cssi/SciSciGPT-SciSciNet huggingface dataset:
Optimized Low-Thrust Missions from GTO to Mars

A small spacecraft has three primary methods to get to Mars: by a dedicated launch vehicle, by sharing a ride with another Mars-bound mission, or via rideshare to Earth orbit and making its own way to the Red Planet. The third option may be the most attractive in terms of cost effectiveness and frequency of access, which are the main drawbacks of the first two, respectively. In the past 5 years, over 50 satellites have been launched from U.S. soil en route to geosynchronous orbit and beyond. Many of these launches do not use the full capability of the launch vehicle, leaving an opportunity for a small secondary spacecraft to get a ride to geosynchronous transfer orbit (GTO). Starting from an ESPA-ring rideshare to GTO, a solar-electric propulsion (SEP) powered spacecraft can make its own way to Mars orbit to perform a useful mission. In this paper, we explore the mission design space for small, ESPA-class (200–450 kg) spacecraft transferring from GTO to Mars orbit. This is accomplished by creating tools that jointly optimize low-thrust trajectories and spacecraft subsystems to create feasible mission concepts. An example is given of an Areostationary telecom orbiter that reaches Mars in 2 years with a dry mass of 200 kg.
Is There a Role for Desensitization in Intestinal Transplantation

Human leukocyte antigen allosensitization prior to transplant can increase the risk of early graft loss and prolong waitlist times for intestinal transplant candidates. Desensitization offers a potential therapeutic option to reduce the quantity of preformed antibodies prior to organ allocation and facilitate transplantation with a more immunologically compatible donor allograft. However, there remains a paucity of data to guide the use of desensitization in the setting of intestinal transplantation. As a result, in this review we evaluate the existing literature supporting the role of desensitization therapy in intestinal transplant, describe our own experience with the implementation of a risk-stratified desensitization protocol, and finally explore barriers and unanswered questions that continue to limit the widespread adoption of desensitization as a management strategy for highly sensitized intestinal transplant candidates.
Transnational Friendships and Fluid Boundaries in Early Childhood Classrooms: The Possibilities of (Un)Productive Play in Teacher–Researcher Collaborations for Equity:

Drawing from transnational feminism, we describe the interplay of multiple identities influencing teaching and research. By exploring our stories of border crossing as first/second-generation immig...
Dose to Highly Functional Ventilation Zones Improves Prediction of Radiation Pneumonitis for Proton and Photon Lung Cancer Radiation Therapy.

Purpose We hypothesized that the radiation dose in high-ventilation portions of the lung better predicts radiation pneumonitis (RP) outcome for patients treated with proton radiation therapy (PR) and photon radiation therapy (PH). Methods and Materials Seventy-four patients (38 protons, 36 photons) with locally advanced non-small cell lung cancer treated with concurrent chemoradiation therapy were identified, of whom 24 exhibited RP (graded using Common Terminology Criteria for Adverse Events v4.0) after PR or PH, and 50 were negative controls. The inhale and exhale simulation computed tomography scans were deformed using Advanced Normalization Tools. The 3-dimensional lung ventilation maps were derived from the deformation matrix and partitioned into low- and high-ventilation zones for dosimetric analysis. Receiver operating curve analysis was used to study the power of relationship between RP and ventilation zones to determine an optimal ventilation cutoff. Univariate logistic regression was used to correlate dose in high- and low-ventilation zones with risk of RP. A nonparametric random forest process was used for multivariate importance assessment. Results The optimal high-ventilation zone definition was determined to be the higher 45% to 60% of the ventilation values. The parameter vV20Gy_high (high ventilation volume receiving ≥20 Gy) was found to be a significant indicator for RP (PH: P = .002, PR: P = .035) with improved areas under the curve compared with the traditional V20Gy for both photon and proton cohorts. The relationship of RP with dose to the low-ventilation zone of the lung was insignificant (PH: P = .123, PR: P = .661). Similar trends were observed for ventilation mean lung dose and ventilation V5Gy. Multivariate importance assessment determined that vV20Gy_high, vV5_high, and mean lung dose were the most significant parameters for the proton cohort with a combined area under the curve of 0.78. Conclusion Dose to the high-ventilated regions of the lung can improve predictions of RP for both PH and PR.
Natural supersymmetry: status and prospects

