cssi/SciSciGPT-SciSciNet huggingface dataset:
Homotropic effects in aspartate transcarbamoylase. What happens when the enzyme binds a single molecule of the bisubstrate analog N-phosphonacetyl-L-aspartate?

The active sites of aspartate transcarbamoylase from Escherichia coli were titrated by measuring the decrease in the enzyme-catalyzed arsenolysis of N-carbamoyl-L-aspartate caused by the addition of the tight-binding inhibitor, N-phosphonacetyl-L-aspartate. Because the enzyme is a poor catalyst for this non-physiological reaction, high concentrations are required for the assays (more than 1000-fold the dissociation constant of the reversibly bound inhibitor) and, therefore, virtually all of the bisubstrate analog is bound. From the endpoint of the titration, 5.7 active sites were calculated, in excellent agreement with the number, six, based on the structure of the enzyme. Simple inhibition was observed only when the molar ratio of inhibitor to enzyme exceeded five; under these conditions, as shown in earlier physical chemical studies, the R-conformational state of the enzyme is the sole or predominant species. At low ratios of inhibitor to enzyme, the addition of inhibitor caused an increase in activity which is attributable to the conversion of the enzyme from the low-activity T-state to the much more active R-state. Comparison of the linear increase in activity as a function of inhibitor concentration at the low molar ratio (0.01, i.e. 1 inhibitor/600 active sites) with the activity lost at the high ratio provided a direct value for the mean number of active sites converted from the T-state to the R-state as a result of the binding of one bisubstrate analog to an enzyme molecule. This number was four with Mg X ATP or carbamoyl phosphate present and 4.7 for the enzyme in the presence of Mg X PPi, values approaching or identical to the theoretical maximum, 4.7, for a concerted transition with all of the active sites of the molecule changing from the T- to R-state upon the formation of a binary complex of hexameric enzyme with a single inhibitor. With the enzyme in the absence of effectors or with Mg X CTP present, the titrations showed that an average of two and one sites, respectively, of 4.7 possible, changed conformation upon ligand binding. These results were interpreted as a manifestation of an equilibrium between a sub-population of T- and R-state enzyme complexes containing one bound inhibitor molecule. The R-state species would represent 40% of the population for aspartate transcarbamoylase in the absence of extraneous ligands.(ABSTRACT TRUNCATED AT 400 WORDS)
A Formative Evaluation of the PACT Algebra II Tutor: Support for Simple Hierarchical Reasoning

This paper reports a formative analysis of a principal interface tool in the PACT Algebra II Tutor (PAT2). PAT2 employs modern computational tools to support student reasoning about real-world problem situations. This paper examines a curriculum section on general linear form equations and evaluates the effectiveness of a worksheet tool in reifying the hierarchical structure of the problem situations. Performance analyses suggest that the worksheet effectively supports students in mapping from natural language situations to hierarchical symbolic structures, and that this accounts for the preponderance of observed learning gains. Analyses also suggest that students incur a performance cost in using the worksheet and that the worksheet might be deployed more efficiently in problem solving.
WHO/UNICEF review on complementary feeding and suggestions for future research: WHO/UNICEF guidelines on complementary feeding.

The objectives of this presentation are to: 1. describe briefly the scope and limitations of the recent WHO/UNICEF review of scientific knowledge on complementary feeding of young children in developing countries1 2. review selected conclusions of that document and related recommendations for future research. ### General Comments Before presenting the specific research recommendations, it is worthwhile to note several general issues concerning the WHO/UNICEF review document. First, it must be recognized that this publication was targeted to those aspects of complementary feeding that are particularly relevant for low-income countries. Most infants in these settings are breastfed; and, in general, suitable, low-cost alternatives to breastfeeding are not available. Therefore, no information was provided on feeding non-breastfed infants. Second, because the physiologic and behavioral development and nutritional requirements of infants are in flux, recommendations were prepared for specific categories of infant age. Third, the information included in the report was intentionally directed to a global audience. The document emphasized the need for local adaptation of the conclusions of the report, according to available foods, prevailing feeding practices, economic constraints, and dominant cultural beliefs in particular countries. It was recognized that this local adaptation will require, in some cases, further research on current child feeding practices and the factors that influence them before specific programmatic interventions to improve these practices can be put into place. Finally, the WHO/UNICEF review was oriented to the nutritional needs of generally healthy infants and young children. No information was included on feeding premature infants or children with infections or other acute or chronic diseases that might affect their nutritional status. ### Selected Conclusions of the WHO/UNICEF Report and Recommendations for Research #### Age of Introduction of Complementary Foods The optimal age of introduction of complementary foods remains controversial. The appropriate time may represent a compromise between 2 competing health issues. On one hand, if complementary …
Superposed epoch study of PV5/3 during substorms, pseudobreakups and convection bays

