cssi/SciSciGPT-SciSciNet huggingface dataset:
The CaaX specificities of Arabidopsis protein prenyltransferases explain era1 and ggb phenotypes.

Protein prenylation is a common post-translational modification in metazoans, protozoans, fungi, and plants. This modification, which mediates protein-membrane and protein-protein interactions, is characterized by the covalent attachment of a fifteen-carbon farnesyl or twenty-carbon geranylgeranyl group to the cysteine residue of a carboxyl terminal CaaX motif. In Arabidopsis, era1 mutants lacking protein farnesyltransferase exhibit enlarged meristems, supernumerary floral organs, an enhanced response to abscisic acid (ABA), and drought tolerance. In contrast, ggb mutants lacking protein geranylgeranyltransferase type 1 exhibit subtle changes in ABA and auxin responsiveness, but develop normally. We have expressed recombinant Arabidopsis protein farnesyltransferase (PFT) and protein geranylgeranyltransferase type 1 (PGGT1) in E. coli and characterized purified enzymes with respect to kinetic constants and substrate specificities. Our results indicate that, whereas PFT exhibits little specificity for the terminal amino acid of the CaaX motif, PGGT1 exclusively prenylates CaaX proteins with a leucine in the terminal position. Moreover, we found that different substrates exhibit similar Km but different kcat values in the presence of PFT and PGGT1, indicating that substrate specificities are determined primarily by reactivity rather than binding affinity. The data presented here potentially explain the relatively strong phenotype of era1 mutants and weak phenotype of ggb mutants. Specifically, the substrate specificities of PFT and PGGT1 suggest that PFT can compensate for loss of PGGT1 in ggb mutants more effectively than PGGT1 can compensate for loss of PFT in era1 mutants. Moreover, our results indicate that PFT and PGGT1 substrate specificities are primarily due to differences in catalysis, rather than differences in substrate binding.
Driver injury and fatality risk in two-car crashes versus mass ratio inferred using Newtonian mechanics

This paper aims at explaining the results of a recent empirical study that found that when cars of unequal mass crash into each other, the ratio of driver fatality risk in the lighter care to risk in the heavier car (the fatality risk ratio) increased as a power function of the ratio of the mass of the heavier car to that of the lighter car (the mass ratio). The present study uses two sources of information to examine the relationship between these same quantities: first, calculations based on Newtonian mechanics, which show that when two cars crash head-on into each other, the ratio of their changes in speed (delta-v) is inversely proportional to mass ratio; second, National Accident Sampling System data, which show how delta-v affects driver injury risk. The study is performed for fatalities and severe injuries and for unbelted and belted drivers. Combining the two sources of information gives the result that fatality risk ratio increases as a power function of mass ratio, the same functional form found in the empirical study. Because the study is rooted in Newtonian mechanics, it clearly and directly identifies physical mechanisms involved and leads to the conclusion that mass, as such, causes large differences in driver injury and fatality risk when cars of unequal mass crash into each other.
To Cooperate, or not to cooperate in imperfectly-known fading channels

In this paper, communication over imperfectly-known fading channels with different degrees of cooperation is studied. The three-node relay channel is considered. It is assumed that communication starts with the network training phase in which the receivers estimate the fading coefficients of their respective channels. In the data transmission phase, amplify-and-forward and decode-and-forward relaying schemes are employed. For different cooperation protocols, achievable rate expressions are obtained. These achievable rate expressions are then used to find the optimal resource allocation strategies. In particular, the fraction of total time or bandwidth that needs to be allocated to the relay for best performance is identified. Under a total power constraint, optimal allocation of power between the source and relay is investigated. Finally, bit energy requirements in the low-power regime are studied.
Guidelines for reporting statistics in journals published by the American Physiological Society

Concepts and procedures in statistics are inherent to publications in science. Based on the incidence of standard deviations, standard errors, and confidence intervals in articles published by the American Physiological Society (APS), however, many scientists appear to misunderstand fundamental
Bayesian Spatial Modeling of Housing Prices Subject to a Localized Externality

This work proposes a non stationary random field model to describe the spatial variability of housing prices that are affected by a localized externality. The model allows for the effect of the localized externality on house prices to be represented in the mean function and/or the covariance function of the random field. The correlation function of the proposed model is a mixture of an isotropic correlation function and a correlation function that depends on the distances between home sales and the localized externality. The model is fit using a Bayesian approach via a Markov chain Monte Carlo algorithm. A dataset of 437 single family home sales during 2001 in the city of Cedar Falls, Iowa, is used to illustrate the model.
miRNA-34b Inhibits Prostate Cancer through Demethylation, Active Chromatin Modifications, and AKT Pathways

