cssi/SciSciGPT-SciSciNet huggingface dataset:
Retention strategies in longitudinal studies with emerging adults.

Purpose/objectives The purpose of this report was to describe retention strategies that were useful and those that were not in a longitudinal study of emerging adults. Background A longitudinal study examining the transition to young adulthood among emerging adults with type 1 diabetes, which had success in retention, provided the context for describing retention strategies. Rationale A challenge in longitudinally designed studies is retention of participants because the loss decreases power for statistical analysis. Given that emerging adulthood is a period of instability, retention is particularly challenging among this population. However, longitudinal studies are the best way to understand developmental changes, and it is also important to increase our knowledge of health outcomes during emerging adulthood. Description Retention strategies used in the study are described, including promoting a positive relationship with participants, maintaining contact with participants, having a study staff with good interpersonal skills, using incentives, conveying respect for participants, and using user-friendly data collection. Outcomes Useful strategies to promote a positive relationship included sending cards and newsletters to participants, maintaining consistency of contact person, and expressing appreciation for participant's time and effort. Useful strategies for maintaining contact with participants included obtaining contact information at every data collection point, maintaining birth dates and chart numbers in tracking databases, monitoring returned mail, and using Web search engines. Other useful strategies were providing incentives to participants, employing staff with good interpersonal skills, providing participants with choices when appropriate, and using user-friendly data collection. One strategy, using contests, was not found useful. Conclusions Despite the challenges of conducting longitudinally designed studies with emerging adults, multiple retention strategies can be used that are useful to retention. Implications It is feasible to conduct longitudinal studies with emerging adults despite the challenges.
The Changing Commute: A Case-study of the Jobs-Housing Relationship over Time

Commuting patterns between home and work were studied among 30 000 employees of Kaiser Permanente, a major health care provider in Southern California. The study tracked the differences between home and work location among employees over 6 years by analysing employee records and responses to a survey of over 1500 of the workers. It was found that work trip lengths had in general not grown over the 6 year period. Growth of the work force had contributed more to the growth in local traffic congestion than had a lengthening of the work trip over time. The automobile remains the dominant mode of travel between home and work for these employees, and choices of residential location were found to be based upon many factors in addition to the home-work separation, such as quality of neighbourhood and schools and perceived safety.
Multilayer-coated mirrors as power filters in synchrotron radiation beamlines

Multilayer-coated mirrors, rather than conventional total-reflection mirrors, have been proposed as a means to reduce power incident on the first optical element of high resolution monochromators. We have designed, fabricated, installed and characterized a multilayer pre-mirror specifically for the 800 to 4000 eV range for the X24-A bending magnet beamline at the National Synchrotron Light Source. Various aspects of this application are discussed, including power and thermal considerations, beamline layout considerations and constraints, choice of multilayer materials and substrate, and techniques to ensure lateral uniformity of the multilayer. Results of a preliminary characterization of a mirror coated with a SiC/V multilayer and installed in the beamline are also discussed. 9 refs., 5 figs.
Global Aging and the Rise of the Developing World

No challenge will more thoroughly dominate the evolution of global finance, politics, and society during the next half–century than the fallout from the simultaneous aging of the industrial countries plus Russia and Eastern Europe and, after 2020, much of East Asia and Latin America as well. This tectonic upheaval will force the fundamental restructuring of developed–world social and trade policies and shift the locus of global dynamism to India, China and other emerging market countries.
Triviality and the Higgs mass lower bound

In the minimal Standard Model, it is commonly believed that the Higgs mass cannot be too small, otherwise Top quark dynamics makes the Higgs potential unstable. Although this Higgs mass lower bound is relevant for current phenomenology, we show that the Higgs vacuum instability in fact does not exist and only appears when treating incorrectly the cut-off in the renormalization of a trivial theory. We also demonstrate how to calculate correctly the regulator-dependent Higgs mass lower bound.
Distance-based phylogenetic methods around a polytomy

Distance-based phylogenetic algorithms attempt to solve the NP-hard least-squares phylogeny problem by mapping an arbitrary dissimilarity map representing biological data to a tree metric. The set of all dissimilarity maps is a Euclidean space properly containing the space of all tree metrics as a polyhedral fan. Outputs of distance-based tree reconstruction algorithms such as UPGMA and neighbor-joining are points in the maximal cones in the fan. Tree metrics with polytomies lie at the intersections of maximal cones. A phylogenetic algorithm divides the space of all dissimilarity maps into regions based upon which combinatorial tree is reconstructed by the algorithm. Comparison of phylogenetic methods can be done by comparing the geometry of these regions. We use polyhedral geometry to compare the local nature of the subdivisions induced by least-squares phylogeny, UPGMA, and neighbor-joining when the true tree has a single polytomy with exactly four neighbors. Our results suggest that in some circumstances, UPGMA and neighbor-joining poorly match least-squares phylogeny.
NONLOCALITY AND GRAVITY-INDUCED CP VIOLATION

