592 research outputs found
Apprenticeship migration to three pre-industrial English towns
Tudor and Stuart England was a mobile society. The generally
high levels of geographical mobility went hand in hand with various
degrees of social and occupational mobility. Some of the most
important movements were of people from the countryside to the town,
as they were significant as a transfer of resources and an agency
of social mobilitYJ their chronological and geographical flows
provide an index of both changing urban fortunes and of the levels
of spatial integration and economic development upon which these
changing fortunes were based. Amongst the types of rural-urban
migration, the movement of teenagers to a town to serve an
apprenticeship is a particularly valuable topic for study. The
training of labour is important in any society and in preindustrial
England output could only be raised in many industries
through a greater input of labour. The areas from which the
apprentices were drawn represent the scale of organisation, economic
social and spatial, current in sixteenth and seventeenth century England.
This gives an indication of the level of development of the country
as it underwent the transition from a society largely based on the
discrete daily and weekly contacts around the provincial central
places, through an increase in scale to a regional integration
based upon county towns, to a~hesive national system.
Three county towns were selected, Chester, Gloucester and
Shrewsbury, as they each had a good series of apprenticeship records;
they represented the foci characteristic of the regional scale of
integration and they were associated one with another along the
England-Wales border, thus forming a convenient spatial system. The
results of the study confirm the findings on mobility in sixteenth
and seventeenth century England. Most migrants moved over short
distances and a few made long journeys. The propensity to move
varied with the status of the apprentices' backgroundsJ generally
the higher the status the longer the distance moved. Many
apprentices trained in an occupation different to that of their
fathers and some of these represented a significant degree of social
mobility. Nevertheless, association within the s~me sub-group
was common, either based upon the same raw material or upon the
type of work undertaken. The three towns organised a regional
scale of integration around themselves, reinforcing their roles
as important suppliers of goods and services to their hinterlands,
the extent of which remained constant throughout the period studied
Fine Structure of Dark Matter Halos and its Effect on Terrestrial Detection Experiments
Terrestrial dark matter detection experiments probe the velocity-space
distribution of dark matter particles in the vicinity of the Earth. We present
a novel method, to be used in conjunction with standard cosmological
simulations of hierarchical clustering, that allows one to extract a truly
local velocity-space distribution in exquisite detail. Preliminary results
suggest a new picture for this distribution which is decidedly non-Maxwellian
but instead is characterized by randomly positioned peaks in velocity space. We
discuss the implications of these results for both WIMP and axion detection
experiments.Comment: 5 pages, 3 figure
Substructure in the Andromeda Galaxy Globular Cluster System
In the most prominent current scenario of galaxy formation, galaxies form
hierarchically through the merger of smaller systems. Such mergers could leave
behind dynamical signatures which may linger long after the event. In
particular, the globular cluster system (GCS) of a merging satellite galaxy may
remain as a distinct sub-population within the GCS of a massive galaxy. Using
the latest available globular cluster velocities and metallicities, we present
the results of a search for grouping in the GCS of our nearest large spiral
galaxy neighbor, M31. A modified friends-of-friends algorithm is used to
identify a number of possible merger remnants in projected position, radial
velocity and [Fe/H] parameter space. Numerical simulations are used to check
that such merger remnants are indeed plausible over the timescales of interest.
The identification of stellar streams associated with these groups is required
in order to confirm that they represent merger remnants.Comment: 19 pages, 3 figures, accepted for publication in the Ap
Plerixafor plus granulocyte colony-stimulating factor for patients with non-Hodgkin lymphoma and multiple myeloma: Long-term follow-up report
Internal jugular vein thrombosis in a warfarinised patient: a case report
<p>Abstract</p> <p>Introduction</p> <p>Internal jugular vein thrombosis (IJVT) is a rare but potentially fatal condition. It usually arises following trauma to the internal jugular vein but is also seen in association with coagulopathies and advanced malignancies as part of a para-neoplastic syndrome.</p> <p>Case presentation</p> <p>We report a case of a 44 year old woman with a strong past medical history and family history of thrombotic disease who presented with abdominal pain and ascites. A stage III ovarian carcinoma was diagnosed and she underwent debulking of the tumour. She sustained a peri-operative haemorrhage and required insertion of a central line into the right internal jugular vein. At one month follow-up she presented as an emergency with a left neck mass and painful swallowing. A duplex ultrasound of her neck identified a left IJVT to the level of the brachiocephalic vein which had occurred despite warfarinisation and an INR of greater than 2. She was commenced on intravenous heparin and the swelling resolved over the course of a week.</p> <p>Conclusion</p> <p>This case illustrates an unusual presentation of a rare condition. In this case, the precise aetiology is unclear as the IJVT may have been related to a coagulopathy or the presence of advanced malignancy and occurred despite adequate anticoagulation.</p
Solar Wakes of Dark Matter Flows
We analyze the effect of the Sun's gravitational field on a flow of cold dark
matter (CDM) through the solar system in the limit where the velocity
dispersion of the flow vanishes. The exact density and velocity distributions
are derived in the case where the Sun is a point mass. The results are extended
to the more realistic case where the Sun has a finite size spherically
symmetric mass distribution. We find that regions of infinite density, called
caustics, appear. One such region is a line caustic on the axis of symmetry,
downstream from the Sun, where the flow trajectories cross. Another is a
cone-shaped caustic surface near the trajectories of maximum scattering angle.
