A Semi-Deterministic Random Walk with Resetting.

We consider a discrete-time random walk (xt) which, at random times, is reset to the starting position and performs a deterministic motion between them. We show that the quantity Prxt+1=n+1|xt=n,n→∞ determines if the system is averse, neutral or inclined towards resetting. It also classifies the stationary distribution. Double barrier probabilities, first passage times and the distribution of the escape time from intervals are determined.

Primer aislamiento de Candida auris en Chile / First isolation de Candida auris in Chile

Resumen Candida auris es una levadura multi-resistente emergente con rápida diseminación mundial. Desde el primer reporte el 2009, varios aislados a través de los cinco continentes han sido identificados como agentes de infecciones asociadas a la atención en salud. Brotes independientes y simultáneos por C. auris se han vuelto prioridad para la comunidad hospitalaria y científica. Además, los errores en identificación y los perfiles de multi-resistencia, raramente observados para otras especies de Candida, resultan en una difícil erradicación y fallas terapéuticas frecuentes en infecciones por C. auris. Presentamos el primer aislamiento de una cepa de C. auris en un hospital en Santiago, en un paciente proveniente de la India, que fue admitido para tratamiento de su pie diabético. La cepa fue recuperada de un cultivo de tejido e identificada por VITEK® 2 Compact. La identificación de C. auris fue confirmada por MALDI-TOF MS y secuenciación. El aislado fue resistente a fluconazol y susceptible a anfotericina y caspofungina, según puntos de corte recomendados por el CDC. La emergencia de C. auris es alarmante debido a que el modo de transmisión dentro del ambiente hospitalario no es claro y probablemente es multifactorial.

Candida auris is an emerging multi-drug-resistant fungus that is rapidly spreading worldwide. Since the first reports in 2009, many isolates across five continents have been identified as agents of hospital-associated infections. Independent and simultaneous outbreaks of C. auris are becoming a major concern for healthcare and scientific community. Moreover, laboratory misidentification and multi-drug-resistant profiles, rarely observed for other non-albicans Candida species, result in difficult eradication and frequent therapeutic failures of C. auris infections. In this article we present the first case of isolation of a strain of C. auris at a hospital in Santiago, in a patient coming from India, who was admitted for treatment of diabetic foot complications. The strain was recovered from a tissue culture and identified by VITEK® 2 Compact. The accurate identification of C. auris was confirmed by means of MALDI-TOF MS and DNA sequence analysis. The isolate was resistant to fluconazole, retaining only susceptibility to amphotericin and caspofungin with MIC breakpoints recommended by CDC. The emergence of C. auris is alarming because the mode of transmission within the healthcare environment is not clear and is likely to be multifactorial.

[First isolation de Candida auris in Chile]. / Primer aislamiento de Candida auris en Chile.

Candida auris is an emerging multi-drug-resistant fungus that is rapidly spreading worldwide. Since the first reports in 2009, many isolates across five continents have been identified as agents of hospital-associated infections. Independent and simultaneous outbreaks of C. auris are becoming a major concern for healthcare and scientific community. Moreover, laboratory misidentification and multi-drug-resistant profiles, rarely observed for other non-albicans Candida species, result in difficult eradication and frequent therapeutic failures of C. auris infections. In this article we present the first case of isolation of a strain of C. auris at a hospital in Santiago, in a patient coming from India, who was admitted for treatment of diabetic foot complications. The strain was recovered from a tissue culture and identified by VITEK® 2 Compact. The accurate identification of C. auris was confirmed by means of MALDI-TOF MS and DNA sequence analysis. The isolate was resistant to fluconazole, retaining only susceptibility to amphotericin and caspofungin with MIC breakpoints recommended by CDC. The emergence of C. auris is alarming because the mode of transmission within the healthcare environment is not clear and is likely to be multifactorial.

Directed random walk with random restarts: The Sisyphus random walk.

In this paper we consider a particular version of the random walk with restarts: random reset events which suddenly bring the system to the starting value. We analyze its relevant statistical properties, like the transition probability, and show how an equilibrium state appears. Formulas for the first-passage time, high-water marks, and other extreme statistics are also derived; we consider counting problems naturally associated with the system. Finally we indicate feasible generalizations useful for interpreting different physical effects.

