cssi/SciSciGPT-SciSciNet huggingface dataset:
SHAPES AND ALIGNMENTS OF GALAXY CLUSTER HALOS

We present distribution functions and mark correlations of the shapes of massive dark matter halos derived from Hubble volume simulations of a ?CDM universe. We measure both position and velocity shapes within spheres that encompass a mean density 200 times the critical value and calibrate small-N systematic errors using Poisson realizations of isothermal spheres and higher resolution simulations. For halos more massive than 3 ? 1014 h-1 M?, the shape distribution function peaks at (minor/major, intermediate/major) axial ratios of (0.64, 0.76) in position and is rounder in velocity, peaking at (0.72, 0.82). Halo shapes are rounder at lower mass and/or redshift; the mean minor-axis ratio in position follows c/a(M,z) = c15,0[1 - ? ln(M/1015 h-1 M?)](1 + z)-, with c15,0 = 0.631 ? 0.001, ? = 0.023 ? 0.002, and = 0.086 ? 0.004. Position and velocity principal axes are well aligned in direction, with median alignment angle 22?, and the axial ratios in these spaces are correlated in magnitude. We investigate mark correlations of halo pair orientations using two measures: a simple scalar product shows ?1% alignment extending to 30 h-1 Mpc, while a filamentary statistic exhibits nonrandom alignment extending to scales ~200 h-1 Mpc, 10 times the sample two-point correlation length and well into the regime of negative two-point correlation. Shapes of cluster halos are little affected by the large-scale environment; the distribution of supercluster member minor-axis ratios differs from that of the general population at only the few percent level.
Genome editing in human pluripotent stem cells

Genome editing is used to make targeted modifications to the genome of eukaryotic cells. There are many potential applications of genome editing in human pluripotent stem cells (hPSCs) including the generation of knockout and reporter cell lines. This protocol describes a system for efficient genome editing in hPSCs using engineered transcription activator-like effector nucleases (TALENs) or clustered regularly interspaced short palindromic repeat (CRISPR) technology.
Cognitive-Behavioral Conceptualization and Treatment of Anger.

Abstract Anger is conceptualized within a broad cognitive-behavioral (CBT) framework emphasizing triggering events; the person's pre-anger state, including temporary conditions and more enduring cognitive and familial/cultural processes; primary and secondary appraisal processes; the anger experience/response (cognitive, emotional, and physiological components); anger-related behavioral/expressive components; and anger-related outcomes and consequences. Functional/adaptive and dysfunctional/maladaptive anger are briefly discussed along with assessment strategies. Several change-oriented CBT interventions for clients who identify anger as a personal problem and seek therapy for anger reduction are outlined. Many angry clients, however, are not at a change-oriented stage of readiness. For such clients, strategies for increasing readiness and attending to the therapeutic alliance with angry clients are outlined. These principles and strategies are then applied to the case study.
Two-dimensional electrons occupying multiple valleys in AlAs

Two-dimensional electrons in AlAs quantum wells occupy multiple conduction-band minima at the X-points of the Brillouin zone. These valleys have large effective mass and g -factor compared to the standard GaAs electrons, and are also highly anisotropic. With proper choice of well width and by applying symmetry-breaking strain in the plane, one can control the occupation of different valleys thus rendering a system with tuneable effective mass, g -factor, Fermi contour anisotropy, and valley degeneracy. Here we review some of the rich physics that this system has allowed us to explore. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
Variations on R. Schwartz’s Inequality for the Schwarzian Derivative

R. Schwartz’s inequality provides an upper bound for the Schwarzian derivative of a parameterization of a circle in the complex plane and on the potential of Hill’s equation with coexisting periodic solutions. We prove a discrete version of this inequality and obtain a version of the planar Blaschke–Santalo inequality for not necessarily convex polygons. In the proof, we use some formulas from the theory of frieze patterns. We consider a centro-affine analog of Lukő’s inequality for the average squared length of a chord subtending a fixed arc length of a curve—the role of the squared length played by the area—and prove that the central ellipses are local minima of the respective functionals on the space of star-shaped centrally symmetric curves. We conjecture that the central ellipses are global minima. In an appendix, we relate the Blaschke–Santalo and Mahler inequalities with the asymptotic dynamics of outer billiards at infinity.
Distribution Functions for Random Variables for Ensembles of Positive Hermitian Matrices

Distribution functions for random variables that depend on a parameter are computed asymptotically for ensembles of positive Hermitian matrices. The inverse Fourier transform of the distribution is shown to be a Fredholm determinant of a certain operator that is an analogue of a Wiener-Hopf operator. The asymptotic formula shows that, up to the terms of order o(1), the distributions are Gaussian.
Laser-induced diode linking for wafer-scale integration

Diodes formed by ion implantation and diffusion in a conventional CMOS process are positioned such that when desired they may be used to obtain an electrical link between two otherwise separate sections of the integrated circuit. Electrical connections so obtained enable the realization of wafer-scale ICs as demonstrated in recent applications. They theory of laser-beam application to silicon is discussed and it is shown how the various beam and substrate parameters effect the properties of the diode links. Particular attention is paid to the important issue of the reflectivity from the composite system. Careful analytical examinations of the resulting molten zone properties have been performed to fully qualify the use of laser radiation in this technology. Both scanning electron microscopy and secondary-ion mass spectrometry were used to examine such parameters as the lateral and in-depth extension of the molten zone. In addition, electrical measurements were carried out. The results for the various observables compare well with the theoretical predictions. >
Optimal Predictions in Everyday Cognition: The Wisdom of Individuals or Crowds?

