cssi/SciSciGPT-SciSciNet huggingface dataset:
A 2-D gel electrophoresis DNA image analysis algorithm with automatic thresholding

Polymerase chain reaction (PCR) and gel electrophoresis are two widely used techniques for genetic studies that require the bench scientist to perform many tedious manual steps. Advances in automation are making these techniques more accessible, but detection and image analysis still remain labor-intensive. Although several commercial software packages are now available, DNA image analysis still requires some intervention by the user, and thus a certain level of image processing expertise. To allow researchers to speed up their analyses and obtain more repeatable results, we present a fully automated image analysis system for DNA or protein studies with high accuracy. The proposed system is based mainly on four steps: automatic thresholding, shifting, filtering, and processing. The automatic thresholding that is used to equalize the gray values of the gel electrophoreses image background is one of the key and novel operations in this algorithm. An enhancement is also used to improve poor quality images that have faint DNA bands. Experimental results show that the proposed method eliminates defects due to noise for good and average quality gel electrophoresis images, while it also improves the appearance of poor quality images.
Optimal Control With Chebyshev Minimax Performance Index

Optimal control of dynamic systems with minimax type performance index, discussing application of proposed method of solution
Scope and Mechanism of the Pt-Catalyzed Enantioselective Diboration of Monosubstituted Alkenes

The Pt-catalyzed enantioselective diboration of terminal alkenes can be accomplished in an enantioselective fashion in the presence of chiral phosphonite ligands. Optimal procedures and the substrate scope of this transformation are fully investigated. Reaction progress kinetic analysis and kinetic isotope effects suggest that the stereodefining step in the catalytic cycle is olefin migratory insertion into a Pt–B bond. Density functional theory analysis, combined with other experimental data, suggests that the insertion reaction positions platinum at the internal carbon of the substrate. A stereochemical model for this reaction is advanced that is in line both with these features and with the crystal structure of a Pt–ligand complex.
Intramolecular azide-alkyne [3 + 2] cycloaddition: versatile route to new heterocyclic structural scaffolds

Investigating the relatively unexplored intramolecular version of the azide-alkyne [3 + 2] cycloaddition, the present studies demonstrate the utility of the above reaction in the synthesis of a variety of as yet unreported heterocyclic structural scaffolds. The approach involved initial installation of strategic azide and alkyne moieties on a common structural framework, followed by their intramolecular cycloaddition studies. The pivotal azidoalkyne intermediates were efficiently accessed from a variety of easily available starting materials such as olefins, epoxides, amino acids, amino alcohols, ketones etc. The key reactions for incorporation of the azide functionality into the desired framework involved azidolysis of epoxides, displacement of hydroxy groups with azide nucleophiles, and diazo transfer on amine. Attachment of the desired alkyne functionalities was accomplished by either N-, or, O-alkylation with appropriate propargylic halides. The azidoalkynes thus prepared underwent smooth intramolecular cycloaddition, resulting in a variety of novel triazolooxazine and triazolopyrazine derivatives. Interestingly, unlike in the intermolecular version, metal catalysis was not necessary for the performance of the above cycloadditions. It is expected that the results from the present studies and its further extension will provide a potentially fertile pathway to a variety of unique chemical entities of structural and biological significance.
Free Energy and Complexity of Spherical Bipartite Models

We investigate both free energy and complexity of the spherical bipartite spin glass model. We first prove a variational formula in high temperature for the limiting free energy based on the well-known Crisanti–Sommers representation of the mixed \(p\)-spin spherical model. Next, we show that the mean number of local minima at low levels of energy is exponentially large in the size of the system and we derive a bound on the location of the ground state energy.
Pure subrings of regular rings are pseudo-rational

We prove a generalization conjectured by Aschenbrenner and Schoutens (2003) of the Hochster-Roberts-Boutot-Kawamata Theorem: let R → S be a pure homomorphism of equicharacteristic zero Noetherian local rings. If S is regular, then R is pseudo-rational, and if R is moreover Q-Gorenstein, then it is pseudo-log-terminal.
Tandem organometallic addition reactions to N-methoxy-ureas and urethanes in the preparation of unsymmetrical and symmetrical ketones

Abstract The use of the novel reagents 1a–c for the synthesis of ketones in a one pot reaction is described. An interesting leaving group effect was discovered in the fragmentation of the proposed complexes 2 to the intermediate N-methoxyamides 3 .
Does culture influence IPO underpricing

Abstract This paper examines how cultural differences influence cross-sectional variation in IPO underpricing across 39 countries. We conjecture that cultural difference across geographic boundaries will influence the acceptance of and the expectations for IPO underpricing. Cross-sectional differences in culture are measured using Hofstede's six cultural dimensions. Our analysis shows that high power distance and high long term orientation are significantly associated with higher IPO underpricing. We also show that underpricing is significantly lower in countries characterized by high uncertainty avoidance. When the model is expanded to include legal origin, market based and corporate governance variables, the three cultural factors remain significant. Our findings provide further evidence that culture impacts capital market returns. Overall, our finding that culture impacts IPO underpricing, suggests important implications for policy makers and investors.
Elected Versus Appointed Policymakers: Evidence from City Treasurers

