cssi/SciSciGPT-SciSciNet huggingface dataset:
DUST EMISSION FROM THE PERSEUS MOLECULAR CLOUD

Using far-infrared emission maps taken by IRAS and Spitzer and a near-infrared extinction map derived from 2MASS data, we have made dust temperature and column density maps of the Perseus molecular cloud. We show that the emission from transiently heated very small grains (VSGs) and the big grain dust emissivity vary as a function of extinction and dust temperature, with higher dust emissivities for colder grains. This variable emissivity cannot be explained by temperature gradients along the line of sight or by noise in the emission maps, but it is consistent with grain growth in the higher density and lower temperature regions. By accounting for the variations in the dust emissivity and VSG emission, we are able to map the temperature and column density of a nearby molecular cloud with better accuracy than has previously been possible.
The solar system cratering record: Voyager 2 results at Uranus and implications for the origin of impacting objects

Abstract The cratering record at Uranus shows two different crater populations of different ages. The old crater population occurs on the heavily cratered surfaces of Oberon, Umbriel, and Miranda, while the younger one is found on Titania, Ariel and the resurfaced areas of Miranda. Since only the young population occurs on Titania, this satellite must have experienced a global resurfacing event which obliterated the older population prior to the impact of objects causing the younger one. The old crater population is characterized by an abundance of large craters and a relative paucity of small ones. The young crater population, however, has an abundance of small craters and a paucity of large ones relative to the old population. Furthermore, the abundance of small craters and the paucity of large craters increases with decreasing density. This change in the size distribution is consistent with a population of impactors that evolved with time by mutual collision, and therefore was probably in planetocentric orbits. In fact, both crater populations may be the result of accretional remnants in planetocentric orbits that evolved with time by mutual collisions. If so, then the higher crater density on Miranda compared to Oberon and Umbriel suggests that both Oberon and Umbriel were also resurfaced early in their histories. A comparison of the Solar System cratering record from Mercury to Uranus (19 AU) shows different crater populations at different locations in the Solar System. Computer simulations using a modified Holsapple-Schmidt crater scaling and short-period comet impact velocities to recover the projectile diameters from the cratering record produce different projectile populations in different parts of the Solar System. Furthermore, adjusting the Jovian crater curve to match that in the inner Solar System requires differences in the impact velocities that are unrealistic for objects in heliocentric orbits. These results suggest that the Solar System cratering record cannot be explained by a single family of objects in heliocentric orbits, e.g., comets. One possible explanation is that the cratering record is the result of different families of objects (possibly accretional remnants) indigenous to that region of the Solar System in which the different crater populations are found. Thus, in the inner Solar System, the impactors responsible for heavy bombardment were in heliocentric orbits with semimajor axes less than 3 AU. In the outer Solar System, they may have been in planetocentric orbits around each of the Jovian planets.
Multigrid acceleration and turbulence models for computations of 3D turbulent jets in crossflow

A multigrid method is presented for the calculation of three-dimensional turbulent jets in crossflow. Turbulence closure is achieved with either the standard k-epsilon model or a Reynolds stress model (RSM). Multigrid acceleration enables convergence rates which are far superior to that for a single grid method to be obtained with both turbulence models. With the k-epsilon model the rate approaches that for laminar flow, but with RSM it is somewhat slower. The increased stiffness of the system of equation in the latter may be responsible. Computed results with both turbulence models are compared to experimental data for a pair of opposed jets in crossflow. Both models yield reasonable agreement for the mean flow velocity, but RSM yields better predictions of the Reynolds stresses.
Ciliary neurotrophic factor and its receptors are differentially expressed in the optic nerve transected adult rat retina.

Ciliary neurotrophic factor (CNTF) has been implicated in the survival and regeneration of adult rat retinal ganglion cells (RGCs). Expression of CNTF and its receptors, ciliary neurotrophic factor receptor alpha (CNTFRalpha) and leukemia inhibitory factor receptor (LIFR) was studied in normal, 6-h, 1-, and 3-day optic nerve transected retinas. Optic nerve transection was performed on the right eye in one group. In the other group, it was performed 5 days after intratectal Fluorogold injection. Retinas were studied using immunohistochemical labeling and Western blot analysis. Astrocytes were labeled with GFAP and Muller cells with glutamine synthetase. CNTF was observed in identifiable astrocytes and Muller cells, and its intensity increased in the experimental retinas. CNTFRalpha was localized on RGCs in experimental retinas. LIFR was localized on RGCs and Muller cells in normal and experimental retinas. CNTF and its receptors are differentially expressed after optic nerve transection and could help delay RGC death in such a stressful environment.
Homogeneous Oxidation of Alkanes by Electrophilic Late Transition Metals

The selective oxidation of alkanes is a topic of considerable interest to both industrial and academic chemists. While the initial discovery occurred more than 25 years ago, new developments in alkane oxidation catalyzed by electrophilic late transition metals have provided important mechanistic insights as well as potentially practical methods for alkane transformations.
The Strategic Context of External Network Ties: Examining the Impact of Director Appointments on Board Involvement in Strategic Decision Making

This study examines how external network ties determine a board's ability to contribute to the strategic decision making process. Although the simple number of director appointments to other boards...
Enthalpies of formation of rare earth orthovanadates, REVO4

Abstract Rare earth orthovanadates, RE VO 4 , having the zircon structure, form a series of materials interesting for magnetic, optical, sensor, and electronic applications. Enthalpies of formation of RE VO 4 compounds ( RE =Sc, Y, Ce–Nd, Sm–Tm, Lu) were determined by oxide melt solution calorimetry in lead borate (2PbO·2B 2 O 3 ) solvent at 1075 K. The enthalpies of formation from oxide components become more negative with increasing RE ionic radius. This trend is similar to that obtained for the rare earth phosphates.
An optimal constrained linear inverse method for magnetic source imaging.

