cssi/SciSciGPT-SciSciNet huggingface dataset:
Developed Country Trade Barriers and the Least Developed Countries: The Current Situation

In the 2001 Doha Development Round ministerial declaration, countries committed themselves “to the objective of duty-free, quota-free market access for products originating from LDCs.” In this light, this paper investigates the current tariff barriers put in place and preferences granted by the Triad countries regarding products from LDCs. It first investigates preferences in policy-the simple average tariffs faced by LDCs-and then looks at barriers in practice, analyzing the extent to which LDCs have been able to take advantage of the variety of preferences granted. It also explores the LDC tariff barriers against goods from other countries. It finds that Triad tariff barriers against LDC products have fallen dramatically and are especially low in the EU. However, barriers remain against certain products in which LDCs specialize, so that U.S. import-weighted tariffs for LDC goods are actually higher than U.S. import-weighted tariffs for goods of countries subject to MFN tariffs. Furthermore, the LDCs themselves tend to favor goods from the advanced industrial countries. These results indicate that there is still much room for tariff reductions for LDC goods, especially in the United States, and that such reductions must take account of LDC production capabilities.
Hepatitis B and C coinfections and persistent hepatitis B infections: Clinical outcome and liver pathology after transplantation

Hepatitis B virus (HBV) and hepatitis C virus (HCV) infections are common complications after orthotopic liver transplantation (OLT), but the liver pathology and clinical outcomes of HBV infection with HCV coinfection have not been thoroughly examined. In this study, we used the polymerase chain reaction (PCR) to detect HBV and HCV in pre- and post-OLT sera of 38 patients and correlated the findings with clinical outcome and liver pathology. Of 13 patients who were HBV and HCV negative before OLT, 9 acquired HBV infection, and 4 developed acquired HBV and HCV coinfections after OLT. Persistent HBV infections were present in 10 patients. Three patients with pre-OLT HBV infections developed persistent HBV and acquired HCV coinfections after OLT; 5 with pre-OLT HCV infections developed acquired HBV and persistent HCV coinfections after OLT, and 7 had persistent HBV and HCV coinfections before and after OLT. Portal/periportal inflammation was the same in all groups; however, lobular inflammation and fibrosis were more severe in patients with persistent HBV infections and in those with acquired HBV and HCV coinfections. Two major histopathological patterns were present in patients with HBV and HCV coinfections, one with predominant features of HCV infection, and the other with those of HBV infection. Patients with post-OLT HBV and HCV coinfections had survival rates similar to those with acquired HBV infection, whereas patients with persistent HBV infections experienced more allograft loss caused by chronic hepatitis or fibrosing cytolytic hepatitis, and had a more dire clinical outcome than the others. Although the limited numbers reported in this study prevent a definitive conclusion, our data suggest that in patients with HBV and HCV coinfections, the presence of HCV may improve the clinical outcome as compared with the expected outcome of persistent HBV infection alone.
Comparing Greenbook and Reduced Form Forecasts Using a Large Realtime Dataset

Many recent articles have found that atheoretical forecasting methods using many predictors give better predictions for key macroeconomic variables than various small-model methods. The practical relevance of these results is open to question, however, because these articles generally use ex post revised data not available to forecasters and because no comparison is made to best actual practice. We provide some evidence on both of these points using a new large dataset of vintage data synchronized with the Fed’s Greenbook forecast. This dataset consist of a large number of variables as observed at the time of each Greenbook forecast since 1979. We compare realtime, large dataset predictions to both simple univariate methods and to the Greenbook forecast. For inflation we find that univariate methods are dominated by the best atheoretical large dataset methods and that these, in turn, are dominated by Greenbook. For GDP growth, in contrast, we find that once one takes account of Greenbook’s advantage in ev...
Multigrid method for a vortex breakdown simulation

In this paper we study an inviscid model for a steady axisymmetric flow with siwrl. The governing equation is a nonlinear elliptic equation which has more than one solution for a certain range of the swirl parameter. The physically interesting solutions have closed streamlines that look like vortex breakdown ('bubble'-like solutions). A multigrid method is used to find these solutions. Using an FMG algorithm (nested iteration), the problem is solved in just a few multigrid cycles.
Distributed construction of connected dominating set in wireless ad hoc networks

Connected dominating set (CDS) has been proposed as virtual backbone or spine of wireless ad hoc networks. Three distributed approximation algorithms have been proposed in the literature for minimum CDS. In this paper, we first reinvestigate their performances. None of these algorithms have constant approximation factors. Thus these algorithms cannot guarantee to generate a CDS of small size. Their message complexities can be as high as O(n2), and their time complexities may also be as large as O(n2) and O(n3). We then present our own distributed algorithm that outperforms the existing algorithms. This algorithm has an approximation factor of at most 8, O(n) time complexity and O(n log n) message complexity. By establishing the Ω(n log n) lower bound on the message complexity of any distributed algorithm for nontrivial CDS, our algorithm is thus message-optimal.
Two-Group Dynamic Conflict Scenarios: “Toy Model” with a Severity Index

