24,691 research outputs found
Time evolution of the Partridge-Barton Model
The time evolution of the Partridge-Barton model in the presence of the
pleiotropic constraint and deleterious somatic mutations is exactly solved for
arbitrary fecundity in the context of a matricial formalism. Analytical
expressions for the time dependence of the mean survival probabilities are
derived. Using the fact that the asymptotic behavior for large time is
controlled by the largest matrix eigenvalue, we obtain the steady state values
for the mean survival probabilities and the Malthusian growth exponent. The
mean age of the population exhibits a power law decayment. Some Monte
Carlo simulations were also performed and they corroborated our theoretical
results.Comment: 10 pages, Latex, 1 postscript figure, published in Phys. Rev. E 61,
5664 (2000
Consequences of wall stiffness for a beta-soft potential
Modifications of the infinite square well E(5) and X(5) descriptions of
transitional nuclear structure are considered. The eigenproblem for a potential
with linear sloped walls is solved. The consequences of the introduction of
sloped walls and of a quadratic transition operator are investigated.Comment: RevTeX 4, 8 pages, as published in Phys. Rev.
âThe show must go on!â Fieldwork, mental health and wellbeing in Geography, Earth and Environmental Sciences
Fieldwork is central to the identity, culture and history of academic Geography, Earth and Environmental Sciences (GEES). However, in this paper we recognise that, for many academic staff, fieldtrips can be a profoundly challenging âordeal,â illâconducive to wellness or effective pedagogic practice. Drawing on research with 39 UK universityâbased GEES academics who selfâidentify as having a mental health condition, we explore how mental health intersects with spaces and expectations of fieldwork in Higher Education. We particularly focus on their accounts of undertaking undergraduate residential fieldtrips and give voice to these largely undisclosed experiences. Their narratives run counter to normative, romanticised celebrations of fieldwork within GEES disciplines. We particularly highlight recurrent experiences of avoiding fieldwork, fieldworkâasâ ordeal, and âcopingâ with fieldwork, and suggest that commonplace anxieties within the neoliberal academy â about performance, productivity, fitnessâtoâwork, selfâpresentation, scrutiny and fearâofâfallingâbehind â are felt particularly intensely during fieldwork. In spite of considerable work to make fieldwork more accessible to students, we find that fieldâbased teaching is experienced as a focal site of distress, anxiety and ordeal for many GEES academics with common mental health conditions. We conclude with prompts for reflection about how fieldwork could be otherwise
Rotational Correlation Functions of Single Molecules
Single molecule rotational correlation functions are analyzed for several
reorientation geometries. Even for the simplest model of isotropic rotational
diffusion our findings predict non-exponential correlation functions to be
observed by polarization sensitive single molecule fluorescence microscopy.
This may have a deep impact on interpreting the results of molecular
reorientation measurements in heterogeneous environments.Comment: 5 pages, 4 figure
Probing the Weak Boson Sector in
We study possible deviations from the standard model in the reaction at a 500 GeV collider. As a photon source we use a
laser backscattered photon beam. We investigate the most general and vertices including operators up to
energy-dimension-six which are Lorentz invariant. These vertices require four
extra parameters; two are CP-conserving, and , and two are
CP-violating, and . We present analytical expressions of
the helicity amplitudes for the process for arbitrary
values of anomalous couplings. Assuming Standard Model values are actually
measured we present the allowed region in the () plane at the
90\% confidence level. We then show how the angular correlation of the
decay products can be used to extract detailed information on the anomalous
(especially CP-violating) and couplings.Comment: Latex, 25 pages, 12 figures (not included). One compressed postscript
file including all the figures available at
ftp://ftp.kek.jp/kek/preprints/TH/TH-420/kekth420.ps.g
Strain field in straight cylindrical shells due to applied forces on an attached shell. Part I: No hole in the intersection region
The results of an experimental stress analysis of the intersection region of two straight cylindrical shells are presented. Two models were used; in the first model the two axes were inclined at 30 degrees while for the second case, this angle was 60 degrees. In each case, the main shell was 6.625 in. in diameter and 0.198 in. thick, while the attached shell was 3.5 in. in diameter and 0.226 in. thick. The intersection region was subjected to in-plane and out-plane moments applied to the attached shell and the measurements were made using foil resistance rosette gauges. These measurements demonstrate that the local stress concentration in the intersection region of the main shell increases with the increase of the acute angle between the axes of the two shells; thus for a given moment loading on the attached shell, the stress concentration will be the largest when the two axes are normal to each other.Yeshttps://us.sagepub.com/en-us/nam/manuscript-submission-guideline
Euclidean Distances, soft and spectral Clustering on Weighted Graphs
We define a class of Euclidean distances on weighted graphs, enabling to
perform thermodynamic soft graph clustering. The class can be constructed form
the "raw coordinates" encountered in spectral clustering, and can be extended
by means of higher-dimensional embeddings (Schoenberg transformations).
