Development Of Third Harmonic Generation As A Short Pulse Probe Of Shock Heated Material

We are studying high-pressure laser produced shock waves in silicon (100). To examine the material dynamics, we are performing pump-probe style experiments utilizing 600 ps and 40 fs laser pulses from a Ti:sapphire laser. Two-dimensional interferometry reveals information about the shock breakout, while third harmonic light generated at the rear surface is used to infer the crystalline state of the material as a function of time. Sustained third harmonic generation (THG) during a similar to 100 kbar shock breakout indicate that the rear surface remains crystalline for at least 3 ns. However, a decrease in THG during a similar to 300 kbar shock breakout suggests a different behavior, which could include a change in crystalline structure.Mechanical Engineerin

Depression, School Performance, and the Veridicality of Perceived Grades and Causal Attributions

An external criterion was assessed to test whether depressives have distorted perceptions of covariation information and whether their attributions are consistent with this information. Students’ actual and self-perceived grades, depression status, and attributions for failures were assessed. Furthermore, partici pants estimated average grades. Generally, self-perceived own past grades were inflated. Depressed students and those with low grades distorted their own grades (but not the average grade) more to their favor than individuals low in depression and those with high grades. Depression went along with lower actual grades and with internal, stable, and global failure attributions. Mood differences in attributions were not due to differences in previous grades. Depressed individuals drew (unrealistically) more depressogenic causal inferences when they perceived average grades to be low than when average grades were perceived to be high. However, they (realistically) attributed failure more in a depressogenic fashion than did nondepressives when their own grade history was low

Energy Efficiency Ratios of Surface Mining Systems for a Small Iowa Coal Mine

The normal criterion used to determine if a mining venture should be started or continued is its financial profitability. Energy efficiency is another criterion for dealing with public energy decisions. The energy efficiency ratios (output/input) of a large bulldozer, a scraper ripper, a small dragline, and a large dragline system were calculated for the Iowa Coal Project Demonstration Mine #1 (ICPDM #1) located between Oskaloosa and Bussey, Iowa. Even though the large dragline had the lowest cost and highest energy efficiency, it would not be used on this site without having other nearby sites available to allow long-term use

On the Properties of Plastic Ablators in Laser-Driven Material Dynamics Experiments

Radiation hydrodynamics simulations were used to study the effect of plastic ablators in laser-driven shock experiments. The sensitivity to composition and equation of state was found to be 5-10% in ablation pressure. As was found for metals, a laser pulse of constant irradiance gave a pressure history which decreased by several percent per nanosecond. The pressure history could be made more constant by adjusting the irradiance history. The impedance mismatch with the sample gave an increase o(100%) in the pressure transmitted into the sample, for a reduction of several tens of percent in the duration of the peak load applied to the sample, and structured the release history by adding a release step to a pressure close to the ablation pressure. Algebraic relations were found between the laser pulse duration, the ablator thickness, and the duration of the peak pressure applied to the sample, involving quantities calculated from the equations of state of the ablator and sample using shock dynamics.Comment: Typos fixe

Operation Moshtarak and the manufacture of credible, “heroic” warfare

Richard Lance Keeble argues that Fleet Street’s coverage of the Afghan conflict has served largely to promote the interests of the military/industrial/media complex – and marginalise the views of the public who have consistently appealed in polls for the troops to be brought back hom

AN AUTOREGRESSION MODEL FOR A PAIRED WATERSHED COMPARISON

Analysis of water quality data from a paired watershed design is needed to determine if a best fertilizer management practice reduces a specific water quality variable compared to a conventional fertilizer management practice. This study examines an existing recommended method of analysis for paired watershed designs, simple analysis of covariance (ANCOVA) on time aggregated data, then offers two autoregression analyses (AR) as alternatives. The first approach models the sequence of paired differences and estimates its 95% confidence band. The second approach develops individual watershed AR models then examines the joint 95% confidence interval about the predicted difference. A reliability analysis on the water quality data reveals that the data for the controlled watershed, i.e., the covariate, has a sizable measurement error, a factor that is not considered in the usual ANCOVA model. The AR methods avoid the measurement error and other inherent problems with the published recommended method. Graphically both AR analyses are similar and reveal three distinct trend phases: a period of continued similarity; a period of transition; and a period of sustained change. The model for the sequence of paired differences is the easier one of the two AR methods to use and interpret because its trend model of splined linear segments readily defines each response phase. Hence, we recommend it over the given alternatives. It offers water resources researchers an effective and readily adoptable analysis option

Firefighters Versus Law Enforcement Officers: A Comparison Of Cardiovascular Disease Risk