This article draws on several research domains and disciplines—social psychology, models of complex systems, and planning scenario analysis—to propose a “toy” model of the dynamics of intergroup conflicts. The ingroup–outgroup conflict literature supports the notion that inside groups in conflict there are subgroups of intransigents seeking to “fight it out,” and flexibles seeking avenues for settlements. There is also support for the intransigents and flexibles in the two groups being susceptible to each other's goading to escalate conflicts or entreaties to reach agreement. However, since two-group conflicts are embedded in complex systems with which they interact, it is difficult to predict outcomes and to assess the chances that intervention strategies might succeed or fail. We propose to use the model of two-group conflicts based on the mutual susceptibilities of flexibles and intransigents (Kaufman & Kaufman, 2013) to construct toy model scenarios of possible conflict trajectories. For each scenario, we compute a Severity Index for Conflicts (SIC) that captures the likelihood that it will end in confrontation (rather than agreement). We offer some examples of intranational and international conflicts and show how the scenarios can be analyzed qualitatively to explore the range of possible outcomes. Further developments will include sensitivity analyses for various assumptions and asking “what if” questions that can inform strategies of response and intervention.
Optimal regularity for the Signorini problem

We prove under general assumptions that solutions of the thin obstacle or Signorini problem in any space dimension achieve the optimal regularity C1,1/2. This improves the known optimal regularity results by allowing the thin obstacle to be defined in an arbitrary C1,β hypersurface, β > 1/2, additionally, our proof covers any linear elliptic operator in divergence form with smooth coefficients. The main ingredients of the proof are a version of Almgren’s monotonicity formula and the optimal regularity of global solutions.
Cost-Scaling Laws Applicable To Very Large Optical Telescopes

Cost and weight data for optical and radio telescopes are analyzed to derive scaling laws appropriate to the design and costing of very large telescopes of the future. A scaling law exponent close to the 2.0 power of aperture diameter is found for telescopes of comparable sophistication ranging from a 0.4 m to 5.0 m aperture, in contrast to the often cited 2.7 exponent. Predicted characteristics for a 25-meter aperture steerable dish Next Generation Telescope (NGT) are 5 x 10 6 kg, 20 $/kg and a total cost of 1.3 x 10 8 $.
Constructing isothermal curvature line coordinates on surfaces which admit them

Isothermic parameterizations are synonyms of isothermal curvature line parameterizations, for surfaces immersed in Euclidean spaces. We provide a method of constructing isothermic coordinate charts on surfaces which admit them, starting from an arbitrary chart. One of the primary applications of this work consists of numerical algorithms for surface visualization.
Diagnostic technique for monitoring high temperature plasma dynamics

A preliminary design for the adaptation of a pinhole experiment (PINEX) technique to the monitoring of the dynamics of high temperature plasmas is described. Specifically, this imaging technique uses a thick aperture, an efficient radiation converter, and highly intensified television cameras to provide real-time viewing of radiation sources such as the neutron emissions from d-d and d-t fusion reactions in controlled thermonuclear research devices. The neutron emission strengths, R approx. 5 x 10/sup 15/ n/s, recently achieved at the Tokamak Fusion Test Reactor (TFTR) and the Joint European Torus (JET) should be sufficient for 3 to 6-cm spatial resolution and 10 to 100-ms time resolution using such a system. Such information should be useful for on-line optimization of the plasma and for quantitative evaluation of its performance.
Stereoselective additions of thiyl radicals to terminal ynamides.

Two complementary sets of conditions for radical additions of thiols to terminal ynamides are described. The use of 1 equiv of thiol affords the cis-β-thioenamide adducts in rapid fashion (10 min) and good dr, whereas employing excess thiol and longer reaction times favors the trans products.
Holomorphic Anomaly in Gauge Theory on ALE space

We consider four-dimensional Ω-deformed $${\mathcal{N} = 2}$$ supersymmetric SU(2) gauge theory on A 1 space and its lift to five dimensions. We find that the partition functions can be reproduced via special geometry and the holomorphic anomaly equation. Schwinger-type integral expressions for the boundary conditions at the monopole/dyon point in moduli space are inferred. The interpretation of the five-dimensional partition function as the partition function of a refined topological string on A 1 × (local $${\mathbb{P}^{1} \times \mathbb{P}^1}$$ ) is suggested.
Synthesis of 2'-deoxyuridine nucleosides with appended 5-position carbonyl cross-linking groups

Abstract A simple modification of Stille type carbonylative coupling conditions resulted in high yield reactions giving new carbonyl appended 2′-deoxyuridine derivatives useful for chemical cross-linking.
3-D vision and figure/ground separation by visual cortex

