cssi/SciSciGPT-SciSciNet huggingface dataset:
Magnetic penetration depth in unconventional superconductors

This topical review summarizes various features of magnetic penetration depth in unconventional superconductors. Precise measurements of the penetration depth as a function of temperature, magnetic field and crystal orientation can provide detailed information about the pairing state. Examples are given of unconventional pairing in hole- and electron-doped cuprates, organic and heavy fermion superconductors. The ability to apply an external magnetic field adds a new dimension to measurements of penetration depth. We discuss how field-dependent measurements can be used to study surface Andreev bound states, nonlinear Meissner effects, magnetic impurities, magnetic ordering, proximity effects and vortex motion. We also discuss how measurements of penetration depth as a function of orientation can be used to explore superconductors with more than one gap and with anisotropic gaps. Details relevant to the analysis of penetration depth data in anisotropic samples are also discussed.
Bourdieu 1993: A Case Study in Scientific Consecration

Drawing on archival materials and personal testimonies, I reconstruct the conditions under which Bourdieu came to receive the Gold Medal of the National Center for Scientific Research, France’s highest science prize, in 1993 as a signal case study of the existential predicament and institutional trappings of scholarly consecration. Bourdieu’s award speech and the ceremony at which he read it present a triple interest for the history and sociology of sociology. They illustrate how a shaping figure in the discipline personally experienced, reflexively viewed, and practically navigated the nexus of science, authority, and power. They mark 1993 as a pivot-year in Bourdieu’s intellectual evolution, leading to a new agenda foregrounding the state as paramount symbolic power, the alchemy of group formation, and the unfinished promise of democratic politics; and they help explain why he ventured more forthrightly into civic debate in the 1990s. Bourdieu’s ambivalent acceptance of the prize also illustrates his co...
On a state model for the SO(2n) Kauffman polynomial

Francois Jaeger presented the two-variable Kauffman polynomial of an unoriented link L as a weighted sum of HOMFLY-PT polynomials of oriented links associated with L. Murakami, Ohtsuki and Yamada (MOY) used planar graphs and a recursive evaluation of these graphs to construct a state model for the sl.n/link invariant (a one-variable specialization of the HOMFLY-PT polynomial). We apply the MOY framework to Jaeger’s work, and construct a state summation model for the SO.2n/ Kauffman polynomial.
The preparation and intra- and intermolecular addition reactions of acyclic N-acylimines: application to the synthesis of (+/-)-sertraline.

Intramolecular endo-cyclization reactions of N-acyliminium ions have seen wide application for the synthesis of heterocyclic compounds. The corresponding exocyclic variant, which would provide 1-aminotetralin derivatives, for example, has little precedent. We have discovered that acyclic N-acylcarbamates can be readily reduced to the corresponding N-acylhemiaminal derivatives in high yield using DIBAL as the reducing agent. These intermediates are remarkably stable and, if desired, can be purified and stored. The acyclic N-acylhemiaminals undergo both intra- and intermolecular nucleophilic addition reactions mediated by strong Lewis acids, such as TiCl4. Diastereoselectivity, induced either by a substituent on the newly formed ring, or by utilizing a chiral ester on the carbamic acid, was disappointingly low. This methodology was successfully applied to the synthesis of the racemic form of the marketed antidepressant sertraline.
Synthesis and NMR‐spectral characterization of N,N‐dialkyl‐3‐nitroanilines, N,N‐dialkyl‐1,3‐benzenediamines and their acyl derivatives

A recently discovered method for the synthesis of N,N-dialkyl-1,3-benzenediamines with two different alkyl groups is shown to be general. This is demonstrated by the synthesis of N-butyl-N-phenethyl-1,3-benzenediamine by the condensation of 3-nitroaniline with phenyl-acetaldehyde and benzotriazole, reduction of the adduct with sodium borohydride, acylation of the resulting N-phenethyl-3-nitroaniline with butyryl chloride, catalytic reduction of the nitro group by formic acid in the presence of triethylamine and palladium and finally reduction of the butyramide carbonyl group to the butyl substituent by lithium aluminum hydride. Several other routes were less efficient or failed completely. Classical methods for the synthesis of N,N-diethyl-1,3-benzenediamine were reexamined and improved. The recommended procedure involves alkylation of 3-nitroaniline with diethyl sulfate, trapping of N-ethyl-3-nitroaniline (by-product) by benzoylation, distillation of N,N-diethyl-3-nitro-aniline under reduced pressure and reduction of the nitro group by formic acid catalyzed by palladium.
QUARK CONFINEMENT AND COLOR TRANSPARENCY IN A GAUGE-INVARIANT FORMULATION OF QCD