Magnetic source imaging is the reconstruction of the current source distribution inside an inaccessible volume from magnetic field measurements made outside the volume. It is possible in many applications to estimate, from prior physiological and anatomical knowledge, the source positions, amplitudes, and correlations, as well as the noise amplitudes and correlations. The optimal constrained linear inverse method (OCLIM) uses this prior knowledge to obtain a minimum meansquare error estimate of the current distribution. OCLIM can be efficiently computed using the Cholesky decomposition, taking about a second on a workstation-class computer for a problem with 64 sources and 144 detectors. Any source and detector configuration is allowed as long as their positions are fixed a priori. Correlations among source and noise amplitudes are permitted. OCLIM reduces to the optimally weighted pseudoinverse method of Shim and Cho if the source amplitudes are independent and identically distributed and to the minimum-norm leastsquares estimate in the limit of no measurement noise or no prior knowledge of the source amplitudes. In the general case, OCLIM has better mean-square error than either previous method. OCLIM appears well suited to magnetic imaging, since it exploits prior information, provides the minimum reconstruction error, and is inexpensive to compute.
Synthesis of 2-aminopurine nucleosides via regiocontrolled glycosylation

Abstract The stereo- and regiocontrolled synthesis of pyranosyl 2-aminopurine nucleosides is described. Coupling of bissilylated N2-acetyl-2-aminopurine with peracetylated glucopyranosides (SnCl4, (CH2Cl)2-MeCN, reflux) afforded good yields of the corresponding N9-β-2-aminopurine nucleosides. Glycosylation of N2-acetyl-2-amino-6-chloropurine could be made to produce either N9-nucleosides (TMSOTf, (CH2Cl)2, reflux), or N7-nucleosides (SnCl4/MeCN, room temperature) selectively. Application of Knapp's thioglycoside procedure (NIS + TfOH, (CH2Cl)2, room temperature) produced the N9-nucleosides with either base. The 2-amino-6-chloropurine derivatives were converted to their corresponding 2-aminopurine nucleosides by hydrogenolysis (H2, Pd/C). A convenient NOESY protocol for establishing base regiochemistry and anomeric stereochemistry is also presented.
Soft-gluon angular screening in heavy-quark fragmentation

Abstract A method to measure the suppression of soft-gluon radiation by a heavy quark (`dead cone') is discussed. We analyse this QCD phenomenon in the framework of the HERA experiment using Monte Carlo simulations.
Braid group action and quantum affine algebras

We lift the lattice of translations in the extended affine Weyl group to a braid group action on the quantum affine algebra. This action fixes the Heisenberg subalgebra pointwise. Loop-like generators of the algebra are obtained which satisfy the relations of Drinfel'd's new realization. Coproduct formulas are given and a PBW type basis is constructed.
Mechanisms of Platelet Capture Under Very High Shear

As a thrombus grows in a stenosis, the lumen narrows producing very high shear rates as blood velocities increase. Binding platelets are subjected to drag forces exceeding 10,000 pN. These forces could be balanced by 100 simultaneous 100 pN GPIbα-vWF-A1 bonds. The density of GPIbα ligands on platelets is sufficiently high; however, platelet capture under high shear would require the vWF-A1 density on the thrombus surface to be increased to over 416 μm−2. A computational model is used to determine platelet capture as a function of shear rate, surface receptor density, surface contact and kinetic binding rate. vWF-A1 density could be increased by: (i) plasma vWF attaching to the thrombus surface and elongating under shear; (ii) elongated vWF strands creating nets with 3-D pockets; and (iii) vWF releasing from activated platelets. With all three events, A1 densities increase with high shear to provide sufficient multivalency (>850 bonds) for capture even at 500,000 s−1. If the on-rate is greater than 108 M−1 s−1, then a platelet could be captured within 3 μs, the time limit to form bonds before the platelet is swept away. This mechanism of vWF nets can capture circulating platelets at a sufficiently high rate to cause arterial thrombotic occlusion.
The diameter of randomly perturbed digraphs and some applications

