cssi/SciSciGPT-SciSciNet huggingface dataset:
Mixed convection in parallel channels with application to the liquid-metal reactor concept

In this paper mixed convection flow for parallel vertical channels connected at upper and lower plenums is studied. The one-dimensional conservation equations are formulated in dimensionless form using channel integral parameters. Based on this formulation, expressions are derived for stable flow and reversal of channel flow. The equations are then used to calculate the flow redistribution within a liquid-metal reactor core during natural circulation primary loop flow. A channel/plenum interaction phenomenon, which limits the applicability of using one-dimensional formulations, is modeled, and a correlation is formulated utilizing measured results to predict the onset of this behavior. Finally, the reversal of a heated channel from upflow to downflow, which cannot be predicted with a one-dimensional analysis, is described, and the channel/plenum interaction previously modeled is proposed as the mechanism that initiates this flow reversal.
Voluntary control of breathing affects center of pressure complexity during static standing in healthy older adults

Background Physiological/biomechanical systems display high degrees of complexity in their corresponding physiological and/or biomechanical outputs, indicative of normal healthy physiological functioning, though little attention has been paid to potential mechanisms which may affect complexity. Center of pressure (CoP) dynamics also display high degrees of complexity and may be affected via altered respiratory-motor interactions such as during voluntary control of breathing. Purpose The purpose of this study was to investigate the differences in the complexity of CoP dynamics during autonomous vs. voluntary control of breathing and between different voluntarily controlled breathing conditions. Methods Center of pressure recordings were taken from 18 older adults during static standing under three different breathing conditions: 1) neutral breathing, 2) abdominal breathing, and 3) thoracic breathing, the first constituting the autonomous breathing condition and the latter two constituting voluntarily controlled breathing conditions. CoP dynamics were quantified using sample entropy, standard deviation, 95% sway area, and average radial velocity. Repeated measure MANOVAs were used to assess the effect of breathing on CoP dynamics, with top-down application of ANOVAs and pairwise comparison as needed. Results Voluntary control of breathing during both conditions resulted in significantly higher CoP variability and lower sample entropy than during autonomous control of breathing in the mediolateral direction, indicating less complex dynamics and loss of system control. No significant differences between voluntary breathing conditions were observed. Conclusion Voluntary control of breathing significantly affected on CoP dynamics during static standing. The complexity of the postural control system may be affected via alterations in respiratory-motor interactions.
A randomized study to improve care for young women with breast cancer at community and academic medical oncology practices in the United States: The Young and Strong study

BACKGROUND The authors conducted a cluster randomized study to determine the effect of an exportable educational intervention for young women with breast cancer (YWI) on improving care. METHODS Sites were randomized 1:1 to the YWI or a contact time control physical activity intervention (PAI) stratified by academic or community site. Up to 15 women aged ≤45 years with newly diagnosed breast cancer were enrolled at each of 14 academic sites and 10 were enrolled at each of 40 community sites. The primary endpoint, attention to fertility, was ascertained by medical record review. Statistical inferences concerning the effect of the intervention used general estimating equations for clustered data. RESULTS A total of 467 patients across 54 sites were enrolled between July 2012 and December 2013. The median age of the patients at the time of diagnosis was 40 years (range, 22-45 years). Attention to fertility by 3 months was observed in 55% of patients in the YWI and 58% of patients in the PAI (P = .88). Rates were found to be strongly correlated with age (P < .0001), and were highest in patients aged <30 years. Attention to genetics was similar (80% in the YWI and 81% in the PAI), whereas attention to emotional health was higher in patients in the YWI (87% vs 76%; estimated odds ratio, 2.63 [95% confidence interval, 1.20-5.76; P = .016]). Patients rated both interventions as valuable in providing education (64% in the YWI and 63% in the PAI). CONCLUSIONS The current study failed to demonstrate differences in attention to fertility with an intervention to improve care for women with breast cancer, although attention to fertility was found to be higher than expected in both groups and emotional health was improved in the YWI group. Greater attention to young women with breast cancer in general may promote more comprehensive care for this population.
New insights into germ cell tumor genomics

