cssi/SciSciGPT-SciSciNet huggingface dataset:
A model and architecture for pseudo-random generation with applications to /dev/random

We present a formal model and a simple architecture for robust pseudorandom generation that ensures resilience in the face of an observer with partial knowledge/control of the generator's entropy source. Our model and architecture have the following properties:Resilience. The generator's output looks random to an observer with no knowledge of the internal state. This holds even if that observer has complete control over data that is used to refresh the internal state.Forward security. Past output of the generator looks random to an observer, even if the observer learns the internal state at a later time.Backward security/Break-in recovery. Future output of the generator looks random, even to an observer with knowledge of the current state, provided that the generator is refreshed with data of sufficient entropy.Architectures such as above were suggested before. This work differs from previous attempts in that we present a formal model for robust pseudo-random generation, and provide a formal proof within this model for the security of our architecture. To our knowledge, this is the first attempt at a rigorous model for this problem.Our formal modeling advocates the separation of the entropy extraction phase from the output generation phase. We argue that the former is information-theoretic in nature, and could therefore rely on combinatorial and statistical tools rather than on cryptography. On the other hand, we show that the latter can be implemented using any standard (non-robust) cryptographic PRG.We also discuss the applicability of our architecture for applications such as /dev/(u)random in Linux and pseudorandom generation on smartcards.
Submodular maximization meets streaming: matchings, matroids, and more

We study the problem of finding a maximum matching in a graph given by an input stream listing its edges in some arbitrary order, where the quantity to be maximized is given by a monotone submodular function on subsets of edges. This problem, which we call maximum submodular-function matching (MSM), is a natural generalization of maximum weight matching (MWM), which is in turn a generalization of maximum cardinality matching. We give two incomparable algorithms for this problem with space usage falling in the semi-streaming range--they store only $$O(n)$$O(n) edges, using $$O(n\log n)$$O(nlogn) working memory--that achieve approximation ratios of 7.75 in a single pass and $$(3+\varepsilon )$$(3+?) in $$O(\varepsilon ^{-3})$$O(?-3) passes respectively. The operations of these algorithms mimic those of Zelke's and McGregor's respective algorithms for MWM; the novelty lies in the analysis for the MSM setting. In fact we identify a general framework for MWM algorithms that allows this kind of adaptation to the broader setting of MSM. Our framework is not specific to matchings. Rather, we identify a general pattern for algorithms that maximize linear weight functions over "independent sets" and prove that such algorithms can be adapted to maximize a submodular function. The notion of independence here is very general; in particular, appealing to known weight-maximization algorithms, we obtain results for submodular maximization over hypermatchings in hypergraphs as well as independent sets in the intersection of multiple matroids.
Employment-Based Health Benefits: Recent Trends and Future Outlook:

The employment-based health benefits system established its roots many years ago. It was during World War II that many more employers began to offer health benefits. Recently, however, both the percentage of workers with employment-based health benefits and the comprehensiveness of such coverage have been declining. This paper examines recent trends in employment-based health benefits. It also considers the likely future of this important workplace benefit in light of shifts from defined benefit to defined contribution models of employee benefits and with regard to the implementation of health reform.
Fluorescent nucleotides: synthesis and characterization.

Publisher Summary The purpose of this chapter is to provide information on the fluorescent nucleotides. A proper characterization of fluorescent nucleotides requires reporting of the absorption spectrum and molar extinction coefficient. Molar extinction coefficients are useful because the exact mass of many nucleotide preparations is not known. Fluorescent nucleotides are widely used to study the structure and function of proteins and nucleic acids. With the advent of methods to study macromolecules at the single-molecule level with fluorescence imaging techniques, and the advent of two-photon excitation technologies, the interest in new nucleofide derivatives with appropriate fluorescent properties has increased. Basic information about the general approaches to synthesis such as reagent preparation, monitoring of synthetic reactions, chromatographic methods, spectral characterization, and compositional analysis are provided in the chapter to prepare new compounds. The general classes of nucleotide derivatives are also summarized and general synthetic routes are described in the chapter. Specific protocols are provided only when the synthesis demonstrates a route to a general class of compounds.
Synthesis of (1R)-(+)-nopinone- and (1S)-(−)-verbenone-derived chiral annulated indenes via electrocyclic reactions

Abstract Two new chiral annulated indene derivatives have been stereoselectively synthesized via acid-catalyzed electrocyclic reactions from naturally occurring homochiral precursors (1 R )-(+)-nopinone and (1 S )-(−)-verbenone.
An empirical model of decadal ENSO variability

