cssi/SciSciGPT-SciSciNet huggingface dataset:
Three-dimensional instabilities in compressible flow over open cavities

Direct numerical simulations are performed to investigate the three-dimensional stability of compressible flow over open cavities. A linear stability analysis is conducted to search for three-dimensional global instabilities of the two-dimensional mean flow for cavities that are homogeneous in the spanwise direction. The presence of such instabilities is reported for a range of flow conditions and cavity aspect ratios. For cavities of aspect ratio (length to depth) of 2 and 4, the three-dimensional mode has a spanwise wavelength of approximately one cavity depth and oscillates with a frequency about one order of magnitude lower than two-dimensional Rossiter (flow/acoustics) instabilities. A steady mode of smaller spanwise wavelength is also identified for square cavities. The linear results indicate that the instability is hydrodynamic (rather than acoustic) in nature and arises from a generic centrifugal instability mechanism associated with the mean recirculating vortical flow in the downstream part of the cavity. These three-dimensional instabilities are related to centrifugal instabilities previously reported in flows over backward-facing steps, lid-driven cavity flows and Couette flows. Results from three-dimensional simulations of the nonlinear compressible Navier–Stokes equations are also reported. The formation of oscillating (and, in some cases, steady) spanwise structures is observed inside the cavity. The spanwise wavelength and oscillation frequency of these structures agree with the linear analysis predictions. When present, the shear-layer (Rossiter) oscillations experience a low-frequency modulation that arises from nonlinear interactions with the three-dimensional mode. The results are consistent with observations of low-frequency modulations and spanwise structures in previous experimental and numerical studies on open cavity flows.
A vision system for robotic inspection and manipulation

A model-based approach has been proposed to make object recognition computationally tractable. In this approach, models associated with objects expected to appear in the scene are recorded in the system's knowledge base. The system extracts various features from the input images using robust, low-level, general-purpose operators. Finally, matching is performed between the image-derived features and the scene domain models to recognize objects. Factors affecting the successful design and implementation of model-based vision systems include the ability to derive suitable object models, the nature of image features extracted by the operators, a computationally effective matching approach, knowledge representation schemes, and effective control mechanisms for guiding the systems's overall operation. The vision system they describe uses gray-scale images, which can successfully handle complex scenes with multiple object types. >
Local parallel computation of stochastic completion fields

We describe a local parallel method for computing the stochastic completion field introduced in an earlier paper Williams and Jacobs (1995). The stochastic completion field represents the likelihood that a completion joining two contour fragments passes through any given position and orientation in the image plane. It is based upon the assumption that the prior probability distribution of completion shape can be modeled as a random walk in a lattice of discrete positions and orientations. The local parallel method can be interpreted as a stable finite difference scheme for solving the underlying Fokker-Planck equation identified by Mumford (1994). The resulting algorithm is significantly faster than the previously employed method which relied on convolution with large-kernel filters computed by Monte Carlo simulation. The complexity of the new method is Of(n/sup 3/m) while that of the previous algorithm was 0(n/sup 4/m/sup 2/) (for an n x n image with m discrete orientations). Perhaps most significantly, the use of a local method allows us to model the probability distribution of completion shape using stochastic processes which are neither homogenous nor isotropic.
p-WAVE Pairing in Fermi Systems with Unequal Population Near Feshbach Resonance

We explore p-wave pairing in a single-channel two-component Fermi system with unequal population near Feshbach resonance. Our analytical and numerical study reveal a rich superfluid (SF) ground state structure as a function of imbalance. In addition to the state Δ±1 ∝ Y1±1, a multitude of “mixed” SF states formed of linear combinations of Y1m's give global energy minimum under a phase stability condition; these states exhibit variation in energy with the relative phase between the constituent gap amplitudes. States with local energy minimum are also obtained. We provide a geometric representation of the states. A T = 0 polarization vs. p-wave coupling phase diagram is constructed across the BEC-BCS regimes. With increased polarization, the global minimum SF state may undergo a quantum phase transition to the local minimum SF state.
Stability-optimized, force-cooled, multifilamentary superconductors

A numerical program has been written to calculate the temperature-time history of a uniformly pulse-heated composite superconductor cooled by supercritical helium in forced convection. The program determines the maximum sudden temperature rise from which the conductor can still recover the superconducting state. The program includes the effects of (1) current sharing, (2) the temperature variation of the specific heat of both the matrix and the superconductor, and (3) the temperature variation of the heat transfer coefficient. Using this program, one may optimize force-cooled conductors with respect to stability by simultaneously varying the copper-to-superconductor (Cu/SC) ratio and the metal-to-helium ratio. Use of stability-optimized conductors allows a given stability level to be maintained for a particular field and bath temperature and the pressure drop and pumping losses to be reduced.
REGIONAL CHANGES IN THE DISTRIBUTION OF NET VALUE ADDED IN U.S. AGRICULTURE, 1960-2002

