cssi/SciSciGPT-SciSciNet huggingface dataset:
Ugi/aldol sequence: expeditious entry to several families of densely substituted nitrogen heterocycles.

All it takes is the Aldol Nitrogen containing heterocycles have been assembled by means of unprecedented domino processes, designed to take advantage of diversity assembly via strategically decorated Ugi products. The aldol reaction is the second common denominator which enables sequences of up to 5 steps in one pot producing unique molecular architecture in rapid fashion.
Multi-paradigm multi-scale simulations for fuel cell catalysts and membranes

Dramatically improving the performance of fuel cell systems with their complex heterogeneous structures involving electrocatalysts, proton conducting membrane, reactant, and interfaces between them requires understanding the fundamental chemical, electrochemical, and physical phenomena at the heart of these complex materials and relating these fundamentals to the properties and performance of the membrane–electrode assembly. Our goal is to develop a predictive model that can be used to estimate the changes in performance upon changes in the design and which can be used to monitor performance of working fuel cells. Our strategy is to start with first principles quantum mechanics (QM) and to develop overlapping simulation methodologies in which QM is used to train a reactive force field that can be applied for large-scale (millions of atom) molecular dynamics simulations while retaining the accuracy of QM. The results of molecular dynamics are used to extract a coarse grain or mesoscale description useful i...
Shielding effect of on-chip interconnect inductance

Interconnect inductance introduces a shielding effect which decreases the effective capacitance seen by the driver of a circuit, reducing the gate delay. A model of the effective capacitance of an RLC load driven by a CMOS inverter is presented. The interconnect inductance decreases the gate delay and increases the time required for the signal to propagate across an interconnect, reducing the overall delay to drive an RLC load. Ignoring the line inductance overestimates the circuit delay, inefficiently oversizing the circuit driver. Considering line inductance in the design process saves gate area, reducing dynamic power dissipation. Average reductions in power of 17% and area of 29% are achieved for example circuits. An accurate model for a CMOS inverter and an RLC load is used to characterize the propagation delay. The accuracy of the delay model is within an average error of less than 9% as compared to SPICE.
Molecular organogels. Soft matter comprised of low-molecular-mass organic gelators and organic liquids.

This Account presents recent advances in understanding how and why dilute solutions/sols of low-molecular-mass organic gelators (LMOGs) undergo microscopic phase separation to form self-assembled fibrillar networks in molecular organogels. Concepts are illustrated structurally at the subnanometer (molecular) to several millimeter (bulk) length scales and dynamically over time scales that follow the assembly of supersaturated solutions/sols into gel phases. Examples include both structurally complicated (ALS molecules with aromatic, linking, and steroidal groups) and simple (n-alkanes or n-alkanes along whose chains a hetero-group has been inserted) LMOGs in a wide range of organic liquids.
Local Dividend Clienteles

We exploit demographic variation to identify the effect of dividend demand on corpo? rate payout policy Retail investors tend to hold local stocks and older investors prefer dividend-paying stocks. Together, these tendencies generate geographically varying demand for dividends. Firms headquartered in areas in which seniors constitute a large fraction of the population are more likely to pay dividends, initiate dividends, and have higher dividend yields. We also provide indirect evidence as to why man? agers may respond to the demand for dividends from local seniors. Overall, these results are consistent with the notion that the investor base affects corporate policy choices. This paper examines the role of investor demand in shaping corporate payout policy. Miller and Modigliani (1961) suggest that matching takes place between investor clienteles who demand dividends and those firms that find it less costly to pay them, that is, companies set payout policy and investors sort based on their preferences for dividends. On the other hand, firms may actively respond to the preferences of their current shareholders. The empirical patterns will be the same regardless of the direction of the underlying causal relation (payout policies match investor preferences), but the implications for understanding
Automated Derivation of Primitives for Movement Classification

We describe a new method for representing human movement compactly, in terms of a linear super-imposition of simpler movements termed i>primitives. This method is a part of a larger research project aimed at modeling motor control and imitation using the notion of perceptuo-motor primitives, a basis set of coupled perceptual and motor routines. In our model, the perceptual system is biased by the set of motor behaviors the agent can execute. Thus, an agent can automatically classify observed movements into its executable repertoire. In this paper, we describe a method for automatically deriving a set of primitives directly from human movement data. We used movement data gathered from a psychophysical experiment on human imitation to derive the primitives. The data were first filtered, then segmented, and principal component analysis was applied to the segments. The eigenvectors corresponding to a few of the highest eigenvalues provide us with a basis set of primitives. These are used, through superposition and sequencing, to reconstruct the training movements as well as novel ones. The validation of the method was performed on a humanoid simulation with physical dynamics. The effectiveness of the motion reconstruction was measured through an error metric. We also explored and evaluated a technique of clustering in the space of primitives for generating controllers for executing frequently used movements.
Whence Philosophy of Biology