We consider a space–time dependent relative phase between the right- and left-handed spinors and show that it results in a violation of locality in the presence of gravity once the demand of parity covariance is dropped. This violation of locality is such that it readily interprets itself as a gravity-induced CP violation, and at the same time confirms an earlier remark by Wigner that a representation space carries more information than a wave equation. This happens, as Kirchbach has noted, because while the dimensionality of an irreducible representation space does not depend upon the concrete realization of the symmetry generators, Noether currents (Dirac, versus Majorana, versus the CP violating construct presented here) do. The gravity-induced CP violation provides a dynamical reason on how a neutron star carrying its baryon and lepton numbers can collapse into a black hole and loose information on the latter characteristics.
Estimates of surface heat flux from sodar and laser scintillation measurements in the unstable boundary layer

Measurements of acoustic backscatter in the lower planetary boundary layer and optical line-of-sight scintillation in the surface layer are each used to compute sensible heat fluxes in the unstable surface layer. Comparisons with simultaneous low-level point measurements by eddy correlation show good agreement, indicating that remote-sensing methods can be successful over less homogeneous terrain where conventional surface layer measurement techniques are less accurate. Corrections to take into account the effects of humidity fluctuations are found necessary in order to achieve accuracies within 10%. Free convection is assumed to permit interpretation of the sodar data, while either forced or free convection is assumed for the scintillation data. A systematic overestimate of heat fluxes is found from sodar measurements made during the morning, when the height of the convectively mixed layer is increasing rapidly.
Effects of capillary heterogeneity on vapor-liquid counterflow in porous media

Based on a continuum description, the effect of capillary heterogeneity, induced by variation in permeability, on the steady state, countercurrent, vapor-liquid flow in porous media is analyzed. It is shown that the heterogeneity acts as a body force, that may enhance or diminish gravity effects on heat pipes. Selection rules that determine the steady states reached in homogeneous, gravity-driven heat pipes are also formulated. It is shown that the infinite'' two-phase zone may terminate by a substantial change in the permeability somewhere in the medium. The two possible sequences, liquid - liquid dominated - dry, or liquid - vapor dominated - dry find applications in geothermal systems. Finally, it is shown that although weak heterogeneity affects only gravity controlled flows, stronger variations in permeability can give rise to significant capillary effects.
Mechanical Stability Test for Hevea Latex

Abstract The mechanical stability test is a rapid, simple method of estimating the colloidal stability or quality of Hevea latex by high-speed stirring. Latex particles start to agglomerate as soon as the peripheral speed of the agitator reaches a certain minimum value. Progressive flocculation continues until mechanical coagulation occurs. The end point is defined as the time in seconds required to coagulate 0.5 to 1.0 per cent of the total solids. If the shear is constant, the time is proportional to the colloidal stability, which depends upon the interfacial film between the latex particles and the serum. The mechanical stability time depends critically on the size, the total solids, and the temperature of sample.
Impact of US biofuel policy on US corn and gasoline price variability

Abstract Despite a large number of studies that examine the influence of biofuels and biofuel policy on commodity prices, the impact of biofuel policy on commodity price variability is poorly understood. A good understanding of biofuel policy’s impact on price variability is important for mitigating food insecurity and assisting policy formation. We examine how U.S. ethanol policies such as the Renewable Fuel Standard (RFS) mandates and the blend wall affect the price variability of corn and gasoline. We first present an analytical and graphical framework to identify the effect and then use stochastic partial equilibrium simulation to measure the magnitude of the impacts. We show that RFS mandates and the blend wall both reduce the price elasticity of demand for corn and gasoline and therefore increase the price variability when supply shocks occur to the markets. This has important implications for policy actions with respect to maintaining or changing the current RFS mandates and/or blend wall in the US.
COMPUTATIONAL GEOMETRY COLUMN 23

Three open problems on tetrahedralizations are described: Does bisection refinement keep solid angles bound away from zero? Can a tetrahedralization be frozen with respect to flips? Do points in convex position have a Hamiltonian tetrahdralization?
Emotional stress and infertility

THE term ‘stress’ is here taken to mean “the internal or resisting force brought into being in the human organism by interaction with the environment” [l]. In stress disorders in general it is the interaction between man and his fellow-beings which produces illness; in infertility it is the quality of the relationship to the spouse, as well as to the rest of the family, which is of great importance. In many disorders this relationship may be obvious but with infertility it is often obscure.
Fast Analogue Multipliers with Field-Effect Transistors

The solution time of analogue multipliers using field-effect transistors is investigated. This time is ultimately limited by the charging time of the field-effect transistor junction. In typical devices suitable for analogue multiplication the charging time is found to be about 10-20 nsec for a multiplication error of less than one percent. A four quadrant pulse amplitude multiplier circuit is described, whose solution time is equal to the field-effect transistor charging time.
Trust in Agency

