cssi/SciSciGPT-SciSciNet huggingface dataset:
Coal energy conversion with carbon sequestration via combustion in supercritical saline aquifer water

Abstract The standard idea for deep saline aquifer sequestration is to separate carbon dioxide from a process stream, compress it, and inject it underground. However, since carbon dioxide is less dense than water, even at the high pressures found in aquifers, it is buoyant and will move towards the surface unless trapped by an impermeable seal. Also, significant energy expenditure is required to separate and compress carbon dioxide, even though neat carbon dioxide is not a desired product. These issues may be addressed by combining the idea of fast dissolution at the surface with supercritical water oxidation (SCWO). By burning coal at high pressure in supercritical water drawn from an aquifer, and then sequestering the entire pre-equilibrated effluent, all carbon from the fuel is captured, as well as all non-mineral coal combustion products including sulfur and metals. A possible block diagram of an SCWO-based electric power plant is proposed, including processes to handle salts from the aquifer brine and minerals from coal. The plant is thermodynamically modeled, using an indirectly fired combined cycle to convert energy from hot combustion products to work. This model estimates the overall thermal efficiency that can be achieved, and reveals unanticipated interactions within the plant that have significant effects on efficiency. The assumptions and results of the model highlight design challenges for an actual system.
A physics-informed data reconciliation framework for real-time electricity and emissions tracking

Abstract To encourage and guide decarbonization efforts, better tools are needed to monitor real-time CO 2 and criteria air pollutant emissions from electricity consumption, production, imports, and exports. Using real-time data from the electricity system is especially challenging for quantitative applications requiring high quality and physically consistent data. Until now, time-intensive, ad-hoc and manual data verification and cleaning strategies have been used to prepare the data for quantitative analysis. As an alternative to existing techniques, here we provide a physics-informed framework to greatly accelerate and automate data processing to enable internally consistent electric system consumption, production, import, and export data in near real-time. A key component of this framework is an optimization program to minimize the data adjustments required to satisfy energy conservation equations. The effectiveness of this method is demonstrated by applying it to the continental United States electricity network. The resulting publicly-available data set, which provides in near-real time, hourly updates on electricity generation, consumption, imports, exports and associated emissions, is the first of this nature.
Pair-regulated Klein-Nishina relativistic magnetic reconnection with applications to blazars and accreting black holes

Relativistic magnetic reconnection is a powerful agent through which magnetic energy can be tapped in astrophysics, energizing particles that then produce observed radiation. In some systems, the highest energy photons come from particles Comptonizing an ambient radiation bath supplied by an external source. If the emitting particle energies are high enough, this inverse Compton (IC) scattering enters the Klein-Nishina regime, which differs from the low-energy Thomson IC limit in two significant ways. First, radiative losses become inherently discrete, with particles delivering an order-unity fraction of their energies to single photons. Second, Comptonized photons may pair-produce with the ambient radiation, opening up another channel for radiative feedback on magnetic reconnection. We analytically study externally illuminated highly magnetized reconnecting systems for which both of these effects are important. We identify a universal (initial magnetization-independent) quasi-steady state in which gamma-rays emitted from the reconnection layer are absorbed in the upstream region, and the resulting hot pairs dominate the energy density of the inflow plasma. However, a true pair cascade is unlikely, and the number density of created pairs remains subdominant to that of the original plasma for a wide parameter range. Future particle-in-cell simulation studies may test various aspects. Pair-regulated Klein-Nishina reconnection may explain steep spectra (quiescent and flaring) from flat-spectrum radio quasars and black hole accretion disc coronae.
La poética del bolero en las novelas de Manuel Puig.

En el repertorio de la musica popular hispanoamericana, hay dos generos que han trascendido las barreras nacionales para convertirse en continua fuente de mitos comunes y modos de expresion referidos especificamente a las relaciones interpersonales: el tango y el bolero. De los dos, el bolero es el tipo de cancion que se identifica con los sentimientos romanticos mas encendidos y con la persistente esperanza del amor.
Accurate detection of RNA stem-loops in structurome data reveals widespread association with protein binding sites.

