cssi/SciSciGPT-SciSciNet huggingface dataset:
The Social Utility of Feature Creep

Abstract Previous research has shown that consumers frequently choose products with too many features that they later find difficult to use. In this research, the authors show that this seemingly suboptimal behavior may actually confer benefits when factoring in the social context of consumption. The results demonstrate that choosing products with more capabilities (i.e., feature-rich products) provides social utility beyond inferences of wealth, signaling consumers' technological skills and openness to new experiences and that consumers' beliefs about the social utility of feature-rich products are predictive of their choices of such products. Furthermore, the authors examine when impression management concerns increase consumers' likelihood of choosing feature-rich products. They find that public choices in which participants display their preferences to others encourage feature-seeking behavior but that the anticipation of having to use a product in front of others provides an incentive to avoid additi...
Hypersingular integrals at a corner

Abstract For a smooth boundary, hypersingular integrals can be defined as a limit from the interior, the approach direction being taken, for convenience, normal to the surface. At a boundary corner, the limit process, with a necessarily non-normal approach direction, provides a valid definition of the hypersingular equation, as long as the same direction is employed for all integrations. The terms which are potentially singular in the limit are shown to cancel, provided the function approximations at the corner are consistent. The analytical formulas for the singular integrals are more complicated than for a smooth surface, but are easily obtained using symbolic computation. These techniques have been employed to accurately solve the ‘L-shaped domain’ potential considered by Jaswon and Symm (Integral Equation Methods in Potential Theory and Elastostatics, Academic Press, New York, USA, 1977).
Axial ligand orientation in crystalline modifications of bis(2,6-lutidine-N-oxide)(tetraphenylporphinato)manganese(III) perchlorate

Abstract An X-ray crystallographic structure determination of a second crystalline modification of the reactive metalloporphyrin bis(2,6-1utidine- N -oxide)(tetraphenylporphinato)manganese( III ) perchlorate was performed. The complex crystallized as dark green rods out of a toluene/heptane solvent system in the monoclinic space group P 2 1 / c (#14), with a = 20.385(13), b =12.207(4), c =24.031(25) ;A, β= 113.07(7)°; Z =4. The structure was refined to final residuals of R =0.0692 and R w =0.0699. The orientations of the two 2,6-1utidine- N -oxide axial ligands with respect to one another as well as to the porphyrin ring are nearly identical in this structure as in the structure for the purple-red prism crystalline modification of this complex ( C 2/ c ) reported previously. An explanation for the orientation of the axial ligands in these two complexes based on a combination of crystal packing forces and intramolecular electronic factors is presented.
A framework for structured quantum search

Abstract A quantum algorithm for general combinatorial search that uses the underlying structure of the search space to increase the probability of finding a solution is presented. This algorithm shows how coherent quantum systems can be matched to the underlying structure of abstract search spaces. The algorithm is evaluated empirically with a variety of search problems, and shown to be particularly effective for searches with many constraints. Furthermore, the algorithm provides a simple framework for utilizing search heuristics. It also exhibits the same phase transition in search difficulty as found for sophisticated classical search methods, indicating that it is effectively using the problem structure.
Reconfigurable Redundancy Management for Aircraft Flight Control

A highly fault tolerant digital computer system has been configured based on extensive experience with flight proven, redundant digital flight control systems. The feasibility of minimizing hardware complexity is shown while maintaining high levels of fault tolerance. The emerging hardware design combines reconfiguration concepts with conventional hardware redundancy techniques and special operational software to provide dual fail operate performance with a basic triplex system. The design provides high reliability and flight safety, enhances maintainability, and reduces life cycle cost while offering improved performance for future aircraft.
Differentiability at the edge of the percolation cone and related results in first-passage percolation

We study first-passage percolation in two dimensions, using measures μ on passage times with b: = inf supp(μ) > 0 and \({\mu(\{b\})=p\geq \vec p_c}\) , the threshold for oriented percolation. We first show that for each such μ, the boundary of the limit shape for μ is differentiable at the endpoints of flat edges in the so-called percolation cone. We then conclude that the limit shape must be non-polygonal for all of these measures. Furthermore, the associated Richardson-type growth model admits infinite coexistence and if μ is not purely atomic the graph of infection has infinitely many ends. We go on to show that lower bounds for fluctuations of the passage time given by Newman–Piza extend to these measures. We establish a lower bound for the variance of the passage time to distance n of order log n in any direction outside the percolation cone under a condition of finite exponential moments for μ. This result confirms a prediction of Newman and Piza (Ann Probab 23:977–1005, 1995) and Zhang (Ann Probab 36:331–362, 2008). Under the assumption of finite radius of curvature for the limit shape in these directions, we obtain a power-law lower bound for the variance and an inequality between the exponents χ and ξ.
Raising Roofs, Crashing Cycles, and Playing Pool: Applications of a Data Structure for Finding Pairwise Interactions