Background Testicular germ cell tumors (GCTs) represent the most common malignancy in young men. While GCTs represent a model for curable solid tumors due to exquisite chemosensitivity, mortality for patients with GCT comprises the most life years lost for non-pediatric malignancies. Given limited options for patients with platinum-resistant disease, improved insight into GCT biology could identify novel therapeutic options for patients with platinum-resistant disease. Recent studies into molecular characteristics of both early stage and advanced germ cell tumors suggest a role for rationally targeted agents and potentially immunotherapy. Recent developments Recent GWAS meta-analyses have uncovered additional susceptibility loci for GCT and provide further evidence that GCT risk is polygenic. Chromosome arm level amplifications and reciprocal loss of heterozygosity have been described as significantly enriched in GCT compared to other cancer types. Contemporary analyses confirm ubiquitous gain of isochromosome 12 and mutations in addition to previously described GCT-associated genes such as KIT and KRAS. Alterations within the TP53-MDM2 signal transduction pathway appear to be enriched among patients with platinum-resistant disease. Potentially actionable targets, including alterations in TP53-MDM2, Wnt/β-catenin, PI3K, and MAPK signaling, are present in significant proportions of patients with platinum-resistant disease and may be exploited as therapeutic options. Pre-clinical and early clinical data also suggest a potential role for immunotherapy among patients with GCTs. Conclusion Molecular characterization of GCT patients may provide biologic rationale for novel treatment options in patients with platinum-resistant disease.
Formation of coarse sediment lags in ice-sediment mixtures: A geomorphic signature of sublimation on regolith surfaces

Abstract In many high-latitude locations on Mars, boulder sized clasts are present at the ground surface atop finer-grained sediments. These areas are concentrated in the latitude dependent mantle (LDM), an ice-rich surface unit that is globally distributed polewards of ∼30° latitude. Here, we test the hypothesis that sublimation of buried ice can drive grain size sorting in clastic deposits. We conducted pilot laboratory experiments to determine how buried and interstitial dry ice (CO2) sublimation modifies the grain size distribution in overlying and intermingled lithic sediments. We found that sublimation can sort grains into horizons with distinct grain size distributions by allowing fines to winnow into space freed by sublimation of underlying ice. On sloped surfaces, this mechanism enables lateral sorting by concentrating large grains on the surface and allowing them to slide or roll downslope. We infer that sublimation-driven sorting may affect the surface grain size distribution of solar system objects for which solid-vapor phase transitions dominate (e.g., modern Mars, comet 67P/Churyumov-Gerasimenko, asteroids, etc.).
Use of Topology Optimization to Design Shock and Vibration Test Fixtures

Engineering designers are responsible for designing parts, components, and systems that perform required functions in their intended field environment. To determine if their design will meet its requirements, the engineer must run a qualification test. For shock and vibration environments, the component or unit under test is connected to a shaker table or shock apparatus and is imparted with a load to simulate the mechanical stress from vibration. A difficulty in this approach is when the stresses in the unit under test cannot be generated by a fixed base boundary condition. A fixed base boundary condition is the approximate boundary condition when the unit under test is affixed to a stiff test fixture and shaker table. To aid in correcting for this error, a flexible fixture needs to be designed to account for the stresses that the unit under test will experience in the field. This paper will use topology optimization to design a test fixture that will minimize the difference between the mechanical impedance of the next level of assembly and the test fixture. The optimized fixture will be compared to the rigid fixture with respect to the test’s ability to produce the field stresses.
Uncovering the dynamic fracture behavior of PMMA with peridynamics: The importance of softening at the crack tip

Abstract Recent experimental investigations of dynamic crack propagation in PMMA induced by impact show single cracks running stably at around 300–400 m/s. Existing numerical models for simulating dynamic fracture in PMMA consistently produce crack propagation speeds significantly higher than those measured experimentally. Here we uncover the reason for this puzzle by showing that localized material softening in the fracture process zone (caused by heating due to high strain rates in front of the crack tip), leads to crack propagation speeds that match the observed ones. We introduce a new constitutive model in our peridynamic formulation for PMMA to account for a softer material in the crack tip region. With the new model, the computed crack speed and crack length evolution match very closely those found experimentally.
EDF-Based Mixed-Criticality Scheduling with Graceful Degradation by Bounded Lateness

Mixed-criticality (MC) scheduling has been proposed for embedded real-time systems to alleviate the dilemma between runtime resource utilization and worst-case temporal guarantees for critical functions. The approach of dropping all low-criticality tasks upon a mode switch has been criticized for potentially over-degraded performance. In this paper, we focus on the graceful degradation for MC scheduling by providing bounded lateness for certain low-critical tasks. We define MCQOS-schedulability that massages the required bounded lateness into the definition of conventional MC-schedulability. A virtual deadline based scheduler (EDF-VDS) is proposed with utilization-based MCQOS-schedulability test and and closed-form lateness bounds.
Effect of MoS2 film on memristor characteristics of ZnO film

Memory resistive devices using a ZnO dielectric layer are promising due to the transparent nature, lower operating voltage, synthesis compatible with semiconductor processing, and ability to control using magnetic fields. In the present work, niobium incorporated MoS2 films in combination with ZnO are used to form diode-resistor devices with memory. The two device structures p-Si-SiO2/Pt/MoS2(Nb)/ZnO/Ag and p-Si-SiO2/Pt/ZnO/Ag are grown using laser physical vapor deposition. The resistive characteristics are investigated as a function of temperature for comparison. The unipolar I-V characteristics of Pt/ZnO/Ag device films were found to be nonreproducible, and the temperature dependence was irregular for negative polarity. The unipolar I-V characteristics of Pt/MoS2(Nb)/ZnO/Ag device films were found to be reproducible. The temperature dependence of the I-V characteristics was regular for both polarities. The presence of a MoS2 film is found to improve and distinguish the effect of the polarity of the applied field on the unipolar device characteristics by the formation of a p-n device configuration. The conductance in the transition from a low resistance state to a high resistance state was found to follow the Schottky emission with the apparent barrier height being influenced by the p-n junction.
The Role of Academia in Data Science Education