We examine a nonlocal interaction that results from expressing the QCD Hamiltonian entirely in terms of gauge-invariant quark and gluon fields. The interaction couples one quark color-charge density to another, much as electric charge densities are coupled to each other by the Coulomb interaction in QED. In QCD, this nonlocal interaction also couples quark color-charge densities to gluonic color. We show how the leading part of the interaction between quark color-charge densities vanishes when the participating quarks are in a color singlet configuration, and that, for singlet configurations, the residual interaction weakens as the size of a packet of quarks shrinks. Because of this effect, color-singlet packets of quarks should experience final state interactions that increase in strength as these packets expand in size. For the case of an SU(2) model of QCD based on the ansatz that the gauge-invariant gauge field is a hedgehog configuration, we show how the infinite series that represents the nonlocal interaction between quark color-charge densities can be evaluated nonperturbatively, without expanding it term-by-term. We discuss the implications of this model for QCD with SU(3) color and a gauge-invariant gauge field determined by QCD dynamics.
Neonatal hypoglycemia after beta-sympathomimetic tocolytic therapy

The effect of oral beta-sympathomimetic tocolytic therapy on neonatal serum glucose concentrations in the first several hours after delivery was examined in 12 babies. Hypoglycemia was noted in eight babies, and was sustained over at least a 30-minute period in five. The group with sustained hypoglycemia had a higher cord serum insulin concentration, a lower serum glucose nadir, and a more rapid initial rate of serum glucose disappearance than those babies with normoglycemia or transient hypoglycemia. Sustained hypoglycemia was observed in five of six babies delivered within two days of the termination of tocolytic therapy, but was not present in any of six babies delivered five or more days after the end of tocolytic therapy. Speculations as to the interaction between beta-sympathomimetic tocolytic drugs administered to the mother and fetal and neonatal glucose metabolism are made.
The response of nonlinear systems to modulated high-frequency input

We study the response of a single-degree-of-freedom system with cubic nonlinearities to an amplitude-modulated excitation whose carrier frequency is much higher than the natural frequency of the system. The only restriction on the amplitude modulation is that it contain frequencies much lower than the carrier frequency of the excitation. We apply the theory to different types of amplitude modulation and find that resonant excitation of the system may occur under some conditions.
M-Vax: an autologous, hapten-modified vaccine for human cancer

The author has devised a novel approach to the immunotherapy of cancer based on modification of autologous tumor cells with the hapten, dinitrophenyl (DNP). This technology is being developed by AVAX Technologies (MO, USA) as a treatment for melanoma under the brand name, M-VaxTM. The treatment program consists of multiple intradermal injections of DNP-modified autologous tumor cells mixed with bacille Calmette–Guerin as an immunological adjuvant. Administration of DNP vaccine to patients with metastatic melanoma induces a unique reaction – the development of inflammation in metastatic masses. Following DNP-vaccine treatment, almost all patients develop delayed-type hypersensitivity (DTH) to autologous, DNP-modified melanoma cells and about half also exhibit DTH to autologous, unmodified tumor cells. The toxicity of the vaccine is mild, consisting mainly of papules or pustules at the injection sites. Clinical trials have been conducted in two populations of melanoma patients: Stage IV with measurable meta...
Facile desilylative hydroxyalkylation and acylation of 1-trimethylsilylmethyl-2-pyridone

Abstract The title compound provides the first preparatively useful synthon for the α-carbanion of 1-methyl-2-pyridone. Desilylative hydroxyalkylation and acylation give the appropriate 1-(β-hydroxyalkyl) or 1-(β-oxoalkyl)-2-pyridones.
Electromagnetic interactions for the two-body spectator equations

This paper presents a new non-associative algebra which is used to (1) show how the spectator (or Gross) two-body equations and electromagnetic currents can be formally derived from the Bethe-Salpeter equation and currents if both are treated to all orders, (2) obtain explicit expressions for the Gross two-body electromagnetic currents valid to any order, and (3) prove that the currents so derived are exactly gauge invariant when truncated consistently to any finite order. In addition to presenting these new results, this work complements and extends previous treatments based largely on the analysis of sums of Feynman diagrams.
Diffeomorphism invariant actions for partial systems

Abstract Given a diffeomorphism invariant theory and a bounded region R of spacetime specified in a diffeomorphism invariant way, we show that the usual variational principle within R may be modified so that it becomes invariant under both diffeomorphisms that do and do not preserve the boundaries of R .
Crystal structure of the Zr3Pd4 phase

Abstract A new binary ZrPd phase with Zr3Pd4 stoichiometry was found. The structure of the phase was investigated by transmission electron microscopy and powder neutron diffraction. The structure belongs to the Pu3Pd4 structure type, which has a rhombohedral R 3 space group with 42 atoms in a hexagonal cell. Modifications of the ZrPd phase diagram which accommodate the new phase are suggested.
Chaotic flow in a 2D natural convection loop with heat flux boundaries

