cssi/SciSciGPT-SciSciNet huggingface dataset:
The Radio Wavelength Time Delay of Gravitational Lens 0957+561

The gravitational lens 0957+561 was monitored with the Very Large Array from 1979 to 1997. The 6 cm light-curve data from 1995 to 1997 and the 4 cm data from 1990 to 1997 are reported here. At 4 cm the intrinsic source variations occur earlier and are twice as large as the corresponding variations at 6 cm. The VLBI core and jet components have different magnification factors, leading to different flux ratios for the varying and nonvarying portions of the VLA light curves. Using both the Press, Rybicki, & Hewitt Q (PRHQ) and dispersion statistical techniques, we determined the time delay, core flux ratio, and excess nonvarying B image flux density. The fits were performed for the 4 and 6 cm light curves, both individually and jointly, and we used Gaussian Monte Carlo data to estimate 68% statistical confidence levels. The delay estimates from each individual wavelength were inconsistent given the formal uncertainties, suggesting that there are unmodeled systematic errors in the analysis. We roughly estimate the systematic uncertainty in the joint result from the difference between the 6 and 4 cm results, giving 409±30 days for the PRHQ statistic and 397±20 days for the dispersion statistic. These results are consistent with the current optical time delay of 417±3 days, reconciling the long-standing difference between the optical and radio light curves and between different statistical analyses. The unmodeled systematic effects may also corrupt light curves for other lenses, and we caution that multiple events at multiple wavelengths may be necessary to determine an accurate delay in any lens system. Now that consensus has been reached regarding the time delay in the 0957+561 system, the most pressing issue remaining for determining H0 is a full understanding of the mass distribution in the lens.
Uniqueness, Stability, and Comparative Statics in Rationalizable Walrasian Markets ¤

This paper studies the extent to which qualitative features of Walrasian equilibria are refutable given a finite data set. In particular, we consider the hypothesis that the observed data are Walrasian equilibria in which each price vector is locally stable under tâtonnement. Our main result shows that a finite set of observations of prices, individual incomes and aggregate consumption vectors is rationalizable in an economy with smooth characteristics if and only if it is rationalizable in an economy in which each observed price vector is locally unique and stable under ttonnement. Moreover, the equilibrium correspondence is locally monotone in a neighborhood of each observed equilibrium in these economies. Thus the hypotheses that equilibria are locally stable under tâtonnement, equilibrium prices are locally unique and equilibrium comparative statics are locally monotone are not refutable with a finite data set.
The Shielding of CEO Compensation from the Effects of Strategic Expenditures

This study investigates whether and why compensation committees shield CEO compensation from income-decreasing effects of strategic expenditures. We document that firms do shield recurring strategic expenditures such as research and development and advertising expenditures. We also find that firms shield research and development expenditures more than advertising expenditures. Our results are consistent with prior findings that suggest that compensation committees shield CEOs from nonroutine transactions such as restructuring charges and extraordinary losses. Using a two-task principal-agent framework, we show that such shielding improves the efficiency of the contract by making the shielded income measure more congruent with the principal's objectives.
Can Rescheduling Explain the New Jersey Minimum Wage Studies

This paper interprets the New Jersey minimum wage studies of Card and Krueger and their critics, Neumark and Wascher, through a scheduling model. The former found an increase in the number of workers in New Jersey fast-food restaurants after the state minimum wage was increased, while the latter found a decline in the total payroll hours of New Jersey restaurants. The scheduling model predicts that firms will substitute workers for hours per worker after a wage increase, which is consistent with both studies. Evidence from a subset of restaurants that reported both workers and hours data to Neumark and Wascher supports this interpretation. The New Jersey minimum wage appears to have redistributed income effectively to the targeted population by raising wages and reducing weekly hours per worker by just over one hour without causing any job loss.
Increases in moist-convective updraught velocities with warming in radiative-convective equilibrium

The scaling of updraught velocities over a wide range of surface temperatures is investigated in simulations of radiative-convective equilibrium with a cloud-system resolving model. The updraught velocities increase with warming, with the largest fractional increases occurring in the upper troposphere and for the highest percentile updraughts. A plume model approximately reproduces the increases in updraught velocities if the plume environment is prescribed as the mean profile in each simulation while holding the entrainment and microphysical assumptions fixed. Convective available potential energy (CAPE) also increases with warming in the simulations but at a much faster fractional rate when compared with the square of the updraught velocities. This discrepancy is investigated with a two-plume model in which a weakly entraining plume represents the most intense updraughts, and the environment is assumed to adjust so that a more strongly entraining plume has negligible buoyancy. The two-plume model suggests that updraught velocities increase with warming at a lower fractional rate than implied by the CAPE because of the influence of entrainment on both the mean stratification and the updraughts themselves.
Geometrical wake of a smooth flat collimator

