cssi/SciSciGPT-SciSciNet huggingface dataset:
SU(6) INVARIANCE IN s-WAVE MESON--BARYON SCATTERING.

$\mathrm{SU}(6)$ has been incorporated into a simple model of a multichannel amplitude for $s$-wave scattering of mesons in the 35 representation by baryons in the 56. Symmetry breaking is introduced by making the amplitude satisfy unitarity exactly in the direct channel. The contributions to the amplitude from the crossed-channel singularities are assumed to be $\mathrm{SU}(6)$-invariant, and can be expressed in terms of four scattering lengths by the use of appropriate projection matrices. Fits of the model have been made to the threshold parameters of $\ensuremath{\pi}N$, $\mathrm{KN}$, and $\overline{K}N$ scattering. Several solutions have been found, and a comparison of calculated threshold parameters, cross sections, and phase shifts with experimental data is made. Calculations of resonances predicted by the model are performed and found to be in good agreement with experimental results.
Alternatives to axion production and detection

We consider axion production during the formation of a quark-gluon plasma in relativistic heavy-ion collisions and discuss a possible detection scheme.
Heat Capacities of Liquid Metals Above 1500 K

Heat capacity data are presented for liquid transition metals for temperatures close to the melting point and for 3000, 4000, and 5000 K. The data have been obtained by summarizing the results of levitation, exploding-wire, and drop-calorimetry measurements reported in the literature and by providing analytical estimates where experimental data are not available. The data given here are useful in assigning heat loads and predicting structure survival during extreme temperature excursions caused by nuclear, laser, or particle irradiations.
Calculation of weak matrix elements in domain-wall QCD with the DBW2 gauge action

Abstract We report the details of our ongoing quenched calculations of weak matrix elements using the combination of domain-wall fermions and the DBW2 gauge action on lattices with a −1 ∼ 3GeV. A strategy to avoid the problem of fixed topological charge is introduced in generating gauge configurations. After studying the basic run parameters and elemental quantities, we present a preliminary result for the kaon B-parameter ( B K ).
Motion on a Surface for any Positional Field of Force

The first part of the paper presents a study of the geometric proper ties of the system of trajectories generated by the motion of a particle on any constraining surface (spread of two dimensions) under any positional forces. The complete characteristic properties are derived.l Starting at any point on the surface in a given direction and with a given speed, a unique trajectory is generated, and the complete set of trajectories forms a triply infinite system of curves corresponding uniquely to a given field of force. Through a given point 0 and in a given direction, there pass oo1 trajectories. We associate with these trajectories the 1 curves obtained by orthogonal projection into the tangent plane to the sur face at 0. The first two properties derived deal with the bicircular quartic which is the locus of the foci of the osculating parabolas of the associated system. A second set of geometric properties is derived by considering the oo2 trajectories through a point 0 on the surface, and the directions through 0 in which the trajectories hyperosculate (have 4-point contact with) their corresponding geodesic circles of curvature. It is found that the hyperosculation property holds for only one trajectory in each direction, and that the corresponding locus of the centers of geodesic curvature is a conic. A final set of properties is then derived showing the relations exist ing at a point between the geodesic curvatures of the trajectories and the lines of force, and any isothermal net of curves on the surface. It is shown that the entire five properties are characteristic of the system
Regulation with anticipated learning about environmental damages

A regulator anticipates learning about the relation between environmental stocks and economic damages. For a model with linear-quadratic abatement costs and environmental damages, and a general learning process, we show analytically that anticipated learning decreases the optimal level of abatement at a given information set. If learning causes the regulator to eventually decide that damages are higher than previously thought, learning eventually increases abatement. Learning also favors the use of taxes rather than quotas. Using a model that is calibrated to describe the problem of global warming, we show numerically that anticipated learning causes a significant reduction in first period abatement and a small increase in the preference for taxes rather than quotas. Even if the regulator's initial priors about environmental damages are much too optimistic, he is able to learn quickly enough to keep the expected stock trajectory near the optimal trajectory.
Alcohol Consumption and Breast Cancer Risk in the Women's Health Study

The authors assessed the association between moderate alcohol consumption and breast cancer risk in the Women's Health Study (United States, 1992-2004). During an average of 10 years of follow-up, 1,484 cases of total breast cancer (1,190 invasive and 294 in situ) were documented among 38,454 women who, at baseline, were free of cancer and cardiovascular disease and provided detailed dietary information, including alcohol consumption, for the preceding 12 months. Higher alcohol consumption was associated with a modest increase in breast cancer risk; the multivariable relative risks for > or =30 g/day of alcohol vs. none were 1.32 (95% confidence interval (CI): 0.96, 1.82) for total breast cancer and 1.43 (95% CI: 1.02, 2.02) for invasive breast cancer. An increased risk was limited to estrogen receptor (ER)- and progesterone receptor (PR)-positive tumors; the multivariable relative risks for an increment of 10 g/day of alcohol were 1.11 (95% CI: 1.03, 1.20) for ER+PR+ tumors (804 cases), 1.00 (95% CI: 0.81, 1.24) for ER+PR- tumors (125 cases), and 0.99 (95% CI: 0.82, 1.20) for ER-PR- tumors (167 cases). The association also seemed strongest among those taking postmenopausal hormones currently, but the test for interaction was not significant. The findings from this prospective study suggest that moderate alcohol consumption increases breast cancer risk.
Devil's staircase and order without periodicity in classical condensed matter

