cssi/SciSciGPT-SciSciNet huggingface dataset:
The relation of Algols and W Serpentis stars

Evidence on the issues of whether the W Serpentis stars are a coherent class, and how they may interface with the Algol systems, is reviewed, with emphasis on the idea that they are semi-detached systems in the latter part of the rapid phase of mass transfer, with optically and geometrically thick disks of transferred gas around the (now) more massive star. We are interested in what will be seen when the gas clears away, and mainly examine the idea that it will be an Algol-type system. More particularly, consideration is given to centrifugally limited accretion as a mechanism to build up a substantial disk, and the presumed evolutionary sequence is from a W Ser to a rapidly rotating Algol to a normal Algol system. Systems such as V367 Cyg and RW Tau fit into this scheme only with difficulty. Because it is extremely difficult to measure the rotation of some W Ser (mass) primaries, it is natural to look at the rotation statistics of Algols to test this idea. The badly behaved light curves and spectroscopy of some Algols (eg. U Cep, RZ Sct) may be attributable to the double contact condition, and the ramifications of this possibility are discussed. If so, the rotation statistics of Algols should show two spikes, corresponding to the two special conditions into which a system should be driven by tidal braking and centrifugally limited spinup. Present rotation statistics do show these spikes. Algols should flip between these states fairly quickly, depending on the mass transfer rate. Thus, to the extent that the meager statistics can be accepted as meaningful, the new (fourth) morphological type of close binary (double contact) has attained demonstrable reality. The rotation statistics are presented in terms of a particular rotation parameter, R, which is zero for synchronism and unity for the centrifugal limit. Future work should develop rotation statistics to see if the rotational lobe-filling (R = 1) spike persists. It should also look into whether W Ser primaries are on the hydrogen burning main sequence, or in general what they are. We also need more light curves of W Ser type systems, high resolution line profiles for the (mass) primaries (with particular attention to the W Ser-Algol transition cases), and spectroscopy of low inclination W Serpentis systems, such as KX And.
The Efficacy of Registration Drives

A great deal of money and effort is devoted to registration drives. New sources of data now make it possible to discover more about who is registered by groups and how many of the new registrants actually vote. Using 1982 registration information from the Los Angeles County Registrar, this note presents some basic descriptive findings that pertain to these questions.
An Online Approach to Dynamic Channel Access and Transmission Scheduling

Making judicious channel access and transmission scheduling decisions is essential for improving performance (delay, throughput, etc.) as well as energy and spectral efficiency in multichannel wireless systems. This problem has been a subject of extensive study in the past decade, and the resulting dynamic and opportunistic channel access schemes can bring potentially significant improvement over traditional schemes. However, a common and severe limitation of these dynamic schemes is that they almost always require some form of a priori knowledge of the channel statistics. A natural remedy is a learning framework, which has also been extensively studied in the same context, but a typical learning algorithm in this literature seeks only the best static policy (i.e., to stay in the best channel), with performance measured by weak regret, rather than learning a good dynamic channel access policy. There is thus a clear disconnect between what an optimal channel access policy can achieve with known channel statistics that actively exploits temporal, spatial and spectral diversity, and what a typical existing learning algorithm aims for, which is the static use of a single channel devoid of diversity gain. In this paper we bridge this gap by designing learning algorithms that track known optimal or sub-optimal dynamic channel access and transmission scheduling policies, thereby yielding performance measured by a form of strong regret, the accumulated difference between the reward returned by an optimal solution when a priori information is available and that by our online algorithm. We do so in the context of two specific algorithms that appeared in [1] and [2], respectively, the former for a multiuser single-channel setting and the latter for a single-user multichannel setting. In both cases we show that our algorithms achieve sub-linear regret uniform in time and outperforms the standard weak-regret learning algorithms.
Assessment of 4H-SiC epitaxial layers and high resistivity bulk crystals for radiation detectors

We present results of structural, electrical, and defect characterization of 4H-SiC epitaxial layers and bulk crystals and show performance of the radiation detectors fabricated from these materials. The crystal quality was evaluated by x-ray diffraction (XRD) rocking curve measurements, electron beam induced current (EBIC) imaging, and defect delineating etching in conjunction with optical microscopy and scanning electron microscopy (SEM). Studies of the electrically active intrinsic defects and impurities were conducted using thermally stimulated current (TSC) measurements in a wide temperature range of 94 - 750K. The results are correlated with the capability of bulk crystals and epitaxial layers for the detection of α-particles, low to high energy x-rays and gamma rays. High barrier rectifying Schottky diodes have been fabricated and tested. The epitaxial 4H-SiC radiation detectors exhibited low leakage current (< 1 nA) at ~ 200 V operating voltage up to 200 C. The soft x-ray responsivity measurements performed at the National Synchrotron Light Source (NSLS) at Brookhaven National Lab (BNL) showed significantly improved characteristics compared to commercially-available SiC UV photodiode detectors.
Empowering young inventors: an experimental course on IP and patent application drafting at Auburn University

