cssi/SciSciGPT-SciSciNet huggingface dataset:
Thermal conductivity of semiconductor (bismuth–telluride)–semimetal (antimony) superlattice nanostructures

Abstract In the present study, the thermal conductivity of superlattice bismuth–telluride (semiconductor)–antimony (semimetal) (Bi 2 Te 3 –Sb) nanostructures (nanowires and nanotubes) has been modeled using an incoherent particle model, approximating all the scattering to be diffuse and gray, and applying a Matthiessen-type simplification. The effect of varying the ratio of the superlattice nanowire segment lengths ( L ) of Sb and Bi 2 Te 3 has also been studied assuming: (i) L Sb = L Bi 2 Te 3 ; (ii) L Sb = 0.25 × L Bi 2 Te 3 ; (iii) L Sb = 0.5 × L Bi 2 Te 3 ; (iv) L Sb = 2.0 × L Bi 2 Te 3 ; and (v) L Sb = 4.0 × L Bi 2 Te 3 . It is shown that thermal conductivity of the superlattice nanowires reduces either with a reduction of segment lengths ( L Sb and L Bi 2 Te 3 ) or with a reduction of nanowire diameter. Specifically, the thermal conductivity is lower than 2 W m −1 K −1 (the bulk value for Bi 2 Te 3 ), even when the nanowire diameters (10 nm) are 10 times larger than the mean free path (1 nm) of Bi 2 Te 3 , provided the individual segment lengths ( L Sb and L Bi 2 Te 3 ) are lower than the mean free path limit. The thermal conductivity of either superlattice nanowires or superlattice nanotubes was also observed to decrease, as the segment length of semimetal (Sb) is lowered relative to the segment length of semiconductor (Bi 2 Te 3 ). In the case of superlattice nanotubes, a reduction in wall thickness caused a corresponding reduction in thermal conductivity as well. For example, with a fixed outer diameter value of 5 nm, the thermal conductivity of the nanotubes can be lowered by ∼33% by decreasing the tube wall thickness from 0.75 to 0.1 nm. Our predictions also suggest that for a given value of the segment lengths of L Sb and L Bi 2 Te 3 , nanotubes exhibit a lower thermal conductivity than nanowires. This therefore suggests that nanotubes of superlattice structures of Sb and Bi 2 Te 3 should exhibit a higher thermoelectric figure of merit ( ZT ) than nanowires under corresponding conditions.
Universal quantum computation with spin-1/2 pairs and Heisenberg exchange.

An efficient and intuitive framework for universal quantum computation is presented that uses pairs of spin-1/2 particles to form logical qubits and a single physical interaction, Heisenberg exchange, to produce all gate operations. Only two Heisenberg gate operations are required to produce a controlled $\ensuremath{\pi}$-phase shift, compared to nineteen for exchange-only proposals employing three spins. Evolved from well-studied decoherence-free subspaces, this architecture inherits immunity from collective decoherence mechanisms. The simplicity and adaptability of this approach should make it attractive for spin-based quantum computing architectures.
Courtship behaviour of the salamander Desmognathus imitator (Amphibia: Caudata: Plethodontidae)

Courtship in the imitator salamander, Desmognathus imitator, follows a predictable course that appears characteristic for the genus. Three more-or-less consecutive phases are recognized: orientation of the male to the female, persuasion of the female by the male (involving both tactile and chemical stimuli) and indirect sperm transfer by means of a spermatophore. The individual behaviour patterns that comprise courtship in D. imitator are similar to those observed for congeneric species of similar body size, except for "bite-and-seize", which has previously been described only in two dwarf species. Understanding the evolution of courtship in the genus Desmognathus will be greatly facilitated when behavioural characters in all taxa can be optimized onto an independent phylogenetic tree.
Lydia Shattuck: “A Streak of the Modern”

(1991). Lydia Shattuck: “A Streak of the Modern”. Teaching Education: Vol. 3, No. 2, pp. 127-131.
Safe landing planning for an energy-constrained multicopter

As Unmanned Aircraft Systems (UAS) become more prevalent and their commercial application in populated areas becomes technologically feasible, risk mitigation techniques must be developed to minimize the probability of harm to persons and property in the vicinity of the aircraft. This paper presents an algorithm to calculate a safe landing path for a small quadrotor UAS that experiences a low energy condition while flying over a populated area. This approach uses public databases of population distributions, structure locations, and terrain to create a cost map of the operating zone of the UAS offline. The UAS uses this data to quickly identify a safe landing path using an A* search algorithm. Simulation-based case studies are presented of a UAS operating within New York City to illustrate how different cost terms impact optimal path characteristics.
Infrared absorption in K-doped (CH)χ

