cssi/SciSciGPT-SciSciNet huggingface dataset:
Frequency dependence of the spin glass freezing temperatures in icosahedral R–Mg–Zn (R = rare earth) quasicrystals

We present ac susceptibility measurements with the frequency spanning three orders of magnitude on single grain, icosahedral R–Mg–Zn (R = rare earth) quasicrystals. The freezing temperature in Gd-based, Heisenberg spin glasses in this family increases by ∼2% with a frequency increase from 10 Hz to 10 kHz, whereas the freezing temperature in the non-Heisenberg members of the family is significantly more responsive to the frequency change (by 16–22%), suggesting that an additional magnetic anisotropy distribution in the non-Heisenberg spin glasses causes changes in the low frequency magnetic dynamics.
Large-scale and facile preparation of pure ammonia borane through displacement reactions.

Ammonia borane (AB) is the most widely studied hydride for hy- drogen storage in addition to being a useful reducing agent. Attempts to syn- thesize pure AB through simple dis- placement reactions date back to the 1960s; but have been thwarted by the formation of the diammoniate of dibor- ane (DADB), an ionic byproduct. Based on our recent characterization of the formation mechanism of DADB, we have developed a large-scale syn- thesis of pure AB by both increasing the basicity of the Lewis base of the borane carrier and using a nonpolar solvent to limit the formation of an in- termediate, the ammonia diborane (AaDB). Conditions were optimized for the preparation of pure AB by two displacement reactions, either ammonia with dimethylsulfide borane or ammo- nia with dimethylaniline borane in tol- uene at room temperature. These pro- cedures are also suitable for prepara- tion of other amine boranes which had the same problem of forming ionic by- products during displacement reactions.
Mixed higgsino dark matter from a large SU(2) gaugino mass

We observe that in SUSY models with non-universal GUT scale gaugino mass parameters, raising the GUT scale SU(2) gaugino mass |M2| from its unified value results in a smaller value of ?mHu2 at the weak scale. By the electroweak symmetry breaking conditions, this implies a reduced value of ?2 vis ? vis models with gaugino mass unification. The lightest neutralino can then be mixed Higgsino dark matter with a relic density in agreement with the measured abundance of cold dark matter (DM). We explore the phenomenology of this high |M2| DM model. The spectrum is characterized by a very large wino mass and a concomitantly large splitting between left- and right- sfermion masses. In addition, the lighter chargino and three light neutralinos are relatively light with substantial higgsino components. The higgsino content of the LSP implies large rates for direct detection of neutralino dark matter, and enhanced rates for its indirect detection relative to mSUGRA. We find that experiments at the LHC should be able to discover SUSY over the portion of parameter space where m 2350?2750 GeV, depending on the squark mass, while a 1 TeV electron-positron collider has a reach comparable to that of the LHC. The dilepton mass spectrum in multi-jet + ?+??+ETmiss events at the LHC will likely show more than one mass edge, while its shape should provide indirect evidence for the large higgsino content of the decaying neutralinos.
Quasar Candidates in the Hubble Deep Field

The Hubble Deep Field (HDF) gives us an unprecedented view of our universe and an opportunity to study a wide range of questions in galaxy evolution and cosmology. Here we focus on the search for unresolved faint quasars and active galactic nuclei (AGNs) in the crude combine images using a multicolor imaging analysis that has proved very successful in recent years. Quasar selection was carried out both in multicolor space and in "profile space." The latter is the multiparameter space formed by the radial profiles of the objects in the different images. By combining the dither frames available for each filter, we were able to obtain well-sampled radial profiles of the objects and measure their deviation from that of a stellar source. This procedure efficiently helps to overcome the problems caused by the WPFC2 undersampling. Furthermore, to identify areas of multicolor space where quasars might be expected, we generated synthetic quasar spectra in the range 1.0 3.5. We find more quasar candidates than previous work because of our more extensive modeling and use of the color information. Spectroscopic observations of the candidates are needed to determine which, if any, are quasars or AGNs.
Treatment of Systemic Sclerosis

Systemic sclerosis is an extremely variable disease in its manifestations and consequently, treatment needs to be individualized depending on the specific problems that each patient has. Limited scleroderma patients have a prolonged duration of Raynaud’s phenomenon and puffy fingers before they develop any skin thickening, digital ulcers or gastrointestinal symptoms. They are likely to present with all the classic manifestations of scleroderma. Diffuse scleroderma patients have a much more acute systemic onset with marked whole hand swelling and may initially have only subtle skin thickening. A good understanding of the differences between the natural history of limited and diffuse scleroderma will enable the physician to treat present problems and anticipate future ones more effectively. One should determine which major subset and organ systems are involved before deciding on the appropriate therapy. Advances in organ-specific therapy, particularly calcium channel antagonists in Raynaud’s phenomenon, proton pump inhibitors in esophageal reflux, intravenous iloprost and endothelin receptor antagonists in pulmonary hypertension, and ACE inhibitors in renal crisis, have decreased morbidity and mortality in patients with scleroderma. Studies of aggressive therapies to prevent or improve pulmonary fibrosis are in progress. Further clinical experience in wound healing, gastrointestinal malabsorption and physical therapy for loss of motion has helped patients to have a more comfortable life. In recent years, a significant number of controlled clinical trials have been performed and there has been improved understanding of the best way to perform studies and of which patients are most likely to respond to therapy. Penicillamine, methotrexate, photopheresis, relaxin, interferons, and cyclosporine have all been studied in controlled trials with variable outcomes. Although an overall remittive therapy has not yet been determined, new, potentially useful agents are being investigated.
Automatic scale detection

