cssi/SciSciGPT-SciSciNet huggingface dataset:
P(MeNCH2CH2)3N: an efficient catalyst for the desilylation of tert-butyldimethylsilyl ethers

tert-Butyldimethylsilyl (TBDMS) ethers of primary, secondary, and tertiary alcohols and phenolic TBDMS ethers are desilylated to their corresponding alcohols and phenols, respectively, in DMSO, at 80 °C, in 68−94% yield in the presence of 0.2−0.4 equiv of P(MeNCH2CH2)3N. Using P(i-PrNCH2CH2)3N as the catalyst, 85−97% yields of desilylated alcohols were obtained from TBDMS ethers of 1-octanol, 2-phenoxyethanol, and racemic α-phenyl ethanol. These are the first examples of desilylations of silyl ethers catalyzed by nonionic bases. Both catalysts were much less effective for the desilylation of tert-butyldiphenylsilyl (TBDPS) ethers (22−45% yield) under the same conditions as used for TBDMS ethers. Possible pathways involving nucleophilic attack of the anion of the solvent molecule (generated by the catalyst) at the Si−O bond of silyl ether or a prior activation of the silyl ether by the catalyst via a P−Si interaction followed by nucleophilic attack of the solvent anion are proposed on the basis of 1H and 3...
Mitochondrial division in rat cardiomyocytes: an electron microscope study.

In cardiomyocytes of rats, two distinct mitochondrial division processes are in operation. The predominant process involves extension of a single crista until it spans the full width of a mitochondrion. Ingrowth of the outer membrane ultimately results in scission. The second division process involves “pinching”, in which narrowing of the organelle at specific surface locations leads to its attenuation. When limiting membranes from opposite sides meet, mitochondrial fission ensues. When pinching is the operative mode, elements of sarcoplasmic reticulum always are associated with the membrane constrictions. The nuclear control mechanisms that determine which modality of mitochondrial division will prevail are unknown.
Chiral Symmetry from Type IIA Branes

We propose a mechanism in which, using an 8-brane, a 6-brane ends on an NS-brane in type IIA superstring theory. We use this mechanism to construct N = 1 supersymmetric gauge theories in four dimensions with chiral matter localized in different points in space. Anomaly cancelation for the gauge theories is satisfied by requiring RR charge conservation for the various type IIA fields. The construction allows us to study a curious phase transition in which the number of flavors in supersymmetric QCD depends on the value of the ten-dimensional cosmological constant. These phenomena are related to the fact that every time a D8-brane crosses an NS-brane, a D6-brane is created in between them.
Diagnosis of insidious data disasters

Everyone taking field observations has a story of data collection gone wrong, and in most cases, the errors in the data are immediately obvious. A more challenging problem occurs when the errors are insidious, i.e., not readily detectable, and the error-laden data appear useful for model testing and development. We present two case studies, one related to the water balance in the snow-fed Tuolumne River, Sierra Nevada, California, combined with modeling using the Distributed Hydrology Soil Vegetation Model (DHSVM); and one related to the energy balance at Snoqualmie Pass, Washington, combined with modeling using the Structure for Unifying Multiple Modeling Alternatives (SUMMA). In the Tuolumne, modeled streamflow in 1 year was more than twice as large as observed; at Snoqualmie, modeled nighttime surface temperatures were biased by about +10°C. Both appeared to be modeling failures, until detective work uncovered observational errors. We conclude with a discussion of what these cases teach us about science in an age of specialized research, when one person collects data, a separate person conducts model simulations, and a computer is charged with data quality assurance.
Hydrothermal synthesis, structure, and magnetic properties of Pu(SeO3)2

The reaction between PuO{sub 2} and SeO{sub 2} under mild hydrothermal conditions results in the formation of Pu(SeO{sub 3}){sub 2} as brick-red prisms. This compound adopts the Ce(SeO{sub 3}){sub 2} structure type, and consists of one-dimensional chains of edge-sharing [PuO{sub 8}] distorted bicapped trigonal prisms linked by [SeO{sub 3}] units into a three-dimensional network. Crystallographic data: Pu(SeO{sub 3}){sub 2}, monoclinic, space group P2{sub 1}/n, a=6.960(1) A, b=10.547(2) A, c=7.245(1) A, {beta}=106.880(9){sup o}, V=508.98(17) A{sup 3}, Z=4 (T=193 K), R(F)=2.92% for 83 parameters with 1140 reflections with I>2{sigma}(I). Magnetic susceptibility data for Pu(SeO{sub 3}){sub 2} are linear from 35 to 320 K and yield an effective moment of 2.71(5) {mu}{sub B} and a Weiss constant of -500(5) K. - Graphical abstract: A depiction of the three-dimensional structure of Pu(SeO{sub 3}){sub 2} formed from the interconnection of one-dimensional chains of edge-sharing PuO{sub 8} dodecahedra by selenite anions.
Image lightness rescaling using sigmoidal contrast enhancement functions

