cssi/SciSciGPT-SciSciNet huggingface dataset:
Parametric Analysis of the Kalina Cycle

The Kalina Cycle utilizes a mixture of ammonia and water as the working fluid in a vapor power cycle. When the liquid mixture is heated the more volatile ammonia tends to vaporize first and at a lower temperature than does pure water. This property of ammonia-water mixtures makes possible a better match to the enthalpy-temperature curve of a hot gas heat source such as a gas turbine exhaust and also permits circulation of fluids of different composition in different parts of the cycle. Taking advantage of the latter feature, condensation (absorption) can be done at slightly above atmospheric pressure with a low concentration of ammonia, while heat input is at a higher concentration for optimum cycle performance. Computer models have been used to optimize a simplified form of the cycle and to compare results for a more complex version proposed by El-Sayed and Tribus. A method of balancing the cycle was developed and key parameters for optimizing the cycle identified.
Cracks and fins in sulfate sand: Evidence for recent mineral-atmospheric water cycling in Meridiani Planum outcrops?

Gypsum dunes at White Sands National Monument, New Mexico, provide an excellent analog to sulfate-rich eolian outcrops on Meridiani Planum, Mars, as characterized by the Rover Opportunity. Numerous outcrops imaged by Opportunity contain polygonal cracks that crosscut bedding and extend across most surfaces of boulders. Some of these cracks are associated with millimeter-thick platy fins that protrude as much as a few centimeters above outcrops. Similar cracks crosscut bedding at White Sands on erosional stoss slopes and in pedestals of cemented dune sand. The cracks at White Sands form in response to cementation of damp gypsum sand followed by contraction due to dehydration. During warm seasons, cracked sand is dry and cracks rarely grow, although some may form after rainstorms. Two types of fins form along cracks and differentially eroded laminae. White fins represent subsurface differential cementation along cracks followed by differential erosion. Tan fins form due to cementation of crack edges and laminae on exposed dune surfaces. Wind-blown sediment adheres to damp tan fins. Similar processes may be important for crack and fin formation in Meridiani Planum outcrops, implying recent water cycling between sulfate outcrops and the Martian atmosphere.
Gamma-ray burst dust echoes revisited : Expectations at early times

Gamma-ray burst (GRB) dust echoes were first proposed as an alternative explanation for the supernova-like (SN-like) components to the afterglows of GRB 980326 and GRB 970228. However, the spectroscopic identification of Type Ic SN 2003dh associated with GRB 030329, as well as the identification of SN-like components of the afterglows of other GRBs, appears to have confirmed the GRB/SN paradigm. However, the likely progenitors of Type Ic SNe are Wolf-Rayet WC stars, and late-type WC stars have been observed to be surrounded by dust at a distance of 1014-1015 cm from the star. Consequently, we revisit the possibility of GRB dust echoes, not on a timescale of weeks after the burst but on a timescale of minutes to hours. We find that if the optical flash is sufficiently bright and the jet sufficiently wide, GRB afterglows may be accompanied by chromatic variations on this timescale. From these signatures, model parameters such as the inner radius of the dust distribution and the initial opening angle of the jet may be deduced. With rapid and regular localizations of GRBs by HETE-2, INTEGRAL, and now Swift, and new and improved robotic telescope systems, these early-time GRB dust echoes may soon be detected. We describe in greater detail one such robotic telescope system, called PROMPT, which the University of North Carolina at Chapel Hill is building at the Cerro Tololo Inter-American Observatory.
Possible use of synchrotrons as post-acceleration boosters for tandems

Abstract The recent development of a high intensity negative ion source and the demonstration that intense heavy ion beam bursts can be accelerated by a large tandem make synchrotrons a possibly attractive alternative when considering different types of tandem injected heavy ion booster accelerators.
The Close Limit of Colliding Black Holes: An Update

The collision of binary black holes is one of the primary expected sources of gravitational waves to be detected by the broadband interferometric gravitational wave telescopes currently under construction, like the LIGO project in the US, the British/German GEO project, the TAMA project in Japan and the French/Italian VIRGO project. A collision of two binary black holes can be divided into three distinct regimes. Initially, the black holes spiral around each other in quasi-Newtonian orbits. The radius of the orbits decrease due to the emission of gravitational radiation. Let us call this period the “inspiral” phase. The gravitational waves produced during this phase are well described by the post-Newtonian approximation. Notice that such an approximation does not provide a good description of the whole spacetime, since it breaks down close to each hole (to first approximation, the holes are singular point particles), but as long as the holes are far apart, this is not expected to be relevant from the point of view of the waveforms observed at infinity.∗) The gravitational waves from this phase of the collision correspond to a quasi-regular sinusoid whose frequency and amplitude increases with time as the holes start getting closer to each other, known as the “chirp”. Good descriptions of this approximation applied to the binary black hole case and appropriate references can be found in Blanchet et al. 2) When the separation of the holes is around 10 to 12 times the mass of each individual holes, it is expected that the post-Newtonian approximation breaks down. It is not completely clear what is the extent of the breakdown, since the post-Newtonian approximation leads to an asymptotic perturbation series. In fact, attempts are currently being made to extend the validity of the domain of the approximation using Pade approximants. 3) In any event, there will be a limiting separation of the holes such that if they are any closer, one cannot use the post-Newtonian approximation. The domain that starts at that point and continues up to the point in which the
Geometric quantization of real minimal nilpotent orbits

