239 research outputs found
Jamming, relaxation and crystallization of a super-cooled fluid in a three-dimensional lattice
Off-equilibrium dynamics of a three-dimensional lattice model with nearest-
and next nearest-neighbors exclusions is studied. At equilibrium, the model
undergoes a first-order fluid-solid transition. Non-equilibrium filling,
through random sequential adsorption with diffusion, creates amorphous
structures and terminates at a disordered state with random closest packing
density that lies in the equilibrium solid regime. The approach towards random
closest packing is characterized by two distinct power-law regimes, reflecting
the formation of small densely packed grains in the long time regime of the
filling process. We then study the fixed-density relaxation of these amorphous
structures towards the solid phase. The route to crystallization is shown to
deviate from the simple grain growth proposed by classical nucleation theory.
Our measurements suggest that relaxation is driven mainly by coalescence of
neighboring crystallized grains which exist in the initial amorphous state
A finite-temperature liquid-quasicrystal transition in a lattice model
We consider a tiling model of the two-dimensional square-lattice, where each
site is tiled with one of the sixteen Wang tiles. The ground states of this
model are all quasi-periodic. The systems undergoes a disorder to
quasi-periodicity phase transition at finite temperature. Introducing a proper
order-parameter, we study the system at criticality, and extract the critical
exponents characterizing the transition. The exponents obtained are consistent
with hyper-scaling
Constructing Fluorogenic Bacillus Spores (F-Spores) via Hydrophobic Decoration of Coat Proteins
Background: Bacterial spores are protected by a coat consisting of about 60 different proteins assembled as a biochemically complex structure with intriguing morphological and mechanical properties. Historically, the coat has been considered a static structure providing rigidity and mainly acting as a sieve to exclude exogenous large toxic molecules, such as lytic enzymes. Over recent years, however, new information about the coat’s architecture and function have emerged from experiments using innovative tools such as automated scanning microscopy, and high resolution atomic force microscopy. Principal Findings: Using thin-section electron microscopy, we found that the coat of Bacillus spores has topologically specific proteins forming a layer that is identifiable because it spontaneously becomes decorated with hydrophobic fluorogenic probes from the milieu. Moreover, spores with decorated coat proteins (termed F-spores) have the unexpected attribute of responding to external germination signals by generating intense fluorescence. Fluorescence data from diverse experimental designs, including F-spores constructed from five different Bacilli species, indicated that the fluorogenic ability of F-spores is under control of a putative germination-dependent mechanism. Conclusions: This work uncovers a novel attribute of spore-coat proteins that we exploited to decorate a specific layer imparting germination-dependent fluorogenicity to F-spores. We expect that F-spores will provide a model system to gai
Comparison of HTK-Custodiol and St-Thomas solution as cardiac preservation solutions on early and midterm outcomes following heart transplantation.
The choice of the cardiac preservation solution for myocardial protection at time of heart procurement remains controversial and uncertainties persist regarding its effect on the early and midterm heart transplantation (HTx) outcomes. We retrospectively compared our adult HTx performed with 2 different solutions, in terms of hospital mortality, mid-term survival, inotropic score, primary graft dysfunction and rejection score.
From January 2009 to December 2020, 154 consecutive HTx of adult patients, followed up in pre- and post-transplantation by 2 different tertiary centres, were performed at the University Hospital of Lausanne, Switzerland. From 2009 to 2015, the cardiac preservation solution used was exclusively St-Thomas, whereafter an institutional decision was made to use HTK-Custodiol only. Patients were classified in 2 groups accordingly.
There were 75 patients in the St-Thomas group and 79 patients in the HTK-Custodiol group. The 2 groups were comparable in terms of preoperative and intraoperative characteristics. Postoperatively, compared to the St-Thomas group, the Custodiol group patients showed significantly lower inotropic scores [median (interquartile range): 35.7 (17.5-60.2) vs 71.8 (31.8-127), P < 0.001], rejection scores [0.08 (0.0-0.25) vs 0.14 (0.05-0.5), P = 0.036] and 30-day mortality rate (2.5% vs 14.7%, P = 0.007) even after adjusting for potential confounders. Microscopic analysis of the endomyocardial biopsies also showed less specific histological features of subendothelial ischaemia (3.8% vs 17.3%, P = 0.006). There was no difference in primary graft dysfunction requiring postoperative extracorporeal membrane oxygenation. The use of HTK-Custodiol solution significantly improved midterm survival (Custodiol versus St-Thomas: hazard ratio = 0.20, 95% confidence interval: 0.069-0.60, P = 0.004).
