cssi/SciSciGPT-SciSciNet huggingface dataset:
A nutrient combination that can affect synapse formation.

Brain neurons form synapses throughout the life span. This process is initiated by neuronal depolarization, however the numbers of synapses thus formed depend on brain levels of three key nutrients—uridine, the omega-3 fatty acid DHA, and choline. Given together, these nutrients accelerate formation of synaptic membrane, the major component of synapses. In infants, when synaptogenesis is maximal, relatively large amounts of all three nutrients are provided in bioavailable forms (e.g., uridine in the UMP of mothers’ milk and infant formulas). However, in adults the uridine in foods, mostly present at RNA, is not bioavailable, and no food has ever been compelling demonstrated to elevate plasma uridine levels. Moreover, the quantities of DHA and choline in regular foods can be insufficient for raising their blood levels enough to promote optimal synaptogenesis. In Alzheimer’s disease (AD) the need for extra quantities of the three nutrients is enhanced, both because their basal plasma levels may be subnormal (reflecting impaired hepatic synthesis), and because especially high brain levels are needed for correcting the disease-related deficiencies in synaptic membrane and synapses.
The most reliable data-path transmission

This paper examines the problem of transmitting a given amount of data along a single path from a designated source to a designated target in a directed network so that the reliability of the transmission is maximum. In this routing problem, the subpaths of an optimal path are not necessarily optimal. This complicates the process of selecting a path along which the data-transmission is completed in minimum time. A polynomial-time algorithm is presented which guarantees an optimal solution. On acyclic networks with interconnections that operate with the same reliability, another polynomial time algorithm is presented that computes the best route for each possible value of data. This is a useful pre-computation when different amounts of data need to be transmitted at different time periods.
Convection Effects in Three-Dimensional Dendritic Growth

A phase-field model is developed to simulate free dendritic growth coupled with fluid flow for a pure material in three dimensions. The preliminary results presented here illustrate the strong influence of convection on the three-dimensional (3D) dendrite growth morphology. The knowledge of the flow and temperature fields in the melt from the simulations allows for a detailed understanding of the convection effects on dendritic growth.
Gender and Policy Effects on Technology Adoption in Zambia

This paper uses the Double-Hurdle model on panel household data for small scale farmers in Zambia to examine policy gender effects on technology adoption by farmers. Technology adoption in this paper is defined as fertilizer use by small-scale farm households. The paper uses the correlated random effects framework to account for unobserved heterogeneity between farmers and its correlation with explanatory variables used in the Double-Hurdle Model. A control function approach is used to account for potential endogeneity of subsidized input.
Smooth wavelets, transform coding, and Markov-1 processes

This paper compares the energy compacting properties of unitary transforms from transform coders and two-band paraunitary filter banks from subband coders using a cost criterion that is proposed. Stationary processes for which paraunitary filters have better energy compaction than unitary filters are denoted as subband optimal, and all subband optimal processes are analytically characterized for the case of length-4 filters. It is shown analytically for length-4 filters and empirically for longer-length filters that Markov-1 processes are subband optimal and that the Daubechies (1988) maximally smooth wavelet sequences achieve better energy compaction than the best unitary filters for Markov-1 inputs.
On Stability of Randomly Switched Nonlinear Systems

This note is concerned with stability analysis and stabilization of randomly switched systems. These systems may be regarded as piecewise deterministic stochastic systems: the discrete switches are triggered by a stochastic process which is independent of the state of the system, and between two consecutive switching instants the dynamics are deterministic. Our results provide sufficient conditions for almost sure stability and stability in the mean using Lyapunov-based methods when individual subsystems are stable and a certain ldquoslow switchingrdquo condition holds. This slow switching condition takes the form of an asymptotic upper bound on the probability mass function of the number of switches that occur between the initial and current time instants. This condition is shown to hold for switching signals coming from the states of finite-dimensional continuous-time Markov chains; our results, therefore, hold for Markovian jump systems in particular. For systems with control inputs, we provide explicit control schemes for feedback stabilization using the universal formula for stabilization of nonlinear systems.
fRMSDPred: predicting local RMSD between structural fragments using sequence information.

