Irreversible flow of vortex matter: polycrystal and amorphous phases

We investigate the microscopic mechanisms giving rise to plastic depinning and irreversible flow in vortex matter. The topology of the vortex array crucially determines the flow response of this system. To illustrate this claim, two limiting cases are considered: weak and strong pinning interactions. In the first case disorder is strong enough to introduce plastic effects in the vortex lattice. Diffraction patterns unveil polycrystalline lattice topology with dislocations and grain boundaries determining the electromagnetic response of the system. Filamentary flow is found to arise as a consequence of dislocation dynamics. We analize the stability of vortex lattices against the formation of grain boundaries, as well as the steady state dynamics for currents approaching the depinning critical current from above, when vortex motion is mainly localized at the grain boundaries. On the contrary, a dislocation description proves no longer adequate in the second limiting case examined. For strong pinning interactions, the vortex array appears completely amorphous and no remnant of the Abrikosov lattice order is left. Here we obtain the critical current as a function of impurity density, its scaling properties, and characterize the steady state dynamics above depinning. The plastic depinning observed in the amorphous phase is tightly connected with the emergence of channel-like flow. Our results suggest the possibility of establishing a clear distinction between two topologically disordered vortex phases: the vortex polycrystal and the amorphous vortex matter.Comment: 13 pages, 16 figure

An interior-point method for mpecs based on strictly feasible relaxations.

An interior-point method for solving mathematical programs with equilibrium constraints (MPECs) is proposed. At each iteration of the algorithm, a single primaldual step is computed from each subproblem of a sequence. Each subproblem is defined as a relaxation of the MPEC with a nonempty strictly feasible region. In contrast to previous approaches, the proposed relaxation scheme preserves the nonempty strict feasibility of each subproblem even in the limit. Local and superlinear convergence of the algorithm is proved even with a less restrictive strict complementarity condition than the standard one. Moreover, mechanisms for inducing global convergence in practice are proposed. Numerical results on the MacMPEC test problem set demonstrate the fast-local convergence properties of the algorithm

AN INTERIOR-POINT METHOD FOR MPECs BASED ON STRICTLY FEASIBLE RELAXATIONS.

An interior-point method for solving mathematical programs with equilibrium constraints (MPECs) is proposed. At each iteration of the algorithm, a single primaldual step is computed from each subproblem of a sequence. Each subproblem is defined as a relaxation of the MPEC with a nonempty strictly feasible region. In contrast to previous approaches, the proposed relaxation scheme preserves the nonempty strict feasibility of each subproblem even in the limit. Local and superlinear convergence of the algorithm is proved even with a less restrictive strict complementarity condition than the standard one. Moreover, mechanisms for inducing global convergence in practice are proposed. Numerical results on the MacMPEC test problem set demonstrate the fast-local convergence properties of the algorithm.

Complete breakdown of the Debye model of rotational relaxation near the isotropic-nematic phase boundary: Effects of intermolecular correlations in orientational dynamics

The Debye-Stokes-Einstein (DSE) model of rotational diffusion predicts that the rotational correlation times $\tau_{l}$ vary as $[l(l+1)]^{-1}$, where $l$ is the rank of the orientational correlation function (given in terms of the Legendre polynomial of rank $l$). One often finds significant deviation from this prediction, in either direction. In supercooled molecular liquids where the ratio $\tau_{1}/\tau_{2}$ falls considerably below three (the Debye limit), one usually invokes a jump diffusion model to explain the approach of the ratio $\tau_{1}/\tau_{2}$ to unity. Here we show in a computer simulation study of a standard model system for thermotropic liquid crystals that this ratio becomes much less than unity as the isotropic-nematic phase boundary is approached from the isotropic side. Simultaneously, the ratio $\tau_2/\eta$ (where $\eta$ is the shear viscosity of the liquid) becomes {\it much larger} than hydrodynamic value near the I-N transition. We have also analyzed the break down of the Debye model of rotational diffusion in ratios of higher order rotational correlation times. We show that the break down of the DSE model is due to the growth of orientational pair correlation and provide a mode coupling theory analysis to explain the results.Comment: Submitted to Physical Review

Effectiveness and process evaluation in obesity and type 2 diabetes prevention programs in children: a systematic review and meta-analysis

Background: Obesity in children is one of the most severe public health challenges of the current century and Type 2 Diabetes Mellitus (T2DM) frequency is also escalating. More so, the importance of process evaluation (PE) in complex interventions is increasingly recognized. The present review, aims to identify the effectiveness in terms of body composition parameters in a generation of articles to prevent obesity and T2DM in children. We hypothesise that those studies reporting PE applying the latest implementation guidelines suggested by the researchers would potentially show positive changes in body composition compared to those not reporting it. Additionally, we will evaluate the implementation degree of PE in those articles considering it and describe the PE subcomponents. Lastly, we aim to assess the intervention target used and its results. Methods: A literature review was performed in parallel by 2 independent reviewers. A final number of 41 studies were selected for inclusion criteria. Results: Meta-analysis of BMI and zBMI found non-significant effects of the proposed interventions. Sub-group analysis revealed only a significant effect in studies which performed PE. Moreover, PE was reported in 42% effective studies and 57% non-effective studies. Fidelity and satisfaction were the most implemented PE subcomponents, although there was a generally low grade of PE use (7/41). The highest proportion of effectiveness (83%) was shown in interventions of physical activity alone while the intervention most used was 3-arm target (diet, PA and BS). Conclusions: Overall, obesity and T2DM prevention studies included in this review are not effective in terms of BMI and zBMI. Those studies performing PE reported to be effective in terms of BMI, while studies not reporting PE did not have positive results in terms of BMI and zBMI. In addition, none of the intervention studies included all PE indicators and most studies, which included PE in their interventions, did not provide full report of the PE components, according to the guidelines used for the present review. PROSPERO registration number: CRD42018093667

