cssi/SciSciGPT-SciSciNet huggingface dataset:
Control and application of domain wall motion in gadolinium molybdate

Sideways motion of ferroelectric-ferroelastic domain walls in gadolinium and terbium molybdates can be produced with electric fields as low as 200 volts/cm, in relatively defect-free crystals. Crystal mounting and electroding techniques are described that suppress intersections of perpendicular walls, a primary source of crystal failure. Using these techniques, a GMO crystal has been switched successfully over 109 times with no change in physical properties. Polarized light transmitted along the r-axis through a GMO domain wall can be distinguished from light transmitted through surrounding regions of the crystal by spatial and/or polarization filtering. Light exiting the wall can be imaged at 1:1 magnification as a straight, bright line 8-10 microns wide on a dark background. This line can be translated sideways at 250 cm/sec without tilting or bending. Preliminary performance data is given for a prototype GMO-based moving fine line source.
The Dirac Operator of a Commuting d-Tuple

Abstract Given a commuting d-tuple T=(T1, …, Td) of otherwise arbitrary operators on a Hilbert space, there is an associated Dirac operator DT. Significant attributes of the d-tuple are best expressed in terms of DT, including the Taylor spectrum and the notion of Fredholmness. In fact, all properties of T derive from its Dirac operator. We introduce a general notion of Dirac operator (in dimension d=1, 2, …) that is appropriate for multivariable operator theory. We show that every abstract Dirac operator is associated with a commuting d-tuple, and that two Dirac operators are isomorphic iff their associated operator d-tuples are unitarily equivalent. By relating the curvature invariant introduced in a previous paper to the index of a Dirac operator, we establish a stability result for the curvature invariant for pure d -contractions of finite rank. It is shown that for the subcategory of all such T that are (a) Fredholm and and (b) graded, the curvature invariant K(T) is stable under compact perturbations. We do not know if this stability persists when T is Fredholm but ungraded, although there is concrete evidence that it does.
The Busemann–Petty problem in hyperbolic and spherical spaces

Abstract The Busemann–Petty problem asks whether origin-symmetric convex bodies in R n with smaller central hyperplane sections necessarily have smaller n-dimensional volume. It is known that the answer to this problem is affirmative if n ⩽ 4 and negative if n ⩾ 5 . We study this problem in hyperbolic and spherical spaces.
Precision flow-monitoring spectrometer with low noise and high stability

Abstract A Bausch & Lomb Spectronic 20 has been modified to monitor chromatographic columns with high precision and stability. The system employs optical feedback to maintain the source intensity at a constant level. With solvent flowing through the detector, the short-term noise is less than ±0.00005 A.U. (at 100% T ) and drift is ±0.00009 A.U. (at 100% T ) per hour. The utility of the spectrometer is illustrated with the detection of methyl orange eluted from a chromatographic column. In this particular case, 2.3 ng can be detected with 99% confidence.
Recent advances in amino acid N-carboxyanhydrides and synthetic polypeptides: chemistry, self-assembly and biological applications

Polypeptides are fascinating materials with unique properties for various biological materials. We highlight here recent advances in amino acid N-carboxyanhydrides (NCAs) and synthetic polypeptides from the aspects of chemistry, self-assembly and biological applications. New synthetic methodologies, mechanistic studies and optimization of polymerization conditions for the preparation of well-defined novel polypeptides are comprehensively reviewed and evaluated. Functional polypeptides, mostly prepared from novel NCA monomers, with ultra-stable helical conformation, stimuli-sensitive properties, or glycoprotein mimetics are summarized. We also highlight a number of interesting self-assembled structures of polypeptides in solid state and solution, with particular emphasis on those structures other than amphiphilic self-assembly. The biological applications of polypeptides in drug and gene delivery are also reviewed. Future directions and perspectives are discussed in the conclusion.
Au(I)-Catalyzed Efficient Synthesis of Functionalized Bicyclo[3.2.0]heptanes

An efficient Au(I)-catalyzed synthesis of highly strained and functionalized bicyclo[3.2.0]heptanes is developed. Subsequent couplings with various nucleophiles offer additional structural features/complexity. These one-pot, three-component reactions are proposed to proceed via a key 1,3-dipolar cycloaddition between a Au carbenoid-containing carbonyl ylide and ethyl vinyl ether.
A White Light Megaflare on the dM4.5e Star YZ CMi

On UT 2009 January 16, we observed a white light megaflare on the dM4.5e star YZ CMi as part of a long-term spectroscopic flare-monitoring campaign to constrain the spectral shape of optical flare continuum emission. Simultaneous U-band photometric and 3350-9260 A spectroscopic observations were obtained during 1.3 hr of the flare decay. The event persisted for more than 7 hr and at flare peak, the U-band flux was almost 6 mag brighter than in the quiescent state. The properties of this flare mark it as one of the most energetic and longest-lasting white light flares ever to be observed on an isolated low-mass star. We present the U-band flare energetics and a flare continuum analysis. For the first time, we show convincingly with spectra that the shape of the blue continuum from 3350 A to 4800 A can be represented as a sum of two components: a Balmer continuum as predicted by the Allred et al. radiative hydrodynamic flare models and a T{approx} 10,000 K blackbody emission component as suggested by many previous studies of the broadband colors and spectral distributions of flares. The areal coverage of the Balmer continuum and blackbody emission regions vary during the flare decay, withmore » the Balmer continuum emitting region always being significantly ({approx}3-16 times) larger. These data will provide critical constraints for understanding the physics underlying the mysterious blue continuum radiation in stellar flares.« less
Recombinant Human Growth Hormone Modulates Th1 and Th2 Cytokine Response in Burned Mice