[1] We present a superposed epoch study to examine the entropy parameter PV5/3, for isolated substorms, pseudobreakups and convection bays observed by Geotail in the near-Earth plasma sheet, by using a flux-tube-volume formula with coefficients adjusted to fit magnetic field models for a variety of conditions. It is found that the changes of PV5/3 for these three types of events are distinct: (1) for substorms, PV5/3 increases continuously during the growth phase, decreases after dipolarization, and maintains a low value of ∼0.08 nPa(RE/nT)5/3; (2) for pseudobreakups, PV5/3 changes in a way similar to substorms, but decreases more moderately and then gradually increases; (3) for convection bays, PV5/3 takes a nearly constant value of 0.06 nPa(RE/nT)5/3. These results suggest that the characteristics of the processes that violate conservation of PV5/3 play a central role in the temporal and spatial reduction of PV5/3 and thus determine the earthward plasma transport during active times.
Parallel distributed networks for image smoothing and segmentation in analog VLSI

Consideration is given to switched linear resistive networks and nonlinear resistive networks for image smoothing and segmentation problems in robot vision. The latter network type is derived from the former by way of an intermediate stochastic formulation, and a new result relating the solution sets of the two is given for the so-called zero-temperature limit. The authors present simulation studies of several continuation methods that can be gracefully implemented in analog VLSI and that seem to given good results for these nonconvex optimization problems. >
Late endosomal Rab7 regulates lysosomal trafficking of endocytic but not biosynthetic cargo in Trypanosoma brucei.

Summary We present the first functional analysis of the small GTPase, TbRab7, in Trypanosoma brucei. TbRab7 defines discrete late endosomes closely juxtaposed to the terminal p67+ lysosome. RNAi indicates that TbRab7 is essential in bloodstream trypanosomes. Initial rates of endocytosis were unaffected, but lysosomal delivery of cargo, including tomato lectin (TL) and trypanolytic factor (TLF) were blocked. These accumulate in a dispersed internal compartment of elevated pH, likely derived from the late endosome. Surface binding of TL but not TLF was reduced, suggesting that cellular distribution of flagellar pocket receptors is differentially regulated by TbRab7. TLF activity was reduced approximately threefold confirming that lysosomal delivery is critical for trypanotoxicity. Unexpectedly, delivery of endogenous proteins, p67 and TbCatL, were unaffected indicating that TbRab7 does not regulate biosynthetic lysosomal trafficking. Thus, unlike mammalian cells and yeast, lysosomal trafficking of endocytosed and endogenous proteins occur via different routes and/or are regulated differentially. TbRab7 silencing had no effect on a cryptic default pathway to the lysosome, suggesting that the default lysosomal reporters p67ΔTM, p67ΔCD and VSGΔGPI do not utilize the endocytic pathway as previously proposed. Surprisingly, conditional knockout indicates that TbRab7 may be non-essential in procyclic insect form trypanosomes.
Structural characteristics of human salivary statherin: A model for boundary lubrication at the enamel surface

A three-dimensional structural model for salivary statherin in aqueous phase has been developed using structure prediction, circular dichroism, molecular modeling, and mechanics. The relevant structural features of statherin are N-terminal helix segment connected to a long poly-L-proline type II segment, which is followed by a short extended structure. Using this model, the hydroxyapatite binding ability of statherin has been explained. The hydroxyapatite binding region is comprised of the N-terminal acidic residues (Asp-pSer-pSer-Glu-Glu) and Glu-26, which are clustered together in space. Partial conformational unfolding and oriented aggregation of several statherin molecules at the enamel surface provides an amphipathic film that is responsible for the boundary lubrication exhibited by statherin.
Pharmacokinetics of Fluoride in Man and its Clinical Relevance

A large number of parameters will influence and mediate the activity and the pharmacological response of dental fluoride products after systemic or topical treatment. This report reviews some aspects of the pharmacokinetics of fluoride in man, fluoride bio-availability, plasma kinetics, and kinetics of fluoride in saliva and plaque fluid. Pharmacokinetic studies in growing dogs show that 90% of a single injected fluoride dose is retained shortly after birth, but at maturity it decreases to about 50%. The degree of fluoride accumulating in calcifying tissues seems to be strongly related to age. The bio-availability of fluoride from swallowed fluoride toothpaste is shown to be decreased if the toothpaste is ingested close to a meal. Several studies show that fluoride exerts its cariostatic effects through the liquid phase surrounding the enamel. The importance of fluoride in the fluid environment of the teeth and the kinetics of fluoride in saliva are discussed. Clinical studies using different slow-release fluoride systems indicate that they are promising cariostatic agents--in particular intra-oral slow-release devices and lozenges. A new micro-analytical method to study the kinetics of fluoride in plaque fluid collected from single tooth sites has been developed. Preliminary studies show that the clearance of fluoride from plaque fluid is slowest in the upper incisor region, followed by the molar region, and faster in the lower incisor region. A site-by-site study of the concentration of fluoride in plaque fluid after topical fluoride administration could be extremely beneficial in optimization of the methods and recommended safety regimens for fluoride therapy.
Evaluation of the Drew Scientific ds30 homocysteine assay in comparison with the Centers for Disease Control and prevention reference HPLC method.

