cssi/SciSciGPT-SciSciNet huggingface dataset:
Cross-covariance modelling via DAGs with hidden variables

DAG models with hidden variables present many difficulties that are absent when all nodes are observed. In particular, fully observed DAG models are identified and correspond to well-defined sets of distributions, whereas this is not true if nodes are unobserved. In this paper we characterize exactly the set of distributions given by a class of Gaussian models with one-dimensional latent variables. These models relate two blocks of observed variables, modeling only the crosscovariance matrix. We describe the relation of this model to the singular value decomposition of the cross-covariance matrix. We show that, although the model is underidentified, useful information may be extracted. We further consider an alternative parameterization in which one latent variable is associated with each block. Our analysis leads to some novel covariance equivalence results for Gaussian hidden variable models.
WHITHER GERMANY AND THE EMU IN A CHALLENGING ENVIRONMENT

While the German economy may currently be a bright spot in Europe, it has faced substantial challenges in recent years. Moreover, tensions are rising regarding Germany's responsibilities and opportunities as a member of the European Monetary Union. Other studies have documented the difficulties that Germany has encountered as a result of the unification and further integration of Europe. This paper adds to that literature by using an aggregate translog cost function approach to examine the relationships among inputs of domestic capital and labour and imports. Our findings indicate that the input pairs of capital-labour and labour-imports are substitutes. The substitutes relationship between labour and imports, which has become stronger over time, suggests that increasing globalisation will add to Germany's unemployment woes. Capital and imports appear to be weak complements, but that relationship is not statistically significant. The results also suggest that imports are playing an increasingly important role in Germany's aggregate production, accentuating the role of the international environment.
Cosmological-model-parameter determination from satellite-acquired type Ia and IIP Supernova Data

We examine the constraints that satellite-acquired Type Ia and IIP supernova apparent magnitude versus redshift data will place on cosmological model parameters in models with and without a constant or time-variable cosmological constant lambda. High-quality data which could be acquired in the near future will result in tight constraints on these parameters. For example, if all other parameters of a spatially-flat model with a constant lambda are known, the supernova data should constrain the non-relativistic matter density parameter omega to better than 1 (2, 0.5) at 1 sigma with neutral (worst case, best case) assumptions about data quality.
Diseases with rooted staggered quarks

Calculations using staggered quarks augmented with a root of the fermion determinant to reduce doubling give a qualitatively incorrect behavior in the small quark mass region. Attempts to circumvent this problem for the continuum limit involve an unproven combination of unphysical states, a loss of unitarity, and a rather peculiar non-commu tation of limits.
Design and development of a high-power LED-pumped Ce:Nd:YAG laser

Our quasi-continuous wave Ce:Nd:YAG solid-state laser was directly pumped by LED arrays, yielding a maximum of 8mJ/pulse. Comparison of pumping at 460nm and 810nm allows analysis of the performance and potential of this laser system.
Using Regular Expressions for Data Management in Stata

Regular expressions make a number of data management operations involving string variables much easier. They do this by allowing the user to search for (and copy or replace) complex patterns of characters within a string. Examples of when regular expression are useful include extracting zip codes from addresses, reformatting dates if they were entered in an inconsistent manner, and removing excess spaces from string expressions. This presentation will give the user a basic introduction to the use of regular expressions, and the Stata functions related to regular expressions, as well as examples of applications where regular expressions can be used to streamline data management.
Community issues and the bioeconomy transition: moving independence from imported oil and climate change up the local policy agenda

There are many issues and some myths that are drivers of change in this transition. World hunger, biotechnology, food versus fuel, and indirect land use; organic, natural, local foods, obesity, nutrition, and food safety; housing, healthcare, credit institutions, and economic recovery; and others are among the issues being discussed. This working paper focuses on two of the key drivers that underlie much of the discussion at this conference and they are not likely to disappear from the agenda anytime soon. A framework for local policy decisions is developed for each issue using the alternatives and consequences approach.
I Am a Better Driver Than You Think: Examining Self-Enhancement for Driving Ability.

We examined whether people recognized that others might disagree with their high self-assessments of driving ability, and, if so, why. Participants in four experiments expressed a belief that others would assess them as worse drivers than they assessed themselves. This difference appears to be caused by participants’ use of their own, idiosyncratic definition of driving ability. In Experiments 2 and 3 participants reported that others would supply similar assessments of their ability when the skill was less ambiguous. Results of Experiment 4 indicate that participants recognize that there may be more than one way to view driving performance. Participants appear aware that others likely disagree with their self-assessment of driving ability due to differences in how others define driving ability.
Rent Control with Matching Economies: A Model of European Housing Market Regulation