A consensus exists among contemporary philosophers of biology about the history of their field. According to the received view, mainstream philosophy of science in the 1930s, 40s, and 50s focused on physics and general epistemology, neglecting analyses of the ‘special sciences’, including biology. The subdiscipline of philosophy of biology emerged (and could only have emerged) after the decline of logical positivism in the 1960s and 70s. In this paper, I present bibliometric data from four major philosophy of science journals (Erkenntnis, Philosophy of Science, Synthese, and the British Journal for the Philosophy of Science), covering 1930-1959, which challenge this view.
Radical Reaction of Sodium Hypophosphite with Terminal Alkynes: Synthesis of 1,1-Bis-H-phosphinates

The room-temperature radical addition of sodium hypophosphite to terminal alkynes produces the previously unknown 1-alkyl-1,1-bis-H-phosphinates in moderate yield. The reaction is initiated by R3B and air and proceeds under mild conditions in an open container. The bissodium salts precipitate spontaneously from the reaction mixtures, thus providing a simple purification procedure and the opportunity for multigram synthesis. The 1,1-bis-H-phosphinate products are novel precursors of the biologically important 1,1-bisphosphonates.
A Historical Perspective on Parental Alienation Syndrome and Parental Alienation

Claims of parental alienation syndrome (PAS) and parental alienation (PA) have come to dominate custody litigation, especially where abuse is alleged. Although much psychological and legal literature has critiqued PAS, and leading researchers as well as most professional institutions have renounced the syndrome concept, alienation as a parental behavior or child’s condition continues to be extensively investigated and credited in research and forensic contexts. This article reviews the history of PAS, both as posited by its inventor, Richard Gardner, and as used and applied in courts, suggesting that it not only lacks empirical basis or objective merit, but that it derives from its author’s troubling beliefs about adult and child sexual interaction. It then examines the more recent explorations of non-syndrome ‘‘alienation’’ as proffered by Janet Johnston and others, noting both its more balanced and grounded nature and its more modest remedial implications. However, the article concludes that PA is too closely tied to PAS to be an adequate improvement. It, too, is used crudely in courts to defeat abuse allegations, it continues to rely on speculations about mothers’ purported unconscious desires and their effects on children, and, more subtly than PAS, it minimizes abuse and its effects on mothers and children. At root, although even PA researchers have found it to be a real issue in only a small minority of contested custody cases, courts’ and evaluators’ extensive focus on it in response to mothers’ abuse allegations continues to privilege false or exaggerated alienation concerns over valid concerns about abuse.
Policy Implications of the Trade and Wages Debate

This paper examines the choice of policies to redistribute income in response to an increase in inequality caused by a rise in the differential wage paid to skilled labor compared with unskilled labor. The main issue is whether the appropriate policy response depends on whether the cause of the increased skill differential is ‘trade’—increased competition with low-skilled workers abroad—or technological change. The analysis is conducted within the context of a two-sector Heckscher–Ohlin trade model augmented to allow endogenous determination of the level of skill.
Information Technology, Productivity, and Asset Ownership: Evidence from Taxicab Fleets

We develop a simple model that links the adoption of a productivity-enhancing technology to increased vertical integration and a less skilled workforce. We test the model’s key prediction using novel microdata on vehicle ownership patterns from the Economic Census during a period when computerized dispatching systems were first adopted by taxicab firms. Controlling for time-invariant firm-specific effects, firms increase the proportion of taxicabs under fleet ownership by 12% when they adopt new computerized dispatching systems. An instrumental variables analysis suggests that the link between dispatching technology and vertical integration is causal. These findings suggest that increasing a firm’s productivity can lead to increased vertical integration, even in the absence of asset specificity.
Noble metal decoration of single crystal platinum surfaces to create well-defined bimetallic electrocatalysts

Electrocatalytic studies on bimetallic single crystal electrodes present a unique opportunity to explore the reactivity of complex surfaces with known structure and composition. Such electrochemical studies, together with measurements in ultra-high vacuum, provide the theoretical and experimental basis for rational design of more active electrocatalysts. Pure platinum, though the most active single-component electrocatalyst for many reactions, is still not active enough for some applications, particularly in fuel cell technology, and cannot be considered as a true catalyst for most electrocatalytic processes. Therefore, a concerted effort has been made in the last 40 years to enhance the electrocatalytic activity of Pt via modification by a second metal. Most early work used polycrystalline alloys, but in recent years, many workers have begun modifying (decorating) Pt single crystals by deposition of a second noble metal, which is usually ruthenium, palladium, rhodium, osmium, or silver. A critical review of electrocatalysis on such well-defined bimetallic surfaces is offered, and a brief analysis of the inverted approach, in which single crystal noble metal surfaces are modified by Pt deposition, is also presented.
Earw(h)ig: I can’t hear you because your ideas are old