The straight skeleton of a polygon is a variant of the medial axis introduced by Aichholzer et al., defined by a shrinking process in which each edge of the polygon moves inward at a fixed rate. We construct the straight skeleton of an n -gon with r reflex vertices in time O(n 1+e + n 8/11+e r 9/11+e ) , for any fixed e >0 , improving the previous best upper bound of O(nr log n) . Our algorithm simulates the sequence of collisions between edges and vertices during the shrinking process, using a technique of Eppstein for maintaining extrema of binary functions to reduce the problem of finding successive interactions to two dynamic range query problems: (1) maintain a changing set of triangles in R 3 and answer queries asking which triangle is first hit by a query ray, and (2) maintain a changing set of rays in R 3 and answer queries asking for the lowest intersection of any ray with a query triangle. We also exploit a novel characterization of the straight skeleton as a lower envelope of triangles in R 3 . The same time bounds apply to constructing non-self-intersecting offset curves with mitered or beveled corners, and similar methods extend to other problems of simulating collisions and other pairwise interactions among sets of moving objects.
Excited heavy mesons and kaon loops in chiral perturbation theory

Abstract We consider the effects of excited states on the SU (3) breaking chiral loop corrections to heavy meson properties. In particular, we compare the size of kaon loops in which an excited heavy meson appears to the size of previously calculated loops with heavy mesons in the ground state. We find that the new effects may indeed be of the same magnitude as the old ones, but that there is a strong dependence on the unknown masses and coupling constants of the new states. As a result, we argue that the ground state loops alone may not be a trustworthy guide to SU (3) corrections, and that the appropriate cutoff for a heavy-light chiral lagrangian which omits excited heavy mesons may be considerably smaller than the naive expectation of Λ x ≈ 1 GeV .
Structured Vibration Modes of General Compound Planetary Gear Systems

This paper extends previous analytical models of simple, single-stage planetary gears to compound, multi-stage planetary gears. This model is then used to investigate the structured vibration mode and natural frequency properties of compound planetary gears of general description, including those with equally spaced planets and diametrically opposed planet pairs. The well-defined cyclic structure of simple, single-stage planetary gears is shown to be preserved in compound, multi-stage planetary gears. The vibration modes are classified into rotational, translational, and planet modes and the unique properties of each type are examined and proved for general compound planetary gears. All vibration modes fall into one of these three categories. For most cases, both the properties of the modes and the modes themselves are shown to be insensitive to relative planet positions between stages of a multi-stage system. DOI: 10.1115/1.2345680
Developing Adiabatic Two Phase Flow in Headers - Distribution Issue in Parallel Flow Microchannel Heat Exchangers

Heat exchangers with microchannels (hydraulic diameter less than 1 mm) are attracting significant attention lately. Performance of these heat exchangers mostly evaporators is greatly affected by imperfect distribution of a two-phase fluid to each channel. This paper presents an overview of the issue, showing basic options to evenly distribute single and two-phase fluid and the methods to determine maldistribution. Special attention is given to describing two-phase regimes in an adiabatic horizontal header with R134a as a fluid, describing a two-phase map with area of good distribution.
Decomposition technique and optimal trajectories for the aeroassisted flight experiment

The aeroassisted flight experiment (AFE) refers to a spacecraft to be launched and then recovered by the space shuttle in 1994. It simulates a transfer from a geosynchronous Earth orbit (GEO) to a low Earth orbit (LEO). Specifically, the AFE spacecraft is released from the space shuttle and is accelerated by means of a solid rocket motor toward Earth, so as to achieve atmospheric entry conditions close to those of a spacecraft returning from GEO. Following the atmospheric pass, the AFE spacecraft ascends to the specified LEO via an intermediate parking Earth orbit (PEO). The final maneuver includes the rendezvous with and the capture by the space shuttle. The entry and exit orbital planes of the AFE spacecraft are identical with the orbital plane of the space shuttle. In this paper, with reference to the AFE spacecraft, an actual GEO-to-LEO transfer is considered and optimal trajectories are determined by minimizing the total characteristic velocity. The optimization is performed with respect to the time history of the controls (angle of attack and angle of bank), the entry path inclination and the flight time being free. Two transfer maneuvers are considered: (DA) direct ascent to LEO; (IA) indirect ascent to LEO via PEO. While the motion of the AFE spacecraft in a 3D-space is described by a system of six ODEs, substantial simplifications are possible if one exploits these facts: (i) the instantaneous orbital plane is nearly identical with the initial orbital plane; (ii) the bank angle is small; and (iii) the Earth's angular velocity is relatively small. Under these assumptions, the complete system can be decoupled into two subsystems, one describing the longitudinal motion and one describing the lateral motion. The angle of attack history, the entry path inclination, and the flight time are determined via the longitudinal motion subsystem; in this subsystem, the total characteristic velocity is minimized subject to the specified LEO requirement. The angle of bank history is determined via the lateral motion subsystem; in this subsystem, the difference between the instantaneous bank angle and a constant bank angle is minimized in the least square sense subject to the specified orbital inclination requirement. It is shown that both the angle of attack and the angle of bank are constant. This result has considerable importance in the design of nominal trajectories to be used in the guidance of AFE and AOT vehicles.
A new set of calibration standards for estimating the fat and mineral content of vertebrae via dual energy QCT

