cssi/SciSciGPT-SciSciNet huggingface dataset:
Arsenic transport in groundwater, surface water, and the hyporheic zone of a mine-influenced stream-aquifer system

[1] We investigated the transport of dissolved arsenic (As) in groundwater, surface water, and the hyporheic zone of a stream-aquifer system influenced by an abandoned arsenopyrite mine. The weathering of unconsolidated aquifer materials, derived from mine waste piles, consists of As-bearing minerals including arsenopyrite, scorodite, and iron oxides, providing a continuous source of As to water. Arsenic loads from the stream, springs, and groundwater were quantified at the study reach on nine dates from January to August 2005, and a mass balance approach was used to determine hyporheic storage of As. Loading from groundwater was the dominant source of As to the stream, while loads from springs represented a substantial proportion of the As load during spring. Arsenic loads in surface and groundwater were significantly elevated during summer despite lower discharge; groundwater load was positively correlated to aquifer temperature. The hyporheic zone retained As in the upstream-most subreach, most likely through the adsorption of As onto hyporheic sediments. In downstream subreaches, hyporheic sediments, derived from mine-tailing piles of high As content, were sources of As to the stream. Spatial variation in sediment source and composition reflecting flood transport from upstream and mass wasting of mine tailings, along with temporal changes in hydrology, combine to dictate the role of the hyporheic zone in the transport and retention of As.
Validation of a neighborhood SES index in a managed care organization.

BACKGROUND/OBJECTIVE Neighborhood socioeconomic status (SES), beyond individual SES, has been associated with health behaviors and outcomes. We constructed a neighborhood SES index using readily available US Census variables and studied associations of the index with self-reported education, formal education, and neighborhood residential characteristics among adult enrollees of a managed care organization (MCO). METHODS A neighborhood SES index was constructed for MCO enrollees using a principal components analysis of 7 Census measures of their residential tracts or block groups. Quartiles of resulting neighborhood SES scores were matched with self-reported education, household income, and neighborhood residential characteristics obtained on 3 surveys of MCO adults ranging in age from 18 to 99. Cross-tabulations of neighborhood SES with self-reported measures were used to assess concordance. RESULTS Consistent with other non-MCO populations, distributions of the neighborhood SES index and self-reported education, household income, and other neighborhood residential characteristics were concordant. The presence of high SES MCO enrollees in low SES neighborhoods and low SES MCO enrollees in high SES neighborhoods was, however, common. MCO enrollees living in low SES neighborhoods also reported neighborhood problems (crime, unattended dogs) known to affect walkability more frequently than those living in high SES neighborhoods. CONCLUSIONS A simple, valid neighborhood SES index can be constructed for MCO populations using readily available US Census variables. Although individual and neighborhood SES are on average concordant, discrepancies between individual and neighborhood SES suggest that other factors may influence how area-based SES contributes to health behaviors and outcomes in an MCO population.
Transient kinetic studies of substrate inhibition in the horse liver alcohol dehydrogenase reaction

Abstract The rate-limiting step of ethanol oxidation by alcohol dehydrogenase (E) at substrate inhibitory conditions (>500 m m ethanol) is shown to be the dissociation rate of NADH from the abortive E-ethanol-NADH complex. The dissociation rate constant of NADH decreased hyperbolically from 5.2 to 1.4 s −1 in the presence of ethanol causing a decrease in the K d of NADH binding from 0.3 μ m for the binary complex to 0.1 μ m for the abortive complex. Correspondingly, ethanol binding to E-NADH ( K d = 37 mm) was tighter than to enzyme ( K d = 109 mm). The binding rate of NAD + (7 × 10 5 m −1 s −1 ) to enzyme was not affected by the presence of ethanol, further substantiating that substrate inhibition is totally due to a decrease in the dissociation rate constant of NADH from the abortive complex. Substrate inhibition was also observed with the coenzyme analog, APAD + , but a single transient was not found to be rate limiting. Nevertheless, the presence of substrate inhibition with APAD + is ascribed to a decrease in the dissociation rate of APADH from 120 to 22 s −1 for the abortive complex. Studies to discern the additional limiting transient(s) in turnover with APAD + and NAD + were unsuccessful but showed that any isomerization of the enzyme-reduced coenzyme-aldehyde complex is not rate limiting. Chloride increases the rate of ethanol oxidation by hyperbolically increasing the dissociation rate constant of NADH from enzyme and the abortive complex to 12 and 2.8 s −1 , respectively. The chloride effect is attributed to the binding of chloride to these complexes, destabilizing the binding of NADH while not affecting the binding of ethanol.
Are global sufficient statistics always sufficient: The impact of quantization on decentralized data reduction

The sufficiency principle is the guiding principle for data reduction for various statistical inference problems. There has been recent effort in developing the sufficiency principle for decentralized inference with a particular emphasis on studying the relationship between global sufficient statistics and local sufficient statistics. We consider in this paper the impact of quantization on decentralized data reduction. The central question we intend to ask is: if each node in a decentralized inference system has to summarize its data using a finite number of bits, is it still sufficient to implement data reduction using global sufficient statistics prior to quantization? We show that the answer is negative using a simple example and proceed to identify conditions when global sufficient statistics based data reduction is indeed optimal. They include the well known case when the data at decentralized nodes are conditionally independent as well as a class of problems with conditionally dependent data.
“Standing on the Promises that Cannot Fail”: Evaluating the Black Church’s Ability to Promote Community Activism Among African-Americans in the Present Day Context

The black church was the most important institution in the African-American community before the civil rights movement. Using data from the 1996 National Black Election Study, this research examines the role of religiosity in encouraging community activism among contemporary black Americans in the modern era. The findings suggest that a delineation between politicized and non-politicized churches facilitates an understanding of community activism among black Americans.
Strategic Planning and Budgeting to Achieve Core Missions.

