1,039 research outputs found
Variations of Particle Size Distribution, Black Carbon, and Brown Carbon during a Severe Winter Pollution Event over Xi'an, China
Real-time particulate matter (PM) size distributions, 4-hour time resolution, PM2.5, carbonaceous materials, and their optical properties were measured during a severe pollution event in Xi'an, China High PM2.5 /PM10 ratios were observed on both pollution (0.83) and non-pollution (0.73) days, emphasizing the abundance of fine particles during sampling days. The particle number (PN) first peaked with a wide size range (30-100 nm) before morning rush hours (approximately 01:00-05:00) on pollution and non-pollution days, demonstrating that PN was governed by the accumulation of freshly emitted diesel particles and characterized by distinct aerosol condensation growth. By contrast, the second peak time and size range differed between pollution and non-pollution days because of different formation mechanisms The light-absorbing coefficients of both black carbon (BC, b(abs-880nm,BC)) and brown carbon (BrC, b(abs-370nm, BrC)) were high on pollution days and decreased to approximately half of those values on non-pollution days, indicating that the degree of light absorption is reduced by rain. The diurnal variation in b(abs-880nm, BC) pollution peaked with traffic on January 1 and 2. By contrast, it remained in relatively stable and high ranges (120-160 Mm(-1)) in the second period (January 3-5) without traffic peaks, illustrating that the dominant sources changed even during the same pollution period. High values of both b(abs-370nm, BrC) and b(abs-880nm,) (BC )coincided in the afternoon and evening due to emissions from primary sources, and abundant aqueous secondary organic carbon, respectively. A highly variable mass absorption coefficient of BrC also indicated the variety of fuel combustion sources of primary BrC in Xi'an
Real-time correlators in warped AdS/CFT correspondence
We study real-time correlators in the warped AdS/CFT correspondence. We apply
the prescription used in the usual AdS/CFT correspondence and obtain the
retarded Green's functions for the scalar and vector fields in the spacelike
warped and the null warped black hole backgrounds. We find that the retarded
Green's functions and the cross sections are well consistent with the
predictions from dual CFT. Our results not only support strongly the
conjectured warped AdS/CFT correspondence, but also show that the usual
relativistic AdS/CFT prescription of obtaining the real-time correlators remain
effective in more general backgrounds with anisotropic conformal infinity.Comment: 27 page
The dependence of dijet production on photon virtuality in ep collisions at HERA
The dependence of dijet production on the virtuality of the exchanged photon,
Q^2, has been studied by measuring dijet cross sections in the range 0 < Q^2 <
2000 GeV^2 with the ZEUS detector at HERA using an integrated luminosity of
38.6 pb^-1.
Dijet cross sections were measured for jets with transverse energy E_T^jet >
7.5 and 6.5 GeV and pseudorapidities in the photon-proton centre-of-mass frame
in the range -3 < eta^jet <0. The variable xg^obs, a measure of the photon
momentum entering the hard process, was used to enhance the sensitivity of the
measurement to the photon structure. The Q^2 dependence of the ratio of low- to
high-xg^obs events was measured.
Next-to-leading-order QCD predictions were found to generally underestimate
the low-xg^obs contribution relative to that at high xg^obs. Monte Carlo models
based on leading-logarithmic parton-showers, using a partonic structure for the
photon which falls smoothly with increasing Q^2, provide a qualitative
description of the data.Comment: 35 pages, 6 eps figures, submitted to Eur.Phys.J.
A combinatorial TIR1/AFB–Aux/IAA co-receptor system for differential sensing of auxin
The plant hormone auxin regulates virtually every aspect of plant growth and development. Auxin acts by binding the F-box protein transport inhibitor response 1 (TIR1) and promotes the degradation of the AUXIN/INDOLE-3-ACETIC ACID (Aux/IAA) transcriptional repressors. Here we show that efficient auxin binding requires assembly of an auxin co-receptor complex consisting of TIR1 and an Aux/IAA protein. Heterologous experiments in yeast and quantitative IAA binding assays using purified proteins showed that different combinations of TIR1 and Aux/IAA proteins form co-receptor complexes with a wide range of auxin-binding affinities. Auxin affinity seems to be largely determined by the Aux/IAA. As there are 6 TIR1/AUXIN SIGNALING F-BOX proteins (AFBs) and 29 Aux/IAA proteins in Arabidopsis thaliana, combinatorial interactions may result in many co-receptors with distinct auxin-sensing properties. We also demonstrate that the AFB5–Aux/IAA co-receptor selectively binds the auxinic herbicide picloram. This co-receptor system broadens the effective concentration range of the hormone and may contribute to the complexity of auxin response
Beauty photoproduction measured using decays into muons in dijet events in ep collisions at =318 GeV
The photoproduction of beauty quarks in events with two jets and a muon has
been measured with the ZEUS detector at HERA using an integrated luminosity of
110 pb. The fraction of jets containing b quarks was extracted from the
transverse momentum distribution of the muon relative to the closest jet.
