cssi/SciSciGPT-SciSciNet huggingface dataset:
Optimization of nanofluid volumetric receivers for solar thermal energy conversion

Abstract Improvements in solar-to-thermal energy conversion will accelerate the development of efficient concentrated solar power systems. Nanofluid volumetric receivers, where nanoparticles in a liquid medium directly absorb solar radiation, promise increased performance over surface receivers by minimizing temperature differences between the absorber and the fluid, which consequently reduces emissive losses. We present a combined modeling and experimental study to optimize the efficiency of liquid-based solar receivers seeded with carbon-coated absorbing nanoparticles. A one-dimensional transient heat transfer model was developed to investigate the effect of solar concentration, nanofluid height, and optical thickness on receiver performance. Simultaneously, we experimentally investigated a cylindrical nanofluid volumetric receiver, and showed good agreement with the model for varying optical thicknesses of the nanofluid. Based on the model, the efficiency of nanofluid volumetric receivers increases with increasing solar concentration and nanofluid height. Receiver-side efficiencies are predicted to exceed 35% when nanofluid volumetric receivers are coupled to a power cycle and optimized with respect to the optical thickness and solar exposure time. This work provides insights as to how nanofluids can be best utilized as volumetric receivers in solar applications, such as receivers with integrated storage for beam-down CSP and future high concentration solar thermal energy conversion systems.
Feedforward Controllers and Tracking Accuracy in the Presence of Plant Uncertainties

In the absence of plant parameter uncertainty feedforward controllers can be synthesized to achieve perfect continuous tracking. When plant has uncertainties it is, in general, impossible to achieve such perfect tracking. Investigated in this paper is the role played by feedforward controllers in the presence of plant uncertainties. We show that the use of feedforward controllers cannot improve the tracking error beyond what is achievable with a properly designed feedback loop, over all plant uncertainties. Including preview in the feedforward will not alter the situation either. We present two methods of designing robust compensators so that the tracking error due to uncertainties will be made small in some sense in the frequency domain and will have zero error in the steady state.
A concise asymmetric synthesis of the ADE fragment of nakadomarin A.

The ADE fragment of nakadomarin A has been synthesized in nine linear steps from commercial material. The key transformation is an asymmetric azomethine ylide [1,3]-dipolar cycloaddition to establish the AD-spirocyclic system containing three of the four stereocenters of the natural product.
Optimal Supersonic Ejector Designs

On developpe un modele d'ecoulement unidimensionnel de section constante pour resoudre des problemes d'optimisation d'ejecteurs supersoniques. On determine le nombre de Mach de la tuyere primaire et le rapport de section de l'ejecteur qui optimise soit le rapport d'entrainement, soit le rapport de compression, soit le rapport de pression d'arret etant donnees les valeurs des autres variables
U.S. Contributions to ITER

The United States participates in the ITER project to undertake the study of the science and technology of burning plasmas. The 2003 U.S. decision to enter the ITER negotiations followed an extensive series of community and governmental reviews of the benefits, readiness, and approaches to the study of burning plasmas. This paper describes both the technical and the organizational preparations and plans for U.S. participation in the ITER construction activity: in-kind contributions, staff contributions, and cash contributions as well as supporting physics and technology research. Near-term technical activities focus on the completion of R&D and design and mitigation of risks in the areas of provisionally assigned US contributions. Outside the project, the U.S. is engaged in preparations for the test blanket module program. Organizational activities focus on preparations of the project management arrangements to maximize the overall success of the ITER project: elements include refinement of U.S. positions on the international arrangements, the establishment of the U.S. Domestic Agency, progress along the path of the U.S. Department of Energy's Project Management Order, and overall preparations for commencement of the fabrication of major items of equipment and for provision of staff and cash as specified in the upcoming ITER agreement.
Determination of Galaxy Spin Vectors in the Pisces-Perseus Supercluster with the Arecibo Telescope

We use H I observations made with the upgraded Arecibo 305 m telescope in 1998 August to obtain accurate spin vector determinations for 54 nearly edge-on galaxies in the Minnesota Automated Plate Scanner Pisces-Perseus Survey. We introduce a simple observational technique for determining the sense of rotation for galaxies even when their H I disks are not fully resolved. We examined the spin vector distribution of these 54 galaxies for evidence of preferential galaxy alignments. We use the Kuiper statistic, a variant of the Kolmogorov-Smirnov statistic, to determine the significance of any anisotropies in the distribution of galaxy spin vectors. The possibility of "spin vector domains" is also investigated. We find no significant evidence of preferential galaxy alignments in this sample. However, we show that the small sample size places weak limits on the level of galaxy alignments.
Digital image filtering in visualized boundary layers

