cssi/SciSciGPT-SciSciNet huggingface dataset:
A Batalin-Vilkovisky algebra structure on the Hochschild cohomology of truncated polynomials.

Abstract We calculate the Batalin–Vilkovisky, and the induced Gerstenhaber structures of the Hochschild cohomology of the singular R -cochain complex of n -dimensional K -projective spaces, where K = C , H and R = Z and any field. In the special case that K = C , n = 1 and R = Z , we show that this structure cannot be identified with the BV-structure of the integral loop homology of the 2-dimensional sphere computed by L. Menichi, but their induced Gerstenhaber structures can still be identified. Combined with the work of Y. Felix and J. Thomas, the main result of the present paper calculates the BV-structure of the rational loop homology of projective spaces.
Synthesis and X-ray Crystal Structures of Two 14-vertex Di-iron Tetracarbon Metallocarbaboranes

The reaction of Me4C4B8H8 with NaC10H8, NaC5H5, and FeCl2 produces at least four isomers of [(η5-C5H5)2Fe2Me4 C4B8H8], two of which have been structurally characterized from X-ray crystallographic studies and form 14-vertex polyhedra; neither compound has the closo-structure predicted from electron-counting rules, containing instead a 5-membered and a 4-membered open face respectively.
Special-purpose hardware for text searching: past experience, future potential

Abstract The partitioned finite state automaton (PFSA) was proposed ten years ago as a new way of implementing a hardware-based pattern matcher for text information retrieval systems. The pattern matcher was part of a special-purpose search processor to be attached to each disk of a large information retrieval system. Since then, there have been dramatic changes in microprocessor, memory, and disk technologies. After an overview of the experiences in implementing and evaluating the PFSA searcher, the applicability of special-purpose hardware for text searching in the future is discussed. The use of a surrogate, such as a partially inverted file, in conjunction with the search hardware, is examined, particularly regarding the overhead of the surrogate and any changes to the operation and performance of the search system. Searching using the higher speed RISC microprocessors available today as an alternative to a custom searcher is presented, and a hardware-augmented approach is proposed.
The topology of the space of rational curves on a toric variety

Let $X$ be a compact toric variety. Let $Hol$ denote the space of based holomorphic maps from $CP^1$ to $X$ which lie in a fixed homotopy class. Let $Map$ denote the corresponding space of continuous maps. We show that $Hol$ has the same homotopy groups as $Map$ up to some (computable) dimension. The proof uses a description of $Hol$ as a space of configurations of labelled points, where the labels lie in a partial monoid determined by the fan of $X$.
Measuring External Shocks to the City Economy: An Index of Export Prices and Terms of Trade

This paper details the construction of an index of export goods prices (the Export Price Index or EPI) for a panel of 196 metropolitan areas from 1977 to 1992. The EPI is an indicator of external demand shocks to the city economy which does not suffer from the causal ambiguity of the endogenous indicators such as income, employment or output. The creation of an index of aggregate export prices, the EPI, for the panel of areas provides both academicians and policy analysts with a new exogenous indicator that identifies demand price innovations and the terms of trade shocks to cities.
Gravitationally distorted P Cygni profiles from outflows near compact objects

We consider resonant absorption in a spectral line in the outflowing plasma within several tens of Schwarzschild radii from a compact object. We take into account both Doppler and gravitational shifting effects and reformulate the theory of P Cygni profiles in these new circumstances. It is found that a spectral line may have multiple absorption and emission components depending on how far the region of interaction is from the compact object and what the distribution of velocity and opacity is. Profiles of spectral lines produced near a neutron star or a black hole can be strongly distorted by Doppler blue- or redshifting and gravitational redshifting. These profiles may have both red- and blueshifted absorption troughs. The result should be contrasted with classical P Cygni profiles, which consist of redshifted emission and blueshifted absorption features. We suggest that this property of line profiles to have complicated narrow absorption and emission components in the presence of strong gravity may help researchers to study spectroscopically the innermost parts of an outflow.
A potential-function reduction algorithm for solving a linear program directly from an infeasible “warm start”

This paper develops an algorithm for solving a standard-form linear program directly from an infeasible “warm start”, i.e., directly from a given infeasible solution $$\hat x$$ that satisfies $$A\hat x = b$$ but $$\hat x \ngeqslant 0$$ . The algorithm is a potential function reduction algorithm, but the potential function is somewhat different than other interior-point method potential functions, and is given by $$F(x,B) = q\ln (c^T x - B) - \sum\limits_{j = 1}^n {\ln (x_j + h_j (c^T x - B))}$$ where $$q = n + \sqrt n$$ is a given constant,h is a given strictly positive shift vector used to shift the nonnegativity constaints, andB is a lower bound on the optimal value of the linear program. The duality gapc T x − B is used both in the leading term as well as in the barrier term to help shift the nonnegativity constraints. The algorithm is shown under suitable conditions to achieve a constant decrease in the potential function and so achieves a constant decrease in the duality gap (and hence also in the infeasibility) in O(n) iterations. Under more restrictive assumptions regarding the dual feasible region, this algorithm is modified by the addition of a dual barrier term, and will achieve a constant decrease in the duality gap (and in the infeasibility) in $$O(\sqrt n )$$ iterations.
Synchronization and computing capabilities of linear asynchronous structures