Abstract This paper investigates whether the method of selecting public officials affects policy making. I compare the policy choices of bureaucrat city treasurers and politician city treasurers, who are selected and held accountable in very different ways. The analysis draws on rich data from California to examine whether cities with appointed or elected city treasurers pay lower costs to borrow. The results demonstrate that having appointive treasurers reduces a city’s cost of borrowing by 19–31 percent. Holding officials directly accountable to voters can result in lower levels of performance in complex policy areas.
Photoionization of clustered halos by the first stars

We present numerical simulations of the photoevaporation of cosmological halos clustered around a 120 M⊙ primordial star, confining our study to structures capable of hosting Population III star formation. The calculations include self‐consistent multifrequency conservative transfer of UV photons together with nine‐species primordial chemistry and all relevant radiative processes. The ultimate fates of these halos varies with central density and proximity to the central source but generally fall into one of four categories. Diffuse halos with central densities below 2–3 cm−3 are completely ionized and evaporated by the central star anywhere in the cluster. More evolved halo cores at densities above 2000 cm−3 are impervious to both ionizing and Lyman‐Werner flux at most distances from the star and collapse of their cores proceeds without delay. Radiative feedback in halos of intermediate density can be either positive or negative, depending on how the I‐front remnant shock both compresses and deforms the c...
Condition of self-duality for SU(2) gauge fields on Euclidean four-dimensional space

The condition of self-duality for a SU(2) gauge field on Euclidean four-dimensional flat space is integrated once to obtain Laplace-like equations for three real variables or for variables one real and one complex. A special case of the latter reduces to the Corrigan-Fairlie-Wilczek-'t Hooft Ansatz.
Dynamic Response Analysis of DC–DC Converter With Supercapacitor for Direct Borohydride Fuel Cell Power Conditioning System

The direct borohydride fuel cell (DBFC) is directly fed sodium borohydride as a fuel and hydrogen peroxide as an oxidant. The output voltage of the DBFC varies with respect to current demand. Therefore, it requires a dc-dc converter for a regulated output voltage. The dc-dc converter should be designed considering both the impact of the fuel cell and load disturbances to achieve wide range voltage regulation. This paper analyzes the impact of the DBFC impedance on the dc-dc converter. Based on the converter's small signal model including the DBFC impedance, the boost converter was evaluated. Impacts of the voltage and current control loops on the boost converter were investigated. Improved response time and stability of the DBFC dc-dc converter were observed by adding a supercapacitor between the DBFC and the dc-dc converter. Finally, two converter controllers, a nonlinear feedforward controller and a state feedback controller are proposed for further improvement of the dc-dc converter response time. A prototype 20-W dc-dc converter was built and tested to show the response improvement of the proposed analysis and control scheme.
SnTe Nanocrystals: A New Example of Narrow-Gap Semiconductor Quantum Dots

A solution-phase synthesis of monodisperse SnTe nanocrystals via the reaction of bis[bis(trimethylsilyl)amino]tin(II) with trioctylphosphine telluride in oleylamine is demonstrated. The obtained SnTe nanocrystals are single-crystalline particles with a cubic rock-salt crystal structure. The size of the SnTe nanocrystals can be precisely tuned in the range of 4.5−15 nm by tailoring the reaction temperature and stabilizer concentration. These SnTe nanocrystals exhibit size-tunable band gap energies of 0.38−0.8 eV. The narrow size-distributions allow assembling SnTe nanocrystals into 3-dimensional superlattices.
Distributed out-bound load balancing in inter-AS routing by random matchings

The Internet is composed of a collection of inter-connected and self-administered Autonomous Systems (ASms). Inter-AS routing is accomplished by having neighboring ASms exchange reachability information via the Border Gateway Protocol. An AS is said to be a transit AS if it allows traffic from other ASms to cross through it. In particular, transit ASms provide transit services for traffic between customer and provider ASms. In this article, we focus on maximizing the utilization of resources at transit ASms. In particular, inter-AS links have been shown to be a bottleneck. To make better use of inter-AS links, we consider the problem of balancing the load among inter-AS links. We refer to this problem as the Balanced-Flow Assignment ProbleM (B-FAPM). We show that the B-FAPM is NP-hard, and thus, likely intractable. We then present a heuristic protocol, the Balanced-Flow Assignment ProtocoL (B-FAPL), that balances the out-bound traffic loads on inter-AS links. We show via simulation that the B-FAPL effectively balances outgoing traffic over inter-AS links. Our solution is fully distributed and uses random matchings to assign in-bound flows to out-bound inter-AS links.
The shape of the renormalized trajectory in the two-dimensional O(N) non-linear sigma model

Abstract The renormalized trajectory in the multi-dimensional coupling parameter space of the two-dimensional O (3) non-linear sigma model is determined numerically under δ-function block spin transformations using two different Monte Carlo renormalization group techniques. The renormalized trajectory is compared with the straight line of the fixed point trajectory (fixed point action) which leaves the asymptotically free ultraviolet fixed point of the critical surface in the orthogonal direction. Our results show that the renormalized trajectory breaks away from the fixed point trajectory in a range of the correlation length around ξ ≈ 3–7, flowing into the high temperature fixed point at ξ = 0. The analytic large N calculation of the renormalized trajectory is also presented in the coupling parameter space of the most general bilinear Hamiltonians. The renormalized trajectory in the large N approximation exhibits a similar shape as in the N = 3 case, with the sharp break occurring at a smaller correlation length of ξ ≈ 2–3.
Fast inverse dynamics computation in real-time robot control

