cssi/SciSciGPT-SciSciNet huggingface dataset:
Surface structure of catalytically-active ceria nanoparticles

Abstract Catalytic mechanisms, and therefore activity, depend on the structure of catalyst surfaces. In turn, surfaces may reconstruct and/or exhibit local configurations that vary from bulk composition and structure. CeO2 (ceria) is a redox catalyst of interest in numerous automotive, energy and, increasingly, biomedical applications. Previous studies aimed at understanding catalytic mechanisms on ceria have limited consideration to systems with bulk-like stoichiometric or sub-stoichiometric surfaces. Here we summarize previous computational studies on ceria surfaces, nanoclusters, and nanoparticles, and highlight challenges in constructing physically-representative ceria nanoparticle (CNP) structures. Setting aside assumptions of bulk-like stoichiometric or sub-stoichiometric ceria surface terminations, we report results of DFT + U calculations and show that sufficiently small CNPs are not bulk-terminated, but rather are stabilized by the formation of Oxq groups (−2 ⩽ q ⩽ 0, x ⩽ 3) at corners, edges, and {1 0 0} facets. These surface structures, not the annihilation and regeneration of O-vacancies, may directly control reduction/oxidation catalysis at CNPs below a critical size. As anion groups other than Oxq groups could be incorporated in stable CNP surfaces, this suggests the possibility of tailoring small CNP structures and mechanisms for particular catalytic reactions.
The development of a method to measure head acceleration and motion in high-impact crashes.

OBJECTIVE: To establish a mechanism to obtain precise measurements of the accelerations of the head in the high-speed racing environment and during crash impacts. The long-term goal is to apply this system to the assessment of head injury in automobile racing drivers and then in participants in other helmeted sports. METHODS: A multidisciplinary team conceptualized, designed, and successfully tested a triaxial accelerometer system capable of measuring head acceleration and motion in high-impact crashes. The system has been implemented successfully in the professional racing environment. RESULTS: Accurate and reproducible data have been obtained from the accelerometer system in tests on manikins and cadavers and in actual racing events. The system has been implemented in two professional racing series in 2003. Information gained from the accelerometer system is currently being entered into a database. Eventually, the data should aid in the development of improved cockpit head protection in racing cars. Improved helmet design not only in motor sports but also in other helmeted sports should benefit from the data collected. These data will also aid the development of improved head injury protection in military aircraft and passenger vehicles. CONCLUSION: Although there has been a significant decrease in the overall rate of injury during the past 25 years, head injury remains a serious safety concern in motor sports and the greatest cause of death. Sports-related head injuries are also of great concern because repeated mild head injury has become an important health issue with potential long-term disability. True human tolerance to brain injury has yet to be established. Our scientific knowledge of brain injury is currently based on results derived from manikin, cadaver, and human volunteer testing, along with animal and computer models. The racing environment represents a venue to ethically measure and evaluate the forces involved in human brain injury.
Reducing Diabetes in Indian Country: Lessons from the Three Domains Influencing Pima Diabetes

The prevalence of diabetes among Pima (Akimel O’odham) Indians involves three important domains: political-economic, genetic, and cultural. Programs in diabetes education have made noteworthy improvements in the last two decades in addressing cultural information and attitudes. It is less common to see political-economic factors addressed, particularly the structural barriers to care that include poverty and unemployment. The genetic contributions to modern rates of diabetes have, perhaps, been overemphasized in the past, contributing to a sense that this disease is inevitable in American Indian populations. I review six lessons drawn from these domains and from diabetes prevention and treatment programs in Indian country: 1) the basic importance of cultural sensitivity; 2) the strengths of community participation; 3) the influential but not dominant significance of genetics; 4) some relevant structural changes in forms of health care; 5) the need for political-economic change within tribes to sustain com...
Excess silica in omphacite and the formation of free silica in eclogite

Silica lamellae in eclogitic clinopyroxene are widely interpreted as evidence of exsolution during decompression of eclogite. However, mechanisms other than exsolution might produce free silica, and the possible mechanisms depend in part on the nature and definition of excess silica. ‘Excess’ silica may occur in both stoichiometric and non-stoichiometric pyroxene. Although the issue has been debated, we show that all common definitions of excess silica in non-stoichiometric clinopyroxene are internally consistent, interchangeable, and therefore equivalent. The excess silica content of pyroxene is easily illustrated in a three-component, condensed composition space and may be plotted directly from a structural formula unit or recalculated end-members. In order to evaluate possible mechanisms for the formation of free silica in eclogite, we examined the net-transfer reactions in model eclogites using a Thompson reaction space. We show that there are at least three broad classes of reactions that release free silica in eclogite: (i) vacancy consumption in non-stoichiometric pyroxene; (ii) dissolution of Ti-phases in pyroxene or garnet; (iii) reactions between accessory phases and either pyroxene or garnet. We suggest that reliable interpretation of the significance of silica lamellae in natural clinopyroxene will require the evaluation not only of silica solubility, but also of titanium solubility, and the possible roles of accessory phases and inclusions on the balance of free silica.
Regulatable Acetylcholine-Producing Fibroblasts Enhance Cognitive Performance