Abstract A new set of calibration standards has been developed for implementing a dual-energy (DE) quantitative CT technique for estimating the fat and bone content of vertebrae. The QCT technique is based upon a three-component model of bone and utilizes calibration materials that mimic those components in their X-ray attenuation properties. The three components we chose to simulate are bone (mineral plus collagen), fat and a fat-free red marrow. This choice was predicated upon our desire to employ materials that would facilitate later experimental verification of the method. The calibration standards and a set of test samples were manufactured of tissue-simulating epoxy resins. They were employed in studies of the accuracy (consistency) and precision of the technique and in a study of 21 normal postmenopausal women. Estimates of the bone and fat content of the test samples were consistent with the manufacturer's specifications to within 13 mg/ml and 7 vol%, respectively. Long-term reproducibility (coefficient of variation) for both quantities was about 3%. The average bone content of the T12-L3 vertebrae of the human subjects was 262 ± 32 mg/ml (152 ± 18 mg/ml calcium hydroxyapatite or mineral) and the average fat content was 63 ± 8%. Conventional single energy (SE) QCT measurements of these vertebrae were about 23% less than the DE mineral measurements, which is consistent with the differences between SEQCT and ash content that others have determined via chemical analysis. The DE fat content is, in absolute terms, about 15% greater than values reported in the literature and may be due to an error in the assumed composition of red marrow. The true accuracy of the bone and fat estimates is to be determined in a planned human vertebral specimen study.
Towards the chemoenzymatic synthesis of lipid A

Abstract New procedures have been developed for the synthesis of the two important components of lipid A; one is the lipase-catalyzed resolution of 3-hydroxyteradecanoic acid in tetrahydrofuran using vinyl acetate and the other is the synthesis of the disaccharide moiety using glycosylphosphite as the glycosylating reagenL
NEW CONSTRAINTS ON ADDITIONAL SATELLITES OF THE PLUTO SYSTEM

Observations of Pluto and its solar-tidal stability zone were made using the Advanced Camera for Surveys (ACS) Wide Field Channel (WFC) on the Hubble Space Telescope on UT 2005 May 15 and May 18. Two small satellites of Pluto, provisionally designated S/2005 P1 and S/2005 P2, were discovered, as discussed by Weaver et al. and Stern et al. Confirming observations of the newly discovered moons were obtained using the ACS in the High Resolution Channel (HRC) mode on 2006 February 15 (Mutchler et al.). Both sets of observations provide strong constraints on the existence of any additional satellites in the Pluto system. Based on the 2005 May observations using the ACS WFC, we place a 90% confidence lower limit of mV = 26.8 (mV = 27.4 for a 50% confidence lower limit) on the magnitude of undiscovered satellites greater than 5'' (1.1 × 105 km) from Pluto. Using the 2005 February 15 ACS HRC observations we place 90% confidence lower limits on the apparent magnitude of any additional satellites of mV = 26.4 between 3'' and 5'' (6.9 × 104-1.1 × 105 km) from Pluto, mV = 25.7 between 1'' and 3'' (2.3 × 104-6.9 × 104 km) from Pluto, and mV = 24 between 03 and 1'' (6.9 × 103-2.3 × 104 km) from Pluto. The 90% confidence magnitude limits translate into upper limits on the diameters of undiscovered satellites of 29 km outside of 5'' from Pluto, 36 km between 3'' and 5'' from Pluto, 49 km between 1'' and 3'' from Pluto, and 115 km between 03 and 1'' for a comet-like albedo of pV = 0.04. If potential satellites are assumed to have a Charon-like albedo of pV = 0.38, the diameter limits are 9, 12, 16, and 37 km, respectively.
Measuring the success of retention management models built on churn probability, retention probability, and expected yearly revenues

We claim that often marketers have not all the information to develop various marketing campaign models. For example, marketers may have sufficient information to build a model for predicting possible churners, while they may have no clues of which customers are most likely to accept a retention campaign. In this paper, we first show that the information useful for a successful churner prediction model alone is not sufficient to develop a successful retention marketing program. In such a case, we claim that only theory-based simulation approach is feasible. In particular, it is claimed that optimal retention management models should consider not only churn probability but also retention probability and expected revenues from target customers. To validate our claim, we develop and compare five retention management models based on churn probability, retention probability, expected revenues, and combination of these models along with different evaluation metrics. Our experimental results show that the retention management model with the highest accuracy in predicting possible churners is not necessarily optimal because it does not consider the probability of accepting retention promotions. In contrast, the retention management model based on both churn and retention probability is the best in terms of predicting customers who are most likely to positively respond to retention promotions. Ultimately, the model based on expected yearly revenue of customers accrues the highest revenues across most target points, making it the best model out of five churn management models.
Limit groups for relatively hyperbolic groups. I. The basic tools

