cssi/SciSciGPT-SciSciNet huggingface dataset:
Fusion reactor systems

In this review we consider deuterium-tritium (D-T) fusion reactors based on four different plasma-confinement and heating approaches: the tokamak, the theta-pinch, the magnetic-mirror, and the laser-pellet system. We begin with a discussion of the dynamics of reacting plasmas and basic considerations of reactor power balance. The essential plasma physical aspects of each system are summarized, and the main characteristics of the corresponding conceptual power plants are described. In tokamak reactors the plasma densities are about ${10}^{20}$ ${\mathrm{m}}^{\ensuremath{-}3}$, and the $\ensuremath{\beta}$ values (ratio of plasma pressure to confining magnetic pressure) are approximately 5%. Plasma burning times are of the order of 100-1000 sec. Large superconducting dc magnets furnish the toroidal magnetic field, and 2-m thick blankets and shields prevent heat deposition in the superconductor. Radially diffusing plasma is diverted away from the first wall by means of null singularities in the poloidal (or transverse) component of the confining magnetic field. The toroidal theta-pinch reactor has a much smaller minor diameter and a much larger major diameter, and operates on a 10-sec cycle with 0.1-sec burning pulses. It utilizes shock heating from high-voltage sources and adabatic-compression heating powered by low-voltage, pulsed cryogenic magnetic or inertial energy stores, outside the reactor core. The plasma has a density of about ${10}^{22}$ ${\mathrm{m}}^{\ensuremath{-}3}$ and $\ensuremath{\beta}$ values of nearly unity. In the power balance of the reactor, direct-conversion energy obtained by expansion of the burning high-$\ensuremath{\beta}$ plasma against the containing magnetic field is an important factor. No divertor is necessary since neutral-gas flow cools and replaces the "spent" plasma between pulses. The open-ended mirror reactor uses both thermal conversion of neutron energy and direct conversion of end-loss plasma energy to dc electrical power. A fraction of this direct-convertor power is then fed back to the ioninjection system to sustain the reaction and maintain the plasma. The average ion energy is 600 keV, plasma diameter 6 m, and the plasma beta 85%. The power levels of the three magnetic-confinement devices are in the 500-2000 MWe range, with the exception of the mirror reactor, for which the output is approximately 200 MWe. In Laser-Pellet reactors, frozen D-T pellets are ignited in a cavity which absorbs the electromagnetic, charged particle, and neutron energy from the fusion reaction. The confinement is "inertial," since the fusion reaction occurs during the disassembly of the heated pellet. A pellet-cavity unit would produce about 200 MWt in pulses with a repetition rate of the order of 10 ${\mathrm{sec}}^{\ensuremath{-}1}$. Such units could be clustered to give power plants with outputs in the range of 1000 MWe.
Control of non-self-adjoint distributed-parameter systems

Systems involving viscous damping forces, circulatory forces, and aerodynamic forces are non-self-adjoint. A method capable of controlling non-self-adjoint distributed systems is the independent modal-space control method, whereby the problem of controlling a distributed-parameter system is reduced to that of controlling an infinite set of independent, complex, second-order ordinary differential equations. In the case of optimal control, one must solve independent, complex, scalar Riccati equations. The transient solution of the Riccati equations can be found with relative ease and the steady-state solution can be found in closed form. A numerical example demonstrates the effectiveness of the method.
Dioxygen-copper reactivity: intermediacy of a peroxo-dicopper(II) (dioxygen-copper) complex in the hydroxylation reaction of a model mono-oxygenase system

Formation de l'intermediaire peroxo, avec 2 coordinats qui contiennent la meme unite tridentee amine-pyridyl
Synthesizing Exoplanet Demographics from Radial Velocity and Microlensing Surveys. II. The Frequency of Planets Orbiting M Dwarfs

In contrast to radial velocity (RV) surveys, results from microlensing surveys indicate that giant planets with masses greater than the critical mass for core accretion (∼0.1 M {sub Jup}) are relatively common around low-mass stars. Using the methodology developed in the first paper, we predict the sensitivity of M-dwarf RV surveys to analogs of the population of planets inferred by microlensing. We find that RV surveys should detect a handful of super-Jovian (>M {sub Jup}) planets at the longest periods being probed. These planets are indeed found by RV surveys, implying that the demographic constraints inferred from these two methods are consistent. Finally, we combine the results from both methods to estimate planet frequencies spanning wide regions of parameter space. We find that the frequency of Jupiters and super-Jupiters (1 ≲ m{sub p} sin i/M {sub Jup} ≲ 13) with periods 1 ≤ P/days ≤ 10{sup 4} is f{sub J}=0.029{sub −0.015}{sup +0.013}, a median factor of 4.3 (1.5-14 at 95% confidence) smaller than the inferred frequency of such planets around FGK stars of 0.11 ± 0.02. However, we find the frequency of all giant planets with 30 ≲ m{sub p} sin i/M {sub ⊕} ≲ 10{sup 4} and 1 ≤more » P/days ≤ 10{sup 4} to be f{sub G}=0.15{sub −0.07}{sup +0.06}, only a median factor of 2.2 (0.73-5.9 at 95% confidence) smaller than the inferred frequency of such planets orbiting FGK stars of 0.31 ± 0.07. For a more conservative definition of giant planets (50 ≲ m{sub p} sin i/M {sub ⊕} ≲ 10{sup 4}), we find f{sub G{sup ′}}=0.11±0.05, a median factor of 2.2 (0.73-6.7 at 95% confidence) smaller than that inferred for FGK stars of 0.25 ± 0.05. Finally, we find the frequency of all planets with 1 ≤ m{sub p} sin i/M {sub ⊕} ≤ 10{sup 4} and 1 ≤ P/days ≤ 10{sup 4} to be f{sub p} = 1.9 ± 0.5.« less
A New Class of Conformationally Rigid Analogues of 4-Amino-5-halopentanoic Acids, Potent Inactivators of γ-Aminobutyric Acid Aminotransferase