Determination of total homocysteine (tHcy) in plasma is becoming an important diagnostic procedure in clinical chemistry because a slightly increased concentration of tHcy in plasma has been discussed as an important independent risk factor for atherosclerotic diseases (1). Many methods, mostly by HPLC, have been reported for measuring tHcy (2). However, these methods are relatively complex and require highly specialized equipment. Drew Scientific, Inc. (company named for identification purposes only; this evaluation does not constitute an endorsement by CDC) has developed the DS30 tHcy system for measuring tHcy in plasma. We evaluated this new system and compared it with our CDC reference HPLC method (3). The DS30 tHcy system comprises a small HPLC system using a 5-cm reversed-phase column, a tHcy assay reagent set that contains the necessary reagents and calibrators [5 and 20 μmol/L homocystine (concentration was equivalent to the free thiol)] and a quality-control (QC) set containing two concentrations of Hcy. The sample preparation requires 200 μL of plasma. A batch of 30 samples can be processed within 90 min. After the addition of 10 μL of the internal standard (IS; 2-mercaptoethylamine) to 200 μL plasma, the mixture of disulfides, mixed disulfides, and protein-bound thiols is reduced using 20 μL of tris(2-carboxyethyl)phosphine (TCEP). Protein is precipitated from this solution with trichloroacetic acid, and 100 μL of the supernatant is then derivatized with a fluorescent thiol-specific dye [ammonium 7-fluorobenzo-2-oxa-1,3-diazole-4-sulfonate (SBDF) in EDTA/borate buffer] at 60 °C for 50 min. The thiol derivatives are separated in a subsequent step by HPLC and detected by their fluorescence. …
Data Structures for Efficient Dynamic Processing in 3-D

This paper considers the problem of the dynamic processing of large amounts of sparse three-dimensional data. It is assumed that computations are performed in a neighborhood defined around each point in order to retrieve local properties. This general kind of processing can be applied to a wide variety of problems. A new, efficient data structure and corresponding algorithms are proposed that significantly improve the speed of the range search operation and that are suitable for on-line operation where data is accumulated dynamically. The method relies on taking advantage of overlapping neighborhoods and the reuse of previously computed data as the algorithm scans each data point. To demonstrate the dynamic capabilities of the data structure, data obtained from a laser radar mounted on a ground mobile robot operating in complex, outdoor environments is used. It is shown that this approach considerably improves the speed of an established 3-D perception processing algorithm.
The Declining Length of Hospitalization for Tubal Sterilization

We analyzed factors affecting the length of hospital stay for tubal sterilization in 1970 and 1975, using data from the National Center for Health Statistic's Hospital Discharge Survey. The average hospital stay for tubal sterilization declined from 6.5 nights in 1970 to 4.0 nights in 1975. Pregnancy status, region of residence, and race were important determinants of the length of hospital stay. One technological innovation, the use of the laparoscope for tubal sterilization, accounted for 39% of the total length-of-stay reduction from 1970 to 1975. General changes in medical care from 1970 to 1975, combined with the introduction of laparoscopy, averted 1,363,000 nights of hospitalization for tubal sterilization in 1975. Conservatively, this resulted in a savings of more than $200 million. About $80 million of this savings was directly attributable to laparoscopy. Even greater savings could have been achieved if sterilization techniques requiring shorter hospital stays had been more widely used. (JAMA1981;245:714-718)
Functional Organization of the Somatosensory Cortical Layer 6 Feedback to the Thalamus

The pathway from cortical layer 6 to the thalamus is a property of all thalamic relay nuclei. This pathway, as a population, directly excites relay cells and indirectly inhibits them via the thalamic reticular nucleus. To understand the circuit organization of this cortical feedback, we used laser-scanning photostimulation, which specifically activates somata or dendrites, to stimulate the primary somatosensory cortex in an in vitro thalamocortical slice preparation while recording from neurons of the ventral posterior medial nucleus. Layer 6 photostimulation evoked biphasic excitatory postsynaptic current/inhibitory postsynaptic current (EPSC/IPSC) responses in the neurons of the ventral posterior medial nucleus, indicating that such photostimulation strongly activates reticular cells. These disynaptic IPSCs were greatly suppressed or abolished by bath application of the muscarinic agonist acetyl-b-methylcholine. Our results suggest that the top-down modulation of thalamic neurons from cortical layer 6 involves an inhibitory component via the thalamic reticular nucleus, and this component can be selectively reduced by cholinergic input. Finally, we found the footprints for the excitatory corticothalamic and the inhibitory corticoreticulo-thalamic inputs to be located in similar positions, though in some cases they are offset. Both patterns have implications for cortico-reticulo-thalamic circuitry.
Plasma Volume Prior to and Following Volume Loading During Shock Complicating Acute Myocardial Infarction