Abstract In this paper, we begin a quantization program for nilpotent orbits OR of a real semisimple Lie group GR. These orbits arise naturally as the coadjoint orbits of GR which are stable under scaling, and thus they have a canonical symplectic structure ω where the GR-action is Hamiltonian. These orbits and their covers generalize the oscillator phase space T ∗ R n , which occurs here when GR = Sp(2n, R) and OR is minimal. A complex structure J polarizing OR and invariant under a maximal compact subgroup KR of GR is provided by the Kronheimer-Vergne Kaehler structure (J, ω). We argue that the Kaehler potential serves as the Hamiltonian. Using this setup, we realize the Lie algebra ℷ R of GR as a Lie algebra of rational functions on the holomorphic cotangent bundle T ∗ Y where Y = (OR, J). Thus we transform the quantization problem on OR into a quantization problem on T ∗ Y . We explain this in detail and solve the new quantization problem on T ∗ Y in a uniform manner for minimal nilpotent orbits in the non-Hermitian case. The Hilbert space of quantization consists of holomorphic half-forms on Y. We construct the reproducing kernel. The Lie algebra ℷ R acts by explicit pseudo-differential operators on half-forms where the energy operator quantizing the Hamiltonian is inverted. The Lie algebra representation exponentiates to give a minimal unitary ladder representation of a cover of GR. Jordan algebras play a key role in the geometry and the quantization.
Trilepton signal of grand unified models at the Tevatron

Abstract At the Tevatron, the most promising channel to detect supersymmetry is three leptons plus missing energy, where the leptons are e 's and/or μ 's. This final state appears from the production of chargino and second lightest neutralino. However in grand unified models with universal scalar masses at the grand unified scale, this final state mostly consists of τ 's which are hard to detect. We show that for some regions of nonuniversality in the scalar masses at the GUT scale based on unifying groups like SU(5) or SO(10), the final state mostly consists of 3 l+ E / T and τll+ E / T , where the first mode has very high detection efficiency. We also show that these models can have enough events in these modes to be detected in RUN II/III.
The Effect of Inlet and Exit Losses on Free Convective Laminar Flow in the Trombe Wall Channel

A numerical solution for two-dimensional free convective laminar flow in the Trombe wall channel has recently been presented by Akbari and Borgers (1). Their analysis assumed no flow losses in the channel entrance and exit, other than the exit dynamic head (loss coefficient k=1), however the actual coefficient for combined inlet and exit losses is probably 2 < k < 5. In the present study, the convective terms of the momentum and energy equations are linearized through an Oseen-type approximation. A closed-form series solution to the resulting partial differential equations is obtained. Results are presented for dimensionless temperature and velocity field, flow rate and heat transfer; in terms of loss coefficient, surface temperature ratio, and Grashof number. As expected, vent loss reduces flow rate significantly: for loss coefficient k = 5, flow rate is reduced by about 70 percent relative to k = 1. Surprisingly, at high Grashof number, vent loss can cause a significant ( about 60 percent) increase in heat transfer. Reduction in flow rate occurs entirely due to flow velocity decrease in the region near the channel center, which contributes negligibly to the total heat delivery.
Oxidative free-radical cyclization of allylic α-chloromalonates. Synthesis of (±)-avenaciolide.

Abstract Oxidative free-radical cyclization of α-chloromalonate 9 with Mn(OAc)3·2H2O and Cu(Oac)2·H2O in acetic acid at 75 °C provides 82% of lactones 10a and 10b. Hydroboration of 10 followed by oxidation affords acids 12, which are converted to avenaciolide precursor 15 in 32% overall yield from 9 by decarboxylation and cyclization.
Ethnicity, Politics and Economic Performance

The paper investigates the effects of ethnic diversity on economic performance. Previous studies have found that diversity has various detrimental microeconomic effects, tending to reduce public sector performance, and has large detrimental effects on the overall growth rate. I develop a simple model of the effect of ethnic diversity on a government decision problem in which there is a tradeoff between growth and distribution, in the contexts of democracy and dictatorship. I find that in democracy ethnic diversity has no effect upon the decision, whereas in dictatorship ethnic diversity leads to a government choice which reduces the growth rate. I then test these propositions on two data sets. The first is for 94 countries over the period 1960–1990. I find that whether diversity adversely affects overall economic growth depends upon the political environment. Diversity is highly damaging to growth in the context of limited political rights, but is not damaging in democracies. The second is for World Bank projects in 89 countries. I find that the same relationship between diversity and democracy affects the proportion of projects which are successful.
Effects of Shadows on Photocurrent Compensated Integrated Circuits

