cssi/SciSciGPT-SciSciNet huggingface dataset:
Cytochrome c-mediated formation of S-nitrosothiol in cells

S-nitrosothiols are products of nitric oxide (NO) metabolism that have been implicated in a plethora of signalling processes. However, mechanisms of S-nitrosothiol formation in biological systems are uncertain, and no efficient protein-mediated process has been identified. Recently, we observed that ferric cytochrome c can promote S-nitrosoglutathione formation from NO and glutathione by acting as an electron acceptor under anaerobic conditions. In the present study, we show that this mechanism is also robust under oxygenated conditions, that cytochrome c can promote protein S-nitrosation via a transnitrosation reaction and that cell lysate depleted of cytochrome c exhibits a lower capacity to synthesize S-nitrosothiols. Importantly, we also demonstrate that this mechanism is functional in living cells. Lower S-nitrosothiol synthesis activity, from donor and nitric oxide synthase-generated NO, was found in cytochrome c-deficient mouse embryonic cells as compared with wild-type controls. Taken together, these data point to cytochrome c as a biological mediator of protein S-nitrosation in cells. This is the most efficient and concerted mechanism of S-nitrosothiol formation reported so far.
Landscape analysis and the search for geomorphic unity

Geomorphology has been an integral part of geological science since the inception of the Geological Society of America, even though different investigative goals have existed continuously in the discipline. The dichotomy of purpose began with the vastly different perception of landscape analysis embraced by William Morris Davis and G. K. Gilbert. Historical and physical geomorphic studies have always been conducted simultaneously, but one of these research activities has dominated the field at any given time. During the first half of this century, most geomorphic work was devoted to the interpretation of long-term, evolutionary history of regional landscapes. In the past four decades, however, research has concentrated on the study of geomorphic processes. This revised direction placed greater emphasis on the physical component of geomorphology and provided a more complete understanding of the time factor in landscape analysis. Historical geomorphology is now less concerned with theories of cyclic-time landscape development and more involved in determining the time and sequence of shorter episodes of geomorphic disequilibrium caused by tectonism and/or climate change. The tenor of future research in surficial geology will require input from both physical and historical geomorphology, and therefore a greater unity of purpose among geomorphologists can be expected. Geomorphologists will have the opportunity to provide geologists and engineers with useful data about major scientific and technical problems related to plate-tectonic theory, interpretation of the stratigraphic record, and prediction of landform stability for environmental planning.
Single board op-amp beam position monitors electronics

A new approach has been developed for beam position monitors (BPM) in the new 600 keV beamline. A single four layer printed circuit board, attached with short (0.3 m) cables to the electrodes, processes the raw signals and outputs voltages proportional to the beam intensity, horizontal and vertical position, and quadrapole moment. Newly-available high-speed operational amplifiers are used exclusively instead of more conventional RF components. The RF input frequency can be as high as 36 MHz, and the IF frequency is 100 kHz. The output signals from each monitor will be digitized by the VME-based control system which will provide operator displays and use the information as feedback in automatic loops controlling the beam position, envelope, and dispersion. The signal processing at each BPM location eliminates the need for expensive multiplexing and routing of signals to a central processing location. The cylindrical electrode is split into four equal segments allowing both horizontal and vertical information to be obtained at each location thus minimizing the required beamline insertion length. >
Electric impedance microflow cytometry for characterization of cell disease states

The electrical properties of biological cells have connections to their pathological states. Here we present an electric impedance microflow cytometry (EIMC) platform for the characterization of disease states of single cells. This platform entails a microfluidic device for a label-free and non-invasive cell-counting assay through electric impedance sensing. We identified a dimensionless offset parameter δ obtained as a linear combination of a normalized phase shift and a normalized magnitude shift in electric impedance to differentiate cells on the basis of their pathological states. This paper discusses a representative case study on red blood cells (RBCs) invaded by the malaria parasite Plasmodium falciparum. Invasion by P. falciparum induces physical and biochemical changes on the host cells throughout a 48-h multi-stage life cycle within the RBC. As a consequence, it also induces progressive changes in electrical properties of the host cells. We demonstrate that the EIMC system in combination with data analysis involving the new offset parameter allows differentiation of P. falciparum infected RBCs from uninfected RBCs as well as among different P. falciparum intraerythrocytic asexual stages including the ring stage. The representative results provided here also point to the potential of the proposed experimental and analysis platform as a valuable tool for non-invasive diagnostics of a wide variety of disease states and for cell separation.
First Detection of Millimeter/Submillimeter Extragalactic H2O Maser Emission