This paper examines the effects of structural changes on the distribution of net value added and the difference between net value added and agricultural income over time. We present and discuss the changes in the distribution of net value added (land, labor, capital, and farm operator income) over time. Net value added by U.S. agriculture grew significantly from $18 billion to 1960 to $95 billion in 1996. We examine regional differences in net value added using the Theil entropy measure. The inequality (dispersion) of net value added increased over time. The increased inequality represented both increases in regional dispersion in net value added and increases in the average inequality in net value added in each region. Thus, the net value added is becoming less alike across the U.S. We also examined the inequality in the components of net value added. The greatest dispersion occurred in returns to land followed by returns to capital. Therefore, changes in the dispersion of net value added by agriculture are explained by differences in the payments to non-operator landlords and to capital.
Solutions of the compressible Navier-Stokes equations using the integral method

The integral representation method was used to obtain numerical solutions of the compressible, unsteady, two-dimensional Navier-Stokes equations for subsonic flows. The equations were written with the vorticity, the dilatation, the density, and the enthalpy as the dependent variables. The method was tested by solving the following problems: the flow over a flat plate, around a circular cylinder, and around a Joukowski airfoil. The last two problems involved massive flow separation. The approach offers the capability of confining the domain of computations to the region where two quantities, the vorticity and the difference in dilatation between the real flow and the potential flow around the body, are non-negligible.
Tailoring Chimeric Ligands for Studying and Biasing ErbB Receptor Family Interactions

Described is the development and application of a versatile semisynthetic strategy, based on a combination of sortase-mediated coupling and tetrazine ligation chemistry, which can be exploited for the efficient incorporation of tunable functionality into chimeric recombinant proteins. To demonstrate the scope of the method, the assembly of a set of bivalent ligands, which integrate members of the epidermal growth factor (EGF) ligand family, is described. By using a series of bivalent EGFs with variable intraligand spacing, the differences in structure were correlated with the ability to bias signaling in the ErbB receptor family in a cell motility assay. Biasing away from EGFR-HER2 dimerization with a bivalent EGF was observed to reduce cell motility in an intraligand distance-dependent fashion, thus demonstrating the utility of the approach for acutely perturbing receptor-mediated cell signaling pathways.
Wronskians, generalized Wronskians and solutions to the Korteweg–de Vries equation

A bridge going from Wronskian solutions to generalized Wronskian solutions of the Korteweg–de Vries (KdV) equation is built. It is then shown that generalized Wronskian solutions can be viewed as Wronskian solutions. The idea is used to generate positons, negatons and their interaction solutions to the KdV equation. Moreover, general positons and negatons are constructed through the Wronskian formulation. A few new exact solutions to the KdV equation are explicitly presented as examples of Wronskian solutions.
Public interest litigation in India : overreaching or underachieving ?

Public interest litigation has historically been an innovative judicial procedure for enhancing the social and economic rights of disadvantaged and marginalized groups in India. In recent years, however, a number of criticisms of public interest litigation have emerged, including concerns related to separation of powers, judicial capacity, and inequality. These criticisms have tended to abstraction, and the sheer number of cases has complicated empirical assessments. This paper finds that public interest litigation cases constitute less than 1 percent of the overall case load. The paper argues that complaints related to concerns having to do with separation of powers are better understood as criticisms of the impact of judicial interventions on sector governance. On the issue of inequality, the analysis finds that win rates for fundamental rights claims are significantly higher when the claimant is from an advantaged social group than when he or she is from a marginalized group, which constitutes a social reversal, both from the original objective of public interest litigation and from the relative win rates in the 1980s.
Definitional and Contextual Issues in Organizational and Group Memories

Describes how organizations looking to augment their memories through information technologies can employ an organizational memory system. Organizational and group memories can include a wide variety of materials, including documents, rationales for decisions, formal descriptions of procedures, and so on. Discusses findings from case studies of six organizations using or attempting to use the Answer Garden, a type of organizational memory system. Examines two major issues in the implementation of such systems: the gap between the idealized definition of organizational memory and the constrained realities of organizational life; and the effects of reducing contextual information in computer‐based memory. Suggests some avenues for managing these issues as well as for further technical and organizational research.
Evaluating order of circuits for deadlock avoidance in a flexible manufacturing system

In modern highly automated flexible manufacturing systems, various parts are processed concurrently. Due to the concurrency and shared equipment usage, deadlock is a common problem that causes loss of productivity. When such a system is modelled by a digraph, existence of circuits in such a graph is a necessary condition for deadlock and knots and the order of circuits are closely related to impending deadlocks – a type of deadlock that is more difficult to detect. A deadlock avoidance algorithm that dynamically evaluates the order of circuits is presented. The algorithm is highly permissive since the order evaluation captures more part flow dynamics, especially when there exist multiple knots in the digraph model. It also runs in polynomial time once the set of circuits of the digraph is given. Simulation results are provided to illustrate the application of the algorithm.
The influence of online word-of-mouth on long tail formation

