cssi/SciSciGPT-SciSciNet huggingface dataset:
Advances in Gene Therapy Using Factor VIIa in Hemophilia

The development of recombinant activated factor VII (rFVIIa; NovoSeven ® , Novo Nordisk, Bagsvaerd, Denmark) has provided an effective, alternative treatment strategy for hemophilia patients with inhibitors. However, its short half-life necessitates frequent infusions and results in high treatment costs. One potential solution to this problem may lie in the use of FVIIa gene transfer, which would achieve long-lasting therapeutic levels of expression from a single injection. Studies in animal models have shown that a recombinant adeno-associated viral vector can be used to insert both murine and human FVIIa into murine liver. Following FVIIa gene transfer, mice with hemophilia B demonstrated a long-term, dose-dependent increase in circulating levels of FVIIa, reduced prothrombin time, and correction of activated partial thromboplastin time into the normal range. In addition, blood loss following a modified tail-clip assay was significantly reduced. Ongoing studies in mice engineered to express a wide range of FVIIa levels aim to analyze organ histology and evaluate long-term survival, reproductive fitness, and real-time in vivo clot formation in the microvasculature. These studies are expanding our knowledge of the effects of continuously expressed rFVIIa, and it is hoped that they may eventually provide a new avenue for treatment of hemophilia.
A logical characterization of iterated admissibility

Brandenburger, Friedenberg, and Keisler provide an epistemic characterization of iterated admissibility (i.e., iterated deletion of weakly dominated strategies) where uncertainty is represented using LPSs (lexicographic probability sequences). Their characterization holds in a rich structure called a complete structure, where all types are possible. Here, a logical characterization of iterated admissibility is given that involves only standard probability and holds in all structures, not just complete structures. Roughly speaking, our characterization shows that iterated admissibility captures the intuition that "all the agent knows" is that agents satisfy the appropriate rationality assumptions.
Enantioselective silver-catalyzed propargylation of imines

A catalytic enantioselective method for the propargylation of aldimines is described. A silver catalyst ligated by a bidentate phoshpine is utilized to provide good yields and high ee's for a variety of substrates. Homopropargylic sulfonamide products undergo facile silver-mediated cyclization to generate 2-pyrrolines, useful intermediates for alkaloid synthesis.
2H-NMR in liquid crystals and membranes

Abstract Deuterium NMR spectroscopy is widely applicable to studies of the structure and dynamics of molecular solids, liquid crystals, and thin films of membrane lipids. The properties of soft nanomaterials are also accessible on the mesoscopic length scale intermediate between the molecular and bulk dimensions. For membrane lipids in the liquid-crystalline state, rapid axial averaging occurs about the director axis (the membrane normal). One can then relate the profiles of the order parameters | S CD | of the individual C– 2 H labeled segments to average bilayer properties. These include the mean area per molecule and projected acyl chain length, the area compressibility modulus, and the radius of curvature for reverse hexagonal ( H II ) phase nanotubes. In addition, measurements of the relaxation rates for Zeeman order, R 1Z , and quadrupolar order, R 1Q , enable one to investigate the mean-squared amplitudes and time-scales of the fluctuations that underlie the thermodynamic properties. A unified interpretation is provided by a composite membrane deformation model, which fits simultaneously the frequency dependence and the angular anisotropy of the R 1Z and R 1Q relaxation rates. The results suggest the bilayer dynamics in the MHz regime can be modeled in terms of nematic-like deformations of the membrane hydrocarbon interior, together with axial rotations of the lipid acyl chains. A small contribution from internal segmental motions is found, which implies the bilayer microviscosity is comparable to that of a liquid hydrocarbon. Finally, the 2 H-NMR relaxation rates of lipid bilayers containing cholesterol in the liquid-ordered phase suggest a dynamically more rigid bilayer, involving fast axial lipid rotations together with a reduction in collective bilayer deformations. Possible future applications include studies of liquid crystals and thin films of membrane lipids and surfactants, as well as lipid-protein systems.
Estradiol-Treated Mesenchymal Stem Cells Improve Myocardial Recovery After Ischemia

Background Stem cell therapy is a promising treatment modality for injured cardiac tissue. A novel mechanism for this cardioprotection may include paracrine actions. Our lab has recently shown that gender differences exist in mesenchymal stem cell (MSC) paracrine function. Estrogen is implicated in the cardioprotection found in females. It remains unknown whether 17β-estradiol (E2) affects MSC paracrine function and whether E2-treated MSCs may better protect injured cardiac tissue. We hypothesize that E2-exposed MSCs infused into hearts prior to ischemia may demonstrate increased vascular endothelial growth factor (VEGF) production and greater protection of myocardial function compared to untreated MSCs. Materials and methods Untreated and E2-treated MSCs were isolated, cultured, and plated and supernatants were harvested for VEGF assay (enzyme-linked immunosorbent assay). Adult male Sprague-Dawley rat hearts (n = 13) were isolated and perfused via Langendorff model and subjected to 15 min equilibration, 25 min warm global ischemia, and 40 min reperfusion. Hearts were randomly assigned to perfusate vehicle, untreated male MSC, or E2-treated male MSC. Transcoronary delivery of 1 million MSCs was performed immediately prior to ischemia in experimental hearts. Results E2-treated MSCs provoked significantly more VEGF production than untreated MSCs (933.2 ± 64.9 versus 595.8 ± 10.7 pg/mL). Postischemic recovery of left ventricular developed pressure was significantly greater in hearts infused with E2-treated MSCs (66.9 ± 3.3%) than untreated MSCs (48.7 ± 3.7%) and vehicle (28.9 ± 4.6%) at end reperfusion. There was also greater recovery of the end diastolic pressure with E2-treated MSCs than untreated MSCs and vehicle. Conclusions Preischemic infusion of MSCs protects myocardial function and viability. E2-treated MSCs may enhance this paracrine protection, which suggests that ex vivo modification of MSCs may improve therapeutic outcome.
Redox flow cell energy storage systems

