cssi/SciSciGPT-SciSciNet huggingface dataset:
Feasibility Study and Demonstration of an Aluminum and Ice Solid Propellant

Aluminum-water reactions have been proposed and studied for several decades for underwater propulsion systems and applications requiring hydrogen generation. Aluminum and water have also been proposed as a frozen propellant, and there have been proposals for other refrigerated propellants that could be mixed, frozen in situ, and used as solid propellants. However, little work has been done to determine the feasibility of these concepts. With the recent availability of nanoscale aluminum, a simple binary formulation with water is now feasible. Nanosized aluminum has a lower ignition temperature than micron-sized aluminum particles, partly due to its high surface area, and burning times are much faster than micron aluminum. Frozen nanoscale aluminum and water mixtures are stable, as well as insensitive to electrostatic discharge, impact, and shock. Here we report a study of the feasibility of an nAl-ice propellant in small-scale rocket experiments. The focus here is not to develop an optimized propellant; however improved formulations are possible. Several static motor experiments have been conducted, including using a flight-weight casing. The flight weight casing was used in the first sounding rocket test of an aluminum-ice propellant, establishing a proof of concept for simple propellant mixtures making use of nanoscale particles.
A four component lattice model for nonaqueous microemulsions made with nonionic surfactants

A simple four component lattice model is used to reproduce qualitatively phase behavior of nonaqueous microemulsions. In microemulsions where glycerol and propylene glycol replace water, 2_‐3‐2 phase transitions are observed as the glycerol content in the polar organic mixture increases. The model predicts such phase behavior and reproduces the effect of oil solvophobicity and the surfactant solvophilic–lipophilic balance. In addition, temperature insensitive phase behavior is observed in these nonaqueous mixtures and is predicted in the model. The results are used to propose possible molecular interaction mechanisms which would account for the microemulsion phase behavior. The model is compared with a similar model developed for water microemulsions and the differences are cast in light of the different molecular interactions which occur between propylene glycol, water, and nonionic surfactants.
Relations between problem-solving styles and psychological adjustment in young adults: Is stress a mediating variable?

To expand on previous research on problem-focused styles of coping in adults (Heppner, Cook, Wright, & Johnson, 1995), we examined the relations between problem-solving styles and psychological adjustment (viz., life satisfaction and psychological symptoms). We also tested to see if stress may account for any associations between problem-focused styles and psychological adjustment. As expected, problem-focused styles were found to be associated with psychological adjustment. However, using latent variable analyses, stress was not found to wholly mediate the associations between problem-focused styles and psychological adjustment. Reactive style was found to have a direct link with psychological symptoms. Overall, these findings point to the importance of considering problem-focused styles in studies of psychological adjustment.
Blogging while gay and Christian: Andrew Sullivan and the production of the religious, secular, and sexual

This article examines blogger and political pundit Andrew Sullivan's performance of gay Christian identity through his weblog, The Dish. Through a reading of the repetitive and collaborative nature of The Dish as a medium of cultural production, I argue that Sullivan's gay Christian performance is made legible by how the religious and secular are articulated and negotiated through the site of the body in American culture. Sullivan's performance both reproduces and resists religious and secular normativities while at the same time produces a singular identity with distinct political and social advantages. Among other advantages, examining how the religious and secular are articulated through everyday discourse and embodied performance exposes some of the political investments in this articulation and provides a space to consider the stakes of scholars' own investments in ‘secular’ knowledge.
Gestational ethanol exposure alters the behavioral response to ethanol odor and the expression of neurotransmission genes in the olfactory bulb of adolescent rats

Fetal exposure to ethanol is highly predictive of the propensity to ingest ethanol during adolescence and in utero chemosensory plasticity has been implicated as a contributing factor in this process. Recent rodent studies have shown that fetal ethanol exposure results in a tuned unconditioned sniffing and neurophysiological olfactory response to ethanol odor in infant animals. Importantly, a significant proportion of increased ethanol avidity at this age can be attributed to the tuned behavioral response to ethanol odor. These effects are absent in adults. Using behavioral methods and comprehensive gene expression profiling to screen for robust transcriptional differences induced in the olfactory bulb, we examined whether ethanol exposure via maternal diet results in an altered responsiveness to ethanol odor that persists into late adolescence and, if so, the molecular mechanisms that may be associated with such effects. Compared to controls, fetal exposure altered: the adolescent sniffing response to ethanol odor consistent with the previously observed changes in infant animals; and the expression of genes involved in synaptic transmission and plasticity as well as neuronal development (both cell fate and axon/neurite outgrowth). These data provide evidence for a persistence of olfactory-mediated responsiveness to ethanol into the period of adolescence. Further, they provide insight into an important relationship between fetal exposure to ethanol, adolescent odor responsiveness to the drug and potential underlying molecular mechanisms for the odor-guided behavioral response.
Facilitation without inhibition

Two experiments employing the lexical decision task were conducted. In each experiment, an attempt was made to replicate Neely’s 1976 study; however, in both experiments, although facilitation was exhibited, there was never any inhibition found. Results were affected by time parameters but were affected little by the nature of the prime. Results fail to verify the two-process model of semantic memory as proposed by Neely.
Habitat Use and Ranging Behavior of Callimico goeldii

