cssi/SciSciGPT-SciSciNet huggingface dataset:
Controlling the regiochemistry of nucleophilic attack on unsymmetrical allyl complexes

Abstract The NO and CO ligands in a [CpMo(NO)(CO)(η 3 -allyl)] + complex exert differential electronic effects on the allyl moiety and control the regiochemistry of nucleophilic attack. These directing influences are sufficiently strong that they overcome the normal directing influences of substituents of the allyl moiety. An essential task, therefore, is arranging for the appropriate terminus of the allyl to have the relationship to the nitrosyl group that will result in attack at the desired location. Replacement of a single CO ligand in a neutral monosubstituted allyl complex of CpMo(CO) 2 with NO + yields a product for which addition occurs at the unsubstituted end of the allyl. Hence, an E -olefin with no newly created chiral centers is formed upon nucleophilic attack. A new synthetic strategy has been developed which allows us to build a chiral center in the alylic position of a terminal olefin. Sequential addition of two nucleophiles to a CpMo(NO)(CO)(allyl) + cation creates these chiral centers, which were not accessible by addition of NO + to the dicarbonyl. Addition of nucleophiles to homochiral (Neomenthylcyclopentadienyl)Mo(NO)(CO)(phenylallyl) + complexes yields chiral olefins in high enantiomeric purity. The cationic phenylallyl complexes prepared by different routes were identified by single crystal X-ray diffraction determinations. endo-cis-syn -[CpMo(NO)(CO)(η 3 -CH(Ph)CHCH 2 )]BF 4 crystallizes in the monoclinic space group P 2 1 / n with a 8.226(2), b 12.273(2), c 16.051(2) A, β 100.02(2)°, V 1595.7(9) A 3 , Z = 4. exo -cis-syn-[CpMo(NO)(CO)(η 3 -CH(Ph)CHCH 2 )]BF 4 crystallizes in the monoclinic space group P 2 1 / c with a 10.706(3), b 14.700(4), c 10.491(3) A, β 96.48(2)°, V 1640.5 A 3 , Z = 4.
A Real-Time Automated Point-Process Method for the Detection and Correction of Erroneous and Ectopic Heartbeats

The presence of recurring arrhythmic events (also known as cardiac dysrhythmia or irregular heartbeats), as well as erroneous beat detection due to low signal quality, significantly affects estimation of both time and frequency domain indices of heart rate variability (HRV). A reliable, real-time classification and correction of ECG-derived heartbeats is a necessary prerequisite for an accurate online monitoring of HRV and cardiovascular control. We have developed a novel point-process-based method for real-time R-R interval error detection and correction. Given an R-wave event, we assume that the length of the next R-R interval follows a physiologically motivated, time-varying inverse Gaussian probability distribution. We then devise an instantaneous automated detection and correction procedure for erroneous and arrhythmic beats by using the information on the probability of occurrence of the observed beat provided by the model. We test our algorithm over two datasets from the PhysioNet archive. The Fantasia normal rhythm database is artificially corrupted with known erroneous beats to test both the detection procedure and correction procedure. The benchmark MIT-BIH Arrhythmia database is further considered to test the detection procedure of real arrhythmic events and compare it with results from previously published algorithms. Our automated algorithm represents an improvement over previous procedures, with best specificity for the detection of correct beats, as well as highest sensitivity to missed and extra beats, artificially misplaced beats, and for real arrhythmic events. A near-optimal heartbeat classification and correction, together with the ability to adapt to time-varying changes of heartbeat dynamics in an online fashion, may provide a solid base for building a more reliable real-time HRV monitoring device.
2-Heterocyclic indole-3-sulfones as inhibitors of HIV-1 reverse transcriptase

Abstract A variety of 2-heterocycle substituted 3-phenysulfonyl-5-chloroindoles were investigated as replacements for the 2-carboxamide functionality of the potent HIV-1 reverse transcriptase inhibitor L-737, 126. The 2-carboxamide series of compounds typified by L-737,126 have poor solubility. Replacement of the carboxamide moiety with a variety of heterocycles results in a series of potent enzyme inhibitors with equivalent ex vivo antiviral activity and improved physicochemical properties.
Renormalization of QED Near Decoupling Temperature

We study the effective parameters of QED near decoupling temperatures and show that the QED perturbative series is convergent, at temperatures below the decoupling temperature. The renormalization constant of QED acquires different values if a system cools down from a hotter system to the electron mass temperature or heats up from a cooler system to the same temperature. At , the first order contribution to the electron self-mass, is 0.0076 for a heating system and 0.0115 for a cooling system and the difference between two values is equal to 1/3 of the low temperature value and 1/2 of the high temperature value around . This difference is a measure of hot fermion background at high temperatures. With the increase in release of more fermions at hotter temperatures, the fermion background contribution dominates and weak interactions have to be incorporated to understand the background effects.
Genetic Rescue of Glycosylation-deficient Fgf23 in the Galnt3 Knockout Mouse