This paper provides a critical challenge to the Whig view of economic ideas, which holds that good ideas from the past are embodied in the common scientific wisdom. In contrast to this position, we contend that the market for ideas, while no doubt competitive in terms of scientific rivalry, is not free of distortions in the incentives and signals that guide economic scientists. As a result, ideas that are flawed can come to dominate the profession, while useful ideas are left on the proverbial sidewalk of intellectual affairs. The smooth evolution of economic thought from falsehood to truth that underlies the Whig perspective is complicated by both historical circumstances and the intimate relationship between economics and politics that follows from the attraction of public policy for those who enter the discipline.
Cool horizons for entangled black holes

General relativity contains solutions in which two distant black holes are connected through the interior via a wormhole, or Einstein-Rosen bridge. These solutions can be interpreted as maximally entangled states of two black holes that form a complex EPR pair. We suggest that similar bridges might be present for more general entangled states. In the case of entangled black holes one can formulate versions of the AMPS(S) paradoxes and resolve them. This suggests possible resolutions of the firewall paradoxes for more general situations.
Graph expansion and communication costs of fast matrix multiplication

The communication cost of algorithms (also known as I/O-complexity) is shown to be closely related to the expansion properties of the corresponding computation graphs. We demonstrate this on Strassen's and other fast matrix multiplication algorithms, and obtain the first lower bounds on their communication costs. In the sequential case, where the processor has a fast memory of size M, too small to store three n-by-n matrices, the lower bound on the number of words moved between fast and slow memory is, for a large class of matrix multiplication algorithms, Ω( (n/√M)ω0 ·M), where ω0 is the exponent in the arithmetic count (e.g., ω0 = lg 7 for Strassen, and ω0 = 3 for conventional matrix multiplication). With p parallel processors, each with fast memory of size M, the lower bound is asymptotically lower by a factor of p. These bounds are attainable both for sequential and for parallel algorithms and hence optimal.
Chromosomal Receptor for a Vitamin D Metabolite

Evidence has been presented for the existence of an acidic protein(s) or protein portion of a more complex molecule which has a high affinity for binding noncovalently a biologically active metabolite of vitamin D. This molecule could be solubilized from the residual chromatin via treatment with either 0.3 M KCl or high pH and has been purified 167-fold over the crude mucosa homogenate. Characterization of the still crude receptor fraction showed that it contains significant amounts of RNA and that it may exist in multiple forms, i.e., a 50,000-70,000 and a >200,000 molecular weight species. The binding capacity of the receptor fraction for the metabolite is saturated after administration of a physiological dose of the parent vitamin D.
LDPC-Coded MIMO Optical Communication Over the Atmospheric Turbulence Channel

In this paper, coded multiple-input-multiple-output (MIMO) communication schemes for data transmission over the optical atmospheric turbulence channels are studied. Two strategies are proposed and compared. The first is based on repetition coding, and the second on space-time (ST) coding. Both approaches employ low-density parity-check (LDPC) codes. The LDPC codes are designed using the concept of pairwise balanced design (PBD), balanced incomplete block design (BIBBD), and block-circulant (array) codes. To improve the spectral efficiency, we employ a bit-interleaved (BI) LDPC-coded modulation based on the pulse amplitude modulation (PAM). A better bit error rate (BER) performance is achieved by the iteration of extrinsic information between a demapper and LDPC decoder. The simulations show that the LDPC-coded MIMO schemes can operate under a strong atmospheric turbulence and at the same time provide excellent coding gains compared with the transmission of uncoded data. To verify the efficiency of the proposed coding schemes, achievable information rates are computed when the turbulence is modeled by a gamma-gamma distribution.
Efficient Belief Propagation for Early Vision

Markov random field models provide a robust and unified framework for early vision problems such as stereo and image restoration. Inference algorithms based on graph cuts and belief propagation have been found to yield accurate results, but despite recent advances are often too slow for practical use. In this paper we present some algorithmic techniques that substantially improve the running time of the loopy belief propagation approach. One of the techniques reduces the complexity of the inference algorithm to be linear rather than quadratic in the number of possible labels for each pixel, which is important for problems such as image restoration that have a large label set. Another technique speeds up and reduces the memory requirements of belief propagation on grid graphs. A third technique is a multi-grid method that makes it possible to obtain good results with a small fixed number of message passing iterations, independent of the size of the input images. Taken together these techniques speed up the standard algorithm by several orders of magnitude. In practice we obtain results that are as accurate as those of other global methods (e.g., using the Middlebury stereo benchmark) while being nearly as fast as purely local methods.
Challenges in Electronic Cooling—Opportunities for Enhanced Thermal Management Techniques—Microprocessor Liquid Cooled Minichannel Heat Sink

