cssi/SciSciGPT-SciSciNet huggingface dataset:
Visualizing brain rhythms and synchrony

Patterns of synchronized brain activity have been widely observed in EEGs and multi-electrode recordings, and much study has been devoted to understanding their role in brain function. We introduce the problem of visualization of synchronized behavior and propose visualization techniques for assessing temporal and spatial patterns of synchronization from data. We discuss spike rate plots, activity succession diagrams, space-time activity band visualization, and low-dimensional projections as methods for identifying synchronized behavior in populations of neurons and for detecting the possibly short-lived neuronal assemblies that produced them. We use wavelets conjunction with these visualization techniques to extract the frequency and temporal localization of synchronized behavior. Most of these techniques can be streamed, making them suitable for analyzing long-running experimental recordings as well as the output of simulation models.
A framework for quantitative analysis of cascades on networks

How does information flow in online social networks? How does the structure and size of the information cascade evolve in time? How can we efficiently mine the information contained in cascade dynamics? We approach these questions empirically and present an efficient and scalable mathematical framework for quantitative analysis of cascades on networks. We define a cascade generating function that captures the details of the microscopic dynamics of the cascades. We show that this function can also be used to compute the macroscopic properties of cascades, such as their size, spread, diameter, number of paths, and average path length. We present an algorithm to efficiently compute cascade generating function and demonstrate that while significantly compressing information within a cascade, it nevertheless allows us to accurately reconstruct its structure. We use this framework to study information dynamics on the social network of Digg. Digg allows users to post and vote on stories, and easily see the stories that friends have voted on. As a story spreads on Digg through voting, it generates cascades. We extract cascades of more than 3,500 Digg stories and calculate their macroscopic and microscopic properties. We identify several trends in cascade dynamics: spreading via chaining, branching and community. We discuss how these affect the spread of the story through the Digg social network. Our computational framework is general and offers a practical solution to quantitative analysis of the microscopic structure of even very large cascades.
Automatic Grammar Induction and Parsing Free Text: A Transformation-Based Approach

In this paper we describe a new technique for parsing free text: a transformational grammar1 is automatically learned that is capable of accurately parsing text into binary-branching syntactic trees with nonterminals unlabelled. The algorithm works by beginning in a very naive state of knowledge about phrase structure. By repeatedly comparing the results of bracketing in the current state to proper bracketing provided in the training corpus, the system learns a set of simple structural transformations that can be applied to reduce error. After describing the algorithm, we present results and compare these results to other recent results in automatic grammar induction.
Application of an Artificial Neural Network as a Flight Test Data Estimator

During a flight test program, certain instrumented parameters are subject to degradation due to wear and tear. Over the course of a flight test program, data from several flights will be lost due to undetected instrumentation faults. The application of artificial neural networks as flight test data estimators has been proposed with the intention of reducing the aforementioned cost and wasted test flights. Several network topologies have been studied. A simulation program has been used to identify the appropriate network topology for this task. It is shown that a single network is not capable of predicting all of the correct values of the suspect parameters based solely on the information received from the reliable instruments. However, it is shown that a collection of smaller networks can succeed in this task, with each network predicting one suspect parameter. Limited training and test results based on simulation-generated data are presented. Actual flight test data from a typical business jet have been used to verify this concept and these results are presented as well. It is demonstrated that in most cases these networks are capable of predicting the measured parameter outputs with sufficient accuracy to enable identification of instrumentation system degradation.
Untraceable electronic mail, return addresses, and digital pseudonyms

A technique based on public key cryptography is presented that allows an electronic mail system to hide who a participant communicates with as well as the content of the communication - in spite of an unsecured underlying telecommunication system. The technique does not require a universally trusted authority. One correspondent can remain anonymous to a second, while allowing the second to respond via an untraceable return address. The technique can also be used to form rosters of untraceable digital pseudonyms from selected applications. Applicants retain the exclusive ability to form digital signatures corresponding to their pseudonyms. Elections in which any interested party can verify that the ballots have been properly counted are possible if anonymously mailed ballots are signed with pseudonyms from a roster of registered voters. Another use allows an individual to correspond with a record-keeping organization under a unique pseudonym, which appears in a roster of acceptable clients.
Spacecraft Protective Structures Design Optimization

The optimization of spacecraft protective structures design to defeat hypervelocity impacts of meteoroids and space debris is presented. A space debris environment model is incorporated into an overall optimization methodology employing engineering models developed to predict protective structures design requirements for hypervelocity impact loads. Several nonlinear optimization techniques are used to generate design parametrics based on environment, mission, and configuration variables for the Space Station Core Module Configuration. Results indicate that careful consideration of the spacecraft structural configuration and materials can partially offset the design consequences of dramatic increases in the orbital space debris environment. Furthermore, the use of nonlinear optimization techniques coupled with hypervelocity impact engineering models can provide significant design tradeoff insight through the use of parametric analyses.
Computing exponential moments of the discrete maximum of a Lévy process and lookback options

