cssi/SciSciGPT-SciSciNet huggingface dataset:
Development of continuous detectors for a high resolution animal PET system

We propose a design for a high resolution, gamma-camera style detector that is suitable for use in a positron emission tomograph dedicated to small animal research. Through Monte Carlo simulation we modeled the performance of a detector composed of one 76.2/spl times/76.2/spl times/8 mm thick LSO crystal coupled to a 3" square position sensitive photomultiplier tube (PS-PMT). We investigated the effect of optical coupling compounds, surface treatment and depth of interaction on the quantity (efficiency) and distribution (spread) of scintillation photons reaching the photocathode. We also investigated linearization of the position response. We propose a PET system consisting of fourteen of these detectors in 2 rings, yielding a 16 cm diameter by 15 cm long tomograph. It would operate in 3-D mode subtending a 68% solid angle to the center. The expected spatial resolution is 52 mm, with a system efficiency of /spl sim/10% at the center (200 keV lower threshold) and a singles count rate capability of approximately 10/sup 6/ cps per detector. >
International organizations as collective agents: Fragmentation and the limits of principal control at the World Health Organization:

What factors influence the faithfulness of international organizations (IOs) to mandates assigned to them by member states? Although recent literature treats international organization agents as au...
Towards a chiral gauge theory by deconstruction in AdS5

Author(s): Bhattacharya, Tanmoy; Gupta, Rajan; Martin, Matthew R; Shirman, Yuri; Csaki, Csaba; Terning, John | Abstract: We describe an implementation of a deconstructed gauge theory with charged fermions defined on an interval in five dimensional AdS space. The four dimensional slices are Minkowski, and the end slices support four dimensional chiral zero modes. In such a theory, the energy scales warp down as we move along the fifth dimension. If we augment this theory with localized neutral 4-dimensional Majorana fermions on the low energy end, and implement a Higgs mechanism there, we can arrange the theory such that the lightest gauge boson mode and the chiral mode on the wall at the high energy end are parametrically lighter than all the other states in the theory. If this semiclassical construction does not run into problems at the quantum level, this may provide an explicit construction of a chiral gauge theory. Instanton effects are expected to make the gauge boson heavy only if the resulting effective theory is anomalous.
Optimal Tuner Selection for Kalman Filter-Based Aircraft Engine Performance Estimation

A linear point design methodology for minimizing the error in on-line Kalman filter-based aircraft engine performance estimation applications is presented. This technique specifically addresses the underdetermined estimation problem, where there are more unknown parameters than available sensor measurements. A systematic approach is applied to produce a model tuning parameter vector of appropriate dimension to enable estimation by a Kalman filter, while minimizing the estimation error in the parameters of interest. Tuning parameter selection is performed using a multi-variable iterative search routine which seeks to minimize the theoretical mean-squared estimation error. This paper derives theoretical Kalman filter estimation error bias and variance values at steady-state operating conditions, and presents the tuner selection routine applied to minimize these values. Results from the application of the technique to an aircraft engine simulation are presented and compared to the conventional approach of tuner selection. Experimental simulation results are found to be in agreement with theoretical predictions. The new methodology is shown to yield a significant improvement in on-line engine performance estimation accuracy
Power-Performance Trade-Offs in Nanometer-Scale Multi-Level Caches Considering Total Leakage

In this paper, we investigate the impact of T/sub ox/ and V/sub th/ on power performance trade-offs for on-chip caches. We start by examining the optimization of the various components of a single level cache and then extend this to two level cache systems. In addition to leakage, our studies also account for the dynamic power expended as a result of cache misses. Our results show that one can often reduce overall power by increasing the size of the L2 cache if we only allow one pair of V/sub th//T/sub ox/ in L2. However, if we allow the memory cells and the peripherals to have their own V/sub th/ and T/sub ox/, we show that a two-level cache system with smaller L2s will yield less total leakage. We further show that two V/sub th/ and two T/sub ox/ are sufficient to get close to an optimal solution, and that V/sub th/ is generally a better design knob than T/sub ox/ for leakage optimization, thus it is better to restrict the number of T/sub ox/ rather than V/sub th/ if cost is a concern.
Multicomponent Synthesis of the Medicinally Important Pyrrolo[2,3- d ]Pyrimidine Scaffold (Minireview)

Multicomponent reactions are emerging as a powerful tool in the synthesis of heterocyclic privileged medicinal scaffolds. This highlight describes a recently developed approach to the construction of the medicinally important pyrrolo[2,3-d]pyrimidine scaffold using a one-pot synthesis from commercially available starting materials via novel multicomponent reactions.
UNCERTAINTY AND INSURANCE IN STRATEGIC MARKET GAMES

