1,689 research outputs found
The Rhesus Factor and Disease Prevention
First published by the Wellcome Trust Centre
for the History of Medicine at UCL, 2004. Β©The Trustee of the Wellcome Trust, London, 2004. All volumes are freely available online at: www.history.qmul.ac.uk/research/modbiomed/wellcome_witnesses/Annotated and edited transcript of a Witness Seminar held on 3 June 2003. Introduction by Professor Doris T Zallen.Annotated and edited transcript of a Witness Seminar held on 3 June 2003. Introduction by Professor Doris T Zallen.Annotated and edited transcript of a Witness Seminar held on 3 June 2003. Introduction by Professor Doris T Zallen.Annotated and edited transcript of a Witness Seminar held on 3 June 2003. Introduction by Professor Doris T Zallen.Annotated and edited transcript of a Witness Seminar held on 3 June 2003. Introduction by Professor Doris T Zallen.Annotated and edited transcript of a Witness Seminar held on 3 June 2003. Introduction by Professor Doris T Zallen.Consists of the edited transcripts of Witness SeThe prevention of rhesus disease of the newborn is a stunning medical success story. This disease afflicted thousands of newborns each year, causing serious health problems, even death. Yet from the early 1940s to the 1970s β British and American researchers uncovered the basis of the disease and developed the medical intervention that could prevent its occurrence. Many of the key steps leading to this remarkable achievement took place at the University of Liverpool School of Medicine. Chaired by Professor Sir David Weatherall, this Witness Seminar examines the factors that triggered these studies and the challenges that confronted scientists and clinicians; the intellectual, institutional, and social factors that guided the work; the crucial insights; and the vistas that the prevention of rhesus disease has opened in fetal medicine. Participants include Professor Robin Coombs, the late Professor Ronald Finn, Dr Nevin Hughes-Jones, Professor Patrick Mollison, Dr Archie Norman, Dr Derrick Tovey, Professor Charles Whitfield, Professor John Woodrow and Professor Doris Zallen. Zallen, D T, Christie D A, Tansey E M. (eds) (2004) The Rhesus factor and disease prevention, Wellcome Witnesses to Twentieth Century Medicine, vol. 22. London: The Wellcome Trust Centre for the History of Medicine at UCL. ISBN 978 0 85484 099 1minars organized by the History of Twentieth Century Medicine Group and held at the Wellcome Institute for the History of Medicine.The Wellcome Trust Centre for the History of Medicine at University College London is funded by the Wellcome Trust,which is a registered charity, no. 210183
Equilibrium and non-equilibrium fluctuations in a glass-forming liquid
Glass-forming liquids display strong fluctuations -- dynamical
heterogeneities -- near their glass transition. By numerically simulating a
binary Weeks-Chandler-Andersen liquid and varying both temperature and
timescale, we investigate the probability distributions of two kinds of local
fluctuations in the non-equilibrium (aging) regime and in the equilibrium
regime; and find them to be very similar in the two regimes and across
temperatures. We also observe that, when appropriately rescaled, the integrated
dynamic susceptibility is very weakly dependent on temperature and very similar
in both regimes.Comment: v1: 5 pages, 4 figures v2: 5 pages, 4 figures. Now includes results
at three temperatures, two of them above T_{MCT} and one below T_{MCT}; and
more extensive discussion of connections to experiment
Integrating New Values with Old Uses in the Relicensing of Kingsley Dam and Related Facilities (Making Part of the Problem a Part of the Solution)
21 pages (includes illustrations and map)
Integrating New Values with Old Uses in the Relicensing of Kingsley Dam and Related Facilities (Making Part of the Problem a Part of the Solution)
21 pages (includes illustrations and map)
Scaled frequency-dependent transport in the mesoscopically phase-separated colossal magnetoresistive manganite La_{0.625-y}Pr_yCa_{0.375}MnO_3
We address the issue of massive phase separation (PS) in manganite family of
doped Mott insulators through ac conductivity measurements on
LaPrCaMnO (0.375 y 0.275), and
establish applicability of the scaling theory of percolation in the critical
regime of the PS. Measurements of dc resistivity, magnetization (M(T)) and
electron diffraction show incomplete growth of a ferromagnetic (FM) metallic
component on cooling the high temperature charge ordered (CO) phase well below