We present a fast and accurate method to compute exponential moments of the discretely observed maximum of a Levy process. The method involves a sequential evaluation of Hilbert transforms of expressions involving the characteristic function of the (Esscher-transformed) Levy process. It can be discretized with exponentially decaying errors of the form O(exp (−aM b )) for some a,b>0, where M is the number of discrete points used to compute the Hilbert transform. The discrete approximation can be efficiently implemented using the Toeplitz matrix–vector multiplication algorithm based on the fast Fourier transform, with total computational cost of O(NMlog (M)), where N is the number of observations of the maximum. The method is applied to the valuation of European-style discretely monitored floating strike, fixed strike, forward start and partial lookback options (both newly written and seasoned) in exponential Levy models.
A recursive method for finding revolute-jointed manipulator singularities

A geometric application of screw theory is used to develop a recursive algorithm for computing all singular configurations of revolute-jointed manipulators with arbitrary link geometries and an arbitrary number of joints. The depth of the recursion is linear in the number of joints, n, while the computational burden is proportional to 2 n−2 . This method does not require explicit construction of the Jacobian matrix elements or a determinant operation. The method is also robust with respect to the bifurcations that occur for industrial robot geometries. Further, the screw axis of the singular motion is determined at no additional cost
Using Microsimulation Feedback For Trip Adaptation For Realistic Traffic In Dallas

This paper presents a day-to-day re-routing relaxation approach for traffic simulations. Starting from an initial planset for the routes, the route- based microsimulation is executed. The result of the microsimulation is fed into a re-router, which re-routes a certain percentage of all trips. This approach makes the traffic patterns in the microsimulation much more reasonable. Further, it is shown that the method described in this paper can lead to strong oscillations in the solutions.
2-(Diethylamino)ethanethiol, a New Reagent for the Odorless Deprotection of Aromatic Methyl Ethers

A new reagent for the deprotection of aromatic methyl ethers, 2-(diethylamino)ethanethiol, is reported. This compound, commercially available as its HCl salt, affords the corresponding phenols in good to excellent yields on a wide variety of substrates. A clear advantage of this method over the use of more common thiols, such as ethanethiol, is the easy extraction of both the deprotecting reagent and the byproduct 2-(diethylamino)ethyl methyl sulfide into the aqueous phase by quenching with dilute acid, which allows an essentially odorless workup.
Global stability of congestion controllers for the Internet

We consider a single link accessed by a single source which responds to congestion signals from the network. The design of controllers for such sources in the presence of feedback delay has received much attention recently. Here, we present conditions for the global, asymptotic stability and semiglobal exponential stability of congestion controllers. These conditions are natural extensions of conditions obtained through linearized analysis of such systems. Our result on exponential stability provides the missing link in the proof of how one obtains a single deterministic congestion control equation from a system with many congestion-controlled sources and random disturbances. Using numerical examples, we compare the conditions on the congestion-control parameters obtained using local and global stability analysis.
Non-Gaussian Target Detection in Sonar Imagery Using the Multivariate Laplace Distribution

This paper introduces a new non-Gaussian detection method for complex-valued synthetic aperture sonar (SAS) imagery. The detection method is based on a multivariate extension of the Laplace distribution derived using a scale mixture of Gaussian distributions. A goodness-of-fit test in the form of a likelihood ratio is then conducted on a sonar imagery data set consisting of high-frequency (HF) and broadband (BB) images coregistered over the same region on the seafloor showing the proposed model's applicability in sonar imagery. Detection based on testing the equality of parameters from two populations is then implemented on a database containing actual SAS images of the seafloor with synthetically generated targets inserted into the images and compared to a similar non-Gaussian technique. Detection performance in this paper is given in terms of receiver-operator characteristic (ROC) curve attributes, probability of detection, and average false alarm rate.
On the Philosophy of Group Decision Methods II: Alternatives to Majority Rule

In this companion piece to ‘On the Philosophy of Group Decision Methods I: The Non-Obviousness of Majority Rule’, we take a closer look at some competitors of majority rule. This exploration supplements the conclusions of the other piece, as well as offers a further-reaching introduction to some of the challenges that this field currently poses to philosophers.
Design of Vibration Absorbers for Step Motions and Step Disturbances