Most image processing and computer vision algorithms assume knowledge of the proper spatial scale in the image. We propose an automatic technique that adaptively sets the proper spatial scale based on the size of local features in the image. We discuss an analog VLSI circuit implementation that uses this method to automatically determine the proper scale based on a dynamic system model that continuously searches scale space. Though this technique is motivated by analog circuit concepts, we show results for a digital implementation for image enhancements of mammograms. Digital implementations must discretize the scale space and perform an optimization over this finite set.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
Temperature-Dependent Damping and Frequency Shifts in Collective Excitations of a Dilute Bose-Einstein Condensate

We extend to finite temperature the study of collective excitations of a Bose-Einstein condensate in a dilute gas of ${}^{87}\mathrm{Rb}$. Measurements of two modes with different angular momenta show unexpected temperature-dependent frequency shifts, with very different behavior for the two symmetries; in addition there is a sharp feature in the temperature dependence of one mode. The damping of these excitations exhibits dramatic temperature dependence, with condensate modes at temperatures near the transition damping even faster than analogous noncondensate oscillations.
Isomonodromy transformations of linear systems of difference equations

We introduce and study ?isomonodromy? transformations of the matrix linear difference equation Y (z + 1) = A(z)Y (z) with polynomial A(z). Our main result is construction of an isomonodromy action of Zm(n+1)-1 on the space of coefficients A(z) (here m is the size of matrices and n is the degree of A(z)). The (birational) action of certain rank n subgroups can be described by difference analogs of the classical Schlesinger equations, and we prove that for generic initial conditions these difference Schlesinger equations have a unique solution. We also show that both the classical Schlesinger equations and the Schlesinger transformations known in isomonodromy theory, can be obtained as limits of our action in two different limit regimes. Similarly to the continuous case, for m = n = 2 the difference Schlesinger equations and their q-analogs yield discrete Painlev?e equations; examples include dPII, dPIV, dPV, and q-PVI.
A General, Efficient, and Inexpensive Catalyst System for the Coupling of Aryl Iodides and Thiols

An efficient copper-catalyzed carbon−sulfur bond formation reaction was developed. This method is particularly noteworthy given its experimental simplicity, high generality, and exceptional level of functional group toleration and the low cost of the catalyst system.
The coarse geometric Novikov conjecture and uniform convexity

Abstract The coarse geometric Novikov conjecture provides an algorithm to determine when the higher index of an elliptic operator on a noncompact space is nonzero. The purpose of this paper is to prove the coarse geometric Novikov conjecture for spaces which admit a (coarse) uniform embedding into a uniformly convex Banach space.
5-Endo-dig electrophilic cyclization of 1,4-disubstituted but-3-yn-1-ones: regiocontrolled synthesis of 2,5-disubstituted 3-bromo- and 3-iodofurans.

5-Endo-dig electrophilic cyclization of 1,4-diaryl but-3-yn-1-ones with N-bromosuccinimide or N-iodosuccinimide/acetone and iodine monochloride/CH2Cl2, at room temperature, in the absence of base, provides 3-halo-2,5-diarylfurans with excellent regiocontrol and high yields (81−94%).
Newton's method as a dynamical system: Global convergence and predictability

Abstract Newton's method as an iterative scheme to compute both unstable and stable fixed points of a discrete dynamical system is considered. It is shown for Newton iteration that the basins of attraction are intertwinted in a complicated manner. This complex structure appears to fractal, and its dimension is estimated. Consequences for predictability for the final state are given in terms of imprecision in the initial data.
Non-linear, finite frequency quantum critical transport from AdS/CFT

Transport at a quantum critical point depends sensitively on the relative magnitudes of temperature, frequency and electric field. Here we used the gauge/gravity correspondence to compute the full temperature and, generally nonlinear, electric field dependence of the electrical conductivity for some model critical theories. In the special case of 2 + 1 dimensions we are also able to find the full time-dependent response of the system to an arbitrary time dependent external electric field. The response of the system is instantaneous, implying a frequency independent conductivity. We describe a mechanism that rationalizes the instantaneous response.
Charging and coagulation of dust in protoplanetary plasma environments

