Bose-Einstein transition temperature in a dilute repulsive gas

We discuss certain specific features of the calculation of the critical temperature of a dilute repulsive Bose gas. Interactions modify the critical temperature in two different ways. First, for gases in traps, temperature shifts are introduced by a change of the density profile, arising itself from a modification of the equation of state of the gas (reduced compressibility); these shifts can be calculated simply within mean field theory. Second, even in the absence of a trapping potential (homogeneous gas in a box), temperature shifts are introduced by the interactions; they arise from the correlations introduced in the gas, and thus lie inherently beyond mean field theory - in fact, their evaluation requires more elaborate, non-perturbative, calculations. One illustration of this non-perturbative character is provided by the solution of self-consistent equations, which relate together non-linearly the various energy shifts of the single particle levels k. These equations predict that repulsive interactions shift the critical temperature (at constant density) by an amount which is positive, and simply proportional to the scattering length a; nevertheless, the numerical coefficient is difficult to compute. Physically, the increase of the temperature can be interpreted in terms of the reduced density fluctuations introduced by the repulsive interactions, which facilitate the propagation of large exchange cycles across the sample.Comment: two minor corrections, two refs adde

Dynamique De La Population De La Crevette D’eau Douce Atya Scabra (Leach, 1815) (Decapoda: Atyidae) Dans La Rivière Bia, Région Du Sud-Comoé (Côte d’Ivoire)

The parameters of growth, mortality, the exploitation and the recruitment of Atya scabra (Leach, 1815) as traditionally fished in the Bia river, were studied. These parameters were determined from the size frequencies by the FiSAT II software. The results obtained at the specimens of Aboisso were:= 156,45 mm, K = 1,50 year -1, Φ' = 4,56, Z = 5,72 year -1, M = 1,48 year -1, F = 4,24 year -1 and E = 0,74 year -1. In Biaka, theestimated values were: L = 140,7 mm, K = 0,68 year -1, Φ' = 4,13, Z = 1,52year -1, M = 0,91 year -1, F = 0,61 year -1 and E = 0,40 year -1 . Aboisso specimens have a higher growth performance index (Φ') than Biaka's and a weak longevity (tmax = 2 years) compared to Biaka (tmax = 4.41 years). Shrimps are under exploited in the locality of Biaka (E 0.5). Total mortality is higher in Aboisso than in Biaka. However, the survival rate recorded in Aboisso (S = 0.003 years) is lower than that of Biaka (S = 0.22 years). Recruitment is continuous throughout the year, with two peaks (a major peak in September and a minor peak in February) in Aboisso. As for Biaka, the presence of a normal distribution indicates that recruitment is single. These results will serve as a database for rational management of A. scabra

Cine and tagged cardiovascular magnetic resonance imaging in normal rat at 1.5 T: a rest and stress study

BACKGROUND: The purpose of this study was to measure regional contractile function in the normal rat using cardiac cine and tagged cardiovascular magnetic resonance (CMR) during incremental low doses of dobutamine and at rest. METHODS: Five rats were investigated for invasive left ventricle pressure measurements and five additional rats were imaged on a clinical 1.5 T MR system using a cine sequence (11-20 phases per cycle, 0.28/0.28/2 mm) and a C-SPAMM tag sequence (18-25 phases per cycle, 0.63/1.79/3 mm, tag spacing 1.25 mm). For each slice, wall thickening (WT) and circumferential strains (CS) were calculated at rest and at stress (2.5, 5 and 10 microg/min/kg of dobutamine). RESULTS: Good cine and tagged images were obtained in all the rats even at higher heart rate (300-440 bpm). Ejection fraction and left ventricular (LV) end-systolic volume showed significant changes after each dobutamine perfusion dose (p < 0.001). Tagged CMR had the capacity to resolve the CS transmural gradient and showed a significant increase of both WT and CS at stress compared to rest. Intra and interobserver study showed less variability for the tagged technique. In rats in which a LV catheter was placed, dobutamine produced a significant increase of heart rate, LV dP/dtmax and LV pressure significantly already at the lowest infusion dose. CONCLUSION: Robust cardiac cine and tagging CMR measurements can be obtained in the rat under incremental dobutamine stress using a clinical 1.5 T MR scanner

Teoría del cine (Mesa redonda con Christian Metz y otros)

Metz, C.; Fano, M.; Simon, J.; Simsolo, N. (1978). Teoría del cine (Mesa redonda con Christian Metz y otros). La mirada. (1):31-39. http://hdl.handle.net/10251/41550.Importación Masiva3139

Synchronization of patient data among health facilities through electronic medical records system: a case study of Kabgayi District Hospital

