cssi/SciSciGPT-SciSciNet huggingface dataset:
Forced and unforced variability of twentieth century North American droughts and pluvials

Research on the forcing of drought and pluvial events over North America is dominated by general circulation model experiments that often have operational limitations (e.g., computational expense, ability to simulate relevant processes, etc). We use a statistically based modeling approach to investigate sea surface temperature (SST) forcing of the twentieth century pluvial (1905–1917) and drought (1932–1939, 1948–1957, 1998–2002) events. A principal component (PC) analysis of Palmer Drought Severity Index (PDSI) from the North American Drought Atlas separates the drought variability into five leading modes accounting for 62% of the underlying variance. Over the full period spanning these events (1900–2005), the first three PCs significantly correlate with SSTs in the equatorial Pacific (PC 1), North Pacific (PC 2), and North Atlantic (PC 3), with spatial patterns (as defined by the empirical orthogonal functions) consistent with our understanding of North American drought responses to SST forcing. We use a large ensemble statistical modeling approach to determine how successfully we can reproduce these drought/pluvial events using these three modes of variability. Using Pacific forcing only (PCs 1–2), we are able to reproduce the 1948–1957 drought and 1905–1917 pluvial above a 95% random noise threshold in over 90% of the ensemble members; the addition of Atlantic forcing (PCs 1–2–3) provides only marginal improvement. For the 1998–2002 drought, Pacific forcing reproduces the drought above noise in over 65% of the ensemble members, with the addition of Atlantic forcing increasing the number passing to over 80%. The severity of the drought, however, is underestimated in the ensemble median, suggesting this drought intensity can only be achieved through internal variability or other processes. Pacific only forcing does a poor job of reproducing the 1932–1939 drought pattern in the ensemble median, and less than one third of ensemble members exceed the noise threshold (28%). Inclusion of Atlantic forcing improves the ensemble median drought pattern and nearly doubles the number of ensemble members passing the noise threshold (52%). Even with the inclusion of Atlantic forcing, the intensity of the simulated 1932–1939 drought is muted, and the drought itself extends too far into the southwest and southern Great Plains. To an even greater extent than the 1998–2002 drought, these results suggest much of the variance in the 1932–1939 drought is dependent on processes other than SST forcing. This study highlights the importance of internal noise and non SST processes for hydroclimatic variability over North America, complementing existing research using general circulation models.
Intrinsic comparative statics of a general class of profit-maximizing rate-of-return regulated firms

An exhaustive comparative statics analysis of a general rate-of-return regulated, profit-maximizing model of the firm is carried out under a minimal set of assumptions. The resulting intrinsic comparative statics are contained in a positive semi-definite matrix. Each element of this matrix consists of a product of the A-J effect term and a Slutsky-like expression, thereby permitting the familiar interpretation of a compensated price change. The minimal set of assumptions allows a range of anomalous behavior that includes, inter alia, a reversal of the sign of the A-J effect and an increase in the use of an unregulated factor as a result of a compensated own-price increase. The implications of additional assumptions for the mathematical structure of the model and its economic consequences are discussed, and the equivalency relations among those assumptions are delineated. Throughout, mathematical results of the analysis are interpreted with a view to elucidating their intuitive economic significance.
Zeroes of the neutrino mass matrix

We assume there to be precisely three left-handed neutrino states whose Majorana masses are generated by an unspecified mechanism. Were CP is conserved, the symmetric neutrino mass matrix M would be real and all six of its distinct entries could be experimentally determined. But CP is not conserved so that M is likely to be complex. As a result, not all nine of its convention-independent real parameters can be determined without an appeal to theory. Thus we examine the possibility that a restricted class of neutrino mass matrices may suffice to describe current data, namely those complex symmetric matrices several of whose entries vanish. We find that there are seven acceptable textures with two independent zeroes, and we explore their contrasting phenomenological implications. Textures with more than two independent zeroes appear to be excluded by experiment.
Reconstruction of function fields

For k an algebraic closure of the finite field $$\mathbb{F}_p$$ , l prime distinct from p and X a surface over k, we prove that the field of rational functions k(X) can be recovered from the maximal pro-l-quotient $${\mathcal{G}}_{K}$$ of its absolute Galois group – in fact already from the second central descending series quotient of $${\mathcal{G}}_{K}$$ .
Noise, bifurcations, and modeling of interacting particle systems

We consider the stochastic patterns of a system of communicating, or coupled, self-propelled particles in the presence of noise and communication time delay. For sufficiently large environmental noise, there exists a transition between a translating state and a rotating state with stationary center of mass. Time delayed communication creates a bifurcation pattern dependent on the coupling amplitude between particles. Using a mean field model in the large number limit, we show how the complete bifurcation unfolds in the presence of communication delay and coupling amplitude. Relative to the center of mass, the patterns can then be described as transitions between translation, rotation about a stationary point, or a rotating swarm, where the center of mass undergoes a Hopf bifurcation from steady state to a limit cycle. Examples of some of the stochastic patterns will be given for large numbers of particles.
Modeling and simulation of C-E deep bowl pulverizer

