cssi/SciSciGPT-SciSciNet huggingface dataset:
Application of robust control to sustained oscillations in power systems

Transient control of the sustained oscillations that can occur after a major disturbance to a power system is investigated. A control scheme for an n-generator system is first developed using a classical machine model, and then extended to a machine model that includes governor/turbine dynamics. The proposed control strategies are linear and require only local relative angle and velocity measurements for the classical model case, plus the measurement of mechanical power if governor/turbine dynamics are included. Using Lyapunov's direct method, the control is shown to be robust with respect to parameter and load variations, and topology changes in the power system. The overall power system is shown to be exponentially stable in the main so that any oscillation, anywhere in the system, can be damped efficiently. The results are obtained without any linearization of the power system model. Simulation results for the 30-bus New England system demonstrate the effectiveness of the proposed control. >
Mn3O4−Graphene Hybrid as a High-Capacity Anode Material for Lithium Ion Batteries

We developed two-step solution-phase reactions to form hybrid materials of Mn(3)O(4) nanoparticles on reduced graphene oxide (RGO) sheets for lithium ion battery applications. Selective growth of Mn(3)O(4) nanoparticles on RGO sheets, in contrast to free particle growth in solution, allowed for the electrically insulating Mn(3)O(4) nanoparticles to be wired up to a current collector through the underlying conducting graphene network. The Mn(3)O(4) nanoparticles formed on RGO show a high specific capacity up to ∼900 mAh/g, near their theoretical capacity, with good rate capability and cycling stability, owing to the intimate interactions between the graphene substrates and the Mn(3)O(4) nanoparticles grown atop. The Mn(3)O(4)/RGO hybrid could be a promising candidate material for a high-capacity, low-cost, and environmentally friendly anode for lithium ion batteries. Our growth-on-graphene approach should offer a new technique for the design and synthesis of battery electrodes based on highly insulating materials.
The influence of rainfall, vegetation, elephants and people on fire frequency of miombo woodlands, Northern Mozambique

Miombo woodlands are ecologically and socially important in southern Africa, in which, anthropogenic dry season fires occur every year. This study explores the influence of several environmental factors on fire frequency of Niassa National Reserve in northern Mozambique. Our hypotheses are: 1) There are significant intra-annual differences in biomass according to fire frequency; 2) Fire frequency is influenced by the prevailing environmental conditions. We used a time series analysis and statistical f-test of MODIS-derived Enhanced Vegetation and Normalized Difference indices to address hypothesis 1. A stepwise logistic regression analysis was performed to tackle hypothesis 2. At the beginning of the fire season, biomass is higher in places with higher fire frequency. Land cover is the strongest predictor of fire frequency, but elephant density, annual rainfall and human corridors are also important.
A revisit of SO(6) dynamical symmetry in nuclear structure

Abstract According to an analysis based on the Fermion Dynamical Symmetry Model, nuclei previously regarded as SO(6)-like (e.g. 128 Xe and 196 Pt) are shown to be more akin to transitional nuclei between SO(7) and SO(6) symmetries.
On the Correlation Between Parity and Modular Polynomials

We consider the problem of bounding the correlation between parity and modular polynomials over ℤ q , for arbitrary odd integer q≥3. We prove exponentially small upper bounds for classes of polynomials with certain linear algebraic properties. As a corollary, we obtain exponential lower bounds on the size necessary to compute parity by depth-3 circuits with a MAJORITY gate at the top, MOD q gates at the middle level and AND gates at the input level, when the polynomials corresponding to the depth-2 MOD q ○AND subcircuits satisfy our conditions. Our methods also yield lower bounds for depth-3 MAJ○MOD q ○MOD 2 circuits (under certain restrictions) for computing parity. Our technique is based on a new general representation of the correlation using exponential sums, that allows to take advantage of the linear algebraic structure of the corresponding polynomials. Our results include Goldman’s result (Goldmann in Inf. Process. Lett. 53:321–327, 1995) on the correlation between parity and degree one polynomials as a special case. We also present a general expression for representing correlation, that can be used to yield our results as well as to derive the bounds of Cai, Green, and Thierauf (Math. Syst. Theory 29:245–258, 1996) for symmetric polynomials, using ideas of the Cai et al. (Math. Syst. Theory 29:245–258, 1996) proof. The classes of polynomials for which we obtain exponentially small upper bounds include polynomials of very large degree and with a very large number of terms, that previous techniques did not apply to.
Level Eulerian Posets

The notion of level posets is introduced. This class of infinite posets has the property that between every two adjacent ranks the same bipartite graph occurs. When the adjacency matrix is indecomposable, we determine the length of the longest interval one needs to check to verify Eulerianness. Furthermore, we show that every level Eulerian poset associated to an indecomposable matrix has even order. A condition for verifying shellability is introduced and is automated using the algebra of walks. Applying the Skolem---Mahler---Lech theorem, the ab-series of a level poset is shown to be a rational generating function in the non-commutative variables a and b. In the case the poset is also Eulerian, the analogous result holds for the cd-series. Using coalgebraic techniques a method is developed to recognize the cd-series matrix of a level Eulerian poset.
A natural partitioning scheme for parallel simulation of multibody systems

