cssi/SciSciGPT-SciSciNet huggingface dataset:
Self-trapping of necklace beams in self focusing Kerr media

Summary form only given. Solitons of the cubic nonlinear Schrodinger equation (NLSE) are probably the most studied solitons in nature. One of the reasons is the mathematical elegance and simplicity of this equation. But another more important reason is the vast number of physical systems that can be described by this equation. Single polarization envelope waves propagating in isotropic materials, when only the lowest order nonlinearity matters most often obey this equation. In optics, the cubic NLSE models temporal solitons in optical fibers, and low intensity solitons of all dimensions in any centrosymmetric media. Here, we present numerical simulations demonstrating the existence of what is to the best of our knowledge the first ever described (2+1)D self-trapped family of stable bright beams in the (2+1)D cubic NLSE.
Approaching the Island of Inversion: 34P

Yrast states in {sup 34}P were investigated using the {sup 18}O({sup 18}O,pn) reaction at energies of 20, 24, 25, 30, and 44 MeV at Florida State University and at Lawrence Berkeley National Laboratory. The level scheme was expanded, {gamma}-ray angular distributions were measured, and lifetimes were inferred with the Doppler-shift attenuation method by detecting decay protons in coincidence with one or more {gamma} rays. The results provide a clearer picture of the evolution of structure approaching the ''island of inversion,'' particularly how the one- and two-particle-hole (ph) states fall in energy with increasing neutron number approaching inversion. However, the agreement of the lowest few states with pure sd shell model predictions shows that the level scheme of {sup 34}P is not itself inverted. Rather, the accumulated evidence indicates that the 1-ph states start at 2.3 MeV. A good candidate for the lowest 2-ph state lies at 6236 keV, just below the neutron separation energy of 6291 keV. Shell model calculations made using a small modification of the WBP interaction reproduce the negative-parity, 1-ph states rather well.
Super-Resolution from Noisy Data

This paper studies the recovery of a superposition of point sources from noisy bandlimited data. In the fewest possible words, we only have information about the spectrum of an object in the low-frequency band [−f lo,f lo] and seek to obtain a higher resolution estimate by extrapolating the spectrum up to a frequency f hi>f lo. We show that as long as the sources are separated by 2/f lo, solving a simple convex program produces a stable estimate in the sense that the approximation error between the higher-resolution reconstruction and the truth is proportional to the noise level times the square of the super-resolution factor (SRF) f hi/f lo.
Surface-discharge switch design: the critical factor

Dielectric properties that are critical to designing a long-life surface-discharge switch (SDS) are investigated. Theory is correlated with experiment by evaluating the performance of a large group of polymeric and ceramic dielectrics. These dielectrics are tested in a single-channel, self-commutating SDS operating at approximately 35 kV and approximately 300 kA (oscillatory discharge) with a pulse length of approximately 20 mu s (1/4 period approximately 2 mu s). The performance of a dielectric is characterized by its shot-to-shot breakdown voltage and by its mass erosion. Theoretically, the voltage holdoff degradation resistance (HDR) and the arc melting/erosion resistance (AMR) of a dielectric can be qualitatively predicted from its formativity and its impulsivity, respectively. The formativity and impulsivity are figures of merit calculated from the known thermophysical properties of the dielectric. The effects produced in dielectric performance by choice of electrode material (e.g., molybdenum, graphite, and copper-tungsten) and discharge repetition rate are also discussed. >
Statistical theory of the continuous double auction

Abstract Most modern financial markets use a continuous double auction mechanism to store and match orders and facilitate trading. In this paper we develop a microscopic dynamical statistical model for the continuous double auction under the assumption of IID random order flow, and analyse it using simulation, dimensional analysis, and theoretical tools based on mean field approximations. The model makes testable predictions for basic properties of markets, such as price volatility, the depth of stored supply and demand versus price, the bid–ask spread, the price impact function, and the time and probability of filling orders. These predictions are based on properties of order flow and the limit order book, such as share volume of market and limit orders, cancellations, typical order size, and tick size. Because these quantities can all be measured directly there are no free parameters. We show that the order size, which can be cast as a non-dimensional granularity parameter, is in most cases a more signi...
Changes in the size and location of kidneys from the supine to standing positions and the implications for block placement during total body irradiation.