Differential cross sections for beauty production as a function of the
transverse momentum and pseudorapidity of the muon, of the associated jet and
of , the fraction of the photon's momentum participating in
the hard process, are compared with MC models and QCD predictions made at
next-to-leading order. The latter give a good description of the data.Comment: 32 pages, 6 tables, 7 figures Table 6 and Figure 7 revised September
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Eliciting health state utilities for Dupuytren's contracture using a discrete choice experiment
Background and purpose An internet-based discrete choice
experiment (DCE) was conducted to elicit preferences for a wide
range of Dupuytren’s contracture (DC)-related health states. An
algorithm was subsequently developed to convert these preferences
into health state utilities that can be used to assess DC’s
impact on quality of life and the value of its treatments.
Methods Health state preferences for varying levels of DC
hand severity were elicited via an internet survey from a sample
of the UK adult population. Severity levels were deined using a
combination of contractures (0, 45, or 90 degrees) in 8 proximal
interphalangeal and metacarpophalangeal joints of the index,
middle, ring, and little ingers. Right-handed, left-handed, and
ambidextrous respondents indicated which hand was preferable
in each of the 10 randomly-selected hand-pairings comparing
different DC severity levels. For consistency across comparisons,
anatomically precise digital hand drawings were used. To anchor
preferences onto the traditional 0–1 utility scale used in health
economic evaluations, unaffected hands were assigned a utility
of 1.0 whereas the utility for a maximally affected hand (i.e., all
8 joints set at 90 degrees of contracture) was derived by asking
respondents to indicate what combination of attributes and levels
of the EQ-5D-5L proile most accurately relects the impact of
living with such hand. Conditional logistic models were used to
estimate indirect utilities, then rescaled to the anchor points on
the EQ-5D-5L.
Results Estimated utilities based on the responses of 1,745
qualiied respondents were 0.49, 0.57, and 0.63 for completely
affected dominant hands, non-dominant hands, or ambidextrous
hands, respectively. Utility for a dominant hand with 90-degree
contracture in t h e metacarpophalangeal joints of the ring and
little ingers was estimated to be 0.89. Separately, reducing the
contracture of metacarpophalangeal joint for a little inger from
50 to 12 degrees would improve utility by 0.02.
Interpretation DC is associated with substantial utility decrements.
The algorithms presented herein provide a robust and lexible
framework to assess utility for varying degrees of DC severity
The impact of venture capital on governance decisions in collaborations with start-ups
This article addresses solutions for contractual hazards in the formation and operation of collaborations with start-ups. We suggest that venture capitalists may serve as a mechanism to mitigate contractual hazards and act as a substitute for equity sharing in joint ventures. This article is to our knowledge the first to address the impact of venture capital (VC) on governance decisions for start-ups. We analyze 5405 bilateral collaborations from the SDC database for the period 2009-2014, and find that VC-backed firms are less likely to share equity in collaborations
Improved measurement of the reactor antineutrino flux and spectrum at Daya Bay
published_or_final_versio
Self-oligomerization regulates stability of survival motor neuron protein isoforms by sequestering an SCF<sup>Slmb</sup> degron
Spinal muscular atrophy (SMA) is caused by homozygous mutations in human SMN1. Expression of a duplicate gene (SMN2) primarily results in skipping of exon 7 and production of an unstable protein isoform, SMNΔ7. Although SMN2 exon skipping is the principal contributor to SMA severity, mechanisms governing stability of survival motor neuron (SMN) isoforms are poorly understood. We used a Drosophila model system and label-free proteomics to identify the SCFSlmb ubiquitin E3 ligase complex as a novel SMN binding partner. SCFSlmb interacts with a phosphor degron embedded within the human and fruitfly SMN YG-box oligomerization domains. Substitution of a conserved serine (S270A) interferes with SCFSlmb binding and stabilizes SMNΔ7. SMA-causing missense mutations that block multimerization of full-length SMN are also stabilized in the degron mutant background. Overexpression of SMNΔ7S270A, but not wild-type (WT) SMNΔ7, provides a protective effect in SMA model mice and human motor neuron cell culture systems. Our findings support a model wherein the degron is exposed when SMN is monomeric and sequestered when SMN forms higher-order multimers
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