Abstract This computational study investigates the nonlinear dynamics of unstable convection in a 2D thermal convection loop (i.e., thermosyphon) with heat flux boundary conditions. The lower half of the thermosyphon is subjected to a positive heat flux into the system while the upper half is cooled by an equal-but-opposite heat flux out of the system. Water is employed as the working fluid with fully temperature dependent thermophysical properties and the system of governing equations is solved using a finite volume method. Numerical simulations are performed for varying levels of heat flux and varying strengths of gravity to yield Rayleigh numbers ranging from 1.5 × 10 2 to 2.8 × 10 7 . Simulation results demonstrate that multiple regimes are possible and include: (1) conduction, (2) damped, stable convection that asymptotes to steady-state, (3) unstable, Lorenz-like chaotic convection with flow reversals, and (4) high Rayleigh, aperiodic stable convection without flow reversals. Delineation of the various flow regimes, as characterized by the temporal evolution of bulk mass flow rate, is obtained in terms of heat flux, gravity, and the Rayleigh number. Temporal frequencies of the oscillatory behavior and residence time in a circulatory direction are explored and described for the various thermal and gravitational forcing (Rayleigh number) applied to the system.
Optimizing n-variate (n+k)-nomials for small k

We give a high precision polynomial-time approximation scheme for the supremum of any honest n-variate (n+2)-nomial with a constant term, allowing real exponents as well as real coefficients. Our complexity bounds count field operations and inequality checks, and are quadratic in n and the logarithm of a certain condition number. For the special case of n-variate (n+2)-nomials with integer exponents, the log of our condition number is sub-quadratic in the sparse size. The best previous complexity bounds were exponential in the sparse size, even for n fixed. Along the way, we partially extend the theory of Viro diagrams and A-discriminants to real exponents. We also show that, for any fixed ?>0, deciding whether the supremum of an n-variate (n+n?)-nomial exceeds a given number is NPR-complete.
An efficient synthesis of tertiary amines from nitriles in aprotic solvents

Abstract Tertiary amines are utilized extensively as non-nucleophilic proton scavengers for a number of organic transformations. Herein we report the efficient syntheses of tertiary alkyl amines from their corresponding alkyl nitriles in the presence of a heterogeneous palladium catalyst and a source of dihydrogen in aprotic solvents. The reaction is atom economic, the conditions are mild, and the isolated yields are virtually quantitative. The degree of amine alkylation shows some solvent dependency; in polar protic solvents such as ethanol or methanol, the reaction affords a mixture of products with the secondary alkyl amine as the major product.
Economic impact of a ban on the use of over the counter antibiotics in U.S. swine rations

Abstract The U.S. pork industry routinely adds antibiotics to rations of weaned pigs both to prevent illness before symptoms emerge and to increase growth rates. The European Union (EU) is in the process of restricting feed use of antibiotics, and the U.S. is currently reviewing the practice. The strategic issue facing U.S. pork producers is whether another food safety dispute with the EU is worthwhile. This paper evaluates the economic impact of such a ban in the U.S. The analysis uses a set of technical assumptions derived from the experience of a similar ban in Sweden and finds such a ban would increase production costs per head between $5.24 and $6.05; net profit would decline $0.79 per head. On the consumer side, the effects of a ban would raise the retail price of pork by 5 cents per pound.
Excimer Laser Assisted Deposition of GaAs, AlAs, and [Al.Ga]as from Lewis Acid-Base Adducts

Abstract : Laser-assisted deposition of GaAs, AL,As and (AL,Ga)As thin films on Ge100 substrates from trimethylgallium-trimethylarsenic and trimethylaluminum-trimethylarsenic Lewis acid-base adduct source materials is reported. A parametric study has been performed in which reactive gas pressure, substrate temperature, laser fluence, laser wavelength (248 nm or 193 nm), and orientation of the laser beam with respect to the substrate have been varied. In the case of irradiation parallel to the substrate, stoichiometric films of GaAs and (AL,Ga)As have been obtained. The data suggest that for irradiation perpendicular to the substrate a competition exists between desorption and photodeposition, which adversely affects film stoichiometry under the conditions studied.
High-speed resonant cavity enhanced Ge photodetectors on reflecting Si substrates for 1550-nm operation

We have designed and fabricated high-speed resonant cavity enhanced germanium (Ge) Schottky photodetectors on a silicon-on-insulator substrate. These back-illuminated detectors have demonstrated 3-dB bandwidths of more than 12 GHz at 3-V reverse bias and a peak quantum efficiency of 59% (R=0.73 A/W) at the resonant wavelength of /spl sim/1540 nm. Time domain measurements of our Ge photodetectors with diameters of up to 48 /spl mu/m show transit-time limited impulse responses corresponding to bandwidths of at least 6.7 GHz, making these detectors compatible with 10-Gb/s data communication systems.
SHOEBOX: a personal file handling system for textual data

The SHOEBOX system, a part of MITRE's long-term effort in the development of text-processing systems, is designed to be the electronic analog of a personal desk file drawer. A desk drawer is conveniently at hand and readily accessible. It contains documents, reports, adversaria---probably most of which, if the work of others, haven't been thoroughly read, or if one's own work, remain unfinished. This material is organized under whatever whimsical scheme suits one's fancy; and as one's fancy changes, the file contents are variously combined or further segregated. (Or at least one would like to perform that kind of reorganization, at present a formidable undertaking.) Needless to add, the texts are set down in a variety of formats, the only common factor among them all being a close adherence to the grammar rules of natural language. Such an unstructured environment is the bane of digital mechanization, but it is to this problem that we have addressed ourselves.
THE EXTENDED FAMILY IN TRANSITION: A STUDY OF THE FAMILY LIFE OF OLD PEOPLE IN THE NETHERLANDS