For perfectly competitive economies under uncertainty, there is a well-known equivalence between a formulation with contingent goods and one with state-specific securities followed by spot markets for goods. In this paper, I examine whether this equivalence carries over to a particular form of imperfect competition. Specifically, I look at three Shapley-Shubik strategic market games: one with contingent commodities, one with Arrow securities traded under imperfect competition and one with Arrow securities traded under perfect competition. First I compare the feasibility constraints of these three games. Then I compare their equilibrium sets. As in Peck and Shell (1989), the only common equilibria between the first and the second game are those which involve no transfer of income across states. However, if the securities markets are competitive, then the set of equilibria of the contingent commodities game and the securities game coincide.
Large-scale non-Gaussianities in the 21-cm background anisotropies from the era of reionization

The brightness temperature fluctuations in the 21-cm background related to the neutral hydrogen distribution provide a probe of the physics related to the era of reionization, when the intergalactic medium changed from being completely neutral to partially ionized. We formulate statistics of 21-cm brightness temperature anisotropies in terms of the angular power spectrum, the bispectrum, and the trispectrum. Using the trispectrum, we estimate the covariance related to the power spectrum measurements and show that correlations resulting from non-Gaussianities are below a per cent, at most. While all-sky observations of the 21-cm background at arcminute-scale resolution can be used to measure the bispectrum with a cumulative signal-to-noise ratio of the order of a few tens, in the presence of foregrounds and instrumental noise related to first-generation interferometers, the measurement is unlikely to be feasible. For most purposes, non-Gaussianities in 21-cm fluctuations can be ignored and the distribution can be described with Gaussian statistics. Because 21-cm fluctuations are significantly contaminated by foregrounds, such as galactic synchrotron or low-frequency radio point sources, the lack of significant non-Gaussianity in the signal suggests that any significant detection of non-Gaussianity could be the result of foregrounds. Similarly, in addition to the frequency information that is now proposed to separate 21-cm fluctuations from foregrounds, if the non-Gaussian structure of foregrounds is known a priori, this additional information could potentially be used to reduce the confusion further.
Development, Discouragement, or Diversion? New Evidence on the Effects of College Remediation

AbstractHalf of all college students will enroll in remedial coursework but evidence of its effectiveness is mixed. Using a regression-discontinuity design with data from a large urban community college system, we make three contributions. First, we articulate three alternative hypotheses regarding the potential impacts of remediation. Second, in addition to credits and degree completion we examine several underexplored outcomes, including initial enrollment, grades in subsequent courses, and post-treatment proficiency test scores. Finally, we exploit rich high school background data to examine impact heterogeneity by predicted dropout risk. We find that remedial assignment does little to develop students’ skills. But we also find little evidence that it discourages initial enrollment or persistence, except for a subgroup we identify as potentially misassigned to remediation. Instead, the primary effect of remediation appears to be diversionary: students simply take remedial courses instead of college-lev...
Implications of electronics constraints for solid-state quantum error correction and quantum circuit failure probability

In this paper we present the impact of classical electronics constraints on a solid-state quantum dot logical qubit architecture. Constraints due to routing density, bandwidth allocation, signal timing and thermally aware placement of classical supporting electronics significantly affect the quantum error correction circuit's error rate (by a factor of ~3–4 in our specific analysis). We analyze one level of a quantum error correction circuit using nine data qubits in a Bacon–Shor code configured as a quantum memory. A hypothetical silicon double quantum dot quantum bit (qubit) is used as the fundamental element. A pessimistic estimate of the error probability of the quantum circuit is calculated using the total number of gates and idle time using a provably optimal schedule for the circuit operations obtained with an integer program methodology. The micro-architecture analysis provides insight about the different ways the electronics impact the circuit performance (e.g. extra idle time in the schedule), which can significantly limit the ultimate performance of any quantum circuit and therefore is a critical foundation for any future larger scale architecture analysis.
Household targeting in practice: The Nicaraguan Red de Protección Social

This article describes the details underlying the targeting of a Nicaraguan anti-poverty program, emphasising the rationale for how it was designed and implemented. It offers, by way of example, a guide for targeting in an anti-poverty program, and highlights some of the potential tradeoffs. It then goes on to present a quantitative assessment of how well the program was able to target poor households. A combination of ad hoc and statistical procedures led to targeting that was effective, with undercoverage rates of 10 per cent or below and leakage rates of 15 per cent or below. This was in spite of the fact that the targeting methodologies used were imprecise at both the household and geographic levels. Copyright © 2008 John Wiley & Sons, Ltd.
Performance of a Swedish deep-bedded feeder pig production system in Iowa

