cssi/SciSciGPT-SciSciNet huggingface dataset:
The effectiveness of microcomputer simulations in the principles of economics course

Abstract This paper reports a controlled experiment investigating the instructional effectiveness of a textbook-based microcomputer simulation program in the traditional Principles of Economics course. A group of economics students at Mississippi State University were required to work through a macroeconomic policy simulation program as part of their course of study. These students were pre- and post-tested using the Revised Test of Understanding College Economics and the Attitude Towards Economics dimension of the Survey of Economic Attitudes. Changes in their test scores are compared to those of students in a traditional lecture class not exposed to the simulation program. A MANOVA analysis of the data indicates a difference in economic learning and attitude formation between the class groups. The results suggest that students using the computer simulation significantly improved their ability to solve implicitly stated problems in economics and left the class with more positive attitudes toward the discipline than students who did not use the simulation. The authors conclude that computerized simulations can be an effective instructional device in the Principles of Economics course.
An operating system for a central real-time data-processing computer

A detailed study of the laboratory data-processing needs of our Chemistry Division has shown that about 25 unrelated experiments (see Table I) will require or greatly benefit from real-time computer service. An assessment of the nature of these requirements and a careful study of the capabilities of the Sigma 7 computer clearly indicate that this work load could be handled by such a central computer. This load will use up to 10% of the I/O capacity of the system and require about 40% of the Central Processor time to satisfy the real-time needs of all the experiments if they are running simultaneously. An additional 30% of the Central Processor capability would be used to perform final processing and analysis of the data at the end of each experiment. Further examination of the problem indicated that while a comparable amount of money would have to be spent whether we purchased individual computers for each experiment or a single Sigma 7 system, the service that could be provided by the central system would be far superior to the individual small computer service. In addition to the usual features found in third generation computers, the Sigma 7 has true independent Input/Output processors, independent memory modules and a high speed random access device (3 X 106 bytes/sec transfer rate), all of which are essential for the efficient operation of a large data-collection and processing system.
Sea surface temperature and the brown shrimp (Farfantepenaeus aztecus) population on the Alabama, Mississippi, Louisiana and Texas continental shelves

Abstract Analysis of the Southeast Area Monitoring and Assessment Program – Gulf of Mexico (SEAMAP-GM) summer and fall trawl survey data covering the Alabama, Mississippi, Louisiana and Texas continental shelves for the period 1987–2000 shows that the annual number n and weight w of the brown shrimp per trawl is positively correlated with annual sea surface temperature (SST) averaged over the continental shelves. Correlations of the monthly anomalous SST by calendar month with the annual shrimp data are highest in April and May. Past work has suggested a possible reason for this: juvenile brown shrimp, which mainly develop from postlarvae in coastal estuaries in April and May, grow faster in warmer water and are therefore more likely to escape predators. Since the juvenile shrimp population is a good predictor of the adult shelf shrimp population, and since the estuarine and shelf SST are closely linked, it is reasonable that April and May shelf SST should be positively correlated with the number and weight of brown shrimp per trawl. Shrimp are more numerous in the summer and the correlation of April and May SST anomaly is much higher for the number and weight per trawl in the summer than in the fall. Hindcasts are made using the simple linear statistical prediction model n = α + β · SSTA , where SSTA is the anomalous April–May departure of SST from the annual cycle. The cross-verified correlation between model and observed n is r = 0.77. A similar model for w gave r = 0.79. A prediction model for summer shrimp alone had cross-verified correlations r = 0.79 for n and 0.86 for w. Based on the 2004 April–May SST anomaly, annual and summer models predict that n and w should be close to average in 2004.
Synthesis of (S)-mappicine and mappicine ketone via radical cascade reaction of isonitriles

Abstract ( S )-Mappicine ( 2 ) and mappicine ketone ( 1 ) have been prepared from methylacetoacetate ( 4 ) by a strategy featuring a radical cascade reaction of an isonitrile as the key step. The introduction of the hydroxy group of ( S )-mappicine occurred with moderate selectivity through asymmetric hydroxylation.
C∗-algebras and Fell bundles associated to a textile system

Abstract The notion of textile system was introduced by M. Nasu in order to analyze endomorphisms and automorphisms of topological Markov shifts. A textile system is given by two finite directed graphs G and H and two morphisms p , q : G → H , with some extra properties. It turns out that a textile system determines a first quadrant two-dimensional shift of finite type, via a collection of Wang tiles, and conversely, any such shift is conjugate to a textile shift. In the case the morphisms p and q have the path lifting property, we prove that they induce groupoid morphisms π , ρ : Γ ( G ) → Γ ( H ) between the corresponding etale groupoids of G and H . We define two families A ( m , n ) and A ¯ ( m , n ) of C ∗ -algebras associated to a textile shift, and compute them in specific cases. These are graph algebras, associated to some one-dimensional shifts of finite type constructed from the textile shift. Under extra hypotheses, we also define two families of Fell bundles which encode the complexity of these two-dimensional shifts. We consider several classes of examples of textile shifts, including the full shift, the Golden Mean shift and shifts associated to rank two graphs.
Nonlinear Dynamic Combustion in Solid Rockets: L* Effects