In color gamut mapping of pictorial images, the lightness rendition of the mapped images plays a major role in the quality of the final image. For color gamut mapping tasks, where the goal is to produce a match to the original scene, it is important to maintain the perceived lightness contrast of the original image. Typical lightness remapping functions such as linear compression, soft compression, and hard clipping reduce the lightness contrast of the input image. Sigmoidal remapping functions were utilized to overcome the natural loss in perceived lightness contrast that results when an image from a full dynamic range device is scaled into the limited dynamic range of a destination device. These functions were tuned to the particular lightness characteristics of the images used and the selected dynamic ranges. The sigmoidal remapping functions were selected based on an empirical contrast enhancement model that was developed for the result of a psychophysical adjustment experiment. The results of this study showed that it was possible to maintain the perceived lightness contrast of the images by using sigmoidal contrast enhancement functions to selectively rescale images from a source device with a full dynamic range into a destination device with a limited dynamic range.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
Light-Induced Metastable Linkage Isomers of Ruthenium Sulfur Dioxide Complexes

The irradiation of ruthenium−sulfur dioxide complexes of general formula trans-[RuII(NH3)4(SO2)X]Y with laser light at low temperature results in linkage isomerization of SO2, starting with η1-plan...
Heat mirror coatings for energy conserving windows

Abstract Heat-mirror coatings are important as transparent insulation for a host of applications, including building window glazings. They reduce thermal emittance of glass and polymeric substrates, thereby decreasing the effective radiative loss of a glazing or window assembly. Properties of coatings and substrates, as well as various window designs, are detailed. The paper reviews heat-mirror deposition technology including chemical vapor deposition using hydrolysis and pyrolysis reactions, dc and rf sputtering using reactive, biased and nonreactive techniques, vapor deposition and ion plating. The properties of single-layer films including coatings of In 2 O 3 :Sn, doped SnO 2 , Cd 2 SnO 4 , noble and transition metal films are enumerated. Multilayer films described include dielectric overcoated metals such as ZnS/metal/ZnS, Bi 2 O 3 /Au/Bi 2 O 3 and TiO 2 /Ag/TiO 2 . Electrical, solar and infrared radiative properties are tabulated. Much of the data presented is also useful for photovoltaic and collector applications. New and innovative materials systems are suggested.
Enantioselective synthesis and pharmacology of 11-hydroxy-(1'S,2'R)-dimethylheptyl-Δ8-THC

Abstract An enantioselective synthesis of the (1' S ,2' R )-dimethylheptyl cannabinoid side chain has been developed and employed in the synthesis of 11-hydroxy-(1' S ,2' R )-dimethylheptyl-Δ 8 -THC ( 3 ). Pharmacology, in vivo and in vitro, indicate ( 3 ) to be one of the most potent traditional cannabinoids known.
Optimization of offshore field development to minimize investment

Offshore oil and gas development is identified with high investment. Considerable incentive therefore exists to reduce investment and to improve field profitability. A computational method has been developed to optimize field development and to minimize investment. The solution of extremely large economic problems of this nature has not been reported previously. An integer mathematical porgraming computational tool, using a method called ''zero-one implicit enumeration,'' was developed for modeling and solving this problem. This technique allows for efficient problem solution on a computer.
On the Use of Anycast in DNS

In this paper, we measure the performance impact of anycast on DNS. We study four top-level DNS servers to evaluate how anycast improves DNS service and compare different anycast configurations. Increased availability is one of the supposed advantages of anycast and we found that indeed the number of observed outages was smaller for anycast, suggesting that it provides a mostly stable service. On the other hand, outages can last up to multiple minutes, mainly due to slow BGP convergence. We also found that anycast indeed reduces query latency. Furthermore, depending on the anycast configuration used, 37% to 80% of the queries are directed to the closest anycast instance. Our measurements revealed an inherent trade-off between increasing the percentage of queries answered by the closest server and the stability of the DNS zone, measured by the number of query failures and server switches. We believe that these findings will help network providers to deploy anycast more effectively in the future.
Inflation and non-equilibrium dynamics

Abstract Herman Feschbach is a premier nuclear physicist. Although I do no research in his physics subfield, I have found it useful to apply methods developed in that area to early universe investigations that rely on a field-theoretic description for the time evolution of pure and/or mixed initial states. On the occasion of his seventieth birthday, I offer for his enjoyment this essay in which I describe how time-dependent Hartree-Fock methods and their generalizations to mixed states are used in attempts to establish various cosmological scenarios, in particular, inflation.
A major revision of iron meteorite cooling rates—An experimental study of the growth of the Widmanstätten pattern

Abstract In this study kamacite was experimentally grown in taenite grains of Fe-Ni-P alloys containing between 5 and 10 wt% Ni and 0 and 1.0 wt% P. Both isothermal heat treatments and non-isothermal heat treatments at cooling rates of 2 to 5°C/day were carried out. Analytical electron microscopy was used to examine the orientation and chemical composition of the kamacite and the surrounding taenite matrix. The kamacite so produced is spindle or rod shaped and has a Widmanstatten pattern orientation. The presence of heterogeneous sites such as phosphides is necessary for the nucleation of the intergranular kamacite. During kamacite growth both Ni and P partition between kamacite and taenite with chemical equilibrium at the two phase interface. The growth kinetics are limited by the diffusion of Ni in taenite. Additional diffusion experiments showed that the volume diffusion coefficient of Ni in taenite is raised by a factor of 10 at 750°C in the presence of only 0.15 wt% P. A numerical model to simulate the growth of kamacite in Fe-Ni-P alloys, based on our experimental results, was developed and applied to estimate the cooling rates of the iron meteorites. The cooling rates predicted by the new model are two orders of magnitude greater than those of previous studies. For example the cooling rates of chemical groups I, IIIAB and IVA are 400–4000°C/106years, 150–1400°C/ 106 years and 750–6000°C/106years respectively. Previous models gave 1–4°C/106 years, 1–10°C/106 years and 3–200°C/106 years. Such fast cooling rates can be interpreted to indicate that meteorite parent bodies need only be a few kilometers in diameter or that iron meteorites can be formed near the surface of larger asteroidal bodies.
Generation and in situ Diels–Alder reactions of activated nitroethylene derivatives

