cssi/SciSciGPT-SciSciNet huggingface dataset:
Suzuki Cross-Coupling Reactions Catalyzed by Palladium Nanoparticles in Aqueous Solution

Palladium nanoparticles stabilized by poly(N-vinyl-2-pyrrolidone) (PVP) are efficient catalysts for the Suzuki reactions in aqueous medium. The time dependence of the fluorescence intensity of the biphenyl product in the reaction between iodobenzene and phenylboronic acid is used to determine the initial rate of the catalytic reaction. The initial rate depends linearly on the concentration of Pd catalyst, suggesting that the catalytic reaction occurs on the surface of the Pd nanoparticles.
Actinide-based single-molecule magnets

Actinide single-molecule magnetism has experienced steady growth over the last five years since the first discovery of slow magnetic relaxation in the mononuclear complex U(Ph2BPz2)3. Given their large spin–orbit coupling and the radial extension of the 5f orbitals, the actinides are well-suited for the design of both mononuclear and exchange-coupled molecules, and indeed at least one new system has emerged every year. By some measures, the actinides are already demonstrating promise for one day exceeding the performance characteristics of transition metal and lanthanide complexes. However, much further work is needed to understand the nature of the slow relaxation in mononuclear actinide complexes, as well as the influence of magnetic exchange on slow relaxation in multinuclear species. This perspective seeks to summarize the successes in the field and to address some of the many open questions in this up and coming area of research.
Economic growth in Latin America

Abstract This paper studies growth determinants in 12 Latin American countries during the period 1950–1985. In a growth accounting framework, the share of labor in income is found to be lower in the sample group than in developed countries, while factor productivity growth accounts for a larger proportion of growth in the fastest growing countries. Using panel data, macroeconomic stability is found to play, in addition to investment (physical and human), a crucial role in growth. To a lesser extent, growth is negatively correlated with government consumption and political instability. The terms of trade appear to have no significant effect on growth.
Near-optimal output feedback regulation of ill-conditioned linear systems

A two-time scale approximation for the linear quadratic optimal output feedback regulator program is examined. Necessary conditions for optimality, as well as an algorithm for computing locally near-optimal gains are derived. If it is assumed that the slow and fast subsystem initial conditions are uniformly distributed, optimal gains for the two-time-scale problem provide a second-order approximation to optimal closed-loop performance in the unperturbed system. This is verified with a numerical example. >
Toward Epoch of Reionization Measurements with Wide-Field Radio Observations

This paper explores the potential for statistical epoch of reionization (EOR) measurements using wide-field radio observations. New developments in low-frequency radio instrumentation and signal processing allow very sensitive EOR measurements, and the analysis techniques enabled by these advances offer natural ways of separating the EOR signal from the residual foreground emission. This paper introduces the enabling technologies and proposes an analysis technique designed to make optimal use of the capabilities of next-generation low-frequency radio arrays. The observations we propose can directly observe the power spectrum of the EOR using relatively short observations and are significantly more sensitive than other techniques that have been discussed in the literature. For example, in the absence of foreground contamination the measurements we propose would produce five 3 � power spectrum points in 100 hr of observation with only 4 MHz bandwidth with LOFAR for simple models of the high-redshift 21 cm emission. The challenge of residual foreground removal may be addressed by the symmetries in the three-dimensional (two spatial frequencies and radio frequency) radio interferometric data. These symmetries naturally separate the EOR signal from most classes of residual unsubtracted foreground contamination, including all foreground continuum sources and radio line emission from the Milky Way. Subject heading gs: cosmology: observations — early universe — radio lines: general
Scaling laws, transient times and shell effects in helium induced nuclear fission

Fission excitation functions have been studied over the last decades and they have shown a dramatical variation from nucleus to nucleus over the periodic table[1,2,3]. Some of these differences can be understood in terms of a changing liquid-drop fission barrier, others are due to strong shell effects which occur e.g. in the neighborhood of the double magic numbers Z=82 and N=126. Further effects may be associated with pairing and the angular momentum dependence of the fission barrier[4,5,6]. With the availability of newer accelerators, several studies have investigated heavy ion and high energy light particle induced fission [5]. These reactions show a large deposit of energy, mass and most important angular momentum. The strong dependence of the fission probability on the latter quantity makes comparisons to liquid drop model calculations difficult. The problem of extensive angular momentum, energy and mass transfer can be minimized by the use of light ion induced fission at moderate bombarding energies. In contrast to heavy ion reactions, it has been shown that the fission barriers extracted from low energy light ion induced fission reactions differ only slightly from liquid drop predictions[7,8].
A CMOS oversampling bandpass cascaded D/A converter with digital FIR and current-mode semi-digital filtering

