cssi/SciSciGPT-SciSciNet huggingface dataset:
Some Estimates of Dissipation from Turbulent Velocity Component Gradients Over a Forest Canopy

Measurements of vector air velocities at two levels above a conifer canopy for 2 separate days were used to estimate the dissipation rate for turbulent energy following an analysis relating the dissipation to the spatial structure function for turbulent scales small compared to the height above the canopy. The rates were averaged for half-hour intervals and compared with estimates of production and the local divergence of the advective and diffusive fluxes of energy for 2 days; one with a forest fetch and one with an upwind forest edge. The dissipation estimates for the forest fetch were similar in magnitude to published measurements over a comparable canopy and qualitatively consistent with estimates of the other terms in the turbulent energy balance. Estimated net transport divergence is small as is the production by the turbulent sensible heat flux. The results dcwnwind of the forest edge indicate larger dissipation values and a greater excess of dissipation over production apparently reflecting turbulence production at the edge.
When Choices are Mistakes

Using a laboratory experiment, we identify whether decision makers consider it a mistake to violate canonical choice axioms. To do this, we incentivize subjects to report which of several axioms they want their decisions to satisfy. Then, subjects make lottery choices which might conflict with their stated axiom preferences. We give them the opportunity to re-evaluate their decisions when lotteries conflict with desired axioms. We find that a majority of individuals want to follow the axioms and revise their lottery choices to be consistent with them. We interpret this to mean that most axiom violations in our sample were mistakes.
Ultrasound-guided cervical selective nerve root injections: a narrative review of literature

Background/Importance Ultrasound (US)-guided cervical selective nerve root injections (CSNRI) have been proposed as an alternative to fluoroscopic (FL) -guided injections. When choosing US guidance, the proceduralist should be aware of potential issues confirming vertebral level, be clear regarding terminology, and up to date regarding the advantages and disadvantages of US-guided CSNRI. Objective Review the accuracy and effectiveness of US guidance in avoiding vascular puncture (VP) and/or intravascular injection (IVI) during CSNRI. Evidence Review Queries included PubMed, CINAHL and Embase databases from 2005 to 2019. Three authors reviewed references for eligibility, abstracted data, and appraised quality. Findings The literature demonstrates distinct safety considerations and limited evidence of the effectiveness of US guidance in detecting VP and/or IVI. As vascular flow and desired injectate spread cannot be visualized with US, the use of real-time fluoroscopy, and if needed digitial subraction imaging, is indicated in cervical transforaminal epidural injections (CTFEIs). Given the risk of VP and/or IVI, the ability to perform and to retain FL images to document that the procedure was safely conducted is valuable in CTFEIs. Conclusion US guidance remains to be proven as a non-inferior alternative to FL guidance or other imaging modalities in the prevention of VP and/or IVI with CTFEIs or cervical selective nerve root blocks. There is a paucity of adequately powered clinical studies evaluating the accuracy and effectiveness of US guidance in avoiding VP and/or IVI. US-guided procedures to treat cervical radicular pain has limitations in visualization of anatomy, and currently with the evidence available is best used in a combined approach with FL guidance.
Electrical Measurement of Cell-to-Cell Variation of Critical Charge in SRAM and Sensitivity to Single-Event Upsets by Low-Energy Protons

The distribution of single-event upsets (SEUs) in commercial off-the-shelf (COTS) static random access memory (SRAM) has generally been thought to be uniform in a device. However, process-induced variation within a device gives rise to variation within the cell-level electrical characteristic known as the data retention voltage ( $V_{\mathrm{ DR}}$ ). Furthermore, $V_{\mathrm{ DR}}$ has been shown to directly influence the critical charge ( $Q_{\mathrm{ C}}$ ) necessary for stored data to upset. Low-energy proton irradiation of COTS SRAMs exhibits a preference toward upsetting cells with lower $Q_{\mathrm{ C}}$ . An electrical procedure is presented to map relative cell critical charge values without knowledge of the underlying circuitry, allowing customized device usage. Given cell-level $Q_{\mathrm{ C}}$ knowledge, a device can have its cells “screened” such that those with low $Q_{\mathrm{ C}}$ are not used to store data. This work presents the results such a screening process has on the SEU per bit cross section.
An Investigation to Explain Structural Racism Associated with Michigan Public Charter Districts Funding Effort

The research objective is to explain evidence of structural racism, inequity, and inadequacy in the Michigan public school finance system related to the education of Black students or Black descend...
Machine Learning Highlights Downtrending of COVID-19 Patients with a Distinct Laboratory Profile