A new strategic plan, an additional one hundred faculty members, a new financial model, an incentive compensation plan, a new $200 million research building, closing one professional school and repositioning assets to help another, redirecting net revenues from two parking garages, and a building renewal and replacement plan-all are outcomes of a strategic planning and budgeting process.
Estradiol plus progesterone promote glutamate-induced release of γ-aminobutyric acid from preoptic area synaptosomes

Abstract Treatment of ovariectomized rats with both estradiol and progesterone in vivo resulted in a marked enhancement of glutamate-induced release of newly synthesized [ 3 H]γ-aminobutyric acid (GABA) from synaptosomes of the preoptic area in vitro . With this treatment, as little as 0.01 mM glutamate, in vitro , enhanced release of GABA. In contrast, glutamate, in vitro , did not stimulate release of GABA from synaptosomes, obtained from rats treated with either estradiol or progesterone alone and only large concentrations of glutamate (1.0 and 10 mM) caused a modest release of GABA from synaptosomes from ovariectomized, vehicle-treated rats. Also, treatment with estradiol plus progesterone did not alter glutamate-induced release or exchange of [ 3 H]glutamate. Glutamate-induced release of GABA was calcium-independent and attenuated by the putative chloride channel antagonist, 4,4'-diisothiocyanatostilbene-2, 2'- dl -disulfonic acid. Thus, glutamate-induced, steroid-enhanced release of GABA may occur through a chloride-dependent carrier rather than by exocytosis. In addition to enhancement by glutamate, release of GABA was also enhanced by d -aspartate, an agent that is transported by the neuronal glutamate carrier. It is postulated that enhancement of glutamate-induced release of GABA, by estradiol plus progesterone in the preoptic area, represents one process by which these steroids modulate reproductive function in female rats.
Television at large

All the essays in this special issue deal with the theme Television at large in the political, economic, cultural, and technological contexts of contemporary South Asia. In different ways, each ess...
Regulation of bright-colored pigmentation of amphibians

Abstract Bright integumental pigmentation of amphibians is imparted by the action of reflecting pigment cells (iridophores), yellow pigment cells (xanthophores), or red pigment cells (erythrophores). Iridophores are sensitive to intermedin and respond by concentrating their pigment. Common features of the intermedin molcule are involved in the stimulation of both iridophores and melanophores. The purines, guanine, hypoxanthine, and adenine are the primary iridophore pigments and are found in discrete organelles, the reflecting platelets. Intermedin markedly affects the form of reflecting platelets as well as the amounts of purine they contain. Xanthophores and erythrophores contain pteridine and carotenoid pigments. Pteridines are found within an organelle, the pterinosome, a spheroid approximately 500 mμ in diameter, formed by a series of concentric lamellae. Carotenoids appear to be contained in droplets interspersed between the pterinosomes. Migration of pigment within xanthophores is not generally controlled by intermedin although such may be the case in adult Hyla arenicolor . The carotenoid content of skin is higher in normal larvae than in hypophysioprivic larvae. Pteridine content of xanthophores is much higher in normal larvae than in hypophysioprivic larvae. Pteridine content of xanthophores is much higher in normal larvae than in hypophysioprivic animals. In the latter, administration of intermedin elevates pteridine levels. Profound changes in pteridine content occur at metamorphosis under the direct control of thyroxine. Adult amphibians which can change their colors rapidly, do so by means of a group of dermal chromatophores constituting the “dermal chromatophore unit”. Cytological and endocrinological relationships of the unit are discussed in terms of color change mechanisms.
Quantitative Reasoning Learning Progression: The Matrix

The NSF Pathways Project studied the development of environmental literacy in students from grades six through high school. Learning progressions for environmental literacy were developed to explicate the trajectory of learning. The Pathways QR research team supported this effort by studying the role of quantitative reasoning (QR) as a support or barrier to developing environmental literacy. An iterative research methodology was employed which included targeted student interviews to establish QR learning progression progress variables and elements comprising those progress variables, development of a QR learning progression framework, and closed-form QR assessments to verify the progression. In this paper the focus is on development of the current iteration of the QR learning progression, including a brief discussion of the first and second iterations that provide a look into the development of a learning progression. The focus is on the latest iteration, with a detailed discussion of the progress variables: Quantitative Act (QA), Quantitative Interpretation (QI), and Quantitative Modeling (QM). The elements that constitute these progress variables which arose from our analysis of qualitative interview data and quantitative assessment data are provided. Discussion of the evolution of the QR assessment to document students’ abilities to utilize the progress variables occurs concurrently with explanation of the learning progression development. The most recent QR assessment focused on QI. The data from this assessment will provide additional information to revise the learning progression QI progress variable. A similar effort is planned for the QA and QM progress variables.
LAVI: A Location Aware Virtual Infrastructure for VANETs