Griffiths and Tenenbaum (2006) asked individuals to make predictions about the duration or extent of everyday events (e.g., cake baking times), and reported that predictions were optimal, employing Bayesian inference based on veridical prior distributions. Although the predictions conformed strikingly to statistics of the world, they reflect averages over many individuals. On the conjecture that the accuracy of the group response is chiefly a consequence of aggregating across individuals, we constructed simple, heuristic approximations to the Bayesian model premised on the hypothesis that individuals have access merely to a sample of k instances drawn from the relevant distribution. The accuracy of the group response reported by Griffiths and Tenenbaum could be accounted for by supposing that individuals each utilize only two instances. Moreover, the variability of the group data is more consistent with this small-sample hypothesis than with the hypothesis that people utilize veridical or nearly veridical representations of the underlying prior distributions. Our analyses lead to a qualitatively different view of how individuals reason from past experience than the view espoused by Griffiths and Tenenbaum.
A schlichtness theorem for envelopes of holomorphy

Let Ω be a domain in Open image in new window. We prove the following theorem. If the envelope of holomorphy of Ω is schlicht over Ω, then the envelope is in fact schlicht. We provide examples showing that the conclusion of the theorem does not hold in Open image in new window, n>2. Additionally, we show that the theorem cannot be generalized to provide information about domains in Open image in new window whose envelopes are multiply sheeted.
Credibility battles in the autism litigation

That vaccines do not cause autism is now a widely accepted proposition, though a few dissenters remain. An 8-year court process in the US federal vaccine injury compensation court ended in 2010 with rulings that autism was not an adverse reaction to vaccination. There were two sets of trials: one against the measles-mumps-rubella (MMR) vaccine and one against the mercury-based preservative thimerosal. The MMR story is more widely known because of publicity surrounding the main proponent of an MMR-autism link, British doctor Andrew Wakefield, but the story of thimerosal in court is largely untold. This study examines the credibility battles and boundary work in the two cases, illuminating the sustaining world of alternative science that supported the parents, lawyers, researchers, and expert witnesses against vaccines. After the loss in court, the families and their advocates transformed their scientific arguments into an indictment of procedural injustice in the vaccine court. I argue that the very efforts designed to produce legitimacy in this type of lopsided dispute will be counter-mobilized as evidence of injustice, helping us understand why settling a scientific controversy in court does not necessarily mean changing anyone's mind.
The clinical significance of thrombocytosis in women presenting with a pelvic mass

Objectives : We attempted to determine the clinical usefulness of a preoperative platelet count for predicting malignancy in patients presenting with a pelvic mass. Additionally, in patients in whom a preoperative serum CA 125 level was also determined, the clinical usefulness was compared. Study design : A retrospective review of charts of 241 patients presenting with a pelvic mass was carried out. The patients were then divided by pathologic diagnosis into group 1, benign disease ( n = 102), and group 2, invasive ( n = 121) or borderline ( n = 78) malignancies. Thrombocytosis (platelet count >400,000/(µl) was present in 16% ( n = 16) of patients in group 1 and in 56% ( n = 78) of patients in group 2 ( p 35 U/ml) occurred in 14% ( n = 8) of group 1 and in 81% ( n = 60) of group 2 ( p 2 test was used to analyze results of data. Results : Statistically significant differences in preoperative platelet count and serum CA 125 values were found between group 1 and group 2 patients. The specificity and positive predictive value for thrombocytosis (84% and 83%) compared well with those for serum CA 125 (86% and 88%). The combined use of the tests resulted in specificity of 96% and positive predictive value of 95%. Conclusions : Preoperative platelet count is a test that is rapidly available and easily obtained. The test results may be of value in planning the original management of women presenting with a pelvic mass.
Whose money is it anyway? Ingroups and distributive behavior

Abstract Price theory is often used to explain reactions to rebates and subsidies that are meant to encourage charitable giving. This paper describes the results of a laboratory experiment that tests standard price theory alongside an alternative perspective based on research on the perceptions and behavior of ingroups. Using a modified dictator game, we find that rebates that decrease the price of giving only increase amounts given when they are exogenously funded by the experimenters. When rebates are funded by members of one's group, the decreased price of giving does not lead to increased amounts given. The result suggests that the presence of an ingroup mentality can mediate the relationship between giving and price.
AMSB and the logic of spontaneous SUSY breaking