Regulatable gene therapy systems provide a method to alter neurotransmitter levels in vivo. We developed a rodent fibroblast cell line expressing the choline acetyltransferase (ChAT) cDNA that is silenced by doxycycline (DOX) administration. The ability of the cell line to improve cognition was tested by grafting after cholinergic lesions. Ibotenic acid was injected bilaterally into the nucleus basalis of rats, which were distributed into three groups. One group received no treatment, while the second group received cortical transplants (Graft). The third group received identical grafts but was treated with DOX to turn off ChAT expression (Graft/DOX). An unlesioned group served as control. Water maze acquisition was significantly better in the Graft group compared to the Graft/DOX group, an effect also seen in the retention and spatial probe trials. However, cognitive enhancement was restricted to spatial tasks, as inhibitory avoidance or open-field activity measures were unchanged. Molecular and biochemical analyses confirmed that DOX regulated transgene transcription and ACh levels. This study demonstrates that regulatable gene therapy has therapeutic value for single-gene disorders and also provides a mechanism to deliver small molecules in a spatiotemporal pattern to delineate the role of these compounds in discrete behavioral tasks.
Coherence between low‐level cloud motion vectors and surface wind measurements Near 0°, 152°W from April 1979 to February 1980

Abstract Low‐level cloud motion vectors determined by the National Oceanic and Atmospheric Administration (NOAA) and the University of Wisconsin in a 5‐degree square centred at 0°, 152°30’ W were intercompared with moored buoy wind measurements made at 0°, 152°W during April 1979‐February 1980. At the site of the intercomparison test the prevailing wind direction was easterly; monthly mean values of the meridional wind speed were less than 20% of the zonal component. The surface winds measured during the observational period were similar to the climatological‐mean wind conditions. Although the satellite wind speeds were larger than buoy wind speeds, as a priori expected, because of the vertical separation between the measurements, the comparison indicated that in the case of the zonal component there was a maximum usable frequency (muf) below which cloud drifts and surface wind vectors were 95% significantly correlated and the correlation was greater than the 50% noise level. The muf were 0.17 and 0.3 cpd...
A noble conception

Science can explain many things in the natural world. Although the laws of gravity, the origin of galaxies and the Universe are commonly accepted, the theory of evolution is still questioned by some. There are clear reasons for why that is, and why it need not be so.
A NMR study of mobility in the histone octamer

The histone octamer from chicken erythrocytes was studied in 2 M NaCI using 500 mHz 1H NMR spectroscopy. We compared the spectrum of control octamers with that of octamers isolated from trypsinized nucleosome core particles. We observe that the sharp resonances found in the spectrum of the native octamer disappear completely after trypsinization. Therefore, within the time frame of the NMR experiment, all of the mobile amino acid residues in the histone octamer are found in the well defined trypsin sensitive domains. These results indicate that there is a very clear structural demarcation between the random coil N- and C-terminal tails and the globular domains of the histones.
Effect of prostaglandin E in multiple experimental models. IV. Effect on resistance to endotoxin and tumor necrosis factor shock.

Abstract Administration of a long-acting prostaglandin E, 16,16-dimethyl-PGE (dPGE), to rats improves their survival of bacterial peritonitis. We examined the mechanism of this protective effect with reference to its interaction with the release of cachectin (TNF). Sixty rats received saline, 20 μg/kg dPGE, or 80 μg/kg dPGE 12 hr prior to endotoxin and continuing for 48 hr. Survival rates for the saline, 20 μg/kg dPGE, and 80 μg/kg dPGE groups were 0, 40, and 85%, respectively. Forty rats received saline or 80 μg/kg dPGE, with the initial dose being 3 hr following endotoxin challenge and continuing for 48 hr. Survival rates for both groups were 0%. Sixty rats received saline or 80 μg/kg dPGE at 12 and 1 hr prior to endotoxin. Two hours after challenge, they were sacrificed and plasma TNF levels were assayed. The plasma TNF level in saline-treated rats was 22.72 ± 0.83 ng/ml and in the dPGE-treated group, 16.03 ± 1.13 ng/ml (P
Small-molecule inhibitors of the AAA+ ATPase motor cytoplasmic dynein

The conversion of chemical energy into mechanical force by AAA+ (ATPases associated with diverse cellular activities) ATPases is integral to cellular processes, including DNA replication, protein unfolding, cargo transport and membrane fusion. The AAA+ ATPase motor cytoplasmic dynein regulates ciliary trafficking, mitotic spindle formation and organelle transport, and dissecting its precise functions has been challenging because of its rapid timescale of action and the lack of cell-permeable, chemical modulators. Here we describe the discovery of ciliobrevins, the first specific small-molecule antagonists of cytoplasmic dynein. Ciliobrevins perturb protein trafficking within the primary cilium, leading to their malformation and Hedgehog signalling blockade. Ciliobrevins also prevent spindle pole focusing, kinetochore-microtubule attachment, melanosome aggregation and peroxisome motility in cultured cells. We further demonstrate the ability of ciliobrevins to block dynein-dependent microtubule gliding and ATPase activity in vitro. Ciliobrevins therefore will be useful reagents for studying cellular processes that require this microtubule motor and may guide the development of additional AAA+ ATPase superfamily inhibitors.
Amyotrophic Lateral Sclerosis Association