The effectiveness of comparative modeling approaches for protein structure prediction can be substantially improved by incorporating predicted structural information in the initial sequence-structure alignment. Motivated by the approaches used to align protein structures, this article focuses on developing machine learning approaches for estimating the RMSD value of a pair of protein fragments. These estimated fragment-level RMSD values can be used to construct the alignment, assess the quality of an alignment, and identify high-quality alignment segments. We present algorithms to solve this fragment-level RMSD prediction problem using a supervised learning framework based on support vector regression and classification that incorporates protein profiles, predicted secondary structure, effective information encoding schemes, and novel second-order pairwise exponential kernel functions. Our comprehensive empirical study shows superior results compared with the profile-to-profile scoring schemes. We also show that for protein pairs with low sequence similarity (less than 12% sequence identity) these new local structural features alone or in conjunction with profile-based information lead to alignments that are considerably accurate than those obtained by schemes that use only profile and/or predicted secondary structure information. Proteins 2008. © 2008 Wiley-Liss, Inc.
An MPI Implementation of the SPAI Preconditioner on the T3E

The authors describe and test spai_1.1, a parallel MPI implementation of the sparse approximate inverse (SPAI) preconditioner. They show that SPAI can be very effective for solving a set of very large and difficult problems on a Cray T3E. The results clearly show the value of SPAI (and approximate inverse methods in general) as the viable alternative to ILU-type methods when facing very large and difficult problems. The authors strengthen this conclusion by showing that spai_1.1 also has very good scaling behavior.
Interaction between Unstable Optical Resonator and CW Chemical Laser

The primary objective of the study was to determine the effect of the optical resonator magnification and centerline location on the near-field output power from a cw chemical laser. Geometric optics are used. The flowing gain medium is assumed to be adjacent to one of the resonator mirrors. Analytic solutions are obtained in the limits M $Yields$ 1 and M much greater than 1, where M is cavity magnification. Effects of resonator and laser medium parameters on laser output power are then discussed. Turbulent and laminar diffusion is considered. (TFD)
Synthesis of Enantiomerically Pure N-tert-Butanesulfinyl Imines (tert-Butanesulfinimines) by the Direct Condensation of tert-Butanesulfinamide with Aldehydes and Ketones

Experimental details for the first general methods for the one-step preparation of N-tert-butanesulfinyl imines (tert-butanesulfinimines) (2) from aldehydes and ketones is described. To effect the condensations of tert-butanesulfinamide (1) with aldehydes, the Lewis acidic dehydrating agents MgSO4, CuSO4, or Ti(OEt)4 are employed. Aldehyde condensations mediated by MgSO4 proceed in high yields (84−96%) when an excess of aldehyde is used. In contrast, only a slight excess of aldehyde (1.1 equiv) relative to tert-butanesulfinamide provides sulfinimines in high yields when the more Lewis acidic dehydrating agent CuSO4 is used. The CuSO4-mediated procedure is effective for a wide range of aldehydes, including sterically demanding aldehydes, such as isobutyraldehyde (90%), and electron-rich aldehydes, such as p-anisaldehyde (81%). The still more Lewis acidic Ti(OEt)4 and Ti(O-i-Pr)4 also afford N-tert-butanesulfinyl aldimines from especially unreactive aldehydes, such as pivaldehyde (82%). In addition, Ti(OEt)...
School finance, spatial income segregation, and the nature of communities

In a general equilibrium model that links school and housing markets, a purely public school system (regardless of the degree of centralization) results in substantially more spatial income segregation than a purely private system. However, the combination of a public system with a private school market yields the least residential segregation as housing price distortions from the capitalization of the public system generate incentives for middle and high income private school attendees to live with lower income public school attendees. The impact of vouchers and the sensitivity of results to alternative school production models is also investigated.
Optimization of Periodic Composite Structures for Sub-Wavelength Focusing

Recently, there has been plenty of work in designing and fabricating materials with an effective negative refractive index. Veselago realized that a slab of material with a refractive index of −1 would act as a lens. Pendry suggested that the Veselago lens would act as a superlens, providing a perfect image of an object in contrast to conventional lenses which are only able to focus a point source to an image having a diameter of the order of the wavelength of the incident field. Recent work has shown that similar focusing effects can be obtained with certain slabs of “conventional” periodic composite materials: photonic crystals. The present work seeks to answer the question of what periodic dielectric composite medium (described by dielectric coefficient with positive real part) gives an optimal image of a point source. An optimization problem is formulated and it is shown that a solution exists provided the medium has small absorption. Solutions are characterized by an adjoint-state gradient condition, and several numerical examples illustrate both the plausibility of this design approach, and the possibility of obtaining smaller image spot sizes than with typical photonic crystals.
Correct Ordering in the Zipf–Poisson Ensemble

Rankings based on counts are often presented to identify popular items, such as baby names, English words, or Web sites. This article shows that, in some examples, the number of correctly identified items can be very small. We introduce a standard error versus rank plot to diagnose possible misrankings. Then to explain the slowly growing number of correct ranks, we model the entire set of count data via a Zipf–Poisson ensemble with independent Xi ∼ Poi(Ni − α) for α > 1 and N > 0 and integers i ⩾ 1. We show that as N → ∞, the first n′(N) random variables have their proper order relative to each other, with probability tending to 1 for n′ up to (AN/log (N))1/(α + 2) for A = α2(α + 2)/4. We also show that the rate N 1/(α + 2) cannot be achieved. The ordering of the first n′(N) entities does not preclude for some interloping m > n′. However, we show that the first n″ random variables are correctly ordered exclusive of any interlopers, with probability tending to 1 if n″ ⩽ (BN/log (N))1/(α + 2) for any B < A....
Probability, conditional probability and complementary cumulative distribution functions in performance assessment for radioactive waste disposal