NASA-Redox systems are electrochemical storage devices that use two fully soluble Redox couples, anode and cathode fluids, as active electrode materials separated by a highly selective ion exchange membrane. The reactants are contained in large storage tanks and pumped through a stack of Redox flow cells where the electrochemical reactions (reduction and oxidation) take place at porous carbon felt electrodes. A string or stack of these power producing cells is connected in series in a bipolar manner. Redox energy storage systems promise to be inexpensive and possess many features that provide for flexible design, long life, high reliability and minimal operation and maintenance costs. These features include independent sizing of power and storage capacity requirements and inclusion within the cell stack of a cell that monitors the state of charge of the system as a whole, and a rebalance cell which permits continuous correction to be made for minor side reactions that would tend to result in the anode fluid and cathode fluids becoming electrochemically out of balance. These system features are described and discussed.
Electronic energy level structure of Tb3+ in LiYF4

We report the experimental results and theoretical modeling for the electronic energy level structure of Tb3+ in laser crystal LiYF4. Using polarized one- and two-photon spectroscopic methods, crystal field levels of the Tb3+ ion have been obtained from the ground multiplet up to 42 000 cm−1 and unambiguously identified. The observed spectra have been analyzed using an effective operator Hamiltonian. Free-ion and crystal field parameters were determined in non-linear least-squares fitting of the calculated energy states to 165 observed levels. Excellent correlation (rms=9.7 cm−1) was obtained between the experiments and the computed energy level structure.
Cosmological Mestel Disks and the Rossby Vortex Instability: The Origin of Supermassive Black Holes

A scenario is put forth for the formation of supermassive black holes at the centers of galaxies. It depends uon the formation of a Mestel disk with a flat rotation curve, M<r ∝ r and Σ ∝ 1/r. Such disks could form from the collapse of uniformly rotating, isolated, gaseous clouds, either protogalactic, galaxy-mass damped Lyα clouds or the gas that survives galaxy mergers. We propose that in either case the disk will be unstable to the Rossby vortex instability (RVI). This instability grows from any large, steep pressure gradient in an optically thick disk. Such pressure gradients either occur adjacent to compact objects or could be triggered by heating from individual supernovae in and around the disk. Upon excitation, the RVI transports angular momentum outward, accreting nearly all mass within the initiation radius. We have calculated that in very thin disks, the nonlinear vortices initiated by the RVI can transport angular momentum far more efficiently than turbulence. Compared to a viscosity-based Shakura-Sunyaev disk, the RVI transports angular momentum out to a much larger radius, so more mass is accreted into the central black hole. A typical galaxy rotational velocity is vrot = 200 km s-1, and the critical column density, necessary to initiate the RVI, is ΣCCD 100 g cm-2. For M<r = 2πr2Σ, we have rCCD = v/(2πΣCCDG), and the mass accreted becomes MBH = v/(2πΣCCDG2) = 3 × 107 M☉. Both the black hole mass MBH and its v dependence are in good agreement with recent observations, because vrot = σc, where σc is the velocity dispersion of the bulge at the radius of mutual contact.
Exponential Convergence to Non-Equilibrium Stationary States in Classical Statistical Mechanics

We continue the study of a model for heat conduction [6] consisting of a chain of non-linear oscillators coupled to two Hamiltonian heat reservoirs at different temperatures. We establish existence of a Liapunov function for the chain dynamics and use it to show exponentially fast convergence of the dynamics to a unique stationary state. Ingredients of the proof are the reduction of the infinite dimensional dynamics to a finite-dimensional stochastic process as well as a bound on the propagation of energy in chains of anharmonic oscillators.
Climate Feedbacks and Their Implications for Poleward Energy Flux Changes in a Warming Climate

AbstractFeedbacks determine the efficiency with which the climate system comes back into equilibrium in response to a radiative perturbation. Although feedbacks are integrated quantities, the processes from which they arise have rich spatial structures that alter the distribution of top of atmosphere (TOA) net radiation. Here, the authors investigate the implications of the structure of climate feedbacks for the change in poleward energy transport as the planet warms over the twenty-first century in a suite of GCMs. Using radiative kernels that describe the TOA radiative response to small perturbations in temperature, water vapor, and surface albedo, the change in poleward energy flux is partitioned into the individual feedbacks that cause it.This study finds that latitudinal gradients in the sum of climate feedbacks reinforce the preexisting latitudinal gradient in TOA net radiation, requiring that the climate system transport more energy to the poles on a warming planet. This is primarily due to structu...
The Moduli Space of Complete Embedded Constant Mean Curvature Surfaces