A mathematical model of a deep bowl (RB) type C-E bowl pulverizer is developed. With practical applications in mind, the model is developed with compromised modeling accuracy and computational complexity. In this model, the internal structure of a pulverizer is divided into five zones. The grinding, pneumatic transport, and classification processes are considered in corresponding zones. Coal is differentiated into several size groups. Mass, temperature, and pressure variations are also taken into account based on physical principles. Simulations are also included to demonstrate the effectiveness of the model.
Domain adaptation for statistical classifiers

The most basic assumption used in statistical learning theory is that training data and test data are drawn from the same underlying distribution. Unfortunately, in many applications, the "in-domain" test data is drawn from a distribution that is related, but not identical, to the "out-of-domain" distribution of the training data. We consider the common case in which labeled out-of-domain data is plentiful, but labeled in-domain data is scarce. We introduce a statistical formulation of this problem in terms of a simple mixture model and present an instantiation of this framework to maximum entropy classifiers and their linear chain counterparts. We present efficient inference algorithms for this special case based on the technique of conditional expectation maximization. Our experimental results show that our approach leads to improved performance on three real world tasks on four different data sets from the natural language processing domain.
Low-dimensional models of a temporally evolving free shear layer

We develop low-dimensional models for the evolution of a free shear layer in a periodic domain. The goal is to obtain models simple enough to be analyzed using standard tools from dynamical systems theory, yet including enough of the physics to model nonlinear saturation and energy transfer between modes (e.g., pairing). Recently, experiments have suggested that high-frequency forcing of shear layers over open cavities may provide a mechanism for suppression of tones in cavities, and a long-term goal of this work is to study the dynamics of forced shear layers, to better understand these effects. In the present paper, 2D direct numerical simulations of a spatially periodic, temporally developing shear layer are performed. Low-dimensional models for these dynamics are obtained using a modified version of proper orthogonal decomposition/Galerkin projection, in which the basis functions can scale in space as the shear layer spreads. Equations are obtained for the rate of change of the shear layer thickness. When scaling is included in the shear flow dominated by k = 1 only, the first POD mode of wave number k = 1 captures 93% of the energy, which is impossible to obtain by regular POD analysis without scaling. For the flow dominated by both k = 1 and k = 2, when scaling is included, the first POD mode of wave number k = 1 and k = 2 together capture 95% of the total energy. Projection of incompressible Navier-Stokes equations to the first two POD modes of k = 1 gives a simple 2-mode model. If the projection is onto the first two POD modes of both k = 1 and k = 2, a more complex 4-mode model can be built to describe more complex flows. The 2-mode model can describe certain single-frequency features of the system, such as vortex roll-up, nonlinear saturation, and viscous damping. The 4-mode model can describe interactions between two frequencies (vortex merging) as well. The relation between the phase difference of the first (symmetric) and second (asymmetric) POD modes of the same wave number and the shear layer spreading rate can be clearly observed in both direct numerical simultions and model computations.
Who Plays the Numbers Games in the Middle of the Day

We analyse the increase in sales of Pick 3 and Pick 4 daily numbers lottery games and other Ohio Lottery games after Ohio introduced midday drawings for the Pick 3 and Pick 4 games in August 1999. The midday drawings increased Pick 3 sales by 5%, Pick 4 sales by 12%, and total lottery sales by 2% based on our analysis of a 36-month panel dataset of Ohio lottery sales by zip code. Midday drawings raise more revenue from the strongly regressive daily numbers games. However, the introduction of midday drawings does not change the negative income elasticities of demand for numbers games in an economically meaningful manner.
Real-Time Image Segmentation for Image-Guided Surgery

Image-guided surgery is an application for which high performance computing is increasingly becoming a critical technology. Advances in image-guided surgery techniques have made it possible to acquire images of a patient whilst the surgery is taking place, to align these images with high resolution 3D scans of the patient acquired preoperatively and to merge intraoperative images from multiple imaging modalities. The application of these technologies has now become a routine clinical procedure in some hospitals. However, as the type of procedures undertaken is expanded, it is becoming clear that the use of image fusion and linear registration technology alone has some limitations. We have developed a novel image segmentation algorithm that makes use of an individualized template of normal patient anatomy in order to compute the segmentation of intraoperative imaging data. Intraoperative image segmentation is highly data and compute intensive. In order to achieve accurate segmentation in a time frame compatible with surgical intervention, we have developed a parallel version of our segmentation algorithm, and implemented the algorithm on a symmetric multiprocessor architecture. We have studied the accuracy of the segmentation algorithm, and the scalability and bandwidth requirements of our parallel implementation.
Do private and portable web browsers leave incriminating evidence?: a forensic analysis of residual artifacts from private and portable web browsing sessions