The long tail phenomenon has been attributed to both supply side and demand side economies. While the cause on the supply side is well-known, research on the demand side has largely focused on the awareness effect of online information that helps consumers discover new and often niche products. This study expands the demand side factors by showing that online information also influences the long tail phenomenon through the informative effect, which affects consumers' evaluation of product quality. We examine the informative effect in the context of online WOM. Two sets of theories suggest opposite directions for the implication of the informative effect. Information search and information cascade literatures indicate that WOM provides additional information to consumers, reduces the occurrence of information cascade, and encourages the formation of long tail. Studies on behavior heuristics, however, suggest that consumers tend to ignore online information inconsistent with their prior beliefs, which leads to a rich-gets-richer effect for popular products and curtail the formation of the long tail. We empirically examine the conflict by analyzing different impacts of online WOM across product popularity and WOM ratings. Using a panel data collected from Amazon.com, we show that positive reviews improve the sales of popular products more than the sales of niche products, while negative reviews hurt niche products more than popular products. The results are consistent with the prediction of the behavior heuristic and suggest that online WOM restrains the formation of long tail.
Catching a viral video

The sharing and re-sharing of videos on social sites, blogs e-mail, and other means has given rise to the phenomenon of viral videos--videos that become popular through internet sharing. In this paper we seek to better understand viral videos on YouTube by analyzing sharing and its relationship to video popularity using millions of YouTube videos. The socialness of a video is quantified by classifying the referrer sources for video views as social (e.g. an emailed link, Facebook referral) or non-social (e.g. a link from related videos). We find that viewership patterns of highly social videos are very different from less social videos. For example, the highly social videos rise to, and fall from, their peak popularity more quickly than less social videos. We also find that not all highly social videos become popular, and not all popular videos are highly social. By using our insights on viral videos we are able develop a method for ranking blogs and websites on their ability to spread viral videos.
Comparison of accelerator codes for a RHIC lattice

The results of comparisons of the performances of several tracking and/or analysis codes are presented. The basic purpose of this program was to assess the reliability and accuracy of these codes, i.e. to determine the so-called error bars for the predicted values of tunes and other lattice functions as a minimum and, if possible, to discover potential difficulties (inadequate algorithms, residual bugs, etc.) with the underlying physical models in these codes. Not only was it possible to determine the error bars, which, for instance, for the tunes at dp/p=+1% are Delta nu /sub x/=0.0027, Delta nu /sub y/=0.0010, but also the program has brought about improvements of several codes. >
Oracles for structural properties: the isomorphism problem and public-key cryptography

Abstract There exists an oracle, relative to which, P ≠ NP, and each of the following properties hold: 1. (i)All Σ 2 P -complete sets are p-isomorphic; 2. (ii)P-inseparable pairs of sets in NP do not exist; 3. (iii)Intractable public-key cryptosystems do not exist; 4. (iv)NP-complete sets are closed under union of disjoint sets. Remarkably, these properties all follow from one oracle construction. Namely, we prove that there is an oracle A such that every two disjoint sets in NP A are P-separable, and Σ 2 P = U DTIME(2 P )| p is a polynomial. Additional related relativization results are presented also.
α,β-Unsaturated imines from titanium hydroamination and functionalization by rhodium C–H activation

Titanium pyrrolyl complexes are effective catalysts for the synthesis of α,β-unsaturated imines, which can be further functionalized using Rh-catalyzed alkene or alkyne insertion into the β-C–H bond.
Enhancing the Teaching of Statistics: Portfolio Theory, an Application of Statistics in Finance.

In this paper we present an application of statistics using real stock market data. Most, if not all, students have some familiarity with the stock market (or at least they have heard about it) and therefore can understand the problem easily. It is the real data analysis that students find interesting. Here we explore the building of efficient portfolios through optimization using examples of two and three stocks, and how covariance and correlation can help the investor to diversify his or her risk. We discuss why diversification works, but also the problems that arise in portfolio management. Stock market data can be incorporated at any level of statistics, from lower division, to upper division, to graduate courses of Mathematics and Statistics. From our experience, students find this topic very interesting and often they want to enroll in other courses related to this area.
Faster Bootstrapping with Polynomial Error

Bootstrapping is a technique, originally due to Gentry (STOC 2009), for “refreshing” ciphertexts of a somewhat homomorphic encryption scheme so that they can support further homomorphic operations. To date, bootstrapping remains the only known way of obtaining fully homomorphic encryption for arbitrary unbounded computations.
Unintended impacts of increased truck loads on pavement supply-chain emissions