RNA molecules are known to fold into specific structures which often play a central role in their functions and regulation. In silico folding of RNA transcripts, especially when assisted with struc...
On Construction and Estimation of Stationary Mixture Transition Distribution Models

Mixture transition distribution time series models build high-order dependence through a weighted combination of first-order transition densities for each one of a specified number of lags. We present a framework to construct stationary transition mixture distribution models that extend beyond linear, Gaussian dynamics. We study conditions for first-order strict stationarity which allow for different constructions with either continuous or discrete families for the first-order transition densities given a pre-specified family for the marginal density, and with general forms for the resulting conditional expectations. Inference and prediction are developed under the Bayesian framework with particular emphasis on flexible, structured priors for the mixture weights. Model properties are investigated both analytically and through synthetic data examples. Finally, Poisson and Lomax examples are illustrated through real data applications.
Characterizing concurrency mechanisms for NVIDIA GPUs under deep learning workloads

Abstract We investigate the performance of the concurrency mechanisms available on NVIDIA’s new Ampere GPU microarchitecture under deep learning training and inference workloads. In contrast to previous studies that treat the GPU as a black box, we examine scheduling at the microarchitectural level. We find that the lack of fine-grained preemption mechanisms, robust task prioritization options, and contention-aware thread block placement policies limits the effectiveness of NVIDIA’s concurrency mechanisms. In summary, the sequential nature of deep learning workloads and their fluctuating resource requirements and kernel runtimes make executing such workloads while maintaining consistently high utilization and low, predictable turnaround times difficult on current NVIDIA hardware.
Auto-calibration Method Using Stop Signs for Urban Autonomous Driving Applications

Calibration of sensors is fundamental to robust performance for intelligent vehicles. In natural environments, disturbances can easily challenge calibration. One possibility is to use natural objects of known shape to recalibrate sensors. An approach based on recognition of traffic signs, such as stop signs, and use of them for recalibration of cameras is presented. The approach is based on detection, geometry estimation, calibration, and recursive updating. Results from natural environments are presented that clearly show convergence and improved performance.
Constrained Differential Dynamic Programming Revisited

Differential Dynamic Programming (DDP) has become a well established method for unconstrained trajectory optimization. Despite its several applications in robotics and controls, however, a widely successful constrained version of the algorithm has yet to be developed. This paper builds upon penalty methods and active-set approaches towards designing a Dynamic Programming-based methodology for constrained optimal control. Regarding the former, our derivation employs a constrained version of Bellman’s principle of optimality, by introducing a set of auxiliary slack variables in the backward pass. In parallel, we show how Augmented Lagrangian methods can be naturally incorporated within DDP, by utilizing a particular set of penalty-Lagrangian functions that preserve second-order differentiability. We demonstrate experimentally that our extensions (individually and combinations thereof) enhance significantly the convergence properties of the algorithm, and outperform previous approaches on a large number of simulated scenarios.
Task-Invariant Learning of Continuous Joint Kinematics during Steady-State and Transient Ambulation Using Ultrasound Sensing

Natural control of limb motion is continuous and progressively adaptive to individual intent. While intuitive interfaces have the potential to rely on the neuromuscular input by the user for continuous adaptation, continuous volitional control of assistive devices that can generalize across various tasks has not been addressed. In this study, we propose a method to use spatiotemporal ultrasound features of the rectus femoris and vastus intermedius muscles of able-bodied individuals for task-invariant learning of continuous knee kinematics during steady-state and transient ambulation. The task-invariant learning paradigm was statistically evaluated against a task-specific paradigm for the steady-state (1) level-walk, (2) incline, (3) decline, (4) stair ascent, and (5) stair descent ambulation tasks. The transitions between steady-state stair ambulation and level-ground walking were also investigated. It was observed that the continuous knee kinematics can be learned using a task-invariant learning paradigm with statistically comparable accuracy to a task-specific paradigm. Statistical analysis further revealed that incorporating the temporal ultrasound features significantly improves the accuracy of continuous estimations (p < 0.05). The average root mean square errors (RMSEs) of knee angle and angular velocity estimation were 7.06° and 53.1°/sec, respectively, for the task-invariant learning compared to 6.00° and 51.8°/sec for the task-specific models. High accuracy of continuous task-invariant paradigms overcome the barrier of task-specific control schemes and motivate the implementation of direct volitional control of lower-limb assistive devices using ultrasound sensing, which may eventually enhance the intuitiveness and functionality of these devices towards a "free form" control approach.
QuantifyML: How Good is my Machine Learning Model?