We begin the investigation of -limit groups, where is a torsion-free group which is hyperbolic relative to a collection of free abelian subgroups. Using the results of (16), we adapt the re- sults from (21) and (22) to this context. Specifically, given a finitely generated group G, and a sequence of pairwise non-conjugate ho- momorphisms {hn : G ! }, we extract an R-tree with a nontrivial isometric G-action. This, along with the analogue of Sela's shortening argument allows us to prove the main result of this paper, that is Hopfian. In his remarkable series of papers (38, 39, 41), Z. Sela has classified those finitely generated groups with the same elementary theory as the free group of rank 2 (see also (40) for a summary). This class includes all nonabelian free groups, most surface groups, and certain other hyperbolic groups. In particular, Sela answers in the positive some long-standing questions of Tarski (Kharlampovich and Miasnikov have another approach to these problems; see (29)). In (38), Sela begins with a study of limit groups. Sela's definition of a limit group is geometric, though it turns out that a group is a limit group if and only if it is a finitely generated fully-residually free group. Sela then produces Makanin-Razborov diagrams, which give a parametrization of Hom(G,F), where G is an arbitrary finitely gener- ated group and F is a nonabelian free group (such a parametrisation is also given in (28)). Over the course of his six papers, two of the main tools Sela uses are the theory of isometric actions on R-trees and the shortening argument. Sela's work naturally raises the question of which other classes of groups can be understood using Sela's approach. Many of Sela's meth- ods (and, more strikingly, some of the answers) come from geometric group theory. Thus it seems natural to consider, when looking for classes of groups to apply these methods to, groups of interest in geo- metric group theory. In (42), Sela considers an arbitrary torsion-free
Cardiac sympathetic tone in anaesthetized diabetics.

To assess cardiac sympathetic nervous function in diabetics, the heart rates attained following a pharmacological dose of intravenous atropine, 23 μg · kg−1, were studied under N2O, isoflurane anaesthesia in diabetics (n = 21) and nondiabetics (n = 30). Atropine-induced heart rate in diabetics was significantly lower than that in nondiabetics (95 ± 14 (SD) bpm vs 109 ±12 bpm, P < 0.001) and were closely related to preoperative orthostatic diastolic blood pressure change (r = 0.60, P < 0.01). There was some correlation between the atropine-induced heart rate and preoperative RR-variation in diabetics (r = 0.50, P < 0.05). The findings suggest that cardiac sympathetic function may also be impaired in diabetics with orthostatic hypotension.
The growth of 2-D pits in thin film aluminum

Abstract Pitting in chloride solutions of 1000–2000 A thick films of Al evaporated onto quartz substrates was studied. The anodic dissolution and hydrogen evolution current densities in the pit were both constant with time. The anodic current density and the pit morphology were, however, dependent on the pit growth potential. At low potentials, the pit current density increased linearly with potential, the pit surface was extremely rough, and pit growth was determined to be under ohmic control. At higher potentials, the pit current density was independent of potential and the pits became round and smooth, indicating that mass transport was rate limiting.
Speckle Decorrelation and Dynamic Range in Speckle Noise-limited Imaging

The useful dynamic range of an image in the diffraction-limited regime is usually limited by speckles caused by residual phase errors in the optical system forming the image. The technique of speckle decorrelation involves introducing many independent realizations of additional phase error into a wave front during one speckle lifetime, changing the instantaneous speckle pattern. A commonly held assumption is that this results in the speckles being "moved around" at the rate at which the additional phase screens are applied. The intention of this exercise is to smooth the speckles out into a more uniform background distribution during their persistence time, thereby enabling companion detection around bright stars to be photon noise limited rather than speckle limited. We demonstrate analytically why this does not occur and confirm this result with numerical simulations. We show that the original speckles must persist and that the technique of speckle decorrelation merely adds more noise to the original speckle noise, thereby degrading the dynamic range of the image.
Application of Spectral Remote‐Sensing Method for Recovering Temperature Distribution in Glass

A method for recovering the temperature distribution in glass from remotely sensed spectral emission data was studied. The temperature distribution, which was related analytically to the spectral emerging intensity, was determined by an optimization technique that minimizes the difference between measured and calculated emissions. The method was evaluated by measuring spectral emission from heated glass using both a spectrometer and a spectroradiometer. Data were taken from 600 to 900 K for window glass samples with different back-surface boundary conditions. The recovered temperature profiles obtained using data from both measuring instruments were compared with each other and with temperature profiles predicted from a combined conduction-radiation heat-transfer analysis. When only 2 unknown coefficients were used to represent the temperature distribution, the recovered and predicted profiles agreed within 1%.
The blindness of John Milton.