The infrared absorption of polyacetylene doped with high concentrations of potassium has been studied. The samples, doped by a vapor-phase technique to y~0.08 and y~0.18, showed doping-induced infrared absorption at ~900, 1270, and 1390 cm -1 which was comparable in strength to that seen in [CH(CIO4)y]x with y~0.06. These experiments were motivated by calculations of the infrared absorption which showed that whereas there are only small differences in the infrared spectra for isolated solitons and isolated polarons there is a dramatic difference between the high-concentration polaron lattice and soliton lattice. The shapes of the absorption spectra are rather similar but the absorption for the polaron lattice is 13 orders of magnitude weaker than that of soliton lattice. The observation of these features at high doping levels appears to be inconsistent with the polaronic metal and strongly disordered Peierls insulator models for highly doped polyacetylene. I. Introduction This paper describes a study of the infrared reflectance of (CH)x doped with potassium into the "metallic ~ range. Our experiments were motivated by calculations of the infrared absorption by Hicks and Gammel, 1 Choi and Mele, 2 and Hicks, Gammel, Choi and" Mele, 3 which show that whereas there are only small differences in the infrared spectra for isolated solitons and isolated polnrons (in agreement with the earlier work of Horowitz 4 there is a dramatic difference between the high-concentration polaron lattice and soliton lattice. The shapes of the absorption spectra are rather similar but the absorption for the polaron lattice is 13 orders of magnitude weaker than that of the soliton lattice. It appeared to us that a measurement of the strength of the doping-related infrared absorption at high concentrations should therefore be able to distinguish between these two possibilities.
Echocardiographic recognition of paraseptal structures

Improved echocardiographic equipment provides detailed images of the heart and shows anatomic paraseptal structures previously not well defined. Echocardiograms were analyzed from 33 patients who later underwent cardiac transplantation, and the paraseptal structures noted were correlated with the pathologic specimens. Patterns associated with right ventricular chordae tendineae, the moderator band and the posterior papillary muscle are illustrated. Hypertrophic and fibrotic right ventricular trabeculae and left ventricular paraseptal bands are noted. These structures can be specifically sought and identified using the current generation of echocardiographs, thereby avoiding potential problems of septa) definition and measurement.
Effects of two inhibitors of anion transport on bone resorption in organ culture.

Abstract The present investigation was undertaken to examine the effects of 4-acetamido-4′-isothiocyanostilbene-2,2-disulfonic acid (SITS) and 4,4′-diisothiocyanostilbene-2,2′-disulfonic acid (DIDS), known amino-reactive and selective inhibitors of anion exchange across the plasma membrane, on bone resorption in organ cultures of fetal rat long bones. Cultures were treated with SITS and DIDS under control unstimulated conditions or with PTH. Both SITS and DIDS were found to be potent inhibitors of 45Ca release from previously labeled fetal rat long bones. Both control resorption and the response to PTH were inhibited in a dose-related fashion. SITS and DIDS also inhibited the incorporation of [3H]thymidine in bone. The effects on resorption and [3H]thymidine incorporation were reversible when the drugs were withdrawn. These findings indicate that SITS and DIDS are potent inhibitors of bone resorption which may act by blocking the anion exchange,
B Cell Tolerance: Lessons from Transplantation

Given the ability of the B cell compartment to acquire tolerance to self we cannot explain why spontaneous humoral tolerance does not arise following transplantation. Here we review the fundamental mechanisms of B cell tolerance that operate in development and direct the reader to possible mechanisms that may explain how B cell tolerance fails to develop following transplantation.
Documenting the use of expert scientific reasoning processes by high school physics students

We describe a methodology for identifying evidence for the use of three types of scientific reasoning. In two case studies of high school physics classes, we used this methodology to identify multiple instances of students using analogies, extreme cases, and Gedanken experiments. Previous case studies of expert scientists have indicated that these processes can be central during scientific model construction; here we code for their spontaneous use by students. We document evidence for numerous instances of these forms of reasoning in these classes. Most of these instances were associated with motion- and force-indicating depictive gestures, which we take as one kind of evidence for the use of animated mental imagery. Altogether, this methodology shows promise for use in highlighting the role of nonformal reasoning in student learning and for investigating the possible association of animated mental imagery with scientific reasoning processes.
Significance of intracellular and secreted acid phosphatase enzyme activities, and zinc and calcium interactions, on phosphorus efficiency in wheat, sunflower, chickpea, and lentil cultivars

Phosphorus efficiency (PE), and its relationship with intracellular (APase) and secreted (S-APase) acid phosphatases, anthocyanin accumulation, and calcium and zinc nutrition, were compared among 8 cultivars of each of wheat, sunflower, chickpea, and lentil grown under greenhouse conditions with low and high rates of P supply in a P-deficient calcareous soil. Except for the chickpea cultivars, deficiency of P resulted in significant decreases in shoot dry weight of all the crop cultivars and led to significant decreases in root dry weight in wheat and sunflower, significant increases in root dry weight in chickpea, and no significant difference in root dry weight in lentil. PE differed greatly among species and their cultivars. On average, shoot P concentration in cultivars of wheat, sunflower, chickpea, and lentil increased by 44%, 54%, 47%, and 8%, respectively, with P supply, and the increases in P concentration differed greatly among cultivars of all species. Intracellular leaf APase activity of wheat and lentil cultivars was slightly decreased by P supply, while it was unchanged in sunflower and chickpea cultivars. However, root-secreted acid phosphatase (S-APase) activity was significantly reduced by P supply in wheat, sunflower, and chickpea cultivars. Under low-P conditions, S-APase activities of all species except sunflower were negatively correlated with PE. Phosphorus deficiency increased the anthocyanin concentration of the cultivars of wheat and sunflower, whereas it was usually decreased in cultivars of the P-efficient species chickpea and lentil. In general, concentration of Ca was found to be lower, but Zn concentration was higher, in P-efficient cultivars than in P-inefficient cultivars. The results demonstrated that PE of the cultivars clearly depends on their ability to take up P and Zn, and on secretion of acid phosphatases from their roots under P deficiency. The results also suggest that characteristics of Zn and Ca nutrition should be taken into consideration when screening cultivars of crop species for their P efficiency.
Quiescent SV40 virus transformed 3T3 cells in culture.