Mechanical systems with flexible dynamics often suffer from vibration induced by changes in the reference command or from external disturbances. The technique of adding a vibration absorber has proven useful at eliminating vibrations from external disturbances and rotational imbalances. Traditionally, vibration absorbers have been designed for systems subject to sinusoidal or random excitations. Here the applicability of vibration absorbers to systems with steplike changes in the reference command or similar disturbances is studied. This type of motion is more common in robotic applications. Here absorbers are designed using two methods; the first technique uses a weighting on peak overshoot and settling time to allow tradeoffs between the two performance criteria. The second simpler method utilizes an eigenvalue technique to predict the time constant. Both of these techniques provide the possibility of significant improvement in settling time. The performance of this absorber design strategies is compared with previously proposed vibration absorbers and experimental results verify its utility. @DOI: 10.1115/1.1825441#
Spontaneous violation of Lorentz and CPT symmetry

The standard model as well as many of its modern day extensions preserves Lorentz and CPT symmetry. In fact, symmetry under the Lorentz group is a fundamental assumption of virtually any fundamental theory used to describe elementary particle physics. Under very mild assumptions, the postulates of a point particle theory that preserves Lorentz invariance imply that CPT is also preserved [1]. In this proceedings, I will discuss the construction of quantum field theories that break Lorentz and CPT symmetry. There are both experimental and theoretical motivations to develop such theories. Many sensitive experimental tests of Lorentz and CPT symmetry have been performed. For example, high precision tests involving atomic systems [2, 3], clock comparisons [4, 5], and neutral meson oscillations [6, 7] provide stringent tests of Lorentz and CPT symmetry. Recently, a pendulum with a net macroscopic spin angular momentum has been constructed and used to investigate spin-dependent Lorentz and CPT violation [8]. In the past, such experiments have placed bounds on phenomenological parameters that lack any clear connection with the microscopic physics of the standard model. One motivation of constructing a theory in the context of the standard model that allows for Lorentz and CPT violation is the desire to have a single theory within the context of conventional quantum field theory that could relate various experiments and be used to motivate future investigations. This begs the question as to how such effects might arise naturally within the current framework of quantum field theory. The main idea is that miniscule lowenergy remnant effects that violate fundamental symmetries may arise in theories underlying the standard model. One example is string theory in which nontrivial structure of the vacuum solutions may induce observable Lorentz and CPT violations [9, 10, 11]. Rather than attempting a construction based directly on a specific underlying model, such as string theory, we proceed using the generic mechanism of spontaneous symmetry violation to implement the breaking. Terms involving standard model fields that violate Lorentz and CPT symmetry are assumed to arise from a
Deterministic greedy routing with guaranteed delivery in 3D wireless sensor networks

With both computational complexity and storage space bounded by a small constant, greedy routing is recognized as an appealing approach to support scalable routing in wireless sensor networks. However, significant challenges have been encountered in extending greedy routing from 2D to 3D space. In this research we develop decentralized solutions to achieve greedy routing in 3D sensor networks. Our proposed approach is based on a unit tetrahedron cell (UTC) mesh structure. We propose a distributed algorithm to realize volumetric harmonic mapping of the UTC mesh under spherical boundary condition. It is a one-to-one map that yields virtual coordinates for each node in the network. Since a boundary has been mapped to a sphere, node-based greedy routing is always successful thereon. At the same time, we exploit the UTC mesh to develop a face-based greedy routing algorithm, and prove its success at internal nodes. To deliver a data packet to its destination, face-based and node-based greedy routing algorithms are employed alternately at internal and boundary UTCs, respectively. As far as we know, this is the first work that realizes truly deterministic greedy routing with constant-bounded storage and computation in 3D wireless sensor networks.
A new quantity for studies of dijet azimuthal decorrelations

We introduce a new measurable quantity, R��, for studies of the rapidity and transverse momentum dependence of dijet azimuthal decorrelations in hadron-hadron colli- sions. In pQCD, R�� is computed as a ratio of three-jet and dijet cross sections in which the parton distribution functions cancel to a large extent. At the leading order, R�� is propor- tional tos, and the transverse momentum dependence of R�� can therefore be exploited to determines. We compute the NLO pQCD theory predictions and non-perturbative corrections for R�� at the LHC and the Tevatron and investigate the corresponding uncer- tainties. From this, we estimate the theory uncertainties fors determinations based on R�� at both colliders. The potential of R�� measurements for tuning Monte Carlo event generators is also demonstrated.
Outsourcing under Imperfect Protection of Intellectual Property

The paper examines possible reasons behind expanded outsourcing by modeling outsourcing decisions when intellectual property rights are imperfectly protected. Firms in the North develop higher quality levels of existing products and then decide whether to shift some stages of production to the South. Production in the South lowers costs but entails risk of imitation by Southern firms. In this setting, a lower risk of imitation or larger labor supplies can cause increased outsourcing, a higher rate of innovation, and a lower Northern relative wage. Damage due to lower incomes can be offset by gains in terms of better quality products.
Ethics and Investment Management: True Reform

