cssi/SciSciGPT-SciSciNet huggingface dataset:
Secondary electron emission from reticulated cellular copper surfaces

An experimental and computational study of the secondary electron yield (SEY) of copper foam is presented. Ray-tracing Monte Carlo (MC) simulations, based on primary electron transport and interactions with the electron system in solid and foam-type copper, are also included. The 3D reticulated foam geometry is explicitly represented in the MC model. This allows the influence of the complex copper surface on the energy and angular dependence of the SEY to be determined. Experimental measurements of SEY were performed in a high-vacuum electron gun chamber. Solid copper and copper foam with 100 pores per inch and a 4.6% volume fraction were tested for energy and angular dependence of SEY. Incident angles were varied from 0 ° to 75 ° and electron beam energy ranged from 20 eV to 570 eV. The agreement between MC simulations and experiments suggests that a general reduction of the SEY by around 20% is due to the interaction and subsequent adsorption of a fraction of emitted secondary electrons on the internal surfaces of the reticulated foam. Moreover, it is found that the SEY becomes nearly independent of the incident electron energy above 200 eV for steep angles of incidence ( θ > 45 °).
Experiences of a Health System's Faculty, Staff, and Trainees' Career Development, Work Culture, and Childcare Needs During the COVID-19 Pandemic.

Importance: In March 2020, US public buildings (including schools) were shut down because of the COVID-19 pandemic, and 42% of US workers resumed their employment duties from home. Some shutdowns remain in place, yet the extent of the needs of US working parents is largely unknown. Objective: To identify and address the career development, work culture, and childcare needs of faculty, staff, and trainees at an academic medical center during a pandemic. Design, Setting, and Participants: For this survey study, between August 5 and August 20, 2020, a Qualtrics survey was emailed to all faculty, staff, and trainees at University of Utah Health, an academic health care system that includes multiple hospitals, community clinics, and specialty centers. Participants included 27â¯700 University of Utah Health faculty, staff, and trainees who received a survey invitation. Data analysis was performed from August to November 2020. Main Outcomes and Measures: Primary outcomes included experiences of COVID-19 and their associations with career development, work culture, and childcare needs. Results: A total of 5030 participants completed the entire survey (mean [SD] age, 40 [12] years); 3738 (75%) were women; 4306 (86%) were White or European American; 561 (11%) were Latino or Latina (of any race), Black or African American, American Indian, Alaska Native, and Native Hawaiian or Pacific Islander; and 301 (6%) were Asian or Asian American. Of the participants, 2545 (51%) reported having clinical responsibilities, 2412 (48%) had at least 1 child aged 18 years or younger, 3316 (66%) were staff, 791 (16%) were faculty, and 640 (13%) were trainees. Nearly one-half of parents reported that parenting (1148 participants [49%]) and managing virtual education for children (1171 participants [50%]) were stressors. Across all participants, 1061 (21%) considered leaving the workforce, and 1505 (30%) considered reducing hours. Four hundred forty-nine faculty (55%) and 397 trainees (60%) perceived decreased productivity, and 2334 participants (47%) were worried about COVID-19 impacting their career development, with 421 trainees (64%) being highly concerned. Conclusions and Relevance: In this survey of 5030 faculty, staff, and trainees of a US health system, many participants with caregiving responsibilities, particularly women, faculty, trainees, and (in a subset of cases) those from racial/ethnic groups that underrepresented in medicine, considered leaving the workforce or reducing hours and were worried about their career development related to the pandemic. It is imperative that medical centers support their employees and trainees during this challenging time.
Verifying Clinically Derived Reference Intervals for Daily Excretion Rates of Fractionated Metanephrines Using Modern Indirect Reference Interval Models.

Objectives Biochemical testing of urinary metanephrines is useful in the diagnosis and monitoring of pheochromocytoma and paragangliomas. We investigated the feasibility of mixture decomposition (ie, indirect) methods in verifying clinically derived reference intervals for urinary deconjugated metanephrine metabolites. Methods Urinary 24-hour metanephrine and normetanephrine excretion results were extracted from our data warehouse and intervals were estimated by the modern variant of the Hoffmann method, maximum likelihood estimation (MLE), and gamma mixture model using R software. Results Hoffmann, MLE, and gamma mixture models provided metanephrine and normetanephrine intervals that closely matched those derived from clinical studies. However, three-component MLE and gamma models were required for normetanephrine in adult women because the Hoffmann method was not suitable. Some data transformations caused blending of the mixed distributions and subsequent widening of the reference interval estimation, emphasizing the importance of careful data transformation for Hoffmann and MLE analyses. Gamma mixture models gave overall good agreement without the need for data transformation. Conclusions Indirect methods have utility in verifying reference intervals in 24-hour urine specimens collected by patients. We emphasize the benefits of applying multiple decomposition methods to corroborate findings and careful application of data transformation when using Gaussian-based models.
Multi-label classification with local pairwise and high-order label correlations using graph partitioning