ObjectiveTo determine whether growth hormone (GH) influences the production of type 1 T-helper (Th1) and type 2 T-helper (Th2) cytokine responses after burn.Summary Background DataGH has been shown to influence immunoregulation. The authors previously reported improved mortality in burned mice tr
Context-Dependent Transformation of Adult Pancreatic Cells by Oncogenic K-Ras

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal human malignancies. To investigate the cellular origin(s) of this cancer, we determined the effect of PDAC-relevant gene mutations in distinct cell types of the adult pancreas. We show that a subpopulation of Pdx1-expressing cells is susceptible to oncogenic K-Ras-induced transformation without tissue injury, whereas insulin-expressing endocrine cells are completely refractory to transformation under these conditions. However, chronic pancreatic injury can alter their endocrine fate and allow them to serve as the cell of origin for exocrine neoplasia. These results suggest that one mechanism by which inflammation and/or tissue damage can promote neoplasia is by altering the fate of differentiated cells that are normally refractory to oncogenic stimulation.
A prototype circuit-switched multi-wavelength optical metropolitan-area network

A description is given of Rainbow, a prototype optical network based on wavelength-division multiaccess (WDMA). Rainbow supports full-duplex circuit-switched interconnection of up to 32 workstations over a diameter of 25 km, at sustained bit rates of up to 300 Mb/s per connection, allowing a total network capacity of 9.6 Gb/s. Different connections are transparent to each other and may use different protocols and bit rates. >
Imaging a black hole: MAXIM

Abstract With the general acceptance of black holes as real entities the astrophysics community has turned its attention to studying their behavior and properties. Because of the great distance and compact size of the central engine, astronomers are limited to spectroscopic analysis. But to take a picture, or better yet a movie, of the black hole in silhouette against its accretion disk would be a triumph of exploration and scientific inquiry. Probing to the event horizon is best accomplished in the X-ray band, where material primarily radiates in the last orbits before its final plunge. Not only will the signal be bright and minimally confused in the X-ray, but the size of the required interferometer drops dramatically. We describe MAXIM, the Micro-Arcsecond X-ray Imaging Mission, which is now being studied and developed by NASA. We will explain the preliminary mission concept which will use currently existing technology to achieve spatial resolution one million times higher than that of the Hubble Space Telescope and capture the image of an event horizon in a nearby Active Galactic Nucleus. We will also describe the MAXIM Pathfinder. Designed as a stepping stone at resolution of 100 micro-arcseconds, it will demonstrate the techniques of X-ray interferometry and perform groundbreaking science like resolving the coronae of the nearby stars.
Applications of scanning laser source technique for detection of surface-breaking defects

A new laser ultrasonic approach, the Scanning Laser Source (SLS) technique, is presented for detection of small surface-breaking defects. In this approach we do not monitor the interaction of a generated ultrasonic wave with a flaw, as in the case of traditional pitch-catch or pulse-echo methods, but rather monitor the changes in the laser generated ultrasonic signal as the source is scanned over a defect. Changes in the amplitude and frequency content of the laser-generated ultrasound are observed resulting from the changed conditions under which the ultrasound is generated over areas without and with a surface- breaking crack. These changes are quite readily detectable using existing ultrasonic detectors. The SLS system includes a fiberized portable Q-switched YAG:Nd laser, which can be combined with either convention PZT transducers or laser interferometers. Results are presented for detection fo small EDM notches and fatigue cracks on flat and curved specimens and thin plates including real structures such as an aircraft turbine disk. It is shown that the SLS technique has several advantages over the conventional pitch-catch approach, including: (i) enhanced signal-to-noise performance, (ii) detection of defects with size smaller than the ultrasonic wavelength (at least 0.125 mm length and 0.06 mm depth), (iii) ability to detect defects of various orientations with respect to the scanning direction, (iv) inspection of surfaces with complex geometry such as bore holes and turbine disk slots.
Microwave, infrared and Raman spectra, conformational stability and vibrational assignment of methoxyflurane

Abstract The low resolution microwave spectrum of methoxyflurane, CHCl2CF2OCH3, has been recorded from 26.5 to 39.0 GHz. From the spacing of the major transitions it is shown that the value of 2036 MHz for B + C is consistent with the trans-trans or gauche-trans conformers where the first term (trans or gauche) refers to the internal rotation around the C-C bond. The infrared (40–3500 cm−1) and the Raman (20–3500 cm−1) spectra have been recorded for gaseous and solid methoxyflurane. Additionally, the Raman spectrum of the liquid has been obtained and qualitative depolarization ratios measured. From these data it is shown that the most stable form in the fluid phases at ambient temperature is the gauche-trans conformer but the trans-trans form is the most stable in the solid state. A complete vibrational analysis based on infrared band contours, depolarization values and group frequencies is proposed for this conformer. From the analysis of the low frequency vibrational data, values of some of the barriers to internal rotation are estimated. These results are compared to some similar quantities for some corresponding molecules.
Alzheimer's disease: A hypothesis on pathogenesis.