Background. New York City (NYC) experienced an initial surge and gradual decline in the number of SARS-CoV-2-confirmed cases in 2020. A change in the pattern of laboratory test results in COVID-19 patients over this time has not been reported or correlated with patient outcome. Methods. We performed a retrospective study of routine laboratory and SARS-CoV-2 RT-PCR test results from 5,785 patients evaluated in a NYC hospital emergency department from March to June employing machine learning analysis. Results. A COVID-19 high-risk laboratory test result profile (COVID19-HRP), consisting of 21 routine blood tests, was identified to characterize the SARS-CoV-2 patients. Approximately half of the SARS-CoV-2 positive patients had the distinct COVID19-HRP that separated them from SARS-CoV-2 negative patients. SARS-CoV-2 patients with the COVID19-HRP had higher SARS-CoV-2 viral loads, determined by cycle threshold values from the RT-PCR, and poorer clinical outcome compared to other positive patients without the COVID12-HRP. Furthermore, the percentage of SARS-CoV-2 patients with the COVID19-HRP has significantly decreased from March/April to May/June. Notably, viral load in the SARS-CoV-2 patients declined, and their laboratory profile became less distinguishable from SARS-CoV-2 negative patients in the later phase. Conclusions. Our longitudinal analysis illustrates the temporal change of laboratory test result profile in SARS-CoV-2 patients and the COVID-19 evolvement in a US epicenter. This analysis could become an important tool in COVID-19 population disease severity tracking and prediction. In addition, this analysis may play an important role in prioritizing high-risk patients, assisting in patient triaging and optimizing the usage of resources.
Periprosthetic Femur Fractures After Total Hip Arthroplasty

As the number of total hip arthroplasty procedures continues to rise, periprosthetic fractures present an increasingly common and complex problem for orthopedic surgeons. Periprosthetic fracture of the femur requires the surgeon to simultaneously address bone loss, implant stability, and the fracture itself. Particularly for geriatric patients, the goal of treatment is stable fracture fixation with early mobilization. Femoral stem stability is one of the most important aspects of management. A periprosthetic femoral fracture with a loose stem is the most common scenario. In these situations, we recommend treatment with an uncemented long-stem revision construct. There are several other less commonly performed reconstruction options that surgeons may utilize based on bone quality and fracture characteristics. Complication rate after periprosthetic fracture is high, with mortality rates approaching those of hip fracture patients.
Feasibility of a Distributed Computer Traffic Control System

Abstract The feasibility of implementing a realtime, distributed computer, traffic control system is investigated in this paper. A centralized multimicroprocessor system is proposed, and an off-line optimization algorithm SIGOP II is chosen from existing algorithms and is modified for use in a distributed system. The modified program was run on a Motorola MC6800 microprocessor and the characteristics of the output are discussed. The memory requirement and execution time of the program are found to be acceptable and will not be an obstacle towards building such a distributed system.
Non-intrusive Scalable Memory Access Tracer

Memory access tracing is one of the widely used methods to evaluate, analyze, and optimize hardware and software designs. We are developing a non-intrusive, scalable, full-address-range memory tracer. The tracer hardware board is compliant with the JEDEC DDR3 DIMM form factor, and fits in a DIMM slot. It is so compact that we can populate up to 16 tracer boards in a 4-CPU server chassis, and record the commands and addresses of all the memory accesses. Each board drives four SSDs to record the memory access addresses without a break until the SSDs are full. For example, we can make a trace of a full SPECjbb 2005 run, which lasts 26 minutes and generates over 11TB trace data. In addition to recording memory accesses, it collects various types of statistical data, such as a large number of segmented read/write statistics and DRAM bank utilization rates, and displays them on the control dashboard in real time.
Languages and designs for probability judgment

Theories of subjective probability are viewed as formal languages for analyzing evidence and expressing degrees of belief. This article focuses on two probability language, the Bayesian language and the language of belief functions [199]. We describe and compare the semantics (i.e., the meaning of the scale) and the syntax (i.e., the formal calculus) of these languages. We also investigate some of the designs for probability judgment afforded by the two languages.
Retinocortical time exhibits spatial selectivity

We recorded simultaneous electroretinograms and visual evoked potentials to pattern-reversal stimulus in ten normal subjects employing check sizes subtending 7.5, 15, 30, 60, 120, 240 and 480 min of visual arc. The mean peak latency of the pattern electroretinogram (PERG) b wave decreased logarithmically with increasing check size. The mean peak latency of the pattern visual evoked potential (PVEP) P100 component was shortest for 30 min check size and was longer at both smaller and larger check sizes, a phenomenon termed spatial selectivity. Retinocortical time (RCT) was calculated as the latency difference between the PVEP P100 peak and the PERG b wave. The RCT also exhibited spatial selectivity similar to that of the PVEP P100 component; mean RCT was shortest for 30 min check size and was longer at both smaller and larger check sizes. Implications are discussed in light of our current knowledge of the origins of the PERG and PVEP and visual processing of pattern-reversal stimuli. Simultaneous recording of PERGs and PVEPs in patients with disease of the afferent visual pathways employing a large range of check sizes may increase the diagnostic sensitivity of visual electrophysiologic testing.
UMN-MapServer: a high-performance, interoperable, and open source web mapping and geo-spatial analysis system

