cssi/SciSciGPT-SciSciNet huggingface dataset:
Novel amino-aryloxycyclotriphosphazene polymer precursors and intermediates: Solvent dependent synthesis and characterization

Abstract An efficient synthesis of tris(4-nitrophenoxy)tris(phenoxy)cyclotriphosphazene starting from hexachlorocyclotriphosphazene is described for varied reaction conditions. Two stereoisomers of tris(4-nitrophenoxy)tris(phenoxy)cyclotriphosphazenes ( III and III *) have shown melting points of 111–112°C and 133–135°C, respectively. A process has been given to separate III and III * by chemical crystallization from a reaction product. The low-pressure hydrogenation of III and III * in solution in the presence of the catalyst platinum oxide has resulted in the reduction of nitro groups to the corresponding stereoisomers tris(4-aminophenoxy)tris(phenoxy)cyclotriphosphazenes IV and IV *, melting at 161–162°C and 107–108°C, respectively. All the products have been characterized by 31 P NMR, FT-IR, 1 H NMR, mass spectrometry and elemental analysis. Differential scanning calorimetry has been used to determine their melting behaviour.
Congestion tolling with agglomeration externalities

Abstract Consider an urban economy with two types of externalities, negative traffic congestion externalities and positive agglomeration externalities deriving from non-market interaction. Suppose that urban travel can be tolled, that non-market interaction cannot be subsidized, and that non-market interaction is stimulated by a reduction in travel costs. Then the optimal toll is below the congestion externality cost. This paper explores this line of reasoning.
Delay Model for Planning Analysis of Main-Line Toll Plazas

Main-line toll plazas are major bottlenecks on toll roads. The capacity and level-of-service analysis of these facilities, however, have not been addressed by the various versions of the Highway Capacity Manual. Traffic operations at toll plazas can be realistically analyzed through computer simulation, but there is a need for a simple analytical delay model that can provide quick and reasonably accurate estimates to help with the planning of toll plazas. Such a delay model is formulated and calibrated on the basis of simulation results. For volume to capacity ratios below 1.4, discrepancies between the estimates obtained from this delay model and from computer simulation are mostly less than 10 percent.
Quasi-Hermitian quantum mechanics in phase space

We investigate quasi-Hermitian quantum mechanics in phase space using standard deformation quantization methods: Groenewold star products and Wigner transforms. We focus on imaginary Liouville theory as a representative example where exact results are easily obtained. We emphasize spatially periodic solutions, compute various distribution functions and phase-space metrics, and explore the relationships between them.
The Role of an Ethics Committee in Resolving Conflict in the Neonatal Intensive Care Unit

What should be the role of an institutional ethics committee (IEC) in resolving conflict concerning patient care decisions in the neonatal intensive care unit (NICU)? This question takes on added importance in light of recent court decisions which suggest that IEC deliberations may serve as persuasive evidence in court, of proposed state regulations that would establish an IEC as an alternative to judicial review, and of recent Joint Commission on Accreditation of Healthcare Organizations (JCAHO) guidelines that require an institutional policy on limitation or withdrawal of treatment to include a specified mechanism for resolving conflict. Unfortunately, despite these developments, prospective case consultation remains one of the most controversial and poorly understood aspects of IEC functions. Questions and concerns persist about the relation the IEC has and should have to actual decisions in specific cases. We briefly examine the clinical, organizational, and regulatory complexity of the NICU environment and suggest five potential sources of uncertainty, disagreement, and conflict among parent(s) and NICU staff.
Transformation Electromagnetics Devices Based on Printed-Circuit Tensor Impedance Surfaces

A method for designing transformation electromagnetics devices using tensor impedance surfaces is presented. The method is first applied to idealized tensor impedance boundary conditions (TIBCs), and later to printed-circuit tensor impedance surfaces (PCTISs). A PCTIS is a practical realization of a TIBC. It consists of a tensor impedance sheet, which models a subwavelength patterned metallic cladding, over a grounded dielectric substrate. The method outlined in this paper allows anisotropic TIBCs and PCTISs to be designed that support tangential wave vector distributions and power flow directions specified by a coordinate transformation. As an example, beam-shifting devices are designed, using TIBCs and PCTISs, that allow a surface wave to be shifted laterally. The designs are verified with a commercial full-wave electromagnetic solver. This work opens new opportunities for the design and implementation of anisotropic and inhomogeneous printed-circuit or graphene-based surfaces that can guide or radiate electromagnetic fields.
Computational Simulation and Experimental Measurements for a Delta Wing with Periodic Suction and Blowing

The low-speed, laminar flowfield for a 70-deg sweep delta wing is investigated. Solutions to the unsteady, three-dimensional, compressible Navier-Stokes equations were obtained on an unstructured grid to match results from an experiment performed in a water tunnel. The experiment was conducted with the delta wing at an angle of attack of 35 deg and the freestream flow at a root-chord Reynolds number of 4.07 × 10 4 . Particle image velocimetry measurements were made for the flowfield while periodic suction and blowing was taking place along the delta wing leading edge. The computational results are analyzed and compared with the experimental results to show how computations and experiments can be conducted in a synergistic fashion. Details about the primary vortex location, vortex burst, secondary vortex, and shear layer interaction are shown and discussed
Sensor-based control systems for arc welding robots☆

