cssi/SciSciGPT-SciSciNet huggingface dataset:
Maya Blue: An Unsolved Problem in Ancient Pigments

The early peoples of Southern Mexico decorated pottery and painted pictures on walls with a stable blue pigment which is not found elsewhere in the world. Investigation of this blue was started over 30 years ago, but still the true nature of the blue color principle is unknown. Since the blue cannot be destroyed by boiling nitric acid, it does not seem to be vegetable or organic in origin. It is quite unlike azurite or natural ultramarine or other blue minerals which were employed as sources of blue pigment by other ancient peoples. The main obstacle in the investigation is the extreme scarcity of research material. The only samples of the blue available for testing are thinly painted films on potsherds and on wall painting fragments where it is mixed with lime plaster and other impurities. Although attempts to procure lump specimens of the blue, even in gram quantitives, have failed, some progress has been made. It is now known that the inorganic base of the blue pigment is a clay mineral called attapulgite. Ordinary attapulgite is nearly colorless. We still do not know what makes the clay blue; whether it is a special kind of attapulgite or if the Maya produced it artifically. In this paper all the evidence accumulated to date is reviewed. Spectrographic and x-ray diffraction data for Maya blue are tabulated. (See also >I.I.C. Abstracts, 3458).
Isolation of linear peptides related to the hepatotoxins nodularin and microcystins

Abstract Linear peptide 2 , Adda-D-Glu(γ)-Mdhb-D-MeAsp(β)-L-Arg-OH, was isolated from cultured Nodularia spumigena and was analyzed in the cells after one week's ( 1:2 : 30:1) to eight week's (>100:1) cultivation. Three linear peptides, Adda-D-Glu(γ)-Mdha-D-Ala-L-Leu-D-MeAsp(β)-L-Arg-OH ( 3 ), L-Leu-D-MeAsp(β)-L-Arg-Adda-D-Glu(γ)-Mdha-D-Ala-OH ( 4 ), and L-Phe-D-MeAsp(β)-L-Arg-Adda-D-Glu(γ)-Mdha-D-Ala-OH ( 5 ) were obtained from a water bloom of Microcystis spp. collected from Homer Lake (Illinois). Some of these linear peptides ( 2 , 3 ) are thought to be biogenetic precursors of nodularin and microcystins. Linear peptides 2 , 3 , and 4 did not show apparent toxicity at 1.0, 1.1, and 2.25 mg/kg, respectively, in a mouse bioassay (ip). Feeding experiments using 13 C-labeled precursors established that the 2-, 6- and 8-methyl and 9-methoxy carbons of the unusual (2 S ,3 S ,8 S ,9 S )-3-amino-9-methoxy-2,6,8-trimethyl-10-phenyl-4,6-decadienoic acid (Adda) unit of 1 were clearly derived from L-methionine.
An efficient one-pot synthesis of N-alkyl carbamates from primary amines using Cs2CO3

Abstract A facile one-pot synthesis of N-alkyl carbamates is described. A primary amine, CO2, and an alkyl halide underwent a three-component coupling using cesium carbonate and tetrabutylammonium iodide (TBAI) giving rise to the resultant carbamate. In the presence of Cs2CO3, subsequent N-alkylation of the in situ generated carbamate with a different alkyl halide afforded various aliphatic N-alkyl carbamates, respectively.
Rearrangements of substituted 3-azidoazetidines: Unexpected formation of a substituted oxazole

Thermolysis of neat N-carboethoxy-3-azido-3-ethylazetidine (3) at 200° under argon produced the corresponding cyclic imine 4 (68% yield). Prolonged refluxing of a mixture of N-triflylazetidin-3-one (7), sodium azide, and titanium tetrachloride in acetonitrile solvent afforded recovered 7 (25% yield) along with a colorless microcrystalline solid, 8, mp 104–105° (20% yield), whose structure was established unequivocally via application of X-ray crystallographic methods.
Breeding nuclear fuels with accelerators — replacement for breeder reactors☆

Abstract High-current, high-energy linear accelerators are potential competitors to breeder reactors and fusion devices for the production of fissile fuel. Accelerator breeder studies, conducted at Chalk River (Canada) and Brookhaven National Laboratory during the last decade, indicate that the technology is available and system's costs competitive with that of the LMFBR and Fusion-Hybrid systems. This paper addresses the technical issues to be faced in an accelerator specifically designed for commercial operation of this kind, the neutronics and engineering feasibility of target systems, and related fuel-cycle cost/benefit analysis. A nearly optimized accelerator breeder concept consisting of a 1.5 GeV, 300 mA linear accelerator, and of a H2O-cooled, U-metal target (or thorium) has been designed and costed. Accelerator efficiency, beam-to-plug, is estimated at 50% and target power generation efficiency, beam-to-thermal output, at about 600% (U-metal case). Fuel costs produced by the facility are practically entirely driven by capital investment costs. This is also true for any competing system. On the basis, the accelerator breeder is economically competitive with the LMFBR while offering real advantages in terms of safety, fuel cycle flexibility, and resource independence.
On neutron star structure and the millisecond pulsar