We studied the diet, habitat use, and ranging behavior of 1 group of Callimico goeldii (callimicos) over 12 mo in northwestern Bolivia. The group’s diet was comprised of fungi (39%), fruits (31%), arthropods (14%), exudates (14%), and other matter (2%). Callimicos concentrated their ranging activities in secondary forest (50%), primary forest with dense understory (30%), and bamboo (17%) habitats. The group’s total home range was 114 ha; on average they used 38.4 ha/ mo and had a day range of 925 m. Monthly average day ranges—but not monthly home ranges—increased as frugivory declined, suggesting that subjects foraged on fungi and exudates by rechecking resources within a core area, making their day ranges longer than during months when they concentrated on fruit resources. The callimicos formed polyspecific associations with tamarins (Saguinus labiatus and S. fuscicollis) during 81% of observations. Day ranges increased in months with higher association rates which appears to result from the callimicos using a broader set of habitats when with tamarins than when alone. The ranging pattern of callimicos appears to be influenced primarily by 3 factors: their seasonal shift in diet requires that they forage in a variety of habitats across the year; their depletion of resources causes them to shift their core area over time; and their lack of territorial behavior eliminates the need to patrol boundaries as part of their daily movement. As a result, callimicos differ from many other callitrichids in their low ratio of day range length to home range size.
SEQUENCE-SPECIFIC DNA CLEAVAGE BY FE2+-MEDIATED FENTON REACTIONS HAS POSSIBLE BIOLOGICAL IMPLICATIONS

Abstract Preferential cleavage sites have been determined for Fe2+/H2O2-mediated oxidations of DNA. In 50 mm H2O2, preferential cleavages occurred at the nucleoside 5′ to each of the dG moieties in the sequence RGGG, a sequence found in a majority of telomere repeats. Within a plasmid containing a (TTAGGG)81human telomere insert, 7-fold more strand breakage occurred in the restriction fragment with the insert than in a similar-sized control fragment. This result implies that telomeric DNA could protect coding DNA from oxidative damage and might also link oxidative damage and iron load to telomere shortening and aging. In micromolar H2O2, preferential cleavage occurred at the thymidine within the sequence RTGR, a sequence frequently found to be required in promoters for normal responses of many procaryotic and eucaryotic genes to iron or oxygen stress. Computer modeling of the interaction of Fe2+ with RTGR in B-DNA suggests that due to steric hindrance with the thymine methyl, Fe2+ associates in a specific manner with the thymine flipped out from the base stack so as to allow an octahedrally-oriented coordination of the Fe2+ with the three purine N7 residues. Fe2+-dependent changes in NMR spectra of duplex oligonucleotides containing ATGA versus those containing AUGA or A5mCGA were consistent with this model.
Binding of σ receptor ligands and their effects on muscarine-induced Ca2+ changes in SH-SY5Y cells☆

In human neuroblastoma SH-SY5Y cell preparations, sigma(1) receptor agonists (+)-pentazocine and 1S,2R-(-)-cis-N-[2-(3,4-dichlorophenyl)ethyl]-N-methyl-2-(1-pyrrolidinyl)cyclohexylamine (BD737) competed for [3H]haloperidol binding with K(i) values of 67+/-10 and 14+/-10 nM, respectively. (+)-Pentazocine or BD737 up to 10 microM did not affect basal levels of intracellular Ca(2+) concentration ([Ca(2+)](i)) in these cells, but they significantly reduced muscarine-induced [Ca(2+)](i) changes in a dose-related manner. However, the reduction by (+)-pentazocine was not reversed by the sigma(1) receptor antagonist haloperidol. Further studies showed (+)-pentazocine, BD737 and haloperidol could compete for [3H]quinuclidinyl benzilate binding in SH-SY5Y cells with K(i) values of 0.51+/-0.06, 0.32+/-0.07 and 4.4+/-2.3 microM, respectively. Thus, the inhibitory effects on muscarine-induced [Ca(2+)](i) changes by (+)-pentazocine and BD737 in SH-SY5Y cells were likely due to blockade of muscarinic receptors, not due to sigma(1) receptor activation by these ligands.
Science Through Children's Literature: An Integrated Approach

Instructional units integrate all areas of the curriculum and serve as models to educators at all levels. Adopted as a supplementary text in schools of education nationwide, this resource features more than 30 outstanding children's fiction books that are rich in scientific concepts yet equally well known for their strong story lines and universal appeal. Activities can be used with appropriate titles for higher grades. Grades K-3.
Precision spectroscopy with frequency combs at 3.4 μm

We discuss precision spectroscopy with a comb-based spectrometer at 3.4 μm. Our goal is to explore comb-based spectroscopy as an alternative method for fast, highly resolved, accurate measurements of gas line shapes. The spectrometer uses dual 1.5 μm frequency combs down converted to 3.4 μm via difference frequency generation (DFG) with a stabilized 1 μm fiber laser. One 3.4 μm comb is transmitted through methane and heterodyned against the second, offset comb to measure the gas absorption and dispersion. Doppler-broadened methane spectral lines are measured to below 1 MHz uncertainty. We also discuss the higher sensitivity alternative of a comb-assisted swept-laser DFG spectrometer.
Mutation of Gly721 alters DNA topoisomerase I active site architecture and sensitivity to camptothecin.