The existence of incommensurate structures proves that a crystalline ordering is not always the most stable one for non-quantum matter. Some properties of structures which are obtained by minimizing a free energy are investigated in the Frenkel-Kontorova and related models. It is shown that an incommensurate structure can be either quasi-sinusoidal with a phason mode or built out of a sequence of equidistant defects (discommensurations) which are locked to the lattice by the Peierls force. In that situation the variation of the commensurability ratio with physical parameters forms a « complete devil's staircase » with interesting physical consequences. Some general results for all structures which minimize a free energy are given. In addition to the known crystal and incommensurate structures, the existence of a new class of structures which have local order at all scale is predicted. Properties of the new class are described in physical terms and possible applications to certain amorphous or non-stoichiometric compounds are discussed.
Microscopic reversibility and reciprocal relations for Brownian molecular machines

Chemists have made great progress in synthesizing molecules that emulate in part the remarkable properties of biological molecular motors, most especially the ability to use chemical energy to drive directed motion and do mechanical work. Here the mechanism of a molecular motor is treated as a renewal process in which the motor molecule fluctuates away from, and then returns to some arbitrary initial configurational state. During this excursion, some number of fuel molecules will have been catalytically converted to product, and the motor will have undergone some number of mechanical cycles in which work is done on the environment. The dependences of the number of catalytic and mechanical processes per renewal obey reciprocal relations for arbitrarily strong load force and chemical driving force. These relations characterize the behavior of the system far from thermodynamic equilibrium in the same way that the Onsager reciprocal relations characterize the system close to thermodynamic equilibrium.
EL ESTADO ACTUAL DEL HUEMUL (HIPPOCAMELUS BISULCUS) EN CHILE CENTRAL

La unica poblacion sobreviviente del huemul en Chile central (Los Nevados de Chillan) se encuentra en un descenso clasico hacia la extincion. Se utilizan los datos de prospecciones en terreno por el periodo entre 1975 a 2002 para estimar el tamano, la estructura espacial y la tendencia de la poblacion. Un analisis de la poblacion en 1997 arrojo un minimo de 60 huemules en 12 sitios, y una declinacion de un 58% en la poblacion durante un periodo de dos decadas. Prospecciones recientes entre 1998-2002 indican que la poblacion de huemules ha continuado disminuyendo a 40 individuos en 11 sitios, lo que representa un descenso adicional de un 33%. Desde el ano 1987, los huemules han desaparecido de 5, y posiblemente 8, sitios de habitat primario. Solamente un sitio, el del Rio Niblinto que es protegido, muestra un grupo del huemul mas o menos estable. Las amenazas al huemul y a su habitat, tal como los impactos del ganado domestico, la urbanizacion, el desarrollo recreativo, la presencia de perros domesticos y las actividades industriales siguen sin disminucion en la gran mayoria de los 26 sitios de habitat primario necesario para la recuperacion del huemul. Los datos actuales muestran claramente que una compana de conservacion mas amplia es necesaria para resguardar y recuperar la especie en Chile central. Se requieren proteger los sitios de habitat primario y los corredores conectantes de habitat del huemul. Para realizar tal objetivo, se necesitan un fuerte compromiso e inversion financiera del gobierno y del sector privado. La creacion de un nuevo parque nacional o gran reserva para el huemul y la biodiversidad en el sector de Los Nevados de Chillan, con beneficios relacionados al turismo, la educacion publica, e investigaciones cientificas, podria ayudar a atraer los recursos financieros que se necesitan para un programa exitoso de conservacion
A Dynamical Theory of Speciation on Holey Adaptive Landscapes.

abstract: A holey adaptive landscape is an adaptive landscape where relatively infrequent well‐fit combinations of genes form a contiguous set that expands throughout the genotype space. I formulate and study a series of simple models describing the dynamics of speciation on holey adaptive landscapes driven by mutation and random genetic drift. Unlike most previous models that concentrate only on some stages of speciation, the models studied here describe the complete process of speciation from initiation until completion. The evolutionary factors included are selection (reproductive isolation), random genetic drift, mutation, recombination, and migration. In these models, pre‐ and postmating reproductive isolation is a consequence of cumulative genetic change. I study possibilities for speciation according to allopatric, parapatric, peripatric, and vicariance scenarios. The results presented here, together with earlier numerical simulations, strongly suggest that rapid speciation, including simultaneous ...
The speed of adjustment and the sequencing of economic reforms