The realization that supersymmetry (SUSY), if softly broken at the weak scale, can stabilize the Higgs sector led many authors to explore the role it may play in particle physics. It was widely anticipated that superpartners would reveal themselves once the TeV scale was probed in high energy collisions. Experiments at the LHC have not yet revealed any sign for direct production of superpartners, or for any other physics beyond the Standard Model. This has led to some authors to question whether weak scale SUSY has a role to play in stabilizing the Higgs sector, and to seek alternate mechanisms for stabilizing the weak scale. We reevaluate the early arguments that led to the expectations for light superpartners, and show that SUSY models with just the minimal particle content may well be consistent with LHC (and other) data and simultaneously serve to stabilize the Higgs sector, if model parameters generally regarded as independent turned out to be appropriately correlated. In our view, it would be premature to ignore this possibility, given that we do not understand the underlying mechanism of SUSY breaking. We advocate using the electroweak scale quantity, ΔEW, to determine whether a given SUSY spectrum might arise from a theory with low fine-tuning, even when the parameters correlations mentioned above are present. We find that (modulo technical caveats) all such models contain light higgsinos and that this leads to the possibility of new strategies for searching for SUSY. We discuss phenomenological implications of these models for SUSY searches at the LHC and its luminosity and energy upgrades, as well as at future electron-positron colliders. We conclude that natural SUSY, defined as no worse than a part in 30 fine-tuning, will not escape detection at a pp collider operating at 27 TeV and an integrated luminosity of 15 ab−1, or at an electron-positron collider with a centre-of-mass energy of 600 GeV.
Abstract TMP78: Heterogeneous Imaging Practices Associated With Emergency Department Work-Up of Transient Ischemic Attack

Introduction: Multiple societal guidelines recommend urgent imaging in patients with transient ischemic attack (TIA) to identify and treat risk factors that may lead to future stroke. Recommended s...
P5 The Baltimore Urban Food Distribution (BUD) Pilot Study: A Food Systems Intervention Leveraging Technology and Community-Based Strategies

Background Under-resourced urban communities in the United States commonly lack access to healthy foods, largely due to a food system that favors the provision of calorie-dense processed foods to main food sources. The Baltimore Urban food Distribution (BUD) study is a multi-level, multi-component systems intervention that leverages technology to move fresh foods from local suppliers to corner stores located in food-scarce neighborhoods of Baltimore, Maryland. Objective To develop, pilot test, and evaluate the BUD application (app) among 1 producer and 2-3 corner stores. Study Design, Setting, Participants Formative research to design the BUD app began in 2016 and is ongoing. We will recruit 2-3 corner stores to participate in a first-round pilot test. These stores will receive subsidized kale and mustard greens through in-app purchasing and delivery directly from the supplier between May 1-July 31, 2021. Point-of-purchase marketing strategies (shelf-talkers, recipe cards, display cases) will increase consumer awareness and demand. Adobe Photoshop, Illustrator, and XD will aid in the design of the app user interface. Google Firebase will ensure security of in-app purchasing and data tracking. Measurable Outcome/Analysis This first-round pilot test will be evaluated pre- and post-intervention at the supplier- and retailer-levels using structured impact questionnaires, and open-ended questions. Quantitative analyses will assess number of promoted items ordered, stocked, and sold biweekly, and daily app usage, captured in-app. Results Stakeholders (n = 27) at multiple levels of the food system found a prototype of the app to have high feasibility for use, demonstrating particular support for collective purchasing and delivery. This pilot test will further identify psychosocial changes, biweekly stocking and sales data, daily app usage, and key challenges and strengths of the app. Conclusion BUD uniquely intervenes at multiple levels of the local food system. This first-round pilot test will inform a randomized controlled trial set to begin in Fall 2021 among a sample of 38 corner stores.
Profiling atmospheric turbulence along a slant path using LEDs and a camera bank

Understanding how atmospheric turbulence is distributed along a path helps in effective turbulence compensation and mitigation. Phase-based techniques to measure turbulence have potential advantages when used over long ranges since they do not suffer from saturation issues as the irradiance-based techniques. In an earlier work, we had demonstrated a method to extract turbulence information along a path using the time-lapse imagery of a LED array from a pair of spatially separated cameras. By measuring the differential motion of pairs of LEDs of varying separations, sensed by a single camera or between cameras, turbulence profiles could be obtained. However, by using just a pair of cameras, the entire path could not be profiled. By using multiple spatially separated cameras, improvements can be made on the profiling resolution as well as the fraction of the path over which profiling is possible. This idea has been demonstrated in the present work by using a camera bank comprising of 5 identical cameras, looking at an arrangement of 10 nonuniformly spaced LEDs over a slant path. The differential tilt variances measured at a single camera and between all pairs of cameras have been used to obtain turbulence information. Profiling thus with elevated targets will ultimately help in a better understanding of how turbulence varies with altitude in the surface layer.
Focusing and Accelerating Light with the Same Flat Lens

We demonstrate how a simple 1D flat lens can be utilized to not only focus light but to generate non-paraxial accelerating beams. We further report how illumination angle and wavelength degrees of freedom allow dynamic transition between these two functionalities.
#NeuroTwitter 101: a tweetorial on creating tweetorials.