What happened to ethical behavior in the era of the dot-com, the bubble, Enron, and WorldCom? We were not involved in close ethical calls in these cases. The lapses were great, the conflicts many, and the cost, in terms of investor trust, nearly unspeakable. Each time scandals occur, market reforms result, but the pattern is that, despite their extensive nature, the reforms do not bring us an insurance policy against misconduct. True reform lies not in statutory or codified detail. Rather, true reform comes from a strong moral compass that is applied by leaders who demonstrate ethical courage. True reform requires a focus on doing more than the law requires and less than the law allows.
Guarding galleries and terrains

Let P be a polygon with n vertices. We say that two points of P see each other if the line segment connecting them lies inside (the closure of) P. In this paper we present efficient approximation algorithms for finding the smallest set G of points of P so that each point of P is seen by at least one point of G, and the points of G are constrained to be belong to the set of vertices of an arbitrarily dense grind. We also present similar algorithms for terrains and polygons with holes.
PROGRESS IN FOUR-DIMENSIONAL LATTICE SUPERSYMMETRY

We are entering an era where a number of large-scale lattice simulations of four-dimensional supersymmetric theories are under way. Moreover, proposals for how to approach such studies continue to progress. One particular line of research in this direction is described here. General actions for super-QCD, including counterterms required on the lattice, are given. We obtain the number of fine-tunings that is required, once gauge and flavor symmetries are accounted for, provided Ginsparg–Wilson fermions are used for the gauginos. We also review and extend our recent work on lattice formulations of super-Yang–Mills and super-Yang–Mills that exploit Ginsparg–Wilson fermions.
Effective Risk Communication for Android Apps

The popularity and advanced functionality of mobile devices has made them attractive targets for malicious and intrusive applications (apps). Although strong security measures are in place for most mobile systems, the area where these systems often fail is the reliance on the user to make decisions that impact the security of a device. As our prime example, Android relies on users to understand the permissions that an app is requesting and to base the installation decision on the list of permissions. Previous research has shown that this reliance on users is ineffective, as most users do not understand or consider the permission information. We propose a solution that leverages a method to assign a risk score to each app and display a summary of that information to users. Results from four experiments are reported in which we examine the effects of introducing summary risk information and how best to convey such information to a user. Our results show that the inclusion of risk-score information has significant positive effects in the selection process and can also lead to more curiosity about security-related information.
SENSITIVITY REDUCTION OVER A FREQUENCY BAND

The problem of reducing the sensitivity of a possibly infinite-dimensional linear single-input single-output system over a finite frequency interval by feedback is considered. Specifically, the following are proven: (i) if one wants to bound the overall sensitivity, the existence of a non-trivial inner part inhibits the reduction of the sensitivity over the interval; (ii) in a system that is continuous and has at most countably many zeros on the imaginary axis, one can reduce the sensitivity over an interval to be arbitrarily small, while the overall sensitivity is kept bounded if and only if the system is outer and has no zeros on the interval. These extend results for rational transfer functions.
A middleware service for secure group communication in mobile ad hoc networks

Secure group communication (SGC) is required in many applications using mobile ad hoc networks (MANETs). Due to the mobility and limited resources of mobile devices used by group members, secure groups in a MANET may be required to be set up and maintained dynamically, and applications requiring SGC may request to change the secure groups according to network and application status. In this paper, a secure group model is presented to describe common characteristics of secure groups based on hierarchical authentication relations among the members in each secure group. Based on this model, a middleware service for SGC is developed to set up and maintain secure groups automatically and support development and runtime of applications using SGC in MANETs. This middleware service is implemented in a context-sensitive middleware RCSM.
Generating effective symmetry-breaking predicates for search problems

Consider the problem of testing for existence of an n-node graph G satisfying some condition P, expressed as a Boolean constraint among the nxn Boolean entries of the adjacency matrix M. This problem reduces to satisfiability of P(M). If P is preserved by isomorphism, P(M) is satisfiable iff P(M)@?SB(M) is satisfiable, where SB(M) is a symmetry-breaking predicate-a predicate satisfied by at least one matrix M in each isomorphism class. P(M)@?SB(M) is more constrained than P(M), so it is solved faster by backtracking than P(M)-especially if SB(M) rules out most matrices in each isomorphism class. This method, proposed by Crawford et al., applies not just to graphs but to testing existence of a combinatorial object satisfying any property that respects isomorphism, as long as the property can be compactly specified as a Boolean constraint on the object's binary representation. We present methods for generating symmetry-breaking predicates for several classes of combinatorial objects: acyclic digraphs, permutations, functions, and arbitrary-arity relations (direct products). We define a uniform optimality measure for symmetry-breaking predicates, and evaluate our constraints according to this measure. Results indicate that these constraints are either optimal or near-optimal for their respective classes of objects.
Trade flows and trade disputes

