cssi/SciSciGPT-SciSciNet huggingface dataset:
MathPaper: Mathematical Sketching with Fluid Support for Interactive Computation

We present MathPaper, a system for fluid pen-based entry and editing of mathematics with support for interactive computation. MathPaper provides a paper-like environment in which multiple mathematical expressions and even algorithms can be entered anywhere on the page. Mathematical expressions can also be modified using simple deletion and dragging gestures with real-time recognition and computation feedback. In addition, we support extended notations and gestures for controlling computational assistance, simplifying input, and entering algorithms, making MathPaper a user-friendly system for mathematical sketching and computation.
Performance and error analysis of KNILL'S postselection scheme in a two-dimensional architecture

Knill demonstrated a fault-tolerant quantum computation scheme based on concatenated error-detecting codes and postselection with a simulated error threshold of 3% over the depolarizing channel. We show how to use Knill's postselection scheme in a practical two-dimensional quantum architecture that we designed with the goal to optimize the error correction properties, while satisfying important architectural constraints. In our 2D architecture, one logical qubit is embedded in a tile consisting of 5×5 physical qubits. The movement of these qubits is modeled as noisy SWAP gates and the only physical operations that are allowed are local one- and two-qubit gates. We evaluate the practical properties of our design, such as its error threshold, and compare it to the concatenated Bacon-Shor code and the concatenated Steane code. Assuming that all gates have the same error rates, we obtain a threshold of 3:06 × 10-4 in a local adversarial stochastic noise model, which is the highest known error threshold for concatenated codes in 2D. We also present a Monte Carlo simulation of the 2D architecture with depolarizing noise and we calculate a pseudo-threshold of about 0:1%. With memory error rates one-tenth of the worst gate error rates, the threshold for the adversarial noise model, and the pseudo-threshold over depolarizing noise, are 4:06 × 10-4 and 0.2%, respectively. In a hypothetical technology where memory error rates are negligible, these thresholds can be further increased by shrinking the tiles into a 4 × 4 layout.
THE COMMON EXTERNAL TARIFF IN A CUSTOMS UNION: VOTING, LOGROLLING, AND NATIONAL GOVERNMENT INTERESTS

Missing from the analysis of customs unions has been a consideration of collective decision-making by countries regarding the union's common trade policy. In the case of the common European external tariff, how governments voted was not public information. This paper uses a unique dataset to derive member states' tariff preferences, which are then used to establish the decision rule before 1987, when individual governments had veto power. Results indicate a principle of unanimity, as well as the presence of logrolling. The political equilibrium for the common external tariff is also illustrated to have shifted as a result of union enlargements.
Overconstrained linear estimation of radial distortion and multi-view geometry

This paper introduces a new method for simultaneous estimation of lens distortion and multi-view geometry using only point correspondences. The new technique has significant advantages over the current state-of-the art in that it makes more effective use of correspondences arising from any number of views. Multi-view geometry in the presence of lens distortion can be expressed as a set of point correspondence constraints that are quadratic in the unknown distortion parameter. Previous work has demonstrated how the system can be solved efficiently as a quadratic eigenvalue problem by operating on the normal equations of the system. Although this approach is appropriate for situations in which only a minimal set of matchpoints are available, it does not take full advantage of extra correspondences in overconstrained situations, resulting in significant bias and many potential solutions. The new technique directly operates on the initial constraint equations and solves the quadratic eigenvalue problem in the case of rectangular matrices. The method is shown to contain significantly less bias on both controlled and real-world data and, in the case of a moving camera where additional views serve to constrain the number of solutions, an accurate estimate of both geometry and distortion is achieved.
On the possible onset of the Pioneer anomaly

We explore the possibility that the observed onset of the Pioneer anomaly after Saturn encounter by Pioneer 11 is not necessarily due to mismodeling of solar radiation pressure but instead reflects a physically relevant characteristic of the anomaly itself. We employ the principles of a recently proposed cosmological model termed "the theory of inertial centers" along with an understanding of the fundamental assumptions taken by the Deep Space Network (DSN) to attempt to model this sudden onset. Due to an ambiguity that arises from the difference in the DSN definition of expected light-time with light-time according to the theory of inertial centers, we are forced to adopt a seemingly arbitrary convention to relate DSN-assumed clock-rates to physical clock-rates for this model. We offer a possible reason for adopting the convention employed in our analysis; however, we remain skeptical. Nevertheless, with this convention, one finds that this theory is able to replicate the previously reported Hubble-like behavior of the "clock acceleration" for the Pioneer anomaly as well as the sudden onset of the anomalous acceleration after Pioneer 11 Saturn encounter. While oscillatory behavior with a yearly period is also predicted for the anomalous clock accelerations of both Pioneer 10 and Pioneer 11, the predicted amplitude is an order of magnitude too small when compared with that reported for Pioneer 10.
Faint AGN in z ≳ 6 Lyman-break galaxies powered by cold accretion and rapid angular momentum transport

