cssi/SciSciGPT-SciSciNet huggingface dataset:
HIGH-FREQUENCY GRAVITATIONAL WAVES FROM SUPERMASSIVE BLACK HOLES: PROSPECTS FOR LIGO-VIRGO DETECTIONS

It is commonly assumed that ground-based gravitational wave (GW) instruments will not be sensitive to supermassive black holes (SMBHs) because the characteristic GW frequencies are far below the ~10-1000 Hz sensitivity bands of terrestrial detectors. Here, however, we explore the possibility of SMBH GWs to leak to higher frequencies. In particular, if the high-frequency spectral tail asymptotes to , where α ≤ 2, then the spectral amplitude is a constant or increasing function of the mass M at a fixed frequency f c 3/GM. This will happen if the time-domain waveform or its derivative exhibits a discontinuity. Ground-based instruments could search for these universal spectral tails to detect or rule out such features irrespective of their origin. We identify the following processes which may generate high-frequency signals: (1) gravitational bremsstrahlung of ultrarelativistic objects in the vicinity of an SMBH, (2) ringdown modes excited by an external process that has a high-frequency component or terminates abruptly, and (3) gravitational lensing echoes and diffraction. We estimate the order of magnitude of the detection signal-to-noise ratio for each mechanism (1, 2, and 3) as a function of the waveform parameters. In particular for (3), SMBHs produce GW echoes of inspiraling stellar mass binaries in galactic nuclei with a delay of a few minutes to hours. The lensed primary signal and GW echo are both amplified if the binary is within a ~10 deg (r/100M)–1/2 cone behind the SMBH relative to the line of sight at a distance r from the SMBH. For the rest of the binaries near SMBHs, the amplitude of the GW echo is ~0.1(r/100M)–1 of the primary signal on average.
Economic transition and the distributions of income and wealth

Using a model of wealth distribution dynamics and occupational choice, the author investigates the distributional consequences of policies and developments associated with the transition from central planning to a market system. The model suggests that even an efficient privatization designed to be egalitarian may lead to increases in inequality (and possibly poverty), both during the transition and in the new steady state. Creating new markets in services that are also supplied by the public sector may also contribute to an increase in inequality. So can labor market reforms that lead to a decompression of the earnings structure and to greater flexibility in employment. The results underline the importance of retaining government provision of basic public goods and services, removing barriers that prevent the participation of the poor in the new private sector, and ensuring that suitable safety nets are in place.
Physics beyond the standard model

The author briefly summarizes the prospects for extending the understanding of physics beyond the standard model within the next five years. He interprets ``beyond the standard model'' to mean the physics of electroweak symmetry breaking, including the standard model Higgs boson. The nature of this TeV-scale new physics is perhaps the most crucial question facing high-energy physics, but one should recall (neutrino oscillations) that there is ample evidence for interesting physics in the flavour section too. In the next five years, before the LHC starts operations, the facilities available will be LEP2, HERA and the Fermilab Tevatron. He devotes a bit more time to the Tevatron as it is a new initiative for United Kingdom institutions. The Tevatron schedule now calls for data taking in Run II, using two upgraded detectors, to begin on March 1, 2001, with 2 fb{sup {minus}1} accumulated in the first two years. A nine-month shutdown will follow, to allow new silicon detector layers to be installed, and then running will resume with a goal of accumulating 15 fb{sup {minus}1} (or more) by 2006.
Boundary counterterms and the thermodynamics of 2-D black holes

We utilize a novel method to study the thermodynamics of two dimensional type 0A black holes with constant RR flux. Our approach is based on the Hamilton-Jacobi method of deriving boundary counterterms. We demonstrate this approach by recovering the standard results for a well understood example, Witten's black hole. Between this example and the 0A black hole we find universal expressions for the entropy and black hole mass, as well as the infra-red divergence of the partition function. As a non-trivial check of our results we verify the first law of thermodynamics for these systems. Our results for the mass disagree with the predictions of a proposed matrix model dual of the 0A black hole.
Provenance for database transformations

Database transformations (queries, views, mappings) take apart, filter, and recombine source data in order to populate warehouses, materialize views, and provide inputs to analysis tools. As they do so, applications often need to track the relationship between parts and pieces of the sources and parts and pieces of the transformations' output. This relationship is what we call database provenance.This talk presents an approach to database provenance that is based on two observations. First, provenance is a kind of annotation, and we can develop a general approach to annotation propagation that also covers other applications, for example to uncertainty and access control. In fact, provenance turns out to be the most general kind of such annotation, in a precise and practically useful sense. Second, the propagation of annotation through a broad class of transformations relies on just two operations: one when annotations are jointly used and one when they are used alternatively. This leads to annotations forming a specific algebraic structure, a commutative semiring.The semiring approach works for annotating tuples, field values and attributes in standard relations, in nested relations (complex values), and for annotating nodes in (unordered) XML. It works for transformations expressed in the positive fragment of relational algebra, nested relational calculus, unordered XQuery, as well as for Datalog, GLAV schema mappings, and tgd constraints. Specific semirings correspond to earlier approaches to provenance, while others correspond to forms of uncertainty, trust, cost, and access control.This is joint work with J. N. Foster, T. J. Green, Z. Ives, and G. Karvounarakis, done in part within the frameworks of the Orchestra and pPOD projects.
Base conversion mappings