Abstract In multi-label learning problems, the class labels are correlated and the label correlations can be leveraged to improve the predictive performance of a classifier. Methods that consider high-order correlations in the label space, usually do not utilize pairwise correlations. In most of these methods, label correlations are considered as prior knowledge, which can be misleading in problems with noisy or missing labels. In such cases, learning the label correlation as part of the model training task is more effective. In this paper, a rule-based evolutionary multi-label classification method is proposed that incorporates the local label correlations through the high-order label subsets and pairwise dependencies. Graph structures are employed to model the label dependencies and the estimated label similarities are used to obtain more accurate label sets for the classification rules. To refine the high-order label relations, a novel hierarchical density-based clustering method is proposed to obtain a k -way partitioning for the label graphs based on their pairwise correlations. The effectiveness of the proposed method is experimented on multiple benchmark datasets from different domains and compared with several well-known multi-label classification algorithms. The proposed method has shown the highest average rank along multiple metrics and the results are consistently better than or similar to the compared methods with statistical significance.
Sequential Monte Carlo Methods in the nimble and nimbleSMC R Packages

nimble is an R package for constructing algorithms and conducting inference on hierarchical models. The nimble package provides a unique combination of flexible model specification and the ability to program model-generic algorithms. Specifically, the package allows users to code models in the BUGS language, and it allows users to write algorithms that can be applied to any appropriate model. In this paper, we introduce the nimbleSMC R package. nimbleSMC contains algorithms for state-space model analysis using sequential Monte Carlo (SMC) techniques that are built using nimble. We first provide an overview of state-space models and commonly-used SMC algorithms. We then describe how to build a state-space model in nimble and conduct inference using existing SMC algorithms within nimbleSMC. SMC algorithms within nimbleSMC currently include the bootstrap filter, auxiliary particle filter, ensemble Kalman filter, IF2 method of iterated filtering, and a particle Markov chain Monte Carlo (MCMC) sampler. These algorithms can be run in R or compiled into C++ for more efficient execution. Examples of applying SMC algorithms to linear autoregressive models and a stochastic volatility model are provided. Finally, we give an overview of how model-generic algorithms are coded within nimble by providing code for a simple SMC algorithm. This illustrates how users can easily extend nimble's SMC methods in high-level code.
Disparities in the Treatment and Survival of Metastatic Renal Cell Carcinoma.

Objectives To evaluate racial, gender, and socioeconomic differences in the treatment of metastatic renal cell carcinoma (mRCC) and their impact on survival. Methods Patients aged ≥18 years diagnosed with mRCC in the National Cancer Database (2004-2015) were analyzed. Multivariable logistic regression models were used to evaluate factors associated with systemic therapy and CN utilization. Cox proportional hazards regression models were used to evaluate overall survival. Results In total, 31,989 patients with mRCC were identified with 30.2% receiving CN, 51.6% receiving systemic therapy, and 25.8% receiving no treatment. Females were at lower odds of receiving systemic therapy (OR 0.91, p Conclusions There are racial, gender, and socioeconomic differences in the treatment of mRCC which are associated with a disparity in overall survival. Dismantling systemic barriers and improving access to care may lead to reduced disparities and improved outcomes for mRCC.
Genetics and Molecular Biology of Higher Plant Nitrate Reductases

Nitrate assimilation is the primary pathway through which most reduced nitrogen is accumulated in plants. The pathway consists of two well characterized enzymes, nitrate and nitrite reductases. Poorly characterized nitrate uptake and transport mechanisms are also involved. Nitrate reductase (NR) catalyzes the reduction of nitrate to nitrite which is then reduced to ammonium ion by nitrite reductase. Incorporation of ammonium ion into amino acids is carried out by the glutamine synthetaseglutamate synthase pathway. The first step in the nitrate assimilation pathway, nitrate reductase, is highly regulated and is believed to be rate limiting. There has been a great deal of research concerning the biochemistry, genetics and physiology of NR which has recently been reviewed.1–3 Also a recent comprehensive conference was held on the topic of nitrate assimilation, and the proceedings will be published.4 Readers are referred to these works and the references therein for a detailed review. Here we will concentrate on NR, especially the recent accomplishments.
Images, Ideology, and Praxis in the Environmental Movement: Sebastião Salgado’s Genesis Project

This article is part of a panel discussion addressing the sociological relevance of Sebastiao Salgado's work as well as documentary photography in general. 2 I focus specifically on environmental sociology.
A hydroinformatician's approach to computational innovation and the design of genetic algorithms

The paper discusses how a computational hydralician got involved in the design, implementation, and application of genetic algorithms – search procedures based on the mechanics of natural selection and genetics – and how that involvement depended critically upon the modern hydroinformatician’s sense of appropriate modeling of complex phenomena such as fluid mechanics. The paper starts by briefly reviewing the mechanics of genetic algorithms and then connects that mechanics to the fundamental intuition that GAs have something in common with human innovative processes. The paper continues with a short aside on a difference in the way hydroinformaticians and computer scientists are taught to reason with models. This leads to a discussion of the race between selection and recombination in a GA, and how understanding the race leads immediately to the construction of a critical dimensionless quantity in GA analysis. This dimensionless quantity is then sketched in the GA’s control map , and the paper concludes with a brief discussion of how such knowledge leads to the design of competent GAs – GAs that solve hard problems, quickly, reliably, and accurately. The paper concludes with an invitation to hydroinformaticians to both use genetic algorithms in the solution of difficult hydroinformatics problems and to apply their analytical skill to the design of ever more capable genetic and evolutionary algorithms.
Democracy for Money: Impact of Western Financial Aid on Democratic Consolidation in Eastern Europe and Eurasia