Blood volume was measured following onset of shock in 19 patients who had sustained acute myocardial infarction. The plasma volume was measured by dilution technique utilizing R 125 ISA and the red cell mass by ( 51 Cr) red cell tag, at the time of admission. The plasma volume in six survivors was 41.1 ± 3.3 ml/kg; in 13 fatal cases it was 44.7 ± 4.0 ml/kg; this difference was not significant. The red cell mass in four survivors was 27.2 ± 1.75 ml/kg and in four fatal cases, 24.7 ± 1.60 ml/kg. Since these measurements are within normal ranges, we excluded absolute hypovolemia as a significant factor in accounting for the circulatory failure. Infusion of fluids in amounts which maintained a positive fluid balance selectively increased the plasma volume (57.1 ± 4.4 ml/kg), cardiac index, stroke volume and central blood volume in survivors, and reversed arterial vasoconstriction and lactic acidosis. However, the plasma volume was unaffected in the fatal cases (44.4 ± 4.0 ml/kg) and this was associated with progressive hemodynamic and metabolic deterioration. These observations support the hypothesis that recovery from shock is associated with expansion of plasma volume. To the contrary, during fatal progression of shock, plasma volume expansion does not occur despite volume loading.
CFD Investigation of an Oscillating Structure Placed in a Liquid Medium

Investigation of flow structure in a system comprising of an oscillating structure immersed in a liquid medium has been extensively studied by researchers. Their applications in industrial processing are generally based on the non-linear effects produced by finite amplitude pressure variations created by the oscillating structure. The high frequency oscillations of the structure placed in the liquid medium creates a rapid series of alternating contractions and expansions pressure fields. These amplitudes associated with the high frequency oscillations are accompanied by a series of phenomena such as highly intensified radiation pressure, heat generation, acoustic streaming, agitation, cavitation, interface instabilities and friction, diffusion and mechanical rupture. The high frequency oscillations impart the translation momentum into the liquid during the first half of the cycle and absorb the same in the remainder of the cycle. This paper investigates the cavitation phenomenon, defined as creation of vapor pockets when the liquid pressure falls below the vaporization pressure of the liquid, associated with high frequency oscillations of a structure placed in a liquid medium. This has been performed using CFD analysis of such high frequency oscillations of a structure in a liquid medium using commercially available software. The grids used in the simulations are resolved fine enough to capture the physics of the flow and numerically stabilize the simulation. This transient simulation reveals high pressure gradients close to the oscillating structure due to their rapid motion, which is a function of frequency and amplitude of the vibration. The inception of cavitation phenomenon is associated with highly non-linear vapor bubble dynamics. Discussions on the velocity contours and the distribution of phases in the flow have been carried out in detail with highlights on the bubble dynamics. The use of CFD in simulating fluid structure interaction as in the case above, help us understand the nonlinear effects originating from the generation of high intensity pressure driven fields and their interaction with the medium.Copyright © 2004 by ASME
How stable is the demand for money in emerging economies

One of the key elements of implementing the monetary policy is stability of the demand for money. The literature includes a large number of studies that have tested the stability of the money demand in developed as well as less-developed countries but not in emerging economies of Eastern Europe. As market-based data becomes available from these countries, there is an urgency to test old theories for these modern market-oriented economies. In this article we consider the experiences of Armenia, Bulgaria, the Czech Republic, Hungary, Poland, Russia and the Slovak Republic. Using the bounds testing approach to error-correction modelling and cointegration, we show that money demand is stable in these countries.
Optical bistability in a dissipative thermally expanding etalon

The phenomenon of optical bistability is examined for the case of a lossy Fabry-Perot etalon. Using a multibeam interference method and thermal length expansion relationships, we derive an inverted equation which predicts the output transmission for such an etalon. Specific operating parameters are given for silicon wafer structures operating in the lattice vibration absorption regime (10 μm). Experiments using 15 ms CO 2 laser pulses and Si wafers show resonance-to-nonresonance switching.
The Medication Appropriateness Index at 20: Where It Started, Where It Has Been, and Where It May Be Going

Potentially inappropriate prescribing for older adults is a major public health concern. While there are multiple measures of potentially inappropriate prescribing, the medication appropriateness index (MAI) is one of the most common implicit approaches published in the scientific literature. The objective of this narrative review is to describe findings regarding the MAI’s reliability, comparison of the MAI with other quality measures of potentially inappropriate prescribing, its predictive validity with important health outcomes, and its responsiveness to change within the framework of randomized controlled trials. A search restricted to English-language literature involving humans aged 65+ years from January 1992 to June 2013 was conducted using MEDLINE and EMBASE databases using the search term ‘medication appropriateness index’. A manual search of the reference lists from identified articles and the authors’ article files, book chapters, and recent reviews was conducted to identify additional articles. A total of 26 articles were identified for inclusion in this narrative review. The main findings were that the MAI has acceptable inter- and intra-rater reliability, it more frequently detects potentially inappropriate prescribing than a commonly used set of explicit criteria, it predicts adverse health outcomes, and it is able to demonstrate the positive impact of interventions to improve this public health problem. We conclude that the MAI may serve as a valuable tool for measuring potentially inappropriate prescribing in older adults.
One-dimensional wave pulses in steel-epoxy composites