DNA topoisomerase I (Top1p) catalyzes the relaxation of supercoiled DNA via a concerted mechanism of DNA strand cleavage and religation. Top1p is the cellular target of the anti-cancer drug camptothecin (CPT), which reversibly stabilizes a covalent enzyme-DNA intermediate. Top1p clamps around duplex DNA, wherein the core and C-terminal domains are connected by extended α-helices (linker domain), which position the active site Tyr of the C-terminal domain within the catalytic pocket. The physical connection of the linker with the Top1p clamp as well as linker flexibility affect enzyme sensitivity to CPT. Crystallographic data reveal that a conserved Gly residue (located at the juncture between the linker and C-terminal domains) is at one end of a short α-helix, which extends to the active site Tyr covalently linked to the DNA. In the presence of drug, the linker is rigid and this α-helix extends to include Gly and the preceding Leu. We report that mutation of this conserved Gly in yeast Top1p alters enzyme sensitivity to CPT. Mutating Gly to Asp, Glu, Asn, Gln, Leu, or Ala enhanced enzyme CPT sensitivity, with the acidic residues inducing the greatest increase in drug sensitivity in vivo and in vitro. By contrast, Val or Phe substituents rendered the enzyme CPT-resistant. Mutation-induced alterations in enzyme architecture preceding the active site Tyr suggest these structural transitions modulate enzyme sensitivity to CPT, while enhancing the rate of DNA cleavage. We postulate that this conserved Gly residue provides a flexible hinge within the Top1p catalytic pocket to facilitate linker dynamics and the structural alterations that accompany drug binding of the covalent enzyme-DNA intermediate.
Finite-bandwidth effects on the parametric instability in an inhomogeneous plasma

The effect of a finite-bandwith pump on the parametric instability is considered. First, the temporal problem with unequal damping rates is considered, with bandwidth modelled by a Kubo-Anderson process. Exact results are obtained for both the amplitudes and power in each decay mode, with an interesting asymmetry found. Next, the spatial problem with unequal group velocities is investigated for the cases of 1) finite homogeneous interaction region, and 2) linear density profile. Thresholds and growthrates are found including both the inhomogeneity and bandwidth effects. When values typical of laser fusion parameters are inserted, it is found that bandwidth may be an important method of stabilizing Raman and Brillouin scattering.
Two-fluid Euler theory of sound dispersion in gas mixtures of disparate masses

The suitability of an Euler-level two-fluid theory to describe the behaviour of gas mixtures with disparate masses is explored for the problem of sound propagation at frequencies high enough that dispersion effects are important. The determination of the speed of propagation is reduced to solving a quadratic equation in the complex plane. The model leads to small errors of the order of the molecular mass ratio M when the molar fraction xp of the heavy gas is small (xp = O(M)), becoming increasingly inaccurate at larger values of xp. Yet agreement with He-Xe experiments is excellent for the whole range of frequencies tested, up to values of xp = 0.4. For values of xp above 0.5 our quantitative results become poorer but they still agree qualitatively with experiments, predicting small and negative dispersion coefficients and the presence of a bifurcation at critical values of the frequency and the composition. It is concluded that this generalized Euler theory provides an excellent framework within which to develop a two-fluid boundary-layer description of the peculiar dynamics of disparate-mass mixtures in the region of parameters of greatest industrial interest.
Frontiers in Seafloor Mapping and Visualization

Over the past few years there have been remarkable and concomitant advances in sonar technology, positioning capabilities, and computer processing power that have revolutionized the mapping, imaging and exploration of the seafloor. Future developments must involve all aspects of the “seafloor mapping system,” including, sonars, ancillary sensors (motion sensors, positioning systems, and sound speed sensors), platforms upon which they are mounted, and the products that are produced. Current trends in sonar development involve the use of innovative new transducer materials and the application of sophisticated processing techniques including focusing algorithms that dynamically compensate for the curvature of the wavefront in the nearfield and thus allow narrower beam widths (higher lateral resolution) at close ranges . Future developments will involve “hybrid”, phase-comparison/beam-forming sonars, the development of broad-band “chirp” multibeam sonars, and perhaps synthetic aperture multibeam sonars. The inability to monitor the fine-scale spatial and temporal variability of the sound speed structure of the water column is often a limiting factor in the production of accurate maps of the seafloor; improvements in this area will involve continuous monitoring devices as well as improved ocean models and perhaps tomography. Remotely Operated Vehicles (ROV’s) and particularly Autonomous Underwater Vehicles (AUV’s) will become more important as platforms for seafloor mapping systems. There will also be great changes in the products produced from seafloor mapping and the processing necessary to create them. New processing algorithms are being developed that take advantage of the density of multibeam sonar data and use statistically robust techniques to “clean” massive data sets very rapidly. A range of approaches are being explored to use multibeam sonar bathymetry and imagery to extract quantitative information about seafloor properties, including those relevant to fisheries habitat. The density of these data also enable the use of interactive 3-D visualization and exploration tools specifically designed to facilitate the interpretation and analysis of very large, complex, multi-component spatial data sets. If properly georeferenced and treated, these complex data sets can be presented in a natural and intuitive manner that allows the simple integration and fusion of multiple components without compromise to the quantitative aspects of the data and opens up new worlds of interactive exploration to a multitude of users.
Dynamic oversight: implementation gaps and challenges