Purpose – The purpose of the paper is to review the issues involved in determining the appropriate speed of adjustment and the sequencing of economic reforms, and to develop a checklist of key guidelines for policymakers as a basis for their decision‐making process.Design/methodology/approach – The paper develops a conceptual framework based on a survey of the theoretical and empirical literature, and the practical experience of the authors in this area.Findings – The analysis in the paper shows that the optimal speed and sequence of reforms is country‐specific. But key policy considerations can help guide policymakers in the design of their reform strategy.Practical implications – The arguments favoring a shock approach or a gradual approach are not absolute. Each country has to choose the proper speed of adjustment and sequencing of reforms by examining country‐specific factors. A thorough case‐by‐case analysis is needed before a decision on the appropriate timing and sequencing of reforms can be made.O...
FINANCIAL HEDGING OF OPERATIONAL FLEXIBILITY

We extend the framework of real options to value the compound timing option owned by a manager of an industrial asset. The operator has control over the production modes, but faces operational constraints which introduce path-dependency. Moreover, the operator is only able to imperfectly hedge her income on the futures market. Using an exponential indifference valuation approach we construct a combined stochastic control formulation that merges the problems of optimal switching and indifference pricing in incomplete markets. We then present an iterative scheme for valuing operational flexibility which in particular shows additivity of indifference value over time. After discussing details of numerical implementation, we illustrate our results with several computational examples and comparative statics.
Productivity, trade and the R&D content of intermediate inputs

Abstract This paper explores a novel way to evaluate the extent to which R&D knowledge embodied in intermediate inputs correlates with productivity at the industry level. We propose the concept of the R&D content of intermediates, which represents the knowledge stock embodied in the intermediate inputs used in production. Using a sample of 32 countries and 13 manufacturing industries we compute the elasticity of industry-level TFP with respect to the R&D content of intermediates. We find that among high-R&D industries, the R&D embodied in inputs purchased from the own industry is significantly associated with industry-level TFP. In this case, both own-industry domestic inputs as well as those imported from the G5 countries are relevant. In contrast, intermediate input trade does not appear to be a significant channel of R&D diffusion among low-R&D industries.
On the α-Bromodehydrogenation of 6, 8-Dioxabicyclo[3.2.1]Octanes

Abstract The room temperature reaction of 6, 8-dioxabicyclo-[3.2.1]octanes with liquid bromine yielded 4-bromo-or 4, 4-dibromo-6, 8-dioxabicyclo [3.2.1]octanes in good yields.
Sulfur volcanism on Io

Abstract In February 2003, March 2003 and January 2004 Pele plume transmission spectra were obtained during Jupiter transit with Hubble's Space Telescope Imaging Spectrograph (STIS), using the 0.1″ wide slit and the G230LB grating. The STIS spectra covered the 2100–3100 A wavelength regions and extended spatially along Io's limb encompassing the region directly above and northward of the vent of the Pele volcano. The S2 and SO2 absorption signatures evident in these data indicate that the gas signature at Pele was temporally variable, and that an S2 absorption signature was present ∼12° from the Pele vent near 6 ± 5 S and 264 ± 15 W , suggesting the presence of another S2 bearing plume on Io. Contemporaneous with the spectral data, UV and visible-wavelength images of the plume were obtained in reflected sunlight with the Advanced Camera for Surveys (ACS) prior to Jupiter transit. The dust scattering recorded in these data provide an additional qualitative measure of plume activity on Io, indicating that the degree of dust scattering over Pele varied as a function of the date of observation, and that there were several other dust bearing plumes active during the observations. We present constraints on the composition and variability of the gas abundances of the Pele plume as well as the plumes detected by ACS and recorded within the STIS data, as a function of time.
Remarks on the conjectured log-Brunn–Minkowski inequality

Boroczky, Lutwak, Yang and Zhang recently conjectured a certain strengthening of the Brunn-Minkowski inequality for symmetric convex bodies, the so-called log-Brunn-Minkowski inequality. We establish this inequality together with its equality cases for pairs of convex bodies that are both unconditional with respect to some orthonormal basis. Applications of this fact are discussed. Moreover, we prove that the log-Brunn-Minkowski inequality is equivalent to the (B)-Theorem for the uniform measure of the cube (this has been proven by Cordero-Erasquin, Fradelizi and Maurey for the gaussian measure instead).
The Demand for Health Care Services in Rural Tanzania

This paper examines the pattern of health care demand in rural Tanzania. We distinguish between hospital and clinic-based care, in both the public and private sector using a two-level nested multinomial logit model. Own price elasticities of demand for all health care options are high, although less so for public clinics and dispensaries than other choices. However, there is a high degree of substitution between public and private care. Consequently, price increases or user fees will result in small percentage of people opting for self-treatment. Another important contribution of this paper is that the quality of medical care has large effects on health demand. This applies to the quality and availability of doctors/nurses, drugs and the clinic environment.
Patterned Self‐Assembled Monolayers: Efficient, Chemically Defined Tools for Cell Biology

