cssi/SciSciGPT-SciSciNet huggingface dataset:
Last hired, first fired? Black-white unemployment and the business cycle

Studies have tested the claim that blacks are the last hired during periods of economic growth and the first fired in recessions by examining the movement of relative unemployment rates over the business cycle. Any conclusion drawn from this type of analysis must be viewed as tentative because cyclical movements in the underlying transitions into and out of unemployment are not examined. Using Current Population Survey data matched across adjacent months from 1989–2004, this article provides the first detailed examination of labor market transitions for prime-age black and white men to test the last hired, first fired hypothesis. Considerable evidence is presented that blacks are the first fired as the business cycle weakens. However, no evidence is found that blacks are the last hired. Instead, blacks appear to be initially hired from the ranks of the unemployed early in the business cycle and later are drawn from nonparticipation. The narrowing of the racial unemployment gap near the peak of the business cycle is driven by a reduction in the rate of job loss for blacks rather than increases in hiring.
Diffusive transport enhancement by isolated resonances and distribution tails growth in hadronic beams

The escape rates and evolution of a distribution of particles are considered for a 2-D model of transverse motion of particles in hadronic storage rings, when nonlinear resonances and external diffusion are present. Dynamic enhancement of diffusion inside separatrices can develop under a certain geometry of resonance oscillations and relatively wide resonances, leading to the fast growth of distribution tails and escape rates. The phenomenon is absent in 1-D. >
Family Safety Nets and Economic Transition: A Study of Worker Households in Poland

Can Eastern European families most severely impoverished during the transition to capitalism rely on private family safety nets? This question is likely critical for the transition's success, but little is known about family networks in Eastern Europe. We analyze newly available Polish household surveys, conducted both before and after Poland's economic transition, which measure private inter-household transfers. Such transfers are large and widespread in Poland, and in many ways appear to function like means-tested public transfers. They flow from high to low-income households and are targeted to young couples, families with many children and those experiencing illness. Private transfer patterns also suggest that they are responsive to liquidity constraints. Our results from 1987 data indicate that private transfers could fill a non-trivial portion of the income gap left by unemployment. However, we also find evidence from 1992 data suggesting that family networks weakened somewhat after the transition.
A semigroup approach to wreath-product extensions of Solomon's descent algebras

There is a well-known combinatorial model, based on ordered set partitions, of the semigroup of faces of the braid arrangement. We generalize this model to obtain a semigroup ${\cal F}_n^G$ associated with $G\wr S_n$, the wreath product of the symmetric group $S_n$ with an arbitrary group $G$. Techniques of Bidigare and Brown are adapted to construct an anti-homomorphism from the $S_n$-invariant subalgebra of the semigroup algebra of ${\cal F}_n^G$ into the group algebra of $G\wr S_n$. The colored descent algebras of Mantaci and Reutenauer are obtained as homomorphic images when $G$ is abelian.
List decoding of turbo codes

List decoding of turbo codes is analyzed under the assumption of a maximum-likelihood (ML) list decoder. It is shown that large asymptotic gains can be achieved on both the additive white Gaussian noise (AWGN) and fully interleaved flat Rayleigh-fading channels. It is also shown that the relative asymptotic gains for turbo codes are larger than those for convolutional codes. Finally, a practical list decoding algorithm based on the list output Viterbi algorithm (LOVA) is proposed as an approximation to the ML list decoder. Simulation results show that the proposed algorithm provides significant gains corroborating the analytical results. The asymptotic gain manifests itself as a reduction in the bit-error rate (BER) and frame-error rate (FER) floor of turbo codes.
On estimating cosmology-dependent covariance matrices

We describe a statistical model to estimate the covariance matrix of matter tracer two-point correlation functions with cosmological simulations. Assuming a fixed number of cosmological simulation runs, we describe how to build a `statistical emulator' of the two-point function covariance over a specified range of input cosmological parameters. Because the simulation runs with different cosmological models help to constrain the form of the covariance, we predict that the cosmology-dependent covariance may be estimated with a comparable number of simulations as would be needed to estimate the covariance for fixed cosmology. Our framework is a necessary first step in planning a simulations campaign for analyzing the next generation of cosmological surveys.
Basic properties of strong mixing conditions. A survey and some open questions

This is an update of, and a supplement to, a 1986 survey paper by the author on basic properties of strong mixing conditions.
Skill distribution and income disparity in a North‐South trade model

What are the impacts of free trade agreement on the welfare of different types of workers in a developed country? What is the impact of free trade on a developed country's income disparity? What is the effect of free trade on the skill distribution of a developed country? The objective of this paper is to address the above questions in a two- sector general-equilibrium North-South trade model in which both countries produce one final good and one high-tech intermediate input. The final good is produced with the use of a high-tech intermediate input and unskilled workers. Horizontally differentiated skilled workers produce the high-tech intermediate input. Each country is populated by a continuum of unskilled workers with differential potential ability. Workers in the North and South can acquire skills by investment in training or education. Thus, skill distri- bution in the North and South is determined endogenously in the model through a self- selection process. I characterize two different types of equilibria: a closed-economy equilibrium without trade and a free trade equilibrium. Then, I investigate the impact of free trade, in the presence of training costs, on the skill distribution within each
Optimal energy allocation and admission control for communications satellites