At the Iowa State University Armstrong Research and Demonstration Farm in southwestern Iowa, a Swedish feeder pig production system was studied and demonstrated for 2-1/2 years. The system is based mainly on straw bedding, simple buildings, and intensive management. The system was designed to minimize pig stress and use of subtherapeutic antibiotics in the feed. Gestating and breeding sows were group-housed in a hooped structure with individual feeding stalls. Large round bales of cornstalks were used for bedding. Farrowing, lactation, and nursery phases were housed in a remodeled hog house. Cubicles with rollers and oat straw bedding were used for farrowing. Two groups of Yorkshire × Landrace sows bred to Hampshire boars produced feeder pigs in the system. Conception rates averaged 95%, and litter size averaged 11.3 live pigs/litter. Sows were allowed to select their own bedded farrowing cubicle. Prewean pig mortality, mostly from crushing, was high (29%), occurring primarily in the first 3 days. At 2 weeks of age the cubicles were removed and group lactation occurred. After group lactation the average pig weaning weight was 10.4 kg at 33.9 days of age. At weaning the sows were removed, and the pigs remained in the bedded farrowing/lactation room for 24 additional days. The pigs weighed 24.8 kg at 60 days of age, and overall nursery phase average daily weight gain was 549 g/day. Overall pig health was excellent with no major clinical diseases confirmed. The demonstration exceeded reproductive performance measures of typical small- and mid-sized Iowa farms.
A distributed routing algorithm for multihop packet radio networks with uni- and bi-directional links

Multihop packet radio networks require routing algorithms which are distributed in nature and which have the ability to timely detect changes in the network topology. These changes are mostly changes in connectivity caused by link or node failures and by the relative motion of the nodes. This paper describes and analyzes an adaptive decentralized routing algorithm for packet radio networks. The network connectivity, as perceived by each node, is translated into a graph representation of the network. The proposed routing mechanism then uses a breadth-first search algorithm along the inbound links of such a graph. Unlike most of the algorithms found in the open literature the one proposed here can be used in networks having both uni- and bi-directional radio links. Examples are shown to illustrate the methodology. >
The influence of support-configuration on the acceleration sensitivity of quartz resonator plates

The changes in the thickness-shear resonance frequencies of a circular, rotated Y-cut of quartz plate subject to in-plane steady accelerations was found to be a function of the direction and magnitude of the acceleration, the orientation of the crystal cut, the diameter-to-thickness ratio of the plate, and the numbers and positions of the metal ribbon supports at the edge of the crystal. The purpose of the present study is to investigate how the support configuration will influence the acceleration sensitivity of a resonator. An AT-cut circular quartz plate with four metal ribbon supports is chosen for a systematic parametric study. In order to examine the influence of the supportconfigurations on the frequency changes, the support configuration is changed from a reference configuration by displacing, for instance, one support in increments of 15° counterclockwise while holding the other supports fixed. For each displaced configuration, the frequency changes due to acceleration are computed as a function of the acceleration direction. In the same manner, computations are performed for a total of seven series of configuration variations. Then in each series, the particular support configurations and acceleration directions are identified as giving maximum and zero acceleration effects.
Optimal Learning Patterns for Creativity Generation in a Field

I present a model of optimal learning for creativity generation in a field. The field is defined as a knowledge structure. A creative contribution is based on combining two previously unconnected elements, generating a new element. Individuals may possess private information/intuition about new combinations. Individuals contribute the maximum creative contribution they are able to produce based on the set of elements they have learned. In equilibrium individuals learn different elements, with some degree of overlap, effectively pursuing distinct creative interests. The model illustrates a general approach for analyzing the creative development of fields and, in a broader sense, cultural innovation.
The Noisy Power Method: A Meta Algorithm with Applications

We provide a new robust convergence analysis of the well-known power method for computing the dominant singular vectors of a matrix that we call the noisy power method. Our result characterizes the convergence behavior of the algorithm when a significant amount noise is introduced after each matrix-vector multiplication. The noisy power method can be seen as a meta-algorithm that has recently found a number of important applications in a broad range of machine learning problems including alternating minimization for matrix completion, streaming principal component analysis (PCA), and privacy-preserving spectral analysis. Our general analysis subsumes several existing ad-hoc convergence bounds and resolves a number of open problems in multiple applications: Streaming PCA. A recent work of Mitliagkas et al. (NIPS 2013) gives a space-efficient algorithm for PCA in a streaming model where samples are drawn from a gaussian spiked covariance model. We give a simpler and more general analysis that applies to arbitrary distributions confirming experimental evidence of Mitliagkas et al. Moreover, even in the spiked covariance model our result gives quantitative improvements in a natural parameter regime. It is also notably simpler and follows easily from our general convergence analysis of the noisy power method together with a matrix Chernoff bound. Private PCA. We provide the first nearly-linear time algorithm for the problem of differentially private principal component analysis that achieves nearly tight worst-case error bounds. Complementing our worst-case bounds, we show that the error dependence of our algorithm on the matrix dimension can be replaced by an essentially tight dependence on the coherence of the matrix. This result resolves the main problem left open by Hardt and Roth (STOC 2013). The coherence is always bounded by the matrix dimension but often substantially smaller thus leading to strong average-case improvements over the optimal worst-case bound.
World public debt and real interest rates