Housing markets are thin, and consumer search for housing is costly, time consuming, and risky. Mismatches between tenants and dwellings are common in a laissez-faire market. There are scale economies in accumulating tenants and houses and then matching them up to improve welfare. In many European countries, some housing is rent controlled and rationed by public centralized matching. Waiting time, risk in rationing, and risk in matching are costs that arise from such regulation. We show that welfare improvements over laissez-faire occur if gains from centralized matching can offset the decrease in housing quality, the possible increase in waiting times, and the risks in rationing induced by rent controls. Under regulation, there is a welfare maximizing partition of the stock into free and controlled markets; and contrary to observed practice, it is often welfare improving to set controlled rents above (not below) laissez-faire, which increases the supply offered for centralized matching and the opportunity for a better match.
Pseudorandomness and Fourier Growth Bounds for Width-3 Branching Programs

We present an explicit pseudorandom generator for oblivious, read-once, width-3 branching programs, which can read their input bits in any order. The generator has seed length ˜ O(log 3 n). The previously best known seed length for this model is n 1/2+o(1) due to Impagliazzo, Meka, and Zuckerman (FOCS ’12). Our work generalizes a recent result of Reingold, Steinke, and Vadhan (RANDOM ’13) for permutation branching programs. The main technical novelty underlying our generator is a new bound on the Fourier growth of width-3, oblivious, read-once branching programs. Specifically, we show that for any f :{0, 1} n !{0, 1} computed by such a branching program, and k2 [n], X s [n]:|s|=k b f[s] n 2 · (O(logn)) k ,
Replication strategies for highly available peer-to-peer storage

In the past few years, peer-to-peer networks have become an extremely popular mechanism for large-scale content sharing. Unlike traditional client-server applications, which centralize the management of data in a few highly reliable servers, peer-to-peer systems distribute the burden of data storage, computation, communications and administration among thousands of individual client workstations. While the popularity of this approach, exemplified by systems such as Gnutella [28.3], was driven by the popularity of unrestricted music distribution, newer work has expanded the potential application base to generalized distributed file systems [28.1], [28.4], persistent anonymous publishing [28.5], as well as support for high-quality video distribution [28.2]. The wide-spread attraction of the peer-to-peer model arises primarily from its potential for both low-cost scalability and enhanced availability. Ideally a peer-to-peer system could efficiently multiplex the resources and connectivity of its workstations across all of its users while at the same time protecting its users from transient or persistent failures in a subset of its components.
America's Forgotten Pandemic: The Influenza of 1918

Part I. An Abrupt Introduction to Spanish Influenza: 1. The great shadow Part II. Spanish Influenza: The First Wave - Spring and Summer, 1918: 2. The advance of the influenza virus 3. Three explosions - Africa, Europe, and America Part III. The Second and Third Waves: 4. The United States begins to take note 5. Spanish Influenza sweeps the country 6. Flu in Philadelphia 7. Flu in San Francisco 8. Flu at sea on voyage to France 9. Flu and the American expeditionary force 10. Flu and the Paris Peace Conference Part IV. Measurements, Research, Conclusions, and Confusions: 11. Statistics, definitions, and speculations 12. Samoa and Alaska 13. Research, frustration, and the isolation of the virus 14. Where did the flu of 1918 go? Part V. Afterword: 15. An inquiry in the peculiarities of human memory.
Understanding the Long-Run Decline in Interstate Migration

We analyze the secular decline in gross interstate migration in the United States from 1991 to 2011. We argue that migration fell because of a decline in the geographic specificity of returns to occupations, together with an increase in workers' ability to learn about other locations before moving. Micro data on earnings and occupations across space provide evidence for lower geographic specificity. Other explanations do not fit the data. A calibrated model formalizes the geographic specificity and information mechanisms and is consistent with cross-sectional and time-series evidence. Our mechanisms can explain at least half of the decline in migration.
Construction, corruption, and developing countries

The construction industry accounts for about one-third of gross capital formation. Governments have major roles as clients, regulators, and owners of construction companies. The industry is consistently ranked as one of the most corrupt: large payments to gain or alter contracts and circumvent regulations are common. The impact of corruption goes beyond bribe payments to poor quality construction of infrastructure with low economic returns alongside low funding for maintenance-and this is where the major impact of corruption is felt. Regulation of the sector is necessary, but simplicity, transparency, enforcement, and a focus on the outcomes of poor construction are likely to have a larger impact than voluminous but poorly enforced regulation of the construction process. Where government is the client, attempts to counter corruption need to begin at the level of planning and budgeting. Output-based and community-driven approaches show some promise as tools to reduce corruption. At the same time they will need to be complimented by a range of other interventions including publication of procurement documents, independent and community oversight, physical audit, and public-private anticorruption partnerships.
Up in Smoke?: Tobacco Production’s Effect on Childhood Stunting in Malawi

Growing attention on the developing world’s potential for export led growth has naturally flowed into the agricultural sector. I examine the effects of Malawian crop adoption on childhood health to determine the effects of transitioning to cash crops in risky food markets. Preliminary results indicate that cash crop households had higher levels of childhood stunting, which may suggest providing additional support for food crop production.
The design and fabrication of a Stirling engine heat exchanger module with an integral heat pipe