The application of two-dimensional low-pass matched filtering is presented for use in objective processing of digitized flow visualization images in order to identify instantaneous large-scale organized structures in turbulent boundary layers. The images were digitally acquired simultaneously with the outputs of a two-dimensional rake of hot-wire sensors in the field of view of the digital camera. Two-dimensional low wavenumber analysis brought out patterns in the visualization images which consisted of slender inclined structures having an average streamwise scale of 100-200 v/u (tau) and a length on the order of 1-2 delta. The similarly processed two-dimensional streamwise velocity reconstructions reveal similar features. The ensemble statistics indicate that these inclined features brought out by this processing may be a basic flow module in higher Reynolds number flows which links the so-called wall 'bursting' process and the larger outer scale motions.
Comments on A, B, C chains of heterotic and Type II vacua

Abstract We construct, as hypersurfaces in toric varieties, Calabi-Yau manifolds corresponding to F-theory vacua dual to E 8 × E 8 heterotic strings compactified to six dimensions on K 3 surfaces with non-semisimple gauge backgrounds. These vacua were studied in the recent work of Aldazabal, Font, Ibanez and Uranga as well as by Klemm, Mayr and Vafa. We extend their results by constructing many more examples, corresponding to enhanced gauge symmetries, by noting that they can be obtained from previously known Calabi-Yau manifolds corresponding to K 3 compactification of heterotic strings with simple gauge backgrounds by means of extremal transitions of the conifold type.
Differentially private data analysis of social networks via restricted sensitivity

We introduce the notion of restricted sensitivity as an alternative to global and smooth sensitivity to improve accuracy in differentially private data analysis. The definition of restricted sensitivity is similar to that of global sensitivity except that instead of quantifying over all possible datasets, we take advantage of any beliefs about the dataset that a querier may have, to quantify over a restricted class of datasets. Specifically, given a query f and a hypothesis HH about the structure of a dataset D, we show generically how to transform f into a new query fHH whose global sensitivity (over all datasets including those that do not satisfy HH) matches the restricted sensitivity of the query f. Moreover, if the belief of the querier is correct (i.e., D ∈ HH) then fHH(D) = f(D). If the belief is incorrect, then fHH(D) may be inaccurate.We demonstrate the usefulness of this notion by considering the task of answering queries regarding social-networks, which we model as a combination of a graph and a labeling of its vertices. In particular, while our generic procedure is computationally inefficient, for the specific definition of H as graphs of bounded degree, we exhibit efficient ways of constructing fH using different projection-based techniques. We then analyze two important query classes: subgraph counting queries (e.g., number of triangles) and local profile queries (e.g., number of people who know a spy and a computer-scientist who know each other). We demonstrate that the restricted sensitivity of such queries can be significantly lower than their smooth sensitivity. Thus, using restricted sensitivity we can maintain privacy whether or not D ∈ HH, while providing more accurate results in the event that HH holds true.
Confocal Fluorescence Microscopy Using a Microfabricated Zone Plate

We demonstrate a compact confocal fluorescence microscope using a microfabricated zone plate. Using a single fluorescent sphere, we measure the transverse and axial resolution to be below 1.6 and 2.2 micron, respectively.
Aerodynamic Performance of Extended Formation Flight

The aerodynamic benefits of formation flight have been known for nearly a century. However, these benefits have yet to be realized in a commercial environment in part due to the hazards associated with close formation flight. This paper explores amorepractical approach to formationflight called extended formationflight,which takes advantage of the persistence of cruise wakes and extends the streamwise spacing between the aircraft by at least 10 spans. Induced-drag savings are estimated in an incompressible analysis considering the effects of wake rollup, vortex decay, vortex instabilities, vortex motion, atmospheric turbulence and stratification, and stochastic behavior. Extended formations are found to be unpractical for streamwise spacings larger than about 40 spans between each aircraft. For spacings around 10 to 40 spans, with low to moderately low atmospheric turbulence, a two-aircraft formation has a maximum induced-drag reduction of 30 3%, while a three-aircraft formation has a maximum induced-drag reduction of 40 6%. At these distances, aircraft tracking error is themost significant contribution to the variation in drag savings. Studies of transonic effects, ride quality concerns, and control and sensing strategies are necessary to further evaluate the potential of extended formation flight.
A regularized solution to edge detection

We consider edge detection as the problem of measuring and localizing changes of light intensity in the image. As discussed by Torre and Poggio (1984), edge detection, when defined in this way, is an ill-posed problem in the sense of Hadamard. The regularized solution that arises is then the solution to a variational principle. In the case of exact data, one of the standard regularization methods (see Poggio and Torre, 1984) leads to cubic spline interpolation before differentiation. We show that in the case of regularly-spaced data this solution corresponds to a convolution filter--- to be applied to the signal before differentiation -- which is a cubic spline. In the case of non-exact data, we use another regularization method that leads to a different variational principle. We prove (1) that this variational principle leads to a convolution filter for the problem of one- dimensional edge detection, (2) that the form of this filter is very similar to the Gaussian filter, and (3) that the regularizing parameter $\lambda$ in the variational principle effectively controls the scale of the filter.
Hypercritical Advection-dominated Accretion Flow