Abstract Serum counteracts low nutrient concentrations in the culture medium in SV40 virus transformed 3T3 (SV3T3) cells. The transport of [3H]-leucine into TCA soluble material in SV3T3 cells is stimulated by serum and inhibited by But2-cAMP. When SV3T3 cells are cultured in low leucine concentrations (⪯ 8 × 10−6 M), the cell's morphology is similar to the one of cells incubated in complete medium in the presence of But2-cAMP and cells become quiescent. Cells become arrested throughout the cell cycle. The results suggest that the mechanism by which But2-cAMP inhibits growth of SV3T3 cells is by inhibiting the transport of leucine in SV3T3 cells.
Modulating Pharmacokinetics, Tumor Uptake and Biodistribution by Engineered Nanoparticles

Background Inorganic nanoparticles provide promising tools for biomedical applications including detection, diagnosis and therapy. While surface properties such as charge are expected to play an important role in their in vivo behavior, very little is known how the surface chemistry of nanoparticles influences their pharmacokinetics, tumor uptake, and biodistribution. Method/Principal Findings Using a family of structurally homologous nanoparticles we have investigated how pharmacological properties including tumor uptake and biodistribution are influenced by surface charge using neutral (TEGOH), zwitterionic (Tzwit), negative (TCOOH) and positive (TTMA) nanoparticles. Nanoparticles were injected into mice (normal and athymic) either in the tail vein or into the peritoneum. Conclusion Neutral and zwitterionic nanoparticles demonstrated longer circulation time via both IP and IV administration, whereas negatively and positively charged nanoparticles possessed relatively short half-lives. These pharmacological characteristics were reflected on the tumor uptake and biodistribution of the respective nanoparticles, with enhanced tumor uptake by neutral and zwitterionic nanoparticles via passive targeting.
Experimental study of granular flows in a rough annular shear cell.

The study of granular flows in physics has always been important because of their recurring presence in nature and industry. However, the nonlinear and multiphase behavior exhibited by these particulate systems makes them hard to model and predict. Several experiments were conducted in the past to gain insight into granular flows. The current experimental work furthers this insight and specifically attempts to understand the effect of rough surfaces on granular flows, namely, their local flow behavior. Understanding this interaction can have implications on industrial-scale granular problems. In this work, a granular shear cell, a two-dimensional annular shear cell, was developed to conduct shear experiments where roughness is imposed on the driving surface and experimentally quantified. A digital particle tracking velocimetry data retrieval scheme was developed to extract solid fraction, velocity, and granular temperature data from the experiments as a function of the roughness factor and wheel rotation rate. In general, the steady-state results show the two distinct regions as expected---a high-velocity and dilute-gas-like kinetic region near the moving wall and a high-solid-fraction liquid-like frictional flow regime away from the moving wall. Parametric studies conducted show that the normalized slip near the moving wall decreases with increasing wall roughness and decreasing wall rotation rate. Slip is an important parameter which can be easily interpreted as momentum transfer or traction performance in granular systems related to wheel-terrain interaction, agricultural processing, and most notably granular lubrication.
The legacy of the digital divide Gender, socioeconomic status, and early exposure as predictors of full-spectrum technology use among young adults

This study investigates how college students’ current levels of technology use might be affected by digital divide issues. Survey data were collected from 130 students in colleges of education at two midwestern universities. Factor analysis yielded that students’ uses of technology can be described using three broad categories: entertainment, communication, and construction. Each is important to consider, in that high levels of use across categories indicate a broad base of technology skills. Multiple regression results indicate that male students from higher family income levels who had access to a computer at home before age 10 show significantly higher levels of full-spectrum technology use than other demographic groups. Students’ age of first encounter with computers at school had no significant impact on their full-spectrum technology use. These results have implications for how we address digital divide issues, and the article discusses what may be critical differences between home and school access.
Second phase entrepreneurship: Breaking through the growth wall

