cssi/SciSciGPT-SciSciNet huggingface dataset:
Optical Alignment Of A 0.5 Meter Ultra-Violet Spectrometer For Apollo 17

A 0.5 m Ebert spectrometer of high sensitivity (Figure 1) was de-signed, fabricated and calibrated by the Johns Hopkins University. It was mounted on Apollo 17 for research on the ultra-violet spectrum of the lunar atmosphere, with W. G. Fastie of the Physics Department as Principal Investigator. The Ultra-Violet Spectrometer (UVS) 5169 was designed for operation in the range 1175 A to 1675 X, but had zero transmission for all wavelengths in air. A method was developed for aligning subassemblies (using visible light) in such a way that the assembled instrument would be aligned in the ultra-violet to an accuracy of 2 with maximum efficiency, In the Vacuum Optical Bench (VOB), the efficiency and wavelength calibration were determined. If required, a small AX correction could then be made with a precision of 0.5 which would be verified during final VOB calibration. An alignment procedure using precision optical tooling will be described. Enough of the optical and mechanical features will be given to show how the basic objective was attained, and also how the inherent flexibility of the instrumentation proved useful in the rapid diagnosis and correction of several problems which were encountered. This program was a joint effort by the Physics Department and the Applied Physics Laboratory of the University. The UVS was mounted in the SIM bay of Apollo 17 (Figure 2), where it could be operated in several modes for specific investigations. These include observing:1. resonance re-radiation from the lunar atmosphere below the command module against the dark lunar surface just beyond the sunset line; or above the orbit by rolling the module 180°; 2. the UV reflectivity of the lunar surface under solar illumina-tion; 3. galactic Lyman Alpha (Lc)radiation scattered from the moon's surface on the night side; 4. galactic La during translunar coast; 5. the hydrogen halo around the earth during trans-lunar coast. The UVS S169 operated successfully during December 1972, with results to be published by the Principal Investigator.
Cusp Areas of Farey Manifolds and Applications to Knot Theory

This paper gives the first explicit, two-sided estimates on the cusp area of once-punctured-torus bundles, 4-punctured sphere bundles, and two-bridge link complements. The input for these estimates is purely combinatorial data coming from the Farey tessellation of the hyperbolic plane. The bounds on cusp area lead to explicit bounds on the volume of Dehn fillings of these manifolds, for example, sharp bounds on volumes of hyperbolic closed 3-braids in terms of the Schreier normal form of the associated braid word. Finally, these results are applied to derive relations between the Jones polynomial and the volume of hyperbolic knots, and to disprove a related conjecture.
GENERALIZED LONG-MOODY REPRESENTATIONS OF BRAID GROUPS

Long and Moody give a method of constructing representations of the braid groups Bn. We discuss some ways to generalize their construction. One of these gives representations of subgroups of Bn, including the Gassner representation of the pure braid group as a special case. Another gives representations of the Hecke algebra.
Pointwise estimates for relative fundamental solutions of heat equations in \({\mathbb{R} \times \mathbb{C}}\)

Let \({p : \mathbb{C} \to \mathbb{R}}\) be a subharmonic, nonharmonic polynomial and \({\tau \in \mathbb{R}}\) a parameter. Define \(\bar{Z}_{\tau p} = \frac{\partial}{\partial\bar{z}} + \tau\frac{\partial p}{\partial \bar{z}} = e^{-\tau p}\frac{\partial}{\partial\bar{z}} e^{\tau p}\) , a closed, densely defined operator on \({L^2(\mathbb{C})}\) . If \({\square}_{\tau p}=\bar{Z}_{\tau p}\bar{Z}_{\tau p}^{*}\) and \({\square}_{\tau p}=\bar{Z}_{\tau p}^{*}\bar{Z}_{\tau p}\) , we solve the heat equations \({\partial_s u + \tilde{\square}_{\tau p} u=0}\) , u(0,z) = f(z) and \({\partial_s \tilde{u} + \tilde{\square}_{\tau p} \tilde{u}=0}\) , \({\tilde{u}(0,z) = \tilde{f}(z)}\) . We write the solutions via heat semigroups and show that the solutions can be written as integrals against distributional kernels. We prove that the kernels are C∞ off of the diagonal {(s, z, w) : s = 0 and z = w} and find pointwise bounds for the kernels and their derivatives.
Temperature Variation and Heat Transfer in Triangular Grooves with an Evaporating Film

A mathematical model for the evaporating heat transfer coefe cient and temperature variation along the axial direction of a grooved plate has been developed. The model includes the effects of the capillaryinduced e ow in the grooves caused by the surface tension, the two-dimensional heat conduction occurring in the wall and liquid e lm, and the e ow and evaporation of the thin e lm caused by the disjoining pressure and surface tension in the thin e lm region. The results obtained from this model indicate that if a constant heat e ux boundary condition is applied, the heat transfer coefe cient will decrease and the wall temperature will increase along the axial direction. In addition, the apparent contact angle increases with increasing superheat, and hence, the heat transfer rate through the micro region also increases along the axial direction. Finally, it has been demonstrated that the contribution of the surface tension variation caused by temperature increases in the micro region can be neglected. This work will lead to a better understanding of the axial heat transfer coefe cient and temperature distribution on grooved surfaces, and how these parameters affect the e lm thickness.
Amine-Catalyzed Coupling of Allenic Esters to α,β-Unsaturated Carbonyls

