Particle-in-cell Simulations of Ion Dynamics in a Pinched-beam Diode

article-in-cell simulations of a 1.6 MV, 800 kA, and 50 ns pinched-beam diode have been completed with emphasis placed on the quality of the ion beams produced. Simulations show the formation of multiple regions in the electron beam flow characterized by locally high charge and current density (“hot spots”). As ions flow through the electron-space-charge cloud, these hot spots electrostatically attract ions to produce a non-uniform ion current distribution. The length of the cavity extending beyond the anode-to-cathode gap (i.e., behind the cathode tip) influences both the number and amplitude of hot spots. A longer cavity length increases the number of hot spots yet significantly reduces the amplitude producing a smoother, more uniform ion beam than for shorter cavities. The net current and the ion bending angles are also significantly smaller with long cavities

Carboxylic acids in clouds at a high-elevation forested site in central Virginia

During September 1990 we sampled coarse (>18-μm diameter) and fine (18- to 5.5-μm diameter) droplets and liquid-water content (LWC) in cloud from a tower on a forested ridge top in Shenandoah National Park, Virginia. Cloud-water pH and aqueous- and vapor-phase concentrations of carboxylic acids (HCOOH and CH3COOH) and formaldehyde (HCHO) were measured in parallel over 1- to 1.5-hour intervals. Both size fractions of cloud droplets contained similar concentrations of carboxylic species and H+ during most sampling; most cloud water was in coarse droplets. The pH of coarse (3.27–4.76) and fine (3.22–4.70) droplets coupled with total LWC of 0.04–0.56 g m−3 STP (standard m3 at 0°C and 1 atm) resulted in the partitioning of carboxylic acids primarily in the vapor phase. The observed phase partitioning for CH3COOH was within the uncertainty range of thermodynamic data. However, HCOOH exhibited significant phase disequilibria, which could not be explained by artifacts from variable LWC or from mixing droplets of different acidities. We hypothesize that the large volume of liquid water deposited on the forest canopy interacted with the near-surface cloud leading to apparent disequilibria based on time-integrated samples. HCOOH was selectively depleted relative to CH3COOH in cloud, particularly at higher pH, suggesting rapid removal of HCOOH by cloud-water deposition. We saw no evidence for significant production of HCOOH from the aqueous-phase oxidation of HCHO.Engineering and Applied Science

1962

Turf on the Launching Pad (page 1) Turf management Club News (3) Education, Experience and Attitude (4) A Blade of Grass (5) Picture - Professor Lawrence S. Dickinson (6) Picture - Thomas Mascaro - Banquet Speaker (7) Planting Trees on the Golf Course (8) Two-Way Radios (8) Greens Mowing Procedure (9) Watering and Topdressing as Related to Poa annua Infestations (10) Picture - Stockbridge Majors in Turf Management (12) Picture - Graduates of Winter School for Turf Managers - 1962 (13) Review of Season\u27s Pests by Joseph Troll (A-1) Today\u27s Trends in Golf Course Development by Col. Harry C. Eckoff (A-3) Breeding and Selection of Fine Turf Grasses by Dr. B. R. Anderson Penncross Bentgrass by J. Dutch(A-13) Poa annua by Alexander Radko (A-16) Velvet Bent by Jesse DeFrance (A-19) Vegetative Creeping Bentgrasses by Fred Grau (A-21) Modification of SOils for Green Construction & Top Dressing by Prof. H. B. Musser (A-27) Soil COmpaction by Donald Waddington (A-32) Irrigation Practices and the Need of Basic Research by Prof. Edward PIra (A-36) Water Sources by Z. Mills (A-39) Athletic Field Maintenance by Thomas Mascaro (A-41) Planning the Landscape Around the House by Prof. Harold Mosher (A-43

Carboxylic acids in the rural continental atmosphere over the eastern United States during the Shenandoah Cloud and Photochemistry Experiment