A parallel partitioning scheme based on physical-co-ordinate variables is presented to systematically eliminate system constraint forces and yield the equations of motion of multibody dynamics systems in terms of their independent coordinates. Key features of the present scheme include an explicit determination of the independent coordinates, a parallel construction of the null space matrix of the constraint Jacobian matrix, an easy incorporation of the previously developed two-stage staggered solution procedure and a Schur complement based parallel preconditioned conjugate gradient numerical algorithm.
Flavour stability of the chiral vacuum and scalar meson dynamics

Previous work relating the flavour variation of the chiral order parameters Fπ, ūu and S-wave scattering data, based on chiral sum rules and chiral perturbation theory at order p4, is extended to include O(p6) corrections. The finding of a significant decrease of these order parameters, particularly ūu, with the number of flavours increasing from NF = 2 to NF = 3 is confirmed, modulo an assumption on the convergence of the chiral expansion. The connection between scalar resonance physics and the phase structure of the chiral vacuum is also illustrated on the basis of the linear sigma-model. We allow for a very general symmetry breaking sector compatible with softness. The result depends strongly on the input scalar meson masses, in particular, on the presence, or not, of a light sigma.
Advice Lower Bounds for the Dense Model Theorem

We prove a lower bound on the amount of nonuniform advice needed by black-box reductions for the Dense Model Theorem of Green, Tao, and Ziegler, and of Reingold, Trevisan, Tulsiani, and Vadhan. The latter theorem roughly says that for every distribution D that is δ-dense in a distribution that is e′-indistinguishable from uniform, there exists a “dense model” for D, that is, a distribution that is δ-dense in the uniform distribution and is e-indistinguishable from D. This e-indistinguishability is with respect to an arbitrary small class of functions F. For the natural case where e′ ≥ Ω(eδ) and e ≥ δO(1), our lower bound implies that Ω(√(1/e) log(1/δ)·log|F|) advice bits are necessary for a certain type of reduction that establishes a stronger form of the Dense Model Theorem (and which encompasses all known proofs of the Dense Model Theorem in the literature). There is only a polynomial gap between our lower bound and the best upper bound for this case (due to Zhang), which is O((1/e2)log(1/δ)·log|F|). Our lower bound can be viewed as an analogue of list size lower bounds for list-decoding of error-correcting codes, but for “dense model decoding” instead.
“Black Swan Events” in Organic Synthesis

When a research area "goes viral", the event typically occurs in conjunction with a major change in "conventional wisdom". In retrospect, the literature often contains earlier hints that the original judgment was not correct. These antecedents are referred to as "Black Swan" events. The picture shows research on homogeneous gold catalysis "going viral".
Energy Transfer from an Individual Quantum Dot to a Carbon Nanotube

Precision measurements of resonant energy transfer from isolated quantum dots (QDs) to individual carbon nanotubes (CNTs) exhibit unique features due to the one-dimensional nature of CNTs. In particular, excitons can be created at varying distances from the QD at different locations along the CNT length. This leads to large variations in energy transfer length scales for different QDs and a novel saturation of the energy transfer efficiency at ∼96%, seemingly independent of CNT chirality.
Trade liberalization, product variety and growth in a small open economy: a quantitative assessment

Abstract We develop a numerical growth model that quantifies the welfare effects of trade liberalization. Additional intermediate input varieties provide the engine of growth and dramatically magnify the welfare gains from trade liberalization. In our central model, a 10% tariff cut leads to a 10.6% estimated gain in Hicksian EV. Systematic sensitivity analysis shows that there is virtually no chance of a welfare increase less than 3%, but a 6.6% chance of a welfare gain greater than 18%. We show that complementary reforms are crucial to fully realize the potential gains from the trade reform.
5'-alkyl-benzothiadiazides: a new subgroup of AMPA receptor modulators with improved affinity.

Abstract AMPA receptors form a major subdivision of the glutamate receptor family that mediates excitatory synaptic transmission in the brain. Currents through AMPA receptors can be up- or down-regulated by compounds that allosterically modulate receptor kinetics through binding sites distinct from that for glutamate. One of those modulators is the benzothiadiazide IDRA-21 which has been reported to enhance synaptic transmission and be effective in behavioral tests, but typically requires threshold concentrations of at least 100 μM to be active in vitro. In this study, new benzothiadiazides were developed with IDRA-21 as lead compound and examined for their potency in modulating AMPA receptor kinetics. A significant increase in drug affinity was obtained by alkyl substitution at the 5′-position of IDRA-21; substitutions at other positions of the benzothiadiazide core generally did not yield a further gain in affinity and in some cases abolished drug binding. The 5′-ethyl derivative exhibited an EC50 value in the order of 22 μM which represents about a 30-fold gain in affinity over that of IDRA-21. The EC50 value is comparable to that of cyclothiazide, the most potent benzothiadiazide drug, but the effects on AMPA receptors differed substantially between these two compounds in that the 5′-ethyl derivative of IDRA-21 greatly increased the binding affinity for receptor agonists whereas cyclothiazide is known to reduce agonist binding. The structure–activity relationships reported here thus offer to provide new insights how receptor kinetics is linked to particular aspects of receptor–drug interactions.
Optical Determination Of The Thermodynamic Phase Diagram Of A Metamagnet