This retrospective study comparing St-Thomas solution and HTK-Custodiol as myocardial protection during heart procurement showed that Custodiol improves outcomes after HTx, including postoperative inotropic score, rejection score, 30-day mortality and midterm survival
The Grizzly, April 24, 2014
Ursinus Conducts First Ever ISGP Conference on Pandemic Preparedness • Library Staff Planning for Big Changes • First Schellhase Ursinus Essay Prize Announced on CoSa Day • Annual Charity Art Fair to Support Camp Cranium • Political Activists to Speak at Graduation • Senior Fellows Help to Shape the Incoming Freshman Class • Alumni Weekend to be Held on Campus • Opinion: Parents Influence our Political Beliefs; Fight to Preserve Net Neutrality in the US • Balancing Act for the Ages: Senior Bryn O\u27Neill • Opinion: MLB Must Move on From Steroid Era • Men\u27s Lacrosse Stays Alive, Baseball Splits with JHUhttps://digitalcommons.ursinus.edu/grizzlynews/1905/thumbnail.jp
Ataxia-telangiectasia: Linkage analysis in highly inbred Arab and Druze families and differentiation from an ataxia-microcephaly-cataract syndrome
Ataxia-telangiectasia (A-T) is a progressive autosomal recessive disease featuring neurodegeneration, immunodeficiency, chromosomal instability, radiation sensitivity and a highly increased proneness to cancer. A-T is ethnically widespread and genetically heterogeneous, as indicated by the existence of four complementation groups in this disease. Several "A-T-like" genetic diseases share various clinical and cellular characteristics with A-T. By using linkage analysis to study North American and Turkish A-O families, the ATA (A-T, complementation group A) gene has been mapped to chromosome 11q23. A number of Israeli Arab A-T patients coming from large, highly inbred families were assigned to group A In one of these families, an additional autosomal recessive disease was identified, characterized by ataxia, hypotonia, microcephaly and bilateral congenital cataracts. In two patients with this syndrome, normal levels of serum immunoglobulins and alpha-fetoprotein, chromosomal stability in peripheral blood lymphocytes and skin fibroblasts, and normal cellular response to treatments with X-rays and the radiomimetic drug neocarzinostatin indicated that this disease does not share, with A-T, any additional features other than ataxia. These tests also showed that another patient in this family, who is also mentally retarded, is affected with both disorders. This conclusion was further supported by linkage analysis with 11q23 markers. Lod scores between A-O and these markers, cumulated over three large Arab families, were significant and confirmed the localization of the ATA gene to aq23. However, another Druze family unassigned to a specific complementation group, showed several recombinants between A-T and the same markers, leaving the localization of the A-T gene in this family open
Has the profile of heart transplantation recipients changed within the last three decades?
Heart transplantation remains the most durable treatment for patients with end-stage heart failure refractory to medical treatment. Central elements of the listing criteria for heart transplantation have remained largely unchanged in the last three decades whereas treatment of heart failure has significantly increased survival and reduced disease-related symptoms. It remains unknown whether the improvement of heart failure therapy changed the profile of heart transplantation candidates or affected post-transplant survival.
The study investigated a total of 323 heart transplant recipients of the Lausanne University Hospital with 328 transplant operations between 1987 and 2018. Patients were separated into three groups on the basis of availability of heart failure therapy: period 1 (1987-1998; n = 115) when renin-angiotensin system blockade and diuretic treatment were available; period 2 (1999-2010; n = 106) marked by the addition of beta-blocker and mineralocorticoid receptor antagonist treatment in severe heart failure, and the establishment of cardiac defibrillator and resynchronisation therapy; period 3 (2011-2018; n = 107) characterised by the increasing use of ventricular assist devices for bridge to transplantation.
