cssi/SciSciGPT-SciSciNet huggingface dataset:
Semiconductor Nanowire Lasers

Semiconductor nanowires can function as both gain medium and optical cavity, and thus represent a unique class of miniaturized laser sources for the assembly of nanoscale photonic systems. In this talk we will review the rational design and synthesis of nanowires and nanowire heterostructures as laser sources, describe how their structure design interplays with optical properties, and discuss exciting device applications. Group III-nitride nanowire structures will be used as a model system to illustrate our approach towards nanowire lasers. First, the general synthetic strategy for rational growth of semiconductor nanowires and the underlying physical mechanism of lasing in these materials will be reviewed. Second, structural characterization and photoluminescence studies of homogeneous GaN nanowires will be discussed. These studies will illuminate how basic structural characteristics affect threshold for ultraviolet room-temperature lasing in these homogeneous structures. Third, multicolor nanowire lasers based on InGaN multi-quantum well (MQW) radial nanowire heterostructures will be described. Cross-sectional transmission electron microscopy studies allow direct visualization of well-defined internal interfaces and demonstrate our ability to control quantum well growth down to atomic level. These functional nanowire structures were optically pumped individually to lasing from 380 to 494 nm at room temperature, depending on the alloy composition of MQWs. Key factors contributing to the lasing threshold were evaluated by three-dimensional finite-difference time-domain calculations. Last, current injection schemes for electrically-driven nanowire light-emitting diodes/lasers with the emphasis on n-GaN/InGaN MQW/p-AlGaN/p-GaN radial nanowire heterostructures will be discussed.
The Continuing Search for Relevance in Agricultural Economics

Agricultural economists have published thought-provoking papers on the problems of the land grant system (LGS), in general, as well as discussions of how agricultural economists can adjust resident teaching, research, and outreach programs to provide more relevant educational materials for society. Some of the recommendations presented must be implemented by individual universities, government agencies, institutes, research groups, or businesses. Others can be implemented by the American Agricultural Economics Association (AAEA). The association has responded to some of these ideas, adjusting the composition of the program at the annual meeting and providing some additional services to members. Given the demand
Should the removal of water be taken into account in the analysis of kinetic data of polyesterification reactions

In most polyesterification reactions, the concentrations of acid, alcohol and catalyst (if present) are expressed in moles per unit mass of the charge, denoted as moles/kg. In this paper, a general kinetic equation that takes water removal into account has been derived. It has been shown that (i) when the progress of reaction is followed by titration of acid, the removal of water affects the concentrations of alcohol and catalyst; and (ii) the ratio of the rate constants that do and do not account for water removal is smaller than unity, and it varies with the degree of reaction. On the other hand, it has been found that the rate constant obtained using moles/kg as the unit of concentration is not a real constant but a function of the charge density. Treating it as a constant may lead to appreciable error or misinterpretation.
Reentry: Insights From Theoretical Simulations in a Fixed Pathway

Reentrant Activity in Cardiac Tissue. This review article summarizes theoretical insights into the principles and mechanisms associated with reentrant activity in cardiac tissue. A mathematical ring model is used in computer simulations to investigate, at the cellular level, mechanistic aspects of initiation, perpetuation, and termination of reentry. Taking advantage of the ability to compute membrane processes in this model, we relate dynamic properties of the reentrant action potential (e.g., beat-to-beat alternans) to the underlying kinetics of membrane ionic channels. Effects on reentry of inhomogeneities in refractoriness, excitability, cellular coupling at gap junctions, and fiber cross-section are also studied.
Intrinsic Narrow Absorption Lines in Keck HIRES Spectra of a Sample of Six Quasars

In the course of a large survey of intervening Mg II absorbers in the spectra of quasars, the C IV emission lines of six of the target objects (three radio-loud and three radio-quiet) were observed serendipitously. In four of these six quasars, we detected "associated" narrow absorption lines with velocities within 5000 km s-1 of the quasar emission-line redshift (three of these four quasars are radio quiet while the other is radio loud). As a result of the original target selection, the small sample of six quasars is unbiased toward finding associated absorption lines. In three of these four cases, the absorption-line optical-depth ratios deviate from the prediction based on atomic physics, suggesting that the background photon source(s) are only partially covered by the absorbing medium and, by extension, that the absorption lines are intrinsic to the quasar. We have used the method of Barlow &Sargent to determine the effective coverage fraction of background source(s) and we have extended it to constrain the coverage fraction of the continuum and broad emission-line sources separately. We have also applied this refined method to the narrow intrinsic absorption lines in three additional quasars for which the necessary data were available from the literature. We find that in two objects from our sample, the continuum source must be partially covered regardless of the covering factor of the emission-line source. We discuss these results in the context of the properties of absorption lines observed in different types of active galaxies and related outflow phenomena. We cannot distinguish between possible mechanisms for the origin of the partial coverage signature, although we do consider possible observational tests. Finally, we speculate on how the gas responsible for the narrow lines may be related to the accretion disk wind that may be responsible for the broad absorption lines observed in some quasars.
Mineralogy and K–Ar geochronology of mixed-layered illite/smectite from The Geysers coring project, California, USA