Nucleophilic amines catalyze the 1,4-addition of allenic esters to α,β-unsaturated carbonyl compounds. The reactions proceed under mild conditions. In addition, Baylis−Hillman products serve as appropriate electrophiles for the process such that a one-pot, three-component coupling of aldehydes, acrylates, and allenic esters may be achieved.
Metal-Catalyzed Rearrangement of Homoallylic Ethers to Silylmethyl Allylic Silanes in the Presence of a Di-tert-butylsilylene Source

[reaction: see text] In examining the scope of the di-tert-butylsilylene transfer to gem-disubstituted alkenes to form silacyclopropanes, we discovered an unprecedented reaction of homoallylic ethers. When silylene transfer was performed at room temperature or above, two di-tert-butylsilylene units were incorporated into the molecule, and complete rearrangement of the carbon backbone occurred. This report describes the scope of this unique reaction as well as the mechanistic studies conducted that led to a proposed mechanism.
The failure of GCH at a degree of supercompactness

We determine the large cardinal consistency strength of the existence of a λ-supercompact cardinal κ such that fails at λ. Indeed, we show that the existence of a λ-supercompact cardinal κ such that 2λ ≥ θ is equiconsistent with the existence of a λ-supercompact cardinal that is also θ-tall. We also prove some basic facts about the large cardinal notion of tallness with closure.
Technology and staging effects on two-stage-to-orbit systems

Horizontal takeoff and landing two-stage systems with an airbreathing first stage and rocket second stage are evaluated for staging Mach numbers that range from 5 to 14. All systems are evaluated with advanced technologies being developed in the NASP Program and sized to the same mission requirements. With these advanced technologies, the two-stage systems are heavier than the single stage. The weights of the two-stage systems are closely related to staging. Using a rocket on the first stage to accelerate from the turboramjet limit of Mach 6 to Mach 10 signiificantly decreases dry weight as compared to the Mach 6-staged system. The optimum dry weight staging Mach number for the scramjet two-stage system is Mach 12. At a 40 percent weight growth (current technology level), the scramjet two-stage systems are half the weight and less sensitive to weight changes than the single stage, but still require substantial technology development in the areas of inlets, nozzles, ramjet propulsion, active cooling, and high-temperature structures.
Bounded Queries, Approximations, and the Boolean Hierarchy

This paper investigates nondeterministic bounded query classes in relation to the complexity of NP-hard approximation problems and the Boolean Hierarchy. Nondeterministic bounded query classes turn out be rather suitable for describing the complexity of NP-hard approximation problems. The results in this paper take advantage of this machine-based model to prove that in many cases, NP-approximation problems have the upward collapse property. That is, a reduction between NP-approximation problems of apparently different complexity at a lower level results in a similar reduction at a higher level. For example, if MAXCLIQUE reduces to (log n)-approximating MAXCLIQUE using many?one reductions, then the Traveling Salesman Problem (TSP) is equivalent to MAXCLIQUE under many?one reductions. Several upward collapse theorems are presented in this paper. The proofs of these theorems rely heavily on the machinery provided by the nondeterministic bounded query classes. In fact, these results depend on a surprising connection between the Boolean hierarchy and nondeterministic bounded query classes.
Performance improvement of alternators with switched-mode rectifiers

The use of a switched-mode rectifier (SMR) allows automotive alternators to operate at a load-matched condition at all operating speeds, overcoming the limitation of optimum performance at just one speed , . While use of an SMR and load matching control enables large improvements in output power at cruising speed, no extra power is obtained at idle. This document introduces a new SMR modulation strategy capable of improving alternator output power at idle speed without violating thermal or current limits of the alternator. The new modulation scheme may be implemented with simple control hardware, and without the use of expensive current or position sensors. After introducing the new modulation method, we develop approximate analytical models that establish the underlying basis for the approach. Implementation considerations are addressed, and both simulation and experimental results are provided that demonstrate the advantages of the proposed control method.
Elevated serum iron levels following administration of cisplatinum.

