cssi/SciSciGPT-SciSciNet huggingface dataset:
Optimum positioning of interleaved repeaters in bidirectional buses

It is shown in this paper that the optimum position of interleaved repeaters for minimum delay and noise is not the midpoint as commonly practiced. A closed-form solution for the optimum position has been derived in this paper and verified by simulation. Bidirectional buses with the optimum interleaved repeater position are compared to commonly used bidirectional buses and shown to provide an improvement greater than 50% in the propagation delay and bit-rate per unit area. The area of the induced noise pulse on victim lines is shown to be zero indicating that the aggressor lines are virtually static with the optimum repeater position. The presented optimum repeater positioning also provides lower noise pulse amplitude as well as lower sensitivity of propagation delay and noise pulse peak to segment length variation, compared to commonly used midway repeater positioning.
Wealth and Risk Effects of Adopting Deposit Insurance in Canada: Evidence of Risk Shifting by Banks and Trust Companies

This paper confirms that adopting explicit deposit insurance expanded risk-shifting incentives for Canadian Banks and Trust Companies. By transferring responsibility for monitoring non-systematic risk to the Canadian Deposit Insurance Corporation (CDIC), deposit insurance eliminated the compensation previously paid to large-block stockholder monitors. This transfer fueled a redistribution of insured-institution stock from poorly diversified large-block shareholders to diversified investors. Also, subsequent changes in market volatility support the hypothesis that CDIC insurance and the absorption of catastrophic risk it provided reduced systematic risk in the stock market as a whole even as it increased non-systematic risk in the banking and trust-company sector.
Formal aminocyanation of α,β-unsaturated cyclic enones for the efficient synthesis of α-amino ketones.

Installation of amino functionality on organic molecules through direct CN bond formation is an important research objective. To achieve this goal, a 1,2-aminocyanation reaction was developed. The reaction occurs through the formation of pyrazolines by means of a formal dipolar cycloaddition of cyclic α,β-unsaturated ketones with lithium trimethylsilyldiazomethane followed by novel protonolytic NN bond cleavage under mild conditions. This two-step process provides a diverse array of structurally complex free and mono-alkylated α-amino ketones in excellent yields.
Supersymmetric Janus solutions in five and ten dimensions

We explicitly truncate $ \mathcal{N} = 8 $ gauged supergravity in five dimensions to its SU(3)-invariant sector with dilaton and axion fields. We show that this truncation has a solution which is identical to the super Janus constructed in $ \mathcal{N} = 2 $ gauged supergravity in five dimensions. Then we lift the solution of the SU(3)-invariant truncation to type IIB supergravity by employing the consistent truncation ansatz. We show that the lifted solution falls into a special case of the supersymmetric Janus solutions constructed in type IIB supergravity. Additionally, we also prove that the lifted solution provides a particular example of the consistent truncations of type IIB supergravity on Sasaki-Einstein manifolds.
Photochemistry of 2-azidoadenine in alcohols

Abstract Photolysis of 2-azidoadenine in methanol (ethanol) gives 2,6-diaminopurine plus 8-methoxy(ethoxy)-2,6-diaminopurine.
SNEED: Enhancing Network Security Services Using Network Coding and Joint Capacity

Traditional network security protocols depend mainly on developing cryptographic schemes and on using biometric methods. These have led to several network security protocols that are unbreakable based on difficulty of solving untractable mathematical problems such as factoring large integers. In this paper, \emph{{\underline{S}ecurity of \underline{N}etworks \underline{E}mploying \underline{E}ncoding and \underline{D}ecoding}} (\textbf{SNEED}) is developed to mitigate single and multiple link attacks. Network coding and shared capacity among the working paths are used to provide data protection and data integrity against network attackers and eavesdroppers. \textbf{SNEED} can be incorporated into various applications in on-demand TV, satellite communications and multimedia security. Finally, It is shown that \textbf{SNEED} can be implemented easily where there are $k$ edge disjoint paths between two core nodes (routers or switches) in an enterprize network.
The Worst Page-Replacement Policy

In this paper, we consider the following question: what is the worst possible page-replacement strategy? Our goal is to devise an online strategy that has the highest possible fraction of page faults as compared to the worst offline strategy. We show that there is no deterministic, online page-replacement strategy that is competitive with the worst offline strategy. We give a randomized strategy based on the “most-recently-used” heuristic and show that this strategy is the worst possible online page-replacement strategy.
Simplicial matrix-tree theorems

First published in Transactions of the American Mathematical Society in volume 361 (2009), no. 11, 6073--6114, published by the American Mathematical Society
Preferential induction of protective T cell responses to Theiler's virus in resistant (C57BL/6 x SJL)F1 mice.