Firefighters (FF) and law enforcement officers (LEO) have heightened cardiovascular disease (CVD) risk due to the stressful nature of their occupations. Data suggest that 45% of on-duty FF fatalities are related to CVD, while LEO have a 1.7 times higher CVD prevalence compared to the general public. To our knowledge, studies comparing FF to LEO, in terms of CVD risk factors, have not been published. This information is necessary to better understand differences in occupational disease risk, as well as to help bridge the gap between stress and CVD markers. PURPOSE: To compare CVD risk biomarkers, fitness, and body composition between career FF and LEO. METHODS: Ninety-eight career, structural male FF (age = 35.1±9.6 yrs; weight = 94.3±15.4 kg; height = 178.4±13.2 cm) and seventy-three career male and female LEO (age = 41.4±9.0 yrs; weight = 92.3±16.8 kg; height = 179.6±8.1 cm) from local fire and police departments were studied. Participants completed a maximal cardiopulmonary exercise test (CPXT), where VO2max was estimated from the Foster equation. Fasted blood samples were collected to assess biomarkers of CVD risk: advanced oxidation protein products (AOPP) and cortisol. Dual-energy X-ray absorptiometry was used to assess body composition and waist and hip measures were taken. Shapiro-Wilk Test was used to assess normality. Independent sample T-tests or non-parametric Mann-Whitney U tests (if normality was violated) were used to assess differences in CVD risk biomarkers, fitness, and body composition between the FF and LEO. Effect sizes were calculated as Cohen’s d (i.e., small [0.2-0.5], medium [0.5-0.8], large [\u3e0.8]). RESULTS: Firefighters had higher (p\u3c0.05) CPXT exercise times (FF: 10.9±1.6 min; LEO: 10.3±2.0 min; d=0.366) compared to LEO. While not statistically significant (p=0.64), FF had higher VO2max values (FF: 38.2±6.6 ml/kg/min; LEO: 36.2±6.2 ml/kg/min; d=0.306). Firefighters also had higher (p\u3c0.05) AOPP (FF: 134.8±90.1 mM; LEO: 106.8±67.6 mM; d=0.342), blood cortisol (FF: 14.2±5.0 mg/dL; LEO: 12.5±5.6 mg/dL; d=0.325), and waist-to-hip ratios (FF: 0.95±0.06; LEO: 0.89±0.08; d=0.792). CONCLUSION: These findings suggest that while FF demonstrated greater CPXT time-to-exhaustion they also expressed greater levels of stress and risk for CVD compared to LEO

A wide-spectrum language for verification of programs on weak memory models

Modern processors deploy a variety of weak memory models, which for efficiency reasons may (appear to) execute instructions in an order different to that specified by the program text. The consequences of instruction reordering can be complex and subtle, and can impact on ensuring correctness. Previous work on the semantics of weak memory models has focussed on the behaviour of assembler-level programs. In this paper we utilise that work to extract some general principles underlying instruction reordering, and apply those principles to a wide-spectrum language encompassing abstract data types as well as low-level assembler code. The goal is to support reasoning about implementations of data structures for modern processors with respect to an abstract specification. Specifically, we define an operational semantics, from which we derive some properties of program refinement, and encode the semantics in the rewriting engine Maude as a model-checking tool. The tool is used to validate the semantics against the behaviour of a set of litmus tests (small assembler programs) run on hardware, and also to model check implementations of data structures from the literature against their abstract specifications

Physiological Stress Responses to a Live-Fire Training Evolution in Career Firefighters

Firefighters have a physically demanding job that exposes them to many specific and unique stressors, which contribute to cardiovascular disease (CVD) risk (i.e., cardiovascular strain, inflammation, and oxidative stress) or even mortality. At present, the literature lacks data evaluating these physiological stress responses amongst firefighters in any realistic or simulated scenarios, such as a live-fire training evolution (LFTE). Given the elevated risk of premature mortality, there is a critical need to better understand the physiological stress responses to an LFTE. This information could aid in developing nutritional, training, and other various interventions to mitigate stress load and reduce the incidence of CVD among this population. PURPOSE: To assess the physiological stress response to an LFTE among firefighters. METHODS: Seventy-six (n = 76) career firefighters completed an LFTE. Salivary samples were collected pre, immediately post, and 30-min post the LFTE, and analyzed the following stress markers: α-amylase (AA), secretory immunoglobulin-A (SIgA), and cortisol. One-way repeated measures analysis of variance was used to assess changes over time. Fisher’s LSD and Cohen’s d effect size calculations were used for Post hoc analysis. RESULTS: Significant main effects for time were found for AA, SIgA, and cortisol (p\u3c0.001). Fisher’s LSD post hoc analysis found AA, SIgA, and cortisol concentrations were all significantly elevated immediately post LFTE compared to pre (p\u3c0.0001) and 30-min post (p\u3c0.0001). Medium to large effect sizes were noted for AA, SIgA, and cortisol with respect to changes pre to immediately post-LFTE (d = 0.84, 0.61, and 0.78, respectively). CONCLUSION: While many studies have shown increased inflammation and oxidative stress, as well as adverse cardiovascular and metabolic responses to firefighting activities, these data provide insight into the physiological stress placed upon a firefighter engaging in fire-suppressive evolutions

Mechanically Stabilized Tetrathiafulvalene Radical Dimers

Two donor−acceptor [3]catenanes—composed of a tetracationic molecular square, cyclobis(paraquat-4,4′-biphenylene), as the π-electron deficient ring and either two tetrathiafulvalene (TTF) and 1,5-dioxynaphthalene (DNP) containing macrocycles or two TTF-butadiyne-containing macrocycles as the π-electron rich components—have been investigated in order to study their ability to form TTF radical dimers. It has been proven that the mechanically interlocked nature of the [3]catenanes facilitates the formation of the TTF radical dimers under redox control, allowing an investigation to be performed on these intermolecular interactions in a so-called “molecular flask” under ambient conditions in considerable detail. In addition, it has also been shown that the stability of the TTF radical-cation dimers can be tuned by varying the secondary binding motifs in the [3]catenanes. By replacing the DNP station with a butadiyne group, the distribution of the TTF radical-cation dimer can be changed from 60% to 100%. These findings have been established by several techniques including cyclic voltammetry, spectroelectrochemistry and UV−vis−NIR and EPR spectroscopies, as well as with X-ray diffraction analysis which has provided a range of solid-state crystal structures. The experimental data are also supported by high-level DFT calculations. The results contribute significantly to our fundamental understanding of the interactions within the TTF radical dimers