cssi/SciSciGPT-SciSciNet huggingface dataset:
Limitations of Lower-Bound Methods for the Wire Complexity of Boolean Operators

We study the circuit complexity of Boolean operators, i.e., collections of Boolean functions defined over a common input. Our focus is the well-studied model in which arbitrary Boolean functions are allowed as gates, and in which a circuit's complexity is measured by its depth and number of wires. We show sharp limitations of several existing lower-bound methods for this model. First, we study an information-theoretic lower-bound method due to Cherukhin, that yields bounds of form $\Omega_d(n \cdot \lambda_{d - 1}(n))$ on the number of wires needed to compute cyclic convolutions in depth $d \geq 2$. This was the first improvement over the lower bounds provided by the well-known super concentrator technique (for $d = 2, 3$ and for even $d \geq 4$). Cherukhin's method was formalized by Jukna as a general lower-bound criterion for Boolean operators, the ``Strong Multiscale Entropy'' (SME) property. It seemed plausible that this property could imply significantly better lower bounds by an improved analysis. However, we show that this is not the case, by exhibiting an explicit operator with the SME property that is computable in depth $d$ with $\cO(n \cdot \lambda_{d - 1}(n))$ wires, for $d = 2, 3$ and for even $d \geq 6$. Next, we show limitations of two simpler lower-bound criteria given by Jukna: the ``entropy method" for general operators, and the ``pair wise-distance method" for linear operators. We show that neither method gives super-linear lower bounds for depth $3$. In the process, we obtain the first known polynomial separation between the depth-2 and depth-3 wire complexities for an explicit operator. We also continue the study (initiated by Jukna) of the complexity of ``representing" a linear operator by bounded-depth circuits, a weaker notion than computing the operator.
Factorization and path integration of the Helmholtz equation: Numerical algorithms

The reduced scalar Helmholtz equation is addressed. The previously introduced factorization and path integration analysis is outlined. The resulting computational algorithm is briefly discussed and illustrated with several numerical examples appropriate for ocean seismo-acoustic modeling. Several extensions and further thematic developments are highlighted.
3D model of amphioxus steroid receptor complexed with estradiol.

The origins of signaling by vertebrate steroids are not fully understood. An important advance was the report that an estrogen-binding steroid receptor [SR] is present in amphioxus, a basal chordate with a similar body plan as vertebrates. To investigate the evolution of estrogen-binding to steroid receptors, we constructed a 3D model of amphioxus SR complexed with estradiol. This 3D model indicates that although the SR is activated by estradiol, some interactions between estradiol and human ERα are not conserved in the SR, which can explain the low affinity of estradiol for the SR. These differences between the SR and ERα in the steroid-binding domain are sufficient to suggest that another steroid is the physiological regulator of the SR. The 3D model predicts that mutation of Glu-346 to Gln will increase the affinity of testosterone for amphioxus SR and elucidate the evolution of steroid-binding to nuclear receptors.
The Evolution of Complex Life

In considering the probabilities that intelligent life might exist elsewhere in the Universe, it is important to ask questions about the factors governing the emergence of complex living organisms in the context of evolutionary biology, planetary environments and events in space. Two important problems arise. First, what can be learned about the general laws governing the evolution of complex life anywhere in space by studying its history on the Earth? Second, how is the evolution of complex life affected by events in space? To address these problems, a series of Science Workshops on the Evolution of Complex Life was held at the Ames Research Center. Included in this paper are highlights of those workshops, with particular emphasis on the first question, namely the evolution of complex extraterrestrial life.
The light variation and the orbital elements of am leonis = ADS 8024 A

The star was followed photoelectrically in two colors through five consecutive nights in 1968 at Kitt Peak National Observatory. The light of the fainter visual component (a physical companion) was excluded. At primary minimum the system undergoes a total eclipse lasting 25 min. New internally consistent elements have been derived. A subluminous region on the larger star can be located. The previous light curve by Abrami leads to the same geometrical elements but to different photometric elements even when freed from the light of the distant companion.
Structure–reactivity relationships in oxidation of C4 hydrocarbons on supported vanadia catalysts

Abstract Molecular vanadia species supported on the surface of metal oxides are used as catalysts for many hydrocarbon oxidation reactions. This paper discusses (i) the structure of the surface vanadia species in fresh and dehydrated catalysts, (ii) the structural and oxidation state changes during C4 hydrocarbon oxidation, and (iii) the roles of the oxide support, the surface oxygen species, and the acidity of the supported vanadia catalysts in selective oxidation catalysis. The molecular structure and reactivity information provides new fundamental insights into the catalytic properties of surface vanadia species during C4 hydrocarbon oxidation. On the other hand, the studies of the model supported vanadia catalysts shed new light on the origins of the catalytic activity of the bulk vanadium–phosphorus oxide (VPO) catalysts for partial oxidation of n -butane to maleic anhydride. The new fundamental structure–activity and selectivity relationships of surface vanadia species on oxide supports provide a foundation for the molecular engineering of supported catalysts for selective oxidation of hydrocarbons.
The phase diagram of four flavor SU(2) lattice gauge theory at nonzero chemical potential and temperature