We address the issue of optimal energy allocation and admission control for communications satellites in earth orbit. Such satellites receive requests for transmission as they orbit the earth, but may not be able to serve them all, due to energy limitations. The objective is to choose which requests to serve so that the expected total reward is maximized. The special case of a single energy-constrained satellite is considered. Rewards and demands from users for transmission (energy) are random and known only at request time. Using a dynamic programming approach, an optimal policy is derived and is characterized in terms of thresholds. Furthermore, in the special case where demand for energy is unlimited, an optimal policy is obtained in closed form. Although motivated by satellite communications, our approach is general and can be used to solve a variety of resource allocation problems in wireless communications.
Development and Validation of Risk Adjustment Models for Long-Term Mortality and Myocardial Infarction Following Percutaneous Coronary Interventions

Background—Existing models for outcome after percutaneous coronary interventions (PCIs) lack assessment of long-term prognosis. Our goal was to derive 1- and 5-year mortality and mortality/myocardial infarction (MI) risk models for PCI outcomes from simple, easily obtainable clinical and laboratory variables. Methods and Results—Using the Mayo Clinic registry, we analyzed long-term mortality and mortality/MI following PCIs on 9165 unique patients from January 1, 2001, through December 31, 2007. Cox proportional hazards regression was used to model the calculated risk score and major procedural complications. A total of 1243 patients died, and 696 had MI. Separate risk models derived from clinical, procedural, and laboratory characteristics were made for mortality and mortality/MI. Older age, comorbid conditions, low ejection fraction, acute MI, history of smoking, heart failure, hyperlipidemia, 3-vessel disease, procedural failure, ventricular arrhythmia during PCI, and low medication score were predictor...
Does the Fed Respond to Oil Price Shocks

A common view in the literature is that systematic monetary policy responses to the inflation caused by oil price shocks have been an important source of aggregate fluctuations in the US economy. Earlier empirical evidence in support of such a link was based on inappropriate econometric models. We show that there is no credible evidence that monetary policy responses to oil price shocks caused large aggregate fluctuations in the 1970s and 1980s or more recently. Our analysis suggests that the traditional monetary policy reaction framework should be replaced by models that take account of the endogeneity of the real price of oil and that allow policy responses to depend on the underlying causes of oil price shocks.
Wireless peer-to-peer mutual broadcast via sparse recovery

This paper studies a problem frequently seen in wireless networks: Every node wishes to broadcast information to nodes within a single hop, which are referred to as its peers. We call this problem mutual broadcast. A novel solution is proposed, which exploits the multiaccess nature of the wireless medium and addresses the half-duplex constraint at the fundamental level. The defining feature of the scheme is to let all nodes send their messages at the same time, where each node broadcasts a codeword (selected from its unique codebook) consisting of on-slots and off-slots, where it transmits only during its on-slots, and listens to its peers through its own off-slots. Decoding can be viewed as a problem of sparse support recovery based on linear measurements. In case each message consists of a small number of bits, an iterative message-passing algorithm based on belief propagation is developed, the performance of which is characterized using a state evolution formula in the limit where each node has a large number of peers. Numerical results demonstrate that, to achieve the same reliability for mutual broadcast, the proposed scheme achieves three to five times the rate of ALOHA and carrier-sensing multiple-access (CSMA) in typical scenarios.
Fertility and the environment in a natural resource dependent economy: Evidence from Petén, Guatemala

This paper examines potential relations between factors related to fertility and the access to and use of natural resources in Peten, Guatemala. The Peten forms the heart of the Selva Maya, the largest lowland humid forest in Mesoamerica. The rapid in-migration of subsistence maize farmers has converted much of the Peten’s forests to agricultural fields. Population dynamics have been transformed in that virtually all farm families have arrived since the 1970s and that total fertility rates exceed the national rural mean. Continued migration, exceptionally high fertility, a youthful population, and a large consumer to producer ratio are hypothesized to be related to the dramatic land cover dynamics shaping the landscape of the Peten. An emerging body of literature suggests that environmental factors can affect fertility decision-making and behaviors, especially in natural resource dependent economies like that of the Peten. This paper examines these relationships using data from the 1998/99 Demographic Health Survey in Guatemala. Data on natural resource access and utilization were collected as part of an environment module, in addition to demographic and health information. This dataset, the first ever environmental module of the Demographic Health Survey, provides a unique opportunity to examine possible relationships between fertility and the environment in a tropical agricultural frontier.
Additive damages, fat-tailed climate dynamics, and uncertain discounting

