1,250 research outputs found

    A blob method for diffusion

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    As a counterpoint to classical stochastic particle methods for diffusion, we develop a deterministic particle method for linear and nonlinear diffusion. At first glance, deterministic particle methods are incompatible with diffusive partial differential equations since initial data given by sums of Dirac masses would be smoothed instantaneously: particles do not remain particles. Inspired by classical vortex blob methods, we introduce a nonlocal regularization of our velocity field that ensures particles do remain particles, and we apply this to develop a numerical blob method for a range of diffusive partial differential equations of Wasserstein gradient flow type, including the heat equation, the porous medium equation, the Fokker-Planck equation, the Keller-Segel equation, and its variants. Our choice of regularization is guided by the Wasserstein gradient flow structure, and the corresponding energy has a novel form, combining aspects of the well-known interaction and potential energies. In the presence of a confining drift or interaction potential, we prove that minimizers of the regularized energy exist and, as the regularization is removed, converge to the minimizers of the unregularized energy. We then restrict our attention to nonlinear diffusion of porous medium type with at least quadratic exponent. Under sufficient regularity assumptions, we prove that gradient flows of the regularized energies converge to solutions of the porous medium equation. As a corollary, we obtain convergence of our numerical blob method, again under sufficient regularity assumptions. We conclude by considering a range of numerical examples to demonstrate our method's rate of convergence to exact solutions and to illustrate key qualitative properties preserved by the method, including asymptotic behavior of the Fokker-Planck equation and critical mass of the two-dimensional Keller-Segel equation

    The Hunt for the Rest of the Higgs Bosons

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    We assess the current state of searches at the LHC for additional Higgs bosons in light of both direct limits and indirect bounds coming from coupling measurements of the Standard Model-like Higgs boson. Given current constraints, we identify and study three LHC searches that are critical components of a comprehensive program to investigate extended electroweak symmetry breaking sectors: production of a heavy scalar or pseudoscalar with decay to ttˉt \bar t; bbˉb \bar b and ttˉt \bar t associated production of a heavy scalar or pseudoscalar with decay to invisible final states; and tbˉt \bar b associated production of a charged Higgs with decay to tˉb\bar t b. Systematic experimental searches in these channels would contribute to robust coverage of the possible single production modes of additional heavy Higgs bosons.Comment: 44 pp., 23 fi

    Survival outcome and EMT suppression mediated by a lectin domain interaction of Endo180 and CD147

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    Epithelial cell-cell contacts maintain normal glandular tissue homeostasis, and their breakage can trigger epithelial-to-mesenchymal transition (EMT), a fundamental step in the development of metastatic cancer. Despite the ability of C-type lectin domains (CTLD) to modulate cell-cell adhesion, it is not known if they modulate epithelial adhesion in EMT and tumor progression. Here, the multi-CTLD mannose receptor, Endo180 (MRC2/uPARAP), was shown using the Kaplan-Meier analysis to be predictive of survival outcome in men with early prostate cancer. A proteomic screen of novel interaction partners with the fourth CTLD (CTLD4) in Endo180 revealed that its complex with CD147 is indispensable for the stability of three-dimensional acini formed by nontransformed prostate epithelial cells (PEC). Mechanistic study using knockdown of Endo180 or CD147, and treatment with an Endo180 mAb targeting CTLD4 (clone 39.10), or a dominant-negative GST-CTLD4 chimeric protein, induced scattering of PECs associated with internalization of Endo180 into endosomes, loss of E-cadherin (CDH1/ECAD), and unzipping of cell-cell junctions. These findings are the first to demonstrate that a CTLD acts as a suppressor and regulatory switch for EMT; thus, positing that stabilization of Endo180-CD147 complex is a viable therapeutic strategy to improve rates of prostate cancer survival

    A review of executive function deficits in autism spectrum disorder and attention-deficit/hyperactivity disorder