Without requiring pre-fixed infrastructure, Vehicular Ad Hoc networks (VANETs) allow drivers to exchange information and access variant services in real-time manner. While achieving significant flexibility and convenience, dynamic network topology is also the source of challenges that invalidate most of well-designed protocols. To address this problem, in this paper, we propose a novel scheme called Location Aware Virtual Infrastructure (LAVI). The fundamental rationale of the LAVI scheme is based on an observation: although each individual vehicle will not stay at a location for an extended period of time, statistically there are some vehicles available as long as the density of vehicles is reasonably high. LAVI creates a virtually stable infrastructure layer on top of the dynamic physical topology. Through extensive experimental study, we have verified the effectiveness of our LAVI scheme.
The Overuse of Cesarean Section: Medical, Legal, Research, and Economical Pitfalls

An attempt was made to: (1) estimate the use and overuse of medically indicated and elective Cesarean sections (CS) in countries with reported lower and higher rates of CS; (2) understand the resource-use implications of indicated and elective CS in countries with lower and higher rates of CS. CS rates published in the literature, as well as in the WHO database were considered to provide country-level estimates of CS rates. Unit costs for the inputs identified were derived from a search of literature and databases, as well as from consultation with costing experts. Findings indicate on an unequal global distribution of CS. Medically not indicated and elective CS posses legal–medical, as well as unequivocal economical pitfalls, and appear to command a disproportionate share of global economic resources. Excessive CS could have important negative implications for health equity within and across countries. If all resources used on elective CS could be allocated to countries with undeserved population, the medically indicated procedures could be fully financed, and there would be a surplus of resources with a value of nearly US/$2 billion. Finally, studies have attempted to model the impact of tort reform on primary and repeat CS rates and have shown that modest improvements in the medical–legal climate may result in reductions in CS. It is concluded that both caps on noneconomic damages and reductions in physician malpractice premiums would result in fewer CS.
Control of intragastric pH with omeprazole 20 mg, omeprazole 40 mg and lansoprazole 30 mg

Background: Single daily doses of proton pump inhibitors, omeprazole and lansoprazole provide effective acid suppression and equal healing and symptom relief in patients with GERD. Despite this, controversy exists as to the efficacy of available proton pump inhibitors in the control of gastric acidity. Aim: To assess the efficacy of omeprazole 20 mg vs. lansoprazole 30 mg and omeprazole 40 mg vs. lansoprazole 30 mg in intragastric pH control. Methods: Study I: 12 Helicobacter pylori-negative volunteers (mean age 33 years) were treated with omeprazole 20 mg and lansoprazole 30 mg in random order before breakfast for 7 days. Study II: 24 subjects (mean age 36 years) were similarly treated with omeprazole 40 mg and lansoprazole 30 mg for 7 days after a baseline pH study. One week washout was allowed between studies. Subjects had the same meal on each study day. On day seven, a 24-h intragastric pH study was performed. The percentage time for which gastric pH > 4 was analysed (Gastrosoft, Synectics Medical Inc.) and expressed as mean ± s.d. Results: (1) Omeprazole 20 mg and lansoprazole 30 mg showed no significant difference in the percentage time for which gastric pH > 4 in the daytime and night-time periods. (2) The percentage time for which pH > 4 with omeprazole 40 mg was significantly greater than lansoprazole 30 mg in both daytime (61 ± 19% vs. 48 ± 14%, P 4 in the daytime (69 ± 18% vs. 51 ± 15%, P=0.015) than omeprazole 20 mg. Conclusion: These pH data support the therapeutic equivalency of FDA approved doses of omeprazole and lansoprazole.
H-convex standard fundamental domain of a subgroup of a modular group

The two major ways of obtaining fundamental domains for discrete subgroups of SL(2,ℝ) are the Dirichlet Polygon construction (see Lehner in Discontinuous Groups and Automorphic Functions, American Mathematical Society, Providence, 1964) and Ford’s construction (see Ford in Automorphic Functions, McGraw–Hill, New York, 1929). Each of these two methods yield a hyperbolically convex fundamental domain for any discrete subgroup of SL(2,ℝ).
Extracellular polysaccharide and leaf capacitance in a Hawaiian bog species, Argyroxiphium grayanum (Compositae-Madiinae)

Mature leaves of Argyroxiphium grayanum exhibit an unusual structure-function relationship. The leaves are traversed by several large channels filled with extracellular polysaccharide. Infrared spectral data suggest that the polysaccharide is mainly pectin, which is consistent with previous data based on its histochemical staining properties. The polysaccharide exhibits a very high water-holding capacity, which appears to result in a very high leaf capacitance at high water contents and water potentials. The volume-normalized leaf capacitance of A. grayanum is 0.67 MPa-' over the water potential range of -0.1 to -0.5 MPa. Coupled with the low time constant for water flux within the leaves (57 sec), the high leaf capacitance of A. grayanum may enable it to avoid rapid declines in leaf water potential. Thus, in its native bog habitat in Hawaii, the high leaf capacitance of A. grayanum may be of benefit in terms of minimizing the development of short-term leaf water deficits. SPECIES in the endemic Hawaiian genus Argyroxiphium are characterized by the presence of large amounts of extracellular polysaccharide in their mature leaves (Carlquist, 1957; Carr, 1985; Kim, 1987). The polysaccharide accumulates in channels traversing the length of the leaves. Based on its histochemical staining properties, the polysaccharide appears to
Physical and chemical characterization of coal particles used as entrained flow gasifier feedstock: Heterogeneity in mineral matter distribution