Self-assembled monolayers (SAMs) of alkanethiolates on gold can be used to carefully probe immobilized biomolecule interactions with cell-surface receptors. However, due to a lack of experimental throughput associated with labor-intensive production, specialized fabrication apparatus, and other practical challenges, alkanethiolate SAMs have not had widespread use by biological researchers. In this Minireview, we investigate a range of techniques that could enhance the throughput of SAM-based approaches by patterning substrates with arrays of different conditions. Here we highlight microfluidic, photochemical, localized removal, and backfilling techniques to locally pattern SAM substrates with biomolecules and also describe how these approaches have been applied in SAM-based screening systems. Furthermore we provide perspectives on several crucial barriers that need to be overcome to enable widespread use of SAM chemistry in biological applications.
Geometry Analysis and Simulation in Shoe Centerless Grinding

In this paper, the geometry relationship of shoe centerless grinding for predicting the profile of workpiece is presented. Based on the model, critical parameters are studied. The model was compared with experimental results obtained from grinding trials.
Sliding backshorts for planar circuits

An adjustable planar imbedding circuit based on coplanar transmission lines is presented to deal with the impedance mismatch associated with the use of the Superconductor-Insulator-Superconductor tunnel junction. The planar embedding circuit is developed with movable noncontacting shorting elements that consist of thin metallic plates with optimized arrangements of rectangular holes. The rectangular holes are placed along the insulated metallic transmission line to provide a periodic variation of the line impedance. A large reflection coefficient is demonstrated with a scale model of the sliding backshort, and values of more than -0.5 dB are reported. The shorting elements are incorporated into a low-frequency tuning circuit to test the practical tuning ranges. The backshort can be used to fashion tuning stubs with variable post-fabrication electrical lengths which relaxes the design constraints of planar integrated circuits.
A note on adaptation in garch models

In the framework of the Engle-type (G)ARCH models, I demonstrate that there is a family of symmetric and asymmetric density functions for which the asymptotic efficiency of the semiparametric estimator is equal to the asymptotic efficiency of the maximum likelihood estimator. This family of densities is bimodal (except for the normal). I also chracterize the solution to the problem of minimizing the mean squared distance between the parametric score and the semiparametric score in order to search for unimodal densities for which the semiparametric estimator is likely to perform well. The LaPlace density function emerges as one of these cases.
Dielectric Properties of Fluxed Barium Titanate Ceramics with Zirconia Additions

BaTiO{sub 3} compacts, when fluxed with {lt} 2 vol% of a complex borate glass phase, were sintered to near theoretical density at temperatures {lt} 1175{degrees}C in 2 h. Microstructural analysis showed a uniform grain size {lt} 1.0 {mu}m with 0.75 wt% ZrO{sub 2} added to the flux phase as a grain growth inhibitor. TEM analysis revealed a microcrystalline grain-boundary phase with the ZrO{sub 2} resident along the grain boundaries. These samples displayed an essentially flat dielectric profile, low dissipation factors ({lt} 2%) over the range 25{degrees} to 125{degrees}C, a near linear dependence ({approx} {+-} 15%) between 25{degrees} and {minus} 55{degrees}C, and significantly increased voltage stability. X-ray diffraction analysis of these small-grained materials indicates a suppression of the tetragonal structure toward a more cubic modification.
Powering Anomalous X-Ray Pulsars by Neutron Star Cooling

Using recently calculated analytic models for the thermal structure of ultramagnetized neutron stars, we estimate the thermal fluxes from young (t~1000 yr) ultramagnetized (B~1015 G) cooling neutron stars. We find that the pulsed X-ray emission from objects such as 1E 1841-045 and 1E 2259+586, as well as many soft-gamma repeaters, can be explained by photon cooling if the neutron star possesses a thin insulating envelope of matter of low atomic weight at densities ρ<107-108 g cm−3. The total mass of this insulating layer is M~10−11-10−8 M☉.
Boundary integral method for stationary states of two-dimensional quantum systems

The boundary integral method for calculating the stationary states of a quantum particle in nano-devices and quantum billiards is presented in detail at an elementary level. According to the method, wave functions inside the domain of the device or billiard are expressed in terms of line integrals of the wavefunction and its normal derivative along the domain's boundary; the respective energy eigenvalues are obtained as the roots of Fredholm determinants. Numerical implementations of the method are described and applied to determine the energy level statistics of billiards with circular and stadium shapes and demonstrate the quantum mechanical characteristics of chaotic motion. The treatment of other examples as well as the advantages and limitations of the boundary integral method are discussed.
Stellar abundances in the early galaxy and two r-process components