This paper assesses potential predictability of decadal variations in the El Nino/Southern Oscillation (ENSO) characteristics by constructing and performing simulations using an empirical nonlinear stochastic model of an ENSO index. The model employs decomposition of global sea-surface temperature (SST) anomalies into the modes that maximize the ratio of interdecadal-to-subdecadal SST variance to define low-frequency predictors called the canonical variates (CVs). When the whole available SST time series is so processed, the leading canonical variate (CV-1) is found to be well correlated with the area-averaged SST time series which exhibits a non-uniform warming trend, while the next two (CV-2 and CV-3) describe secular variability arguably associated with a combination of Atlantic Multidecadal Oscillation (AMO) and Pacific Decadal Oscillation (PDO) signals. The corresponding ENSO model that uses either all three (CVs 1–3) or only AMO/PDO-related (CVs 2 and 3) predictors captures well the observed autocorrelation function, probability density function, seasonal dependence of ENSO, and, most importantly, the observed interdecadal modulation of ENSO variance. The latter modulation, and its dependence on CVs, is shown to be inconsistent with the null hypothesis of random decadal ENSO variations simulated by multivariate linear inverse models. Cross-validated hindcasts of ENSO variance suggest a potential useful skill at decadal lead times. These findings thus argue that decadal modulations of ENSO variability may be predictable subject to our ability to forecast AMO/PDO-type climate modes; the latter forecasts may need to be based on simulations of dynamical models, rather than on a purely statistical scheme as in the present paper.
Design Methodology for a Very High Frequency Resonant Boost Converter

This paper introduces a design methodology for a resonant boost converter topology that is suitable for operation at very high frequencies. The topology we examine features a low parts count and fast transient response, but suffers from higher device stresses compared to other topologies that use a larger number of passive components. A numerical design procedure is developed for this topology that does not rely on time-domain simulation sweeps across parameters. This allows the optimal converter design to be found for a particular main semiconductor switch. If an integrated power process is used where the designer has control over layout of the semiconductor switch, the optimal combination of converter design and semiconductor layout can be found. To validate the proposed converter topology and design approach, a 75-MHz prototype converter is designed and experimentally demonstrated. The performance of the prototype closely matches that predicted by the design procedure, and the converter achieves good efficiency over a wide input voltage range.
Natural product glycorandomization.

Glycorandomization is a chemoenzymatic strategy that overcomes the limitations in natural product derivatization associated with both solely chemistry-based approaches or in vivo engineering. In this article we present the basic strategies for glycorandomization development as a next-generation tool in drug discovery.
Chemical synthesis gets a fillip from molecular recognition and self-assembly processes

By drawing on nature conceptually, the practice of chemical synthesis can now be broadened in scope to include the supramolecular synthesis of supermolecules and their postassembly covalent modification to form mechanically interlocked molecules, which the chemist can use to build functioning nanosystems after the style of those found in the living world.
Adaptation, Clonal Interference, and Frequency-Dependent Interactions in a Long-Term Evolution Experiment with Escherichia coli

Twelve replicate populations of Escherichia coli have been evolving in the laboratory for >25 years and 60,000 generations. We analyzed bacteria from whole-population samples frozen every 500 generations through 20,000 generations for one well-studied population, called Ara−1. By tracking 42 known mutations in these samples, we reconstructed the history of this population’s genotypic evolution over this period. The evolutionary dynamics of Ara−1 show strong evidence of selective sweeps as well as clonal interference between competing lineages bearing different beneficial mutations. In some cases, sets of several mutations approached fixation simultaneously, often conveying no information about their order of origination; we present several possible explanations for the existence of these mutational cohorts. Against a backdrop of rapid selective sweeps both earlier and later, two genetically diverged clades coexisted for >6000 generations before one went extinct. In that time, many additional mutations arose in the clade that eventually prevailed. We show that the clades evolved a frequency-dependent interaction, which prevented the immediate competitive exclusion of either clade, but which collapsed as beneficial mutations accumulated in the clade that prevailed. Clonal interference and frequency dependence can occur even in the simplest microbial populations. Furthermore, frequency dependence may generate dynamics that extend the period of coexistence that would otherwise be sustained by clonal interference alone.
Solid-state and biological systems interface

Solid-state electronic devices can be engineered to detect and manipulate biological molecules and cells by using electric or magnetic interactions. The integrated circuits, which can contain a large number of such devices, may then potentially be developed into low-cost chip-scale platforms to perform bioanalytical tasks in a multiplexed manner for applications in biology, biotechnology, and personalized medicine. This paper reviews some recent developments in this solid-state electronic and biological systems interface.
Neural network-based sensor signal accelerator

A strategy has been developed to computationally accelerate the response time of a generic electronic sensor. The strategy can be deployed as an algorithm in a control system or as a physical interface (on an embedded microcontroller) between a slower responding external sensor and a higher-speed control system. Optional code implementations are available to adjust algorithm performance when computational capability is limited. In one option, the actual sensor signal can be sampled at the slower rate with adaptive linear neural networks predicting the sensor's future output and interpolating intermediate synthetic output values. In another option, a synchronized collection of predictors sequentially controls the corresponding synthetic output voltage. Error is adaptively corrected in both options. The core strategy has been demonstrated with automotive oxygen sensor data. A prototype interface device is under construction. The response speed increase afforded by this strategy could greatly offset the cost of developing a replacement sensor with a faster physical response time.
Semantic web infrastructure for fungal enzyme biotechnologists

