cssi/SciSciGPT-SciSciNet huggingface dataset:
Nambu quantum mechanics: A Nonlinear generalization of geometric quantum mechanics

We propose a generalization of the standard geometric formulation of quantum mechanics, based on the classical Nambu dynamics of free Euler tops. This extended quantum mechanics has in lieu of the standard exponential time evolution, a nonlinear temporal evolution given by Jacobi elliptic functions. In the limit where latter's moduli parameters are set to zero, the usual geometric formulation of quantum mechanics, based on the Kahler structure of a complex projective Hilbert space, is recovered. We point out various novel features of this extended quantum mechanics, including its geometric aspects. Our approach sheds a new light on the problem of quantization of Nambu dynamics. Finally, we argue that the structure of this nonlinear quantum mechanics is natural from the point of view of string theory.
Dynamic Tolling Strategies for Managed Lanes

This paper proposes two sensible approaches that may be potentially implemented in practice to determine pricing strategies for operating managed toll lanes. The tolls vary dynamically in response to real-time traffic conditions in order to provide a superior free-flow travel service to the users of the toll lanes while maximizing the freeway’s throughput. Simulation experiments are conducted to validate and compare the proposed approaches.
Energies of Cosmic-Ray Particles

Cloud chamber photographs of cosmic-ray tracks in a magnetic field up to 17,000 gauss are shown. On the assumption that the particles producing the tracks are traveling downward through the chamber rather than upward, particles of positive charge appear as well as electrons. From the specific ionization along the track it is concluded that the positives are protons, and are not nuclei of charge greater than unity. No evidence is uncovered demanding the introduction of a neutron for cosmic-ray phenomena. Eight examples of associated tracks are shown. Energies range from below 10 6 electron-volts to values in a few cases of the order of 10 9 electron-volts. Energy values for 70 tracks are listed. The scattering of cosmic particles in traversing a 6.0 mm lead plate is measured.
The autoradioluminescence of uranyl salts. A new luminescence emission standard for 500 – 600 nm

Abstract The autoradioluminescence (ARL) from uranyl ion (less than 0.2 M) arises exclusively via β emission from 238U daughters 234Th and 234Pa). Dilute aqueous solutions of uranyl nitrate freed from these daughters show no spontaneous light emission, but the steady state luminescence is exponentially re-established with the 24 day half-life of 234Th as originally described in the classic work of Rutherford and Soddy. However, concentrated solutions and solid uranyl nitrate also luminesce from α stimulation. The spectral distribution of the ARL from uranyl nitrate at λ > 400 nm in aqueous solution is identical to that of UO22+ fluorescence. The ARL of “aged” uranyl nitrate is linear in concentration (less than 0.2 M) in a number of solvents, and is invariant from preparations stored for several months. These solutions are useful for calibration of instruments where very low light levels are involved.
Dynamic scaling phenomena in growth processes

Abstract Inhomogeneities in a deposition process may lead to formation of rough surfaces. Fluctuations in the height h(x, t), of the surface (at location x and time t) can be probed directly by scanning microscopy, or indirectly by scattering. Analytical or numerical treatments of simple growth models suggest that, quite generally, the height fluctuations have a self-similar character, their average correlations exhibiting a dynamic scaling form, 〈[h(x, t) − h(x′, t′)]2〉 = |x − x′|2α ƒ(|x − x′|z/|t − t′|). The roughness and dynamic exponents, α and z, are expected to be universal, depending only on the underlying mechanism that generates self-similar scaling. Despite its ubiquitous occurrence in theory and simulations, experimental confirmation of dynamic scaling has been scarce. In some cases where such scaling has been observed, the exponents are different from those expected on the basis of analysis or numerics. I shall briefly review the theoretical foundations of dynamic scaling, and suggest possible reasons for discrepancies with experimental results.
HYPERBOLIC GROUPS ADMIT PROPER AFFINE ISOMETRIC ACTIONS ON l p -SPACES

In this paper, we show that hyperbolic groups admit proper affine isometric actions on $l^p$-spaces.
Investigation of long term storage effects on aerospace nickel-cadmium cell performance

A study on evaluation of the long term storage effects on aerospace nickel-cadmium cells currently being performed at NASA/Goddard Space Flight Center (GSFC) is described. A number of cells of 6 Ah and 12 Ah capacities which were stored in shorted condition for 8 to 9 years at the GSFC were selected for this study. These cells will undergo electrical acceptance testing the the GSFC, and life cycling at the NASA Battery Test Facility at the Naval Weapons Facility at the Naval Weapons Support Center (NWSC) in Crane, Indiana; in addition, some cells from the study will undergo destructive analyses.
3-D and Quasi-2-D Discrete Element Modeling of Grain Commingling in a Bucket Elevator Boot System