We report the first detection of an extragalactic millimeter wavelength H2O maser at 183 GHz toward NGC 3079 using the Submillimeter Array (SMA) and a tentative submillimeter wave detection of the 439 GHz maser toward the same source using the James Clerk Maxwell Telescope (JCMT). These H2O transitions are known to exhibit maser emission in star-forming regions and evolved stars. NGC 3079 is a well-studied nuclear H2O maser source at 22 GHz with a time-variable peak flux density in the range 3-12 Jy. The 183 GHz H2O maser emission, with a peak flux density of ~0.5 Jy (7 σ detection), also originates from the nuclear region of NGC 3079 and is spatially coincident with the dust continuum peak at 193 GHz (53 mJy integrated). Peak emission at both 183 and 439 GHz occurs in the same range of velocity as that covered by the 22 GHz spectrum. We estimate the gas-to-dust ratio of the nucleus of NGC 3079 to be ≈150, comparable to the Galactic value of 160. Discovery of maser emission in an active galactic nucleus beyond the long-known 22 GHz transition opens the possibility of future position-resolved radiative transfer modeling of accretion disks and outflows <1 pc from massive black holes.
Separating the Wheat from the Chaff: Icelandic and Irish Policy Responses to the Banking Crisis

When the tales of the Icelandic and Irish crises are told, they are framed as if one country did everything right to exit recession. In this paper I assess their recovery policies and find that the truth lies somewhere in the middle. By allowing its banking system to suffer substantial losses, Iceland shielded its citizens from the costly debt overhand apparent in Ireland. Ireland’s commitment to open capital markets and price deflation has allowed trade flows to remain robust, and relative prices to realign to signal sustainable production plans to entrepreneurs. These lessons provide a roadmap for other countries entering similar crises in the future.
Knowledge-based nonuniform crossover

One-point, two-point and k-point crossover can be viewed as special cases of uniform crossover, where genetic material is chosen each locus of either parent with equal probability (G. Syswerda, 1989). The paper generalizes uniform crossover to "non-uniform crossover" using "mask" vectors whose elements are real numbers /spl isin/[0, 1], representing problem-specific knowledge that improves performance by biasing the selection of alleles from either parent. This knowledge based non-uniform crossover (KNUX) is applied to two NP optimization problems: graph partitioning and soft-decision decoding of linear block codes (H.S. Maini, 1993). Simulation results show orders of magnitude improvement of this operator over two-point and uniform crossover. An appropriate schema theorem is also developed. >
LRS2: the new facility low resolution integral field spectrograph for the Hobby-Eberly telescope

The second generation Low Resolution Spectrograph (LRS2) is a new facility instrument for the Hobby-Eberly Telescope (HET). Based on the design of the Visible Integral-field Replicable Unit Spectrograph (VIRUS), which is the new flagship instrument for carrying out the HET Dark Energy Experiment (HETDEX), LRS2 provides integral field spectroscopy for a seeing-limited field of 12" x 6". For LRS2, the replicable design of VIRUS has been leveraged to gain broad wavelength coverage from 370 nm to 1.0 μm, spread between two fiber-fed dual- channel spectrographs, each of which can operate as an independent instrument. The blue spectrograph, LRS2-B, covers 370 λ (nm) ≤ 470 and 460 ≤ λ (nm) ≤ 700 at fixed resolving powers of R = λ/δλ ≈ 1900 and 1100, respectively, while the red spectrograph, LRS2-R, covers 650 ≤ λ (nm) ≤ 842 and 818 ≤ λ (nm) ≤ 1050 with both of its channels having R ≈ 1800. In this paper, we present a detailed description of the instrument’s design in which we focus on the departures from the basic VIRUS framework. The primary modifications include the fore-optics that are used to feed the fiber integral field units at unity fill-factor, the cameras’ correcting optics and detectors, and the volume phase holographic grisms. We also present a model of the instrument’s sensitivity and a description of specific science cases that have driven the design of LRS2, including systematically studying the spatially resolved properties of extended Lyα blobs at 2 z < 3. LRS2 will provide a powerful spectroscopic follow-up platform for large surveys such as HETDEX.
Robotic pets in the lives of preschool children

This study examined preschool children’s reasoning about and behavioral interactions with one of the most advanced robotic pets currently on the retail market, Sony’s robotic dog AIBO. Eighty children, equally divided between two age groups, 34–50 months and 58–74 months, participated in individual sessions with two artifacts: AIBO and a stuffed dog. Evaluation and justification results showed similarities in children’s reasoning across artifacts. In contrast, children engaged more often in apprehensive behavior and attempts at reciprocity with AIBO, and more often mistreated the stuffed dog and endowed it with animation. Discussion focuses on how robotic pets, as representative of an emerging technological genre, may be (a) blurring foundational ontological categories, and (b) impacting children’s social and moral development.
An upper bound for the number of independent sets in regular graphs

Write I(G) for the set of independent sets of a graph G and i(G) for |I(G)|. It has been conjectured (by Alon and Kahn) that for an N-vertex, d-regular graph G, i(G)@?(2^d^+^1-1)^N^/^2^d. If true, this bound would be tight, being achieved by the disjoint union of N/2d copies of K"d","d. Kahn established the bound for bipartite G, and later gave an argument that established i(G)@?2^N^2^(^1^+^2^d^) for G not necessarily bipartite. In this note, we improve this to i(G)@?2^N^2^(^1^+^1^+^o^(^1^)^d^) where o(1)->0 as d->~, which matches the conjectured upper bound in the first two terms of the exponent. We obtain this bound as a corollary of a new upper bound on the independent set polynomial P(@l,G)[email protected]?"I"@?"I"("G")@l^|^I^| of an N-vertex, d-regular graph G, namely P(@l,G)@?([email protected])^N^22^N^(^1^+^o^(^1^)^)^2^d valid for all @l>0. This also allows us to improve the bounds obtained recently by Carroll, Galvin and Tetali on the number of independent sets of a fixed size in a regular graph.
Sulfate Metabolism in Mycobacteria