Abstract A formal description of the structure of several recent performance assessments (PAs) for the Waste Isolation Pilot Plant (WIPP) is given in terms of the following three components: a probability space ( S st, L st, Pst) for stochastic uncertainty, a probability space ( S su, L su, Psu) for subjective uncertainty and a function (i.e., a random variable) defined on the product space associated with ( S st, L st, Pst) and ( S su, L su, Psu). The explicit recognition of the existence of these three components allows a careful description of the use of probability, conditional probability and complementary cumulative distribution functions within the WIPP PA. This usage is illustrated in the context of the US Environmental Protection Agency's standard for the geologic disposal of radioactive waste (40 CFR 191, Subpart B). The paradigm described in this presentation can also be used to impose a logically consistent structure on PAs for other complex systems.
Reversible in situ catalyst formation.

Acid catalysts play a vital role in the industrial synthesis and production of a plethora of organic chemicals. But, their subsequent neutralization and disposal is also a giant source of waste. For example, for a Friedel−Crafts acylation with AlCl3, a kilogram of product yields up to 20 kg of (contaminated) waste salt. Other processes are even worse, and this waste is both an environmental and economic shortcoming. Here we address this issue by showing a series of acid catalysts where the neutralization is “built in” to the system and thus eliminates waste. Clearly these will not replace all organic and mineral acid catalysts, but they can replace many. Further, we show how these self-neutralizing catalysts can often eliminate unwanted byproducts, improve selectivity, or elimination of mass transfer limitations by changing from heterogeneous to homogeneous systems. They readily facilitate separations and promote recycling, to promote both green chemistry and good economics. First is near-critical water, ...
An empirical investigation of stock market behavior in the Middle East and North Africa

This paper studies excess market returns in the relatively understudied nancial markets of nine Middle Eastern and North African (MENA) countries within the context of three variants of the Capital Asset Pricing Model: the static international CAPM; the constant-parameter intertemporal CAPM; and a Markov-switching intertemporal CAPM which allows for the degree of integration with international equity markets to be time-varying. On the whole we
Water in silicate melts

Water is one of the more important volatile species in magmas, both in terms of its abundance and its influence on the properties of a given magma. Many workers in the geological sciences have measured, modeled, and speculated on the interaction of water with silicate melts as a function of pressure. At the same time, glass and materials scientists have collected a considerable body of data on the effect of water on the properties of liquid and glassy silicates at 1 atmosphere (1.01325×105 N m−2) and below. A special session on “Solubility and Transport Properties of Water in Silicate Melts” was held during the 1983 AGU Spring Meeting, May 30–June 3, in Baltimore. The session had three main objectives: (1) review the present data base and discuss the status of current models in order to identify areas where further work is needed; (2) introduce interested geologists to the large body of work being carried out in the glass and materials sciences; and (3) consider static properties, such as thermodynamic relations, structure of hydrous melts, and dynamic properties including diffusion and viscosity. This report summarizes the major topics discussed. More detailed information may be found in the published abstracts (Eos, May 3, 1983, pp. 338–343).
Eosinophils Are Recruited in Response to Chitin Exposure and Enhance Th2-Mediated Immune Pathology in Aspergillus fumigatus Infection

In patients infected with the fungus Aspergillus fumigatus, Th1 responses are considered protective, while Th2 responses are associated with increased morbidity and mortality. How host-pathogen interactions influence the development of these protective or detrimental immune responses is not clear. We compared lung immune responses to conidia from two fungal isolates that expressed different levels of the fungal cell wall component chitin. We observed that repeated aspirations of the high-chitin-expressing isolate Af5517 induced increased airway eosinophilia in the lungs of recipient mice compared to the level of eosinophilia induced by isolate Af293. CD4(+) T cells in the bronchoalveolar lavage fluid (BALF) of Af5517-aspirated mice displayed decreased gamma interferon secretion and increased interleukin-4 transcription. In addition, repeated aspirations of Af5517 induced lung transcription of the Th2-associated chemokines CCL11 (eotaxin-1) and CCL22 (macrophage-derived chemokine). Eosinophil recruitment in response to conidial aspiration was correlated with the level of chitin exposure during germination and was decreased by constitutive lung chitinase expression. Moreover, eosinophil-deficient mice subjected to multiple aspirations of Af5517 prior to neutrophil depletion and infection exhibited decreased morbidity and fungal burden compared to the levels of morbidity and fungal burden found in wild-type mice. These results suggest that exposure of chitin in germinating conidia promotes eosinophil recruitment and ultimately induces Th2-skewed immune responses after repeated aspiration. Furthermore, our results suggest that eosinophils should be examined as a potential therapeutic target in patients that mount poorly protective Th2 responses to A. fumigatus infection.
Catalytic enantioselective intramolecular aza-diels-alder reactions.