Combining a particle-particle, particle-cluster, and cluster-cluster agglomeration model with an aggregate charging model, the coagulation and charging of dust particles in plasma environments relevant for protoplanetary disks have been investigated, including the effect of electron depletion in high dust density environments. The results show that charged aggregates tend to grow by adding small particles and clusters to larger particles and clusters, and that cluster-cluster aggregation is significantly more effective than particle-cluster aggregation. Comparisons of the grain structure show that with increasing aggregate charge the compactness factor, σ, decreases and has a narrower distribution, indicating a fluffier structure. Neutral aggregates are more compact, with larger σ, and exhibit a larger variation in fluffiness. Overall, increased aggregate charge leads to larger, fluffier, and more massive aggregates.
Magnetic Braking Revisited

We present a description for the angular momentum loss rate due to magnetic braking for late-type stars, taking into account recent observational data on the relationship between stellar activity and rotation. The analysis is based on an idealized two-component coronal model subject to constraints imposed on the variation of the coronal gas density, with a rotation period inferred from the observed variation of X-ray luminosity LX with rotation rate Ω (LX ∝ Ω2) for single rotating dwarfs. An application of the model to high rotation rates leads to a gradual turnover of the X-ray luminosity that is similar to the saturation recently observed in rapidly rotating dwarfs. The resulting angular momentum loss rate, , depends on Ω in the form ∝ Ωβ, where β ~ 3 for slow rotators and ~1.3 for fast rotators. The relation at high rotation rates significantly differs from the power-law exponent for slowly rotating stars, depressing the angular momentum loss rate without necessarily requiring the saturation of the magnetic field. The application of this model to the evolution of cataclysmic variable binary systems leads to mass transfer rates that are more in accordance with those observed compared to rates based on either a Skumanich law or an empirical law based on β = 1.
iCOACH: A circuit optimization aid for CMOS high-performance circuits

iCOACH is a two-pass iterative circuit optimizer which generates a polycell-based layout from a gate level description file and user-defined timing constraints. The first pass is to generate, place and route the cells and extract the interconnection parameters. The second pass optimizes the circuit at the transistor level and makes necessary layout adjustments including pitch-matchings. Although iCOACH has the layout style similar to the polycell approach, it is distinct in two important aspects. First, iCOACH does not rely on any fixed cell library. Instead iCOACH generated customized cells by invoking the circuit optimizer and performs the transistor-level optimization for both static and dynamic CMOS circuits and their layouts under realistic constraints. Secondly, although the cells in the same row are required to have the same height, different rows can have different heights to make circuit more compact. Dynamic circuits are used with a careful treatment on reliability issues related to charge sharing and noise margin, which has not been treated rigorously in the previous literature. An area-efficient polycell layout style is also introduced for dynamic CMOS circuits. A 4-bit ALU and a 32-bit adder examples are presented to demonstrate the capability of iCOACH.
State capitalism and the rent-seeking conjecture

The notion that state capitalism (an economic system “in which the state functions as the leading economic actor and uses markets primarily for political gain”) is a new form of capitalism emerging in the global arena has been recently advanced by several authors. This paper explores the problem of the nature of this system in the light of these claims to novelty. What are its main features as described by these authors? Is state capitalism distinctive from other forms of capitalism or other types of economic systems? Are we really witnessing the emergence of a new type of economic system? To address such questions the paper starts by trying to place the model of state capitalism within the traditional comparative economic systems framework. The inconclusive result leads to a different approach in which the concept of rent-seeking society is used to underlie the structural similarities between mercantilism, real life socialism and state capitalism. The article argues that the conjecture that what has been labeled “state capitalism” is yet another form of rent-seeking system is both robust and worth further investigating.
Iridium-catalyzed, silyl-directed borylation of nitrogen-containing heterocycles.

Selective methods for the functionalization of indoles and other nitrogen heterocycles would provide access to the core structures of many natural products and pharmaceuticals. Although there are many methods and strategies for the synthesis of substituted indoles or functionalization of the azole ring, strategies for the selective functionalization of the benzo-fused portion of the indole skeleton, particularly the 7-position, are less common. We report a one-pot, iridium-catalyzed, silyl-directed C−H borylation of indoles at the 7-position. This process occurs in high yield with a variety of substituted indoles, and conversions of the 7-borylindole products to 7-aryl-, 7-cinnamyl-, and 7-haloindoles are demonstrated. The Ir-catalyzed, silyl-directed C−H borylation also occurs with several other nitrogen heterocycles, including carbazole, phenothiazines, and tetrahydroquinoline. The utility of this methodology is highlighted by the one-pot synthesis of a member of the pyrrolophenanthridone class of alkal...
Random matrix theory and spectral sum rules for the Dirac operator in QCD

Abstract We construct a random matrix model that, in the large- N limit, reduces to the low-energy limit of the QCD partition function put forward by Leutwyler and Smilga. This equivalence holds for an arbitrary number of flavors and any value of the QCD vacuum angle. In this model, moments of the inverse squares of eigenvalues of the Dirac operator obey sum rules, which we conjecture to be universal. In other words, the validity of the sum rules depends only on the symmetries of the theory but not on its details. To illustrate this point we show that the sum rules hold for an interacting liquid of instantons. The physical interpretations is that the way the thermodynamic limit of the spectral density near zero is approached is universal. However, its value, i.e. the chiral condensate, is not.
The Relationship Between Black Hole Mass and Velocity Dispersion in Seyfert 1 Galaxies