The volumetric heat dissipated by computer equipment at each level of the package from the chip to the chassis is having a tremendous impact on the thermal management of computer equipment. Because of the consumer's insatiable desire for increased performance, the competitive pressures are driving the computer manufacturer to pack as much processor/memory performance within the smallest volume possible. The consumer views high performance in a compact package as a benefit. These market pressures seem to be in direct conflict with the desire to continue to provide air cooling solutions for the foreseeable future. Because of these trends in power and package design, other cooling technologies beside air are now becoming viable, techniques, but each must be weighed with many other factors that influence the cooling technology selected. These factors will be discussed along with two specific IBM server packages and their associated cooling technology employed. Finally a microprocessor liquid cooled minichanne...
Cyclization reactions of ω-tosyloxy-1-alkynyl- and ω-tosyloxy-1-alkenylborates and their ω-halo analogues†

The reaction of trialkylboranes with ω-tosyloxy-1-lithio-1-alkynes can induce transfer of an alkyl group from the boron atom to the alkynyl carbon atom with concomitant formation of four- through six-membered carbocycles via intramolecular displacement of the ω-tosyloxy group. The stereoselectivity of the reaction, however, is low (anti/syn≃1.6–1.7). The corresponding reaction of ω-halo- or ω-tosyloxy-1-alkenylborates also gives exocyclic alkenes via 1,2-migration-cyclization followed by dehydroboration. In the cases of cyclopropanation, cyclopropylcarbinyl-to-homopropargyl rearrangement rather than dehydroboration takes place. Diphenylzirconocene reacts similarly with 6-lithio-5-hexynyl tosylate to give phenylmethylenecyclopentane in 45% yield. On the other hand, attempts to induce a similar migration with phenyl derivatives of Y, V, Cr, and Mn have led to < 5–10% yields of the same cyclization product.
Atmospheres and spectra of strongly magnetized neutron stars

We construct atmosphere models for strongly magnetized neutron stars with surface fields B � 10 12 10 15 G and effective temperatures Teff � 10 6 10 7 K. The atmospheres directly determine the characteristics of thermal emission from isolated neutron stars, including radio pulsars, soft gamma-ray repeaters, and anomalous Xray pulsars. In our models, the atmosphere is composed of pure hydrogen or helium and is assumed to be fully ionized. The radiative opacities include free-free absorption and scattering by both electrons and ions computed for the two photon polarization modes in the magnetized electron-ion plasma. Since the radiation emerges from deep layers in the atmosphere with � > 10 2 g/cm 3 , plasma effects can significantly modify the photon opacities by changing the properties of the polarization modes. In the case where the magnetic field and the surface normal are parallel, we solve the full, angle-dependent, coupled radiative transfer equations for both polarization modes. We also construct atmosphere models for general field orientations based on the diffusion approximation of the transport equations and compare the results with models based on full radiative transport. In general, the emergent thermal radiation exhibits significant deviation from blackbody, with harder spectra at high energies. The spectra also show a broad feature (�E/EBi � 1) around the ion cyclotron resonance EBi = 0.63(Z/A)(B/10 14 G) keV, where Z and A are the atomic charge and atomic mass of the ion, respectively; this feature is particularly pronounced when EBi > 3kTeff. Detection of the resonance feature would provide a direct measurement of the surface magnetic fields on magnetars.
A novel contention-based MAC protocol with channel reservation for wireless LANs

In this paper, we present a novel contention-based medium access control (MAC) protocol, namely, the Channel Reservation MAC (CR-MAC) protocol. The CR-MAC protocol takes advantage of the overhearing feature of the shared wireless channel to exchange channel reservation information with little extra overhead. Each node can reserve the channel for the next packet waiting in the transmission queue during the current transmission. We theoretically prove that the CR-MAC protocol achieves much higher throughput than the IEEE 802.11 RTS/CTS mode under saturated traffic. The protocol also reduces packet collision, thereby saving the energy for retransmission. We evaluate the protocol by simulations under both saturated traffic and unsaturated traffic. Our simulation results not only validate the theoretical analysis on saturated throughput, but also reveal other good features of the protocol. For example, under saturated traffic, both the saturated throughput and fairness measures of the CR-MAC are very close to the theoretical upper bounds. Moreover, under unsaturated traffic, the protocol also achieves higher throughput and better fairness than IEEE 802.11 RTS/CTS.
Results from commissioning the AGS Booster orbit system

This note reports results from the commissioning of three systems in the AGS Booster: the beam position monitor system, which works to a relative accuracy of 0.36 millimeters; the uncorrected Booster orbit, which has quite large excursions; and the passive eddy current correction system, which eliminates all but a few percent of the eddy current dipole effect. >
Fourier domain pump-probe optical coherence tomography imaging of Melanin