Experimental studies of wave propagation, attenuation and dispersion have been conducted in order to establish criteria for predicting energy-transfer and absorption properties of uniaxially reinforced steel-epoxy resin composites in the direction of the reinforcement. Laboratory-prepared long-bar specimens were fabricated for test purposes with small-amplitude waves introduced in specimens of varying wire size and volume percent of reinforcement, by impact with pure-epoxy rods projected from an air gun. Impact velocities were sufficiently small that the structural integrity of composite-bar specimens was maintained. Principal results are wave speeds, wave forms, attenuation and dispersion data for several geometries, prediction techniques based on properties of constituent material, and comparisons with wave behavior in the pureconstituent materials.
Energy balance and lactation response in Holstein cows supplemented with cottonseed with or without calcium soap.

Abstract Holstein cows (n = 58, 21 primiparous), fed corn and wilted grass silages (63:37, DM basis) for free choice consumption, were assigned to control concentrate or supplemented concentrate during wk 1 to 16 postpartum with linted whole cottonseed (15% of projected DMI) alone or with Megalac ® (.54 kg/d). Our objective was to examine the effects of fatty acids on energy and N balances, total tract digestibility, and milk fatty acids in wk 7 and 16 and to assess total lactation responses. During balance measurements, fatty acids constituted 4.1, 6.8, and 8.6% of DM in control, oilseed, and oilseed plus protected fatty acid diets. Fat additions reduced fiber digestion (attributed to oilseed) and, to some degree, DMI and milk yield, but enhanced fat test without affecting protein percentage. Supplementary fat increased the proportion of C 18:0 in milk at the expense of short-chain fatty acids. Supplemental oilseed with or without protected fatty acids reduced total heat production by 6% and reduced heat in excess of maintenance by 8%. Best estimates of NE L in linted whole cottonseed and of fat in Megalac ® were 1.81 and 5.69 Mcal/kg of DM. In total lactation, primiparous cows yielded more milk and FCM when fed oilseed plus Megalac ® and less of each when fed oilseed alone than controls. In pluriparous cows, milk yield was reduced by 2.7 kg/d relative to other treatments when oilseed plus Megalac ® was fed; FCM yield increased about 2 kg/d only when oilseed was supplemented alone. Overall, data suggest that basal ration fat and oilseed supplementation were too high or that supplementation should have been delayed until feed intake was higher.
Regional Remodeling of Atherosclerotic Arteries: A Major Determinant of Clinical Manifestations of Disease☆

In this review we present the current data on remodeling, based on in vivo ultrasound imaging or postmortem histologic analysis of native peripheral and coronary arteries from animal models and studies in patients (coronary artery saphenous vein bypass grafts, lesions of restenosis after balloon angioplasty and other catheter-based interventions). Histologic and ultrasound imaging studies of arteries with atherosclerosis and after vascular injury reveal that arterial remodeling is common and that the cross-sectional area of the vessel is not constant. Compensatory enlargement, inadequate compensatory enlargement and shrinkage at the site of atherosclerotic lesions occurs in coronary and peripheral arteries. Current studies demonstrate that arterial remodeling is a major determinant of vessel lumen size.
HeOtx expression in an indirectly developing polychaete correlates with gastrulation by invagination

The expression of an Otx homolog in the indirectly developing polychaete Hydroides elegans was characterized during embryo, trochophore, and feeding-larva stages. In the animal hemisphere, HeOtx is first expressed in 1q(12) blastomeres and their immediate descendants. Such discrete embryonic animal hemisphere Otx expression perhaps relates to cell-type specification functions of the larva. During feeding stages, transcripts are detected in adult cerebral ganglia precursors and putative adult eye precursors, where it may have adult brain regionalization functions. HeOtx is not expressed in primary trochoblast precursors, but it is expressed in cells adjacent to the ciliary band. HeOtx is also expressed in a group of cells in the dorsal midline of the early trochophore larva in putative posterior sensory organ precursors. The vegetal hemisphere expression starts in oral and lateral sides of the blastopore and later expands to central blastomeres that lead the gastrulation movements. During late gastrulation stages, the expression declines in foregut precursors, but it is maintained in midgut precursors, suggesting its involvement in tripartite gut subdivision functions. HeOtx broader and earlier endoderm expression correlates with gastrulation by invagination associated with the formation of the feeding trochophore, in contrast with a later and orally restricted Otx expression found in a polychaete that gastrulates by epiboly and forms a non-feeding trochophore. The endoderm expression and functional roles in other bilaterians suggest an ancestral role of Otx related to gastrulation by invagination.
The Budget Deficit in Transition: A Cautionary Note

This paper discusses major fiscal issues faced by the previously centrally planned economies in their transition to market economies. It focuses on the extent to which the budget deficit should guide policy and the interactions between fiscal policy and other aspects of the macroeconomy.
ac Conductivity of Glasses