In recent years, the reduction of freight truck trips has been a common policy goal. To this end, policies aimed at influencing load consolidation have been suggested and implemented, resulting in higher gross vehicle weights. The purpose of such policies has generally been to mitigate congestion and environmental impacts. However, trucks cause most of the damage incurred by pavements. The supply chain associated with pavement maintenance and construction releases significant air emissions, raising the question of whether increased vehicle weights may cause unintended environmental consequences. This paper presents scenarios with estimated emissions resulting from load consolidation and changes in load factors. These scenarios reveal several points having to do with the tradeoff between tailpipe versus pavement supply-chain emissions. In some cases, unintended emissions from the pavement supply chain are found to be significant.
Laura Chisolm: An Advocate and Ally

I worked with Laura Chisolm primarily in my capacity as Associate Director of the Center for Social Justice, of which she was the founding Director. Yet--as is probably true of many of my colleagues at the law school--I came to know and admire her most as a fellow faculty member, friend, and mentor. I will never forget the many kindnesses from Laura--not least of all the baby gift she sent me after my older daughter was born. It was a beautiful, fuzzy, hand-knit sweater that kept both my older daughter and my younger daughter warm for, literally, years. Where on earth such an accomplished and busy person found time to knit a sweater, I have no idea, but this sort of thing was typical, given Laura's thoughtfulness, her overwhelming kindness, and her capacious talents.
Improved local algorithms for spanner construction

Let S be a set of n points in the plane, let E be the complete Euclidean graph whose point set is S, and let G be the Delaunay triangulation of S. We present a very simple local algorithm that, given G, constructs a subgraph of G of degree at most 11 that is a geometric spanner of G with stretch factor 2.86, and hence a geometric spanner of E with stretch factor < 7. This algorithm gives an O(nlgn) time centralized algorithm for constructing a subgraph of G that is a geometric spanner of E of degree at most 11 and stretch factor <7.
Vascular amyloidosis impairs the gliovascular unit in a mouse model of Alzheimer’s disease

Reduced cerebral blood flow impairs cognitive function and ultimately causes irreparable damage to brain tissue. The gliovascular unit, composed of neural and vascular cells, assures sufficient blood supply to active brain regions. Astrocytes, vascular smooth muscle cells, and pericytes are important players within the gliovascular unit modulating vessel diameters. While the importance of the gliovascular unit and the signals involved in regulating local blood flow to match neuronal activity is now well recognized, surprisingly little is known about this interface in disease. Alzheimer's disease is associated with reduced cerebral blood flow. Here, we studied how the gliovascular unit is affected in a mouse model of Alzheimer's disease, using a combination of ex vivo and in vivo imaging approaches. We specifically labelled vascular amyloid in living mice using the dye methoxy-XO4. We elicited vessel responses ex vivo using either pharmacological stimuli or cell-specific calcium uncaging in vascular smooth muscle cells or astrocytes. Multi-photon in vivo imaging through a cranial window allowed us to complement our ex vivo data in the presence of blood flow after label-free optical activation of vascular smooth muscle cells in the intact brain. We found that vascular amyloid deposits separated astrocyte end-feet from the endothelial vessel wall. High-resolution 3D images demonstrated that vascular amyloid developed in ring-like structures around the vessel circumference, essentially forming a rigid cast. Where vascular amyloid was present, stimulation of astrocytes or vascular smooth muscle cells via ex vivo Ca(2+) uncaging or in vivo optical activation produced only poor vascular responses. Strikingly, vessel segments that were unaffected by vascular amyloid responded to the same extent as vessels from age-matched control animals. We conclude that while astrocytes can still release vasoactive substances, vascular amyloid deposits render blood vessels rigid and reduce the dynamic range of affected vessel segments. These results demonstrate a mechanism that could account in part for the reduction in cerebral blood flow in patients with Alzheimer's disease.media-1vid110.1093/brain/awv327_video_abstractawv327_video_abstract.
Heterogeneous Responses to Market Information and The Impact on Price Volatility and Trading Volume: The Case of Class III Milk Futures

Under the theoretical intraday microstructure framework, we analyze the impact of traders’ heterogeneous responses to market information on daily futures price and trading activity by utilizing the unique features of Class III milk futures contract. The cash settlement and classified pricing scheme distinguish milk futures from other commodities. We construct two variables, days to maturity and price deviates, to capture the distinctive features. While days to maturity indicate the length of time before cash settlement in the maturity month, price deviates reflect traders’ heterogeneous responses to weekly published information on milk prices. A structural price volatility-trading volume model is specified and is estimated using the Bayesian Markov chain Monte Carlo method. The results confirm that (i) the closer to cash settlement, the lower milk futures price volatility, which is opposite to the typical “Samuelson effect” for other commodity futures, and (ii) both price variability and trading volume are increasing functions of traders’ heterogeneous responses to market information and therefore are positively associated. The results can be seen as evidence that the USDA weekly published information has significant impact on price and trading activities in the milk futures market.
Epitaxial stabilization and phase instability of VO2 polymorphs