ABSTRACT Amyotrophic lateral sclerosis (ALS), most commonly known as Lou Gehrig's disease, is a progressive neurodegenerative disease that attacks nerve cells in the brain and spinal cord resulting in muscle weakness and atrophy. The ALS Association's national Web site provides comprehensive information on a wide variety of topics pertinent to ALS patients, caregivers, family members, and health care professionals. This well-organized, easy-to-navigate site is an excellent resource for anyone seeking to learn about ALS.
A Review of “The Anatomy and Systematics of Eustreptospondylus Oxoniensis, a Theropod Dinosaur From the Middle Jurassic Of Oxfordshire, England”, by R. Sadleir, P. M. Barrett, and H. P. Powell, 2008. Monograph of the Palaeontographical Society, London, 82 pp., 20 Pl., £110.00, ISSN 0269-3445.

There was a time, some time ago now, when theropod dinosaur remains were habitually referred to the genus Megalosaurus, initially based on specimens from the Middle Jurassic of Oxfordshire. Those t...
Regional visibility modeling for the Eastern United States

Abstract Visibility modeling over long transport distances is complicated not only by the chemical and removal processes, but also by the multiplicity of sources from different areas that contribute to the particle and gaseous concentrations—and visibility impairment—at specific locations. To study interregional pollutant exchanges and their effect on visibility, a regional model has been developed and applied to the eastern United States and the visibility reduction budgeted according to area of origin. The new model, called VISMAP-1, produces short-term (three-hour) and long-term (monthly) sulfate concentrations; visibility calculations are made by applying a mass-to-light-scattering function to the aerosol concentrations. This function is weighted according to relative humidity to account for hygroscopic particle growth. One of the most useful features of this model is its capability to budget fine-particulate and gaseous concentrations in various receptor regions according to the contribution of source regions. In this analysis for visibility effects, three-hour SURE (Sulfate Regional Experiment) sulfate measurements for July 1978 are compared to fine-particle calculations to evaluate the model's ability to predict the transport of aerosol sulfur for the shorter averaging period. Visibility is modeled from the sulfate calculations using an empirical mass-to-light-scattering function. This technique is commonly used to determine aerosol light-scattering properties at given relative humidities. National Weather Service visual range observations have been compared with the model's visibility calculations; both regional patterns of visibility degradation and the absolute magnitude of the reduction in visual range are evaluated. Preliminary results are encouraging and the VISMAP modeling approach appears to be a useful step toward identifying long-range source/receptor relationships that affect visibility.
Comment on “The Cure and Feeding of Windigos: A Critique”

Brown (1971) has presented a paper regarding Rohrl's (1970) "major new point" and "intriguing hypothesis" regarding a nutritional factor in windigo psychosis. I maintain here that: (1) I have not set forth, to my knowledge, the "hypothesis" attributed to me; (2) the idea of a possible nutritional factor is well known and not new; and (3) as a result of overstatement and other factors demonstrated in Brown's (1971) paper, the "critique," in many ways, does not apply to the present work. I welcome the opportunity to restate my thesis here, that, in order properly to assess the nature of windigo psychosis, we should view it as a multifactorial phenomenon. Teicher (1960), in his ample discussion of seventy windigo cases, demonstrates that, in addition to the cultural factors involved, there is also a wide variety of circumstances, some of which will be reviewed below. Fogelson (1965), following Hallowell (1934), has attempted to divide aspects of windigo psychosis into a threefold descriptive model: the phases include "Normality," "Psychosis," and "Treatment," as well as "Innovated Personality." The "Treatment" phase, in those rare cases that are more completely documented and described, appears to include, both in folk belief and in actuality, a nutritional element. The Rev. J. M. Cooper (1933), also a university faculty member, was among the first to propound the probability of a "winter famine" preponderance of windigo cases. His fieldwork as well as his literary research led him to discover a long-standing belief among Cree, Waswanipi, Nipigon, and other groups that "a human Witiko has a piece of ice inside him. To cure him, give him a bit of grease, which will melt this ice" (Ibid.:22). Nowhere does a primary source description include the witnessing of actual vomiting. Wherever vomiting is, indeed, reported, it is of ice; and, in some instances, even this sort of regurgitation is not apparently present at all. Therefore, and for reasons to be added below, I tend to disagree with the literalistic surmise that the ingestion "emphasizes disgorgement rather than feeding" (Brown 1971:20). The question whether the victims vomited or whether the
Neurocognitive outcomes in long-term survivors of childhood acute lymphoblastic leukemia treated on contemporary treatment protocols: A systematic review