We investigate the ac conductivity of glasses due to atomic and electronic hopping between sites with random space and energy separations. Several examples are considered including the structural model of glasses recently introduced by Anderson, Halperin, and Varma, and by Philips. We find that glassy materials should quite generally exhibit a nearly linear conductivity-frequency relationship. The details of any particular conductivity mechanism should be contained in the deviation from linearity.
Scaling vs. Vogel–Fulcher-type structural relaxation in deeply supercooled materials

Abstract A recent scaling-law analysis using τ ∝( T − T c ) − γ with T c T g has concluded that the resulting fits are superior over the Vogel–Fulcher–Tammann temperature dependence as regards the structural relaxation time of supercooled liquids (Colby, Phys. Rev. E 61 (2000) 1783). This issue is investigated based on the dielectric retardation data of poly(vinylacetate) which cover 16 decades in time, from 3 ns to over 1 year. In contrast to Colby's conclusions, the observed temperature dependence rules out a temperature-invariant exponent γ as well as a clear cut critical temperature T c .
Evolution of HLA antigenic determinants: species cross-reactions of monoclonal antibodies.

The reactions of mouse monoclonal HLA-A-, -B-, -C-specific antibodies on cells from 50 species were analyzed by binding assay. Antibodies which are monomorphic in humans generally show monomorphic behavior in other species and many significant cross-reactions were seen. Antibodies which recognize highly specific polymorphic determinants gave few cross-reactions with other species. Antibodies which recognize broad polymorphic determinants in humans cross-reacted in a polymorphic manner with many other species. The patterns of cross-reaction for both monomorphic and broadly polymorphic determinants correlated roughly with the current picture of phylogenetic relationships. These results show there are two fundamentally different classes of polymorphic determinants, one which appears relatively conserved in evolution and one which is the product of recent change. They probably correlate with the public and private antigens of mouse H-2 antigens. A simple genetic model ofHLA-A, -B, -C genes, whereby all specificities at a locus are true alleles, is sufficient to explain these patterns of cross-reaction. It seems likely that cross-reactions previously seen with alloantisera were due to broadly polymorphic antibodies rather than to allele-specific antibodies. If this were the case, then no experimental basis for Bodmer's model of MHC polymorphism being due to control of expression of a tandem array of genes exists.
Fractionation of sulfur isotopes by Desulfovibrio vulgaris mutants lacking hydrogenases or type I tetraheme cytochrome c3

The sulfur isotope effect produced by sulfate reducing microbes is commonly used to trace biogeochemical cycles of sulfur and carbon in aquatic and sedimentary environments. To test the contribution of intracellular coupling between carbon and sulfur metabolisms to the overall magnitude of the sulfur isotope effect, this study compared sulfur isotope fractionations by mutants of Desulfovibrio vulgaris Hildenborough. We tested mutant strains lacking one or two periplasmic (Hyd, Hyn-1, Hyn-2, and Hys) or cytoplasmic hydrogenases (Ech and CooL), and a mutant lacking type I tetraheme cytochrome (TpI- c3 ). In batch culture, wild-type D. vulgaris and its hydrogenase mutants had comparable growth kinetics and produce the same sulfur isotope effects. This is consistent with the reported redundancy of hydrogenases in D. vulgaris . However, the TpI- c3 mutant (ΔcycA) exhibited slower growth and sulfate reduction rates in batch culture, and produced more H2 and an approximately 50% larger sulfur isotope effect, compared to the wild type. The magnitude of sulfur isotope fractionation in the CycA deletion strain, thus, increased due to the disrupted coupling of the carbon oxidation and sulfate reduction pathways. In continuous culture, wild-type D. vulgaris and the CycA mutant produced similar sulfur isotope effects, underscoring the influence of environmental conditions on the relative contribution of hydrogen cycling to the electron transport. The large sulfur isotope effects associated with the non-ideal stoichiometry of sulfate reduction in this study imply that simultaneous fermentation and sulfate reduction may be responsible for some of the large naturally-occurring sulfur isotope effects. Overall, mutant strains provide a powerful tool to test the effect of specific redox proteins and pathways on sulfur isotope fractionation.
Soil and moisture management in Mali: a case study analysis for West Africa

Abstract In order for farmers to accept improved soil and water management practices, new technologies must be appropriate to the specific site conditions found in the farm setting and be consistent with farmers' objectives and available resources. A whole-farm modeling analysis of this problem is described. Preliminary estimates of the benefits of increased soil moisture conservation for representative low-resource farmers in Mali are presented. If farmers could improve rainfall infiltration from currently low rates of about 40% up to 60%, and use small amounts of chemical fertilizers, disposable income could increase two to four times depending on rainfall. Income could be increased another 50% if the infiltration rate was raised to 80%. Food grain production could increase 60 to 90% with improved moisture conservation and fertilizer use.
Reversible on-demand cell alignment using reconfigurable microtopography