An increase in serum iron levels and a decrease in serum unsaturated iron binding capacity (uIBC) were noted following the administration of cisplatinum to 9 children with malignancies. The mean serum
Large Deviations for Random Trees

We consider large random trees under Gibbs distributions and prove a Large Deviation Principle (LDP) for the distribution of degrees of vertices of the tree. The LDP rate function is given explicitly. An immediate consequence is a Law of Large Numbers for the distribution of vertex degrees in a large random tree. Our motivation for this study comes from the analysis of RNA secondary structures.
Limitations of the standard gravitational perfect fluid paradigm

We show that the standard perfect fluid paradigm is not necessarily a valid description of a curved space steady state gravitational source. Simply by virtue of not being flat, curved space geometries have to possess intrinsic length scales, and such length scales can affect the fluid structure. For modes of wavelength of order or greater than such scales eikonalized geometrical optics cannot apply and rays are not geodesic. A set of wave mode rays that would all be geodesic in flat space (where there are no intrinsic length scales) and form a flat space perfect fluid would not all remain geodesic or of the perfect fluid form when the system is covariantized to curved space. Covariantizing thus entails not only the replacing of flat space functions by covariant ones, but also the introduction of intrinsic scales that were absent in flat space. In principle it is thus unreliable to construct the curved space energy–momentum tensor as the covariant generalization of a geodesic-based flat spacetime energy–momentum tensor. By constructing the partition function as an incoherent average over a complete set of modes of a scalar field propagating in a curved space background, we show that for the specific case of a static, spherically symmetric geometry, the steady state energy–momentum tensor that ensues will in general be of the form $${T_{\mu\nu}=(\rho+p)U_{\mu}U_{\nu}+pg_{\mu\nu}+\pi_{\mu\nu}}$$ where the anisotropic π μν is a symmetric, traceless rank two tensor which obeys $${U^{\mu}\pi_{\mu\nu}=0}$$ . Such a π μν type term is absent for an incoherently averaged steady state fluid in a spacetime where there are no intrinsic length scales, and in principle would thus be missed in a covariantizing of a flat spacetime T μν . While the significance of such π μν type terms would need to be evaluated on a case by case basis, through the use of kinetic theory we reassuringly find that the effect of such π μν type terms is small for weak gravity stars where perfect fluid sources are commonly used.
Ensemble analysis of adaptive compressed genome sequencing strategies.

Acquiring genomes at single-cell resolution has many applications such as in the study of microbiota. However, deep sequencing and assembly of all of millions of cells in a sample is prohibitively costly. A property that can come to rescue is that deep sequencing of every cell should not be necessary to capture all distinct genomes, as the majority of cells are biological replicates. Biologically important samples are often sparse in that sense. In this paper, we propose an adaptive compressed method, also known as distilled sensing, to capture all distinct genomes in a sparse microbial community with reduced sequencing effort. As opposed to group testing in which the number of distinct events is often constant and sparsity is equivalent to rarity of an event, sparsity in our case means scarcity of distinct events in comparison to the data size. Previously, we introduced the problem and proposed a distilled sensing solution based on the breadth first search strategy. We simulated the whole process which constrained our ability to study the behavior of the algorithm for the entire ensemble due to its computational intensity. In this paper, we modify our previous breadth first search strategy and introduce the depth first search strategy. Instead of simulating the entire process, which is intractable for a large number of experiments, we provide a dynamic programming algorithm to analyze the behavior of the method for the entire ensemble. The ensemble analysis algorithm recursively calculates the probability of capturing every distinct genome and also the expected total sequenced nucleotides for a given population profile. Our results suggest that the expected total sequenced nucleotides grows proportional to log of the number of cells and proportional linearly with the number of distinct genomes. The probability of missing a genome depends on its abundance and the ratio of its size over the maximum genome size in the sample. The modified resource allocation method accommodates a parameter to control that probability. The squeezambler 2.0 C++ source code is available at http://sourceforge.net/projects/hyda/ . The ensemble analysis MATLAB code is available at http://sourceforge.net/projects/distilled-sequencing/ .
Synthesis and aggregation of cationic porphyrins

Tetra(N-R-pyridinium-4-yl)porphyrin and tetra(N-R-pyridinium-3-yl)porphyrin derivatives were synthesized with R = 3, 6, and 8 carbon alkene, alcohol and carboxylic acid chains. Self-aggregation of these systems was studied at I = 0.1 using visible spectroscopy. N-Alkyl chain length and functionality were determined to play the dominant role in aggregation of the cationic porphyrins. Position of peripheral charge (meta vs. para) also influenced spectral changes and the nature of the aggregate.
Relative asymptotic behavior of pseudoholomorphic half-cylinders

In this article we study the asymptotic behavior of pseudoholomorphic half-cylinders that converge exponentially to a periodic orbit of a vector field defined by a framed stable Hamiltonian structure. Such maps are of central interest in symplectic field theory and its variants (symplectic Floer homology, contact homology, and embedded contact homology). We prove a precise formula for the asymptotic behavior of the “difference” of two such maps, generalizing results from [6, 7, 12, 15]. Using this result with a technique from [14], we then show that a finite collection of pseudoholomorphic half-cylinders asymptotic to coverings of a single periodic orbit is smoothly equivalent to solutions to a linear equation. © 2007 Wiley Periodicals, Inc.
Factors Affecting Water Blocking and Gas Flow From Hydraulically Fractured Gas Wells

