cssi/SciSciGPT-SciSciNet huggingface dataset:
Rb regulates fate choice and lineage commitment in vivo

Mutation of the retinoblastoma gene (RB1) tumour suppressor occurs in one-third of all human tumours and is particularly associated with retinoblastoma and osteosarcoma. Numerous functions have been ascribed to the product of the human RB1 gene, the retinoblastoma protein (pRb). The best known is pRb's ability to promote cell-cycle exit through inhibition of the E2F transcription factors and the transcriptional repression of genes encoding cell-cycle regulators. In addition, pRb has been shown in vitro to regulate several transcription factors that are master differentiation inducers. Depending on the differentiation factor and cellular context, pRb can either suppress or promote their transcriptional activity. For example, pRb binds to Runx2 and potentiates its ability to promote osteogenic differentiation in vitro. In contrast, pRb acts with E2F to suppress peroxisome proliferator-activated receptor gamma subunit (PPAR-gamma), the master activator of adipogenesis. Because osteoblasts and adipocytes can both arise from mesenchymal stem cells, these observations suggest that pRb might play a role in the choice between these two fates. However, so far, there is no evidence for this in vivo. Here we use mouse models to address this hypothesis in mesenchymal tissue development and tumorigenesis. Our data show that Rb status plays a key role in establishing fate choice between bone and brown adipose tissue in vivo.
CROSS-COMMODITY PERSPECTIVE ON CONTRACTING: EVIDENCE FROM MISSISSIPPI

This analysis presents the results of a survey of agricultural producers in Mississippi regarding their use of contracting. The study focuses on cross-commodity dierences in contracting and the variable underlying contracting. Logistic regression models are used to examine the impacts of variables coming from transactions cost economics and risk on contracting decisions. Support is found for the eects of transactions cost, but price risk is not found to be an important determinant of contracting decisions.
Three-Dimensional Imaging Properties of Rotation-Free Square and Hexagonal Micro-CT Systems

We study the 3-D imaging properties of a rotation-free micro-computed tomography (CT) system with square and hexagonal geometries. These systems use linear arrays of carbon-nanotube-based X-ray sources that are individually addressable. The source arrays and area detectors in the square and the hexagonal geometries form the sides of a polygon. The tomographic angular sampling for both geometries requires no motion of the sources, the detectors, or the subject. We demonstrate that the hexagonal geometry has improved angular coverage as compared to the square geometry. The ordered-subset convex iterative algorithm is implemented in both geometries for reconstructions from cone-beam projection data. Simulation studies show that both geometries can be effectively reconstructed with polychromatic or monochromatic source spectra. As a result of the incomplete tomographic sampling of the two geometries, some streaking artifacts appear in the reconstructed images. The hexagonal geometry, in general, produces fewer streaking artifacts than the square geometry. On the other hand, the two geometries perform quite similarly in resolution-noise trade-off, so we conclude that the proposed geometries are comparably effective for the rotation-free micro-CT and the hexagonal geometry is superior in reducing streaking artifacts.
Data assimilation of glucose dynamics for use in the intensive care unit

We know much about the glucose regulatory system, yet the application of this knowledge is limited because simultaneous measurements of insulin and glucose are difficult to obtain. We present a data assimilation framework for combining sparse measurements of the glucose regulatory system, available in the intensive care unit setting, with a nonlinear computational model to estimate unmeasured variables and unknown parameters. We also demonstrate a method for choosing the best variables for measurement. We anticipate that this framework will improve glucose maintenance therapies and shed light on the underlying biophysical process.
UNITIZATION OF SPATIALLY CONNECTED RENEWABLE RESOURCES

Spatial connectivity of renewable resources induces a spatial externality in extraction. We explore the consequences of decentralized spatial property rights in the presence of spatial externalities. We generalize the notion of unitization—developed to enhance cooperative extraction of oil and gas fields—and apply it to renewable resources which face a similar spatial commons problem. We find that unitizing a common pool renewable resource can yield first-best outcomes even when participation is voluntary, provided profit sharing rules can vary by participant.
Finite Element Framework for Mechanics and Dynamics of Supramolecular Protein Assemblies

The conformational dynamics and mechanical properties of supramolecular protein assemblies play a central role in a broad array of cellular functions ranging from migration and division to transcription and translation. The finite element method (FEM) provides a natural framework for the computation of protein normal modes and mechanical response based either on atomic coordinates or electron density maps [1]. Here, we present development of the finite element framework for the computation of actin filament mechanics and solvent damping effects. A new normal modes data bank for structures in the electron microscopy data bank (EMDB [2]) is also presented.Copyright © 2010 by ASME
COLLISIONAL STRIPPING AND DISRUPTION OF SUPER-EARTHS

