143 research outputs found

    Asymptotics of self-similar solutions to coagulation equations with product kernel

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    We consider mass-conserving self-similar solutions for Smoluchowski's coagulation equation with kernel K(Ο,η)=(Οη)λK(\xi,\eta)= (\xi \eta)^{\lambda} with λ∈(0,1/2)\lambda \in (0,1/2). It is known that such self-similar solutions g(x)g(x) satisfy that x−1+2λg(x)x^{-1+2\lambda} g(x) is bounded above and below as x→0x \to 0. In this paper we describe in detail via formal asymptotics the qualitative behavior of a suitably rescaled function h(x)=hλx−1+2λg(x)h(x)=h_{\lambda} x^{-1+2\lambda} g(x) in the limit λ→0\lambda \to 0. It turns out that h∌1+Cxλ/2cos⁥(λlog⁥x)h \sim 1+ C x^{\lambda/2} \cos(\sqrt{\lambda} \log x) as x→0x \to 0. As xx becomes larger hh develops peaks of height 1/λ1/\lambda that are separated by large regions where hh is small. Finally, hh converges to zero exponentially fast as x→∞x \to \infty. Our analysis is based on different approximations of a nonlocal operator, that reduces the original equation in certain regimes to a system of ODE

    The BCS Functional for General Pair Interactions

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    The Bardeen-Cooper-Schrieffer (BCS) functional has recently received renewed attention as a description of fermionic gases interacting with local pairwise interactions. We present here a rigorous analysis of the BCS functional for general pair interaction potentials. For both zero and positive temperature, we show that the existence of a non-trivial solution of the nonlinear BCS gap equation is equivalent to the existence of a negative eigenvalue of a certain linear operator. From this we conclude the existence of a critical temperature below which the BCS pairing wave function does not vanish identically. For attractive potentials, we prove that the critical temperature is non-zero and exponentially small in the strength of the potential.Comment: Revised Version. To appear in Commun. Math. Phys

    Universal features of the order-parameter fluctuations : reversible and irreversible aggregation

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    We discuss the universal scaling laws of order parameter fluctuations in any system in which the second-order critical behaviour can be identified. These scaling laws can be derived rigorously for equilibrium systems when combined with the finite-size scaling analysis. The relation between order parameter, criticality and scaling law of fluctuations has been established and the connexion between the scaling function and the critical exponents has been found. We give examples in out-of-equilibrium aggregation models such as the Smoluchowski kinetic equations, or of at-equilibrium Ising and percolation models.Comment: 19 pages, 10 figure

    From TgO/GABA-AT, GABA, and T-263 Mutant to Conception of Toxoplasma

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    Toxoplasma gondii causes morbidity, mortality, and disseminates widely via cat sexual stages. Here, we find T. gondii ornithine aminotransferase (OAT) is conserved across phyla. We solve TgO/GABA-AT structures with bound inactivators at 1.55 Å and identify an inactivator selective for TgO/GABA-AT over human OAT and GABA-AT. However, abrogating TgO/GABA-AT genetically does not diminish replication, virulence, cyst-formation, or eliminate cat's oocyst shedding. Increased sporozoite/merozoite TgO/GABA-AT expression led to our study of a mutagenized clone with oocyst formation blocked, arresting after forming male and female gametes, with “Rosetta stone”-like mutations in genes expressed in merozoites. Mutations are similar to those in organisms from plants to mammals, causing defects in conception and zygote formation, affecting merozoite capacitation, pH/ionicity/sodium-GABA concentrations, drawing attention to cyclic AMP/PKA, and genes enhancing energy or substrate formation in TgO/GABA-AT-related-pathways. These candidates potentially influence merozoite's capacity to make gametes that fuse to become zygotes, thereby contaminating environments and causing disease

    Safety assessment of essential medicines for elderly people: a bibliographic survey

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    Certain medicines are considered potentially inappropriate (PIM) for elderly people as they increase the risk of adverse drug events (ADE) and because safer alternative therapies are available on the market. In this context, in order to identify the instruments that assess the quality of medical prescriptions for elderly and to determine which drugs are considered PIM, a bibliographic survey was conducted in PUBMED, LILACS and PAHO databases, in February and March/2010. The search strategy included the use of health descriptors and a manual search in the references cited by selected papers. During the period of data collection, 15 instruments were identified. In 2012, with the publication of the update of Beers criteria, this instrument was included in the study. We identified 163 PIM of 25 therapeutic classes, of which 125 (76.7%) are marketed in Brazil. Of these, 31 (24.8%) are essential medicines (RENAME 2012), of which 13 have safer therapeutic equivalents and 19 (15.2%) are over-the-counter drugs. Data suggest the need for inclusion of safer alternatives for the elderly in the national list of essential medicines and the pharmaceutical care for early detection of ADE in this age group, in order to contribute to the safe use of medicines

    Acceptance and commitment therapy for people living with motor neuron disease: an uncontrolled feasibility study