Unwanted grain commingling impedes new quality-based grain handling systems and has proven to be an expensive and time-consuming issue to study experimentally. Experimentally validated models may reduce the time and expense of studying grain commingling while providing additional insight into details of the particle flow. In this study, grain commingling in a pilot-scale bucket elevator boot was first modeled in three-dimensional (3-D) discrete element method (DEM) simulations. Experiments on the pilot-scale boot were performed using red-dyed and clear (uncolored) soybeans to validate the 3-D DEM model. Predicted results from the 3-D boot model generally followed the experimental data but tended to underpredict commingling early in the process. To reduce computational time, quasi-two-dimensional (quasi-2-D) DEM simulations were also evaluated. Comparison of predicted average commingling of five quasi-2-D boot models with reduced control volumes (i.e., with boot widths from four to seven times the mean particle diameter) led to the selection of the quasi-2-D model with a boot width of 5.6 times the mean particle diameter (i.e., 5.6d) to reduce computational time. In addition, the 3-D and quasi-2-D (5.6d) models were refined by accounting for the initial surge of particles at the beginning of each test and correcting for the effective dynamic gap between the bucket cups and the boot wall. The quasi-2-D (5.6d) models reduced simulation run time by approximately 70% compared to the 3-D model of the pilot-scale boot. Results of this study can be used to accurately predict commingling levels and improve grain handling, which can help farmers and grain handlers reduce costs and maintain grain purity during transport and export of grain.
A weak equivalence principle test on a suborbital rocket

We describe a Galilean test of the weak equivalence principle, to be conducted during the free fall portion of a sounding rocket flight. The test of a single pair of substances is aimed at a measurement uncertainty of ?(?) < 10?16 after averaging the results of eight separate drops. The weak equivalence principle measurement is made with a set of four laser gauges that are expected to achieve 0.1 pm Hz?1/2. The discovery of a violation (? ? 0) would have profound implications for physics, astrophysics and cosmology.
The synthesis of nitrocyclopropanes from nitrodiazomethanes

Abstract The synthesis of novel 1-substituted nitrocyclopropanes using the rhodium(II) acetate catalyzed cyclopropanation reaction of several nitrodiazomethanes with electron rich alkenes is described.
A novel synthesis of compounds containing a fused pyrrole ring from cyclic ketones and N-BOC-L-phenylalaninal

Abstract A synthesis of fused pyrrole-containing compounds from N-Boc-L-phenylalaninal and cyclic ketones is described.
On the Indirect Detection of Sodium in the Atmosphere of the Planetary Companion to HD 209458

Using a self-consistent atmosphere code, we construct a new model of the atmosphere of the transiting extrasolar giant planet HD 209458b to investigate the disparity between the observed strength of the sodium absorption feature at 589 nm and the predictions of previous models. For the atmospheric temperature-pressure profile we derive, silicate and iron clouds reside at a pressure of several millibars in the planet's atmosphere. These clouds have significant vertical extent and optical depth because of our slant viewing geometry and lead to increased absorption in bands directly adjacent to the sodium line core. Using a non-LTE sodium ionization model that includes photoionization by stellar UV flux, collisional processes with H2, and radiative recombination, we show that the ionization depth in the planet's atmosphere reaches ~ mbar at the day/night terminator. Ionization leads to a slight weakening of the sodium feature. We present our baseline model, including ionization and clouds, which falls near the observational error bars. The sensitivity of our conclusions to the derived atmospheric temperature-pressure profile is discussed.
A techno-economic analysis and optimization of Li-ion batteries for light-duty passenger vehicle electrification

Abstract We conduct a techno-economic analysis of Li-ion NMC-G prismatic pouch battery and pack designs for electric vehicle applications. We develop models of power capability and manufacturing operations to identify the minimum cost cell and pack designs for a variety of plug-in hybrid electric vehicle (PHEV) and battery electric vehicle (BEV) requirements. We find that economies of scale in battery manufacturing are reached quickly at a production volume of ∼200–300 MWh annually. Increased volume does little to reduce unit costs, except potentially indirectly through factors such as experience, learning, and innovation. We also find that vehicle applications with larger energy requirements are able to utilize cheaper cells due in part to the use of thicker electrodes. The effect on cost can be substantial. In our base case, we estimate pack-level battery production costs of ∼$545 kWh−1 for a PHEV with a 10 mile (16 km) all-electric range (PHEV10) and ∼$230 kWh−1 for a BEV with a 200 mile (320 km) all-electric range (BEV200). This 58% reduction, from $545 kWh−1 to $230 kWh−1, is a larger effect than the uncertainty represented by our optimistic and pessimistic scenarios. Electrodes thicker than about 100 or 125 microns are not currently used in practice due to manufacturing and durability concerns, but relaxing this constraint could further lower the cost of larger capacity BEV200 packs by up to an additional 8%.
Gaussian free fields for mathematicians

The d-dimensional Gaussian free field (GFF), also called the (Euclidean bosonic) massless free field, is a d-dimensional-time analog of Brownian motion. Just as Brownian motion is the limit of the simple random walk (when time and space are appropriately scaled), the GFF is the limit of many incrementally varying random functions on d-dimensional grids. We present an overview of the GFF and some of the properties that are useful in light of recent connections between the GFF and the Schramm–Loewner evolution.
A Geometric Approach to Acyclic Orientations

