cssi/SciSciGPT-SciSciNet huggingface dataset:
Correlation and Volatility Dynamics in REIT Returns: Performance and Portfolio Considerations

In this article, the authors examine the dynamics of the correlation and volatility of REITs, stocks, and direct real estate returns using monthly data from January 1987 to May 2008. In order to explore asymmetries in conditional correlation, the authors use a multivariate asymmetric dynamic diagonal conditional correlation (AD-DCC) GARCH specification. They document that the time-varying conditional correlations can be explained by macroeconomic variables, such as term and credit spreads, inflation, and the unemployment rate, and they find a strong relationship between correlations and REIT returns and that the patterns are distinguishable for different types of REITs. Interestingly, when the correlation between REITs and the SP that is, the higher (lower) correlation between equity REITs and direct real estate, the higher (lower) the future returns of equity REITs. The authors’ results have economic implications regarding the time-dependent diversification benefits of REITs in a mixed-asset portfolio and the unique risk and return characteristics of REITs.
Residential Asking Rents and Time on the Market

Landlords offering a house in the rental market face a difficult strategic pricing decision. The revenue maximizing decision for the landlord involves a tradeoff between the rental rate and time on the market. Because the turnover of renters is higher than owners, and because the landlord must bear some carrying costs on a vacant house, pricing the rent too high may decrease revenue due to a higher vacancy period and pricing it too low may reduce the revenue when occupied. While there is substantial research on the relationship between listed prices and time on the market for freehold interests, this is the first study to provide empirical evidence on the relationship between asking rent, contract rent and time on the market for single family residential rental (leasehold) property interests. We present two models; a rental price model and a duration model for time-on-the market. Using data from the Dallas-Fort Worth area we find that landlords who set a lower asking rent relative to predicted rent can expect a shorter marketing period for their properties. The results also indicate that overpricing the asking rent and then lowering it at a later date leads to a longer marketing time (after the reset) and often a lower rent. These finding are reasonably robust for low-, mid-, and higher-valued rental properties.
Linear Numerical-Magnitude Representations Aid Children’s Memory for Numbers

We investigated the relation between children's numerical-magnitude representations and their memory for numbers. Results of three experiments indicated that the more linear children's magnitude representations were, the more closely their memory of the numbers approximated the numbers presented. This relation was present for preschoolers and second graders, for children from low-income and middle-income backgrounds, for the ranges 0 through 20 and 0 through 1,000, and for four different tasks (categorization and number-line, measurement, and numerosity estimation) measuring numerical-magnitude representations. Other types of numerical knowledge-numeral identification and counting-were unrelated to recall of the same numerical information. The results also indicated that children's representations vary from trial to trial with the numbers they need to represent and remember and that general strategy-choice mechanisms may operate in selection of numerical representations, as in other domains.
Regional conductance changes during hemorrhage in pregnant and nonpregnant conscious rabbits.

Late pregnant (P) conscious rabbits are less able to maintain arterial pressure during hemorrhage than nonpregnant (NP) animals. This study tested the hypothesis that the difference is due in part ...
Adaptive rate error control through the use of diversity combining and majority-logic decoding in a hybrid-ARQ protocol

Diversity combining and majority-logic decoding are combined to create a simple but powerful hybrid automatic repeat request (ARQ) error control scheme. Forward-error-correcting (FEC) majority-logic decoders are modified for use in type-I hybrid-ARQ protocols through the identification of reliability information within the decoding process. Diversity combining is then added to reduce the number of retransmissions and their consequent impact on throughput performance. Packet combining has the added benefit of adapting the effective code rate to channel conditions. Excellent reliability performance coupled with a simple high-speed implementation makes the majority-logic system and ideal choice for high-data-rate error control over both stationary and nonstationary channels. >
Ab initio molecular dynamics simulations of the initial stages of solid–electrolyte interphase formation on lithium ion battery graphitic anodes

The decomposition of ethylene carbonate (EC) during the initial growth of solid–electrolyte interphase (SEI) films at the solvent–graphitic anode interface is critical to lithium ion battery operations. Ab initio molecular dynamics simulations of explicit liquid EC/graphite interfaces are conducted to study these electrochemical reactions. We show that carbon edge terminations are crucial at this stage, and that achievable experimental conditions can lead to surprisingly fast EC breakdown mechanisms, yielding decomposition products seen in experiments but not previously predicted.
Scenario-based prototyping for requirements identification