The final stage of planet formation is dominated by collisions between planetary embryos. The dynamics of this stage determine the orbital configuration and the mass and composition of planets in the system. In the solar system, late giant impacts have been proposed for Mercury, Earth, Mars, and Pluto. In the case of Mercury, this giant impact may have significantly altered the bulk composition of the planet. Here we present the results of smoothed particle hydrodynamics simulations of high-velocity (up to ~5v esc) collisions between 1 and 10 M ⊕ planets of initially terrestrial composition to investigate the end stages of formation of extrasolar super-Earths. As found in previous simulations of collisions between smaller bodies, when collision energies exceed simple merging, giant impacts are divided into two regimes: (1) disruption and (2) hit-and-run (a grazing inelastic collision and projectile escape). Disruption occurs when the impact parameter is near zero, when the projectile mass is small compared to the target, or at extremely high velocities. In the disruption regime, we derive the criteria for catastrophic disruption (when half the total colliding mass is lost), the transition energy between accretion and erosion, and a scaling law for the change in bulk composition (iron-to-silicate ratio) resulting from collisional stripping of a mantle.
Taxation and Corporate Financial Policy

A model of corporate financial policy (debt-equity ratios and dividend payout rates) is included in the Harberger general equilibrium model of incidence of the corporate income tax. Illustrative calculations of the distortions of financial policy and increases in risk premiums induced by the corporate tax are provided. Because risk premiums on corporate securities would be reduced, eliminating the corporate tax or integrating it into the personal tax would increase the income of noncorporate investors relatively more than that of investors in corporate securities, and is therefore less regressive than is commonly thought.
Diamond Deposition by a Nonequilibrium Plasma Jet

A nonequilibrium plasma jet has been used to deposit diamond films on a number of substrates, including silicon, silicon nitride, alumina, and molybdenum. Hydrogen is passed through a glow discharge and expanded through a supersonic nozzle to produce a highly nonequilibrium jet. Methane is added downstream of the nozzle, where it mixes and reacts with the nonequilibrium concentration of hydrogen atoms. The resulting supersonic jet strikes the substrate surface producing a high quality (determined by laser Raman spectrometry) adherent diamond film. Because of the low jet temperature, substrate cooling is unnecessary. Diamond deposition rates have exceeded 2 mg/kWh and I μm/h averaged over 16 cm2 area; good quality films prepared at substrate temperatures below 600 K. have been
Design of finite-time stabilizing controllers for nonlinear dynamical systems

Finite-time stability involves dynamical systems whose trajectories converge to an equilibrium state in finite time. Since finite-time convergence implies nonuniqueness of system solutions in reverse time, such systems possess non-Lipschitzian dynamics. Sufficient conditions for finite-time stability have been developed in the literature using Holder continuous Lyapunov functions. In this paper, we extend the finite-time stability theory to revisit time-invariant dynamical systems and to address time-varying dynamical systems. Specifically, we develop a Lyapunov-based stability and control design framework for finite-time stability as well as finite-time tracking for time-varying nonlinear dynamical systems. Furthermore, we use the vector Lyapunov function approach to study finite-time stabilization of compact sets for large-scale dynamical systems. Copyright © 2008 John Wiley & Sons, Ltd.
1,3-Alternate calix[4]arene nitronyl nitroxide tetraradical and diradical: synthesis, X-ray crystallography, paramagnetic NMR spectroscopy, EPR spectroscopy, and magnetic studies

Calix[4]arenes constrained to 1,3-alternate conformation and functionalized at the upper rim with four and two nitronyl nitroxides have been synthesized, and characterized by X-ray crystallography, magnetic resonance (EPR and 1H NMR) spectroscopy, and magnetic studies. Such calix[4]arene tetraradicals and diradicals provide scaffolds for through-bond and through-space intramolecular exchange couplings.
Three Dimensional Core-shell Superstructures: Mechanically Strong Aerogels

Nanocasting conformal polymer coatings on preformed three-dimensional assemblies of nanoparticles, macroscopically classified as aerogels, reinforces the interparticle necks and increases the strength of the bulk material dramatically. For example, specific compressive strengths are reported to be higher than those for mild steel and aluminum, while the ability to store energy may surpass that of armor grade ceramics. Specific chemistries have been developed for cross-linking skeletal nanoparticles with polyureas and polyurethanes, epoxies, and polystyrene, while the technology has been demonstrated with ~30 different nanoparticle networks in addition to silica.
Linear phase transition in random linear constraint satisfaction problems

Our model is a generalized linear programming relaxation of a much studied random K-SAT problem. Specifically, a set of linear constraints C on K variables is fixed. From a pool of n variables, K variables are chosen uniformly at random and a constraint is chosen from C also uniformly at random. This procedure is repeated m times independently. We are interested in whether the resulting linear programming problem is feasible. We prove that the feasibility property experiences a linear phase transition, when n ← ∞ and m = cn for a constant c. Namely, there exists a critical value c* such that, when c c*, the "distance" to feasibility is at least a positive constant independent of n. Our result is obtained using the combination of a powerful local weak convergence method developed in Aldous [Ald92], [Ald01], Aldous and Steele [AS03], Steele [Ste02] and martingale techniques. By exploiting a linear programming duality, our theorem implies some results for maximum weight matchings in sparse random graphs G(n, ⌊cn⌋) on n nodes with cn edges, where edges are equipped with randomly generated weights.
Cell–Cell Interaction with APC, not IL-23, Is Required for Naive CD4 Cells To Acquire Pathogenicity during Th17 Lineage Commitment