Abstract Purpose: The use of total body irradiation (TBI) as a conditioning regimen for bone marrow transplantation often calls for partial transmission kidney blocks. These blocks are frequently designed based on the location of the kidneys during the abdominal computerized tomography (CT) scan. At our institution, TBI patients are treated in the standing position. As the kidneys can shift with different patient positions, a study was undertaken to evaluate the magnitude of the changes in the size and location of the kidneys from the supine CT position to the upright treatment position. Methods and Materials: Intravenous contrast was administered to 15 patients. The patients were initially positioned supine on a simulator table and then positioned upright immediately in front of the image intensifier. PA radiographs were obtained with the patients in both positions. Changes in the size of the kidneys and their location relative to the vertebral bodies were noted. Results: In going from the supine to upright position, all the kidneys shifted inferiorly between 0.5 cm and 7.5 cm with an average of 3.6 cm. Most of the kidneys also shifted in the transverse dimension and incurred a change in width. The range of the transverse shift was from 0.9 cm in the lateral direction to 4.9 cm medially. The maximum width broadening was 1.2 cm and the maximum decrease in width was 1.8 cm. Conclusions: When compared to the supine position, patients in the upright position show a dramatic inferior shift of the kidneys with other obvious, but less predictable, changes. For TBI treatments delivered in the upright position, kidney blocks should not be designed on the basis of supine abdominal CT scans.
Unified Planar Process For Fabricating Heterojunction Bipolar Transistors And Buried Heterostructure Lasers Utilizing Impurity Induced Disordering

One goal of optoelectronic integration is to realize a low-threshold laser structure and a transistor structure of the same substrate. In pursuit of this goal, the authors have developed a novel transistor structure which they call a lateral heterojunction bipolar transistor (L-HBT). Impurity-induced disordering (IID) accomplished by silicon diffusion is used to convert a buried p-type GaAs layer into n-type AlGaAs regions that serve as the emitter and collector of the heterojunction bipolar transistor. The resulting transistor structure is completely planar, and current flow from the emitter through the base to the collector occurs in the plane of the base layer as opposed to perpendicular to the plane of the base layer, as is the case in conventional heterojunction bipolar transistors. The authors have fabricated this transistor structure and observed transistor action with a maximum current gain of beta =5-10 for base widths of 1.4 mu m. They have also observed room-temperature laser operation from the transistor structure with a threshold current of 6 mA for the same 1.4- mu m-wide stripe that exhibits transistor action. This threshold current value compares favorably with those routinely obtained in a more conventional buried heterostructure laser. They refer to this laser structure as a heterotransverse junction (HTJ) laser, due to the fact that current is injected along the plane of the epitaxial layers. The geometry of the laser is suitable for applications involving high-speed modulation and/or integration with other optoelectronic components. >
The Causes and Consequences of Cross-Country Differences in Schooling Attainment

This paper uses labor market evidence to quantify the importance of quality-adjusted schooling differences in accounting for cross-country income differences. I model labor markets that are consistent with cross-country data on schooling attainment, education quality, and the average returns to schooling of a country’s emigrants and its non-migrants. The model suggests that the Mincerian returns to schooling of immigrants to the United States measure the education qualities of their source countries. Measured this way, quality differences across countries are large, and the calibrated model shows that schooling accounts for a factor of 5 of the income difference between the U.S. and the poorest countries. The evidence suggests that immigrants to the U.S. are positively selected members of their source country, and that immigrants from developing countries are more selected than those from developed countries. Then the low education quality measured in the sample actually overestimates the education quality of the average non-migrant, particularly for developing countries. Two methods of controlling for selection among immigrants thus predict a moderately larger role for schooling, between a factor of 6.5 and 7.9.
Mutations in the Caenorhabditis elegans U2AF large subunit UAF-1 alter the choice of a 3′ splice site in vivo.

The removal of introns from eukaryotic RNA transcripts requires the activities of five multi-component ribonucleoprotein complexes and numerous associated proteins. The lack of mutations affecting splicing factors essential for animal survival has limited the study of the in vivo regulation of splicing. From a screen for suppressors of the Caenorhabditis elegans unc-93(e1500) rubberband Unc phenotype, we identified mutations in genes that encode the C. elegans orthologs of two splicing factors, the U2AF large subunit (UAF-1) and SF1/BBP (SFA-1). The uaf-1(n4588) mutation resulted in temperature-sensitive lethality and caused the unc-93 RNA transcript to be spliced using a cryptic 3′ splice site generated by the unc-93(e1500) missense mutation. The sfa-1(n4562) mutation did not cause the utilization of this cryptic 3′ splice site. We isolated four uaf-1(n4588) intragenic suppressors that restored the viability of uaf-1 mutants at 25°C. These suppressors differentially affected the recognition of the cryptic 3′ splice site and implicated a small region of UAF-1 between the U2AF small subunit-interaction domain and the first RNA recognition motif in affecting the choice of 3′ splice site. We constructed a reporter for unc-93 splicing and using site-directed mutagenesis found that the position of the cryptic splice site affects its recognition. We also identified nucleotides of the endogenous 3′ splice site important for recognition by wild-type UAF-1. Our genetic and molecular analyses suggested that the phenotypic suppression of the unc-93(e1500) Unc phenotype by uaf-1(n4588) and sfa-1(n4562) was likely caused by altered splicing of an unknown gene. Our observations provide in vivo evidence that UAF-1 can act in regulating 3′ splice-site choice and establish a system that can be used to investigate the in vivo regulation of RNA splicing in C. elegans.
Autologous stem cell transplantation for multiple myeloma in patients over 70 years: A matched comparison with patients under 65 years

