cssi/SciSciGPT-SciSciNet huggingface dataset:
NMR Second Site Screening for Structure Determination of Ligands Bound in the Hydrophobic Pocket of HIV-1 gp41

The development of non-peptide fusion inhibitors through rational drug design has been hampered by the limited accessibility of the gp41 coiled coil target, which is highly hydrophobic, and the absence of structural data defining details of small molecule interactions. Here we describe a new approach for obtaining structural information on small molecules bound in the hydrophobic pocket of gp41, using a paramagnetic probe peptide which binds adjacent to the pocket along an extended coiled coil. Ligand binding in the pocket leads to paramagnetic relaxation effects or pseudocontact shifts of ligand protons. These effects are distance and / or orientation dependent, permitting determination of ligand pose in the pocket. The method is demonstrated with a fast-exchanging ligand. Multiple measurements at different coiled coil and probe peptide ratios enabled accurate determination of the NMR parameters. Use of a labeled probe peptide stabilizes an otherwise aggregation-prone coiled coil, and also enables modulation of the paramagnetic effect to study ligands of various affinities. Ultimately, this technique can provide essential information for structure-based design of non-peptide fusion inhibitors.
Nonlinear mode conversion of VLF waves over Arecibo, Puerto Rico

We investigate a mechanism occurring in the ionosphere that can cause nonlinear mode conversion of incident VLF radio waves into lower hybrid waves. Both the Spread-F and Sporadic-E structures can provide the density irregularities for this mechanism to occur. Since the irregularities in Sporadic-E have shorter scale than those produced in Spread-F, it is expected that the mode converted lower hybrid waves in E-region will have much higher intensity than those in F-region. Based on the proposed hypothesis, this mechanism will broaden the spectrum of the incident VLF waves. To simulate this scenario and corroborate this mechanism, experiments were conducted using the 430 MHz Incoherent Scatter Radar (ISR) at Arecibo Observatory, Puerto Rico. The ground based Naval Transmitter code-named NAU was the source transmitting 40.75 kHz VLF waves continuously at 100 kW power. Electrons accelerated by mode-converted lower hybrid waves along the earth magnetic field were detected by the ISR Radar in the form of weak plasma lines in both E-region and F-region. The detected plasma lines possessed symmetric spectrum features, showing that the accelerated electron streams were bi-directional. It indicates that the mode-converted electrostatic wave could propagate at either direction along the earth magnetic field. The intensity of the plasma lines detected in E-region was about an order of magnitude higher than those detected in F-region as expected.
An asynchronous decomposition approach to parallel global optimization

Abstract We introduce an alternating decomposition approach for solving global optimization problems on parallel computers. The method is based on decomposing moves in the state space into components which can be optimized concurrently. A number of features distinguish our approach from others which have been proposed in the literature. We report the results of applying the approach to energy minimization of Lennard-Jones clusters using simulated annealing. We find that the new approach is robust, has high parallel efficiency, and it can rapidly generate a good approximation to the molecular conformation.
Theoretical and Experimental Studies of the Effects of Heat, EDTA, and Enzyme Concentration on the Inactivation Rate of α‐Amylase from Bacillus sp.

The effects of calcium ion-chelating ligand (EDTA), heat, and enzyme concentration on the stability of a metalloenzyme (α-amylase, from Bacillus sources) solution have been examined by experimental as well as theoretical studies. A simple two-stage inactivation model has been presented that explicitly includes the calcium ion concentration and can explain all experimental results. The first stage involves a reversible inactivation process caused by the dissociation of a metal ion (Ca 2+ ) from the active enzyme molecule, followed by the second stage of inactivation in which the apoenzyme (protein without the metal) undergoes an irreversible thermal inactivation (denaturing). These studies also suggest that the diluted enzyme solution is more prone to inactivation than the concentrated enzyme solution.
The structures of two sodium uranyl compounds relevant to nuclear waste disposal

Abstract Single crystals of two sodium uranyl phases, Na2[(UO2)3O3(OH)2] and Na4(UO2)2(Si4O10)2(H2O)4 (designated NAUOH and NAURSI, respectively), were hydrothermally synthesized. Na uranyl oxyhydroxide (NAUOH) is monoclinic, space group P21/n, a=0.70476(3) nm, b=1.14126(6) nm, c=1.20274(6) nm, β=90.563(1)°, V=0.96733(8) nm 3 . The structure of NAUOH was solved by direct methods and refined on the basis of F2 for 4027 unique reflections measuring using Mo Kα X-radiation and a CCD-based Smart APEX detector. The agreement index (R1) is 2.7%, calculated using 2955 unique observed reflections (|Fo|⩾4σF), and the goodness-of-fit is 0.68. The structure contains uranyl pentagonal bipyramids that share vertices and edges, forming sheets parallel to (0 1 0). The sheets are linked by double chains of Na polyhedra located in the interlayer. NAUOH is a Na analogue of the mineral compreignacite, and may correspond to the Na uranyl oxide hydrate formed in studies of the oxidative dissolution of spent nuclear fuel. The phase Na4(UO2)2(Si4O10)2(H2O)4 (NAURSI) is the Na analogue of KNa3(UO2)2(Si4O10)2(H2O)4, which was found as an alteration phase on hydrothermally treated actinide-bearing borosilicate waste glass. It is monoclinic, space group C2/m, a=1.2770(1) nm, b=1.3610(1) nm, c=0.82440(8) nm, β=119.248(2)°, V=1.2501(2) nm 3 . The structure of NAURSI was solved by direct methods and refined on the basis of F2 for 1483 unique reflections measured with Mo Kα X-radiation and a CCD-based Smart 1 K detector. The agreement index (R1) is 1.9%, calculated using 1333 unique observed reflections (|Fo|⩾4σF), and the goodness-of-fit is 1.08. The structure is based on a uranyl silicate framework, with Na cations and H2O groups located in interstitial sites. The structure is closely related to that of KNa3(UO2)2(Si4O10)2(H2O)4.
SITE-DIRECTED MUTANTS OF POST-TRANSLATIONALLY MODIFIED SITES OF YEAST EEF1A USING A SHUTTLE VECTOR CONTAINING A CHROMOGENIC SWITCH