A new one-credit course on IP and patent application drafting was offered at Auburn University jointly by the authors in spring 2009. The course started with a target of 15 students. Within 1 week of its announcement, the course was oversubscribed; the class was filled within a week of its announcement through e-mails to engineering and business students, a few were turned down, 16 were enrolled including one MS and one Ph.D. student from engineering (graduate students were required to do an additional term paper). The goal of this first-of-its-kind course at Auburn was to teach undergraduate and graduate students to understand the protection of intellectual property rights, and to train them to prepare a patent application fit for submission to the US Patent and Trademark Office (USPTO). The hands-on experience was intended to give them the freedom to grab their own new ideas and protect them through patents as a first step towards the commercial exploitation of their intellectual property (IP). The paper explains the limited goals of the course, outcome and conclusions with a recommendation for other universities to offer a similar course. The course fulfilled an important need and empowered some of the young inventors in the class to consider venturing into a new business based on their product ideas.
Black hole evolution

Black hole formation and evaporation is studied in the semiclassical approximation in simple 1+1-dimensional models, with emphasis on issues related to Hawking's information paradox. Exact semiclassical solutions are described and questions of boundary conditions and vacuum stability are discussed. The validity of the semiclassical approximation has been called into question in the context of the information puzzle. A different approach, where black hole evolution is assumed to be unitary, is described. It requires unusual causal properties and kinematic behavior of matter that may be realized in string theory.
A PECULIAR EMISSION-LINE FEATURE IN THE X-RAY SPECTRUM OF THE QUASAR PKS 0637 752

We report the results from an ASCA observation of the high-luminosity, radio-loud quasar PKS 0637-752 (redshift 0.654), covering the 0.8-15 keV band in the quasar frame. We find the source to have a luminosity of ~1046 ergs s-1 in the 2-10 keV band, which is a factor of ~3 lower than during a previous Ginga observation. The continuum appears to be well modeled by a simple power law with Γ=1.64±0.07, with no evidence for absorption by material intrinsic to the quasar or Fe-K emission (with an equivalent width 80 eV at 90% confidence). However, we do find evidence for a narrow emission line at an energy 1.60±0.07 keV and equivalent width 59+ 38−34 eV (both in the quasar frame). Line emission at these energies has not been observed in any other active galaxy or quasar to date. We reject the possibility that this line is the result of instrumental artifacts and briefly explore possible identifications.
Cranial muscle markers: a preliminary examination of size, sex, and age effects.

Abstract Most muscle marker research consists of post-cranial analyses, but some researchers examine crania to reconstruct activities. Regardless of bones examined, anthropologists know of some of the complexities surrounding muscle marker development. Here, posterior cranial muscle markers are analyzed to determine whether they are useful in reconstructing activities by examining effects that may hinder reconstructions. Additionally, upper limb muscle markers and humeral cross-sectional robusticity variables are correlated with cranial muscle markers to determine if robust individuals are generally robust due to the synergistic effects of muscle use. Cranial muscle markers of 65 prehistoric California Amerinds are scored using a five-point observer rating scale. Body mass is calculated from femoral head size; maximum cranial length and breadth are measured with a spreading caliper; and age and sex are determined through standard procedures. Upper limb muscle markers are scored on seven sites using two dimensions within a seven-point scale. Cross-sectional properties are calculated from biplanar humeral radiographs. Aggregates are created for cranial muscle markers, upper limb muscle markers, and cross-sectional robusticity. Cranial muscle markers correlate significantly with cranial length, r=0.25 and cross-sectional robusticity of humerus, r=0.29; P’s
Reactions of laser-ablated uranium atoms with H2O in excess argon: a matrix infrared and relativistic DFT investigation of uranium oxyhydrides.

Laser-ablated U atoms react with H2O during condensation in excess argon. Infrared absorptions at 1416.3, 1377.1, and 859.4 cm-1 are assigned to symmetric HUH, antisymmetric HUH, and UO stretching vibrations of the primary reaction product H2UO. Uranium monoxide, UO, also formed in the reaction, inserts into H2O to produce HUO(OH), which absorbs at 1370.5, 834.3, and 575.7 cm-1. The HUO(OH) uranium(IV) product undergoes ultraviolet photoisomerization to a more stable H2UO2 uranium(VI) molecule, which absorbs at 1406.4 and 885.9 cm-1. Several of these species, particularly H2UO2, appear to form weak Ar-coordinated complexes. The predicted vibrational frequencies, relative absorption intensities, and isotopic shifts from relativistic DFT calculations are in good agreement with observed spectra, which further supports the identification of novel uranium oxyhydrides from matrix infrared spectra.
Hierarchical Negotiation Model for Complex Problems with Large-Number of Interdependent Issues