A model is defined in which questions concerning delay bounded asynchronous parallel systems may be investigated. It is shown that synchronization problems, similar to the “firing squad synchronization problem”, cannot be solved by delay bounded asynchronous systems. Three conditions called persistence, determinacy, and single change are introduced. These conditions are shown to be sufficient to guarantee that a synchronous execution policy can be relaxed to an asynchronous execution policy with no change to the result of the computation. This is a Church-Rosser type theorem, but in addition, the asynchronous execution time is shown to be only (D+1) times the synchronous execution time where D is the delay bound. Finally, a wide class of recognition problems is identified which can be solved by linear asynchronous structures.
The Separation of Real Estate Operations By Spin‐Off

In this paper, we consider spin-offs as a vehicle to separate real estate operations from other real estate and/or non-real estate operations. For a sample of 33 such spin-offs announced and completed between 1962 and 1982, we document significantly positive abnormal returns around spin-off announcements. Using the standard event-time methodology, we find average excess returns of 5.7% in the two-day interval surrounding the first Wall Street Journal report of a pending spin-off. While the gains associated with spin-offs by real estate firms are positive on average, they are small in comparison to the 9.1% two-day announcement period abnormal returns surrounding proposals by non-real estate firms to divest real estate operations.
Grope cobordism of classical knots

Motivatedby the lower central series of a group, we d e/ne the notion of a grope cobordism between two knots in a 3-manifold. Just like an iterated group commutator, each grope cobordism has a type that can be d escribedby a rootedunitrivalent tree. By /ltering these trees in d i2erent ways, we show how the Goussarov– Habiro approach to /nite type invariants of knots is closely relatedto our notion of grope cobord ism. Thus our results can be viewedas a geometric interpretation of /nite type invariants. The derived commutator series of a group also has a three-dimensional analogy, namely knots modulo symmetric grope cobord ism. On one handthis theory maps onto the usual Vassiliev theory andon the other handit maps onto the Cochran–Orr–Teichner /ltration of the knot concord ance group, via symmetric grope cobordism in 4-space. In particular, the graded theory contains information on /nite type invariants (with degree h terms mapping to Vassiliev degree 2 h ), Blanch/eldforms or S-equivalence at h = 2, Casson–Gordon
Current Status of Research on Pelvic Muscle Strengthening Techniques

Abstract In the past 15 years, research on the effect of pelvic muscle exercise on urinary stress incontinence has contributed substantially to the understanding of the function of the pelvic muscles and the role of pelvic muscle exercise in management of stress urinary incontinence. This literature review addresses pelvic muscle function, pelvic muscle exercise, pelvic muscle exercise fraining protocols and training aids, changes that result from pelvic muscle exercise, and long-term outcomes of pelvic muscle exercise. Emphasis is placed on results or research that may be used by the clinician with women who experience stress urinary incontinence.
Total Synthesis of Coriandrin

Coriandrin, an antiviral agent, has been synthesized in nine steps from diketone 3. The key steps in the synthesis include an efficient aromatization reaction using N-bromosuccinimide and a palladium-mediated coupling of a benzylic bromide with a vinyl stannane
Superplastic Alumina at Temperatures below 1300°C Using Charge-Compensating Dopants

To achieve low-temperature superplasticity in alumina, we have introduced charge-compensating dopants, Ti4+ and Mn2+, which jointly have a high solubility and significantly enhance the diffusion and deformation processes during sintering and forming. Zirconia as a second-phase pinning agent has also been incorporated to impart microstructural stability against static and dynamic grain growth. The superplastic alumina obtained can be shape-formed under biaxial tension to 100% engineering strain at temperatures below 1300°C. Deformation characteristics of this alumina at temperatures from 1200° to 1400°C and at strain rates from 4 × 10-6 to 3 × 10-3/s are described. The origin of enhanced kinetics is attributed to the formation and dissociation of dopant-defect complexes.
Abundance profiles in cooling-core clusters: a fossil record of past AGN-driven convection?

Central peaks in the iron abundance of intracluster plasma are a common feature of cooling-core galaxy clusters. Although they are centrally localized, these abundance peaks have a broader profile than the stars of the brightest cluster galaxy (BCG) that produce the excess iron, indicating that metal-enriched plasma is transported out of the BCG by some process such as turbulent diffusion. The AGN-driven convection model of Chandran & Rasera predicts the turbulent velocity profile in a steady state cluster in which radiative cooling is balanced by heating from AGN-driven convection and thermal conduction. We use the velocity profiles from this model as input into an advection/diffusion model for the transport of metals in the intracluster medium. We compare the results of our model to XMM-Newton and Chandra observations of eight clusters. Assuming a constant turbulence level over a cluster's lifetime equal to the present value, the turbulent velocities in the model can explain the observed abundance profiles in only five of the eight clusters. However, we go on to develop an analytic fit of the turbulent velocity profile as a function of the AGN power. We then deduce for each cluster the average AGN power (during the past ~10 Gyr) required to match the abundance profiles. The required average values are between 1043 and 2 × 1044 erg s−1, while the present AGN powers span a much larger range. Our results suggest that AGN-driven convection can account for the observed abundance profiles if the AGN power varies in time with average values in the above-quoted range.
Testing cosmological supersymmetry breaking