Abstract Dienes readily undergo Diels–Alder reaction with CH2C(NO2)SO2Ph ( 2a ), CH2C(NO2)CO2Et ( 2b ), and CH2C(NO2)COPh ( 2c ), all observed in situ by 1H NMR. The cycloadducts of 2a undergo SRN1 reactions.
Performance characteristics of microcomputer Prolog implementations

In this paper we present the results of several different categories of benchmarks performed on microcomputer PROLOG interpreters and compilers. These tests were found useful in our lab in determining optimal environments for research in several different categories of non-numerical applications. The PROLOG clause sets, as well as the benchmark results, are provided.
Limitations of ion etching for interface analysis

Abstract The advantages and limitations of using ion sputtering for interfacial analysis are reviewed. It is concluded that many artifacts may degrade interfacial resolution (e.g. surface roughness, zone of mixing, bulk and surface diffusion, implantation, residual gas adsorption and matrix effects). Techniques to minimize these limitations are suggested, e.g. the use of reactive ion beams, multiple ion beams, sample rotation and special mounting, variable ion energies and incident angles, and deconvolution methods. It is concluded, however, that sputtering may destroy the atomic arrangement and chemical state information at the interface. New approaches are needed to determine these interfacial parameters and some are discussed in this paper as well as in the paper by Silcox et al.
Creating Corporate Accountability: Foundational Principles to Make Corporate Citizenship Real

This paper explores the growing array of initiatives aimed at creating corporate accountability with the goal of attempting to uncover the foundation principles that underlie them and create a “floor” below which practices are ethically questionable. Using the Global Compact's nine principles and the work of Transparency International as guides, foundational principles seem to exist in the areas of human rights, labor standards, environment, and anti-corruption initiatives.
Criteria for Core-Collapse Supernova Explosions by the Neutrino Mechanism

We investigate the criteria for successful core-collapse supernova explosions by the neutrino mechanism. We find that a critical-luminosity/mass accretion rate condition distinguishes nonexploding from exploding models in hydrodynamic one-dimensional (1D) and two-dimensional (2D) simulations. We present 95 such simulations that parametrically explore the dependence on neutrino luminosity, mass accretion rate, resolution, and dimensionality. While radial oscillations mediate the transition between 1D accretion (nonexploding) and exploding simulations, the nonradial standing accretion shock instability characterizes 2D simulations. We find that it is useful to compare the average dwell time of matter in the gain region with the corresponding heating timescale, but that tracking the residence time distribution function of tracer particles better describes the complex flows in multidimensional simulations. Integral quantities such as the net heating rate, heating efficiency, and mass in the gain region decrease with time in nonexploding models but, for 2D exploding models, increase before, during, and after explosion. At the onset of explosion in 2D, the heating efficiency is ~2%-~5% and the mass in the gain region is ~0.005 to ~0.01 M☉. Importantly, we find that the critical luminosity for explosions in 2D is ~70% of the critical luminosity required in 1D. This result is not sensitive to resolution or whether the 2D computational domain is a quadrant or the full 180°. We suggest that the relaxation of the explosion condition in going from 1D to 2D (and to, perhaps, 3D) is of a general character and is not limited by the parametric nature of this study.
Quantum generalization of the Horn conjecture

(Recall that the Lie algebra of the special unitary group SU(n) is isomorphic to the real vector space of traceless Hermitian matrices as representations of SU(n) and hence the terminology "additive eigenvalue problem" for SU(n).) In 1962, Horn [17] gave a conjectural solution to a problem equivalent to the above additive eigenvalue problem for SU(n), by a recursively determined system of inequalities. In [19], Klyachko gave a solution to the additive eigenvalue problem for SU(n) in terms of a certain system of inequalities. To write down this system, we need to know which structure constants in the cohomology of Gr(r, n) (written in the Schubert basis) 0 2 be a positive integer. Characterize the possible eigenvalues (a1, a2,..., as) of matrices A^\A^2\ ..., A? e SU(n) which satisfy A A& A^ = 1.
Periodic and solitary waves on thin, horizontal, gas-sheared liquid films