When the COVID-19 pandemic reduced opportunities for inperson learning for students, residents and fellows, many neurologists turned to online learning modalities such as podcasts, webinars and social media platforms like Twitter.1–4 The ‘Tweetorial’ (a hybridisation of the words ‘tweet’ and ‘tutorial’) recently emerged as a way …
Censored exploration and the Dark Pool Problem

We introduce and analyze a natural algorithm for multi-venue exploration from censored data, which is motivated by the Dark Pool Problem of modern quantitative finance. We prove that our algorithm converges in polynomial time to a near-optimal allocation policy; prior results for similar problems in stochastic inventory control guaranteed only asymptotic convergence and examined variants in which each venue could be treated independently. Our analysis bears a strong resemblance to that of efficient exploration/exploitation schemes in the reinforcement learning literature. We describe an extensive experimental evaluation of our algorithm on the Dark Pool Problem using real trading data.
Mechanisms of Nickel Catalyst Poisoning

Abstract Poisoning, the strong chemisorption of reactants, products or impurities on active catalytic sites, is an important, difficult deactivation problem in many catalytic processes and particularly in processes involving nickel catalysts. For example, only a few ppm of sulfur impurities can reduce the activity of nickel methanation catalysts by several orders of magnitude within just a few days or weeks; moreover the sulfur thus adsorbed is essentially irreversibly held and cannot be conveniently removed by treatments with air, oxygen, steam, or hydrogen. Catalyst poisons for nickel can be classified according to chemical species, types of reactions poisoned, and selectivity for active catalyst sites. For example, sulfur in the form of H2S and organic sulfides is a highly selective, strongly adsorbing poison for nickel hydrogenation, methanation, and steam reforming catalysts. That surface sulfur-nickel bonds are substantially more stable than the corresponding bulk nickel-sulfur bonds is emphasized by the fact that hydrogen sulfide adsorbs dissociatively with a heat of 250 kJ/mole compared to a heat of bulk formation of 75 kJ/mole. Adsorbed sulfur blocks the adsorption of most other species and generally causes a substantial or complete loss of nickel catalyst activity. Whether this loss of activity is a geometric blocking or a longer range electronic effect is somewhat controversial and probably depends on coverage. The evidence is in favor of a combination of geometric and electronic effects at low sulfur coverages and geometric blocking effects at high coverages. The toxicity of poisons for nickel depends on the stability of the nickel-additive bond as well as the electronegativity of the adsorbing species. Species with a high degree of shielding such as SO3 are less toxic than poorly shielded species such as elemental sulfur and H2S. The toxicity of some poisons, e. g. carbonaceous species, depends not only on their strength of adsorption but also on their reactivity with gasifying agents such as hydrogen or water vapor.
Fast belief update using order-of-magnitude probabilities

We present an algorithm, called Predict, for updating beliefs in causal networks quantified with order-of-magnitude probabilities. The algorithm takes advantage of both the structure and the quantification of the network and presents a polynomial asymptotic complexity. Predict exhibits a conservative behavior in that it is always sound but not always complete. We provide sufficient conditions for completeness and present algorithms for testing these conditions and for computing a complete set of plausible values. We propose Predict as an efficient method to estimate probabilistic values and illustrate its use in conjunction with two known algorithms for probabilistic inference. Finally, we describe an application of Predict to plan evaluation, present experimental results, and discuss issues regarding its use with conditional logics of belief, and in the characterization of irrelevance.
The Blinding Color of Race: Elections and Democracy in the Post-Shelby County Era

Racial minorities are registering to vote and turning out at the ballot box in record numbers.1 Nevertheless, they remain under-represented in local elected positions and virtually excluded from national and state political positions.2 Latinos, for example, are the largest racial minority in the U.S. at approximately 17% of the population,3 but only 3.3% of elected political positions are held by Latinos.4 In states that the VRA until recently covered, such as Texas, Alabama, Mississippi, and Louisiana, African Americans held 11 %, 25%, 30%, and 18%5 of elected positions, respectively; although the
Free Probability for Pairs of Faces IV: Bi-free Extremes in the Plane

We compute the bi-free max-convolution which is the operation on bivariate distribution functions corresponding to the max-operation with respect to the spectral order on bi-free bipartite two-faced pairs of Hermitian non-commutative random variables. With the corresponding definitions of bi-free max-stable and max-infinitely divisible laws, their determination becomes in this way a classical analysis question.
FROM COLD TO HOT: A PRELIMINARY ANALYSIS OF CLIMATIC EFFECTS ON THE PRODUCTIVITY OF WISCONSIN DAIRY FARMS