Arc welding is one of the most important areas of application for industrial robots. In most manufacturing situations, uncertainties in dimensions of the part, geometry of the joint, and the welding process itself make the use of sensors essential to maintaining weld quality. In this paper three types of control systems for arc welding robots are described: (1) tracking systems for centering the weld puddle over the joint, (2) weld process controls for maintaining proper seam width and penetration, and (3) supervisory controls for sequencing welding operations. These control functions have been implemented successfully in production using a computer vision sensor integrated into the welding torch. Experimental results are presented demonstrating the capabilities of the system.
Finite temperature wave-function renormalization: A comparative analysis

We compare two competing theories regarding finite temperature wave-function corrections for the process H{r_arrow}e{sup +}e{sup {minus}} and for n+{nu}{r_arrow}p+e{sup {minus}} and related processes of interest for primordial nucleosynthesis. Although the two methods are distinct (as shown in H{r_arrow}e{sup +}e{sup {minus}}) they yield the same finite temperature correction for all n{r_arrow}p and p{r_arrow}n processes. Both methods yield an increase in the He/H ratio of 0.01{percent} due to finite temperature renormalization rather than a decrease of 0.16{percent} as previously predicted. {copyright} {ital 1997} {ital The American Physical Society}
Implications of defect clusters formed in cascades on free defect generation and microstructural development

A large fraction of the defects produced by irradiation with energetic neutrons or heavy ions originates in cascades. Not only increased recombination of vacancy and interstitial defects but also significant clustering of like defects occur. Both processes reduce the number of point defects available for long range migration. Consequences of defect clustering in cascades will be discussed in a semi-quantitative form with the aid of calculations using a very simplified model: Quasi-steady-state distributions of immobile vacancy and/or interstitial clusters develop which, in turn, can become significant sinks for mobile defects, and, therefore reduce their lifetime. Although cluster sinks will cause segregation and, potentially, precipitation of second phases due to local changes of composition, the finite lifetime of clusters will not lead to lasting, local compositional changes. A transition from highly dense interstitial and vacancy cluster distributions to the void swelling regime occurs when the thermal evaporation of vacancies from small vacancy clusters becomes significant at higher temperatures. Unequal clustering of vacancies and interstitials leads to an imbalance of their fluxes of in the matrix and, hence, to unequal contributions to atom transport by interstitials and by vacancies even in the quasi-steady state approximation.
CUBIC: identification of regulatory binding sites through data clustering.

Transcription factor binding sites are short fragments in the upstream regions of genes, to which transcription factors bind to regulate the transcription of genes into mRNA. Computational identification of transcription factor binding sites remains an unsolved challenging problem though a great amount of effort has been put into the study of this problem. We have recently developed a novel technique for identification of binding sites from a set of upstream regions of genes, that could possibly be transcriptionally co-regulated and hence might share similar transcription factor binding sites. By utilizing two key features of such binding sites (i.e. their high sequence similarities and their relatively high frequencies compared to other sequence fragments), we have formulated this problem as a cluster identification problem. That is to identify and extract data clusters from a noisy background. While the classical data clustering problem (partitioning a data set into clusters sharing common or similar features) has been extensively studied, there is no general algorithm for solving the problem of identifying data clusters from a noisy background. In this paper, we present a novel algorithm for solving such a problem. We have proved that a cluster identification problem, under our definition, can be rigorously and efficiently solved through searching for substrings with special properties in a linear sequence. We have also developed a method for assessing the statistical significance of each identified cluster, which can be used to rule out accidental data clusters. We have implemented the cluster identification algorithm and the statistical significance analysis method as a computer software CUBIC. Extensive testing on CUBIC has been carried out. We present here a few applications of CUBIC on challenging cases of binding site identification.
Ribosome Profiling Provides Evidence that Large Noncoding RNAs Do Not Encode Proteins

Large noncoding RNAs are emerging as an important component in cellular regulation. Considerable evidence indicates that these transcripts act directly as functional RNAs rather than through an encoded protein product. However, a recent study of ribosome occupancy reported that many large intergenic ncRNAs (lincRNAs) are bound by ribosomes, raising the possibility that they are translated into proteins. Here, we show that classical noncoding RNAs and 5′ UTRs show the same ribosome occupancy as lincRNAs, demonstrating that ribosome occupancy alone is not sufficient to classify transcripts as coding or noncoding. Instead, we define a metric based on the known property of translation whereby translating ribosomes are released upon encountering a bona fide stop codon. We show that this metric accurately discriminates between protein-coding transcripts and all classes of known noncoding transcripts, including lincRNAs. Taken together, these results argue that the large majority of lincRNAs do not function through encoded proteins.
Stable concordance of knots in $3$–manifolds

