cssi/SciSciGPT-SciSciNet huggingface dataset:
Synthesis and microbial hydroxylation of some azabicycloalkanes

Abstract N -Substituted 7-azabicyclo[2.2.1]heptanes have been synthesized in a short route. These compounds containing benzamide or benzenesulfonamide groups are good substrates for microbial oxidation of unactivated carbons by B. bassiana .
Comparison of 2D Memory SEU Transport Simulation with Experiments

Single event upset (SEU) simulations in SRAM cells have been carried out and the results are compared to experimental data on 16K bit memories. The simulations consisted of simultaneous calculations of charge transport and transient circuit response for four cross-coupled CMOS transistors following the introduction of a slab of excess carriers into the "off" p-channel drain. The experiments collected upset rates produced in the memories by 163 MeV argon ions directed normally to the chip surface. Agreement between experiment and calculation was achieved when (1) the p-channel transistors were integrated into a single block of silicon as in the memory cell layout and (2) scaling was done on the Auger coefficients to compensate for an inherent 2D effect.
Psychophysics with junctions in real images

Junctions, formed at the intersection of image contours, are thought to play an important and early role in vision. The interest in junctions can be attributed in part to the notion that they are local image features that are easy to detect but that nonetheless provide valuable information about important events in the world, such as occlusion and transparency. Here I test the notion that there are locally defined junctions in real images that might be detected with simple, early visual mechanisms. Human observers were used as a tool to measure the visual information available in local regions of real images. One set of observers was made to label all the points in a set of real images where one edge occluded another. A second set of observers was presented with variable-size circular subregions of these images, and was asked to judge whether the regions were centered on an occlusion point. This task is easy if junctions are visible, but I found performance to be poor for small regions, not approaching ceiling levels until observers were given fairly large (approximately 50 pixels in diameter) regions over which to make the judgment. Control experiments ruled out the possibility that the effects are just due to junctions at multiple scales. Experiments reported here suggest that, although some junctions in real images are locally defined and can be detected with simple mechanisms, a substantial fraction necessitate the use of more complex and global processes. This raises the possibility that junctions in such cases may not be detected prior to scene interpretation.
Supersymmetries in free fermionic strings

Abstract Consistent heterotic free fermionic string models are classified in terms of their number of spacetime supersymmetries, N . For each of the six distinct choices of gravitino sector, we determine what number of supersymmetries can survive additional GSO projections. We prove by exhaustive search that only three of the six can yield N = 1, in addition to the N = 4, 2, or 0 that five of the six can yield. One choice of gravitino sector can only produce N = 4 or 0. Relatedly, we find that only Z 2 , Z 4 , and Z 8 twists of the internal fermions with worldsheet supersymmetry are consistent with N = 1 in free fermionic models. Any other twists obviate N = 1.
The environmental and economic impact of removing growth-enhancing technologies from U.S. beef production

The objective of this study was to quantify the environmental and economic impact of withdrawing growth-enhancing technologies (GET) from the U.S. beef production system. A deterministic model based on the metabolism and nutrient requirements of the beef population was used to quantify resource inputs and waste outputs per 454 × 10(6) kg of beef. Two production systems were compared: one using GET (steroid implants, in-feed ionophores, in-feed hormones, and beta-adrenergic agonists) where approved by FDA at current adoption rates and the other without GET use. Both systems were modeled using characteristic management practices, population dynamics, and production data from U.S. beef systems. The economic impact and global trade and carbon implications of GET withdrawal were calculated based on feed savings. Withdrawing GET from U.S. beef production reduced productivity (growth rate and slaughter weight) and increased the population size required to produce 454 × 10(6) kg beef by 385 × 10(3) animals. Feedstuff and land use were increased by 2,830 × 10(3) t and 265 × 10(3) ha, respectively, by GET withdrawal, with 20,139 × 10(6) more liters of water being required to maintain beef production. Manure output increased by 1,799 × 10(3) t as a result of GET withdrawal, with an increase in carbon emissions of 714,515 t/454 × 10(6) kg beef. The projected increased costs of U.S. beef produced without GET resulted in the effective implementation of an 8.2% tax on beef production, leading to reduced global trade and competitiveness. To compensate for the increase in U.S. beef prices and maintain beef supply, it would be necessary to increase beef production in other global regions, with a projected increase in carbon emissions from deforestation, particularly in Brazil. Withdrawing GET from U.S. beef production would reduce both the economic and environmental sustainability of the industry.
Bisimulation can't be traced

In the concurrent language CCS, two programs are considered the same if they are bisimilar. Several years and many researchers have demonstrated that the theory of bisimulation is mathematically appealing and useful in practice. However, bisimulation makes too many distinctions between programs. We consider the problem of adding operations to CCS to make bisimulation fully abstract. We define the class of GSOS operations, generalizing the style and technical advantages of CCS operations. We characterize GSOS congruence in as a bisimulation-like relation called ready-simulation. Bisimulation is strictly finer than ready simulation, and hence not a congruence for any GSOS language.
Endo-selective enyne ring-closing metathesis promoted by stereogenic-at-Mo monoalkoxide and monoaryloxide complexes. Efficient synthesis of cyclic dienes not accessible through reactions with Ru carbenes.

