cssi/SciSciGPT-SciSciNet huggingface dataset:
The Existence of Homogeneous Groups of Large Ions

Non-existence of groups.---Certain observers have found evidence indicating that the large ions produced by spraying water constitute several distinct groups each having a definite mobility. Using an apparatus similar to theirs, the author fails to confirm this result but finds that the ions distribute themselves continuously over a wide range with all intermediate mobilities present. In other words, he finds a continuous spectrum of mobilities and not a band spectrum. Conclusive proof of this has been obtained by a series of mobility determinations made with a Zeleney tube having a "resolving power" twenty times as large as that of the apparatus mentioned above.Age and mean mobility.---The mean mobility of the ions decreases with time after formation at a rate indicating that the rate of condensation of water vapor on any ion is constant and independent of its size.Growth of ions dependent upon the humidity of the air.---Having replaced the water sprayer by a red-hot platinum wire as a source of ionization, it was possible to control the water vapor density. Drying the air causes a decrease in the rate of growth of the ions.Growth of ions probably due to condensation of water vapor.---The experimental facts are explained by assuming that large ions grow by condensation of water vapor on a nucleus. This assumption is consistent with the views as to the nature of the large ion held by Barus, Aitken, Thompson, and others.
Nutritional Status of Female Athletes with Subclinical Eating Disorders

Abstract Objective To assess the energy and nutritional status of female athletes with subclinical eating disorders and compare them with that of control subjects and standard norms. Design Group classification (subclinical eating disorder or control) was based on responses to a health and diet history questionnaire, a battery of self-report eating disorder questionnaires, and an in-depth interview. Energy and nutrient intakes and energy expenditure were determined by means of 7-day weighed food records and 7-day activity logs. Micronutrient status was assessed for iron, zinc, magnesium, vitamin B-12, and folate. Subjects Twenty-four female athletes with subclinical eating disorders and 24 female control athletes. Statistical analyses Descriptive statistics were used to analyze demographic data. One-way analysis of variance was used to determine group differences in energy and nutrient intakes, energy balance, and blood values. Results Groups were similar in age, height, weight, fat-free mass, and body mass index. Mean energy intake was lower in the group with subclinical eating disorders (1,989kcal/day) than in the control group (2,300kcal/day; P =.004), whereas mean energy expenditures were similar (2,405 and 2,293kcal/day, respectively). The group with subclinical eating disorders had significantly ( P Conclusion Although female athletes with subclinical eating disorders had dietary intakes of energy, protein, carbohydrate, and certain micronutrients that were below recommended levels, micronutrient status appeared relatively unaffected, probably due to their use of supplements. J Am Diet Assoc. 1998;98:419-425 .
Absorption by branes and Schwinger terms in the world volume theory

Abstract We study how coincident Dirichlet 3-branes absorb incident gravitons polarized along their world volume. We show that the absorption cross-section is determined by the central term in the correlator of two stress-energy tensors. The existence of a non-renormalization theorem for this central charge in four-dimensional N = 4 supersymmetric Yang-Mills theories shows that the leading term at low energies in the absorption cross-section is not renormalized. This guarantees that the agreement of the cross-section with semiclassical supergravity, found in earlier work, survives all loop corrections. The connection between absorption of gravitons polarized along the brane and Schwinger terms in the stress-energy correlators of the world volume theory holds in general. We explore this connection to deduce some properties of the stress-energy tensor OPE's for 2-branes and 5-branes in 11 dimensions, as well as for 5-branes in 10 dimensions.
MECHANISMS OF HUMAN KIDNEY STONE FORMATION

The precise mechanisms of kidney stone formation and growth are not completely known, even though human stone disease appears to be one of the oldest diseases known to medicine. With the advent of the new digital endoscope and detailed renal physiological studies performed on well phenotyped stone formers, substantial advances have been made in our knowledge of the pathogenesis of the most common type of stone former, the idiopathic calcium oxalate stone former as well as nine other stone forming groups. The observations from our group on human stone formers and those of others on model systems have suggested four entirely different pathways for kidney stone formation. Calcium oxalate stone growth over sites of Randall's plaque appear to be the primary mode of stone formation for those patients with hypercalciuria. Overgrowths off the ends of Bellini duct plugs have been noted in most stone phenotypes, do they result in a clinical stone? Micro-lith formation does occur within the lumens of dilated inner medullary collecting ducts of cystinuric stone formers and appear to be confined to this space. Lastly, cystinuric stone formers also have numerous small, oval, smooth yellow appearing calyceal stones suggestive of formation in free solution. The scientific basis for each of these four modes of stone formation are reviewed and used to explore novel research opportunities.
Flagellar Kinematics and Swimming of Algal Cells in Viscoelastic Fluids

