Rare Transition Events in Nonequilibrium Systems with State-Dependent Noise: Application to Stochastic Current Switching in Semiconductor Superlattices

Using recent mathematical advances, a geometric approach to rare noise-driven transition events in nonequilibrium systems is given, and an algorithm for computing the maximum likelihood transition curve is generalized to the case of state-dependent noise. It is applied to a model of electronic transport in semiconductor superlattices to investigate transitions between metastable electric field distributions. When the applied voltage $V$ is varied near a saddle-node bifurcation at $V_th$, the mean life time $$ of the initial metastable state is shown to scale like $log \propto |V_th - V|^{3/2}$ as $V\to V_th$

Aspects of the behavioral and endocrine ontogeny of six moustached tamarins, Saguinus mystax (Callitrichinae)

Deutsche Forschungsgemeinschaft (HE 1870/10-1,2

INTRODUCCIÓN Y MANEJO DE PRIMATES EN ISLAS DE LA AMAZONÍA PERUANA - CONSIDERACIONES DE UN POTENCIAL PROBLEMA

This note discusses potential consequences of merging Isla Muyuy on the river Amazon which hosts an introduced (allochthonous) population of red-bellied tamarins, Saguinus labiatus (Callitrichidae), with the mainland, due to the Amazon’s riverine dynamics. It is recommended that an action plan be developed for this case, in order to avoid negative consequences for native populations of other species of tamarins and the ecosystem, in case Isla Muyuy joins the mainland.En esta nota se discuten las potenciales consecuencias de una fusión de la Isla Muyuy con la tierra firme, debido a la dinámica fluvial del río Amazonas. La isla alberga una población introducida (alóctona) del pichico de pecho anaranjado, Saguinus labiatus (Callitrichidae). Se recomienda desarrollar un plan de acción, a fin de evitar consecuencias negativas para poblaciones autóctonas de otras especies de pichicos y del ecosistema, en caso que la Isla Muyuy se una con la tierra firme

Correlates of genetic monogamy in socially monogamous mammals: insights from Azara's owl monkeys

Understanding the evolution of mating systems, a central topic in evolutionary biology for more than 50 years, requires examining the genetic consequences of mating and the relationships between social systems and mating systems. Among pair-living mammals, where genetic monogamy is extremely rare, the extent of extra-group paternity rates has been associated withmale participation in infant care, strength of the pair bond and length of the breeding season. This study evaluated the relationship between two of those factors and the genetic mating system of socially monogamous mammals, testing predictions that male care and strength of pair bond would be negatively correlated with rates of extra-pair paternity (EPP). Autosomal microsatellite analyses provide evidence for genetic monogamy in a pair-living primate with bi-parental care, the Azara’s owl monkey (Aotus azarae). A phylogenetically corrected generalized least square analysis was used to relate male care and strength of the pair bond to their genetic mating system (i.e. proportions of EPP) in 15 socially monogamous mammalian species. The intensity of male care was correlated with EPP rates in mammals, while strength of pair bond failed to reach statistical significance. Our analyses showthat, once social monogamy has evolved, paternal care, and potentially also close bonds, may facilitate the evolution of genetic monogamy.German Science Foundation (HU 1746/2-1); Wenner-Gren Foundation; L.S.B. Leakey Foundation;National Geographic Society; National Science Foundation (BCS-0621020, 1219368, and 1232349); the University of Pennsylvania Research Foundation; the Zoological Society of San Dieg

Determinants of Length of Stay After Vaginal Deliveries in the Friuli Venezia Giulia Region (NorthEastern Italy), 2005\u20132015