Existing models of the principal–agent relationship assume the agent works only under extrinsic incentives. However, many observed agency contracts take the form of a fixed payment. For such contracts to work, the principal must trust the agent to work in the absence of incentives. I show that agency fosters the advent of intrinsic motivation and trustworthy behavior. Three distinct motivational schemes are analyzed: norms, ethical standards, and altruism. I identify conditions under which these mechanisms arise and show how they promote trust. The analysis alters several important predictions of conventional models: (1) Better outcomes may ensue in highly uncertain environments; (2) the principal is better off the more the agent is risk averse; and (3) larger equilibrium extrinsic incentives need not be associated with larger effort or larger total surplus.
Honey, the Currency Union Effect on Trade Hasn’t Blown Up

as the value of real bilateral trade between‘countries’ i and j at time t, CU is a dummy variable which is unity if i and j sharethe same currency at time t, Z is a vector of controls given by an augmentedgravity model, c are the associate nuisance coefficients, and is a (hopefully)well-behaved residual. My chief finding was that was large and robust; mypoint estimate was ‹1:2, implying that currency union is associated with atripling (since exp(1.2)ˇ3) of trade.In his paper in this issue, Volker Nitsch provides three pieces of value-added.First he finds and corrects a number of data errors in my original data set. Second,he shows that adding extra controls to my empirical setup, disaggregating bycurrency unions, and adjusting for missing data affects the results. He concludesthat the effect of currency union on trade is smaller than my original estimates,has not been reliably estimated, and may be zero.
C-H arylation of pyridines: high regioselectivity as a consequence of the electronic character of C-H bonds and heteroarene ring.

We report a new catalytic protocol for highly selective C–H arylation of pyridines containing common and synthetically versatile electron-withdrawing substituents (NO2, CN, F and Cl). The new protocol expands the scope of catalytic azine functionalization as the excellent regioselectivity at the 3- and 4-positions well complements the existing methods for C–H arylation and Ir-catalyzed borylation, as well as classical functionalization of pyridines. Another important feature of the new method is its flexibility to adapt to challenging substrates by a simple modification of the carboxylic acid ligand or the use of silver salts. The regioselectivity can be rationalized on the basis of the key electronic effects (repulsion between the nitrogen lone pair and polarized C–Pd bond at C2-/C6-positions and acidity of the C–H bond) in combination with steric effects (sensitivity to bulky substituents).
MEXICO'S FINANCIAL SECTOR CRISIS: PROPAGATIVE LINKAGES TO DEVALUATION*

The sharp 1994 Mexican peso devaluation was followed by a financial-sector crisis, forcing the Mexican government to retake control of several banks and to grant substantial assistance to many others. This paper tests several hypotheses concerning the impact of devaluation. First, event-study methodology is used to test whether some sectors of Mexican economy were 'devaluation-gaining' while others were 'devaluation-losing'. Second, we test whether devaluation shocks were transmitted to the financial sector through the liability side versus the asset side of bank balance sheets. Our results indicate the importance of asset diversification.
Stereoselective total synthesis of topographically constrained designer amino acids: 2′, 6′-dimethyl-β-methyltyrosines

Abstract The constrained aromatic α-amino acid 2′, 6′-dimethyl-β-methyl tyrosine (Figure 1) was designed to provide specific local constraints to peptides or peptide mimetics. We report here methods for the total asymmetric synthesis of all four stereoisomers. The precursors used were α,β-unsaturated acid derivatives, (2E) 3-(4′)-methoxy-2′,6′-dimethyl-2-propenoic acid (5) and crotonyl chloride (6). In order to introduce chirality at both the α- and the β-positions of the amino acids, optically pure 4-phenyl-2-oxazolidinones (Xc) were coupled to 5 and 6. The key steps for the synthesis were: (1) a Michael type addition using either methylmagnesium bromide/copper (I) bromide-dimethyl sulfide complex or 4-methoxy-2,6-dimethylphenylmagnesium bromide/copper (I) bromide-dimethyl sulfide complex as nucleophiles; (2) an asymmetric bromination of the α-position of the N-acyloxazolidinones using di(n-butyl)boron triflate/DIEA/NBS as reagents at low temperature. In both cases, the stereoselectivies and yields were excellent; (3) amination was achieved in nearly quantative yield by treating the bromides with azide exchange resin via an SN2 mechanism. (Electrophilic azidation using 2,4,6-triisopropylsulfonyl azide also was achieved). The excellent stereoselectivity (80–98% ee/de) and overall yield (30–60%) made these optically pure amino acids available in amounts practical for peptide synthesis and further conformational and structure-activity relationship studies of various peptide analogues.
Some boundedness results for systems of two rational difference equations