Fibroblast growth factor 23 (FGF23) is a hormone that inhibits renal phosphate reabsorption and 1,25-dihydroxyvitamin D biosynthesis. The FGF23 subtilisin-like proprotein convertase recognition sequence (176RHTR179↓) is protected by O-glycosylation through ppGalNAc-T3 (GALNT3) activity. Thus, inactivating GALNT3 mutations render FGF23 susceptible to proteolysis, thereby reducing circulating intact hormone levels and leading to hyperphosphatemic familial tumoral calcinosis. To further delineate the role of glycosylation in the Fgf23 function, we generated an inducible FGF23 transgenic mouse expressing human mutant FGF23 (R176Q and R179Q) found in patients with autosomal dominant hypophosphatemic rickets (ADHR) and bred this animal to Galnt3 knockout mice, a model of familial tumoral calcinosis. Due to the low intact Fgf23 level, Galnt3 knockout mice with wild-type Fgf23 alleles were hyperphosphatemic. In contrast, carriers of the mutant FGF23 transgene, regardless of Galnt3 mutation status, had significantly higher serum intact FGF23, resulting in severe hypophosphatemia. Importantly, serum phosphorus and FGF23 were comparable between transgenic mice with or without normal Galnt3 alleles. To determine whether the presence of the ADHR mutation could improve biochemical and skeletal abnormalities in Galnt3-null mice, these mice were also mated to Fgf23 knock-in mice, carrying heterozygous or homozygous R176Q ADHR Fgf23 mutations. The knock-in mice with functional Galnt3 had normal Fgf23 but were slightly hypophosphatemic. The stabilized Fgf23 ADHR allele reversed the Galnt3-null phenotype and normalized total Fgf23, serum phosphorus, and bone Fgf23 mRNA. However, the skeletal phenotype was unaffected. In summary, these data demonstrate that O-glycosylation by ppGaINAc-T3 is only necessary for proper secretion of intact Fgf23 and, once secreted, does not affect Fgf23 function. Furthermore, the more stable Fgf23 ADHR mutant protein could normalize serum phosphorus in Galnt3 knockout mice.
Weak lensing ellipticities in a strong lensing regime

It is now routine to measure the weak gravitational lensing shear signal from the mean ellipticity of distant galaxies. However, conversion between ellipticity and shear assumes local linearity of the lensing potential (i.e., that the spatial derivatives of the shear are small), and this condition is not satisfied in some of the most interesting regions of the sky. We extend a derivation of lensing equations to include higher order terms, and assess the level of biases introduced by assuming that first-order weak-lensing theory holds in a relatively strong shear regime. We find that even in a worst-case scenario, a fully linear analysis is accurate to within 1% outside ~1.07 times the Einstein radius of a lens, by deriving an analytic function that can be used to estimate the applicability of any first-order analysis. The effect is too small to explain the discrepancy between weak- and strong-lensing estimates of the mass of the Bullet Cluster, and should not impact cluster surveys for the foreseeable future. In fact, it means that arclets can be used to measure shears closer to a cluster core than has been generally appreciated. However, the bias is significant for galaxy group or galaxy-galaxy lensing applications. At the level of accuracy demanded by dedicated future surveys, it also needs to be considered for measurements of the inner slope of cluster mass distributions and the small-scale end of the mass power spectrum.
Synthesis and Phase Stability of Metastable Bixbyite V2O3 Colloidal Nanocrystals

We have recently developed a colloidal route to vanadium sesquioxide (V2O3) nanocrystals with a metastable bixbyite crystal structure. In addition to being one of the first reported observations of the bixbyite phase in V2O3, it is also one of the first successful colloidal syntheses of any of the vanadium oxides. The nanocrystals, measuring 5 to 30 nm in diameter, possess a flower-like morphology which densify into a more spherical shape as the reaction temperature is increased. The bixbyite structure was examined by X-ray diffraction and an aminolysis reaction pathway was determined by Fourier transform infrared spectroscopy. A direct band gap of 1.29 eV was calculated from optical data. Under ambient conditions, the structure was found to expand and become less distorted, as evidenced by XRD. This is thought to be due to the filling of structural oxygen vacancies in the bixbyite lattice. The onset of the irreversible transformation to the thermodynamically stable rhombohedral phase of V2O3 occurred jus...
Electrical Behavior of Long Linac Tanks and a New Tank-Coupling Scheme

The electrical behavior of long linac tanks can be represented by the behavior of a finite chain of coupled harmonic oscillators.1 A theory is given of chains of oscillators of two kinds, which is appropriate for semi-resonant or resonant coupling structures.2 The perturbation theory given previously is extended to predict the effects of errors in the coupling cells and in the main cells.2 Some advantages of ?/2 mode operation of the double chain are discussed. A new accelerating scheme is presented in which the coupling structures are resonant and the tanks are resonantly coupled. The theory, numerical calculations, and measurements on laboratory models3 all indicate that tolerances on power amplifier voltage and phase can be relaxed by as much as a factor of five.
Frequency-Steered Acoustic Arrays: Application to Structural Health Monitoring of Composite Plates