In this paper we study the accretion disk that arises in hypercritical accretion of ~ 108 MEdd onto a neutron star while it is in common envelope evolution with a massive companion. Such a study was carried out by Chevalier, who had earlier suggested that the neutron star would go into a black hole in common envelope evolution. In his later study he found that the accretion could possibly be held up by angular momentum. In order to raise the temperature high enough that the disk might cool by neutrino emission, Chevalier found a small value of the α-parameter, where the kinematic coefficient of shear viscosity is ν = αcsH, with cs the velocity of sound and H the disk height; namely, α ~ 10-6 was necessary for gas pressure to dominate. He also considered results with higher values of α, pointing out that radiation pressure would then predominate. With these larger α-values, the temperatures of the accreting material are much lower, 0.35 MeV. The result is that neutrino cooling during the flow is negligible, satisfying very well the advection-dominating conditions. The low temperature of the accreting material means that it cannot get rid of its energy rapidly by neutrino emission, so it piles up, pushing its way through the accretion disk. An accretion shock is formed, far beyond the neutron star, at a radius 108 cm, much as in the earlier spherically symmetric calculation, but in rotation. Two-dimensional numerical simulation shows that an accretion disk is reformed inside of the accretion shock, allowing matter to accrete onto the neutron star with pressure high enough so that neutrinos can carry off the energy.
Cyclopentadienyl thiocarbonyl complexes of iron: [Cp★Fe(CO)2CS]+, Cp★2Fe2(CO)2(CS)2, Cp2Fe2(CO)3(CS), and Cp2Fe2(CO)2(CS)2

Abstract Nucleophiles generally react with the new iron thiocarbonyl complex [Cp ★ Fe(CO) 2 (CS)] + (Cp ★ = η-C 5 Me 5 ) by attacking at the carbon of the CS ligand. Thus, SMe − gives the dithioester, Cp ★ Fe(CO) 2 [(CS)SMe] and N 3 − gives N-bound thiocyanate, Cp ★ Fe(CO) 2 (NCS). It is observed that MeO − attacks initially at the carbon of the CO ligand but more slowly migrates to the carbon of the CS ligand giving Cp ★ Fe(CO) 2 [C(S)OMe]. The reaction of the thioesters with MeOSO 2 CF 3 yields the thiocarbene complexes, {Cp ★ (CO) 2 Fe[C(SMe)X]} + (X = OMe, SMe). The thiocarbonyl dimer, Cp ★ 2 Fe 2 (CO) 2 (CS) 2 , is synthesized by reduction of [Cp ★ Fe(CO) 2 (CS)] + with NaH. Reactions of Cp 2 Fe 2 (CO) 3 (CS) and Cp 2 Fe 2 (CO) 2 (CS) 2 with Raney Ni result in the conversion of the bridging CS ligands to μ-CH 2 groups in the complexes Cp 2 Fe 2 (CO) 3 (μ-CH 2 ), Cp 2 Fe 2 (CO) 2 (CS)(μ-CH 2 ) and Cp 2 Fe 2 (CO) 2 (μ-CH 2 ) 2 . The thiocarbonyl dimers also react with AgBF 4 to give [Cp 2 Fe 2 (CO) 2 (CS) 2 ]Ag + BF 4 − and {[Cp 2 Fe 2 (CO) 3 (CS)] 3 Ag}BF 4 ; the structure of the latter compound was determined by X-ray crystallography.
The effect of banking crises on deposit growth: State-level evidence from 1900 to 1930

Using a newly constructed database of bank failures for the period 1900 to 1930, this paper estimates a dynamic regression model to examine the extent to which banking instability at the state level affects the proportion of state deposits relative to national deposits. The main results indicate that banking failures reduce the proportion of state deposits by approximately 0.04% in the short run and by nearly 1% in the long run. In the eight states that adopted deposit insurance systems during the 1910s, however, there is little evidence that banking crises affected deposit growth. In addition, there is no evidence that the banking crisis of the 1980s and 1990s had any significant effect on state deposit growth. These results suggest that deposit insurance may have lessened the effects of banking instability on deposit growth.
The Disjunction Effect and Reason-Based Choice in Games.

Abstract This paper reports an experiment that extends previous find ings of the disjunction effect, sometimes described as a violation of Savage's sure-thing principle. Evidence of the disjunction ef fect is observed using elicited beliefs about others' actions (rather than controlled beliefs) in a prisoners' dilemma studied by Shafir and Tversky (1992) as well as in an asymmetric version of it and in a nondilemma game with a unique equilibrium. Debiasing tech niques as well as implications for these extensions are discussed.
Income and Health in Cities: the Messages from Stylized Facts

The benefits of good health to individuals and to society are strongly positive, and improving the health of the poor is a key millennium development goal (MDG). A typical health strategy advocated by some calls for increased public spending on health targeted to favor the poor backed by foreign assistance, combined with an international effort to perfect drugs and vaccines to ameliorate the major infectious diseases prevalent in developing nations. However, if the objective is better health outcomes at the least cost and a reduction in urban health inequity, our research suggests that the four most potent policy interventions are: improving access to clean water and sanitation; widely available primary care and health programs aimed at influencing diets and lifestyles; raising the level of education; and better urban land use and transport planning which contains urban sprawl and minimizes the trend towards sedentary living habits. The payoff from these four, in terms of health outcomes especially for those in low-income categories, dwarfs the returns from new drugs and curative hospital-based medicine, although these certainly have their place in a modern urban health system. We find, moreover, that the resource requirements for successful health care policies are likely to depend on an acceleration of economic growth rates, which increase household purchasing power and enlarge the pool of resources available to national and subnational governments to invest in and maintain health-related infrastructure and services. Thus, an acceleration of growth rates may be necessary to sustain a viable urban health strategy, which is equitable, and to ensure steady gains in health outcomes.
NMR assignments for the aldopentoses