Most computers utilize either binary, octal or hexadecimal representation for internal storage of numbers, whereas decimal format is desired for most input, output and for the representation of constants in a user language such as FORTRAN or ALGOL. The conversion of a normalized number in one base to a normalized number in another base is beset with difficulties because of the incompatibility of exact representations of a number when only a limited number of digits are available in each base.
Ten Nanometer Surface Intrusions in Room-Temperature Silicon

As gigascale integrated circuit devices approach nanometer dimensions, the bulk and surface structure of single crystal silicon is attracting finer scrutiny. In this context, recent searches for bulk defects 10 nm in size required that we consider more carefully some ubiquitous but weakly strained specimen preparation artifacts that for studies of larger bulk defects we had ignored. Transmission electron microscopy ~TEM! observations show that these imperfections, which form in variously oriented silicon surfaces after exposure to air, are strikingly similar after thinning with physically different methods. Moreover, the process of their formation can be slowed to laboratory time scales at room temperature if air exposure is sufficiently short. This allows in situ study of nucleation and growth, offering a view of dynamic processes in silicon which take place on laboratory time scales at room temperature, including the movement of self-interstitials and surface diffusion barrier formation. Both of these are subjects of widespread fundamental and applied interest. 1-4
On spectral gap rigidity and Connes invariant $\chi(M)$

We calculate Connes' invariant for certain II factors that can be obtained as inductive limits of subfactors with spectral gap. Then we use this to answer a question he posed in 1975 on the structure of McDuff factors with .
Firm Characteristics and the Speed of FDA Approval

This paper empirically examines the effect of firm-specific characteristics on the length of time required by the Food and Drug Administration (FDA) to review and approve new-drug applications between 1990 and 1992. The approach treats regulatory decisions as endogenous and explains the variation in regulatory behavior as a function of differences that exist between firms and drugs. Results show that, controlling for drug-specific characteristics, regulators respond to firm-specific characteristics when evaluating new drug applications. For instance, firms that are less diversified and more R&D-inten-sive receive shorter review times for their new-drug applications than more diversified and less R&D-intensive firms. The reason is that most firm characteristics signal information to reviewers about either firm reputation or application quality. This information reduces reviewers' uncertainty about approving a dangerous or ineffective drug and leads to faster review times. The results suggest that regulators respond to the heterogeneities among firms in the pharmaceutical market in systematic ways.
Generalized Linear Models

In this chapter we shall discuss a class of statistical models that generalize the well-understood normal linear model. A normal or Gaussian model assumes that the response Y is equal to the sum of a linear combination X T β of the d-dimensional predictor X and a Gaussian distributed error term. It is well known that the least-squares estimator \(\hat \beta \) of β performs well under these assumptions. Moreover, extensive diagnostic tools have been developed for models of this type.
Lightning to the Empire State Building

Lightning to the Empire State Building in New York City has been under investigation since 1935. Boys camera photographs of 62 strokes have been taken and 99 oscillograms. Twenty of these were taken simultaneously with photographs of the same stroke. Upward step leaders were discovered and continuing strokes were shown to be in the nature of a direct current arc. A brief resume of the more important results up to the end of the 1937 season is given. The paper is chiefly concerned with the oscillographic results of the 1938 and 1940 seasons. The low speed oscillograph in the Empire State Building recorded 17 of the 20 strokes to the building while the high speed oscillograph recorded 41 current peaks in 13 strokes. 1. Of 49 strokes recorded oscillographically during the years 1937-40, no stroke has been entirely positive although 41, or 84 per cent, were entirely negative. The first recorded current peak in stroke 13 was positive and had a crest current of 58,000 amperes. 2. Fifty per cent of the 49 strokes had charge of 25 coulombs or more, the maximum charge measured being 164 coulombs. These values are for the total stroke and not for current peaks. 3. Ninety-one per cent of all strokes recorded to the Empire State Building are classified as continuing, i.e. had a low current component. 4.
Just do it? Investigating the gap between prediction and action in toddlers' causal inferences.

