2,794 research outputs found
The Royal Medical Society To-day
We have often heard that our University, with its paucity of halls of residence and common rooms used for the right purpose, is fast developing the atmosphere of a huge and impersonal technical college. The undergraduate, his brain dulled by the heavy aroma of haddock, emerges each morning from his “digs”. He returns in the early evening to decipher a sheaf of laboriously scribbled notes that might even be headed by the “good morning, ladies and gentlemen” with which his lecturer aroused him from complete coma into the semi-conscious state in which the rest of his day is spent. He has contributed nothing to, and has gained nothing from his day at the “University.
Standard Model stability bounds for new physics within LHC reach
We analyse the stability lower bounds on the Standard Model Higgs mass by
carefully controlling the scale independence of the effective potential. We
include resummed leading and next-to-leading-log corrections, and physical pole
masses for the Higgs boson, M_H, and the top-quark, M_t. Particular attention
is devoted to the cases where the scale of new physics \Lambda is within LHC
reach, i.e. \Lambda\leq 10 TeV, which have been the object of recent
controversial results. We clarify the origin of discrepancies and confirm our
earlier results within the error of our previous estimate. In particular for
\Lambda=1 TeV we find that
M_H[GeV]>52+0.64(M_t[GeV]-175)-0.50\frac{\alpha_s(M_Z)-0.118}{0.006}.
For fixed values of M_t and \alpha_s(M_Z), the error from higher effects, as
the lack of exact scale invariance of the effective potential and higher-order
radiative corrections, is conservatively estimated to be \simlt 5 GeV.Comment: 17 pages, latex + psfig.sty, 4 figure
Multibeam Maser Survey of methanol and excited OH in the Magellanic clouds: new detections and maser abundance estimates
‘The definitive version is available at www.blackwell-synergy.com.’ Copyright Blackwell Publishing DOI: 10.1111/j.1365-2966.2008.12888.xPeer reviewe
Asymptotic description of transients and synchronized states of globally coupled oscillators
A two-time scale asymptotic method has been introduced to analyze the
multimodal mean-field Kuramoto-Sakaguchi model of oscillator synchronization in
the high-frequency limit. The method allows to uncouple the probability density
in different components corresponding to the different peaks of the oscillator
frequency distribution. Each component evolves toward a stationary state in a
comoving frame and the overall order parameter can be reconstructed by
combining them. Synchronized phases are a combination of traveling waves and
incoherent solutions depending on parameter values. Our results agree very well
with direct numerical simulations of the nonlinear Fokker-Planck equation for
the probability density. Numerical results have been obtained by finite
differences and a spectral method in the particular case of bimodal (symmetric
and asymmetric) frequency distribution with or without external field. We also
recover in a very easy and intuitive way the only other known analytical
results: those corresponding to reflection-symmetric bimodal frequency
distributions near bifurcation points.Comment: Revtex,12 pag.,9 fig.;submitted to Physica
Reducing stomatal density in barley improves drought tolerance without impacting on yield.
The epidermal patterning factor (EPF) family of secreted signalling peptides regulate the frequency of stomatal development in model dicot and basal land plant species. Here we identify and manipulate the expression of a barley ortholog and demonstrate that when overexpressed HvEPF1 limits entry to, and progression through, the stomatal development pathway. Despite substantial reductions in leaf gas exchange, barley plants with approximately half of the normal number of stomata show no reductions in grain yield. In addition, HvEPF1OE barley lines exhibit significantly enhanced water use efficiency, drought tolerance and soil water conservation properties. Our results demonstrate the potential of manipulating stomatal frequency for the protection and optimisation of cereal crop yields under future drier environments
Self-assembly mechanism in colloids: perspectives from Statistical Physics
Motivated by recent experimental findings in chemical synthesis of colloidal
particles, we draw an analogy between self-assembly processes occurring in
biological systems (e.g. protein folding) and a new exciting possibility in the
field of material science. We consider a self-assembly process whose elementary
building blocks are decorated patchy colloids of various types, that
spontaneously drive the system toward a unique and predetermined targeted
macroscopic structure.
To this aim, we discuss a simple theoretical model -- the Kern-Frenkel model
-- describing a fluid of colloidal spherical particles with a pre-defined
number and distribution of solvophobic and solvophilic regions on their
surface. The solvophobic and solvophilic regions are described via a
short-range square-well and a hard-sphere potentials, respectively.
Integral equation and perturbation theories are presented to discuss
structural and thermodynamical properties, with particular emphasis on the
computation of the fluid-fluid (or gas-liquid) transition in the
temperature-density plane.
The model allows the description of both one and two attractive caps, as a
function of the fraction of covered attractive surface, thus interpolating
between a square-well and a hard-sphere fluid, upon changing the coverage.
By comparison with Monte Carlo simulations, we assess the pros and the cons
of both integral equation and perturbation theories in the present context of
patchy colloids, where the computational effort for numerical simulations is
rather demanding.Comment: 14 pages, 7 figures, Special issue for the SigmaPhi2011 conferenc
Micro-LED nanosecond pulsed structured light sources with 405 nm – 510 nm wavelength
Narrow-pulse visible light sources are crucial to time-resolved imaging. We present 16k-element MicroLED arrays spanning the visible region allowed by InGaN/GaN, achieving 3 ns pulses at up to 100 MHz repetition rate with programmable illumination patterns
Warehouse design and planning: A mathematical programming approach
The dynamic nature of today's competitive markets compels organizations to an incessant reassessment in an effort to respond to continuous challenges. Therefore, warehouses as an important link in most supply chains, must be continually re-evaluated to ensure that they are consistent with both market's demands and management's strategies. A number of warehouse decision support models have been proposed in the literature but considerable difficulties in applying these models still remain, due to the large amount of information to be processed and to the large number of possible alternatives. In this paper we discuss a mathematical programming model aiming to support some warehouse management and inventory decisions. In particular a large mixed-integer nonlinear programming model (MINLP) is presented to capture the trade-offs among the different inventory and warehouse costs in order to achieve global optimal design satisfying throughput requirements.(undefined)info:eu-repo/semantics/publishedVersio
Improved Higgs Mass Stability Bound in the Standard Model and Implications for Supersymmetry
We re-examine the lower bound on the mass of the Higgs boson, , from
Standard Model vacuum stability including next-to-leading-log radiative
corrections. This amounts to work with the full one-loop effective potential,
, improved by two-loop RGE, and allows to keep control of the scale
invariance of in a wide range of the -field. Our results show that
the bound is less stringent than in previous estimates.
In addition we perform a detailed comparison between the SM lower bounds on
and the supersymmetric upper bounds on it. It turns out that depending on
the actual value of the top mass, , the eventually measured Higgs mass can
discard the pure SM, the Minimal Supersymmetric Standard Model or both.Comment: 11 pages + 7 postscript figures appended at the end, Latex,
IEM-FT-93/9
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