nonlinear combustion phenomena that have been observed experimentally but that are beyond the capability of linearized models are also predicted. These include rapid initial (over-) pressurization, propellant extinction, and dual-frequency and limit-cycle oscillations. The results suggest that some of these combustion phenomena could be due to nonlinear (but still quasi ‐steady) dynamic burning and mass conservation effects within the classical bulk-mode framework rather than more complicated e uid and e ame dynamic effects that have been proposed. In particular, the rapid rate of initial pressurization and the ignition spike commonly attributed to erosive burning may be due to nonlinear dynamic burning at low L ¤ . Even without an overpressurization spike, it appears that
Catalytic amide formation with α'-hydroxyenones as acylating reagents

α′-Hydroxyenones undergo clean, catalytic amidations with amines promoted by the combination of an N-heterocyclic carbene and 1,2,4-triazole.
Inflation and the comprehensive tax base

Abstract Adjusting the basis of assets for inflation is discussed and compared with partial inclusion of gains. The importance of deferral is discussed and compared with the importance of adjustment for inflation.
Seasonal cycle of nonmigrating diurnal tides in the MLT region due to tropospheric heating rates from the NCEP/NCAR Reanalysis Project

Abstract The Global Scale Wave Model (GSWM), combined with a climatological model of zonal mean winds and tropospheric heating rates from the NCEP/NCAR Reanalysis Project, is used to investigate three nonmigrating tidal oscillations of importance to the MLT region: the eastward-propagating diurnal tide with zonal wavenumber s = −3 (DE3), the standing ( s = 0) diurnal oscillation (D0), and the westward-propagating tide with s = 2 (DW2). Monthly climatological winds associated with these oscillations are compared with observations, and the relative importance of mean winds, dissipation and source distributions in determining seasonal-latitudinal structures are explored. Major inconsistencies are revealed, motivating the need for models that realistically address troposphere heating and nonlinear tide-planetary wave interactions as tidal sources.
Computation and Simulation of Wake-Generated Unsteady Pressure and Boundary Layers in Cascades: Part 1—Description of the Approach and Validation

The unsteady pressure and boundary layers on a turbomachinery blade row arising from periodic wakes due to upstream blade rows are investigated in this paper. A time-accurate Euler solver has been developed using an explicit four-stage Runge-Kutta scheme. Two-dimensional unsteady nonreflecting boundary conditions are used at the inlet and the outlet of the computational domain. The unsteady Euler solver captures the wake propagation and the resulting unsteady pressure field, which is then used as the input for a two-dimensional unsteady boundary layer procedure to predict the unsteady response of blade boundary layers. The boundary layer code includes an advanced {kappa}-{epsilon} model developed for unsteady turbulent boundary layers. The present computational procedure has been validated against analytic solutions and experimental measurements. The validation cases include unsteady inviscid flows in a flat-plate cascade and a compressor exit guide vane (EGV) cascade, unsteady turbulent boundary layer on a flat plate subject to a traveling wave, unsteady transitional boundary layer due to wake passing, and unsteady flow at the midspan section of an axial compressor stator. The present numerical procedure is both efficient and accurate in predicting the unsteady flow physics resulting from wake/blade-row interaction, including wake-induced unsteady transition of blade boundary layers.
A top-down approach to teaching introductory computer graphics

Abstract There are two common strategies for teaching introductory computer graphics (CG) programming. The first and most traditional covers the CG field in a bottom-up manner starting from fundamental algorithms such as triangle rasterization. The second proceeds in a top-down manner by analyzing the functional modules of applications. This paper argues that the top-down approach is well-suited for mature adult students. A course that has successfully implemented a top-down approach is then described.
Millimeter Flares and VLBI Visibilities from Relativistic Simulations of Magnetized Accretion Onto the Galactic Center Black Hole

The recent very long baseline interferometry (VLBI) observation of the Galactic center black hole candidate Sgr A* at 1.3 mm shows source structure on event-horizon scales. This detection enables a direct comparison of the emission region with models of the accretion flow onto the black hole. We present the first results from time-dependent radiative transfer of general relativistic MHD simulation data, and compare simulated synchrotron images at black hole spin a = 0.9 with the VLBI measurements. After tuning the accretion rate to match the millimeter flux, we find excellent agreement between predicted and observed visibilities, even when viewed face-on (i 30?). VLBI measurements on 2000-3000 km baselines should constrain the inclination. The data constrain the accretion rate to be (1.0-2.3)?10?9 M ? yr?1 with 99% confidence, consistent with but independent of prior estimates derived from spectroscopic and polarimetric measurements. Finally, we compute light curves, which show that magnetic turbulence can directly produce flaring events with 0.5 hr rise times, 2-3.5?hr durations, and 40%-50% flux modulation, in agreement with observations of Sgr A* at millimeter wavelengths.
Carbon nanotube electronics