John Milton (1608–1674) often has been regarded as the greatest poet of his time, yet he did not compose his most famous work,Paradise Lost, until after he had become blind in both eyes. On the basis of clues in Milton's writings, several possible diagnoses have been advanced to explain his loss of vision. The evidence for and against each theory is presented.
Direct and indirect limits on the electro-magnetic form factors of WIMPs

Abstract We use the results of direct and indirect searches for weakly interacting massive particles (WIMPs) to obtain bounds on various electro-magnetic form factors of WIMPs. The limits on the recoil signal in underground dark matter detection experiments, with standard assumptions about the density and r.m.s. velocity of WIMPs in the halo, can be translated into the following model-independent bounds on the magnetic dipole, electric dipole, quadrupole and anapole moments and the polarizability of WIMPs: μ/μn d −21 e cm , Q −7 fm 2 , a/μ n −2 fm , and χ −8 fm 3 for a WIMP mass of 100 GeV. The limits on fluxes of highly energetic neutrinos produced in the annihilation of WIMPs in the center of the earth and the sun lead to somewhat stronger, but more model dependent bounds.
Elimination of numerical dispersion in finite-difference modeling and migration by flux-corrected transport

Finite-difference acoustic-wave modeling and reverse-time depth migration based on the full wave equation are general approaches that can take into account arbitrary variations in velocity and density and can handle turning waves as well. However, conventional finite-difference methods for solving the acoustic- or elastic-wave equation suffer from numerical dispersion when too few samples per wavelength are used. The flux-corrected transport (FCT) algorithm, adapted from hydrodynamics, reduces the numerical dispersion in finite-difference wavefield continuation. The flux-correction procedure endeavors to incorporate diffusion into the wavefield continuation process only where needed to suppress the numerical dispersion. Incorporating the flux-correction procedure in conventional finite-difference modeling or reverse-time migration can provide finite-difference solutions with no numerical dispersion even for impulsive sources. The FCT correction, which can be applied to finite-difference approximations of any order in space and time, is an efficient alternative to use for finite-difference approximations of increasing order. Through demonstrations of modeling and migration on both synthetic and field data, we show the benefits of the FCT algorithm, as well as its inability to fully recover resolution lost when the spatial sampling becomes too coarse.
A result on the computational complexity of heuristic estimates for the A* algorithm

Abstract The performance of a new heuristic search algorithm is analyzed. The algorithm uses a formal representation (semantic representation) that contains enough information to compute the heuristic evaluation function h(n), as defined in the context of A ∗ , without requiring a human expert to provide it. The heuristic is computed by solving less constrained subproblems (auxiliary problems) of the given problem. The new algorithm is shown to be less efficient than the Dijkstra algorithm, according to the complexity measure “number of node expansions.” This proves that it is not efficient to compute heuristics for A ∗ by solving auxiliary problems with backtracking.
Numerical solution of two-dimensional compressible radiating flowfields

A two-dimensional numerical model for flows with coupled radiation from an emitting, absorbing, and scattering fluid is developed. The continuity, momentum, and energy equations are approximated by a finite-difference method, and the radiative transfer equation is discretized by the product-integration method in which the shape function is taken to be piecewise-constant. The numerical grid for the radiation field is matched with the flowfield grid, and the continuity, momentum, and energy equations are coupled with the radiative transfer equation to obtain steady-state solutions. The model is verified by comparison with existing solutions for a laminar Poiseuille flow. Some sample calculations of inviscid supersonic flow of an ideal gas through a twodimensional diffuser are presented to show the effect of radiation on the temperature field in the diffuser.
Mean Motion Resonances in Exoplanet Systems: An Investigation into Nodding Behavior

Motivated by the large number of extrasolar planetary systems that are near mean motion resonances, this paper explores a related type of dynamical behavior known as "nodding." Here, the resonance angle of a planetary system executes libration (oscillatory motion) for several cycles, circulates for one or more cycles, and then enters once again into libration. This type of complicated dynamics can affect our interpretation of observed planetary systems that are in or near mean motion resonance. This work shows that planetary systems in (near) mean motion resonance can exhibit nodding behavior, and outlines the portion of parameter space where it occurs. This problem is addressed using both full numerical integrations of the planetary systems and via model equations obtained through expansions of the disturbing function. In the latter approach, we identify the relevant terms that allow for nodding. The two approaches are in agreement, and show that nodding often occurs when a small body is in an external mean motion resonance with a larger planet. As a result, the nodding phenomenon can be important for interpreting observations of transit timing variations, where the existence of smaller bodies is inferred through their effects on larger, observed transiting planets. For example, in actively nodding planetary systems, both the amplitude and frequency of the transit timing variations depend on the observational time window.
Side-Force Alleviation on Slender, Pointed Forebodies at High Angles of Attack

A new device was proposed for alleviating high angle-of-attack side force on slender, pointed forebodies. A symmetrical pair of separation strips in the form of helical ridges are applied to the forebody to disrupt the primary lee-side vortices and thereby avoid the instability that produces vortex asymmetry. Preliminary wind tunnel tests at Mach 0.3 and Reynolds no. 5,250,000 on a variety of forebody configurations and on a wing-body combination at angles of attack up to 56 degrees, demonstrated the effectiveness of the device.
KINETIC MONTE CARLO SIMULATION OF DISLOCATION DYNAMICS