Negotiation is usually dealt with package deals, where all issues are considered together. We propose a hierarchical negotiation approach where various sets of issues are negotiated at different levels. As the number of interdependent issues in negotiation grows, it becomes computationally intractable to generate proposals on all issues and to evaluate such proposals. By modeling all issues in negotiation as a hierarchical structure, it significantly reduces the search space in each negotiation session and improves the probability of finding better negotiation outcomes. Since a numeric utility function for multiple interdependent issues is hard to acquire in most real-world applications, a constraint-based preference representation is adopted in this approach to mimic the preference model used by human. This paper presents the design of this hierarchical negotiation model, and illustrates how it works using an example of vehicle design process. Experimental results are presented to evaluate the the performance and efficiency of this approach.
A Deliberative Model of Corporate Medical Management

The author examines the issue of interprofessional and intraprofessional conflict in the context of disease management systems. Using political theory and business ethics, the author develops a model of organizational ethics and applies it to disease management programs and other potential sites where business and clinical ethics clash.
Update on Light WIMP Limits: LUX, lite and Light

We reexamine the current direct dark matter data including the recent CDMSlite and LUX data, assuming that the dark matter consists of light WIMPs, with mass close to 10 GeV/c2 with spin-independent and isospin-conserving or isospin-violating interactions. We compare the data with a standard model for the dark halo of our galaxy and also in a halo-independent manner. In our standard-halo analysis, we find that for isospin-conserving couplings, CDMSlite and LUX together exclude the DAMA, CoGeNT, CDMS-II-Si, and CRESST-II possible WIMP signal regions. For isospin-violating couplings instead, we find that a substantial portion of the CDMS-II-Si region is compatible with all exclusion limits. In our halo-independent analysis, we find that for isospin-conserving couplings, the situation is of strong tension between the positive and negative results, as it was before the LUX and CDMSlite bounds, which turn out to exclude the same possible WIMP signals as previous limits. For isospin-violating couplings, we find that LUX and CDMS-II-Si bounds together exclude or severely constrain the DAMA, CoGeNT and CRESST-II possible WIMP signals.
Photoacoustic tomography of foreign bodies in soft biological tissue

In detecting small foreign bodies in soft biological tissue, ultrasound imaging suffers from poor sensitivity (52.6%) and specificity (47.2%). Hence, alternative imaging methods are needed. Photoacoustic (PA) imaging takes advantage of strong optical absorption contrast and high ultrasonic resolution. A PA imaging system is employed to detect foreign bodies in biological tissues. To achieve deep penetration, we use near-infrared light ranging from 750 to 800 nm and a 5-MHz spherically focused ultrasonic transducer. PA images were obtained from various targets including glass, wood, cloth, plastic, and metal embedded more than 1 cm deep in chicken tissue. The locations and sizes of the targets from the PA images agreed well with those of the actual samples. Spectroscopic PA imaging was also performed on the objects. These results suggest that PA imaging can potentially be a useful intraoperative imaging tool to identify foreign bodies.
Determination of molecular-ion structures through studies of the collisionally-induced dissociation of fast (MeV) molecular ions

Abstract High-resolution studies of the angle and energy distributions of fragments detected in coincidence from the foil- and gas- induced dissociation of fast (MeV) polyatomic molecular ions are described. The aim of the measurements is to explore the possibilities that these new techniques offer for determining the stereochemistry of molecular ions.
Log-ratio technique for beam position monitor systems

Abstract Recent progress in the development of a beam position monitor system (BPM), based on the log-ratio technique, is described in this paper. A complete electronic analysis is presented, showing linearity, dynamic range, noise, RF burst response, and temperature dependence. A calibration technique has been developed, which corrects the errors due to mismatched channels and electronics drift. This technique is particularly effective because of the log-ratio property for beam position monitoring.
Experimental investigation of the thermal contact conductance of electroplated silver coatings

Standard electronic modules can be made more reliable by decreasing module temperature. This may be accomplished by increasing the thermal contact conductance of the junction between the frame guide ribs and chassis card rails. Soft metallic coatings for the card rails would deform readily under pressure, thereby increasing the actual contact area and associated conductance. This investigation evaluated the conductance enhancement provided by vapor deposited, electroplated, and flame-sprayed silver coatings. Experimental measurements of thermal contact conductance were performed for anodized aluminum 6101-T6 and electroless nickel-plated copper C11000-H03 frame materials injunction with uncoated and silver-coated A356-T61 card rail material. Baseline conductance data for the anodized aluminum 6101 to uncoated aluminum A356 varied from 25 to 91 W/m 2K (4.4 to 16 Btu/h ft20F), and values for the nickel-plated copper to uncoated aluminum A356 ranged from 600 to 2800 W/m2K (106 to 493 Btu/h ft2°F) for contact pressures of 172-862 Kpa (25 to 125 psi) and mean junction temperatures of 20-100°C (68-212°F). Experimental conductance data for vapordeposited, electroplated, and flame-sprayed silver-coated aluminum A356 demonstrated thermal enhancement factors of 1.44-2.14, 1.78-15.2, and 1.00-2.30, respectively, for junctions with anodized aluminum 6101, and 0.76-2.19, 1.06-2.83, and 0.45-0.75, respectively, for junctions with nickel-plated copper. The vapor deposited and thinner flame-sprayed coatings were susceptible to galvanic corrosion. All electroplated and the thicker flame-sprayed coatings exhibited excellent corrosion resistance.
State Space Modeling of an Acoustic Duct With an End-Mounted Speaker