Alzheimer’s disease (AD) is the major cause of dementia. It is a systemic disorder whose major manifestations are in the brain. AD cases can be categorized into two groups on the basis of the age of onset-before or after about age 60. The majority of cases, 90–95 percent, are in the late onset category. Early onset cases are largely, if not all, familial (FAD). These are caused by mutations in the genes for the amyloid precursor protein (APP), presenilin 1 (PS1), and presenilin 2 (PS2). In contrast late onset cases are mainly sporadic. The disorder is characterized by intraneuronal fibrillary tangles, plaques, and cell loss. The brain lesions in both early and late-onset AD are the same, and in the same distribution pattern, as those seen in individuals with Down’s syndrome (DS) and in smaller numbers in normal older individuals. Extensive studies of AD have yet to result in a generally accepted hypothesis on the pathogenesis of the disorder. Major emphasis has been placed on the role of amyloid, the neurotoxin formed by the action of free radicals on preamyloid. The observation that AD lesions are frequently present in normal older individuals prompted the hypothesis that AD is the result of faster than normal aging of the neurons associated with it. This hypothesis provides plausible explanations for FAD and AD. FAD is associated with mutations in APP, PS1, and PS2. These substances, along with their normal counterparts, undergo proteolytic processing in the endoplasmic reticulum (ER). The mutated compounds, aside from increasing the ratio of βA42 to βA40, may down-regulate the calcium buffering activity of the ER in a manner akin to one or more of the many compounds known to do so. Decreases in the ER calcium pool would cause compensatory increases in other calcium pools, particularly in mitochondria. Increases in mitochondrial calcium levels are associated with enhanced formation of superoxide radical formation, and hence of the rate of aging. SAD may be caused by nuclear and/or mitochondrial DNA mutations beginning early in life that enhance mitochondrial superoxide radical formation in the neurons associated with the disorder. The above explanations for FAD and AD are suggestive of measures to prevent and for treatment.
Hardware Demonstration of Flexible Beam Control

An experiment employing a pinned-free flexible beam has been constructed to demonstrate and verify several facets of the control of flexible structures. The desired features of the experiment are to demonstrate active shape control, active dynamic control, adaptive control, various control law design approaches, and associated hardware requirements and mechanization difficulties. This paper contains the analytical work performed in support of the facility development, the final design specifications, control law synthesis, and some preliminary results.
Total synthesis of the ramoplanin A2 and ramoplanose aglycon

A convergent total synthesis of the ramoplanin A2 and ramoplanose aglycon is disclosed. Three key subunits composed of residues 3−9 (heptapeptide 15), pentadepsipeptide 26, and pentapeptide 34 (residues 10−14) were prepared, sequentially coupled, and cyclized to provide the 49-membered depsipeptide core of the aglycon. Key to the preparation of the pentadepsipeptide 26 incorporating the backbone ester was the asymmetric synthesis of an orthogonally protected l-threo-β-hydroxyasparagine and the development of effective and near-racemization free conditions for esterification of its hindered alcohol (EDCI, DMAP, 0 °C). The coupling sites were chosen to maximize the convergency of the synthesis including that of the three subunits, to prevent late stage racemization of carboxylate-activated phenylglycine-derived residues, and to enlist β-sheet preorganization of an acyclic macrocyclization substrate for 49-membered ring closure. As such, macrocyclization at the chosen Phe9-d-Orn10 site may benefit from both ...
Distributed Throughput-Optimal Scheduling in Ad Hoc Wireless Networks

In this paper, we propose a distributed throughput-optimal ad hoc wireless network scheduling algorithm, which is motivated by the celebrated simplex algorithm for solving linear programming (LP) problems. The scheduler stores a sparse set of basic schedules, and chooses the max-weight basic schedule for transmission in each time slot. At the same time, the scheduler tries to update the set of basic schedules by searching for a new basic schedule in a throughput increasing direction. We show that both of the above procedures can be achieved in a distributed manner. Specifically, we propose an average consensus based link contending algorithm to implement the distributed max weight scheduling. Further, we show that the basic schedule update can be implemented using CSMA mechanisms, which is similar to the one proposed by Jiang et al. Compared to the optimal distributed scheduler, where schedules change in a random walk fashion, our algorithm has a better delay performance by achieving faster schedule transitions in the steady state. The performance of the algorithm is finally confirmed by simulation results.
Uniform Macroporous Ceramics and Plastics by Emulsion Templating

More-over, the ability to control pore size and uniformity couldproduce improved filters, membrane supports, catalytic ma-terials, and adsorbents. Nevertheless, until very recently,there has been no general method available for producingsuch materials. The primary problem has been controllingthe pore size distribution; existing techniques result in anextremely broad distribution of pore sizes.
Chiral melting of the Si(113) (3 × 1) reconstruction