A kinetic Monte Carlo simulation of dislocation motion is introduced. The dislocations are assumed to be composed of pure edge and screw segments confined to a fixed lattice. The stress and temperature dependence of the dislocation velocity is studied, and finite-size effects are discussed. It is argued that surfaces and boundaries may play a significant role in the velocity of dislocations. The simulated dislocations are shown to display kinetic roughening according to the exponents predicted by the Kardar-Parisi-Zhang equation.
Computing with Voting Trees

A central challenge in social choice theory arises from the fact that there is no fair way to deterministically select a winner in an election among more than two candidates; the only definite collective preferences are between individual pairs of candidates. Combinatorially, one may summarize this information with a graph-theoretic tournament on $n$ vertices (one per candidate), placing an edge from $u$ to $v$ if $u$ would beat $v$ in an election between only those two candidates (no ties are permitted). One well-studied procedure for selecting a winner is to specify a binary tree whose leaves are labeled by the candidates and evaluate it by running pairwise elections between the pairs of leaves, sending the winners to successive rounds of pairwise elections which ultimately terminate with a single winner. This structure is called a voting tree. Much research has investigated which functions on tournaments are computable in this way. Fischer, Procaccia, and Samorodnitsky quantitatively studied the comput...
New mathematical structures in renormalizable quantum field theories

Abstract Computations in renormalizable perturbative quantum field theories reveal mathematical structures which go way beyond the formal structure which is usually taken as underlying quantum field theory. We review these new structures and the role they can play in future developments.
Ridesharing in North America: Past, Present, and Future

Since the late 1990s, numerous ridematching programmes have integrated the Internet, mobile phones, and social networking into their services. Online ridematching systems are employing a range of new strategies to create "critical mass": (1) regional and large employer partnerships, (2) financial incentives, (3) social networking to younger populations, and (4) real-time ridematching services that employ "smartphones" and automated ridematching software. Enhanced casual carpooling approaches, which focus on "meeting places", are also being explored. Today, ridesharing represents approximately 8-11% of the transportation modal share in Canada and the USA, respectively. There are approximately 638 ridematching programmes in North America. Ridesharing's evolution can be categorized into five phases: (1) World War II car-sharing (or carpooling) clubs; (2) major responses to the 1970s energy crises; (3) early organized ridesharing schemes; (4) reliable ridesharing systems; and (5) technology-enabled ridematching. While ridesharing's future growth and direction are uncertain, the next decade is likely to include greater interoperability among services, technology integration, and stronger policy support. In light of growing concerns about climate change, congestion, and oil dependency, more research is needed to better understand ridesharing's impacts on infrastructure, congestion, and energy/emissions.
Evaluation of titanium alkoxides and aryloxides in the Kulinkovich cyclopropanation of carboxylic esters

Abstract Systematic evaluation of several titanium alkoxides and aryloxides was undertaken in the titanium-mediated cyclopropanation reactions of carboxylic esters. Chlorotitanium triisopropoxide and/or methyltitanium triisopropoxide were found to be the reagents of choice for the olefin exchange modification, whereas the original Kulinkovich process proved to be insensitive to the nature of titanium alkoxides and aryloxides.
Probing polarized parton distributions with meson photoproduction

Polarization asymmetries in photoproduction of high transverse momentum mesons are a flavor sensitive way to measure the polarized quark distributions. the authors calculate the expected asymmetries in several models, and find that the asymmetries are significant and also significantly different from model to model. Suitable data may come as a by-product of deep inelastic experiments to measure g{sub 1} or from dedicated experiments.
Jensen, Myers-Majluf, free cash flow and the returns to bidders

Abstract Previous research has shown that returns to bidders are significantly negative for stock acquisitions and insignificant although slightly positive for cash acquisitions. Two theories (Jensen and Myers-Majluf) would predict positive returns to bidders in cash acquisitions which use up excess cash flow and slack. This study investigates bidder returns using these theories and the Lang, Stulz, and Walkling proxy for free cash flow. It finds that cash bidders that have low q and sizable free cash flow and that reinvest a high percentage of this free cash flow have significant positive returns as Jensen's theory predicts. It finds no evidence supporting the Myers-Majluf theory. Cash bidders without Lang, Stulz, and Walkling free cash flow have returns that are negative and essentially indistinguishable from those of stock bidders.
El rol del Estado como creador de empleo