Knots and links in 3-manifolds are studied by applying intersection invariants to singular concordances. The resulting link invariants generalize the Arf invariant, the mod 2 Sato-Levine invariants, and Milnor's triple linking numbers. Besides fitting into a general theory of Whitney towers, these invariants provide obstructions to the existence of a singular concordance which can be homotoped to an embedding after stabilization by connected sums with $S^2\times S^2$. Results include classifications of stably slice links in orientable 3-manifolds, stable knot concordance in products of an orientable surface with the circle, and stable link concordance for many links of null-homotopic knots in orientable 3-manifolds.
Random perturbations of 2-dimensional hamiltonian flows

We consider the motion of a particle in a periodic two dimensional flow perturbed by small (molecular) diffusion. The flow is generated by a divergence free zero mean vector field. The long time behavior corresponds to the behavior of the homogenized process - that is diffusion process with the constant diffusion matrix (effective diffusivity). We obtain the asymptotics of the effective diffusivity when the molecular diffusion tends to zero.
Germline and Somatic Mutations in the Tyrosine Kinase Domain of the MET Proto-Oncogene in Papillary Renal Carcinomas

Hereditary papillary renal carcinoma (HPRC) is a recently recognized form of inherited kidney cancer characterized by a predisposition to develop multiple, bilateral papillary renal tumours. The pattern of inheritance of HPRC is consistent with autosomal dominant transmission with reduced penetrance. HPRC is histologically and genetically distinct from two other causes of inherited renal carcinoma, von Hippel-Lindau disease (VHL) and the chromosome translocation (3;8). Malignant papillary renal carcinomas are characterized by trisomy of chromosomes 7, 16 and 17, and in men, by loss of the Y chromosome. Inherited and sporadic clear cell renal carcinomas are characterized by inactivation of both copies of the VHL gene by mutation, and/or by hypermethylation. We found that the HPRC gene was located at chromosome 7q31.1-34 in a 27-centimorgan (cM) interval between D7S496 and D7S1837. We identified missense mutations located in the tyrosine kinase domain of the MET gene in the germline of affected members of HPRC families and in a subset of sporadic papillary renal carcinomas. Three mutations in the MET gene are located in codons that are homologous to those in c-kit and RET, proto-oncogenes that are targets of naturally-occurring mutations. The results suggest that missense mutations located in the MET proto-oncogene lead to constitutive activation of the MET protein and papillary renal carcinomas.
Combining ECC with modulation: performance comparisons

A technique for combining error correcting codes (ECCs) with modulation codes of the block type is described. Its performance is analyzed with respect to the traditional method in magnetic recording, which involves the concatenation of error-correcting code with a convolutional modulation code. Conditions are established under which the new method is superior to the concatenated scheme. For a fixed number of information bits, the total redundancy with the two methods is calculated and conditions are established under which the redundancy of the new method is smaller than the redundancy of the traditional method. In particular, performance with respect to the
Facile Synthesis of (ω-Bromoalkyl)trimethylammonium Bromides

Abstract Reaction of a 1,ω-dibromoalkane with trimethylamine in THF at room temperature precipitates the corresponding (ω-bromoalkyl)trimethylammonium bromide to cleanly form the mono-substituted product in the absence of the bis-quat salt.
Writing, dictating, and speaking letters

It is commonly assumed that dictation requires a long time to learn, but authors eventually dictate much faster than they write. Performance results now show that novice dictators can learn in a few hours to dictate with the speed and quality with which they write. However, they do not think they perform this well. Dictators with years of experience are from zero to 25 percent faster than novices, depending upon the complexity of the letters. Planning time is about two-thirds of composition time, regardless of the method of composition.
Processing and Properties of Cellular Silica Synthesized by Foaming Sol‐Gels

A novel process for fabricating lightweight, cellular ceramics from sols is presented. The process utilizes the rapid viscosity change during gelation to stabilize the structure of a foamed silica sol. Manipulation of gel viscosity and foaming agent concentration resulted in a minimum cell size of 90 μm at 31% density and minimum density of 17% with average cell size of 400 μm. The flexural strength compared favorably with space shuttle tiles and sintered hollow glass spheres. From −50° to 150°C, the dielectric constant ranged from 1.51 to 1.55 for a 20% dense foam and was slightly dispersive, whereas the dielectric loss was comparable with fused silica.
Robust fixed-structure controller synthesis using the implicit small-gain bound

Abstract In this paper we explore the applicability of the implicit small-gain guaranteed cost bound for controller synthesis. For flexibility in controller synthesis, we adopt the approach of fixed-structure controller design which allows consideration of arbitrary controller structures, including order, internal structure, and decentralization. A numerical example that has been addressed in the literature by means of alternative guaranteed cost bounds is presented to demonstrate the fixed-structure/implicit small-gain approach to robust controller synthesis.
INVESTIGATING THE POTENTIAL DILUTION OF THE METAL CONTENT OF HOT GAS IN EARLY-TYPE GALAXIES BY ACCRETED COLD GAS