This paper analyzes the impact of Western financial assistance on democratic consolidation in the post-communist countries of Eastern Europe and Eurasia. In contrast to the prior research results indicating that external aid seldom results either in economic growth or democratic development, the present study establishes a strong correlation between the amounts and destinations of assistance on the one hand, and the strengthening of democracy indices on the other. This finding might point at an exceptional character of transition in Eastern Europe and is explained by the outstanding importance of the region from the viewpoint of the donors’ geostrategic interests. It equally implies that the West allocated aid selectively and welcomed only the chosen few into the elite club of prosperous democratic nations and the North Atlantic zone of peace.
Phase transitions in sampling algorithms and the underlying random structures

Sampling algorithms based on Markov chains arise in many areas of computing, engineering and science. The idea is to perform a random walk among the elements of a large state space so that samples chosen from the stationary distribution are useful for the application. In order to get reliable results, we require the chain to be rapidly mixing, or quickly converging to equilibrium. For example, to sample independent sets in a given graph G, the so-called hard-core lattice gas model, we can start at any independent set and repeatedly add or remove a single vertex (if allowed). By defining the transition probabilities of these moves appropriately, we can ensure that the chain will converge to a use- ful distribution over the state space Ω. For instance, the Gibbs (or Boltzmann) distribution, parameterized by Λ>0, is defined so that p(Λ)=π(I)=Λ|I| /Z, where $Z = \sum_{J \in \Omega} \Lambda^{|J|}$ is the normalizing constant known as the partition function. An interesting phenomenon occurs as Λ is varied. For small values of Λ, local Markov chains converge quickly to stationarity, while for large values, they are prohibitively slow. To see why, imagine the underlying graph G is a region of the Cartesian lattice. Large independent sets will dominate the stationary distribution π when Λ is sufficiently large, and yet it will take a very long time to move from an independent set lying mostly on the odd sublattice to one that is mostly even. This phenomenon is well known in the statistical physics community, and characterizes by a phase transition in the underlying model.
Synthesis of macromolecules in epithelial cells of the cultured amphibian lens: I. DNA and RNA

Abstract 1. 1. When bullfrog lenses are introduced into a culture system, the epithelial cells undergo bursts of DNA synthesis and mitosis which reach peaks at 52 and 87 hr post-isolation, respectively. 2. 2. These events are preceded by an augmentation of RNA synthesis which begins within 10 hr of isolation and attains peaks at 36 and 72 hr. 3. 3. If the increment in RNA synthesis is blocked by treatment with 10 −1 μg/ml actinomycin D the waves of DNA synthesis and mitosis are suppressed even though uridine incorporation in “blocked” lenses is still significantly higher than it is in freshly isolated material. 4. 4. It was shown by autoradiographic means that when the actinomycin D was supplied in tritiated form it was incorporated almost exclusively into the nucleus. 5. 5. The foregoing results were discussed with reference to the mechanisms which control proliferation.
Mental and Physical Health Consequences of the September 11, 2001 (9/11) Attacks in Primary Care: A Longitudinal Study

The attacks of September 11, 2001 (9/11) were unprecedented in their devastation, resulting in almost 3,000 fatalities and extensive environmental damage. The magnitude of the destruction is widely believed to have had an immediate as well as long-term impact on mental and physical health (Norris et al., 2002). Yet, only few studies have assessed longitudinally the effects of the 9/11 attacks on mental and physical health of exposed individuals. In the general population, the mental health effects of the 9/11 attacks appear to decline with the passage of time (Neria, DiGrande, & Adams, 2011). In one nationally representative study, the proportion of adults reporting posttraumatic stress disorder (PTSD) declined from 17% after 2 months to 5.8% after 3 months following the attacks (Holman, Silver, McIntosh, Poulin, & Gil-Rivas, 2008). In representative samples of adults residents in New York City (NYC), the prevalence of PTSD fell from 7.5% one month after the attacks to 1.7% at 4 months and to less than 1% 6 months after 9/11 (Galea et al., 2003). In a mid-term longitudinal survey of adults living in NYC, prevalence of PTSD declined from 5.0% at 1 year after 9/11 to 3.8% at 2 years after the attacks (Adams & Boscarino, 2006). Several adverse physical health effects have been documented due to exposure to irritant dust, smoke, and gaseous combustion materials. Respiratory (Brackbill et al., 2009; Lin, Jones, Reibman, Morse, & Hwang, 2010) and cardiovascular (Holman et al., 2008) problems markedly increased following the attacks, with more modest increases of gastroesophageal reflux, obesity, sleep apnea, and dermatological conditions (Green et al., 2006). However, much of the research on post-9/11 physical health outcomes is limited to cross-sectional design or short-term follow-up data and few medical outcomes. Moreover, despite increasing evidence that urban and ethnic populations are at increased risk for a range of disaster-induced mental health problems (e.g., Norris et al., 2002), only few studies to date have studied urban primary care populations exposed to mass trauma (Neria et al., 2006, 2008, 2010). To address these gaps in knowledge, the current study sought to assess a range of mental, physical, functional, and service utilization outcomes, 1 and 4 years after 9/11, and examine their longitudinal course and associations with 9/11 exposure to trauma (direct and indirect) and loss separately in a cohort of urban primary care patients in northern Manhattan. We hypothesized that (a) the rates of mental disorders would exceed previously reported rates of these disorders in the community due to the demographic characteristics of this cohort; (b) rates of mental, physical, functional, and service utilization outcomes would decline over time; and (c) patients who experienced direct exposure or 9/11 loss would exhibit worse mental and physical health outcomes compared to indirectly exposed patients.
El impulso, el recogimiento, el antídoto

