cssi/SciSciGPT-SciSciNet huggingface dataset:
Modeling and measurement of the ALS U5 undulator end magnetic structures

The end structures for the ALS U5.0 undulators utilize a system of dual permanent magnet rotors intended to establish gap independent field performance. They may also be used for tuning of the first and second magnetic field integrals of these devices. The behavior of these structures has been studied by means of two dimensional modeling with the POISSON Group of computer codes. A parametric study of the magnetic field distribution and first and second integrals of the fields has been conducted. In parallel, magnetic measurements of the final completed structures have been performed using an automated Hall probe measurement system. Results of the modeling and measurements are compared. Implications for tuning of the ends of the devices within the context of the electron beam parameters of the ALS are discussed. >
Symmetry of information: a closer look

Symmetry of information establishes a relation between the information that x has about y (denoted I(x : y)) and the information that y has about x (denoted I(y : x)). In classical information theory, the two are exactly equal, but in algorithmical information theory, there is a small excess quantity of information that differentiates the two terms, caused by the necessity of packaging information in a way that makes it accessible to algorithms. It was shown in [Zim11] that in the case of strings with simple complexity (that is the Kolmogorov complexity of their Kolmogorov complexity is small), the relevant information can be packed in a very economical way, which leads to a tighter relation between I(x : y) and I(y : x) than the one provided in the classical symmetry-of-information theorem of Kolmogorov and Levin. We give here a simpler proof of this result.
Models and Mechanisms for Artificial Morphogenesis

Embryological development provides an inspiring example of the creation of complex hierarchical structures by self-organization. Likewise, biological metamorphosis shows how these complex systems can radically restructure themselves. Our research investigates these principles and their application to artificial systems in order to create intricately structured systems that are ordered from the nanoscale up to the macroscale. However these processes depend on mutually interdependent unfoldings of an information process and of the “body” in which it is occurring. Such embodied computation provides challenges as well as opportunities, and in order to fulfill its promise, we need both formal and informal models for conceptualizing, designing, and reasoning about embodied computation. This paper presents a preliminary design for one such model especially oriented toward artificial morphogenesis.
Development of a Simple Method for Concentrating Enteroviruses from Oysters

The development of a simple method for concentrating enteroviruses from oysters is described. In this method viruses in homogenized oyster tissues are efficiently adsorbed to oyster solids at pH 5.5 and low salt concentration. After low-speed centrifugation, the supernatant is discarded and viruses are eluted from the sedimented oyster solids by resuspending them in pH 3.5 glycine-buffered saline. The solids are then removed by low-speed centrifugation, and the virus-containing supernatant is filtered through a 0.2-μm porosity filter to remove bacteria and other small particulates without removing viruses. The virus-containing filtrate is then concentrated to a volume of a few milliliters by ultrafiltration, and the concentrate obtained is inoculated directly into cell cultures for virus assay. When tested with pools of oysters experimentally contaminated with small amounts of different enteroviruses, virus recovery efficiency averaged 63%.
Programs as polypeptides

Object-oriented combinator chemistry OOCC is an artificial chemistry with composition devices borrowed from object-oriented and functional programming languages. Actors in OOCC are embedded in space and subject to diffusion; since they are neither created nor destroyed, their mass is conserved. Actors use programs constructed from combinators to asynchronously update their own states and the states of other actors in their neighborhoods. The fact that programs and combinators are themselves reified as actors makes it possible to build programs that build programs from combinators of a few primitive types using asynchronous spatial processes that resemble chemistry as much as computation. To demonstrate this, OOCC is used to define a parallel, asynchronous, spatially distributed self-replicating system modeled in part on the living cell. Since interactions among its parts result in the construction of more of these same parts, the system is strongly constructive. The system's high normalized complexity is contrasted with that of a simple composome.
A remark on the existence of suitable vector fields related to the dynamics of scalar semi-linear parabolic equations

In 1992, P. Polacik showed that one could linearly imbed any vector field into a scalar semi-linear parabolic equation on Ω with Neumann boundary condition provided that there exists a smooth vector field Φ= (Φ 1 ,···Φ n ) on? such that formula math. In this short paper, we give a classification of all the domains on which one may find such a type of vector field.
Exit and save : migration and saving under violence

This paper examines how households trade off migration and savings when subject to exogenous violence. The authors propose that households under violence decide jointly on migration and saving, because a higher asset-stock is more difficult to carry to a new place. When confronted with exogenous violence, households are expected to consider migration, and reduce their assets, both in order to reduce their exposure to violence, and to make migration easier. In some cases, after a migration decision has been taken, savings can increase as a function of violence to ensure a minimum bundle to carry. Empirical evidence from rich Colombian micro-data supports the conceptual framework for violence that carries a displacement threat, such as guerrilla attacks.
When is the Ball a Local Pessimum for Covering