A cardinal principle of any theory of spontaneous $ \left( {\mathcal{N}=1} \right) $ supersymmetry breaking, is that the order parameter is a linear combination of the F and D terms. Also as long as the supersymmetry of the action is preserved at the quantum level, this principle should be valid after the appropriate corrections are incorporated into the Kahler potential, the superpotential, and the gauge coupling functions that define the theory. The claim that in AMSB there is an extra term for the gaugino mass that is proportional to the gravitino mass, is then equivalent to the statement that quantum effects cause an explicit breaking of (local) SUSY. Expanding on previous work, we argue that this arises from confusing the scalar compensator with the density compensator. We also comment on various recent papers on AMSB.
Reduced order models for control of fluids using the Eigensystem Realization Algorithm

As sensors and flow control actuators become smaller, cheaper, and more pervasive, the use of feedback control to manipulate the details of fluid flows becomes increasingly attractive. One of the challenges is to develop mathematical models that describe the fluid physics relevant to the task at hand, while neglecting irrelevant details of the flow in order to remain computationally tractable. A number of techniques are presently used to develop such reduced-order models, such as proper orthogonal decomposition (POD), and approximate snapshot-based balanced truncation, also known as balanced POD. Each method has its strengths and weaknesses: for instance, POD models can behave unpredictably and perform poorly, but they can be computed directly from experimental data; approximate balanced truncation often produces vastly superior models to POD, but requires data from adjoint simulations, and thus cannot be applied to experimental data. In this article, we show that using the Eigensystem Realization Algorithm (ERA) (Juang and Pappa, J Guid Control Dyn 8(5):620–627, 1985) one can theoretically obtain exactly the same reduced-order models as by balanced POD. Moreover, the models can be obtained directly from experimental data, without the use of adjoint information. The algorithm can also substantially improve computational efficiency when forming reduced-order models from simulation data. If adjoint information is available, then balanced POD has some advantages over ERA: for instance, it produces modes that are useful for multiple purposes, and the method has been generalized to unstable systems. We also present a modified ERA procedure that produces modes without adjoint information, but for this procedure, the resulting models are not balanced, and do not perform as well in examples. We present a detailed comparison of the methods, and illustrate them on an example of the flow past an inclined flat plate at a low Reynolds number.
Additionality of debt relief and debt forgiveness, and implications for future volumes of official assistance

Abstract This paper examines the impact of debt forgiveness and debt relief on official development assistance. From the recipient side, the results from the econometric analysis suggest that countries that received debt relief also received more aid compared to those that did not qualify for debt relief. From the donor side, while the data indicate a decline in aid disbursement since the early 1990s, there is no econometric evidence for a direct causal relationship between the decline in aid and debt relief/forgiveness. Nonetheless, the decline in aid raises serious concerns given that developing countries' need in external resources cannot be met by debt relief alone.
IceHEP high energy physics at the South Pole

Abstract With the solar and SN87 neutrino observations as proofs of concepts, the kilometer-scale neutrino experiment IceCube will scrutinize its data for new particle physics. In this paper, we review the prospects for the realization of such a program. We begin with a short overview of the detector response and discuss the reach of “beam” luminosity. After that we discuss the potential of IceCube to probe deviations of neutrino-nucleon cross-sections from the Standard Model predictions at center-of-mass energies well beyond those accessible in man-made accelerators. Then we review the prospects for extremely long-baseline analyses and discuss the sensitivity to measure tiny deviations of the flavor mixing angle, expected to be induced by quantum gravity effects. Finally, we discuss the potential to uncover annihilation of dark matter particles gravitationally trapped at the center of the Sun, as well as processes occurring in the early Universe at energies close to the Grand Unification scale.
Forecasting exchange rates out-of-sample with panel methods and real-time data

Abstract This paper evaluates out-of-sample exchange rate forecasting with Purchasing Power Parity (PPP) and Taylor rule fundamentals for 9 OECD countries vis-a-vis the U.S. dollar over the period from 1973:Q1 to 2009:Q1 at short and long horizons. In contrast with previous work, which reports “forecasts” using revised data, I construct a quarterly real-time dataset that incorporates only the information available to market participants when the forecasts were made. Using bootstrapped out-of-sample test statistics, the exchange rate model with Taylor rule fundamentals performs better at the one-quarter horizon and panel estimation is not able to improve its performance. The PPP model, however, forecasts better at the 16-quarter horizon and its performance increases in panel framework. The results are in accord with previous research on PPP and Taylor rule models.
Some local-global non-vanishing results for theta lifts from orthogonal groups