Although length of stay (LoS) after childbirth has been diminishing in several high-income countries in recent decades, the evidence on the impact of early discharge (ED) on healthy mothers and term newborns after vaginal deliveries (VD) is still inconclusive and little is known on the characteristics of those discharged early. We conducted a population-based study in Friuli Venezia Giulia (FVG) during 2005\u20132015, to investigate the mean LoS and the percentage of LoS longer than our proposed ED benchmarks following VD: 2 days after spontaneous vaginal deliveries (SVD) and 3 days post instrumental vaginal deliveries (IVD). We employed a multivariable logistic as well as a linear regression model, adjusting for a considerable number of factors pertaining to health-care setting and timeframe, maternal health factors, newborn clinical factors, obstetric history factors, socio-demographic background and present obstetric conditions. Results were expressed as odds ratios (OR) and regression coefcients (RC) with 95% confdence interval (95%CI). The adjusted mean LoS was calculated by level of pregnancy risk (high vs. low). Due to a very high number of multiple tests performed we employed the procedure proposed by Benjamini-Hochberg (BH) as a further selection criterion to calculate the BH p-value for the respective estimates. During 2005\u20132015, the average LoS in FVG was 2.9 and 3.3 days after SVD and IVD respectively, and the pooled regional proportion of LoS>ED was 64.4% for SVD and 32.0% for IVD. The variation of LoS across calendar years was marginal for both vaginal delivery modes (VDM). The adjusted mean LoS was higher in IVD than SVD, and although a decline of LoS>\u2009ED and mean LoS over time was observed for both VDM, there was little variation of the adjusted mean LoS by nationality of the woman and by level of pregnancy risk (high vs. low). By contrast, the adjusted fgures for hospitals with shortest (centres A and G) and longest (centre B) mean LoS were 2.3 and 3.4 days respectively, among \u201clow risk\u201d pregnancies. The corresponding fgures for \u201chigh risk\u201d pregnancies were 2.5 days for centre A/G and 3.6 days for centre B. Therefore, the shift from \u201clow\u201d to \u201chigh\u201d risk pregnancies in all three latter centres (A, B and G) increased the mean adjusted LoS just by 0.2 days. By contrast, the discrepancy between maternity centres with highest and lowest adjusted mean LoS post SVD (hospital B vs. A/G) was 1.1 days both among \u201clow risk\u201d (1.1 = 3.4\u20132.3 days) and \u201chigh risk\u201d (1.1 = 3.6\u20132.5) pregnanices. Similar patterns were obseved also for IVD. Our adjusted regression models confrmed that maternity centres were the main explanatory factor for LoS after childbirth in both VDM. Therefore, health and clinical factors were less infuential than practice patterns in determining LoS after VD. Hospitalization and discharge policies following childbirth in FVG should follow standardized guidelines, to be enforced at hospital level. Any prolonged LoS post VD (LoS>\u2009ED) should be reviewed and audited if need be. Primary care services within the catchment areas of the maternity centres of FVG should be improved to implement the follow up of puerperae undergoing ED after VD. At the beginning of the 20th century home births were the norm and hospital deliveries very rare. Women started to deliver in hospital during World War 2 (WW2), in facilities near the military areas where their respective partners were training. Tis trend continued in the decades following WW2, with standard length of stay afer childbirth (LoS) increasing up to 10 days. In the 70 ies some USA hospitals started to assess the health of mothers and newborn for eligibility to returnhome within 12\u201324 hours afer childbirth, with a midwife on call for domiciliary care up to 3 days for 2 weekspost discharge. In 1992 the American Academy of Pediatrics (AAP) and the American College of Obstetricians and Gynecologists (ACOG) formalized the most frequently shared defnition of early discharge (ED) afer childbirth worldwide as a LoS less than 48 h post spontaneous vaginal deliveries (SVD) and less than 96 h post cesarean section (CS). Tereafer the reduction of LoS expanded to other high-income countries, with increasing applications of ED. LoS afer childbirth remained however a controversial aspect of obstetric care, creating an open debate not only on its impact on the health of mothers and babies but also on health policies, state legislations and functioning of the respective health care systems. Nevertheless, ED of mothers and newborn has in fact increased dramatically in several high-income countries over the past 10\u201315 years. However, the evidence on the impact of ED on healthy mothers and term newborns ( 6537 weeks) afer a vaginal delivery (VD) is still inconclusive and little is known of the characteristics of those discharged early. Since LoS has become a critical indicator of efciency of health care delivery, understanding its associated factors could provide information helpful in the reduction of health care costs, improvement in the delivery of obstetric care, containment of untoward events associated with comorbidities and complications requiring readmission. For instance, in Canada (excluding Quebec) from 2003 to 2010, neonatal readmission rates were lowest for LoS of 1\u20132 days following VD and 2\u20134 days afer CS. Several factors are reportedly associated with LoS in the open literature, including readiness for discharge (clinical and perceived) of the mother8,17\u201319. However, information on the impact of medical/obstetrical conditions associated with pregnancies is scarce or totally lacking. Using a comprehensive database with information on a considerable number of factors, we previously reviewed the case mix of hospital performance by LoS post SVD as well as instrumental vaginal deliveries (IVD) during 2005\u20132015 in Friuli Venezia Giulia (FVG), a region of North-Eastern Italy. In this study we present the impact of the outstanding determinants on LoS following SVD and IVD, with the aim of inforing health care policy makers

