cssi/SciSciGPT-SciSciNet huggingface dataset:
Dynamics and changing environments in highly optimized tolerance

Highly optimized tolerance (HOT) is a mechanism for power laws in complex systems based on the robust design of systems in uncertain environments. Once the system, the environment, and the optimization scheme have been specified, the HOT state is fixed and corresponds to the set of measure zero (typically a single point) in the configuration space which minimizes a cost function U. Here we explore the U-dependent structures in configuration space which are associated with departures from the optimal state. We introduce dynamics, quantified by an effective temperature T, such that $T=0$ corresponds to the original HOT state, while $\stackrel{\ensuremath{\rightarrow}}{T}\ensuremath{\infty}$ corresponds to completely random configurations. More generally, T defines the range in state space over which fluctuations are likely to be observed. In a fixed environment fluctuations always raise the average cost. However, in a time-dependent environment, mobile configurations can lower the average U because they adjust more efficiently to changes.
A chemoselective internal redox of allyl alcohols to saturated aldehydes or ketones

Abstract Cp(Ph 3 P) 2 RuCl efficiently isomerizes allyl alcohols to saturated aldehydes or ketones even in the presence of other olefins and saturated alcohols.
Mortality and extraintestinal cancers in patients with primary sclerosing cholangitis and inflammatory bowel disease.

Abstract Introduction Primary sclerosing cholangitis (PSC) and inflammatory bowel disease (IBD) frequently co-occur. PSC is associated with increased risk for colorectal cancer (CRC). However, whether PSC is associated with increased risk of extraintestinal cancers or affects mortality in an IBD cohort has not been examined previously. Methods In a multi-institutional IBD cohort of IBD, we established a diagnosis of PSC using a novel algorithm incorporating narrative and codified data with high positive and negative predictive value. Our primary outcome was occurrence of extraintestinal and digestive tract cancers. Mortality was determined through monthly linkage to the social security master death index. Results In our cohort of 5506 patients with CD and 5522 patients with UC, a diagnosis of PSC was established in 224 patients (2%). Patients with IBD–PSC were younger and more likely to be male compared to IBD patients without PSC; three-quarters had UC. IBD–PSC patients had significantly increased overall risk of cancers compared to patients without PSC (OR 4.36, 95% CI 2.99–6.37). Analysis of specific cancer types revealed that a statistically significant excess risk for digestive tract cancer (OR 10.40, 95% CI 6.86–15.76), pancreatic cancer (OR 11.22, 95% CI 4.11–30.62), colorectal cancer (OR 5.00, 95% CI 2.80–8.95), and cholangiocarcinoma (OR 55.31, 95% CI 22.20–137.80) but not for other solid organ or hematologic malignancies. Conclusions PSC is associated with increased risk of colorectal and pancreatobiliary cancer but not with excess risk of other solid organ cancers.
Rapid evaluation of synthetic and molecular complexity for in silico chemistry.

Methods that rapidly evaluate molecular complexity and synthetic feasibility are becoming increasingly important for in silico chemistry. We propose a new metric based on relative atomic electronegativities and bond parameters that evaluate both synthetic and molecular complexity (SMCM) starting from chemical structures. Against molecular weight, SMCM has the lowest fraction of adjusted variance (R2=0.535) on a series of 261 048 diverse compounds, when compared to the complexity metric of Baron and Chanon (R2=0.777; J. Chem. Inf. Comput. Sci. 2001, 41, 269−272) and Rucker (R2=0.895 for log complexity values; J. Chem. Inf. Comput. Sci. 2004, 44, 378−386), respectively. These metrics are in general agreement when the metabolic synthesis of cholesterol from S-3-hydroxy-3-methyl-glutaryl coenzyme A is monitored, indicating that SMCM can be useful in discerning increases in complexity. Because the presence of substructure patterns can be directly incorporated into this scheme, SMCM is relatively straightforwar...
Soil effects on thermal signatures of buried nonmetallic landmines

Thermal sensors hold much promise for the detection of non-metallic landmines. However, the prediction of their thermal signatures depends on a large number of factors. In this paper, an analytical solution for temperature propagation through homogeneous and layered soils is presented to predict surface temperatures as a function of soil heat flux amplitude, soil texture, soil water content, and thermal properties and burial depth of the landmine. Comparison with the numerical model HYDRUS-2D shows that the relatively simple analytical solution proposed here is reasonably accurate. The results show that an increase in soil water content has a significant effect on the thermal signature, as well as on the phase shift of the maximum temperature difference. Different soil textures have relatively little effect on the temperature at the surface. The thermal properties of the mine itself can play a significant role. It is shown that for most soils 10 cm is the maximum burial depth to produce a significant thermal signature at the surface.
Silicon, germanium, tin and lead analogues of acetylenes