The three major facets of software requirements engineering are: (1) requirements identification, (2) requirements analysis, and (3) requirements communication. Much research addresses the latter two aspects, but few practical approaches exist for addressing the first one. Hence, system requirements remains the most critical and problemprone area of system development. There is thus an urgent need for a methodology which helps a user identify requirements and realize potential impacts, in a timely manner.The objectives of this research are: (1) develop a methodology (and accompanying tools) to aid users in identifying requirements before building a system, and (2) evaluate the effectiveness of the methodology (and tools) in actual use.The novel approach of this research is an attempt to capture the conceptual system as visualized by the user, by use of operational examples ("scenarios"). By means of simulation and man-machine interface techniques, the scenarios may serve as a "quick and dirty" prototype of the intended system, providing the means for requirements analysis and validation, and for communicating the real intent of the requirements. It is anticipated that the methodology can be extended to fully support the concept of step-wise refinement and continuing system validation.
THE CHERN–SIMONS–LANDAU–GINZBURG THEORY OF THE FRACTIONAL QUANTUM HALL EFFECT

This paper gives a systematic review of a field theoretical approach to the fractional quantum Hall effect (FQHE) that has been developed in the past few years. We first illustrate some simple physical ideas to motivate such an approach and then present a systematic derivation of the Chern–Simons–Landau–Ginzburg (CSLG) action for the FQHE, starting from the microscopic Hamiltonian. It is demonstrated that all the phenomenological aspects of the FQHE can be derived from the mean field solution and the small fluctuations of the CSLG action. Although this formalism is logically independent of Laughlin's wave function approach, their physical consequences are equivalent. The CSLG theory demonstrates a deep connection between the phenomena of superfluidity and the FQHE, and can provide a simple and direct formalism to address many new macroscopic phenomena of the FQHE.
MASSIVE SATELLITES OF CLOSE-IN GAS GIANT EXOPLANETS

We study the orbits, tidal heating and mass loss from satellites around close-in gas giant exoplanets. The focus is on large satellites which are potentially observable by their transit signature. We argue that even Earth-size satellites around hot Jupiters can be immune to destruction by orbital decay; detection of such a massive satellite would strongly constrain theories of tidal dissipation in gas giants, in a manner complementary to orbital circularization. The star's gravity induces significant periodic eccentricity in the satellite's orbit. The resulting tidal heating rates, per unit mass, are far in excess of Io's and dominate radioactive heating out to planet orbital periods of months for reasonable satellite tidal Q. Inside planet orbital periods of about a week, tidal heating can completely melt the satellite. Lastly, we compute an upper limit to the satellite mass loss rate due to thermal evaporation from the surface, valid if the satellite's atmosphere is thin and vapor pressure is negligible. Using this upper limit, we find that although rocky satellites around hot Jupiters with orbital periods less than a few days can be significantly evaporated in their lifetimes, detectable satellites suffer negligible mass loss at longer orbital periods.
Maximizing the number of q-colorings

Let PG(q) denote the number of proper q-colorings of a graph G. This function, called the chromatic polynomial of G, was introduced by Birkhoff in 1912, who sought to attack the famous four-color problem by minimizing PG(4) over all planar graphs G. Since then, motivated by a variety of applications, much research was done on minimizing or maximizing PG(q )o ver various families of graphs. In this paper, we study an old problem of Linial and Wilf, to find the graphs with n vertices and m edges which maximize the number of q-colorings. We provide the first approach that enables one to solve this problem for many nontrivial ranges of parameters. Using our machinery, we show that for each q 4 and sufficiently large m<κ qn 2 ,w hereκq ≈ 1/(q log q), the extremal graphs are complete bipartite graphs minus the edges of a star, plus isolated vertices. Moreover, for q = 3, we establish the structure of optimal graphs for all large m n 2 /4, confirming (in a stronger form) a conjecture of Lazebnik from 1989.
Voltages across an area of a network

Summary form only given. We define the voltage across an area of a resistive network by suitably combining voltages at buses (nodes) on the border of the area. The new voltage across the area satisfies circuit laws. The same concept works to define the voltage angle difference across an area of a DC load flow network and the complex voltage difference across an area of an AC load flow network. We first define the voltage across a cutset of lines, and then derive and explain the voltages across areas, including generalizations to several voltages across an area and multiple areas. The new voltages across areas seem promising for both power system monitoring and network reduction, and we describe their application to monitoring area stress.
General wellbore flow model for horizontal, vertical, and slanted well completions

A general wellbore flow model, which incorporates not only frictional, accelerational, and gravitational pressure drops, but also the pressure drop caused by inflow, is presented in this paper. The new wellbore model is readily applicable to different wellbore perforation patterns and well completions, and can be easily incorporated in reservoir simulators or analytical reservoir inflow models. Three dimensionless numbers, the accelerational to frictional pressure gradient ratio R{sub af}, the gravitational to frictional pressure gradient ratio R{sub gf}, and the inflow-directional to accelerational pressure gradient ratio R{sub da}, have been introduced to quantitatively describe the relative importance of different pressure gradient components. For fluid flow in a production well, it is expected that there exist three different flow regions along the wellbore, the laminar flow region, the partially-developed turbulent flow region, and the fully-developed turbulent flow region. For wellbore flow with uniform influx, R{sub af} in the laminar flow region is a constant which is only dependent on fluid properties, inflow rate and pipe ID, but independent of axial location and pipe roughness; R{sub af} in the fully-developed turbulent flow region is related to the axial location and pipe geometry (pipe ID and pipe roughness) and may be independent of themore » fluid properties and inflow rate; whereas R{sub af} in the partially- developed turbulent flow region depends on location, pipe geometry, fluid properties and inflow rate. It is found that the influence of either inflow or outflow depends on the flow regime present in the wellbore. It is recommended that the new wellbore flow model be included in wellbore-reservoir coupling models to achieve more accurate predictions of pressure drop and inflow distribution along the wellbore as well as the well production or injection rates.« less
Ten Micron Observations of Nearby Young Stars

