Amplitude Modulation and Relaxation-Oscillation of Counterpropagating Rolls within a Broken-Symmetry Laser-Induced Electroconvection Strip

We report a liquid-crystal pattern-formation experiment in which we break the lateral (translational) symmetry of a nematic medium with a laser-induced thermal gradient. The work is motivated by an improved measurement (reported here) of the temperature dependence of the electroconvection threshold voltage in planar-nematic 4-methoxybenzylidene-4-butylaniline (MBBA). In contrast with other broken-symmetry-pattern studies that report a uniform drift, we observe a strip of counterpropagating rolls that collide at a sink point, and a strong temporally periodic amplitude modulation within a width of 3-4 rolls about the sink point. The time dependence of the amplitude at a fixed position is periodic but displays a nonsinusoidal relaxation-oscillation profile. After reporting experimental results based on spacetime contours and wavenumber profiles, along with a measurement of the change in the drift frequency with applied voltage at a fixed control parameter, we propose some potential guidelines for a theoretical model based on saddle-point solutions for Eckhaus-unstable states and coupled complex Ginzburg-Landau equations. Published in PRE 73, 036317 (2006).Comment: Published in Physical Review E in March 200

Carl Djerassi: “In memoriam”. Pionero de la creación del “anticonceptivo oral” y hombre polifacético

ResumenCarl Djerassi nació en Viena en 1923 y emigró a New York en 1939 donde escribió una carta a Eleanor Roosevelt solicitando un apoyo para continuar sus estudios, graduándose en química en 1942 y obteniendo su doctorado en química en la Universidad de Wisconsin en 1945. Sintetizó el esteroide básico del “anticonceptivo oral”, genéricamente conocido como noretisterona. Desde el siglo pasado se sabía que la administración parenteral de estrógenos y progesterona inhibía la ovulación, pero resultaba de un costo muy elevado. Jorge Rosenkranz invitó a Djerassi a incorporarse a Syntex para buscar la síntesis de progesterona, quienes junto con Luis E. Miramontes emplearon el esteroide esencial obtenido del barbasco descubierto por Rusell E. Marker. De esta manera se consiguió industrializar el anticonceptivo hormonal oral conocido trivialmente como la “píldora”.Djerassi se podría considerar como un conspicuo químico, biólogo y sociólogo; incursionó en la literatura, fue coleccionista de arte y benefactor de artistas. Fue presidente de Syntex en México y en Palo Alto. Falleció el 30 de enero de 2015 a la edad de 91 años en San Francisco California.AbstractCarl Djerassi (Vienna, 1923) immigrated to New York in 1939, where he wrote to Eleanor Roosevelt requesting funding to continue his studies, graduating in chemistry in 1942, and acquiring a doctorate in chemistry at the University of Wisconsin in 1945. He synthesised the basic “oral contraceptive” steroid, known generically as norethisterone. Since the preceding century parenteral estrogens and progesterone had been known to inhibit ovulation, but producing them was very expensive. Jorge Rosenkranz invited Djerassi to join Syntex to work on progesterone synthesis; together with Luis E. Miramontes, the researchers used the essential steroid from barbasco [a Mexican yam] discovered by Russell E. Marker to make it possible to industrialise the oral hormonal contraceptive commonly known as “the pill”.Djerassi could be considered as a distinguished chemist, biologist and sociologist, who also pursued literature and was an art collector and artists’ benefactor. Past president of Syntex in Mexico and in Palo Alto, he died on 30 January 2015 at the age of 91 in San Francisco, California

Effects of Alcohol and Expectancy Upon Episodic Memory in Individuals Reporting Alcoholic Blackouts

In a within-subject placebo design, 10 heavy drinkers reporting alcoholic blackouts showed significant decrements in episodic memory when receiving alcohol but not on days when a placebo was given. Parallel deficits were observed on recall and recognition measures. On placebo days, self-ratings of intoxication were related to the degree of observed performance decrement. Memory deficits appear to be primarily pharmacologic rather than expectancy effects of drinking