We, firstly, improve a theorem of B. Roberts which characterizes non-vanishing of a global theta lift from O(X) to Sp(n) in terms of non-vanishing of local theta lifts. In particular, we will remove all the archimedean conditions imposed upon his theorem. Sec- ondly, following Roberts, we will apply our theorem to theta lifting of low rank similitude groups. Namely we characterize the non-vanishing condition of a global theta lift from GO(4) to GSp(2) in our improved setting. Also we consider non-vanishing conditions of a global theta lift from GO(4) to GSp(1) and explicitly compute the lift when it exists.
Neutrino Experiments: Status, Recent Progress, and Prospects

Neutrino physics has seen an explosion of activity and new results in the last decade. In this report the current state of the field is summarized, with a particular focus on progress in the last two years. Prospects for the near term (roughly 5 years) are also described.
Message Path Delays in Packet-Switching Communication Networks

A communication path (in isolation) in a packet-switching store-and-forward communication network, such as a computer or satellite-communication network, is considered. Messages are assumed to arrive according to a Poisson stream, and messagelengths are considered to be random variables governed by an arbitrary distribution. Message lengths are divided into fixed-length packets which are sent independently over the N -channel communication path in a store-and-forward manner, and are reassembled at the destination terminal. Expressions for the distributions of the message waiting and delay times over the path are derived. Also, we obtain the limiting average message waiting times and required buffer sizes at the individual channels. The overall message waiting time is observed to depend only on the minimal channel capacity. The case of exponentially distributed message lengths serves as an illustrating example.
Optimistic synchronization-based state-space reduction

Reductions that aggregate fine-grained transitions into coarser transitions can significantly reduce the cost of automated verification, by reducing the size of the state space. We propose a reduction that can exploit common synchronization disciplines, such as the use of mutual exclusion for accesses to shared data structures. Exploiting them using traditional reduction theorems requires checking that the discipline is followed in the original (i.e., unreduced) system. That check can be prohibitively expensive. This paper presents a reduction that instead requires checking whether the discipline is followed in the reduced system. This check may be much cheaper, because the reachable state space is smaller.
Wound Infection: A Failure of Wound Healing Caused by an Imbalance of Bacteria

Infection in a wound, like infection elsewhere in the body, is a manifestation of a disturbed host-bacteria equilibrium in favor of the bacteria. This not only elicits a systemic septic response but actually inhibits the multiple processes involved in the wound healing scheme. Each process involved in healing is affected when bacteria proliferate in a wound. Wound infection, whether in an intentional operative incision, an acute traumatic laceration, or a chronic pressure ulcer, results when bacteria indigenous to the patient or exogenous to the wound achieve dominance over the systemic and local factors of host resistance. To be able to prevent and manage wound infections requires an understanding of how each prophylactic or therapeutic maneuver works to maintain or re-establish the bacteria-host balance. Only when this equilibrium is in balance can the normal processes of wound healing proceed to give a satisfactory healing trajectory.
SmartPark shock absorbers for wind farms

Summary form only given. Vehicle-to-grid power transactions will be integrated in future smart grids. This letter presents the novel idea of utilizing plug-in vehicle parking lots (SmartParks) to reduce the shock on the transmission lines connected to a wind farm caused by drastic variations in wind-power generation and to prevent the neighboring lines from overloading. The idea is demonstrated on a power system consisting of a large wind farm and six SmartParksmodeled on a real-time simulator.
Spectroscopy of Four Cataclysmic Variables with Periods above 7 Hours

We present spectroscopy of four cataclysmic variables. Using radial velocity measurements, we find orbital periods Porb for the first time: for GY Hya, 0.347230(9) days, for SDSS J204448045929, 1.68(1) days, for V392 Hya, 0.324952(5) days, and for RX J1951.73716, 0.492(1) days. We also detect the spectra of the secondary stars, estimate their spectral types, and derive distances based on surface brightness and Roche lobe constraints.
Microscopic image analysis of defect areas in optical disks

This paper presents techniques developed at the Information Technology Laboratory of the U.S. National Institute of Standards and Technology (NIST/ITL) for enabling microscopic image analysis of optical data storage media such as optical disks. These non-destructive techniques allow investigators to easily locate on the media a pre-existing series of media defects. These techniques can be applied to any type of optical disks including CDs and DVDs. The paper describes the experimental setup and the techniques utilized to achieve localization and registration of media defects. These techniques include data acquisition, computer control, auto focus, image processing, and remote control and observation. An extension of this setup utilizing available graphical programming environments can allow investigators at different locations to share and discuss the information on media defects by use of the Internet.
Usefulness of Transonic Model Static Data in Predicting Flight Abrupt-Wing-Stall