An oversampling bandpass digital-to-analog converter has been designed so as to eliminate the carrier leak and in-band SNR degradation that accompany I and Q channel mismatch in wireless transmitters. The converter combines a cascaded noise-shaping sigma-delta (/spl Sigma//spl Delta/) modulator with digital finite impulse response (FIR) and mixed-signal semi-digital filters that attenuate out-of-band quantization noise. The performance of the converter in the presence of current source mismatch has been improved through the use of bandpass data weighted averaging. An experimental prototype of the converter, integrated in a 0.25-/spl mu/m CMOS technology, provides 83 dB of dynamic range for a 6.25-MHz signal band centered at 50 MHz, and suppresses out-of-band quantization noise by 38 dB.
Local responses to marine conservation in Zanzibar, Tanzania

While terrestrial parks and reserves have existed in Tanzania since colonial times, marine protected areas are a much newer endeavor in natural resource conservation. As the importance of marine conservation came to the international forefront in the 1990s, Tanzania experienced a rapid establishment and expansion of marine parks and protected areas. These efforts were indeed crucial to protecting the country’s marine resource base, but they also had significant implications for the lives and fishing patterns of local artisanal fishermen. Terrestrial protected areas in Tanzania have historically been riddled with conflict and local contestation, bringing about numerous debates on the best ways to involve rural residents in conservation planning efforts to establish new “community-based conservation” programs. However, because marine protected areas do not have the same history as terrestrial conservation in Tanzania, marine conservation programs present a new opportunity to pilot innovative techniques to involve local communities in protecting and managing their natural resources. The islands of Zanzibar are home to four community-oriented marine protected areas, each of which is sponsored by an external agency, and each of which involves some form of local community component. However, a number of issues arise when working at the community level, requiring nuanced attention to a variety of local factors. The Menai Bay program in southern Zanzibar provides an excellent example of the complexity of factors involved, which can result in dramatically different village-level responses to a single program. These factors include, but are not limited to, differences in geography and infrastructure, the potential for tourism development and alternative sources of income, pre-existing community structures within each village, and the relationship of conservation program managers to the Zanzibari government. While these factors are complex and difficult to predict, it is essential that conservation programs take them into account when trying to establish community-based marine conservation programs that will be sustainable in the long-term.
SENSTRAC: scalable querying of sensor networks from mobile platforms using tracking-style queries

Future applications running on mobile platforms will sometimes need to query sensors and track sensor data over time. This paper proposes a novel, but natural, solution to querying sensors from mobile platforms, based on the publish-subscribe paradigm. Various options are discussed and the most promising one is included into an implementation. Our evaluation focuses on scalability.
Aggregation functions for engineering design trade-offs

Abstract The choice of an aggregation function is a common problem in multi-attribute decision making (MADM) systems. The Method of Imprecision (MoI) is a formal theory for the manipulation of preliminary design information that represents preferences among design alternatives with the mathematics of fuzzy sets. The MoI formulates the preliminary design problem as a MADM problem. To date, two aggregation functions have been developed for the MoI, one representing a compensating strategy and one a non-compensating strategy. Much of the prior fuzzy sets research on aggregation functions has been inappropriate for application to engineering design. In this paper, the selection of an aggregation function for MADM schemes is discussed within the context of the MoI. The general restrictions on design-appropriate aggregation functions are outlined, and a family of functions, modeling a range of trade-off strategies, is presented. The results are illustrated with an example.
Direct sale of information when precision is unobservable

This paper studies the incentives of an information seller to produce precise information in a setting where precision is not observable and investors with rational expectations can extract information from the equilibrium asset price. I show that the seller can verify her unknown precision by employing a nonlinear contract proposed by Bhattacharya and P‡eiderer (1985). Although precision is not observable, buyers can perfectly deduce it from the contract. Apart from incentives to produce precise information and reveal it truthfully, the nonlinear contract also insures against the portfolio risk of information buyers and causes them to trade aggressively. For a given precision, this increases the extent of information that is built into the equilibrium asset price. The seller’s equilibrium fee depends on (i) her inferred precision (ii) the value of portfolio insurance for buyers and (iii) the extent of information that leaks from the equilibrium asset price.
The Relative Sophistication of Chinese Exports

China's exports have grown dramatically over the last three decades in large part due to its rapid penetration of new product markets. To help address the implications of this growth for developed economies, this paper gauges the relative sophistication of Chinese exports along two dimensions. First, I measure China's export overlap with developed countries by comparing the set of products China exports to the United States with the bundle of products exported by the OECD. Second, I compare Chinese and other countries’ exports within product markets in terms of the price they receive in the US market. While China's export overlap with the OECD is much greater than one would predict given its low wages, the prices that US consumers are willing to pay for China's exports are substantially lower than the prices they are willing to pay for OECD exports. This fact, as well as the increase in the ‘OECD premium’ over time, suggests that competition between China and the world's most developed economies may be less direct than their product-mix overlap implies. It may also reflect efforts by developed-country firms to compete with China by dropping their least sophisticated offerings and moving up the quality ladder. — Peter K. Schott
Impedance and polarization characteristics of H and IHI slot antennas