The FungalWeb Ontology seeks to support various data integration needs of enzyme biotechnology from inception to product roll. Serving as a knowledgebase for decision support, the conceptualization seeks to link fungal species with enzymes, enzyme substrates, enzyme classifications, enzyme modifications, enzyme related intellectual property, enzyme retail and applications. The ontology, developed in the OWL language, is the result of the integration of numerous biological database schemas, web accessible text resources and components of existing ontologies. We assess the quantity of implicit knowledge in the FungalWeb Ontology by analyzing the range of tags in the OWL files and along with other description logic (DL) computable metrics of the ontology, contrast it with other publicly available bio-ontologies. Thereafter, we demonstrate how the FungalWeb Ontology supports its broad remit required in fungal biotechnology by (i) presenting application scenarios (ii) presenting the conceptualizations of the ontological frame able to support these scenarios and (iii) suggesting semantic queries typical of a fungal enzymologist involved in product development. Recognizing the complexity of the ontology query process for the non-technical manager we introduce a simplified query tool, Ontoligent Interactive Query (OntoIQ) that allows the user to browse and build queries from a selection of query patterns and ontology content. The OntoIQ interface supports users not familiar with writing DL syntax allowing them access to the ontology with expressive description logic reasoning tools. Finally we discuss the challenges encountered during the development of semantic infrastructure for fungal enzyme biotechnologists.
Palladium-Catalyzed Preparation of Weinreb Amides from Boronic Acids and N-Methyl-N-methoxycarbamoyl Chloride

A simple protocol for the synthesis of Weinreb benzamides and α,β-unsaturated Weinreb amides through a palladium-catalyzed cross-coupling reaction between organoboronic acids and N-methoxy-N-methylcarbamoyl chloride has been developed. The method is also applicable to the use of potassium organotrifluoroborates.
Air quality diffusion model: application to New York city

An experimental multisource air pollution diffusion model based on the Gaussian plume formulation is described. The model incorporates point and area sources, time and space dependence of source strengths, and time and space dependence of meteorological variables. Numerical simulation of the SO2 concentration distribution for New York City on January 11, 197l, agrees favorably with experimental measurements.
Predictors of self-management for chronic low back pain

Abstract Aims (a) Identify variables that predict self-management (SM) of chronic low back pain (CLBP), and (b) evaluate differences in these variables between participants in specialty pain centers (SPCs) and primary care clinics (PCCs). Background Chronic low back pain is highly prevalent in various healthcare settings. Self-management strategies are recommended in pain care guidelines to help address CLBP. However, the evidence of SM effectiveness in CLBP remains unclear. Self-management may be effective for only certain patients. Hence, identifying the predictors to SM of CLBP is essential to help recognize the best responders to SM programs. Method Secondary analysis was conducted on data collected from two CLBP primary research studies in SPCs ( N =110) and PCCs ( N =120). General linear modeling was utilized for the combined sample of 230 participants and for each practice setting. Results Overall, in SPCs and PCCs combined, five variables were found to be predictors of SM: age, SM support, education, overall health, and helpfulness of pain management. In SPCs, SM support, support received from other than healthcare providers, religion or spirituality, and overall health were identified as significant predictors to SM. In PCCs, both SM support and overall health were also significant predictors. In addition, those with higher income scored better in SM. Conclusions Findings provide essential information to healthcare providers in intervening appropriately toward engaging CLBP patients in SM. Other strategies need to be identified for those who do not respond effectively to SM strategies.
Paying For Joint Costs in Health Care

The paper analyzes a regulatory game between a public and a private payer to finance hospital joint costs (mainly capital and technology expenses). The public payer (inspired by the federal Medicare program) may both directly reimburse for joint costs (“pass-through” payments) and add a margin over variable costs paid per discharge, while the private payer can only use a margin policy. The hospital chooses joint costs in response to payers' overall payment incentives. Without pass-through payments, under provision of joint costs results front free-riding behavior of payers and the first-mover advantage of the public payer. Using pass-through policy in its self-interest, the public payer actually may moderate the under provision of joint costs; under some conditions, the equilibrium allocation may be socially efficient. Our results bear directly on directly Medicare policy, which is phasing out pass-through payments.
Prolonging the life of software

Presented here are methods for successfully controlling software maintenance activity so that present systems will be more useful and less expensive to support. While it is based on experience at Los Alamos National Laboratory, it is not based on solutions developed and implemented there. Los Alamos is presently struggling with the problems identified in this paper and is impacted by them to the same extent as the rest of industry. An idea has emerged from this struggle: The deterioration of production software is basically a quality control problem the rate of which can and should be minimized. Many data processing shops currently have two options concerning old (over five years), marginally useful systems; pay the high cost of supporting them or undertake a rewrite. If the principles presented in this paper are applied, a third option may become available; prolonging the useful life of software by making it more cost-effective to support.
Defects Can Increase the Melting Temperature of DNA−Nanoparticle Assemblies