Abstract We first discuss the one-dimensional (1D) electronic structure of carbon nanotubes (CNTs) and its influence on the carrier scattering mechanisms in metallic CNTs. We then focus our attention on semiconducting CNTs and CNT-based electronic devices. We start by discussing the structure and function of p-type field-effect transistors (CNTFETs). Then the preparation and properties of ambipolar CNTFETs is described. We show that in addition to doping with donor atoms, n-type transistors can be generated by simply annealing the p-CNTFETs in vacuum. The latter process is reversible upon oxygen exposure. We propose that the commonly found p-character of the as-prepared CNTs is neither an intrinsic nanotube property nor does it reflect their doping, but is determined by the nature of carrier injection at the contacts. The ability to generate both p- and n-CNTFETs allows us to build complementary logic circuits. We present results on two voltage inverters (“NOT gates”), an intermolecular one and an intramolecular one. In the latter, the logic function is encoded along the length of a single CNT or CNT bundle. Finally, we focus on the electronic properties and device fabrication in composite CNT systems, i.e., multi-walled (MW) and single-walled (SW) CNT bundles. We discuss the current-induced breakdown process in these materials and use it to: (a) take apart shell-by-shell MWCNTs and electrically characterize each shell, (b) develop the process of “constructive destruction” which allows the fabrication of arrays of CNTFETs out of bundles of SWCNTs without the need to first separate metallic from semiconducting nanotubes.
Yaw rate estimation for vehicle control applications

This paper describes a method for vehicle yaw rate estimation using two accelerometers and a steer angle sensor. This yaw rate estimate can be used as an inexpensive alternative to commercial yaw rate sensors in vehicle control applications. The pro­ posed method combines two complementary approaches to yaw rate estimation using accelerometers. This new method is superior to either method used by itself. This paper presents the new approach, supporting analyses, simulation results and experi­ mental validation. The simulation results are based upon both linear and nonlinear vehicle dynamics models and include important effects such as sensor drift and noise, disturbances acting on the vehicle, and model uncertainties. The experimental validation is based on test data from a specially instrumented vehicle driven on a test track. These results indicate that the proposed yaw rate estimation scheme per­ forms well for a wide range of operating conditions and is not difficult to implement. In recent years, there has been a tremendous increase in inter­ est in advanced safety features in an automobile. This has led to the development of advanced vehicle chassis control systems such as anti-lock brakes (ABS), traction control, four wheel steer, electronic stability program, etc. Yaw rate is an important element of the vehicle dynamics that influences the driver's (and passenger's) perception of vehicle handling and safety features. Hence, a considerable level of effort is being directed towards developing reliable and accurate methods to monitor and control the yaw rate of an automobile. This paper describes a reliable and inexpensive new approach for estimating the yaw rate of a vehicle using accelerometers. Consider the schematic of a vehicle shown in Fig. 1. The vehicle heading angle, i/-'(f)> is defined as the angle between the inertial X-axis (of the inertial X-Y-Z coordinate frame) and the body fixed A;-axis (of the vehicle-fixed x-y-z coordinate frame). The time rate of change of i/'(0. with respect to the vehicle-fixed coordinate system x-y-z, is the yaw rate, r{t). It is necessary to measure the vehicle yaw rate in various vehicle control appli­ cations, such as brake-steer (Pilutti et al, 1998), lateral dynam­ ics control and safety warning systems such as collision warning and roadway departure warning systems. In order to measure the yaw rate, sensors are commercially available for use in vehicle control research. Currently, these sensors cost several hundred dollars each even in mass production quantities. This cost is extremely prohibitive for use in mass produced automo­ biles. Although it is expected that the cost of such sensors will be dramatically reduced in the future, it is of interest to consider methods to estimate the yaw rate accurately for near term use in vehicles. Besides being used to generate an approximate yaw rate measurement for vehicle control applications in the near term, these estimators can be used in the future as redundant (i.e., "backup") sensors for diagnostic purposes in a vehicle with a yaw rate sensor.
Contemporary trends in postchemotherapy retroperitoneal lymph node dissection: Additional procedures and perioperative complications.