Abstract We report the results of synchrotron X-ray scattering studies of the disordering of the Si(113) (3 × 1) reconstruction. A continuous commensurate—solid to incommensurate—fluid transformation at T c = 950 ± 40 K is observed. At the transformation, the reconstructed layer becomes uniaxially incommensurate along the cubic (11¯0) ( x -direction). It remains commensurate along the (332¯) ( y -direction). Critical scattering shows power-law behavior over nearly two decades of reduced temperature with exponents β¯ for the incommensurability ( ɛ ), t x = 0.65 ± 0.07 for the inverse correlation length in the incommensurate direction ( ϰ x ), v y = 1.06 ± 0.07 for the inverse correlation length in the commensurate direction ( ϰ y ), and γ = 1.56 ± 0.13 for the susceptibility ( χ ). Below T c the variation of the square of the order parameter, proportional to the peak intensity at the commensurate position ( I 0 ), varies with an exponent 2 β = 0.22 ± 0.04. It is noteworthy that the correlation lengths in the disordered phase scale anisotropically, i.e. v x ≠ v y , and that the collected exponents do not conform to those of any previously measured universality class. Two universal constants of the transformation have also been measured. The ratio of the incommensurability and the inverse correlation length along the incommensurate direction in the disordered phase is found to be independent of temperature, i.e. β¯, consistent with predictions for a new two-dimensional chiral melting universality class, and to have the value w 0 = 1.6 ± 0.2. Also, the hyperscaling ratio R s = χϰ x ϰ y / I 0 V r , where V r is the two-dimensional resolution volume, is independent of the reduced temperature, consistent with the derived hyperscaling relationship v x + v y = γ + 2 β . According to the hypothesis of two-scale-factor universality, R s is a universal constant, which we find takes the value R s = 0.07 ± 0.03. These results are discussed in the context of proposed phase diagrams of two-dimensional threefold-degenerate uniaxial overlayers where the chirality, or difference in free energy of light and heavy domain walls, is varied. A comparison is made to recent LEED measurements of the (3 × 1)-to-disordered transformations of Si and Ge.
Stochastic renormalization group in percolation: I. fluctuations and crossover

Abstract A generalization of the Renormalization Group, which describes order-parameter fluctuations in finite systems, is developed in the specific context of percolation. This “Stochastic Renormalization Group” (SRG) expresses statistical self-similarity through a non-stationary branching process. The SRG provides a theoretical basis for analytical or numerical approximations, both at and away from criticality, whenever the correlation length is much larger than the lattice spacing (regardless of the system size). For example, the SRG predicts order-parameter distributions and finite-size scaling functions for the complete crossover between phases. For percolation, the simplest SRG describes structural quantities conditional on spanning, such as the total cluster mass or the minimum chemical distance between two boundaries. In these cases, the Central Limit Theorem (for independent random variables) holds at the stable, off-critical fixed points, while a “Fractal Central Limit Theorem” (describing long-range correlations) holds at the unstable, critical fixed point. This first part of a series of articles explains these basic concepts and a general theory of crossover. Subsequent parts will focus on limit theorems and comparisons of small-cell SRG approximations with simulation results.
SigSag: Iterative Detection Through Soft Message-Passing

The multiple-access framework of ZigZag decoding (Gollakota and Katabi 2008) is a useful technique for combating interference via multiple repeated transmissions, and is known to be compatible with distributed random access protocols. However, in the presence of noise this type of decoding can magnify errors, particularly when packet sizes are large. We show that ZigZag decoding can be seen as an instance of belief propagation in the high signal-to-noise ratio (SNR) limit. Building on this observation, we present a simple soft-decoding version, called SigSag, that improves performance. We show that for two users, collisions result in a cycle-free factor graph that can be optimally decoded via belief propagation. For collisions between more than two users, we show that if a simple bit-permutation is used then the graph is locally tree-like with high probability, and hence belief propagation is near-optimal. Further, we introduce the joint channel-collision decoding which decodes the collided packets while the packets are coded by an LDPC code. Through simulations we show that our scheme performs better than coordinated collision-free time division multiple access (TDMA) and the ZigZag decoder. Furthermore, we investigate the performance of the joint channel-collision decoder in different scenarios and show that it performs better than TDMA and ZigZag decoder accompanied by sum-product decoding.
An efficient synthesis of highly functionalized chiral lactams

A new method was developed to synthesize highly functionalized lactams via a one pot reductive amination/lactam formation reaction. This methodology is amenable for parallel synthesis and was used to prepare a large number of lactam analogs in a library format with good ee (de) retention.
α,β-Unsaturated β-Silyl Imide Substrates for Catalytic, Enantioselective Conjugate Additions: A Total Synthesis of (+)-Lactacystin and the Discovery of a New Proteasome Inhibitor

Chiral (salen)Al mu-oxo dimer 1 catalyzes the highly enantioselective conjugate addition of carbon-centered nucleophiles to alpha,beta-unsaturated silyl imides. Allyldimethylsilane-substituted imide 4 was identified as an optimal substrate, undergoing addition reactions with a variety of nitrile nucleophiles in high yield and enantiomeric excess. The silicon-containing products are synthetically useful chiral building blocks, as demonstrated by their application to an enantioselective total synthesis of the potent proteasome inhibitor (+)-lactacystin (2). Elaboration of lactam 5a to the natural product was effected in 12 steps and in 11% overall yield and proceeded through an unusual spiro beta-lactone intermediate (11). This compound was found to inhibit the chymotrypsin-like site of the 26S proteasome at similar levels to known inhibitor clasto-lactacystin beta-lactone (omuralide).
Soft supersymmetry breaking induced by higher-derivative supergravitation in the electroweak standard model