Black hole masses in active galactic nuclei are difficult to measure using conventional dynamical methods but can be determined using the technique of reverberation mapping. However, it is important to verify that the results of these different methods are equivalent. This can be done indirectly, using scaling relations between the black hole and the host galaxy spheroid. For this purpose, we have obtained new measurements of the bulge stellar velocity dispersion, σ*, in Seyfert 1 galaxies. These are used in conjunction with the MBH-σ* relation to validate nuclear black hole masses, MBH, in active galaxies determined through reverberation mapping. We find that Seyfert galaxies follow the same MBH-σ* relation as nonactive galaxies, indicating that reverberation mapping measurements of MBH are consistent with those obtained using other methods. We also reconsider the relationship between bulge absolute magnitude, Mbul, and black hole mass. We find that Seyfert galaxies are offset from nonactive galaxies, but that the deviation can be entirely understood as a difference in bulge luminosity, not black hole mass; Seyfert galaxy hosts are brighter than normal galaxies for a given value of their velocity dispersion, perhaps as a result of younger stellar populations.
Context-sensitive immediate constituent analysis: Context-free languages revisited

The ability of context-sensitive grammars togenerate non-context-free languages is well known. However, phrase-structure rules are often used in both natural and artificial languages, not to generate sentences, but rather toanalyze or parse given putative sentences. Linguistic arguments have been advanced that this is the more fruitful use of CS rules for natural languages, and that, further, it is the purported phrasestructure tree which is presented and analyzed, rather than merely the terminal string itself. In this interpretation, for example the rules {S → AB, A → a/__b, B → b/ a__} “parse” the sentenceab for they “analyze” the tree represented by the labeled bracketing [S[Aa]A[Bb]B]S, even though these rules do not generateab when interpreted as a CS grammar. We shall say that a languageL is parsed by the finite setR of context-sensitive rules ifL consists of the terminal strings of trees analyzed byR. An actual parsing of an artificial language might be obtained, for example, by using a standard “parsing algorithm” for the associated CF grammar (obtained by deleting all contexts from rules) to generate putative trees and then analyzing these trees with the given CS grammar. In this paper, a language is shown to becontext-free if and only if there is a finite set ofcontext-sensitive rules which parse this language; i.e., if and only if there is a collection of trees whose terminal strings are the sentences of this language and a finite set of CS rules which analyze exactly these trees.
Size and Frequency of Defects in Silicon MEMS

Mechanical testing of thin films for MEMS has progressed from a developmental stage to a point where validated techniques are used to study the behavior of devices and materials at a very fine scale. Tensile data covering a range of sizes and test techniques have been analyzed to examine the distribution of defects that would be responsible for the observed fracture strengths. For each sample, a critical defect size was calculated based on a published fracture toughness and a half-circular surface crack fracture toughness model. For polysilicon produced using the SUMMiT V process in the period 1998-1999, the calculated mean defect size was 115 nm. For polysilicon produced using the MUMPS process, the calculated mean defect size was 389 nm.
Asymptotic behavior of dimensions of syzygies

Let R be a commutative noetherian local ring, and M a finitely generated R-module of infinite projective dimension. It is well-known that the depths of the syzygy modules of M eventually stabilize to the depth of R. In this paper, we investigate the conditions under which a similar statement can be made regarding dimension. In particular, we show that if R is equidimensional and the Betti numbers of M are eventually non-decreasing, then the dimension of any sufficiently high syzygy module of M coincides with the dimension of R.
Statistical particle tracking velocimetry using molecular and quantum dot tracer particles

We present a statistical approach to particle tracking velocimetry developed to treat the issues associated with nanometer-sized tracer particles such as fluorescent molecules and quantum dots (QDs) along with theory and experimental results. Extremely small tracers pose problems to traditional tracking methods due to high levels of thermal motion, high levels of intensified camera noise, high drop-in/drop-out rates and, in the case of QDs, fluorescence intermittency (“blinking”). The algorithm presented here compensates for these problems in a statistical manner and determines the physical velocity distributions from measured particle displacement distributions by statistically removing randomly distributed, non-physical tracking events. The algorithm is verified with both numerically simulated particle trackings and experiments using 54 nm diameter fluorescent dextran molecules and 6 and 16 nm diameter QDs.
Nonlinear simulations to optimize magnetic nanoparticle hyperthermia.