Abstract Several challenges still exist in successful and reliable operation of entrained flow slagging gasifiers (EFG) using coal as a fuel. The formation of flyash and its carryover with the gas stream causes fouling and plugging of syngas coolers, leading to reduction in heat rate and overwhelming of the solids handling systems. In order to predict flyash formation as well as carbon loss in an EFG, a thorough understanding of the effect of feedstock properties on fuel conversion rates during gasification is required. Current state of the art in gasification modeling treats coal as a homogenous material although it well known that coal is heterogeneous. Different classes of particles, when fed into an EFG, behave differently in terms of carbon conversion and mineral transformations. Therefore, it is critical to develop modeling tools that can incorporate physical and chemical characteristics of the feedstock and the effect of the operating conditions on particle transformations, in order to predict fate of the char/ash particles generated in the gasifier. During the grinding of coal, macerals and minerals separate due to mineral liberation. When subjected to gravity fractionation, the liberated minerals tend to accumulate in heavier density particles. Various physical and chemical characterizations are performed on size separated particle classes of the four gravity fractions with an aim to bring out the heterogeneity in the coal and its impact on conversion. Characterization indicated that almost all of the gasifiable matter is present in the two lighter gravity fractions and bulks of the minerals are present in the two heavier gravity fractions. The mineral matter was characterized and quantified using ash yield measurements, X-ray fluorescence, X-ray diffraction, Computer Controlled Scanning Electron Microscopy (CCSEM) and the iron minerals were measured using Mossbauer spectroscopy. Characterization results show the heterogeneity across the coal in multiple chemical components and prompt the need to account for heterogeneity in models.
Magnetic anisotropy in epitaxial metal films

Abstract A pictorial tutorial is presented which illustrates how details of the metal/substrate interface affect the magnetic anisotropy of 3d transition metal films which are epitaxially grown on closely lattice-matched substrates.
Does the teddy bear sign predict psychogenic nonepileptic seizures

This study evaluated whether adults and older teenagers who bring toy stuffed animals to an epilepsy monitoring unit (EMU), i.e., the "teddy bear sign," were more likely to be diagnosed to have psychogenic nonepileptic seizures (PNES) than to have epilepsy. We prospectively evaluated 335 patients, aged 15 years and older, admitted to our EMU over a 19-month period, assessing age at seizure onset, duration of seizures, gender, seizure diagnosis, presence of intellectual disabilities, presence of psychiatric illness, and possession of a toy stuffed animal in the EMU. Among all ages, patients who brought toy stuffed animals were not more likely to have PNES or both PNES and epilepsy than to have epilepsy alone. For those 18 and over, there was a significant difference but only after adjusting for all other patient characteristics, and absolute differences were small. Patients 18 and older with stuffed animals had a 3.21 (95% confidence interval = 1.58, 8.90) times greater odds of being diagnosed to have PNES or both PNES and epilepsy than to have epilepsy alone after adjusting for other patient characteristics (p = 0.022). We conclude that patient possession of toy stuffed animals in the EMU is not a reliable sign of PNES.
A novel indicator series for measuring pKa values in acetonitrile

Abstract A series of substituted azobenzene dyes was found to span a range of 8 p K a units in acetonitrile. The UV absorption spectra of the dyes are responsive to protonation, changing in both absorption maximum and intensity. These characteristics make the dyes useful as indicators for the measurement of p K a values of neutral organic bases that absorb in the visible region of the spectrum.
Renewable Energy Technologies: Panacea for World Energy Security and Climate Change?☆

The rapid increase in anthropogenic greenhouse gas concentrations in the last several decades has caused observable changes in global climate on all continents. Carbon dioxide, the primary causative agent of climate change has increased from long-term mean average of 275 ppm to the current level of 400 ppm. About 85% of the current global energy production and use is based or derived from fossil fuels. If there is no concerted action by the global community, CO2 levels could increase by 130% by mid century resulting in large-scale climate changes such as the disintegration of the West Antarctic ice sheet, large-scale coral reef bleaching, and shutdown of the ocean circulation system. Stabilization of CO2 levels will require a deceleration in the rate of increase in fossil fuel consumption, and the use of emission-free power sources in the immediate future. The former can have immediate ameliorative effects, whereas the latter will require substantial investment in research and development to find and implement innovative technologies. However there are limits to technological solutions to sustainable development. Renewable energy technologies and low-carbon emission technologies will have material and environmental constraints with as yet undetermined consequences. In addition to technological solutions, it is important to develop needed social and political infrastructure to decrease future energy demand by controlling population growth and energy intensity.
Comparative analysis of the interaction between habitat and growth form in diatoms.