Recent advances in Internet technologies, coupled with wide adoption of the web services paradigm and interoperability standards, makes the World Wide Web a popular vehicle for geo-spatial information distribution and online geo-processing. Web GIS is rapidly evolving and adapting to advances in Internet technologies. Web GISes are predominantly designed under a “thin-client / fat-server” paradigm. This approach has several disadvantages. For example, as the number of users increases, the load on the server increases and system performance decreases. Recently the focus has been shifted towards client-side Web GISes, which are heavy-duty, stand-alone systems. We take an opposing approach and present a load balancing client/server Web-based spatial analysis system, UMN-MapServer, and evaluate its performance in a regional natural resource mapping and analysis (NRAMS) application which utilizes biweekly AVHRR imagery and several other raster and vector geo-spatial datasets. We also evaluate alternative approaches and assess the pros and cons of our design and implementation. UMN-MapServer also implements several open standards, such as, WMS, WCS, GML and WFS. In this paper, we also describe in detail the WMS, WCS,and GML extensions from the interoperability point of view, and discuss issues related to adoption of such standards.
Wavelength Assignment to Minimize the Number of SONET ADMs in WDM Rings

Optical wavelength division multiplexing (WDM) rings are being deployed to support SONET/SDH self-healing rings. In such systems, multiple SONET/SDH self-healing rings are realized over a single physical optical ring through wavelength division multiplexing. The cost of such a system is dominated by the SONET add/drop multiplexers (ADMs). To minimize the system cost, algorithms must be developed to assign wavelengths to lightpaths in the system so that the number of ADMs required is minimized. This problem of optimal wavelength assignment to minimize the number of SONET ADMs is known to be NP-hard. Existing heuristic algorithms for this problem include the assign first heuristic, the iterative matching heuristic and the iterative merging heuristic. In this paper, we develop an integer linear programming (ILP) formulation for this problem, propose a new wavelength assignment heuristic, and evaluate the existing and the newly proposed heuristic using the ILP formulation. We conclude that the performance of the newly proposed heuristic is very close to optimal.
Weak gravity strongly constrains large-field axion inflation

Models of large-field inflation based on axion-like fields with shift symmetries can be simple and natural, and make a promising prediction of detectable primordial gravitational waves. The Weak Gravity Conjecture is known to constrain the simplest case in which a single compact axion descends from a gauge field in an extra dimension. We argue that the Weak Gravity Conjecture also constrains a variety of theories of multiple compact axions including N-flation and some alignment models. We show that other alignment models entail surprising consequences for how the mass spectrum of the theory varies across the axion moduli space, and hence can be excluded if further conjectures hold. In every case that we consider, plausible assumptions lead to field ranges that cannot be parametrically larger than M Pl. Our results are strongly suggestive of a general inconsistency in models of large-field inflation based on compact axions, and possibly of a more general principle forbidding super-Planckian field ranges.
Bayesian Nonparametric Modeling of Higher Order Markov Chains

We consider the problem of flexible modeling of higher order Markov chains when an upper bound on the order of the chain is known but the true order and nature of the serial dependence are unknown. We propose Bayesian nonparametric methodology based on conditional tensor factorizations, which can characterize any transition probability with a specified maximal order. The methodology selects the important lags and captures higher order interactions among the lags, while also facilitating calculation of Bayes factors for a variety of hypotheses of interest. We design efficient Markov chain Monte Carlo algorithms for posterior computation, allowing for uncertainty in the set of important lags to be included and in the nature and order of the serial dependence. The methods are illustrated using simulation experiments and real world applications. Supplementary materials for this article are available online.
Efficient computation of the Bergsma---Dassios sign covariance

In an extension of Kendall's $$\tau $$?, Bergsma and Dassios (Bernoulli 20(2):1006---1028, 2014) introduced a covariance measure $$\tau ^*$$?? for two ordinal random variables that vanishes if and only if the two variables are independent. For a sample of size n, a direct computation of $$t^*$$t?, the empirical version of $$\tau ^*$$??, requires $$O(n^4)$$O(n4) operations. We derive an algorithm that computes the statistic using only $$O \left( n^2\log (n)\right) $$On2log(n) operations.
Shale gas development and infant health: Evidence from Pennsylvania

Abstract This research exploits the introduction of shale gas wells in Pennsylvania in response to growing controversy around the drilling method of hydraulic fracturing. Using detailed location data on maternal addresses and GIS coordinates of gas wells, this study examines singleton births to mothers residing close to a shale gas well from 2003 to 2010 in Pennsylvania. The introduction of drilling increased low birth weight and decreased term birth weight on average among mothers living within 2.5 km of a well compared to mothers living within 2.5 km of a permitted well. Adverse effects were also detected using measures such as small for gestational age and APGAR scores, while no effects on gestation periods were found. In the intensive margin, an additional well is associated with a 7 percent increase in low birth weight, a 5 g reduction in term birth weight and a 3 percent increase in premature birth. These results are robust to other measures of infant health, many changes in specification and falsification tests. These findings suggest that shale gas development poses significant risks to human health.
The Informal Economy of Rostov Oblast on the Eve of the Ukrainian Refugee Crisis