Stereogenic-at-Mo monoalkoxide and monoaryloxide complexes promote enyne ring-closing metathesis (RCM) reactions, affording the corresponding endo products with high selectivity (typically >98:<2 endo:exo). All catalysts can be prepared and used in situ. Five-, six-, and seven-membered rings are obtained through reactions with enyne substrates that bear all-carbon tethers as well as those that contain heteroatom substituents. The newly developed catalytic protocols complement the related exo-selective Ru-catalyzed processes. In cases where Ru-based complexes deliver exo and endo products nondiscriminately, such as when tetrasubstituted cyclic alkenes are generated, Mo-catalyzed reactions afford the endo product exclusively. The efficiency of synthesis of N- and O-containing endo diene heterocycles can be improved significantly through structural modification of Mo catalysts. The modularity of Mo-based monopyrrolides is thus exploited in the identification of the most effective catalyst variants. Through a...
Closed-loop equilibrium in a multi-stage innovation race

We examine a multistage model of an RD in particular, a player may increase expenditures as his opponent moves ahead of him.
Low-complexity distributed scheduling algorithms for wireless networks

We consider the problem of designing distributed scheduling algorithms for wireless networks. We present two algorithms, both of which achieve throughput arbitrarily close to that of maximal schedules, but whose complexity is low due to the fact that they do not necessarily attempt to find maximal schedules. The first algorithm requires each link to collect local queue-length information in its neighborhood, and its complexity is otherwise independent of the size and topology of the network. The second algorithm, presented for the node-exclusive interference model, does not require nodes to collect queue-length information even in their local neighborhoods, and its complexity depends only on the maximum node degree in the network.
Breakup of particle clumps on liquid surfaces

Abstract The aim of this paper is to study the mechanism by which clumps of some powdered materials break up and disperse on a liquid surface to form a monolayer of particles. We show that a clump breaks up because when particles on its outer periphery come in contact with the liquid surface they are pulled into the interface by the vertical component of capillary force overcoming the cohesive forces which keep them attached, and then these particles move away from the clump. In some cases, the clump itself is broken into smaller pieces and then these smaller pieces break apart by the aforementioned mechanism. The newly-adsorbed particles move away from the clump, and each other, because when particles are adsorbed on a liquid surface they cause a flow on the interface away from themselves. This flow may also cause particles newly-exposed on the outer periphery of the clump to break away. Interestingly, when many particles asymmetrically break away from a clump, the clump itself is pushed in the opposite direction by the flow caused by the newly-adsorbed particles. Since millimeter-sized clumps can breakup and spread on a liquid surface within a few seconds, their behavior appears to be similar to that of some liquid drops which can spontaneously spread on solid surfaces. However, if the capillary force is not large enough to overcome the cohesive force holding the clump together, the clump may not breakup.
EVALUATING THE EFFECTS OF CASHING OUT EMPLOYER-PAID PARKING: EIGHT CASE STUDIES

Abstract California law requires many employers to offer commuters the option to choose cash in lieu of any parking subsidy offered. This report presents case studies of eight firms that have complied with California's cash-out requirement. For the 1,694 employees of the eight firms, the number of solo drivers to work fell by 17 percent after cashing out. The number of carpoolers increased by 64 percent, the number of transit riders increased by 50 percent, and the number who walk or bike to work increased by 39 percent. Vehicle-miles traveled for commuting to the eight firms fell by 12 percent. Carbon dioxide emissions from commuting fell by 367 kilograms per employee per year. The eight firms' spending for commuting subsidies rose by $2 per employee per month because payments in lieu of parking increased slightly more than spending for parking declined. Federal and state income tax revenues increased by $65 per employee per year because many commuters voluntarily traded tax-exempt parking subsidies for taxable cash. Employers praised the cash option for its simplicity and fairness, and said that it helped to recruit and retain employees. The benefit/cost ratio of the eight cash-out programs was at least 4 1 . In summary, these eight case studies show that cashing out employer-paid parking can benefit commuters, employers, taxpayers, and the environment. All these benefits derive from subsidizing people, not parking.
COOLING OF DENSE GAS BY H2O LINE EMISSION AND AN ASSESSMENT OF ITS EFFECTS IN CHONDRULE-FORMING SHOCKS

We consider gas at densities appropriate to protoplanetary disks and calculate its ability to cool due to line radiation emitted by H2O molecules within the gas. Our work follows that of Neufeld & Kaufman, expanding on their work in several key aspects, including use of a much-expanded line database, an improved escape probability formulism, and the inclusion of dust grains, which can absorb line photons. Although the escape probabilities formally depend on a complicated combination of optical depth in the lines and in the dust grains, we show that the cooling rate including dust is well approximated by the dust-free cooling rate multiplied by a simple function of the dust optical depth. We apply the resultant cooling rate of a dust-gas mixture to the case of a solar nebula shock pertinent to the formation of chondrules, millimeter-sized melt droplets found in meteorites. Our aim is to assess whether line cooling can be neglected in chondrule-forming shocks or if it must be included. We find that for typical parameters, H2O line cooling shuts off a few minutes past the shock front; line photons that might otherwise escape the shocked region and cool the gas will be absorbed by dust grains. During the first minute or so past the shock, however, line photons will cool the gas at rates ~104 K hr–1, dropping the temperature of the gas (and most likely the chondrules within the gas) by several hundred K. Inclusion of H2O line cooling therefore must be included in models of chondrule formation by nebular shocks.
The Caltech Faint Galaxy Redshift Survey. XII. Clustering of Galaxies