The motility of microorganisms is influenced greatly by their hydrodynamic interactions with the fluidic environment they inhabit. We show by direct experimental observation of the bi-flagellated alga Chlamydomonas reinhardtii that fluid elasticity and viscosity strongly influence the beating pattern - the gait - and thereby control the propulsion speed. The beating frequency and the wave speed characterizing the cyclical bending are both enhanced by fluid elasticity. Despite these enhancements, the net swimming speed of the alga is hindered for fluids that are sufficiently elastic. The origin of this complex response lies in the interplay between the elasticity-induced changes in the spatial and temporal aspects of the flagellar cycle and the buildup and subsequent relaxation of elastic stresses during the power and recovery strokes.
Stereochemical consequences of the Lewis acid-promoted 3-aza-Cope rearrangement of N-alkyl-N-allyl enamines

Abstract Internal and relative asymmetric induction were examined for the electrophile promoted 3-aza-Cope rearrangement of substituted N -alkyl- N -allyl enamines. In general, internal asymmetric induction was highly variable, and was dependent both upon the nature of the electrophilic reagent and substrate. However, substitution at C-4 of the substrate served to anchor the transition state of the substrates, and product selectivity was typically > 95:5. When the N -alkyl substituent was tethered to C-4, ring expansion from a five- to a nine-membered ring was obtained. The key features necessary for the stereoselective [3,3] rearrangement of N -alkyl- N -allyl enamies were determined through these studies. In the absence of a substituent at C-4, internal asymmetric induction that resulted from chair:boat transition state selectivity was highly variable, and was dependent both on the nature of the electrophilic reagent and substrate. In general, poor selectivity was obtained in these studies, and placement of a chiral peripheral substituent on the nitrogen did not improve selectivity through relative asymmetric induction. Substitution at C-4 was critical to the stereoselective rearrangement of these substrates, and incorporation of a methyl group at C-4 served to anchor the transition state of the acyclic substrates in the chair conformation. In these examples, chair:boat selectivity was typically > 95:5, and resulted in selective product formation. Rearrangement of a cyclic substrate, tethered at the C-4 and nitrogen positions, also generated products with a high degree of control over transition state geometry. Based on these studies, the scope and limitations of the charge accelerated [3,3] rearrangement of N -alkyl- N -allyl enamies has been outlined for future use.
Ultrafast control of electron spin in a quantum dot using geometric phase

Abstract We propose a scheme to perform arbitrary unitary operations on a single electron–spin qubit in a quantum dot. The design is solely based on the geometrical phase that the qubit state acquires after a cyclic evolution in the parameter space. The scheme is utilizing ultrafast linearly-chirped pulses providing adiabatic excitation of the qubit states and the geometric phase is fully controlled by the relative phase between pulses. The analytic expression of the evolution operator for the electron spin in a quantum dot, which provides a clear geometrical interpretation of the qubit dynamics is obtained. Using parameters of InGaN/GaN, GaN/AlN quantum dots we provide an estimate for the time scale of the qubit rotations and parameters of the external fields.
Work incentives and the Food Stamp Program

Abstract Labor supply theory makes strong predictions about how the introduction or expansion of a social welfare program impacts work effort. Although there is a large literature on the work incentive effects of AFDC and the EITC, relatively little is known about the work incentive effects of the Food Stamp Program and none of the existing literature is based on quasi-experimental methods. We use the cross-county introduction of the program in the 1960s and 1970s to estimate the impact of the program on the extensive and intensive margins of labor supply, earnings, and family cash income. Consistent with theory, we find reductions in employment and hours worked when food stamps are introduced. The reductions are concentrated among families headed by single woman.
Are perseverance and self‐efficacy costless? Assessing entrepreneurs' regretful thinking

New business formation is a formidable and daunting task, which may require personal perseverance and self-efficacy. If this is indeed the case, will entrepreneurs and non-entrepreneurs differ on such attributes? Also, if high levels of perseverance and self-efficacy help entrepreneurs to overcome setbacks, snags, and obstacles, do these positive attributes co-occur with significant personal costs, such as the tendency to experience regretful thinking? This study uses a random sample of 217 patent inventors in the medical industry (surgery devices) to address these questions. Results indicate that entrepreneurs score significantly higher on self-efficacy and on two distinct aspects of perseverance—perceived control over adversity and perceived responsibility regarding outcome of adversity—than did non-entrepreneurs. Also, although entrepreneurs report the same number of regrets, their regrets are stronger and are qualitatively different from those reported by non-entrepreneurs. These findings suggest that perseverance and self-efficacy do indeed co-occur with regretful thinking. Finally, post hoc analysis reveals that the higher the overall perseverance scores of patent inventors, the higher their annual earnings. We conclude by examining the implications for theory, researcher, and practice. Copyright © 2005 John Wiley & Sons, Ltd.
Provable programs and processors

"A proof of correctness guarantees that a program will run correctly every time it is executed." That statement is not necessarily true. Suppose, for sake of concreteness, that a valid proof of a Fortran program has been constructed. When this program was proved, it most likely was proved in isolation from the other software components which ultimately will be involved in actually making the program run. So, even though we have proved the Fortran program, one of these other components, or the system hardware, may malfunction causing the actual machine language program that is executed to produce an error. These comments are not an argument against proving programs at the Fortran level, but rather an indication of the eventual need for a completely proved computing system.
Spin-induced Disk Precession in the Supermassive Black Hole at the Galactic Center