Unstable Attractors: Existence and Robustness in Networks of Oscillators With Delayed Pulse Coupling

We consider unstable attractors; Milnor attractors $A$ such that, for some neighbourhood $U$ of $A$, almost all initial conditions leave $U$. Previous research strongly suggests that unstable attractors exist and even occur robustly (i.e. for open sets of parameter values) in a system modelling biological phenomena, namely in globally coupled oscillators with delayed pulse interactions. In the first part of this paper we give a rigorous definition of unstable attractors for general dynamical systems. We classify unstable attractors into two types, depending on whether or not there is a neighbourhood of the attractor that intersects the basin in a set of positive measure. We give examples of both types of unstable attractor; these examples have non-invertible dynamics that collapse certain open sets onto stable manifolds of saddle orbits. In the second part we give the first rigorous demonstration of existence and robust occurrence of unstable attractors in a network of oscillators with delayed pulse coupling. Although such systems are technically hybrid systems of delay differential equations with discontinuous `firing' events, we show that their dynamics reduces to a finite dimensional hybrid system system after a finite time and hence we can discuss Milnor attractors for this reduced finite dimensional system. We prove that for an open set of phase resetting functions there are saddle periodic orbits that are unstable attractors.Comment: 29 pages, 8 figures,submitted to Nonlinearit

EXPLORACIONES PRIMATOLOGICAS EN LAS QUEBRA DAS BLANCO, BLANQUILLO Y TANGARANA (RIO TAHUAYO, AMAZONIA PERUANA

Reportamos los resultados de una exploración primatológica en la Reserva Comunal Tamshiyacu-Tahuayo (RCTT) y sus cercanías, con énfasis al estado actual de la fauna primatológica en general incluyendo al huapo rojo, Cacajao calvus ucayalii, y la presencia de asociaciones interespecíticas entre Saguinus fuscicollis y Saguinus mystax. De las especies que habitan en la RCTT, las dos especies de pichicos fueron observadas con mayor frecuencia, de otros primates de tamaño pequeño y mediano como Callicebus cupreus (tocón colorado), Saimiri sciureus (fraile) y Pithecia monachus (huapo negro). Otros de tamaño mediano y grande fueron raras veces observados o ni una vez. Entre los primates, los de tamaño grande y mediano están sujetos a una alta presión de caza que podría llevarlos a una inminente extinción en esta zona

Estación Biológica Quebrada Blanco: Un sitio poco conocido para investigación en biodiversidad y ecología en la Amazonía peruana

The Estación Biológica Quebrada Blanco (EBQB) in north-eastern Peruvian Amazonia is a place where research has been conducted since 1984; mainly, on the ecology and behavior of primates, but, later inventories were realized for trees (>10 cm dbh), ferns and birds. The EBQB area is very little disturbed and located in a region of high biodiversity. Here we describe the history of EBQB, summarize the available information on its biodiversity and point out the potential of EBQB for future studies on the biodiversity and ecology of a broad spectrum of organisms.La Estación Biológica Quebrada Blanco (EBQB), en el nororiente de la Amazonía peruana, es un lugar donde se ha venido realizando investigación científica desde 1984. En sus inicios la investigación se enfocaba en la ecología y el comportamiento de primates; sin embargo, también se suman trabajos sobre inventarios de algunos grupos de árboles (>10 cm DAP), helechos y aves. El área de la EBQB es muy poco perturbada y está ubicada en una zona de alta biodiversidad. En este trabajo resumimos su historia, la información sobre biodiversidad de que se dispone y mostramos a la EBQB como un lugar con alto potencial para futuros estudios en biodiversidad y ecología en un amplio espectro de organismos