Real interest rates appear to have risen in virtually all industrialized countries in the 1980s and 1990s relative to levels that prevailed in earlier decades. There is concern that this may reflect higher public debt, which is crowding out private-sector activity. There has also been increasing international capital market integration, implying that interest rates in any country may be sensitive to global fiscal developments. This paper estimates the effects of such fiscal developments on real interest rates in nine industrial countries. The results imply that the increase in OECD-wide government debt since the late 1970s was a major factor in the rise in real interest rates. Copyright 1999 by Oxford University Press.
Prediction and field validation of traffic oscillation propagation under nonlinear car-following laws

A recent study (Li and Ouyang, 2011) proposed a describing-function approach (DFA) to analytically predict oscillation propagation properties (i.e., dominating frequency and amplitude growth) for a general class of nonlinear car-following laws. This paper presents a new graphic solution approach to DFA and proposes a systematic framework to validate DFA using observed vehicle trajectory data. A set of new empirical measures are defined to extract steady-state traffic properties and oscillation characteristics from vehicle trajectory data. A frequency-domain calibration approach based on DFA is developed to construct a proper nonlinear car-following model that fits these empirical measurements. The analytical DFA predictions of oscillation propagation patterns of the calibrated car-following law are then compared with (i) the observed oscillation properties, and (ii) the simulated oscillation characteristics from the same car-following law. Empirical experiments with real-world trajectory data show that the prediction, the simulation, and the field observation typically match very nicely. This not only validates the analytical prediction approach in the previous study, but also shows that the framework proposed in this paper is capable of calibrating a realistic nonlinear car-following law that reproduces the observed oscillation propagation phenomenon. Our proposed modeling method also brings theoretical analyses and empirical observations into one integrated framework that potentially lays the foundation to understand how nonlinearities in a car-following law affect traffic oscillation evolution, and develop possible counteracting strategies.
The Carceral State and the Crucible of Black Politics: An Urban History of the Rockefeller Drug Laws

While scholars have illuminated the effects of mass incarceration, the origins of the criminal justice policies that produced these outcomes remain unclear. Many explanations obscure as much as they reveal—in great measure because they either ignore or minimize the consequences of crime. Emphasizing the exploitation of white fears, the construction of black criminality, or the political strategies of Republican political elites, prevailing theories ignore black crime victims. In order to excavate the historical roots of the modern carceral state, this study traces the development of New York State's Rockefeller drug laws. Rather than beginning in Albany, this history focuses on Harlem, a community hit hardest by rising crime rates and drug addiction. Drawing upon a variety of primary sources, this study traces how African American activists framed and negotiated the incipient drug problem in their neighborhoods and interrogates the policy prescriptions they attached to indigenously constructed frames. It describes how middle-class African Americans facing the material threats of crime and crime-related problems drew upon the moral content of indigenous class categories to understand these threats and develop policy prescriptions. It reveals how the black middle class shaped the development of this punitive policy and played a crucial role in the development of mass incarceration.
Speeding up Permutation Testing in Neuroimaging

Multiple hypothesis testing is a significant problem in nearly all neuroimaging studies. In order to correct for this phenomena, we require a reliable estimate of the Family-Wise Error Rate (FWER). The well known Bonferroni correction method, while simple to implement, is quite conservative, and can substantially under-power a study because it ignores dependencies between test statistics. Permutation testing, on the other hand, is an exact, non-parametric method of estimating the FWER for a given a-threshold, but for acceptably low thresholds the computational burden can be prohibitive. In this paper, we show that permutation testing in fact amounts to populating the columns of a very large matrix P. By analyzing the spectrum of this matrix, under certain conditions, we see that P has a low-rank plus a low-variance residual decomposition which makes it suitable for highly sub-sampled — on the order of 0.5% — matrix completion methods. Based on this observation, we propose a novel permutation testing methodology which offers a large speedup, without sacrificing the fidelity of the estimated FWER. Our evaluations on four different neuroimaging datasets show that a computational speedup factor of roughly 50 x can be achieved while recovering the FWER distribution up to very high accuracy. Further, we show that the estimated a-threshold is also recovered faithfully, and is stable.
Chiral Amino Siloxy Dienes in the Diels−Alder Reaction: Applications to the Asymmetric Synthesis of 4-Substituted and 4,5-Disubstituted Cyclohexenones and the Total Synthesis of (−)-α-Elemene

