cssi/SciSciGPT-SciSciNet huggingface dataset:
Agricultural Industrialization: A Metaeconomics Look at the Metaphors by which we Live

Agriculture continues to be driven by rapid technological change on the base of a particular kind of value system. This path produces an abundance and variety of high-quality food and success for many. It also produces externalities, not the least of which is the sense of gloom among youth who might otherwise pursue food system careers. Perhaps we need to be carefully examining the values implicit within the invisible hand, subjecting it to scientific scrutiny. One alternative is a kind of metaeconomics that focuses on moral inquiry, recognizing both a self-interest and a joint others-interest in the outcomes.
Synchrony arising from a balanced synaptic plasticity in a network of heterogeneous neural oscillators

We investigate the dynamics of a recurrent network of coupled heterogeneous neural oscillators with experimentally observed spike-timing-dependent synaptic plasticity. We show both theoretically and by computer simulations that, in a regime of a balance between synaptic potentiation and depression, the network of such oscillators converges to a stable synchronous state. The stability of this state is fostered by flexible synaptic weights which adjust themselves based on the relative timing of firing of pre- and postsynaptic oscillators.
Constraints on Light Bottom Squarks from Radiative B-Meson Decays

The presence of a light {tilde b} squark (m{sub {tilde b}} {approx} 4 GeV) and gluino (m{sub {tilde g}} {approx} 15 GeV) might explain the observed excess in b-quark production at the Tevatron. Though provocative, this model is not excluded by present data. The light supersymmetric particles can induce large flavor-changing effects in radiative decays of B mesons. We analyze the decays B {yields} X{sub s}{gamma} and B {yields} X{sub sg} in this scenario and derive restrictive bounds on the flavor-changing quark-squark-gluino couplings.
Effects of Broadband Laser Generated Ultrasound on Array Gain

Array gain is a common parameter used in laser phased array research. This paper will present a new parameter called the frequency modulation of laser phased array (FMLPA). The array gain model for laser phased arrays was derived using an assumption that ultrasound from each array member interferes with each other. This would be always true if laser generated ultrasound is narrow band. However, laser generation of ultrasound is broad band. Broad band ultrasound signals have short duration in the time domain. If the time delay between generated wave fronts from each array member is longer than the duration of the broad band ultrasound signal from each array member, the ultrasound signals from each array member will not interfere with each other. The time delay between generated wave fronts from each array member is 0 s at a laser phased array’s beam steering angle and increases away from the beam steering angle. Therefore, ultrasound from each array member always interfere at angles close to the beam steering angle. However, ultrasound from each array member may not interfere at angles away from the beam steering angle depending on the time delay between generated wave fronts and duration of the broad band ultrasound signal. A theoretical model of the FMLPA was developed and experimentally verified for use when ultrasound from each array member does not interfere with each other. It was experimentally verified that current array gain equations still apply when ultrasound from array members interfere with each other. The FMLPA can be used to create new techniques for measuring weld penetration depth, crack location, and dimensions of objects.
Threshold voltage shifts in narrow-width SOI devices due to quantum mechanical size-quantization effects

Abstract We have investigated the impact of quantum mechanical space-quantization effects on the operation of a narrow-width SOI device structure. The presence of a two-dimensional carrier confinement gives rise to larger average displacement of the carriers from the interface proper and lower sheet electron density in the channel region. This, in turn, results not only in a significant increase in the threshold voltage but also in its pronounced channel width dependency. In this work, we have used classical 3D Monte Carlo particle-based simulations. Quantum mechanical space-quantization effects have been accounted for via an effective potential scheme that has been quite successful in describing bandgap widening effect and charge set back from the interface.
Chronic ulcerative colitis associated with malignant disease

The term "chronic ulcerative colitis" has come to mean a definite disease entity, which presents characteristic clinical, pahologic, proctoscopic and roentgenologic data. Clinically, the disease is characterized by frequent rectal discharges of mucus, blood and pus; the presence of diarrhea depends on the extent of involvement of the colon and the severity of the disease. Usually the infection begins in the rectum and spreads upward, and frequently affects the entire colon. If, therefore, the lesions involve only the rectum and rectosigmoid, the stools may be scybalous and the patient may complain of constipation, while having twelve or more bloody, purulent rectal emissions daily. The result of the long-continued passage of blood and the toxemia from the severely infected colon is general wasting, anemia, emaciation and, eventually, chronic invalidism. Obviously the symptoms of this disease may be readily confused with other conditions in which mucus, blood and sometimes pus are discharged
Microsurgical fertilization: world survey 1993

