cssi/SciSciGPT-SciSciNet huggingface dataset:
Stochastic reachability for control of spacecraft relative motion

The concept of stochastic reachability allows for the assessment, before any maneuvers are initiated, of the probability of successfully implementing a rendezvous or docking procedure for spacecraft. The so-called reach-avoid problem lets us find the probability of reaching a target set while avoiding some unsafe or undesired set, despite uncertainty due to nonlinearity and disturbances. This paper examines two novel methods for the calculation of stochastic reachable sets, and specifically for rendezvous and docking problems. In particular, we examine a) particle (or scenario) approximations to expected values, and b) conversion of the reach-avoid probability to a chance-constrained convex optimization problem. Both methods allow for computation of the reach-avoid set in higher dimensions, as compared to other existing methods for computing stochastic reachable sets. We describe in detail both of these methods, and then apply them to spacecraft relative motion, a four-dimensional problem.
Urban effects on flood plain natural hazards: Wolf River, Tennessee, USA

Abstract The Wolf River and its flood plain in the City of Memphis and Shelby County, TN, have been extensively altered since the flood plain underwent liquefaction during the earthquakes of 1811–1812. Flood plain denudation and aggradation (primarily cut and fill) are documented by subtracting flood plain surface elevations obtained in the 1940s, 1965, 1988, and 2001. The resultant maps, cross-sections, and histograms illustrate the complex history and extreme changes that the flood plain has undergone. As a consequence of these post-1940s changes, liquefaction potential of the flood plain is now very complex; the flood plain's area has locally been diminished by approximately 50%, thereby requiring remapping of the areas that will be inundated by 100- and 500-year floods; and entrenchment of the Wolf River and its flood plain may have increased connectivity between Wolf River water and Shelby County's aquifer.
Situational variability of preschoolers' disfluency: preliminary study.

To determine whether preschoolers' disfluency systematically varies as a function of speaking situation, tape-recorded speech samples were obtained from 3 4-yr.-old nonstutterers in 3 different speaking situations, i.e., in a preschool classroom during free play, in a testing room while they performed certain speaking tasks, and in their homes talking with family members. Comparison of the situations showed that frequency of disfluency systematically varied across situations. This leads to the conclusion that sampling preschoolers' disfluency in only one situation is inadequate for most purposes.
Basaloid squamous carcinoma of the hypopharynx and larynx associated with second primary tumors

Basaloid squamous carcinoma is believed to be a histologically distinct variant of squamous cell carcinoma of the neck region with 11 cases reported. Two cases arising in the pyriform fossa and vallecula are reported, both of which were associated with second primary malignant tumors: esophageal small cell carcinoma and palatal squamous cell carcinoma, respectively. The authors suggest that basaloid squamous carcinoma may be associated with a high incidence of second primary tumors in the upper gastrointestinal tract or larynx.
Engineering careers, job rotation, and gatekeepers in Japan and the United States

Abstract Japan's employment system is generally characterized as involving infrequent moves between firms, but regular and systematic transfers within the firm. This system might be expected to result in Japanese engineers having smaller interfirm networks of professional contacts than Americans. This could impede the efficient interfirm diffusion of new technology. On the other hand Japanese engineers might be expected to have larger intrafirm networks of professional contacts. This should facilitate the intrafirm transfer of technical information. The research reported here tests the applicability of our images of Japanese career practices to engineering careers, replaces the simple dichotomous characterizations of differences between the U.S. and Japan with data suggesting the degrees of difference, and explores linkages between personnel practices and the transfer of information by engineers in both countries.
The standardization of an inventory of child conduct problem behaviors

Abstract This study presents the standardization data for a brief behavioral inventory of child conduct problem behaviors. The 36 item Eyberg Child Behavior Inventory (ECBI) was completed by the parents of 512 children (56% boys) ages 2 to 12. The psychometric characteristics of ECBI indicated that it is a reliable (.86 to .98) and valid instrument whose normally distributed scale is sensitive to a broad range of behavioral variability on the conduct problem dimension. Boys were reported to evidence more conduct problems than girls (p < .001; and mothers consistently reported more problem behaviors than fathers (p < .001). The relative consistency of ECBI scores across ages suggested that a conduct disorder is independent of stages in the child's development. It was suggested that conduct problem behavior is a manifestation of the interaction between the parent and child. The ECBI provides a psycho‐metrically sound parent‐report instrument to be used as an adjunct to observational methods in the treatment...
Identification of Switched Models in Non-Stationary Time Series based on Coordinate-Descent and Genetic Algorithm

Time series analysis is an important research topic in science and engineering. Real-world time series are usually non-stationary with time-varying parameters. Identification of non-stationary time series with a switched model includes finding the switch times and model parameters in each cluster. This problem is a non-convex optimization with equality constraints. Conventional identification methods suffer from restrictive statistical assumptions about the data or switch times, locality of solution, and computational complexity particularly for longer time series. In this paper, a novel coordinate-descent algorithm with the genetic algorithm (GA) and statistical inference is developed. In the evolutionary process, innovative types of crossover and mutation are proposed to improve exploration and exploitation capabilities of the GA, and fitness of the individuals are calculated by the maximum likelihood or least-mean-square.
HIV Type 1 Nef Perturbs Eye Lens Development in Transgenic Mice