Infection of the central nervous system (CNS) with Theiler’s murine encephalomyelitis virus (TMEV) induces an immune-mediated demyelinating disease in susceptible mouse strains such as SJL/J (H-2 s ) but not in strains such as C57BL/6 (H-2 b ). In addition, it has been shown that (C57BL/6 SJL/J)F1 mice (F1 mice), which carry both resistant and susceptible MHC haplotypes (H-2 b/s ), are resistant to both viral persistence and TMEV-induced demyelinating disease. In this study, we further analyzed the immune responses underlying the resistance of F1 mice. Our study shows that the resistance of F1 mice is associated with a higher level of the initial virus-specific H-2 b -restricted CD8 T cell responses than of the H-2 s -restricted CD8 T cell responses. In contrast, pathogenic Th17 responses to viral epitopes are lower in F1 mice than in susceptible SJL/J mice. Dominant effects of resistant genes expressed in antigen-presenting cells of F1 mice on regulation of viral replication and induction of protective T cell responses appear to play a crucial role in disease resistance. Although the F1 mice are resistant to disease, the level of viral RNA in the CNS was intermediate between those of SJL/J and C57BL/6 mice, indicating the presence of a threshold of viral expression for pathogenesis. Intracerebral infection of susceptible mice with Theiler’s murine encephalomyelitis virus (TMEV) induces a chronic, progressive demyelinating disease that is clinically and histopathologically similar to a form of human multiple sclerosis (MS) (25). In addition, the various immunological and genetic factors that affect disease outcome in TMEV-infected mice closely parallel those associated with the development of MS (23). Combined with a suspected viral etiology for MS (1, 13, 46), these similarities make TMEV-induced demyelinating disease (TMEV-IDD) an attractive and relevant infectious model for investigating this human demyelinating disease. Development of TMEV-IDD in highly susceptible SJL/J (H-2 s ) mice (SJL mice) is associated with chronic viral persistence in the central nervous system (CNS) (7, 26, 44), whereas resistant C57BL/6 (H-2 b ) mice (B6 mice) clear the virus within
Accuracy of ECG interpretation in the pediatric emergency department.

Study objective We assess accuracy of ECG interpretation and indications for obtaining ECGs and develop a clinical classification system of ECG abnormalities. Methods Prospectively acquired ECG data on patients 0 to 21 years of age and presenting to our pediatric emergency department (ED) were obtained. Clinical indications were documented. The initial ECG interpretation (pediatric ED attending physician) was compared with the criterion standard (pediatric cardiologist). A blinded cardiology panel reviewed discrepancies, and a final concordance rate was determined. An ECG abnormality classification system was developed and used to categorize these abnormal ECGs. Results One thousand six hundred fifty-three ECGs from 1,501 patients, aged 2 days to 21 years (median 10.0 years), were obtained during 3.5 years. Fifty-one percent were male patients. ECG indications included chest pain (21%), seizure or syncope (18%), arrhythmias (17%), apparent life-threatening event or respiratory symptoms (16%), ingestions (10%), cardiac abnormality (10%), and miscellaneous (8%). From 1,631 ECGs, 1,160 (71%) were normal (class 0), 259 (16%) were minimally abnormal (class I), 174 (11%) were moderately abnormal (class II), and 38 (2%) were severely abnormal (class III). Kendall's τ-b test showed concordance of 0.73 (95% confidence interval 0.70 to 0.77) between pediatric ED and cardiology interpretation. The sensitivity of pediatric ED interpretation was 75%, and the specificity was 98.5%. The positive predictive value of pediatric ED interpretation was 88.3%, and the negative predictive value was 96.3%. Conclusion We conclude that, overall, a high rate of concordance exists between the pediatric emergency physician's and the cardiologist's ECG interpretation. The majority of discordant ECGs are not clinically significant. However, among the clinically significant ECGs, there is a higher rate of discordance. These data suggest that review of pediatric ECGs by pediatric cardiologists may significantly reduce underdetection of clinically important ECG findings in children.
Stereochemical memory effects in alkene radical cation/anion contact ion pairs: effect of substituents, and models for diastereoselectivity.

A series of 12 stereochemically defined 2,m-dimethyl- and 2,m,n-trimethyl-6-benzylamino-2-nitro-3-(diphenylphosphatoxy)hexanes have been synthesized and their cyclization reactions leading to di- and trisubstituted N-benzyl pyrrolidines examined in the presence of tributyltin hydride and azoisobutyronitrile in benzene at reflux. The cyclizations are interpreted in terms of generation of an alkyl radical by abstraction of the nitro group with a stannyl radical. The phosphate leaving group is then expelled in a heterolytic cleavage to give a contact alkene radical cation/phosphate anion pair. For the majority of the examples studied, the cyclizations are best understood in terms of nucleophilic attack by the amine on the opposite face of the alkene radical cation to the one shielded by the leaving group, within the confines of the initial contact ion pair, resulting in overall cyclization with inversion of configuration. Dependent on the relative stereochemistry of the substituents, the cyclization is envis...
Synthesis of indolocarbazoles via sequential palladium catalyzed cross-coupling and benzannulation reactions

Abstract Differentially substituted indolocarbazoles are readily prepared via a synthetic route employing two palladium catalyzed reactions. First, biindoles are prepared from a palladium catalyzed cross coupling reaction. Second, a new palladium catalyzed benzannulation reaction employing biindolyl iodides and alkynes provides indolocarbazoles.
The incidental parameter problem since 1948

This paper was written to mark the 50th anniversary of Neyman and Scott's Econometrica paper defining the incidental parameter problem. It surveys the history both of the paper and of the problem in the statistics and econometrics literature.
Coherence and polarization properties of electromagnetic laser modes