Nanotechnology is touted as a transformative technology in that it is predicted to improve many aspects of human life. There are hundreds of products in the market that utilize nanostructures in their design, such as composite materials made out of carbon or metal oxides. Potential risks to consumers, to the environment, and to workers from the most common passive nanomaterial—carbon nanotubes—are emerging through scientific research. Newer more active nanostructures—such as cancer therapies and targeted drug systems—are also increasing in use and are raising similar risk concerns. Governing the risks to workers is the subject of this commentary. The Occupational Safety and Health Act of 1970 grants the Occupational Safety and Health Administration the legal authority to set occupational health standards to insure that no worker suffers material impairment of health from work. However, setting a standard to protect workers from nanotechnology risks may occur some time in the future because the risks to workers have not been well characterized scientifically. Alternative risk governances—such as dynamic oversight through stakeholder partnerships, “soft law” approaches, and national adoption of international consensus standards—are evaluated in this article.
Association of endometriosis with body size and figure.

Objective To determine whether body size and perceived figure, both current and historical, are associated with a diagnosis of endometriosis on laparoscopy. Design Cohort study of consecutively identified patients undergoing laparoscopy for tubal sterilization or as a diagnostic procedure. Setting Two university-affiliated hospitals. Patient(s) A cohort of 84 women aged 18–40 years. Endometriosis was visualized in 32 cases; 52 women (controls) had no visualized endometriosis, including 22 undergoing tubal sterilization and 30 with other gynecologic pathology. Intervention(s) None. Main Outcome Measure(s) Body mass index (BMI, kg/m 2 ) from self-report and perception of body figure were compared for their ability to predict case status (diagnosed endometriosis), using logistic regression models. Longitudinal trends in BMI based on perceived figure at 5-year intervals from age 15 years were compared using mixed linear models. Result(s) Based on self-report, women diagnosed with endometriosis were taller, thinner, and had a significantly lower BMI. In this series, cases were more likely to be late maturers (menarche at ≥14 y) and late to initiate sexual activity (≥21 y), and they were less likely to be gravid, parous, and a current smoker. Adjusting for age (in years), being tall (height ≥68 in), and parity (yes vs. no), a higher current BMI was statistically protective for a diagnosis of endometriosis, regardless of whether BMI was determined by self-report (adjusted odds ratio [AOR] = 0.88, 95% confidence interval [CI] 0.79–0.99) or from perceived figure (AOR = 0.86, 95% CI 0.75–0.99). For every unit increase in BMI (kg/m 2 ), there was an approximate 12%–14% decrease in the likelihood of being diagnosed with endometriosis. In an adjusted repeated measures model, BMI was 21.3 ± 0.6 kg/m 2 (estimate ± SE) for women with endometriosis, compared with 23.2 ± 0.4 kg/m 2 for the controls, a difference over all ages of −1.9 ± 0.8 kg/m 2 . This is a consistent difference of about 10 lb at every age, assuming an average height of about 64.5 in. Conclusion(s) In a laparoscopy cohort, women diagnosed with endometriosis were found to have a lower BMI (leaner body habitus), both at the time of diagnosis and historically. That women diagnosed with endometriosis may have a consistently lean physique during adolescence and young adulthood lends support to the suggestion of there being an in utero or early childhood origin for endometriosis.
Experimental characterization and modeling of electron saturation velocity in MOSFETs inversion layer from 90 to 350 K

From saturation transconductance of devices of 0.25- mu m CMOS technology, the saturation velocity of electrons ( nu /sub sat/) in the inversion layer from 90 to 350 K has been determined. The extracted nu /sub sat/ at 300 K was 7.86*10/sup 6/ cm/s, which is significantly lower than that of bulk silicon ( nu /sub sat-blk/) and has a much weaker temperature dependence. The ratio nu /sub sat-blk// nu /sub sat/ is 1.27 at 300 K, and is increased to 1.68 at 90 K. Consistent values of nu /sub sat/ have been determined for devices of three vastly different MOS technologies, demonstrating the technology independence of nu /sub sat/. The results are useful for developing and testing theoretical carrier transport models, and are of practical importance in estimating the ultimate speed performance of surface MOSFETs. An empirical model for nu /sub sat/ as a function of temperature has also been derived for application in predictive device simulation. >
Optical-heterodyne generation in low-temperature-grown GaAs up to 1.2 THz

Low-temperature-grown, non-stoichiometric GaAs is used as an optical mixer to generate coherent output radiation up to a frequency of 1.2 THz. The mixer structure consists of an epitaxial layer of the LTG GaAs material with submicron interdigitated electrodes fabricated on the top surface. Terahertz photocurrents are generated in the gaps between the electrodes and power is radiated by coupling these currents efficiently into a self-complementary spiral antenna. The experimental roll-off in photomixer output power is explained by two time constants - one for the electron-hole recombination time of 0.35 ps and the other for the photomixer-antenna RC time constant of 0.62 ps. The photomixer demonstrates the capability to generate continuous-wave radiation in a spectral region where tunable coherent radiation has been lacking.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
Expression in transgenic mice of dominant interfering Fas mutations: a model for human autoimmune lymphoproliferative syndrome.

