6,211 research outputs found
Effect of selection on ancestry: an exactly soluble case and its phenomenological generalization
We consider a family of models describing the evolution under selection of a
population whose dynamics can be related to the propagation of noisy traveling
waves. For one particular model, that we shall call the exponential model, the
properties of the traveling wave front can be calculated exactly, as well as
the statistics of the genealogy of the population. One striking result is that,
for this particular model, the genealogical trees have the same statistics as
the trees of replicas in the Parisi mean-field theory of spin glasses. We also
find that in the exponential model, the coalescence times along these trees
grow like the logarithm of the population size. A phenomenological picture of
the propagation of wave fronts that we introduced in a previous work, as well
as our numerical data, suggest that these statistics remain valid for a larger
class of models, while the coalescence times grow like the cube of the
logarithm of the population size.Comment: 26 page
Random walks of partons in SU(N_c) and classical representations of color charges in QCD at small x
The effective action for wee partons in large nuclei includes a sum over
static color sources distributed in a wide range of representations of the
SU(N_c) color group. The problem can be formulated as a random walk of partons
in the N_c-1 dimensional space spanned by the Casimirs of SU(N_c). For a large
number of sources, k >> 1, we show explicitly that the most likely
representation is a classical representation of order O(\sqrt{k}). The quantum
sum over representations is well approximated by a path integral over classical
sources with an exponential weight whose argument is the quadratic Casimir
operator of the group. The contributions of the higher N_c-2 Casimir operators
are suppressed by powers of k. Other applications of the techniques developed
here are discussed briefly.Comment: 51 pages, includes 3 eps file
The perception and management of risk in UK office property development
Risk is an ever-present aspect of business, and risk taking is necessary for profit and economic progress. Speculative property development is popularly perceived as a 'risky business' yet, like other entrepreneurs, developers have opportunities to manage the risks they face; techniques include phasing and joint ventures. The associated areas of investment portfolio risk, development risk analysis and construction risk management have all been addressed by research. This article presents new knowledge about how developers perceive risks and the means they subsequently adopt to manage them. The developers of office projects across the UK were sent questionnaires by post. Respondents were asked about their perceptions of risks at the first appraisal stage and currently and about the risk management techniques that they had adopted. In-depth interviews with a selection of respondents were then used to discuss and augment the findings. Developers were most concerned about market-based risks at both stages. Concern about production-orientated risks was lower and fell significantly between the two stages. A fixed price contract was the most common risk management technique. Risk management techniques were used more often outside London and the South East. Developer type affects both the perception and management of risk. While developers do manage risk, decisions are made on the basis of professional and business experience. These findings should help development companies manage risk in a more objective and analytical way
Principles and Operational Parameters to Optimize Poison Removal with Extracorporeal Treatments
A role for nephrologists in the management of a poisoned patient involves evaluating the indications for, and methods of, enhancing the elimination of a poison. Nephrologists are familiar with the various extracorporeal treatments ( ECTR s) used in the management of impaired kidney function, and their respective advantages and disadvantages. However, these same skills and knowledge may not always be considered, or applicable, when prescribing ECTR for the treatment of a poisoned patient. Maximizing solute elimination is a key aim of such treatments, perhaps more so than in the treatment of uremia, because ECTR has the potential to reverse clinical toxicity and shorten the duration of poisoning. This manuscript reviews the various principles that govern poison elimination by ECTR (diffusion, convection, adsorption, and centrifugation) and how components of the ECTR can be adjusted to maximize clearance. Data supporting these recommendations will be presented, whenever available.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/108055/1/sdi12247.pd
Nonadjacent dependency processing in monkeys, apes and humans