Magnetic nanoparticle hyperthermia is an attractive emerging cancer treatment, but the acting microscopic energy deposition mechanisms are not well understood and optimization suffers. We describe several approximate forms for the characteristic time of Neel rotations with varying properties and external influences. We then present stochastic simulations that show agreement between the approximate expressions and the micromagnetic model. The simulations show nonlinear imaginary responses and associated relaxational hysteresis due to the field and frequency dependencies of the magnetization. This suggests that efficient heating is possible by matching fields to particles instead of resorting to maximizing the power of the applied magnetic fields.
Monte Carlo simulation of a near-continuum shock-shock interaction problem

A complex shock interaction is calculated with direct simulation Monte Carlo (DSMC). The calculation is performed for the near-continuum flow produced when an incident shock impinges on the bow shock of a 0.1 in. radius cowl lip for freestream conditions of approximately Mach 15 and 35 km altitude. Solutions are presented both for a full finite-rate chemistry calculation and for a case with chemical reactions suppressed. In each case, both the undisturbed flow about the cowl lip and the full shock interaction flowfields are calculated. Good agreement has been obtained between the no-chemistry simulation of the undisturbed flow and a perfect gas solution obtained with the viscous shock-layer method. Large differences in calculated surface properties when different chemical models are used demonstrate the necessity of adequately representing the chemistry when making surface property predictions. Preliminary grid refinement studies make it possible to estimate the accuracy of the solutions.
Successive cancellation list polar decoder using log-likelihood ratios

Successive cancellation list (SCL) decoding algorithm is a powerful method that can help polar codes achieve excellent error-correcting performance. However, the current SCL algorithm and decoders are based on likelihood or log-likelihood forms, which render high hardware complexity. In this paper, we propose a log-likelihood-ratio (LLR)-based SCL (LLR-SCL) decoding algorithm, which only needs half the computation and storage complexity than the conventional one. Then, based on the proposed algorithm, we develop low-complexity VLSI architectures for LLR-SCL decoders. Analysis results show that the proposed LLR-SCL decoder achieves 50% reduction in hardware and 98% improvement in hardware efficiency.
Analyses of Heat-Pipe Cooled Isothermal Journal Bearings

An isothermal journal bearing that incorporates heat-pipe cooling technology has been developed. The heat pipe can spread frictional heat rapidly along the bearing circumference, resulting in a uniform temperature distribution in the bearing with a low peak temperature and stable transient thermal performance. A numerical model has been developed for the new bearing to facilitate a thorough understanding of its performance as well as an optimal bearing design. The heat pipe in the bearing is modeled as a heat conductor whose effective thermal conductance is determined through the correlation between the numerical results and experimental data. The heat transfer coefficients at bearing boundaries are obtained with the assistance of experimental measurements and calculations using semi-empirical correlations. Good agreement is observed between the analytical and experimental results. Once the analytical model is validated, a parametric study is conducted for the performance of new bearings with different configurations and materials. The analytical results further confirm that the isothermal journal bearing developed has the ability to battle frictional-heat-induced problems, which can significantly benefit both bearing operation and failure prevention.
Evaporation-Combustion Affected by In-Cylinder, Reciprocating Porous Regenerator

An existing in-cylinder thermal regeneration concept for Diesel engines is examined for the roles of the porous insert motion and the fuel injection strategies on the fuel evaporation and combustion and on the engine efficiency. While the heated air emanating from the insert enhances fuel evaporation resulting in a superadiabatic combustion process (thus increasing thermal efficiency), the corresponding increase in the thermal NO x is undesirable. A two-gas-zone and a single-step reaction model are used with a Lagrangian droplet tracking model that allows for filtration by the insert. A thermal efficiency of 53 percent is predicted, compared to 43 percent of the conventional Diesel engines. The optimal regenerative cooling stroke occurs close to the peak flame temperature, thus increasing the superadiabatic flame temperature and the peak pressure, while decreasing the expansion stroke pressure and the pressure drop through the insert. During the regenerative heating stroke, the heated air enhances the droplet evaporation, resulting in a more uniform, premixed combustion and a higher peak pressure, thus a larger mechanical work.
Fused polycyclic nucleophilic carbenes – synthesis, structure, and function

Interest in stable nucleophilic carbenes has grown rapidly since the isolation of the first “bottle-able” example in 1991. Not only has the structural variation of this class of compounds seen an incredible expansion from laboratories around the world, but the chemical reactivity of these compounds has opened many new opportunities for improvements in chemical transformations and invention of new processes. This article reflects our particular interest in fused polycyclic carbenes and focuses on this broad chemical class from both a structural and reactivity perspective.
Comparison of beam-position-transfer functions using circular beam-position monitors

A cylindrical beam-position monitor (BPM) used in many accelerator facilities has four electrodes on which beam-image currents induce bunched-beam signals. These probe-electrode signals are geometrically configured to provide beam-position information about two orthogonal axes. An electronic processor performs a mathematical transfer function (TF) on these BPM-electrode signals to produce output signals whose time-varying amplitude is proportional to the beam's vertical and horizontal position. This paper compares various beam-position TFs using both pencil beams and further discuss how diffuse beams interact with some of these TFs.
Systematic construction of tight-binding Hamiltonians for topological insulators and superconductors