Abstract Measurements of wavelengths and speeds of periodic waves which occur at the interface of thin, horizontal, liquid films sheared by a cocurrent gas flow are compared with predictions of linear theory. In general, linear predictions accurately match the data near the point of neutral stability but begin to deviate as the gas velocity increases. The behavior away from neutral stability is explained by the examination of the dynamical system associated with steady solutions to a nonlinear wave equation based on boundary-layer approximations. Periodic waves are seen to occur in the neighborhood of the Hopf curve which serves as a boundary between periodic waves and a flat film. Solitary waves (which correspond under some circumstances to disturbance or roll waves) are observed to lie in another region of parameter space at gas velocities well above neutral stability. These results suggest that a complete nonlinear analysis of the boundary-layer (or associated wave) equations would be useful for predicting amplitudes and speeds for periodic waves and the region of occurrence for solitary waves.
How Protostellar Outflows Help Massive Stars Form

We consider the effects of an outflow on radiation escaping from the infalling envelope around a massive protostar. Using numerical radiative transfer calculations, we show that outflows with properties comparable to those observed around massive stars lead to significant anisotropy in the stellar radiation field, which greatly reduces the radiation pressure experienced by gas in the infalling envelope. This means that radiation pressure is a much less significant barrier to massive star formation than has previously been thought.
Emission of charged particles from four- and five-dimensional black holes

Abstract Recently Das and Mathur found that the leading order Hawking emission rate of neutral scalars by near-extremal D = 5 black holes is exactly reproduced by a string theoretic model involving intersecting D-branes. We show that the agreement continues to hold for charged scalar emission. We further show that similar agreement can be obtained for a class of near-extremal D = 4 black holes using a model inspired by M-theory. In this model, BPS-saturated D = 4 black holes with four charges are realized in M-theory as 5-branes triply intersecting over a string. The low-energy excitations are signals traveling on the intersection string.
The adsorption and thermal decomposition of tricresylphosphate (TCP) on iron and gold

Because tricresyl-phosphate (TCP) is a common antiwear additive in lubricants, there is great interest in its interactions with metal substrates. The TCP was allowed to adsorb on polycrystalline iron and gold at room temperature. X-ray photoelectron spectroscopy (XPS) was used to analyze the adsorbed species. The substrate was then heated in steps to 330 C, and the changes in the adsorbate were analyzed after each step. On both substrates saturation adsorption occurred at about one monolayer, but the sticking coefficient was less on gold than on iron. Comparison of the XPS spectra of TCP on each substrate with the spectrum from condensed TCP indicated nondissociative adsorption on gold, possibly by dipole-induced dipole interaction. On iron, there was apparently additional interaction between the substrate and the tolyl groups on the TCP molecule. TCP began to desorb molecularly from gold as soon as the gold was heated above room temperature. The desorption was complete by 200 C. However, when the iron substrate was heated, TCP did not desorb but decomposed between 150 and 250 C.
Proper Motion of the Crab Pulsar Revisited

It has been suggested that the Crab pulsar's proper motion is aligned with the symmetry axis of the pulsar wind nebula. We have revisited this question, examining >6 years of F547M WFPC2 chip 3 images to obtain a best-fit value of μ* = 14.9 ± 0.8 mas yr-1 at P.A. 278° ± 3°. At 26° ± 3° to the nebula axis, this substantially relaxes constraints on the birth kick of this pulsar. Such misalignment allows the momentum to be imparted over ~1 s timescales.
Quasi-commuting families of quantum minors

In [B. Leclerc, A. Zelevinsky, Quasicommuting families of quantum Plucker coordinates, in: Kirillov's Seminar on Representation Theory, in: Amer. Math. Soc. Transl. (2), vol. 181, Amer. Math. Soc., Providence, RI, 1998, pp. 85–108], a combinatorial criterion for quasi-commutativity is established for pairs of quantum Plucker coordinates in the quantized coordinate algebra Cq[F] of the flag variety of type A. This paper attempts to generalize these results by producing necessary and sufficient conditions for pairs of quantum minors in the quantized coordinate algebra Cq[Matk×m] to quasi-commute. In addition, we study the combinatorics of maximal (by inclusion) families of pairwise quasi-commuting quantum minors and pose relevant conjectures.
Hypothesis Testing for Resolving Integer Ambiguity in GPS

: This paper presents statistical techniques for validating integer ambiguities and detecting cycle slips. The multiple-hypothesis Wald sequential probability ratio test (SPRT) validates the choice of initial integer ambiguities by finding the conditional probability that each set of integer biases under consideration is the true bias condition. The multiple-hypothesis Shiryayev SPRT monitors for cycle slips by determining the conditional probability that the integer biases have jumped from the nominal bias condition to each member of a collection of other bias conditions. Both tests use a geometric combination of the carrier-phase measurements and the difference between the carrier-phase measurements and code measurements as measurement residuals. Because the SPRT calculations operate on the probability density functions of these measurement residuals, they can correctly compensate for non-Gaussian measurement errors, such as multipath. The efficacy of our techniques is demonstrated by results from simulations and field experiments.
Helioseismological Implications of Recent Solar Abundance Determinations