This paper in applied theory argues that there is a loose chain of reasoning connecting the following three basic links in the economics of climate change: 1) additive damages may be more appropriate for analyzing the impacts of global warming than multiplicative damages; 2) an uncertain feedback-forcing coefficient, which might be near one with infinitesimal probability, can cause the distribution of the future time trajectory of global temperatures to have fat tails and a high variance; 3) when highvariance additive damages are discounted at an uncertain rate of pure time preference, which might be near zero with infinitesimal probability, it can make expected present discounted disutility very large. Some possible implications for welfare analysis and climate-change policy are briefly noted.
The economics of faith: using an apocalyptic prophecy to elicit religious beliefs in the field

Abstract We model religious faith as a “demand for beliefs,” following the logic of the Pascalian wager. We show how standard experimental interventions linking financial consequences to falsifiable religious statements can elicit and characterize beliefs. We implemented this approach with members of a group that expected the “End of the World” to occur on May 21, 2011 by varying monetary prizes payable before and after May 21st. To our knowledge, this is the first incentivized elicitation of religious beliefs ever conducted. The results suggest that the members held extreme, sincere beliefs that were unresponsive to experimental manipulations in price.
Computer Simulation of Reconnection in Planetary Magnetospheres

The earth’s magnetosphere provides an ideal opportunity to model reconnection in well known geometries that are close enough to the idealized analytic models to make a comparison of the computer models with analytic theory meaningful. In addition more detailed, even three-dimensional, models can be used for a comparison with extended data from in situ observations. The computer studies have basically confirmed the reconnection picture that was based on two-dimensional steady state models and linear analytic theory. The three-dimensional models in particular have also added a lot more information on the reconnection process and the structure of flow, magnetic fields, and currents including many features that are consistent with observations and empirical models of geomagnetic substorms.
Why Are Proteins Charged? Networks of Charge–Charge Interactions in Proteins Measured by Charge Ladders and Capillary Electrophoresis

Almost all proteins contain charged amino acids. While the function in catalysis or binding of individual charges in the active site can often be identified, it is less clear how to assign function to charges beyond this region. Are they necessary for solubility? For reasons other than solubility? Can manipulating these charges change the properties of proteins? A combination of capillary electrophoresis (CE) and protein charge ladders makes it possible to study the roles of charged residues on the surface of proteins outside the active site. This method involves chemical modification of those residues to generate a large number of derivatives of the protein that differ in charge. CE separates those derivatives into groups with the same number of modified charged groups. By studying the influence of charge on the properties of proteins using charge ladders, it is possible to estimate the net charge and hydrodynamic radius and to infer the role of charged residues in ligand binding and protein folding.
Probabilistic projections of HIV prevalence using Bayesian melding.

The Joint United Nations Programme on HIV/AIDS (UNAIDS) has developed the Estimation and Projection Package (EPP) for making national estimates and short-term projections of HIV prevalence based on observed prevalence trends at antenatal clinics. Assessing the uncertainty about its estimates and projections is important for informed policy decision making, and we propose the use of Bayesian melding for this purpose. Prevalence data and other information about the EPP model’s input parameters are used to derive a probabilistic HIV prevalence projection, namely a probability distribution over a set of future prevalence trajectories. We relate antenatal clinic prevalence to population prevalence and account for variability between clinics using a random effects model. Predictive intervals for clinic prevalence are derived for checking the model. We discuss predictions given by the EPP model and the results of the Bayesian melding procedure for Uganda, where prevalence peaked at around 28% in 1990; the 95% prediction interval for 2010 ranges from 2% to 7%.
The symbol grounding problem

There has been much discussion recently about the scope and limits of purely symbolic models of the mind and about the proper role of connectionism in cognitive modeling. This paper describes the "symbol grounding problem": How can the semantic interpretation of a formal symbol system be made intrinsic to the system, rather than just parasitic on the meanings in our heads? How can the meanings of the meaningless symbol tokens, manipulated solely on the basis of their (arbitrary) shapes, be grounded in anything but other meaningless symbols? The problem is analogous to trying to learn Chinese from a Chinese/Chinese dictionary alone. A candidate solution is sketched: Symbolic representations must be grounded bottom-up in nonsymbolic representations of two kinds: (1) "iconic representations" , which are analogs of the proximal sensory projections of distal objects and events, and (2) "categorical representations" , which are learned and innate feature-detectors that pick out the invariant features of object and event categories from their sensory projections. Elementary symbols are the names of these object and event categories, assigned on the basis of their (nonsymbolic) categorical representations. Higher-order (3) "symbolic representations" , grounded in these elementary symbols, consist of symbol strings describing category membership relations (e.g., "An X is a Y that is Z"). Connectionism is one natural candidate for the mechanism that learns the invariant features underlying categorical representations, thereby connecting names to the proximal projections of the distal objects they stand for. In this way connectionism can be seen as a complementary component in a hybrid nonsymbolic/symbolic model of the mind, rather than a rival to purely symbolic modeling. Such a hybrid model would not have an autonomous symbolic "module," however; the symbolic functions would emerge as an intrinsically "dedicated" symbol system as a consequence of the bottom-up grounding of categories' names in their sensory representations. Symbol manipulation would be governed not just by the arbitrary shapes of the symbol tokens, but by the nonarbitrary shapes of the icons and category invariants in which they are grounded.
Wine in Your Knapsack