Adults’ causal representations integrate information about predictive relations and the possibility of effective intervention; if one event reliably predicts another, adults can represent the possibility that acting to bring about the first event might generate the second. Here we show that although toddlers (mean age: 24 months) readily learn predictive relationships between physically connected events, they do not spontaneously initiate one event to try to generate the second (although older children, mean age: 47 months, do; Experiments 1 and 2). Toddlers succeed only when the events are initiated by a dispositional agent (Experiment 3), when the events involve direct contact between objects (Experiment 4), or when the events are described using causal language (Experiment 5). This suggests that causal language may help children extend their initial causal representations beyond agent-initiated and direct contact events.
Testing the Gamma-Ray Burst Energy Relationships

Building on Nakar & Piran's analysis of the Amati relation relating gamma-ray burst peak energies E(sub p) and isotropic energies E(sub iso ) we test the consistency of a large sample of BATSE bursts with the Amati and Ghirlanda (which relates peak energies and actual gamma-ray energies E(sub gamma)) relations. Each of these relations can be exp ressed as a ratio of the different energies that is a function of red shift (for both the Amati and Ghirlanda relations) and beaming fraction f(sub B) (for the Ghirlanda relation). The most rigorous test, whic h allows bursts to be at any redshift, corroborates Nakar & Piran's r esult - 88% of the BATSE bursts are inconsistent with the Amati relat ion - while only l.6% of the bursts are inconsistent with the Ghirlan da relation if f(sub B) = 1. Modelling the redshift distribution resu lts in an energy ratio distribution for the Amati relation that is sh ifted by an order of magnitude relative to the observed distributions; any sub-population satisfying the Amati relation can comprise at mos t approx. 18% of our burst sample. A similar analysis of the Ghirland a relation depends sensitively on the beaming fraction distribution f or small values of f(sub B); for reasonable estimates of this distrib ution about a third of the burst sample is inconsistent with the Ghir landa relation. Our results indicate that these relations are an artifact of the selection effects of the burst sample in which they were f ound; these selection effects may favor sub-populations for which the se relations are valid.
Coulomb impurity under magnetic field in graphene: A semiclassical approach

We address the problem of a Coulomb impurity in graphene in the presence of a perpendicular uniform magnetic field. We show that the problem can be solved below the supercritical impurity magnitude within the WKB approximation. Without impurity the semiclassical energies correctly reproduce the Landau level spectrum. For a given Landau level, the WKB energy depends on the absolute value of angular momentum in a way which is consistent with the exact diagonalization result. Below the supercritical impurity magnitude, the WKB solution can be expanded as a convergent series in powers of the effective fine structure constant. Relevance of our results to the validity of the widely used Landau level projection approximation is discussed.
THE RELATIONSHIP BETWEEN THE SUDDEN CHANGE OF THE LORENTZ FORCE AND THE MAGNITUDE OF ASSOCIATED FLARES

The rapid and irreversible change of photospheric magnetic fields associated with flares has been confirmed by many recent studies. These studies showed that the photospheric magnetic fields respond to coronal field restructuring and turn to a more horizontal state near the magnetic polarity inversion line (PIL) after eruptions. Recent theoretical work has shown that the change in the Lorentz force associated with a magnetic eruption will lead to such a field configuration at the photosphere. The Helioseismic Magnetic Imager has been providing unprecedented full-disk vector magnetograms covering the rising phase of the solar cycle 24. In this study, we analyze 18 flares in four active regions, with GOES X-ray class ranging from C4.7 to X5.4. We find that there are permanent and rapid changes of magnetic field around the flaring PIL, the most notable of which is the increase of the transverse magnetic field. The changes of fields integrated over the area and the derived change of Lorentz force both show a strong correlation with flare magnitude. It is the first time that such magnetic field changes have been observed even for C-class flares. Furthermore, for seven events with associated coronal mass ejections (CMEs), we use an estimate of themore » impulse provided by the Lorentz force, plus the observed CME velocity, to estimate the CME mass. We find that if the timescale of the back reaction is short, i.e., in the order of 10 s, the derived values of CME mass ({approx}10{sup 15} g) generally agree with those reported in literature.« less
FACE ENUMERATION - FROM SPHERES TO MANIFOLDS

We prove a number of new restrictions on the enumerative properties of homology manifolds and semi-Eulerian complexes and posets. These include a determination of the affine span of the fine h-vector of balanced semi-Eulerian complexes and the toric h-vector of semi-Eulerian posets. The lower bounds on simplicial homology manifolds, when combined with higher dimensional analogues of Walkup�s 3-dimensional constructions [47], allow us to give a complete characterization of the f-vectors of arbitrary simplicial triangulations of S1 × S3 , CP2, K3 surfaces, and (S2 × S2) # (S2 × S2). We also establish a principle which leads to a conjecture for homology manifolds which is almost logically equivalent to the g-conjecture for homology spheres. Lastly, we show that with sufficiently many vertices, every triangulable homology manifold without boundary of dimension three or greater can be triangulated in a 2-neighborly fashion.
Link analysis of a deformable mirror device based optical crossbar switch

An optical crossbar switch is proposed that uses a semiconductor-addressed, deformable-mirror spatial light modulator to direct gigabit-per-second optical transmissions to several receivers. The switch performance is described in terms of size, number, and deflection range of micromechanical mirror elements, as well as emitter, detector, and lens dimensions. These parameters are incorporated in a link energy budget and estimates of system dimensions. Maximum-sized 128- to 1000-channel crossbars appear feasible based on current and projected performance limits of various lightwave components.
Subthreshold kaon production and the nuclear equation of state

