cssi/SciSciGPT-SciSciNet huggingface dataset:
Neoplasia after ureterosigmoidostomy

PURPOSE: The occurrence of neoplasia after ureterosigmoidostomy is well-documented in the literature. Because of its rarity, few general surgeons will gain significant exposure to this entity, and colorectal surgeons are likely to be involved with the care of these patients. The purpose of this article is to apprise colorectal surgeons about the management of neoplasia after ureterosigmoidostomy and to familiarize them with the unique anatomy of the reconstructed pelvis. METHODS: We performed a MEDLINE search to identify articles on ureterosigmoid tumors. The theories regarding the cause and pathology of these tumors were critically analyzed. A consensus was developed for screening patients with ureterosigmoidostomy and for treatment of neoplasia. RESULTS: The incidence of carcinoma after ureterosigmoidostomy ranges from 2 to 15 percent. Polyps are more common, and it seems that these tumors also follow the sequence of adenocarcinoma that is seen in the common variety of colorectal neoplasia. Neoplastic changes begin with the interaction of urine and feces and the healing colonic mucosa. Both production of nitrosamines by the action of bacteria on urine and DNA damage caused by reactive oxygen radicals produced by neutrophils at the healing anastomosis have been implicated in the pathogenesis of neoplasia. The latent period between formation of ureterosigmoidostomy and the appearance of carcinoma is between 20 and 26 years. Obstructive urinary symptoms that develop more than two years after ureterosigmoidostomy should be viewed with suspicion. The patient should be investigated with a CT scan and colonoscopy, and a barium enema may be required to delineate the anatomy further. If a benign tumor is encountered during colonoscopy, it may be removed by snare polypectomy. For a malignant tumor the segment of colon with ureteric implants should be excised, along with its lymphatic drainage. Bowel continuity is restored primarily, and the ureters are implanted in an ileal conduit. CONCLUSIONS: Patients with ureterosigmoidostomy should be followed closely for the rest of their lives. The aim of screening is to identify and treat neoplasia before malignancy develops. Furthermore, early detection of neoplasia by close screening will improve survival. Although urine cytology and occult blood are inexpensive tests, colonoscopy remains the criterion standard for follow-up of these patients. Annual colonoscopic surveillance should be started soon after the ureterosigmoidostomy but not later than five to six years after the procedure. Patients who are noncompliant with the vigorous follow-up schedule should be offered the option of resection of the colonic segment at risk with urinary diversion.
Bit-Interleaved Coded Multiple Beamforming with Constellation Precoding

In this paper, we present the diversity order analysis of bit-interleaved coded multiple beamforming (BICMB) combined with the constellation precoding scheme. Multiple beamforming is realized by singular value decomposition of the channel matrix which is assumed to be perfectly known to the transmitter as well as the receiver. Previously, BICMB is known to have a diversity order bound related with the product of the code rate and the number of parallel subchannels, losing the full diversity order in some cases. In this paper, we show that BICMB combined with the constellation precoder and maximum likelihood detection achieves the full diversity order. We also provide simulation results that match the analysis.
Can affirmative action be cost effective? : an experimental examination of price-preference auctions

One of the most controversial questions facing our economy and society in recent years is the question of affirmative action. The debate centers around an issue of minority representation in which the rights of the majority are depicted as being compromised by affirmative action programs set up to increase the welfare of minorities. Implicit in this discussion is the assumption that all affirmative action programs must be cost increasing. This result, it is claimed, follows trivially from economic theory since any interference into the competitive process which prevents the most capable from being chosen must be wasteful and costly. In this paper we challenge this claim with experimental results, demonstrating that pricepreference auctions, in which high-cost minority firms are given preferential treatment in the awarding of contracts in such a way that it is possible for these firms to win a contract but not have submitted the lowest bid, can be programs that both enhance minority representation and are cost effective in that they decrease the cost of government procurement. In the theoretical literature on asymmetric auctions (Eric Maskin and John Riley, 1995) and the optimal auction literature ( Roger Myerson, 1981) it has been shown that in asymmetric auctions, in which firms draw their costs from
On tree amplitudes in gauge theory and gravity

The BCFW recursion relations provide a powerful way to compute tree amplitudes in gauge theories and gravity, but only hold if some amplitudes vanish when two of the momenta are taken to infinity in a particular complex direction. This is a very surprising property, since individual Feynman diagrams all diverge at infinite momentum. In this paper we give a simple physical understanding of amplitudes in this limit, which corresponds to a hard particle with (complex) light-like momentum moving in a soft background, and can be conveniently studied using the background field method exploiting background light-cone gauge. An important role is played by enhanced spin symmetries at infinite momentum-a single copy of a ``Lorentz group for gauge theory and two copies for gravity-which together with Ward identities give a systematic expansion for amplitudes at large momentum. We use this to study tree amplitudes in a wide variety of theories, and in particular demonstrate that certain pure gauge and gravity amplitudes do vanish at infinity. Thus the BCFW recursion relations can be used to compute completely general gluon and graviton tree amplitudes in any number of dimensions. We briefly comment on the implications of these results for computing massive 4D amplitudes by KK reduction, as well understanding the unexpected cancelations that have recently been found in loop-level gravity amplitudes.
Redetermination of crystal structure of zinc thiogallate