Background: High dose therapy with autologous stem cell rescue has been shown to prolong survival in patients with multiple myeloma in randomized controlled trials. However, most of the prospective studies have included younger patients, usually 65 or less. It is important to have a better understanding of the outcome of transplantation in the older patients given the median age of onset of myeloma of 65 years. We retrospectively reviewed our institutions experience with high dose therapy for patients over 70 years. Methods: We identified 35 patients with multiple myeloma, from the transplant database, who were at or over the age of 70 at the time of their high dose therapy. We matched these patients to 70 patients (two matches for each patient), based on stage at transplant (primary refractory, plateau phase, relapse off therapy, or relapse on therapy), Durie Salmon stage, high or low labeling index, conventional cytogenetics (abnormal vs normal), presence or absence of circulating plasma cells at time of transplant, and whether cyclophosphamide was used as part of mobilization in that order of priority. Results: The median age of the two groups were 55.3 (Range 37.3–64.8) and 71.7 (Range 70–75.8) years at the time of transplant. The median time to transplant from diagnosis was similar (6.4 for the older patients compared to 6.9 months for the other, P = NS). Ten of the 35 older patients received reduced dose melphalan (140 mg/2)) compared to 3 patients in the control group; P Conclusions: High dose therapy and autologous stem cell transplantation is feasible in selected patients with multiple myeloma over 70 years. It is likely that these older patients were selected based on their overall performance status, a factor that is difficult to analyze in this retrospective review. Nearly 70% of the elderly patients received full dose melphalan for conditioning (200 mg/m2). The toxicity of transplant as well as the outcome appears to be very similar to the younger patients. Patients with multiple myeloma should not be excluded from high dose therapy solely on the basis of their chronological age.
Accounting for Co-Teaching: A Guide for Policymakers and Developers of Value-Added Models

AbstractWe outline the options available to policymakers for addressing co-teaching in a value-added model. Building on earlier work, we propose an improvement to a method of accounting for co-teaching that treats co-teachers as teams, with each teacher receiving equal credit for co-taught students. Hock and Isenberg (2012) described a method known as the Full Roster Method (FRM) that is feasible and practical, but it effectively counts co-taught students more than once—these students receive a full weight with each of their teachers, so such students receive extra weight when calculating the relationship between student characteristics and achievement. The improvement, known as the Full Roster-Plus Method, allows co-taught students to receive full weight with their teachers, but all students contribute equally to the calculation of the relationship between student characteristics and achievement. To investigate how the application of this method empirically changes value-added estimates, we use data from...
A Simple Bargaining Model where Parties Make Errors

In this paper, we develop a bargaining model where parties (or their intermediaries) make errors when reporting their bid. We characterize the Nash equilibria of the game and show that there is a unique equilibrium where trade takes place. This trade equilibrium is shown to converge to the Nash Bargaining Solution of the problem as trembles diminish. Finally, we discuss our results in the context of the previous literature providing a critique of the model and analysis found in Carlsson (1991).
Lawyer advising in evidence disclosure

This paper examines how the advice that lawyers provide to their clients affects the disclosure of evidence and the outcome of adjudication, and how the adjudicator should allocate the burden of proof in light of these effects. Despite lawyers' expertise in assessing the evidence, their advice is found to have no effect on adjudication, if the lawyers follow disclosure strategies that are undominated in a certain sense. A lawyer's advice can influence the outcome to his client's favor, if he can credibly advise his client to suppress some favorable evidence, but this effect is socially undesirable.
Palladium(0) catalysis in hydrostannation of carbon-carbon triple bonds

Abstract Palladium catalyzed hydrostannation of acetylenes results in a high degree of regioselectivity and stereoselectivity, as well as good overall yields.
Assessing Aircraft Susceptibility to Nonlinear Aircraft-Pilot Coupling/Pilot-Induced Oscillations

A unified approach for assessing aircraft susceptibility to aircraft-pilot coupling (or pilot-induced oscillations) which was previously reported in the literature and applied to linear systems is extended to nonlinear systems, with emphasis upon vehicles with actuator rate saturation. The linear methodology provided a tool for predicting: (1) handling qualities levels, (2) pilot-induced oscillation rating levels and (3) a frequency range in which pilot-induced oscillations are likely to occur. The extension to nonlinear systems provides a methodology for predicting the latter two quantities. Eight examples are presented to illustrate the use of the technique. The dearth of experimental flight-test data involving systematic variation and assessment of the effects of actuator rate limits presently prevents a more thorough evaluation of the methodology.
Performance of a prototype CMS hadron barrel calorimeter in a test beam

We report on the performance of a prototype CMS Hadron Barrel Calorimeter (HCAL) module in a test beam. The prototype sampling calorimeter used copper absorber plates and scintillator tiles with wavelength shifting fibers for readout. Placing a lead tungstate crystal electromagnetic calorimeter in front of HCAL affects the linearity and energy resolution of the combined system to hadrons. The data are used to optimize the choice of total absorber depth, sampling frequency, and longitudinal readout segmentation.
Scaling up malaria control in Africa: an economic and epidemiological assessment.