The efficacy of machine learning models is typically determined by computing their accuracy on test data sets. However, this may often be misleading, since the test data may not be representative of the problem that is being studied. With QuantifyML we aim to precisely quantify the extent to which machine learning models have learned and generalized from the given data. Given a trained model, QuantifyML translates it into a C program and feeds it to the CBMC model checker to produce a formula in Conjunctive Normal Form (CNF). The formula is analyzed with off-the-shelf model counters to obtain precise counts with respect to different model behavior. QuantifyML enables i) evaluating learnability by comparing the counts for the outputs to ground truth, expressed as logical predicates, ii) comparing the performance of models built with different machine learning algorithms (decision-trees vs. neural networks), and iii) quantifying the safety and robustness of models.
Hybrid gausslet/Gaussian basis sets.

We introduce hybrid gausslet/Gaussian basis sets, where a standard Gaussianbasis is added to a gausslet basis in order to increase accuracy near thenuclei while keeping the spacing of the grid of gausslets relatively large. TheGaussians are orthogonalized to the gausslets, which are already orthonormal,and approximations are introduced to maintain the diagonal property of the twoelectron part of the Hamiltonian, so that it continues to scale as the secondpower of the number of basis functions, rather than the fourth. We introduceseveral corrections to the Hamiltonian designed to enforce certain exactproperties, such as the values of certain two-electron integrals. We alsointroduce a simple universal energy correction which compensates for theincompleteness of the basis stemming from the electron-electron cusps, based onthe measured double occupancy of each basis function. We perform a number ofHartree Fock and full configuration interaction (full-CI) test calculations ontwo electron systems, and Hartree Fock on a ten-atom hydrogen chain, tobenchmark these techniques. The inclusion of the cusp correction allows us toobtain complete basis set full-CI results, for the two electron cases, at thelevel of several microHartrees, and we see similar apparent accuracy forHartree Fock on the ten-atom hydrogen chain.
Deep Agent: Studying the Dynamics of Information Spread and Evolution in Social Networks

This paper explains the design of a social network analysis framework, developed under DARPA’s SocialSim program, with novel architecture that models human emotional, cognitive, and social factors. Our framework is both theory and data-driven, and utilizes domain expertise. Our simulation effort helps understanding how information flows and evolves in social media platforms. We focused on modeling three information domains: cryptocurrencies, cyber threats, and software vulnerabilities for the three interrelated social environments: GitHub, Reddit, and Twitter. We participated in the SocialSim DARPA Challenge in December 2018, in which our models were subjected to an extensive performance evaluation for accuracy, generalizability, explainability, and experimental power. This paper reports the main concepts and models, utilized in our social media modeling effort in developing a multi-resolution simulation at the user, community, population, and content levels.
The “authenticitude” battle in action sports: A case-based industry perspective

The expanding and often unregulated status of the action sports setting has resulted in mainstream athletic companies diversifying their products in order to portray an authentic image and establish their market presence. The influx of mainstream brands has created a new paradigm in the industry and further pressure on core action sports brands regarding their competitiveness in a highly antagonistic environment. Through a descriptive case study, 13 in-person interviews were performed with a private action sports company's employees in order to examine their perceptions relative to the organization being authentic while expanding to mainstream markets. This occurred through identification of the enterprise's true identity and deconstruction of its authenticity based on participants’ responses, which were categorized in five properties (i.e., essence of enterprise, nature of offerings, effects of heritage, sense of purpose, and body of values). Varying perspectives on each of the five elements were uncovered and discussed. Outcomes illustrated the need for a new management imperative, where action sports organizations should not only comprehend the essence of originality within their identity, but also how to render consumer's perception of authenticity.
Evaluation of hybrid algorithm for analysis of scattered light using ex vivo nuclear morphology measurements of cervical epithelium