A neural network theory of three-dimensional (3-D) vision, called FACADE theory, is described. The theory proposes a solution of the classical figure-ground problem for biological vision. It does so by suggesting how boundary representations and surface representations are formed within a boundary contour system (BCS) and a feature contour system (FCS). The BCS and FCS interact reciprocally to form 3-D boundary and surface representations that are mutually consistent. Their interactions generate 3-D percepts wherein occluding and occluded object parts are separated, completed, and grouped. The theory clarifies how preattentive processes of 3-D perception and figure-ground separation interact reciprocally with attentive processes of spatial localization, object recognition, and visual search. A new theory of stereopsis is proposed that predicts how cells sensitive to multiple spatial frequencies, disparities, and orientations are combined by context-sensitive filtering, competition, and cooperation to form coherent BCS boundary segmentations. Several factors contribute to figure-ground pop-out, including: boundary contrast between spatially contiguous boundaries, whether due to scenic differences in luminance, color, spatial frequency, or disparity-partially ordered interactions from larger spatial scales and disparities to smaller scales and disparities; and surface filling-in restricted to regions surrounded by a connected boundary. Phenomena such as 3-D pop-out from a 2-D picture, Da Vinci stereopsis, 3-D neon color spreading, completion of partially occluded objects, and figure-ground reversals are analyzed. The BCS and FCS subsystems model aspects of how the two parvocellular cortical processing streams that join the lateral geniculate nucleus to prestriate cortical area V4 interact to generate a multiplexed representation of Form-And-Color-And-DEpth, orfacade, within area V4. Area V4 is suggested to support figure-ground separation and to interact with cortical mechanisms of spatial attention, attentive object learning, and visual search. Adaptive resonance theory (ART) mechanisms model aspects of how prestriate visual cortex interacts reciprocally with a visual object recognition system in inferotemporal (IT) cortex for purposes of attentive object learning and categorization. Object attention mechanisms of the What cortical processing stream through IT cortex are distinguished from spatial attention mechanisms of the Where cortical processing stream through parietal cortex. Parvocellular BCS and FCS signals interact with the model What stream. Parvocellular FCS and magnocellular motion BCS signals interact with the model Where stream. Reciprocal interactions between these visual, What, and Where mechanisms are used to discuss data about visual search and saccadic eye movements, including fast search of conjunctive targets, search of 3-D surfaces, selective search of like-colored targets, attentive tracking of multielement groupings, and recursive search of simultaneously presented targets.
Apigenin-induced prostate cancer cell death is initiated by reactive oxygen species and p53 activation

Apigenin, a plant flavone, potentially activates wild-type p53 and induces apoptosis in cancer cells. We conducted detailed studies to understand its mechanism of action. Exposure of human prostate cancer 22Rv1 cells, harboring wild-type p53, to growth-suppressive concentrations (10–80 μM) of apigenin resulted in the stabilization of p53 by phosphorylation on critical serine sites, p14ARF-mediated downregulation of MDM2 protein, inhibition of NF-κB/p65 transcriptional activity, and induction of p21/WAF-1 in a dose- and time-dependent manner. Apigenin at these doses resulted in ROS generation, which was accompanied by rapid glutathione depletion, disruption of mitochondrial membrane potential, cytosolic release of cytochrome c, and apoptosis. Interestingly, we observed accumulation of a p53 fraction to the mitochondria, which was rapid and occurred between 1 and 3 h after apigenin treatment. All these effects were significantly blocked by pretreatment of cells with the antioxidant N-acetylcysteine, p53 inhibitor pifithrin-α, and enzyme catalase. Apigenin-mediated p53 activation and apoptosis were further attenuated by p53 antisense oligonucleotide treatment. Exposure of cells to apigenin led to a decrease in the levels of Bcl-XL and Bcl-2 and increase in Bax, triggering caspase activation. Treatment with the caspase inhibitors Z-VAD-FMK and DEVD-CHO partially rescued these cells from apigenin-induced apoptosis. In vivo, apigenin administration demonstrated p53-mediated induction of apoptosis in 22Rv1 tumors. These results indicate that apigenin-induced apoptosis in 22Rv1 cells is initiated by a ROS-dependent disruption of the mitochondrial membrane potential through transcriptional-dependent and -independent p53 pathways.
Cooperation over finite horizons: A theory and experiments

Abstract This paper shows that the presence of different types of players – those who only care about their own material payoffs and those who reciprocate others' contributions – can explain the robust features of observed contribution patterns in public good contribution games, even without the presence of asymmetric information. We show what conditions on reciprocity are sufficient for a unique perfect equilibrium, in which contributions are decreasing. Under these conditions, selfish players have enough future benefits to induce subsequent contributions by reciprocal players, and this incentive diminishes as the end of the game approaches. The model explains the puzzling restart effect and is consistent with various other empirical findings. We also report the results of a series of experiments, using a probabilistic continuation design in which after each set of 10-period games, the group is restarted with low probability. We find specific support for the theory in our data, including that selfish players (identified exogenously) stop contributing earlier than reciprocal players, as directly implied by the model.
New solid-gas metathetical synthesis of binary metal polysulfides and sulfides at intermediate temperatures: utilization of boron sulfides.