As the demand for data scientists continues to grow, universities are trying to figure out how to best contribute to the training of a workforce. However, there does not appear to be a consensus on the fundamental principles, expertise, skills, or knowledge-base needed to define an academic discipline. We argue that data science is not a discipline but rather an umbrella term used to describe a complex process involving not one data scientist possessing all the necessary expertise, but a team of data scientists with nonoverlapping complementary skills. We provide some recommendations for how to take this into account when designing data science academic programs.Keywords: applied statistics, data science, data science curriculum, data wrangling, machine learning, software engineering
Mechanistic foam flow model with variable flowing foam fraction and its implementation using automatic differentiation

Abstract Foam injection is an effective method for modifying gas mobility in subsurface flow applications making it ideal for environmental remediation applications. Remediation of contaminated soils/aquifers of nonaqueous phase liquids using foamed surfactant solutions is a viable option but a predictive foam model is needed that is flexible to the addition of more accurate physical descriptions. Such a model is essential to ensure successful operations in soil remediation applications. The objective of this paper is to develop a full-physics, mechanistic transient foam flow model and integrate it into the multiphysics, modular AD-GPRS framework (Automatic Differentiation–General Purpose Research Simulator). We chose AD-GPRS because it allows rapid prototyping and addition of complex physics and modeling strategies. We develop the model ground-up from pore-scale observations and implement a new flowing foam fraction constitutive relation that depends on the local pressure gradient, local permeability, and flowing bubble density. Our model predicts the two flow regimes commonly observed in steady-state pressure gradient measurements: the low-quality regime and the high-quality regime. Additionally, the model is used to match transient experimental results of homogeneous and slightly heterogeneous cores with a wide range of permeability values. The implementation of this model within AD-GPRS allows testing of ideas and modeling strategies as well as inclusion of more complex physics or foam generation kinetics.
The Effects of Lower vs Higher Cell Number of Platelet-Rich Plasma (PRP) on Hair Density and Diameter in Androgenetic Alopecia (AGA): A Randomized, Double-Blinded, Placebo, Parallel-Group Half-Scalp IRB-Approved Study.

BACKGROUND Androgenetic alopecia (AGA) is a common disorder in both males and females and may be improved by platelet-rich plasma (PRP) treatment. OBJECTIVES The aim of this study was to compare safety, efficacy, and satisfaction following treatment with a lower or higher number of platelets over 6 months. METHODS This was a prospective randomized, double-blinded, placebo, parallel-group, half-scalp IRB-approved study involving 8 subjects with moderate AGA. Participants received intradermal PRP injections (baseline and Month 3), according to 2 treatment protocols (high vs low platelet numbers) to the frontal and crown portions of the hemiscalp and normal saline to control sites. Phototrichoscans were recorded at baseline and at 6 months, and global photography and subject and investigator satisfaction questionnaires were obtained at baseline, 3, and 6 months. RESULTS At the end of 6-month evaluation period, both groups demonstrated absolute increases in total hair density, follicle diameter, and terminal hair density, as well as absolute and percentage changes at the frontal and crown targeted sites compared with baseline. These improvements tended to occur more often in areas treated with higher platelet numbers than with lower numbers. Vellus hair densities did not exhibit any significant changes with either PRP dosages. The investigator and 6 of the subjects were "satisfied" with the results at 3 months and no adverse reactions were associated with the treatments. CONCLUSIONS Intradermal injections with 2 therapeutic quantities of platelets were equally safe and efficacious for treating men and women with AGA. Higher numbers of platelets may have a greater effect than lower numbers of platelets in regard to hair density, follicle diameter, and terminal hair density but exhibited minimal effects on vellus hair densities at the 6-month evaluation point. Further studies are required to determine whether any significant advantages occur when delivering either lower or higher numbers of platelets in AGA treatments as long as therapeutic levels are administered. LEVEL OF EVIDENCE: 2
The Revitalization of Ghost Town

Detroit has been nicknamed ghost town because of the urban blight caused by deindustrialization, depopulation, and abandoned buildings. There has been progress in blight removal from Detroit through Detroit Land Bank Authority, Detroit Home Mortgage Program, Nuisance Abatement Program Neighborhood Revitalization, Vacant Properties Defensive Architecture, Poverty Property Tax Exemptions, and most recent federal funding.
Differences in Parents’ Attitudes Toward Spanking Across Socioeconomic Status and Region, 1986–2016