Subpopulations of pathogenic or nonpathogenic Th17 cells were reported to develop when presensitized CD4 cells were activated with their target Ag during polarization by either IL-23 or IL-6 and TGF-β, respectively. In this study, we generated two Th17 subpopulations by using a system in which naive CD4 cells from TCR transgenic mice specific to hen egg lysozyme (HEL) are polarized with IL-6/TGF-β and, concurrently, are activated either with HEL presented by APCs, or with anti-CD3/CD28 Abs. Only the former cells were pathogenic, inducing inflammation in eyes expressing HEL. Naive CD4 cells activated by the anti-CD3/CD28 Abs acquired pathogenicity, however, when cocultured with HEL/APC. Importantly, the naive CD4 cells did not acquire pathogenicity when cocultured with APCs stimulated with LPS or when separated from the HEL-presenting cells by a semipermeable membrane. Unlike with presensitized Th17, soluble IL-23 does not participate in pathogenicity acquisition by naive CD4 cells; no pathogenicity was induced by adding IL-23 to cultures activated with anti-CD3/CD28 Abs. Furthermore, Abs against IL-23 or IL-23R did not inhibit acquisition of pathogenicity in cultures of naive CD4 cells activated by HEL/APC. Our data thus show that, unlike presensitized CD4 cells, naive CD4 cells polarized toward Th17 phenotype acquire pathogenicity only by direct interaction with APCs presenting the Ag, with no apparent involvement of soluble IL-23. We suggest that the Th17 lymphocytes derived from naive CD4 cells participate in pathogenic and other immune processes, along with the IL-23-dependent Th17 cells.
Cramer-Von Mises Test†

The Cramer–von Mises test assesses whether two independent samples could have been drawn from the same or equivalent distributions. Keywords: equivalence of distributions; Smirnov test; empirical distribution function; permutation test
Inverse moment problem for elementary co-adjoint orbits

We give a solution to the inverse moment problem for a certain class of Hessenberg and symmetric matrices related to integrable lattices of Toda type.
Avoiding the curse of dimensionality in dynamic stochastic games

Discrete-time stochastic games with a flnite number of states have been widely applied to study the strategic interactions among forward-looking players in dynamic environments. However, these games sufier from a \curse of dimensionality" since the cost of computing players’ expectations over all possible future states increases exponentially in the number of state variables. We explore the alternative of continuous-time stochastic games with a flnite number of states, and show that continuous time has substantial computational and conceptual advantages. Most important, continuous time avoids the curse of dimensionality, thereby speeding up the computations by orders of magnitude in games with more than a few state variables. Overall, the continuous-time approach opens the way to analyze more complex and realistic stochastic games than currently feasible.
Properties of plutonium and its alloys for use as fast reactor fuels

Abstract Early interest in metallic plutonium fuels for fast reactors led to much research on plutonium alloy systems including binary solid solutions with the addition of aluminum, gallium, or zirconium and low melting eutectic alloys with iron and nickel or cobalt. There was also interest in ternaries of these elements with plutonium and cerium. The solid solution and eutectic alloys have most unusual properties, including negative thermal expansion in some solid-solution alloys and the highest viscosity known for liquid metals in the Pu–Fe system. Although metallic fuels have many potential advantages over ceramic fuels, the early attempts were unsuccessful because these fuels suffered from high swelling rates during burn up and high smearing densities. The liquid metal fuels experienced excessive corrosion. Subsequent work on higher melting U–Pu–Zr metallic fuels was much more promising. In light of the recent rebirth of interest in fast reactors, we review some of the key properties of the early fuels and discuss the challenges presented by the ternary alloys.
An improved double-tilt stage for the AEI EM7 high-voltage electron microscope

SUMMARY Vibration transmitted by the specimen rod of a side-entry stage frequently decreases image resolution, and the length of the rod in the high-voltage electron microscope can make the problem severe. A detachable tip clamped to the translation stage minimizes the effect, but eliminates the rod as a means of tilting. Furthermore, the second tilt mechanism is usually built into the rod. Thus the sample is coupled not clamped to the rod, increasing the effect. The image resolution attainable with our double-tilt stage was 1·5 nm along the rod's axis and 5·0 nm perpendicular to it before modification. An isotropic resolution of 0·5 nm was achieved by attaching the specimen tip to the rod with a flexible coupling and clamping both ends of the tip to the translation ring. The couplings used transmit the torque to rotate the specimen holder but dampen vibration. Ion-pumping the vacuum system with all other pumps off also improved specimen stability.
On Robustness Properties of Beta Encoders and Golden Ratio Encoders