Micromanipulation of gametes is not a new field. The early report by Tyler and Monroy (1953) described the difficulty of penetrating the egg membrane with a micropipette. Further experimental studies were designed to clarify mechanisms of fertilization by three main techniques and in various models: (a) injecting hamster sperm directly into the cytoplasm of hamster oocytes (Uehara and Yanagimachi, 1976; Lanzendorf et al, 1988), and mouse sperm into cytochalasin-treated mouse oocytes (Market, 1983); (b) subzonal insemination (SUZI) in mouse oocytes (Barg et al, 1986; Laws-King et al, 1987; Mann, 1988); and (c) breaching the zona pellucida by acid digestion using Tyrode's solution (Gordon and Talansky, 1986) by mechanical means (Malter and Cohen, 1989) or with laser beams (Tadir et al, 1989) to provide an opening through which sperm can gain access to the egg (Figure 1). The move of microsurgical fertilization from basic studies to clinical practice was an expected consequence in view of the low fertilization rate following conventional insemination in vitro in patients with severe malefactor infertility. Preliminary reports on human pregnancy following various kinds of microsurgical fertilization procedures (Ng et al, 1988; Malter and Cohen, 1989; Fishel et al, 1990a) stimulated the clinical use of these procedures for patients who have failed to achieve fertilization in repeated IVF attempts, or for those with sperm quality that does not meet minimal criteria for IVF. However, the lack of clear definitions for male-factor versus severe male-factor infertility (see Chapter 4), and the multivariable nature of sperm malfunction leading to microsurgical fertilization, creates objective difficulties in patient selection and interpretation of the outcome. The first world survey on microsurgical fertilization from 21 different programmes was published in 1991 (Cohen, 1991; see Chapter 4). In this review, 69 clinical pregnancies following partial zona dissection (PZD) (53 babies born) and 59 pregnancies following SUZI (11 babies born) were documented. Although special attention has been devoted in this survey to sperm quality, it was difficult to draw predictive conclusions to guide patient selection. Several recent studies using sibling oocytes supported the recommendation that SUZI and PZD should be practised jointly to improve the overall pregnancy rate (Fishel et al 1990b; Cohen et al, 1992; Tadir et al, 1992). A recent report on improved fertilization and pregnancy rates following intracytoplasmatic sperm injection (ICSI) because of poor sperm quality is encouraging and induced a new wave of optimism (Palermo et al, 1993).
Treatment of deep vein thrombosis with enoxaparin in pediatric cancer patients receiving chemotherapy.

There are few data regarding the use of enoxaparin in children undergoing myelosuppressive therapy for malignancies even though thrombosis is a known risk in pediatric patients with malignancies. Low-molecular-weight heparin such as enoxaparin has become widely used in adult patients with thrombosis. The purpose of this study was to review the utilization of low-molecular-weight heparin, enoxaparin (Lovenox), in children with cancer at our institution who had thrombosis while undergoing myelosuppressive chemotherapy. In particular we were interested in the efficacy of enoxaparin in these patients, and in whether these children were able to continue their chemotherapy without adjustment or interruption secondary to bleeding complications. We conducted a retrospective review from 1999 through April 1, 2004. Seven patients (4—17 years of age) were identified. Diagnosis included B-precursor acute lymphoblastic leukemia (ALL) (n=three), T-ALL, Hodgkin's disease, anaplastic large cell lymphoma, and rhabdomyosar...
Information rates for multiantenna systems with unknown fading

This talk presents analytical upper and lower bounds on the information rate of a multiuser Rayleigh fading channel with no channel state information (CSI) at the transmitters or the receivers. These bounds are shown to converge whenever an individual userpsilas data rate is small compared with the bandwidth, e.g., when users can employ CDMA. The amount of spreading required for a given degree of convergence depends on the number of receive antennas; however, the number of users can be sufficient for the aggregate spectral density to be large. The talk presents exact analytical expressions for the information rates of both the block fading and the continuous correlated fading channel models in this regime and presents techniques for extending these to more general channel models.
Bridge jobs: A comparison across cohorts

Are today's retirees following in the footsteps of their older peers with respect to gradual retirement? Recent evidence from the Health and Retirement Study (HRS) suggests that most older American...
Total synthesis of lysobactin.

Antibiotic resistance has become a significant public health concern. Antibiotics that belong to new structural classes and manifest their biological activity via novel mechanisms are urgently needed. Lysobactin, a depsipeptide antibiotic has displayed very strong antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA) as well as vancomycin-resistant enterococci (VRE) with minimum inhibitory concentrations (MICs) ranging from 0.39 to 0.78 μg/mL. The MIC values against VRE were more than 50-fold lower than those reported for vancomycin itself. Lysobactin was found to inhibit nascent peptidoglycan formation; however, this activity was not antagonized in the presence of N-acyl-l-Lys-d-Ala-d-Ala, the binding domain on the cell wall precursors that is utilized by vancomycin. Thus, lysobactin represents a promising agent for the treatment bacterial infections due to resistant pathogens. We describe a convergent synthesis of lysobactin that relies upon a highly efficient macrocyclizatio...
Workspace evaluation of Stewart platforms