Purpose: miRNAs can act as oncomirs or tumor-suppressor miRs in cancer. This study was undertaken to investigate the status and role of miR-34b in prostate cancer. Experimental Design: Profiling of miR-34b was carried out in human prostate cancer cell lines and clinical samples by quantitative real-time PCR and in situ hybridization. Statistical analyses were done to assess diagnostic/prognostic potential. Biological significance was elucidated by carrying out a series of experiments in vitro and in vivo . Results: We report that miR-34b is silenced in human prostate cancer and the mechanism is through CpG hypermethylation. miR-34b directly targeted methyltransferases and deacetylases resulting in a positive feedback loop inducing partial demethylation and active chromatin modifications. miR-34b expression could predict overall and recurrence-free survival such that patients with high miR-34b levels had longer survival. Functionally, miR-34b inhibited cell proliferation, colony formation, migration/invasion, and triggered G 0 /G 1 cell-cycle arrest and apoptosis by directly targeting the Akt and its downstream proliferative genes. miR-34b caused a decline in the mesenchymal markers vimentin, ZO1, N -cadherin, and Snail with an increase in E-cadherin expression, thus inhibiting epithelial-to-mesenchymal transition. Finally we showed the antitumor effect of miR-34b in vivo . MiR-34b caused a dramatic decrease in tumor growth in nude mice compared with cont-miR. Conclusion: These findings offer new insight into the role of miR-34b in the inhibition of prostate cancer through demethylation, active chromatin modification, and Akt pathways and may provide a rationale for the development of new strategies targeting epigenetic regulation of miRNAs for the treatment of prostate cancer. Clin Cancer Res; 19(1); 73–84. ©2012 AACR .
BUCKLING BEHAVIOR AND STRUCTURAL EFFICIENCY OF OPEN-SECTION STIFFENED COMPOSITE COMPRESSION PANELS

Several exploratory experiments with /- and blade-stiffened graphite/epoxy panels were conducted to obtain insight into how well experimental data could be correlated with analysis for the buckling behavior of opensection stiffened composite compression panels. Although some nonlinear behavior was observed during the experiments, adequate correlation with analysis was obtained to justify the use of linear, thin-plate buckling analysis in a minimum-weight design synthesis program for J- and blade configurations. Results from two design studies using this program are presented. In the first study the minimum weights of J- and blade-configurations for two different material systems (graphite/epoxy and aluminum) are determined subject to buckling and strength constraints for a wide range of the compressive load index. In the second study the minimum weights required for graphite/epoxy blade-stiffened panels to satisfy additional stiffness constraints typical of mediumsize commercial aircraft wing structures are determined. Both minimum-weight studies indicate that graphite/epoxy open-section stiffened panels can be designed so that weight savings of 30% to 50% are possible compared with the most efficient aluminum designs.
Design of chemical sensor arrays for monitoring disposal sites on the ocean floor

We develop methods for automatic environmental monitoring of disposal sites on the deep ocean floor using chemical sensor arrays and statistical hypothesis testing. Such sites have been proposed to relocate dredge materials from harbors and shipping channels. The transport of pollutants is modeled as a diffusion process, and the measurement and statistical models are derived by exploiting the spatial and temporal evolution of the associated concentration distribution. We derive two detectors, the generalized likelihood ratio (GLR) test and the mean detector and determine their performance in terms of the probabilities of false alarm and detection, The results are applied to the design of chemical sensor arrays satisfying criteria specified in terms of these probabilities, and to optimally select a number of sensors and time samples. Numerical examples are used to demonstrate the applicability of our results.
25th Anniversary Article: Galvanic Replacement: A Simple and Versatile Route to Hollow Nanostructures with Tunable and Well-Controlled Properties

This article provides a progress report on the use of galvanic replacement for generating complex hollow nanostructures with tunable and well-controlled properties. We begin with a brief account of the mechanistic understanding of galvanic replacement, specifically focused on its ability to engineer the properties of metal nanostructures in terms of size, composition, structure, shape, and morphology. We then discuss a number of important concepts involved in galvanic replacement, including the facet selectivity involved in the dissolution and deposition of metals, the impacts of alloying and dealloying on the structure and morphology of the final products, and methods for promoting or preventing a galvanic replacement reaction. We also illustrate how the capability of galvanic replacement can be enhanced to fabricate nanomaterials with complex structures and/or compositions by coupling with other processes such as co-reduction and the Kirkendall effect. Finally, we highlight the use of such novel metal nanostructures fabricated via galvanic replacement for applications ranging from catalysis to plasmonics and biomedical research, and conclude with remarks on prospective future directions.
From artifacts to aggregations: Modeling scientific life cycles on the semantic Web

In the process of scientific research, many information objects are generated, all of which may remain valuable indefinitely. However, artifacts such as instrument data and associated calibration information may have little value in isolation; their meaning is derived from their relationships to each other. Individual artifacts are best represented as components of a life cycle that is specific to a scientific research domain or project. Current cataloging practices do not describe objects at a sufficient level of granularity nor do they offer the globally persistent identifiers necessary to discover and manage scholarly products with World Wide Web standards. The Open Archives Initiative's Object Reuse and Exchange data model (OAI-ORE) meets these requirements. We demonstrate a conceptual implementation of OAI-ORE to represent the scientific life cycles of embedded networked sensor applications in seismology and environmental sciences. By establishing relationships between publications, data, and contextual research information, we illustrate how to obtain a richer and more realistic view of scientific practices. That view can facilitate new forms of scientific research and learning. Our analysis is framed by studies of scientific practices in a large, multidisciplinary, multi-university science and engineering research center, the Center for Embedded Networked Sensing. © 2010 Wiley Periodicals, Inc.
Outside Options and the Failure of the Coase Conjecture