The central observation of this paper is that if en random arcs are added to any n-node strongly connected digraph with bounded degree then the resulting graph has diameter O(lnn) with high probability. We apply this to smoothed analysis of algorithms and property testing. Smoothed Analysis: Recognizing strongly connected digraphs is a basic computational task in graph theory. Even for digraphs with bounded degree, it is NL-complete. By XORing an arbitrary bounded degree digraph with a sparse random digraph R ∼ Dn,e/n we obtain a “smoothed” instance. We show that, with high probability, a log-space algorithm will correctly determine if a smoothed instance is strongly connected. We also show that if NL n almost-L then no heuristic can recognize similarly perturbed instances of (s,t)-connectivity. Property Testing: A digraph is called k-linked if, for every choice of 2k distinct vertices s1,…,sk,t1,…,tk, the graph contains k vertex disjoint paths joining sr to tr for r = 1,…,k. Recognizing k-linked digraphs is NP-complete for k ≥ 2. We describe a polynomial time algorithm for bounded degree digraphs, which accepts k-linked graphs with high probability, and rejects all graphs that are at least en arcs away from being k-linked. © 2007 Wiley Periodicals, Inc. Random Struct. Alg., 2007
Factors Related to Declining Luteal Function in Women during the Menopausal Transition

Context: Reproductive hormones are incompletely characterized during the menopause transition (MT). Hypothesis: Increased anovulation and decreased progesterone accompany progress through the MT. Design: The Daily Hormone Study (DHS) of the Study of Women’s Health Across the Nation (SWAN) included 848 women aged 43–53 yr at baseline who collected daily urine for one cycle or up to 50 d annually for 3 yr. Main Outcome Measures: LH, FSH, estrone conjugates, and pregnanediol glucuronide levels were assessed. Cycles were classified by presumed luteal (ovulatory) status and bleeding. Hormones were related to time in study, age, menopausal status, and selected variables. Results: Ovulatory-appearing cycles declined from 80.9% at baseline to 64.7% by the third assessment (H3). Cycles presumed anovulatory and not ending with bleeding by 50 d (anovulatory/nonbleeding) increased from 8.4 to 24% by H3 and were associated with progress to early perimenopause [odds ratio (OR) = 2.66; confidence interval (CI) = 1.17–6....
Zirconocene-promoted stereoselective bicyclization of 1,6- and 1,7-dienes to produce trans-zirconabicyclo[3.3.0]octanes and cis-zirconabicyclo[4.3.0]nonanes

Abstract The Zr-promoted bicyclization of 1,6- and 1,7-dienes can stereoselectively produce trans-zirconabicyclo[3.3.0]octanes and cis-zirconabicyclo[4.3.0]nonanes, respectively; these compounds can be readily converted into protonolysis, halogenolysis, and carbonylation products.
Caustic steam flooding

A laboratory study was undertaken to investigate the potential of improving tertiary oil recovery of intermediate to heavy oils by use of caustic soda as a chemical additive in waterflooding and steamflooding. Seven aspects of this study were examined. In all cases, the process was started with a fresh and similarly waterand oil-saturated sandpack. The sandpack was obtained each time by packing sieved glass beads in the range of 35 to 48 mesh size. The cases include: (1) weak caustic soda flooding (0.001 g/cm/sup 3/) of previously waterflooded sandpack followed by steamflood, (2) caustic steamflooding immediately after waterflooding the saturated sandpack, (3) a process similar to Case 2 followed by a second cycle flooding with a higher concentration (0.0015 g/cm/sup 3/) of caustic steam, (4) waterflooding a saturated sandpack followed by conventional steamflood, (5) caustic flooding of water-saturated sandpack followed by caustic steamflood, (6) cyclic steam/caustic flooding of watersaturated sandpack, and (7) determination of the optimal temperature for caustic flood. The results of these experiments showed that as a chemical additive for tertiary waterflooding and steamflooding, caustic soda substantially improved oil recovery of mildly acidic 18/sup 0/API gravity oil over conventional waterflood and steamflood.
The dilaton theorem and closed string backgrounds

Abstract The zero-momentum ghost-dilaton is a non-primary BRST physical state present in every bosonic closed string background. It is given by the action of the BRST operator on another state |χ〉 but remains nontrivial in the semirelative BRST cohomology. When local coordinates arise from metrics we show that dilaton and |χ〉 insertions compute Riemannian curvature and geodesic curvature respectively. A proper definition of a CF T deformation induced by the dilaton requires surface integrals of the dilaton and line integrals of |λ〉 Surprisingly, the ghost number anomaly makes this a trivial deformation. While dilatons cannot deform conformal theories, they actually deform conformal string backgrounds, showing in a simple context that a string background is not necessarily the same as a CFT. We generalize the earlier proof of quantum background independence of string theory to show that a dilaton shift amounts to a shift of the string coupling in the field-dependent part of the quantum string action. Thus the “dilaton theorem”, familiar for on-shell string amplitudes, holds off-shell as a consequence of an exact symmetry of the string action.
Enantioselective Protonation of Catalytically Generated Chiral Enolates as an Approach to the Synthesis of α-Chloroesters

Treatment of α,α-dichloroaldehydes with various phenols in the presence of chiral triazolium salt catalysts and excess base results in the synthesis of α-chloro aryl esters in good yield and enantioselectivity. The reaction is tolerant of various functionality on the aldehyde as well as several electronically diverse phenols. The product chloroesters were further transformed into chloroacid, chlorohydrin, and azidoesters with nearly complete retention of enantioselectivity.
Distributed power allocation and scheduling for parallel channel wireless networks