The conceptual design of a free-piston Stirling Space Engine (SSE) intended for space power applications has been generated. The engine was designed to produce 25 kW of electric power with heat supplied by a nuclear reactor. A novel heat exchanger module was designed to reduce the number of critical joints in the heat exchanger assembly while also incorporating a heat pipe as the link between the engine and the heat source. Two inexpensive verification tests are proposed. The SSE heat exchanger module is described and the operating conditions for the module are outlined. The design process of the heat exchanger modules, including the sodium heat pipe, is briefly described. Similarities between the proposed SSE heat exchanger modules and the LeRC test modules for two test engines are presented. The benefits and weaknesses of using a sodium heat pipe to transport heat to a Stirling engine are discussed. Similarly, the problems encountered when using a true heat pipe, as opposed to a more simple reflux boiler, are described. The instruments incorporated into the modules and the test program are also outlined.
LEAP: a learning apprentice for VLSI design

Abstract It is by now well recognized that a major impediment to developing knowledge-based systems is the knowledge-acquisition bottleneck: The task of building up a complete enough and correct enough knowledge base to provide high-level performance. This chapter proposes a new class of knowledge-based systems designed to address this knowledge-acquisition bottleneck by incorporating a learning component to acquire new knowledge through experience. In particular, we define learning apprentice systems as the class of interactive, knowledge-based consultants that directly assimilate new knowledge by observing and analyzing the problem-solving steps contributed by their users through their normal use of the system. This chapter describes a specific learning apprentice system, called LEAP, which is currently being developed in the domain of VLSI design. We also discuss design issues for learning apprentice systems more generally, as well as restrictions on the generality of our current approach.
Gene expression profiles of normal human lung cells affected by adenoviral E1B

2993 Adenoviruses with deletion of E1B gene can selectively replicate in cancer cells. The underlying mechanisms in tumor selective replication of E1B-deleted adenoviruses are insufficiently understood. Identifying genes with altered expression patterns caused by the E1B proteins in virus-infected cells will further increase our understanding of E1B functions and provide insight into the tumor-selective replication of E1B-mutated adenoviruses on the molecular level. An approach based on large-scale gene array was applied to analyze molecular changes affected by viral E1B. We identified a total of 345 genes with expression changes of two-fold or greater affected by wild-type adenovirus compared with its E1B-deleted counterpart. E1B proteins affect the expression of a diverse range of genes, including CDC25A and cyclin E involved in cell cycle regulation, BCL-2 in apoptosis, heat shock 70K protein in stress responses, and vascular endothelial growth factor in angiogenesis and transcription. These results were confirmed by quantitative real-time PCR and Western blot. This is the first study of the global profile of gene expression altered by the virus E1B in human lung cells, and the majority of the genes were previously not known to be affected by the E1B proteins. The data presented in this study will lead to more detailed analysis of E1B functions and may also lead to development of new agents and approaches for oncolytic therapy.
Scalable Formal Machine Models

In the past few years, we have seen machine-checked proofs of relatively large software systems, including compilers and micro-kernels. But like all formal arguments, the assurance gained by these mechanical proofs is only as good as the models we construct of the underlying machine. I will argue that how we construct and validate these models is of vital importance for the research community. In particular, I propose that we develop domain-specific languages (DSLs) for describing the semantics of machines, and build interpretations of these DSLs in our respective proof-development systems. This will allow us to factor out and re-use machine semantics for everything from software to hardware.
Evaluation of Skylab data for land use mapping

Skylab multispectral scanner data, digitized Skylab color IR photography, digitized Skylab black and white multiband photography, and Earth Resources Technology Satellite (ERTS) multispectral scanner data collected within a twenty-four hour time period over an area in south-central Indiana near Bloomington on June 9 and 10, 1973, were compared in a machine-aided land use analysis of the area. The overall classification performance results, obtained with nine land use classes were 87% correct classification using the 'best' 4 channels of the Skylab multispectral scanner, 80% for the channels on the Skylab multispectra scanner, which are spectrally comparable to the ERTS multispectral scanner, 88% for the ERTS multispectral scanner, 83% for the digitized color IR photography, and 76% for the digitized black and white multiband photography. The results indicate that the Skylab multispectral scanner may yield even higher classification accuracies when a noise filtered multispectral scanner data set becomes available in the near future.
A Spectropolarimetric Atlas of 61 Bright Northern Be Stars