Pathogenic bacteria have developed numerous mechanisms to survive inside a hostile host environment. The human pathogen Mycobacterium tuberculosis (M. tb) is thought to control the human immune response with diverse biomolecules, including a variety of exotic lipids. One prevalent M. tb-specific sulfated metabolite, termed sulfolipid-1 (SL-1), has been correlated with virulence though its specific biological function is not known. Recent advances in our understanding of SL-1 biosynthesis will help elucidate the role of this curious metabolite in M. tb infection. Furthermore, the study of SL-1 has led to questions regarding the significance of sulfation in mycobacteria. Examples of sulfated metabolites as mediators of interactions between bacteria and plants suggest that sulfation is a key modulator of extracellular signaling between prokaryotes and eukaryotes. The discovery of novel sulfated metabolites in M. tb and related mycobacteria strengthens this hypothesis. Finally, mechanistic and structural data from sulfate-assimilation enzymes have revealed how M. tb controls the flux of sulfate in the cell. Mutants with defects in sulfate assimilation indicate that the fate of sulfur in M. tb is a critical survival determinant for the bacteria during infection and suggest novel targets for tuberculosis drug therapy.
SpotSigs: robust and efficient near duplicate detection in large web collections

Motivated by our work with political scientists who need to manually analyze large Web archives of news sites, we present SpotSigs, a new algorithm for extracting and matching signatures for near duplicate detection in large Web crawls. Our spot signatures are designed to favor natural-language portions of Web pages over advertisements and navigational bars.The contributions of SpotSigs are twofold: 1) by combining stopword antecedents with short chains of adjacent content terms, we create robust document signatures with a natural ability to filter out noisy components of Web pages that would otherwise distract pure n-gram-based approaches such as Shingling; 2) we provide an exact and efficient, self-tuning matching algorithm that exploits a novel combination of collection partitioning and inverted index pruning for high-dimensional similarity search. Experiments confirm an increase in combined precision and recall of more than 24 percent over state-of-the-art approaches such as Shingling or I-Match and up to a factor of 3 faster execution times than Locality Sensitive Hashing (LSH), over a demonstrative "Gold Set" of manually assessed near-duplicate news articles as well as the TREC WT10g Web collection.
Common variants of Drosophila melanogaster Cyp6d2 cause camptothecin sensitivity and synergize with loss of Brca2.

Many chemotherapeutic agents selectively target rapidly dividing cells, including cancer cells, by causing DNA damage that leads to genome instability and cell death. We used Drosophila melanogaster to study how mutations in key DNA repair genes affect an organism’s response to chemotherapeutic drugs. In this study, we focused on camptothecin and its derivatives, topotecan and irinotecan, which are type I topoisomerase inhibitors that create DNA double-strand breaks in rapidly dividing cells. Here, we describe two polymorphisms in Drosophila Cyp6d2 that result in extreme sensitivity to camptothecin but not topotecan or irinotecan. We confirmed that the sensitivity was due to mutations in Cyp6d2 by rescuing the defect with a wild-type copy of Cyp6d2. In addition, we showed that combining a cyp6d2 mutation with mutations in Drosophila brca2 results in extreme sensitivity to camptothecin. Given the frequency of the Cyp6d2 polymorphisms in publcly available Drosophila stocks, our study demonstrates the need for caution when interpreting results from drug sensitivity screens in Drosophila and other model organisms. Furthermore, our findings illustrate how genetic background effects can be important when determining the efficacy of chemotherapeutic agents in various DNA repair mutants.
Detecting two dimensional symmetry protected topological order in a ground state wave function

Symmetry-protected topological states cannot be deformed to a trivial state so long as the symmetry is preserved, yet there is no local order parameter that can distinguish them from a trivial state. We demonstrate how to detect whether a two-dimensional ground state has symmetry-protected topological order; the measurements play a similar role as the topological entanglement entropy does for detecting anyons. For any finite Abelian onsite symmetry, the measurement completely determines the third cohomology class that characterizes the order. The proposed measurement is validated numerically using the infinite density matrix renormalization group for a model with ${\mathbb{Z}}_{2}$ symmetry-protected order.
Electromagnetic scattering from skew-symmetric metallic grids

In many applications for reflector antennas, the reflector is made from flexible, conducting material. The wires are weaved together, forming a very complex structure to study. So far, these mesh structures have been approximated by rectangular grids. In this study, the mesh geometry is approximated by a skew-symmetric grid. The FFT-conjugate gradient method (FFT-CGM) is employed to solve the problem of scattering from such grids. A convenient unit cell is chosen and utilized to study the effects of skewness on the reflection coefficients and current densities. Calculated values of the reflection coefficient for different angles of incidence for both the bonded and unbonded skewed gratings are presented and discussed. © 1993 John Wiley & Sons, Inc.
Capabilities as fundamental entitlements: Sen and social justice

