cssi/SciSciGPT-SciSciNet huggingface dataset:
Benefits of Precision Scheduling and Spacing for Arrival Operations

Advances in arrival scheduling and controller aids for spacing have the potential benefits of reducing aircraft delays and increasing airport arrival throughput. Schedulers use fixed arrival paths to estimate aircraft’s time-to-fly and assign them arrival slots based on the required separation with a buffer. Concepts that reduce arrival time uncertainty can take advantage of advanced scheduling with smaller spacing buffers. These concepts have been successfully demonstrated with a handful of near- to midterm traffic demand scenarios and technologies using spacing buffers as low as 0.3 n mile. The analysis published here characterizes the observed arrival spacing behavior of 29 runways at 15 airports in eight of the busiest terminal areas across the United States during 32–60 days worth of traffic. The typical observed instrument arrival buffers ranging from 0.5 to 1.5 n mile would equate to roughly a 10–20% increase in runway arrival capacity if buffers were reduced to 0.3 n mile. The effect of fixed arri...
Probing the Reionization History Using the Spectra of High-Redshift Sources

We quantify and discuss the footprints of neutral hydrogen in the intergalactic medium (IGM) on the spectra of high-redshift (z ~ 6) sources, using mock spectra generated from hydrodynamical simulations of the IGM. We show that it should be possible to extract relevant parameters, including the mean neutral fraction in the IGM and the radius of the local cosmological Stromgren region, from the flux distribution in the observed spectra of distant sources. We focus on quasars, but a similar analysis is applicable to galaxies and gamma-ray burst (GRB) afterglows. We explicitly include uncertainties in the spectral shape of the assumed source template near the Lyα line. Our results suggest that a mean neutral hydrogen fraction, xH, of unity can be statistically distinguished from xH ≈ 10-2 by combining the spectra of tens of bright (M ≈ -27) quasars. Alternatively, the same distinction can be achieved using the spectra of several hundred sources that are ~100 times fainter. Furthermore, if the radius of the Stromgren sphere can be independently constrained to within ~10%, this distinction can be achieved using a single source. The information derived from such spectra will help in settling the current debate as to what extent the universe was reionized at redshifts near z ~ 6.
Design and implementation of a next-generation software interface for on-the-fly quantum and force field calculations in automated reaction mechanism generation

Abstract A software interface for performing on-the-fly quantum and force field calculations has been developed and integrated into RMG, an open-source reaction mechanism generation software package, to provide needed estimates of thermodynamic parameters. These estimates based on three-dimensional molecular geometries bypasses the traditional group-additivity-based approach, which can suffer from lack of availability of necessary parameters; this issue is particularly evident for polycyclic species with fused rings, which would require ad hoc ring corrections in the group-additivity framework. In addition to making extensive use of open-source tools, the interface takes advantage of recent developments from several fields, including three-dimensional geometry embedding, force fields, and chemical structure representation, along with enhanced robustness of quantum chemistry codes. The effectiveness of the new approach is demonstrated for a computer-constructed model of combustion of the synthetic jet fuel JP-10. The interface also establishes a framework for future improvements in the chemical fidelity of computer-generated kinetic models.
Surface plasmon polaritons on metallic surfaces.

A unified theoretical study of surface plasmon polaritons on flat metallic surfaces and interfaces is undertaken to clarify the nature of these electromagnetic waves, conditions under which they are launched, and the restrictions imposed by Maxwell’s equations that ultimately determine the strength of the excited plasmons. Finite Difference Time Domain computer simulations are used to provide a clear picture of the electromagnetic field distribution and the energy flow profile in a specific situation. The examined case involves the launching of plasmonic waves on the entrance facet of a metallic host perforated by a subwavelength slit, and the (simultaneous) excitation of the slit’s guided mode.
The Ripper Project. Modern science solving mysteries of history.

Modern scientific techniques may be applied to solve historical--even ancient--mysteries. Many such mysteries have been studied by forensic scientists, including anthropologists. One example is the recent examination of the artifacts and grave sites at the Little Bighorn in Montana, the scene of the battle between General George A. Custer's troops and the Northern Plains Indian tribes. Similarly, skeleton remains of the Indian tribes of the Pre-Columbian and Columbian periods have been studied to answer many questions regarding life and death in those early civilizations. The Ripper Project began as a research activity of the Milton Helpern International Center for the Forensic Sciences at Wichita State University Wichita, Kansas, in 1981, after the concept had been discussed in a night session during the annual meeting of the American Academy of Forensic Sciences in Los Angeles. These century-old serial murders of five prostitutes--The Whitechapel Murders--in London in 1888 were discussed in great detail from the standpoints of the forensic pathologist, the forensic psychiatrist, the criminalist, the forensic historian, and the forensic dentist. The information gained during this phase of the project plus the advances made possible by the development of criminal personality profiling by the FBI led to the present status of this project, which was recently discussed in a live telecast, and which is the subject of this article. Language: en
Gauge-Invariant Fields in the Temporal Gauge, Coulomb-Gauge Fields, and the Gribov Ambiguity

