“That world is not for me”: Constructing a personal sense of opposition against school obligations

This study contributes to the contemporary discussion on school drop-out. Based on ethnographic materials I analyze the life contexts of working-class families in Mexico. Two case-stories from these materials on school drop-outs are presented and analyzed here. These two young people constructed narrative self-understandings and orientations about their lives and school drop-out in which they describe their experiences of school as a way to participate in "multiple worlds" across different social contexts in search of more rewarding life options than school. Confronted with collective cultural meanings about school, children and teenagers are able to construct a personal sense legitimating or resisting these collective meanings. This is occurring in a situation where important changes are taking place across generations concerning the meaning of school resulting from historical, economical and national changes and from the ways in which people use and enact collective cultural meanings about school. I argue for a reevaluation of the forms of participation of working class families and children in school. And I conclude that we need to replace the predominant disconnected understanding of the value of school learning and school knowledge with an understanding of the meaning of school in children's and teenagers' participation across different contexts with different relations to others

Design and Fabrication of Liquid Scintillator Counter

Pacific Northwest National Laboratory (PNNL) is currently developing an ultra-low background liquid scintillator counter (ULB LSC) in the shallow underground laboratory. At a depth of 35-meters water-equivalent, the underground laboratory has a multi-layered shielding to keep out cosmic-ray induced background. The ULB LSC, which is located in a clean room facility, is a multi-layered design made up of various materials, including plastic scintillator veto panels, borated polyethylene, lead and copper. These layers help lower the contributions of the terrestrial background and intrinsic background, resulting from the impurities present in the materials, to the overall background count rate observed by the detectors. After the completion of the instrument, the first liquid scintillation sample will be tested using a pulley-like design. The design consists of a sample holder which holds the vial in place as it is lowered down into a light guide. The second component of the design is a piece which helps lower the sample holder in the correct orientation into the light guide in order to maximize light output and collection efficiency. The system is designed using Solidworks, a computer aided design (CAD) program, and 3D printed using Acrylonitrile Butadiene Styrene (ABS) plastic. The design for the sample holder is based off of another more complex design originally made of copper. This simplified sample handling design will accelerate the project toward initial data collection, an important milestone toward validating the UBL LSC system concept

Effect of Precipitation on Cryogenic Toughness of N-Containing Austenitic Stainless Steels After Aging

This chapter shows the effect of intergranular precipitation on the cryogenic toughness of N-containing austenitic stainless steels in comparison to that for 316-type austenitic stainless steels. First part of the chapter deals with the thermodynamic stability and growth kinetics of the precipitated phases in the austenite matrix based on Thermo-Calc software. To continue, the experimental evolution of precipitation for N-containing steels is compared to that of 316-type steel and the difference between them are explained based on the Thermo-Calc PRISMA-calculated results. Finally, the effect of intergranular precipitation on the cryogenic fracture toughness is also analyzed using Charpy V‐Notch impact test results. The fracture mode is also related to the precipitation characteristics

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

Agricultural potential in Latin America and Caribbean for biofuels for transport

93 p.The present study presents a general assessment of the productive capacity of Latin American countries for producing biomass1. Biomass can be transformed in secondary liquid energy carriers like biodiesel and bioethanol, fossil fuels substitutes. The document begins with the description of the characteristics of currently used energy crops2 world wide. A specific analysis of Latin American productive conditions was then carried out to determine if the region has the potential to reach, at least, 5% blend levels3. The land availability and energy crop yields for biomass production were also projected for the year 2025, together with two alternative raw materials i.e. waste crops and field residues. Finally, the effects of a demand increase; producer subsidy and price support on energy crop markets were assessed. It was determined that most of Latin American countries could produce sufficient biomass to reach 5% blends. There is land availability for biomass production in 2025 mostly in South American countries. Potentially attainable blends of most Latin American countries for the year 2025, using biomass from agricultural energy crops, are between 30% and 91% for biodiesel, and between 20% and 206% for bioethanol. Blend estimates from forestry biomass are even higher and from residues are much lower. The “price support” measure causes the highest net welfare gain in Latin America countries (1.844 Mill. US$) as well as in the Rest of the World (1.623 Mill. US$) , whereas the demand shift provokes in the Rest of the World a net welfare loss of 761 Mill. US$

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

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

Application of Phase-Field Method to the Analysis of Phase Decomposition of Alloys

This chapter is focused on the application of the phase-field method to the analysis of phase decomposition during the isothermal aging of alloys. The phase-field method is based on a numerical solution of either the nonlinear Cahn-Hilliard equation or the Cahn-Allen equation. These partial differential equations can be solved using the finite difference method among other numerical methods. The phase-field method has been applied to analyze different types of phase transformations in alloys, such as phase decomposition, precipitation, recrystallization, grain growth, solidification of pure metals and alloys, martensitic transformation, ordering reactions, and so on. One of the main advantages of phase-field method is that this method permits to follow the microstructure evolution in two or three dimensions as the time of phase transformations progresses. Thus, the morphology, size, and size distribution could be determined to follow their corresponding growth kinetics. Additionally, the evolution of chemical composition can also be followed during the phase transformations. Furthermore, both Allen-Cahn and Cahn-Hilliard equations can be solved simultaneously to analyze the presence of ordered phases or magnetic domains in alloys