Abstract Using a stochastic frontier production function at the raion (county) level of aggregation, Rostov Oblast rural economy's formal economic growth 2009–2013 is analyzed in conjunction with satellite luminosity data capturing both the formal and informal economy. Satellite luminosity data reveal a growing economy with higher levels of secondary education, access to a federal highway and availability of natural gas associated with wealthier raions. The region's ability to absorb unregistered Ukrainian refugees with both the wealthiest and one of the poorest performing raions right on the Ukrainian border is questionable though on the eve of the crisis most raions exhibited a growing informal and formal economy.
Chi-Square Distribution Properties †

This article complements the introductory article on the chi-square distribution, with details of its derivation as the distribution of the sum of squares of standard normal deviates, the density being a gamma function, and the relationship between its distribution function and that of the Poisson distribution. When the component normal distributions have nonzero mean, the sum of squares has a noncentral chi-square distribution, depending on a noncentrality parameter, the sum of squares of the normal means. This plays a role in determining the power of a chi-square test. Keywords: degrees of freedom; generating function; characteristic function; gamma function; beta function; Poisson distribution; noncentral chi-square; likelihood ratio
The Fairness Opinion Puzzle: Board Incentives, Information Asymmetry, and Bidding Strategy

Abstract The proliferation of fairness opinions promulgating “wide as Texas” price ranges is not only a seeming regulatory failure, it is a puzzle: why do 60 percent of target boards solicit seemingly worthless documents not required by law, while 40 percent of their peers do not? This article explains a fairness opinion as “cheap talk” between a board and public shareholders. In the Fairness Opinion Game, a board issues a fairness opinion to communicate with two shareholder generations: existing shareholders voting on the proposed sale of their shares and potential aftermarket buyers who would buy if the present transaction falls through. The game yields two equilibria: one where the board issues no opinions and one where Texas‐wide opinions emerge as equilibrium messages. We conclude that three factors determine a fairness opinion's width: the board’s private incentives, information asymmetry between the board and shareholders, and transaction costs incurred by aftermarket buyers.
Global Volatility and Forex Returns in East Asia

During 2001–2010, increases in mature market volatility were associated with declines in forex returns for East Asian economies, consistent with an overall ‘flight to safety’ effect. Estimates from GARCH models suggest that a 10 percentage point increase in mature market equity volatility generated an exchange rate depreciation of up to 3/4 percent. This sensitivity rose during a more tranquil subsample for some countries, reflecting their greater integration with global financial markets. Long-run forex volatility increased in Asian economies after 2008, reflecting the global reach of the financial crisis in mature markets. Unconditional standard deviations estimated from these models provide operational measures of ‘long-term’ and ‘excess’ volatility in forex markets.
Harmonic contents of and detailed study on a high-gain harmonic generation free electron laser

In this paper, we calculate the third harmonic of a High Gain Harmonic Generation (HGHG) Free Electron Laser (FEL) at saturation. In the HGHG FEL scheme, there is an external dispersion section, which provides an efficient microbunching. Study on the emittance effect in such an external dispersion section suggests a new optimization for the HGHG FEL. We finally discuss how to reduce the incoherent undulator radiation which is a noise with respect to the seed laser.
Uniqueness of the measure of maximal entropy for the squarefree flow

The squarefree flow is a natural dynamical system whose topological and ergodic properties are closely linked to the behavior of squarefree numbers. We prove that the squarefree flow carries a unique measure of maximal entropy and express this measure explicitly in terms of a skew-product of a Kronecker and a Bernoulli system. Using this characterization and a number-theoretic argument, we then show that the unique maximum entropy measure fails to possess the Gibbs property.
Broadcasting in time-division duplexing: A random linear network coding approach

We study random linear network coding for broadcasting in time division duplexing channels. We assume a packet erasure channel with nodes that cannot transmit and receive information simultaneously. The sender transmits coded data packets back-to-back before stopping to wait for the receivers to acknowledge the number of degrees of freedom, if any, that are required to decode correctly the information. We study the mean time to complete the transmission of a block of packets to all receivers. We also present a bound on the number of stops to wait for acknowledgement in order to complete transmission with probability at least 1 − e, for any e ≫ 0. We present analysis and numerical results showing that our scheme outperforms optimal scheduling policies for broadcast, in terms of the mean completion time. We provide a simple heuristic to compute the number of coded packets to be sent before stopping that achieves close to optimal performance with the advantage of a considerable reduction in the search time.
Dynamic Recurrent Neural Networks for Stable Adaptive Control of Wing Rock Motion

Abstract Wing Rock or limit cycle oscillation (LCO) in an aircraft is often caused by aerodynamic nonlinearities or mechanical hysteresis. A dynamic recurrent radial basis function neural networ~s (DR-RBF) are proposed for modelling the nonlinear hysteresis. The concept based on Preisach hysteresis model is used in the design of neural networks. The structure and memory mechanism in the hysteresis model is analogous to parallel connectivity and memory formation in neural networks. Adaptive control law based on minimisation of the energy function to ensure stability in the Lyapunov sense is presented.
Iterative join-graph propagation