The VO2 polymorphs, i.e., VO2(A), VO2(B), VO2(M1) and VO2(R), have a wide spectrum of functionalities useful for many potential applications in information and energy technologies. However, synthesis of phase pure materials, especially in thin film forms, has been a challenging task due to the fact that the VO2 polymorphs are closely related to each other in a thermodynamic framework. Here, we report epitaxial stabilization of the VO2 polymorphs to synthesize high quality single crystalline thin films and study the phase stability of these metastable materials. We selectively deposit all the phases on various perovskite substrates with different crystallographic orientations. By investigating the phase instability, phonon modes and transport behaviours, not only do we find distinctively contrasting physical properties of the VO2 polymorphs, but that the polymorphs can be on the verge of phase transitions when heated as low as ~400 °C. Our successful epitaxy of both VO2(A) and VO2(B) phases, which are rarely studied due to the lack of phase pure materials, will open the door to the fundamental studies of VO2 polymorphs for potential applications in advanced electronic and energy devices.
System identification and simulation: a pattern recognition approach

Recent years have seen continuing and increasingly-intensive attempts to extend the art of simulation to areas which heretofore were considered too complex and too difficult to lend themselves to conventional modelling and simulation techniques. These include such environment-oriented fields as air-pollution, water conservation, thermal pollution, etc., as well as systems belonging to the biological, the medical, the economic, and sociological areas. For example, in 1970 the Office of Water Resources Research catalogued over 600 on-going research projects concerned with the modelling of water resource systems. The extension of simulation techniques developed in application areas such as control system design, electro-mechanical systems, etc., to these new areas has often been disappointing, if not completely unsuccessful. This is due to the difficulty in constructing a sufficiently-valid mathematical model---a model which can be used for prediction with a reasonable amount of confidence. It is well-known, of course, that even under the best conditions, inverse problems such as system identification problems, do not have unique solutions. That is, inevitably an infinite number of possible models will satisfy a specified set of excitation/response relationships. Where the identification process is further handicapped by uncertainties as to system structure and inadequate experimental data, the pertinent question is often not: "How good is the model?" but rather: "Is there any point to modelling at all?"
Using course-subject Co-occurrence CSCO to reveal the structure of an academic discipline: A framework to evaluate different inputs of a domain map

This article proposes, exemplifies, and validates the use of course-subject co-occurrence CSCO data to generate topic maps of an academic discipline. A CSCO event is when 2 course-subjects are taught in the same academic year by the same teacher. A total of 61,856 CSCO events were extracted from the 2010-11 directory of the American Association of Law Schools and used to visualize the structure of law school education in the United States. Different normalization, ordination layout, and clustering algorithms were compared and the best performing algorithm of each type was used to generate the final map. Validation studies demonstrate that CSCO produces topic maps that are consistent with expert opinion and 4 other indicators of the topical similarity of law school course-subjects. This research is the first to use CSCO to produce a visualization of a domain. It is also the first to use an expanded, multi-part gold standard to evaluate the validity of domain maps and the intermediate steps in their creation. It is suggested that the framework used herein may be adopted for other studies that compare different inputs of a domain map in order to empirically derive the best maps as measured against extrinsic sources of topical similarity gold standards.
PERIODIC DENSITY STRUCTURES AND THE ORIGIN OF THE SLOW SOLAR WIND

The source of the slow solar wind has challenged scientists for years. Periodic density structures (PDSs), observed regularly in the solar wind at 1 AU (Astronomical Unit), can be used to address this challenge. These structures have length scales of hundreds to several thousands of megameters and frequencies of tens to hundreds of minutes. Two lines of evidence indicate that PDSs are formed in the solar corona as part of the slow solar wind release and/or acceleration processes. The first is corresponding changes in compositional data in situ, and the second is PDSs observed in the inner Heliospheric Imaging data on board the Solar Terrestrial Relations Observatory (STEREO)/Sun Earth Connection Coronal and Heliospheric Investigation (SECCHI) suite. The periodic nature of these density structures is both a useful identifier as well as an important physical constraint on their origin. In this paper, we present the results of tracking periodic structures identified in the inner Heliospheric Imager in SECCHI back in time through the corresponding outer coronagraph (COR2) images. We demonstrate that the PDSs are formed around or below 2.5 solar radii-the inner edge of the COR2 field of view. We compute the occurrence rates of PDSs in 10 days of COR2 images both as a function of their periodicity and location in the solar corona, and we find that this set of PDSs occurs preferentially with a periodicity of approximately 90 minutes and occurs near streamers. Lastly, we show that their acceleration and expansion through COR2 is self-similar, thus their frequency is constant at distances beyond 2.5 solar radii.
Animal Behavior and Wildlife Conservation

Book Review: Animal Behavior and Wildlife Conservation, Marco Festa-Bianchet, Marco Apollonio. Island Press, Washington, DC (2003).
Finite dimensional Hopf actions on deformation quantizations

We study when a finite dimensional Hopf action on a quantum formal deformation A of a commutative domain A_0 (i.e., a deformation quantization) must factor through a group algebra. In particular, we show that this occurs when the Poisson center of the fraction field of A_0 is trivial.
Crowdsourcing Accessibility: Human-Powered Access Technologies