The Internet is an essential tool for everyday tasks. Aside from common use, the option to browse the Internet privately is a desirable attribute. However, this can create a problem when private Internet sessions become hidden from computer forensic investigators in need of evidence. Our primary focus in this research is to discover residual artifacts from private and portable web browsing sessions. In addition, the artifacts must contain more than just file fragments and enough to establish an affirmative link between user and session. Certain aspects of this topic have triggered many questions, but there have never been enough authoritative answers to follow. As a result, we propose a new methodology for analyzing private and portable web browsing artifacts. Our research will serve to be a significant resource for law enforcement, computer forensic investigators, and the digital forensics research community.
Estimation of Excitation Energy of Diatomic Molecules in Expanding Nonequilibrium Flows

The energy contained in the highly excited vibrational and rotational states in a diatomic gas in a thermochemical nonequilibrium state during expansion is estimated. The population distribution of the vibrational and rotational states is assumed to be describable by a polynomial. The parameters in the polynomial are determined by invoking known physical constraints. The energy contained in the internal states in excess of that accounted for in the conventional method is calculated for N2, O2, NO, CO, and H2. The calculation is carried over a wide range of conditions, and the results are fitted with polynomials. The population distributions so determined agree with the theoretical and experimental results of others. A sample calculation made for a typical nozzle flow shows that the excess energy may reach 6% of the total enthalpy of the flow, and that the flow velocity may decrease by 3% due to this phenomenon. Nomenclature A = cross-sectional area of nozzle a{ =
Coherence analysis of iterative thresholding algorithms

There is a recent surge of interest in developing algorithms for finding sparse solutions of underdetermined systems of linear equations y = Φχ. In many applications, extremely large problem sizes are envisioned, with at least tens of thousands of equations and hundreds of thousands of unknowns. For such problem sizes, low computational complexity is paramount. The best studied l 1 minimization algorithm is not fast enough to fulfill this need. Iterative thresholding algorithms have been proposed to address this problem. In this paper we want to analyze three of these algorithms theoretically, and give sufficient conditions under which they recover the sparsest solution.
Wellness programs and means of getting employees to stay healthy: a response to Kristin Van Busum and Soeren Mattke.

This is a short writing in response to the “Financial Incentives: Only One Piece of the Workplace Wellness Puzzle” (1) by Kristin Van Busum and Soeren Mattke of the RAND Health Advisory Services, RAND Corporation, in Boston.
NHC–Cu-Catalyzed Addition of Propargylboron Reagents to Phosphinoylimines. Enantioselective Synthesis of Trimethylsilyl-Substituted Homoallenylamides and Application to the Synthesis of S-(−)-Cyclooroidin

A catalytic method for the efficient and enantioselective addition of a 1-trimethylsilyl-substituted allene moiety to phosphinoylimines is presented. Transformations are promoted by 5.0 mol % of a copper complex of an N-heterocyclic carbene in the presence of a propargylboron reagent that can be readily prepared in multigram quantities. Within 10 min of reaction, products are obtained in up to 91% yield, 98% allene (vs propargyl) selectivity, and 98:2 enantiomeric ratio. An assortment of aldimines serve as suitable substrates. The phosphinoyl and silyl groups can be removed efficiently and orthogonally. The silylallene moiety may be transformed to versatile derivatives that are difficult to access via nonsilylated allenes. The special features and utility of the approach are highlighted through a succinct enantioselective synthesis of marine alkaloid S-(−)-cyclooroidin.
How Happiness Affects Choice

Consumers want to be happy, and marketers are increasingly trying to appeal to consumers’ pursuit of happiness. However, the results of six studies reveal that what happiness means varies, and consumers’ choices reflect those differences. In some cases, happiness is defined as feeling excited, and in other cases, happiness is defined as feeling calm. The type of happiness pursued is determined by one’s temporal focus, such that individuals tend to choose more exciting options when focused on the future, and more calming options when focused on the present moment. These results suggest that the definition of happiness, and consumers’ resulting choices, are dynamic and malleable.
Information flow analysis of interactome networks.