We develop a radiation pressure-balanced model for the interstellar medium of high-redshift galaxies that describes many facets of galaxy formation at z ≳ 6, including star formation rates and distributions and gas accretion on to central black holes. We first show that the vertical gravitational force in the disc of such a model is dominated by the disc self-gravity supported by the radiation pressure of ionizing starlight on gas. Constraining our model to reproduce the UV luminosity function of Lyman-break galaxies (LBGs), we limit the available parameter space to wind mass-loading factors one to four times the canonical value for momentum-driven winds. We then focus our study by exploring the effects of different angular momentum transport mechanisms in the galactic disc and find that accretion driven by gravitational torques, such as from linear spiral waves or non-linear orbit crossings, can build up black hole masses by z = 6 consistent with the canonical M–σ relation with a duty cycle of unity, while accretion mediated by a local viscosity such as in an α-disc results in negligible black hole (BH) accretion. Both gravitational torque models produce X-ray emission from active galactic nuclei (AGN) in high-redshift LBGs in excess of the estimated contribution from high-mass X-ray binaries. Using a recent analysis of deep Chandra observations by Cowie et al., we can already begin to rule out the most extreme regions of our parameter space: the inflow velocity of gas through the disc must either be less than one per cent of the disc circular velocity or the X-ray luminosity of the AGN must be substantially obscured. Moderately deeper future observations or larger sample sizes will be able to probe the more reasonable range of angular momentum transport models and obscuring geometries.
Atom Interference Using Microfabricated Structures

Publisher Summary This chapter discusses the atom interference using microfabricated structures. It considers Talbot effect and other interference phenomena as a consequence of the recoil effect. Microfabricated structures provide 100% modulation of the incident atomic beam. They offer the additional advantage that their period and duty cycle (ratio of slit opening to period) can be chosen arbitrarily within the limits of current lithographic technology. The chapter discusses conditions necessary for the observation of matter–wave interference in different regimes. It provides rigorous proof of the equivalence of theories based on Fresnel–Kirchhoff integrals and on the recoil effect. The chapter also discusses a theory of the Talbot-Lau effect. It considers the Talbot and Talbot-Lau effect for a thermal beam in the limit where the characteristic length scale in the problem is larger than the Talbot length.
Vulnerability and Resilience: Two Dimensions of Rurality

The idea of resilience seems to be replacing sustainability as a defining concept for rural development. And, like sustainability, resilience is a vague concept that has many definitions and implications. It captures the idea that rural regions are exposed to shocks that require a mix of efforts both to mitigate their impact and incidence, and to adapt to a new environment after a shock event. In this respect resilience has much in common with the concept of risk management, which is pervasive in economics. In the article concepts from risk management are linked to four categories of risk to demonstrate that the type of risk can suggest specific ways to think about resilience strategies. Because rural regions are inherently exposed to high levels of risk, and have significant constraints on their ability to mitigate it, developing a way to achieve greater resilience is both crucial and difficult. This suggests that many rural regions may remain vulnerable, despite efforts to mitigate risk and buffer its impacts.
Greybody factors for a black hole in massive gravity

An exact solution was recently found in the massive gravity theory having the form of Schwarzschild-de Sitter (dS) black holes with some additional background fields. Hawking radiation will occur at the event and cosmological horizons having the blackbody spectrum, which will be modified by the geometry outside the black hole. In this paper, we study the greybody factors of a test scalar, considering its minimal coupling with the background geometry. The case of small black holes with a horizon radius much smaller than the cosmological dS radius is studied numerically. The case of near-extremal black holes with the horizon radius comparable to the cosmological dS radius is studied analytically. In addition, we considered the coupling of the test field with the background St\"uckelberg fields, which in turn leads to reductions in particle emission and some nontrivial features (resonances) in the greybody factors.
POLARIS: Agent-based modeling framework development and implementation for integrated travel demand and network and operations simulations

This paper discusses the development of an agent-based modeling software development kit, and the implementation and validation of a model using it that integrates dynamic simulation of travel demand, network supply and network operations. A description is given of the core utilities in the kit: a parallel discrete event engine, interprocess exchange engine, and memory allocator, as well as a number of ancillary utilities: visualization library, database IO library, and scenario manager. The overall framework emphasizes the design goals of: generality, code agility, and high performance. This framework allows the modeling of several aspects of transportation system that are typically done with separate stand-alone software applications, in a high-performance and extensible manner. The issue of integrating such models as dynamic traffic assignment and disaggregate demand models has been a long standing issue for transportation modelers. The integrated approach shows a possible way to resolve this difficulty. The simulation model built from the POLARIS framework is a single, shared-memory process for handling all aspects of the integrated urban simulation. The resulting gains in computational efficiency and performance allow planning models to be extended to include previously separate aspects of the urban system, enhancing the utility of such models from the planning perspective. Initial tests with case studies involving traffic management center impacts on various network events such as accidents show the potential of the system.
El ataque de Estados Unidos sobre Afganistán