Recently, we found (Qiu, J.; Pingsterhaus, J. M.; Silverman, R. B. J. Med. Chem. 1999, 42, 4725−4728) that conformationally rigid analogues of the GABA aminotransferase (GABA-AT) inactivator vigabatrin were not inactivators of GABA-AT. To determine if this is a general phenomenon of GABA-AT inactivators, several mono- and di-halogen-substituted conformationally rigid analogues (7−15) of other GABA-AT inactivators, 4-amino-5-halopentanoic acids, were synthesized as potential inactivators of GABA-AT. Four of them, (+)-7, (−)-9, (+)-10, and (+)-15, were inactivators, although not as potent as the corresponding open-chain analogues. The maximal inactivation rate constants, kinact, for the fluoro- and bromo-substituted analogues were comparable, indicating that cleavage of the C−X bond is not rate determining. Consistent with that observation is the finding that [3-2H]-10 exhibits a deuterium isotope effect on inactivation of 3.3, suggesting that C−H bond cleavage is the rate-determining step. The rate of inac...
Mobile learning experience in the calculus classroom

Mobile technologies are ubiquitous in modern society, and college students find themselves increasingly immersed in their use. Is it possible to integrate this hand-held universe of mobile technology into the STEM classroom so that it becomes an organic, integral part of the 21st-century learning experience? Can mobile technology be used to enhance and improve the learning experience of students, one that develops both their technical and psycho-social skills? This paper discusses our attempt to do so at the South Dakota School of Mines and Technology, by developing a “mobile portal” through which instructors and students can access mobile content to supplement and expand the in-class learning environment.
What Can Be Learned from X-ray Spectroscopy Concerning Hot Gas in the Local Bubble and Charge Exchange Processes?

Both solar wind charge exchange emission and diffuse thermal emission from the Local Bubble are strongly dominated in the soft X-ray band by lines from highly ionized elements. While both processes share many of the same lines, the spectra should differ significantly due to the different production mechanisms, abundances, and ionization states. Despite their distinct spectral signatures, current and past observatories have lacked the spectral resolution to adequately distinguish between the two sources. High-resolution X-ray spectroscopy instrumentation proposed for future missions has the potential to answer fundamental questions such as whether there is any hot plasma in the Local Hot Bubble, and if so what are the abundances of the emitting plasma and whether the plasma is in equilibrium. Such instrumentation will provide dynamic information about the solar wind including data on ion species which are currently difficult to track. It will also make possible remote sensing of the solar wind.
Photoassisted Synthesis of Enantiopure Alkaloid Mimics Possessing Unprecedented Polyheterocyclic Cores

Enantiopure alkaloid mimics are synthesized via high yielding intramolecular cycloadditions of photogenerated azaxylylenes tethered to pyrroles, with further growth of molecular complexity via post-photochemical transformations of primary photoproducts. This expeditious access to structurally unprecedented polyheterocyclic cores is being developed in the context of diversity-oriented synthesis, as the modular design allows for rapid “pre-assembly” of diverse photoprecursors from simple building blocks/diversity inputs.
Interaction of X-rays with Bound Electrons

I. Change of wave-length of scattered x-rays. A previous analysis of scattered x-rays in this laboratory by means of the double crystal spectrometer showed fine structure in both the unmodified and modified lines. These fine structure lines were interpreted as being due to absorption of an amount of energy equal to the binding energy of the electrons in the scattering substance. Since then, other experimenters have failed to observe this phenomenon in scattered x-rays. The earlier work has been repeated using measuring apparatus having greater stability and sensitivity but with experimental conditions for producing the scattered radiation as nearly as possible like those of the earlier experiments. No fine structure was found though a line of intensity greater than 10 percent of molybdenum $\mathrm{K}{\ensuremath{\alpha}}_{1}$ unmodified could have been detected.II. Change of wave-length without scattering. A change of wave-length ascribed to this type of phenomenon without scattering has been reported by B. B. Ray and R. C. Majumdar. A number of experiments have been performed in an attempt to detect a change of wave-length of this type due to partial absorption of molybdenum $\mathrm{K}{\ensuremath{\alpha}}_{1}$ and copper $\mathrm{K}{\ensuremath{\alpha}}_{1,2}$ characteristic rays in the $K$-level of carbon. No indication of a modified line was found though a line of smaller intensity than that of the lines reported could have been detected. Two possible sources, other than a change of wave-length, are suggested which may give rise to lines of the type reported.
Tungsten disulfide: a novel hydrogen evolution catalyst for water decomposition