Slot antennas can be end loaded to tune input impedance for use with active devices and to decrease overall slot length at a given resonant frequency. Cross polarization and impedance of end-loaded slots in an H configuration are analyzed. For an H antenna of approximately equal height and width, D-plane cross polarization was found to be -20 dB, and the resonant frequency decreased by 34% over a slot with a length equal to the width of the H. The cross polarization can be reduced with our new IHI configuration, which is introduced. The impedance at the second resonance can be tuned over a range of 26-82 /spl Omega/.
Wireless resource management using genetic algorithm for mobiles equilibrium

We propose an algorithm for controlling mobile users transmitter power and information bit rate cooperatively in CDMA networks. The active component of this scheme is called genetic algorithm for mobiles equilibrium (GAME). Based an an evolutionary computational model, the base station tries to achieve an adequate equilibrium between its users. Thereof each mobile can send its traffic with a suitable power to support it over the different path losses and interference. In the mean time, its battery life is being preserved while limiting the interference seen by neighbors. This optimization is based on each user traffic, required signal quality, the channel characteristics and users spatial distribution. A significant enhancement in signal quality and power level has been noticed through several experiments.
Modular typechecking for hierarchically extensible datatypes and functions

One promising approach for adding object-oriented (OO) facilities to functional languages like ML is to generalize the existing datatype and function constructs to be hierarchical and extensible, so that datatype variants simulate classes and function cases simulate methods. This approach allows existing datatypes to be easily extended with both new operations and new variants, resolving a longstanding conflict between the functional and OO styles. However, previous designs based on this approach have been forced to give up modular typechecking, requiring whole-program checks to ensure type safety. We describe Extensible ML (EML), an ML-like language that supports hierarchical, extensible datatypes and functions while preserving purely modular typechecking. To achieve this result,EML's type system imposes a few requirements on datatype and function extensibility, but EML is still able to express both traditional functional and OO idioms. We have formalized a core version of EML and proven the associated type system sound, and we have developed a prototype interpreter for the language.
Micro-flex mirror and instability actuation technique

This paper reports on the design and fabrication of a surface micromachined mirror system which is capable of producing the required moments to rotate a mirror structure out of the plane of fabrication. The planar structures created by surface micromachining present difficulties with developing a sufficient moment to move structures out of the x-y plane when actuated by those same planar structures. This is due to the short moment arms (in thickness direction z) that can be created in the fabrication process. The instability actuation technique reported here has general application to moving 2-dimensional structures up and out of the plane of their original fabrication. This technique can be applied to "build" truly 3-dimensional structures from a nearly 2-dimensional fabrication process. Surface micromachining can now be considered a 3-dimensional process where 3-dimensional structures are built by raising up structures by the instability actuation technique and making appropriate mechanical interconnections.
Detailed Analysis of Raim Performance for ADS‐B Separation Error

Performance standards are currently being developed for GPS-based Automatic Dependent Surveillance Broadcast (ADs-B). Of concern is the possibility of significant error in apparent aircraft separation when the ADS-B position reports are based on slightly different sets of satellites, but a fault on a common satellite goes undetected by RAIM algorithms in both aircraft. Performance of solution-separation RAIM in the above circumstance is analyzed in depth. Dependence of the conditional separation error risk on the correlation between the two RAIM decision statistics is derived in detail. The total risk (including the prior probability of satellite fault) is evaluated to compare RAIM-based ADS-B performance with current surveillance radar for achieving the 3.0 nmi separation standard in the terminal area. The analysis considers two prospective values (0.5 nmi and 0.6 nmi) of the RAIM Horizontal Alert Limit (HAL) corresponding to the radius of containment (R c ) associated with ADS-B position reports.
On the Structure of Gold-Leaf, and the Absorption Spectrum of Gold

GoLD-leaf, as seen under the microscope by transmitted light, presents a remarkable appearance which seems to have been hitherto either not at all or only slightly noticed. The colour of the transmitted light is bluish-green, unless silver in considerable proportion be alloyed with the gold; in this latter case the colour is purplish-blue. The amount of light transmitted is, as might be expected, not uniform, the thickness of the gold film varying within very small areas of the surface. All this is well known to anyone who has ever looked through a bit of the leaf. But, in addition, numerous black lines are visible under very moderate amplification, ramifying irregularly over the surface, here and there showing some tendency to parallelism, but for the most part running into each other in the most irregular way. Fig. 1 illustrates th is; it is a microscopic photograph of ordinary commercial goldleaf, taken with an amplification of 75 diameters, and a distance from the eye-piece to the camera plate of 378 millims.
O2 and N2O activation by Bi-, Tri-, and tetranuclear Cu clusters in biology.