This study examines the effect of climatic variables on dairy farm productivity using panel data for the state of Wisconsin along with alternative stochastic frontier models. A noteworthy feature of this analysis is that Wisconsin is a major dairy producing area where winters are typically very cold and snowy, and summers hot and humid. Thus, it is an ideal geographical region for examining the effects of a range of climatic factors on dairy production. This paper presents a preliminary analysis of the climatic effect on the productivity of Wisconsin farms. We identify the effect of temperature and precipitation, both jointly and separately, on milk output. The analysis shows that increasing temperature in summer or in autumn is harmful for dairy production, while warmer winters and warmer springs are beneficial. By contrast, more precipitation has a consistent adverse effect on dairy productivity. Overall, in the past 17 years, climatic conditions have had a negative impact on the dairy farms in Wisconsin and the data reveals a mild negative trend.
A Scalable Algorithm for Radiative Heat Transfer Using Reverse Monte Carlo Ray Tracing

Radiative heat transfer is an important mechanism in a class of challenging engineering and research problems. A direct all-to-all treatment of these problems is prohibitively expensive on large core counts due to pervasive all-to-all MPI communication. The massive heat transfer problem arising from the next generation of clean coal boilers being modeled by the Uintah framework has radiation as a dominant heat transfer mode. Reverse Monte Carlo ray tracing (RMCRT) can be used to solve for the radiative-flux divergence while accounting for the effects of participating media. The ray tracing approach used here replicates the geometry of the boiler on a multi-core node and then uses an all-to-all communication phase to distribute the results globally. The cost of this all-to-all is reduced by using an adaptive mesh approach in which a fine mesh is only used locally, and a coarse mesh is used elsewhere. A model for communication and computation complexity is used to predict performance of this new method. We show this model is consistent with observed results and demonstrate excellent strong scaling to 262 K cores on the DOE Titan system on problem sizes that were previously computationally intractable.
Fines Under New Federal Civil Rule 11: The New Monetary Sanctions for the "Stop-and-Think-Again" Rule

The 1983 amendments to Federal Rule of Civil Procedure Rule 11, which dealt with frivolous litigation papers, prompted much controversy, satellite litigation, and a new cottage industry, Rule amendments in 1983 increased both the range of sanctionable attorney conduct and the extent of judicial sanctionable authority. By the latter 1980s, many concluded that further amendments were warranted. Case law, commentary and empirical research culminated in a new rule which took effect in December, 1993. In part, the 1993 Rule reduces a party's incentives to pursue sanctions for frivolous papers since less misconduct will be sanctionable. Further, attorney's fees will be less available as a sanction even when a violation occurs. Other forms of sanctions, such as a fine payable to the court, will be employed. These new forms raise very different questions than did the most common form of sanction under the 1983 Rule-an award of attorney's fees. Although both fines and fees constitute monetary sanctions, fines are usually ordered with the public interest in mind. Fees are awarded, at least in significant part, to promote private interests. The move from fees to fines presents new challenges for those governed by Rule 11. This article reviews fines under the 1993 Rule, finding that the new rule may best be characterized as "Big-Brother-Says-Stop-and-Think-Again" rule-quite distinct from the "Stop-and-Think" rule of 1983.
Organocatalytic Synthesis of Alkynes

Carbon–carbon triple bonds of alkynes are ubiquitous. They serve as valuable starting materials that can be transformed into a vast array of diverse materials, with applications ranging from medicinal chemistry to electronic materials. The methods used to prepare alkynes involve stoichiometric reactions and the most popular install only a single carbon rather than uniting larger fragments. These methods are useful, but they are limited by harsh conditions or the need to prepare reagents. Introduced herein is the first catalytic method to prepare carbon–carbon triple bonds from precursors that do not contain such linkages. By coupling benzaldehyde and benzyl chloride derivatives under basic conditions with an organocatalyst, good yields of alkynes are obtained. The catalyst, a highly reactive sulfenate anion, is readily generated under the reaction conditions from air-stable precursors. This method represents an attractive organocatalytic alternative to well-established stoichiometric approaches to alkynes...
Variations on Kuratowski's 14-Set Theorem

Apparently Question 1.2 will require us to solve 25 = 32 different problems . . . well, not really. Many of these are redundant, either because different choices of I allow us to perform the same operations, or because different choices of I raise algebraically isomorphic questions. (This is explained in Section 4.) Theorem 1.1 answers at least one case, and certainly many others are trivial. Finally, an example of Kuratowski shows that if we allow all five operations, we may obtain infinitely many sets. After a full reckoning, only two questions remain.
Financial Openness, Democracy, and Redistributive Policy