We present new 10 μm photometry of 21 nearby young stars obtained at the Palomar 5 m and at the Keck I 10 m telescopes as part of a program to search for dust in the habitable zone of young stars. Thirteen of the stars are in the F-K spectral type range ("solar analogs"), four have B or A spectral types, and four have spectral type M. We confirm existing IRAS 12 μm and ground-based 10 μm photometry for 10 of the stars and present new insight into this spectral regime for the rest. Excess emission at 10 μm is not found in any of the young solar analogs, except for a possible 2.4 σ detection in the G5 V star HD 88638. The G2 V star HD 107146, which does not display a 10 μm excess, is identified as a new Vega-like candidate, based on our 10 μm photospheric detection, combined with previously unidentified 60 and 100 μm IRAS excesses. Among the early-type stars, a 10 μm excess is detected only in HD 109573A (HR 4796A), confirming prior observations; among the M dwarfs, excesses are confirmed in AA Tau, CD -40°8434, and Hen 3-600A. A previously suggested N-band excess in the M3 dwarf CD -33°7795 is shown to be consistent with photospheric emission. We calculate infrared to stellar bolometric luminosity ratios for all stars exhibiting mid-infrared excesses and infer the total mass of orbiting dust in the cases of optically thin disks. For a derived median photometric precision of ±0.11 mag, we place an upper limit of M_(dust) ≈ 2 × 10^(-5) M_⊕ on the dust mass (assuming a dust temperature of 300 K) around solar analogs not seen in excess at 10 μm. Our calculations for the nearby K1 V star HD 17925 show that it may have the least massive debris disk known outside our solar system (M_(dust) ≳ 7 × 10^(-6) M_⊕). Our limited data confirm the expected tendency of decreasing fractional dust excess f_d = L_(IR)/L^* with increasing stellar age. However, we argue that estimates of f_d suffer from a degeneracy between the temperature and the amount of circumstellar dust M_(dust), and we propose a relation of M_(dust) as a function of age instead.
Wave breakdown in stratified shear flows

The wave-mechanical condition (Landahl 1972) for breakdown of an unsteady laminar flow into strong small-scale secondary instabilities is applied to some simple stratified inviscid shear flows. The cases considered have one or two discrete density interfaces and simple discontinuous or continuous velocity profiles. A primary wavelike disturbance to such a flow produces a perturbation velocity that is discontinuous at a density interface. The resulting instantaneous system, defined as the sum of the mean flow and the primary oscillation, develops a local secondary shear-flow instability that has a group velocity equal to the arithmetic mean of the instantaneous velocities on the two sides of the interface. According to the breakdown criterion, the disturbed flow will become critical whenever this velocity reaches a value equal to the phase velocity of the primary wave. The calculations show that for a single density interface breakdown may occur for low to moderate wave amplitudes in a fairly narrow range of Richardson numbers on the stable side of the stability boundary. On the other hand, in the unstable regime maximum wave slopes of order unity may be reached before breakdown occurs; this conclusion is in qualitative agreement with experiments. When the system includes two density interfaces, it is found that there exists a range of high Richardson numbers far into the stable regime for which breakdown may take place even for very small and zero wave interface deflexions.
A 100-kV hydrogen thyratron without gradient grids

A high-power hydrogen thyratron grid-anode structure has been developed using a 5949 thyratron cathode assembly. One such device was operated for 10 h at 2000 A, 32 kV, at 1400 pps with a pulse width of 0.3 µs. Another was operated for periods up to 220 h at 1000 A, 100 kV, at a duty cycle of 0.00004. The duty cycle is presently limited by our test modulator circuit. Trigger requirements are 2 kV at 50 Ω with a 2.5-µs duration. The jitter was nil when measured with a Tektronix 517 oscilloscope using a sweep speed of 50 ns/cm. The anode delay time is in the range of 1/4 to 1/2/ µs. The grid-anode geometry is designed for a minimum anode-grid capacity, thus providing a tube with a higher repetition rate capability. The field emission limit up to 100 kV is not evident in the normal sense in this geometry.
Longitudinal control algorithm for automated vehicle merging