SUMMARY The data for this study were gathered in two Dutch townships, where a high proportion of the aged lived in extended families. Personal interviews were held with a total of 355 old persons. The attitudes and behaviour of the aged respondents toward sharing a household with children suggest that this norm does not have the salience nor is it as extensive as has been assumed. This conclusion is supported by the following pieces of evidence gleaned from the study: the deviations from the extended family norm; some indications of avoidance of joint living arrangements; an absence of common meanings and values between the aged and their children; and the high proportion of old people who express themselves negatively toward the extended family. The practice of leaving the farm to the oldest son and the limited occupational opportunities in the rural townships contribute to the decline in the prevalence of the extended family by virtue of the occupational and residential mobility of the sons. Given the above, one can predict that the emerging family structure in the eastern part of the Netherlands will be a household separate from children, a type that is characteristic of industrial society. But we can suggest on the basis of the evidence in the study that this set of events need not lead to the isolation and alienation of the aged from the adult generation.
Tensor algebras and displacement structure. IV. Invariant kernels

In this paper we investigate a class of invariant positive definite kernels on the free semigroup on N generators. We provide a combinatorial description of the positivity of the kernel in terms of Dyck paths and then we find a displacement equation that encodes the invariance property of the kernel.
Peer Effects in the Diffusion of Solar Photovoltaic Panels

Social interaction (peer) effects are recognized as a potentially important factor in the diffusion of new products. In the case of environmentally friendly goods or technologies, both marketers and policy makers are interested in the presence of causal peer effects as social spillovers can be used to expedite adoption. We provide a methodology for the simple, straightforward identification of peer effects with sufficiently rich data, avoiding the biases that occur with traditional fixed effects estimation when using the past installed base of consumers in the reference group. We study the diffusion of solar photovoltaic panels in California and find that at the average number of owner-occupied homes in a zip code, an additional installation increases the probability of an adoption in the zip code by 0.78 percentage points. Our results provide valuable guidance to marketers designing strategies to increase referrals and reduce customer acquisition costs. They also provide insights into the diffusion process of environmentally friendly technologies.
Synthesis and characterization of highly fluorinated diamines and benzoxazines derived therefrom

A novel method for the synthesis of highly fluorinated benzoxazines in a high yield derived form a α,ω-diamine-polyfluoroalkane and α,ω-dianiline-polyfluoroalkane is described. The synthetic method increases the yield by 20% and reduces the reaction time by 90% in comparison to the currently known method, allowing synthesis of large quantity of highly fluorinated diamines. The diamines are used as the precursors for benzoxazine compounds. The diamines and benzoxazines are obtained in high yield and purity. The structures are characterized by nuclear resonance spectroscopy (NMR) and Fourier transform infrared spectroscopy (FT-IR).
Choline Metabolism. I. the Occurrence and Prevention of Hemorrhagic Degeneration in Young Rats on a Low Choline Diet

1. A new effect of a deficiency of choline in young rats in deseribed. 2. The deficiency is characterized by an exterme toxic state in which there is a marked hemorrhagic enlargement and degeneration of the kidneys, a regression of the thymus, and en enlargement of the spleen. 3. The deficiency is prevented by amounts of choline too small to influence the deposition of liver fat. 4. The requirement for choline is greater in young than in older rats. 5. It is suggested that choline is essential for the maintenance of the normal structure of tissues as well as for its lipotropic action.
Highly regioselective hypervalent iodine mediated ring cleavage and ring expansion reactions of some pentacyclo[5.4.0.02,6.03,10.05,9]undecane derivatives

Abstract Iodosylbenzene-iodine mediated oxidative fragmentation of 3-hydroxy-4-oxa-5-methyl-hexacyclo[5.4.1.02,6-.03,10.0{5,9}.0{8,11}]dodecane (1) proceeds with regioselective C(3)-C(10) σ-bond cleavage to afford exo-10-iodo-4-oxa-5-methylpentacyclo[5.4.1.02,6.05.9.08.11]dodecan-3-one (4) in 94% yield. The corresponding reaction of 1-hydroxy-12-oxapentacyclo[5.4.1.02,6.0{3,10}.05,9]dodecane (6) proceeds with regioselective C(1)-C(11) σ-bond cleavage, thereby affording endo-9-(iodomethyl)-5-oxatetracyclo[6.3.0.02,6.03.10]undecan-4-one (9, 94% yield). Treatment of exo-8-(bromoethynyl)-endo-8-hydroxypentacyclo[5.4.1.02,6.03,10.05,9]undecane (12) with PhI(OH)(OTs)-12 resulted in highly regioselective ring expansion to afford 8-[(Z-)bromoiodomethylene]pentacycl[5.4.0.02,6.03,11.05,10]dodecan-9-one (13) as the exclusive reaction product (67% yield). The structures of 4, 9, exo-8-ethynyl-endo-8-hydroxypentacyclo[5.4.1.02,6.03,10.05,9]-undecane (11), and 13 were established unequivocally via single crystal X-ray structural analysis.
EFFECTS OF AMINOPHYLLINE ON THE VENTILATION AND METABOLIC RATE IN PREMATURE INFANTS WITH APNEA