We examine the space of finite topology surfaces in ℝ3 which are complete, properly embedded and have nonzero constant mean curvature. These surfaces are noncompact provided we exclude the case of the round sphere. We prove that the spaceMk of all such surfaces withk ends (where surfaces are identified if they differ by an isometry of ℝ3) is locally a real analytic variety. When the linearization of the quasilinear elliptic equation specifying mean curvature equal to one has noL2-nullspace, we prove thatMk is locally the quotient of a real analytic manifold of dimension 3k−6 by a finite group (i.e. a real analytic orbifold), fork ≥ 3. This finite group is the isotropy subgroup of the surface in the group of Euclidean motions. It is of interest to note that the dimension ofMk is independent of the genus of the underlying punctured Riemann surface to which Σ is conformally equivalent. These results also apply to hypersurfaces of Hn+1 with nonzero constant mean curvature greater than that of a horosphere and whose ends are cylindrically bounded.
The D1/D5 System And Singular CFT

We study the conformal field theory of the D1/D5 system compactified on X (X is T4 or K3). It is described by a sigma model whose target space is the moduli space of instantons on X. For values of the parameters where the branes can separate, the spectrum of dimensions in the conformal field theory exhibits a continuum above a gap. This continuum leads to a pathology of the conformal field theory, which explains a variety of problems in various systems. In particular, we explain the apparent discrepancy between different methods of finding the spectrum of chiral fields at certain points in the moduli space of the system.
Collusion in the U.S. crop insurance program: applied data mining

This paper quantitatively analyzes indicators of Agent (policy seller), Adjuster (indemnity claim adjuster), Producer (policy purchaser/holder) indemnity behavior suggestive of collusion in the United States Department of Agriculture (USDA) Risk Management Agency (RMA) national crop insurance program. According to guidance from the federal law and using six indicator variables of indemnity behavior, those entities equal to or exceeding 150% of the county mean (computed using a simple jackknife procedure) on all entity-relevant indicators were flagged as "anomalous." Log linear analysis was used to test (I) hierarchical node-node arrangements and (2) a non-recursive model of node information sharing. Chi-square distributed deviance statistic identified the optimal log linear model. The results of the applied data mining technique used here suggest that the non-recursive triplet and Agent-producer doublet collusion probabilistically accounts for the greatest proportion of waste, fraud, and abuse in the federal crop insurance program. Triplet and Agent-producer doublets need detailed investigation for possible collusion. Hence, this data mining technique provided a high level of confidence when 24 million records were quantitatively analyzed for possible fraud, waste, or other abuse of the crop insurance program administered by the USDA RMA, and suspect entities reported to USDA. This data mining technique can be applied where vast amounts of data are available to detect patterns of collusion or conspiracy as may be of interest to the criminal justice or intelligence agencies.
A novel hydroxylation of aromatics in a flavin-initiated chain reaction

Abstract In aqueous acidic solutions, the 5-ethyl-3-methyllumiflavinium cation 5 was spontaneously transformed into the dihydroflavin pseudobase radical 6 and the flavosemiquinone 7 . In attacking an aromatic like phenylalanine, 6 was mainly reconverted to 5 which, ultimately, could lead to an anaerobic accumulation of 7 in yields of 95 ± 5%. In the immediate presence of O 2 and/or H 2 O 2 , 7 was rapidly and continuously reoxidized to 5 which, consequently, gave a continued production of 6 increasing the hydroxylating ability of the system. The oxidants also had a second distinct effect in converting an intermediate X in a chain reaction to further increase the yields of hydroxyphenylalanines. As illustrated by the results obtained with O 2 and H 2 O 2 under comparable conditions, the efficiency of this chain reaction proved to be significantly influenced by the nature of the oxidant. These new findings imply that hydroxyl radicals arising in a homolysis of the OO bond in a dihydroflavin hydroperoxide should not be taken for granted as the primary attacking species in the hydroxylation of an aromatic. From a practical point of view it is noticed that the hydroxylating ability of the new flavin / H 2 O 2 system surpasses that of any other known, flavin-free chemical system.
Amorphous thin film diffusion barriers on GaAs and InP