This paper explores whether and how parents’ attitudes toward the spanking of children have changed over the last 30 years, a period when parents’ use of corporal punishment declined precipitously in the U.S. We compare these trends across parents’ socioeconomic status (SES) and region of the country to identify whether shifts in attitudes toward these practices parallel documented shifts in their use by SES and region. We draw data from the General Social Surveys (GSS) from 1986 through 2016, which asked respondents how much they agree children sometimes need “a good, hard spanking.” We compare responses among parents at the 80th (high-SES) and 20th (low-SES) percentiles of the income and education distributions, and between parents in southern versus non-southern states, controlling for child and parent age and parent gender. In non-southern regions, parents’ support for corporal punishment declined over time, especially among high-SES parents, whereas in the South parents’ support for corporal punishment remained stably high over time across the socioeconomic distribution. These findings imply a distinct cultural perspective on corporal punishment in the South, one that may help explain the disproportionate maintenance of the practice in schools and provide a potent target for policy and program interventions to reduce its use.
Rough asymptotics for tandem non-homogeneous M/G/\infty queues via Poissonized empirical processes

We obtain a large deviations principle and moderate deviations principle for the joint distribution of the queue length processes and departure process for tandem M / G / \infty queues. The results are obtained by applying a result providing necessary and sufficient conditions on a class of functions for a large deviations principle and moderate deviations principle to hold for a Poissonized empirical process over the class of functions. As an application, we examine how large queue lengths and numbers of departures are built up.
Depoliticization and the Structure of Engineering Education

The need for engineering students to develop nuanced understandings of the cultural, social, and political contexts of socio-technical systems has never been more obvious to engineering leaders and decision-makers. Yet, engineers often have obtuse definitions of their responsibilities to the public and seem to engage with the socio-cultural contexts and consequences of their work only in times controversy. A central underlying factor in this disengagement from considerations of social justice and equality is the ideology of depoliticization, the belief that engineering is a purely “technical” space in which engineers design technological objects and systems stripped of political and cultural concerns. In this chapter, we ask, what role does the culture and structure of engineering education play in promoting depoliticization? After elaborating the ideology of depoliticization, we argue that the culture of engineering pedagogy and the traditional curricular structure of engineering education (both its accreditation process and its intra-program curricula) help support and promote an ideology of depoliticization in engineering and train students to adopt this ideology within their own understandings of their professional roles and responsibilities. We end by discussing the consequences of having depoliticization embedded in the culture and structure of engineering education, and suggest possible policy solutions to re-politicize engineering education.
Exploration of Firefighter Bunker Gear Part 2: Assessing the Needs of the Female Firefighter

Female firefighters are a minority in their workplace yet also need the same protective equipment as their male counterparts. This research focused on the problems with their bunker gear that female firefighters themselves have identified. Focus groups were held in around the country and the comments made by female firefighters were analyzed. Data were organized by identifying the most common problems areas. Five gear factors (i.e. garment design features, sizing, fit, mobility, and fabrication) are discussed within two main constructs; function and comfort. Suggestions on improving bunker gear for female firefighters include altering the fit and sizing, as well as changing the location of pockets and enhancing the functionality of the suspenders.
Bacteriuria in Pregnancy

The urinary tract undergoes profound physiologic and anatomic changes during pregnancy that facilitate the development of symptomatic urinary tract infections in women with bacteriuria. While the adverse effects of asymptomatic bacteriuria on maternal and fetal health continue to be debated, it is clear that asymptomatic bacteriuria is the major risk factor for developing symptomatic urinary tract infection and that symptomatic infections are associated with significant maternal and fetal risks. Because the majority of symptomatic urinary tract infections develop in women with bacteriuria earlier in pregnancy, treatment of bacteriuria is undertaken to prevent symptomatic infections. All women should be screened at the first antenatal visit, which is reliably and inexpensively done with a dipstick culture. Short-course therapy is as effective as prolonged therapy and should be followed with a repeat culture to document clearing of the bacteriuria. Failure to eliminate bacteriuria with repeated therapy or recurrence with the same organism is indicative of renal parenchymal infection or a structural abnormality. All women with persistent bacteriuria or recurrent infection should have follow-up cultures and a complete urologic evaluation after delivery.
A reduced grid model for shallow flows on the sphere

The authors describe a numerical model for simulating shallow water flows on a rotating sphere. The model is augmented by a reduced grid capability that increases the allowable time step based on stability requirements, and leads to significant improvements in computational efficiency. The model is based on finite difference techniques, and in particular on the nonoscillatory forward-in-time advection scheme MPDATA. They have implemented the model on the massively parallel CM-5, and have used it to simulate shallow water flows representative of global atmospheric motions. Here they present simulations of two flows, the Rossby-Haurwitz wave of period four, a nearly steady pattern with a complex balance of large and small scale motions, and also a zonal flow perturbed by an obstacle. They compare the accuracy and efficiency of using the reduced grid option with that of the original model. The authors also present simulations at several levels of resolution to show how the efficiency of the model scales with problem size.
Modeling the Determinants of Farmland Values in the United States