Abstract SU(2) lattice gauge theory with four flavors of quarks is simulated at nonzero chemical potential μ and temperature T and the results are compared to the predictions of effective Lagrangians. Simulations on 164 lattices indicate that at zero T the theory experiences a second order phase transition to a diquark condensate state. Several methods of analysis, including equation of state fits suggested by Chiral Perturbation Theory, suggest that mean-field scaling describes this critical point. Nonzero T and μ are studied on 123×6 lattices. For low T, increasing μ takes the system through a line of second order phase transitions to a diquark condensed phase. Increasing T at high μ, the system passes through a line of first order transitions from the diquark phase to the quark–gluon plasma phase. Metastability is found near the first order line. Presumably, there is a tricritical point along this line of transitions. We estimate its position to be consistent with theoretical predictions.
Composite black holes in external fields

Abstract The properties of composite black holes in the background of electric or magnetic flux tubes are analyzed, both when the black holes remain in static equilibrium and when they accelerate under a net external force. To this effect, we present a number of exact solutions (generalizing the Melvin, C and Ernst solutions) describing these configurations in a theory that admits composite black holes with an arbitrary number of constituents. The compositeness property is argued to be independent of supersymmetry. Even if, in general, the shape of the horizon is distorted by the fields, the dependence of the extreme black hole area on the charges is shown to remain unchanged by either the external fields or the acceleration. We also discuss pair creation of composite black holes. In particular, we extend a previous analysis of pair creation of massless holes. Finally, we give the generalization of our solutions to include non-extreme black holes.
Numerical simulation of turbulence and sediment transport of medium sand

A model of sand transport in water is produced by combining a turbulence-resolving large eddy simulation (LES) with a discrete element model (DEM) prescribing the motion of individual grains of medium sand. The momentum effect of each particle on the fluid is calculated at the LES cell containing the particle, and the fluid velocity and pressure, interpolated to each particle center, is used to derive fluid force on each particle in the DEM. Eleven numerical experiments are conducted of an initially flat bed of particles. The experiments span a range of motion, from essentially no motion to vigorous suspension. Hydraulic roughness is found to increase abruptly at the transition from bed load to suspended load transport. Suspended sediment extracts momentum from the flow and decreases the rate of shear. Whereas, slightly higher in the flow, vertical drag by suspended grains damps turbulence and increases the rate of shear. Vertical sediment diffusivity and effective particle settling velocity are much smaller than is commonly assumed in suspended sediment models. The bed load experiments suggest that saltation by itself is a poor model of bed load sand transport. In contrast to expectations from saltation models, the peak bed load flux occurs at essentially the same level as the bed, and grains move slowly in frequent contact with other grains. Higher- and faster-moving bed load grains that can be considered to be in saltation represent a smaller portion of the total flux. Entrainment of bed load grains occurs in response to fluid penetration of the bed by high-vorticity turbulence structures embedded within broader high speed fluid regions referred to as a sweeps or high-speed wedges.
Surface and defect correlation studies on high resistivity 4H SiC bulk crystals and epitaxial layers for radiation detectors

Radiation detectors have been fabricated using bulk semi-insulating (SI) 4H-SiC crystals and SI and n-type 4H-SiC epitaxial layers grown by chemical vapor deposition (CVD) on highly doped (0001) 4H-SiC substrates. The devices have been characterized by optical microscopy, current-voltage (I-V) measurements, thermally stimulated current (TSC) spectroscopy (94K - 650 K), Hall effect, van der Pauw measurements, and electron beam induced current (EBIC) technique. Both epitaxial layers exhibited relatively shallow levels related to Al, B, L- and D- centers. Deep level centers in the n-type epitaxial layer peaked at ~ 400 K (E a ~ 1.1 eV) and ~ 470 K were correlated with IL2 defect and 1.1 eV center in high purity bulk SI 4H-SiC. The SI epitaxial layer exhibited peak at ~ 290 K (E a = 0.82 - 0.87 eV) that was attributed to IL1 center and 3C inclusions, and at ~ 525 K that was related to intrinsic defects and their complexes with energy levels close to the middle of the band gap. The TSC spectra of the SI epitaxial layer exhibited peaks with different current polarity which we attributed to the built-in electric field reversal. Results of EBIC and optical microscopy characterization showed segregation of threading dislocations around comet tail defects in the n-type epitaxial layers and presence of stacking faults and 3C-SiC inclusions in both epitaxial layers. The I-V characteristics of the devices on SI epi obtained in wide temperature range (94K - 650 K) exhibited steps at ~ 1 V and ~ 70 V corresponding to the ultimate trap filling of deep centers peaked at > 500 K and at ~ 250 K (E a ~ 0.57 eV), & ~ 300 K (E a ~ 0.85 eV) respectively. Slow processes of the injected carrier capture on traps resulted in the I-V characteristic with negative differential resistance (NDR). The high temperature resistivity measurements of bulk SI 4H-SiC sample revealed resistivity hysteresis that was attributed to the filling of the deep level electron trap centers.
Two-dimensional spectrophotometry of the cores of X-ray luminous clusters