Abstract Thin films amorphous WSi and TiWSi diffusion barriers have been studied on GaAs and InP surfaces for the purpose of establishing their reliability for ohmic contacts and Schottky barriers, particularly under high temperature stress. The amorphous films were formed by a new method in which alternate layers of tungsten or TiW and silicon were sputter deposited to a total thickness of about 1300 A and subsequently annealed near the glass transition temperature Tg(≈500°C). Electron channeling and reflection electron diffraction were used to determine the amorphous nature of the films as deposited and after 4 h anneals near Tg. The as-deposited films had interfacial amorphous regions with compositions determined by interfacial reactions during the sputtering process. As-deposited WSi films showed a weak channeling pattern which came from the unreacted polycrystalline tungsten layers. From Auger electron spectroscopy (AES) sputter profiles, it was concluded that the amorphous regions were at the WSi interfaces which had the required tungsten-to-silicon composition ratio. After annealing at 500 °C for 4 h, the films were completely amorphous with no marked evidence of crystallization, indicating interfacial reactions extended completely into the tungsten layers. High magnification scanning electron microscopy (by a factor of 20 000) examination of the films after annealing revealed smooth and continuous surfaces with no evidence of grain boundaries. Diffusion along grain boundaries between gold and GaAs or InP in these amorphous thin films was thus almost completely eliminated. Interdiffusion of gold in layered structures (e.g. Au/(WSi)/GaAs) was studied by AES sputter profiling techniques. No interdiffusion of gold or GaAs was observed after 16 h anneals at 400 °C. With Au/(WSi)/InP structures, no interdiffusion was observed after 8 h anneals at 450 °C. These results are significant improvements over those for previous polycrystalline diffusion barriers (e.g. TiPt) which degrade after 1 h at 350 °C. Based on the AES sputter profiles, the diffusion coefficients in WSi amorphous thin films were found to be less than 3 × 10−18 cm2 s−1 at 400 °C for gold, gallium and arsenic and less than 6 × 10−18 cm2s−1 at 450 °C for gold, indium and phosphorus.
Free radical reactions for heterocycle synthesis. Part 5: Formation of novel bridged spirolactones by double cyclizations

Abstract Novel bridged spirolactones have been synthesized via double radical cyclization of enol ester radicals.
Does Cool Reperfusion Limit Myocardial Infarction Injury

In this issue of Circulation: Cardiovascular Interventions , a pilot study by Gotberg et al1 deserves notice. It may have major implications for clinicians who deal with myocardial infarction, and it suggests important insights into the poorly understood area of human reperfusion injury. Article see p 400 The investigator team is to be congratulated for successfully surmounting a formidable implementation challenge. Within 30 minutes, they were able to rapidly cool patient body temperatures to an average less than the target temperature of <35°C without allowing the induction of cooling to interfere with or prolong the door-to-balloon time for percutaneous coronary intervention. To put this 30-minute speed of cooling into perspective, a 2010 investigation of human hypothermia from Australia reported a nearly 8-hour time interval to achieve temperatures <34°C in patients with cardiac arrest.2 The Gotberg pilot study goes on to describe a 38% reduction in infarct size and 43% reduction in peak troponin T release for the patients who received cooling before coronary reperfusion versus controls who received standard reperfusion within the same time period. The study raises an important clinical question that we must address: Is cool reperfusion the best reperfusion? An even more crucial scientific question lies just beneath the surface of these data: Does reperfusion injury exist in humans, and if so, does it have any relevance in terms of long-term function or tissue injury? Reperfusion injury remains controversial since its first description in the 1970s when it was observed that reoxygenation of the ischemic perfused isolated heart resulted in a large release of cardiac injury enzymes along with structural cellular damage seen extensively during reperfusion but only very minimally during the preceding ischemia.3,4 The notion of reperfusion injury suggested that some portion of cell death was caused by the conditions of …
Molecular factors of catalytic selectivity

Selectivity, that is, to produce one molecule out of many other thermodynamically feasible product molecules, is the key concept to develop 'clean manufacturing' processes that do not produce byproducts (green chemistry). Small differences in potential energy barriers for elementary reaction steps control which reaction channel is more likely to yield the desired product molecule (selectivity), instead of the overall activation energy for the reaction that controls turnover rates (activity). Recent studies have demonstrated the atomic- or molecular-level tailoring of parameters such as the surface structures of active sites that give rise to nanoparticle size and shape dependence of turnover rates and reaction selectivities. Here, we highlight seven molecular components that influence reaction selectivities. These include: surface structure, adsorbate-induced restructuring, adsorbate mobility, reaction intermediates, surface composition, charge transport, and oxidation states for model metal single crystal and colloid nanoparticle catalysts. We show examples of their functioning and describe in-situ instruments that permit us to investigate their roles in surface reactions.
Crisis Communication, Race, and Natural Disasters

This study compares differences in crisis preparation, information-seeking patterns, and media use on the basis of race in the aftermath of Hurricane Katrina. Surveys are collected from 935 Katrina evacuees relocated in different areas of the United States. Results indicate differences in crisis preparation and information seeking on the basis of race. Results also demonstrate a continued need to create messages encouraging crisis preparation, especially among at-risk subpopulations.
Multithreaded programming in an introduction to operating systems course

This paper presents a way of teaching multithreaded programming as a component in an introduction to operating systems course. Topics include programming assignments, term projects, and experiences. This paper also suggests future work for overcoming a bottleneck that occurs in the current version of this course.
Force and Stability Measurements on Models of Submerged Pipelines