Silica-supported tungsten disulfide was prepared by the reaction of WO/sub 3//SiO/sub 2/ with H/sub 2/S at 300/sup 0/C. The WS/sub 2/ hexagonal structure was confirmed by X-ray diffraction analysis. AES and XPS studies show the existence of residual tungsten oxides in addition to WS/sub 2/. Hydrogen evolution properties of WS/sub 2//SiO/sub 2/ were determined by catalytic and photocatalytic (in the presence of fluorescein or CdS as sensitizers) tests and by electrochemical measurements. These were compared with silica-supported platinum. Although a graphite electrode immersed in a Pt/SiO/sub 2/ slurry evolved hydrogen at a more positive applied potential than in a WS/sub 2//SiO/sub 2/ slurry, silica-supported tungsten disulfide was more active and stable than Pt/SiO/sub 2/ for catalytic hydrogen production both in the dark and under visible light illumination (with cadmium sulfide as a sensitizer).
DDQ-mediated direct cross-dehydrogenative-coupling (CDC) between benzyl ethers and simple ketones.

A direct Cross-Dehydrogenative-Coupling (CDC) between benzyl ethers and simple ketones was developed without using any metal catalyst. By using DDQ, various benzyl ethers and simples ketones were coupled together directly to form β-alkoxyl ketones efficiently. A mechanism in which the DDQ serves the double roles of an oxidizing agent and an organomediator was proposed.
The viscosity of a dilute suspension of rough spheres

We consider the flow of a dilute suspension of equisized solid spheres in a viscous fluid. The viscosity of such a suspension is dependent on the volume fraction, c, of solid particles. If the particles are perfectly smooth, then solid spheres will not come into contact, because lubrication forces resist their approach. In this paper, however, we consider particles with microscopic surface asperities such that they are able to make contact. For straining motions we calculate the O(c²) coefficient of the resultant viscosity, due to pairwise interactions. For shearing motions (for which the viscosity is undetermined because of closed orbits on which the probability distribution is unknown) we calculate the c² contribution to the normal stresses N1 and N2. The viscosity in strain is shown to be slightly lower than that for perfectly smooth spheres, though the increase in the O(c) term caused by the increased effective radius due to surface asperities will counteract this decrease. The viscosity decreases with increasing contact friction coefficient. The normal stresses N1 and N2 are zero if the surface roughness height is less than a critical value of 0.000211 times the particle radius, and then become negative as the roughness height is increased above this value. N1 is larger in magnitude than N2.
Theater battle management core system lessons for systems engineers

The difficulties encountered during development of the theater battle management core system (TBMCS) provide lessons for systems engineering of large-scale, software-intensive systems. The absence of formal requirements and oversight, coupled with strong pressure for rapid deployment, caused the program to fail its first operational tests and actually delayed its deployment to the Held. The lack of measurable requirements and the need to integrate multiple third-party products and systems made it impossible to establish a system baseline and to test TBMCS in realistic conditions. Thus, significant problems manifested themselves only during official government tests. Moreover, despite nominal authority, the lead contractor had little or no control over the government-furnished elements and commercial off-the-shelf products that TBMCS was to incorporate. Experience with TBMCS leads to several conclusions. First, the more complex a system, the greater the need for rigor and discipline in engineering processes. Second, well-defined requirements are essential. Third, mandating the incorporation of specific third-party hardware or software may create severe problems for system development. Other lessons highlight the importance of open standards in a heterogeneous information technology environment and of layering with well-defined interfaces to facilitate integration and system evolution
Asymptotic methods in turbulent combustion

Introduction T are a number of different regimes of turbulent combustion, dependent upon the intensity and scales of the turbulence, measured with respect to suitable combustion parameters derived from the chemical reaction rates. In one set of these regimes, combustion occurs in thin reaction sheets, transported and distorted by the turbulence. In these reaction sheet regimes, more than one characteristic length scale is involved in the turbulent combustion; there are short scales associated with the chemical processes and long scales associated with the turbulence. The disparity of scales causes asymptotic methods to be advantageous for studying turbulent combustion in reaction sheet regimes. A significant amount of progress has been made recently by use of asymptotic methods for describing these regimes in both premixed and nonpremixed turbulent combustion. By and large, the objectives have been not to calculate the turbulent reacting flows completely, but rather to relate the properties of interest in these flows to properties of nonreacting turbulent flows. It then becomes possible to use the existing methods of analysis of nonreacting flows to calculate the results of interest for turbulent combustion. The intent of the present paper is to review the recent advances achieved by use of the methods described above and to identify not only what is known but also areas of unknowns for future research. Other reviews covering material of this type have been published.' The techniques employed in analyzing turbulent combustion differ for premixed and nonpremixed systems. This is especially true in various finer details of analyses of reaction sheet regimes. Therefore, it will be convenient here to treat turbulent premixed flames and turbulent diffusion flames separately. Presentations more unified in character may become appropriate in the future since there are a number of similarities, e.g., the reaction sheet aspect itself. However, it seems likely that certain essential differences will remain; burning velocities exist for premixed but not for nonpremixed combustion (at least not in the same sense).
Lunar resources - Evaluation and development for use in a lunar base program