We show that standard solar models are in good agreement with the helioseismologically determined sound speed and density as a function of solar radius, the depth of the convective zone, and the surface helium abundance, as long as those models do not incorporate the most recent heavy-element abundance determinations. However, sophisticated new analyses of the solar atmosphere infer lower abundances of the lighter metals (like C, N, O, Ne, and Ar) than the previously widely used surface abundances. We show that solar models that include the lower heavy-element abundances disagree with the solar profiles of sound speed and density as well as the depth of the convective zone and the helium abundance. The disagreements for models with the new abundances range from factors of several to many times the quoted uncertainties in the helioseismological measurements. The disagreements are at temperatures that are too low to affect significantly solar neutrino emission. If errors in the calculated OPAL opacities are solely responsible for the disagreements, then the corrections in the opacity must extend from 2 × 106 K (R = 0.7 R☉) to 5 × 106 K (R = 0.4 R☉), with opacity increases of the order of 10%.
Major lunar crustal terranes: Surface expressions and crust‐mantle origins

In light of global remotely sensed data, the igneous crust of the Moon can no longer be viewed as a simple, globally stratified cumulus structure, composed of a flotation upper crust of anorthosite underlain by progressively more mafic rocks and a residual-melt (KREEP) sandwich horizon near the base of the lower crust. Instead, global geochemical information derived from Clementine multispectral data and Lunar Prospector gamma-ray data reveals at least three distinct provinces whose geochemistry and petrologic history make them geologically unique: (1) the Procellarum KREEP Terrane (PKT), (2) the Feldspathic High-lands Terrane (FHT), and (3) the South Pole-Aitken Terrane (SPAT). The PKT is a mafic province, coincident with the largely resurfaced area in the Procellarum-Imbrium region whose petrogenesis relates to the early differentiation of the Moon. Here, some 40% of the Th in the Moon's crust is concentrated into a region that constitutes only about 10% of the crustal volume. This concentration of Th (average ∼5 ppm), and by implication the other heat producing elements, U and K, led to a fundamentally different thermal and igneous evolution within this region compared to other parts of the lunar crust. Lower-crustal materials within the PKT likely interacted with underlying mantle materials to produce hybrid magmatism, leading to the magnesian suite of lunar rocks and possibly KREEP basalt. Although rare in the Apollo sample collection, widespread mare volcanic rocks having substantial Th enrichment are indicated by the remote data and may reflect further interaction between enriched crustal residues and mantle sources. The FHT is characterized by a central anorthositic region that constitutes the remnant of an anorthositic craton resulting from early lunar differentiation. Basin impacts into this region do not excavate significantly more mafic material, suggesting a thickness of tens of kilometers of anorthositic crust. The feldspathic lunar meteorites may represent samples from the anorthositic central region of the FHT. Ejecta from deep-penetrating basin impacts outside of the central anorthositic region, however, indicate an increasingly mafic composition with depth. The SPAT, a mafic anomaly of great magnitude, may include material of the upper mantle as well as lower crust; thus it is designated a separate terrane. Whether the SPA basin impact simply uncovered lower crust such as we infer for the FHT remains to be determined.
An energy-aware relay selection scheme for ALLIANCES

ALLIANCES is a newly proposed wireless MAC protocol that exploits the cooperation of source nodes and relay nodes to resolve collisions and further improve throughput. A relay selection scheme is a significant piece of ALLIANCES, directly affecting the throughput and the energy distribution. Previously researchers have proposed a location relay selection scheme (LRS); this scheme selects the best relay nodes based on the location of each node. LRS greatly improves the network's throughput compared to the random relay selection scheme (RRS); however, LRS does not take into account energy, which is the most precious commodity of mobile communication. In this paper, we propose an energy-aware relay selection scheme (ERS); ERS maintains the performance benefits of LRS, but more evenly distributes the amount to energy remaining throughout the network. Simulation results show that ERS provides 24.3% longer lifetime of the network than LRS, without a noticeable throughput degradation.
Synthesis of symmetrical trisubstituted olefins by cross metathesis.

Trisubstituted alkenes have been prepared via intermolecular olefin cross-metathesis (CM) between α-olefins and symmetrically 1,1-disubstituted olefins using an imidazolylidene ruthenium benzylidene complex. Of particular interest is the synthesis of isoprenoid/prenyl groups by a simple solvent-free CM reaction with isobutylene. In addition, prenyl groups can also be installed by a cross-metathesis of 2-methyl-2-butene with a variety of α-olefins at room temperature with low catalyst loadings.
A Reiterative Approach to 2,3-Disubstituted Naphthalenes and Anthracenes

[reaction: see text] Simple bis(bromoethynyl)arenediynes are easily prepared by the desilylative halogenation of the corresponding trimethylsilyl derivatives. Cycloaromatization of these halogenated enediynes leads to the otherwise difficult to prepare 2,3-dibromoarenes in good yield. Alkynylation of the resulting haloaromatic compound regenerates the soluble enediyne system, homologated by one aromatic ring. This iterative methodology can be terminated by the cycloaromatization of the unsubstituted enediyne, providing the simple acene hydrocarbon.
Recent advances in our understanding of the vitamin D endocrine system.