Eukaryotic elongation factor 1A (eEF1A, formerly eEF-1 alpha) carries aminoacyl-tRNAs into the A-site of the ribosome in a GTP-dependent manner. In order to probe the structure/function relationships of eEF1A, we have generated site-directed mutants using a modification of a highly versatile yeast shuttle vector, which consists of the insertion of a 66 base long synthetic DNA fragment in the vector's polylinker. Via oligonucleotide-directed mutagenesis, the modification permits the identification of mutant clones based on a chromogenic screen of beta-galactosidase activity. Mutagenesis reactions are performed with two or more oligonucleotides, one introducing the chromogenic shift, and the other(s) introducing the mutation(s) of interest in eEF1A. Several rounds of chromogenic shifts and additional mutations can be performed in succession on the same vector. To address the possible function of the methylated lysines in yeast eEF1A, we have changed the post-translationally modified lysines (residue 30, 79, 316 and 390) to arginines using the above methodology. Yeast with eEF1A mutants that substitute arginine in all four sites do not show any phenotypic change. There is also an apparent equivalency of wild-type and mutant yeast eEF1A in in vitro assays. It is concluded that the post-translational modifications of eEF1A are not of major importance for eEF1A's role in translation.
Effect of the surface active agents on the rheology of aqueous alumina slips

Abstract In order to understand the properties of concentrated alumina slips with particular reference to their stability behavior, both electrophoresis and rheology experiments were carried out on three commercial alumina powders in three cationic surface active agents. The results suggest that all three commercial alumina powders used in this investigation are associated with some surface impurity that resembles sodium citrate and all three additives are adsorbed on the alumina particle surface. The net surface negative charge decreased with the addition of the additives for additive concentrations below 1% (wt), and above 1% (wt) it appears that the additive remains electrophoretically neutral. While the slips prepared in water and the additive solutions for concentrations above 1% (wt) were very stable, with low viscosity and Newtonian type fluid behavior, the alumina dispersions containing 0.5% (wt) additive solutions were flocculated and exhibited pseudo plastic fluid type properties. It appears that while at low additive concentrations, both the rheology of the slip and the electrophoretic mobility of the alumina particles is governed by the electrostatic interactions, steric effects are responsible for the state of the slip at high concentrations.
Phase-Transformation Wave Dynamics in LiFePO4

A general continuum model has recently been proposed for the dynamics of ion intercalation in a single crystal of rechargeable-battery electrode materials [1]. When applied to strongly phase-separating, highly anisotropic materials such as LiFePO4, phase-transformation waves are predicted between the lithiated and unlithiated portions of a crystal. In this paper, we extend the analysis of the wave dynamics, and we describe a new mechanism for current capacity fade through the interactions of these waves with defects in the material.
MODELING AND VISUALIZATION OF QUANTUM BIFURCATIONS IN PHASE SPACE

We investigate quantum-mechanical counterpart of a classical instability in a phase space by the numerical method of quantum trajectories with moving basis. As an application the model of coupled two oscillators driven by a monochromatic force in the presence of dissipation (intracavity second harmonic generation) is analyzed. The system of interest is characterized by two bifurcations leading to ranges of instability: the Hopf bifurcation which connects a steady state dynamics of the oscillatory modes to a self-pulsing temporal dynamics and the bifurcation of the period-doubling. The both two regimes are analyzed on the framework of the semiclassical phase trajectories and the Wigner functions of the oscillatory modes in phase space.
Fractal image coding based on a theory of iterated contractive image transformations