The debate about the relationship between democratic forms of government and the free movement of capital across borders dates to the 18th century. It has regained prominence as capital on a massive scale has become increasingly mobile and as free economies experience continuous pressure from rapidly changing technology, market integration, changing consumer preferences, and intensified competition. These changes imply greater uncertainty about citizens' future income positions, which could prompt them to seek insurance through the marketplace or through constitutionally arranged income redistribution. As more countries move toward democracy, the availability of such insurance mechanisms to citizens is key if political pressure for capital controls is to be averted and if public support for an open, liberal international financial order is to be maintained. The author briefly reviews how today's international financial system evolved from one of mostly closed capital accounts immediately after World War II to today's enormous, largely free-flowing market. Drawing on insights from the literature on public choice and constitutional political economy, the author develops an analytical framework for a welfare cost-benefit analysis of financial openness to international capital flows. The main welfare benefits of financial openness derive from greater economic efficiency and increased opportunities for risk diversification. The welfare costs relate to the cost of insurance used as a mechanism for coping with the risks of financial volatility. These insurance costs are the economic losses associated with redistribution, including moral hazard, rent-seeking, and rent-avoidance. A cross-sectional analysis of a large sample of developed and developing countries shows the positive correlation between democracy (as defined by political and civil liberty) and financial openness. More rigorous econometric investigation using logit analysis and controlling for level of income also shows that redistributive social policies are key in determining the likelihood that countries can successfully combine an openness to international capital mobility with democratic forms of government.
Creep rupture of polymer-matrix composites

The time-dependent creep-rupture process in graphite-epoxy laminates is examined as a function of temperature and stress level. Moisture effects are not considered. An accelerated characterization method of composite-laminate viscoelastic modulus and strength properties is reviewed. It is shown that lamina-modulus master curves can be obtained using a minimum of normally performed quality-control-type testing. Lamina-strength master curves, obtained by assuming a constant-strain-failure criterion, are presented along with experimental data, and reasonably good agreement is shown to exist between the two. Various phenomenological delayed failure models are reviewed and two (the modified rate equation and the Larson-Miller parameter method) are compared to creep-rupture data with poor results.
The Effects of Exposure to Better Neighborhoods on Children: New Evidence from the Moving to Opportunity Experiment

The Moving to Opportunity (MTO) experiment offered randomly selected families housing vouchers to move from high-poverty housing projects to lower-poverty neighborhoods. We analyze MTO’s impacts on children’s long-term outcomes using tax data. We find that moving to a lower-poverty neighborhood when young (before age 13) increases college attendance and earnings and reduces single parenthood rates. Moving as an adolescent has slightly negative impacts, perhaps because of disruption effects. The decline in the gains from moving with the age when children move suggests that the duration of exposure to better environments during childhood is an important determinant of children’s long-term outcomes. (JEL I31, I38, J13, R23, R38)
On the complexity of error explanation

When a system fails to satisfy its specification, the model checker produces an error trace (or counter-example) that demonstrates an undesirable behavior, which is then used in debugging the system. Error explanation is the task of discovering errors in the system or the reasons why the system exhibits the error trace. While there has been considerable recent interest in automating this task and developing tools based on different heuristics, there has been very little effort in characterizing the computational complexity of the problem of error explanation.In this paper, we study the complexity of two popular heuristics used in error explanation. The first approach tries to compute the smallest number of system changes that need to be made in order to ensure that the given counter-example is no longer exhibited, with the intuition being that these changes are the errors that need fixing. The second approach relies on the observation that differences between correct and faulty runs of a system shed considerable light on the sources of errors. In this approach, one tries to compute the correct trace of the system that is closest to the counter-example. We consider three commonly used abstractions to model programs and systems, namely, finite state Mealy machines, extended finite state machines and pushdown automata. We show that the first approach of trying to find the fewest program changes is NP-complete no matter which of the three formal models is used to represent the system. Moreover we show that no polynomial factor approximation algorithm for computing the smallest set of changes is possible, unless P = NP. For the second approach, we present a polynomial time algorithm that finds the closest correct trace, when the program is represented by a Mealy machine or a pushdown automata. When the program is represented by an extended finite state machine, the problem is once again NP-complete, and no polynomial factor approximation algorithm is likely.
Sensitivity of cropping patterns in Africa to transient climate change

The detailed analysis of current cropping areas in Africa presented here reveals significant climate sensitivities of cropland density and distribution across a variety of agro-ecosystems. Based on empirical climate-cropland relationships, cropland density responds positively to increases in precipitation in semi-arid and arid zones of the sub-tropics and warmer temperatures in higher elevations. As a result, marginal increases in seasonal precipitation lead to denser cropping areas in arid and semi-arid regions. Warmer temperatures, on the other hand, tend to decrease the probability of cropping in most parts of Africa (the opposite is true for increases in rainfall and decreases in temperatures relative to current conditions). Despite discrepancies and uncertainties in climate model output, the analysis suggests that cropland area in Africa is likely to decrease significantly in response to transient changes in climate. The continent is expected to have lost on average 4.1 percent of its cropland by 2039, and 18.4 percent is likely to have disappeared by the end of the century. In some regions of Africa the losses in cropland area are likely to occur at a much faster rate, with northern and eastern Africa losing up to 15 percent of their current cropland area within the next 30 years or so. Gains in cropland area in western and southern Africa due to projected increases in precipitation during the earlier portions of the century will be offset by losses later on. In conjunction with existing challenges in the agricultural sector in Africa, these findings demand sound policies to manage existing agricultural lands and the productivity of cropping systems.
Pure Entertainment or Social Harmony? Understanding Private Returns to Social Spending on Household Ceremonies in China