An approach is provided to answer the question of whether one can rely solely on static data taken during a transonic model test to provide the certainty needed that a new aircraft will or will not have abrupt wing stall (AWS) events during its flight operations. By the comparison of traditional static figures of merit (FOMs) with the free-to-roll (FTR) response data, a rational basis for assessing the merits of using standard testing techniques for the prediction of AWS events has been established. With use of the FTR response data as a standard, because these results compare well with flight, it is concluded that traditional FOMs can not be trusted to provide an indication as to whether a configuration will or will not have AWS tendencies. Even though these FOMs may flag features that have a high degree of correlation with the FTR response data, there are as many or more of these FOM flagged features that do not correlate. Thus, one needs to use the FTR rig to assess AWS tendencies on new configurations.
A new probabilistic routing algorithm for packet-switched computer networks

A probabilistic method is proposed for message routing in packet-switched computer networks with distributed control. The routing table associated with each node consists of path entries, instead of branch entries as found in most routing schemes. Packets are assigned with different paths on a probabilistic basis. The path selection is entirely processed at the source node. The routing table is updated dynamically with change of packet-generating rates at all nodes. We introduce a new quantitative measure, path capacity, to model each path as an M/M/1 queue. With the path capacities, routing tables are updated frequently to achieve balanced minimum delays among all paths. The update overhead is a constant, independent of the size of the network. Both analytical and simulation results are presented and compared with the new ARPANET routing method under various traffic conditions. This probabilistic, path-directed routing algorithm performs significantly better than the new ARPANET routing method under moderate and heavy traffic conditions. Under very light traffic conditions, the two methods have almost equal performance. This method can be applied to improve packet routing in any computer communications networks with distributed control.
Entrainment and chaos in a pulse-driven hodgkin-huxley oscillator

The Hodgkin--Huxley model describes action potential generation in certain types of neurons and is a standard model for conductance-based, excitable cells. Following the early work of Winfree and Best, this paper explores the response of a spontaneously spiking Hodgkin--Huxley neuron model to a periodic pulsatile drive. The response as a function of drive period and amplitude is systematically characterized. A wide range of qualitatively distinct responses are found, including entrainment to the input pulse train and persistent chaos. These observations are consistent with a theory of kicked oscillators developed by Q. Wang and L.-S. Young. In addition to general features predicted by Wang--Young theory, it is found that most combinations of drive period and amplitude lead to entrainment instead of chaos. This preference for entrainment over chaos is explained by the structure of the Hodgkin--Huxley phase-resetting curve.
Simultaneous measurements of velocity, temperature, and pressure using rapid CW wavelength-modulation laser-induced fluorescence of OH

In high speed flows, laser induced fluorescence (LIF) on Doppler shifted transitions is an attractive technique for velocity measurement. LIF velocimetry was applied to combined single-point measurements of velocity, temperature, and pressure and 2-D imaging of velocity and pressure. Prior to recent research using NO, LIF velocimetry in combustion related flows relied largely on the use of seed molecules. Simultaneous, single-point LIF measurements is reported of velocity, temperature, and pressure using the naturally occurring combustion species OH. This experiment is an extension of earlier research in which a modified ring dye laser was used to make time resolved temperature measurements behind reflected shock waves by using OH absorption an in postflame gases by using OH LIF. A pair of fused-silica rhombs mounted on a single galvanonmeter in an intracavity-doubled Spectra-Physics 380 ring laser permit the UV output to be swept continuously over a few wave numbers at an effective frequency of 3kHz.
Testing and Valuing Dynamic Correlations for Asset Allocation

We evaluate alternative models of variances and correlations with an economic loss function. We construct portfolios to minimize predicted variance subject to a required return. It is shown that the realized volatility is smallest for the correctly specified covariance matrix for any vector of expected returns. A test of relative performance of two covariance matrices is based on work of Diebold and Mariano. The method is applied to stocks and bonds and then to highly correlated assets. On average, dynamically correct correlations are worth around 60 basis points in annualized terms, but on some days they may be worth hundreds.
Far-wake behavior of hypersonic blunted cones.

Schlieren techniques have been used in a free-flight range study of the far wake of hypersonic cones. The distance required for viscous wake turbulence to break through the inviscid wake was measured for a variety of cone bluntness ratios, and these were compared with previous measurements using hypersonic spheres. At low Reynolds numbers, the breakthrough distances were found to be much more sensitive to changes in Reynolds number for the bluntest bodies than for those with the least bluntness. This difference was attributed to the effects of viscous wake damping by the action of viscosity, effects that should be more pronounced for blunt bodies. The width of the far wake approached the classical one-third power-law variation with distance and with body-drag coefficient soon after breakthrough.
Terrain-vehicle system evaluation

Abstract The methods used in lunar surface locomotion analysis are applied in a generalized manner to the evaluation of locomotion systems. First, the terrain-vehicle system is described as to mission, operation requirements, environment and vehicle configuration. Cost effectiveness ratio is then considered from several viewpoints. An example is presented of how to evaluate the ability of vehicle configuration to meet military needs.
The Organization of Agriculture: An Epilogue