We are developing an atlas of spectropolarimetric observations of 61 bright northern Be stars obtained from 1989-94 using the halfwave polarimeter (HPOL) at the 0.9m telescope of the University of Wisconsin Pine Bluff Observatory (PBO). The data cover the wavelength range from about 3400-7600A, with a spectral resolution of about 25A. This atlas will contain all data (297 observations total) obtained as part of a survey program with HPOL during the time when the detector in use was a dual Reticon array; the survey observations with HPOL continue, using a new CCD detector which extends the spectral coverage out to 1.05 μ m and improves the spectral resolution to about 12A. The CCD observations will be presented later in a second volume of the atlas. Only a brief summary of the findings of the survey from the first 5 years of the project is presented here. A full analysis of the data will be included in a paper to be published elsewhere. The general wavelength dependence of polarization for classical Be stars can be considered on the basis of these observations, and results on polarimetric variability are available. In particular, we find that 56% (20 of 36) of the Be stars observed 3 or more times from 1989-94 show significantly variable polarization at the level of 0.1% changes (inclusion of preliminary results from the continuing CCD survey indicates that the percentage is even higher). The timescales for these changes range from as short as night-to-night to as long as several months. Several of the stars showed evidence for polarimetric “outbursts” during the time period covered by the observations.
Nonlinear physical optics with transversely patterned quasi-phase-matching gratings

Summary from only given. Transverse patterning of periodic gratings for quasi-phase- matching (QPM) has been used to increase the tuning range of devices (through fanned gratings), to shape the amplitude profile of an interacting beam, and to create two-dimensional periodic QPM structures (nonlinear photonic crystals) for efficient noncollinear mixing.
Outstanding questions in dwarf galaxy research

Resolved observations of nearby galaxies help us to understand the evolution of dwarf galaxies. The star formation histories recovered from their fossil records place strong constraints on how dwarf galaxies have evolved. Using them, we can address questions such as: What is the nature of the first episode of star formation in dwarf galaxies? Are dwarf galaxies able to accrete a significant amount of gas at later times, or is the bulk of the gas in place once the dwarf galaxy establishes its gravitational identity? What processes are responsible for the conversion from gas-rich to gas-poor dwarf galaxies? In the current epoch, we have a wealth of observations which allow us to study the character of the interstellar medium and the process of star formation. How does the interstellar medium change as a function of metallicity? Are there different modes of star formation for different physical conditions (metallicity, mass surface density)? Spatially resolved, recent star formation histories allow us to ask fundamental questions such as: What conditions are required for star formation? What is the impact of the star formation on the structure of the ISM? Does star formation heat the ISM and consequently suppress future star formation, or does it compress the ISM and lead to more star formation? Does understanding star formation at z = 0 help us to understand star formation at higher redshifts?
Achieving type safety for low-level code

Type-safe, high-level languages such as Java ensure that a wide class of failures, including buffer overruns and format string attacks, simply cannot happen. Unfortunately, our computing infrastructure is built with type-unsafe low-level languages such as C, and it is economically impossible to throw away our existing operating systems, databases, routers, etc. and re-code them all in Java.
The Genomic Impacts of Drift and Selection for Hybrid Performance in Maize

Although maize is naturally an outcrossing organism, modern breeding utilizes highly inbred lines in controlled crosses to produce hybrids. The U.S. Department of Agriculture's reciprocal recurrent selection experiment between the Iowa Stiff Stalk Synthetic (BSSS) and the Iowa Corn Borer Synthetic No. 1 (BSCB1) populations represents one of the longest running experiments to understand the response to selection for hybrid performance. To investigate the genomic impact of this selection program, we genotyped the progenitor lines and >600 individuals across multiple cycles of selection using a genome-wide panel of ∼40,000 SNPs. We confirmed previous results showing a steady temporal decrease in genetic diversity within populations and a corresponding increase in differentiation between populations. Thanks to detailed historical information on experimental design, we were able to perform extensive simulations using founder haplotypes to replicate the experiment in the absence of selection. These simulations demonstrate that while most of the observed reduction in genetic diversity can be attributed to genetic drift, heterozygosity in each population has fallen more than expected. We then took advantage of our high-density genotype data to identify extensive regions of haplotype fixation and trace haplotype ancestry to single founder inbred lines. The vast majority of regions showing such evidence of selection differ between the two populations, providing evidence for the dominance model of heterosis. We discuss how this pattern is likely to occur during selection for hybrid performance and how it poses challenges for dissecting the impacts of modern breeding and selection on the maize genome.
Survival Distributions and Their Characteristics

The four basic functions that characterize the probability distribution of the time to an event are presented. These functions, the survival function, the density or mass function, the hazard rate, and the mean residual life function are presented, and the relationship between the functions is discussed. Classes of distributions that reflect aging properties are presented. These classes include the increasing hazard rate (IHR) class, the increasing hazard rate on the average class (IHRA), the decreasing mean residual life (DMRL) class, the new better than used (NBU) class, the new better than used in expectation class (NBUE) and the harmonic new better than used in expectation class (HNBUE). Keywords: survival function; hazard function; mean residual life; median residual life; aging classes
Bayesian meta-reasoning: determining model adequacy from within a small world

This paper presents a Bayesian framework for assessing the adequacy of a model without the necessity of explicitly enumerating a specific alternate model. A test statistic is developed for tracking the performance of the model across repeated problem instances. Asymptotic methods are used to derive an approximate distribution for the test statistic. When the model is rejected, the individual components of the test statistic can be used to guide search for an alternate model.
Inapproximability of $H$-Transversal/Packing