Most humans with autoimmune lymphoproliferative syndrome (ALPS) carry heterozygous dominant mutations in one allele of the gene encoding Fas/APO-1/CD95. ALPS patients, like Fas-deficient MRL lpr/lpr mice, have lymphoproliferation, autoimmunity, increased CD4(-)/CD8(-) T lymphocytes, and apoptosis defects. Consistent with the phenotypic variability of lpr/lpr mice of different background strains, human genetic studies indicate that a Fas mutation is insufficient to induce ALPS in all mutation carriers. To investigate the dominant function of human Fas mutations and the additional genetic factor(s) involved in the development of ALPS, we generated transgenic mice expressing, in addition to endogenous Fas, mouse Fas molecules bearing mutations in the intracellular death domain corresponding to mutations identified in ALPS patients. Transgenic mice developed mild features of ALPS, including hepatosplenomegaly, elevated proportions of lymphocytes in spleen and lymph nodes, apoptotic defects, and hepatic lymphocytic infiltrates. Therefore defective murine Fas proteins act in a dominant manner to impair apoptosis of activated lymphocytes and disrupt lymphocyte homeostasis. The influence of genetic background on phenotype was studied by comparing transgenic mice on FVB/N and (FVB/N x MRL) backgrounds with syngenetic control mice and with MRL and MRL lpr/lpr mice. While expression of transgenic mutant Fas contributed mainly to hepatosplenomegaly and accumulation of lymphocytes, MRL background genes played a major role in the production of autoantibodies and elevated serum immunoglobulin levels. Moreover, compared to FVB/N (+/+) mice, a substantial Fas-specific apoptotic defect was found in MRL (+/+) mice, suggesting a mechanism for the known tendency of this strain to develop autoimmunity.
Effects of temporary cementation on permanent cement retention to composite resin cores

This in vitro study compared the effects on retention of base metal cylindrical retainers placed on composite resin cores when pretreated with eugenol and noneugenol temporary cements. Sixty composite cores and base metal cylindrical retainers were tested. The cores were pretreated with eugenol and noneugenol temporary cements before eventual cementation with resin and zinc phosphate cements. Cemented core retention was measured by application of a compressive force to the cores in an Instron machine. Differences were found between the two permanent cements. Pretreatment with eugenol cement reduced retainer retention with resin cements, but had no effect with zinc phosphate cement. Pretreatment with noneugenol cement did not reduce retainer retention.
PROBING ASPECTS OF NONLINEAR CONDUCTION IN ELECTRORHEOLOGICAL SUSPENSIONS

Particle and electrode surfaces were altered to examine the effects on the electrorheological response of barium titanate/silicone oil suspensions. Unmodified suspensions exhibited nonlinear conduction. The dynamic yield stresses scaled as En, where n<2 at all electric field frequencies, and the current had substantial harmonic content, a hallmark of nonlinear conduction. Modifying the particle surfaces did not affect these nonlinear responses. Casting polymers on the electrode surfaces changed the responses. With polymer coatings, the dynamic yield stresses scaled as En, where n≥2 at some frequencies and increased with coating thickness. With coated electrodes, the current harmonic contents were significantly decreased. These results suggest that nonlinear conduction in ER suspensions is associated with charge injection at the electrode/liquid interface.
From automata to fluid flow: Comparisons of simulation and theory.

Lattice-gas automata have been proposed as a new way of doing numerical calculations for hydrodynamic systems. Here, a lattice-gas simulation is run to see whether its behavior really does correspond, as proposed, to that of the Navier-Stokes equation. The geometry used is the two-dimensional version of laminar pipe flow. Three checks on the existing theory are performed. The parabolic profile of momentum density arising from the dynamics is quantitatively verified. So is the equation of state, which arises from the statistical mechanics of the system. Finally, the well-known logarithmic divergence in the viscosity is observed in the automaton and is shown to disagree with the earliest theoretical predictions in this system. Proper agreement is achieved, however, when the theory is extended to include three extra (recently discovered) conserved quantities. In this way, checks of both linear and nonlinear parts of the hydrodynamic description of lattice-gas automata have been achieved.
Vertebrate proteins related to Drosophila Naked Cuticle bind Dishevelled and antagonize Wnt signaling.

Abstract Wnt signals control cell fate decisions and orchestrate cell behavior in metazoan animals. In the fruit fly Drosophila, embryos defective in signaling mediated by the Wnt protein Wingless (Wg) exhibit severe segmentation defects. The Drosophila segment polarity gene naked cuticle ( nkd ) encodes an EF hand protein that regulates early Wg activity by acting as an inducible antagonist. Nkd antagonizes Wg via a direct interaction with the Wnt signaling component Dishevelled (Dsh). Here we describe two mouse and human proteins, Nkd1 and Nkd2, related to fly Nkd. The most conserved region among the fly and vertebrate proteins, the EFX domain, includes the putative EF hand and flanking sequences. EFX corresponds to a minimal domain required for fly or vertebrate Nkd to interact with the basic/PDZ domains of fly Dsh or vertebrate Dvl proteins in the yeast two-hybrid assay. During mouse development, nkd1 and nkd2 are expressed in multiple tissues in partially overlapping, gradient-like patterns, some of which correlate with known patterns of Wnt activity. Mouse Nkd1 can block Wnt1-mediated, but not β-catenin-mediated, activation of a Wnt-dependent reporter construct in mammalian cell culture. Misexpression of mouse nkd1 in Drosophila antagonizes Wg function. The data suggest that the vertebrate Nkd-related proteins, similar to their fly counterpart, may act as inducible antagonists of Wnt signals.
Preparation of (Me3CC5H4)4M2(μ-Me)2 (M Ce or U) and the crystal structure of the cerium derivative