This paper develops a state space model of the dynamics of an acoustic duct with end-mounted speakers. The initial model formulation includes the forcing term as part of the boundary conditions. The shifted particle velocity is then defined to transform the nonhomogeneous boundary conditions into homogeneous boundary conditions and thus develop the state space model. It is shown that the speaker and acoustic dynamics interact by means of feedback in which the speaker creates an acoustic field, which, in turn, affects the motion of the speaker cone. This interaction is studied using positive real closed-loop feedback analysis, and shifts in the modal frequencies of the duct due to the presence of the end-mounted speaker are predicted.
Baryon masses at second order in chiral perturbation theory

Abstract We analyze the octet baryon mass differences up to second order in chiral perturbation theory, including the effects of decupletintermediate states. We show that the Coleman-Glashow relation has computable corrections of order ( m m − m u ) m s . Thesecorrections are numerically small, and in agreement with the data. We also show that corrections to the Σ equal-spacing rule aredominated by electromagnetic contributions, and that the Gell-Mann-Okubo formula has non-analytic corrections of order m s 2 In m s which cannot be computed from known matrix elements. We also show that the baryon masses cannot be used to extractmodel-independent information about the current quark masses.
Parallel connections and bundles of arrangements

Abstract Let A be a complex hyperplane arrangement, and let X be a modular element of arbitrary rank in the intersection lattice of A . Projection along X restricts to a fiber bundle projection of the complement of A to the complement of the localization A X of A at X. We identify the fiber as the decone of a realization of the complete principal truncation of the underlying matroid of A along the flat corresponding to X. We then generalize to this setting several properties of strictly linear fibrations, the case in which X has corank one, including the triviality of the monodromy action on the cohomology of the fiber. This gives a topological realization of results of Stanley, Brylawsky, and Terao on modular factorization. We also show that (generalized) parallel connection of matroids corresponds to pullback of fiber bundles, clarifying the notion that all examples of diffeomorphisms of complements of inequivalent arrangements result from the triviality of the restriction of the Hopf bundle to the complement of a hyperplane. The modular fibration theorem also yields a new method for identifying K(π,1) arrangements of rank greater than three. We exhibit new families of K(π,1) arrangements, providing more evidence for the conjecture that factored arrangements of arbitrary rank are K(π,1).
Barriers to Resolution in Ideologically Based Negotiations: The Role of Values and Institutions

Although traditional behavioral decision theory as applied to negotiation sheds light on some of the barriers encountered in negotiations, it does not fully account for many of the difficulties and failures to reach settlement in ideologically based disputes. In this article we identify a number of factors that differentiate ideologically based negotiations from other types of negotiations and advance a perspective that takes into account the value-laden and institutional contexts in which they occur. We illustrate our ideas by applying them to the organizationally relevant example of environmental disputes.
Per capita income growth, social expenditures and living standards:Evidence from rural India

Abstract Using pooled time series data across 15 major states of India, the relationships between measures of living standards and per capita income and government expenditures in social sectors are estimated. Female literacy, infant mortality, total fertility rates and level of poverty are taken as measures of living standards. Public expenditures on education, and improvement of medical facilities are found to be more effective in improving living standards than growth in income alone. In particular, the state of Kerala is not an outlier in its achievement of impressively higher living standards, relative to other states, after controlling for government expenditures in the social sectors. These conclusions do not change after controlling for fixed effects and with application of robust estimation procedures. ( JEL 015, H51, H52)
Reducing Composition Errors: An Experiment

and over again, despite the fact that they have studied certain rules of grammar.1 Fortunately or unfortunately, the problem of recurring errors is not peculiar to the teaching of German. The question remains, therefore, what measures teacher and student can take to ameliorate the situation. How can students be brought to show an appreciable decline in errors from one essay to the next, or at least from course beginning to course end? Numerous suggestions have been advanced by foreign language methodologists, educational psychologists, and applied linguists as to how writing skills might best be developed. While many seem worthy of implementation, few offer data to support their claims of efficacy. For example, in Cooper's excellent article on the effects of sentence-combining techniques, he admits that no data were available to indicate whether positive correlations existed between the successful "hastened development of syntactic maturity" and grammatical accuracy (i.e., correctness of expression, excluding lexical errors).2 What suggestions have professionals in the field advanced to develop writing skills so that student errors decrease as their writing skill matures? A perusal of the professional literature leads to the conclusion that the following represent components of an effective strategy for the development of writing skills-at least for most modern foreign languages taught in this country. Comprehensive Error Correction. While selective correction of errors is certainly defensible in the development of speaking skills, the same cannot be said where writing skills are concerned. Unless all errors are identified, the faulty linguistic structures, rather than the correct ones, may become ingrained in the student's interlanguage system. Thompson's pragmatic position on error correction is difficult to rebut: "The student does not improve his skill if his work is not corrected."3
The Velocity Anisotropy of Distant Milky Way Halo Stars from Hubble Space Telescope Proper Motions