Recent experimental results which have described the characterization of the first, stable heavier group 14 element analogues of acetylenes are outlined. It is shown that the use of large terphenyl substituents allows the isolation of transition metal-heavier group 14 element complexes that can achieve essential triple bonding by a three-fold orbital interaction between the transition metal and group 14 moiety. On the other hand the alkyne analogues RMMR (R = Ge, Sn or Pb) display increasing distortions from linearity to trans-bent geometry due to the accumulation of non-bonding electron density at the group 14 element. The non-bonding electron density comes at the expense of electron density in the bonding region between the group 14 elements. Accordingly the bond orders are decreased to values that are near double for the germanium and tin derivatives and single for the lead compound.
Semantics In Digital Photos: A Contenxtual Analysis

Interpreting the semantics of an image is a hard problem. However, for storing and indexing large multimedia collections, it is essential to build systems that can automatically extract semantics from images. In this research we show how we can fuse content and context to extract semantics from digital photographs. Our experiments show that if we can properly model context associated with media, we can interpret semantics using only a part of high dimensional content data.
Bagging multiple comparisons from microarray data

Bagging and subagging procedures are put forth with thepurpose of improving the discovery power in the context of large-scale simultaneous hypothesis testing. Bagging and subagging significantly improvediscovery power at the cost of a small increase in false discoveryrate with 'maximum contrast' subagging having an edge over bagging,i.e., yielding similar power but significantly smaller false discovery rates.The proposed procedures are implemented in a situation involving a wellknown dataset on gene expressions related to prostate cancer.
All-optical switching at ultra-low light levels

We report an experimental demonstration of all-optical switching with the signal and control light pulses containing about 20 photons each, corresponding to a control energy density of ~10-5 photons per atomic cross section lambda2 /(2 pi).
Making space for crime: A spatial analysis of criminal competition ☆

Abstract This paper utilizes a spatial competition model to analyze criminal activity. Criminals are heterogeneous in their cost of providing illegal goods and compete by choosing a location and a price for the distribution of the illegal goods to clients. The locational choice of criminals and law enforcement technology are permitted to interact and the spatial equilibrium of criminals is determined. A particularly striking finding is that an increase in law enforcement effort can increase the market share of criminals by forcing low productivity criminals out of the market, thereby allowing fewer criminals to serve the inelastic demands of the illegal goods market.
Pilot-symbol-assisted communications with noncausal and causal Wiener filters

In this paper, pilot-assisted transmission over time-selective flat fading channels is studied. It is assumed that noncausal and causal Wiener filters are employed at the receiver to perform channel estimation with the aid of training symbols sent periodically by the transmitter. For both filters, the variances of estimate errors are obtained from the Doppler power spectrum of the channel. Subsequently, achievable rate expressions are provided. The training period, and data and training power allocations are jointly optimized by maximizing the achievable rate expressions. Numerical results are obtained by modeling the fading as a Gauss-Markov process. The achievable rates of causal and noncausal filtering approaches are compared. For the particular ranges of parameters considered in the paper, the performance loss incurred by using a causal filter as opposed to a noncausal filter is shown to be small. The impact of aliasing that occurs in the undersampled version of the channel Doppler spectrum due to fast fading is analyzed. Finally, energy-per-bit requirements are investigated in the presence of noncausal and causal Wiener filters.
The Generalization Ability of Online Algorithms for Dependent Data

We study the generalization performance of online learning algorithms trained on samples coming from a dependent source of data. We show that the generalization error of any stable online algorithm concentrates around its regret-an easily computable statistic of the online performance of the algorithm-when the underlying ergodic process is β- or φ -mixing. We show high-probability error bounds assuming the loss function is convex, and we also establish sharp convergence rates and deviation bounds for strongly convex losses and several linear prediction problems such as linear and logistic regression, least-squares SVM, and boosting on dependent data. In addition, our results have straightforward applications to stochastic optimization with dependent data, and our analysis requires only martingale convergence arguments; we need not rely on more powerful statistical tools such as empirical process theory.
Finite-dimensional adaptive observers applied to distributed parameter systems

The application of finite-dimensional adaptive observers to distributed parameter systems is addressed. Ultimate boundedness of the parameter and state errors are proved in the case of residuals which have finite energy over a finite time interval, provided the plant input is definitely exciting. In the absence of definite excitation, an error growth rate of proportional to t/sup 1/2/ is proved. The results are obtained without assuming plant stability or input boundedness. >
STRUCTURAL STABILITY OF THE GENERALIZED TAYLOR RULE

This paper analyzes the dynamical properties of monetary models with regime switching. We start with the analysis of the evolution of inflation when policy is guided by a simple monetary rule where coefficients switch with the policy regime. We rule out the possibility of a Hopf bifurcation and demonstrate the existence of a period doubling bifurcation. As a result, a small change in the parameters (e.g., a more active policy response) can lead to a drastic change in the path of inflation. We demonstrate that while the New Keynesian model with a current-looking Taylor rule is not prone to bifurcations, a hybrid rule exhibits the same pattern of period doubling bifurcations as the basic setup.
The Economic Origins of Democracy Reconsidered