The set of acyclic orientations of a connected graph with a given sink has a natural poset structure. We give a geometric proof of a result of Jim Propp: this poset is the disjoint union of distributive lattices.
Gold‐Catalyzed Dehydrative Transformations of Unsaturated Alcohols

The activation of allylic and propargylic alcohols for use as electrophiles represents a burgeoning new area in homogeneous gold catalysis. This review covers Au-catalyzed substitution reactions of unsaturated alcohols in which water serves as leaving group. Attention is given to different substrate classes and the mechanisms by which the reactions are believed to occur. Recent advances in chirality transfer and enantioselective reactions are also reviewed.
Gauge theories from D7-branes over vanishing 4-cycles.

We study quiver gauge theories on D7-branes wrapped over vanishing holomorphic 4-cycles. We investigate how to incorporate O7-planes and/or flavor D7-branes, which are necessary to cancel anomalies. These theories are chiral, preserve four supercharges and exhibit very rich infrared dynamics. Geometric transitions and duality in the presence of O-planes are analyzed. We study the Higgs branch of these quiver theories, showing the emergence of fuzzy internal dimensions. This branch is related to noncommutative instantons on the divisor wrapped by the seven-branes. Our results have a natural application to the recently introduced F(uzz) limit of F-theory.
E. O. Wilson as Moralist

E. O. Wilson offers descriptive and normative analyses of morality. Regarding science as the only proper basis for explaining and developing morality, he has not sufficiently accounted for the complexity of human conduct in this arena. Wilson's account of evolved proclivities, however, indicates important features of human nature that moral theorists ignore at their peril.
Development of an agent-based distribution test feeder with smart-grid functionality

This paper reports on the development of an agent-based distribution test feeder with smart-grid functionality. The test feeder is based on an actual distribution feeder with various additional features incorporated, including rooftop photovoltaic generation and price-responsive loads (e.g., plug-in electric vehicles and intelligent air-conditioning systems). This work aims to enable the integrated study of wholesale electric power markets coupled with detailed representations of the retail-side distribution systems.
Kleinian groups with discrete length spectrum

We characterize finitely generated torsion-free Kleinian groups for which the real length spectrum (without multiplicities) is discrete.
Neutrino helicity reversal and fundamental symmetries

A rather elusive helicity reversal occurs in a gedanken experiment in which a massive left-handed Dirac neutrino, traveling at a velocity u < c, is overtaken on a highway by a speeding vehicle (traveling at velocity v with u < v < c). Namely, after passing the neutrino, looking back, one would see a right-handed neutrino (which has never been observed in nature). The Lorentz-invariant mass of the right-handed neutrino is still the same as before the passing. The gedanken experiment thus implies the existence of right-handed, light neutrinos, which are not completely sterile. Furthermore, overtaking a bunch of massive right-handed Dirac neutrinos leads to gradual de-sterilization. We discuss the helicity reversal and the concomitant sterilization and de-sterilization mechanisms by way of an illustrative example calculation, with a special emphasis on massive Dirac and Majorana neutrinos. We contrast the formalism with a modified Dirac neutrino described by a Dirac equation with a pseudoscalar mass term proportional to the fifth current.
FITTING PHOTOMETRY OF BLENDED MICROLENSING EVENTS

We reexamine the usefulness of fitting blended light-curve models to microlensing photometric data. We find agreement with previous workers (e.g., Wozniak & Paczynski) that this is a difficult proposition because of the degeneracy of blend fraction with other fit parameters. We show that follow-up observations at specific point along the light curve (peak region and wings) of high-magnification events are the most helpful in removing degener- acies. We also show that very small errors in the baseline magnitude can result in problems in measuring the blend fraction and study the importance of non-Gaussian errors in the fit results. The biases and skewness in the dis- tribution of the recovered blend fraction is discussed. We also find a new approximation formula relating the blend fraction and the unblended fit parameters to the underlying event duration needed to estimate microlensing optical depth. Subject headings: gravitational lensing — methods: data analysis
Surface patches from unorganized space curves

Recent 3D sketch tools produce networks of three-space curves that suggest the contours of shapes. The shapes may be non-manifold, closed three-dimensional, open two-dimensional, or mixed. Our video demonstrates a system that automatically generates intuitively appealing, piecewise-smooth surface patches from such a curve network, and an intelligent user interface for modifying the automatically chosen surface patches. Both parts of the system use a linear algebra representation of the set of surface patches to track the topology.
Applications of Riemann‐Hilbert problem techniques to electromagnetic coupling through apertures

