Casimir-like tunneling-induced electronic forces

We study the quantum forces that act between two nearby conductors due to electronic tunneling. We derive an expression for these forces by calculating the flux of momentum arising from the overlap of evanescent electronic fields. Our result is written in terms of the electronic reflection amplitudes of the conductors and it has the same structure as Lifshitz's formula for the electromagnetically mediated Casimir forces. We evaluate the tunneling force between two semiinfinite conductors and between two thin films separated by an insulating gap. We discuss some applications of our results.Comment: 8 pages, 3 figs, submitted to Proc. of QFEXT'05, to be published in J. Phys.

How expensive is treating patients in a center of excellence for rheumatoid arthritis in Colombia?

We aimed to estimate the cost of treating patients with rheumatoid arthritis (RA) in a Center of Excellence (CoE) for rheumatic diseases located in Bogotá, Colombia. We performed a cost analysis from the standard cost estimation of a CoE program for RA care. We estimated costs of consultations, laboratory and imaging tests, and pharmacological treatment from the measurement of the health care resource utilization of the CoE standard protocol according to the activity level of the disease (DAS28). Costing process was done following the recommendation of the Colombian Institute of Health Technology Assessment (IETS, in Spanish). Mean, minimum and maximum costs were reported annually for a type case depending on severity and classified as Remission, low disease activity (LDA), moderate disease activity (MDA) and severe disease activity -SDA- (with and without bDMARD). All costs were reported in American dollars, using the average exchange rate from January to December of 2018, reported by Banco de la República de Colombia: US$1 =$2,951.3 Colombian pesos. Mean total direct medical cost to treat a patient in remission is US$235.7 (213.0-336.4), in LDA is US325.2 (288.0-464.6) and in MDA is US$835.5 ($573.1-$2,187.1). There is a considerable increase in direct medical costs from a patient in SDA and SDA+Biologics: US$2,555.5 ($2,301.1-$3,890.9) to US$8,032.4 ($7,564.4-$8,400.3). The largest share of the cost was related to drugs, representing 39.9% for Remission, 53.6% for LDA, 75.2 for MDA, and in SDA and SDA+Biologics the proportion of what is spent on drugs for RA treatment is 88.5% and 96.7%, respectively. As the severity of the disease increases, the expenditure rate on drugs rises over the total of each activity level. With the introduction of the biological therapy, the treatment of RA is expensive, however, the CoE is an efficient way of care for RA

Strange matter in rotating compact stars

We have constructed equations of state involving various exotic forms of matter with large strangeness fraction such as hyperon matter, Bose-Einstein condensates of antikaons and strange quark matter. First order phase transitions from hadronic to antikaon condensed and quark matter are considered here. The hadronic phase is described by the relativistic field theoretical model. Later those equations of state are exploited to investigate models of uniformly rotating compact stars. The effect of rotation on the third family branch for the equation of state involving only antikaon condensates is investigated. We also discuss the back bending phenomenon due to a first order phase transition from $K^-$ condensed to quark matter.Comment: 8 pages, 4 figures; Plenary talk delivered at Strangeness in Quark Matter (SQM) 2004 held in Cape Town, South Africa from 15-20 September; Accepted for publication in the proceedings in Journal of Physics

Heat kernel expansion and induced action for matrix models

In this proceeding note, I review some recent results concerning the quantum effective action of certain matrix models, i.e. the supersymmetric IKKT model, in the context of emergent gravity. The absence of pathological UV/IR mixing is discussed, as well as dynamical SUSY breaking and some relations with string theory and supergravity.Comment: 11 pages, 1 figure; talk given at the 7th International Conference on Quantum Theory and Symmetries, August 7-13, 2011, Prague/Czech Republi

Computational design of dynamic receptor-peptide signaling complexes applied to chemotaxis.

Engineering protein biosensors that sensitively respond to specific biomolecules by triggering precise cellular responses is a major goal of diagnostics and synthetic cell biology. Previous biosensor designs have largely relied on binding structurally well-defined molecules. In contrast, approaches that couple the sensing of flexible compounds to intended cellular responses would greatly expand potential biosensor applications. Here, to address these challenges, we develop a computational strategy for designing signaling complexes between conformationally dynamic proteins and peptides. To demonstrate the power of the approach, we create ultrasensitive chemotactic receptor-peptide pairs capable of eliciting potent signaling responses and strong chemotaxis in primary human T cells. Unlike traditional approaches that engineer static binding complexes, our dynamic structure design strategy optimizes contacts with multiple binding and allosteric sites accessible through dynamic conformational ensembles to achieve strongly enhanced signaling efficacy and potency. Our study suggests that a conformationally adaptable binding interface coupled to a robust allosteric transmission region is a key evolutionary determinant of peptidergic GPCR signaling systems. The approach lays a foundation for designing peptide-sensing receptors and signaling peptide ligands for basic and therapeutic applications