The implications of lunar crust characteristics for human habitation on the moon are considered. Sources for propellants in the crust are discussed, and the rationale for including mining among base objectives is examined. Present opportunities for extracting lunar crust resources are addressed.
A charge transfer inefficiency correction model for the Chandra Advanced CCD Imaging Spectrometer

Soon after launch, the Advanced CCD Imaging Spectrometer (ACIS), one of the focal plane instruments on the Chandra X-ray Observatory, suffered radiation damage from exposure to soft protons during passages through the Earth's radiation belts. The primary effect of the damage was to increase the charge transfer inefficiency (CTI) of the eight front illuminated CCDs by more than two orders of magnitude. The ACIS instrument team is continuing to study the properties of the damage with an emphasis on developing techniques to mitigate CTI and spectral resolution degradation. We will discuss the characteristics of the damage, the detector and the particle background and how they conspire to degrade the instrument performance. We have developed a model for ACIS CTI which can be used to correct each event and regain some of the lost performance. The correction uses a map of the electron trap distribution, a parameterization of the energy dependent charge loss and the fraction of the lost charge re-emitted into the trailing pixel to correct the pixels in the event island. This model has been implemented in the standard Chandra data processing pipeline. Some of the correction algorithm was inspired by the earlier work on ACIS CTI correction by Townsley and collaborators. The details of the CTI model and how each parameter improves performance will be discussed, as well as the limitations and the possibilities for future improvement.
Computing the Permanent of (Some) Complex Matrices

We present a deterministic algorithm, which, for any given $$0< \epsilon < 1$$0<∈<1 and an $$n \times n$$n×n real or complex matrix $$A=\left( a_{ij}\right) $$A=aij such that $$\left| a_{ij}-1 \right| \le 0.19$$aij-1≤0.19 for all $$i, j$$i,j computes the permanent of $$A$$A within relative error $$\epsilon $$∈ in $$n^{O\left( \ln n -\ln \epsilon \right) }$$nOlnn-ln∈ time. The method can be extended to computing hafnians and multidimensional permanents.
Inflation targeting or fear of floating in disguise: the case of Mexico

This paper uses simple analytics to show the similarities and differences between inflation targeting and fear of floating in emerging markets. The analytics provide well-defined predictions for the behaviour of exchange rates and relevant monetary variables under both regimes. This allows us to distinguish clearly one regime from another and empirically test whether or not a country that targets inflation also exhibits a fear of floating. We analyse the recent experience in Mexico where the authorities now claim to be following an inflation targeting regime. Mexico is also one of the countries claimed to exhibit a fear of floating. Using data from Banco de Mexico, we first confirm that by standard measures Mexico exhibits fear of floating. Second, we show that Mexico is inflation targeting and discuss the relationship and test for a distinction between the two. Finally, we conclude by discussing our results and their implications for other emerging market inflation targeters. Copyright © 2004 John Wiley & Sons, Ltd.
The $L^{p}$ regularity problem on Lipschitz domains

This paper contains two results on the L p regularity problem on Lipschitz domains. For second order elliptic systems and 1 2, the solvability of the L p regularity problem is equivalent to a weak reverse Holder condition with exponent p.
Are graduate students rational? Evidence from the market for biomedical scientists.

The U.S. National Institutes of Health (NIH) budget expansion from 1998 through 2003 increased demand for biomedical research, raising relative wages and total employment in the market for biomedical scientists. However, because research doctorates in biomedical sciences can often take six years or more to complete, the full labor supply response to such changes in market conditions is not immediate, but rather is observed over a period of several years. Economic rational expectations models assume that prospective students anticipate these future changes, and also that students take into account the opportunity costs of their pursuing graduate training. Prior empirical research on student enrollment and degree completions in science and engineering (S&E) fields indicates that “cobweb” expectations prevail: that is, at least in theory, prospective graduate students respond to contemporaneous changes in market wages and employment, but do not forecast further changes that will arise by the time they complete their degrees and enter the labor market. In this article, we analyze time-series data on wages and employment of biomedical scientists versus alternative careers, on completions of S&E bachelor's degrees and biomedical sciences PhDs, and on research expenditures funded both by NIH and by biopharmaceutical firms, to examine the responsiveness of the biomedical sciences labor supply to changes in market conditions. Consistent with previous studies, we find that enrollments and completions in biomedical sciences PhD programs are responsive to market conditions at the time of students' enrollment. More striking, however, is the close correspondence between graduate student enrollments and completions, and changes in availability of NIH-funded traineeships, fellowships, and research assistantships.
New cembradiene diterpenoids from an undescribed Caribbean gorgonian of the genus Eunicea

Abstract Five new cembradiene diterpenoids (1–5) and two previously known compounds (7 and 8) have been isolated from an undescribed Caribbean gorgonian of the genus Eunicea. The structures of these compounds were assigned on the basis of chemical and spectral studies, and the relative stereochemistry of cembradiene 3 was defined by X-ray crystallographic methods.
Mostly-unsupervised statistical segmentation of Japanese Kanji sequences

