cssi/SciSciGPT-SciSciNet huggingface dataset:
Fine-grained network time synchronization using reference broadcasts

Recent advances in miniaturization and low-cost, low-power design have led to active research in large-scale networks of small, wireless, low-power sensors and actuators. Time synchronization is critical in sensor networks for diverse purposes including sensor data fusion, coordinated actuation, and power-efficient duty cycling. Though the clock accuracy and precision requirements are often stricter than in traditional distributed systems, strict energy constraints limit the resources available to meet these goals.We present Reference-Broadcast Synchronization, a scheme in which nodes send reference beacons to their neighbors using physical-layer broadcasts. A reference broadcast does not contain an explicit timestamp; instead, receivers use its arrival time as a point of reference for comparing their clocks. In this paper, we use measurements from two wireless implementations to show that removing the sender's nondeterminism from the critical path in this way produces high-precision clock agreement (1.85 ± 1.28μsec, using off-the-shelf 802.11 wireless Ethernet), while using minimal energy. We also describe a novel algorithm that uses this same broadcast property to federate clocks across broadcast domains with a slow decay in precision (3.68 ± 2.57μsec after 4 hops). RBS can be used without external references, forming a precise relative timescale, or can maintain microsecond-level synchronization to an external timescale such as UTC. We show a significant improvement over the Network Time Protocol (NTP) under similar conditions.
The significance of nasal carriage of Staphylococcus aureus and the incidence of postoperative wound infection

Staphylococcus aureus infections are associated with considerable morbidity and, in certain situations, mortality. The association between the nasal carriage of S. aureus and subsequent infection has been comprehensively established in a variety of clinical settings, in particular, patients undergoing haemodialysis and continuous ambulatory peritoneal dialysis (CAPD), and in patients undergoing surgery. Postoperative wound infections are associated with a high degree of morbidity and represent an important medical issue. Until recently, eradication of S. aureus nasal carriage by various topical and systemic agents had proved unsuccessful. Mupirocin is a novel topical antibiotic with excellent antibacterial activity against staphylococci. Recent studies have demonstrated that intranasal administration of mupirocin is effective in eradicating the nasal carriage of S. aureus and in reducing the incidence of S. aureus infections in haemodialysis and CAPD patients. It has been suggested that sufficient evidence now exists to test the hypothesis that eradication of the carrier state in surgical patients preoperatively may reduce the incidence of S. aureus postoperative wound infections.
A Catalog of Background Stars Reddened by Dust in the Taurus Dark Clouds

Normal field stars located behind dense clouds are a valuable resource in interstellar astrophysics, as they provide continua in which to study phenomena such as gas-phase and solid-state absorption features, interstellar extinction, and polarization. This paper reports the results of a search for highly reddened stars behind the Taurus Dark Cloud complex. We use the Two Micron All Sky Survey (2MASS) Point Source Catalog to survey a � 50 deg 2 area of the cloudtoalimitingmagnitudeof Ks ¼ 10:0.Photometryinthe1.2Y2.2 � mpassbandsfrom2MASSiscombinedwith photometry at longer infrared wavelengths (3.6Y12 � m) from the Spitzer Space Telescope and the Infrared Astronomical Satellite to provide effective discrimination between reddened field stars and young stellar objects (YSOs) embedded in the cloud. Our final catalog contains 248 confirmed or probable background field stars, together with estimatesof their total visualextinctions,which spanthe range2 5 � m. Subject headingg dust, extinction — infrared: stars — ISM: clouds — ISM: individual (Taurus Dark Cloud)
Feasibility studies of a compact mm-wave linac FEL

Abstract Microfabrication technology offers an alternative method for fabricating precision, miniature-size components suitable for use in accelerator physics and commercial applications. The orginal R&D work at Argonne, in collaboration with the University of Illinois at Chicago and University of Wisconsin-Madison, has produced encouraging results in the area of rf accelerating structure design, optical and X-ray masks production, deep X-ray lithography (LIGA exposures), and precision structural alignments. In this paper we present feasibility studies for a compact single pass mm-linac FEL to produce short wavelength radiation. This system will consist of a photocathode rf gun operated at 30 GHz, a 50-MeV superconducting constant gradient structure operated at 60 GHz, and a microundulator with 1-mm period.
The Circuits and Robust Design Methodology of the Massively Parallel Processor Based on the Matrix Architecture

Novel circuits and design methodology of the massively parallel processor based on the matrix architecture are introduced. A fine-grained processing elements (PE) circuit for high-throughput MAC operations based on the Booth's algorithm enhances the performance of a 16-bit fixed-point signed MAC, which operates up to 30.0GOPS/W. The dedicated I/O interface circuits are designed for converting the direction of data access and supporting the interleaved memory architecture, and they are implemented for maximizing the processor core efficiency. Power management techniques for suppressing current peaks and reducing average power consumption are proposed to enhance the robustness of the macro. The circuits and the design methodology proposal in this paper are attractive for achieving a high performance and robust massively parallel SIMD processor core employed in multimedia SoCs
A Comprehensive Analysis of Poverty in India

