BOOTSTRAPPING IN VECTOR AUTOREGRESSIONS: AN APPLICATION TO THE PORK SECTOR

Standard bootstrap method is used to generate confidence intervals (CIs) of impulse response functions of VAR and SVAR models in the pork sector. In the VAR model, the bootstrap method does not produce significant different results from Monte Carlo simulations. In the SVAR analysis, on the other hand, the bootstrap CIs are significantly different from Monte Carlo CIs after a six period forecast intervals. This suggests that the choice of method used to measure reliability of IRFs is not trivial. Furthermore, bootstrap CIs in SVAR model seem to be more stable than MC CIs, which tend to be wider in the longer horizons.Research Methods/ Statistical Methods,

Two Stages in the evolution of binary alkali Bose-Einstein condensate mixtures towards phase segregation

Two stages of quantum spinodal decomposition is proposed and analyzed for this highly non-equilibrium process. Both time and spatial scales for the process are found. Qualitative agreement with existing data is found. Some cases the agreements are quantitative. Further experimental verifications are indicated.Comment: late

A search for pre- and proto-brown dwarfs in the dark cloud Barnard 30 with ALMA

In this work we present ALMA continuum observations at 880 $\mu$m of 30 sub-mm cores previously identified with APEX/LABOCA at 870$\mu$m in the Barnard 30 cloud. The main goal is to characterize the youngest and lowest mass population in the cloud. As a result, we report the detection of five (out of 30) spatially unresolved sources with ALMA, with estimated masses between 0.9 and 67 M$_{\rm Jup}$. From these five sources, only two show gas emission. The analysis of multi-wavelength photometry from these two objects, namely B30-LB14 and B30-LB19, is consistent with one Class II- and one Class I low-mass stellar object, respectively. The gas emission is consistent with a rotating disk in the case of B30-LB14, and with an oblate rotating envelope with infall signatures in the case of LB19. The remaining three ALMA detections do not have infrared counterparts and can be classified as either deeply embedded objects or as starless cores if B30 members. In the former case, two of them (LB08 and LB31) show internal luminosity upper limits consistent with Very Low Luminosity objects, while we do not have enough information for LB10. In the starless core scenario, and taking into account the estimated masses from ALMA and the APEX/LABOCA cores, we estimate final masses for the central objects in the substellar domain, so they could be classified as pre-BD core candidates.Comment: Published in A&

Consumo de drogas adictivas en alumnos de la UNCuyo, Mendoza, Argentina.