Abstract Introduction Postchemotherapy retroperitoneal lymph node dissection (PC-RPLND) is a mainstay in the treatment of men with metastatic testicular cancer. We sought to determine whether trends in the need for additional intraoperative procedures and development of perioperative complications have changed over time. Methods Patients undergoing PC-RPLND from 2003 to 2011 were identified in the Indiana University Testis Cancer Database. Trends in the incidence of perioperative complications and additional procedures were assessed over time using regression tests of trend. Complications were classified according to the modified Clavien system. Univariable and multivariable logistic regression was used to determine factors associated with undergoing additional procedures. Results After exclusion criteria, 755 patients were included in the final study cohort. The incidence of additional procedures at PC-RPLND was 22.1% (167 of 755). The rate of additional procedures per year ranged from 17% to 30%, with no significant trend in any direction ( P trend = 0.66). After adjusting for covariates, preoperative retroperitoneal (RP) mass size, elevated markers, and RP pathology remained significantly associated with the odds of an additional procedure. RP mass size of>10 cm was the strongest predictor (odds ratio = 7.2, 95% CI: 2.6–19.5). Overall, the incidence of perioperative complications was 3.7% (28 of 755). The rate of perioperative complications per year ranged from 0% to 7.3% with no significant trend in any direction ( P trend = 0.06). Conclusion The incidence of perioperative complications is low with no significant trend over the last decade. A substantial number of patients require additional intraoperative procedures during PC-RPLND, which has remained stable at our institution over time.
Fostering subnational autonomy and accountability in decentralized developing countries: lessons from the Papua New Guinea experience

Using the experience of Papua New Guinea as a case study, this article examines the importance of political and administrative organization, electoral politics and revenue assignments for fostering subnational autonomy and accountability in decentralized developing countries, and hence the success of fiscal decentralization programmes. Copyright © 2002 John Wiley & Sons, Ltd.
An experimental investigation of convection in a fluid that exhibits phase change

Convection flows have been systematically observed in a layer of fluid between two isothermal horizontal boundaries. The working fluid was a nematic liquid crystal, which exhibits a liquid–liquid phase change at which latent heat is released and the density changed. In addition to ordinary Rayleigh–Benard convection when either phase is present alone, there exist two distinct types of convective motions initiated by the unstable density difference. When a thin layer of heavy fluid is present near the top boundary, hexagons with downgoing centres exist with no imposed thermal gradient. When a thin layer of light fluid is brought on near the lower boundary, the hexagons have upshooting centres. In both cases, the motions are kept going once they are initiated by the instability due to release of latent heat. Relation of the results to applicable theories is discussed.
Will Solar-Driven Water-Splitting Devices See the Light of Day?

Through decades of sustained effort, researchers have made substantial progress on developing technologies for solar-driven water splitting. Nevertheless, more basic research is needed before prototype devices with a chance for commercial success can be demonstrated. In this Perspective, we summarize the major design constraints that motivate continued research in the field of solar-driven water splitting. Additionally, we discuss key device components that are now available for use in demonstration systems and prototypes. Finally, we highlight research areas where breakthroughs will be critical for continued progress toward commercial viability for solar-driven water-splitting devices.
State takeover legislation and share values: The wealth effects of Pennsylvania's Act 36

Abstract Proponents of state antitakeover legislation argue that previous empirical tests by financial economists of the wealth effects of Pennsylvania's 1990 antitakeover law are biased. We show that the proponents are correct. In particular, firm size, event-time clustering, and non-synchronous trading effects account for the wealth decreases reported in earlier studies. We also show, however, that both proponents and critics of the Pennsylvania legislation have ignored the earliest press release about it. The wealth effect associated with this announcement is negative, large, and statistically significant. These results therefore are consistent with the hypothesis that the Pennsylvania law decreased company values and with the hypothesis that the initial market reaction is an unbiased estimate of the law's effect on firm values.
Stereocontrolled Synthesis of α-Amino-α′-alkoxy Ketones by a Copper-Catalyzed Cross-Coupling of Peptidic Thiol Esters and α-Alkoxyalkylstannanes

A stereocontrolled synthesis of α-amino-α′-alkoxy ketones is described. This pH-neutral copper(I) thiophene-2-carboxylate (CuTC)-catalyzed cross-coupling of amino acid thiol esters and chiral nonracemic α-alkoxyalkylstannanes gives α-amino-α′-alkoxy ketones in good to excellent yields with complete retention of configuration at the α-amino- and α-alkoxy-substituted stereocenters.
Structure and mechanism of maximum stability of isolated alpha-helical protein domains at a critical length scale

The stability of alpha helices is important in protein folding, bioinspired materials design, and controls many biological properties under physiological and disease conditions. Here we show that a naturally favored alpha helix length of 9 to 17 amino acids exists at which the propensity towards the formation of this secondary structure is maximized. We use a combination of thermodynamical analysis, well-tempered metadynamics molecular simulation and statistical analyses of experimental alpha helix length distributions and find that the favored alpha helix length is caused by a competition between alpha helix folding, unfolding into a random coil and formation of higher-order tertiary structures. The theoretical result is suggested to be used to explain the statistical distribution of the length of alpha helices observed in natural protein structures. Our study provides mechanistic insight into fundamental controlling parameters in alpha helix structure formation and potentially other biopolymers or synthetic materials. The result advances our fundamental understanding of size effects in the stability of protein structures and may enable the design of de novo alpha-helical protein materials.
A Comparative Study between Shielded and Open Coplanar Waveguide Discontinuities