A new simple synthetic method for binary metal polysulfides and sulfides was developed by utilizing an in situ formation of boron sulfides and their subsequent reactions with metal-source oxides in a closed container at intermediate temperatures above 350 °C at which the boron sulfides react in a gaseous form. The versatility of the new method is demonstrated with oxides of various transition metals (Ti, V, Mn, Fe, Ni, Nb, Mo, Ru, and W) and rare-earth metals (Y, Ce, Nd, Sm, Eu, Tb, and Er) as starting materials that exhibit different chemical characteristics. Regardless of the oxidation states of metals in the starting materials, the sulfidation reactions occurred quantitatively with stoichiometric mixtures of boron and sulfur, and within 24 h the reactions yielded pure products of TiS2, TiS3, VS4, FeS2, NiS2, NbS3, MoS2, RuS2, WS2, Y2S3, and RS2 (R = Ce, Nd, Sm, Eu, Tb, and Er) which were the thermodynamically stable phases under the reaction conditions. The scope and implications of the new sulfidation...
INSECT POLLINATION IN THE CYCAD ZAMIA PUMILA (ZAMIACEAE)

A wind and insect exclusion pollination experiment was conducted in a wild population of the cycad Zamia pumila L. in Florida. Cones from which insects but not wind were excluded produced no viable seeds, while cones from which wind but not insects were excluded produced abundant viable seeds. Two beetle species have been identified which may be effecting pollination. Adults and larvae of both beetles are found abundantly on the male cones, and adults of both species and larvae of one species are found occasionally on female cones. Z. pumila produces sugar and amino acid-rich micropyle droplets which may serve as pollinator rewards. Mimicry of resource-rich male cones by female cones and the use of cones as refuges between mating and feeding bouts may account for beetle movement from male to female cones.
Ring closing metathesis for the formation of medium ring ethers: the total synthesis of (−)-isolaurallene

Abstract The total synthesis of the marine metabolite (−)-isolaurallene is described. Two approaches to the core nine-membered ether are presented both of which are based on a ring closing metathesis to close the cyclic ether.
Vane Row Indexing for Passive Vibration Control of Axial-Flow Turbomachine Rotors

A mathematical model is developed to analyze vane row indexing for passive e ow-induced vibration control. A compressible e at-plate cascade analysis is extended to account for the induced velocities due to the potential e elds of adjacent blade rows. Then, this model is applied to a baseline stator ‐rotor‐stator cone guration with the effects of Mach number, steady vane loading, and axial spacing investigated. For the particular geometry analyzed, the minimum unsteady lift and maximum unsteady moment responses occur near the unindexed position of the stator vane rows; simply decreasing the axial spacing markedly affects the rotor-blade unsteady aerodynamic response. However, by indexing the stator vanes, signie cant reductions in the unsteady lift and moment are achieved at the close spacings. At the closest spacing, near complete cancellation of the unsteady lift is possible at low Mach numbers. At high Mach numbers, there are optimum combinations of upstream and downstream rotor ‐stator axial spacings, which can result in complete cancellation of the unsteady lift, with signie cant reductions in the unsteady lift possible even for a moderate axial spacing of 30% chord.
Corrugation of roads

Abstract We present a one dimensional model for the development of corrugations in roads subjected to compressive forces from a flux of cars. The cars are modeled as damped harmonic oscillators translating with constant horizontal velocity across the surface, and the road surface is subject to diffusive relaxation. We derive dimensionless coupled equations of motion for the positions of the cars and the road surface H ( x , t ), which contain two phenomenological variables: an effective diffusion constant Δ ( H ) that characterizes the relaxation of the road surface, and a function a ( H ) that characterizes the plasticity or erodibility of the road bed. Linear stability analysis shows that corrugations grow if the speed of the cars exceeds a critical value, which decreases if the flux of cars is increased. Modifying the model to enforce the simple fact that the normal force exerted by the road can never be negative seems to lead to restabilized, quasi-steady road shapes, in which the corrugation amplitude and phase velocity remain fixed.
Some connections between quantum tunneling and inflation

Abstract The Wheeler-DeWitt equation in the minisuperspace approximation is studied in four different models. Under certain circumstances each model leads to a tunneling potential and under the same circumstances the classical version of each model leads to inflation.
Kink-Based Path Integral Calculations of Atoms He-Ne

Abstract An adaptive, kink-based path integral formalism is used to calculate the ground state energies of the atoms He–Ne. The method uses an adaptive scheme to virtually eliminate the sign difficulties. This is done by using a Monte Carlo scheme to identify states that contribute significantly to the canonical partition function and then include them in the wavefunctions to calculate the canonical averages. The calculations use the 6-31G basis set and obtain both precision and accuracy.
Verifying the identity of high‐redshift massive galaxies through the clustering of lower mass galaxies around them

Massive high-redshift galaxies form in overdense regions where the probability of forming other galaxies is also strongly enhanced. Given an observed flux of a galaxy, the inferred mass of its host halo tends to be larger as its inferred redshift increases. As the mass and redshift of a galaxy halo increase, the expected clustering of other galaxies around it gets stronger. It is therefore possible to verify the high-redshift identity of a galaxy (prior to an unambiguous spectral identification) from the clustering of other galaxies around it. We illustrate this method for the massive galaxy suggested by Mobasher et al. to be at redshift z ∼ 6.5. If this galaxy were to exist at z ∼ 6.5, there should have been a mean of ∼10 galaxies larger than a hundredth of its mass and having z-band magnitudes less than ∼22 detected as i-dropouts in the Hubble Ultra Deep Field (HUDF). We calculate an approximate probability distribution for neighbour galaxies and determine that there is less than a ∼0.3 per cent chance of detecting no massive neighbour galaxies. The lack of other massive z ∼ 6.5 galaxies in the HUDF image argues that the Mobasher et al. galaxy is instead a low-redshift interloper. We generalize our results to other galaxy masses and redshifts.
Heterotic flux attractors