A buyer wishes to purchase a good from a seller who chooses a sequence of prices over time. Each period the buyer can also exercise an outside option, abandoning their search or moving on to another seller. We show there is a unique equilibrium in which the seller charges a constant price in every period equal to the monopoly price, contravening the Coase conjecture. We then embed the singleseller model into a search framework and show the result provides a foundation for the usual “no haggling” assumption. (JEL C78, D42, D43, L12, L13) The Coase conjecture is a cornerstone of modern microeconomic theory, informing monopoly theory and providing a canonical example of the problem of commitment. The idea is that, for any given price, high value buyers are more likely to purchase than low value buyers, leading to negative selection in the demand pool. Accordingly, the seller cuts its price over time, causing high value buyers to delay their purchases. The seller’s inability to commit thus leads its later selves to exert a negative externality on its former selves, reducing its overall profit (Gul, Sonnenschein, and Wilson 1986). This idea of negative selection is robust: versions of it hold when costs are nonlinear (Kahn 1986), when goods depreciate over time (Bond and Samuelson 1984), when there is entry of new buyers (Sobel 1991) and when the buyers face future competition (Fuchs and Skrzypacz 2010). In this article, we show that the Coase conjecture fails in a natural environment where buyers have an outside option they can choose to exercise. We consider a seller who faces a buyer (or a continuum of buyers) with unknown value for the good and unknown outside option. Each period, the seller chooses price p t ; the buyer then chooses to buy, wait, or exercise his option and terminate the game. The outside option may come from the possibility of buying another product. For example, when waiting for the price of the iPhone to fall, a customer could instead buy a comparable phone from a competitor. Similarly, when bargaining over the price of a car, a buyer may abandon negotiations and move on to the next dealer. The outside option may also come from pursuing other objectives once the negotiation has terminated. For example, after he finishes bargaining at a bazaar, a tourist could start seeing local attractions.
The trustworthy digital camera: restoring credibility to the photographic image

The trustworthy digital camera is an application of existing technology toward the solution of an evermore-troubling social problem, the eroding credibility of the photographic image. Although it will always be possible to lie with a photograph (using such time-honored techniques as false perspective and misleading captions), this proposed device will prevent the explosion of very capable personal computers from driving up the incidence of doctored photographs being passed off as truth. A solution to this problem comes from the proposed digital signature standard (DSS), which incorporates modern cryptographic techniques to authenticate electronic mail messages. >
MR Imaging of the Glenohumeral Ligaments

The glenohumeral ligaments, particularly the inferior one, are the major passive stabilizers of the joint, and the labrum functions as a site of ligamentous attachment. The strong union between the collagen fibers of the glenohumeral ligaments and the glenoid labrum is more resistant to injury than the union between the glenoid rim and the labrum. Labral tears associated with glenohumeral instability are therefore usually secondary to avulsion rather than impaction. This article reviews the normal MR imaging anatomy, variants and pitfalls of the glenohumeral ligaments, and the basic biomechanics of the glenohumeral ligaments. Examples of injuries involving these structures are provided.
Bacterial death comes full circle: targeting plasmid replication in drug-resistant bacteria

It is now common for bacterial infections to resist the preferred antibiotic treatment. In particular, hospital-acquired infections that are refractory to multiple antibiotics and ultimately result in death of the patient are prevalent. Many of the bacteria causing these infections have become resistant to antibiotics through the process of lateral gene transfer, with the newly acquired genes encoding a variety of resistance-mediating proteins. These foreign genes often enter the bacteria on plasmids, which are small, circular, extrachromosomal pieces of DNA. This plasmid-encoded resistance has been observed for virtually all classes of antibiotics and in a wide variety of Gram-positive and Gram-negative organisms; many antibiotics are no longer effective due to such plasmid-encoded resistance. The systematic removal of these resistance-mediating plasmids from the bacteria would re-sensitize bacteria to standard antibiotics. As such, plasmids offer novel targets that have heretofore been unexploited clinically. This Perspective details the role of plasmids in multi-drug resistant bacteria, the mechanisms used by plasmids to control their replication, and the potential for small molecules to disrupt plasmid replication and re-sensitize bacteria to antibiotics. An emphasis is placed on plasmid replication that is mediated by small counter-transcript RNAs, and the "plasmid addiction" systems that employ toxins and antitoxins.
Toward a Comparative Economics of Plea Bargaining

