860 research outputs found
On CSP and the Algebraic Theory of Effects
We consider CSP from the point of view of the algebraic theory of effects,
which classifies operations as effect constructors or effect deconstructors; it
also provides a link with functional programming, being a refinement of Moggi's
seminal monadic point of view. There is a natural algebraic theory of the
constructors whose free algebra functor is Moggi's monad; we illustrate this by
characterising free and initial algebras in terms of two versions of the stable
failures model of CSP, one more general than the other. Deconstructors are
dealt with as homomorphisms to (possibly non-free) algebras.
One can view CSP's action and choice operators as constructors and the rest,
such as concealment and concurrency, as deconstructors. Carrying this programme
out results in taking deterministic external choice as constructor rather than
general external choice. However, binary deconstructors, such as the CSP
concurrency operator, provide unresolved difficulties. We conclude by
presenting a combination of CSP with Moggi's computational {\lambda}-calculus,
in which the operators, including concurrency, are polymorphic. While the paper
mainly concerns CSP, it ought to be possible to carry over similar ideas to
other process calculi
Debris Disks: Probing Planet Formation
Debris disks are the dust disks found around ~20% of nearby main sequence
stars in far-IR surveys. They can be considered as descendants of
protoplanetary disks or components of planetary systems, providing valuable
information on circumstellar disk evolution and the outcome of planet
formation. The debris disk population can be explained by the steady
collisional erosion of planetesimal belts; population models constrain where
(10-100au) and in what quantity (>1Mearth) planetesimals (>10km in size)
typically form in protoplanetary disks. Gas is now seen long into the debris
disk phase. Some of this is secondary implying planetesimals have a Solar
System comet-like composition, but some systems may retain primordial gas.
Ongoing planet formation processes are invoked for some debris disks, such as
the continued growth of dwarf planets in an unstirred disk, or the growth of
terrestrial planets through giant impacts. Planets imprint structure on debris
disks in many ways; images of gaps, clumps, warps, eccentricities and other
disk asymmetries, are readily explained by planets at >>5au. Hot dust in the
region planets are commonly found (<5au) is seen for a growing number of stars.
This dust usually originates in an outer belt (e.g., from exocomets), although
an asteroid belt or recent collision is sometimes inferred.Comment: Invited review, accepted for publication in the 'Handbook of
Exoplanets', eds. H.J. Deeg and J.A. Belmonte, Springer (2018
Evaluation of focal hepatic masses: a comparative study of MRI and CT
We evaluated suspected hepatic lesions in 30 patients using both nongated spin-echo magnetic resonance imaging (MRI) on a 0.35 T superconducting magnet and contrast-enhanced dynamic incremental computed tomography (CT). In the 27 patients with focal lesions, both modalities detected abnormalities in 26 patients. Liver lesions were equally well demonstrated using MRI and CT in 15 patients, better demonstrated by CT in 11 patients, and better demonstrated by MRI in 1 patient. Small lesions (<2 cm) were much better demonstrated using CT than MRI; this was significant when knowledge of the precise extent of disease was necessary for planning surgical therapy or for evaluating response to chemotherapy. Five patients had significant extrahepatic disease detected by CT; MRI identified extrahepatic abnormalities in only 2 of these 5 patients. We conclude that at the current time CT is more useful than nongated spin-echo MRI in the evaluation of suspected hepatic masses.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/48127/1/261_2005_Article_BF02035086.pd
Entrepreneurial sons, patriarchy and the Colonels' experiment in Thessaly, rural Greece
Existing studies within the field of institutional entrepreneurship explore how entrepreneurs influence change in economic institutions. This paper turns the attention of scholarly inquiry on the antecedents of deinstitutionalization and more specifically, the influence of entrepreneurship in shaping social institutions such as patriarchy. The paper draws from the findings of ethnographic work in two Greek lowland village communities during the military Dictatorship (1967–1974). Paradoxically this era associated with the spread of mechanization, cheap credit, revaluation of labour and clear means-ends relations, signalled entrepreneurial sons’ individuated dissent and activism who were now able to question the Patriarch’s authority, recognize opportunities and act as unintentional agents of deinstitutionalization. A ‘different’ model of institutional change is presented here, where politics intersects with entrepreneurs, in changing social institutions. This model discusses the external drivers of institutional atrophy and how handling dissensus (and its varieties over historical time) is instrumental in enabling institutional entrepreneurship
Composite structural motifs of binding sites for delineating biological functions of proteins
Most biological processes are described as a series of interactions between
proteins and other molecules, and interactions are in turn described in terms
of atomic structures. To annotate protein functions as sets of interaction
states at atomic resolution, and thereby to better understand the relation
between protein interactions and biological functions, we conducted exhaustive
all-against-all atomic structure comparisons of all known binding sites for
ligands including small molecules, proteins and nucleic acids, and identified
recurring elementary motifs. By integrating the elementary motifs associated
with each subunit, we defined composite motifs which represent
context-dependent combinations of elementary motifs. It is demonstrated that
function similarity can be better inferred from composite motif similarity
compared to the similarity of protein sequences or of individual binding sites.