Abstract A recently formulated mode representation of stochastic electromagnetic fields, based on a unified theory of coherence and polarization is applied to determine the transverse laser resonator modes in any rotationally symmetric cavity. It is found that the electromagnetic modes can be expressed in a simple way in terms of the classic Fox–Li modes of the monochromatic scalar theory; and that, if there is no degeneracy, each mode is completely spatially coherent and its degree of polarization is the same at each point of the cavity mirror.
General optimization technique for high-quality community detection in complex networks.

networks. Most of them are based upon the optimization of objective functions, among which modularity is the most common, though a number of alternatives have been suggested in the scientific literature. We present here an effective general search strategy for the optimization of various objective functions for community detection purposes. When applied to modularity, on both real-world and synthetic networks, our search strategy substantially outperforms the best existing algorithms in terms of final scores of the objective function. In terms of execution time for modularity optimization this approach also outperforms most of the alternatives present in literature with the exception of fastest but usually less efficient greedy algorithms. The networks of up to 30000 nodes can be analyzed in time spans ranging from minutes to a few hours on average workstations, making our approach readily applicable to tasks not limited by strict time constraints but requiring the quality of partitioning to be as high as possible. Some examples are presented in order to demonstrate how this quality could be affected by even relatively small changes in the modularity score stressing the importance of optimization accuracy.
The Coincidence of Nuclear Star Clusters and Active Galactic Nuclei

We study galaxies that host both nuclear star clusters and AGNs, implying the presence of a massive black hole. We select a sample of 176 galaxies with previously detected nuclear star clusters that range from ellipticals to late-type spirals. We search for AGNs in this sample using optical spectroscopy and archival radio and X-ray data. We find galaxies of all Hubble types and with a wide range of masses (109-1011 M☉) hosting both AGNs and nuclear star clusters. From the optical spectra, we classify 10% of the galaxies as AGN and an additional 15% as composite, indicating a mix of AGN and star formation spectra. The fraction of nucleated galaxies with AGNs increases strongly as a function of galaxy and nuclear star cluster mass. For galaxies with both a nuclear star cluster and a black hole, we find that the masses of these two objects are quite similar. However, nondetections of black holes in Local Group nuclear star clusters show that not all clusters host black holes of similar masses. We discuss the implications of our results for the formation of nuclear star clusters and massive black holes.
The eccentric frame decomposition of central force fields

The rosette-shaped motion of a particle in a central force field is known to be classically solvable by quadratures. We present a new approach of describing and characterizing such motion based on the eccentricity vector of the two body problem. In general, this vector is not an integral of motion. However, the orbital motion, when viewed from the nonuniformly rotating frame defined by the orientation of the eccentricity vector, can be solved analytically and will either be a closed periodic circulation or libration. The motion with respect to inertial space is then given by integrating the argument of periapsis with respect to time. Finally we will apply the decomposition to a modern central potential, the spherical Hernquist–Newton potential, which models dark matter halos of galaxies with central black holes.
List-decoding using the XOR lemma

We show that Yao's XOR Lemma, and its essentially equivalent rephrasing as a Direct Product Lemma, can be re-interpreted as a way of obtaining error-correcting codes with good list-decoding algorithms from error-correcting codes having weak unique-decoding algorithms. To get codes with good rate and efficient list decoding algorithms, one needs a proof of the Direct Product Lemma that, respectively, is strongly derandomized, and uses very small advice. We show how to reduce advice in Impagliazzo's proof of the Direct Product Lemma for pairwise independent inputs, which leads to error-correcting codes with O(n/sup 2/) encoding length, 0/sup /spl tilde//(n/sup 2/) encoding time, and probabilistic 0/sup /spl tilde//(n) list-decoding time. (Note that the decoding time is sub-linear in the length of the encoding.) Back to complexity theory, our advice-efficient proof of Impagliazzo's hard-core set results yields a (weak) uniform version of O'Donnell results on amplification of hardness in NP. We show that if there is a problem in NP that cannot be solved by BPP algorithms on more than a 1 - 1/(log n)/sup c/ fraction of inputs, then there is a problem in NP that cannot be solved by BPP algorithms on more than a 3/4 + 1/(log n)/sup c/ fraction of inputs, where c > 0 is an absolute constant.
IMPROVED CONSTRAINTS ON THE PREFERENTIAL HEATING AND ACCELERATION OF OXYGEN IONS IN THE EXTENDED SOLAR CORONA

We present a detailed analysis of oxygen ion velocity distributions in the extended solar corona, based on observations made with the Ultraviolet Coronagraph Spectrometer (UVCS) on the SOHO spacecraft. Polar coronal holes exhibit broad line widths and unusual intensity ratios of the O VI λλ1032, 1037 emission-line doublet. A traditional interpretation of these features is that oxygen ions have a strong temperature anisotropy, with the temperature perpendicular to the magnetic field being much larger than the temperature parallel to the field. However, recent work by Raouafi and Solanki suggested it may be possible to model the observations using an isotropic velocity distribution. In this paper we analyze an expanded data set to show that the original interpretation of an anisotropic distribution is the only one fully consistent with the observations. It is necessary to search the full range of ion plasma parameters to determine the values with the highest probability of agreement with the UVCS data. The derived ion outflow speeds and perpendicular kinetic temperatures are consistent with earlier results, and there continues to be strong evidence for preferential ion heating and acceleration with respect to hydrogen. At heliocentric heights above 2.1 solar radii, every UVCS data point is more consistent with an anisotropic distribution than with an isotropic distribution. At heights above 3 solar radii, the exact probability of isotropy depends on the electron density chosen to simulate the line-of-sight distribution of O VI emissivity. The most realistic electron densities (which decrease steeply from 3 to 6 solar radii) produce the lowest probabilities of isotropy and most probable temperature anisotropy ratios that exceed 10.
Exorcising the Ghost of Cigarette Advertising Past: Collusion, Regulation, and Fear Advertising