The effects of inequality and financial globalization on democratization are central issues in political science. The relationships among economic inequality, capital mobility, and democracy differ in the late twentieth century for financially integrated autocracies vs. closed autocracies. Financial integration enables native elites to create diversified international asset portfolios. Asset diversification decreases both elite stakes in and collective action capacity for opposing democracy. Financial integration also changes the character of capital assets—including land—by altering the uses of capital assets and the nationality of owners. It follows that financially integrated autocracies, especially those with high levels of inequality, are more likely to democratize than unequal financially closed autocracies. We test our argument for a panel of countries in the post–World War II period. We find a quadratic hump relationship between inequality and democracy for financially closed autocracies, but an upward sloping relationship between inequality and democratization for financially integrated autocracies.
On the Structure of Liquid Hydrogen Fluoride

The liquid state is the most complex phase of matter. Densities of liquids are comparable to densities of the solids, implying that the forces between particles in the liquid are of the same magnitude as those forces present in the solid. However, there is no simplification due to the presence of a lattice and no satisfactory analytic theory of the liquid state exists. However, despite this complexity, the liquid state is an outstandingly important chemical milieu in which many reactions take place. Strongly associated fluids are particularly complex and the structure and properties of these fluids provide an exacting and stringent test of theory. Here, we report the first investigation of the structure of hydrogen fluoride at the level of the distributions of pairwise interatomic distances, the partial pair correlation functions. Liquid HFis an important chemical and it is widely used in the petrochemical industry, as a catalyst for hydrocarbon management, and in the glass and ceramics industries. [1, 2] Academically, its superior properties as a solvent have found application in both organic and inorganic chemistry, and the superacidic properties have been exploited in both disciplines, in the study of reactive intermediates and reaction mechanisms [3, 4] That these highly desirable properties are not more widely applied is mainly due to the exceedingly toxic and corrosive nature of the material, [5] which is severe when anhydrous and only somewhat lessened in solution. Indeed, given the properties of liquid HF, it has been stated that the calculation of its properties is to be preferred over measurement. [6] The true importance of this fluid does not solely rest with its industrial and academic applications; it is the simplest archetype for the strong hydrogen bond, and the molecular
Internal solitary waves induced by flow over a ridge: With applications to the northern South China Sea

[1] The generation of internal solitary waves by barotropic tides over a ridge is studied in a nonhydrostatic numerical model under idealized oceanographic settings. The experiments examine the effects of ridge width, barotropic tidal strength, and stratification on wave generation. The barotropic tidal flow produces internal wave beams emitting from the ridge top if the slope of the ridge exceeds a critical value equal to the slope of the wave beam. Reflection and refraction of a wave beam in an upper ocean waveguide associated with a strong shallow thermocline produce horizontally propagating internal tides. When the local Froude number over a ridge is not small, lee waves generated on the ridge convert enough energy from the barotropic tides to the internal tides to form tidal bores and solitary waves. Increasing stratification at ridge depths enhances the generation of internal waves, particularly at the diurnal periods. In the Luzon Strait, the slope of the wave beam decreases in spring and summer as stratification at the ridge depths increases, favoring the generation of internal tides. Without the presence of a strong shallow thermocline, internal solitary waves are not observed east of the Luzon Strait. In the northern South China Sea, internal solitary waves are likely observed from April to July when a strong shallow thermocline is present. A deep mixed layer in winter suppresses the production of internal solitary waves.
America’s Deficit, the World’s Problem

The U.S. deficit in the current account, now running at an annual rate of over US$700 billion, has reached levels (as a percentage of GDP) not seen since the first decades of the 19th century. The deficit is soaking up roughly three-quarters of the world’s available external surpluses. If the deficit continues at this pace, the U.S. could ultimately converge to an external debt/GDP ratio around one. Several analyses suggest that a rapid adjustment of the deficit toward balance would require a very sharp real depreciation of the U.S. dollar. This paper reviews the limitations of some optimistic arguments that predict instead a “soft landing” for the dollar. I focus in particular on the view that greater financial globalization allows the United States easily to run much bigger deficits for much longer periods. Some simple calculations based on real interest rate differentials suggest that markets could be underestimating the extent of necessary dollar depreciation.
h-Vectors of matroids and logarithmic concavity

Abstract Let M be a matroid on E, representable over a field of characteristic zero. We show that h-vectors of the following simplicial complexes are log-concave: 1. The matroid complex of independent subsets of E. 2. The broken circuit complex of M relative to an ordering of E. The first implies a conjecture of Colbourn on the reliability polynomial of a graph, and the second implies a conjecture of Hoggar on the chromatic polynomial of a graph. The proof is based on the geometric formula for the characteristic polynomial of Denham, Garrousian, and Schulze.
THE ALGEBRAS OF LARGE N MATRIX MECHANICS