Abstract Zinc thiogallate crystallizes in the tetragonal space group I 4 2m with a = 5.297(1), c = 10.363(1) A . In this space group zinc and gallium are disordered in the 4(d) sites. Most of the AGa2X4 compounds crystallize with the defect chalcopyrite, space group I 4 where the A and Ga ions are ordered and half of the A-sites are vacant. The result of this work indicates that disordering of Zn and Ga ions can occur and result in a structure with higher symmetry. All of these compounds transmit in the far infrared and are potential infrared window materials.
The Taylor Rule and “Opportunistic” Monetary Policy

We investigate the possibility that the Taylor rule should be formulated as a threshold process such that the Federal Reserve acts more aggressively in some circumstances than in others. It seems reasonable that the Federal Reserve would act more aggressively when inflation is high than when it is low. Similarly, it might be expected that the Federal Reserve responds more to a negative than a positive output gap. Although these specifications receive some empirical support, we find that a modified threshold model that is consistent with “opportunistic” monetary policy makes significant progress toward explaining Federal Reserve behavior.
Chemotactic Factors Induced Vimentin Phosphorylation in Rabbit Peritoneal Neutrophil

Rabbit peritoneal neutrophils were reacted for 5-10 s with the chemotactic factors, fMet-Leu-Phe or (5S),(12R)-dihydroxy-6,8,11,14-(cis,trans,trans,cis)-eicosatetraenoic acid and then lysed with a solution of Triton X-100 and [gamma-32P]ATP. They showed an enhanced incorporation of 32P in Mr = 60,000- and 67,000-dalton polypeptides compared to control cells treated similarly. Another chemotactic factor, C5a, produced a similar but much lesser effect. The enhancement was not affected by the addition of the purified catalytic subunit of cAMP-dependent protein kinase, the inhibitor of cAMP-dependent protein kinase, or CaCl2, suggesting that the effect was not mediated by a cAMP-dependent or a Ca2+-dependent protein kinase. When analyzed by two-dimensional gel electrophoresis, the Mr = 60,000 phosphoprotein contained several phosphoproteins with different isoelectric points. The isoelectric point and molecular weight of one of them was similar to those of the intermediate filament protein, vimentin, purified from Chinese hamster ovary cells. Addition of the purified Chinese hamster ovary vimentin and [gamma-32P]ATP to the Triton X-100 lysate of fMet-Leu-Phe-treated neutrophils resulted as an enhanced incorporation of 32P into the vimentin. Addition of fMet-Leu-Phe to 32P-labeled intact neutrophils also enhanced incorporation of 32P into the vimentin of neutrophils. The results suggest that chemotactic factors stimulate vimentin phosphorylation in rabbit neutrophils.
Inflation and Relative Price Variability in Mexico: The Role of Remittances

This article derives generalized impulse responses from the estimation of a vector autoregression (VAR) model using monthly data between 1995 and 2005 for Mexico, to examine the inflation–relative price variability (RPV) relationship, and to investigate if remittances could account for the observed relationship. While the positive relationship between inflation and RPV is a robust result, remittances are found to have significant positive effects on both inflation and RPV. These results are interpreted as providing evidence in support of our intuition that remittances could be responsible for generating a positive relationship between inflation and RPV.
An efficient method for computing unsteady transonic aerodynamics of swept wings with control surfaces

A transonic equivalent strip (TES) method was further developed for unsteady flow computations of arbitrary wing planforms. The TES method consists of two consecutive correction steps to a given nonlinear code such as LTRAN2; namely, the chordwise mean flow correction and the spanwise phase correction. The computation procedure requires direct pressure input from other computed or measured data. Otherwise, it does not require airfoil shape or grid generation for given planforms. To validate the computed results, four swept wings of various aspect ratios, including those with control surfaces, are selected as computational examples. Overall trends in unsteady pressures are established with those obtained by XTRAN3S codes, Isogai's full potential code and measured data by NLR and RAE. In comparison with these methods, the TES has achieved considerable saving in computer time and reasonable accuracy which suggests immediate industrial applications.
Phase separation in t − J ladders

The phase separation boundary of isotropic $t\ensuremath{-}J$ ladders is analyzed using density matrix renormalization group techniques. The complete boundary to phase separation as a function of $J/t$ and doping is determined for a chain and for ladders with two, three, and four legs. Six-chain ladders have been analyzed at low hole doping. We use a direct approach in which the phase separation boundary is determined by measuring the hole density in the part of the system which contains both electrons and holes. In addition, we examine the binding energy of multihole clusters. An extrapolation in the number of legs suggests that the lowest $J/t$ for phase separation to occur in the two-dimensional $t\ensuremath{-}J$ model is $J/t\ensuremath{\sim}1.$
A combinatorial formula for rank 2 cluster variables