ABSTRACT HIV transgenic mice often display lens cataracts as a consequence of viral-specific expression of HIV gene products in the developing lens. Cataractous mouse lines encoding either HIV-1 pr...
Engineering the Brain Tumor Microenvironment Enhances the Efficacy of Dendritic Cell Vaccination: Implications for Clinical Trial Design

Purpose: Glioblastoma multiforme (GBM) is a deadly primary brain tumor. Clinical trials for GBM using dendritic cell (DC) vaccination resulted in antitumor immune responses. Herein, we tested the hypothesis that combining in situ (intratumoral) Ad-Flt3L/Ad-TK–mediated gene therapy with DC vaccination would increase therapeutic efficacy and antitumor immunity. Experimental Design: We first assessed the immunogenicity of tumor lysates generated by Ad-TK (+GCV), temozolomide (TMZ), or freeze/thawing cycles (FTC) in a syngeneic brain tumor model. We also assessed phenotypic markers, cytokine release, and phagocytosis of bone marrow–derived DCs generated by fms-like tyrosine kinase 3 ligand (Flt3L) + IL-6 or by granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin (IL) 4. Inhibition of tumor progression and production of anti-GBM antibodies was assessed following vaccination with (i) tumor cell lysates, (ii) DCs generated with either Flt3L/IL-6 or GM-CSF/IL-4 loaded with either Ad-TK/GCV-, TMZ-, or FTC-generated tumor lysates, or (iii) DCs in combination with in situ Ad-Flt3L/Ad-TK gene therapy. Results: DCs loaded with tumor cell lysates generated with either Ad-TK/GCV or TMZ led to increased levels of phagocytosis, therapeutic efficacy, and humoral immune response. In situ immunogene therapy in combination with DC vaccination led to brain tumor regression and long-term survival in about 90% of animals, a significant increase when compared with either therapy alone. Conclusions: Our results indicate that modifying the tumor microenvironment using intratumoral Ad-Flt3L/Ad-TK–mediated gene therapy potentiates therapeutic efficacy and antitumor immunity induced by DC vaccination. These data support novel phase I clinical trials to assess the safety and efficacy of this combined approach. Clin Cancer Res; 17(14); 4705–18. ©2011 AACR .
Simultaneous pancreas-kidney transplant versus kidney transplant alone in diabetic patients

Simultaneous pancreas-kidney transplant versus kidney transplant alone in diabetic patients. The decision for simultaneous pancreas-kidney (SPK) versus kidney transplant alone (KTA) in diabetic patients with renal failure depends on the potential risks and benefits for each procedure. The purpose of this study was to compare the morbidity, mortality, and renal allograft survival in diabetic patients who underwent SPK versus KTA, and to discern the added risks associated with pancreas transplantation. Between 7/1/86 and 9/30/90, 69 primary cadaver SPK and 59 primary cadaver KTA were performed in type I diabetic patients with chronic renal failure. Antilymphocyte globulin or OKT3 was used for induction therapy, followed by standard triple therapy (prednisone, azathioprine, and cyclosporine). Patient and graft survivals were retrospectively analyzed. In addition, a detailed comparison of morbidity in those patients treated after 7/1/87 was performed (53 SPK, 49 KTA). For those 0.6) in the actuarial patient survival at one year (SPK 92%, KTA 95%), or two years (SPK 89%, KTA 92%), or actuarial renal allograft survival at one year (SPK 82%, KTA 83%) or two years (SPK 77%, KTA 83%). However, for those >45 years old, actuarial renal allograft survival was significantly higher (P 45 are at increased risk and may have poorer renal allograft survival. The increased early morbidity and hospital time should be considered along with the benefits of improved quality of life with a functioning pancreas when offering or selecting patients for SPK transplants.
Far-infrared magnetoreflection studies of graphite intercalated with bromine

An estimate of the hole generation rate in graphite-bromine residue compounds has been made from the interpretation of far-infrared magnetoreflection data. From the cutoff of the (1,2) Landau level transition due to the lowering of the Fermi energy upon bromine intercalation, we estimate that one hole is generated by 55 \ifmmode\pm\else\textpm\fi{} 10 ${\mathrm{Br}}_{2}$ intercalate molecules. This result is shown to be consistent with estimates based on transport measurements. Furthermore, the observed magnetoreflection resonances confirm that for these compounds ($\ensuremath{\lesssim}1$ mole% ${\mathrm{Br}}_{2}$) the electronic structure in the band overlap region is well described by the Slonczewski-Weiss-McClure band model for approximately the same values of the band parameters as for pure graphite.
Nfl gene inactivation in acute myeloid leukemia cells confers cytarabine resistance through MAPK and mTOR pathways.