We consider the problem of identifying the worst point-symmetric shape for covering $$n$$n-dimensional Euclidean space with lattice translates. Here we focus on the dimensions where the thinnest lattice covering with balls is known and ask whether the ball is a pessimum for covering in these dimensions compared to all point-symmetric convex shapes. We find that the ball is a local pessimum in 3 dimensions, but not so in 4 and 5 dimensions.
Modifying Bayesian networks by probability constraints

This paper deals with the following problem: modify a Bayesian network to satisfy a given set of probability constraints by only change its conditional probability tables, and the probability distribution of the resulting network should be as close as possible to that of the original network. We propose to solve this problem by extending IPFP (iterative proportional fitting procedure) to probability distributions represented by Bayesian networks. The resulting algorithm E-IPFP is further developed to D-IPFP, which reduces the computational cost by decomposing a global E-IPFP into a set of smaller local E-IPFP problems. Limited analysis is provided, including the convergence proofs of the two algorithms. Computer experiments were conducted to validate the algorithms. The results are consistent with the theoretical analysis.
Mass Spectrometry and Gas‐Phase Ion Chemistry of Organomanganese Complexes

This review (782 references) represents an exhaustive up-to-date survey of literature on mass spectrometry and gas-phase ion chemistry of organomanganese complexes. Fundamental physico-chemical characteristics of organomanganese ionic species, as well as the gas-phase reactions resulting in the dissociation or formation of manganese-carbon bond(s) are examined. Circa 300 examples of ion/molecule reactions characterizing the reactivity of Mn+, positively or negatively charged manganese clusters, as well as neutrals, cations and anions of various Mn-containing species (including coordinatively unsaturated ones) are summarized. A variety of studies involving tandem mass spectrometry, neutralization-reionization mass spectrometry, collision-induced dissociation, multiple-photon dissociation, IRMPD spectroscopy and theoretical calculations for organomanganese ion structure characterization are discussed. Additionally, analytical applications of mass spectrometric techniques to the characterization of compounds containing a MnC bond are reviewed. These include a number of relatively simple mononuclear complexes, polynuclear clusters, complexes incorporating organometallic units bridged with organic fragment(s), bifunctional compounds containing organometallic and classical Werner-type coordination sites, fullerenes or planar polyaromatic hydrocarbons with an organomanganese fragment attached to them, manganospiralenes, manganoscorpionates, supramolecular entities, cymantrene-peptide bioconjugates, etc. Keywords: bond dissociation energy; collision-induced dissociation; gas-phase ion chemistry; ion/molecule reaction; ionization method; IRMPD spectroscopy; isomer differentiation; mass spectrometry; molecular ion; photoelectron spectroscopy
Affecting policy by manipulating prediction markets: Experimental evidence

Abstract Documented results indicate prediction markets effectively aggregate information and form accurate predictions. This has led to a proliferation of markets predicting everything from the results of elections to a company's sales to movie box office receipts. Recent research suggests prediction markets are robust to manipulation attacks and resulting market outcomes improve forecast accuracy. However, we present evidence from the lab indicating that single-minded, well-funded manipulators can in fact destroy a prediction market's ability to aggregate informative prices and mislead those who are making forecasts based upon market predictions. However, we find that manipulators primarily influence market trades meaning outstanding bids and asks remain informative.
Quasi-Bayesian strategies for efficient plan generation: application to the planning to observe problem

Quasi-Bayesian theory uses convex sets of probability distributions and expected loss to represent preferences about plans. The theory focuses on decision robustness, i.e., the extent to which plans are affected by deviations in subjective assessments of probability. Generating a plan means enumerating the actions to be taken and providing information about the robustness of the actions. The present work presents plan generation problems that can be solved faster in the Quasi-Bayesian framework than within usual Bayesian theory. We investigate this on the planning to observe problem, i.e., an agent must decide whether to take new observations or not. The fundamental question is: How, and how much, to search for a "best" plan, based on the precision of probability assessments? Plan generation algorithms are derived in the context of material classification with an acoustic robotic probe. A package that constructs Quasi-Bayesian plans is available through anonymous ftp.
The roles of translation initiation regulation in ultraviolet light-induced apoptosis