Given the lack of word delimiters in written Japanese, word segmentation is generally considered a crucial first step in processing Japanese texts. Typical Japanese segmentation algorithms rely either on a lexicon and syntactic analysis or on pre-segmented data; but these are labor-intensive, and the lexico-syntactic techniques are vulnerable to the unknown word problem. In contrast, we introduce a novel, more robust statistical method utilizing unsegmented training data. Despite its simplicity, the algorithm yields performance on long kanji sequences comparable to and sometimes surpassing that of state-of-the-art morphological analyzers over a variety of error metrics. The algorithm also outperforms another mostly-unsupervised statistical algorithm previously proposed for Chinese. Additionally, we present a two-level annotation scheme for Japanese to incorporate multiple segmentation granularities, and introduce two novel evaluation metrics, both based on the notion of a compatible bracket, that can account for multiple granularities simultaneously.
Comments on an Attempted Synthesis of 1-Aminocyclopropane-1,2-Dicarboxylic Acid

Abstract Aminolysis of dimethyl 1-bromocyclopropane-1,2-dicarboxylate in the presence of KHMDS was reinvestigated. Dimethyl 1-methoxycyclopropane-1,2-dicarboxylate instead of the putative dimethyl 1-aminocyclopropane-1,2-dicarboxylate was isolated from the reaction.
Development of Statistical Typhoon Intensity Prediction: Application to Satellite-Observed Surface Evaporation and Rain Rate (STIPER)

AbstractA statistical–dynamical model has been used for operational guidance for tropical cyclone (TC) intensity prediction. In this study, several multiple linear regression models and neural network (NN) models are developed for the intensity prediction of western North Pacific TCs at 24-, 48-, and 72-h intervals. The multiple linear regression models include a model of climatology and persistence (CLIPER), a model based on the Statistical Typhoon Intensity Prediction System (STIPS), which serves as the base regression model (BASE), and a model of STIPS with additional satellite estimates of surface evaporation (SLHF) and inner-core rain rate (IRR, STIPER model). A revised equation for the TC maximum potential intensity is derived using Tropical Rainfall Measuring Mission Microwave Imager optimally interpolated sea surface temperature data, which have higher temporal and spatial resolutions. Analyses of the resulting models show the marginal improvement of STIPER over BASE. However, IRR and SLHF are fou...
Spectroscopic ellipsometry characterization of thin-film silicon nitride

We have measured and analyzed the optical characteristics of a series of silicon nitride thin films prepared by plasma-enhanced chemical vapor deposition on silicon substrates for photovoltaic applications. Spectroscopic ellipsometry measurements were made by using a two-channel spectroscopic polarization modulator ellipsometer that measures N. S, and C data simultaneously. The data were fit to a model consisting of air/roughness/SiN/crystallin silicon. The roughness was modeled using the Bruggeman effective medium approximation, assuming 50% SiN, 50% voids. The optical functions of the SiN film were parameterized using a model by Jellison and Modine (Appl. Phys. Lett. 69 (1996) 371; 69 (1996) 2137). All the x 2 are near 1, demonstrating that this model works extremely well for all SiN films. The measured dielectric functions were used to make optimized SiN anti-reflection coatings for crystalline silicon solar cells. © 1998 Elsevier Science S.A.
A noncoherent coded modulation for 16QAM

We present a noncoherent coded 16QAM (NC-16QAM) scheme by modifying the trellis-coded 16QAM (TC-16QAM) scheme. Our simulation results show that the performance of the NC-16QAM with noncoherent detection is close to the one of the original TC-16QAM with coherent detection. The NC-16QAM is an extension of the NC-8PSK previously obtained by Wei and Lin (see IEEE Commun. Lett., vol.2. p.260-62, 1998). A noncoherent initial phase estimation algorithm is also proposed.
Locally Decodable Codes

Over 60 years of research in coding theory, that started with the works of Shannon and Hamming, have given us nearly optimal ways to add redundancy to messages, encoding bit strings representing messages into longer bit strings called codewords, in a way that the message can still be recovered even if a certain fraction of the codeword bits are corrupted. Classical error-correcting codes, however, do not work well when messages are modern massive datasets, because their decoding time increases (at least) linearly with the length of the message. As a result in typical applications large datasets are first partitioned into small blocks, each of which is then encoded separately. Such encoding allows efficient randomaccess retrieval of the data, but yields poor noise resilience. Locally decodable codes are codes intended to address this seeming conflict between efficient retrievability and reliability. They are codes that simultaneously provide efficient random-access retrieval and high noise resilience by allowing reliable reconstruction of an arbitrary data bit from looking at only a small number of randomly chosen codeword bits. Apart from the natural application to data transmission and storage such codes have important applications in cryptography and computational complexity theory. This review introduces and motivates locally decodable codes, and discusses the central results of the subject. Locally Decodable Codes assumes basic familiarity with the properties of finite fields and is otherwise self-contained. It will benefit computer scientists, electrical engineers, and mathematicians with an interest in coding theory.
On the deformation quantization description of matrix compactifications