The patient characteristics age (all: 53.4 years), male sex (all: 79%) and body mass index (all: 24.5 kg/m2) did not differ between periods. History of arterial hypertension was less prevalent in period 2 (period 1 vs 2 vs 3: 44 vs 28 vs 43%, p = 0.04) whereas other cardiovascular risk factors were equally distributed. Left ventricular ejection fraction, VO2max, and pulmonary vascular resistance were not different between the three periods. The prevalence of ischaemic cardiomyopathy was higher in periods 1 and 3; dilated non-ischaemic cardiomyopathy was more frequent in period 2. Post-transplant 1-year survival was highest in period 3 (1 vs 2 vs 3: 87.2 ± 3.2% vs 70.8 ± 4.4% vs 93.0 ± 2.6%, p always ≤0.02), and the Kaplan-Meier estimates of survivors of the first year post-transplant were not different between the three periods. In descriptive analysis, early mortality was not associated with acknowledged pretransplant predictors of post-transplant mortality.
Availability of different medical heart failure treatments did not result in greatly different pretransplant characteristics of heart transplantation recipients across the three periods. This suggests that the maintained central criteria of listing for heart transplantation still identify end-stage heart failure patients with a similar profile. This finding can explain the unchanged overall mortality on condition of 1-year survival across the three periods, since pretransplant characteristics are relevant for long-term survival after heart transplantation
Dualities and the phase diagram of the -clock model
A new "bond-algebraic" approach to duality transformations provides a very
powerful technique to analyze elementary excitations in the classical
two-dimensional XY and -clock models. By combining duality and Peierls
arguments, we establish the existence of non-Abelian symmetries, the phase
structure, and transitions of these models, unveil the nature of their
topological excitations, and explicitly show that a continuous U(1) symmetry
emerges when . This latter symmetry is associated with the appearance
of discrete vortices and Berezinskii-Kosterlitz-Thouless-type transitions. We
derive a correlation inequality to prove that the intermediate phase, appearing
for , is critical (massless) with decaying power-law correlations.Comment: 48 pages, 5 figures. Submitted to Nuclear Physics
Duration of androgen suppression before radiotherapy for localized prostate cancer: Radiation therapy oncology group randomized clinical trial 9910
Purpose To determine whether prolonged androgen suppression (AS) duration before radiotherapy improves survival and disease control in prostate cancer. Patients and Methods One thousand five hundred seventy-nine men with intermediate-risk prostate cancer were randomly assigned to 8 weeks of AS followed by radiotherapy with an additional 8 weeks of concurrent AS (16 weeks total) or to 28 weeks of AS followed by radiotherapy with an additional 8 weeks of AS (36 weeks total). The trial sought primarily to detect a 33% reduction in the hazard of prostate cancer death in the 28-week assignment. Time-to-event end points are reported for up to 10 years of follow-up. Results There were no between-group differences in baseline characteristics of 1,489 eligible patients with follow-up. For the 8- and 28-week assignments, 10-year disease-specific survival rates were 95% (95% CI, 93.3% to 97.0%) and 96% (95% CI, 94.6% to 98.0%; hazard ratio [HR], 0.81; P = .45), respectively, and 10-year overall survival rates were66%(95% CI, 62.0% to 69.9%) and67%(95% CI, 63.0% to 70.8%; HR, 0.95; P = .62), respectively. For the 8- and 28-week assignments, 10-year cumulative incidences of locoregional progression were 6% (95% CI, 4.3% to 8.0%) and 4% (95% CI, 2.5% to 5.7%; HR, 0.65; P = .07), respectively; 10-year distant metastasis cumulative incidences were 6% (95% CI, 4.0% to 7.7%) and 6% (95% CI, 4.0% to 7.6%; HR, 1.07; P = .80), respectively; and 10-year prostate-specific antigen-based recurrence cumulative incidences were 27% (95% CI, 23.1% to 29.8%) and 27% (95% CI, 23.4% to 30.3%; HR, 0.97; P = .77), respectively. Conclusion Extending AS duration from 8 weeks to 28 weeks before radiotherapy did not improve outcomes. A lower than expected prostate cancer death rate reduced ability to detect a between-group difference in disease-specific survival. The schedule of 8 weeks of AS before radiotherapy plus 8 weeks of AS during radiotherapy remains a standard of care in intermediate-risk prostate cancer
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