The measured emission-weighted metal abundance of the hot gas in early-type galaxies has been known to be lower than theoretical expectations for 20 years. In addition, both X-ray luminosity and metal abundance vary significantly among galaxies of similar optical luminosities. This suggests some missing factors in the galaxy evolution process, especially the metal enrichment process. With Chandra and XMM-Newton, we studied 32 early-type galaxies (kT {approx}< 1 keV) covering a span of two orders of L{sub X,gas}/L{sub K} to investigate these missing factors. Contrary to previous studies that X-ray faint galaxies show extremely low Fe abundance ({approx}0.1 Z{sub Sun }), nearly all galaxies in our sample show an Fe abundance at least 0.3 Z{sub Sun }, although the measured Fe abundance difference between X-ray faint and X-ray bright galaxies remains remarkable. We investigated whether this dichotomy of hot gas Fe abundances can be related to the dilution of hot gas by mixing with cold gas. With a subset of 24 galaxies in this sample, we find that there is virtually no correlation between hot gas Fe abundances and their atomic gas content, which disproves the scenario that the low metal abundance of X-ray faint galaxies might be a result of more » the dilution of the remaining hot gas by pristine atomic gas. In contrast, we demonstrate a negative correlation between the measured hot gas Fe abundance and the ratio of molecular gas mass to hot gas mass, although it is unclear what is responsible for this apparent anti-correlation. We discuss several possibilities including that externally originated molecular gas might be able to dilute the hot gas metal content. Alternatively, the measured hot gas Fe abundance may be underestimated due to more complex temperature and abundance structures and even a two-temperature model might be insufficient to reflect the true value of the emission weighted mean Fe abundance. « less
Remote object recognition by analysis of surface structure

We present a new algorithm for the discrimination of remote objects by their surface structure. Starting from a range-azimuth profile function, we formulate a range-azimuth matrix whose largest eigenvalues are used as discriminating features to separate object classes. A simpler, competing algorithm uses the number of sign changes in the range-azimuth profile function to discriminate among classes. Whereas both algorithms work well on noiseless data, an experiment involving real data shows that the eigenvalue method is far more robust with respect to noise than is the sign-change method. Two well-known methods based on surface structure, variance, and fractal dimension were also tested on real data. Neither method furnished the aspect invariance and the discriminability of the eigenvalue method.
Why 3+1 metric rather than 4+0 or 2+2?

Abstract Why does the physical 4-dimensional space have a 3+1 signature rather than a 4+0 or a 2+2 for its metric? We give a simple explanation based largely on a group-theoretic argument a la Wigner. Applied to flat spaces of higher dimensions the same approach indicates that metrics with more than one time dimension are physically unacceptable because the corresponding irreducible unitary representations are infinite dimensional (besides the trivial representation).
Schedule Recovery: Unplanned Absences in Service Operations*

The U.S. service sector loses 2.3% of all scheduled labor hours to unplanned absences, but in some industries, the total cost of unplanned absences approaches 20% of payroll expense. The principal reasons for unscheduled absences (personal illness and family issues) are unlikely to abate anytime soon. Despite this, most labor scheduling systems continue to assume perfect attendance. This oversight masks an important but rarely addressed issue in services management: how to recover from short-notice, short-term reductions in planned capacity. In this article, we model optimal responses to unplanned employee absences in multi-server queueing systems that provide discrete, pay-per-use services for impatient customers. Our goal is to assess the performance of alternate absence recovery strategies under various staffing and scheduling regimes. We accomplish this by first developing optimal labor schedules for hypothetical service environments with unreliable workers. We then simulate unplanned employee absences, apply an absence recovery model, and compute system profits. Our absence recovery model utilizes recovery strategies such as holdover overtime, call-ins, and temporary workers. We find that holdover overtime is an effective absence recovery strategy provided sufficient reserve capacity (maximum allowable work hours minus scheduled hours) exists. Otherwise, less precise and more costly absence recovery methods such as call-ins and temporary help service workers may be needed. We also find that choices for initial staffing and scheduling policies, such as planned overtime and absence anticipation, significantly influence the likelihood of successful absence recovery. To predict the effectiveness of absence recovery policies under alternate staffing/scheduling strategies and operating environments, we propose an index based on initial capacity reserves.
Verified interoperable implementations of security protocols

We present an architecture and tools for verifying implementations of security protocols. Our implementations can run with both concrete and symbolic implementations of cryptographic algorithms. The concrete implementation is for production and interoperability testing. The symbolic implementation is for debugging and formal verification. We develop our approach for protocols written in Fn, a dialect of ML, and verify them by compilation to ProVerif, a resolution-based theorem prover for cryptographic protocols. We establish the correctness of this compilation scheme, and we illustrate our approach with protocols for Web Services security.
Functional materials from self-assembled bis-urea macrocycles.