Let r be any positive integer, and let x 1,x 2 be indeterminates. We consider the sequence {x n } defined by the recursive relation $$x_{n+1} =\bigl(x_n^r +1\bigr)/{x_{n-1}}$$ for any integer n. Finding a combinatorial expression for x n as a rational function of x 1 and x 2 has been an open problem since 2001. We give a direct elementary formula for x n in terms of subpaths of a specific lattice path in the plane. The formula is manifestly positive, providing a new proof of a result by Nakajima and Qin.
Solving structure with sparse, randomly-oriented x-ray data

Single-particle imaging experiments of biomolecules at x-ray free-electron lasers (XFELs) require processing hundreds of thousands of images that contain very few x-rays. Each low-fluence image of the diffraction pattern is produced by a single, randomly oriented particle, such as a protein. We demonstrate the feasibility of recovering structural information at these extremes using low-fluence images of a randomly oriented 2D x-ray mask. Successful reconstruction is obtained with images averaging only 2.5 photons per frame, where it seems doubtful there could be information about the state of rotation, let alone the image contrast. This is accomplished with an expectation maximization algorithm that processes the low-fluence data in aggregate, and without any prior knowledge of the object or its orientation. The versatility of the method promises, more generally, to redefine what measurement scenarios can provide useful signal.
Synthesis and anti-acetylcholinesterase properties of novel β- and γ-substituted alkoxy organophosphonates

Abstract Activated organophosphate (OP) insecticides and chemical agents inhibit acetylcholinesterase (AChE) to form OP-AChE adducts. Whereas the structure of the OP correlates with the rate of inhibition, the structure of the OP-AChE adduct influences the rate at which post-inhibitory reactivation or aging phenomena occurs. In this report, we prepared a panel of β-substituted ethoxy and γ-substituted propoxy phosphonoesters of the type p- NO 2 PhO-P(X)(R)[(O(CH 2 ) n Z] (R = Me, Et; X = O, S; n = 2, 3; Z = halogen, OTs) and examined the inhibition of three AChEs by select structures in the panel. The β-fluoroethoxy methylphosphonate analog (R = Me, Z = F, n = 2) was the most potent anti-AChE compound comparable ( k i ∼6 × 10 6 M −1 min −1 ) to paraoxon against EEAChE. Analogs with Z = Br, I, or OTs were weak inhibitors of the AChEs, and methyl phosphonates (R = Me) were more potent than the corresponding ethyl phosphonates (R = Et). As expected, analogs with a thionate linkage (P S) were poor inhibitors of the AChEs.
The dynamical evolution of the Pleiades

We present the results of a numerical simulation of the history and future development of the Pleiades. This study builds on our previous one that established statistically the present-day structure of this system. Our simulation begins just after molecular cloud gas has been expelled by the embedded stars. We then follow, using an N-body code, the stellar dynamical evolution of the cluster to the present and beyond. Our initial state is that which evolves, over the 125 Myr age of the cluster, to a configuration most closely matching the current one. We find that the original cluster, newly stripped of gas, already had a virial radius of 4 pc. This configuration was larger than most observed, embedded clusters. Over time, the cluster expanded further and the central surface density fell by about a factor of 2. We attribute both effects to the liberation of energy from tightening binaries of short period. Indeed, the original binary fraction was close to unity. The ancient Pleiades also had significant mass segregation, which persists in the cluster today. In the future, the central density of the Pleiades will continue to fall. For the first few hundred Myr, the cluster as a whole will expand because of dynamical heating by binaries. The expansion process is aided by mass loss through stellar evolution, which weakens the system’s gravitational binding. At later times, the Galactic tidal field begins to heavily deplete the cluster mass. It is believed that most open clusters are eventually destroyed by close passage of a giant molecular cloud. Barring that eventuality, the density falloff will continue for as long as 1 Gyr, by which time most of the cluster mass will have been tidally stripped away by the Galactic field.
Cutting Into the Meatpacking Line: Workers and Change in the Rural Midwest

The nostalgic vision of a rural Midwest populated by independent family farmers hides the reality that rural wage labor has been integral to the region's development, says Deborah Fink. Focusing on the porkpacking industry in Iowa, Fink investigates the experience of the rural working class and highlights its significance in shaping the state's economic, political, and social contours. Fink draws both on interviews and on her own firsthand experience working on the production floor of a pork-processing plant. She weaves a fascinating account of the meatpacking industry's history in Iowa--a history, she notes, that has been experienced differently by male and female, immigrant and native-born, white and black workers. Indeed, argues Fink, these differences are a key factor in the ongoing creation of the rural working class. Other writers have denounced the new meatpacking companies for their ruthless destruction of both workers and communities. Fink sustains this criticism, which she augments with a discussion of union action, but also goes beyond it. She looks within rural midwestern culture itself to examine the class, gender, and ethnic contradictions that allowed--indeed welcomed--the meatpacking industry's development. |Drawing on firsthand experience working in an Iowa pork-processing plant, Fink looks at the differing experience of male and female, immigrant and native-born, black and white workers in the meatpacking industry.
Long-range correlations in sedimentation