Received January 17, 1992; revised April 14, 1992.ABSTRACTA comparative study between open and shielded coplanar wavegnide (CPW) discontinuitiesis presented. In this study, the space domain integral equation method is used to characterizeseveral discontinuities such as the open-end CPW and CPW series stubs. Two differentgeometries of CPW series stubs (straight and bent stubs) are compared with respect toresonant frequeney and radiation loss. In addition, the encountered radiation loss due todifferent CPW shunt stubs is evaluated experimentally. The notion of forced radiationsimulation is presented, and the results of such a simulation are compared to the actualradiation loss obtained rigorously. It is shown that such a simulation cannot give reliableresults concerning radiation loss from printed circuits. © 1992 John Wiley & Sons, inc.
Design and performance of MPEG video streaming to palmtop computers

Today's wide variety of computing devices offer a large range of resource availability. These resources include CPU speed, bandwidth, and memory. Workstations and PCs typically are rich in resources, whereas palmtop devices are generally quite limited. This disparity offers challenges to integrating these heterogeneous devices into a single distributed system. Services must be available to each device, but it may be necessary to modify certain services if the connected device does not have the required resources to support them. Proxies may be introduced into the system to off-load computations that would preclude certain services to resource-deprived devices. We have implemented one such proxy that enables the viewing of live MPEG video on the 3Com PalmPilot. The proxy is able to transform the video feed on-the-fly, removing extraneous information, thereby reducing CPU and memory requirements and allowing palm devices to participate in video sessions. This paper discusses the design and performance of our video proxy targeted for 3Com PalmPilot handheld computers. Several protocols are compared and the advantages of each are discussed.
Novel Hybrid Market Price Forecasting Method With Data Clustering Techniques for EV Charging Station Application

In addition to providing charging service, an electric vehicle charging station equipped with a distributed energy storage system can also participate in the deregulated market to optimize the cost of operation. To support this function, it is necessary to achieve sufficient accuracy on the forecasting of energy resources and market prices. The deregulated market price prediction presents challenges since the occurrence and magnitude of the price spikes are difficult to estimate. This paper proposes a hybrid method for very short term market price forecasting to improve prediction accuracy on both nonspike and spike wholesale market prices. First, support vector classification is carried out to predict spike price occurrence, and support vector regression is used to forecast the magnitude for both nonspike and spike market prices. Additionally, three clustering techniques including classification and regression trees, K-means, and stratification methods are introduced to mitigate high error spike magnitude estimation. The performance of the proposed hybrid method is validated with the Electric Reliability Commission of Texas wholesale market price. The results from the proposed method show a significant improvement over typical approaches.
The continuum limit of sl( N/ K) integrable super spin chains

Abstract I discuss in this paper the continuum limit of integrable spin chains based on the superalgebras sl(N/K) . The general conclusion is that, with the full “supersymmetry”, none of these models is relativistic. When the supersymmetry is broken by the generator of the sub u(1) , Gross–Neveu models of various types are obtained. For instance, in the case of sl(N/K) with a typical fermionic representation on every site, the continuum limit is the GN model with N colors and K flavors. In the case of sl(N/1) and atypical representations of spin j , a close cousin of the GN model with N colors and j flavors with flavor anisotropy is obtained. The Dynkin parameter associated with the fermionic root, while providing solutions of the Yang–Baxter equation with a continuous parameter, thus does not give rise to any new physics in the field theory limit. These features generalize to the case where an impurity is embedded in the system.
Probabilistic inductive inference: a survey

This paper surveys developments in probabilistic inductive inference (learning) of recursive (computable) functions. We mainly focus on finite learning, since this simple paradigm has produced the most interesting (and most complex) results.
Supergravity Solutions for Localised Brane Intersections

We present a general method for constructing supergravity solutions for intersecting branes. The solutions are written in terms of a single function, which is the solution to a nonlinear differential equation. We illustrate this procedure in detail for the case of M2-branes ending on M5-branes. We also present supergravity solutions for strings ending on Dp-branes. Unlike previous results in the literature, these branes are completely localized.
Parallel Progressive Radiosity with Adaptive Meshing

Progressive radiosity is widely used for realistic image synthesis in computer graphics applications. High-quality image generation usually requires radiosity with adaptive patch refinement to account for global illumination effects from irregular objects whose proximity varies in a 3D space. Parallelizing such an algorithm is difficult since computation cost for each object varies from one iteration to another depending on the location of dynamically selected shooting patches. Dynamic load balancing is required but its overhead is high for distributed memory systems. This paper presents an efficient parallel algorithm for progressive radiosity, which adopts a static processor assignment strategy to take advantages of a hierarchical computation structure in this problem, minimize communication and balance dynamic load. Our experiments on a Meiko CS-2 distributed memory machine show that this algorithm has achieved good speedups for the tested cases.
Relativistic pseudopotentional incorporating core/valence polarization and nonlocal effects.