DNA-gold nanoparticle assemblies have shown promise as an alternative technology to DNA microarrays for DNA detection and RNA profiling. Understanding the effect of DNA sequences on the melting temperature of the system is central to developing reliable detection technology. We studied the effects of DNA base-pairing defects, such as mismatches and deletions, on the melting temperature of DNA-nanoparticle assemblies. We found that, contrary to the general assumption that defects lower the melting temperature of DNA, some defects increase the melting temperature of DNA-linked nanoparticle assemblies. The effects of mismatches and deletions were found to depend on the specific base pair, the sequence, and the location of the defects. Our results demonstrate that the surface-bound DNA exhibit hybridization behavior different from that of free DNA. Such findings indicate that a detailed understanding of DNA-nanoparticle assembly phase behavior is required for quantitative interpretation of DNA-nanoparticle aggregation.
Imaging of prostate cancer: a platform for 3D co-registration of in-vivo MRI ex-vivo MRI and pathology

Objectives: Multi-parametric MRI is emerging as a promising method for prostate cancer diagnosis. prognosis and treatment planning. However, the localization of in-vivo detected lesions and pathologic sites of cancer remains a significant challenge. To overcome this limitation we have developed and tested a system for co-registration of in-vivo MRI, ex-vivo MRI and histology. Materials and Methods: Three men diagnosed with localized prostate cancer (ages 54-72, PSA levels 5.1-7.7 ng/ml) were prospectively enrolled in this study. All patients underwent 3T multi-parametric MRI that included T2W, DCEMRI, and DWI prior to robotic-assisted prostatectomy. Ex-vivo multi-parametric MRI was performed on fresh prostate specimen. Excised prostates were then sliced at regular intervals and photographed both before and after fixation. Slices were perpendicular to the main axis of the posterior capsule, i.e., along the direction of the rectal wall. Guided by the location of the urethra, 2D digital images were assembled into 3D models. Cancer foci, extra-capsular extensions and zonal margins were delineated by the pathologist and included in 3D histology data. A locally-developed software was applied to register in-vivo, ex-vivo and histology using an over-determined set of anatomical landmarks placed in anterior fibro-muscular stroma, central. transition and peripheral zones. The mean root square distance across corresponding control points was used to assess co-registration error. Results: Two specimens were pT3a and one pT2b (negative margin) at pathology. The software successfully fused invivo MRI. ex-vivo MRI fresh specimen and histology using appropriate (rigid and affine) transformation models with mean square error of 1.59 mm. Coregistration accuracy was confirmed by multi-modality viewing using operator-guided variable transparency. Conclusion: The method enables successful co-registration of pre-operative MRI, ex-vivo MRI and pathology and it provides initial evidence of feasibility of MRI-guided surgical planning.
Changing patterns of childhood aphasia

Acquired aphasia in children has been generally characterized as nonfluent, transient, and frequently due to right hemisphere lesions. We studied 65 children with unilateral hemispheric brain lesions occurring after speech acquisition any time from the second through the fourteenth year. Of 34 patients with a left hemisphere lesion, 25 had an initial aphasic speech disturbance, while of 31 patients with a right hemisphere lesion, only 4 (including 2 left-handers) showed any initial aphasia. All those who became aphasic before the age of 8 years eventually regained speech, but recovery time required ranged from less than a month to more than two years. One 5-year-old boy who recovered had initial jargon aphasia. Our review of the literature indicated that the conflict between our results and the traditional claim of frequent aphasia with right hemisphere lesions only apparent; the great majority of crossed aphasias are concentrated in reports written before antibiotics were used, and many cases were assoicated with systemic bacterial infections.
Polar-coordinate laser writer for binary optics fabrication

A Laser Writer system for recording centro-symmetric patterns in photoresist has been developed as an alternative method for binary optics mask and component fabrica.- tion.This system is capable of generating binary amplitude patterns with linewidths below 1 tm and with a positional accuracy of less than 0.ljim on up to 3 in. diameter planar substrates. The measured wavefront error and diffraction efficiency of a directwrite two-phase-level F/10 lens confirm that high quality components can be fabricated quickly, easily, and at low cost.
The filter-placement problem and its application to minimizing information multiplicity

In many information networks, data items -- such as updates in social networks, news flowing through interconnected RSS feeds and blogs, measurements in sensor networks, route updates in ad-hoc networks -- propagate in an uncoordinated manner: nodes often relay information they receive to neighbors, independent of whether or not these neighbors received the same information from other sources. This uncoordinated data dissemination may result in significant, yet unnecessary communication and processing overheads, ultimately reducing the utility of information networks. To alleviate the negative impacts of this information multiplicity phenomenon, we propose that a subset of nodes (selected at key positions in the network) carry out additional information filtering functionality. Thus, nodes are responsible for the removal (or significant reduction) of the redundant data items relayed through them. We refer to such nodes as filters. We formally define the Filter Placement problem as a combinatorial optimization problem, and study its computational complexity for different types of graphs. We also present polynomial-time approximation algorithms and scalable heuristics for the problem. Our experimental results, which we obtained through extensive simulations on synthetic and real-world information flow networks, suggest that in many settings a relatively small number of filters are fairly effective in removing a large fraction of redundant information.
Microstructural Changes and Volatilization of Rh and Rh/Ce on SiO2 and Al2O3 in NO + CO