Ferrous chloride is an antiferromagnet (AF) below its Neel temperature TN, but it may be driven into a saturated paramagmetic (SP) state by an external magnetic field applied along the c-axis. This AF-SP transition is first order below and continuous above a tricritical temperature Tc, a classic example of metamagnetism. With a pulsed dye laser, piezoelectric modulator, and a unique gated amplifier, we monitored the scattering of circularly polarized light by the mixed AF-SP phase below Tc. Above Tc the optical density of a sharp absorption line changes with the spin ordering; because the transition couples to spin fluctuations, the optical density maximizes in the SP phase. We have used these optical techniques to map the thermodynamic phase diagrams of FeC12 and FeC12 doped with cadmium, which to our knowledge is the first study of a randomly disordered critical system.
ROTATIONAL WIDTHS FOR USE IN THE TULLY-FISHER RELATION. I. LONG-SLIT SPECTROSCOPIC DATA

We present new long-slit Hα spectroscopy for 403 noninteracting spiral galaxies, obtained at the Palomar Observatory 5 m Hale telescope, which is used to derive well-sampled optical rotation curves. Because many of the galaxies show optical emission features that are significantly extended along the spectrograph slit, a technique was devised to separate and subtract the night sky lines from the galaxy emission. We exploit a functional fit to the rotation curve to identify its center of symmetry; this method minimizes the asymmetry in the final, folded rotation curve. We derive rotational widths using both velocity histograms and the Polyex model fit. The final rotational width is measured at a radius containing 83% of the total light as derived from I-band images. In addition to presenting the new data, we use a large sample of 742 galaxies for which both optical long-slit and radio H I line spectroscopy are available to investigate the relation between the H I content of the disks and the extent of their rotation curves. Our results show that the correlation between those quantities, which is well established in the case of H I–poor galaxies in clusters, is present also in H I–normal objects: for a given optical size, star formation can be traced farther out in the disks of galaxies with larger H I mass.
The interpretation of collision‐induced dissociation tandem mass spectra of peptides

The introduction of fast atom bombardment (FABJ ionization mass spectrometry (MSJ ( 1 ) in the early 1980s enabled mass spectrometrists to obtain molecular weights of many nonvolatile molecules, including p e p tides comprising 10-20 amino acids, and, by the mid-1980s. small proteins could be desorbed and their molecular weights measured (2-7). FAB (here used generically to include fast atom as well as ion bombardment of the sample dissolved in a liquid matrix such as glycerol), being a ”soft ionization” technique, produces little or no fragmentation of protonated peptide molecules. This characteristic is, certainly, desirable, because it allows for the unambiguous assignment of molecular weights, even in multicomponent mixtures. Nevertheless, fragmentation of a molecule, after ionization in the mass spectrometer, can be used to obtain structural information, often completely and uniquely, and for decades mass spectra of thousands of compounds have been acquired, interpreted, and cataloged. Peptides consisting of as few as several amino acids are nonvolatile and, often, thermally labile and cannot be introduced into the mass spectrometer in the gas phase without prior derivatization. Derivatized peptides have been successfully fragmented, primarily using electron impact (El) ionization, and their amino acid sequence determined (8-1 3). sometimes with the assistance of computer programs ( 1 4). Complex mixtures of protein enzyme digests, often followed by partial acid hydrolysis, were derivatized and introduced into the mass spectrometer after fractionation with a gas chromatograph (GC). The El spectra were used to obtain amino acid sequences for the peptides, which were subsequently combined to arrive at the sequence of the protein. Peptide fragments, which sometimes are produced during FAB ionization, can be correlated to the peptide amino acid sequence ( 15-20). The abundance of such fragment ions, however, is quite low compared with the ions due to the protonated molecule. In addition, in order to obtain reasonably abundant fragment ions, a fairly concentrated sample is required, and even then large peptides (e.9.. longer than 10 amino acids) do not fragment efficiently. Also, at lower mass (e.g., below m/z 500). fragment ions are usually difficult to identify, due to the FAB matrix background, and, of course, in mixtures more than one peptide usually fragments, thereby increasing the difficulty of fragment ion assignments to particular precursor ions. The advent of tandem mass spectrometry (MS/MS) (2 1-23) made it possible to analyze complex peptide mixtures (24-34) without the need to separate the individual components, because a mass window narrow enough to exclude all but one of the mixture components can be specified
Biosynthetic Methods for the Production of Advanced Protein‐Based Materials

The biosynthesis of protein‐based polymers offers unparalleled opportunities for the production of polymeric materials in which structure and function can be precisely specified. In addition to the continued progress in the design and use of polypeptidic materials with sequences based on the silks, collagens, and elastins, new opportunities for controlling polymer properties are possible in biosynthetically derived polypeptides that capture the properties of other natural proteins or that are designed de novo. Advances in the integration of biosynthetic and chemical methods also offer exciting prospects in the design of new polymeric materials. These innovations have stimulated both the improved understanding and expanded application of biosynthetically derived protein‐based polymers.
Angular momentum and the formation of stars and black holes