This paper offers a comprehensive analysis of poverty in India. It shows that regardless of which of the two official poverty lines the authors use, they see a steady decline in poverty in all states and for all social and religious groups. Accelerated growth between fiscal years 20042005 and 2009-2010 also led to an accelerated decline in poverty rates. Moreover, the decline in poverty rates during these years has been sharper for the socially disadvantaged groups relative to upper caste groups so that the authors now observe a narrowing of the gap in the poverty rates between the two sets of social groups. The paper also provides a discussion of the recent controversies in India regarding the choice of poverty lines.
An improved and facile preparation of ω-SF5-(perfluoroethyl)benzene (SF5CF2CF2C6H5)

Abstract A high-yield preparation of SF 5 CF 2 CF 2 C 6 H 5 has been achieved via a two-step process: α,β,β-trifluorostyrene reacts with SF 5 Br to give the intermediate product SF 5 CF 2 CFBrC 6 H 5 ( 1 ) which, when treated with AgBF 4 in methylene chloride, produces SF 5 CF 2 CF 2 C 6 H 5 ( 2 ) in high yield.
Migration and Inequality in Xinjiang: A Survey of Han and Uyghur Migrants in Urumqi

This paper seeks to contribute to the literature on Han-Uyghur inequality by comparing Han and Uyghur migrants in Urumqi, Xinjiang. Drawing from a survey of 30 sites of service activities and approximately 600 respondents in Urumqi, conducted in 2008, the authors argue that in addition to state-orchestrated migration that has been considered a source of Han-Uyghur inequality, it is also important to pay attention to the role of self-initiated migration. Through descriptive and statistical analyses of migrants' demographic, human-capital, employment, and migration characteristics, they find that Uyghur migrants do not seem disadvantaged compared to Han migrants. The findings underscore the heterogeneity of Urumqi's labor market, the role of economic reforms that motivate migration within and to Xinjiang, and the complexity of Han-minority inequality.
From Young and Hot to Old and Cold: Comparing White Dwarf Cooling Theory to Main Sequence Stellar Evolution in Open Clusters

I explore the current ability of both white dwarf cooling theory and main sequence stellar evolution theory to accurately determine stellar population ages by comparing ages derived using both techniques for open clusters ranging from 0.1 to 4 Gyr. I find good agreement between white dwarf and main sequence evolutionary ages over the entire age range currently available for study. I also find that directly comparing main sequence turn-off ages to white dwarf ages is only weakly sensitive to realistic levels of errors in cluster distance, metallicity, and reddening. Additional detailed comparisons between white dwarf and main sequence ages have tremendous potential to refine and calibrate both of these important clocks, and I present new simulations of promising open cluster targets. The most demanding requirement for these white dwarf studies are very deep (V � 25–28) cluster observations made necessary by the faintness of the oldest white dwarfs.
Inflation Targeting and Exchange Rate Regimes: Evidence from the Financial Markets*

Inflation targeting is gaining popularity as a framework for conducting monetary policy. At the same time many countries employ some sort of foreign exchange intervention policy assuming that these two policies can coexist. This paper attempts to show that both policies are not sustainable. Israel is a classic test case. We test our hypothesis using information from the financial markets. The results support the hypothesis that both policies cannot be sustained in the long run. The conclusion is that a credible monetary policy aimed at inflation targets should be conducted in a free floating exchange rate regime.
Optimal Sizing of Voltage Control Devices for Distribution Circuit with Intermittent Load

We consider joint control of a switchable capacitor and a D-STATCOM for voltage regulation in a distribution circuit with intermittent load. The control problem is formulated as a two-timescale optimal power flow problem with chance constraints, which minimizes power loss while limiting the probability of voltage violations due to fast changes in load. The control problem forms the basis of an optimization problem which determines the sizes of the control devices by minimizing sum of the expected power loss cost and the capital cost. We develop computationally efficient heuristics to solve the optimal sizing problem and implement real-time control. Numerical experiments on a circuit with high-performance computing (HPC) load show that the proposed sizing and control schemes significantly improve the reliability of voltage regulation on the expense of only a moderate increase in cost.
Measurements and Calculations of Halfraum Radiation Drives at the Omega Laser

Abstract Thin-walled gold halfraums are a common choice for producing X-ray drives in experiments at high-power laser facilities. At the Omega Laser, we use 10 kJ of laser energy in a two-pulse sequence to generate halfraum drive temperatures of 160–190 eV for ∼3 ns. This type of drive is well characterized and reproducible, with characterization of the drive radiation temperature typically performed using the Dante diagnostic, a 10-channel array of filtered X-ray diodes. Additionally, photoconductive diamond detectors (PCDs) have been calibrated to the Dante, and can now be used in place of the Dante to measure the drive. Measurements of halfraum drives from both Dante and PCDs are compared with calculations, with good agreement. This agreement lends the calculations a predictive capability in designing further experiments utilizing halfraum drives.
Back flips with a hexapedal robot