The generalized dual series approach, as it is applied to the mixed boundary value problems that characterize the coupling of electromagnetic energy through apertures, is described. This approach is based upon techniques borrowed from the analysis of the Riemann-Hilbert problem of complex variable theory. It allows one to obtain essentially analytical solutions to families of canonical coupling problems in separable geometries. The generalized dual series approach is illustrated with the example of the coupling of an H-polarized plane wave to a perfectly conducting infinite cylinder with an infinite axial slot enclosing a concentric impedance cylinder. This problem encompasses the coupling to an empty cylinder as well as to a cylinder enclosing a conducting wire or cable. The solution explicitly exhibits the correct behavior near the edge of the aperture, and it can handle small to large ratios of cylinder radius to wavelength without additional special considerations. The angle of incidence is arbitrary. Results are shown for a normal incidence case and for a case in which the direction of incidence coincides with the edge of the aperture. A brief comparison with related moment method results is given.
Genomically encoded analog memory with precise in vivo DNA writing in living cell populations

Cellular memory is crucial to many natural biological processes and sophisticated synthetic biology applications. Existing cellular memories rely on epigenetic switches or recombinases, which are limited in scalability and recording capacity. In this work, we use the DNA of living cell populations as genomic "tape recorders" for the analog and distributed recording of long-term event histories. We describe a platform for generating single-stranded DNA (ssDNA) in vivo in response to arbitrary transcriptional signals. When coexpressed with a recombinase, these intracellularly expressed ssDNAs target specific genomic DNA addresses, resulting in precise mutations that accumulate in cell populations as a function of the magnitude and duration of the inputs. This platform could enable long-term cellular recorders for environmental and biomedical applications, biological state machines, and enhanced genome engineering strategies.
Protocols for Asymmetric Communication Channels

In this paper we examine the problem of sending an n-bit data item from a client to a server across an asymmetric communication channel. We demonstrate that there are scenarios in which a high-speed link from the server to the client can be used to greatly reduce the number of bits sent from the client to the server across a slower link. In particular, we assume that the data item is drawn from a probability distribution D that is known to the server but not to the client. We present several protocols in which the expected number of bits transmitted by the server and client are O(n) and O(H(D)+1), respectively, where H(D) is the binary entropy of D (and can range from 0 to n). These protocols are within a small constant factor of optimal in terms of the number of bits sent by the client. The expected number of rounds of communication between the server and client in the simplest of our protocols is O(H(D)). We also give a protocol for which the expected number of rounds is only O(1), but which requires more computational effort on the part of the server. A third technique provides a tradeoff between the computational effort and the number of rounds. These protocols are complemented by several lower bounds and impossibility results. We prove that all of our protocols are existentially optimal in terms of the number of bits sent by the server, i.e., there are distributions for which the total number of bits exchanged has to be at least n. In addition, we show that there is no protocol that is optimal for every distribution (as opposed to just existentially optimal) in terms of bits sent by the server. We demonstrate this by proving that it is undecidable to compute (even approximately), for an arbitrary distribution D, the expected number of bits that must be exchanged by the server and client on the distribution D.
Constraining dark matter halo profiles and galaxy formation models using spiral arm morphology. II. dark and stellar mass concentrations for 13 nearby face-on galaxies

We investigate the use of spiral arm pitch angles as a probe of disk galaxy mass profiles. We confirm our previous result that spiral arm pitch angles (P) are well correlated with the rate of shear (S) in disk galaxy rotation curves. We use this correlation to argue that imaging data alone can provide a powerful probe of galactic mass distributions out to large look-back times. We then use a sample of 13 galaxies, with Spitzer 3.6 ?m imaging data and observed H? rotation curves, to demonstrate how an inferred shear rate coupled with a bulge-disk decomposition model and a Tully-Fisher-derived velocity normalization can be used to place constraints on a galaxy's baryon fraction and dark matter halo profile. Finally, we show that there appears to be a trend (albeit a weak correlation) between spiral arm pitch angle and halo concentration. We discuss implications for the suggested link between supermassive black hole (SMBH) mass and dark halo concentration, using pitch angle as a proxy for SMBH mass.
Optimal Coherence Using Chirped Pulse Trains for Enhanced Imaging

We propose adiabatic passage control scheme to maximize coherence in selected vibrational mode. We demonstrate possibility for sustaining high coherence in the presence of dephasing by two chirped pulse trains. Method may enhance CARS imaging.
Inverse design and implementation of a wavelength demultiplexing grating coupler

Nanophotonics has emerged as a powerful tool for manipulating light on chips. Almost all of today's devices, however, have been designed using slow and ineffective brute-force search methods, leading in many cases to limited device performance. In this article, we provide a complete demonstration of our recently proposed inverse design technique, wherein the user specifies design constraints in the form of target fields rather than a dielectric constant profile, and in particular we use this method to demonstrate a new demultiplexing grating. The novel grating, which has not been developed using conventional techniques, accepts a vertical-incident Gaussian beam from a free-space and separates O-band (1300 nm) and C-band (1550 nm) light into separate waveguides. This inverse design concept is simple and extendable to a broad class of highly compact devices including frequency filters, mode converters, and spatial mode multiplexers.
Sensor Placement in Structural Control