Using particle image velocimetry we have measured the sedimentation dynamics of non-Brownian colloidal spheres over a wide range of low concentrations ( $\ensuremath{\varphi}\ensuremath{\le}0.05$) and sample cell sizes $W$. Fluctuations in the settling velocity show universal large-scale finite-range correlations, in the form of swirls, which depend simply on volume fraction and particle radius and follow $〈\ensuremath{\delta}{V}_{z}(0)\ensuremath{\delta}{V}_{z}(z){〉}^{1/2}\ensuremath{\simeq}{2.0V}_{\mathrm{sed}}{\ensuremath{\varphi}}^{1/3}\mathrm{exp}(\ensuremath{-}z/2\ensuremath{\xi})$, where $\ensuremath{\xi}\ensuremath{\simeq}20a{\ensuremath{\varphi}}^{\ensuremath{-}1/3}$. In turn, the predicted divergence of the velocity variance with increasing cell size $W$ is cut off in a universal way as $W$ exceeds the swirl size and is well represented by $〈\ensuremath{\delta}{V}_{z}^{2}(0){〉}^{1/2}{\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}2.0V}_{\mathrm{sed}}{\ensuremath{\varphi}}^{1/3}[1\ensuremath{-}\mathrm{exp}(\ensuremath{-}W/60a{\ensuremath{\varphi}}^{\ensuremath{-}1/3})]$.
Generalized characters of the symmetric group

Normalized irreducible characters of the symmetric group S(n) can be understood as zonal spherical functions of the Gelfand pair (S(n)×S(n),diagS(n)). They form an orthogonal basis in the space of the functions on the group S(n) invariant with respect to conjugations by S(n). In this paper we consider a different Gelfand pair connected with the symmetric group, that is an ?unbalanced? Gelfand pair (S(n)×S(n-1),diagS(n-1)). Zonal spherical functions of this Gelfand pair form an orthogonal basis in a larger space of functions on S(n), namely in the space of functions invariant with respect to conjugations by S(n-1). We refer to these zonal spherical functions as normalized generalized characters of S(n). The main discovery of the present paper is that these generalized characters can be computed on the same level as the irreducible characters of the symmetric group. The paper gives a Murnaghan?Nakayama type rule, a Frobenius type formula, and an analogue of the determinantal formula for the generalized characters of S(n).
Effective log Iitaka fibrations for surfaces and threefolds

We prove an analogue of Fujino and Mori’s “bounding the denominators” (Theorem 3.1 of Fujino and Mori, J Diff Geom 50:167–188, 2000) in the log canonical bundle formula (see also Theorem 8.1 of Prokhorov and Shokurov, J Algebraic Geom 18(1):151–199, 2009) for Kawamata log terminal pairs of relative dimension one. As an application we prove that for a klt pair (X,Δ) of Kodaira codimension one and dimension at most three such that the coefficients of Δ are in a DCC set \({\mathcal{A}}\), there is a natural number N that depends only on \({\mathcal{A}}\) for which \({\lfloor{N(K_X+\Delta)\rfloor}}\) induces the Iitaka fibration. We also prove a birational boundedness result for klt surfaces of general type.
Polycarpine dihydrochloride: A cytotoxic dimeric disulfide alkaloid from the indian ocean ascidian Polycarpa clavata

Abstract Polycarpine dihydrochloride ( 1 ),a new cytotoxic dimeric disulfide alkaloid, and four related compounds ( 2–5 ) have been isolated from extracts of the ascidian Polycarpa clavata (Hartman, 1919) collected in Western Australia. The structure of the new alkaloid was determined on the basis of comprehensive spectral studies and by interconversion to its free base and several degradation products. On silica chromatography, 1 was converted to the corresponding unstable free base ( 2 ) which decomposed, via cleavage of the disulfide bridge, into monomeric derivatives. Polycarpine dihydrochloride is cytotoxic against the human colon tumor cell line HCT-116 at 0.9 μg/ml.
Versatile synthesis of meso-aryloxy- and alkoxy-substituted porphyrins via palladium-catalyzed C-O cross-coupling reactions.

meso-Aryloxy- and alkoxy-substituted porphyrins were conveniently synthesized by direct reactions of meso-halogenated porphyrins with alcohols via palladium-catalyzed C−O cross-coupling reactions. Using a combination of palladium precursor Pd(OAc)2 or Pd2(dba)3 and phosphine ligand DPEphos or Xantphos allowed both 5-bromo-10,20-diarylporphyrin and 5,15-dibromo-10,20-diarylporphyrin, as well as their zinc complexes, to be effectively coupled with a variety of alcohols to give the corresponding mono- and bis-substituted meso-aryloxy/alkoxyporphyrins in moderate to high yields under mild conditions.
Development of universal proxy models for screening and optimization of cyclic pressure pulsing in naturally fractured reservoirs