Abstract In this paper, two fast algorithms for the inverse dynamics computation in real-time robot control are developed by using simple Lagrange-Euler formulation. The high computational efficiency of the proposed algorithms can make the inverse dynamics computation of any practical robot to be implemented on a current microcomputer in real-time. As compared with other existing algorithms, the algorithms proposed in this paper are, computationally, the fastest of all existing algorithms for robot dynamics computation.
Seeking Assurances When Taking Action: Legal Systems, Social Trust, and Starting Businesses in Emerging Economies:

This study examines how institutional conditions provide assurances founders seek when creating businesses. Classical theories predict legal institutions promote supportive conditions that foster business creation. We develop an alternative theory for why this relationship is not as straightforward in emerging economies. In these regions, people may be discouraged from taking entrepreneurial action because of the difficulties in accessing legal protections efficiently. We also introduce theory regarding the moderating role of generalized social trust because of its normative influences on business creation. We argue that generalized trust in strangers exerts positive moderating effects on the direct relationship between legal protections and entrepreneurship. The findings from our multilevel analysis of 30 emerging economies are consistent with our theory. Our work advances a new framework for how entrepreneurs cope with uncertain business conditions in emerging economies where informal, normative social structures offer more privately oriented safeguards than do formal, publicly oriented institutions. Our study also reconnects macro-institutional theories with individual-level accounts of entrepreneurship.
Open-string vertex algebras, tensor categories and operads

We introduce notions of open-string vertex algebra, conformal open-string vertex algebra and variants of these notions. These are “open-string-theoretic”, “noncommutative” generalizations of the notions of vertex algebra and of conformal vertex algebra. Given an open-string vertex algebra, we show that there exists a vertex algebra, which we call the “meromorphic center,” inside the original algebra such that the original algebra yields a module and also an intertwining operator for the meromorphic center. This result gives us a general method for constructing open-string vertex algebras. Besides obvious examples obtained from associative algebras and vertex (super)algebras, we give a nontrivial example constructed from the minimal model of central charge Open image in new window We establish an equivalence between the associative algebras in the braided tensor category of modules for a suitable vertex operator algebra and the grading-restricted conformal open-string vertex algebras containing a vertex operator algebra isomorphic to the given vertex operator algebra. We also give a geometric and operadic formulation of the notion of grading-restricted conformal open-string vertex algebra, we prove two isomorphism theorems, and in particular, we show that such an algebra gives a projective algebra over what we call the “Swiss-cheese partial operad.”
Asset prices and real investment

Abstract Firm investment activity and firm characteristics, particularly the market-to-book ratio or q, are functions of the state of the economy and therefore contain information about the dynamic behavior of stock returns. This paper develops a model of a production economy in which real investment is irreversible and subject to convex adjustment costs. During low-q (high-q) periods when the irreversibility constraint (constraint on the rate of investment) is binding, conditional volatility and expected returns on one hand, and market-to-book ratios on the other, should be negatively (positively) related. Empirical tests based on industry portfolios support these predictions for conditional volatility but not for expected returns.
A Middle Stone Age Paleoscape near the Pinnacle Point caves, Vleesbaai, South Africa

Abstract Open-air Middle Stone Age (MSA) contexts in southern Africa have received relatively little research attention compared to caves/rock-shelters. MSA caves/rock shelters can provide long sequences of MSA behaviors dominated by residential activities in circumscribed contexts but most procurement activities occurred on the landscape in uncircumscribed space. We have a limited understanding of these activities at present, making studies of open-air sites crucial. To alleviate this bias, the South African Coast Paleoclimate, Paleoenvironment, Paleoecology, Paleoanthropology (SACP4) project expanded its research scope to include MSA archaeology from open-air contexts. We report on a series of MSA open-air assemblages that are exposed on ancient land surfaces suggestive of intact paleosols at Vleesbaai and Visbaai, South Africa. Importantly, these sites occur in close proximity to the long cave/rock shelter sequences at Pinnacle Point. This presents the novel potential to study evidence of MSA behavior in closed and open settings where their proximity to each other approximates the typical hunter–gatherer daily foraging radius documented in ethnography. We present a fabric and technological analysis of MSA stone tool assemblages from three “Areas”. Analysis of total-station piece plotting of artifact bearing/plunge suggests that the lithic assemblages have undergone limited post-depositional disturbance. The technological analysis and exploratory comparisons between these open-air assemblages and MSA cave and rock shelter contexts at Pinnacle Point Cave 13B and 9, and Cape St. Blaize Cave suggest that the quartzite artifacts from Vleesbaai were procured from locally available sources and may have been field processed there before being transported elsewhere, perhaps to the caves/rock shelters. Further, the analysis suggests a dichotomous pattern of retouched tool discard, where quartzite tools are discarded similarly across the landscape. In contrast, non-quartzite tools may have been made primarily at the cave sites, and discarded or lost more frequently on the landscape.
On the emergence of exchange and mediation in a production economy