We examine the relation between Coulomb-gauge fields and the gauge-invariant fields constructed in the temporal gauge for two-color QCD by comparing a variety of properties, including their equal-time commutation rules and those of their conjugate chromoelectric fields. We also express the temporal-gauge Hamiltonian in terms of gauge-invariant fields and show that it can be interpreted as a sum of the Coulomb-gauge Hamiltonian and another part that is important for determining the equations of motion of temporal-gauge fields, but that can never affect the time evolution of "physical" state vectors. We also discuss multiplicities of gauge-invariant temporal-gauge fields that belong to different topological sectors and that, in a previous work, were shown to be based on the same underlying gauge-dependent temporal-gauge fields. We argue that these multiplicities of gauge-invariant fields are manifestations of the Gribov ambiguity. We show that the differential equation that bases the multiplicities of gauge-invariant fields on their underlying gauge-dependent temporal-gauge fields has nonlinearities identical to those of the "Gribov" equation, which demonstrates the nonuniqueness of Coulomb-gauge fields. These multiplicities of gauge-invariant fields — and, hence, Gribov copies — appear in the temporal gauge, but only with the imposition of Gauss' law and the implementation of gauge invariance; they do not arise when the theory is represented in terms of gauge-dependent fields and Gauss' law is left unimplemented.
Near horizon geometry and black holes in four-dimensions

Abstract A large class of extremal and near-extremal four-dimensional black holes in M-theory feature near-horizon geometries that contain three-dimensional asymptotically anti-de Sitter spaces. Globally, these geometries are derived from AdS3 by discrete identifications. The microstates of such black holes can be counted by exploiting the conformal symmetry induced on the anti-de Sitter boundary, and the result agrees with the Bekenstein-Hawking area law. This approach, pioneered by Strominger, clarifies the physical nature of the black hole microstates. It also suggests that recent analyses of the relationship between boundary conformal field theory and supergravity can be extended to orbifolds of AdS spaces.
A direct synthesis of trans 2-arylbenzocyclobutenol, a potential intermediate for podophyllotoxin synthesis: Use of lda for benzyne formation and trapping

Abstract Treatment of m -alkoxyaryl bromides with LDA in THF produces the corresponding aryne which can be trapped intramolecularly by an anion α to a nitrile to produce a substituted benzocyclobutenyl nitrile, the precursor of a trans arylbenzocyclobutenol potentially useful for podophyllotoxin synthesis.
Temperatures in a Gas Turbine Vaporizer at Near Idle Engine Conditions

The work is a laboratory investigation of the effect of different liquids and liquid flow rates on the metal temperature of a gas turbine T vaporizer. Most of the experimentation was carried out using JP5. A limited number of runs using Diesel Fuel Marine and calibration runs using water provided additional data for different fluids. Conditions that approach local liquid depletion inside the vaporized were identified by monitoring local overheating of the vaporizer metal. Because of apparatus limitations, testing was carried out only at vaporizer pressure and liquid flow rates approaching idle engine operation. An experimental correlation was developed allowing estimation of the mean vaporizer temperature as a function of input conditions and fluid properties
Reduction of NOx Formation by Water Sprays in Strained Two-Stage Flames

Staged combustion can be employed to reduce the formation of CO and NO{sub x}, stabilize the flame, decrease the flame temperature, and create better working conditions in gas turbine combustors. To help understand influences of partial premixing and addition of water on NO{sub x} formation, the authors study two-stage flames in a counterflow spray burner. This paper reports experimental and theoretical results concerning two-stage combustion in which one feed stream is composed of a fuel-rich mixture of methane and air and the other is air. Water sprays are added to the air stream. This two-phase laminar counterflow configuration exhibits a green premixed flame, a blue diffusion flame, and a vaporization plane. All three are flat and parallel. The separation distances between them decrease with increasing equivalence ratio and strain rate. Flow visualization is provided through illumination by an argon ion laser sheet, velocity fields and spray structure are measured by a phase-doppler particle analyzer, concentration fields of major stable species are measured by gas chromatography of samples withdrawn from the flame, and temperature fields are measured by a thermocouple. Numerical integrations that employ a recent chemical-kinetic data base are performed to model the flame structure and NO{sub x} formation. Comparisonsmore » of experimental results with numerical predictions are made to test agreement. This work provides information on hydrocarbon combustion in both premixed flames and diffusion flames, indicates how NO{sub x} is formed in fuel-rich flames, and suggests how the pollutants can be reduced.« less
Study of Errors in Strong Gravitational Lensing