El largo debate sobre el rol del Estado en la generacion de empleo todavia permanece como un tema central en las Americas y en otras regiones. El Barometro de las Americas 2008 encuentra que los niveles de apoyo del ciudadano "promedio", a que el Estado en vez del sector privado sea el principal actor en la creacion de puestos de trabajo, alcanzan 56,4 puntos o mas, en una escala de 0-100, en todos los paises de America Latina o del Caribe incluidos en la encuesta del Barometro de las Americas. Individuos que viven en hogares ricos se oponen significativamente al rol del Estado como principal generador de trabajo, pero, al contrario, mientras mas rico es el pais en terminos de ingreso per capita mayor es el rol que se espera del Estado como generador de empleo. Hay implicaciones importantes en cuanto a la politica economica del Estado.
Regional relationships among earthquake magnitude scales

Various magnitude scales commonly used and the interrelationships among them are reviewed. It is shown that problems exist with all of the magnitude scales being used in the United States. When using regional catalogs, for example, it is often necessary to determine how the reported magnitudes were determined. Often such information is not available, although the potential errors are quite large. Both the MS and the mb scales were designed to be universal scales. However, both MS and mb magnitudes are often determined beyond the applicable range of the equations used to define the two scales. Furthermore, the MS magnitudes are not generally available for moderate to small earthquakes in most earthquake catalogs. The mb magnitudes are more generally available than MS values; however, there is also much greater variation in the way mb is determined. In particular, a significant change in the mb scale occurred in the early 1960’s when the World-Wide Standard Seismograph Network (WWSSN) was established. This change in instrumentation used to determine mb values had a significant effect on estimated magnitudes (post-1960 values are lower) and the saturation level of the mb scale. The older, longer-period instruments recorded larger mb magnitudes than can be recorded with the WWSSN instruments. In addition, great care must be taken when selecting the mb magnitudes of western U.S. earthquakes, because the values are often in considerable error owing to the fact that they were determined at distances less than 25° and were not properly corrected for attenuation in the upper mantle, or asthenosphere. The seismic body wave magnitude mb of an earthquake is strongly affected by regional variations in the Q structure, composition, and physical state within the earth. Therefore because of differences in attenuation of P waves between the western and eastern United States, a problem arises when comparing mb values for the two regions. A regional mb magnitude bias exists which, depending on where the earthquake occurs and where the P waves are recorded, can lead to magnitude errors as large as ⅓ unit. There is also a significant difference between mb and ML values for earthquakes in the western United States. An empirical link between the mb of an eastern U.S. earthquake and the ML of an equivalent western earthquake is given by ML = 0.57 + 0.92(mb)east. This result is important when comparing ground motion between the two regions and for choosing a set of real western U.S. earthquake records to represent eastern earthquakes.
CRYSTAL STRUCTURES OF A TETRAOXY SPIROCYCLIC SELENURANE AND TELLURANE. LONE PAIR EFFECTS

Abstract The crystal structures of the tetraoxy spirocyclic selenurane (C6H12O2)2Se (3) and corresponding tellurane (C6H12O2)2Te (4) have been determined by single-crystal X-ray diffraction analysis. Both compounds crystallize in the monoclinic space group C 2/c with Z = 4 and with the central atom on a crystallographic twofold axis. For 3, a = 10.442 (6) A, b = 10.545 (5) A, c = 13.910 (3) A, and β = 110.27 (3)°. For 4, a = 19.108 (7) A, b = 10.469 (4) A, c = 7.705 (2) A, and β = 97.83°. Data for both compounds were collected on an Enraf-Nonius CAD4 diffractometer out to a maximum 2θMoKα of 50°. Full-matrix least-squares refinement led to R = 0.042 and Rw = 0.055 for 3 and R = 0.034 and Rw = 0.042 for 4. Both exist in a trigonal-bipyramidal structure distorted in compliance with the presence of an equatorially positioned lone electron pair. In the Te compound intermolecular Te[sbnd]O contacts indicate a degree of polymerization making the Te atoms pseudo six-coordinated. No such contact is observed in th...
Geometric WOM codes and coding strategies for multilevel flash memories

This paper investigates the design and application of write-once memory (WOM) codes for flash memory storage. Using ideas from Merkx (1984) we present a construction of WOM codes based on finite Euclidean geometries over $${\mathbb{F}_2}$$ . This construction yields WOM codes with new parameters and provides insight into the criterion that incidence structures should satisfy to give rise to good codes. We also analyze methods of adapting binary WOM codes for use on multilevel flash cells. In particular, we give two strategies based on different rewrite objectives. A brief discussion of the average-write performance of these strategies, as well as concatenation methods for WOM codes is also provided.
Dynamic Insurance with Private Information and Balanced Budgets

This paper studies a dynamic insurance problem with bilateral asymmetric information and balanced budgets. There are two infinitely-lived agents in our model, both risk averse, and each has an i.i.d. random endowment stream which is unobservable to the other. In each period, each agent must have a non-negative consumption and together they must consume the entire aggregate endowment. Dynamic incentive compatibility in the Nash sense is defined. We give sufficient and necessary conditions for the existence of a constrained efficient contract. We show that a constrained efficient contract can be characterized in a Bellman equation. We demonstrate that the long-run distribution of expected utilities of each agent is not degenerate. We also develop an algorithm for computing the efficient contract and, in a numerical example, we find that the consumption processes of the agents form stationary Markov chains.
A Model for Recruitment and Service - the University of Nevada's Summer Preceptorships in Indian Communities