Este trabajo muestra los resultados de una encuesta realizada en 2010 sobre consumo de drogas adictivas en alumnos de 7 Facultades de la UNCUYO y los compara con los resultados obtenidos 12 años antes con una encuesta equivalente. La encuesta fue semiestructurada, con 17 preguntas, autocumplimentada, individual y anónima, con una muestra de 1108 alumnos de ambos sexos. De esa encuesta se utilizaron 7 preguntas específicas sobre drogas adictivas y una pregunta sobre consumo de medicamentos en general, con 46 opciones entre las que figuraban 10 denominaciones comerciales de benzodiacepinas, como drogas adictivas de prescripción. Para las comparaciones estadísticas se utilizó Chi cuadrado. El ranking de drogas utilizadas fue relativamente similar en 1998 y 2010 pero, exceptuando tabaco y “otras drogas" que se mantuvieron estables, el resto aumentó alrededor de 4 veces en el periodo. El 82,8% de los alumnos manifestó consumir alcohol (siempre + a veces); de 1 a 5 vasos semanales el 79%. En todas las Facultades, cerveza y Fernet encabezaron el ranquing de preferencias por bebidas alcohólicas. La prevalencia del consumo de tabaco en el total de la muestra se mantuvo constante en 1998 y 2010 (alrededor del 28%) pero el consumo entre Facultades fue variable y en Artes fue significativamente más elevado (42%). Siguen en el ranking marihuana con 10% de prevalencia, tranquilizantes con alrededor del 6% y cocaína con poco más del 1%. Finalmente “otras drogas" (Hachis, LSD, extasis, anabólicos, anfetaminas, “hongos") representaron solamente un 3% de prevalencia. Artes y Ciencias Políticas mostraron las mayores prevalencias de consumo y Derecho e Ingeniería las menores. Esto indica implementar acciones preventivas y correctivas particulares para cada Facultad.This is a research on addictive drugs use by students of 7 schools of the UNCUYO. The results of an inquire made in 2010 are compared with the results of an equivalent inquire made 12 years before. The inquire was partially structured and consists of 17 questions, autographic, individual and anonymous, and was applied to a 1108 students sample. The inquire was devoted to ascertain use and knowledge about prescription drugs use and comprised 7 specific questions on addictive drugs use as well as a prescription drugs question with 46 options comprising 10 commercial names of benzodiazepines as addictive prescription drugs. Chi square was used for statistic comparisons. The ranking of addictive drugs use was quite similar in the 1998 and the 2010 inquires. However, excepting tobacco and “other drugs" which prevalence remained constant, the rest of consigned drugs prevalence increased about 4 folds in this period. The prevalence of alcohol users was about 83% (always + some-times users) and 79% said to drank 1 to 5 glasses a week. Bear and Fernet headed the ranking of alcoholic drinks preference. The prevalence of tobacco use in the whole student sample was constant in both inquires (about 28%) but the amongschools use was variable; in Arts was significantly higher than that (42%). Followed in the ranking marihuana with a 10% prevalence, tranquilizers (about 6%) and cocaine with a little more than 1%. Finally, “other drugs" (Hachis, LSD, extasis, anabolics, anfetamines and funguses) represented all together a 3% prevalence. Arts and Politic Sciences Schools showed the highest prevalence in addictive drugs use and Law and Engineery the lowest. The results point to planning particular preventing and corrective actions for each School.Fil: Kaiser, L. D.. Universidad Nacional de Cuyo. Facultad de Ciencias Médicas. Área Farmacología.Fil: Rodríguez, C.. Universidad Nacional de Cuyo. Facultad de Ciencias Médicas. Área Farmacología.Fil: Zapata, M. P.. Universidad Nacional de Cuyo. Facultad de Ciencias Médicas. Área Farmacología.Fil: Sacchi, O. J.. Universidad Nacional de Cuyo. Facultad de Ciencias Médicas. Área Farmacología.Fil: Riestra, E. C.. Universidad Nacional de Cuyo. Facultad de Ciencias Médicas. Área Farmacología.Fil: Aranda, L.. Universidad Nacional de Cuyo. Facultad de Ciencias Médicas. Área Farmacología.Fil: Rodríguez Echandía, Eduardo. Universidad Nacional de Cuyo. Facultad de Ciencias Médicas. Área Farmacología

Voltage rectification by a SQUID ratchet

We argue that the phase across an asymmetric dc SQUID threaded by a magnetic flux can experience an effective ratchet (periodic and asymmetric) potential. Under an external ac current, a rocking ratchet mechanism operates whereby one sign of the time derivative of the phase is favored. We show that there exists a range of parameters in which a fixed sign (and, in a narrower range, even a fixed value) of the average voltage across the ring occurs, regardless of the sign of the external current dc component.Comment: 4 pages, 4 EPS figures, uses psfig.sty. Revised version, to appear in Physical Review Letters (26 August 1996

On the parallelization of molecular dynamics codes

Abstract Molecular dynamics (MD) codes present a high degree of spatial data locality and a significant amount of independent computations. However, most of the parallelization strategies are usually based on the manual transformation of sequential programs either by completely rewriting the code with message passing routines or using specific libraries intended for writing new MD programs. In this paper we propose a new library-based approach (DDLY) which supports parallelization of existing short-range MD sequential codes. The novelty of this approach is that it can directly handle the distribution of common data structures used in MD codes to represent data (arrays, Verlet lists, link cells), using domain decomposition. Thus, the insertion of run-time support for distribution and communication in a MD program does not imply significant changes to its structure. The method is simple, efficient and portable. It may be also used to extend existing parallel programming languages, such as HPF