Amartya Sen has made a major contribution to the theory of social justice, and of gender justice, by arguing that capabilities are the relevant space of comparison when justice-related issues are considered. This article supports Sen's idea, arguing that capabilities supply guidance superior to that of utility and resources (the view's familiar opponents), but also to that of the social contract tradition, and at least some accounts of human rights. But I argue that capabilities can help us to construct a normative conception of social justice, with critical potential for gender issues, only if we specify a definite set of capabilities as the most important ones to protect. Sen's "perspective of freedom" is too vague. Some freedoms limit others; some freedoms are important, some trivial, some good, and some positively bad. Before the approach can offer a valuable normative gender perspective, we must make commitments about substance.
Displacement effect in multicomponent chromatography

The study of interference effects is of fundamental importance in understanding multicomponent chromatography. In this work, a displacement effect is examined and shown to be able to explain the dominating interference effects in three major modes of chromatography—frontal, elution, and displacement—involving competitive isotherms. It is concluded that the concentration profile of a component usually becomes sharper due to the displacement effect from another component, while the concentration front of the displacer is usually diffused. Five factors that escalate the displacement effect in multicomponent elution were investigated. A binary elution with a competing modifier in the mobile phase was also discussed. This study was carried out using computer simulations based on a general nonlinear multicomponent rate equation model that considers axial dispersion, external mass transfer, intraparticle diffusion, and Langmuir isotherms. The use of the general model helps the visualization of the multicomponent interactions in chromatography under mass transfer conditions.
Trade, product cycles, and inequality within and between countries

. This paper incorporates Northern product innovation and product-cycle-driven technology transfer into the continuum-of-goods Heckscher-Ohlin model. The creation of very skill-intensive goods induces the North to transfer production of older, less skill-intensive goods to the South. These relocated goods are the most skill intensive by Southern standards. Hence, product cycles raise the relative demand for skilled workers and thus wage inequality within both regions. This runs contrary to the Stolper-Samuelson theorem, but accords well with the fact that wage inequality has risen in both Northern and Southern countries. Moreover, product cycles increase income inequality between countries. JEL classification: F1 Commerce international, cycles de produit, et inegalitea l’interieur des pays et entre eux. Ce memoire incorpore le processus d’innovation et de transfert de technologie engendre par le cycle du produit dans le Nord dans le continuum de produits d’un modele Hecksher-Ohlin. La creation de biens a forte intensite en habiletes amene le Nord a transferer la production de biens a moins forte intensite en habiletes vers le Sud. Ces biens relocalises sont ceux qui sont les plus intensifs en habiletes dans le Sud. En consequence, les cycles de produit augmentent la demande de main d’œuvre qualifiee et donc l’inegalite entre les regions. Voila qui ne va pas dans le sens de ce que le theoreme de Stolper-Samuelson suggere, mais s’accorde bien avec le fait que les inegalites de salaires augmentent dans le Nord et le Sud. De plus les cycles de produit augmentent l’inegalite entre pays. Meme si le transfert de technologie diminue l’ecart de revenu entre le Nord et le Sud, cet effet est plus que compense par l’effet de l’innovation de produit. Ce memoire examine aussi les effets de bien-etre des cycles de produit. Les cycles de produit engendrent des avantages pour le Nord et le Sud, et ameliorent le sort des travailleurs hautement qualifies dans les deux regions.
More evidence on income distribution and growth

Abstract It has been suggested that inequality is an unpleasant precondition for growth. This paper shows that the empirical evidence strongly supports the opposite view: that inequality is negatively correlated with growth. This result is robust across different inequality measures, and to many different specifications of the growth regression. Furthermore, inequality appears to have a negative effect on both democracies and non-democracies. Interaction terms between inequality and regime type, when included in the base regression, do not affect the sign or significance of the inequality variables.
Hold-up, Asset Ownership, and Reference Points

This paper reexamines some of the themes of the incomplete contracts literature—in particular, the hold-up problem and asset ownership—through a new theoretical lens, the idea that contracts serve as reference points (see Hart and Moore [2008]). We consider a buyer and seller who are involved in a (long-term) economic relationship where the buyer’s value and seller’s cost are initially uncertain. For the relationship to work out, the parties need to cooperate in ways that cannot be specified in an initial contract. Suppose that the parties write a rigid contract that fixes price. Such a contract works well in “normal” times because there is nothing to argue about: we assume that, in the absence of argument, the parties are willing to cooperate. However, if value or cost falls outside the normal range, one party will have an incentive to threaten to withhold cooperation unless the contract is renegotiated; that is, the party will engage in hold-up. For example, if value is unusually high, the seller will hold up the buyer to get a higher price, whereas if cost is unusually low, the buyer will hold up the seller to get a lower price. We suppose that hold-up transforms a friendly relationship into a hostile one. The consequence is that the parties withhold cooperation: they operate within the letter, rather than the spirit, of their (renegotiated) ∗ I am grateful to John Moore for discussions of some of the elements of this paper and to Bob Gibbons and Birger Wernerfelt for many helpful conversations. I would also like to thank Ronen Avraham, Mathias Dewatripont, Florian Englmaier, Rob Gertner, Victor Goldberg, Louis Kaplow, Josh Lerner, Bentley MacLeod, Jeremy Stein, Sasha Volokh, Abe Wickelgren, and Christian Zehnder for useful comments, and Georgy Egorov for excellent research assistance. Four referees, an editor (Larry Katz), and a second editor provided highly constructive input. Financial support from the U.S. National Science Foundation through the National Bureau of Economic Research is gratefully acknowledged.
High-fidelity quantum control using ion crystals in a penning trap