Force and stability measurements on models of submerged pipelines were made to study the effect of currents on pipe anchored just above the ocean floor. Lift, drag, and stability of two parallel pipes, parallel to a flat plane (the sea floor), were measured for simulated ocean currents up to 2 knots at several subcritical, free stream Reynolds numbers. First, a wind tunnel was utilized to find the lift and drag coefficients on two parallel, rigid, cylindrical models. The effects of horizontal spacing, vertical spacing from the ground plane, and orientation angle of the horizontal free stream velocity were observed. Those results were compared to data available for the single and double cylinder cases where the ground plane was absent. Second, a water tow tank was utilized to observe conditions for eddy-shedding induced vibrations for fixed-end, flexible, parallel cylinders. The natural frequencies and buoyancies of these models simulated pipelines of reasonable span clamped to evenly spaced anchor blocks. A numerical example illustrates the use of these data in design problems.
Biaxial Tensile Testing and Constitutive Modeling of Human Supraspinatus Tendon

The heterogeneous composition and mechanical properties of the supraspinatus tendon offer an opportunity for studying the structure-function relationships of fibrous musculoskeletal connective tissues. Previous uniaxial testing has demonstrated a correlation between the collagen fiber angle distribution and tendon mechanics in response to tensile loading both parallel and transverse to the tendon longitudinal axis. However, the planar mechanics of the supraspinatus tendon may be more appropriately characterized through biaxial tensile testing, which avoids the limitation of nonphysiologic traction-free boundary conditions present during uniaxial testing. Combined with a structural constitutive model, biaxial testing can help identify the specific structural mechanisms underlying the tendon's two-dimensional mechanical behavior. Therefore, the objective of this study was to evaluate the contribution of collagen fiber organization to the planar tensile mechanics of the human supraspinatus tendon by fitting biaxial tensile data with a structural constitutive model that incorporates a sample-specific angular distribution of nonlinear fibers. Regional samples were tested under several biaxial boundary conditions while simultaneously measuring the collagen fiber orientations via polarized light imaging. The histograms of fiber angles were fit with a von Mises probability distribution and input into a hyperelastic constitutive model incorporating the contributions of the uncrimped fibers. Samples with a wide fiber angle distribution produced greater transverse stresses than more highly aligned samples. The structural model fit the longitudinal stresses well (median R(2) ≥ 0.96) and was validated by successfully predicting the stress response to a mechanical protocol not used for parameter estimation. The transverse stresses were fit less well with greater errors observed for less aligned samples. Sensitivity analyses and relatively affine fiber kinematics suggest that these errors are not due to inaccuracies in measuring the collagen fiber organization. More likely, additional strain energy terms representing fiber-fiber interactions are necessary to provide a closer approximation of the transverse stresses. Nevertheless, this approach demonstrated that the longitudinal tensile mechanics of the supraspinatus tendon are primarily dependent on the moduli, crimp, and angular distribution of its collagen fibers. These results add to the existing knowledge of structure-function relationships in fibrous musculoskeletal tissue, which is valuable for understanding the etiology of degenerative disease, developing effective tissue engineering design strategies, and predicting outcomes of tissue repair.
The Bieri–Neumann–Strebel Invariants for Graph Groups

Given a finite simplicial graph ${\cal G}$, the graph group $G{\cal G}$" is the group with generators in one-to-one correspondence with the vertices of ${\cal G}$ and with relations stating two generators commute if their associated vertices are adjacent in ${\cal G}$. The Bieri-Neumann-Strebel invariant can be explicitly described in terms of the original graph ${\cal G}$ and hence there is an explicit description of the distribution of finitely generated normal subgroups of $G{\cal G}$ with abelian quotient. We construct Eilenberg-MacLane spaces for graph groups and find partial extensions of this work to the higher dimensional invariants.
Properties of short channel ballistic carbon nanotube transistors with ohmic contacts

We present self-consistent, non-equilibrium Green's function calculations of the characteristics of short channel carbon nanotube transistors, focusing on the regime of ballistic transport with ohmic contacts. We first establish that the band line-up at the contacts is renormalized by charge transfer, leading to Schottky contacts for small diameter nanotubes and ohmic contacts for large diameter nanotubes, in agreement with recent experiments. For short channel ohmic contact devices, source-drain tunnelling and drain-induced barrier lowering significantly impact the current-voltage characteristics. Furthermore, the ON state conductance shows a temperature dependence, even in the absence of phonon scattering or Schottky barriers. This last result also agrees with recently reported experimental measurements.
User-centered push for timely information delivery

Abstract We propose a new model for push technology that focuses on a dynamic user rather than on a dynamic world. In standard models of push, a central service delivers information to a user when information in the world changes, and the type of information delivered depends on general categories of interest often set directly by the user. Under this model, the world is considered to be changing constantly, while the user is considered relatively static. By contrast, our User-Centered Push (UCP) approach tracks user activity to determine when the user's interest changes. Because UCP bases a user's information needs on a dynamic model of user interests, it has a good chance of delivering information to the user that is both timely and relevant. We describe a general architecture for User-Centered Push, and provide details of an example implementation.
Minimizing communication costs in hierarchically-clustered networks of wireless sensors

