63 research outputs found
Tuberculosis in Dr Granville's mummy: a molecular re-examination of the earliest known Egyptian mummy to be scientifically examined and given a medical diagnosis
‘Dr Granville's mummy’ was described to the Royal Society of London in 1825 and was the first ancient Egyptian mummy to be subjected to a scientific autopsy. The remains are those of a woman, Irtyersenu, aged about 50, from the necropolis of Thebes and dated to about 600 BC. Augustus Bozzi Granville (1783–1872), an eminent physician and obstetrician, described many organs still in situ and attributed the cause of death to a tumour of the ovary. However, subsequent histological investigations indicate that the tumour is a benign cystadenoma. Histology of the lungs demonstrated a potentially fatal pulmonary exudate and earlier studies attempted to associate this with particular disease conditions. Palaeopathology and ancient DNA analyses show that tuberculosis was widespread in ancient Egypt, so a systematic search for tuberculosis was made, using specific DNA and lipid biomarker analyses. Clear evidence for Mycobacterium tuberculosis complex DNA was obtained in lung tissue and gall bladder samples, based on nested PCR of the IS6110 locus. Lung and femurs were positive for specific M. tuberculosis complex cell-wall mycolic acids, demonstrated by high-performance liquid chromatography of pyrenebutyric acid–pentafluorobenzyl mycolates. Therefore, tuberculosis is likely to have been the major cause of death of Irtyersenu
Finite covers of random 3-manifolds
A 3-manifold is Haken if it contains a topologically essential surface. The
Virtual Haken Conjecture posits that every irreducible 3-manifold with infinite
fundamental group has a finite cover which is Haken. In this paper, we study
random 3-manifolds and their finite covers in an attempt to shed light on this
difficult question. In particular, we consider random Heegaard splittings by
gluing two handlebodies by the result of a random walk in the mapping class
group of a surface. For this model of random 3-manifold, we are able to compute
the probabilities that the resulting manifolds have finite covers of particular
kinds. Our results contrast with the analogous probabilities for groups coming
from random balanced presentations, giving quantitative theorems to the effect
that 3-manifold groups have many more finite quotients than random groups. The
next natural question is whether these covers have positive betti number. For
abelian covers of a fixed type over 3-manifolds of Heegaard genus 2, we show
that the probability of positive betti number is 0.
In fact, many of these questions boil down to questions about the mapping
class group. We are lead to consider the action of mapping class group of a
surface S on the set of quotients pi_1(S) -> Q. If Q is a simple group, we show
that if the genus of S is large, then this action is very mixing. In
particular, the action factors through the alternating group of each orbit.
This is analogous to Goldman's theorem that the action of the mapping class
group on the SU(2) character variety is ergodic.Comment: 60 pages; v2: minor changes. v3: minor changes; final versio
A paradigm of open/closed duality: Liouville D-branes and the Kontsevich model
We argue that topological matrix models (matrix models of the Kontsevich
type) are examples of exact open/closed duality. The duality works at finite N
and for generic `t Hooft couplings. We consider in detail the paradigm of the
Kontsevich model for two-dimensional topological gravity. We demonstrate that
the Kontsevich model arises by topological localization of cubic open string
field theory on N stable branes. Our analysis is based on standard worldsheet
methods in the context of non-critical bosonic string theory. The stable branes
have Neumann (FZZT) boundary conditions in the Liouville direction. Several
generalizations are possible.Comment: v2: References added; a new section with generalization to non-zero
bulk cosmological constant; expanded discussion on topological localization;
added some comment
Pair Interaction Potentials of Colloids by Extrapolation of Confocal Microscopy Measurements of Collective Structure
A method for measuring the pair interaction potential between colloidal
particles by extrapolation measurement of collective structure to infinite
dilution is presented and explored using simulation and experiment. The method
is particularly well suited to systems in which the colloid is fluorescent and
refractive index matched with the solvent. The method involves characterizing
the potential of mean force between colloidal particles in suspension by
measurement of the radial distribution function using 3D direct visualization.