In this paper we simulate the behavior of a population of boundedly rational agents in a two good economy where all agents can spend their time budget for the production of one or both goods or trading. Agents update their strategies according to a simple imitation type learning rule with noise. It is shown that in several different setups both direct trade and trade via mediators who specialize in trading can emerge. Both increasing returns to scale in production and heterogeneity of production technologies facilitates the development of trade. For heterogeneous production technologies we can also observe the transition from a pure production economy via direct trade to an economy with mediated trade.
Enriched Reedy categories

This research was partially conducted during the period the author was employed by the Clay Mathematics Institute as a Liftoff Fellow.
Negative conductance in semiconductors

Until recently, investigators have been frustrated in their attempts at applying microwave and millimeter-wave frequencies to semiconductor devices. During the last few years, the discovery of avalanche transit-time and Gunn effects in bulk semiconductors has been met with overwhelming enthusiasm. The successful fabrication of models presently utilizing these negative-conductance phenomena has given these high-frequency devices an optimistic outlook for the future.
Hydrodynamical models of presolar nebula formation

Theories of solar system formation often presuppose the existence of the protosun and an accompanying preplanetary nebula. Numerical three-dimensional calculations are presented which demonstrate the possibility of formation of a co-orbital, triple protostellar system, which is unstable to decay to a binary and an ejected single star. The calculations are used to construct a plausible scenario for presolar nebula formation based on a hierarchy of collapse and fragmentation. While this sequence is unlikely to produce many single stars, it remains a possible sequence for the formation of the presolar nebula.
Total variation cutoff in birth-and-death chains

The cutoff phenomenon describes a case where a Markov chain exhibits a sharp transition in its convergence to stationarity. Diaconis [Proc Natl Acad Sci USA 93(4):1659–1664, 1996] surveyed this phenomenon, and asked how one could recognize its occurrence in families of finite ergodic Markov chains. Peres [American Institute of Mathematics (AIM) Research Workshop, Palo Alto. http://www.aimath.org/WWN/mixingtimes, 2004] noted that a necessary condition for cutoff in a family of reversible chains is that the product of the mixing-time and spectral-gap tends to infinity, and conjectured that in many settings, this condition should also be sufficient. Diaconis and Saloff-Coste [Ann Appl Probab 16(4):2098–2122, 2006] verified this conjecture for continuous-time birth-and-death chains, started at an endpoint, with convergence measured in separation. It is natural to ask whether the conjecture holds for these chains in the more widely used total-variation distance. In this work, we confirm the above conjecture for all continuous-time or lazy discrete-time birth-and-death chains, with convergence measured via total-variation distance. Namely, if the product of the mixing-time and spectral-gap tends to infinity, the chains exhibit cutoff at the maximal hitting time of the stationary distribution median, with a window of at most the geometric mean between the relaxation-time and mixing-time. In addition, we show that for any lazy (or continuous-time) birth-and-death chain with stationary distribution π, the separation 1 − pt(x, y)/π(y) is maximized when x, y are the endpoints. Together with the above results, this implies that total-variation cutoff is equivalent to separation cutoff in any family of such chains.
Small molecules that modulate quorum sensing and control virulence in Pseudomonas aeruginosa.

Bacteria use small molecule signals to access their local population densities in a process called quorum sensing (QS). Once a threshold signal concentration is reached, and therefore a certain number of bacteria have assembled, bacteria use QS to change gene expression levels and initiate behaviors that benefit the group. These group processes play central roles in both bacterial virulence and symbiosis and can have significant impacts on human health, agriculture, and the environment. The dependence of QS on small molecule signals has inspired organic chemists to design non-native molecules that can intercept these signals and thereby perturb bacterial group behaviors. The opportunistic pathogen Pseudomonas aeruginosa has been the target of many of these efforts due to its prevalence in human infections. P. aeruginosa uses at least two N-acyl l-homoserine lactone signals and three homologous LuxR-type receptors to initiate a range of pathogenic behaviors at high cell densities, including biofilm formati...
The LHC phenomenology of vectorlike confinement

We investigate in detail the LHC phenomenology of “vectorlike confinement”, where the Standard Model is augmented by a new confining gauge interaction and new light fermions that carry vectorlike charges under both the Standard Model and the new gauge group. If the new interaction confines at the TeV scale, this framework gives rise to a wide range of exotic collider signatures such as the production of a vector resonance that decays to a pair of collider-stable charged massive particles (a “di-CHAMP” resonance), to a pair of collider-stable massive colored particles (a “di-R-hadron” resonance), to multiple photons, Ws and Zs via two intermediate scalars, and/or to multi-jet final states. To study these signals at the LHC, we set up two benchmark models: one for the di-CHAMP and multi-photon signals, and the other for the di-R-hadron and multi-jet signals. For the di-CHAMP/multi-photon model, Standard Model backgrounds are negligible, and we show that a full reconstruction of the spectrum is possible, providing powerful evidence for vectorlike confinement. For the di-R-hadron/multi-jet model, we point out that in addition to the di-R-hadron signal, the rate of the production of four R-hadrons can also be sizable at the LHC. This, together with the multi-jet signals studied in earlier work, makes it possible to single out vectorlike confinement as the underlying dynamics.
ASYMPTOTICS OF GREEDY ENERGY POINTS