In this paper we develop distributed approaches for power allocation and scheduling in wireless access networks. We consider a model where users communicate over a set of parallel multi-access fading channels, as in an orthogonal frequency division multiple access (OFDMA) system. At each time, each user must decide which channels to transmit on and howto allocate its power over these channels. We give distributed power allocation and scheduling policies, where each user's actions depend only on knowledge of their own channel gains. Assuming a collision model for each channel, we characterize an optimal policy which maximizes the system throughput and also give a simpler sub-optimal policy. Both policies are shown to have the optimal scaling behavior in several asymptotic regimes.
Planar Radial Spots in a Three-Component FitzHugh–Nagumo System

Localized planar patterns arise in many reaction-diffusion models. Most of the paradigm equations that have been studied so far are two-component models. While stationary localized structures are often found to be stable in such systems, travelling patterns either do not exist or are found to be unstable. In contrast, numerical simulations indicate that localized travelling structures can be stable in three-component systems. As a first step towards explaining this phenomenon, a planar singularly perturbed three-component reaction-diffusion system that arises in the context of gas-discharge systems is analysed in this paper. Using geometric singular perturbation theory, the existence and stability regions of radially symmetric stationary spot solutions are delineated and, in particular, stable spots are shown to exist in appropriate parameter regimes. This result opens up the possibility of identifying and analysing drift and Hopf bifurcations, and their criticality, from the stationary spots described here.
Growth in post-Soviet Russia: A tale of two transitions

Abstract In the early stages of post-Soviet Russia's economic transition, small-scale entrepreneurial activity appeared to be a strong engine of growth. Moreover, striking regional variations in initial conditions and adopted policy reforms appeared useful in accounting statistically for observed regional variations in entrepreneurial activity. Here, we investigate whether these relationships have persisted as Russia's transition has continued to evolve, and find that they have not. We then document that the emergence of bank-issued credit, virtually non-existent outside of Moscow prior to 2000, has been an important engine of growth since 2000. Thus to date, Russia's post-Soviet development appears as a tale of two distinct transition paths.
Government Turnover in Parliamentary Democracies

In this paper we consider a dynamic model of government formation and termination in parliamentary democracies that accounts for the following phenomena: (1) Cabinet terminations due to replacement or early election (2) Cabinet reshuf∞es (3) Minority and Surplus governments; (4) the relative instability of minority governments.
Heavy-quark correlations in deep inelastic scattering

Abstract We discuss some results for heavy quark correlations in next-to-leading order in deep inelastic electroproduction.
Zeta function regularization in de Sitter space: The Minkowski limit

We study an integral representation for the zeta function of the one-loop effective potential for a minimally coupled massive scalar field in D-dimensional de Sitter space–time. By deforming the contour of integration we present it in a form suitable for letting the de Sitter radius tend to infinity, and we demonstrate explicitly for the case D=2 that the quantities ζ(0) and ζ′(0) have the appropriate Minkowski limits.
Exact asymptotics of minimax Bahadur risk in Lipschitz regression

The estimation problem for a Lipschitz regression at a point is studied. The exact limiting performance of the Bahadur risk is found in the minimax sense, the asymptotics being presented in the explicit form in terms of the Chernoff function.
The Effects of Corporate Governance and Institutional Ownership Types on Corporate Social Performance

The effects of institutional investor types and governance devices on two dimensions of corporate social performance (CSP) were examined. Pension fund equity was positively related to both a people (women and minorities, community, and employee relations) and a product quality (product and environment) dimension of CSP, but mutual and investment bank funds exhibited no direct relationship with CSP. Outside director representation was positively related to both CSP dimensions. Top management equity was positively related to the product quality dimension but unrelated to the people dimension of CSP.
The design of a low cost video graphics terminal

We have designed and built a computer terminal that provides low cost, high quality graphics and programmable text processing by taking advantage of the latest memory and microprocessor technology. A microprocessor control element allows most of the control functions to be programmed so that all of the control electronics require less than 100 integrated circuits. The graphic image is generated by a microprocessor which accepts vector commands intended for a Tektronix storage tube display terminal. The microprocessor maps those vector commands into a random access memory, and the resulting bit map of the graphic image is displayed on a standard TV monitor. Reasonable resolution in the graphic image requires a large number of bits in the bit map, but with the use of 4K memory chips, less than 100 integrated circuits are required for the bit map memory in our design. At 1975 small-quantity prices, the parts cost for the terminal is approximately $2000.
In Situ End-Labeling of Human Testicular Tissue Demonstrates Increased Apoptosis in Conditions of Abnormal Spermatogenesis