Extending early work, we formulate the large N matrix mechanics of general bosonic, fermionic and supersymmetric matrix models, including Matrix theory: The Hamiltonian framework of large N matrix mechanics provides a natural setting in which to study the algebras of the large N limit, including (reduced) Lie algebras, (reduced) supersymmetry algebras and free algebras. We find in particular a broad array of new free algebras which we call symmetric Cuntz algebras, interacting symmetric Cuntz algebras, symmetric Bose/Fermi/Cuntz algebras and symmetric Cuntz superalgebras, and we discuss the role of these algebras in solving the large N theory. Most important, the interacting Cuntz algebras are associated to a set of new (hidden!) local quantities which are generically conserved only at large N. A number of other new large N phenomena are also observed, including the intrinsic nonlocality of the (reduced) trace class operators of the theory and a closely related large N field identification phenomenon which is associated to another set (this time nonlocal) of new conserved quantities at large N.
Searching for sustainable microfinance : a review of five Indonesian initiatives

Expanding the microfinance market can promote economic growth and reduce poverty in many countries. But expanding this market is advantageous only if the increased activity is sustainable. The author draws lessons from five Indonesian microfinance initiatives in rural areas and proposes ways for governments and donors to support the microfinance sector. Those programs demonstrate that microfinance initiatives can provide a valuable service to low-income people at a temporary, affordable cost to governments of donors. Incentives for customers and staff are key features of successful microfinance operations that enable them to operate with low subsidies or on a self-sustaining basis. Programs should also charge adequate real interest rates, aggressively pursue repayment, and achieve a significant volume of business. To accelerate progress toward self-sustainability, programs can track the subsidies they receive, and their supporters can impose hard budget constraints and declining subvention support. Government-owned microfinance initiatives are vulnerable to political pressures that undermine their commitment to sound banking practices. Granting these institutions autonomous status, imposing hard budget constraints, and privatizing them when they are financially sustainable, can reduce their susceptibility to political influences. Alternatively, governments and donors could support the sector through temporary subsidies to private sector initiatives to help them defray start-up costs. Supervision can be improved if a country's microfinance industry, assisted by its central bank, establishes industrywide standards. Microfinance institutions could contract for supervision services from commercial banks. The central bank could monitor supervisors to ensure that they exercise due diligence. This study finds that institutions can efficiently reach clients in remote areas through subdistrict-based units and field staff. They need not rely on group lending techniques, savings requirements, or intermediary organizations between banks and borrowers to boost efficiency. Initiatives can serve female borrowers without targeted marketing if loan products meet women's needs and are accessible to them. Governments could increase the usefulness of microfinance to agriculture by encouraging state-owned microfinance institutions to develop and pilot-test loan products that meet smallholders' needs.
Heteroatoms moving protons: Synthetic and mechanistic studies of bifunctional organometallic catalysis

Improved organometallic catalysts resulting from including ligands capable of pro- ton transfer or hydrogen bonding are described. Pyridyl- and imidazolylphosphines acceler- ate anti-Markovnikov alkyne hydration and alkene isomerization and deuteration by factors of 1000 to more than 10 000. Evidence for proton transfer and hydrogen bonding in catalytic intermediates comes from computational, mechanistic, and structural studies, where 15 N NMR data are particularly revealing.
Quantifying causal mechanisms to determine how protected areas affect poverty through changes in ecosystem services and infrastructure

To develop effective environmental policies, we must understand the mechanisms through which the policies affect social and environmental outcomes. Unfortunately, empirical evidence about these mechanisms is limited, and little guidance for quantifying them exists. We develop an approach to quantifying the mechanisms through which protected areas affect poverty. We focus on three mechanisms: changes in tourism and recreational services; changes in infrastructure in the form of road networks, health clinics, and schools; and changes in regulating and provisioning ecosystem services and foregone production activities that arise from land-use restrictions. The contributions of ecotourism and other ecosystem services to poverty alleviation in the context of a real environmental program have not yet been empirically estimated. Nearly two-thirds of the poverty reduction associated with the establishment of Costa Rican protected areas is causally attributable to opportunities afforded by tourism. Although protected areas reduced deforestation and increased regrowth, these land cover changes neither reduced nor exacerbated poverty, on average. Protected areas did not, on average, affect our measures of infrastructure and thus did not contribute to poverty reduction through this mechanism. We attribute the remaining poverty reduction to unobserved dimensions of our mechanisms or to other mechanisms. Our study empirically estimates previously unidentified contributions of ecotourism and other ecosystem services to poverty alleviation in the context of a real environmental program. We demonstrate that, with existing data and appropriate empirical methods, conservation scientists and policymakers can begin to elucidate the mechanisms through which ecosystem conservation programs affect human welfare.
Computer and telecommunications equipment room cooling: a review of literature

Due to technology compaction, the information technology (IT) industry has seen a large increase in power density and heat dissipation within the footprint of computer and telecommunications hardware. The heat dissipated in these systems is exhausted to the room and the room has to be maintained at acceptable temperatures for reliable operation of the equipment. Cooling computer and telecommunications equipment rooms is becoming a major challenge. This paper reviews the literature dealing with various aspects of cooling computer and telecommunications equipment rooms. Included are papers on experimental work analyzing cooling schemes, numerical modeling, energy saving schemes, natural convection room cooling, forced convection room cooling, cooling raised floor versus nonraised floor type installations, and other related areas.
Output control using feedforward and cascade controllers