Cigarette advertising from 1952 through 1954 that made remarkable claims of protection for the smoker’s health were in part responsible for unprecedented declines in per capita cigarette consumption in 1953 and 1954. It has long been held that the Federal Trade Commission (FTC) brought this competitive episode to a sudden halt by circulating a draft set of Cigarette Advertising Guides and subsequently enforcing those guidelines. Using a combination of documentary evidence and an analysis of cigarette advertising content, the author shows here that it was collusion on the part of the tobacco industry and not the actions of the FTC that brought the fear advertising of the early 1950s to an abrupt end.
Nonideal battery and main memory effects on CPU speed-setting for low power

This paper explores the system-level power-performance tradeoffs of dynamically varying CPU speed. Previous work in CPU speed-setting considered only the power of the CPU and only CPUs that vary supply voltage with frequency. This work takes a broader approach, considering total system power, battery capacity, and main memory bandwidth. The results, which are up to a factor of four less than ideal, show that all three must be considered when setting the CPU speed.
Multimerization of Tegument Protein pp28 within the Assembly Compartment Is Required for Cytoplasmic Envelopment of Human Cytomegalovirus

Human cytomegalovirus (HCMV) UL99-encoded pp28 is an essential tegument protein required for envelopment and production of infectious virus. Nonenveloped virions accumulate in the cytoplasm of cells infected with recombinant viruses with the UL99 gene deleted. Previous results have suggested that a key function of pp28 in the envelopment of infectious HCMV is expressed after the protein localizes in the assembly compartment (AC). In this study, we investigated the potential role of pp28 multimerization in the envelopment of the infectious virion. Our results indicated that pp28 multimerized during viral infection and that interacting domains responsible for self-interaction were localized in the amino terminus of the protein (amino acids [aa] 1 to 43). The results from transient-expression and/or infection assays indicated that the self-interaction took place in the AC. A mutant pp28 molecule containing only the first 35 aa failed to accumulate in the AC, did not interact with pp28 in the AC, and could not support virus replication. In contrast, the first 50 aa of pp28 was sufficient for the self-interaction within the AC and the assembly of infectious virus. Recombinant viruses encoding an in-frame deletion of aa 26 to 33 of pp28 were replication competent, whereas infectious virus was not recovered from HCMV BACs lacking aa 26 to 43. These findings suggested that the accumulation of pp28 was a prerequisite for multimerization of pp28 within the AC and that pp28 multimerization in the AC represented an essential step in the envelopment and production of infectious virions.
Structure and Magnetic Ordering of the Anomalous Layered (2D) Ferrimagnet [NEt4]2MnII3(CN)8 and 3D Bridged‐Layered Antiferromagnet [NEt4]MnII3(CN)7 Prussian Blue Analogues

The reaction of Mn(II) and [NEt(4)]CN leads to the isolation of solvated [NEt(4)]Mn(3)(CN)(7) (1) and [NEt(4)](2) Mn(3)(CN)(8) (2), which have hexagonal unit cells [1: R3m, a = 8.0738(1), c = 29.086(1) A; 2: P3m1, a = 7.9992(3), c = 14.014(1) A] rather than the face centered cubic lattice that is typical of Prussian blue structured materials. The formula units of both 1 and 2 are composed of one low- and two high-spin Mn(II) ions. Each low-spin, octahedral [Mn(II)(CN)(6)](4-) bonds to six high-spin tetrahedral Mn(II) ions through the N atoms, and each of the tetrahedral Mn(II) ions are bound to three low-spin octahedral [Mn(II)(CN)(6)](4-) moieties. For 2, the fourth cyanide on the tetrahedral Mn(II) site is C bound and is terminal. In contrast, it is orientationally disordered and bridges two tetrahedral Mn(II) centers for 1 forming an extended 3D network structure. The layers of octahedra are separated by 14.01 A (c axis) for 2, and 9.70 A (c/3) for 1. The [NEt(4)](+) cations and solvent are disordered and reside between the layers. Both 1 and 2 possess antiferromagnetic superexchange coupling between each low-spin (S = 1/2) octahedral Mn(II) site and two high-spin (S = 5/2) tetrahedral Mn(II) sites within a layer. Analogue 2 orders as a ferrimagnet at 27(±1) K with a coercive field and remanent magnetization of 1140 Oe and 22,800 emuOe mol(-1), respectively, and the magnetization approaches saturation of 49,800 emuOe mol(-1) at 90,000 Oe. In contrast, the bonding via bridging cyanides between the ferrimagnetic layers leads to antiferromagnetic coupling, and 3D structured 1 has a different magnetic behavior to 2. Thus, 1 is a Prussian blue analogue with an antiferromagnetic ground state [T(c) = 27 K from d(χT)/dT].
Adventures in Carbohydrate Chemistry: New Synthetic Technologies, Chemical Synthesis, Molecular Design, and Chemical Biology