We report on the design and analysis of a controller which can achieve dynamical self-righting of our hexapedal robot, RHex. We present an empirically developed control procedure which works reasonably well on indoor surfaces, using a hybrid energy pumping strategy to overcome torque limitations of its actuators. Subsequent modeling and analysis yields a new controller with a much wider domain of success as well as a preliminary understanding of the necessary hybrid control strategy. Simulation results demonstrate the superiority of the improved control strategy to the first generation empirically designed controller.
Singular Direction Avoidance Steering for Control-Moment Gyros

A new form of the equations of motion for a spacecraft with Single Gimbal Control Moment Gyros is developed using a momentum approach. This set of four vector equations describing the rotational motion of the system is of order 2N + 7 where N is the number of CMGs. The control input is an N x I column vector of torques applied to the gimbal axes. A modification to the singularity robust Lyapunov control law presented by Oh and Vadali is examined and compared to their control law. Specifically, the attempt to avoid singular gimbal configurations is abandoned in favor of simply avoiding movement in the singular direction. The singular value decomposition is used to compute a pseudoinverse which prevents large gimbal rate commands near or at actual singularities.
The complexity of distributed concurrency control

We present a formal framework for distributed databases, and we study the complexity of the concurrency control problem in this framework. Our transactions are partially ordered sets of actions, as opposed to the straight-line programs of the centralized case. The concurrency control algorithm, or scheduler, is itself a distributed program. Three notions of performance of the scheduler are studied and interrelated: (1) its parallelism, (2) the computational complexity of the problems it needs to solve and (3) the cost of communication between the various parts of the scheduler. We show that the number of messages necessary and sufficient to support a given level of parallelism is equal to the minimax value of a combinatorial game. We show that this game is PSPACE-complete. It follows that, unless $\text{NP} = \text{PSPACE}$, a scheduler cannot simultaneously minimize communication and be computationally efficient. This result, we argue, captures the quantum jump in complexity of the transition from centra...
New Evidence on the Valuation Effects of Convertible Bond Calls

This study examines the wealth effects of convertible bond call announcements on stockholders, straight bondholders, and called and non-called convertible debtholders. We document that forced conversions are associated with a significant loss in firm value. The results suggest that convertible call announcements can trigger both negative signal and wealth transfer effects. We show that at least part of the negative effect on stock prices results from wealth transfer to straight bondholders. Our analysis also lends empirical validity to the common contention that called convertible bondholders suffer wealth expropriation due to the elimination of the premium. The wealth effect on non-called convertible debtholders is insignificant. Cross-sectional analysis reveals that the negative signal effect is important in explaining bond, stock, and firm excess returns. Finally, we present evidence that refutes the notion that bonds are called to relieve the firm from restrictive debt covenants.
Markup cycles, dynamic misallocation, and amplification

Abstract We develop a tractable dynamic general equilibrium model of oligopolistic competition with a continuum of heterogeneous industries. Industries are exposed to aggregate and industry-specific productivity shocks. Firms in each industry set value-maximizing state-contingent markups, taking as given the behavior of all other industries. When consumers are risk-averse, industry markups are countercyclical with regards to the industry-specific component, but may be procyclical with regards to the aggregate shock. The general equilibrium dispersion of markups implied by the optimization of heterogeneous industries creates misallocation of labor across industries. The misallocation, in turn, generates aggregate welfare losses state-by-state that feed back into the industry problem via a representative agent's marginal utility of aggregate consumption. Misallocation dynamics may transmit industry-specific shocks, or amplify small aggregate shocks, and so lead to aggregate fluctuations through these feedback effects.
Economic Openness and Territorial Politics in China

Why and how has the Chinese central government so far managed to fend off the centrifugal forces under rising globalization that are predicted to undermine national-level political authority everywhere? When institutionally empowered by centralized governing political parties as in China, national politicians confronting the menace of economic openness will resort to exercising tighter political control over the subnational governments of the 'winner' regions in the global markets. Although its goal is to facilitate revenue extraction, redress domestic economic disparity, and prolong the rule of national leaders, regionally targeted central political control could engender mixed economic consequences. Sheng examines the political response of the Chinese central government, via the ruling Chinese Communist Party, to the territorial challenges of the country's embrace of the world markets, and the impact of the regionally selective exercise of political control on central fiscal extraction and provincial economic growth during the 1978–2005 period.
Developing Young Space System Engineers

