cssi/SciSciGPT-SciSciNet huggingface dataset:
On the asymptotic geometry of abelian-by-cyclic groups

Gromov’s Polynomial Growth Theorem [Gro81] states that the property of having polynomial growth characterizes virtually nilpotent groups among all finitely generated groups. Gromov’s theorem inspired the more general problem (see, e.g. [GdlH91]) of understanding to what extent the asymptotic geometry of a finitelygenerated solvable group determines its algebraic structure—in short, are solvable groups quasi-isometrically rigid? In general they aren’t: very recently A. Dioubina [Dio99] has found a solvable group which is quasi-isometric to a group which is not virtually solvable; these groups are finitely generated but not finitely presentable. In the opposite direction, first steps in identifying quasi-isometrically rigid solvable groups which are not virtually nilpotent were taken for a special class of examples, the solvable BaumslagSolitar groups, in [FM98] and [FM99b]. The goal of the present paper is to show that a much broader class of solvable groups, the class of finitely-presented, nonpolycyclic, abelian-bycyclic groups, is characterized among all finitely-generated groups by its quasi-isometry type. We also give a complete quasi-isometry classification of the groups in this class; such a classification for nilpotent groups remains a major open question. Motivated by these results, we offer a conjectural picture of quasi-isometric classification and rigidity for polycyclic abelianby-cyclic groups in §10.1.
Reducing the Chern–Simons term by a symmetry

Abstract Reducing a 3-dimensional Chern–Simons term by a symmetry yields other topologically interesting structures. Specifically, reducing by radial symmetry results in a 1-dimensional quantum mechanical model, which has recently been used in an analysis of finite-temperature Chern–Simons theory. The radially symmetric expression may be inserted into 3-dimensional monopole or (2+1)-dimensional instanton equations, where it eliminates the monopole or instanton solutions.
Spectra and diagnostics for the direct detection of wide-separation extrasolar giant planets

We calculate as a function of orbital distance, mass, and age the theoretical spectra and orbit-averaged planet/star flux ratios for representative wide-separation extrasolar giant planets (EGPs) in the optical, near-infrared, and mid-infrared. Stellar irradiation of the planet's atmosphere and the effects of water and ammonia clouds are incorporated and handled in a consistent fashion. We include predictions for 12 specific known EGPs. In the process, we derive physical diagnostics that can inform the direct EGP detection and remote sensing programs now being planned or proposed. Furthermore, we calculate the effects of irradiation on the spectra of a representative companion brown dwarf as a function of orbital distance.
Residual interference and wind-tunnel wall adaptation

We review a linear theory of residual interference in adaptive wall wind tunnels. One-variable, two-variable, and interface discontinuity methods are analyzed. Their autocorrective properties and connections with some well-known adaptation criteria, such as the single-step convergence formulas and the functional relationships for unconfined flow, are discussed
Use of Pressure-volume Conductance Catheters in Real-time Cardiovascular Experimentation

Background Most applications of pressure-volume conductance catheter measurements assess cardiovascular function at a single point in time after genetic, pharmacologic, infectious, nutritional, or toxicologic manipulation. Use of these catheters as a continuous monitor, however, is fraught with complexities and limitations. Methods Examples of the limitations and optimal use of conductance catheters as a continuous, real-time monitor of cardiovascular function are demonstrated during inotropic drug infusion in anesthetised rats. Results Inotropic drug infusion may alter ventricular dimensions causing relative movement of a well-positioned catheter, generating artifacts, including an abrupt pressure rise at end-systole that leads to over estimation of indices of contractility (max dP/dt) and loss of stroke volume signal. Simple rotation of the catheter, echocardiography-guided placement to the centre of the ventricle, or ventricular expansion through crystalloid infusion may correct for these artifacts. Fluid administration, however, alters left ventricular end-diastolic pressure and volume and therefore stroke volume, thereby obscuring continuous real-time haemodynamic measurements. Conclusions Pressure-volume artifacts during inotropic infusion are caused by physical contact of the catheter with endocardium. Repeated correction of catheter position may be required to use pressure volume catheters as a continuous real-time monitor during manipulations that alter ventricular dimensions, such as inotropic therapy.
XMM-Newton observations of young and energetic pulsar J2022+3842

We report on XMM-Newton EPIC observations of the young pulsar J2022+3842, with a characteristic age of 8.9 kyr. We detected X-ray pulsations and found the pulsation period P ≈ 48.6 ms, and its derivative , which is two times larger than previously reported values. The pulsar exhibits two very narrow (FWHM ~1.2 ms) X-ray pulses each rotation, separated by ≈0.48 of the period, with a pulsed fraction of ≈0.8. Using the correct values of P and , we calculate the pulsar's spin-down power erg s–1 and magnetic field B = 2.1 × 1012 G. The pulsar spectrum is well modeled with a hard power-law (PL) model (photon index Γ = 0.9 ± 0.1, hydrogen column density n H = (2.3 ± 0.3) × 1022 cm–2). We detect a weak off-pulse emission, which can be modeled with a softer PL (Γ ≈ 1.7 ± 0.7), that is poorly constrained because of contamination in the EPIC-pn timing mode data. The pulsar's X-ray efficiency in the 0.5-8 keV energy band, , is similar to those of other pulsars. The XMM-Newton observation did not detect extended emission around the pulsar. Our re-analysis of Chandra X-ray Observatory archival data shows a hard, Γ ≈ 0.9 ± 0.5, spectrum and a low efficiency, ηPWN ~ 2 × 10–5(D/10 kpc)2, for the compact pulsar wind nebula, unresolved in the XMM-Newton images.
The Acoustic Influence of Cell Depth on the Rotordynamic Characteristics of Smooth-Rotor/Honeycomb-Stator Annular Gas Seals

