cssi/SciSciGPT-SciSciNet huggingface dataset:
Testing the Internal Consistency of Contingent Valuation Surveys

Abstract For an internal consistency check, one can examine WTP responses to different surveys. Holding an environmental problem constant, concave preferences imply WTPconcavein the success of a remedy. The same preferences imply WTPconvexin the magnitude of an environmental problem, assuming a successful remedy. Having opposite signed curvature of these two WTP patterns is general, not requiring concave preferences. For an adding-up test, an environmental commodity can be divided. Then, WTP for one part plus WTP for the second part, conditional on already having the first part, equals WTP for the whole, adjusted by an income effect.
Extracting the dark matter mass from single stage cascade decays at the LHC

We explore a variant on the M T2 kinematic variable which enables dark matter mass measurements for simple, one stage, cascade decays. This will prove useful for constraining a subset of supersymmetric processes, or a class of leptophilic dark matter models at the LHC. We investigate the statistical reach of these measurements and discuss which sources of error have the largest effects. For example, we find that using only single stage cascade decays with initial state radiation, a measurement of a 150 GeV dark matter candidate can be made to $ \mathcal{O}\left( {10\% } \right) $ for a parent mass of 300 GeV with a production cross section of 100 fb and 100 fb−1 of integrated luminosity provided that backgrounds can be tightly controlled.
An Improved Direct Oxidation of Alkyl Halides to Aldehydes

The oxidation of alkyl chlorides and bromides with dimethyl sulfoxide has been performed in the presence of sodium iodide. This method allows a convenient one-step procedure for the preparation of ...
Synthesis of 2-O-heteroaroyl taxanes: evaluation of microtubule assembly promotion and cytotoxicity

Abstract A series of heterocyclic taxanes were synthesized and evaluated to investigate structure activity relationships at the 2-position of paclitaxel. The compounds were prepared through a regioselective deacylation, reacylation sequence of suitably protected paclitaxel. The heterocyclic substituted diterpenes were synthesized from paclitaxel in four steps in high overall yields. Evaluation of these analogues in a microtubule assembly assay and for their cytotoxicity against B16 melanoma cells illustrated that these compounds had diminished activity compared to paclitaxel.
Posterior immediate implant placement with simultaneous crestal approach maxillary sinus bone graft and flapless extraction

membrane) with a mineralized allograft in combination with a roughened titanium tenting screw placed 3-4 mm below the implant platform, and coronal advancement flap. The hard and soft tissues around the implant were evaluated at 6months and approximately 1 year after treatment. Preand post-operative clinical, cone beam computed tomography (CBCT), and restorative cast measurements were made for all patients. Methods of Data Analysis:Descriptive analysis, such as mean and standard deviation (SD) Results: The mean (SD) of pre-operative crestal (2 mm from crest) and mid-implant buccal bone thickness increased from 0.18 (0.45) mm and 0.64 (0.68) mm to 2.02 (0.88) mm and 2.71 (0.34) mm, respectively, approximately one year after treatment. The mean pre-operative soft tissue thickness [measured at implant platform level on study casts or by using CT scan if casts were not available (2)] increased from 1.53 (0.43) mm to 2.81 (0.45) mm. Further, the average width of the labial keratinized tissue improved, from 2.53 (1.26) mm to 3.82 (1.05) mm, and the mean gingival margin height (measured on soft tissue casts with a digital caliper) increased from 1.64 (0.50) mm to 2.87 (0.28) mm. The mean pre-operative tooth length reduced from 10.89 (1.26) mm to 9.64 (0.84) mm (measured using casts). Conclusions: The use of a mineralized allograft with roughened tenting screws and collagen membrane coverage was effective in improving peri-implant soft tissue around ailing implants with gingival recession.
A technique for treatment of advanced carcinomas of the larynx and hypopharynx using low-megavoltage X-rays.

Summary An isocentric three-field technique is described for irradiation of advanced lesions of the larynx and hypopharynx with low-megavoltage (≤6 MV) X-rays. The technique has been designed to eliminate field junctures. Two anterior oblique fields and a single posterior field with central spinal cord block are used. With Ellis filters to compensate for tissue deficits dose homogeneity is assured throughout the upper and lower neck; in particular, the dose at the anterior aspect of the spinal cord is seen to vary by less than 5%. Using this technique, it is possible to deliver 52 Gy to the primary tumor and regional nodes, while restricting the maximum spinal cord dose to 45 Gy. Computed dose distributions are presented and compared with point-dose thermoluminescent measurements made on a humanoid phantom.
Synthesis of O-Alkyl-3-Dimethylhydrazonothionoesters

Abstract O-Alkyl-3-dimethylhydrazonothionoesters were obtained by the reaction of dimethyl-hydrazones of acetone and acetophenone with S-ethyl-O-alkyldithiocarbonates.
Stereoselective Copper‐Catalyzed Intramolecular Alkene Aminooxygenation: Effects of Substrate and Ligand Structure on Selectivity

A new protocol for diastereoselective copper-catalyzed intra-molecular alkene aminooxygenation, which provides methyleneoxy-functionalized disubstituted pyrrolidines and five-membered cyclic ureas from the corresponding γ-alkenyl sulfonamides and N-allylureas, is reported. In addition, some success was achieved in enantioselective desymmetrizations reactions. We discovered that the level of enantioselectivity and diastereoselectivity could be tuned by choice of copper(II) ligands and substrate N-substituent.
Unitary representability of free abelian topological groups