Issues associated with the placement of sensors in structural control and reliability systems are analyzed. The sensor output is used to extract modal coordinates. Optimization procedures are used to determine the most desirable locations of the operational sensors. It is shown that modal filtering by means of spline functions is more desirable for modal coordinate extraction because of stability, robustness, and convergence considerations. Selection of the number and location of the backup sensors is considered. It is observed that an even distribution of the operational and backup sensors yields satisfactory results. However, an uneven placement of sensors diminishes the quality of the modal coordinate extraction.
Diversity-oriented synthesis: exploring the intersections between chemistry and biology

Diversity-oriented synthesis (DOS) is an emerging field involving the synthesis of combinatorial libraries of diverse small molecules for biological screening. Rather than being directed toward a single biological target, DOS libraries can be used to identify new ligands for a variety of targets. Several different strategies for library design have been developed to target the biologically relevant regions of chemical structure space. DOS has provided powerful probes to investigate biological mechanisms and also served as a new driving force for advancing synthetic organic chemistry.
Pursuit Evasion on Polyhedral Surfaces

We consider the following variant of a classical pursuit-evasion problem: how many pursuers are needed to capture a single (adversarial) evader on a closed polyhedral surface in three dimensions? The players move on the polyhedral surface, have the same maximum speed, and are always aware of each others' current positions. This generalizes the classical lion-and-the-man game, originally proposed by Rado (Littlewood in Littlewood?s miscellany, Cambridge University Press 1986), in which the players are restricted to a two-dimensional circular arena. The extension to a polyhedral surface is both theoretically interesting and practically motivated by applications in robotics where the physical environment is often approximated as a polyhedral surface. We analyze the game under the discrete-time model, where the players take alternate turns, however, by choosing an appropriately small time step $$t > 0$$t>0, one can approximate the continuous time setting to an arbitrary level of accuracy. Our main result is that four pursuers always suffice (upper bound), and that three are sometimes necessary (lower bound), for catching an adversarial evader on any polyhedral surface with genus zero. Generalizing this bound to surfaces of genus g, we prove the sufficiency of $$(4g + 4)$$(4g+4) pursuers. Finally, we show that four pursuers also suffice under the "weighted region" constraints where the movement costs through different regions of the (genus zero) surface have (different) multiplicative weights.
On the $\lambda$-Equations for Matching Control Laws

We discuss matching control laws for underactuated systems. We previously showed that this class of matching control laws is completely characterized by a linear system of first order partial differential equations for one set of variables ($\,\lambda$) followed by a linear system of first order partial differential equations for the second set of variables ($\,{\widehat g}$, $\,{\widehat V}$). Here we derive a new first order system of partial differential equations that encodes all compatibility conditions for the $\,\lambda$-equations. We give four examples illustrating different features of matching control laws. The last example is a system with two unactuated degrees of freedom that admits only basic solutions to the matching equations. There are systems with many matching control laws where only basic solutions are potentially useful. We introduce a rank condition indicating when this is likely to be the case.
Collective Decision-Making and Heterogeneity in Tastes

This article begins by proposing a random taste parameterization of a quadratic extension of the PIGLOG demand system at the household level, which is consistent with exact aggregation. This variation in tastes is a random function of household characteristics. The econometric implication is that a well-defined heteroscedastic error enters the demand system. This heteroscedasticity can be handled by a GMM technique. Using a large Canadian cross-sectional household data set and the Quadratic Almost Ideal Demand System, homoscedasticity is rejected; however, when heteroscedasticity is allowed for, there are no longer inconsistencies between the theoretical and empirical evidence, particularly with respect to the collective decision-making properties of homogeneity, SR1 symmetry, and distribution factor proportionality and linearity.
Flux growth and magnetoresistance behavior of rare earth Zintl phase EuMgSn.

Reactions of europium and tin in 1:1 Mg/Al mixed flux produce large crystals of EuMgSn. This phase crystallizes with the TiNiSi structure type in orthorhombic space group Pnma (a = 8.0849(7) A, b = 4.8517(4) A, c = 8.7504(8) A, Z = 4, R1 = 0.0137). The crystal structure features europium cations positioned between puckered hexagonal layers comprised of magnesium and tin atoms. Magnetic susceptibility measurements indicate the europium in this phase is divalent, which suggests that the compound is possibly valence-balanced as Eu(2+)Mg(2+)Sn(4-). However, EuMgSn is a metal as indicated by density of states calculations and electrical resistivity behavior. This phase exhibits antiferromagnetic ordering at T(N) = 10.9 K at low field (100 G) and the ordering temperature decreases when a higher magnetic field is applied. ac magnetization and field dependence of resistivity at 4.2 K reveal that there is a spin reorientation at 2 T, in agreement with the metamagnetic transition shown in the dc magnetization versus field data. Temperature dependence of resistivity at 2.5 T indicates that EuMgSn has a large magnetoresistance up to -30% near its magnetic ordering temperature.
Functions preserving positive definiteness for sparse matrices