Farmland has long represented a significant component of both farm sector and farm household assets. This chapter provides a comprehensive overview of significant developments in modeling farmland values, with attention to methodological challenges and recent modeling innovations. After outlining the capitalization model that provides the theoretical underpinnings for most farmland value studies, the merits and efficacy of dynamic models using aggregate data, as well as increasingly popular cross-sectional hedonic models that use spatially disaggregate data are presented. Estimation issues in hedonic models are reviewed, with a focus on those deserving special consideration in the context of farmland values such as spatial dependence and heterogeneity and sample selection bias. Promising future research directions include greater use of nonparametric approaches, quasi-experimental designs, panel data analyses, and structural econometric models, which take advantage of spatially explicit farmland values data but avoid the restrictive assumptions of standard spatial lag and spatial error models.
Wind-blown dust as a source of nutrients for aquatic plants

Abstract The importance of natural and man-made dust accumulated on plant leaves, to the plant itself and to the surrounding vegetation, has received little attention, although several workers have shown that this may be a form of pollution causing damage to plant growth. This paper reports the results of an experiment to measure the response of Lemna perpusilla to dust washed from the stems of Scirpus californicus which grows with the duckweed. Duckweed growth was stimulated by the washings and it was also found that growth could be stimulated by dust that had accumulated on a concrete wall near the lake. It is evident that dust from both sources can produce an immediate growth response by duckweed and so must contain soluble nutrients. There is some evidence that salts leached from the Scirpus stems may have been partially responsible for the increase in growth, and the utilisation of nutrients from this source by aquatic plants represents a previously unsuspected pathway in the nutrient cycle of a lake.
Characterization of a water-equivalent fiber-optic coupled dosimeter for use in diagnostic radiology.

This work reports on the characterization of a new fiber-optic coupled (FOC) dosimeter for use in the diagnostic radiology energy range. The FOC dosimeter was constructed by coupling a small cylindrical plastic scintillator, 500 {mu}m in diameter and 2 mm in length, to a 2 m long optical fiber, which acts as a light guide to transmit scintillation photons from the sensitive element to a photomultiplier tube (PMT). A serial port interface on the PMT permits real-time monitoring of light output from the dosimeter via a custom computer program. The FOC dosimeter offered excellent sensitivity and reproducibility, allowing doses as low as 0.16 mGy to be measured with a coefficient of variation of only 3.64%. Dose linearity was also excellent with a correlation coefficient of 1.000 over exposures ranging from 0.16 to 57.29 mGy. The FOC dosimeter exhibited little angular dependence from axial irradiation, varying by less than 5% over an entire revolution. A positive energy dependence was observed and measurements performed within a scatter medium yielded a 10% variation in sensitivity as beam quality changed due to hardening and scatter across a 16 cm depth range. The current dosimetry system features an array of five PMTs to allow multiplemore » FOC dosimeters to be monitored simultaneously. Overall, the system allows for rapid and accurate dose measurements relevant to a range of diagnostic imaging applications.« less
Nitric oxide dependent and independent effects of in vitro incubation or endotoxin on vascular reactivity in rat aorta

We sought to delineate contributions of nitric oxide (NO) and other mechanisms to impairment of contraction and endothelium-dependent relaxation following prolonged in vitro incubation, endotoxin and interleukin-1 exposure in isolated rat aorta. Responses from freshly-dissected (control) rings +/-endothelium were compared with those from rings incubated in sterile, antibiotic containing medium +/- E. Coli endotoxin (LPS, 100 microg/ml) +/- interleukin-1 (IL-1, 40 ng/ml) at 37 degrees C for 20-24 h. In some experiments, medium included dexamethasone (DEX, 1 microg/ml), cycloheximide (10 microg/ml), or N(G)-nitro-L-arginine (NNLA, 10(-4)M). After incubation, medium nitrite was measured. Incubation alone, without addition of inflammatory mediators, impaired contraction in an agonist-specific manner, by both NO-dependent and NO-independent mechanisms. Either LPS or IL-1 diminished contraction further, in a similarly heterogeneous manner. For example, contractions were changed in LPS-incubated endothelium-intact rings (vs. fresh controls) by -85%, +115%, -15%, -96%, and -37% for phenylephrine (PE), serotonin, prostaglandin F2alpha, angiotensin II, and U46619, respectively. NO synthase inhibition with NNLA either following, or during LPS incubation only partially normalized subsequent PE contractions, an effect which was smaller than that of DEX. Nitrite accumulation was inversely proportional to PE response, even though NO was not the sole mediator of LPS-impaired contraction. LPS and IL-1 nearly abolished ACh-induced relaxation, which was only mildly impaired by incubation alone. We conclude that prolonged incubation impaired vasoconstriction via both NO synthase induction and NO-independent mechanisms. LPS or IL-1 incubation impaired vasoconstriction further, primarily by NO-independent mechanisms. Moreover, vasoconstrictor responses following LPS varied with the agonist's ability to modulate endothelial NO release. These results are in accord with the failure of NO synthase inhibition to fully restore systemic vascular resistance indices in experimental endotoxemia or in hyperdynamic septic patients.
Optimized Low-Thrust Orbit Transfer for Space Tugs