We examine the accuracy of strong gravitational lensing determinations of the mass of galaxy clusters by comparing the conventional approach with the numerical integration of the fully relativistic null geodesic equations in the case of weak gravitational perturbations on Robertson-Walker metrics. In particular, we study spherically symmetric, three-dimensional singular isothermal sphere models and the three-dimensional matter distribution of Navarro and coworkers which are both commonly used in gravitational lensing studies. In both cases we study two different methods for mass-density truncation along the line of sight: hard truncation and conventional (no truncation). We find that the relative error introduced in the total mass by the thin-lens approximation alone is less than 0.3% in the singular isothermal sphere model and less than 2% in the model of Navarro and coworkers. The removal of hard truncation introduces an additional error of the same order of magnitude in the best case and up to an order of magnitude larger in the worst case studied. Our results ensure that the future generation of precision cosmology experiments based on lensing studies will not require the removal of the thin-lens assumption, but they may require a careful handling of truncation.
The cosmic microwave background radiation

Because angular anisotropies and spectral distortions of the cosmic microwave background radiation are judged to be inevitable at some level, in a realistic cosmological model, the evidence for spectral distortions and its theoretical implications are described. The evidence for anisotropy is then discussed, and theoretical predictions of radiation anisotropy are summarized and compared with the data available. It is found that spectral distortions at the 3-sigma level near the peak of the blackbody spectrum, although inconsistent with the predicted distortions due to Compton scattering in the early universe, are elegantly interpreted in terms of radiation from an early, pregalactic generation of massive stars which had been thermalized by a modest amount of dust at high redshift. The quadrupole anisotropy at the 4-sigma level is most simply interpreted in terms of the large-scale structure of the universe.
A numerical approach to the flux density integral for reflected sunlight

Abstract A computer model of the central receiver system must evaluate the flux density on the receiver due to sunlight reflected by the heliostats in the collector field. Several approaches are available but each has its limitations. The Monte-Carlo approach represents all of the heliostat behavior but is relatively slow in terms of CPU time and is not suitable for optimization purposes. FLASH is an analytically exact approach for flat polygonal heliostats but is slow and not applicable to dished heliostats or aureole effects. Cone optics programs evaluate the flux density by a direct numerical integration of the double integral, but this method is very slow if accuracy is required. HCOEF is a two dimensional Hermite polynomial method which is relatively fast and can be extended to include canting, focusing, solar limb, and guidance error effects. However, the polynomial approximation breaks down for near heliostats, small guidance errors, and aureole effects. The new image generators based on KGEN overcome this limitation, but running times compare to FLASH and are 3 or 4 slower than HCOEF. The new approach proposed in this study assumes isotropic gaussian guidance errors. Hence, the flux density integral reduces to several iterated single integrals which can be precalculated and stored in a table for interpolation as needed. The LBL solar telescope data are fed into a convolution integral which represents the guidance errors. Aureole effects can be switched on or off at this point. A vector of convoluted solar data is input to another integration which gives the table of normalized flux contributions. The tabular values depend on the position of the flux point with respect to an edge of the heliostat as seen in the image plane. The image map of the heliostat is linear unless ripples or irregularities occur; hence, effects due to canting and dishing can be included by a ray trace of the heliostat vertices. The use of tabular interpolation is not as fast as expected because of the time required to calculate the distance between the flux point and the image of the vertices. The accuracy of this method is limited by interpolation errors, and better results can be obtained with the same CPU time if more core is used for a larger table. It is possible to eliminate the table by introducing a Romberg type of integrator which bisects the interval until sufficient accuracy is achieved; however, this approach is inefficient unless the images are relatively small compared to the receiver. The convolution process in KGEN is fast and can be used to calculate moments for HCOEF and coefficients for FLASH which utilize the LBL data.
Interlayer exchange coupling in Fe/Cr multilayers

We investigate the origin of the long-period oscillation of the interlayer exchange coupling in Fe/Cr trilayer systems. Within the stationary phase approximation the periods of the oscillations are associated with extremal vectors of the Fermi sphere of Cr. Using a realistic tight-binding model with spin-orbit interaction we calculate the coupling strength for each extremal vector based on the spin asymmetry of the reflection amplitude for a propagating state impinging from the Cr to Fe layer. We find that for the (001) and (110) growth directions the biggest coupling strength comes from the extremal vector centered at the ellipsoid N of the Fermi surface of Cr.
Controlling Quantum Transport through a Single Molecule

We investigate multiterminal quantum transport through single monocyclic aromatic annulene molecules, and their derivatives, using the nonequilibrium Green function approach within the self-consistent Hartree-Fock approximation. We propose a new device concept, the quantum interference effect transistor, that exploits perfect destructive interference stemming from molecular symmetry and controls current flow by introducing decoherence and/or elastic scattering that break the symmetry. This approach overcomes the fundamental problems of power dissipation and environmental sensitivity that beset nanoscale device proposals.
Associative Learning in Hierarchical Self-Organizing Learning Arrays

In this paper, we introduce feedback-based associative learning in self-organized learning arrays (SOLAR). SOLAR structures are hierarchically organized networks of sparsely connected neurons that define their own functions and select their interconnections locally. This paper provides a description of neuron self-organization and signal processing. Feedforward processing is used to make necessary correlations and learn the input patterns. Discovered associations between neuron inputs are used to generate feedback signals. These feedback signals, when propagated to the primary inputs, can establish the expected input values. This can be used for heteroassociative (HA) and autoassociative (AA) learning and pattern recognition. Example applications in HA learning are given
Cyclization of aromatic polyketides from bacteria and fungi