A multi-hop network of wireless sensors can be used to gather spatio-temporal samples of a physical phenomenon and transmit these samples to a processing center. This paper addresses the important issue of minimizing the number of transmissions required to gather one sample from each sensor. The technique used to minimize communication costs combines analytical results from stochastic geometry with a distributed, randomized algorithm for generating clusters of sensors. The minimum communication energy achieved by this approach is significantly lower than the energy costs incurred in non-clustered networks and in clustered networks produced by such algorithms as the Max-Min d-cluster algorithm.
Fingerprint Scaling Increases the Probability of Identifying Molecules with Similar Activity in Virtual Screening Calculations

Results of systematic virtual screening calculations using a structural key-type fingerprint are reported for compounds belonging to 14 activity classes added to randomly selected synthetic molecules. For each class, a fingerprint profile was calculated to monitor the relative occupancy of fingerprint bit positions. Consensus bit patterns were determined consisting of all bits that were always set on in compounds belonging to a specific activity class. In virtual screening calculations, scale factors were applied to each consensus bit position in fingerprints of query molecules. This technique, called “fingerprint scaling”, effectively increases the weight of consensus bit positions in fingerprint comparisons. Although overall prediction accuracy was satisfactory using unscaled calculations, scaling significantly increased the number of correct predictions but only slightly increased the rate of false positives. These observations suggest that fingerprint scaling is an attractive approach to increase the ...
Bimolecular Coupling Reactions through Oxidatively Generated Aromatic Cations: Scope and Stereocontrol.

Chromenes, isochromenes, and benzoxathioles react with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone to form stable aromatic cations that react with a range of nucleophiles. These oxidative fragment coupling reactions provide rapid access to structurally diverse heterocycles. Conducting the reactions in the presence of a chiral Bronsted acid results in the formation of an asymmetric ion pair that can provide enantiomerically enriched products in a rare example of a stereoselective process resulting from the generation of a chiral electrophile through oxidative carbon–hydrogen bond cleavage.
Au- and pt-catalyzed cycloisomerizations of 1,5-enynes to cyclohexadienes with a broad alkyne scope.

We describe the development of gold- and platinum-catalyzed cycloisomerizations of 1,5-enynes. This catalytic process displays a wide alkyne scope and furnishes a range of highly functionalized 1,4- and 1,3-cyclohexadienes. In the case of 1-siloxy-1-yne-5-enes, the reactions are efficiently catalyzed by AuCl (1 mol %) at ambient temperature to afford siloxy cyclohexadienes or the corresponding 1,2- and 1,3-cyclohexenones upon subsequent protodesilylation. We propose that the reaction proceeds via a novel mechanism involving a series of 1,2-alkyl shifts. Elucidation of this unusual reaction mechanism enabled us, in turn, to significantly expand the scope of the cycloisomerization by incorporation of a quaternary center at the C(3) position of the enyne. Indeed, we established that PtCl2 (5 mol %) efficiently catalyzed the cycloisomerizations of 1,5-enynes containing terminal, internal, and arene-conjugated alkynes. Since a variety of 1,5-enynes are readily accessible, the cycloisomerization provides a rapi...
Dilaton contact terms in the bosonic and heterotic strings

Abstract Dilaton contact terms in the bosonic and heterotic strings are examined following the recent work of Distler and Nelson on the bosonic and semirigid strings. In the bosonic case dilaton two-point functions on the sphere are calculated as a stepping stone to constructing a “good” coordinate family for dilaton calculations on higher genus surfaces. It is found that dilaton-dilaton contact terms are improperly normalized, suggesting that the interpretation of the dilaton as the first variation of string coupling breaks down when other dilatons are present. It seems likely that this can be attributed to the recently found tachyon divergence. For the heterotic case, it is found that there is no tachyon divergence and that the dilaton contact terms are properly normalized. Thus, a dilaton equation analogous to the one in topological gravity is derived and the interpretation of the dilaton as the string coupling constant goes through.
Kinetics of silica deposition from simulated geothermal brines

Supersaturated brines were passed through columns packed with several forms of silica (crystalline ..cap alpha.. quartz, polycrystalline ..cap alpha.. quartz, and porous Vycor). Also, silica deposition on ThO/sub 2/ microspheres and titanium powder was studied under controlled conditions of supersaturation, pH, temperature, and salinity. The residence time was varied by adjustments of flow rate and column length. The silica contents of the input and effluent solutions were determined colorimetrically by a molybdate method which does not include polymers without special pretreatment. Essentially identical deposition behavior was observed once the substrate was thoroughly coated with amorphous silica and the BET surface area of the coated particles was taken into account. The reaction rate is not diffusion limited in the columns. The silica deposition is a function of the monomeric Si(OH)/sub 4/ concentration in the brine. The deposition on all surfaces examined was spontaneously nucleated. The dependence on the supersaturation concentration, hydroxide ion concentration, surface area, temperature and salinity were examined. Fluoride was shown to have no effect at pH 5.94 and low salinity. The empirical rate law which describes the data in 1 m NaCl in the pH range 5-7 and temperatures from 60 to 120/sup 0/C is given.
Radar return from a continuous vegetation canopy