For every Tikhonov space X the free abelian topological group A(X) and the free locally convex vector space L(X) admit a topologically faithful unitary representation. For compact spaces X this is due to Jorge Galindo.
Comments on Jan Golinski's making natural knowledge

About three lines into his book Making Natural Knowledge , Jan Golinski defines the “constructivist” view of science as “that which regards scientific knowledge primarily as a human product, made with locally situated cultural and material resources, rather than as simply the revelation of a pre-given order of nature” (Golinski 1998, p. ix). Having a pretty good idea of what Professor Golinski's book was going to be about, this stopped me for a moment. Is that all there is to it? Is that what the work of the Strong Programme, Latour, Pickering, Knorr-Cetina; the talk of mangle, black boxes and resistances, is all about? Described this way, it seems quite reasonable; a way of thinking about scientific activity that should at least be given a hearing. Admittedly, I have seen other, usually more prolix, ways of characterizing what Golinski has called the constructivist view of science. But I like this one. It sends what I believe to be the correct message that this “constructivism” is, at its heart, better characterized as plausible and intriguing than outrageous, and that it is not necessarily threatening to any core values held by historians.
P.R.E.S.S. — AN R-PACKAGE FOR EXPLORING RESIDUAL-LEVEL PROTEIN STRUCTURAL STATISTICS

P.R.E.S.S. is an R-package developed to allow researchers to get access to and manipulate a large set of statistical data on protein residue-level structural properties such as residue-level virtual bond lengths, virtual bond angles, and virtual torsion angles. A large set of high-resolution protein structures is downloaded and surveyed. Their residue-level structural properties are calculated and documented. The statistical distributions and correlations of these properties can be queried and displayed. Tools are also provided for modeling and analyzing a given structure in terms of its residue-level structural properties. In particular, new tools for computing residue-level statistical potentials and displaying residue-level Ramachandran-like plots are developed for structural analysis and refinement. P.R.E.S.S. has been released in R as an open source software package, with a user-friendly GUI, accessible and executable by a public user in any R environment. P.R.E.S.S. can also be downloaded directly at http://www.math.iastate.edu/press/.
An embedded genus-one helicoid

There exists a properly embedded minimal surface of genus one with one end. The end is asymptotic to the end of the helicoid. This genus one helicoid is constructed as the limit of a continuous one-parameter family of screw-motion invariant minimal surfaces―also asymptotic to the helicoid―that have genus equal to one in the quotient.
The Effects of Motive Information and Crime Unusualness on Jurors' Judgments in Insanity Cases

This study investigated the effects of motive information and crime unusualness on mock jurors' judgments in two homicide cases in which the defendant pleaded insanity. Undergraduates (N = 371) read case information and rendered a verdict, estimated the probability that the defendant was insane, and made additional judgments about the defendant's mental state. The defendant was more likely to be judged insane if the crime was oddly committed rather than committed in a typical manner. Prosecution motive information also affected judgments; the defendant was considered more sane if the prosecution presented evidence of a strong, reasonable motive. Evidence of a “crazy,” unreasonable motive, presented by the defense, caused jurors to see the defendant in one of the cases as more insane.
Centrally symmetric polytopes with many faces

We present explicit constructions of centrally symmetric polytopes with many faces: (1) we construct a d-dimensional centrally symmetric polytope P with about 3d/4 ≈ (1.316)d vertices such that every pair of non-antipodal vertices of P spans an edge of P, (2) for an integer k ≥ 2, we construct a d-dimensional centrally symmetric polytope P of an arbitrarily high dimension d and with an arbitrarily large number N of vertices such that for some 0 0, we construct a centrally symmetric polytope Q with an arbitrarily large number of vertices N and of dimension d = k1+o(1) such that at least \((1 - k^{ - \alpha } )(_k^N )\)k-subsets of the set of vertices span faces of Q.
Classical curves via one-vertex maps

One-vertex maps (a type of dessin d’enfant) give a uniform characterization of certain well-known algebraic curves, including those of Klein, Wiman, Accola–Maclachlan and Kulkarni. The characterization depends on a new classification of one-vertex (dually, one-face or unicellular) maps according to the size of the group of map automorphisms. We use an equivalence relation appropriate for studying the faithful action of the absolute Galois group on dessins, although we do not pursue that line of inquiry here.
Moduli in N = 1 heterotic/F-theory duality

Abstract The moduli in a 4D N = 1 heterotic compactification on an elliptic CY, as well as in the dual F-theoretic compactification, break into “base” parameters which are even (under the natural involution of the elliptic curves), and “fiber” or twisting parameters; the latter include a continuous part which is odd, as well as a discrete part. We interpret all the heterotic moduli in terms of cohomology groups of the spectral covers, and identify them with the corresponding F-theoretic moduli in a certain stable degeneration. The argument is based on the comparison of three geometric objects: the spectral and cameral covers and the ADE del Pezzo fibrations. For the continuous part of the twisting moduli, this amounts to an isomorphism between certain abelian varieties: the connected component of the heterotic Prym variety (a modified Jacobian) and the F-theoretic intermediate Jacobian. The comparison of the discrete part generalizes the matching of heterotic 5-brane/F-theoretic 3-brane impurities.
Coalescence and Meeting Times on n-Block Markov Chains