We pose several Knapsack Problems (KPs) to select the optimal subset of wines subject to budget and quantity constraints. The first problem seeks the subset of wines, from a single cultivar (zinfandel) that maximizes the sum of ratings subject to a budget constraint. We modify this problem by adding an equality constraint on the number of bottles that must be chosen. The third problem seeks to maximize the sum of ratings from three different cultivars (cabernet sauvignon, pinot noir, and zinfandel) subject to a budget constraint and then a budget and minimum bottle constraints for each cultivar. The rating maximization problem may have multiple solutions. We also pose two expenditure minimization problems, subject to achieving the maximum sum of ratings. We extend the model by defining an integer choice problem, that allows multiple purchases of the same wine, and by accounting for possible non-linearities between wine ratings and utilities. Applications of this model include procurement decisions for tastings, special events or building a personal wine cellar.
Numerical Validation of the Squire-Young Formula for Profile Drag Prediction

The Squire–Young formula is widely used to calculate profile drag in two-dimensional airfoil analyses. Although experience shows that the formula provides reasonable and accurate predictions, full Navier–Stokes computational fluid dynamics allows for a numerical validation of the formula. A method is presented for evaluating the Squire–Young formula from a computational fluid dynamics solution, and demonstrated for several airfoils. The agreement between profile-drag coefficients determined using the Squire–Young formula and those calculated directly from the computational fluid dynamics solution using surface integration is typically within 2–3% in the low-drag range, with error increasing at higher lift coefficients. The applicability of the underlying assumptions is discussed, and the validity of the assumed variation of shape factor and edge velocity in the wake is investigated for a symmetric airfoil at zero lift. The formula is also demonstrated as being insensitive to spurious drag that may occur d...
Synthesis and structural investigation of a new ternary transition metal nitride, Co3W3N

Abstract A new ternary transition metal nitride, Co3W3N, has been synthesized by the ammonolysis of a chemically derived metalloorganic precursor. The compound crystallizes in the η-carbide structure which is cubic in the space group Fd 3 m (227) with Z=16, as determined from powder X-ray diffraction and Rietveld refinement of the resulting diffraction pattern. The refinement converged with Rwp=0.1198, Rp=0.0725, RI=0.0400, and S=1.63. The unit cell of Co3W3N has a lattice parameter of a=11.0995(2) A. The compound is isostructural with Co3W3C, the ideal structure consisting of eight regular octahedra of tungsten atoms centred on a diamond cubic lattice and eight regular tetrahedra of cobalt atoms centred on a second diamond cubic lattice that interpenetrates the first through a 1 2 , 1 2 , 1 2 unit cell translation. Sixteen additional cobalt atoms are tetrahedrally coordinated around the cobalt tetrahedra and sixteen nitrogen atoms surround the tungsten octahedra in tetrahedral coordination.
Eclat: automatic generation and classification of test inputs

This paper describes a technique that selects, from a large set of test inputs, a small subset likely to reveal faults in the software under test. The technique takes a program or software component, plus a set of correct executions — say, from observations of the software running properly, or from an existing test suite that a user wishes to enhance. The technique first infers an operational model of the software's operation. Then, inputs whose operational pattern of execution differs from the model in specific ways are suggestive of faults. These inputs are further reduced by selecting only one input per operational pattern. The result is a small portion of the original inputs, deemed by the technique as most likely to reveal faults. Thus, the technique can also be seen as an error-detection technique. The paper describes two additional techniques that complement test input selection. One is a technique for automatically producing an oracle (a set of assertions) for a test input from the operational model, thus transforming the test input into a test case. The other is a classification-guided test input generation technique that also makes use of operational models and patterns. When generating inputs, it filters out code sequences that are unlikely to contribute to legal inputs, improving the efficiency of its search for fault-revealing inputs. We have implemented these techniques in the Eclat tool, which generates unit tests for Java classes. Eclat's input is a set of classes to test and an example program execution—say, a passing test suite. Eclat's output is a set of JUnit test cases, each containing a potentially fault-revealing input and a set of assertions at least one of which fails. In our experiments, Eclat successfully generated inputs that exposed fault-revealing behavior; we have used Eclat to reveal real errors in programs. The inputs it selects as fault-revealing are an order of magnitude as likely to reveal a fault as all generated inputs.
The MIDAS Touch: Mixed Data Sampling Regression Models