Abstract Economic success of an IOR project primarily depends on the effectiveness of the selected method in the reservoir of interest and the way it is deployed. Due to the heavy computational work required for a large number of simulations, it is rather an arduous task to determine optimum design schemes for a given project. Proxy models that mimic reservoir models can potentially offer an opportunity to reduce the number of simulation runs and allow timely reservoir-management decisions to be made. In this study, a high-performance screening/optimization workflow is presented to narrow the ranges of possible scenarios to be modeled using conventional simulation. The workflow proposed starts with creating a knowledge base with simulations for a wide range reservoir characteristics and design scenarios. Then, neural-network based proxy models are trained with the knowledge base. Finally, the genetic algorithm is used to search for the optimum design scenario by evaluating the objective function via proxy models for increased computational efficiency. This workflow is applied to the cyclic pressure pulsing process with CO2 and N2 in naturally fractured reservoirs. Developed proxies are universal such that the range of their applicabilities is extended to a wide spectrum of reservoir characteristics, including initial conditions, well spacing and reservoir fluid types (heavy, black, and volatile). Proxy models proved to be able to predict critical performance indicators such as cumulative oil production, and oil flow rates within high levels of accuracy (with a correlation coefficient of 0.91 on average). The genetic algorithm is coupled with proxy models to maximize the discounted oil volume produced per injected volume for a specified period of operation. After utilizing the aforementioned workflow, it is possible to significantly reduce the computational time and manpower expended with an initial screening of the cyclic pressure pulsing process. In this way, more effective design strategies can be structured for the reservoir under consideration.
Tests of Statistical Significance and Background Estimation in Gamma-Ray Air Shower Experiments

In this paper we discuss established methods of significance calculation for testing the existence of a signal in the presence of unknown background and point out the limits of their applicability. We then introduce a new self-consistent scheme for source detection and discuss some of its properties. The method overcomes weaknesses of those used previously and allows incorporating background anisotropies by vetoing existing localized sources and sinks on the sky and compensating for known large-scale anisotropies. By giving an example using the Milagro gamma-ray observatory data, we demonstrate how the method can be employed to relax the detector stability assumption. The new method is universal and can be used with any large field-of-view detector, in which the object of investigation, steady or transient, point or extended, traverses its field of view.
Staggering towards a calculation of weak amplitudes

Abstract An explanation is given of the methods required to calculate hadronic matrix elements of the weak Hamiltonian using lattice QCD with staggered fermions. New results are presented for the 1-loop perturbative mixing of the weak interaction operators. New numerical techniques designed for staggered fermions are described. A preliminary result for the kaon B parameter is presented.
Origins of scaling in natural images

Abstract One of the most robust qualities of our visual world is the scale invariance of natural images. Not only has scaling been found in different visual environments, but the phenomenon also appears to be calibration-independent. This paper proposes a simple property of natural images which explains this robustness they are collages of regions corresponding to statistically independent “objects”. Evidence is provided for these objects having a power-law distribution of sizes within images, from which follows scaling in natural images. It is commonly suggested that scaling instead results from edges, each with power spectrum 1k/2 . This hypothesis is refuted by example.
Assessment of Two Low-Reynolds-Number k-e Models in Turbulent Boundary Layers with Surface Roughness

Cf = skin friction coefficient D = hydraulic diameter H = channel height k = turbulent kinetic energy ks = roughness height keq = equivalent sand roughness height k = normalized turbulent kinetic energy, k=u k eq = normalized equivalent sand roughness height, u keq= k s = normalized roughness height, u ks= Re = Reynolds number Re = Reynolds number based on momentum thickness Rt = turbulent Reynolds number, k=" t = time U = mean velocity Ue = edge velocity U = normalized velocity, U=u u = friction velocity uv = Reynolds shear stress u v = normalized Reynolds shear stress, uv=u W = channel width y = normal distance from the wall y = normalized distance from the wall, u y= U = roughness function = boundary-layer thickness " = dissipation rate of turbulent kinetic energy = momentum thickness = kinematic viscosity
Randomized anisotropic transform for nonlinear dimensionality reduction

An innovative method is introduced in this paper to significantly increase computational speed and to reduce memory usage, when applied to nonlinear methods and algorithms for dimensionality reduction (DR). Due to the incapability of linear DR methods in the preservation of data geometry, the need of effective nonlinear approaches has recently attracted the attention of many researchers, particularly from the Mathematics and Computer Science communities. The common theme of the current nonlinear DR approaches is formulation of certain matrices, called dimensionality reduction kernels (DRK) in terms of the data points, followed by performing spectral decomposition. Hence, for datasets of large size with data points that lie in some high dimensional space, the matrix dimension of the DRK is very large. Typical examples for the need of very high dimensional DRK arise from such applications as processing multispectral imagery data, searching desired text documentary data in the internet, and recognizing human faces from given libraries. For such and many other applications, the matrix dimension of the DRK is so large that computation for carrying out spectral decomposition of the DRK often encounters various difficulties, not only due to the need of significantly large read-only memory (ROM), but also due to computational instability. The main objective of this paper is to introduce the notion of the anisotropic transform (AT) and to develop its corresponding effective and efficient computational algorithms by integrating random embedding with the AT to formulate the randomized anisotropic transform (RAT), in order to reduce the size of the DRK significantly, while preserving local geometries of the given datasets. Illustrations with various examples will also be given in this paper to demonstrate that RAT algorithms dramatically reduce the ROM and CPU requirement, and thus allow fast processing, even on PC and potentially for handhold devices as well.
UV/Optical Nuclear Activity in the gE Galaxy NGC 1399