Abstract We reexamine in the relativistic transport model the dependence of kaon yield on the nuclear equation of state in heavy ion collisions at energies that are below the threshold for kaon production from the nucleon-nucleon interaction in free space. For Au+Au collisions at GeV/nucleon, we find that the kaon yield measured by the Kaos collaboration at GSI can be accounted for if a soft nuclear equation of state is used. We also confirm the results obtained in non-relativistic transport models that the dependence of kaon yield on the nuclear equation of state is more appreciable in heavy ion collisions at lower incident energies. We further clarify the difference between the predictions from the relativistic transport model and the non-relativistic transport model with a momentum-dependent potential.
Structural diversity and photoluminescence of copper(I) carboxylates: From discrete complexes to infinite metal-based wires and helices

Abstract Copper(I) carboxylates have rich photoluminescent properties and broad applications in catalysis, microelectronics, and bioinorganic chemistry. They also exhibit a remarkable structural diversity ranging from discrete complexes to infinite networks based on mono-, di-, tetra-, or hexanuclear copper(I) cores, including unique double-helical arrangements. These structural variations should have important implications on physical and chemical behavior of the resulting crystalline solids, but no structural analysis or structure–property correlations have been established for this family. This work provides the first overview of the types of structures exhibited by crystallographically characterized copper(I) carboxylates having no exogenous ligands, opening pathways for a better understanding of their properties and further advancement of their practical applications.
A general synthetic strategy for 1,3-dihydro-2,1,3-benzothiadiazole 2,2-dioxides (benzosulfamides)

Abstract A general route to benzosulfamides is presented, allowing for flexible installation of substituents.
Palladium-Catalyzed Methylation and Arylation of sp2 and sp3 C−H Bonds in Simple Carboxylic Acids

The use of preformed sodium carboxylates as substrates led to the first observation of facile Pd-insertions into sp3 β-C−H bonds in simple aliphatic acids. Consequently, Pd-catalyzed methylation and arylation of o-C−H bonds in benzoic acids and β-C−H bonds in aliphatic acids using either a phenylboronate, methylboronic acid, or ArI have been achieved via a C−H activation/C−C coupling sequence.
Nuttall's theorem with analytic weights on algebraic S-contours

Given a function f holomorphic at infinity, the n th diagonal Pade approximant to f , denoted by n / n f , is a rational function of type ( n , n ) that has the highest order of contact with f at infinity. Nuttall's theorem provides an asymptotic formula for the error of approximation f - n / n f in the case where f is the Cauchy integral of a smooth density with respect to the arcsine distribution on - 1 , 1 . In this note, Nuttall's theorem is extended to Cauchy integrals of analytic densities on the so-called algebraic S-contours (in the sense of Nuttall and Stahl).
ALGEBRAIC GEOMETRIC INVARIANTS OF PARAFREE GROUPS

Given a finitely generated (fg) group G, the set R(G) of homomorphisms from G to SL2ℂ inherits the structure of an algebraic variety known as the representation variety of G in SL2ℂ. This algebraic variety is an invariant of fg presentations of G. Call a group G parafree of rank n if it shares the lower central sequence with a free group of rank n, and if it is residually nilpotent. The deviation of a fg parafree group is the difference between the minimum possible number of generators of G and the rank of G. So parafree groups of deviation zero are actually just free groups. Parafree groups that are not free share a host of properties with free groups. In this paper algebraic geometric invariants involving the number of maximal irreducible components (mirc) of R(G), and the dimension of R(G) for certain classes of parafree groups are computed. It is shown that in an infinite number of cases these invariants successfully discriminate between ismorphism types within the class of parafree groups of the same rank. This is quite surprising, since an n generated group G is free of rank n if and only if Dim(R(G)) = 3n. In fact, a trivial consequence of Theorem 1.8 in this paper is that given an arbitrary positive integer k, and any integer r ≥ 2, there exist infinitely many non-isomorphic fg parafree groups of rank r and deviation 1 with representation varieties of dimension 3r, having more than k mirc of dimension 3r. This paper also introduces many novel and surprising dimension formulas for the representation varieties of certain one-relator groups.
A microprocessor-controlled, multichannel fluorimeter for analysis of sea water

Abstract The multichannel fluorimeter described provides good sensitivity and rapid data acquisition. The advantages of multichannel fluorescence detection are discussed with special reference to the continuous monitoring of in vivo chlorophyll fluorescence in sea waters. Experiments on chlorophyll a determinations indicate a detection limit of 5 × 10 −12 M with a linear range over at least three orders of magnitudes of concentration.
BINARY QUADRATIC FORMS AND THE FOURIER COEFFICIENTS OF CERTAIN WEIGHT 1 ETA-QUOTIENTS

Abstract We state and prove an identity which represents the most general eta -products of weight 1 by binary quadratic forms. We discuss the utility of binary quadratic forms in finding a multiplicative completion for certain eta -quotients. We then derive explicit formulas for the Fourier coefficients of certain eta -quotients of weight 1 and level 47, 71, 135, 648, 1024, and 1872.
Demand sensitive energy storage in molten salts