A transverse geometrical wake generated by a beam passing through a smooth flat collimator with a gradually varying gap between the upper and lower walls is considered. Based on generalization of the approach recently developed for a smooth circular taper we reduce the electromagnetic problem of the impedance calculation to the solution of two much simpler static problems-a magnetostatic and an electrostatic ones. The solution shows that in the limit of not very large frequencies, the impedance increases with the ratio h/d where h is the width and d is the distance between the collimating jaws. Numerical results are presented for the NLC Post Linac collimator.
Electrolytic fabrication of atomic clock cells

This paper describes an electrolytic method to fill alkali metal into miniature cells made with anodically bonded silicon wafer and Pyrex glass windows
Green vs. green: Measuring the compensation required to site electrical generation windmills in a viewshed

Proponents of wind power note that wind is a green energy source. Yet locating electrical generating windmills has become difficult in some localities because of potential negative externalities. We address why the NIMBY syndrome may arise when choosing site locations by addressing the perceived property rights of a viewshed, the role of compensation in a NIMBY impasse, and how concerns for the environment might lessen the compensation required. We use a willingness to accept framework to measure the compensation required to allow wind generation windmills to be built in the mountains of North Carolina. We find that individuals who perceive wind energy as a clean source of power require less compensation. Those who retire to the mountains or individuals who have ancestors from Watauga County require more compensation to accept windmills in their viewshed. In addition, we find in a bivariate-probit analysis that individuals who are more likely to participate in a green energy program are also more likely to allow electrical generation windmills in their viewshed, suggesting that the green vs. green environmental debate is overstated.
Stabilization of Ordered Zirconium Titanates through the Chemical Substitution of Ti4+by Al3+/Ta5+

The authors have investigated the ZrO[sub 2]-AlTaO[sub 4] system to understand how selected chemical substitutions can be used to control cation-ordering transformations in zirconium titanate based dielectric ceramics. The complete replacement of the Ti content of Zr[sub x]Ti[sub 2[minus]x]O[sub 4] by a coupled Al[sup 3+]/Ta[sup 5+] substitution permits the synthesis of a wide range of isostructural Zr[sub x](Al[sub 0.5]Ta[sub 0.5])[sub 2[minus]x] solid solutions. At high temperatures a disordered [alpha]-PbO[sub 2] type of structure is formed for 0.375 [le] x [le] 1.03. Samples with 0.67 [le] x [le] 1.03 undergo a cation-ordering reaction to a structure in which the a and b axes of the parent disordered cell are doubled. The stabilities of these cation-ordered derivative structures are significantly greater than those of the ordered zirconium titanates. The ordering temperatures are composition dependent with a maximum of 1,393 C occurring for Zr[sub 0.86](Al[sub 0.5]Ta[sub 0.5])[sub 1.14]O[sub 4]. The higher transition temperatures also enhance the kinetics of the ordering transition; whereas the pure zirconium titanates require extended annealing to produce complete cation order, fully ordered Zr[sub x](Al[sub 0.5]Ta[sub 0.5])[sub 2[minus]x]O[sub 4] solid solutions are produced during a normal furnace cool.
Graph evolution: Densification and shrinking diameters

How do real graphs evolve over timeq What are normal growth patterns in social, technological, and information networksq Many studies have discovered patterns in static graphs, identifying properties in a single snapshot of a large network or in a very small number of snapshots; these include heavy tails for in- and out-degree distributions, communities, small-world phenomena, and others. However, given the lack of information about network evolution over long periods, it has been hard to convert these findings into statements about trends over time.Here we study a wide range of real graphs, and we observe some surprising phenomena. First, most of these graphs densify over time with the number of edges growing superlinearly in the number of nodes. Second, the average distance between nodes often shrinks over time in contrast to the conventional wisdom that such distance parameters should increase slowly as a function of the number of nodes (like O(log n) or O(log(log n)).Existing graph generation models do not exhibit these types of behavior even at a qualitative level. We provide a new graph generator, based on a forest fire spreading process that has a simple, intuitive justification, requires very few parameters (like the flammability of nodes), and produces graphs exhibiting the full range of properties observed both in prior work and in the present study.We also notice that the forest fire model exhibits a sharp transition between sparse graphs and graphs that are densifying. Graphs with decreasing distance between the nodes are generated around this transition point.Last, we analyze the connection between the temporal evolution of the degree distribution and densification of a graph. We find that the two are fundamentally related. We also observe that real networks exhibit this type of relation between densification and the degree distribution.
A laboratory study of the velocity structure in an intrusive gravity current

