553 research outputs found
The Evolution of Los Zetas in Mexico and Central America: Sadism as an Instrument of Cartel Warfare
View the Executive SummaryThe United States has diplomatic relations with 194 independent nations. Of these, none is more important to America than Mexico in terms of trade, investment, tourism, natural resources, migration, energy, and security. In recent years, narco-violence has afflicted Mexico with more than 50,000 drug-related murders since 2007 and some 26,000 men, women, and children missing. President Enrique Peña Nieto has tried to divert national attention from the bloodshed through reforms in energy, education, anti-hunger, health-care, and other areas. Even though the death rate has declined since the chief executive took office on December 1, 2012, other crimes continue to plague his nation. Members of the business community report continual extortion demands; the national oil company PEMEX suffers widespread theft of oil, gas, explosives, and solvents (with which to prepare methamphetamines); hundreds of Central American migrants have shown up in mass graves; and the public identifies the police with corruption and villainy. Washington policymakers, who overwhelmingly concentrate on Asia and the Mideast, would be well-advised to focus on the acute dangers that lie principally below the Rio Grande, but whose deadly avatars are spilling into our nation.https://press.armywarcollege.edu/monographs/1501/thumbnail.jp
Site of Origin and Reflex Behavior of Postsynaptic Negative Potentials Recorded from the Spinal Cord ‡
Variation of sensitized fluorescence with penetration depth of incident 2537A radiation
An investigation of the sensitized fluorescence of a thallium and mercury mixture using a variable depth cell and photomultiplier type of detection is discussed. Data are given to indicate the variation of the intensity of the 3519A thallium line as a function of thallium temperature, as a function of mercury temperature, and as a function of cell depth. Explanations of results require the use of generally accepted ideas concerning energy transfer, emission, and absorption
Terahertz Magneto Optical Polarization Modulation Spectroscopy
We report the development of new terahertz techniques for rapidly measuring
the complex Faraday angle in systems with broken time-reversal symmetry using
the cyclotron resonance of a GaAs two-dimensional electron gas in a magnetic
field as a system for demonstration of performance. We have made polarization
modulation, high sensitivity (< 1 mrad) narrow band rotation measurements with
a CW optically pumped molecular gas laser, and by combining the distinct
advantages of terahertz (THz) time domain spectroscopy and polarization
modulation techniques, we have demonstrated rapid broadband rotation
measurements to < 5 mrad precision.Comment: 25 pages including 7 figures, introduces use of rotating polarizer
with THz TDS for Complex Faraday Angle determinatio
Geometric Control of Human Stem Cell Morphology and Differentiation
During tissue morphogenesis, stem cells and progenitor cells migrate, proliferate, and differentiate, with striking changes in cell shape, size, and acting mechanical stresses. The local cellular function depends on the spatial distribution of cytokines as well as local mechanical microenvironments in which the cells reside. In this study, we controlled the organization of human adipose derived stem cells using micro-patterning technologies, to investigate the influence of multi-cellular form on spatial distribution of cellular function at an early stage of cell differentiation. The underlying role of cytoskeletal tension was probed through drug treatment. Our results show that the cultivation of stem cells on geometric patterns resulted in pattern- and position-specific cell morphology, proliferation and differentiation. The highest cell proliferation occurred in the regions with large, spreading cells (such as the outer edge of a ring and the short edges of rectangles). In contrast, stem cell differentiation co-localized with the regions containing small, elongated cells (such as the inner edge of a ring and the regions next to the short edges of rectangles). The application of drugs that inhibit the formation of actomyosin resulted in the lack of geometrically specific differentiation patterns. This study confirms the role of substrate geometry on stem cell differentiation, through associated physical forces, and provides a simple and controllable system for studying biophysical regulation of cell function
Modeling long-term persistence in hydroclimatic time series using a hidden state Markov model
A hidden state Markov (HSM) model is developed as a new approach for generating hydroclimatic time series with long-term persistence. The two-state HSM model is motivated by the fact that the interaction of global climatic mechanisms produces alternating wet and dry regimes in Australian hydroclimatic time series. The HSM model provides an explicit mechanism to stochastically simulate these quasi-cyclic wet and dry periods. This is conceptually sounder than the current stochastic models used for hydroclimatic time series simulation. Models such as the lag-one autoregressive (AR(1)) model have no explicit mechanism for simulating the wet and dry regimes. In this study the HSM model was calibrated to four long-term Australian hydroclimatic data sets. A Markov Chain Monte Carlo method known as the Gibbs sampler was used for model calibration. The results showed that the locations significantly influenced by tropical weather systems supported the assumptions of the HSM modeling framework and indicated a strong persistence structure. In contrast, the calibration of the AR(1) model to these data sets produced no statistically significant evidence of persistence.Mark Thyer and George Kucze
From Passive to Radical Revolution in Venezuela’s Populist Project
In December 2001, Hugo Chávez and others changed Venezuela’s Bolivarian revolutionary project, which consisted of replacing a corrupt and elitist constitution with a fair and popular one, into a radical one. In its early stages the project corresponded to what Gramsci called a “passive revolution.” Attempts by opposition forces to crush the construction of a new populist hegemony (a coup in April 2002 and an indefinite strike in December 2002) were met with popular mobilization that reaffirmed Chávez’s hegemonic project. The radical revolution consisted of social programs designed to alleviate the suffering of the poor and consolidated a new hegemonic structure among Venezuela’s lower classes. The concept of “radical revolution” provides a theoretical alternative for assessing the extent to which a political project can be described as populist
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