We might ask, then, why are we concerned with the organization of agriculture? Is concern with the form of agriculture based on an assumed relation to efficiency, distribution, growth, or other economic feature? Or do we have an interest in form as such? If form is important either as a means or an end, do we know enough to influence or re-form agriculture in the "right" direction? For high-income countries, at least, I think that we have been concerned too much with production, too little with distribution, and that, in our view of growth, technology has played God too long. Any reference to the productivity of American agriculture runs the risk of being trite. Perhaps it is best summarized by an analyst of urban affairs, Lyle Fitch, who said, ". . . the agricultural development policy in large part has been a smashing success-American agriculture is the productive miracle of the world."
Observation of a high performance operating regime with small edge-localized modes in the National Spherical Torus Experiment

We report the observation of a high performance scenario in the National Spherical Torus Experiment with very small edge-localized modes (ELMs). These ELMs, individually, have no measurable impact on the stored energy and are observed by several diagnostics. The small ELMs have clear differences as compared with the ELM types reported in the literature, and this operating mode has distinct features compared with other high performance tokamak scenarios with little or no ELMs. The ELM is termed as 'type V', and it has a short-lived n = 1 magnetic precursor oscillation rotating counter to the plasma current and a distinct signature on the soft x-ray system. If we could extrapolate it, this scenario would provide an attractive operating regime for next step fusion experiments.
A Synchronization Technique for Optical PPM Signals

A technique for maintaining synchronization between optical PPM (pulse-position modulation) pulses and a receiver clock by means of a delay-tracking loop is described and analyzed. The tracking loop is driven by a doubly stochastic Poisson process that contains information about the location of the desired slot boundaries. The slot boundaries are subject to slowly varying random delays that are ultimately tracked by the loop. The concept of fractional rms delay error is introduced to quantify the effects of signal and background induced shot noise on the performance of the delay-tracking loop.
Ring Formation in Magnetically Subcritical Clouds and Multiple-Star Formation

We study numerically the ambipolar diffusion-driven evolution of nonrotating, magnetically subcritical, disklike molecular clouds, assuming axisymmetry. Previous similar studies have concentrated on the formation of single magnetically supercritical cores at the cloud center, which collapse to form isolated stars. We show that for a cloud with many Jeans masses and a relatively flat mass distribution near the center, a magnetically supercritical ring is produced instead. The supercritical ring contains a mass well above the Jeans limit. It is expected to break up, through both gravitational and possibly magnetic interchange instabilities, into a number of supercritical dense cores, whose dynamic collapse may give rise to a burst of star formation. Nonaxisymmetric calculations are needed to follow in detail the expected ring fragmentation into multiple cores and the subsequent core evolution. Implications of our results on multiple star formation in general and the northwestern cluster of protostars in the Serpens molecular cloud core in particular are discussed.
Regioselective double Suzuki couplings of 4,5-dibromothiophene-2-carboxaldehyde

Conditions have been identified that enable the one-pot double Suzuki coupling of 4,5-dibromothiophene-2-carboxaldehyde to proceed in good yield. The key to success in these reactions is the use of minimal amounts of water to avoid significant amounts of dehalogenation during the first coupling.
Effect of Pelvic Muscle Exercise on Transient Incontinence During Pregnancy and After Birth

Abstract Objective : To test the effect of pelvic muscle exercise on postpartum symptoms of stress urinary incontinence and pelvic muscle strength in primigravidas during pregnancy and postpartum. Methods : A prospective trial randomized women into treatment (standardized instruction in pelvic muscle exercise) or control (routine care with no systematic pelvic muscle exercise instruction). Urinary incontinence symptoms were measured by questionnaire. Pelvic muscle strength was quantified by an instrumented gynecologic speculum. Time points were 20 and 35 weeks' gestation and 6 weeks, 6 months, and 12 months postpartum. Results : Outcomes are reported for 46 women with vaginal or cesarean birth and for a subsample of 37 women with vaginal birth. Longitudinal analyses are reported for cases with complete data across time points. Diminished urinary incontinence symptoms were seen in the treatment group, with significant treatment effects demonstrated at 35 weeks' gestation ( F [1,43] = 4.36, P = .043), 6 weeks postpartum ( F [1,43] = 4.94, P = .032), and 6 months postpartum ( F [1,43] = 4.29, P = .044). A repeated measures analysis of variance showed a significant interaction between time and treatment for urinary incontinence ( F [4, 41] = 2.83, P = .037). A significant effect of initial pelvic muscle strength was demonstrated; ie, pelvic muscle strength at 20 weeks' gestation predicted significantly 12-months postpartum strength ( F [1, 13] = 8.12, P = .014). Group differences in pelvic muscle strength were observed (the treatment group had greater strength at 6 weeks and at 6 months postpartum than did controls), but these differences were not statistically significant. Conclusion : Practice of pelvic muscle exercise by primiparas results in fewer urinary incontinence symptoms during late pregnancy and postpartum.
Pd–Au bimetallic catalysts: understanding alloy effects from planar models and (supported) nanoparticles