Covering: up to the end of 2009 This review discusses the enzymatic basis of the different cyclization strategies used by bacteria and fungi in the biosynthesis of aromatic polyketides.
The equivalence of bilinear forms

Let B: I’ x V -+ F be a bilinear form on the finite dimensional vector space V over the field F. No assumptions such as symmetry or skew symmetry are made, although we assume that B is nondegenerate. Another such form C: W x W + F is equivalent to B if there is an isomorphism q~: V -+ W such that C(cpu, TV) = B(u, V) f or all u and z, in V, such a p is called an isometry of I/ and W, or more precisely of B and C. The solution of the equivalence problem for alternating forms is well known, and solutions have also been obtained for symmetric forms, and more generally for hermitian forms and quadratic forms, over special fields. It seems to be less well known that in most cases the equivalence problem for general bilinear forms has also been “solved” by J. Williamson [lo]. His work was extended by G. E. Wall [9] to the case of sesquilinear forms over a division ring. These solutions consist of associating to B first a linear transformation, called the asymmetry of B, and second a sequence b, ,..., b, of symmetric, alternating, and hermitian forms; then B N C if and only if their asymmetries are similar and b, N ci , b, N ca ,..., b, ‘v c, . Thus once one has solved the equivalence problem for the “classical” types of forms over F (and its finite extensions), the general problem of equivalence is also solved. Williamson’s work was motivated originally by probIems in linear systems of differential equations and subsequently by the problem of determining the conjugacy classes, or “normal forms” of elements of the classical groups. The connection between these conjugacy classes and equivalence classes of bilinear forms can be found in [9]. The conjugacy problem has also been worked on more directly by many people (e.g., Springer [7], Zassenhaus [ll], Cikunov [3], Milnor [5]). I p ro p ose to apply techniques similar to those employed in the conjugacy problem, especially by Milnor, to recast the
Columnar DNA Superlattices in Lamellar o-Ethylphosphatidylcholine Lipoplexes: Mechanism of the Gel-Liquid Crystalline Lipid Phase Transition

DNA arranges into rectangular columnar superlattices between interdigitated lipid bilayers in the low-temperature gel phase of the lipoplexes of the cationic o-ethylphosphatidylcholines. The interlamellar correlation in the DNA ordering is not observed within the liquid crystalline lipid phase. The gel-liquid crystalline phase transition of the lipid induces a contraction of the DNA smectic array that matches the increased positive charge density of the membrane surface caused by the interdigitated-noninterdigitated transition. The transition proceeds via an intermediate state that has an expanded lamellar repeat period.
Liquid crystals: Tangled loops and knots

Knot-shaped micrometric tubes embedded in a liquid crystal induce the formation of defect lines that loop around the knotted tubes to form knots.
Automatic Processing of Foreign Language Documents.

Experiments conducted over the last few years with the SMART document retrieval system have shown that fully automatic text processing methods using relatively simple English language analysis tools are as effective for document indexing, classification, search, and retrieval as the more elaborate manual methods normally used. The present study describes an extension of the SMART procedures to German language materials. A multilingual thesaurus is used for the analysis of documents and search requests, and tools are provided which make it possible to process English documents against German queries, and vice versa. The methods are evaluated and it is shown that the effectiveness of the mixed language processing is approximately equivalent to that of the standard process operating within a single language only.
Photoelectron Spectroscopy of Si2

In this report we discuss the photoelectron spectrum of Si2 − obtained at 355 nm. The spectrum shows a series of transitions to the low-lying triplet states of Si2 as well as transitions to the higher-lying singlet states. Several possible assignments of the anion and neutral triplet states are presented.
Infinite reduction of divisors on metric graphs

We demonstrate that the greedy algorithm for reduction of divisors on metric graphs need not terminate by modeling the Euclidean algorithm in this context. We observe that any infinite reduction has a well defined limit, allowing us to treat the greedy reduction algorithm as a transfinite algorithm and to analyze its running time via ordinal numbers. Matching lower and upper bounds on worst case running time of O(@w^n) are provided.
Synthesis and biological evaluation of Nα-(4-amino-4-deoxy-10-methylpteroyl)-DL-4,4-difluoroornithine

Nα-(4-Amino-4-deoxy-10-methylpteroyl)-dl-4,4-difluoroornithine (AMPte-dl-4,4-F2Orn, 4) was synthesized and evaluated as an inhibitor of human folylpoly-γ-glutamate synthetase (FPGS), dihydrofolate reductase (DHFR), and cell growth. Synthesis of 4 involved the use of a protected form of dl-4,4-difluoroornithine 9 which was derived from dl-4,4-difluoroglutamic acid. Biological activities of 4 were compared directly to those of the corresponding nonfluorinated compound Nα-(4-amino-4-deoxy-10-methylpteroyl)-l-ornithine (AMPte-l-Orn, 3). Although the fluorinated analogue is a potent inhibitor of DHFR, it is a poor inhibitor of FPGS. However, the compound is transported across the cell membrane and inhibits cell growth, presumably due to the inhibition of DHFR. The data obtained with the fluorinated analogue are in contrast to those of the corresponding nonfluorinated compound 3, which is a potent inhibitor of both FPGS and DHFR but shows very low cytotoxicity due to poor transport.
Using heavy quark fragmentation into heavy hadrons to determine QCD parameters and test heavy quark symmetry