The paper presents an iterative version of join-tree clustering that applies the message passing of join-tree clustering algorithm to join-graphs rather than to join-trees, iteratively. It is inspired by the success of Pearl's belief propagation algorithm (BP) as an iterative approximation scheme on one hand, and by a recently introduced mini-clustering (MC(i)) success as an anytime approximation method, on the other. The proposed Iterative Join-graph Propagation (IJGP) belongs to the class of generalized belief propagation methods, recently proposed using analogy with algorithms in statistical physics. Empirical evaluation of this approach on a number of problem classes demonstrates that even the most time-efficient variant is almost always superior to IBP and MC(i), and is sometimes more accurate by as much as several orders of magnitude.
Discrete State-Space Methods for the Study of Dynamic Economies

This code supports the text in Craig Burnside, Discrete State-Space Methods for the Study of Dynamic Economies, in Ramon Marimon and Andrew Scott (eds), Computational Methods for the Study of Dynamic Economies, Chapter 5, Oxford University Press. Non-linear models with a finite numbers of states can be solved exactly with discrete state-space methods. They are also an excellent approximation to models with a continuous state space. The software is described in paragraph 6 of the chapter. Two programs solve the asset pricing model with i.i.d shocks (apiid.m) and serially correlated shocks (apsco.m). Two other programs solve the one-sector growth model with the "Tauchen" (grtauch.m) and the "Baxter" (grbcr.m) methods. The other files are subroutines.
New vanadium selenites: centrosymmetric Ca2(VO2)2(SeO3)3(H2O)2, Sr2(VO2)2(SeO3)3, and Ba(V2O5)(SeO3), and noncentrosymmetric and polar A4(VO2)2(SeO3)4(Se2O5) (A = Sr2+ or Pb2+).

Five new vanadium selenites, Ca(2)(VO(2))(2)(SeO(3))(3)(H(2)O)(2), Sr(2)(VO(2))(2)(SeO(3))(3), Ba(V(2)O(5))(SeO(3)), Sr(4)(VO(2))(2)(SeO(3))(4)(Se(2)O(5)), and Pb(4)(VO(2))(2)(SeO(3))(4)(Se(2)O(5)), have been synthesized and characterized. Their crystal structures were determined by single crystal X-ray diffraction. The compounds exhibit one- or two-dimensional structures consisting of corner- and edge-shared VO(4), VO(5), VO(6), and SeO(3) polyhedra. Of the reported materials, A(4)(VO(2))(2)(SeO(3))(4)(Se(2)O(5)) (A = Sr(2+) or Pb(2+)) are noncentrosymmetric (NCS) and polar. Powder second-harmonic generation (SHG) measurements revealed SHG efficiencies of approximately 130 and 150 × α-SiO(2) for Sr(4)(VO(2))(2)(SeO(3))(4)(Se(2)O(5)) and Pb(4)(VO(2))(2)(SeO(3))(4)(Se(2)O(5)), respectively. Piezoelectric charge constants of 43 and 53 pm/V, and pyroelectric coefficients of -27 and -42 μC/m(2)·K at 70 °C were obtained for Sr(4)(VO(2))(2)(SeO(3))(4)(Se(2)O(5)) and Pb(4)(VO(2))(2)(SeO(3))(4)(Se(2)O(5)), respectively. Frequency dependent polarization measurements confirmed that the materials are not ferroelectric, that is, the observed polarization cannot be reversed. In addition, the lone-pair on the Se(4+) cation may be considered as stereo-active consistent with calculations. For all of the reported materials, infrared, UV-vis, thermogravimetric, and differential thermal analysis measurements were performed. Crystal data: Ca(2)(VO(2))(2)(SeO(3))(3)(H(2)O)(2), orthorhombic, space group Pnma (No. 62), a = 7.827(4) A, b = 16.764(5) A, c = 9.679(5) A, V = 1270.1(9) A(3), and Z = 4; Sr(2)(VO(2))(2)(SeO(3))(3), monoclinic, space group P2(1)/c (No. 12), a = 14.739(13) A, b = 9.788(8) A, c = 8.440(7) A, β = 96.881(11)°, V = 1208.8(18) A(3), and Z = 4; Ba(V(2)O(5))(SeO(3)), orthorhombic, space group Pnma (No. 62), a = 13.9287(7) A, b = 5.3787(3) A, c = 8.9853(5) A, V = 673.16(6) A(3), and Z = 4; Sr(4)(VO(2))(2)(SeO(3))(4)(Se(2)O(5)), orthorhombic, space group Fdd2 (No. 43), a = 25.161(3) A, b = 12.1579(15) A, c = 12.8592(16) A, V = 3933.7(8) A(3), and Z = 8; Pb(4)(VO(2))(2)(SeO(3))(4)(Se(2)O(5)), orthorhombic, space group Fdd2 (No. 43), a = 25.029(2) A, b = 12.2147(10) A, c = 13.0154(10) A, V = 3979.1(6) A(3), and Z = 8.
Telepresence—the future of telephony