We consider finite-state, discrete-time, mixing Markov chains \((V,P)\), where \(V\) is the state space and \(P\) is the transition matrix. To each such chain \((V,P)\), we associate a sequence of chains \((V_n,P_n)\) by coding trajectories of \((V,P)\) according to their overlapping \(n\)-blocks. The chain \((V_n,P_n)\), called the \(n\)-block Markov chain associated with \((V,P)\), may be considered an alternate version of \((V,P)\) having memory of length \(n\). Along such a sequence of chains, we characterize the asymptotic behavior of coalescence times and meeting times as \(n\) tends to infinity. In particular, we define an algebraic quantity \(L(V,P)\) depending only on \((V,P)\), and we show that if the coalescence time on \((V_n,P_n)\) is denoted by \(C_n\), then the quantity \(\frac{1}{n} \log C_n\) converges in probability to \(L(V,P)\) with exponential rate. Furthermore, we fully characterize the relationship between \(L(V,P)\) and the entropy of \((V,P)\).
Sub-Nanosecond Time of Flight on Commercial Wi-Fi Cards

The time-of-flight of a signal captures the time it takes to propagate from a transmitter to a receiver. Time-of-flight is perhaps the most intuitive method for localization using wireless signals. If one can accurately measure the time-of-flight from a transmitter, one can compute the transmitter's distance simply by multiplying the time-of-flight by the speed of light. Today, GPS, the most widely used outdoor localization system, localizes a device using the time-of-flight of radio signals from satellites. However, applying the same concept to indoor localization has proven difficult. Systems for localization in indoor spaces are expected to deliver high accuracy (e.g., a meter or less) using consumer-oriented technologies (e.g., Wi-Fi on one's cellphone). Unfortunately, past work could not measure time-of-flight at such an accuracy on Wi-Fi devices. As a result, over the years, research on accurate indoor positioning has moved towards more complex alternatives such as employing large multi-antenna arrays to compute the angle-of-arrival of the signal. These new techniques have delivered highly accurate indoor localization systems. Despite these advances, time-of-flight based localization has some of the basic desirable features that state-of-the-art indoor localization systems lack. In particular, measuring time-of-flight does not require more than a single antenna on the receiver. In fact, by measuring time-of-flight of a signal to just two antennas, a receiver can intersect the corresponding distances to locate its source. Thus, a receiver can locate a wireless transmitter with no support from the surrounding infrastructure. This is quite unlike current indoor localization systems, which require multiple access points at known locations, to find the distance between a pair of mobile devices. Furthermore, each of these access points need to have many antennas -- far beyond what is supported in commercial Wi-Fi devices. In this demo, we will present Chronos, a system that combines a set of novel algorithms to measure the time-of-flight to sub-nanosecond accuracy on commercial Wi-Fi cards. In particular, we will measure distance/time-of-flight between two devices equipped with commercial Wi-Fi cards, without any support from the infrastructure or environment fingerprinting.
Orbital dynamics for rigid bodies

In this paper I describe a method for calculating the motions of a collection of self-gravitating rigid bodies. The bodies are described by polyhedra of general shapes with triangular faces. The gravitational potential of such objects can be calculated via the ‘polyhedron gravity’ routines of Werner (1994) and Werner and Scheeres (1996), and the resulting mutual forces and torques calculated via surface integration. Additional components of the overall scheme include updating the spin vector and orientation of the bodies, and their positions, velocities, and angular momenta after each timestep. Collisions are allowed, and treated via the impulse approximation. Inelastic or frictional collisions can be handled via coefficients of restitution. After the description of the scheme, I present some results that verify global conservation of momentum and energy during sample calculations.
Anomalous Band Gap Behavior in Mixed Sn and Pb Perovskites Enables Broadening of Absorption Spectrum in Solar Cells

Perovskite-based solar cells have recently been catapulted to the cutting edge of thin-film photovoltaic research and development because of their promise for high-power conversion efficiencies and ease of fabrication. Two types of generic perovskites compounds have been used in cell fabrication: either Pb- or Sn-based. Here, we describe the performance of perovskite solar cells based on alloyed perovskite solid solutions of methylammonium tin iodide and its lead analogue (CH3NH3Sn1–xPbxI3). We exploit the fact that, the energy band gaps of the mixed Pb/Sn compounds do not follow a linear trend (the Vegard’s law) in between these two extremes of 1.55 and 1.35 eV, respectively, but have narrower bandgap (<1.3 eV), thus extending the light absorption into the near-infrared (∼1,050 nm). A series of solution-processed solid-state photovoltaic devices using a mixture of organic spiro-OMeTAD/lithium bis(trifluoromethylsulfonyl)imide/pyridinium additives as hole transport layer were fabricated and studied as a f...
Performance of radiation hard CCDs as tracking devices