We report the development of a two-color Fourier domain Pump-Probe Optical Coherence Tomography (PPOCT) system. Tissue phantom experiments to characterize the system performance demonstrated imaging depths in excess of 725 μm, nearly comparable to the base Optical Coherence Tomography system. PPOCT A-line rates were also demonstrated in excess of 1 kHz. The physical origin of the PPOCT signal was investigated with a series of experiments which revealed that the signal is a mixture of short and long lifetime component signals. The short lifetime component was attributed to transient absorption while the long lifetime component may be due to a mixture of transient absorption and thermal effects. Ex vivo images of porcine iris demonstrated the potential for imaging melanin in the eye, where cancer of the melanocytes is the most common form of eye cancer in adults.
Evidence for neutrino mass: A Decade of discovery

Neutrino mass and mixing are amongst the major discoveries of recent years. From the observation of flavor change in solar and atmospheric neutrino experiments to the measurements of neutrino mixing with terrestrial neutrinos, recent experiments have provided consistent and compelling evidence for the mixing of massive neutrinos. The discoveries at Super-Kamiokande, SNO, and KamLAND have solved the long-standing solar neutrino problem and demand that we make the first significant revision of the Standard Model in decades. Searches for neutrinoless double-beta decay probe the particle nature of neutrinos and continue to place limits on the effective mass of the neutrino. Possible signs of neutrinoless double-beta decay will stimulate neutrino mass searches in the next decade and beyond. I review the recent discoveries in neutrino physics and the current evidence for massive neutrinos.
Electron cloud in the Fermilab Booster

Simulations of the Fermilab Booster reveal a substantial electron-cloud buildup both inside the unshielded combined-function magnets and the beam pipes joining the magnets, when the second-emission yield (SEY) is larger than ~ 1.6. The implication of the electron-cloud effects on space charge and collective instabilities of the beam is discussed.
Texture and wettability of metallic lotus leaves

Superhydrophobic surfaces with the self-cleaning behavior of lotus leaves are sought for drag reduction and phase change heat transfer applications. These superrepellent surfaces have traditionally been fabricated by random or deterministic texturing of a hydrophobic material. Recently, superrepellent surfaces have also been made from hydrophilic materials, by deterministic texturing using photolithography, without low-surface energy coating. Here, we show that hydrophilic materials can also be made superrepellent to water by chemical texturing, a stochastic rather than deterministic process. These metallic surfaces are the first analog of lotus leaves, in terms of wettability, texture and repellency. A mechanistic model is also proposed to describe the influence of multiple tiers of roughness on wettability and repellency. This demonstrated ability to make hydrophilic materials superrepellent without deterministic structuring or additional coatings opens the way to large scale and robust manufacturing of superrepellent surfaces.
A simulation of an income contingent tuition scheme in a transition economy

The paper takes advantage of exceptionally rich longitudinal data on the universe of labor force participants in Slovenia and simulates the working of an income contingent loan scheme that seeks to recover part of schooling costs. The simulations show that under the base variant (where the target cost recovery rate is 20% and the contribution rate is 2%), 55% of individuals would have repaid their entire debt within 20 years; 19% of individuals still would not have repaid any of their debt after 20 years; and the “leakage” of the scheme due to uncollected debt would have been 13.5% of total lending. By piggybacking on existing administrative systems, implementation costs would be minimal, amounting to less than 0.5% of collected debt.
On the ocean heat engine, stiffness of chaotic systems and climate prediction

The oceans are looked on as a heat engine, and the points are made, firstly, that the effect operating this engine is modest, and, secondly, that the engine efficiency is extremely small. It is argued that a parameter, called the “thermal stiffness”, generally increases when certain phenomena: new instabilities, turbulence, noise, etc., appear in thermodynamically forced systems. For the ocean system, this indicates that the temperature rise associated with the greenhouse effect may be overestimated in numerical ocean models which do not include, or do not properly resolve, such phenomena. DOI: 10.1034/j.1600-0889.1991.t01-1-00010.x
Block Compressed Sensing of Images Using Directional Transforms

Recent years have seen significant interest in the paradigm of compressed sensing (CS) which permits, under certain conditions, signals to be sampled at sub-Nyquist rates via linear projection onto a random basis while still enabling exact reconstruction of the original signal. As applied to 2D images, however, CS faces several challenges including a computationally expensive reconstruction process and huge memory required to store the random sampling operator. Recently, several fast algorithms have been developed for CS reconstruction, while the latter challenge was addressed by Gan using a block-based sampling operation as well as projection-based Landweber iterations to accomplish fast CS reconstruction while simultaneously imposing smoothing with the goal of improving the reconstructed-image quality by eliminating blocking artifacts. In this technique, smoothing is achieved by interleaving Wiener filtering with the Landweber iterations, a process facilitated by the relative simple implementation of the Landweber algorithm. In this work, we adopt Gan's basic framework of block-based CS sampling of images coupled with iterative projection-based reconstruction with smoothing. Our contribution lies in that we cast the reconstruction in the domain of recent transforms that feature a highly directional decomposition. These transforms---specifically, contourlets and complex-valued dual-tree wavelets---have shown promise to overcome deficiencies of widely-used wavelet transforms in several application areas. In their application to iterative projection-based CS recovery, we adapt bivariate shrinkage to their directional decomposition structure to provide sparsity-enforcing thresholding, while a Wiener-filter step encourages smoothness of the result. In experimental simulations, we find that the proposed CS reconstruction based on directional transforms outperforms equivalent reconstruction using common wavelet and cosine transforms. Additionally, the proposed technique usually matches or exceeds the quality of total-variation (TV) reconstruction, a popular approach to CS recovery for images whose gradient-based operation also promotes smoothing but runs several orders of magnitude slower than our proposed algorithm.
Microfabricated high-energy particle detector