The trajectories forming the conical caustic pass through the Sun's interior
and probe the solar mass distribution, raising the possibility that the solar
mass distribution may some day be measured by a dark matter detector on Earth.
We generalize our results to the case of flows with continuous velocity
distributions, such as that predicted by the isothermal model of the Milky Way
halo.Comment: 30 pages, 8 figure
The phase-space structure of a dark-matter halo: Implications for dark-matter direct detection experiments
We study the phase-space structure of a dark-matter halo formed in a high
resolution simulation of a Lambda CDM cosmology. Our goal is to quantify how
much substructure is left over from the inhomogeneous growth of the halo, and
how it may affect the signal in experiments aimed at detecting the dark matter
particles directly. If we focus on the equivalent of ``Solar vicinity'', we
find that the dark-matter is smoothly distributed in space. The probability of
detecting particles bound within dense lumps of individual mass less than 10^7
M_\sun h^{-1} is small, less than 10^{-2}. The velocity ellipsoid in the Solar
neighbourhood deviates only slightly from a multivariate Gaussian, and can be
thought of as a superposition of thousands of kinematically cold streams. The
motions of the most energetic particles are, however, strongly clumped and
highly anisotropic. We conclude that experiments may safely assume a smooth
multivariate Gaussian distribution to represent the kinematics of dark-matter
particles in the Solar neighbourhood. Experiments sensitive to the direction of
motion of the incident particles could exploit the expected anisotropy to learn
about the recent merging history of our Galaxy.Comment: 13 pages, 13 figures, Phys. Rev. D in press. Postscript version with
high resolution figures available from
http://www.mpa-garching.mpg.de/~ahelmi/research/lcdm_dm.html; some changes in
the text; constraints on the effect of bound dark-matter lumps revised;
remaining conclusions unchange
Effect of halo modelling on WIMP exclusion limits
WIMP direct detection experiments are just reaching the sensitivity required
to detect galactic dark matter in the form of neutralinos. Data from these
experiments are usually analysed under the simplifying assumption that the
Milky Way halo is an isothermal sphere with maxwellian velocity distribution.
Observations and numerical simulations indicate that galaxy halos are in fact
triaxial and anisotropic. Furthermore, in the cold dark matter paradigm
galactic halos form via the merger of smaller subhalos, and at least some
residual substructure survives. We examine the effect of halo modelling on WIMP
exclusion limits, taking into account the detector response. Triaxial and
anisotropic halo models, with parameters motivated by observations and
numerical simulations, lead to significant changes which are different for
different experiments, while if the local WIMP distribution is dominated by
small scale clumps then the exclusion limits are changed dramatically.Comment: 9 pages, 9 figures, version to appear in Phys. Rev. D, minor change
Mutations in pericentrin cause Seckel syndrome with defective ATR-dependent DNA damage signaling
Large brain size is one of the defining characteristics of modern humans. Seckel syndrome (MIM 210600), a disorder of markedly reduced brain and body size, is associated with defective ATR-dependent DNA damage signaling. Only a single hypomorphic mutation of ATR has been identified in this genetically heterogeneous condition. We now report that mutations in the gene encoding pericentrin (PCNT)--resulting in the loss of pericentrin from the centrosome, where it has key functions anchoring both structural and regulatory proteins--also cause Seckel syndrome. Furthermore, we find that cells of individuals with Seckel syndrome due to mutations in PCNT (PCNT-Seckel) have defects in ATR-dependent checkpoint signaling, providing the first evidence linking a structural centrosomal protein with DNA damage signaling. These findings also suggest that other known microcephaly genes implicated in either DNA repair responses or centrosomal function may act in common developmental pathways determining human brain and body size
Long-term health effects after resolution of acute Cryptosporidium parvum infection: a 1-year follow-up of outbreak-associated cases
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