We present quantitative predictions for the abundances of r-process elements in stars formed very early in the Galactic history using a phenomenological two-component r-process model based on the ^(129)I and ^(182)Hf inventory in the early solar system. This model assumes that a standard mass of the ISM dilutes the debris from an individual supernova. High-frequency supernova H events and low-frequency supernova L events are proposed in the model with characteristics determined by the meteoritic data on ^(129)I and ^(182)Hf. The yields in an H or L event are obtained from these characteristics and the solar r-process abundances under the assumption that the yield template for the high-mass (A>130) nuclei associated with ^(182)W or the low-mass (A≤130) nuclei associated with ^(127)I is the same for both the H and L events and follows the corresponding solar r-pattern in each mass region. This choice of the yield templates is justified by the regular solar-like r-process abundance pattern for Ba and higher atomic numbers observed in very metal-poor stars. The abundance of Eu, not Fe, is proposed as a key guide to the age of very metal-poor stars. We predict that stars with log e(Eu) = - 2.98 to −2.22 were formed from an ISM contaminated most likely by a single H event within the first ~ 10^7 yr of the Galactic history and should have an Ag/Eu abundance ratio less than the corresponding solar r-process value by a factor of at least 10. Many of the very metal-poor stars observed so far are considered here to have been formed from an ISM contaminated by many (∼10) r-process events. Stars formed from an ISM contaminated only by a pure L event would have an Ag/Eu ratio higher than the corresponding solar r-process value but would be difficult to find due to the low-frequency of the L events. However, variations in the relative abundances of the low- and high-mass regions should be detectable in very metal-poor stars.
Chromatic polynomials for families of strip graphs and their asymptotic limits

Abstract We calculate the chromatic polynomials P((Gs)m,q) and, from these, the asymptotic limiting functions W({G s },q)= lim n→∞ P(G s ,q) 1/n for families of n-vertex graphs (Gs)m comprised of m repeated subgraphs H adjoined to an initial graph I. These calculations of W({Gs},q) for infinitely long strips of varying widths yield important insights into properties of W(Λ,q) for two-dimensional lattices Λ. In turn, these results connect with statistical mechanics, since W(Λ,q) is the ground-state degeneracy of the q-state Potts model on the lattice Λ. For our calculations, we develop and use a generating function method, which enables us to determine both the chromatic polynomials of finite strip graphs and the resultant W({Gs},q) function in the limit n→∞. From this, we obtain the exact continuous locus of points B where W({Gs},q) is nonanalytic in the complex q plane. This locus is shown to consist of arcs which do not separate the q plane into disconnected regions. Zeros of chromatic polynomials are computed for finite strips and compared with the exact locus of singularities B . We find that as the width of the infinitely long strips is increased, the arcs comprising B elongate and move toward each other, which enables one to understand the origin of closed regions that result for the (infinite) 2D lattice.
The epidemiology of seatbelt-associated injuries

This study examined the frequency of spine and abdominal injuries to motor vehicle occupant crash victims, the relationship between the two types of injuries, and the association with restraint use. There were 303 motor vehicle occupants treated at a regional trauma center for spine and/or abdominal injuries over a 5-year period. Patients with Chance-type fractures of the lumbar spine were much more likely to be rear seat passengers and to be using a lap belt than were patients with other types of spinal injuries. Similarly, patients with hollow viscus injuries were more likely to be rear seat passengers and to be lap belted than were patients with injuries to the spleen, liver, pancreas, or kidneys. Nearly two thirds of the lumbar Chance-type fractures were associated with hollow viscus injuries, including six of seven children. This increased risk of Chance-type fractures and hollow viscus injuries was associated with increased use of lap-belt seat restraints in the population.
EDP certification: is it necessary?

There is a movement afoot within the computer industry which will have a great impact on EDP personnel. Much literature has been published which concerns itself with EDP personnel certification. The formation of the Institute for Certification of Computer Professionals (ICCP) in August, 1973, has certainly triggered a large amount of discussion within the EDP community. In reality, everyone seems to be for certification and the prestigious distinction of being called "Professional." So it's everyone to the bandwagon! At a glance, it appears that our EDP certification bandwagon is charging ahead---the certification movement is straining at the harness, the bandwagon is creating dust clouds and recklessly moving forward and the computer passengers are frantically waving for forward motion. In essence, everything is moving forward except for one thing, the wheels---and they are going backwards, thus indicating that the certification base has not been firmly established. Is this the true posture of the EDP profession and its certification movement? Before proceeding with a grand and glorious certification program, it might be well at this time to ask a few important questions. One of which might be "Is EDP certification necessary?"
V−A constraint on a product of R-parity violating couplings

We study in the framework of R-parity violating supersymmetric theories the effect of R-parity violation due to the operator LiLjEk on the (V−A) structure of the muon decay. The precisely measured muon decay parameters can constrain a product of R-parity violating couplings: |λ232λ131|<0.022 at the 90% CL, which is complementary to the previous limits obtained by the e-μ universality in τ decay.
Fight or Flight? Defending against Sequential Attacks in the Game of Siege