Abstract We present data on the operation of radiation hard CCDs used as tracking devices. The system consisted of 5 Texas Instruments CCDs with a total number of cells equal to 2.7 × 106. The tracking resolution for minimum ionizing particles was measured to be σx = 4.8 ± 0.2 μm and σy = 5.0 ± 0.3 μm. Two track separation of better than 40 μm in space was also obtained.
IID: independently and indistinguishably distributed

Abstract The inability of the Bayesian model to accommodate Ellsberg-type behavior is well-known. This paper focuses on another limitation of the Bayesian model, specific to a dynamic setting, namely the inability to permit a distinction between experiments that are identical and those that are only indistinguishable. It is shown that such a distinction is afforded by recursive multiple-priors utility. Two related technical contributions are the proof of a strong LLN for recursive multiple-priors utility and the extension to sets of priors of the notion of regularity of a probability measure.
The Effect of Hospital Mergers on Inpatient Prices: A Case Study of the New Hanover–Cape Fear Transaction

Abstract The Federal Trade Commission initiated a Hospital Merger Retrospective Project in 2002 to analyze the effects of consummated mergers. One of the mergers studied was the 1998 acquisition by New Hanover Regional Medical Center (“New Hanover”) of Columbia Cape Fear Memorial Hospital (“Cape Fear”) in Wilmington, North Carolina. In this paper, we employ patient‐level claims data from four different insurers to estimate the effects of this merger on inpatient prices. Our results provide mixed evidence. Two of the insurers experienced substantial post‐merger price increases relative to the control group of hospitals. The post‐merger price changes for another insurer, however, were comparable to those for the control group, while the fourth insurer actually experienced a significant price decrease following the merger. Thus it is difficult to draw conclusions about the impact of this merger on inpatient pricing.
Mirror symmetries for brane configurations and branes at singularities

Abstract We study local mirror symmetry on non-compact Calabi–Yau manifolds (conifold type of singularities) in the presence of D3 brane probes. Using an intermediate brane setup of NS 5-branes `probed' by D-branes, we can explicitly T-dualize three isometry directions to relate a non-compact Calabi–Yau manifold to its local mirror. Both intervals and boxes of NS 5-branes appear as brane setups. Going from one to the other is equivalent to performing a conifold transition in the dual geometry. One result of our investigation is that the brane box constructions, as they have been discussed so far, should be modified.
Multilayer modeling of radiative transfer by SLW and CW methods in non-isothermal gaseous medium

Non-isothermal gaseous medium is modeled using the multilayer approach, breaking the one-dimensional system into a series of isothermal layers. Spectral integration of the radiative transfer equation (RTE) is performed for the spectral line weighted-sum-of-gray-gases and cumulative wavenumber approaches to modeling the spectral nature of the gas radiation. An exact analytical solution of RTE is obtained for the layers with both black and gray walls. Predictions show high accuracy, even with surprisingly few layers.
The structure of naphthalene

Abstract The structure of naphthalene has been determined by ab initio gradient computation at the Hartree—Fock level using the 4–21 basis set. Special attention is paid to the small differences between the nearly equal C-C distances and to evaluation of the ability of electron diffraction experiments to distinguish among them. The computed orbital energies are used to assign the photoelectron spectrum.
On the Conditions to Extend Ricci Flow

Consider {(M n , g(t)), 0 ⩽ t < T < ∞} as an unnormalized Ricci flow solution: for t ∈ [0, T). Richard Hamilton shows that if the curvature operator is uniformly bounded under the flow for all t ∈ [0, T) then the solution can be extended over T. Natasa Sesum proves that a uniform bound of Ricci tensor is enough to extend the flow. We show that if Ricci is bounded from below, then a scalar curvature integral bound is enough to extend flow, and this integral bound condition is optimal in some sense.
FeCl3-Catalyzed Tandem Prins and Friedel-Crafts Cyclization: A Highly Diastereoselective Route to Polycyclic Ring Structures.

Abstract Catalytic FeCl 3 in the presence of 4 A molecular sieves has been shown to effect highly diastereoselective tandem Prins and Friedel–Crafts cyclization of substituted ( E / Z )-6-phenylhex-3-en-1-ol and a variety of aldehydes to provide a range of polycyclic compounds in good to excellent yields. The reaction of an enantioenriched alcohol with an aldehyde provided the cyclization product without loss of optical activity. Furthermore, a Lewis acid catalyzed ring opening resulted in functionalized tetralin derivatives with multiple chiral centers.
Perelman’s Entropy and Doubling Property on Riemannian Manifolds

The purpose of this work is to study some monotone functionals of the heat kernel on a complete Riemannian manifold with nonnegative Ricci curvature. In particular, we show that on these manifolds, the gradient estimate of Li and Yau (Acta Math. 156, 153–201, 1986), the gradient estimate of Ni (J. Geom. Anal. 14(1), 87–100, 2004), the monotonicity of the Perelman’s entropy and the volume doubling property are all consequences of an entropy inequality recently discovered by Baudoin and Garofalo, arXiv:0904.1623 , 2009. The latter is a linearized version of a logarithmic Sobolev inequality that is due to D. Bakry and M. Ledoux (Rev. Mat. Iberoam. 22, 683–702, 2006).
Oligosaccharide synthesis with glycosyl phosphate and dithiophosphate triesters as glycosylating Agents