Sagittarius A* is a compact radio source at the Galactic center that is thought to be the radiative manifestation of a 2.6 × 106 M☉ supermassive black hole. At least a portion of its spectrum—notably the millimeter/submillimeter "bump"—appears to be produced within the inner portion (r < 10rS) of a hot, magnetized Keplerian flow, whose characteristics are also consistent with the ~10% linear polarization detected from this source at millimeter wavelengths. (The Schwarzschild radius, rS, for an object of this mass M is 2GM/c2 ≈ 7.7 × 1011 cm, or roughly 1/20 AU.) The recent detection of a 106 day cycle in Sgr A*'s radio variability adds significant intrigue to this picture since it may signal a precession of the disk induced by the spin a of the black hole. The dynamical timescale near the marginally stable orbit around an object with this mass is ≈20 minutes. Thus, since the physical conditions associated with the disk around Sgr A* imply rigid-body rotation, a precession period of 106 days may be indicative of a small black hole spin if the circularized flow is confined to a region ~30rS, for which a ≈ (M/10)(ro/30rS)5/2. The precession of a larger structure would require a bigger black hole spin. We note that a small value of a/M (<0.1) would be favored if the nonthermal (~1-20 cm) portion of Sgr A*'s spectrum is powered with energy extracted via a Blandford-Znajek type of process, for which the observed luminosity would correspond to an outer disk radius ro ~ 30rS. Such a small disk size is also suggested by earlier hydrodynamical simulations and is implied by Sgr A*'s spectral and polarimetric characteristics.
An analytical framework for siting and sizing biomass fuel plants

Abstract A generalized framework is presented for analyzing the relative attractiveness of biomass fuel production investments on a disaggregate level, using a systems approach to integrate sitespecific considerations. A model based on this approach may be used to site and size prospective biomass fuel plants and to identify and specify critical factors that threaten or enhance the viability of investments. Rather than providing a single mean value for each critical factor, structural relationships have been formulated. Generalized feedstock supply curves, processing cost functions and modal transportation cost functions are formulated to specify feedstock-production and fuel transport sub-systems. This analytical framework may be applied in any area with abundant biomass. Local costs and conditions and fuel demand patterns would be used to calibrate the model for each local area.
Remembering the Good Old Days: The Moderating Role of Consumer Affective State on the Effectiveness of Nostalgic Advertising

Employing different experimental priming procedures and advertising treatments across two studies, we examine the moderating role of consumer affective state on individuals’ responses to nostalgic and nonnostalgic advertising. Consistent with hypothesized expectations, our findings indicate that when consumers are in a positive affective state they respond more favorably (i.e., report more positive memories and favorable brand-related responses) to nostalgic (versus nonnostalgic) ads. In contrast, one's negative affective state appears to play a limited role in affecting responses between ad types. The theoretical implications of these findings as they relate to nostalgic advertising effects are discussed, and recommendations for advertising practitioners are offered.
Approaches to design problems in conversion equipment

The term conversion equipment is used here to denote devices which either express analog quantities in pulse-coded digital form or express pulse-coded digital data in analog form. These devices are called coders and decoders, respectively.
THREE-DIMENSIONAL MAGNETOHYDRODYNAMIC MODELING OF THE SOLAR WIND INCLUDING PICKUP PROTONS AND TURBULENCE TRANSPORT

To study the effects of interstellar pickup protons and turbulence on the structure and dynamics of the solar wind, we have developed a fully three-dimensional magnetohydrodynamic solar wind model that treats interstellar pickup protons as a separate fluid and incorporates the transport of turbulence and turbulent heating. The governing system of equations combines the mean-field equations for the solar wind plasma, magnetic field, and pickup protons and the turbulence transport equations for the turbulent energy, normalized cross-helicity, and correlation length. The model equations account for photoionization of interstellar hydrogen atoms and their charge exchange with solar wind protons, energy transfer from pickup protons to solar wind protons, and plasma heating by turbulent dissipation. Separate mass and energy equations are used for the solar wind and pickup protons, though a single momentum equation is employed under the assumption that the pickup protons are comoving with the solar wind protons. We compute the global structure of the solar wind plasma, magnetic field, and turbulence in the region from 0.3 to 100 AU for a source magnetic dipole on the Sun tilted by 0°-90° and compare our results with Voyager 2 observations. The results computed with and without pickup protons are superposed to evaluate quantitatively the deceleration and heating effects of pickup protons, the overall compression of the magnetic field in the outer heliosphere caused by deceleration, and the weakening of corotating interaction regions by the thermal pressure of pickup protons.
Big bang nucleosynthesis - The standard model and alternatives