Recent social spending inflation in China has led to its growth rate far exceeding that of income and other consumption. In this paper, we estimate private returns to social spending, such as higher social status and larger social network that serve as certain functions. In almost all specifications we find that gift spending has significant private returns, but the returns are biased towards richer households. Upon comparing different measures of centrality, we also find that social connections are more accurately characterized when weighted by their intensities (values), capturing their role in mobilizing scarce resource in the network. Furthermore, social status and network may change long-term income trajectory and the resulted consumption. However, our findings do not suggest that they are vehicles through which they could facilitate smoother consumption against shocks. The result does not depend on how heterogeneous the shocks are.
Boundaries of Predictability: Noisy Predictive Regressions

Even if returns are truly forecasted by variables such as the dividend yield, the noise in such a predictive regression may overwhelm the signal of the conditioning variable and render estimation, inference and forecasting unreliable. Unfortunately, traditional asymptotic approximations are not suitable to investigate the small sample properties of forecasting regressions with excessive noise. To systematically analyze predictive regressions, it is useful to quantify a forecasting variable’s signal relative to the noisiness of returns in a given sample. We define an index of signal strength, or information accumulation, by renormalizing the signal-noise ratio. The novelty of our parameterization is that this index explicitly influences rates of convergence and can lead to inconsistent estimation and testing, unreliable R2s, and no out-of-sample forecasting power. Indeed, we prove that if the signal-noise ratio is close to zero, as is the case for many of the explanatory variables previously suggested in the finance literature, model based forecasts will do no better than the corresponding simple unconditional mean return. Our analytic framework is general enough to capture most of the previous findings surrounding predictive regressions using dividend yields and other persistent forecasting variables.
Conceptual Modeling for Multiagent Systems: Applying Interaction-Oriented Programming

Multiagent systems (MAS) are an important paradigm for building complex systems, especially cooperative information systems. Despite much interest in MAS construction, there has not been sufficient progress on the corresponding conceptual modeling representations and techniques. We believe that further extensions to conceptual modeling to include aspects of actions and organizations will be essential for MAS development. These goals are broader than conceptual modeling is traditionally understood, but are essential to deal with the interactive and dynamic aspects of modern applications. We describe an approach termed interaction-oriented programming, which incorporates functionality geared toward coordination, commitment management, and collaboration. This functionality is naturally thought of as providing a conceptual metamodel for describing MAS. We suggest some preliminary methodologies pertaining to the design of coordination and commitment requirements.
Autonomy through SLAM for an Underwater Robot

An autonomous underwater vehicle (AUV) is achieved that integrates state of the art simultaneous localization and mapping (SLAM) into the decision processes. This autonomy is used to carry out undersea target reacquisition missions that would otherwise be impossible with a low-cost platform. The AUV requires only simple sensors and operates without navigation equipment such as Doppler Velocity Log, inertial navigation or acoustic beacons. Demonstrations of the capability show that the vehicle can carry out the task in an ocean environment. The system includes a forward looking sonar and a set of simple vehicle sensors. The functionality includes feature tracking using a graphical square root smoothing SLAM algorithm, global localization using multiple EKF estimators, and knowledge adaptive mission execution. The global localization incorporates a unique robust matching criteria which utilizes both positive and negative information. Separate match hypotheses are maintained by each EKF estimator allowing all matching decisions to be reversible.
Demonstration of an all-optical data format transparent WDM-to-TDM network node with extinction ratio enhancement for reconfigurable WDM networks

Summary form only given. We demonstrate an error-free and nearly penalty-free all-optical WDM-to-TDM node that incorporates the useful functions of: (1) data format transparency; (2) extinction ratio enhancement; (3) time multiplexing; and (4) wavelength shifting, to convert two WDM channels into one high-speed TDM signal. We demonstrate this node by converting two 1-Gbit/s NRZ WDM channels at 1552 and 1548 nm into one 20-Gbit/s TDM signal at 1558-nm, while incurring only a 0.2-dB power penalty. This node may be a key building block for fully functional, dynamically reconfigurable WDM networks, which require transparency and cascadability.
Isospectrality and 3-manifold groups