ConspectusThis Account highlights the work from our laboratories on bis-urea macrocycles constructed from two C-shaped spacers and two urea groups. These simple molecular units assembled with high fidelity into columnar structures guided by the three-centered urea hydrogen bonding motif and aryl stacking interactions. Individual columns are aligned and closely packed together to afford functional and homogeneous microporous crystals. This approach allows for precise and rational control over the dimensions of the columnar structure simply by changing the small molecular unit. When the macrocyclic unit lacks a cavity, columnar assembly gives strong pillars. Strong pillars with external functional groups such as basic lone pairs can expand like clays to accept guests between the pillars. Macrocycles that contain sizable interior cavities assemble into porous molecular crystals with aligned, well-defined columnar pores that are accessible to gases and guests. Herein, we examine the optimal design of the macr...
The impact of characteristic impedance on waveform calibrations

We examine the impact of characteristic impedance on mismatch corrections for temporal waveform calibrations based on high-speed electro-optic sampling measurements. We show that failing to measure and account for the characteristic impedance of coplanar lines can lead to statistically significant errors in the calibrations in both the time and frequency domains.
Theory and Methodology of Optimally Measuring Vibratory Strains in Closely Spaced Modes

Stress ratios are traditionally used to infer maximum stresses in blades from strain measurements. This method may not be applicable to all the modes of modern low aspect ratio (LAR) blades since LAR blades often have high frequency tip modes that are so closely spaced that slight changes in structural properties can cause significant mode shape changes. In this paper, it is first shown that the actual tip modes of a LAR blade can be well approximated as linear combinations of the ''nominal'' modes. The stress field of the blade can then be estimated by calculating the modal content from multiple strain measurements. However, since placement and gage inaccuracies can introduce significant errors in the calculation, it is necessary to find the optimal gage placement that minimizes the error in estimated stresses. An error estimate using norms' and an efficient optimization method are developed for this purpose.
Can We Identify Union Productivity Effects

Contrary to recent criticism, the standard production function test can, in principle, reveal whether or not unionized workers or firms are more productive than their nonunion counterparts. In the long run, however, the forces of competition foreordain the result.
Reduction of 2-Arylthio-β- C - D -Glucopyranosides with Different Functional Groups in the Lateral Chain

Abstract 2-Arylthio-β-C-D-glucopyranosides with a carbonyl or methoxy group in the lateral chain (1 and 2) can be converted to the corresponding 2-deoxy-β-C-D-glucopyranosides (1a and 2a) using Raney Ni. Reduction of 2-arylthio-β-C-D-glucopyranosides bearing an ester, methoxy, C≡N, or C=C moiety in the side chain (3–6) using n-Bu3SnH in the presence of azobisisobutyronitrile (AIBN) provided the corresponding 2-deoxy-β-C-D-glucopyranosides (3a–6a) without reducing additional functional groups. The application of n-Bu3SnH and AIBN in reaction with 2-arylthio-β-C-D-glucopyranoside (7) containing a Me3Si group bonded to the carbonyl fragment (7) resulted in the reduction of both the 2-ArS and C=O groups.
Adjuvant oral alkylating chemotherapy in patients with stage i epithelial ovarian cancer

From November 1973 to May 1986, 50 patients with Stage I epithelial ovarian cancer were treated at the University of Kentucky Medical Center (Lexington, KY) with oral Alkeran (melphalan) chemotherapy after primary surgery. Twenty-two patients had Grade 1 tumors, 23 patients had Grade 2 tumors, and five patients had Grade 3 tumors. Patients with ovarian tumors of borderline malignancy were excluded from this study. Twenty-eight patients received from six to 11 courses of chemotherapy and 22 patients completed 12 courses of chemotherapy. Chemotherapy was well tolerated and no patient died of chemotherapy-related complications. Thirty-eight patients underwent second-look laparotomy died of disease 41 months after diagnosis and one patient died with no evidence of disease 6 months after treatment. The actuarial survival of the total group of patients was 98% at 2 years and 94% at 5 years. Fewer than 12 months of chemotherapy may be necessary to obtain long-term survival in these patients.
Benzothiazines in Synthesis. Further Studies of the Intramolecular, Stereoselective Addition of Sulfonimidoyl Carbanions to α,β-Unsaturated Functional Groups

A variety of alkenes substituted by electron-withdrawing groups serve as competent electrophiles for the stereoselective, intramolecular nucleophilic addition of sulfonimidoyl carbanions to form benzothiazines. This reaction generally proceeds with complete stereoselectivity within the limits of our detection. In some cases, benzothiazine formation occurs in a single pot at relatively high temperatures during N-arylation of the simple sulfoximine used in this study. Yet, the process occurs with the same direction and extent of stereoselectivity as that seen when the Michael addition is performed at very low temperatures.
Regiospecific functionalization of methyl C-H bonds of alkyl groups in reagents with heteroatom functionality.