The workspace and the dexterity of a Stewart platform are affected by the choice of its major dimensions, actuator stroke and the kinematic constraints of its joints. An investigation of the effects of these parameters on workspace volume of the platform is presented. The obtained results were normalized so that they could be used as a design tool for the selection of dimensions, joints and actuators.
Atmosphere behavior in gas-closed mouse-algal systems: An experimental and modelling study

A NASA-sponsored research program initiated using mathematical modelling and laboratory experimentation aimed at examining the gas-exchange characteristics of artificial animal/plant systems closed to the ambient atmosphere is studied. The development of control techniques and management strategies for maintaining the atmospheric levels of carbon dioxide and oxygen at physiological levels is considered. A mathematical model simulating the behavior of a gas-closed mouse-algal system under varying environmental conditions is described. To verify and validate the model simulations, an analytical system with which algal growth and gas exchange characteristics can be manipulated and measured is designed, fabricated, and tested. The preliminary results are presented.
Probabilistic approach to the length-scale dependence of the effect of water hydrogen bonding on hydrophobic hydration

We present a probabilistic approach to water–water hydrogen bonding that allows one to obtain an analytic expression for the number of bonds per water molecule as a function of both its distance to a hydrophobic particle and hydrophobe radius. This approach can be used in density functional theory (DFT) and computer simulations to examine particle size effects on the hydration of particles and on their solvent-mediated interaction. For example, it allows one to explicitly identify a water hydrogen bond contribution to the external potential, whereto a water molecule is subjected near a hydrophobe. The DFT implementation of the model predicts the hydration free energy per unit area of a spherical hydrophobe to be sharply sensitive to the hydrophobe radius for small radii and weakly sensitive thereto for large ones; this corroborates the vision of the hydration of small and large length-scale particles as occurring via different mechanisms. On the other hand, the model predicts that the hydration of even ap...
Parsing reflective grammars

Existing technology can parse arbitrary context-free grammars, but only a single, static grammar per input. In order to support more powerful syntax-extension systems, we propose reflective grammars, which can modify their own syntax during parsing. We demonstrate and prove the correctness of an algorithm for parsing reflective grammars. The algorithm is based on Earley's algorithm, and we prove that it performs asymptotically no worse than Earley's algorithm on ordinary context-free grammars.
Quiver theories from D6 branes via mirror symmetry

We study = 1 four dimensional quiver theories arising on the worldvolume of D3-branes at del Pezzo singularities of Calabi-Yau threefolds. We argue that under local mirror symmetry D3-branes become D6-branes wrapped on a three torus in the mirror manifold. The type-IIB (p,q) 5-brane web description of the local del Pezzo, being closely related to the geometry of its mirror manifold, encodes the geometry of 3-cycles and is used to obtain gauge groups, quiver diagrams and the charges of the fractional branes.
Government Accounting: An Assessment of Theory, Purposes and Standards

Government accounting and financial reporting aims to protect and manage public money and discharge accountability. These purposes, and the nature of public goods and tax financing, give rise to differences with commercial accounting. This is not yet reflected either in government accounting standards in English-speaking developed nations or in international public sector accounting standards. All of these are heavily influenced by private sector practices, which favour the accrual basis and consolidated reporting. This article argues for a gradual symmetric approach to accruals and a combination of government-wide and fund reporting. The author also proposes some broad accounting principles to promote political and economic accountability.
Investigations of monolayers by fluorescence microscopy

The technique of fluorescence microscopy enables imaging of coexisting domains in Langmuir monolayers which have been doped with a small amount of a fluorescent probe. It is also possible to image surface aggregates formed by labeled proteins interacting with phosholipid monolayers. The method has provided information concerning phase behavior and structure of monolayers and proven useful in the study of monolayers as model systems of membrance processes. © 1994 Wiley-Liss, Inc.
PAIRING OF STRONGLY CORRELATED NUCLEONS

Pairing properties of infinite matter are surveyed that are obtained from self-consistent Green's function calculations. A complete treatment of off-shell propagation that incorporates the effects of short-range correlations is included. Mean-field calculations based on the BCS approach are superseded by the present results, which resolve a long-standing puzzle associated with 3S1-3D1 (proton-neutron) pairing in symmetric nuclear matter. Results for 1S0 pairing in pure neutron matter are in agreement with recent Monte-Carlo calculations for this system. The possibility of proton pairing in finite nuclei, as a result of increasing proton correlations with increasing nucleon asymmetry, is pointed out.
Experimental Evaluation of a Metal Mesh Bearing Damper