We study kth order systems of two rational difference equations $$ x_n = \frac{{\alpha + \sum\nolimits_{i = 1}^k {\beta _i x_{n - 1} + } \sum\nolimits_{i = 1}^k {\gamma _i y_{n - 1} } }} {{A + \sum\nolimits_{j = 1}^k {B_j x_{n - j} + } \sum\nolimits_{j = 1}^k {C_j y_{n - j} } }}, y_n = \frac{{p + \sum\nolimits_{i = 1}^k {\delta _i x_{n - i} + } \sum\nolimits_{i = 1}^k {\varepsilon _i y_{n - i} } }} {{q + \sum\nolimits_{j = 1}^k {D_j x_{n - j} + } \sum\nolimits_{j = 1}^k {E_j y_{n - j} } }} n \in \mathbb{N} $$ . In particular, we assume non-negative parameters and non-negative initial conditions, such that the denominators are nonzero. We develop several approaches which allow us to extend well known boundedness results on the kth order rational difference equation to the setting of systems in certain cases.
A note on strong negative partition relations

We analyze a natural function definable from a scale at a singular cardinal, and using this function we are able to obtain quite strong negative square-brackets partition relations at successors of singular cardinals. The proof of our main result makes use of club-guessing, and as a corollary we obtain a fairly easy proof of a difficult result of Shelah connecting weak saturation of a certain club-guessing ideal with strong failures of square-brackets partition relations. We then investigate the strength of weak saturation of such ideals and obtain some results on stationary reflection.
A novel route to the geissoschizine skeleton: The influence of ligands on the diastereoselectivity of the Heck cyclization

Abstract A concise, novel route to the geissoschizine skeleton has been developed. The key step involves a Heck cyclization reaction, which was found to lead to opposite diastereomers, (±)- 8 or (±)- 9 , depending on the reaction conditions.
Subterranean transport of radon and elevated indoor radon in hilly karst terrains

Abstract Subterranean networks of cavities and fissures can present circulatory systems facilitating convective and advective transport of radon-bearing air. Evidence points to aerostatic pressure differentials being the principal driving force for subterranean transport of radon in some hilly limestone terrains of the southern Appalachians; differences between the underground and outside air temperatures, and the concomitant differences in air density, appear to be the dominant factor in producing the differences in aerostatic pressure. Examples are presented of houses experiencing elevated indoor levels as a consequence of being built on top of and apparently communicating with such subterranean systems. The location of a house near the upper or lower end of a subterranean circulatory system can result in amplification of indoor radon levels in winter or summer, respectively. These phenomena have been studied in and around houses located in the hilly karst areas of Huntsville, AL, and Oak Ridge, TN.
Smoothed analysis of tensor decompositions

Low rank decomposition of tensors is a powerful tool for learning generative models. The uniqueness results that hold for tensors give them a significant advantage over matrices. However, tensors pose serious algorithmic challenges; in particular, much of the matrix algebra toolkit fails to generalize to tensors. Efficient decomposition in the overcomplete case (where rank exceeds dimension) is particularly challenging. We introduce a smoothed analysis model for studying these questions and develop an efficient algorithm for tensor decomposition in the highly overcomplete case (rank polynomial in the dimension). In this setting, we show that our algorithm is robust to inverse polynomial error -- a crucial property for applications in learning since we are only allowed a polynomial number of samples. While algorithms are known for exact tensor decomposition in some overcomplete settings, our main contribution is in analyzing their stability in the framework of smoothed analysis. Our main technical contribution is to show that tensor products of perturbed vectors are linearly independent in a robust sense (i.e. the associated matrix has singular values that are at least an inverse polynomial). This key result paves the way for applying tensor methods to learning problems in the smoothed setting. In particular, we use it to obtain results for learning multi-view models and mixtures of axis-aligned Gaussians where there are many more "components" than dimensions. The assumption here is that the model is not adversarially chosen, which we formalize by thinking of the model parameters as being perturbed. We believe this an appealing way to analyze realistic instances of learning problems, since this framework allows us to overcome many of the usual limitations of using tensor methods.
A MR-TRUS Registration Method for Ultrasound-Guided Prostate Interventions.

In this paper, we reported a MR-TRUS prostate registration method that uses a subject-specific prostate strain model to improve MR-targeted, US-guided prostate interventions (e.g., biopsy and radiotherapy). The proposed algorithm combines a subject-specific prostate strain model with a Bspline transformation to register the prostate gland of the MRI to the TRUS images. The prostate strain model was obtained through US elastography and a 3D strain map of the prostate was generated. The B-spline transformation was calculated by minimizing Euclidean distance between MR and TRUS prostate surfaces. This prostate stain map was used to constrain the B-spline-based transformation to predict and compensate for the internal prostate-gland deformation. This method was validated with a prostate-phantom experiment and a pilot study of 5 prostate-cancer patients. For the phantom study, the mean target registration error (TRE) was 1.3 mm. MR-TRUS registration was also successfully performed for 5 patients with a mean TRE less than 2 mm. The proposed registration method may provide an accurate and robust means of estimating internal prostate-gland deformation, and could be valuable for prostate-cancer diagnosis and treatment.
Subband finite state scalar quantization