Laboratory experiments were performed in which an intrusive gravity current was observed using shadowgraph and particle tracking methods. The intrusion was generated in a two-layer fluid with a sharp interface by mixing the fluid behind a vertical lock gate and then suddenly withdrawing the gate from the tank. The purpose of the experiments was to determine the structure of the velocity field inside the intrusion and the stability characteristics of the interface. Soon after the removal of the lock gate, the front of the intrusive gravity current travelled at a constant speed close to the value predicted by theory for an energy-conserving gravity current. The observed structure of the flow inside the intrusion can be divided into three regions. At the front of the intrusion there is an energy-conserving head region in which the fluid velocity is nearly uniform with speed equal to the front speed. This is followed by a dissipative wake region in which large billows are present with their associated mixing and in which the fluid velocity is observed to be non-uniform and have a maximum speed approximately 50% greater than the front speed. Behind the wake region is a tail region in which there is very little mixing and the velocity field is nearly uniform with a speed slightly faster than the front speed.
Aggressive Value Prediction on a GPU

To obtain significant execution speedups, GPUs rely heavily on the inherent data-level parallelism present in the targeted application. However, application programs may not always be able to fully utilize these parallel computing resources due to intrinsic data dependencies or complex data pointer operations. In this paper, we explore how to leverage aggressive software-based value prediction techniques on a GPU to accelerate programs that lack inherent data parallelism. This class of applications are typically difficult to map to parallel architectures due to the presence of data dependencies and complex data pointer manipulation present in these applications. Our experimental results show that, despite the overhead incurred due to software speculation and the communication overhead between the CPU and GPU, we obtain up to 6.5 $$\times $$ speedup on a selected set of kernels taken from the SPEC CPU2006, PARSEC and Sequoia benchmark suites.
Managed behavioral health care carve-outs : Past performance and future prospects

As the managed behavioral health care market has matured, behavioral health carve-outs have solved many problems facing the delivery of behavioral health services; at the same time, they have exacerbated existing difficulties or created new problems. Carve-outs developed to address rising inpatient behavioral health costs and limited insurance coverage. They are based on the economic principles of economies of specialization, economies of scale, price negotiation, and selection. Literature shows that carve-outs have been successful in lowering costs and maintaining or improving access, but results on their impact on quality of care are mixed. In recent years, carve-outs have evolved to take on new roles within the health system, such as coordinating mental and physical health, addressing fragmented public financing systems, and using market power to implement quality improvement. Although not perfect, carve-outs have been instrumental in addressing long-standing challenges in utilization, access, and cost of behavioral health care.
Letter to the editor: "Quantifying albumin permeability with multiphoton microscopy: why the difference?"

TO THE EDITOR: Utilizing intravital multiphoton microscopy, Schiesl and Castrop (19) examined glomerular albumin permeability and the effect of angiotensin II. Recent data relating to glomerular albumin permeability and proximal tubule cell albumin handling have renewed the debate regarding the importance of both facets in albuminuria. The utilization of multiphoton microscopy to study this phenomenon has divided the community as initial studies by Russo et al. (13) reported a
On the convergence properties of non-Euclidean extragradient methods for variational inequalities with generalized monotone operators

In this paper, we study a class of generalized monotone variational inequality (GMVI) problems whose operators are not necessarily monotone (e.g., pseudo-monotone). We present non-Euclidean extragradient (N-EG) methods for computing approximate strong solutions of these problems, and demonstrate how their iteration complexities depend on the global Lipschitz or Holder continuity properties for their operators and the smoothness properties for the distance generating function used in the N-EG algorithms. We also introduce a variant of this algorithm by incorporating a simple line-search procedure to deal with problems with more general continuous operators. Numerical studies are conducted to illustrate the significant advantages of the developed algorithms over the existing ones for solving large-scale GMVI problems.
From the Factory to the Playroom: Mattel, Inc.—Shenzhen Union King Sales Contract Exercise

This article presents a contract negotiation exercise is designed to facilitate students’ learning international contracts for the sale of goods, including considering all of the issues that might arise from the factory to the playroom. In this exercise, buyers from Mattel design an 'action figure' and enter into an agreement with Shenzhen Union King Industrial Co., Inc. (Union King) for the manufacture of the dolls at Union King’s facility in Guangdong Province, China. Part I consists of the actual negotiation exercise to be distributed to students. A separate case is provided for the buyers and sellers; students are asked to keep their respective information confidential. This section also contains the assignment, which should be distributed to all buyers and sellers. Part II is the teaching note, setting forth the learning objectives, information about actual administration of the exercise in the classroom and suggested methods of evaluation.
Is foreign direct investment a channel of knowledge spillovers? Evidence from Japan's FDI in the United States