Abstract The 1 H and 13 C NMR assignments for the simple aldopentopyranoses in 2 H 2 O were made using high field 2D NMR spectroscopy. The furanose forms of ribose were also tentatively assigned. The 2D techniques used to assign the resonances include the HMQC, HMBC, 2QF-COSY, TOCSY, 2Q, and INADEQUATE experiments. Selective 1D TOCSY experiments were also necessary to assign the crowded proton spectrum of ribose.
Rhodium(I)-Catalyzed Allenic Carbocyclization Reaction Affording δ- and ε-Lactams

This letter extends the scope of the rhodium(I)-catalyzed allenic Alder-ene carbocyclization reaction to the preparation of δ- and e-lactams from amides. A variety of allenic propiolamides were cycloisomerized to give a number of unsaturated δ-lactams. In addition, allenic propargylamides give good yields of the corresponding e-lactams. Formation of lactams possessing these ring sizes has rarely been accomplished via transition-metal-catalyzed carbon−carbon bond forming strategies. Thus, this approach provides an alternative strategy for synthesizing these substructures.
Correlation of nosetip boundary-layer transition data measured in ballistics-range experiments

Preablated nosetips of various carbonaceous materials were tested in a ballistics range. Surface-temperature contours, measured with image-converter cameras, were used to define boundary-layer transition-front contours. Measurements of surface roughness, surface temperature, average transition-front location, and freestream environment were combined with calculations of nosetip flowfields, and with calculations of laminar boundary-layer development in these flowfields, to transform all data into various dimensionless parameters. These parameters were defined by previous attempts to correlate existing wind-tunnel data for transition on rough/blunt bodies. Of the available correlating techniques, only one, based on the concept of a constant (critical) roughness Reynolds number for transition, was found to successfully describe both the wind-tunnel and ballistics-range data, thereby validating the extrapolation of this concept to actual re-entry vehicle materials and environments.
Dynamic pull-in of parallel-plate and torsional electrostatic MEMS actuators

An analysis of the dynamic characteristics of pull-in for parallel-plate and torsional electrostatic actuators is presented. Traditionally, the analysis for pull-in has been done using quasi-static assumptions. However, it was recently shown experimentally that a step input can cause a decrease in the voltage required for pull-in to occur. We propose an energy-based solution for the step voltage required for pull-in that predicts the experimentally observed decrease in the pull-in voltage. We then use similar energy techniques to explore pull-in due to an actuation signal that is modulated depending on the sign of the velocity of the plate (i.e., modulated at the instantaneous mechanical resonant frequency). For this type of actuation signal, significant reductions in the pull-in voltage can theoretically be achieved without changing the stiffness of the structure. This analysis is significant to both parallel-plate and torsional electrostatic microelectromechanical systems (MEMS) switching structures where a reduced operating voltage without sacrificing stiffness is desired, as well as electrostatic MEMS oscillators where pull-in due to dynamic effects needs to be avoided
Lessons learned from a part-time worker typology applied to full-timers

Purpose – Research on work status differences has yielded inconsistent results and is not relevant for today's workforce, economic circumstances, or the changing nature of work. Inconsistencies may be due to substantial heterogeneity, rather than homogeneity, within each group (part-time (PT) and full-time (FT)). Thus, researchers created a PT worker typology based on demographics and personal life roles. Systematic differences in attitudes and behaviors across derived groups of PT workers were found. The purpose of the current study is to test the applicability of this PT worker typology on FT workers and to extend the typology's foundational theory, partial inclusion theory (PIT). Design/methodology/approach – The current study employs cluster analysis on three diverse samples (n=3,747) to establish a basis for the generalizability of the FT typology. Findings – Strong support was found for a similar, but distinct, FT employee typology. Attitudinal and behavioral differences were also found among the va...
Large deviations and moments for the Euler characteristic of a random surface

We study random surfaces constructed by glueing together N-k filled k-gons along their edges, with all (N - 1)ee = (N - 1)(N - 3)···3 · 1 pairings of the edges being equally likely. (We assume that lcml2,kr divides N.) The Euler characteristic of the resulting surface is related to the number of cycles in a certain random permutation of l1,…,Nr. Gamburd has shown that when 2 lcml2,kr divides N, the distribution of this random permutation converges to that of the uniform distribution on the alternating group AN in the total-variation distance as N → ∞. We obtain large-deviations bounds for the number of cycles that, together with Gamburd's (Ann Probab 34 (2006), 1827–1848) result, allow us to derive sharp estimates for the moments of the number of cycles. These estimates allow us to confirm certain cases of conjectures made by Pippenger and Schleich (Random Struct Algorithm 28 (2006), 247–288). © 2010 Wiley Periodicals, Inc. Random Struct. Alg., 2010
Variation of Vacuum Energy if Scale Factor Becomes Infinitely Small, with Fixed Entropy Due to a Non Pathological Big Bang Singularity Accessible to Modified Einstein Equations