We introduce Mixed Data Sampling (henceforth MIDAS) regression models. The regressions involve time series data sampled at dieren t frequencies. Technically speaking MIDAS models specify conditional expectations as a distributed lag of regressors recorded at some higher sampling frequencies. We examine the asymptotic properties of MIDAS regression estimation and compare it with traditional distributed lag models. MIDAS regressions have wide applicability in macroeconomics and nance.
Oil Price Shocks, Monetary Policy and Stagflation

One of the central questions in recent macroeconomic history is to what extent monetary policy as opposed to oil price shocks contributed to the stagflation of the 1970s. Understanding what went wrong in the 1970s is the key to learning from the past. One explanation explored in Barsky and Kilian (2002) is that worldwide shifts in monetary policy regimes not related to the oil market played a major role in causing both the major oil price increases of the 1970s and stagflation in many economies. A competing view exemplified by Bernanke, Gertler and Watson (1997) is that the oil price shocks of the 1970s and 1980s arose exogenously with respect to global macroeconomic conditions, but were propagated by the reaction of monetary policy makers, causing stagflation in the process. This paper reviews the evidence for these two main explanations, interprets recent events in light of this evidence, and outlines implications for monetary policy.
Transfection of c6 glioma cells with the bax gene and increased sensitivity to treatment with cytosine arabinoside

OBJECT Genes known to be involved in the regulation of apoptosis include members of the bcl-2 gene family, such as inhibitors of apoptosis (bcl-2 and bcl-xl) and promoters of apoptosis (bax). The authors investigated a potential approach for the treatment of malignant gliomas by using a gene transfection technique to manipulate the level of an intracellular protein involved in the control of apoptosis. METHODS The authors transfected the murine bax gene, which had been cloned into a mammalian expression vector, into the C6 rat glioma cell line. Overexpression of the bax gene resulted in a decreased growth rate (average doubling time of 32.96 hours compared with 22.49 hours for untransfected C6, and 23.11 hours for clones transfected with pcDNA3 only), which may be caused, in part, by an increased rate of spontaneous apoptosis (0.77 +/- 0.15% compared with 0.42 +/- 0.08% for the vector-only transfected C6 cell line; p = 0.038, two-tailed Student's t-test). Treatment with 1 microM cytosine arabinoside (ara-C) resulted in significantly more cells undergoing apoptosis in the cell line overexpressing bax than in the vector-only control cell line (23.57 +/- 2.6% compared with 5.3 +/- 0.7% terminal deoxynucleotidyl transferase-mediated biotinylated-deoxyuridine triphosphate nick-end labeling technique-positive cells; p = 0.007). Furthermore, measurements of growth curves obtained immediately after treatment with 0.5 microM ara-C demonstrated a prolonged growth arrest of at least 6 days in the cell line overexpressing bax. CONCLUSIONS These results can be used collectively to argue that overexpression of bax results in increased sensitivity of C6 cells to ara-C and that increasing bax expression may be a useful strategy, in general, for increasing the sensitivity of gliomas to antineoplastic treatments.
Evaluation and Time-Scaling of Trajectories for Wheeled Mobile Robots

We present a method for evaluating the feasibility of trajectories generated by path-planing systems for wheeled mobile robots (WMRs). Constraints that limit the class of executable trajectories for a given WMR are classified as path constraints, kinematic constraints, and dynamic constraints. Path constraints, which are limits on the path geometry, are a function of the wheelbase configuration and steering mechanism. Limits that involve only functions of velocities and accelerations are termed kinematic constraints. Dynamic constraints refer to limits on force/torque inputs and frictional force constraints which must be satisfied for a trajectory to be feasible. We show that when path constraints are violated the path must be modified to achieve feasibility, while violations of kinematic and dynamic constraints can be eliminated by time scaling so that the same path is followed at a slower speed. The concepts are developed and illustrated in the context of a model for the dynamics of a conventionally steered vehicle.
Validation results of specifications for motion control interoperability

The National Institute of Standards and Technology (NIST) is participating in the Department of Energy Technologies Enabling Agile Manufacturing (TEAM) program to establish interface standards for machine tool, robot, and coordinate measuring machine controllers. At NIST, the focus is to validate potential application programming interfaces (APIs) that make it possible to exchange machine controller components with a minimal impact on the rest of the system. This validation is taking place in the enhanced machine controller (EMC) consortium and is in cooperation with users and vendors of motion control equipment. An area of interest is motion control, including closed-loop control of individual axes and coordinated path planning. Initial tests of the motion control APIs are complete. The APIs were implemented on two commercial motion control boards that run on two different machine tools. The results for a baseline set of APIs look promising, but several issues were raised. These include resolving differing approaches in how motions are programmed and defining a standard measurement of performance for motion control. This paper starts with a summary of the process used in developing a set of specifications for motion control interoperability. Next, the EMC architecture and its classification of motion control APIs into two classes, Servo Control and Trajectory Planning, are reviewed. Selected APIs are presented to explain the basic functionality and some of the major issues involved in porting the APIs to other motion controllers. The paper concludes with a summary of the main issues and ways to continue the standards process.
A Shortcut to LAD Estimator Asymptotics