La tesis general de este articulo es que el ataque de Estados Unidos sobre Afganistan es un esfuerzo para revertir el deterioro relativo del imperio estadounidense y restablecer su dominio en regiones conflictivas. La guerra de Afganistan es solo parte de una contraofensiva imperial general que tiene varios componentes: 1) restablecer la subordinacion de Europa a Washington; 2) reafirmar su control total en el Medio Oriente y en la region del Golfo Persico; 3) profundizar y extender la penetracion militar en Latinoamerica y Asia; 4) incrementar la guerra militar en Colombia y ejercer poder en el resto del continente; 5) restringir y reprimir las protestas y oposicion contra las corporaciones multinacionales (CMN) y las instituciones financieras internacionales (IFI), como el Banco Mundial (BM), el Fondo Monetario Internacional (FMI) y la Organizacion Mundial de Comercio (OMC), al sustituir los derechos democraticos por poderes dictatoriales; 6) destinar el gasto de gobierno a armas y subsidios para las CMN que estan al borde de la quiebra (lineas aereas, companias de seguros, agencias de turismo) y emplear reducciones regresivas de impuestos para frenar una recesion que se esta profundizando, la cual socavaria el apoyo publico al proyecto de construccion del imperio.
The Adhesion, Friction, and Wear of Binary Alloys in Contact With Single-Crystal Silicon Carbide

Sliding friction experiments, conducted with various iron base alloys (alloying elements are Ti, Cr, Mn, Ni, Rh and W) in contact with a single crystal silicon carbide /0001/ surface in vacuum are discussed. Results indicate atomic size misfit and concentration of alloying elements play a dominant role in controlling adhesion, friction, and wear properties of iron-base binary alloys. The controlling mechanism of the alloy properties is as an intrinsic effect involving the resistance to shear fracture of cohesive bonding in the alloy. The coefficient of friction generally increases with an increase in solute concentration. The coefficient of friction increases as the solute-to-iron atomic radius ratio increases or decreases from unity. Alloys having higher solute concentration produce more transfer to silicon carbide than do alloys having low solute concentrations. The chemical activity of the alloying element is also an important parameter in controlling adhesion and friction of alloys.
Categorical Mirror Symmetry: The Elliptic Curve

We describe an isomorphism of categories conjectured by Kontsevich. If M and f M are mirror pairs then the conjectural equivalence is between the derived category of coherent sheaves on M and a suitable version of Fukaya’s category of Lagrangian submanifolds on f M. We prove this equivalence when M is an elliptic curve and f M is its dual curve, exhibiting the dictionary in detail.
Epithelial-Mesenchymal Plasticity: A Central Regulator of Cancer Progression.

The epithelial–mesenchymal transition (EMT) program has emerged as a central driver of tumor malignancy. Moreover, the recently uncovered link between passage through an EMT and acquisition of stem-like properties indicates that activation of the EMT programs serves as a major mechanism for generating cancer stem cells (CSCs); that is, a subpopulation of cancer cells that are responsible for initiating and propagating the disease. In this review, we summarize the evidence supporting the widespread involvement of the EMT program in tumor pathogenesis and attempt to rationalize the connection between the EMT program and acquisition of stem cell traits. We propose that epithelial–mesenchymal plasticity is likely controlled by multiple varients of the core EMT program, and foresee the need to resolve the various programs and the molecular mechanisms that underlie them.
The spin‐resolved atomic velocity distribution and 21‐cm line profile of dark‐age gas

T The 21-cm hyper-fine line of atomic hydrogen (H I) is a promising probe of the cosmic dark ages. In past treatments of 21 -cm radiation it was assumed the hyperfine level populations on H I could be characterized by a velocity-independent 'spin temperature' T s determined by a competition between 21-cm radiative transitions, spin-changing collisions, and (at lower redshifts) Lyα scattering. However we show here that, if the collisional time is comparable to the radiative time, the spin temperature will depend on atomic velocity, T s = T s (υ), and one must replace the usual hyperfine level rate equations with a Boltzmann equation describing the spin and velocity dependence of the H I distribution function. We construct here the Boltzmann equation relevant to the cosmic dark ages and solve it using a basis-function method. Accounting for the actual spin-resolved atomic velocity distribution results in up to a ∼2 per cent suppression of the 21-cm emissivity, and a redshift and angular-projection-dependent suppression or enhancement of the linear power spectrum of 21-cm fluctuations of up to ∼5 per cent. The effect on the 21-cm line profile is more dramatic - its full width at half-maximum can be enhanced by up to ∼60 per cent relative to the velocity-independent calculation. We discuss the implications for 21-cm tomography of the dark ages.
Law of Large Numbers: The Theory, Applications and Technology-Based Education