A readily available chiral Bronsted acid was identified as an efficient catalyst for intramolecular Povarov reactions. Polycyclic amines containing three contiguous stereogenic centers were obtained with excellent stereocontrol in a single step from secondary anilines and aldehydes possessing a pendent dienophile. These transformations constitute the first examples of catalytic enantioselective intramolecular aza-Diels-Alder reactions.
Multi-Engine Machine Translation Guided by Explicit Word Matching

We describe a new approach for synthetically combining the output of several different Machine Translation (MT) engines operating on the same input. The goal is to produce a synthetic combination that surpasses all of the original systems in translation quality. Our approach uses the individual MT engines as "black boxes" and does not require any explicit cooperation from the original MT systems. A decoding algorithm uses explicit word matches, in conjunction with confidence estimates for the various engines and a trigram language model in order to score and rank a collection of sentence hypotheses that are synthetic combinations of words from the various original engines. The highest scoring sentence hypothesis is selected as the final output of our system. Experiments, using several Arabic-to-English systems of similar quality, show a substantial improvement in the quality of the translation output.
Asymmetric effects of trade costs on entry modes: Firm level evidence

Standard foreign direct investment (FDI) theory suggests that falling trade costs should discourage horizontal FDI. Most FDI is horizontal. Yet, the world witnessed an FDI boom in 1990s, a period of striking falls in trade barriers. This paper carries out an empirical analysis with rich, firm-level data on the activities of Swedish multinationals around the globe in manufacturing sectors from 1987 to 1998 to shed light on this apparent conflict. The analysis is based on the predictions of a recent literature with an industrial organization (IO) angle: Trade costs have asymmetric effects on foreign expansion modes. This view posits that falling trade costs encourage entry realized as mergers and acquisitions (M&As), one of the potential explanations for the conflict between received theory and recent trends in FDI. Empirical results confirm the findings of this recent literature and add to it by testing its extensions.
Synthesis and Structure of Alkyl-Substituted Fused Thiophenes Containing up to Seven Rings

We have established a series of synthetic methods to synthesize alkyl-substituted fused thiophenes with degrees of fusion from two to seven rings. These fused thiophene ring compounds have very good solubility in common organic solvents, making possible the solution processing of these compounds for electronic applications. The UV absorption of these fused thiophenes is blue-shifted when compared with their hydrocarbon counterparts. The larger band gaps result in much better stability. Single-crystal X-ray results for 3,6-didecanyldithieno[2,3-d:2‘,3‘-d‘]thieno[3,2-b:4,5-b‘ ‘]dithiophene (FT5) and 3,7-didecanylthieno[3,2-b]thieno[2‘,3‘:4,5]thieno[2,3-d]thiophene (FT4) demonstrate that both compounds form π-stacking structures instead of a herringbone-type of packing motif. This more favorable π-stacked structure may lead to better material electronic properties such as mobility in devices fabricated with these compounds.
Data acquisition and analysis on the two-color-laser transmissometer system

The average particle size and number density in a gas stream are measured by the two-color laser transmissometer in different locations of a magnetohydrodynamic (MHD) power plant. In order to speed up signal collection and analysis, an IBM AT computer is used to control online laser intensity signal sampling and data processing. The operating software, written in the C language, performs data acquisition and data analysis by a series of functional modules. A data conversion board is used for the analog-to-digital signal conversion. The system has been tested and implemented in a test at a pilot scale MHD facility. The measured results illustrate the changes in particle size during the test. >
Regioselective Cyclizations Utilizing a Gold‐Catalyzed [3,3] Propargyl Ester Rearrangement

A concise strategy for the regioselective synthesis of unsaturated carbocycles is demonstrated.
The Long‐Run Performance of REIT Stock Repurchases

∗∗∗ ∗∗∗ This study investigates the long-horizon performance of open-market stock repurchases for real estate investment trusts (REITs). We develop a new methodology to model the autocorrelation of monthly returns into long-horizon buyand-hold abnormal return estimators. Serial correlation can introduce bias (autocorrelation bias) because the bid-ask bounce may affect monthly returns for sample firms and non-sample firms in a different fashion. Previous longhorizon event studies have overlooked this source of bias. There is compelling evidence that the market underreacts to the stock repurchase announcements. The evidence holds for different measures of the variance and the effects of cross-correlation of abnormal returns. Results are also robust to the traditional buy-and-hold abnormal return and the wealth relative estimators. We investigate the nature of the underreaction and find strong support for the undervaluation hypothesis. Measuring performance over long horizons can be “treacherous” (Ikenberry, Lakonishok and Vermaelen 1995, Lyon, Barber and Tsai 1999). The existing literature has identified several potential sources of bias that could affect the reliability of test statistics against the null hypothesis of no long-horizon abnormal returns in the presence of major firm’s events (i.e., IPOs, SEOs, stock repurchase announcements and so on). A number of solutions have been suggested. This article develops a new methodology to analyze the long-run performance of real estate investment trusts (REITs) after the announcement of a stock repurchase program. At the outset, an important question to ask is whether it is worthwhile to study REITs as a separate group independently of other financial or industrial firms. One might conjecture that the extensive finance literature should apply equally to this group, hence there is no need for a study specifically designed for this industry (see the literature review in the next section). However,
Review of Environmental, Economic and Policy Aspects of Biofuels