Big bang nucleosynthesis provides (with the microwave background radiation) one of the two quantitative experimental tests of the big bang cosmological model. This paper reviews the standard homogeneous-isotropic calculation and shows how it fits the light element abundances ranging from He-4 at 24% by mass through H-2 and He-3 at parts in 10(exp 5) down to Li-7 at parts in 10(exp 10). Furthermore, the recent large electron positron (LEP) (and the stanford linear collider (SLC)) results on the number of neutrinos are discussed as a positive laboratory test of the standard scenario. Discussion is presented on the improved observational data as well as the improved neutron lifetime data. Alternate scenarios of decaying matter or of quark-hadron induced inhomogeneities are discussed. It is shown that when these scenarios are made to fit the observed abundances accurately, the resulting conlusions on the baryonic density relative to the critical density, omega(sub b) remain approximately the same as in the standard homogeneous case, thus, adding to the robustness of the conclusion that omega(sub b) approximately equals 0.06. This latter point is the driving force behind the need for non-baryonic dark matter (assuming omega(sub total) = 1) and the need for dark baryonic matter, since omega(sub visible) is less than omega(sub b).
Catching a bullet: direct evidence for the existence of dark matter

We present X-ray and weak lensing observations of the merging cluster system 1E0657–556. Due to the recently collision of a merging subcluster with the main cluster, the X-ray plasma has been displaced from the cluster galaxies in both components. The weak lensing data shows that the lensing surface potential is in spatial agreement with the galaxies ( ∼ 10 % of the observed baryons) and not with the X-ray plasma ( ∼ 90 % of the observed baryons). We argue that this shows that regardless of the form of the gravitational force law at these large distances and low accelerations, these observations require that the majority of the mass of the system be some form of unseen matter.
Invariant surface alignment in the presence of affine and some nonlinear transformations.

Abstract In this paper, we introduce a non-iterative geometric-based method to align 3D brain surfaces into standard coordinate system, which is based on a novel set of surface landmarks (e.g., inflection and/or zero torsion points residing on parabolic contours), which are intrinsic and are computed from the differential geometry of the surface. This is in contrast to existing methods that depend on anatomical landmarks that require expert intervention to locate – a very hard task. The landmarks are local and are preserved under affine transformations. To reduce the sensitivity of the landmarks to noise, we use a B-Spline surface representation that smoothes out the surface prior to the computation of the landmarks. The alignment is achieved by establishing correspondences between the landmarks after a sorting of the landmarks based on derived absolute invariants (volumes confined between parallelepipeds spanned by sets of the landmark point quadruplets). The method is tested for intra- and inter-brain alignments while entertaining affine, cubic and fourth-order polynomial nonlinear transformations using distance mapping as well as comparison with an expert alignment, and promising results are obtained. When comparing our automatic alignment with that of an expert we arrived at complete agreement for the more difficult case of partial alignment of sectional slab materials of five rats with an atlas (a whole brain of rat). This perfect alignment was only based on the surface structure for our procedure, whereas it was based on the staining and the external and internal structures for the expert.
Catalytic Enantioselective Construction of Quaternary Stereocenters: Assembly of Key Building Blocks for the Synthesis of Biologically Active Molecules

ConspectusThe ever-present demand for drugs with better efficacy and fewer side effects continually motivates scientists to explore the vast chemical space. Traditionally, medicinal chemists have focused much attention on achiral or so-called “flat” molecules. More recently, attention has shifted toward molecules with stereogenic centers since their three-dimensional structures represent a much larger fraction of the chemical space and have a number of superior properties compared with flat aromatic compounds. Quaternary stereocenters, in particular, add greatly to the three-dimensionality and novelty of the molecule. Nevertheless, synthetic challenges in building quaternary stereocenters have largely prevented their implementation in drug discovery. The lack of effective and broadly general methods for enantioselective formation of quaternary stereocenters in simple molecular scaffolds has prompted us to investigate new chemistry and develop innovative tools and solutions.In this Account, we describe thr...
Disparity in wages but not in returns to capital between rich and poor countries

Abstract One of the striking features of the international economy is that while the level of average wage rates in rich countries is many times that in pour countries, their average rates of return to capital seem to be roughly similar or the differences in them relatively very small. This cannot be fully explained away by the fact that capital is internationally much more mobile than labor. There is remarkably little movement of return-sensitive private capital between the richest and the poorest countries. In this paper we assume instead that factors of production are internationally immobile, and try to explain the observed asymmetry in the pattern of factor prices in terms of particular types of differences in production functions between rich and poor countries, in terms of differential learning effects and differential degrees of specialization in the sector producing intermediate inputs and services.
Special transformations in algebraically closed valued fields

Abstract We present two of the three major steps in the construction of motivic integration, that is, a homomorphism between Grothendieck semigroups that are associated with a first-order theory of algebraically closed valued fields, in the fundamental work of Hrushovski and Kazhdan (2006) [8] . We limit our attention to a simple major subclass of V -minimal theories of the form ACV F S ( 0 , 0 ) , that is, the theory of algebraically closed valued fields of pure characteristic 0 expanded by a ( V F , Γ ) -generated substructure S in the language L RV . The main advantage of this subclass is the presence of syntax. It enables us to simplify the arguments with many different technical details while following the major steps of the Hrushovski–Kazhdan theory.
Rapid control of previously untreated multiple myeloma with bortezomib–lenalidomide–dexamethasone (BLD)