Modern approaches for technology-based blended education utilize a variety of recently developed novel pedagogical, computational and network resources. Such attempts employ technology to deliver integrated, dynamically-linked, interactive-content and heterogeneous learning environments, which may improve student comprehension and information retention. In this paper, we describe one such innovative effort of using technological tools to expose students in probability and statistics courses to the theory, practice and usability of the Law of Large Numbers (LLN). We base our approach on integrating pedagogical instruments with the computational libraries developed by the Statistics Online Computational Resource (www.SOCR.ucla.edu). To achieve this merger we designed a new interactive Java applet and a corresponding demonstration activity that illustrate the concept and the applications of the LLN. The LLN applet and activity have common goals – to provide graphical representation of the LLN principle, build lasting student intuition and present the common misconceptions about the law of large numbers. Both the SOCR LLN applet and activity are freely available online to the community to test, validate and extend (Applet: http://socr.ucla.edu/htmls/exp/Coin_Toss_LLN_Experiment.html, and Activity: http://wiki.stat.ucla.edu/socr/index.php/SOCR_EduMaterials_Activities_LLN).
Endocrine effects of naloxone-induced opiate receptor blockade

To test the effect of opiate receptor blockade on hormone release in man, we administered 10 mg naloxone iv to eight normal subjects and compared the results with those found after saline infusion. Naloxone produced a rise in serum cortisol (P < 0.01), LH (P < 0.01), FSH (P < 0.05), and insulin (P < 0.05) levels but did not alter serum GH, PRL, TSH, arginine vasopressin, glucagon, T3, or T4. Naloxon e had no effect on GH levels in two subjects with active acromegaly or on TSH levels i n six subjects with primary hypothyroidism. In dynamic pituitary function testing, naloxone diminished the GH response to arginine (P < 0.05) without altering the PRL response; naloxone augmented the PRL response to TRH (P < 0.025) without affecting the TSH response. Naloxone did not significantly alter GH or PRL response to L-dopa. Naloxone enhanced the increment in serum cortisol induced by the stress of gastroscopy without changing the GH or PRL response. Naloxone increased glucose response areas (P < 0.05) after an iv gl...
The built environment and the incidence of pedestrian and cyclist crashes

This study applied negative binomial regressions to understand how the characteristics of the built environment may affect the incidence of crashes involving pedestrians and cyclists. Arterial thoroughfares, big box stores and strip commercial uses were all associated with increased risk for pedestrians and cyclists alike. Unlike earlier studies on pedestrian and cyclist crash risk, however, this study hypothesized that it was the configuration of commercial and retail uses that mattered, rather than the uses themselves. To test this, this study included a variable indicating the number of pedestrian-scaled retail uses in a community in the models. Indeed, while strip commercial uses and big box stores were a safety problem, this variable had a negative, though statistically insignificant, effect on crash incidence, suggesting that road users were modifying their behavior in these environments in a manner that prevented these crashes from occurring. Further, although earlier studies have asserted that population density was a risk factor for pedestrians and cyclists, this study found it to have a positive but weak effect on total pedestrian crashes, and no statistically meaningful effect on pedestrian killed or severely injured (KSI) crashes, nor on total or KSI crashes involving cyclists. Finally, this study found that whereas four-leg intersections were associated with increased numbers of pedestrian and cyclist crashes, three-leg intersections had no effect, or even a negative effect on crash incidence involving pedestrians and cyclists. This finding suggests that three-leg intersections may be a desirable means for increasing local street connectivity for pedestrians and cyclists without simultaneously increasing their exposure to traffic related crashes, injuries or deaths.
The Spatial Mismatch Hypothesis and Black Youth Joblessness: Evidence from the San Francisco Bay Area*

Abstract This paper presents an employment-based measure of intra-metropolitan accessibility to employment opportunities that provides strong evidence supporting the spatial mismatch hypothesis. The measure is based on intra-metropolitan variation in net employment growth rather than on spatial variation in employment levels. The principal spatial disadvantage suffered by black male youths is their residence in areas of weak or negative employment growth. In pooled employment regressions, differential accessibility explains 30 to 50% of the neighborhood employment rate differential between white and black male Bay-Area youths. In separate employment regressions by race, approximately one-fifth of the differential is attributable to differential access.
Non-Contact Determination of Free Carrier Concentration in n-GaInAsSb

GaSb-based semiconductors are of interest for mid-infrared optoelectronic and high-speed electronic devices. Accurate determination of electrical properties is essential for optimizing the performance of these devices. However, electrical characterization of these semiconductors is not straightforward since semi-insulating (SI) GaSb substrates for Hall measurements are not available. In this work, the capability of Raman spectroscopy for determination of the majority carrier concentration in n-GaInAsSb epilayers was investigated. Raman spectroscopy offers the advantage of being non-contact and spatially resolved. Furthermore, the type of substrate used for the epilayer does not affect the measurement. However, for antimonide-based materials, traditionally employed Raman laser sources and detectors are not optimized for the analysis wavelength range dictated by the narrow band gap of these materials. Therefore, a near-infrared Raman spectroscopic system, optimized for antimonide-based materials, was developed. Ga{sub 0.85}In{sub 0.15}As{sub 0.13}Sb{sub 0.87} epilayers were grown by organometallic vapor phase epitaxy with doping levels in the range 2 to 80 x 10{sup 17} cm{sup -3}, as measured by secondary ion mass spectrometry. For a particular nominal doping level, epilayers were grown both lattice matched to n-GaSb substrates and lattice-mismatched to SI GaAs substrates under nominally identical conditions. Single magnetic field Hall measurements were performed on the epilayersmore » grown on SI GaAs substrates, while Raman spectroscopy was used to measure the carrier concentration of epilayers grown on GaSb and the corresponding SI GaAs substrates. Compared to Hall measurements, Raman spectra indicated that the GaInAs/Sb epilayers grown on GaSb substrates have higher free carrier concentrations than the corresponding epilayers grown on SI GaAs substrates under nominally identical conditions. This is contrary to the assumption that for nominally identical growth conditions, the resulting carrier concentration is independent of substrate, and possible mechanisms will be discussed.« less
Analysis of a tunable single mode optical fiber coupler