A remarkable discovery in recent years is that there exist various kinds of topological insulators and superconductors characterized by a periodic table according to the system symmetry and dimensionality. To physically realize these peculiar phases and study their properties, a critical step is to construct experimentally relevant Hamiltonians that support these topological phases. We propose a general and systematic method based on the quaternion algebra to construct the tight-binding Hamiltonians for all the three-dimensional topological phases in the periodic table characterized by arbitrary integer topological invariants, which include the spin-singlet and the spin-triplet topological superconductors, the Hopf, and the chiral topological insulators as particular examples. For each class, we calculate the corresponding topological invariants through both geometric analysis and numerical simulation.
Compton scatter imaging in astrophysics

Compton telescopes have been an important tool in gamma ray astronomy, most recently with the COMPTEL instrument on NASA's COMPTON Gamma Ray Observatory (CGRO). Scientific objectives in low/medium energy gamma ray astronomy place highest priority on significant improvement in sensitivity relative to CGRO and ESA's planned INTEGRAL mission. The observational requirements include both discrete and extended sources, and narrow, broad, and continuum spectral features. A high spectral and spatial resolution Compton telescope is the preferred instrument for a future mission. The broad range of scientific objectives that such a mission will address include: mapping radioactivity across the Galaxy (/sup 26/Al, /sup 44/Ti, /sup 60/Fe), detection of several Type Ia supernovae per year (/sup 56/Ni, /sup 56/Co), study nuclear burning in novae (/sup 22/Na, /sup 7/Be, 511 keV), study the accretion of matter onto galactic and massive extra-galactic black holes and clarification of the mechanism for the formation of relativistic jets; provide unique insights into the structure of neutron stars, cosmic gamma ray bursts; and solar flares. A mission to achieve these broad goals should have narrow line sensitivities approaching 10/sup -7/ /spl gamma//cm/sup 2/-s for discrete sources. An energy threshold of /spl sim/250 keV is required to ensure good coverage of the many important astrophysical gamma ray lines from 511 keV to 2 MeV. Angular resolutions much better than 1 degree are required. Detectors which combine state of the art energy resolution (few keV) and spatial resolution (1 mm) are needed. A major breakthrough in background reduction and sensitivity could be realized if tracking low-energy electrons (/spl sim/100 keV) can be achieved.
Be Cautious When Using the FIR Channel Model With the OFDM-Based Communication Systems

Orthogonal frequency-division multiplexing (OFDM) can be used to support high-data-rate transmissions over time-dispersive fading channels. Many OFDM-based communication systems use packet-based transmission, where channel estimation is needed for the detection of information-carrying symbols. The finite impulse response (FIR) channel model is simple and effective for some simulations of channel estimation for the OFDM-based communication systems over the time-dispersive channels; yet, it is only an approximate channel model that cannot be used in the case of accurate channel estimation. Unfortunately, many researchers have overlooked this issue and have been devising channel-estimation algorithms squarely based on the FIR channel model. While the channel estimation results from these algorithms can be impressive for the FIR channels, the algorithms can hardly be applied in real-world applications. This paper explains in detail the reason the FIR channel model is only an approximate channel model for the OFDM-based communication systems, trying to discourage the inappropriate usage of this model, which can lead to fruitless efforts. This paper also presents a realistic channel model for OFDM-based communication systems, which can be used to realistically access the channel parameter-estimation algorithms.
Fourier transform emission spectroscopy of the copper dimer

Abstract The emission spectrum of gas-phase Cu 2 has been observed using a Fourier transform spectrometer. The molecule was produced in a Cu hollow cathode lamp operated with a flow of neon gas. The rotational structure of five bands (2-0, 1-0, 0-0, 0-1, 0-2, and 1-3) belonging to the B 1 Σ u + - X 1 Σ g + system of 63 Cu 2 , and 63 Cu 65 Cu was analyzed, providing improved molecular constants. The equilibrium molecular constants for the X 1 Σ g + state extracted from the observed data are ω e = 266.4594(29) cm −1 , ω e x e = 1.0350(16) cm −1 , and r e = 2.21927(3) A , while the corresponding values for the B 1 Σ u + state are ω e = 246.3170(24) cm −1 , ω e x e = 2.2310(8) cm −1 , and r e = 2.32811(3) A . There is evidence for a systematic global perturbation in the excited B 1 Σ u + state.
Synthesis of substituted carbazoles and β-carbolines by cyclization of diketoindole derivatives☆

Abstract A new route to substituted β -carbolines and carbazoles is described. Diketoindole intermediates, prepared by Friedel–Crafts acylations of 3-substituted indoles, have been converted to 3-hydroxycarbazoles and β -carbolines in good yields, 51–96% and 82–97%, respectively. This method also allows for the formation of 4-substituted β -carbolines. The application of this methodology to the synthesis of the natural products hyellazole and 6-chlorohyellazole is also described.
GEOquery: a bridge between the Gene Expression Omnibus (GEO) and BioConductor