This paper presents the design, characterization, and application of periodic piezoelectric actuator arrays for structural health monitoring. In the proposed array configuration, all elements are activated simultaneously to achieve strong frequency-dependent directional actuation, which allows beam steering through a sweep of the excitation frequency and limited hardware requirements. The array enables in situ monitoring of critical components through strongly focused actuation and directional scanning capabilities. The concept is illustrated for a selected design with quadrilateral topology on an isotropic plate. The application to composite panels is also specifically discussed by illustrating the complexity of the corresponding dispersion properties, which suggest design challenges for mode tuning. A quadrilateral design is tested for excitation of the A 0 mode on a selected lay-up sequence to illustrate the generality of the proposed concept and its applicability to composites.
COMET: A Recipe for Learning and Using Large Ensembles on Massive Data

COMET is a single-pass MapReduce algorithm for learning on large-scale data. It builds multiple random forest ensembles on distributed blocks of data and merges them into a mega-ensemble. This approach is appropriate when learning from massive-scale data that is too large to fit on a single machine. To get the best accuracy, IVoting should be used instead of bagging to generate the training subset for each decision tree in the random forest. Experiments with two large datasets (5GB and 50GB compressed) show that COMET compares favorably (in both accuracy and training time) to learning on a sub sample of data using a serial algorithm. Finally, we propose a new Gaussian approach for lazy ensemble evaluation which dynamically decides how many ensemble members to evaluate per data point, this can reduce evaluation cost by 100X or more.
How Adequate is Digital Rectal Exam for Prostate Cancer Screening at Colonoscopy? Can Adequacy be Improved?

Purpose Screening by digital rectal exam (DRE) has been advocated as a means of detecting early-stage prostate cancer. We sought to determine the adequacy of prostate palpation at DRE at colonoscopy, and to devise a method of improving adequacy when the gland is incompletely felt. Materials and Methods Adequacy of prostate palpation in the left lateral position was prospectively assessed in 200 males 40 years or older undergoing colonoscopy, and correlated with body mass index (BMI) and National Institutes of Health (NIH) weight categories. If the prostate was incompletely felt, the patient was asked to flex his knee(s) up toward his chest, and then the exam was repeated. Results The prostate was incompletely felt on initial DRE in 65 of 200 patients (32.5%). Raising the knee(s) toward the chest permitted complete palpation in 62 of those 65 cases. Incomplete palpation showed a strong correlation with BMI (P < 0.0001) and weight category: 3/36 (8.3%) for patients with normal body weight, 14/89 (15.7%) for overweight, 42/68 (61.8%) for obesity, and 6/7 (85.7%) for extreme obesity (P < 0.0001). There were 13 patients in whom no part of the prostate gland could be felt on the initial DRE, and which also correlated with NIH weight class (P < 0.0001). Conclusions The prostate gland is often incompletely palpated at DRE in the left lateral position at colonoscopy, and shows a strong correlation with obesity. Adequacy can be dramatically improved by having the patient raise his knee(s) up toward his chest, a maneuver that takes just seconds to perform.
In Situ Raman Spectroscopy of COOH-Functionalized SWCNTs Trapped with Optoelectronic Tweezers

Optoelectronic tweezers (OETs) were used to trap and deposit aqueous dispersions of carboxylic-acid-functionalized single-walled carbon nanotube bundles. Dark-field video microscopy was used to visualize the dynamics of the bundles both with and without virtual electrodes, showing rapid accumulation of carbon nanotubes when optical virtual electrodes are actuated. Raman microscopy was used to probe SWCNT materials following deposition onto metallic fiducial markers as well as during trapping. The local carbon nanotube concentration was observed to increase rapidly during trapping by more than an order of magnitude in less than one second due to localized optical dielectrophoresis forces. This combination of enrichment and spectroscopy with a single laser spot suggests a broad range of applications in physical, chemical, and biological sciences.
Strain localization in ductile single crystals

Strain localization in ductile crystals deforming by single slip was analyzed. The plastic flow is modeled as rate-in-sensitive; and localization, viewed as a bifurcation from a homogeneous deformation mode to one which is concentrated in a narrow ''shear band'', is found to be possible only when the plastic hardening modulus for the slip system has fallen to a certain critical value, h/sub cr/, where h/sub cr/ is sensitive to the precise form of the constitutive law governing incremental shear. The general form of this constitutive law is developed. Incorporated within it is the possibility of deviations from the Schmid rule of a critical resolved shear stress. It is shown that h/sub cr/ may in fact be positive when there are deviations from the Schmid rule. It is suggested that micromechanical processes such as ''cross-slip'' in crystals provide specific cases for which stresses other than the Schmid stress may influence plastic response and, further, there is an experimental association of localization with the onset of large amounts of cross-slip. The specific form of h/sub cr/ is given for a constitutive model that corresponds to the non-Schmid effects in cross-slip, and a dislocation model of the process is developed from which anmore » estimate of the magnitude of the parameters involved is made. The work supports the notion that localization can occur with positive strainhardening, h/sub cr/ greater than 0, and the often-invoked notions of the attainment of an ideally plastic or strain softening state for localization may be unnecessary. 6 figures.« less
Corporate risk management: evidence from product liability

In this paper we examine the factors that determine how firms manage large, firm-specific risks, in this case, product liability. The risk of being sued for defective products or damage from defective products poses a small probability of a great loss to the firm. Product liability exposure arises from the firm's choice of products and markets; choices that are fundamental to the firm's business strategy and that are costly to alter. Firms are unlikely to be naturally hedged by cash flows with respect to product liability risk. Cash flows will likely be negatively correlated with product liability claims since product liability claims reduce product demand and increase costs through legal expenses and claims payments.
Surface acoustic wave gas sensor based on film conductivity changes