The results of a two-dimensional spectrophotometric survey of the core regions of 11 rich clusters of galaxies are presented. A number of these clusters have spectacular optical emission line systems in their cores. Both morphologically and kinematically, the emission line regions divide into extended, 20-100 kpc systems of long linear filaments associated with the cluster core and more compact, homogeneous elongated regions associated with the dominant central cluster galaxy. It is suggested that the present results can be expected, as hot X-ray emitting gas cools in the cluster center. Luminosities almost entirely agree with expected values. The morphology of the systems can be understood if the filaments form initially in the cooling flow and, in some cases, are subsequently accreted by the central galaxy.
Meridional winds derived from COSMIC radio occultation measurements

[1] Meridional winds at the magnetic meridian in the upper thermosphere are derived from the peak height and density of the ionospheric F2 layer as retrieved by the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) satellites for 4 months from November 2006 to February 2007. These winds (referred to as COSMIC winds) are first validated by comparison at multiple locations with winds obtained from ground-based incoherent scatter radar (ISR) and Fabry-Perot interferometer (FPI) measurements. Then longitudinal variations of these winds are investigated and compared with simulations by the National Center for Atmospheric Research Thermosphere-Ionosphere-Electrodynamics General Circulation Model (NCAR TIE-GCM). The results show generally good agreement between COSMIC winds, ground-based measurements, and the simulations. Significant longitudinal variations are presented in the COSMIC winds. At 40°N (local winter), around midnight the COSMIC winds exhibit stronger and longer-duration equatorward velocities within 110°W–20°W (large negative magnetic declination sector) than those in other longitudes; during late morning hours the poleward winds show similar longitudinal variations. At 40°S (local summer), during the daytime the poleward winds are stronger within 120°E–110°W (large positive magnetic declination sector) than in 60°W–90°E (large negative magnetic declination sector), while during the nighttime the maximum equatorward winds shifts about 2 h later in 60°W–90°E than in 120°E–110°W. Analysis of the TIE-GCM simulations suggests that the longitudinal variation of meridional winds is mainly induced by magnetic declination due to the contribution of geographic zonal wind.
Gold-catalyzed 1,2-migration of silicon, tin, and germanium en route to C-2 substituted fused pyrrole-containing heterocycles.

An efficient method for the synthesis of fused pyrroloheterocycles from diverse propargyl-substituted heterocycles in the presence of Au-catalyst has been developed. The cascade transformation proceeds via alkyne−vinylidene isomerization with concomitant 1,2-shift of hydrogen, silyl, and stannyl groups. Remarkably, it was also shown that previously unknown 1,2-migration of a germyl group upon alkyne−vinylidene rearrangement occurs under these reaction conditions. This method allows for mild and efficient synthesis of diverse C-2 substituted N-containing heterocycles.
The Reflector Problem and the Inverse Square Law

We introduce a model to design reflectors that take into account the inverse square law for radiation. We prove existence of solutions in the near field case when the input and output energies are prescribed.
A generic framework for efficient and effective subsequence retrieval

This paper proposes a general framework for matching similar subsequences in both time series and string databases. The matching results are pairs of query subsequences and database subsequences. The framework finds all possible pairs of similar subsequences if the distance measure satisfies the "consistency" property, which is a property introduced in this paper. We show that most popular distance functions, such as the Euclidean distance, DTW, ERP, the Frechet distance for time series, and the Hamming distance and Levenshtein distance for strings, are all "consistent". We also propose a generic index structure for metric spaces named "reference net". The reference net occupies O(n) space, where n is the size of the dataset and is optimized to work well with our framework. The experiments demonstrate the ability of our method to improve retrieval performance when combined with diverse distance measures. The experiments also illustrate that the reference net scales well in terms of space overhead and query time.
Fluorescence intermittency and spectral shifts of single bio-conjugated nanocrystals studied by single molecule confocal fluorescence microscopy and spectroscopy

We have fabricated a combined measurement system capable of confocal microscopy and fluorescence spectroscopy to simultaneously evaluate multiple optical characteristics of single fluorescent nanocrystals. The single particle detection sensitivity is demonstrated by simultaneously measuring the dynamic excitation-time-dependent fluorescence intermittency and the emission spectrum of single cadmium selenide/zinc sulfide (CdSe/ZnS) nanocrystals (quantum dots, QDs). Using this system, we are currently investigating the optical characteristics of single QDs, the surface of which are conjugated with different ligands, such as trioctylphosphine oxide (TOPO), mercaptoundecanoicacid (MDA), and amine modified DNA (AMDNA). In this paper, we present the progress of our measurements of the time-dependent optical characteristics (fluorescence intermittency, photostability, and spectral diffusion) of single MDA-QDs and AMDNA-MDA-QDs in air in an effort to understand the effects of surface-conjugated biomolecules on the optical characteristics at single QD sensitivities.
Gate-level simulation of quantum circuits