This study presents results which were generated and analyzed over a 2-yr period. Several hundred computer runs were made during this project and an extensive amount of rock property data was reviewed to insure that these data were representative of tight gas reservoirs. The following conclusions reflect the combined information which was generated during the study. The reservoir properties, such as capillary pressure, change of capillary pressure in damaged zones, and relative permeability (in low permeability gas reservoirs) are primary factors in determining the behavior of a fractured well during cleanup. If the reservoir rock permeability is not damaged by frac fluid invasion, no serious water blockage to gas flow will occur when (1) the pressure drawdown is much greater than the capillary pressure in the formation, or (2) the capillary pressure and water mobility are large enough to rapidly imbibe the frac water into the formation. If the reservoir rock permeability is not damaged by frac fluid invasion, a complete water block to gas flow cannot occur; however, gas production can be severely curtailed if the pressure drawdown does not exceed the formation capillary pressure and the water mobility is so low that the frac water remains immobile nextmore » to the fracture face.« less
Reconstruction of Binary Functions and Shapes From Incomplete Frequency Information

The characterization of a binary function by partial frequency information is considered. We show that it is possible to reconstruct binary signals from incomplete frequency measurements via the solution of a simple linear optimization problem. We further prove that if a binary function is spatially structured (e.g., a general black-white image or an indicator function of a shape), then it can be recovered from very few low frequency measurements in general. These results would lead to efficient methods of sensing, characterizing and recovering a binary signal or a shape as well as other applications like deconvolution of binary functions blurred by a low-pass filter. Numerical results are provided to demonstrate the theoretical arguments.
Trimmed Opinion Pools and the Crowd's Calibration Problem

We introduce an alternative to the popular linear opinion pool for combining individual probability forecasts. One of the well-known problems with the linear opinion pool is that it can be poorly calibrated. It tends toward underconfidence as the crowd's diversity increases, i.e., as the variance in the individuals' means increases. To address this calibration problem, we propose the exterior-trimmed opinion pool. To form this pool, forecasts with low and high means, or cumulative distribution function cdf values, are trimmed away from a linear opinion pool. Exterior trimming decreases the pool's variance and improves its calibration. A linear opinion pool, however, will remain overconfident when individuals are overconfident and not very diverse. For these situations, we suggest trimming away forecasts with moderate means or cdf values. This interior trimming increases variance and reduces overconfidence. Using probability forecast data from U.S. and European Surveys of Professional Forecasters, we present empirical evidence that trimmed opinion pools can outperform the linear opinion pool. This paper was accepted by Rakesh Sarin, decision analysis.
Spectroscopic Emission Measurements Within the Blunt-Body Shock Layer in an Arcjet Flow

In the present study, radiation emanating from the freestream and shock-layer e ow over a 15.24-cmdiam, e at-faced cylinder model was measured in the NASA Ames Research Center’ s 20-MW Arcjet Facility. The test gas was a mixture of argon and air. Spatially resolved emission spectra were obtained over a 200- to 890-nm wavelength range using a charged-coupled device camera (1024 3 256 array) attached to a spectrograph. The optical system was calibrated using tungsten and deuterium radiation sources. Analytical tools were used to determine the following line-of-sight-averaged thermodynamicproperties from the calibrated spectra: 1 ) rotational temperature of the freestream and 2 ) rotational, vibrational, electronic temperatures, and species number densities within the shock layer. An analysis was performed to estimate the uncertainty bounds of the determined properties.
Nonnegative Polynomials and Sums of Squares

In the smallest cases where there exist nonnegative polynomials that are not sums of squares we present a complete explanation of this distinction. The fundamental reason that the cone of sums of squares is strictly contained in the cone of nonnegative polynomials is that polynomials of degree $d$ satisfy certain linear relations, known as the Cayley-Bacharach relations, which are not satisfied by polynomials of full degree 2d. For any nonnegative polynomial that is not a sum of squares we can write down a linear inequality coming from a Cayley-Bacharach relation that certifies this fact. We also characterize strictly positive sums of squares that lie on the boundary of the cone of sums of squares and extreme rays of the cone dual to the cone of sums of squares
Effects of mechanical strain on laser crystallized polysilicon thin film transistors and ring oscillators fabricated on stainless steel foil

Abstract In this paper the influence of mechanical tensile strain on the performance of thin film transistors (TFTs), with various channel geometries, and of ring oscillators, with 3, 7, 11, 21, and 51 number of stages and device channel lengths of 1, 4, and 8 μm, fabricated on stainless steel foil substrate is investigated. TFT parameters such as field effect mobility, threshold voltage, subthreshold slope, leakage and gate current for both n-channel, and p-channel TFTs are studied at various longitudinal tensile strain levels. For strain levels from 0.0% to 0.5%, the field effect mobility of n-channel TFTs increases while that of p-channel ones decreases as the longitudinal tensile strain increases. The field effect mobility, of both n-channel and p-channel TFTs, becomes independent of longitudinal tensile strain at strain levels greater than 0.5%. Threshold voltage and subthreshold slope of p-channel TFTs increases while that of n-channel ones does not follow a specific trend. The leakage current of both type devices tends to decrease by increasing the longitudinal tensile strain. The propagation delay, per inverter stage of a ring oscillator, is investigated at different supply voltages and tensile strain levels. The propagation delay of inverters with longer device channel length (⩾4 μm) tends to decrease while that of shorter length tends to increase as the longitudinal tensile strain increases.
An Experimental Study of the Cylindrical Langmuir Probe Response in the Transition Regime