This article examines theory and behavior in a two-player game of siege, sequential attack and defense. The attacker’s objective is to successfully win at least one battle, while the defender’s objective is to win every battle. Theoretically, the defender either folds immediately or, if his valuation is sufficiently high and the number of battles is sufficiently small, then he has a constant incentive to fight in each battle. Attackers respond to defense with diminishing assaults over time. Consistent with theoretical predictions, the authors’ experimental results indicate that the probability of successful defense increases in the defenders valuation and it decreases in the overall number of battles in the contest. However, the defender engages in the contest significantly more often than predicted and the aggregate expenditures by both parties exceed predicted levels. Moreover, both defenders and attackers actually increase the intensity of the fight as they approach the end of the contest.
Local resilience of graphs

In this article, we initiate a systematic study of graph resilience. The (local) resilience of a graph G with respect to a property $\cal {P}$ measures how much one has to change G (locally) to destroy $\cal {P}$. Estimating the resilience leads to many new and challenging problems. Here we focus on random and pseudorandom graphs and prove several sharp results. © 2008 Wiley Periodicals, Inc. Random Struct. Alg., 2008
Computation of 1-D shock structure in a gas in rotational non-equilibrium using a new set of simplified Burnett equations

Abstract This paper describes the computations of hypersonic shock wave structure in a gas in rotational non-equilibrium using a newly developed simplified set of Burnett equations designated as Simplified Conventional Burnett (SCB) equations. Since the original formulation by Burnett, a number of variations to the original Burnett equations have been proposed and the differences among these variants and their merits/shortcomings have been described in the literature. A new variant is created based on the conventional Burnett equations for hypersonic flows by neglecting terms that are inversely proportional to the Mach number. This simplified set of conventional Burnett equations is linearly stable for small disturbances in contrast to the conventional Burnett equations which suffer from Bobylev instability. To simulate the rotational non-equilibrium effect in a diatomic gas, both the Navier–Stokes (NS) and the SCB equations are modified by including a rotational non-equilibrium relaxation model. The flow variables (density, translational and rotational temperature) in a typical 1-D shock at different Mach numbers (1.2, 5, and 10) in Nitrogen are computed using SCB and NS equations and are compared with the DSMC results. SCB calculations are in close agreement with the DSMC results at high Mach numbers.
Thoracoscopic Transmyocardial Laser Revascularization

Transmyocardial laser revascularization has been used to treat patients with end-stage coronary artery disease and severe disabling angina. Typically, the operative approach is through a left anterior thoracotomy. I report a case of transmyocardial laser revascularization performed thoracoscopically.
Constrained and Unconstrained Propeller Blade Optimization

Propeller optimization by means of calculus of variations is addressed in this paper. A procedure for deriving the Euler–Lagrange equations for both unconstrained and constrained propeller blade-twist optimization is presented. This same procedure can be followed to optimize other geometric parameters, but blade twist is considered here to investigate the feasibility of a variable-twist propeller blade. Results from unconstrained twist optimization show that, regardless of the operating condition (takeoff, climb, or cruise), the maximum efficiency occurs at significantly lower power coefficients than what a propeller will be required to absorb. Constrained optimization supports this observation by showing that, for each operating condition, a power constraint lowers the propeller efficiency. Twist distributions obtained from constrained optimization for each of the three operating conditions differ significantly from one another, but it is shown that the effect on performance is insignificant. This leads ...
A systemic approach to managing risks of SoS

As part of this, we identified some of the possible constituents of the systemic risk of SoS. It is valuable to note that the constituents could vary from case-to-case and are also time-dependent due to the dynamic nature of SoS and the environment in which it operates. Furthermore, the authors pointed out the importance of the application of systemic risk in the SoS domain and thus understanding the interconnectedness between the various constituents.
Knot Floer homology of Whitehead doubles

In this paper we study the knot Floer homology invariants of the twisted and untwisted Whitehead doubles of an arbitrary knot, K . A formula is presented for the filtered chain homotopy type of b HFK.D .K;t// in terms of the invariants for K , where D .K;t/ denotes the t ‐twisted positive (resp. negative)-clasped Whitehead double of K . In particular, the formula can be used iteratively and can be used to compute the Floer homology of manifolds obtained by surgery on Whitehead doubles. An immediate corollary is that . DC.K;t//D1 if t 0 are not smoothly slice. Another corollary is a closed formula for the Floer homology of the three-manifold obtained by gluing the complement of an arbitrary knot, K , to the complement of the trefoil.
Large-determinant sign matrices of order 4k+1

The Hadamard maximal determinant problem asks for the largest nxn determinant with entries +/-1. When n=1(mod4), the maximal excess construction of Farmakis and Kounias [The excess of Hadamard matrices and optimal designs, Discrete Math. 67 (1987) 165-176] produces many large (though seldom maximal) determinants. For certain small n, still larger determinants have been known; e.g., see [W.P. Orrick, B. Solomon, R. Dowdeswell, W.D. Smith, New lower bounds for the maximal determinant problem, arXiv preprint math.CO/0304410]. Here, we define ''3-normalized''nxn Hadamard matrices, and construct large (n+1)x(n+1) determinants from them. Our constructions give most of the previous ''small n'' records, and set new records when n=37,49,65,73,77,85,89,93,97, and 101, most of which exceed the reach of the maximal excess technique. We suspect that our n=37 determinant, 72x9^1^7x2^3^6 is best possible.
Multibody System Analysis Based on Hamilton' s Weak Principle