Background: The use of modern technology in healthcare system aims to increase the reliability, accessibility and productivity of delivered services. In most developing countries, particularly in sub-Saharan Africa, Electronic Medical Records (EMRs) has been dominated by paper-based system. In Rwanda, EMRs started in 2011 with a baseline of 8% and reached 50% in 2017 within 516 health facilities, but patient data synchronization among health facilities is still a problem. The aim of this research was to identify factors hindering EMRs implementation and propose applied solutions.Methods: A cross-sectional descriptive study design with qualitative and quantitative approach was used. A purposive method to select the research participants among the target population was also used.Results: It was found that, despite the improvement of hospitals’ management and healthcare efficiency via EMRs system, factors affecting synchronization of patients’ data among health facilities still persist. The study also revealed the need for the interoperability in the integration of EMRs system among health facilities.Conclusion: The OpenMRS EMR-based data synchronization can reduce gaps in HIV care. It avoids a duplication of patient identification number (PID) at the same health facility for more than one visit and missing data among health facilities. As part of implementable solutions for effective service delivery, cloud-based server and patient identification were suggested as solutions for much more success in Open MRS EMRs system.Keywords: Electronic Medical Record, Data synchronization, Cloud computing technolog

The wheelchair as a full-body tool extending the peripersonal space

Dedicated multisensory mechanisms in the brain represent peripersonal space (PPS), a limited portion of space immediately surrounding the body. Previous studies have illustrated the malleability of PPS representation through hand-object interaction, showing that tool use extends the limits of the hand-centered PPS. In the present study we investigated the effects of a special tool, the wheelchair, in extending the action possibilities of the whole body. We used a behavioral measure to quantify the extension of the PPS around the body before and after Active (Experiment 1) and Passive (Experiment 2) training with a wheelchair and when participants were blindfolded (Experiment 3). Results suggest that a wheelchair-mediated passive exploration of far space extended PPS representation. This effect was specifically related to the possibility of receiving information from the environment through vision, since no extension effect was found when participants were blindfolded. Surprisingly, the active motor training did not induce any modification in PPS representation, probably because the wheelchair maneuver was demanding for non-expert users and thus they may have prioritized processing of information from close to the wheelchair rather than at far spatial locations. Our results suggest that plasticity in PPS representation after tool use seems not to strictly depend on active use of the tool itself, but is triggered by simultaneous processing of information from the body and the space where the body acts in the environment, which is more extended in the case of wheelchair use. These results contribute to our understanding of the mechanisms underlying body environment interaction for developing and improving applications of assistive technological devices in different clinical populations

Peri-personal space as a prior in coupling visual and proprioceptive signals

Abstract It has been suggested that the integration of multiple body-related sources of information within the peri-personal space (PPS) scaffolds body ownership. However, a normative computational framework detailing the functional role of PPS is still missing. Here we cast PPS as a visuo-proprioceptive Bayesian inference problem whereby objects we see in our environment are more likely to engender sensations as they come near to the body. We propose that PPS is the reflection of such an increased a priori probability of visuo-proprioceptive coupling that surrounds the body. To test this prediction, we immersed participants in a highly realistic virtual reality (VR) simulation of their right arm and surrounding environment. We asked participants to perform target-directed reaches toward visual, proprioceptive, and visuo-proprioceptive targets while visually displaying their reaching arm (body visible condition) or not (body invisible condition). Reach end-points are analyzed in light of the coupling prior framework, where the extension of PPS is taken to be represented by the spatial dispersion of the coupling prior between visual and proprioceptive estimates of arm location. Results demonstrate that if the body is not visible, the spatial dispersion of the visuo-proprioceptive coupling relaxes, whereas the strength of coupling remains stable. By demonstrating a distance-dependent alteration in visual and proprioceptive localization attractive pull toward one another (stronger pull at small spatial discrepancies) when the body is rendered invisible – an effect that is well accounted for by the visuo-proprioceptive coupling prior – the results suggest that the visible body grounds visuo-proprioceptive coupling preferentially in the near vs. far space

PAI-1 Regulates the Invasive Phenotype in Human Cutaneous Squamous Cell Carcinoma

The emergence of highly aggressive subtypes of human cutaneous squamous cell carcinoma (SCC) often reflects increased autocrine/paracrine TGF-β synthesis and epidermal growth factor receptor (EGFR) amplification. Cooperative TGF-β/EGFR signaling promotes cell migration and induces expression of both proteases and protease inhibitors that regulate stromal remodeling resulting in the acquisition of an invasive phenotype. In one physiologically relevant model of human cutaneous SCC progression, TGF-β1+EGF stimulation increases the production of several matrix metalloproteinases (MMPs), among the most prominent of which is MMP-10—an MMP known to be elevated in SCC in situ. Activation of stromal plasminogen appears to be critical in triggering downstream MMP activity. Paradoxically, PAI-1, the major physiological inhibitor of plasmin generation, is also upregulated under these conditions and is an early event in progression of incipient epidermal SCC. One testable hypothesis proposes that TGF-β1+EGF-dependent MMP-10 elevation directs focalized matrix remodeling events that promote epithelial cell plasticity and tissue invasion. Increased PAI-1 expression serves to temporally and spatially modulate plasmin-initiated pericellular proteolysis, further facilitating epithelial invasive potential. Defining the complex signaling and transcriptional mechanisms that maintain this delicate balance is critical to developing targeted therapeutics for the treatment of human cutaneous malignancies