Following six steps can help ensure that growth continues in the owner-managed firm. E ntrepreneurs are the heroes of marketdriven economies around the world. They generate and act on new ideas; they are willing to take necessaw risks; and they create jobs at rates that embarrass their largescale corporate counterparts. Entrepreneurs start new" businesses, revitalize old ones, and nurture them to respectability. However, as the energy unleashed by the initial idea and original entrepreneurial impulse dissipates, most of such firms stop growing. Why do so many owner-managed companies fail to escape their initial entrepreneurial phase? In search of the answer, we studied 20 privately held firms that achieved profitable growth during their first 15 years of entrepreneurial life but have failed to grow appreciably since. We then compared their experience to that of six owner-managed firms that were able to sustain growth beyond the initial entrepreneurial phase. What we discovered is that the internally focused conventional explanat ions-inadequate growth capital, exceeding the entrepreneur 's personal span of control, the development of bureaucratic practices, and the loss of entrepreneurial energy-were only minor factors accounting for the growth stall in the Phase One companies. (For purposes of this article, companies that have failed to grow beyond their initial entrepreneurial phase are designated as Phase One companies. Those that have achieved and sustained growth beyond their initial entrepreneurial phase are designated as Phase Two companies.) Instead, the major reason they s topped growing was because, unlike the six Phase Two companies, they failed to understand and respond to the complex set of changing opportunities and obstacles that were developing outside the firm. This article explores the differences between the 20 entrepreneurs who hit the growth wall and the companies that continued successfully into Phase Two. Based on this comparison, I suggest five steps that can help first-phase entrepreneurs grow again, marking a transition into the second phase of development.
Broadening the applicability of endovascular aneurysm repair: the use of iliac conduits.

Abstract Objective: Suboptimal iliac anatomy has sometimes precluded endovascular repair of abdominal aortic aneurysm (AAA). In an effort to increase the applicability of endovascular repair, a limited retroperitoneal approach and iliac conduit was used in some patients with unsuitable iliac anatomy at high risk for open repair. Methods: Charts and imaging studies of 312 patients who underwent endovascular (AAA) repair at the Cleveland Clinic Foundation between June 1999 and November 2000 were reviewed. Among these, 22 patients with complex iliac anatomy had an iliac conduit placed. Seventeen of these procedures were planned, but five were unplanned and placed after an iliac artery injury. A group of 17 patients who underwent a standard endovascular repair without conduits was selected and matched to the 17 patients in the planned conduit group by baseline comorbidities. The conduits were 8-mm or 10-mm polyester grafts sewn proximally to the common iliac artery and provided unobstructed access to the aneurysm. After insertion of the endograft device through the conduit, the distal end of the conduit was anastomosed to the external iliac or common femoral vessels. Results: Operative time and estimated blood loss were higher among patients in whom conduits were performed, especially when performed urgently as an unplanned procedure. Although operative time and intensive care unit and hospital stays were longer for the group of patients with iliac conduits, the cardiac pulmonary and renal complication rates were similar for the conduit and the standard endovascular repair group. Conclusion: The use of a limited retroperitoneal approach and iliac conduit for patients with difficult iliac anatomy increases the applicability of the endovascular repair of AAA. This technique should be considered when an open surgical approach is inadvisable on the basis of medical comorbidities. (J Vasc Surg 2002;36:111-7.)
On the detection of emotional facial expressions: Are girls really better than boys?

One facet of Vigil's socio-relational framework of expressive behaviors (SRFB) suggests that females are more sensitive to facial expressions than are males, and should detect facial expressions more quickly. A re-examination of recent research with children demonstrates that girls do detect various facial expressions more quickly than do boys. Although this provides support for SRFB, further examination of SRFB in children would lend important support this evolutionary-based theory.
Conversational memory employing cued and free recall

This study tests two hypotheses: (a) that cued recall elicits significantly more conversational information than free recall and (b) that conversational interactants recall more of their partner's utterances than their own. Subjects recalled significantly more of their conversation (about five times more in the cued recall than the free recall condition). There was no difference between recall of their own and other comments overall or in the free recall condition. However, subjects in the cued recall condition remembered more of their own than their interactional partner's utterances.
Oversampling of digitized images.

Oversampling is defined as sampling with a device whose characteristic width is greater than the interval between samples. This paper shows why oversampling should be avoided and discusses the limitations in data processing if circumstances dictate that oversampling cannot be circumvented. Principally, oversampling should not be used to provide interpolating data points. Rather, the time spent oversampling should be used to obtain more signal with less relative error, and the Sampling Theorem should be employed to provide any desired interpolated values. The concepts are applicable to single-element and multielement detectors.
Mg-Si-AI-O-N Glasses Prepared By Nitriding Cordierite Powders Derived from Polymer Precursors

We have previously reported the synthesis of cordierite polymer precursors directly from MgO, SiO2 and alumina.1 Removal of organics at 400°C in air and/or in oxygen gave amorphous, atomically mixed, oxide powders with surface areas of 250-400 m2/g. It is possible to convert these high surface area oxide powders to Mg-Si-Al-O-N powders by heating in a flowing NH3 atmosphere. The effects of selected processing conditions on nitrogen incorporation, in a set of well defined oxide powders, were examined. The powders are nitrided in flowing NH3, at temperatures of 700-1200°C, to obtain N contents of up to 5 atomic percent.
Terahertz-field-induced second-harmonic generation measurements of liquid dynamics