The double pendulum, a simple system that exhibits complex dynamics, is used to demonstrate a method based on Hamilton’ s weak principle (HWP) for assembling and solving the maximum coordinate set equations for a multibody system. Results calculated using HWP are compared to a reference solution obtained by integrating the ordinary differential equations (ODE) in minimum coordinate set form. The HWP solution is shown to be comparable to the ODE solution in accuracy and computational efe ciency. These results suggest an alternative architecture for multibody system analysis, which implements the maximum coordinate set form of the system equations, and a simple, efe cient, and robust solution algorithm.
Recognizing activities and spatial context using wearable sensors

We introduce a new dynamic model with the capability of recognizing both activities that an individual is performing as well as where that individual is located. Our approach is novel in that it utilizes a dynamic graphical model to jointly estimate both activity and spatial context over time based on the simultaneous use of asynchronous observations consisting of GPS measurements, and a small mountable sensor board. Joint inference is quite desirable as it has the ability to improve accuracy of the model and consistency of the location and activity estimates. The parameters of our model are trained on partially labeled data. We apply virtual evidence to improve data annotation, giving the user high flexibility when labeling training data. We present results indicating the performance gains achieved by virtual evidence for data annotation and the joint inference performed by our system.
Using Indirect Turbulence Measurements for Real-Time Parameter Estimation in Turbulent Air

The use of indirect turbulence measurements for real-time estimation of parameters in a linear longitudinal dynamics model was studied. It is shown that measuring the atmospheric turbulence makes it possible to treat the turbulence as a measured explanatory variable in the parameter estimation problem. Commercial off-the-shelf sensors were researched and evaluated, then compared to air data booms. Frequency-dependent upwash and time delay were identified and studied as sources of colored noise in the explanatory variables resulting from typical turbulence measurement techniques. The resulting upwash and time delay corrections were analyzed and compared to previous time shift dynamic modeling research. Simulation data as well as flight test data in atmospheric turbulence were used to verify the time delay behavior. Recommendations are given for follow-on flight research and instrumentation.
Synthesis of C-nucleosides designed to participate in triplex formation with native DNA: specific recognition of an A:T base pair in DNA.

We have previously described a system of 2-aminoquinoline- and 2-aminoquinazoline-based C-deoxynucleosides (TRIPsides) that are designed to be incorporated into oligomers that can specifically bind in the major groove via Hoogsteen base pairing to any sequence of native DNA. The four TRIPsides are termed antiGC, antiCG, antiTA, and antiAT with respect to the Watson−Crick base pair targets that they bind. The first three TRIPsides have been prepared, characterized, and shown to form stable and sequence-specific triplexes. In the present study, we describe the preparation of two molecules, 2-amino-4-(2‘-deoxy-β-d-ribofuranosyl)quinazoline (7) and 2-amino-6-fluoro-4-(2‘-deoxy-β-d-ribofuranosyl)quinoline (14), that can serve as the remaining antiAT TRIPside. The phosphoramidites of 7 and 14 were prepared, but only the latter was successfully incorporated into DNA oligomers. It is demonstrated using UV−visible melting experiments that 14 forms sequence-specific intramolecular triplets with A:T base pairs at ph...
Sound generated by instability wave/shock-cell interaction in supersonic jets

Broadband shock-associated noise is an important component of the overall noise generated by modern airplanes. In this study, sound generated by the weakly nonlinear interaction between linear instability waves and the shock-cell structure in supersonic jets is investigated numerically in order to gain insight into the broadband shock-noise problem. The model formulation decomposes the overall flow into a mean flow, linear instability waves, the shock-cell structure and shock-noise. The mean flow is obtained by solving RANSequations with a k-e model. Locally parallel stability equations are solved for the shock structure, and linear parabolized stability equations are solved for the instability waves. Then, source terms representing the instability wave/shock-cell interaction are assembled and the inhomogeneous linearized Euler equations are solved for the shock-noise.Three cases are considered, a cold under-expanded Mj = 1.22 jet, a hot under-expanded Mj = 1.22 jet, and a cold over-expanded Mj = 1.36 jet.Shock-noise computations are used to identify and understand significant trends in peak sound amplitudes and radiation angles. The peak sound radiation angles are explained well with the Mach wave model of Tam & Tanna J. Sound Vib. Vol. 81, 1982, p. 337). The observed reduction of peak sound amplitudes with frequency correlates well with the corresponding reduction of instability wave growth with frequency. However, in order to account for variation of sound amplitude for different azimuthal modes, the radial structure of the instability waves must be considered in additionto streamwise growth. The effect of heating on the Mj = 1.22 jet is shown to enhance the sound radiated due to the axisymmetric instability waves while the other modesare relatively unaffected. Solutions to a Lilley–Goldstein equation show that soundgenerated by ‘thermodynamic’ source terms is small relative to sound from ‘momentum’ sources though heating does increase the relative importance of the thermodynamic source. Furthermore, heating preferentially amplifies sound associated with the axisymmetric modes owing to constructive interference between sound from the momentumand thermodynamic sources. However, higher modes show destructive interference between these two sources and are relatively unaffected by heating.
The Simplest Solution to an Underdetermined System of Linear Equations