Proc Amer Assoc Cancer Res, Volume 47, 2006 4394 Ultraviolet light (UV) inhibits translation initiation through activation of the kinases that phosphorylate the α-subunit of eukaryotic initiation factor 2 (eIF2α). Two eIF2α kinases, PERK and GCN2, are known to phosphorylate the Serine-51 of eIF2α in response to UV-irradiation. In this report, we present evidence that phosphorylation of eIF2α plays a role in UV-induced apoptosis. Our data show that wild-type mouse embryo fibroblasts [MEF(S/S)] are less sensitive to UV-induced apoptosis than MEF(A/A) cells in which the phosphorylation site, Ser51, of eIF2α is replaced with a non-phosphorylatable Ala (Ser51Ala). PARP expression in MEF(A/A) cells is reduced without being cleaved after UV-irradiation. In con trast, PARP is cleaved without a significant decrease in parental PARP in MEF(S/S) cells after UV-irradiation. Our data also show that MEF(GCN2−/−) cells, in which GCN2 is knocked out, are more sensitive to UV-irradiation, which agrees with the observation from MEF(A/A) cells. However, MEF(PERK−/−) cells, in which PERK is knocked out, are less sensitive to UV-irradiation. In addition, MCF-7-PERKΔC cells, which are stably transfected with a kinase domain deleted mutant of PERK (PERKΔC), are more resistant to UV-induced apoptosis than parental MCF-7 cells. Overexpression of wild-type PERK sensitizes MCF-7 cells to UV-induced apoptosis without directly inducing cell death. These results suggest that the level of eIF2α phosphorylation impacts PARP expression upon UV-irradiation. The eIF2α kinases may mediate UV-induced apoptosis via an eIF2α dependent or independent signaling pathway.
Policy Rule Coefficients Driven by Latent Factors: Monetary and Fiscal Policy Interactions in an Endowment Economy

In this paper I formulate, solve and estimate an endowment version of a macroeconomic dynamic stochastic general equilibrium model with monetary and fiscal policy rules whose coefficients are time-varying and contemporaneously correlated. The aim of the paper is to identify from data the interactions between monetary and fiscal policies that have prevailed in the U.S. economy. The monetary authority uses a Taylor rule and the fiscal authority uses a rule in which taxes respond to lagged debt deviations. Policy rule coefficients are modeled as logistic functions of stationary correlated latent factors, introducing long-run interactions between monetary and fiscal policies. There are three main findings of the paper: First, monetary policy has reacted strongly to inflation deviations along, almost, the entire analyzed period, with a loose policy only during the periods 1979:1-1981:3 and 2008:4-2009:2. Second, regimes under which a determinacy condition is in place occur 54.25% of the time, while regimes with exploding local dynamics occur 45.34% of the time, and there is an association between the duration of these unstable regimes and the volatility of inflation. Third, tightening monetary policy in terms of increasing the reaction of the central bank with respect to inflation deviations, given the situation of the economy in the third quarter of 2010, implies an increase in inflation of the order of 3%.
A short and constructive proof of Tarski’s fixed-point theorem

I give short and constructive proofs of Tarski’s fixed-point theorem, and of Zhou’s extension of Tarski’s fixed-point theorem to set-valued maps.
Quantitative treatment of decoherence

We review several approaches to define and quantify decoherence. We find that a measure based on a norm of deviation of the density matrix is appropriate for quantifying decoherence for quantum registers. For a semiconductor double quantum-dot charge qubit, evaluation of this measure is presented. For a general class of decoherence processes, including those occurring in semiconductor qubits, we establish that this measure is additive: It scales linearly with the number of qubits in the quantum register.
The HgF2 Ionic Switch: A Triumph of Electrostatics against Relativistic Odds

A remarkable transition in the chemical bonding in (HgF2)n clusters as a function of n is identified and characterized. HgF2 is a fascinating material. Certain significant consequences of relativistic effects on the structure of the HgF2 molecule, dimer, and trimer disappear in the extended solid. Relativistic effects in Hg ensure that HgX2 molecules (X≡F, Cl, Br, and I) are linear, rigid, and form weakly bound dimers and trimers held together by weak electrostatic and van der Waals-type forces (unlike ZnX2 and CdX2 systems in which the intermonomer contacts are strong polar covalent bonds). For HgF2, the location and nature of an apparent transition from weak interactions in the smallest (HgF2)n clusters to ionic bonding in the (fluorite) HgF2 extended solid has remained a mystery. Computational evidence obtained at the M06-2X, B97D3, and MP2 levels of theory and reported herein indicate that polar covalent bonding in (HgF2)n begins as early as n=5. For n=2 through to n=13, the transition or switch from weak (primarily dipole-dipole-type) intermonomer interactions to a preference for polar covalent bonding occurs within the range 5<n≤9. Thermodynamic evidence for this transition is provided. Our results demonstrate a significant risk associated with crystal structure prediction from the ground up (i.e., based on bonding patterns in small clusters). The path from monomers through to extended solids may be punctuated at one or several points (as n increases) with transitions in structure and bonding that are not anticipated or betrayed by the bonding in small clusters.
The topological complexity and the homotopy cofiber of the diagonal map for non-orientable surfaces