The field of carbohydrate chemistry has occupied the minds and hearts of many scientists for over a hundred years and, as we enter the twenty-first century, it continues to be both vigorous and challenging. Among the most exciting aspects of organic chemistry in the last few decades has been the interplay between the specialized subdisciplines of carbohydrate chemistry and total synthesis, each enabling and advancing the other in new directions and towards greater heights. In this review article we highlight our own adventures at the interface of these disciplines, which were driven for the most part by objectives in chemical synthesis and chemical biology. Specifically, we describe our interests and efforts to utilize carbohydrates as starting materials for total synthesis, to invent and develop new synthetic technologies for carbohydrate synthesis, to construct complex oligosaccharides in solution or on solid support, and to utilize carbohydrate templates as scaffolds for peptide mimetics and for molecular diversity construction. Finally, applications of the developed synthetic strategies and enabling technologies towards the solution of biologically significant problems are discussed.
Minimally Invasive Total Knee Arthroplasty with an Optimized Subvastus Approach

The minimally invasive surgery subvastus approach provides very good exposure through a small incision, preserves all 4 attachments of the quadriceps to the patella, does not require patella eversion, minimizes disruption in the suprapatellar pouch, and allows rapid and reliable closure of the knee. The patella and entire distal portion of the extensor mechanism can be retracted into the lateral gutter of the knee where they remain out of the way and allow direct visualization of both femoral condyles. When coupled with instruments designed specifically for small incision surgery, the modified subvastus approach is reliable, reproducible, and safe. Using a simple set of retractors the surgeon can perform the surgery without making any blind cuts or freehand cuts and that enhances surgical accuracy and patient safety.
THEMIS characterization of the MER Gusev crater landing site

[1] Gusev crater, previously interpreted as the depocenter for the Gusev-Ma'adim Vallis fluvio-lacustrine system, is a proposed landing site for one of the Mars Exploration Rovers (MER). Here we use new remote-sensing data from the Thermal Emission Imaging System (THEMIS) supplemented by data from the Thermal Emission Spectrometer (TES), Mars Orbiter Camera (MOC), and Mars Orbiter Laser Altimeter (MOLA) to characterize the geology of Gusev crater. Thermal infrared data from THEMIS and TES were used to map thermophysical units on the basis of relative albedos and diurnal temperature variations. THEMIS and MOC visible images were used to map unit morphologies and to estimate crater density ages. MOLA data were used to identify unit contacts and stratigraphic relationships. Various data were then combined to construct a new surface unit map and stratigraphy for units on the floor of Gusev. Seven surface units were identified in Gusev, mostly Hesperian in age, but with two showing evidence of later modification and redistribution. Five or more surface units and layering are present within the MER-A landing ellipse, attesting to the geologic diversity of this site. Surface units show features that could be consistent with fluvio-lacustrine, aeolian, and/or volcanoclastic deposition, but the spatial resolution of visible/infrared data does not allow for the identification of unambiguous volcanic or fluvio-lacustrine textures. However, a MER landing in Gusev may provide the opportunity to analyze multiple units, distinguish rock types, examine stratigraphic relationships, and shed light on the ancient depositional environment.
New Measurements of Upsilon Spin Alignment at the Tevatron

We describe a new analysis of {Upsilon}(nS) {yields} {mu}{sup +}{mu}{sup -} decays collected in p{bar p} collisions with the CDF II detector at the Fermilab Tevatron. This analysis measures the angular distributions of the final state muons in the {Upsilon} rest frame, providing new information about {Upsilon} production polarization. We find the angular distributions to be nearly isotropic up to {Upsilon} p{sub T} of 40 GeV/c, consistent with previous measurements by CDF, but inconsistent with results obtained by the D0 experiment. The results are compared with recent NLO calculations based on color-singlet matrix elements and non-relativistic QCD with color-octet matrix elements.
N-iodosuccinimide mediated oxidative cleavage of vicinal, monoprotected diols

Abstract Vicinal, monoprotected diols are cleaved to mixed acetals and carbonyl compounds upon treatment with N-iodosuccinimide in the presence of light, base, and methanol.
Uniqueness of User Equilibrium in Transportation Networks with Heterogeneous Commuters

This paper discusses the uniqueness of user equilibrium in transportation networks with heterogeneous commuters. Daganzo (1983) proved the uniqueness of (stochastic) user equilibrium when commuters have heterogeneous tastes over possible paths, but identical disutility functions from time costs. We first show, by example, that his result may not apply in general networks if disutility functions are allowed to differ. However, for "simple" transportation networks, we show that user equilibrium is always unique and weakly Pareto efficient (cf. the Braess example) for a general class of utility functions. We investigate whether this result applies to more general networks. We also show that user equilibrium is unique in a dynamic bottleneck model with a simple network. We discuss an interesting relationship between the following two problems: the existence of user equilibrium in a finite model and the uniqueness of user equilibrium in a continuum model. In the appendix, we also provide a proof of a slightly generalized version of Daganzo's theorem.
A new restoring algorithm for the preferential enhancement of edge gradients

We present here a new restoring algorithm that is based on use of a “median-window filter.” This is intrinsically a nonlinear operation that, when cyclically used with any linear restoring algorithm, can typically enhance edge gradients by a factor of 5:1 with nearly a complete absence of Gibbs oscillation.
Studies on magnet shuffling for RHIC