We characterized the evolutionary history of growth form (solitary–colonial) and its interaction with species’ habitat (planktonic–benthic) across a multi-gene phylogeny encompassing a broad sample of the order-level diversity of diatoms. We treated these characters broadly, modeling the evolution of aggregation of cells into a colony irrespective of the way aggregation is achieved, and relating the growth form to a broad concept of niche location: in the plankton or benthos. The results showed that habitat shifts are rare implying conservatism in niche location at the level of large clades. On the other hand, the evolutionary history of growth form is more dynamic with evolutionary rates that vary across the tree. Analyses of a possible interaction revealed that shifts in growth form are independent of habitat and that traversing between habitats does not hinge upon species’ growth form. Our findings help to fill a gap in the understanding of diatom niche and growth form macroevolution and contribute toward a platform for the comparative study of the mechanisms underlying diatom species and functional diversity.
Wind-driven sand in Coachella Valley, California: Further data

The last 5 yr (1964–1969) of a 16-yr field experiment involving unidirectional windblown rock and mineral debris focused on study of ground-based objects. A large increase in wind-blown material crossing the plot resulted from accelerated fluvial flooding of the upwind alluvial source area starting in 1964. The plot itself was destroyed by such flooding in early 1969. Maximum cutting of 2.8 cm in 15 yr on a vertical lucite rod occurred on its oblique upwind sides, at 10 to 15 cm above ground. Cutting rate in the last 3 yr was 15 times greater than in the preceding 12 yr, coincident with the increased flux of wind-borne material. A 30-cm gypsum-cement cube showed an 11-fold increase of cutting rate during the last 4 yr (3.6 cm/yr compared to 0.34 cm/yr). Total cutting on the front face was 18 times greater than on the two side faces combined, an average cutting ratio of 36/1. Common red bricks recorded an average front- to side-face cutting ratio of 20/1, and a front-to-top ratio of 45/1. Cutting of 1 to 2 mm occurred on hard crystalline rock within 15 yr, much of it in the last 5 yr. Changes in orientation and position of gympsum-cement cubes and common bricks were produced by basal ground scour, tilting, rotation, creep, and tumbling. Newly placed hydrocal cubes developed upwind tilts as much as 17° in as little as 69 days (d), owing to basal scour. A slow upwind creep of 2 to 3 cm accompanied scour and tilt. A 90° rotation around a near-vertical axis of a brick demonstrated the importance of lever-arm length offered to the wind. Movements of many centimetres and complete reversals, bottom for top, were caused by tumbling. Separation of the base of cubes from the ground by tilting or by perching on residual pebbles, owing to scour or overturn, usually produced an instability favorable to movement.
The effect of low power plasmas on carbon fibre surfaces

Abstract The effect of a variety of low power plasma treatments (e.g., NH3, N2, air and Ar) on low modulus carbon fibre surfaces have been examined using X-ray photoelectron spectroscopy. Grazing angle techniques have been used to probe only the first 12–15A of the fibre surface. Plasma treatments were carried out in an in situ plasma cell which was attached to a PHI 5400 X-ray photoelectron spectrometer. This enabled the immediate effects of the plasma to be studied before the treated surface was exposed to air. Air plasmas introduced both alcohol and carboxyl groups onto the fibre surfaces. Nitrogen plasmas gave very similar results to ammonia plasmas with the formation of three nitrogen containing species on the fibre surface. The signal at 398.9eV was assigned to a combination of aromatic amines (-NH2), and -CNH groups. Its relative intensity, as expected was greater for fibres treated in ammonia plasmas. Air exposure of these activated surfaces results in a strongly bound -O-H layer. Significant etching or pitting was not observed in the scanning electron micrographs of these treated fibres. Comparing XPS spectra of the immediate surface with those taken at bulk sensitive angles, it can be concluded that chemical change only occurred in the first few atomic layers.
Characterization of Autotetraploid Russian Wildrye Produced with Nitrous Oxide

Poor seedling vigor is a major factor limiting widespread use of Russian wildrye [Psathyrostachys juncea (Fischer) Nevski] (2n=2×=14) as complementary pasture. Induced pulyploidy has been shown to increase plant vigor, particularly seedling vigor, of other diploid species. Objectives of this study were to produce autotetraploids in Russian wildrye using the N 2 O technique and to ascertain meiotic stability and seedling vigor of induced autotetraploids
Quantification of radiotracer uptake with a dedicated breast PET imaging system.