Abstract An array of high-energy particle detectors, or pixels, has been realized in a silicon substrate using microfabrication technology. A process for fabricating a hemispherical anode, 100 μm in diameter, is described. The pixels are operated in a gaseous chamber where electrons, released when a gas molecule is ionized by an incident high-energy particle, are amplified through a gas avalanche process, and induce a voltage signal at the pixel anode. Test results obtained when operating in the presence of an 55 Fe source indicate that the voltage signal is proportional to the energy of incident γ-rays. The microfabricated array has several advantages over existing gaseous pixel detectors, including high gain at lower applied voltage, reproducible geometry, and potentially lower manufacturing cost.
HOW MUCH FAVORABLE SELECTION IS LEFT IN MEDICARE ADVANTAGE

The health economics literature contains two models of selection, one with endogenous plan characteristics to attract good risks and one with fixed plan characteristics; neither model contains a re...
Synthesis of 1,3-cyclohexadienes by tandem diene–alkyne metathesis: improved procedure

A practical synthesis of 2-substituted 1,3-cyclohexadienes by the cross enyne metathesis between alkynes and 1,5-hexadiene is reported. The isolation of the 1,3-cyclohexadienes has been hampered by the formation of an inseparable triene by-product. The use of a second consecutive cross alkene metathesis to give water-soluble products allowed removal of this by-product. Using this one-pot procedure, a synthesis of cyclohexadienes from simple starting materials was developed. The procedure was used in a three-step synthesis of a functionalized tetrahydroquinoline using Pd(II)-catalyzed chloroacetoxylation (Backvall reaction) for cyclohexadiene functionalization.
Going to a Better School: Effects and Behavioral Responses

This paper applies a regression discontinuity design to the Romanian secondary school system, generating two findings. First, students who have access to higher achievement schools perform better in a (high stakes) graduation test. Second, the stratification of schools by quality in general, and the opportunity to attend a better school in particular, result in significant behavioral responses: (i) teachers sort in a manner consistent with a preference for higher achieving students; (ii) children who make it into more selective schools realize they are relatively weaker and feel marginalized; (iii) parents reduce effort when their children attend a better school.
Grubbs' catalyst in paraffin: an air-stable preparation for alkene metathesis.

A homogeneous mixture of Grubbs' catalyst in paraffin wax was shown to catalyze three important types of metathesis reactions: ring-closing metathesis, alkene dimerization, and alkene cross-metathesis (e.g., 11 → 13). This catalyst preparation demonstrated no loss in catalytic activity after 22 months of storage open to the air.
Prensa y economía: Constitución de una esfera pública en la Venezuela de 1830-47. Debates por la modernización y la libertad de imprenta

En un primer momento se presentaran algunas de las conclusiones a las que llego Jurgen Habermas al estudiar el fenomeno de la esfera publica en Europa. En tal contexto, quedo claramente patentada la relacion entre actores que propugnaban por mayores libertades economicas y comerciales y el empuje de una prensa para defender tales posiciones. Seguidamente, se exploraran algunos pasajes de la historia venezolana comprendida entre 1830 y 1847 que permitan comprender la estrecha relacion mencionada, y en dicho contexto se evaluara la promulgacion de una ley de imprenta en 1839, como parte de un debate modernizador liberal en Venezuela.
Synthetic studies on the perhydropyrrolo[2,1-j]quinoline marine alkaloids lepadiformine and cylindricine C using a 2-azapentadienyl anion cycloaddition. Synthesis of 2,13-diepilepadiformine (or 2-epi-11-deoxycylindricine C)

Abstract Tin-lithium exchange of 13 with n-BuLi produced the 2-azapentadienyl anion 6 (R = CH3), which participated in a [π4s+π2s] cycloaddition reaction with phenyl vinyl sulfide to afford the spirocyclic pyrrolidine 14, which as coverted to 2,13-diepilepadiformine (or 2-epi-11-deoxycylindricine C) 17 by a sequence of steps involving oxidative cleavage of the propenyl side-chain, intramolecular reductive amination, and desulfurization.
Use Of Texture Operators In Segmentation