This paper considers longitudinal control of automated vehicle merging in a mathematical approach for automated highway systems. Merging manoeuvre is defined as one vehicle in the merging lane to be inserted in the middle between two vehicles in the main lane at fixed merging point which is the intersection of those two lanes. The main lane vehicles can change speed. To achieve this, the merging vehicle must properly adjust its speed and acceleration such that it reaches the merging point at the right time with the same speed and acceleration as the main lane vehicles. This problem is a little similar to but different from the well-known missile interception problem. The longitudinal control problem is proposed for different road layouts, based on which a unified mathematical model is established. Then a new concept, virtual platooning, is introduced, which effectively avoids a two-point boundary value problem . Based on this concept, an analytic solution with mathematical proof is provided. It is also di...
North American design guidelines for concrete reinforcement and strengthening using FRP: principles, applications and unresolved issues

Abstract This paper reports on the North American state-of-the-art in the use of FRP composites in concrete structures. For new construction, FRP bars have been used as the internal reinforcement in concrete members to replace conventional steel rebars for a host of reasons. The principles for design and construction have been established and proposed to industry by the American Concrete Institute (ACI). For repair and upgrade, strengthening of concrete members with externally bonded FRP laminates or near surface mounted (NSM) bars has received remarkable attention. The design and construction principles for use in practice are being finalized by ACI. On the application side, FRP materials have been used in some multi-million dollar projects for strengthening parking garages, multi-purpose convention centers, office buildings and silos. The drivers for this technology are several, but perhaps the most relevant one is the ease of installation. In the repair/upgrade arena (as well as new construction), perhaps one of the most important unresolved question remains that of durability (including fire resistance). Further research and validation is necessary to increase confidence in FRP technology for concrete construction.
Modern approaches to conceptualizing and measuring human life stress.

The idea that adverse life circumstances and negative life events contribute to disorder and disease has long been held. Advances in conceptualizing and defining these conditions under the common label of life stress have led to progress in measuring both the environmental and individual response characteristics that may promote disorder and disease. In general, a substantial and growing research literature supports the basic premise that life stress plays an important role in the development of many psychological and physical problems. Recent research, too, strongly suggests that interest in life stress in relation to health and disease will accelerate over the coming years. Yet debates and controversies remain concerning how to best conceptualize and measure life stress, which presents distinctive challenges for advancing the field. The present review examines the major issues pertaining to these debates, controversies, and challenges, for they will be crucial to resolve if progress is to be made in und...
Finding the optimal variable ordering for binary decision diagrams

The ordered binary decision diagram is a canonical representation for Boolean functions, presented by R.E. Bryant (1985) as a compact representation for a broad class of interesting functions derived from circuits. However, the size of the diagram is very sensitive to the choice of ordering on the variables; hence, for some applications, such as differential cascode voltage switch (DCVS) trees, it becomes extremely important to find the ordering leading to the most compact representation. An algorithm for this problem with time complexity O(n/sup 2/3/sup n/) is presented. This represents an improvement over the previous best algorithm. >
Using Budgets for Performance Evaluation: Effects of Resource Allocation and Horizontal Information Asymmetry on Budget Proposals, Budget Slack, and Performance

Business executives and academics frequently criticize budget‐based compensation plans as providing incentives for subordinates to build slack into proposed budgets. In this paper, we examine whether either of two practices—using budgets to allocate scarce resources, or providing information about co‐workers—reduces budget slack and increases subordinate performance when organizations use budgets for performance evaluation. The results from our experiment show that using budgets for both resource allocation and performance evaluation not only eliminates budget slack, but also increases subordinates' effort and task performance. Additionally, we find that an internal reporting system that provides information about subordinates' budgets and performance to their co‐workers mitigates budget slack when superiors do not use budgets as a basis for resource allocation. These results highlight the synergies between the planning (resource allocation) and control (performance evaluation) functions of managerial acc...
Physical properties of very powerful FRII radio galaxies

Aims. We estimate the ages and physical properties of powerful radio galaxies. Methods. An analysis of new multi-wavelength VLA observations of eleven very powerful classical double (FRIIb) radio galaxies with redshifts between 0.4 and 1.3 is presented. We estimate ages and velocities for each side of each source. The eleven new sources are combined with previously studied samples and the characteristics of the full sample of 31 sources are studied; the full sample includes sources with redshifts between 0.056 and 1.79, and core-hot spot sizes of about 30 to 400 kpc. Results. The velocities are independent of core-hotspot separation, suggesting the rate of growth of a given source is roughly constant over the source lifetime. We combine the rate of growth, width, and pressure of a source to study the beam power, lifetime, energy, and ambient gas density using standard methods previously applied to smaller samples. Typical beam powers are in the range from 10 44 to 10 46 erg/s; we show that this quantity is insensitive to assumptions regarding minimum energy conditions. The beam powers are independent of core-hotspot separation suggesting that the beam power of a given source is roughly constant over the source lifetime. Typical total source lifetimes are found to be about a few ×(10 6 −10 7 ) years, and typical total outflow energies (E/c 2 ) are found to be about 5 × (10 5 −10 6 ) M� . Ambient gas densities are found to decrease with increasing core-hotspot distance, but have no redshift dependence. Overall, the results obtained with the sample of 31 sources studied here are consistent with those obtained earlier with smaller samples.
The republic of Congo's infrastructure : a continental perspective