The formation of compact objects such as stars and black holes is strongly constrained by the requirement that nearly all of the initial angular momentum of the diffuse material from which they form must be removed or redistributed during the formation process. The mechanisms that may be involved and their implications are discussed for (1) low-mass stars, most of which probably form in binary or multiple systems; (2) massive stars, which typically form in clusters and (3) supermassive black holes that form in galactic nuclei. It is suggested that in all cases, gravitational interactions with other stars or mass concentrations in a forming system play an important role in redistributing angular momentum and thereby enabling the formation of a compact object. If this is true, the formation of stars and black holes must be a more complex, dynamic and chaotic process than in standard models. The gravitational interactions that redistribute angular momentum tend to couple the mass of a forming object to the mass of the system, and this may have important implications for mass ratios in binaries, the upper stellar IMF in clusters, and the masses of supermassive black holes in galaxies.
GALAXIES CORRELATING WITH ULTRA-HIGH ENERGY COSMIC RAYS

The Pierre Auger Observatory reported that 20 of the 27 highest energy cosmic rays have arrival directions within 3.{sup 0}2 of a nearby galaxy in the Veron-Cetty and Veron (VCV) Catalog of Quasars and Active Galactic Nuclei (12th ed.), with a 1% probability that this would be due to chance if the cosmic ray directions were isotropic. In this paper, we examine the correlated galaxies to gain insight into the possible ultra-high energy cosmic ray (UHECR) sources. We find that 14 of the 21 correlated VCV galaxies are active galactic nuclei (AGNs) and we determine their bolometric luminosities. The remaining seven are primarily star-forming galaxies. The bolometric luminosities of the correlated AGNs are all greater than 5 x 10{sup 42} erg s{sup -1}. This may explain the absence of UHECRs from the Virgo region in spite of the large number of VCV galaxies in Virgo, since most of the VCV galaxies in the Virgo region are low-luminosity AGNs. Interestingly, the bolometric luminosities of most of the AGNs are significantly lower than that required to satisfy the minimum condition for UHECR acceleration in a continuous jet. If a UHECR-AGN correlation is substantiated with further statistics, our results lend support to themore » recently proposed 'giant AGN flare' mechanism for UHECR acceleration.« less
An introduction to the Enterprise Risk Scorecard

Purpose – The purpose of this paper is to introduce the concept of an Enterprise Risk Scorecard.Design/methodology/approach – With the accelerating growth in global risk levels leading to an intense current demand for risk management solutions, an analysis was conducted on whether a scorecard framework could be applied to risk measurement. This analysis included a survey of Kaplan and Norton's voluminous and seminal writings on the Balanced Scorecard, in which, surprisingly, relatively little on the measurement of risk was found.Findings – The findings suggest that a scorecard framework could be an effective risk measurement, management and communication tool. For both design and organizational reasons it is recommended that risk scorecards be separate from performance scorecards.Research limitations/implications – Utilizing two scorecards – one for performance and a separate one for risk – could provide strategy‐focused organizations with a more comprehensive diagnostic control system. The research impli...
Photometric properties of lunar terrains derived from Hapke's equation

The fitting of Hapke's (1986) photometric parameters to the lunar disk-integrated visual lightcurve, as well as to disk-resolved data of Shorthill et al. (1969) for dark, average, and bright lunar terrains, leads to computational results from the disk-integrated results for the nearside geometric albedo and phase integral that are consistent with those of earlier investigations. The angular width of the opposition surge, which is noted to be greatest in dark terrains, can be accounted for in terms of modest differences in regolith particle-size distributions that could be associated with regolith maturation.
Real-time navigation of independent agents using adaptive roadmaps

We present a novel algorithm for navigating a large number of independent agents in complex and dynamic environments. We compute adaptive roadmaps to perform global path planning for each agent simultaneously. We take into account dynamic obstacles and inter-agents interaction forces to continuously update the roadmap by using a physically-based agent dynamics simulator. We also introduce the notion of 'link bands' for resolving collisions among multiple agents. We present efficient techniques to compute the guiding path forces and perform lazy updates to the roadmap. In practice, our algorithm can perform real-time navigation of hundreds and thousands of human agents in indoor and outdoor scenes.
On a theorem of Hazrat and Hoobler

We use cycle complexes with coefficients in an Azumaya algebr a, as developed by Kahn and Levine, to compare the G-theory of an Azumaya algebra to the Gtheory of the base scheme. We obtain a sharper version of a theorem of Hazrat and Hoobler in certain cases.
Shellable Complexes and Topology of Diagonal Arrangements

We prove that if a simplicial complex Δ is shellable, then the intersection lattice L Δ for the corresponding diagonal arrangement $\mathcal{A}_{\Delta }$is homotopy equivalent to a wedge of spheres. Furthermore, we describe precisely the spheres in the wedge, based on the data of shelling. Also, we give some examples of diagonal arrangements $\mathcal{A}$where the complement $\mathcal{M}_{\mathcal{A}}$is K(π,1), coming from rank-3 matroids.
Is the proposed East African Monetary Union an optimal currency area? a structural vector autoregression analysis