Whitman, Dickinson, Williams. Tres poetas norteamericanos / A proposito de Whitman, Dickinson, Williams y su obra. Traduccion y seleccion de J.M. Arango Editorial Norma, Coleccion Cara y Cruz, Bogota, 1991.
Surgical experiences and training of residents: perspective of experienced gynecologic oncologists.

Abstract Objective. The aim of this study was to report the opinions of experienced gynecologic oncologists concerning the surgical education and experiences of residents. Methods. The 1997 membership directory of the Society of Gynecologic Oncologists was used to identify individuals who were members for at least 5 years and on the faculty of residency training programs. One hundred seventy members were identified and a nine-question survey was mailed to them. Results. One hundred nineteen (70%) surveys were returned. One hundred seventeen individuals were on the faculty of residency training programs and involved in the surgical training of residents. Ninety-six percent reported that gynecologic oncologists were a major resource for surgical education at their institution. Eight-nine (76%) reported a change in the volume of major abdominal and vaginal surgical procedures performed for noninvasive disease over the past 5 years. Of these 89, 16 (18%) reported that surgical volume at their institution decreased by 10%, 38 (43%) reported that surgical volume decreased by 10–25%, and 17 (19%) reported that surgical volume decreased by more than 25%. Sixty-three percent of all respondents reported that residents were not as well versed in pre- and postoperative care when compared to those of 5 years ago. Sixty-five percent of all respondents reported that graduating residents were less prepared in surgical techniques when compared to those of 5 years ago. Seventy-five percent of respondents reported that the primary care requirements of the RRC have decreased the amount of surgical experience, ICU rotations, and anesthesia rotations. Sixty percent of all respondents operated with other attending surgeons on more difficult cases, and 29% had changed to this practice within the past 5 years. Eighty-two percent believed that more time during residency training needs to be devoted gynecologic surgical experience. Conclusions. Experienced gynecologic oncologists on the faculty of residency training programs report a decrease in surgical skills and surgical experiences when compared to residents trained 5 years ago.
Earth science: A wet mantle conductor?

Arising from: X. Huang, Y. Xu & S. Karato Nature 434, 746–749 (2005); Huang et al. reply The suggestion that the transition zone of Earth's mantle (410–670 km in depth) is enriched in water is of great possible significance to the geodynamics and geochemistry of Earth's interior, as well as for the role of the mantle in the global water cycle1. Huang et al.2 compare the effect of water on electrical conductivities of transition-zone phases to electromagnetic and magnetotelluric soundings of the mantle beneath the North Pacific3 and conclude that the transition zone contains between 1,000 and 2,000 p.p.m. of water, which is considerably more than the 50–200 p.p.m. present in the upper mantle4,5,6. This conclusion is predicated on the assumption that the transition zone is relatively oxidized, but in fact fairly reduced conditions are more likely7,8. Here I show that if the transition zone is reduced, high conductivities can be explained without the requirement for large enrichments of water.
Verifying properties of parallel programs: an axiomatic approach

An axiomatic method for proving a number of properties of parallel programs is presented. Hoare has given a set of axioms for partial correctness, but they are not strong enough in most cases. This paper defines a more powerful deductive system which is in some sense complete for partial correctness. A crucial axiom provides for the use of auxiliary variables, which are added to a parallel program as an aid to proving it correct. The information in a partial correctness proof can be used to prove such properties as mutual exclusion, freedom from deadlock, and program termination. Techniques for verifying these properties are presented and illustrated by application to the dining philosophers problem.
Causes of death in marine mammals stranded along the Oregon coast.