Objective: To determine, using an in situ end-labeling technique, whether the frequency of apoptosis is increased in testis biopsy specimens that demonstrate abnormal spermatogenesis. Design: Immunohistochemical analysis was performed on archived paraffin-embedded testis biopsy specimens. Apoptotic indices, defined as the number of apoptotic bodies per the total number of cells or the number of Sertoli cells, were calculated after counting all the intratubular spermatogenic cells and Sertoli cells in 20 tubules. Setting: Major academic male factor infertility clinic. Patient(s): Forty-eight testis biopsy specimens were obtained for routine clinical purposes from 38 men with azoospermia or severe oligozoospermia. Intervention(s): In situ end-labeling was performed on archived paraffin-embedded testis biopsy specimens using terminal deoxynucleotidyl transferase. Main Outcome Measure(s): Apoptotic indices. Result(s): Significantly increased apoptotic indices were observed in patients with spermato-cyte arrest, spermatid arrest, and hypospermatogenesis compared with patients with normal spermatogenesis and the Sertoli cell-only pattern. Conclusion(s): In situ end-labeling of testis biopsy specimens from infertile men demonstrates increased apoptosis in maturation arrest and hypospermatogenesis states compared with normal spermatogenesis and the Sertoli cell-only pattern. This unique observation implicates a prominent role for this form of programmed cell death in the pathophysiology of maturation arrest and hypospermatogenesis states.
Transient multiphase processes during the explosive eruption of basalt through a geothermal borehole (Námafjall, Iceland, 1977) and implications for natural volcanic flows

Abstract Experimental and numerical studies have shown that vertical flows of gas–particle mixtures are characterized by transient behavior, with development of waves of high particle concentration separated by regions of relatively clean gas. In contrast, most models of explosive flow in volcanic conduits either treat the multiphase mixture as a single fluid (pseudo-fluid approximation) and/or assume steady flow, thereby eliminating the potential for time-dependent effects related to multiphase dynamics. The 8 September 1977 explosive eruption of basaltic tephra through a geothermal borehole (Namafjall, Iceland) provides a unique test case for multiphase volcanic processes, given that its vertical extent (∼ 1 km) is similar to that of natural volcanic conduits and its geometry is exactly known. We model this eruption by solving separate, time-dependent governing equations for conservation of mass, momentum, and energy of the gas and particle phases, allowing for drag and heat transfer between the phases. Model results are consistent with the development of transient waves of high particle concentration that propagate up the borehole, resulting in complex compressible flow phenomena along with ejection of particles in pulses in a manner that is consistent with observations at Namafjall. These transient processes occur even though the influx of gas and particles at the base of the borehole is treated as constant. Our results indicate that transient multiphase behavior is likely to be common in volcanic conduit flows, and that a key topic of future research is quantifying the types of time-dependent behaviors and their impacts on eruption column dynamics.
Federal trade commission regulation of food advertising to children: possibilities for a reinvigorated role.

Growing awareness of the role that food and beverage advertising plays in the epidemic of childhood obesity has prompted calls for stricter oversight of adver- tising practices. The food and beverage industries have taken voluntary steps in this direction, but many commentators have called for increased government regulation. The mission of the Federal Trade Commission (FTC) makes it an obvious candidate to lead a new regulatory effort. However, the FTC has a troubled history in the area of children's advertising regulation, and several political and legal factors constrain its ability to act. This article reviews those obstacles as well as the opportunities that exist at present to expand FTC oversight of food advertising to children. The FTC has considerable latitude to regulate individual food advertisements more rigorously, either on the basis that they are deceptive or on the basis that they are unfair. Broader rule making under the unfairness authority would require congressional intervention to expand the FTC's scope of authority, but there exist possibilities for rule making under the deception doctrine. Finally, the FTC could strengthen its efforts to encour- age the food industry to regulate its own advertising practices more stringently and could provide mechanisms for making voluntary initiatives more meaningful.
Satellite Drag Uncertainties Associated with Atmospheric Parameter Variations at Low Earth Orbits

An uncertainty quantification and sensitivity analysis computational technique based on the Monte Carlo method has been used for CubeSat drag studies for exploring issues in satellite decommissioning. These studies included computational simulations for altitudes of 100 and 400 km using the Hypersonic Aerothermodynamic Particle code, a direct simulation Monte Carlo solver with uncertainty quantification and sensitivity analysis capabilities allowing for variation of the solver input quantities, propagation of the input parameter variations through the model, and prediction of output uncertainties, all in an automated manner. Satellite atmospheric drag was identified as the main parameter of interest because uncertainty in drag may alter the satellite orbit and influence its lifespan. This study considers relative contributions of the input and model parameter uncertainties to the resulting satellite drag uncertainty, which enable reduction of the initial parameter space to a few major contributors; these ...
Synthesis and characterization of a pyridine adduct of bis(irontetracarbonyl)germanium(IV)

The reaction of [(CO) 4 FeGeBr 2 ] 2 ( 1 ) with Na 2 Fe(CO) 4 ( 2 ) in the presence of pyridine results in the formation of [{(CO) 4 Fe} 2 Ge·2py] ( 3 ) in high yield. A single crystal X-ray diffraction study of 3 reveals that the local environment around germanium is severely distorted from tetrahedral coordination.
Highly Diastereoselective Pd-Catalyzed Carboetherification Reactions of Acyclic Internal Alkenes. Stereoselective Synthesis of Polysubstituted Tetrahydrofurans

A highly diastereoselective synthesis of substituted tetrahydrofurans bearing stereocenters at C2 and C1′ via Pd-catalyzed carboetherification reactions of acyclic internal alkenes is described. Use of an improved catalyst composed of Pd2(dba)3/S-Phos provides products with up to >20:1 dr. The stereoselective preparation of tetrahydrofurans containing three stereocenters, including a molecule structurally related to simplakidine A, is also reported.
Forecasting turning points in international output growth rates using Bayesian exponentially weighted autoregression, time-varying parameter, and pooling techniques