Clay fractions for K–Ar dating, separated from Franciscan-Assemblage (late Mesozoic) metagraywacke and argillite from The Geysers Coring Project corehole SB-15-D, and a “background” outcrop consist of illite, mixed-layer illite/smectite, mixed-layer chlorite/smectite, and chlorite with minor calcite and quartz. Except for the chlorite/smectite, these phases were formed during both subduction-related Franciscan regional metamorphism and late Cenozoic (post-1.1 Ma) hydrothermal alteration and mineralization related to The Geysers hydrothermal system. The chlorite/smectite is exclusively hydrothermal in origin. In spite of careful efforts to physically separate the metamorphic and layer silicates prior to analysis, all samples contained variable contributions from both sources. The proportion of illite plus illite/smectite clays in the <5 μm fractions of the samples ranges widely from about 41 to 97 wt.%. K2O contents of the dated clay fractions (⩽3 μm) also ranged widely, from 1.66 to 8.0 wt.%. Despite having been heated to at least 300°C, matrix illite and illite/smectite do not show depth- and temperature-dependent trends of downward-increasing illite interlayers as is the case in many old sedimentary basins (e.g. Texas Gulf Coast and North Sea oil fields) and other geothermal systems (e.g. Valles caldera and Salton Sea). Fourteen mixed-layer illite/smectites of different size fractions (0.1–0.35, 0.35–1 and 1–3 μm) from the SB-15-D metagraywackes and argillites (and a nearby “background” sample of the same rock type) yielded K–Ar dates ranging widely from 105.5 Ma (the outcrop sample) to 1.5 Ma. Although there is a general decrease in apparent age with depth, most of the clays yielded middle Tertiary dates (35.4–19.4 Ma). The outcrop age is consistent with published data for Franciscan regional metamorphism. The youngest of the core dates, 2.3 and 1.5 Ma, are slightly older than the earliest Geysers felsite intrusions (1.1 Ma), and substantially older than vein adularia from the corehole (0.57 Ma). Thus, even these youngest illite/smectite dates for the SB-15-D cores likely reflect minor contamination from metamorphic phases. These K–Ar dates do, however, indicate that pre-existing detrital and metamorphic clays have not been totally degassed even though the host rocks have resided in a high-temperature geothermal system for more than a million years. We conclude that the partially reset metamorphic-hydrothermal illite/smectite dates probably reflect the effects of low host-rock permeabilities, of sluggish reaction kinetics of the metamorphic layer silicates, and of “fines migration” of Franciscan Complex clays, along fractures, induced by hydrothermal fluid circulation.
Is Door-to-Balloon Time the Best Metric to Assess Successful Treatment of STEMI?

In 2011, all cardiologists believe that rapid opening of the infarct-related artery is critical to enhanced survival. The preferred way to open an occluded vessel is percutaneous intervention (PCI), but thrombolytic therapy remains a viable option in hospitals when PCI capability is not immediately available. © 2011 Wiley Periodicals, Inc. The author has no funding, financial relationships, or conflicts of interest to disclose.
Prioritizing Highway Safety Manual's crash prediction variables using boosted regression trees

The Highway Safety Manual (HSM) recommends using the empirical Bayes (EB) method with locally derived calibration factors to predict an agency’s safety performance. However, the data needs for deriving these local calibration factors are significant, requiring very detailed roadway characteristics information. Many of the data variables identified in the HSM are currently unavailable in the states’ databases. Moreover, the process of collecting and maintaining all the HSM data variables is cost-prohibitive. Prioritization of the variables based on their impact on crash predictions would, therefore, help to identify influential variables for which data could be collected and maintained for continued updates. This study aims to determine the impact of each independent variable identified in the HSM on crash predictions. A relatively recent data mining approach called boosted regression trees (BRT) is used to investigate the association between the variables and crash predictions. The BRT method can effectively handle different types of predictor variables, identify very complex and non-linear association among variables, and compute variable importance. Five years of crash data from 2008 to 2012 on two urban and suburban facility types, two-lane undivided arterials and four-lane divided arterials, were analyzed for estimating the influence of variables on crash predictions. Variables were found to exhibit non-linear and sometimes complex relationship to predicted crash counts. In addition, only a few variables were found to explain most of the variation in the crash data.
The ijk forms of factorization methods II. Parallel systems

The paper considers the 'ijk forms' of LU and Cholesky factorization on certain parallel computers. This extends an earlier analysis for vector computers. Attention is restricted to local memory systems with processors that may or may not have vector capability. Special attention is given to bus architectures but qualitative analyses are given for other interconnection systems.
Isoenzymatic identification of quantitative traits in crosses between heterozygous parents : mapping tuber traits in diploid potato (Solanum spp.)