Abstract : Experiments were performed in a highly expanded low density flowing argon plasma using both single and double probes. Results are obtained in the near free-molecule regime over a wide range of ratios of Debye length to probe radius, probe length to probe radius, and probe radius to relevant mean free path. The effect of collisions on the ion-saturation current, the retarding field electron current, the floating potential and the inferred electron temperature was investigated experimentally. An existing approximate analysis describing the collisional single probe ion-saturation current and the retarding field electron current was extended to describe the collisional double probe characteristic and magnitude of the single probe floating potential. (Author)
The strange interplay of testamentary capacity and the doctrine of undue influence. Are we protecting older testators or overriding individual preferences

The undue influence doctrine paradoxically supports freedom of testation by permitting individuals of marginal mental capacity to write valid wills by providing courts with an alternate avenue of intervention. If the doctrine did not exist, courts could invalid wills in these cases only by finding that the individual lacked testamentary capacity. But to do so would raise the level of capacity needed to write a will and so invalidate many more wills than are currently voided by a finding of undue influence. The doctrine operates as a safety valve by establishing a rule that allows courts to invalidate wills, which contain plans of distribution that the court finds shocking or objectionable. It permits a very low standard of testamentary capacity while simultaneously providing a means to nullify suspect wills of marginally capacitated testators. In the words of Gilbert and Sullivan, "A most engaging paradox." This article was published in International Journal of Law and Psychiatry, Vol. 24, Larry H. Frolik, The Strange Interplay of Testamentary Capacity and the Doctrine of Undue Influence: Are We Protecting Older Testators or Overriding Individual Preferences?, p. 253-266, Elsevier (2001).
Electron correlation in solids via density embedding theory

Density matrix embedding theory [G. Knizia and G. K.-L. Chan, Phys. Rev. Lett. 109, 186404 (2012)] and density embedding theory [I. W. Bulik, G. E. Scuseria, and J. Dukelsky, Phys. Rev. B 89, 035140 (2014)] have recently been introduced for model lattice Hamiltonians and molecular systems. In the present work, the formalism is extended to the ab initio description of infinite systems. An appropriate definition of the impurity Hamiltonian for such systems is presented and demonstrated in cases of 1, 2, and 3 dimensions, using coupled cluster theory as the impurity solver. Additionally, we discuss the challenges related to disentanglement of fragment and bath states. The current approach yields results comparable to coupled cluster calculations of infinite systems even when using a single unit cell as the fragment. The theory is formulated in the basis of Wannier functions but it does not require separate localization of unoccupied bands. The embedding scheme presented here is a promising way of employing highly accurate electronic structure methods for extended systems at a fraction of their original computational cost.
Galaxy voids in cold dark matter universes

We present predictions for numerous statistics related to the presence of voids in the distribution of galaxies in a cold dark matter model of structure formation using a semi-analytic model of galaxy formation. Our study is able to probe galaxies with masses as low as 10 9 h - 1 M O . corresponding to absolute magnitudes of M b - 5 log h = -18.1 and M r - 5 log h = -18.7. We quantify the void and underdense probability functions, distributions of nearest-neighbour distances and void sizes and compute the density profiles of voids. These results are contrasted with the expectations for dark matter (and the difference examined in terms of the galaxy/dark matter biasing relation) and are compared with analytic predictions and observational data where available. The predicted void probability functions are consistent with those measured from the Centre for Astrophysics redshift surveys given the rather large uncertainties in this relatively small (for studies of voids) observational sample. The size of the observational sample is too small to probe the bias between galaxies and dark matter that we predict. We also examine the predicted properties of galaxies existing within voids and contrast these with the general galaxy population. Our predictions are aimed at forthcoming large galaxy redshift surveys that should for the first time provide statistically accurate measures of the void population.
Gas Adsorption in Novel Environments, Including Effects of Pore Relaxation

Adsorption experiments have been interpreted frequently with simplified model geometries, such as ideally flat surfaces and slit or cylindrical pores. Recent explorations of unusual environments, such as fullerenes and metal-organic-framework materials, have led to a broadened scope of experimental, theoretical and simulation investigations. This paper reviews a number of such studies undertaken by our group. Among the topics receiving emphasis are these: universality of gas uptake in pores, relaxation of a porous absorbent due to gas uptake, and the novel phases of gases on a single nanotube, all of which studies have been motivated by recent experiments.
Hidden noise structure and random matrix models of stock correlations