Abstract Banks has proposed a relation between the scale of supersymmetry breaking and the cosmological constant in de Sitter space. His proposal has a natural extension to a general FRW cosmology, in which the supersymmetry breaking scale is related to the Hubble parameter. We study one consequence of such a relation, namely that coupling constants change as the universe evolves. We find that the most straightforward extension of Banks' proposal is disfavored by experimental bounds on variation of the fine structure constant.
A guide for writing better technical papers

In A Guide for Writing Better Technical Papers, Craig Harkins and Daniel Plung show admirable concern with all aspects of the writing process through their editorial comments and their selection of articles. Unfortunately for the less dedicated writer, the text mixes theory and practice unevenly. And the editors' concern with publication detracts somewhat from the importance of day-to-day writing tasks of the technical writer-communication tasks as important as the finished technical article. Let us consider each of the five sections they include in the text: “Getting Started,” “The Rhetoric of Papers and Articles,” “Tricks of the Trade,” “Some Research Results,” and “Following Through.”
Vertex and edge expansion properties for rapid mixing

We show a strict hierarchy among various edge and vertex expansion properties of Markov chains. This gives easy proofs of a range of bounds, both classical and new, on chi-square distance, spectral gap and mixing time. The 2-gradient is then used to give an isoperimetric proof that a random walk on the grid [k]n mixes in time Oa(k2n). © 2004 Wiley Periodicals, Inc. Random Struct. Alg., 2005
Multifocal atrophic gastritis and gastric carcinoma

Gastric carcinoma is a worldwide disease with widely variable incidence in different geographic areas. In contrast to an overall reduction in incidence in the United States and other industrialized countries, gastric cancer remains the second most common cancer in the world. It continues to be a serious problem in developing countries, and even within specific groups within the United States. In these high-risk populations, multifocal atrophic gastritis (MAG) appears to be the precursor lesion. This article discusses appropriate screening and preventive measures and the identification of co-factors that might interact with H pylori infection to increase gastric cancer risk. To make an impact on gastric cancer incidence and mortality, serious consideration should be given to early H pylori eradication in high-risk groups, and endoscopic surveillance according to the updated Sydney system in some patients; dysplastic lesions should be removed without delay. Studies currently in progress may tell us whether H pylori eradication can prevent later development of gastric carcinoma and thus eliminate a major cause of mortality worldwide.
High angle-of-attack calculations of the subsonic vortex flow on slender bodies

A nonlinear vortex-lattice method is utilized for the calculation of separated vortex flows over slender bodies at high incidence. Symmetric and asymmetric vortex flow cases are calculated showing good agreement with recently obtained experimental data for an ogive-cyclinder body at high Reynolds numbers. The only input needed for these calculations is the positions of the separation lines on the body. Studies of some of the numerical aspects of this method are described and conclusions are implemented to improve the calculations.
Decomposition of quantum gates

A recurrence scheme is presented to decompose an n-qubit unitary gate to the product of no more than N(N - 1)/2 single qubit gates with small number of controls, where N = 2n. Detailed description of the recurrence steps and formulas for the number of k-controlled single qubit gates in the decomposition are given. Comparison of the result to a previous scheme is presented, and future research directions are discussed.
Mechanisms in Essential Hypertension

1. There are two basic interdependent mechanisms responsible for the development of essential hypertension. One is a defect in the catecholamine storage complex resulting in a small store and the other an increase in the sodium concentration in vascular smooth muscle. The former, in our view, is the basic hereditary defect although its exact chemical nature remains to be elucidated. The latter is produced by several factors including increased vasoconstriction itself, increased ingestion of salt, etc. 2. Increased vascular reactivity in essential hypertension may be the result of the small 1-norepinephrine (NE) store. If tissue sodium is sufficiently increased, it can contribute further to the increased responsiveness. Increased sympathetic nerve discharge, as produced by anxiety, compounds the difficulties in this context by producing further vasoconstriction, greater decrease in NE stores and more sodium accumulation, whereas in normotensive subjects, modulating factors are sufficient to absorb such impact. 3. There is some evidence that angiotensin II (AT) may enter the NE storage pool. If it does, the increased AT pool may account for the slow turnover of AT in essential hypertension. Serum angiotensinase activity, however, is apparently augmented by a greater than normal amount of AT in the body of the hypertensive subject. The AT is not sufficiently increased to produce much direct vasoconstriction but may act on tissue sodium via a direct effect on the kidney and also via stimulation of aldosterone production by the adrenal cortex.
The conversion of carboxylic acids to amides via tin(II) reagents