A two-control-volume model is employed for honeycomb-stator/smooth-rotor seals, with a conventional control-volume used for the throughflow and a capacitance-accumulator model for the honeycomb cells. The control volume for the honeycomb cells is shown to cause a dramatic reduction in the effective acoustic velocity of the main flow, dropping the lowest acoustic frequency into the frequency range of interest for rotordynamics. In these circumstances, the impedance functions for the seals cannot be modeled with conventional (frequency-independent) stiffness, damping, and mass coefficients. More general transform functions are required to account for the reaction forces, and the transfer functions calculated here are a lead-lag term for the direct force function and a lag term for the cross-coupled function. Experimental measurements verify the magnitude and phase trends of the proposed transfer functions. These first-order functions are simple, compared to transfer functions for magnetic bearings or foundations. For synchronous response due to imbalance, they can be approximated by running-speed-dependent stiffness and damping coefficients in conventional rotordynamics codes. Correct predictions for stability and transient response will require more general algorithms, presumably using a state-space format.
Why do analysts revise their stock recommendations after earnings announcements

Recent research finds that many analyst recommendation revisions take place shortly after earnings announcements. Altinkilic and Hansen (2009) attribute the clustering of recommendations to analysts strategically piggybacking on earnings information to improve the perceived performance of their recommendations. This study proposes an alternative view: I find that analysts issue recommendations when they face greater demand from investors, when the relative supply of information available on earnings announcements is higher and when they detect mispricings. These results are consistent with analysts striving to meet the demands of investors by providing useful recommendations after earnings announcements.
Quantifying the speculative component in the real price of oil: The role of global oil inventories

Abstract One of the central questions of policy interest in recent years has been how many dollars of the inflation-adjusted price of oil must be attributed to speculative demand for oil stocks at each point in time. We develop statistical tools that allow us to address this question, and we use these tools to explore how the use of two alternative proxies for global crude oil inventories affects the empirical evidence for speculation. Notwithstanding some differences, overall these inventory proxies yield similar results. While there is evidence of speculative demand raising the price in mid-2008 by between 5 and 14 dollars, depending on the inventory specification, there is no evidence of speculative demand pressures between early 2003 and early 2008. As a result, current policy efforts aimed at tightening the regulation of oil derivatives markets cannot be expected to lower the real price of oil in the physical market. We also provide evidence that the Libyan crisis in 2011 shifted expectations in oil markets, resulting in a price increase of between 3 and 13 dollars, depending on the inventory specification. With regard to tensions with Iran in 2012, the implied price premium ranges from 0 to 9 dollars.
X-ray populations in galaxies

Abstract High-resolution Chandra observations have allowed the detection of populations of X-ray sources in galaxies of all morphological types. The X-ray Luminosity Functions (XLFs) of these X-ray source populations have been derived and studied to uncover the drivers for the formation and evolution of binaries in different stellar populations and environments. These XLFs also provide a tool for identifying the nature of the X-ray source population, since different XLFs characterize X-ray sources belonging to young and old stellar populations. Similarly, X-ray colors can be used for identifying different types of X-ray sources. Ultra-Luminous X-ray sources (ULXs, L X > 10 39 ergs s −1 ) are found to be associated with star-forming stellar populations. The study of the ULX population of the Antennae galaxies points to compact accreting binaries.
THE FREQUENCY OF ACTIVE AND QUIESCENT GALAXIES WITH COMPANIONS: IMPLICATIONS FOR THE FEEDING OF THE NUCLEUS