We provide an introduction to the use of ion crystals in a Penning trap [1, 2, 3, 4] forexperiments in quantum information. Macroscopic Penning traps allow for the contain-ment of a few to a few million atomic ions whose internal states may be used in quantuminformation experiments. Ions are laser Doppler cooled [1], and the mutual Coulomb re-pulsion of the ions leads to the formation of crystalline arrays [5, 6, 7, 8]. The structureand dimensionality of the resulting ion crystals may be tuned using a combination ofcontrol laser beams and external potentials [9, 10]. We discuss the use of two-dimensional 9Be+ ion crystals for experimental tests ofquantum control techniques. Our primary qubit is the 124 GHz ground-state electronspin flip transition, which we drive using microwaves [11, 12]. An ion crystal representsa spatial ensemble of qubits, but the effects of inhomogeneities across a typical crystalare small, and as such we treat the ensemble as a single effective spin. We are able toinitialize the qubits in a simple state and perform a projective measurement [1] on thesystem. We demonstrate full control of the qubit Bloch vector, performing arbitrary high-fidelity rotations (τπ ∼200 µs). Randomized Benchmarking [13] demonstrates an errorper gate (a Pauli-randomized π=2 and π pulse pair) of 8±1×10-4. Ramsey interferome-try and spin-locking [14] measurements are used to elucidate the limits of qubit coherencein the system, yielding a typical free-induction decay coherence time of T2 ∼2 ms, and alimiting T1ρ ∼688 ms. These experimental specifications make ion crystals in a Penningtrap ideal candidates for novel experiments in quantum control. As such, we brieflydescribe recent efforts aimed at studying the error-suppressing capabilities of dynamicaldecoupling pulse sequences [15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26], demonstratingan ability to extend qubit coherence and suppress phase errors [11, 12]. We concludewith a discussion of future avenues for experimental exploration, including the use of ad-ditional nuclear-spin-flip transitions for effective multiqubit protocols, the potential forhardware refinements to suppress qubit error rates well-below predicted fault-tolerancethresholds, and possibilities for single-ion addressing useful for the realization of complexentangled states.
THE ROLE OF RAM PRESSURE STRIPPING IN THE QUENCHING OF CLUSTER STAR FORMATION

Recent observations of galaxy clusters have shown that environmental effects apparently associated with the cluster begin to lower the star formation rates of galaxies at distances as great as three times the cluster virial radius. These observations may indicate preprocessing of cluster galaxies in groups or in the cluster core for galaxies on highly elliptical orbits, but may also imply that the environmental effects due to the cluster are directly affecting galaxies on their first infall. To explore these issues, we investigate different models of ram pressure stripping (RPS) as it acts on satellite galaxies in clusters and compare to observations of the radial star formation gradient in clusters. We calculate the location of the accretion shock around model clusters and use this as the radius of onset of RPS in the GALFORM semi-analytic model of galaxy formation. Comparison of the results of our model and previously considered, simpler ram pressure models with recent observations indicates that current data are unable to strongly discriminate between models of RPS due to the complex interplay of preprocessing effects at work. However, future observations of a larger sample of clusters will likely be able to place stronger constraints on the process of RPS and its role in shaping radial trends in and around clusters.
Distribution of microbial terpenoid lipid cyclases in the global ocean metagenome.

The bacterial terpenoid lipids known as hopanoids are fundamental tools for interpreting ancient microbial communities. Their degradation products, the hopanes, are found in sedimentary rocks throughout the geologic record. These compounds are presumed to be analogous to the sterols of eukaryotes, yet although the eukaryotic requirement for sterols is universal, hopanoid biosynthetic capacity is not ubiquitous among marine bacteria. Among the 9.8 million shotgun reads from the Sorcerer II Global Ocean Sampling (GOS) expedition, 148 contain putative coding sequence for bacterial squalene-hopene cyclases (SHCs). SHCs encoded by α-Proteobacteria potentially related to Rhodospirillaceae dominate these hits, especially in the open ocean and in tropical regions. Planctomycetes and β-Proteobacteria contribute more SHC-encoding sequences, and therefore presumably more hopanoid production, to coastal and temperate environments. Although sequences nominally related to α- and β-Proteobacteria outnumber other taxa in marine and coastal environments, there is large phylogenetic distance between GOS sequences and known species. Assuming that the environments sampled here are broadly representative of a wide range of surface ocean climates, depositional settings and temporal periods, the data suggest a fundamental function for Proteobacteria in the development of the geologic record of hopanes.
Polarization control for coherent fiber-optic systems using nematic liquid crystals