La charla motivacional: una estrategia para abordar el desconocimiento de factores de riesgo ergonómico en un supermercado chileno / The motivational speech: a strategy to address the lack of unawareness ergonomic risk factors in a chilean supermarket

Los factores protectores y ergonómicos determinan la salud de la población trabajadora. Los factores de riesgo ergonómicos se enfocan a trastornos músculo-esqueléticos, lesiones músculo-esqueléticos, posturas forzadas, mala alimentación, obesidad y sedentarismo; y, los factores protectores se enfocan en promocionar estilos de vida saludables. Este proyecto se realizó utilizando la metodología de investigación de acción participativa. La muestra intencionada correspondió a 30 trabajadores de un supermercado de Santiago. El objetivo principal del estudio fue educar a través de charlas motivacionales sobre los factores ergonómicos y protectores. En el estudio se realizó una encuesta, previamente validad por expertos, para verificar el conocimiento y percepción de los participantes. Se descubrió que el 80% de los empleados tenía dolor físico; un 77%, estrés producto de su trabajo; un 30% de los trabajadores tenía el conocimiento de cómo adoptar una postura correcta antes de la realización de las charlas, percepción que aumentó a un 83% de conocimiento adquirido después de la realización de las charlas. Se logró apreciar una adecuada interacción entre las charlas motivacionales, la promoción de factores protectores y la información sobre riesgo ergonómico.

Protective and ergonomic factors determine the health of the working population. Ergonomic risk factors are focused on muscle-skeletal disorders, muscle-skeletal injuries, awkward postures, poor diet, obesity, sedentary and protective factors are focused on promoting healthy lifestyles. This project was conducted through participatory action research methodology. The sample consisted of 30 employees of a supermarket in Santiago. The main objective of the study was to educate through motivational talks on ergonomic and protective factors. The study used a survey, previously validated by experts to verify the knowledge and perception of the participants. It was found that 80% of employees had physical pain, stress 77% product of their work, 30% of workers had knowledge of what was correct posture before the completion of the talks, increased perception to 83% of knowledge gained after the completion of the talks. It was possible to appreciate a proper interaction between the motivational talks, promoting protective factors and ergonomic risk information.

Antigenemia y reacción de polimerasa en cadena en tiempo real en el diagnóstico de enfermedad por citomegalovirus en adultos con virus de inmunodeficiencia adquirida / Antigenemia and real time polymerase chain reaction for diagnosis of cytomegal ovirus disease in HIV infected adults

Background: Cytomegalovirus (CMV) infection is frequent in HIV adults. It is unknown usefulness of quantitative methods for diagnosing the CMV disease in Chilean patients. Aim: To determine the performance of antigenemia and real time polymerase chain reaction (rtPCR) in the diagnosis of CMV disease in Chilean HIV adults. Method: Detection of CMV by viral isolation (AVR), antigenemia and quantitative rtPCR in HIV adults. Results: The 102 adults with suspected CMV disease had lower LTCD4 count and higher HIV viral load than 77 patients without suspicion (p < 0.05). Antigenemia and PCR were positive in 47 (46.1%) and 37 (36.3%) adults with clinical suspicion and in 2 (2.6%) and 4 (5.2%) of 77 without suspicion. The sensitivity, specificity, positive and negative predictive value of antigenemia and RPCtr were 92%, 80%, 72% and 95% and 72%, 95%, 92% and 80%, respectively. The cutoff values were ≥ lcell (+) and ≥ 5.5 log10 copies/2 x 10(6) cells. CMV was isolated in 6/179 patients (3.4%), all symptomatic. Conclusión: Positivity of antigenemia and rtPCR are similar for diagnosing CMV disease in Chilean HIV adults. AVR is inappropriate as a gold standard for its low performance.

Introducción: La infección por citomegalovirus (CMV) es frecuente en adultos con virus de inmunodeficiencia humana (VIH). No se ha establecido la utilidad de los métodos cuantitativos para diagnosticar enfermedad por CMV en pacientes chilenos. Objetivo: Determinar la positividad de antigenemia y reacción de polimerasa en cadena en tiempo real (RPC-TR) en el diagnóstico de enfermedad por CMV en adultos chilenos con infección por VIH. Metodología: Se detectó CMV mediante aislamiento viral rápido (AVR), antigenemia y reacción de polimerasa en cadena en tiempo real (RPC-TR) cuantitativa en adultos infectados por VIH, con y sin sospecha de enfermedad por CMV. Resultados: El recuento de LT CD4 fue menor y mayor la carga de VIH en 102 sintomáticos respecto a 77 asintomáticos (p < 0,05). La antigenemia y la RPC-TR fueron positivas en 46 y 36% de los enfermos y en 3 y 5% de los asintomáticos respectivamente. La sensibilidad, especificidad, valor predictor positivo y negativo de la antigenemia y la RPC-TR fueron 92%, 80%, 72% y 95% y 72%, 95%, 92% y 80%, respectivamente. Los valores de corte fueron ≥ 1 núcleo (+) y ≥ 5,5 log10 copias/2 x 10(6) céls. Se aisló CMV en 3,4%, todos los sintomáticos. Conclusión: La antigenemia y la RPC-TR tienen una positividad similar para diagnosticar enfermedad por CMV en adultos chilenos con infección por VIH. El AVR es inapropiado como referencia por su baja positividad.