This paper estimates the number of people at risk of contracting malaria in Africa using GIS methods and the disease's epidemiologic characteristics. It then estimates yearly costs of covering the population at risk with the package of interventions (differing by level of malaria endemicity and differing for rural and urban populations) for malaria as recommended by the UN Millennium Project. These projected costs are calculated assuming a ramp-up of coverage to full coverage by 2008, and then projected out through 2015 to give a year-by-year cost of meeting the Millennium Development Goal for reducing the burden of malaria by 75%. We conclude that the cost of comprehensive malaria control for Africa is US$3.0 billion per year on average, or around US$4.02 per African at risk.
Efficient simulation of multidimensional phonon transport using energy-based variance-reduced Monte Carlo formulations

We present a Monte Carlo method for obtaining solutions of the Boltzmann equation to describe phonon transport in micro- and nanoscale devices. The proposed method can resolve arbitrarily small signals (e.g., temperature differences) at small constant cost and thus represents a considerable improvement compared to traditional Monte Carlo methods, whose cost increases quadratically with decreasing signal. This is achieved via a control-variate variance-reduction formulation in which the stochastic particle description solves only for the deviation from a nearby equilibrium, while the latter is described analytically. We also show that simulation of an energy-based Boltzmann equation results in an algorithm that lends itself naturally to exact energy conservation, thereby considerably improving the simulation fidelity. Simulations using the proposed method are used to investigate the effect of porosity on the effective thermal conductivity of silicon. We also present simulations of a recently developed thermal conductivity spectroscopy process. The latter simulations demonstrate how the computational gains introduced by the proposed method enable the simulation of otherwise intractable multiscale phenomena.
Distributional Impacts of Carbon Pricing: A General Equilibrium Approach with Micro-Data for Households

article i nfo Many policies to limit greenhouse gas emissions have at their core efforts to put a price on carbon emissions. Carbon pricing impacts households both by raising the cost of carbon intensive products and by changing factor prices. A complete analysis requires taking both effects into account. The impact of carbon pricing is determined by heterogeneity in household spending patterns across income groups as well as heterogeneity in factor income patterns across income groups. It is also affected by precise formulation of the policy (how is the revenue from carbon pricing distributed) as well as the treatment of other government policies (e.g. the treatment of transfer payments). What is often neglected in analyses of policy is the heterogeneity of impacts across households even within income or regional groups. In this paper, we incorporate 15,588 households from the U.S. Consumer and Expenditure Survey data as individual agents in a comparative-static general equilibrium framework. These households are represented within the MIT USREP model, a detailed general equilibrium model of the U.S. economy. In particular, we categorize households by full household income (factor income as well as transfer income) and apply various measures of lifetime income to distinguish households that are temporarily low-income (e.g., retired households drawing down their financial assets) from permanently low-income households. We also provide detailed within-group distributional measures of burden impacts from various policy scenarios.
Correlation of Magnus Force Data for Slender Spinning Cylinders

Time-dependent results of numerical finite-difference solution for the two-dimensional spinning circular cylinder are used to derive a correlation parameter for analysis of experimental Magnus force data. The correlation parameter, which is a function of angle of attack, the fineness ratio, and the Reynolds number, is derived on the basis of the impulse or cross-flow analogy. The correlation parameter, derived for finless slender spinning circular cylinders is shown to successfully correlate experimental data for fineness ratios from 6 to 24, for subsonic through supersonic freestream speeds, and for cross-flow Mach numbers up to 0.4 at transonic and supersonic speeds. Cy = Cyp = d = k = / = M p p t t/oo Uc V x 7 a v p Nomenclature two-dimensional lift coefficient, lift per unit span/(l/2)p Uc2 d local side-force coefficient, side-force per unit span/(l/2)p Uc2 d = Magnus force coefficient, 87/pl/^2 nd2p = body diameter = constant of proportionality = body length = freestream Mach number = spin rate = dimensionless spin rate, pd/211^ = time = freestream speed = component of freestream speed normal to body axis = tangential surface speed due to spin = distance along body axis from nose = Magnus force = angle of attack = kinematic viscosity = air density
Self-Poling of Thin BaTiO3 Films by Contact Potential Difference