We find attractor equations describing moduli stabilization for heterotic compactifications with generic SU(3)-structure. Complex structure and Kahler moduli are treated on equal footing by using SU(3) × SU(3)-structure at intermediate steps. All independent vacuum data, including VEVs of the stabilized moduli, is encoded in a pair of generating functions that depend on fluxes alone. We work out an explicit example that illustrates our methods.
Advanced pubertal status at age 11 and lower physical activity in adolescent girls.

Objective To examine the relationship between pubertal timing and physical activity. Study design A longitudinal sample of 143 adolescent girls was assessed at ages 11 and 13 years. Girls' pubertal development was assessed at age 11 with blood estradiol levels, Tanner breast staging criteria, and parental report of pubertal development. Girls were classified as early maturers (n = 41) or later maturers (n = 102) on the basis of their scores on the 3 pubertal development measures. Dependent variables measured at age 13 were average minutes/day of moderate to vigorous and vigorous physical activity as measured by the ActiGraph accelerometer. Results Early-maturing girls had significantly lower self-reported physical activity and accumulated fewer minutes of moderate to vigorous and vigorous physical activity and accelerometer counts per day at age 13 than later maturing girls. These effects were independent of differences in percentage body fat and self-reported physical activity at age 11. Conclusion Girls experiencing early pubertal maturation at age 11 reported lower subsequent physical activity at age 13 than their later maturing peers. Pubertal maturation, in particular early maturation relative to peers, may lead to declines in physical activity among adolescent girls.
A Mass Computation Model for Lightweight Brayton Cycle Regenerator Heat Exchangers

Based on a theoretical analysis of convective heat transfer across large internal surface areas, this paper discusses the design implications for generating lightweight gas-gas heat exchanger designs by packaging such areas into compact three-dimensional shapes. Allowances are made for hot and cold inlet and outlet headers for assembly of completed regenerator (or recuperator) heat exchanger units into closed cycle gas turbine flow ducting. Surface area and resulting volume and mass requirements are computed for a range of heat exchanger effectiveness values and internal heat transfer coefficients. Benefit cost curves show the effect of increasing heat exchanger effectiveness on Brayton cycle thermodynamic efficiency on the plus side, while also illustrating the cost in heat exchanger required surface area, volume, and mass requirements as effectiveness is increased. The equations derived for counterflow and crossflow configurations show that as effectiveness values approach unity, or 100 percent, the required surface area, and hence heat exchanger volume and mass tend toward infinity, since the implication is that heat is transferred at a zero temperature difference. To verify the dimensional accuracy of the regenerator mass computational procedure, calculation of a regenerator specific mass, that is, heat exchanger weight per unit working fluid mass flow, is performed in both English and SI units. Identical numerical values for the specific mass parameter, whether expressed in lb/(lb/sec) or kg/(kg/sec), show the dimensional consistency of overall results.
More Robust Hashing: Cuckoo Hashing with a Stash

Cuckoo hashing holds great potential as a high-performance hashing scheme for real applications. Up to this point, the greatest drawback of cuckoo hashing appears to be that there is a polynomially small but practically significant probability that a failure will occur during the insertion of an item, requiring an expensive rehashing of all items in the table. In this paper, we show that this failure probability can be dramatically reduced by the addition of a very small constant-sized stash. We demonstrate both analytically and through simulations that stashes of size equivalent to only three or four items yield tremendous improvements, enhancing cuckoo hashing's practical viability in both hardware and software. Our analysis naturally extends previous analyses of multiple cuckoo hashing variants, and the approach may prove useful in further related schemes.
The State of the Global E&P Industry: Is the World Running Out of Oil?

This paper examines trends in recoverable oil reserves and performance measures in the global upstream petroleum industry for evidence to support or reject the view that the world is running out of oil. The performance measures discussed include the appreciation ratio of recoverable reserves; the replacement rate of produced reserves; reserves to production (R/P) ratios; and the equitable-depletion index. Empirical analysis of these indicators suggests a growing world abundance of crude oil and no strong evidence to support the imminent worldwide petroleum-exhaustion theory. The analysis shows that the global oil supply market is well positioned to support even a modest growth in world petroleum demand despite institutional and regulatory barriers on resource development in some of the more intensely explored and developed regions of the world. In fact, the current estimate of worldwide remaining recoverable reserves can sustain the current worldwide production rate for at least the next 2 to 3 decades, with all other factors remaining constant and assuming a tolerable reserve-life index of 20 years.
Interpolation theorems for self-adjoint operators

We prove a complex and a real interpolation theorems on Besov spaces and Triebel-Lizorkin spaces associated with a selfadjoint operator \( \mathcal{L} \), without assuming the gradient estimate for its spectral kernel. The result applies to the cases where \( \mathcal{L} \) is a uniformly elliptic operator or a Schrodinger operator with electro-magnetic potential.
Millennium Modem/Channelizer Special Test Equipment