Infrastructure contributed half a percentage point to the Republic of Congo's annual per capita GDP growth from 2001 to 2006. If the country's infrastructure were improved to the level seen in Mauritius, the regional leader, it could contribute more than 3 percentage points to annual per capita growth. The Republic of Congo's existing infrastructure is concentrated in the developed south, reflecting the country's urbanization patterns. Links spread from there to the less-developed north, where there are vast areas of underexploited dense forest. The Republic of Congo's power sector offers the greatest potential for infrastructure-based economic growth, but major inefficiencies need to be addressed. Transit improvements would also make significant contributions to growth by improving connections to the north and to neighboring countries. Additional opportunities include rehabilitating the fixed-line telephone operator to spread Internet access. The country's water and sanitation infrastructure is in relatively good shape. Spending on infrastructure was $460 million per year in the Republic of Congo during the mid-2000s. Based on these spending levels, if all inefficiencies were eliminated, the country would face an infrastructure funding gap of $270 million a year and would not meet infrastructure targets for 31 years. Spending rose to $550 million per year in 2008-09. If the Republic of Congo could maintain these higher spending levels, the funding gap would essentially disappear. The nation could further reduce the funding gap by adopting lower-cost technologies to meet infrastructure targets.
COMPRESSION OF EPHEMERIDES BY DISCRETE CHEBYSHEV APPROXIMATIONS

The emergence of satellite navigation has brought about the need for compact representations of satellite ephemerides. Polynomial representations offer several advantages. Polynomial representations of navigational and astronomical ephemerides are usually derived from discrete least squares approximations. However, to ensure a uniform distribution of the error, one should aim at a continuous Chebyshev approximation, whereby the maximum error in absolute value taken over the entire interval is minimized. This is feasible when the ephemeris is generated from a literal (analytical or semi-analytical) development. But a discrete Chebyshev approximation, whereby the maximum error in absolute value is considered only over a finite set of reference points in the interval, is a realistic compromise. Application to the moon and geosynchronous satellites has given good results. On the whole, long ranges (several times the sidereal period) may be covered by polynomials of degree 30 to 50 with a moderate error. A low degree approximation over half the period usually delivers a high accuracy. Gibbs' phenomena, i.e. rapid oscillations of increasing amplitudes in the error curve at both ends of the approximation interval are of course absent, contrary to what happens usually in a least squares approximation.
STRUCTURE AND FEEDBACK IN 30 DORADUS. II. STRUCTURE AND CHEMICAL ABUNDANCES

We use our new optical-imaging and spectrophotometric survey of key diagnostic emission lines in 30 Doradus, together with CLOUDY photoionization models, to study the physical conditions and ionization mechanisms along over 4000 individual lines of sight at points spread across the face of the extended nebula, out to a projected radius 75 pc from R136 at the center of the ionizing cluster NGC 2070. We focus on the physical conditions, geometry, and importance of radiation pressure on a point-by-point basis, with the aim of setting observational constraints on important feedback processes. We find that the dynamics and large-scale structure of 30 Dor are set by a confined system of X-ray bubbles in rough pressure equilibrium with each other and with the confining molecular gas. Although the warm (10,000 K) gas is photoionized by the massive young stars in NGC 2070, the radiation pressure does not currently play a major role in shaping the overall structure. The completeness of our survey also allows us to create a composite spectrum of 30 Doradus, simulating the observable spectrum of a spatially unresolved, distant giant extragalactic Hii region. We find that the highly simplified models used in the “strong line” abundance technique do in fact reproduce our observed line strengths and deduced chemical abundances, in spite of the more than one order of magnitude range in the ionization parameter and density of the actual gas in 30 Dor.
Use of psychotropic drugs before pregnancy and the risk for induced abortion: population-based register-data from Finland 1996-2006

Background Some, though not all studies have reported an increased risk for mental health problems after an induced abortion. Problems with design and data have compromised these studies and the generalisation of their results.
Recession behavior of graphitic nozzles in simulated rocket motors

A has been conducted to predict nozzle recession behavior in two different rocket motors and for broad variations of propellant formulations and motor operating conditions. Results show that the recession rate is largely determined by the diffusion of the major oxidizing species (H2O and CO2) to the nozzle surface. The free volume in the motor, the concentration of the major oxidizing species as affected by the aluminum content of the propellant, and the chamber pressure exert a strong influence on the recession rate. A correlation to predict the throat recession in terms of the above governing parameters has been developed. This correlation is in good agreement with experimental data in the two different motors considered.
Example of two different potentials which have practically the same fixed-energy phase shifts