Open-loop solution to the output control problem in SISO systems by means of feedforward and cascade controllers is investigated in this paper. A simple characterization of feedforward controllers which achieve steady-state disturbance rejection is given in a transfer-function setting. Cascade controllers which cause steady-state command tracking are also characterized. Furthermore, disturbance decoupling and command matching controllers are identified. Conditions for existence of feedforward and cascade controllers are also given. For unstable systems, it is shown that a stabilizing feedback controller can be employed without affecting the feedforward and cascade controllers used for output control; hence, the three controllers can be designed independently. Finally, output control by a combination of feedforward and feedback is discussed briefly.
Viability of clathrin heavy-chain-deficient Saccharomyces cerevisiae is compromised by mutations at numerous loci: implications for the suppression hypothesis.

Abstract The gene encoding clathrin heavy chain in Saccharomyces cerevisiae (CHC1) is not essential for growth in most laboratory strains tested. However, in certain genetic backgrounds, a deletion of CHC1 (chc1) results in cell death. Lethality in these chc1 strains is determined by a locus designated SCD1 (suppressor of clathrin deficiency) which is unlinked to CHC1 (S. K. Lemmon and E. W. Jones, Science 238:504-509, 1987). The lethal allele of SCD1 has no effect on cell growth when the wild-type version of CHC1 is present. This result led to the proposal that most yeast strains are viable in the absence of clathrin heavy chain because they possess the SCD1 suppressor. Discovery of another yeast strain that cannot grow without clathrin heavy chain has allowed us to perform a genetic test of the suppressor hypothesis. Genetic crosses show that clathrin-deficient lethality in the latter strain is conferred by a single genetic locus (termed CDL1, for clathrin-deficient lethality). By constructing strains in which CHC1 expression is regulated by the GAL10 promoter, we demonstrate that the lethal alleles of SCD1 and CDL1 are recessive. In both cases, very low expression of CHC1 can allow cells to escape from lethality. Genetic complementation and segregation analyses indicate that CDL1 and SCD1 are distinct genes. The lethal CDL1 allele does not cause a defect in the secretory pathway of either wild-type or clathrin heavy-chain-deficient yeast. A systematic screen to identify mutants unable to grow in the absence of clathrin heavy chain uncovered numerous genes similar to SCD1 and CDL1. These findings argue against the idea that viability of chc1 cells is due to genetic suppression, since this hypothesis would require the existence of a large number of unlinked genes, all of which are required for suppression. Instead, lethality appears to be a common, nonspecific occurrence when a second-site mutation arises in a strain whose cell growth is already severely compromised by the lack of clathrin heavy chain.
On the Penetration of Daylight into the Sea

During descents into the sea to depths of over 1,400 feet Beebe observed that the color of the water during the midday hours of a sunny day was a pure blue and measured the candle-power of the illumination at various depths down to 800 feet (Beebe, Bull. New York Zoological Society, v. 33, 201, 1930). At 800 feet the spectrum was a narrow band centering about wave-length 520μμ The absorption of light in the visible and ultraviolet portions of the spectrum by samples of pure sea-water taken from the Gulf Stream, the Atlantic and Pacific oceans, and the Caribbean Sea far from land have been measured in the Laboratory (Hulburt, J. Opt. Soc. Amer., v. 13, 553, 1926, and v. 17, 15, 1928). Using the Laboratory absorption-coefficients and the Raman-Einstein-Smoluchowski theory of the scattering of light in liquids, it is found that the spectrum of the daylight at 800 feet in the sea has a maximum brightness at about 500μμ. This agrees with Beebe's result probably within the error of the observations.
Taming symplectic forms and the Calabi-Yau equation

We study the Calabi-Yau equation on symplectic manifolds. We show that Donaldson's conjecture on estimates for this equation in terms of a taming symplectic form can be reduced to an integral estimate of a scalar potential function. Under a positive curvature condition, we show that the conjecture holds.
The Nonparanormal: Semiparametric Estimation of High Dimensional Undirected Graphs

Recent methods for estimating sparse undirected graphs for real-valued data in high dimensional problems rely heavily on the assumption of normality. We show how to use a semiparametric Gaussian copula---or "nonparanormal"---for high dimensional inference. Just as additive models extend linear models by replacing linear functions with a set of one-dimensional smooth functions, the nonparanormal extends the normal by transforming the variables by smooth functions. We derive a method for estimating the nonparanormal, study the method's theoretical properties, and show that it works well in many examples.
Faint-Source Counts from Off-Source Fluctuation Analysis on Chandra Observations of the Hubble Deep Field-North

