Simulations of beam dynamics in the CTF2 drive beam accelerator and bunch compressor

The purpose of this study is to simulate and to have a better understanding of the experimental limitation of the transmission in the CTF2 drive beam in function of the beam charge. In this note, the low energy part of the beam line is studied with the particle-tracking program PARMELA from the gun to the first 30 GHz section. Assuming the beam loading and space charge at 10nC/bunch, the settings of the magnetic components in Nov 98 configuration are discussed and slight modification have to be proposed to obtain a good matching and total transmission until the first 30GHz section. The possible limitation of transmission in the HCS for bigger beam size generation on the cathode is pointed out. Some particularities of the bunch compressor are shown as well as the effect of the bunch correlation quality, the deflection angle limitation and the phase shift induced in the train. Finally, transverse results are resumed and the simulated total transmission is validated by experiments. Beam parameters will be used by A. Riche [5] to study the wake-fields and the beam transmission in the downstream 30GHz sections

In the Wake of the End of the World: Stories

This collection of short stories came about from my growth as a passionate but imperfect feminist, reflecting on the place I call home—how the South and its politics shape us and how I learned to shape myself

Growth of the Marine Fish-Killing Phytoflagellate, Heterosigma Akashiwo Under Emerging Coastal Regimes: Temperature, Eutrophication and Ocean Acidification

Coastal oceans are fundamental to human economies, nutrition and recreation. Anthropogenic stressors have led to the acceleration of the nitrogen cycle, the accumulation of inorganic carbon in the earth’s atmosphere, the loss of UV-scavenging upper atmospheric ozone and the overall accumulation of deep elements from the earth’s crust to surface exposure. These changes have caused ocean acidification and eutrophication events in coastal waters and the impacts of these events on primary production and ocean biodiversity are not yet fully understood. This study examined the effects of predicted future ocean conditions (salinity, temperature, reduced seawater pH and modified nitrogen supplies), on the growth, photosynthesis and fatty acid composition of a key harmful algal bloom producing phytoflagellate predicted to dominate in the future ocean, Heterosigma akashiwo. Results from H. akashiwo NWFSC were compared to the marine diatom Thalassiosira weissflogii and the marine cyanobacterium, Synechococcus sp. Experimental pH levels represented ambient seawater (pH 8.1 or pH 8.2), and ecologically relevant pH levels predicted for the years 2050 and 2100 (pH 7.4 and pH 7.8, respectively). Findings showed that H. akashiwo experienced maximal growth rates at 20 practical salinity units, which increased with increasing temperatures predicted in a global climate change scenario (from 14.7 °C-24.4 °C). Altering pH environments did not demonstrate any notable change in growth rates of H. akashiwo compared to the other phytoplankton species. Rather, altering the nutrient environment (which occurs in coastal upwelling regimes) was the main driving force to change H. akashiwo productivity and intracellular fatty acid composition. Results from this research can provide a foundation for predicting future ocean acidification impacts on marine ecosystems, economies and fisheries productivity

Candela photo-injector experimental results with a dispenser photocathode

International audienceThe CANDELA photo-injector is a two cell S-band photo-injector. The dispenser photocathode is illuminated by a 500 fs pulse from a frequency-tripled Ti:sapphire laser. In this paper we report charge measurements showing that the dispenser photocathode has a quantum efficiency as high as 10-3. This efficiency decreases with a lifetime of 12 hours, but can be recovered by heating the cathode for 5 minute

Substance-Abusing Mothers and fathers\u27 Willingness to Allow Their Children to Receive Mental Health Treatment

The purpose of this study was to examine attitudes of substance-abusing mothers and fathers entering outpatient treatment toward allowing their children to participate in individual- or family-based interventions. Data were collected from a brief anonymous survey completed by adults at intake into a large substance abuse treatment program in western New York. Only one-third of parents reported that they would be willing to allow their children to participate in any form of mental health treatment. Results of chi-square analyses revealed that a significantly greater proportion of mothers reported that they would allow their children to participate in mental health treatment (41%) compared to fathers (28%). Results of logistic regression analyses revealed even after controlling for child age, mothers were more likely than fathers to indicate their willingness to allow their children to receive mental health treatment; however, type of substance abuse (alcohol versus drug abuse) was not associated with parents\u27 willingness to allow their children to receive treatment. Parental reluctance to allow their children to receive individual or family-based treatment is a significant barrier in efforts to intervene with these at-risk children

6'-Methoxy Raloxifene-analog enhances mouse bone properties with reduced estrogen receptor binding

Raloxifene (RAL) is an FDA-approved drug used to treat osteoporosis in postmenopausal women. RAL suppresses bone loss primarily through its role as a selective estrogen receptor modulator (SERM). This hormonal estrogen therapy promotes unintended side effects, such as hot flashes and increased thrombosis risk, and prevents the drug from being used in some patient populations at-risk for fracture, including children with bone disorders. It has recently been demonstrated that RAL can have significant positive effects on overall bone mechanical properties by binding to collagen and increasing bone tissue hydration in a cell-independent manner. A Raloxifene-Analog (RAL-A) was synthesized by replacing the 6-hydroxyl substituent with 6-methoxy in effort to reduce the compound's binding affinity for estrogen receptors (ER) while maintaining its collagen-binding ability. It was hypothesized that RAL-A would improve the mechanical integrity of bone in a manner similar to RAL, but with reduced estrogen receptor binding. Molecular assessment showed that while RAL-A did reduce ER binding, downstream ER signaling was not completely abolished. In-vitro, RAL-A performed similarly to RAL and had an identical concentration threshold on osteocyte cell proliferation, differentiation, and function. To assess treatment effect in-vivo, wildtype (WT) and heterozygous (OIM+/-) female mice from the Osteogenesis Imperfecta (OI) murine model were treated with either RAL or RAL-A from 8 weeks to 16 weeks of age. There was an untreated control group for each genotype as well. Bone microarchitecture was assessed using microCT, and mechanical behavior was assessed using 3-point bending. Results indicate that both compounds produced analogous gains in tibial trabecular and cortical microarchitecture. While WT mechanical properties were not drastically altered with either treatment, OIM+/- mechanical properties were significantly enhanced, most notably, in post-yield properties including bone toughness. This proof-of-concept study shows promising results and warrants the exploration of additional analog iterations to further reduce ER binding and improve fracture resistance