We analyze the idea that nuclear activity, either active galactic nuclei (AGNs) or star formation, can be triggered by interactions by studying the percentage of active, H II, and quiescent galaxies with companions. Our sample was selected from the Palomar survey and avoids selection biases faced by previous studies. This sample was split into five different groups, Seyfert galaxies, LINERs, transition galaxies, H II galaxies, and absorption-line galaxies. The comparison between the local galaxy density distributions of the different groups showed that in most cases there is no statistically significant difference among galaxies of different activity types, with the exception that absorption-line galaxies are seen in higher density environments, since most of them are in the Virgo Cluster. The comparison of the percentage of galaxies with nearby companions showed that there is a higher percentage of LINERs, transition galaxies, and absorption-line galaxies with companions than Seyfert and H II galaxies. However, we find that when we consider only galaxies of similar morphological types (elliptical or spiral), there is no difference in the percentage of galaxies with companions among different activity types, indicating that the former result was due to the morphology-density effect. In addition, only small differences are found when we consider galaxies with similar Hα luminosities. The comparison between H II galaxies of different Hα luminosities shows that there is a significantly higher percentage of galaxies with companions among H II galaxies with L(Hα) > 1039 ergs s-1 than among those with L(Hα) ≤ 1039 ergs s-1, indicating that interactions increase the amount of circumnuclear star formation, in agreement with previous results. The fact that we find that galaxies of different activity types have the same percentage of companions suggests that interactions between galaxies is not a necessary condition to trigger the nuclear activity in AGNs. We compare our results with previous ones and discuss their implications.
Gravisensing in flax roots – results from STS-107

Abstract The goal of the experiment “magnetophoretic induction of curvature in roots” (MICRO) on STS-107 was the induction of curvature in roots by high-gradient magnetic fields (HGMF) in microgravity. The scientific objectives included investigating the growth/curvature pattern in response to a HGMF, the determination of amyloplasts as gravisensing/curvature-inducing structures, and a study of the effects of HGMF and microgravity on the plant cytoskeleton. Flax seeds were germinated in orbit in specially designed seed cassettes. The seeds were oriented so that the emerging roots grew away from the cassette. The magnetic system consisted of ferro-magnetic wedges, magnetized by permanent NdFeB magnets (coercivity > 32k Oe). The HGMF that results from the transition from the high magnetic field density at the wedge tips to air repels diamagnetic amyloplasts. As a result of the previously demonstrated internal displacement of the amyloplasts, the roots were expected to curve as if gravistimulated. Despite successful germination (>90%), the growth rate of the seedlings was significantly lower than comparable controls. Despite the slower growth rate, root curvature was enhanced and initiated earlier than in ground controls. The results indicate that microgravity-grown roots exhibit higher sensitivity for the HGMF than ground controls. The enhanced sensitivity of root curvature in microgravity suggests that the root gravisensing system responds to the displacement of amyloplasts. In the absence of gravity, the higher sensitivity might result from intracellular motion, which in microgravity is likely to be stronger than on the ground.
Locating network monitors: Complexity, heuristics, and coverage

There is an increasing interest in passive monitoring of IP flows at multiple locations within an IP network. The objective of such a distributed monitoring system is to sample packets belonging to a large fraction of IP flows in a cost-effective manner by carefully placing monitors and controlling their sampling rates. In this paper, we consider the problem of where to place monitors within the network and how to control their sampling. To address the tradeoff between monitoring cost and monitoring coverage, we propose and study minimum cost and maximum coverage problems under various budget constraints and in the presence of routing changes caused by link failures. We show that all of the problem formulations are NP-hard. We propose greedy heuristics, and show that the heuristics provide solutions quite close to the optimal solutions through experiments using synthetic and real network topologies. In addition, our experiments show that a small number of monitors often suffices to monitor most of the traffic in an entire IP network.
Analysis of calibration errors for both short and long stroke white light experiments

The SIM PlanetQuest mission can provide microarcsecond (μas) accuracy for exoplanet searches and critical astrophysical research. SIM is the only mission which can measure angular wobbles caused by planets for determination of planetary masses. In order to reach μas accuracy the SIM instrument must be able to measure fringe parameters to the accuracy of picometers. It is necessary to investigate calibration techniques and to carefully analyze influences from ghost images in white light fringe measurements. This work will analyze focusing and tilt variations introduced by thermal changes in calibration processes. In particular the accuracy limits are presented for common short- and long-stroke experiments. A new, simple, practical calibration scheme is proposed and analyzed based on the SIM PlanetQuest's Micro-Arcsecond Metrology (MAM) testbed experiments.
New tools for analyzing quark mixing

We present some new mathematical tools which help to derive information about the quark mass matrices directly from experimental data and to elucidate the structure of these mass matrices.
A password extension for improved human factors

Abstract To maximize both the difficulty of guessing passwords and also the ease of remembering passwords, we use a fairly large keyspace (64 bits) and a very long “passphrase” (up to 80 characters). The phrase is hashed into the key, which is then stored in encrypted form. The hashing necessarily includes one-way encryption. Since the phrase is long, one would expect a large keyspace for the actual phrase as well as for the hashed phrase. Since the phrase is meaningful to the owner it should be easier to remember.
Dynamics of interacting clusters and dielectric response in relaxor ferroelectrics