We report the regiospecific, rhodium-catalyzed borylation of saturated terminal C−H bonds in molecules with existing functionality. Moderate to good yields were obtained with the organic substrate in excess and as limiting reagent. The borylations of trialkylamines, protected alcohols, protected ketones, and fluoroalkanes occurred regiospecifically at the methyl group that is least sterically hindered. Reactions were also conducted that probed electronic effects on the alkyl borylation. These reactions showed that the borylation occurred preferentially at the methyl group that is most electron-deficient. Methods to conduct tandem borylation of C−H bonds and conversion of the resulting boronate esters to alcohols, alkylarenes, and alkyltrifluoroborates were also developed.
Dynamic spectrum allocation: the impotency of duration notification

For the classic dynamic storage/spectrum allocation problem, we show that knowledge of the durations of the requests is of no great use to an on-line algorithm in the worst case. This answers an open question posed by Naor et al. [9]. More precisely, we show that the competitive ratio of every randomized algorithm against an oblivious adversary is Ω(log x/log log x), where x may be any of several different parameters used in the literature. It is known that First Fit, which does not require knowledge of the durations of the task, is logarithmically competitive in these parameters. Copyright © 2000 John Wiley & Sons, Ltd.
Global and approximate global optimality of myopic economic decisions

Abstract A general discrete-time stochastic control model is developed which encompasses many well-known economic models. In the context of the general model, sufficient conditions are derived for the equivalence and approximate equivalence of myopic (sequential single-period) and global (simultaneous multi-period) expected return maximization. A bound provided for the global return loss resulting from myopic optimization is shown to vary directly with the degree of uncertainty and inversely with the degree of positive correlation in period-by-period returns. Characteristics of intermediate-period return functions which partially order them in terms of final-period expected return performance are clarified. Results are illustrated by portfolio and macro policy model examples.
Guidelines for the use of infinite source queueing models in the analysis of computer system performance

Mathematical models based on queueing theory are widely used in the analysis of computer system performance. As in the case of other engineering disciplines, these models never correspond exactly to the real systems they are intended to represent. However, if the associated error terms are sufficiently small the models can still serve as valuable tools for estimating performance levels in specific cases and for studying the factors which influence overall system behavior. In this paper we examine some error terms which arise when the familiar M/G/1 queueing model is used to predict expected response times and queue lengths in systems which contain only a finite number of sources.
On the Similarity between Cluster and Galactic Stellar Initial Mass Functions

The stellar initial mass functions (IMFs) for the Galactic bulge, the Milky Way, other galaxies, clusters of galaxies, and the integrated stars in the universe are composites from countless individual IMFs in star clusters and associations where stars form. These galaxy-scale IMFs, reviewed in detail here, are not steeper than the cluster IMFs except in rare cases. This is true even though low-mass clusters generally outnumber high-mass clusters and the average maximum stellar mass in a cluster scales with the cluster mass. The implication is that the mass distribution function for clusters and associations is a power law with a slope of -2 or shallower. Steeper slopes, even by a few tenths, upset the observed equality between large- and small-scale IMFs. Such a cluster function is expected from the hierarchical nature of star formation, which also provides independent evidence for the IMF equality when it is applied on subcluster scales. We explain these results with analytical expressions and Monte Carlo simulations. Star clusters appear to be the relaxed inner parts of a widespread hierarchy of star formation and cloud structure. They are defined by their own dynamics rather than by preexisting cloud boundaries.
Partial Anticipation and the Gains to Bank Merger Targets

We design an empirical model to determine the prior probability of a bank becoming an acquisition target. We find that the probability of a bank being acquired is higher for banks that are larger, have a lower return on assets, a higher capital level, more non-performing loans, higher runup in price, a lower market-to-book multiple, a higher core deposit ratio, and a higher loan concentration. The probability is also higher since the passage of the Riegle–Neal Act of 1994. We also examine whether the full gains to target banks are conditioned on the probability of being acquired. We find that the gains to target banks in the one-year pre-announcement period are more pronounced for banks that exhibit high-logit probability characteristics. The gains are large and significant in the short-term announcement period, but not significantly related to the logit probabilities among banks. Our results suggest that the share price adjustment for the characteristics that make some banks more appealing targets appears to be completed in the pre-announcement period. Thus, studies that estimate the gains to targets using only the announcement period are underestimating the gains.
Keck studies of M31's stellar halo

We present Keck 10-meter/LRIS spectra of candidate red giants in the halo of M31, located at a projected radius of R equals 19kpc on the minor axis. These spectroscopic targets have been selected using a combination of UBRI-based and morphological screening to eliminate background galaxies. Radial velocity measurements are used to separate M312 halo giants from foreground Milky Way dwarf stars, M31 disk stars, and residual background galaxies. The metallicity of each M31 halo giant is measured using standard photometric and spectroscopic techniques, the latter based on the strength of the Ca II triplet. The various (Fe/H) estimates are in rough agreement with one another. The data reveal a large spread in (Fe/H) in M31's halo; there is no strong radial (Fe/H) gradient. LRIS and HIRES spectra are also presented for red giants in five dwarf spheroidal satellites of M31: AndI, AndIII, AndV, AndVI, and AndVII. There appears to be a significant metallicity spread in AndVI and possibly in AndI. The new radial velocity data on these outer dwarfs are used to constrain the total mass of M31: the best estimate in under 10 12 M, somewhat less than the best estimate for the Milky Way.
Quantum z-algebras and representations of quantum affine algebras