A new image-coding algorithm that exploits the relationship between various subbands of an image is presented in this correspondence. Using local variance for state selection and uniform threshold quantizers on subbands, we have achieved a reduction in quantization noise compared to other published techniques for Lena at various bit rates.
Thermodynamics of the α,β and γ polymorphs of AlH3

Abstract The thermodynamics of the α , β and γ polymorphs of AlH3 were determined using differential scanning calorimetry and ex situ X-ray diffraction. These results demonstrate that at around 100 ° C the decomposition of the β and γ polymorphs occurs by an initial phase transition to the α polymorph followed by decomposition of the α phase. The total heat evolved during the β → α transition is 1.5 ± 0.4 kJ/mol AlH3 and 2.8 ± 0.4 kJ/mol AlH3 during the γ → α transition. The transformation to the α phase is exothermic and is therefore likely to occur spontaneously at room temperature. A formation enthalpy of approximately − 10 kJ/mol AlH3 was measured for α -AlH3, which is in good agreement with previous experimental and calculated results.
Reliability Analysis of Uniaxially Ground Brittle Materials

The fast fracture strength distribution of uniaxially ground, alpha silicon carbide was investigated as a function of grinding angle relative to the principal stress direction in flexure. Both as-ground and ground/annealed surfaces were investigated. The resulting flexural strength distributions were used to verify reliability models and predict the strength distribution of larger plate specimens tested in biaxial flexure. Complete fractography was done on the specimens. Failures occurred from agglomerates, machining cracks, or hybrid flaws that consisted of a machining crack located at a processing agglomerate. Annealing eliminated failures due to machining damage. Reliability analyses were performed using two and three-parameter Weibull and Batdorf methodologies. The Weibull size effect was demonstrated for machining flaws. Mixed mode reliability models reasonably predicted the strength distributions of uniaxial flexure and biaxial plate specimens.
The latency information theory revolution, part III: knowledge-unaided power-centroid adaptive radar

Knowledge unaided power centroid (KUPC) adaptive radar and its latency information theory (LIT) roots are reviewed in this third paper of a three paper series. LIT is the universal guidance theory for efficient system designs that has inherently surfaced from the confluence of five ideas. They are: 1) The source entropy and channel capacity performance bounds of Shannon's mathematical theory of communication; 2) The latency time (LT) certainty of Einstein's relativity theory; 3) The information space (IS) uncertainty of Heisenberg's quantum physics; 4) The black hole Hawking radiation and its Boltzmann thermodynamics entropy S in SI J/K; and 5) The author's 1978 conjecture of a structural-physical LT-certainty/IS-uncertainty duality for stochastic control. LIT is characterized by a four quadrants revolution. While the first and third quadrants are concerned with the life time of physical signal movers and the life space of physical signal retainers, respectively, the second and fourth quadrants are about the intelligence space of mathematical signal sources and the processing time of mathematical signal processors, respectively. The four quadrants of LIT are assumed to be physically independent with their system design methodologies guided by dualities and performance bounds. Moreover, all the LIT quadrants are bridged by statistical physics, inclusive of a recently discovered time dual for thermodynamics that has been named lingerdynamics. The theoretical and practical relevance of LIT has already been demonstrated using real-world control, physics, biochemistry and the KUPC adaptive radar application that is reviewed in this paper. KUPC adaptive radar is a technique that falls within the fourth quadrant of LIT, and is thus a mathematical signal processing technique whose goal is the efficient detection of moving targets in real-world taxing environments. As is highlighted in this review KUPC adaptive radar is found to come relatively close to the signal to interference plus noise ratio (SINR) radar performance of DARPA's knowledge-aided sensory signal processing expert reasoning (KASSPER) even though it is knowledge unaided.
Associative capabilities for mass storage through array organization

Since computers first came into wide usage, digital systems designers have been intrigued by the possibilities of associative or content addressable memories. The concept is quite easy to understand; whereas, in the conventional case, the address is furnished to the memory and the data stored at that location is the expected result, in the associative reference, the data is furnished and the expected result is a list of all addresses which contain matching data. Up to now, however, the physical systems which exhibit the requisite symmetry to realize this concept have been necessarily very costly because the commonly used, low cost, random access memories do not easily lend themselves to this new operation. Those digital systems designers who predicted widespread use of associative memories by the late 1960's are found in retrospect to have seriously underestimated the difficulty in implementing thin magnetic film or superconducting memory systems, on which these forecasts heavily depended.
Using Realist Social Theory to Explain Project Outcomes

In researching IS phenomena, many different theoretical lenses have been advanced. This paper proposes the use of Margaret Archer's Morphogenetic Approach to Analytical Dualism MAAD as a social theoretic approach to explain why social phenomena may occur in a case study. This paper provides a brief overview to MAAD, providing a description of its tenets and methodology for use in an empirical study. As an example, the author applies MAAD to the implementation of Lotus Notes in the Alpha consulting organization as reported by Orlikowski 2000. This approach shows that the differential success of the implementation efforts in the different organizations was due to the diverse cultures and possible experiences with technology found in those organizations. This example shows that the use of this social theory can provide explanatory purchase where social phenomena are involved. For practitioners, it suggests that structural analysis at the beginning of a project may provide direction as to how to make the project more successful.
Orbital coplanarity in solar-type binary systems: Implications for planetary system formation and detection