Using generalized functions of random variables and generalized Taylor series expansions, we provide quick demonstrations of the asymptotic theory for the LAD estimator in a regression model setting. The approach is justified by the smoothing that is delivered in the limit by the asymptotics, whereby the generalized functions are forced to appear as linear functionals wherein they become real valued. Models with fixed and random regressors, and autoregressions with infinite variance errors are studied. Some new analytic results are obtained including an asymptotic expansion of the distribution of the LAD estimator.
HOW FAST CAN A BLACK HOLE RELEASE ITS INFORMATION

When a shell collapses through its horizon, semiclassical physics suggests that information cannot escape from this horizon. One might hope that nonperturbative quantum gravity effects will change this situation and avoid the information paradox. We note that string theory has provided a set of states over which the wave function of the shell can spread, and that the number of these states is large enough that such a spreading would significantly modify the classically expected evolution. In this article we perform a simple estimate of the spreading time, showing that it is much shorter than the Hawking evaporation time for the hole. Thus information can emerge from the hole through the relaxation of the shell state into a linear combination of fuzzballs.
Integrating cavity quantum electrodynamics and ultracold-atom chips with on-chip dielectric mirrors and temperature stabilization

We have fabricated an atom chip device which combines the circuitry for magnetic trapping of cold atoms with high-finesse optical resonators suitable for cavity QED in the single-atom strong coupling regime. Fabry–Perot optical resonators with finesse \(\mathcal{F}\ge2\times10^5\) were formed between a micropatterned on-chip planar mirror with lateral dimension of ≤ 100 μm and a curved mirror suspended above the chip. The strong and rapid thermal coupling between on-chip electrical and optical elements was utilized to stabilize the cavity mirror separation with servo bandwidth exceeding 100 kHz during simulated operation of the atom chip.
Analytic and experimentally derived estimates of market power in deregulated electricity systems: policy implications for the management and institutional evolution of the industry

Abstract Previous experimental and game-theoretic analyses of deregulated electricity markets suggest that communities having four or less effective suppliers, either because of transmission constraints or load characteristics, or retail customers facing suppliers or marketing agents having more than 70% of the region's market, are likely to experience prices well above competitive levels. While state regulatory bodies may be able to forestall the onset of retail wheeling and non-regulated retail energy pricing until a single supplier does not dominate initial market shares, it is more difficult to mute the exercise of market power by generators serving electrically isolated load pockets. In both instances, if the accrual of some excess profits by initial, non-regulated suppliers are not tolerated, then little incentive will have been provided for competitors to enter the market and for more efficient technologies to evolve. Estimates are provided in this analysis of the circumstances for and the extent and duration of the exercise of market power. When combined with the present absence of incentives to build transmission lines that would reduce bottlenecks and the existing utilities' insistence upon full recovery of stranded costs through line charges and access fees, the powerful incentives to develop distributed generation are highlighted.
Rolling closed string tachyons and the big crunch

We study the low-energy effective field equations that couple gravity, the dilaton, and the bulk closed string tachyon of bosonic closed string theory. We establish that whenever the tachyon induces the rolling process, the string metric remains fixed while the dilaton rolls to strong coupling. For negative definite potentials we show that this results in an Einstein metric that crunches the universe in finite time. This behavior is shown to be rather generic even if the potentials are not negative definite. The solutions are reminiscent of those in the collapse stage of a cyclic universe cosmology where scalar field potentials with negative energies play a central role.
A constrained asymmetry LMS algorithm for PRML disk drive read channels

We present an implementation of a constrained least mean square (C-LMS) algorithm with application to high-speed magnetic disk drive read channels. The main advantage offered by the presented C-LMS algorithm is improved stability of the outer timing recovery loop while the spectral shaping of read-back data is performed in the inner adaptation loop. This eliminates any unstable behavior of the timing recovery loop during C-LMS algorithm adaptation. Another benefit derived from this approach is reduction in coefficient switching gradient noise. The proposed algorithm has been implemented and fabricated in a commercial read channel using a 0.18 /spl mu/m L-effective CMOS technology. It operates at 550 MHz worst case.
Analysis of a four-level DC/DC buck converter