Abstract The bridging methyl compound, (Me 3 CC 5 H 4 ) 4 Ce 2 (μ-Me) 2 , has been prepared from (Me 3 CC 5 H 4 ) 3 Ce or (Me 3 CC 5 H 4 ) 4 Ce 2 (μ-SCHMe 2 ) 2 and MeLi in hydrocarbon solvents. The solid state X-ray structure of the cerium methyl shows that the methyl groups bridge the two (Me 3 CC 5 H 4 ) 2 Ce units in a symmetrical fashion in such a way that the geometry at cerium is four coordinate and pseudo-tetrahedral. The CeC(μ-Me) distance is 2.665(6) A and the CeC(σ-Me)Ce angle is 89.9(3)°. All the hydrogen atoms were located and refined isotropically; CH (ave.) = 0.85 A and HCH (ave.) = 108° for the bridging methyl group. The geometry of the bridging methyl group in (Me 3 CC 5 H 4 ) 4 Ce 2 (μ-Me) 2 is similar to that in Me 4 Al 2 (μ-Me) 2 . The uranium methyl was obtained from the reaction of (Me 3 CC 5 H 4 ) 3 U with MeLi. The cerium and uranium methyls are unstable in the gas phase and in benzene solution, since they rearrange to give (Me 3 CC 5 H 4 ) 3 M (M  Ce or U) and other materials.
The AGAAAAGA Palindrome in PrP Is Required to Generate a Productive PrPSc-PrPC Complex That Leads to Prion Propagation

The molecular hallmark of prion disease is the conversion of normal prion protein (PrPC) to an insoluble, proteinase K-resistant, pathogenic isoform (PrPSc). Once generated, PrPSc propagates by complexing with, and transferring its pathogenic conformation onto, PrPC. Defining the specific nature of this PrPSc-PrPC interaction is critical to understanding prion genesis. To begin to approach this question, we employed a prion-infected neuroblastoma cell line (ScN2a) combined with a heterologous yeast expression system to independently model PrPSc generation and propagation. We additionally applied fluorescence resonance energy transfer analysis to the latter to specifically study PrP-PrP interactions. In this report we focus on an N-terminal hydrophobic palindrome of PrP (112-AGAAAAGA-119) thought to feature intimately in prion generation via an unclear mechanism. We found that, in contrast to wild type (wt) PrP, PrP lacking the palindrome (PrPDelta112-119) neither converted to PrPSc when expressed in ScN2a cells nor generated proteinase K-resistant PrP when expressed in yeast. Furthermore, PrPDelta112-119 was a dominant-negative inhibitor of wtPrP in ScN2a cells. Both wtPrP and PrPDelta112-119 were highly insoluble when expressed in yeast and produced distinct cytosolic aggregates when expressed as fluorescent fusion proteins (PrP::YFP). Although self-aggregation was evident, fluorescence resonance energy transfer studies in live yeast co-expressing PrPSc-like protein and PrPDelta112-119 indicated altered interaction properties. These results suggest that the palindrome is required, not only for the attainment of the PrPSc conformation but also to facilitate the proper association of PrPSc with PrPC to effect prion propagation.
Volumes and heat capacities of aqueous solutions of ammonium chloride from the temperatures 298.15 K to 623 K and pressures to 28 MPa

Abstract Densities of aqueous solutions of NH 4 Cl at molalities ranging from 0.1 mol·kg −1 to 6.0 mol·kg −1 , temperatures from 298.15 K to 623 K, and pressures of 10 MPa and 28 MPa were measured using a vibrating tube flow densitometer. Heat capacities of the above solutions at temperatures from 302 K to 623 K and a pressure of 28 MPa were measured using a flow heat-capacity calorimeter. The volumetric and calorimetric results for NH 4 Cl(aq) are in good agreement with the literature data at low temperatures. At high temperatures, observed volumes and heat capacities of HN 4 Cl(aq) are consistent with the assumption of strong electrolyte behavior, with only small effects from reactions to form NH 3 (aq), H + (aq), and HCl(aq), and from ion pairing of NH 4 + (aq) with Cl − (aq).
Support for basic psychological needs in the context of HIV disclosure for older youth