This paper introduces a new data set and establishes a set of basic facts and patterns regarding the trade that countries fight about under World Trade Organization (WTO) dispute settlement. The paper characterizes the scope of products, as well as the levels of and changes to the trade values, market shares, volumes, and prices for those goods that eventually become subject to WTO litigation. The first result is striking heterogeneity in the level of market access at stake across disputes: for example, 14 percent of cases over disputed import products feature bilateral trade that is less than $1 million per year and another 15 percent feature bilateral trade that is more than $1 billion per year. Nevertheless, some strong patterns emerge from a more detailed examination of the data. Both high- and low-income complainants tend to suffer important losses in foreign market access in the products that ultimately become subject to dispute. Furthermore, although the respondent's imposition of an allegedly WTO-inconsistent policy is associated with reductions, on average, in trade values, volumes, and exporter-received prices, there is some evidence of differences in the size of these changes across the different types of policies under dispute and the potential exporter country litigants. Finally, these different types of policies under dispute can have dissimilar trade effects for the complainant relative to other (non-complainant) exporters of the disputed product and this is likely to affect the litigation allegiance of third countries.
Handling uncertainty due to the delay between complex sensing and manipulation in an industrial workcell

In this paper, we propose a generic method to model the dynamic intercept and manipulation capability of vision-based industrial robot systems. In order to verify the method, we present experiments using our industrial workcell prototype to dynamically intercept and manipulate semi-randomly moving objects.
Report from the Second International Workshop on Software Engineering for Computational Science and Engineering (SE-CSE 09)

Motivated by the general lack of interaction between software engineering researchers and computational scientists/engineers, a the Second International Workshop onon Software Engineering for Computational Science and Engineering (SE-CSE09) was held during the 2009 International Conference on Software Engineering in Vancouver, Canada. This report is a summary of the workshop and a description of the outcomes.
Synthesis of facially-encumbered porphyrins. An approach to light-harvesting antenna complexes

Abstract 2,6-di- and 2,4,6-tri-benzyloxybenzaldehydes are converted to the respective octa- and dodeca-benzyloxy porphyrins in 9–52% yields via the two-step one-flask room-temperature porphyrin synthesis.
Chiral (salen)CoIII catalyst for the synthesis of cyclic carbonates

A catalyst system comprised of a CoIII(salen) complex and a Lewis base is investigated for the reaction of CO2 and a variety of epoxides to form cyclic carbonates. Application of this catalyst system in the kinetic resolution of propylene oxide is also discussed.
Penguin Mediated B Decays at BABAR

We report on preliminary results of searches for penguin mediated B decays based on 20.7 fb 1 of data collected at the (4S) peak with the BABAR detector at PEP-II. The following branching fractions have been measured: B(B + ! K + )=( 7:7 +1:6
The braid monodromy of plane algebraic curves and hyperplane arrangements

To a plane algebraic curve of degree n, Moishezon associated a braid monodromy homomorphism from a finitely generated free group to Artin's braid group Bn. Using Hansen's polynomial covering space theory, we give a new interpretation of this construction. Next, we provide an explicit description of the braid monodromy of an arrangement of complex affine hyperplanes, by means of an associated "braided wiring diagram". The ensuing presentation of the fundamental group of the complement is shown to be Tietze-I equivalent to the Randell-Arvola presentation. Work of Libgober then implies that the complement of a line arrangement is homotopy equivalent to the 2-complex modeled on either of these presentations. Finally, we prove that the braid monodromy of a line arrangement determines the intersection lattice. Examples of Falk then show that the braid monodromy carries more information than the group of the complement, thereby answering a question of Libgober.
Surges and Sudden Stops of Capital Flows to Emerging Markets

A characteristic of many of the recent emerging market currency crises is a preceding surge in capital inflows and their reversals or ‘sudden stops’ during the crises. The empirical investigation of 38 emerging market economies between 1990 and 2003 reveals that a surge in capital inflows significantly increases the probability of a sudden stop. In addition, a surge accompanied by a high current account deficit or an appreciated real exchange rate is more likely to be associated with a sudden stop. The paper also finds that a surge that is dominated by private loans and portfolio flows rather than direct investment has a higher probability to end with a sudden stop.
National Borders, Conflict and Peace

This paper reviews the economics approach to conflict and national borders. The paper (a) provides a summary of ideas and concepts from the economics literature on the size of nations; (b) illustrates them within a simple analytical framework where populations fight over borders and resources, and may form non-aggression pacts, military alliances, and political unions; and (c) discusses extensions and directions for further research.
Sequential markets and the suboptimality of the Friedman rule