We report the operation and the theoretical modeling of an efficient, tunable, and low-loss single mode fiber coupler. The coupler design follows a scheme previously reported, in which two optical fibers mounted in curved grooves in separate quartz substrates are polished until sufficient cladding material has been removed to permit optical coupling between the mated polished faces of the fibers. The results of a computer analysis of the distributed coupling taking place between the fibers are discussed, emphasizing the intuitive dependences of the coupling coefficient and effective interaction length of the device on its geometrical parameters. A detailed experimental analysis of fiber couplers follows in which we characterize two types of couplers made with different brands of single-mode fibers. Operation up to 100 percent coupling ratio and 50 dB extinction ratio between coupled and direct branch as well as operation in overcoupling regimes are demonstrated, both at visible and infrared signal wavelengths. Tuning curves are shown that emphasize the excellent tunability properties of such couplers in which the coupling ratio can be smoothly and continuously tuned between 0 and 100 percent. Experimental evidence of the relatively low loss level and very low polarization dependence of the fiber couplers are also presented. All experimental results, including an analysis of the influence of the refractive index of the intermediate layer of index-matching liquid between the polished faces of the fibers, are found to be very well predicted by our theoretical model.
Why library cards offer more privacy rights than proof of citizenship: Librarian ethics and Freedom of Information Act requestor policies

Abstract This paper demonstrates the divergent requestor privacy policies of professional librarians and the administration of the Freedom of Information Act (FOIA), and urges the federal government to adhere to librarian ethics in order to protect FOIA requestors. Section 1 of the paper provides information about the origins and purpose of the FOIA. Section 2 offers an overview of the philosophical and historical origins of library patron privacy ethics, discussing both the ethical basis for patron privacy and actual instances where library records have been sought for government surveillance of private citizens. Section 3 describes the state library laws that protect library requestors, as well as federal laws that protect non-FOIA requestor privacy rights, including the Video Privacy Protection Act (VPPA), which protects video rental records. Section 4 of the paper warns that, in the digital era, it is more important than ever to safeguard personal information like that contained in FOIA requests to prevent the stifling of information seeking activities in the United States. By modifying laws tomeet the needs of the “information age,” the United States government can embrace and utilize the ethical standards that are at the foundation of librarianship, and protect the principle that information should be free and available to the American populace.
The reaction of benzotrihalides and benzal halides with magnesium. Synthetic and mechanistic studies

Abstract The benzotrihalides (PhCX 3 ) where X = Cl, Br, and F were allowed to react with magnesium in THF at room temperature. When the halide was chloride or bromide, the trihalide gave diphenylacetylene in high yield in addition to several minor products which were identified. No reaction was observed when the halide was fluoride. When the corresponding dichloride was allowed to react with magnesium in THF, stilbene was formed as the major product. The possible mechanisms for these reactions are discussed.
Photovoltaic effect in poly‐N‐vinylcarbazole–iodine charge transfer complex

Poly-N-vinyl carbazole-iodine charge transfer photovoltaic effect spectral and intensity dependence, noting possible radiation detection and energy conversion applications
Variability of the immunologic and clinical response in dystonic patients immunoresistant to botulinum toxin injections

Immunoresistance (Ab+) to botulinum toxin type A (BTX-A) has been a serous concern since the introduction of BTX-A in the treatment of dystonia and other disorders associated with abnormal muscle contractions. We studied seven patients who developed Ab+ and later reverted to antibodynegative (Ab-) status. These seven patients, six women (mean age, 56 years; range, 41–80 years), with an average duration of dystonia for all patients of 197 months (range, 84–360 months), received a total mean cumulative dose of 1659 units (U) (range,810-1975 U), with an average dose of 207 U per visit. All of these patients became unresponsive to BTX-A treatment and became Ab+ as determined by mouse bioassay. Their response to BTX-A after they revertedd to Ab- was analyzed. The average latency between the initial BTX-A treatment and development of Ab+ was 27 months (range, 15–43 months). The average duration between the detection of Ab+ status and subsequent reversal to Ab- status was 30 months (range, 10–78 months). Six of these Ab- patients were reinjected with BTX-A, and all six benefited from repeat injections comparable with their earlier response. Three patients lost their clinical response to subsequent injections and were found to be again Ab+. Two of the five patients who became immunoresistant to BTX-A received botulinum toxin type F (BTX-F) injections and one patient received a single session of BTX-B with improvement in their symptoms. In conclusion, this unique group of patients who were Ab+ and became Ab- responded favorably to repeat BTX-A injections, but some lost the benefit with subsequent injections. These observations suggest that the anamnestic immunologic response to BTX-A can wane, but can be reactivated by repeat BTX-A treatments. The presence of antibodies did not interfere with the response to BTX-F or BTX-B injections, thus confirming the antigenic specificity of various BTX serotypes.
Recurrent nightmares? Measurement theory in de Sitter space