Abstract The intensified administration of chemotherapeutic drugs has gradually replaced cranial radiation therapy (CRT) for the treatment of childhood acute lymphoblastic leukemia (ALL). While CRT is often implicated in neurocognitive impairment in ALL survivors, there is a paucity of the literature that evaluates the persistence of neurocognitive deficits in long-term survivors of pediatric ALL who were treated with contemporary chemotherapy-only protocols. Results from this systematic review concurred to the probable cognitive-sparing effect of chemotherapy-based protocols over CRT in long-term survivors. However, coupled with multiple intrinsic and extrinsic factors, survivors who received chemotherapy treatment still suffered from apparent cognitive impairment, particularly in the attention and executive function domains. Notably, there is evidence to suggest that the late neurotoxic effect of methotrexate on survivors’ neurocognitive performance may be dose-related. This review also recommends future pharmacokinetic, neuroimaging and genetic studies to illuminate the multifactorial nature of this subject matter and discusses the potential value of neurochemical, physiological, inflammatory and genetic markers for the prediction of susceptibility to neurocognitive impairment in long-term survivors of childhood ALL.
Dynamics of Surface Catalyzed Reactions; the Roles of Surface Defects, Surface Diffusion, and Hot Electrons†

The mechanism that controls bond breaking at transition metal surfaces has been studied with sum frequency generation (SFG), scanning tunneling microscopy (STM), and catalytic nanodiodes operating under the highpressure conditions. The combination of these techniques permits us to understand the role of surface defects, surface diffusion, and hot electrons in dynamics of surface catalyzed reactions. Sum frequency generation vibrational spectroscopy and kinetic measurements were performed under 1.5 Torr of cyclohexene hydrogenation/dehydrogenation in the presence and absence of H2 and over the temperature range 300-500 K on the Pt(100) and Pt(111) surfaces. The structure specificity of the Pt(100) and Pt(111) surfaces is exhibited by the surface species present during reaction. On Pt(100), ﷿-allyl c-C6H9, cyclohexyl (C6H11), and 1,4cyclohexadiene are identified adsorbates, while on the Pt(111) surface, ﷿-allyl c-C6H9, 1,4-cyclohexadiene, and 1,3-cyclohexadiene are present. A scanning tunneling microscope that can be operated at high pressures and temperatures was used to study the Pt(111) surface during the catalytic hydrogenation/dehydrogenation of cyclohexene and its poisoning with CO. It was found that catalytically active surfaces were always disordered, while ordered surface were always catalytically deactivated. Only in the case of the CO poisoning at 350 K was a surface with a mobile adsorbed monolayer not catalytically active. From these results, a CO-dominated mobile overlayer that prevents reactant adsorption was proposed. By using the catalytic nanodiode, we detected the continuous flow of hot electron currents that is induced by the exothermic catalytic reaction. During the platinum-catalyzed oxidation of carbon monoxide, we monitored the flow of hot electrons over several hours using a metal-semiconductor Schottky diode composed of Pt and TiO2. The thickness of the Pt film used as the catalyst was 5 nm, less than the electron mean free path, resulting in the ballistic transport of hot electrons through the metal. The electron flow was detected as a chemicurrent if the excess electron kinetic energy generated by the exothermic reaction was larger than the effective Schottky barrier formed at the metalsemiconductor interface. The measurement of continuous chemicurrent indicated that chemical energy of exothermic catalytic reaction was directly converted into hot electron flux in the catalytic nanodiode. We found the chemicurrent was well-correlated with the turnover rate of CO oxidation separately measured by gas chromatography.
Blazing New Paths for Inter disciplinary Hydrology

As society tackles climate change adaptation and planning, community and regional managers are turning to science for answers. The role of water, and thus hydrologists, is central to many pressing questions. Faced with concerns about water resource availability and quality degradation, society needs information on hydrologic processes at the catchment scale and smaller; although the community has significantly improved its understanding of such processes, there is a need for a new and integrative foundation of knowledge. Hydrology must not only reach beyond disciplinary boundaries but also forge broad connections with natural and social sciences to make useful water cycle predictions at regional and global scales.
Injection of Electrons into He II from an Immersed Tungsten Filament

Tungsten filaments have been operated while immersed in He II at temperatures up to 2500\ifmmode^\circ\else\textdegree\fi{}K, and electron currents as high as 0.5 \ensuremath{\mu}A have been produced in the superfluid, yielding densities of at least ${10}^{9}$ negative ions/${\mathrm{cm}}^{3}$. The fluid in the vicinity of the filament remains quiescent under these conditions as a result of a stable vapor film which forms around the filament.
Understanding Neutral Genomic Molecular Clocks

The molecular clock hypothesis is a central concept in molecular evolution and has inspired much research into why evolutionary rates vary between and within genomes. In the age of modern comparative genomics, understanding the neutral genomic molecular clock occupies a critical place. It has been demonstrated that molecular clocks run differently between closely related species, and generation time is an important determinant of lineage specific molecular clocks. Moreover, it has been repeatedly shown that regional molecular clocks vary even within a genome, which should be taken into account when measuring evolutionary constraint of specific genomic regions. With the availability of a large amount of genomic sequence data, new insights into the patterns and causes of variation in molecular clocks are emerging. In particular, factors such as nucleotide composition, molecular origins of mutations, weak selection and recombination rates are important determinants of neutral genomic molecular clocks.
Terrorism cuts across the East and the West: Deconstructing Lewis's Orientalism

(2003). Terrorism cuts across the East and the West: Deconstructing Lewis's Orientalism. Third World Quarterly: Vol. 24, No. 1, pp. 177-186.
APPLICATION OF MANY-BODY GREEN'S FUNCTIONS TO THE SCATTERING AND BOUND- STATE PROPERTIES OF HELIUM.