Dramatic changes in the microstructures of Rh and Rh/Ce supported on SiO[sub 2] and Al[sub 2]O[sub 3] occur after treatments in NO + CO at temperatures as low as 300[degrees]C. Silica-supported Rh was nearly completely volatilized by treatment in NO + CO at 300[degrees]C, but the addition of Ce was found to retard this effect. Examination of the effects of the individual gases showed that NO alone disperses Rh over the SiO[sub 2] and CO alone volatilizes the dispersed Rh formed by treatment in NO. However, heating in CO alone had no effect on undispersed Rh. The activity of Rh on porous SiO[sub 2] for NO + CO at 200[degrees]C decreased by a factor of five after heating overnight at 300[degrees]C due to loss of Rh. On alumina, heating in NO + CO had much less effect and only a few smaller particles disappeared even after extensive treatment at 400[degrees]C. Heating in NO alone, however, did disperse the Rh into small ([approximately]20 [Angstrom]) particles on the Al[sub 2]O[sub 3]. Similar changes were observed for Rh/Ce. The NO + CO activity on alumina actually increased slightly by heating at 300[degrees]C for extended time. XPS indicates the presence of small amounts ofmore » oxidized Rh on both supports after heating in NO + CO, but cannot identify whether this is the dispersed Rh or the oxidized surface of Rh particles. The authors speculate that dispersion may be through the formation of a mobile nitrosyl complex and volatilization by formation of volatile carbonyls. 19 refs., 15 figs.« less
Fundamentals of corrosion fouling

This paper reviews the fouling of heat transfer surfaces caused by corrosion as a consequence of their exposure to flowing oxygenated water. The fundamental mechanisms of oxygen transport, deposit growth, and deposit removal are considered. A model for predicting the formation of a corrosion fouling deposit is derived and the utility of dimensionless variables deduced from the model is demonstrated. The interaction of corrosion fouling and other categories of fouling is discussed. Recommendations are made for future research in this area.
Organic chemistry on solid surfaces

Abstract Chemistry on solid surfaces is central to many areas of practical interest such as heterogeneous catalysis, tribology, electrochemistry, and materials processing. With the development of many surface-sensitive analytical techniques in the past decades, great advances have been possible in our understanding of such surface chemistry at the molecular level. Earlier studies with model systems, single crystals in particular, have provided rich information about the adsorption and reaction kinetics of simple inorganic molecules. More recently, the same approach has been expanded to the study of the surface chemistry of relatively complex organic molecules, in large measure in connection with the selective synthesis of fine chemicals and pharmaceuticals. In this report, the chemical reactions of organic molecules and fragments on solid surfaces, mainly on single crystals of metals but also on crystals of metal oxides, carbides, nitrides, phosphides, sulfides and semiconductors as well as on more complex models such as bimetallics, alloys, and supported particles, are reviewed. A scheme borrowed from the organometallic and organic chemistry literature is followed in which key examples of representative reactions are cited first, and general reactivity trends in terms of both the reactants and the nature of the surface are then identified to highlight important mechanistic details. An attempt has been made to emphasize recent advances, but key earlier examples are cited as needed. Finally, correlations between surface and organometallic and organic chemistry, the relevance of surface reactions to applied catalysis and materials functionalization, and some promising future directions in this area are briefly discussed.
The Witt Ring of a Smooth Projective Curve Over a Finite Field

In this paper, we calculate the Witt ring W(C) of a smooth geometrically connected projective curve C over a finite field with characteristic other than 2. We view W(C) as a subring of W(k(C)) where k(C) is the function field of C. The calculation is then completed using classical results for bilinear spaces over fields.
Activity of ordered and disordered Pt-Co alloy phases for the electroreduction of oxygen in catalysts with multiple coexisting phases

Abstract This study investigates the relative electrochemical activity of ordered and disordered Pt-Co alloy phases coexisting in multi-phase catalyst materials. Of particular interest is the effect of the relative distribution between ordered and disordered Pt-Co alloy phases on the observed electrocatalytic activity for the oxygen reduction reaction (ORR). Three Pt-Co catalysts with identical overall composition, Pt 50 Co 50 , but with distinct distributions between two disordered face centered cubic (fcc) Pt-Co alloy phases and one ordered face centered tetragonal (fct) alloy phase are considered. Comparing the structure of the catalysts with their electrocatalytic activity for ORR suggests that the Co-rich (60–80 at% Co) disordered phase is linked to the observed 3× activity enhancement compared to a pure Pt catalyst. If the ordered fct phase outweighs the Co-rich disordered phase the activity drops drastically. It is concluded that Co-rich disordered phases are the preferred Pt-Co alloy phases with respect to catalyst activity.
Synthesis of the isoxazolo[4,3,2-de]phenanthridinone moiety of the parnafungins.