Traditional cell culture substrates consist of static, flat surfaces although in vivo, cells exist on various dynamic topographies. We report development of a reconfigurable microtopographical system compatible with cell culture that is comprised of reversible wavy microfeatures on poly(dimethylsiloxane). Robust reversibility of the wavy micropattern is induced on the cell culture customized substrate by first plasma oxidizing the substrate to create a thin, brittle film on the surface and then applying and releasing compressive strain, to introduce and remove the microfeatures, respectively. The reversible topography was able to align, unalign, and realign C2C12 myogenic cell line cells repeatedly on the same substrate within 24 h intervals, and did not inhibit cell differentiation. The flexibility and simplicity of the materials and methods presented here provide a broadly applicable capability by which to investigate and compare dynamic cellular processes not yet easily studied using conventional in vitro culture substrates.
Imagining Ukraine: Regional Differences and the Emergence of an Integrated State Identity, 1926–1994

. When Ukraine gained its independence in 1991, it did not possess an integrated Ukrainian state identity. Serious differences between those regions which entered the Russian empire and the Soviet Union before 1939 and those annexed since 1939 hampered the creation of a post-Soviet state identity. Just as the Ukrainian and Russian languages dominate in different regions in Ukraine, attitudes towards economic reform also vary by region. Russian-speaking areas are more conservative in regard to economic reforms than Ukrainian-speaking ones. But despite these regional differences, Ukraine is not on the verge of civil war. Two public opinion polls taken in 1991 and 1994 in Lviv (in Western Ukraine) and in Donetsk (in Eastern Ukraine) document that the citizens of Ukraine possess a common desire for peace and stability. This desire overshadows Ukraine's regional differences and will help create the new post-Soviet Ukrainian state identity.
Regulating transgenic crops: a comparative analysis of different regulatory processes.

Transgenic crops have the potential to benefit both developed and developing countries. To ensure safe crops to humans and the environment, a strong, but not stifling, regulatory system needs to be established and properly implemented. This paper explores some essential components of a strong regulatory structure for transgenic crops. First, five different regulatory systems for transgenic crops – the United States, the European Union, South Africa, Taiwan, and Argentina – are described and explained. The major components of those systems are then compared to components necessary to a regulatory system that ensures safe products and engenders public trust. The key components discussed include: (1) mandatory pre-market approval; (2) established safety standards; (3) transparency; (4) public participation; (5) use of outside scientists for expert scientific advice; (6) independent agency decisions; (7) post-approval activities; and (8) enforcement authority and resources. Although no one of the existing systems analyzed adequately achieves all the necessary components of a strong regulatory system, those systems serve as models for deciding which regulatory procedures should be emulated and which should be avoided. A mandatory pre-market approval system that applies established safety standards in procedures that are transparent and allows for public participation with no pre-conceived notions or biases will best achieve both safe products and consumer trust.
NEW STUDY AND APPLICATION OF PHASE CONJUGATION WITH PHOTOREFRACTIVE CRYSTALS

A theoretical and experimental study of four-wave mixing in photorefractive crystals like SBN and BaTiO₃ will be presented. A detailed theoretical analysis of the beam coupling as well as new experiments and applications will be described through a distortion ; among them, oneway optical field imaging, a passive (no external pumps) phase conjugate mirror which is pumped by the signal and its use in a laser resonator.
Phenotype of the fibroblast growth factor receptor 2 Ser351Cys mutation: Pfeiffer syndrome type III

We present a patient with pansynostosis, hydrocephalus, seizures, extreme proptosis with luxation of the eyes out of the lids, apnea and airway obstruction, intestinal non-rotation, and severe developmental delay. His skeletal abnormalities include bilateral elbow ankylosis, radial head dislocation, and unilateral broad and deviated first toe. The phenotype of this patient is consistent with that previously reported in Pfeiffer syndrome type III, but is unusual for the lack of broad thumbs. Our patient most closely resembles the case described by Kerr et al. [1996: Am J Med Genet 66:138-143] as Pfeiffer syndrome type III with normal thumbs. Mutations in the genes for fibroblast growth factor receptors (FGFR) 1 and 2 have previously been seen in patients with Pfeiffer syndrome type I. The mutation identified in our patient, Ser351Cys in FGFR2, represents the first reported cause of Pfeiffer syndrome type III. An identical mutation was described once previously by Pulleyn et al., in a patient whose brief clinical description included cloverleaf skull, significant developmental delay, and normal hands and feet [Eur. J. Hum. Genet. 4: 283-291, 1996]. In our patient, previously performed single-strand conformation polymorphism analysis failed to detect a band shift; the mutation was identified only after independent sequence analysis.
Delay Tolerant Networking for free-space optical communication systems

Free-space optical communication (FSOC) systems will be an important part of future networking infrastructures. With the growth in demand from users - both commercial and military - and the scarcity of available RF spectrum, FSOC has the potential to offer a solution. FSOC capacity can easily reach 10psilas Gbps or more over useful ranges. However, the ability to construct an FSOC network has many challenges such as pointing, acquisition and tracking; propagation impairments like weather; eye safety and others. In many of these cases, this will result in an intermittently-connected network, though of tremendous capacity on a per-link basis. This paper examines the applicability of delay tolerant networking (DTN) approaches to such networks and proposes a new routing algorithm that is tailored for the FSOC network characteristics.
G2 inferior vena cava filter: retrievability and safety.