Abstract Recent empirical work has examined the extent to which international trade fosters international “spillovers” of technological information. FDI is an alternate, potentially equally important channel for the mediation of such knowledge spillovers. I introduce a framework for measuring international knowledge spillovers at the firm level, and I use this framework to directly test the hypothesis that FDI is a channel of knowledge spillovers for Japanese multinationals undertaking direct investments in the United States. Using an original firm-level panel data set on Japanese firms' FDI and innovative activity, I find evidence that FDI increases the flow of knowledge spillovers both from and to the investing Japanese firms.
A dictionary-based approach to fast and accurate name matching in large law enforcement databases

In the presence of dirty data, a search for specific information by a standard query (e.g., search for a name that is misspelled or mistyped) does not return all needed information. This is an issue of grave importance in homeland security, criminology, medical applications, GIS (geographic information systems) and so on. Different techniques, such as soundex, phonix, n-grams, edit-distance, have been used to improve the matching rate in these name-matching applications. There is a pressing need for name matching approaches that provide high levels of accuracy, while at the same time maintaining the computational complexity of achieving this goal reasonably low. In this paper, we present ANSWER, a name matching approach that utilizes a prefix-tree of available names in the database. Creating and searching the name dictionary tree is fast and accurate and, thus, ANSWER is superior to other techniques of retrieving fuzzy name matches in large databases.
Brain-computer interface controlled robotic gait orthosis.

Background: Excessive reliance on wheelchairs in individuals with tetraplegia or paraplegia due to spinal cord injury (SCI) leads to many medical co-morbidities, such as cardiovascular disease, metabolic derangements, osteoporosis, and pressure ulcers. Treatment of these conditions contributes to the majority of SCI health care costs. Restoring able-body-like ambulation in this patient population can potentially reduce the incidence of these medical co-morbidities, in addition to increasing independence and quality of life. However, no biomedical solution exists that can reverse this loss of neurological function, and hence novel methods are needed. Brain-computer interface (BCI) controlled lower extremity prostheses may constitute one such novel approach. Methods: One able-bodied subject and one subject with paraplegia due to SCI underwent electroencephalogram (EEG) recordings while engaged in alternating epochs of idling and walking kinesthetic motor imagery (KMI). These data were analyzed to generate an EEG prediction model for online BCI operation. A commercial robotic gait orthosis (RoGO) system (suspended over a treadmill) was interfaced with the BCI computer to allow for computerized control. The subjects were then tasked to perform five, 5-min-long online sessions where they ambulated using the BCI-RoGO system as prompted by computerized cues. The performance of this system was assessed with cross-correlation analysis, and omission and false alarm rates. Results: The offline accuracy of the EEG prediction model averaged 86.30% across both subjects (chance: 50%). The cross-correlation between instructional cues and the BCI-RoGO walking epochs averaged across all subjects and all sessions was 0.812 ± 0.048 (p-value < 10 −4 ). Also, there were on average 0.8 false alarms per session and no omissions. Conclusion: These results provide preliminary evidence that restoring brain-controlled ambulation after SCI is feasible. Future work will test the function of this system in a population of subjects with SCI. If successful, this may justify the future development of BCI-controlled lower extremity prostheses for free overground walking for those with complete motor SCI. Finally, this system can also be applied to incomplete motor SCI, where it could lead to improved neurological outcomes beyond those of standard physiotherapy.
Monte Carlo particle simulation of low-density fluid flow on MIMD supercomputers

Direct simulation Monte Carlo is a well-established technique for modeling low density fluid flows. The parallel implementation of a general simulation which allows for body-fitted grids, particle weighting, and a variety of surface and flow chemistry models is described. The authors compare its performance on a 1024-node nCUBE 2 to a serial version for the CRAY-YMP. Experiences with load-balancing the computation via graph-based heuristics and the newer spectral techniques are also discussed. This is a critical issue, since density fluctuations can create orders-of-magnitude differences in computational loads as the simulation progresses. >
Distributed Amorphous Ramp Construction in Unstructured Environments

We present a model of construction using iterative amorphous depositions and give a distributed algorithm to reliably build ramps in unstructured environments. The relatively simple local strategy for interacting with irregularly shaped, partially built structures gives rise robust adaptive global properties. We illustrate the algorithm in both the single robot and multi-robot case via simulation and describe how to solve key technical challenges to implementing this algorithm via a robotic prototype.
The mad hatter's cocktail party: a social mobile audio space supporting multiple simultaneous conversations

This paper presents a mobile audio space intended for use by gelled social groups. In face-to-face interactions in such social groups, conversational floors change frequently, e.g., two participants split off to form a new conversational floor, a participant moves from one conversational floor to another, etc. To date, audio spaces have provided little support for such dynamic regroupings of participants, either requiring that the participants explicitly specify with whom they wish to talk or simply presenting all participants as though they are in a single floor. By contrast, the audio space described here monitors participant behavior to identify conversational floors as they emerge. The system dynamically modifies the audio delivered to each participant to enhance the salience of the participants with whom they are currently conversing. We report a user study of the system, focusing on conversation analytic results.
Government Partisanship, Labor Organization, and Macroeconomic Performance: A Corrigendum