By integrating the composite motifs associated with each protein function, we
define meta-composite motifs each of which is regarded as a time-independent
diagrammatic representation of a biological process. It is shown that
meta-composite motifs provide richer annotations of biological processes than
sequence clusters. The present results serve as a basis for bridging atomic
structures to higher-order biological phenomena by classification and
integration of binding site structures.Comment: 34 pages, 7 figure
Three dysregulated miRNAs control kallikrein 10 expression and cell proliferation in ovarian cancer
Dusty Planetary Systems
Extensive photometric stellar surveys show that many main sequence stars show
emission at infrared and longer wavelengths that is in excess of the stellar
photosphere; this emission is thought to arise from circumstellar dust. The
presence of dust disks is confirmed by spatially resolved imaging at infrared
to millimeter wavelengths (tracing the dust thermal emission), and at optical
to near infrared wavelengths (tracing the dust scattered light). Because the
expected lifetime of these dust particles is much shorter than the age of the
stars (>10 Myr), it is inferred that this solid material not primordial, i.e.
the remaining from the placental cloud of gas and dust where the star was born,
but instead is replenished by dust-producing planetesimals. These planetesimals
are analogous to the asteroids, comets and Kuiper Belt objects (KBOs) in our
Solar system that produce the interplanetary dust that gives rise to the
zodiacal light (tracing the inner component of the Solar system debris disk).
The presence of these "debris disks" around stars with a wide range of masses,
luminosities, and metallicities, with and without binary companions, is
evidence that planetesimal formation is a robust process that can take place
under a wide range of conditions. This chapter is divided in two parts. Part I
discusses how the study of the Solar system debris disk and the study of debris
disks around other stars can help us learn about the formation, evolution and
diversity of planetary systems by shedding light on the frequency and timing of
planetesimal formation, the location and physical properties of the
planetesimals, the presence of long-period planets, and the dynamical and
collisional evolution of the system. Part II reviews the physical processes
that affect dust particles in the gas-free environment of a debris disk and
their effect on the dust particle size and spatial distribution.Comment: 68 pages, 25 figures. To be published in "Solar and Planetary
Systems" (P. Kalas and L. French, Eds.), Volume 3 of the series "Planets,
Stars and Stellar Systems" (T.D. Oswalt, Editor-in-chief), Springer 201
Perception of epidemic's related anxiety in the General French Population: a cross-sectional study in the Rhône-Alpes region
International audienceBackgroundTo efficiently plan appropriate public health interventions during possible epidemics, governments must take into consideration the following factors about the general population: their knowledge of epidemics, their fears of and psychological responses to them, their level of compliance with government measures and their communities' trusted sources of information. However, such surveys among the French general population are rare.MethodsA cross-sectional study was conducted in 2006 in a representative sample of 600 subjects living in the Rhône-Alpes region (south-east France) to investigate self-reported knowledge about infectious diseases and anxiety generated by epidemic risk with particular reference to avian influenza. Data on reactions to potentially new epidemics and the confidence level in various sources of information were also collected.ResultsRespondents were most knowledgeable about AIDS, followed by avian influenza. Overall, 75% of respondents had adequate knowledge of avian influenza. The percentage was even higher (88%) among inhabitants of the Ain district, where an avian influenza epidemic had previously been reported. However, 39% expressed anxiety about this disease. In total, 20% of respondents with knowledge about avian influenza stated that they had changed their behaviours during the epizooty. Epidemics were perceived as a real threat by 27% of respondents. In the event of a highly contagious outbreak, the majority of respondents said they would follow the advice given by authorities. The study population expressed a high level of confidence in physicians and scientists, but had strong reservations about politicians, deputies and the media.ConclusionsAlthough the survey was conducted only four months after the avian influenza outbreak, epidemics were not perceived as a major threat by the study population. The results showed that in the event of a highly infectious disease, the population would comply with advice given by public authorities