Abstract The Newton-Sabatier procedure for finding the potential from fixed-energy phase shifts is analyzed. A method is proposed for finding two quite different spherically-symmetric real-valued, piecewise-constant, compactly supported potentials which generate at a fixed energy the phase shifts δ l which are practically indistinguishable for all l. In particular, an explicit concrete example of two such potentials q j , j = 1,2 is demonstrated. These potentials have the properties: (1) sup | q 1 1 − q 2 | > 3, and q j , j = 1,2, are of order of magnitude 1, (2) δ l (1) = δ l (2) for l = 0, …,4 and | δ l (1) − δ l (2) | ≤ 10 −5 , l > 4.
Optimized piezoelectric energy harvesting circuit using step-down converter in discontinuous conduction mode

An optimized method of harvesting vibrational energy with a piezoelectric element using a step-down DC-DC converter is presented. In this configuration, the converter regulates the power flow from the piezoelectric element to the desired electronic load. Analysis of the converter in discontinuous current conduction mode results in an expression for the duty cycle-power relationship. Using parameters of the mechanical system, the piezoelectric element, and the converter; the "optimal" duty cycle can be determined where the harvested power is maximized for the level of mechanical excitation. It is shown that, as the magnitude of the mechanical excitation increases, the optimal duty cycle becomes essentially constant, greatly simplifying the control of the step-down converter. The expression is validated with experimental data showing that the optimal duty cycle can be accurately determined and maximum energy harvesting attained. A circuit is proposed which implements this relationship, and experimental results show that the converter increases the harvested power by approximately 325%.
Finding Deceptive Opinion Spam by Any Stretch of the Imagination

Consumers increasingly rate, review and research products online (Jansen, 2010; Litvin et al., 2008). Consequently, websites containing consumer reviews are becoming targets of opinion spam. While recent work has focused primarily on manually identifiable instances of opinion spam, in this work we study deceptive opinion spam---fictitious opinions that have been deliberately written to sound authentic. Integrating work from psychology and computational linguistics, we develop and compare three approaches to detecting deceptive opinion spam, and ultimately develop a classifier that is nearly 90% accurate on our gold-standard opinion spam dataset. Based on feature analysis of our learned models, we additionally make several theoretical contributions, including revealing a relationship between deceptive opinions and imaginative writing.
Formation of X-Ray Cavities by the Magnetically Dominated Jet-Lobe System in a Galaxy Cluster

We present cosmological magnetohydrodynamic simulations of the formation of a galaxy cluster with magnetic energy feedback from an active galactic nuclei (AGNs). We demonstrate that X-ray cavities can be produced by the magnetically dominated jet-lobe system that is supported by a central axial current. The cavities are magnetically dominated, and their morphology is determined jointly by the magnetic fields and the background cluster pressure profile. The expansion and motion of the cavities are driven initially by the Lorentz force of the magnetic fields, and the cavities only become buoyant at late stages (>500 Myr). We find that up to 80%-90% of the injected magnetic energy goes into doing work against the hot cluster medium, heating it, and lifting it in the cluster potential.
Extremum seeking methods for optimization of variable cam timing engine operation

Automotive engines have been increasingly equipped with devices that can vary engine parameters with operating conditions. Optimizing these parameters via standard engine mapping and calibration has become a very time consuming task. The specific problem under consideration in this paper is optimization of intake, exhaust, and spark timings to improve the brake specific fuel consumption of a dual-independent variable cam timing engine. We have explored extremum seeking (ES) as a method to find the optimal setting of the parameters. During ES, the engine is running at fixed speed and torque in a dynamometer test cell, while an optimization algorithm is iteratively adjusting the three parameters. For our purposes, we have modified several algorithms available in the literature. The details about the algorithms and the experimental results they produced are presented and discussed in the paper.
Lasers in Earth and planetary exploration

For over 3 decades lasers have been a tool of the space programs of the world for accomplishing a variety of engineering and scientific objectives. The majority of these uses have, however, been largely Earth-based and only a few lasers have actually been flown and operated in Earth orbit and even fewer on missions to the planets. However, in the last few years laser altimeters, lidars, and ranging systems have been part of space missions to the Moon, an asteroid, and Mars; and more are planned and contemplated in the future exploration of the solar system. On September 11, 1997 the Mars Global Surveyor (MGS) entered into orbit around Mars. One of the four scientific instruments on MGS is the Mars Orbiter Laser Altimeter (MOLA) which has started to map the topography of the planet to unprecedented accuracy. In January 1999 the NEAR Spacecraft, which carries a laser ranger (NLR), will arrive at the asteroid Eros and over the period of a year the NLR will determine the shape and the dynamics of the body. MOLA and NLR, along with the Clementine laser altimeter that went to the Moon in 1992 and changed many of our perceptions of the Moon, represent a new class of active remote sensing instruments for conducting science in the solar system. With them and their successors we can begin to unravel many of the intriguing questions surrounding the formation, dynamics and evolution of the planets, and even the solar system itself. Data recently acquired at Mars, around Earth and Moon, and ideas for the future will be presented in the context of what we are learning about Earth and our nearest neighbors.
Quarkonium at nonzero isospin density