The substrate dependence of the ferroelectric properties of sol-gel derived BaTiO3 thin films was investigated. Thin (0.35 µm) films were deposited on Si substrates of various orientations and doping. Films deposited on p+ Si (1020 cm−3 B, 2% Ge) (110) were self-poled. The poling direction is self-restoring even after being reversed by an external bias or heated above the Curie temperature. The pyroelectric coefficient was not zero above the Curie point, which indicated that the films were permanently subjected to an electric field, which originates from the contact potential between the film and the substrate. Thisconclusion was confirmed by surface photo voltage spectroscopy. The possibility of a paraelectric to ferroelectric transition driven by an electric field due to the contact potential difference must be taken into account for dynamic random access memory (DRAM) applications.
High-Performance Algorithm Engineering for Computational Phylogenetics

A phylogeny is the evolutionary history of a group of organisms; systematists (and other biologists) attempt to reconstruct this history from various forms of data about contemporary organisms. Phylogeny reconstruction is a crucial step in the understanding of evolution as well as an important tool in biological, pharmaceutical, and medical research. Phylogeny reconstruction from molecular data is very difficult: almost all optimization models give rise to NP-hard (and thus computationally intractable) problems. Yet approximations must be of very high quality in order to avoid outright biological nonsense. Thus many biologists have been willing to run farms of processors for many months in order to analyze just one dataset. High-performance algorithm engineering offers a battery of tools that can reduce, sometimes spectacularly, the running time of existing phylogenetic algorithms, as well as help designers produce better algorithms. We present an overview of algorithm engineering techniques, illustrating them with an application to the “breakpoint analysis” method of Sankoff et al., which resulted in the GRAPPA software suite. GRAPPA demonstrated a speedup in running time by over eight orders of magnitude over the original implementation on a variety of real and simulated datasets. We show how these algorithmic engineering techniques are directly applicable to a large variety of challenging combinatorial problems in computational biology.
Alumina-mediated deacetylation of benzaldehyde diacetates. A simple deprotection method

Abstract A simple, extremely fast, and high yielding method for the selective deprotection of benzaldehyde diacetates is described which occurs under mild conditions on neutral alumina surface. Gentle heating, using microwave irradiation or conventional methods facilitates the procedure.
Automatic Annotation and Retrieval of Images

Although a variety of techniques have been developed for content-based image retrieval (CBIR), automatic image retrieval by semantics still remains a challenging problem. We propose a novel approach for semantics-based image annotation and retrieval. Our approach is based on the monotonic tree model. The branches of the monotonic tree of an image, termed as structural elements, are classified and clustered based on their low level features such as color, spatial location, coarseness, and shape. Each cluster corresponds to some semantic feature. The category keywords indicating the semantic features are automatically annotated to the images. Based on the semantic features extracted from images, high-level (semantics-based) querying and browsing of images can be achieved. We apply our scheme to analyze scenery features. Experiments show that semantic features, such as sky, building, trees, water wave, placid water, and ground, can be effectively retrieved and located in images.
Reliability of Banks' Fair Value Disclosure for Loans

This study investigates whether banks manage the disclosed fair value of their major asset, the loan portfolio. Using two cross-section samples, I find evidence that suggests banks manage the fair value of loans. The estimated extent of overstatement of loans' fair value is negatively related to regulatory capital, asset growth, liquidity and the gross book value of loans, and positively related to the change in the rate of credit losses. These relations imply that some banks overstate the disclosed fair value of loans in an attempt to favorably affect the market assessment of their risk and performance.
Students' models of Newton's second law in mechanics and electromagnetism

We investigated students' use of Newton's second law in mechanics and electromagnetism contexts by interviewing students in a two-semester calculus-based physics course. We observed that students' responses are consistent with three mental models, Newtonian, Aristotelian, and a hybrid model formed with elements of the first two models. These models appeared in mechanics contexts and were transferred to electromagnetism contexts. We developed an inventory to help instructors identify these models and direct students towards the correct one.
Permutohedra, Associahedra, and Beyond

The volume and the number of lattice points of the permutohedron Pn are given by certain multivariate polynomials that have remarkable com- binatorial properties. We give 3 dieren t formulas for these polynomials. We also study a more general class of polytopes that includes the permutohedron, the associahedron, the cyclohedron, the Stanley-Pitman polytope, and various generalized associahedra related to wonderful compactications of De Concini- Procesi. These polytopes are constructed as Minkowsky sums of simplices. We calculate their volumes and describe their combinatorial structure. The coef- cien ts of monomials in Vol Pn are certain positive integer numbers, which we call the mixed Eulerian numbers. These numbers are equal to the mixed volumes of hypersimplices. Various specializations of these numbers give the usual Eulerian numbers, the Catalan numbers, the numbers (n+1) n 1 of trees (or parking functions), the binomial coecien ts, etc. We calculate the mixed Eulerian numbers using certain binary trees. Many results are extended to an arbitrary Weyl group.
Dynamic climate policy with both strategic and non-strategic agents : taxes versus quantities