Introduction Recent advances in low-cost, commercial launch systems predict rapid insertion of relatively large payloads into Low Earth Orbit (LEO). At the same time, extensive work performed on radiation hardening of solar cells—specifically GaAs, InP and InGaP/GaAs cells—has permitted repeated transfers through the Van Allen belt with minimal loss of conversion efficiency. 1 The combined impact of these two technological advances suggests that a market for an in-space transportation system capable of ferrying payloads from LEO to GEO and beyond is not only possible, but desirable. The space tug configuration demonstrates a viable candidate for an Earth-Moon cargo vehicle system satisfying NASA’s Vision for Space Exploration. Establishment of permanent outposts on the Moon will require the transfer of large quantities of cargo to the Moon’s surface at low cost. A high power, reusable, solar electric propulsion system optimized for both transfer mass and transfer time is capable of delivering high-tonnage cargo per year to the surface of the Moon. The cost saving from both the use of smaller launch vehicles and the reuse of the power and propulsion subsystems makes such a mission system an attractive choice for the Lunar Exploration Program. In this note, the authors apply an optimization technique previously developed by Burton and Wassgren 2 to a reusable electrically-propelled Earth-Moon “space tug” transfer vehicle proposed by Spores et al. 3 Both transfer mass and mission time are optimized, and the results show that significant reductions in the round trip transfer time can be achieved. In addition, either the initial launch mass can be significantly reduced, while keeping the yearly delivered payload constant, or the yearly delivered cargo can be significantly increased by appropriately increasing the available power.
Reflection, Racial Competence, and Critical Pedagogy: How Do We Prepare Pre-Service Teachers To Pose Tough Questions?.

In this article, the author argues that pre-service teachers may need to reflect about race and pursue racial competence as they are prepared to teach in multiracial schools. The question is how do teacher educators prepare pre-service teachers to pose tough questions about issues of race? Several matters are considered in the discussion, such as teacher reflection, race reflection, and some complexities of race in the teaching and learning process. The author concludes the article with an extensive discussion of critical pedagogy. In particular, the author advances two possible teaching methods (critically engaged dialogue, and race reflective journaling) that teacher educators may find useful as they attempt to facilitate reflections on race and assist pre-service teachers in pursuing racial competence through posing tough questions. In the final section, the author shares a chart that he developed and suggests that the chart be used in critically engaged dialogue and race reflective journaling as pre-s...
Attentional Modulation in the Detection of Irrelevant Deviance: A Simultaneous ERP/fMRI Study

Little is known about the neural mechanisms that control attentional modulation of deviance detection in the auditory modality. In this study, we manipulated the difficulty of a primary task to test the relation between task difficulty and the detection of infrequent, task-irrelevant deviant (D) tones (1300 Hz) presented among repetitive standard (S) tones (1000 Hz). Simultaneous functional magnetic resonance imaging (fMRI)/event-related potentials (ERPs) were recorded from 21 subjects performing a two-alternative forced-choice duration discrimination task (short and long tones of equal probability). The duration of the short tone was always 50 msec. The duration of the long tone was 100 msec in the easy task and 60 msec in the difficult task. As expected, response accuracy decreased and response time (RT) increased in the difficult compared with the easy task. Performance was also poorer for D than for S tones, indicating distraction by task-irrelevant frequency information on trials involving D tones. In the difficult task, an amplitude increase was observed in the difference waves for N1 and P3a, ERP components associated with increased attention to deviant sounds. The mismatch negativity (MMN) response, associated with passive deviant detection, was larger in the easy task, demonstrating the susceptibility of this component to attentional manipulations. The fMRI contrast D > S in the difficult task revealed activation on the right superior temporal gyrus (STG) and extending ventrally into the superior temporal sulcus, suggesting this region's involvement in involuntary attention shifting toward unattended, infrequent sounds. Conversely, passive deviance detection, as reflected by the MMN, was associated with more dorsal activation on the STG. These results are consistent with the view that the dorsal STG region is responsive to mismatches between the memory trace of the standard and the incoming deviant sound, whereas the ventral STG region is activated by involuntary shifts of attention to task-irrelevant auditory features.
Extracellular matrix in bone marrow cell cultures. Synthesis of a 45k non-collagenous protein and a 17k protein sensitive to bacterial collagenase.