We calculate the energies of quarkonium bound states in the presence of a medium of nonzero isospin density using lattice QCD. The medium, created using a canonical (fixed isospin charge) approach, induces a reduction of the quarkonium energies. As the isospin density increases, the energy shifts first increase and then saturate. The saturation occurs at an isospin density close to that where previously a qualitative change in the behavior of the energy density of the medium has been observed, which was conjectured to correspond to a transition from a pion gas to a Bose-Einstein condensed phase. The reduction of the quarkonium energies becomes more pronounced as the heavy-quark mass is decreased, similar to the behavior seen in two-color QCD at nonzero quark chemical potential. In the process of our analysis, the η{sub b-π} and Υ-π scattering phase shifts are determined at low momentum. An interpolation of the scattering lengths to the physical pion mass gives a{sub η{sub b},π}=0.0025(8)(6) fm and a{sub Υ,π}=0.0030(9)(7) fm.
Catalytic Enantioselective Alkylation of Substituted Dioxanone Enol Ethers: Ready Access to C(α)-Tetrasubstituted Hydroxyketones, Acids, and Esters

Adaptive Alkylation: Palladium-catalyzed asymmetric alkylation enables access to fully substituted enantioenriched oxygenated stereocenters, which can be transformed easily to α-hydroxyketones, esters, and acids, providing a catalytic, enantioselective synthesis for natural products.
Periodic Optical Outbursts from the Be-Neutron Star Binary AX J0049.4−7323*

The optical light curve of the Be–neutron star binary AX J0049.4-7323 has been investigated using data from the MACHO and OGLE-II projects. This X-ray source, whose neutron star has a very slow rotation rate (Ppulse = 755.5 s), shows optical outbursts every ~394 days. The regularity of these outbursts suggests that their recurrence time is the orbital period of the system. During the outbursts, the system brightens and becomes slightly redder. A possible interpretation is that a portion of the equatorial disk is excited as the neutron star passes through it during periastron passage. In the intervals between outbursts, the light curve shows ~11 day quasi-periodic variability, which may be associated with the rotation of the Be star's extended disk.
Miniaturized gas ionization sensors using carbon nanotubes

Gas sensors operate by a variety of fundamentally different mechanisms1,2,3,4,5,6,7,8,9,10,11,12,13,14. Ionization sensors13,14 work by fingerprinting the ionization characteristics of distinct gases, but they are limited by their huge, bulky architecture, high power consumption and risky high-voltage operation. Here we report the fabrication and successful testing of ionization microsensors featuring the electrical breakdown of a range of gases and gas mixtures at carbon nanotube tips. The sharp tips of nanotubes generate very high electric fields at relatively low voltages, lowering breakdown voltages several-fold in comparison to traditional electrodes, and thereby enabling compact, battery-powered and safe operation of such sensors. The sensors show good sensitivity and selectivity, and are unaffected by extraneous factors such as temperature, humidity, and gas flow. As such, the devices offer several practical advantages over previously reported nanotube sensor systems15,16,17. The simple, low-cost, sensors described here could be deployed for a variety of applications, such as environmental monitoring, sensing in chemical processing plants, and gas detection for counter-terrorism.
Active Feature-Value Acquisition

Most induction algorithms for building predictive models take as input training data in the form of feature vectors. Acquiring the values of features may be costly, and simply acquiring all values may be wasteful or prohibitively expensive. Active feature-value acquisition (AFA) selects features incrementally in an attempt to improve the predictive model most cost-effectively. This paper presents a framework for AFA based on estimating information value. Although straightforward in principle, estimations and approximations must be made to apply the framework in practice. We present an acquisition policy, sampled expected utility (SEU), that employs particular estimations to enable effective ranking of potential acquisitions in settings where relatively little information is available about the underlying domain. We then present experimental results showing that, compared with the policy of using representative sampling for feature acquisition, SEU reduces the cost of producing a model of a desired accuracy and exhibits consistent performance across domains. We also extend the framework to a more general modeling setting in which feature values as well as class labels are missing and are costly to acquire.
No Eigenvalue in Finite Quantum Electrodynamics

We re-examine Quantum Electrodynamics (QED) with massless electron as a finite quantum field theory as advocated by Gell-Mann–Low, Baker–Johnson, Adler, Jackiw and others. We analyze the Dyson–Schwinger equation satisfied by the massless electron in finite QED and conclude that the theory admits no nontrivial eigenvalue for the fine structure constant.
Zigzag Chains of Alternating Atoms in A2AuBi (A = Na, K) and K2AuSb. Synthesis, Structure, and Bonding