The Shenandoah Cloud and Photochemistry Experiment (SCAPE) was conducted during September 1990 in the rural continental atmosphere at a mountain top site (1014 m) in Shenandoah National Park, Virginia. We report here the extensive set of trace gas measurements performed during clear sky periods of SCAPE, with particular focus on the carboxylic acids, formic, acetic, and pyruvic. Median mixing ratios were 5.4 and 2.1 parts per billion by volume (ppbv) for formic and acetic acid, respectively, and they did not exhibit the diurnal variation characteristic of low-elevation sites. Mixing ratios of formic acid often approached or exceeded 10 ppbv, which are the largest values yet reported for the nonurban troposphere. Over the rural eastern United States, formic and acetic acid appear to have significant nonphotochemical sources. Secondary production from suspected pathways appears to be relatively unimportant. The observed lack of correlation between formic and acetic acid with peroxide species argues against a significant source from permutation reactions of peroxy radicals. In addition, model calculations using the SCAPE data indicate minimal production of carboxylics from olefin/O3 oxidation reactions. The tight correlation (r2 = 0.88) between mixing ratios of formic and acetic acid is strongly suggestive of a commonality in their sources. The seasonal cycle of carboxylic acids in the atmosphere and precipitation over the eastern United States is evidence that combustion emissions are not a principal source of these species. It appears that direct biogenic emissions from vegetation and soils cannot be ruled out as important sources. In particular, the correlation between the seasonal variation of formic and acetic acid and the ambient temperature is consistent with a soil microbial source. Similar conclusions were reached for pyruvic acid, with its mixing ratio ranging 4–266 parts per trillion by volume (pptv) (median = 63) and most likely supported by biogenic emissions and possibly photochemical sources.Engineering and Applied Science

Positive and negative effects of antipsychotic medication: an international online survey of 832 recipients

Background: Antipsychotic medication is currently the treatment of choice for psychosis, but few studies directly survey the first hand experience of recipients. Objectives: To ascertain the experiences and opinions of users of an international sample of antipsychotic drugs regarding positive and negative effects. Method: An online direct-to-consumer questionnaire was completed by 832 users of antipsychotics, from 30 countries – predominantly USA, UK and Australia. This is the largest such sample to date. Results: Over half (56%) thought the drugs reduced the problems they were prescribed for, but 27% thought they made them worse. Slightly less people found the drugs generally ‘Helpful’ (41%) than found them ‘Unhelpful’ (43%). While 35% reported that their ‘quality of life’ was ‘improved’, 54% reported that it was made ‘worse’. The average number of adverse effects reported was 11, with an average of five at the ‘severe’ level. Fourteen effects were reported by 57% or more participants, most commonly: ‘Drowsiness, feeling tired, sedation’ (92%), ‘Loss of motivation’ (86%), ‘Slowed thoughts’ (86%), and ‘Emotional numbing’ (85%). Suicidality was reported to be a side effect by 58%. Older people reported particularly poor outcomes and high levels of adverse effects. Duration of treatment was unrelated to positive outcomes but significantly related to negative outcomes. Most respondents (70%) had tried to stop taking the drugs. The most common reasons people wanted to stop were the side effects (64%) and worries about long-term physical health (52%). Most (70%) did not recall being told anything at all about side effects. Conclusions Clinical implications are discussed, with a particular focus on the principles of informed consent, and involving patients in decision making about their own lives

Protection of early phase hepatic ischemia-reperfusion injury by cholinergic agonists

BACKGROUND: Cytokine production is critical in ischemia/reperfusion (IR) injury. Acetylcholine binds to macrophages and inhibits cytokine synthesis, through the cholinergic anti-inflammatory pathway. This study examined the role of the cholinergic pathway in cytokine production and hepatic IR- injury. METHODS: Adult male mice underwent 90-min of partial liver ischemia followed by reperfusion. The AChR agonists (1,1-dimethyl-4-phenyl-L-pioperazinium-iodide [DMPP], and nicotine) or saline-vehicle were administered i.p. before ischemia. Plasma cytokine tumor necrosis factor (TNF)-α, macrophage inflammatory protein-2, and Interleukin-6 were measured. Liver injury was assessed by plasma alanine transaminase (ALT) and liver histopathology. RESULTS: A reperfusion time-dependent hepatocellular injury occurred as was indicated by increased plasma-ALT and histopathology. The injury was associated with marked elevation of plasma cytokines/chemokines. Pre-ischemic treatment of mice with DMPP or nicotine significantly decreased plasma-ALT and cytokines after 3 h of reperfusion. After 6 h of reperfusion, the protective effect of DMPP decreased and reached a negligible level by 24 h of reperfusion, despite significantly low levels of plasma cytokines. Histopathology showed markedly diminished hepatocellular injury in DMPP- and nicotine-pretreated mice during the early-phase of hepatic-IR, which reached a level comparable to saline-treated mice at late-phase of IR. CONCLUSION: Pharmacological modulation of the cholinergic pathway provides a means to modulate cytokine production and to delay IR-induced heaptocellular injury