Based on long baseline (5-7 years) multi-epoch HST/ACS photometry, used previously to measure the proper motion of M31, we present the proper motions (PMs) of 13 main-sequence Milky Way halo stars. The sample lies at an average distance of r 24 kpc from the Galactic center, with a root-mean-square spread of 6 kpc. At this distance, the median PM accuracy is 5 km s–1. We devise a maximum likelihood routine to determine the tangential velocity ellipsoid of the stellar halo. The velocity second moments in the directions of the Galactic (l, b) system are km s–1, and km s–1. We combine these results with the known line-of-sight second moment, km s–1, at this r to study the velocity anisotropy of the halo. We find approximate isotropy between the radial and tangential velocity distributions, with anisotropy parameter . Our results suggest that the stellar halo velocity anisotropy out to r ~ 30 kpc is less radially biased than solar neighborhood measurements. This is opposite to what is expected from violent relaxation, and may indicate the presence of a shell-type structure at r ~ 24 kpc. With additional multi-epoch HST data, the method presented here has the ability to measure the transverse kinematics of the halo for more stars, and to larger distances. This can yield new improved constraints on the stellar halo formation mechanism, and the mass of the Milky Way.
Dawn simulation treatment of abstinent alcoholics with winter depression

Background: Recent data suggest that winter depression (seasonal affective disorder [SAD]) may be a subtype of affective disorder that is closely related to alcoholism. Dawn simulation has been shown in controlled trials to be effective in SAD. The present study examined the effectiveness of dawn simulation in abstinent alcoholics who met DSM-III-R criteria for major depression, or bipolar disorder, depressed with seasonal pattern. Method: All 12 subjects with winter depression had a history of either alcohol dependence or alcohol abuse according to DSM-III-R and had been abstinent from alcohol for at least 6 months. They also fulfilled criteria for SAD according to Rosenthal and were hypersomnic and drug free. After a 1-week baseline period, the subjects were randomly assigned to a 1-week treatment period at home with either a white 1.5-hour dawn from 4:30 a.m. to 6:00 a.m. peaking at 250 lux or a red 1.5-hour dawn from 4:30 a.m. to 6:00 a.m. peaking at 2 lux. The subjects were told that they would receive daily either a red or a white dawn reaching the same illuminance, an illuminance that would be much dimmer than standard bright light treatment. At the end of each week, the subjects were blindly assessed by a psychiatrist using the Structured Interview Guide for the Hamilton Depression Rating Scale-Seasonal Affective Disorder version (SIGH-SAD). Results: For the 6 subjects completing the white dawn treatment, the mean SIGH-SAD score decreased from 33.0 at baseline to 15.8 after treatment. For the 6 subjects completing the dim red dawn treatment, the mean SIGH-SAD score decreased from 34.3 to 32.7. The mean post-dawn SIGH-SAD score was significantly lower after the white dawn treatment than after the dim red dawn treatment (ANCOVA with baseline SIGH-SAD as the covariate, F = 12.95, p <.01). Superiority of the white dawn was also found by analogous analyses for the Hamilton Rating Scale for Depression (HAM-D) (p <.01) and the SAD Subscale (p <.05). Conclusion: The present study suggests that dawn simulation may be helpful in decreasing depression in abstinent alcoholics with SAD. Further study is necessary to confirm these preliminary findings and to determine whether dawn simulation might be helpful in preventing relapse in abstinent alcoholics who have SAD.
Pluto’s implications for a Snowball Titan

The current Cassini–Huygens Mission to the Saturn system provides compelling evidence that the present state of Titan’s dense atmosphere is unsustainable over the age of the Solar System. Instead, for most of its existence, Titan’s atmosphere might have been in a Snowball state, characterized by a colder surface and a smaller amount of atmospheric CH_4, similar to that of Pluto or Triton. We run a 1-D chemical transport model and show that the rates of organic synthesis on a Snowball Titan are significantly slower than those on present-day Titan. The primary method of methane destruction—photosensitized dissociation in the stratosphere—is greatly dampened on Snowball Titan. The downward flux of higher-order molecules through the troposphere is dominated not by hydrocarbons such as ethane, as is the case on Titan today, but by nitriles. This result presents a testable observation that could confirm the Snowball Titan hypothesis. Because Pluto’s atmosphere is similar to Titan’s in composition, it serves as a basis for comparison. Future observations of Pluto by the New Horizons Mission will inform photochemical models of Pluto’s atmosphere and can help us understand the photochemical nature of paleo-Titan’s atmosphere.
Filters for soft x-ray solar telescopes

