cssi/SciSciGPT-SciSciNet huggingface dataset:
Reconstructing sparse signals from their zero crossings

Classical sampling records the signal level at pre-determined time instances, usually uniformly spaced. An alternative implicit sampling model is to record the timing of pre-determined level crossings. Thus the signal dictates the sampling times but not the sampling levels. Logan's theorem provides sufficient conditions for a signal to be recoverable, within a scaling factor, from only the timing of its zero crossings. Unfortunately, recovery from noisy observations of the timings is not robust and usually fails to reproduce the original signal. To make the reconstruction robust this paper introduces the additional assumption that the signal is sparse in some basis. We reformulate the reconstruction problem as a minimization of a sparsity inducing cost function on the unit sphere and provide an algorithm to compute the solution. While the problem is not convex, simulation studies indicate that the algorithm converges in typical cases and produces the correct solution with very high probability.
Manifestation of random phase in a finite ensemble of a turbulent fluid

A field can be specified by a set of spectral coefficients, ${{c}_{j}(t)}$, relative to an expansion basis. In fluid turbulence, one often assumes the condition that if one were to extract data from an ensemble of realizations, one would find that the average, $〈{c}_{i}^{*}(t){c}_{{i}^{\ensuremath{'}}}(t)〉$, would vanish unless ${i\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}i}^{\ensuremath{'}}$, as in the case of a homogeneous ensemble in which the $i$'s represent wave vectors. We analytically treat an extension to the case in which one has a larger number of coefficients than realizations, introducing intrinsic linear dependences that vitiate the stated condition.
AUDITORY NERVE INPUTS TO COCHLEAR NUCLEUS NEURONS STUDIED WITH CROSS-CORRELATION

Abstract The strength of synapses between auditory nerve (AN) fibers and ventral cochlear nucleus (VCN) neurons is an important factor in determining the nature of neural integration in VCN neurons of different response types. Synaptic strength was analyzed using cross-correlation of spike trains recorded simultaneously from an AN fiber and a VCN neuron in anesthetized cats. VCN neurons were classified as chopper, primarylike, and onset using previously defined criteria, although onset neurons usually were not analyzed because of their low discharge rates. The correlograms showed an excitatory peak (EP), consistent with monosynaptic excitation, in AN–VCN pairs with similar best frequencies (49% 24/49 of pairs with best frequencies within ±5%). Chopper and primarylike neurons showed similar EPs, except that the primarylike neurons had shorter latencies and shorter-duration EPs. Large EPs consistent with end bulb terminals on spherical bushy cells were not observed, probably because of the low probability of recording from one. The small EPs observed in primarylike neurons, presumably spherical bushy cells, could be derived from small terminals that accompany end bulbs on these cells. EPs on chopper or primarylike-with-notch neurons were consistent with the smaller synaptic terminals on multipolar and globular bushy cells. Unexpectedly, EPs were observed only at sound levels within about 20 dB of threshold, showing that VCN responses to steady tones shift from a 1:1 relationship between AN and VCN spikes at low sound levels to a more autonomous mode of firing at high levels. In the high level mode, the pattern of output spikes seems to be determined by the properties of the postsynaptic spike generator rather than the input spike patterns. The EP amplitudes did not change significantly when the presynaptic spike was preceded by either a short or long interspike interval, suggesting that synaptic depression and facilitation have little effect under the conditions studied here.
Hepatocellular proliferation and hepatocarcinogen bioactivation in mice with diet-induced fatty liver and obesity.

Abstract Human liver cancer is in part associated with obesity and related metabolic diseases. The present study was undertaken in a mouse model of diet-induced obesity (DIO) and hepatic steatosis, conditions which can be associated with hepatic neoplasia, to determine whether the rates of cell proliferation or hepatocarcinogen bioactivation were altered in ways which could facilitate hepatocarcinogenesis. DIO mice were generated by feeding C57BL/6 (B6) male mice a high-fat diet beginning at 4 weeks of age; age-matched conventional lean (LEAN) B6 mice fed a low fat diet (10% Kcal from fat) were used for comparison. Groups of 28 week old DIO and LEAN mice were dosed with the bioactivation-dependent DNA-reactive hepatocarcinogen 2-acetylaminofluorene (AAF), at 2.24 or 22.4 mg/kg, given by gavage 3 times per week for 31 days, or received no treatment (DIO and LEAN control groups). Compared with the LEAN control group, the DIO control group had a higher mean body weight (16.5 g), higher mean absolute (1.4 g) and mean relative (25.5%) liver weights, higher (394%) liver triglyceride concentrations, and an increased incidence and severity of hepatocellular steatosis at the end of the dosing phase. The DIO control group also had a higher mean hepatocellular replicating fraction (31% increase, determined by proliferating cell nuclear antigen immunohistochemistry). Hepatocarcinogen bioactivation, based on formation of AAF DNA adducts as measured by nucleotide 32P-postlabeling, was similar in both DIO and LEAN AAF-dosed groups. Thus, hepatocellular proliferation, but not hepatocarcinogen bioactivation, was identified as an alteration in livers of DIO mice which could contribute to their susceptibility to hepatocarcinogenesis.
Dislocation dynamics. II. Applications to the formation of persistent slip bands, planar arrays, and dislocation cells