We attempt to open a path to the comparative analysis of criminal procedure by superimposing the efficiency principle onto an adversarial system characterized by an aversion to false convictions and an inquisitorial system characterized by a desire to justly punish the guilty. We begin with a general model of plea bargaining, embed it in a larger framework that addresses the costs of adjudication, the value of punishing the guilty and the costs of false convictions, and then link the desirability of plea bargaining and compulsory prosecution to the weights given these costs and benefits in the objective function. We examine the judicial endorsement of plea bargaining in the United States and the debate over European analogs to plea bargaining in light of the model, and conclude that plea bargaining will increase social welfare in adversarial systems but not in inquisitorial ones.
Taxing Consumption and Other Sins

taxes as their primary tools to collect revenue. In the rest of the world, governments also use income and payroll taxes, but rely much more heavily than does the United States on taxing consumption. Consumption taxes take many forms, including general sales taxes, value-added taxes, and excise taxes on the consumption of specific items including gasoline, alcohol, tobacco products, firearms, air travel, telephone communication, and others. The U.S. government does not use a value-added tax, making the United States unique among high-income countries and a rarity in the larger world. As of 2004, at least 134 countries rely on value-added taxes as a substantial source of funding. Value-added taxes are sophisticated forms of sales taxes in which taxes are withheld by businesses according to value added at every stage of production. American states do impose sales taxes on broad categories of consumer purchases, but state governments are considerably smaller than national governments, and their sales tax rates are very low compared to the value-added tax rates used in the rest of the world. The United States also imposes unusually low excise taxes even after controlling for total tax collections, which are lower in the United States than they are in most high-income countries. The deliberate social engineering that underlies the selection of certain commodities for unusually high rates of taxation appeals less to Americans than to residents of other countries. Moreover, the "sin" taxes on
Nitrogen sources and cycling in the San Francisco Bay estuary: A nitrate dual isotopic composition approach

We used the dual isotopic composition of nitrate (δ15N and δ18O) within the estuarine system of San Francisco (SF) Bay, California, to explore the utility of this approach for tracing sources and cycling of nitrate (NO2−). Surface water samples from 49 sites within the estuary were sampled during July–August 2004. Spatial variability in the isotopic composition suggests that there are multiple sources of nitrate to the bay ecosystem including seawater, several rivers and creeks, and sewage effluent. The spatial distribution of nitrate from these sources is heavily modulated by the hydrodynamics of the estuary. Mixing along the estuarine salinity gradient is the main control on the spatial variations in isotopic composition of nitrate within the northern arm of SF Bay. However, the nitrate isotopic composition in the southern arm of SF Bay exhibited a combination of source mixing and phytoplankton drawdown due mostly to the long residence time during the summer study period. Very low δ18ONO3 values (as low as −5.0%) at the Sacramento–San Joaquin River delta region give rise to a wide range of δ18ONO3 values in the SF Bay system. The range in δ18ONO3 values is more than twice that of δ15NNO3, suggesting that δ18ONO3 is an even more sensitive tool for tracing nitrate sources and cycling than δ15NNO3.
Injuries from the 2002 North Carolina ice storm, and strategies for prevention

Summary Context: In 2002, an ice storm interrupted power to 1.3 million households in North Carolina, USA. Previous reports described storm injuries in regions with frequent winter weather. [Blindauer KM, Rubin C, Morse DL, McGeehin M. The 1996 New York blizzard: impact on noninjury visits. Am J Emerg Med 1999;17(1):23–7; Centers for Disease Control and Prevention. Community needs assessment and morbidity surveillance following an ice storm—Maine, January 1998. MMRW 1998;47(17):351–5; Daley WR, Smith A, Paz-Argandona E, Malilay J, McGeehin M. An outbreak of carbon monoxide poisoning after a major ice storm in Maine. J Emerg Med 2000;18(1):87–93; Hamilton J. Quebec's ice storm’98: “all cards wild, all rules broken” in Quebec's shell-shocked hospitals. Can Med Assoc J 1998;158(4):520–4; Hartling L, Brison RJ, Pickett W. Cluster of unintentional carbon monoxide poisonings presenting to the emergency departments in Kingston, Ontario during ‘Ice Storm 98’. Can J Public Health 1998;89(6):388–90; Hartling L, Pickett W, Brison RJ. The injury experience observed in two emergency departments in Kingston, Ontario during ‘ice storm 98’. Can J Public Health 1999;90(2):95–8; Houck, PM, Hampson NB. Epidemic carbon monoxide poisoning following a winter storm. J Emerg Med 1997;15(4):469–73; Lewis LM, Lasater LC. Frequency, distribution, and management of injuries due to an ice storm in a large metropolitan area. South Med J 1994;87(2):174–8; Smith RW, Nelson DR. Fractures and other injuries from falls after an ice storm. Am J Emerg Med 1998;16(1):52–5]. We postulated that injuries might differ in a region where ice storms are less common. Objective: Identify storm-related injuries. Design: Emergency department (ED) charts from the storm period (defined as onset of precipitation until 99% power restoration) were retrospectively reviewed. Included injuries were: falls on ice; injuries due to darkness; cold exposure; injuries from storm-related damage; burns; or carbon monoxide/smoke exposure. Setting: Tertiary care ED, central North Carolina. Patients: All ED patients. Interventions: None. Main outcome measures: Mechanism of injury. Results: One hundred thirty incidents occurred, most resulting from storm damage and carbon monoxide. Seven were life threatening: four spinal fractures and two intracranial hemorrhages from falling tree limbs and one hypothermia. Carbon monoxide poisoning affected one pregnant woman and all children in our series. Twenty three percent of patients were Hispanic, although Hispanics comprise only 11% of the study ED population. Conclusions: Injuries from storm-related damage and carbon monoxide exposure predominated. Available hyperbaric chambers were quickly filled to capacity. Hispanics experienced a disproportionate number of injuries.
Organizations, Regulation, and Economic Behavior: Regulatory Dynamics and Forms from the Nineteenth to Twenty-First Century