Simple calculations show that high-z components such as wires, capacitors, and solder bonds can easily cast shadows with edges only 25 ?m wide when illuminated with a low energy (E < 60 keV) x-ray beam. If one of these shadows falls between a photocurrent compensating diode-transistor pair, the mismatch in dose can drastically reduce the transient hardness of the integrated circuit. Results of pulsed x-ray tests on the Texas Instruments RSN 54L 71 R-S flip-flop and RSN 54L 00 quad two input nand gate showed that the upset threshold of a given state of the flip-flop was lowered by as much as a factor of 29 and the nand gate by a factor of 5.7.
Expertise, Subversion, and Bureaucratic Discretion

This article examines a legislature's delegation of policy-making authority to an imperfectly controlled, expert bureaucrat. The legislature can reduce the bureaucrat's expertise advantage through costly investigations of its own before delegating. Further, the bureaucrat is granted discretionary bounds by the legislature, but can subvert legislative dictates by stepping beyond them at some cost. I analyze the interaction of preference divergence, investigation cost to the legislature, and subversion cost to the bureaucrat on the decision to delegate. The model shows that, because of the equilibrium effect of subversion on discretion, bureaucrats will want subversion of legislative dictates to be difficult, while legislators want it to be relatively easy. It also highlights an indirect effect between preference divergence and discretion: preference divergence leads the legislature to become more expert on policy matters, which leads it to delegate less. Delegation of policy-making authority from legislatures to bureaucrats poses fundamental questions about policy making in an administrative state. Some of these questions, such as why legislatures would ever delegate and how they can cope with the control problem delegation creates, have been extensively studied by economists and political scientists. An issue that has until recently received less attention is what explains the variation in delegation patterns across policy areas. This article is an effort to contribute to that part of the study of legislative-bureaucratic interaction. Delegation is often a concession to expertise; thus the cost of alternative forms of expertise is important in understanding this control problem. The extent of the bureaucracy's technical superiority does not arise exogenously. A legislature has a number of other institutional choices available to it, such as creating its own experts in the legislative branch, or acquiring expertise itself. The costs of other sources of expertise will vary with the technicalities
Reversible basal plane hydrogenation of graphene.

We report the chemical reaction of single-layer graphene with hydrogen atoms, generated in situ by electron-induced dissociation of hydrogen silsesquioxane (HSQ). Hydrogenation, forming sp3 C−H functionality on the basal plane of graphene, proceeds at a higher rate for single than for double layers, demonstrating the enhanced chemical reactivity of single sheet graphene. The net H atom sticking probability on single layers at 300 K is at least 0.03, which exceeds that of double layers by at least a factor of 15. Chemisorbed hydrogen atoms, which give rise to a prominent Raman D band, can be detached by thermal annealing at 100∼200 °C. The resulting dehydrogenated graphene is “activated” when photothermally heated it reversibly binds ambient oxygen, leading to hole doping of the graphene. This functionalization of graphene can be exploited to manipulate electronic and charge transport properties of graphene devices.
Dimension as a Key to the Neutrino Mechanism of Core-collapse Supernova Explosions

We explore the dependence on spatial dimension of the viability of the neutrino heating mechanism of core-collapse supernova explosions. We find that the tendency to explode is a monotonically increasing function of dimension, with three dimensions (3D) requiring ~40%-50% lower driving neutrino luminosity than one dimension and ~15%-25% lower driving neutrino luminosity than two dimensions (2D). Moreover, we find that the delay to explosion for a given neutrino luminosity is always shorter in 3D than 2D, sometimes by many hundreds of milliseconds. The magnitude of this dimensional effect is much larger than the purported magnitude of a variety of other effects, such as nuclear burning, inelastic scattering, or general relativity, which are sometimes invoked to bridge the gap between the current ambiguous and uncertain theoretical situation and the fact of robust supernova explosions. Since real supernovae occur in three dimensions, our finding may be an important step toward unraveling one of the most problematic puzzles in stellar astrophysics. In addition, even though in 3D, we do see pre-explosion instabilities and blast asymmetries, unlike the situation in 2D, we do not see an obvious axially symmetric dipolar shock oscillation. Rather, the free energy available to power instabilities seems to be shared by more and more degrees of freedom as the dimension increases. Hence, the strong dipolar axisymmetry seen in 2D and previously identified as a fundamental characteristic of the shock hydrodynamics may not survive in 3D as a prominent feature.
Strichartz estimates on Kerr black hole backgrounds

We study the dispersive properties for the wave equation in the Kerr space-time with small angular momentum. The main result of this paper is to establish Strichartz estimates for solutions of the aforementioned equation. As an application, we then prove global well-posedness and uniqueness for the energy critical semilinear wave equation.
Roles of repetitive sequences

Abstract Repetitive sequences are ubiquitous in the DNA of eukaryotes, some as tandem arrays and others interspersed widely in the genome. Repetitive sequences have special roles in genome evolution, which increasingly detailed sequence information is helping to elucidate. Processes, including meiotic crossing over (equal and unequal), unequal mitotic sister chromatid exchange, gene conversion and transposition, with or without multiplication, can foster homogeneity of the members of a repeat family (concerted evolution) and turnover of the whole genome. Some examples are considered. Tandem repeats, satellite and minisatellite sequences are considered as well as telomeric repeats. For a minisatellite locus, in which the frequency of length mutations has been measured, comparisons are made with expectations due to unequal sister chromatid exchange, and qualitative agreement is found. Interspersed repeats, of which Alu sequences are discussed as an important example, can through unequal recombination lead to a loss or duplication of the DNA between the recombination sites and hence to genetic disease or to gene duplication. It is argued that the rate of unequal Alu recombination may be quite high in the human genome.
Price Stickiness and Customer Antagonism