Abstract A new third-order non-linear THz pump–optical probe measurement of liquid dynamics is reported. Terahertz-field-induced second-harmonic generation (TFISH) measures the correlations between the hyperpolarizability and dipole moment fluctuations at equilibrium. This method is analyzed in the Born–Oppenheimer approximation, and is shown to measure diffusive orientational dynamics as 〈 P 1 (cos θ )〉. Measurements of water and acetonitrile yield relaxation time constants of 13 and 9.6 ps, respectively. Signals were also obtained from thin polymer films and surfaces, suggesting a number of applications for this method.
Quantity and timing of needlefall in N and P fertilized loblolly pine stands

Needlefall quantity and timing were examined for 1.5 years on three loblolly pine (Pinus taeda L.) stands from a nitrogen (N) and phosphorus (P) fertilization field study. Needlefall biomass increased following N fertilization on the two N-deficient stands. Needlefall biomass increased by as much as 75% (from 2088 to 3660 kg ha−1 year−1) on one of these stands, but on average increases were about 30%. On a high N quality stand, there was no needlefall biomass response to N fertilization. Phosphorus had no effect on needlefall biomass in any of the three stands. Across all stands, needlefall biomass was unrelated to stocking (as measured by basal area), but significantly correlated (r2 = 0.53; P<0.05) with foliar percent N. We hypothesized accelerated needlefall as a result of moisture stress during very dry periods in 1985 and 1986, particularly on plots which increased foliar biomass (and hence needlefall biomass) after N fertilization. Needlefall timing was affected by N fertilization on all stands, including a stand whose foliar biomass did not increase with N fertilization. In most cases, N fertilization resulted in an increased proportion of needlefall in early summer, and a decreased proportion of needlefall in late fall. This pattern suggests that other factors, such as shading or hormonal changes, may also be important in determining needlefall timing on fertilized stands.
Dynamic mechanical properties of polymer melts: The dependence of viscoelastic properties on molecular weight distribution

An investigation of the dynamic mechanical properties of several molten polymers was performed using the Maxwell Orthogonal Rheometer. Relaxation spectra derived from experimental data for the terminal region of viscoelastic response indicate that as molecular weight distribution broadens, terminal relaxation phenomena associated with molecular disentanglement and translation extend over a corresponding wider frequency range. The same data indicate that a true maximum relaxation time beyond which no elastic response is observed exists for the materials studied. Moreover, the maximum relaxation time corresponds to the reciprocal of the frequency where the dynamic viscosity deviates from its zero-shear value. Thus an estimate of the time necessary for complete elastic recovery in polymer melts is readily obtained experimentally.
Evans Function for Lax Operators with Algebraically Decaying Potentials

We study the instability of algebraic solitons for integrable nonlinear equations in one spatial dimension that include modified KdV, focusing NLS, derivative NLS, and massive Thirring equations. We develop the analysis of the Evans function that defines eigenvalues in the corresponding Lax operators with algebraically decaying potentials. The standard Evans function generically has singularities in the essential spectrum, which may include embedded eigenvalues with algebraically decaying eigenfunctions. We construct a renormalized Evans function and study bifurcations of embedded eigenvalues, when an algebraically decaying potential is perturbed by a generic potential with a faster decay at infinity. We show that the bifurcation problem for embedded eigenvalues can be reduced to cubic or quadratic equations, depending on whether the algebraic potential decays to zero or approaches a nonzero constant. Roots of the bifurcation equations define eigenvalues which correspond to nonlinear waves that are formed from unstable algebraic solitons. Our results provide precise information on the transformation of unstable algebraic solitons in the time-evolution problem associated with the integrable nonlinear equation. Algebraic solitons of the modified KdV equation are shown to transform to either travelling solitons or time-periodic breathers, depending on the sign of the perturbation. Algebraic solitons of the derivative NLS and massive Thirring equations are shown to transform to travelling and rotating solitons for either sign of the perturbation. Finally, algebraic homoclinic orbits of the focusing NLS equation are destroyed by the perturbation and evolve into time-periodic space-decaying solutions.
The QT Interval and Drug-Associated Torsades de Pointes

Torsades de pointes is an uncommon form of ventricular tachyarrhythmia, which may occur in the presence or absence of drug therapy. There are several difficulties in establishing a relationship between drug therapy and the induction of this arrhythmia. Drugs for which a definitive association with torsades de pointes are established, i.e. class IA and III antiarrhythmics, are known to prolong the QT or QTC interval. However, the definition of significant QT or QTC prolongation is sometimes difficult because there is a significant inter- and intrapatient variability in the observed QT or QTC interval even in the absence of drug therapy. Furthermore, some drugs that induce prolongation of the QT or QTC interval in a given patient do not precipitate torsades de pointes. Recent reports of unexpected drug-induced torsades de pointes by drugs other than class IA or III antiarrhythmics led to the examination of the association between QT interval prolongation and torsades de pointes, and evaluation of the mechanisms for drug-induced torsades de pointes by drugs other than class IA or III antiarrhythmic drugs.
Connected Components in MapReduce and Beyond