Nf1 gene inactivation in acute myeloid leukemia cells confers cytarabine resistance through MAPK and mTOR pathways
Evidential reasoning for assessing environmental impact

Abstract Many problems in the areas of environmental monitoring and assessment, site selection and planning, land use management, and natural resources allocation are characterized by the need to consider subjective judgement and uncertain data. Many of these problems are also spatial in nature. This research proposes a formal methodology for integrating subjective inferential reasoning and geographic information systems (GIS) into a decision support system for use in these problem domains. The rationale for inferential spatial models, and the structure and function of a spatial modeling environment based on the Dempster-Shafer theory of evidence are presented.
Rotational equivalence of factor loading matrices with specified values

Under mild assumptions, when appropriate elements of a factor loading matrix are specified to be zero, all orthogonally equivalent matrices differ at most by column sign changes. Here a variety of results are given for the more complex case when the specified values are not necessarily zero. A method is given for constructing reflections to preserve specified rows and columns. When the appropriatek(k − 1)/2 elements have been specified, sufficient conditions are stated for the existence of 2 k orthogonally equivalent matrices.
Immersion freezing of water and aqueous ammonium sulfate droplets initiated by humic-like substances as a function of water activity

Abstract. Immersion freezing of water and aqueous (NH 4 ) 2 SO 4 droplets containing leonardite (LEO) and Pahokee peat (PP) serving as surrogates for humic-like substances (HULIS) has been investigated. Organic aerosol containing HULIS are ubiquitous in the atmosphere; however, their potential for ice cloud formation is uncertain. Immersion freezing has been studied for temperatures as low as 215 K and solution water activity, a w , from 0.85 to 1.0. The freezing temperatures of water and aqueous solution droplets containing LEO and PP are 5–15 K warmer than homogeneous ice nucleation temperatures. Heterogeneous freezing temperatures can be represented by a horizontal shift of the ice melting curve as a function of solution a w by Δ a w = 0.2703 and 0.2466, respectively. Corresponding hetrogeneous ice nucleation rate coefficients, J het , are (9.6 ± 2.5)×10 4 and (5.4 ± 1.4)×10 4 cm −2 s −1 for LEO and PP containing droplets, respectively, and remain constant along freezing curves characterized by Δ a w . Consequently predictions of freezing temperatures and kinetics can be made without knowledge of the solute type when relative humidity and ice nuclei (IN) surface areas are known. The acquired ice nucleation data are applied to evaluate different approaches to fit and reproduce experimentally derived frozen fractions. In addition, we apply a basic formulation of classical nucleation theory (α (T) -model) to calculate contact angles and frozen fractions. Contact angles calculated for each ice nucleus as a function of temperature, α (T) -model, reproduce exactly experimentally derived frozen fractions without involving free-fit parameters. However, assigning the IN a single contact angle for the entire population (single-α model) is not suited to represent the frozen fractions. Application of α-PDF, active sites, and deterministic model approaches to measured frozen fractions yield similar good representations. Furthermore, when using a single parameterization of α-PDF or active sites distribution to fit all individual a w immersion freezing data simultaneously, frozen fraction curves are not reproduced. This implies that these fitting formulations cannot be applied to immersion freezing of aqueous solutions, and suggests that derived fit parameters do not represent independent particle properties. Thus, from fitting frozen fractions only, the underlying ice nucleation mechanism and nature of the ice nucleating sites cannot be inferred. In contrast to using fitted functions obtained to represent experimental conditions only, we suggest to use experimentally derived J het as a function of temperature and a w that can be applied to conditions outside of those probed in laboratory. This is because J het (T) is independent of time and IN surface areas in contrast to the fit parameters obtained by representation of experimentally derived frozen fractions.
Activation by calcium alone of chloride secretion in T84 epithelial cells

1. The goal of this study was to determine if an increase in cytoplasmic calcium concentration ([Ca2+]i), in the absence of additional second messengers derived from membrane phospholipid turnover, is a sufficient signal to induce chloride secretion across monolayers of the human colonic epithelial line, T84. 2. Thapsigargin was used to increase [Ca2+]i by inhibiting the endomembrane Ca(2+)-ATPase. [Ca2+]i was monitored in monolayers by fura-2 fluorescence spectroscopy, chloride secretion by measuring changes in short circuit current (Isc) in modified Ussing chambers, and inositol phosphates were measured by radio-h.p.l.c. of extracts of cells prelabelled with [3H]-inositol. 3. Thapsigargin increased [Ca2+]i and Isc in parallel, without increasing any inositol phosphates. The effect of thapsigargin on Isc was abolished by the intracellular calcium chelator, bis-(o-aminophenoxy)-ethane-N,N,N',N"-tetraacetic acid (BAPTA). 4. Increasing [Ca2+]i with thapsigargin did not prevent a subsequent calcium response to carbachol or histamine if extracellular calcium was available. In the absence of extracellular calcium, only one such release of calcium to hormonal stimulation occurred when cells were pretreated with thapsigargin, and a second response to either carbachol histamine was essentially abolished. 5. Addition of carbachol or histamine to thapsigargin-treated cells mounted in Ussing chambers caused a transient further increase in Isc followed by termination of the response, even though [Ca2+]i continued to rise. 6. We conclude that an elevation in [Ca2+]i is a sufficient signal to induce chloride secretion in T84 cells. Rather than being required to stimulate secretory responses, additional second messengers induced by hormonal secretagogues (such as inositol phosphates) may in fact serve to limit the secretory response.
Time-resolved fourier diffuse optical tomography