The dielectric response in relaxor ferroelectrics is analyzed in the framework of a model for the polarization dynamics in the presence of polar clusters. We associate the origin of polar clusters with atoms displaced from their centrosymmetrical positions even above ${T}_{c}.$ Their collective hopping in multiwell potentials induced by disorder is analogous with the situation in glasses. The theory explicitly takes into account the distribution of cluster reorientation frequencies and the effect of cluster-cluster interactions in highly polarizable crystals, which we describe in terms of the local field distribution function. The dielectric constant is obtained from an integral master equation for the polarization dynamics in the presence of a time-dependent electric field. The theory is applied to the analysis of the shape of the frequency-dependent permittivity in the typical relaxor ferroelectric PST as a function of temperature. Comparison of theory with experiment shows that in contrast to earlier assumptions, the observed Vogel-Fulcher dependence of the permittivity maximum is a consequence of the Vogel-Fulcher temperature dependence of the cluster-reorientation frequency.
Equivalent string networks and uniqueness of BPS states

Abstract We analyze string networks in 7-brane configurations in IIB string theory. We introduce a complex parameter M characterizing equivalence classes of networks on a fixed 7-brane background and specifying the BPS mass of the network as MBPS = | M |. We show that M can be calculated without knowing the particular representative of the BPS state. Based on a detailed examination of backgrounds with three and four 7-branes we argue that equivalent networks may not be simultaneously BPS, an essential requirement of consistency.
X-Ray Emission from Rotating Elliptical Galaxies

The slow inward flow of the hot gas in elliptical galaxy cooling flows is nearly impossible to detect directly because of instrumental limitations. However, in rotating galaxies, if the inflowing gas conserves angular momentum, it will eventually form a disk. The X-ray signature of this phenomenon is a flattening of the X-ray isophotes in the inner 1-10 kpc region. This effect is observable, so we have searched for it in X-ray observations of six rotating and nonrotating early-type galaxies, obtained mainly with the ROSAT PSPC and HRI imagers. The ellipticities of the X-ray emission never increase toward the central region, nor are the X-ray ellipticities significantly greater than the ellipticities for the optical stellar emission. Central ellipticities in excess of 0.5 were expected in rotating ellipticals, whereas values of 0-0.2 are measured. The failure to detect the expected signature requires a modification to the standard cooling-flow picture, possibly including partial galactic winds, rapid mass dropout, or turbulent redistribution of angular momentum.
The discovery of 50 minute periodic absorption events from 4u1915-05

The steady flux from 4U1916-05 which undergoes periodic absorption dips every 50 minutes was demonstrated. This period represents the underlying orbital period of the system. It is suggested that variations in the depth and duration of these events are caused by a bulge in the edge of the accretion disk, at the point where the gas stream impacts the disk. The mass losing star in this system is probably a low mass white dwarf. The spectrum of the dips indicates that the metallicity of the absorbing material is at least a factor 17 below solar values.
Which school attributes matter?: The influence of school district performance and demographic composition on property values

Abstract Increasing levels of segregation in American schools raises the question: do home buyers pay for test scores or demographic composition? This paper uses Connecticut panel data spanning eleven years from 1994 to 2004 to ascertain the relationship between property values and school district attributes, such as student test scores and the racial and ethnic composition of the student body. Town and census tract fixed effects are included to control for neighborhood unobservables. The effect of changes in school district attributes is also examined over a decade long time frame in order to focus on the effect of long-run changes, which are more likely to be capitalized into prices. The study finds strong evidence that increases in percent Hispanic have a negative effect on housing prices in Connecticut, but mixed evidence concerning the impact of test scores on property values. Student test scores also appear to have increased in importance for explaining housing prices in recent years, while the importance of percent Hispanic has declined. Finally, the study finds that estimates of property tax capitalization increase substantially when the analysis focuses on long run changes.
On spun-normal and twisted squares surfaces

Given a 3 manifold M with torus boundary and an ideal triangulation, Yoshida and Tillmann give different methods to construct surfaces embedded in M from ideal points of the deformation variety. Yoshida builds a surface from twisted squares, whereas Tillmann produces a spun-normal surface. We investigate the relation between the generated surfaces and extend a result of Tillmann's (that if the ideal point of the deformation variety corresponds to an ideal point of the character variety, then the generated spun-normal surface is detected by the character variety) to the generated twisted squares surfaces.
DOES IT PAY TO GET AN A? SCHOOL RESOURCE ALLOCATIONS IN RESPONSE TO ACCOUNTABILITY RATINGS

Abstract This paper examines public school district budgetary responses to school accountability ratings. We identify school district budgetary changes through a “rating shock” due to a major change in school accountability systems in Texas. Texas implemented a new accountability system and new exam, and allowed schools a “gap” year to adjust to the new test. Using the new Texas exam as an exogenous change, we find a 1.5% increase in instructional budgets, mainly for teachers, as a response to a drop in rating. This increase is found to disappear within 3 years, suggesting temporary budget support to “learn” the new system but no long run institutional change.
DRAFTS: A Deep, Rapid Archival Flare Transient Search in the Galactic Bulge