An investigation into the metabolism and function of vitamin D from 1962 to the present time has led to the discovery that vitamin D does not act directly but must be metabolically altered. A pursuit of this investigation has led to the discovery of a new endocrine system which uses vitamin D as its building block to form at least one calcium and phosphorus mobilizing hormone, 1,25—(OH)2D3. This hormone is formed exclusively in the kidney and has its function in intestine and bone, and perhaps kidney. Further study of the mechanism whereby this endocrine system is regulated and the influence of the forms of vitamin D on the target organs has led to the use of the information and of the hormonal form of vitamin D in the treatment of a variety of metabolic bone diseases. This new steroid hormone system then represents an important contribution of basic science investigation to the practice of medicine and to the well being of mankind.
Use Of The Smartt Interferometer As An Alignment Tool For Infrared Laser Systems

The ability to minimize the pointing and focusing errors at the focal plane is crucial in many applications involving infrared laser systems. This is particularly the case for systems involving multiple beams reaching the focal plane, as in the case of the LASL CO2 laser fusion systems. For example, the LASL Helios CO2 Laser Fusion System has eight 34-cm diameter beams each with an f number of approximately 2.4 coming to focus, the last element being an off-aperture parabola with a focal length of approximately 77.3 cm. The design tolerance for pointing accuracy is ± 25 microns and for focusing accuracy is ± 50 microns for the Helios system. The Smartt interferometer shows promise of not only evaluating the optical quality of the beam, but it can be used to align the beam to the tolerance levels stated above. This paper describes the procedure, as well as experimental results obtained, which show that pointing accuracies of ±12.5 microns and focusing accuracies of ±25 microns are obtained at the focus of a CO2 laser beam in a setup which duplicates the target region of the Helios CO2 Laser Fusion System. The backlash in the x-y-z stage micrometer used in the experiment is estimated to be 10 microns, though precautions were taken to move in the same direction throughout an experimental run.© (1979) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
Goals of the ARISE Space VLBI Mission

Abstract Supermassive black holes, with masses of 10 6 M ⊙ to more than 10 9 M ⊙ , are among the most spectacular objects in the Universe, and are laboratories for physics in extreme conditions. The primary goal of ARISE (Advanced Radio Interferometry between Space and Earth) is to use the technique of Space VLBI to increase our understanding of black holes and their environments, by imaging the havoc produced in the near vicinity of the black holes by their enormous gravitational fields. The mission will be based on a 25-meter space-borne radio telescope operating at frequencies between 8 and 86 GHz, roughly equivalent to an orbiting element of the Very Long Baseline Array. In an elliptical orbit with an apogee height of 40 000–100 000 km, ARISE will provide a resolution of 15 microarcsecond or better, 5–10 times better than that achievable on the ground. At frequencies of 43 and 86 GHz, the resolution of light weeks to light months in distant quasars will complement the gamma-ray and X-ray observations of high-energy photons, which come from the same regions near the massive black holes. At 22 GHz, ARISE will image the H2O maser disks in active galaxies more than 15 Mpc from Earth, probing accretion physics and giving accurate measurements of black-hole masses. ARISE also will study gravitational lenses at resolutions of tens of microarcseconds, yielding important information on the dark-matter distribution and on the possible existence of compact objects with masses of 10 3 M ⊙ to 10 6 M ⊙ .
MAGNIFICENT MAGNIFICATION: EXPLOITING THE OTHER HALF OF THE LENSING SIGNAL

We describe a new method for measuring galaxy magnification due to weak gravitational lensing. Our method makes use of a tight scaling relation between galaxy properties that are modified by gravitational lensing, such as apparent size, and other properties that are not, such as surface brightness. In particular, we use a version of the well-known fundamental plane relation for early-type galaxies. This modified photometric fundamental plane uses only photometric galaxy properties, eliminating the need for spectroscopic data. We present the first detection of magnification using this method by applying it to photometric catalogs from the Sloan Digital Sky Survey. This analysis shows that the derived magnification signal is within a factor of three of that available from conventional methods using gravitational shear. We suppress the dominant sources of systematic error and discuss modest improvements that may further enhance the lensing signal-to-noise available with this method. Moreover, some of the dominant sources of systematic error are substantially different from those of shear-based techniques. With this new technique, magnification becomes a useful measurement tool for the coming era of large ground-based surveys intending to measure gravitational lensing.
SYNTHESIS AND REDOX PROPERTIES OF TETRAETHYNYL TETRATHIAFULVALENES

Abstract The synthesis and characterization of protected tetraethynyltetrathiafulvalenes ( 1a and 1b ) is reported. The cation radical of 1a has a slightly more positive oxidation potential ( E ox0 1 = 0.63 V vs Ag AgCl ) than TTF. Stable CT solids can be prepared with iodine and TCNQF 4 . These compounds are the first members of a series of highly unsaturated TTF derivatives having in-plane π-orbitals.
The Impact of Wage Differentials on Choosing to Work in Agriculture

Based on a model of industry choice and wage determination, a 1% increase in the relative wage in agriculture increases the probability that a nonurban male with no more than a ninth-grade education works in agriculture by 3.37% at the sample mean and by 1.3% when averaged over the entire sample. A 10% increase in wages may increase the proportion of those males who choose to work in agriculture by nearly a quarter.
Designability and thermal stability of protein structures

Abstract Only about 1000 qualitatively different protein folds are believed to exist in nature. Here, we review theoretical studies which suggest that some folds are intrinsically more designable than others, i.e. are lowest energy states of an unusually large number of sequences. The sequences associated with these folds are also found to be unusually thermally stable. The connection between highly designable structures and highly stable sequences is generally known as the ‘designability principle’. The designability principle may help explain the small number of natural folds, and may also guide the design of new folds.
Relative income, race, and mortality.