The world is witnessing a sudden growth in production of biofuels, especially those suited for replacing oil like ethanol and biodiesel. This paper synthesizes what the environmental, economic, and policy literature predicts about the possible effects of these types of biofuels. Another motivation is to identify gaps in understanding and recommend areas for future work. The analysis finds three key conclusions. First, the current generation of biofuels, which is derived from food crops, is intensive in land, water, energy, and chemical inputs. Second, the environmental literature is dominated by a discussion of net carbon offset and net energy gain, while indicators relating to impact on human health, soil quality, biodiversity, water depletion, etc., have received much less attention. Third, there is a fast expanding economic and policy literature that analyzes the various effects of biofuels from both micro and macro perspectives, but there are several gaps. A bewildering array of policies - including energy, transportation, agricultural, trade, and environmental policies - is influencing the evolution of biofuels. But the policies and the level of subsidies do not reflect the marginal impact on welfare or the environment. In summary, all biofuels are not created equal. They exhibit considerable spatial and temporal heterogeneity in production. The impact of biofuels will also be heterogeneous, creating winners and losers. The findings of the paper suggest the importance of the role biomass plays in rural areas of developing countries. Furthermore, the use of biomass for producing fuel for cars can affect access to energy and fodder and not just access to food.
Capacity regions for wireless ad hoc networks

We define and study capacity regions for wireless ad hoc networks with an arbitrary number of nodes and topology. These regions describe the set of achievable rate combinations between all source-destination pairs in the network under various transmission strategies, such as variable-rate transmission, single-hop or multihop routing, power control, and successive interference cancellation (SIC). Multihop cellular networks and networks with energy constraints are studied as special cases. With slight modifications, the developed formulation can handle node mobility and time-varying flat-fading channels. Numerical results indicate that multihop routing, the ability for concurrent transmissions, and SIC significantly increase the capacity of ad hoc and multihop cellular networks. On the other hand, gains from power control are significant only when variable-rate transmission is not used. Also, time-varying flat-fading and node mobility actually improve the capacity. Finally, multihop routing greatly improves the performance of energy-constraint networks.
High retention-time nonvolatile amorphous silicon TFT memory for static active matrix OLED display without pixel refresh

Existing a-Si floating gate TFT (FG-TFT) nonvolatile memory suffers from two drawbacks: (i) short retention time [1] and (ii) strong dependence of drain saturation current (I D,SAT ) on drain voltage [2]. In this study, we present (i) a new device structure that eliminates I D,SAT dependence on drain voltage; (ii) room-temperature retention time of >10 years; and (iii) the integration of this new TFT memory into AMOLED pixels, enabling displays without refresh.
Data grids, collections, and grid bricks

Data grids federate storage resources. They provide a logical name space that can be used to register digital entities, a storage repository abstraction for manipulating data, and a high level abstraction for supporting user-selected interfaces. Data grids can be used to build persistent collections. Data can be stored across multiple types of storage systems with persistent copies kept in archives. Persistent identifiers can be kept in the logical name space. By integrating grid bricks (commodity based disk caches) with archival storage systems, one can assemble a data management environment that supports both interactive access (data picking) and long-term persistent storage. Examples of the creation of interactive data picking environments will be given that integrate grid brick technology with large-scale archives.
On the von neumann entropy of certain quantum walks subject to decoherence

In this paper, we consider a discrete-time quantum walk on the N-cycle governed by the condition that at every time step of the walk, the option persists, with probability p, of exercising a projective measurement on the coin degree of freedom. For a bipartite quantum system of this kind, we prove that the von Neumann entropy of the total density operator converges to its maximum value. Thus, when influenced by decoherence, the mutual information between the two subsystems corresponding to the space of the coin and the space of the walker must eventually diminish to zero. Put plainly, any level of decoherence greater than zero forces the system to become completely ‘disentangled’ eventually.
A Review of the Dynamics of Cavitating Pumps