Summary This paper empirically assesses the suitability of the East African (EA) countries for a regional monetary union by testing for symmetry of the underlying structural shocks. The results indicate that supply and demand shocks are generally asymmetric, which does not lend strong support for forming a currency union in the EA region at the moment. However, the speed and magnitude of adjustment to shocks is similar across the countries. Therefore, further integration of the economies might lead to more favorable conditions for a monetary union. Although evidence in favor of linking an EA currency to an external anchor is weak, such support seems to favor the Euro.
Feedstock Blending Studies With Laboratory Indirectly Heated Gasifiers

To support the further development of indirectly heated gasifiers intended to provide fuels for advanced gas turbines, several indirectly heated laboratory gasifiers were constructed. During many comparative tests, advantages and problems with each system were observed. The most useful systems make use of laboratory tube furnaces in conjunction with temperature, time and pressure or volume yield measuring systems and a gas chromatograph with a thermal conductivity detector. In this paper, high temperature pyrolysis results obtained with the latest system are presented. Contrasting feedstocks suitable for commercial systems separately or in blends are used. Yield versus time measurements are used to determine relevant rate constants and outputs. Since the rate constants are mainly reflective of heat transfer effects, cylindrical dowel sticks of varying radii were volatilized. The data set leads to an analytic heat transfer model that considers the hemicellulose, cellulose, and lignin components of the dowels. Also developed from the dowel experiments is an approximate procedure for estimating the proportionate releases of CO, CO{sub 2}, CH{sub 4}, and H{sub 2} for any type of biomass whose component proportions are known.
Leader Ethical Decision-Making in Organizations: Strategies for Sensemaking.

Organizational leaders face environmental challenges and pressures that put them under ethical risk. Navigating this ethical risk is demanding given the dynamics of contemporary organizations. Traditional models of ethical decision-making (EDM) are an inadequate framework for understanding how leaders respond to ethical dilemmas under conditions of uncertainty and equivocality. Sensemaking models more accurately illustrate leader EDM and account for individual, social, and environmental constraints. Using the sensemaking approach as a foundation, previous EDM models are revised and extended to comprise a conceptual model of leader EDM. Moreover, the underlying factors in the model are highlighted—constraints and strategies. Four trainable, compensatory strategies (emotion regulation, self-reflection, forecasting, and information integration) are proposed and described that aid leaders in navigating ethical dilemmas in organizations. Empirical examinations demonstrate that tactical application of the strategies may aid leaders in making sense of complex and ambiguous ethical dilemmas and promote ethical behavior. Compensatory tactics such as these should be central to organizational ethics initiatives at the leader level.
The importance of randomized clinical trials and evidence‐based medicine: A clinician's perspective

Clinical evaluation of therapies for patient care has evolved during the twentieth century from a variety of scientific methods. As a result of medical, political, and economic changes that occurred in the 1990s, randomized clinical trials and evidence-based methods are presently in the forefront of the physician's thinking in the decision-making process for therapeutic interventions. A new standard of patient care has emerged during this process. This report provides a clinician's viewpoint of the importance and interpretation of evidence-based methods and suggests a strategy when such evidence does not exist.
Direct Asymmetric Michael Addition to Nitroalkenes: Vinylogous Nucleophilicity under Dinuclear Zinc Catalysis

Under dinuclear catalysis, the direct conjugate addition of 2(5H)-furanone to nitroalkenes involves the γ-position of the nucleophile. The synthetically versatile Michael adducts are prepared in good yields, with high levels of diastereo- and enantioselectivity. A model is presented to rationalize the observed stereoselectivity.
Fourier–Dedekind sums and an extension of Rademacher reciprocity

Fourier–Dedekind sums are a generalization of Dedekind sums—important number-theoretical objects that arise in many areas of mathematics, including lattice point enumeration, signature defects of manifolds, and pseudorandom number generators. A remarkable feature of Fourier–Dedekind sums is that they satisfy a reciprocity law called Rademacher reciprocity. In this paper, we study several aspects of Fourier–Dedekind sums: properties of general Fourier–Dedekind sums, extensions of the reciprocity law, average behavior of Fourier–Dedekind sums, and finally, extrema of 2-dimensional Fourier–Dedekind sums. On properties of general Fourier–Dedekind sums, we show that a general Fourier–Dedekind sum is simultaneously a convolution of simpler Fourier–Dedekind sums, and, in a precise sense, almost a linear combination of these with integer coefficients. We show that Fourier–Dedekind sums can be extended naturally to a group under convolution. We introduce “Reduced Fourier–Dedekind sums,” which encapsulate the complexity of a Fourier–Dedekind sum, describe these in terms of generating functions, and give a geometric interpretation. Next, by finding interrelations among Fourier–Dedekind sums, we extend the range on which Rademacher Reciprocity Theorem holds. We study the average behavior of Fourier–Dedekind sums, showing that the average behavior of a Fourier–Dedekind sum is described concisely by a lower-dimensional, simpler Fourier–Dedekind sum. Finally, we focus our study on 2-dimensional Fourier–Dedekind sums. We find tight upper and lower bounds on these for a fixed $$t$$ , estimates on the argmax and argmin, and bounds on the sum of their “reciprocals.”
Protecting data privacy through hard-to-reverse negative databases