In this paper, a four-level DC/DC buck power converter is introduced. The primary application for this converter is to regulate the center capacitor voltage in a four-level inverter system. The steady-state and average-value models for the proposed converter are developed and compared in simulation. The converter was constructed in the laboratory and verified on a four-level motor drive system. It was shown that the four-level DC/DC converter provides capacitor voltage balancing and allows higher output voltage utilization from the inverter.
Library collaboration with large digital humanities projects

The sustainability of digital humanities research projects is a pressing issue for humanities computing. Currently, even well-established large digital projects like the Linguistic Atlas Project (LAP) are at future risk because funding and other resources are contingent on grant funding or faculty status of the director, neither of which will necessarily be available to maintain the project over time. The mission of the university library, however, includes archiving and dissemination, now increasingly of digital materials as well as traditional paper. Collaboration with the university library is the only realistic option for long-term sustainability of digital humanities projects in the current environment. Unlike paper collections, which only require secure storage, digital projects also require the means of adaptation to new electronic media and operating environments. Even data storage requires that materials from digital projects be included in library media refresh cycles, which will include transfer of old data to new media as technology develops. Projects like LAP should provide resources to assist the library in starting the project archive, including staff time, and funding for equipment. Project metadata must be provided and, to the extent possible, integrated with library systems and finding aids. Project staff will also need to maintain a Web presence and tools developed for the project. Such cooperation leads toward the development of a digital institutional repository, in which research results and tools may be maintained in the library, not just for the humanities but across many disciplines.
The UT austin villa 2003 champion simulator coach: a machine learning approach

The UT Austin Villa 2003 simulated online soccer coach was a first time entry in the RoboCup Coach Competition. In developing the coach, the main research focus was placed on treating advice-giving as a machine learning problem. Competing against a field of mostly hand-coded coaches, the UT Austin Villa coach earned first place in the competition. In this paper, we present the multi-faceted learning strategy that our coach used and examine which aspects contributed most to the coach's success.
Hydrothermal synthesis and crystal structure of two new hydrated alkaline earth metal borates Sr3B6O11(OH)2 and Ba3B6O11(OH)2.

Two new hydrated borates Sr(3)B(6)O(11)(OH)(2) (1) and Ba(3)B(6)O(11)(OH)(2) (2) were hydrothermally synthesized. Their structures were determined by single-crystal X-ray diffraction and further characterized by IR, powder XRD, and DSC/TGA. Compound 1 crystallizes in the triclinic space group P-1 with unit cell parameters of a = 6.6275(13) A, b = 6.6706(13) A, c = 11.393(2) A, α = 91.06(3)°, β = 94.50(3)°, and γ = 93.12(3)°, while compound 2 crystallizes in the noncentrosymmetric monoclinic space group Pc with a = 6.958(14) A, b = 7.024(14) A, c = 11.346(2) A, and β = 90.10(3)°. In spite of the differences in symmetry and packing of the borate chains, both structures consist of the same fundamental building block (FBB) of a [B(6)O(11)(OH)(2)](-6) unit and three unique alkaline earth metal atoms.
Optimal Allocation Of Heterogeneous Robots In World Wide Web Search Engines

It is a conflicting requirement to reduce network traffic and loads on Web servers caused by the robots in a World Wide Web search engine and to increase the currency of the database in the search engine. This paper addresses the problem of finding optimal allocations of a given number of robots in a search engine to heterogeneous Internet domains such that a cost function which characterizes the combined consideration of network/server loads and database currency can be minimized. The cost function and the optimization problem are formulated based on a queueing model of search engines. Our algorithm to solve the problem uses the depth-first search strategy to traverse an enumeration tree which generates all possible allocations.
Spectra and temperature of propellant flames during depressurization

Composite propellant flame temperature and emission spectra during depressurization by rarefaction waves, using rapid scanning spectrometer
Monoamine oxidase drugs and diet

Summary Aims: To review the literature on monoamine oxidase drugs and propose a simple diet sheet. Methods: A literature search, using a range of computer data bases and the assistance of the Mental Health Group of the British Dietetic Association. Results: MAO-B drugs (e.g. Selegiline) do not require dietary restrictions. MAO-A drugs and MAOI drugs do require a restriction of the intake of tyramine. The manufacturer (Roche) of Manerix (moclobemide), an MAO-A drug, states that not more than 50 g of cheese should be eaten when taking that medication. MAOI drugs (e.g. Isocarboxazid (Cambridge), Nardil (P-D), Parnate (SK & F)) require further dietary restrictions. Patients taking MAOI drugs should not consume more than 6 mg tyramine in a single dose (i.e. a meal or snack). Conclusion: A simple diet sheet, for use with MAOI drugs, has been devised. It lists the foods which must be avoided, those which may be taken in moderation and those which may be eaten freely.
Laboratory Simulations of Abiotic Hydrocarbon Formation in Earth’s Deep Subsurface