The approximation scheme suggested by Schneider, Taylor, and Yaris is applied to the scattering and the bound-state properties of the helium atom. Elastic scattering phase shifts for $s$, $p$, and $d$ partial waves, ionization potentials, one-electron ground-state properties (i.e., electron densities, the natural orbitals, and the ground-state energy), and excitation energies from the ground to the excited states of helium have been calculated simultaneously from the linear-response function and one-particle Green's function. This simultaneity is made possible by concentrating all computational effort on calculating the one- and two- particle amplitudes rather than on the ground- and excited-state wave functions. These amplitudes can be directly related to almost all the properties of physical interest in atomic and molecular systems. Our results for both the scattering- and stationary-state properties are in good agreement with experiment and other previous calculations.
On the relationship between the binding of ribosomal protein S1 to the 30 S subunit of Escherichia coli and 3′ terminus of 16 S RNA☆

Abstract 30 S ribosomal subunits in many preparations have two binding sites for S1 (Laughrea & Moore, 1977). These two binding sites can be readily distinguished on the basis of their affinity for S1. Reactivation procedures (Zamir et al. , 1971) selectively modify the interaction of the 30 S subunit with S1: the weaker binding site disappears but the affinity of the stronger stays unchanged. Experiments performed to identify molecular components of S1's binding site(s) on the 30 S subunit have produced the following results. 1. (1) The 50 nucleotides at the 3′ end of 16 S RNA are not required for high affinity binding of S1 to 30 S subunits, but appear involved in binding S1 to the second, weaker, binding site. 2. (2) A 2.7 to 3.3 m -ammonium chloride washing of 30 S subunits inactivates them for high affinity S1 binding, but not for low affinity binding. It is possible that two or more ribosomal proteins among the group. S2, S9, S10 and S14 are involved in high affinity S1 binding. 3. (3) N -ethylmaleimide-labeled S1, which loses its “RNA helix-unwinding” capacity (Kolb et al. , 1977), is not significantly altered in its capability for binding to either the high affinity or the low affinity binding site, implying that S1 has at least two active sites, one by which it binds to the 30 S subunit and a second, which is N -ethylmaleimide-sensitive, through which it exerts its function.
Thermolytic conversion of a bis(alkoxy)tris(siloxy)tantalum(V) single-source molecular precursor to catalytic tantala-silica materials

The new complex ({sup i}PrO){sub 2}Ta[OSi(O{sup t}Bu){sub 3}]{sub 3} (1) was prepared via silanolysis of Ta(O{sup i}Pr){sub 5} with ({sup t}BuO){sub 3}SiOH and is a useful structural and spectroscopic (NMR, FTIR) model of Ta(V) on silica. The complex was also used to prepare tantalum-containing silica materials, via the thermolytic molecular precursor method (yielding Ta{sub 2}O{sub 5}{center_dot}6SiO{sub 2} and Ta{sub 2}O{sub 5}{center_dot}18SiO{sub 2}) or by grafting 1 onto mesoporous SBA-15 silica (yielding a surface-supported tantala species, TaSBA-15). The solution phase thermolysis of 1 in nonpolar media afforded homogeneous, high-surface-area (ca. 450 m{sup 2} g{sup -1}) xerogels (Ta{sub 2}O{sub 5}{center_dot}6SiO{sub 2}) that are amorphous up to approximately 1100 C. A more silica-rich tantala-silica material (Ta{sub 2}O{sub 5}{center_dot}18SiO{sub 2}) was prepared via a solution-phase co-thermolytic route with 1 and HOSi(O{sup t}Bu){sub 3}, to yield a material with a Si/Ta ratio of 9/1. It was demonstrated that tantala-silica materials are active as catalysts for cyclohexene oxidation.
Prediction of Gibbs free energies of calcite-type carbonates and the equilibrium distribution of trace elements between carbonates and aqueous solutions

A linear correlation exists between the standard Gibbs free energies of formation of calcite-type carbonates (MCO3) and the corresponding conventional standard Gibbs free energies of formation of the aqueous divalent cations (M2+) at 25 °C and 1 bar ΔGMCO30 = m(ΔGf,M2+0) − 141,200 cal · mole−1 where m is equal to 0.9715. This relationship enables prediction of the standard free energies of formation of numerous hypothetical carbonates with the calcite structure. Associated uncertainties typically range from about ± 250 to 600 cal · mole−1. An important consequence of the above correlation is that the thermodynamic equilibrium constant for the distribution of two trace elements M and N between carbonate mineral and aqueous solution at 25 °C and 1 bar is proportional to the free energy difference between the corresponding two aqueous ions: In KM-N = m − 1298.15R (ΔGf,M2+0 − ΔGf,N2+0) Combination of predicted standard free energies, entropies and volumes of carbonate minerals at 25°C and 1 bar with standard free energies of aqueous ions and the equation of state in Helgesonet al. (1981) enables prediction of the thermodynamic equilibrium constant for trace element distribution between carbonates and aqueous solutions at elevated temperatures and pressures. Interpretation of the thermodynamic equilibrium constant in terms of concentration ratios in the aqueous phase is considerably simplified if pairs of divalent trace elements are considered that have very similar ionic radii (e.g., Sr2+Pb2+, Mg2+Zn2+). In combination with data for the stabilities of complex ions in aqueous solutions, the above calculations enable useful limits to be placed on the concentrations of trace elements in hydrothermal solutions.
Initial insight into why physical activity may help prevent adolescent smoking uptake