Abstract In this paper two variants of an autoregressive, leading indicator (ARLI) model are employed to forecast turning points in the growth rates of 18 countries' annual real output for the years 1974–1986. Bayesian predictive densities have been employed to compute probabilities of downturns and upturns, and they have been employed in a Bayesian decision-theoretic framework to obtain optimal turning point forecasts. Various versions of the ARLI model, with and without pooling of data across countries, produced about 70 to 80 percent correct forecasts for 158 turning points. Time-varying parameter models performed slightly better than others. The performance of the ARLI models in forecasting turning points is shown to be considerably better than that of four naive methods of forecasting turning points.
N = 1 dual string pairs and gaugino condensation

Abstract We study a class of four-dimensional N = 1 heterotic string theories which have non-trivial quantum dynamics arising from asymptotically free gauge groups. These models are obtained by orbifolding 4d N = 2 heterotic/type II dual pairs by symmetries which leave unbroken products of non-abelian gauge groups (without charged matter) in a “hidden sector” on the heterotic side. Such models are expected to break supersymmetry through gaugino condensation in the hidden sector. We find a dual description of the effects of gaugino condensation on the type II side, where the corresponding superpotential arises at tree level. We speculate that the conformal field theory underlying the type II description may be related to a class of geometrical non-supersymmetric string compactifications.
Operator product expansions in the two-dimensional O(N) non-linear sigma model

Abstract The short-distance singularity of the product of a composite scalar field that deforms a field theory and an arbitrary composite field can be expressed geometrically by the beta functions, anomalous dimensions, and a connection on the theory space. Using this relation, we compute the connection perturbatively for the O( N ) non-linear sigma model in two dimensions. We show that the connection becomes free of singularities at zero temperature only if we normalize the composite fields so that their correlation functions have well-defined limits at zero temperature.
Palaeosecular variation recorded by lava flows over the past five million years

We present a new global palaeomagnetic database, comprising lava flows and thin intrusive bodies, suitable for studying palaeosecular variation and the time-averaged field. The database is presented in some detail in the appendix and is available on-line from the authors. We review palaeosecular variation models to date, emphasizing the assumptions required and the rather arbitrary construction of many of these models. Preliminary studies of the statistical properties of the new database suggest that existing palaeosecular variation models are inadequate to explain the long-term temporal variations in the field. It is increasingly apparent that data distribution and quality are pivotal in determining the characteristics of the secular variation. The work presented here demonstrates the need for revised models of the time-averaged field structure for both normal and reverse polarities before reliable models for palaeosecular variation can be made.
How much Do Decoupled Payments Affect Production? An Instrumental Variable Approach with Panel Data

How much decoupled payments, such as direct payments in the U.S., affect agricultural production remains an open empirical question with implications for policy. Using data from multiple years of the Census of Agriculture, we exploit a provision of the 2002 Farm Act that departed from previous policy by making oilseeds eligible for direct payments, thus increasing payments to areas that historically produced more oilseeds. Our instrumental variable estimates, in contrast to OLS estimates, suggest that changes in payments over the period 2002 to 2007 had little effect on aggregate production at the ZIP-code level. Copyright 2012, Oxford University Press.
Pd(II)-Catalyzed Cross-Coupling of sp3 C−H Bonds with sp2 and sp3 Boronic Acids Using Air as the Oxidant

O-Methyl hydroxamic acids, readily available from carboxylic acids, are found to be extremely reactive for β-C−H activation by Pd(OAc)2. This reactivity is exploited to develop the first example of cross-coupling sp3 C−H bonds with sp3 boronic acids. Air was shown to be a suitable stoichiometric oxidant for the catalytic oxidative coupling reaction. A biologically active natural product is readily converted to its novel analogues through this coupling reaction.
Riemannian Consensus for Manifolds With Bounded Curvature

Consensus algorithms are popular distributed algorithms for computing aggregate quantities, such as averages, in ad-hoc wireless networks. However, existing algorithms mostly address the case where the measurements lie in Euclidean space. In this work we propose Riemannian consensus, a natural extension of existing averaging consensus algorithms to the case of Riemannian manifolds. Unlike previous generalizations, our algorithm is intrinsic and, in principle, can be applied to any complete Riemannian manifold. We give sufficient convergence conditions on Riemannian manifolds with bounded curvature and we analyze the differences with respect to the Euclidean case. We test the proposed algorithms on synthetic data sampled from the space of rotations, the sphere and the Grassmann manifold.
Investigation of wear phenomena by microscopy

The various wear mechanisms involved in the loss of material from metallic and nonmetallic surfaces are discussed. The results presented indicate how various microscopy techniques used in conjunction with other analytical tools can assist in the elucidation of a wear mechanism. Without question, microscopy is the single most important tool for the study of the wear of surfaces, to assess and address inherent mechanisms of the material removal process.
The relationship between risk and capital in commercial banks