Generalizing our earlier work, we introduce the homogeneous quantum Z-algebras for all quantum affine algebras U q(gcirc;) of type one. With the new algebras we unite previously scattered realizations of quantum affine algebras in various cases. As a result we find a realization of .
The proportional random allocation of indivisible units

Indivisible units are randomly allocated among agents with a claim/demand on the resources. The available resources fall short of the sum of individual claims. The proportional method distributes units sequentially, and the probability of receiving a unit at any step is proportional to the unsatisfied claims. We characterize the family of probabilistic rationing methods meeting the three axioms Consistency, Lower and Upper Composition. It contains the proportional method, all deterministic fixed priority methods, and the priority compositions of proportional methods. The proportional method is the only fair method in the family.
Beyond separation of duty: An algebra for specifying high-level security policies

The process of introducing security controls into a sensitive task, which we call secure task design in this article, consists of two steps: high-level security policy design and low-level enforcement scheme design. A high-level security policy states an overall requirement for a sensitive task. One example of a high-level security policy is a separation of duty policy, which requires a task to be performed by a team of at least k users. Unlike low-level enforcement schemes such as security constraints in workflows, a separation of duty policy states a high-level requirement about the task without referring to individual steps in the task. While extremely important and widely used, separation of duty policies state only requirements on the number of users involved in the task and do not capture the requirements on these users' attributes. In this article, we introduce a novel algebra that enables the formal specification of high-level policies that combine requirements on users' attributes with requirements on the number of users motivated by separation of duty considerations. We give the syntax and semantics of the algebra and study algebraic properties of its operators. After that, we study potential mechanisms to enforce high-level policies specified in the algebra and a number of computational problems related to policy analysis and enforcement.
A Stochastic Model for Quantitative Security Analyses of Networked Systems

Traditional security analyses are often geared toward cryptographic primitives or protocols. Although such analyses are necessary, they cannot address a defender's need for insight into which aspects of a networked system having a significant impact on its security, and how to tune its configurations or parameters so as to improve security. This question is known to be notoriously difficult to answer, and the state of the art is that we know little about it. Toward ultimately addressing this question, this paper presents a stochastic model for quantifying security of networked systems. The resulting model captures two aspects of a networked system: (1) the strength of deployed security mechanisms such as intrusion detection systems and (2) the underlying vulnerability graph, which reflects how attacks may proceed. The resulting model brings the following insights: (1) How should a defender “tune” system configurations (e.g., network topology) so as to improve security? (2) How should a defender “tune” system parameters (e.g., by upgrading which security mechanisms) so as to improve security? (3) Under what conditions is the steady-state number of compromised entities of interest below a given threshold with a high probability? Simulation studies are conducted to confirm the analytic results, and to show the tightness of the bounds of certain important metric that cannot be resolved analytically.
X‐ray Crystallographic and First‐Principles Theoretical Studies of K2[TcOCl5] and UV/Vis Investigation of the [TcOCl5]2– and [TcOCl4]– Ions

Dipotassium pentachloridooxidotechnetate, K2[TcOCl5], has been isolated as green single crystals by the dissolution of (NH4)TcO4 in 12 M HCl at 0 °C and careful precipitation with KCl. The structure of this compound was determined by single-crystal X-ray diffraction analysis [a = 13.0815(9), b = 9.8982(6), c = 6.7623(4) A; V = 875.605 A3, orthorhombic, Pnma, Z = 4] and compared with the corresponding molybdenum and rhenium analogues. The structure of K2[TcOCl5] was also investigated by density functional theory, and the results are in agreement with the crystallographic data. The oscillator strengths of the electronic transitions in the C4v complex anions [TcOCl5]2– and [TcOCl4]– were also calculated by using time-dependent density functional theory and compared with the experimental UV/Vis spectra.
MAGNETIC FIELD GENERATION AND PARTICLE ENERGIZATION AT RELATIVISTIC SHEAR BOUNDARIES IN COLLISIONLESS ELECTRON-POSITRON PLASMAS

Using particle-in-cell simulations, we study the kinetic physics of relativistic shear flow in collisionless electron-positron (e+e–) plasmas. We find efficient magnetic field generation and particle energization at the shear boundary, driven by streaming instabilities across the shear interface and sustained by the shear flow. Nonthermal, anisotropic high-energy particles are accelerated across field lines to produce a power-law tail turning over just below the shear Lorentz factor. These results have important implications for the dissipation and radiation of jets in blazars and gamma-ray bursts.
Bondi Accretion in the Presence of Vorticity