We utilize the Sagittarius Window Eclipsing Extrasolar Planet Search Hubble Space Telescope/Advanced Camera for Surveys data set for a Deep Rapid Archival Flare Transient Search to constrain the flare rate toward the older stellar population in the Galactic bulge. During seven days of monitoring 229,293 stars brighter than V = 29.5, we find evidence for flaring activity in 105 stars between V = 20 and V = 28. We divided the sample into non-variable stars and variable stars whose light curves contain large-scale variability. The flare rate on variable stars is ~700 times that of non-variable stars, with a significant correlation between the amount of underlying stellar variability and peak flare amplitude. The flare energy loss rates are generally higher than those of nearby well-studied single dMe flare stars. The distribution of proper motions is consistent with the flaring stars being at the distance and age of the Galactic bulge. If they are single dwarfs, then they span a range of ≈1.0-0.25 M ☉. A majority of the flaring stars exhibit periodic photometric modulations with P < 3 days. If these are tidally locked magnetically active binary systems, then their fraction in the bulge is enhanced by a factor of ~20 compared to the local value. These stars may be useful for placing constraints on the angular momentum evolution of cool close binary stars. Our results expand the type of stars studied for flares in the optical band, and suggest that future sensitive optical time-domain studies will have to contend with a larger sample of flaring stars than the M dwarf flare stars usually considered.
Superconformal change of variables for N=1 Neveu–Schwarz vertex operator superalgebras

Abstract Superconformal change of variables formulas for N =1 Neveu–Schwarz vertex operator superalgebras are presented for general invertible superconformal changes of variables. Using the underlying worldsheet supergeometry of propagating superstrings, geometric proofs of the change of variables formulas are given for the case of convergent superconformal changes of variables. More general formal algebraic proofs of the change of variables formulas in the case of formal superconformal changes of variables are then given. Finally, isomorphic families of N =1 NS-VOSAs are derived from the superconformal change of variables formulas.
A Cooperative Publishing Model for Sustainable Scholarship

Organizing scholarly publishing as a cooperative business has the promise of making journals more affordable and scholarly publishing more sustainable. The authors describe the development of the modern cooperative from its beginnings in England during the Industrial Revolution and highlight the great extent and diversity of business worldwide that is currently done cooperatively. Some of the current initiatives in scholarly publishing (SPARC, PLoS, German Academic Publishing, etc.) are analysed in light of cooperative business principles, and it is shown that, while these models often partially utilize cooperative business practices, none of them has adopted the cooperative model in totality.
From factorizations of noncommutative polynomials to combinatorial topology

This is an extended version of a talk given by the author at the conference “Algebra and Topology in Interaction” on the occasion of the 70th Anniversary of D.B. Fuchs at UC Davis in September 2009. It is a brief survey of an area originated around 1995 by I. Gelfand and the speaker.
Establishing online trust through a community responsibility system

Abstract Much of the research on trust building in electronic commerce takes a descriptive approach. The question of what social structures are more appropriate to promote trust in the online world has not been extensively studied. We analyze in this paper, using a prescriptive approach, how a certain social structure—a community responsibility system, supported by present technology, can be set up. We use game theoretic tools to prove that under the community responsibility system for trust building, online transactions that are impersonal can be supported and can preserve at the same time anonymity to a large extent.
Privileged Chiral Catalysts

One of the most active current areas of chemical research is centered on how to synthesize handed (chiral) compounds in a selective manner, rather than as mixtures of mirror-image forms (enantiomers) with different three-dimensional structures (stereochemistries). Nature points the way in this endeavor: different enantiomers of a given biomolecule can exhibit dramatically different biological activities, and enzymes have therefore evolved to catalyze reactions with exquisite selectivity for the formation of one enantiomeric form over the other. Drawing inspiration from these natural catalysts, chemists have developed a variety of synthetic small-molecule catalysts that can achieve levels of selectivity approaching, and in some cases matching, those observed in enzymatic reactions.
HYGROSCOPIC MOISTURE TRANSFER IN FIBROUS MATERIAL

In order to investigate hygroscopic moisture transfer in fibrous material, experiments were conducted to measure the mass flux and moisture distribution through a sample of glass fiberboard (138kg/m3). The samples ranging in thickness from 0.0388 to 0.053 m were exposed isothermally to relative humidity gradients ranging from 35 to 100%. The equilibrium moisture content was used as the driving force for transfer. The mass conductivity was calculated from the flux and distribution data and found to vary from 0.199 to 0.348 g/cm-hr (5.53 × 10−6 to 9.67 × 10−6kg/m-s) increasing slightly with increasing relative humidity difference. The data was also used to calculate the mass diffusivity and permeability of the fiberglass. The results from this study were combined with data from earlier work on thermal mass transfer to determine the thermal mass conductivity of fiberboard and to provide an overall description of nonisothermal mass transfer. A better understanding of overall hygroscopic moisture transfer is i...
A Metamodel Specification for a Tomato Processing Plant

This paper reports on the specification of a tomato processing plant cost-function using the Schruben-Cogliano (S-C) experimental procedure for response surface identification. The method is applied to a simulation model of a tomato processing plant in order to generate a cost-function metamodel that can be used to derive conditional factor-demand equations. The results suggest that the S-C methodology provides a means of deriving conditional factor-demand equations which reduces cost-function specification error.
Field Evaluation of Catalytic Deoxygenation Process for Oxygen Scavenging in Oilfield Waters