[Antigenemia and real time polymerase chain reaction for diagnosis of cytomegalovirus disease in HIV infected adults]. / Antigenemia y reacción de polimerasa en cadena en tiempo real en el diagnóstico de enfermedad por citomegalovirus en adultos con virus de inmunodeficiencia adquirida.

BACKGROUND: Cytomegalovirus (CMV) infection is frequent in HIV adults. It is unknown usefulness of quantitative methods for diagnosing the CMV disease in Chilean patients. AIM: To determine the performance of antigenemia and real time polymerase chain reaction (rtPCR) in the diagnosis of CMV disease in Chilean HIV adults. METHOD: Detection of CMV by viral isolation (AVR), antigenemia and quantitative rtPCR in HIV adults. RESULTS: The 102 adults with suspected CMV disease had lower LTCD4 count and higher HIV viral load than 77 patients without suspicion (p < 0.05). Antigenemia and PCR were positive in 47 (46.1%) and 37 (36.3%) adults with clinical suspicion and in 2 (2.6%) and 4 (5.2%) of 77 without suspicion. The sensitivity, specificity, positive and negative predictive value of antigenemia and RPCtr were 92%, 80%, 72% and 95% and 72%, 95%, 92% and 80%, respectively. The cutoff values were ≥ lcell (+) and ≥ 5.5 log10 copies/2 x 10(6) cells. CMV was isolated in 6/179 patients (3.4%), all symptomatic. CONCLUSION: Positivity of antigenemia and rtPCR are similar for diagnosing CMV disease in Chilean HIV adults. AVR is inappropriate as a gold standard for its low performance.

Valuation of endowment-insurance equity-linked contracts for stocks with exotic dynamics.

We consider the fair martingale prize of insurance contracts with benefit received either at the insurer's demise or at maturity. We show how to modify the dynamics of the underlying so as to incorporate the possibility that the traded stock has a strong support at some level. The resulting dynamics is integrated and the fair prize of several natural endowment-insurance contracts is obtained.

Monotonic continuous-time random walks with drift and stochastic reset events.

In this paper we consider a stochastic process that may experience random reset events which suddenly bring the system to the starting value and analyze the relevant statistical magnitudes. We focus our attention on monotonic continuous-time random walks with a constant drift: The process increases between the reset events, either by the effect of the random jumps, or by the action of the deterministic drift. As a result of all these combined factors interesting properties emerge, like the existence (for any drift strength) of a stationary transition probability density function, or the faculty of the model to reproduce power-law-like behavior. General formulas for two extreme statistics, the survival probability, and the mean exit time are also derived. To corroborate in an independent way the results of the paper, Monte Carlo methods were used. These numerical estimations are in full agreement with the analytical predictions.

Photovoltaic versus optical tweezers.

The operation of photovoltaic (PV) tweezers, using the evanescent light-induced PV fields to trap and pattern nano- and micro-meter particles on a LiNbO(3) crystal surface, is discussed. The case of a periodic light pattern is addressed in detail, including the role of particle shape and the modulation index of the light pattern. The use of a single Gaussian light beam is also considered. Illustrative experiments for the two situations are presented. The performance of such PV tweezers in comparison to the best established case of optical tweezers, using optical forces, is considered. Differential features between the two trapping approaches are remarked.

Exit times in non-Markovian drifting continuous-time random-walk processes.

By appealing to renewal theory we determine the equations that the mean exit time of a continuous-time random walk with drift satisfies both when the present coincides with a jump instant or when it does not. Particular attention is paid to the corrections ensuing from the non-Markovian nature of the process. We show that when drift and jumps have the same sign the relevant integral equations can be solved in closed form. The case when holding times have the classical Erlang distribution is considered in detail.

Digestibilidad de leguminosas y gramineas forrajeras en la alimentación de cuyes

Con el objetivo de determinar la digestibilidad en cuyes de los componentes nutritivos de la vicia villosa, trébol rojo y Lolium multiflorum en relación a la alfalfa, se evaluaron el coeficiente de digestibilidad de la fibra, proteína, materia seca, energía y consumo de materia seca en estas tres especies bajo un diseño de bloques completamente al azar con cuatro repeticiones. Los resultados mostraron para la alfalfa coeficientes de digestibilidad de 85.7

de la proteína de 2806.6 Kcal/kg de energía digestible, además de un valor económico de sustitución (V.E.S.) de la fibra, proteína y energía, de 0.41 y 0.38 $Us/Kg y0.009 $Us/1000 Kcal. respectivamente. El Lolium multiflorum tuvo la tendencia más alta para la digestibilidad de la fibra con 60.7

y el consumo más elevado con 81.3 g. Finalmente la materia seca tuvo una digestibilidad del 77.9

para el trébol rojo y de 75.6