A novel approach of time-resolved optical tomography for diffuse optical imaging in a planar geometry provides fast, scalable and three-dimensional image reconstruction with sub-centimeter resolution by a Fourier technique and a picosecond time gated CCD system.
Laser crosshair projection technique for interstory drift measurement

A new method is proposed for measuring interstory drift, the shifting of floors relative to one another when a building undergoes wind or earthquake loading. A laser crosshair is projected from one story to the next, and onto a set of photodetectors which sense changes in the position of the projected light. This paper reports the theory of operation and a quasi-static verification of the method using micropositioning stages to provide input displacements. Lateral positions, including translational and rotational components are calculated from the photodetector outputs, and show excellent agreement with input displacements. The overall performance of the sensor system is extremely linear and predictable, and appears robust enough for field deployment.
Closing the gaps among a web of DNA repair disorders

Summary As recently as six years ago, three human diseases with similar phenotypes were mistakenly believed to be caused by a single genetic defect. The three diseases, Ataxia-telangiectasia, Nijmegen breakage syndrome, and an AT-like disorder are now known, however, to have defects in three separate genes: ATM, NBS1, and MRE11. Furthermore, new recent studies have shown now that all three gene products interact; the ATM kinase phosphorylates NBS1, (1‐4) which, in turn, associates with MRE11 to regulate DNA repair. Remarkably or expectedly, depending on one’s point of view, the similarity in disease phenotypes is evidently due to defects in a common DNA repair pathway. BioEssays 22:966‐969, 2000. fl 2000 John Wiley & Sons, Inc.
Cell-Intrinsic Transforming Growth Factor-β Signaling Mediates Virus-Specific CD8+ T Cell Deletion and Viral Persistence In Vivo

Summary Although deficient CD8 + T cell responses have long been associated with chronic viral infections, the underlying mechanisms are still unclear. Here we report that sustained transforming growth factor-β (TGF-β) expression and phosphorylation of its signaling mediator, Smad-2, were distinctive features of virus-specific CD8 + T cells during chronic versus acute viral infections in vivo. The result was TGF-β-dependent apoptosis of virus-specific CD8 + T cells that related to upregulation of the proapoptotic protein Bim during chronic infection. Moreover, selective attenuation of TGF-β signaling in T cells increased the numbers and multiple functions of antiviral CD8 + T cells and enabled rapid eradication of the persistence-prone virus and memory generation. Finally, we found that cell-intrinsic TGF-β signaling was responsible for virus-specific-CD8 + T cell apoptosis and decreased numbers but was not necessary for their functional exhaustion. Our findings reveal persisting TGF-β-Smad signaling as a hallmark and key regulator of CD8 + T cell responses during chronic viral infections in vivo.
The Charging of Composites in the Space Environment

Deep dielectric charging and subsequent electrostatic discharge in composite materials used on spacecraft have become greater concerns since composite materials are being used more extensively as main structural components. Deep dielectric charging occurs when high energy particles penetrate and deposit themselves in the insulating material of spacecraft components. These deposited particles induce an electric field in the material, which causes the particles to move and thus changes the electric field. The electric field continues to change until a steady state is reached between the incoming particles from the space environment and the particles moving away due to the electric field. An electrostatic discharge occurs when the electric field is greater than the dielectric strength of the composite material. The goal of the current investigation is to investigate deep dielectric charging in composite materials and ascertain what modifications have to be made to the composite properties to alleviate any breakdown issues. A 1-D model was created. The space environment, which is calculated using the Environmental Workbench software, the composite material properties, and the electric field and voltage boundary conditions are input into the model. The output from the model is the charge density, electric field, and voltage distributions as functions of the depth into the material and time. Analysis using the model show that there should be no deep dielectric charging problem with conductive composites such as carbon fiber/epoxy. With insulating materials such as glass fiber/epoxy, Kevlar, and polymers, there is also no concern of deep dielectric charging problems with average day-to-day particle fluxes. However, problems can arise during geomagnetic substorms and solar particle events where particle flux levels increase by several orders of magnitude, and thus increase the electric field in the material by several orders of magnitude. Therefore, the second part of this investigation was an experimental attempt to measure the continuum electrical properties of a carbon fiber/epoxy composite, and to create a composite with tailorable conductivity without affecting its mechanical properties. The measurement of the conductivity and dielectric strength of carbon fiber/epoxy composites showed that these properties are surface layer dominated and difficult to measure. In the second experimental task, the conductivity of a glass fiber/epoxy composite was increased by 3 orders of magnitude, dielectric constant was increased approximately by a factor of 16, with minimal change to the mechanical properties, by adding conductive carbon black to the epoxy.
On using the multiverse to avoid the paradoxes of time travel