A clustering analysis is performed on two samples of ~600 faint galaxies each, in two widely separated regions of the sky, including the Hubble Deep Field. One of the survey regions is configured so that some galaxy pairs span angular separations of up to 1°. The median redshift is zmed ≈ 0.55. Strong clustering is obvious, with every pencil-beam field containing a handful of narrow redshift-space features, corresponding to galaxy structures with sizes of 5-20 Mpc. The structures are not obviously organized on planes, although one prominent, colinear triplet of structures is observed, spanning ~20 Mpc. This may be evidence of a filament. A galaxy-galaxy correlation function calculation is performed. No significant evolution of clustering (relative to stable clustering) is found in the redshift range 0.3 < z < 1.0. This is not surprising, since uncertainties in the correlation amplitude estimated from surveys such as these are large; field-to-field variations and covariances between data points are both shown to be significant. Consistent with other studies in this redshift range, the galaxy-galaxy correlation length is found to be somewhat smaller than that predicted from local measurements and an assumption of no evolution. Galaxies with absorption-line-dominated spectra show much stronger clustering at distances of <2 Mpc than typical field galaxies. There is some evidence for weaker clustering at intermediate redshift than at low redshift, when the results presented here are compared with surveys of the local universe. In subsets of the data, the measured pairwise velocity dispersion of galaxies ranges from 200 to 600 km s-1, depending on the properties of the dominant redshift structures in each subset.
Does female education prevent the spread of HIV-AIDS in Sub-Saharan Africa?

Cross-section estimates of 31 countries for the year 2000 are used to examine the effect of the level of female education, and the gap between male and female levels, on the prevalence of HIV/AIDS in Sub-Saharan Africa. Many standard types of education are analysed and a non-standard category involving under- and over-aged primary school enrollees are identified. Although it is found that female education is positively related to country infection rates, there is scope to reduce infection rates by substituting one type of education for another. It is estimated that female infection rates peak within 15–17 years of the first case reported.
SEMI-INFINITE FORMS AND TOPOLOGICAL VERTEX OPERATOR ALGEBRAS

Semi-infinite forms on the moduli spaces of genus-zero Riemann surfaces with punctures and local coordinates are introduced. A partial operad of semi-infinite forms is constructed. Using semi-infinite forms and motivated by a partial suboperad of the partial operad of semi-infinite forms, topological vertex partial operads of type k<0 and strong topological vertex partial operads of type k<0 are constructed. It is proved that the category of (locally-)grading-restricted (strong) topological vertex operator algebras of type k<0 and the category of (weakly) meromorphic ℤ×ℤ-graded algebras over the (strong) topological vertex partial operad of type k are isomorphic. As an application of this isomorphism theorem, the following conjecture of Lian-Zuckerman and Kimura-Voronov-Zuckerman is proved: A strong topological vertex operator algebra gives a (weak) homotopy Gerstenhaber algebra. These results hold in particular for the tensor product of the moonshine module vertex operator algebra, the vertex algebra constructed from a rank 2 Lorentz lattice and the ghost vertex operator algebra, studied in detail first by Lian and Zuckerman.
A subspace approach for enhancing speech corrupted by colored noise

A generalized subspace approach is proposed for enhancement of speech corrupted by colored noise. The proposed approach is based on the simultaneous diagonalization of the clean speech and noise covariance matrices, which is shown to be a generalization of the approach proposed by Ephraim and Van Trees for white noise. Objective and subjective measures demonstrated significant improvements over other subspace-based methods when tested with sentences corrupted with speech-shaped noise and multi-talker babble.
News related to future GDP growth as a risk factor in equity returns

Abstract A model that includes a factor that captures news related to future Gross Domestic Product (GDP) growth along with the market factor can explain the cross-section of equity returns about as well as the Fama-French model can. Furthermore, the Fama-French factors HML and SMB appear to contain mainly news related to future GDP growth. When news related to future GDP growth is present in the asset-pricing model, HML and SMB lose much of their ability to explain the cross-section.
EUV mask pilot line at Intel Corporation

The introduction of extreme ultraviolet (EUV) lithography into high volume manufacturing requires the development of a new mask technology. In support of this, Intel Corporation has established a pilot line devoted to encountering and eliminating barriers to manufacturability of EUV masks. It concentrates on EUV-specific process modules and makes use of the captive standard photomask fabrication capability of Intel Corporation. The goal of the pilot line is to accelerate EUV mask development to intersect the 32nm technology node. This requires EUV mask technology to be comparable to standard photomask technology by the beginning of the silicon wafer process development phase for that technology node. The pilot line embodies Intel's strategy to lead EUV mask development in the areas of the mask patterning process, mask fabrication tools, the starting material (blanks) and the understanding of process interdependencies. The patterning process includes all steps from blank defect inspection through final pattern inspection and repair. We have specified and ordered the EUV-specific tools and most will be installed in 2004. We have worked with International Sematech and others to provide for the next generation of EUV-specific mask tools. Our process of record is run repeatedly to ensure its robustness. This primes the supply chain and collects information needed for blank improvement.
Synthesis of fluorovinylsalicylic acids and their derivatives