In recent years, methane and other light hydrocarbons with an apparently abiotic origin have been identified in an increasing number of geologic fluids on Earth. These compounds have been found in a variety of geologic settings, including seafloor hydrothermal systems, fracture networks in crystalline rocks from continental and oceanic crust, volcanic gases, and gas seeps from serpentinized rocks (e.g., Abrajano et al. 1990; Kelley 1996; Sherwood Lollar 2002, 2008; Fiebig et al. 2007, 2009; Proskurowski et al. 2008; Taran et al. 2010b). Understanding the origin of these compounds has significant implications for range of topics that includes the global carbon cycle, the distribution of life in the deep subsurface (Gold 1992), and the origin of life (Martin et al. 2008). There are even claims that abiotic sources are major contributors to global hydrocarbon reservoirs (Gold 1993; Glasby 2006; Kutcherov and Krayushkin 2010; Sephton and Hazen 2013). While most experts are highly skeptical of such broad claims, it seems possible that at least some petroleum and gas reservoirs could contain hydrocarbons with an abiotic origin. Conceptually, there are two potential major sources of abiotic hydrocarbons to fluids in Earth’s crust. First, abiotic hydrocarbons could migrate to the crust from deeper sources within Earth, through processes such as convective transport, grain boundary diffusion, or release of magmatic volatiles. Second, abiotic hydrocarbons could form in situ within the crust through reduction of inorganic carbon sources. Potential substrates for carbon reduction include CO2 and CO in circulating fluids, and carbon-bearing solids such as carbonate minerals and graphite. In either case, the ultimate source of the inorganic carbon may be primordial (i.e., from the mantle) or recycled from Earth’s surface. This paper summarizes some of the recent laboratory experimental studies conducted to investigate potential …
GLSMs for non-Kahler Geometries

We identify a simple mechanism by which H-flux satisfying the modified Bianchi identity arises in garden-variety (0,2) gauged linear sigma models. Taking suitable limits leads to effective gauged linear sigma models with Green-Schwarz anomaly cancellation. We test the quantumconsistency of a class of such effective theories by constructing an off-shell superconformal algebra, identifying unexpected topological constraints on the existence of this algebra and providing evidence that these models run to good CFTs in the deep IR when all of the constraints are satisfied.
The Theory of Local Public Goods Twenty-Five Years After Tiebout: A Perspective

This paper asks, under what conditions can the Fundamental Theorem of Welfare Economics be extended to economies with local public goods? We show that there are some fairly restrictive sets of assumptions under which a competitive local public goods equilibrium (if it exists) is efficient; more generally, however, competitive local public goods equilibria may be inefficient in the allocation of individuals among communities, in the number of communities, and in the level and kinds of public goods provided. The primary sources of inefficiency are identified and analyzed; these "market" failures are closely related to some important policy issues concerning, for instance, urban concentralization, fiscal decentralization, and regional redistribution. In communities in which landlords control the public sector, the level and kinds of public goods provided may be incorrect, and what goods are provided are supplied inefficiently. In contrast, in communities in which renters control the public sector, there are no incentives for efficiency in the supply of public goods. Because of what we refer to as rental capitalization, there may in fact be perverse incentives with respect to the kinds of public goods or "bads" provided. Not only is it the case that not every competitive equilibrium is Pareto optimal, but not every Pareto efficient allocation can be sustained by a competitive local public goods equilibrium (with the appropriate lump sum redistributions) . Just as the Fundamental Theorem of Welfare Economics does not adequately reflect the vices and virtues of competition in the market economy with purely private goods, so too here: the virtues of a decentralized mechanism for providing public goods may be vastly underestimated by our analysis.
Wealth Inequality and Altruistic Bequests

This paper examines the role of bequests and inter vivos gifts in the U.S. economy, considering their importance in determining (i) the economy’s aggregate capital stock, (ii) the distribution of private net worth, and (iii) public policy outcomes and options. It focuses on several recent calibrated simulations.(This abstract was borrowed from another version of this item.)
Gauge fixing and the gibbs phenomenon

Abstract We address the question of why global gauge fixing, specifically to the lattice Landau gauge, becomes an extremely lengthy process for large lattices. We construct an artificial “gauge-fixing” problem which has the essential features encountered in actuality. In the limit in which the size of the system to be gauge fixed becomes infinite, the problem becomes equivalent to finding a series expansion in functions which are related to the Jacobi polynomials. The series converges slowly, as expected. It also converges non-uniformly, which is an observed characteristic of gauge fixing. In the limiting example, the non-uniformity arises through the Gibbs phenomenon.
Juan J. Linz: Presidencialismo y democracia. Una revisión crítica.

Este articulo revisa y evalua criticamente los argumentos de Linz acerca de los riesgos del presidencialismo. Se coincide en gran medida con Linz en que el presidencialismo tal como se ejerce de modo general resulta menos adecuado que el parlamentarismo para sostener gobiernos democraticos. Sin embargo, se cuestiona aqui varios aspectos de su argumento.