Computing connected components of a graph lies at the core of many data mining algorithms, and is a fundamental subroutine in graph clustering. This problem is well studied, yet many of the algorithms with good theoretical guarantees perform poorly in practice, especially when faced with graphs with hundreds of billions of edges. In this paper, we design improved algorithms based on traditional MapReduce architecture for large scale data analysis. We also explore the effect of augmenting MapReduce with a distributed hash table (DHT) service. We show that these algorithms have provable theoretical guarantees, and easily outperform previously studied algorithms, sometimes by more than an order of magnitude. In particular, our iterative MapReduce algorithms run 3 to 15 times faster than the best previously studied algorithms, and the MapReduce implementation using a DHT is 10 to 30 times faster than the best previously studied algorithms. These are the fastest algorithms that easily scale to graphs with hundreds of billions of edges.
Ring current simulations of the 90 intense storms during solar cycle 23

[1] All of the intense magnetic storms (minimum Dst value of <−100 nT) from solar cycle 23 (1996–2005) were simulated using the hot electron and ion drift integrator (HEIDI) model. The simulations were run using a Kp-driven shielded Volland-Stern electric field, static dipole magnetic field, and nightside plasma data from instruments on the Los Alamos geosynchronous satellites. Of the 90 events, 79 had acceptable plasma boundary condition coverage (with main phase data gaps of 4 h or less) and are included in the analysis. Storms were classified according to their solar wind driver, and means and correlations were examined. It is found that for this model configuration, the HEIDI model was able to best reproduce the Dst time series for sheath-driven events with an average minimum Dst* from the simulations at or below the observed minimum Dst* value. CIR-driven events were the least reproducible class of storms, with simulated minimum Dst* values typically only half to two thirds of the observed minimum value. In general, there was a strong correlation between the observed and modeled minimums of Dst* and essentially no correlation between the observed minimum Dst* and the modeled-to-observed Dst* ratio. This implies that the size of the eventual storm is not a good indicator of whether this version of HEIDI will be able to accurately reproduce it; rather, a Kp-driven HEIDI simulation is consistently on the low side of predicting storm intensity, except for sheath-driven events.
A Study of Mortality and Morbidity Among Persons Occupationally Exposed to ⩽50 mSv in a Year: Phase I, Mortality Through 1984

Abstract A retrospective follow-up study is in progress of mortality and morbidity among persons who reportedly received greater than or equal to 5 rem [50 millisieverts (mSv)] of penetrating ionizing radiation in any calendar year of employment at all facilities operated for the U.S. Department of Energy (DOE) or its predecessor agencies. The purpose is to identify any adverse health outcomes and to determine if any such outcomes are related to prior occupational radiation exposure at these facilities. A population of 3145 present and former civilian employees at DOE facilities and at the U.S. Navy's Nuclear Reactor Propulsion Program (NRPP) who meet the radiation exposure criteria were identified from personnel radiation monitoring records maintained at the facilities for the years 1943 through 1978. Vital status through 1984 was determined for 86.6 percent of this population; 588 deaths (18.6%) were observed. The median career external radiation dose for individuals in the population through 1978 was 1...
The fluid stochastic Petri net simulator

A Fluid Stochastic Petri Net (FSPN) extends a normal Petri net with the notion of fluid places, and fluid arcs. Fluid levels are continuous, and may be used to approximate the presence of many discrete tokens. We describe an FSPN simulation tool whose input description extends the syntax of the widely used tool spnp.
Cultural Teaching: The Development of Teaching Skills in Maya Sibling Interactions

Psychology has considered the development of learning, but the development of teaching in childhood has not been considered. The data presented in this article demonstrate that children develop teaching skills over the course of middle childhood. Seventy-two Maya children (25 boys, 47 girls) ranging in age from 3 to 11 years (M = 6.8 years) were videotaped in sibling caretaking interactions with their 2-year-old brothers and sisters (18 boys, 18 girls). In the context of play, older siblings taught their younger siblings how to do everyday tasks such as washing and cooking. Ethnographic observations, discourse analyses, and quantification of discourse findings showed that children's teaching skills increased over the course of middle childhood. By the age of 4 years, children took responsibility for initiating teaching situations with their toddler siblings. By the age of 8 years, children were highly skilled in using talk combined with manual demonstrations, verbal feedback, explanations, and guiding the body of younger learners. Children's developing competence in teaching helped their younger siblings increase their participation in culturally important tasks.
Effects of Predation Risk on Vertical Habitat Use and Foraging of Pardosa milvina