Recent studies of cellular networks have revealed modular organizations of genes and proteins. For example, in interactome networks, a module refers to a group of interacting proteins that form molecular complexes and/or biochemical pathways and together mediate a biological process. However, it is still poorly understood how biological information is transmitted between different modules. We have developed information flow analysis, a new computational approach that identifies proteins central to the transmission of biological information throughout the network. In the information flow analysis, we represent an interactome network as an electrical circuit, where interactions are modeled as resistors and proteins as interconnecting junctions. Construing the propagation of biological signals as flow of electrical current, our method calculates an information flow score for every protein. Unlike previous metrics of network centrality such as degree or betweenness that only consider topological features, our approach incorporates confidence scores of protein–protein interactions and automatically considers all possible paths in a network when evaluating the importance of each protein. We apply our method to the interactome networks of Saccharomyces cerevisiae and Caenorhabditis elegans. We find that the likelihood of observing lethality and pleiotropy when a protein is eliminated is positively correlated with the protein's information flow score. Even among proteins of low degree or low betweenness, high information scores serve as a strong predictor of loss-of-function lethality or pleiotropy. The correlation between information flow scores and phenotypes supports our hypothesis that the proteins of high information flow reside in central positions in interactome networks. We also show that the ranks of information flow scores are more consistent than that of betweenness when a large amount of noisy data is added to an interactome. Finally, we combine gene expression data with interaction data in C. elegans and construct an interactome network for muscle-specific genes. We find that genes that rank high in terms of information flow in the muscle interactome network but not in the entire network tend to play important roles in muscle function. This framework for studying tissue-specific networks by the information flow model can be applied to other tissues and other organisms as well.
Catalytic reduction of dinitrogen under mild conditions.

Richard Schrock describes his work at MIT leading to abiological catalytic reduction of dinitrogen at ambient pressure and temperature with protons and electrons at a well-defined transition metal site.
FROM RIBBON CATEGORIES TO GENERALIZED YANG–BAXTER OPERATORS AND LINK INVARIANTS (AFTER KITAEV AND WANG)

We consider two approaches to isotopy invariants of oriented links: one from ribbon categories and the other from generalized Yang–Baxter (gYB) operators with appropriate enhancements. The gYB-operators we consider are obtained from so-called gYBE objects following a procedure of Kitaev and Wang. We show that the enhancement of these gYB-operators is canonically related to the twist structure in ribbon categories from which the operators are produced. If a gYB-operator is obtained from a ribbon category, it is reasonable to expect that two approaches would result in the same invariant. We prove that indeed the two link invariants are the same after normalizations. As examples, we study a new family of gYB-operators which is obtained from the ribbon fusion categories SO(N)2, where N is an odd integer. These operators are given by 8 × 8 matrices with the parameter N and the link invariants are specializations of the two-variable Kauffman polynomial invariant F.
In search of lost introns

Many fundamental questions concerning the emergence and subsequent evolution of eukaryotic exon–intron organization are still unsettled. Genome-scale comparative studies, which can shed light on crucial aspects of eukaryotic evolution, require adequate computational tools. We describe novel computational methods for studying spliceosomal intron evolution. Our goal is to give a reliable characterization of the dynamics of intron evolution. Our algorithmic innovations address the identification of orthologous introns, and the likelihood-based analysis of intron data. We discuss a compression method for the evaluation of the likelihood function, which is noteworthy for phylogenetic likelihood problems in general. We prove that after O(nl) preprocessing time, subsequent evaluations take O(nl/log l) time almost surely in the Yule–Harding random model of n-taxon phylogenies, where l is the input sequence length. We illustrate the practicality of our methods by compiling and analyzing a data set involving 18 eukaryotes, which is more than in any other study to date. The study yields the surprising result that ancestral eukaryotes were fairly intron-rich. For example, the bilaterian ancestor is estimated to have had more than 90% as many introns as vertebrates do now. Availability: The Java implementations of the algorithms are publicly available from the corresponding author's site http://www.iro.umontreal.ca/~csuros/introns/. Data are available on request. Contact: csuros@iro.umontreal.ca
The Roles of Small Telescopes in a Virtual Observatory Environment

The advent of the Virtual Observatory (VO) concept signals a paradigm shift in the way astronomy will be done in the era of information abundance and ubiquitous networking. Small telescopes will be playing a number of essential roles in this new research environment, probably contributing a major portion of all data taken in astronomy, both as surveying instruments, and as follow-up facilities. In this review we describe the VO concept and its background, and how small telescopes will fit in this emergent way of doing astronomy in the 21st century.
OBSERVATION OF THE TOP QUARK

Top-quark production is observed in collisions at at the Fermilab Tevatron. The CDF and DO collaborations observe signals consistent with to but inconsistent with the background prediction by 4.8σ (CDF) and 4.6σ (DO). Additional evidence for the top quark is provided by a peak in the reconstructed mass distribution. The kinematic properties of the excess events are consistent with the top-quark decay. The top-quark mass has been measured to be 176±8(stat.) ±10(sys.)GeV/c2 (CDF) and ±22(sys.)GeV/c2 (DO), and the -production cross section to be and 6.4±2.2 pb (DO).
American Higher Education in Transition

Abstract American higher education is in transition along many dimensions: tuition levels, faculty composition, expenditure allocation, pedagogy, technology, and more. During the last three decades, at private four-year academic institutions, undergraduate tuition levels increased each year on average by 3.5 percent more than the rate of inflation; the comparable increases for public four-year and public two-year institutions were 5.1 percent and 3.5 percent, respectively. Academic institutions have also changed how they allocate their resources. The percentage of faculty nationwide that is full-time has declined, and the vast majority of part-time faculty members do not have Ph.D.s. The share of institutional expenditures going to faculty salaries and benefits in both public and private institutions has fallen relative to the share going to nonfaculty uses like student services, academic support, and institutional support. There are changing modes of instruction, together with different uses of technolog...
The Ecological and Civil Mainsprings of Property: An Experimental Economic History of Whalers’ Rules of Capture