We consider the problem of characterizing entrywise functions that preserve the cone of positive definite matrices when applied to every off-diagonal element. Our results extend theorems of Schoenberg [Duke Math. J. 9], Rudin [Duke Math. J. 26], Christensen and Ressel [Trans. Amer. Math. Soc., 243], and others, where similar problems were studied when the function is applied to all elements, including the diagonal ones. It is shown that functions that are guaranteed to preserve positive definiteness cannot at the same time induce sparsity, i.e., set elements to zero. These results have important implications for the regularization of positive definite matrices, where functions are often applied to only the off-diagonal elements to obtain sparse matrices with better properties (e.g., Markov random field/graphical model structure, better condition number). As a particular case, it is shown that \emph{soft-thresholding}, a commonly used operation in modern high-dimensional probability and statistics, is not guaranteed to maintain positive definiteness, even if the original matrix is sparse. This result has a deep connection to graphs, and in particular, to the class of trees. We then proceed to fully characterize functions which do preserve positive definiteness. This characterization is in terms of absolutely monotonic functions and turns out to be quite different from the case when the function is also applied to diagonal elements. We conclude by giving bounds on the condition number of a matrix which guarantee that the regularized matrix is positive definite.
Proportionality and Self-Interest

This paper offers a justification of the principle of military proportionality that is based in considerations of self-interest. By offering such a justification, I hope to vindicate the principle on the basis of the least controversial argument available. The war between Israel and Hezbollah in the summer of 2006 is used as a case study. Part 1 surveys recent work on military proportionality and suggests that the importance of this principle has increased in the age of asymmetrical warfare. Part 2 considers and rejects the traditional realist concerns about proportionality. Part 3 offers a realist rationale for adhering to the principle.
Star Formation in Disks: Spiral Arms, Turbulence, and Triggering Mechanisms

Star formation is enhanced in spiral arms because of a combination of orbit crowding, cloud collisions, and gravitational instabilities. The characteristic mass for the instability is 107M⊙ in gas and 105M⊙ in stars, and the morphology is the familiar beads on a string with 1-2 kpc separation. Similar instabilities occur in resonance rings and tidal tails. Sequential triggering from stellar pressure occurs in two ways. For short times and near distances, it occurs in the bright rims and dense knots that lag behind during cloud dispersal. For long times, it occurs in swept-up shells and along the periphery of cleared regions. The first case should be common but difficult to disentangle from independent star formation in the same cloud. The second case has a causality condition and a collapse condition and is often easy to recognize. Turbulent triggering produces a hierarchy of dense cloudy structure and an associated hierarchy of young star positions. There should also be a correlation between the duration of star formation and the size of the region that is analogous to the size-linewidth relation in the gas. The cosmological context is provided by observations of star formation in high redshift galaxies. Sequential and turbulent triggering is not yet observable, but gravitational instabilities are, and they show a scale up from local instabilities by a factor of ~3 in size and ~100 in mass. This is most easily explained as the result of an increase in the ISM turbulent speed by a factor of ~5. In the clumpiest galaxies at high redshift, the clumps are so large that they should interact with each other and merge in the center, where they form or contribute to the bulge.
Metals with small electron mean-free path: saturation versus escalation of resistivity

Abstract Resistivity of metals is commonly observed either to ‘escalate’ beyond the Ioffe–Regel limit (mean-free path l equal to lattice constant a ) or to ‘saturate’ at this point. It is argued that neither behavior is well understood, and that ‘escalation’ is not necessarily more mysterious than ‘saturation’.
Constraints of Cluster Separability and Covariance on Current Operators

Realistic models of hadronic systems should be defined by a dynamical unitary representation of the Poincare group that is also consistent with cluster properties and a spectral condition. All three of these requirements constrain the structure of the interactions. These conditions can be satisfied in light-front quantum mechanics, maintaining the advantage of having a kinematic subgroup of boosts and translations tangent to a light front. The most straightforward construction of dynamical unitary representations of the Poincare group due to Bakamjian and Thomas fails to satisfy the cluster condition for more than two particles. Cluster properties can be restored, at significant computational expense, using a recursive method due to Sokolov. In this work we report on an investigation of the size of the corrections needed to restore cluster properties in Bakamjian–Thomas models with a light-front kinematic symmetry. Our results suggest that for models based on nucleon and meson degrees of freedom these corrections are too small to be experimentally observed.
Effects of metal accessibility on catalytic performance for Pt/H-Mordenite

Exposure to water vapor of calcined precursors of 0.5% Pt/H- Mordenite catalysts before reduction induces formation of larger Pt particles after reduction, but also enhances the catalytic activity for methylcyclopentane (MCP) conversion. Adsorption of MCP in the pores of the metal-free zeolite indicates a high extent of pore filling with physisorbed MCP under reaction conditions, favoring transport limitation by single file diffusion. Quantitative analysis by TPO of the coke formed during catalysis shows that most of it is formed on acid sites. This coke swiftly fills the zeolite pores, so that only sites near the external surface are used in the steady state of the catalytic process. The beneficial effect of exposing the calcined catalyst precursor to water is therefore attributed to an enhanced accessibility of the sites during catalysis of MCP.
The mass spectral fragmentation of isoxazolyldihydropyridines