Introduction Whereas research supports the importance of regular physical activity to decrease the likelihood of smoking uptake, the mechanisms accounting for this relationship are poorly understood. We sought to determine whether the enjoyment or reward derived from physical activity is one mechanism underlying the relationship between smoking and physical activity.
Sustaining the Reading Interests of Academically Oriented ESL Students

and writing effectiveness of college freshmen. Research on the Teaching of English, 13, 197-206. Hale, G., Stansfield, C., & Duran, R. (1984). Summaries of TOEFL studies, 19631982. (Res. Rep. No. 16). Princeton, NJ: Educational Testing Service. John-Steiner, V. (1985). The road to competence in an alien land: A Vygotskian perspective on bilingualism. In J. Wertsch (Ed.), Culture, communication, and cognition: Vygotskian perspectives (pp. 348-371). Cambridge: Cambridge University Press. Klein, W., & Dittmar, N. (1979). Developing grammars. Berlin: Springer-Verlag. Light, R., Xu, M., & Mossop, J. (1987). English proficiency and academic performance of international students. TESOL Quarterly, 21(2), 251-261. Nold, E. W., & Freedman, S. W. (1977). An analysis of readers' responses to essays. Research in the teaching of English, 11: 164-174.
A Meteor Burst Model with Time-Varying Bit Error Rate

A model is described that predicts the time required to broadcast a message to an arbitrary number of receivers over a meteor burst channel, taking into account the actual time-varying nature of the bit error rate. The model computes the broadcast waiting time for any modulation scheme and choice of system parameter values using both ARQ and Hybrid ARQ/FEC error control. Example calculations are performed that find optimal data rates and packet sizes as functions of message length. Waiting times for both error control schemes are also computed and compared.
Absence of Deleterious Effects of Chronic Microwave Radiation on the Eyes of Rhesus Monkeys

Microwave irradiation of rhesus monkeys' eyes at 9.31 and 2.45 GHz and at an average power density of 150 mW per centimeter square is reported. Irradiation, beginning in 1976, of 17 monkeys (Macaca mulatta) was accomplished without restraint or anesthesia by training the monkeys to irradiate themselves. To data microwave radiation of these monkeys has not resulted in deleterious ocular effects.
Designing a pen-based flashcard application to support classroom learning environment

Pen-based Flash Cards Application ("application") offers the flexibility of handwritten input while benefiting a wide set of users to increase their memory retention. It is particularly useful in learning mathematics where typing the material using a keyboard can be difficult. In this study, we describe the observations and major findings in a two-year case study in an eighth-grade geometry class. We found that this application may enhance teacher-student interaction, increase autonomy in students for self-guided learning, and encourage collaborative learning.
Stochastic Event-Driven Molecular Dynamics

A novel Stochastic Event-Driven Molecular Dynamics (SEDMD) algorithm is developed for the simulation of polymer chains suspended in a solvent. SEDMD combines event-driven molecular dynamics (EDMD) with the Direct Simulation Monte Carlo (DSMC) method. The polymers are represented as chains of hard-spheres tethered by square wells and interact with the solvent particles with hard-core potentials. The algorithm uses EDMD for the simulation of the polymer chain and the interactions between the chain beads and the surrounding solvent particles. The interactions between the solvent particles themselves are not treated deterministically as in EDMD, rather, the momentum and energy exchange in the solvent is determined stochastically using DSMC. The coupling between the solvent and the solute is consistently represented at the particle level retaining hydrodynamic interactions and thermodynamic fluctuations. However, unlike full MD simulations of both the solvent and the solute, in SEDMD the spatial structure of the solvent is ignored. The SEDMD algorithm is described in detail and applied to the study of the dynamics of a polymer chain tethered to a hard-wall subjected to uniform shear. SEDMD closely reproduces results obtained using traditional EDMD simulations with two orders of magnitude greater efficiency. Results question the existence of periodic (cycling) motion of the polymer chain.
Experience with specifications applicable to certification

The Jet Propulsion Laboratory has developed a number of photovoltaic test and measurement specifications to guide the development of modules toward the requirements of future large-scale applications. Experience with these specifications and the extensive module measurement and testing that has accompanied their use is examined. Conclusions are drawn relative to three aspects of product certification: performance measurement, endurance testing and safety evaluation.
A Bayesian subgroup analysis with a zero‐enriched Polya Urn scheme

We introduce a new approach to inference for subgroups in clinical trials. We use Bayesian model selection, and a threshold on posterior model probabilities to identify subgroup effects for reporting. For each covariate of interest, we define a separate class of models, and use the posterior probability associated with each model and the threshold to determine the existence of a subgroup effect. As usual in Bayesian clinical trial design we compute frequentist operating characteristics, and achieve the desired error probabilities by choosing an appropriate threshold(s) for the posterior probabilities.
Assessment of key elements to determine causation and risk factors in dentistry.