Current scholarship suggests that instead of fueling deregulation and a race to the bottom, globalization and neoliberalism often go hand in hand with the expansion of regulatory rules and agents. We survey efforts to address this paradox. Building on analyses of nineteenth- and twentieth-century regulation, research on the current period has produced two critical analytical advances. It has developed new, multilevel conceptions of globalization, international interdependence, and their effects on regulation. Moreover, in grappling with new regulatory experiments, research has moved beyond command and control to reconceptualize regulation as an institutional form. Yet in its haste to understand the new century, this research has barely begun to produce systematic analyses of whether and how new forms are translated into practice and shape organizational behavior. It also assumes discontinuity between new forms and their bureaucratic predecessors, leaving unexplored how concepts developed for the new centu...
Classification of simple C*-algebras and higher dimensional noncommutative tori

We show that unital simple C ∗ -algebras with tracial topological rank zero which are locally approximated by subhomogeneous C ∗ -algebras can be classified by their ordered K-theory. We apply this classification result to show that certain simple crossed products are isomorphic if they have the same ordered K-theory. In particular, irrational higher dimensional noncommutative tori of the form C( k ) ×θ are in fact inductive limits of circle algebras.
Polar Motion Spectra Based upon Doppler, IPMS and BIH Data

In comparing polar motion spectra, an oscillation was found at 1.3 cpy which might be due to an Eulerian motion of the solid inner core. An extended 15-year data set was filtered and analyzed to yield a Chandler peak with a period 430.8 solar days and a full width at half-maximum of 0.7 days (Q-600). The data was reanalyzed in overlapping 3-year segments and indicates that the excitation of the Chandler wobble is a discrete process and that periods as long as three years occur in which the driving mechanism is essentially quiescent.
The Role of three-center/four-electron Bonds in Superelectrophilic Dirhodium Carbene and Nitrene Catalytic Intermediates

Three-center/four-electron (3c/4e) bonds are important bonding motifs that dictate the electronic structure, and thereby the reactivity, of metal–metal bonded carbene and nitrene intermediate complexes that are crucial to the dirhodium-catalyzed functionalization of hydrocarbons. In this Perspective article, general features of the 3c/4e bond are presented and discussed in comparison to two-center/two-electron (2c/2e) bonds. Specifically, 3c/4e bonding interactions lead to longer distances between the atoms involved and measurably weaker bonds. Additionally, excited states derived from the 3c/4e bonding manifold are lower in energy than those derived from a 2c/2e manifold, signifying a greater degree of reactivity in the former case. Three coterminous 3c/4e Ru–Ru–N bonds are present in metal–metal/metal–ligand multiply bonded diruthenium terminal nitrido compounds. This bonding situation results in an unusual superelectrophilic character of the nitride nitrogen atom, exemplified by its insertion into aryl C–H bonds via an electrophilic aromatic substitution mechanism. The key catalytic intermediates in dirhodium-catalyzed C–H functionalization reactions, dirhodium carbene and dirhodium nitrene complexes, may also be described as superelectrophilic by virtue of 3c/4e Rh–Rh–C(or N) σ and π bonds. These 3c/4e bonding interactions set apart dirhodium carbene and nitrene intermediates from other, less electrophilic, carbene or nitrene species.
Money and Income: Post Hoc Ergo Propter Hoc?

An ultra-Keyniesian model, 303. — A Friedman model, 310. — Comparisons of timing implications, 314.
On the physico-chemical characterization of monoamine oxidase (MAO) as a basis for the study of its role in physiological and pathological processes.

Publisher Summary This chapter discusses the physico-chemical characterization of monoamine oxidase (MAO) as a basis for the study of its role in physiological and pathological processes. MAO affects the reaction rates of several other components and, thus, influences the biological action of monoamines. The rate of MAO itself is the resultant of a long list of parameters such as the rates of substrate transfer to the enzyme through the outer mitochondrial membrane and the chemical nature and geometry of the enzyme and of the substrates. If the two substrates, oxygen and amine, form ternary complexes with MAO, then some substrate properties determine the affinity of MAO for oxygen and thus again the overall reaction rate in situations of low oxygen tension. As MAO inhibitors have become such important investigative tools, their mode of action needs to be understood that in turn requires substantial information about the enzyme–substrate interaction.
A random tunnel number one 3–manifold does not fiber over the circle