The beta encoder was recently proposed as a quantization scheme for analog-to-digital (A/D) conversion; in contrast to classical binary quantization, in which each analog sample xisin[-1, 1] is mapped to the first N bits of its base-2 expansion, beta encoders replace each sample x with its expansion in a base beta between 1<beta<2. This expansion is nonunique when 1<beta<2, and the beta encoder exploits this redundancy to correct inevitable errors made by the quantizer component of its circuit design. The multiplier element of the beta encoder will also be imprecise; effectively, the true value beta at any time can only be specified to within an interval [betalow, betahigh]. This problem was addressed by the golden ratio encoder (GRE), a close relative of the beta encoder that does not require a precise multiplier. However, the GRE is susceptible to integrator leak in the delay elements of its hardware design, and this has the same effect of changing beta to an unknown value. In this paper, we present a method whereby exponentially precise approximations to the value of beta in both GREs and beta encoders can be recovered amidst imprecise circuit components from the truncated beta expansions of a rdquotestrdquo number x testisin[-1, 1] and its negative counterpart -x test. That is, beta encoders and GREs are robust with respect to unavoidable analog component imperfections that change the base beta needed for reconstruction.
The response of household parental investment to child endowments

The theoretical and empirical literature on parental investment focuses on whether child-specific parental investments reinforce or compensate for a child’s initial endowments. However, many parental investments, such as neighborhood quality and family size and structure, are shared wholly or in part among all children in a household. The empirical results of this paper imply that such household parental investments compensate for low endowments, as proxied by low birth weight.
Structural change of graphite during electron irradiation

Highly oriented pyrolytic graphite was irradiated at room temperature with 300-keV electrons. High resolution transmission electron microscopy and electron energy loss spectroscopy were employed to study the structure of electron-irradiated graphite. Results consistently indicated absence of long-range order periodicity in the basal plane, and loose retention of the c-axis periodicity. Structure was modeled based on a mixture of sixfold and non-sixfold atom rings. Formation of non-sixfold atom rings was related to the observed buckling and discontinuity of the original graphite basal plane.
Sub-therapeutic Antibiotics and the Efficiency of U.S. Hog Farms

Antimicrobial drugs are frequently fed to hogs at sub-therapeutic levels to promote feed efficiency and growth. However, in response to concerns that sub-therapeutic antibiotics (STAs) are promoting the development of antimicrobial drug-resistant bacteria, the U.S. Food and Drug Administration recently adopted a strategy to phase out antibiotics for such "production uses." This study uses a stochastic frontier model to estimate the costs to U.S. hog producers of a ban on STAs for growth promotion. To address potential sample selection issues, we employ a recently developed empirical approach that corrects for biases from both observed and unobserved variables.
Thermal Conductance of Metallic Interface in Vacuum

In most heat transfer applications, the deposited heat is transfered by any of the following classical methods: conduction, convection, radiation, or any combinations of these three. Depending on how critical the nature is of the designed equipment, the response time must be short enough in order to safeguard the proper performance of the devices. For instance, currently at the National Synchrotron Light Source (NSLS), various hardware equipment are being designed to intercept or to stop intense radiation beams induced by insertion devices such as wiggler and undulators. Due to the nature of some of these designs, the deposited high flux thermal load must be transferred across unbonded contact surfaces. Since any miscalculation would result in the disintegration of exposed material and therefore cause substantial problems, a true actual conductance measurement of the material in question is highly desirable. In the following three sections, background summary, the method of measurement, and the obtained results are discussed.
A new synthesis of 2-fluoro-1-naphthols

A general synthesis of 2-fluoro-1-naphthols in two steps from 1-indanones is reported. The 1-indanones are first converted to difluoromethyl 2-fluoro-1-napthyl ethers by reaction with difluorocarbene source, trimethylsilyl 2-fluorosulfonyl-2,2-difluoroacetate (TFDA). These ethers are then converted in high yield to the respective naphthols by heating with a mixture of acetic acid and 48% HBr.
Novel rearrangements of chiral 3-oxazolidinylazetidin-2-ones

Abstract Reaction of a 3-oxazolininyl-4-hydroxymethylazetidin-2-one with excess NaOMe in refluxing methanol gives the corresponding 4-oxa-1,8-diazabicyclo[4.3.0]nonan-5,9-dione stereospecifically in nearly quantitative yield via a novel skeletal rearrangement, which includes a gamma-lactone as a key-intermediate; Possible mechanisms and similar rearrangement in a related system is discussed.
Hash Function Balance and Its Impact on Birthday Attacks

Textbooks tell us that a birthday attack on a hash function h with range size r requires r 1/2 trials (hash computations) to find a collision. But this is quite misleading, being true only if h is regular, meaning all points in the range have the same number of pre-images under h; if h is not regular, fewer trials may be required. But how much fewer? This paper addresses this question by introducing a measure of the “amount of regularity” of a hash function that we call its balance, and then providing estimates of the success-rate of the birthday attack, and the expected number of trials to find a collision, as a function of the balance of the hash function being attacked. In particular, we will see that the number of trials can be significantly less than r 1/2 for hash functions of low balance. This leads us to examine popular design principles, such as the MD (Merkle-Damgard) transform, from the point of view of balance preservation, and to mount experiments to determine the balance of popular hash functions.
A simple and versatile method for the synthesis of acetals from aldehydes and ketones using bismuth triflate.