Abstract We show how spontaneous supersymmetry breaking in the vacuum state of higher-derivative supergravity is transmitted, as explicit soft supersymmetry-breaking terms, to the effective Lagrangian of the standard electroweak model. The general structure of the soft supersymmetry breaking terms is presented and a new scenario for understanding the gauge hierarchy problem, based on the functional form of these terms, is discussed.
Lattice calculation of the lowest order hadronic contribution to the muon anomalous magnetic moment: an update with Kogut-Susskind fermions

Abstract I present a preliminary calculation of the hadronic vacuum polarization for 2+1 flavors of improved Kogut-Susskind quarks by utilizing a set of gauge configurations recently generated by the MILC collaboration. The polarization function Π(q2) is then used to calculate the lowest order (in αQED) hadronic contribution to the muon anomalous magnetic moment.
A Novel Synthesis of Squaric Acid Esters

Abstract A new procedure for the synthesis of the benzylic ester of the squaric acid is described. A first example of the reaction silyl ‘enol ether’ of the squaric acid with an electrophile in the presence of a fluoride source to give an O-alkylated product is described.
NMR studies of strong hydrogen bonds in enzymes and in a model compound

Abstract Hydrogen bond lengths on enzymes have been derived with high precision (≤±0.05 A ) from both the proton chemical shifts (δ) and the fractionation factors (φ) of the proton involved and were compared with those obtained from protein X-ray crystallography. Hydrogen bond lengths derived from proton chemical shifts were obtained from a correlation of 59 O–H⋯O hydrogen bond lengths, measured by small molecule high resolution X-ray crystallography, with chemical shifts determined by solid-state NMR in the same crystals [A. McDermott, C.F. Ridenour, Encyclopedia of NMR, Wiley, Sussex, England, 1996, 3820pp]. Hydrogen bond lengths were independently obtained from fractionation factors which yield distances between the two proton wells in quartic double minimum potential functions [M.M. Kreevoy, T.M. Liang, J. Am. Chem. Soc. 102 (1980) 3315]. The high precision hydrogen bond lengths derived from their corresponding NMR-measured proton chemical shifts and fractionation factors agree well with each other and with those reported in protein X-ray structures within the larger errors (±0.2–0.8 A) in lengths obtained by protein X-ray crystallography. The increased precision in measurements of hydrogen bond lengths by NMR has provided insight into the contributions of short, strong hydrogen bonds to catalysis for several enzymes including ketosteroid isomerase, triosephosphate isomerase, and serine proteases. The O–H⋯O hydrogen bond length derived from the proton chemical shift in a model dihydroxy-naphthalene compound in aqueous solution agreed well with lengths of such hydrogen bonds determined by high resolution, small molecule X-ray diffraction.
Diastereo- and enantioselective copper-catalyzed intramolecular carboamination of alkenes for the synthesis of hexahydro-1H-benz[f]indoles.

A new method for the enantioselective synthesis of hexahydro-1H-benz[f]indoles is described. This copper-catalyzed enantioselective intramolecular alkene carboamination process can install vicinal tertiary and quaternary carbon stereocenters with high levels of diastereo- and enantioselectivity. The C−C bond-forming component of the reaction constitutes a C−H functionalization and no electronic activation of the aryl ring that undergoes addition is required. A known 5-HT1A receptor antagonist was synthesized efficiently using this method.
Four-wave mixing and phase conjugation in plasmas using ionization nonlinearities.

Four-wave mixing in plasmas using ponderomotive and thermal nonlinearities has been extensively studied. Plasmas have received considerable attention since they become more efficient four-wave-mixing and phase-conjugation media at longer wavelengths (far infrared, 10 \ensuremath{\mu}m, to radio wave, 10 m). In this paper, the prospect of using an ionization nonlinearity in weakly ionized plasmas for degenerate four-wave mixing and phase conjugation is discussed. Like the thermal pressure nonlinearity, the ionization nonlinearity results from the heating of the plasma by the beat wave. However, as the local temperature increases, more neutral species are ionized by electron-impact ionization to form a beat-wave grating structure; instead of pushing the electrons into a grating structure (as with the thermal and ponderomotive nonlinearities), the electron density grating is created directly by ionization. Numerical estimates of the phase-conjugate reflectivity indicate reflectivities in the range of ${10}^{\mathrm{\ensuremath{-}}4--}$${10}^{\mathrm{\ensuremath{-}}3}$ are possible in a weakly ionized steady-state gas-discharge plasma. The reflectivity is limited to this range due to the onset of an ionization instability (striations). Larger reflectivities may be possible for pulsed plasma sources.
A novel approach to linear model simplification