Tomographic breast imaging techniques can be used to quantify radiotracer uptake in breast and tumor tissue. However, physical processes common to PETimaging can confound accurate quantification. In this investigation, we assessed the effects of these phenomena and tested correction schemes for our new positron emission mammography–tomography system (PEM–PET). The PEM–PET scanner utilizes two sets of rotating planar detector heads. Each unit consists of a 4 × 3 array of Hamamatsu H8500 flat panel position sensitive photomultipliers coupled to a 96 × 72 array of 2 × 2 × 15 mm 3 LYSO detector elements ( pitch = 2.1 mm ) . Image reconstruction is performed with a 3D-OSEM algorithm parallelized to run on a multiprocessor computer system. The reconstructed field-of-view is 15 × 15 × 15 cm 3 . Much of the testing procedures were based on NEMA-NU2/2001 protocols. Count rate losses due to pulse pile-up, image contamination due to acceptance of random coincidences and Compton scatter, and image artifacts produced by photon attenuation were measured. It was found that the system was susceptible to count rate losses when moderate levels of radiation were present in the scanner due to the current design of the event trigger electronics. Application of corrections for Compton scattering,photon attenuation and dead time resulted in improved estimations of F 18 concentration in simplified phantom studies. Results from these preliminary studies indicate that the PEM–PET scanner will be useful for the quantification of radiotracer uptake in breast tumors, possibly facilitating early assessment of cancer treatments.
A deterministic analysis of oversampled A/D conversion and Sigma Delta modulation

As an alternative to the usual statistical analysis, the authors present a purely deterministic analysis of oversampled A/D (analog-to-digital) conversion and sigma-delta modulation, which requires no assumption on the quantizer error. This leads to the notion of a consistent estimate for the decoding, which is a necessary condition for optimality. Algorithms using convex projections are discussed and the reduction of decoding error from SiO(R/sup -(2n+1)/)to SiO(SiR/sup -(2n+2)/) (where R is the oversampling ratio and n is the order of the encoder) is demonstrated experimentally for multiloop and multistage sigma-delta modulators. >
Pharmacologically induced hypothermia attenuates traumatic brain injury in neonatal rats

Neonatal brain trauma is linked to higher risks of mortality and neurological disability. The use of mild to moderate hypothermia has shown promising potential against brain injuries induced by stroke and traumatic brain injury (TBI) in various experimental models and in clinical trials. Conventional methods of physical cooling, however, are difficult to use in acute treatments and in induction of regulated hypothermia. In addition, general anesthesia is usually required to mitigate the negative effects of shivering during physical cooling. Our recent investigations demonstrate the potential therapeutic benefits of pharmacologically induced hypothermia (PIH) using the neurotensin receptor (NTR) agonist HPI201 (formerly known as ABS201) in stroke and TBI models of adult rodents. The present investigation explored the brain protective effects of HPI201 in a P14 rat pediatric model of TBI induced by controlled cortical impact. When administered via intraperitoneal (i.p.) injection, HPI201 induced dose-dependent reduction of body and brain temperature. A 6-h hypothermic treatment, providing an overall 2-3°C reduction of brain and body temperature, showed significant effect of attenuating the contusion volume versus TBI controls. Attenuation occurs whether hypothermia is initiated 15min or 2h after TBI. No shivering response was seen in HPI201-treated animals. HPI201 treatment also reduced TUNEL-positive and TUNEL/NeuN-colabeled cells in the contusion area and peri-injury regions. TBI-induced blood-brain barrier damage was attenuated by HPI201 treatment, evaluated using the Evans Blue assay. HPI201 significantly decreased MMP-9 levels and caspase-3 activation, both of which are pro-apototic, while it increased anti-apoptotic Bcl-2 gene expression in the peri-contusion region. In addition, HPI201 prevented the up-regulation of pro-inflammatory tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and IL-6. In sensorimotor activity assessments, rats in the HPI201 treated group exhibited improved functional recovery after TBI versus controls. These data support that PIH therapy using our NTR agonist is effective in reducing neuronal and BBB damage, attenuating inflammatory response and detrimental cellular signaling, and promoting functional recovery after TBI in the developing brain, supporting its potential for further evaluation towards clinical development.
Differential selection for vegetative structure between juvenile brown shrimp ( Penaeus aztecus) and white shrimp ( P. setiferus), and implications in predator-prey relationships

Abstract The distributions of juvenile brown shrimp, Penaeus aztecus, and white shrimp, P. setiferus, (57–72 mm TL) were monitored in partially vegetated laboratory enclosures to examine selection for vegetative structure. Simulated Spartina culms, composed of green straws, were used as structure in the experiments. Brown shrimp selected for this structure during the day but not at night. White shrimp showed no strong selective preference for structure during the day or night. Selection in the field was measured by examining densities of the two species of shrimp (40–80 mm TL) in a Galveston Bay, Texas, salt marsh. Brown shrimp were more abundant in vegetated habitats (Spartina alterniflora) than in adjacent non-vegetated areas. Differences in white shrimp densities between the two habitats were variable, and no consistent pattern was observed. laboratory predation experiments were conducted in non-vegetated and vegetated cages using Atlantic croaker (Micropogonias undulatus) as predators. In non-vegetated cages there was no significant selection for either species of shrimp by the fish. In partially and completely vegetated cages, fish selected white shrimp over brown shrimp. These data suggest that the presence of vegetation alters prey selection by Atlantic croaker, and this interaction may result in greater mortality of white shrimp compared with brown shrimp in salt marshes.
EFFECTS OF SUCCESSIONAL DYNAMICS ON METAPOPULATION PERSISTENCE

The classical (Levins) metapopulation scenario envisions a species persisting in a network of habitat patches through a balance between frequent local (within-patch) extinctions and recolonizations. Although this is the dominant paradigm for species in fragmented habitats, empirical support is limited, and it has been argued that very restrictive conditions on migration rates are required: high enough for recolonization to balance extinctions, but low enough that local populations do not fluctuate in synchrony. Through simulation and analysis of a stochastic spatial model, we argue that the likelihood of persistence via the classical scenario is strongly affected by some basic properties of within-patch successional dynamics whose importance has not been emphasized in metapopulation theory: the distribution of successional stage durations, and whether patches are “refractory” vs. immediately available for recolonization after an extinction has occurred. These properties are tied to the biological causes o...
A 15-month-old child with recurrent otitis media.