This article uses a laboratory experiment to probe the proposition that property emerges anarchically out of social custom. We test the hypothesis that whalers in the 18th and 19th centuries developed rules of conduct that minimized the sum of the transaction and production costs of capturing their prey, the primary implication being that different ecological conditions led to different rules of capture. Ceteris paribus, we find that simply imposing two different types of prey is insufficient to observe two different rules of capture. Another factor is essential, namely, as Samuel Pufendorf theorized over 300 years ago, that the members of
Toughening by Monoclinic Zirconia

The toughening induced by monoclinic ZrO2 in the absence of microcracking was investigated, using ZnO as the host material. Toughness levels Kc in excess of the host toughness KcM were achieved, attaining a peak toughness Kc/KcM∼1.7, at monoclinic ZrO2 volume concentrations 0.2. This toughening is attributed to crack/particle interactions, associated with the deflection and bowing of the crack by the residual strain field around the monoclinic ZrO2 particles.
Mottness collapse and T-linear resistivity in cuprate superconductors.

Central to the normal state of cuprate high-temperature superconductors is the collapse of the pseudo-gap, briefly reviewed here, at a critical point and the subsequent onset of the strange metal c...
Suppression of radio frequency interference at the distributor rotor gap

Generally, for a given spark gap length, lower breakdown voltage of the gap corresponds to a lower radio frequency interference (RFI) level. Mechanisms which lead to the reduction of breakdown voltage at the spark gap by two techniques are discussed. The first technique involves the addition of a pointed electrode near the cathode, while the second technique involves the presence of bulk dielectric material on the cathode surface near the gap. Practical distributor rotor designs based on these techniques for effective RFI control are described.
Adaptive filter design for estimation and detection of biological signals: an application to electroencephalography

An innovative technique for estimation and detection of alpha waves using adaptive filters is presented. In these analyses both Wiener transfer functions and non-Wiener transfer functions are used. Comparisons are made for different RMS signal-to-noise ratios. Simulations are done with class 1 filters where prior knowledge of all spectra estimates is assumed. These techniques are found to be very flexible in their application to other biological signals. >
The Importance of Relative Standards in ADHD Diagnoses: Evidence Based on Exact Birth Dates

This paper presents evidence that diagnoses of attention-deficit/hyperactivity disorder (ADHD) are driven largely by subjective comparisons across children in the same grade in school. Roughly 8.4 percent of children born in the month prior to their state's cutoff date for kindergarten eligibility - who typically become the youngest and most developmentally immature children within a grade - are diagnosed with ADHD, compared to 5.1 percent of children born in the month immediately afterward. A child's birth date relative to the eligibility cutoff also strongly influences teachers' assessments of whether the child exhibits ADHD symptoms but is only weakly associated with similarly measured parental assessments, suggesting that many diagnoses may be driven by teachers' perceptions of poor behavior among the youngest children in a classroom. These perceptions have long-lasting consequences: the youngest children in fifth and eighth grades are nearly twice as likely as their older classmates to regularly use stimulants prescribed to treat ADHD.
Tetrahydrofuran synthesis via free radical mediated addition of functionalized alkenes to aryl vinyl oxiranes

Abstract Tri- and tetrasubstituted tetrahydrofuran rings can be prepared by phenylthio radical mediated addition of functionalized alkenes across the carbon-carbon bond of aryl substituted vinyl oxiranes. Studies designed both to delineate the scope and limitations and elucidate the mechanistic course of this process are described.
From elevated freeways to surface boulevards: neighborhood and housing price impacts in San Francisco

Freeway “deconstruction” marks an abrupt shift in urban policy. Priorities are shifting away from designing cities to enhance mobility toward promoting livability. This paper investigates the neighborhood, traffic, and housing price impacts of replacing elevated freeways with surface boulevards in two corridors of San Francisco in California, USA: Embarcadero along the city's eastern waterfront and Central Freeway/Octavia Boulevard serving a predominantly residential neighborhood west of downtown. Using informant interviews, literature reviews, and statistical analyses, the research suggests that freeway conversions generally gentrifies neighborhoods, although policies like affordable housing mandates can temper displacement effects. Empirical evidence on residential sales transactions reveals that the disamenity effects of proximity to a freeway have for the most part given way to amenity benefits once roadways are converted to landscaped multiway boulevards. It is concluded that freeway‐to‐boulevard con...
Resistance in Superconductors