The Code Stroke: medical evaluation by a pre-hospital attention service

In 1996, the NINDS (National Institute of Neurological Disorders and Treatment of Acute Stroke) published targets for the management of patients with acute cerebrovascular events, setting a time of 3 h or less for administration of thrombolytics, creating the Code Stroke. Objective: Evaluate the time between onset of symptoms and arrival at the emergency department of a hospital as prognostic factors in patients with cerebrovascular events attended by the prehospital emergency medical service in the metropolitan area of Monterrey, Nuevo Leon. Materials and methods: Calls received in the ED (EMME) between January and December 2012 were included in a retrospective cross-sectional study, with symptoms showing within the first 8 h or with an unknown onset. The Mann---Whitney test and Fisher’s exact test were used. Results: Thirty-six patients were included in the study. In 21, the final diagnosis was cerebral infarction, 5 patients were treated with thrombolysis (23.8%). They were divided into two groups: group 1 died or were left with severe neurological sequelae (n = 9) and Group 2 survived without sequelae or mild neurological sequelae (n = 12). The door hospital arrival time was 67 (29---116) min (Group 1) versus 54 (24---86) min (Group 2) (p = 0.110). The neurological status at the start of the event affected prognosis and mortality (p = 0.018). Conclusions: There are few studies analyzing the time between the inception of the symptomatology and the arrival to the emergency room. In our study 23.8% of this series were thrombolyzed, which puts us in the range of international statistics, compared to the series published by Geffner-Sclarsky et al. The population of this study is small so it is not able to show statistical differences, but the few studies that evaluate the Code Stroke in Mexico open the doors to future work with a larger population in Latin American society

Fuels treatment and wildfire effects on runoff from Sierra Nevada mixed-conifer forests

We applied an eco-hydrologic model (Regional Hydro-Ecologic Simulation System [RHESSys]), constrained with spatially distributed field measurements, to assess the impacts of forest-fuel treatments and wildfire on hydrologic fluxes in two Sierra Nevada firesheds. Strategically placed fuels treatments were implemented during 2011–2012 in the upper American River in the central Sierra Nevada (43 km2) and in the upper Fresno River in the southern Sierra Nevada (24 km2). This study used the measured vegetation changes from mechanical treatments and modelled vegetation change from wildfire to determine impacts on the water balance. The well-constrained headwater model was transferred to larger catchments based on geologic and hydrologic similarities. Fuels treatments covered 18% of the American and 29% of the Lewis catchment. Averaged over the entire catchment, treatments in the wetter central Sierra Nevada resulted in a relatively light vegetation decrease (8%), leading to a 12% runoff increase, averaged over wet and dry years. Wildfire with and without forest treatments reduced vegetation by 38% and 50% and increased runoff by 55% and 67%, respectively. Treatments in the drier southern Sierra Nevada also reduced the spatially averaged vegetation by 8%, but the runoff response was limited to an increase of less than 3% compared with no treatment. Wildfire following treatments reduced vegetation by 40%, increasing runoff by 13%. Changes to catchment-scale water-balance simulations were more sensitive to canopy cover than to leaf area index, indicating that the pattern as well as amount of vegetation treatment is important to hydrologic response

Singularidades de un sistema de gobierno indígena del norte de México. El carácter interétnico y etnojerarquizado del sistema de cargos ódami