A practical route to the labile tetracyclic isoxazolo[4,3,2-de]phenanthridinone moiety of the antifungal parnafungins has been developed. Zinc reduction of a methyl 2′-hydroxymethyl-2-nitro-3-biphe...
Atomic-beam density determination from laser-induced fluorescence interval distributions

A resonance fluorescence method is demonstrated whereby the density of an atomic beam can be determined reliably. This determination is based on the distribution of time intervals between detected photons, and is made without independent knowledge of excitation cross sections, laser beam intensity, or photon counting efficiency.
Volatile barium β-diketonates for use as MOCVD precursors

Metal-organic chemical vapor deposition (MOCVD) techniques have been used to deposit thin superconducting films of YBa2Cu3O7-x. A limitation of the technique lies in the volatility of the barium(II) precursors. A review of attempts to enhance volatility through substitution of fluorinated chelating agents and studies to limit oligomerization of the barium chelates are reviewed. Within the past five years, substantial progress has been made in synthesizing more volatile barium complexes, and the most volatile barium compound yet reported is a monomeric chelate in which five hexafluoroacetylacetonato ligands are bonded to barium(II).
Probing supersymmetry with third-generation cascade decays

The chiral structure of supersymmetric particle couplings involving third generation Standard Model fermions depends on left-right squark and slepton mixings as well as gaugino-higgsino mixings. The shapes and intercorrelations of invariant mass distributions of a first or second generation lepton with bottoms and taus arising from adjacent branches of SUSY cascade decays are shown to be a sensitive probe of this chiral structure. All possible cascade decays that can give rise to such correlations within the MSSM are considered. For bottom-lepton correlations the distinctive structure of the invariant mass distributions distinguishes between decays originating from stop or sbottom squarks through either an intermediate chargino or neutralino. For decay through a chargino the spins of the stop and chargino are established by the form of the distribution. When the bottom charge is signed through soft muon tagging, the structure of the same-sign and opposite-sign invariant mass distributions depends on a set function of left-right and gaugino-higgsino mixings, as well as establishes the spins of all the superpartners in the sequential two-body cascade decay. Tau-lepton and tau-tau invariant mass distributions arising from MSSM cascade decays are likewise systematically considered with particular attention to their dependence on tau polarization. All possible tau-lepton and tau-tau distributions are plotted using a semi-analytic model for hadronic one-prong taus. Algorithms for fitting tau-tau and tau-lepton distributions to data are suggested.
Selective Deprotection of Silyl-Protected Phenols Using Solid NaOH and a Phase Transfer Catalyst

Aryl silyl ethers can be deprotected to yield phenols in good to excellent yields using a biphasic system of 10 equivalents of NaOH and catalytic Bu4NHSO4 in 1,4- dioxane. Alkyl silyl ethers prepared using a variety of silyl protecting groups survive under these conditions, allowing selective deprotection of silyl-protected phenols in the presence of silyl-protected alcohols. © 1999 Elsevier Science Ltd. All rights reserved. Protection/deprotection protocols using silyl protecting groups are among the most widely used methods for temporarily masking alcohols. 1,2 As synthetic targets have become increasingly complex, methods to selectively remove one such silyl group in the presence of another have been developed. 3 Although discrimination between two silyl ethers derived from alcohols is common, relatively few techniques have been developed to deprotect aryl silyl ethers in the presence of alkyl silyl ethers. 3 Although camphorsulfonic acid / methanol 4 and aqueous DMSO 5 have been used to cleave aryl TBS ethers in the presence of alkyl TBS ethers, a survey of the methods reported to effect selective desilylation of aryl silyl ethers reveals basic conditions to be the norm. 3 Davies has demonstrated that, while the desilylation of the TBS ether of p-cresol in 5% NaOH / 95% MeOH has a half-life of 3.5 minutes, the TBS ether of n-hexanol is stable over 24 hours. 6 Among the systematically-studied basic reagents reported to effect selective removal of silyl groups from phenols are: TBAF, 7,8 KF/ 18- crown-6, 8 KF / alumina, 9 K2CO3 / Kryptofix 222,10 K2CO3 / aqueous EtOH 11 and Dowex I-X8 (OH- form). 12 Other methods employing TBAF have been reported as parts of total syntheses. 13-16 Some of these methods require elevated reaction temperatures, 5,10,11,17 lengthy reaction times 5,8 and aqueous workup. We have developed a system that allows selective deprotection of aryl silyl ethers in the presence of alkyl silyl ethers at mild temperatures and with relatively short reaction times and wish to report our findings. Phenols have been reported to undergo selective acylation in the presence of alcohols using powdered NaOH and Bu4NHSO4 in a number of organic solvents. 18 We examined this system as a possible means to deliver OH- ions 19 to silyl-protected phenols in a non-aqueous medium, thereby effecting desilylation. Initial studies (Table 1) on bis-silyl ether 1 showed 10
Convenient synthesis of 9-alkyl and 9-arylacridines from [2 - (trimethylsilyl) ethoxy] methyl (sem) protected acridone