Shuffling of arc dipoles is performed on realistic RHIC (Relativistic Heavy Ion Collider) lattices; Delta beta / beta , Delta X/sub p// square root beta /sub x/, and Y/sub p// square root beta /sub y/ from random a1 and b1 multipoles are reduced to acceptable levels. Even before shuffling, the contribution from the arc dipoles is less than the contribution from the insertion magnets. In the insertions, the contribution from the random b1s is removed by the independent powering of all insertion quadrupoles; the contribution of random a1s to coupling will be corrected with skew quadrupole correction elements. >
Effects of Radiation Forces on the Frequency of Gravitomagnetic Precession near Neutron Stars

Gravitomagnetic precession near neutron stars and black holes has received much recent attention, particularly as a possible explanation of 15-60 Hz quasi-periodic brightness oscillations (QPOs) from accreting neutron stars in low-mass X-ray binaries, and of somewhat higher frequency QPOs from accreting stellar-mass black holes. Previous analyses of this phenomenon have either ignored radiation forces or assumed for simplicity that the radiation field is isotropic, and in particular that there is no variation of the radiation field with angular distance from the rotational equatorial plane of the compact object. However, in most realistic accretion geometries (e.g., those in which the accretion proceeds via a geometrically thin disk) the radiation field depends on latitude. Here we show that in this case radiation forces typically have an important, even dominant, effect on the precession frequency of test particles in orbits that are tilted with respect to the star's rotational equator. Indeed, we find that even for accretion luminosities only a few percent of the Eddington critical luminosity, the precession frequency near a neutron star can be changed by factors of up to ~10. Radiation forces must therefore be included in analyses of precession frequencies near compact objects in such varied contexts as low-frequency QPOs, warp modes of disks, and trapped oscillation modes. We discuss specifically the impact of radiation forces on models of low-frequency QPOs involving gravitomagnetic precession, and we show that such models are rendered much less plausible by the effects of radiation forces.
Evaluation of Gamma Cameras for Use in Dedicated Breast Imaging

Due to the limitations of conventional gamma cameras for breast imaging, many researchers are developing dedicated imagers for use in scintimammography that can be positioned closer to the breast, thereby improving spatial resolution. The purpose of this paper was to compare the performance characteristics of several dedicated gamma cameras with two different types of position sensitive photomultiplier tubes (PSPMTs), and four different NaI crystal arrays. Quantities evaluated include intrinsic spatial resolution, spatial resolution versus source-to-crystal distance, energy resolution, intrinsic nonuniformity, and system sensitivity. In order to assess the impact of changing crystal size on lesion detectability, a contrast-detail study was also performed. Our studies demonstrate that the camera with the newer PSPMTs (Hamamatsu model H8500) shows superior performance in terms of uniformity and energy resolution. The contrast-detail performance of the camera with the highest spatial resolution (1.4-mm crystal pitch with a high resolution collimator) was poor, even with relatively high input fluence. However, the use of a high-efficiency collimator significantly improves object detectability. The camera with the largest (3.2 mm) crystal pitch performed better than the others tested, with both high resolution and high efficiency collimators. However, its performance for small lesion size was better with the high-resolution collimator. Hence, based on the results of the contrast-detail study, of the cameras evaluated here, the camera with the 3.2-mm crystal pitch and the high-resolution collimator is best suited for imaging breast tumors
Palladium‐Catalyzed Glycosylation Reaction: De‐Novo Synthesis of Trehalose Analogues

The unnatural L‐1,1‐α‐disaccharides were synthesized from acylfurans using a palladium‐catalyzed glycosylation reaction. The 1,1‐α‐manno‐disaccharides were achieved in six total steps starting from an acylfuran. The overall efficiency of this protocol was the use of highly diastereoselective palladium‐catalyzed glycosylation, reduction, and dihydroxylation. This paper is dedicated to Prof. Denis W. H. MacDowell during the year of his 80th birthday.
AVERAGE-CASE SCALABILITY ANALYSIS OF PARALLEL COMPUTATIONS ON k-ARY d-CUBES

We investigate the average-case scalability of parallel algorithms executing on multicomputer systems whose static networks are k-ary d-cubes. Our performance metrics are isoefficiency function and...
TEMPORALLY-PERIODIC STATES OF EXTENDED NONEQUILIBRIUM SYSTEMS

We summarize recent results concerning the stability of spatially‐coherent, time‐periodic states in noisy, classical, discrete‐time, many‐body systems with short‐range interactions. Generic stability of periodic k‐cycles with k≳2 can be achieved only by rules carefully constructed to exploit lattice anisotropy and so suppress droplet growth. For ordinary rules which do not utilize spatial anisotropy in this way, periodic k‐cycles with periods k≳2 are metastable rather than stable under generic conditions, losing spatial coherence through nucleation and growth of droplets.
Who Pays a Price on Carbon

We use the 2003 Consumer Expenditure Survey and emissions estimates from an input-output model based on the 1997 US economy to estimate the incidence of a price on carbon induced by a cap-and-trade program or carbon tax in the context of the US. We present results on how much different income deciles pay for a carbon tax as well as which industries see the largest increase in costs due to a carbon tax. We illustrate the main determinant of the regressivity: consumption patterns for energy-intensive goods. Furthermore, on a per-capita basis a carbon price is much more regressive than calculations at the household level. We discuss policy options to offset the adverse distributional effects of a carbon emissions policy.
A Dynamic Near-Optimal Algorithm for Online Linear Programming