Correlates of sunscreen use among high school students: a cross-sectional survey

Abstract Background Adolescents put themselves at risk of later skin cancer development and accelerated photo-aging due to their high rates of ultraviolet radiation exposure and low rates of skin protection. The purpose of the current study was to determine which of the Integrative Model constructs are most closely associated with sunscreen use among high school students. Methods The current study of 242 high school students involved a survey based on the Integrative Model including demographic and individual difference factors, skin protection-related beliefs and outcome evaluations, normative beliefs, self-efficacy, sunscreen cues and availability, intentions, and sunscreen use. Our analyses included multiple linear regressions and bootstrapping to test for mediation effects. Results Sunscreen use was significantly associated with female gender, greater skin sensitivity, higher perceived sunscreen benefits, higher skin protection importance, more favorable sunscreen user prototype, stronger skin protection norms, greater perceived skin protection behavioral control, and higher sunscreen self-efficacy. Intentions to use sunscreen mediated the relationships between most skin protection-related beliefs and sunscreen use. Conclusions The current study identified specific variables that can be targeted in interventions designed to increase sunscreen use among adolescents.</p

A genome-wide screen in human embryonic stem cells reveals novel sites of allele-specific histone modification associated with known disease loci

<p>Abstract</p> <p>Background</p> <p>Chromatin structure at a given site can differ between chromosome copies in a cell, and such imbalances in chromatin structure have been shown to be important in understanding the molecular mechanisms controlling several disease loci. Human genetic variation, DNA methylation, and disease have been intensely studied, uncovering many sites of allele-specific DNA methylation (ASM). However, little is known about the genome-wide occurrence of sites of allele-specific histone modification (ASHM) and their relationship to human disease. The aim of this study was to investigate the extent and characteristics of sites of ASHM in human embryonic stem cells (hESCs).</p> <p>Results</p> <p>Using a statistically rigorous protocol, we investigated the genomic distribution of ASHM in hESCs, and their relationship to sites of allele-specific expression (ASE) and DNA methylation. We found that, although they were rare, sites of ASHM were substantially enriched at loci displaying ASE. Many were also found at known imprinted regions, hence sites of ASHM are likely to be better markers of imprinted regions than sites of ASM. We also found that sites of ASHM and ASE in hESCs colocalize at risk loci for developmental syndromes mediated by deletions, providing insights into the etiology of these disorders.</p> <p>Conclusion</p> <p>These results demonstrate the potential importance of ASHM patterns in the interpretation of disease loci, and the protocol described provides a basis for similar studies of ASHM in other cell types to further our understanding of human disease susceptibility.</p

Phenotypic expansion in DDX3X - a common cause of intellectual disability in females

De novo variants in DDX3X account for 1-3% of unexplained intellectual disability (ID) cases and are amongst the most common causes of ID especially in females. Forty-seven patients (44 females, 3 males) have been described. We identified 31 additional individuals carrying 29 unique DDX3X variants, including 30 postnatal individuals with complex clinical presentations of developmental delay or ID, and one fetus with abnormal ultrasound findings. Rare or novel phenotypes observed include respiratory problems, congenital heart disease, skeletal muscle mitochondrial DNA depletion, and late-onset neurologic decline. Our findings expand the spectrum of DNA variants and phenotypes associated with DDX3X disorders