We show that the Lusternik-Schnirelmann category of the homotopy cofiber of the diagonal map for non-orientable surfaces equals three. Also, we prove that the topological complexity of non-orientable surfaces of genus $>3$ is four.
Economic Development and the Effectiveness of Foreign Aid: A Historical Perspective

type="main"> Summary In this paper I discuss the effectiveness of foreign aid from a historical perspective. I show that foreign aid is a relatively new concept in economics, and I emphasize the role of exchange rate policies in the foreign aid controversies of the 1970s through 1990s. I show that in the early 1980s there were major changes in views regarding aid and agriculture. I emphasize the role of “ownership” of aid programs by the recipient countries as a way of increasing effectiveness. I argue that there is little hope of making progress in these debates if the economics profession continues to rely, almost exclusively, on cross section regressions. In order to move forward, these analyses need to be supplemented by in depth case studies that follow a country's history for many decades.
Union Power, Replacement and Labour Market Dynamics

In this paper, we construct a new basis for insider--outsider theory that acknowledges that insiders are typically easier to organise, so that they can delegate their bargaining decisions to a representative if they want to. We show that harassment or discrimination of new workers by the insider work force is neither individually rational nor needed to explain union formation or inefficient hiring decisions. However, we show that there is a strong tendency for overemployment. Unions tend to increase the efficiency of hiring decisions although union contracts will look like inducing underemployment.
Security Enforced Mediation Systems for Data Integration

Mediation techniques support integrated query processing among heterogeneous databases. While such techniques help data sharing among different distributed sources, they increase the risk for data security, such as violating access control rule. Successful protection of information by an effective access control mechanism is a basic requirement for data integration among heterogeneous sources. How to protect the object with fine-granularity, how to support the access control specification at different points, and how to support the semantic heterogeneity in the access control become the major challenges in the data protection of the mediation system. Currently few existing approaches address all three security challenges inmediation system. With the purpose of solving the aforementioned challenges faced by the access control in mediation system, we present an architectural and practical solution to assure the data security in the process of data integration from different sources.
Models and selection criteria for regression and classification

When performing regression or classification, we are interested in the conditional probability distribution for an outcome or class variable Y given a set of explanatory or input variables X. We consider Bayesian models for this task. In particular, we examine a special class of models, which we call Bayesian regression/classification (BRC) models, that can be factored into independent conditional (y[x) and input (x) models. These models are convenient, because the conditional model (the portion of the full model that we care about) can be analyzed by itself. We examine the practice of transforming arbitrary Bayesian models to BRC models, and argue that this practice is often inappropriate because it ignores prior knowledge that may be important for learning. In addition, we examine Bayesian methods for learning models from data. We discuss two criteria for Bayesian model selection that are appropriate for repression/classification: one described by Spiegelhalter etah (1993), and other by Buntine (1993). We contrast these two criteria using the prequentia] framework of Dawid (1984), and give sufficient conditions under which the criteria agree.
A heuristic approach to the quantum measurement problem: How to distinguish particle detectors from ordinary objects

Elementary particle detectors fall broadly into only two classes: phase-transformation devices, such as the bubble chamber, and charge-transfer devices like the Geiger–Muller tube. Quantum measurements are seen to involve transitions from a long-lived metastable state (e.g., superheated liquid or a gas of atoms between charged capacitor plates) to a thermodynamically stable condition. A detector is then a specially prepared object undergoing a metastable-to-stable transformation that is significantly enhanced by the presence of the measured particle, which behaves, in some sense, as the seed of a process of heterogeneous nucleation. Based on this understanding of the operation of a conventional detector, and using results of orthogonality-catastrophe theory, we argue that, in the thermodynamic limit, the pre-measurement Hamiltonian is not the same as that describing the detector during or after the interaction with a particle and, thus, that superpositions of pointer states (Schrodinger’s cats) are unphys...
Coding for Random Projections

The method of random projections has become popular for large-scale applications in statistical learning, information retrieval, bio-informatics and other applications. Using a well-designed coding scheme for the projected data, which determines the number of bits needed for each projected value and how to allocate these bits, can significantly improve the effectiveness of the algorithm, in storage cost as well as computational speed. In this paper, we study a number of simple coding schemes, focusing on the task of similarity estimation and on an application to training linear classifiers. We demonstrate that uniform quantization outperforms the standard and influential method (Datar et al., 2004), which used a window-and-random offset scheme. Indeed, we argue that in many cases coding with just a small number of bits suffices. Furthermore, we also develop a non-uniform 2-bit coding scheme that generally performs well in practice, as confirmed by our experiments on training linear support vector machines (SVM). Proofs and additional experiments are available at arXiv:1308.2218. In the context of using coded random projections for approximate near neighbor search by building hash tables (arXiv:1403.8144) (Li et al., 2014), we show that the step of random off-set in (Datar et al., 2004) is again not needed and may hurt the performance. Furthermore, we show that, unless the target similarity level is high, it usually suffices to use only 1 or 2 bits to code each hashed value for this task. Section 7 presents some experimental results for LSH.
The Distribution of H2O Maser Emission in the Nucleus of NGC 4945