Simulating quantum computation on a classical computer is a difficult problem. The matrices representing quantum gates, and vectors modeling qubit states grow exponentially with an increase in the number of qubits. However, by using a new data structure called the Quantum Information Decision Diagram (QuIDD) that exploits the structure of quantum operators, many of these matrices and vectors can be represented in a form that grows polynomially. Using QuIDDs, we implemented a general-purpose quantum computing simulator in C++ called QuIDDPro and tested it on Grover's algorithm. Our QuIDD technique asymptotically outperforms other known simulation techniques.
A rhodium a-frame complex: crystal structure of [Rh2(dppm)2(μ-OH)(CO)2][PF6]·(CH3)2CO

The crystal structure of [Rh 2 (dppm) 2 (/gm-OH)- (CO) 2 ] [PF 6 ]·(CH 3 ) 2 CO has been determined. The crystal and structure data are, M r = 1250.7, mono- clinic, P 2 1 / n , a = 10.165(3), b = 21.084(4), c = 25.85(1) A, β = 95.69(3)°, V = 5513(3) A 3 , Z = 4, D m (295 K) = 1.48, D x = 1.51 g cm −3 , Mo Kα, λ = 0.71069 A, μ = 5.03 cm −1 , F (000) = 2348, R = 0.0433, R w = 0.0462, 6257 observed reflections I >3/gs (I) . This molecule was found to be hydrogen- bonded to an acetone molecule in the lattice and has a Rh⋯Rh separation of 3.139(1) A, and a Rh(1) O(3)Rh(2) angle of 99.1(1)°. No other unusual structural features were observed.
Dynamical SUSY breaking in meta-stable vacua

Dynamical supersymmetry breaking in a long-lived meta-stable vacuum is a phenomenologically viable possibility. This relatively unexplored avenue leads to many new models of dynamical supersymmetry breaking. Here, we present a surprisingly simple class of models with meta-stable dynamical supersymmetry breaking: = 1 supersymmetric QCD, with massive flavors. Though these theories are strongly coupled, we definitively demonstrate the existence of meta-stable vacua by using the free-magnetic dual. Model building challenges, such as large flavor symmetries and the absence of an R-symmetry, are easily accommodated in these theories. Their simplicity also suggests that broken supersymmetry is generic in supersymmetric field theory and in the landscape of string vacua.
Free-space excitation of resonant cavities formed from cloaking metamaterial

We propose a new class of resonant electromagnetic structures, and study their response to free-space illumination. The structures consist of partial cylindrical shells that have the cloaking material properties proposed by Pendry et al. [Science 2006, 312, 1780]. These metamaterial shells have apertures that allow the propagation of incident irradiation into an interior resonant cavity. We use full wave time-harmonic analysis to study the field distribution inside the cavity, and show that an analogue of Whispering Gallery Modes (WGMs) can be efficiently excited via free-space illumination.
Parallel Experimentation: a basic scheme for dynamic efficiency

Evolutionary economics often focuses on the comparison between economic competition and the process of natural selection to select the fitter members of a given population. But that neglects the other “half” of an evolutionary process, the mechanism for the generation of new possibilities that is key to dynamic efficiency. My topic is the process of parallel experimentation which I take to be a process of multiple experiments running concurrently with some form of common goal, with some semi-isolation between the experiments, with benchmarking comparisons made between the experiments, and with the “migration” of discoveries between experiments wherever possible to ratchet up the performance of the group. The thesis is that parallel experimentation is a fundamental dynamic efficiency scheme to enhance and accelerate variation, innovation, and learning in contexts of genuine uncertainty or known ignorance. Within evolutionary biology, this type of parallel experimentation scheme was developed in Sewall Wright’s shifting balance theory of evolution. It addressed the rather neglected topic of how a population on a low fitness peak might eventually be able to go “downhill” against selective pressures, traverse a valley of low fitness, and then ascend a higher fitness peak. The theme of parallel experimentation is used to recast and pull together dynamic and pluralistic theories in economics, political theory, philosophy of science, and social learning.
Thresholds in Genotoxicity and Carcinogenicity : Urinary Bladder Carcinogenesis

Cancer is due to multiple alterations to DNA. Chemicals can increase the cancer risk by directly damaging DNA (DNA reactivity) or by increasing cell proliferation (DNA replications), increasing the number of opportunities for spontaneous DNA damage. Genotoxicity is a more comprehensive term than DNA reactivity. Many of the mechanisms of genotoxicity, such as clastogenicity, inhibition of DNA repair, or damage to the mitotic apparatus, produce DNA damage indirectly. These non-DNA reactive mechanisms involve interactions with proteins and mechanistically are threshold phenomena. 2-Acetylaminofluorene (AAF) is DNA reactive. Its dose response for urinary bladder DNA adduct formation is linear, whereas the tumor response is non-linear. Non-linearity is at the dose at which increased cell proliferation occurs, related to the threshold phenomenon of cytotoxicity. Non-linearity for DNA reactive carcinogens can also be produced by changes in metabolic processes of activation and/or deactivation due to saturable kinetics. Arsenic produces bladder cancer with a non-linear dose response in animal models and humans. Genotoxicity of arsenic occurs secondarily to indirect mechanisms, not DNA reactivity, it has a non-linear dose response, and the genotoxic mechanism appears to have a threshold, occurring only at doses in excess of toxic concentrations. Numerous non-genotoxic agents have been identified as bladder carcinogens in rodent models, most acting by inducing cytotoxicity with regenerative proliferation. Cytotoxicity can be produced by formation of urinary solids or by urinary reactive chemicals. Urinary solids are a defined threshold phenomenon based on the physical-chemical property of solubility. Likewise, chemical induction of cytotoxicity is a known threshold phenomenon. Non-genotoxic chemicals have a threshold dose response with respect to carcinogenesis, as do most genotoxic agents. DNA reactive chemicals have a non-linear dose response.
Heisenberg doubles and derived categories.