Etude technico-economique de la mise en œuvre du procede Cadeox de desoxygenation catalytique des eaux d'injection dans le champ de petrole San Mignelito, a Ventura en Californie. Le catalyseur est une resine echangeuse d'anion recouverte de palladium. L'oxygene dissous dans l'eau est reduit catalytiquement et forme de l'eau par reaction avec de l'hydrogene
Mesoscale connectivity through a natural levee

Abstract. Natural levees are potentially locally important zones of lateral seepage between stream channels and floodplain backswamps, because their relatively coarser soils provide pathways of high hydraulic conductivity in an otherwise low conductivity system. Therefore, understanding the rates and mechanisms of subsurface exchange of water and solutes through natural levees may be necessary for understanding biogeochemical cycling in floodplains. We measured imposed hydraulic gradients and solute tracers in 19 shallow monitoring wells within a 580 m3 volume of natural levee in the Atchafalaya Basin, Louisiana. We modeled residence time distributions of pressure and tracers using a simple linear system to quantify spatially variable transport velocities and infer dominant flow mechanisms at a mesoscale. The spatial mean velocity of pressure transport was faster than the mean velocity of tracer transport by two orders of magnitude (1.7 × 10−2 and 4.6 × 10−4 m s−1, respectively), and the variance of pressure velocities was less than the variance of tracer velocities by seven orders of magnitude (1.4 × 104 min2 and 7.9 × 1011 min2, respectively). Higher spatial variability of tracer velocities compared to pressure velocities indicates different functioning mechanisms of mass versus energy transport and suggests preferential flow. Effective hydraulic conductivities, which ranged in magnitude from 10−1 to 103 m d−1, were higher than would be predicted by soil texture. We conclude that, in this fine-grained system, preferential flow paths control water and solute exchange through natural levees. These findings are important for future studies of water and solute cycling in riverine wetlands, and rates of exchange may be particularly useful for modeling water and nutrient budgets in similar systems.
Structure-borne noise control for propeller aircraft

A laboratory test apparatus was developed which would allow the study and development of propeller wake/vortex-induced structure-borne interior noise control measures. Various methods of wing structural modification, including blocking masses, surface damping treatments, and tuned mechanical absorbers, were evaluated relative to reduced interior noise levels. Inboard wing fuel was found to act as an effective blocking mass. Wing panel add-on damping treatment in the form of a single, constrained layer was not an effective control measure, except in the area of the propeller wake. However, highly damped, tuned mechanical absorbers were found to be the most efficient structure-borne noise (SBN) control measure.
A Complete Characterization of Efficient Liability Rules: Comment

In a recent article, Jain and Singh (2002) prove that a condition they call negligence liability is necessary and sufficient for any liability rule to be efficient. In this note I criticize their result on two accounts: First, their result crucially depends on implicit restrictions they impose on the liability assignment function. If we drop the assumption that the liability apportionment between two non-negligent parties is constant for all combinations of non-negligent care levels, the equivalence between the condition of negligence liability and the efficiency of liability rules breaks down. Second, their attempt to drop the assumption of uniqueness for the social optimum improves the generality of the model at a substantial cost, since it must be accompanied by a new assumption that is possibly even more unrealistic. The importance of the uniqueness assumption is shown in a simple discrete care model, in which comparative negligence may lead to an inefficient outcome when the existence of two social optima leads us to interpret due care as a varying standard based on the other party’s actual choice.
Orbit Trim Strategies for the 1975 Mars Viking Mission

Propulsive maneuver strategies have been developed for the Mars orbital phases of the Viking mission, including the activities before and after lander deployment. These strategies have been formulated as fixed sequences of orbit parameter-correction maneuvers which will be performed on specified spacecraft revolutions. Certain adaptive features are also available to ensure efficient use of propellants. Numerical simulations demonstrate that it is possible (to within a very high probability) to satisfy mission requirements on orbital navigation, using these strategies and Viking technology. HE United States will send two unmanned spacecraft to Mars during the 1975 launch opportunity. Each of these spacecraft will orbit Mars and deploy a soft-lander to the surface of the planet as part of the Viking Project. These objectives place a number of interesting and stringent requirements on the control of the satellite orbit to obtain near periapsis reconnaissance of the landing site and to prepare for lander release. As a result, the preflight navigation analyses and maneuver strategy development have been considerably increased in scope and complexity over previous missions. Reference 1 describes the Viking mission objectives and overall navigation profile from trans-Mars injection through the postlanding station-keeping phase. During the Mars orbit trim (MOT) phase of each flight, a sequence of orbit trim spacecraft propulsive maneuvers is performed to remove the effects of orbit determination and maneuver execution errors, plus any intentional biases, remaining after earlier maneuvers in the flight. The sequence of trim maneuvers is performed according to a predetermined strategy designed to achieve the mission objectives. This paper describes the maneuver objectives and the resulting strategies for the Mars orbital phases of the Viking mission, including the activities before and after lander deployment. The prelanding activities are treated in Sec. II-IV, with the consideration of postlanding activities being reserved for Sec. V. Numerical results are included in Sec. IV and V to demonstrate that the strategies satisfy all mission requirements which have been identified The preflight navigation analyses for Viking have included the analyses of the two typical missions defined in Table 1. The . typical candidate for the first spacecraft is referred to in this paper as Mission 1, while the candidate for the second spacecraft is called Mission 2. These example missions are considered in this paper to clarify techniques and to provide realistic numerical results. They are not intended to contribute a parametric analysis of all possible Viking missions. Table 1 Selected parameters for Missions 1 and 2 Parameter Mission 1 Mission 2
Synthesis and structure of the first indium–copper cluster, [Cu6In3(SEt)16]– and its possible relevance to CuInS2

