2,200 research outputs found
Light bottom squark and gluino confront electroweak precision measurements
We address the compatibility of a light sbottom (mass 2\sim 5.5 \gev) and a
light gluino (mass 12\sim 16 \gev) with electroweak precision measurements.
Such light particles have been suggested to explain the observed excess in the
quark production cross section at the Tevatron. The electroweak observables
may be affected by the sbottom and gluino through the SUSY-QCD corrections to
the vertex. We examine, in addition to the SUSY-QCD corrections, the
electroweak corrections to the gauge boson propagators from the stop which are
allowed to be light from the SU(2) symmetry. We find that this scenario is
strongly disfavored from electroweak precision measurements unless the heavier
sbottom mass eigenstate is lighter than 180\gev and the left-right mixing in
the stop sector is sufficiently large. This implies that one of the stops
should be lighter than about 98\gev.Comment: 4 pages, revtex, 2 figures. Reference added, version to appear in
Phys.Rev.Let
Comparative Aspects of Splenic Microcirculatory Pathways in Mammals: The Region Bordering the White Pulp
Splenic microcorrosion casts prepared using minimal volumes of material show that most of the flow passes through the region bordering the white pulp. However, the nature of these microcirculatory pathways has received little attention. We have studied these in dog, cat, rat, mouse, and normal versus diseased human spleens. In all 5 species, a marginal sinus (MS) of anastomosing vascular spaces 5-10 μm thick lies between the white pulp and marginal zone (MZ). The morphology differs between species and the MS is absent in immune thrombocytopenia. The MS fills by circumferential flow before blood passes outward to the MZ. Many capillaries supply the MS and MZ, their arrangement and degree of branching differing among species. Capillaries never terminate within the reticulum of the white pulp. In immune thrombocytopenia, marked vascular hyperplasia occurs within white pulp and MZ. The perimarginal cavernous sinus plexus (PMCS), found in human, dog and rat, comprises large flattened spaces up to 300 μm x 1000 μmin area and 30-100 μm thick. It lies between the MZ and red pulp or directly adjacent to white pulp, and receives flow principally via the MZ. In sinusal spleens, the MS, MZ and PMCS are drained by open-ended venous sinuses. In non-sinusal spleens, the MS and MZ are drained by pulp venules. Approximately 90% of the splenic inflow passes through the region bordering the white pulp, bypassing the filtration beds of the red pulp. This suggests that immunologic functions of the spleen take precedence over the filtration of blood cellular elements in the red pulp
Irrigation water management under risk: an application to Cyprus
We provide empirical evidence that attitude towards risk is important when assessing the impact of conservation policies on production choices. We �first follow the approach used by
Antle (1987) which enables �flexible estimation of the stochastic technology without ad hoc specifi�cation of risk preferences. In a second step, the impact of water quotas on farmer decisions can be solved, using risk aversion and technology parameter estimates. Application is made on
a farm-level data-set from the agricultural region of Kiti in Cyprus
Declining discount rates
We ask whether the US government should replace its current discounting practices with a declining discount rate schedule, as the United Kingdom and France have done, or continue to discount the future at a constant exponential rate. We present the theoretical basis for a declining discount rate (DDR) schedule, but focus on how, in practice, a DDR could be estimated for use by policy analysts. We discuss the empirical approaches in the literature and review how the United Kingdom and France estimated their DDR schedules. We conclude with advice on how the United States might proceed to consider modifying its current discounting practices
Neutralino Dark Matter Elastic Scattering in a Flat and Accelerating Universe
In SUGRA inspired supersymmetric models with universal boundary conditions
for the soft masses, the scalar cross section for the elastic
neutralino--nucleon scattering is in general several orders of magnitude below
the sensitivity of current experiments. For large and low
values, the theoretically predicted can
approach the sensitivity of these experiments () being at
the same time in agreement with recent cosmological data, which impose severe
restrictions on the CDM relic density, and with accelerator experiments which
put lower bounds on sparticle and Higgs boson masses. Further improvement of
the sensitivity of DAMA and CDMS experiments will probe the large
region of the parameter space in the vicinity of the boundaries of the
parameter space allowed by chargino and Higgs searches.Comment: 15 pages, 9 figures. A note added; version to appear in MPL
Bimaximal Neutrino Mixing in a Zee-type Model with Badly Broken Flavor Symmetry