Given an undirected graph $G = (V_G, E_G)$ and a fixed “pattern” graph $H = (V_H, E_H)$ with $k$ vertices, we consider the $H$-Transversal and $H$-Packing problems. The former asks to find the smallest $S \subseteq V_G$ such that the subgraph induced by $V_G \setminus S$ does not have $H$ as a subgraph, and the latter asks to find the maximum number of pairwise disjoint $k$-subsets $S_1, \ldots, S_m \subseteq V_G$ such that the subgraph induced by each $S_i$ has $H$ as a subgraph. We prove that if $H$ is 2-connected, $H$-Transversal and $H$-Packing are almost as hard to approximate as general $k$-Hypergraph Vertex Cover and $k$-Set Packing, so it is NP-hard to approximate them within a factor of $\Omega (k)$ and $\widetilde \Omega (k)$, respectively. We also show that there is a 1-connected $H$ where $H$-Transversal admits an $O(\log k)$-approximation algorithm, so that the connectivity requirement cannot be relaxed from 2 to 1. For a special case of $H$-Transversal where $H$ is a (family of) cycles, we m...
Building galaxies by accretion and in-situ star formation

We examine galaxy formation in a cosmological AMR simulation, which includes two high resolution boxes, one centered on a 3 × 10 14 M⊙ cluster, and one centered on a void. We examine the evolution of 611 massive (M∗ > 10 10 M⊙) galaxies. We find that the fraction of the final stellar mass which is accreted from other galaxies is between 15 and 40% and increases with stellar mass. The accreted fraction does not depend strongly on environment at a given stellar mass, but the galaxies in groups and cluster environments are older and underwent mergers earlier than galaxies in lower density environments. On average, the accreted stars are � 2.5 Gyrs older, and � 0.15 dex more metal poor than the stars formed in-situ. Accreted stellar material typically lies on the outskirts of galaxies; the average half-light radius of the accreted stars is 2.6 times larger than that of the in-situ stars. This leads to radial gradients in age and metallicity for massive galaxies, in qualitative agreement with observations. Massive galaxies grow by mergers at a rate of approximately 2.6%/Gyr −1 . These mergers have a median (mass-weighted) mass ratio less than 0.26 ± 0.21, with an absolute lower limit of 0.20, for galaxies with M∗ � 10 12 M⊙. This suggests that major mergers do not dominate in the accretion history of massive galaxies. All of these results agree qualitatively with results from SPH simulations by Oser et al. (2010, 2012).
Toward a Graph Version of Rado's Theorem

An equation is called graph-regular if it always has monochromatic solutions under edge-colorings of $K_{\mathbb{N}}$. We present two Rado-like conditions which are respectively necessary and sufficient for an equation to be graph-regular.
Galactic Emission at 19 GHz

We cross-correlate a 19 GHz full sky cosmic microwave background survey with other maps to quantify the foreground contribution. Correlations are detected with the DIRBE 240, 140, and 100 μm maps at high latitudes (|b| > 30°), and marginal correlations are detected with the Haslam 408 MHz and the Reich & Reich 1420 MHz synchrotron maps. The former agree well with extrapolations from higher frequencies probed by the COBE Differential Microwave Radiometer and Saskatoon experiments and are consistent with both free-free and rotating dust grain emission.
On the Allocative Efficiency of Competitive Prices in Economies with Incomplete Markets

A new measure of constrained efficiency for application in economies with incomplete markets is presented. This measure --- termed Allais- Malinvaud efficiency --- can be viewed as adjusting for market incompleteness not fully captured in previous work. It is shown that equilibrium allocations in Radner-GEI economies are always Allais- Malinvaud efficient. In particular, a re-distribution of assets in equilibrium cannot induce a relative price change that leads to an Allais-Malinvaud improvement. Moreover, this result extends to Radner- GEI economies in which consumer liability is limited by bankruptcy.
Design of Bi-Tortuous, Anisotropic Graphite Anodes for Fast Ion-Transport in Li-Ion Batteries

Thick Li-ion battery electrodes with high ion transport rates could enable batteries that cost less and that have higher gravimetric and volumetric energy density, because they require fewer inactive cell-components. Finding ways to increase ion transport rates in thick electrodes would be especially valuable for electrodes made with graphite platelets, which have been shown to have tortuosities in the thru-plane direction about 3 times higher than in the in-plane direction. Here, we predict that bi-tortuous electrode structures (containing electrolyte-filled macro-pores embedded in micro-porous graphite) can enhance ion transport and can achieve double the discharge capacity compared to an unstructured electrode at the same average porosity. We introduce a new two-dimensional version of porous-electrode theory with anisotropic ion transport to investigate these effects and to interpret the mechanisms by which performance enhancements arise. From this analysis we determine criteria for the design of bi-tortuous graphite anodes, including the particular volume fraction of macro-pores that maximizes discharge capacity (approximately 20 vol.%) and a threshold spacing interval (half the electrode's thickness) below which only marginal enhancement in discharge capacity is obtained. We also report the sensitivity of performance with respect to cycling rate, electrode thickness, and average porosity/electroactive-material loading.
What determines cross-border bank lending and risk-taking? The effects of culture, geography, institutions, and information exchange