Eight premature infants (mean B.W. 1080 g, Gestational age 28 weeks) with severe idiopathic apnea (> 20 sec.) were treated with Aminophylline 2 mg/kg q. 6 hrs. iv during the first week of life. Minute ventilation (VE), ventilatory response to 4% CO2, dynamic lung compliance (CL), end tidal CO2 (PACO2), oxygen consumption (VO2) and arterial blood gases were determined before and 48 hrs. after treatment was started. All measurements were done during sleep, after feedings. Lung compliance and oxygen requirements did not change significantly after treatment. Alveolar ventilation (VA) was calculated assuming an RQ of 0.8. VA increased from 88 ml/min to 149 ml/min, mainly because of a rise in tidal volume. This increase of 70% can only partially be explained by the 20% increase in metabolic rate, indicating an additional rise in respiratory center output. This rise was reflected in a significant shift of the CO2 response curve to the left without change in its slope as reported in the adult. In conclusion, Aminophylline reduces the incidence of apneic spells in prematures by increasing their central ventilatory drive. This finding is consistent with the theory that idiopathic apnea is related to a respiratory center malfunction.
THE INTRA-INDUSTRY EFFECTS OF OPEN MARKET SHARE REPURCHASES: CONTAGION OR COMPETITIVE?

We examine the extent to which announcements of open market share repurchase programs affect the valuation of competing firms in the same industry. On average, although firms announcing open market share repurchase programs experience a significantly positive stock price reaction at announcement, portfolios of rival firms in the same industry experience a significant and contemporaneous negative stock price reaction. This suggests that perceived changes in the competitive positions of the repurchasing firms occur at the expense of rival firms and dominate any signals of favorable industry conditions. Thus, the competitive intra-industry effects of open market repurchases outweigh any contagion effects. In addition, cross-sectional tests indicate that these competitive effects are more pronounced in industries characterized by a lower degree of competition and less correlation between the stock returns of the repurchasing firm and its rivals.
Simplex optimization of electroreduction of oxygen mediated by methyl viologen supported on zeolite-modified carbon paste electrode

Abstract By using the methyl viologen—oxygen system as a model, zeolites Y and A were shown to be promising as supports for electrocatalysts, and perhaps as sites for preconcentration of substrates as well. Simplex optimization was used to reach a maximum catalytic peak current for the reduction of oxygen using a modified electrode consisting of carbon paste mixed with the sodium form of zeolite Y . The electrochemistry was carried out in aqueous lithium perchlorate solution buffered at pH 7.00. There were four parameters varied to give a maximum peak current due to oxygen reduction: 1. concentration of methyl viologen in solution; 2. percentage (by mass) of Y zeolite mixed into carbon paste electrode; 3. time of exposure of zeolite-modified electrode to viologen solution prior to voltammetric experiment; 4. duration of oxygenation of solution prior to experiment. Peak current for reduction of oxygen showed a maximum with respect to parameters 1 and 2. Peak currents increased then leveled off as parameters 3 and 4 were increased. The optimal response was obtained when carbon paste electrode containing 49 wt% zeolite Y was immersed in a 32 mM solution of methyl viologen in aqueous electrolyte solution saturated with oxygen. An equilibration period of 46 min was required to achieve an optimal degree of ion exchange of methyl viologen cation radical into the zeolite prior to the electrochemical experiment. In addition to optimizing peak current, the simplex method allowed conclusions to be drawn about the interrelationships among parameters in the electrochemical system.
Collisional Plasma Models with APEC/APED: Emission-Line Diagnostics of Hydrogen-like and Helium-like Ions

New X-ray observatories (Chandra and XMM-Newton) are providing a wealth of high-resolution X-ray spectra in which hydrogen- and helium-like ions are usually strong features. We present results from a new collisional-radiative plasma code, the Astrophysical Plasma Emission Code (APEC), which uses atomic data in the companion Astrophysical Plasma Emission Database (APED) to calculate spectral models for hot plasmas. APED contains the requisite atomic data such as collisional and radiative rates, recombination cross sections, dielectronic recombination rates, and satellite line wavelengths. We compare the APEC results to other plasma codes for hydrogen- and helium-like diagnostics and test the sensitivity of our results to the number of levels included in the models. We find that dielectronic recombination with hydrogen-like ions into high (n = 6-10) principal quantum numbers affects some helium-like line ratios from low-lying (n = 2) transitions.
Stochastic modeling for magnetic resonance quantification of myocardial blood flow