DESPITE EFFORTS TO INCREASE the numbers of Indians entering or enrolled in the various health professions and occupations during the past few years, their numbers remain far below the proportion that would be representative of this minority in the population and needed to provide adequate health care to a significantly underserved population. Historically, access to the health professions and occupations for Indians has been limited by economic costs, geographic isolation, and deficiencies in their early education. Equally important, however, has been a widespread lack of appropriate role models, as well as cultural support from the Indian community itself for such career choices by its youth. As a result, many Indian students have failed to consider a number of socially and economically desirable health careers. Nevada is the seventh largest State in the nation, covering more than 100,000 square miles. Within it live more than 10,000 Indians who are registered on the tribal rolls of Nevada's 23 reservations and urban colonies. Several thousand others are unregistered, since they reside in urban areas or work as transients. As elsewhere in the nation, Nevada's Indians suffer from poor health and poor health care as measured by nearly every index. An increase in trained health personnel motivated for service to this population undoubtedly would result in significant improvements in these indices.
Heterocyclic diversity: the road to biological activity

In a previous review [1] written for this series I presented an account of some of my experiences during my 25-year tenure with CIBA and then CIBA-Geigy. These reflections emphasized primarily my role in management, especially as it related to my responsibilities as Executive Vice President and Director of Research, and the background related to decisions concerning the research and development process and the decision-making which led to bringing certain medicinal products into the physician’s armamentarium. Several cogent factors associated with organizational matters and operational principles were also stressed. These and other thoughts were presented in a retrospective account and served to summarize my career as a manager of large multi-faceted research and development programs On reflection, what experiences prepared me for this role?
Notes on Economic Warfare

Despite the disaster in Viet Nam, deterrence did play a role in maintaining the peace. The mathematical models of the cold war showed that much. They also showed that deterrence could generate an unbounded arms race.
Networks as Public Infrastructure: Externalities, Efficiency, and Implementation

First, a noncooperative model of network formation is investigated where link formation is one-sided and information flow is two-way. For that model, the relationship between different notions of efficient networks is studied: Pareto-optimal networks on the one hand and welfare-maximizing networks on the other hand. Strategic network formation is compared with funding schemes for public goods. Second, we extend the model and review earlier findings how a preexisting network affects existence of Nash equilibria and efficiency of Nash equilibrium outcomes of the strategic network formation game. It can foster or prohibit existence of Nash equilibria. It can improve or worsen equilibrium welfare. Finally, we treat the preexisting network as public infrastructure and design and analyze a subscription game for the public provision of that infrastructure.
Watch your constants: malicious Streebog

In August 2012, the Streebog hash function was selected as the new Russian cryptographic hash standard (GOST R 34.11-2012). In this study, the authors investigate the new standard in the context of malicious hashing and present a practical collision for a malicious version of the full hash function. In particular, they apply the rebound attack to find three solutions for three different differential paths for four rounds. Then, using the freedom of the round constants they connect them to obtain a collision for the 12 rounds of the compression function. Additionally, and because of the simple processing of the counter, they bypass the barrier of the checksum finalisation step and transfer the compression function collision to the hash function output with no additional cost. The presented attack has a practical complexity and is verified by an example. Although the results of this study may not have a direct impact on the security of the current Streebog hash function, it presents an urge for the designers to publish the origin of the used parameters and the rational behind their choices in order for this function to gain enough confidence and widespread adoption by the security community.
Stereoselective Synthesis of Quaternary Center Bearing Azetines and Their β-Amino Acid Derivatives

We describe here the use of a stable, four-membered azetine heterocycle for the preparation of highly substituted beta-amino acid derivatives. Imidazolidinone chiral auxiliaries were found to eliminate a competitive reaction pathway that had been present under previously reported conditions for azetine synthesis. The ephedrine derived imidazolidin-2-one 21 was allowed to react as its chlorotitanium enolate with O-methyl or -benzyl oximes under optimized conditions to gain improved access to azetines at the gram scale. The azetines were further found to undergo alkylation with complete diastereocontrol, affording the creation of a quaternary center. Subsequent ring opening with benzoyl chloride and auxiliary cleavage provided the corresponding beta2,2,3-amino carbonyl derivatives in good yields.
Normal p-complements for finite groups

The minimal number of generators of the group Q is denoted m(s). We define d(B) = max m(s) where ‘21 ranges over all the abelian subgroups of EJ and we let J(cli) be the subgroup generated by all the abelian subgroups ‘u of (5 which satisfy d(B) = m(a). Clearly, if J(S) c R c Q, then J(B) is a characteristic subgroup of R, J(B) char Ji. Z(G) denotes the center of 8 and / 0, jr, is the order of a SD-subgroup of Q.