The recently discovered millisecond pulsar (PSR1937-214) is observed to be rotating close to the limit of dynamical instability for a neutron star. Despite its extremely rapid rotation, measurements of the period derivative put a stringent upper limit on the energy loss from gravitational radiation, thus requiring that the quadrupole moment be quite small. The pulsar must also be rotating below the critical frequency at which its equilibrium configuration would become non-axisymmetric, since the lifetime of this configuration against decay by gravitational radiation is very short. This critical frequency, given by the theory of rotating ellipsoids, imposes a restriction on the rotation rate more severe than the break-up frequency and may be used to set a lower limit, rho 2 x 10 to the 14th power g/cu cm, on the density of the star. If the mass is 0.5 - 1.5 solar mass, several of the stiffer neutron star equations of state may be ruled out, and the radius should be less than 16 km. The condition for axisymmetry also imposes an upper limit on the rotation rate to which neutron stars may be spun up by accretion disks in binary systems, a model recently proposed for the evolution of the millisecond pulsar.
A Chandra-HETG VIEW OF MCG +8-11-11

United States. National Aeronautics and Space Administration (Chandra X-ray Observatory (U.S.) Award GO1-12147X)
Cyclopropanation of nitroso Diels-Alder cycloadducts and application to the synthesis of a 2',3'-methano carbocyclic nucleoside.

Abstract Treatment of nitroso Diels–Alder cycloadducts 1 with diazomethane in the presence of palladium acetate gives synthetically useful exo -6-oxa-7-azatricyclo[3.2.1.0 2,4 ]octane derivatives 7 in good to excellent yield. Using this methodology, a conformationally restricted 2′,3′-methano carbocyclic nucleoside was efficiently synthesized from nitroso cycloadduct 1a in seven steps.
A Facile Synthesis of 4-(Trialkylmethyl)anilines by the Reaction of 4-(Trifluoromethyl)aniline with Grignard Reagents

Abstract The treatment of 4-(trifluoromethyl)aniline (7) with primary Grignard reagents in ether yields the title products 14 (50–75%). A mechanistic pathway involves a series of fluoride elimination reactions followed by addition of the Grignard reagent to the resultant nonaromatic intermediate after each elimination step.
The complexity of Boolean formula minimization

The Minimum Equivalent Expression problem is a natural optimization problem in the second level of the Polynomial-Time Hierarchy. It has long been conjectured to be @S"2^P-complete and indeed appears as an open problem in Garey and Johnson (1979) [5]. The depth-2 variant was only shown to be @S"2^P-complete in 1998 (Umans (1998) [13], Umans (2001) [15]) and even resolving the complexity of the depth-3 version has been mentioned as a challenging open problem. We prove that the depth-k version is @S"2^P-complete under Turing reductions for all k>=3. We also settle the complexity of the original, unbounded depth Minimum Equivalent Expression problem, by showing that it too is @S"2^P-complete under Turing reductions.
Performance analysis of tapered gate in PD/SOI CMOS technology

‘Tapered gate’ is a device sizing methodology to improve the performance of critical paths in stacked circuit configurations. This paper presents a detailed study of the performance leverage of tapered gate in a partially depleted silicon-on-insulator (PD/SOI) technology. It is shown that the reduced junction capacitance in a PD/SOI device renders the series resistance reduction of the lower transistors in the stack more effective. The effects are also shown to be more pronounced for low-V T cases. The study demonstrates that tapered gate remains a viable device sizing technique/methodology for improving performance in a PD/SOI technology.
A Numerical Library and Its Support

Reflecting on four years of numerical consulting at the Stanford Linear Accelerator Center, we point out solved and outstanding problems in selecting and installing mathematical software, helping users, maintaining the library and monitoring its use, and managing the consulting operation.
Ozone Depletion from Nearby Supernovae

Estimates made in the 1970's indicated that a supernova occurring within tens of parsecs of Earth could have significant effects on the ozone layer. Since that time improved tools for detailed modeling of atmospheric chemistry have been developed to calculate ozone depletion, and advances have been made also in theoretical modeling of supernovae and of the resultant gamma ray spectra. In addition, one now has better knowledge of the occurrence rate of supernovae in the galaxy, and of the spatial distribution of progenitors to core-collapse supernovae. We report here the results of two-dimensional atmospheric model calculations that take as input the spectral energy distribution of a supernova, adopting various distances from Earth and various latitude impact angles. In separate simulations we calculate the ozone depletion due to both gamma rays and cosmic rays. We find that for the combined ozone depletion from these effects roughly to double the 'biologically active' UV flux received at the surface of the Earth, the supernova must occur at approximately or less than 8 parsecs.
(p-cymene)RuLCl2 (L = 1,3-Bis(2,4,6-trimethylphenyl)imidazol-2-ylidene and 1,3-Bis(2,6-diisopropylphenyl)imidazol-2-ylidene) and Related Complexes as Ring Closing Metathesis Catalysts

Complexes of (η6-arene)ruthenium bearing the carbene ligand 1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene (IMes) and 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene (IPr) Ru(IMes)(Cl)2(η6-arene), Ru(IPr)(Cl)2(η6-arene), and [RuCCCPh2(IMes)(Cl)(η6-arene)]PF6 were prepared and found to be efficient catalyst precursors for ring closing olefin metathesis.
Exact results for five-dimensional superconformal field theories with gravity duals