The notion of fractal image compression arises from the fact that the iteration of simple deterministic mathematical procedures can generate images with infinitely intricate geometries known as fracial images [2]. The purpose of research on fractalbased digital image coding is to solve the inverse problem of constraining this complexity to match the realworld complexity of realworld images. In this. paper we propose a fractal image coding technique based on a mathematical theory of iterated transformations [1 2 3 7] which encompasses deterministic fractal geometry. Initial results were reported in [7 8]. The main characteristics of this technique are that (i) it is fractal in the sense that it approximates an original image by a fractal image and (ii) it is a blockcoding technique which relies on the assumption that image redundancy can be efficiently exploited through blockwise selfiransformabiliiy. We therefore refer to it as fracial blockcoding. The codingdecoding system is based on the construction for each original image given to encode of a specific image transformation which when iterated on any initial image produces a sequence of images which converges to a fractal approximation of the original. We show how to design such coders and thoroughly describe the implementation of a system for monochrome still images. Extremely promising coding results were obtained.© (1990) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
Translocation (1;3)(p36;q21) in secondary leukemia

A case of acute nonlymphocytic leukemia (M4) secondary to treatment for multiple myeloma is described. The patient presented a translocation t(1;3)(p36;q21) and monosomy 7.
Physical Operations, Diagram Operations

Operations on diagrams are examined as part of a search for a model of superposition. Diagram operations are required to represent physical processes.
Spin-polarized electron-energy-loss spectroscopy on Ni.

High-resolution spin-polarized electron-energy-loss data on Ni(110) are presented. Exchange scattering is found to be the dominant loss mechanism. The Stoner excitation spectrum shows a sharp threshold around 65-meV energy loss (Stoner gap). The energy-loss probability for spin-down electrons is up to 3 times larger than for spin-up electrons. An interpretation in terms of the Ni 3d band structure is given.
Non-histone lysine acetylated proteins in heart failure

Both histone-acetylations and histone deacetylases have been shown to play a key role in cardiac remodeling. Recently, it has become abundantly clear that many non-histone proteins are modified by post-translational lysine acetylations and that these acetylations regulate protein activity, conformation, and binding. In the present study, non-histone acetylated proteins associated with heart failure were identified. Global screening for lysine acetylated proteins was performed using 2-dimensional gel electrophoresis coupled with immunoblotting with a primary monoclonal anti-acetyl-lysine antibody. Lysine acetylated proteins were compared in two rodent models of hypertensive heart failure, the Dahl salt-sensitive (SS) and spontaneously hypertensive heart failure prone (SHHF) rats with those in corresponding controls, i.e., the Dahl salt-resistant (SR) and W (W) rat strains, respectively. Forty-one and 66 acetylated proteins were detected in SS and SHHF failing hearts, respectively, but either not detected or detected with less abundance in corresponding control hearts. Twelve of these acetylated proteins were common to both models of heart failure. These were identified using matrix-assisted laser desorption/ionization time of flight (MALDI-TOF/TOF) mass spectrometry followed by Mascot Analysis and included mitochondrial enzymes: ATP synthase, long-chain acyl-CoA dehydrogenase, creatine kinase, malate dehydrogenase, and pyruvate dehydrogenase. The abundance of NAD-dependent deacetylase sirtuin-3 (Sirt3), a mitochondrial deacetylase was reduced in SS and SHHF failing hearts. This is the first description of non-histone protein acetylations associated with heart failure and raises the prospect that acetylations of mitochondrial proteins linked to reduced Sirt3 mediate, in part, metabolic changes in heart failure.
Response from the exposed intracranial human auditory nerve to low-frequency tones: Basic characteristics

The responses recorded from the exposed intracranial portion of the eighth nerve in man with normal hearing to short bursts of low-frequency tones (500, 1000, and 1500 Hz) consist of two components; these two components can be separated by adding and subtracting, respectively, the responses to tonebursts of opposite polarity. Subtracting the responses to tones of opposite polarity reveals a waveform that resembles the sinusoidal waveform of the stimulus (frequency-following response = FFR), while adding the responses to tones of opposite polarity reveals a slow component, the waveform of which is more variable than the frequency-following component. The initial deflection of the slow component of the response to 1000 Hz and to 1500 Hz is a positive peak followed by a slow, negative deflection, and the response to 1500-Hz tonebursts often shows a clear off-response. The slow component of the response to 500-Hz tones often has an initial negative peak followed by a slow, positive or negative wave. The temporal relationship between the stimulus tone and the frequency-following component changes only slightly when the intensity of the sound is changed, whereas the latency of the slow potential decreases with increasing stimulus intensity. The FFR can be masked by noise, and the results of masking with highpass-filtered noise indicate that the frequency-following response may be generated at a location on the basilar membrane that is tuned to a frequency that is higher than that of the stimulus tone.
Selective extraction of Pb2+ by metal-sorbing vesicles bearing ionophores of a new class