The potentials of mean force are extrapolated to infinite dilution to yield an
estimate of the pair interaction potential, . We use Monte Carlo (MC)
simulation to test and establish our methodology as well as to explore the
effects of polydispersity on the accuracy. We use poly-12-hydroxystearic
acid-stabilized poly(methyl methacrylate) (PHSA-PMMA) particles dispersed in
the solvent dioctyl phthalate (DOP) to test the method and assess its accuracy
for three different repulsive systems for which the range has been manipulated
by addition of electrolyte.Comment: 35 pages, 14 figure
A deep spectromorphological study of the γ -ray emission surrounding the young massive stellar cluster Westerlund 1
Context. Young massive stellar clusters are extreme environments and potentially provide the means for efficient particle acceleration. Indeed, they are increasingly considered as being responsible for a significant fraction of cosmic rays (CRs) that are accelerated within the Milky Way. Westerlund 1, the most massive known young stellar cluster in our Galaxy, is a prime candidate for studying this hypothesis. While the very-high-energy γ-ray source HESS J1646-458 has been detected in the vicinity of Westerlund 1 in the past, its association could not be firmly identified. Aims. We aim to identify the physical processes responsible for the γ-ray emission around Westerlund 1 and thus to understand the role of massive stellar clusters in the acceleration of Galactic CRs better. Methods. Using 164 h of data recorded with the High Energy Stereoscopic System (H.E.S.S.), we carried out a deep spectromorphological study of the γ-ray emission of HESS J1646-458. We furthermore employed H I and CO observations of the region to infer the presence of gas that could serve as target material for interactions of accelerated CRs. Results. We detected large-scale (~2 diameter) γ-ray emission with a complex morphology, exhibiting a shell-like structure and showing no significant variation with γ-ray energy. The combined energy spectrum of the emission extends to several tens of TeV, and it is uniform across the entire source region. We did not find a clear correlation of the γ-ray emission with gas clouds as identified through H I and CO observations. Conclusions. We conclude that, of the known objects within the region, only Westerlund 1 can explain the majority of the γ-ray emission. Several CR acceleration sites and mechanisms are conceivable and discussed in detail. While it seems clear that Westerlund 1 acts as a powerful particle accelerator, no firm conclusions on the contribution of massive stellar clusters to the flux of Galactic CRs in general can be drawn at this point
Neurodevelopmental toxicity of prenatal polychlorinated biphenyls (PCBs) by chemical structure and activity: a birth cohort study
Abstract Background Polychlorinated biphenyls (PCBs) are ubiquitous environmental toxins. Although there is growing evidence to support an association between PCBs and deficits of neurodevelopment, the specific mechanisms are not well understood. The potentially different roles of specific PCB groups defined by chemical structures or hormonal activities e.g., dioxin-like, non-dioxin like, or anti-estrogenic PCBs, remain unclear. Our objective was to examine the association between prenatal exposure to defined subsets of PCBs and neurodevelopment in a cohort of infants in eastern Slovakia enrolled at birth in 2002-2004. Methods Maternal and cord serum samples were collected at delivery, and analyzed for PCBs using high-resolution gas chromatography. The Bayley Scales of Infant Development -II (BSID) were administered at 16 months of age to over 750 children who also had prenatal PCB measurements. Results Based on final multivariate-adjusted linear regression model, maternal mono-ortho-substituted PCBs were significantly associated with lower scores on both the psychomotor (PDI) and mental development indices (MDI). Also a significant association between cord mono-ortho-substituted PCBs and reduced PDI was observed, but the association with MDI was marginal (p = 0.05). Anti-estrogenic and di-ortho-substituted PCBs did not show any statistically significant association with cognitive scores, but a suggestive association between di-ortho-substituted PCBs measured in cord serum and poorer PDI was observed. Conclusion Children with higher prenatal mono-ortho-substituted PCB exposures performed more poorly on the Bayley Scales. Evidence from this and other studies suggests that prenatal dioxin-like PCB exposure, including mono-ortho congeners, may interfere with brain development in utero. Non-dioxin-like di-ortho-substituted PCBs require further investigation
Effects of correctional boot camps on offending
Background: Correctional boot camps were first opened in United States
adult correctional systems in 1983. Since that time they have rapidly grown,
first within adult systems and later in juvenile corrections, primarily within the
United States. In the typical boot camp, participants are required to follow a
rigorous daily schedule of activities including drill and ceremony and physical
training, similar to that of a military boot-camp. Punishment for misbehavior
is immediate and swift and usually involves some type of physical activity
like push-ups. Boot-camps differ substantially in the amount of focus given to
the physical training and hard labor aspects of the program versus therapeutic
programming such as academic education, drug treatment or cognitive skills.
Objectives: To synthesize the extant empirical evidence on the effects of
boot-camps and boot camp like programs on the criminal behavior (e.g., postrelease
arrest, conviction, or reinstitutionalization) of convicted adult and juvenile
offenders.
Search Strategy: Numerous electronic databases were searched for both
published an unpublished studies. The keywords used were: boot camp(s),
intensive incarceration, and shock incarceration. We also contacted U.S and
non-U.S. researchers working in this area requesting assistance in locating
additional studies. The final search of these sources was completed in early
December of 2003.
Selection Criteria: The eligibility criteria were (a) that the study evaluated
a correctional boot camp, shock incarceration, or intensive incarceration
program; (b) that the study included a comparison group that received either
probation or incarceration in an alternative facility; (c) that the study participants
were exclusively under the supervision of the criminal or juvenile justice
system; and (d) that the study reported a post-program measure of criminal behavior,
such as arrest or conviction.
Data Collection and Analysis: The coding protocol captured aspects of
the research design, including methodological quality, the boot-camp program,
the comparison group condition, the participant offenders, the outcome
measures and the direction and magnitude of the observed effects. All studies
were coded by two independent coders and all coding differences were resolved
by Drs. MacKenzie or Wilson. Outcome effects were coded using the
odds-ratio and meta-analysis was performed using the random effects model.
Main Results: Thirty-two unique research studies met our inclusion criteria.
These studies reported the results from 43 independent boot-camp/comparison
samples. The random effects mean odds-ratio for any form of recidivism was
1.02, indicating that the likelihood that boot camp participants recidivating was roughly equal to the likelihood of comparison participants recidivating.
This overall finding was robust to the selection of the outcome measure and
length of follow-up. Methodological features were only weakly related to outcome
among these studies and did not explain the null findings. The overall
effect for juvenile boot camps was slightly lower than for adult boot camps.
Moderator analysis showed that studies evaluating boot-camp programs with
a strong treatment focus had a larger mean odds-ratio than studies evaluating
boot camps with a weak treatment focus.
Conclusions: Although the overall effect appears to be that of “no difference,”
some studies found that boot camp participants did better than the
comparison, while others found that comparison samples did better. However,
all of these studies had the common element of a militaristic boot camp
program for offenders. The current evidence suggests that this common and
defining feature of a boot-camp is not effective in reducing post boot-camp
offending
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