Abstract We present a detailed analysis of the use of heavy quark fragmentation into heavy hadrons for testing the heavy quark effective theory through comparison of the measured fragmentation parameters of the c and b quarks. Our analysis is entirely model independent. We interpret the known perturbative evolution in a way useful for exploiting heavy quark symmetry at low energy. We first show consistency with perturbative QCD scaling for measurements done solely with c quarks. We then apply the perturbative analysis and the heavy quark expansion to relate measurements from ARGUS and LEP We place bounds on a nonperturbative quark mass suppressed parameter, and compare the values for the b and c quarks. We find consistency with the heavy quark expansion but fairly sizable QCD uncertainties. We also suggest that one might reduce the systematic uncertainty in the result by not extrapolating to low z.
Recurrence rates after EMR of large sessile serrated polyps

Background Little is known regarding the recurrence rate after EMR of large (≥20 mm) sessile serrated adenoma/polyps (SSA/Ps). Objective To compare the recurrence rate among SSA/Ps and conventional adenomas in patients referred to a specialty practice for EMR. Design Retrospective cohort study. Setting Academic hospital and a satellite surgery center. Patients A total of 362 consecutive patients referred for resection of large (≥20 mm) polyps in the colorectum. Interventions All EMRs were performed with a submucosal contrast agent. All subjects had a follow-up surveillance examination (inspection and biopsy of the EMR) at our center. Main Outcome Measurements Rates of residual polyp at follow-up examination. Results Residual polyp was identified among 8.7% of SSA/Ps compared with 11.1% for conventional adenomas ( P = .8). Limitations Retrospective design, procedures performed by a single experienced endoscopist, low number of serrated lesions. Conclusions The rate of recurrence after EMR of SSA/Ps is similar to the rate after EMR of conventional adenomas.
Separated at Birth: The Origin of the Pulsars B2020+28 and B2021+51 in the Cygnus Superbubble

High-precision astrometric data have enabled us to determine the trajectories through the Galactic potential for a growing number of pulsars. This has resulted in the discovery of a pulsar pair (B2020+28 and B2021+51) that has a common origin in the Cygnus superbubble or in one of its related OB associations at an epoch that is comparable to the spin-down ages of the pulsars. Analysis of the Galactic orbits indicates that the progenitors of the pulsars had similar masses and were in a binary system that was disrupted after the second supernova explosion. The implied pulsar birth velocities are consistent with the high velocities of neutron stars in general. The initial spin period of the pulsar that was formed in the second supernova explosion was ~200 ms. A further increase in astrometric accuracy will allow us to more tightly constrain the birth velocities and the kick velocities that were imparted by the two supernova explosions. Two additional pulsars in the sample of 24 with parallax measurements may also have originated in the Cygnus superbubble.
The case against early melting of the bulk of the Moon

Abstract Recent data suggest that the source region of mare basalts became compositionally closed at 4.42 Gy. presumably some 170 My. after the Moon accreted. Thermal-history models indicate that the outer part of the Moon could not have cooled to temperatures low enough to cause closure unless only the outer few hundred kilometers were initially molten. A total early lunar differentiation is therefore prohibited. The bulk of the Moon was therefore pristine and undifferentiated at the time of mare basalt formation. bl
Evidence for Spectropolarimetric Diversity in Type Ia Supernovae

We present single-epoch, postmaximum spectropolarimetry of four Type Ia supernovae (SNe Ia) that span a range of spectral and photometric properties: SN 2002bf and SN 2004dt exhibit unusually high-velocity (HV) absorption lines. SN 1997dt is probably somewhat subluminous, and SN 2003du is slightly overluminous. We detect polarization modulations across strong lines in all four objects, demonstrating that all are intrinsically polarized. However, the nature and degree of the polarization varies considerably. Including all SNe Ia studied thus far, the following order emerges in terms of increasing strength of line-polarization features: ordinary/overluminous < subluminous < HV SNe Ia, with the strength of the line-polarization features increasing from 0.2% in the slightly overluminous SN 2003du to 2% in both of the HV SNe Ia in our study. The most convincing explanation for the line polarization of all objects is partial obscuration of the photosphere by clumps of intermediate-mass elements forged in the explosion; the polarization characteristics of the HV SNe Ia in particular effectively rule out a simple ellipsoidal asphericity as the root cause of their line polarization. That SNe Ia are separable into different groups based on their spectropolarimetric characteristics may help narrow down progenitor possibilities and/or explosion physics. In particular, the recently proposed gravitationally confined detonation model may provide an attractive explanation for many of the observed polarization characteristics of HV SNe Ia.
Eigenvector Sky Subtraction