Between April 2006 and June 2009, 34 newly diagnosed patients with multiple myeloma received one to three courses of bortezomib 1.3 mg/m(2) i.v. four times, lenalidomide 25 mg p.o. daily for 21 days and dexamethasone 20 mg/m(2) p.o. for 4 days beginning on days 1, 9 and 17 (BLD). There was rapid onset of remission in 30 patients (88%) similar to the frequency of 87% induced by a previous combination of bortezomib-thalidomide-dexamethasone (BTD). After a median of 3.6 months, 28 patients received intensive therapy with high-dose melphalan supported by autologous blood stem cells, so that the overall frequency of complete remission (CR) was 44%, similar to the frequency of 37% observed previously. Side effects due to thalidomide with previous BTD were less frequent and severe with BLD. The combination of BLD given for one or two courses was an effective primary treatment for newly diagnosed patients with multiple myeloma.
Tightness of the recentered maximum of log-correlated Gaussian fields

We consider a family of centered Gaussian fields on the d-dimensional unit box, whose covariance decreases logarithmically in the distance between points. We prove tightness of the recentered maximum of the Gaussian fields and provide exponentially decaying bounds on the right and left tails. We then apply this result to a version of the two-dimensional continuous Gaussian free field.
Chemistry at the interior atoms of polycyclic aromatic hydrocarbons

For more than 150 years, chemical reactions that make new covalent bonds to polycyclic aromatic hydrocarbons (PAHs) have been confined almost exclusively to substitution and addition reactions on the perimeters of the compounds (“edge chemistry”). The “interior” atoms of PAHs, those belonging to three rings, almost never engage in new σ-bond-forming reactions. A compound with no edges, C60, was the first polycyclic carbon π-system observed to exhibit such reactivity. More recently, smaller subunits of C60, which we call geodesic polyarenes, have also been found to exhibit “fullerene-type chemistry” at their interior carbon atoms. These reactions are all reviewed together here for the first time. The review ends with speculation that σ-bond-forming reactions may also be observed someday even in certain planar, benzenoid PAHs, although no examples have yet been reported.
Preparation and characterization of active niobium, tantalum and tungsten metathesis catalysts

Abstract Octahedral complexes of the type trans , mer - and cis , mer -M(CHCMe 3 )-(L) 2 X 3 (M = Nb or Ta, L = a tertiary phosphine, X = Cl or Br) react with terminal olefins to give only organic products arising from rearrangement of an intermediate metallacyclobutane complex, and olefin complexes (olefin = ethylene, propylene, styrene) of the type trans , mer -Ta(olefin)(L) 2 X 3 . Replacing two of the halides with t-butoxide ligands yields complexes of the type M(CHCMe 3 )(OCMe 3 ) 2 (L)Cl which are active metathesis catalysts for cis -2-pentene. We have extended the principles of Group V chemistry to tungsten by transferring a neopentylidene ligand from Ta(CHCMe 3 )(PEt 3 ) 2 -Cl 3 to W(O)(OCMe 3 ) 4 to give W(O)(CHCMe 3 )(PEt 3 ) 2 Cl 2 in high yield. It reacts slowly with ethylene, butene, and styrene to give tertiarybutylethylene and analogous complexes of the type W(O)(CHR)(PEt 3 ) 2 Cl 2 (R = H, Pr, Ph). In the presence of a trace of AlCl 3 these reactions are rapid at 25 °C and the solutions are active for metathesis of 1-butene and cis -2-pentene. We have also developed a test for metathesis of 1-butene which tells us what are some of the reactions of intermediate metallacyclobutane and alkylidene complexes which terminate the metathesis chain reaction.
Reconciling Political and Economic Goals in the Net Neutrality Debate

The net neutrality debate is one of several sites of struggles to adapt and redefine rights and obligations of stakeholders in the Internet-centric communications system. Its outcomes will shape the future of the Internet and influence the level and distribution of its benefits. We identify key values that drive the net neutrality discussion and examine the governance mechanisms proposed to achieve these objectives. We find that there is no single policy instrument that allows realization of the range of valued political and economic objectives simultaneously. Contrary to some of the claims advanced in the current debate, safeguarding multiple goals requires a combination of instruments that will likely involve government and nongovernment measures. Furthermore, promoting goals such as the freedom of speech, political participation, investment, and innovation calls for complementary policies.
A DIAGRAMMATIC ALEXANDER INVARIANT OF TANGLES

We give a new construction of the one-variable Alexander polynomial of an oriented knot or link, and show that it generalizes to a vector valued invariant of oriented tangles.
The militarization of local law enforcement: is race a factor?

