Evaluación del rendimiento del servicio de videostreaming adaptativo en redes inalámbricas

YouTube Live is one of the most popular services on the Internet, enabling an easy streaming of a live video with acceptable video quality. Thus, understanding user´s perception of this service is of the utmost importance for network operators. The image Quality delivered and user videoplayback behavior on YouTube Live streaming are important keys to ensure an adequate Quality of Experience (QoE). In this paper, an analytical model, and stacked Bar Graph to estimate the QoE for encrypted YouTube Live service from packet-level data collected in the interfaces of a wireless network is presented. The inputs to the model are Transport Control Protocol (TCP)/Internet Protocol (IP) metrics, from which two Service Key Performance Indicators (S-KPIs) are estimated, namely video quality level (itag) and, videoplayback connection ratio. The model is developed with an experimental platform, consisting of a user terminal agent, a WiFi wireless network, a network-level emulator, a Mitmproxy and a probe software. Model assessment is carried out by comparing S-KPI estimates with measurements from the terminal agent under different network conditions introduced by the network emulator.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. Ministerio de Economía y Competitividad (Proyecto TEC2015-69982-R, UNMA13-1E-1864), y FEDER

Space-Time Trade-offs for Stack-Based Algorithms

In memory-constrained algorithms we have read-only access to the input, and the number of additional variables is limited. In this paper we introduce the compressed stack technique, a method that allows to transform algorithms whose space bottleneck is a stack into memory-constrained algorithms. Given an algorithm \alg\ that runs in O(n) time using $\Theta(n)$ variables, we can modify it so that it runs in $O(n^2/s)$ time using a workspace of O(s) variables (for any $s\in o(\log n)$) or $O(n\log n/\log p)$ time using $O(p\log n/\log p)$ variables (for any $2\leq p\leq n$). We also show how the technique can be applied to solve various geometric problems, namely computing the convex hull of a simple polygon, a triangulation of a monotone polygon, the shortest path between two points inside a monotone polygon, 1-dimensional pyramid approximation of a 1-dimensional vector, and the visibility profile of a point inside a simple polygon. Our approach exceeds or matches the best-known results for these problems in constant-workspace models (when they exist), and gives the first trade-off between the size of the workspace and running time. To the best of our knowledge, this is the first general framework for obtaining memory-constrained algorithms

Publicização do direito privado e liberdade de contratar

Discorre sobre a publicização do direito privado e liberdade de contratar. Analisa as transformações do direito privado e o fenômeno da descodificação na sociedade contemporânea. Tece sobre os limites á liberdade de contratar e sobre a inserção de cláusulas atípicas em contratos típicos e pactuação de contratos atípicos. Trata do princípio social dos contratos da socialidade, eticidade, da boa fé e da justiça contratual

Normal spatial learning and improved spatial working memory in mice (mus musculus) lacking dopamine d4 receptors

Dopamine terminals in the hippocampus and prefrontal cortex modulate cognitive processes such as spatial learning and working memory. Because dopamine D4 receptors are expressed in these brain areas we have analyzed mutant mice lacking this receptor subtype (Drd4-/-). Wild-type and Drd4-/- mice were challenged in two spatial learning paradigms: the Morris water maze and an alternation T-maze. Drd4-/- mice showed normal place learning ability to find a hidden platform based on spatial extra-maze cues. In addition, Drd4-/- mice were able to find a new platform location with the same learning plasticity as wild type-mice. Spatial working memory assessed on a T maze showed that Drd4-/- mice were more efficient than wild-type mice in acquiring the maximum plateau of correct alternation scores. These results provide further evidence that the functional consequence of lacking D4 receptors is more evident in behaviors dependent on the integrity of the prefrontal cortex.Fil: Falzone, Tomas Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres"; ArgentinaFil: Avale, Maria Elena. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres"; ArgentinaFil: Gelman, Diego Matias. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres"; ArgentinaFil: Rubinstein, Marcelo. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres"; Argentin