This paper presents a review of some of the recent developments in our understanding of the dynamics and instabilities caused by cavitation in pumps. Focus is placed on presently available data for the transfer functions for cavitating pumps and inducers, particularly on the compliance and mass flow gain factor which are so critical for pump and system stability. The resonant frequency for cavitating pumps is introduced and contexted. Finally emphasis is placed on the paucity of our understanding of pump dynamics when the device or system is subjected to global oscillation.
An overview of high-temperature electronic device technologies and potential applications

High-temperature electronics applications are found in combustion systems, well logging, and industrial processes, air stagnation points in supersonic aircraft, vehicle brakes, nuclear reactors, and dense electronic packages. We summarize physical effects and materials issues important for reliable operation of semiconductor device technologies at high temperatures (>125/spl deg/C). We review the high-temperature potential of Si, GaAs, other III-V compounds, and SiC. For completeness, we also comment on nitrides, diamond, and vacuum microelectronics. We conclude that Si on insulator (SOI) technology can be developed readily for small signal operation up to about 300/spl deg/C. There is some ongoing work in this area. GaAs offers little advantage over Si because of poor device isolation and the lack of reliable contacts above 250/spl deg/C. Other III-V compounds could be developed for operation to /spl sim/600/spl deg/C, using processes similar to those used for optoelectronics. There may be a market niche for III-V power devices above 200/spl deg/C. There is considerable activity in semiconducting SiC, and device functionality has been demonstrated above 600/spl deg/C. SiC is promising for operation above 300/spl deg/C, and for power devices at frequencies from dc to /spl sim/10 GHz, but it faces numerous challenges to achieve manufacturable status. We attempt to match technologies with application areas. >
A sorting classification of parallel rendering

We describe a classification scheme that we believe provides a more structured framework for reasoning about parallel rendering. The scheme is based on where the sort from object coordinates to screen coordinates occurs, which we believe is fundamental whenever both geometry processing and rasterization are performed in parallel. This classification scheme supports the analysis of computational and communication costs, and encompasses the bulk of current and proposed highly parallel renderers - both hardware and software. We begin by reviewing the standard feed-forward rendering pipeline, showing how different ways of parallelizing it lead to three classes of rendering algorithms. Next, we consider each of these classes in detail, analyzing their aggregate processing and communication costs, possible variations, and constraints they may impose on rendering applications. Finally, we use these analyses to compare the classes and identify when each is likely to be preferable. >
Put Your Imperfections Behind You: Temporal Landmarks Spur Goal Initiation When They Signal New Beginnings

People often fail to muster the motivation needed to initiate goal pursuit. Across five laboratory experiments, we explored occasions when people naturally experience enhanced motivation to take actions that facilitate goal pursuit and why certain dates are more likely to spur goal initiation than others. We present causal evidence that emphasizing a temporal landmark denoting the beginning of a new time period increases people’s intentions to initiate goal pursuit. In addition, we propose and show that people’s strengthened motivation to begin pursuing their aspirations following such temporal landmarks originates in part from the psychological disassociation these landmarks induce from a person’s past, imperfect self.
Distributed control of reactive power flow in a radial distribution circuit with high photovoltaic penetration

We show how distributed control of reactive power can serve to regulate voltage and minimize resistive losses in a distribution circuit that includes a significant level of photovoltaic (PV) generation. To demonstrate the technique, we consider a radial distribution circuit with a single branch consisting of sequentially-arranged residential-scale loads that consume both real and reactive power. In parallel, some loads also have PV generation capability. We postulate that the inverters associated with each PV system are also capable of limited reactive power generation or consumption, and we seek to find the optimal dispatch of each inverter's reactive power to both maintain the voltage within an acceptable range and minimize the resistive losses over the entire circuit. We assume the complex impedance of the distribution circuit links and the instantaneous load and PV generation at each load are known. We compare the results of the optimal dispatch with a suboptimal local scheme that does not require any communication. On our model distribution circuit, we illustrate the feasibility of high levels of PV penetration and a significant (20% or higher) reduction in losses.
Enantioselective Total Synthesis of Callipeltoside A

An asymmetric total synthesis of callipeltoside A has been accomplished highlighted by a catalytic enantioselective vinylogous aldol reaction and a boron-mediated anti-aldol reaction influenced by remote stereocontrol.
Seismic and bathymetric evidence for four different episodes of iceberg scouring on the New Jersey outer shelf: Possible correlation to Heinrich events