Eleven isozyme markers were utilized for quantitative trait loci (QTL) analysis in diploid potato. These markers are distributed among 7 of the 12 chromosomes and therefore give a representative, though sparse, survey of the potato genome. Tuber specific gravity and tuder dormancy were studied. Two segregating diploid populations were constructed from heterozygous self-incompatible parents. These two populations, TRP132 (127 individuals) and TRP133 (110 individuals), have a common maternal parent and combine genomes of Solanum tuberosum (haploid), S. chacoense, and S. phureja. The populations were planted at two locations in Michigan in 1990 using a randomized complete block design with three replications per location. After harvest they were characterized with the isozymes and evaluated for specific gravity and tuber dormancy. To test for QTLs, one-way analyses of variance were conducted for each locus by trait combination. Significant associations between markers and quantitative trait variation were identified, which accounted for a range from 4% to 15% of the phenotypic variation for specific gravity, and from 4.5% to 20.4% for tuber dormancy. Two-way analyses of variance between significant markers were used to identify epistatic interactions between markers. Multiple regression analyses were used to estimate the overall effect of the significant markers on the phenotypic variation for these traits. These values ranged from 15.3% and 32.3% for specific gravity. For dormancy, the significant loci accounted for 8.5% and 36.9% of the total phenotypic variation for each of the populations. We find that isozyme analysis is a useful tool for preliminary QTL studies in potato.
Degree of consistent training: Improvements in search performance and automatic process development

Previous research has shown substantial improvements in detection performance when subjects consistently detect a subset of stimuli. In contrast, in conditions in which stimuli appear as both targets and distractors, there is little performance improvement with practice. The present experiments examine how varying degrees of consistency determine the improvement of detection accuracy with extended practice. The degree of consistency was varied by manipulating the frequency with which a letter was a distractor while holding the number of occurrences as a target constant. The experiments utilized a multiple-frame target-detection search paradigm in which subjects were to detect single-letter targets in a series of rapidly presented letters on four channels. Experiments showed that detection performance improvement with practice was a monotonic function of the degree of consistency, decreasing to zero as the target-to-distractor ratio increased from 10:0 to 10:20. As consistency decreased, detection performance asymptoted earlier and at a lower level. A dual-task experiment examined subjects’ ability to perform the previously trained search task as a secondary task. Results showed that the previous targetto-distractor consistency had a marked effect on resource sensitivity of the detection task. The general issues of consistency in the development of skilled performance and in the development of automatic processing are discussed.
Outpatient management of the burn patient

Data from the National Burn Repository 2002 report indicate that most burns are minor and that 80%, to 90% of burn injuries can be treated on an outpatient basis. This article discusses the assessment and outpatient management of burn injuries, the role of specialized burn centers, and the reimbursement for outpatient burn care.
An examination of how student journalists seek information and evaluate online sources during the newsgathering process

A thorough understanding of how to evaluate website credibility is a crucial tool for journalists. This study examines how journalism students conduct the online newsgathering process and seeks to understand the decisions they make involving credibility assessment. This was accomplished through a triangulated approach involving a content analysis of video recordings of students’ keystrokes during the newsgathering process, coupled with subsequent semi-structured interviews. The findings suggest that while journalism students exhibit some level of understanding about the importance of verification, they rely strongly on search engines and trust the credibility of search-engine results.
Initiative to Improve Process Representation in Chemistry‐Climate Models

The Atmospheric Chemistry and Climate Initiative (AC&C) will address the current large uncertainties in our understanding of chemistry-climate interactions for short-lived atmospheric chemical constituents (e.g. aerosols, ozone, and methane). Understanding what controls the distribution of these species, how they affect climate, and how their distributions might change with a changing climate are important for air quality and climate forecasts. AC&C will address this issue in its first phase through a series of modeling exercises designed to test models’ ability to reproduce observed changes in these species distributions, to produce a set of coordinated forecasts for their future distribution, and to understand how processes are represented in different models. Observational databases will be used to test the models and to better understand processes represented in the models. This article describes the plans for this first phase of activities and seeks participation from the research community.
The Prevention of World War III: A Psychological Perspective

I will start with a Jewish proverb and then will come to a Jewish story. First the proverb: an insincere peace is better than a sincere war.
Seasonal effects on osmotic permeability of Rana pipiens in vivo and in vitro

Dependence on season of the osmotic water permeability (Lp) of the skin of whole frogs and isolated preparations of frog leg and abdominal skin have been determined. The Lp of frog skin in vivo and in vitro increases during the summer. However, the increase in vivo occurs in April while the increase in vitro does not occur until August. Injection of arginine vasopressin (ADH) into whole frogs in July produces a 200% increase in the osmotic water permeability, while the same injection in March induces only a slight increase. Isolated abdominal skin shows a similar effect upon stimulation by 500 mU/ml of ADH: a large increase in July with a barely detectable effect in March. Isolated leg skin does not show a response to this level of vasopressin either in July or March. The possibility that seasonal changes in the osmotic permeability of whole animals can be attributed to seasonal variations in sensitivity to ADH is discussed.
Robust non-intrusive record-replay with processor extraction