DR REYNOLDS: Sam is a 15-month-old child who has recurrent otitis media. He lives near Boston with his mother, father, and a healthy older brother, aged 2 years 9 months. Sam is cared for at home while his parents are at work. Born at term in October 2000 by elective repeat cesarean delivery to a healthy 37-year-old gravida 2, para 2 mother after an uncomplicated pregnancy, Sam had a normal hearing screen at birth. At the age of 5 months he had his first episode of acute otitis media, manifested by spontaneous perforation and draining of pus from the left ear. He was treated with amoxicillin, 80 mg/kg per day, and his eardrum was found intact at a subsequent visit. In May, June (twice), August, September, and November of 2001, Sam had 6 more episodes of acute otitis without perforation. His pediatrician, Dr T, noted that the diagnoses were made based on pneumatic otoscopy showing pus behind an immobile tympanic membrane when the patient was symptomatic with cold symptoms, irritability, and/or fever. Sam was treated with amoxicillin, azithromycin, and amoxicillin-clavulanate. Revisits showed a normal tympanic membrane between each episode. In early December 2001, Dr T discussed the relative merits and risks of watchful waiting, prophylactic antibiotics, and tympanostomy tube placement with Sam’s parents. At the time of the interview, Mrs G, Sam’s mother, reported that he had been taking prophylactic amoxicillin, 250 mg/d, for 1 month and had not had another acute otitis media episode. Sam’s past medical history is significant for a buckle fracture of his right radius and ulna. He has had normal growth and has achieved appropriate developmental milestones. His immunizations are up to date, including pneumococcal conjugate vaccine. His only medication is amoxicillin; he has no known drug allergies. He is not exposed to cigarette smoke. Family history is significant for first cousins on his paternal side with recurrent otitis media. Physical examination showed a healthy 15-month-old boy. His weight was 22 lb 14 oz (25th percentile), length 31.5 in (50th percentile), and head circumference 19.75 in (95th percentile). His ear examination results were normal by pneumatic otoscopy bilaterally. Sam has not had a hearing test since birth. His IgG level was borderline low when tested in September 2001 at 288 mg/dL (normal for age, 300-1500 mg/dL); his IgA level was also at the lower limit of normal. His parents are frustrated by his recurrent ear infections and hope that the prophylactic antibiotics prevent future infections.
Magnetic Resonance Imaging of Spiral Vein Graft Bypass of Superior Vena Cava in Fibrosing Mediastinitis

Magnetic resonance imaging (MRI) was used for postoperative evaluation of spiral vein grafts in three patients with fibrosing mediastinitis who had undergone bypass of the superior vena cava (SVC) for SVC syndrome. The MRI images, obtained without ECC triggering, were compared retrospectively with postoperative bilateral arm venograms. Patent grafts were identified by MRI in all patients. Significant stenoses at innominate vein-spiral vein graft anastomoses in two patients were better demonstrated by venography than by MRI. MRI shows promise as a noninvasive technique for postoperative evaluation of spiral vein bypass grafts.
Planetary Nebulae and Halo Dynamics in Early Type Galaxies

The study of extragalactic planetary nebulae has made rapid progress in recent years with the help of high quantum efficiency detectors. A brief but distinctive phase in the late stage of stellar evolution, planetary nebulae (PNe) are not only interesting objects in their own right, but also are extremely valuable and unique tools for probing the host galaxies. Recent studies have used planetary nebulae as test particles to investigate the dynamics and mass distributions in the halos of early type galaxies.
Degradation of type IV collagen by neoplastic human skin fibroblasts

An assay for the degradation of type IV (basement membrane) collagen was developed as a biochemical marker for neoplastic cells from chemically transformed human skin fibroblasts. Type IV collagen was isolated from basement membrane of Syrian hamster lung and type I collagen was isolated from rat tails; the collagens were radioactively labelled by reductive alkylation. The abilities of normal (KD) and chemically transformed (Hut-11A) human skin fibroblasts to degrade the collagens were studied. A cell-associated assay was performed by growing either normal or transformed cells in the presence of radioactively labelled type IV collagen and measuring the released soluble peptides in the medium. This assay also demonstrated that KD cells failed to synthesize an activity capable of degrading type IV collagen whereas Hut-11A cells degraded type IV collagen in a linear manner for up to 4 h. Human serum at very low concentrations, EDTA and L-cysteine inhibited the enzyme activity, whereas protease inhibitors like phenylmethyl sulfonyl fluoride, N-ethyl maleimide or soybean trypsin inhibitor did not inhibit the enzyme from Hut-11A cells. These results suggest that the ability to degrade specifically type IV collagen may be an important marker for neoplastic human fibroblasts and supports a role for this collagenase inmore » tumor cell invasion.« less
PCB Concentrations of Lake Michigan Invertebrates: Reconstruction Based on PCB Concentrations of Alewives (Alosa pseudoharengus) and their Bioenergetics