We apply the technique of supersymmetric localization to exactly compute the S 5 partition function of several large N superconformal field theories in five dimensions that have AdS6 duals in massive type IIA supergravity. The localization computations are performed in the non-renormalizable effective field theories obtained through relevant deformations of the UV superconformal field theories. We compare the S 5 free energy to a holographic computation of entanglement entropy in the AdS6 duals and find perfect agreement. In particular, we reproduce the N 5/2 scaling of the S 5 free energy that was expected from supergravity.
Automated Design of Controlled-Diffusion Blades

A numerical automation procedure has been developed to be used in conjunction with an inverse hodograph method for the design of controlled diffusion blades. With this procedure a cascade of airfoils with a prescribed solidity, inlet Mach number, inlet air flow angle, and air flow turning can be produced automatically. The trailing edge thickness of the airfoil, an important quantity in inverse methods, is also prescribed. The automation procedure consists of a multidimensional Newton iteration in which the objective design conditions are achieved by acting on the hodograph input parameters of the underlying inverse code. The method, although more general in scope, is applied in this paper to the design of axial flow compressor blade sections, and a wide range of examples is presented.
Zintl Chemistry for Designing High Efficiency Thermoelectric Materials

Zintl phases and related compounds are promising thermoelectric materials; for instance, high zT has been found in Yb14MnSb11, clathrates, and the filled skutterudites. The rich solid-state chemistry of Zintl phases enables numerous possibilities for chemical substitutions and structural modifications that allow the fundamental transport parameters (carrier concentration, mobility, effective mass, and lattice thermal conductivity) to be modified for improved thermoelectric performance. For example, free carrier concentration is determined by the valence imbalance using Zintl chemistry, thereby enabling the rational optimization of zT. The low thermal conductivity values obtained in Zintl thermoelectrics arise from a diverse range of sources, including point defect scattering and the low velocity of optical phonon modes. Despite their complex structures and chemistry, the transport properties of many modern thermoelectrics can be understood using traditional models for heavily doped semiconductors.
Linear collider capabilities for supersymmetry in dark matter allowed regions of the mSUGRA model

Recent comparisons of minimal supergravity (mSUGRA) model predictions with WMAP measurements of the neutralino relic density point to preferred regions of model parameter space. We investigate the reach of linear colliders (LC) with (s)1/2 = 0.5 and 1 TeV for SUSY in the framework of the mSUGRA model. We find that LCs can cover the entire stau co-annihilation region provided tanβ30. In the hyperbolic branch/focus point (HB/FP) region of parameter space, specialized cuts are suggested to increase the reach in this important ``dark matter allowed'' area. In the case of the HB/FP region, the reach of a LC extends well past the reach of the CERN LHC. We examine a case study in the HB/FP region, and show that the MSSM parameters μ and M2 can be sufficiently well-measured to demonstrate that one would indeed be in the HB/FP region, where the lightest chargino and neutralino have a substantial higgsino component.
A few weight systems arising from intersection graphs

This Article is brought to you for free and open access by the Mathematics at Digital Commons @ Loyola Marymount University and Loyola Law School. It has been accepted for inclusion in Mathematics Faculty Works by an authorized administrator of Digital Commons @ Loyola Marymount University and Loyola Law School. For more information, please contact digitalcommons@lmu.edu. Repository Citation Mellor, Blake, "A Few Weight Systems Arising from Intersection Graphs" (2003). Mathematics Faculty Works. Paper 38. http://digitalcommons.lmu.edu/math_fac/38
Probing Dark Energy with Baryonic Acoustic Oscillations from Future Large Galaxy Redshift Surveys

We show that the measurement of the baryonic acoustic oscillations in large high-redshift galaxy surveys offers a precision route to the measurement of dark energy. The cosmic microwave background provides the scale of the oscillations as a standard ruler that can be measured in the clustering of galaxies, thereby yielding the Hubble parameter and angular diameter distance as a function of redshift. This, in turn, enables one to probe dark energy. We use a Fisher matrix formalism to study the statistical errors for redshift surveys up to z = 3 and report errors on cosmography while marginalizing over a large number of cosmological parameters, including a time-dependent equation of state. With redshift surveys combined with cosmic microwave background satellite data, we achieve errors of 0.037 on ΩX, 0.10 on w(z = 0.8), and 0.28 on dw(z)/dz for the cosmological constant model. Models with less negative w(z) permit tighter constraints. We test and discuss the dependence of performance on redshift, survey conditions, and the fiducial model. We find results that are competitive with the performance of future Type Ia supernova surveys. We conclude that redshift surveys offer a promising independent route to the measurement of dark energy.
Lagrangian mechanics and variational integrators on two-spheres