The dynamic organization of dislocations into spatially heterogeneous substructures is demonstrated by applying the principles of dislocation dynamics that were outlined in the preceding paper. Here it is shown that the formation of persistent slip bands is a consequence of the competition between dipole formation and annihilation of dislocations of opposite Burgers vectors in the absence of temperature-enhanced climb recovery under cyclic stress conditions. Planar arrays, which are also uniaxial structures, are shown to arise from enhanced dislocation multiplication and the formation of stable dipole configurations along a slip plane at lower temperatures where climb is unimportant. Biaxial dislocation systems experience additional degrees of freedom compared with uniaxial systems because of available motion along additional slip systems. It is demonstrated that for a system of orthogonal slip directions at high temperatures in which climb and glide motion are competitive, dislocation cellular structures form as a result of immobile dipole and junction formation and by the internal elastic strain energy minimization caused by long-range self-shielding. It is shown that the internal elastic strain energy is reduced by the self-organization process. However, the short-range nonlinear processes (i.e., dipole and junction formation) are shown not to allow absolute elastic energy minimization.
Conjugacies in the plane of a triangle

In the literature of triangle geometry, there are several kinds of conjugacies. The purpose of this paper is to recognize and generalize the functional forms for these conjugacies as represented in homogeneous coordinates. We introduce the U-Hirst inverse of X, which is a conjugacy given for points U = u : v : w and X = x : y : z by \( U \diamond X = vwx^2 - yzu^2:wuy^2 - zxv^2 : uvz^2 - xyw^2 \). Since \( U \diamond X = X \diamond U \), the operation \( \diamond \) is commutative. Another such case is isoconjugacy, given by \( U\,cX = vwyz\,:\,wuzx\,:\,uvxy \) and exemplified by the well-known isogonal and isotomic conjugacies. Others, such as line conjugacies and Ceva conjugacies, are represented by noncommutative operations. Diamond and line conjugacies are members of a two-parameter family of online conjugacies, whereas isoconjugacy and Ceva conjugacy are members of a two-parameter family of offline conjugacies. To the extent that these conjugacies are projective involutions, the underlying projective theory is well known.
Hartz and Minds: The Liberal Tradition after the Cold War

The Liberal Tradition in America is truly an exceptional book. Its conceptual framework has been widely criticized as wrongheaded, and each of its organizing theses has been held to be historically inaccurate. Nonetheless, it continues to figure as a central text for scholars in political studies and American studies. We teach it regularly in graduate seminars, allow the problems it raises to shape our research agendas, and organize symposia to commemorate the fiftieth anniversary of its publication. Indeed, it is tempting to suggest that, if nothing else, Louis Hartz long ago proved that it is more desirable to be interesting than to be right. To that end, I write here to register an appreciation of his work even as I acknowledge the aptness of much of the criticism to which it has been subjected. To my mind, a Hartz who has been refined and reframed by decades of criticism can still offer valuable insight into America and America's engagement with the world, particularly in a moment of caustic political and sharp economic divisions that would seem to belie the consensus he emphasized, and in the midst of the emergence of forthrightly illiberal doctrines shaping both American domestic and foreign policy.
Simultaneous Repair of Sigmoid Colon Conduit Fistula and Neovagina Construction in a Patient with Bladder Exstrophy

Recurrent urogynecologic complications in women with bladder exstrophy are common and complex given the congenital abnormalities of the bony, connective tissue, and muscular support of the pelvic floor, as well as the length and axis of the vagina. Management of these issues is challenging and often requires unique surgical strategies. We present the case of a distinct, individualized surgical approach to management of several complicated urogynecologic issues in a woman with bladder exstrophy who desired surgical correction of a non-healing fistula, pelvic organ prolapse, and a short vagina.
p27 Kip1 nuclear localization and cyclin-dependent kinase inhibitory activity are regulated by glycogen synthase kinase-3 in human colon cancer cells.

The cellular mechanisms regulating intestinal differentiation are poorly understood. Sodium butyrate (NaBT), a short-chain fatty acid, increases p27Kip1 expression and induces cell cycle arrest associated with intestinal cell differentiation. Here, we show that treatment of intestinal-derived cells with NaBT induced G0/G1 arrest and intestinal alkaline phosphatase, a marker of differentiation, activity and mRNA expression; this induction was attenuated by inhibition of glycogen synthase kinase-3 (GSK-3). Moreover, treatment with NaBT increased the nuclear, but not the cytosolic, expression and activity of GSK-3β. NaBT decreased cyclin-dependent kinase CDK2 activity and induced p27Kip1 expression; inhibition of GSK-3 rescued NaBT-inhibited CDK2 activity and blocked NaBT-induced p27Kip1 expression in the nucleus but not in the cytoplasm. In addition, we demonstrate that NaBT decreased the expression of S-phase kinase-associated protein 2 (Skp2), and this decrease was attenuated by GSK-3 inhibition. Furthermore, NaBT increased p27Kip1 binding to CDK2, which was completely abolished by GSK-3 inhibition. Overexpression of an active form of GSK-3β reduced Skp2 expression, increased p27Kip1 in the nucleus and increased p27Kip1 binding to CDK2. Our results suggest that GSK-3 not only regulates nuclear p27Kip1 expression through the downregulation of nuclear Skp2 expression but also functions to regulate p27Kip1 assembly with CDK2, thereby playing a critical role in the G0/G1 arrest associated with intestinal cell differentiation.
CH3O+CO removal rate constant measurements over the 473–973 K temperature range