At a fundamental level, system engineering is the process by which engineering efforts are communicated, controlled, and organized on complex projects. The engineers who perform this work well are able to work across multiple engineering and managerial disciplines. They require outstanding technical, personal, management, and communications skills and an ability, based on experience, to work in areas where clean decisions are not possible. Furthermore, within the Space Department (SD) at the Johns Hopkins University - Applied Physics Laboratory (JHU/APL), lead system engineers are delegated responsibility for leading the development of the technical baselines and ensuring their performance robustly meets requirements. Success in these areas requires a level of capability and maturity that can only be developed through time and experience. With such a high bar being set, the question: “How does one develop high-caliber system engineers?” becomes difficult to answer. Within the JHU/APL SD, prior to 2006, the primary means of attaining system engineers were through hiring experienced staff from external organizations or moving interested and capable staff from other areas of the department. This situation creates two problems within a growing organization. First, potential staff with the credentials stated above is extremely difficult to find, making it difficult for a system engineering organization to grow in the face of attrition. Second, the demographics of a system engineering organization become skewed toward older staff, limiting the organization's access to new methodologies, alternative means of collaboration, linkages to the university system and (frankly) youthful energy, to name a few. To address this need, management within the department developed a program for developing newly minted Masters Graduates. Key to this program is the recognition that system engineering is a process for communicating and organizing the work associated with the development and production of a specific product which is not an end to itself. As such, providing experience in both system engineering and the product-focused disciplines necessary for developing, integrating or operating space systems is critical. This describes the impetus for developing the Young Space Systems Engineers Program, key program features, problems encountered during development, and the program's successes. A strong case is made for the necessity for system engineers to understand the system engineering process and the product they produce, as well as the human element that goes into making it.
Growth patterns and regime change in nationally shared electronic banking networks: an econometric analysis of CIRRUS and PLUS

The authors examine whether adoption of shared electronic banking network technology in the financial services industry exhibits S-curve growth patterns as other technologies do. They consider this issue in an econometric analysis of the national networks CIRRUS and PLUS. When the size of the CIRRUS and PLUS networks grew into the range of market saturation, network operators decided in favor of 'duality', a move to share their assets, while maintaining separate corporate identities. This research offers empirical evidence that it may be necessary to formulate more sophisticated models to describe the process of adoption and diffusion of an innovation in the presence of market competition. >
eNcentive: a framework for intelligent marketing in mobile peer-to-peer environments

In recent years, the growth of Mobile Computing, Electronic Commerce and Mobile Electronic Commerce has created a new concept of Mobile Electronic Marketing. New marketing models are being developed and used to target mobile users. Mobile environments introduces new challenges that need to be overcome by these marketing models in order to be successful and effective. This paper proposes a framework, called eNcentive, which addresses many of the issues that are characteristic of mobile environments. eNcentive facilitates peer-to-peer electronic marketing in mobile ad hoc environments. Our framework employs a intelligent marketing scheme, by providing users the capability to collect information like sales promotions and discounts. Users can propagate this marketing information to other users in the network. Participating users benefit from such circulation since businesses that originally created the promotions reward the active distributors with additional promotions and other compensations.
XBRL Tagging of Financial Statement Data Using XMLSpy: The Small Company Case

ABSTRACT: Publicly traded companies in the U.S. are required by the Securities and Exchange Commission (SEC) to file their financial statement data using XBRL tags. Other countries using international accounting standards have adopted similar XBRL filing requirements. This case provides a brief introduction to XBRL for business or accounting majors, and uses freely available software products (Altova XMLSpy) and training tools that help learners quickly progress through a basic introduction to XML (the foundation for XBRL), the XBRL taxonomy schema, and actual tagging of financial statement numbers. The basic skills learned in this case give accountants and other business professionals a working knowledge of how XBRL and other XML-based business documents are and can be used in practice. The case also raises awareness of the XBRL taxonomy development bodies, filing repositories, and development tools available in this domain for those interested in pursuing this technology in more detail.
Strategic approximations of discontinuous games

An infinite game is approximated by restricting the players to finite subsets of their pure strategy spaces. A strategic approximationof an infinite game is a countable subset of pure strategies with the property that limits of all equilibria of all sequences of approximating games whose finite strategy sets eventually include each member of the countable set must be equilibria of the infinite game. We provide conditions under which infinite games admit strategic approximations.
Building the TeraGrid

On 1 October 2004, the most ambitious high-performance Grid project in the United States-the TeraGrid-became fully operational. Resources at nine sites--the San Diego Supercomputer Center, the California Institute of Technology, the National Center for Supercomputing Applications, the University of Chicago/Argonne National Laboratory, Pittsburgh Supercomputing Center, Texas Advanced Computing Center, Purdue University, Indiana University and Oak Ridge National Laboratory-were joined via an ultra-fast optical network, unified policies and security procedures and a sophisticated distributed computing software environment. Funded by the National Science Foundation, the TeraGrid enables scientists and engineers to combine distributed, multiple data sources with computation at any of the sites or link massively parallel computer simulations to extreme-resolution visualizations at remote sites. A single shared utility lets multiple resources be easily leveraged and provides improved access to advanced computational capabilities. One of the demonstrations of this new model for using distributed resources, Teragyroid, linked the infrastructure of the TeraGrid with computing resources in the United Kingdom via a transatlantic data fibre link. Once connected, the software framework of the RealityGrid project was used to successfully explore lattice-Boltzmann simulations involving lattices of over one billion sites.
Spillover Effects in Subjective Performance Evaluation: Bias and the Asymmetric Influence of Controllability