Animals face the risk of predation while engaging in regular activities, such as foraging, mate-seeking, and reproducing. In order to avoid predation, prey can modify behavior to prevent capture. Pardosa milvina may climb in response to chemotactile cues of Hogna helluo, a larger cooccurring wolf spider, to avoid predation. The purpose of this study was to test the effects of the location of predator cues on the climbing response of P. milvina and to test how this antipredator behavior affected foraging success. In experimental arenas, when cues were on the bottom of the containers, P. milvina moved upward, and when cues were on the walls, individuals moved downward. These results suggest that P. milvina respond to H. helluo cues with general avoidance and do not automatically climb in response to the cues. As H. helluo spend most of their time on the ground, P. milvina may avoid predation by spending more time climbing in areas with H. helluo cues. The presence of predator cues significantly decreased foraging by P. milvina. But within the predator cue treatments, climbing ability had no effect on foraging, possibly due to the short height of the feeding arenas. Future studies are needed to determine if climbing by P. milvina in response to cues of H. helluo has direct and indirect negative effects on herbivores in the field.
Navigating the socio-bio-geo-chemistry and engineering of nitrogen management in two illinois tile-drained watersheds.

Reducing nitrate loads from corn and soybean, tile-drained, agricultural production systems in the Upper Mississippi River basin is a major challenge that has not been met. We evaluated a range of possible management practices from biophysical and social science perspectives that could reduce nitrate losses from tile-drained fields in the Upper Salt Fork and Embarras River watersheds of east-central Illinois. Long-term water quality monitoring on these watersheds showed that nitrate losses averaged 30.6 and 23.0 kg nitrate N ha -1 yr -1 (Embarras and Upper Salt Fork watersheds, respectively), with maximum nitrate concentrations between 14 and 18 mg N L -1 . With a series of on-farm studies, we conducted tile monitoring to evaluate several possible nitrate reduction conservation practices. Fertilizer timing and cover crops reduced nitrate losses (30% reduction in a year with large nitrate losses), whereas drainage water management on one tile system demonstrated the problems with possible retrofit designs (water flowed laterally from the drainage water management tile to the free drainage system nearby). Tile woodchip bioreactors had good nitrate removal in 2012 (80% nitrate reduction), and wetlands had previously been shown to remove nitrate (45% reductions) in the Embarras watershed. Interviews and surveys indicated strong environmental concern and stewardship ethics among landowners and farmers, but the many financial and operational constraints that they operate under limited their willingness to adopt conservation practices that targeted nitrate reduction. Under the policy and production systems currently in place, large-scale reductions in nitrate losses from watersheds such as these in east-central Illinois will be difficult.
Plane wave scattering from three dimensional multiple objects using the iterative multiregion technique based on the FDFD method

An iterative approach using the finite difference frequency domain method is presented in this paper in order to solve the problem of scattering from large three-dimensional electromagnetic scatterers. The idea of iterative multiregion technique is introduced to divide one computational domain into smaller subregions and solve each subregion separately. Then the subregion solutions are combined iteratively to obtain a solution for the complete domain. As a result, a considerable reduction in the computation time and memory has been achieved.
Altered acquisition and extinction of amphetamine-paired context conditioning in genetic mouse models of altered NMDA receptor function.

Repeated intermittent exposure to amphetamine (AMPH) results in the development of persistent behavioral and neurological changes. When drug exposure is paired with a specific environment, contextual cues can control conditioned responses, context-specific sensitization, and alterations in dendritic morphology in the nucleus accumbens (NAc). Intact N-methyl-D-aspartate (NMDA) glutamate receptor signaling is thought to be required for associative learning. The acquisition of context-specific behavioral sensitization to AMPH and extinction of conditioned hyperactivity have been investigated in two genetically modified mouse strains: the serine racemase homozygous knockout (SR−/−) and glycine transporter 1 heterozygous mutant (GlyT1−/+). These strains have reciprocally altered NMDA receptor co-agonists, D-serine and glycine, levels that result in decreased (SR−/−) or increased (GlyT1−/+) NMDA receptor signaling. AMPH-induced changes in dendritic morphology in the NAc were also examined. SR−/− mice showed reduced expression of context-specific sensitization and conditioned hyperactivity. However, the conditioned hyperactivity in these mice is completely resistant to extinction. Extinction reversed AMPH-induced increased in NAc spine density in wild-type but not SR−/− mice. GlyT1 −/+ mice showed a more rapid acquisition of sensitization, but no alteration in the extinction of conditioned hyperactivity. The SR−/− data demonstrate that a genetic model of NMDA receptor hypofunction displays a reduced ability to extinguish conditioned responses to drug-associated stimuli. Findings also demonstrate that the morphological changes in the NAc encode conditioned responses that are sensitive to extinction and reduced NMDA receptor activity. NMDA receptor hypofunction may contribute to the comorbidity of substance abuse in schizophrenia.
Effects of three-dimensional culturing on osteosarcoma cells grown in a fibrous matrix: analyses of cell morphology, cell cycle, and apoptosis.