Abstract Phosphatidylcholine vesicles harboring three novel ionophores, based on the condensation of Kemp's triacid with aromatic diamine spacers, rapidly and selectively extract Pb2+ from 5 ppm aqueous solutions. Encapsulated nitrilotriacetate, a strong water-soluble chelating agent, provides the driving force for divalent metal ion uptake. At acidic to neutral pH, these metal-sorbing vesicles exhibit more than 100-fold greater initial permeability to Pb2+ than to Cd2+. In competitive metal ion uptake studies, Zn2+ and Cu2+ were taken up more readily than Cd2+, although more slowly than Pb2+. The measured initial permeabilities for these systems containing the synthetic carriers were similar to those for vesicles containing the natural ionophore, A23187, yet showed much greater selectivity for Pb2+ over Cd2+. The selectivity of metal-sorbing vesicles is determined by the complex interplay of the metal ion binding and transport characteristics of the ionophore as influenced by the vesicle bilayer microenvironment as well as encapsulated chelator binding.
Comparison of the microsatellite instability analysis system and the Bethesda panel for the determination of microsatellite instability in colorectal cancers

Microsatellite instability (MSI) analysis of colorectal cancers is clinically useful to identify patients with hereditary nonpolyposis colorectal cancer (HNPCC) caused by germline mutations of mismatch repair genes. MSI status may also predict cancer response/resistance to certain chemotherapies. We evaluated the MSI Analysis System (Promega Corp.; five mononucleotide and two pentanucleotide repeats) and compared the results to the Bethesda panel, which interrogates five microsatellite loci recommended by the 1997 National Cancer Institute-sponsored MSI workshop (three dinucleotide and two mononucleotide repeats). Thirty-four colorectal cancers were analyzed by both assays. The overall concordance between the two assays was 85% (29 of 34). There was complete concordance between the two assays for all of the MSI-high (11 of 11) and microsatellite stable (MSS; 18 of 18) cases. In the 11 MSI-high cases, all 5 of the mononucleotide loci in the MSI Analysis System demonstrated shifted alleles (100% sensitivity), and each shift resulted in products that were smaller in size than the germline alleles. All (5 of 5) of the cases interpreted as MSI-low by the Bethesda assay were interpreted as MSS by the MSI Analysis System. Our results suggest that the MSI Analysis System is generally superior and may help resolve cases of MSI-low into either MSI-high or MSS.
Numerical modelling of water spray barriers for dispersing dense gases

A depth-integrated numerical model is used to calculate the behavior of heavy and cold gas clouds subjected to the diluting influence of a water spray curtain. The model includes the physics of a cold cloud heated by the ground which entrains moist air. Entrainment velocities are influenced by cloud stratification. Laboratory water-curtain trials are predicted accurately. The model reveals the influence of curtain placement, width of spray, spray strength and thermal effects on the efficacy of the water curtain to mitigate potential hazards.
Judicial Mediation: Techniques, Strategies, and Situational Effects

This paper investigates the mediation techniques and strategies used by judges to facilitate the out-of-court settlement of civil cases, and it discusses the circumstances under which judicial mediation is mostly likely to occur. The first of two studies reveals that judges, when using mediation techniques, employ them in three strategies-logical, aggressive, and paternalistic-and that the logical strategy is most effective. Study 2 unearths another strategy-a client-oriented approach-but it does not corroborate the effectiveness findings of Study 1. A final section speculates about the situational factors that influence judicial intervention.
Cardiohepatic and gross pathological changes in rhesus monkeys after intravenous injection of purified cholera enterotoxin.

Abstract Preliminary experiments have been conducted to determine the lethal dose, survival time and cardiohepatic responses to a single i.v. injection of purified cholera enterotoxin in rhesus monkeys. Within 15 min after enterotoxin injection (50 μg/kg), systolic, diastolic and mean blood pressures showed transient increases, followed by sustained decreases throughout the experimental period. The indices of cardiac contractility increased initially and then declined. During an 8-hr period of observation, heart rate, cardiac output and stroke volume increased and liver functions and total peripheral resistance decreased. The survival time ranged from 12·5 to 18 hr in the toxin-inoculated monkeys. Diffuse hemorrhages throughout the body, especially in the cardiac muscle were observed at necropsy. Similar pathologic changes and death were also observed in pigtail and cynomolgus monkeys following an i.v. injection of cholera enterotoxin at the same dose. African green and capuchin monkeys were resistant to i.v. cholera enterotoxin challenge; no clinical illness was shown after a high dose (200 μg/kg) of cholera enterotoxin injection.
Clinical applications with the HIDAC positron camera