Copper-cluster sites in biology exhibit unique spectroscopic features reflecting exchange coupling between oxidized Cu’s and e− delocalization in mixed valent sites. These novel electronic structures play critical roles in O2 binding and activation for electrophilic aromatic attack and H-atom abstraction, the 4e−/4H+ reduction of O2 to H2O, and in the 2e−/2H+ reduction of N2O. These electronic structure/reactivity correlations are summarized below.
Shaping regularization in geophysical-estimation problems

Regularization is a required component of geophysical-estimation problems that operate with insufficient data. The goal of regularization is to impose additional constraints on the estimated model. I introduce shaping regularization, a general method for imposing constraints by explicit mapping of the estimated model to the space of admissible models. Shaping regularization is integrated in a conjugate-gradient algorithm for iterative least-squares estimation. It provides the advantage of better control on the estimated model in comparison with traditional regularization methods and, in some cases, leads to a faster iterative convergence. Simple data interpolation and seismic-velocity estimation examples illustrate the concept.
Ho-Kashyap advanced pattern-recognition heteroassociative processors

We review different categories of associative processors with attention to the properties of their key and recollection vectors, the test procedures to be used and the performance measures to be used to compare various associative processors. We review new pseudoinverse and Ho-Kashyap associative processors and robust versions of each. Q uantitative data is presented on the performance of these new pattern recognition associative processors. In all cases we show significant improvement over prior data with M >> N (M is the number of key/recollection vectors pairs stored and N is the dimensionality of the input key vector). Quantization of the number of analog levels and comparisons of various recollection vector encodings are considered.
Supersonic/Hypersonic Laminar Heating Correlations for Rectangular and Impact-Induced Open and Closed Cavities

Impact and debris damage to the Space Shuttle Orbiter Thermal Protection System tiles is a random phenomenon, occuring at random locations on the vehicle surface, resulting in random geometrical shapes that are exposed to a definable range of surface flow conditions. In response to the 2003 Final Report of the Columbia Accident Investigation Board, wind tunnel aeroheating experiments approximating a wide range of possible damage scenarios covering both open and closed cavity flow conditions were systematically tested in hypersonic ground based facitilies. These data were analyzed and engineering assessment tools for damage-induced fully-laminar heating were developed and exercised on orbit. These tools provide bounding approximations for the damaged-surface heating environment. This paper presents a further analysis of the baseline, zero-pressure-gradient, idealized, rectangular-geometry cavity heating data, yielding new laminar correlations for the floor-averaged heating, peak cavity endwall heating, and the downstream decay rate. Correlation parameters are derived in terms of cavity geometry and local flow conditions. Prediction Limit Uncertainty values are provided at the 95%, 99% and 99.9% levels of significance. Non-baseline conditions, including non-rectangular geometries and flows with known pressure gradients, are used to assess the range of applicability of the new correlations. All data variations fall within the 99% Prediction Limit Uncertainty bounds. Importantly, both open-flow and closed-flow cavity heating are combined into a single-curve parameterization of the heating predictions, and provide a concise mathematical model of the laminar cavity heating flow field with known uncertainty.
Status of LBL/LLNL FEL research for two beam accelerator applications

The authors review the status of free-electron laser (FEL) research being conducted at LBL (Lawrence Berkeley Laboratory) and LLNL (Lawrence Livermore National Laboratory) as part of a broader program of research on two-beam accelerators (TBAs). Induction accelerator-driven FELs for use as power sources for high-gradient accelerators are discussed, along with preliminary cost estimates for this type of power source. A promising new version of an FEL/TBA is described. >
The Enantioselective Synthesis of α-Amino Acids by Phase-Transfer Catalysis with Achiral Schiff Base Esters

The development and application of chiral phase-transfer catalysis (PTC) for the enantioselective synthesis of optically active α-amino acid derivatives using achiral Schiff base esters developed in the author's laboratory and by others is reviewed. Phase-transfer catalysts derived from the Cinchona alkaloids have been exploited as inexpensive and attractive organocatalysts in the chiral PTC process. The recent evolution and use of these and other catalytic systems is described.
Network Coding for Computing: Cut-Set Bounds