Soft X-ray telescopes require filters that block visible and infrared light and have good soft X-ray transmission. The optical properties of possible materials are discussed, and the fabrication and testing methods for the filters used in a 10-inch normal incidence telescope for 63 A are described. The best performances in the 44-114-A wavelength range are obtained with foils of carbon and rhodium.
Endoscopic Repair of Orbital Floor Fractures

Significant orbital trauma can result in orbital floor fractures with subsequent prolapse of the orbital contents into the paranasal sinuses. Prolapse of the periorbita can result in extraocular muscle entrapment, diplopia, enophthalmos, and even visual loss. Management of orbital floor fractures traditionally has been accomplished through transconjunctival and subciliary incisions. These approaches provide adequate visualization and cosmetically acceptable scars. Unfortunately, post-operative lid malposition can occur in a small percentage of cases. Another limitation is easy visibility of the posterior orbit, which often is obscured by prolapsed orbital fat. In light of these limitations, some surgeons have begun to evaluate an endoscopic approach to orbital floor fractures. The endoscopic approach offers a hidden incision, improved fracture visualization, and avoidance of post-operative eyelid malposition. This article reviews the indications, technique, and potential complications of endoscopic orbital blow-out fracture repair.
A design study for the basic TEM horn antenna

In this paper, a design study was performed for the basic TEM horn antenna. In the theoretical model, care was taken to avoid the problems associated with the use of gap sources when calculating the reflection coefficient and input impedance of the antenna. All numerical calculations were made with a program based on the method of moments, and the accuracy of the numerical calculations was established with measured results for selected antennas. The transverse electromagnetic (TEM) horn antenna is a popular broadband antenna. The basic antenna has a simple design consisting of two triangular plates and a feeding structure. The horn is described completely by only three variables: /spl alpha/, /spl beta/, and s. /spl alpha/ is the angular width of each plate, /spl beta/ is the angular separation between the two plates, and s is the length, measured from the drive point to the corner of the plate. The geometry of the basic TEM horn antenna does not require a particular choice of a feeding method.
Capacity Limits of Multiuser Multiantenna Cognitive Networks

Unlike point-to-point cognitive radio, where the constraint imposed by the primary rigidly curbs the secondary throughput, multiple secondary users have the potential to efficiently harvest the spectrum and share it among themselves. This paper analyzes the sum throughput of a multiuser cognitive radio system with multiantenna base stations, either in the uplink or downlink mode. The primary and secondary have N and n users, respectively, and their base stations have M and m antennas, respectively. We show that an uplink secondary throughput grows with m/N+1 log n if the primary is a downlink system, and grows with m/M+1 log n if the primary is an uplink system. These growth rates are shown to be optimal and can be obtained with a simple threshold-based user selection rule. In addition, we show that the secondary throughput can grow proportional to , while simultaneously the interference on the primary is forced down to zero, asymptotically. For a downlink secondary, it is shown that the throughput grows with in the presence of either an uplink or downlink primary system. In addition, the interference on the primary can be made to go to zero asymptotically, while the secondary throughput increases proportionally to . The effect of unequal path loss and shadowing is also studied. It is shown that under a broad class of path loss and shadowing models, the secondary throughput growth rates remain unaffected.
‘Too Little’ or ‘Too Late’: The timing of supply chain demand collaboration

Abstract This study examines the supply chain demand collaboration between a manufacturer and a retailer. We study how the timing of collaboration facilitates production decision of the manufacturer when the information exchanged in the collaboration is asymmetric. We investigate two collaboration mechanisms: ‘Too Little’ and ‘Too Late’, depending on the timing of information sharing between the manufacturer and the retailer. Our research results indicate that early collaboration as in the ‘Too Little’ mechanism leads to a stable production schedule, which decreases the need of production adjustment when production cost information becomes available; whereas a late collaboration as in the ‘Too Late’ mechanism enhances the flexibility of production adjustment when demand information warrants it. In addition, the asymmetric demand information confounds production decisions all the time; the manufacturer has to provide proper incentives to ensure truthful information sharing in collaboration. Information asymmetry might also reduce the difference in production decision between the ‘Too Little’ and ‘Too Late’ collaboration mechanisms. Numerical analysis is further conducted to demonstrate the performance implications of the collaboration mechanisms on the supply chain.
Why, what and how of teaching power electronics

Engineering employers are demanding that engineering graduates must have certain skills. Each engineering curriculum must provide certain skills and abilities, and fulfill its educational program objectives within the mission and goals of the institution. Each engineering program must also demonstrate that the graduates have achieved certain outcomes.
Falling antimatter: An experiment to measure the gravitational acceleration of the antiproton