Abstract A high density avalanche chamber (HIDAC) positron camera has been used for positron emission tomographic (PET) imaging in three different human studies, including patients presenting with: (I) thyroid diseases (124 cases); (II) clinically suspected malignant tumours of the pharynx or larynx (ENT) region (23 cases); and (III) clinically suspected primary malignant and metastatic tumours of the liver (9 cases, 19 PET scans). The positron emitting radiopharmaceuticals used for the three studies were Na 124 I (4.2 d half-life) for the thyroid, 55 Co-bleomycin (17.5 h half-life) for the ENT-region and 68 Ga-colloid (68 min half-life) for the liver. Tomographic imaging was performed: (I) 24 h after oral Na 124 I administration to the thyroid patients, (II) 18 h after intraveneous administration of 55 Co-bleomycin to the ENT patients and (III) 20 min following the intraveneous injection of 68 Ga-colloid to the liver tumour patients. Three different imaging protocols were used with the HIDAC positron camera to perform appropriate tomographic imaging in each patient study. Promising results were obtained in all three studies, particularly in tomographic thyroid imaging, where a significant clinical contribution is made possible for diagnosis and therapy planning by the PET technique. In the other two PET studies encouraging results were obtained for the detection and precise localisation of malignant tumour disease including an estimate of the functional liver volume based on the reticulo-endothelial-system (RES) of the liver, obtained in vivo, and the three-dimensional display of liver PET data using shaded graphics techniques. The clinical significance of the overall results obtained in both the ENT and the liver PET study, however, is still uncertain and the respective role of PET as a new imaging modality in these applications is not yet clearly established. To appreciate the clinical impact made by PET in liver and ENT malignant tumour staging needs further investigation, and more detailed data on a larger number of clinical and experimental PET scans will be necessary for definitive evaluation. Nevertheless, the HIDAC positron camera may be used for clinical PET imaging in well-defined patient cases, particularly in situations where both high spatial resolution is desired in the reconstructed image of the examined pathological condition and at the same time “static” PET imaging may be adequate, as is the case in thyroid-, ENT- and liver tomographic imaging using the HIDAC positron camera.
Probing the Interface Barriers of Dopant-Segregated Silicide–Si Diodes With Internal Photoemission

An experimental study is presented to probe the interface barriers of dopant-segregated silicide-Si diodes with internal photoemission. The spatial information of the interface dipoles, which is believed to be the cause of the effective Schottky barrier height (SBH) modification, is extracted from the field dependence of the barrier heights. A clear difference between the dopant segregation (DS) junctions and a pure Schottky junction is found: Boron DS modifies the effective SBH by forming a p+- n junction while arsenic DS forms a “Shannon” junction with a fully depleted 1.5-nm doping depth in front of the silicide.
Recent advances in our understanding of hepatitis B infections.

. The development of highly sensitive hemagglutination (HA) assays for detection of hepatitis B antibody has made possible observation of primary anamnestic antibody responses in most individuals exposed to hepatitis B virus and the development and evaluation of a hyperimmune γ-globulin preparation. The hemagglutination inhibition assay, while more sensitive than previous techniques for the detection of hepatitis B antigen (HB-ag) carriers, does not presently appear suitable for use in routine screening of blood donors. However, use of this assay to subtype the antigenic specificities of HB-ag makes it a valuable identity test for ultrasensitive assays. Prospective serologic follow-up of children newly admitted to an institution for the mentally retarded and studies on HB-ag carriers and their families (by hemagglutination inhibition and HA techniques) have revealed that the ratio of infection to clinical disease in hepatitis B infections is greater than 28:1.
Processing of titanium–titanium boride dual matrix composites

Abstract Discontinuously reinforced titanium (Ti)–titanium boride whisker (TiB w ) composites are emerging as strong candidate materials for advanced applications within the automotive, aerospace and defense industries. Although increasing TiB w volume fraction has been shown to significantly improve the specific stiffness and wear resistance of titanium, it is usually on the expense of fracture toughness and ductility especially at high volume fractions of reinforcements. This paper discusses the feasibility of processing Ti–TiB w dual matrix composites that could overcome these shortcomings, by generating composite microstructures consisting of TiB w –Ti composite regions separated by a ductile Ti matrix. This microstructural design has been previously shown to impart unique combinations of properties for other composites. However, the design has never been applied to Ti–TiB w in situ generated composites which require the consideration of new processing steps and the complication of a high-temperature in situ transformation to form TiB w . Two high-temperature powder consolidation methods were investigated (pressure-less sintering and current-activated pressure assisted sintering (CAPAS)). Other aspects investigated include the use of two different boron sources (titanium di-boride (TiB 2 ) and pure boron (B)) in addition to different composite particle sizes. Results show that pressure-less sintering was neither effective at completely forming TiB w , nor generating high-density products. Full conversion to TiB w was however attained using CAPAS generating high-density Ti–TiB w dual matrix composites.
High Power, Tunable, CW, Narrow Line Thulium Fiber Laser for Ranging Applications

We have developed a narrow linewidth (0.3 nm), tunable (1981-2095 nm) Tm fiber-laser for ranging applications with a master oscillator power amplifier with ~100 W configuration. Power scaling to 200 W is underway.
Storage structure and physical data independence

This paper presents the results of an investigation into the feasibility of physical data independence in a data base system. In theory physical data independence may be achieved by providing a picture of the data which remains invariant as the underlying storage structure of the data base changes. In this paper the data picture is assumed to describe the data base as consisting of a set of records in third normal form. The question is, given this third normal form data picture, to what extent may the storage structure change? The paper attempts to answer this question by first defining and explaining a number of concepts, including the important notions of storage equivalence and conformable representation, and then using these concepts to illustrate some possible storage structures for a sample data base. It is demonstrated in particular that the number of possible conformable representations of the data base is potentially very large, and that certain advantages accrue from the choice of a conformable representation. Some non-conformable representations are also shown.This is the second of two associated papers, the first of which deals with the complementary problems of file definition and logical data independence.
Philosophy and psychology at the Sorbonne, 1885–1913.