Abstract Purpose This study utilized Self-Determination Theory's sub-theory Basic Needs Theory (Deci & Ryan, 2000) to understand older youths' perceptions of support for their basic needs of autonomy, relatedness, and competence in the context of disclosing their HIV status. Methods Semi-structured interviews lasting 10–60 min each were conducted with nine youth aged 17–19 (4 women and 5 men) and two adult staff at a one-week residential program in a large southern city. Participant observations of disclosure-related conversations and experiences were conducted and recorded throughout the program. Reliability and validity assurances were met in multiple ways. Analysis of the content of interviews and observations indicated consistent themes that converged on the research questions. Results When participants perceived more support for their basic psychological needs for autonomy, relatedness, and competence, they reported more self-determined motivation to disclose their status and better satisfaction with their decisions. The results of this study indicate that Basic Needs Theory is useful for understanding how the basic psychological needs of autonomy, relatedness, and competence are satisfied or thwarted in the context of HIV disclosure for older youth. Conclusions Programs and people working with older youth with HIV/AIDS can use BNT to help youth identify, create, and adapt contexts to be supportive of their basic needs for autonomy, relatedness, and competence, and provide guidance and support accordingly. Providers can utilize this information to support youth in strategizing about their disclosure decisions and goals for their well-being.
The failure of methamphetamine hydrochloride to produce dissociation of an escape response

Twenty-seven albino rats were trained to make an escape response at one of two dosage levels of methamphetamine or in a placebo state. Subsequently, they were tested in both drug states, as well as in the nondrugged state, to determine if the conditioned response was associated with the specific drug condition of the organism during training. Virtually no dissociation was observed across different states. Animals trained at one dosage level responded in like fashion when tested at another dosage level and/or after an injection of physiological saline. Possible reasons for the lack of dissociation appeared to be the nature of the task and the minimal potential of methamphetamine to produce state-dependent conditioning.
Ordinary and proper location M-estimates for autoregressive-moving average models

SUMMARY Proper location M-estimates for a model with non-Gaussian autoregressive-moving average type errors are genuine maximum likelihood type estimates, whereas ordinary location M-estimates are those introduced by P. Huber for independent and identically distributed errors. The relative behaviour of ordinary location M-estimates and proper location M-estimates is studied for situations with dependent errors of purely autoregressive and purely moving average type. It is shown through asymptotic calculations and finite-sample size Monte Carlo studies that although ordinary location M-estimates are adequate for weak dependency structure, they can be quite inefficient compared with proper M-estimates of location when the non-Gaussian errors have a moderate to strong dependency structure.
High open-circuit voltages on thin silicon solar cells

Silicon heterostructures solar cells have very low surface recombination and the resulting cells can achieve high open circuit voltages. We have demonstrated an open circuit voltage for a silicon solar cell at 753 mV. We show high lifetimes on textured substrates with an average of 3 ms using thin layers of doped and intrinsic amorphous silicon and that the lifetimes are consistent across batches. We show that for high measured lifetimes there is a close match between the Implied V OC (measured from photoconductance) and the Actual V OC (as measured on a final cell). Recent measurements with have produced Implied V OC 's of 761 mV on textured substrates.
The effect of micron sized wood fibers in wood plastic composites

The popularity and demand for wood plastic composites (WPC) has focused research on fiber properties associated with performance. In this study, maple wood fibers (WF) were ball milled and classified into discrete size fractions. Fiber analyses showed only three distinct WF size classes (80-100, 100-200 and <200 mesh). High density polyethylene (HDPE) based WPC were made from classified WF (10 to 50%). The effect of WF size, loading, and maleated polyethylene (MAPE) coupling agent on WPC rheological behavior (torque rheometry and melt flow rate (MFR)) and flexural properties were examined. The WPC MFR decreased with wood loading, increased with a reduction in WF size. The modulus of rupture (MOR) was shown to increase with a reduction in WF size and increase with the addition of MAPE. The increase in MOR is likely due to an increase in the interfacial interaction between the polymer and WF. Modulus of elasticity (MOE) was shown to increase with an increase in wood loading and decrease with a decrease in WF size. The toughness of the WPC was shown to increase with a decrease in WF size and increase upon addition of MAPE.
Cocaine Politics: Drugs, Armies and the CIA in Central America

Cocaine Politics: Drugs, Armies and the CIA in Central America. Peter Dale Scott and Jonathan Marshall. Berkeley: University of California Press, 1991. 279pp. $24.95 (cloth). ISBN 0–520–07312–6.
The importance of pairwork in interdisciplinary and educational initiatives

An early and prominent employee of Google, Georges Harik, recently made the assertion that pairs working together in startups are 20 times more productive than individuals working alone. The author has also personally experienced the boost of what is here termed pairwork in a university setting during the startup phase of several educational and interdisciplinary initiatives. The paper briefly explores pairwork in the history of technology and constructs both qualitative and little quantitative models of pairwork. The quantitative model under reasonable assumptions easily recovers Harik's 20x boost. The paper also briefly examines the author's recent experiences with pairwork in four interdisciplinary and educational initiatives.
Efficient indexing methods for temporal relations

The primary issues that affect the design of indexing methods are examined, and several structures and algorithms for specific cases are proposed. The append-only tree (AP-tree) structure indexes data for append-only databases to help event-join optimization and queries that can exploit the inherent time ordering of such databases. Two variable indexing for the surrogate and time is discussed. It is shown that a nested index could be a very efficient structure in this context and is preferable to a composite B-tree or an index that involves linear lists of historical tuples. The problems of indexing time intervals, as related to nonsurrogate joint-indexing, are discussed. Several algorithms to partition the time line are introduced. A two-variable AT index based on nested indexing is outlined. >
Characterization of the Descemet's membrane/posterior collagenous layer isolated from Fuchs' endothelial dystrophy corneas.