ABSTRACT: We examine how subjective performance evaluations are influenced by the level and controllability of an accompanying measure of a separate performance dimension. In our experiment, supervisors evaluate the office administration performance of a hypothetical subordinate. We find that supervisors' subjective evaluations are directionally influenced by an accompanying objective measure of sales performance, even after excluding participants who perceive informativeness across measures. Consistent with concerns for fairness and motivation, we also find an asymmetric uncontrollability effect—supervisors' evaluations are higher when an uncontrollable factor decreases the subordinate's sales (i.e., they compensate for bad luck), but are not lower when the uncontrollable factor increases the subordinate's sales (i.e., they do not punish for good luck). This evidence suggests that supervisors use discretion provided to evaluate performance on one task to adjust for perceived deficiencies in the evaluatio...
StReAm: object-oriented programming of stream architectures using PAM-Blox

General-purpose microprocessors are designed to deliver low-latency computation with maximal clock frequencies, leading to high power consumption. In terms of performance and power consumption, latency-tolerant applications can be efficiently implemented with architectures that provide high throughputs, such as Imagine, Score, RaPiD, and the PCI-PipeRench. Stream architectures are fully-pipelined, high-throughput microarchitectures. Algorithms are executed by mapping dataflow graphs to hardware and streaming the data through the architecture. In the best case, when all the loops are fully unrolled, the dataflow graph is acyclic and the clock frequency of the design is the data rate. In this paper, we develop a domain-specific compiler for programming FPGAs, called StReAm. StReAm is build on top of the module generation environment PAM-Blox.
Object schemas for grounding language in a responsive robot

An approach is introduced for physically grounded natural language interpretation by robots that reacts appropriately to unanticipated physical changes in the environment and dynamically assimilates new information pertinent to ongoing tasks. At the core of the approach is a model of object schemas that enables a robot to encode beliefs about physical objects in its environment using collections of coupled processes responsible for sensorimotor interaction. These interaction processes run concurrently in order to ensure responsiveness to the environment, while co-ordinating sensorimotor expectations, action planning and language use. The model has been implemented on a robot that manipulates objects on a tabletop in response to verbal input. The implementation responds to verbal requests such as 'Group the green block and the red apple', while adapting in real time to unexpected physical collisions and taking opportunistic advantage of any new information it may receive through perceptual and linguistic channels.
Single-chip microcomputers can be easy to program

Most single-chip microcomputers (MCUs) use the split-memory Harvard architecture. A few single-chips trace their architectural heritage to large computers due to the common-memory Von Neumann organization. The major differences are that a Harvard-based MCU costs less in its undistorted form, and a Von Neumann-based MCU is more expandable and easier to program.Since the traits of Harvard-based single-chips are quite well known, though perhaps not by that name, the focus is placed on the programming benefits of a Von Neumann MCU. Programming costs can be lowered while increasing program reliability. Data organizations can be more flexible in both RAM and ROM. Program changes can be incorporated more quickly. The generalized instruction set is easier to understand. The M6805 family of MCUs is used to illustrate these benefits.
Aquaporin water channels (Nobel Lecture).

Thank you very much. I am humbled, I am delighted; I am honored. It is every scientist s dream to give the Nobel Lecture in Stockholm. But I would not be honest if I did not tell you that I am having a little anxiety being on this platform. I have lectured a number of times in Sweden, and I thought I would share with you some events preceding a special lecture that I gave here a few years ago. Arriving at Arlanda Airport, I waited in line at the Passport Control behind a group of businessmen in suits with briefcases. I heard the first in line asked by the control officer to state the purpose of his visit to Sweden. When the man replied “business,” the officer approved and stamped his passport. One at a time, each stepped forward and was asked the same thing; each answered “business” and was approved. Eventually it was my turn, and I was dressed in rumpled clothes after spending the night in the Economy Minus section of an SAS jetliner. The officer asked me the purpose of my visit, and I said “I am here to give the von Euler Lecture at Karolinska Institute.” The officer immediately looked up, stared at me, and asked, “Are you nervous?” At that point I became intensely nervous and said “Yes, I am a little nervous.” The officer looked up again and stated “Well, you should be!” So if the lecturers look a little nervous, the problem is at Arlanda.
High‐Density Yttria for Practical Ceramic Applications

This paper describes a process by which highly reactive yttria powder can be sintered to high density at a relatively low firing temperature to form a variety of useful ceramic items. The process utilizes an aqueous polymer to precipitate a yttrium precursor. The yttrium precursor is thermally treated to form a friable oxide ash. After a double-calcination-grind procedure, high-density yttria items such as substrates, crucibles, and nozzles can be fabricated.
Regulation of Neuregulin-Mediated Acetylcholine Receptor Synthesis by Protein Tyrosine Phosphatase SHP2