We find a novel correlation structure in the residual noise of stock market returns that is remarkably linked to the composition and stability of the top few significant factors driving the returns, and, moreover, indicates that the noise band is composed of multiple sub-bands that do not fully mix. Our findings allow us to construct effective generalized random matrix theory market models that are closely related to correlation and eigenvector clustering. We show how to use these models in a simulation that incorporates heavy tails. Finally, we demonstrate how a subtle purely stationary risk estimation bias can arise in the conventional cleaning prescription.
NEIGHBORHOOD CORRELATES OF HOMICIDE TRENDS: An Analysis Using Growth-Curve Modeling

This research blends ideas and concepts from social disorganization theory with recent development in growth-curve methodology to examine the association between neighborhood structure and homicide levels over time. Using fifteen years of sequenctial data, we estimate growth-curve models that emphasize the effects of neighborhood socioeconomic and demographic characteristics on longitudinal trajectories of three types of homicide—general alteraction, felony, and domestic—in St. Louis from 1980–1994. The analyses reveal several important findings. First, initial levels of each homicide type are related in similar ways to the neighborhood characteristics. Second, trends for each subtype differ, with the shape of the trajectory depending on the type of homicide under consideration. Finally, the neighborhood factors associated with trends in general altercation, felony, and domestic killings vary for each type. The latter two points suggest the importance of disaggregating homicide rates and exploring the different factors that drive change in the patterns of these rates.
Direct adaptive control for nonlinear matrix second-order dynamical systems with state-dependent uncertainty

A direct adaptive control framework for a class of nonlinear matrix second-order dynamical systems with state-dependent uncertainty is developed. The proposed framework guarantees global asymptotic stability of the closed-loop system states associated with the plant dynamics without requiring any knowledge of the system nonlinearities other than the assumption that they are continuous and lower bounded. Generalizations to the case where the system nonlinearities are unbounded are also considered. In the special case of matrix second-order systems with polynomial nonlinearities with unknown coefficients and unknown order, we provide a universal adaptive controller that guarantees closed-loop stability of the plant states.
Engineering the voyager uranus mission

Several factors that affected the continuing expedition of Voyager 2 to Uranus are discussed. The hydrazine propellant and electrical power supplies on the spacecraft, and the radio signal strength and sun sensor and star tracker sensitivities are examined. The use of the on-board computer to steady the spacecraft and reduce image smear is described. The Voyager employs radiometric and optical data to navigate. The changes required to improve the transmission capabilities of the spacecraft and to eliminate the on-board hardware failures are analyzed.
Stabilized inversion for limited angle tomography

Many problems in applied mathematics involve recovering a function f from measurements of Lf, where L is a known operator. We study the recovery of a function from limited knowledge of its Fourier transform. The inversion of a compact operator L (for limited data) is considered from a discrete signal processing perspective. In this context, the continuous operator L is naturally viewed as the limiting case of a series of discrete operators. Since L will generally be compact and self-adjoint, its spectrum can be analyzed via standard techniques. Real-world problems are generated from discretely sampled data sets. Therefore, we believe that it is more informative to study the spectra of the discrete approximations to L rather than the spectrum of L itself. Our main tool for analyzing the spectra of these discrete approximations to L is the theory of finite Toeplitz forms, originally introduced by Szego (1915). We show that the study of these finite Toeplitz forms give us some clues concerning the construction of an accurate, stable inversion for L, even when the continuous spectra of L suggests that it is not invertible. >
On magnetic spectra of Earth and Mars

The spectral method for distinguishing crustal from core-source magnetic fields is reexamined, modified, and applied to both a comprehensive geomagnetic field model and an altitude normalized magnetic map of Mars. The observational spectra are fairly fitted by theoretical forms expected from certain elementary classes of magnetic sources. For Earth we find fields from a core of radius 3512 +/- 64 km, in accord with the seismologic core radius of 3480 km, and a crust represented by a shell of random dipolar sources at radius 6367 +/- 14 km, near the planetary mean radius of 6371.2 km. For Mars we find no sign of a core-source field, only a field from a crust represented in same way, but at radius 3344 +/- 10 km, about 46 km below the planetary mean radius of 3389.5 km, and with sources about 9.6 +/- 3.2 times stronger.
Watch Global, Cache Local: YouTube Network Traffic at a Campus Network - Measurements and Implications

Web services such as YouTube which allow the distribution of user-produced media have recently become very popular. YouTube-like services are different from existing traditional VoD services because the service provider has only limited control over the creation of new content. We analyze how the content distribution in YouTube is realized and then conduct a measurement study of YouTube traffic in a large university campus network. The analysis of the traffic shows that: (1) No strong correlation is observed between global and local popularity; (2) neither time scale nor user population has an impact on the local popularity distribution; (3) video clips of local interest have a high local popularity. Using our measurement data to drive trace-driven simulations, we also demonstrate the implications of alternative distribution infrastructures on the performance of a YouTube-like VoD service. The results of these simulations show that client-based local caching, P2P-based distribution, and proxy caching can reduce network traffic significantly and allow faster access to video clips.
Incremental constraint projection methods for variational inequalities