In this pedagogical review, we discuss how electrical resistance can arise in superconductors. Starting with the idea of the superconducting order parameter as a condensate wave function, we introduce vortices as topological excitations with quantized phase winding, and we show how phase slips occur when vortices cross the sample. Superconductors exhibit non-zero electrical resistance under circumstances where phase slips occur at a finite rate. For one-dimensional superconductors or Josephson junctions, phase slips can occur at isolated points in space-time. Phase slip rates may be controlled by thermal activation over a free-energy barrier, or in some circumstances, at low temperatures, by quantum tunneling through a barrier. We present an overview of several phenomena involving vortices that have direct implications for the electrical resistance of superconductors, including the Berezinskii-Kosterlitz-Thouless transition for vortex-proliferation in thin films, and the effects of vortex pinning in bulk type II superconductors on the nonlinear resistivity of these materials in an applied magnetic field. We discuss how quantum fluctuations can cause phase slips and review the non-trivial role of dissipation on such fluctuations. We present a basic picture of the superconductor-to-insulator quantum phase transitions in films, wires, and Josephson junctions. We point out related problems in superfluid helium films and systems of ultra-cold trapped atoms. While our emphasis is on theoretical concepts, we also briefly describe experimental results, and we underline some of the open questions.
Elevated methane concentrations in trees of an upland forest

[1] There is intense debate about whether terrestrial vegetation contributes substantially to global methane emissions. Although trees may act as a conduit for methane release from soils to atmosphere, the debate centers on whether vegetation directly produces methane by an uncharacterized, abiotic mechanism. A second mechanism of direct methane production in plants occurs when methanogens – microorganisms in the domain Archaea – colonize the wood of living trees. In the debate this biotic mechanism has largely been ignored, yet conditions that promote anaerobic activity in living wood, and hence potentially methane production, are prevalent across forests. We find average, growing season, trunk-gas methane concentrations >15,000μL·L−1in common, temperate-forest species. In upland habitat (where soils are not a significant methane source), concentrations are 2.3-times greater than in lowland areas, and wood cores produce methane in anaerobic, lab-assays. Emission rate estimates from our upland site are 52 ± 9.5 ng CH4 m−2 s−1; rates that are of a similar magnitude to the soil methane sink in temperate forest, and equivalent in global warming potential to ∼18% of the carbon likely sequestered by this forest. Microbial infection of one of the largest, biogenic sinks for carbon dioxide, living trees, might result in substantial, biogenic production of methane.
Vehicle headway monitoring & control for EU directive compliance

The Roads Tunnel Safety Regulations 2007 require that traffic [in a TERN ] tunnel maintain a travel time gap of 2 seconds; or 4 seconds for a HGV. These regulations also require the Administrative Authority for the Tunnel to ensure that the procedure for that tunnel's immediate closure in the event of an emergency is established. Throughout Europe this is commonly achieved by installing Traffic Signals at the tunnel entry portal. Traffic congestion in a road tunnel can significantly increase the probability of occurrence of a major incident - many tunnel operators seek to avoid congestion from occurring in their tunnels. This paper describes a system which integrates a number of different existing technologies to provide a "Tunnel Occupancy Manager". It is achieved by the application of the existing principles and technology to dynamically manage tunnel traffic flows. In normal operation, the system employs ANPR cameras to monitor the speed of and headway between vehicles approaching a road tunnel. If a vehicle is identified as travelling too close its number plate could be displayed on a VMS displaying the legend "VEHICLE REG "AB57 XYZ" KEEP YOUR DISTANCE". Similarly, enforcement proceedings could be initiated. This forms a “Traffic Calming” zone on the approaches to the tunnel where traffic speed and vehicle headway are regulated. When it appears that congestion is likely to occur in the tunnel (as monitored at the exit of the tunnel in a “Congestion Monitoring zone”), the Tunnel Occupancy Manager would start to "meter" traffic through the tunnel by firstly operating advanced warning signs and then modulating the switching frequency of traffic lights located near the entrance of the tunnel via a sophisticated control algorithm. If the flow rate away from the tunnel is less than the flow r
Linear-time encodable and decodable error-correcting codes

We present a new class of asymptotically good, linear error-correcting codes. These codes can be both encoded and decoded in linear time. They can also be encoded by logarithmic-depth circuits of linear size and decoded by logarithmic depth circuits of size O(nlogn). We present both randomized and explicit constructions of these codes.
The Landmark Selection Method for Multiple Output Prediction

Conditional modeling x → y is a central problem in machine learning. A substantial research effort is devoted to such modeling when x is high dimensional. We consider, instead, the case of a high dimensional y, where x is either low dimensional or high dimensional. Our approach is based on selecting a small subset yL of the dimensions of y, and proceed by modeling (i) x → yL and (ii) yL → y. Composing these two models, we obtain a conditional model x → y that possesses convenient statistical properties. Multilabel classification and multivariate regression experiments on several datasets show that this method outperforms the one vs. all approach as well as several sophisticated multiple output prediction methods.
A scheme for finding the front boundary of an interplanetary magnetic cloud