We study a dynamic game where blocs of fossil fuel importers and exporters exercise market power using taxes or quotas. A non-strategic fringe of emerging and developing countries consume and produce fossil fuels. Cumulated emissions from fossil fuel consumption create climate damages. We examine Markov perfect equilibria under the four combinations of trade policies, and compare these to the corresponding static games. Taxes dominate quotas for both the strategic importer and exporter; the fringe is better off under taxes than quotas, because taxes result in lower fuel prices and less consumption by the strategic importer, lowering climate damages.
Information Focus and Data Sources When Will They Lead to Use

Information utilization was examined among 90 social service decision makers. Results indicated that propensity to use a particular type of information is relatively independent of the propensity to use a particular source from which the information is obtained. Moreover, the information type used by a decision maker is predicted in part by the type of decision needing to be made. In contrast, use of a particular source is related to the decision maker's role. Suggestions for evaluators concerned with utilization of their information as well as for researchers developing theories of information use are offered.
Beyond Panglossian theory: strategic capital investing in a complex adaptive world

Traditional capital budgeting theory (as an extension of financial economics) is characterized as Panglossian because of its suggestion that rational market outcomes produce the best of all possible worlds. During the last two decades, practice-oriented theorists have increasingly been moving from algorithmic capital budgeting techniques to a focus on capital investment strategy. Also, during the last twelve years, economics researchers at the Santa Fe Institute (SFI) have scrapped the dubious assumptions of neoclassical economics and have turned to complex adaptive systems theory for a more realistic portrayal of the economy. This paper explores various SFI studies and their implications for capital investment theory and capital investment strategy. Brian Arthur’s theory of increasing returns undermines the notion that capital budgeting techniques can be counted on to generate economic eAciency. His theory further suggests that the high tech, knowledge-based sectors of the economy inherently produce outcomes that are too unpredictable for the meaningful application of traditional capital budgeting techniques. Studies by David Lane and his colleagues suggest that the identity of agents, the attributes of artifacts and the possibilities for action tend to be emergent phenomena that are generated by the interactions of agents. These considerations suggest a form of strategic action that focuses on process. Finally, it is argued that the artificial life and other SFI types of computer simulation models are potentially useful tools for the study of strategic capital investment decisions. # 2000 Elsevier Science Ltd. All rights reserved.
3-D Topologies for Networks-on-Chip

Several interesting topologies emerge by incorporating the third dimension in networks-on-chip (NoC). The speed and power consumption of 3D NoC are compared to that of 2D NoC. Physical constraints, such as the maximum number of planes that can be vertically stacked and the asymmetry between the horizontal and vertical communication channels of the network, are included in speed and power consumption models of these novel 3D structures. An analytic model for the zero-load latency of each network that considers the effects of the topology on the performance of a 3D NoC is developed. Tradeoffs between the number of nodes utilized in the third dimension, which reduces the average number of hops traversed by a packet, and the number of physical planes used to integrate the functional blocks of the network, which decreases the length of the communication channel, is evaluated for both the latency and power consumption of a network. A performance improvement of 40% and 36% and a decrease of 62% and 58% in power consumption is demonstrated for 3D NoC as compared to a traditional 2D NoC topology for a network size of N = 128 and N = 256 nodes, respectively.
Magnetohydrodynamic simulations of shock interactions with radiative clouds

We present results from two-dimensional numerical simulations of the interactions between magnetized shocks and radiative clouds. Our primary goal is to characterize the dynamical evolution of the shocked clouds. We perform runs in both the strong and weak magnetic field limits and consider three different field orientations. For the geometries considered, we generally find that magnetic fields external to, but concentrated near, the surface of the cloud suppress the growth of destructive hydrodynamic instabilities. External fields also increase the compression of the cloud by effectively acting as a confinement mechanism driven by the interstellar flow and local field stretching. This can have a dramatic effect on both the efficiency of radiative cooling, which tends to increase with increasing magnetic field strength, and on the size and distribution of condensed cooled fragments. In contrast, fields acting predominately internally to the cloud tend to resist compression, thereby inhibiting cooling. We observe that, even at modest strengths (β0 100), internal fields can completely suppress low-temperature (T < 100 K) cooling in two-dimensional clouds.
Total synthesis of complex heterocyclic natural products

Total synthesis campaigns toward complex heterocyclic natural products are a prime source of inspiration for the design and execution of complex cascade sequences, powerful reactions, and efficient synthetic strategies. We highlight selected examples of such innovations in the course of our total syntheses of diazonamide A, azaspiracid-1, thio- strepton, 2,2'-epi-cytoskyrin A and rugulosin, abyssomicin C, platensimycin, and unci- alamycin.
Market structure and Schumpeterian growth