The Chern-Simons and r-invariants are closely related invariants of a Riemannian 3-manifold. A difference in their behavior under taking a finite covering space is exploited to give an obstruction to a group being the fundamental group of a closed 3-dimensional manifold.
The Effects of Prior Export Performance on Firms' Commitment to Exporting and Marketing Strategy Adaptation to the Foreign Market: Evidence from Small and Medium-sized Exporters

To the best of our knowledge, the international business literature has been examining performance exclusively as a dependent variable. In this paper we argue that performance should also be investigated as an independent variable. Using survey data of over 400 managers responsible for the main export ventures of Portuguese SMEs (Small and Medium Enterprises), it is shown that past performance plays a crucial role in building SMEs' commitment to exporting and to the determination of their current marketing strategy. The findings also show that marketing strategy adaptation to the foreign market is particularly noted in firms exporting to the most developed markets, rather than in firms exporting to the most competitive environments. Future international business research is encouraged to develop a more in-depth understanding of why and how preceding performance affects a firm's commitment to exporting. Similarly, future research should focus on understanding both the direct and indirect relationships between performance and marketing strategy. Such a focus has the potential to provide rich theoretical contributions and generate relevant managerial and public policy implications.
Wait-and-see: Investment options under policy uncertainty

Abstract This paper develops a model of investment decisions in which uncertainty about a one-time change in tax policy induces the firm to temporarily stop investing—to adopt a wait-and-see policy. After the uncertainty is resolved, the firm exploits the tabled projects, generating a temporary investment boom.
Linearly tapered slot antenna with dielectric superstrate

The effect of dielectric superstrate on a linearly tapered slot antenna (LTSA) was investigated experimentally. It was observed that the dielectric superstrate improves the directivity but generally at the expense of higher sidelobe level. It improves the patterns and directivity of the antenna by increasing the electrical length and effective aperture of the antenna. The dielectric superstrate could be used to reduce the physical length and to improve the radiation characteristics of the LTSA. >
Sampling and Bayes' Inference in Scientific Modelling and Robustness

Abstract : Scientific learning is an iterative process employing Criticism and Estimation. Correspondingly the formulated model factors into two complimentary parts - a predictive part allowing model criticism, and a Bayes posterior part allowing estimation. Implications for significance tests, the theory of precise measurement, and for ridge estimates are considered. Predictive checking functions for transformation, serial correlation, bad values, and their relation with Bayesian options are considered. Robustness is seen from a Bayesian viewpoint and examples are given. For the bad value problem a comparison with M estimators is made. (Author)
The Business Case for Complying with Bribery Laws

International businesspeople report that bribery presents one of the most frequent and perplexing issues that they encounter. Their confusion regarding corruption might seem disingenuous. The past fifteen years have witnessed an explosion of scholarly research on corruption. The rules on bribery should pose little mystery for an international businessperson faced with a decision regarding a bribe. And yet, in what David Hess and Thomas Dunfee describe as “the paradox of corruption,” businesses continue to pay bribes. A closer examination of corruption
Materialized view tuning mechanism and usability enhancement

The materialized view technology has been widely adopted in the data warehouse systems to improve query performance. Two key underlying techniques are materialized view incremental refresh and query rewrite. However, due to the potential complexity of the materialized view defining query and dependency on the materialized view change log, not all materialized views are incrementally refreshable or generally query rewritable. Many restrictions need to be applied and addressed which make the materialized view not easy to use. This paper presents Oracle's tuning mechanism/tool to facilitate the materialized view creation by automatically fixing and/or decomposing the defining query and addressing the change log requirements. The resulting materialized view implemented by a set of recommendation statements achieves the goals of incremental maintenance and broad query rewrite.
Information transparency, fairness and labor market efficiency

Abstract We study the role of information transparency on fairness, welfare and efficiency in long-term employment relationships. When information on the firms’ productivity and surplus is revealed, wage offers represent larger shares of potential gains for workers who, in return, respond with higher performance. Workers respond not only to wages, but also to firms’ intentions concerning fairness. We find that, in long-term relationships, transparency is a strong mechanism to promote performance and welfare. It naturally improves relationships between firms and workers, increases workers’ welfare, profits from low productivity jobs and boosts the labor market efficiency.
Randomized Acceleration of Fundamental Matrix Computations

We accentuate the power of several known effective methods by combining them together and adding some novel techniques. As a result, we substantially improve the known record randomized bit-operation complexity estimates for various fundamental computations with integer matrices. This includes the computation of the determinant, minimum and characteristic polynomials, Smith and Frobenius invariant factors, and the eigenvalues. Most of the algorithms can be further accelerated where the input matrix can be multiplied by a vector fast, they can be effectively parallelized and extended to matrix polynomials.
Cryptographic Complexity Classes and Computational Intractability Assumptions