A broadband modem/channelizer test set developed by NASA Lewis Research Center is discussed. The test set is a fully programmable, bit-error-rate (BER) test set designed for broadband modem-only and multichannel demultiplexer/demodulator characterization. It is currently configured for testing a multichannel demultiplexer/demodulator and was developed for the Advanced Research and Projects Agency under a Technology Reinvestment Program Cooperative Agreement entitled 'Millennium: 21st Century Broadband Digital Telecommunications Technology.' The test set can easily be modified to provide testing of other modems and multichannel demultiplexer/demodulator systems and is available to industry for such testing.
Remarks on turbulent constitutive relations

The paper demonstrates that the concept of turbulent constitutive relations can be used to construct general models for various turbulent correlations. Some of the Generalized Cayley-Hamilton formulas for relating tensor products of higher extension to tensor products of lower extension are introduced. The combination of dimensional analysis and invariant theory can lead to 'turbulent constitutive relations' (or general turbulence models) for, in principle, any turbulent correlations. As examples, the constitutive relations for Reynolds stresses and scalar fluxes are derived. The results are consistent with ones from Renormalization Group (RNG) theory and two-scale Direct-Interaction Approximation (DIA) method, but with a more general form.
Clofarabine Targets the Large Subunit (α) of Human Ribonucleotide Reductase in Live Cells by Assembly into Persistent Hexamers

Clofarabine (ClF) is a drug used in the treatment of leukemia. One of its primary targets is human ribonucleotide reductase (hRNR), a dual-subunit, (α(2))(m)(β(2))(n), regulatory enzyme indispensable in de novo dNTP synthesis. We report that, in live mammalian cells, ClF targets hRNR by converting its α-subunit into kinetically stable hexamers. We established mammalian expression platforms that enabled isolation of functional α and characterization of its altered oligomeric associations in response to ClF treatment. Size exclusion chromatography and electron microscopy documented persistence of in-cell-assembled-α(6). Our data validate hRNR as an important target of ClF, provide evidence that in vivo α's quaternary structure can be perturbed by a nonnatural ligand, and suggest small-molecule-promoted, persistent hexamerization as a strategy to modulate hRNR activity. These studies lay foundations for documentation of RNR oligomeric state within a cell.
Predictors of early growth in academic achievement: the head-toes-knees-shoulders task

Children’s behavioral self-regulation and executive function (EF; including attentional or cognitive flexibility, working memory, and inhibitory control) are strong predictors of academic achievement. The present study examined the psychometric properties of a measure of behavioral self-regulation called the Head-Toes-Knees-Shoulders (HTKS) by assessing construct validity, including relations to EF measures, and predictive validity to academic achievement growth between prekindergarten and kindergarten. In the fall and spring of prekindergarten and kindergarten, 208 children (51% enrolled in Head Start) were assessed on the HTKS, measures of cognitive flexibility, working memory (WM), and inhibitory control, and measures of emergent literacy, mathematics, and vocabulary. For construct validity, the HTKS was significantly related to cognitive flexibility, working memory, and inhibitory control in prekindergarten and kindergarten. For predictive validity in prekindergarten, a random effects model indicated that the HTKS significantly predicted growth in mathematics, whereas a cognitive flexibility task significantly predicted growth in mathematics and vocabulary. In kindergarten, the HTKS was the only measure to significantly predict growth in all academic outcomes. An alternative conservative analytical approach, a fixed effects analysis (FEA) model, also indicated that growth in both the HTKS and measures of EF significantly predicted growth in mathematics over four time points between prekindergarten and kindergarten. Results demonstrate that the HTKS involves cognitive flexibility, working memory, and inhibitory control, and is substantively implicated in early achievement, with the strongest relations found for growth in achievement during kindergarten and associations with emergent mathematics.
Airfoil Row/Wake Interactions in a High-Speed Axial Compressor

Experiments are performed to study and quantify the time-varying characteristics of inlet guide vane (IGV) wakes interacting with the exit flowfield of a downstream high-speed rotor. Data define the IGV wake pressure and velocity fields across two vane passages and time resolved over one rotor blade passing period. Results show that the interaction of the rotor wake with the IGV wake has a significant effect on both the IGV and rotor wakes. When the rotor wakes are in phase with the IGV wakes, the IGV wake velocity deficit, semiwake width, and total pressure losses increase. The maximum and minimum velocity and total pressure envelopes over one rotor blade passing period decrease with distance from the rotor due to the decay of the rotor wake. More importantly, the differences between the velocity and total pressure maximum and minimum are smaller in the IGV wake regions; therefore, the rotor wakes have reduced fluctuations. The position of the IGV wake centerline moves under the influence of the rotor cutting action and exit flowfield. The IGV vortical and potential harmonic gust forcing functions downstream of the rotor are determined by a vortical/potential gust splitting analysis. The first harmonic vortical and potential gust magnitudes have two maximums over one rotor blade passing period that occur before and after the IGV and rotor wakes are in phase. Also, the higher harmonics of the temporally averaged instantaneous vortical and potential gusts decay at a very slow rate as they propagate.
Factors influencing the stereoselectivity in the cycloaddition of imino-dienophiles derived from amino ethers, amino alcohols, and amino acid esters