Alvarez, Garrett and Lange (1991) used cross-national data panel data on the Organization for Economic Coordination and Development nations to show that countries with left governments and encompassing labor movements enjoyed superior economic performance. Here we show that the standard errors reported in that article are incorrect. Reestimation of the model using ordinary least squares and robust standard errors upholds the major finding of Alvarez, Garrett and Lange, regarding the political and institutional causes of economic growth but leaves the findings for unemployment and inflation open to question. We show that the model used by Alvarez, Garrett and Lange, feasible generalized least squares, cannot produce standard errors when the number of countries analyzed exceeds the length of the time period under analysis. Also, we argue that ordinary least squares with robust standard errors is superior to feasible generalized least square for typical cross-national panel studies.
Scheduling time-critical instructions on RISC machines

We present a polynomial time algorithm for constructing a minimum completion time schedule of instructions from a basic block on RISC machines such as the Sun SPARC, the IBM 801, the Berkeley RISC machine, and the HP Precision Architecture. Our algorithm can be used as a heuristic for RISC processors with longer pipelines, for which there is no known optimal algorithm. Our algorithm can also handle time-critical instructions, which are instructions that have to be completed by a specific time. Time-critical instructions occur in some real-time computations, and can also be used to make shared resources such as registers quickly available for reuse. We also prove that in the absence of time-critical constraints, a greedy scheduling algorithm always produces a schedule for a target machine with multiple identical pipelines that has a length less than twice that of an optimal schedule. The behavior of the heuristic is of interest because, as we show, the instruction scheduling problem becomes NP-hard for arbitrary length pipelines, even when the basic block of code being input consists of only several independent streams of straightline code, and there are no time-critical constraints. Finally, we prove that the problem becomes NP-hard even for small pipelines, no time-critical constraints, and input of several independent streams of straightline code if either there is only a single register or if no two instructions are allowed to complete simultaneously because of some shared resource such as a bus.
A language for software variation research

Variation occurs in many places in software engineering and takes quite different forms. Software can have different versions, and it can come in different configurations. Software can offer different sets of features, and it can appear in different stages of refactoring without any visible effect in functionality. Traditionally, all these forms of variation have used different representations.While this specialization might have some benefits by facilitating the tailoring to the specific needs of one form of variation, it has also some serious drawbacks. First, different representations prevent or complicate a potential integration of different forms of variation. For example, variation in functionality is currently only poorly supported in most versioning tools by branching. Second, it can be difficult to transfer research results achieved within one representation to other representations. Finally, different representations can lead to duplicated work and a balkanization of variation research efforts.
Charitable giving when altruism and similarity are linked

Abstract This paper presents a model in which anonymous charitable donations are rationalized by two human tendencies drawn from the psychology literature. The first is people's disproportionate disposition to help those they agree with while the second is the dependence of peoples' self-esteem on the extent to which they perceive that others agree with them. Government spending crowds out the charity that ensues from these forces only modestly. Moreover, people's donations tend to rise when others donate. In some equilibria of the model, poor people give little because they expect donations to come mainly from richer individuals. In others, donations by poor individuals constitute a large fraction of donations and this raises the incentive for poor people to donate. The model provides interpretations for episodes in which the number of charities rises while total donations are stagnant.
The Expanding Use of DNA in Law Enforcement: What Role for Privacy?

DNA identification is being used in ever-widening ways, including databases of greater scope, familial and lowstringency searches, and DNA dragnets. After examining the law enforcement and privacy interests, the article concludes that forensic DNA uses must be consistent with privacy and civil liberties.
Charge-coupled devices for memory applications

Since the invention of charge-coupled devices (CCD) in late 1969, the potential of the charge-coupling concept for digital memory has been recognized. Applications to image sensing and signal processing requirements have, however, preceded the application of CCD to memory. This occurred because relatively simple charge-coupled devices offered new performance potentials for image sensing and signal processing. Nonetheless, the basic shift-register nature of CCD implies that its greatest opportunity for widespread application lies in the highly competitive area of high density semiconductor memory. Today, sophisticated CCD memory components are emerging.
Light stop NLSPs at the Tevatron and LHC

How light can the stop be given current experimental constraints? Can it still be lighter than the top? In this paper, we study this and related questions in the context of gauge-mediated supersymmetry breaking, where a stop NLSP decays into a W, b and gravitino. Focusing on the case of prompt decays, we simulate several existing Tevatron and LHC analyses that would be sensitive to this scenario, and find that they allow the stop to be as light as 150 GeV, mostly due to the large top production background. With more data, the existing LHC analyses will be able to push the limit up to at least 180 GeV. We hope this work will motivate more dedicated experimental searches for this simple scenario, in which, for most purposes, the only free parameters are the stop mass and lifetime.
The challenge of establishing world-class universities