Abstract The first surface acoustic wave (SAW) sensor that functions via changes in conductivity of a thin surface film is reported. A lead phthalocyanine (PbPc) thin film is deposited on the acoustic propagation path of a LiNbO 3 SAW delay line, which serves as the feedback element of an oscillator circuit. Reaction with strongly oxidizing gases, in particular NO 2 , increases the conductivity of the PbPc film. Acousto-electric coupling of the traveling electric potential wave associated with the SAW to charge carriers in the PbPc film slows the acoustic wave velocity, altering the oscillation frequency of the circuit. This sensor is about 1000 times more sensitive, in terms of the number of NO 2 molecules that can be detected (10 16 molecules/cm 3 of PbPc film), than an identical SAW sensor functioning via mass loading would be. Sensitivity to a few ppm of NO 2 in N 2 has been demonstrated.
The impact of local governance institutions on foreign market listings: The case of Chinese firms

Abstract This paper exploits the substantial variation in market institutions across provinces in China to examine the impact of institutional quality on foreign listing. Firms that are listed on the U.S. and U.K. exchanges are more likely to come from better regulated provinces and tend to be at the top of a corporate pyramid. However, though the impact on firm performance of market institutions and pyramidal affiliations persists briefly post-listing with firms recording lower EPS and higher raw returns in the first year, it does not help predict whether firms remain listed abroad in 2012. Thus, we conclude that headquarters' market institutions shape a firm through time of listing and have diminished influence over time.
Some Economic Effects of Unilateral and Multilateral Reductions in Military Expenditures in the Major Industrialized and Developing Countries

We use the Michigan Model of World Trade and Production to assess the sectoral effects on the U.S. economy of: (1) a 25% unilateral reduction of military expenditures in the United States and (2) a 25% multilateral reduction of military expenditures in all of the major Western industrialized and developing countries included in the Michigan Model. Our principal findings suggest that the overall effects are not substantial. Although the sectoral results differ significantly depending on the alternative assumptions concerning compensating macroeconomic policies, less than 1.0% of the workforce might experience dislocation in all cases. The results of the multilateral reduction are qualitatively similar to those of a unilateral reduction.
Lead‐Acid Batteries: Use of Carbon Fiber‐Lead Wire Grids at the Positive Electrode

Conducting carbon fibers were introduced into the positive grid of the lead‐acid battery in a structure which resembled a grid of pipecleaners. The carbon fibers are compatible with the environment of the positive electrode of the cell. In conjunction with Pb‐Ca‐Sn alloy wires or pure lead wires, the fibers prolong the cycle life of the battery, increase the high discharge rate capability, and can decrease the weight of the battery. Scanning electron microscopy showed the function of the carbon fibers to be an extension of the lead wire grid, thereby participating in the solution‐precipitation mechanism of the electrode reaction. For comparison, a grid with glass fibers was also studied.
Response of gravity level fluctuations on the Gravity Probe-B spacecraft propellant system

Time-dependent computations have been performed to investigate the dynamical behaviors of fluid under a microgravity environment. A computer algorithm is introduced which can be used to simulate the fluid behavior in that environment, in particular the excitation of sloshing waves due to different gravity environments and rotation speeds. A suggestion on the proper handling and managing of cryogenic fluid propellant to be used in the Gravity Probe-B spacecraft propulsion is made.
The Attractiveness of Enriched and Impoverished Options: Culture, Self-Construal, and Regulatory Focus

The authors propose that there is a systematic impact of a person's activated self-construal (interdependent vs. independent) on the evaluation of enriched and impoverished options. This hypothesis is tested using a cross-country comparison of participants from China and the United States (Study 1) and by priming self-construal (Study 2) and regulatory focus (Study 3). Results show that people with an independent self-construal and a promotion focus perceive enriched options as more attractive than impoverished options. Conversely, people with an interdependent self-construal and a prevention focus perceive enriched options as less attractive than impoverished options. Mediation analyses show that the effect of cultural orientation operates through self-construal. In turn, self-construal operates through activated regulatory focus. Analysis of cognitive responses shows that the effect of regulatory focus is mediated by positive/negative thoughts about option attributes.
Consumption Time in Household Production: Implications for the Goods-Time Elasticity of Substitution

Abstract Under some reasonable assumptions, we show analytically that the goods-time elasticity of substitution will be greater if consumption time is not included as an input. An empirical example with food production is consistent with this result.
Synthesis of isochromene-type scaffolds via single-flask Diels-Alder-[4 + 2]-annulation sequence of a silyl-substituted diene with menadione.