UNLABELLED Microarray technology has become a standard molecular biology tool. Experimental data have been generated on a huge number of organisms, tissue types, treatment conditions and disease states. The Gene Expression Omnibus (Barrett et al., 2005), developed by the National Center for Bioinformatics (NCBI) at the National Institutes of Health is a repository of nearly 140,000 gene expression experiments. The BioConductor project (Gentleman et al., 2004) is an open-source and open-development software project built in the R statistical programming environment (R Development core Team, 2005) for the analysis and comprehension of genomic data. The tools contained in the BioConductor project represent many state-of-the-art methods for the analysis of microarray and genomics data. We have developed a software tool that allows access to the wealth of information within GEO directly from BioConductor, eliminating many the formatting and parsing problems that have made such analyses labor-intensive in the past. The software, called GEOquery, effectively establishes a bridge between GEO and BioConductor. Easy access to GEO data from BioConductor will likely lead to new analyses of GEO data using novel and rigorous statistical and bioinformatic tools. Facilitating analyses and meta-analyses of microarray data will increase the efficiency with which biologically important conclusions can be drawn from published genomic data. AVAILABILITY GEOquery is available as part of the BioConductor project.
Polynomial Matrix Inequality and Semidefinite Representation

Consider a convex set $S=\{x \in \Cal{D}: G(x) \succeq 0\}$ , where G(x) is a symmetric matrix whose every entry is a polynomial or rational function, D ⊆ Rn is a domain on which G(x) is defined, and $G(x) \succeq 0$ means G(x) is positive semidefinite. The set S is called semidefinite representable if it equals the projection of a higher dimensional set that is defined by a linear matrix inequality (LMI). This paper studies sufficient conditions guaranteeing semidefinite representability of S. We prove that S is semidefinite representable in the following cases: (i) D = Rn, G(x) is a matrix polynomial and matrix sos-concave; (ii) D is compact convex, G(x) is a matrix polynomial and strictly matrix concave on D (iii) G(x) is a matrix rational function and q-module matrix concave on D. Explicit constructions of semidefinite representations are given. Some examples are illustrated.
An Improvement to Levenshtein's Upper Bound on the Cardinality of Deletion Correcting Codes

We consider deletion correcting codes over a \(q\) -ary alphabet. It is well known that any code capable of correcting \(s\) deletions can also correct any combination of \(s\) total insertions and deletions. To obtain asymptotic upper bounds on code size, we apply a packing argument to channels that perform different mixtures of insertions and deletions. Even though the set of codes is identical for all of these channels, the bounds that we obtain vary. Prior to this paper, only the bounds corresponding to the all-insertion case and the all-deletion case were known. We recover these as special cases. The bound from the all-deletion case, due to Levenshtein, has been the best known for more than 45 years. Our generalized bound is better than Levenshtein's bound whenever the number of deletions to be corrected is larger than the alphabet size.
Diffraction Effects in Directed Radiation Beams

A number of proposed applications of electromagnetic waves require that the radiation beam maintain a high intensity over an appreciable propagation distance. These applications include, among others, power beaming, advanced radar, laser acceleration of particles, and directed-energy sources. The quest to achieve these objectives has led to a resurgence of research on diffraction theory. We present a survey and critique of the analyses and experimental tests of solutions of the wave equation in connection with so-called diffractionless and other directed radiation beams. The examples discussed include electromagnetic missiles, Bessel beams, electromagnetic directed-energy pulse trains, and electromagnetic bullets.
Development of the LBNL positron emission mammography camera

We present the construction status of the LBNL positron emission mammography (PEM) camera, which utilizes a positron emission tomography (PET) detector module with depth of interaction measurement consisting of 64 LSO crystals (3/spl times/3/spl times/30mm/sup 3/) coupled on one end to a single photomultiplier tube (PMT) and on the opposite end to a 64 pixel array of silicon photodiodes (PDs). The PMT provides an accurate timing pulse, the PDs identify the crystal of interaction, the sum provides a total energy signal, and the PD/(PD+PMT) ratio determines the depth of interaction. We have completed construction of all 42 PEM detector modules. All data acquisition electronics have been completed, fully tested and loaded onto the gantry. We have demonstrated that all functions of the custom IC work using the production rigid-flex boards and data acquisition system. Preliminary detector module characterization and coincidence data have been taken using the production system, including initial images.
Current-based condition monitoring of electrical machines in safety critical applications

The paper presents a complete summary of state-of-the-art techniques for current-based fault monitoring of low voltage permanent magnet synchronous machines commonly used in safety critical applications such as hybrid vehicles and backup generators. This includes detection of stator winding faults, and bearing faults. In addition, a fault tolerant strategy is presented which can be used to operate the machine in a fault tolerant mode even in the presence of the stator turn fault. Experimental results show the efficacy of these methods which allow for use for PM machines even in automotive applications wherein the machine cannot be stopped.
Extreme ultraviolet lithography