The first university course in experimental psychology in Paris was located in the Faculty of Letters rather than the Faculty of Sciences or Medecine. The historical association of psychology with philosophy helps explain this placement, but this choise reinforced this philosophical character of the position at the expense of the experimental.
A two-step extraction method for differentiating chromium species in water

The hexavalent Cr species Cr(VI) in natural waters can be quantitatively extracted by diethyldithiocarbamate (DDTC) in the pH range 4.0–4.5 into chloroform, followed by back-extraction into a Hg(II) solution for graphite furnace atomic absorption spectrometry (GFAAS). The trivalent Cr(III) species can be oxidized to Cr(VI) by KMnO4 and then extracted by the DDTC-Hg(II) procedure. The proposed two-step extraction method combined with GFAAS is suitable for Cr speciation studies in natural water systems.
The effects of intervention and social class on children's answers to concrete and abstract questions

Abstract The question/answer format is used as a basic tool by the teacher in communicating information to students and in evaluating their performance. Children from poverty backgrounds have been found to answer questions more poorly than middle-class children and they seem to have particular difficulty with abstract questions. This study was an attempt to understand these social class differences as well as to evaluate whether a preschool intervention program would help poverty children perform better on question answering. The subjects were 88 poverty children (45 had preschool intervention for 5 years and 43 did not). As these children entered kindergarten, 69 comparison children were selected. In the fall of their kindergarten year, two scriptlike stories were read to all children. They were asked to act out each story with props provided, and they were asked a series of concrete and abstract questions about each story. Results indicated that there were no intervention or social class differences in correct answers, but that the children with intervention made less serious errors than children without intervention. It was also found that the question variables were related to important developmental markers of school success for all groups. Implications of this study suggest that the types of response errors children make may be as or more important to understand than whether the answers are right or wrong.
APHANOSPERMA, A NEW GENUS OF ACANTHACEAE FROM MEXICO WITH UNUSUAL DIASPORES'

Recent collections and studies of an unusual species of Acanthaceae from the dry forests of northwestern Mexico reveal it to be generically distinct. Aphanosperma comprises a single species, A. sinaloensis, and is included in the Ruellioideae: Justicieae: Odontoneminae near Carlowrightia. At least four characteristics of the capsule appear to be unique in the family, including progressive reflexing during maturation and permanent retention of the seeds in the capsule valves which thus become the diaspores. The species is shown to be self-compatible and fully autogamous.
Genome-wide comparison of two poplar genotypes with different growth rates

The ecologically dominant and economically important genus Populus, with its available full genome sequence, has become an ideal woody species for genomic study. Rapid growth is one of the primary advantageous features of Populus, and extensive physiological research has been carried out on the growth of Populus throughout the growing period among different clones. However, the molecular information related to the mechanisms of rapid growth is rather limited. In this study, an Affymetrix poplar genome array was employed to analyze the transcriptomic changes from the pre-growth to the fast-growth phase in two poplar clones (P.deltoides × P.nigra, DN2, and P.nigra × (P.deltoides × P. nigra), NE19) with different growth rates. A total of 1,695 differently expressed genes were identified between two time points in NE19 and DN2 (two-way ANOVA, P < 0.01 and fold change ≥2). Except for genes changing in common for both clones, many transcripts were regulated specifically in one genotype. After functional analysis of the differentially expressed genes, distinct biological strategies seemed to be utilized by the two genotypes to accommodate their fast-growth phase. The faster-growing clone NE19, which has a higher photosynthetic rate and larger total leaf area, emphasized growth-related primary metabolism. However, the slower-growing DN2 tended to have more up-regulated genes involved in defense-related secondary metabolism and stress response. Emphasis of such divergent biological processes in two clones may explain their significant growth differences during the fast-growth phase.
Submarine groundwater discharge of rare earth elements to a tidally-mixed estuary in Southern Rhode Island

Abstract Rare earth element (REE) concentrations were analyzed in surface water and submarine groundwater within the Pettaquamscutt Estuary, located on the western edge of Narragansett Bay in Rhode Island. These water samples were collected along the salinity gradient of the estuary. Rare earth element concentrations in the majority of the groundwater samples are substantially higher than their concentrations in the surface waters. In particular, Nd concentrations in groundwater range from 0.43 nmol kg − 1 up to 198 nmol kg − 1 (mean ± SD = 42.1 ± 87.2 nmol kg − 1 ), whereas Nd concentrations range between 259 pmol kg − 1 and 649 pmol kg − 1 (mean ± SD = 421 ± 149 pmol kg − 1 ) in surface waters from the estuary, which is, on average, 100 fold lower than Nd in the groundwaters. Groundwater samples all exhibit broadly similar middle REE (MREE) enriched shale-normalized REE patterns, despite the wide variation in pH of these natural waters (4.87 ≤ pH ≤ 8.13). The similarity of the shale-normalized REE patterns across the observed pH range suggests that weathering of accessory minerals, such as apatite, and/or precipitation of LREE enriched secondary phosphate minerals controls groundwater REE concentrations and fractionation patterns. More specifically, geochemical mixing models suggest that the REE fractionation patterns of the surface waters may be controlled by REE phosphate mineral precipitation during the mixing of groundwater and stream water with incoming water from the Rhode Island Sound. The estimated SGD (Submarine Groundwater Discharge) of Nd to the Pettaquamscutt Estuary is 26 ± 11 mmol Nd day − 1 , which is in reasonable agreement with the Nd flux of the primary surface water source to the estuary, the Gilbert Stuart Stream (i.e., 36 mmol day − 1 ), and of the same order of magnitude for a site in Florida.
Hormone production by cells grown in vitro on artificial capillaries.