Primordial Germ Cell Reprogramming

Primordial germ cells (PGCs) are the embryonic precursors of the gametes. Thus, they are unipotent cells. However, PGCs share some common features with pluripotent stem cells. Among them, PGCs show alkaline phosphatase activity and express stage-specific embryonic antigens and pluripotency factors Lin28, Oct4, Sox2, and Nanog. Under specific conditions, they undergo spontaneous reprogramming in vivo. Moreover, they can be easily reprogrammed in vitro into pluripotent embryonic germ cells (EGCs) by culturing them in the presence of basic fibroblast growth factor or the epigenetic modulator trichostatin A. Previous work in our laboratory has also proven that hypoxia alone can reprogram PGCs into hypoxia-induced embryonic germ-like cells, which have a pluripotent phenotype but which do not show self-renewal capacity. Therefore, PGCs are an interesting model to further comprehensively understand the process of cell reprogramming. This chapter reviews various methods to achieve PGC reprogramming, as well as the molecular pathways involved. We focus on soluble factors and genetic strategies to obtain pluripotent cells from PGCs. Special emphasis will be given to factors implied in energetic metabolism, epigenetics, and cell signaling transduction, both in vitro and in vivo

CANFOR Portuguese version: validation study

This study is embedded in the larger project "Needs Assessment of the Mentally Disordered Prisoners" funded by Fundacao para a Ciencia e Tecnologia (PIC/IC/83257/2007). We acknowledge the General-Director for Prison Services for his authorization, the Prisons' Directors for their support, the medical and non-medical staff who collaborated in this study and detainees for their participation. Special thanks to Dr Ana Cabral for her support inside the prisons and Dr Jorge Pereira for his assistance in manuscript preparation. In memory of our late friend Dr Jose Morais, who collaborated on and supported this study from the beginning.BACKGROUND The increase in prisoner population is a troublesome reality in several regions of the world. Along with this growth there is increasing evidence that prisoners have a higher proportion of mental illnesses and suicide than the general population. In order to implement strategies that address criminal recidivism and the health and social status of prisoners, particularly in mental disordered offenders, it is necessary to assess their care needs in a comprehensive, but individual perspective. This assessment must include potential harmful areas like comorbid personality disorder, substance misuse and offending behaviours. The Camberwell Assessment of Need - Forensic Version (CANFOR) has proved to be a reliable tool designed to accomplish such aims. The present study aimed to validate the CANFOR Portuguese version. METHODS The translation, adaptation to the Portuguese context, back-translation and revision followed the usual procedures. The sample comprised all detainees receiving psychiatric care in four forensic facilities, over a one year period. A total of 143 subjects, and respective case manager, were selected. The forensic facilities were chosen by convenience: one prison hospital psychiatric ward (n=68; 47.6%), one male (n=24; 16.8%) and one female (n=22; 15.4%) psychiatric clinic and one civil security ward (n=29; 20.3%), all located nearby Lisbon. Basic descriptive statistics and Kappa weighted coefficients were calculated for the inter-rater and the test-retest reliability studies. The convergent validity was evaluated using the Global Assessment of Functioning and the Brief Psychiatric Rating Scale scores. RESULTS The majority of the participants were male and single, with short school attendance, and accused of a crime involving violence against persons. The most frequent diagnosis was major depression (56.1%) and almost half presented positive suicide risk. The reliability study showed average Kappa weighted coefficients of 0.884 and 0.445 for inter-rater and test-retest agreement, respectively. The convergent validity study presented highly significant correlations between unmet needs scores, GAF and BPRS scores. CONCLUSIONS The CANFOR Portuguese version revealed similar psychometric properties to the original English version. Moreover, the results of the reliability and validity studies indicate that the tool is appropriate for individual care needs assessment and as a guide for the mental health and social interventions in forensic psychiatric services.publishersversionpublishe

Cycling of Dense Core Vesicles Involved in Somatic Exocytosis of Serotonin by Leech Neurons

We studied the cycling of dense core vesicles producing somatic exocytosis of serotonin. Our experiments were made using electron microscopy and vesicle staining with fluorescent dye FM1-43 in Retzius neurons of the leech, which secrete serotonin from clusters of dense core vesicles in a frequency-dependent manner. Electron micrographs of neurons at rest or after 1 Hz stimulation showed two pools of dense core vesicles. A perinuclear pool near Golgi apparatuses, from which vesicles apparently form, and a peripheral pool with vesicle clusters at a distance from the plasma membrane. By contrast, after 20 Hz electrical stimulation 47% of the vesicle clusters were apposed to the plasma membrane, with some omega exocytosis structures. Dense core and small clear vesicles apparently originating from endocytosis were incorporated in multivesicular bodies. In another series of experiments, neurons were stimulated at 20 Hz while bathed in a solution containing peroxidase. Electron micrographs of these neurons contained gold particles coupled to anti-peroxidase antibodies in dense core vesicles and multivesicular bodies located near the plasma membrane. Cultured neurons depolarized with high potassium in the presence of FM1-43 displayed superficial fluorescent spots, each reflecting a vesicle cluster. A partial bleaching of the spots followed by another depolarization in the presence of FM1-43 produced restaining of some spots, other spots disappeared, some remained without restaining and new spots were formed. Several hours after electrical stimulation the FM1-43 spots accumulated at the center of the somata. This correlated with electron micrographs of multivesicular bodies releasing their contents near Golgi apparatuses. Our results suggest that dense core vesicle cycling related to somatic serotonin release involves two steps: the production of clear vesicles and multivesicular bodies after exocytosis, and the formation of new dense core vesicles in the perinuclear region