Osteosarcoma cells were cultured in stirred tank bioreactors with either a fibrous matrix or nonporous microcarriers to study the environmental effects on cell growth, morphology, cell cycle, and apoptosis. Cell cycle and apoptosis were analyzed using flow cytometry and visualized using confocal laser scanning microscopy and fluorescence microscopy. The three-dimensional (3-D) fibrous culture had better cell growth and higher metabolic rates than the two-dimensional (2-D) microcarrier culture because cells in the fibrous matrix were protected from shear stress and had lower apoptosis and cell death even under suboptimal conditions (e.g., nutrient depletion). The polyester fibrous matrix used in this study also exhibited the capability of selectively retaining viable and nonapoptotic cells and disposing apoptotic and nonviable cells. Consequently, very few apoptotic cells were found in the fibrous matrix even in the long-term (1 month) T-flask culture. In the continuous culture with packed fibrous matrixes for cell support, most cells were arrested in the G1/G0 phase after 4 days. Decreasing the dissolved oxygen level from 60 to 10% air saturation did not significantly change cell cycle and apoptosis, which remained low at ∼15%. These results could explain why the fibrous bed bioreactor had good long-term stability and was advantageous for production of non-growth-associated proteins by animal cell cultures.
Introducing porous silicon as a getter using the self aligned maskless process to enhance the quality factor of packaged MEMS resonators

Vacuum encapsulated MEMS resonators are used in frequency references and gyroscopes. We present the use of porous silicon as a getter material for MEMS devices. Two types of devices were fabricated using the electrochemical etching and compared for quality factor. One type was with a cavity in the substrate of an SOI die, which helps in reducing the parasitic capacitance and the air damping. The other was with cavity and porous silicon (getter) in the substrate. The measured resonant profiles show that the device with the getter material has 2× higher quality factor than the one without the getter.
Lack of effect of ovarian cycle and oral contraceptives on baroreceptor and nonbaroreceptor control of sympathetic nerve activity in healthy women.

Endogenous and exogenous female hormones regulate sympathetic nerve activity (SNA) in animal models, but their impact in humans is controversial. The purpose of this study is to investigate the eff...
Mediating effects of wrist reaction torque on grip force production

Abstract A pistol grip, power tool simulator was developed and used to examine the mediating effects of wrist reaction torque on changes in direct measures of grip force. The effects of thrust force (0 and 45 N), and pre-existing grip force (10 and 30% MVC) were also controlled with this simulator. A modified Jamar dynamometer attached to the motor shaft, permitted grip forces to be measured directly. A 2×2×2×2, repeated measures ANOVA, was used to test the effects of torque impulse magnitude, duration, thrust force, and pre-existing grip force on changes in normalized grip force. Subjects included 11 males and 8 females. Grip force increased significantly (31–254%) with increasing torque magnitude. Grip force decreased (15–37%) with increasing pre-torque grip force. Grip force was not significantly affected by torque duration. Grip force also decreased 10–31% with increasing thrust force. Derived measures of hand-wrist dynamic compliance decreased significantly with increases in torque duration, thrust force, torque magnitude, and pre-torque grip force. The wrist actively stiffened under these conditions. Relevance to industry Manufacturers of powered hand tools may find this study useful to further their understanding of the effects of tool use on the hand–wrist system. The importance of torque shut-off mechanisms and a continued attention to optimal handle design is also supported by this work.
Changing Patterns of Significant Authors on Leadership and Managerial Effectiveness

This paper develops four lists of leading authors on leadership and managerial effectiveness and examines the distribution over time of works by those authors on those topics. In this way, not only are leading authors identified, but changing patterns are also determined. This approach suggests that number of citations, while inadequate as a sole measure of importance, may assist in identifying leading authors for teachers to use in course design, scholars to use in literature searches, and students of management thought to use in examining patterns of change.
A long-term approach to improving human-robot interaction: RoboCupJunior Rescue

This paper describes the motivation behind and development of a USAR environment for the entry-level division of RoboCup, namely RoboCupJunior Rescue. We describe the challenge as it has evolved since 2000. Further, we explain how we see a place for this initiative as part of a long-term plan to address issues in human-robot interaction, advancing technical literacy by introducing young students to robotics within a socially significant context. The need to be able to interact with technology is growing increasingly important. Preparing the next generation by exposing today's students to hands-on technology early on provides a more sophisticated population that is ready and willing to interact with complex technology whenever and if ever they need to - no matter whether these students become engineers, roboticists, schoolteachers, fire-fighters, ambulance drivers, doctors or lawyers.
Considerations for estimating the 20th century trend in global mean sea level

Recent efforts in reconstructing historical sea level change have led to a range of published estimates for the global mean sea level trend over the last century. Disagreement in these estimates can be attributed to two factors: (1) differences in analysis and/or reconstruction techniques and (2) differences in tide gauge selection and quality control of the data. Here the impact of tide gauge selection is explored by calculating global mean trends using three different tide gauge data sets that have been utilized in recent reconstruction studies. The inclusion of tide gauge records that are affected by unresolved internal variability and/or unaccounted for vertical land motion are found to significantly impact the estimates of the long-term trend in global mean sea level. In conclusion, several guidelines are presented regarding the selection of tide gauges for use in historical reconstructions focused on estimating the 20th century global mean sea level trend.