The following network computing problem is considered. Source nodes in a directed acyclic network generate independent messages and a single receiver node computes a target function f of the messages. The objective is to maximize the average number of times f can be computed per network usage, i.e., the “computing capacity”. The network coding problem for a single-receiver network is a special case of the network computing problem in which all of the source messages must be reproduced at the receiver. For network coding with a single receiver, routing is known to achieve the capacity by achieving the network min-cut upper bound. We extend the definition of min-cut to the network computing problem and show that the min-cut is still an upper bound on the maximum achievable rate and is tight for computing (using coding) any target function in multi-edge tree networks. It is also tight for computing linear target functions in any network. We also study the bound's tightness for different classes of target functions. In particular, we give a lower bound on the computing capacity in terms of the Steiner tree packing number and a different bound for symmetric functions. We also show that for certain networks and target functions, the computing capacity can be less than an arbitrarily small fraction of the min-cut bound.
Velocity measurements in a shock-separated free shear layer

Two-component laser Doppler velocimetry (LDV) measurements were made in a planar, shock-separated free shear layer formed by the convergence of two supersonic streams past a thick plate. High-speed wall pressure measurements locate the unsteady shock wave formed by this interaction and, consequently, allow separation of the effects of shock motion from the turbulence fluctuations in the velocity measurements of the shear layer. Shock-induced separation dramatically increases the normal stresses and shear stress. The shock-separated shear layer displays a positive shear stress region between separation and reattachment. Reattachment produces a shift in turbulent kinetic energy from the streamwise component to the transverse component. The region of shock motion has a relatively constant width irrespective of distance from the wall.
Asymptotic Optimality Theory for Decentralized Sequential Multihypothesis Testing Problems

The Bayesian formulation of sequentially testing M ≥ 3 hypotheses is studied in the context of a decentralized sensor network system. In such a system, local sensors observe raw observations and send quantized sensor messages to a fusion center which makes a final decision when stopping taking observations. Asymptotically optimal decentralized sequential tests are developed from a class of “two-stage” tests that allows the sensor network system to make a preliminary decision in the first stage and then optimize each local sensor quantizer accordingly in the second stage. It is shown that the optimal local quantizer at each local sensor in the second stage can be defined as a maximin quantizer which turns out to be a randomization of at most M-1 unambiguous likelihood quantizers (ULQ). We first present in detail our results for the system with a single sensor and binary sensor messages, and then extend to more general cases involving any finite alphabet sensor messages, multiple sensors, or composite hypotheses.
Public Health and Liberty: Beyond the Millian Paradigm

A fundamental question for the ethical foundations of public health concerns the moral justification for limiting or overriding individual liberty. What might justify overriding the individual moral claim to non-interference or to self-realization? This paper argues that the libertarian justification for limiting individual liberty known as the ‘harm principle’ or the ‘Millian paradigm’ is inadequate as a basis of public health ethics and policy. But simply pitting some collectivist value or utilitarian criterion over against individual liberty is not theoretically satisfactory, either. John Stuart Mill himself was not a Millian, in this sense, and his utilitarianism does not pit itself against individual liberty as a situation of balancing conflicting values. A reconsideration of Mill, particularly in light of the later work of Berlin on liberty, points toward a conception of relational liberty that is crucial for public health ethics because it contains within itself the basis for its own moral limitation.
Posted Prices and Bid Affiliation: Evidence from Experimental Auctions

In most experimental auctions, researchers ask participants to bid on the same item in multiple po- tentially binding rounds, posting the price submitted by the top bidder or bidders after each of those rounds. If bids submitted in later rounds are affiliated with posted prices from earlier rounds, this practice could result in biased value estimates. In this article, we discuss the results of an experiment designed explicitly to test whether posted prices affect bidding behavior. We find that for familiar items, high posted prices lead to increased bids in subsequent rounds. Our results have implications for researchers conducting experimental auctions. article advances the literature in several im- portant ways. First, we report the design and results of the only study designed specifically to control for the effects of posted prices on bids in subsequent rounds. We do this with the aid of confederate bidders who were instructed to bid within a certain narrow range. Thus, we have multiple treatments that vary only by the presence or absence of confederate bidders, al- lowing for what we believe to be the cleanest possible test of the effect of posted prices on bidding behavior in later rounds. While List and Shogren (1999) model bids in round t as a function of the posted price in round t−1, through our use of confederate bidders to con- trol posted prices we are able to test whether exposure to high posted prices has an effect that accumulates over the course of multiple rounds, leading to a gradual increase in mean bids. Second, our methods of analysis are more complete than previous work examining bid af- filiation. We not only compare summary statis- tics from early and late rounds, but we also use panel data analysis to understand how in- dividual participants' bids are affected by the presence of confederate bidders. Focusing on individuals rather than summary statistics al- lows us to understand how individual-specific characteristics influence affiliation, and it also allows us to better understand the role of out- liers.
A wideband, low-noise superconducting amplifier with high dynamic range