Abstract Imino dienophiles derived from amino ethers, amino alcohols and amino esters undergo Lewis acid promoted cycloaddition with Danishefsky's diene. Cyclic chelation between the imine and oxygen atom increases the stereoselectivity of the reaction.
On a deformation of 3-branes

Abstract We construct an explicit class of solutions of type IIB supergravity that is a smooth deformation of the 3-brane class of solutions. The solution is nonsupersymmetric and involves nontrivial dilaton and axion fields as well as the standard 5-form field strength. One of the main features of the solution is that for large values of the radius the deformation is small and it asymptotically approaches the undeformed 3-brane solution, signaling a restoration of conformal invariance in the UV for the dual gauge theory. We suggest that the supergravity deformation corresponds to an effective mass deformation on the dual gauge theory and consequently the deformed theory has the undeformed one as an ultraviolet fixed point. In cases where the original 3-brane solution preserves some amount of supersymmetry we suggest that the gauge theory interpretation is that of soft supersymmetry breaking. We discuss the deformation for D3-branes on the conifold and the generalized conifold explicitly. We show that the semiclassical behavior of the Wilson loop suggests that the corresponding gauge theory duals are confining.
W plus two jets from a quasi-inert Higgs doublet

We show that, the result recently reported by the CDF collaboration showing an excess in the invariant mass distribution of jet pairs produced in association with a W-boson can be explained by a simple extension of the Standard Model (SM) with an additional quasi-inert Higgs doublet. The two additional neutral Higgs states H 0 and A 0 have a mass of about 150 GeV and decay into a pair of jets. W H 0 =A 0 pairs are produced from the decay of the heavier charged Higgs boson H . Depending on the precise masses of the neutral and charged Higgs bosons, the model is shown to be in agreement with constraints from electroweak precision tests and from flavor physics for a broad range of the Standard Model-like Higgs mass from 100 GeV to several hundreds of GeV. Other possible signals of this model at the Tevatron and the LHC are discussed.
AN EXCEL-BASED DECISION SUPPORT SYSTEM FOR SCORING AND RANKING PROPOSED R&D PROJECTS

One of the most challenging aspects of technology management is the selection of research and development (R&D) projects from among a group of proposals. This paper introduces an interactive, user-friendly decision support system for evaluating and ranking R&D projects and demonstrates its application on an example R&D program. It employs the scoring methodology developed by Henriksen and Traynor to provide a practical technique that considers both project merit and project cost in the evaluation process, while explicitly accounting for trade-offs among multiple decision criteria.1 The framework of the Excel-based system, PScore, is presented with an emphasis on the potential benefits of using this methodology with computer-automated extensions that facilitate and enhance managerial review and decision-making capabilities.
A factor analysis approach to measure the biased effects of retail fruit juice advertising

This study presents a structural factor analysis approach to measure the impact of advertising on consumer demand. It is assumed that advertising affects the latent perception of consumers, which in turn influences their purchasing behavior. This study investigates the relationship between consumer purchases and retail store advertising (i.e., newspaper advertising, in-store display, and point-of-purchase display) of three fruit juices using an extended Rotterdam model. The results show that the demand for orange juice and grapefruit juice was affected by their own advertising, while the demand for apple juice was only affected by advertising of competitive juices.
The X-Ray Characteristics of a Classical Gamma-Ray Burst and Its Afterglow

The serendipitous observation of GRB 780506 by coaligned γ-ray (HEAO 1 A-4 0.02-6 MeV) and X-ray (HEAO 1 A-2 2-60 keV) instruments during a 6 hr pointing at a blank section of the sky gave us unprecedented high signal-to-noise ratio X-ray spectra and light curves of a γ-ray burst and its afterglow. First, the spectra: although the time resolution was only 10.24 s, it was possible to derive unambiguous position constraints and a reliable instrument response. We therefore could see two breaks in the initial spectrum, one consistent with a peak in νFν of ~45 keV and one below 4 keV, consistent with strong absorption. The event exhibited dramatic spectral variability, hardening as it rose to each peak, and softening as it fell, similar to behavior reported above 100 keV from other bursts. The initial strong turnover below a few keV evolved into a slight excess as the burst progressed. The spectral shape varied widely outside low-energy limits prescribed by current relativistic shock models. At no time was there evidence for any lines, either in emission or absorption. Overall, ~20% of the total energy was radiated in nonthermal 2-30 keV X-rays. Second, the light curve: the X-ray proportional counters were able to monitor the flux for an hour before and some hours after burst onset. Two minutes after it ended, HEAO 1 A-2 detected a faint resurgence of 2-10 keV flux, rising to a peak ~7 minutes after burst onset, followed by irregular emission with a best-fit decay time of ½ hr. The position of the source of the extended flux was consistent with that of the burst and was probably not from a serendipitous transient. We estimated that the entire afterglow radiated between 3% and 30% of the >1 keV energy radiated during the burst. In this paper, we present the 2-300 keV HEAO 1 A-2 and A-4 light curves and spectra from GRB 780506 and its apparent ~1 keV afterglow.
Position and enantioselective dihydroxylation of 2-hydroxymethyl- and 2-hydroxyethyl-1,3-butadiene derivatives using bis-cinchona alkaloid catalysts