We consider the solution of strongly monotone variational inequalities of the form $$F(x^*)'(x-x^*)\ge 0$$ F ( x ? ) ? ( x - x ? ) ? 0 , for all $$x\in X$$ x ? X . We focus on special structures that lend themselves to sampling, such as when $$X$$ X is the intersection of a large number of sets, and/or $$F$$ F is an expected value or is the sum of a large number of component functions. We propose new methods that combine elements of incremental constraint projection and stochastic gradient. These methods are suitable for problems involving large-scale data, as well as problems with certain online or distributed structures. We analyze the convergence and the rate of convergence of these methods with various types of sampling schemes, and we establish a substantial rate of convergence advantage for random sampling over cyclic sampling.
Catalytic, Enantioselective Alkylation of α-Imino Esters: The Synthesis of Nonnatural α-Amino Acid Derivatives

Methodology for the practical synthesis of nonnatural amino acids has been developed through the catalytic, asymmetric alkylation of alpha-imino esters and N,O-acetals by enol silanes, ketene acetals, alkenes, and allylsilanes using chiral transition metal-phosphine complexes as catalysts (1-5 mol %). The alkylation products, which are prepared with high enantioselectivity (up to 99% ee) and diastereoselectivity (up to 25:1/anti:syn), are protected nonnatural amino acids that represent potential precursors to natural products and pharmaceuticals. A kinetic analysis of the catalyzed reaction of alkenes with alpha-imino esters is presented to shed light on the mechanism of this reaction.
Cross-Sectoral Governance and Performance in Service Delivery

This paper considers the determinants of effective cross-sectoral partnerships for the delivery of publicly funded services. A multivariate model of the influence on service delivery effectiveness of the inter-organizational governance arrangements, the nature of interdependencies in service delivery, the intensity of interactions, the characteristics of the constituent partners, and the characteristics of the network within which the partnerships operate is developed and empirically analyzed. Using data on 138 partnerships operating within 26 networks to provide family preservation services in a major United States county, a random-effects model is estimated. Service delivery is found to be positively impacted when roles and responsibilities are contractually defined, when partners are viewed as trustworthy, and by the extent to which decision making, information, and resources are shared. More sector diversity within the network is associated with less effective service delivery, but the effect of sector diversity in partnerships is mixed.
Spectroelectrochemistry of a urea-linked oxo-bridged iron porphyrin dimer

Abstract The electrochemical behavior of μ-oxo- N , N -bis- (5-( o -phenyl)-10,15,20-triphenylporphinatoiron(III))- urea mono hydrate, [(FF)Fe] 2 0, was investigated at a platinum electrode in both 1,2-dichloroethane and pyridine. In EtCl 2 , electroreduction of this oxo-bridged and urea-linked dimer produced a binuclear ferrous hydroxide porphyrin. This latter species could be oxidized to regenerate the μ-oxo dimer in quantitative yield. In pyridine, [(FF)Fe] 2 O underwent a chemically irreversible electroreduction producing a hexacoordinate binuclear ferrous porphyrin with pyridine occupying the axial positions of each iron atom. Oxidation of this species also produced the μ-oxo and urea-linked dimer in quantitative yield. These results are in contrast to the redox behavior of [(TPP)Fe] 2 O in these solvents. Electron transfer pathways, consistent with voltammetric and spectroelectrochemical results, are proposed for [(FF)Fe] 2 O and compared with those found for [(TPP)Fe] 2 O. The redox behavior observed for [(FF)Fe] 2 O implicates the steric constraint of the urea linkage and hydrogen bonding of the protonated bridging oxygen atom with the amide groups. This marks the first evidence of molecular environmental effects in the redox chemistry of hematin dimers.
A relationship between maximum packing of particles and particle size

Experimental data indicate that the volume fraction of particles in a packed bed (i.e. maximum packing) depends on particle size. One explanation for this is based on the idea that particle adhesion is the primary factor. In this paper, however, it is shown that entrainment and immobilization of liquid by the particles can also account for the facts.
Efficient Commitment Schemes with Bounded Sender and Unbounded Receiver

In this paper we address the problem of constructing commitment schemes where the sender is bounded to polynomial time and the receiver may be all powerful. Many known constructions for such commitment schemes are based on the hardness of factoring large integers. However, these schemes typically use integers of a special form and thus require a rather expensive initialization procedure for establishing these special-form integers. In this paper we present a scheme which is based on the hardness of factoring large integers but avoids the need of a complex initialization procedure.
Entangling the lattice clock: Towards Heisenberg-limited timekeeping

A scheme is presented for entangling the atoms of an optical lattice to reduce the quantum projection noise of a clock measurement. The divalent clock atoms are held in a lattice at a ``magic'' wavelength that does not perturb the clock frequency---to maintain clock accuracy---while an open-shell $J=1/2$ ``head'' atom is coherently transported between lattice sites via the lattice polarization. This polarization-dependent ``Archimedes' screw'' transport at magic wavelength takes advantage of the vanishing vector polarizability of the scalar, $J=0$, clock states of bosonic isotopes of divalent atoms. The on-site interactions between the clock atoms and the head atom are used to engineer entanglement and for clock readout.
Novel optical techniques for phased-array processing

The problem of feeding and controlling the radiation pattern of phased-array radar has a novel solution involving the use of fiber and Fourier optics in the system originally proposed by Koepf in 1984. We give analytical descriptions of that system and introduce novel nonlinear optical techniques to address accuracy and alignment issues.
Molecular Surface Chemistry by Metal Single Crystals and Nanoparticles from Vacuum to High Pressure.