When initial radius Rinitial 0 if Stoica actually derived Einstein equations in a formalism which remove the big bang singularity pathology, then the reason for Planck length no longer holds. The implications of Rinitial 0 are the first part of this manuscript. Then the resolution is alluded to by work from Muller and Lousto, as to implications of entanglement entropy. We present entanglement entropy in the early universe with a steadily shrinking scale factor, due to work from Muller and Lousto, and show that there are consequences due to initial entanged Sentropy=0.3rH2/a2 for a time dependent horizon radius rH in cosmology, with for flat space conditions rH= for conformal time. In the case of a curved, but not flat space version of entropy, we look at vacuum energy as proportional to the inverse of scale factor squared times the inverse of initial entropy, effectively when there is no initial time in line with ~H2/G H≈a-1. The consequences for this initial entropy being entangled are elaborated in this manuscript. No matter how small the length gets, Sentropy if it is entanglement entropy, will not go to zero. The requirement is that the smallest length of time, t, re scaled does not go to zero. Even if the length goes to zero. This preserves a minimum non zero vacuum energy, and in doing so keep the bits, for computational bits cosmological evolution even if Rinitial 0.
Palladium(II) catalyzed carbonylation of ketones

Abstract Cyclic ketones react with PdCl2 in methanol under a CO atmosphere to give mainly diesters by a ring cleavage reaction along with some chloro-substituted monoester. 13CO labeling experiments indicate the major product is formed by a mechanism involving Pd(II)-CO2CH3 insertion across the double bond of the enol form of the ketone. Pd(II) elimination and acid-catalyzed ring cleavage form a second methyl ester group.
Coding versus ARQ in Fading Channels: How Reliable Should the PHY Be?

This paper studies the tradeoff between channel coding and ARQ (automatic repeat request) in Rayleigh block-fading channels. A heavily coded system corresponds to a low transmission rate with few ARQ re-transmissions, whereas lighter coding corresponds to a higher transmitted rate but more retransmissions. The optimum packet error probability, where optimum refers to the maximization of the average successful throughput, is derived and is shown to be a decreasing function of the average signal-to-noise ratio and of the channel diversity order. A general conclusion of the work is that the optimum error probability is quite large (e.g., 10% or larger) for reasonable channel parameters, and that operating at a very small error probability can lead to a significantly reduced throughput. This conclusion holds even when a number of practical ARQ considerations, such as delay constraints and acknowledgement feedback errors, are taken into account.
Strategic Tax and Financial Reporting Decisions: Theory and Evidence*

This paper examines the effect of book-tax differences on the probability that a transaction is audited and the probability that additional taxes are collected. It constructs a stylized model in which the taxpayer reports both financial accounting income and taxable income. The government observes both reports before deciding whether to conduct an audit. The analysis of the equilibrium yields two hypotheses. First, the probability that the government will audit a transaction is higher if the transaction generates a positive book-tax difference (e.g., an expenditure that is deducted for tax purposes but capitalized for financial reporting purposes) than if the transaction generates no book-tax difference. Second, conditional on being selected for audit, transactions with and without book-tax differences are equally likely to have detected understatements of tax liability. These hypotheses are tested using Internal Revenue Service (IRS) data from the Coordinated Examination Program. The empirical tests are consistent with the predictions of the strategic tax compliance model.
Parametric instabilities and plasma heating in an inhomogeneous plasma

Experimental studies of plasma heating due to microwave irradiation of the magnetically confined plasma column in the Princeton L-3 device is presented. X-band (10.4 GHz) microwave power, both in the ordinary and the extraordinary modes of propagation, is used in these experiments. Plasma heating is observed to occur simultaneously with the occurrence of parametric decay instabilities. The mode structure of the pump wave and the decay ion wave dispersion have been measured with high frequency probes. Detailed measurements of electron heating rates are presented and compared with collisional heating rates. In addition, production of suprathermal electrons and ions is also observed and measured. A comparison is made with recent laser-pellet interaction experiments.
Circle actions on C*-algebras, partial automorphisms, and a generalized Pimsner-Voiculescu exact sequence

Abstract We introduce a method to study C *-algebras possessing an action of the circle group, from the point of view of their internal structure and their K -theory. Under relatively mild conditions our structure theorem shows that any C *-algebra, where an action of the circle is given, arises as the result of a construction that generalizes crossed products by the group of integers. Such a generalized crossed product construction is carried out for any partial automorphism of a C *-algebra, where by a partial automorphism we mean an isomorphism between two ideals of the given algebra. Our second main result is an extension to crossed products by partial automorphisms, of the celebrated Pimsner-Voiculescu exact sequence for K -groups. The representation theory of the algebra arising from our construction is shown to parallel the representation theory for C *-dynamical systems. In particular, we generalize several of the main results relating to regular and covariant representations of crossed products.
On the relationship between stress and elastic strain for porous and fractured rock

