Efectos en El Salvador de las lluvias torrenciales, tormenta tropical Stan y erupción del volcán Ilamatepec (Santa Ana), octubre del 2005

Incluye Bibliografía

Commercial policy in the underdeveloped countries (from the point of view of Latin America)

Publicado también en español: La política comercial en los países insuficientemente desarrollados desde el punto de vista latinoamericano. Economía, v. 19, No 69-70, p 25-45, 4o trimestre 1960 y 1o trimestre 1961; y en: American Economic Review, v. 49, No 2, p. 251-273, May 1959

Cross-layer optimizations for multimedia distribution over Wireless Multimedia Sensor Networks and Flying Ad-Hoc Networks with quality of experience support

The proliferation of multimedia content and the demand for new audio or video services have fostered the development of a new era based on multimedia information, which allowed the evolution of Wireless Multimedia Sensor Networks (WMSNs) and also Flying Ad-Hoc Networks (FANETs). In this way, live multimedia services require realtime video transmissions with a low frame loss rate, tolerable end-to-end delay, and jitter to support video dissemination with Quality of Experience (QoE) support. Hence, a key principle in a QoE-aware approach is the transmission of high priority frames (protect them) with a minimum packet loss ratio, as well as network overhead. Moreover, multimedia content must be transmitted from a given source to the destination via intermediate nodes with high reliability in a large scale scenario. The routing service must cope with dynamic topologies caused by node failure or mobility, as well as wireless channel changes, in order to continue to operate despite dynamic topologies during multimedia transmission. Finally, understanding user satisfaction on watching a video sequence is becoming a key requirement for delivery of multimedia content with QoE support. With this goal in mind, solutions involving multimedia transmissions must take into account the video characteristics to improve video quality delivery. The main research contributions of this thesis are driven by the research question how to provide multimedia distribution with high energy-efficiency, reliability, robustness, scalability, and QoE support over wireless ad hoc networks. The thesis addresses several problem domains with contributions on different layers of the communication stack. At the application layer, we introduce a QoE-aware packet redundancy mechanism to reduce the impact of the unreliable and lossy nature of wireless environment to disseminate live multimedia content. At the network layer, we introduce two routing protocols, namely video-aware Multi-hop and multi-path hierarchical routing protocol for Efficient VIdeo transmission for static WMSN scenarios (MEVI), and cross-layer link quality and geographical-aware beaconless OR protocol for multimedia FANET scenarios (XLinGO). Both protocols enable multimedia dissemination with energy-efficiency, reliability and QoE support. This is achieved by combining multiple cross-layer metrics for routing decision in order to establish reliable routes.

A note about splittings of groups and commensurability under a cohomological point of view

Let G be a group, let S be a subgroup with infinite index in G and let FSG be a certain Z2G-module. In this paper, using the cohomological invariant E(G, S, FSG) or simply E˜(G, S) (defined in [2]), we analyze some results about splittings of group G over a commensurable with S subgroup which are related with the algebraic obstruction “singG(S)" defined by Kropholler and Roller ([8]. We conclude that E˜(G, S) can substitute the obstruction “singG(S)" in more general way. We also analyze splittings of groups in the case, when G and S satisfy certain duality conditions.

Is the internal connection more efficient than external connection in mechanical, biological, and esthetical point of views? A systematic review

This systematic review aimed to evaluate if the internal connection is more efficient than the external connection and its associated influencing factors. A specific question was formulated according to the Population, Intervention, Control, and Outcome (PICO): Is internal connection more efficient than external connection in mechanical, biological, and esthetical point of views? An electronic search of the MEDLINE and the Web of Knowledge databases was performed for relevant studies published in English up to November 2013 by two independent reviewers. The keywords used in the search included a combination of dental implant and internal connection or Morse connection or external connection. Selected studies were randomized clinical trials, prospective or retrospective studies, and in vitro studies with a clear aim of investigating the internal and/or external implant connection use. From an initial screening yield of 674 articles, 64 potentially relevant articles were selected after an evaluation of their titles and abstracts. Full texts of these articles were obtained with 29 articles fulfilling the inclusion criteria. Morse taper connection has the best sealing ability. Concerning crestal bone loss, internal connections presented better results than external connections. The limitation of the present study was the absence of randomized clinical trials that investigated if the internal connection was more efficient than the external connection. The external and internal connections have different mechanical, biological, and esthetical characteristics. Besides all systems that show proper success rates and effectiveness, crestal bone level maintenance is more important around internal connections than external connections. The Morse taper connection seems to be more efficient concerning biological aspects, allowing lower bacterial leakage and bone loss in single implants, including aesthetic regions. Additionally, this connection type can be successfully indicated for fixed partial prostheses and overdenture planning, since it exhibits high mechanical stability.

Vacuum energy and the fixed point of QED

The vacuum energy of QED, as a function of the coupling constant α, is shown to have an absolute minimum at the critical coupling αc=π/3. The effect of chiral symmetry breaking diminishes as the coupling is increased. We argue that these aspects of the vacuum energy shall remain unaltered beyond the ladder approximation.