Amplifiers are ubiquitous in electronics and play a fundamental role in a wide range of scientific measurements. From a user's perspective, an ideal amplifier has very low noise, operates over a broad frequency range, and has a high dynamic range - it is capable of handling strong signals with little distortion. Unfortunately, it is difficult to obtain all of these characteristics simultaneously. For example, modern transistor amplifiers offer multi-octave bandwidths and excellent dynamic range. However, their noise remains far above the fundamental limit set by the uncertainty principle of quantum mechanics. Parametric amplifiers, which predate transistor amplifiers and are widely used in optics, exploit a nonlinear response to transfer power from a strong pump tone to a weak signal. If the nonlinearity is purely reactive, ie. nondissipative, in theory the amplifier noise can reach the quantum-mechanical limit. Indeed, microwave frequency superconducting Josephson parametric amplifiers do approach the quantum limit, but generally are narrow band and have very limited dynamic range. In this paper, we describe a superconducting parametric amplifier that overcomes these limitations. The amplifier is very simple, consisting only of a patterned metal film on a dielectric substrate, and relies on the nonlinear kinetic inductance of a superconducting transmission line. We measure gain extending over 2 GHz on either side of an 11.56 GHz pump tone, and we place an upper limit on the added noise of the amplifier of 3.4 photons at 9.4 GHz. Furthermore, the dynamic range is very large, comparable to microwave transistor amplifiers, and the concept can be applied throughout the microwave, millimeter-wave and submillimeter-wave bands.
Convex Optimization on Banach Spaces

Greedy algorithms which use only function evaluations are applied to convex optimization in a general Banach space $$X$$X. Along with algorithms that use exact evaluations, algorithms with approximate evaluations are treated. A priori upper bounds for the convergence rate of the proposed algorithms are given. These bounds depend on the smoothness of the objective function and the sparsity or compressibility (with respect to a given dictionary) of a point in $$X$$X where the minimum is attained.
Flexible Work Time in Germany: Do Workers Like It and How Have Employers Exploited It Over the Cycle?

After describing qualitatively the increasingly flexible organization of work hours in Germany, I turn to the German Socio-Economic Panel to quantify practices and trends, and assess their effects on workers and employers. Measuring flexibility as the extent to which overtime is compensated with time off, and hence receives no overtime premium, I show that hourly-paid workers have undergone a regime shift towards more flexibility since 1984, while salaried workers have maintained an already high level of flexibility. I find weak evidence that flexibility causes workers to be slightly less satisfied with their work and more satisfied with their leisure. Over the boom and bust cycle of 2005–2009, I find that for hourly-paid workers in manufacturing, paid and unpaid overtime hours were equally cyclical, but that the cycle for unpaid overtime led the cycle for paid overtime. The results suggest that while the new practices do free employers to make more cyclical adjustments in hours, they have not eliminated the need for adjustments in paid overtime. I identify as constraints ceilings on cumulated overtime hours to be compensated with time off and the window within which the compensation in time off must occur.
A Multi-Round Communication Lower Bound for Gap Hamming and Some Consequences

The Gap-Hamming-Distance problem arose in the context of proving space lower bounds for a number of key problems in the data stream model. In this problem, Alice and Bob have to decide whether the Hamming distance between their $n$-bit input strings is large (i.e., at least $n/2 + \sqrt n$) or small (i.e., at most $n/2 - \sqrt n$); they do not care if it is neither large nor small. This $\Theta(\sqrt n)$ gap in the problem specification is crucial for capturing the approximation allowed to a data stream algorithm. Thus far, for randomized communication, an $\Omega(n)$ lower bound on this problem was known only in the one-way setting. We prove an $\Omega(n)$ lower bound for randomized protocols that use any constant number of rounds. As a consequence we conclude, for instance, that $\epsilon$-approximately counting the number of distinct elements in a data stream requires $\Omega(1/\epsilon^2)$ space, even with multiple (a constant number of) passes over the input stream. This extends earlier one-pass lower bounds, answering a long-standing open question. We obtain similar results for approximating the frequency moments and for approximating the empirical entropy of a data stream. In the process, we also obtain tight $n - \Theta(\sqrt{n}\log n)$ lower and upper bounds on the one-way deterministic communication complexity of the problem. Finally, we give a simple combinatorial proof of an $\Omega(n)$ lower bound on the one-way randomized communication complexity.
Couples as partners and parents over children's early years.