The classical Bondi-Hoyle formula gives the accretion rate onto a point particle of a gas with a uniform density and velocity. However, the Bondi-Hoyle problem considers only gas with no net vorticity, while in a real astrophysical situation accreting gas invariably has at least a small amount of vorticity. We therefore consider the related case of accretion of gas with constant vorticity, for the cases of both small and large vorticity. We confirm the findings of earlier two-dimensional simulations that even a small amount of vorticity can substantially change both the accretion rate and the morphology of the gas flow lines. We show that in three dimensions the resulting flow field is nonaxisymmetric and time-dependent. The reduction in accretion rate is due to an accumulation of circulation near the accreting particle. Using a combination of simulations and analytic treatment, we provide an approximate formula for the accretion rate of gas onto a point particle as a function of the vorticity of the surrounding gas.
Economic objects as cultural objects: discourse on foreign investment in post-socialist Europe

Bringing together perspectives from economic sociology and cultural sociology, this paper proposes that because economic phenomena are imbued with meaning they can be studied as cultural objects. This approach includes first identifying the content of people's understanding of economic phenomena and then tracing out what is it that structures their interpretations. The paper applies the cultural objects analysis to the public debates surrounding foreign investment in post-socialist Slovenia. Actors interpret economic phenomena so they can provide justifications for the positions they adopt in public debates and assess possible strategies of action. The content analysis of newspaper texts shows that foreign globalization pressures are mostly framed in a binary relation to national interests. But because economic consequences are uncertain, the particular understandings of how foreign investment affects national interests are multiple, even contradictory. They are shaped by the social identities of actors and historical and macro-structural conditions of post-socialism that make salient different, often contradictory, institutional orders.
2,4,6-Trichlorophenylisonitrile and 2,4,6-trichlorobenzonitrile

The molecular structures of the title compounds, 2,4,6-tri­chloro­phenyl­iso­nitrile (IUPAC name: 2,4,6-tri­chloro­phenyl isocyanide), C7H2Cl3N, and 2,4,6-tri­chloro­benzo­nitrile, C7H2Cl3N, are normal. The two structures are not isomorphous, but do contain similar two-dimensional layers in which pairs of mol­ecules are held together by pairs of Cl⋯CN [3.245 (3) A] or Cl⋯NC [3.153 (2) A] interactions. The two-dimensional isomorphism is lost through different layer-stacking modes.
Theory of the quantum paraelectric-ferroelectric transition

A realistic theory of the quantum paraelectric-ferroelectric transition is presented, involving parameters determined from band calculations and a renormalization group treatment of critical fluctuations. The effects of reduced dimensionality and deviations from cubic symmetry are determined. Expressions for the pressure dependence of ${T}_{c}$ as well as p and T dependence of the specific heat are derived, and evaluated for realistic materials parameters for the systems ${\mathrm{BaTiO}}_{3}$ and ${\mathrm{PbTiO}}_{3}.$ In these materials the ferroelectric soft mode dispersion apparently exhibits a very strong cubic anisotropy, which affects results in an important, albeit quantitative, manner. A change in order parameter orientation from (100) to (111) is predicted as quantum criticality is approached.
The Interpretation of Quantum Mechanics: Many Worlds or Many Words?

As cutting-edge experiments display ever more extreme forms of non-classical behavior, the prevailing view on the interpretation of quantum mechanics appears to be gradually changing. A (highly unscientific) poll taken at the 1997 UMBC quantum mechanics workshop gave the once all-dominant Copenhagen interpretation less than half of the votes. The Many Worlds interpretation (MWI) scored second, comfortably a head of the Consistent Histories and Bohm interpretations. It is argued that since all the above-mentioned approaches to nonrelativistic quantum mechanics give identical cookbook prescriptions for how to calculate things in practice, practical-minded experimentalists, who have traditionally adopted the “shut-up-and-calculate interpretation”, typically show little interest in whether cozy classical concepts are in fact real in some untestable metaphysical sense or merely the way we subjectively perceive a mathematically simpler world where the Schrodinger equation describes everything – and that they are therefore becoming less bothered by a profusion of worlds than by a profusion of words. Common objections to the MWI are discussed. It is argued that when environment-induced decoherence is taken into account, the experimental predictions of the MWI are identical to those of the Copenhagen interpretation except for an experiment involving a Byzantine form of “quantum suicide”. This makes the choice between them purely a matter of taste, roughly equivalent to whether one believes mathematical language or human language to be more fundamental.
INVERSION OF ADJUNCTION FOR LOCAL COMPLETE INTERSECTION VARIETIES

We extend Inversion of Adjunction and Semicontinity of minimal log discrepancies from the case of a smooth ambient variety to the case of local complete intersection varieties.
Stochastic inflation and the equity premium

Abstract Stochastic inflation and the equity premium are studied in an asset-pricing endowment model with a cash-in-advance constraint. Inflation affects the equity premium through the inflation tax and the inflation risk premium. The equity premium in both the monetary model and the real model - a continuous state-space generalization of Mehra and Prescott (1985) - is sensitive to the conditional variance of the endowment growth. When the standard deviation is increased from 3.49% to 5.59%, the real model generates an equity premium of 2.8% in the relevant range of risk aversion parameters; the monetary model generates an equity premium of 5.81%.