Abstract An established human choriocarcinoma cell line has been grown within a perfused artificial capillary bed. Cell densities approaching those of tissue have been attained. Cells maintained in this manner produce human chorionic gonadotropin at rates 11 times higher than those grown in conventional monolayer form.
Evaluation of the ventilatory effects of a restraint chair on human subjects.

Abstract Background: Combative individuals often require physical restraint in the prehospital and law enforcement setting. Specialized restraint chairs have been utilized for this purpose in the latter case, but concern has arisen that restrained individuals are at risk for ventilatory compromise and asphyxiation. Objective: We sought to determine if placement in a restraint chair results in alterations of respiratory or ventilatory function. Methods: We conducted a randomized, cross-over, controlled experimental trial in 10 healthy human volunteers performed at a university exercise physiology laboratory. After exercise on a cycle ergometer to 85% of the age-predicted maximal heart rate, subjects were randomized to either a sitting position or restraint chair with arms, legs, and chest secured using standard law enforcement protocol. Subjects remained in each position for 30 min, during which pulmonary function testing of maximal voluntary ventilation (MVV) was performed at 11 and 30 min. Arterial oxygen saturation (O 2 sat) and end-tidal PCO 2 levels (PETCO 2 ) were monitored continuously. Subjects repeated the experimental trial in the alternate position after a 45-min rest period. Measures between restraint and sitting positions were compared using a paired t -test at each time measurement. Results: There was no evidence of hypoxemia. Mean PETCO 2 levels were not statistically different between the two groups at any time ( p > 0.05), and there was no evidence of hypercapnia. Conclusion: In healthy subjects, placement in a restraint chair resulted in a small decrease in MVV, but did not result in any changes in O 2 sat or PETCO 2 .
Determination of strontium coprecipitated with barium by x-ray emission spectroscopy

Abstract X-Ray emission spectroscopy allows detection of as little as 0.02%, strontium, in barium chromate. This method has been applied to evaluate the effectiveness of 4 procedures for separating barium and strontium by chromate precipitation. All of the procedures checked require at least 2 precipitations for a satisfactory separation. Of the 4 methods checked, that of beyer and rieman is recommended on the basis of convenience and effectiveness of separation.
Astrocyte-Schwann cell interactions in culture

After injury, either as a result of trauma or degenerating/demyelinating diseases, axons of the central nervous system (CNS) normally fail to regenerate. Transplantation of glial cells, particularly Schwann cells, into areas of injury or demyelination has been considered a promising approach to promote recovery. However, the extent of Schwann cell interaction with CNS axons is greatly influenced by the presence of astrocytes which redefine the CNS-PNS (peripheral nervous system) boundary in a lesioned CNS, thereby preventing invasion of Schwann cells. The molecular basis for this restrictive effect of astrocytes on Schwann cells is not known. In the present study, we have cocultured astrocytes and Schwann cells to develop an in vitro model to characterize this interaction. Astrocytes in contact with Schwann cells appeared hypertrophied and showed increased staining for glial fibrillary acidic protein (GFAP). In cocultures maintained for 2-3 weeks, segregation of the two cell types was observed, Schwann cells appeared in groups, and each group was surrounded and separated from one another by astrocytic processes. Since the behavior of these two cell types observed in culture is very similar to their interaction seen in vivo, this coculture model may be useful in further studying the relationship between astrocytes and Schwann cells.
Renal carcinoma after laparoscopic cyst decortication.

A 60-year-old man presented with left flank pain 1 year in duration. Abdominal computerized tomography (CT) and ultrasonography demonstrated a 10 12.5 20 cm. simple cyst in the left kidney (part A of figure). The patient underwent uncomplicated 4 port transperitoneal cyst decortication. Intraoperative examination of the cyst base did not reveal any suspicious areas prior to fulguration. Final pathological evaluation showed the cyst wall was benign. Seven months postoperatively CT for recurrent pain revealed a solid contrast enhancing left renal mass, lymphadenopathy and metastases to the liver and lung (part B of figure). Four subcutaneous nodules were palpable near the port sites. As part of an immunotherapy protocol the left kidney was removed en bloc with the left colon and spleen. Regional lymph nodes and multiple peritoneal lesions were also excised. Pathological examination confirmed chromophil and sarcomatoid renal carcinoma (Fuhrman grade 4) in all specimens, stage pT4N2M1.
Surrogate End Points in Secondary Analyses of Cardiovascular Trials