Pd–Au bimetallic catalysts often display enhanced catalytic activities and selectivities compared with Pd-alone catalysts. This enhancement is often caused by two alloy effects, i.e., ensemble and ligand effects. The ensemble effect is a dilution of surface Pd by Au. With increasing surface Au coverage, contiguous Pd ensembles disappear and isolated Pd ensembles form. For certain reactions, for example vinyl acetate synthesis, this effect is responsible for reaction rate enhancement via the formation of highly active surface sites, e.g., isolated Pd pairs. The disappearance of contiguous Pd ensembles also switches off side reactions catalyzed by these sites. This explains the selectivity increase of certain reactions, for example direct H2O2 synthesis. The ligand effects are electronic perturbation of Pd by Au. Via direct charge transfer or by affecting bond lengths, the ligand effects cause the Pd d band to be more filled, moving the d-band center away from the Fermi level. Both changes make Pd more “atomic like” therefore binding reactants and products more weakly. For certain reactions, this eliminates a so-called “self-poisoning” effect and enhances activity/selectivity.
Platensimycin and platencin: promising antibiotics for future application in human medicine

Platensimycin and platencin are novel antibiotics produced by Streptomyces platensis. They are potent and non-toxic natural products active against Gram-positive pathogens, including antibiotic-resistant strains and Mycobacterium tuberculosis. They were isolated using an intriguing target-based whole-cell antisense differential sensitivity assay as inhibitors of fatty acid biosynthesis of type II. This type of biosynthesis is not present in humans. Platensimycin inhibits the elongation-condensing enzyme FabF, whereas platencin inhibits both FabF and FabH. For these antibiotics to become successful drugs, their pharmacokinetics must be improved. They have too high a rate of clearance in the body, yielding a low degree of systematic exposure. They work well when administered by continuous infusion, but this is not a useful method of delivery to patients. The two antibiotics and many analogs have been prepared by chemical synthesis. Natural congeners have also been obtained from the producing actinomycete. However, none of these molecules are as active as platensimycin and platencin. Using tools of rational metabolic engineering, superior strains have been produced making hundreds of times more antibiotic than the natural strains.
A Problem with the Clustering of Recent Measures of the Distance to the Large Magellanic Cloud

The distance to the Large Magellanic Cloud (LMC) has long been of key importance for the distance ladder and the distances to all galaxies, and as such many groups have provided measurements of its distance modulus (μ) with many methods and various means of calibrating each method. Before the year 2001, the many measures spanned a wide range (roughly 18.1 3-sigma probability level. This concentration is a symptom of a worrisome problem. Interpretations considered include correlations between papers, widespread over-estimation of error bars, and band-wagon effects. The purpose of this paper is to alert workers in the field that this is a serious problem that should be addressed.
NATURAL HISTORY OF PITUITARY-ADRENAL RECOVERY FOLLOWING LONG-TERM SUPPRESSION WITH CORTICOSTEROIDS.

Plasma ACTH and 17-hydroxycorticosteroid concentrations were measured at various intervals in patients recovering from prolonged pituitary suppression. Pituitary-adrenal recovery was found to follow a definite pattern requiring several months for completion. Initially, both ACTH and corticosteroid levels were relatively low, a situation similar to that seen in patients with hypopituitarism. Thereafter, plasma ACTH levels gradually increased until they were supernormal, but there was a lag of several months in the recovery of normal adrenal responsiveness. Despite the fact that the pituitary gland could secrete large quantities of ACTH and despite the fact that corticosteroid levels were subnormal, a diurnal rhythm was observed in ACTH levels with a decrease to low values during the latter portion of each day. After several months, corticosteroid levels rose to normal, and soon thereafter plasma ACTH concentrations fell again to normal.
Mixed estimation based on quasi-prior judgments

Abstract The mixed estimation procedure for inference in the linear model is extended to the case in which prior judgments on parameters are correlated with the sample. The discussion includes an application, a test for the compatibility of prior and sample information, and measures for their shares of the posterior precision.
Small 3-Manifolds of Large Genus

We prove the existence of pure braids with arbitrarily many strands which are small, i.e. the complements contain no closed incompressible surface which is not boundary parallel. This implies the existence of irreducible non-Haken 3-manifolds of arbitrarily high Heegaard genus.
Case Studies of Rock Reinforcement Components and Systems Testing