We explore the effects of culture, regulation, and geographical factors on bilateral cross-border bank lending. Using a newly compiled dataset on BIS-reporting banks’ activities, we find that geographical factors, information flows and common institutional arrangements are the primary drivers of bilateral bank lending. Trust between individuals in the two countries matters only as a proxy for other cultural similarities. The relationship between bank regulatory differences and lending flows has changed over time. Before the crisis, banks made more cross-border loans in countries with regulations that promoted market discipline and transparency, but took on more risk in countries that had less transparency, perhaps in pursuit of higher returns. This relationship between transparency and banking flows has disappeared in the aftermath of the financial crisis.
Conceptual design of a charged particle beam energy spectrometer utilizing transition radiation grating

A new technique of measuring the energy spectrum of a charged particle beam using optical transition radiation is presented in this paper. The charged particle beam energy spectrum can be studied by analyzing the optical spectrum of the optical transition radiation produced in a multi-foil configuration. This type of energy spectrometer can have a very large energy acceptance which can not be matched by a simple conventional magnetic dipole spectrometer. The theory of transition radiation from a single boundary and from a foil with finite thickness are reviewed. Multi-foil transition radiation theory and its application for charged particle beam energy spectrum measurement are presented. The practical issues which might affect the performance of a multi-foil transition radiation energy spectrometer are discussed.
Finish them!: pricing algorithms for human computation

Given a batch of human computation tasks, a commonly ignored aspect is how the price (i.e., the reward paid to human workers) of these tasks must be set or varied in order to meet latency or cost constraints. Often, the price is set up-front and not modified, leading to either a much higher monetary cost than needed (if the price is set too high), or to a much larger latency than expected (if the price is set too low). Leveraging a pricing model from prior work, we develop algorithms to optimally set and then vary price over time in order to meet a (a) user-specified deadline while minimizing total monetary cost (b) user-specified monetary budget constraint while minimizing total elapsed time. We leverage techniques from decision theory (specifically, Markov Decision Processes) for both these problems, and demonstrate that our techniques lead to upto 30% reduction in cost over schemes proposed in prior work. Furthermore, we develop techniques to speed-up the computation, enabling users to leverage the price setting algorithms on-the-fly.
The Graphical Structure of Respondent-driven Sampling:

Respondent-driven sampling (RDS) is a chain-referral method for sampling members of hidden or hard-to-reach populations, such as sex workers, homeless people, or drug users, via their social networ...
Upper critical fields and superconducting anisotropy of K0.70Fe1.55Se1.01S0.99 and K0.76Fe1.61Se0.96S1.04 single crystals

We have investigated temperature and angular dependence of resistivity of K0.70(7)Fe1.55(7)Se1.01(2)S0.99(2) and K0.76(5)Fe1.61(5)Se0.96(4)S1.04(5) single crystals. The upper critical fields μ0Hc2(T) for both field directions decrease with the increase in S content. On the other hand, the angle-dependent magnetoresistivity for both compounds can be scaled onto one curve using the anisotropic Ginzburg-Landau theory. The obtained anisotropy of μ0Hc2(T) increases with S content, implying that S doping might decrease the dimensionality of certain Fermi surface parts, leading to stronger two-dimensional character.
Gaudin Model and Opers

This is a review of our previous works [FFR, F1, F3] (some of them joint with B. Feigin and N. Reshetikhin) on the Gaudin model and opers. We define a commutative subalgebra in the tensor power of the universal enveloping algebra of a simple Lie algebra \(\mathfrak{g}\). This algebra includes the Hamiltonians of the Gaudin model, hence we call it the Gaudin algebra. It is constructed as a quotient of the center of the completed enveloping algebra of the affine Kac-Moody algebra \({\hat g}\) at the critical level. We identify the spectrum of the Gaudin algebra with the space of opers associated to the Langlands dual Lie algebra L \(\mathfrak{g}\) on the projective line with regular singularities at the marked points. Next, we recall the construction of the eigenvectors of the Gaudin algebra using the Wakimoto modules over \({\hat g}\) of critical level. The Wakimoto modules are naturally parameterized by Miura opers (or, equivalently, Cartan connections), and the action of the center on them is given by the Miura transformation. This allows us to relate solutions of the Bethe Ansatz equations to Miura opers and ultimately to the flag varieties associated to the Langlands dual Lie algebra L \(\mathfrak{g}\).
An Adaptive Coherent Optical Receiver Array

Abstract : A linear, four-element, adaptive heterodyne optical receiver array employing semiconductor lasers is described. The array adaptively adjusts the phase of each subaperture IF signal to correct for wavefront tilt and distortion and nonuniform optical and RF path delays across the array by phase locking each channel to a reference channel. (Author)
Minireview: Emerging Concepts in Islet Macrophage Biology in Type 2 Diabetes