The equatorial inclinations of solar-type stars within visual binary systems are computed by combining v sin i measurements with rotational period information, or with expected rotational velocities based upon the age of the star in question. These inclinations are then compared with the orbital inclinations of the systems to test the alignment between the equatorial and orbital planes, and how the tendency for or against coplanarity varies as a function of parameters such as spectral type, separation, eccentricity, etc. The results are extended to planetary systems in order to determine the appropriateness of basing planetary search strategies upon a parent star's equatorial inclination, and to address issues in planetary system formation and evolution, including the stability of planetary orbits within binary systems. During the course of this project new or improved v sin i measurements are made for over 30 solar-type stars within binary systems, and (for the purposes of the study) tentative orbits are computed for thirteen long-period systems. The results suggest that approximate coplanarity between the equatorial and orbital planes exists solar-type binary systems with separations less than 30-40 AU. The coplanarity tendency, as well as this 'critical separation,' is not significantly affected by most of the other parameters studied. The one significant exception occurs with hierarchical multiple systems, where noncoplanarity may exist at relatively small separations. If it is assumed that planetary distances in our solar system are typical, the results suggest there is no reason to expect planets to orbit in planes significantly different from that of the parent star's equator, in turn suggesting that planetary formation models and search strategies dependent upon this assumption are valid from this standpoint. The results also suggest that noncoplanarity between the components of a binary system is not a significant issue in addressing the stability of planetary orbits within the system.
Classical description of deuteron stripping in a coulomb field

Abstract The Coulomb stripping of deuterons is discussed in a simple semi-classical approximation and a closed form for the proton angular distribution is obtained.
Quantitative tests of color evaporation: charmonium production

Abstract The color evaporation model simply states that charmonium production is described by the same dynamics as D D production, i.e., by the formation of a colored c c pair. Its color happens to be bleached by soft final-state interactions. We show that the model gives a complete picture of charmonium production including low-energy production by proton, photon and antiproton beams, and high-energy production at the Tevatron and HERA.
Circuit Master: turnkey software for the introductory electrical engineering curriculum

A turnkey software system for the introductory electrical engineering curriculum is described in detail from a user's perspective. The system, Circuit Master, provides a structured, interactive, menu-driven environment that allows students to explore basic concepts in circuit and signal theory without requiring a background in computer programming. The system's interactive user interface and visual presentation format simultaneously display relationships between circuit components, pole-zero patterns. Bode plots, initial conditions, input/output signal waveforms, and input/output signal spectra for periodic and aperiodic signals. Simultaneous display of information for two sets of circuit components allows physical relationships, parametric changes, and sensitivity issues to be examined easily. >
Planetary magnetic fields

Abstract Present knowledge and modern theories of the Earth's main magnetic field are outlined and the state of knowledge of the magnetic fields of the other planets is sketched.
On the isoperimetric constant of symmetric spaces of noncompact type

From this result one can easily deduce I (H) = n 1. For a detailed discussion of Cheegers constant and related results, one can consult [Cha, Chapter 6]. In general, it is very di¢ cult to know if the isoperimetric constant is positive or not and it is almost impossible to compute it explicitly if it is known to be positive. In this short note, we prove that the isoperimetric constant is positive for all symmetric spaces of noncompact type and compute it explicitly. Let f M; g be a Cartan-Hadamard manifold (i.e. complete, simply-connected with nonpositive curvature) and Sf M its unit tangent bundle. For any p 2 M and u 2 Spf M we have a nonnegative symmetric operator Ru : Tpf M ! Tpf M de ned by
Design and construction of the CDF central outer tracker

Abstract A new tracking chamber, the Central Outer Tracker (COT), has been built as part of the upgrade of the CDF detector at the Fermilab Tevatron. The COT is a cylindrical open-cell drift chamber, segmented into 96 layers. High voltage and readout electronics are mounted on the chamber endplates, providing timing and charge deposition information. The COT is designed to operate in the high-luminosity environment of the upgraded Tevatron. With the addition of the Main Injector and the Recycler Ring, the Tevatron will be capable of provinding luminosity as high as 2×10 32 cm −2 s −1 at a bunch spacing of 132 ns. We discuss the design of the detector, as well as the assembly. Construction of the COT was completed in Spring 2000, and the first data will be taken during a commissioning run in late Summer 2000.
Toxoplasma gondii Lysine Acetyltransferase GCN5-A Functions in the Cellular Response to Alkaline Stress and Expression of Cyst Genes