Abstract Removal rate constants for CH 3 O by CO have been measured over the temperature range 473–973 K using a laser photolysis/laser-induced fluorescence technique. For temperatures exceeding 773 K, the removal rate constant begins to exhibit a non-linear Arrhenius behavior suggesting that other removal processes, in addition to oxidation of CO by CH 3 O, are important at elevated temperatures.
Image Migration In A Three Level Data Base Archive System

Data base archive systems (DBAS) for picture archiving and communications systems (PACS) require very large storage devices for the digital images. The images, as large as 50 Mega-bits, are stored and retrieved simultaneously at the DBAS. The response time to the user for image storage and retrieval must be of the order of two seconds. Consequently, the image storage at the DBAS must be efficient to process the image requests in the required time. This paper describes an image migration algorithm for efficiently storing and moving the images within the DBAS storage devices. The DBAS storage devices are structured in a three level hierarchical architecture. Level 1 is composed of high speed magnetic disks and contains recent images, up to seven days. Level 2 consists of automatic juke box optical disk systems and contains images up to 30 days old. Level 3 is a manual juke box optical disk system and contains storage for images up to 7-10 years. A fourth level is a manual archive for images greater than seven years. The DBAS migration algorithm was developed to migrate images within this three level storage structure. A migration model was developed to represent the image data flow between levels. The model can be used to determine the size of each level at any time and the amount of data flow between levels. The model is driven by image generation requests by the Imaging Equipment and image retrieval requests by the user workstations. The migration algorithm for the DBAS was included in the simulation of the entire PACS system, including the Image Network, DBAS, Imaging Equipment, and User Workstations. This paper presents the result of the simulation and shows the effect of the image migration algorithm on the channel utilization.
Four-dimensional guidance problem with control delays

This paper, assuming steady wind and zero sideslip, presents a discrete-time mathematical model to obtain a control law and three-dimensional flight path to guide an aircraft in a given time from a given initial state (position, velocity and heading) to a prescribed final state subject to the constraints on airspeed acceleration, and pitch and bank angles of the aircraft. For ease in implementing the control law, the control inputs are assumed to be delayed and are applied in a sequential fashion. The guidance problem is formulated as a discrete nonlinear optimal control problem with time delays in dynamics and a cost functional of Bolza form. With a quadratic penalty function to handle terminal constraints on velocity and heading, a solution technique to the control problem based on conjugate gradient algorithm is investigated. Numerical examples are presented to illustrate the applicability of this approach to solution of a terminal area guidance problem in an automated air traffic control environment.
Enzymatic isolation of cells from neonatal calvaria using two purified enzymes from Clostridium histolyticum

The enzymatic isolation of cells with bacterial collagenase has proved to be a powerful technique for the study of a wide variety of tissues. Unfortunately, for some applications such as the isolation of cells from membranous bone, the cellular damage that results from the exposure of the cells to cytotoxic contaminants of bacterial collagenase has limited the usefulness of this approach. The use of chromatographically purified collagenase alone is often ineffective or very slow to release cells from tissue. We have found that two enzymes are necessary and sufficient to isolate cells from neonatal mouse calvaria: purified collagenase and neutral protease. These two enzymes can be chromatographically purified on a preparative scale to yield 100 mg amounts of each enzyme. The purified enzymes can be recombined in amounts which will digest calvaria at the same rate as the crude bacterial collagenase from which they were derived. The cells that are isolated using the purified enzymes are undamaged, as indicated by the measurement of their equilibrium density on gradients of Ficoll and sodium metrizoate. Cells isolated with crude collagenase never reach an equilibrium density upon isopyknic centrifugation, whereas cells isolated with the purified enzymes reach an equilibrium density of 1.074 g/ml in 90 min.
An Escherichia coli rpoB mutation that inhibits transcription of catabolite-sensitive operons

The Escherichia coli rpoB636 mutant is defective in the transcription of lac and other catabolite-sensitive operons. The lac promoter variant, UV5, which is independent of cyclic AMP and the cyclic AMP receptor protein, CRP, was also defective in rpoB636 mutants. The activity of the lac UV5 promoter was restored to wild-type levels by deletion of cya (adenylate cyclase) or crp. Cyclic AMP and CRP apparently act as inhibitors of the rpoB636 RNA polymerase.
A Novel Cooling System to Reduce Thermally-Induced Errors of Machine Tools☆