Chronic systemic inflammation is a hallmark feature of obesity and type 2 diabetes. Both resident and recruited islet macrophages contribute to the proinflammatory milieu of the diabetic islet. However, macrophages also appear to be critical for β-cell formation during development and support β-cell replication in experimental models of pancreas regeneration. In light of these findings, perhaps macrophages in the islet need to be viewed more as a fulcrum where deleterious inflammatory activation is balanced with beneficial tissue repair processes. Undoubtedly, defining the factors that contribute to the ontogeny, heterogeneity, and functionality of macrophages in normal, diseased, and regenerating islets will be necessary to determine whether that fulcrum can be moved to preserve functional β-cell mass in persons with diabetes. The intent of this review is to introduce the reader to emerging concepts of islet macrophage biology that may challenge the perception that macrophage accumulation in islets is merely a pathological feature of type 2 diabetes.
Managers’ Incorporation of the Value of Real Options into Their Long‐Term Investment Decisions: An Experimental Investigation*

While academic and practitioner literature has advocated the use of real options in firms’ longterm investment appraisal processes, few studies have examined the extent to which real options are incorporated into decisions when they are available for decision-making. Using two experiments, we examine supervising managers’ reliance on real options values in their decisions about funding for subordinates’ long-term investment project proposals. We predict and find with Experiment 1 that when making funding decisions, supervising managers rely less on the value of real options than on the value of a project’s planned implementation path. We predict and find with Experiment 2 that, holding information constant, a simple accounting change influences supervisors’ reliance on real options values in their funding decisions: they rely more on the real options components of project value when the amount is aggregated with (rather than displayed separately from) the value of the projects’ planned implementation paths in a financial summary of subordinates’ proposals. We provide evidence of the process underlying how the financial summary affects funding decisions – specifically, it does so by influencing perceptions of the relative accuracy of the planned path and real options components of value. Results for both experiments hold after controlling for participants’ knowledge of discounted cash flow and real options valuation and perceptions of risk in subordinates’ projects.
Spectrophotometric calibration system for DECam

We describe a spectrophotometric calibration system that is being implemented as part of the DES DECam project at the Blanco 4 meter at CTIO. Our calibration system uses a 1nm wide tunable source to measure the instrumental response function of the telescope optics and detector from 300nm up to 1100nm. This calibration will be performed regularly to monitor any change in the transmission function of the telescope during the 5 year survey. The system consists of a monochromator based tunable light source that provides illumination on a dome flat that is monitored by calibrated photodiodes that allow us to measure the telescope throughput as a function of wavelength. Our system has a peak output power of 2 mW, equivalent to a flux of approximately 800 photons/s/pixel on DECam.
Substituting Symbol for Substance: What Did Brown Really Accomplish?

(Kluger 1976, 710), Brown, it is claimed, "profoundly affected national thinking and has served as the principal ideological engine" of the civil rights movement (Greenberg 1968, 1522). Brown has long served as the "symbol" of the courts' ability to produce significant social reform (Neier 1982, 57), the "principal inspiration to others who seek change through litigation" (Greenberg 1974, 331). As Wilkinson puts it, "Brown may be the most important political, social, and legal event in America's twentieth-century history" (1979, 6). It has served, Robert Cover tells us, as a "paradigmatic event" (1982, 1316). Despite its enduring importance, major claims made about Brown are highly questionable: that the decision made a difference in
Exit option in hierarchical agency

Abstract We explain why organizations that limit the voice of their agents can benefit from granting them an exit option. We study a hierarchy with a principal, a productive supervisor and an agent. Communication is imperfect in that only the supervisor can communicate with the principal, while the agent has no direct voice to the principal. We show that the principal is better off if she grants the agent the option to walk away from the contract. By doing so, the principal is implicitly giving a “veto” power to the agent. This, in turn, restricts the manipulation of report by the supervisor. Thus, the exit option can be interpreted as a remedy for limits on communication. Our finding contrasts to the traditional result from the contract theory literature that the exit option reduces the principal's welfare, while protecting the agent. Our result is robust to the case of collusion between the supervisor and the agent. We also examine the optimal exit option, i.e., whether exit should entail a payment to or from the agent.
Interlayer pairing and c-axis versus ab-plane gap anisotropy in high-Tc superconductors

Abstract Interlayer BCS-like pairing in nearly two-dimensional superconductors with N =1, 2 conducting layers per unit cell is investigated. For N =1, the singlet Δ s and triplet Δ t , order parameters have identical T c 's ( T cs = T ct ) and magnitudes, and the gap is isotropic. For N = 2, T cs ⩾ T ct and | Δ s |⩾ Δ t . In region I of the parameters, the gap is anisotropic and nodeless for T T cs . In region II, the gap has nodes near T cs but is nodeless at low T . In a magnetic field, non-unitary states are possible. For N = 1 (2), intra-and interlayer pairing are completely (essentially) incompatible.
Laboratory Studies of Fluid Flow Through Borehole Seals