Abstract The low yielding addition of organolithium reagents to acridone becomes a convenient high yielding route to 9-alkyl and 9-arylacridines when SEM-acridone is used.
Aminodiols via Stereocontrolled Oxidation of Methyleneaziridines

A highly diastereoselective Ru-catalyzed oxidation/reduction sequence of bicyclic methyleneaziridines provides a facile route to complex 1-amino-2,3-diol motifs. The relative anti stereochemistry between the amine and the vicinal alcohol are proposed to result from 1,3-bischelation in the transition state by the C1 and C3 heteroatoms.
Mechanism of the rearrangement of 2-(vinyloxy)alkyl to 4-ketobutyl radicals

Abstract The rearrangement of 2-(vinyloxy)alkyl to 4-ketobutyl radicals has been demonstrated to proceed by a two step mechanism involving initial 5-endo-trigonal cyclization to give a tetrahydrofuranyl radical which then fragments to the final radical. Fragmentation of the tetrahydrofuranyl radicals is demonstrated by their generation from the corresponding 2-(ethylthio)-tetrahydrofurans with stannanes and AIBN. The rearrangement reaction is completely blocked when the intermediate tetrahdrofuranyl radical is set up to undergo a 5-hexenyl rearrangement.
SUZAKU OBSERVATIONS OF THE PROTOTYPE WIND-BLOWN BUBBLE NGC 6888

We present an analysis of the Suzaku observations of the prototype wind-blown bubble NGC 6888 which is based both on use of standard spectral models and on a direct comparison of theoretical models with observations. The X-ray spectra of NGC 6888 are soft and most of the X-rays are in the 0.3-1.5 keV energy range. But, hard X-rays (1.5-4.0 keV) are also detected (~10% of the observed flux). The corresponding spectral fits require a relatively cool plasma with kT ≤ 0.5 keV, but a much hotter plasma with temperature kT ≥ 2.0 keV is needed to match the observed hard X-ray emission. We find no appreciable temperature variations within the hot bubble in NGC 6888. The derived abundances (N, O, Ne) are consistent with those of the optical nebula. This indicates a common origin of the X-ray emitting gas and the outer cold shell: most of the X-ray plasma (having non-uniform spatial distribution: clumps) has flown into the hot bubble from the optical nebula. If the electron thermal conduction is efficient, this can naturally explain the relatively low plasma temperature of most of the X-ray emitting plasma. Alternatively, the hot bubble in NGC 6888 will be adiabatic and the cold clumps are heated up to X-ray temperatures likely by energy exchange between the heavy particles (hot ions diffusing into the cold clumps).
Densitometric Analysis Of Blood Flow Of The Optic Nerve Head In Glaucoma

In glaucoma the increased level of pressure within the eye results in atrophy of the optic nerve with loss in visual function. Impairment of the blood supply to the optic nerve by the increased pressure appears to be primarily responsible for the atrophy. Sequential photographs of the optic nerve head after an intravenous injection of fluorescein dye provide a detailed topography of its vascular system as a function of time. Densitometric techniques can be utilized as a means of objective analysis and measurement to separate normal vascular patterns from those of the glaucomatous patient. Techniques for the analysis of peak times, circulation times, intensity ratios and flow rates are described in normal and glaucomatous optic nerve heads.
Near-group categories

We consider the possibility of semisimple tensor categories whose fusion rule includes exactly one noninvertible simple object. Con- ditions are given for the existence or nonexistence of coherent associative structures for such fusion rules, and an explicit construction of matrix so- lutions to the pentagon equations in the cases where we establish existence. Many of these also support (braided) commutative and tortile structures and we indicate when this is possible. Small examples are presented in detail. AMS Classication 18D10
Revisions In Need Of Revising: What Went Wrong In The Iraq War

Though critics have made a number of telling points against the Bush admin-istration's conduct of the Iraq war, the most serious problems facing Iraq and its American occupiers – criminal anarchy and lawlessness, a raging insurgency and a society divided into rival and antagonistic groups – were virtually inevitable consequences that flowed from the act of war itself. Military and civilian planners were culpable in failing to plan for certain tasks, but the most serious problems had no good solution. Even so, there are lessons to be learned. These include the danger that the imperatives of ‘force protection’ may sacrifice the broader political mission of US forces and the need for scepticism over the capacity of outsiders to develop the skill and expertise required to reconstruct decapitated states.
Optimization of solid supports for combinatorial chemical synthesis.