Let A be an abelian category of finite type and homological dimension 1. Then by results of Green R(A), the extended Hall-Ringel algebra of A, has a natural Hopf algebra structure. We consider its Heisenberg double Heis(A) and study its relation with D(A), the derived category of A. We show that Heis(A) can be viewed as a "Hall algebra" of D^{0,1}(A), the subcategory of complexes situated in degrees 0 and 1, in the following sense: if B is the heart of a t-structure on D(A) lying in D^{0,1}(A), then R(B) is naturally a subalgebra in Heis(A). Further, we define a new algebra L(A) called the lattice algebra of A, obtained by taking infinitely many copies of R(A), one for each site of an infinite 1-dimensional lattice and imposing Heisenberg double-type relations between copies at adjacent sites and oscillator-type relations between copies at non-adjacent sites. This algebra serves as the "Hall algebra" of the full derived category D(A) in the following sense: any derived equivalence D(A)-->D(B) induces an isomorphism of lattice algebras L(A)-->L(B).
Strong orthogonal decompositions and non‐linear impulse response functions for infinite‐variance processes

In this paper we prove Wold-type decompositions with strongorthogonal prediction innovations exist in smooth, re‡exive Banach spaces of discrete time processes if and only if the projection operator generating the innovations satis…es the property of iterations. Our theory includes as special cases all previous Wold-type decompositions of discrete time processes; completely characterizes when nonlinear heavy-tailed processes obtain a strong-orthogonal moving average representation; and easily promotes a theory of nonlinear impulse response functions for in…nite variance processes. We exemplify our theory by developing a nonlinear impulse response function for smooth transition threshold processes, we discuss how to test decomposition innovations for strong orthogonality and whether the proposed model represents the best predictor, and we apply the methodology to currency exchange rates.
Graphics Processing Units and High-Dimensional Optimization

This paper discusses the potential of graphics processing units (GPUs) in high-dimensional optimization problems. A single GPU card with hundreds of arithmetic cores can be inserted in a personal computer and dramatically accelerates many statistical algorithms. To exploit these devices fully, optimization algorithms should reduce to multiple parallel tasks, each accessing a limited amount of data. These criteria favor EM and MM algorithms that separate parameters and data. To a lesser extent block relaxation and coordinate descent and ascent also qualify. We demonstrate the utility of GPUs in nonnegative matrix factorization, PET image reconstruction, and multidimensional scaling. Speedups of 100 fold can easily be attained. Over the next decade, GPUs will fundamentally alter the landscape of computational statistics. It is time for more statisticians to get on-board.
Blowing of Lunar Soil by Apollo 12: Surveyor 3 Evidence

Analysis of discoloration patterns on the camera of the spacecraft Surveyor 3, after the Apollo 12 lunar module landed nearby, indicates that lunar surface particles were eroded and entrained by lunar modute exhaust during the landing and were ejected almost horizontally at 70 meters per second or faster. These particles struck the Surveyor camere and whitenzed its surface.
Hand2 elevates cardiomyocyte production during zebrafish heart development and regeneration

Embryonic heart formation requires the production of an appropriate number of cardiomyocytes; likewise, cardiac regeneration following injury relies upon the recovery of lost cardiomyocytes. The basic helix-loop-helix (bHLH) transcription factor Hand2 has been implicated in promoting cardiomyocyte formation. It is unclear, however, whether Hand2 plays an instructive or permissive role during this process. Here, we find that overexpression of hand2 in the early zebrafish embryo is able to enhance cardiomyocyte production, resulting in an enlarged heart with a striking increase in the size of the outflow tract. Our evidence indicates that these increases are dependent on the interactions of Hand2 in multimeric complexes and are independent of direct DNA binding by Hand2. Proliferation assays reveal that hand2 can impact cardiomyocyte production by promoting division of late-differentiating cardiac progenitors within the second heart field. Additionally, our data suggest that hand2 can influence cardiomyocyte production by altering the patterning of the anterior lateral plate mesoderm, potentially favoring formation of the first heart field at the expense of hematopoietic and vascular lineages. The potency of hand2 during embryonic cardiogenesis suggested that hand2 could also impact cardiac regeneration in adult zebrafish; indeed, we find that overexpression of hand2 can augment the regenerative proliferation of cardiomyocytes in response to injury. Together, our studies demonstrate that hand2 can drive cardiomyocyte production in multiple contexts and through multiple mechanisms. These results contribute to our understanding of the potential origins of congenital heart disease and inform future strategies in regenerative medicine.
Gold-catalyzed cycloisomerization of siloxy enynes to cyclohexadienes.