One of the obstacles to coherent fiber-optic communications is the unpredictable polarization drift which necessitates the use of an active polarization controlling system to match the polarizations of the signal and local oscillator. The polarization match must be maintained during the reset of any of the finite range components to prevent loss of data. A novel and practical system which uses three liquid-crystal devices for the polarization matching process is presented, and the required reset control algorithm and its derivation are described in detail. >
Palladium Based Micro-Membrane Hydrogen Gas Separator-Reactor in a Miniature Fuel Processor for Micro Fuel Cells

A novel palladium-based micromembrane has been fabricated and tested which has the potential to be used for carbon monoxide shift reaction and hydrogen gas separation in a miniature fuel processor for micro fuel cells. The micromembrane structure is built in silicon substrate, using standard MEMS microfabrication processes. The four layers, viz., copper, aluminum, spin-on-glass (SOG) and palladium form the composite micromembrane. Copper, aluminum and SOG serve as a structural support for the palladium film. Copper also acts as a catalyst in the shift reaction that converts unwanted carbon monoxide gas into hydrogen, which in turn is separated by the palladium micro-membrane. For a particular combination of thicknesses for various layers, the composite micro-membrane withstands a pressure gradient up to 1 atm. The micromembrane separates hydrogen from a 20% hydrogen balance nitrogen gas mixture at room temperature.
Double Field Theory of Type II Strings

We use double field theory to give a unified description of the low energy limits of type IIA and type IIB superstrings. The Ramond-Ramond potentials fit into spinor representations of the duality group O(D, D) and field-strengths are obtained by acting with the Dirac operator on the potentials. The action, supplemented by a Spin+ (D, D)-covariant self-duality condition on field strengths, reduces to the IIA and IIB theories in different frames. As usual, the NS-NS gravitational variables are described through the generalized metric. Our work suggests that the fundamental gravitational variable is a hermitian element of the group Spin(D, D) whose natural projection to O(D, D) gives the generalized metric.
Heegaard surfaces and measured laminations, II: Non-Haken 3–manifolds

A famous example of Casson and Gordon shows that a Haken 3-manifold can have an infinite family of irreducible Heegaard splittings with different genera. In this paper, we prove that a closed non-Haken 3-manifold has only finitely many irreducible Heegaard splittings, up to isotopy. This is much stronger than the Waldhausen conjecture. Another immediate corollary is that for any irreducible non-Haken 3-manifold M, there is a number N, such that any two Heegaard splittings of M are equivalent after at most N stabilizations.
LOCAL MONODROMY OF p-DIVISIBLE GROUPS

A p-divisible group over a field K admits a slope decomposition; associated to each slope λ is an integer m and a representation Gal(K) → GL m (D λ ), where D λ is the ℚ p -division algebra with Brauer invariant [λ]. We call m the multiplicity of λ in the p-divisible group. Let Go be a p-divisible group over a field k. Suppose that λ is not a slope of G 0 , but that there exists a deformation of G in which λ appears with multiplicity one. Assume that λ ≠ (s — 1)/s for any natural number s > 1. We show that there exists a deformation G/R of G 0 /k such that the representation Gal(FracR) → GL 1 (D λ ) has a large image.
Testing the expansion of a graph

We study the problem of testing the expansion of graphs with bounded degree d in sublinear time. A graph is said to be an @a-expander if every vertex set U@?V of size at most 12|V| has a neighborhood of size at least @a|U|. We show that the algorithm proposed by Goldreich and Ron [9] (ECCC-2000) for testing the expansion of a graph distinguishes with high probability between @a-expanders of degree bound d and graphs which are -far from having expansion at least @W(@a^2). This improves a recent result of Czumaj and Sohler [3] (FOCS-07) who showed that this algorithm can distinguish between @a-expanders of degree bound d and graphs which are -far from having expansion at least @W(@a^2/logn). It also improves a recent result of Kale and Seshadhri [12] (ECCC-2007) who showed that this algorithm can distinguish between @a-expanders and graphs which are -far from having expansion at least @W(@a^2) with twice the maximum degree. Our methods combine the techniques of [3], [9] and [12].
Hazardous Waste: Evolution of a National Environmental Problem

The evolution of hazardous waste into a national environmental problem is a puzzling phenomenon. The public and media perceive hazardous waste to be a major environmental and public health risk. Yet, although the problem of hazardous waste and its resultant contamination has long been known, no one took it seriously until about 1978. An interesting question is, Why did the public and media ignore hazardous waste for so long, particularly during a period of unprecedented public and media interest in the environment, especially pollution, in the late 1960s and throughout the 1970s?
THE INFLUENCE OF THE ANTERIOR LOBE OF THE PITUITARY BODY UPON THE GROWTH OF CARCINOMATA

1. The administration of emulsions of the anterior lobe of the ox pituitary increases very markedly the rate of growth of the primary tumor in rats inoculated with carcinoma. The growth of small tumors is accelerated relatively more than that of large tumors. 2. This acceleration is only evidenced, however, at a certain stage in the growth of the tumor, subsequent to the twentieth day succeeding inoculation. The administrations do not enhance the tendency of the tumors to metastasize. 3. Liver emulsion does not cause an acceleration of the growth of carcinomata in rats.
Wiki as a Teaching Tool