Described is an efficient one-pot synthesis of alpha- and beta-glycosyl phosphate and dithiophosphate triesters from glycals via 1,2-anhydrosugars. Glycosyl phosphates function as versatile glycosylating agents for the synthesis of beta-glucosidic, beta-galactosidic, alpha-fucosidic, alpha-mannosidic, beta-glucuronic acid, and beta-glucosamine linkages upon activation with trimethylsilyl trifluoromethanesulfonate (TMSOTf). In addition to serving as efficient donors for O-glycosylations, glycosyl phosphates are effective in the preparation of S-glycosides and C-glycosides. Furthermore, the acid-catalyzed coupling of glycosyl phosphates with silylated acceptors is also discussed. Glycosyl dithiophosphates are synthesized and are also used as glycosyl donors. This alternate method offers compatibility with acceptors containing glycals to form beta-glycosides. To minimize protecting group manipulations, orthogonal and regioselective glycosylation strategies with glycosyl phosphates are reported. An orthogonal glycosylation method involving the activation of a glycosyl phosphate donor in the presence of a thioglycoside acceptor is described, as is an acceptor-mediated regioselective glycosylation strategy. Additionally, a unique glycosylation strategy exploiting the difference in reactivity of alpha- and beta-glycosyl phosphates is disclosed. The procedures outlined here provide the basis for the assembly of complex oligosaccharides in solution and by automated solid-phase synthesis with glycosyl phosphate building blocks exclusively or in concert with other donors.
Semiconductor detector performance for low-energy X-rays

Abstract Factors that limit the capabilities of semiconductor detectors at photon energies below 5 keV include energy resolution, detector efficiency, and detector-related continuum background. These properties can be controlled to a certain extent by optimal detector design and fabrication techniques. We describe measurements on the low energy response of Si(Li) detectors obtained using a tunable monochromatic source. Window thicknesses have been measured for a number of devices using different materials for the entry contact. The interpretation of these results in terms of existing detector window models is discussed. Results obtained using a new contact structure demonstrate that a dramatic reduction in window-related absorption in Si(Li) detectors can be achieved.
Molecular Structures and Reactivity of Supported Molybdenum Oxide Catalysts

Supported molybdenum oxide catalysts were prepared by an equilibrium adsorption method. The molecular structures of the molybdenum oxide overlayers on different oxide supports (Al{sub 2}O{sub 3}, TiO{sub 2}, ZrO{sub 2}, SiO{sub 2}, and MgO), under in situ conditions, were investigated by Raman spectroscopy. The molybdenum oxide species on TiO{sub 2}, ZrO{sub 2}, and Al{sub 2}O{sub 3} possess a highly distorted, octahedrally coordinated surface molybdenum oxide species with one short Mo=O bond regardless of the molybdenum oxide content. The MoO{sub 3}/SiO{sub 2} catalysts primarily contain crystalline MoO{sub 3} because of the lower density and reactivity of the silica surface OH groups. The MoO{sub 3}/MgO catalysts possess MgMoO{sub 4} and CaMoO{sub 4} compounds due to the high aqueous solubility of MgO and CaO (an impurity in the MgO support) and the strong acid-base interaction between molybdenum oxide and MgO/CaO. The methanol oxidation reaction studies revealed that the MoO{sub 3}/TiO{sub 2} (anatase and rutile) and MOO{sub 3}/ZrO{sub 2} catalysts are the most active catalysts and that their activities (TOFs) are at least 1-2 orders of magnitude higher than those of the MoO{sub 3}/Al{sub 2}O{sub 3}, MoO{sub 3}SiO{sub 2}, and MoO{sub 3}/MgO catalysts. It was also found that the catalytic activities correlate with themore » reducibility of the surface molybdenum oxide species on the oxide supports as well as their surface morphology (e.g., molybdenum oxide dispersion and molybdate compound formation). These studies demonstrate that the specific oxide support controls the reactivity of the supported molybdenum oxide phases. 55 refs., 6 figs., 2 tabs.« less
A Comprehensive History of Arynes in Natural Product Total Synthesis

Within 14 years of the seminal experiments of J. D. Roberts leading to the first proposal of the structure of benzyne (1), synthetic organic chemists recognized the potential to exploit this highly reactive intermediate (and its substituted variants) in the total synthesis of natural products. More specifically, it was recognized that arynes offered the strategic advantage of rapidly functionalizing an aromatic ring by forming multiple carbon− carbon or carbon−heteroatom bonds in a single operation, often in a regioselective manner. Initially, the scope of synthetic applications was somewhat limited by the harsh conditions required to produce the aryne species. Many of these methods required strong bases, such as n-BuLi, or high temperatures (Scheme 1). However, with the development of milder methods for the generation of arynes came increased interest in employing them in the synthesis of more complex polycyclic systems. Most recently, the use of o-silyl aryl triflates as aryne precursors has allowed generation of the reactive intermediate under almost neutral conditions. To date, over 75 individual natural products have been prepared using arynes to generate key synthetic intermediates. Herein are recounted the reports of total syntheses that utilize arynes in ways that build complexity or introduce motifs essential to the completion of their targets. The methods by which the authors featured in this review accomplish this task reflect the versatility of arynes as reactive intermediates for synthesis (Scheme 2). For the purposes of organization, the syntheses are divided into subgroups on the basis of the type of aryne transformation: (i) nucleophilic additions or multicomponent reactions, (ii) σ-bond insertion reactions, (iii) [4 + 2]- and [2 + 2]-cycloaddition strategies, and (iv) metal-catalyzed aryne reactions.
Measuring the rate of intramolecular contact formation in polypeptides