A Zee-type neutrino mass matrix model with a badly broken horizontal symmetry
SU(3)_H is investigated. By putting a simple ansatz on the symmetry breaking
effects of SU(3)_H for transition matrix elements, it is demonstrated that the
model can give a nearly bimaximal neutrino mixing with the ratio ,
which are in excellent agreement with the observed data. In the near future,
the lepton-number violating decay will be observed.Comment: 10 pages, no figures, a comment adde
Spatial Bi-hourly Variation of Alternaria Spore Concentration in Worcester, UK
Alternaria species are ubiquitous fungi affecting food security and human health. They are pathogenic on many economically important crops and allergenic to many sensitive people worldwide. Studies from Worcester, UK have shown high a concentration of Alternaria spores, most likely caused by agricultural activities. However, it is unknown whether Alternaria spore concentrations vary geographically throughout Worcestershire. An investigation on the spatial variation in bi-hourly concentration of Alternaria spores in Worcestershire during 2016 and 2017 was conducted. Spores were sampled using two Hirst-type Burkard spore traps at the University of Worcester. One on the rooftop of a building at St John’s Campus and another at Lakeside Campus approximately 7 km away. St John’s Campus is located in the centre of Worcester (52.1970, -2.2421), while Lakeside Campus is located in an agricultural environment (52.2537, -2.2535) with regularly cut grass in the near surroundings. Slides were counted using bi-hourly traverse at x 400 magnification. The total number of spores per slide were converted to the daily mean of spores m¯³ of air. There was a highly positive correlation in the concentration of Alternaria spores between the two sites in both 2016 and 2017. St John’s had the highest peak of spore concentration (213 m¯³) in 2016 and Lakeside had the peak concentration in 2017 (184 m¯³). Concentrations above 100 m¯³ of air were observed more frequently at Lakeside. The study revealed that Alternaria spore concentrations were higher at Lakeside than at St John’s. This could be attributed to spores released from either crops or agricultural activities (e.g. haying or harvesting) or from decomposed grass since the surrounding area is routinely managed. Further work in 2018 will include spore correlations with weather variables from a pair of weather stations located at each site, enabling studies caused by variations in weather and climate. Spatial variation in bi-hourly spore concentrations is useful information to atopic subjects, health experts and crop pathologists.
Keywords: Harvesting. Allergy. Fungal Spores
Constraints on Higher-Order Perturbative Corrections in Semileptonic Decays from Residual Renormalization-Scale Dependence
The constraint of a progressive decrease in residual renormalization scale
dependence with increasing loop order is developed as a method for obtaining
bounds on unknown higher-order perturbative corrections to
renormalization-group invariant quantities. This technique is applied to the
inclusive semileptonic process (explicitly known to
two-loop order) to obtain bounds on the three- and four-loop perturbative
coefficients that are not accessible via the renormalization group. Using the
principle of minimal sensitivity, an estimate is obtained for the perturbative
contributions to that incorporates
theoretical uncertainty from as-yet-undetermined higher order QCD corrections.Comment: latex2e using amsmath, 8 pages, 4 embedded eps figures. Revised
version contains an additional figure and accompanying revision
Quark and Lepton Mass Patterns and the Absolute Neutrino Mass Scale
We investigate what could be learned about the absolute scale of neutrino
masses from comparisons among the patterns within quark and lepton mass
hierarchies. First, we observe that the existing information on neutrino masses
fits quite well to the unexplained, but apparently present regularities in the
quark and charged lepton sectors. Second, we discuss several possible mass
patterns, pointing out that this quite generally leads towards hierarchical
neutrino mass patterns especially disfavoring the vacuum solution.Comment: final version to be published in PRD, 5 pages, 2 figures, RevTe
Study of Charmonia near the deconfining transition on an anisotropic lattice with O(a) improved quark action
We study hadron properties near the deconfining transition in the quenched
lattice QCD simulation. This paper focuses on the heavy quarkonium states, such
as meson. In order to treat heavy quarks at , we adopt the
improved Wilson action on anisotropic lattice. We discuss bound
state observing the wave function and compare the meson correlators at above
and below . Although we find a large change of correlator near the ,
the strong spatial correlation which is almost the same as confinement phase
survives even .Comment: 19 pages, 10 figure
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