Model systems for studying molecular surface chemistry have evolved from single crystal surfaces at low pressure to colloidal nanoparticles at high pressure. Low pressure surface structure studies of platinum single crystals using molecular beam surface scattering and low energy electron diffraction techniques probe the unique activity of defects, steps and kinks at the surface for dissociation reactions (H-H, C-H, C-C, O=O bonds). High-pressure investigations of platinum single crystals using sum frequency generation vibrational spectroscopy have revealed the presence and the nature of reaction intermediates. High pressure scanning tunneling microscopy of platinum single crystal surfaces showed adsorbate mobility during a catalytic reaction. Nanoparticle systems are used to determine the role of metal-oxide interfaces, site blocking and the role of surface structures in reactive surface chemistry. The size, shape and composition of nanoparticles play important roles in determining reaction activity and selectivity and is covered in this tutorial review.
Variational Wave Functions of a Vortex in Cyclotron Motion

In two dimensions the microscopic theory, which provides a basis for the naive analogy between a quantized vortex in a superfluid and an electron in an uniform magnetic field, is presented. A one-to-one correspondence between the rotational states of a vortex in a cylinder and the cyclotron states of an electron in the central gauge is found. Like the Landau levels of an electron, the energy levels of a vortex are highly degenerate. However, the gap between two adjacent energy levels does not only depend on the quantized circulation, but also increases with the energy, and scales with the size of the vortex.
Estimation and model selection of semiparametric copula-based multivariate dynamic models under copula misspecification

We introduce a new class of semiparametric copula-based multivariate dynamic (SCOMDY) models, which specify the conditional mean and the conditional variance of a multivariate time series parametrically, but specify the multivariate distribution of the standardized innovation semiparametrically as a parametric copula evaluated at nonparametric marginal distributions. We first study large sample properties of the estimators of SCOMDY model parameters under a misspecified parametric copula, then propose pseudo likelihood ratio (PLR) tests for model selection between two SCOMDY models with possibly misspecified copulas, and finally develop PLR tests for model selection between more than two SCOMDY models. The limiting null distributions of the PLR tests do not depend on the estimation of conditional mean and conditional variance parameters, hence are very easy to simulate. Empirical applications to three and higher dimensional daily exchange rate series indicate that a SCOMDY model with a tail-dependent copula is generally preferred.
Glassy-Winged Sharpshooters Expected to Increase Plant Disease

Abstract As it moves through California, the new pest known as glassy-winged sharpshooter (GWSS) may significantly increase the spread of plant diseases caused by the bacterium Xylella fastidiosa. ...
Observability With Random Observations

Recovery of the initial state of a high-dimensional system can require a large number of measurements. In this paper, we explain how this burden can be significantly reduced when randomized measurement operators are employed. Our work builds upon recent results from Compressive Sensing (CS). In particular, we make the connection to CS analysis for random block diagonal matrices. By deriving Concentration of Measure (CoM) inequalities, we show that the observability matrix satisfies the Restricted Isometry Property (RIP) (a sufficient condition for stable recovery of sparse vectors) under certain conditions on the state transition matrix. For example, we show that if the state transition matrix is unitary, and if independent, randomly-populated measurement matrices are employed, then it is possible to uniquely recover a sparse high-dimensional initial state when the total number of measurements scales linearly in the sparsity level (the number of non-zero entries) of the initial state and logarithmically in the state dimension. We further extend our RIP analysis for scaled unitary and symmetric state transition matrices. We support our analysis with a case study of a diffusion process.
Synthesis of deoxyadenosine adducts from the highly carcinogenic fjord region diol epoxide of benzo[c]phenanthrene

Abstract Unlike bay-region diol epoxides, the fjord-region benzo[c]phenanthrene 3,4-diol 1,2-epoxide-2(4-hydroxyl and epoxide oxygen trans) undergoes non-regioselective ring opening by both ammonia and azide anion. Adducts corresponding to a benzylic and non-benzylic SN2 ring opening by N6 of deoxyadenosine have been characterized.
MacDonald's polynomials and representations of quantum groups

In this paper we present a formula for Macdonald's polynomials for the root system A(n-1) which arises from the representation theory of quantum sl(n). This formula expresses Macdonald's polynomials via (weighted) traces of intertwining operators between certain modules over quantum sl(n). We also describe the commutative system of Macdonald's difference operators using the generators of the center of the quantum universal enveloping algebra, and use this description to prove a trace formula for generic eigenfunctions of these operators. These functions are generalized q-hypergeometric functions which are related to solutions of the quantum Knizhnik-Zamolodchikov equations.