Abstract Proteins produced by bone marrow constituents are of importance to hematopoiesis and osteogenesis. To elaborate the role of bone marrow in these functions the proteins synthesized by rat bone marrow cells in culture were evaluated. In addition to types I and III procollagen and fibronectin, two novel proteins were produced by the adherent stromal cells, a 45 kDa protein, and a 17 kDa protein which is sensitive to bacterial collagenase. The 45k protein is sensitive to pepsin digestion, contains no disulfide bonds, has no precursors or breakdown products on pulse-chase analysis and is maximally synthesized in young cultures (5days old) with decreased synthesis as time in culture increases. The 17k protein is sensitive to digestion by bacterial collagenase and pepsin, appears without precursors or breakdown products on pulse-chase analysis and is maximally synthesized in 5 day old cultures. Synthesis decreases with longer times in culture. The 17k protein is not a degradation product of a collagen precursor and appears to be a novel protein in bone marrow cell cultures.
Comparison of Hybrid Ensemble/4DVar and 4DVar within the NAVDAS-AR Data Assimilation Framework

AbstractThe effect on weather forecast performance of incorporating ensemble covariances into the initial covariance model of the four-dimensional variational data assimilation (4D-Var) Naval Research Laboratory Atmospheric Variational Data Assimilation System-Accelerated Representer (NAVDAS-AR) is investigated. This NAVDAS-AR-hybrid scheme linearly combines the static NAVDAS-AR initial background error covariance with a covariance derived from an 80-member flow-dependent ensemble. The ensemble members are generated using the ensemble transform technique with a (three-dimensional variational data assimilation) 3D-Var-based estimate of analysis error variance. The ensemble covariances are localized using an efficient algorithm enabled via a separable formulation of the localization matrix. The authors describe the development and testing of this scheme, which allows for assimilation experiments using differing linear combinations of the static and flow-dependent background error covariances. The tests are ...
Risk Prediction for Progression of Macular Degeneration: 10 Common and Rare Genetic Variants, Demographic, Environmental, and Macular Covariates.

The era of personalized medicine and targeted therapies is emerging in many areas of medicine. In ophthalmology, the disease age-related macular degeneration (AMD) stands alone in having several environmental and genetic risk factors with confirmed, combined high impact on its development and progression. The combination of demographic, behavioral, and genetic factors can achieve a high predictive value for progression to advanced stages of disease approaching 90%, unlike any other disease.1–,5 We developed genetic risk algorithms in 2006,6 subsequently adding nongenetic markers7 and more common genetic variants,2–,4,8 then recently validated these risk models in an independent study cohort.5 More genetic loci in a 9 gene model, including the strongly related rare variant in the gene CFH (R1210C),9 and common loci RAD51B and COL8A1,10,11 enhanced predictability for transition from early and intermediate stages to advanced disease.12 Knowledge about the genetic underpinnings of AMD continues to expand. New, rare genetic variants have been discovered in case-control association studies in the genes C313–,15 and C9,13 as well as a burden of several rare variants in CFI.13 While these variants are uncommon, they have a stronger impact on the development of the disease individually compared with the low to moderate impact of the 20 or more common variants associated with AMD. Given that previous analyses were based on cross-sectional analyses of prevalent cases, and that progression of disease over time can have different underlying predictors, we conducted longitudinal analyses to determine the impact of these new rare variants on transition to the late stages of AMD resulting in visual loss over time. We also assessed the independent association of these new variants on progression, controlling for other genetic and nongenetic predictors. Building upon our previous algorithms, we developed and assessed a new risk prediction model for progression of AMD (rPPMD) and evaluated the degree to which AMD progression could be attributed to its various components: environmental, ocular, and genetic. In order to lay the groundwork to disseminate these predictive models for clinical use, we developed a software framework and analytics components in the form of an online browser-based calculator (seddonamdriskscore.org, available in the public domain) to demonstrate its use with various subject risk profiles. The rPPMD software components are also designed to be adapted as a stand-alone application for a personal computer or mobile devices such as smartphones and tablets.
Modeling realism in wireless simulations

This paper presents a ray-tracing technique to model the multi-path fading effect in indoor spaces. Random set P of points on all 2D planes inside a given hypothetical indoor space are chosen. Each p i ∈ P is considered to be a point from which the transmitted signal reflects just before reaching the receiver. A vector sum of the signals that arrives at the receiver from each point p i provides the resultant signal at the receiver. The received signal strength (RSS) is then computed as the signal envelope of this signal. This technique provides RSS statistics that are similar to those developed after extensive measurements in multi-path environments. In addition, this technique captures the spatial correlation of signal impairment. For example, path loss computed with this technique shows that co-moving receivers experience correlated signal fades while those moving in different spaces see un-correlated fading. The goal of this work is to implement this, low cost, ray-tracing approach in network simulators for experiments that require a spatial contexts such as path diversity in a mmWave system or for leader selection for data forwarding in a dense Internet of Things deployment and proof-of-concept evaluation of inference algorithms for indoor localization. This technique does not compete with or replace other, more accurate and deterministic ray-tracing techniques that use either brute force or geometric optics combined to obtain site-specific signal-to-space mapping.
Climatic and geographic temporal patterns of pain in the Multicenter Study of Hydroxyurea