We used data from the Fragile Families and Child Wellbeing Study to examine how couple relationship quality and parental engagement are linked over children’s early years—when they are infants, toddlers, and preschoolers. Our sample included 1,630 couples that were coresident over years 1 to 3 and 1,376 couples that were coresident over years 3 to 5 (1,196 over both periods). Overall, we found that better relationship quality predicted greater parental engagement for both mothers and fathers—especially in the infant to toddler years; in contrast, we found little evidence that parental engagement predicted future relationship quality. Married and cohabiting couples were generally similar in how relationship quality and parenting were linked.
Solving constrained minimum-time robot problems using the sequential gradient restoration algorithm

In this paper three constrained minimum-time control problems of a two-link manipulator are solved using the sequential gradient and restoration algorithm (SGRA). In addition to the hard bounds on the control torques commonly considered in the literature, we also consider cases with bounded output power and with a constrained shoulder arm. The inequality constraints considered are reduced via Valentine-type transformations to non-differential path equality constraints. The SGRA is then used to solve these transformed problems with equality constraints. The results obtained indicate that at least one of the two controls is at its limits at any instant in time. The remaining control then adjusts itself so that none of the system constraints is violated. Hence the minimum-time control is either a pure bang–bang control or a combined bang—bang/singular control.
Probabilistic study of cascading failures in complex interdependent lifeline systems

Abstract The internal complexity of lifeline systems and their standing interdependencies can operate in conjunction to amplify the negative effects of external disruptions. This paper introduces a simulation-based methodology to evaluate the joint impact of interdependence, component fragilities, and cascading failures in systemic fragility estimates. The proposed strategy uses a graph model of interdependent networks, an enhanced betweenness centrality for cascading failures approximation, and an interdependence model accounting for coupling uncertainty in the simulation of damage propagation for probabilistic performance assessment. This methodology is illustrated through its application to a realistic set of power and water networks subjected to earthquake scenarios and random failures. Test case results reveal two key insights: (1) the intensity of a perturbation influences interdependent systemic fragility by shaping the magnitudes of initial component damage and, sometimes counter-intuitively, the subsequent interdependence effects and (2) increasing local redundancy mitigates the effects of interdependence on systemic performance, but such intervention is incapable of eliminating interdependent effects completely. The previous insights provide basic guidelines for the design of systemic retrofitting policies. Additionally, the limitations of local capacity redundancy as a fragility control measure highlight the need for a critical assessment of intervention strategies in distributed infrastructure networks. Future work will assess the fragility-reduction efficiency of strategies involving informed manipulation of individual systemic topologies and the interdependence interfaces connecting them.
Modification of Surface States in Ultrathin Films via Hybridization with the Substrate: A Study of Ag on Ge

The Shockley surface state of Ag(111) develops unusual band dispersion relations for Ag films of decreasing thicknesses on Ge(111), as observed by angle-resolved photoemission. Its parabolic dispersion in the thick-film limit shifts toward higher binding energies and splits into multiple bands with dispersions that reflect the valence band structure of Ge including the heavy-hole, light-hole, and split-off bands. The results are explained in terms of a hybridization interaction between the Ag surface state and the Ge substrate states.
Accelerated electrical degradation of machine winding insulation

Modern electrical machines must be designed as rugged and flexible. The use of power electronic devices cause voltage spikes and introduce harmonics that electrically degrade the insulation of the windings in the machines. Power electronic driver circuits required high frequency and high operating temperatures, which affect the aging and breakdown properties of the machine winding insulation. High frequency pulse voltages can be used to study the impact of electrical degradation of the machine winding insulation that exists in electrical machines. Insulation materials were tested at 90% rated temperature for the materials. Evaluation of the change in dielectric strength was monitored versus the aging caused by the high frequency pulse voltage. In many high voltage systems, breakdown voltage is an indication of insulation condition. Partial discharge presents issues in electromagnetic compatibility as a noise source. Therefore, breakdown test and partial discharge inception/extinction voltage test at 60 Hz was performed on the twisted wire samples.
Copper(II)-Catalyzed Aminohydroxylation of Olefins

We report a novel copper(II)-catalyzed aminohydroxylation in which both heteroatoms of an N-sulfonyl oxaziridine are added across an alkene in a regioselective fashion. A variety of styrenes and electron-rich alkenes can be aminohydroxylated using this protocol. Preliminary investigations indicate that this new process is a rare non-oxenoid reaction of N-sulfonyl oxaziridines, involving a stepwise, polar mechanism rather than a concerted process.
Speckle Statistics in Adaptively Corrected Images

Imaging observations are generally affected by a fluctuating background of speckles, a particular problem when detecting faint stellar companions at small angular separations. These speckles can be created by both short-lived atmospheric aberrations and slowly changing distortions in the optical system. Over the course of a long-exposure image, the combination of many independent realizations of speckle patterns forms a halo in the point-spread function (PSF) of characteristic scale Δθ ~ λ/r0 (where r0 is the coherence length in the pupil). While adaptive optics can increase the achievable image contrast, speckle noise remains a major source of random error, which decreases the sensitivity of companion detection observations near the diffraction limit. Knowing the distribution of the speckle intensities at a given location in the image plane is therefore important for understanding the noise limits of companion detection. The speckle noise limit in a long-exposure image is characterized by the intensity variance and the speckle lifetime. In this paper we address the former quantity through the distribution function of speckle intensity. Previous theoretical work has predicted a form for this distribution function at a single location in the image plane. We developed a fast readout mode to take short exposures of stellar images corrected by adaptive optics at the ground-based UCO/Lick Observatory, with integration times of 5 ms and a time between successive frames of 14.5 ms (λ = 2.2 μm). These observations temporally oversample and spatially Nyquist sample the observed speckle patterns. We show, for various locations in the image plane, that the observed distribution of speckle intensities is consistent with the predicted form. In addition, we demonstrate a method by which Ic and Is can be mapped over the image plane. As the quantity Ic is proportional to the PSF of the telescope free of random atmospheric aberrations, this method can be used for PSF calibration and reconstruction.
Rapid determination of enantiomeric excess: a focus on optical approaches