To avoid the unpalatable consequences of unidimensional time travel the celebrated paradoxes of preventing one's own birth, etc. it might seem reasonable to appeal instead to the theory of the multiverse.' On that theory, rather than having a time traveller, S, journey into the past of his own universe (call it '(') and thereby court the apparent contradictions, we can instead posit an alternative universe ('P') as his proper destination. The event of S's departing the year 2001 for the year 1001 (say) will therefore be more precisely described as S's leaving his own universe and time, 2001a, and travelling not to 1001a, the ancestor of his own time, but rather to 1001p, i.e., the year 1001 in another universe.2 It follows, say the advocates of the multiverse, that any action S undertakes after travelling to the past occurs in an alternative universe and so cannot affect and, a fortiori, contradict the events of his own. What is intriguing about time travel under the aegis of the multiverse is that it seems, at least prima facie, to allow for the reality of tense; it does not seem to require, in other words, that time be what McTaggart (1908) calls a 'B-series'. The traditional objection against accepting both the possibility of time travel and the reality of tense is well known: if past and future are unreal (as a genuinely tensory series, of course, requires) there will be no time, properly speaking, for the time traveller to travel to, and thus if tense is a genuine part of the world, time travel cannot be. This problem, however, does not arise on the theory of the multiverse as long as we hold the following principle: for every time t, there exists a universe, o, such that the present time in o is t.3 Only a principle such as this could
Neutron scattering in intermetallics

Abstract Inelastic and elastic neutron scattering as a probe of long range and disordered magnetism is discussed for example cases in rare earth intermetallic crystalline compounds and amorphous analogues. The determination of the sublattice site magnetizations is illustrated for RFe2 and Y6(MnxFe1−x)23 compounds. The latter are shown to exhibit strong exchange disorder effects for intermediate compositions, as manifested by the development of short range antiferromagnetic clusters. The effect of randomization of the crystal field interaction in destroying long range order is illustrated in amorphous rare earth compounds and in rare earth compound hydrides. Results of inelastic scattering measurements on Laves phase Fe, Co, and Al compounds are summarized which yield exchange and crystal field parameters.
Pseudoinverse imaging for multimonostatic ground-penetrating radar data

A 2D regularized pseudoinverse algorithm is described for subsurface imaging from multifrequency multi-monostatic ground penetrating radar (GPR) data. The algorithm is based on the Born approximation for vector electromagnetic scattering. Versions of the algorithm using both the ideal point sources/receivers, like the usual inversion algorithms of diffraction tomography (DT), and the arbitrary transmitting/receiving antennas based on Kerns' scattering matrix formulation are given. The algorithm allows either a lossless background medium or an attenuating background. The reconstruction results are obtained analytically by using a regularized pseudoinverse operator. The test results form both synthetic and experimental data are presented to illustrate the use of the algorithm.
Does modern technology belong in gastro-intestinal surgery? A step from subjective perception to objective information

The intra-operative measurement of lower esophageal sphincter (LES) pressure can aid the surgeon in primary repair of the gastroesophageal junction. We evaluated 1,000 patients undergoing primary repairs; 540 patients underwent surgery before the introduction of LES pressure measurements and 460 patients after LES pressure measurement. The incidence of continued reflux was lower in the group having intraoperative LES pressure measurement (4.5% vs. 1.5%). The incidence of continued reflux in this group has been less than 1%. The measurement of intra-operative LES pressure brings objective technology to our patients and improves their quality of life.
The isolation of carcinogenic and other polycyclic aromatic hydrocarbons from barnacles

Summary By chromatographic resolution of certain barnacle extracts (Tetraclita squamosa rubescens) several crystalline fractions, all intensely fluorescent, were obtained containing anthracene, phenanthrene, chrysene, fluoranthene, 1,12-benzperylene, and 3,4-benzpyrene. The latter fraction showed a strong carcinogenic effect in mice. The compounds mentioned do not represent normal metabolic products of the barnacles studied but probably originate from tarry materials floating along the Southern California coast.
A mathematical analysis of human leukocyte antigen serology

Abstract This paper presents and explores a comprehensive mathematical model for human leukocyte antigen serology, based on a mathematical formalization of the concept of specificity. This model is general enough to take into account such factors as absorption, elution, cross-reactivity, and incomplete immunization. The paper includes a presentation of the relevant immunological background and a short discussion of the underlying computational difficulty of the basic problems. Upper and lower bounds are derived for the minimal number of specificities required to explain a given set of HLA reactions, and it is shown that the numbers of antibodies and antigens involved must be no less then this minimal number of specificities. Other techniques and theorems are also presented to aid in reducing and analyzing HLA reaction matrices.
Screening and Mass Spectral Confirmation of β-Lactam Antibiotic Residues in Milk Using LC-MS/MS

