406 research outputs found
Model-independent constraints on spin observables
We discuss model-independent constraints on spin observables in exclusive and
inclusive reactions, with special attention to the case of photoproduction.Comment: 6 pages, 5 figures, Talk by J.-M. Richard at NSTAR 2009, IHEP,
Beijing (China), April 19-22, 2009, Proc. to appear in "Chinese Physics C
A Possibility to Observe Short-Range NN Properties in the Deuteron Breakup
Quasi-binary reaction of the deuteron breakup with the final
proton-proton pair in the
state is analyzed at initial energies GeV in the kinematics
of backward elastic pd-scattering . On the basis of the main
mechanisms of the process, including initial and final state
interaction, we show that unpolarized cross section and spin observables of
this reaction exhibit important properties of the half-off-shell
-scattering amplitude, which are relevant to the nucleon-nucleon
interaction at short distances.Comment: 9 pages, Latex, 3 Postscript figure
The effect of skin fatty acids on Staphylococcus aureus
Staphylococcus aureus is a commensal of the human nose and skin. Human skin fatty acids, in particular cis-6-hexadecenoic acid (C-6-H), have high antistaphylococcal activity and can inhibit virulence determinant production. Here, we show that sub-MIC levels of C-6-H result in induction of increased resistance. The mechanism(s) of C-6-H activity was investigated by combined transcriptome and proteome analyses. Proteome analysis demonstrated a pleiotropic effect of C-6-H on virulence determinant production. In response to C-6-H, transcriptomics revealed altered expression of over 500 genes, involved in many aspects of virulence and cellular physiology. The expression of toxins (hla, hlb,hlgBC) was reduced, whereas that of host defence evasion components (cap, sspAB, katA) was increased. In particular, members of the SaeRS regulon had highly reduced expression, and the use of specific mutants revealed that the effect on toxin production is likely mediated via SaeRS
Wagin-Woodanilling (zone 5) : catchment appraisal 2005
The aim of this report is to assess the current extent of salinity and other natural resource degradation issues and provide landholders with the best current management options to address natural resource management issues and enhance sustainable agricultural production
Tensor polarization of deuterons passing through matter
It is shown that the magnitude of tensor polarization of the deuteron beam,
which arises owing to the spin dichroism effect, depends appreciably on the
angular width of the detector that registers the deuterons transmitted through
the target. Even when the angular width of the detector is much smaller than
the mean square angle of multiple Coulomb scattering, the beam's tensor
polarization depends noticeably on rescattering. When the angular width of the
detector is much larger than the mean square angle of multiple Coulomb
scattering (as well as than the characteristic angle of elastic nuclear
scattering), tensor polarization is determined only by the total reaction cross
sections for deuteron-nucleus interaction, and elastic scattering processes
make no contribution to tensor polarization.Comment: 18 pages, 3 figures, to be published in IO
Bistability of Slow and Fast Traveling Waves in Fluid Mixtures
The appearence of a new type of fast nonlinear traveling wave states in
binary fluid convection with increasing Soret effect is elucidated and the
parameter range of their bistability with the common slower ones is evaluated
numerically. The bifurcation behavior and the significantly different
spatiotemporal properties of the different wave states - e.g. frequency, flow
structure, and concentration distribution - are determined and related to each
other and to a convenient measure of their nonlinearity. This allows to derive
a limit for the applicability of small amplitude expansions. Additionally an
universal scaling behavior of frequencies and mixing properties is found.
PACS: 47.20.-k, 47.10.+g, 47.20.KyComment: 4 pages including 5 Postscript figure
Pulsed Feedback Defers Cellular Differentiation
Environmental signals induce diverse cellular differentiation programs. In certain systems, cells defer differentiation for extended time periods after the signal appears, proliferating through multiple rounds of cell division before committing to a new fate. How can cells set a deferral time much longer than the cell cycle? Here we study Bacillus subtilis cells that respond to sudden nutrient limitation with multiple rounds of growth and division before differentiating into spores. A well-characterized genetic circuit controls the concentration and phosphorylation of the master regulator Spo0A, which rises to a critical concentration to initiate sporulation. However, it remains unclear how this circuit enables cells to defer sporulation for multiple cell cycles. Using quantitative time-lapse fluorescence microscopy of Spo0A dynamics in individual cells, we observed pulses of Spo0A phosphorylation at a characteristic cell cycle phase. Pulse amplitudes grew systematically and cell-autonomously over multiple cell cycles leading up to sporulation. This pulse growth required a key positive feedback loop involving the sporulation kinases, without which the deferral of sporulation became ultrasensitive to kinase expression. Thus, deferral is controlled by a pulsed positive feedback loop in which kinase expression is activated by pulses of Spo0A phosphorylation. This pulsed positive feedback architecture provides a more robust mechanism for setting deferral times than constitutive kinase expression. Finally, using mathematical modeling, we show how pulsing and time delays together enable “polyphasic” positive feedback, in which different parts of a feedback loop are active at different times. Polyphasic feedback can enable more accurate tuning of long deferral times. Together, these results suggest that Bacillus subtilis uses a pulsed positive feedback loop to implement a “timer” that operates over timescales much longer than a cell cycle
The feasibility of brief dog assisted therapy on university students stress levels: The PAwS study.
Background: Pet therapy is becoming increasingly popular and is used in a variety of ways from encouraging communication in older adults to improving wellbeing in those with serious mental illness. Increasingly Universities have been offering pet therapy to students in an effort to reduce stress. However, little evidence currently exists to support the effectiveness of reducing measurable stress levels after a standalone drop-in unstructured session. The University of Sheffield’s Counselling Service works in partnership with Guide Dogs for the Blind to give students access to calm, well-trained animals for informal group stress relief.
Aims: To assess the feasibility of implementing and evaluating unstructured group interventions with a Guide Dog in training within the university student population.
Methods: One hundred and thirty-one students who attended pet therapy at the University Counselling Service were recruited on a voluntary basis to take part in the research. Stress, measured on the state trait anxiety inventory, and blood pressure were taken before and after a 15-min intervention.
Results: All measures showed a statistically significant reduction immediately after the intervention.
Conclusion: Short interactions with a Guide Dog in training appear to reduce stress in University students. A controlled study is required to investigate further
The detection of neutron clusters
A new approach to the production and detection of bound neutron clusters is
presented. The technique is based on the breakup of beams of very neutron-rich
nuclei and the subsequent detection of the recoiling proton in a liquid
scintillator. The method has been tested in the breakup of 11Li, 14Be and 15B
beams by a C target. Some 6 events were observed that exhibit the
characteristics of a multineutron cluster liberated in the breakup of 14Be,
most probably in the channel 10Be+4n. The various backgrounds that may mimic
such a signal are discussed in detail.Comment: 11 pages, 12 figures, LPCC 01-1
Polarization transfer in the O reaction at forward angles and structure of the spin-dipole resonances
Cross sections and polarization transfer observables in the O
reactions at 392 MeV were measured at several angles between
0 and 14. The non-spin-flip () and spin-flip
() strengths in transitions to several discrete states and broad
resonances in O were extracted using a model-independent method. The
giant resonances in the energy region of 27 MeV were found to be
predominantly excited by transitions. The strength distribution
of spin-dipole transitions with and were deduced.
The obtained distribution was compared with a recent shell model calculation.
Experimental results are reasonably explained by distorted-wave impulse
approximation calculations with the shell model wave functions.Comment: 28 pages RevTex, including 9 figures, to be published in Phys. Rev.
C.; a typo in Eq. (3b) was correcte
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