A relativistic pseudopotentional (RPP) for use in ab initio molecular electronic structure calculations is derived in the context of the relativistic effective core potential (REP) method of Lee et al. The resulting atom-specific RPP has salient features of the REP imbedded within it while retaining the form of a functional that is dynamically defined at runtime when used in calculations on molecules. The RPP is determined from Dirac−Fock wave functions for the isolated atom. Outer core two-electron interactions are incorporated into the RPP by means of variable coefficients that are defined in the context of the final molecular wave function. This form permits polarization of the outer core shells analogous to that occurring in all-electron molecular Hartree−Fock calculations while retaining these shells as part of the atomic pseudopotentional. Use of the RPP in post-Hartree−Fock molecular calculations permits the incorporation of core/valence correlation effects.
Sociological analysis of public attitudes toward computers and information files

As individuals increasingly experience a variety of contacts with computers, it becomes important to know something about the impact of these contacts and how different sectors of society feel about computerization. Such knowledge would (not only) give us insight into the source of public attitudes toward computers but would provide some basis upon which to anticipate public acceptance or rejection of computerization. These considerations should be taken into account in planning future computer applications, particularly social information systems.
A Theoretical Technique for Analyzing Aeroelastic Stability of Bearingless Rotors

A technique is introduced for aeroelastic stability analysis of certain hingeless helicopter rotors termed bearingless because of their lack of a pitch-change bearing. The rotor is modeled as three or more rigid blades, each joined to the hub by means of a flexible appendage known as the flexbeam or strap. The pitch-control system twists the flexbeam to provide blade pitch change. The analysis is capable of treating effects of several different pitch-control configurations, geometic nonlinearities associated with the equilibrium deflected shape of the flexbeam, and the built-in angular offsets of the flexbeam and blade. Numerical results are presented for a variety of system parameters. The stability of the system in both hub-fixed motion and coupled rotor-body motion is considered. System parameters can be chosen to stabilize most soft in-plane configurations for the hub-fixed case. The same parameters will also, under certain conditions, stabilize the coupled rotor-body system in hovering flight (air resonance). When the rotorcraft is in ground contact, however, at zero thrust, it appears that these parameters are not as effective in stabilizing the system (ground resonance).
Depression partially mediates the relationship between alexithymia and somatization in a sample of healthy children

A link between alexithymia and somatization has been widely established, yet little is known about different factors that may influence this relationship. Evidence supporting the idea of psychopathology as a mediator has been presented but not widely tested, particularly in children. The present study examined depressive symptoms as a mediator of alexithymia and somatization in a sample of healthy children in order to better understand the alexithymia-somatization link from a developmental perspective. Results indicated that depression significantly partially mediated this relationship, at least for two facets of alexithymia (difficulty identifying and describing feelings). Possible mechanisms, implications, and directions for future research are discussed.
Deep MMT* Transit Survey of the Open Cluster M37. II. Variable Stars

We have conducted a deep (15 r 23), 20 night survey for transiting planets in the intermediate-age (~550 Myr) open cluster M37 (NGC 2099) using the Megacam wide-field mosaic CCD camera on the 6.5 m MMT. In this paper we present a catalog and light curves for 1445 variable stars; 1430 (99%) of these are new discoveries. We have discovered 20 new eclipsing binaries and 31 new short-period (P < 1 day ) pulsating stars. The bulk of the variables are most likely rapidly rotating young low-mass stars, including a substantial number (500) that are members of the cluster. We identify and analyze five particularly interesting individual variables, including a previously identified variable that we suggest is probably a hybrid γ Doradus/δ Scuti pulsator, two possible quiescent cataclysmic variables, a detached eclipsing binary (DEB) with at least one γ Doradus pulsating component (only the second such variable found in an eclipsing binary), and a low-mass (MP ~ MS ~ 0.6 M☉) DEB that is a possible cluster member. A preliminary determination of the physical parameters for the DEB+γ Doradus system yields MP = 1.58 ± 0.04 M☉, MS = 1.58 ± 0.04 M☉, RP = 1.39 ± 0.07 R☉, and RS = 1.38 ± 0.07 R☉.
Time-reversal symmetry breaking and spontaneous anomalous Hall effect in Fermi fluids

We study the spontaneous nonmagnetic time-reversal symmetry breaking in a two-dimensional Fermi liquid without breaking either the translation symmetry or the U(1) charge symmetry. Assuming the low-energy physics is described by fermionic quasiparticle excitations, we identified an ``emergent'' local $\text{U}{(1)}^{N}$ symmetry in momentum space for an $N$-band model. For a large class of models, including all one-band and two-band models, we found that the time-reversal and chiral symmetry breaking can be described by the $\text{U}{(1)}^{N}$ gauge theory associated with this emergent local $\text{U}{(1)}^{N}$ symmetry. This conclusion enables the classification of the time-reversal symmetry-breaking states as types I and II, depending on the type of accompanying spatial symmetry breaking. The properties of each class are studied. In particular, we show that the states breaking both time reversal and chiral symmetries are described by spontaneously generated Berry phases. We also show examples of the time-reversal symmetry-breaking phases in several different microscopically motivated models and calculate their associated Hall conductance within a mean-field approximation. The fermionic nematic phase with time-reversal symmetry breaking is also presented and the possible realizations in strongly correlated models such as the Emery model are discussed.
Synthesizing Robust Communication Networks for Unmanned Aerial Vehicles With Resource Constraints