Abstract. We develop a scheme for finding a "refined" front boundary-time ( t B *) of an interplanetary magnetic cloud (MC) based on criteria that depend on the possible existence of any one or more of four specific solar wind features. The features that the program looks for, within ±2 h (i.e., the initial uncertainty interval) of a preliminarily estimated front boundary time, are: (1) a sufficiently large directional discontinuity in the interplanetary magnetic field (IMF), (2) a significant proton plasma beta (β P ) drop, (3) a significant proton temperature drop, and (4) a marked increase in the IMF's intensity. Also we examine to see if the "MC-side" of the boundary has a MC-like value of β P . The scheme was tested using 5, 10, 15, and 20 min averages of the relevant physical quantities from WIND data, in order to find the optimum average to use. The 5 min average, initially based on analysis of N =26 carefully chosen MCs, turned out to be marginally the best average to use for our purposes. Other criteria, besides the four described above, such as the existence of a magnetic hole, plasma speed change, and/or field fluctuation level change, were examined and dismissed as not reliable enough, or usually associated with physical quantities that change too slowly around the boundary to be useful. The preliminarily estimated front boundary time, t B , and its initial ±2-h uncertainty interval are determined by either an automatic MC identification scheme or by visual inspection. The boundary-scheme was developed specifically for aiding in forecasting the strength and timing of a geomagnetic storm due to the passage of a MC in real-time, but can be used in post ground-data collection for imposing consistency when choosing front boundaries of MCs. This scheme has been extensively tested, first using 81 bona fide MCs, collected over about 8.6 years of WIND data (at 1 AU), and also by using 122 MC-like structures as defined by Lepping et al. (2005) over about the same period. Final statistical testing of the 81 MCs to see how close the refined boundary-time t B * lies with respect to a preliminary time t B (VI) was carried out, i.e., to find Δ t 1 =( t B *– t B (VI)), for the full set of MCs, where t B (VI) is usually a very accurate time previously determined from visual inspection, This testing showed that 59 Δ t 1 s (i.e., 73%) lie within ±30 min, 71 Δ t 1 s (i.e., 88%) lie within ±45 min, and only 5 cases lie outside a |Δ t 1 | of 1.0 h, which is only 6% of the full 81, and these 6% would be considered unsatisfactory. Since MC parameter fitting is usually done on the basis of 30 or 60 min averages, these results seem quite satisfactory. The program for this front boundary estimation scheme is located at the Website: http://wind.nasa.gov/mc/boundary.php .
Identification of multivariable stochastic linear systems via polyspectral analysis given noisy input-output time-domain data

The paper considers the problem of identification of unknown parameters of multivariable, linear "errors-invariables" models. Attention is focused on frequency-domain approaches where the integrated polyspectrum (bispectrum or trispectrum) of the input and the integrated cross-polyspectrum, respectively, of the given time-domain input-output data are exploited. Two new classes of parametric frequency-domain approaches are proposed and analyzed. An integrated polyspectrum-based persistence of excitation condition on system input is defined. Both classes of the parameter estimators are shown to be strongly consistent in any measurement noise sequences with vanishing bispectra when integrated bispectrum-based approaches are used. The proposed parameter estimators are shown to be strongly consistent in Gaussian measurement noise when integrated trispectrum-based approaches are used. The input to the system need not be a linear process but must have nonvanishing bispectrum or trispectrum.
African Small and Medium Enterprises, Networks, and Manufacturing Performance

This paper examines the role of private support institutions in determining small and medium enterprise (SME) growth and performance in Sub-Saharan Africa (SSA). It finds that SMEs in SSA get around market failures and lack of formal institutions by creating private governance systems in the form of long-term business relationships and tight, ethnically-based, business networks. There are important links between these informal governance institutions and SME performance. Networks raise the performance of “insiders” and, in the sparse business environments of the SSA region, have attendant negative consequences for market participation of “outsiders,” such as indigenous-African SMEs. This is indicated through the determinants of access to supplier credit. Policy interventions will be needed to improve the platform for relationbased governance mechanisms and to address the exclusionary effects of tight networks.
The Effect of Silicon Powder Characteristics on the Combustion of Silicon/Teflon/Viton Nanoenergetics