BT is a leading international supplier of telepresence in the form of telephony. Telepresence enables “people as content”, and there are rapidly developing and wide-ranging opportunities for broadband, mobile, multimedia telepresence services. In marked contrast with the relatively ubiquitous and consistent telephone, our vision for future telepresence services encompasses a wide variety of “terminals”, ranging in physical scale from personal wearable devices through more conventional desktop or living room hardware to immersive room-based systems. This chapter focuses on our desktop work, outlining our vision for both business and residential services, and reporting early results from user experiments.
Learning Theories: Applications for Instruction in Constraint-Based Solid Modeling and Other Engineering Graphics Topics

Constraint-based modeling tools, as well as computer graphics tools in general, offer the user many choices in commands and techniques for creating graphics, which forces the user to have a strategy or plan as they proceed. The formulation of this plan is often dependent on the integration of existing knowledge and current factors, such as customer specifications and the time element assigned to the particular project. In addition, the user must have a thorough understanding of the software functionality and the ability to gather information related to implementing a particular modeling strategy. This process of strategy development and implementation coincides with components of learning theory. As engineering graphics educators, it is helpful to reflect on how students learn in our classrooms and laboratories as well as reflect on how we develop instruction. This paper outlines three theories of learning that are applicable to graphics education, discusses the assumptions about the learner and the learning environment, presents the components of learning for each theory, discusses major issues related to complex learning and designing instruction, and summarizes some of the criticisms and contributions to education of each theory. Indeed, a process is presented for applying elements of these learning theories to constraint-based modeling.
Parallel Homomorphic Encryption

In the problem of private outsourced computation, a client wishes to delegate the evaluation of a function f on a private input x to an untrusted worker without the latter learning anything about x and f(x). This problem occurs in many applications and, most notably, in the setting of cloud computing.
Entropy and Diffuse Scattering: Comparison of NbTiVZr and CrMoNbV

The chemical disorder intrinsic to high-entropy alloys inevitably creates diffuse scattering in their X-ray or neutron diffraction patterns. Through first principles hybrid Monte Carlo/molecular dynamics simulations of two BCC high-entropy alloy forming compounds, CrMoNbV and NbTiVZr, we identify the contributions of chemical disorder, atomic size, and thermal fluctuations to the diffuse scattering. As a side benefit, we evaluate the reduction in entropy due to pair correlations within the framework of the cluster variation method. Finally, we note that the preference of Ti and Zr for hexagonal structures at low temperature leads to a mechanical instability reducing the local BCC character of NbTiVZr, while preserving global BCC symmetry.
Genetic Algorithms for Solving Open Shop Scheduling Problems

In this paper we investigate the use of three evolutionary based heuristics to the open shop scheduling problem. The intractability of this problem is a motivation for the pursuit of heuristics that produce approximate solutions. This work introduces three evolutionary based heuristics, namely, a permutation genetic algorithm, a hybrid genetic algorithm and a selfish gene algorithm, and tests their applicability to the open shop scheduling problem. Several problem instances are used with our evolutionary based algorithms. We compare the results and conclude with some observations and suggestions on the use of evolutionary heuristics for scheduling problems. We also report on the success that our hybrid genetic algorithm has had on one of the large benchmark problem instances: our heuristic has produced a better solution than the current best known solution.
An evaluation of the 2014 subsidy reforms in Morocco and a simulation of further reforms

Under increasing budget pressure, Morocco carried out an extensive set of subsidy reforms in 2014 and is planning for further reforms for 2015–2017, which will eliminate most consumers' subsidies. This paper evaluates (ex post) the 2014 reforms and simulates (ex ante) the impact on household welfare, poverty, and the government budget of the total elimination of subsidies. The paper considers food and energy subsidies and estimates direct and indirect effects using SUBSIM, a subsidies simulation model designed by the World Bank. It finds that the 2014 reforms have been a good mix of reforms from a distributional, welfare, poverty, and government budget perspectives. They are perhaps the most rational reforms undertaken in the Middle East and North Africa region in recent years. The analysis also finds further reforms costly for the poor and more complex from a political economy perspective, especially for liquefied petroleum gas.
Efficient computation of the characteristic polynomial of a threshold graph

An efficient algorithm is presented to compute the characteristic polynomial of a threshold graph. Threshold graphs were introduced by Chvatal and Hammer, as well as by Henderson and Zalcstein in 1977. A threshold graph is obtained from a one vertex graph by repeatedly adding either an isolated vertex or a dominating vertex, which is a vertex adjacent to all the other vertices. Threshold graphs are special kinds of cographs, which themselves are special kinds of graphs of clique-width 2. We obtain a running time of O ( n log 2 ź n ) for computing the characteristic polynomial, while the previously fastest algorithm ran in quadratic time. We improve the running time drastically in the case where there is a small number of alternations between 0's and 1's in the sequence defining a threshold graph. A simple recurrence equation for the determinant of a weighted threshold graph matrix is presented.The characteristic polynomial is computed in O ( n log 2 ź n ) arithmetic operations.The algorithm is more efficient if the alternations in the defining sequence are o ( n ) .As the numbers may be of length n log ź n , the bit complexity is investigated too.
Ramanujan coverings of graphs