Abstract Matrix theory compactifications on tori have associated Yang-Mills theories on the dual tori with sixteen supercharges. A non-commutative description of these Yang-Mills theories based in deformation quantization theory is provided. We show that this framework allows a natural generalization of the ‘Moya B -deformation’ of the Yang-Mills theories to non-constant background B -fields on curved spaces. This generalization is described through Fedosov's geometry of deformation quantization.
Calcium in Food Fortification Strategies

Calcium fortified foods are likely to play an increasingly important role in helping consumers achieve newer calcium requirements aimed at reducing the risk of osteoporosis. The fortificant of choice should be well absorbed and beneficial in building peak bone mass during growth and protecting against bone loss later in life. Calcium absorption can be influenced by constituents present in the food and perhaps improved with addition of enhancers. The calcium source must also be compatible with the food being fortified which relates to solubility of the salt, concentration of calcium in the formula, processing stability, and flavour profile.
Rationalizable Predatory Pricing

Abstract This paper shows that predatory pricing is rationalizable and is in this sense rational even when there is no uncertainty regarding structural parameters such as cost or demand. Predatory pricing is modelled as a war of attrition. All strategy profiles—including all possible lengths of predatory battles—are rationalizable in the extensive form. Despite this, weak restrictions on beliefs combined with rationalizability have drastic implications for the play of the game.Journal of Economic LiteratureClassification Numbers: C72, C73, L12, L41.
THE METALLICITY OF INTERGALACTIC GAS IN COSMIC VOIDS

We have used the Hubble/STIS and FUSE archives of ultraviolet spectra of bright AGN to identify intergalactic Lyabsorbers in nearby (z ≤0.1) voids. From a parent sample of 651 Ly� absorbers, we identified 61 "void absorbers" located > 1.4h −1 70 Mpc from the nearest L* or brighter galaxy. Searching for metal absorption in high-quality (S/N> 10) spectra at the location of three diagnostic metal lines (O VI �1032, C IV �1548, Si III �1206), we detected no metal lines in any individual absorber, or in any group of absorbers using pixel co-addition techniques. The best limits on metal-line absorption in voids were set using four strong Lyabsorbers with NHI > 10 14 cm −2 , with 3� equivalent-width limits ranging from 8 mu (O VI), 7-15 mu (C IV), and 4-10 mu (Si III). Photoionization modeling yields metallicity limits Z < 10 −1.8±0.4 Z⊙ from non-detections of C IV and O VI, some ∼ 6 times lower than those seen in Ly�/O VI absorbers at z < 0.1. Although the void Lyabsorbers could be pristine material, considerably deeper spectra are required to rule out a "universal metallicity floor" produced by bursts of early star formation, with no subsequent star formation in the voids. The most consistent conclusion derived from these low-z results, and similar searches at z = 3 − 5, is that galaxy filaments have increased their mean IGM metallicity by factors of 30-100 since z ∼ 3.
6D IONIZATION MUON COOLING WITH TABLETOP RINGS

Progress on six dimensional ionization muon cooling with relatively small rings of magnets is described. Lattices being explored include scaling sector cyclotrons with edge focusing and strong focusing, fixed field alternating gradient (FFAG) rings. Ionization cooling is provided by high pressure hydrogen gas which removes both transverse and longitudinal momentum. Lost longitudinal momentum is replaced using radio frequency (RF) cavities, giving a net transverse emittance reduction. The longer path length in the hydrogen of higher momentum muons decreases longitudinal emittance at the expense of transverse emittance. Thus emittance exchange allows these rings to cool in all six dimensions and not just transversely. Alternatively, if the RF is located after the ring, it may be possible to cool the muons by stopping them as they spiral adiabatically into a central swarm. As p → 0, Δp → 0. The resulting cooled muons can lead to an intense muon beam which could be a source for neutrino factories or muon colliders.
On the Space-Time Uncertainty Principle and Holography

Abstract In this note further evidence is collected in support of the claim that the space-time uncertainty principle implies holography, both within the context of Matrix theory and the framework of the proposed duality between certain conformal field theories and M-theory/string theory on AdS backgrounds.
Light-front aspects of chiral symmetry

Abstract Spontaneous chiral symmetry breaking and axial anomaly are studied in the light-front formulation. The existence of multiple vacua and a Nambu-Goldstone boson, both related to dynamical fermion zero modes, are demonstrated within a simple sigma model with fermions. The Weyl gauge formulation and a consistent gauge invariant point-splitting regularization, which includes the light front time, are crucial for obtaining the anomaly in the massive Schwinger model and QED(3+1).
UTILIZING PARAMETRIC HYPERPATCH METHODS FOR MODELING AND DISPLAY OF FREE-FORM SOLIDS

This paper introduces methods of creating, modifying and visualizing free-form geometric models, by use of the B-spline hyperpatch. Modeling tools for the hyperpatch, including local control-point interactions, lofting operations and sweeping operations, are described. These operations, together with modeling tools generated for free-form surface design, form a powerful tool hierarchy for the design of complex solids. Techniques are also described by which these hyperpatches may be integrated into conventional visible-surface algorithms. With the defined methods, and the hyperpatch model, the complexity of free-form solid object construction was found to be significantly simplified.
Vagueness in Context