We develop a new method for estimating and removing the spectrum of the sky from deep spectroscopic observations. Our method does not rely on simultaneous measurement of the sky spectrum with the object spectrum. The technique is based on the iterative subtraction of continuum estimates and eigenvector sky models derived from singular value decompositions of sky spectra and sky spectra residuals. Using simulated data derived from small-telescope observations, we demonstrate that the method is effective for faint objects on large telescopes. We discuss simple methods to combine our new technique with the simultaneous measurement of sky to obtain sky subtraction very near the Poisson limit.
Heterostructure devices: A device physicist looks at interfaces

The band offsets occurring at abrupt hetero-interfaces in heterostructure devices serve as potential steps acting on the mobile carriers, in addition to the macroscopic electrostatic forces already present in homostructure devices. Incorporation of hetero-interfaces therefore offers a powerful device design parameter to control the distribution and flow of mobile carriers, greatly improving existing kinds of devices and making new kinds of devices possible. Unusual device requirements can often be met by band lineups occurring in suitable semiconductor combinations. Excellent theoretical rules exist for the semi-quantitative (< ±0.2 eV) prediction of band offsets, even unusual ones, but no quantitatively accurate (< ±l kT) purely theoretical predictive rules are currently available. Poorly-understood second-order nuisance effects, such as small interface charges and small technology-dependent offset variations, act as major limitations in device design. Suitable measurements on device-type structures can provide accurate values for interface physics parameters, but the most widely used measurements are of limited reliability, with pure I—V measurement being of least use. Many of the problems at interfaces between two III/V semiconductors are hugely magnified at interfaces between a compound semiconductor and an elemental one. Large interface charges, and a strong technology dependence of band offsets are to be expected, but can be reduced by deliberate use of certain unconventional crystallographic orientations. An understanding of such polar/nonpolar interfaces is emerging; it is expected to lead to a better understanding and control of III/V-only device interfaces as well.
mTOR and cancer: many loops in one pathway

The mammalian target of rapamycin (mTOR) is a master regulator of cell growth and division that responds to a variety of stimuli, including nutrient, energy, and growth factors. In the last years, a significant number of pieces have been added to the puzzle of how mTOR coordinates and executes its functions. Extensive research on mTOR has also uncovered a complex network of regulatory loops that impact the therapeutic approaches aimed at targeting mTOR.
The Effects of Annuities, Bequests, and Aging in an Overlapping Generations Model of Endogenous Growth

We examine the effects of introducing actuarially fair annuity markets into an overlapping generations model of endogenous growth. The complete annuitisation of agents' wealth is not, in general, dynamically optimal; the degree of annuitisation that is dynamically optimal depends nonmonotonically on the expected length of retirement and on the pay-as-you-go social security tax rate. The government has an incentive to restrict the availability of actuarially fair annuities contracts, and can often move the economy from a pay-as-you-go to a fully-funded social security system via voluntary contributions to a government sponsored, actuarially fair pension today accompanied by reductions in social security taxes tomorrow.
Theory of flux penetration into thin films with field-dependent critical current.

A theoretical analysis is presented for the critical state of an infinitely long type-II superconducting strip characterized by an arbitrary critical current density {ital J}{sub {ital c}}({ital B}). An analytical framework is developed, and numerical solutions are presented for the quasistatic current-density and flux-density profiles, as well as the hysteretic magnetization curves. The field dependence of the critical current density significantly affects the shape of the magnetization curves.
Biosafety Concerns Involving Genetically Modified Mosquitoes to Combat Malaria and Dengue in Developing Countries

-easevectorsinhumansettlementsineveryregion.Today, mosquito-transmitted diseases are presentmainlyintheequatorialbelt,posingmajorriskstohalftheworld’spopulationandcausingdiseasein700mil-lionindividualsannually.Malariaanddenguearethemostprevalent mosquito-borne infections, but West Nile virusin the Americas and chikungunya and Japanese encephali-tisinAsiaandOceaniaarerapidlyemerging.
Metal Hydride Storage for Mobile and Stationary Applications

Abstract Metal hydrides offer the possibility of a convenient and safe method for the storage of hydrogen. These compounds provide for compact storage in a form that is equal to or better than cryogenic liquid hydrogen on a volume basis. Considerable research has gone into the study of hydrides derived from rare earth, iron-titanium and magnesium alloys. The formation of these compounds is reversible and the chemistry of relevant hydrides has been discussed. Heat must be provided to decompose these compounds and release the hydrogen, while heat is liberated when the compounds are formed and must be removed to allow the hydriding reactions to proceed to completion. The iron-titanium and magnesium alloys are especially promising hydride storage media, the former in stationary applications, or where weight is not a limiting consideration, and the latter for mobile applications, Each of these materials has unique pressure-temperature characteristics and reaction kinetics which must be considered in the design of a hydrogen storage system. These special characteristics are discussed for particular applications. The results of recent work on hydrogen storage development and the engineering design of storage systems are reviewed.
A logarithmic time sort for linear size networks