We have described the first Au-catalyzed cycloisomerization of 1-siloxy-5-en-1-ynes. The reaction is efficiently catalyzed by AuCl (1 mol %) to afford siloxy cyclohexadienes, which can be readily converted to the corresponding 1,2- and 1,3-cyclohexenones. The catalytic process displays a broad substrate scope and exceedingly mild reaction conditions (30 min, 20 °C). The presence of a siloxy alkyne moiety is crucial for enabling the skeletal reorganization process, which is postulated to proceed via a novel reaction mechanism involving a cascade of 1,2-alkyl migrations.
Is complex probability theory consistent with Bell's theorem?

Abstract Bayesian complex probability theory is shown to be consistent with Bell's theorem and with other recent limitations on local realistic theories which agree with the predictions of quantum mechanics.
Null polygonal Wilson loops and minimal surfaces in Anti-de-Sitter space

We consider minimal surfaces in three dimensional anti-de-Sitter space that end at the AdS boundary on a polygon given by a sequence of null segments. The problem can be reduced to a certain generalized Sinh-Gordon equation and to SU(2) Hitchin equations. We describe in detail the mathematical problem that needs to be solved. This problem is mathematically the same as the one studied by Gaiotto, Moore and Neitzke in the context of the moduli space of certain supersymmetric theories. Using their results we can find the explicit answer for the area of a surface that ends on an eight-sided polygon. Via the gauge/gravity duality this can also be interpreted as a certain eight-gluon scattering amplitude at strong coupling. In addition, we give fairly explicit solutions for regular polygons.
Blocking light in compact Riemannian manifolds

We study compact Riemannian manifolds (M, g) for which the light from any given point x e M can be shaded away from any other point y ∈ M by finitely many point shades in M. Compact flat Riemannian manifolds are known to have this finite blocking property. We conjecture that amongst compact Riemannian manifolds this finite blocking property characterizes the flat metrics. Using entropy considerations, we verify this conjecture amongst metrics with nonpositive sectional curvatures. Using the same approach, K Burns and E Gutkin have independently obtained this result. Additionally, we show that compact quotients of Euclidean buildings have the finite blocking property. On the positive curvature side, we conjecture that compact Riemannian manifolds with the same blocking properties as compact rank one symmetric spaces are necessarily isometric to a compact rank one symmetric space. We include some results providing evidence for this conjecture.
The future of single-authored papers

The fractions of single-authored papers in four science fields (astronomy, physics, chemistry, and biology) were determined at five-year intervals during 1975–2005. In each case the distribution is best fitted with an exponential function that never reaches zero, implying that single-authored papers will continue to be published in the foreseeable future. This is contrary to the prediction that they would become extinct.
Design of a multivariable helicopter flight control system for handling qualities enhancement

Abstract : New handling qualities specifications are currently being developed for attack helicopters. Most unaugmented helicopters will not meet these specifications and feedback control is necessary to improve handling qualities so that safe operation close to the earth in poor weather conditions and/or at night is possible. In this paper a methodology for the direct design of helicopter flight control systems which meet handling qualities specifications is presented. This methodology uses full state feedback to place closed loop eigenvalues to achieve bandwidth specifications and to shape closed loop eigenvectors to decouple lateral and longitudinal responses to control inputs. Full state feedback requires that all state variables be known; however, only angular rates and normal acceleration are measured by sensors. Thus, a state estimator is required in the feedback loop in order to convert sensor outputs to control inputs. This estimator is designed using eigenstructure assignment so as to achieve loop transfer recovery. Design of a feedback system for use in precise hovering control for a modern attack helicopter is used to illustrate the method. Control law synthesis is accomplished using an eighth order model which includes only rigid body modes. Control law performance is evaluated using a 37th order model which includes rigid body, actuator, rotor, sensor, and flexure dynamics. It is found that a notch filter must be added to the design in order to eliminate a high frequency instability. Once this is accomplished, both the time and frequency response characteristics of the augmented helicopter are much improved compared with the unaugmented helicopter.
Palladium-Catalyzed Coupling of Functionalized Primary and Secondary Amines with Aryl and Heteroaryl Halides: Two Ligands Suffice in Most Cases

We report our studies on the use of two catalyst systems, based on the ligands BrettPhos and RuPhos, which provide the widest scope for Pd-catalyzed C–N cross-coupling reactions to date. Often low catalyst loadings and short reaction times can be used with functionalized aryl and heteroaryl coupling partners. The reactions are highly robust and can be set up and performed without the use of a glovebox. These catalysts should find wide application in the synthesis of complex molecules including pharmaceuticals, natural products and functional materials.
Synthetic studies directed toward the liposidomycins: Preparation and reactions of serine-derived epoxides

Summary The preparation of an oxiranyl serine derivative which will be incorporated into the diazepanone fragment of the liposidomycin B core subunit is described. Reactions of the epoxide with nitrogen nucleophiles afforded the 1,2-(O,N-protected)-4-N-functionalized-3-butanols in modest to good yields. A Mosher ester analysis of the alcohol resulting from azide promoted oxirane ring opening is also discussed.
On the classification of ideal secret sharing schemes