Euler–Lagrange equations and variational integrators are developed for Lagrangian mechanical systems evolving on a product of two-spheres. The geometric structure of a product of two-spheres is carefully considered in order to obtain global equations of motion. Both continuous equations of motion and variational integrators completely avoid the singularities and complexities introduced by local parameterizations or explicit constraints. We derive global expressions for the Euler–Lagrange equations on two-spheres, which are more compact than existing equations written in terms of angles. Since the variational integrators are derived from Hamilton's principle, they preserve the geometric features of the dynamics such as symplecticity, momentum maps, or total energy, as well as the structure of the configuration manifold. Computational properties of the variational integrators are illustrated for several mechanical systems. In addition, Lie group variational integrators can be used to integrate Lagrangian flows on more general homogeneous spaces. This is achieved by lifting the discrete Hamilton's principle on homogeneous spaces to a discrete variational principle on the Lie group that is constrained by a discrete connection. Copyright © 2009 John Wiley & Sons, Ltd.
CONTRIBUTION TO THE EXTRAGALACTIC GAMMA-RAY BACKGROUND FROM THE CASCADES OF VERY HIGH ENERGY GAMMA RAYS FROM BLAZARS

As very high energy (VHE) photons propagate through the extragalactic background light (EBL), they interact with the soft photons and initiate electromagnetic cascades of lower energy photons and electrons. The collective intensity of a cosmological population emitting at VHEs will be attenuated at the highest energies through interactions with the EBL and enhanced at lower energies by the resulting cascade. We calculate the cascade radiation created by VHE photons produced by blazars and investigate the effects of cascades on the collective intensity of blazars and the resulting effects on the extragalactic gamma-ray background. We find that cascade radiation greatly enhances the collective intensity from blazars at high energies before turning over due to attenuation. The prominence of the resulting features depends on the blazar gamma-ray luminosity function, spectral index distribution, and the model of the EBL. We additionally calculate the cascade radiation from the distinct spectral sub-populations of blazars, BL Lacertae (BL Lacs) objects, and flat-spectrum radio quasars (FSRQs), finding that the collective intensity of BL Lacs is considerably more enhanced by cascade radiation than that of the FSRQs. Finally, we discuss the implications that this analysis and upcoming Fermi observations could have for the nature of the EBL, the evolution of blazars, blazar spectra, and other sources of gamma-ray radiation.
Weighted citation: An indicator of an article's prestige

The authors propose using the technique of weighted citation to measure an article's prestige. The technique allocates a different weight to each reference by taking into account the impact of citing journals and citation time intervals. Weightedcitation captures prestige, whereas citation counts capture popularity. They compare the value variances for popularity and prestige for articles published in the Journal of the American Society for Information Science and Technology from 1998 to 2007, and find that the majority have comparable status. © 2010 Wiley Periodicals, Inc.
Evolution of the Martian Atmosphere

Carbon dioxide, nitrogen, and the nonradiogenic and radiogenic noble gases are tracked from primordial inventories to their present states in a revised model of atmospheric evolution on Mars. Elemental and isotopic abundances evolve by hydrodynamic escape, impact erosion, outgassing, sputtering, photochemical escape of nitrogen, and carbonate formation and recycling. Atmospheric history is divided into early and late evolutionary periods, the first characterized by high CO2 pressures and a possible greenhouse and the second by a low pressure cap-regolith buffered system initiated by polar CO2 condensation approximately 3.7 Gyr ago. During early evolution the Xe isotopes are fractionated to their present composition by hydraulic escape, and CO2 pressure and isotopic history are dictated by the interplay of losses to erosion, sputtering, and carbonate precipitation, additions by outgassing and carbonate recycling, and perhaps also by feedback stabilization under greenhouse conditions. Atmospheric collapse near 3.7 Gyr leads to abrupt increases in the mixing ratios of preexisting Ar, Ne, and N2 at the exobase and their rapid removal by sputtering. Current abundances and isotopic compositions of these light species are therefore entirely determined by the action of sputtering and photochemical escape on gases supplied by outgassing during the late evolutionary epoch. The present atmospheric Kr inventory also derives almost completely from solar-like Kr degassed during this period. Consequently, among current observables, only the Xe isotopes and delta(C-13) survive as isotopic tracers of atmospheric history prior to its transition to low pressure.
Synthesis and structure of a new layer compound: ScPS4

ScPS4, which belongs to a new structure type, was prepared and characterized by_single crystal X-ray diffraction. It has a layer structure with seven-coordinate scandium. The space group is P1 and the lattice constants are a =6.445(5)/~, b=6.659(5)/~, c=6.211(4)/~, a=91.36(5),/3=98 .76(5), and 7=86.22(5). The final R/R~, for the crystal refinement was 4.9/5.1%.
Software compatibility: what was promised, what we have, what we need

Software compatibility is an extremely complex and pervasive topic. Unfortunately it is not well defined nor well documented. To say anything useful within the space and time constraints we must confine ourselves to generalities and readily admit in advance that there are many exceptions.
Technique for implantation of fiducial markers in the prostate.