Metal mesh is a commercially available material used in many applications including seals, heat shields, filters, gaskets, aircraft engine mounts, and vibration absorbers. This material has been tested by the authors as a bearing damper in a rotordynamic test rig. The test facility was originally used to support the design of a turboprop engine, developing squirrel cages and squeeze film dampers for both the gas generator and power turbine rotors. To design the metal mesh damper, static stiffness and dynamic rap test measurements were first made on metal mesh samples in a specially designed nonrotating test fixture, These property tests were performed on samples of various densities and press fits. One sample was also tested in an Instron machine as an ancillary and redundant way to determine the stiffness. Using the stiffness test results and equations derived by a previous investigator, a spreadsheet program was written and used to size metal mesh donuts that have the radial stiffness value required to replace the squirrel cage in the power turbine. The squirrel cage and squeeze film bearing damper developed for the power turbine rotor was then replaced by a metal mesh donut sized by the computer code. Coast down tests were conducted through the first critical speed of the power turbine. The results of the metal mesh tests are compared with those obtained from previous testing with the squeeze film damper and show that the metal mesh damper has the same damping as the squeeze film at room temperature but does not lose its damping at elevated temperatures up to 103°C. Experiments were run under several different conditions, including balanced rotor, unbalanced rotor, heated metal mesh, and wet (with oil) metal mesh. The creep, or sag, of the metal mesh supporting the rotor weight was also measured over a period of several weeks and found to be very small. Based on these tests, metal mesh dampers appear to be a viable and attractive substitute for squeeze film dampers in gas turbine engines. The advantages shown by these tests include less variation of damping with temperature, ability to handle large rotor unbalance, and the ability (if required) to operate effectively in an oil free environment. Additional testing is required to determine the endurance properties, the effect of high impact or maneuver loads, and the ability to sustain blade loss loads (which squeeze films cannot handle).
Asset sales and increase in focus

Abstract We find that asset sales lead to an improvement in the operating performance of the seller's remaining assets in each of the three years following the asset sale. The improvement in performance occurs primarily in firms that increase their focus; this change in operating performance is positively related to the seller's stock return at the divestiture announcement. The announcement stock returns are also greater for focus-increasing divestitures. Further, we find evidence that some of the seller's gains result from a better fit between the divested asset and the buyer.
Infrared spectra and structures of the coinage metal dihydroxide molecules.

Laser-ablated Cu, Ag, and Au atoms react with H2O2 and with H2 + O2 molecules during condensation in excess argon to give four new IR absorptions in each system (O−H stretch, M−O−H bend, O−M−O stretch, and M−O−H deformation modes) that are due to the coinage metal M(OH)2 dihydroxide molecules. Isotopic substitution (D2O2, 18O2, 16O18O, D2, and HD) and comparison with frequencies computed by DFT verify these assignments. The calculations converge to 2Bg ground electronic state structures with C2h symmetry, 111−117° M−O−H bond angles, and substantial covalent character for these new metal dihydroxide molecules, particularly for Au(OH)2. This is probably due to the high electron affinity of gold owing to the effect of relativity.
On the estimation of the heavy-tail exponent in time series using the max-spectrum

This paper addresses the problem of estimating the tail index α of distributions with heavy, Pareto-type tails for dependent data, that is of interest in the areas of finance, insurance, environmental monitoring and teletraffic analysis. A novel approach based on the max self-similarity scaling behavior of block maxima is introduced. The method exploits the increasing lack of dependence of maxima over large size blocks, which proves useful for time series data. We establish the consistency and asymptotic normality of the proposed max-spectrum estimator for a large class of m-dependent time series, in the regime of intermediate block-maxima. In the regime of large block-maxima, we demonstrate the distributional consistency of the estimator for a broad range of time series models including linear processes. The max-spectrum estimator is a robust and computationally efficient tool, which provides a novel time-scale perspective to the estimation of the tail exponents. Its performance is illustrated over synthetic and real data sets. Copyright © 2009 John Wiley & Sons, Ltd.
A model for the genesis of arterial pressure Mayer waves from heart rate and sympathetic activity

Both theoretic models and cross-spectral analyses suggest that an oscillating sympathetic nervous outflow generates the low-frequency arterial pressure fluctuations termed Mayer waves. Fluctuations in heart rate also have been suggested to relate closely to Mayer waves, but empiric models have not assessed the joint causative influences of heart rate and sympathetic activity. Therefore, we constructed a model based simply upon the hemodynamic equation derived from Ohm's Law. With this model, we determined time relations and relative contributions of heart rate and sympathetic activity to the genesis of arterial pressure Mayer waves. We assessed data from eight healthy young volunteers in the basal state and in a high sympathetic state known to produce concurrent increases in sympathetic nervous outflow and Mayer wave amplitude. We fit the Mayer waves (0.05-0.20 Hz) in mean arterial pressure by the weighted sum of leading oscillations in heart rate and sympathetic nerve activity. This model of our data showed heart rate oscillations leading by 2-3.75 s were responsible for almost half of the variance in arterial pressure (basal R2 = 0.435 +/- 0.140, high sympathetic R2= 0.438 +/- 0.180). Surprisingly, sympathetic activity (lead 0-5 s) contributed only modestly to the explained variance in Mayer waves during either sympathetic state (basal: delta R2 = 0.046 +/- 0.026; heightened: delta R2 = 0.085 +/- 0.036). Thus, it appears that heart rate oscillations contribute to Mayer waves in a simple linear fashion, whereas sympathetic fluctuations contribute little to Mayer waves in this way. Although these results do not exclude an important vascular sympathetic role, they do suggest that additional factors, such as sympathetic transduction into vascular resistance, modulate its influence.
A Radial Basis Function (RBF)-Finite Difference (FD) Method for Diffusion and Reaction---Diffusion Equations on Surfaces