Managers often state that they are reluctant to vary prices for fear of "antagonizing customers." However, there is no empirical evidence that antagonizing customers through price adjustments reduces demand or profits. We use a 28-month randomized field experiment involving over 50,000 customers to investigate how customers react if they buy a product and later observe the same retailer selling it for less. We find that customers react by making fewer subsequent purchases from the firm. The effect is largest among the firm's most valuable customers: those whose prior purchases were most recent and at the highest prices.
On the nature and visibility of crater-associated streaks on Mars

The paper considers Mariner 9 and Viking data that contradict Kuzmin's (1975) hypothesis that all crater-associated wind streaks on Mars are depositional and consist of unresolved barchan-like dunes. According to Kuzmin's hypothesis, any streak can appear either bright or dark relative to its surroundings depending on the sun's position. The spacecraft images, however, show examples of dark and light streaks visible at the same azimuth angle of the sun. Evidence that bright and dark streaks differ both in morphology and in character is considered. It is suggested that the common ragged dark streaks are probably erosion scars while most bright streaks probably represent accumulations of bright dust-storm fallout.
Monetary Policy Preferences of Individual FOMC Members: A Content Analysis of the Memoranda Of Discussion

The Memoranda of Discussion provide detailed records of Federal Open Market Committee (FOMC) meeting deliberations. Procedures are developed for coding the textual data in the Memoranda and assessing the reliability of those codings. The codings are then used in the estimation of parameters of individual FOMC members' reaction functions. Data from the 1970 to 1976 period are employed in the estimation. In the future, similar methods could be used to analyze newly released transcripts of FOMC meetings held after 1976.
Overview of metrics and their correlation patterns for multiple-metric topology analysis on heterogeneous graph ensembles.

This study is an overview of network topology metrics and a computational approach to analyzing graph topology via multiple-metric analysis on graph ensembles. The paper cautions against studying single metrics or combining disparate graph ensembles from different domains to extract global patterns. This is because there often exists considerable diversity among graphs that share any given topology metric, patterns vary depending on the underlying graph construction model, and many real data sets are not actual statistical ensembles. As real data examples, we present five airline ensembles, comprising temporal snapshots of networks of similar topology. Wikipedia language networks are shown as an example of a nontemporal ensemble. General patterns in metric correlations, as well as exceptions, are discussed by representing the data sets via hierarchically clustered correlation heat maps. Most topology metrics are not independent and their correlation patterns vary across ensembles. In general, density-related metrics and graph distance-based metrics cluster and the two groups are orthogonal to each other. Metrics based on degree-degree correlations have the highest variance across ensembles and cluster the different data sets on par with principal component analysis. Namely, the degree correlation, the $s$ metric, their elasticities, and the rich club moments appear to be most useful in distinguishing topologies.
Comparative Economic Analysis of Concentrating Solar Technologies

One of the noted benefits of concentrating photovoltaics (PV) is the reduced cell area which results in reduction of the overall system cost. A variety of studies have looked at the cost for concentrating PV systems and made comparisons to concentrating solar thermal power plants, typically resulting in concentrating solar thermal power having lower system costs. Recently, a widespread design space was assessed for the potential efficiency improvements possible with a coupled hybrid PV/thermal solar energy system for electricity generation. The analysis showed that modest efficiency improvements could be made but no assessment of the economic impact was made. Although modest efficiency gains can be made, such a hybrid system requires more components than one of the conventional stand alone concentrating solar power plant on its own resulting in significantly different system costs. As a result, we look to compare the overall system costs of three different solar power technologies: concentrating PV, concentrating solar thermal, and the concentrating hybrid approach. Additionally, we will focus on documenting the necessary hybrid efficiencies to make a hybrid system competitive as well as the feasibility and means for achieving these efficiencies.
Stereospecific cross-coupling reactions of aryl-substituted tetrahydrofurans, tetrahydropyrans, and lactones.