Abstract Palladium-catalyzed cross-coupling of lodosalicylic acid derivatives with polyfluorovinyl zinc reagents provided the corresponding fluorovinyl-substituted salicylates. Methyl-5-(β,β)-difluorovinyl methyl salicylate was prepared by a Wittig reaction of the 5-formyl compound with the strongly nucleophilic ylide. ((Et2N),P-CF2. In one sequence, a fluorine-free benzofuran was obtained, instead of a difluorovinyl-salicylate.
Galaxy-Scale Strong-Lensing Tests of Gravity and Geometric Cosmology: Constraints and Systematic Limitations

Galaxy-scale strong gravitational lenses with measured stellar velocity dispersions allow a test of the weak-field metric on kiloparsec scales and a geometric measurement of the cosmological distance-redshift relation, provided that the mass-dynamical structure of the lensing galaxies can be independently constrained to a sufficient degree. We combine data on 53 galaxy-scale strong lenses from the Sloan Lens ACS Survey with a well-motivated fiducial set of lens-galaxy parameters to find (1) a constraint on the post-Newtonian parameter γ = 1.01 ± 0.05, and (2) a determination of ΩΛ = 0.75 ± 0.17 under the assumption of a flat universe. These constraints assume that the underlying observations and priors are free of systematic error. We evaluate the sensitivity of these results to systematic uncertainties in (1) total mass-profile shape, (2) velocity anisotropy, (3) light-profile shape, and (4) stellar velocity dispersion. Based on these sensitivities, we conclude that while such strong-lens samples can, in principle, provide an important tool for testing general relativity and cosmology, they are unlikely to yield precision measurements of γ and ΩΛ unless the properties of the lensing galaxies are independently constrained with substantially greater accuracy than at present.
Dynamical mean-field theory: from quantum impurity physics to lattice problems

Since the first investigation of the Hubbard model in the limit of infinite dimensions by Metzner and Vollhardt, dynamical mean-field theory (DMFT) has become a very powerful tool for the investigation of lattice models of correlated electrons. In DMFT the lattice model is mapped on an effective quantum impurity model in a bath which has to be determined self-consistently. This approach led to significant progress in our understanding of typical correlation problems such as the Mott transition; furthermore, the combination of DMFT with ab-initio methods now allows for a realistic treatment of correlated materials. The focus of these lecture notes is on the relation between quantum impurity physics and the physics of lattice models within DMFT. Issues such as the observability of impurity quantum phase transitions in the corresponding lattice models are discussed in detail.
Structure sensitive photoionization via Rydberg levels

The applicability of Rydberg spectroscopy as a method to fingerprint molecular structures is demonstrated on the example of the azulene/naphthalene system. The fingerprint characteristics of Rydberg spectra are distinctly different from those of other techniques, making the technique useful for the characterization of large-scale structural features. In addition, universal applicability to all neutral or positively charged ions, from small molecules to large composite or polymeric systems, is coupled with straightforward combination with traditional mass spectrometry.
Gender, Race, Age and Voting: A Research Note

In this brief analysis, we use a new dataset of two million voter registration records to demonstrate that gender, race, and age do not correlate with political participation in the ways that previous research has shown. Among Blacks and Latinos, women participate at vastly higher rates than men; many Blacks participate at higher rates than Whites; and the relationship between age and participation is both not linear and varies by race and gender. Survey research is unable to capture the true relationship between demographics and participation on account of survey bias and, more importantly, the non-linearity of effects. As a result, theories of participation, like the dominant resources-based models, have been built on faulty premises and tested with inadequate data. Our evidence calls for a renewed effort to understand election participation by utilizing large datasets, by being attentive to linearity assumptions, and by returning to theory.
Ovo1 links Wnt signaling with N-cadherin localization during neural crest migration

A fundamental issue in cell biology is how migratory cell behaviors are controlled by dynamically regulated cell adhesion. Vertebrate neural crest (NC) cells rapidly alter cadherin expression and localization at the cell surface during migration. Secreted Wnts induce some of these changes in NC adhesion and also promote specification of NC-derived pigment cells. Here, we show that the zebrafish transcription factor Ovo1 is a Wnt target gene that controls migration of pigment precursors by regulating the intracellular movements of N-cadherin (Ncad). Ovo1 genetically interacts with Ncad and its depletion causes Ncad to accumulate inside cells. Ovo1-deficient embryos strongly upregulate factors involved in intracellular trafficking, including several rab GTPases, known to modulate cellular localization of cadherins. Surprisingly, NC cells express high levels of many of these rab genes in the early embryo, chemical inhibitors of Rab functions rescue NC development in Ovo1-deficient embryos and overexpression of a Rab-interacting protein leads to similar defects in NC migration. These results suggest that Ovo proteins link Wnt signaling to intracellular trafficking pathways that localize Ncad in NC cells and allow them to migrate. Similar processes probably occur in other cell types in which Wnt signaling promotes migration.
Palladium-catalyzed enantioselective diboration of prochiral allenes.