The hypothesis that an exposure or characteristic is associated with a particular disease outcome can be statistically proven through large population studies. Causation studies usually involve identifying diseases that are caused by or whose natural history is modified by lifestyle choices and environmental exposures. A causal association is one in which a change in the frequency or quality of an exposure or characteristic results in a corresponding change in the frequency or quality of the disease outcome. The causal characteristics associated with an increase in disease are often called risk factors. In 1890, Robert Koch clarified the cause-and-effect relationship of infectious disease when he postulated that a bacterium was the cause of a single disease entity. He stated that the specific organism should be present in all hosts suffering from a specific disease, the microorganism should be isolated from the diseased host and grown in pure culture in the laboratory, inoculation of the cultured organism into a healthy host should cause the disease, and the microorganism should be reisolated from the inoculated host. Although not all of Koch’s postulates have proved true for all bacteria, viruses, and prions, Koch’s postulates marked a milestone for cause-and-effect thinking in health care science. Epidemiologists frequently perform causation studies. When a true cause-and-effect association is determined, this information assists in
Organizational Commitment and Involvement Explaining the Decision to Give to Associations

Charitable gifts provide vital support for the operation of many associations. Using data collected from members of six professional associations, this study examines the factors that influence cha...
Video analysis of chemotactic locomotion of stored human polymorphonuclear leukocytes.

Previous studies of the storage of polymorphonuclear leukocytes (PMNs) have used an empirical approach to define “optimal” conditions. To date, no storage conditions have been described which satisfactorily preserve the chemotactic function of PMNs beyond 24 h. In an effort to define the precise nature of the storage lesion, we studied the chemotactic locomotion of freshly isolated PMNs and PMNs which had been suspended in citrate-phosphate-dextrose-adenine (CPD-Al) plasma and stored in PVC bags, at 20–22°C for 24 h. We used time-lapse video recording and computer image analysis to quantitate the motion of PMNs migrating under agarose. The positions of individual motile cells were traced at 1-min intervals for 5 min. The following parameters were used to quantitate migration: (1) speed (distance/min), (2)) persistence of locomotion index (velocity/speed), (3) orientation angle (the angle of the vector describing the next displacement of a cell relative lo a direct line toward the chemoattractant), and (4) chemotropic index (cosine of the orientation angle). After 24 h of storage, the following changes were observed: (1) fewer cells migrated, (2) (he speed of migrating cells was reduced by 25%, (3) the persistence of locomotion index decreased by 7%, which indicates that migrating cells made slightly more/wider turns, and (4) the chemotropic index was decreased by 30%, which indicates that migrating cells were less accurate in their orientation toward the chemoattractant. Apparently, the storage of PMNs selectively impairs the ability of some cells to orient accurately in a chemotactic gradient and changes the distribution of these locomotor parameters within the population.
Constructivism: Shape-Shifting, Substance, and Teacher Education Applications.

The introduction raises basic issues about the many contradictory shapes of constructivism and the possible existence of a central substance or philosophical core that can be called constructivism. The ontological and epistemological dimensions of constructivism that help mold the different shapes are highlighted in the introduction. Next comes an analysis of constructivist shape-shifting from Piaget to the social constructivists, followed by a synthesis of any substantial tenets that might bring "identity" to constructivism. I then show how teacher education has applied some key constructivist ideas, and I evaluate the soundness of constructivism as a framework for teacher education.
Early development of the representation of the body surface in SI cortex barrel field in neonatal rats as demonstrated with peanut agglutinin binding: evidence for differential development within the rattunculus.

Physiological studies have demonstrated a highly organized somatotopic representation of the body surface in SI cortex of rat. This representation is correlated morphologically with the presence of barrel-shaped structures in layer IV. Conventional staining techniques reveal barrels in the latter part of the first postnatal week. Recently, the peroxidase conjugates of lectins, which recognize glycosylated molecules, have been used to study barrel field formation. Con A, for example, has been shown to bind primarily to prospective barrel sides and septa as early as postnatal day 3 (PND-3) in mouse. To date, investigations of SI cortex using the lectin (Arachis hypogaea) peanut agglutinin (PNA) have been confined to the study of the barrel field representation of the face and mystacial vibrissae in the mouse. In the present study we extend these findings to the development of the representation of the entire body surface called the rattunculus. Rats ranging from PND-1 (first 24 h after birth) to PND-12 were anesthetized with Nembutal and perfused with 4% paraformaldehyde and 2% glutaraldehyde in 0.2 M sodium cacodylate buffer. Brains were removed, flattened tangentially, and sectioned on a vibratome at 30–120 microns. Sections were blocked in TRIS-buffered saline (TBS) plus 2% bovine serum albumin and incubated in peanut lectin at 4° C. Following incubation, sections were washed with TBS and processed using peroxidase histochemistry. Lectin binding in the prospective forelimb representation was apparent by PND-5 whereas lectin binding to the prospective face-mystacial vibrissae representation occurred before PND-4. These results suggest that body part representations show individual variations during early pattern formation. In rat, the representation of the limbs may lag behind the representation of the face-mystacial vibrissae during early postnatal development. This developmental gradient within the cortex may reflect a differential expression of lectin receptors.
Aerosol assisted synthesis of hierarchical tin–carbon composites and their application as lithium battery anode materials