A sequential Diels–Alder reaction/silicon-directed [4 + 2]-annulation was developed to assemble hydroisochromene-type ring systems from menadione 2. In the first step, a Diels–Alder of the 1-silyl-substituted butadiene 1 with 2 furnished an intermediate cyclic allylsilane. Subsequently, TMSOTf promoted a [4 + 2]-annulation through trapping of an oxonium, generated by condensation between an aldehyde and the TBS protected alcohol resulted in the formation of a cis-fused hydroisochromene 13.
Patient Survival After Renal Transplantation: I. The Impact of Dialysis Pre-Transplant

Patient survival after renal transplantation: I. The impact of dialysis pre-transplant. Patients on dialysis and recipients of renal transplants have higher mortality than individuals without kidney disease. In this study we evaluated the possible impact of dialysis therapy before transplantation on patient survival after the transplant. This analysis includes all of the patients who received a cadaveric renal transplant at The Ohio State University from 1984 to 1991 and who remained alive with functioning grafts for at least six months after the transplant ( N = 523). After a follow-up of 84 ± 14 months, 28% of the patients died and 23% lost their grafts. By multivariate analysis, reduced patient survival (censored at the time of graft loss) correlated with these pre-transplant variables: Older age ( P P = 0.0002), smoking ( P = 0.009), and the length of time on dialysis ( P = 0.0002). Thus, 7% of patients who were never dialyzed, 23% of those dialyzed for less than three years, and 44% of patients dialyzed for ≥ three years died post-transplant. By Cox regression, patient survival months correlated with time on dialysis pre-transplant ( P = 0.0003). The type of dialysis (CAPD vs. hemodialysis) did not correlate with patient survival. Graft survival, censored for patient death, did not correlate with any of these pre-transplant variables. The relationship between time on dialysis and patient mortality is due to at least two factors: ( 1 ) transplant recipients who had dialysis for ≥ 3 years had higher mortality due to infections (22%) than those who had dialysis for P = 0.01 by X 2 ); and ( 2 ) increasing time on dialysis increases the prevalence of both left ventricular hypertrophy ( P = 0.008) and cardiomegaly ( P = 0.004), and these relationships are statistically independent of other factors that also correlate with the prevalence of cardiovascular disease. In conclusion, increased time on dialysis prior to renal transplantation is associated with decreased survival of transplant recipients.
Current Fluctuations for Independent Random Walks in Multiple Dimensions

Consider a system of particles evolving as independent and identically distributed (i.i.d.) random walks. Initial fluctuations in the particle density get translated over time with velocity \(\vec{v}\), the common mean velocity of the random walks. Consider a box centered around an observer who starts at the origin and moves with constant velocity \(\vec{v}\). To observe interesting fluctuations beyond the translation of initial density fluctuations, we measure the net flux of particles over time into this moving box. We call this the “box-current” process.
Corrugated multi-supersheets

We explore the multi-superthreads and supersheets solutions of six-dimensional $ \mathcal{N} $ =1 supergravity coupled to a tensor multiplet. The solutions carry D1-D5-P charges, but no Kaluza-Klein monopole. We lay down the formalism to construct multiple super-sheets with arbitrary and independent profiles. The solution is by construction free of Dirac strings in contrast to the five-dimensional construction where one has to separately solve integrability conditions. We explore this formalism to construct supersheets that fluctuate in both directions allowing a more general choice of profiles. These new solutions are genuinely six-dimensional, singular, fluctuating BPS solutions and by analyzing them we expect to learn more about the conjectured superstrata. We also derive the conditions under which different supersheets can touch, or even intersect through each other.
Models of space-averaged energetics of plates

The analysis of high frequency vibrations in plates is of particular interest in the study of structure borne noise in aircrafts. The current methods of analysis are either too expensive (finite element method) or may have a confidence band wider than desirable (Statistical Energy Analysis). An alternative technique to model the space and time averaged response of structural acoustics problems with enough detail to include all significant mechanisms of energy generation, transmission, and absorption is highly desirable. The focus of this paper is the development of a set of equations which govern the space and time averaged energy density in plates. To solve this equation, a new type of boundary value problem must be treated in terms of energy density variables using energy and intensity boundary conditions. A computer simulation verification study of the energy governing equation is performed. A finite element formulation of the new equations is also implemented and several test cases are analyzed and compared to analytical solutions.
On Independence For Non-Additive Measures, With a Fubini Theorem

Recent models of decision making represent agents' beliefs by non-additive set-functions. An important technical question which arises in applications to diverse areas of economics is how to define independence of such set-functions. After arguing that the straightforward generalization of independence does not in general yield a unique product, in this work I show that, while Fubini's theorem is in general false if additivity is not granted, it is true when a certain type of function is being integrated. For these functions the iterated integrals coincide with the integral with respect to products which satisfy a certain property, strictly stronger than independence. I show that most of the assumptions made in these results are very close to being necessary. In general the mentioned property is still not strong enough to uniquely define a product. On the other hand I discuss some proposals which have been made in the literature, and I show that unicity can however be obtained when the product is assumed to be a belief function. Moreover I show that the unique product thus obtained has an intuitive justification when the marginals are distributions induced by random correspondences. Finally I use the results in the paper to discuss the question of randomization in decision models with non-additive beliefs.
The Discovery of a Novel Route to Highly Substituted α-Tropolones Enables Expedient Entry to the Core of the Gukulenins