Parasitic protozoa such as the apicomplexan Toxoplasma gondii progress through their life cycle in response to stimuli in the environment or host organism. Very little is known about how proliferating tachyzoites reprogram their expressed genome in response to stresses that prompt development into latent bradyzoite cysts. We have previously linked histone acetylation with the expression of stage-specific genes, but the factors involved remain to be determined. We sought to determine if GCN5, which operates as a transcriptional co-activator by virtue of its histone acetyltransferase (HAT) activity, contributed to stress-induced changes in gene expression in Toxoplasma. In contrast to other lower eukaryotes, Toxoplasma has duplicated its GCN5 lysine acetyltransferase (KAT). Disruption of the gene encoding for TgGCN5-A in type I RH strain did not produce a severe phenotype under normal culture conditions, but here we show that the TgGCN5-A null mutant is deficient in responding to alkaline pH, a common stress used to induce bradyzoite differentiation in vitro. We performed a genome-wide analysis of the Toxoplasma transcriptional response to alkaline pH stress, finding that parasites deleted for TgGCN5-A fail to up-regulate 74% of the stress response genes that are induced 2-fold or more in wild-type. Using chromatin immunoprecipitation, we verify an enrichment of TgGCN5-A at the upstream regions of genes activated by alkaline pH exposure. The TgGCN5-A knockout is also incapable of up-regulating key marker genes expressed during development of the latent cyst form, and is impaired in its ability to recover from alkaline stress. Complementation of the TgGCN5-A knockout restores the expression of these stress-induced genes and reverses the stress recovery defect. These results establish TgGCN5-A as a major contributor to the alkaline stress response in RH strain Toxoplasma.
Submicroscopic Structure of Cellulose from Nitrogen-Sorption Measurements

When cotton linters were soaked in cold 10% sodium hydroxide, washed and neutralized, transferred successively to methyl alcohol and benzene, and carefully dried at reduced pressure, a surface area as great as 71.3 sq. m. per g. was obtained by the Brunauer-Emmett-Teller tech nique. Previously obtained areas for untreated cotton were all less than 1 sq. m. per g. Linters carried through the above steps after soaking in water instead of in alkali had areas as great as 47.3 sq. m. per g. When the alkali-treated sample was conditioned in water vapor to a 3.3% gain in weight, the surface decreased to 31.6 sq. m. per g.; further conditioning to an 11.0% gain in weight decreased the surface to 2.1 sq. m. per g.The isotherms of the treated samples showed strong hysteresis, while the isotherms of untreated cotton showed little or no hysteresis.Calculations of pore-size distribution by the method of Wheeler and Shull indicated that these materials have rather narrow distribution ranges, the alkali-treated material...
Metabolism of thioctic acid in algae.

Thioctic acid labeled with sulfur-35 has been prepared and i t s metabolism b y algae has been studied. It i s converted by the algae into a number of forms, all of which upon hydrolysis yield either the disulfide o r i t s sulfoxide. One of these constituted the major portion of the labeled material in the chloroplasts. Aerobic metabolism for some minutes i s required to produce this form. Preliminary studies of the chemical nature of this form suggest i t to be esterified on the carboxyl group with a moiety of very high lipid solubility.
Two simple W′ models for the early LHC

W′ gauge bosons are good candidates for early LHC discovery. We define two reference models, one containing a W R ′ and one containing a W L ′, which may serve as “simplified models” for presenting experimental results of W′ searches at the LHC. We present the Tevatron bounds on each model and compute the constraints from precision electroweak observables. We find that indirect low-energy constraints on the W L ′ are quite strong. However, for a W R ′ coupling to right-handed fermions there exists a sizeable region in parameter space beyond the bounds from the Tevatron and low-energy precision measurements where even 50 pb−1 of integrated LHC luminosity are sufficient to discover the W R ′. The most promising final states are two leptons and two jets, or one lepton recoiling against a “neutrino jet”. A neutrino jet is a collimated object consisting of a hard lepton and two jets arising from the decay of a highly boosted massive neutrino.
Polynomial-time Membership Comparable Sets

This paper studies a notion called polynomial-time membership comparable sets. For a function $g$, a set $A$ is polynomial-time $g$-membership comparable if there is a polynomial-time computable function $f$ such that for any $x_1, \cdots, x_m$ with $m \geq g(\max\{ |x_1|, \cdots, |x_m| \})$, outputs $b \in \{0,1\}^m$ such that $(A(x_1), \cdots, A(x_m)) \neq b$. The following is a list of major results proven in the paper. 1. Polynomial-time membership comparable sets construct a proper hierarchy according to the bound on the number of arguments. 2. Polynomial-time membership comparable sets have polynomial-size circuits. 3. For any function $f$ and for any constant $c>0$, if a set is $\leq^p_{f(n)-tt}$-reducible to a P-selective set, then the set is polynomial-time $(1+c)\log f(n)$-membership comparable. 4. For any $\cal C$ chosen from $\{ {\rm PSPACE, UP, FewP, NP, C_{=}P, PP, MOD_{2}P, MOD_{3}}, \cdots \}$, if $\cal C \subseteq {\rm P-mc}(c\log n)$ for some $c<1$, then $\cal C = {\rm P}$. As a corollary of the last two results, it is shown that if there is some constant $c<1$ such that all of $\cal C$ are polynomial-time $n^c$-truth-table reducible to some P-selective sets, then $\cal C = {\rm P}$, which resolves a question that has been left open for a long time.
Shape-function independent relations of charmless inclusive B-decay spectra