Responses Of Lipids And Lipoproteins Following Acute And Training Resistance Exercise In Obese Postmenopausal Women

A single aerobic session and aerobic training can favorably modify lipids and lipoproteins in postmenopausal women, but the effects of a single resistance exercise session (RE) and resistance training (RT) remain equivocal. PURPOSE: To determine the acute effects of RE and chronic effects of 12 weeks of RT on lipid and lipoprotein-cholesterol concentrations in obese, postmenopausal women. METHODS: Sedentary, obese, non-smoking, postmenopausal women, not taking HRT, were divided into either an exercise group (E, n = 10; age = 65.7 ± 1.8 y; BMI = 32.6 ± 3.5 kg/m2) or control group (C, n = 11; age = 66.1 ± 3.0 y; BMI = 32.9 ± 4.3 kg/m2). Fasting (12 hr) blood samples were collected prior to and 24 hr after the first (BT) and last (AT) exercise session, and at the same time points for C. E performed ten upper and lower body resistance exercises (3 sets, 8 rep/set, 80% 1-RM) 3 times per week for 12 weeks; while C attended education classes twice per week for 12 weeks. Serum was assayed for total cholesterol, triglycerides, LDL-C, HDL-C, HDL2-C, HDL3-C concentrations. A 2 x 2 x 2 (group x training period x time) MANOVA was to determine changes in lipid and lipoprotein variables. A 2 x 2 (group x time) repeated measures ANOVA was used to assess body composition. RESULTS: The MANOVA revealed no significant changes in serum lipids or lipoproteins following RE or RT. No changes in body composition were observed post-training (P \u3e 0.05). Variable Pre-BT 24 hr BT Pre-AT 24 hr AT TC (mg/dl) C E 189 ± 28 217 ± 55 205 ± 40 212 ± 49 201 ± 48 207 ± 105 206 ± 42 195 ± 106 Tg (mg/dl) C E 107 ± 42 114 ± 40 96 ± 49 103 ± 25 116 ± 49 129 ± 92 112 ± 45 102 ± 48 LDL-C (mg/dl) C E 112 ± 26 140 ± 51 129 ± 37 137 ± 41 118 ± 40 127 ± 89 124 ± 41 120 ± 88 HDL-C (mg/dl) C E 55 ± 16 55 ± 12 57 ± 14 55 ±16 60 ± 13 53 ± 15 60 ± 16 54 ± 17 HDL2-C (mg/dl) C E 36 ± 12 36 ± 10 35 ± 10 34 ± 13 35 ± 12 33 ± 14 33 ± 16 35 ± 13 HDL3-C (mg/dl) C E 19 ± 9 19 ± 5 21 ± 7 21 ± 6 25 ± 6 20 ± 5 26 ± 6 20 ± 7 CONCLUSION: These data suggest that a single RE session and a 12-week RT program have no effect on lipids and lipoproteins. Compared to the effects of aerobic training, resistance exercise related changes in body composition may be necessary to modify lipids and lipoproteins in obese postmenopausal women

Deciphering the roadmap of in vivo reprogramming toward pluripotency

Differentiated cells can be converted into pluripotent stem cells by expressing the transcription factors OCT4, SOX2, KLF4, and MYC (OSKM) in a process known as reprogramming. Here, using single-cell RNA sequencing of pancreas undergoing reprogramming, we identify markers along the trajectory from acinar cell identity to pluripotency. These markers allow direct in situ visualization of cells undergoing dedifferentiation and acquiring features of early and advanced intermediate reprogramming. We also find that a fraction of cells do not dedifferentiate upon OSKM expression and are characterized by stress markers of the REG3 and AP-1 families. Importantly, most markers of intermediate reprogramming in the pancreas are also observed in stomach, colon, and cultured fibroblasts expressing OSKM. Among them is LY6A, a protein characteristic of progenitor cells and generally upregulated during tissue repair. Our roadmap defines intermediate reprogramming states that could be functionally relevant for tissue regeneration and rejuvenation.Copyright © 2022 The Author(s). Published by Elsevier Inc. All rights reserved