Until recently, resins were used primarily for peptide and oligonucleotide synthesis. Recent advances in combinatorial chemistry have fostered increased acceptance of resins as supports for the synthesis of small molecule libraries. The methodology for selecting a resin bead that is ideal for the solid phase synthesis of small molecules is described in this review. The process of manufacturing a typical resin, the UniSphere®-200, is also explained. Furthermore, a new approach is proposed for the solid phase synthesis of analogs which are traditionally done in solution phase. This new procedure involves the use of building blocks attached to an activated resin. These building blocks are displaced by a functional group on the scaffold around which the analogs are built. Use of an excess of resin-linked building blocks drives the reaction to completion. Additionally, a newly developed, grafted surface solid support, is described. This support, the MicroTube,® can be used for the synthesis of large numbers of discrete molecules by a patented directed sorting method. © John Wiley & Sons, Inc. Med Res Rev, 19, No. 5, 451–462, 1999.
Automated map reading and analysis by computer

A great deal of attention is presently being given to the design of computer programs to recognize and describe two-dimensional pictorial symbology. This symbology may arise from natural sources such as scenery or from more conventionalized sources such as text or mathematical notation. The standardized graphics used in specification of topographic maps also form a conventionalized, two-dimensional class of symbology.
Screening for congenital hypothyroidism

Population screening for congenital hypothyroidism was introduced in the early 1970s and now is routine in most of the industrialized world. Such screening has facilitated the characterization and refined the nosology of a spectrum of thyroid disorders in the neonatal period. Moreover, newborn screening has fulfilled the promise of minimizing the mental retardation otherwise common in infants with congenital hypothyroidism. Careful management of detected infants is essential, and physicians must remember that some infants, perhaps 10% of the total, may escape detection in screening programs. A high index of suspicion is necessary to assure early clinical detection and treatment of these infants.
Complete Characterization and Synthesis of the Response Function of Elastodynamic Networks

The response function of a network of springs and masses, an elastodynamic network, is the matrix valued function W(ω), depending on the frequency ω, mapping the displacements of some accessible or terminal nodes to the net forces at the terminals. We give necessary and sufficient conditions for a given function W(ω) to be the response function of an elastodynamic network, assuming there is no damping. In particular we construct an elastodynamic network that can mimic a suitable response in the frequency or time domain. Our characterization is valid for networks in three dimensions and also for planar networks, which are networks where all the elements, displacements and forces are in a plane. The network we design can fit within an arbitrarily small neighborhood of the convex hull of the terminal nodes, provided the springs and masses occupy an arbitrarily small volume. Additionally, we prove stability of the network response to small changes in the spring constants and/or addition of springs with small spring constants.
Failure analysis of contact probe pins for SnPb and Sn applications

A study has been conducted to investigate the failure mechanism of pogo pin-type probe contacts. Probe pins are used for electrical test of microelectronic components in manufacturing. A false rejection of parts due to high probe contact resistance results in a penalty in cost and yield. The probe pin contact bears distinctive characteristics of failure compared to the conventional contact systems such as mechanical switches and interconnects. Moreover, the transition to Pb-free component leads demands understanding of different probe failure mechanisms between a SnPb and Sn surface. The objective of this study is to understand this unique failure mechanism and the effect of lead coating metals on probe pin life. This has not been clearly elucidated to date in spite of its significant impact on yield and cost of electronic package manufacturing. A simulated probe tester with 3-axes actuation capability was devised to mimic the actual test process. The force required to penetrate the surface oxide layer and develop electrical contact was measured. Contact resistance history revealed that probe pins mating to Sn surfaces failed earlier than pins used on SnPb surfaces. Through periodic inspection of probe pins using microprobe/EDS as a function of probe actuations, the general root cause of probe pin failure was found to be probe pin tip wear out associated with the Sn oxide growth on its surface. The matte Sn surface wears the probe pin more than SnPb due to the rough and abrasive nature of the matte Sn surface.
Continuous-flow microfluidic blood cell sorting for unprocessed whole blood using surface-micromachined microfiltration membranes

White blood cells (WBCs) constitute about 0.1% of the blood cells, yet they play a critical role in innate and adaptive immune responses against pathogenic infections, allergic conditions, and malignancies and thus contain rich information about the immune status of the body. Rapid isolation of WBCs directly from whole blood is a prerequisite for any integrated immunoassay platform designed for examining WBC phenotypes and functions; however, such functionality is still challenging for blood-on-a-chip systems, as existing microfluidic cell sorting techniques are inadequate for efficiently processing unprocessed whole blood on chip with concurrent high throughput and cell purity. Herein we report a microfluidic chip for continuous-flow isolation and sorting of WBCs from whole blood with high throughput and separation efficiency. The microfluidic cell sorting chip leveraged the crossflow filtration scheme in conjunction with a surface-micromachined poly(dimethylsiloxane) (PDMS) microfiltration membrane (PMM) with high porosity. With a sample throughput of 1 mL h−1, the microfluidic cell sorting chip could recover 27.4 ± 4.9% WBCs with a purity of 93.5 ± 0.5%. By virtue of its separation efficiency, ease of sample recovery, and high throughput enabled by its continuous-flow operation, the microfluidic cell sorting chip holds promise as an upstream component for blood sample preparation and analysis in integrated blood-on-a-chip systems.