People with disabilities have always engaged the people around them inorder to circumvent inaccessible situations, allowing them to live moreindependently and get things done in their everyday lives. Increasingconnectivity is allowing this approach to be extended to wherever andwhenever it is needed. Technology can leverage this human work forceto accomplish tasks beyond the capabilities of computers, increasinghow accessible the world is for people with disabilities. This articleoutlines the growth of online human support, outlines a number ofprojects in this space, and presents a set of challenges and opportunitiesfor this work going forward.
Fluctuations in uncertainty, efficient borrowing constraints and firm dynamics

In this paper, I quantify the importance of microeconomic uncertainty shocks for the firm dynamics over the business cycle in an economy with frictional financial markets. To begin, I document facts on asymmetric response across age and size groups of firms in the U.S. to the changes in aggregate economic conditions. I argue that age rather than size is a relevant margin for the magnitude of employment volatility over the cycle; in particular total employment of young firms varies 2.6 times more relative to the old firms. Then I propose a theory that, contrary to the existing studies, generates endogenously a link between firm's age and size and its ability to obtain financing, and induces an asymmetric response to shocks. A key element of my theory is a financial friction originating from the presence of the firm's private information and long-term, efficient lending contract between a risk averse entrepreneur and financial intermediary, which manifests itself as a borrowing constraint. I argue that, for any given expected return on project, young firms are more constrained in borrowing and they grow out of the constraint as they age up to the optimal, unconstrained size. Next I establish that, for any given age, firm's financing increases in line with the average return on a project. In times of high idiosyncratic uncertainty the financial contract calls for tightening of the borrowing constraint transmitting the initial impulse into a decline in demand for production inputs and further, including general equilibrium effects, into an economic downturn. This mechanism affects disproportionally young firms. Not only are they more constrained in borrowing but also they start smaller due to a reduced level of initial financing. A quantitative version of the model accounts for the fall of the aggregate output, employment and investment, decline of credit to GDP ratio and asymmetric employment dynamics of different groups of firms observed in the US data in recessions.
What makes US government bonds safe assets

US government bonds are considered to be the world's safe store of value, especially during periods of economic turmoil such as the events of 2008. But what makes US government bonds "safe assets"? We highlight coordination among investors, and build a model in which two countries with heterogeneous sizes issue bonds that may be chosen as safe asset. Our model illustrates the benefit of a large absolute debt size as safe asset investors have "nowhere else to go" in equilibrium, and the large country's bonds are chosen as the safe asset. Moreover, the effect becomes stronger in crisis periods.
High -Pressure Synthesis and Characterization of Incompressible Titanium Pernitride

TiN2 is prepared in a laser-heated diamond anvil cell using pre-compressed TiN flakes surrounded by a dense N2 pressure transmitting medium (Re gaskets, 73 GPa, 2400 K).
Iron Borophosphate as a Potential Cathode for Lithium- and Sodium-Ion Batteries

Lithium iron borophosphate, Li0.8Fe(H2O)2[BP2O8]·H2O, with a chiral 65 helical channel structure has been shown to be electrochemically active as the cathode for both Li- and Na-ion batteries. We report here, for the first time, synthesis of the illusive Li-containing iron borophosphate of a well-known structure type by employing a hydrothermal synthesis route. The compound has been characterized by single-crystal X-ray diffraction, magnetic measurement, and Mossbauer spectroscopy, which unequivocally prove the mixed valency of Fe2+/3+. The compound exhibits a sloppy voltage profile reminiscent of single-phase solid-solution-type behavior on electrochemical lithium and sodium insertion in the voltage range of 2.1–4.0 V and 1.6–4.0 V, respectively. The pure single-phase oxidized end-member Fe(H2O)2[BP2O8]·H2O was synthesized by chemical delithiation of the as-synthesized compound, and the structure was solved by ab initio methods, followed by Rietveld refinement of the synchrotron powder X-ray diffraction ...
Synthesis of unsymmetrical 3,4-diaryl-3-pyrrolin-2-ones utilizing pyrrole Weinreb amides.

A regiocontrolled synthesis of unsymmetrical 3,4-diaryl-3-pyrrolin-2-ones has been achieved in three steps from 1,2-diaryl-1-nitroethenes with pyrrole-2-carboxamides (pyrrole Weinreb amides) serving as the key linchpin intermediates. Two different methods for the preparation of the requisite nitroalkenes were investigated: (1) modified Henry reaction between arylnitromethanes and arylimines; and (2) Suzuki–Miyaura cross-coupling reaction of 2-aryl-1-bromo-1-nitroethenes with arylboronic acids. Some difficulty was encountered in the preparation of arylnitromethanes, thus leading to the exploration of a cross-coupling strategy that proved more useful. A Barton–Zard pyrrole cyclocondensation reaction between 1,2-diaryl-1-nitroethenes and N-methoxy-N-methyl-2-isocyanoacetamide gave the corresponding pyrrole Weinreb amides, which were then converted into the desired 3-pyrrolin-2-ones in two steps. Overall, this method allowed for the construction of 3,4-diaryl-3-pyrrolin-2-ones with complete regiocontrol of th...
Correlates of Decentralization: Closed and Open Systems Perspectives