Abstract Re-analysis of dense CHIRP seismic surveys on the outer New Jersey shelf reveals two sets of shallowly buried incisions. The incisions are linear to slightly sinuous, oriented ~NE–SW, and exhibit cross-cutting relationships. We interpret both sets as paleo-iceberg scours. One set cuts into the “R” horizon, a regional unconformity that formed ~ 45–40 ka, and which was subsequently buried by the finer-grained outer shelf sediment wedge (OSW). The second set is part of an erose boundary between a layered, lower unit of the OSW and an upper, more transparent unit. The erose boundary scours are deeper and have steeper slopes than the “R” horizon scours. The latter often exhibit bermed edges, whereas the former do not. These differences in cross-sectional morphology are likely determined by the material properties of the sediments being scoured: sand at the “R” horizon, and clay at the erose boundary. The orientation of both sets of scours is consistent with previously recognized iceberg scours in stratigraphically younger seafloor on the outer New Jersey shelf in ~ 110–150 m water depths, located ~ 40 km to the northeast. We argue that Heinrich events, recurring periods of massive iceberg flux into the North Atlantic, represent the most likely times for transporting icebergs to these latitudes. Based on stratigraphic relationships, a recently published ambient sea level curve and radiocarbon age constraints, we attribute the “R” horizon scours to Heinrich event H4 (~ 37 cal ka), the erose boundary scours to H3 (~ 30 cal ka), and the seafloor scours to H2 (~ 23 cal ka) and/or H1 (~ 17 cal ka). Facies changes immediately following the “R” horizon and erose boundary scours may be related to Heinrich event-forced climate changes, perhaps the onset of interstadial conditions and associated melt-water pulses/floods; these pulses/floods repeatedly carried fine-grained rock flour produced by widespread glacial erosion to the New Jersey shelf.
Zero-Bias Conductance Anomaly in Bilayer Quantum Hall Systems

Bilayer quantum Hall system at total filling factor ν=1 shows a rich variety of broken symmetry ground states because of the competition between the interlayer and intralayer Coulomb interactions. When the layers are sufficiently close, a bilayer system develops spontaneous interlayer phase-coherence that manifests itself through a spectacular enhancement of the zero-bias interlayer tunneling conductance. We present a theory of this tunneling conductance anomaly, and show that the zero-bias conductance is proportional to the square of the quasiparticle tunneling amplitude.
Terrestrial planet evolution in the stagnant-lid regime: Size effects and the formation of self-destabilizing crust

The ongoing discovery of terrestrial exoplanets accentuates the importance of studying planetary evolution for a wide range of initial conditions. We perform thermal evolution simulations for generic terrestrial planets with masses ranging from that of Mars to 10M_⊕ in the stagnant-lid regime, the most natural mode of convection with strongly temperature-dependent viscosity. Given considerable uncertainty surrounding the dependency of mantle rheology on pressure, we choose to focus on the end-member case of pressure-independent potential viscosity, where viscosity does not change with depth along an adiabatic temperature gradient. We employ principal component analysis and linear regression to capture the first-order systematics of possible evolutionary scenarios from a large number of simulation runs. With increased planetary mass, crustal thickness and the degree of mantle processing are both predicted to decrease, and such size effects can also be derived with simple scaling analyses. The likelihood of plate tectonics is quantified using a mantle rheology that takes into account both ductile and brittle deformation mechanisms. Confirming earlier scaling analyses, the effects of lithosphere hydration dominate the effects of planetary mass. The possibility of basalt-eclogite phase transition in the planetary crust is found to increase with planetary mass, and we suggest that massive terrestrial planets may escape the stagnant-lid regime through the formation of a self-destabilizing dense eclogite layer.
Oligomeric group 13 hydroxide compounds—a rare but varied class of molecules

This tutorial review surveys the wide variety of oligomeric hydroxide structures formed from aluminum, gallium, and indium. Both inorganic and ligand-supported structures are reviewed, providing a leading introduction to this research area. In addition to homometallic clusters comprising only one metal type, a series of heterometallic structures are described. This review highlights the synthesis and characterization of these nanoscale cluster compounds that have implications in a variety of fields, including catalysis, mineral mimicry, environmental chemistry, geochemistry, materials science, and semiconductors.
Experiments in multidocument summarization

This paper describes a multidocument summarizer built upon research into the detection of new information. The summarizer uses several new strategies to select interesting and informative sentences, including an innovative measure of importance derived from the analysis of a large corpus. The system also computes concept frequencies rather than word frequencies as an additional measure of importance. It merges these strategies with a number of familiar summarization heuristics to rank sentences. The initial version of the summarizer performed successfully in the evaluation reported at the Document Understanding Conference last year, although the system addressed only the content of the summary and not the presentation. We also discuss here the procedures we are developing to improve the presentation and readability of the summaries.
Computer graphics for transportation problems

The central problem in designing transportation systems and networks is determining the optimal control techniques for given transportation facilities. For example, it is essential to find the best strategy for handling the traffic in a given airspace, in a given highway system, or in a network of city streets. The other side of the problem is to determine for given or predicted traffic conditions, the optimal transportation facilities. Urban planners must solve these problems when designing new developments; similarly it is important to determine how many airways and airports will be required to handle the air traffic in the 80's. From the answers to such questions one can decide how to allocate funds, for example, to improve the radar systems to allow smaller separation or to put more navigation aids in order to increase the number of airways.
A novel control method to minimize distortion in AC inverters