Abstract Modeling the mechanical deformations of porous and fractured rocks requires a stress–strain relationship. Experience with inherently heterogeneous earth materials suggests that different varieties of Hooke's law should be applied within regions of the rock having significantly different stress–strain behavior. We apply this idea by dividing a rock body conceptually into two distinct parts. The natural strain (volume change divided by rock volume at the current stress state), rather than the engineering strain (volume change divided by the unstressed rock volume), should be used in Hooke's law for accurate modeling of the elastic deformation of that part of the pore volume subject to a relatively large degree of relative deformation (i.e., cracks or fractures). This approach permits the derivation of constitutive relations between stress and a variety of mechanical and/or hydraulic rock properties. We show that the theoretical predictions of this method are generally consistent with empirical expressions (from field data) and also laboratory rock experimental data.
High Distance Heegaard Splittings via Dehn Twists

In 2001, J Hempel proved the existence of Heegaard splittings of arbitrarily high distance by using a high power of a pseudo-Anosov map as the gluing map between two handlebodies. We show that lower bounds on distance can also be obtained when using a high power of a suitably chosen Dehn twist. In certain cases, we can then determine the exact distance of the resulting splitting. These results can be seen as a natural extension of work by A Casson and C Gordon in 1987 regarding strongly irreducible Heegaard splittings. 57M50; 57M25
Development of Quantitative Metrics for Second-Harmonic Generation Imaging of Collagen-Based Structures

We discuss the application of harmonic analysis in second-harmonic generation microscopy in developing useful quantitative metrics for assessing tissue morphology. A comparison between the information content in forward and backward SHG images is also presented.
Synthesis of angularly-fused aromatic antibiotics. Preparation of the ABC ring system of aquayamycin

Abstract An approach to the ABC ring system of aquayamycin which incorporates a selectively protected cis-diol unit is described. The key step is an intramolecular addition of the anion of a protected cyanohydrin to a ketone.
Singularities of generic projection hypersurfaces

Linearly projecting smooth projective varieties provide a method of obtaining hypersurfaces birational to the original varieties. We show that in low dimension, the resulting hypersurfaces only have Du Bois singularities. Moreover, we conclude that these Du Bois singularities are in fact semi log canonical. However, we demonstrate the existence of counterexamples in high dimension - the generic linear projection of certain varieties of dimension 30 or higher is neither semi log canonical nor Du Bois.
Compressed-liquid density measurements of three alternative turbine fuels

Compressed-liquid densities of three alternative turbine fuels have been measured with a vibrating U-tube densimeter. The measurements were made from 270 K to 470 K, and 0.5 MPa to 50 MPa and have an overall combined uncertainty of 0.81 kg m−3. Each of the fuels was derived from a very different source; one from hydroprocessed chicken fat, the second from the dimerized components of crude turpentine, and the third was synthesized from natural gas in a Fischer–Tropsch process. The data have been correlated with a Tait equation within their experimental uncertainty. Equation parameters are given for each fuel. Results of the measurements presented here are compared with previously measured densities of Jet-A, JP-8 and JP-10.
Theory of electron-positron showers in double radio sources

A black hole of mass approx.3 x 10/sup 8/ M/sub sun/ is assumed to be present in the nucleus of an active galaxy or quasar. With an axial magnetic field approx.10/sup 3/ gauss, a potential drop approx.10/sup 19/ volts is generated by the unipolar induction of a rotating accretion disk surrounding the black hole. Here, we investigate the possibility that the acceleration of electrons or positrons in the unipolar fields initiates an electromagnetic cascade shower at distances > or approx. =10/sup 16/ cm from the black hole. The scattering medium for the shower is considered to be the spectrum of low energy photons originating from the inner region of the disk. It is found that at completion of the cascade, power-law energy spectra of relativistic electrons and positrons and of ..gamma..-rays emerge under appropriate conditions. If the cascade-initiating particles are collimated, the electrons and positrons (and the ..gamma..-rays) emerge in a collimated beam. Such beams may power extragalactic double radio sources.
Probing solar and stellar interior dynamics and dynamo

Abstract Solar and stellar activity is a result of complex interaction between magnetic field, turbulent convection and differential rotation in a star’s interior. Magnetic field is believed to be generated by a dynamo process in the convection zone. It emerges on the surface forming sunspots and starspots. Localization of the magnetic spots and their evolution with the activity cycle is determined by large-scale interior flows. Thus, the internal dynamics of the Sun and other stars hold the key to understanding the dynamo mechanism and activity cycles. Recently, significant progress has been made for modeling magnetohydrodynamics of the stellar interiors and probing the internal rotation and large-scale dynamics of the Sun by helioseismology. Also, asteroseismology is beginning to probe interiors of distant stars. I review key achievements and challenges in our quest to understand the basic mechanisms of solar and stellar activity.
Extremal solutions of inequations over lattices with applications to supervisory control