Pd-catalyzed diboration of prochiral allenes occurs exclusively at the internal position and is remarkably accelerated in the presence of Lewis basic ligand structures. On the basis of preliminary observations, a chiral ligand was employed, and the enantiomeric excess of a variety of diboration products was found to be in the range of 86−92% ee. The chiral diboron reaction products should be useful in organic synthesis, and preliminary experiments suggest that they may participate in allylation reactions with a high level of chirality transfer.
On the theory of magnetotransport in a periodically modulated two-dimensional electron gas

A semiclassical theory based on the Boltzmann transport equation for a two-dimensional electron gas modulated along one direction with weak electrostatic or magnetic modulations is proposed. It is shown that oscillations of the magnetoresistivity ρ∥ corresponding to the current driven along the modulation lines observed at moderately low magnetic fields, can be explained as classical geometric resonances reflecting the commensurability of the period of spatial modulations and the cyclotron radius of electrons.
A TALE OF DWARFS AND GIANTS: USING A z = 1.62 CLUSTER TO UNDERSTAND HOW THE RED SEQUENCE GREW OVER THE LAST 9.5 BILLION YEARS*

We study the red sequence in a cluster of galaxies at z = 1.62 and follow its evolution over the intervening 9.5?Gyr to the present day. Using deep YJKs imaging with the HAWK-I instrument on the Very Large Telescope, we identify a tight red sequence and construct its rest-frame i-band luminosity function (LF). There is a marked deficit of faint red galaxies in the cluster that causes a turnover in the LF. We compare the red-sequence LF to that for clusters at z 0.6. In this model the cluster accretes blue galaxies from the field whose star formation is quenched and who are subsequently allowed to merge. We find that three to four mergers among cluster galaxies during the 4?Gyr between z = 1.62 and z = 0.6 match the observed LF evolution between the two redshifts. The inferred merger rate is consistent with other studies of this cluster. Our result supports the picture that galaxy merging during the major growth phase of massive clusters is an important process in shaping the red-sequence population at all luminosities.
Highly Stereoselective Methylene Transfers onto Butanediacetal-Protected Chiral Non-Racemic Sulfinyl Imines Using S-Ylide Technology

Diastereomeric ratios of >95 : 5 were obtained when performing methylene transfers onto imines originating from D-mannitol and (S)-(−)-2-methyl-2-propane sulfinamide or ascorbic acid and (R)-(−)-2-methyl-2-propane sulfinamide.
Self-regulated star formation in the galaxy

Assuming that star formation regions are supported against gravity by winds from low mass young objects, the stellar birthrate obtained for winds interacting in the momentum conservation stage is correlated with the molecular gas density of the parent fragment as n to the 13/8 power or n to the 5/8 power, respectively, for rates/unit volume or rates/unit mass. Birthrates derived from protostellar rotationally driven winds are in good agreement with the observed star production in the cloud B18. With the aid of observed Taurus-Auriga complex properties, the present model is extrapolated to the Galaxy as a whole, yielding a Milky Way predicted average rate that is in good agreement with standard estimates based on observations of the solar neighborhood.
Nonlinear nonequilibrium nonquantum nonchaotic statistical mechanics of neocortical interactions

The work in progress reported by Wright & Liley shows great promise, primarily because of their experimental and simulation paradigms. However, their tentative conclusion that macroscopic neocortex may be considered (approximately) a linear near-equilibrium system is premature and does not correspond to tentative conclusions drawn from other studies of neocortex.
Is the EGRET Source 3EG J1621+8203 the Radio Galaxy NGC?6251?

We discuss the nature of the unidentified EGRET source 3EG J1621+8203. In an effort to identify the gamma-ray source, we have examined X-ray images of the field from ROSAT PSPC, ROSAT HRI, and ASCA GIS. Of the several faint X-ray point sources in the error circle of 3EG J1621+8203, most are stars or faint radio sources, unlikely to be counterparts to the EGRET source. The most notable object in the gamma-ray error box is the bright FR I radio galaxy NGC 6251. If 3EG J1621+8203 corresponds to NGC 6251, then it would be the second radio galaxy to be detected in high-energy gamma rays after Cen A, which provided the first clear evidence of the detection above 100 MeV of an active galactic nucleus (AGN) with a large-inclination jet. If the detection of more radio galaxies by EGRET has been limited by its threshold sensitivity, there exists the exciting possibility that new high-energy gamma-ray instruments, with much higher sensitivity, will detect a larger number of radio galaxies in the future.
Oxypyriporphyrin, the First Fully Aromatic Porphyrinoid Macrocycle with a Pyridine Subunit