Abstract Let G be a finite connected graph, and let ρ be the spectral radius of its universal cover. For example, if G is k-regular then ρ = 2 k − 1 . We show that for every r, there is an r-covering (a.k.a. an r-lift) of G where all the new eigenvalues are bounded from above by ρ. It follows that a bipartite Ramanujan graph has a Ramanujan r-covering for every r. This generalizes the r = 2 case due to Marcus, Spielman and Srivastava [26] . Every r-covering of G corresponds to a labeling of the edges of G by elements of the symmetric group S r . We generalize this notion to labeling the edges by elements of various groups and present a broader scenario where Ramanujan coverings are guaranteed to exist. In particular, this shows the existence of richer families of bipartite Ramanujan graphs than was known before. Inspired by [26] , a crucial component of our proof is the existence of interlacing families of polynomials for complex reflection groups. The core argument of this component is taken from [27] . Another important ingredient of our proof is a new generalization of the matching polynomial of a graph. We define the r-th matching polynomial of G to be the average matching polynomial of all r-coverings of G. We show this polynomial shares many properties with the original matching polynomial. For example, it is real rooted with all its roots inside [ − ρ , ρ ] .
Defining and measuring policy coverage in testing access control policies

To facilitate managing access control in a system, security officers increasingly write access control policies in specification languages such as XACML, and use a dedicated software component called a Policy Decision Point (PDP). To increase confidence on written policies, certain types of policy testing (often in an ad hoc way) are usually conducted, which probe the PDP with some typical requests and check PDP's responses against expected ones. This paper develops a first step toward systematic policy testing by defining and measuring policy coverage when testing policies. We have developed a coverage-measurement tool to measure policy coverage given a set of XACML policies and a set of requests. We have developed a tool for request generation, which randomly generates requests for a given set of policies, and a tool for request reduction, which greedily selects a nearly minimal set of requests for achieving the same coverage as the originally generated requests. To evaluate coverage-based request reduction and its effect on fault detection, we have conducted an experiment with mutation testing on a set of real policies. Our experimental results show that the coveragebased test reduction can substantially reduce the size of generated requests and incur only relatively low loss on fault detection. We also conduct a study on the policy coverage achieved by manually generated requests.
BaRT: A Bayesian Reasoning Tool for Knowledge Based Systems

Abstract As the technology for building knowledge based systems has matured, important lessons have been learned about the relationship between the architecture of a system and the nature of the problems it is intended to solve. We are implementing a knowledge engineering tool called BART that is designed with these lessons in mind. BART is a Bayesian reasoning tool that makes belief networks and other probabilistic techniques available to knowledge engineers building classificatory problem solvers. BART has already been used to develop a decision aid for classifying ship images, and it is currently being used to manage uncertainty in systems concerned with analyzing intelligence reports. This paper discusses how state-of-the-art probabilistic methods fit naturally into a knowledge based approach to classificatory problem solving, and describes the current capabilities of BART.
Reducing GHG Emissions and Energy Input in the U.S. Supply Chain of Ethanol and Gasoline

The purpose of this study is to identify potential reductions of energy use2 and Green House Gases (GHG) emissions in the U.S. downstream (i.e., after production) supply chain of ethanol and gasoline fuels, by determining optimal transportation modes and routes. The analysis considers ethanol producers and fuel blending terminals, including consolidation and receiving hubs (Russell et al., 2009). Likewise transportation modes used for shipping ethanol are taken into account - rail, truck - in order to determine optimal delivery. Initial results support the need for construction of a new hub consolidation terminal or the expansion of the existing ones. This initial study leaves gasoline fuels, as well as shipments of ethanol via barge or vessel and of gasoline via pipeline, for a future extension.
Termination of Linear Programs

We show that termination of a class of linear loop programs is decidable. Linear loop programs are discrete-time linear systems with a loop condition governing termination, that is, a while loop with linear assignments. We relate the termination of such a simple loop, on all initial values, to the eigenvectors corresponding to only the positive real eigenvalues of the matrix defining the loop assignments. This characterization of termination is reminiscent of the famous stability theorems in control theory that characterize stability in terms of eigenvalues.
Efficiency and marginal cost pricing in dynamic competitive markets with friction

This paper examines a dynamic general equilibrium model with supply friction. With or without friction, the competitive equilibrium is efficient. Without friction, the market price is completely determined by the marginal production cost. If friction is present, no matter how small, then the market price fluctuates between zero and the "choke-up" price, without any tendency to converge to the marginal production cost, exhibiting considerable volatility. The distribution of the gains from trading in an efficient allocation may be skewed in favor of the supplier, although every player in the market is a price taker.
Selected Topics in Graphene Physics