We study the existence and computation of extremal solutions of a system of inequations defined over lattices. Using the Knaster-Tarski fixed point theorem, we obtain sufficient conditions for the existence of supremal as well as infimal solution of a given system of inequations. Iterative techniques are presented for the computation of the extremal solutions whenever they exist, and conditions under which the termination occurs in a single iteration are provided. These results are then applied for obtaining extremal solutions of various inequations that arise in computation of maximally permissive supervisors in control of logical discrete event systems (DESs) first studied by Ramadge and Wonham. Thus our work presents a unifying approach for computation of supervisors in a variety of situations.
Exploring synchronization in complex oscillator networks

The emergence of synchronization in a network of coupled oscillators is a pervasive topic in various scientific disciplines ranging from biology, physics, and chemistry to social networks and engineering applications. A coupled oscillator network is characterized by a population of heterogeneous oscillators and a graph describing the interaction among the oscillators. These two ingredients give rise to a rich dynamic behavior that keeps on fascinating the scientific community. In this article, we present a tutorial introduction to coupled oscillator networks, we review the vast literature on theory and applications, and we present a collection of different synchronization notions, conditions, and analysis approaches. We focus on the canonical phase oscillator models occurring in countless real-world synchronization phenomena, and present their rich phenomenology. We review a set of applications relevant to control scientists. We explore different approaches to phase and frequency synchronization, and we present a collection of synchronization conditions and performance estimates. For all results we present self-contained proofs that illustrate a sample of different analysis methods in a tutorial style.
Boson-fermion confusion: the string path to supersymmetry

Abstract Reminiscences on the String origins of Supersymmetry are followed by a discussion of the importance of confusing bosons with fermions in building superstring theories in 9 + 1 dimensions. In eleven dimensions, the kinship between bosons and fermions is more subtle, and may involve the exceptional group F4.
Using Extended Genealogy to Estimate Components of Heritability for 23 Quantitative and Dichotomous Traits

Important knowledge about the determinants of complex human phenotypes can be obtained from the estimation of heritability, the fraction of phenotypic variation in a population that is determined by genetic factors. Here, we make use of extensive phenotype data in Iceland, long-range phased genotypes, and a population-wide genealogical database to examine the heritability of 11 quantitative and 12 dichotomous phenotypes in a sample of 38,167 individuals. Most previous estimates of heritability are derived from family-based approaches such as twin studies, which may be biased upwards by epistatic interactions or shared environment. Our estimates of heritability, based on both closely and distantly related pairs of individuals, are significantly lower than those from previous studies. We examine phenotypic correlations across a range of relationships, from siblings to first cousins, and find that the excess phenotypic correlation in these related individuals is predominantly due to shared environment as opposed to dominance or epistasis. We also develop a new method to jointly estimate narrow-sense heritability and the heritability explained by genotyped SNPs. Unlike existing methods, this approach permits the use of information from both closely and distantly related pairs of individuals, thereby reducing the variance of estimates of heritability explained by genotyped SNPs while preventing upward bias. Our results show that common SNPs explain a larger proportion of the heritability than previously thought, with SNPs present on Illumina 300K genotyping arrays explaining more than half of the heritability for the 23 phenotypes examined in this study. Much of the remaining heritability is likely to be due to rare alleles that are not captured by standard genotyping arrays.
Bayesian Photometric Redshift Estimation

Photometric redshifts are quickly becoming an essential tool of observational cosmology, although their utilization is somewhat hindered by certain shortcomings of the existing methods, e.g., the unreliability of maximum-likelihood techniques or the limited application range of the "training-set" approach. The application of Bayesian inference to the problem of photometric redshift estimation effectively overcomes most of these problems. The use of prior probabilities and Bayesian marginalization facilitates the inclusion of relevant knowledge, such as the expected shape of the redshift distributions and the galaxy type fractions, which can be readily obtained from existing surveys but are often ignored by other methods. If this previous information is lacking or insufficient—for instance, because of the unprecedented depth of the observations—the corresponding prior distributions can be calibrated using even the data sample for which the photometric redshifts are being obtained. An important advantage of Bayesian statistics is that the accuracy of the redshift estimation can be characterized in a way that has no equivalents in other statistical approaches, enabling the selection of galaxy samples with extremely reliable photometric redshifts. In this way, it is possible to determine the properties of individual galaxies more accurately, and simultaneously estimate the statistical properties of a sample in an optimal fashion. Moreover, the Bayesian formalism described here can be easily generalized to deal with a wide range of problems that make use of photometric redshifts. There is excellent agreement between the ≈130 Hubble Deep Field North (HDF-N) spectroscopic redshifts and the predictions of the method, with a rms error of Δz ≈ 0.06(1 + zspec) up to z < 6 and no outliers nor systematic biases. It should be remarked that since these results have not been reached following a training-set procedure, the above value of Δz should be a fair estimate of the expected accuracy for any similar sample. The method is further tested by estimating redshifts in the HDF-N but restricting the color information to the UBVI filters; the results are shown to be significantly more reliable than those obtained with maximum-likelihood techniques.
Equivariant isospectrality and Sunada’s method