Governments are becoming increasingly aware of the important contribution that high performance, world-class universities make to global competitiveness and economic growth. There is growing recognition, in both industrial and developing countries, of the need to establish one or more world-class universities that can compete effectively with the best of the best around the world. Contextualising the drive for world-class higher education institutions and the power of international and domestic university rankings, this book outlines possible strategies and pathways for establishing globally competitive universities and explores the challenges, costs, and risks involved. Its findings will be of particular interest to policy makers, university leaders, researchers, and development practitioners.
Solution chemistry of arsenic selenides : synthesis, spectroscopy and the X-ray structures of [PPh4]2[AsnSe6], n=2,4

Abstract As4Se4 and As4Se3 do not retain their solid-state structures in solution. Dissolution of As4Se4 in en/DMF (en = ethylenediamine, DMF = dimethylformamide) causes the cleavage of an AsAs bond and the formation of the As4Se62− anion. In the presence of excess polyselenide ions the remaining AsAs bond also breaks and the As2Se62− anion is produced. Reduction of As4Se4 by potassium in DMF in the presence of PPH4Cl also produces the As4Se62− anion. [PPh4]2[As4Se6] crystallizes (− 120°C) in the orthorhombic space group Pbca with cell dimensions a = 11.272(1), b = 19.817(2), c = 43.958(9) A, Z = 8. The As4Se62− anion resembles a basket with AsSe exocyclic bonds being the handles. [PPh4]2[As2Se6] crystallizes in the monoclinic space group P21/n with cell constants a = 10.817(2), b = 13.690(4), c = 16.298(3) A, β = 93.96(2)°, Z = 2. The As2Se62− ion has an As2Se4 ring in a trans-chair conformation with a terminal selenium atom on each arsenic atom.
Incentives to Improve Teaching : Lessons from Latin America

This book a collection of chapters is about one of the most pressing challenges in improving education quality in Latin America : designing and implementing effective incentives for enhancing teaching practice as a means for raising student learning outcomes. By providing well-researched evidence on diverse education reforms affecting teacher incentives in the region, the book makes an important contribution to the literature on teacher incentives in general and, especially, to the education literature in Latin America. Incentives to improve teaching : lessons from Latin America focuses on the impact of education reforms that alter teacher incentives on teaching quality and student learning. The reforms explored in this book represent efforts by several countries in the region to increase teacher accountability and introduce incentives to motivate teachers to raise students learning. These efforts will be of interest to readers in governmental agencies, nongovernmental organizations, research institutions and universities. Finally, the authors state, that ensuring all children have the opportunity to learn critical skills at the primary and secondary level is paramount to overcoming the barriers that perpetuate underdevelopment and poverty.
Classical stability of the Galileon

We consider the classical equations of motion for a single Galileon eld with generic parameters in the presence of non-relativistic sources. We introduce the concept of absolute stability of a theory: if one can show that a eld at a single point | like innity for instance | in spacetime is stable, then stability of the eld over the rest of spacetime is guaranteed for any positive energy source conguration. The Dvali-Gabadadze-Porrati (DGP) model is stable in this manner, and previous studies of spherically symmetric solu- tions suggest that certain classes of the single eld Galileon (of which the DGP model is a subclass) may have this property as well. We nd, however, that when general solutions are considered this is not the case. In fact, when considering generic solutions there are no choices of free parameters in the Galileon theory that will lead to absolute stability except the DGP choice. Our analysis indicates that the DGP model is an exceptional choice among the large class of possible single eld Galileon theories. This implies that if general solutions (non-spherically symmetric) exist they may be unstable. Given as- trophysical motivation for the Galileon, further investigation into these unstable solutions may prove fruitful.
Large-Area Nanoscale Patterning: Chemistry Meets Fabrication

This Account describes a new paradigm for large-area nanoscale patterning that combines bottom-up and top-down approaches, merging chemistry with fabrication. This hybrid strategy uses simple nanofabrication techniques to control the alignment, size, shape, and periodicity of nanopatterns and chemical methods to control their materials properties and crystallinity. These tools are highly flexible and can create surface-patterned nanostructures with unusual properties and free-standing nanostructures that are multifunctional and monodisperse. The unprecedented scientific and technological opportunities enabled by nanoscale patterning over wafer-sized areas are discussed.
Improvements to Current Switching

Diode switching circuits have been used in conjunction with emitter followers and current switching circuits to evolve a new set of system building blocks. These blocks exhibit typical delays under five millimicroseconds. Diodes cost less and are physically smaller than transistors; therefore, this new system is cheaper and faster than an all-current switching system and permits at least a fivefold increase in packaging density.
An efficient sequential linear quadratic algorithm for solving nonlinear optimal control problems