New techniques for the model simplification problem are presented. If the given system is expressed by a high-order transfer function, the technique is to expand the function into a continued fraction and then ignore some quotients. If the system is in the state equations form, the method is realized by partitioning the matrix and discarding some parts. The new approach not only offers a simple procedure and a good approximation but also gives a unified viewpoint of the general analysis of linear systems.
Connectivity properties of dimension level sets

This paper initiates the study of sets in Euclidean spaces ℝn (n ≥ 2) that are defined in terms of the dimensions of their elements. Specifically, given an interval I ⊆ [0, n ], we are interested in the connectivity properties of the set DIMI, consisting of all points in ℝn whose (constructive Hausdorff) dimensions lie in I, and of its dual DIMIstr, consisting of all points whose strong (constructive packing) dimensions lie in I. If I is [0, 1) or (n – 1, n ], it is easy to see that the sets DIMI and DIMIstr are totally disconnected. In contrast, we show that if I is [0, 1] or [n – 1, n ], then the sets DIMI and DIMIstr are path-connected. Our proof of this fact uses geometric properties of Kolmogorov complexity in Euclidean spaces. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
Extended operation of flying capacitor multilevel inverters

Recent research in flying capacitor multilevel inverters (FCMIs) has shown that the number of voltage levels can be extended by changing the ratio of the capacitor voltages. For the three-cell FCMI, four levels of operation are expected if the traditional ratio of the capacitor voltages is 1:2:3. However, by altering the ratio, the inverter can operate as a five-, six-, seven-, or eight-level inverter. According to previous research, the eight-level case is referred to as maximally distended (or full binary combination schema) since it utilizes all possible transistor switching states. However, this case does not have enough per-phase redundancy to ensure capacitor voltage balancing under all modes of operation. In this paper, redundancy involving all phases is used along with per-phase redundancy to improve capacitor voltage balancing. It is shown that the four- and five-level cases are suitable for motor drive operation and can maintain capacitor voltage balance under a wide range of power factors and modulation indices. The six-, seven-, and eight-level cases are suitable for reactive power transfer in applications such as static var compensation. Simulation and laboratory measurements verify the proposed joint-phase redundancy control.
Derivatives and constraints in chaotic flows: asymptotic behaviour and a numerical method

In a smooth flow, the leading-order response of trajectories to infinitesimal perturbations in their initial conditions is described by the finite-time Lyapunov exponents and associated characteristic directions of stretching. We give a description of the second-order response to perturbations in terms of Lagrangian derivatives of the exponents and characteristic directions. These derivatives are related to generalised Lyapunov exponents, which describe deformations of phase space elements beyond ellipsoidal. When the flow is chaotic, care must be taken in evaluating the derivatives because of the exponential discrepancy in scale along the different characteristic directions. Two matrix decomposition methods are used to isolate the directions of stretching, the first appropriate in finding the asymptotic behaviour of the derivatives analytically, the second better suited to numerical evaluation. The derivatives are shown to satisfy differential constraints that are realised with exponential accuracy in time. With a suitable reinterpretation, the results of the paper are shown to apply to the Eulerian framework as well.
Geologic occurrence of zeolites and some associated minerals

The principal geologic settings of zeolites are (1) saline, alkaline lakes, (2) saline, alkaline soils, (3) deep-sea sediments, (4) low-temperature open hydrologic systems, (5) burial diagenesis, and (6) hydrothermal-geothermal systems. Volcanic ash layers alter rapidly to zeolites in saline, alkaline lakes, and relatively pure deposits can be formed. Silicic volcanic glass is altered slowly, and principally to smectite, in deposits of moderately saline, nonalkaline lakes, as demonstrated in sediments of Searles Lake, California. Vitric tuffs in saline, alkaline playa-lake complexes are characteristically zoned from an outer fresh-water zone with unaltered glass or glass altered to smectite, an inner saline zone with zeolites, and an innermost highly saline zone with analcime and/or alkali feldspar, most commonly K-feldspar. Large-scale zoning of saline, alkaline type is exhibited by the Upper Jurassic Morrison Formation in the San Juan Basin, New Mexico and Arizona. Deep-sea sediments contain large volumes of clinoptilolite and phillipsite. The phillipsite predominates in Miocene and younger sediments and clinoptilolite in older sediments, possibly because clinoptilolite was favored in pre-Miocene sediments by more siliceous pore waters. Hydrolysis by ground water in open hydrologic systems can transform ash layers to bentonite or to zeolite-rich deposits. Temperature is the principal control on zeolite assemblages in burial-diagenetic and hydrothermal-geothermal systems. Igneous analcime has been documented in the Colima Volcanic Complex of Mexico.
Influence of natural convection on mass transfer rates for the electrolysis of ferricyanide ions

Abstract Results are presented for local and overall current densities at a cylindrical cathode in an unsupported solution of potassium ferro- and ferricyanide under conditions that mass transfer is controlling. The applicability of laminar boundary layer theory to describe natural convection is tested by examining the circumferential variation of the local mass transfer rate. At large electrolyte concentrations two types of instabilities are observed. One involves unsteady flow at the rear of the cylinder and the other both at the front and the rear. The magnitude of current densities at the cathode is predicted within 6 per cent by laminar natural convection theory if the density difference at the cathode is calculated by the appropriate procedures developed by Wilke, Eisenberg and Tobias.
Testing a model for the puzzling spin 0 mesons