We present the first interferometer map of the H2O maser emission in the active nucleus of NGC 4945, which exhibits both starburst and Seyfert qualities. Although the declination of the galaxy is -49°, we were able to make the observations with the southernmost antennas of the Very Long Baseline Array. Strong maser emission is present in three velocity ranges, one near the systemic velocity and two shifted roughly symmetrically by ±(100-150) km s-1. This is the first detection of highly blueshifted water emission in NGC 4945. We also report a marginal detection of previously unreported redshifted emission at a velocity of about +200 km s-1 with respect to the systemic velocity. From fringe rate analysis we determined the position of the maser to be α1950 = 13h02m3228 ± 002; δ1950 = -49°12'019 ± 01. The uncertainties in earlier estimates are at least several arcseconds. The maser lies within 2'' (36 pc at a distance of 3.7 Mpc) of the peaks in 1.4 GHz continuum and 1.6 μm emission from the nucleus. The mappable maser emission is distributed roughly linearly over ≈ 40 milliarcseconds (0.7 pc) at a position angle of ≈ 45°, which is close to the 43° ± 2° position angle of the galactic disk. The red- and blueshifted emission symmetrically straddle the systemic emission on the sky, which suggests material in edge-on circular motion around a central object. The position-velocity structure indicates a binding mass of ~1 × 106 M☉, within a volume of radius ≈ 0.3 pc, which in combination with estimates of the AGN luminosity, implies that the central engine radiates on the order of 10% of its Eddington luminosity.
Environmental Justice as Civil Rights

Environmental justice litigation using the Equal Protection Clause and civil rights statutes has largely failed. This article explains that failure as a result of a general shift by federal courts to limit the scope of civil rights law rather than an improper characterization of environmental justice as a civil rights issue. This explanation is important to both encourage and caution environmental justice advocates and scholars as they approach claims under Title VIII. I suggest that Title VIII's ability to bridge property and dignity may still present a powerful and much-needed tool for bringing equality to environmental law, but that, based on recent treatment of civil rights in the courts, those concepts should be bridged outside of the civil rights context first. Thus, I recommend that environmental justice scholars and advocates shift their focus from litigating civil rights claims to building the conceptual and doctrinal connection between environmental quality, property, and personal dignity through the administrative process, tort suits, and other means before making the leap to Title VIII.
The Formation of Galactic Spheroids

The spheroidal components of galaxies, including globular clusters, are usually assumed to form during a period of rapid collapse and high luminosity. A few years ago, I developed in collaboration with Martin Rees, a theory for the origin of globular clusters (Fall and Rees 1985. 1988). We showed that realistic density or velocity perturbations in a protogalaxy would be amplified during the collapse. The result is a two-phase medium with some gas at the virial temperature, a few × 106K, and some gas at the temperture that hydrogen recombines, about 104K. The density of the hot gas can be derived from fairly general arguments, and since the two phases must be in rough pressure balance, the density and Jeans mass of the cold gas can be calculated with some confidence. We found that clouds with masses of order 106 M. would collapse gravitationally, and should therefore be identified as the progenitors of globular clusters. The condition for this mass scale to be “imprinted” is that the temperatures of the clouds remain near 104K for at least one free-fall time. Once the protogalactic gas has been enriched in heavy elements from the first generation of stars in globular clusters, cooling becomes more efficient and much smaller clouds can collapse, thereby promoting the formation of later generations of field stars. We therefore expect that on average globular clusters should have lower abundances of heavy elements and more extended space distributions than the field stars in the spheroidal components of galaxies. As the result of various selection biases, these predictions are not easy to test for the Milky Way but they are consistent with a growing body of data for other galaxies (Forte, Strom and Strom 1981, Harris 1986, 1987, Mould 1987, Mould, Oke and Nemec 1987, Elson and Walterbos 1987).
Single-visit more effective than multiple-visit root canal treatment?*

Data sources: Literature was searched using the Cochrane Controlled Trials Register (CENTRAL), Medline, Embase and HealthStar databases. Reference lists from identified articles were scanned and a further search made using names of authors of the identified articles. Papers that had cited these publications were also identified through the Science Citation Index to identify potentially relevant subsequent primary research. Study selection: Two reviewers scanned all titles and abstracts. An article was included if subjects had a no relevant medical history; subjects presented with mature teeth with infected necrotic root canals and radiographic evidence of periapical bone loss (as an indication of preoperative canal infection), all selected root canals had not received any endodontic treatment previously, participants underwent nonsurgical root canal treatment during the study, and the number of teeth showing radiographic evidence of healing was the outcome measure. Data extraction and synthesis: Data were abstracted by two reviewers. The principal measure of treatment effect was risk difference with the fixed-effect method for combining study estimates being used to produce an overall estimate. Between-study heterogeneity was assessed using standard x2 test or Q-statistic. Results: Only three randomized controlled trials (RCT) were identified and included in the review, covering a total of 146 cases. Sample size of all three studies was small. None demonstrated a statistically significant difference in healing rates. Risk differences (RD) of included studies were combined using the inverse variance-weighted method (pooled RD, -6.3%; 95% confidence interval, -20.3 to +7.8). Conclusions: Based on the current best available evidence, single-visit root canal treatment appears to be slightly more effective than multiple visits, that is, it had a 6.3% higher healing rate. The difference in healing rate between these two treatment regimens was not statistically significant (P= 0.3809), however.
Parental Education and Children’s Schooling Outcomes : Is the Effect Nature, Nurture, or Both? Evidence from Recomposed Families in Rwanda