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    Background Motor neuron disease (MND) is a fatal, progressive neurodegenerative disease that causes progressive weakening and wasting of limb, bulbar, thoracic and abdominal muscles. Clear evidence-based guidance on how psychological distress should be managed in people living with MND (plwMND) is lacking. Acceptance and Commitment Therapy (ACT) is a form of psychological therapy that may be particularly suitable for this population. However, to the authors' knowledge, no study to date has evaluated ACT for plwMND. Consequently, the primary aim of this uncontrolled feasibility study was to examine the feasibility and acceptability of ACT for improving the psychological health of plwMND. Methods PlwMND aged ≄ 18 years were recruited from 10 UK MND Care Centres/Clinics. Participants received up to 8 one-to-one ACT sessions, developed specifically for plwMND, plus usual care. Co-primary feasibility and acceptability outcomes were uptake (≄ 80% of the target sample [N = 28] recruited) and initial engagement with the intervention (≄ 70% completing ≄ 2 sessions). Secondary outcomes included measures of quality of life, anxiety, depression, disease-related functioning, health status and psychological flexibility in plwMND and quality of life and burden in caregivers. Outcomes were assessed at baseline and 6 months. Results Both a priori indicators of success were met: 29 plwMND (104%) were recruited and 76% (22/29) attended ≄ 2 sessions. Attrition at 6-months was higher than anticipated (8/29, 28%), but only two dropouts were due to lack of acceptability of the intervention. Acceptability was further supported by good satisfaction with therapy and session attendance. Data were possibly suggestive of small improvements in anxiety and psychological quality of life from baseline to 6 months in plwMND, despite a small but expected deterioration in disease-related functioning and health status. Conclusions There was good evidence of acceptability and feasibility. Limitations included the lack of a control group and small sample size, which complicate interpretation of findings. A fully powered RCT to evaluate the clinical and cost-effectiveness of ACT for plwMND is underway

    Galaxy bulges and their massive black holes: a review

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    With references to both key and oft-forgotten pioneering works, this article starts by presenting a review into how we came to believe in the existence of massive black holes at the centres of galaxies. It then presents the historical development of the near-linear (black hole)-(host spheroid) mass relation, before explaining why this has recently been dramatically revised. Past disagreement over the slope of the (black hole)-(velocity dispersion) relation is also explained, and the discovery of sub-structure within the (black hole)-(velocity dispersion) diagram is discussed. As the search for the fundamental connection between massive black holes and their host galaxies continues, the competing array of additional black hole mass scaling relations for samples of predominantly inactive galaxies are presented.Comment: Invited (15 Feb. 2014) review article (submitted 16 Nov. 2014). 590 references, 9 figures, 25 pages in emulateApJ format. To appear in "Galactic Bulges", E. Laurikainen, R.F. Peletier, and D.A. Gadotti (eds.), Springer Publishin

    Risk profiles and one-year outcomes of patients with newly diagnosed atrial fibrillation in India: Insights from the GARFIELD-AF Registry.

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    BACKGROUND: The Global Anticoagulant Registry in the FIELD-Atrial Fibrillation (GARFIELD-AF) is an ongoing prospective noninterventional registry, which is providing important information on the baseline characteristics, treatment patterns, and 1-year outcomes in patients with newly diagnosed non-valvular atrial fibrillation (NVAF). This report describes data from Indian patients recruited in this registry. METHODS AND RESULTS: A total of 52,014 patients with newly diagnosed AF were enrolled globally; of these, 1388 patients were recruited from 26 sites within India (2012-2016). In India, the mean age was 65.8 years at diagnosis of NVAF. Hypertension was the most prevalent risk factor for AF, present in 68.5% of patients from India and in 76.3% of patients globally (P < 0.001). Diabetes and coronary artery disease (CAD) were prevalent in 36.2% and 28.1% of patients as compared with global prevalence of 22.2% and 21.6%, respectively (P < 0.001 for both). Antiplatelet therapy was the most common antithrombotic treatment in India. With increasing stroke risk, however, patients were more likely to receive oral anticoagulant therapy [mainly vitamin K antagonist (VKA)], but average international normalized ratio (INR) was lower among Indian patients [median INR value 1.6 (interquartile range {IQR}: 1.3-2.3) versus 2.3 (IQR 1.8-2.8) (P < 0.001)]. Compared with other countries, patients from India had markedly higher rates of all-cause mortality [7.68 per 100 person-years (95% confidence interval 6.32-9.35) vs 4.34 (4.16-4.53), P < 0.0001], while rates of stroke/systemic embolism and major bleeding were lower after 1 year of follow-up. CONCLUSION: Compared to previously published registries from India, the GARFIELD-AF registry describes clinical profiles and outcomes in Indian patients with AF of a different etiology. The registry data show that compared to the rest of the world, Indian AF patients are younger in age and have more diabetes and CAD. Patients with a higher stroke risk are more likely to receive anticoagulation therapy with VKA but are underdosed compared with the global average in the GARFIELD-AF. CLINICAL TRIAL REGISTRATION-URL: http://www.clinicaltrials.gov. Unique identifier: NCT01090362

    Psicopatologia descritiva: aspectos histĂłricos e conceituais

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