A cash-in-advance model with sequential markets is constructed, where unanticipated monetary injections are nonneutral and can potentially produce large liquidity effects. However, if the monetary authority adheres to an optimal money rule, money should not respond to unanticipated shocks, so that a Friedman rule is suboptimal and the monetary authority does not exploit the liquidity effect. Quantitatively, the model can generate variability in money and nominal interest rates close to what is observed, and can produce data with no obvious evidence of the existence of liquidity effects.
Advantages of an Ellipse when Modeling Leisure Utility

This paper characterizes a specification for the utility of leisure that is based on the general equation for an ellipse. We show that this functional form has multiple benefits. The elliptical utility function provides Inada conditions at both the upper-bound and lower-bound constraints on labor supply, which is not the case for the two most common alternative functions. The presence of these two Inada conditions in the elliptical utility of leisure specification speeds up the computation by a factor between three and six times. We further show that the elliptical utility of leisure function is a close approximation to the constant relative risk aversion and constant Frisch elasticity functions in terms of marginal utilities, microeconomic outcomes in a life cycle model, and macroeconomic outcomes in a simple real business cycle model.
NON-BARYONIC DARK MATTER

These lectures on non-baryonic dark matter matter are divided into two parts. In the first part, I discuss the need for non-baryonic dark matter in light of recent results in cosmology, and I present some of the most popular candidates for non-baryonic dark matter. These include neutrinos, axions, neutralinos, WIMPZILLAs, etc. In the second part, I overview several observational techniques that can be employed to search for WIMPs (weakly interacting massive particles) as non-baryonic dark matter. Among these techniques, I discuss the direct detection of WIMP dark matter, and its indirect detection through high-energy neutrinos, gamma-rays, positrons, etc. References cited in these lectures are intended mostly for further study, and no attempt has been made to provide a comprehensive list of original and recent work on the subject. 1. The need for non-baryonic dark matter We live in a time of great observational advances in cosmology, which have given us a consistent picture of the matter and energy content of our Universe. Here matter and energy (which special relativity tells us are equivalent) are distinguished by their different dependence on the cosmic volume: matter density decreases with the inverse of the volume, while energy density remains (approximately) constant. Nothing is known about the nature of the energy component, which goes under the name of dark energy. Of the matter component, less than 2% is luminous, and no more than 20% i sm ad eo f ordinary matter like protons, neutrons, and electrons. The rest of the matter component, more than 80% of the matter, i so f an unknown form which we call non-baryonic. Finding the nature of non-baryonic matter is referred to as the non-baryonic dark matter problem. A summary of the current measurements of the matter density Ωm an dt he energy density ΩΛ are shown in Figure 1 (adapted from Verde et al.(2002)). Both are in units of the critical density ρcrit =3 H 2 0
Endogenous Liquidity and the Business Cycle

The recent financial crisis was the deepest recession of the post-war era. The recession began with an abrupt collapse in many asset markets. A common view is that this collapse followed a surge in uncertainty about the quality of collateral assets. The consequent shortfall in liquidity may have spread to the real economy because liquidity is essential to finance payroll and investment. This paper presents a theory where liquidity-driven recessions follow from surges in the dispersion of collateral quality. I use this theory to quantify the potential damage to the real economy caused by this class of dispersion shocks. The theory builds on the interaction of two financial frictions: limited enforcement and asymmetric information. Limited contract enforcement prevents transactions if future payments cannot be guaranteed. This constraint can be relaxed if an agent does not promise future payments, but instead makes payments immediately with liquid assets. However, agents hold capital that is illiquid unless it is sold or used as collateral. Asymmetric information about the quality of capital translates into a cost to obtain liquidity. The paper characterizes the decision to obtain liquidity under asymmetric information in order to relax enforcement constraints through a marginal condition.
Does immigration impact institutions

The economics literature generally finds a positive, but small, gain in income to native-born populations from immigrants and potentially large gains in world incomes. But immigrants can also impact a recipient nation’s institutions. A growing empirical literature supports the importance of strong private property rights, a rule of law, and an environment of economic freedom for promoting long-run prosperity. But little is known about how immigration impacts these institutions. This paper empirically examines how immigration impacts a nation’s policies and institutions. We find no evidence of negative and some evidence of positive impacts in institutional quality as a result of immigration.
QoS in ad hoc networks