For a symmetric kernel k: X x X → ℝ U {+∞} on a locally compact metric space X, we investigate the asymptotic behavior of greedy k-energy points {a i } ∞ 1 for a compact subset A C X that are defined inductively by selecting a 1 ∈ A arbitrarily and a n+1 so that Σ n i=1 k(a n+l1 ,a i ) = inf x∈A Σ n i =1 k(x,a i ). We give sufficient conditions under which these points (also known as Leja points) are asymptotically energy minimizing (i.e. have energy Σ N i≠j k(a i , aj) as N → ∞ that is asymptotically the same as e(A, N) := min{Σ i≠j k(x i , x j ): x 1 ,...,x N ∈ A}), and have asymptotic distribution equal to the equilibrium measure for A. For the case of Riesz kernels k s (x, y) := |x ― y| ―s , s > 0, we show that if A is a rectifiable Jordan arc or closed curve in RP and s > 1, then greedy k s -energy points are not asymptotically energy minimizing, in contrast to the case s 1.) Additional results are obtained for greedy k s -energy points on a sphere, for greedy best-packing points (the case s = ∞), and for weighted Riesz kernels. For greedy best-packing points we provide a simple counterexample to a conjecture attributed to L. Bos.
CAMINA p-groups that are generalized Frobenius complements

Let P be a Camina p-group that acts on a group Q in such a way that \({\mathbf{C}_P(x) \subseteq P'}\) for all nonidentity elements \({x \in Q}\). We show that P must be isomorphic to the quaternion group Q8. If P has class 2, this is a known result, and this paper corrects a previously published erroneous proof of the general case.
Acute appendicitis caused by acute myeloid leukemia

A 57-year-old man with a seven-month history of refractory anemia with excess blasts (RAEB-2), recently transformed to acute myeloid leukemia (AML) presented with a 3-day history of lower abdominal pain, nausea, and constipation. There was no fever or vomiting. Physical examination revealed tenderness in his abdominal bilateral lower quadrants. CAT scan revealed a thickened appendix and periappendiceal stranding. The liver, spleen, pancreas, adrenal glands, and kidneys were normal. The gall bladder was previously removed and was not visible. His peripheral blood count showed white blood cell count of 2.3 × 109/L with granulocytic left shift and few blasts (4%), hemoglobin of 8.3 g/dL, and platelet count of 34 × 109/L. An acute appendicitis was suspected and a laparoscopic appendectomy was performed. Visual inspection of the peritoneal cavity during the procedure was essentially unremarkable. The appendix appeared to be inflamed and grossly showed no adhesions. Histologic sections (Figure 1) revealed extensive proliferation of hematopoietic cells involving predominantly serosa and periappendiceal tissue. There were clusters and aggregates of large immature precursor cells with irregular nuclear contours, delicate chromatin, distinct nucleoli, and scant to moderately abundant cytoplasm. Rare islands of erythroid precursor cells were present. The mucosa, submucosa, and muscularis propria of the appendix were histologically unremarkable. Immunohistochemical stains showed the large precursor cells were weakly positive for myeloperoxidase antigen, and partially positive for CD68 (PGM-1) and CD163. Scattered CD34- and/or CD117-positive blasts were present, though majority of the large precursor cells were negative. Few lymphoid aggregates containing mixed CD20-positive B cells and CD3-positive T cells were noted. A diagnosis of appendix involved by AML was rendered. Figure 1 (A) Cellular infiltration involving serosa and periappendiceal tissue. Hematoxylin and eosin, 4×. (B) Hematopoietic cells with sheets of large immature precursor cells. Hematoxylin and eosin, 40×. (C) Immunohistochemical stain for myeloperoxidase. ... Acute appendicitis due to involvement by acute leukemia is exceedingly rare 1–3. Being aware of this possibility is very important in the prompt diagnosis and management of these patients who may present symptoms mimicking acute appendicitis.
A Note on Stress-Tensors, Conservation and Equations of Motion

Some unusual relations between stress tensors, conservation and equations of motion are briefly reviewed.
Substance Abuse—A Suitable Case for Testing?

The case for the employer′s right to test for substance abuse is set out. Abuse is an ever‐present and expensive problem, and screening should be seen as comparable to medical assessments for suitability of employment in particular categories of work or hazardous environments. Prevention of abuse requires early recognition of those at risk and appropriate assistance. Guidelines are offered on when and how to test.
Turbulent comptonization in black hole accretion disks

In the innermost regions of radiation pressure-supported accretion disks, the turbulent magnetic pressure may greatly exceed that of the gas. If this is the case, it is possible for bulk Alfvenic motions driven by the magnetorotational instability (MRI) to surpass the electron thermal velocity. Bulk, rather than thermal, Comptonization may then be the dominant radiative process that mediates gravitational energy release. For sufficiently large turbulent stresses, we show that turbulent Comptonization produces a significant contribution to the far-UV and X-ray emission of black hole accretion disks. The existence of this spectral component provides a means of obtaining direct observational constraints on the nature of the turbulence itself. We describe how this component may affect the spectral energy distributions and variability properties of X-ray binaries and active galactic nuclei (AGN).
A glycoprotein in the accessory cell of the echinoid ovary and its role in vitellogenesis