In this paper, we present a method based on radial basis function (RBF)-generated finite differences (FD) for numerically solving diffusion and reaction---diffusion equations (PDEs) on closed surfaces embedded in $${\mathbb {R}}^d$$Rd. Our method uses a method-of-lines formulation, in which surface derivatives that appear in the PDEs are approximated locally using RBF interpolation. The method requires only scattered nodes representing the surface and normal vectors at those scattered nodes. All computations use only extrinsic coordinates, thereby avoiding coordinate distortions and singularities. We also present an optimization procedure that allows for the stabilization of the discrete differential operators generated by our RBF-FD method by selecting shape parameters for each stencil that correspond to a global target condition number. We show the convergence of our method on two surfaces for different stencil sizes, and present applications to nonlinear PDEs simulated both on implicit/parametric surfaces and more general surfaces represented by point clouds.
The art and science of interstellar message composition: a report on international workshops to encourage multidisciplinary discussion

Abstract Throughout the history of the Search for Extraterrestrial Intelligence (SETI), there has been widespread recognition of the profound societal implications of detecting intelligence beyond Earth. At the SETI Institute, interstellar message construction serves as the focus of a multidisciplinary attempt to prepare for the cultural impact of signal detection and the critical events that would follow. Interstellar message construction at the SETI Institute builds upon the recommendations of the 1991–1992 Workshops on the Cultural Aspects of SETI, while also exploring opportunities for multidisciplinary contributions on new topics. Through a series of international workshops in Toulouse, Paris, Zagreb, Washington, and Bremen, the SETI Institute and partner organizations have fostered broad-based discussion about some of the most important decisions that would follow detection of extraterrestrial intelligence, including “should we reply?” and if so, “what should we say, and how might we say it?”. Several of the themes addressed at these workshops will be highlighted, including the relationship between art and science in designing messages, the value of interactive messages, and the importance of better understanding the nature of language.
Rayleigh–Taylor problem for a liquid–liquid phase interface

A linear stability analysis of the Rayleigh–Taylor problem for an incompressible fluid undergoing a liquid–liquid phase transformation is presented. Both inviscid and linearly viscous fluids are considered and interfacial tension is taken into account. Instability is possible only when the phase with the higher density is above that with the lower density. Study of the inviscid case shows that the exchange of mass between the phases decreases significantly both the range of unstable wavenumbers and the maximum growth rate for unstable perturbations as compared to those arising classically. For a linearly viscous fluid, the shear and dilational viscosities of the interface are taken into account as are the migrational viscosities associated with the motion of the interface relative to the underlying fluid. When no mass exchange occurs between the phases in the base state and the interfacial viscosities are neglected, the growth rates exceed by at least an order of magnitude those for the classical Rayleigh–Taylor problem. The various interfacial viscosities slow the growth rates of disturbances, but do not influence the range of unstable wavenumbers. For both the inviscid and viscous cases, interfacial tension plays the same stabilizing role as it does classically.
Concise synthesis of taxol a-ring components: Remote diastereoselective additions of alkenyl lithiums to aldehydes

Abstract The acid chloride 6 provides access to 7 (R,S and S,S) which upon bromine-lithium exchange undergoes remarkably highly diastereoselective additions to aldehydes; 7 is also readily elaborated into the acctal 10.
Bumpy Spin-Down of Anomalous X-Ray Pulsars: The Link with Magnetars

The two anomalous X-ray pulsars (AXPs) with well-sampled timing histories, 1E 1048.1-5937 and 1E 2259+586, are known to spin down irregularly, with "bumps" superposed on an overall linear trend. Here we show that if AXPs are nonaccreting magnetars, i.e., isolated neutron stars with surface magnetic fields B0 1010 T, then they spin down electromagnetically in exactly the manner observed, because of an effect called "radiative precession." Internal hydromagnetic stresses deform the star, creating a fractional difference = (I3 - I1)/I1 ~ 10-8 between the principal moments of inertia I1 and I3; the resulting Eulerian precession couples to an oscillating component of the electromagnetic torque associated with the near-zone radiation fields, and the star executes an anharmonic wobble with period τpr ~ 2π/Ω(t) ~ 10 yr, where Ω(t) is the rotation frequency as a function of time t. We solve Euler's equations for a biaxial magnet rotating in vacuo, show that the computed Ω(t) matches the measured timing histories of 1E 1048.1-5937 and 1E 2259+586, predict Ω(t) for the next 20 years for both objects, predict a statistical relation between dΩ/dt and τpr, to be tested as the population of known AXPs grows, and hypothesize that radiative precession will be observed in future X-ray timing of soft gamma-ray repeaters.
Threefold flops via matrix factorization