Abstract The combined Descemet's membrane (DM) and posterior collagenous layer (PCL) of Fuchs' endothelial dystrophy corneas were isolated and characterized by biochemical and immunofluorescence methods. The amino acid composition of the Fuchs' DM-PCL was similar to age-matched normal Descemet's membranes (DM). As determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and 125 I two-dimensional peptide mapping, normal DM and Fuchs' DM-PCL contained the same collagen types [type IV and endothelial cell (EC) collagen], but a slight discrepancy was seen in the electrophoretic mobility of some collagen chains. Immunofluorescence staining localized fibrinogen/fibrin to Fuchs' DM-PCL but not to normal DM. These data suggest (1) that the appearance of 110 nm banded material in sheets and fusiform bundles characteristic of Fuchs' PCL is not due to the presence of a new (abnormal) collagen type but may represent altered assembly of collagen molecules, and (2) that the fibrinolytic system may play a role in the degenerative process of Fuchs' endothelial dystrophy.
Circulatory dynamics during the cold pressor test

Abstract Circulatory dynamics during the cold pressor test were studied in 10 normotensive and 8 hypertensive patients. Measurements were made before and during 5 minutes of immersion of the hand in ice water. The initial 60 seconds of the test represented vascular reactivity to the cold stimulus, and the hemodynamics at 5 minutes of hand immersion represented the degree of circulatory adaptation to this stimulus. Most patients responded to the cold pressor test with statistically significant increases in blood pressure. However, only 50 per cent of hypertensive patients demonstrated vascular hyperreactivity, i.e., a rise in blood pressure of 20/20 mm. Hg or more. In addition, the pressor responses were quantitatively similar in the hypertensive and normotensive groups. These data indicate that the pressor reaction to the cold stimulus is not altered in hypertension. The cold pressor test represents a widespread stimulation (neurogenic) of multiple components of the cardiovascular system, the quantitative and qualitative aspects of which are not predictable on a clinical basis and are similar in hypertensive and normotensive individuals. Major cardiodynamic changes during this stimulus, in addition to the pressor response, include increased peripheral arterial resistance, increased cardiac output due to increased heart rate, and increased pulmonary artery pressures. Cold adaptation, an almost universal occurrence, generally involves a gradual diminution in the pressor response, and the circulatory mechanisms responsible for it, to continued (cold) stimulation. The usefulness of this phenomenon in the study of the cardiovascular system in normal and hypertensive patients is negligible.
Sustainable Reservoir Operation: Can we Generate Hydropower and Preserve Ecosystem Values?

Hydroelectric power provides a cheap source of electricity with few carbon emissions. Yet, reservoirs are not operated sustainably, whichwedefineasmeetingsocietalneedsforwaterandpowerwhileprotectinglong-termhealthoftheriverecosystem.Reservoirs that generate hydropower are typically operated with the goal of maximizing energy revenue, while meeting other legal water requirements. Reservoir optimization schemes used in practice do not seek flow regimes that maximize aquatic ecosystem health. Here, wereviewoptimizationstudiesthatconsideredenvironmental goalsinone ofthree approaches.Thefirstapproachseeksflow regimes that maximize hydropower generation, while satisfying legal requirements, including environmental (or minimum) flows. Solutionsfromthisapproachareoftenusedinpracticetooperatehydropowerprojects.Inthesecondapproach,flowreleasesfroma dam are timed to meet water quality constraints on dissolved oxygen (DO), temperature and nutrients. In the third approach, flow releases are timed to improve the health of fish populations. We conclude by suggesting three steps for bringing multi-objective reservoir operation closer to the goal of ecological sustainability: (1) conduct research to identify which features of flow variation are essential for river health and to quantify these relationships, (2) develop valuation methods to assess the total value of river health and (3) develop optimal control softwares that combine water balance modelling with models that predict ecosystem responses to flow. Published in 2008 by John Wiley & Sons, Ltd.
Control Channel Establishment in Cognitive Radio Networks using Channel Hopping

In decentralized cognitive radio (CR) networks, enabling the radios to establish a control channel (i.e., "rendezvous" to establish a link) is a challenging problem. The use of a dedicated common control channel simplifies the rendezvous process but may not be feasible in many opportunistic spectrum sharing scenarios due to the dynamically changing availability of all the channels, including the control channel. To address this problem, researchers have proposed the use of channel hopping protocols for enabling rendezvous in CR networks. Most, if not all, of the existing channel hopping schemes only provide ad hoc approaches for generating channel hopping sequences and evaluating their properties. In this paper, we present a systematic approach, based on quorum systems, for designing and analyzing channel hopping protocols for the purpose of control channel establishment. The proposed approach, called Quorum-based Channel Hopping (QCH) system, can be used for implementing rendezvous protocols in CR networks that are robust against link breakage caused by the appearance of incumbent user signals. We describe two synchronous QCH systems under the assumption of global clock synchronization, and two asynchronous channel hopping systems that do not require global clock synchronization. Our analytical and simulation results show that the proposed channel hopping schemes outperform existing schemes under various network conditions.