Using HST STIS, we have detected far-ultraviolet nuclear activity in the giant elliptical galaxy NGC 1399, the central and brightest galaxy in the Fornax I cluster. The source reached a maximum observed far-UV luminosity of ~1.2 × 1039 ergs s-1 in 1999 January. It was detectable in earlier HST archival images in 1996 (B band) but not in 1991 (V band) or 1993 (UV). It faded by a factor of ~4 by mid-2000. The source is almost certainly associated with the low-luminosity AGN responsible for the radio emission in NGC 1399. The properties of the outburst are remarkably similar to the UV-bright nuclear transient discovered earlier in NGC 4552 by Renzini and coworkers. The source is much fainter than expected from its Bondi accretion rate (estimated from Chandra high-resolution X-ray images), even in the context of "radiatively inefficient accretion flow" models, and its variability also appears inconsistent with such models. High spatial resolution UV monitoring is a valuable means to study activity in nearby LLAGNs.
A 106-dB SNR hybrid oversampling analog-to-digital converter for digital audio

An audio /spl Sigma//spl Delta/ analog-to-digital converter (ADC) with the loop filter implemented by continuous-time (CT) and discrete-time (DT) circuits is presented. A tuning circuit is used to compensate for changes in the RC product due to process skew, power supply, temperature and sampling rate variation. To eliminate errors caused by inter-symbol interference (ISI) in the CT feedback DAC, a return-to-zero (RTZ) switching scheme is applied on the error current of the CT integrator. The converter is fabricated in a 0.35-/spl mu/m CMOS process, and achieves 106-dB dynamic range, -99-dB THD+N.
The Transitory and Legacy Effects of the Rental Externality on House Price and Liquidity

It is widely believed that tenant-occupied houses do not show as well as owner-occupied or even vacant units and so are harder to sell. These short term or transitory marketing effects should disappear in subsequent sales by owner-occupiers. Overuse by tenants and poor maintenance by landlords, however may lead to longer term or legacy effects on value and liquidity. We use a 20 year data series on house transactions to estimate these separate effects in a simultaneous model of price and liquidity. The results reveal strong transitory renter effects on both value and liquidity consistent with lower buyer willingness-to-pay. We do not find persistent legacy effects from prior use as rental property. Instead, there appears to be unmeasured quality or a characteristic common to houses suitable for rent that leads to permanently lower market values regardless of previous use in that capacity.
Temperature Control of Physiological Dwarfing in Peach Seedlings.

ONE of the key problems in germination physiology is the mechanism of embryo ‘dormancy’ or rest. One aspect of this problem is the physiological dwarfing which has been reported to occur in the seedlings of woody plants, especially of such commercial fruits as peaches. These seeds normally require an extended period of low-temperature after-ripening to permit germination. However, if the seed-coat is removed from non-after-ripened seeds germination occurs, but the shoots of such plants are abnormal with telescoped internodes and leaves which may be deformed or sometimes reduced to a rosette of white, scale-like appendages1,2; the exact symptoms are a varietal characteristic3. Low-temperature after-ripening of the seed or seedling is commonly reported to be essential to produce a normal plant.
Correlation of color Doppler flow in the prostate with tissue microvascularity.

BACKGROUND The pathophysiology of increased color Doppler (CD) flow has not previously been addressed in histologic evaluations of microvascular parameters. In this study, the authors attempted to define the differences between benign and malignant biopsy cores found in regions of the prostate with normal and high CD flow. METHODS Forty patients were retrospectively chosen for CD histologic comparison, each of whom had a core from a sextant biopsy with the following characteristics: malignant tissue with distinct increased CD flow (n = 11), malignant tissue with normal CD flow (n = 10), benign tissue with distinctly increased CD flow (n = 9), or benign tissue with normal CD flow (n = 10). All biopsy cores were stained with factor VIII-related antigen to identify microvasculature and to determine the number of microvessels per square millimeter (mm2) in an average cross-sectional area of microvessels, the percentage of tissue occupied by microvasculature, and the Gleason score. RESULTS In biopsies of benign tissue, high CD flow was associated with greater numbers (P < 0.025) of vessels of similar size than in normal flow benign biopsies. Biopsies of malignant tissue contained significantly greater numbers (P < 0.01) of much smaller vessels (P < 0.0005) than biopsies of benign tissue. In biopsies of malignant tissue, no significant differences in microvasculature parameters were noted between high and normal CD flow, yet biopsies with high CD flow had average Gleason score of 6.7 compared with only 5.9 for biopsies with normal CD flow (P < 0.025). CONCLUSIONS Increased CD flow in biopsies of benign tissue was correlated with a greater number of vessels/mm2, yet all biopsies of malignant tissue had more vessels/mm2 than those of benign tissue. Increased CD flow in biopsies of malignant tissue cannot be explained by standard microvasculature analysis but significantly guides biopsies to regions with a greater Gleason score. Cancer 1998;83:135-140. © 1998 American Cancer Society.
The disciplined use of simplifying assumptions

