Population stability: regulating size in the presence of an adversary

We introduce a new coordination problem in distributed computing that we call the population stability problem. A system of agents each with limited memory and communication, as well as the ability to replicate and self-destruct, is subjected to attacks by a worst-case adversary that can at a bounded rate (1) delete agents chosen arbitrarily and (2) insert additional agents with arbitrary initial state into the system. The goal is perpetually to maintain a population whose size is within a constant factor of the target size $N$. The problem is inspired by the ability of complex biological systems composed of a multitude of memory-limited individual cells to maintain a stable population size in an adverse environment. Such biological mechanisms allow organisms to heal after trauma or to recover from excessive cell proliferation caused by inflammation, disease, or normal development. We present a population stability protocol in a communication model that is a synchronous variant of the population model of Angluin et al. In each round, pairs of agents selected at random meet and exchange messages, where at least a constant fraction of agents is matched in each round. Our protocol uses three-bit messages and $\omega(\log^2 N)$ states per agent. We emphasize that our protocol can handle an adversary that can both insert and delete agents, a setting in which existing approximate counting techniques do not seem to apply. The protocol relies on a novel coloring strategy in which the population size is encoded in the variance of the distribution of colors. Individual agents can locally obtain a weak estimate of the population size by sampling from the distribution, and make individual decisions that robustly maintain a stable global population size

Comportamiento aerodinámico de barreras cortavientos 1

El trabajo presenta resultados de la exploración del campo de velocidades en estelas de distintos modelos de barreras porosas, con vistas a suposible utilización para proteger plantaciones o zonas habitadas de los efectos perniciosos del viento. Los ensayos se han hecho en túnel aerodinámico y, para las medidas, se ha utilizado un anemómetro de hilo caliente. Se ha medido: la velocidad media temporal, el nivel de turbulencia y, en algunos casos, el transporte turbulento y la inclinación del vector velocidad, en cuatro secciones distintas corriente abajo de cada barrera. El trabajo está dividido en ocho capítulos. En el primero se discute la posible utilidad de las barreras en agricultura. En el segundo se revisan ciertas características de las estelas turbulentas de diferentes obstáculos,con el fin de contrastar los resultados obtenidos con otros análogos. En el capítulo tercero se describen los métodos de medida. El cuarto presenta el grueso de los resultados, y los cuatro siguientes: la influencia del número de Reynolds, rugosidad del suelo, perfil del viento incidente y presencia de las paredes y techo del túnel, respectivamente. Los ensayos muestran que los perfiles de velocidades correspondientes a secciones situadas a cierta distancia de la barrera (mayor de seis a ocho veces la altura de ésta) se asemejan a los de un semichorro de baja velocidad que descarga paralelamente a una corriente más rápida. Los perfiles próximos y las condiciones iniciales del semichorro dependen de la configuración de la barrera. El modelo del semichorro equivalente permite calcular las características de la estela a distancias mayores que las que es posible reproducir en los experimentos. Por otra parte, sugiere ciertas modificaciones de la forma de la barrera para aumentar la longitud de la zona protegida del viento. La rugosidad del suelo y la existencia de perfiles de viento distintos del uniforme y más ajustados a la realidad, contribuyen a disminuir la longitud de la zona protegida. Esta observación está de acuerdo con los resultados de otros autores. Se observa que el nivel de turbulencia es muy sensible a las características geométricas de la barrera, lo que sugiere la posibilidad de controlar la capa límite sobre el terreno y, por tanto, el transporte de calor y masa en provecho de la productividad de cultivo. El trabajo que se presenta es parte de un programa más amplio, que tiene por objeto transmitir tecnología avanzada a ciertos dominios de interés para la agricultura y la industria

Notas corológicas del macrofitobentos de Andalucía (España). VIII

La flora de macroalgas marinas de Andalucía se recoge en los catálogos de Flores- Moya et al. (1995a, 1995b) y Conde et al. (1996a), y las adiciones posteriores de Conde et al. (1996b), Báez et al. (2001) y Altamirano et al. (2006, 2008). En este trabajo se presentan 9 citas nuevas para Andalucía (señaladas con un asterisco), 19 citas nuevas para la provincia de Huelva, 9 citas nuevas y una confirmación para la provincia de Málaga y 25 citas nuevas para la provincia de Granada. Mediante esta contribución el catálogo de Chlorophyceae de Andalucía consta de 90 taxones, mientras que los de Phaeophyceae y Rhodophyceae contienen 109 y 356 taxones, respectivamente. Todo el material recolectado se conservó en formol al 4% en agua de mar para su posterior determinación en el laboratorio. Como medio de montaje y preservación de las muestras microscópicas se ha utilizado sirope de maíz al 25% en agua destilada con unas gotas de formol al 4%. Los ejemplares identificados se han depositado en el herbario de la Universidad de Málaga (MGC Phyc). Para la ordenación taxonómica se ha seguido a Guiry & Guiry (2009

Regions of interest computed by SVM wrapped method for Alzheimer’s disease examination from segmented MRI