Graphene research is currently one of the largest fields in condensed matter. Due to its unusual electronic spectrum with Dirac-like quasiparticles, and the fact that it is a unique example of a metallic membrane, graphene has properties that have no match in standard solid-state textbooks. In these lecture notes, I discuss some of these properties that are not covered in detail in recent reviews (Castro Neto AH, Guinea F, Peres NMR, Novoselov KS, Geim AK (2009) Rev Mod Phys 81:109). We study the particular aspects of the physics/chemistry of carbon that influence the properties of graphene; the basic features of graphene’s band structure including the \(\pi\) and \(\sigma\) bands; the phonon spectra in free floating graphene; the effects of a substrate on the structural properties of graphene; and the effect of deformations in the propagation of electrons. The objective of these notes is not to provide an unabridged theoretical description of graphene but to point out some of the peculiar aspects of this material.
Are climate model simulations of clouds improving? An evaluation using the ISCCP simulator

[1] The annual cycle climatology of cloud amount, cloud-top pressure, and optical thickness in two generations of climate models is compared to satellite observations to identify changes over time in the fidelity of simulated clouds. In more recent models, there is widespread reduction of a bias associated with too many highly reflective clouds, with the best models having eliminated this bias. With increased amounts of clouds with lesser reflectivity, the compensating errors that permit models to simulate the time-mean radiation balance have been reduced. Errors in cloud amount as a function of height or climate regime on average show little or no improvement, although greater improvement can be found in individual models.
Social protection for refugees and asylum seekers in the Southern Africa Development Community (SADC)

This report provides an overview of the provision of social protection to refugees and asylum seekers from Sub-Saharan Africa in the Southern African Development Community (SADC). This includes analyzing the legal framework and levels of implementation, as well as proposing policy directions on the national and regional levels. After giving an overview of the region's historical and legal context, the report focuses on the case studies of Botswana and South Africa to illustrate the wide variation of social protection framework and practices in the region.
Identifying approximate linear models for simple nonlinear systems

This paper addresses the identification (realization) of approximate linear models from response data for certain nonlinear dynamic systems. Response characteristics for several typical nonlinear joints are analyzed mathematically and represented by series expansions. The parameters of the series expansion are then compared with the modal parameters of a linear model identified by the Eigensystem Realization Algorithm. The agreement of the identified model and the analytically derived representation is excellent for the cases studied. Also laboratory data from a model which exhibited stiffening behavior was analyzed using the Eigensystem Realization algorithm and Fast Fourier Transform. The laboratory experiment demonstrated the ability of the technique to recover the model characteristics using real data.
Galaxies in the Universe: An Introduction

This extensively illustrated book presents the astrophysics of galaxies since their beginnings in the early Universe. It has been thoroughly revised to take into account the most recent observational data, and recent discoveries such as dark energy. There are new sections on galaxy clusters, gamma ray bursts and supermassive black holes. The authors explore the basic properties of stars and the Milky Way before working out towards nearby galaxies and the distant Universe. They discuss the structures of galaxies and how galaxies have developed, and relate this to the evolution of the Universe. The book also examines ways of observing galaxies across the whole electromagnetic spectrum, and explores dark matter and its gravitational pull on matter and light. This book is self-contained and includes several homework problems with hints. It is ideal for advanced undergraduate students in astronomy and astrophysics.
Towards a middleware framework for dynamically reconfigurable scietific computing

Computational grids are appealing platforms for the execution of large scale applications among the scientific and engineering communities. However, designing new applications and deploying existing ones with the capability of exploiting this potential still remains a challenge. Computational grids are characterized by their dynamic, non-dedicted, and heterogeneous nature. Novel application-level and middleware-level techniques are needed to allow applications to reconfigure themselves and adapt automatically to their underlying execution environments. In this paper, we introduce a new software framework that enhances the performance of Message Passing Interface (MPI) applications through an adaptive middleware for load balancing that includes process checkpointing and migration. Fields as diverse as fluid dynamics, materials science, biomechanics, and ecology make use of parallel adaptive computation. Target architectures have tradititionally been supercomputers and tightly coupled clusters. This framework is a first step in allowing these computations to use computational grids efficiently.
The interaction of silicon with positively charged carbon

Electron deficient species have long intrigued organic chemists. More than half a century ago, Whitmore developed the chemistry of carbocations here at Northwestern University and later at The Pennsylvania State University. The interaction of positively charged carbon with directly attached substituents that possess n or n electrons led to better understanding of the concept of conjugation, as in the familiar carbocations CH-CH-CH:, C6H5-CH:, and CH,O-CH: . The interaction with more remotely substituted groups, also possessing K or n electrons, as in PhCH,CH: or Me2NCH2CH:, led to the concepts of neighboring group participation and homoconjugation, In one of his last studies, Whitmore described the remarkable manner in which silyl substituents interact with positive charge on carbon. ’ In basic hydrolyses and ethanolyses, Whitmore and his co-workers found that a silyl group beta to the leaving group enormously enhances the rate of solvolysis, that a gamma silyl group also has an enhancing effect, but that an alpha silyl group actually decreases reactivity in comparison with hydrocarbon models. Sommer, a principal coworker with Whitmore on this study, went on to become one of the leading silicon chemists of his generation. The chart below summarizes possible structural relationships between a silicon-containing sub-