After a brief historical discussion of meson quantum numbers, we examin the possibility of additional internal meson structure. Experimental tests of this structure using the semi-leptonic decays of the $D_s^+n$(1968) meson are discussed.
Automatic Pipelining From Transactional Datapath Specifications

This paper presents a transactional specification framework (T-spec) for describing a datapath and the tool T-piper to synthesize automatically an in-order pipelined implementation with arbitrary user-specified pipeline-stage boundaries. T-spec abstractly views a datapath as executing one transaction at a time, computing the next system states based on the current ones. The synthesized pipeline maintains this semantics, yet allows concurrent execution of multiple overlapped transactions in different pipeline stages, where each stage performs a part of the next-state computation of each transaction. T-spec makes the state reading and writing events in a datapath explicit to enable T-piper to perform exact read-after-write (RAW) hazard analysis between the overlapped transactions. T-piper can automatically generate the pipeline control not only to ensure the correctness of the pipelined executions but also to minimize (using forwarding and speculation) the performance loss due to pipeline stalls in the presence of RAW dependencies. This paper reports design case studies applying T-spec and T-piper to reduced instruction set computing and complex instruction set computing processor pipeline development. In the latter, we report the results from a rapid design space exploration of 60 generated x86-subset pipelines, varying in pipeline depth, forwarding, and speculative execution, all starting from a single T-spec.
A novel fluorinated tryptamine with highly potent serotonin 5-HT1A receptor agonist properties

Synthesis and biological evaluation of a novel fluorinated tryptamine analogue are described. This new compound 1-(4-fluoro-5-methoxyindol-3-yl)pyrrolidine (2) was found to be a potent serotonin 5-HT1A agonist.
Acoustic Shielding for a Model Scale Counter-rotation Open Rotor

The noise shielding benefit of installing an open rotor above a simplified wing or tail is explored experimentally. The test results provide both a benchmark data set for validating shielding prediction tools and an opportunity for a system level evaluation of the noise reduction potential of propulsion noise shielding by an airframe component. A short barrier near the open rotor was found to provide up to 8.5 dB of attenuation at some directivity angles, with tonal sound particularly well shielded. Predictions from two simple shielding theories were found to overestimate the shielding benefit. Nomenclature f Frequency, Hz Bf Number of blades on the front rotor Ba Number of blades on the aft rotor Nf Front rotor shaft rotation frequency, Hz Na Aft rotor shaft rotation frequency, Hz ps Complex acoustic pressure when the acoustic shield is in place, Pa pu Complex acoustic pressure in the unshielded configuration, Pa ˜ ps Measured RMS acoustic pressure spectrum when the acoustic shield is in place, Pa ˜ pu Measured RMS acoustic pressure spectrum in the unshielded configuration, Pa SO Propulsor Shaft Order, 2f/(Nf + Na) �SPL Decibel reduction in sound pressure level due to the acoustic shield
Chemical Vapor Deposition of Boron Nitride

Thermodynamics and kinetics of boron nitride deposition from gas mixtures were studied in the temperature range 850 to 1050°C at pressures between 1.1 and 3.5 Torr. A wide range of deposition rates, as high as 1 μm/min, were measured. The rate of depositon was controlled by an interface reaction with an activation energy of . The deposition rate constant essentially was independent of the partial pressure of and showed a close to first‐order dependence on the partial pressure of . The rate‐limiting step of the interface reaction may be the dissociative adsorption of onto the substrate surface. The deposited BN was of theoretical density, turbostratic structure, and contained about 12 atomic percent oxygen.
Multiscale adaptive smoothing models for the hemodynamic response function in fMRI

In the event-related functional magnetic resonance imaging (fMRI) data analysis, there is an extensive interest in accurately and robustly estimating the hemodynamic response function (HRF) and its associated statistics (e.g., the magnitude and duration of the activation). Most methods to date are developed in the time domain and they have utilized almost exclusively the temporal information of fMRI data without accounting for the spatial information. The aim of this paper is to develop a multiscale adaptive smoothing model (MASM) in the frequency domain by integrating the spatial and temporal information to adaptively and accurately estimate HRFs pertaining to each stimulus sequence across all voxels in a three-dimensional (3D) volume. We use two sets of simulation studies and a real data set to examine the finite sample performance of MASM in estimating HRFs. Our real and simulated data analyses confirm that MASM outperforms several other state-of-art methods, such as the smooth finite impulse response (sFIR) model.
Advection-Dominated Accretion and the Spectral States of Black Hole X-Ray Binaries: Application to Nova Muscae 1991