Recent events have placed a spotlight on the increasing militarization of local law enforcement. While ample anecdotal evidence suggests a link between race and the militarization of police, empirical analysis has yet to be performed. In this study, I find that, conditional on crime rate, the presence of a large African-American population is negatively correlated to police acquisition of mine-resistant ambush protected (MRAP) vehicles. Conversely, greater residential segregation is positively correlated to MRAP procurement. This result highlights the problem with growing segregation, in suburbs as well as urban centres, in the United States.
Tumor angiogenesis as a predictive marker for organ preservation in patients with advanced laryngeal carcinoma.

Background The purpose of this study was to retrospectively investigate tumor angiogenesis as a predictive marker for response to neoadjuvant chemotherapy, organ preservation, and survival in patients with advanced laryngeal carcinoma. Methods A total of 332 patients with stage III (188 patients) or stage IV (144 patients) squamous cell carcinoma of the larynx were entered in the prospective trial conducted by the Department of Veteran Affairs Laryngeal Cancer Study Group. Of this patient population, 20 pretreatment biopsy specimens were available from the chemotherapy arm for immunohistochemical analysis of Factor VIII expression. Two blinded investigators determined microvessel density in each patient by manual inspection of 10 high-power (400×) fields (HPF). Results The patients who had a partial response (>50% decrease in tumor volume) or complete response to chemotherapy had a mean value of 20.90 (± 8.09 standard deviation [SD]) blood vessels per HPF. Those who did not respond to chemotherapy and thus required a total laryngectomy had a mean value of 32.99 (± 10.10 SD) vessels per HPF. The difference of the means was statistically significant using a two-tailed t test (P <.0085). Kaplan-Meier survival curve analysis also revealed that patients with vessel counts above the mean tended to have poorer survival than those below the mean regardless of treatment selection. The most-vascular tumors, those greater than 1 SD above the mean, had a statistically significant difference in survival and laryngeal preservation (P = .0345). Conclusions These results indicate that tumor angiogenesis, as measured by number of vessels per HPF, was associated with decreased responsiveness to chemotherapy and radiation for larynx preservation. The most-vascular tumors also were associated with poorer survival than those with lesser degrees of angiogenesis.
Efficient and robust constitutive integrators for single-crystal plasticity modeling

Abstract Small-scale deformation phenomena such as subgrain formation, development of texture, and grain boundary sliding require simulations with a high degree of spatial resolution. When we consider finite-element simulation of metal deformation, this equates to thousands or hundreds of thousands of finite elements. Simulations of the dynamic deformations of metal samples require elastic–plastic constitutive updates of the material behavior to be performed over a small time step between updates, as dictated by the Courant condition. Further, numerical integration of physically-based equations is inherently sensitive to the step in time taken; they return different predictions as the time step is reduced, eventually approaching a stationary solution. Depending on the deformation conditions, this converged time step becomes short (10 −9 s or less). If an implicit constitutive update is applied to this class of simulation, the benefit of the implicit update (i.e., the ability to evaluate over a relatively large time step) is negated, and the integration is prohibitively slow. The present work recasts an implicit update algorithm into an explicit form, for which each update step is five to six times faster, and the compute time required for a plastic update approaches that needed for a fully-elastic update. For dynamic loading conditions, the explicit model is found to perform an entire simulation up to 50 times faster than the implicit model. The performance of the explicit model is enhanced by adding a subcycling algorithm to the explicit model, by which the maximum time step between constitutive updates is increased an order of magnitude. These model improvements do not significantly change the predictions of the model from the implicit form, and provide overall computation times significantly faster than the implicit form over finite-element meshes. These modifications are also applied to polycrystals via Taylor averaging, where we also see improved model performance.
Optical and structural characterization of InAs/GaAs quantum wells

Three InAs/GaAs single quantum wells of two-, three-, and four-monolayer thickness were characterized using optical and structural techniques. The results of high-resolution transmission electron (HRTEM) microscopy and optical studies which combine absorption, photoluminescence (PL), photoreflectance, and cathodoluminescence are presented. Using the polarization modulated absorptance technique, we observed two absorption features in our samples at 77 K. On the basis of their polarization properties and comparison with an envelope function calculation, these structures are assigned to transitions between the confined heavy-hole and confined and unconfined electron levels. Photoreflectance spectra of the three-monolayer sample in 77-300 K range show only the fundamental quantum well transition. The temperature dependence of this transition is approximately linear with a slope of 2.2 x 10 exp -4 eV/K, which is significantly lower than in both constituent materials. Comparison to the absorption data reveals that the PL spectra are affected by the carrier diffusion and therefore do not provide direct measure of the exciton density of states. The HRTEM images indicate that, while the interfaces of the two-monolayer sample are smooth and the well thickness is uniform, the four-monolayer sample has uneven interfaces and contains domains of two, three, and four monolayers.
Ordered structures and metastable alloys grown by OMVPE