A simple and general method for the synthesis of highly substituted α-tropolone ethers that allows rapid access to the bis(tropolone) core of the antiproliferative metabolites (−)-gukulenins A and F (3, 4) is described. The reaction proceeds by thermolytic opening of gem-dibromobicyclo[4.1.0]heptane intermediates, which are readily accessed from simple starting materials. Mechanistic studies suggest the reaction proceeds via an autocatalytic process mediated by methyl hypobromite. This synthetic sequence allows access to a broad array of highly substituted α-tropolones.
An efficient synthesis of (Z)-γ-fluoroallylphosphonates using a base-promoted deconjugation of (E)-γ-fluorovinylphosphonates, and its utility as fluoroolefin-containing building block

Abstract A three-step synthesis of γ-fluoroallylphosphonates starting with α,β-unsaturated aldehydes is described. Treatment with diethyl phosphite in the presence of KF gives α-hydroxyallyl phosphonate in excellent yield; DAST deoxofluorination produces the corresponding γ-fluorovinylphosphonate through a S N 2′ mechanism, and finally, a base-promoted double bond migration leads to the desired γ-fluoroallylphosphonate. γ-Fluoroallylphosphonate is a useful building block in the synthesis of fluoroolefins. An exploratory study yielded excellent yields of ( Z )-diethyl 1-benzyl-3-fluoro-2-butenylphosphonate and ( Z )-diethyl 1,3-difluoro-2-hexenylphosphonate. Treatment of ( E )-diethyl 3-fluoro-2-hexenylphosphonate with LiN(TMS) 2 and benzaldehyde in THF led to the preferential formation of syn -( Z )-diethyl 3-fluoro-1-(hydroxybenzyl)-2-butenylphosphonate.
Kaon physics at BNL

The rare kaon decay program at BNL is summarized. A brief review of recent results is provided along with a discussion of prospects for the future of this program. The primary focus is the two golden modes: K{sup +} {yields} {pi}{sup +} {nu}{bar {nu}} and K{sub L}{sup o} {yields} {pi}{sup o} {nu}{bar {nu}}. The first step in an ambitious program to precisely measure both branching ratios has been successfully completed with the observation of two K{sup +} {yields} {pi}{sup +} {nu}{bar {nu}} events by E787. The E949 experiment is poised to reach an order of magnitude further in sensitivity and to observe {approx}10 Standard Model events.
Heavy ion collisions with transverse dynamics from evolving AdS geometries

Currently there exists no known way to construct the Stress-Energy Tensor (Tμν) of the produced medium in heavy ion collisions at strong coupling from purely theoretical grounds. In this paper, some steps are taken in that direction. In particular, the evolution of Tμν at strong coupling and at high energies is being studied for early proper times (τ). This is achieved in the context of the AdS/CFT duality by constructing the evolution of the dual geometry in an AdS5 background. Improving the earlier works in the literature, the two incident nuclei have an impact parameter b and a non-trivial transverse profile. The nuclear matter is modeled by two shock waves corresponding to a non-zero five dimensional bulk Stress-Energy Tensor JMN. An analytic formula for Tμν at small τ is derived and is used in order to calculate the momentum anisotropy and spatial eccentricity of the medium produced in the collision as a function of the ratio \( \frac{\tau }{b} \). The result for eccentricity at intermediate \( \frac{\tau }{b} \) agrees qualitatively with the results obtained in the context of perturbation theory and by using hydrodynamic simulations. Finally, the problem of the negative energy density and its natural connection to the eikonal approximation is discussed.
Simple Markov-chain algorithms for generating bipartite graphs and tournaments

We consider two problems: randomly generating labeled bipartite graphs with a given degree sequence and randomly generating labeled tournaments with a given score sequence. We analyze simple Markov chains for both problems. For the first problem, we cannot prove that our chain is rapidly mixing in general, but in the near-regular case, i.e., when all the degrees are almost equal, we give a proof of rapid mixing. Our methods also apply to the corresponding problem for general (nonbipartite) regular graphs, which was studied earlier by several researchers. One significant difference in our approach is that our chain has one state for every graph (or bipartite graph) with the given degree sequence; in particular, there are no auxiliary states as in the chain used by Jerrum and Sinclair. For the problem of generating tournaments, we are able to prove that our Markov chain on tournaments is rapidly mixing, if the score sequence is near-regular. The proof techniques we use for the two problems are similar. ©1999 John Wiley & Sons, Inc. Random Struct. Alg., 14: 293–308, 1999
A comparison of domain decomposition techniques for elliptic partial differential equations and their parallel implementation

Several preconditioned conjugate gradient (PCG)-based domain decomposition techniques for self-adjoint elliptic partial differential equations in two dimensions are compared against each other and against conventional PCG iterative techniques in serial and parallel contexts. We consider preconditioners that make use of fast Poisson solvers on the subdomain interiors. Several preconditioners for the interfacial equations are tested on a set of model problems involving two or four subdomains, which are prototypes of the stripwise and boxwise decompositions of a two-dimensional region. Selected methods have been implemented on the Intel Hypercube by assigning one processor to each subdomain, making use of up to 64 processors. The choice of a “best” method for a given problem depends in general upon: (a) the domain geometry, (b) the variability of the operator, and (c) machine characteristics such as the number of processors available and their interconnection scheme, the memory available per processor, and c...
Teichmüller theory of the punctured solenoid