The mass spectral fragmentation of 4-isoxazolyl-1,4-dihydropyridines has been examined with the aid of linked metastable scanning. Three prominent pathways involve (i) O-N bond cleavage of the isoxazole followed by the loss of R2CN, (ii) loss of carboalkoxy from the 3- and/or 5- position of the dihydropyridine and, (iii) loss of the 4-isoxazolyl-substituent.
A note on randomized streaming space bounds for the longest increasing subsequence problem

The deterministic space complexity of approximating the length of the longest increasing subsequence of a stream of N integers is known to be @Q@?(N). However, the randomized complexity is wide open. We show that the technique used in earlier work to establish the @W(N) deterministic lower bound fails strongly under randomization: specifically, we show that the communication problems on which the lower bound is based have very efficient randomized protocols. The purpose of this note is to guide and alert future researchers working on this very interesting problem.
Nuclear Forces and Chiral Theories

Recent successes in ab initio calculations of light nuclei (A=2-6) will be reviewed and correlated with the dynamical consequences of chiral symmetry. The tractability of nuclear physics evinced by these results is evidence for that symmetry. The relative importance of three-nucleon forces, four-nucleon forces, multi-pion exchanges, and relativistic corrections will be discussed in the context of effective field theories and dimensional power counting. Isospin violation in the nuclear force will also be discussed in this context.
Oxidation of 1,2-bis-(benzenesulfonyl)hydrazine to 1,2-diphenyldisulfone

Abstract The oxidation of 1,2-bis(benzenesulfonyl)hydrazine yields diphenyldisulfone and not 1,2-bis(benzenesulfonyl)dimide as previously reported.
Maximally informative "stimulus energies" in the analysis of neural responses to natural signals.

The concept of feature selectivity in sensory signal processing can be formalized as dimensionality reduction: in a stimulus space of very high dimensions, neurons respond only to variations within some smaller, relevant subspace. But if neural responses exhibit invariances, then the relevant subspace typically cannot be reached by a Euclidean projection of the original stimulus. We argue that, in several cases, we can make progress by appealing to the simplest nonlinear construction, identifying the relevant variables as quadratic forms, or “stimulus energies.” Natural examples include non–phase–locked cells in the auditory system, complex cells in the visual cortex, and motion–sensitive neurons in the visual system. Generalizing the idea of maximally informative dimensions, we show that one can search for kernels of the relevant quadratic forms by maximizing the mutual information between the stimulus energy and the arrival times of action potentials. Simple implementations of this idea successfully recover the underlying properties of model neurons even when the number of parameters in the kernel is comparable to the number of action potentials and stimuli are completely natural. We explore several generalizations that allow us to incorporate plausible structure into the kernel and thereby restrict the number of parameters. We hope that this approach will add significantly to the set of tools available for the analysis of neural responses to complex, naturalistic stimuli.
Asymmetric syntheses of 3-amino-2-methylpentanoic acids. Configurations of the β-amino acid in majusculamide C, 57-normajusculamide C and dolastatins 11 and 12

Abstract The first synthesis of 3-amino-2-methylpentanoic acids is reported. Comparison of the synthetic 2 R ,3 S and 2 R ,3 S acids with 3-amino-2-methylpentanoic acid obtained by degradation of the antifungal depsipeptide majusculamide C indicates that majusculamide C, 57-normajusculamide C, and the antitumor agents dolastatins 11 and 12 have the 2 S ,3 R configurations at the chiral centers in their β-amino acid component.
Hypercube sandwich approach to conferencing

This paper presents a novel cascaded conference network that provides distributed processing and signal transmission among members of disjoint sets of generic send/receive devices called conferees. It assumes an online request model in which idle groups of conferees may request the formation of a conference interconnection. Once a conference is established, all conferees remain connected until the entire conference is dissolved. The Hypercube Sandwich Network (HSN) consists of two components. A bidirectional permutation network is used for routing purposes to and from a hypercube of special processing elements for the purpose of conference formation. The HSN achieves strictly nonblocking performance for N conferees using O(N√log N) processing elements, and this is shown to be tight to within a log 1/4N factor. Previous constructions required a quadratic number of processing elements for strictly nonblocking performance or could only provide wide-sense nonblocking conferencing. If the stronger requirement is made that the communication delay is logarithmic in the conference size, a simple algorithm is presented for wide-sense nonblocking conferencing in an HSN with O(N log N) processing elements.
The local circular law II: the edge case