For mobile ad-hoc networks, nodes must balance a variety of tasks including sensing and communications relays. Mobile nodes might thus change location or trajectory for sensing purposes, subject to constraints on disruption of network QoS. This paper maximizes the non-communication application QoS (node motion to facilitate sensing) with communication QoS constraints (packet delay, etc.). It also gives the formulation for maximizing the throughput for the newly formed links at the new position of the node, taking link capacities into consideration. Each link is shared by multiple streams of traffic from different QoS classes, and each stream traverses many links. Although these formulations are non-linear, they can be posed as geometric programs, which can be solved efficiently. We also propose a heuristic to implement the above algorithm in ad hoc networks.
The ’t Hooft vertex revisited

In 1976 ’t Hooft introduced an elegant approach towards understanding the physical consequences of the topological structures that appear in non-Abelian gauge theories. These effects are concisely summarized in terms of an effective multifermion interaction. These old arguments provide a link between a variety of recent and sometimes controversial ideas including discrete chiral symmetries appearing in some models for unification, ambiguities in the definition of quark masses, and flaws with some simulation algorithms in lattice gauge theory.
Estimation and Identification of Merger Effects: An Application to Hospital Mergers

Abstract Existing empirical estimates of merger effects are compromised by the fact that merging and nonmerging entities differ in unobserved ways that independently affect outcomes of interest. To obtain an unbiased estimate of the effect of consummated mergers, I propose an approach that focuses on the response of rivals to mergers and accounts for the endogeneity of exposure to these mergers. I apply this approach to evaluate the impact of independent hospital mergers in the United States between 1989 and 1996. Using the physical colocation of rivals as an instrument for whether they merge, I find a sizeable, one‐time increase in price following a rival’s merger, with the greatest increase occurring among hospitals nearest the merging hospitals. These results are more consistent with predictions from structural models of the hospital industry than with prior observational estimates of the effects of hospital mergers.
Deviation bounds for wavelet shrinkage

We analyze the wavelet shrinkage algorithm of Donoho and Johnstone (1994) in order to assess the quality of the reconstruction of a signal obtained from noisy samples. We give a deviation estimate for the maximum squared error (and, consequently, for the average squared error), under the assumption that the signal comes from a Holder class, and the noise samples are independent, of zero mean, and bounded. Our main technique is Talagrand's (1995) isoperimetric theorem. Our result shows a better behavior of the wavelet shrinkage.
Discourse topic and gestural form

Coverbal gesture provides a channel for the visual expression of ideas. While some gestural emblems have culturally predefined forms (e.g., "thumbs up"), the relationship between gesture and meaning is, in general, not conventionalized. It is natural to ask whether such gestures can be interpreted in a speaker-independent way, or whether gestural form is determined by the speaker's idiosyncratic view of the discourse topic. We address this question using an audiovisual dataset across multiple speakers and topics. Our analysis employs a hierarchical Bayesian author-topic model, in which gestural patterns are stochastically generated by a mixture of speaker-specific and topic-specific priors. These gestural patterns are characterized using automatically-extracted visual features, based on spatio-temporal interest points. This framework detects significant cross-speaker patterns in gesture that are governed by the discourse topic, suggesting that even unstructured gesticulation can be interpreted across speakers. In addition, the success of this approach shows that the semantic characteristics of gesture can be detected via a low-level, interest point representation.
Exploring new non-sugar sulfated molecules as activators of antithrombin.

Abstract New non-sugar, small, sulfated molecules, based on our de novo rationally designed activator (−)-epicatechin sulfate (ECS), were investigated to bind and activate antithrombin, an inhibitor of plasma coagulation enzyme factor Xa. For the activators studied, the equilibrium dissociation constant ( K D ) of the interaction with plasma antithrombin varies nearly 53-fold, with the highest affinity of 1.8 μM observed for morin sulfate, while the acceleration in factor Xa inhibition varies 2.6-fold. The results demonstrate that antithrombin binding and activation is a common property of these small sulfated molecules and suggests plausible directions for designing more potent activators.
Computer Science as a Lens on the Sciences

Summary form only given. This article trace the growing influence of fundamental ideas from computer science on the nature of research in a number of scientific fields. There is a growing awareness that information processing lies at the heart of the processes studied in fields as diverse as quantum mechanics, statistical physics, nanotechnology, neuroscience, linguistics, economics and sociology. Increasingly, mathematical models in these fields are expressed in algorithmic languages and describe algorithmic processes. The author describe connections between quantum computing and the foundations of quantum mechanics, and between statistical mechanics and phase transitions in computation. The author indicates how the growth of the Web has created new phenomena to be investigated by sociologists and economists, spurring new developments in computational game theory and the study of social networks. The author then focus on computational molecular biology, where the view of living cells as complex information processing systems has become the dominant paradigm.
Enantioselective α-Alkylation of Aldehydes by Photoredox Organocatalysis: Rapid Access to Pharmacophore Fragments from β-Cyanoaldehydes