No multi-site comparisons have tested whether seasonally cold temperature or climate exacerbate pain intensity in sickle cell disease (SCD). We examined seasonal SCD pain intensity and frequency patterns and compared them with concurrent climate conditions (temperature and barometric pressure) and geography of patient residence in the Multicenter Study of Hydroxyurea (MSH). We conducted a time series analysis of the monthly average daily pain intensity (0–9 scale) and pain frequency of the 299 MSH patients from December 1991 to December 1994. We used both an unobserved component model (UCM) and a nonparametric local regression (LOESS) to probe for a cycle and/or trend associated with the time series. We also examined base mixed regression models of season, monthly average temperature and barometric pressure, and geographic region as stand-alone predictors of pain intensity and frequency. Expanded models included additional predictor variables. UCM and LOESS analyses showed a cyclic pattern of pain intensity and frequency with peaks in late Fall/early Winter and troughs in Spring. Base regression models showed colder seasons were significantly associated with greater pain intensity (p = .0035) but not frequency (p = .07); higher monthly temperatures were significantly associated with both lower pain intensity and pain frequency, but higher monthly barometric pressures were significantly associated with greater pain intensity and frequency (all p’s < .0001); and northern sites had nonsignificantly higher pain intensity (p = .40) and frequency (p = .07) than southern sites. This pattern of results did not change in expanded models including other predictors. Our results suggest that seasonably colder temperatures exacerbate sickle cell-related pain, but low barometric pressure does not, and geographic region of residence is not significantly related to pain in this sample.
SERUM SALICYLATE CONCENTRATIONS IN REYE'S DISEASE: A Study of 130 Biopsy-proven Cases

Abstract Serum salicylate concentration was measured at admission in 130 children with liver-biopsy-confirmed Reye's disease. Mean serum salicylate was 12·3 mg/dl and mean salicylate concentrations by neurological grade (Lovejoy) were: stage I, 12, stage II, 13, stage III, 11, stage IV, 13, and stage V, 13 mg/dl. However, mean serum salicylate (15 mg/dl) at admission in 21 patients who died or had serious neurological deficits was significantly higher than that in 103 patients who survived without neurological sequelae (10 mg/dl). Serum salicylate in a group of 27 age-matched, community-matched control children collected consecutively over the period 1978-80 was less than 2 mg/dl, and children with varicella or influenza had salicylate concentrations indistinguishable from apparently well classmates or siblings. It is impossible to determine from this data whether salicylates are involved in the aetiology of or in determining the outcome of Reye's disease. Increased concentrations of salicylates at admission could be the result of excessive dosage because of a greater severity of the prodromal illness, or to diminished excretion because of impaired hepatic metabolism. It seems likely that serum salicylate concentrations entered the toxic range in many patients with Reye's disease before they presented for treatment. Most had been vomiting and had had diminished oral intake for 33-55 h before hospital admission. Since the average number of hours from the beginning of vomiting to admission was no different in non-comatose and comatose cases, the time at which salicylate concentration was measured in relation to the last dose was probably similar in the two groups and therefore does not account for the higher levels in children with poor outcome. Salicylates are mitochondrial toxins and mitochondria are known to be significantly injured in Reye's disease; therefore, it seems wise to avoid the use of aspirin in children during outbreaks of Reyes's disease.
Effects of day length and endogenous control on the annual reproductive cycle of the antelope ground squirrel,Ammospermophilus leucurus

1. Male antelope ground squirrels were removed from the field in fall, winter, spring, and summer and separate groups exposed for 50 days each to photoperiods of 16 h (LD 16∶8) and 8 h (LD 8∶16) and ambient temperature of 23 ‡C. Control samples from the field were obtained at the beginning and end of each of these experiments. A single experiment was conducted with females in winter. 2. At no time of year was there a significant difference (P>0.05) in the mass or condition of reproductive tissues of animals exposed to LD 16∶8 and those exposed to LD 8∶16. The changes in both long-day and short-day groups during each experiment paralleled the natural seasonal reproductive cycle, with a peak in late winter and early spring. 3. In association with an annual cycle of body mass,A. leucurus showed significant seasonal differences in the tendency to increase body mass and gonadal fat when held in captivity; however these responses were also unaffected by differences in experimental photoperiod. 4. Because the 50-day manipulations of photoperiod did not affect testicular activity at any season, we conclude that the annual gonadal cycle ofA. leucurus is under endogenous control. Factors that may have been involved in the evolutionary history of this adaptation are discussed.