The structure of birational maps between algebraic varieties becomes increasingly complicated as the dimension of the varieties increases. There is no birational geometry to speak of in dimension one: if two complete algebraic curves are birationally isomorphic then they are biregularly isomorphic. In dimension two we encounter the phenomenon of the blowup of a point, and every birational isomorphism can be factored into a sequence of blowups and blowdowns. In dimension three, however, we first encounter birational maps which are biregular outside of a subvariety of codimension two (called the center of the birational map). When the center has a neighborhood with trivial canonical bundle, the birational map is called a flop. The focus of this paper will be the case of a three-dimensional simple flop, in which the center is an irreducible curve (necessarily a smooth rational curve). One of the motivations for studying this case is a theorem of Kawamata [17], which says that all birational maps between Calabi–Yau threefolds can be expressed as the composition of simple flops (in fact, of simple flops between nonsingular varieties). Important examples of simple flops were provided by Laufer [22], and three-dimensional simple flops were studied in general by Reid [25] and by Pinkham [24]. One fundamental property is that the center of the flop can be contracted, leaving a (singular) variety X which is dominated by both of the varieties involved in the original flop. X has a hypersurface singularity, and thus can be locally described as {f = 0} for some polynomial f in which
Invertase inhibitor in tomato fruit

Abstract A protein that inhibits invertase has been purified from tomato fruit. The purification procedure involved extraction of tomato tissue at pH 1.6 to inactivate most of the invertase. The remaining invertase was removed by chromatography on DEAE-Sephadex A-50 at pH 6.5. The inhibitor was then purified by chromatography on Sephadex G-75, Mono S and Mono P columns. It is a heat stable protein with a Mr of 18 000 as determined by gel filtration. The reactivity of the inhibitor with tomato invertase was dependent on the pH of the reaction mixture, with maximum inhibition at pH 5. Inhibition decreased as the pH was raised or lowered, resulting in double pH optima for the residual invertase activity. The tomato inhibitor also inhibited the invertase from potato tubers but not salivary amylase and various proteases.
Industry Specialization by Auditors

Dramatic changes in recent years in the audit market suggest the timeliness of an investigation of trends in auditor concentration and an extension of prior research (e.g., Danos and Eichenseher 1982). In recent press, large audit firms have claimed that specialization is a goal of increasing importance. Peat Marwick, for example, has restructured along industry lines, claiming to be recruiting professionals for national teams of multidisciplinary experts organized to “focus on the same industry to serve clients optimally.” On the other hand, litigation concerns might prompt auditors to diversify their risks by diversifying their clientele. In this study, we examine trends in industry specialization from 1976 to 1993 and the industry factors which may affect specialization; whether market share increases are greater for audit firms classified as specialists; and whether the nation's largest audit firms have increased their market share in the industries which they have identified as their focus industries...
An approach to teaching documents courses

Abstract This article discusses three class projects used in one-semester documents courses and drawing upon the resources of Federal depository libraries. It also encourages more treatment of documents education in the literature of librarianship.
Context-free grammar forms

In an attempt to provide a unified theory of grammars, a model is introduced which has two components. The first is a ''grammar form,'' which provides the general structure of the productions in the grammars to be defined. The second is an ''interpretation'', which yields a specific grammar. By considering all interpretations, a family of grammars, intimately related to that of the grammar form, is obtained. Many of the well-known families of grammars occur as special instances. Attention is focused on the situation when the productions in the grammar form are context free. Necessary and sufficient conditions on a context-free grammar form are given in order for it, to yield, respectively, exactly the finite languages, the regular sets, the linear context-free languages, and all the context-free languages. Each context-free grammar form can be replaced by another, yielding the same family of languages, in which the underlying grammar is sequential. Of special interest to language theory is the fact the family of languages obtained from each context-free grammar form is a full principal semi-AFL.
Radial weak solutions for the Perona–Malik equation as a differential inclusion

Abstract The Perona–Malik equation is an ill-posed forward–backward parabolic equation with some application in image processing. In this paper, we study the Perona–Malik type equation on a ball in an arbitrary dimension n and show that there exist infinitely many radial weak solutions to the homogeneous Neumann boundary problem for smooth nonconstant radially symmetric initial data. Our approach is to reformulate the n-dimensional equation into a one-dimensional equation, to convert the one-dimensional problem into an inhomogeneous partial differential inclusion problem, and to apply a Baire's category method to the differential inclusion to generate infinitely many solutions.
Can Giant Planets Form by Direct Gravitational Instability

