Threshold logic implementation of a modular computer system design

Threshold logic implementation for LSI design of modular computer syste

Index of Skylab data available at Colorado School of Mines

There are no author-identified significant results in this report

Geologic and mineral and water resources investigations in western Colorado, using Skylab EREP data

The author has identified the following significant results. Skylab photographs are superior to ERTS images for photogeologic interpretation, primarily because of improved resolution. Lithologic contacts can be detected consistently better on Skylab S190A photos than on ERTS images. Color photos are best; red and green band photos are somewhat better than color-infrared photos; infrared band photos are worst. All major geologic structures can be recognized on Skylab imagery. Large folds, even those with very gentle flexures, can be mapped accurately and with confidence. Bedding attitudes of only a few degrees are recognized; vertical exaggeration factor is about 2.5X. Mineral deposits in central Colorado may be indicated on Skylab photos by lineaments and color anomalies, but positive identification of these features is not possible. S190A stereo color photography is adequate for defining drainage divides that in turn define the boundaries and distribution of ground water recharge and discharge areas within a basin

Cancer: repositioned to kill stem cells

Chemotherapy-resistant cancer stem cells make it hard to cure many forms of the disease. Repositioning an existing drug to tackle this problem could significantly improve treatment for one form of leukaemia

Generic phase diagram of active polar films

We study theoretically the phase diagram of compressible active polar gels such as the actin network of eukaryotic cells. Using generalized hydrodynamics equations, we perform a linear stability analysis of the uniform states in the case of an infinite bidimensional active gel to obtain the dynamic phase diagram of active polar films. We predict in particular modulated flowing phases, and a macroscopic phase separation at high activity. This qualitatively accounts for experimental observations of various active systems, such as acto-myosin gels, microtubules and kinesins in vitro solutions, or swimming bacterial colonies.Comment: 4 pages, 1 figur

Mechanical Instabilities of Biological Tubes

We study theoretically the shapes of biological tubes affected by various pathologies. When epithelial cells grow at an uncontrolled rate, the negative tension produced by their division provokes a buckling instability. Several shapes are investigated : varicose, enlarged, sinusoidal or sausage-like, all of which are found in pathologies of tracheal, renal tubes or arteries. The final shape depends crucially on the mechanical parameters of the tissues : Young modulus, wall-to-lumen ratio, homeostatic pressure. We argue that since tissues must be in quasistatic mechanical equilibrium, abnormal shapes convey information as to what causes the pathology. We calculate a phase diagram of tubular instabilities which could be a helpful guide for investigating the underlying genetic regulation

Spontaneous Oscillations of Collective Molecular Motors

We analyze a simple stochastic model to describe motor molecules which cooperate in large groups and present a physical mechanism which can lead to oscillatory motion if the motors are elastically coupled to their environment. Beyond a critical fuel concentration, the non-moving state of the system becomes unstable with respect to a mode with angular frequency omega. We present a perturbative description of the system near the instability and demonstrate that oscillation frequencies are determined by the typical timescales of the motors.Comment: 11 pages, Revtex, 4 pages Figure

Brownian Motors driven by Particle Exchange

We extend the Langevin dynamics so that particles can be exchanged with a particle reservoir. We show that grand canonical ensembles are realized at equilibrium and derive the relations of thermodynamics for processes between equilibrium states. As an application of the proposed evolution rule, we devise a simple model of Brownian motors driven by particle exchange. KEYWORDS: Langevin Dynamics, Thermodynamics, Open SystemsComment: 5 pages, late

Energy Transduction of Isothermal Ratchets: Generic Aspects and Specific Examples Close to and Far from Equilibrium

We study the energetics of isothermal ratchets which are driven by a chemical reaction between two states and operate in contact with a single heat bath of constant temperature. We discuss generic aspects of energy transduction such as Onsager relations in the linear response regime as well as the efficiency and dissipation close to and far from equilibrium. In the linear response regime where the system operates reversibly the efficiency is in general nonzero. Studying the properties for specific examples of energy landscapes and transitions, we observe in the linear response regime that the efficiency can have a maximum as a function of temperature. Far from equilibrium in the fully irreversible regime, we find a maximum of the efficiency with values larger than in the linear regime for an optimal choice of the chemical driving force. We show that corresponding efficiencies can be of the order of 50%. A simple analytic argument allows us to estimate the efficiency in this irreversible regime for small external forces.Comment: 16 pages, 10 figure

Psychosocial resilience among left-behind adolescents in rural Thailand: A qualitative exploration

When parents migrate, they often leave children behind with relatives. Despite being at higher risk of socio-emotional problems, many left-behind children have good health and social outcomes, suggesting their resilience. We sought to understand how adolescents with internal and international migrant parents build resilience in Thailand. We conducted qualitative interviews with 24 adolescents aged 10–19, and six caregivers, parents and community leaders. Interviews were transcribed, translated and analysed, drawing on techniques from grounded theory. We found that resilience was built in a context where for many families, migration was a financial necessity and the parent–child relationship was mainly phone-based. Adolescents built resilience using three key ‘resources’: warmth (love and understanding), financial support and guidance. Adolescents with insecure parent or caregiver relationships, or with caring responsibilities for relatives, were less likely to have access to these resources. These adolescents sought emotional and financial independence, prioritised friendships and identified role models to obtain key resources and build resilience. The findings indicate practical and psychosocial barriers to building resilience among left-behind adolescents in Thailand. Further work could explore pathways to mental illness in this population, interventions that build peer networks and caregiver–child relationships and the use of technology to support remote parenting