Acetals are obtained in good yields by treatment of aldehydes and ketones with trialkyl orthoformate and the corresponding alcohol in the presence of 0.1 mol % Bi(OTf)3·4H2O. A simple procedure for...
Symbolic approaches for finding control strategies in Boolean networks

We present an exact algorithm, based on techniques from the field of Model Checking, for finding control policies for Boolean Networks (BN) with control nodes. Given a BN, a set of starting states, I, a set of goal states, F, and a target time, t, our algorithm automatically finds a sequence of control signals that deterministically drives the BN from I to F at, or before time t, or else guarantees that no such policy exists. Despite recent hardness-results for finding control policies for BNs, we show that, in practice, our algorithm runs in seconds to minutes on over 13,400 BNs of varying sizes and topologies, including a BN model of embryogenesis in Drosophila melanogaster with 15,360 Boolean variables. We then extend our method to automatically identify a set of Boolean transfer functions that reproduce the qualitative behavior of gene regulatory networks. Specifically, we automatically learn a BN model of D. melanogaster embryogenesis in 5.3 seconds, from a space containing 6.9 × 1010 possible models.
Endocrine comparison of obese menstruating and amenorrheic women.

10 examine the relationship between obesity and chronic anovulation, we compared basal serum LH, FSH, and PRL levels, determined at 20-min intervals, and basal C21 [progesterone, 17- hydroxyprogesterone , pregnenolone, 17-hydroxypregnenolone ( 17Pe ), and cortisol], C19 [testosterone (T), delta 4-androstenedione (A), and dehydroepiandrosterone] and C18 (estrone and estradiol) steroid hormone concentrations measured at 1- to 2-h intervals for a 24-h period in five normal weight cycling women (NC) and in two groups of weight-matched obese women. Five of the obese women were regularly cycling (OC), and six were amenorrheic (OA). Sex hormone-binding globulin (SHBG) and non-SHBG-bound T and estradiol concentrations were also measured in each woman. Compared to NC women, OC women had normal basal protein and steroid hormone concentrations, except for reduced 17Pe levels (P less than 0.05). Mean SHBG concentrations were reduced by approximately 30%, and non-SHBG-bound T was increased by 70%, although the differences were not significant. In addition, when six precursors of testosterone (pregnenolone, 17Pe , dehydroepiandrosterone, progesterone, 17-hydroxyprogesterone, and A) were considered together as a group and the data analyzed by the kappa 2 test, a reduction in basal levels of these precursors was found in OC women relative to those in NC women (P less than 0.005). In OA women, mean concentrations of SHBG were markedly reduced and those of total T, A, estrone, and non-SHBG-bound T were significantly increased compared to those in both NC and OC women. Mean 24-h concentrations of LH tended to be greatest and FSH lowest in this group, but were not significantly different from those in the other groups. The mean LH pulse frequency was significantly greater in OA than in OC women (P less than 0.05). Mean 24-h PRL and cortisol levels were also reduced in OA women relative to those in NC women. These data suggest the possibility of a compensatory decline in total T production in OC women in an attempt to maintain normal hormonal homeostasis; as a consequence, ovulation continues in a cyclic fashion. In OA women, such compensatory mechanisms are no longer operative. Instead, a central and/or peripheral defect, resulting in overproduction of androgen, may also exist and lead to anovulation in OA women. In conclusion, our data imply that obesity is not a primary factor causing chronic anovulation. However, obesity may aggravate an already existing subtle defect in some women and result in amenorrhea.
Methane: a new frontier in organometallic chemistry

The base hydrocarbon of natural gas, methane, is one of the most unreactive hydrocarbons in terms of C–H bond dissociation enthalpy, ionization potential, and pKa. A perspective on the C–H activation of this potent greenhouse gas, by homogeneous and well-defined organometallic complexes is presented, with an emphasis on several recent advances in this field.
Special random numbers : Beyond the illusion of control

Previous research has shown that gamblers prefer numbers they choose themselves because this choice allows them to feel more in control of the (random) outcome. We identify other conditions under which people Wnd numbers “special” (i.e., worthy of betting more on than other numbers). By manipulating gambling task type and assigning participants a number by an endogenous system outside their own control (as is done in numerology, astrology, and other paranormal systems), we Wnd that indeed people prefer to bet on numbers derived from particular special systems. The mechanism underlying this preference is enjoyment with the task—not control. Further, the enjoyment associated with this “specialness” is related to the prevalence of certain types of numbers (i.e., numbers based on dates and names) in the fortune-telling world and not to other factors such as individuality or even belief in the associated system. We replicate these Wndings using actual money and show that this prevalence-to-enjoyment link already exists in memory for dates and names and is activated and strengthened by priming the fortune-telling systems relevant to those special random numbers. Finally, we present a model of special random numbers that integrates our Wndings with other determinants of valuation such as regret and subjective probability. Our results expand the realm of special random numbers beyond control. Our enjoyment model has implications not only for understanding gambling, but also for understanding how reasoning under uncertainty is inXuenced by little-understood phenomena (such as fortune-telling systems) without aVecting subjective probability or actual beliefs.
A game theoretic framework for incentives in P2P systems