Abstract Heat-of-fusion energy storage and on-demand steam are obtained using heat pipe techniques to transfer heat to and from stacked salt cans and onto boiler tubes within a sealed “energy storage-boiler” tank.
AGN OUTFLOWS IN A COSMOLOGICAL CONTEXT

We combine cosmological simulations with an AGN luminosity function constrained by optical surveys in order to create a realistic AGN distribution in which to model AGN outflows. The outflows are modeled with assumptions of spherical symmetry and energy conservation. We study the importance of the kinetic luminosity of AGN outflows in determining the fractional volume of the IGM filled with outflows as a function of redshift. We find that kinetic luminosities of <10% of the bolometric luminosities are required or the entire IGM would be filled with outflows at z = 0. We also examine the effects of varying the AGN lifetime and the bias parameter, which describes how tightly correlated AGNs are to high-density regions. We find that longer lifetimes (τAGN ~ 1 Gyr), as well as small bias parameters, increase the filling fraction.
Effect of Static Preloading on the Dynamic Stability of Structures

General and Model e,e = load eccentricity for the model (e = e/L) I = model moment of inertia about point A k = model spring stiffness L = model length or system position L%o = (near) stable static equilibrium position Lft = unstable static equilibrium position Iflf' = modified total potential expression UT° = total potential corresponding to static preloading U^o = total potential corresponding to total load (static + dynamic) 6 = model degree of freedom (angle) r0 = nondimensionalized, load duration, time parameter r = model nondimensionalized time parameter
Diels–Alder cycloaddition of acetylene gas to a polycyclic aromatic hydrocarbon bay region

The direct conversion of a polycyclic aromatic hydrocarbon bay region to a new, unsubstituted benzene ring by Diels–Alder cycloaddition of acetylene gas is reported for the first time. At 140 °C in dimethylformamide, under 1.8 atm pressure of acetylene gas, 7,14-dimesitylbisanthene is slowly converted to 7,14-dimesitylbenzo[ghi]bisanthene (21% conversion in 48 h).
Prospects for influencing scattering lengths with far-off-resonant light

We explore a recent proposal [Fedichev et al., Phys. Rev. Lett. 77, 2913 (1996)] for altering the mean interaction strength between ultracold atoms using an appropriately detuned laser. Although care must be taken to minimize laser-driven loss processes, we find large ranges of intensities and detunings where useful changes might be affected. Accordingly, we present simple formulas for the effects of laser light that should prove useful in designing specific experiments. We demonstrate the validity of these formulas by comparison with exact close-coupling models. In particular, we find that useful changes of the mean-field interaction require sufficiently high laser intensities that the rate of laser-induced stimulated emission exceeds the natural spontaneous emission rate.
DR21 Main: A Collapsing Cloud

The molecular cloud, DR21 Main, is an example of a large-scale gravitational collapse about an axis near the plane of the sky where the collapse is free of major disturbances due to rotation or other effects. Using flux maps, polarimetric maps, and measurements of the field inclination by comparing the line widths of ion and neutral species, we estimate the temperature, mass, magnetic field, and the turbulent kinetic, mean magnetic, and gravitational potential energies, and present a three-dimensional model of the cloud and magnetic field.
Design considerations for microprogramming languages

Historically, microprograms have been developed using tools which are appropriate to logic designers (block diagrams, register transfer languages), or systems programmers (microcode assemblers). With the growth of user microprogramming, and the increased demands placed upon computer manufacturers for firmware support, improved tools and techniques have been suggested. In particular, microprogram compilers, i.e., compilers which translate high level source statements into sequences of microprogram control words, have been proposed and implemented. The larger issue to be faced is the nebulous task of supporting the needs of a community which includes:• Manufacturers developing one particular computer (target machine) using microprogramming as a design and implementation technique.• Manufacturers developing a computer system, integrating hardware, operating systems, and programming language support, utilizing microprogramming to tie system functions together.• Users developing their own target machines tailored to applications such as computer graphics, signal processing, or interpretation of higher level languages.• Users or manufacturers who utilize hardware which is microprogrammable to directly solve one or more specific problems, without formally defining a target machine (i.e., simply programming the hardware, or host machine).
The 5-hexenyl cyclization

The cyclization of the 5-hexenyl radical to form the cyclopentylmethyl radical has been reexamined by kinetic EPR spectroscopy at temperatures between 183 and 232°K in cyclopropane solvent. The rate constant, kc for this important radical rearrangement can be represented by where Θ = 2.3RT kcal/mol.
Induction accelerator efficiency at 5 Hz

Abstract We simulate fusion power plant driver efficiency by pulsing small induction cores at 5 Hz (a typical projected power plant repetition rate), with a resistive load in the secondary winding that is scaled to simulate the beam loading for induction acceleration. Starting from a power plant driver design that is based on other constraints, we obtain the core mass and acceleration efficiency for several energy ranges of the driver accelerator and for three magnetic alloys. The resistor in the secondary is chosen to give the same acceleration efficiency, the ratio of beam energy gain to energy input to the core module (core plus acceleration gap), as was computed for the driver. The pulser consists of a capacitor switched by FETs, Field Effect Transistors, which are gated on for the desired pulse duration. The energy to the resistor is evaluated during the portion of the pulse that is adequately flat. We present data over a range of 0.6–5 μs pulse lengths. With 1 μs pulses, the acceleration efficiency at 5 Hz is measured to be 75%, 52%, and 32% for thin-tape-wound cores of nanocrystalline, amorphous, and 3% silicon steel materials respectively, including only core losses. The efficiency increases for shorter pulse durations.
The early atmosphere: a new picture.

