show any change in secondary structure or evidence of proteolysis. The mechanism underlying the degradation of viral RNA was investigated by site-directed mutagenesis of proteins encoded by the viral genome. Reverse transcriptase and protease mutants exhibited enhanced RNA stability in comparison to wild type recombinant virus, suggesting that the degradation of RNA, and the corresponding virus loss of activity, is mediated by the reverse transcriptase enzyme
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Diagnostic test interpretation and referral delay in patients with interstitial lung disease.
BACKGROUND:Diagnostic delays are common in patients with interstitial lung disease (ILD). A substantial percentage of patients experience a diagnostic delay in the primary care setting, but the factors underpinning this observation remain unclear. In this multi-center investigation, we assessed ILD reporting on diagnostic test interpretation and its association with subsequent pulmonology referral by a primary care physician (PCP). METHODS:A retrospective cohort analysis of patients referred to the ILD programs at UC-Davis and University of Chicago by a PCP within each institution was performed. Computed tomography (CT) of the chest and abdomen and pulmonary function test (PFT) were reviewed to identify the date ILD features were first present and determine the time from diagnostic test to pulmonology referral. The association between ILD reporting on diagnostic test interpretation and pulmonology referral was assessed, as was the association between years of diagnostic delay and changes in fibrotic features on longitudinal chest CT. RESULTS:One hundred and forty-six patients were included in the final analysis. Prior to pulmonology referral, 66% (n =â97) of patients underwent chest CT, 15% (n =â21) underwent PFT and 15% (nâ=â21) underwent abdominal CT. ILD features were reported on 84, 62 and 33% of chest CT, PFT and abdominal CT interpretations, respectively. ILD reporting was associated with shorter time to pulmonology referral when undergoing chest CT (1.3 vs 15.1âmonths, respectively; p =â0.02), but not PFT or abdominal CT. ILD reporting was associated with increased likelihood of pulmonology referral within 6 months of diagnostic test when undergoing chest CT (rate ratio 2.17, 95% CI 1.03-4.56; p =â0.04), but not PFT or abdominal CT. Each year of diagnostic delay was associated with a 1.8% increase in percent fibrosis on chest CT. Patients with documented dyspnea had shorter time to chest CT acquisition and pulmonology referral than patients with documented cough and lung crackles. CONCLUSIONS:Determinants of ILD diagnostic delays in the primary care setting include underreporting of ILD features on diagnostic testing and prolonged time to pulmonology referral even when ILD is reported. Interventions to modulate these factors may reduce ILD diagnostic delays in the primary care setting
The Human Connectome Project 7 Tesla retinotopy dataset: Description and population receptive field analysis
The Human Connectome Project 7 Tesla retinotopy dataset: Description and population receptive field analysis
Limits of agricultural greenhouse gas calculators to predict soil N2O and CH4 fluxes in tropical agriculture
Acknowledgements This work was undertaken as part of the CGIAR Research Program on Climate Change, Agriculture and Food Security (CCAFS), which is a strategic partnership of CGIAR and Future Earth. This research was carried out with funding by the European Union (EU) and with technical support from the International Fund for Agricultural Development (IFAD). The UN FAO Mitigation of Climate Change in Agriculture (MICCA) Programme funded data collection in Kenya and Tanzania. The views expressed in the document cannot be taken to reflect the official opinions of CGIAR, Future Earth, or donors. We thank Louis Bockel of the UN FAO Agricultural Development Economics Division (ESA) for his comments on an earlier draft of the manuscript.Peer reviewedPublisher PD
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