Abstract Unsymmetrical tin(II) amides can be generated, in situ, by adding one equivalent of an amine to bis(bistrimethylsilylamino) tin, Sn[N(TMS)2]2. Treatment of carboxylic acids with these tin(II) reagents derived from alkyl or aryl amines results in smooth conversion to the corresponding N-alkyl or N-aryl amides.
Edge separability based circuit clustering with application to circuit partitioning

In this paper, we introduce a new efficient O(n log n) graph search based bottom-up clustering algorithm named ESC (Edge Separability based Clustering). Unlike existing bottom-up algorithms that are based on local connectivity information of the netlist, ESC exploits more global connectivity information "edge separability" to guide clustering process while carefully monitoring cluster area balance. Computing the edge separability for a given edge e=(x, y) in an edge weighted undirected graph G(V, E, s, w) is equivalent to finding the x-y mincut. Then, we show that a simple and efficient algorithm CAPFOREST can be used to provide a good estimation of edge separability for all edges in G without using any network flow computation. Related experiments based on large scale ISPD98 benchmark circuits confirm that exploiting edge separability yields better quality partitioning solution compared to various bottom-up clustering algorithms proposed in the literature including Absorption, Density, Rent Parameter, Ratio Cut, Closeness, and Connectivity method. In addition, our ESC based multiway partitioning algorithm LR/ESC-PM provides comparable results to state-of-the-art hMetis and hMetis-Kway.
Kernel and Offspring Concepts for the Stability Robustness of Multiple Time Delayed Systems (MTDS)

A novel treatment for the stability of linear time invariant (LTI) systems with rationally independent multiple time delays is presented in this paper. The independence of delays makes the problem much more challenging compared to systems with commensurate time delays (where the delays have rational relations). We uncover some wonderful features for such systems. For instance, all the imaginary characteristic roots of these systems can be found exhaustively along a set of surfaces in the domain of the delays. They are called the "kernel" surfaces (curves for two-delay cases), and it is proven that the number of the kernel surfaces is manageably small and bounded. All possible time delay combinations, which yield an imaginary characteristic root, lie either on this kernel or its infinitely many "offspring" surfaces. Another hidden feature is that the root tendencies along these surfaces exhibit an invariance property. From these outstanding characteristics an efficient, exact, and exhaustive methodology results for the stability assessment. As an added uniqueness of this method, the systems under consideration do not have to be stable for zero delays. Several example case studies are presented, which are prohibitively difficult, if not impossible to solve using any other peer methodology known to the authors.
Bubbles and Crises

In recent financial crises a bubble, in which asset prices rise, is followed by a collapse and widespread default. Bubbles are caused by agency relationships in the banking sector. Investors use money borrowed from banks to invest in risky assets, which are relatively attractive because investors can avoid losses in low payoff states by defaulting on the loan. This risk shifting leads investors to bid up the asset prices. Risk can originate in both the real and financial sectors. Financial fragility occurs when positive credit expansion is insufficient to prevent a crisis.
Variations on a theme of Jost and Pais

Abstract We explore the extent to which a variant of a celebrated formula due to Jost and Pais, which reduces the Fredholm perturbation determinant associated with the Schrodinger operator on a half-line to a simple Wronski determinant of appropriate distributional solutions of the underlying Schrodinger equation, generalizes to higher dimensions. In this multi-dimensional extension the half-line is replaced by an open set Ω ⊂ R n , n ∈ N , n ⩾ 2 , where Ω has a compact, nonempty boundary ∂ Ω satisfying certain regularity conditions. Our variant involves ratios of perturbation determinants corresponding to Dirichlet and Neumann boundary conditions on ∂ Ω and invokes the corresponding Dirichlet-to-Neumann map. As a result, we succeed in reducing a certain ratio of modified Fredholm perturbation determinants associated with operators in L 2 ( Ω ; d n x ) , n ∈ N , to modified Fredholm determinants associated with operators in L 2 ( ∂ Ω ; d n − 1 σ ) , n ⩾ 2 . Applications involving the Birman–Schwinger principle and eigenvalue counting functions are discussed.
Advanced technologies for a compact rf linac FEL

Abstract Advanced technologies such as photoinjectors, short-period microwigglers, and harmonic lasing enable free-electron-laser operation in the infrared with a low-energy (∼ 10 MeV) electron beam and thus potentially reduce the size and cost of FELs. The next-generation, rf-linac FEL will fit in a small laboratory and produce high-power, picosecond infrared.
A family of bioreducible poly(disulfide amine)s for gene delivery