Abstract This paper examines the relationship between relative income and mortality. Our research is motivated by recent literature that posits that, holding individual income fixed, those whose income are low relative to the incomes of those in a reference group will have worse health. We develop an empirical model in which an individual's health is a function of his or her own income and the incomes of those who live in the same geographical area. We show how this individual-level model can be estimated using semi-aggregated data on the mortality rates of people categorized by age, race, gender, and place of residence. The model is estimated using mortality data from the 1980 and 1990 Compressed Mortality Files, merged with income data from the 1980 and 1990 5% Public Use samples of the US Census. We find no evidence that having relatively wealthy neighbors, holding own income fixed, is associated with higher mortality. Instead, we find evidence that among some demographic and age groups—in particular working-aged black males—having relatively wealthy neighbors is associated with lower mortality. For example, among younger (aged 25–64) black men, an increase in the income of others is estimated to have a beneficial effect on mortality that is 40% as large as an equivalent increase in own income.
Infrared upconversion for astronomical applications

The performance of an upconversion system is examined for observation of astronomical sources in the low to middle infrared spectral range. Theoretical values for the performance parameters of an upconversion system for astronomical observations are evaluated in view of the conversion efficiencies, spectral resolution, field of view, minimum detectable source brightness and source flux. Experimental results of blackbody measurements and molecular absorption spectrum measurements using a lithium niobate upconverter with an argon-ion laser as the pump are presented. Estimates of the expected optimum sensitivity of an upconversion device which may be built with the presently available components are given.
Mobile ad hoc network proactive routing with delay prediction using neural network

Existing MANET routing protocols rely heavily on hop count evaluation. Although this is simple and efficient, it sacrifices the potential performance gains obtainable by considering other dynamic routing metrics. In this paper, we propose a delay prediction mechanism and its integration with a MANET proactive routing protocol. We demonstrate our approach of predicting mean queuing delay as a nonstationary time series using appropriate neural network models: Multi-Layer Perceptron or Radial Basis Function. To support MANET proactive routing, our delay prediction mechanism is devised as a distributed, independent, and continuous neural network training and prediction process conducted on individual nodes. We integrated our delay prediction mechanism with a well-known MANET proactive routing protocol--OLSR. The essential part of this integration is our TierUp algorithm, which is a novel node-state routing table computation algorithm. The structure and the key parameters of the resulting extended OLSR, called OLSR_NN, are also discussed. Our simulation shows that because of its capability of balancing the traffic, OLSR_NN is able to increase data packet delivery ratio and reduce average end-to-end delay in scenarios with complex traffic patterns and wide range of node mobility, compared to OLSR.
Collapse of Uniformly Rotating Stars to Black Holes and the Formation of Disks

Simulations in general relativity show that the outcome of collapse of a marginally unstable, uniformly rotating star spinning at the mass-shedding limit depends critically on the equation of state. For a very stiff equation of state, which is likely to characterize a neutron star, essentially all of the mass and angular momentum of the progenitor are swallowed by the Kerr black hole formed during the collapse, leaving nearly no residual gas to form a disk. For a soft equation of state with an adiabatic index Γ - 4/3 1, which characterizes a very massive or supermassive star supported predominantly by thermal radiation pressure, as much as 10% of the mass of the progenitor avoids capture and goes into a disk about the central hole. We present a semianalytic calculation that corroborates these numerical findings and shows how the final outcome of such a collapse may be determined from simple physical considerations. In particular, we employ a simple energy variational principle with an approximate, post-Newtonian energy functional to determine the structure of a uniformly rotating, polytropic star at the onset of collapse as a function of polytropic index n, where Γ = 1 + 1/n. We then use this data to calculate the mass and spin of the final black hole and ambient disk. We show that the fraction of the total mass that remains in the disk falls off sharply as 3 - n (equivalently, Γ - 4/3) increases.
Generalized parking functions, descent numbers, and chain polytopes of ribbon posets

We consider the inversion enumerator I"n(q), which counts labeled trees or, equivalently, parking functions. This polynomial has a natural extension to generalized parking functions. Substituting q=-1 into this generalized polynomial produces the number of permutations with a certain descent set. In the classical case, this result implies the formula I"n(-1)=E"n, the number of alternating permutations. We give a combinatorial proof of these formulas based on the involution principle. We also give a geometric interpretation of these identities in terms of volumes of generalized chain polytopes of ribbon posets. The volume of such a polytope is given by a sum over generalized parking functions, which is similar to an expression for the volume of the parking function polytope of Pitman and Stanley.
Influence of the dislocation density on the performance of heteroepitaxial indium phosphide solar cells

The authors point out that heteroepitaxial indium phosphide solar cells developed to date have low efficiency due to misfit dislocations. Dislocations act as recombination centers and strongly influence the solar cell performance. Calculations have been made to study the dependence of heteroepitaxial InP solar cell efficiency on dislocation density. The effects of surface recombination velocity and cell emitter thickness are also considered. Calculated results are compared with the available experimental results on representative InP solar cells. It is shown that heteroepitaxial InP cells with over 20% AM0 efficiency could be fabricated if dislocation density can be reduced to >
Metal cation:Glucopyranoside co-transport through a liquid organic membrane