Objectives To describe our experience in developing a technique for implanting fiducial markers (gold markers and electromagnetic transponders) in the prostate by the transrectal approach under ultrasound guidance. Methods Our technique requires an endocavitary probe (ultrasound transducer) designed for prostate imaging, an ultrasound system with software to visualize the biopsy trajectory on the imaging screen, and a needle guide specifically designed to fit the probe. Critical aspects of the technique include identifying appropriate implantation locations in the gland, correctly orienting the bevel of the implantation needles, ensuring that the bevel is completely within the gland before deploying markers, and achieving adequate spacing of the markers. Results Since 1999 we have successfully implanted gold markers in 705 patients. Only 1 patient has developed a urinary tract infection requiring additional antibiotic therapy. There have been no instances of severe rectal bleeding or gross hematuria requiring further intervention. Complication rates have been similarly low for electromagnetic transponders implanted in 44 patients. Conclusions Implantation of fiducial markers is being used to achieve greater accuracy of external beam radiation therapy for prostate cancer. Our experience can serve as a guide to clinicians for performing this increasingly important procedure in an effective and problem-free manner.
The Discovery of a Companion to the Lowest Mass White Dwarf

We report the detection of a radial velocity companion to SDSS J091709.55+463821.8, the lowest mass white dwarf currently known, with M ~ 0.17 M☉. The radial velocity of the white dwarf shows variations with a semi-amplitude of 148.8 ± 6.9 km s-1 and a period of 7.5936 ± 0.0024 hr, which implies a companion mass of M ≥ 0.28 M☉. The lack of evidence of a companion in the optical photometry forces any main-sequence companion to be smaller than 0.1 M☉, hence a low-mass main-sequence star companion is ruled out for this system. The companion is most likely another white dwarf, and we present tentative evidence for an evolutionary scenario that could have produced it. However, a neutron star companion cannot be ruled out, and follow-up radio observations are required to search for a pulsar companion.
The synthesis of γ-amino olefins. A novel intramolecular aziridine — allylsilane reaction

Abstract An intramolecular reaction of aziridines with allylsilanes has stereoselectively produced disubstituted cyclopentanes and cyclohexanes containing the γ-amino olefin unit.
Placement of Gastrostomy Tubes in Patients with Ventriculoperitoneal Shunts Does Not Result in Increased Incidence of Shunt Infection or Decreased Survival

The objective of this study was to examine if G-tube (G-tube) placement in patients with ventriculoperitoneal (VP) shunts results in shunt infection or impacts patient survival. We performed a retrospective cohort study. Patients underwent VP shunt and G-tube placement. Incidence of shunt infection and patient survival were calculated. Fifty-five patients qualified for the study. Shunt infection occurred in seven patients (12.5%). The incidence of shunt infection did not differ between surgically placed G-tubes (2/7=29%) and PEG tubes (5/7=71%; P=0.69). There was no difference in the risk of VP infection based on the order of placement (OR=0.61 [0.12-3.02]; P=0.69). No predictors for shunt infection were identified. Kaplan-Meier mortality estimates demonstrated a 21% 1-year mortality rate. There were no predictors of patient survival. We conclude that placement of G-tubes in patients with shunts is safe. The order of placement of G-tube and VP shunt does not affect the incidence of shunt infection or survival.
Enzymatic synthesis of a modified phospholipid and its evaluation as a substrate for B. cereus phospholipase C.

Abstract The novel phospholipid 2, which bears a tert-butyl moiety in place of the natural trimethyl ammonium group of phosphatidylcholine, has been enzymatically synthesized via a transphosphatidylation reaction mediated by phospholipase D. The change from the choline headgroup in 1 to the tert-butyl group in 2 reduced the efficiency of hydrolysis by the phosphatidylcholine-preferring phospholipase C from Bacillus cereus by a factor of greater than 103.
Mean rise rate of droplets in isotropic turbulence

This paper investigates the rise rate of droplets that are slightly lighter than the surrounding fluid. We experimentally investigate the effect of three parameters: Stokes number, turbulence intensity, and droplet Reynolds number. Droplets were injected into a chamber with nearly isotropic turbulence and little mean flow. The results show that at high turbulence intensity, the mean droplet rise rate is 25% of the root-mean-square velocity regardless of the Stokes number, while at low turbulence intensity, the droplets rise at a rate equal to the rise rate in a quiescent fluid. At intermediate turbulence intensity, the rise rate is strongly dependent on the Stokes number. Qualitative discussions explain these trends.
Decentralized optimal power pricing: the development of a parallel program

An algorithm for solving a large-scale optimization problem concerning decentralized pricing of electrical power has been implemented. To help abstract the communication and layout requirements of the problem away from the main algorithm, a small object system library has been developed. The results are an efficient and easily modifiable solution to the problem and a general approach to solving this class of problems. The formulation of the problem and the object system are considered in detail. >
Setting the boundary free in AdS/CFT

We describe a new class of boundary conditions for AdSd+1 under which the boundary metric becomes a dynamical field. The key technical point is to show that contributions from boundary counter-terms in the bulk gravitational action render such fluctuations normalizable. In the context of AdS/CFT, the simplest version of Neumann boundary conditions for AdS promotes the CFT metric to a dynamical field but adds no explicit gravitational dynamics; the gravitational dynamics is just that induced by the conformal fields. Other AdS boundary conditions couple the CFT to a gravity theory of choice. We use this correspondence to briefly explore the coupled CFT + gravity theories and, in particular, for d = 3 we show that coupling topologically massive gravity to a large N CFT preserves the perturbative stability of the theory with negative (three-dimensional) Newton's constant.
A Note on Multiple Equilibria and Punitive Damages Rules in "Everybody Out of the Pool"