The cluster (Ph4P)[Cu6In3(SEt)16] has been prepared by the reaction of [Cu(CH3CN)4]PF6 with (Ph4P)[In(SEt)4] and its crystal structure shows an adamantoid framework.
A vorton gun

Abstract In about half of all near-cusp events in superconducting cosmic strings with chiral currents (and probably with general currents as well), the string intersects itself near the cusp. Intercommutation causes the conversion of the string near the cusp into a vorton (in the chiral case) with very high Lorentz boost. We demonstrate how to analyze the cusp shape in a Lorentz frame that makes the motion simple, by the use of a 5-dimensional procedure, and analyze the resulting production of vortons.
Does the topology of space fluctuate

Evidence is presented that the singularities induced in causal Lorentzian spacetimes by changes in 3-space topology give rise to infinite particle and energy production under reasonable laws of quantum field propagation. In the case of the gravitational field, if 3-space is compact the total energy must vanish. A topological transition therefore induces a violent collapse that effectively aborts the transition, since the collapse mode is the only mode carrying the negative energy needed to compensate the associated infinite energy production. The existence of the Hamiltonian constraint of general relativity suggests that topological stability is a local property of the quantum theory that is maintained even when 3-space is noncompact.
Correlators of the global symmetry currents of 4D and 6D superconformal theories

We study the two-point correlators of the currents of the E8 global symmetry in the N = (1, 0) superconformal six-dimensional theory as well as in the 4D superconformal theories upon toroidal compactification. From the high-energy behavior of the correlator we deduce that in 4D 10 copies of the superconformal theory with E8 global symmetry can be coupled to an N = 2 E8 gauge theory. We present three alternative derivations for the expression for the correlators. One from field theory, one from M-theory and one from F-theory.
Asymptotic analysis of the Bell polynomials by the ray method

We analyze the Bell polynomials B"n(x) asymptotically as n->~. We obtain asymptotic approximations from the differential-difference equation which they satisfy, using a discrete version of the ray method. We give some examples showing the accuracy of our formulas.
Synthesis and competency of a novel dicationic phase-transfer catalyst

Abstract Synthesis and characterization of a novel phase-transfer catalyst, 6,6′ di(triethylammoniummethyl)-2,2′-dihexyloxybi-1,1′-naphthalene, are reported. Preliminary catalytic studies on the alkylation of a glycine derivative show the catalyst to be an effective phase-transfer catalyst but with no enantioselectivity.
Culture and the ownership concentration of public corporations around the world

Abstract As a country's attitude toward egalitarianism increases, which means a societal preference for the equal as opposed to hierarchical treatment of individuals, the ownership of the public corporations in the country becomes more concentrated. This finding is robust to a wide range of specifications and methodologies. Once egalitarianism is accounted for, there is no evidence that other cultural attitudes, including trust and religion, or legal protections for public market investors, including those laws that figure prominently in the literature, are related to ownership concentration. One explanation for the robust association between egalitarianism and ownership concentration is that large shareholders are valuable when employees have strong legal rights.
Some candidate atoms and ions for frequency standards research using laser radiative cooling techniques

Abstract The rapid progress in laser atomic cooling ideas and also in laser spectral coverage and frequency stabilization make it appropriate to reexamine the periodic table for atoms and ions that may be of special interest for radiatively-cooled frequency standards research. We discuss Hg + , Pb + , Ba + , neutral alkalis, Mg, Ca, and Ag. Optical two-photon and weak single-photon transitions are represented, along with microwave hfs and fs transitions.
Stress Relaxation Modulus of a Commercial Glass

The stress relaxation modulus in compression of a container glass was investigated over a wide range of strain, time, modulus, and temperature. The glass is a linear viscoelastic liquid up to 2% strain, and the modulus is a smooth function of time, with no pseudorubbery plateau apparent down to a modulus of 10° dynes/cm2. The data cover 4 decades in time and a range of almost 100°C above the glass transition, T0=536°C. Within experimental error, changes in temperature simply shift the modulus-vs-time curve along the time axis without altering its shape. This behavior implies that the same mechanism controls both the bulk and shear spectra. The shift factors fit the WLF equation well with values for the parameters c1 and c2 of 16.7±0.2 and 345±5°C, respectively. Data from the literature for silicate glasses agree with these parameters.
Comparisons of horizontal and vertical velocity spectra in the mesosphere, stratosphere and troposphere: Observations and theory