A family of bioreducible poly(disulfide amine)s, which differ in the length of polymethylene spacer [-(CH(2))(n)-] in the main chain and the side chain, has been synthesized. These bioreducible poly(disulfide amine)s exhibit local environment specific degradability and are associated with lower cytotoxicity than branched poly(ethylenimine) (bPEI, 25 kDa). These cationic polymers also show higher buffering capacity and protonation degree than bPEI, facilitating the endosomal escape of carried genetic materials. The transfection efficiency of these agents is oligomethylene length dependent. Poly(cystaminebisacrylamide-spermine) [poly(CBA-SP)], poly(cystaminebisacrylamide-bis(3-aminopropyl)-1,3-propanediamine) [poly(CBA-APPD)], and poly(cyxtaminebisacrylamide-bis(3-aminopropyl)-ethylenediamine) [ploy(CBA-APED)] with longer propylene [-(CH(2))(3)-] side spacer, demonstrate higher transfection efficacy than the counterpart poly(cystaminebisacrylamide-bis(2-aminoethyl)-1,3-propanediamine) [poly(CBA-AEPD)] and poly(cystaminebisacrylamide-triethylenetetramine) [poly(CBA-TETA)], which have shorter ethylene [-(CH(2))(2)-] side spacer. The poly(CBA-SP), poly(CBA-APPD), poly(CBA-APED) with the main chain spacer of -(CH(2))(4)-, -(CH(2))(3)-, -(CH(2))(2)- demonstrate similar transfection efficiency, indicating the length of polymer main chain spacer has less influence on transfection efficiency. However, with the same short ethylene [-(CH(2))(2)-] side spacer, poly(CBA-AEPD), with the longer main chain oligomethylene units [-(CH(2))(3)-], showed relatively higher transfection efficiency than poly(CBA-TETA), having shorter main chain oligomethylene units [-(CH(2))(2)-]. Of these polymeric carriers, poly(CBA-SP) demonstrated the highest transfection in the C2C12 cell line, while poly(CBA-APED) showed the highest transfection in the HeLa cell line. All of these agents showed greater transfection activity than commercialized bPEI 25 kDa. The poly(disulfide amine)s are promising safe and efficient non-viral vectors for gene delivery.
Inconsistencies in interpreting the atmospheric neutrino anomaly

We note a discrepancy between the value ofR expected on the basis of the muon neutrino angular distribution and the value actually observed. The energy independence ofR leads to a fine-tuning problem. This may be indicative of some unaccounted for new physics.
Pioneer 10 observation of the solar wind proton temperature heliocentric gradient

Solar wind isotropic proton temperatures as measured out to 12.2 AU heliocentric distance by the Ames plasma analyzer aboard Pioneer 10 are presented as consecutive averages over three Carrington solar rotations and discussed. The weighted least-squares fit of average temperature to heliocentric radial distance, R, yields the power law R sup -.52. These average proton temperatures are not correlated as well with Pioneer 10's heliocentric radial distance (-.85) as are the corresponding average Zurich sunspot numbers R sub z (-.95). Consequently, it is difficult to isolate the spatial gradient in the Pioneer 10 solar wind proton temperatures using that data alone.
Interpreting the relationship between galaxy luminosity, color, and environment

We study the relationship between galaxy luminosity, color, and environment in a cosmological simulation of galaxy formation. Using a simple prescription to assign colors and luminosities to simulated galaxies, we compare the predicted relationship with that observed for SDSS galaxies and find that the model successfully predicts most of the qualitative features seen in the data, but also shows some interesting differences. Specifically, the simulation predicts that the local density around bright red galaxies is a strong increasing function of luminosity, but does not depend much on color at fixed luminosity. Moreover, we show that these trends are due to central galaxies in dark matter halos whose baryonic masses correlate strongly with halo mass. The simulation also predicts that the local density around blue galaxies is a strong increasing function of color, but does not depend much on luminosity at fixed color. We show that these trends are due to satellite galaxies in halos whose stellar ages correlate with halo mass. Finally, the simulation fails to predict the luminosity dependence of environments observed around low-luminosity red galaxies. However, we show that this is most likely due to the simulation's limited resolution. A study of a higher resolution, smaller volume simulation suggests that this dependence is caused by the fact that all low-luminosity red galaxies are satellites in massive halos, whereas intermediate-luminosity red galaxies are a mixture of satellites in massive halos, and central galaxies in less massive halos.
The MIT X-ray laser project

Abstract Recent advances in accelerator, laser, and undulator technology have created the possibility of constructing a national user facility based on an intense free-electron laser at extreme ultraviolet and X-ray wavelengths. MIT is exploring the construction of such a facility at its Bates Laboratory site, 20 miles north of Cambridge. The science that is foreseen spans many disciplines including atomic and fundamental physics, condensed matter physics and materials sciences, femtochemistry, structural biology, and various fields of engineering. The source we propose, and the experimental methods it will spawn, will generally be qualitatively new and have high impact in many fields of science and technology. The strength of the science and technology base in the northeast region, and in particular at MIT, make this a superb location for such a national user facility.
A Placebo Controlled Double Blind Study Using Perioperative Prazosin in the Prevention of Urinary Retention Following Inguinal Hernia Repair