This article describes two types of revealing equilibria in the presence of punitive damages meant to encourage truthful revelation of the safety of a product. Full information price (FIP) revealing equilibria occur when the equilibrium prices are those that would obtain under full information. Full information quantity (FIQ) revealing equilibria occur when the equilibrium quantities are those that would obtain under full information. We discuss the punitive damages policies which support each type of equilibrium and argue that FIP revealing equilibria are likely to be of greater interest. In a recent article in this journal (Daughety and Reinganum, 1997), we developed a model in which the safety of a product was unobservable to consumers prior to its purchase and use. The model involved a monopoly seller of the product, for which there were two potential levels of safety. Safety, an exogenous attribute of the product, was measured by the probability of harm to the consumer. We showed that, without punitive damages, a revealing equilibrium existed when the difference in the product safety levels was not too great; that is, consumers could infer safety from observing the price charged in the market. This revealing equilibrium involved each product type charging its full information price; skeptical consumers responded to the low price by buying for sure, but not buying for sure at the high price;l in the sequel, we refer to such an equilibrium as a "full information price" (or FIP) revealing equilibrium. We then asked whether such an equilibrium extended to the case in which the safety levels were significantly different and found that no FIP revealing equilibria existed under those circumstances. However, by employing a particular level of punitive damages in the event that a less-safe product misrepresented itself as a safer product, the FIP revealing equilibrium could be extended to all potential safety levels for the two product types. Assuming that
A new algorithm for suboptimal stochastic control

An apparently new stochastic control algorithm, called M -measurement-optimal feedback control, is described for discrete-time systems. This scheme incorporates M future measurements into the control computations: when M is zero,it reduces to the well-known open-loop-optimal feedback control; when M is the actual number of measurements remaining in the problem, it becomes the truly optimal stochastic control. This new algorithm may also be used to simplify computations when the plant is nonlinear, when the controls are constrained, or when the cost is nonquadratic. Simulation results are presented which show the superiority of the new algorithm over the open-loop-optimal feedback control.
On the complexity of simple arithmetic expressions

Let E be the set of all simple arithmetic expressions of the form E(x) = xTl…Tk where x is a nonnegative integer variable and each Ti is a multiplication or integer division by a positive integer constant. We investigate the complexity of the inequivalence and the bounded inequivalence problems for expressions in E. (The bounded inequivalence problem is the problem of deciding for arbitrary expressions E1(x) and E2(x) and a positive integer l whether or not E1(x) ≠ E2(x) for some nonnegative integer x<l. If l = ∞, i.e., there is no upper bound on x, the problem becomes the inequivalence problem.) We show that the inequivalence problem (or equivalently, the equivalence problem) for a large subclass of E is decidable in polynomial time. Whether or not the problem is decidable in polynomial time for the full class E remains open. We also show that the bounded inequivalence problem is NP-complete even if the divisors are restricted to be equal to 2. This last result can be used to sharpen some known NP-completeness results in the literature. Note that if division is rational division, all problems are trivially decidable in polynomial time.
Catalytic Enantioselective Pyrrole Alkylations of α,β-Unsaturated 2-Acyl Imidazoles

Enantioselective additions of pyrroles to α,β-unsaturated 2-acyl imidazoles catalyzed by the bis(oxazolinyl)pyridine−scandium(III) triflate complex (1) have been accomplished. The α,β-unsaturated 2-acyl imidazoles were synthesized in high yields through Wittig olefination. A short, enantioselective synthesis of the alkaloid (+)-heliotridane has been accomplished utilizing this methodology and a 2-acyl imidazole cleavage and cyclization. This methodology was then extended to the one-pot asymmetric synthesis of 2-substituted indoles.
Synthesis of Novel 3′-Methylene H-Phosphonate Thymidines.

Abstract The synthesis of novel 5′-DMT- and 5′-MMT-protected 3′-methylene H-phosphonate thymidines 1 – 6 , having methoxy, fluoro, hydrogen, and methoxyethoxy substituents at the 2′-position is reported.
The Status of Econometrics in the Economics Major: A Survey

In this article, the authors describe the place of econometrics in undergraduate economics curricula in all American colleges and universities that offer economics majors as listed in the U.S. News & World Report “Best Colleges 2010” guide (U.S. News & World Report 2009). Data come from online catalogs, departmental Web sites, and online course syllabi. About one-third of the schools require econometrics of all students majoring in economics, about half require it of none, and a sixth require it of some, but not all, economics majors. Among universities with economics PhD programs and liberal arts colleges, almost all those ranked in the top 10 require it. Below the top 10, there is little correlation between ranking and econometrics requirements. Liberal arts econometrics classes are much more likely to require research projects than their counterparts in universities.
Electro-optical design for efficient visual communication