The radar backscatter coefficient \sigma\deg of alfalfa was investigated as a function of both radar parameters and the physical characteristics of the alfalfa canopy. Measurements were acquired with an 8-18 GHz FM-CW mobile radar over an angular range of 0\deg-70\deg as measured from nadir. The experimental data indicate that the excursions of \sigma\deg at nadir cover a range of nearly 18 dB during one complete growing cycle. An empirical model for \sigma\deg was developed, which accounts for its variability in terms of soil moisture, plant moisture, and plant height.
Distinguished conjugacy classes and elliptic Weyl group elements

We define and study a correspondence between the set of distinguished G^0-conjugacy classes in a fixed connected component of a reductive group G (with G^0 almost simple) and the set of (twisted) elliptic conjugacy classes in the Weyl group. We also prove a homogeneity property related to this correspondence.
Synthetic and Mechanistic Studies of Pd-Catalyzed C−H Arylation with Diaryliodonium Salts: Evidence for a Bimetallic High Oxidation State Pd Intermediate

This contribution describes the substrate scope and mechanism of Pd-catalyzed ligand-directed C-H arylation with diaryliodonium salts. This transformation was applied to the synthesis of a variety of different biaryl products, using directing groups including pyridines, quinolines, pyrrolidinones, and oxazolidinones. Electronically and sterically diverse aryl groups (Ar) were transferred in high yield using iodine(III) reagents of general structure [Mes-I-Ar]BF(4). Mechanistic investigations have been conducted that establish the kinetic order of the catalytic reaction in each component, determine the resting state of the catalyst and the iodine(III) reagent, quantify the electronic influence of the arylating reagent on the reaction rate, and establish the intra- and intermolecular 1 degree H/D kinetic isotope effect. On the basis of these studies, this transformation is proposed to proceed via turnover-limiting oxidation of the Pd dimer [Pd(N~C)(OAc)](2) (N~C = 3-methyl-2-phenylpyridine) by [Mes-I-Ph]BF(4). This mechanism implicates a bimetallic high oxidation state Pd species as a key catalytic intermediate. The significance of this and other aspects of the proposed mechanism are discussed in detail.
Hydrogen fluoride vibrational energy distributions for the reactions of fluorine atoms with cyclanes

The hydrogen fluoride infrared chemiluminescence produced by the reactions of fluorine atoms with cyclopropane, cyclopentane, and cyclohexane have been studied. The emission data were used to determine the vibrational energy distributions for the abstraction of hydrogen from the secondary carbon–hydrogen bonds of these small cyclic hydrocarbons. The fraction of reaction exothermicity going into vibrational excitation of hydrogen fluoride was as follows: c-C3H6, 45%; c-C5H10, 53%; c-C6H12, 49%. The slightly lower fraction for the cyclopropane system may indicate that its radical reorganization energy is not completely available for excitation of product HF.
Proton-Catalyzed Hydroamination and Hydroarylation Reactions of Anilines and Alkenes: A Dramatic Effect of Counteranions on Reaction Efficiency

The anilinium salt, [PhNH3][B(C6F5)4], has been identified as a catalyst for the hydroamination and hydroarylation of several different types of alkenes with anilines. The weakly coordinating counterion of this acid plays a key role in this transformation. The reaction is facile for styrenes and tolerates norbornene, cyclic alkenes, and cyclohexadiene. Selectivity between hydroamination and hydroarylation products can be tuned using reaction time, temperature, and substrate substitution. Details regarding the substrate scope and selectivity of this hydroamination/hydroarylation reaction are discussed.
Density Changes in Plutonium Observed from Accelerated Aging using Pu-238 Enrichment

Abstract In support of Stockpile Stewardship activities, accelerated aging tests on a plutonium alloy enriched with 7.3 at.% of 238Pu is underway using dilatometry at 35, 50, and 65 °C and immersion density measurements of materials stored at 50 °C. Changes in density are expected from radiation damage in the lattice and helium in-growth. After 25 equivalent years of aging, the dilatometry data shows that the alloys at 35 °C have expanded in volume by 0.11–0.12% and have started to exhibit a near linear expansion behavior primarily caused by the helium accumulation. The average He-to-vacancy ratio from tested specimens was determined to be around 2.55. The model for the lattice damage and helium in-growth accurately represents the volume swelling at 35 °C. The density converted from the dilatometry corresponds well to the decreasing density trend of reference plutonium alloys as a function of time.
The HERMES experiment

Abstract HERMES, HE RA M easurement of S pin, is an experiment underway at DESY to study the spin structure of the nucleon by using polarized internal gas targets in the HERA 27.5 GeV electron storage ring. Inclusive and semi-inclusive spin dependent deep inelastic scattering are simultaneously measured in a forward spectrometer. In 1995 the experiment was installed and commissioned and data were taken on a polarized 3He target as well as on unpolarized targets of hydrogen and deuterium. In this paper, several aspects of the spin structure of the nucleon which can be probed by HERMES are discussed. The experiment is briefly described and some preliminary results from 1995 running are presented.
MobiNet: a scalable emulation infrastructure for ad hoc and wireless networks