Milk is typically screened for beta-lactam antibiotics by nonspecific methods. Although these methods are rapid and sensitive, they are not quantitative and can yield false positive findings. A sensitive and specific method for the quantitation and mass spectral confirmation of five beta-lactam and two cephalosporin antibiotics commonly or potentially used in the dairy industry is described using high-performance liquid chromatography with tandem mass spectrometry. The antibiotics studied were ampicillin, amoxicillin, penicillin G, penicillin V, cloxacillin, cephapirin, and ceftiofur. The antibiotics were extracted from milk with acetonitrile, followed by reversed-phase column cleanup. The extract was analyzed by liquid chromatography coupled with a mass spectrometer, using a water/methanol gradient containing 1% acetic acid on a C-18 reversed-phase column. Determination was by positive ion electrospray ionization and ion trap tandem mass spectrometry. Quantitation was based on the most abundant product ions from fragmentation of the protonated ion for amoxicillin, cephapirin, ampicillin, and ceftiofur and on the fragmentation of the sodium adduct for penicillin G, penicillin V, and cloxacillin. The method was validated at the U.S. FDA tolerance or safe level and at 5 or 2.5 ng/mL for these compounds in bovine milk. Theoretical method detection limits in milk based on a 10:1 signal to noise ratio were 0.2 ng/mL (ampicillin), 0.4 ng/mL (ceftiofur), 0.8 ng/mL (cephapirin), 1 ng/mL (amoxicillin and penicillin G), and 2 ng/mL (cloxacillin and penicillin V) using a nominal sample size of 5 mL.
Growth of neodymium gallium oxide crystals

Abstract The growth of single crystal orthorhombic neodymium gallium oxide is described. Difficulties with twinning, strain and cracks were eliminated by uniform melt temperature and choice of [100] growth direction using an appropriate seed crystal.
Know-how-, Experience- and Competition-related Considerations in Foreign Market Entry: an Exploratory Investigation

Abstract With increasing globalization, the foreign market entry decision has come to acquire increasing strategic significance. This study is based on information drawn directly from managers through in-depth interviews. Drawing from the literature, an investigation was conducted into the manner in which know-how-, experience- and competition-related issues influenced multinational firms' recent foreign market entry decisions, the kinds of concerns managers had regarding their partners and how they dealt with these concerns. The results of the interviews clarify some of confusion in the literature regarding the way in which know-how-related considerations influence market entry preferences and, relatedly, the centrality of opportunism in this decision. They also provide some insight into why prior large-scale statistical studies on foreign market entry have yielded mixed results. Broadly speaking, the results suggest that competitive forces and the capabilities of the firm are increasingly dominant factors influencing firms' entry decisions and driving them towards collaborations. Two interesting findings were the apparent lack of concern with opportunism and the predominant emphasis on the benefits of collaboration rather than the costs. While the efficient exploitation of the know-how may create some pressures towards internalization, its tacit nature also shields the firm from opportunism, thereby mitigating apprehensions about collaborating. In general, the findings of this paper demonstrate the need to re-examine key issues fundamental to foreign market entry and the desirability of shifting the focus of the approach to these issues from cost to value. Basically, the constraints posed by the bounded rationality of economic actors outweigh the constraints posed by opportunistic behavior and, in this light, know-how-related considerations are mediated by competition and capability-related considerations. Accordingly, the paper urges a shift in emphasis from opportunism to capability-related issues and concerns, these being especially critical in today's intensely competitive business environment.
TOPICAL SUBJECT EXPERTISE AND THE SEMANTIC DISTANCE MODEL OF RELEVANCE ASSESSMENT

This paper reports two experiments that investigated the semantic distance model (SDM) of relevance assessment. In the first experiment graduate students of mathematics and economics assessed the relevance relationships between bibliographic records and hierarchies of terms composed of classification headings or help‐menu terms. The relevance assessments of the classification headings, but not the help‐menu terms, exhibited both a semantic distance effect and a semantic direction effect as predicted by the sdm. Topical subject expertise enhanced both these effects. The second experiment investigated whether the poor performance of the help‐menu terms was an experimental design artifact reflecting the comparison of terse help terms with verbose classification headings. In the second experiment the help‐menu terms were compared to a hierarchy of single‐word terms where they exhibited both a semantic distance and semantic direction effect.
On polarimetric SAR speckle filtering

The advancement of SAR technology with high resolution and quad-polarization data demands better and efficient speckle filtering algorithms. In principle, filtering should be applied to distributed media only. Strong pointed targets should be kept unfiltered. In this paper, we will review some of the recently published PolSAR speckle filtering algorithms, and discuss several important issues that affect the speckle filtering results.
Shoulder motion description: The ISB and Globe methods are identical

Abstract Background Three-dimensional shoulder position may be described by rotation sequences such as the proposed ISB standard. Alternative techniques to describe position (the Globe method) seek to simplify this description by eliminating rotation sequences and substituting unambiguous measurements. Methods Both methods (ISB and Globe) were applied to an analysis of shoulder positions, and an overall comparison was performed. Findings The ISB and Globe methods are numerically identical and interchangeable. Interpretation While all analytic methods are mathematically equivalent, investigators have sought simpler and more easily-applied ways of describing shoulder position that would be accurate, easily understood by clinicians, and unambiguous. This study demonstrates that the ISB rotation sequence and Globe descriptive method are numerically the same.
LATITUDINAL GRADIENTS IN THE SPECIES DIVERSITY OF NORTH AMERICAN MAMMALS.