The stereospecific ring-opening of O-heterocycles to provide acyclic alcohols and carboxylic acids with controlled formation of a new C–C bond is reported. These reactions provide new methods for synthesis of acyclic polyketide analogs with complex stereochemical arrays. Stereoselective synthesis of the cyclic template is utilized to control relative configuration; subsequent stereospecific nickel-catalyzed ring-opening affords the acyclic product. Aryl-substituted tetrahydrofurans and tetrahydropyrans undergo nickel-catalyzed Kumada-type coupling with a range of Grignard reagents to furnish acyclic alcohols with high diastereoselectivity. Enantioenriched lactones undergo Negishi-type cross-coupling with dimethylzinc to afford enantioenriched carboxylic acids. Application in a two-step enantioselective synthesis of an anti-dyslipidemia agent is demonstrated.
Electrocardiographic conduction disturbances in association with low-level lead exposure (the Normative Aging Study)

Recent research indicates that cumulative exposure to lead may be more toxic than previously thought. This study was undertaken to examine the relation of low-level lead exposure to electrocardiographic (ECG) conduction disturbances among 775 men who participated in the Normative Aging Study (average age 68 years; range 48 to 93). We used K-x-ray fluorescence to measure lead levels in the tibia and patella, and graphite furnace atomic absorption spectroscopy to measure blood lead levels. The mean (SD) values for blood lead, tibia lead, and patella lead were 5.8 (3.4) microg/dl, 22.2 (13.4) microg/g, and 30.8 (19.2) microg/g, respectively. Bone lead levels were found to be positively associated with heart rate-corrected QT and QRS intervals, especially in younger men. Specifically, in men or = 65 years of age. After adjustment for age and for serum high-density lipoprotein (HDL) level, a 10 microg/g increase in tibia lead was associated with an odds ratio (OR) of 2.23 (95% CI, 1.28 to 3.90) for intraventricular block in men or = 65 years of age. Blood lead level was not associated with any of the ECG outcomes examined. The results suggest that cumulative exposure to lead, even at low levels, may depress cardiac conduction.
Endothelial Cell Fibrinolytic Assembly

Endothelial cells play a critical role in thromboregulation by controlling the assembly of fibrinolytic constituents on the membrane. The assembly system illustrated in FIGURE 6 is characterized by the binding of circulating glu-plasminogen to a membrane receptor (Pathway 1). A membrane-associated protease (possibly plasmin) converts the inactive zymogen into a catalytically more efficient zymogen lys-plasminogen (Pathway 2). T-PA binds to a specific receptor, retains its catalytic activity, and is protected from its natural inhibitor PAI-1. The membrane provides a favorable environment for plasmin generation (Pathway 3) at the vessel surface and contributes to the maintenance of a physiological nonthrombogenic state. The immobilization and surface activation of plasminogen provides an important mechanism for localizing proteolytic activity at the surface of other cells such as macrophages and tumor cells. Lp(a), a plasminogen-like lipoprotein, by competing at the endothelial surface for plasminogen binding down-regulates endothelial cell plasmin generation and may thus promote localized thrombogenesis that over a period of time contributes to progressive atherosclerosis.
Competitive equilibrium with intuitionistic agents

This paper studies an economy whose agents perceive their consumption possibilities subjectively, and whose preferences are defined on what they subjectively experience, rather than on those alternatives that are objectively present. The model of agents’ perceptions is based on intuitionistic logic. Roughly, this means that agents reason constructively: a solution to a problem exists only if there is a construction by which the problem can be solved. The theorems that can be proved determine how an agent perceives a set of alternatives. A dual model relates perceived alternatives to a shared language, which the agents use in trading. So perceptions relate objective alternatives to an agent’s subjective view of them, and reporting dually relates an agent’s subjective world to a shared language. It turns out that an appropriately modified notion of competitive equilibrium always exists. However, in contrast with standard results in economic theory, competitive equilibrium need not be efficient.
The optical spectrum of the sn 1006 supernova remnant revisited

We present the deepest optical spectrum acquired to date of Balmer-dominated shocks in the northwest rim of SN 1006. We detect the broad and narrow components of Hα, Hβ, and Hγ and report the first detection of the He I λ6678 emission line in this supernova remnant. We may have detected, at the 1.5 σ level, faint He II λ4686 emission. We measure a full width at half-maximum of 2290 ± 80 km s-1 in the broad-component Hα line, with broad-to-narrow flux ratios of 0.84 and 0.93 in Hα and Hβ, respectively. To match these observations, our nonradiative shock models require a low degree of electron-proton equilibration at the shock front, Te/Tp ≤ 0.07, and a shock speed of 2890 ± 100 km s-1 . These results agree well with an earlier analysis of ultraviolet lines from SN 1006. The He I/Hα and He I/He II flux ratios also indicate low equilibration. Furthermore, our models match the observations for mostly ionized (~90%) preshock H and mostly neutral (70%) preshock He, respectively. We conclude that the high H ionization fraction cannot be explained by either photoionization from the reverse shock or relic ionization from EUV photons released in the A.D. 1006 supernova. The most plausible explanation appears to be photoionization from the Galactic Lyman continuum.
What can spatial frequency analysis tell us about inter-observer variability in mammogram reading?

The differences in the interpretation of perceived findings are one of the most important elements in breast cancer detection. Several studies have shown that radiologists do not necessarily agree with each other, which is reflected in wide ranges of sensitivity and specificity, when groups of radiologists read the same mammogram cases. This variability, however, is not well understood. The characteristics of the areas where the observers agree or do not agree have not been widely explored. In this paper we compare the agreement rates of observers belonging to two different groups, namely, mammographers and residents, when reading a test set of mammograms. We determine the spatial frequency characteristics of areas that yield high agreement, as well as that of areas that yield high disagreement, among the observers.
N,N'-bis[4-(N-alkylamidino)phenyl]homopiperazines as anti-Pneumocystis carinii agents.