Peer-to-peer (P2P) networks are self-organizing, distributed systems, with no centralized authority or infrastructure. Because of the voluntary participation, the availability of resources in a P2P system can be highly variable and unpredictable. We use ideas from game theory to study the interaction of strategic and rational peers, and propose a differential service-based incentive scheme to improve the system's performance.
Static modeling of dynamic recreation behavior: Implications for prediction and welfare estimation

Abstract This paper examines the consequences of using a static model of recreation trip-taking behavior when the underlying decision problem is dynamic. Specifically we examine the implications for trip forecasting and welfare estimation using a panel dataset of Lake Michigan salmon anglers for the 1996 and 1997 fishing seasons. We derive and estimate both a structural dynamic model using Bellman's equation, and a reduced-form static model with trip probability expressions mimicking those of the dynamic model. We illustrate an inherent identification problem in the reduced-form model that creates biased welfare estimates, and we discuss the general implications of this for the interpretation of preference parameters in static models. We then use both models to simulate trip taking behavior and show that although their in-sample trip forecasts are similar, their welfare estimates and out-of-sample forecasts are quite different.
Use of Fischer Plots to Define Third‐Order Sea‐Level Curves in Ordovician Peritidal Cyclic Carbonates, Appalachians

Fischer plots in which cumulative cycle thickness corrected for linear subsidence is plotted against time were originally used in the study of Triassic peritidal sequences to define short-duration departures in relative sea level in the Milankovitch range (104 to 105 yr). However, they also provide a means of assessing magnitude of third-order (1 to 10 m.y.) fluctuations in sea level which, on the basis of their regional correlatability, we ascribe to eustatic events.
An ultralow power athermal silicon modulator

Optical modulators on silicon promise to deliver ultralow power communication networks between or within computer chips. Here, the authors demonstrate a silicon modulator operating with less than one femtojoule energy and are able to compensate for thermal drift over a 7.5 °C temperature range.
Immunotherapy for cancer: synthetic carbohydrate-based vaccines

Aberrant glycosylation of glycoproteins and glycolipids of cancer cells, which correlates with poor survival rates, is being exploited for the development of immunotherapies for cancer. In particular, advances in the knowledge of cooperation between the innate and adaptive system combined with the implementation of efficient synthetic methods for assembly of oligosaccharides and glycopeptides is providing avenues for the rationale design of vaccine candidates. In this respect, fully synthetic vaccine candidates show great promise because they incorporate only those elements requires for relevant immune responses, and hence do not suffer from immune suppression observed with classical carbohydrate–protein conjugate vaccines. Such vaccines are chemically well-defined and it is to be expected that they can be produced in a reproducible fashion. In this feature article, recent advances in the development of fully synthetic sub-unit carbohydrate-based cancer vaccines will be discussed.
Decay of streamwise vorticity downstream of a three-dimensional protuberance

Streamwise vortices generated in boundary layers are known to persist for hundreds of boundary-laye r thicknesses. This remarkable property is the main topic of this paper. The particular case of the flowfield generated by a three-dimensional protuberance immersed in a flat plate boundary layer is studied using numerical modeling. Experimental measurements in a downstream crossflow plane are used to construct initial data for a marching calculation using the boundary-layer and boundary-region approximations; the latter includes crossflow diffusion terms. The former fails to predict the flowfield, but results from the latter agree qualitatively with aspects of the flowfield determined from the measurements of Tani et al. and are also in fair quantitative agreement.
Metal-silicate segregation in deforming dunitic rocks

We report the results of an investigation of the microstructural evolution of rocks composed of a silicate plus a molten metal sulfide phase deformed plastically in simple shear. Deformation experiments on samples of San Carlos olivine (Fo90) + 3, 5, or 9 vol% iron sulfide reveal the segregation of iron sulfide melt from the solid polycrystalline olivine matrix into regions enriched in metallic melt separated by regions depleted in the metallic melt. Previously published experimental studies on core-composition metals in silicate rocks, performed under hydrostatic pressure conditions, suggested that metallic melts could not segregate from silicates by porous flow below a critical melt fraction of ∼0.05. In contrast, we demonstrate that metallic melts can segregate from solid silicates by grain boundary percolation assisted by deformation, down to a pinch-off melt fraction of ∼0.01. The segregated metallic melt can accumulate into bands containing melt fractions exceeding 0.3. Using a model network of melt-rich sheets with melt fractions of 0.3, calculated Earth-scale permeabilities are as high as 10−9 m2. Segregation velocities for these sulfide melts can be up to 150 km/yr, fast enough for formation of Earth's core to proceed by deformation-induced segregation well within the geochemically determined timescale of 30 million years. Therefore plastic deformation can facilitate removal of large enough quantities of metallic liquid from a solid silicate mantle to satisfy the geochemical constraints of the inefficient core formation theory without invoking the presence of a magma ocean.
Application of Statistical Parameters in Defining Inlet Airflow Dynamics