Sixty-eight marine mammals stranded on the Oregon beaches were examined at necropsy. Gunshot was the primary cause of death in 30% of the pinnipeds examined. Bacterial infections (27%) and parasitism (27%) were also of major importance in the death and debilitation of Oregon marine mammals. Traumatic death or debilitation other than gunshot was observed in 11 animals(16%). Predation, starvation due to neonatal abandonment, viral encephalitis (presumptive diagnosis), dystocia and neoplasia were diagnosed as primary or contributory causes of stranding.
Uptake of [14C]urea by the in vivo choroid plexus—cerebrospinal fluid—brain system: identification of sites of molecular sieving

1. The time course of the uptake of [14C]urea by the lateral ventricular choroid plexus of the adult rat in vivo was analysed to delineate further the permeability characteristics of the epithelial membrane of this secretory tissue. 2. Eight hours after I.P. injection, [14C]urea attained a steady-state distribution in 78% of the tissue water of lateral ventricular choroid plexus; similarly, approximately 8 hr was required for radiourea to reach a steady-state concentration in both the cerebral cortex and cerebrospinal fluid (c.s.f.). 3. Results obtained for compartment analysis were used to calculate the concentration of [14C]urea in the epithelium of the lateral ventricular plexus during the approach to and at steady-state distribution. Even after 1 hr of distribution, the [14C]urea concentration in choroid cell water was less than 15% of that in plasma water. 4. Although the concentration of radiourea in choroid cell water continually increased after 3 hr, it remained in equilibrium with the concentration of [14C]urea in c.s.f. water. At the steady state (i.e., 8 hr), the distribution of [14C]urea between the water of plasma and that of the choroidal epithelium was considerably away from equilibrium (i.e., by 25-30%). 5. An analysis of the concentration gradients for [14C]urea across both the apical (c.s.f.-facing) and basolateral (plasma-facing) membranes of the epithelium of the lateral ventricular plexus suggests that the movement of urea is hindered to a greater extent by the basolateral membrane than by the apical membrane. 6. Only a single half-time component (1·3 hr) can be resolved from analysis of the curve describing the time course of uptake of radiourea by the choroid epithelial cell compartment. 7. The concentration gradient data suggest that urea penetrates from blood to c.s.f. via the choroid plexus by a transcellular pathway; however, it is not possible to rule out a paracellular pathway for urea movement. 8. At the steady state, radiourea distributes into 88% of the water of cerebral cortex. This observation, together with the finding of a steady-state concentration gradient for [14C]urea from cortical tissue to c.s.f., constitutes evidence that urea movement is hindered at the blood-brain barrier as well as at the blood—c.s.f. barrier.
Spatial Patterns in Autotrophic Picoplankton Abundance in a Reservoir Examined Using Microcosm Experiments

Autotrophic picoplankton (APP) are critically important in the production of organic matter in plankton food webs, A number of obvious environmental factors, including light, temperature, nutrient concentrations, and predation, have been identified as influencing APP abundance and growth rates. However, few experiments have investigated more than one factor at a time for their relationships to APP abundance or growth rate. We conducted a series of single and multi-factor experiments to examine the relative importance of several biotic and abiotic variables, and their interactions, for their effects on APP abundance and growth rates. Experiments were conducted using APP samples collected during summer from the riverine and lacustrine zones of a southeastern U.S. reservoir. Growth rates of APP responded rapidly to nutrient addition, but the magnitude of the response was dependent on location of collection, and on the presence of grazers and other phytoplankton. Growth rates of APP from the riverine zone were limited by nitrogen, whereas lacustrine zone APP responded positively to both phosphorus and nitrogen addition. Regulation of APP population size by heterotrophic nanoflagellates appeared to be most effective when APP growth rates were relatively slow. APP cell chlorophyll concentrations varied inversely with the percentage of surface light in the mixed layer of the reservoir. We suggest that due to spatial differences in the rate and depth of vertical mixing, lacustrine zone APP receive less light on average, or light at less frequent intervals, than APP in the more turbid but shallower riverine zone. Longitudinal declines in both nutrient and light availability during summer may reduce APP growth rates and population size in the lacustrine zone compared to the more productive riverine zone of this reservoir.
A microprocessor-controlled laser grating system for laser tuning

Abstract An apparatus for tuning a laser system to different wavelengths has been developed. The controlling electronics consists of a microprocessor and stepper motor combination utilized to control the angular position of a laser cavity grating. A resolution of 0.09° per step has been obtained. Convenient, accurate, remote tuning of a laser is achieved with the output wavelength displayed and/or retained in system memory.
Long term trends in Black Carbon Concentrations in the Northeastern United States

Abstract We report BC concentrations, ([BC]), measured using the thermal optical method, in monthly composites of daily particulate samples collected at rural Mayville, NY from 1984 to 2010. The monthly concentrations ranged from 10 to 900 ng m − 3 , and showed decreasing trend with a slope of − 5.5 ng m − 3 per year, and a 32% decrease over the 27-year period. The monthly [BC] varied weakly with season but generally peaked in late summer. An aethalometer was also used to measure [BC], in real time, every 5 min from May 2008 to December, 2010. Measurements were made at 370 and 880 nm wave-lengths. Although both channels are calibrated as BC, fresh wood combustion emissions include polycyclic aromatic hydrocarbons that enhance the 370 nm channel signal. We utilize this to estimate that the wood burning contributed 18% of the BC on an annual basis, but accounted for ~ 30% in winter and ~ 8% during summer. BC concentration from local and transported sources was calculated based on aethalometer BC and HYSPLIT 4 air trajectories. The highest [BC] were associated with air masses that passed through the Ohio River Valley as well as through the Mid-Atlantic States. However, when integrated over time 68% of the BC transported to the site arrived from OH, KY, IN, IL, MI, WI, and southern Ontario.
Effect of dose metrics and radiation risk models when optimizing CT x-ray tube voltage