Visual communication, in the form of telephotography and television, for example, can be regarded as efficient only if the amount of information that it conveys about the scene to the observer approaches the maximum possible and the associated cost approaches the minimum possible. Elsewhere we have addressed the problem of assessing the end to end performance of visual communication systems in terms of their efficiency in this sense by integrating the critical limiting factors that constrain image gathering into classical communications theory. We use this approach to assess the electro-optical design of image gathering devices as a function of the f number and apodization of the objective lens and the aperture size and sampling geometry of the phot-detection mechanism. Results show that an image gathering device that is designed to optimize information capacity performs similarly to the human eye. For both, the performance approaches the maximum possible, in terms of the efficiency with which the acquired information can be transmitted as decorrelated data, and the fidelity, sharpness, and clearity with which fine detail can be restored.
Engine Life Cycle Cost Modeling in the Conceptual Phase

The rising cost of weapon systems in a time of declining purchasing power of the defense budget has forced new procurement practices to tradeoff system and major component performance, with cost at the earliest moment. Major elements of weapon systems such as aircraft engines are prime candidates for such cost/performance evaluations during the conceptual phase of the procurement cycle. This paper deals with life cycle cost modeling techniques that use parametric data to derive information necessary for study by the Defense Acquisition Review Council for decision making. Typical examples of parametric cost/performance tradeoffs are highlighted.
Tricyanovinyl derivatives as acceptors

Abstract The preparation and characterisation of two new acceptors, p-hexacyanodivinylbenzene (HCDV) and i-hexacyanodivinylbenzene (i-HCDV) are described. The cyclic voltammetry of these acceptors shows two one electron reversible waves. The potential separation between the two electrochemical steps is smaller for the meta isomer i-HCDV. Recently Scalapino and Hirsch [1] have discovered by Montecarlo simulations that molecules which could be involved in a simultaneous two-electron transfer, may give rise to high Tc superconductivity. We reasoned that hexacyanodivinylbenzene, 1 may be a good acceptor candidate to test this proposal because the two tricyanovinyl moieties may act independently in electron transfer processes.
Primitives for the manipulation of three-dimensional subdivisions

Algorithms for manipulating three-dimensional cell complexes are seldom implemented due to the lack of a suitable data structure for representing them. Such a data structure is proposed here along with the primitive operations necessary to make it useful. Applications of the structure are also given.
A Model of International Trade and Finance

An equilibrium model of international trade, payments, and financial asset flows is developed with implications for the relationship between asset returns and changes in the relative prices of consumption goods of different countries. The model focuses on international trade as enlarging the opportunity for intertemporal exchange. The main source of uncertainty in the model is revisions of investors' expectations of the profitability of country-specific capital. The model is extended to include money to demonstrate how international monetary agreements may affect individual portfolio decisions.
Pituitary adenoma: The efficacy of radiotherapy as the sole treatment

The management of patients with pituitary adenomas by radiotherapy alone, using modern techniques of evaluation and current standards of treatment, has not been examined. This is a retrospective review of 29 such patients with nonfunctional or prolactin secreting pituitary macroadenomas. Patients were analyzed by visual fields, hormone levels, and CT scans. All but one patient received a tumor dose of 4500 cGy in 4 to 5 weeks. The tumor was controlled in 26 of 28 (93%) patients for an observed period of 3 to 14 years. Seventeen of 21 (81%) patients with visual impairment experienced normalization or improvement, and seven of ten (70%) patients with hyperprolactinemia achieved normalization of their serum prolactin levels. Post-treatment CT scanning revealed persistent tumor in nine of 17 patients despite clinical improvement. We conclude that: (a) radiotherapy is an effective treatment for these tumors; (b) doses need not exceed 4500 cGy in 25 fractions; (c) radiation is effective for improving vision; (d) radiation can normalize hyperprolactinemia; and (e) tumor regression is variable and unrelated to observed symptom regression.
Nonuniform sampling: Bandwidth and aliasing

For spectroscopic measurements, there are good reasons why one might consider using nonuniformly nonsimultaneously sampled complex data. The primary one is that the effective bandwidth, the largest spectral window free of aliases, can be much wider than with uniformly sampled data. In this article, we discuss nonuniformly nonsimultaneously sampled data, describe how these data are traditionally analyzed, analyze them using probability theory, and show how probability theory generalizes the discrete Fourier transform: first for uniformly sampled data, then for nonuniformly sampled data, and finally for nonuniformly nonsimultaneously sampled data. These generalizations demonstrate that aliases are not so much removed by nonuniform nonsimultaneous sampling as they are moved to much higher frequencies. © 2008 Wiley Periodicals, Inc. Concepts Magn Reson Part A 32A: 417–435, 2008.
On surfaces with prescribed shape operator

The problem of immersing a simply connected surface with a prescribed shape operator is discussed. It is shown that, aside from some special degenerate cases, such as when the shape operator can be realized by a surface with one family of principal curves being geodesic, the space of such realizations is a convex set in an affine space of dimension at most 3. The cases where this maximum dimension of realizability is achieved are analyzed and it is found that there are two such families of shape operators, one depending essentially on three arbitrary functions of one variable and another depending essentially on two arbitrary functions of one variable. The space of realizations is discussed in each case, along with some of their remarkable geometric properties. Several explicit examples are constructed.
Concentrations and emissions of polybrominated diphenyl ethers from U.S. houses and garages.