A natural optimization model that formulates many online resource allocation problems is the online linear programming LP problem in which the constraint matrix is revealed column by column along with the corresponding objective coefficient. In such a model, a decision variable has to be set each time a column is revealed without observing the future inputs, and the goal is to maximize the overall objective function. In this paper, we propose a near-optimal algorithm for this general class of online problems under the assumptions of random order of arrival and some mild conditions on the size of the LP right-hand-side input. Specifically, our learning-based algorithm works by dynamically updating a threshold price vector at geometric time intervals, where the dual prices learned from the revealed columns in the previous period are used to determine the sequential decisions in the current period. Through dynamic learning, the competitiveness of our algorithm improves over the past study of the same problem. We also present a worst case example showing that the performance of our algorithm is near optimal.
Enantioselective Total Synthesis of the Nonisoprenoid Sesquiterpene (−)‐Kumausallene

An acyl radical cyclization to form the bicyclic core of (-)-kumausallene (1) was the key feature in the 14-step, enantioselective synthesis. This work demonstrates that the bromoallene unit is robust enough to withstand multiple synthetic operations and provides the unambiguous assignment of the absolute configuration of the bromoallene.
Improved Catalysts for the Palladium-Catalyzed Synthesis of Oxindoles by Amide α-Arylation. Rate Acceleration, Use of Aryl Chloride Substrates, and a New Carbene Ligand for Asymmetric Transformations

Catalysts comprised Pd(OAc)2 and either PCy3 or sterically hindered N-heterocyclic carbene ligands provide fast rates for a palladium-catalyzed synthesis of oxindoles by amide α-arylation. This catalyst system allowed for room-temperature reactions in some cases and reactions of aryl chlorides at 70 °C. Most important, reactions occurred in high yields under mild conditions to form the quaternary carbon in α,α-disubstituted oxindoles. The combined inter- and intramolecular reaction afforded an efficient synthetic method for formation of α-aryloxindole derivatives. Surprisingly, catalysts containing tert-butylphosphine ligands, which have been most reactive for ketone arylations, were less active than those containing PCy3. Use of new, optically active heterocyclic carbene ligands gave substantial enantioselectivity in formation of an α,α-disubstituted oxindole. In contrast, a variety of optically active phosphine ligands that were tested gave poor enantioselectivity. Mechanistic studies showed that the re...
Reactions in Droplets in Microfluidic Channels

Fundamental and applied research in chemistry and biology benefits from opportunities provided by droplet-based microfluidic systems. These systems enable the miniaturization of reactions by compartmentalizing reactions in droplets of femoliter to microliter volumes. Compartmentalization in droplets provides rapid mixing of reagents, control of the timing of reactions on timescales from milliseconds to months, control of interfacial properties, and the ability to synthesize and transport solid reagents and products. Droplet-based microfluidics can help to enhance and accelerate chemical and biochemical screening, protein crystallization, enzymatic kinetics, and assays. Moreover, the control provided by droplets in microfluidic devices can lead to new scientific methods and insights.
NON-UNIFORM "FAT-MESHES" FOR CHIP MULTIPROCESSORS

This paper studies the traffic hot spots of mesh networks in the context of chip multiprocessors. To mitigate these effects, this paper describes a non-uniform fat-mesh extension to mesh networks, which are popular for chip multiprocessors. The fat-mesh is inspired by the fat-tree and dedicates additional links for connections with heavy traffic (e.g. near the center) with fewer links for lighter traffic (e.g. near the periphery). Two fat-mesh schemes are studied based on the traffic requirements of chip multiprocessors using dimensional ordered XY routing and a randomized XY-YX routing algorithms, respectively. Analytical fat-mesh models are constructed by theoretically presenting the expressions for the traffic requirements of personalized all-to-all traffic for both the raw message numbers and their normalized equivalents. We demonstrate how traffic scales for a traditional mesh compared to a non-uniform fat mesh. Simulation results demonstrate that using same number of physical links the non-uniform fat-mesh can achieve better performance than a uniform fat-mesh mesh using both synthetic traffic patterns and splash-2 benchmark traces.
DSP control of high-power UPS systems feeding nonlinear loads

Many facilities, such as patient health care centers, data processing systems, and critical telecommunication links, rely on uninterruptible power supplies (UPS) to maintain a continuous supply of power in case of a line outage. In addition to requiring continuous power, many critical nonlinear loads are sensitive to incoming line transients and input harmonic voltage distortion. Conventional UPS systems operate to protect against such disturbances using complex filtering schemes, often employing large passive components. This paper presents the advantages of using real time digital signal processing (DSP) control of UPS systems. A DSP controlled UPS inverter and harmonic conditioning system is described and the performance is verified on a 150 kVA system.
Labor market assimilation and the self-employment decision of immigrant entrepreneurs