Educated parents tend to have educated children. But is intergenerational transmission of human capital more nature, more nurture, or both? The author uses household survey data from Rwanda that contains a large proportion of children living in households without their biological parents. The data allows him to separate genetic from environmental parental influences. The nonrandom placement of children is controlled by including the educational attainment of the absent biological parents and the type of relationship that links the children to their"adoptive"families. The results of the analysis suggest that the nurture component of the intergenerational transmission of human capital is important for both parents, contrary to recent evidence proposed by Behrman and Rosenzweig (2002) and Plug (2004). The author concludes that mothers’ education had no environmental impact on children’s schooling. Interestingly, mothers’ education matters more for girls, while fathers’ education is more important for boys. Finally, an important policy recommendation in the African context emerges from the analysis: the risk for orphans or abandoned children to lose ground in their schooling achievements is minimized if they are placed with relatives.
Firm productivity and infrastructure costs in east Africa

Infrastructure is an important driving force for economic growth. It reduces trade and transaction costs and stimulates the productivity of the economy. Africa has been lagging behind in the global manufacturing market. Among others, infrastructure is an important constraint in many African countries. Using firm-level data for East Africa, the paper reexamines the relationship between firm performance and infrastructure. It is shown that labor costs are by far the most important to stimulate firm production. Among the infrastructure sectors, electricity costs have the highest output elasticity, followed by transport costs. In addition, the paper shows that the quality of infrastructure is important to increase firm production. In particular, quality transport infrastructure seems to be essential. The paper also finds that agglomeration economies can reduce firm costs. The agglomeration elasticity is estimated at 0.03–0.04.
On Elevating Strategic Design Research

While the popular understanding of the influence of design is growing, academic research has largely been restricted to considering consumer-level responses to design elements. This paper reviews this past work and proposes a more strategic research agenda for the field, with the potential to explicate linkages between design elements and strategies and outcomes related to innovation and corporate performance.
Coarse Differentiation and Multi-flows in Planar Graphs

We show that the multi-commodity max-flow/min-cut gap for series-parallel graphs can be as bad as 2, matching a recent upper bound (Chakrabarti et al. in 49th Annual Symposium on Foundations of Computer Science, pp. 761–770, 2008) for this class, and resolving one side of a conjecture of Gupta, Newman, Rabinovich, and Sinclair. This also improves the largest known gap for planar graphs from $\frac{3}{2}$to 2, yielding the first lower bound that does not follow from elementary calculations. Our approach uses the coarse differentiation method of Eskin, Fisher, and Whyte in order to lower bound the distortion for embedding a particular family of shortest-path metrics into L 1.
The Impact of Monetary Policy Surprises on Energy Prices

This paper examines the effect of monetary policy surprises on energy prices at intraday, daily, and monthly frequencies. We measure monetary policy shocks using changes in interest rate futures prices that capture unexpected changes in the fed funds target rate. We find a significant response of energy prices to surprise changes in the fed funds target rate in an intraday window immediately following the monetary announcement. However, the accumulated responses of energy prices to monetary shocks over a period of several days after the announcement are statistically insignificant. We also use fed funds futures data to identify the contemporaneous impact of monetary policy shocks on oil prices in a monthly structural vector autoregressive (VAR) setup. We find no statistically significant effect of federal funds rate shocks on oil prices. The VAR estimates support the assumption of no contemporaneous feedback from monetary policy to energy prices. © 2013 Wiley Periodicals, Inc. Jrl Fut Mark 35:87–103, 2015
Spatial and Temporal Proximity: Examining the Effects of Protests on Political Attitudes

This article utilizes data from the Latino National Survey (2006) to analyze temporal and spatial variation in the effects of the immigrant rights marches in 2006 on Latino attitudes towards trust in government and self-efficacy. Using a unique protest dataset, we examine the effects of proximity and scale by mapping respondents’ specific geographic location against the location of the marches as well as size of the protests using Geographic Information Systems (GIS). We find that local proximity to small marches had a positive impact on feelings of efficacy, whereas large-scale protests led to lower feelings of efficacy. The results shed light on the role localized political events can play in shaping feelings towards government, the importance of conceptions of space and time to the study of social movements, and the positive outcomes that can result from contentious politics.
Finiteness and the falsification by fellow traveler property