Gravitational instability has been invoked as a possible mechanism of the giant planet production in protoplanetary disks. Here we critically revise its viability by noting that to form planets directly, it is not enough for protoplanetary disks to be gravitationally unstable. They must also be able to cool efficiently (on a timescale comparable to the local disk orbital period) to allow the formation of the bound clumps by fragmentation. A combination of the dynamical and thermal constraints puts very stringent lower limits on the properties of disks capable of fragmenting into the self-gravitating objects: for the gravitational instability to form giant planets at 10 AU in the disk cooled by the radiation transfer, the gas temperature must exceed 103 K with a minimum disk mass of 0.7 M☉ and a luminosity of 40 L☉. Although these requirements are relaxed in the more distant parts of the disk, masses of the bound objects formed as a result of instability are too large even at 100 AU (~10MJ) to explain the characteristics of known extrasolar giant planets. Such protoplanetary disks (and planets formed in them) have very unusual observational properties, and this severely constrains the possibility of giant planet formation by direct gravitational instability.
Parameterized Cancellation of Partial-Band Partial-Block-Duration Interference for Underwater Acoustic OFDM

Despite that underwater acoustic channels are well known to contain various interferences, research on interference mitigation in underwater acoustic communications has been very limited. In this paper, we deal with a wideband orthogonal frequency division multiplexing (OFDM) transmission in the presence of an external interference which occupies partially the signal band and whose time duration is shorter than the OFDM block. We parameterize the unknown interference waveform by a number of parameters assuming prior knowledge of the frequency band and time duration of the interference, and develop an iterative receiver, which couples interference detection via a generalized likelihood-ratio-test (GLRT), interference reconstruction and cancellation, channel estimation, and data detection. In addition to simulation results, we verify the receiver performance using data sets collected from two experiments. In both time-invariant and time-varying channels, the proposed iterative receiver achieves robust performance in the presence of unknown interference.
Leveraging Information Across Categories

Companies are collecting increasing amounts of information about their customers. This effort is based on the assumption that more information is better and that this information can be leveraged to predict customers' behavior in a variety of situations and product categories. For example, information about a customer's purchase behavior in one category can be helpful in predicting his potential behavior in a related category, which in turn could help a firm in its cross-selling efforts. In this paper, we present a model to better understand and predict a consumer's purchases and preferences when we may have limited or no information about him in one or more product categories. Conceptually this involves leveraging information from purchases of other consumers in multiple categories as well as partial information (e.g., purchase in one of the categories) of the target consumer. Our approach builds on the pioneering work of (Rossi et al. (1996)) who demonstrate the value of purchase information in the context of a single product category. We present results from an extensive simulation as well as an application on scanner panel data. Our simulation shows many interesting and somewhat surprising results. Specifically, we find that compared to a single-category analysis, a cross-category analysis does not lead to any significant improvement in data likelihood in most cases. Therefore, the single-category analysis of (Rossi et al. (1996)) is even more powerful than previously thought. However, we also find that a cross-category analysis does improve parameter recovery in many situations as compared to a single-category analysis. It is in these conditions that retailers can use cross-category information to better implement micro marketing programs. We demonstrate the transfer of information across categories in an application of two grocery products—Breakfast Foods and Table Syrup. In spite of a reasonable correlation (0.21) in the price parameter across these two categories, our simulation guidelines predict very little benefit of cross-category analysis over single-category analysis. Our empirical results confirm this prediction.
Environmental Risk Management for Developing Countries

Disaster losses in the developing world have increased substantially over the past decade and are likely to accelerate in future years. This paper proposes an environmental risk management program for developing countries that consists of six modules. The pre-disaster phase includes risk identification, risk mitigation, risk transfer, and preparedness; the post-disaster phase is devoted to emergency response and rehabilitation and reconstruction. We illustrate the elements of each of these phases with a set of examples and then show how they have been applied in three countries: Fiji, India,and Turkey. The paper concludes with a set of suggestions for future research.
Increased antiviral activity of cyclic urea HIV protease inhibitors by modifying the P1/P1' substituents

A series of alkyl substituted P1/P1' analogs was prepared in an attempt to increase translation of the 3-aminoindazole class of HIV protease inhibitors. Increasing the lipophilicity of the P1/P1' residues dramatically improved translation of enzyme activity to antiviral activity in the whole cell assay.
Small cell lung cancer antigen expression differs on ‘classic’ and ‘variant’ SCLC and carcinoid cells

Abstract The panel of 98 monoclonal antibodies (MOABS) (mouse or rat) provided by the Second International Workshop on Small Cell Lung Cancer Antigens was tested by indirect immunofluorescence and flow cytometry using prototype cell lines [NCI-H69 (SCLC ‘classic’), NCI-N417 (SCLC ‘variant’), NCI-H727 (carcinoid) (A.F. Gazdar et al., Bethesda, MD)] as well as normal human peripheral blood lymphocytes (PBL) and sea urchin coelomocytes [Koros, A.M.C., Int. J. Neurosci. 48:161 (1989)]. All cells had some reactivity with some of the MOABS. There is, however, differential expression of antigens amongst the prototype cell lines which may provide a useful method for phenotyping human lung cancers.
On the Extreme-Ultraviolet Emission from Galaxy Clusters