Quantification of myocardial blood flow is useful for determining the functional severity of coronary artery lesions. With advances in MR imaging it has become possible to assess myocardial perfusion and blood flow in a non-invasive manner by rapid serial imaging following injection of contrast agent. To date most approaches reported in the literature relied mostly on deriving relative indices of myocardial perfusion directly from the measured signal intensity curves. The central volume principle on the other hand states that it is possible to derive absolute myocardial blood flow from the tissue impulse response. Because of the sensitivity involved in deconvolution due to noise in measured data, conventional methods are sub-optimal, hence, we propose to use stochastic time series modeling techniques like ARMA to obtain a robust impulse response estimate. It is shown that these methods when applied for the optical estimation of the transfer function give accurate estimates of myocardial blood flow. The most significant advantage of this approach, compared with compartmental tracer kinetic models, is the use of a minimum set of prior assumptions on data. The bottleneck in assessing myocardial blood flow, does not lie in the MRI acquisition, but rather in the effort or time for post processing. It is anticipated that the very limited requirements for user input and interaction will be of significant advantage for the clinical application of these methods. The proposed methods are validated by comparison with mean blood flow measurements obtained from radio-isotope labeled microspheres.© (2000) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
How quantum is the big bang

When quantum gravity is used to discuss the big bang singularity, the most important, though rarely addressed, question is what role genuine quantum degrees of freedom play. Here, complete effective equations are derived for isotropic models with an interacting scalar to all orders in the expansions involved. The resulting coupling terms show that quantum fluctuations do not affect the bounce much. Quantum correlations, however, do have an important role and could even eliminate the bounce. How quantum gravity regularizes the big bang depends crucially on properties of the quantum state.
Design of a high-impact survivable robot

This paper presents the design, construction, and testing of a two-wheeled low-cost mobile robot platform that has high survivability when subjected to large impact forces and general rough handling. The design of the drive transmission system and integrated suspension system is developed, along with general equations of motion describing their dynamics. Analyses were conducted to insure stability of the various subsystems and optimize parameters for the desired vibration characteristics. Equations of motion were also developed to describe the rocking chassis phenomenon inherent to the two-wheeled design. A flywheel compensation scheme which helps eliminate the rocking chassis problem is also outlined. An impact analysis combining theory and empirical data was used to predict the survivability threshold. Finally, three series of experiments were conducted, with the first two followed by design improvements. In contrast to currently available commercial robots, our new design employs a flexible mechanical platform capable of absorbing energy during high load impacts. This design was substantiated during the final tests when the robot survived a third story drop without any damage.
Wavelet-based multiresolution expectation maximization image reconstruction algorithm for positron emission tomography (PET)

Maximum Likelihood estimation based Expectation Maximization (EM) reconstruction algorithm has shown to provide good quality reconstruction for PET. Our previous work introduced the multigrid and multiresolution concept for PET image reconstruction using EM. This work transforms the MGEM and MREM algorithm to a Wavelet based Multiresolution EM algorithm by extending the concept of switching resolutions in both image and data spaces. The multiresolution data space is generated by performing a 2D-wavelet transform on the acquired tube data that is used to reconstruct images at different spatial resolutions. Wavelet transform is used for multiresolution reconstruction as well as adapted in the criterion for switching resolution levels. The advantage of the wavelet transform is that it provides very good frequency and spatial (time) localization and allows the use of these coarse resolution data spaces in the EM estimation process. The multiresolution algorithm recovers low frequency components of the reconstructed image at coarser resolutions in fewer iterations, reducing the number of iterations required at finer resolution to recover high frequency components. This paper also presents the design of customized biorthogonal wavelet filters using the lifting method, which are used for data decomposition and image reconstruction.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
Cosmic Filaments in Superclusters

Large-scale structure calculations show that modest overdensity filaments will connect clusters of galaxies and these filaments are reservoirs of baryons, mainly in gaseous form. To determine whether such filaments exist, we have examined the UV absorption line properties of three active galactic nuclei (AGNs) projected behind possible filaments in superclusters of galaxies; the AGNs lie within 3 Mpc of the center lines of loci connecting clusters. All three lines of sight show absorption in Lyα, Lyβ, and/or O VI at redshifts within about 1300 km s-1 of the nearby galaxy clusters that would define the closest filaments. For one AGN, the absorption-line redshifts are close to the emission-line redshift of the AGN, so we cannot rule out self-absorption for this object. These absorption-line associations with superclusters are unlikely to have occurred by chance, a result consistent with the presence of cosmic filaments within superclusters.
Stability and limit cycles of parametrically excited, axially moving strings

Tension fluctuations are the dominant source of excitation in automotive belts. In particular designs, these fluctuations may parametrically excite large amplitude transverse belt vibrations and adversely impact belt life. This paper evaluates an efficient discrete model ofa parametrically excited translating belt. The efficiency derives from the use of translating string eigenfunctions as a basis for a Galerkin discretization of the equations of transverse belt response. Accurate and low-order models lead to simple closed-form solutions for the existence and stability of limit cycles near parametric instability regions. In particular, simple expressions are found for the stability boundaries of the general nth-mode principal parametric instability regions and the first summation and difference parametric instability regions. Subsequent evaluation of the weakly nonlinear equation of motion leads to an analytical expression for the amplitudes (and stability) of nontrivial limit cycles that exist around the nth-mode principal parametric instability regions. Example results highlight important conclusions concerning the response of automotive belt drives.
Catalytic Enantioselective Addition of Thioacids to Trisubstituted Nitroalkenes.