A randomized algorithm that sorts on an N node network with constant valence in O(log N) time is given. More particularly, the algorithm sorts N items on an N-node cube-connected cycles graph, and, for some constant k, for all large enough a, it terminates within ka log N time with probability at least 1 - N-a.
Receptivity of Hypersonic Boundary Layers to Distributed Roughness and Acoustic Disturbances

Boundary-layer receptivity and stability of Mach 6 flows over smooth and rough seven-degree half-angle sharp-tipped cones are numerically investigated. The receptivity of the boundary layer to slow acoustic disturbances, fast acoustic disturbances, and vortical disturbances is considered. The effects of three-dimensional isolated roughness on the receptivity and stability are also simulated. The results for the smooth cone show that the instability waves are generated in the leading edge region and that the boundary layer is much more receptive to slow acoustic waves than to the fast acoustic waves. Vortical disturbances also generate unstable second modes, however the receptivity coefficients are smaller than that of the slow acoustic wave. Distributed roughness elements located near the nose region decreased the receptivity of the second mode generated by the slow acoustic wave by a small amount. Roughness elements distributed across the continuous spectrum increased the receptivity of the second mode generated by the slow and fast acoustic waves and the vorticity wave. The largest increase occurred for the vorticity wave. Roughness elements distributed across the synchronization point did not change the receptivity of the second modes generated by the acoustic waves. The receptivity of the second mode generated by the vorticity wave increased in this case, but the increase is lower than that occurred with the roughness elements located across the continuous spectrum. The simulations with an isolated roughness element showed that the second mode waves generated by the acoustic disturbances are not influenced by the small roughness element. Due to the interaction, a three-dimensional wave is generated. However, the amplitude is orders of magnitude smaller than the two-dimensional wave.
Age-related changes in structure and extracellular matrix protein expression levels in rat tendons

The musculoskeletal system (muscle–tendon–bone) demonstrates numerous age-related changes, with modifications in tendons the least well studied, although increased predisposition to tendinopathy and rupture have been reported. In order to gain insights into the basis of age-associated increase in tendon injuries, we compared Achilles and tibialis anterior tendons and myotendinous junctions (MTJs) from 3- to 5- and 22- to 25-month-old rats for underlying structure and composition. Significant decreases were observed by qRT-PCR for collagen I, III, and V mRNA expression in tendons of old rats, but immunostaining detected no apparent differences in collagen I and V expression on the protein level. Tendons of old compared with young rats had decreased mRNA expression levels of proteoglycan 4 (PRG4) and elastin (Eln), but no differences in the mRNA expression of connective tissue growth factor, TGF-beta 1, or stromal cell-derived factor 1. For PRG4, immunostaining showed good correlation with qRT-PCR results. This is the first study to show reductions in PRG4 in tendons and MTJs of old rats. Decreased PRG4 expression in tendons could result in increased tendon stiffness and may be associated with decreased activity in the elderly. The diminished collagen mRNA expression in combination with decreased PRG4 and Eln mRNA expression may be associated with increased risk of tendon injury with aging. Electronic supplementary material The online version of this article (doi:10.1007/s11357-013-9514-2) contains supplementary material, which is available to authorized users.
Acné : 1991–2001

Resume L'objectif de cette presentation est d'informer les praticiens du developpement des connaissances concernant la physiopathologie et le traitement de l'acne de 1991 a 2001. Ce rapport rend compte des meilleures donnees disponibles au moment de sa redaction, mais il convient d'etre prudent dans leur interpretation ; les resultats de futures etudes peuvent conduire a une modification des conclusions ou des recommandations presentees ici.
Market expectations, job search, and gender differences in starting pay

Search theory suggests that if a woman anticipates discriminatory treatment in the labor market, she will lower her reservation wage which would, in turn, lead to lower pay. This prediction is tested using a data set of graduating college seniors. Results show that women had lower starting-pay expectations, even for men and women with the same major, job-market information, and job-search strategies. Lower pay expectations led to lower pay outcomes for women. However, women who engaged more intensively in career planning had pay expectations and starting pay more in line with those of men.
The impact of IT investment on income and wealth inequality in the postwar US economy

Abstract Inequality in the distribution of family income, which had remained virtually unchanged since the end of World War II until 1968, has increased sharply since then. Inequality in household wealth has increased even more dramatically, with the share of the top 1% doubling since 1976. Perhaps, the most notable technological change over the past 30 years has been the widespread diffusion of computers in the United States. However, when we consider the aggregate time-series regression results, we find that the largest effects on income inequality come from equipment investment and unionization. OCA investment is also found to have a positive and significant effect on income inequality, though not as strong as equipment investment. On the other hand, TFP and labour productivity growth, as well as R&D investment, have no statistical effect on income inequality. Unionization has a decidedly negative effect on income inequality. With regard to wealth inequality, the only two significant effects come from the ratio of the S&P 500 stock index to median house, which has a very strong positive relation, and the minimum wage in constant dollars, which has a negative and less strong relation. None of the other variables is statistically significant. However, investment in OCA per worker has a very strong positive relation to movements in stock prices, which suggests that it is indirectly linked to changes in wealth inequality.
Economic Consequences of Unfunded Vested Pension Benefits