Invertebrate PCB concentrations are a poorly quantified but crucial step in the trophic transfer of organochlorine contaminants to fishes. In fact, current attempts to quantify PCB fluxes in the Lake Michigan pelagic food web are hampered by poor knowledge of invertebrate PCB concentrations. Models exist that estimate PCB concentrations in fish based upon PCB concentrations in their food. We have used a complementary approach and estimated invertebrate PCB concentrations based upon historical records of alewife PCB concentrations in Lake Michigan. We first developed a model of total PCB accumulation in alewife (Alosa pseudoharengus) using a bioenergetics-based approach to growth. The PCB assimilation efficiency between invertebrate prey and alewife predators was estimated to be about 0.40. We then used the model to hindcast PCB concentrations in the invertebrates that comprised alewife prey. We estimated that median PCB concentrations of Lake Michigan invertebrates have dropped roughly 10-fold from 1976 to 1990; for example, the estimated Diporeia hoyi PCB concentration has dropped from ca. 0.48 mgkg-1 wet weight to 0.04 mgkg-1 wet weight over this time period. The biomagnification ratio (alewife PCB/zooplankton PCB) is about 16-fold (Diporeia hoyi) to 40-fold (copepods/cladocerans). The PCB concentrations in Lake Michigan invertebrates and alewife that we have estimated for 1993 and 1994 should be viewed as predictions, testable as data become available. Because historic data on invertebrate PCB concentrations in Lake Michigan are exceedingly scarce, our estimates should be useful for studies that attempt to quantify the Lake Michigan PCB fluxes or future modeling efforts that attempt to incorporate multiple levels of the Lake Michigan food web.
Permanently implanted recording electrodes for immature animals

Abstract A simple procedure for the implantation of permanent cortical electrodes in immature animals allowing for longitudinal studies of developing bioelectric phenomenon has been described.
Category concept generation in aphasia: The influence of context

Abstract The influence of context on the generation of category concepts for ad hoc and common categories was examined in adults with fluent and nonfluent aphasia and nonbrain-damaged controls. Common categories are natural object concepts, such as ‘furniture’. Ad hoc categories are those that are constructed for use in specialized contexts and are considered instrumental in achieving goals. An example of an ad hoc category is ‘things not to eat on a diet’. Both types of categories have a graded structure which indicates that all members of a category are not equally representative of the category, with some members being better examples than others. Subjects performed a category concept generation task in which they were required to generate category labels for groups of category exemplars presented in isolation or preceded by a contextual vignette. Both groups with aphasia were able to utilize context as effectively as nonbrain-damaged subjects to prime category labels for the ad hoc categories. There w...
Low concentrations of vaginal fetal fibronectin as a predictor of deliveries occurring after 41 weeks

OBJECTIVE: This study sought to determine whether low concentrations of fetal fibronectin in the cervical and vaginal secretions of patients at 39 weeks' gestation predicted pregnancies progressing beyond 41 weeks' gestation. STUDY DESIGN: A retrospective cohort study was undertaken using cervical and vaginal samples collected from 75 consenting patients during the thirty-ninth week of gestation. Levels of fetal fibronectin were measured by immunoassay. Demographic, obstetric, neonatal, and laboratory data were analyzed by Fisher's exact test, Student t test or Wilcoxon's rank-sum test, multiple logistic regression, and receiver-operating characteristic curve analysis. RESULTS: There was a 35.5-fold increase in vaginal fetal fibronectin concentrations among patients delivered at CONCLUSIONS: A vaginal fetal fibronectin value ≥ 60 ng/ml at 39 weeks' gestation is predictive of delivery within 10 days, whereas values
Blood pressure and calcium balance in the Wistar-Kyoto rat.

Recent investigations in human and experimental hypertension have characterized previously unrecognized abnormalities of calcium homeostasis. Data from human and animal studies have indicated that adequate dietary calcium intake may be an important determinant for the development of high blood pressure. Since dietary calcium supplementation has been shown to attenuate the hypertension of the spontaneously hypertensive rat (SHR), the present study was undertaken to assess the effect of dietary calcium intake on the blood pressure of the Wistar-Kyoto rat (WKY), the normotensive genetic control for the SHR. One of three levels of dietary calcium was fed to 36 WKYs beginning at eight to 10 weeks of age (WOA) through 34 WOA. Throughout the period of observation, the WKYs stratified inversely with their level os dietary calcium (p less than .001), i.e. rats fed the lowest level of calcium had the highest blood pressure. WKYs on the high calcium diet experienced an attenuation of their blood pressure with increasing age and dietary calcium intake. These salutary blood pressure effects of dietary calcium were independent of growth and urinary sodium excretion of the rats. Serum ionized calcium (Ca++) increased in the high calcium diet WKYs and appeared to be associated with the blood pressure reduction. The results suggest that calcium intake must be assessed in experimental models of hypertension and that the state of calcium balance is a possibly important determinant of blood pressure regulation.