Abstract This study investigates the relationship between changes in risk and capital in a large sample of banks. A positive association between changes in risk and capital is found. The fact that this finding holds in banks with capital ratios in excess of regulatory minimum levels supports the conclusion that, for most banks, bank owners' and/or managers' private incentives work to limit total risk exposure. Results for banks which were undercapitalized by regulatory standards indicate that regulation was at least partially effective during the period covered. Overall, the findings support a conclusion that changes in bank capital over the period studied have been ‘risk-based’.
Transitions in Defense Management Reform: A Review of the Government Accountability Office’s Chief Management Officer Recommendation and Comments for the New Administration

The Government Accountability Office believes the answer to the U.S. Defense Department’s persistent management problems is to be found in the creation of a new position, chief management officer, to oversee defense business transformation. The recommendation for this position is reviewed and used to raise questions and spur inquiry in the areas of evidence-based reform, the relationship between policy and administration, auditor overreach, and sustaining reforms through transition. The latter portion is expanded in this time of transition, and recommendations are made to the new administration to develop a management agenda, to the defense career executives to facilitate the transition, and to the next comptroller general to consider how the Government Accountability Office’s varied roles produce outputs that align with the desired outcomes in both the policy and administration domains.
A Limit from the X-Ray Background on the Contribution of Quasars to Reionization

A population of black holes (BHs) at high redshifts (z 6) that contributes significantly to the ionization of the intergalactic medium (IGM) would be accompanied by the copious production of hard (10 keV) X-ray photons. The resulting hard X-ray background would redshift and be observed as a present-day soft X-ray background (SXB). Under the hypothesis that BHs are the main producers of reionizing photons in the high-redshift universe, we calculate their contribution to the present-day SXB. We find that accreting BHs with a hard spectrum (be it luminous quasars or their lower mass "miniquasar" counterparts) could not fully reionize the universe without saturating the unresolved component of the 0.5-2 keV SXB at the ≥2 σ level. Distant miniquasars that produce enough X-rays to only partially ionize the IGM to a level of at most xe ~ 50% saturate the unresolved SXB by 1 σ. Improved determinations of the unresolved component of the SXB can provide a powerful constraint on the contribution of accreting BHs to partial or full reionization.
Anion-π interactions

This tutorial review provides an overview of the theoretical and experimental investigations that resulted in the recognition of anion-π interactions, i.e., non-covalent forces between electron deficient aromatic systems and anions. Several pioneering theoretical studies revealed that these interactions are energetically favorable (∼20–50 kJ mol–1). Anion-π interactions are gaining significant recognition, and their pivotal role in many key chemical and biological processes is being increasingly appreciated. The design of highly selective anion receptors and channels represent important advances in this nascent field of supramolecular chemistry.
MEMS tunable gratings with analog actuation

We have designed and fabricated tunable gratings with period tunable to within fraction of a nanometer. We actuated the gratings by electrostatic and piezoelectric means, and demonstrated period changes of order 1 nm. Fabrication processes for the two versions are presented. Devices characterization and experimental results are given for respective devices.
Principles of Adaptive Optics

History and Background: Introduction. History. Physical Optics: Propagation with Aberrations. Imaging with Aberrations. Representing the Wavefront. Interference. Adaptive Optics Terms. Sources of Aberrations: Atmospheric Turbulence: Descriptions of Atmospheric Turbulence. Refractive Index Structure Constant. Turbulence Effects. Turbulence MTF. Thermal Blooming: Blooming Strength and Critical Power. Turbulence, Jitter, and Thermal Blooming. Non-atmospheric Sources: Optical Misalignments and Jitter. Thermally Induced Distortions of Optics. Manufacturing and Microerrors. Other Sources of Aberrations. Adaptive Optics Compensation: Phase Conjugation. Limitations of Phase Conjugation: Turbulence Spatial Error. Turbulence Temporal Error. Sensor Noise Limitations. Thermal Blooming Compensation. Artificial Guide Stars. Combining the Limitations. Linear Analysis of Random Wavefronts. Linear Analysis of Deterministic Wavefronts: Partial Phase Conjugation. Adaptive Optics Systems: Adaptive Optics Imaging Systems. Beam Propagation Systems: Local Loop Beam Cleanup Systems. Alternative Concepts. Pros and Cons of the Various Approaches. Unconventional Adaptive Optics: Nonlinear Optics. Elastic Photon Scattering, DFWM. Inelastic Photon Scattering. System Engineering. Wavefront Sensing: Directly Measuring Phase: The Non-uniqueness of the Diffraction Pattern. Determining Phase Information from Intensity. Modal and Zonal Sensing. Direct Wavefront Sensing--Modal: Importance of Wavefront Tilt. Measurement of Tilt. Focus Sensing. Modal Sensing of Higher-Order Aberrations. Direct Wavefront Sensing--Zonal: Interferometiric Wavefront Sensing. Hartman Wavefront Sensors. Curvature Sensing. Selecting a Method. Indirect Wavefront Sensing Methods: Multidither Adaptive Optics. Image Sharpening. Wavefront Sampling: Beamsplitters. Hole Gratings. Temporal Duplexing. Reflective Wedges. Diffraction Gratings. Hybrids. Sensitivities of Sampler Concepts. Detectors and Noise. WavefrontCorrection: Modal Tilt Correction. Modal Higher-Order Correction. Segmented Mirrors. Deformable Mirrors: Actuation Techniques. Actuator Influence Functions. Bimorph Corrector Mirrors. Membrane and Micromachine Mirrors. Edge Actuated Mirrors. Large Correcting Optics. Special Correction Devices: Liquid Crystal Phase Modulators. Spatial Light Modulators. Charged-large-array-mirrors. Reconstruction and Controls: Introduction. Single-Channel Linear Control: Fundamental Control Tools. Transfer Functions. Proportional Control. First- and Second-Order Lag. Feedback. Frequency Response of Control Systems. Digital Controls. Multivariate Adaptive Optics Controls: Solution of Linear Equations. Direct Wavefront Reconstruction: Phase from Wavefront Slopes. Modes from Wavefront Slopes. Phase from Wavefront Modes. Modes from Wavefront Modes. Zonal Corrector from Continuous Phase. Modal Corrector from Continuous Phase. Zonal Corrector from Modal Phase. Modal Correctors from Modal Phase. Indirect Reconstructions.Modal Corrector from Wavefront Modes. Zonal Corrector from Wavefront Slopes. Spatiotemporal Considerations. Subject Index.
Newton-Hodge filtration for self-dual F-crystals