Simplifying assumptions --- everyone uses them but no one's programming tool explicitly supports them. In programming, as in other kinds of engineering design, simplifying assumptions are an important method for dealing with complexity. Given a complex programming problem, expert programmers typically choose simplifying assumptions which, though false, allow them to arrive rapidly at a program which addresses the important features of the problem without being distracted by all of its details. The simplifying assumptions are then incrementally retracted with corresponding modifications to the initial program. This methodology is particularly applicable to rapid prototyping because the main questions of interest can often be answered using only the initial program.Simplifying assumptions can easily be misused. In order to use them effectively two key issues must be addressed. First, simplifying assumptions should be chosen which simplify the design problem significantly without changing the essential character of the program which needs to be implemented. Second, the designer must keep track of all the assumptions he is making so that he can later retract them in an orderly manner. By explicitly dealing with these issues, a programming assistant system could directly support the use of simplifying assumptions as a disciplined part of the software development process.
Exchange Effects and CIDEP

We have presented a review of a number of different electron exchange interactions, which range from rieisenberg spin exchange to energy transfer. We have chosen to present most of this material largely from the perspective of esr experiments, but that is an arbitrary choice. One could build experiments around energy transfer or nmr experiments (or several other things!) and make nearly the same points. It is hoped that the reader will come away with the idea that all these exchange phenomena are related to each other, and that often the differences between their manifestations are usually remnants of the order of magnitude of the detailed observation, rather than fundamental differences.
Optimal finite-thrust spacecraft trajectories using collocation and nonlinear programming

A new method is described for the determination of optimal spacecraft trajectories in an inverse-square field using finite, fixed thrust. The method employs a recently developed direct optimization technique that uses a piecewise polynomial representation for the state and controls and collocation, thus converting the optimal control problem into a nonlinear programming problem, which is solved numerically. This technique has been modified to provide efficient handling of those portions of the trajectory that can be determined analytically, i.e., the coast arcs. Among the problems that have been solved using this method are optimal rendezvous and transfer (including multirevolution cases) and optimal multiburn orbit insertion from hyperbolic approach.
Impact of Antibiotic Resistance on the Treatment of Sepsis

Antibiotics are essential to the treatment of bacterial sepsis as they reduce the bacterial burden. The impact of bacterial resistance has recently been studied and found to be important in a range of conditions. Resistance to antibiotics can be defined genotypically, phenotypically and clinically through pharmacokinetic/pharmacodynamic studies and their correlations with clinical outcomes. Although the kinetics of antibiotics has been shown to be favourably altered in sepsis, a range of studies in sepsis has revealed that for most pathogens resistance contributes to significant increases in mortality. This has been clearly demonstrated in bacteraemia, including community- and hospital-acquired infection, and with bacteraemia caused by vancomycin-resistant enterococci, methicillin-resistant staphylococci and extended-spectrum producing Gram-negative bacteria. Significant mortality increases have also been seen with ventilator-associated pneumonia and serious infections requiring admission to intensive care. Gentotypic and phenotypic resistance in coagulase-negative staphylococci causing bacteraemia, and in invasive pneumococcal disease has not shown differences in mortality. In the latter case, dosage regimens have to date been adequate to overcome laboratory-defined resistance. Early indications are that de-escalating therapy from broad-spectrum initial coverage after results of cultures and susceptibility tests become available does not jeopardize outcomes, and further prospective studies are warranted. There is now convincing evidence that broad-spectrum initial therapy to cover the likely pathogens and their resistances pending culture results is mandatory in sepsis to minimize adverse outcomes.
Visual Exploration of Combined Architectural and Metric Information

We present MetricView, a software visualization and exploration tool that combines traditional UML diagram visualization with metric visualization in an effective way. MetricView is very easy and natural to use for software architects and developers yet offers a powerful set of mechanisms that allow fine customization of the visualizations for getting specific insights. We discuss several visual and architectural design choices which turned out to be important in the construction of MetricView, and illustrate our approach with several results using real-life datasets
Branes and fluxes in D=5 Calabi–Yau compactifications of M-theory

Abstract We discuss Poincare three-brane solutions in D =5 M-theory compactifications on Calabi–Yau (CY) threefolds with G -fluxes. We show that the vector moduli freeze at an attractor point. In the case with background flux only, the spacetime geometry contains a zero volume singularity with the three-brane and the CY space shrinking simultaneously to a point. This problem can be avoided by including explicit three-brane sources. We consider two cases in detail: a single brane and, when the transverse dimension is compactified on a circle, a pair of branes with opposite tensions.
Composite fermion valley polarization energies: Evidence for particle-hole asymmetry