In the first part of this article (Bourgade et al. arXiv:1206.1449, 2012), we proved a local version of the circular law up to the finest scale \(N^{-1/2+ {\varepsilon }}\) for non-Hermitian random matrices at any point \(z \in \mathbb C \) with \(||z| - 1| > c \) for any \(c>0\) independent of the size of the matrix. Under the main assumption that the first three moments of the matrix elements match those of a standard Gaussian random variable after proper rescaling, we extend this result to include the edge case \( |z|-1={{\mathrm{o}}}(1)\). Without the vanishing third moment assumption, we prove that the circular law is valid near the spectral edge \( |z|-1={{\mathrm{o}}}(1)\) up to scale \(N^{-1/4+ {\varepsilon }}\).
High-pressure low-temperature ignition behavior of syngas mixtures

Abstract Ignition properties of simulated syngas mixtures were systematically investigated at high-pressure low-temperature conditions relevant to gas turbine combustor operation using the University of Michigan Rapid Compression Facility. Pressure time history measurements and high-speed imaging of the ignition process in this facility were used to determine auto-ignition delay times and observe and characterize ignition behaviors. The simulated syngas mixtures were composed of H2 and CO with a molar ratio of 0.7, for equivalence ratios (φ) of 0.1 and 0.5, near air dilution (i.e. molar O2 to inert gas ratio of 1:3.76), with N2 as the primary diluent gas. The pressures and temperatures after compression ranged from 3–15 atm and 870–1150 K respectively. The comprehensive results of the present work combined with those from previous shocktube studies in the literature clearly illustrate the existence of both homogeneous and inhomogeneous auto-ignition behaviors at these conditions. Analysis of patterns in the ignition behaviors revealed a dependence on temperature, pressure, and equivalence ratio with distinct thermodynamic regions in which the ignition behavior is consistent and repeatable. Predicted locations of the strong ignition limit made using a criterion which compares laminar flame speed to a thermal gradient driven front propagation speed have excellent agreement with the experimental findings for each φ and an assumed gradient of 5 K/mm. Experimental validation of this unique and powerful criterion means that it can be used for a priori prediction of the strong ignition limit using basic computational simulations. The validity of this criterion is fundamentally important, quantitatively describing the roles of chemical kinetics, thermo-physical properties, and device dependent thermal characteristics in determining auto-ignition behavior. Additionally, a comparison of the measured auto-ignition delay times to predictions made using zero-dimensional homogeneous reactor modeling revealed that agreement was dependent on φ, with excellent agreement for φ = 0.1 and large discrepancies for φ = 0.5. These results indicate that while inhomogeneous ignition phenomena are not entirely avoidable by reducing equivalence ratio, the subsequent effects on the accuracy of typical auto-ignition delay time predictions may be reduced or eliminated.
Stereoselective synthesis of carbocyclic ring systems by pinacol-terminated Prins cyclizations

Studies that expand the scope of the Prins-pinacol synthesis of carbocyclic ring systems are described. The construction of cyclopentacyclooctanones by ring-enlarging cyclopentane annulations of cycloheptanone precursors is broadly examined as is the synthesis of related bicyclic ketones containing larger rings. Prins-pinacol reactions of acyclic alkenyl acetals were examined to gain insight into intrinsic stereochemical control elements in ring-enlarging cyclopentane annulations. The outcome of the carbocyclic constructions described in this report are rationalized by the mechanistic analysis we developed recently to describe Prins-pinacol constructions of tetrahydrofurans.
Hyperemesis Gravidarum: Outcomes and Complications With and Without Total Parenteral Nutrition

Objective: To evaluate the obstetric and medical complications with hyperemesis gravidarum, comparing those who were supported with total parenteral nutrition (TPN group) and those who did not receive TPN (non–TPN group). Study Design: The medical records of women with a diagnosis of hyperemesis gravidarum (ICD-9 code 643) admitted to Crouse Hospital, Syracuse, New York, between January 1995 and December 1998 were reviewed. A total of 166 subjects were identified and 192 admissions reviewed. Information was gathered for age, gestational age, gravity and parity, marital status, length of stay, and number of admissions, and a review of electrolyte, albumin, and thyroid function was performed. An assessment of pregnancy complications and outcomes was undertaken. Results: Of the cases reviewed, 16% (27/166) were treated with PN. The 2 groups were similar regarding incidence of pregnancy-related and maternal medical complications. The groups were similar when comparing objective measures, such as serum potassi...
A Second-Generation Synthesis of Polypyrrolinone Nonpeptidomimetics: Prelude to the Synthesis of Polypyrrolinones on Solid Support

A second-generation asymmetric synthesis of polypyrrolinones (3) has been achieved exploiting scalemic α-aminolactones (1) as building blocks. Imine formation between an appropriate lactone (1) and aldehyde (2), followed in turn by pyrrolinone ring construction promoted by KHMDS in the presence of 18-crown-6 and modified Swern oxidation furnished pyrrolinone aldehyde 3. This iterative, efficient three-step protocol paves the way for the synthesis of polypyrrolinones on solid support.
A total synthesis of (±)-allo-kainic acid

Abstract A total synthesis of (±)- allo -kainic acid is outlined. The strategy incorporates a [3+2] dipolar cycloaddition of an azomethine ylid to establish the requisite pyrrolidine stereochemistry.