Abstract The synthesis, anti-Pneumocystis carinii activity and DNA binding properties of eight new N,N′-bis[4-(N-alkylamidino)phenyl]homopiperazines are reported. Compounds 2 and 8 were the most potent and caused about 70% inhibition of Pneumocystis carinii growth in a cell culture model at 1 μM concentrations.
A mild and catalytic decarboxylation of α-iminoacids by tributyl phosphine

Abstract α-Iminoacids, prepared from α-keto acids and primary amines, undergo decarboxylation to the corresponding imines by reaction with a catalytic amount of tributylphosphine. No reaction has been observed with α-keto acids or their phenyl-hydrazone, tosyl-hydrazone or oxime derivatives under the same conditions. However, carboxy-azines react rapidly with tributylphosphine and give the corresponding aldazines quantitatively. The mechanism of this reaction is also discussed.
A constant-time optimal parallel string-matching algorithm

Given a pattern string, we describe a way to preprocess it. We design a CRCW-PRAM constant time optimal parallel algorithm for finding all occurrences of the (preprocessed) pattern in any given text.
Opportunistic Transient-Fault Detection

CMOS scaling continues to enable faster transistors and lower supply voltage, improving microprocessor performance and reducing per-transistor power. The downside of scaling is increased susceptibility to soft errors due to strikes by cosmic particles and radiation from packaging materials. The result is degraded reliability in future commodity microprocessors. The authors target better coverage while incurring minimal performance degradation by opportunistically using redundancy
The Role of Helium Stars in the Formation of Double Neutron Stars

We have calculated the evolution of 60 model binary systems consisting of helium stars in the mass range of MHe ¼ 2:5 6 Mwith a 1.4 Mneutron star companion to investigate the formation of double neutron star systems. Orbital periods ranging from 0.09 to 2 days are considered, corresponding to Roche lobe over- flow starting from the helium main sequence to after the ignition of carbon burning in the core. We have also examined the evolution into a common envelope phase via secular instability, delayed dynamical instability, and the consequence of matter filling the neutron star's Roche lobe. The survival of some close He-star neutron star binaries through the last mass transfer episode (either dynamically stable or unstable mass trans- fer phase) leads to the formation of extremely short-period double neutron star systems (with Pd0:1 days). In addition, we find that systems throughout the entire calculated mass range can evolve into a common enve- lope phase, depending on the orbital period at the onset of mass transfer. The critical orbital period below which common envelope evolution occurs generally increases with MHe. In addition, a common envelope phase may occur during a short time for systems characterized by orbital periods of 0.1-0.5 days at low He- star masses (� 2.6-3.3 M� ). The existence of a short-period population of double neutron stars increases the predicted detection rate of in-spiral events by ground-based gravitational-wave detectors and impacts their merger location in host galaxies and their possible role as � -ray burst progenitors. We use a set of population synthesis calculations and investigate the implications of the mass transfer results for the orbital properties of DNS populations. Subject headings: binaries: close — stars: evolution — stars: formation — stars: neutron
SERT II - Mission, thruster performance, and in-flight thrust measurements

The SERT II spacecraft, containing two 15-cm-diam mercury electron bombardment ion thrusters, was launched February 3, 1970. One thruster operated for 5 months of the 6month mission goal. The over-all thruster efficiency 0.68 remained constant; the specific impulse was about 4200 sec; and the thrust was 28 mN (6.3 mlb) for a thruster input power of 850 w. A second flight thruster operated 3 months in space. Both thrusters failed due to sudden shorts between high voltages which have since been determined as resulting from the neutralizer location. This paper compares the thrusters performance with corresponding preflight ground testing. The thrust in flight, determined by three different methods, is presented. In addition, the SERT II spacecraft and mission are described.
Determination of longitudinal aerodynamic derivatives from steady-state measurement of an aircraft

A method for the estimation of aerodynamic derivatives from steady-state symmetric flight data is developed. The derivatives considered are the longitudinal static stability and control derivatives, damping derivatives due to tail, and the derivatives expressing the speed effect on the lift and pitching moment coefficients. The method is an extension of the well known theory of longitudinal static stability and control, and corresponding flight data interpretation. Measured data is assumed in the form of trim curves and lift vs angle of attack. The expressions for the derivative estimates are in the form of algebraic relationships containing known constants, and directly or indirectly measured quantities.
Log-concavity of the partition function

We prove that the partition function $$p(n)$$ is log-concave for all $$n>25$$ . We then extend the results to resolve two related conjectures by Chen and one by Sun. The proofs are based on Lehmer’s estimates on the remainders of the Hardy–Ramanujan and the Rademacher series for $$p(n)$$ .
Spin Chains in N = 6 Superconformal Chern-Simons-Matter Theory

In this note we study spin chain operators in the N = 6 Chern-Simons-matter theory recently proposed by Aharony, Bergman, Jafferis and Maldacena to be dual to type IIA string theory in AdS4 × CP 3 . We study the two-loop dilatation operator in the gauge theory, and compare to the Penrose limit on the string theory side.
Transverse instability of gravity–capillary solitary waves