We investigated the effect of different CT dose metrics, as well as the implications of various radiation risk models, on the optimization of x-ray tube voltage (kV) in CT. Soft tissue attenuation characteristics and noise levels, obtained from CT scans of a Rando phantom, were used to compute contrast-to-noise ratios (CNR) at x-ray tube voltages between 80 and 140 kV. Four CT dose metrics were evaluated: (a) CTDIair, (b) weighted CTDIw, (c) organ dose (Dorgan), and (d) effective dose (E). All doses were obtained using the ImPACT CT Dosimetry software package. Soft tissue CNR was adjusted by the modification of the mAs by assuming that CNR2 was proportional to mAs. Optimization criteria were: (a) maintaining a constant CNR at each kV and identifying the value that minimizes patient dose; and (b) maintaining a constant dose at each kV and identifying the value that maximizes CNR. We also investigated the implication for optimization strategies assuming that radiation risk is proportional to En, with n varying between 0 and 2. Optimizing with respect to phantom measurements (i.e., CTDIair and CTDIw) could generate results that differed quantitatively and qualitatively from those obtained using patient doses (i.e., Dorgan and E). For head CT scans, 140 kV offered the lowest patient doses as well as the highest CNR, whereas in abdominal scans 80 kV was optimal. Use of an optimal kV for CT imaging over current practice of using 120 kV might reduce patient doses by 10?15%, or improve CNR by 5?10%. Assuming that the risk was proportional to En made no difference to the optimal kV for positive values of n up to 2. We conclude that (a) CT optimization with respect to kV should generally be performed with respect to the patient effective dose, (b) neither CTDIair nor the body CTDIw are appropriate for use in CT optimization, (c) the range of current radiation risk models should not affect the optimal kV value in CT imaging.
Acute pulmonary embolism in pediatric patients awaiting heart transplantation.

Abstract Acute pulmonary embolism with infarction can delay urgently needed heart transplantation and increase the postoperative pulmonary complications. Few data are available concerning pulmonary embolization in the pediatric patient with end-stage congestive heart failure. Sixty-two consecutive pediatric patients awaiting heart transplantation were monitored for evidence of acute pulmonary embolism. Acute pulmonary infarction was documented by ventilation-perfusion scan, pulmonary angiography or pathologic examination in six patients. The prevalence differed by diagnosis; 5 of 36 patients with dilated cardiomyopathy and 1 of 20 patients with congenital heart disease developed acute pulmonary embolism with infarction. No significant difference in age at the time of transplantation evaluation, duration of congestive heart failure, presence of cardiac arrhythmias or degree of cardiac dysfunction was seen between patients with and without pulmonary embolism. Two-dimensional echocardiography failed to detect the presence of an intracardiac thrombus in four of the six patients. Two patients who developed acute pulmonary infarction are alive after successful heart transplantation. The remaining four patients died within 6 weeks of initiation of anticoagulant therapy before transplantation could safely be performed. In summary, pediatric patients with end-stage congestive heart failure are at risk for acute pulmonary embolism. No specific clinical factor identified those patients who developed acute pulmonary infarction. Anticoagulant therapy is strongly recommended in the pediatric patient with poor ventricular function awaiting heart transplantation.
Cage escape yields for photoinduced bimolecular electron transfer reactions of Re(I) complexes

Abstract The quantum efficiencies for formation of free radical ions (Φsep) following electron transfer quenching of the metal-to-ligand charge transfer (MLCT) excited state of a series of [(diimine)ReI(CO)3L]+ complexes by diaza[2.2.2]octane (DABCO) have been determined. The observed correlation between Φsep and the driving force for back electron transfer in the contact radical pair (ΔGBET) is consistent with a Marcus inverted region dependence of the rate of back electron transfer on ΔGBET. Comparison of the data for the present study with that for related systems suggests that: (i) the contact radical ion pair formed by electron transfer quenching has triplet spin multiplicity; (ii) the observed rate of charge recombination in the contact radical ion pair is controlled by the rate of triplet—singlet intersystem crossing.
Lymphocytic Infiltration in Pediatric Thyroid Carcinomas