We prove that groups enjoying the falsification by fellow traveler property are of type F3, and have at most an exponential second-order isoperimetric function.
Minimal length maximal green sequences and triangulations of polygons

We use combinatorics of quivers and the corresponding surfaces to study maximal green sequences of minimal length for quivers of type $$\mathbb {A}$$A. We prove that such sequences have length $$n+t$$n+t, where n is the number of vertices and t is the number of 3-cycles in the quiver. Moreover, we develop a procedure that yields these minimal length maximal green sequences.
On considering uncertainty and alternatives in low-level vision

In this paper we address the uncertainty issues involved in the low-level vision task of image segmentation. Researchers in computer vision have worked extensively on this problem, in which the goal is to partition (or segment) an image into regions that are homogeneous or uniform in some sense. This segmentation is often utilized by some higher-level process, such as an object recognition system. We show that by considering uncertainty in a Bayesian formalism, we can use statistical image models to build an approximate representation of a probability distribution over a space of alternative segmentations. We give detailed descriptions of the various levels of uncertainty associated with this problem, discuss the interaction of prior and posterior distributions, and provide the operations for constructing this representation.
Design of Spatially Coupled LDPC Codes Over GF $(q)$ for Windowed Decoding

In this paper, we study spatially coupled low-density parity-check (SC-LDPC) codes over finite fields GF $(q)$ , $q\geq 2$ , and develop design rules for $q$ -ary SC-LDPC code ensembles based on their iterative belief propagation decoding thresholds, with particular emphasis on low-latency windowed decoding (WD). We consider transmission over both the binary erasure channel (BEC) and the binary-input additive white Gaussian noise channel (BIAWGNC) and present results for a variety of $(J,K)$ -regular SC-LDPC code ensembles constructed over GF $(q)$ using protographs. Thresholds are calculated using the protograph versions of $q$ -ary density evolution (for the BEC) and the $q$ -ary extrinsic information transfer analysis (for the BIAWGNC). We show that the WD of $q$ -ary SC-LDPC codes provides significant threshold gains compared with corresponding (uncoupled) $q$ -ary LDPC block code (LDPC-BC) ensembles when the window size $W$ is large enough and that these gains increase as the finite-field size $q=2^{m}$ increases. Moreover, we demonstrate that the new design rules provide WD thresholds that are close to capacity, even when both $m$ and $W$ are relatively small (thereby reducing decoding complexity and latency). The analysis further shows that, compared with standard flooding-schedule decoding, the WD of $q$ -ary SC-LDPC code ensembles results in significant reductions in both the decoding complexity and the decoding latency and that these reductions increase as $m$ increases. For the applications with a near-threshold performance requirement and a constraint on decoding latency, we show that using $q$ -ary SC-LDPC code ensembles, with moderate $q>2$ , instead of their binary counterparts results in reduced decoding complexity.
Comparison of solar concentrators

Abstract Even though most variations of solar concentrators have been studied or built at some time or other, an important class of concentrators has been overlooked until very recently. These novel concentrators have been called ideal because of their optical properties, and an example, the compound parabolic concentrator, is being tested at Argonne National Laboratory. Ideal concentrators differ radically from conventional instruments such as focussing parabolas. They act as radiation funnel and do not have a focus. For a given acceptance angle their concentration surpasses that of other solar concentrators by a factor of two to four, but a rather large reflector area is required. The number of reflections varies with angle of incidence, with an average value around one in most cases of interest. In order to help provide a rational basis for deciding which concentrator type is best suited for a particular application, we have compared a variety of solar concentrators in terms of their most important general characteristics, namely concentration, acceptance angle, sensitivity to mirror errors, size of reflector area and average number of reflections. The connection between concentration, acceptance angle and operating temperature of a solar collector is analysed in simple intuitive terms, leading to a straightforward recipe for designing collectors with maximal concentration (no radiation emitted by the absorber must be allowed to leave the concentrator outside its acceptance angle). We propose some new concentrators, including the use of compound parabolic concentrators as second stage concentrators for conventional parabolic or Fresnel mirrors. Such a combination approaches the performance of an ideal concentrator without demanding a large reflector; it may offer significant advantages for high temperature solar systems.
Continuous Cluster Categories I

In Igusa and Todorov(2013) we constructed topological triangulated categories \(\mathcal {C}_{c}\) as stable categories of certain topological Frobenius categories \(\mathcal {F}_{c}\). In this paper we show that these categories have a cluster structure for certain values of c including c = π. The continuous cluster categories are those \(\mathcal {C}_{c}\) which have cluster structure. We study the basic structure of these cluster categories and we show that \(\mathcal {C}_{c}\) is isomorphic to an orbit category \(\mathcal {D}_{r}/\underline F_{s}\) of the continuous derived category\(\mathcal {D}_{r}\) if c = rπ/s. In \(\mathcal {C}_{\pi }\), a cluster is equivalent to a discrete lamination of the hyperbolic plane. We give the representation theoretic interpretation of these clusters and laminations.
$BC_n$-symmetric abelian functions