Gravity–capillary solitary waves of depression that bifurcate at the minimum phase speed on water of finite or infinite depth, while stable to perturbations along the propagation direction, are found to be unstable to transverse perturbations on the basis of a long-wave stability analysis. This suggests a possible generation mechanism of the new class of gravity–capillary lumps recently shown to also bifurcate at the minimum phase speed.
Remote asymmetric induction: Synthesis of C-linked α-galactoserine and homoserine derivatives by electrophilic amination

Abstract A high diastereoselectivity (98%) for electrophilic amination of compound 9 using di- t -butyl azodicarboxyl ester as an electrophile was achieved. A similar reaction with compound 13 having achiral oxazolidinone was studied to examine 1,4-remote asymmetric induction. In the latter, a selectivity of 6.5:1 demonstrated the effect of α-galactosyl moiety, responsible for inducing the induction from the remote site.
Lithospheric evolution of the Pacific–North American Plate Boundary considered in three dimensions

Abstract Tomographic images developed using the combined seismic networks of California and Nevada provide a three-dimensional view into Neogene Pacific–North American plate boundary evolution. Images reveal structures similar in size and spatial distribution to the large-scale structures observed at the surface. A prominent linear anomaly in the mantle is imaged beneath the western foothills to a depth of 70–90 km. Called the Sierran Foothill Anomaly (SFA), this 1–2% high-velocity structure extends the length of the physiographic Sierra Nevada Mountains. Much of the velocity increase is thermal in origin, with a first episode of cooling during the same late-Cretaceous to Paleogene low-angle subduction that affected most of western North America. Post-Laramide resumption of subduction continued chilling the western SFA. Small thrust earthquakes at the contact between the Juan de Fuca slab and the SFA indicate that the contact is still relatively cold to depths approaching 90 km. We propose that this chilled lithospheric section as responsible for the block-like integrity of the core of the Sierra Nevada. The Peninsular Ranges in southern California have also maintained a high degree of integrity, at least until recent times, because they shared a similar batholithic generation and Laramide chilling as the Sierra Nevada. The tomographic image includes other large-scale features. West of the SFA is a low-velocity region interpreted as upwelling mantle filling the window behind the NW-translating Juan de Fuca slab. This low-velocity feature appears to be offset by the San Andreas fault, which would indicate transform relations extend into the mantle. Compression and shortening between the Peninsular Ranges and the Sierra Nevada blocks began when the transform boundary shifted east of the Peninsular Ranges and Baja California around 5.5 Ma. High-velocity structures in the upper mantle developed beneath the Transverse Ranges and the Southern Great Valley (SGV) to accommodate crustal shortening. Alternative explanations for the SGV Anomaly are explored by comparing the volume of proximal sources to the volume of the sinking SGV Anomaly. No local source such as convective overturning of Sierran block eclogitic roots seems adequate to provide the volume needed to explain the anomaly as a purely local feature. Surface and subsurface views of the plate margin are complimentary, but consistent, and each contributes to resolving problems not accessible to the other.
The total synthesis of strychnine

Sntvc IININE’ The fearsome polsonouc propertIcs of this notorlou\ wbstancc attracted the attention of XVlth century Europe IO the S~r,,&no~ spec~cs which grow In the rain forests of the Southeast Aslan hrchlpclagos and the Coromandcl Coast of India. and gatned for the seeds and bark of those plants a widespread USC for the cxtermmatmn of rodents. and other undcwablcs. as well as 3 certain vogue In medical practice -now known IO he largely unjustlficd by any u1111ty. The Isolation of the pure alkaloid from the beans of Srr~hno.t JRM~II In I8 IX by Pellctlcr and Caventoua was an event of some hIstorIcAl Importance. In that II provldcd a convlnclng and elegant demonctntmn of the correctness of the then only rcccntly proposed and rcvolutlonary su@esrlon that acid-fixmg substances are produced m the vegetable k1ngdom.t Thus did clrcumstancc early place ready at the hand of any mtcrcstcd chemist an abundant supply of a pure crystalhnc compound whose constltutlon and conctructlon could hardly fall IO CXCIIC curiosity. But organic chemistry. In IIS first hundred years. was scarcely equipped for the attack on co formidable an oblccflve. and apart from the determmation of the correct cmplrlcal formula of the alkaloid. and the discovery of a few simple transformations. no substantial progrcts was made until the commencement of the masslvc mvestlgallons of the present century. Then. o\cr a pcrlod of forty years. one of the greatclasslcsof srructuralorganlcchemlstryu-asconstructcd. lnthat effort, dcscrlbcdln more than IWO hundred and fifty separate commumcatlonc. Robert Robmson played a brllhant and commanding role. and the cxfcnslve bcauttful expcrlmcntal contributions of Hcrmann Leuchs were of defimtlve Imponancc. In 1947. the ta\L was finished.’
The Salpêtrière in the wake of Charcot's death