We develop a numerically efficient algorithm for computing controls for nonlinear systems that minimize a quadratic performance measure. We formulate the optimal control problem in discrete-time, but many continuous-time problems can be also solved after discretization. Our approach is similar to sequential quadratic programming for finite-dimensional optimization problems in that we solve the nonlinear optimal control problem using sequence of linear quadratic subproblems. Each subproblem is solved efficiently using the Riccati difference equation. We show that each iteration produces a descent direction for the performance measure, and that the sequence of controls converges to a solution that satisfies the well-known necessary conditions for the optimal control.
The inverse Stefan problem for the heat equation in two space variables

Abstract : In this paper the author outlines an inverse method for constructing analytic solutions to the (single phase) Stefan problem for the heat equation in two space dimensions.
Integral extensions and the a-invariant

In this note we compare the a-invariant of a homogeneous algebra B to the a-invariant of a subalgebra A. In particular we show that if A⊂B is a finite homogeneous inclusion of standard graded domains over an algebraically closed field with A normal and B of minimal multiplicity then A has minimal multiplicity. In some sense these results are algebraic generalizations of Hurwitz type theorems.
Systemic failures: Challenges and opportunities in risk management in complex systems

T he BP Deepwater Horizon oil spill disaster has reminded us, once again, the fragility of complex engineered systems. We have been here before but we do not seem to have learnt all the important lessons yet. This is a Santayana moment — ‘‘Those who cannot learn from the past are condemned to repeat it!’’ In the history of chemical plant accidents, a few disasters have served as wake up calls. The Flixborough accident in the U.K. in 1974, where a Nypro plant explosion killed 26 people, was one such call. The worst was Union Carbide’s Bhopal Gas tragedy, in 1984, in which some 5000–25,000 were killed, and about 120,000–500,000 were seriously injured by the accidental release of methyl isocynate (Jasanoff, 1994). Another important one was Piper Alpha, an offshore oil platform operated by Occidental Petroleum in the North Sea, U.K., which exploded in 1988 killing 167 people and resulted in about $2 billion losses (Piper Alpha, 2005). Even though the human casualties were low, this list would also include the 1989 Exxon Valdez oil spill and, now, the BP oil spill, both of which are very serious from an environmental damages perspective. Such systemic failures are not limited to the chemical and petrochemical industries alone. The Northeast electrical power blackout (Fox-Penner, 2004; LaPedis, 2004) and Schering Plough’s inhalers recall (Simons, 2002) are systemic failures. Financial disasters such as Enron, WorldCom, subprime mortgage derivatives market (Plotz, 2002; Johnson and Neave, 2007), Madoff Ponzi scheme (Markopolos, 2010), as well as some other events also belong to the same class (see Table 1). While these are different disasters that happened in different domains, in different facilities, triggered by different events, involve different ingredients, and so on, there are, however, certain common underlying patterns behind such systemic failures. There is an alarming sameness about such major accidents, which underscores important fundamental lessons that need to be learned in order to prevent such events from recurring. To understand these patterns and learn from them, one needs to go beyond analyzing them as independent one-off accidents, and examine them in the broader perspective of the potential fragility of all complex engineered systems. One needs to study all these disasters from a common systems engineering perspective, so that one can thoroughly understand the commonalities as well as the differences, in order to better design and control such systems in the future. Furthermore, such studies need to be carried out in concert with public policy experts, so that all the scientific and engineering lessons get translated into effective policies and regulations. All these have important implications for process systems engineering research and teaching, as outlined in this perspective article.
Performance Test of Wireless Technologies for Personnel and Equipment Proximity Sensing in Work Zones

AbstractThe dynamic nature and limited work space of roadway work zones contribute to dangerous working environments for construction workers. This environment can result in hazardous proximity sit...
An efficient algorithm for Chinese postman walk on bi-directed de Bruijn graphs

