288 research outputs found
Next-to-leading Corrections to the Higgs Boson Transverse Momentum Spectrum in Gluon Fusion
We present a fully analytic calculation of the Higgs boson transverse
momentum and rapidity distributions, for nonzero Higgs , at
next-to-leading order in the infinite-top-mass approximation. We separate the
cross section into a part that contains the dominant soft, virtual, collinear,
and small--enhanced contributions, and the remainder, which is
organized by the contributions due to different parton helicities. We use this
cross section to investigate analytically the small- limit and compare
with the expectation from the resummation of large logarithms of the type
. We also compute numerically the cross section at moderate
where a fixed-order calculation is reliable. We find a -factor
that varies from , and a reduction in the scale dependence, as
compared to leading order. Our analysis suggests that the contribution of
current parton distributions to the total uncertainty on this cross section at
the LHC is probably less than that due to uncalculated higher orders.Comment: 40 pages, 10 figures, JHEP style (minor changes, added reference
Dijet Production at Large Rapidity Intervals
We examine dijet production at large rapidity intervals at Tevatron energies,
by using the theory of Lipatov and collaborators which resums the leading
powers of the rapidity interval. We analyze the growth of the Mueller-Navelet
-factor in this context and find it to be negligible. However, we do find a
considerable enhancement of jet production at large transverse momenta. In
addition, we show that the correlation in transverse momentum and azimuthal
angle of the tagging jets fades away as the rapidity interval is increased.Comment: 12 pages, preprint DESY 93-139, SCIPP 93/3
Transmission of Human and Macaque Plasmodium spp. to Ex-Captive Orangutans in Kalimantan, Indonesia
We identified 4 discrete Plasmodium spp. sequences from the blood of orangutans, including 1 of P. vivax, which has implications for human residents and orangutan rehabilitation programs
Lattice Dynamics and the High Pressure Equation of State of Au
Elastic constants and zone-boundary phonon frequencies of gold are calculated
by total energy electronic structure methods to twofold compression. A
generalized force constant model is used to interpolate throughout the
Brillouin zone and evaluate moments of the phonon distribution. The moments are
used to calculate the volume dependence of the Gruneisen parameter in the fcc
solid. Using these results with ultrasonic and shock data, we formulate the
complete free energy for solid Au. This free energy is given as a set of closed
form expressions, which are valid to compressions of at least V/V_0 = 0.65 and
temperatures up to melting. Beyond this density, the Hugoniot enters the
solid-liquid mixed phase region. Effects of shock melting on the Hugoniot are
discussed within an approximate model. We compare with proposed standards for
the equation of state to pressures of ~200 GPa. Our result for the room
temperature isotherm is in very good agreement with an earlier standard of
Heinz and Jeanloz.Comment: 13 pages, 8 figures. Accepted by Phys. Rev.
Complementary approaches to understanding the plant circadian clock
Circadian clocks are oscillatory genetic networks that help organisms adapt
to the 24-hour day/night cycle. The clock of the green alga Ostreococcus tauri
is the simplest plant clock discovered so far. Its many advantages as an
experimental system facilitate the testing of computational predictions.
We present a model of the Ostreococcus clock in the stochastic process
algebra Bio-PEPA and exploit its mapping to different analysis techniques, such
as ordinary differential equations, stochastic simulation algorithms and
model-checking. The small number of molecules reported for this system tests
the limits of the continuous approximation underlying differential equations.
We investigate the difference between continuous-deterministic and
discrete-stochastic approaches. Stochastic simulation and model-checking allow
us to formulate new hypotheses on the system behaviour, such as the presence of
self-sustained oscillations in single cells under constant light conditions.
We investigate how to model the timing of dawn and dusk in the context of
model-checking, which we use to compute how the probability distributions of
key biochemical species change over time. These show that the relative
variation in expression level is smallest at the time of peak expression,
making peak time an optimal experimental phase marker. Building on these
analyses, we use approaches from evolutionary systems biology to investigate
how changes in the rate of mRNA degradation impacts the phase of a key protein
likely to affect fitness. We explore how robust this circadian clock is towards
such potential mutational changes in its underlying biochemistry. Our work
shows that multiple approaches lead to a more complete understanding of the
clock
Round-the-clock performance of coronary CT angiography for suspected acute coronary syndrome: Results from the BEACON trial
Objective: To assess the image quality of coronary CT angiography (CCTA) for suspected acute coronary syndrome (ACS) outside office hours. Methods: Patients with symptoms suggestive of an ACS underwent CCTA at the emergency department 24 hours, 7 days a week. A total of 118 patients, of whom 89 (75 %) presented during office hours (weekdays between 07:00 and 17:00) and 29 (25 %) outside office hours (weekdays between 17:00 and 07:00, weekends and holidays) underwent CCTA. Image quality was evaluated per coronary segment by two experienced readers and graded on an ordinal scale ranging from 1 to 3. Results: There were no significant differences in acquisition parameters, beta-blocker administration or heart rate between patients presenting during office hours and outside office hours. The median quality score per patient was 30.5 [interquartile range 26.0–33.5] for patients presenting during office hours in comparison to 27.5 [19.75–32.0] for patients presenting outside office hours (p=0.043). The number of non-evaluable segments was lower for patients presenting during office hours (0 [0–1.0] vs. 1.0 [0–4.0], p=0.009). Conclusion: Image quality of CCTA outside office hours in the diagnosis of suspected ACS is diminished. Key Points: • Quality scores were higher for coronary-CTA during office hours.• There were no differences in acquisition parameters.• There was a non-significant trend towards higher heart rates outside office hours.• Coronary-CTA on the ED requires state-of-the-art scanner technology and sufficiently trained staff.• Coronary-CTA on the ED needs preparation time and optimisation o
An organelle-specific protein landscape identifies novel diseases and molecular mechanisms
Contains fulltext :
158967.pdf (publisher's version ) (Open Access)Cellular organelles provide opportunities to relate biological mechanisms to disease. Here we use affinity proteomics, genetics and cell biology to interrogate cilia: poorly understood organelles, where defects cause genetic diseases. Two hundred and seventeen tagged human ciliary proteins create a final landscape of 1,319 proteins, 4,905 interactions and 52 complexes. Reverse tagging, repetition of purifications and statistical analyses, produce a high-resolution network that reveals organelle-specific interactions and complexes not apparent in larger studies, and links vesicle transport, the cytoskeleton, signalling and ubiquitination to ciliary signalling and proteostasis. We observe sub-complexes in exocyst and intraflagellar transport complexes, which we validate biochemically, and by probing structurally predicted, disruptive, genetic variants from ciliary disease patients. The landscape suggests other genetic diseases could be ciliary including 3M syndrome. We show that 3M genes are involved in ciliogenesis, and that patient fibroblasts lack cilia. Overall, this organelle-specific targeting strategy shows considerable promise for Systems Medicine
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