We report a method for synthesizing hierarchically structured tin–carbon (Sn–C) composites via aerosol spray pyrolysis. In this method, an aqueous precursor solution containing tin(II) chloride and sucrose is atomized, and the resultant aerosol droplets carried by an inert gas are pyrolyzed in a high-temperature tubular furnace. Owing to the unique combination of high reaction temperature and short reaction time, this method is able to achieve a hetero-structure in which small Sn particles (15 nm) are uniformly embedded in a secondary carbon particle. This procedure allows the size and size distribution of the primary Sn particles to be tuned, as well as control over the size of the secondary carbon particles by addition of polymeric surfactant in the precursor solution. When evaluated as anode materials for lithium-ion batteries, the resultant Sn–C composites demonstrate attractive electrochemical performance in terms of overall capacity, electrochemical stability, and coulombic efficiency.
The POEMS strip detector ASIC chip

Abstract In this paper we report on the design and performance of a new Application Specific Integrated Circuit (ASIC) for use with silicon strip detectors. This ASIC chip was designed for the positron–Electron Magnet Spectrometer experiment (POEMS), which has been proposed as a NASA small explorer payload. The ASIC performs as designed, with a noise figure of 800 electrons ENC with a 10 pF load, while using only 170 μ W per channel.
The DNA Damage Response: Making It Safe to Play with Knives

Damage to our genetic material is an ongoing threat to both our ability to faithfully transmit genetic information to our offspring as well as our own survival. To respond to these threats, eukaryotes have evolved the DNA damage response (DDR). The DDR is a complex signal transduction pathway that has the ability to sense DNA damage and transduce this information to the cell to influence cellular responses to DNA damage. Cells possess an arsenal of enzymatic tools capable of remodeling and repairing DNA; however, their activities must be tightly regulated in a temporal, spatial, and DNA lesion-appropriate fashion to optimize repair and prevent unnecessary and potentially deleterious alterations in the structure of DNA during normal cellular processes. This review will focus on how the DDR controls DNA repair and the phenotypic consequences of defects in these critical regulatory functions in mammals.
SIZE OF PORCINE MOTOR END-PLATES DETERMINED BY ACETYL-CHOLINESTERASE STAINING

Motor end-plates were visualized by histochemical staining for acetyl-cholinesterase in fresh frozen sections of porcine muscle. Motor end-plates in the deep red portion of the semitendinosus were larger than those in the superficial white portion even though no difference existed in size of muscle fibers.
A RAPID, AUTOMATED MICROBIOLOGICAL DETERMINATION OF ORANGE JUICE AUTHENTICITY

The microbiological method for detection of adulteration of orange juice was automated to eliminate most of the manual manipulations and reduce the assay time from over 30 hr to less than 2 hr. Commercially available components were assembled into a system that would automatically prepare, inoculate, incubate, and measure samples of orange juice. The assay was based on the rate of pH change due to acid production by a massive inoculation of Lactobacillus plantarum. The rate of pH change was proportional to the orange juice concentration, and the coefficient of multiple correlation was greater than 0.98 for most juices under the conditions of the assay.
Energy gap, excitonic, and "internal" Mn2+ optical transition in Mn-based II-VI diluted magnetic semiconductors.

The piezomodulated and the photomodulated reflectivity spectra of Mn-based diluted magnetic semiconductors (${\mathrm{Cd}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Mn}}_{\mathit{x}}$Te,${\mathrm{Zn}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Mn}}_{\mathit{x}}$ Te,${\mathrm{Cd}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Mn}}_{\mathit{x}}$Se,${\mathrm{Zn}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Mn}}_{\mathit{x}}$Se) reveal sharp signatures associated with the excitonic transitions near the band gap. The dependence of the excitonic energy on the manganese concentration (x), on temperature (T), and, in the wurtzite structure, on the polarization with respect to the optic axis, are determined from the modulation experiments. The excitonic energy in the ``hypothetical'' tetrahedrally coordinated MnTe and MnSe, viewed as the end members of the alloy systems, are deduced from the x dependence of the excitonic transition. A signature associated with ${\mathrm{Mn}}^{2+}$ is observed in piezomodulated ``pseudoreflection,'' when the energy gap is sufficiently large; its energy is insensitive to x. The absence of the Zeeman effect for the ${\mathrm{Mn}}^{2+}$ signature, in contrast to the large Zeeman effect of the excitonic feature, demonstrates that the former is an optical transition associated with the 3${d}^{5}$ shell of ${\mathrm{Mn}}^{2+}$.