Our understanding of the thermodynamics of mixing in semiconductor solids has evolved from the purely empirical regular solution model to models based on the electron energy states in the solid, including the delta-lattice parameter (DLP) model and, more recently, first principles calculations. These models are in agreement that the enthalpy of mixing is invariably ⩾ 0 for III/V and II/VI alloys, and increases with increasing difference in lattice constant for the constituent binary compounds. In terms of the simple thermochemical mixing models, this suggests the occurrence of miscibility gaps. Solid phase immiscibility has indeed been observed in a number of systems. Nevertheless, such alloys can be grown by OMVPE, including the highly metastable alloys GaPSb and InPSb. Initially surprising was the occurrence of ordered structures in these same alloys. The regular solution model apparently specifically excludes immiscibility and ordering in the same system. However, when the positive enthalpy of mixing is due to strain energy effects, as in III/V and II/VI alloys, Hume-Rothery recognized very early that such phenomena should be anticipated. This was later confirmed by the detailed first principles calculations. In fact, the tendency for ordering is anticipated to increase as the difference in tetrahedral radii of the elements sharing a common sublattice increases. Ordered structures have now been observed in several III/V alloy systems including the ternary systems GaAsSb, GaInP, AllnAs, AlGaAs, and GaInAs, and the quarternaries GaInAsP, GaInAsSb, and AlGaInP. In this paper, ordering in other alloy systems such as GaPSb, InPSb, InAsSb, and GaAsP will be described. An unexpected observation is that the preferred ordered structure for the ternaries GaInP, GaPSb, InPSb, InAsSb, and GaAsP involves ordering along the <111 directions, forming the Cu-Pt (L11) structure. This is also true of GaAsSb grown by MBE. Both the first principles calculations and simple strain energy calculations indicate that such ordered structures are more stable than the disordered solid solution, but less stable than other ordered structures. The chalcopyrite structure (E10), with ordering along <210 directions, and the Cu-Au structure (L10), where ordering occurs along the <100 directions, are considerably more stable. The occurrence of these structures must be explained in terms of the relative strain energies of the various ordered structures at the surface and/or kinetic processes occurring during epitaxial growth. The importance of kinetic effects is indicated by the importance of growth parameters such as growth rate, temperature, and substrate orientation in determining both the degree of ordering and the specific ordered structures observed.
Data mining a small molecule drug screening representative subset from NIH PubChem.

PubChem is a scientific showcase of the NIH Roadmap Initiatives. It is a compound repository created to facilitate information exchange and data sharing among the NIH Roadmap-funded Molecular Library Screening Center Network (MLSCN) and the scientific community. However, PubChem has more than 10 million records of compound information. It will be challenging to conduct a drug screening of the whole database of millions of compounds. Thus, the purpose of the present study was to develop a data mining cheminformatics approach in order to construct a representative and structure-diverse sublibrary from the large PubChem database. In this study, a new chemical diverse representative subset, rePubChem, was selected by whole-molecule chemistry-space matrix calculation using the cell-based partition algorithm. The representative subset was generated and was then subjected to evaluations by compound property analyses based on 1D and 2D molecular descriptors. The new subset was also examined and assessed for self-...
A generalization of Filliman duality

Filliman duality expresses (the characteristic measure of) a convex polytope P containing the origin as an alternating sum of simplices that share supporting hyperplanes with P. The terms in the alternating sum are given by a triangulation of the polar body P^o. The duality can lead to useful formulas for the volume of P. A limiting case called Lawrence's algorithm can be used to compute the Fourier transform of P. In this note we extend Filliman duality to an involution on the space of polytopal measures on a finite-dimensional vector space, excluding polytopes that have a supporting hyperplane coplanar with the origin. As a special case, if P is a convex polytope containing the origin, any realization of P^o as a linear combination of simplices leads to a dual realization of P.
Viscous Flow in a Controlled Diffusion Compressor Cascade With Increasing Incidence

A detailed two-component laser Doppler velocimeter mapping of the flow through a controlled diffusion compressor cascade at low Mach number (∼ 0.25) and Reynolds number of about 7×10 5 , at three inlet air angles from design to near stall, is reported. Results for pressure-side boundary layer and near-wake also are summarized. Information sufficient to allow preliminary assessment of viscous codes is tabulated
Electroweak corrections in technicolor reconsidered

Abstract Radiative corrections to electroweak parameters in technicolor theories may be evaluated by one of two techniques: either one estimates spectral function integrals using scaled QCD data, or one uses naive dimensional analysis with a chiral lagrangian. The former yields corrections to electroweak parameters proportional to the number of flavors and the number of colors, while the latter is proportional to the number of flavors squared and is independent of the number of colors. We attempt to resolve this apparent contradiction by showing that the spectrum of technicolor one obtains by scaling QCD data to high energies is unlikely to resemble that of an actual technicolor theory. The resonances are likely to be much lighter than naively supposed and the radiative corrections to electroweak parameters may by much larger. We also argue that much less is known about the spectrum and the radiative corrections in technicolor than was previously believed.
Metallicity and Alpha-Element Abundance Measurement in Red Giant Stars from Medium-Resolution Spectra