The punctured solenoid $${\mathcal H}$$ plays the role of an initial object for the category of punctured surfaces with morphisms given by finite covers branched only over the punctures. The (decorated) Teichmuller space of $${\mathcal H}$$ is introduced, studied, and found to be parametrized by certain coordinates on a fixed triangulation of $${\mathcal H}$$ . Furthermore, a point in the decorated Teichmuller space induces a polygonal decomposition of $${\mathcal H}$$ itself giving a combinatorial description of the decorated Teichmuller space. This is used to obtain a non-trivial set of generators of the modular group of $${\mathcal H}$$ , and each word in these generators admits a normal form. There is furthermore a non-degenerate modular group invariant two form on the Teichmuller space of $${\mathcal H}$$ . All of this structure is in perfect analogy with that of the decorated Teichmuller space of a punctured surface of finite type.
Carbon Deficiency in Externally Polluted White Dwarfs: Evidence for Accretion of Asteroids

Existing determinations show that n(C)/n(Fe) is more than a factor of 10 below solar in the atmospheres of three white dwarfs that appear to be externally polluted. These results are not easily explained if the stars have accreted interstellar matter, and we reinterpret these measurements as evidence that these stars have accreted asteroids with a chondritic composition.
Thermodynamic−Kinetic Correlations in Supercooled Liquids: A Critical Survey of Experimental Data and Predictions of the Random First-Order Transition Theory of Glasses

Thermodynamics and kinetics are thought to be linked in glass transitions. The quantitative predictions of α-relaxation activation barriers provided by the theory of glasses based on random first-order transitions are compared with the experimental results for 44 substances. The agreement found between the predicted activation energies near Tg and experiment is excellent. These predictions depend on the configurational heat capacity change on vitrification and the entropy of melting the crystal which are experimental inputs.
The Mitochondrial Genome of Phoronis architecta—Comparisons Demonstrate that Phoronids Are Lophotrochozoan Protostomes

The proper reconstruction of the relationships among the animal phyla is central to interpreting patterns of animal evolution from the genomic level to the morphological level. This is true not only of the more speciose phyla, but also of smaller groups. We report here the nearly complete DNA sequence of the mitochondrial genome of the phoronid Phoronis architecta, which has a gene arrangement remarkably similar to that of a protostome animal, the chiton Katharina tunicata. Evolutionary analysis of both gene arrangements and inferred amino acid sequences of these taxa, along with those of three brachiopods and other diverse animals, strongly supports the hypothesis that lophophorates are part of the large group that includes mollusks and annelids, i.e., the Lophotrochozoa, and solidly refutes the alternative of their being deuterostomes.
Diagnosis of cruciate ligament injury using single contrast arthrography

To evaluate the accuracy of arthrography for assessing the status of the anterior cruciate ligament (ACL), 212 arthrograms from 212 knees in 205 consecutive patients undergoing single contrast arthrography and subsequent arthroscopy or arthrotomy were reviewed. Criteria for evaluation of the ACL included the clarity of its radiographic appearance as well as the anterior laxity of the knee as seen on manual stress views. Of the 111 knees having intact ACLs at surgery, 98 (88%) were evaluated correctly by arthrography. Of the 101 knees having a damaged ACL, 85 were read as torn or attenuated on the arthrogram. When the torn and attenuated ligaments were considered separately, accuracy was decreased. Of the 87 ligaments actually torn, 68 (78%) were read as torn and 9 (10%) as attenuated. Of the 14 actually attenuated, 5 (36%) were read as attenuated and 3 (21%) as torn. Of 114 arthrograms read as intact, 98 (86%) were correct. Of 77 arthrograms read as torn, 68 (88%), were correct. Of 21 arthrograms read as attenuated, 5 (24%) were correct. Of 114 torn medial menisci, 112 (98%) were correctly diagnosed, as were 38 (69%) of 55 torn lateral menisci. Sixteen of the 17 missed lateral meniscus tears were in knees with torn medial menisci. Single contrast arthrography is, therefore, highly accurate in distinguishing intact from damaged ACLs. The distinction between torn and attenuated ligaments, however, is not valuable.
Speak software and carry a strip chip

A short description of TI's innovative Strip Chip Architectural Topology is given. The key features of the TMS7000 8-bit Microlanguage Processor are listed, and each of the current family members is discussed briefly. The architecture of the 7000 family is reviewed with emphasis placed on those aspects which enhance its programming power. Addressing modes and other software highlights are discussed in some detail, followed by an overview of microprogramming.
On the Excess Dispersion in the Polarization Position Angle of Pulsar Radio Emission