The synthesis of the first example of an aromatic pyridine-containing porphyrinoid 10 has been accomplished in excellent yields by the acid-catalyzed “3 + 1” condensation of 3-hydroxy-pyridinedicarboxaldehyde (8) with tri-pyrrane 9. The key intermediate 8 was obtained by the selenium dioxide oxidation of the known biscarbinol 7. The aromaticity of “oxypyriporphyrin” 10 has been confirmed by MS, NMR, IR, and UV/Vis spectroscopy. This system afforded a monocation in 0.2% TFA-chloroform, and a dication was observed in 2% TFA-chloroform; these species also retained macrocyclic aromaticity. Oxypyriporphyrin readily formed the corresponding metal chelates 14a-c by reaction with zinc, copper(II), or nickel(II) acetate, and this observation suggests that there are extensive possibilities for the use of 10 in coordination chemistry. Oxypyriporphyrin and the related semiquinone system oxybenziporphyrin represent the first two members of a new class of aromatic porphyrinoids.
Shape-Controlled Synthesis of Gold and Silver Nanoparticles

Monodisperse samples of silver nanocubes were synthesized in large quantities by reducing silver nitrate with ethylene glycol in the presence of poly(vinyl pyrrolidone) (PVP). These cubes were single crystals and were characterized by a slightly truncated shape bounded by {100}, {110}, and {111} facets. The presence of PVP and its molar ratio (in terms of repeating unit) relative to silver nitrate both played important roles in determining the geometric shape and size of the product. The silver cubes could serve as sacrificial templates to generate single-crystalline nanoboxes of gold: hollow polyhedra bounded by six {100} and eight {111} facets. Controlling the size, shape, and structure of metal nanoparticles is technologically important because of the strong correlation between these parameters and optical, electrical, and catalytic properties.
Coexistent lymphosarcoma and chronic granulocytic leukemia.

Excerpt The coexistence of lymphosarcoma and leukemias of lymphocytic origin is well established, but that of lymphosarcoma and leukemia of granulocytic origin is very rare. We are reporting the ca...
Photochemistry of Formic Acid Monomer at 222 nm

The yields of CO2 and CO formed from the gas-phase photolysis at 222 nm of very low pressures of formic acid where the monomer predominates have been determined using FTIR spectroscopy. The observed ratio of CO2/CO approaches unity as the formic acid pressure approaches zero. Previous studies have shown that the quantum yield for HCOOH + hv OH + HCO (or H + CO) is 0.70 at 298 K. The present experimental results indicate that the ratio of the quantum yields of the possible molecular photolysis channels forming H2 + CO2 (ϕ1b) and H2O + CO (ϕ1c) is ca. 1. Including this result in an analysis of previously reported quantum yields of CO and CO2 determined at higher pressures of formic acid, where both monomer and dimer contribute significantly to the products, indicates that ϕ1b = ϕ1c = 0. © 1994 John Wiley & Sons, Inc.
Period-luminosity relations for Galactic Cepheid variables with independent distance measurements

In this paper, we derive the period-luminosity (PL) relation for Galactic Cepheids with recent independent distance measurements from open cluster, Barnes-Evans surface brightness, interferometry and Hubble Space Telescope astrometry techniques. Our PL relation confirms the results from recent works, which showed that the Galactic Cepheids follow a different PL relation to their Large Magellanic Cloud (LMC) counterparts. Our results also show that the slope of the Galactic PL relation is inconsistent with the LMC slope with more than 95 per cent confidence level. We apply this Galactic PL relation to find the distance to NGC 4258. Our result of μ o = 29.49 ± 0.06 mag (random error) agrees at the ∼1.4σ level with the geometrical distance of μ = 29.28 ± 0.15 mag from water maser measurements.
Photospheric emission as the dominant radiation mechanism in long-duration gamma-ray bursts

We present the results of a set of numerical simulations of long-duration gamma-ray burst jets associated with massive, compact stellar progenitors. The simulations extend to large radii and allow us to locate the region in which the peak frequency of the advected radiation is set before the radiation is released at the photosphere. Light curves and spectra are calculated for different viewing angles as well as different progenitor structures and jet properties. We find that the radiation released at the photosphere of matter-dominated jets is able to reproduce the observed Amati and energy-Lorentz factor correlations. Our simulations also predict a correlation between the burst energy and the radiative efficiency of the prompt phase, consistent with observations.
WHAT WE KNOW AND WHAT WE DON'T KNOW ABOUT THE UNIVERSE

I present a non-technical and necessarily biased and incomplete overview of our present understanding of the physical universe and its constituents, emphasizing what we have learned from the explosive growth in cosmological and astrophysical data acquisition and some of the key open questions that remain. The topics are organized under the labels space, time, and matter. Most bibliographical references are for the non-expert.
PROTOSTELLAR DISK DYNAMOS AND HYDROMAGNETIC OUTFLOWS IN PRIMORDIAL STAR FORMATION

Are magnetic fields important in primordial star formation? Assuming that star formation occurs via an accretion disk that is turbulent, initially because of local gravitational instability, we calculate the disk structure for realistic accretion rates. We predict that local gravitational viscosity is able to drive accretion, without the disk fragmenting. We then estimate the rate of dynamo amplification of seed magnetic field. Turbulence in a stratified disk can be helical, with different signs of the helicity in each hemisphere. This provides a key ingredient for production of global-scale magnetic fields whose sign of flux is sustained over many orbit times. The resulting fields can drive collimated protostellar outflows that reduce the star formation efficiency from the initial gas cloud, especially once the protostar has contracted to the main sequence, at ~100 M☉. We estimate that the outflows are powerful enough to eject some material from the host dark matter halo and to initiate relatively strong magnetization of the local intergalactic medium. Close to the protostar, the outflow acts to shield the disk and equatorial regions from radiative feedback, such as ionizing photons, and this may enable accretion up to relatively large stellar masses. We conclude that magnetic fields cannot be ignored in models of primordial star formation.
Complexity of Linear Circuits and Geometry