With the advent of increasingly larger parallel machines, debugging is becoming more and more challenging. In particular, applications at this scale tend to behave non-deterministically, leading to race condition bugs. Furthermore, gaining access to these large machines for long debugging sessions is generally infeasible. In this paper, we present a 3-step algorithm to perform what we call "processor extraction": a procedure to record the execution of a set of processors from a parallel application, and replay any of them in a controlled environment. Our technique generates very low interference in the recorded program thanks to the separation between non-determinism elimination, and detailed processor recording. In order to improve robustness and accuracy, we further augmented our algorithm with a self-correction mechanism.
Taxes versus Fees: Lead Paint and LLCs

This paper discusses the rather blurred distinction between fees and taxes, particularly for states like California where enactment of a tax requires a two‐thirds vote while fees can be enacted with a simple majority. We discuss the California Supreme Court decision in Sinclair Paint wherein the Court adopted a broad definition of a fee. Many taxpayers feared that this would open the flood gates for enactment of fee legislation both in California and nationwide. We examine recent legislative and judicial trends in enactment of fee legislation and court interpretations following Sinclair Paint. The data shows that the Legislature is actively pursuing all types of fee legislation as budget dollars do not stretch far enough to cover program expenditures. Courts are continuing the Sinclair Paint trend of broadly defining fees. The result seems to be an ever increasing fee burden on businesses and taxpayers.
High 2-deoxy-2-[18F]fluoro-D-glucose accumulation in a case of retroperitoneal fibrosis following resection of carcinoid tumor.

Positron emission tomography (PET) using 2-deoxy-2-[18F]fluoro-D-glucose (FDG) has been shown to be a highly sensitive diagnostic tool to stage, restage, and monitor the progress of various neoplasms. A number of physiological and non-neoplastic conditions, however, also may be associated with focal accumulation of FDG and can cause false-positive results. This work reports a 52-year-old man who had marked FDG accumulation in carcinoid tumor of the distal ileum. The tumor was resected. A follow-up FDG-PET scan one and a half years later revealed intense FDG accumulation in the abdominal periaortic region, suggesting recurrent malignancy. Computerized tomography (CT) of the abdomen showed soft tissue mass surrounding the aorta. Fine-needle aspiration biopsy of the periaortic soft tissue confirmed benign retroperitoneal fibrosis. This case shows that retroperitoneal fibrosis can cause intense FDG accumulation giving false impression of malignancy. In interpretation of whole-body FDG-PET, various physiological and benign causes of FDG accumulation must be considered in order to avoid pitfalls. The authors have reviewed the literature and discussed association of carcinoid tumor and retroperitoneal fibrosis. (Mol Imag Biol 2002;4:363–368)
Day 3 serum inhibin-B is predictive of assisted reproductive technologies outcome

Objective: To determine if women with day 3 serum inhibin-B concentrations Design: Analysis of inhibin-B, FSH, and E 2 concentrations in day 3 serum samples. Setting: Academic clinical practice. Patient(s): One hundred fifty-six women who underwent 178 assisted reproductive technology (ART) cycles with luteal phase GnRH agonist suppression plus hMG and urofollitropin stimulation. Main Outcome Measure(s): Serum E 2 on day of hCG, number of oocytes retrieved per patient, fertilization rate, cleavage rate, clinical pregnancy rate (PR) per initiated cycle, cancellation rate per initiated cycle, and spontaneous abortion rate. Result(s): Women with day 3 serum inhibin-B 2 response, had 66.6% of the number of oocytes retrieved per patient, with 28% of the clinical PR per initiated cycle, and three times the cancellation rate per initiated cycle than women with day 3 inhibin-B ≥ 45 pg/mL. After controlling for age, day 3 serum FSH, day 3 serum E 2 , patient cycle number, and method of ART, day 3 serum inhibin-B ≥ 45 pg/mL was noted to be prognostic of the number of oocytes retrieved and clinical PR. The adjusted odds ratio of clinical pregnancy for those with day 3 serum inhibin-B ≥ 45 pg/mL versus those with inhibin-B Conclusion(s): Women with low day 3 serum inhibin-B concentrations demonstrate a poorer response to ovulation induction and are less likely to conceive a clinical pregnancy through ART relative to women with high day 3 inhibin-B.
CONGENITAL PULMONIC STENOSIS COMPLICATING EBSTEIN'S ANOMALY OF THE TRICUSPID VALVE.