Curie temperature. The impedance Z(T,f) measured over a frequency
(f) range of 10 Hz to 10 MHz in the critical regime follows a universal scaling
of the form R(T,0)g(f) with 0.86
and the normalized correlation length varying from 1 to 4, suggesting anomalous
diffusion of holes in percolating FM clusters.Comment: 12 pages and 5 figure
Spectral responses in granular compaction
The slow compaction of a gently tapped granular packing is reminiscent of the
low-temperature dynamics of structural and spin glasses. Here, I probe the
dynamical spectrum of granular compaction by measuring a complex
(frequency-dependent) volumetric susceptibility . While the
packing density displays glass-like slow relaxations (aging) and
history-dependence (memory) at low tapping amplitudes, the susceptibility
displays very weak aging effects, and its spectrum shows no
sign of a rapidly growing timescale. These features place in
sharp contrast to its dielectric and magnetic counterparts in structural and
spin glasses; instead, bears close similarities to the complex
specific heat of spin glasses. This, I suggest, indicates the glass-like
dynamics in granular compaction are governed by statistically rare relaxation
processes that become increasingly separated in timescale from the typical
relaxations of the system. Finally, I examine the effect of finite system size
on the spectrum of compaction dynamics. Starting from the ansatz that low
frequency processes correspond to large scale particle rearrangements, I
suggest the observed finite size effects are consistent with the suppression of
large-scale collective rearrangements in small systems.Comment: 18 pages, 17 figures. Submitted to PR
Patterned Gene Expression Directs Bipolar Planar Polarity in Drosophila
AbstractDuring convergent extension in Drosophila, polarized cell movements cause the germband to narrow along the dorsal-ventral (D-V) axis and more than double in length along the anterior-posterior (A-P) axis. This tissue remodeling requires the correct patterning of gene expression along the A-P axis, perpendicular to the direction of cell movement. Here, we demonstrate that A-P patterning information results in the polarized localization of cortical proteins in intercalating cells. In particular, cell fate differences conferred by striped expression of the even-skipped and runt pair-rule genes are both necessary and sufficient to orient planar polarity. This polarity consists of an enrichment of nonmuscle myosin II at A-P cell borders and Bazooka/PAR-3 protein at the reciprocal D-V cell borders. Moreover, bazooka mutants are defective for germband extension. These results indicate that spatial patterns of gene expression coordinate planar polarity across a multicellular population through the localized distribution of proteins required for cell movement
Exact Constructions of a Family of Dense Periodic Packings of Tetrahedra
The determination of the densest packings of regular tetrahedra (one of the
five Platonic solids) is attracting great attention as evidenced by the rapid
pace at which packing records are being broken and the fascinating packing
structures that have emerged. Here we provide the most general analytical
formulation to date to construct dense periodic packings of tetrahedra with
four particles per fundamental cell. This analysis results in six-parameter
family of dense tetrahedron packings that includes as special cases recently
discovered "dimer" packings of tetrahedra, including the densest known packings
with density . This study strongly suggests that
the latter set of packings are the densest among all packings with a
four-particle basis. Whether they are the densest packings of tetrahedra among
all packings is an open question, but we offer remarks about this issue.
Moreover, we describe a procedure that provides estimates of upper bounds on
the maximal density of tetrahedron packings, which could aid in assessing the
packing efficiency of candidate dense packings.Comment: It contains 25 pages, 5 figures
Elasticity of highly cross-linked random networks
Starting from a microscopic model of randomly cross-linked particles with
quenched disorder, we calculate the Laudau-Wilson free energy S for arbitrary
cross-link densities. Considering pure shear deformations, S takes the form of
the elastic energy of an isotropic amorphous solid state, from which the shear
modulus can be identified. It is found to be an universal quantity, not
depending on any microscopic length-scales of the model.Comment: 6 pages, 5 figure
- β¦