We construct pairs and continuous families of isospectral yet locally non-isometric orbifolds via an equivariant version of Sunada’s method. We also observe that if a good orbifold \({\mathcal{O}}\) and a smooth manifold M are isospectral, then they cannot admit non-trivial finite Riemannian covers \({M_1 \to\mathcal{O}}\) and M2 → M where M1 and M2 are isospectral manifolds.
(0,2) Landau-Ginzburg theory

Abstract A large class of (0,2) Calabi-Yau σ-models and Landau-Ginzburg orbifolds are shown to arise as different “phases” of supersymmetric gauge theories. We find a phenomenon in the Landau-Ginzburg phase which may enable one to understand which Calabi-Yau σ-models evade destabilization by worldsheet instantons. Examples of (0,2) Landau-Ginzburg vacua are analyzed in detail, and several novel features of (0,2) models are discussed. In particular, we find that (0,2) models can have different quantum symmetries from the (2,2) models built on the same Calabi-Yau manifold, and that a new kind of topology change can occur in (0,2) models of string theory.
Empirical Evidence Against CAPM: Relating Alphas and Returns to Betas

One of the consequences of the capital asset pricing model (CAPM) is that the expected excess return of a financial instrument is proportional to the expected excess market return. The proportionality constant, called the instrument's beta, is the coefficient in the linear least-squares fit of the excess return of the instrument with the excess return of the market. CAPM therefore implies that stocks with larger empirical estimates of beta will tend to produce larger returns. We analyze this hypothesis using the stock return data for the S&P 500 constituents from 1966 to 2010. We obtain several statistically significant results inconsistent with the hypothesis. These inconsistencies are much less pronounced during the last two decades of our dataset than before 1990.
Comparative analysis of regulatory information and circuits across distant species

Despite the large evolutionary distances between metazoan species, they can show remarkable commonalities in their biology, and this has helped to establish fly and worm as model organisms for human biology. Although studies of individual elements and factors have explored similarities in gene regulation, a large-scale comparative analysis of basic principles of transcriptional regulatory features is lacking. Here we map the genome-wide binding locations of 165 human, 93 worm and 52 fly transcription regulatory factors, generating a total of 1,019 data sets from diverse cell types, developmental stages, or conditions in the three species, of which 498 (48.9%) are presented here for the first time. We find that structural properties of regulatory networks are remarkably conserved and that orthologous regulatory factor families recognize similar binding motifs in vivo and show some similar co-associations. Our results suggest that gene-regulatory properties previously observed for individual factors are general principles of metazoan regulation that are remarkably well-preserved despite extensive functional divergence of individual network connections. The comparative maps of regulatory circuitry provided here will drive an improved understanding of the regulatory underpinnings of model organism biology and how these relate to human biology, development and disease.
Sexual Activity and Function in Postmenopausal Women With Heart Disease

Objective: To examine the prevalence and correlates of sexual activity and function in postmenopausal women with heart disease. Methods: We included baseline self-reported measures of sexual activity and the sexual problem scale from the Medical Outcomes Study in the Heart and Estrogen/Progestin Replacement Study (HERS), a study of 2,763 postmenopausal women, average age 67 years, with coronary disease and intact uteri. We used multivariable linear and logistic regression to identify independent correlates of sexual activity and dysfunction. Results: Approximately 39% of the women in HERS were sexually active, and 65% of these reported at least 1 of 5 sexual problems (lack of interest, inability to relax, difficulty in arousal or in orgasm, and discomfort with sex). In multivariable analysis, factors independently associated with being sexually active included younger age, fewer years since menopause, being married, better self-reported health, higher parity, moderate alcohol use, not smoking, lack of chest discomfort, and not being depressed. Among the 1,091 women who were sexually active, lower sexual problem scores were associated with being unmarried, being better educated, having better self-reported health, and having higher body mass index. Conclusion: Many women with heart disease continue to engage in sexual activity into their 70s, and two thirds of these report discomfort and other sexual function problems. Physicians should be aware that postmenopausal patients are sexually active and address the problems these women experience. (Obstet Gynecol 2005;106:121–7) Level of Evidence: II-2
Discrete-event control of nondeterministic systems

Nondeterminism in discrete-event systems occurs in many practical situations and often as a result of partial observability of events. For the adequate description of nondeterministic systems and nondeterministic phenomena, the trajectory-model formalism was introduced by Heymann (1991) and Heymann et al. (1991). This formalism has been used in by Shayman et al. (1995) for obtaining various results on supervisory control of nondeterministic systems subject to language specifications. In the present paper we develop a theory of supervisory control for nondeterministic discrete-event systems subject to both language and trajectory-model specifications. We further show how well-known algorithms for supervisory control (of deterministic systems) under partial observation can be adapted for synthesis of supervisors for nondeterministic systems subject to both language and trajectory-model specifications.