Latitudinal gradients in species-diversity (=numbers of species) are well known. They usually consist of a fairly regular increase in the numbers of species of some higher taxon from the poles to the equator (equatorially-centered gradients, Stehli, 1968). However, latitudinal gradients are known in which maximum diversity does not occur at, or near, the equator (nonequatorially-centered gradients, Stehli, 1968). Various explanations for such gradients have been proposed (see Fischer, 1960; Pianka, 1966; Sanders, 1968, 1969), but none is very satisfactory. A few taxa, such as the fauna of sand beach (Dexter, 1972) and soft-bottom marine (Rosenburg, 1974) habitats, display no latitudinal gradient in species-diversity. Some instances can be attributed to the lack of an accompanying gradient in habitat diversity (Abele, 1974; Dexter, 1972), but others cannot. The analysis of the distribution of North American mammals by Wilson (1974) provides a recent example of the inadequacy of this explanation. Wilson divided the North American continent into 445 quadrats (Fig. 1; as did Simpson, 1964), tabulated the numbers of species of mammals within each quadrat, and plotted these numbers against latitude. Latitudinal trends were determined by fitting a regression line to the resulting cloud of points. Wilson's analysis showed an irregular increase in the numbers of species of quadrupedal mammals (excludes bats) per quadrat from the Arctic region to Panama. The numbers of species per quadrat in the tropics are nearly the same as in the temperate region. He dem-
EFFECT OF THE D178N MUTATION AND THE CODON 129 POLYMORPHISM ON THE METABOLISM OF THE PRION PROTEIN

Prion diseases are thought to be caused by the conversion of the normal, or cellular, prion protein (PrPC) into an abnormal protease-resistant conformation (PrPres). There are three familial forms of human prion disease, Creutzfeldt-Jakob disease (CJD), Gerstmann-Straussler-Scheinker syndrome, and fatal familial insomnia (FFI) which are all expressed at advanced age despite the congenital presence of the mutant prion protein (PrPM). The cellular mechanisms that result in the age-dependent conversion of PrPM into PrPres and the unique phenotypes associated with each PrPM are unknown. FFI and a familial type of Creutzfeldt-Jakob disease (CJD178), share the D178N mutation in the PrP gene but have distinct phenotypes linked to codon 129, the site of a methionine/valine polymorphism (129M/V). We analyzed PrP processing in cells transfected with constructs reproducing the FFI and CJD178 genotypes. The D178N mutation results in instability of the mutant PrP which is partially corrected by N-glycosylation. Hence, only the glycosylated forms of PrPM reach the cell surface whereas the unglycosylated form is degraded. The unglycosylated PrPM is also under-represented in the brain of FFI patients validating the cell model. These results offer new insight into the effect of the D178N mutation on the metabolism of the prion protein.
Improper solutions in the analysis of covariance structures: Their interpretability and a comparison of alternate respecifications

A Monte Carlo approach was employed to investigate the interpretability of improper solutions caused by sampling error in maximum likelihood confirmatory factor analysis. Four models were studied with two sample sizes. Of the overall goodness-of-fit indices provided by the LISREL VI program significant differences between improper and proper solutions were found only for the root mean square residual. As expected, indicators of the factor on which the negative uniqueness estimate occurred had biased loadings, and the correlations of its factor with other factors were also biased. In contrast, the loadings of indicators on other factors and those factor intercorrelations did not have any bias of practical significance. For initial solutions with one negative uniqueness estimate, three respecifications were studied: Fix the uniqueness at .00, fix it at .20, or constrain the domain of the solution to be proper. For alternate, respecified solutions that were converged and proper, the constrained solutions and uniqueness fixed at .00 solutions were equivalent. The mean goodness-of-fit and pattern coefficient values for the original improper solutions were not meaningfully different from those obtained under the constrained and uniqueness fixed at .00 respecifications.
Optimal Adaptive Data Transmission over a Fading Channel with Deadline and Power Constraints

We consider optimal rate control for energy-efficient data transmission over time-varying (fading) channels with strict deadline constraints. Specifically, the scenario consists of a transmitter with B units of data that must be transmitted by deadline T over a wireless channel. The transmitter can control the transmission rate over time by varying the transmission power subject to expected short-term power limits. The expended power depends on both the (chosen) transmission rate and the present channel condition and the objective is to adapt the rate over time and in response to the changing channel conditions so that the total energy cost is minimized. We present a novel continuous-time formulation of the problem; using stochastic control theory and lagrangian duality, we obtain explicitly the optimal rate control policy. We then present an illustrative simulation example comparing the energy costs of the optimal and the full power policies.
Genes, Eyeglasses, and Social Policy