This study explores a method to reduce thermally-induced errors of machine tools through temperature stabilization with compressed air. The method uses inexpensive, specially-shaped, silicon tubing with small slits. Compressed air forced through such tubing increases heat dissipation from the surface through Coanda-effect cooling. This paper describes experiments performed on a simulated heat source as well as a turning center to evaluate and improve the effectiveness of the method. The results show that this system, which can easily be applied to existing machines, can significantly reduce thermal drift and may be a viable alternative to other methods to reduce thermally-induced errors.
θ-Expansion and light-cone gauge fixing in curved superspace σ-models

Abstract A method for normal coordinate expansion of superspace σ-model actions is developed and used to obtain a covariant θ-expansion of the heterotic Green-Schwarz superstring in curved superspace. It is known that in the absence of background fermions the expansion terminates at order θ 2 in the light-cone gauge. An expression for the gauge-fixed action including background metric, torsion and Yang-Mills fields is given.
Voltammetric studies of electron-conducting modified bilayer lipid membranes

Abstract Planar bilayer lipid membranes containing different amounts of iodine have been investigated by use of cyclic voltammetry technique in purpose to examine the electronic behavior of such modified membrane acting as working electrode . It has been shown that suitably modified bilayer lipid membrane can act as a good conductor having the conductance per unit surface G * ( G * = 5 × 10 −1 ohm −1 cm −2 ). Several kinetic parameters of electron transfer for different donor substances present in bathing solution were evaluated on the basis of classical cyclic voltammetry theory.
Structure And Thermodynamics of Weakly Segregated Rod-Coil Block Copolymers

The self-assembly of a series of monodisperse rod−coil block copolymers is studied in the weak segregation limit. This unusual weakly segregated system consists of polyisoprene (PI) coil blocks and poly(alkoxyphenylene vinylene) (PPV) rod blocks solubilized with alkoxy side groups. The order to microphase disorder transition (ODT) and nematic isotropic (NI) transition are experimentally investigated to produce a rod−coil block copolymer phase diagram in a system that follows polymeric scaling relationships. Small-angle X-ray scattering (SAXS), transmission electron microscopy (TEM), polarized optical microscopy, depolarized light scattering, and wide-angle X-ray scattering (WAXS) are used to map the phase diagram. As the symmetric diblock copolymer is heated, a series of transitions from lamellar to nematic to isotropic phases are observed. The NI transition temperature decreases with increasing coil fraction, and at high coil fractions only an isotropic phase is observable. The phase behavior is in quali...
Explanation, rationality, and microeconomic theory

The microeconomic theorist attempts to explain the behavior of markets as resulting from the aggregation of the effects of actions of individual economic agents engaged in rational pursuit of the ends they have in view. Commonly, the conception of rational action employed in this enterprise is the one provided by decision theory. Because it cannot take into account information about how agents conceive the actions open to them and their possible outcomes, the decision-theoretic picture of rational action is a partial model. Partial models are subject to limits on their applications. Herbert A. Simon has argued that computational complexity considerations are sufficient to show that the limits on the application of the decision theoretic model to economic questions must be severe. Recent experimental investigations have begun to provide concrete information about those limits. Detailed examination of experiments concerning what is commonly called “the preference reversal phenomenon” leads to the conclusion that people do not have complete preference orderings for amounts of money and risky assets, even in situations which are much simpler than those encountered in real economic life. Since it is a fundamental assumption of orthodox microeconomic models that such orderings exist, such models are radically defective. Consequently, a different basis for microeconomic theorizing is needed. It is methodologically misguided to argue against this conclusion by pointing out that no other known basis accounts for the range of phenomena which the orthodox model does seem to explain.
Behavioral suppression following 3,4-methylenenedioxymethamphetamine.

Abstract Rotation in rats was employed as an assay of the central dopaminergic activity of 3,4-methylenedioxymethamphetamine (MDMA). This agent was observed to possess predominantly amphetamine-like actions at low doses. However, at higher doses it also appears to stimulate the depamine receptor directly. Following a third dose of MDMA, a significant decrease in rotation was evident to this drug and to amphetamine, suggesting a neurotoxic or long-term suppressive action of MDMA.
Thermodynamic consequences of disrupting a water-mediated hydrogen bond network in a protein:pheromone complex.

The mouse pheromones (±)-2-sec-butyl-4,5-dihydrothiazole (SBT) and 6-hydroxy-6-methyl-3-heptanone (HMH) bind into an occluded hydrophobic cavity in the mouse major urinary protein (MUP-1). Although the ligands are structurally unrelated, in both cases binding is accompanied by formation of a similar buried, water-mediated hydrogen bond network between the ligand and several backbone and side chain groups on the protein. To investigate the energetic contribution of this hydrogen bond network to ligand binding, we have applied isothermal titration calorimetry to measure the binding thermodynamics using several MUP mutants and ligand analogs. Mutation of Tyr-120 to Phe, which disrupts a hydrogen bond from the phenolic hydroxyl group of Tyr-120 to one of the bound water molecules, results in a substantial loss of favorable binding enthalpy, which is partially compensated by a favorable change in binding entropy. A similar thermodynamic effect was observed when the hydrogen bonded nitrogen atom of the heterocyclic ligand was replaced by a methyne group. Several other modifications of the protein or ligand had smaller effects on the binding thermodynamics. The data provide supporting evidence for the role of the hydrogen bond network in stabilizing the complex.
An Empirical Study of three Psychophysical Methods