Abstract According to some theories of gravity, antimatter will fall faster than matter in the earth's gravitational field. An experiment to measure the gravitational force on the antiproton is under construction. Antiprotons of a few MeV from the LEAR facility of CERN will be slowed down and caught in a large Penning electromagnetic trap. They will then be cooled and transferred to Penning cooling and launching traps. The gravitational acceleration will be measured by time of flight in a drift tube shielding stray electric fields, and will be compared with that measured for H− ions. Progress on a number of fronts is described.
Studies of Silyl-Accelerated 1,5-Hydrogen Migrations in Vinylcyclopropanes

Thermal 1,5-hydrogen (retro-ene) rearrangements of 1-silylmethylated 2-vinylcyclopropanes have been studied. cis-1-Silylmethyl-2-vinylcyclopropanes 17 and 19 undergo facile 1,5-hydrogen transposition upon mild thermolysis in benzene or toluene solution (80−110 °C) to give nearly quantitative yields of ring-opened 1-silyl-1,4-diene products. These reactions occur at temperatures at least 100 °C lower than those of the nonsilylated substrates. The silicon center and its ligands influence both the rate and stereoselectivity of diene formation, with the triphenylsilyl substrate providing the fastest reaction and highest (exclusive) stereoselectivity in forming the diene, regardless of the E/Z geometry of the vinylcyclopropane. The trimethylsilyl and triethoxysilyl compounds (19b and 19c) rearrange more slowly and with lower stereoselectivity. It is proposed that the rearrangement process takes place via a concerted suprafacial migration by one of two diastereotopic methylene hydrogens through a transition sta...
Determination of geopotential coefficients by efficient numerical integration techniques

An efficient, high-accuracy, double-integration method that evaluates the iterated form of the surface integral representations of the geopotential coefficients is presented.. The efficiency and high accuracy of this method is obtained by the utilization of the Romberg numerical integration scheme. Additional efficiency is obtained by computing the inner integral common to many different coefficients only once. This method was tested using a test case earth that represented the basic features of the earth's potential field.
Microlens Parallaxes of Binary Lenses Measured from a Satellite

Caustic-crossing binary lenses make up about 5% of all detected microlenses. The relative proper motion of a caustic-crossing binary lens can be measured with observations from a single terrestrial telescope. Thus, uniquely, binary lenses can be completely solved with only the addition of a measurement of the microlensing parallax. This solution will yield the mass, distance, and transverse velocity of the lens relative to the source. To date, only one of the ~1000 observed microlensing events has been so solved. We examine the ability of a parallax satellite combined with ground-based observations to solve these events. To measure both components of the vector parallax, the lens must be observed near two different caustics. Thus, the final accuracy is determined mostly by whether one can intensively monitor part of the first caustic crossing, by the magnification pattern, and by the path of the source with respect to the lens geometry. We find that vector parallaxes can be measured far more easily for binary lenses than single lenses, requiring 1-3 orders of magnitude fewer photons. They may thus yield a large number of completely solved lenses relatively cheaply.
Trianion Synthon Approach to Spirocyclic Heterocycles

A variety of spirocyclic heterocycles have been constructed by a double-alkylation and reductive cyclization approach utilizing α-heteroatom nitriles as trianion synthons. The method provides access to heteroatom-substituted spirocycles in a variety of ring sizes that are found in natural products and are important in pharmaceutical lead development and optimization.
On the generalized Hamming weights of convolutional codes

Motivated by applications in cryptology, Wei (1991) introduced the concept of a generalized Hamming weight for a linear block code. In this correspondence, we define generalized Hamming weights for the class of convolutional codes and we derive several of their basic properties. By restricting to convolutional codes having a generator matrix G(D) with bounded Kronecker indices we are able to derive upper and lower bounds on the weight hierarchy.
Corporate Insurance and Managerial Incentives

Abstract We present an agency model to examine the use of corporate insurance by publicly held firms. We assume that insurance companies serve as investigators verifying whether or not accidents were insured. When the manager performs multiple tasks to reduce the expected number of accidents, the verification results can be used to produce a pair of managerial performance measures. We show that the optimal pair of performance measures can be obtained when the corporate insurance policy covers all uncontrollable accidents and some controllable accidents that are “costlier” for the manager to control.Journal of Economic LiteratureClassification Numbers: C61, C73, D82, G22, L14.
Orientational dependence of vicinal proton-proton NMR coupling constants: The Karplus relationship

Vicinal proton-proton coupling constants depend on a variety of stereochemical parameters such as bond angle, bond length, substituent electronegativity and orientation, and — most importantly — on the torsion angle between the coupling protons. The sensitivity of vicinal proton-proton coupling constants 3JHH′, to variations of dihedral angle ϕwas first rationalized in valence bond terms by Karplus, who showed that the coupling constants could be approximately fitted to a cos2ϕ function. The Karplus equation 3JHH′ = Acos2ϕ + Bcosϕ + C (or variants thereof) has been a major tool of the structural chemist for 35 years. Karplus started with the Ramsey formula for Fermi contact contribution, expressed by ground-state wave functions and a mean excitation energy. More sophisticated molecular orbital (MO) treatments have afforded analogous expressions that may be used to predict trends correctly but are rarely useful for accurate estimations of dihedral angles. Numerous attempts have been made to account for the effect of substituents, bond angles, and lengths — either empirically by the choice of A, B, and C (with different values for each type of compound) or semiempirically, starting with theoretically more sophisticated expressions with statistically adjustable parameters. Theoretical and empirical approaches are reviewed and compared.
Triple ionization of lithium by electron impact.