The first example of a catalytic enantioselective addition to and nitronate protonation of trisubstituted nitroalkenes to produce highly enantioenriched products with a tetrasubstituted carbon is reported. Thioacids added in excellent yields and with high enantioselectivities to both activated and unactivated nitroalkenes. The 1,2-nitrothioacetate products can be readily converted in two steps to biomedically relevant 1,2-aminosulfonic acids without loss of enantiopurity.
Design and optimization strategies for muscle-like direct-drive linear permanent-magnet motors

We report a new approach to the design of direct-drive linear permanent-magnet motors for use in general-purpose robotic actuation, with particular attention to applications in bird-scale flapping-wing robots. We show a simple, quantitative analytical modeling framework for this class of actuators, and demonstrate inherent scaling properties that allow the production of motors with force densities and efficiencies comparable to those of biological muscles. We illustrate the effectiveness of our model with finite-element analysis and a comparison with commercially available motors, and discuss future plans for experimental validation. We show how this model leads to a set of practical design specifications for muscle-like motors, and examine the resulting trade-off between thermal management and motor fabrication complexity.
Using Hubble Space Telescope Imaging of Nuclear Dust Morphology to Rule Out Bars Fueling Seyfert Nuclei

If active galactic nuclei (AGN) are powered by the accretion of matter onto massive black holes, how does the gas in the host galaxy lose the required angular momentum to approach the black hole? Gas easily transfers angular momentum to stars in strong bars, making them likely candidates. Although ground-based searches for bars in active galaxies using both optical and near-infrared surface brightness have not found any excess of bars relative to quiescent galaxies, the searches have not been able to rule out small-scale nuclear bars. To look for these nuclear bars we use Hubble Space Telescope Wide Field and Planetary Camera 2 and Near Infrared Camera and Multi-Object Spectrometer color maps to search for the straight dust lane signature of strong bars. Of the twelve Seyfert galaxies in our sample, only three have dust lanes consistent with a strong nuclear bar. Therefore, strong nuclear bars cannot be the primary fueling mechanism for Seyfert nuclei. We do find that a majority of the galaxies show an spiral morphology in their dust lanes. These spiral arms may be a possible fueling mechanism.
Characterization of silicon on insulator substrates using reflection mode double-crystal X-ray topography

Abstract The strain distributions of various silicon-on-insulator (SOI) wafers were studied using Bragg reflection mode double-crystal topography analysis. These SOI samples included the separation by implanted oxygen (SIMOX), the zone melt recrystallization (ZMR), and the bond and etch-back silicon-on-insulator (BESOI). The inherent warpage of each SOI sample was revealed by X-ray double-crystal topography (DCT). Dislocation loops and surface-terminating defects were also observed on the ZMR sample. The defect density was evaluated by double-crystal rocking curve (DCRC) analysis using a symmetric (004) set-up. The relative peak intensities and full width at half maxima (FWHM) were measured. The quality of superficial silicon layers of most SOI wafers was similar to the quality of a single-crystal silicon, except the ZMR sample. According to these analyses, SIMOX wafers provide the best single-crystal quality and consistent lattice characteristics under various fabrication processes.
The Intentions and Heritage of Descartes and Locke: Toward a Recognition of the Moral Basis of Modern Psychology

Summary Given the recent discussions about the proper stance of the American Psychological Association vis-a-vis a wide range of moral issues, it might be useful to reflect upon the historical foundations of contemporary psychology. This article reviews this history from the seventeenth century to the present, placing special emphasis upon the role that moral concerns played in the development of all the modern sciences of man, including psychology. It presents evidence in support of the thesis that the intentions or concerns of Descartes and Locke were largely moral and that similar intentions underlay the work of virtually all of the subsequent proponents of “the science of Man” up to the turn of the twentieth century. It then discusses the twentieth-century conflict between this heritage of moral concern and the ideal of a “value-free,” logically “justified,” and “pure” science of psychology. While acknowledging the lively debate surrounding this conflict, it argues that the conflict itself is more app...
Experimental Study of Heat Conduction in Aqueous Suspensions of Aluminum Oxide Nanoparticles