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    Executive dysfunction has been shown to be a promising endophenotype in neurodevelopmental disorders such as autism spectrum disorder (ASD) and attention-deficit/hyperactivity disorder (ADHD). This article reviewed 26 studies that examined executive function comparing ASD and/or ADHD children. In light of findings from this review, the ASD + ADHD group appears to share impairment in both flexibility and planning with the ASD group, while it shares the response inhibition deficit with the ADHD group. Conversely, deficit in attention, working memory, preparatory processes, fluency, and concept formation does not appear to be distinctive in discriminating from ASD, ADHD, or ASD + ADHD group. On the basis of neurocognitive endophenotype, the common co-occurrence of executive function deficits seems to reflect an additive comorbidity, rather than a separate condition with distinct impairments

    The Concurrent Validity of Two Relational Selfhood Models: A Pilot Study

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    The purpose of this study was to evaluate the concurrent validity of two instruments: the Self-Other Profile Chart (SOPC) derived from one model of Relational Competence Theory (RCT) and the How You View Your Self (HYVYS) derived from the Elementary Pragmatic Model (EPM). These two instruments were administered together with the Brief Psychiatric Rating Inventory (BPRI) to two samples of women and men with and without psychiatric diagnoses. Scores in both instruments demonstrated statistically significant test-retest reliabilities and correlated highly with scores on the BPRI. These results tend to support the concurrent validity of both instruments and add more evidence to the theoretical significance of the models they represent

    Psychopathology, symptoms of attention-deficit/hyperactivity disorder, and risk factors in juvenile offenders

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    Background: The aim of this study was to assess the prevalence of potential environmental and psychopathological risk factors, with special focus on symptoms of attention-deficit/hyperactivity disorder (ADHD), in a sample of adolescent offenders in relation to the type of crime committed. Methods: The assessment included data collection and administration of clinical standardized scales such as the Youth Self-Report and Conners’ Adolescent Self-Report Scale. A total of 135 juvenile offenders participated in the study. In relation to the type of crime committed, we identified three groups matched for age and sex (crimes against people, property crimes, and alcohol-drug-related crimes). Results: Fifty-two percent of juvenile offenders reported educational achievement problems and 34% reported a family history of psychiatric disorders. We detected a statistically significant difference between the three groups with regard to ADHD (P=0.01) and conduct problems (P=0.034). Juvenile offenders who had committed crimes against people showed more ADHD symptoms (18%) and conduct problems (20%) than adolescents who had committed property crimes and alcohol-drug-related crimes. Sixty percent of the juvenile offenders who had committed property crimes and 54% of those who had committed alcohol-drug-related crimes showed problems in academic achievement. Conclusion: These findings suggest the need to implement specific interventions for prevention and treatment of specific criminal behavior

    Executive Functions and Deafness: Results in a Group of Cochlear Implanted Children

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    Objects: This study aimed to evaluate the Executive Function (EF) domains in a group of profoundly deaf children treated with cochlear implant (CI) in comparison to normal hearing (NH) children. The secondary aim was to evaluate the influence exerted by the age at cochlear implant activation on EFs. Materials and Methods: 32 children were enrolled into two groups: group A of 17 CI users with a mean age of 8.78 years and group B of 15 NH subjects with a mean age of 7.99 years (SD + 2.3). All subjects were tested using the following tests: the subtests for working memory of the neuropsychological evaluation battery for the developmental age (Batteria di valutazione neuropsicologica per l’età evolutive), inhibition and control of the impulsive response—CAF, and the tower of London test. Results: No children with CIs scored within the normal range in the tests administered for the evaluation of EF domains. The same scores were significantly lower when compared with scores obtained by NH children. Children with younger age at CI activation showed better executive performances in planning, working memory (backward digit span), and cognitive flexibility (categorical fluency). Conclusion: The results of this study highlight that cochlear implantation plays a role in improving hearing and consequently influences the development of EFs in deaf children
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