On the influence of statistics on the determination of the mean value of the depth of shower maximum for ultra high energy cosmic ray showers

The chemical composition of ultra high energy cosmic rays is still uncertain. The latest results obtained by the Pierre Auger Observatory and the HiRes Collaboration, concerning the measurement of the mean value and the fluctuations of the atmospheric depth at which the showers reach the maximum development, Xmax, are inconsistent. From comparison with air shower simulations it can be seen that, while the Auger data may be interpreted as a gradual transition to heavy nuclei for energies larger than ~ 2-3x10^18 eV, the HiRes data are consistent with a composition dominated by protons. In Ref. [1] it is suggested that a possible explanation of the observed deviation of the mean value of Xmax from the proton expectation, observed by Auger, could originate in a statistical bias arising from the approximated exponential shape of the Xmax distribution, combined with the decrease of the number of events as a function of primary energy. In this paper we consider a better description of the Xmax distribution and show that the possible bias in the Auger data is at least one order of magnitude smaller than the one obtained when assuming an exponential distribution. Therefore, we conclude that the deviation of the Auger data from the proton expectation is unlikely explained by such statistical effect.Comment: To be published in Journal of Physics G: Nuclear and Particle Physic

Capillary rise of a liquid between two vertical plates making a small angle.

The penetration of a wetting liquid in the narrow gap between two vertical plates making a small angle is analyzed in the framework of the lubrication approximation. At the beginning of the process, the liquid rises independently at different distances from the line of intersection of the plates except in a small region around this line where the effect of the gravity is negligible. The maximum height of the liquid initially increases as the cubic root of time and is attained at a point that reaches the line of intersection only after a certain time. At later times, the motion of the liquid is confined to a thin layer around the line of intersection whose height increases as the cubic root of time and whose thickness decreases as the inverse of the cubic root of time. The evolution of the liquid surface is computed numerically and compared with the results of a simple experiment

The potential of Λ and Ξ− studies with PANDA at FAIR

The antiproton experiment PANDA at FAIR is designed to bring hadron physics to a new level in terms of scope, precision and accuracy. In this work, its unique capability for studies of hyperons is outlined. We discuss ground-state hyperons as diagnostic tools to study non-perturbative aspects of the strong interaction, and fundamental symmetries. New simulation studies have been carried out for two benchmark hyperon-antihyperon production channels: p¯p→Λ¯Λ and p¯p→Ξ¯+Ξ−. The results, presented in detail in this paper, show that hyperon-antihyperon pairs from these reactions can be exclusively reconstructed with high efficiency and very low background contamination. In addition, the polarisation and spin correlations have been studied, exploiting the weak, self-analysing decay of hyperons and antihyperons. Two independent approaches to the finite efficiency have been applied and evaluated: one standard multidimensional efficiency correction approach, and one efficiency independent approach. The applicability of the latter was thoroughly evaluated for all channels, beam momenta and observables. The standard method yields good results in all cases, and shows that spin observables can be studied with high precision and accuracy already in the first phase of data taking with PANDA

Qualidade das silagens de leucena (Leucaena leucocephala) e gliricídia (Gliricídia sepium) sob diferentes épocas de abertura dos silos.

Avaliou-se silagens de Leucena (Leucaena leucocephala) e Gliricídia (Gliricídia sepium), produzidas em tubos de PVC, com 7, 14, 28 e 56 dias de fermentação, determinando-se os valores de matéria seca (MS), proteína bruta (PB), fibra em de tergente neutro (FDN), fibra em detergente ácido (FDA), extrato etéreo (EE), carboidratos não estruturais (CNE), digestibilidade in vitro da matéria seca (DIVMS) e pH. Os teores médios de MS, PB, FDN, FDA, DIVMS, pH e CNE apresentaram diferenças significativas entre as espécies forrageiras, não diferindo em relação ao teor de EE. Houve diferenças significativas para todos os parâmetros avaliados, exceto a MS, quando avaliados em função do tempo de incubação. As silagens de leucena e gliricídia apresentaram teores médios de MS (28,24 e 28,20%, respectivamente) inferiores a faixa recomendada como requisitos para a confecção de uma boa silagem. As silagens em estudo apresentaram altos níveis de PB, no entanto apresentaram baixa digestibilidade. Os valores de pH para ambas silagens foram elevados em todos os tempos de incubação, o que pode prejudicar o processo fermentativo

Efectividad de la miotomía de aductores y tenotomía de psoasiliaco en la prevención de la luxación de cadera en la parálisis cerebral espástica

Se evaluaron 208 pacientes con parálisis cerebral infantil espástica, sin retardo mental, con potencia de marcha; la edad osciló entre los 16 meses y los 13 años de edad con un promedio de 5 años. El seguimiento fue de la 10 años, con promedio de 6,2 años. A los que se realizó miotomía de aductores y tenotomía del psoasiliaco. Los resultados fueron valorados con el índice de migración lateral. Los mejores resultados se logran en niños de 2 años con 8 5% de caderas reducidas.We rewiewd 208 spastic cerebral palsied patients, without mental ratardation and with gait potential. They were 16 months to 13 years old (average 5 years). Follow-up was 1 to 10 years (average: 6,2 years). Myotomy were evaluated by lateral migration index. Best results were obteined in children of 2 years with 85% of reducted hips