Described is a study of the preparation, reactivity, and diastereoselectivity of chiral 1-amino-3-siloxy-1,3-butadienes in the Diels−Alder reaction. These dienes were easily prepared in good yield from the corresponding enantiomerically pure substituted pyrrolidines. All the dienes described underwent cycloadditions readily with several activated dienophiles under mild reaction conditions. An amino siloxy diene containing a C2-symmetric 2,5-diphenylpyrrolidine auxiliary was found to provide high diastereofacial control, even at or above room temperature. Upon hydrolysis of the cycloadducts, 4-substituted and 4,5-disubstituted cyclohexenones were obtained with ee's ranging from 85% to >98%. A simple model based primarily on steric arguments was developed to rationalize and predict the absolute configurations of final products obtained by this sequence. The synthetic utility of the methodology was illustrated through a concise enantioselective synthesis of (−)-α-elemene. The synthesis also served to establi...
Tensor-Entanglement-Filtering Renormalization Approach and Symmetry Protected Topological Order

We study the renormalization group flow of the Lagrangian for statistical and quantum systems by representing their path integral in terms of a tensor network. Using a tensor-entanglement-filtering renormalization approach that removes local entanglement and produces a coarse-grained lattice, we show that the resulting renormalization flow of the tensors in the tensor network has a nice fixed-point structure. The isolated fixedpoint tensors Tinv plus the symmetry group Gsym of the tensors i.e., the symmetry group of the Lagrangian characterize various phases of the system. Such a characterization can describe both the symmetry breaking phases and topological phases, as illustrated by two-dimensional 2D statistical Ising model, 2D statistical loop-gas model, and 1+1D quantum spin-1/2 and spin-1 models. In particular, using such a Gsym,Tinv characterization, we show that the Haldane phase for a spin-1 chain is a phase protected by the time-reversal, parity, and translation symmetries. Thus the Haldane phase is a symmetry-protected topological phase. The Gsym,Tinv characterization is more general than the characterizations based on the boundary spins and string order parameters. The tensor renormalization approach also allows us to study continuous phase transitions between symmetry breaking phases and/or topological phases. The scaling dimensions and the central charges for the critical points that describe those continuous phase transitions can be calculated from the fixed-point tensors at those critical points.
Optimization of 3-phenylpyrazolo[1,5-a]pyrimidines as potent corticotropin-releasing factor-1 antagonists with adequate lipophilicity and water solubility

In our efforts to identify potent CRF(1) antagonists with proper physicochemical properties, a series of 3-phenylpyrazolo[1,5-a]pyrimidines bearing polar groups, such as amino, hydroxyl, methoxy, sulfoxide, were designed and synthesized. Several positions of the core structure were identified, where a polar group was tolerated with slight reduction in receptor binding. NBI 30545 (18n) was found to have good binding affinity and potent antagonistic activity at the human CRF(1) receptor. Moreover, this compound had proper lipophilicity (log D = 2.78) and good solubility in water (>10mg/mL), and exhibited good plasma and brain exposure when given orally.
A parametric study of streaming electrification in a full-scale core-form transformer winding using a network-based model

Streaming electrification remains a problem for large power transformers which require forced-oil cooling. Oil flowing against cellulose insulation surfaces results in the separation of charges from the electrical double layer at the interface. This process can generate hazardous static potentials and volume charge densities in the transformer dielectric system. While streaming electrification has been studied in great detail using small-scale laboratory models, extension of these results to full-scale transformers is rather difficult. This issue has been addressed through the development of a network-based analytical approach which is calibrated against empirical data at the elemental duct level. The model has been utilized to perform a parametric study of streaming electrification in the full-scale high-voltage winding of a core-form transformer. Volume charge densities exiting from each duct in the structure and the local surface potentials are predicted as a function of influent charge, oil volume flow rate, temperature and applied voltage.
Iterative time-limited signal restoration

The purpose of this paper is to show that time-limited restoration of shift-invariant blurred signals can be done by means of fixed-point solutions of contraction mappings, under rather general conditions for the distortion operator. All our results are valid for multidimensional signals. An application of these results to the iterative extrapolation of band-limited discrete images is shown.
Ownership and Control in Outsourcing to China: Estimating the Property-Rights Theory of the Firm

We develop a simple model of international outsourcing and apply it to processing trade in China. Export processing involves a foreign firm contracting with a Chinese factory manager to assemble intermediate inputs into a final product. Whether the same or different parties should have ownership of the processing factory and control over input purchases depends on parameters of the model, which we estimate. We find that multinational firms engaged in export processing in China tend to split factory ownership and input control with local managers: the most common outcome is to have foreign factory ownership but Chinese control over input purchases. Consistent with our model, this pattern is especially prevalent in the southern coastal provinces, where export markets are thickest and contracting costs are lowest.
Neutrino masses and oscillations: triumphs and challenges

