6,135 research outputs found
Multifactorial analysis of human blood cell responses to clinical total body irradiation
Multiple regression analysis techniques are used to study the effects of therapeutic radiation exposure, number of fractions, and time on such quantal responses as tumor control and skin injury. The potential of these methods for the analysis of human blood cell responses is demonstrated and estimates are given of the effects of total amount of exposure and time of protraction in determining the minimum white blood cell concentration observed after exposure of patients from four disease groups
Dosimetry for radiobiological studies of the human hematopoietic system
A system for estimating individual bone marrow doses in therapeutic radiation exposures of leukemia patients was studied. These measurements are used to make dose response correlations and to study the effect of dose protraction on peripheral blood cell levels. Three irradiators designed to produce a uniform field of high energy gamma radiation for total body exposures of large animals and man are also used for radiobiological studies
Symmetry Analysis of Multiferroic Co_3TeO_6
A phenomenological explanation of the magnetoelectric behavior of Co_3TeO_6
is developed. We explain the second harmonic generation data and the magnetic
field induced spontaneous polarization in the magnetically ordered phase below
20K.Comment: Phys rev B Rapids, to appea
Axioms for signatures with domain and demonic composition
Demonic composition ∗ is an associative operation on binary relations, and demonic refinement ⊑ is a partial order on binary relations. Other operations on binary relations considered here include the unary domain operation D and the left restrictive multiplication operation ∘ given by s∘t=D(s)∗t. We show that the class of relation algebras of signature {⊑,D,∗}, or equivalently {⊆,∘,∗}, has no finite axiomatisation. A large number of other non-finite axiomatisability consequences of this result are also given, along with some further negative results for related signatures. On the positive side, a finite set of axioms is obtained for relation algebras with signature {⊑,∘,∗}, hence also for {⊆,∘,∗}
Intersexual conflict influences female reproductive success in a female-dispersing primate
In group-living mammals, individual efforts to maximize reproductive success result in conflicts and compromises between the sexes. Females utilize counterstrategies to minimize the costs of sexual coercion by males, but few studies have examined the effect of such behaviors on female reproductive success. Secondary dispersal by females is rare among group-living mammals, but in western gorillas, it is believed to be a mate choice strategy to minimize infanticide risk and infant mortality. Previous research suggested that females choose males that are good protectors. However, how much female reproductive success varies depending on male competitive ability and whether female secondary dispersal leads to reproductive costs or benefits has not been examined. We used data on 100 females and 229 infants in 36 breeding groups from a 20-year long-term study of wild western lowland gorillas to investigate whether male tenure duration and female transfer rate had an effect on interbirth interval, female birth rates, and offspring mortality. We found that offspring mortality was higher near the end of males’ tenures, even after excluding potential infanticide when those males died, suggesting that females suffer a reproductive cost by being with males nearing the end of their tenures. Females experience a delay in breeding when they dispersed, having a notable effect on birth rates of surviving offspring per female if females transfer multiple times in their lives. This study exemplifies that female counterstrategies to mitigate the effects of male-male competition and sexual coercion may not be sufficient to overcome the negative consequences of male behavior
Air Shower Simulation and Hadronic Interactions
The aim of this report of the Working Group on Hadronic Interactions and Air
Shower Simulation is to give an overview of the status of the field,
emphasizing open questions and a comparison of relevant results of the
different experiments. It is shown that an approximate overall understanding of
extensive air showers and the corresponding hadronic interactions has been
reached. The simulations provide a qualitative description of the bulk of the
air shower observables. Discrepancies are however found when the correlation
between measurements of the longitudinal shower profile are compared to that of
the lateral particle distributions at ground. The report concludes with a list
of important problems that should be addressed to make progress in
understanding hadronic interactions and, hence, improve the reliability of air
shower simulations.Comment: Working Group report given at UHECR 2012 Symposium, CERN, Feb. 2012.
Published in EPJ Web of Conferences 53, 01007 (2013
The Stochastic Dynamics of Rectangular and V-shaped Atomic Force Microscope Cantilevers in a Viscous Fluid and Near a Solid Boundary
Using a thermodynamic approach based upon the fluctuation-dissipation theorem
we quantify the stochastic dynamics of rectangular and V-shaped microscale
cantilevers immersed in a viscous fluid. We show that the stochastic cantilever
dynamics as measured by the displacement of the cantilever tip or by the angle
of the cantilever tip are different. We trace this difference to contributions
from the higher modes of the cantilever. We find that contributions from the
higher modes are significant in the dynamics of the cantilever tip-angle. For
the V-shaped cantilever the resulting flow field is three-dimensional and
complex in contrast to what is found for a long and slender rectangular
cantilever. Despite this complexity the stochastic dynamics can be predicted
using a two-dimensional model with an appropriately chosen length scale. We
also quantify the increased fluid dissipation that results as a V-shaped
cantilever is brought near a solid planar boundary.Comment: 10 pages, 15 images, corrected equation (8
Thin-film flow in helically wound rectangular channels with small torsion
Laminar gravity-driven thin-film flow down a helically-wound channel of rectangular cross-section with small torsion in which the fluid depth is small is considered. Neglecting the entrance and exit regions we obtain the steady-state solution that is independent of position along the axis of the channel, so that the flow, which comprises a primary flow in the direction of the axis of the channel and a secondary flow in the cross-sectional plane, depends only on position in the two-dimensional cross-section of the channel. A thin-film approximation yields explicit expressions for the fluid velocity and pressure in terms of the free-surface shape, the latter satisfying a non-linear ordinary differential equation that has a simple exact solution in the special case of a channel of rectangular cross-section. The predictions of the thin-film model are shown to be in good agreement with much more computationally intensive solutions of the small-helix-torsion Navier–Stokes equations. The present work has particular relevance to spiral particle separators used in the mineral-processing industry. The validity of an assumption commonly used in modelling flow in spiral separators, namely that the flow in the outer region of the separator cross-section is described by a free vortex, is shown to depend on the problem parameters
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