Geographical flow data, properly conditioned, illustrate the procedure as well
as visualization aspects.Comment: accepted for presentation (and further publication) at the ECML PKDD
2010 conferenc
Risk factors for recurrence in patients with Clostridium difficile infection due to 027 and non-027 ribotypes
Objectives: Our objective was to evaluate factors associated with recurrence in patients with 027+ and 027â Clostridium difficile infection (CDI). Methods: Patients with CDI observed between January and December 2014 in six hospitals were consecutively included in the study. The 027 ribotype was deduced by the presence of tcdB, tcdB, cdt genes and the deletion Î117 in tcdC (XpertÂź C. difficile/Epi). Recurrence was defined as a positive laboratory test result for C. difficile more than 14 days but within 8 weeks after the initial diagnosis date with reappearance of symptoms. To identify factors associated with recurrence in 027+ and 027â CDI, a multivariate analysis was performed in each patient group. Subdistributional hazard ratios (sHRs) and 95% confidence intervals (95%CIs) were calculated. Results: Overall, 238 patients with 027+ CDI and 267 with 027â CDI were analysed. On multivariate analysis metronidazole monotherapy (sHR 2.380, 95%CI 1.549â3.60, p <0.001) and immunosuppressive treatment (sHR 3.116, 95%CI 1.906â5.090, p <0.001) were factors associated with recurrence in patients with 027+ CDI. In this patient group, metronidazole monotherapy was independently associated with recurrence in both mild/moderate (sHR 1.894, 95%CI 1.051â3.410, p 0.033) and severe CDI (sHR 2.476, 95%CI 1.281â4.790, p 0.007). Conversely, non-severe disease (sHR 3.704, 95%CI 1.437â9.524, p 0.007) and absence of chronic renal failure (sHR 16.129, 95%CI 2.155â125.000, p 0.007) were associated with recurrence in 027â CDI. Conclusions: Compared to vancomycin, metronidazole monotherapy appears less effective in curing CDI without relapse in the 027+ patient group, independently of disease severity
IP6K3 and IPMK variations in LOAD and longevity: evidence for a multifaceted signaling network at the crossroad between neurodegeneration and survival
Several studies reported that genetic variants predisposing to neurodegeneration were at higher frequencies in centenarians than in younger controls, suggesting they might favor also longevity.
IP6K3 and IPMK regulate many crucial biological functions by mediating synthesis of inositol poly- and pyrophosphates and by acting non-enzymatically via proteinâprotein interactions. Our previous studies suggested they affect Late Onset Alzheimer Disease (LOAD) and longevity, respectively. Here, in the same sample groups, we investigated whether variants of IP6K3 also affect longevity, and variants of IPMK also influence LOAD susceptibility. We found that: i) a SNP of IP6K3 previously associated with increased risk of LOAD increased the chance to become long-lived, ii) SNPs of IPMK, previously associated with decreased longevity, were protective factors for LOAD, as previously observed for UCP4. SNP-SNP interaction analysis, including our previous data, highlighted phenotype-specific interactions between sets of alleles. Moreover, linkage disequilibrium and eQTL data associated to analyzed variants suggested mitochondria as crossroad of interconnected pathways crucial for susceptibility to neurodegeneration and/or longevity.
Overall, data support the view that in these traits interactions may be more important than single polymorphisms. This phenomenon may contribute to the non-additive heritability of neurodegeneration and longevity and be part of the missing heritability of these traits
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