Sequence assembly from short reads is an important problem in biology. It is known that solving the sequence assembly problem exactly on a bi-directed de Bruijn graph or a string graph is intractable. However finding a Shortest Double stranded DNA string (SDDNA) containing all the k-long words in the reads seems to be a good heuristic to get close to the original genome. This problem is equivalent to finding a cyclic Chinese Postman (CP) walk on the underlying unweighted bi-directed de Bruijn graph built from the reads. The Chinese Postman walk Problem (CPP) is solved by reducing it to a general bi-directed flow on this graph which runs in O(|E|2 log2(|V|)) time. In this paper we show that the cyclic CPP on bi-directed graphs can be solved without reducing it to bi-directed flow. We present a Θ(p(|V|+|E|) log(|V|)+(dmaxp)3) time algorithm to solve the cyclic CPP on a weighted bi-directed de Bruijn graph, where p = max{|{v|din(v) - dout(v) > 0}|,|{v|din(v) - dout(v) < 0}|} and dmax = max{|din(v) - dout(v)}. Our algorithm performs asymptotically better than the bi-directed flow algorithm when the number of imbalanced nodes p is much less than the nodes in the bi-directed graph. From our experimental results on various datasets, we have noticed that the value of p/|V| lies between 0.08% and 0.13% with 95% probability. Many practical bi-directed de Bruijn graphs do not have cyclic CP walks. In such cases it is not clear how the bi-directed flow can be useful in identifying contigs. Our algorithm can handle such situations and identify maximal bi-directed sub-graphs that have CP walks. We also present a Θ((|V| + |E|) log(V)) time algorithm for the single source shortest path problem on bi-directed de Bruijn graphs, which may be of independent interest.
Resolution enhancement of 157 nm lithography by liquid immersion

We present the results of a preliminary feasibility study of liquid immersion lithography at 157 nm. A key enabler has been the identification of a class of commercially available liquids, perfluoropolyethers, with low 157 nm absorbance α157 ∼ 10 cm−1 base 10. With 157 nm index of refraction around 1.36, these liquids could enable lithography at numerical aperture ∼1.25 and thus resolution of 50 nm for k1 = 0.4. We have also performed preliminary studies on the optical, chemical, and physical suitability of these liquids for use in high throughput lithography. We also note that at longer wavelengths, there is a wider selection of transparent immersion liquids. At 193 nm, the most transparent liquid measured, de-ionized water, has α193 = 0.036 cm−1 base 10. Water immersion lithography at 193 nm would enable resolution of 60 nm with k1 = 0.4.
A multimodal learning interface for grounding spoken language in sensory perceptions

We present a multimodal interface that learns words from natural interactions with users. In light of studies of human language development, the learning system is trained in an unsupervised mode in which users perform everyday tasks while providing natural language descriptions of their behaviors. The system collects acoustic signals in concert with user-centric multisensory information from nonspeech modalities, such as user's perspective video, gaze positions, head directions, and hand movements. A multimodal learning algorithm uses this data to first spot words from continuous speech and then associate action verbs and object names with their perceptually grounded meanings. The central ideas are to make use of nonspeech contextual information to facilitate word spotting, and utilize body movements as deictic references to associate temporally cooccurring data from different modalities and build hypothesized lexical items. From those items, an EM-based method is developed to select correct word--meaning pairs. Successful learning is demonstrated in the experiments of three natural tasks: "unscrewing a jar," "stapling a letter," and "pouring water."
Development of an XSPEc-based spectral analysis system for the coded-aperture hard X-ray balloon payload EXITE2

Abstract We present the spectral analysis system for the second-generation energetic X-ray imaging telescope experiment (EXITE2) balloon payload. EXITE2 is an imaging hard X-ray telescope using a coded-aperture mask and a NaI/CsI phoswich detector operating in the energy range 20–600 keV. The instrument was flown on a high-altitude scientific balloon from Ft. Sumner, NM on 7–8 May, 1997. We describe the details of the EXITE2 spectral analysis system, with emphasis on those aspects peculiar to coded-aperture instruments. In particular, we have made our analysis compatible with the standard X-ray spectral fitting package xspec by generating a response matrix in the appropriate format including all the effects of a coded-aperture system. The use of xspec , which may be a first for coded-aperture data, permits great flexibility in the fitting of spectral models. The additional effects of our phoswich system, or any other detector-specific considerations, may be easily included as well. We test our spectral analysis using observations of the Crab Nebula, and find that the EXITE2 Crab spectrum is consistent with those recorded by previous instruments operating in this energy range.
On the development of a higher-order PML

A new formulation based on stretched coordinates is developed for perfectly matched layers (PML). The new PML can have multiple poles in contrast to the regular PML with a single pole. The implementation is also derived and the preliminary results are shown to be better than the regular PML with insignificant increase in the computational cost
Ambidexterity and Performance in Small- to Medium-Sized Firms: The Pivotal Role of Top Management Team Behavioral Integration.

While a firm’s ability to jointly pursue both an exploitative and exploratory orientation has been posited as having positive performance effects, little is currently known about the antecedents and consequences of such ambidexterity in small-to medium-sized firms (SMEs). To that end, this study focuses on the pivotal role of top management team (TMT) behavioral integration in facilitating the processing of disparate demands essential to attaining ambidexterity in SMEs. Then, to address the bottom-line importance of an ambidextrous orientation, the study hypothesizes its association with relative firm performance. Multisource survey data, including CEOs and TMT members from 139 SMEs, provide support for both hypotheses.