Formation of a specific contact between two residues of a polypeptide chain is an important elementary process in protein folding. Here we describe a method for studying contact formation between tryptophan and cysteine based on measurements of the lifetime of the tryptophan triplet state. With tryptophan at one end of a flexible peptide and cysteine at the other, the triplet decay rate is identical to the rate of quenching by cysteine. We show that this rate is also close to the diffusion-limited rate of contact formation. The length dependence of this end-to-end contact rate was studied in a series of Cys-(Ala-Gly-Gln)k-Trp peptides, with k varying from 1 to 6. The rate decreases from ∼1/(40 ns) for k = 1 to ∼1/(140 ns) for k = 6, approaching the length dependence expected for a random coil (n−3/2) for the longest peptides.
The exploratory far-UV photochemistry of 1-methyl-1-silabicyclo[2.2.1]hept-2-ene and 2-trimethylsilylbicyclo[2.2.1]hept-2-ene

Abstract 1-Methyl-1-silabicyclo[2.2.1]hept-2-ene was synthesized in 27% yield by chloramine-T oxidation of mixture of C-2/C-3 phenylselenide derivatives of 1-methyl-1-silabicyclo[2.2.1]heptane. The phenylselenides in turn were produced in 8% yield by GifIII oxidation of 1-methyl-1-silabicyclo[2.2.1]heptane. The 214 nm photolysis of the rigid 1-silanorbornene in MeOH or (CH3)3COH resulted in [1,3-C] migration to afford 3-alkoxy-3-methyl-3-silabicyclo[4.1.0]heptanes with quantum yields of 0.053 (methoxy derivative) and 0.062 (tert-butoxy derivative). The efficiency for photoprotonation was estimated to be f
Molecular aggregation and its applicability to synthesis. The Diels-Alder reaction

Abstract The rates of intermolecular Diels-Alder reactions involving relatively hydrophobic dienes and dienophiles are significantly increased if these reactions are carried out in ethylene glycol. These rate enhancements are most easily understood in terms of aggregation phenomena.
An Analysis of the War of Attrition and the All-Pay Auction

We study the war of attrition and the all-pay auction when players’ signals are affiliated and symmetrically distributed. We (a) find sufficient conditions for the existence of symmetric monotonic equilibrium bidding strategies and (b) examine the performance of these auction forms in terms of the expected revenue accruing to the seller. Under our conditions the war of attrition raises greater expected revenue than all other known sealed-bid auction forms. Journal of Economic Literature Classification Numbers: D44, D82. 1997 Academic Press
The rhetoric of policy relevance in international economics

This paper addresses the link between the generation of economic knowledge and economic policy conclusions. Focusing on the case of research in international trade, It establishes a taxonomy of rhetorical practices used to make such a link. The flexibility observed in these practices contrasts markedly with the rigidity of the conventions of theoretical and empirical knowledge creation. A survey of articles on international trade from four major journals from 1988 to 1992 shows that most policy-relevant research is entirely theoretical, but the incidence of rhetorical practices legitimating policy conclusions depends on the nature of the research method (theoretical or empirical), and the journal in which the research is published. The survey data support the conclusion that the flexibility of rhetorical practices is integral to the legitimation of the knowledge generated by international trade economists.
Long-Lag, Wide-Pulse Gamma-Ray Bursts

The best available probe of the early phase of gamma-ray burst (GRB) jet attributes is the prompt gamma-ray emission, in which several intrinsic and extrinsic variables determine observed GRB pulse evolution, including at least: jet opening angle, profiles of Lorentz factor and matter/field density, distance of emission region from central source, and viewing angle. Bright, usually complex bursts have many narrow pulses that are difficult to model due to overlap. However, the relatively simple, long spectral lag, wide-pulse bursts may have simpler physics and are easier to model. We have analyzed the temporal and spectral behavior of wide pulses in 24 long-lag bursts from the BATSE sample, using a pulse model with two shape parameters - width and asymmetry - and the Band spectral model with three shape parameters. We find that pulses in long-lag bursts are distinguished both temporally and spectrally from those in bright bursts: the pulses in long spectral lag bursts are few in number, and approximately 100 times wider (10s of seconds), have systemtically lower peaks in nu*F(nu), harder low-energy spectra and softer high-energy spectra. These five pulse descriptors are essentially uncorrelated for our long-lag sample, suggesting that at least approximately 5 parameters are needed to model burst temporal and spectral behavior, roughly commensurate with the theoretical phase space. However, we do find that pulse width is strongly correlated with spectral lag; hence these two parameters may be viewed as mutual surrogates. The prevalence of long-lag bursts near the BATSE trigger threshold, their predominantly low nu*F(nu) spectral peaks, and relatively steep upper power-law spectral indices indicate that Swiift will detect many such bursts.
Algebraic radicals and incidence algebras