Lymphocytic thyroiditis has been associated with an increase in the incidence of thyroid papillary carcinoma in some reports, mostly series of both adults and children. Relatively little is written about thyroiditis and follicular carcinomas. We have seen several cases of pediatric follicular thyroid carcinomas, that had an associated lymphocytic infiltrate, which led us to examine all primary malignant thyroid neoplasms in our surgical files from 1984 through 2000 to examine this relationship. We also investigated the nature of the lymphocytic infiltrate with routine immunohistochemistry. Ten patients (five male, five female, ages 4.5-21 years of age) had a thyroid carcinoma resection, six (three males and three females) with papillary carcinoma and four patients (two males and two females) with low-grade follicular carcinoma. Seven samples (one male had two cases with tumor) from patients who had a papillary carcinoma resection with tissue blocks available were identified (one patient had slides but no blocks), as were all four patients with a follicular carcinoma. The thyroid of all patients with a follicular carcinoma contained a lymphocytic infiltrate; only four of the seven papillary carcinoma samples had an associated lymphoid infiltrate. In all cases with a lymphoid infiltrate, the infiltrate was present in both lobes (both adjacent and separate from the tumor). B lymphocytes were present in the lymphoid infiltrate of three of four patients with follicular carcinomas and in 1 of 3 cases of papillary carcinomas. T cells were dispersed throughout all the tumors with lymphoid infiltrates. We conclude that pediatric follicular carcinomas have an associated lymphocytic infiltrate in the tumor and/or adjacent thyroid, more commonly than papillary carcinomas.
Generalized Multiple Economy Cost-of-Living Ordinary Annuities From an Interest Theory Perspective

The comprehensive development and application of progressive levels of generalization of the concept of a classic ordinary annuity from an interest theory perspective with either discrete or continuous compounding (first level) is the focus of this article. The second level incorporates the effect of inflation, or cost-of-living, on the annuity rent specified by a second interest rate. Next, we allow the principal to fund multiple investment economies, each with its own cost-of-living interest rate (third level). The fourth level recognizes the need for different payment spans and nonuniform economy-dependent annuity rents and its utility is illustrated with a multinational corporation capital investment example. At the fifth level, cost-of-living interest rates are allowed to vary over time. A retirement example illustrates application of the most generalized annuity formula derived. Finally, useful tables presented throughout the article summarize a total of 29 annuity formulas.
Alterations in brain glutathione homeostasis induced by the nerve gas soman

Public awareness of the dangers of chemical and biological warfare has been heightened in recent times. In particular, chemical nerve agents such as soman and its analogs have been developed and used in war as well as recent incidents, such as in Iraq and Japan. Soman, a rapid acting acetylcholinesterase inhibitor, produces a status epilepticus that leads to extensive neuropathology in vulnerable brain regions (eg, piriform cortex and hippocampus). This study was undertaken to determine whether oxidative mechanisms are involved in brain pathology during soman toxicity. Intracellular thiols such as glutathione (GSH) and protein sulfhydryls (PrSH) are among the most critical antioxidants used to combat oxidative stress. Here we report that during the seizure phase (1 h post soman exposure), PrSH levels in piriform cortex and hippocampus were decreased without changes in glutathione (GSH) levels. However, by 24 h post soman exposure (pathology phase), GSH levels were decreased by nearly 50% in the piriform cortex with a corresponding decrease in PrSH groups. The shift to a more oxidized thiol status indicates that oxygen free radicals likely participate in the neuropathology associated with soman-induced seizures.
Estuarine controls on fine-grained sediment storage in the Lower Mississippi and Atchafalaya Rivers

Observations of the lower Mississippi River channel in 1999–2003 with side-scan and subbottom seismic profilers, multibeam bathymetry, core radiotracers (7Be, 137Cs, 210Pb, and 234Th), and water-column profiles of fluid and suspended sediment properties are utilized to constrain the timing, location, and intensity of the seasonal storage of fine-grained sediments in the estuarine channel reach below Venice, Louisiana. Unlike earlier studies that suggested little or no estuarine sedimentation was taking place in the river, the present study demonstrates that the river channel above the Head of Passes seasonally stores as much as 10% of the annual suspended sediment discharge during periods of falling-to-low Mississippi water discharge associated with salt stratification in the channel thalweg. Mud deposits are up to 3.2 m thick with 7Be-derived sediment deposition rates of up to 8.9 mm/day. Water-column profiling and 234Th/7Be ratios suggest that (1) particles are transported and settled mainly as flocs; and (2) riverine flocs are settling through the strong salt-wedge halocline and are protected from re-erosion by the salt stratification. With onset of the spring freshet and the corresponding seaward retreat of the saltwater wedge, the entire volume of fine-grained material stored in the lower river (except in low freshet years) is remobilized and transported to the Gulf of Mexico in the turbid freshwater plume. This tidal hysteresis strongly influences the timing of sediment supply to the ocean: high turbidities in the shelf plume during rising water discharge spikes of 1- to 2-week duration are the product of local channel floor remobilization as well as increased supply from the drainage basin. Pulsed resupply of sediments and the pore-water products of early diagenesis potentially have major implications for issues such as continental margin carbon budgets and coastal eutrophication. Companion surveys conducted in the lowermost 12 km reach of the Atchafalaya distributary of the Mississippi show no evidence of saltwater wedge intrusion at low discharge or seasonal fine-grained sediment storage, likely due to the shallow (7 m) river-mouth sill that impedes the upstream movement of Gulf water.
Paramagnetic resonance absorption in two sulfates of copper