A high-molecular-weight glycoprotein with a sedimentation coefficient of 22.6 has been isolated and characterized from the accessory cells in the previtellogenic ovary of the echinoid Dendraster excentricus. This glycoprotein is similar to the major yolk glycoprotein of the mature egg in its electrophoretic mobility under non-denaturing conditions, high mannose-type glycan, amino acid composition, constitutive glycopeptides, and immunological determinants. Previous histological and electron microscopical analyses led to the hypothesis that vitellogenesis involves a translocation of material from the accessory cell in the ovary to the oocyte. Because of the close similarities of the accessory cell glycoprotein to the yolk glycoprotein of the mature egg, we conclude that the glycoprotein in the accessory cell is a precursor to the major glycoprotein of the egg yolk. This conclusion is further supported by our additional finding that the accessory cell of another echinoid, Strongylocentrotus purpuratus, also contains a high-molecular-weight (24 S) glycoprotein which shows similarities to the yolk glycoprotein of the mature egg in the carbohydrate moiety and the constitutive glycopeptides.
DSP implementation of the retinex image enhancement algorithm

The Retinex is a general-purpose image enhancement algorithm that is used to produce good visual representations of scenes. It performs a non-linear spatial/spectral transform that synthesizes strong local contrast enhancement and color constancy. A real-time, video frame rate implementation of the Retinex is required to meet the needs of various potential users. Retinex processing contains a relatively large number of complex computations, thus to achieve real-time performance using current technologies requires specialized hardware and software. In this paper we discuss the design and development of a digital signal processor (DSP) implementation of the Retinex. The target processor is a Texas Instruments TMS320C6711 floating point DSP. NTSC video is captured using a dedicated frame-grabber card, Retinex processed, and displayed on a standard monitor. We discuss the optimizations used to achieve real-time performance of the Retinex and also describe our future plans on using alternative architectures.
Turbulent Transport on the Endwall in the Region Between Adjacent Turbine Blades

The complex three-dimensional flow in the endwall region near the base of a turbine blade has an important impact on the local heat transfer. The initial horseshoe vortex, the passage vortex, and resulting corner vortices cause large variations in heat transfer over the entire endwall region. Due to these large surface gradients in heat transfer, conventional measurement techniques generally do not provide in accurate determination of the local heat transfer coefficients. In the present study the heat/mass transfer analogy is used to examine the local transport coefficients for two different endwall boundary layer thicknesses and two free-stream Reynolds numbers. A linear turbine blade cascade is used in conjunction with a removable endwall plate. Napthalene (C{sub 10}H{sub 8}) is cast into a mold on the plate and the rate of naphthalene sublimation is determined at 6,000+ locations on the simulated endwall by employing a computer-aided data acquisition system. This technique allows one to obtain detailed contour plots of the local convection coefficient over the entire endwall. By examining the mass transfer contours, it is possible to infer information on three-dimensional flow in the passage between the blades. Extremely high transport coefficients on the endwall indicate locations of potential overheating and failuremore » in actual turbine.« less
Design of crystalline molecular networks with charge-assisted hydrogen bonds

Empirical guidelines for steering molecular assembly into prescribed crystal architectures via hydrogen bonding continue to emerge, with recent developments demonstrating that charge-assisted hydrogen bonds introduce both strength and compliance that can facilitate solid state design.
Porphyrins with exocyclic rings. Part 20: Synthesis and spectroscopic characterization of porphyrins with fused 2,1,3-benzoxadiazole and 2,1,3-benzoselenadiazole moieties

Abstract Porphyrins with fused 2,1,3-benzoxadiazole and 2,1,3-benzoselenadiazole units were prepared by the ‘3+1’ MacDonald-type methodology. 4-Nitro-2,1,3-benzoxadiazole, 6-chloro-4-nitro-2,1,3-benzoxadiazole and 4-nitro-2,1,3-benzoselenadiazole condensed with isocyanoacetates in the presence of the non-nucleophilic base DBU to give tricyclic pyrrole derivatives in excellent yields. Further cleavage of the ester moieties and decarboxylation afforded α-unsubstituted pyrroles and these were further condensed with 2 equiv of an acetoxymethylpyrrole tert -butyl ester to give crude preparations of tripyrranes. The tert -butyl ester protective groups were cleaved with TFA and following dilution with dichloromethane, ‘3+1’ condensation with a pyrrole dialdehyde, and oxidation with ferric chloride, the heterocyclic ring fused porphyrins were obtained in moderate yields. The yields were lower than expected because of difficulties in preparing required tripyrranes due to the reduced reactivity of the pyrrolic intermediates. The UV–vis spectra of these new porphyrin systems were highly modified showing broadened split Soret bands. In addition, the nickel(II), copper(II) and zinc complexes gave unusual UV–vis spectra with weakened split Soret bands and strong Q-type absorptions above 600 nm. These modified structures show some potential for applications as photosensitizers in photodynamic therapy.
Do Government Economists Value AAEA Conferences