This paper becomes part of native’s anthropologic studies in Sierra Tarahumara, one of the bigger areas of North Mexico. Concretely, the authors talk about two of the most important singular characteristics of the Odami government system. Those characteristics are particularly different of the Mesoamerican ones, which have profusely been described in the ethnographic literature. First of all, the authors expose the very singular Odami territoriality. The main characteristic of this kind of phenomenon is that the community is divided in two halves: the «abajeños» and the «arribeños». This division transforms the Odami government system organization. Secondly, the authors emphasize the inter-ethnic end ethnohierarchized Odami organization, in the way of a native people –the Raramuri– is clearly subordinate to the government hierarchy of another native people –the Odami–.El presente texto se ubica dentro de los estudios antropológicos de los pueblos indígenas de la Sierra Tarahumara en el norte de México. Caracterizamos concretamente dos de las singularidades más importantes del sistema de gobierno de los ódami, las cuales consideramos distinguen tal sistema de muchos otros que han sido descritos profusamente en la literatura etnográfica, principalmente entre pueblos de tradición mesoamericana. En particular, señalamos por un lado la muy particular territorialidad ódami, con una división de la comunidad en dos mitades (los abajeños y los arribeños), división que incide directamente en el sistema de gobierno; y por el otro, destacamos el carácter interétnico y etnojerarquizado del sistema de gobierno, de tal manera que ciertas comunidades indígenas rarámuri, reconocen abiertamente su subordinación ante los principales cargos del gobierno de otro pueblo étnicamente distinto –los ódami–

Induced Force Hovering of Spherical Robot by Under-Actuated Control of Dual Rotor

This chapter discusses the design and modelling of a spherical flying robot. The main objective is to control its hovering and omnidirectional mobility by controlling the air mass differential pressure between two asynchronous coaxial rotors that are aligned collinearly. The spherical robot design has embedded a gyroscopic mechanism of three rings that allow the rotors’ under-actuated mobility with 3DOF. The main objective of this study is to maintain the thrust force with nearly vertical direction. The change in pressure between rotors allows to vary the rotors’ tilt and pitch. The system uses special design propellers to improve the laminar air mass flux. A nonlinear fitting model automatically calibrates the rotors’ angular speed as a function of digital values. This model is the functional form that represents the reference input to control the rotors’ speed, validated by three types controllers: P, PI, and PID. The robot’s thrust and induced forces and flight mechanics are proposed and analysed. The simulation results show the feasibility of the approach

Boundary Layer Transition Flight Experiment Overview and In-Situ Measurements

In support of the Boundary Layer Transition Flight Experiment (BLTFE) Project, a manufactured protuberance tile was installed on the port wing of Space Shuttle Orbiter Discovery for the flights of STS-119 and STS-128. Additional instrumentation was also installed in order to obtain more spatially resolved measurements downstream of the protuberance. This paper provides an overview of the BLTFE Project, including the project history, organizations involved, and motivations for the flight experiment. Significant efforts were made to place the protuberance at an appropriate location on the Orbiter and to design the protuberance to withstand the expected environments. Efforts were also extended to understand the as-fabricated shape of the protuberance and the thermal protection system tile configuration surrounding the protuberance. A high-level overview of the in-situ flight data is presented, along with a summary of the comparisons between pre- and post-flight analysis predictions and flight data. Comparisons show that predictions for boundary layer transition onset time closely match the flight data, while predicted temperatures were significantly higher than observed flight temperatures

Partnering with Parteras: Multi-Collaborator International Service-Learning Project Impacts on Traditional Birth Attendants in Mexico

Medical students are increasingly seeking global health service-learning opportunities; however, the impact of these interventions is often not assessed. In this article, the authors describe a model for global health service-learning programs as well as a pilot tool for assessing program impacts on populations traditionally difficult to evaluate.  Specifically, a group of medical students from the United States, in collaboration with local health officials and a global NGO, successfully implemented a training program for parteras, or traditional birth attendants, in Mexico. The training included educational objectives from the Ministry of Health.  A pilot assessment tool was developed which included oral pretest and posttest self-reported knowledge and task-specific ability in 12 program-specific categories. The assessment was administered in an effort to determine educational impact: parteras, who were receptive to students as teachers, reported increased knowledge and skill in all topics except nutrition and postpartum care. The results of the assessment suggest that undergraduate medical students, when collaborating with a facilitating organization, community-based healthcare workers, and local ministries of health, can improve lay birth attendants’ confidence in basic obstetric knowledge and skills through global service-learning. Moreover, creative assessments are required to understand impacts on difficult to access populations.