Over the last few years, discoveries in astronomy, geochemistry, and atmospheric chemistry have resulted in a new picture of how our planet and its atmosphere formed. The traditional view held that the early atmosphere was composed of methane, ammonia, and molecular hydrogen, but the actual composition may have been nitrogen, carbon dioxide, and water vapor. The history leading to the present understanding is discussed and topics covered include: chemical evolution, origin of the atmosphere, atmospheric evolution on earth, Venus, and Mars, and prebiological atmospheric oxygen and the early sun.
Consistency and its converse: an introduction

This essay is a didactic introduction to the literature on the “consistency principle” and its “converse”. An allocation rule is consistent if for each problem in its domain of definition and each alternative that it chooses for it, then for the “reduced problem” obtained by imagining the departure of an arbitrary subgroup of the agents with their “components of the alternative” and reassessing the options open to the remaining agents, it chooses the restriction of the alternative to that subgroup. Converse consistency pertains to the opposite operation. It allows us to deduce that a rule chooses an alternative for a problem from the knowledge that for each two-agent subgroup, it chooses its restriction to the subgroup for the associated reduced problem this subgroup faces. We present two lemmas that have played a critical role in helping understand the implications of these properties in a great variety of models, the Elevator Lemma and the Bracing Lemma. We describe several applications. Finally, we illustrate the versatility of consistency and of its converse by means of a sample of characterizations based on them.
A business-oriented time-sharing system

The purpose of this project was twofold. First, to gain systems and operating experience with a remote terminal, time-sharing system. This would help to define the needs of future time-sharing applications. Second, to achieve productive use of time-sharing in some of IBM's current operations.
Endogenous matching in a market with heterogeneous principals and agents

We employ the assignment game of Shapley and Shubik (Int J Game Theory 1:111–130, 1972) to study the endogenous matching patterns in a market that consists of heterogenous principals and agents. We show that, in general, the equilibrium matching is non-assortative. We then characterize the equilibrium relationship between risk and performance pay and risk and fixed compensation. This is the first paper that characterizes the equilibrium matching, to its fullest possible extent, building on the Holmstrom and Milgrom (Econometrica 55:303–328, 1987) principal-agent model. This model has been used extensively in the empirical literature and therefore we hope that our results will be of value to empirical researchers who wish to study a principal-agent market.
Rational Versus Adaptive Expectations in Present Value Models

Using data on stock price and dividends, and on long-term and short-term interest rates, we test an important implication of present value models, that current value is a linear function of the conditional expectations of the next-period value and the current determining variable. This implication, combined with rational expectations RE, is strongly rejected. Combined with adaptive expectations AE, it is accepted. The latter model can also explain the observed negative relation between the rate of return and stock price. Thus the RE assumption should be used with caution; the AE assumption may be useful in econometric practice.
Analysis of Hamilton-Jacobi-Bellman equations arising in stochastic singular control ∗

We study the partial differential equation max{Lu − f, H(Du)} = 0 where u is the unknown function, L is a second-order elliptic operator, f is a given smooth function and H is a convex function. This is a model equation for Hamilton-Jacobi-Bellman equations arising in stochastic singular control. We establish the existence of a unique viscosity solution of the Dirichlet problem that has a Holder continuous gradient. We also show that if H is uniformly convex, the gradient of this solution is Lipschitz continuous.
Tradeoffs in Manufacturing? A Meta‐Analysis and Critique of the Literature

An ongoing, important question in the operations strategy literature pertains to tradeoffs: Can manufacturers focus on multiple priorities simultaneously or achieve strength on multiple capabilities without sacrificing performance of another? In this paper, we accumulate, integrate, and examine the wide spectrum of conclusions reached in the literature concerning tradeoffs using modified meta-analysis methods. Based on two decades of empirical research in operations strategy, we find that the evidence in the literature indicates manufacturers, on average, do not report experiencing tradeoffs among the competitive dimensions of quality, delivery, flexibility, and cost as suggested by the classical tradeoffs model. Our meta-analysis also reveals that the way variables are operationalized, whether initiatives are implemented, and the unit of analysis are all related to the degree and nature of the evidence a paper contains with respect to the tradeoffs issue. We interpret our meta-analysis results in the context of the prevailing model of manufacturing strategy and the theory of performance frontiers. We also discuss how the research designs used in this literature, which are predominantly cross-sectional, affect the nature of the evidence generated and the conclusions that can be drawn. We go on to suggest research designs that more directly assess the tradeoffs issue.
Evolutionary Processes and Paths of Relationally Embedded Network Ties in Emerging Entrepreneurial Firms