Wikis are one of many Web 2.0 components that can be used to enhance the learning process. A wiki is a web communication and collaboration tool that can be used to engage students in learning with others within a collaborative environment. This paper explains wiki usage, investigates its contribution to various learning paradigms, examines the current literature on wiki use in education, and suggests additional uses in teaching software engineering.
Parameter Estimation and Confidence Regions in the Method of Light Curve Simulations for the Analysis of Power Density Spectra

The method of light-curve simulations is a tool that has been applied to X-ray monitoring observations of active galactic nuclei for the characterization of the power density spectrum (PDS) of temporal variability and measurement of associated break frequencies (which appear to be an important diagnostic for the mass of the black hole in these systems as well as their accretion state). It relies on a model for the PDS that is fitted to the observed data. The determination of confidence regions on the fitted model parameters is of particular importance, and we show how the Neyman construction based on distributions of estimates may be implemented in the context of light-curve simulations. We believe that this procedure offers advantages over the method used in earlier reports on PDS model fits, not least with respect to the correspondence between the size of the confidence region and the precision with which the data constrain the values of the model parameters. We plan to apply the new procedure to existing RXTE and XMM-Newton observations of Seyfert I galaxies as well as RXTE observations of the Seyfert II galaxy NGC 4945.
Projective structures with degenerate holonomy and the Bers density conjecture

We prove the Bers density conjecture for singly degenerate Kleinian surface groups without parabolics.
Recursive robust estimation and control without commitment

Abstract In a Markov decision problem with hidden state variables, a posterior distribution serves as a state variable and Bayes’ law under an approximating model gives its law of motion. A decision maker expresses fear that his model is misspecified by surrounding it with a set of alternatives that are nearby when measured by their expected log likelihood ratios (entropies). Martingales represent alternative models. A decision maker constructs a sequence of robust decision rules by pretending that a sequence of minimizing players choose increments to martingales and distortions to the prior over the hidden state. A risk sensitivity operator induces robustness to perturbations of the approximating model conditioned on the hidden state. Another risk sensitivity operator induces robustness to the prior distribution over the hidden state. We use these operators to extend the approach of Hansen and Sargent [Discounted linear exponential quadratic Gaussian control, IEEE Trans. Automat. Control 40(5) (1995) 968–971] to problems that contain hidden states.
Steric influence of silyl groups in titanium- and lithium-mediated aldol condensations

Reactions of lithium enolates of α-silyloxyketones 1a, 1b, 2a, and 2b with benzaldehyde yield opposite diastereoselection depending upon the size of the silyl group, but all four titanium enolates lead to high diastereofacial selectivities. These results implicate a nonchelated transition structure which is insensitive to the steric size of the silyl group for the titanium-mediated aldol reactions. Ketone 1a is shown to give high selectivities for the two opposite syn adducts (99:1 with Ti; 10:90 with Li). Because it is readily prepared in monochiral form, 1a may offer advantages as a chiral precursor for preparation of either product stereochemistry, as desired.
A superconducting solenoid and press for permanent magnet fabrication

For the first time, a superconducting solenoid (SCM) was used to increase the remnant magnetization of sintered NdFeB permanent magnets (PMs). In particular, magnetic alignment of commercial-grade PM powder was improved by axial-die pressing the powder into 12.7-mm diameter cylindrical compacts in the 76.2-mm warm bore of a 9-T SCM. The press used to compact the powder is unique and was specifically designed for use with the SCM. Although the press was operated in the batch mode for this proof-of-concept study, its design is intended to enable automated production. In operation, a simple die and punch set made of nonmagnetic materials was filled with powder and loaded into a nonmagnetic press tube. The cantilevered press tube was inserted horizontally, on a carrier manually advanced along a track, into the SCM. The mechanical components and the SCM, in its liquid helium dewar, were specifically designed to allow for insertion and extraction of the magnetic powder and compacts, while operating the solenoid at 9 T. Compaction was achieved by pressing the punches between the closed end of the press tube and the hydraulic cylinder mounted on the opposite end. Improvements up to 10% in magnetization and 20% in energy products of the permanent magnets were obtained, as the alignment fields were increased above the 2-T maximum field of the electromagnets used in industry. For comparison, increases in magnetization of 3% are significant in the mature sintered magnet industry.
Amitriptyline disposition in young and elderly normal men

The disposition of a single parenteral or single oral dose of amitriptyline was followed in seven young (mean age 22 yr, range 21 to 23) and five elderly (mean age 71 yr, range 62 to 81) healthy men. The mean systemic clearance did not change with age (10.8 +/- 2.1 ml/min/kg in elderly and 12.5 +/- 2.3 ml/min/kg in young subjects). Mean t 1/2 was longer in the older (21.7 +/- 2.9 hr) than in the younger group (16.2 +/- 6.1 hr) as a result of an increase in the volume of distribution (17.1 +/- 2.4 and 14.1 +/- 2.0 l/kg). The bioavailability and the fraction of the drug bound to plasma proteins did not change with age. Single doses of amitriptyline were not well tolerated clinically by either elderly or young subjects, which confirms the need for a gradual buildup in the therapeutic regimen and for close clinical surveillance of elderly depressed patients treated with amitriptyline.
Optimization of multi-frequency techniques used for cell membrane capacitance estimation