We report measurements of the thermal conductivity of aqueous suspensions of aluminum oxide nanoparticles with nominal diameters of 20 nm, 30 nm, and 45 nm and at volume concentrations up to 10%. Potential complications in the pulsed transient hot-wire technique for characterizing nanofluids are examined, which motivate the development of a microhot strip setup with a small thermal time constant. The average particle size is monitored for samples subjected to different durations of sonication and the thermal conductivity is determined at two different temperatures for each of the samples. The present data do not reveal any anomalous enhancement in the thermal conductivity previously reported for comparable nanofluids. The concentration dependence of the thermal conductivity can be explained using the conventional effective medium model with a physically reasonable set of parameters.
Data handling by control word techniques

Early computing machines executed programs which could be specified by pluggable wiring, paper tape, or cards. These programs remained unchanged during their execution. The invention of the stored program made it possible to treat a program as data. This invention was a basic step forward in the development of computing machines. It then was possible for any instruction of a program to be modified by the program itself. In practice this general facility was used mainly for the modification of addresses. Subsequently, it became apparent that programmed address computation, though sufficient in theory, was cumbersome in practice. Too much computing time and program space were required to perform these auxiliary operations. As a remedy, an address register, also called index register or B-line, was provided, whose contents could be added to the operand address. In recent machines, several index registers, up to one hundred, have been made available.
On the output of acoustical sources

Contents: (1) a theoretical basis for local power calculation; (2) source radiation in the presence of a half-plane; (3) radiation from a line source near an edge at which a Kutta condition holds; (4) radiation by a point source above a plane independence boundary; and (5) power output of a point source in a uniform flow.
ARCH and GARCH models vs. martingale volatility of finance market returns

Abstract ARCH and GARCH models assume either i.i.d. or ‘white noise’ as is usual in regression analysis, while also assuming memory in a conditional mean square fluctuation with stationary increments. We will show that ARCH/GARCH is inconsistent with uncorrelated increments, violating the i.i.d. and ‘white’ assumptions, and violating finance data and the efficient market hypothesis as well.
X-Ray Synchrotron Emission From 10-100 TeV Cosmic-Ray Electrons In The Supernova Remnant SN 1006

We present the results of a joint spectral analysis of RXTE PCA, ASCA SIS, and ROSAT PSPC data of the supernova remnant SN 1006. This work represents the first attempt to model both the thermal and nonthermal X-ray emission over the entire X-ray energy band from 0.12 to 17 key. The thermal flux is described by a nonequilibrium ionization model with an electron temperature kTe = 0.6 key, an ionization timescale n(sub 0)t = 9 x 10(exp 9)/cc s, and a relative elemental abundance of silicon that is 10 - 18 times larger than the solar abundance. The nonthermal X-ray spectrum is described by a broken power law model with low- and high-energy photon indices Gamma(sub 1) = 2.1 and Gamma(sub 2) = 3.0, respectively. Since the nonthermal X-ray spectrum steepens with increasing energy, the results of the present analysis corroborate previous claims that the nonthermal X-ray emission is produced by synchrotron radiation. We argue that the magnetic field strength is significantly larger than previous estimates of about 10 micro G and arbitrarily use a value of 40 micro G to estimate the parameters of the cosmic-ray electron, proton, and helium spectra of the remnant. The results for the ratio of the number densities of protons and electrons (R = 160 at 1 GeV), the total energy in cosmic rays (E(sub cr) = 1 x 10(exp 50) ergs), and the spectral index of the electrons at 1 GeV (Gamma(sub e) = 2.14 +/- 0.12) are consistent with the hypothesis that Galactic cosmic rays are accelerated predominantly in the shocks of supernova remnants. Yet, the remnant may or may not accelerate nuclei to energies as high as the energy of the "knee," depending on the reason why the maximum energy of the electrons is only 10 TeV.
Organizational Design and Environmental Volatility

I investigate the link between the volatility of a …rm’s operating environment and its preferred organizational structure, as determined by the allocation of decision rights, the compensation structure of the managers and the degree of operational integration. The results are broadly consistent with the common wisdom regarding the …t between organizational design and the environment. Volatile environments are populated by organizations that have loosely coupled operations to maintain local responsiveness, together with decentralized decision-making and pay that is tied primarily to divisional performance. Stable environments, on the other hand, are populated by organizations that have tightly integrated operations to realize cost savings, together with (typically) centralized decision-making and pay that is closely tied to …rm-level performance. The results also re…ne these relationships. For example, while decentralization and volatility are positively associated in equilibrium, volatility is not directly causing decentralization. Instead, decentralization arises only as a part of the overall adjustment in organizational design and simply decentralizing decision-making as a response to an increase in volatility would actually worsen organizational performance.
Novel asymmetric synthesis of a bicyclo[3.1.0]hexane derivative by an efficient retro-diels-alder strategy

Abstract The first preparation of enantiomerically pure bicyclo[3.1.0]hexane-2-one-6-carboxylic acid ethyl ester (1), a valuable synthetic intermediate, is described. The synthesis features a retro-Diels-Alder reaction as a key step. Conditions which allow for a high yielding thermal conversion of 3 to 4 are described.