We report the results of fluctuation analysis of the off-source field from the 1 million second Chandra observation of the Hubble Deep Field-North (HDF-N). The distribution of the counts in cells has been compared with the expectations from the log N-log S model to constrain the behavior of the source number density down to a factor of several lower than the source detection limit. Our results show that the number counts in the soft band (0.5-2 keV) continue to grow down to SX ~ 7 × 10-18 ergs s-1 cm-2, possibly suggesting the emergence of a new population, and agree well with a prediction of star-forming galaxies by Ptak et al. The fluctuation analysis can loosely constrain the source counts fainter than the detection limit, and we found an upper limit of 10,000 sources deg-2 at SX ~ 2 × 10-16 ergs s-1 cm-2 in the hard (2-10 keV) band.
SSRL beam position monitor detection electronics

As part of a program to improve its orbit stability, SSRL is redesigning its detection electronics for its beam position monitors (BPMs). The electronics must provide highly reproducible positional information at the low bandwidth required of an orbit feedback system. With available commercial technology, it is now possible to obtain highly resolved turn by turn information so that this electronic module can also be used to measure beam dynamics. The design criteria for this prototype system and performance of the analog section of the processor is discussed.
Straightforward computation of spatial equilibria of geometrically exact Cosserat rods

In this paper, we present a well posed "force" based formulation for nonlinearly elastic Cosserat rods with general boundary conditions enabling straightforward, efficient computation of spatial eq...
Parallelism in Manipulator Dynamics

This paper addresses the problem of efficiently computing the motor torques required to drive a manipulator arm in free motion, given the desired trajectory—that is the inverse dynamics problem. It analyzes the high degree of parallelism inherent in the computations and presents two "mathemati cally exact "formulations especially suited to high-speed, highly parallel implementations using VLSI devices. The first method presented is a parallel version of the recent linear Newton-Euler recursive algorithm. The time cost is linear in the number of joints, but the real-time coefficients are re duced by almost two orders of magnitude. The second formu lation reports a new parallel algorithm that shows that it is possible to improve on the linear time dependency. The real time required to perform the calculations increases only as the [log2] of the number of joints. Either formulation is sus ceptible to a systolic pipelined architecture in which complete sets of joint torques emerge at successive intervals of f...
Visual design steering for optimization solution improvement

The paradigm of Visual Design Steering is applied to formal optimal design solution algorithms to improve efficiency, accuracy, and reliability. A formal procedure is presented that guides a designer to utilize the method of Graph Morphing with a formal optimization process. The procedure starts with reduction of the problem for visualization purposes through a ranking and reduction of design variables and constraints. The procedure then outlines how the reduced problem may be visualized using the method of Graph Morphing. Following this procedure an initial point is selected which can produce an improved final solution point in less time than if the solution were started from a random initial point. Several examples are presented which demonstrate this capability.
Computer simulations of disruption

The Isis and Wave plasma simulation codes were used to examine the disruption of e/sup +/e/sup -/ beams. Qualitative agreement was found with the results of P. Chen and K. Yokoya (1988) in all three of the disruption regimes (weak focusing, transition, and confined). Quantitatively, the present results for H/sub D/ at A=0 are higher than those of R. Hollebeek (1981) and W.M. Fawley, and E.P. Lee (1987) and higher than the highest curves of Chen and Yokoya (A=0.05). However, H/sub D/ remained finite at A=0 in simulation, contrary to the prediction of Chen and Yokoya. A possible explanation for the quantitative differences between the present simulations and those of others is the low level of approximation in the present codes. >
THE GEODESIC RULE AND THE SPECTRUM OF THE VACUUM

We analyze the consequences of a recent argument justifying the validity of the "geodesic rule" which can be used to determine the density of global topological defects. We derive a formula that provides a rough estimate of the number of string-like defects formed in a phase transition. We apply this formula to vacua which are spheres. We provide some reasons for the deviation of our predictions from the corresponding accepted values.
Chemical mediation of interactions among marine organisms

Covering: the literature up to 2003 This review covers the recent marine chemical ecology literature for macroalgae, sponges, octocorals and other benthic invertebrates; 332 references are cited.
Robust Parafoil Terminal Guidance Using Massively Parallel Processing

Terminal guidance of autonomous parafoils is a difficult problem in which wind uncertainty and system underactuation are major challenges. Existing strategies almost exclusively use impact error as the criterion for optimality. Practical airdrop systems, however, must also include other criteria that may be even more important than impact error for some missions, such as ground speed at impact or constraints imposed by drop zones with restrictions on flight patterns. Furthermore, existing guidance schemes determine terminal trajectories using deterministic wind information and may result in a solution that works in ideal wind but may be sensitive to variations. The work described here develops a guidance strategy that uses massively parallel Monte Carlo simulation performed on a graphics processing unit to rank candidate trajectories in terms of robustness to wind uncertainty. The result is robust guidance, as opposed to optimal guidance. Through simulation results, the proposed path planning scheme prove...
Quantum cluster algebras

Cluster algebras form an axiomatically defined class of commutative rings designed to serve as an algebraic framework for the theory of total positivity and canonical bases in semisimple groups and their quantum analogs. In this paper we introduce and study quantum deformations of cluster algebras.
N=1 heterotic / F theory duality