Synapse-specific expression of the nicotinic acetylcholine receptor (AChR) is believed to be mediated by neuregulin, an epidermal growth factor-like trophic factor released by somatic motoneurons at the neuromuscular junction (NMJ). Neuregulin stimulates ErbB2, ErbB3, and ErbB4, members of the ErbB family of receptor tyrosine kinases. SHP2 is a cytoplasmic protein tyrosine phosphatase containing two Src homology 2 domains near its N terminus, and has been shown to be a positive mediator of mitogenic responses to various growth factors. We found that SHP2 interacted with ErbB2 and ErbB3 after neuregulin stimulation of muscle cells. Expression of SHP2 in C2C12 mouse muscle cells attenuated the neuregulin-induced expression of an AChR epsilon-promoter reporter gene, whereas a catalytically inactive SHP2 mutant or a mutant lacking the N-terminal Src homology 2 (SH2) domain enhanced reporter expression, suggesting that SHP2 negatively regulates the neuregulin signaling pathway. In fibroblast cells that express a mutant SHP2 with a targeted deletion of the N-terminal SH2 domain, neuregulin-mediated activation of the Ras/Raf/extracellular signal-regulated kinase cascade was enhanced. Furthermore, we found that SHP2 immunoreactivity colocalized with the staining of alpha-bungarotoxin, a marker of the NMJ. These results demonstrate a negative role of SHP2 in the neuregulin signal that leads to AChR gene expression at the NMJ.
OPTIMAL TAXATION IN THE PRESENCE OF BAILOUTS

The termination of a representative financial firm due to excessive leverage may lead to substantial bankruptcy costs. A government in the tradition of Ramsey (1927) may be inclined to provide transfers to the firm so as to prevent its liquidation and the associated deadweight costs. It is shown that the optimal taxation policy to finance such transfers exhibits procyclicality and history dependence, even in a complete market. These results are in contrast with pre-existing literature on optimal fiscal policy, and are driven by the endogeneity of the transfer payments that are required to salvage the financial firm.
Chaos and Mixing in Triaxial Stellar Systems

We investigate the timescales for stochasticity and chaotic mixing in a family of triaxial potentials that mimic the distribution of light in elliptical galaxies. Some of the models include central point masses designed to represent nuclear black holes. Most of the boxlike orbits are found to be stochastic, with mean Liapunov times that are 3 − 6 times the period of the long-axis orbit. In models with large cores or small black holes, the stochastic orbits mimic regular box orbits for hundreds of oscillations at least. However a small core radius or significant black hole mass causes most of the stochastic orbits to diffuse through phase space on the same timescale, visiting a significant fraction of the volume beneath the equipotential surface. Some stochastic orbits, with initial conditions lying close to those of regular orbits, remain trapped in all models. We estimate timescales for chaotic mixing in the more strongly stochastic models by evolving ensembles of 10 4 points until their distribution reaches a nearly steady state. Mixing initially takes place rapidly, with characteristic times of 10 − 30 dynamical times, as the phase points fill a region similar in shape to that of a box orbit. Subsequent mixing is slower, with characteristic times of hundreds of orbital periods. Mixing rates were found to be enhanced by the addition of modest force perturbations, and we propose that the stochastic parts of phase space might be efficiently mixed during the early phases of galaxy formation when such perturbations are large. The consequences for the structure and evolution of elliptical galaxies are discussed.
A self-consistent derivation of ion drag and Joule heating for atmospheric dynamics in the thermosphere

The thermosphere is subject to additional elec- tric and magnetic forces, not important in the middle and lower atmosphere, due to its partially ionized atmosphere. The effects of charged particles on the neutral atmospheric dynamics are often parameterized by ion drag in the mo- mentum equations and Joule heating in the energy equation. Presented in this paper are a set of more accurate parame- terizations for the ion drag and Joule heating for the neutral atmosphere that are functions of the difference between bulk ion velocity and neutral wind. The parameterized expres- sions also depend on the magnetic field, the Pedersen and Hall conductivities, and the ratio of the ion cyclotron fre- quency to the ion-neutral collision frequency. The formal re- lationship between the electromagnetic energy, atmospheric kinetic energy, and Joule heating is illustrated through the conversion terms between these three types of energy. It is shown that there will always be an accompanying conver- sion of kinetic energy into Joule heating when electromag- netic energy is generated through the dynamo mechanism of the atmospheric neutral wind. Likewise, electromagnetic en- ergy cannot be fully converted into kinetic energy without producing Joule heating in the thermosphere. in the momentum equations (ion drag), and an energy con- version term in the thermal energy equation (Joule heating) actualized by the neutral wind. Though the concentrations of the charged particles are far less than those of the neutral at- mosphere in the thermosphere below 1000 km (e.g., Kelley, 1989, Appendix B) they impose a non-negligible ion drag and a Joule heating because the charged particles experienc- ing the electromagnetic forces may move in a significantly different direction and magnitude than the neutral wind.
Interfacing the environment: Networked screens and the ethics of visual consumption