Resonance absorption measurements in CuS${\mathrm{O}}_{4}$ \ifmmode\cdot\else\textperiodcentered\fi{} 5${\mathrm{H}}_{2}$O and Cu${\mathrm{K}}_{2}$${(\mathrm{S}{\mathrm{O}}_{4})}_{2}$ \ifmmode\cdot\else\textperiodcentered\fi{} 6${\mathrm{H}}_{2}$O exhibit dissimilarities caused by different degrees of exchange coupling between paramagnetic ions. In the single salt, in which the ions are more closely spaced, exchange coupling causes the absorption lines to be much narrower than would be predicted on the basis of ordinary magnetic dipolar broadening, and causes the appearance of a single line in cases where two lines should otherwise be found. Neither of these effects is observed in the double salt.
The relationship between the Personal Ethical Threshold and workplace spirituality

This article explores the relationship between the Personal Ethical Threshold and workplace spirituality. We begin by reviewing our concept of the Personal Ethical Threshold, or PET, defined as an individual’s vulnerability to organizational pressures that can derail moral intentions. Next, we consider how individuals resolve their intrapersonal conflict when they violate their moral principles and we explain how to assess the PET. We tie the PET to workplace spirituality by focusing on flow as the expression of spirituality experienced by behaving with integrity, and then examining how organizations can encourage employees to act according to their values.
The effect of the fungi Ceratocystis minor (Hedgecock) Hunt, Ceratocystis minor (Hedgecock) Hunt var. barrasii Taylor, and SJB 122 on reproduction of the southern pine beetle, Dendroctonus frontalis Zimmermann (Coleoptera : Scolytidae)

The southern pine beetle, Dendroctonus frontalis Zimmermann, was studied in the laboratory to determine the influence of associated fungi on its reproduction. First-generation (P) surface-sterilized beetles associated with mycangial fungi (Ceratocystis minor [Hedgecock] Hunt var. barrasii Taylor or SJB 122) constructed more galleries and laid more eggs, at faster rates, than P beetles not associated with these mycangial fungi. No significant differences occurred among non-surface-sterilized P beetles associated with the phoretic blue staining fungus Ceratocystis minor (Hedgecock) Hunt and mycangial fungi or among progeny of P beetles (F1 generation) carrying mycangial fungi. P and F1 surface-sterilized beetles produced more eggs at a greater density than non-surface-sterilized beetles associated with blue stain, but gallery length and the rate of construction were not different. P and F1 surface-sterilized beetles laid more eggs and constructed galleries faster than surface-sterilized beetles that carried no mycangial fungi. The re-emergence rate of beetles was fastest for P beetles associated with C. minor and significantly slower for fungus-free P beetles, P beetles carrying only mycangial fungi, and F1 beetles, respectively. The F1 generation emerged fastest when associated with both mycangial fungi and slowest when associated with SJB 122, and C. minor var. barrasii or no fungus, respectively. This study employed a successful new rearing technique for isolating specific southern pine beetle/fungal associations.
An iteratively structured information processor

There exists a widely held belief that the full potential of LSI technology will be realized by arrays of logic circuits. A novel machine architecture is proposed that consists of a uniform array of identical cells with the property that the array executes a high-level programming language directly. Some of the more important features of such machines are their inherent abilities to sustain concurrent processes and to maintain efficient information storage. A detailed simulation of a language machine in its architectural style is presented.
Parallel direct SCF for large-scale calculations

Quantum chemistry has become an essential tool in many areas of chemical research; however, quantum chemistry is not yet playing a role in many exciting new chemical disciplines, such as medicinal chemistry and materials science, where the size of the chemical systems has been too large to study usingab initio chemical methods. The development of massively parallel supercomputers offers the potential to predict properties relevant to a variety of problems in these burgeoning new fields. The goal of this project is to develop a set of parallelized “production codes” for initially a relatively limited set of methods. As a key part of this project we are experimenting with the use of modern programming languages and methodologies to make these programs both portable and reusable. This paper describes the development of a massively parallel direct SCF program, MPSCF. For systems over a few hundred basic functions, MPSCF running on 256 nCUBE processors performs nearly as well as Gaussian 90 running on a single processor Cray Y-MP. On the next generation of parallel computers, such as the Intel Touchstone Delta, MPSCF should allow the SCF calculations on chemical systems too large for vector supercomputers.
Instantaneous response of elastic thin-walled structures with arbitrary open cross section to rapid heating

A generalized modeling and analysis approach of thermally-induced coupled vibrations of elastic thin-walled configurations with arbitrary open cross sections are presented in conjunction with a unified implicit transient methodology. Limited research appears in literature which takes into account the influence of rapid thermal heating effects on structures involving various forms of coupling. As a consequence, the dynamic response of such thin-walled structures of arbitrary open cross section due to rapid heating are described here. Effects involving triple, double, and no coupling between bending and torsional vibrations caused by sudden heating on these structures are examined. Numerical test cases are presented which describe the influence of sudden heating on elastic thin-walled structures of arbitrary open cross sections.