The recent progress in establishing the existence of finite neutrino masses and mixing between generations of neutrinos has been remarkable, if not astounding. The combined results from studies of atmospheric neutrinos, solar neutrinos, and reactor antineutrinos paint an intriguing picture for theorists and provide clear motivation for future experimental studies. In this review, we summarize the status of experimental and theoretical work in this field and explore the future opportunities that emerge in light of recent discoveries.
How Attitudes of Important Stakeholder Groups Can Influence Effective Water Quality Management

Abstract Preliminary results of a survey of Lincoln Lake agricultural and non-agricultural watershed residents as well as water quality regulators/specialists suggests discrepancies exists in different groups perceptions of water quality, the sources of water pollution, and the roles of local, county, state and federal officials in meeting water quality objectives. JEL codes: Q25, Q53, Q59 Introduction The Lincoln Lake watershed in Northwest Arkansas is a rapidly growing area that is home to animal agriculture, urban dwellers and industry. The watershed is a sub-watershed of the Illinois River basin that expands across Northwest Arkansas and Northeastern Oklahoma (see Figure 1). This area is home to thousands of poultry farms and pastures that produce abundant forage for numerous beef and dairy cattle. While animal manure has been used effectively as a fertilizer for pasture grasses, concerns exist that that excess land applications of animal manure can lead to surface and ground water pollution due to increased runoff of nitrogen (N) and phosphorus (P), sediment, and pathogens (e.g., Edwards et al., 1996). As surface waters cross state and county borders, disputes arise, not only across state lines but among agricultural landowners, poultry producers, environmentalists, and other stakeholders within the watershed itself. Stakeholders generally feel unrepresented in the policy process. As a result, they turn to the courts to address their disputes while policies that effectively address concerns have yet to materialize. Debate exists as to whether stakeholder involvement in the policy process can improve policy decisions (Yosie and Herbst, 1998). For instance, Kiker et al. (2005) argue that
Electrophilic Reactions of Phenols

1 Introduction 2 Friedel–Crafts Alkylation 3 Friedel–Crafts Acylations 4 Nitration and Nitrosation 5 Fries and Related Rearrangements 6 Electrophilic Halogenation 7 Phenol–Dienone Rearrangements Keywords: electrophilic reactions of phenols; Friedel–Crafts alkylation; phenolic functional groups; alkylations under supercritical conditions; hexamethylenetetramine-trifluoroacetic acid system; Friedel–Crafts acylations; nitrous acid nitrosation; Lewis acid catalyzed Fries rearrangements
Antenna selection for space-time coded systems with imperfect channel estimation

This paper studies the performance of antenna selection (AS) for space-time (ST) coded systems with noisy channel estimates. For coherent AS systems over Rayleigh flat fading channels, we derive the pairwise error probability (PEP) in the presence of imperfect channel estimation, where the channel is estimated using training insertion and minimum mean square error (MMSE) estimation. Multiplexed training is employed, where the antennas are multiplexed to the small number of RF chains available in the AS system. AS is performed only at the receiver, using the maximum estimated channel power selection rule. Both the maximum likelihood (ML) decoder taking into account the channel estimation error, and the minimum distance decoder are considered, and full diversity gain is shown to be preserved for both cases. Based on the derived training-based PEP, the effective SNR and the coding gain loss due to training are quantified for square unitary and orthogonal codes. The optimal power allocation between the training and data symbols is obtained by minimizing the PEP. For AS systems employing orthogonal designs, we further derive the exact PEP expression in closed-form. We also show that when square unitary training is employed, AS using the norm of MMSE channel estimates is equivalent to AS using the norm (power) of the received signal. Exploiting this fact, we propose an alternate training scheme which avoids multiplexing, has higher spectral efficiency, and better performance compared to the multiplexed training scheme. Simulations are shown to validate our analysis
Viewpoint: metallurgical aspects of powder bed metal additive manufacturing

Metal additive manufacturing has emerged as a new manufacturing option for aerospace and biomedical applications. The many challenges that surround this new manufacturing technology fall into several different categories. The paper addresses one of these categories, the physical mechanisms that control the additive manufacturing process. Physical mechanisms control the effects of processing parameters on microstructures and properties of additively manufactured parts. Some mechanisms might not have been recognized, yet, and for those that are currently known, detailed quantitative predictions have to be established. The physical mechanisms of metal additive manufacturing are firmly grounded in metallurgy, branching into laser physics and the physics of granular materials. Powder bed additive manufacturing is described from the powder storage to post-processing and elements of metallurgy are highlighted that are relevant for the different aspects of the additive manufacturing process. These elements include the surface reactions on powder particles, the heating and melting behavior of the powder bed, solidification, and post-processing. This overview of the different metallurgical aspects to additive manufacturing is intended to help guide research efforts and it will also serve as a snapshot of the current understanding of powder bed additive manufacturing.
A new strategy toward indole alkaloids involving an intramolecular cycloaddition/rearrangement cascade