Current microlithography used in high-volume integrated circuit manufacturing employs some form of optical projection technology. The most advanced tools use deep-ultraviolet (DUV) radiation having a wavelength of 248 nm and are used to print 250-nm features. These tools will likely be extended for use at the 180-nm generation and perhaps below. New DUV tools using 193-nm radiation are actively under development and are expected to be used for 130-nm generation and perhaps even 100-nm generation. Extending these DUV optical projection tools for manufacturing in the 100-200-nm region will be paced by the development of new high numerical aperture imaging systems and highly complex phase shift masks. For future generations of integrated circuits with minimum feature sizes below 100 nm, 193-nm tools will have great difficulty meeting all manufacturing requirements. This paper describes an alternate optical approach, for sub-100-nm generations, based on extreme ultraviolet radiation at around 13 nm, called extreme ultraviolet lithography (EUVL). This approach uses a laser-produced plasma source of radiation, a reflective mask, and a 4/spl times/ reduction all-reflective imaging system. The technology is currently in the engineering development phase for an alpha machine. This paper reviews its current status and describes the basic modules or building blocks of a generic EUVL exposure tool.
Transition-event durations in one-dimensional activated processes

Despite their importance in activated processes, transition-event durations--which are much shorter than first passage times--have not received a complete theoretical treatment. The authors therefore study the distribution rhob(t) of durations of transition events over a barrier in a one-dimensional system undergoing overdamped Langevin dynamics. The authors show that rhob(t) is determined by a Fokker-Planck equation with absorbing boundary conditions and obtain a number of results, including (i) the analytic form of the asymptotic short-time transient behavior, which is universal and independent of the potential function; (ii) the first nonuniversal correction to the short-time behavior leading to an estimate of a key physical time scale; (iii) following previous work, a recursive formulation for calculating, exactly, all moments of rhob based solely on the potential function-along with approximations for the distribution based on a small number of moments; and (iv) a high-barrier approximation to the long-time (t-->infinity) behavior of rhob(t). The authors also find that the mean event duration does not depend simply on the barrier-top frequency (curvature) but is sensitive to details of the potential. All of the analytic results are confirmed by transition-path-sampling simulations implemented in a novel way. Finally, the authors discuss which aspects of the duration distribution are expected to be general for more complex systems.
The instability of polycrystalline thin films: Experiment and theory

Dense polycrystalline thin films of ZrO2 (3 and 8 mol % Y2O3) were produced by the pyrolysis of zirconium acetate precursor films, which were deposited on single crystal Al2O3 substrates by spin-coating aqueous solutions of zirconium acetate and yttrium nitrate. Dense films were heat treated to encourage grain growth. With grain growth, these films broke into islands of ZrO2 grains. Identical areas were examined after each heat treatment to determine the mechanism that causes the polycrystalline film to uncover the substrate. Two mechanisms were detailed: (a) for a composition which inhibited grain growth and produced a polycrystalline film with very small grains, the smallest grains would disappear to uncover the substrate, and (b) for a composition which did not inhibit grain boundary motion, larger grains grew by enveloping a smaller grain and then developed more spherical surface morphologies, uncovering the substrate at three grain junctions. In both cases, the breakup phenomenon occurred when the average grain size was larger than the film thickness. Thermodynamic calculations show that this breakup lowers the free energy of the system when the grain-size-to-film-thickness ratio exceeds a critical value. These calculations also predict the conditions needed for polycrystalline thin film stability.
Greedoid-Based Noncompensatory Inference

Greedoid languages provide a basis to infer best-fitting noncompensatory decision rules from full-rank conjoint data or partial-rank data such as consider-then-rank, consider-only, or choice data. Potential decision rules include elimination by aspects, acceptance by aspects, lexicographic by features, and a mixed-rule lexicographic by aspects (LBA) that nests the other rules. We provide a dynamic program that makes estimation practical for a moderately large numbers of aspects. We test greedoid methods with applications to SmartPhones (339 respondents, both full-rank and consider-then-rank data) and computers (201 respondents from Lenk et al. 1996). We compare LBA to two compensatory benchmarks: hierarchical Bayes ranked logit (HBRL) and LINMAP. For each benchmark, we consider an unconstrained model and a model constrained so that aspects are truly compensatory. For both data sets, LBA predicts (new task) holdouts at least as well as compensatory methods for the majority of the respondents. LBA's relative predictive ability increases (ranks and choices) if the task is full rank rather than consider then rank. LBA's relative predictive ability does not change if (1) we allow respondents to presort profiles, or (2) we increase the number of profiles in a consider-then-rank task from 16 to 32. We examine trade-offs between effort and accuracy for the type of task and the number of profiles.
Do magnetars glitch? Timing irregularities in anomalous X-ray pulsars

We examine the timing history of several anomalous X-ray pulsars (AXPs), and find that they exhibit spin-down irregularities that are statistically similar to those of radio pulsars. We propose that these irregularities are simply glitches like those of radio pulsars, and fit glitching spin-down solutions to the data available for 1E 2259+586, 1E 1048.1--5937 and 4U 0142+61. The inferred magnitude of the glitches (ΔΟ) is comparable to that exhibited in radio pulsar glitching. With these results, we argue that the three AXPs that we have studied are isolated neutron stars spinning down by magnetic dipole radiation and powered by a combination of cooling, magnetic field decay and magnetospheric particle bombardment.