Purpose To assess the retrievability of the G2 inferior vena cava (IVC) filter and factors influencing the safety and technical success of retrieval. Materials and Methods From October 2006 through June 2008, G2 IVC filters were placed in 140 consecutive patients who needed prophylaxis against pulmonary embolism (PE). General indications for filter placement included history of thromboembolic disease ( n = 98) and high risk for PE ( n = 42); specific indications included contraindication to anticoagulation ( n = 120), prophylaxis in addition to anticoagulation ( n = 16), and failure of anticoagulation ( n = 4). Filter dwell time, technical success of filter retrieval, and complications related to placement or retrieval were retrospectively evaluated in patients who underwent filter removal. Results Twenty-seven attempts at G2 filter removal were made in 26 patients (12 men; age range, 24–88 years; mean age, 55.4 y) after a mean period of 122 days (range, 11–260 d). Data were collected retrospectively with institutional review board approval. Filter removal was successful in all 27 attempts (100%). Tilting of the filter (≥15°) occurred in five cases (18.5%), with probable filter incorporation into the right lateral wall of the IVC in one. Other complications of retrieval such as filter thrombosis, significant filter migration, filter fracture, and caval occlusion were not observed. Conclusions G2 IVC filter retrieval has a high technical success rate and a low complication rate. Technical success appears to be unaffected by the dwell time within the reported range.
Experimental observations of wall plasma during a 1-microsecond long relativistic electron beam pulse

Experimental observation of wall plasma produced by a relativistic electron beam propagating through a 2.2 cm diameter stainless steel or copper plated stainless steel drift tube has been made at background pressures as low as 3 X 10-6 Torr. An annular electron beam of thickness approximately 1 mm and outer diameter of approximately 1.8 cm was generated using a carbon fiber or graphite cathode and guided down the drift tube by a 15 kG magnetic field. The electron beam energy varied between 500 to 630 kV with total beam currents between 1 to 2 kA and pulse duration of approximately 750 ns. Two viewing ports and lens systems placed approximately 35 cm apart were used to collect light from plasma produced in the drift tube. The light was transmitted to two SPEX 1702/04 monochrometers using quartz optical fibers. Detection was done with photomultiplier tubes sensitive from 300 to 700 nm and lines from hydrogen, oxygen, iron and copper were observed. At the lowest background pressures no light emission was observed until approximately 1.5 microsecond(s) after the beam pulse for the unheated stainless steel drift tube. After baking and pumping the tube for two days light emission was observed approximately 1.8 microsecond(s) after the start of the beam pulse.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
Endoscopic division of the ary-epiglottic folds in severe laryngomalacia.

Objective: Laryngomalacia is the commonest cause of congenital stridor. The underlying anatomical abnormality associated with this condition is a prolapse of the supraglottic tissues into the laryngeal inlet during inspiration, and may involve the epiglottis, ary-epiglottic folds and the corniculate mounds of the arytenoids. However, it has been noted that the most consistent structural abnormality seen in these cases is the shortening of the ary-epiglottic folds and marked side to side curling of the epiglottis. We describe the follow-up and outcome of 33 cases treated by the simple division of the ary-epiglottic folds. Method: All case notes were reviewed with respect to indications of operation, age of operation, endoscopic findings, operative technique, complications and follow-up until resolution of symptoms. Results: Surgical outcomes could only be ascertained in only 32 patients. Twenty-two cases (68.7%) showed complete resolution of stridor and associated complications of laryngomalacia. In the remaining ten cases who could be followed up (31.2%), seven patients (21.8%) showed partial resolution with no further surgery required, two patients (6.2%) required additional excision of redundant mucosa as second procedure, one patient (3%) with associated cleft lip/palate and tracheomalacia had to undergo a tracheostomy. There was improvement in feeding after surgery in all the 12 patients (100%) who had had pre-operative feeding difficulties. All the four patients with cyanosis pre-operatively were cured, but one of the two patients with apnoeic episodes pre-operatively continued to have apnoeic spells despite resolution of their laryngomalacia. Conclusion: Simple endoscopic excision of the ary-epiglottic folds is a quick, reliable, highly effective procedure with very few complications. We recommend its use as the first line option in the management of severe laryngomalacia, with more extensive methods reserved for the very occasional case of primary failure.
Multiple membrane cavity optomechanics

We investigate theoretically the extension of cavity optomechanics to multiple membrane systems. We describe the simplest case of two membranes in a cavity, in terms of the coupling of the light fields to the breathing and center-of-mass modes of the membrane array. We show that these normal modes can be optically addressed individually and also be cooled, trapped, and characterized, e.g., via quantum nondemolition measurements. The extension to a larger number of membranes is briefly discussed.