The intramolecular Diels−Alder reaction between an amidofuran moiety tethered onto an indole component was examined as a strategy for the synthesis of Aspidosperma alkaloids. Furanyl carbamate 23 was acylated using the mixed anhydride 26 to provide amidofuran 22 in 68% yield. Further N-acylation of this indole furnished 27 in 88% yield. Cyclization precursors were prepared by removing the carbamate moiety followed by N-alkylation with the appropriate alkyl halides. Large substituent groups on the amido nitrogen atom causes the reactive s-trans conformation of the amidofuran to be more highly populated, thereby facilitating the Diels−Alder cycloaddition. The reaction requires the presence of an electron-withdrawing substituent on the indole nitrogen in order for the cycloaddition to proceed. Treatment of N-allyl-bromoenamide 48 with n-Bu3SnH/AIBN preferentially led to the 6-endo trig cyclization product 50, with the best yield (91%) being obtained under high dilution conditions. The initially generated cyc...
An improvement to the bit stuffing algorithm

The bit stuffing algorithm is a technique for coding constrained sequences by the insertion of bits into an arbitrary data sequence. This approach was previously introduced and applied to (d,k) constrained codes. Results show that the maximum average rate of the bit stuffing code achieves capacity when k=d+1 or k=/spl infin/, while it is suboptimal for all other (d,k) pairs. Furthermore, this technique was generalized to produce codes with an average rate that achieves capacity for all (d,k) pairs. However, this extension results in a more complicated scheme. This correspondence proposes a modification to the bit stuffing algorithm that maintains its simplicity. We show analytically that the proposed algorithm achieves improved average rates over bit stuffing for most (d,k) constraints. We further determine all constraints for which this scheme produces codes with an average rate equal to the Shannon capacity.
Monoalkylation of C60 and C70 with Zn and active alkyl bromides.

We report a convenient and simple solution-phase electron-transfer reaction of C60 with zinc and α-bromoacetonitrile, α-bromo acetate esters, allyl bromide, benzyl bromide and α-bromo ketones in DMF, with which different types of monoalkylated C60 derivatives can be prepared. When this method is employed with C70, 2-carbomethoxymethyl-1,2-dihydro[70]fullerene (isomer 5a) is produced as one of the two 1,2-monoalkylated C70 isomers, together with the first 5,6-monoalkylated C70 derivative.
Design, Synthesis, and Biological Activity of Novel Triazole Amino Acids Used To Probe Binding Interactions Between Ligand and Neutral Amino Acid Transport Protein SN1

Novel triazole amino acids were synthesized as probes to investigate ligand-protein binding interactions of the neutral amino acid transporter SN1. The bonding hypothesis to be tested was that the side chains of endogenous substrates are acting as H-bond acceptors. Although limited inhibition of (3)H-L-glutamine uptake by SN1 expressing oocytes was observed, the synthetic compounds show a trend that suggests a hydrogen bond interaction just outside the endogenous ligand binding pocket.
Retraction Note: Chronic neuroinflammation and cognitive impairment following transient global cerebral ischemia: role of fractalkine/CX3CR1 signaling

Although neuroinflammation has been studied extensively in animal models of cerebral ischemia, their contrasting functions are still not completely understood. A major participant in neuroinflammation is microglia and microglial activation usually regulated by the chemokine CX3CL1 (fractalkine) and its receptor, CX3CR1. Here, we examined the involvement of CX3CR1 on ischemia-induced chronic neuroinflammation and cognitive function using small interfering RNA (siRNA). Forty adult male Wistar rats were included in the study and received either ischemia or sham surgery then were randomized to receive either CX3CR1 siRNA or scrambled RNA as control starting at 7 days after reperfusion. Behavioral testing commenced 28 days after siRNA delivery and all rats were euthanized after behavioral testing. Our data showed that: (i) transient global cerebral ischemia significantly decreased fractalkine/CX3CR1 signaling in the hippocampus; (ii) inhibition of CX3CR1 function exacerbated the ischemia-induced chronic increase in microglial activation and pro-inflammatory cytokine levels; (iii) inhibition of CX3CR1 function worsened ischemia-induced chronic cognitive impairment; (iv) inhibition of CX3CR1 function in sham rats resulted in increased IL-1β expression and impaired behavioral performance. However, no significant effect of CX3CR1 on ischemia-induced neurodegeneration was seen. The present study provides important insight to understanding the involvement of CX3CR1 in chronic neuroinflammation and cognitive impairment.
Evaluation of Visual Performance When Using Incandescent, Fluorescent, and LED Machine Lights in Mesopic Conditions