Abstract We present a discrete-time version of a Schumpeterian growth model. A natural R&D analogue to constant returns to scale implies a Poisson production function with diminishing marginal product. Surprisingly, the industry demand for R&D inputs does not depend on the number of firms in the R&D sector if Bertrand competition ensues following ties. In contrast, demand is higher if ties result in collusion. In general equilibrium, Bertrand competition leads to random switching between monopoly and competitive production. Under collusion, production is always at the monopoly level, but there is faster growth. Numerical simulations suggest that this leads to higher welfare.
The Secret Life of Mundane Transaction Costs

Transaction costs, one often hears, are ‘the economic equivalent of friction in physical systems’. Like physicists, economists can sometimes neglect friction in formulating theories; but like engineers, they can never neglect friction in studying how the system actually does — let alone should — work. Interestingly, however, the present-day economics of organization also ignores friction. That is, almost single-mindedly, the literature analyzes transactions from the point of view of misaligned incentives and (especially) transaction-specific assets. The costs involved are certainly costs of running the economic system in some sense, but they are not obviously ‘frictions’. Stories about frictions in trade are not nearly as intriguing as stories about guileful trading partners and expensive assets placed at risk. But I will argue that these seemingly dull categories of cost — what Baldwin and Clark call mundane transaction costs — actually have a secret life. They are at least as important as, and quite pro...
A Branch-and-Bound Algorithm for Zero-One Mixed Integer Programming Problems

This paper presents the results of experimentation on the development of an efficient branch-and-bound algorithm for the solution of zero-one linear mixed integer programming problems. An implicit enumeration is employed using bounds that are obtained from the fractional variables in the associated linear programming problem. The principal mathematical result used in obtaining these bounds is the piecewise linear convexity of the criterion function with respect to changes of a single variable in the interval [0, 1]. A comparison with the computational experience obtained with several other algorithms on a number of problems is included.
Structured feature selection and task relationship inference for multi-task learning

Multi-task learning (MTL) aims to enhance the generalization performance of supervised regression or classification by learning multiple related tasks simultaneously. In this paper, we aim to extend the current MTL techniques to high dimensional data sets with structured input and structured output (SISO), where the SI means the input features are structured and the SO means the tasks are structured. We investigate a completely ignored problem in MTL with SISO data: the interplay of structured feature selection and task relationship modeling. We hypothesize that combining the structure information of features and task relationship inference enables us to build more accurate MTL models. Based on the hypothesis, we have designed an efficient learning algorithm, in which we utilize a task covariance matrix related to the model parameters to capture the task relationship. In addition, we design a regularization formulation for incorporating the structured input features in MTL. We have developed an efficient iterative optimization algorithm to solve the corresponding optimization problem. Our algorithm is based on the accelerated first order gradient method in conjunction with the projected gradient scheme. Using two real-world data sets, we demonstrate the utility of the proposed learning methods.
Nuclear Shapes Studied by Coulomb Excitation

Publisher Summary This chapter discusses nuclear shapes studied by Coulomb excitation. Nuclear E2 properties are a direct and an unambiguous measure of the collective shape parameters for quadrupole collectivity. Coulomb excitation selectively excites collective states with cross sections that are a direct measure of the E2 matrix elements. Advances in the field of Coulomb excitation make it feasible to measure essentially all the E2 matrix elements for low-lying nuclear levels. The completeness and extent of this E2 information add a new dimension to the study of quadrupole collectivity in nuclei. In particular, now it is practical to use a model-independent method for extracting the collective shape parameters directly from this large body of E2 data. Coulomb excitation can now be used to address open questions such as those regarding the limits of the validity of macroscopic collective models, the role of symmetries in collective motion, and the role of shape transitions and shape coexistence in nuclear structure. It is possible to exploit the model-independent sum rule method to project the significant quadrupole collective shape degrees of freedom directly from the data. The power of the sum rule technique is that it allows a wealth of data to be transformed into a form that clearly shows the extent to which the data are correlated because of collectivity.
Global variation of the dust-to-gas ratio in evolving protoplanetary discs