The idea that asymptotic de Sitter space can be described by a finite Hilbert Space implies that any quantum measurement has an irreducible innacuracy. We argue that this prevents any measurement from verifying the existence of the Poincare recurrences that occur in the mathematical formulation of quantum de Sitter (dS) space. It also implies that the mathematical quantum theory of dS space is not unique. There will be many different hamiltonians, which give the same results, within the uncertainty in all possible measurements.
An improved technique for ultrasound guided percutaneous renal biopsy

Percutaneous renal biopsy has become one of the fundamental diagnostic techniques in nephrology since its introduction in 1951 [1]. Biopsy device and guidance methods have been refined progressively during the past two decades [2] with the use of surface anatomic landmarks for guidance superseded by radiographic, computed tomographic, or ultrasonic imaging methods [3—8]. We report the application of an orthogonal ultrasonic guidance technique for renal biopsy in which the needle is visualized continuously throughout its placement. This method was initially developed for intrauterine fetal transfusion [9], and its use has been reported for transuterine fetal procedures [10, 11] and amniocentesis [12]. Methods. The patient is placed in a prone position (with the optional interposition of a bolster). Both kidneys are surveyed ultrasonically from the back and sides with a sector scanning device during varying inspiratory efforts. Unless clinical conditions specifically dictate selection of one of the kidneys, we choose that kidney for which (1) the lower pole descends below the last rib, and, (2) the lower pole is visualized satisfactorily with the ultrasonic probe positioned laterally along posterior or mid-axillary line. The probe is returned to the back and centered over the lower pole, then rotated from sagittal to transverse viewing planes and repositioned as needed, until the central ray of the image passes through the proposed biopsy site. This is usually a location lateral to the collecting system below the last or between the two lower most pyramids (Fig. 1). The operator attempts to select a path which is aligned perpendicular to the floor when kidney descent is adequate. The location of the center of the probe surface is marked on the skin with a 2-mm weal made with a ballpoint pen, tip retracted. The skin surface is prepared, draped, and locally anesthetized. A small incision is made through the weal to facilitate passage of the biopsy needle, (Tru-Cut, disposable biopsy needle, 15.2-cm cannula, 20-mm specimen notch, Travenol Laboratories, Deerfield, Illinois, USA). The needle is aligned visually along the path selected during the viewing phase. Needle passage is monitored by continuous ultrasound imaging from the lateral viewing portal with the scan plane aligned
pH-Dependent metal-based redox couples as models for proton-coupled electron transfer reactions

Abstract An overview of proton-coupled electron transfer in transition metal–ligand systems known to exhibit pH-dependent metal-based redox potentials is presented. The systems of interest can be thought of as MLH m complexes, where M is a redox-active metal and LH m is a ligand in the inner-coordination sphere containing at least one ionizable hydrogen. The use of pH-dependent redox potentials to determine proton-coupled electron transfer reactions is described, along with some important factors for designing and studying complexes that exhibit this behavior. This chemistry is illustrated by a survey of the common transition metal–ligand systems known to give pH-dependent redox potentials indicative of proton-coupled electron transfer.
An Algorithm for Using a Slide-Screw Tuner as a Computer-Controlled Impedance

In the testing of active microwave components, a common test procedure is to evaluate a device's performance when subjected to an all-phase, constant-standing-wave-ratio (APCS) load pull. Such a test specification is useful in verifying a device's stability and mismatch performance. Typically, APCS pulls are tediously performed by hand, with manually operated tuners. However, with the advent of mechanical, computer-controlled tuners, it is now possible to automate this procedure.
Incretin therapies: effects beyond glycemic control.

Abstract Impaired insulin secretion plays a major role in the pathogenesis of type 2 diabetes mellitus, and progressive loss of β-cell function is a pathophysiologic hallmark of type 2 diabetes. Recent science has elaborated on the role of the incretin hormones on β-cell function and insulin secretion, as well as the role that incretin-based pharmacotherapies may have on glycemic control and β-cell function, possibly altering the progressive loss of β-cell function and possibly reversing/halting disease progression. However, incretin-based therapies may also have benefits extending beyond glycemic control and insulin secretion. In this review we examine some of those “beyond-glycemic” benefits, including presentation of data on weight reduction, blood pressure lowering, beneficial changes in the lipid profile, and improvements in myocardial and endothelial function. We investigate how those effects may help ameliorate the cardiovascular burden in patients with diabetes.
Combined effects of recovery period and stimulus intensity on the human auditory evoked vertex response.