Acute urinary retention is a frequent complication following inguinal hernia repair. The smooth muscle of the bladder neck and the prostate have been demonstrated to be rich in alpha-1 adrenergic receptors. It has been postulated that the aetiology of acute urinary retention postoperatively is at least partially due to adrenergic stimulation, blocking these receptors may reduce the incidence of acute urinary retention. We have used prazosin in a double blind, placebo controlled study to establish its efficacy in the prevention of acute urinary retention in patients undergoing elective inguinal hernia repair. A total of 70 male patients were enrolled; 36 patients had been allocated active drug and 34 patients had been allocated placebo. Only two patients developed acute urinary retention. Both patients had been allocated prazosin and had received a general anaesthetic for their hernia surgery. In either arm of the study, a higher number of patients developing urinary retention would have been expected but this may be explained by the greater vigilance on urinary output by nursing staff aware that the trial was being conducted. On the basis of our findings, we do not recommend the routine use of perioperative prazosin with inguinal hernia repair. Further studies in high risk groups would be necessary to assess more fully the efficacy of prazosin in this situation.
Friction Damping and Isolation Systems

This paper surveys the literature on the use of dry friction in passive damping and vibration isolation. Several analytical techniques are presented followed by applications from various areas. Despite difficulties in the analytical and experimental treatment of friction damped systems, numerous studies have endeavored to predict, measure, and/or enhance the energy dissipation and vibration isolation properties of dry friction in order to improve system performance. Undoubtedly, friction damping will continue to play an important role in many mechanical and structural systems.
Flat-top oscillons in an expanding universe

Oscillons are extremely long lived, oscillatory, spatially localized field configurations that arise from generic initial conditions in a large number of nonlinear field theories. With an eye towards their cosmological implications, we investigate their properties in an expanding universe. We (1) provide an analytic solution for one-dimensional oscillons (for the models under consideration) and discuss their generalization to three dimensions, (2) discuss their stability against long wavelength perturbations, and (3) estimate the effects of expansion on their shapes and lifetimes. In particular, we discuss a new, extended class of oscillons with surprisingly flat tops. We show that these flat-topped oscillons are more robust against collapse instabilities in (3+1) dimensions than their usual counterparts. Unlike the solutions found in the small amplitude analysis, the width of these configurations is a nonmonotonic function of their amplitudes.
A Synthesis of β-necrodol via a palladium catalyzed reductive enyne cyclization

Abstract The Pd catalyzed reductive enyne cyclization provides an approach to control 1,3- diastereoselectivity and thereby provides a five step synthesis of β-necrodol, a key substituent of the defensive secretion of the red-lined carrion beetle.
Redeeming bad theories

We give a Seiberg-like dual description of the interacting superconformal infrared fixed point of $ \mathcal{N}=4 $ gauge theory in three dimensions with vanishing Chern Simons level and N c ≤ N f < 2N c fundamental flavors. These theories are known as “bad” theories due to the existence of unitarity violating monopole operators. We show that, in a dual description, all such operators are realized by free fields and the remainder theory is the Seiberg-like dual previously identified using the type IIB brane construction.
IMAGING STARSPOT EVOLUTION ON KEPLER TARGET KIC 5110407 USING LIGHT-CURVE INVERSION

The Kepler target KIC 5110407, a K-type star, shows strong quasi-periodic light curve fluctuations likely arising from the formation and decay of spots on the stellar surface rotating with a period of 3.4693 days. Using an established light-curve inversion algorithm, we study the evolution of the surface features based on Kepler space telescope light curves over a period of two years (with a gap of .25 years). At virtually all epochs, we detect at least one large spot group on the surface causing a 1%-10% flux modulation in the Kepler passband. By identifying and tracking spot groups over a range of inferred latitudes, we measured the surface differential rotation to be much smaller than that found for the Sun. We also searched for a correlation between the 17 stellar flares that occurred during our observations and the orientation of the dominant surface spot at the time of each flare. No statistically significant correlation was found except perhaps for the very brightest flares, suggesting that most flares are associated with regions devoid of spots or spots too small to be clearly discerned using our reconstruction technique. While we may see hints of long-term changes in the spot characteristics and flare statisticsmore » within our current data set, a longer baseline of observation will be needed to detect the existence of a magnetic cycle in KIC 5110407.« less
The Two-Phase Accelerometer

A direct measurement of shaft angular acceleration may be made with a conventional drag cup tachometer operated as an accelerometer. In this operating mode the tachometer is supplied with direct current and provides a direct voltage proportional to acceleration. This paper presents the theory of operation, experimental accelerometer characteristics of a commercial tachometer, and a number of interesting applications of this novel device.
Age and bone mass in premenopausal women

It is important to determine the bone mass in normal premenopausal women because increasing numbers of conditions have been identified that result in premenopausal osteoporosis. The relationship between age and bone density was evaluated in 57 carefully characterized normal, premenopausal women using both single energy quantitative computed tomography (SEQCT) and dual energy (DEQCT). The mean bone density measurements were 172 mg/ml K2HPO4 SEQCT and 185 DEQCT. Bone density showed no statistically significant decline between age 18 and age 44. Single- and dual-energy data were highly correlated with each other (r = 0.89), and dual energy appeared to confer no advantage. There was an inverse relation between density and age of menarche. Bone density did not correlate with ideal body weight, percentage fat, or subcutaneous fat area.
Solar Energy Storage Using Reversible Hydration-Dehydration of CaO-Ca(OH)2