We address the question: how common is it for a 3‐manifold to fiber over the circle? One motivation for considering this is to give insight into the fairly inscrutable Virtual Fibration Conjecture. For the special class of 3‐manifolds with tunnel number one, we provide compelling theoretical and experimental evidence that fibering is a very rare property. Indeed, in various precise senses it happens with probability 0. Our main theorem is that this is true for a measured lamination model of random tunnel number one 3‐manifolds. The first ingredient is an algorithm of K Brown which can decide if a given tunnel number one 3‐manifold fibers over the circle. Following the lead of Agol, Hass and W Thurston, we implement Brown’s algorithm very efficiently by working in the context of train tracks/interval exchanges. To analyze the resulting algorithm, we generalize work of Kerckhoff to understand the dynamics of splitting sequences of complete genus 2 interval exchanges. Combining all of this with a “magic splitting sequence” and work of Mirzakhani proves the main theorem. The 3‐manifold situation contrasts markedly with random 2‐generator 1‐relator groups; in particular, we show that such groups “fiber” with probability strictly between 0 and 1.
New Zinc-bis(Dialkylamides) Potentially Usable as Site-Selective Dopants for p-Type ZnSe

Abstract : In earlier work, the effective utilization of Zn(NSi(CH3)32)2 as a site-selective dopant for the production of p-type ZnSe by OMVPE was demonstrated. Several new zinc-bis(dialkylamides) of the general form (R)(R') nznN(R )(R ') now have been prepared. They have been characterized by 1H- and 13C-NMR, GC/MS and elemental analysis. Vapor pressures and gas phase decomposition profiles have been examined. Correlations of vapor pressure and structure are discussed for this series of compounds. A mechanism for the site- selectivity observed in the incorporation of nitrogen is proposed.
Index assignment for multichannel communication under failure

We consider the problem of constructing multiple description scalar quantizers and describing the achievable rate-distortion tuples in that setting. We model this as a combinatorial optimization problem of number arrangements in a matrix. This approach gives a general technique for deriving lower bounds on the distortion at given channel rates. This technique is constructive, thus allowing an algorithm that gives an upper bound. For the case of two communication channels with equal rates, the bounds coincide, thus giving the precise lowest achievable distortion at fixed rates. The bounds are within a small constant for a higher number of channels. To the best of our knowledge, this is the first result involving systems with more than two communication channels.
Generalized variables for controlling Government Transfer Services with respect to performance measures

The term Government Transfer Services is used in reference to any of the organized streams of public resources that flow into private economic activity. This includes such activities as offshore leasing, Social Security, and NASA technology transfer services. This paper describes a performance measure, empirical results, a theory, and a control model for such services. These are illustrated by a specific example (NASA). An agenda for developing this service control method is also presented.
Enzymatic asymmetrization of meso-2-cycloalken--1,4-diols and their diacetates in organic and aqueous media

Abstract meso-2-Cycloalken-1,4-diols or the corresponding diacetates with five-, six-, and seven-membered rings were subjected to enzymatic asymmetrizations utilizing a recombinant version of lipase B from Candida antarctica (Novo SP-435) in organic or aqueous media.
Regiospecific preparation of α,α-dihalofluoromethyl perfluoroalkyl ketones via halogenation of perfluoro betaines

Abstract Acylation of fluorinated phosphoranium salts with perfluorinated acyl chlorides providedthe corresponding ( Z )-perfluoro betaines in high yield. Subsequent chlorination or brominationof the betaines regiospecifically yields the α,α-dihalofluoromethyl perfluoroalkylketones. Halogen specificity is best controlled via use of CFCl 3 /Cl 2 for the preparationof dichloroketones and CFBr 3 /Br 2 for the corresponding dibromoketones. The dihalophosphoraneby-product can promote a halogen-exchange reaction with ketones.
Tests of CPT and lorentz symmetry using hydrogen and noble gas masers

I will describe the use of hydrogen and noble gas masers to make the most sensitive tests to date of CPT and Lorentz symmetry for the proton and the neutron
Chemistry of Vibronic Coupling, Part 4: Off-Diagonal Vibronic Coupling Constants Across the Periodic Table

Vibronic coupling for inter–valence charge–transfer states in linear symmetric ABA molecules (A, B = s–, p– or d–block element) is investigated computationally. In particular we examine vibronic coupling as a function of the s, p, d – block nature of the A and B constituent elements. Based on density-functional theory computations for 395 triatomic molecules, we construct a map of a vibronic stability parameter G (defined as the ratio of asymmetric to symmetric stretching force constants) across the periodic table. Correlations of G versus the sum and difference of electronegativities of A and B elements are tested, and also vs. a useful parameter f, the ratio of the sum of electronegativities to an AB separation. Usually, the larger the sum of electronegativities, and the shorter the AB bond, the larger the vibronic instability. The largest vibronic instability thus occurs for interhalogen compounds. Molecules containing d-block elements exhibit trends similar to those of molecules built of p-block elements with similar electronegativities, although the latter are usually more unstable. A molecular orbital model is developed to explain the trends obtained in our computations, as well as to build a framework for systematic manipulation of vibronic coupling constants in molecular systems. From the model we argue that vibronic coupling is usually strongest in systems built of hard Lewis acids and bases. We also show that s–p mixing and “ionic/covalent curve crossing” increase the vibronic instability of a molecule. To attain high vibronic instability, one should build a molecule of light, highly electronegative p–block elements. These findings may be of use in the experimental search for new superconducting materials.
Theory of electron-phonon dynamics in insulating nanoparticles