This study examines the impact of size, technology, dependence, market condition, and organizational concern toward task environmental factors on decentralization. The results show that the degree ...
Improved Synthesis of Mono- and Disubstituted 2-Halonicotinonitriles from Alkylidene Malononitriles

Pyridines with 2,3,4 and/or 5 substitution remain challenging to prepare. Existing strategies to form multisubstituted 2-halonicotinonitriles via enamines suffer from dimerization of the starting a...
Synthesis of substituted 2-aminoimidazoles via Pd-catalyzed alkyne carboamination reactions. Application to the synthesis of preclathridine natural products.

A new method for the synthesis of 2-aminoimidazole products is described. The heterocyclic products are generated in good yields via Pd-catalyzed carboamination reactions of N-propargyl guanidines and aryl triflates. This methodology generates both a C–N and C–C bond during the annulation step and facilitates the rapid construction of 2-aminoimidazole products with different aryl groups. The utility of this methodology was demonstrated in the total synthesis of preclathridine A, preclathridine B, and dorimidazole B from a single intermediate.
Barack Obama Blindness (BOB): Absence of Visual Awareness to a Single Object

In two experiments we evaluated whether a perceiver’s prior expectations could alone obliterate his or her awareness of a salient visual stimulus. To establish expectancy, observers first made a demanding visual discrimination on each of three baseline trials. Then, on a fourth, critical trial, a single, salient and highly visible object appeared in full view at the center of the visual field and in the absence of any competing visual input. Surprisingly, fully half of the participants were unaware of the solitary object in front of their eyes. Dramatically, observers were blind even when the only stimulus on display was the face of U.S. President Barack Obama. We term this novel, counterintuitive phenomenon, Barack Obama Blindness (BOB). Employing a method that rules out putative memory effects by probing awareness immediately after presentation of the critical stimulus, we demonstrate that the BOB effect is a true failure of conscious vision.
Direct single-shot observation of millimeter-wave superradiance in Rydberg-Rydberg transitions

We have directly detected millimeter-wave (mm-wave) free-space superradiant emission from Rydberg states (principal quantum number $n\ensuremath{\sim}30$) of barium atoms in single-shot experiments. We trigger the cooperative effects with a weak initial pulse and detect the time-dependent amplitude and phase of the emitted radiation with single-shot sensitivity and 20 ps time resolution. This allows measurement and shot-by-shot analysis of the statistical distribution of decay rates, time delays, and time-dependent frequency shifts. Cooperative line shifts and decay rates are observed that exceed the 250 kHz Doppler width by a factor of 20 and the 50 Hz spontaneous emission rate by a factor of ${10}^{5}$.
GDP-to-GTP exchange on the microtubule end can contribute to the frequency of catastrophe

Microtubules are dynamic polymers of αβ-tubulin that have essential roles in chromosome segregation and organization of the cytoplasm. Catastrophe-the switch from growing to shrinking-occurs when a microtubule loses its stabilizing GTP cap. Recent evidence indicates that the nucleotide on the microtubule end controls how tightly an incoming subunit will be bound (trans-acting GTP), but most current models do not incorporate this information. We implemented trans-acting GTP into a computational model for microtubule dynamics. In simulations, growing microtubules often exposed terminal GDP-bound subunits without undergoing catastrophe. Transient GDP exposure on the growing plus end slowed elongation by reducing the number of favorable binding sites on the microtubule end. Slower elongation led to erosion of the GTP cap and an increase in the frequency of catastrophe. Allowing GDP-to-GTP exchange on terminal subunits in simulations mitigated these effects. Using mutant αβ-tubulin or modified GTP, we showed experimentally that a more readily exchangeable nucleotide led to less frequent catastrophe. Current models for microtubule dynamics do not account for GDP-to-GTP exchange on the growing microtubule end, so our findings provide a new way of thinking about the molecular events that initiate catastrophe.
Post-mastectomy breast reconstruction and its subsequent complications: a comparison between obese and non-obese women with breast cancer