The current state of the art in evaluating applications and communication protocols for ad hoc wireless networks usually involves either simulation or small-scale live deployment. Larger-scale live deployment is typically costly and difficult to run under controlled circumstances. Simulation allows more flexibility in varying system configurations, but requires the duplication of application and network behavior within the simulator. While simulation and live deployment will clearly continue to play important roles in the evaluation of mobile systems, we present MobiNet, a third point in this space. In MobiNet, the communication of unmodified applications running on stock operating systems is subject to the real-time emulation of a user-specified wireless network environment. MobiNet utilizes a cluster of emulator nodes to appropriately delay, drop or deliver packets in a hop by hop fashion based on MAC-layer protocols, ad hoc routing protocols, congestion, queuing, and available bandwidth in the network. Our evaluations show that MobiNet emulation is scalable and accurate while executing real code, including video playback.
Antarctic ice and sediment flux in the Oligocene simulated by a climate–ice sheet–sediment model

Abstract A model of deforming sediment is added to a climate–ice sheet model, and applied to the Eocene–Oligocene transition in Antarctic ice volume around 34 Ma. The coupling between the global climate and ice sheet models is asynchronous, with a climate simulation performed once every 10 000 years, and only for the first 40 000 years. These global climate model solutions are re-used to perform runs of 400 000 years in length, with orbital forcing and different levels of CO2. The sediment model includes bulk transport under ice, generation of sub-ice till, and river transport, and predicts the continental-scale evolution of sediment thickness and coastal discharge. For the first few 10 000’s of years after the onset of substantial ice (triggered by CO2 falling below ∼3× pre-industrial level), sediment discharge to the ocean is relatively uniform around the coast, derived from nearby pre-existing regolith. After that, most discharge is concentrated into ∼4 sites at the mouths of major trough systems, with orbitally paced pulses on 104-yr scales. These sites and the average magnitudes of the fluxes agree generally with those deduced from offshore seismic and core data, although longer (10 my) integrations are needed to model the real sediment evolution.
Computations of supersonic flow over a missile afterbody containing an exhaust jet

Abstract : A thin-layer Navier-Stokes code, developed for projectile aerodynamics, has been used to compute the supersonic flow over a missile afterbody containing a centered exhaust jet. The thin-layer, compressible, Navier-Stokes equations are solved using a time dependent, implicit numerical algorithm. A unique flow field segmentation procedure is used which preserves the sharp base corner and facilitates the adaption of the grid to the free shear layer in the base region. Solutions have been obtained for an axisymmetric, boattailed afterbody where the free stream Mach number is 2.0 and the jet exit Mach number is 2.5. Computations were made at various jet static pressure to free stream static pressure ratios from 1 through 9. Qualitative features of the base region flow field seen experimentally are very well observed in the computed results. Quantitative comparisons of base pressure with experiment indicate good agreement at high pressure ratios and some disagreement at low pressure ratios.
Natural-product-like chiral derivatives by solid-phase synthesis

In this genomics and proteomics age, highly functionalized natural products or natural-product-like compounds are likely to play important roles in understanding the functions of emerging biological targets because they serve as small-molecule chemical probes in modulating a target's specific actions (i.e. activation or deactivation). Development of stereoselective reaction-derived methods on solid phase provides a means of obtaining functionalized chiral core structures that may be used for high-throughout syntheses.
Innovating by accessing knowledge across departments

It is widely believed that individuals are more likely to be innovative if they are exposed to different perspectives and domains. While it is purported that knowledge management systems can help, they have generally failed to do so, because there are significant thought world barriers associated with the different perspectives and domains that individuals have to overcome. Using the theory of thought worlds as a theoretical lens, we examined how innovative engineers successfully accessed knowledge from other functional departments. We found that the way they accessed the knowledge had implications for designing knowledge management technology specifically focused on fostering innovation.
Superconducting ground state of noninteracting particles obeying fractional statistics.

In a previous paper, Kalmeyer and Laughlin argued that the elementary excitations of the original Anderson resonating-valence-bond model might obey fractional statistics. In this paper. it is shown that an ideal gas of such particles is a new kind of superconductor.
Central and peripheral representation of whispered and voiced speech.

Whispered speech is very different acoustically from normally voiced speech, yet listeners appear to have little trouble perceiving whispered speech. Two selective adaptation experiments explored the basis for the common perception of whispered and voiced speech, using two synthetic /ba/-/wa/ continua (one voiced, and one whispered). In the first experiment the endpoints of each series were used as adaptors, along with several nonspeech adaptors. Speech adaptors produced reliable labeling shifts of syllables matching in periodicity (i.e., whispered-whispered or voiced-voiced); somewhat smaller effects were found with mismatched periodicity. A periodic nonspeech tone with short rise time (the "pluck") produced adaptation effects like those for /ba/. These shifts occurred for whispered test syllables as well as voiced ones, indicating a common abstract level of representation for voiced and whispered stimuli. Experiment 2 replicated and extended Experiment 1, using same-ear and cross-ear adaptation conditions. There was perfect cross-ear transfer of the nonspeech adaptation effect, again implicating an abstract level of representation. The results support the existence of two levels of processing for complex acoustic signals. The commonality of whispered and voiced speech arises at the second, abstract level. Both this level, and the earlier, more directly acoustic level, are susceptible to adaptation effects. Language: en