Women from the point of view of the Bukowskian narrator: the representation of the feminine universe in Erections, Ejaculations, Exhibitions and General Tales of Ordinary Madness

Pós-graduação em Letras - IBILCE

Chicana, Indian and Sudanese Perspectives of Teaching in the Academy: Three Levels of Experience in the Teaching-Learning and Social Environment

“Women of color from any culture or country face additional barriers in predominantly white institutions. This panel presents perspectives and experiences of three women from three cultures and three different levels of academia—a Chicana Latino visiting professor, a graduate teaching assistant from India, and a Sudanese graduate research assistant.”

The Effects of High Pressure on the Point of No Return in Simulated Penalty Kicks

We investigated the effects of high pressure on the point of no return or the minimum time required for a kicker to respond to the goalkeeper's dive in a simulated penalty kick task. The goalkeeper moved to one side with different times available for the participants to direct the ball to the opposite side in low-pressure (acoustically isolated laboratory) and high-pressure situations (with a participative audience). One group of participants showed a significant lengthening of the point of no return under high pressure. With less time available, performance was at chance level. Unexpectedly, in a second group of participants, high pressure caused a qualitative change in which for short times available participants were inclined to aim in the direction of the goalkeeper's move. The distinct effects of high pressure are discussed within attentional control theory to reflect a decreasing efficiency of the goal-driven attentional system, slowing down performance, and a decreasing effectiveness in inhibiting stimulus-driven behavior.

Correction of Severe Ptosis with a Silicone Implant Suspensor: 22 Years of Experience

Background: Patients with severe ptosis caused by poor or absent function of the levator muscle but with good frontalis muscle excursion usually benefit from a frontalis sling procedure. This is currently carried out using organic or inorganic material to connect the upper eyelid to the frontalis muscle. Methods: The aim of this study was to evaluate retrospectively 112 patients who underwent frontalis sling procedures between 1989 and 2011 using a preformed silicone implant suspensor to correct severe ptosis. Results: The results obtained using this technique were good or fair in 95.54 percent of the cases and poor in 4.46 percent of the cases. The authors discuss the results of the study and the cases in which the procedure should be indicated and highlight the advantages of the method. Conclusion: The availability of this low-cost sterile device, together with the fact that it is ready to use, requires less invasive surgery, saves time, and is sufficiently versatile to allow adjustments to be made at any time, makes the silicone eyelid sling an attractive choice for correcting ptosis. (Plast. Reconstr. Surg. 129: 453e, 2012.)

INFERENCES FOR THE CHANGE-POINT OF THE EXPONENTIATED WEIBULL HAZARD FUNCTION

In many applications of lifetime data analysis, it is important to perform inferences about the change-point of the hazard function. The change-point could be a maximum for unimodal hazard functions or a minimum for bathtub forms of hazard functions and is usually of great interest in medical or industrial applications. For lifetime distributions where this change-point of the hazard function can be analytically calculated, its maximum likelihood estimator is easily obtained from the invariance properties of the maximum likelihood estimators. From the asymptotical normality of the maximum likelihood estimators, confidence intervals can also be obtained. Considering the exponentiated Weibull distribution for the lifetime data, we have different forms for the hazard function: constant, increasing, unimodal, decreasing or bathtub forms. This model gives great flexibility of fit, but we do not have analytic expressions for the change-point of the hazard function. In this way, we consider the use of Markov Chain Monte Carlo methods to get posterior summaries for the change-point of the hazard function considering the exponentiated Weibull distribution.

ABSENCE OF STABILIZATION POINT OF THE SPECIES ACCUMULATION CURVE IN TROPICAL FORESTS

The definition of the sample size is a major problem in studies of phytosociology. The species accumulation curve is used to define the sampling sufficiency, but this method presents some limitations such as the absence of a stabilization point that can be objectively determined and the arbitrariness of the order of sampling units in the curve. A solution to this problem is the use of randomization procedures, e. g. permutation, for obtaining a mean species accumulation curve and empiric confidence intervals. However, the randomization process emphasizes the asymptotical character of the curve. Moreover, the inexistence of an inflection point in the curve makes it impossible to define objectively the point of optimum sample size.

A new method for calculating the convergent point of a moving group

Context. Convergent point (CP) search methods are important tools for studying the kinematic properties of open clusters and young associations whose members share the same spatial motion. Aims. We present a new CP search strategy based on proper motion data. We test the new algorithm on synthetic data and compare it with previous versions of the CP search method. As an illustration and validation of the new method we also present an application to the Hyades open cluster and a comparison with independent results. Methods. The new algorithm rests on the idea of representing the stellar proper motions by great circles over the celestial sphere and visualizing their intersections as the CP of the moving group. The new strategy combines a maximum-likelihood analysis for simultaneously determining the CP and selecting the most likely group members and a minimization procedure that returns a refined CP position and its uncertainties. The method allows one to correct for internal motions within the group and takes into account that the stars in the group lie at different distances. Results. Based on Monte Carlo simulations, we find that the new CP search method in many cases returns a more precise solution than its previous versions. The new method is able to find and eliminate more field stars in the sample and is not biased towards distant stars. The CP solution for the Hyades open cluster is in excellent agreement with previous determinations.