A set DB of data elements can be represented in terms of its complement set, known as a negative database. That is, all of the elements not in DB are represented, and DB itself is not explicitly stored. This method of representing data has certain properties that are relevant for privacy enhancing applications. The paper reviews the negative database (NDB) representation scheme for storing a negative image compactly, and proposes using a collection of NDBs to represent a single DB, that is, one NDB is assigned for each record in DB. This method has the advantage of producing negative databases that are hard to reverse in practice, i.e., from which it is hard to obtain DB. This result is obtained by adapting a technique for generating hard-to-solve 3-SAT formulas. Finally we suggest potential avenues of application.
Reductive glutamine metabolism is a function of the α-ketoglutarate to citrate ratio in cells

Reductively metabolized glutamine is a major cellular carbon source for fatty acid synthesis during hypoxia or when mitochondrial respiration is impaired. Yet, a mechanistic understanding of what determines reductive metabolism is missing. Here we identify several cellular conditions where the α-ketoglutarate/citrate ratio is changed due to an altered acetyl-CoA to citrate conversion, and demonstrate that reductive glutamine metabolism is initiated in response to perturbations that result in an increase in the α-ketoglutarate/citrate ratio. Thus, targeting reductive glutamine conversion for a therapeutic benefit might require distinct modulations of metabolite concentrations rather than targeting the upstream signalling, which only indirectly affects the process.
Reductions in parachute drag due to forebody wake effects

An experiment was conducted to evaluate approximate analytical methods for predicting the reduction in parachute drag due to forebody wake effects. The drag of a 20/sup 0/ conical ribbon parachute was measured at several axial stations behind an ogive-cylinder forebody with and without fins. The same parachute was tested in undisturbed flow (where wake effects were negligible) so that the effects of suspension line length on parachute drag could be separated from the drag losses caused by the turbulent wake. Total head pressure surveys were made across the forebody wake and integrated across the canopy skirt area to determine the effective dynamic pressure acting on the parachute. Experimental results confirmed the validity of the underlying physical model of the parachute/wake interaction: the ratio of parachute drag behind a forebody divided by wake-free parachute drag is equal to the ratio of effective dynamic pressure acting on the parachute divided by freestream dynamic pressure.
Graphical methods used in the numerical solution of Jeffery-Hamel flow at fixed flow rates

Abstract A basic problem in the area of Fluid Dynamics is the solution of the Navier-Stokes equations describing the radial flow of viscous incompressible fluid between non-parallel plane walls. Since the known solutions involve transcendental equations containing elliptic functions, there are no explicit equations or methods available for determining the shape of the velocity profile for specified boundary conditions that do not require an iterative or graphical technique. The purpose of this paper is to describe the computer generated graphical solutions which allow for an easy determination of the velocity profile for fixed flow conditions. This paper will describe the step by step process of extending the solution of the problem by working back and forth between the graphical representation of the equations and the numerical solution.
Spectral filtering for ultra‐fast mode‐locking in the normal dispersive regime

A theoretical model is developed which characterizes the physical process responsible for generating ultra-short, high-energy, mode-locked pulses in a normal GVD laser cavity with spectral filtering. Two physical parameters are critical to achieving optimal performance: the ratio of the filter bandwidth to the gain bandwidth and the placement of the output coupler in the laser cavity. The spectral filtering allows for the high-energy of typical normal GVD laser cavities to be maintained while the pulse intensity doubles and the FWHM reduces by an order of magnitude. This phenomenon is generic and ubiquitous to normal GVD mode-locking. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
Behavior of fully stressed design of structures and its relationshipto minimum-weight design.

The iterative method of analysis and fully stressed redesign does not always converge to a minimum-weight design. Using the Kuhn-Tucker optimality condition of nonlinear programing, the necessary condition for the equivalence of the two methods of design is found and a computationally practical method for verification of the optimality of fully stressed design is obtained. Where the fully stressed design is not optimum a method is suggested for determination of the optimum which reduces the dimensionality of the problem by dividing the design variables into free and fully stressed ones. Then, the optimization is decentralized into an optimal search on free design variables and fully stressed design of the rest of the variables.
Strongly Coupled Condensate of High Density Matter

Arguments are summarized, that neutral matter made of helium, carbon, etc., should form a quantum liquid at the above-atomic but below-nuclear densities for which the charged spin-0 nuclei can condense. The resulting substance has distinctive features, such as a mass gap in the bosonic sector and a gap-less spectrum of quasifermions, which determine its thermodynamic properties. I discuss an effective field theory description of this substance, and as an example, consider its application to calculation of a static potential between heavy charged impurities. The potential exhibits a long-range oscillatory behavior in which both the fermionic and bosonic low-energy degree of freedom contribute. Observational consequences of the condensate for cooling of helium-core white dwarf stars are briefly discussed.
Oligosaccharide synthesis by enzymatic transglycosylation

Agricultural Research Service, United States Department of Agriculture, Northern Regional Research Center, 1815 N. University St., Peoria, IL 61604, U.S.A. 2 Biochemical and Food Process Engineering, Agricultural Engineering Department, Purdue University, West Lafayette, IN 47907, U.S.A.
Synthesis of bisbicyclo[1.1.1]pentyldiazene. The smallest bridgehead diazene.