Aplicación de la clasificación ATC al análisis de las prescripciones en DAMSU : I : los grupos de medicamentos que encabezan el ranking

Este es un estudio sobre utilización de medicamentos donde se analiza la evolución de la prescripción, en DAMSU de UNCuyo, de los 14 grupos terapéuticos (GT) de la clasificación ATC, durante 4 años consecutivos. Su objetivo fue determinar la prevalencia de las prescripciones en los 3 primeros niveles de la clasificación. Los datos fueron recolectados en los meses de abril, junio, setiembre y diciembre utilizando la metodología del DURG y procesados con un programa EPI INFO. Las comparaciones estadísticas fueron realizadas mediante la Prueba no paramétrica de los Signos. El ranking de GT fue constante pero el total de prescripciones disminuyó significativamente entre 2004 y 2007. Los GT del 1º nivel: S. Nervioso (N), S. cardiovascular (C), Digestivo y Metabolismo (A) y Músculo-esquelético (M), ocuparon, en orden decreciente, los cuatro primeros puestos del ranking durante los 4 años. De estos GT fueron analizados los subgrupos del 2º y 3º nivel. La prescripción de Psicolépticos + Psicoanalépticos superó a la de Analgésicos en el grupo N. En el grupo C los Agentes Antihipertensivos, y entre ellos los IECAs, encabezaron el ranking. Las vitaminas fueron las primeras en el GT A y el subgrupo de Antiinflamatorios y Antirreumáticos en el GT M. Se discuten estos resultados en función de la racionalidad de las prescripciones.This is a drug utilization research on the evolution of drug prescription in DAMSU of UNCuyo, during 4 consecutive years, comprising the 14 therapeutic groups (TG) of the ATC classification. The object was to determine the prescription prevalence in the 3 first levels of this classification. Data from April, June, September and December were collected according to the DURG methodology and processed by an EPI INFO program. Statistic comparisons were done with the nonparametric Signs Test. The TG ranking was constant but the total drug prescription lowered significantly between 2004 and 2007. Four TG at the first level were: Nervous S. (N), Cardiovascular S. (C), Digestive and Metabolism (A) and Muscle-Squeletal (M) shared in a decreasing order the first 4 places of the ranking in the 4 scored years. From these TG the 2º and 3º subgroups were analyzed. In the TG N the prescription of psychodrugs (Psycholeptics + Psychoanaleptics) was higher than that of Analgesics. In the TG C the Antihipertensive Agents, among which the ACEIs drugs are, did head the ranking. Vitamins were the first in the TG A and the subgroup of Anti-inflammatory and Antirheumatics headed the TG M. Results are discussed in terms of rationality of prescriptions.Fil: Sacchi, O. J.. Universidad Nacional de Cuyo. Facultad de Ciencias Médicas. Departamento de PatologíaFil: Kaiser, L. D.. Universidad Nacional de Cuyo. Facultad de Ciencias Médicas. Departamento de PatologíaFil: Riestra, E. C.. Universidad Nacional de Cuyo. Facultad de Ciencias Médicas. Departamento de PatologíaFil: Rodríguez, C. I.. Universidad Nacional de Cuyo. Facultad de Ciencias Médicas. Departamento de PatologíaFil: Zapata, M. P.. Universidad Nacional de Cuyo. Facultad de Ciencias Médicas. Departamento de PatologíaFil: Rodríguez Echandía, Eduardo. Universidad Nacional de Cuyo. Facultad de Ciencias Médicas. Departamento de Patologí

Dissipation Enhanced Asymmetric Transport in Quantum Ratchets

Quantum mechanical motion of a particle in a periodic asymmetric potential is studied theoretically at zero temperature. It is shown based on semi-classical approximation that the tunneling probability from one local minimum to the next becomes asymmetric in the presence of weak oscillating field, even though there is no macroscopic field gradient in average. Dissipation enhances this asymmetry, and leads to a steady unidirectional current, resulting in a quantum ratchet system.Comment: 12 pages, 2 Figures, submitted to J. Phys. Soc. Jp