This article examines the importance and value of attending the annual summer conference of the Agricultural and Applied Economics Association (AAEA) by U.S. Federal government economists. A choice-based conjoint analysis of government funding of five research-facilitating resources, including travel and nontravel resources, shows that respondents have a clear preference for their government agency funding the travel-related resources over the other resources. Furthermore, using the contingent valuation method, we find that these economists would have been willing to pay $195 to $620 to have attended their last AAEA conference, with the bounds on this range depending on modeling assumptions.
Downlink Noncoherent Cooperation without Transmitter Phase Alignment

Multicell joint processing can mitigate inter-cell interference and thereby increase the spectral efficiency of cellular systems. Most previous work has assumed phase-aligned (coherent) transmissions from different base transceiver stations (BTSs) so that the signals superpose coherently at each receiver, which is difficult to achieve in practice. In this work, a noncoherent cooperative transmission scheme for the downlink is studied, which does not require phase alignment. The focus is on jointly serving two users in adjacent cells sharing the same resource block. The two BTSs partially share their messages through a backhaul link, and each BTS can transmit a superposition of two codewords, one for each receiver. Each receiver decodes its own message, and treats the signals for the other receiver as background noise. With narrowband transmissions the achievable rate region and maximum achievable weighted sum rate are characterized by optimizing the power allocation (and the beamforming vectors in the case of multiple transmit antennas) at each BTS between its two codewords. For a wideband (multicarrier) system, a dual formulation of the optimal power allocation problem across sub-carriers is presented, which can be efficiently solved by numerical methods. Results show that the proposed cooperation scheme can improve the sum rate substantially in the low to moderate signal-to-noise ratio (SNR) range.
The Application of UV Raman Spectroscopy for the Characterization of Catalysts and Catalytic Reactions

Ultraviolet Raman spectroscopy is a powerful tool for the characterization of solid catalysts. When the excitation wavelength is below 260 nm, the Raman peaks typically appear at shorter wavelengths than fluorescence, which would otherwise obscure the spectrum. This advantage is particularly useful for zeolite materials, which have traditionally been difficult to characterize with Raman spectroscopy. With a fluidized-bed reactor, it is possible to perform experiments with thermally and photochemically sensitive adsorbed species or even under catalytic reaction conditions, without interference from laser-induced sample decomposition. Resonance enhancement provides the opportunity to probe specific components in a heterogeneous mixture and to increase band intensities above the detection limit for weak signals. This feature is demonstrated for VOx/alumina as a function of vanadium loading and for Fe/MFI catalysts. The spectra of adsorbed benzene demonstrate the ability of resonance Raman spectroscopy to detect subtle distortions in the benzene structure. Furthermore, the UV Raman spectra of coke formed during catalytic hydrocarbon conversions are shown to be diagnostic of the coke topology.
Electronic structures and bonding of oxygen on plutonium layers

Oxygen adsorptions on $\delta $ -Pu (100) and (111) surfaces have been studied at both non-spin-polarized and spin-polarized levels using the generalized gradient approximation of density functional theory (GGA-DFT) with Perdew and Wang (PW) functionals. The center position of the (100) surface is found to be the most favorable site with chemisorption energies of 7.386 eV and 7.080 eV at the two levels of theory. The distances of the oxygen adatom from the Pu surface are found to be 0.92 A and 1.02 A, respectively. For the (111) surface non-spin-polarized calculations, the center position is also the preferred site with a chemisorption energy of 7.070 eV and the distance of the adatom being 1.31 A, but for spin-polarized calculations the bridge and the center sites are found to be basically degenerate, the difference in chemisorption energies being only 0.021 eV. In general, due to the adsorption of oxygen, plutonium 5f orbitals are pushed further below the Fermi energy, compared to the bare plutonium layers. The work function, in general, increases due to oxygen adsorption on plutonium surfaces.
Double Injection in Insulators

Double injection in insulators is analyzed taking into account that the lifetimes for the injected electrons and holes are different and vary with injection level. Assuming charge neutrality, a detailed solution is obtained for the simple model of an insulator with a single set of recombination centers filled with electrons in thermal equilibrium. The major results are: (i) There is a threshold voltage ${V}_{\mathrm{th}}$ below which the double-injection current is negligible and at which this current rises steeply with voltage. At this threshold voltage the hole transit time, ${t}_{p,\mathrm{th}}=\frac{{L}^{2}}{{\ensuremath{\mu}}_{p}{V}_{\mathrm{th}}}$, is comparable to the hole lifetime ${\ensuremath{\tau}}_{p,\mathrm{low}}$. The subscript "low" refers to the lifetime at low injection levels. The lifetime at high injection levels in this model will generally be longer. (ii) For an electron capture cross section ${\ensuremath{\sigma}}_{n}$ much smaller than the hole capture cross section ${\ensuremath{\sigma}}_{p}$, there is a negative resistance between ${V}_{\mathrm{th}}$ and ${V}_{M}\ensuremath{\approx}(\frac{{\ensuremath{\sigma}}_{n}}{{\ensuremath{\sigma}}_{p}}){V}_{\mathrm{th}}$. With increasing current, the voltage decreases from ${V}_{\mathrm{th}}$ to ${V}_{M}$. This negative resistance has its origin in an increasing hole lifetime with increasing injection level, owing to electron depopulation of the recombination centers by hole capture. (iii) At still higher currents the double-injection current-voltage characteristic is similar to that for a semiconductor at high injection levels. At sufficiently low currents the neutrality-based, double-injection solution is no longer self-consistent with respect to the neglect of space charge, and the true current is a one-carrier SCL (space-charge-limited) current which, for the simple model analyzed, is the electron SCL current for a trap-free insulator. In real insulators the one-carrier SCL current may mask the voltage threshold effect, (i) above, depending on the physical parameters of the crystal. On the other hand, under the condition specified in (ii) above, the negative resistance will always be observed. Experimentally, the negative resistance should produce either current oscillations or a hysteresis in the voltage vs current for dc applied voltages. Both effects have been widely observed in insulators and high-resistivity semiconductors. It is shown how the theory can be extended to more complicated models.
High-speed optical studies of the driving plasma in laser acceleration of flyer plates