If I (X, R) denotes the incidence algebra of the locally finite partially ordered set X over the ring with identity R, the upper and lower nil radicals of I (X, R) are described using the strong product property. An application of this information in the determination of algebraic radicals in the case when R is an algebra over a field is then given.
The PI3K/Akt Pathway Mediates the Nongenomic Cardioprotective Effects of Estrogen Following Trauma-hemorrhage

Objective:To determine whether the nongenomic actions of E2 have any beneficial effect on cardiac function following trauma-hemorrhage and whether those effects are mediated via the PI3K/Akt pathway.Summary Background Data:Since studies suggest that both genomic and nongenomic pathways are involved
Causality and Chance in Relativistic Quantum Field Theories

Bell appealed to the theory of relativity in formulating his principle of local causality. But he maintained that quantum field theories do not conform to that principle, even when their field equations are relativistically covariant and their observable algebras satisfy a relativistically motivated microcausality condition. A pragmatist view of quantum theory and an interventionist approach to causation prompt the reevaluation of local causality and microcausality. Local causality cannot be understood as a reasonable requirement on relativistic quantum field theories: it is unmotivated even if applicable to them. But microcausality emerges as a sufficient condition for the consistent application of a relativistic quantum field theory.
Warped cones and property A

We describe a construction (the ‘warped cone construction’) which produces examples of coarse spaces with large groups of translations. We show that by this construction we can obtain many examples of coarse spaces which do not have property A or which are not uniformly embeddable into Hilbert space.
Formation of cyclopropanes by homolytic substitution reactions of 3- iodopropyl radicals: Preparative and rate studies

Abstract Reduction of 2-substituted 1,3-diiodopropane derivatives with tin hydride provides substituted cyclopropanes. The reaction occurs through a homolytic substitution of the 3-iodopropyl radical, which has a rate constant of about 5 × 105s−1 at 80°C.
Angle-Resolved Photoemission Spectra of Graphene from First-Principles Calculations

Angle-resolved photoemission spectroscopy (ARPES) is a powerful experimental technique for directly probing electron dynamics in solids. The energy versus momentum dispersion relations and the associated spectral broadenings measured by ARPES provide a wealth of information on quantum many-body interaction effects. In particular, ARPES allows studies of the Coulomb interaction among electrons (electron-electron interactions) and the interaction between electrons and lattice vibrations (electron-phonon interactions). Here, we report ab initio simulations of the ARPES spectra of graphene including both electron-electron and electron-phonon interactions on the same footing. Our calculations reproduce some of the key experimental observations related to many-body effects, including the indication of a mismatch between the upper and lower halves of the Dirac cone.
Cissampentin: A new bisbenzylisoquinoline alkaloid from Cissampelos fasciculata

A new bisbenzylisoquinoline alkaloid, cissampentin, has been isolated from the aerial parts of Cissampelos fasciculata. Detailed interpretation of various spectra allowed identification of most structural features, including a rare methyleneoxy bridge. Although attempted methylation of this alkaloid led to complex mixtures, reaction with diethyl phosphorochloridate gave a single diethyl phosphate derivative and allowed assignment of a 7′-11 ether linkage. Bioassays indicate significant activity as a repellent to the leafcutter and Acromyrmex octospinosus, and limited antifungal activity.
Existence of Atoms and Molecules in Non-Relativistic Quantum Electrodynamics

We show that the Hamiltonian describing N nonrelativistic electrons with spin, interacting with the quantized radiation field and several fixed nuclei with total charge Z, has a ground state when N < Z + 1. The result holds for any value of the fine structure constant α and for any value of the ultraviolet cutoff A on the radiation field. There is no infrared cutoff. The basic mathematical ingredient in our proof is a novel localization of the electromagnetic field in such a way that the errors in the energy are of smaller order than 1/L, where L is the localization radius.
Radar cross section measurements

The progress in radar cross section measurements is strongly related to the progress in radar technology. The recent acceleration in radar technology and processing techniques has generated a corresponding acceleration in interest for radar cross section measurements. Historically, early radar cross section measurements were performed to determine the detection range of radar systems, a fundamental objective that still exists. Later measurements, coupled with analytic techniques and computer codes, were performed to extend our understanding of the radar scattering process. At the present time, the availability of broad-band electronics, signal processing techniques, and digital technology results in radar cross section measurement programs which are directed toward exploring the performance of operational waveforms and processing, target discrimination, target detectability in clutter, and radar scattering control. The fundamentals of radar cross section measurements are reviewed. Measurement facilities, including the present research activities on compact range techniques, are then described. Instrumentation radars have benefited from both wide-bandwidth electronics and digital processing capabilities; Fourier transform techniques, in particular, provide both additional information on target scattering, and increase measurement accuracy by isolating the target from radar returns from the measurement facility. The frequency coverage has also extended to include millimeter-wave frequencies. Achievable accuracy is important in any measurement program, and those factors that limit the accuracy of radar cross section measurements are discussed.
Heat Sterilizable Propellants for Planetary Missions