An extremely soft X-ray excess throughout galaxy clusters has been claimed as a new feature of these systems, with important physical implications. We have reexamined this feature in the five clusters for which it has been discussed, using the most recent X-ray absorption cross sections, X-ray data processing techniques, and a consistent set of H I data. For the Virgo cluster, we find that the spectrum can be fitted with a single-temperature thermal plasma and an X-ray absorption column that is not significantly different than the Galactic H I column. The results for Abell 1367, Abell 1656 (Coma), Abell 1795, and Abell 2199 are similar in that the difference between the X-ray absorption column and the Galactic H I column is less than 3 σ for He/H=0.09, and for He/H=0.10 only one cluster location leads to a Galactic H I column more than 3 σ above the X-ray absorption column (Coma, with one location with a 3.6 σ difference). We conclude that there is no strong evidence for the extremely soft X-ray excess in galaxy clusters.
Exact spectra of conformal supersymmetric nonlinear sigma models in two dimensions

Abstract We study two-dimensional nonlinear sigma models in which the target spaces are the coset supermanifolds U (n+m|n)/[ U (1)× U (n+m−1|n)]≅ CP n+m−1|n (projective superspaces) and OSp(2n+m|2n)/OSp(2n+m−1|2n)≅S2n+m−1|2n (superspheres), n, m integers, −2⩽m⩽2; these quantum field theories live in Hilbert spaces with indefinite inner products. These theories possess non-trivial conformally-invariant renormalization-group fixed points, or in some cases, lines of fixed points. Some of the conformal fixed-point theories can also be obtained within Landau–Ginzburg theories. We obtain the complete spectra (with multiplicities) of exact conformal weights of states (or corresponding local operators) in the isolated fixed-point conformal field theories, and at one special point on each of the lines of fixed points. Although the conformal weights are rational, the conformal field theories are not, and (with one exception) do not contain the affine versions of their superalgebras in their chiral algebras. The method involves lattice models that represent the strong-coupling region, which can be mapped to loop models, and then to a Coulomb gas with modified boundary conditions. The results apply to percolation, dilute and dense polymers, and other statistical mechanics models, and also to the spin quantum Hall transition in non-interacting fermions with quenched disorder.
The role of glucagon administration in the diagnosis and treatment of patients with tumor hypoglycemia.

BACKGROUND Tumor hypoglycemia can be recurrent and severe enough to interfere with definitive antineoplastic treatment. Therefore, rapid commencement of effective therapy is essential. This is best accomplished by identifying which of the hypoglycemic processes is involved, as treatments differ. Some patients present with hypoglycemia and liver metastases; among them, only a few develop hypoglycemia as a result of a failure of hepatic glucose production. Most develop hypoglycemia as a result of an insulin-mediated process-either the secretion of insulin by an islet-cell tumor or the secretion of insulin-like growth factor-II by an extrapancreatic tumor. Administration of glucagon can rapidly make the two groups distinguishable, thus allowing institution of therapy and prompt symptomatic control of hypoglycemia. METHODS The charts of seven patients with tumor hypoglycemia and liver metastases who had a glucagon stimulation test (serial glucose measurements after a 1 mg infusion of glucagon) as part of the workup for hypoglycemia were retrospectively reviewed. Those patients whose test revealed a rise in serum glucose of >30 mg/dL were subsequently treated as outpatients, with a continuous glucagon infusion delivered by a portable pump. RESULTS Three patients had an insulinoma and four had non-islet cell tumor hypoglycemia (NICTH) due to hepatocellular carcinoma, colon carcinoma, meningeal sarcoma, and hemangiopericytoma, respectively. All of the patients had liver metastateses. Evaluation of these patients included a glucagon stimulation test (1 mg intravenous push), which quickly provided information about the mechanism of tumor hypoglycemia and the direction towards therapy. All patients with insulinoma responded to glucagon with a rise in blood serum glucose levels, indicating adequate glycogen stores. The four patients with NICTH had mixed responses: in two patients, the response suggested that hypoglycemia was due to an insulin-like tumor product; glucose levels did not rise in the other two cases, indicating that hypoglycemia was due to poor hepatic glycogen reserve/liver failure. In all cases, a glycemic response to glucagon predicted good response to long term treatment with glucagon (0.06-0.3 mg/hour, via intravenous infusion pump). CONCLUSIONS The glucagon stimulation test is a simple and fast approach that serves to clarify the etiology of hypoglycemia (diagnostic use) and guide effective long term strategies for its control (therapeutic use) in patients with neoplastic diseases and liver metastases. Cancer 1998; 82:1585-92. © 1998 American Cancer Society.
Color and constitution. Part 8 . Some novel dyestuffs containing indoxyl residues

Novel dyes containing C-likned indoxyl residues are prepared by two routes: (a) by the reaction of C-electrophiles with N-acetylindoxyl and (b) by the reaction of active methylene compounds with 2-chloroindole-3-one. The visible absorption spectra are recorded and discussed.