During wind-tunnel and flight testing of several inlet duct designs, duct-pressure time histories were recorded on magnetic tape. Preliminary examination of the data indicated the pressure variations to be random processes having Gaussian distribution patterns. Reduction of these data by electronic analog instruments was made to obtain specific statistical parameters; namely, variance, time auto correlations and cross correlations, and power spectral densities. This paper discusses the utilization of these statistical parameters in helping to define the dynamic properties of the inlet duct and the state of the airflow turbulence. Examples are given illustrating the methods and techniques involved. HE inclusion of random phenomena as important governing factors in the design of modern aircraft systems introduces an element of uncertainty into the predictions of system responses. Consider the problem of flow instability in inlet ducts and its relation to engine stalls occurring in modern high-speed aircraft. As the inlet system operates more supercritically, boundary-layer flow separation increases, resulting in increased turbulence and spatial distortion at the engine compressor face. The onset of such conditions brings about stall in an apparently random manner; i.e., stall sometimes occurs immediately, sometimes several minutes of operation are possible without stall. If the occurrence of engine stall was a true random phenomenon, then it could not be controlled and, consequently, no further studies, statistical or otherwise, would prove useful. The engineering assumption, of course, is that stall is not a random phenomenon, but a function of nonrandom and controllable effects that can be determined from the flow properties of the inlet-engine system. The basic usefulness of statistical analysis for this study, therefore, lies precisely in its ability to separate the nonrandom effects from what seems to be the more or less random and unpredictable data. From pressure data taken during both wind-tunnel and flight test of several different inlets, statistical parameters were determined through data-reduction techniques offered by the electronic analog data-reduction instruments. The data were recorded during all stages of inlet operation, inAVERAGE PRESSURE AREAS (A+C+E-B-D) tf-tj
Radiation characteristics and turbulence–radiation interactions in sooting turbulent jet flames

A comprehensive modeling strategy including detailed chemistry, soot and radiation models coupled with state-of-the-art closures for turbulence–chemistry interactions and turbulence–radiation interactions is applied to various luminous turbulent jet flames. Six turbulent jet flames are simulated with Reynolds numbers varying from 6700 to 15,000, two fuel types (pure ethylene, 90% methane–10% ethylene blend) and different oxygen concentrations in the oxidizer stream (from 21% O2 to 55% O2). All simulations are carried out with a single set of physical and numerical parameters (model constants). A Lagrangian particle Monte Carlo method is used to solve a modeled joint probability density function (PDF) transport equation, which allows accurate closure for turbulence–chemistry interactions including nonlinear soot subprocesses. Radiation is calculated using a particle-based photon Monte Carlo method that is coupled with the PDF method to accurately account for both emission and absorption turbulence–radiatio...
Influence of molecular weight on crystallization rate of oriented, glassy nylon 6

Differential scanning calorimetry and wide angle X-ray diffractometry were used to investigate the effects of molecular weight and molecular weight distribution on the crystallization kinetics of oriented, glassy nylon 6. The samples had number average molecular weights ranging from 10,000 to 42,000 and polydispersity indices ranging from 2.0 to 3.1. Noncrystalline films were prepared by quenching molten films between plattens chilled with liquid nitrogen. These films were drawn 4X and 5-1/3X, and the resultant uniaxial orientation was observed to enhance markedly the room temperature crystallization kinetics. Although macroscopic deformation can be assumed to be affine at the molecular level, it is hypothesized that wholechain molecular relaxation occurs at rates inversely proportional to the square of molecular weight, thereby creating a distribution of extension ratios which reflect the actual molecular weight distribution. Thus, the crystallization rate and the degree of crystallinity depend on the fraction of high molecular weight molecules present in the sample. Given two samples with the same molecular weight, the one with the broader distribution crystallizes more rapidly. Similarly, samples having the larger molecular weight crystallize to a greater extent when two samples have the same molecular weight distribution.
Transition Structures of Hydrocarbon Pericyclic Reactions

Twenty-five years after the discovery of a vast class of organic reactions named “pericyclic reactions” by Woodward and Hoffmann, ab initio quantum mechanics provides a detailed analysis of the geometries, energies, and electronic characteristics of the transition structures of these reactions. Common features are found in all these reactions, and generalizations permit prediction of other transition-structure geometries and energies. At the same time, great diversity is observed—from strongly bonded, rigid, closed-shell entities to weakly interacting, flexible diradical structures.
Instanton analysis of Low-Density Parity-Check codes in the error-floor regime