The screen continues to be the primary generator of visual imagery in contemporary culture, including of the natural world. This paper examines the screen as visual interface in the construction and consumption of physical environments. Screens are increasingly incorporated in our daily habits and imbricated into our lives, especially as mediating technologies are embedded into the surfaces of our physical surroundings, shaping and molding our interactions with and perceptions of those environments. As screens become increasingly portable and digitized, they further modify our relationships with environments, projecting multiple images and imagery which fracture and layer visual consumption. And as screens become ubiquitous in urban environments, they network into maps of information control and consumption. We need to fully understand these processes of screen-mediated representation and interaction in order to be able to comment on the ethics of contemporary practices of visually consuming physical environments. In particular, the paper will argue that processes of consumption and their interaction with visual interfacing technologies are not simple or straight-forward, but nevertheless pose ethical questions about the relationship between visual and material circuits of consumption.
The rigid relation principle, a new weak choice principle

The rigid relation principle, introduced in this article, asserts that every set admits a rigid binary relation. This follows from the axiom of choice, because well-orders are rigid, but we prove that it is neither equivalent to the axiom of choice nor prov- able in Zermelo-Fraenkel set theory without the axiom of choice. Thus, it is a new weak choice principle. Nevertheless, the restric- tion of the principle to sets of reals (among other general instances) is provable without the axiom of choice. In this article we introduce the rigid relation principle (RR), which asserts that every set admits a rigid binary relation, or equivalently, that every set is the vertex set of a rigid directed graph. To be precise, RR asserts that for every set A there is a binary relation R on A such that the structure hA,Ri is rigid, meaning that it has no nontrivial automorphisms, that is, no bijective function � : A → A such that a R b ⇐⇒ �(a) R �(b), other than the identity function. The RR principle follows easily from the axiom of choice, because under AC every set A has a well-order <, and it is easy to see that well- orders are rigid: if a bijection � : A → A is <-preserving, then there can be no <-minimal element a for which �(a) 6 a, and sois the identity function. Nevertheless, we shall prove that RR is not equivalent to AC, and neither is it provable in ZF, assuming ZF is consistent. Thus, it is a weak choice principle. Main Theorem 1. The rigid relation principle RR is a weak choice principle in the sense that it is a consequence of the axiom of choice, but not equivalent to it, assuming ZF is consistent, and neither is it provable in ZF alone. Nevertheless, the restriction of RR to sets of reals (among other general instances) is provable in ZF.
Endo-Selective Enyne Ring-Closing Metathesis Promoted by Stereogenic-at-W Mono-Pyrrolide Complexes

The utility of W-alkylidene complexes for enyne ring-closing metathesis is demonstrated in a direct comparison with Mo-based analogs. Tungsten complexes lead to less alkyne oligomerization and higher levels of endo-selectivity and enantioselectivity.
Fixing the functoriality of Khovanov homology

We describe a modification of Khovanov homology [13], in the spirit of Bar-Natan [2], which makes the theory properly functorial with respect to link cobordisms. This requires introducing “disorientations” in the category of smoothings and abstract cobordisms between them used in Bar-Natan’s definition. Disorientations have “seams” separating oppositely oriented regions, coming with a preferred normal direction. The seams satisfy certain relations (just as the underlying cobordisms satisfy relations such as the neck cutting relation). We construct explicit chain maps for the various Reidemeister moves, then prove that the compositions of chain maps associated to each side of each of Carter, Rieger and Saito’s movie moves [8; 7] always agree. These calculations are greatly simplified by following arguments due to Bar-Natan and Khovanov, which ensure that the two compositions must agree, up to a sign. We set up this argument in our context by proving a result about duality in Khovanov homology, generalising previous results about mirror images of knots to a “local” result about tangles. Along the way, we reproduce Jacobsson’s sign table [10] for the original “unoriented theory”, with a few disagreements.
The topology of Birkhoff varieties

Our main theorem is that the inclusion of any Birkhoff subvariety in an affine flag variety is a homotopy equivalence. We also construct analogues of tubular neighborhoods for Birkhoff and Schubert varieties in affine or classical flag varieties.
Gravitational and electroweak unification by replacing diffeomorphisms with larger group

The covariance group for general relativity, the diffeomorphisms, is replaced by a group of coordinate transformations which contains the diffeomorphisms as a proper subgroup. The larger group is defined by the assumption that all observers will agree whether any given quantity is conserved. Alternatively, and equivalently, it is defined by the assumption that all observers will agree that the general relativistic wave equation describes the propagation of light. Thus, the group replacement is analogous to the replacement of the Lorentz group by the diffeomorphisms that led Einstein from special relativity to general relativity, and is also consistent with the assumption of constant light velocity that led him to special relativity. The enlarged covariance group leads to a non-commutative geometry based not on a manifold, but on a nonlocal space in which paths, rather than points, are the most primitive invariant entities. This yields a theory which unifies the gravitational and electroweak interactions. The theory contains no adjustable parameters, such as those that are chosen arbitrarily in the standard model.
On 3-regular 4-ordered graphs