We discuss the rich vibrational dynamics of nanometer-scale semiconducting and insulating crystals as probed by localized electronic impurity states, with an emphasis on nanoparticles that are only weakly coupled to their environment. Two principal regimes of electron-phonon dynamics are distinguished, and a brief survey of vibrational-mode broadening mechanisms is presented. Recent work on the effects of mechanical interaction with the environment is discussed.
Texture classification by wavelet packet signatures

This correspondence introduces a new approach to characterize textures at multiple scales. The performance of wavelet packet spaces are measured in terms of sensitivity and selectivity for the classification of twenty-five natural textures. Both energy and entropy metrics were computed for each wavelet packet and incorporated into distinct scale space representations, where each wavelet packet (channel) reflected a specific scale and orientation sensitivity. Wavelet packet representations for twenty-five natural textures were classified without error by a simple two-layer network classifier. An analyzing function of large regularity (D/sub 20/) was shown to be slightly more efficient in representation and discrimination than a similar function with fewer vanishing moments (D/sub 6/) In addition, energy representations computed from the standard wavelet decomposition alone (17 features) provided classification without error for the twenty-five textures included in our study. The reliability exhibited by texture signatures based on wavelet packets analysis suggest that the multiresolution properties of such transforms are beneficial for accomplishing segmentation, classification and subtle discrimination of texture. >
Don't Stand So Close to Me: Spatial Contagion Effects and Party Competition

In this article, we bring together elements from the literatures on economic voting and spatial voting to gain theoretical leverage on the combined role of clarity of responsibility, party policy positions, and economic performance in elections. Building on evidence of voter knowledge, we develop a theory of spatial contagion effects to explain how factors drawn from both of these literatures combine to shape changes in support for political parties. We test this theory with a spatial autoregressive model of party competition in 23 nations from 1951 to 2005. As expected, we find evidence of strong spatial contagion effects in elections with low clarity of responsibility.
UV Lithographic Patterning on Spin-coated DNA Thin-films

Photopatterning with 266 nm UV light was accomplished on spin-coated DNA thin films using two different techniques. Lithographic masks were used to create 10-100 micron-sized arrays of enhanced hydrophilicity. Two such masks were used: (1) Polka Dot Filter having opaque squares and a transparent grid and (2) A metal wire-mesh having transparent squares and opaque grid. UV light selectively photodissociates the DNA film where it is exposed into smaller more hydrophilic fragments. UV-exposed films are then coated with a solution of a protein. The protein appears to selectively coat over areas exposed to UV light. We have also used interferometric lithography with UV light to accomplish patterning on the scale of 1 micron on DNA thin films. This technique has the potential to generate micro/nano arrays and vary the array-size. This paper describes the fabrication of these microarrays and a plausible application for fabricating antibody arrays for protein sensing applications.
The Tale of Three Amigos: Remittances, Exchange Rates, and Money Demand in Mexico

The author analyzes the relationship between remittances, exchange rates, and money demand in Mexico. He finds that shocks to remittances have a positive impact on domestic money demand. The results also suggest the existence of a bi-directional relationship between remittances and the exchange rate. Furthermore, positive shocks to remittances are found to have a negative impact on Mexico's real exchange rate. This indicates that remittances appreciate the Mexican peso and therefore may impact on the competitiveness of the tradable sector negatively.
Optimal Dynamic Mechanism Design and the Virtual-Pivot Mechanism

We consider the problem of designing optimal mechanisms for settings where agents have dynamic private information. We present the virtual-pivot mechanism, which is optimal in a large class of environments that satisfy a separability condition. The mechanism satisfies a rather strong equilibrium notion (it is periodic ex post incentive compatible and individually rational). We provide both necessary and sufficient conditions for immediate incentive compatibility for mechanisms that satisfy periodic ex post incentive compatibility in future periods. The result also yields a strikingly simple mechanism for selling a sequence of items to a single buyer. We also show that the allocation rule of the virtual-pivot mechanism has a very simple structure (a virtual index) in multiarmed bandit settings. Finally, we show through examples that the relaxation technique we use does not produce optimal dynamic mechanisms in general nonseparable environments.
An accessible method of hiding HTML content

Though somewhat rare, there are occasions when the accessibility needs of screen reader users appear to be at odds with the needs of visual users. This kind of conflict occurs when Web developers put form elements inside of a data table matrix, when they want to use images as headings instead of text, and in other situations. Adding extra text helps screen reader users, but can complicate the visual layout, thus reducing understandability. One solution is to use CSS (Cascading Style Sheets) to hide the text from sighted users in a way that is still accessible to screen readers. The details of this technique are discussed, along with the technical reasoning behind it.
Nonblocking WDM switching networks with full and limited wavelength conversion