In this paper we study F-crystals with self-dual structure over base schemes of characteristic p. We generalize Katz's Newton-Hodge Filtration Theorem to F-crystals with self-dual structure. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Will electronic principles make possible a business revolution

I am very appreciative of the opportunity which your committee has afforded to me to speak to this great audience of scientists, engineers and business people attending the 1954 Western Computer Conference. You gentlemen have accomplished much in a relatively short time. You will accomplish even more in the future.
A Note on Ranking Real Estate Research Journals

An understanding of how thirty real estate journals are perceived for promotion and tenure and for professional applicability was sought by surveying members of the two most important real estate academic organizations. Several subgroup comparisons were made revealing some common perceptions but a significant amount of disagreement as well. Among findings robust across the surveyed community were that the Journal of the American Real Estate and Urban Economics Association (changed to Real Estate Economics in 1995) is the most important outlet for promotion and tenure and the Appraisal Journal is the most important outlet for professional applicability. Two distinct journal groupings emerged: an academic group composed of eight journals and a professional group of twenty.
Environmental Challenges for 45-nm and 32-nm node CMOS Logic

The objective of this work is to understand the materials and energy requirements, and emissions associated with new semiconductor manufacturing technology nodes. Current and near-future CMOS technologies (for the 45-nm and 32-nm nodes) are investigated using an inventory based on bottom-up process data. The process flow of the CMOS chip is modeled by updating an existing inventory analysis (for 130 nm node devices) to include strained Si channels, metal gates, 10 layers of interconnect and high-k gate dielectrics used in 45-nm and 32-nm CMOS nodes. Conclusions are made concerning emissions of new materials and trends in life cycle energy consumption of logic devices.
The DoF of the asymmetric MIMO interference channel with square direct link channel matrices

This paper studies the sum Degrees of Freedom (DoF) of K-user asymmetric MIMO Interference Channel (IC) with square direct link channel matrices, that is, the u-th transmitter and its intended receiver have M u ∊ N antennas each, where M u need not be the same for all u ∊ [1 : K]. Starting from a 3-user example, it is shown that existing cooperation-based outer bounds are insufficient to characterize the DoF. Moreover, it is shown that two distinct operating regimes exist. With a dominant user, i.e., a user that has more antennas than the other two users combined, it is DoF optimal to let that user transmit alone on the IC. Otherwise, it is DoF optimal to decompose and operate the 3-user MIMO IC as an (M 1 + M 2 + M 3 )-user SISO IC. This indicates that MIMO operations are useless from a DoF perspective in systems without a dominant user. The main contribution of the paper is the derivation of a novel outer bound for the general K-user case that is tight in the regime where a dominant user is not present; this is done by generalizing the insights from the 3-user example to an arbitrary number of users.
How light can the higgs be

Abstract It is widely believed that, for a given Top mass, the Higgs mass has a lower bound: if mHiggs is too small, the Higgs vacuum is unstable due to Top dynamics. From vacuum instability, the state-of-the-art calculation of the lower bound is close to the current experimental limit. Using non-perturbative simulations and large N calculations, we show that the vacuum is in fact never unstable. Instead, we investigate the existence of a new lower bound, based on the intrinsic cut-off of this trivial theory.
Ectopic pregnancy and reproductive technology.

The frequency of ectopic pregnancy has approximately tripled in each of the last two decades1,2and is currently See also p 1823. reaching epidemic proportions in the United States and the United Kingdom.3At the University of California, San Francisco, Hospitals, the rate of ectopic pregnancy has paralleled this trend, increasing from one per 123 live births to one per 36 live births during the past ten years.4As in other epidemics, physicians and public health professionals have two primary responsibilities: (1) to provide timely and effective care to women afflicted with tubal pregnancy and (2) to ascertain the causes of this escalating problem, so that appropriate preventive measures can be instituted to eradicate this fertility-compromising and potentially life-threatening condition. The responsibilities of physicians were summarized perceptively by Dr Bernard Rieux, the narrator of Camus' classic novel,The Plague, who dispassionately and selflessly battled a plague epidemic