A simple graph G is k-ordered (respectively, k-ordered hamiltonian), if for any sequence of k distinct vertices v"1,...,v"kof G there exists a cycle (respectively, hamiltonian cycle) in G containing these k vertices in the specified order. In 1997 Ng and Schultz introduced these concepts of cycle orderability and posed the question of the existence of 3-regular 4-ordered (hamiltonian) graphs other than K"4 and K"3","3. Ng and Schultz observed that a 3-regular 4-ordered graph on more than 4 vertices is triangle free. We prove that a 3-regular 4-ordered graph G on more than 6 vertices is square free,and we show that the smallest graph that is triangle and square free, namely the Petersen graph, is 4-ordered. Furthermore, we prove that the smallest graph after K"4 and K"3","3 that is 3-regular 4-ordered hamiltonianis the Heawood graph. Finally, we construct an infinite family of 3-regular 4-ordered graphs.
Observation of Mode Competition in an 11.4-GHz Magnicon Amplifier

This paper describes the observation of pulse shortening in an 11.4-GHz magnicon amplifier due to competition with a parasitic gyrotron mode. This effect was observed following the installation of a new electron beam collector. The parasitic mode occurred only at high operating powers, when the beam transverse momentum was high, and the growth of the parasitic mode caused the power in the output pulse to drop substantially. We analyze the competition between the gyrotron and magnicon modes in the output cavity using a time-dependent multimode gyrotron simulation code that has been specially modified to model competition between synchronous magnicon and nonsynchronous gyrotron interactions, and compare the results to experimental observations. We also analyze the effect due to the change in the collector.
Dynamics of microtubule instabilities

We investigate an idealized model of microtubule dynamics that involves: (i) attachment of guanosine triphosphate (GTP) at rate λ, (ii) conversion of GTP to guanosine diphosphate (GDP) at rate 1, and (iii) detachment of GDP at rate μ. As a function of these rates, a microtubule can grow steadily or its length can fluctuate wildly. For μ = 0, we find the exact tubule and GTP cap length distributions, and power-law length distributions of GTP and GDP islands. For μ = ∞, we argue that the time between catastrophes, where the microtubule shrinks to zero length, scales as eλ. We also discuss the nature of the phase boundary between a growing and shrinking microtubule.
Cascade multiterminal source coding

We investigate distributed source coding of two correlated sources X and Y where messages are passed to a decoder in a cascade fashion. The encoder of X sends a message at rate R1 to the encoder of Y. The encoder of Y then sends a message to the decoder at rate R 2 based both on Y and on the message it received about X. The decoder's task is to estimate a function of X and Y. For example, we consider the minimum mean squared-error distortion when encoding the sum of jointly Gaussian random variables under these constraints. We also characterize the rates needed to reconstruct a function of X and Y losslessly. Our general contribution toward understanding the limits of the cascade multiterminal source coding network is in the form of inner and outer bounds on the achievable rate region for satisfying a distortion constraint for an arbitrary distortion function d(x, y, z). The inner bound makes use of a balance between two encoding tactics—relaying the information about X and recompressing the information about X jointly with Y. In the Gaussian case, a threshold is discovered for identifying which of the two extreme strategies optimizes the inner bound. Relaying outperforms recompressing the sum at the relay for some rate pairs if the variance of X is greater than the variance of Y.
Genetic information, obesity, and labor market outcomes.

SUMMARY Economists have argued that obesity may lead to worse labor market outcomes, especially for women. Empirical methods to test this hypothesis have not thus far adequately controlled for the endogeneity of obesity. We use variation in genotype to predict variation in phenotype (obesity). Genetic information from specific genes linked to obesity in the biomedical literature provides strong exogenous variation in the body mass index and thus can be used as instrumental variables. These genes predict swings in weight of between 5 and 20 pounds for persons between five and six feet tall. We use additional genetic information to control for omitted variables correlated with both obesity and labor market outcomes. We analyzed data from the third wave of the Add Health data set, when respondents are in their mid-twenties. Results from our preferred models show no effect of lagged obesity on the probability of employment or on wages, for either men or women. This paper shows the potential of using genetic information in social sciences. Copyright r 2008 John Wiley & Sons, Ltd. Received 8 October 2007; Revised 23 April 2008; Accepted 29 April 2008
Snapshot-Based Balanced Truncation for Linear Time-Periodic Systems

We introduce an algorithm based on a method of snapshots for computing approximate balanced truncations for discrete-time, linear time-periodic systems. The algorithm is applicable to stable (including neutrally stable) systems with very high dimension, allowing either the output or the input to be very high dimensional, as well. This algorithm is illustrated with a numerical example.