This paper argues that whether an utterance of a vague term makes any contribution to propositional content is context-sensitive and that attention to this fact allows for an attractive solution to the sorites paradox.
INTERMOLECULAR ALDOL REACTIONS VIA ALLYLIC O-STANNYL KETYLS

Abstract A mild and neutral free radical reaction of an α,β-unsaturated ketone and tributyltin radical produced a resonance-stabilized allylic O-stannyl ketyl intermediate. A tin(IV) enolate, produced by subsequent hydrogen atom transfer, was next quenched with various aldehydes to yield an aldol product which was readily eliminated with p -toluenesulfonic acid to afford new α,β-unsaturated ketones with E/Z ratios up to > 100:1.
Local Density of States in Double-Barrier Resonant Tunneling Structures.

We calculate the local density of states between the barriers of a double-barrier resonant-tunneling structure within the context of a simplified model. As the area of the barriers increases, there is a smooth crossover in the density of states from a three-dimensional (3D) square-root-of-energy behavior to a 2D steplike behavior. The local 1D density of states corresponding to a fixed electron momentum transverse to the barriers is also calculated and shows sharp peaks at energies corresponding to the quasibound states between the wells. The width of the lowest quasibound state is computed as a function of barrier area.
Quartic gauge boson couplings at linear colliders: Interplay of WWZ / ZZZ production and WW fusion

Abstract We study new physics effects to the quartic gauge boson couplings formulated by the electroweak chiral Lagrangian. Five next-to-leading order operators characterize the anomalous quartic gauge interactions which involve pure Goldstone boson dynamics for the electroweak symmetry breaking. We estimate the typical size of these couplings in different strongly-interacting models and examine the sensitivity to directly probing them via the WWZ / ZZZ triple gauge boson production at the high energy linear colliders. The important roles of polarized e − and e + beams are stressed. We then compare the results with those from the W -pair production of the WW -fusion processes, and analyze the interplay of these two production mechanisms for an improved probe of the quartic gauge boson interactions.
Mechanism of methane formation in potassium catalyzed carbon gasification

Abstract We have performed a kinetics and isotope tracer study of the mechanism of CH4 formation from a potassium catalyzed carbon during gasification in atmospheres containing H2O, H2, CO2, and CO Temperatures from 925 to 1025 K and pressures up to 8 atm were studied. We found that although potassium salts catalyze the formation of CH4, there is not a one-to-one correspondence between CH4 and CO formation rates implying different sites for generation of the two products. At low gas phase carbon activity the CH4 product is formed by direct hydrogenation of substrate carbon and not by secondary reaction of gas phase CO or CO2. At higher gas phase carbon activities some CH4 is produced from gas phase carbon oxides as a result of carbon deposition. In some cases the deposited carbon shows higher reactivity than the original carbon substrate so that this can be legitimately viewed as a secondary pathway.
Time-varying risk premia and the cost of capital: An alternative implication of the Q theory of investment

Abstract Evidence suggests that expected excess stock market returns vary over time, and that this variation is much larger than that of expected real interest rates. It follows that a large fraction of the movement in the cost of capital in standard investment models must be attributable to movements in equity risk-premia . In this paper we emphasize that such movements in equity risk premia should have implications not merely for investment today, but also for future investment over long horizons. In this case, predictive variables for excess stock returns over long-horizons are also likely to forecast long-horizon fluctuations in the growth of marginal Q , and therefore investment. We test this implication directly by performing long-horizon forecasting regressions of aggregate investment growth using a variety of predictive variables shown elsewhere to have forecasting power for excess stock market returns.
N-Acylsulfonamide Assisted Tandem C−H Olefination/Annulation: Synthesis of Isoindolinones

A tandem C-H olefination/annulation sequence directed by N-acylsulfonamides affords a variety of isoindolinones. This transformation is compatible with aliphatic alkenes as well as conjugated alkenes. Notably, molecular oxygen can be used as the sole, eco-friendly oxidant.
Classically Rationalized Low-Order, Robust Structural Controllers

An experimental and analytical comparison of classically rationalized and optimal control design techniques is conducted. Classically rationalized compensators blend the loop assignments, complex topological design, and robustness of optimal controllers and the lower order, robustness, and practical insight of classical controllers. The single-input/single-output disturbance rejection problem for controlled structures is divided into four distinct topologies, and optimal controllers aredesignedand interpreted classically.Theobservationsarethen summarized into a set of design rules forthedesign oflow-order robustcontrollers. Classically rationalized and robust compensators are experimentally implemented on the Middeck Active Control Experiment, a Shuttle e ight experiment
GENERAL ANALYSIS OF TYPE I PLANETARY MIGRATION WITH STOCHASTIC PERTURBATIONS