The ability to track syntactic relationships between words, particularly over distances (“nonadjacent dependencies”), is a critical faculty underpinning human language, although its evolutionary origins remain poorly understood. While some monkey species are reported to process auditory nonadjacent dependencies, comparative data from apes are missing, complicating inferences regarding shared ancestry. Here, we examined nonadjacent dependency processing in common marmosets, chimpanzees, and humans using “artificial grammars”: strings of arbitrary acoustic stimuli composed of adjacent (nonhumans) or nonadjacent (all species) dependencies. Individuals from each species (i) generalized the grammars to novel stimuli and (ii) detected grammatical violations, indicating that they processed the dependencies between constituent elements. Furthermore, there was no difference between marmosets and chimpanzees in their sensitivity to nonadjacent dependencies. These notable similarities between monkeys, apes, and humans indicate that nonadjacent dependency processing, a crucial cognitive facilitator of language, is an ancestral trait that evolved at least ~40 million years before language itself
EGFR inhibitors erlotinib and lapatinib ameliorate epidermal blistering in pemphigus vulgaris in a non-linear, V-shaped relationship
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Mental health assessments in refugees and asylum seekers
Background Mental health problems resulting from persecution and forced
migration are very common among refugees and asylum seekers and evolve into a
major public health challenge in hosting societies. Language barriers often
prevent timely access to appropriate health care, leading to chronic
trajectories and abortive social integration. Tools for multilingual screening
and assessment could be of great benefit for this particularly vulnerable
population as well as for policy makers. This study aimed at testing the
reliability, feasibility and usability of the Multi-Adaptive Psychological
Screening Software (MAPSS), a newly developed Audio Computer-Assisted Self-
Interview Software (ACASI) for touchscreen devices, for screening purposes in
a clinical setting. Methods In a randomized cross-over design including both
MAPSS and paper-pencil clinician-administered interviews, 30 treatment-seeking
refugees completed clinical measures and a feasibility questionnaire to rate
the user interface of MAPSS. Five professionals performed given tasks in MAPSS
and completed usability questionnaires for the administration interface.
Results Results showed no differences between the two assessment modalities
with regard to symptom scores. The findings suggest good feasibility and
usability of MAPSS in traumatized refugees. The administration via MAPSS was
significantly shorter than the paper-pencil interview. Conclusion MAPSS may be
a cost-effective, flexible and valid alternative to interpreter-based
psychometric screening and assessment
An Infrared through Radio Study of the Properties and Evolution of IRDC Clumps
We examine the physical properties and evolutionary stages of a sample of 17
clumps within 8 Infrared Dark Clouds (IRDCs) by combining existing infrared,
millimeter, and radio data with new Bolocam Galactic Plane Survey (BGPS) 1.1 mm
data, VLA radio continuum data, and HHT dense gas (HCO+ and N2H+) spectroscopic
data. We combine literature studies of star formation tracers and dust
temperatures within IRDCs with our search for ultra-compact (UC) HII regions to
discuss a possible evolutionary sequence for IRDC clumps. In addition, we
perform an analysis of mass tracers in IRDCs and find that 8 micron extinction
masses and 1.1 mm Bolocam Galactic Plane Survey (BGPS) masses are complementary
mass tracers in IRDCs except for the most active clumps (notably those
containing UCHII regions), for which both mass tracers suffer biases. We find
that the measured virial masses in IRDC clumps are uniformly higher than the
measured dust continuum masses on the scale of ~1 pc. We use 13CO, HCO+, and
N2H+ to study the molecular gas properties of IRDCs and do not see any evidence
of chemical differentiation between hot and cold clumps on the scale of ~1 pc.
However, both HCO+ and N2H+ are brighter in active clumps, due to an increase
in temperature and/or density. We report the identification of four UCHII
regions embedded within IRDC clumps and find that UCHII regions are associated
with bright (>1 Jy) 24 micron point sources, and that the brightest UCHII
regions are associated with "diffuse red clumps" (an extended enhancement at 8
micron). The broad stages of the discussed evolutionary sequence (from a
quiescent clump to an embedded HII region) are supported by literature dust
temperature estimates; however, no sequential nature can be inferred between
the individual star formation tracers.Comment: 33 pages, 26 figures, 6 tables, accepted for publication in ApJ. Full
resolution version available here:
http://casa.colorado.edu/~battersb/Publications.htm
The Dipole Picture and Saturation in Soft Processes
We attempt to describe soft hadron interactions in the framework of
saturation models, one based upon the Balitsky-Kovchegov non-linear equation
and another one due to Golec-Biernat and W\"{u}sthoff. For , , and scattering the relevant hadronic wave functions are formulated, and total,
elastic cross-sections, and the forward elastic slope are calculated and
compared to experimental data. The saturation mechanism leads to reasonable
reproduction of the data for the quantities analyzed, except for the forward
elastic slope, where the predicted increase with energy is too moderate.Comment: 12 pages, 4 figures. One figure and several explanations are added.
The version is to appear in PL
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