Bisbicyclo[1.1.1]pentyldiazene, the smallest bicyclic azo compound, has been synthesized from the precursor [1.1.1]propellane via synthesis of N,N‘-bis(bicyclo[1.1.1]pentyl)sulfamide and azoxybicyclo[1.1.1]pentane. The UV absorption of this diazene at 382 nm indicates that the compound is the trans isomer. Conversion to the cis isomer by irradiation was not possible because of attainment of a photostationary state. However, on the basis of the photochemical studies, the absorption of the cis-[1.1.1] isomer is estimated to be 384 nm.
DARK MATTER BURNERS

We show that a star orbiting close enough to an adiabatically grown supermassive black hole (SMBH) can capture weakly interacting massive particles (WIMPs) at an extremely high rate. The stellar luminosity due to annihilation of captured WIMPs in the stellar core may be comparable to or even exceed the luminosity of the star due to thermonuclear burning. The model thus predicts the existence of unusual stars, essentially WIMP burners, in the vicinity of a SMBH. We find that the most efficient WIMP burners are stars with degenerate electron cores, e.g. white dwarfs (WDs); such WDs may have a very high surface temperature. If found, such stars would provide evidence for the existence of particle dark matter and can possibly be used to establish its density profile. On the other hand, the lack of such unusual stars may provide constraints on the WIMP density near the SMBH, as well as the WIMP-nucleus scattering and pair annihilation cross-sections.
Periodic subsystem density-functional theory

By partitioning the electron density into subsystem contributions, the Frozen Density Embedding (FDE) formulation of subsystem Density Functional Theory (DFT) has recently emerged as a powerful tool for reducing the computational scaling of Kohn–Sham DFT. To date, however, FDE has been employed to molecular systems only. Periodic systems, such as metals, semiconductors, and other crystalline solids have been outside the applicability of FDE, mostly because of the lack of a periodic FDE implementation. To fill this gap, in this work we aim at extending FDE to treat subsystems of molecular and periodic character. This goal is achieved by a dual approach. On one side, the development of a theoretical framework for periodic subsystem DFT. On the other, the realization of the method into a parallel computer code. We find that periodic FDE is capable of reproducing total electron densities and (to a lesser extent) also interaction energies of molecular systems weakly interacting with metallic surfaces. In the pilot calculations considered, we find that FDE fails in those cases where there is appreciable density overlap between the subsystems. Conversely, we find FDE to be in semiquantitative agreement with Kohn–Sham DFT when the inter-subsystem density overlap is low. We also conclude that to make FDE a suitable method for describing molecular adsorption at surfaces, kinetic energy density functionals that go beyond the GGA level must be employed.
Madden-Julian Oscillation in the tropical stratosphere

[1] Links are sought between Madden-Julian Oscillation (MJO)-related variations in the troposphere and stratospheric winds, temperature, and ozone. Tropospheric variations of equatorial MJO-filtered 200 hPa zonal winds define indices of MJO activity for two equatorial regions in the Indian and Western Pacific oceans. These indices are used to calculate composite means of MJO filtered winds, temperature, and ozone mixing ratio for eight height levels from the upper troposphere well into the stratosphere. Strong evidence is presented for significant and coherent MJO departures throughout the lower stratosphere. At 100 hPa, these departures show easterlies in the equatorial regions of the compositing centers and nearly symmetric anticyclonic centers at 25° poleward of those centers, which are associated with significant negative departures in both temperature and ozone mixing ratio. Near 40°N MJO departures of meridional velocity, temperature, and ozone mixing ratio generally tilt westward with height. The most important aspects of these features propagate eastward at a rate of about 5 m/s in the Eastern Hemisphere and several times faster in the Western Hemisphere.
The SIM PlanetQuest science program

SIM PlanetQuest (hereafter, just SIM) is a NASA mission to measure the angular positions of stars with unprecedented accuracy. We outline the main astrophysical science programs planned for SIM, and related opportunities for community participation. We focus especially on SIM's ability to detect exoplanets as small as the Earth around nearby stars. The planned synergy between SIM and other planet-finding missions including Kepler and GAIA, and planet-characterizing missions including the James Webb Space Telescope (JWST), Terrestrial Planet Finder--Coronagraph (TPF-C), and Terrestrial Planet Finder--Interferometer (TPF-I), is a key element in NASA's Navigator Program to find Earth-like planets, determine their habitability, and search for signs of life in the universe. SIM's technology development is now complete and the project is proceeding towards a launch in the next decade.
Antimicrobial compounds from Ceanothus americanus against oral pathogens