Sensitization of interferon-γ induced apoptosis in human osteosarcoma cells by extracellular S100A4
BACKGROUND: S100A4 is a small Ca(2+)-binding protein of the S100 family with metastasis-promoting properties. Recently, secreted S100A4 protein has been shown to possess a number of functions, including induction of angiogenesis, stimulation of cell motility and neurite extension. METHODS: Cell cultures from two human osteosarcoma cell lines, OHS and its anti-S100A4 ribozyme transfected counterpart II-11b, was treated with IFN-γ and recombinant S100A4 in order to study the sensitizing effects of extracellular S100A4 on IFN-γ mediated apoptosis. Induction of apoptosis was demonstrated by DNA fragmentation, cleavage of poly (ADP-ribose) polymerase and Lamin B. RESULTS: In the present work, we found that the S100A4-expressing human osteosarcoma cell line OHS was more sensitive to IFN-γ-mediated apoptosis than the II-11b cells. S100A4 protein was detected in conditioned medium from OHS cells, but not from II-11b cells, and addition of recombinant S100A4 to the cell medium sensitized II-11b cells to apoptosis induced by IFN-γ. The S100A4/IFN-γ-mediated induction of apoptosis was shown to be independent of caspase activation, but dependent on the formation of reactive oxygen species. Furthermore, addition of extracellular S100A4 was demonstrated to activate nuclear factor-κB (NF-κB). CONCLUSION: In conclusion, we have shown that S100A4 sensitizes osteosarcoma cells to IFN-γ-mediated induction of apoptosis. Additionally, extracellular S100A4 activates NF-κB, but whether these events are causally related remains unknown
Pattern of injury mortality by age-group in children aged 0–14 years in Scotland, 2002–2006, and its implications for prevention
<p>Abstract</p> <p>Background</p> <p>Knowledge of the epidemiology of injuries in children is essential for the planning, implementation and evaluation of preventive measures but recent epidemiological information on injuries in children both in general and by age-group in Scotland is scarce. This study examines the recent pattern of childhood mortality from injury by age-group in Scotland and considers its implications for prevention.</p> <p>Methods</p> <p>Routine mortality data for the period 2002–2006 were obtained from the General Register Office for Scotland and were analysed in terms of number of deaths, mean annual mortality rates per 100,000 population, leading causes of death, and causes of injury death. Mid-year population estimates were used as the denominator. Chi-square tests were used to determine statistical significance.</p> <p>Results</p> <p>186 children aged 0–14 died from an injury in Scotland during 2002–06 (MR 4.3 per 100,000). Injuries were the leading cause of death in 1–14, 5–9 and 10–14 year-olds (causing 25%, 29% and 32% of all deaths respectively). The leading individual causes of injury death (0–14 years) were pedestrian and non-pedestrian road-traffic injuries and assault/homicide but there was variation by age-group. Assault/homicide, fire and suffocation caused most injury deaths in young children; road-traffic injuries in older ones. Collectively, intentional injuries were a bigger threat to the lives of under-15s than any single cause of unintentional injury. The mortality rate from assault/homicide was highest in infants (<1 year) and decreased with increasing age. Children aged 5–9 were significantly less likely to die from an injury than 0–4 or 10–14 year-olds (p < 0.05). Suicide was an important cause of injury mortality in 10–14 year-olds.</p> <p>Conclusion</p> <p>Injuries continue to be a leading cause of death in childhood in Scotland. Variation in causes of injury death by age-group is important when targeting preventive efforts. In particular, the threats of assault/homicide in infants, fire in 1–4 year-olds, pedestrian injury in 5–14 year-olds, and suicide in 10–14 year-olds need urgent consideration for preventive action.</p
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