In this article, we address the problem of synthesizing communication networks for unmanned aerial vehicles (UAVs) in the presence of resource constraints. UAVs can be deployed as backbone nodes in ad hoc networks that can be central to civilian and military applications. The cost of operation of the network depends on the resources that are used such as the total power consumption associated with the network and the number of communication links in the network. The objective of the problem is to synthesize a communication network that maximizes connectivity subject to the cost of operation being within the specified budget for the resources. It is known that algebraic connectivity is a measure of robust connectivity and hence, it is chosen as an objective for optimization. We pose the network synthesis problem as a mixed-integer semidefinite program (MISDP): (1) provide an algorithm for computing optimal solutions using cutting plane methods; (2) develop lower bounds by posing the problem as a binary semidefinite program; and (3) construct feasible solutions using heuristics and estimate their quality. The network synthesis problem is a nondeterministic polynomial--time (NP)-hard problem. We provide some computational results to corroborate the performance of the proposed algorithms.
Dissipation of fast strike-slip faulting within and beyond northeastern Tibet

Structural patterns, global positioning system (GPS) velocities, and Quaternary fault slip rates in northeastern Tibet indicate a transfer of left-lateral slip from the Kunlun fault northeast to the Haiyuan fault and minor crustal shortening and rotation within a 200-km-wide stepover zone. Related deformation also continues at least a few hundred kilometers north of the Haiyuan fault into a region of diffuse extensional(?) shear or rotation underlain by average thickness crust. Fast, localized slip along the central Kunlun fault transforms into distributed deformation across a 500-km-wide zone where the lower crust is weak. The distribution of fault-parallel GPS velocities across this region suggests a decrease in fault slip toward eastern fault tips and progressive dissipation of slip to the north rather than east of the Tibetan Plateau as previously suggested.
Team cohesion effects on business game performance

Numerous relationships between student team cohesion and its effects on simulated company performance were hypothesized and tested within a fairly complex business game. Cohesion was both directly and indirectly related to a teamâ€™s economic effectiveness.
DIRC, a new type of particle identification system For BABAR

The DIRC, a new type of Cherenkov imaging device, has been selected as the primary particle identification system for the BABAR detector at the asymmetric B-factory, PEP-II. It is based on total internal reflection and uses long, rectangular bars made from synthetic fused silica as Cherenkov radiators and light guides. In this paper, the principles of the DIRC ring imaging Cherenkov technique are explained and results from the prototype program are presented. The studies of the optical properties and radiation hardness of the quartz radiators are described, followed by a discussion of the detector design.
The structural characteristics of inflatable beams

Abstract The use of pneumatic architecture has historically been limited because of its poor performance in the areas of strength and rigidity. Yet the advent of new high strength fibers such as Allied Signal's “Spectra 1000” composed of ultra-high molecular weight polyethylene offer hope for the expanded use of inflatable structures. This thesis involved the design, construction and stiffness testing of two inflatable beams fashioned from Spectra cloth. The test data and calculations indicated that the prototype tubes were neither as strong or stiff as rigid composite or metal alloy tubes. The tubes did, however, show an improvement over the capabilities of conventional inflatable tubes fashioned from nylon or dacron fabrics. The data from the deflection tests offered insight on the non-linear and anisotropic behavior of fabrics. The data interpretation process was quite educational for the author, for he learned that nearly every assumption he held and theory postulated concerning the behavior of fabric beams - based on his knowledge of isotropic materials - varied from somewhat to quite inaccurate. This project has increased the author's interest in inflatable structures and has highlighted the importance of understanding the behavior of textiles for effective design efforts.
Environmental Public Health Applications Using Remotely Sensed Data

We describe a remote sensing and geographic information system (GIS)-based study that has three objectives: (1) characterize fine particulate matter (PM2.5), insolation and land surface temperature (LST) using NASA satellite observations, Environmental Protection Agency (EPA) ground-level monitor data and North American Land Data Assimilation System (NLDAS) data products on a national scale; (2) link these data with public health data from the REasons for Geographic And Racial Differences in Stroke (REGARDS) national cohort study to determine whether these environmental risk factors are related to cognitive decline, stroke and other health outcomes and (3) disseminate the environmental datasets and public health linkage analyses to end users for decision-making through the Centers for Disease Control and Prevention (CDC) Wide-ranging Online Data for Epidemiologic Research (WONDER) system. This study directly addresses a public health focus of the NASA Applied Sciences Program, utilization of Earth Science...
Transseries and Todorov---Vernaeve's asymptotic fields