In a secret sharing scheme a dealer has a secret key. There is a finite set P of participants and a set ? of subsets of P. A secret sharing scheme with ? as the access structure is a method which the dealer can use to distribute shares to each participant so that a subset of participants can determine the key if and only if that subset is in ?. The share of a participant is the information sent by the dealer in private to the participant. A secret sharing scheme is ideal if any subset of participants who can use their shares to determine any information about the key can in fact actually determine the key, and if the set of possible shares is the same as the set of possible keys. In this paper we show a relationship between ideal secret sharing schemes and matroids.
Depression, suicidal ideation, and suicidal attempt presenting to the emergency department: differences between these cohorts

Introduction: The World Health Organization estimates that one million people die by suicide every year. Few studies have looked at factors associated with disposition in patients with chief complaints of depression, suicidal ideation (SI) and suicidal attempts (SA) who present to the emergency department (ED). Our objective was to assess individual determinants associated with ED disposition of patients in depressed patients presenting to the ED. Methods: We conducted a retrospective study using the National Hospital Ambulatory Medical Care Survey from 2006 to 2008. We used logistic regression to identify factors associated with discharge, in SI, SA and depression patients. Independent variables included socio-demographic information, vital signs, mode of arrival, insurance status, place of residence and concomitant psychiatric diagnosis. Results: Of the 93,030 subjects, 2,314 met the inclusion criteria (1,362 depression, 353 SI and 599 SA). Patients who arrived by ambulance were less likely to be discharged (odds ratio [OR] 0.63, 95% confidence interval [CI] 0.43-0.92). Hispanic patients and patients age 15 to 29 were likely to be discharged (OR 1.61, 95% CI 1.16-2.24 and OR 1.55, 95% CI 1.15-2.10 respectively). Insurance status and housing status were not significantly associated patient was being discharge from EDs. Conclusion: The Hispanic population had higher discharge rates, but the reasons are yet to be explored. Patients with SA and SI are discharged less frequently than those with depression, regardless of insurance type or housing status. [West J Emerg Med. 2014;15(2):211–216.]
Real-Time Virtual Channel Flow Control

Real-time communication system support for large scale parallel multicomputers becomes an important issue as the number of real-time applications developed on these systems increases. Flow control is a key component that affects the performance of the communication subsystem. We develop a range of new real-time virtual channel flow control schemes for wormhole networks. The flow control schemes differ in their priority mapping strategies, priority adjustment methods, and arbitration functions. The priority mapping strategy and priority adjustment method of a flow control scheme determine the priority of a message. The priority of a message is used for the virtual channel assignment and the physical channel arbitration. We discuss the trade-off between the performance and the hardware cost of each flow control scheme. A simulator is implemented for studying the performance of the schemes, and simulation experiments are designed to compare the importance of priority mapping, priority adjustment and arbitration toward the system performance. As wormhole networks scale to larger sizes, the average distance between source and destination nodes increases. The flits of messages in wormhole networks, which are buffered in nodes along the path from the source to the destination, consume network resources in these nodes. Therefore, increased scaling may lead to increased resource consumption, congestion, and late messages. In real-time systems, messages lose their value when they miss their deadlines. In order to reduce congestion, we provide a scheme for dropping messages that miss their deadlines.
Radio-Selected Quasars in the Sloan Digital Sky Survey

We have conducted a pilot survey for z > 3.5 quasars by combining the FIRST radio survey with the Sloan Digital Sky Survey (SDSS). While SDSS already targets FIRST sources for spectroscopy as quasar candidates, our survey includes fainter quasars and greatly improves the discovery rate by using strict astrometric criteria for matching the radio and optical positions. Our method allows for selection of high-redshift quasars with less color bias than with optical selection, as using radio selection essentially eliminates stellar contamination. We report the results of spectroscopy for 45 candidates, including 29 quasars in the range 0.37 3.5. We compare quasars selected using radio and optical criteria, and find that radio-selected quasars have a much higher fraction of moderately reddened objects. We derive a radio-loud quasar luminosity function at 3.5 < z < 4.0, and find that it is in good agreement with expectations from prior SDSS results.
Dry catalytic liquefaction of a subbituminous coal: structural inferences☆

Abstract The catalytic liquefaction of a subbituminous coal has been studied in the absence of solvent using an impregnated sulphided Mo catalyst. Reactions were conducted for various times at temperatures in the range 300–400 °C. The yield and composition of gaseous and chloroform-soluble products and insoluble residue were followed as a function of the reaction conditions, using a number of techniques. The activity of the catalyst in promoting the production of liquids is dependent upon temperature. The main function of the catalyst may be to dissociate molecular hydrogen rather than directly participate in bond-cleavage reactions. At 300 °C, the catalyst had little effect on liquids production although it appears to cause some reduction in cross-link density due to the cleavage and stabilization of weaker bonds. At higher temperatures, the presence of the catalyst is necessary to obtain high liquid yields. The liquids first produced (up to ≈ 10%) are highly aliphatic and appear to be held within the coal structure by weak bonding or physical entrapment. At higher yields, the liquids are more aromatic and derive substantially from the breakdown of the coal network structure. Sharp changes in composition on going from low to high yield provide a basis for estimating the mobile phase content of the coal (10–20%). Associated changes in the structure and composition of the chloroform-insoluble residue have been further investigated by petrographic analysis and by measurements of swelling in pyridine. The high-swelling ratios measured for the parent coal and for the residues at low liquid conversions ( 20%) are consistent with the elimination of functional groups and an increase in cross-link density caused by condensation reactions.
Stationary and static stellar dynamic models with axial symmetry