Abstract Clinical, hemodynamic and angiocardiographic observations are presented in the case of a 4 1 2 year old boy believed to have the unique combination of congenital pulmonic stenosis with Ebstein's anomaly of the tricuspid valve. The diagnosis was initially considered because clinically evident pulmonic stenosis was present with gross right atrial enlargement but with conspicuous absence of right ventricular hypertrophy. Aneurysmal dilatation of the left pulmonary artery was a feature of additional interest. Clinical suspicion demanded the use of the electrode catheter which confirmed the diagnosis of Ebstein's anomaly and distinguished it from congenital hypoplastic right ventricle.
The role of gas resources in Mexico: Opportunities for the 21st century

The Mexican gas basins have played an important role in the energy industry as well as providing strategic investment opportunities. In 1999 Mexico produced about 1.29 Tcf of natural gas, consuming 1.26 Tcf. Pemex had the exclusive function for the transportation and storage of natural gas. With the new reforms, new laws permit private participation in these activities. Considerable increases in production can be observed in different fields of the northern region, making this the most important gas province in Mexico. Pemex is planning to improve the production in all its facilities for the next 10 years with new technology and strategic procedures, and is contemplating exploration and development in Sabinas, Burgos, exploration offshore Burgos, exploration at Sierra Madre, and exploration and development in Veracruz and southern basins.
Introduction to the U.S. congressional budget process

Abstract The formulation of the budget is one of the most important and time-consuming tasks of the U.S. Congress. As a result, the budget process also produces a great deal of published information. This article explains the important basic budget concepts, describes the major steps in the congressional budget process, and identifies the publications produced by the process. An annotated list of other important budget-related publications is included.
Incomplete Factorial and Response Surface Methods in Experimental Design: Yield Optimization of tRNATrp from In vitro T7 RNA Polymerase Transcription

We have studied the yield of Escherichia coli tRNA(Trp) obtained from in vitro T7 RNA polymerase transcription using incomplete factorial and response surface methods. Incomplete factorial experiments were first used to estimate the relative impact of six variables on the yield of tRNA(Trp). Fifteen trials were performed according to a balanced and randomized design. The correlation between observed yield and all experimental variables was identified by stepwise multiple linear regression analysis. The concentrations of T7 RNA polymerase, DNA template, NTP and MgCl2 proved to be significantly correlated with the yield of tRNA(Trp). We then optimized the yield with respect to each of these four variables simultaneously with a designed, response surface experiment based on the Hardin-Sloane minimum prediction variance algorithm. Twenty experiments were performed, in duplicate, to sample the quadratic surface relating the yield to the four significant variables. Coefficients of the quadratic function with all two-factor interactions were evaluated by stepwise regression using least squares, and significant coefficients were retained. Partial differentiation of the resulting quadratic model showed it to possess an optimum. Transcription performed at the corresponding conditions yielded 6-fold more tRNA(Trp) than the initial conditions, confirming the predictive value of the experimentally determined response surface.
Functional MRI impulse response for BOLD and CBV contrast in rat somatosensory cortex.

The contrast mechanism in functional MRI (fMRI) results from several vascular processes with different timescales, thus establishing a finite temporal resolution to fMRI experiments. In this work, we measured the BOLD and the iron-oxide-derived cerebral blood volume (CBV) impulse response (IR) in a rat model of somatosensory brain activation at 11.7T. A binary m-sequence probe method was used to obtain high sensitivity single-pixel estimates of the IR, from which two parameters, the full-width-at-half-maximum (FWHM) and the time-to-peak (TTP) were determined as indices of the temporal resolution of the hemodynamic responses. Results (n=11) show that the CBV IR (n=5, subset) is significantly narrower (FWHM = 1.37 ± 0.11s), and peaks earlier (TTP = 1.65 ± 0.15s) than the BOLD IR (n=11, FWHM = 1.92 ± 0.22s and TTP = 2.18 ± 0.14s, respectively). These results indicate that neurovascular control mechanisms have a temporal resolution better than 1.5s FWHM, and point to a substantial contribution to BOLD of the dispersive transit of oxygenated hemoglobin across the rat vasculature, bringing important implications for the ultimately attainable temporal resolution of fMRI.
The Structure ofĪ ⊗ Λnin Generic Representation Theory☆

Abstract This paper pursues a study of the category F of functors between F 2-vector spaces. It is proved that the objects I ⊗ Λ n occur in short exact sequences K n → I ⊗ Λ n → K n − 1 , where each K n is a non-finite functor, which has the property that every proper sub-functor is finite. Moreover, every sub-functor of I ⊗ Λ n either contains K n or is finite.
The changing readability of introductory political science textbooks: A case study of Burns and Peltason, "Government by the People"