In this paper we develop instanton method introduced in V. Chernyak et al. (2004), M.G. Stepanov et al. (2005) to analyze quantitatively performance of low-density parity-check (LDPC) codes decoded iteratively in the so-called error-floor regime. We discuss statistical properties of the numerical instanton-amoeba scheme focusing on detailed analysis and comparison of two regular LDPC codes: Tanner's [155,64,20] and Margulis' [672,336,16] codes. In the regime of moderate values of the signal-to-noise ratio we critically compare results of the instanton-amoeba evaluations against the standard Monte Carlo calculations of the frame-error-rate
Critical area computation for missing material defects in VLSI circuits

We address the problem of computing critical area for missing material defects in a circuit layout. The extraction of critical area is the main computational problem in very large scale integration yield prediction. Missing material defects cause open circuits and are classified into breaks and via blocks. Our approach is based on the L/sub /spl infin// medial axis of polygons and the weighted L/sub /spl infin// Voronoi diagram of segments. We also introduce the min-max Voronoi diagram of rectangles, a combinatorial structure of independent interest. The critical area problem for breaks and via blocks is reduced to variations of weighted L/sub /spl infin// Voronoi diagram of segments. Plane sweep algorithms to compute the appropriate Voronoi diagrams for each case are presented. As a result, the critical area for breaks and via blocks on a single layer can be computed accurately in one pass of the layout. The time complexity is O(n log n) in the case of breaks and O((n+K)log n) in the case of via blocks, where n is the size of the input and K is upper-bounded by the number of interacting vias (in practice K is small). The critical area computation assumes square defects and reflects all possible defect sizes following the D(r)=r/sub 0//sup 2//r/sup 3/ defect size distribution. The method is presented for rectilinear layouts.
Anaphylactoid reactions to protamine: An often lethal complication in insulin-dependent diabetic patients undergoing vascular surgery****

Protamine is used routinely at our institution during arterial surgery to reverse the anticoagulant effect of heparin. Adverse fatal reactions to protamine are generally believed to be rare. However, major anaphylactoid reactions occurred in 11 of the last 1150 patients receiving this drug at our institution. Nine of these reactions occurred in 325 insulin-dependent diabetic patients (incidence, 3%), whereas only two occurred in the 825 patients not receiving insulin (incidence, 0.2%) (p less than 0.001). Ten of these reactions occurred within 10 minutes of protamine administration (15 to 35 mg), whereas one reaction occurred immediately after administration of a 5 mg test dose of protamine. Systolic blood pressure fell below 60 mm Hg in all of the 11 patients, and three patients had to be resuscitated with closed-chest massage. Initial treatment with epinephrine and steroids was successful in seven cases. Four patients required further resuscitative measures, including closed-chest massage. However, one of the patients died as a result of ventricular fibrillation resistant to treatment. Ten of the 11 patients, including the patient who died, had significant preexisting cardiac disease; six of the surviving 10 patients (60%) had perioperative myocardial infarctions and three died. Thus the total mortality rate was 36% (4/11). These data support the implication that neutral protamine Hagedorn (NPH) insulin produces an adverse reaction through immunologic presensitization of the patient. These data also show that, in the older vascular surgery population with a high incidence of significant cardiac disease, protamine reactions can be potentially lethal. Thus routine use of protamine should be avoided in diabetic patients receiving insulin.
Endogenous timing of actions under conflict between two types of second mover advantage

In a model, two players, heterogeneous in their information quality, compete with each other with perfect information about the other player’s information quality. If they can decide their timings of actions endogenously, the less-informed player has an incentive to delay her action for learning. On the other hand, the more-informed player wants to delay her action to prevent her information from being revealed, not to enable her to learn. The consict of these two types of second mover advantages yields a war of attrition. Although both players can beneÞt from acting as the follower, the gain from a delay for learning is greater than that for preventing the other’s learning. Therefore, a cost for the delay in action plays an important role in characterizing the equilibrium. In contrast to the literature, in which only informational externalities are considered, this article shows that the introduction of payoff externalities contributes to different procedures and reasoning processes through which the heterogeneous players’ timings of actions are decided endogenously.
The 25th Anniversary of the Chernobyl Accident

The nuclear accident at the Chernobyl plant in 1986 is described and a summary of its immediate effects on people and the environment outlined. Then there is a summary of the important parts of the literature on diseases and deaths resulting from radiation and mortalities to date and the way mortality data became increasingly conservative over the years is discussed. Today, there is still uncertainty about future mortalities dues to long latency periods for many cancers however cancer deaths in Chernobyl affected regions are expected to be similar to non-Chernobyl controls. The major literature on environmental effects on wild species, forests, water and agricultural land are then reported with a brief discussion of remediation work and of current trends. Finally, contemporary perceptions of the Chernobyl accident are described in the context of popular anti-nuclear sentiment that prevailed in 1986, the immense publicity surrounding the accident and the natural tendency of people to exaggerate prospects of unlikely, yet extreme, events.