Simulation of the CTF drive beam line and comparison with the experiment

The tracking of particles in accelerating structures is presented for cases where the effects of the wake-fields are high. This is particularly the case when the structures are used with high current and relatively low energy as in the drive beam of the Compact Linear Collider Test Facility (CTF 2) with its 3 GHz accelerator and its 30 GHz decelerator. High initial energy spread and transverse wake-fields may impair the beam stability and generate particle loss. The CTF modelling is made with the code PARMELA for the 3 GHz part of the beam line, which includes 3 GHz accelerating sections and a magnetic bunch compressor. For the part containing the 30 GHz power-extracting structures, simulations are done with WAKE, a new algorithm dealing with the effects of the wake-field modes 0 and 1, as well as of the group velocity. Beam transmission through the overall beam line is studied, and results are compared with measurements made on the CTF beam

Dissipation Rate of Turbulent Kinetic Energy in Diel Vertical Migrations: Comparison of ANSYS Fluent Model to Measurements

Recent studies suggest that diel vertical migrations of zooplankton may have an impact on ocean mixing, though details are not completely clear. A strong sound scattering layer of zooplankton undergoing diel vertical migrations was observed in Saanich Inlet, British Colombia, Canada by Kunze et al. (2006). In this study, a shipboard 200- kHz echosounder was used to track vertical motion of the sound scattering layer, and microstructure profiles were collected to observe turbulence. An increase of dissipation rate of turbulent kinetic energy by four to five orders of magnitude was measured during diel vertical migrations of zooplankton in one case (but not observed during other cases). A strong sound scattering layer undergoing diel vertical migration was also observed in the Straits of Florida via a bottom mounted acoustic Doppler current profiler at 244 m isobath. A 3-D non-hydrostatic computational fluid dynamics model with Lagrangian particle injections (a proxy for migrating zooplankton) via a discrete phase model was used to simulate the effect of diel vertical migrations on the turbulence for both Saanich Inlet and the Straits of Florida. The model was initialized with idealized (but based on observation) density and velocity profiles. Particles, with buoyancy adjusted to serve as a proxy for vertically swimming zooplankton, were injected to simulate diel vertical migration cycles. Results of models run with extreme concentrations of particles showed an increase in dissipation rate of turbulent kinetic energy of approximately five orders of magnitude over background turbulence during migration of particles in both Saanich Inlet and the Straits of Florida cases (though direct relation of the turbulence produced by buoyant particles and swimming organisms isn’t straightforward). This increase was quantitatively consistent, with turbulence measurements by Kunze et al. (2006). When 10 times fewer particles were injected into the model, the effect on dissipation rate of turbulent kinetic energy was an order of magnitude smaller than that from the extreme concentration. At a concentration of particles 100 times smaller than the extreme concentration, there was no longer an observable effect. In the Straits of Florida, direct turbulence measurements were not available to make a quantitative comparison. However, a small, but statistically significant decrease in northward current velocity profiles during migration times were observed after averaging these profiles over 11 months. A small decrease of current velocity connected to the vertical migrations of particles was reproduced in the Straits of Florida model case. The deviations in the velocity profiles can be explained by the increase in turbulent mixing during vertical migration periods

Argentina’s Transition from Classic Neo-Liberal Policies to a Horizontal Autonomy From Riches to Rags: The Movement of Unemployed Workers

The purpose of this collection is to piece together a series of events in Argentina's history that resulted in the present day workers movements. Upon completion of an internship in Rosario, Argentina, an interest was sparked in learning more about the movements of unemployed workers through social autonomy. The economic crises that left hundreds of thousands unemployed were the beginnings to a revolution of horizontal‟ productivity, as hierarchical structures were eradicated. Through a chronological review of the political parties that ruled over the last century, several events are noteworthy in their impact of the current social, political, and economic organization of Argentina. The classical structure of neo-liberalism imposed during the 1980s and 1990s, had left a bitter taste in the mouths of the some 21 million impoverished individuals. With a set of economic policies imposed by monetary establishments like the International Monetary Fund (IMF) and the World Bank, neoliberalism offered affluence for the rich and paucity for the poor. In Argentina's case, countless suffered as privatization, deregulation and globalization led to the suppression of the nation's economy and the demise of the middle class. The result of such an economic catastrophe has encouraged workers to take matters into their own hands through a social movement known as Movimiento de Trabajadores Desocupados (MTD). Once abandoned factories are now fully occupied by former employees; however, this time without a hierarchical, management structure in place. Unions have formed to support participatory and democratic autonomy. The transition from a vertical to a horizontal structure of organization serves as the current trend in reclaimed factories. It is crucial to observe whether or not these structural changes are sound enough to withstand the political powers in play, as well as determine if they are beneficial to the nation's political economy