We use algebraic geometry to study matrix rigidity and, more generally, the complexity of computing a matrix---vector product, continuing a study initiated in Kumar et al. (2009), Landsberg et al. (preprint). In particular, we (1) exhibit many non-obvious equations testing for (border) rigidity, (2) compute degrees of varieties associated with rigidity, (3) describe algebraic varieties associated with families of matrices that are expected to have super-linear rigidity, and (4) prove results about the ideals and degrees of cones that are of interest in their own right.
Synthesis of peptide thiazolines from β-hydroxythioamides. An investigation of racemization in cyclodehydration protocols

Abstract The formation of thiazolines from β-hydroxythioamides under TsCl/Et3N, SOCl2, and Mitsunobu conditions leads to extensive epimerization at the C(2) exo methine position. In contrast, thiazolines of >94% diastereomeric purity are isolated when the Burgess cyclodehydration protocol is applied.
Local inhomogeneity in asymmetric simple exclusion processes with extended objects

Totally asymmetric simple exclusion processes (TASEP) with particles which occupy more than one lattice site and with a local inhomogeneity far away from the boundaries are investigated. These non-equilibrium processes are relevant for the understanding of many biological and chemical phenomena. The steady-state phase diagrams, currents and bulk densities are calculated using a simple approximate theory and extensive Monte Carlo computer simulations. It is found that the phase diagram for TASEP with a local inhomogeneity is qualitatively similar to homogeneous models, although the phase boundaries are significantly shifted. The complex dynamics is discussed in terms of domain-wall theory for driven lattice systems.
On the Colored Jones Polynomial and the Kashaev invariant

We express the colored Jones polynomial as the inverse of the quantum determinant of a matrix with entries in the q-Weyl algebra of q-operators, evaluated at the trivial function (plus simple substitutions). The Kashaev invariant is proved to be equal to another special evaluation of the determinant. We also discuss the similarity between our determinant formula of the Kashaev invariant and the determinant formula of the hyperbolic volume of knot complements, hoping it will lead to a proof of the volume conjecture.
A novel design for polarization-independent single-pump fiber-optic parametric amplifiers

We propose a novel design for making the gain of single-pump, fiber-optic parametric amplifiers polarization independent. We show that under suitable conditions, signal gain varies by < 0.1 dB as its polarization varies.
Isotope resolution of the iron peak

Abstract A stack of Lexan detectors from the Apollo 17 mission has been analyzed to obtain Z measurements of sufficient accuracy to resolve the iron peak into its isotopic components. Within this distribution several peaks are present. With the centrally located, most populated peak assumed to be 56Fe, our measurements imply that the abundances of 54Fe and 58Fe are appreciable fractions of the 56Fe abundance. This result is in agreement with those of Webber et al. and Siegman et al. but in disagreement with the predictions of Tsao et al.
Total synthesis of (-)-okilactomycin.

A highly convergent synthesis of (−)-okilactomycin is described. Key reactions of this synthesis include a strategy-level diastereoselective oxy-Cope rearrangement/oxidation sequence, a Petasis−Ferrier union/rearrangement tactic, and an efficient RCM reaction to construct the 13-membered macrocyclic ring.
1,3,5 / 2,4,6-Differentiated hexaalkynylbenzenes: absorption and fluorescence properties of a D3h-symmetric donor-substituted system

Abstract The synthesis of 1,3,5 / 2,4,6 differentially functionalized hexaethynylbenzene derivatives is described. Interesting solvatochromic behavior was observed for 9b in the absorption and emission spectra. A twisted intramolecular charge transfer (TICT) state in polar solvents appears to be involved.
UNDERSTANDING THE QUANTUM HALL EFFECT USING THE S-MATRIX APPROACH

The origin of the quantum Hall effect is discussed in terms of the transmission probabilities of states at the Fermi‐level. A new argument for the existence of extended states near the center of the Landau level is given. Disequilibrium between edge and bulk currents in the extended state region is shown to give rise to non‐local and geometry‐dependent behavior of the Hall and longitudinal resistance. A model is discussed in which a new intensive ‘‘resistivity’’ is defined and used to generate quantitative predictions for the resistance of GaAs Hall conductors.
Pathways to faceting of vesicles

The interplay between geometry, topology and order can lead to geometric frustration that profoundly affects the shape and structure of a curved surface. In this commentary we show how frustration in this context can result in the faceting of elastic vesicles. We show that, under the right conditions, an assortment of regular and irregular polyhedral structures may be the low energy states of elastic membranes with spherical topology. In particular, we show how topological defects, necessarily present in any crystalline lattice confined to spherical topology, naturally lead to the formation of icosahedra in a homogeneous elastic vesicle. Furthermore, we show that introducing heterogeneities in the elastic properties, or allowing for non-linear bending response of a homogeneous system, opens non-trivial pathways to the formation of faceted, yet non-icosahedral, structures.
Effects of a Pleasant Ambient Fragrance on Simulated Driving Performance The Sweet Smell of... Safety