Recent theories suggest planetesimal formation via streaming and/or gravitational instabilities may be triggered by localized enhancements in the dust-to-gas ratio, and one hypothesis is that sufficient enhancements may be produced in the pile-up of small solid particles inspiralling under aerodynamic drag from the large mass reservoir in the outer disc. Studies of particle pile-up in static gas discs have provided partial support for this hypothesis. Here, we study the radial and temporal evolution of the dust-to-gas ratio in turbulent discs that evolve under the action of viscosity and photoevaporation. We find that particle pile-ups do not generically occur within evolving discs, particularly if the introduction of large grains is restricted to the inner, dense regions of a disc. Instead, radial drift results in depletion of solids from the outer disc, while the inner disc maintains a dust-to-gas ratio that is within a factor of ∼2 of the initial value. We attribute this result to the short time-scales for turbulent diffusion and radial advection (with the mean gas flow) in the inner disc. We show that the qualitative evolution of the dust-to-gas ratio depends only weakly upon the parameters of the disc model (the disc mass, size, viscosity and value of the Schmidt number), and discuss the implications for planetesimal formation via collective instabilities. Our results suggest that in discs where there is a significant level of midplane turbulence and accretion, planetesimal formation would need to be possible in the absence of large-scale enhancements. Instead, trapping and concentration of particles within local turbulent structures may be required as a first stage of planetesimal formation.
Dividend Changes and Future Profitability

We investigate the relation between dividend changes and future profitability, measured in terms of either future earnings or future abnormal earnings. Supporting "the information content of dividends hypothesis," we find that dividend changes provide information about the level of profitability in subsequent years, incremental to market and accounting data. We also document that dividend changes are positively related to earnings changes in each of the two years after the dividend change. It is well documented that dividend changes are positively associated with stock returns in the days surrounding the dividend change announcement (see, e.g., Aharony and Swary (1980), Asquith and Mullins (1983), Kalay and Loewenstein (1985), and Petit (1972)). According to "the information content of dividends hypothesis" (Miller and Modigliani (1961)), dividend changes trigger stock returns because they convey new information about the firm's future profitability. However, recent studies have not supported this hypothesized relation between dividend changes and future earnings (e.g., DeAngelo, DeAngelo, and Skinner (1996), Benartzi, Michaely, and Thaler (BMT, 1997)). We reexamine the relation between dividend changes and alternative measures of future profitability, and provide strong evidence that dividend changes are positively related to future earnings changes, future earnings, and future abnormal earnings. To investigate whether dividend changes convey new information about future profitability, one has to estimate expected profitability. Most prior studies assume that earnings follow a random walk with drift, and measure unexpected profitability as the realized change in earnings minus the estimated drift. They then examine the association between dividend changes and unexpected earnings. We first use a similar approach and find, like prior studies, that dividend changes are not positively related to future earnings changes. We then modify the regression model to address two specifi
Synthesis and Applications of α-Trifluoromethylated Alkylboron Compounds†

The importance of incorporating fluorinated subunits into organic molecules is well established in the pharmaceutical, agrochemical, and materials industries.1,2 Developing methods of incorporating such fluorinated moieties into organic substrates in a safe, selective, and facile manner, therefore, has been an area of great interest.3 Among the various fluorinated moieties, the strongly electron-withdrawing trifluoromethyl group (CF3) has garnered much attention because of the profound properties it can effect upon being implanted within a molecule.4 However, most of the synthetic efforts have been focused on introducing CF3 in functionalized arenes.5
Can peace be purchased? A sectoral-level analysis of aid’s influence on transnational terrorism

Does foreign aid reduce terrorism? We examine whether foreign aid decreases terrorism by analyzing whether aid targeted toward certain sectors is more effective than others. We use the most comprehensive databases on foreign aid and transnational terrorism—AidData and ITERATE—to provide a series of statistical tests. Our results show that foreign aid decreases terrorism especially when targeted toward sectors, such as education, health, civil society, and conflict prevention. These sector-level results indicate that foreign aid can be an effective instrument in fighting terrorism if allocated in appropriate ways.
Salts and Radiation Products on the Surface of Europa

The surface of Europa could contain the compositional imprint of an underlying interior ocean, but competing hypotheses differ over whether spectral observations from the Galileo spacecraft show the signature of ocean evaporates or simply surface radiation products unrelated to the interior. Using adaptive optics at the W. M. Keck Observatory, we have obtained spatially resolved spectra of most of the disk of Europa at a spectral resolution ~40 times higher than seen by the Galileo spacecraft. These spectra show a previously undetected distinct signature of magnesium sulfate salts on Europa, but the magnesium sulfate is confined to the trailing hemisphere and spatially correlated with the presence of radiation products like sulfuric acid and SO_2. On the leading, less irradiated, hemisphere, our observations rule out the presence of many of the proposed sulfate salts, but do show the presence of distorted water ice bands. Based on the association of the potential MgSO_4 detection on the trailing side with other radiation products, we conclude that MgSO_4 is also a radiation product, rather than a constituent of a Europa ocean brine. Based on ocean chemistry models, we hypothesize that, prior to irradiation, magnesium is primarily in the form of MgCl_2, and we predict that NaCl and KCl are even more abundant, and, in fact, dominate the non-ice component of the leading hemisphere. We propose observational tests of this new hypothesis.