Which computational intractability assumptions are inherent to cryptography? We present a broad framework to pose and investigate this question. We first aim to understand the “cryptographic complexity” of various tasks, independent of any computational assumptions. In our framework the cryptographic tasks are modeled as multi-party computation functionalities. We consider a universally composable secure protocol for one task given access to another task as the most natural complexity reduction between the two tasks. Some of these cryptographic complexity reductions are unconditional, others are unconditionally impossible, but the vast majority appear to depend on computational assumptions; it is this relationship with computational assumptions that we study. In our detailed investigation of large classes of 2-party functionalities, we find that every reduction we are able to classify turns out to be unconditionally true or false, or else equivalent to the existence of one-way functions (OWF) or of semi-honest (equivalently, standalone-secure) oblivious transfer protocols (sh-OT). This leads us to conjecture that there are only a small finite number of distinct computational assumptions that are inherent among the infinite number of different cryptographic reductions in our framework. If indeed only a few computational intractability assumptions manifest in this framework, we propose that they are of an extraordinarily fundamental nature, since the framework contains a large variety of cryptographic tasks, and was formulated without regard to any of the prevalent computational intractability assumptions.
Allocating the costs of parental free exercise: striking a new balance between sincere religious belief and a child's right to medical treatment.

In Prince v. Massachusetts, 321 U.S. 158 (1944), the United States Supreme Court stated, “The right to practice religion freely does not include liberty to expose the community or the child to communicable disease or the latter to ill health or death ....” These presumably unambiguous words are in sharp contrast to the reality that parents may still legally cloak themselves in the first amendment and its free exercise clause to deny their children medical treatment, even when those children die. Some churches take the position that their members have no legal duty to provide their children with medical treatment because there are religious exemptions under state child neglect laws. Such exemptions prevent states from prosecuting a parent for the misdemeanor of child neglect for the sole reason that a parent relies on treatment by spiritual means instead of seeking medical attention for a child. These exemptions can be found in virtually every state in the country. The United States Supreme Court has never squarely addressed the validity of these exemptions. This article argues that not only are such exemptions not constitutionally mandated, in fact, they are constitutionally infirm. Courts should strike down such exemptions on public policy grounds and states should repeal them.
Regioselective O2′,O3′‐Deacetylations of Peracetylated Ribonucleosides by Using Tetra‐n‐butylammonium Fluoride

A robust, mild, and highly regioselective deacetylation of 1,2-diol diacetates in the presence of other acetate functions was achieved by using tetra-n-butylammonium fluoride. This method provided a single-step route to access O5′-acetyl ribonucleosides, a key intermediate in the synthesis of biomedically important nucleosides and nucleotides. Moreover, it offered the general applicability of a non-enzymatic method for the selective deacetylation of peracetylated 2′-deoxyribonucleosides. Its synthetic utility was further demonstrated by the synthesis of molecules of biomedical interest by using this particular deacetylation reaction.
The dynamics of poverty and the effectiveness of Poland's safety net (1993-96)

The author analyzes how the incidence of household endowments and the allocation of social benefits affect families' transitions into and out of poverty. Using panel data for 1993-96 from Poland's Household Budget Survey, and a framework based on sample survival analysis techniques, the author evaluates how various policies will affect households with specific characteristics that make them likely to become poor or to move out of poverty under different scenarios (including whether or not they receive a given amount of a particular type of social transfer). He also discusses how non-income sources of welfare, such as savings, credits, and loans, affect the likelihood that families will become or stop being poor. He concludes that family allowances and unemployment benefits, the two major social programs analyzed, have significant but different effects on different groups of households (characterized in terms of age, gender, marital status, and educational attainment of the head of household; the size, type, location, and sector of employment of the family or household; and the year in which the household fell into poverty). If the share of the family allowances in total household income were reduced by 1 percent, for example, the average length of poverty would be increased by roughly 2 percent. But a 1 percent change in unemployment benefits would yield a 3 percent change in the average duration of poverty. Differences in hazard rates for various subgroups would be even greater. Households in villages were much more likely to fall into poverty than households in cities and large towns, but the poor in towns and cities had more difficulty exiting poverty. There was generally less poverty mobility among households headed by public sector employees than among those headed by employees in the private sector. Families with three or more children and one-parent families (and grandparents with children) faced the greatest risk of being poor; single-person households and childless married couples were the least endangered . Small nuclear families with one or two children and families without children fell between these two extremes.
Only n -qubit Greenberger-Horne-Zeilinger states contain n -partite information

The generalized $n$-qubit Greenberger-Horne-Zeilinger (GHZ) states and their local unitary equivalents are the only pure states of $n$ qubits that are not uniquely determined (among arbitrary states, pure or mixed) by their reduced density matrices of $n\ensuremath{-}1$ qubits. Thus, the generalized GHZ states are the only ones containing information at the $n$-party level.