This experiment investigated the effects of different machine-mounted area lighting technologies on visual performance in a simulated underground mine environment. The primary objective was to conduct a comparative evaluation of the lighting technologies based on the visual performance of 36 human subjects in a simulated underground mine environment. Incandescent (Incand), fluorescent (Fluor), and light-emitting diode (LED) technologies were used to create four lighting combinations. Visual performance was quantified for the detection of movement in the peripheral field of view and the identification of ground hazards. Measurements were made of the speed (response time measured in milliseconds), the accuracy (the number of targets and objects missed), and the subjective discomfort rating of the glare experienced for each lighting combination. A secondary objective explored the effects of aging on visual performance. The results indicate that lighting combinations which consisted of LED area lights significantly improved visual performance for the detection of hazards found in the peripheral field of view, as well as those found on the ground. They furthermore indicate that age plays a significant role in visual performance.
Detecting cusps and inflection points in curves

In many applications it is desirable to analyze parametric curves for undesirable features like cusps and inflection points. Previously known methods to analyze such features are limited to cubics and in many cases are for planar curves only. We present a general purpose technique to detect cusps in polynomial or rational space curves of arbitrary degree. If a curve has no cusp in its defining interval, it has a regular parametrization and our algorithm computes that. The regular parametrizations are used to analyze for inflection points.
Macroeconomic Models for Monetary Policy: A Critical Review from a Finance Perspective

We provide a critical review of macroeconomic models used for monetary policy at central banks from a finance perspective. We review the history of monetary policy modeling, survey the core monetar...
The networked common goods game

We introduce a new class of games called the networked common goods game (NCGG), which generalizes the well-known common goods game [12]. We focus on a fairly general subclass of the game where each agent's utility functions are the same across all goods the agent is entitled to and satisfy certain natural properties (diminishing return and smoothness). We give a comprehensive set of technical results listed as follows. - We show the optimization problem faced by a single agent can be solved efficiently in this subclass. The discrete version of the problem is however NP-hard but admits a fully polynomial time approximation scheme (FPTAS). - We show uniqueness results of pure strategy Nash equilibrium of NCGG, and that the equilibrium is fully characterized by the structure of the network and independent of the choices and combinations of agent utility functions. - We show NCGG is a potential game, and give an implementation of best/better response Nash dynamics that lead to fast convergence to an e-approximate pure strategy Nash equilibrium. - Lastly, we show the price of anarchy of NCGG can be as large as Ω(n1-e) (for any e ≥ 0), which means selfish behavior in NCGG can lead to extremely inefficient social outcomes.
Citizen Science on Your Smartphone: An ELSI Research Agenda

The prospect of newly-emerging, technology-enabled, unregulated citizen science health research poses a substantial challenge for traditional research ethics. Unquestionably, a significant amount of research ethics study is needed to prepare for the inevitable, widespread introduction of citizen science health research. Using the case study of mobile health (mHealth) research, this article provides an ethical, legal, and social implications (ELSI) research agenda for citizen science health research conducted outside conventional research institutions. The issues for detailed analysis include the role of IRBs, recruitment, inclusion and exclusion criteria, informed consent, confidentiality and security, vulnerable participants, incidental findings, and publication and data sharing.
The Spatiotemporal Structure of Diabatic Processes Governing the Evolution of Subantarctic Mode Water in the Southern Ocean

AbstractA coupled ice–ocean eddy-permitting Southern Ocean State Estimate (SOSE) for 2008–10 is used to describe and quantify the processes forming and destroying water in the Subantarctic Mode Water (SAMW) density range (σθ = 26.7–27.2 kg m−3). All the terms in the temperature and salinity equations have been diagnosed to obtain a three-dimensional and time-varying volume budget for individual isopycnal layers. This study finds that air–sea buoyancy fluxes, diapycnal mixing, advection, and storage are all important to the SAMW volume budget. The formation and destruction of water in the SAMW density range occurs over a large latitude range because of the seasonal migration of the outcrop window. The strongest formation is by wintertime surface ocean heat loss occurring equatorward of the Subantarctic Front. Spring and summertime formation occur in the polar gyres through the freshening of water with σθ > 27.2 kg m−3, with an important contribution from sea ice melt. Further buoyancy gain by heating is ac...
The Natural Approach to Language Teaching: An Update.

philosophy of language teaching which I called the "Natural Approach" (NA).1 My suggestions at that time were the outgrowth of experience with Dutch and Spanish classes in which the target languages were taught to beginners whose native language was English. Since then the NA has been used in primary, secondary, and adult ESL classes, as well as in secondary, university, and adult Spanish, French, and German classes. During these five years of experimentation we have concentrated on the development of teaching techniques to implement the original proposals. This paper has two purposes: 1) to discuss the underlying assumptions of the 1977 paper in light of recent research in second language acquisition and learning, as well as from personal experience in the classroom; and 2) to suggest specific techniques for implementing the NA in second or foreign language class-