Generally covariant state-dependent diffusion

Statistical invariance of Wiener increments under SO(n) rotations provides a notion of gauge transformation of state-dependent Brownian motion. We show that the stochastic dynamics of non gauge-invariant systems is not unambiguously defined. They typically do not relax to equilibrium steady states even in the absence of extenal forces. Assuming both coordinate covariance and gauge invariance, we derive a second-order Langevin equation with state-dependent diffusion matrix and vanishing environmental forces. It differs from previous proposals but nevertheless entails the Einstein relation, a Maxwellian conditional steady state for the velocities, and the equipartition theorem. The over-damping limit leads to a stochastic differential equation in state space that cannot be interpreted as a pure differential (Ito, Stratonovich or else). At odds with the latter interpretations, the corresponding Fokker-Planck equation admits an equilibrium steady state; a detailed comparison with other theories of state-dependent diffusion is carried out. We propose this as a theory of diffusion in a heat bath with varying temperature. Besides equilibrium, a crucial experimental signature is the non-uniform steady spatial distribution.Comment: 24 page

Efecto del tratamiento postcosecha 1-MCP/CaCl₂ en la expresión de genes del metabolismo de la pared celular de frutilla

Debido a su textura delicada y velocidad elevada de ablandamiento, la frutilla, presenta una gran susceptibilidad al ataque por patógenos lo que reduce el tiempo de vida comercial de estos frutos. Por estos motivos, es de interés el desarrollo de tratamientos capaces de retrasar el desensamblaje de la pared celular, y el consecuente ablandamiento, durante la postcosecha de frutilla. En un trabajo previo realizado por nuestro grupo de investigación, se halló que frutos tratados con 1-metilciclopropeno (1-MCP) y con CaCl₂ y almacenados 10 días a 4 °C y 2 días a 20 °C, eran más firmes, presentaban un mayor contenido tanto de pectinas unidas por interacciones débiles e iónicas, así como de hemicelulosas en sus paredes celulares y eran más resistentes al ataque por Botrytis cinerea que los frutos controles. El objetivo del presente trabajo fue evaluar el efecto del tratamiento 1-MCP/CaCl₂ sobre la expresión de genes vinculados con el metabolismo de los polímeros constituyentes de la pared celular de frutilla. Para ello se utilizaron 400 frutos del cultivar Aroma cosechados en estadio de madurez comercial, los cuales se dividieron en 4 grupos: Control: 18 h aire, 20 °C + 30 min en agua, 25 °C; T1: 18 h aire, 20 °C + 30 min en CaCl₂ 1% p/v, 25 °C; T2: 18 h 1-MPC 1 ppm, 20 °C + 30 min en agua, 25 °C; y T3: 18 h 1-MCP 1 ppm, 20 °C + 30 min en CaCl₂ 1% p/v, 25 °C. Se tomaron muestras tanto inmediatamente después de los tratamientos (tiempo inicial, Ti) como luego de un almacenamiento de 10 días a 4 °C + 2 días a 20 °C (tiempo final, Tf). Mediante la técnica de PCR en Tiempo Real se midió la expresión de genes relevantes en el metabolismo de pectinas: poligalacturonasa (FaPG1) y pectin metilesterasa (FaPME1); y de hemicelulosas: xiloglucano endotransglicosilasa (FaXTH1) y xilosidasa (FaXyl1). Inmediatamente después de los tratamientos (Ti), se observó una expresión significativamente mayor de FaPME1 y una expresión significativamente menor de FaPG1 en los frutos T1, T2 y T3, respecto a los controles. Por otro lado, la expresión FaXTH1 fue significativamente mayor en frutos sometidos a los tratamientos individuales y combinado, respecto al control. Es de destacar que estos efectos fueron más marcados en frutos sometidos a los tratamientos con 1-MCP (T2) y combinado (T3). Respecto al gen FaXyl1 no se encontraron diferencias significativas en la expresión de mismo entre frutos tratados y controles. Estos resultados se encuentran estrechamente vinculados con el mayor contenido de pectinas de interacciones iónicas y débiles, así como de hemicelulosas registrados previamente.Trabajo publicado en Castagnini, Juan Manuel; Luz Marina Zapata; Liliana Mabel Gerard (eds.). Libro de Trabajos Completos I Congreso Argentino de Biología y Tecnología Poscosecha. IX Jornadas Argentinas de Biología y Tecnología Poscosecha. Paraná: Universidad Nacional de Entre Ríos, 2018.Facultad de Ciencias Agrarias y Forestale