Resume On a fait cette etude dans le but de comparer les valeurs d'echelle de 20 specimens d'ecriture selon des donnees obtenues par la Methode de Comparaisons Mises en Paires, la Methode d'Ordre de Merite, et la Methode D'Intervalles Egaux. On a obtenu les evaluations de l'excellence de l'ecriture des memes 370 sujets pour toutes les trois methodes. On a calcule les valeurs d'echelle pour la Methode d'Intervalles Egaux en faisant la courbe de frequence comulative selon les donnees de chaque, specimen, et en lisant la valeur du median directement du graphique. On donne ces valeurs d'echelle dans la Table 4. On a obtenu les valeurs d'echelle dans la Methode de Comparaisons Mises en Paires et la Methode d'Ordre de Merite en appliquant la Loi de Jugement Comparatif dans sa plus simple forme, Cas V. On donne ces valeurs d'echelle dans la Table 4. La coherence interne de ces calculations est montree par les tres petites differences entre les proportions experimentales et calculees. La difference moyenne est de...
Chemistry of singlet oxygen with arylphosphines

Abstract The chemistry of singlet oxygen with a variety of arylphosphines has been studied. Rates of singlet oxygen removal by para -substituted arylphosphines show good correlation with the Hammett σ parameter ( ρ =−1.53 in CDCl 3 ), and with the Tolman electronic parameter. The only products for the reactions of these phosphines with singlet oxygen are the corresponding phosphine oxides. Conversely, for ortho -substituted phosphines with electron-donating substituents, there are two products, namely a phosphinate formed by intramolecular insertion and phosphine oxide. Kinetic analyses demonstrate that both products are formed from the same intermediate, and this allows determination of the rate ratios for the competing pathways. Increasing the steric bulk of the phosphine leads to an increase in the amount of insertion product. VT NMR experiments show that peroxidic intermediates can only be detected for very hindered and very electron-rich arylphosphines.
Convergence of magno- and parvocellular pathways in layer 4B of macaque primary visual cortex.

EARLY visual processing is characterized by two independent parallel pathways: the magnocellular stream, which carries information useful for motion analysis, and the parvocellular stream, which carries information useful for analyses of shape and colour1–3. Although increasing anatomical and physiological evidence indicates some degree of convergence of the two streams, the pathway through layer 4B of primary visual cortex (VI) and on to higher cortical areas is usually considered to carry only magnocellular input1–3. This is inferred from anatomical descriptions of local circuitry in VI, and functional studies of area MT, which receives input from layer 4B4–7. We have directly measured the sources of local functional input to individual layer 4B neurons by combining intracellular recording and biocytin labelling with laser-scanning photostimulation8–10. We found that most layer 4B neurons receive strong input from both magno-cellular-stream-recipient layer 4Cα neurons and parvocellular-stream-recipient layer 4Cβ neurons. Thus higher cortical areas that receive input either directly or indirectly from layer 4B are likely to be more strongly influenced by the parvocellular pathway than previously believed.
The Effect of High and Low Intensity Cool-White Fluorescent Lighting on the Reproductive Performance of Turkey Breeder Hens

Large White turkey breeder hens were exposed to incandescent or cool-white (CW) fluorescent light of either high or low light intensity as the sole light source. Light treatments were quantified in both photometric and radiometric units for the entire visible spectrum as well as the 600 to 700 nm range of the visible spectrum. Photostimulation with these light sources occurred at 32 weeks of age and the subsequent effects on body weight, feed intake, and reproductive performance were observed over a 20-week egg laying period. Body weights and feed intakes were similar among the treatments. There were no significant differences in early season egg production (0 to 10 weeks) or fertility, hatchability, egg weight, and egg specific gravity due to light intensity or light source over the 20-week test period. However, CW fluorescent light delayed the onset of egg production from that of hens exposed to incandescent light (20.7 vs. 19.3 days, respectively) and significantly depressed late season (10 to 20 weeks) egg production from that observed in hens on incandescent light (23.9 vs. 31.9 eggs per hen, respectively). As a result, total egg production was significantly lower in the CW fluorescent (67.9 eggs/hen) than the incandescent treatment (75.2 eggs/hen). No significant differences in total eggs per hen occurred between the low and high light intensity treatments.(ABSTRACT TRUNCATED AT 250 WORDS)
T-Jump Infrared Study of the Folding Mechanism of Coiled-Coil GCN4-p1