High-throughput screening (HTS) methods are becoming increasingly essential in discovering chiral catalysts or auxiliaries for asymmetric transformations due to the advent of parallel synthesis and combinatorial chemistry. Both parallel synthesis and combinatorial chemistry can lead to the exploration of a range of structural candidates and reaction conditions as a means to obtain the highest enantiomeric excess (ee) of a desired transformation. One current bottleneck in these approaches to asymmetric reactions is the determination of ee, which has led researchers to explore a wide range of HTS techniques. To be truly high-throughput, it has been proposed that a technique that can analyse a thousand or more samples per day is needed. Many of the current approaches to this goal are based on optical methods because they allow for a rapid determination of ee due to quick data collection and their parallel analysis capabilities. In this critical review these techniques are reviewed with a discussion of their respective advantages and drawbacks, and with a contrast to chromatographic methods (180 references).
Synthesis and Structure of the Rubidium Uranium Selenophosphate Rb4U2P5Se17

Black crystals of the rubidium uranium selenophosphate Rb4U2P5Se17 have been prepared by the solid-state reaction of uranium, P2Se5, and Rb2Se3 at 1023 K. The compound crystallizes with four formula units in the triclinic space group P with cell constants at 100 K of a =10.0824(2), b = 10.6905(2), c = 15.7845(3) A, α = 84.678(1), β = 76.125(1), γ = 85.874(1)°. Its complex three-dimensional structure displays four different types of ligands that bridge uranium atoms. Three are P2Se64– anions in different bonding modes and the fourth is an asymmetric Se22– dianion. The compound may be written Rb4U2(P2Se6)2.5(Se2) and is charge-balanced as a U4+ compound.
Engineered Nanoparticles for Drug Delivery in Cancer Therapy

In medicine, nanotechnology has sparked a rapidly growing interest as it promises to solve a number of issues associated with conventional therapeutic agents, including their poor water solubility (at least, for most anticancer drugs), lack of targeting capability, nonspecific distribution, systemic toxicity, and low therapeutic index. Over the past several decades, remarkable progress has been made in the development and application of engineered nanoparticles to treat cancer more effectively. For example, therapeutic agents have been integrated with nanoparticles engineered with optimal sizes, shapes, and surface properties to increase their solubility, prolong their circulation half-life, improve their biodistribution, and reduce their immunogenicity. Nanoparticles and their payloads have also been favorably delivered into tumors by taking advantage of the pathophysiological conditions, such as the enhanced permeability and retention effect, and the spatial variations in the pH value. Additionally, targeting ligands (e.g., small organic molecules, peptides, antibodies, and nucleic acids) have been added to the surface of nanoparticles to specifically target cancerous cells through selective binding to the receptors overexpressed on their surface. Furthermore, it has been demonstrated that multiple types of therapeutic drugs and/or diagnostic agents (e.g., contrast agents) could be delivered through the same carrier to enable combination therapy with a potential to overcome multidrug resistance, and real-time readout on the treatment efficacy. It is anticipated that precisely engineered nanoparticles will emerge as the next-generation platform for cancer therapy and many other biomedical applications.
What makes a crystal supersolid

For nearly half a century the supersolid phase of matter has remained mysterious, not only eluding experimental observation, but also generating a great deal of controversy among theorists. The recent discovery of what is interpreted as a non-classical moment of inertia at low temperature in solid 4He [E. Kim and M.H.W. Chan, Nature 427 225 (2004a); E. Kim and M.H.W. Chan, Science 305 1941 (2004b); E. Kim and M.H.W. Chan, Phys. Rev. Lett. 97 115302 (2006); A.C. Clark and M.H.W. Chan, J. Low Temp. Phys. 138 853 (2005)] has elicited much excitement as a possible first observation of a supersolid phase. In the two years following the discovery, however, more puzzles than answers have been provided to the fundamental issue of whether the supersolid phase exists, in helium or any other naturally occurring condensed matter system. Presently, there is no established theoretical framework to understand the body of experimental data on 4He. Different microscopic mechanisms that have been suggested to underlie supe...