Computer vision systems applicable for the analysis of complex high resolution aerial images require reliable and robust operators for extracting information from the images. These operators should be able to interrogate the image data and derive meaningful information about the presence of various objects appearing in the scene. In this paper we describe the development of operators that are derived from a texture analysis methodology for performing segmentation of high resolution imagery. The utility of these operators for characterizing various perceptually meaningful properties is demonstrated by performing experimental analysis of urban scenes.
Nanoparticle-Based Electrochemical DNA Detection

Nanoscale architectures of DNA-linked particle networks are attractive for electrical detection of DNA hybridization. This article reviews a variety of new nanoparticle/polynucleotide assemblies for advanced electrical detection of DNA sequences. Recent activity has led to innovative and powerful nanoparticle-based electrochemical DNA hybridization assays based on a variety of detection schemes. Such protocols rely on the use of colloidal gold tags, semiconductor quantum dot tracers, polymeric carrier (amplification) beads, or magnetic (separation) beads. Particularly useful have been protocols based on capturing of metal nanoparticle tracers followed by dissolution and anodic-stripping voltammetric measurement of the metal tag. Remarkable sensitivity is achieved by coupling particle-based amplification units and various amplification processes. The use of nanoparticle tracers for designing multi-target electrochemical coding protocols will also be documented.
Does science advance one funeral at a time

We study the extent to which eminent scientists shape the vitality of their elds by examining entry rates into the elds of 452 academic life scientists who pass away while at the peak of their scientic abilities. Key to our analyses is a novel way to delineate boundaries around scientic elds by appealing solely to intellectual linkages between scientists and their publications, rather than collaboration or co-citation patterns. Consistent with previous research, the ow of articles by collaborators into aected elds decreases precipitously after the death of a star scientist (relative to control elds). In contrast, we nd that the ow of articles by non-collaborators increases by 8% on average. These additional contributions are disproportionately likely to be highly cited. They are also more likely to be authored by scientists who were not previously active in the deceased superstar’s eld. Overall, these results suggest that outsiders are reluctant to challenge leadership within a eld when the star is alive and that a number of barriers may constrain entry even after she is gone. Intellectual, social, and resource barriers all impede entry, with outsiders only entering subelds that oer a less hostile landscape for the support and acceptance of \foreign" ideas.
Systematic statistical comparison of comparative molecular similarity indices analysis molecular fields for computer-aided lead optimization.

Comparative molecular similarity indices analysis (CoMSIA) is a 3D quantitative structure−activity relationship technique used to determine structural and electronic features influencing biological activity. This proves particularly useful for facilitating lead optimization projects. This study aimed to compare CoMSIA models produced using different subsets of the CoMSIA molecular fields (steric, electrostatic, hydrophobic, hydrogen-bond donor, and hydrogen-bond acceptor) in a systematic and statistically valid manner. A total of 23 data sets sourced from the literature were used to compare molecular field contribution and model predictivity using leave-one-out cross-validated R2 values. Predictive ability varied in a highly statistically significant manner depending on the set of CoMSIA molecular fields used. In general, the greater the number of CoMSIA molecular fields included in the analysis, the better the model predictivity was. There is great redundancy in the information contained in the different...
Space And Time Resolved Soft X-Ray Spectra Using X-Ray Transmission Gratings

Gold transmission gratings with 0.3 Am spatial period, 0.6 Am thick have been fabricated and are being used for the spectroscopy of high temperature, laser-produced plasmas. A transmission grating has been coupled with a soft x-ray streak camera, producing the first time resolved (20 psec resolution) continuous x-ray spectrum over the range 0.1 to 1.5 keV from a laser-produced plasma. In addition, a transmission grating has been coupled with a high resolution, Wolter-design x-ray microscope to produce an imaging spectrometer of unprecedented spatial and spectral resolution. In laboratory experiments the imaging spectrometer demonstrated a spectral resolving power, (A/AA) of 200 and a spatial resolution of 1 µm.
Counting permutations by runs

In his Ph.D. thesis, Ira Gessel proved a reciprocity formula for noncommutative symmetric functions which enables one to count words and permutations with restrictions on the lengths of their increasing runs. We generalize Gessel's theorem to allow for a much wider variety of restrictions on increasing run lengths, and use it to complete the enumeration of permutations with parity restrictions on peaks and valleys, and to give a systematic method for obtaining generating functions for permutation statistics that are expressible in terms of increasing runs. Our methods can also be used to obtain analogous results for alternating runs in permutations.
The association between corporate general counsel and firm credit risk

This paper examines whether bond market participants alter their credit risk assessments of firms that appoint the corporate general counsel (GC) to senior management. GCs may place less emphasis on their gatekeeping responsibilities upon appointment to senior management, thus potentially resulting in increased firm credit risk. Using changes in firm-level credit ratings and credit default swap spreads to proxy for changes in credit risk, we find a positive association between GC promotions to senior management and increases in firm credit risk. Additionally, the increased personal liability for GCs under the Sarbanes–Oxley Act only partially mitigates this association.
Ribosome Reinitiation Directs Gene-specific Translation and Regulates the Integrated Stress Response