Partially folded intermediates have been frequently observed in equilibrium and kinetic protein folding studies. However, folding intermediates that exist at the native side of the rate-limiting step are rather difficult to study because they often evade detection by conventional folding kinetic methods. Here, we demonstrated that a laser-induced temperature-jump method can potentially be used to identify the existence of such post-transition or hidden intermediates. Specifically, we studied two cross-linked variants of GCN4-p1 coiled-coil. The GCN4 leucine zipper has been studied extensively and most of these studies have regarded it as a two-state folder. Our static circular dichroism and infrared data also indicate that the thermal unfolding of these two monomeric coiled-coils can be adequately described by an apparent two-state model. However, their temperature-jump-induced relaxation kinetics exhibit non-monoexponential behavior, dependent upon sequence and temperature. Taken together, our results support a folding mechanism wherein at least one folding intermediate populates behind the main rate-limiting step.
A Raman-spectroscopic study of solution-crystallized polyethylenes

An analysis of the Raman internal modes of dilute-solution-crystallized homopolymers and co-polymers of ethylene has been made, similar to the work previously reported for the bulk-crystallized polymers. The crystallite structure can be described in terms of the relative amounts of the crystalline orthorhombic phase, the liquidlike amorphous phase, and the interfacial region. These quantities change with the molecular constitution of the chains and the crystallization conditions. The level of crystallinity decreases significantly with increasing counit content as would be expected. In addition, an appreciable interfacial structure develops in copolymers as compared with the homopolymers. A possible relationship between the interfacial content and the relaxation transitions in polyethylene is discussed.
The Employment Contract: A Test of the Transaction Cost Theory

This paper tests some predictions derived from Williamson's “transaction cost” theory of the organization of work, which holds that the form of the employment relationship is determined largely by the “idiosyncrasy” of work—that is, the nature of skills and knowledge used in production. It examines the occurrence of theoretically relevant provisions in collective bargaining agreements in the United States and finds they are related to a contract-level proxy for idiosyncrasy (based on bargaining structure) as predicted by the theory. An analysis of an individual-level variable, the difficulty of finding a comparable job, provides some additional support. Finally, several alternative explanations of the results are considered, and it is argued that none are consistent with the evidence. The analysis thus finds strong, if necessarily provisional, support for the theory.
Finite-Dimensional Lorentz Covariant Bifurcations

In this paper finite‐dimensional Lorentz covariant bifurcation equations are constructed and their properties, solutions, and gradient structures are examined. The possible applications of these ideas and techniques to elementary particle physics are considered.
To have and to hold: looking vs. touching in the study of categorization.

In order to make sense of the “blooming, buzzing, confusion” of a world where no two objects or events are ever exactly identical, infants form categories of perceptually distinct items that can be treated equivalently. The study of categorization often arises from one of two motivations: (1) to examine the mechanisms by which infants learn to treat distinct objects/events as equivalent (e.g., how an infant comes to name two different animals dog) and (2) to examine the current state of an infant's knowledge (e.g., does an infant have a category of dog?). As an illustration, consider Quinn et al.'s (1993) study. After habituating to different dog pictures, 3- and 4-month-olds do not dishabituate to cats. However, after habituating to cats, they do dishabituate to dogs. If we were examining the current state of knowledge, what should we conclude? Unless we want to suggest these infants are participants in Schrodinger's thought experiment (1935)—they both have and do not have a cat category—we cannot say anything conclusive. Instead, the results reveal something important about the mechanisms of categorization. Quinn et al. (1993) showed variability between category members affects the exclusivity of the categories infants form. This example demonstrates that studying whether infants have a category misses the crucial point that categories are neither things that people have in their heads nor that exist in the world; but rather categorization is a process (see also Oakes and Madole, 2000; Samuelson and Smith, 2000; Samuelson et al., 2007). In addition to these two main motivations, the study of categorization typically utilizes one of two methodologies: (1) looking measures, e.g., habituation and preferential looking, and (2) touching/reaching measures, e.g., sequential touching or manual forced choice measures. What I will argue in this paper is that looking measures (1) too readily lend themselves to interpretations of infants having a category or not, and (2) miss the importance the body and physical context have on development.
The molecular biology of retinoblastoma

Retinoblastoma, a rare pediatric eye tumor, has served as an important model for the heritable predisposition to cancer. The retinoblastoma protein, Rb , functions as a tumor suppressor by controlling progression through the cell cycle. Rb function is regulated primarily by its phosphorylation state, which is determined by the complex interaction of multiple kinases and their inhibitors that together form the ‘Rb pathway’. This pathway has been found to be functionally inactivated in almost all types of cancer. Despite recent advances in our understanding of Rb function, the precise role of Rb loss in the development of retinoblastoma remains unclear. Recent work in genetically altered mice has suggested that an additional mutation in another gene is required for retinal tumor formation. An alternative model presented here is based on the noncell-autonomous functions of Rb contributing to tumorigenesis.
Inflation, Translation and Conflicts in Statements of Financial Accounting Standards*

This paper utilizes the concept of aggregative consistency defined in Rubinstein and Fishburn [1986], and the FASB's concept of representational faithfulness to evaluate foreign currency translation and accounting for changing prices as embodied in SFAS 70. The paper shows that SFAS 70 produces measurement errors and creates a foreign currency translation adjustment which does not reflect the effects of exchange rate changes. The conditions defined in the paper also facilitate an evaluation of the relative merits of restate/translate and translate/restate. Restate/translate can conceivably be used if there is no consolidation. In the more usual case where consolidation is required, translate/restate using the relevant shareholders' consumption index will yield aggregatively consistent values under fewer restrictive conditions.
Anticipating undesired outcomes: The role of outcome certainty in the onset of depressive affect