It has been standard wisdom among academic professionals for several decades that educational standards in post-secondary institutions are declining: grade inflation, fewer written assignments, and less demanding syllabi are aspects of the typical complaint. Students, too, have come in for questioning. Their preparation for college work on a number of levels has been found wanting. At the post-secondary level, however, a gap remains in the literature of our discipline: what about the curriculum? Most of the attention to this question has been directed at the technicalities of teaching theory and empirical knowledge (Cushman 1993; Jordan and Sanchez 1994; Luna and McKenzie 1997; Opheim and Stouffer 1997). However, the substance of the curriculum itself—the textbooks that most of us use at least in our introductory-level courses—have not received a full examination. From the past 15 years, several articles have been published in this journal on various aspects of textbooks as teaching tools, including their prejudices, their effectiveness, or their ideological content (Goldstein 1985; Sanchez 1996); there has also been a puzzling lacuna. There is a quiet but oft-repeated suspicion in the profession that textbooks are not what they used to be—they do not have as much substantive or theoretical content, they are increasingly video-driven, and less space is dedicated to argument and information. We found nothing from the most recent 15-year period of PS publications that remotely addresses this question. Given common perceptions—correct or not—about the deterioration of student ability (and there are articles in recent issues of this journal about that topic), it is remarkable that textbooks have not been subjected to a parallel scrutiny within our profession. There are many reasons to consider the change in quality of textbooks over time: they are a core part of our instructional resources; writing them is frequently considered a part of our “research” activity; and, they are a primary way of introducing students (including potential members of our profession) to the discipline of political science. While there are many ways to measure change, we limit our focus in this preliminary study to the accessibility of written materials, to the increase or decrease in the readability of introductory texts over the past several decades. Readability is one measure of accessibility, making it a key factor in communicating ideas and ultimately in teaching political science.
Seismic reflection profiling across Tertiary extensional structures in the eastern Amargosa Desert, southern Nevada, Basin and Range province

Outcrops, shallow well control, and coincident geophysical surveys are used to interpret a seismic reflection profile in the Amargosa Desert, within the Basin and Range province, of southern Nevada. The east-west-trending, 27-km-long seismic line crosses all or parts of three Tertiary subbasins, revealing that basin growth occurred by progressive shifts of basin-bounding faults. The reflection line images Tertiary strata that is rotated by steeply dipping listric faults and that noses into normal faults. A shallow (less than 100 to 200 m deep), laterally continuous, flat-lying, low-frequency reflector, interpreted as a Tertiary basalt flow, suggests that little vertical deformation has occurred within the easternmost of the small Tertiary basins since the eruption of the flow about 10 million years ago. Moderately dipping reflections within the pre-Tertiary bedrock may image Mesozoic thrust faults. The reflection data indicate that, whereas the top of the reflective lower crust shallows to the west, possibly in the direction of increasing crustal extension, the Moho is relatively flat between 30 and 33 km deep. Apparent bright-spot reflections from the lower crust are interpreted as evidence for ductile shearing of the lower crust, not for active magma chambers. Doming of the lower crust resembles that observed elsewhere in the Basin and Range province and is consistent with ductile flow in the lower crust.
Materials problems in coal gasification and liquefaction

The conversion of coal to “clean” fuels imposes severe demands on materials of construc-tion. The operational environments experienced by these materials may be high tempera-tures and high pressures and contain substantial quantities of H2S, H2, organic acids, chlorides and particulate matter. Experiences to date indicate that corrosion and erosion problems will tax materials engineers and designers. This paper discusses material prob-lem areas and requirements that have been identified for coal conversion plants. A sum-mary of critical material selection areas for coal gasification and liquefaction plants is given.
Prevalence of hyponatremia, renal dysfunction, and other electrolyte abnormalities among runners before and after completing a marathon or half marathon

Since its inception in 490 bc,48 the marathon has been an amazing human accomplishment. Recently, participation in marathons and half marathons has gained increasing popularity for a variety of reasons, including the presumed health benefits and the importance of exercise in daily routines.38 Along with this increasing involvement of the general population in marathons, reports have surfaced regarding the injuries and illnesses associated with distance running.47 The most frequent medical complications described in distance exercise are related to hyponatremia.42 Excess hydration with water has been linked to hyponatremia,† although it is uncertain whether this is from hydration before the race or during the race. With progression of exercise-associated hyponatremia, adverse events can occur, including altered sensorium, seizures, pulmonary edema, and even death.4,23,44,53 However, it is unclear from these studies whether and to what degree hyponatremia is present prerace. The role of hydration in physical activity has been investigated in a variety of studies.‡ The American College of Sports Medicine supports the concept that the salt content of the hydration beverage is an important consideration during physical activity.8 Unfortunately, blanket guidelines on the type or amount of fluid to prevent hyponatremia or renal dysfunction are not possible, given the wide variability in individual sweat rates and renal water excretion, in addition to the range of environmental conditions possible on race day.20 The limitations of prior studies on endurance activity are threefold: Sample sizes are frequently small§; prerace parameters are not measured‖; and sodium is frequently the only reported electrolyte.2,4,9,14,28,32 Additionally, many earlier studies were based on the performance of elite athletes or individuals presenting for medical attention. The associations developed from these data must be critically evaluated in light of these weaknesses. By collecting blood samples in the prerace environment, any preexisting hematologic or electrolyte disturbances that may increase susceptibility to metabolic derangements in the postrace setting can be identified. Continuing data collection in the postrace setting with parallel blood measures allows detection of changes. These analyses, as set in a large participant population and in persons not necessarily presenting for acute medical attention, are intended to more accurately describe the metabolic effects of participating in distance running.
Mezlocillin, ceftizoxime, and amikacin alone and in combination against six Enterobacteriaceae in a nentropenic site in rabbits