This paper presents a generalized treatment of Type I planetary migration in the presence of stochastic perturbations. In many planet-forming disks, the Type I migration mechanism, driven by asymmetric torques, acts on a short timescale and compromises planet formation. If the disk also supports magnetohydrodynamics instabilities, however, the corresponding turbulent fluctuations produce additional stochastic torques that modify the steady inward migration scenario. This work studies the migration of planetary cores in the presence of stochastic fluctuations using complementary methods, including a Fokker-Planck approach and iterative maps. Stochastic torques have two main effects. (1) Through outward diffusion, a small fraction of the planetary cores can survive in the face of Type I inward migration. (2) For a given starting condition, the result of any particular realization of migration is uncertain, so that results must be described in terms of the distributions of outcomes. In addition to exploring different regimes of parameter space, this paper considers the effects of the outer disk boundary condition, varying initial conditions, and time dependence of the torque parameters. For disks with finite radii, the fraction of surviving planets decreases exponentially with time. We find the survival fractions and decay rates for a range of disk models, and find the expected distribution of locations for surviving planets. For expected disk properties, the survival fraction lies in the range 0.01 < pS < 0.1.
Superconducting quantum phase transitions tuned by magnetic impurity and magnetic field in ultrathin a-Pb films

Superconducting quantum phase transitions tuned by disorder (d), paramagnetic impurity (MI) and perpendicular magnetic field (B) have been studied in homogeneously disordered ultrathin a-Pb films. The MI-tuned transition is characterized by progressive suppression of the critical temperature to zero and a continuous transition to a weakly insulating normal state with increasing MI density. In all important aspects, the d-tuned transition closely resembles the MI-tuned transition and both appear to be fermionic in nature. The B-tuned transition is qualitatively different and probably bosonic. In the critical region it exhibits transport behavior that suggests a B-induced mesoscale phase separation and presence of Cooper pairing in the insulating state.
Expectations and exchange rate dynamics after a decade of floating

Abstract Dornbusch's model of expectations and exchange rate dynamics has been a theoretical success and an empirical failure. The premise underlying this paper is that the price and exchange rate dynamics inherent in his model cannot be captured by single equation methods. To capture these dynamics, we estimate Dornbusch's model using constrained maximum likelihood methods which incorporate cross equation restrictions derived from the structural equations and assumption of rational expectations. Our central result is that the estimation of Dornbusch's model is much more successful than single equation methods have led us to believe.
Surface infrared reflection-absorption spectroscopy using a tunable diode laser

Abstract Single-reflection infrared reflection-absorption spectra (IRRAS) of adsorbates on surfaces have been obtained using a tunable diode laser radiation source. Surface sensitivity is achieved through the use of polarization modulation, and the high brightness of the laser light source has made possible the observation of vibrational modes at energies much lower than those accessible with conventional blackbody sources. Results are presented for the chemisorption of oxygen on polycrystalline aluminum showing surface (580 cm-1) and subsurface (890 cm-1) AlO stretching modes at sub-monolayer coverage.
Finite temperature quark confinement via chromomagnetic fields

Abstract A natural mechanism for finite temperature quark confinement arises via the coupling of the adjoint.Polyakov loop to the chromamagnetic field. Lattice simulations and analytical results both support this hypothesis. Finite temperature SU(3) lattice simulations show that a large external coupling to the chromomagnetic field restores confinement at temperatures above the normal deconfining temperature. A one-loop calculation of the effective potential for SU(2) gluons in a background field shows that a constant chromomagnetic field can drive the Polyakov loop to confining behavior, and the Polyakov loop can in turn remove the well-known tachyonic mode associated with gluons in an external chromomagnetic field. For abelian background fields, tachyonic modes are necessary for confinement at one loop.
REACTION OF SO2 WITH CESIUM AND CESIUM-PROMOTED ZNO AND MOO2

The chemistry of SO2 on pure metallic Cs and Cs-promoted polycrystalline surfaces of ZnO and MoO2 has been studied using high-resolution synchrotron-based photoemission. Metallic cesium reacts vigorously with SO2 at temperatures between 100 and 300 K. At 100 K, the amount of SO2 that fully dissociates (SO2,gas → Sa + 2Oa) on the alkali metal is relatively small, and SOx (x = 2−4) species predominate on the surface. SO3 and SO4 may be formed as a result of the reaction of SO2 with atomic oxygen (SO2 + nOa → SO2+n,a where n = 1−2), or by disproportionation of chemisorbed SO2. At 300 K the stability of the CsSOx species is lower than at 100 K, and the formation of CsOy and CsSy becomes important. In the Cs/ZnO and Cs/MoO2 systems, the alkali ↔ oxide interactions are very strong. Despite this, the supported Cs atoms retain a large chemical affinity for SO2 and are able to enhance the rate of adsorption of the molecule on the oxide surfaces, even at low coverages (0.1−0.2 ML) of cesium when the alkali atoms ar...
Cross Section Measurements with Monoenergetic Muon Neutrinos

The monoenergetic 236 MeV muon neutrino from charged kaon decay at rest (${K}^{+}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\nu}}_{\ensuremath{\mu}}$) can be used to produce a novel set of cross section measurements. Applicable for short- and long-baseline accelerator-based neutrino oscillation experiments, among others, such measurements would provide a ``standard candle'' for the energy reconstruction and interaction kinematics relevant for charged current neutrino events near this energy. This neutrino can also be exercised as a unique known-energy, purely weak interacting probe of the nucleus. A number of experiments are set to come online in the next few years that will be able to collect and characterize thousands of these events.