Abstract We propose that the manner in which people anticipate future events influences the onset of depressive affect. In particular, we suggest that people are likely to experience depressive affect when they perceive highly aversive future events to be inevitable, i.e., 100 percent certain to occur. To test this hypothesis, we led participants to believe that the likelihood of experiencing an aversive event later in the experiment was either 0, 25, 50, 75, or 100%, while holding constant perceived uncontrollability. Results verified the notion that anticipating an undesired outcome that is inevitable produces significant increases in depressive affect. More specifically, a discrete increase in depression was observed when certainty reached 100% relative to anticipated likelihoods of 75, 50, 25, and 0%. Hence, depression did not simply increase linearly with increasingly high likelihoods that the aversive outcome would occur, but rather was a function of certainty. A similar but less pronounced pattern of findings was observed for increases in anxiety and hostility, indicating that these affects tended to co-occur with depressive affect. Overall, when a negative outcome is certain to occur, individuals may give up on the possibility of being spared the outcome and may become depressed as a result.
Polystyrene-bound cyclo-BINOLs. New heterogeneous ligands for asymmetric catalysis

Abstract BINOL and substituted BINOLs, which have been tethered between the 7 and 7′ sites (i.e. ‘cyclo-BINOLs’), can be attached via this linkage to polystyrene resins using a simple acetalization. Efficacy associated with these new ligands is demonstrated in heterogeneous asymmetric catalysis (e.g. aryl alkyl sulfide oxidations, and 1,2-additions of Et 2 Zn to aryl aldehydes).
Periodic Laughlin-Jastrow wave functions for the fractional quantized Hall effect

We present Laughlin-Jastrow wave functions for incompressible fluid states of two-dimensional electrons at Landau-level filling factor 1/m that satisfy periodic boundary conditions. This rederivation of Laughlin-type states emphasizes that it is correct short-distance behavior of the wave functions rather than angular momentum considerations that lie behind the explanation of the fractional quantized effect.
The Skp1 Protein from Toxoplasma Is Modified by a Cytoplasmic Prolyl 4-Hydroxylase Associated with Oxygen Sensing in the Social Amoeba Dictyostelium

In diverse types of organisms, cellular hypoxic responses are mediated by prolyl 4-hydroxylases that use O2 and α-ketoglutarate as substrates to hydroxylate conserved proline residues in target proteins. Whereas in metazoans these enzymes control the stability of the HIFα family of transcription factor subunits, the Dictyostelium enzyme (DdPhyA) contributes to O2 regulation of development by a divergent mechanism involving hydroxylation and subsequent glycosylation of DdSkp1, an adaptor subunit in E3SCF ubiquitin ligases. Sequences related to DdPhyA, DdSkp1, and the glycosyltransferases that cap Skp1 hydroxyproline occur also in the genomes of Toxoplasma and other protists, suggesting that this O2 sensing mechanism may be widespread. Here we show by disruption of the TgphyA locus that this enzyme is required for Skp1 glycosylation in Toxoplasma and that disrupted parasites grow slowly at physiological O2 levels. Conservation of cellular function was tested by expression of TgPhyA in DdphyA-null cells. Simple gene replacement did not rescue Skp1 glycosylation, whereas overexpression not only corrected Skp1 modification but also restored the O2 requirement to a level comparable to that of overexpressed DdPhyA. Bacterially expressed TgPhyA protein can prolyl hydroxylate both Toxoplasma and Dictyostelium Skp1s. Kinetic analyses showed that TgPhyA has similar properties to DdPhyA, including a superimposable dependence on the concentration of its co-substrate α-ketoglutarate. Remarkably, however, TgPhyA had a significantly higher apparent affinity for O2. The findings suggest that Skp1 hydroxylation by PhyA is a conserved process among protists and that this biochemical pathway may indirectly sense O2 by detecting the levels of O2-regulated metabolites such as α-ketoglutarate.
Has the surge in media attention increased public awareness about colorectal cancer and screening

The Centers for Disease Control and Prevention’s Screen for Life campaign in March 1999 followed by the creation of National Colorectal Cancer Awareness Month in March 2000 heralded a surge in media attention to promote awareness about CRC and stimulate interest in screening. Our objective was to assess whether these campaigns have achieved their goal of educating the public about CRC and screening. The study sample was comprised of mostly unscreened, average-risk, English-speaking patients aged 50–75 years seen in an urban primary care setting. Knowledge was assessed using a 12-item true/false questionnaire based primarily on the content of key messages endorsed by the National Colorectal Cancer Roundtable (Cancer 95:1618–1628, 2002) and adopted in many of the media campaigns. Multiple linear regression was performed to identify demographic correlates of knowledge. A total of 356 subjects (83% <age 65, 58% female, 60% Black, 7% Hispanic, 60% ≤high school degree, 31% prior FOBT ) were surveyed. Most respondents (≥67%) were aware of who gets CRC, age to initiate screening, the goals of screening and potential benefits. Fewer were aware that removing polyps can prevent CRC and that both polyps and CRC may be asymptomatic. Knowledge scores were lower among Blacks and those with a high school degree or less. Race and education were independent correlates of knowledge. These data suggest that recent media campaigns have been effective in increasing public awareness about CRC risk and screening but important gaps in knowledge remain.
SIGACT news complexity theory column 49