Dry-heat sterilization, a requirement of all planetary lander missions, places severe requirements on solid rocket propellants that will be used on them. In an ongoing program, which has a goal of producing heat Sterilizable motors with 130 kg of propellant, numerous insights into the problems associated with developing dry-heat Sterilizable propellants have been gained. The one most significant means of increasing propellant stability at sterilization temperature (125°C) is to decrease the ammonium perchlorate (AP) particle size. One possible explanation is that some of the AP crystals larger than 250 n in diameter are unstable at sterilization temperature. Another important findings is the effect grain diameter has on survivability at sterilization temperature. As the grain diameter increases, the time to failure decreases. This is probably due to the increased stress that results from the thermal gradients, which occur during grain heat up or cool down. In this work, 7cm-diam grains have been made that survived 70 sterilization cycles (the requirement is eight); however, 71-cmdiam grains from the same propellant batch have survived only seven cycles.
Statistical model of heavy-ion fusion-fission reactions

Cross-section and neutron-emission data from heavy-ion fusion-fission reactions are consistent with the fission of fully equilibrated systems with fission lifetime estimates obtained via a Kramers-modified statistical model that takes into account the classical collective motion of the system about the ground state, the temperature dependence of the location and height of fission transition points, and the orientation degree of freedom. If the ``standard'' techniques for calculating fission lifetimes are used, then the calculated excitation-energy dependence of fission lifetimes is incorrect. We see no evidence to suggest that the nuclear viscosity has a temperature dependence. The strong increase in the nuclear viscosity above a temperature of $~1.3$ MeV deduced by others is an artifact generated by an inadequate fission model.
Convenient Preparation of Diethyl (2‐Thienyl)methanephosphonate

Abstract This article describes a convenient preparation of diethyl (2‐thienyl)methanephosphonate in 88% overall yield.
Total Synthesis of Michellamines A−C, Korupensamines A−D, and Ancistrobrevine B

Efficient syntheses of the title compounds have been developed. Several strategies for preparation of each of the naphthalene and tetrahydroisoquinoline (THIQ) portions were developed. Initial attempts to use benzyne plus furan cycloaddition reactions were thwarted by the unfavorable sense of the regiochemical outcome. An interesting annulation reaction of benzynes derived from 2,4-dibromophenol derivatives formed the core of the shortest naphthalene synthesis. An alternative annulation initiated by the addition of a benzylic sulfone anion to methyl crotonate led to an efficient naphthol synthesis amenable to large scale. The THIQ synthesis of Bringmann was used initially and subsequently complemented by a route whose key step involved the opening of N-tosyl-2-methylethyleneimine by a 3,5-dimethoxyphenylcuprate reagent. The results from a variety of aryl cross-coupling reactions are described. Suzuki coupling of the boronic acid derived from the naphthalene moiety with a THIQ-iodide was the most generally...
The Optimal Shape of a Javelin

The problem of finding the optimal tapering of a free (nonsupported) javelin is described and solved. For the optimal javelin, the lowest mode of vibration has the highest possible frequency. With this tapering inner damping will lead to the cessation of the vibration at the fastest possible rate. The javelin is modeled as a beam of uniform material. The differential equations governing the vibration and the tapering of the beam are derived. These equations have a difficult singularity at the tips of the beam. A procedure using a similarity solution, as in [1], is used to solve this singular system, and the solution is found. The maximal frequency is found to be almost five times larger than the frequency of a cylindrical rod.
The Guaranteed Gamma-Ray Background

The diffuse extragalactic gamma-ray background (EGRB) above 100 MeV encodes unique information about high-energy processes in the universe. Numerous sources for the EGRB have been proposed, but the two systems that are certain to make some contribution are active galaxies (blazars) as well as normal galaxies. In this Letter we evaluate the contribution to the background from both sources. The active galaxy contribution arises from unresolved blazars. We compute this contribution using the Stecker-Salamon model. For normal galaxies, the emission is due to cosmic-ray interactions with diffuse gas. Our key assumption here is that the cosmic-ray flux in a galaxy is proportional to the supernova rate and thus the massive star formation rate, quantified observationally by the cosmic star formation rate (CSFR). In addition, the existence of stars today requires a considerably higher interstellar medium mass in the past. Using the CSFR to compute both these effects, we find that normal galaxies are responsible for a significant portion (~) of the EGRB near 1 GeV but make a smaller contribution at other energies. Finally, we present a "minimal" two-component model that includes contributions from both normal galaxies and blazars. We show that the spectrum of the diffuse radiation is a key constraint on this model: while neither the blazar spectra nor the galactic spectra are separately optimal fits to the observed spectrum, the combined emission provides an excellent fit. We close by noting key observational tests of this two-component model, which can be probed by future gamma-ray observatories, such as the Gamma-ray Large Area Space Telescope.
An overview of fault-tolerant digital system architecture

With the increasing use of computing systems in such crucial areas as medicine and space, there has come a great need for computers that remain operational in spite of hardware failures. This paper provides a brief overview of several approaches to fault-tolerant computing. Five hardware redundancy techniques are reviewed: static, dynamic, hybrid, self-purging and the reconfiguration scheme. In addition, the advantages and disadvantages of error correcting codes and software fault-tolerant systems are outlined as well as bi-duplexed systems, alternating logic, fail-soft and shared logic systems. It is suggested that perhaps the best fault-tolerant system employ a combination of hardware redundant techniques and software protection.