We review aspects of N=1 duality between the heterotic string and F-theory. After a description of string duality intended for the non-specialist the framework and the constraints for heterotic/F-theory compactifications are presented. The computations of the necessary Calabi-Yau manifold and vector bundle data, involving characteristic classes and bundle moduli, are given in detail. The matching of the spectrum of chiral multiplets and of the number of heterotic five-branes respectively F-theory three-branes, needed for anomaly cancellation in four-dimensional vacua, is pointed out. Several examples of four-dimensional dual pairs are constructed where on both sides the geometry of the involved manifolds relies on del Pezzo surfaces.
Evaluation of slot allocation strategies for TDMA protocols in packet radio networks

Time-division multiple-access (TDMA) protocols provide packet radio networks with useful features that facilitate efficient communications. Many different algorithms have been proposed to maximize the reuse of the bandwidth and simultaneously minimize the TDMA frame length. The resulting slot assignments of these algorithms can be grouped into two general strategies for assigning transmissions rights to nodes: node and link allocation. The performance of each allocation strategy is evaluated using a detailed simulation. The results indicate that in all cases, for both single-destination packets and broadcast packets, node allocation offers better delay performance than link allocations. >
Chandra HETG Spectra of SN 1987A at 20 Years

We have undertaken deep, high-resolution observations of SN 1987A at ≈20 years after its explosion with the Chandra HETG and LETG spectrometers. Here we present the HETG X-ray spectra of SN 1987A having unprecedented spectral resolution and signal-to-noise ratios in the 6–20 bandpass, which includes the H-like u A and He-like lines of Si, Mg, and Ne, as well as O viii lines and bright Fe xvii lines. In joint analysis with LETG data, we find that there has been a significant decrease from 2004 to 2007 in the average temperature of the highest temperature component of the shocked-plasma emission. Model fitting of the profiles of individual HETG lines yields bulk kinematic velocities of the higher-Z ions, Mg and Si, that are significantly lower than those inferred from the LETG 2004 observations. Subject headings: ISM: individual (SN 1987A) — radiation mechanisms: thermal — supernova remnants — techniques: spectroscopic — X-rays: ISM
Financial safety nets and incentive structures in Latin America

The literature on safety nets has become technically more precise by drawing on advances in contract theory and optimal governance structure. This paper begins with a treatment of some aspects of the theory. The author's approach draws more on institutional economics, and more precisely on the approach taken by Kindleberger (1978), in the sense that he believes the design of good financial safety nets for Latin America depends upon an understanding of the way that formal ex-ante safety nets have broken down during times of crisis over the past one hundred years. In this paper then author explores issues surrounding safety nets for financial systems in small open economies like those in Latin America. The starting point in Section 2 is the idea that asymmetric information will generally restrict the scope for lending to potential borrowers. Section 3 shows that government regulation of financial intermediaries can frequently lower the cost of lending. Section 4 discusses the creation of central banks in Latin America in the 1920s as an innovation to promote financial deepening. Section 5 shows that the extension of the safety net to depositors is a relatively new and untested development. Section 6 concludes with a discussion of the design of safety nets that takes into account the principles developed in the paper.
N-alkylation of lactams with secondary heterobenzylic bromides

We herein report a general N-alkylation reaction of lactams with secondary heterobenzylic bromides. This methodology features mild reaction condition, moderate to high product isolation yield, and broad substrate scope. Good chemical and structural tolerance has also been demonstrated by both the secondary heterobenzylic bromides and lactam substrates.
On the feasibility of using wireless ethernet for indoor localization

IEEE 802.11b wireless Ethernet is becoming the standard for indoor wireless communication. This paper proposes the use of measured signal strength of Ethernet packets as a sensor for a localization system. We demonstrate that off-the-shelf hardware can accurately be used for location sensing and real-time tracking by applying a Bayesian localization framework.
The half-integral weight eigencurve

In this paper we define Banach spaces of overconvergent half-integral weight p-adic modular forms and Banach modules of families of overconvergent halfintegral weight p-adic modular forms over admissible open subsets of weight space. Both spaces are equipped with a continuous Hecke action for which Up2 is moreover compact. The modules of families of forms are used to construct an eigencurve parameterizing all finite-slope systems of eigenvalues of Hecke operators acting on these spaces. We also prove an analog of Coleman’s theorem stating that overconvergent eigenforms of suitably low slope are classical.
Maximum Induced Forests in Graphs of Bounded Treewidth