Closed-space, locally neutropaenic infection sites were simulated in rabbits by implanting subcutaneous semipermeable chambers inoculated with 5 X 10(4) cfu/ml of Escherichia coli (one strain), Citrobacter diversus (one strain), Klebsiella pneumoniae (two strains) or Serratia marcescens (two strains). Four hours after inoculation, treatment was begun with amikacin (15 mg/kg), mezlocillin (100 mg/kg), or ceftizoxime (50 mg/kg) alone or in two-drug combinations. Antibiotics were given intramuscularly every 6 h for 16 doses. Chambers were sampled for bacterial counts at the start of therapy, and 20, 44, and 92 h thereafter. Blood and chamber antibiotic levels were determined during the treatment course. In-vivo results were compared to in-vitro tests of inhibition, killing and synergism. Ceftizoxime alone was successful in vivo (greater than 6 log reduction in count) against the three strains of klebsiella and citrobacter, mezlocillin against one serratia strain, and amikacin alone against none of the strains. The best in-vitro correlation was with the minimum inhibitory concentration (MIC) at a high (10(8] inoculum for the beta-lactams and with the anaerobic MIC for amikacin. Among combinations, amikacin plus mezlocillin alone was successful against the three strains of klebsiella and serratia, but neither amikacin nor mezlocillin added to ceftizoxime were more successful than ceftizoxime alone. In-vitro chequerboard synergism was not predictive of in-vivo success. Mezlocillin alone was inactivated in vivo by all the strains except Ser. marcescens, and the E. coli strain inactivated both mezlocillin and ceftizoxime alone and in combination.
Disturbance in cerebral spinal fluid sphingolipid content is associated with memory impairment in subjects infected with the human immunodeficiency virus

Despite widespread use of antiretroviral therapies to control replication of the human immunodeficiency virus (HIV), dysfunctions of cognition that are collectively termed HIV-associated neurocognitive disorders (HAND) still occur in approximately 50% of those infected by the virus. Currently there is not a biomarker that can identify HIV-infected people who are at risk for the development of HAND. Previous studies have identified particular sphingolipid species that are dysregulated in HAND, but the neurocognitive correlates of these biochemical findings are not currently understood. To address this question, we compared cerebrospinal fluid (CSF) levels of sphingomyelin, ceramide, and sterol species with performance on standard neurological tests designed to assess the function of multiple cognitive and motor domains in HIV-infected subjects. We found that sphingomyelin:ceramide ratios for acyl chain lengths of C16∶0, C18∶0, C22∶0, and C24∶0 were associated with worse performance on several indices of memory. The most striking finding was for the acyl chain of C18∶0 that consistently associatedwith performance onmultiple tests of memory. These findings suggest that the sphingomyelin:ceramide ratio for C18∶0 may be a reasonable surrogate marker for memory dysfunction in HIV-infected subjects.
Reassessing the Oil Security Premium

World oil supply disruptions lead to U.S. economic losses. Because oil is fungible in an integrated world oil market, increased oil consumption, whether from domestic or imported sources, increases the economic losses associated with oil supply disruptions. Nevertheless, increased U.S. oil production expands stable supplies and dampens oil price shocks, whereas increased U.S. oil imports boosts the share of world oil supply that comes from unstable producers and exacerbates oil price shocks. Some of the economic losses associated with oil supply disruptions - gross domestic product losses and some transfers abroad - are externalities that can be quantified as oil security premiums. To estimate such premiums for domestic and imported oil, we take into account projected world oil market conditions, probable oil supply disruptions, the market response to oil supply disruptions, and the resulting U.S. economic losses. Our estimates quantify the security externalities associated with increased oil use, which derive from the expected U.S. economic losses resulting from potential disruptions in world oil supply.
Surgical and other invasive approaches to recurrent pleural effusion with malignant etiology

With an increasing number of cancer survivors, the annual incidence of malignant pleural effusions has been rising in recent decades worldwide. Many patients with various forms of cancer develop malignant pleural effusions at some point in their life. Patients most commonly present with progressive dyspnea. These effusions are refractory and are associated with impaired quality of life for these patients. The main goals of management are evacuation of the pleural fluid and prevention of its re-accumulation. The therapy plan should consider the general health of the patients, their performance status, the presence of trapped lung, and the primary malignancy. However, there is no universally established, standard approach. Surgical options include thoracentesis, chest tube drainage, thoracoscopy followed by chemical and mechanical pleurodesis, Pleur-X catheter drainage, and pleurectomy. Chemical pleurodesis is the most common modality of therapy for patients with recurrent pleural effusion. For example, Talc is the most successful pleurodesis agent with similar equal to that of poudrage or slurry. Pleur-X catheter can reduce hospital stay and adds value to the treatment of patients with trapped lung, who are not appropriate candidates for pleurodesis. Furthermore, a mechanical pleurodesis has been shown to be effective particularly in pleural effusions with lower pH. This article reviews the surgical and other invasive options as well as their technical aspects in the management of recurrent malignant pleural effusions.
US-Based Drug Cost Parameter Estimation for Economic Evaluations

Introduction. In the United States, more than 10% of national health expenditures are for prescription drugs. Assessing drug costs in US economic evaluation studies is not consistent, as the true a...
Substance P and cholecystokinin-like immunoreactive varicosities in somatosensory and autonomic regions of the rat spinal cord: a quantitative study of coexistence.