In the integrated stress response, phosphorylation of eIF2α (eIF2α-P) reduces protein synthesis to conserve resources and facilitate preferential translation of transcripts that promote stress adaptation. Preferentially translated GADD34 (PPP1R15A) and constitutively expressed CReP (PPP1R15B) function to dephosphorylate eIF2α-P and restore protein synthesis. The 5′-leaders of GADD34 and CReP contain two upstream ORFs (uORFs). Using biochemical and genetic approaches we show that features of these uORFs are central for their differential expression. In the absence of stress, translation of an inhibitory uORF in GADD34 acts as a barrier that prevents reinitiation at the GADD34 coding region. Enhanced eIF2α-P during stress directs ribosome bypass of the uORF, facilitating translation of the GADD34 coding region. CReP expression occurs independent of eIF2α-P via an uORF that allows for translation reinitiation at the CReP coding region independent of stress. Importantly, alterations in the GADD34 uORF affect the status of eIF2α-P, translational control, and cell adaptation to stress. These results show that properties of uORFs that permit ribosome reinitiation are critical for directing gene-specific translational control in the integrated stress response.
The Choice of Sterilizing Procedure According to its Potential Reversibility with Microsurgery

Twenty-seven women were evaluated for reversal of previous tubal sterilization in the 2-year span beginning January 1, 1976. Of the thirteen who came to surgery, only seven were able to undergo reanastomosis. Five of these seven had had Pomeroy type ligations and two had ahd "one-burn" electrocoagulation. Six patients who had had "two- or three burn" electrocoagulation did not have sufficient length of fallopian tube remaining. Tubal patency was achieved in 87.5% of those who underwent reanastomosis. The pregnancy rate was 37.5%, with no ectopic pregnancies. Electrocoagulation is not recommended in healthy young women.
No association between plant mating system and geographic range overlap.

Automatic self-fertilization may influence the geography of speciation, promote reproductive isolation between incipient species, and lead to ecological differentiation. As such, selfing taxa are predicted to co-occur more often with their closest relatives than are outcrossing taxa. Despite suggestions that this pattern may be general, the extent to which mating system influences range overlap in close relatives has not been tested formally across a diverse group of plant species pairs.We tested for a difference in range overlap between species pairs for which zero, one, or both species are selfers, using data from 98 sister species pairs in 20 genera across 15 flowering plant families. We also used divergence time estimates from time-calibrated phylogenies to ask how range overlap changes with divergence time and whether this effect depends on mating system.We found no evidence that automatic self-fertilization influenced range overlap of closely related plant species. Sister pairs with more recent divergence times had modestly greater range overlap, but this effect did not depend on mating system.The absence of a strong influence of mating system on range overlap suggests that mating system plays a minor or inconsistent role compared with many other mechanisms potentially influencing the co-occurrence of close relatives.
Trajectory‐based modeling of fluid transport in a medium with smoothly varying heterogeneity

Using an asymptotic methodology, valid in the presence of smoothly varying heterogeneity and prescribed boundaries, we derive a trajectory-based solution for tracer transport. The analysis produces a Hamilton-Jacobi partial differential equation for the phase of the propagating tracer front. The trajectories follow from the characteristic equations that are equivalent to the Hamilton-Jacobi equation. The paths are determined by the fluid velocity field, the total porosity, and the dispersion tensor. Due to their dependence upon the local hydrodynamic dispersion, they differ from conventional streamlines. This difference is borne out in numerical calculations for both uniform and dipole flow fields. In an application to the computational X-ray imaging of a saline tracer test, we illustrate that the trajectories may serve as the basis for a form of tracer tomography. In particular, we use the onset time of a change in attenuation for each volume element of the X-ray image as a measure of the arrival time of the saline tracer. The arrival times are used to image the spatial variation of the effective hydraulic conductivity within the laboratory sample.
Optimal Sovereign Debt Policy with Private Trading: Explaining Allocation Puzzle

This paper studies optimal sovereign debt policy of the government with limited commitment and compare the optimal policies in economies with and without government's capital control. The comparison of optimal sovereign debt policies can rationalize why more financially open market economies show more severe allocation puzzle -- more negative relationship between growth and public capital flows, which is observed in the data.
Robust multi-criteria optimal fuzzy control of discrete-time nonlinear systems

ABSTRACTThis paper presents a novel fuzzy control design of discrete-time nonlinear systems with multiple performance criteria. The purpose behind this work is to improve the traditional fuzzy controller performance to satisfy several performance criteria simultaneously to secure quadratic optimality with an inherent stability property together with a dissipativity type of disturbance reduction. The Takagi–Sugeno-type fuzzy model is used in our control system design. By solving a linear matrix inequality at each time step, the optimal control solution can be found to satisfy mixed performance criteria. The effectiveness of the proposed technique is demonstrated by simulation of the control of the inverted pendulum system on a cart.