• After Charcot died in 1893, the students of his immediate circle did not fare well academically in the French medical system. Fatigue and bitterness toward the authoritarian Charcot may have contributed to the change in the scientific and social ambience of the Salpetriere of Paris in the generation after Charcot died. Clearly, however, the faculty were not invested in energetically overturning the system that Charcot had established, and their choice of Fulgence Raymond as Charcot's successor was an effective means of permitting a passive waning in the Salpetriere's magnetic influence in world neurology.
ADOPTION CURVES AND SOCIAL INTERACTIONS

This paper considers the observational implications of social influences on adoption decisions for an environment of perfect foresight adopters. We argue that social influences can produce two observable effects: (1) discontinuities in unconditional adoption curves and (2) pattern reversals in conditional adoption curves, in which earlier adoption is found for one group of actors versus another when fundamentals suggest the reverse ordering should occur; in turn the presence of either of these features can, under weak assumptions, be interpreted as evidence of social influences. As such, these properties are robust implications of social effects. (JEL: C40, D01, O33)
Buoyant Convection in Superposed Metal Foam and Water Layers

Heat transfer measurements for natural convection in superposed metal foam and water layers are reported. Two systems heated at the lower boundary are considered: a water-filled cavity with a foam layer on the heated surface and a water-filled cavity with foam layers on the upper and lower surfaces. The present experiments use open cell copper foams with a nominal porosity of 92%, and the relative thicknesses of the water and foam layers are varied. Steady state Nusselt numbers show that the presence of foam on the boundaries enhances overall heat transfer coefficients over that for the water-only layer. Enhancement of overall Nusselt numbers varies from 12% to 60% depending on Rayleigh number. Sublayer configurations with foam on both heat transfer surfaces are more effective for enhancement than a configuration with foam only on the heated surface.
Galacticus: A Semi-Analytic Model of Galaxy Formation

We describe a new, free and open source semi-analytic model of galaxy formation, GALACTICUS. The GALACTICUS model was designed to be highly modular to facilitate expansion and the exploration of alternative descriptions of key physical ingredients. We detail the GALACTICUS engine for evolving galaxies through a merging hierarchy of dark matter halos and give details of the specific implementations of physics currently available in GALACTICUS. Finally, we show results from an example model that is in reasonably good agreement with several observational datasets. We use this model to explore numerical convergence and to demonstrate the types of information which can be extracted from GALACTICUS.
Mobility where mobility is illegal: internal migration and city growth in the Soviet Union.

This paper examines an important anomaly in the internal migration history of the former Soviet Union (FSU). While many cities were closed in the sense of explicitly limiting growth of city population from migration, it was difficult to assess the effectiveness of these controls. We analyze a sample of 308 Soviet cities to isolate the impact of closure regulations controlling for city size. We find that while there are pervasive patterns of city growth, the rate increasing through the 1960s and declining thereafter, there are also pervasive differences between controlled and uncontrolled cities, the later growing significantly faster in almost all cases, controlling for city size.
Nuclear lamin stiffness is a barrier to 3D-migration, but softness can limit survival

Cell migration through solid tissue often involves large contortions of the nucleus, but biological significance is largely unclear. The nucleoskeletal protein lamin-A varies both within and between cell types and was shown here to contribute to cell sorting and survival in migration through constraining micropores. Lamin-A proved rate-limiting in 3D-migration of diverse human cells that ranged from glioma and adenocarcinoma lines to primary mesenchymal stem cells (MSCs). Stoichiometry of A- to B-type lamins established an activation barrier, with high lamin-A:B producing extruded nuclear shapes post-migration. Because the juxtaposed A, B polymer assemblies respectively conferred viscous and elastic stiffness to the nucleus, sub-populations with different A:B levels sorted in 3D-migration. However, net migration was also biphasic in lamin-A, as wildtype lamin-A levels protected against stress-induced death, whereas deep knockdown caused broad defects in stress-resistance. In vivo xenografts proved consistent with A:B-based cell sorting, and intermediate A:B enhanced tumor growth. Lamins thus impede 3D migration but also promote survival against migration-induced stresses.
Analysis of a quantum nondemolition measurement scheme based on Kerr nonlinearity in photonic crystal waveguides.

We discuss the feasibility of a quantum nondemolition measurement (QND) of photon number based on cross phase modulation due to the Kerr effect in photonic crystal waveguides (PCW’s). In particular, we derive the equations for two modes propagating in PCW’s and their coupling by a third order nonlinearity. The reduced group velocity and small cross-sectional area of the PCW lead to an enhancement of the interaction relative to bulk materials. We show that in principle, such experiments may be feasible with current photonic technologies, although they are limited by material properties. Our analysis of the propagation equations is sufficiently general to be applicable to the study of soliton formation, all-optical switching and can be extended to processes involving other orders of the nonlinearity.
A New, Simple Procedure for the Preparation of 8-Methoxy-2-Tetralone

Abstract 8-Methoxy-2-tetralone (6) can be easily prepared in approximately 50% overall yield starting from 2-bromophenylacetic acid (1), utilizing a Friedel-Crafts acylation/cyclization, ketone protection, copper(I)-catalyzed methoxylation of the aromatic bromide in the presence of an ester as a co-catalyst, and ketone deprotection.