We study the existence of stationary solutions of the Vlasov-Poisson system with finite radius and finite mass in the stellar dynamics case. So far, the existence of such solutions is known only under the assumption of spherical symmetry. Using the implicit function theorem we show that certain stationary, spherically symmetric solutions can be embedded in one parameter families of stationary, axially symmetric solutions with finite radius and finite mass. In general, these new steady states have non-vanishing average velocity field, but they can also be constructed such that their velocity field does vanish, in which case they are called static.
Discontinuous Galerkin finite element method applied to the 1-D spherical neutron transport equation

Discontinuous Galerkin finite element methods are used to estimate solutions to the non-scattering 1-D spherical neutron transport equation. Various trial and test spaces are compared in the context of a few sample problems whose exact solution is known. Certain trial spaces avoid unphysical behaviors that seem to plague other methods. Comparisons with diamond differencing and simple corner-balancing are presented to highlight these improvements.
The Metal Content of Dwarf Starburst Winds: Results from Chandra Observations of NGC 1569*

We present deep Chandra spectral imaging of the dwarf starburst galaxy NGC 1569. The unprecedented spatial resolution allows us to spatially identify the components of the integrated X-ray spectrum. Fitted spectral models require an intrinsic absorption component and higher metal abundances than previous studies indicated. Our results provide the first direct evidence for metal-enriched winds from dwarf starburst galaxies. We identify 14 X-ray point sources in NGC 1569. Most have properties consistent with those of high-mass X-ray binaries, but one is a steep-spectrum radio source that is probably a supernova remnant. The X-ray luminosity of NGC 1569 is dominated by diffuse, thermal emission from the disk (0.7 keV) and bipolar halo (0.3 keV). Photoelectric absorption from the inclined H I disk hardens the X-ray spectrum on the northern side of the disk relative to the southern side. Requiring the fitted absorption column to match the H I column measured at 21 cm implies that the metallicity of the H I disk is significantly less than solar but greater than 0.1 Z☉. Hence, much of the H I is enriched to levels comparable to the metallicity of the H II regions [O/H = 0.2(O/H)☉]. The X-ray color variations in the halo are inconsistent with a free-streaming wind and probably reveal the location of shocks created by the interaction of the wind with a gaseous halo. The X-ray spectrum of the diffuse gas presents strong emission lines from α-process elements. Fitted models require α-element abundances greater than 0.25 Zα, ☉ and ratios of α-elements to iron 2-4 times higher than the solar ratio. The best fit to the spectrum is obtained with solar mass fractions for the α-elements, 1.0 Zα, ☉, but a degeneracy between the metallicity and the spectral normalization prevents us from deriving an upper limit on the wind metallicity from the X-ray spectrum alone. We argue, however, that abundances larger than 2.0 Zα, ☉ pose awkward implications for the dynamical evolution of the wind based on our knowledge of the starburst properties. For consistency with our best-fitting abundances, the mass of interstellar gas entrained in the wind must be about 9 times the mass of stellar ejecta in the wind. Most of the oxygen carried by the wind comes from the stellar ejecta rather than entrained interstellar gas. The estimated mass of oxygen in the hot wind, 34,000 M☉, is similar to the oxygen yield of the current starburst. Apparently the wind carries nearly all the metals ejected by the starburst. These metals appear destined to contribute to the enrichment of the intergalactic medium. Much of the nucleosynthesis in NGC 1569 must have occurred during less violent periods of star formation, however, because our measurements imply that the neutral gas disk holds at least 5 times more oxygen than wind.
Turbulent Boundary Layers Over Surfaces Smoothed by Sanding

Abstract : Flat-plate turbulent boundary layer measurements have been made on painted surfaces, smoothed by sanding. The measurements were conducted in a closed return water tunnel, over a momentum thickness Reynolds number (Re(theta)) range of 3000 to 16,000, using a two-component laser Doppler velocimeter (LDV). The mean velocity and Reynolds stress profiles are compared with those for smooth and sandgrain rough walls. The results indicate an increase in the boundary layer thickness (d) and the integral length scales for the unsanded, painted surface compared to a smooth wall. More significant increases in these parameters, as well as the skin-friction coefficient (C(f)) were observed for the sandgrain surfaces. The sanded surfaces behave similarly to the smooth wall for these boundary layer parameters. The roughness functions (DeltaU(+)) for the sanded surfaces measured in this study agree within their uncertainty with previous results obtained using towing tank tests and similarity law analysis. The present results indicate that the mean profiles for all of the surfaces collapse well in velocity defect form. The Reynolds stresses also show good collapse in the overlap and outer regions of the boundary layer when normalized with the wall shear stress.