Identificación de un aislamiento argentino de Spodoptera frugiperda granulovirus

La oruga militar tardía, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), es una plaga importante del maíz. Debido al impacto ambiental y a la aparición de resistencia causados por los pesticidas químicos y los eventos transgénicos, el uso de baculovirus resulta una alternativa útil y saludable para su control en estrategias de manejo integrado de plagas. En este trabajo reportamos la identificación de un nuevo aislamiento del granulovirus de la S. frugiperda nativo de la región central de Argentina, SfGV ARG. Se observó que larvas infectadas con SfGV ARG mostraron coloración amarillenta, hinchazón y, en algunos casos, lesiones graves en los últimos segmentos abdominales. Se confirmó la identidad del aislamiento por secuenciación de fragmentos de los genes lef-8, lef-9 y granulina, y por cálculo de distancias evolutivas usando el parámetro de Kimura-2. El patrón de restricción generado con el ADN genómico de SfGV ARG permitió estimar un tamaño de genoma de al menos 135 kb.The fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), is an important maize pest. Due to the environmental impact and emergence of resistance caused by chemical pesticides and transgenic events, the use of baculoviruses becomes a safe and useful alternative for its control in integrated pest management strategies. Here we report the identification of a novel isolate of a granulovirus of S. frugiperda native to the central region of Argentina, named SfGV ARG. We observed that larvae infected with SfGV ARG showed a yellowish coloration, swollen body and, in some cases, severe lesions in the last abdominal segments. We confirmed the identity of the isolate by sequencing fragments of the lef-8, lef-9 and granulin genes and by calculating evolutionary distances using the Kimura-2-Parameter model. SfGV ARG DNA restriction pattern allowed to estimate a genome of at least 135 kb.Fil: Pidre, Matias Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Biotecnología y Biología Molecular. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Biotecnología y Biología Molecular; ArgentinaFil: Sabalette, Karina Belén. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Biotecnología y Biología Molecular. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Biotecnología y Biología Molecular; ArgentinaFil: Romanowski, Victor. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Biotecnología y Biología Molecular. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Biotecnología y Biología Molecular; ArgentinaFil: Ferrelli, Maria Leticia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Biotecnología y Biología Molecular. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Biotecnología y Biología Molecular; Argentin

Socioemotional wealth preservation in family firms

In this article, we review literature on socioemotional wealth. We explain how the concept of socioemotional wealth builds on previous family firm research showing that family-owners derive utility from the nonfinancial aspects of their firm. We also discuss how family firms' need for socioemotional wealth preservation explains behavioral differences between family and nonfamily firms in managerial decision making. Finally, we discuss the current state of socioemotional wealth research and propose potential directions for future research

Larger investment in roots in southern range-edge populations of Scots pine is associated with increased growth and seedling resistance to extreme drought in response to simulated climate change

Extreme climate events such as heat waves or severe drought have the potential to fundamentally alter species dynamics, and are expected to increase in frequency in the coming decades. Early life stages of plant species are highly sensitive to these variations, with the potential for profound consequences for plant communities. In order to explore the response of Scots pine (Pinus sylvestris L.) seedlings to predicted increases in temperature and extreme drought, we performed a controlled-conditions experiment using growth chambers to simulate (1) current and future temperatures expected at the southernmost edge of the range, (2) current and drier growing seasons before an acute summer drought, and (3) drought alleviation by sporadic rainy events during summer. We analysed the response of seedlings by assessing survival, growth, biomass allocation and isotopic discrimination. Southern range-edge seedlings were compared under same conditions with those from the northern range edge, which experience cooler and wetter conditions throughout the year. The combination of extreme drought and the predicted temperature rise severely reduced overall survival for both provenances. A reduction in precipitation before the onset of drought diminished the survival and final biomass of seedlings, while the interruption of summer drought drastically increased survival probabilities. Southern seedlings invested a higher proportion of their biomass in roots, which conferred on them higher growth, higher survival probabilities, better nutritional status and lower drought stress. These results help us to understand the mechanisms of local adaptation at the southern range edge and indicate southern populations as a valuable genetic resource to buffer the response of Scots pine against such extreme climatic events

Convex Hulls in Polygonal Domains

We study generalizations of convex hulls to polygonal domains with holes. Convexity in Euclidean space is based on the notion of shortest paths, which are straight-line segments. In a polygonal domain, shortest paths are polygonal paths called geodesics. One possible generalization of convex hulls is based on the "rubber band" conception of the convex hull boundary as a shortest curve that encloses a given set of sites. However, it is NP-hard to compute such a curve in a general polygonal domain. Hence, we focus on a different, more direct generalization of convexity, where a set X is geodesically convex if it contains all geodesics between every pair of points x,y in X. The corresponding geodesic convex hull presents a few surprises, and turns out to behave quite differently compared to the classic Euclidean setting or to the geodesic hull inside a simple polygon. We describe a class of geometric objects that suffice to represent geodesic convex hulls of sets of sites, and characterize which such domains are geodesically convex. Using such a representation we present an algorithm to construct the geodesic convex hull of a set of O(n) sites in a polygonal domain with a total of n vertices and h holes in O(n^3h^{3+epsilon}) time, for any constant epsilon > 0