The polar intermetallic phases A{sub 2}AuBi (A = Na (I), K (II)), and K{sub 2}AuSb (III) were obtained by direct reaction of the elements at elevated temperatures in niobium ampoules. The three isotypic compounds extend the prominent A{sub 2}MPn (M = transition metal; Pn = group 15) structure family. Single-crystal X-ray diffraction experiments show that these phases (I/II/III) crystallize in the orthorhombic space group Cmcm (No. 63), with a = 9.447(2)/10.632(2)/10.450(2) {angstrom}; b = 7.700(2)/7.918(2)/7.857(2) {angstrom}; c = 5.849(1)/6.597(1)/6.501(1) {angstrom}; V = 425.4(2)/555.4(2)/533.8(2) {angstrom}{sup 3}, respectively, and Z = 4. The simple structures, which contain zigzag chains of linear two-bonded gold atoms and acute angles (64 to 76{sup o}) at two-bonded antimony or bismuth, can readily be rationalized with the Zintl-Klemm concept. TB-LMTO calculations show distinct band gaps at EF, and analyses of DOS and COHP curves show optimized Au-Pn bonding, appreciable Au-Au interactions across the chains, and covalent interactions between A and Pn atoms. The observed structural preference over an isoelectronic NaTl type structure, the cation influences, and site coloring were investigated with VASP and EHTB calculations.
Highly enantioselective catalytic acyl-pictet-spengler reactions.

The enantioselective cyclization of N-acyliminium ions generated in situ from tryptamine is promoted with high enantioselectivity by a new chiral thiourea catalyst. This represents the first successful system for asymmetric catalysis of the Pictet−Spengler reaction.
Magnetic nanoparticle sensing: decoupling the magnetization from the excitation field

Remote sensing of magnetic nanoparticles (MNPs) has exciting applications for MNP hyperthermia and molecular detection. We introduce, simulate, and experimentally demonstrate an innovation—a sensing coil that is geometrically decoupled from the excitation field—for MNP spectroscopy that increases the flexibility and capabilities of remote detection. The decoupling enhances the sensitivity absolutely; to small amounts of nanoparticles, and relatively; to small changes in the nanoparticle dynamics. We adapt a previous spectroscopic method that measures the relaxation time of nanoparticles and demonstrate a new measurement of nanoparticle temperature that could potentially be used concurrently during hyperthermia.
Innovation in the public sphere: reimagining law and economics to solve the National Institutes of Health publishing controversy

The National Institutes of Health (NIH) are responsible for the largest proportion of biological science funding in the United States. To protect the public interest in access to publicly funded scientific research, the NIH amended terms and conditions in funding agreements after 2009, requiring funded Principal Investigators to deposit published copies of research in PubMed, an Open Access repository. Principal Investigators have partially complied with this depository requirement, and the NIH have signaled an intent to enforce grant agreement terms and conditions by stopping funding deposits and engaging in legal action. The global economic value of accessible knowledge offers a unique opportunity for courts to evaluate the impact of enforcing 'openness' contract terms and conditions within domestic and international economies for public and economic benefit. Through judicial enforcement of Open Access terms and conditions, the United States can increase economic efficiency for university libraries, academic participants, and public consumers, while accelerating global innovation, improving financial returns on science funding investments, and advancing more efficient scientific publishing models.
Survivorship Differences in Geographical Comparisons of Cancer Mortality: An Urban-Rural Analysis

The survival experience of white male cancer patients residing in rural and urban areas is examined using cancer registry data. The data are for 1178 white U.S. males whose first primary malignancy was recorded between 1977 and 1981. "A multi-variable proportional hazards model is specified to determine the unique effect of geographical residence on survival. Only for cancers of the gastro-intestinal (GI) tract are there statistically significant differences in survivorship by geographical residence. This suggests that for most cancers survival differences are not likely to play a confounding role in geographical comparisons of cancer mortality rates. However for GI cancers survival differences should probably be considered in geographical-oriented analyses and their interpretation." (EXCERPT)
Bridging communications and the physical world: sense everything, control everything

The SECE (Sense Everything, Control Everything) system allows users to create services that combine communication, calendaring, location and devices in the physical world. SECE is an event-driven system that uses a natural-English-like language to trigger action scripts. Presence updates, incoming calls, email, calendar and time events, sensor inputs and location updates can trigger rules. SECE retrieves all this information from multiple sources to personalize services and to adapt them to changes in the user's context and preferences. Actions can control the delivery of email, change the handling of phone calls, update social network status and set the state of actuators such as lights, thermostats and electrical appliances. We give an overview of the SECE language and system architecture.
IMPLICATIONS OF CAPITAL-INTENSIVE DEVELOPMENT INTERVENTIONS FOR COMMUNAL RESOURCE OWNERS: THE CASE OF COMMUNAL FARMERS IN ECUADOR

The introduction in Ecuador of a primary irrigation infrastructure into a communal setting where land users did not fully control the land and had effectively no access to credit, produced a sell off of nearly all irrigable lands. The change in land reservation prices between buyers and sellers is analyzed.