Accurate identification of the most relevant brain regions linked to Alzheimer’s disease (AD) is crucial in order to improve diagnosis techniques and to better understand this neurodegenerative process. For this purpose, statistical classification is suitable. In this work, a novel method based on support vector machine recursive feature elimination (SVM-RFE) is proposed to be applied on segmented brain MRI for detecting the most discriminant AD regions of interest (ROIs). The analyses are performed both on gray and white matter tissues, achieving up to 100% accuracy after classification and outperforming the results obtained by the standard t-test feature selection. The present method, applied on different subject sets, permits automatically determining high-resolution areas surrounding the hippocampal area without needing to divide the brain images according to any common template.This work was partly supported by the MICINN under the TEC2012-34306 project and the Consejería de Innovación, Ciencia y Empresa (Junta de Andalucía, Spain) under the Excellence Projects P09-TIC-4530 and P11-TIC-7103. Data collection and sharing for this project was funded by the Alzheimer’s Disease Neuroimaging Initiative (ADNI; National Institutes of Health Grant U01 AG024904).This research was also supported by NIH grants P30 AG010129, K01 AG030514, and the Dana Foundation

Furrow and Ridge Soil Nitrogen Mineralization in a Surface Irrigated Artichoke Field

[EN] Quantitative knowledge of soil organic nitrogen net mineralization (NNM) in field conditions is crucial to optimize N fertilization of crops. In a field fertilization trial of artichokes 48 PE tubes were inserted to 20 cm depth in the soil in plant row and irrigation furrows and soil samples were periodically taken during two and a half months to determine NNM. A parallel essay with disturbed samples from the same procedence was carried out in the laboratory at 25ºC and 10 kPa soil water tension. Soil sample position (ridge and furrow) did not significantly determined NNM in the laboratory essay. Although NNM (obtained from laboratory incubation and corrected to field soil temperature and moisture monitored during the experimental period) overpredicted measured field NNM, matching of both was better than those reported in other studies. NNM rate for the 76 days period of incubation predicted from lab data was 22.9 kg N/ ha x 0.1 m while corresponding field values corrected by Br- or Cl- mass balance were 10% and 20% lower respectively in ridge position and under 40% lower by either method in furrow position.The research reported in this paper was supported by a fund from CICYT-INIA (project RTA01-117-C2-2)Lidón, A.; Bautista, I.; De La Iglesia, F.; Oliver Talens, J.; Llorca, R.; Cruz-Romero, G. (2006). Furrow and Ridge Soil Nitrogen Mineralization in a Surface Irrigated Artichoke Field. Acta Horticulturae. (700):71-74. https://doi.org/10.17660/ActaHortic.2006.700.7S717470

Relation of resistin levels with cardiovascular risk factors, insulin resistance and inflammation in naı¨ve diabetes obese patients

Producción CientíficaBackground: The aim of the present study was to explore the relationship of resistin levels with cardiovascular risk factors, insulin resistance and inflammation in naı¨ve diabetic patients. Subjects: A population of 66 naı¨ve diabetic patients with obesity was analyzed. A complete nutritional and biochemical evaluation was performed. Results: The mean age 56.9 11.6 years and the mean BMI was 37.8 6.3. Patients were divided in two groups by median resistin value (3.3 ng/ml), group I (patients with the low values, average value 2.5 0.5) and group II (patients with the high values, average value 4.8 1.8). Patients in the group I had lower waist circumference, total cholesterol, LDLcholesterol and C-reactive protein than patients in group II. Correlation analysis showed a significant correlation among resistin levels and the independent variables; BMI (r = 0.26; p < 0.05), waist circumference (r = 0.38; p < 0.05), fat mass (r = 0.28; p < 0.05), LDL-cholesterol (r = 0.3; p < 0.05), C-reactive protein (r = 0.28; p < 0.05). In the multivariate analysis, resistin concentration increase 0.024 ng/ml (CI 95%: 0.006–0.42) for each mg/dl of C-reactive protein. Conclusion: Circulating resistins are associated with C-reactive protein in an independent way in naı¨ve diabetic patients

The adrenal medulla modulates mechanical allodynia in a rat model of neuropathic pain

We have investigated whether the stress response mediated by the adrenal medulla in rats subjected to chronic constriction injury of the sciatic nerve (CCI) modulates their nocifensive behavior. Treatment with SK29661 (300 mg/kg; intraperitoneal (I.P.)), a selective inhibitor of phenylethanolamine N-methyltransferase (PNMT) that converts noradrenaline (NA) into adrenaline (A), fully reverted mechanical allodynia in the injured hind paw without affecting mechanical sensitivity in the contralateral paw. The effect was fast and reversible and was associated with a decrease in the A to NA ratio (A/NA) in the adrenal gland and circulating blood, an A/NA that was elevated by CCI. 1,2,3,4-tetrahydroisoquinoline-7-sulfonamide (SKF29661) did not a ect exocytosis evoked by Ca2+ entry as well as major ionic conductances (voltage-gated Na+, Ca2+, and K+ channels, nicotinic acetylcholine receptors) involved in stimulus-secretion coupling in chroma n cells, suggesting that it acted by changing the relative content of the two adrenal catecholamines. Denervation of the adrenal medulla by surgical splanchnectomy attenuated mechanical allodynia in neuropathic animals, hence confirming the involvement of the adrenal medulla in the pathophysiology of the CCI model. Inhibition of PNMT appears to be an effective and probably safe way to modulate adrenal medulla activity and, in turn, to alleviate pain secondary to the injury of a peripheral nerveThis research was funded by the SPANISH MINISTER OF SCIENCE AND INNOVATION, grants BFU2011-26253, BFU2015-70067-REDC to A.R.A., and SAF2016-78892 to A.G.G, and by UNIVERSIDAD COMPLUTENSE DE MADRID, grant PR75/18-21593 to A.R.A