Due to its thin passivation layer, potentially good aging characteristics, and ease of surface functionalization nanoscale silicon (Si) may offer some advantages over nanoaluminum as a reactive fuel in nanoenergetic compositions, particularly with fluorine-based oxidizers. Currently, Si nanopowder can be quite expensive and the quality of commercial powders has been found to vary drastically. As a result limited efforts have focused on the role of specific surface area, active content, morphology, and dominant particle size of the powder have on the combustion performance. In this work we report the effect of such characteristics on the combustion of silicon (Si)/polytetrafluoroethylene (Teflon)/FC-2175 (Viton) (SiTV) nanoenergetics. A cost effective combustion synthesis route, salt assisted combustion synthesis, was used to produce several Si powders and these were directly compared to commercial nanoscale Si powders. Reactive mixtures of SiTV were burned at atmospheric conditions and burning rates, combustion temperatures, spectral intensities, and effective plume emissivities were measured. Measured combustion temperatures ranged from 1664 to 2380 K and were limited by Si powder active content. This was found to drive plume emissivity and maximum spectral intensity, which had values ranging from 0.10 to 0.55 for effective plume emissivity and 17.6 to 48.1 kW m−2 sr−1 μm−1 for maximum spectral intensity. Burning rates ranged from 0.7 to 3.4 mm s−1 and were found to be dependent on the dominant particle size of the powder. Powders synthesized with salt assisted combustion resulted in comparable burning rate, plume emissivity and maximum spectral intensity to porous Si powder (Vesta Ceramics).
Iron(II) spin crossover films on Au(111): scanning probe microscopy and photoelectron spectroscopy

The growth of films of [H2B(pz)2]Fe(II)(bpy) on Au(111) is characterized from the bilayer film to multilayer film regime. Scanning tunneling microscopy shows a transition from a well-ordered, uniform bilayer film to a poorly-ordered film at larger thicknesses. Previous local tunneling spectroscopy and conductance mapping in bilayer films permit the identification of coexisting molecular spin-states at all temperatures. New ultraviolet photoelectron spectroscopy is consistent with this picture and in agreement with the density of states calculated by density functional theory. In thicker films with a polycrystalline morphology, evidence for a more bulk-like change in spin composition as a function of temperature is obtained by observing the reduction in intensity of Fe 2p core level satellites in X-ray photoelectron spectra.
Trade and prices with heterogeneous firms

This paper estimates a heterogeneous firms trade model using disaggregate data on export values and prices. Prices contain information about differences in product quality across firms and countries that helps identify key mechanisms in the model. Examining withincountry variation in export prices across destination markets, I find that prices behave in a manner inconsistent with the benchmark model that ignores product quality differences across firms. In doing so, I demonstrate that export prices in most sectors are consistent with a model in which high productivity firms choose to produce high quality goods and charge high prices. Using model estimates, I also quantify the role of endogenous nontradability in accounting for variation in prices and trade flows, and construct an index of cross-country quality and variety within sectors.
Households or locations ? cities, catchment areas and prosperity in India

Policy makers in developing countries, including India, are increasingly sensitive to the links between spatial transformation and economic development. However, the empirical knowledge available on those links is most often insufficient to guide policy decisions. There is no shortage of case studies on urban agglomerations of different sorts, or of benchmarking exercises for states and districts, but more systematic evidence is scarce. To help address this gap, this paper combines insights from poverty analysis and urban economics, and develops a methodology to assess spatial performance with a high degree of granularity. This methodology is applied to India, where individual household survey records are mapped to “places” (both rural and urban) below the district level. The analysis disentangles the contributions household characteristics and locations make to labor earnings, proxied by nominal household expenditure per capita. The paper shows that one-third of the variation in predicted labor earnings is explained by the locations where households reside and by the interaction between these locations and household characteristics such as education. In parallel, this methodology provides a workable metric to describe spatial productivity patterns across India. The paper shows that there is a gradation of spatial performance across places, rather than a clear rural-urban divide. It also finds that distance matters: places with higher productivity are close to each other, but some spread their prosperity over much broader areas than others. Using the spatial distribution of this metric across India, the paper further classifies places at below-district level into four tiers: top locations, their catchment areas, average locations, and bottom locations. The analysis finds that some small cities are among the top locations, while some large cities are not. It also finds that top locations and their catchment areas include many high-performing rural places, and are not necessarily more unequal than average locations. Preliminary analysis reveals that these top locations and their catchment areas display characteristics that are generally believed to drive agglomeration economies and contribute to faster productivity growth.
Observations of NBTI-induced atomic-scale defects

A combination of MOSFET gate-controlled diode measurements and a very sensitive electron spin resonance technique called spin-dependent recombination was utilized to observe and identify defect centers generated by a negative bias temperature stress in fully processed SiO 2-based pMOSFETs. In SiO2 devices, the defects include two Si/SiO2 interface silicon dangling bond centers (Pb0 and Pb1) and may also include an oxide silicon dangling bond center (E'). The observations indicate that both P b0 and Pb1 defects play major roles in these SiO 2-based devices and suggest that E' centers could play an important role
Nonstationary Ascent Wind Analysis

A statistical approach for computing launch vehicle response to inflight winds is presented. In the response analysis the zonal component of the ascent wind velocity is modeled as a nonstationary random process. Model parameters are computed by processing available measured wind data. Pertinent pitch plane response statistics are computed and their value in constructing fatigue load spectra for a reusable launch vehicle is demonstrated. A method for using the response statistics to estimate structural reliability is also discussed. The accuracy and the cost saving potential of the probabilistic structural dynamics approach are assessed by performing comparisons with digital simulation results.