Given a nonnegative integer $d$ and a graph $G$, let $f_d(G)$ be the maximum order of an induced forest in $G$ having maximum degree at most $d$. We seek lower bounds for $f_d(G)$ based on the order and treewidth of $G$. We show that, for all $k,d\ge 2$ and $n\ge 1$, if $G$ is a graph with order $n$ and treewidth at most $k$, then $f_d(G)\ge\lceil{(2dn+2)/(kd+d+1)}\rceil$, unless $G\in\{K_{1,1,3},K_{2,3}\}$ and $k=d=2$. We give examples that show that this bound is tight to within $1$. We conjecture a bound for $d=1$: $f_1(G) \ge\lceil{2n/(k+2)}\rceil$, which would also be tight to within $1$, and we prove it for $k\le 3$. For $k\ge 4$ the conjecture remains open, and we prove a weaker bound: $f_1(G)\ge (2n+2)/(2k+3)$. We also examine the cases $d=0$ and $k=0,1$. Lastly, we consider open problems relating to $f_d$ for graphs on a given surface, rather than graphs of bounded treewidth.
Stable Cyclic Carbenes and Related Species beyond Diaminocarbenes

The success of homogeneous catalysis can be attributed largely to the development of a diverse range of ligand frameworks that have been used to tune the behavior of various systems. Spectacular results in this area have been achieved using cyclic diaminocarbenes (NHCs) as a result of their strong σ-donor properties. Although it is possible to cursorily tune the structure of NHCs, any diversity is still far from matching their phosphorus-based counterparts, which is one of the great strengths of the latter. A variety of stable acyclic carbenes are known, but they are either reluctant to bind metals or they give rise to fragile metal complexes. During the last five years, new types of stable cyclic carbenes, as well as related carbon-based ligands (which are not NHCs), and which feature even stronger σ-donor properties have been developed. Their synthesis and characterization as well as the stability, electronic properties, coordination behavior, and catalytic activity of the ensuing complexes are discussed, and comparisons with their NHC cousins are made.
A 900-MHz 2.5-mA CMOS frequency synthesizer with an automatic SC tuning loop

A 900-MHz phase-locked loop frequency synthesizer implemented in a 0.6-/spl mu/m CMOS technology is developed for the wireless integrated network sensors applications. It incorporates an automatic switched-capacitor (SC) discrete-tuning loop to extend the overall frequency tuning range to 20%, while the VCO gain (K/sub VCO/) resulting from the CMOS varactor continuous-tuning is kept low at only 20 MHz/V in order to improve the reference spurs and noise performance. This frequency synthesizer achieves a phase noise of -102 dBc/Hz at 100 kHz offset frequency and reference spurs below -55 dBc. The synthesizer, including an on-chip VCO, dissipates only 2.5 mA from a 3-V supply.
The Isotropic Semicircle Law and Deformation of Wigner Matrices

We analyze the spectrum of additive finite-rank deformations of N × N Wigner matrices H. The spectrum of the deformed matrix undergoes a transition, associated with the creation or annihilation of an outlier, when an eigenvalue di of the deformation crosses a critical value ± 1. This transition happens on the scale . We allow the eigenvalues di of the deformation to depend on N under the condition . We make no assumptions on the eigenvectors of the deformation. In the limit N ∞, we identify the law of the outliers and prove that the nonoutliers close to the spectral edge have a universal distribution coinciding with that of the extremal eigenvalues of a Gaussian matrix ensemble. A key ingredient in our proof is the isotropic local semicircle law, which establishes optimal high-probability bounds on where m(z) is the Stieltjes transform of Wigner's semicircle law and v, w are arbitrary deterministic vectors.© 2013 Wiley Periodicals, Inc.
Reflections on the Literature

AbstractThis paper considers two areas of current research related to environmental economics: 1. the use of quasi-experimental or “experimentalist” methods to evaluate the effects of environmental...
Sensitivity analysis for thermophysical property measurements using the periodic method

The frequency domain provides an interesting alternative platform for measuring thermophysical properties. The resulting measurement technique produces reasonably accurate thermophysical data from imprecise surface information. Having a periodic heat flux input at one surface, the thermal diffusivity is obtainable if temperature produces a measurable periodic effect at another location. The analysis shows that only the phase shift is necessary to produce needed information while the boundary conditions can affect the experimental results. This method was tested near room temperature using two different materials: Delrin and 304 stainless steel. The experiments yield accurate thermal diffusivity data for both materials but the data for Delrin exhibit smaller errors. Before performing the experiments, a sensitivity analysis was carried out to determine the best range of frequencies for an experimental investigation.
On the formation of singularities of solutions of nonlinear differential systems in antistokes directions

We determine the position and the type of spontaneous singularities of solutions of generic analytic nonlinear differential systems in the complex plane, arising along antistokes directions towards irregular singular points of the system. Placing the singularity of the system at infinity we look at equations of the form $\mathbf{y}'=\mathbf{f}(x^{-1},\mathbf{y})$ with $\mathbf{f}$ analytic in a neighborhood of $(0,\mathbf{0})$, with genericity assumptions; $x=\infty$ is then a rank one singular point. We analyze the singularities of those solutions $\mathbf{y}(x)$ which tend to zero for $x\to \infty$ in some sectorial region, on the edges of the maximal region (also described) with this property. After standard normalization of the differential system, it is shown that singularities occuring in antistokes directions are grouped in nearly periodical arrays of similar singularities as $x\to\infty$, the location of the array depending on the solution while the (near-) period and type of singularity are determined by the form of the differential system.