Relationally embedded network ties influence the economic decisions of emerging firms and evolve over time. Evolutionary processes and paths of these ties are examined based on two research questio...
Rates of Proton Abstraction from Conjugated Dienes in the Gas Phase

The rates of proton transfer from 2, 4-hexadiene, 1, 3-cycloheptadiene, cyclopentadiene and acetone to t-butoxide have been measured in the gas phase using pulsed-ion-cyclotron-resonance spectroscopy. The rate constants are (units of 10−10 cm3 molecule−1 s−1): 2.7 ± 0.4, 3.8 ± 0.4, 6.1 ± 0.7 and 10.8 ± 1.5, respectively. These results are analyzed in terms of the properties of the encounter complex and reaction transition states. The reaction profile for t-butoxide + cyclopentadiene is modeled using RRKM theory and an estimate for the central barrier height is obtained.
Dimensional crossover in the torque in a layered superconductor

Abstract The procedure of Bulaevskiǐ, Ledvij, and Kogan for evaluating the line energy of a single, straight vortex in the Lawrence-Doniach model in the linearized phase-only approximation is modified to take accurate account of the vortex core cross-sections. Dimensional crossover effects are found to be pronounced, with oscillations in the angular dependence of the torque for θ ⋍ π/2 and T ≈ T ∗ c .
Management of vasoocclusive pain events in sickle cell disease

Pain is the clinical hallmark of sickle cell disease (SCD). Vasoocclusive pain events (VOEs) are the primary cause of morbidity and account for most emergency department visits and hospitalizations for patients with SCD in the United States and Europe. The nature of VOE makes its management extremely challenging. There are no large controlled trials of analgesic regimens for VOE, and smaller trials have generally failed to produce an optimal course of therapy. Therefore, treatment recommendations are largely based on expert opinion and anecdotal experience. Although VOEs are not life-threatening, inadequate treatment may result in unnecessary morbidity and life-threatening complications. Health care providers caring for patients with SCD must be well informed about the management of VOE. This continuing medical education article will provide a summary of the management of acute pain events in SCD with particular emphasis on adequate analgesia.
A classification of 3R regional manipulator singularities and geometries

Abstract Using a novel geometric factorization of the singularity set, this paper enumerates all non-generic 3R manipulator geometries. These geometries divide the space of all 3R manipulator geometries into disjoint sets which have similar topological properties. Their enumeration serves as a classification scheme for all 3R manipulators. Some preliminary conjectures on 3R manipulators which can or can not change pose without passing through a singular configuration are presented as one application of these results.
Scale invariant gabor descriptor-based noncooperative iris recognition

A new noncooperative iris recognitionmethod is proposed. In this method, the iris features are extracted using a Gabor descriptor. The feature extraction and comparison are scale, deformation, rotation, and contrast-invariant. It works with off-angle and lowresolution iris images. The Gabor wavelet is incorporated with scale-invariant feature transformation (SIFT) for feature extraction to better extract the iris features. Both the phase and magnitude of the Gabor wavelet outputs were used in a novel way for local feature point description. Two feature region maps were designed to locally and globally register the feature points and each subregion in the map is locally adjusted to the dilation/contraction/deformation. We also developed a video-based noncooperative iris recognition system by integrating video-based non-cooperative segmentation, segmentation evaluation, and score fusion units. The proposed method shows good performance for frontal and off-angle iris matching. Video-based recognition methods can improve non-cooperative iris recognition accuracy.
Phylogenetic ideals and varieties for the general Markov model

The general Markov model of the evolution of biological sequences along a tree leads to a parameterization of an algebraic variety. Understanding this variety and the polynomials, called phylogenetic invariants, which vanish on it, is a problem within the broader area of Algebraic Statistics. For an arbitrary trivalent tree, we determine the full ideal of invariants for the 2-state model, establishing a conjecture of Pachter-Sturmfels. For the @k-state model, we reduce the problem of determining a defining set of polynomials to that of determining a defining set for a 3-leaf tree. Along the way, we prove several new cases of a conjecture of Garcia-Stillman-Sturmfels on certain statistical models on star trees, and reduce their conjecture to a family of subcases.
Measuring Economies of Scale and Scope in Agricultural Banking

Generally, empirical studies have used either duality theory with the estimation of cost functions or nonparametric estimation methods to assess efficiency in the financial services industry. The purpose of the present study is to estimate economies of scope and scale in agricultural banking. This will be accomplished through estimation of an indirect multi-product cost function. The uniqueness of this study, when compared to previous studies of efficiency of the financial services industry, is the disaggregation of the outputs so that agricultural lending can be evaluated. In addition, a normalized quadratic cost function is estimated with curvature properties imposed. Clark reviewed thirteen studies that measured economies of scope and scale for commercial banks, credit unions, and savings and loan associations. He found that they offered four broad conclusions: (a) overall economies of scale exist at low levels of input, (b) no consistent evid nce of economies of scope exists, (c) some evidence of cost complementarities exists, and (d) the results seem to be robust among financial institutions.
The ecological footprint of poverty alleviation: evidence from Mexico's oportunidades program.