In pulse-width-modulation (PWM) AC inverters, the duty-cycle modulator transfer function must be highly linear to achieve low distortion. Current-mode (CM) control, inherently nonlinear, is needed to actively "damp" otherwise high-Q LC noise-reduction filters. A novel CM control approach is proposed which tailors external ramp characteristics to achieve "perfect" transfer function linearity-regardless of duty cycle-and guarantee subharmonic stability. Supporting mathematical analysis and prototype measurements are included. The method, when applied to DC/DC power converters, provides fixed gain bandwidth in the continuous conduction mode over a broad line and load range.
The effect of taxes on shareholder inflows around mutual fund distribution dates

Abstract Taxable investors who are considering purchasing mutual fund shares around the dates when a mutual fund is planning a taxable distribution can reduce the present discounted value of their tax liability by delaying their purchase until after the distribution date. Non-taxable shareholders, such as those who invest through IRAs and other tax-deferred accounts, face no such incentive for delaying a purchase of the fund. This paper compares daily shareholder transactions by taxable and non-taxable investors in the mutual funds of a single no-load fund complex around distribution dates. Gross inflows to taxable accounts are significantly lower in the weeks preceding distribution dates than in the weeks following them, but gross inflows to tax-deferred accounts do not change around these dates. This finding suggests that some taxable shareholders time their purchase of mutual fund shares to avoid the tax acceleration associated with distributions. Taxable shareholders who purchase shares just before distribution dates also have shorter holding periods, on average, than those who buy just after a distribution. Since the cost of the distribution-related tax acceleration for pre-distribution buyers is related to the expected holding period of the shares, this finding provides some evidence of clientele formation among the buyers of mutual fund shares.
Förster resonance energy transfer photoacoustic microscopy

Forster resonance energy transfer (FRET) provides fluorescence signals sensitive to intra- and inter-molecular distances in the 1-10 nm range. Widely applied in the optical imaging environment, FRET enables visualization of physicochemical processes in molecular interactions and conformation changes. We reported photoacoustic imaging of FRET, based on non-radiative decay that produces heat and subsequent acoustic waves. The experimental results show that photoacoustic imaging offers better penetration into scattering biological tissue. Through its ability to three-dimensionally image tissue with scalable resolution, photoacoustic microscopy provides a beneficial biomedical tool to broaden the in vivo application of the FRET technique.
Detection of prohibited treatment products on racing tires using headspace solid phase microextraction (SPME) and gas chromatography/mass spectrometry (GC/MS)

A variety of commercial tire treatments are available that purport to help automobile tires better cling to the surface of a road or racetrack, raising concerns in the professional racing community that such products might be used to illicitly boost performance in competitive events. These tire treatments are reputed to cut lap times and improve handling and maneuverability. In some cases, the manufacturers even boast that their products are “undetectable” (i.e., impervious to the scrutiny of laboratory testing). In this study, a number of banned tire treatment products were evaluated principally by gas chromatography-mass spectrometry (GC-MS) using solid phase microextraction (SPME) as a pre-concentration technique. The chemicals off-gassed by each product were determined and grouped into two broad categories: ‘plasticizer-based’ tire treatment products and ‘hydrocarbon-based’ tire treatment products. This information was then applied to the analysis of genuine tire samples provided by the United States Auto Club (USAC), a professional racing association. Over the course of one year, 10 out of the 71 questioned samples tested positive for a prohibited treatment product. The manufacturers' claims regarding their products' invisibility to lab tests were largely proven to be unfounded: both the products themselves and the tires treated with them can be identified by a number of characteristic volatile compounds. These included known plasticizers such as pentanedioic acid diethyl ester, plasticizer-related compounds such as 2-ethyl-1-hexanol, and dearomatized distillates.
Micromilling of metal alloys with focused ion beam–fabricated tools

Abstract This work combines focused ion beam sputtering and ultra-precision machining as a first step in fabricating metal alloy microcomponents. Micro-end mills having ∼25 μm diameters are made by sputtering cobalt M42 high-speed steel and C2 micrograin tungsten carbide tool blanks. A 20 keV focused gallium ion beam is used to define a number of cutting edges and tool end clearance. Cutting edge radii of curvature are less than or equal to 0.1 μm. Micro-end mill tools having 2, 4 and 5 cutting edges successfully machine millimeter long trenches in 6061-T4 aluminum, brass, 4340 steel and polymethyl methacrylate. Machined trench widths are approximately equal to the tool diameters, and surface roughnesses (Ra) at the bottom of micromachined features are ∼200 nm. Microtools are robust and operate for more than 6 h without fracture. Results from ultra-precision machining aluminum alloy at feed rates as high as 50 mm/minute and an axial depth of 1.0 μm are included.