Abstract This paper examines the relationship between unfunded vested pension liabilities and the market value of a firm's shares. This relationship has important implications for the mechanism by which private pensions influence aggregate savings. Attention is paid to modeling the institutional determinants of this relation implied by the ERISA legislation. These considerations require a nonlinear regression model with very special properties that are developed and discussed. Estimation results suggest that ERISA has had an important effect on the relation between unfunded benefits and firm value that previous investigations have neglected.
RNF43 is frequently mutated in colorectal and endometrial cancers

We report somatic mutations of RNF43 in over 18% of colorectal adenocarcinomas and endometrial carcinomas. RNF43 encodes an E3 ubiquitin ligase that negatively regulates Wnt signaling. Truncating mutations of RNF43 are more prevalent in microsatellite-unstable tumors and show mutual exclusivity with inactivating APC mutations in colorectal adenocarcinomas. These results indicate that RNF43 is one of the most commonly mutated genes in colorectal and endometrial cancers.
Exploring Mass Loss, Low-Z Accretion, and Convective Overshoot in Solar Models to Mitigate the Solar Abundance Problem

Solar models using the new lower abundances of Asplund et al. or Caffau et al. do not agree as well with helioseismic inferences as models that use the higher Grevesse & Noels or Grevesse & Sauval abundances. Adopting the new abundances leads to models with sound-speed discrepancies of up to 1.4% below the base of the convection zone (CZ) compared to discrepancies of less than 0.4% with the old abundances; a CZ that is too shallow; and a CZ helium abundance that is too low. Here we briefly review recent attempts to restore agreement, and we evaluate three changes to the models: early mass loss, accretion of low-Z material, and convective overshoot. One goal of these attempts is to explore models that could preserve the structure in the interior obtained with the old abundances while accommodating the new abundances at the surface. Although the mass-losing and accretion models show some improvement in agreement with seismic constraints, a satisfactory resolution to the solar abundance problem remains to be found. In addition, we perform a preliminary analysis of models with the Caffau et al. abundances that shows that the sound-speed discrepancy is reduced to only about 0.6% at the CZ base, compared to 1.4% for the Asplund et al. abundances and 0.4% for the Grevesse & Noels abundances. Furthermore, including mass loss in models with the Caffau et al. abundances may improve sound-speed agreement and help resolve the solar lithium problem.
Homogeneously-catalyzed syntheses in supercritical fluids

Supercritical fluids (SCFs) differ from liquid solvents in a number of important properties, any of which could potentially alter the performance of a chemical reaction performed in a supercritical medium. Although rate, yield and selectivity improvements as well as environmental, health and engineering benefits are all possible, little research has been reported on homogeneously-catalyzed syntheses in SCFs. Several notable successes plus new techniques for solubilizing hydrophilic reagents in SCFs are encouraging further research in this growing field.
Elastic scattering of 1 GeV protons from nuclei

We obtain expressions for proton-nucleus elastic scattering amplitudes in the Glauber approximation which include the effects of spin dependence and Coulomb interactions. These effects are shown to be important for determining the neutron and matter radii for all target nuclei. The results for neutron radii are compared with theoretical predictions.
Pediatric exercise testing

Abstract Exercise testing is a complicated discipline. It requires a thorough understanding of human physiology, multiple protocols, and a wide variety of equipment. As subsequent articles will demonstrate, when this understanding has been achieved, exercise physiology can contribute significantly to the management of many cardiovascular problems of children and adolescents.
Decision trees for entity identification: Approximation algorithms and hardness results

We consider the problem of constructing decision trees for entity identification from a given relational table. The input is a table containing information about a set of entities over a fixed set of attributes and a probability distribution over the set of entities that specifies the likelihood of the occurrence of each entity. The goal is to construct a decision tree that identifies each entity unambiguously by testing the attribute values such that the average number of tests is minimized. This classical problem finds such diverse applications as efficient fault detection, species identification in biology, and efficient diagnosis in the field of medicine. Prior work mainly deals with the special case where the input table is binary and the probability distribution over the set of entities is uniform. We study the general problem involving arbitrary input tables and arbitrary probability distributions over the set of entities. We consider a natural greedy algorithm and prove an approximation guarantee of O(rK ⋅ log N), where N is the number of entities and K is the maximum number of distinct values of an attribute. The value rK is a suitably defined Ramsey number, which is at most log K. We show that it is NP-hard to approximate the problem within a factor of Ω(log N), even for binary tables (i.e., K=2). Thus, for the case of binary tables, our approximation algorithm is optimal up to constant factors (since r2=2). In addition, our analysis indicates a possible way of resolving a Ramsey-theoretic conjecture by Erdos.