AS an approximate measure of the attractiveness of CaOCa (OH) 2 as a heat storage material, when CaO is hydrated with low pressure exhaust steam, ~44xl0 6 J of heat are obtained at a constant and high temperature level (430-540°C) from 0.028 m3 of CaO in bulk storage. Experimental results obtained to date on the CaO-Ca(OH)2 material include material characterization (chemical composition, particle size and surface area, and porosity) before and after reaction cycling. Three 8-g Ca(OH)2 samples were alternately dehydrated and hydrated up to, in one case, 1171 times, and the degree of completion of the reaction was measured periodically. The activation energy and the heat of reaction were measured using a pressure differential scanning calorimeter and were found to correspond closely with reported values. System studies were conducted on selected CaO-Ca(OH)2 thermochemical energy storage systems for a 100-MW commercial, solar-powered, thermal-electric generating station. Results indicate that, for the storage concepts considered, the CaO-Ca(OH)2 storage system is more complex and higher in cost than a high temperature (593 °C) sensible heat storage system using liquid sodium (unless long storage times of ~ 14 h or more are needed), but is lower in cost than a low temperature (316°C) sensible heat storage system such as hot rocks and HT-43 oil. Contents The experimental work deals primarily with the characterization of the properties of CaO-Ca(OH)2 under conditions typical of a fixed-bed reactor system. An apparatus was designed and constructed for performing multiple reaction cycles. The temperature of 8-g of Ca(OH)2 powder is raised to ~550°C. The water vapor driven off is condensed, and the volume is measured as a function of time. For the hydration cycle, boiling water at about 110°C supplies the water vapor. Table 1 shows selected results of cycling one of the samples to 1171 cycles. Gradual losses of utilization were observed at intervals during the course of the experiment, but it was found that a rapid re-evacuation of the apparatus immediately restored the utilization of the material to the 90% level or greater. This behavior is hypothesized to be the result of the accumulation of noncondensibl es, largely from air in-leakage, and some of which may be generated from a corrosion
Darknet-Based Inference of Internet Worm Temporal Characteristics

Internet worm attacks pose a significant threat to network security and management. In this work, we coin the term Internet worm tomography as inferring the characteristics of Internet worms from the observations of Darknet or network telescopes that monitor a routable but unused IP address space. Under the framework of Internet worm tomography, we attempt to infer Internet worm temporal behaviors, i.e., the host infection time and the worm infection sequence, and thus pinpoint patient zero or initially infected hosts. Specifically, we apply statistical estimation techniques and propose method of moments, maximum likelihood, and linear regression estimators. We show analytically and empirically that our proposed estimators can better infer worm temporal characteristics than a naive estimator that has been used in the previous work. We also demonstrate that our estimators can be applied to worms using different scanning strategies such as random scanning and localized scanning.
Multi-Frequency Cobweb Model: Decomposition of the Hog Cycle

The Cobweb Theorem and the harmonic motion models are extended and integrated to form a multi-frequency cobweb model explaining the U. S. hog production cycle. The cycle is estimated by a finite, time-based Fourier Series allowing amplitude and frequency analysis. Six different cycles are discovered operating simultaneously in the attempt to reach a market equilibrium. An independent distributed lag model is estimated, verifying the fundamental hypothesis of the model. The implication is that improved industry performance can be efficiently achieved by control policies to dampen the harmful long period cycles, leaving the short ones unaffected.
The effects of hydrogen bonds on metal-mediated O2 activation and related processes.

Hydrogen bonds stabilize and direct chemistry performed by metalloenzymes. With inspiration from enzymes, we will utilize an approach that incorporates intramolecular hydrogen bond donors to determine their effects on the stability and reactivity of metal complexes. Our premise is that control of secondary coordination sphere interactions will promote new function in synthetic metal complexes. Multidentate ligands have been developed that create rigid organic structures around metal ions. These ligands place hydrogen bond (H-bond) donors proximal to the metal centers, forming specific microenvironments. One distinguishing attribute of these systems is that site-specific modulations in structure can be readily accomplished, in order to evaluate correlations with reactivity. A focus of this research is consideration of dioxygen binding and activation by metal complexes, including developing structure–function relationships in metal-assisted oxidative catalysis.
Computer application of electro-optics

The first few years of existence of electro-optics as a separate field have brought to light a wealth of novel ideas and has warmed up a host of old ones as well. It turns out that at this time there are two large classes of ideas which have relatively little overlap: the first class encompasses the development of time-honored techniques into practical low-cost designs; the second class contains the more futuristic devices using laser amplification, laser logic, laser source deflection, etc. Unluckily the latter ideas have not yet reached that stage of development where they can compete with more classical designs as far as cost is concerned. Since the author has devoted a previous paper to them, it might be useful to examine all those areas where patient development has produced reasonably low-cost designs that have proved themselves in practice or are about to do so.
Medulloblastoma in adults. Improved survival with supervoltage radiation therapy