Abstract A carrier admixture of phenylboronic acid and ionophore (cryptand or crown ether) simultaneously co-transports p-nitrophenyl β-glucopyranoside, M+ and OH−, through a liquid organic membrane. The transport mechanism involves the apparent self-assembly of a lipophilic ion-pair, comprising of anionic, phenylboronate-glucopyranoside adduct and metal cation-ionophore complex. Active glucopyranoside transport (i.e. uphill transport against a concentration gradient) was achieved in the direction of a metal cation concentration gradient.
Trigonal Bipyramidal M2Ch32- (M = Sn, Pb; Ch = S, Se, Te) and TlMTe33- Anions: Multinuclear Magnetic Resonance, Raman Spectroscopic, and Theoretical Studies, and the X-ray Crystal Structures of (2,2,2-crypt-K+)3TlPbTe33-·2en and (2,2,2-crypt-K+)2Pb2Ch32-·0.5en (Ch = S, Se)†

The series of group 14 metal trigonal bipyramidal anions has been extended to the mixed group 13/group 14 metal TlMTe33- anions (M = Sn, Pb), obtained by the reaction of Tl2M2Te3 and K2Te in en or in en/ethylamine mixtures and a stoichiometric excess of 2,2,2-crypt with respect to K+. The thallium anions were characterized in solution by 119Sn, 205Tl, 207Pb, and 125Te NMR spectroscopy. The small magnitudes of the relativistically corrected reduced coupling constants, 1(KM-Ch)RC and 1(KTl-Ch)RC, observed for the previously reported M2Ch32- (Ch = Se, Te) and the TlMTe33- anions are consistent with predominantly p-bonded cages, and this observation is supported by local and nonlocal density functional theory (DFT) calculations. Theory indicates M−M and Tl−M interactions of high s character corresponding to Mayer bond orders of 0.13−0.32. The (KM-M)RC and (KTl-M)RC couplings are unusually large compared to those of the butterfly-shaped Tl2Ch22- anions and likely arise from higher M−M and Tl−M bond orders, a l...
Segmentation under Occlusions Using Selective Shape Prior

In this work, we address the problem of segmenting multiple objects, under possible occlusions, in a level set framework. A variational energy that incorporates a piecewise constant representation of the image in terms of the object regions and the object spatial order is proposed. To resolve occluded boundaries, prior knowledge of the shape of objects is also introduced within the segmentation energy. By minimizing the above energy, we solve the segmentation with depth problem, i.e., estimating the object boundaries, the object intensities, and the spatial order. The segmentation with depth problem was originally dealt with by the Nitzberg-Mumford-Shiota (NMS) variational formulation, which proposes segmentation energies for each spatial order. We discuss the relationships and show the computational advantages of our formulation over the NMS model, mainly due to our treatment of spatial order estimation within a single energy. A novelty here is that the spatial order information available in the image model is used to dynamically impose prior shape constraints only to occluded boundaries. Also presented are experiments on synthetic and real images that have promising results.
Dynamic adjustments in channel width in response to a forced diversion: Gower Gulch, Death Valley National Park, California

We studied the 1941 diversion of Furnace Creek Wash (drainage area 439 km 2 ) into Gower Gulch (5.8 km 2 ) as an experiment in the transient response of a channel to a large change in water and sediment discharge. We measured sequential changes in valley width using a time series of aerial photographs (1948–1995), airborne laser elevation data from 2005, and a field survey. We found that the response of the system varied depending on the prediversion channel morphology and bedrock geology. In two steep knickzone segments, narrowing, knickpoint retreat and bedrock incision dominated, indicating a detachment-limited response. In the relatively low-gradient main part of Gower Gulch, widening dominated as the coarse postdiversion sediment load covered the channel bed. This transport-limited part of the system has undergone only modest incision and adjustments in gradient. Over long periods, the lowering rate of Gower Gulch probably depends on knickpoint retreat, but the present-day response of this non–steady-state system is a hybrid of incision and narrowing in detachment-limited reaches and widening in transport-limited reaches. This system demonstrates the importance of evolving channel geometry in setting the transient response of rivers to changes in forcing parameters.
Thiourea-catalyzed highly enantio- and diastereoselective additions of oxindoles to nitroolefins: application to the formal synthesis of (+)-physostigmine.

Oxindoles and their indoline derivatives are common structural motifs found in a wide array of natural and biologically active molecules. Most catalytic methods for the asymmetric syntheses of these compounds rely heavily on the use of transition-metal catalysts. In contrast, alternative catalytic procedures involving organocatalysis are scarce. Herein we disclose a conceptually novel organocatalytic approach to the syntheses of these materials using thiourea-catalyzed asymmetric 1,4-additions of oxindole derivatives to nitroolefins as a key step. These addition reactions create up to two stereogenic centers, one of which is a quaternary center. These reactions are broad in scope with respect to both the oxindole and nitroolefin substrates and provide the desired products in good yields with enantioselectivities of up to 99% and diastereoselectivities of up to >20:1. To demonstrate the utility of this approach, (+)-esermethole was synthesized in good overall yield over 3 steps starting from the 1,4-additi...