We present a technique that applies spectral synthesis to medium-resolution spectroscopy (MRS; -->R ~ 6000) in the red ( -->6300 A [ Fe/H ] = − 0.8). A star-by-star comparison of HRS versus MRS [α/Fe] estimates indicates that the precision in -->[ α/Fe ]MRS is 0.05 dex. The errors in -->[ Fe/H ]MRS and -->[ α/Fe ]MRS increase beyond 0.25 dex only below signal-to-noise ratios of 20 A−1, which is typical for existing MRS of the red giant stars in Leo I, one of the most distant Milky Way satellites (250 kpc).
Beam-return current systems in solar flares

The importance of electron beams in solar flare dynamics is well known. In order to understand the dynamics produced by beams it is essential to have a clear understanding of the role beam driven return currents play and whether electrostatic or inductive electric fields maintain the return current. We show that inductive electric fields are responsible for driving return currents under solar conditions.
The Szegö condition for Coulomb Jacobi matrices

A Jacobi matrix with an → 1, bn → 0 and spectral measure v'(x)dx + dvsing(x) satisfies the Szego condition if ∫0π ln[v'(2cosθ)]dθ is finite. We prove that if an ≡ 1 + /α n + O(n-1-e), bn ≡ /βn; + O(n-1-e) with 2α ≥ |β|and e > 0, then the corresponding matrix is Szego.
On-demand power management for ad hoc networks

Abstract Battery power is an important resource in ad hoc networks. It has been observed that in ad hoc networks, energy consumption does not reflect the communication activities in the network. Many existing energy conservation protocols based on electing a routing backbone for global connectivity are oblivious to traffic characteristics. In this paper, we propose an extensible on-demand power management framework for ad hoc networks that adapts to traffic load. Nodes maintain soft-state timers that determine power management transitions. By monitoring routing control messages and data transmission, these timers are set and refreshed on-demand. Nodes that are not involved in data delivery may go to sleep as supported by the MAC protocol. This soft state is aggregated across multiple flows and its maintenance requires no additional out-of-band messages. We implement a prototype of our framework in the ns-2 simulator that uses the IEEE 802.11 MAC protocol. Simulation studies using our scheme with the Dynamic Source Routing protocol show a reduction in energy consumption near 50% when compared to a network without power management under both long-lived CBR traffic and on–off traffic loads, with comparable throughput and latency. Preliminary results also show that it outperforms existing routing backbone election approaches.
q-Partition algebra combinatorics

We study a q-analog Q"r(n,q) of the partition algebra P"r(n). The algebra Q"r(n,q) arises as the centralizer algebra of the finite general linear group GL"n(F"q) acting on a vector space IR"q^r coming from r-iterations of Harish-Chandra restriction and induction. For n>=2r, we show that Q"r(n,q) has the same semisimple matrix structure as P"r(n). We compute the dimension d"n","r(q)=dim(IR"q^r) to be a q-polynomial that specializes as d"n","r(1)=n^r and d"n","r(0)=B(r), the rth Bell number. Our method is to write d"n","r(q) as a sum over integer sequences which are q-weighted by inverse major index. We then find a basis of IR"q^r indexed by n-restricted q-set partitions of {1,...,r} and show that there are d"n","r(q) of these.
Pumapaint project summary : Final notes

The PumaPaint project is a web robot that allows users to create original artwork on the World Wide Web. The site allows control ofa PUMA 760 robot equipped with four paintbrushes, jars ofred, green, blue and yellow paint and white paper attached to a vertical easel. Users must download a java TM interface allowing interactive control ofthe robot. This interface contains two windows showing live camera views ofthe work site and various controlsfor connecting and disconnecting to the robot, viewing the task status and controlling the painting task. The site operatedfrom June 1998 until March, 2000. This paper discusses the author 's experiences in operating the site throughout its lfecycle and discusses future plans for the PumaPaint project.
Design of Highly Stable Optical Support Structure

As spaceborne optical systems increase in diameter to achieve improved resolution, the stability requirements imposed on structures approach values which were unthinkable only several years ago. To achieve the capabilities of these apertures optical path errors must not exceed a specific fraction of the wavelength of light, and this fraction, typically x/20 rms in the focal plane, is independent of system size. Thus, from a percentage error basis, large optical support structures represent a far more formidable development task than do smaller systems. The Large Space Telescope (LST) sponsored by MSFC/NASA is a case in point. The Optical Telescope Assembly (OTA) is shown (Fig. 1) installed in the LST spacecraft. The vertex-to-vertex spacing of the primary and secondary mirror is 193 inches. To achieve satisfactory optical performance, this spacing must be maintained constant to a precision of -Â±11.1 for observation periods up to 10 hours. During this time it may be necessary to alter the spacecraft attitude with respect to the sun, which would change the temperature levels and gradients within the structures. It is believed that by exploiting the use of graphite-epoxy in a novel manner, the stringent alignment require-ments can be satisfied with a nominally passive structure.