Abstract The asymmetric dihydroxylation of p-methoxybenzoate esters of p-methoxyphenyl ethers of 2-hydroxymethyl-1,3-butadienes or 2-hydroxyethyl-1,3-butadienes proceeds with excellent position and enantioselectivity using bis-cinchona alkaloid catalysts. The regioselectivity of these reactions is strongly influenced by binding interactions between the aromatic ether or ester group and the catalyst as predicted from a previously proposed transition state model.
Effects of Strong Magnetic Fields on Neutron Star Structure

We study static neutron stars with poloidal magnetic fields and a simple class of electric current distributions consistent with the requirement of stationarity. For this class of electric current distributions, we find that magnetic fields are too large for static configurations to exist when the magnetic force pushes a sufficient amount of mass off-center that the gravitational force points outward near the origin in the equatorial plane. (In our coordinates an outward gravitational force corresponds to ∂ ln gtt/∂r > 0, where t and r are respectively time and radial coordinates and gtt is coefficient of dt2 in the line element.) For the equations of state (EOSs) employed in previous work, we obtain configurations of higher mass than had been reported; we also present results with more recent EOSs. For all EOSs studied, we find that the maximum mass among these static configurations with magnetic fields is noticeably larger than the maximum mass attainable by uniform rotation, and that for fixed values of baryon number the maximum mass configurations are all characterized by an off-center density maximum.
Effect of Enteric Nonnutrient Infusions on Motor Patterns in Neurally Intact and Neurally Isolated Canine Jejunum

Previous work in our laboratory has shown that nonnutrient mechanical factors initiate changes in motility patterns in local and remote regions of the small intestine. Our aims were to determine how isolated duodenal and jejunoileal nonnutrient infusions alter interdigestive motor patterns locally and distantly and whether these effects are neurally mediated. Ten dogs were prepared with duodenal and proximal jejunal infusion and manometry catheters and a proximal jejunal diverting cannula. Five of these dogs served as neurally intact controls (Group 1) and five also underwent in situ neural isolation of the entire jejunoileum (Group 2: extrinsic denervation; disruption of enteric myoneural continuity with duodenum). After recovery, nonnutrient infusions at 0-15 ml/min for 5 hr into proximal duodenum or jejunum did not consistently affect cycling of the migrating motor complex (MMC). The period and duration of individual phases of the MMC and time to first phase III after the start of infusion were similar in both groups. In Group 2, duodenal characteristics (period and duration of phase II, time to first phase III) increased slightly with increasing rates of jejunal but not duodenal infusion. Motility indices, although greater in Group 2, were not altered by enteric infusions. Differing rates of nonnutrient enteric flow limited to duodenum or jejunoileum did not affect markedly local or distant motor patterns. Alterations in interdigestive motility patterns by postprandial nonnutrient intraluminal content are not mediated directly by intraluminal flow.
Hydrocortisone-mediated regulation of gene expression in embryonic neural retina: induction of glutamine synthetase.

Abstract Functional differentiation in the embryonic chick neural retina is marked by a sharp increase in the accumulation of glutamine synthetase (GS). Hydrocortisone and related 11-β-hydroxy corticosteroids induce prematurely GS in the embryonic retina. The induction involves gene expression which results in increased rate of GS synthesis and accumulation. Properties of hydrocortisone receptors in retina cytosol are described and compared with those from other embryonic tissues. Binding of hydrocortisone-receptor complexes to retina nuclei was studied to estimate the number of nuclear binding sites related to GS induction. GS is not inducible in dispersed retina cells; inducibility for this enzyme depends on retinotypic organization of the cells. It is suggested that histotypic cell contacts in the embryonic retina are involved in the mechanisms which control induction by the steroid of this gene-controlled expression characteristic of the differentiation of these cells.
A spontaneous bicyclization facilitates a synthesis of (−)-hispidospermidin

A concise, enantiospecific synthesis of the phospholipase C inhibitor (−)-hispidospermidin (1) has been achieved by approximating the architecture of a reactive intermediate that may lie on the biosynthetic pathway leading to this natural product. Two compounds derived from (R)-(+)-pulegone were joined by a highly diastereoselective carbonyl addition. A proximity-facilitated, acid-induced bicyclization of spiro[4.5]deca-1,7-diene 29 gave rise to the tetracyclic framework of 1 and was the key transformation in this synthesis.
Bargaining rules of thumb

Abstract A steady-state, random-matching game model is used to described bargaining in a large population, where bargainers choose rules of thumb to apply across the board in a class of bargaining situations they face. The unique population equilibrium rule distributions are computed for certain cases of the model. These are then used in an exercise to analyze the relationship between a society's wealth and the relative frequency of haggled transactions in the society.