The combination of photoredox catalysis and enamine catalysis has enabled the development of an enantioselective α-cyanoalkylation of aldehydes. This synergistic catalysis protocol allows for the coupling of two highly versatile yet orthogonal functionalities, allowing rapid diversification of the oxonitrile products to a wide array of medicinally relevant derivatives and heterocycles. This methodology has also been applied to the total synthesis of the lignan natural product (−)-bursehernin.
Complex Polyanionic Nets in RbAu4.01(2)Ga8.64(5) and CsAu5Ga9: The Role of Cations in the Formation of New Polar Intermetallics

Two new alkali metal-poor phases with gold and gallium have been synthesized and structurally characterized using single-crystal X-ray diffraction. RbAu4.01(2)Ga8.64(5) (I) crystallizes in a new tetragonal structure type (tI163.8; I4/m, a = 8.806(1), c = 40.561(8) A, Z = 12). The structure of I contains two types of (defect) icosahedra and three types of Rb-centered distorted snub cubes composed of gold and gallium atoms, so that it is a novel tetragonal superstructure of the defect NaZn13-type structure. The defect icosahedra, which are fully centered by Ga atoms, show distortions that minimize the number of Au–Au contacts as well as having a distribution of vacancies that create 12-atom, 11-atom, and 10-atom polyhedra. CsAu5Ga9 (II) crystallizes with a hexagonal unit cell (hP30; P63/mmc, a = 7.635(1), c = 12.279(3) A, Z = 2) in the BaNi9P5 structure type and is the first intermetallic compound of this type. This structure involves a 3-d network of gold atoms, gallium atoms, and Ga–Ga dimers that form Cs@Au12Ga18 polyhedra, which share hexagonal faces along the c-axis and pentagonal bipyramids in the ab-plane. Its structure shares a resemblance with the hexagonal ZrBeSi structure type. Both compounds exhibit unusually large coordination polyhedra of gold and gallium atoms surrounding each alkali metal with up to 30 near neighbors and a reasonably dense packing. Tight-binding electronic structure calculations on CsAu5Ga9 indicate that although the average Ga–Ga orbital interactions are optimized at the Fermi level, the specific interactions are not.
A Comparison of Password Techniques for Multilevel Authentication Mechanisms

Various mechanisms for authenticating users of computer-based information systems have been proposed. These include traditional, user-selected passwords, system-generated passwords, passphrases, cognitive passwords and associative passwords. While the mechanisms employed in primary passwords are determined by the operating systems'manufacturers, system designers can select any password mechanism for secondary passwords, to further protect sensitive applications and data files. This paper reports on the results of an empirically based study of passwords characteristics. It provides a comparative evaluation on the memorability and users'subjective preferences of the various passwords mechanims, and suggests that cognitive passwords and associative passwords seem the most appropriate for secondary passwords
Spin order in paired quantum Hall states.

We consider quantum Hall states at even-denominator filling fractions, especially $\ensuremath{\nu}=5/2$, in the limit of small Zeeman energy. Assuming that a paired quantum Hall state forms, we study spin ordering and its interplay with pairing. We give numerical evidence that at $\ensuremath{\nu}=5/2$ an incompressible ground state will exhibit spontaneous ferromagnetism. The Ginzburg-Landau (GL) theory for the spin degrees of freedom of paired Hall states is a perturbed $C{P}^{2}$ model. We compute the coefficients in the GL theory by a BCS Stoner mean-field theory for coexisting order parameters, and show that even if repulsion is smaller than that required for a Stoner instability, ferromagnetic fluctuations can induce a partially or fully polarized superconducting state.
Development of a VII-enabled prototype intersection collision warning system

This paper presents the design of a prototype intersection collision warning system based on Vehicle Infrastructure Integration (VII). This system involves Roadside Equipment (RSE) at an intersection and several units of On-Board Equipment (OBE), each in a moving vehicle. When an equipped vehicle approaches the intersection, its OBE queries the remaining time before the light turns red from the RSE which is synchronised with the intersection signal. Combining its own speed and position, the OBE determines the likelihood of running the red light. In case of such a hazard, the OBE warns its driver and notifies other OBEs wirelessly.
Cross-Selling in a Call Center with a Heterogeneous Customer Population

Cross-selling is becoming an increasingly prevalent practice in call centers, due, in part, to its unique capability to allow firms to dynamically segment their callers and customize their product offerings accordingly. This paper considers a call center with cross-selling capability that serves a pool of customers that are differentiated in terms of their revenue potential and delay sensitivity. It studies the operational decisions of staffing, call routing, and cross-selling under various forms of customer segmentation. It derives near-optimal controls in each of the settings analyzed, and characterizes the impact of a more refined customer segmentation on the structure of these policies and the center's profitability.