Someone reading empirical research relating human genetics to personal outcomes must be careful to distinguish two types of work: An old literature on heritability attempts to decompose cross-sectional variation in observed outcomes into unobservable genetic and environmental components. A new literature measures specific genes and uses them as observed covariates when predicting outcomes. I will discuss these two types of work in terms of how they may inform social policy. I will argue that research on heritability is fundamentally uninformative for policy analysis, but make a cautious argument that research using genes as covariates is potentially informative.
Activation volumes associated with chromophore reorientation in corona poled guest–host and side‐chain polymers

The decay of the second-order optical susceptibility χ(2) as a function of temperature and pressure has been studied in a variety of corona poled guest–host and side-chain polymeric materials using second harmonic generation (SHG). The specific systems studied include the side-chain copolymer poly(disperse red 1 methacrylate-co-methyl methacrylate) (DR1-MMA) as well as the series of guest–host materials formed by individually dissolving the dyes Disperse Red 1 (DR1), Disperse Orange 3 (DO3), and N,N dimethyl-p-nitroaniline (DpNA) in poly(methyl methacrylate) (PMMA), polycarbonate (PC), and polystyrene (PS). In each of these systems, the observed relaxation of χ(2) can be represented by a Kohlrausch-Williams-Watts stretched exponential, from which the decay time τ and decay distribution width β are determined. For pressures up to approximately 1000 atm, the natural log of the pressure shift factor is seen to vary linearly with applied pressure, yielding the activation volume for rotational reorientation of the chromophores in each system. The activation volumes are loosely correlated with dopant size in a given polymer host, but are not the same for a given dopant in different hosts. Modeling the chromophores as rotating cylinders, we show that the measured activation volumes do not correspond to the average volume swept out by the dye molecules as they reorient. On the other hand, the activation volumes for each of the three dyes dissolved in PS are seen to be in agreement with the measured activation volumes for the molecular motions associated with volume recovery in neat PS. Moreover, the activation volumes for DR1 and DpNA dissolved in PS are seen to correlate with the proposed couplings between the rotational reorientation of DR1 and the α-relaxation dynamics of PS and the slight decoupling of DpNA from the α-transition motion of PS. This correlation suggests a possible relationship between the activation volumes for chromophore reorientation and the size of the components of the host polymer or the volume swept through by the polymer components during structural reconfiguration. We demonstrate that assuming activation volumes for chromophore reorientation to be related to the size or motion of the polymer host constituents yields a consistent interpretation of the observed trends in the measured activation volumes. © 1995 John Wiley & Sons, Inc.
Production and Diagnosis of a Highly Spin-Polarized Na Beam

We describe optically pumping a beam of sodium atoms to >96% mS and >92% mS, mI state selection. (We have accurately measured the population of every mS, mI state in the optically pumped beam.) For the optical pumping both ground hyperfine states are pumped, using single-mode cw dye-laser radiation tuned to the 3S1/2–3P1/2 transition that is phase modulated in a LiTaO3 crystal to produce first-order sidebands at approximately the 1772-MHz hyperfine splitting of the ground state. The z-directed optical pumping is performed in a z-directed magnetic field of ~5 G. The state-selected atoms then move, in ~1 cm, into an ~200 G, z-directed field. The downstream probe laser beam is scanned through the 3S1/2 (mS, mI) → 3P3/2 (mS′, mI) transitions, which are spectroscopically resolved at 200 G, and the fluorescence intensities portray the residual populations in each of the eight 3S1/2 states.
Using haptic vector fields for animation motion control

We are developing paradigms and algorithms for browsing and editing families of animation using a haptic force-feedback device called a Phantom. These techniques may be generalized to navigation of any high degree-of-freedom system from a lower degree-of-freedom control space, with applications to telerobotics and simulation of virtual humans. We believe that modeling the animation configuration space coupled with the highly interactive nature of the haptic device provides one with useful and intuitive means of control. We have implemented our ideas in a system for the manipulation of animation motion capture data; in particular, anthropomorphic figures with 57 degrees of freedom are controlled by the user in real time. We treat trajectories, which encode animation, as first-class objects; haptic manipulation of these trajectories results in change to the animation. We have several haptic editing modes in which these trajectories are either haptically deformed or performed by the user with expressive control subject to dynamic haptic constraints.
Pulmonary Function in Former Alcoholics

Pulmonary function was evaluated in 44 former alcoholics (abstinence, 0.5 to 32 years) without cardiac or specific pulmonary disease. All were members of Alcoholics Anonymous. Fourteen subjects (32 percent) were nonsmokers, ex-smokers, and cigar or pipe smokers, yet 28 subjects (64 percent) had abnormal expiratory flow rates, and 17 (39 percent) had an elevated value for the ratio of the residual volume to the total lung capacity. Single-breath diffusing capacity was abnormal in seven subjects (16 percent). Of interest was the high incidence (77 percent) of obstructive phenomena among the women. This high incidence of abnormalities among both the men and women could not be attributed to previous pulmonary infection or smoking. Comparison of these patients with chronic alcoholics suggests that the obstructive component in these patients is, in part, a result of their past alcoholic intake and that it is not reversed by abstinence. On the other hand, the impairment in diffusion, which was so common in alcoholics, appears to be reversible with sobriety.