A surrogate end point is one that is used as a substitute for a clinical end point of more direct interest, usually for reasons of practicality, and that is expected to predict clinical benefit. Surrogate end points play a critical role in the advancement of all medical research, and cardiovascular (CV) research in particular. However, the relationship between a surrogate end point and its clinical end point is usually complex, and there are many examples where results based on surrogates have proved to be misleading. Secondary analyses of existing clinical trial data are likely to involve surrogate end points, if only because clinical end points will have been extensively studied as part of the primary analysis of a trial large enough to collect useful clinical end point data. Validation of a surrogate end point is a laudable goal for a secondary analysis of a large clinical end point trial (or meta-analysis of multiple smaller trials), and the result may be an important new tool for further study of a class of compounds in a particular disease context. Secondary analyses using surrogate end points may also provide new insight into disease or treatment mechanism, but as with any surrogate end point analysis, the results can mislead, and the existing literature is heavy on application and light on methodology. Surrogate end points often substitute efficiency for clarity, and while many interesting and potentially informative secondary analyses of CV trials will involve surrogates, results are likely to be ambiguous and should be interpreted with care.
Electromagnetic granularity, critical current density, and low-Tc phase formation at the grain boundaries in (Bi,Pb)2Sr2Ca2Cu3Oχ silver-sheathed tapes

Abstract Transport critical currents are correlated with DC magnetization, AC susceptibility and high resolution electron microscopy in progressively heat treated Ag-clad (Bi,Pb) 2 Sr 2 Ca 2 Cu 3 O χ (2223) tapes. Both the zero field cooled magnetization shielding curves and the real component of the AC susceptibilities show two diamagnetic transitions. One transition is found to occur at 109 K and is the signature of the 2223 phase. A second, much larger transition occurs over a range of temperatures between 75 and 105 K. The transport critical current densities correlate directly with the lower magnetic transition temperature. High resolution electron microscopy reveals a few layers of Bi 2 Sr 2 CaCu 2 O χ (2212) phase clustered at the numerous (001) twist grain boundaries. These residual layers require a long reaction for their elimination and directly control the critical current while they are present.
The effect of denture cleansers on temporary soft liners

Circular samples of commonly used liners were prepared and immersed in solutions of nine cleansers. Solutions were changed daily for a period of 1 month. Six properties were tested: color change, porosity, surface distortion, size change, water sorption, and solubility. Statistical analysis was applied to measurements to evaluate performance of both cleansers and liners. The results demonstrate that selection of a liner cannot be based on a single property. Changes in resiliency of the liners were not tested in this experiment, but it is recognized that this could be an important factor in liner selection. The liners found to be least affected by the cleansers were Lynal, Tissuedyne, F.I.T.T., and Hydro-Cast, in that order. Viscogel, Softone, and Veltec were most affected. Clorox/Calgon and Miller demonstrated the same overall average performance, tying for first place for four of the liners. Clorox/Calgon was compatible with most liners (six of eight). Mersene and Duo tied for third and fourth places. The thickness of liner materials made little difference on the effects of the cleansers on the properties evaluated.
Psychopathology and its relationship to suicidal ideation in childhood and adolescence.

A sample of 231 children referred for psychiatric treatment were assessed with structured diagnostic instrument, the National Institute of Mental Health Diagnostic Interview Schedule for Children (DISC). A hierarchy of suicidal ideation from nonspecific ideation to suicidal behavior was empirically derived. Both the symptoms and syndrome of depression were correlated with the severity of suicidality, but there was considerable overlap between categories. Parents and their children showed low agreement, but high internal consistency for ratings of suicidality. The continuity between suicidal ideation and suicidal behavior is explored. These findings are compared to those of others in the literature, and implications for further research are discussed.
On the Continuation of Solutions of a Certain Non-linear Differential Equation.

Let p(x) be positive and continuous on [0, oo) and let n be a positive integer; it is known that the differential equation y" + p(x) y~+~ = o, (1) can have solutions defined on a bounded interval which do not admit a~ extension to the interval [0, Go). An example of this singular behavior has been given by Hastings [1], and another example, which is perhaps conceptually somewhat simpler, is given below. In this note we will also establish certain conditions on p(z) which are sufficient to guarantee t ha t all solutions o f (1) can be extended to [0, ~). Two such conditions for a more general equation have been given in [1]. For equation (1) these reduce respectively to the conditions i) that p(x) be piecewise monotone, and ii) that p(x) satisfy a locally uniform Lipschitz condition. The main result of this note states that all solutions of (1) will exist on [0, ~) if p(x) is locally of bounded variation. This condition on p(x) is implied either by condition i) or by condition ii). We remark that piecewise monotonieity is still sufficient if p(x) is only assumed to be non-negative. The proof of our theorem involves the use of a bound for solutions of (1) in terms of the total variation of p(x). Indeed, suppose that :p(x) is of bounded variation on [0, x], with, say, T(x) ~total variation of p(x) on [0, x]. Then, if y(x) is a solution of (1) defined on [0, z0), and if T(x) < m for each x < x0, we have