The polarization position angles (P.A.'s) of pulsar radio emission occupy a distribution that can be much wider than what is expected from the average linear polarization and the off-pulse instrumental noise. Contrary to our limited understanding of the emission mechanism, the excess dispersion in P.A. implies that pulsar P.A.'s vary in a random fashion. An eigenvalue analysis of the measured Stokes parameters is developed to determine the origin of the excess P.A. dispersion. The analysis is applied to sensitive, well-calibrated polarization observations of PSR B1929+10 and PSR B2020+28. The analysis clarifies the origin of polarization fluctuations in the emission and reveals that the excess P.A. dispersion is caused by the isotropic inflation of the data-point cluster formed from the measured Stokes parameters. The inflation of the cluster is not consistent with random fluctuations in P.A., as might be expected from random changes in the orientation of the magnetic field lines in the emission region or from stochastic Faraday rotation in either the pulsar magnetosphere or the interstellar medium. The inflation of the cluster, and thus the excess P.A. dispersion, is attributed to randomly polarized radiation in the received pulsar signal. The analysis also indicates that orthogonal polarization modes (OPMs) occur where the radio emission is heavily modulated. In fact, OPMs may occur only where the modulation index exceeds some critical value, βc 0.3.
Database Integrity Monitoring for Synthetic Vision Systems Using Machine Vision and SHADE

In an effort to increase situational awareness, the aviation industry is investigating technologies that allow pilots to visualize what is outside of the aircraft during periods of low-visibility. One of these technologies, referred to as Synthetic Vision Systems (SVS), provides the pilot with real-time computer-generated images of obstacles, terrain features, runways, and other aircraft regardless of weather conditions. To help ensure the integrity of such systems, methods of verifying the accuracy of synthetically-derived display elements using onboard remote sensing technologies are under investigation. One such method is based on a shadow detection and extraction (SHADE) algorithm that transforms computer-generated digital elevation data into a reference domain that enables direct comparison with radar measurements. This paper describes machine vision techniques for making this comparison and discusses preliminary results from application to actual flight data.
The robustness of Okun's law: Evidence from OECD countries

This paper evaluates the robustness of the Okun relationship based on postwar data for 16 OECD countries. While Okun's law is statistically valid for most countries, the quantitative as opposed to qualitative estimates are far from uniform. Estimates are also sensitive to the choice of models, including the first-difference and the “gap” specifications, the relevant data for the latter are constructed alternatively from the HP filter, the Beveridge-Nelson decomposition procedure, and the Kalman filter based on the NAIRU framework. There is mixed evidence of asymmetric behavior, but strong evidence of structural breaks occurring around the 1970s, after which time most countries began to experience a smaller output loss associated with higher unemployment.
Toric Modular Forms And Nonvanishing Of L-Functions

In a previous paper [1], we defined the space of toric forms T (l), and showed that it is a finitely generated subring of the holomorphic modular forms of integral weight on the congruence group Γ1(l). In this article we prove the following theorem: modulo Eisenstein series, the weight two toric forms coincide exactly with the vector space generated by all cusp eigenforms f such that L(f, 1) 6= 0. The proof uses work of Merel, and involves an explicit computation of the intersection pairing on Manin symbols.
MASSCLEANcolors—Mass-dependent Integrated Colors for Stellar Clusters Derived from 30 Million Monte Carlo Simulations

We present Monte Carlo models of open stellar clusters with the purpose of mapping out the behavior of integrated colors with mass and age. Our cluster simulation package allows for stochastic variations in the stellar mass function to evaluate variations in integrated cluster properties. We find that UBVK colors from our simulations are consistent with simple stellar population (SSP) models, provided the cluster mass is large, M cluster ≥ 106 M ☉. Below this mass, our simulations show two significant effects. First, the mean value of the distribution of integrated colors moves away from the SSP predictions and is less red, in the first 107 to 108 years in UBV colors, and for all ages in (V – K). Second, the 1σ dispersion of observed colors increases significantly with lower cluster mass. We attribute the former to the reduced number of red luminous stars in most of the lower mass clusters and the latter to the increased stochastic effect of a few of these stars on lower mass clusters. This latter point was always assumed to occur, but we now provide the first public code able to quantify this effect. We are completing a more extensive database of magnitudes and colors as a function of stellar cluster age and mass that will allow the determination of the correlation coefficients among different bands, and improve estimates of cluster age and mass from integrated photometry.
Hydrogen encapsulation in a silicon clathrate type I structure : Na5.5(H2)2.15Si46: Synthesis and characterization

A hydrogen-encapsulated inorganic clathrate, which is stable at ambient temperature and pressure, has been prepared in high yield. Na5.5(H2)2.15Si46 is a sodium-deficient, hydrogen-encapsulated, type I silicon clathrate. It was prepared by the reaction between NaSi and NH4Br under dynamic vacuum at 300 °C. The Rietveld refinement of the powder X-ray diffraction data is consistent with the clathrate type I structure. The type I clathrate structure has two types of cages where the guest species, in this case Na and H2, can reside: a large cage composed of 24 Si, in which the guest resides in the 6d crystallographic position, and a smaller one composed of 20 Si, in which the guest occupies the 2a position. Solid-state 23Na, 1H, and 29Si MAS NMR confirmed the presence of both sodium and hydrogen in the clathrate cages. 23Na NMR shows that sodium completely fills the small cage and is deficient in the larger cage. The 1H NMR spectrum shows a pattern consistent with mobile hydrogen in the large cage. 29Si NMR ...
Ternary nitrides: a rapidly growing class of new materials

Abstract Recent advances have been made in search on the synthesis and structure of ternary nitrides. The majority of these phases contain discrete nitridometallate anions and are usually electrical insulators. The remainder, with extended structures, may have useful electronic or physical properties.