A leading-power factorization formula for weight functions relating the →Xsγ photon spectrum to arbitrary partial decay rates in →Xu l− is derived. These weight functions are independent of the hadronic shape function and allow for the determination of |Vub| in a model-independent way. We calculate the weight function in renormalization-group improved perturbation theory to complete next-to-next-to leading order at the jet scale μi2 ~ mbΛQCD and to next-to leading order at the hard scale μh ~ mb. First-order power corrections are also included, where a model-dependence enters via the appearance of subleading hadronic shape functions.
Instability of nonuniform density free shear layers with a wake profile

The linear spatial instability characteristics of both uniform and nonuniform density plane mixing layers were investigated taking into account the wake component of the initial velocity profile. Two unstable modes were found. In the shear layer mode, the growth of the unstable disturbance leads to the usual Kelvin-Helmholtz rollup pattern, whereas in the wake mode, rollup patterns resemble those in wake flows
Founding family ownership and the selection of industry specialist auditors

SYNOPSIS: This study examines how family firms' unique ownership structure and agency problems affect their selection of industry-specialist auditors. Using data from Standard & Poor's (S&P) 1500 firms, the results show that family firms are more likely to appoint industry-specialist auditors than non-family firms, which suggests that family firms have strong incentives to signal the quality of financial reporting. Additional analysis indicates that due to the potential entrenchment problems, family firms with family member CEOs or with dual-class shares have even a higher tendency to hire industry-specialist auditors to signal their disclosure quality.
A mechanism for persistently naming topological entities in history-based parametric solid models

Abstract One of the fundamental problems in history-based parametric solid modelling systems is to identify topological entities (faces, edges, vertices) of solid models in such a way that the same entities can still be identified after the models have been reevaluated from the sequential history of modelling steps. The Topological ID System, presented in this paper, systematically assigns IDs (names, labels) to topological entities in solid models. When the history of modelling steps is edited and then automatically re-evaluated to produce a new version of the solid model, the IDs of topological entities in the old version of the solid model are mapped to IDs of the corresponding topological entities in the new version of the solid model. This mapping defines the correspondence between topological entities in both models.
Special coordinate basis for order reduction of linear multivariable systems

A method of nested feedback loop decomposition of a given system is developed based on a special coordinate basis which reveals the finite and infinite zero structure of the system. This decomposition leads to a model order reduction procedure by which any arbitrary subset of the system invariant zeros can be retained in the model while the infinite zero structure of the model and the system are one and the same. Thus this method of model order reduction is a method of reducing the dynamic order via the zero structure of the given system. Several examples illustrate the method
The anisoplanatic point-spread function in adaptive optics

The effects of anisoplanatism on the adaptive optics point‐spread function are investigated. A model is derived that combines observations of the guide star with an analytic formulation of anisoplanatism in order to generate predictions for the adaptive optics point‐spread function at arbitrary locations within the field of view. The analytic formulation captures the dependencies of anisoplanatism on aperture diameter, observing wavelength, angular offset, zenith angle, and turbulence profile. The predictions of this model are compared to narrowband 2.12 and 1.65 μm images of a 21" binary (m_v = 7.3, 7.6) acquired with the Palomar adaptive optics system on the 5 m Hale Telescope. Contemporaneous measurements of the turbulence profile made with a DIMM/MASS (differential image motion monitor/multiaperture scintillation sensor) unit are used together with images of the primary to predict the point‐spread function of the binary companion. Predicted companion Strehl ratios are shown to match measurements to within a few percent, whereas predictions based on the isoplanatic angle approximation are highly discrepant. The predicted companion point‐spread functions are shown to agree with observations to 10%. These predictions are used to measure the differential photometry between binary members to an accuracy of 1 part in 10^3, and the differential astrometry to an accuracy of 1 mas. Errors in the differential astrometry are shown to be dominated by differential atmospheric tilt jitter. These results are compared to other techniques that have been employed for photometry, astrometry, and high‐contrast imaging.
Ruthenium catalyzed enyne cycloisomerizations and hydroxycyclizations with skeletal rearrangement

A neutral arene-tethered ruthenium complex was found to be a catalyst precursor for enyne cycloisomerizations and hydroxycyclizations. The observed products were the result of a skeletal rearrangement process, and include an unusual cyclization to form a six-membered ring. Labeling studies on the six-membered ring product are in accord with an electrophilic activation mechanism that proceeds via cationic cyclopropyl carbene intermediates.