We construct a family of BC_n-symmetric biorthogonal abelian functions generalizing Koornwinder's orthogonal polynomials, and prove a number of their properties, most notably analogues of Macdonald's conjectures. The construction is based on a direct construction for a special case generalizing Okounkov's interpolation polynomials. We show that these interpolation functions satisfy a collection of generalized hypergeometric identities, including new multivariate elliptic analogues of Jackson's summation and Bailey's transformation.
Impact of a double-pigtail stent on ureteral peristalsis in the porcine model: Initial studies using a novel implantable magnetic sensor

Background and Purpose: The effect of stents on ureteral peristalsis in vivo is not entirely clear. We sought to develop a minimally invasive method for its study. Materials and Methods: In female domestic pigs, electrical potentials from the ureter were measured by bipolar steel-wire electromyography electrodes delivered laparoscopically. Mechanical movement was measured by giant magneto resistive sensors mounted on custom-made aluminum strips. After baseline values were obtained, the animals were randomized to receive silicone or polyurethane stents, and ureteral peristalsis was measured for 8 hours acutely and for 4 hours 1 week later. Results: Implantation of the devices took an average of 30 minutes. A consistent correlation was found between laparoscopically observed peristaltic waves and the peristalsis detected by the two measuring devices. The devices themselves did not affect peristalsis. Stent insertion increased peristaltic activity initially but later reduced or stopped it. There was no diffe...
Eclipsing Binaries: Tools for Calibrating the Extragalactic Distance Scale

In the last decade, over 7000 eclipsing binaries have been discovered in the Local Group through various variability surveys. Measuring fundamental parameters of these eclipsing binaries has become feasible with 8 meter class telescopes, making it possible to use eclipsing binaries as distance indicators. Distances with eclipsing binaries provide an independent method for calibrating the extragalactic distance scale and thus determining the Hubble constant. This method has been used for determining distances to eclipsing binaries in the Magellanic Clouds and the Andromeda Galaxy and most recently to a detached eclipsing binary in the Triangulum Galaxy by the DIRECT Project. The increasing number of eclipsing binaries found by microlens- ing and variability surveys also provide a rich database for advancing our understanding of star formation and evolution.
The linearization of the central limit operator in free probability theory

We interpret the Central Limit Theorem as a fixed point theorem for a certain operator, and consider the problem of linearizing this operator. In classical as well as in free probability theory [VDN92], we consider two methods giving such a linearization, and interpret the result as a weak form of the CLT. In the classical case the analysis involves dilation operators; in the free case more general composition operators appear.
Hot, Rotating Disks in General Relativity: Collisionless Equilibrium Models

We present a method for constructing equilibrium disks with net angular momentum in general relativity. The method solves the relativistic Vlasov equation coupled to Einstein's equations for the gravitational field. We apply the method to construct disks that are relativistic versions of Newtonian Kalnajs disks. In Newtonian gravity these disks are analytic and are stable against ring formation for certain ranges of their velocity dispersion. We investigate the existence of fully general relativistic equilibrium sequences for differing values of the velocity dispersion. These models are the first rotating, relativistic disk solutions of the collisionless Boltzmann equation.
Improvements in the Synthesis and Understanding of the Iodo-bridged Intermediate en Route to the Pt(IV) Prodrug Satraplatin

Mixed amine/ammine motifs are important features in newer generation platinum anticancer agents, including the Pt(IV) prodrug satraplatin. One synthetic route that can be used to access platinum molecules with such structures exploits the trans effect during NH3-mediated cleavage of iodo-bridged platinum(II) dimers of the form [Pt(Am)I(μ-I)]2, where Am is an amine. A clear picture of the nature of these dimers that is consistent with the reactivity they exhibit has remained elusive. Moreover, technical aspects of this chemistry have impeded its more widespread use. We present here an improved strategy that permits isolation and use of [Pt(Am)I(μ-I)]2, where Am is cyclohexylamine, within minutes as opposed to weeks, as previously reported. A detailed spectroscopic, crystallographic, and chromatographic investigation of this intermediate in the synthesis of satraplatin is also presented with a discussion of the ability of both cis and trans isomers of the dimer to produce exclusively cis-[Pt(NH2C6H11)(NH3)I2] upon treatment with NH3.
Interpretation of D(2637) From Heavy Quark Symmetry

We demonstrate from heavy quark symmetry that the width of D(2637) claimed by the DELPHI Collaboration is inconsistent with any bound state with one charm quark predicted in the D(2637) mass region, except possibly the D-wave orbitally excited states and or the radially excited state D′. The former two possibilities are favoured by heavy quark mass relations.
A prime C∗-algebra that is not primitive

We construct a nonseparable C∗-algebra that is prime but not primitive. This solves an old problem of Dixmier.