Catálogo de los briófitos epífitos que crecen en bosques de quercíneas del cuadrante noroccidental ibérico

[ES] En las últimas décadas se han producido importantes avances en el conocimiento de la brioflora ibérica. Gracias a ello se puede decir que hoy día la flora muscinal ibérica se conoce relativamente bien a nivel taxonómico. Sin embargo, en cuanto a las distribuciones de las especies aún queda mucho trabajo por hacer. La mayor parte de los estudios se han centrado en zonas montanas y/o singulares o bien en los entornos de las residencias de los especialistas. Esto ha producido un importante sesgo en el conocimiento de las distribuciones que es necesario solventar realizando estudios sistemáticos centrados en conseguir una muestra representativa de los principales gradientes ambientales y geográficos de la Península. Precisamente, el objetivo del presente trabajo es contribuir a reducir de forma significativa las lagunas en el conocimiento de la distribución de los briófitos epífitos ibéricos. Para ello, se ha estudiado buena parte de las mesetas centrales, incluyendo las porciones españolas de las cuencas del Duero y del Tajo, dos de las regiones menos exploradas de la Península Ibérica. El catálogo resultante incluye 89 especies de briófitos, entre las que hay 9 hepáticas y 80 musgos. El presente estudio aporta además 72 nuevas citas provinciales y amplía significativamente la distribución conocida de un buen número de especies. Queda patente la importancia de llevar a cabo muestreos sistemáticos representativos de los gradientes ambientales y geográficos en zonas poco exploradas de modo que se vayan rellenando los huecos en el conocimiento de las distribuciones de los briófitos ibéricos.[EN] Knowledge on the diversity and distributions of the Iberian bryophytes has experienced a remarkable progress in the last decades. As a consequence, the taxonomy of the Iberian bryophytes is relatively well known. However, regarding the distribution and abundance of species across the territory large knowledge gaps e xist. To date, most of the studies have been centered either in mountainous regions or in singular areas or accessible sites in the vicinity of specialist's residences. This has produced important sampling biases in the knowledge on the species distributions. Thus, to improve the quality of the data at hand, it is necessary to perform systematic surveys focused on attaining a representative sample of the main geographic and environmental gradients of the Iberian Peninsula. Within this broad objective the specific aim of this work is to contribute to significantly reduce the knowledge gaps on the distribution of Iberian epiphytic bryophytes. To do so, we have studied a large part of the Iberian plateaus including the Duero and Tajo basins within the Spanish territory, two of the least explored regions within the Iberian Peninsula. The obtained catalogue includes 89 bryophyte species including 9 liverworts and 80 mosses. Besides, we provide 72 provincial novelties that significantly enlarge the known distribution of a number of species. Altogether these results evidence that to fill in current knowledge gaps it is necessary to perform systematic survey campaigns aimed at representing the geographic and environmental variability of the territory.Este trabajo ha sido financiado por los proyectos concedidos por el Ministerio de Economía y Competitividad (CGL2013-43246-P) y el Ministerio de Ciencia e Innovación (CGL2011-28857/BOS) españoles. N.G. Medina realizó el trabajo con una beca del Ministerio de Educación (AP2007-00905).Peer Reviewe

A probabilistic approach to risk assessment of slow slope movements

Hazard

Identification and frequency of consumption of wild edible plants over a year in central Tunisia: a mixed-methods approach

Objective: To identify wild plants used as food and assess their frequency of consumption over a year in a region of Tunisia where agriculture is undergoing a major transformation from smallholder farming to an intensive high-input agricultural system. Design: Qualitative ethnobotanical study followed by a survey of women's frequency of consumption of wild plants conducted using FFQ at quarterly intervals. Setting: Sidi Bouzid governorate of central Tunisia. Participants: Mixed-gender group of key informants (n 14) and focus group participants (n 43). Survey sample of women aged 20-49 years, representative at governorate level (n 584). Results: Ethnobotanical study: thirty folk species of wild edible plants corresponding to thirty-five taxa were identified by key informants, while twenty folk species (twenty-five taxa) were described by focus groups as commonly eaten. Population-based survey: 98 % of women had consumed a wild plant over the year, with a median frequency of 2 d/month. Wild and semi-domesticated fennel (Foeniculum vulgare Mill. and Anethum graveolens) was the most frequently consumed folk species. Women in the upper tertile of wild plant consumption frequency were more likely to be in their 30s, to live in an urban area, to have non-monetary access to foods from their extended family and to belong to wealthier households. Conclusions: In this population, wild edible plants, predominantly leafy vegetables, are appreciated but consumed infrequently. Their favourable perception, however, offers an opportunity for promoting their consumption which could play a role in providing healthy diets and mitigating the obesity epidemic that is affecting the Tunisian population