Measurements of cell membrane capacitance serve as an indicator of cell membrane surface area and thus have traditionally been used in stimulus-secretion coupling to monitor exocytosis and endocytosis of secretory vesicles. In order to accurately monitor secretion, high-resolution methods of tracking small (10/sup -15/ F) changes in baseline capacitance must be utilized. Most presently used techniques require assumptions that are not appropriate under all recording conditions or suffer from a low signal-to-noise ratio (SNR). This paper proposes to improve upon current estimation techniques by developing an optimized multi-frequency sinusoidal stimulus waveform for accurate capacitance estimations. The waveform is designed by jointly optimizing the phase and voltage of individual frequency components so as to minimize the theoretical bound on the variance of the capacitance estimate, while maintaining a preselected limit on the overall stimulus magnitude.
Automatic test packet generation

Networks are getting larger and more complex, yet administrators rely on rudimentary tools such as ping and traceroute to debug problems. We propose an automated and systematic approach for testing and debugging networks called “Automatic Test Packet Generation” (ATPG). ATPG reads router configurations and generates a device-independent model. The model is used to generate a minimum set of test packets to (minimally) exercise every link in the network or (maximally) exercise every rule in the network. Test packets are sent periodically, and detected failures trigger a separate mechanism to localize the fault. ATPG can detect both functional (e.g., incorrect firewall rule) and performance problems (e.g., congested queue). ATPG complements but goes beyond earlier work in static checking (which cannot detect liveness or performance faults) or fault localization (which only localize faults given liveness results). We describe our prototype ATPG implementation and results on two real-world data sets: Stanford University's backbone network and Internet2. We find that a small number of test packets suffices to test all rules in these networks: For example, 4000 packets can cover all rules in Stanford backbone network, while 54 are enough to cover all links. Sending 4000 test packets 10 times per second consumes less than 1% of link capacity. ATPG code and the data sets are publicly available.
MIRAGE GAUGE COUPLING UNIFICATION AND TeV SCALE STRINGS

We consider gauge coupling unification in models with TeV scale strings and large compact dimensions realized as type IIB string orientifolds. Following an observation by Ibanez we show that the gauge couplings at low energies can behave as if they effectively unify at MU~2 × 1016 GeV with αU~1/24. This requires the σ model anomaly coefficients $b^{i'}_a$ not to be all equal and their ratio to the β-functions of minimally supersymmetric standard model βa to be a constant independent of the gauge group. If, in addition, $b^{i'}_a have a gauge group independent constant piece, the relation between the unified gauge coupling and the dilaton vev is modified so that there can be weakly coupled gauge theories arising from strongly coupled strings.
High resolution interface analysis

Abstract The structure and composition of interfaces in composites and other structural solids has important effects on their properties and is therefore of great interest. HREM and microspectroscopy are two of the most useful methods for examination of interfaces. HREM methods are the most advanced, and microspectroscopy methods are improving rapidly. The current image resolution limit is ∼ 1.6 A which is sufficient for most interface analysis purposes. The corresponding spatial resolution limit for microspectroscopy is determined by the current in small probes and temporal stability of the probe/specimen. Calculations of probe current vs. size are given and it is shown that current spatial resolution for EELS, for edges containing several thousand counts, is about 5 nm. The effect of chemical bonding on electron energy loss absorption edges of silicon in its important ceramic compounds is presented and briefly discussed. Examples of high resolution analysis in several composites and a multiphase ceramic are presented.
Review—Mean Flow in Turbulent Boundary Layers Disturbed to Alter Skin Friction

A comparative evaluation is made of recent developments in methods for the reduction of boundary layer drag, encompassing longitudinal surface riblets, 'outer layer' devices, (OLDs) and longitudinal convex surface curvature. The boundary layer of a surface with a longitudinal concave curvature is also studied, to complement the convex case results. The net drag reductions achievable by both riblets and OLDs are noted to be a rather modest 10 percent. Boundary layers exhibit asymmetric response to streamwise surface curvatures, with the response being slower for the case of a concave than a convex curvature.
Graph Ramsey theory and the polynomial hierarchy

Summary form only given, as follows. In the Ramsey theory of graphs F/spl rarr/(G, H) means that for every way of coloring the edges of F red and blue F will contain either a red G or a blue H as a subgraph. The problem ARROWING of deciding whether F/spl rarr/(G, H) lies in /spl Pi//sub 2//sup P/=coNP/sup NP/ and it was shown to be coNP-hard by S.A. Burr (1990). We prove that ARROWING is actually /spl Pi//sub 2//sup P/-complete, simultaneously settling a conjecture of Burr and providing a natural example of a problem complete for a higher level of the polynomial hierarchy. We also consider several specific variants of ARROWING, where G and H are restricted to particular families of graphs. We have a general completeness result for this case under the assumption that certain graphs are constructible in polynomial time. Furthermore we show that STRONG ARROWING, the version of ARROWING for induced subgraphs, is /spl Pi//sub 2//sup P/-complete.