During the period from January 1962--June 1979, 17 adults (greater than or equal to 16 years of age) received postoperative supervoltage neuraxis radiation therapy for medulloblastoma. An actuarial five- and ten-year survival rate of 46% was achieved, and the major site of recurrence postirradiation was in the posterior fossa. Compared to previous pediatric series, adults may demonstrate more visceral metastases and fare less well after tumor recurrence. Compared to prior series of adult patients, the demonstrated improved survival is attributed to increased doses delivered to the posterior fossa.
Cation Exchange: A Versatile Tool for Nanomaterials Synthesis

The development of nanomaterials for next generation photonic, optoelectronic, and catalytic applications requires a robust synthetic toolkit for systematically tuning composition, phase, and morphology at nanometer length scales. While de novo synthetic methods for preparing nanomaterials from molecular precursors have advanced considerably in recent years, postsynthetic modifications of these preformed nanostructures have enabled the stepwise construction of complex nanomaterials. Among these postsynthetic transformations, cation exchange reactions, in which the cations ligated within a nanocrystal host lattice are substituted with those in solution, have emerged as particularly powerful tools for fine-grained control over nanocrystal composition and phase. In this feature article, we review the fundamental thermodynamic and kinetic basis for cation exchange reactions in colloidal semiconductor nanocrystals and highlight its synthetic versatility for accessing nanomaterials intractable by direct synthet...
Obligation and Joint Commitment

We speak of ‘obligations’ in many contexts. But what are obligations? I argue that obligations of an important type inhere in what I call ‘joint commitments’. I propose a joint commitment account of everyday agreements. This could explain why some philosophers believe that we know of the obligating nature of agreements a priori. I compare and contrast obligations of joint commitment with obligations in the relatively narrow sense recommended by H. L. A. Hart, a recommendation that has been influential. Some central contexts in which Hart takes there to be obligations in his sense are contexts in which there are obligations of joint commitment. Nonetheless different senses of ‘obligation’ appear to be at issue.
Radial seismic anisotropy as a constraint for upper mantle rheology

Abstract Seismic shear waves that are polarized horizontally (SH) generally travel faster in the upper mantle than those that are polarized vertically (SV), and deformation of rocks under dislocation creep has been invoked to explain such radial anisotropy. Convective flow of the upper mantle may thus be constrained by modeling the textures that progressively form by lattice-preferred orientation (LPO) of intrinsically anisotropic grains. While azimuthal anisotropy has been studied in detail, the radial kind has previously only been considered in semi-quantitative models. Here, we show that radial anisotropy averages as well as radial and azimuthal anomaly-patterns can be explained to a large extent by mantle flow, if lateral viscosity variations are taken into account. We construct a geodynamic reference model which includes LPO formation based on mineral physics and flow computed using laboratory-derived olivine rheology. Previously identified anomalous v SV regions beneath the East Pacific Rise and relatively fast v SH regions within the Pacific basin at ~ 150 km depth can be linked to mantle upwellings and shearing in the asthenosphere, respectively. Continental anisotropy at shallow (~ 50 km) depth is under-predicted, and these deviations are in quantitative agreement with the expected signature of frozen-in, stochastically-oriented anisotropy from past tectonic episodes. We also consider two end-member models of LPO formation for “wet” and “dry” conditions for the asthenosphere (~ 150 km). Allowing for lateral variations in volatile content, the residual signal can be much reduced, and the inferred volatile patterns underneath the Pacific appear related to plume activity. In deeper layers (~ 250 km), anisotropy indicates that small-scale convection disrupts plate-scale shear underneath old oceanic lithosphere. We suggest that studying deviations from comprehensive geodynamic reference models, or “residual anisotropy”, can provide new insights into the nature and dynamics of the asthenosphere.
What firms know

A large literature shows that the legal tradition of a country is highly correlated with various dimensions of institutional quality. Broadly, studies show that English common law countries perform better than the French civil law countries with respect to the regulatory burden on firms, efficiency of courts and contract enforcement, corruption and overall governance. The present paper adds to this literature by showing another aspect of institutional development that conforms to the same pattern. That is, ease with which information on laws and regulations is available to firms is superior in common law compared with civil law countries. Roughly, one-third of this difference can be explained by differences in the level of business regulations across the two legal traditions. Among other factors, the author finds that larger firms and smaller countries report much better availability of information than their respective counterparts. The author provides some plausible reasons for these findings. The paper is as follow. In section two the author describes their data and the main variables. Main empirical results are provided in section three and robustness checks in section four. The concluding section provides a summary of the important results.
Dynamics of a family of piecewise-linear area-preserving plane maps II. Invariant circles

This paper studies the behavior under iteration of the maps T ab (x, y) = (F ab (x) − y, x) of the plane in which F ab (x) = ax if x ≥ 0 and bx if x < 0. The orbits under iteration correspond to solutions of the difference equation This family of piecewise-linear maps of the plane has the parameter space These maps are area-preserving homeomorphisms of that map rays from the origin into rays from the origin. We show the existence of special parameter values where T ab has every nonzero orbit contained in an invariant circle with an irrational rotation number, with invariant circles that are piecewise unions of arcs of conic sections. Numerical experiments indicate the possible existence of invariant circles for many other parameter values.