During the search for antimicrobial compounds from higher plant sources, a methanol extract of Ceanothus americanus demonstrated antimicrobial activity against selected oral pathogens. Through further bioassay-guided fractionation and purification, three triterpenes (ceanothic acid, 27-hydroxy ceanothic acid and ceanothetric acid) and two flavonoids (maesopsin and maesopsin-6-O-glucoside) were identified. Among these, ceanothetric acid and maesopsin-6-O-glucoside were new compounds. Ceanothic acid and ceanothetric acid demonstrated growth inhibitory effect against Streptococcus mutans, Actinomyces viscosus, Porphyromonas gingivalis, and Prevotella intermedia with MICs ranging from 42 to 625 micrograms ml-1. Maesopsin, its glucoside, and 27-hydroxy ceanothic acid, were inactive below the concentration of 500 micrograms ml-1.
“Family-Friendly” Fringe Benefits and the Gender Wage Gap

Evidence suggests a large portion of the gender wage gap is explained by gender occupational segregation. A common hypothesis is that gender differences in preferences or abilities explain this segregation; women may prefer jobs that provide more “family-friendly” fringe benefits. Much of the research provides no direct evidence on gender differences in access to fringe benefits, nor how provision affects wages. Using data from the National Longitudinal Survey of Youth 1979, we find that women are more likely to receive family-friendly benefits, but not other types of fringe benefits. We find no evidence that the differences in fringe benefits explain the gender wage gap.
Highly stereoselective synthesis of exocyclic alkenes via cyclialkylation

Abstract Treatment of stereodefined ω-halo-2-iodoalkene derivatives (1), prepared via stereoselective addition reactions of alkynes, with either n -BuLi (1 equiv) or t -BuLi (2 equiv) can produce exocyclic alkenes whose isomeric purity is essentially 100%.
Study of nondiagonal parton distribution models

Abstract In this paper we examine predictions from different models of nondiagonal parton distributions. This will be achieved by examining whether certain predictions of relationships between diagonal and nondiagonal parton distributions also hold after having evolved the different distributions.
Information Between Quantum Systems via POVMs

The concepts of conditional entropy and information between subsystems of a composite quantum system are generalized to include arbitrary indirect measurements (POVMs). Some properties of those quantities differ from those of their classical counterparts; certain equalities and inequalities of classical information theory may be violated.
Multifluid, Magnetohydrodynamic Shock Waves with Grain Dynamics. II. Dust and the Critical Speed for C Shocks

This is the second in a series of papers on the effects of dust on multifluid, magnetohydrodynamic shock waves in weakly ionized molecular gas. We investigate the influence of dust on the critical shock speed, vcrit, above which C shocks cease to exist. Chernoff showed that vcrit cannot exceed the grain magnetosound speed, Vgms, if dust grains are dynamically well coupled to the magnetic field. Since Vgms 5 km s-1 in a dense cloud or core, the potential implications for models of shock emission are profound. We present numerical simulations of steady shocks where the grains may be well or poorly coupled to the field. We use a time-dependent, multifluid MHD code that models the plasma as a system of interacting fluids: neutral particles, ions, electrons, and various "dust fluids" comprised of grains with different sizes and charges. Our simulations include grain inertia and grain charge fluctuations, but to highlight the essential physics we assume adiabatic flow and single-size grains and neglect the effects of chemistry. We show that the existence of a phase speed v does not necessarily mean that C shocks will form for all shock speeds vs less than v. When the grains are weakly coupled to the field, steady, adiabatic shocks resemble shocks with no dust: the transition to J-type flow occurs at vcrit ≈ 2.76VnA, where VnA is the neutral Alfven speed, and steady shocks with vs > 2.76VnA are J shocks with magnetic precursors in the ion-electron fluid. When the grains are strongly coupled to the field, vcrit = min (2.76VnA,Vgms). Shocks with vcrit Vgms have no magnetic precursor in any fluid. We present time-dependent calculations to study the formation of steady, multifluid shocks. The dynamics differ qualitatively, depending on whether or not the grains and field are well coupled.
Production and characterization of carbamazepine nanocrystals by electrospraying for continuous pharmaceutical manufacturing

In this paper, an electrospray technique followed by annealing at high temperatures was developed to produce nanocrystals of carbamazepine (CBZ), a poorly water-soluble drug, for continuous pharmaceutical manufacturing process. Electrospraying solutions of CBZ in methanol obeys the expected scaling law of current, which is I ∼ Q(1/2) (I, electrical current; Q, flow rate), for liquids with sufficiently high conductivity and viscosity. Lower flow rates during electrospraying were preferred to produce smaller diameters of monodisperse, dense CBZ nanoparticles. CBZ nanoparticles were predominantly amorphous immediately after electrospraying. Crystallization of CBZ nanoparticles was accelerated by annealing at high temperatures. CBZ nanocrystals with the most stable polymorph, form III, were obtained by annealing at 90°C, which is above the transition temperature, 78°C, for the enantiotropic CBZ form III and form I. The solubility and dissolution rates of CBZ nanocrystals increased significantly as compared with those of CBZ bulk particles. Therefore, electrospray technology has the potential to produce pharmaceutical dosage forms with enhanced bioavailability and can readily be integrated in a continuous pharmaceutical manufacturing process.