Ejection of the three electrons from lithium in a single electron collision has been observed for the first time. Triply charged lithium was observed in an ion time-of-flight spectrum following electron impact on a sample of ultracold, trapped lithium. The higher signal/background afforded by the trap environment made the observation of ${\mathrm{L}\mathrm{i}}^{3+}$ possible. We measured the ratios of triple-to-double and double-to-single ionization at an impact energy of 1000 eV. The $3+/2+$ ratio is $\ensuremath{\approx}0.001$, a value 2 orders of magnitude lower than semiempirical predictions. We present a simple method that uses photoionization data combined with sum-rule analysis to predict the asymptotic charge-state ratios. The sum-rule predictions compare reasonably with experiment and shake calculations, but disagree sharply with the semiempirical estimates.
An Isometric Dynamics for a Causal Set Approach to Discrete Quantum Gravity

We consider a covariant causal set approach to discrete quantum gravity. We first review the microscopic picture of this approach. In this picture a universe grows one element at a time and its geometry is determined by a sequence of integers called the shell sequence. We next present the macroscopic picture which is described by a sequential growth process. We introduce a model in which the dynamics is governed by a quantum transition amplitude. The amplitude satisfies a stochastic and unitary condition and the resulting dynamics becomes isometric. We show that the dynamics preserves stochastic states. By “doubling down” on the dynamics we obtain a unitary group representation and a natural energy operator. These unitary operators are employed to define canonical position and momentum operators.
A Birth-Death Markov Chain Monte Carlo Method to Estimate the Number of States in a State-Contingent Production Frontier Model

In this article we estimate a state-contingent production frontier for a group of farms while endogenously estimating the number of states of nature induced by unobserved environmental variables. This estimation is conducted by using a birth-death Markov chain Monte Carlo method. State-contingent output is estimated conditioned on an observed input vector and an a priori unknown number of unobserved states, each of which is modeled as a component of a mixture of Gaussian distributions. In a panel data application, state-independent dummy variables are used to control for time effects. The model is applied to 44 rice farms in the Philippines operating between 1990 and 1997. The endogenous estimation procedure indicates a unimodal posterior probability distribution on the number of states, with a median of three states. The estimated posterior coefficient values and their economic implications are compared to those of previous research that had assumed a fixed number of states determined exogenously. Goodness-of-fit testing is performed for the first time for a state-contingent production model. The results indicate satisfactory fit and also provide insights regarding the degree of estimation error reduction achieved by utilizing a distribution for the number of states instead of a point estimate. All of our models show significant improvement in terms of mean squared error of in-sample predictions against previous work. This application also demonstrates that using a state-independent dummy time trend instead of a state-contingent linear time trend leads to slightly smaller differences in state mean output levels, although input elasticities remain state-contingent.
RNA-dependent RNA polymerases of plants.

Abstract The existence of RNA-dependent RNA polymerases (EC 2.7.7.48) in plants has been definitely proven by their isolation in pure form from cucumber and tobacco in our laboratory and from cowpea at Wageningen. These enzymes are single-chain proteins of 100-130 kilodaltons. They show clear physical and biochemical differences characteristic for a given plant species, even when their amounts in the plants were greatly increased prior to isolation by infection with the same virus. The role of these enzymes in plant physiology remains unknown.
Bending and shear damping in beams: Frequency domain estimation techniques

In this paper we consider damping mechanisms in the context of dynamic beam models. We summarize previous efforts on various damping models (strain rate or Kelvin-Voigt, time hysteresis (Boltzmann), spatial hysteresis, bending rate/square root) for the Euler-Bernoulli beam theory. The Euler-Bernoulli theory is known to be inadequate for experiments in which high frequency modes have been excited. In such cases the Timoshenko theory may be more appropriate; we consider a number of damping hypotheses for this theory. Corresponding models are proposed and compared to experimental data in the context of parameter estimation or identification problems formulated in the frequency domain. Theoretical results related to the convergence of approximations to these infinite dimensional distributed parameter system estimation problems are presented. Associated computational findings for specific beam experiments are discussed.
Rotational correlation and dynamic heterogeneity in a kinetically constrained lattice gas

We study the dynamical heterogeneity and glassy dynamics in a kinetically constrained lattice-gas model which has both translational and rotational degrees of freedom. We find that the rotational relaxation time tracks the structural relaxation time as density is increased whereas the translational diffusion constant exhibits a strong decoupling. We investigate distributions of exchange and persistence times for both the rotational and translational degrees of freedom and compare our results on the distributions of rotational exchange times to recent single molecule studies.