To compare the utilization pattern of breast reconstruction between obese and non-obese patients and assess the association between obesity and postoperative complications as well as healthcare costs. Using MarketScan databases, we identified 2558 breast cancer patients who underwent mastectomy between 2009 and 2012. Temporal trends in breast reconstruction were assessed using the Cochran–Armitage test. Logistic regression models were performed to determine the association between obesity and the occurrence of postoperative complications. Healthcare costs were compared using a generalized linear model. Among 2558 patients treated with mastectomy, the breast reconstruction rate of non-obese patients (76.2 %) was significantly higher than patients in obese class I and class III P < 0.001). Compared with non-obese patients, obese patients had significantly higher rates of infection (OR 1.53, for obese class I, and OR 1.60, for obese class III P < 0.001). Our analysis demonstrated a significant gap in breast reconstruction between obese and non-obese patients, and our finding underscores the need for careful preoperative assessment of obese patients and call for additional research to minimize the risk of complications.
THE EFFECT OF DIVORCE ON FATHERS: AN OVERVIEW OF THE LITERATURE

Divorce is becoming a major mental health problem in the United States. With rare exception psychological attention has usually focused on the effect of divorce on children and mothers. The author suggests that as some fathers become more involved in family nurturing they will be more intensely affected by marital disruption, particularly as it involves changes in the relationship to their children. A review of the recent psychological literature on divorce and custody is presented as a framework for understanding the divorcing father who is requesting psychiatric help.
A robust one class Bayesian approach for masquerade detection

Masquerade attack is a serious computer security problem, which can cause significant damage. Many previous research works were based on two-class training that collected data from multiple users to train one self (i.e., regular) model and one non-self (i.e., abnormal) model for each user. Two-class learning methods for masquerade detection can generate accurate results but demand data from all users, which may not be available for many practical applications. On the other side, one-class learning methods build a model for each user by utilizing only his/her own data. One-class learning methods are more practical but they also suffer from the limited amount of training information from a single user. To address the data sparsity issue, we propose a robust one-class Bayesian approach for masquerade detection. The new method explicitly considers model uncertainty by integrating out the unknown model parameters for generating robust results, while previous one-class methods only use a single point estimate to find an optimal model. We derive the full analytical solution of the predictive distribution over all possible model parameters. A set of experimental results demonstrate that the proposed approach outperforms most previous one-class approach for masquerade detection.
Caenorhabditis elegans as a Model to Study the Molecular and Genetic Mechanisms of Drug Addiction

Drug addiction takes a massive toll on society. Novel animal models are needed to test new treatments and understand the basic mechanisms underlying addiction. Rodent models have identified the neurocircuitry involved in addictive behavior and indicate that rodents possess some of the same neurobiologic mechanisms that mediate addiction in humans. Recent studies indicate that addiction is mechanistically and phylogenetically ancient and many mechanisms that underlie human addiction are also present in invertebrates. The nematode Caenorhabditis elegans has conserved neurobiologic systems with powerful molecular and genetic tools and a rapid rate of development that enables cost-effective translational discovery. Emerging evidence suggests that C. elegans is an excellent model to identify molecular mechanisms that mediate drug-induced behavior and potential targets for medications development for various addictive compounds. C. elegans emit many behaviors that can be easily quantitated including some that involve interactions with the environment. Ethanol (EtOH) is the best-studied drug-of-abuse in C. elegans and at least 50 different genes/targets have been identified as mediating EtOH's effects and polymorphisms in some orthologs in humans are associated with alcohol use disorders. C. elegans has also been shown to display dopamine and cholinergic system-dependent attraction to nicotine and demonstrate preference for cues previously associated with nicotine. Cocaine and methamphetamine have been found to produce dopamine-dependent reward-like behaviors in C. elegans. These behavioral tests in combination with genetic/molecular manipulations have led to the identification of dozens of target genes/systems in C. elegans that mediate drug effects. The one target/gene identified as essential for drug-induced behavioral responses across all drugs of abuse was the cat-2 gene coding for tyrosine hydroxylase, which is consistent with the role of dopamine neurotransmission in human addiction. Overall, C. elegans can be used to model aspects of drug addiction and identify systems and molecular mechanisms that mediate drug effects. The findings are surprisingly consistent with analogous findings in higher-level organisms. Further, model refinement is warranted to improve model validity and increase utility for medications development.
Observations on the current status of poison control centers in the United States.

The history, effectiveness, and services of regional poison control centers are reviewed. In addition, the American Association of Poison Control Centers’ critera for designation as a regional poison control center are presented.
Nickel and Iron Pincer Complexes as Catalysts for the Reduction of Carbonyl Compounds

ConspectusThe reductions of aldehydes, ketones, and esters to alcohols are important processes for the synthesis of chemicals that are vital to our daily life, and the reduction of CO2 to methanol is expected to provide key technology for carbon management and energy storage in our future. Catalysts that affect the reduction of carbonyl compounds often contain ruthenium, osmium, or other precious metals. The high and fluctuating price, and the limited availability of these metals, calls for efforts to develop catalysts based on more abundant and less expensive first-row transition metals, such as nickel and iron. The challenge, however, is to identify ligand systems that can increase the thermal stability of the catalysts, enhance their reactivity, and bypass the one-electron pathways that are commonly observed for first-row transition metal complexes. Although many other strategies exist, this Account describes how we have utilized pincer ligands along with other ancillary ligands to accomplish these goa...