Concentrations of polybrominated diphenyl ethers (PBDEs) and other brominated flame retardants (BFRs) have been rapidly increasing in fish, birds, sediments, indoor environments, and humans, but emission sources and exposure pathways of these pollutants remain poorly understood. The many BFR-containing materials in buildings constitute a large reservoir of these compounds, and in-use releases from this reservoir may be a significant environmental source. To estimate in-use releases from building materials and contents in residences, we monitored 12 houses and garages in two seasons and combined measurements of BFRs in air and settled dust, air exchange rates, and other information in an approach that utilized the building as a “natural” test chamber. Results were scaled to provide a first estimate of aggregate emission rates from U.S. houses. PBDE releases total about 4 μg h−1 per house or 20 ng m−2 h−1, and U.S. houses and garages collectively release about 4100 kg y−1. Most of these releases are settled...
The depth of the associated graded ring of ideals with any reduction number

Abstract Let R be a local Cohen–Macaulay ring, let I be an R-ideal, and let G be the associated graded ring of I. We give an estimate for the depth of G when G is not necessarily Cohen–Macaulay. We assume that I is either equimultiple, or has analytic deviation one, but we do not have any restriction on the reduction number. We also give a general estimate for the depth of G involving the first r +l powers of I, where r denotes the Castelnuovo regularity of G and l denotes the analytic spread of I.
Effective string amplitudes for hadronic physics

Abstract We propose using the general structure and properties of conformal field theory amplitudes, in particular those defined on surfaces with boundaries, to explore effective string theory amplitudes for some hadronic processes. Two examples are considered to illustrate the approach. In one a natural mechanism for chiral symmetry breaking within the string picture is proposed. One consequence is that the vertex operator for pion emission (at zero momentum) behaves like a world-sheet current evaluated on the string boundary. This fact is used to rederive, in a more general setting, hadronic mass relations found in the early days of string theory by Lovelace, and Ademollo, Veneziano and Weinberg. In the second example, we derive the general structure of the form factor for the emission of a pomeron (interpreted as a closed string) from a meson or baryon. The result reconciles the interpretation of the pomeron as a closed string, emitted from the interior of the meson or baryon world-sheet, with the additive quark rules for total hadronic cross sections at high energies.
Flight-test base pressure measurements in turbulent flow

Determination of the recirculating base-flow properties in the near wake of a slender cone is important in several re-entry applications. Flight-test base pressure measurements for four relatively sharp, slender re-entry vehicles (RVs) are presented. The data encompass the hypersonic, supersonic, and subsonic flow regimes (M/sub infinity/ = 0.5 to 15) and are correlated to provide an empirical prediction capability for vehicles characterized by very low heatshield ablation rates in turbulent flow (mass addition parameter m/p/sub infinity/V/sub infinity/A/sub B/ less than 0.001).
Multimodality molecular imaging of the lung

Lung diseases cause significant morbidity and mortality and lead to high healthcare utilization. However, few lung disease-specific biomarkers are available to accurately monitor disease activity for the purposes of clinical management or drug development. Advances in cross-modal imaging technologies, such as combined positron emission tomography (PET) and magnetic resonance (MR) imaging scanners and PET or single-photon emission computed tomography (SPECT) combined with computed tomography (CT), may aid in the development of noninvasive, molecular-based biomarkers for lung disease. However, the lungs pose particular challenges in obtaining accurate quantification of imaging data due to the low density of the organ and breathing motion. This review covers the basic physics underlying PET, SPECT, CT, and MR lung imaging and presents technical considerations for multimodal imaging with regard to PET and SPECT quantification. It also includes a brief review of the current and potential clinical applications for these hybrid imaging technologies.
Stackelberg thresholds in network routing games or the value of altruism

Abstract It is well known that the Nash equilibrium in network routing games can have strictly higher cost than the optimum cost. In Stackelberg routing games, where a fraction of flow is centrally-controlled, a natural problem is to route the centrally-controlled flow such that the overall cost of the resulting equilibrium is minimized. We consider the scenario where the network administrator wants to know the minimum amount of centrally-controlled flow such that the cost of the resulting equilibrium solution is strictly less than the cost of the Nash equilibrium. We call this threshold the Stackelberg threshold and prove that for networks of parallel links with linear latency functions, it is equal to the minimum of the Nash flows on links carrying more optimum flow than Nash flow. Our approach also provides a simpler proof of characterization of the minimum fraction that must be centrally controlled to induce the optimum solution.
The Bombay stock exchange: seasonalities and investment opportunities

Investigates whether the Bombay Stock Exchange behaves like an efficient market, or whether it displays a typical seasonal pattern. Takes mean daily returns between 1979 and 1990 to discover by regression that there is a December effect. Considers whether this is because of holidays, broker recommendations or window dressing by mutual fund managers. Notes a weekend effect like the New York Stock Exchange, and considers Bombay to be weak‐form efficient; but points out that banking and transport are nationalized in India but private in the USA. Explains that government regulation, which prevents foreign trading in Bombay or Indian trading on the New York Stock Exchange, has left the Bombay exchange autonomous, less affected by external factors and more by domestic conditions.