Rock reinforcement is widely used in tunnels and surface and underground mines. A large number of proprietary products are available in various configurations of components. While the mechanical properties of the primary element are available from product brochures, the associated component properties may vary widely and adversely influence the overall performance of the system. Field pull out tests are most commonly used to measure the system response in the toe anchor region. However, the response of the collar region is less commonly considered but may be more important. Several case studies are described in which various components and systems of rock bolts and cable bolts have been subjected to static loading in the laboratory and in the field. The results generally demonstrate the importance of considering the properties of all the components and not simply those of the primary element. In some cases, the internal fixtures have strengths much less than the elements. Often it has also been found that the fixture at the collar has significantly less strength than the element and this will result in complete loss of function in restraining surface support hardware, such as plates, mesh and reinforced shotcrete.
The age of the Milky Way inner halo

Using observations of four nearby white dwarf stars in the Milky Way halo, the age of local-field halo stars is measured to be nearly around 11 billion years. An analysis of almost 2,000 white dwarfs discovered recently in the nearest globular cluster, Messier 4, has shown how useful they are as indicators of the age of a stellar population. White dwarfs, spent remnants of hydrogen stars, are simple structures treading a predictable evolutionary path, so their ages can be accurately estimated. Here, Jason Kaliari reports observations of newly formed white dwarf stars in the halo of the Milky Way. The age of local field halo stars emerges as about 11.4 billion years, much younger than the Milky Way's globular cluster population, the oldest of which formed about 13.5 billion years ago. The Milky Way galaxy has several components, such as the bulge, disk and halo. Unravelling the assembly history of these stellar populations is often restricted because of difficulties in measuring accurate ages for low-mass, hydrogen-burning stars1,2. Unlike these progenitors, white dwarf stars3, the ‘cinders’ of stellar evolution, are remarkably simple objects and their fundamental properties can be measured with little ambiguity4,5. Here I report observations of newly formed white dwarf stars in the halo of the Milky Way, and a separate analysis of archival data in the well studied 12.5-billion-year-old globular cluster Messier 4. I measure the mass distribution of the remnant stars and invert the stellar evolution process to develop a mathematical relation that links this final stellar mass to the mass of their immediate progenitors, and therefore to the age of the parent population. By applying this technique to a small sample of four nearby and kinematically confirmed halo white dwarf stars, I calculate the age of local field halo stars to be 11.4 ± 0.7 billion years. The oldest globular clusters formed 13.5 billion years ago. Future observations of newly formed white dwarf stars in the halo could be used to reduce the uncertainty, and to probe relative differences between the formation times of the youngest globular clusters and the inner halo.
A Fast, Accurate, and Robust Algorithm for Transferring Radiation in Three-dimensional Space

A new algorithm for transferring radiation in three-dimensional space is developed. The algorithm computes radiation sources and sinks using the fast Fourier transform method, based on a formulation in which the integral of any quantity (such as emissivity or opacity) over any volume may be written in the classic convolution form. The algorithm is fast, with the computational time scaling as N(log N)2 (where N is the number of grid points of a simulation box), independent of the number of radiation sources. Furthermore, in this formulation one can naturally account for both local radiation sources and diffuse background as well as any extra external sources, in a self-consistent fashion. Finally, the algorithm is completely stable and robust. While the algorithm is generally applicable, we test it thoroughly on an encompassing set of problems relevant for cosmological applications. Tests show that computed results with the present algorithm are, in all cases, in very good agreement with analytic expectations, where they exist. For a realistic cosmological density field the algorithm is in excellent agreement with a high-resolution ray-tracing method. Specifically, radiation flux is guaranteed to propagate in the right direction, and its distribution is shown to be computed accurately. The ionization fronts travel at the correct speeds, with errors no larger than about one cell for all the cases tested. The total number of photons is conserved in the worst case at a ~10% level and typically at a 1%-5% level over hundreds of time steps. As an added advantage, the accuracy of the results depends weakly on the size of the time step, with a typical cosmological hydrodynamic time step being sufficient.
Quark-hadron duality in electron-pion scattering

We explore the relationship between exclusive and inclusive electromagnetic scattering from the pion, focusing on the transition region at intermediate Q2. Combining Drell-Yan data on the leading twist quark distribution in the pion with a model for the resonance region at large x, we calculate QCD moments of the pion structure function over a range of Q2, and quantify the role of higher twist corrections. Using a parameterization of the pion elastic form factor and phenomenological models for the π↦ρ transition form factor, we further test the extent to which local duality may be valid for the pion.
A competitive kinetics study of the reaction of Cl with CS2 in air at 298 K

The relative rate technique has been used to investigate the kinetics of the reaction of Cl atoms with carbon disulfide, CS2, at 700 Torr total pressure of air at 298 K. The decay rate of CS2 was measured relative to CH4, CH3Cl and CHF2Cl. For experiments using CH4 and CH3Cl references, the decay rate of CS2 was dependent on the ratio of the concentration of the reference to that of CS2. We ascribe this behavior to the generation of OH radicals in the system leading to complicated secondary chemistry. From experiments using CHF2Cl we are able to assign an upper limit of 4 × 10−15 cm3 molecule−1 s−1 for the overall reaction, Cl + CS2 → products.