In an ideal two-component two-dimensional electron system, particle-hole symmetry dictates that the fractional quantum Hall states around $\ensuremath{\nu}=1/2$ are equivalent to those around $\ensuremath{\nu}=3/2$. We demonstrate that composite fermions (CFs) around $\ensuremath{\nu}=1/2$ in AlAs possess a valley degree of freedom like their counterparts around $\ensuremath{\nu}=3/2$. However, focusing on $\ensuremath{\nu}=2/3$ and 4/3, we find that the energy needed to completely valley polarize the CFs around $\ensuremath{\nu}=1/2$ is considerably smaller than the corresponding value for CFs around $\ensuremath{\nu}=3/2$, thus betraying a particle-hole symmetry breaking.
Adaptation of the transfer function of the Hodgkin–Huxley (HH) neuronal model

Abstract The transfer functions of sensory neurons are known to adapt to the statistics of the input signals. It is however unclear whether such adaptation arises from the nonlinear dynamics of the neuron or emerges from the collective interaction among neurons embedded in a network. We investigated the Hodgkin–Huxley (HH) neuronal model's response to Gaussian white noise signals of different variances and found that the recovered kernel adapt its preferred temporal frequency and its energy gains according to noise variance. This adaptation is likely a consequence of the cooperative interaction between the noises and the bifurcation dynamics of the neurons.
A Direct, Continuous, Low-Power Catalytic Conversion of Methane to Higher Hydrocarbons via Microwave Plasmas

Abstract A selective, direct, continuous, low-power catalytic conversion of methane to higher energy hydrocarhons via microwave plasma methods has been developed in the pressure range 10 to 50 Torr. Methane can be converted to ethane, ethylene, and acetylene in different selectivities depending on the power of the plasma, flow rate, nature of the catalyst, and pressure in the system. Selectivities for ethane can be as high as 77%, for ethylene 25%, and for acetylene 25%. Conversions of methane as high as 52% have been realized. Coking can be minimized by proper choice of catalyst and high flow rates. Ethane and ethylene can be converted with 100% selectivity to ethylene and acetylene, respectively, in a similar process. Radicals are important in these transformations, with the catalyst surface providing sites for radical combination. Rates of reaction, energy balances, and mechanisms of reaction are discussed.
Active control of rotating stall in a low-speed axial compressor

The onset of rotating stall has been delayed in a low-speed, single-stage, axial research compressor using active feedback control. Control was implemented using a circumferential array of hot wires to sense propagating waves of axial velocity upstream of the compressor. Using this information, additional circumferentially traveling waves were then generated with appropriate phase and amplitude by «wiggling» inlet guide vanes driven by individual actuators. The control scheme considered the wave pattern in terms of the individual spatial Fourier components. A simple proportional control law was implemented for each harmonic. Control of the first spatial harmonic yielded an 11 percent decrease in the stalling mass flow, while control of the first, second, and third harmonics together reduced the stalling mass flow by 23 percent
Star Formation Histories of Early-Type Galaxies. I. Higher Order Balmer Lines as Age Indicators

We have obtained blue integrated spectra of 175 nearby early-type galaxies, covering a wide range in galaxy velocity dispersion and emphasizing those with ? < 100 km s-1. Galaxies have been observed both in the Virgo Cluster and in lower density environments. The main goals are the evaluation of higher order Balmer lines as age indicators and differences in stellar populations as a function of mass, environment, and morphology. In this first paper, our emphasis is on presenting the methods used to characterize the behavior of the Balmer lines through evolutionary population synthesis models. Lower ? galaxies exhibit a substantially greater intrinsic scatter, in a variety of line-strength indicators, than do higher ? galaxies, with the large intrinsic scatter setting in below a ? of 100 km s-1. Moreover, a greater contrast in scatter is present in the Balmer lines than in the lines of metal features. Evolutionary synthesis modeling of the observed spectral indexes indicates that the strong Balmer lines found primarily among the low-? galaxies are caused by young age, rather than by low metallicity. Thus we find a trend between the population age and the central velocity dispersion, such that low-? galaxies have younger luminosity-weighted mean ages. We have repeated this analysis using several different Balmer lines and find consistent results from one spectral indicator to another.
Vacuum Periodicity in a Yang-Mills Quantum Theory

We propose a description of the vacuum in Yang-Mills theory and arrive at a physical interpretation of the pseudoparticle solution and the attendant violation of symmetries. The existence of topologically inequivalent classical gauge fields gives rise to a family of quantum mechanical vacua, parametrized by a $\mathrm{CP}$-nonconserving angle. The requirement of vacuum stability against gauge transformations renders the vacua chirally noninvariant.
Multiparameter integrable QFT's with N bosons

Abstract We introduce a new family of integrable theories with N bosons and N freely adjustable mass parameters. These theories restrict in particular limits to the “generalized supersymmetric” sine-Gordon models, as well as to the flavor anisotropic chiral Gross Neveu models (studied recently by N. Andrei and collaborators). The scattering theory involves scalar particles that are no bound states, and bears an intriguing resemblance with the results of a sharp cut-off analysis of the Thirring model carried out by Korepin in 1980. Various physical applications are discussed. In particular, we demonstrate that our theories are the appropriate continuum limit of integrable quantum spin chains with mixtures of spins.