Abstract We study the consequences of poverty-alleviation programs for environmental degradation. We exploit the community-level eligibility discontinuity for a conditional cash transfer program in Mexico to identify the impacts of income increases on deforestation and use the program's initial randomized rollout to explore household responses. We find that additional income raises consumption of land-intensive goods and increases deforestation. The observed production response and deforestation increase are larger in communities with poor road infrastructure. This suggests that better access to markets disperses environmental harm and that the full effects of poverty alleviation on the environment can be observed only where poor infrastructure localizes them.
Hierarchical mixtures of experts and the EM algorithm

We present a tree-structured architecture for supervised learning. The statistical model underlying the architecture is a hierarchical mixture model in which both the mixture coefficients and the mixture components are generalized linear models (GLIM's). Learning is treated as a maximum likelihood problem; in particular, we present an Expectation-Maximization (EM) algorithm for adjusting the parameters of the architecture. We also develop an on-line learning algorithm in which the parameters are updated incrementally. Comparative simulation results are presented in the robot dynamics domain.
Convenient construction of t-tests for quality evaluation

An available numerical approximation to the Student's t distribution is described and its use in the construction of t-tests is presented. The result is a convenient and accurate computer based approach to the selection of the sample size and critical value to be used in a t-test. Computational logic for implementation of the approach is provided and the method is illustrated by an example.
A Simple Option‐Pricing Formula

A simple option-pricing formula based on the Weibull distribution is introduced. The simplicity of the algebraic form and ease of implementation are comparable to those of Black-Scholes. Application to S&P 500 options shows that the pricing biases present in the Black-Scholes model are eliminated. Prices produced by the presented model generally lie within or close to the bid-ask spread. For long-term options (over one year), the Weibull formula exhibits significantly higher precision than the Black-Scholes formula does. While a rigorous comparison of all available models is necessary, the simplicity and precision of the proposed model are its main advantages over the existing models.
The large N limit of four dimensional Yang-Mills field coupled to adjoint fermions on a single site lattice

We consider the large N limit of four dimensional SU(N) Yang-Mills field coupled to adjoint fermions on a single site lattice. We use perturbative techniques to show that the ZN4 center-symmetries are broken with naive fermions but they are not broken with overlap fermions. We use numerical techniques to support this result. Furthermore, we present evidence for a non-zero chiral condensate for one and two Majorana flavors at one value of the lattice gauge coupling.
What Drives Stock Price Behavior Following Extreme One-Day Returns

We identify samples of losers and winners by selecting daily stock price returns in excess of 10% (sign ignored) and determine whether these samples over- or underreact. We then identify “informed” events, which correspond to announcements in the Wall Street Journal(WSJ), and “uninformed” events, which are not explained in the WSJ. For winners, there is overreaction in response to uninformed events but no overreaction on average in response to informed events. This finding suggests the degree of overreaction to new information depends on whether the cause of the extreme stock price change is publicly released.
Bounded Relay Hop Mobile Data Gathering in Wireless Sensor Networks

Recent study reveals that great benefit can be achieved for data gathering in wireless sensor networks by employing mobile collectors that gather data via short-range communications. To pursue maximum energy saving at sensor nodes, intuitively, a mobile collector should traverse the transmission range of each sensor in the field such that each data packet can be directly transmitted to the mobile collector without any relay. However, this approach may lead to significantly increased data gathering latency due to the low moving velocity of the mobile collector. Fortunately, it is observed that data gathering latency can be effectively shortened by performing proper local aggregation via multihop transmissions and then uploading the aggregated data to the mobile collector. In such a scheme, the number of local transmission hops should not be arbitrarily large as it may increase the energy consumption on packet relays, which would adversely affect the overall efficiency of mobile data gathering. Based on these observations, in this paper, we study the tradeoff between energy saving and data gathering latency in mobile data gathering by exploring a balance between the relay hop count of local data aggregation and the moving tour length of the mobile collector. We first propose a polling-based mobile gathering approach and formulate it into an optimization problem, named bounded relay hop mobile data gathering (BRH-MDG). Specifically, a subset of sensors will be selected as polling points that buffer locally aggregated data and upload the data to the mobile collector when it arrives. In the meanwhile, when sensors are affiliated with these polling points, it is guaranteed that any packet relay is bounded within a given number of hops. We then give two efficient algorithms for selecting polling points among sensors. The effectiveness of our approach is validated through extensive simulations.
The octonionic eigenvalue problem

We discuss the eigenvalue problem for 2×2 and 3×3 octonionic Hermitian matrices. In both cases, we give the general solution for real eigenvalues, and we show there are also solutions with non-real eigenvalues.