This paper uses data from the 1980 and 1990 U.S. Censuses to study labor market assimilation of self-employed immigrants. Separate earnings functions for the self-employed and wage/salary workers are estimated. To control for endogenous sorting into the sectors, models of the self-employment decision are estimated. Self-employed immigrants are found to do substantially better in the labor market than wage/salary immigrants. Earnings of self-employed immigrants are predicted to converge with natives' wage/salary earnings at about age 30 and natives' self-employed earnings at about age 40. Including the self-employed in the sample reduces the immigrant-native earnings gap by, on average, 14%.
Chemical heterogeneity on Mercury's surface revealed by the MESSENGER X-Ray Spectrometer

[1] We present the analysis of 205 spatially resolved measurements of the surface composition of Mercury from MESSENGER’s X-Ray Spectrometer. The surface footprints of these measurements are categorized according to geological terrain. Northern smooth plains deposits and the plains interior to the Caloris basin differ compositionally from older terrain on Mercury. The older terrain generally has higher Mg/Si, S/Si, and Ca/Si ratios, and a lower Al/Si ratio than the smooth plains. Mercury’s surface mineralogy is likely dominated by high-Mg mafic minerals (e.g., enstatite), plagioclase feldspar, and lesser amounts of Ca, Mg, and/or Fe sulfides (e.g., oldhamite). The compositional difference between the volcanic smooth plains and the older terrain reflects different abundances of these minerals and points to the crystallization of the smooth plains from a more chemically evolved magma source. High-degree partial melts of enstatite chondrite material provide a generally good compositional and mineralogical match for much of the surface of Mercury. An exception is Fe, for which the low surface abundance on Mercury is still higher than that of melts from enstatite chondrites and may indicate an exogenous contribution from meteoroid impacts.
Photonic crystal laser-driven accelerator structures

We discuss simulated photonic crystal structure designs for laser-driven particle acceleration, focusing on three-dimensional planar structures based on the so-called “woodpile” lattice. We demonstrate guiding of a speed-of-light accelerating mode by a defect in the photonic crystal lattice and discuss the properties of this mode. We also discuss particle beam dynamics in the structure, presenting a novel method for focusing the beam. In addition we describe some potential coupling methods for the structure.
The Most Probable Cause for the High Gamma-Ray Polarization in GRB 021206

The exciting detection of a very high degree of linear polarization, , in the prompt g-ray P p 80% 20% emission of the recent gamma-ray burst GRB 021206 provides strong evidence that synchrotron emission is the dominant radiation mechanism. Besides this immediate implication, there were also claims that this implies a magnetic field that is ordered on large scales within the ejecta and must therefore be produced at the source, which in turn was used as an argument in favor of magnetic fields playing an active role in the production of GRB jets. However, an alternative explanation was also suggested: a very narrow jet, of opening angle , where is the v ∼ 1/ gg 100 j Lorentz factor during the GRB, viewed slightly outside its edge, at . This explanation also works v ! v v 1/g j obs j with a magnetic field that is generated in the internal shocks and does not originate at the source. We calculate the expected degree of polarization for these two scenarios and find that it is significantly easier to produce with an ordered field. More specifically, we obtain for an ordered transverse magnetic P 50% P ∼ 43%–61% field, , whereas a shock-produced field that is random but fully within the plane of the shock, , can produce B B ord ⊥ up to for a single pulse in the GRB light curve, but the integrated emission over many pulses (as P 38%–54% measured in GRB 021206) is expected to be a factor of ∼2 lower. A magnetic field normal to the shock front, , can produce for the emission integrated over many pulses. However, polarization measurements BP ∼ 35%–62% k from GRB afterglows suggest a more isotropic configuration for the shock-produced field that should reduce P by a factor of ∼2–3. Therefore, an ordered magnetic field, , that originates at the source can produce the observed Bord polarization most naturally, while is less likely, and is the least likely of the above. BB k
Replacing the nucleobases in DNA with designer molecules.

DNA is not only a carrier of genetic information, but it is also a versatile supramolecular scaffold, arranging smaller organic structures into predesigned geometries. Herein are discussed molecular strategies in which the natural DNA bases on the sugar−phosphate backbone are replaced by other molecules. Some of the base replacements under study include fluorophores, ligands for metals, helix stabilizers, and DNA base shape mimics.
Synthesis, reactivity, x-ray structure and thermal study of the mixed-metal oxide hydrate [Mn(H2O)2V2O6]

Abstract The mixed-metal oxide hydrate Mn(H2O)2V2O6 (1) has been prepared by the reaction of potassium vanadate with manganese chloride tetrahydrate in aqueous reaction medium at 70–72 °C. The orange-red crystals of (1) have been characterized by FT-IR, Raman, and UV-VIS spectroscopy, thermogravimetric analysis, magnetic susceptibility measurement, and complete single crystal x-ray structure analysis. The structure of (1) consists of the stacks of zigzag chains of corner sharing VO4 tetrahedra cross-linked by MnO4(H2O)2 octahedral units generating a complex Mn/O/V/O network. The structure exhibits cavities and tunnels delimited by four and six polyhedra. Thermal treatment of (1) under nitrogen atmosphere results into the removal coordinated water. The dehydrated samples of (1) exhibits reversible water absorption. Observed room temperature magnetic moment (5.87 BM) of (1) is consistent with the presence of high-spin Mn(II) centers. Crystal data for (1): Orthorhombic space group Pnrna (No. 62), a = 5.6085(6), b = 10.917(16), c = 12.042(2) A, V = 737.3(2) A3, Z = 4. The reactions of (1) with some simple ligands is described.