We study the relationship between fields of transseries and residue fields of convex subrings of non-standard extensions of the real numbers. This was motivated by a question of Todorov and Vernaeve, answered in this paper.
Global General Relativistic Magnetohydrodynamic Simulations of Accretion Tori

This paper presents an initial survey of the properties of accretion flows in the Kerr metric from three-dimensional, general relativistic magnetohydrodynamic simulations of accretion tori. We consider three fiducial models of tori around rotating, both prograde and retrograde, and nonrotating black holes; these three fiducial models are also contrasted with axisymmetric simulations and a pseudo-Newtonian simulation with equivalent initial conditions, to delineate the limitations of these approximations. There are both qualitative and quantitative differences in the fiducial models, with many of these effects attributable to the location of the marginally stable orbit, rms(a), both with respect to the initial torus and in absolute terms. In the retrograde model, the initial inner edge of the torus is close to rms, and little angular momentum need be lost to drive accretion, whereas in the prograde case the gas must slowly accrete over a significant distance and shed considerable angular momentum. Evolution is driven by the magnetorotational instability and the nonzero Maxwell stresses produced by the turbulence and results in a redistribution of the specific angular momentum to near-Keplerian values. The magnetic energy remains subthermal within the turbulent disk, but dominates in the final plunging flow into the hole. The Maxwell stress remains nonzero in this plunging flow inside of rms, and the fluid's specific angular momentum continues to drop. The accretion rate into the hole is highly time-variable and is determined by the rate at which gas from the turbulent disk is fed into the plunging flow past rms. The retrograde model, with the largest rms, shows the least variability in accretion rate. While accretion variability is a function of a, the turbulence itself is also intrinsically variable. A magnetized, backflowing corona and an evacuated, magnetized funnel are features of all models.
Lobatamide C: Total Synthesis, Stereochemical Assignment, Preparation of Simplified Analogues, and V-ATPase Inhibition Studies

The total synthesis and stereochemical assignment of the potent antitumor macrolide lobatamide C, as well as synthesis of simplified lobatamide analogues, is reported. Cu(I)-mediated enamide formation methodology has been developed to prepare the highly unsaturated enamide side chain of the natural product and analogues. A key fragment coupling employs base-mediated esterification of a β-hydroxy acid and a salicylate cyanomethyl ester. Three additional stereoisomers of lobatamide C have been prepared using related synthetic routes. The stereochemistry at C8, C11, and C15 of lobatamide C was assigned by comparison of stereoisomers and X-ray analysis of a crystalline derivative. Synthetic lobatamide C, stereoisomers, and simplified analogues have been evaluated for inhibition of bovine chromaffin granule membrane V-ATPase. The salicylate phenol, enamide NH, and ortho-substitution of the salicylate ester have been shown to be important for V-ATPase inhibitory activity.
GEODESICS IN RANDERS SPACES OF CONSTANT CURVATURE

Geodesies in Randers spaces of constant curvature are classified. Randers metrics have received much attention lately as solutions to Zermelo's problem of navigation; largely because this navigation structure provides the frame work for a complete classification of constant flag curvature Randers spaces. (Flag curvature is the Finslerian analog of Riemannian sectional curvature. See (BR04).) Briefly, a Randers metric is of constant flag curvature if and only if it solves Zer melo's problem of navigation on a Riemannian manifold of constant sectional cur vature under the influence of an infinitesimal homothety W. See Subsection 1.1 for a sketch of the navigation problem, and Theorem 3 for an explicit statement of the classification result. The aim of this paper is to develop a geometric description of the geodesies in these spaces of constant curvature. Intuitively, these paths minimize travel time across a Riemannian landscape under windy conditions. Presently we will show that these curves are given by composing geodesies of the Riemannian metric with the flow generated by W. This claim is formalized by Theorem 2. Geodesies on surfaces of constant, nonpositive curvature are illustrated in Section 3. We then turn, in Section 4, to the constant flag curvature K = 1 Randers metrics on Sn. The case of the sphere is especially interesting; it is possible to endow this closed manifold with a metric whose geodesies display distinctly non-Riemannian behaviors. For example: (1) A metric is projectively flat if every point admits coordinates in which the geodesies are straight lines. Belt r ami's theorem assures us that a Riemannian metric is of constant sectional curvature if and only if it is projectively flat. In contrast few Randers spaces of constant flag curvature are projectively flat. There are infinitely many nonisometric Randers metrics of constant, positive
Autologous Blood Donation

Preoperative autologous blood donation has become accepted as a standard practice in elective surgery. Subsequent improvements in blood safety and evolving surgical techniques resulting in less blood loss have caused a national decline in preoperative autologous blood donation by approximately 50%. Nevertheless, the continuing emergence of new pathogens and the potential for severe blood inventory shortages continue to give preoperative autologous blood donation an important role in blood conservation strategies.