Warmest thanks to Neil Immerman for this issue's column, which is on Progress in Descriptive Complexity. (As you can see in this column, Neil is the rare writer whose italic lines truly deserve the italics.) This issue should reach your hands shortly before winter intersession, and I'd highly recommend that, if you don't already own Neil's wonderful book Descriptive Complexity ([I] in this column's bibliography), you consider visiting your school's library and bringing it home for holidays.
The ultrastructure of the human circumvallate papilla. I. Cilia of the papillary crypt.

Cilia-bearing cells have been observed near the bottom of the crypt of the human circumvallate papilla, between the lower taste buds and the duct of von Ebner's gland. It is likely that they serve one or more of the following functions: cleansing the papillary crypt, circulation of tastants, and bathing the pores of the taste bud in the various fluid secretions of the oral cavity. The kinetosomes of these cells were observed to possess typical transitional fibers and rootlets with periodic structure. In addition, a single, lateral, satellite-like projection from the midregion of the kinetosome was connected to microtubules which coursed deeply with the mitochondria-rich cytoplasm as did fine fibrils and some rootlets.
Role of sperm motility and acrosome integrity in the filtration of bovine semen

Abstract In this study, the role of sperm motility and acrosome integrity in filtration of bovine semen was investigated. In Experiment 1, the treatment of semen with formaldehyde, hyperosmotic buffer, heating and direct freezing immobilized the spermatozoa completely but their acrosomal status varied significantly (P 0.05) on the postfiltration recovery rate of motile spermatozoa. Filtered spermatozoa exhibited higher (P 90%), progressive motility (> 70%) and normal acrosomes (> 95%) than nonfiltered spermatozoa. In conclusion, sperm motility seems to be more important than acrosome integrity for semen filtration, and the Sephadex ion-exchange column can remove the known quantities of different kinds dead/immotile spermatozoa.
Angiographic predictors of reocclusion after thrombolysis: results from the Thrombolysis in Myocardial Infarction (TIMI) 4 trial.

Objectives. This study attempted to determine which lesion characteristics are associated with reocclusion by 18 to 36 h. Background. Reocclusion of the infarct-related artery after successful reperfusion is associated with significant morbidity and up to a threefold increase in mortality. Methods. Two hundred seventy-eight patients with acute myocardial infarction were randomized to receive either anisoylated plasminogen streptokinase activator complex (APSAC) or recombinant tissue-type plasminogen activator (rt-PA) or their combination. Culprit arteries were assessed for Thrombolysis in Myocardial Infarction (TIMI) flow grade, lesion ulceration, thrombus, collateral circulation and eccentricity. Minimal lumen diameter, percent diameter stenosis and lesion irregularity (power) were calculated using quantitative angiography. Results. Reocclusion was observed more frequently in arteries with TIMI 2 versus TIMI 3 flow (10.4% vs. 2.2%, p = 0.003), in ulcerated lesions (10.7% vs. 3.0%, p = 0.009) and in the presence of collateral vessels (18.2% vs. 5.6%, p = 0.03). Similar trends were observed for eccentric (7.3% vs. 2.3%, p = 0.06) and thrombotic (8.4% vs. 3.3%, p = 0.06) lesions. Reocclusion was associated with more severe mean percent stenosis (77.9% vs. 73.9%, p = 0.04). Lesion length, reference segment diameter and Fourier measures of lesion irregularity were not associated with reocclusion. Conclusions. Several simply assessed angiographic variables, such as the presence of TIMI grade 2 flow, ulceration, collateral vessels and greater percent diameter stenosis at 90 min after thrombolytic therapy, are associated with significantly higher rates of infarct-related artery reocclusion by 18 to 36 h and may aid in identifying the subset of patients who are at significantly higher risk of early reocclusion and who potentially warrant further early pharmacologic or mechanical intervention.
Somatic symptoms in primary care: etiology and outcome.

Although somatic complaints are the predominant reason for seeking general medical care, their etiology and prognosis remain poorly understood. In a random sample of the records of all patients visiting an urban primary care clinic during four 1-month periods, 289 patients had one or more somatic symptoms, a total of 433 symptoms. Using explicit criteria, physician raters classified nearly half (48%) of the symptoms as either psychiatric or idiopathic in etiology. Reviewing follow-up notes for 12 months after the index visit, raters found that at least one-fourth of the symptoms persisted. Independent predictors of symptom persistence were prior visits for the same symptom, symptom type (i.e., headache or back pain), male gender, and greater medical comorbidity (i.e., seven or more medical diagnoses). Developing better management strategies for prevalent, medically unexplained, persistent somatic symptoms is a health care priority.