Three experiments performed on cement borehole seals in granite indicate flow through the seal is slightly lower than flow through the intact rock. The experiments were performed at stress states simulating depths of approximately 350, 700, and 1000 meters.
The GATT and gradualism

Abstract This paper shows how the institutional rules imposed on its signatories by the GATT created a strategic incentive for countries to liberalize gradually. Trade liberalization must be gradual, and free trade can never be achieved, if punishment for deviation from an agreement is limited to a ‘withdrawal of equivalent concessions’ and if initial deviation from an agreement is also limited. The paper shows how (sufficiently patient) countries have an incentive to deviate in a limited way when operating under GATT dispute settlement procedures.
On the feasibility of a monetary union in the Southern Africa Development Community

This paper investigates the feasibility of a monetary union in Southern Africa Development Community (SADC) by looking at evidence of nominal exchange rate and inflation convergence. Using a methodology based on estimating time-varying parameters, the evidence suggests non-convergence. The non-convergence of nominal exchange rate and consumer price inflation suggests that presently the chances of SADC member countries satisfying some form of Maastricht-type criteria is quite low. Copyright © 2007 John Wiley & Sons, Ltd.
Single-step radiosynthesis and in vivo evaluation of a novel fluorine-18 labeled hippurate for use as a PET renal agent.

Abstract Objective The objective of this study was to investigate a new fluorine-18 labeled hippurate, m -cyano- p -[ 18 F]fluorohippurate ([ 18 F]CNPFH), as a potential radiopharmaceutical for evaluating renal function by PET. Methods [ 18 F]CNPFH was synthesized by a direct one-step nucleophilic aromatic substitution using an 18 F-for-[N(CH 3 ) 3 ] + -reaction. In vivo stability was determined by HPLC analysis of urine collected from a healthy rat at 30min p.i. of [ 18 F]CNPFH. The plasma protein binding (PPB) and erythrocyte uptake of [ 18 F]CNPFH were determined using blood collected from healthy rats at 5min p.i. Biodistribution studies were conducted in healthy rats at 10min and 1h p.i. of [ 18 F]CNPFH. Dynamic PET/CT imaging data were acquired in normal rats. For comparison, the same rats underwent an identical imaging study using the previously reported p -[ 18 F]fluorohippurate ([ 18 F]PFH) renal agent. Results [ 18 F]CNPFH demonstrated high in vivo stability with no metabolic degradation. The in vivo PPB and erythrocyte uptake of [ 18 F]CNPFH were found to be comparable to those of [ 18 F]PFH. Biodistribution and dynamic PET/CT imaging studies revealed a rapid clearance of [ 18 F]CNPFH primarily through the renal–urinary pathway. However, unlike [ 18 F]PFH, a minor (about 12%) fraction was eliminated via the hepatobiliary route. The PET-derived [ 18 F]CNPFH renograms revealed an average time-to-peak (T max ) of 3.2±0.4min which was similar to [ 18 F]PFH, but the average time-to-half-maximal activity (11.4±2.8min) was found to be higher than that of [ 18 F]PFH (7.1±1.3min). Conclusions Our in vivo results indicate that [ 18 F]CNPFH has renogram characteristics similar to those of [ 18 F]PFH, however, the unexpected hepatobiliary elimination is adding undesirable background signal in the PET images.
Gender and the Coaching Profession

If only 49.9% of the women's Division I college athletic teams are coached by women (Acosta & Carpenter, 1985a), then based on extrapolation it seems that women hold about 25% of all Division I coaching positions. Although a few researchers have investigated the reasons for this skewed gender ratio, they have used the individual model that assumes the worker shapes the workplace. In contrast, this author attempts to explain male domination of the profession using an organizational model based on the assumption that the structure of the workplace shapes the worker. This model is the basis for Kanter's (1977) theory in which she identifies three structural determinants of the workplace that shape gender differentiated work behavior. This author explores the shape of these determinants—opportunity, power, and proportion in the coaching profession—to determine how they may affect the number of females who enter and leave the coaching profession. The discussion of each determinant is accompanied by suggestions...
Femtosecond electron and x-ray source based on laser wakefield accelerator

A terawatt tabletop laser wakefield acceleration source of relativistic electrons has been developed in our Terawatt Ultrafast High Field Facility (TUHFF). The preliminary results for ultrafast radiolysis of liquid water using this femtosecond electron source are presented. A TUHFF based femtosecond x-ray source is proposed. Thomson scattering of the accelerated electrons off a counterpropagating terawatt laser beam will be used to generate keV x-ray photons. The expected parameters of this x-ray source have been estimated. The short pulse duration, high flux, and good collimation of the resulting x-ray beam would be conducive for ultrafast time-resolved x-ray absorption studies of short-lived transient species in gases, liquids, and solids. It is argued that the solvation dynamics of Br atoms generated in photoinduced electron detachment from aqueous bromide would make a convenient choice for the first pump-probe experiment using this x-ray source.