Averaged auditory evoked vertex responses were obtained from eight normal-hearing subjects in response to 32 monaural 1000-Hz tone bursts at 30 combinations of recovery period and stimulus intensit...
Hydrotreating the bitumen-derived hydrocarbon liquid produced in a fluidized-bed pyrolysis reactor

Abstract The pyrolysis of bitumen-impregnated sandstone produces three primary product streams: C 1 C 4 hydrocarbon gases, a C 5 + total liquid product, and a carbonaceous residue on the spent sand. The bitumen-derived hydrocarbon liquid was significantly upgraded relative to the native bitumen: it had a higher API gravity, lower Conradson carbon residue, asphaltene content, pour point and viscosity, and a reduced distillation endpoint relative to the native bitumen. The elemental composition was little different from that of the native bitumen except for the hydrogen content, which was lower. Thus, integration of the bitumen-derived liquid into a refinery feedstock slate would require that it be hydrotreated to reduce the nitrogen and sulphur heteratom concentrations and to raise the atomic hydrogen-to-carbon ratio. The bitumen-derived liquid produced in a fluidized-bed reactor (diameter 10.2 cm) from the Whiterocks tar sand deposit has been hydrotreated in a fixed-bed reactor to determine the extent of upgrading as a function of process operating variables. The process variables investigated included total reactor pressure (11.0–17.2 MPa (1600–2500 psig)); reactor temperature (617–680 K; (650–765 °F)) and liquid hourly space velocity (0.18-0.77 h −1 ). The hydrogen/oil ratio was fixed in all experiments at 890 m 3 m −3 (5000 scf H 2 /bbl). A sulphided Ni-Mo on alumina hydrodenitrogenation catalyst was used in these studies. The extent of denitrogenation and desulphurization of the bitumen-derived liquid was used to monitor catalyst activity as a function of process operating variables and to estimate the extent of catalyst deactivation as a function of time on-stream. The apparent kinetics for the nitrogen and sulphur removal reactions were determined. Product distribution and yield data were also obtained.
Retinal Vascular Changes in Retrograde Optic Atrophy

Five patients with unilateral optic atrophy of extraocular origin had a normal retinal vasculature. Clinical examination of the patients included color fundus photographs and fluorescein angiography. After comparing the blood vessels in the blind eye with those in the normal fellow eye, we concluded that vascular attenuation is neither invariably associated with optic atrophy, nor solely caused by decreased local oxygen demand in the retina.
Changes in human serum dopamine-β-hydroxylase activity in various physiological and pathological states

Publisher Summary This chapter discusses the changes in human serum dopamine-β-hydroxylase activity in various physiological and pathological states. Dopamine-β-hydroxylase catalyses the β-hydroxylation of dopamine to norepinephrine; DβH is localized in the chromaffin granules of the adrenal medulla, and storage vesicles of sympathetic nerves. Serum DβH activity and urinary catecholamine levels were monitored in 20 children with active neuroblastoma and 11 patients with inactive or cured disease. Serum DβH activity was elevated in 9 of 20 active cases. In these patients, urinary catecholamine excretion was characterized by abnormal levels of NE and vanillylmandelic acid (VMA). No correlation of serum DβH activity and DA or homovanillic acid was apparent. It is found that serum DβH levels paralleled the catecholamine secretory processes of the active tumor. High serum DβH activity was also observed in 6 of 10 cured patients. A significant number of patients had low enzyme activity whereas others exhibited high enzyme activity. Reduced serum DβH activity could reflect reduced peripheral sympathetic activity.
Vibrational control of nonlinear time lag systems: vibrational stabilization and transient behavior

Abstract This paper addresses two problems of control of nonlinear time lag systems: (i) an existence and a synthesis of parametric vibrations for their stabilization and (ii) the transient behavior analysis of the vibrationally controlled nonlinear systems with time lags. In this work, stabilizability conditions for two vibration types are formulated and procedures for the synthesis of the corresponding stabilizing vibrations are proposed. The method for the transient behavior analysis of vibrationally controlled systems on a finite time interval is developed as well. Several examples are given to support the theory presented.
Infectious Disease Modeling of Social Contagion in Networks

Many behavioral phenomena have been found to spread interpersonally through social networks, in a manner similar to infectious diseases. An important difference between social contagion and traditional infectious diseases, however, is that behavioral phenomena can be acquired by non-social mechanisms as well as through social transmission. We introduce a novel theoretical framework for studying these phenomena (the SISa model) by adapting a classic disease model to include the possibility for ‘automatic’ (or ‘spontaneous’) non-social infection. We provide an example of the use of this framework by examining the spread of obesity in the Framingham Heart Study Network. The interaction assumptions of the model are validated using longitudinal network transmission data. We find that the current rate of becoming obese is 2 per year and increases by 0.5 percentage points for each obese social contact. The rate of recovering from obesity is 4 per year, and does not depend on the number of non-obese contacts. The model predicts a long-term obesity prevalence of approximately 42, and can be used to evaluate the effect of different interventions on steady-state obesity. Model predictions quantitatively reproduce the actual historical time course for the prevalence of obesity. We find that since the 1970s, the rate of recovery from obesity has remained relatively constant, while the rates of both spontaneous infection and transmission have steadily increased over time. This suggests that the obesity epidemic may be driven by increasing rates of becoming obese, both spontaneously and transmissively, rather than by decreasing rates of losing weight. A key feature of the SISa model is its ability to characterize the relative importance of social transmission by quantitatively comparing rates of spontaneous versus contagious infection. It provides a theoretical framework for studying the interpersonal spread of any state that may also arise spontaneously, such as emotions, behaviors, health states, ideas or diseases with reservoirs.
Competing interactions among supramolecular structures on surfaces