In previous years, with the rapid exhaustion of the capacity in wide area networks led by Internet and multimedia applications, demand for high bandwidth has been growing at a very fast pace. Wavelength-division multiplexing (WDM) is a promising technique for utilizing the huge available bandwidth in optical fibers. We consider efficient designs of nonblocking WDM permutation switching networks. Such designs require nontrivial extensions from the existing designs of electronic switching networks. We first propose several permutation models in WDM switching networks ranging from no wavelength conversion, to limited wavelength conversion, to full wavelength conversion, and analyze the network performance in terms of the permutation capacity and network cost, such as the number of optical cross-connect elements and the number of wavelength converters required for each model. We then give two methods for constructing nonblocking multistage WDM switching networks to reduce the network cost.
Assessing difference: examining Florida’s initial teacher preparation programs and exploring alternative specifications of value-added models

This study explores important statistical issues on the appropriate functional form and model specification of the value-added educational achievement equation. We also wish to estimate the causal effect of a teacher's institution of academic preparation and pedagogical training. Standardized test scores, viz., the Florida Comprehensive Assessment Tests (FCAT), provide a measure of pupil academic achievement. Accordingly, this study uses a value-added regression model to establish whether there is a "college preparation effect" on the average pupil's FCAT reading and mathematics scores. We find that value-added regression analysis fails to uncover robust and substantive college preparation effects. Regardless of race (African American, Hispanic, or white), male or female status, or FCAT mathematics versus FCAT reading, pupil academic achievement does not vary substantively according to a teacher's college of preparation. Further, the statistical significance of teacher program effects also depends on the functional form and specification of the value-added model.
Subtalar arthrodesis with internal compression for post-traumatic arthritis

We studied retrospectively the results in 24 patients (25 feet) who had been treated by subtalar arthrodesis with internal compression for post-traumatic arthritis from 1988 to 1992. Fifteen patients were men (16 feet) and nine (9 feet) were women. Their mean age was 43 years (22 to 68), and the average duration of follow-up was four years (2 to 6). A single compression screw was used in all feet and iliac-crest bone grafting in ten. Union was achieved in 24 of the 25 feet (96%). Based on a clinical scale the results were excellent in 10 feet, good in 7, fair in 6, and poor in 2 and on the Angus and Cowell score they were good in 19 feet, fair in 4, and poor in 2. The two poor results were due to nonunion in one patient and reflex sympathetic dystrophy in the other. One reoperation was performed for nonunion. Eighteen patients (18 feet) were satisfied with the results, four were satisfied with reservations, and three were dissatisfied. Progressive ankle and midfoot arthritis did not occur in the absence of pre-existing degenerative changes in these joints. We conclude that isolated subtalar arthrodesis with internal compression was effective treatment for post-traumatic subtalar arthritis. Iliac-crest bone grafting was not routinely required.
Mechanistic Home Range Models and Resource Selection Analysis: A Reconciliation and Unification

In the three decades since its introduction, resource selection analysis (RSA) has become a widespread method for analyzing spatial patterns of animal relocations obtained from telemetry studies. Recently, mechanistic home range models have been proposed as an alternative framework for studying patterns of animal space-use. In contrast to RSA models, mechanistic home range models are derived from underlying mechanistic descriptions of individual movement behavior and yield spatially explicit predictions for patterns of animal space-use. In addition, their mechanistic underpinning means that, unlike RSA, mechanistic home range models can also be used to predict changes in space-use following perturbation. In this paper, we develop a formal reconciliation between these two methods of home range analysis, showing how differences in the habitat preferences of individuals give rise to spatially explicit patterns of space-use. The resulting unified framework combines the simplicity of resource selection analysis with the spatially explicit and predictive capabilities of mechanistic home range models.
Microfabricated gas chromatograph for Sub-ppb determinations of TCE in vapor intrusion investigations

Abstract A microfabricated gas chromatograph ( μ GC ) is described and its application to the analysis of sub-parts-per-billion (ppb) concentrations of trichloroethylene (TCE) in mixtures, relevant to the problem of TCE vapor intrusion (VI) into homes and offices, is demonstrated. The system employs a MEMS focuser, dual MEMS separation columns, and MEMS interconnects along with a microsensor array. These are interfaced to a (non-MEMS) front-end pre-trap and high-volume sampler module to reduce analysis time. The response patterns generated from the sensor array for each vapor are combined with the chromatographic retention time to identify and differentiate the components of VOC mixtures. All functions are controlled by a LabView routine written in house. A chemometric method based on multivariate curve resolution has also been developed for analyzing partially resolved mixture components. First results are presented of the capture, separation, recognition, and quantification of TCE in a mixture. TCE is measured at 0.185 ppb, with a projected detection limit of 0.030 ppb (20-L sample).