High-speed optical methods have been used to study several characteristics of the high-temperature driving plasma in laser acceleration of flyers with optical fiber coupling. Flyer materials examined include pure aluminum and composite targets containing an insulating layer of Al2O3. Results from fast-gated spectroscopy show that silicon appears early in the plasma spectrum, indicating that the coupling fiber material plays an active role in flyer acceleration. Plasma emission persists longer and pressure broadening of discrete lines decays more slowly in the launch of composite flyers. Fast-gated spectroscopy has also been used in conjunction with very thin (“trace”) metal layers deposited in the target fabrication process to examine the depth of ablation by the driving plasma.
The room temperature conversion of nickel difluoride to hexafluoronickelate(IV) salts of alkali cations

Abstract NiF 2 was oxidized at ~20 °C, to NiF 6 2− by sunlight or ultraviolet light-irradiated F 2 in liquid anhydrous hydrogen fluoride (aHF) containing alkali hydrofluorides AF(HF) x . Quantitative formation of NiF 6 2 can be achieved with strongly basic solutions (e.g., KF:HF molar ratio ~ 1:4). Li 2 NiF 6 , which was previously unknown, is the least aHF soluble of the alkali NiF 6 2 salts, and was prepared in high purity.
Mild and direct conversion of quinoline N-oxides to 2-amidoquinolines with primary amides.

A simple, one-pot procedure is described for the direct conversion of quinoline N-oxides to α-amidoquinolines with primary amides. This methodology is complimentary to the Abramovich reaction, which is limited to the introduction of secondary amides via imidoyl chlorides. Although reaction conditions are quite similar, omission of the base is key for successful reaction with primary amides, which were found not to proceed through the intermediacy of an imidoyl chloride but rather through an acyl isocyanate.
Correlations and fluctuations, a summary of Quark Matter 2002

Abstract Results for correlations and fluctuations presented at Quark Matter 2002 are summarized. These results include Hanbury-Brown Twiss interferometry of a wide variety of species, large scale fluctuations and correlations in p t and multiplicity, and charge fluctuations and charge balance functions.
A convenient synthesis of chiral N-Boc-amino ethers as potential peptide bond surrogate units

Abstract Boron triflouride etherate and zinc triflate have been found to be effective catalysists for the synthetic route to chiral N -Boc-amino ethers via a Lewis acid-catalyzed ring-opening of N -acyl aziridines, derived from chiral amino acids.
Testing Lorentz symmetry with atoms and light

This article reports on the Fifth Meeting on CPT and Lorentz Symmetry, CPT '10, held at the end of June 2010 in Bloomington, Indiana, USA. The focus is on recent tests of Lorentz symmetry using atomic and optical physics.
Linear instability of curved free shear layers

The linear inviscid hydrodynamic stability of slightly curved free mixing layers is studied in this paper. The disturbance equation is solved numerically using a shooting technique. Two mean velocity profiles that represent stably and unstably curved free mixing layers are considered. Results are shown for cases of five curvature Richardson numbers. The stability characteristics of the shear layer are found to vary significantly with the introduction of the curvature effects. The results also indicate that, in a manner similar to the Gortler vortices observed in a boundary layer along a concave wall, instability modes of spatially developing streamwise vortex pairs may appear in centrifugally unstable curved mixing layers.
Creep behavior in TiPdNi high temperature shape memory alloy

The focus of the current effort is to characterize the viscoplastic behavior in high temperature shape memory alloys and understand the impact of creep on their actuation characteristics. For this a Ti 50 Pd 40 Ni 10 alloy was cast and hot rolled. Standard creep tests and isobaric thermal cycling tests were conducted on a custom test setup. The results from the thermomechanical tests indicate large irrecoverable strains due to creep. Varying thermally induced transformation cycling rates did not impact the transformation behavior in the SMA. From these observations, it can be suggested that the rate of thermal cycling can alter the impact of viscoplasticity on the actuators performance. However the creep behavior itself is decoupled from the transformation and does not impact the transformation or the rate independent irrecoverable strain generated.