A simple model was constructed to describe the polar ordering of non-centrosymmetric supramolecular aggregates formed by self assembling triblock rodcoil polymers. The aggregates are modeled as dipoles in a lattice with an Ising-like penalty associated with reversing the orientation of nearest neighbor dipoles. The choice of the potentials is based on experimental results and structural features of the supramolecular objects. For films of finite thickness, we find a periodic structure along an arbitrary direction perpendicular to the substrate normal, where the repeat unit is composed of two equal width domains with dipole up and dipole down configuration. When a short range interaction between the surface and the dipoles is included the balance between the up and down dipole domains is broken. Our results suggest that due to surface effects, films of finite thickness have a none zero macroscopic polarization, and that the polarization per unit volume appears to be a function of film thickness.
Algebraic invariants for crystallographic defects in cellular automata

Let ${\mathcal{A}}^{{\mathbb{Z}}^D}$ be the Cantor space of ${\mathbb{Z}}^D$-indexed configurations in a finite alphabet ${\mathcal{A}}$, and let $\sigma$ be the ${\mathbb{Z}}^D$-action of shifts on ${\mathcal{A}}^{{\mathbb{Z}}^D}$. A cellular automaton is a continuous, $\sigma$-commuting self-map $\Phi$ of ${\mathcal{A}}^{{\mathbb{Z}}^D}$, and a $\Phi$-invariant subshift is a closed, $(\Phi,\sigma)$-invariant subset ${\mathfrak{A}}\subset{\mathcal{A}}^{{\mathbb{Z}}^D}$. Suppose that ${\mathbf{a}}\in{\mathcal{A}}^{{\mathbb{Z}}^D}$ is ${\mathfrak{A}}$-admissible everywhere except for some small region that we call a defect. It has been empirically observed that such defects persist under iteration of $\Phi$, and often propagate like ?particles? which coalesce or annihilate on contact. We construct algebraic invariants for these defects, which explain their persistence under $\Phi$, and partly explain the outcomes of their collisions. Some invariants are based on the cocycles of multidimensional subshifts; others arise from the higher-dimensional (co)homology/homotopy groups for subshifts, obtained by generalizing the Conway?Lagarias tiling groups and the Geller?Propp fundamental group.
Optimization of trust system placement for power grid security and compartmentalization

This article proposes a robust mathematical method to strategically place trust nodes to compartmentalize a time-critical SCADA network. The trust nodes combine firewall and intrusion detection technology to provide communication network security for protection, control, and SCADA systems. The mathematical technique optimizes the placement of the trust nodes based on the timing requirements of existing systems and the number of trust nodes that are available in the system given constraints, which may arise due to budgetary limitations or the restrictions of existing utility hardware. The intent is to create a planning tool to allow utility system operators to determine the best locations to place trust nodes to increase system security given limited resources and/or hardware constraints. The operational requirements of the environment are translated into a mathematical model. Mixed integer linear programming is used to process this model in search of an optimal solution. Because the problem is provably NP-Hard, a heuristic is also given to quickly find good, but not optimal, solutions. Experiments show promise for the proposed techniques.
Prenatal cocaine use associated with down regulation of receptors in human placenta

Abstract Cocaine use during pregnancy has been associated with abruptio placentae and spontaneous abortions. These effects may be secondary to the vasoconstrictive effects of cocaine or to other alterations. Since it has been demonstrated that the use of opiates during pregnancy alters placental receptors, the effects of cocaine on placental receptors was studied. Women who used cocaine during pregnancy showed a significant lowering of the total number of beta-adrenergic receptor binding sites, mu-opiate receptor binding sites and delta-opiate receptor binding sites. The decreases in Bmax for each of these receptors was not associated with a decrease in the KD. The potential causes for the receptor down regulation and effects are discussed.
Metal-insulator transition in Hubbard-like models with random hopping

An instability of a diffusive Fermi liquid, indicative of a metal-insulator transition (expected to be of first order), arising solely from the competition between quenched disorder and short-ranged interparticle interactions is identified in Hubbard-like models for spinless fermions, subject to (complex) random hopping at half-filling on bipartite lattices. The instability, found within a Finkel'stein Non-Linear Sigma Model treatment in d = (2 + epsilon) > 2 dimensions, originates from an underlying particle-hole like (so-called "chiral") symmetry, shared by both disorder and interactions. In the clean, interacting Fermi liquid this symmetry is responsible for the (completely different) "nesting" instability.