Consider a d times n matrix A, with d < n. The problem of solving for x in y = Ax is underdetermined, and has infinitely many solutions (if there are any). Given y, the minimum Kolmogorov complexity solution (MKCS) of the input x is defined to be an input z (out of many) with minimum Kolmogorov-complexity that satisfies y = Az. One expects that if the actual input is simple enough, then MKCS will recover the input exactly. This paper presents a preliminary study of the existence and value of the complexity level up to which such a complexity-based recovery is possible. It is shown that for the set of all d times n binary matrices (with entries 0 or 1 and d < n), MKCS exactly recovers the input for an overwhelming fraction of the matrices provided the Kolmogorov complexity of the input is O(d). A weak converse that is loose by a log n factor is also established for this case. Finally, we investigate the difficulty of finding a matrix that has the property of recovering inputs with complexity of O(d) using MKCS
Theory of Aces: Fame by Chance or Merit?

ABSTRACT We study empirically how fame of WWI fighter-pilot aces, measured in numbers of web pages mentioning them, is related to their achievement or merit, measured in numbers of opponent aircraft destroyed. We find that on average fame grows exponentially with achievement; to be precise, there is a strong correlation (∼ 0.7) between achievement and the logarithm of fame. At the same time, the number of individuals achieving a particular level of merit decreases exponentially with the magnitude of the level, leading to a power-law distribution of fame. A stochastic model that can explain the exponential growth of fame with merit is also proposed.
Single-Molecule Observation of Long Jumps in Polymer Adsorption

Single-molecule fluorescence imaging of adsorption onto initially bare surfaces shows that polymer chains need not localize immediately after arrival. In a system optimized to present limited adsorption sites (quartz surface to which polyethylene glycol (PEG) chains adsorb from aqueous solution at pH 8.2), we find that some chains diffuse back into bulk solution and readsorb at some distance away, sometimes multiple times before they either localize at a stable position or diffuse away into bulk solution. This mechanism of surface diffusion is considerably more rapid than the classical model in which adsorbed polymers crawl on surfaces while the entire molecule remains adsorbed, suggesting the conceptual generality of a recent report (Phys. Rev. Lett. 2013, 110, 256101) but in a new experimental system and with comparison of different chain lengths. We find the trajectories with jumps to follow a truncated Levy distribution of step size with limiting slope −2.5, consistent with a well-defined, rapid surfa...
Cohabitation, nonmarital childbearing, and the marriage process

Past work on the relationship between cohabitation and childbearing shows that cohabitation increases fertility compared to being single and does so more for intended than unintended births. Most work in this area however does not address concerns that fertility and union formation are joint processes and that failing to account for the joint nature of these decisions can bias estimates of cohabitation on childbearing. For example cohabitors may be more likely to plan births because they see cohabitation as an acceptable context for childbearing; alternatively they may have an underlying higher propensity to marry than their single counterparts. In this paper I use a modeling approach that accounts for the stable unobserved characteristics of women common to nonmarital fertility and union formation as a way of estimating the effect of cohabitation on nonmarital fertility net of cohabitors potentially greater likelihood of marriage. I distinguish between intended and unintended fertility to better understand variation in the perceived acceptability of cohabitation as a setting for childbearing. U.S. data show that accounting for unmeasured heterogeneity reduces the estimated effect of cohabitation on intended childbearing outside of marriage by up to 50% depending on race/ethnicity. These results speak to cohabitations evolving place in the family system suggesting that cohabitation may be a step on the way to marriage for some but an end in itself for others. (authors)
Searching for Failed Supernovae with Astrometric Binaries

Stars in the mass range 8 MdMd30 Mare thought to end their lives as luminous supernovae that leave behind a neutron star. However, if a substantial fraction of these stars instead ended as black hole rem- nants, without producing a supernova (a '' failed '' supernova), how would one know? We show that, under plausible assumptions, the Hipparcos catalog should contain � 30ffail astrometric binaries with black hole companions, where ffail is the fraction of supernovae that fail. Since no black hole astrometric binaries are found in Hipparcos, one might like to conclude that such failed supernovae are very rare. However, the most important assumption required for this argument, the initial companion mass function (ICMF) of G stars (the majority of Hipparcos stars) in the high-mass companion regime, is without any observational basis. We show how the ICMF of G stars can be measured using future space-based astrometric missions, thereby per- mitting an accurate measurement of the rate of supernovae that fail. Subject headings: astrometry — binaries: general — stars: neutron — supernovae: general On-line material: color figures