Simultaneous observations of oblique and vertical velocities using the Poker Flat MST Radar are analyzed to determine spectra of horizontal and vertical motions in the upper troposphere, lower stratosphere and mesopause region. These spectra are compared with predictions from an internal wave spectral model and significant discrepancies are found. These discrepancies raise important questions regarding the interpretation of the observed spectra solely in terms of internal waves.
N-Benzoyl-4-(dimethylamino)pyridinium Chloride: Isolation and Use for the Direct Benzoylation of Alcohols

Abstract A simple method for the formation and isolation of N-benzoyl-4-(dimethylamino)pyridinium chloride is described. This reagent can be employed directly for the benzoylation of secondary and tertiary alcohols. Mailing address: Room 327C, The Faculty Bldg.; 847 Monroe St.; Memphis, TN 38163. E-mail: mwolfe@utmeml.utmem.edu.
Improved Statistical Processing for Common-Conversion-Point Stacked Receiver Functions

The interpretation of teleseismic receiver functions (RFs) is typically limited by poor constraints on the uncertainty of amplitudes of converted phases. In continental regions these problems are overcome by stacking large amounts of data. In oceanic regions, however, data quality is notoriously noisy and the number of events are often limited by significantly shorter station deployment times. Estimates of RF pulse amplitude uncertainty are, therefore, necessary to allow an analyst to differentiate between real structure in the Earth and random correlations in ambient noise. Here we combine a common-conversion-point stacking technique with multiple-taper correlation RF estimates, which allow frequency-domain weighting. We then compute jackknife statistics to estimate local uncertainties in RF amplitude. We apply this technique to a continental station in Arabia (RAYN) and to the ocean island station at Raratonga, Cook Islands (RAR) in order to compare our method to results obtained via other techniques. The structure we recover matches previous crustal studies at both stations and provides new interpretations of conversions in the upper mantle. At single stations this technique works well to resolve crust and mantle structure up to a depth of 100 km. Geographical dispersion of ray paths at greater depths decreases the number of events per bin and, therefore, increases the uncertainty in converted amplitude. The ability to stack crossing ray paths implies that this method will be well suited to the analysis of data from seismic arrays.
Oxidation of Sulfides with N‐Bromosuccinimide in the Presence of Hydrated Silica Gel

Abstract An efficient and highly selective procedure for oxidation of sulfides to sulfoxides with N‐bromosuccinimide (NBS) in the presence of hydrated silica gel has been developed. Hydrated silica gel supplies the water necessary for decomposition of the intermediate bromosulfonium salt to the product, allowing the reaction to employ a nonaqueous media. Also, this procedure has increased the scope of the reaction by oxidizing a wider variety of sulfides, which was not possible until now.
A simple synthetic process for the elaboration of oligoprenols by stereospecific coupling of di-, tri-, or oligoisoprenoid units

Abstract An effective method of allyl-allyl coupling which is position and stereospecific leads in a simple way to oligoprenols from E-allylic halides.
Enforcement of pollution regulations in a declining industry

Abstract A regulatory agency enforcing compliance in a declining industry might recognize that certain plants would close rather than comply, imposing large costs on the local community. Data on EPA enforcement activity in the U.S. steel industry are examined for evidence of this with a two-equation model linking EPA enforcement decisions and firms' plant-closing decisions. The results indicate that the EPA directed fewer enforcement actions toward plants with a high predicted probability of closing and plants that were major employers in their community; also, plants predicted to face relatively heavy enforcement were more likely to close.
Slepton discovery in electroweak cascade decay

The LHC studies on the MSSM slepton sector have mostly been focused on direct slepton Drell-Yan pair production. In this paper, we analyze the case when the sleptons are lighter than heavy neutralinos and can appear in the on-shell decay of neutralino states. In particular, we have studied the $ \chi_1^{\pm }\chi_2^0 $ associated production, with the consequent decays of $ \chi_1^{\pm } \to {\nu_{\ell }}\ell \chi_1^0 $ and $ \chi_2^0 \to \ell \ell \chi_1^0 $ via on-shell sleptons. The invariant mass of the lepton pairs, m ll , from the neutralino decay has a distinctive triangle shape with a sharp kinematic cutoff. We discuss the utilization of this triangle shape in m ll distribution to identify the slepton signal. We studied the trilepton plus missing E T signal and obtained the effective cross section, σ × BR × acceptance, that is needed for a 5σ discovery as a function of the cutoff mass for the LHC with center of mass energy 14 TeV and 100 fb−1 integrated luminosity. Our results are model independent such that they could be applied to other models with similar decay topology. When applied to the MSSM under simple assumptions, it is found that with 100 fb−1 integrated luminosity, a discovery reach in the left-handed slepton mass of about 600 GeV could be reached, which extends far beyond the slepton mass reach in the usual Drell-Yan studies.