Eighty undergraduates performed a simulated driving task that required them to keep a moving target within defined boundaries (compensatory tracking); they also performed this task while responding to randomly occurring visual stimuli (stop signs). They performed these tasks in the presence or absence of a pleasant fragrance and after receiving or not receiving a small gift. A significant Fragrance x Gift interaction indicated that performance on both tasks was significantly enhanced by pleasant fragrance but only when participants did not also receive a gift. A main effect of gift condition indicated that performance on both tasks was significantly reduced by receipt of a small gift. In a follow-up study, 5 minutes of exposure to a pleasant fragrance was found to produce significant increments in participants' positive affect and alertness. Results were interpreted as suggesting that in the absence of other sources of positive affect, exposure to a pleasant fragrance can enhance some aspects of driving p...
The Tropical Totally Positive Grassmannian

Tropical algebraic geometry is the geometry of the tropical semiring (?, min, +). The theory of total positivity is a natural generalization of the study of matrices with all minors positive. In this paper we introduce the totally positive part of the tropicalization of an arbitrary affine variety, an object which has the structure of a polyhedral fan. We then investigate the case of the Grassmannian, denoting the resulting fan Trop+ Grk,n. We show that Trop+ Gr2,n is the Stanley-Pitman fan, which is combinatorially the fan dual to the (type An?3) associahedron, and that Trop+ Gr3,6 and Trop+ Gr3,7 are closely related to the fans dual to the types D4 and E6 associahedra. These results are strikingly reminiscent of the results of Fomin and Zelevinsky, and Scott, who showed that the Grassmannian has a natural cluster algebra structure which is of types An?3, D4, and E6 for Gr2,n, Gr3,6, and Gr3,7. We suggest a general conjecture about the positive part of the tropicalization of a cluster algebra.
A novel synthesis of 4-alkyl-4-(4-methoxyphenyl)cyclohex-2-en-1-ones and the Sceletium alkaloid, o-methyljoubertiamine.

Abstract The dianion formed by reduction of (η6:η6-4,4′-dimethoxybiphenyl)[Cr(CO)3]2 reacts with electrophiles such as methyl or ethyl triflate or allyl tosylate at −78 °C followed by CF3CO2H and I2 to form 4-alkyl-4-(4-methoxyphenyl)cyclohex-2-en-1-ones.
Nanowire addressing with randomized-contact decoders

Methods for assembling crossbars from nanowires (NWs) have been designed and implemented and methods for controlling individual NWs within a crossbar have also been proposed. However, implementation remains a challenge. A NW decoder is a device that controls many NWs with a much smaller number of lithographically produced mesoscale wires (MWs). Unlike traditional demultiplexers, all proposed NW decoders are assembled stochastically. In a randomized-contact decoder (RCD), for example, field-effect transistors are randomly created at about half of the NW/MW junctions. In this paper, we tightly bound the number of MWs required to produce a correctly functioning RCD with high probability. We show that the number of MWs is logarithmic in the number of NWs, even when manufacturing errors occur. We also analyze the overhead associated with controlling a stochastically assembled decoder. As we explain, lithographically-produced control circuitry must store information regarding which MWs control which NWs. This requires more area than the MWs themselves, but has received little attention elsewhere. Finally we analyze several simple testing algorithms for configuring this control circuitry. We demonstrate an unexpected tradeoff between testing time and the number of MWs required by an RCD.
PP-wave/CFT_2 duality

We investigate the pp-wave limit of the AdS_3 × S^3 × K3 compactification of type-IIB string theory from the point of view of the dual Sym_N(K3) CFT. It is proposed that a fundamental string in this pp-wave geometry is dual to the c = 6 effective string of the Sym_N(K3) CFT, with the string bits of the latter being composed of twist operators. The massive fundamental string oscillators correspond to certain twisted Virasoro generators in the effective string. It is shown that both the ground states and the genus expansion parameter (at least in the orbifold limit of the CFT) coincide. Surprisingly the latter scales like J^2/N rather than the J^4/N^2 which might have been expected. We demonstrate a leading-order agreement between the pp-wave and CFT particle spectra. For a degenerate special case (one NS 5-brane) an intriguing complete agreement is found.
A method for describing the doses delivered by transmission x-ray computed tomography.

A method for describing the absorbed dose delivered by x-ray transmission computed tomography (CT) is proposed which provides a means to characterize the doses resulting from CT procedures consisting of a series of adjacent scans. The dose descriptor chosen is the average dose at several locations in the imaged volume of the central scan of the series. It is shown that this average dose, as defined, for locations in the central scan of the series can be obtained from the integral of the dose profile perpendicular to the scan plane at these same locations for a single scan. This method for estimating the average dose from a CT procedure has been evaluated as a function of the number of scans in the multiple scan procedure and location in the dosimetry phantom using single scan dose profiles obtained from five different types of CT systems. For the higher dose regions in the phantoms, the multiple scan dose descriptor derived from the single scan dose profiles overestimates the multiple scan average dose by no more than 10%, provided the procedure consists of at least eight scans.