Substance P- and cholecystokinin-like immunoreactivities have been shown to coexist in some, but not all, dorsal root ganglion cell bodies of the rat. Quantitative immunofluorescence techniques were used in the present study to describe densities of substance P- and cholecystokinin- like immunoreactive varicosities in several spinal cord nuclei. By combining simultaneous immunofluorescent techniques on one tissue section with computerized image processing, coexistence of substance P- and cholecystokinin-like immunoreactivity in varicosities was also quantified. By comparing spinal cord regions between normal and unilateral dorsal rhizotomy affected animals, densities of substance P- and cholecystokinin-like immunoreactive varicosities associated with primary afferent neurons were established. To determine the densities of immunoreactive varicosities that were related to unmyelinated primary afferent fibers, data were compared between normal animals and those treated neonatally with capsaicin. Four major observations were made: (1) Substance P- and cholecystokinin-like immunoreactivity coexist in populations of varicosities in sensory and autonomic regions of rat spinal segment L6. (2) Within the superficial laminae of the dorsal horn, varicosities containing both substance P- and cholecystokinin-like immunoreactivity and cholecystokinin-like immunoreactivity alone are of primary afferent neuron origin, but those containing only substance P-like immunoreactivity are most likely of spinal or descending neuronal origin. (3) Capsaicin-insensitive cholecystokinin-like immunoreactive varicosities were present predominantly in lamina I. These data suggest some cholecystokinin-like immunoreactive varicosities are associated with myelinated primary afferent neurons. (4) Primary afferent fibers containing substance P- and cholecystokinin-like immunoreactivity project to intermediate gray regions of the rat spinal cord. A large proportion of these fibers are capsaicin sensitive, suggesting that they are unmyelinated.
Socioeconomic Conditions and Property Crime: A Comprehensive Review and Test of the Professional Literature

. A comprehensive review of the crime literature indicates varying and often opposing hypotheses of relationships between property crime and socioeconomic conditions such as poverty, business cycle conditions, demographics, criminal justice system actions, and family structure. Employing measures of each of the hypothesized factors, time-series models for robbery, burglary, and vehicle theft are estimated from yearly and national Uniform Crime Report (UCR) data for the period 1959 through 1992 and are used to test these hypotheses' current empirical relevance. The empirical findings selectively confirm the importance of macroeconomic stability and criminal justice system actions in reducing property crime activity. In contrast, decreases in absolute poverty and general income inequality are associated with increased criminal activity; and age demographics and family/community structure apparently have little impact on any of the analyzed property-crime trends, A reduction in inflation apparently decreases property crimes.
Laser intensity fluctuations when the photon number at threshold is small

Abstract Previous calculations of laser threshold statistics have described the radiation field with a Fokker-Planck equation that embodies the approximation that the photon number at threshold is large. Here, the magnitude and correlation time of intensity fluctuations are calculated directly from the Scully-Lamb equation of motion for the reduced density matrix of a single-mode laser. This model does not embody a restriction to large photon number at threshold. We delineate the regime in which the threshold photon number is sufficiently small to produce measurable differences from the results of the usual Fokker-Planck analysis.
The measurement of nanogram amounts of acetylcholine in tissues by pyrolysis gas chromatography.

— A method previously described for measuring ACh in biological effluents has been simplified and extended for use with tissues. The tissue is homogenized in acetonitrile containing propionylcholine as the internal standard and after centrifugation the acetonitrile is removed by shaking with toluene. To the aqueous solution is added a solution of KI-I2 to precipitate the quaternary compounds. The precipitate is dissolved in aqueous acetonitrile and then drawn through a small column of ion-exchange resin to convert the periodides of the quaternary compounds to chlorides which are then simultaneously pyrolysed and gas chromatographed. On the column the pyrolytic product of choline has a slower retention time than that of acetylcholine; under these circumstances the choline present in tissues does not obscure the measurement of acetylcholine. Specificity was demonstrated by several procedures including mass spectroscopy. The method can measure 25 ng (171 pmoles) of acetylcholine in extracts of brain, simply, and with high reproducibility. With the usual gas chromatograph, 16 samples can be run in a working day. The content of acetylcholine in rat brain was 26.4 nmol/g or almost precisely the values found with other gas chromatographic methods. The pyrolytic method was shown to be applicable to the detection of biologically interesting substances other than choline esters, including betaine, carnitine and the non- quaternary compound, ź-aminobutyric acid, which is readily converted to a volatile compound (probably its methyl ester) when pyrolysed in the presence of tetramethylammonium hydroxide. Of additional general interest is the demonstration of the advantages of acetonitrile as a solvent for extracting water-soluble compounds from tissues.