Black hole X-ray binaries (BHXBs) are known to display five distinct spectral states. In order of increasing luminosity these are the quiescent state, low state, intermediate state, high state, and very high state. We present a self-consistent model of accretion flows around black holes that unifies all of these states except the very high state. The model is an extension of the following paradigm, which has been applied successfully to the quiescent state. The accretion flow consists of two zones, an inner advection-dominated accretion flow (ADAF) that extends from the black hole horizon to a transition radius rtr, and an outer thin accretion disk that is present beyond rtr. Above the disk is a hot corona, which is a continuation of the inner ADAF. The model consistently treats the dynamics of the accreting gas, the thermal balance of the ions and electrons in the two-temperature ADAF and corona, and the radiation processes that produce the observed spectrum. At low mass accretion rates, 0.01 (in Eddington units), the inner ADAF zone in the model radiates extremely inefficiently, and the outer thin disk is restricted to large radii (rtr ~ 102-104, in Schwarzschild units). The luminosity therefore is low, and this configuration is identified with the quiescent state. For 0.01 and up to a critical value crit${r crit}$ --> ~0.08, the radiative efficiency of the ADAF increases rapidly and the system becomes fairly luminous. The spectrum is very hard and peaks around 100 keV. This is the low state. The exact value of crit${r crit}$ --> depends on the viscosity parameter α (crit${r crit}$ --> ~1.3α -->2; the paper assumes α = 0.25). For values of > crit${r crit}$ --> and up to a second critical value about 10% higher, the ADAF progressively shrinks in size, the transition radius decreases, and the X-ray spectrum changes continuously from hard to soft. We identify this stage with the intermediate state. Finally, when is sufficiently large, the inner ADAF zone disappears altogether and the thin accretion disk extends down to the marginally stable orbit. The spectrum is dominated by an ultrasoft component with a weak hard tail. This is the high state. Model spectra calculated with this unified scenario agree well with observations of the quiescent, low, intermediate, and high states. Moreover, the model provides a natural explanation for the low state to high state transition in BHXBs. We also make a tentative proposal for the very high state, but this aspect of the model is less secure. An important feature of the model is that it is essentially parameter free. We test the model against observations of the soft X-ray transient Nova Muscae during its 1991 outburst. The model reproduces the observed light curves and spectra surprisingly well and makes a number of predictions that can be tested by observations of other BHXBs.
Pagination: it's what you say, not how long it takes to say it

Pagination the process of determining where to break an article across pages in a multi-article layout is a common layout challenge for most commercially printed newspapers and magazines. To date, no one has created an algorithm that determines a minimal pagination break point based on the content of the article. Existing approaches for automatic multi-article layout focus exclusively on maximizing content (number of articles) and optimizing aesthetic presentation (e.g., spacing between articles). However, disregarding the semantic information within the article can lead to overly aggressive cutting, thereby eliminating key content and potentially confusing the reader, or setting too generous of a break point, thereby leaving in superfluous content and making automatic layout more difficult. This is one of the remaining challenges on the path from manual layouts to fully automated processes that still ensure article content quality. In this work, we present a new approach to calculating a document minimal break point for the task of pagination. Our approach uses a statistical language model to predict minimal break points based on the semantic content of an article. We then compare 4 novel candidate approaches, and 4 baselines (currently in use by layout algorithms). Results from this experiment show that one of our approaches strongly outperforms the baselines and alternatives. Results from a second study suggest that humans are not able to agree on a single "best" break point. Therefore, this work shows that a semantic-based lower bound break point prediction is necessary for ideal automated document synthesis within a real-world context.
Blazar flaring rates measured with GLAST

Abstract We derive the minimum observing time scales to detect a blazar at a given flux level with the LAT on the Gamma-ray Large Area Space Telescope (GLAST) in the scanning and pointing modes. Based upon Phase 1 observations with EGRET, we predict the GLAST detection rate of blazar flares at different flux levels. With some uncertainty given the poor statistics of bright blazars, we predict that a blazar flare with integral flux ≳200×10−8 photons (>100 MeV) cm−2 s−1, which are the best candidates for Target of Opportunity pointings and extensive temporal and spectral studies, should occur every few days.
Which is the more ‘evolved’ in modern humans, the hand or the foot?

I been involved in human evolution research since the 1960s, and within that 40-year period the fossil evidence for human evolution has burgeoned. Before the 1960s there was no significant fossil evidence for human evolution from East Africa, but that has all changed. East Africa now provides fossil evidence that stretches from 6 million-year-old possible early human ancestors to the earliest evidence for modern humans that date back to a little under 200 hundred thousand years ago. Between these extremes lie the fossil remains of creatures their discoverers gave unofficial names to, such as ‘Nutcracker Man’ and ‘Handy Man’ from Olduvai Gorge in Tanzania, and even individual fossils, such as ‘Lucy’ from Hadar in Ethiopia, have found their way onto the front pages of the National Geographic magazine and Time. Yet despite this dramatic new evidence, I think a good case can be made that the most important contribution to increasing our understanding of human evolution in the last 40 years has come not from the discovery of fossil evidence, but from comparative and molecular biology. Biochemistry and subsequently molecular biology have provided ways to compare types of animals by looking at their constituent molecules, including DNA, as opposed to the bones and soft tissues of organisms, and these lines of evidence have helped researchers resolve the branching pattern of Tree of Life (TOL). The close gross morphological similarity between modern humans and the great apes (chimpanzees, bonobos, gorillas and orangutans) had been noted close on a 150 years ago by Huxley [1]. However, despite evidence that modern human and chimpanzee haemoglobin and albumin were virtually indistinguishable [2,3], the differences between modern humans and the great apes were always regarded as being substantially greater that the differences among the great apes. This view was reflected