We evaluate a new hybrid algorithm for determining nuclear morphology using angle-resolved low coherence interferometry (a/LCI) measurements in ex vivo cervical tissue. The algorithm combines Mie theory based and continuous wavelet transform inverse light scattering analysis. The hybrid algorithm was validated and compared to traditional Mie theory based analysis using an ex vivo tissue data set. The hybrid algorithm achieved 100% agreement with pathology in distinguishing dysplastic and non-dysplastic biopsy sites in the pilot study. Significantly, the new algorithm performed over four times faster than traditional Mie theory based analysis.
Effect of Distance and Duration of Illumination on Retinal Ganglion Cells Exposed to Varying Concentrations of Brilliant Blue Green

Background: The objective of the study was to determine the safety parameters of using brilliant blue green (BBG) for chromovitrectomy by assessing the cytotoxicity of BBG on cultured retinal ganglion cells (RGCs) exposed to illumination. Methods: RGCs were exposed to two concentrations of BBG (0.25 and 0.5 mg/mL) under metal halide illumination at varying distances (1 and 2.5 cm), intensities (990 and 2,000 Fc), and durations (1, 5 and 15 minutes). Cell viability was assessed using the WST-1 and CellTiter 96 ® AQueous One solution cell proliferation assays. Results: Using the WST-1 assay, with high-intensity illumination, viability of RGCs ranged from 97.5±16.4% of controls with minimum BBG and light exposure (0.25 mg/mL BBG and illuminated for 1 minute at 2.5 cm distance) to 53.1±11.3% of controls with maximum BBG and light exposure (0.50 mg/mL and illuminated for 15 minutes at 1 cm distance; P < 0.01). With medium-intensity illumination, RGCs showed better viability, ranging from 95.1±7.2% of controls with minimum BBG and light exposure to 72.3±12.8% of controls with maximum BBG and light exposure. CellTiter 96 ® AQueous One assay showed similar results. Conclusion: RGCs seem to safely tolerate up to 5 minutes of exposure to 0.5 mg/mL BBG under diffuse medium-intensity illumination (990 Fc). J Clin Med Res. 2015;7(7):517-524 doi: http://dx.doi.org/10.14740/jocmr2085e
La Ciencia de los Servicios: un nuevo enfoque para la innovación en compañías de servicios

In the last months a remarkable interest for the Service Sciences, Management, and Engineering (SSME) is increasing among diverse social players. This new academic and professional discipline proposes a scientist-technical approach to the tasks that are developed in the tertiary sector ofindustry.
Love, Chaos, and Marvell's Elegy for Cromwell

AbstractAndrew Marvell's A Poem upon the Death of His Late Highness the Lord Protector represents an attempt by the poet to translate Oliver Cromwell out of the immediate political context of the Interregnum and into a more lasting tradition founded upon the mythological concepts of love and chaos. Yet these concepts were hardly untainted by politics in 1658; invocations of chaos in particular are a fixture of Civil War polemic. Depoliticizing Cromwell thus requires that Marvell first depoliticize his poetic resources. Structuring his elegy upon a dialectic of love and chaos that looks back to the pre‐Socratics, the elegist achieves both ends elegantly—but not without difficulty. The tension between the political and the mythological underlying this critically neglected poem registers the tension between political and religious commitments that defined late‐Protectorate politics as well as the career of the Lord Protector himself. (W.M.R.)
Evaluation of bone mineral density in the healthy green iguana, Iguana iguana : Correlation of dual energy x-ray absorptiometry and radiology

ABSTRACT Dual-energy x-ray absorptiometry (DEXA) was performed in ten clinically healthy green iguanas, Iguana iguana, and compared to the radiographs of the same animal. Radiographs were digitized and the optical densities of selected anatomical regions of interest, mandible, caudal vertebra, humerus, and femur, were compared to optical densities of a standard aluminum step wedge using regression analysis. Each region of interest density was then converted to millimeters of aluminum equivalents (MAE). Comparison of the MAE values to total body bone mineral content, and bone mineral density, derived by DEXA, showed femur MAE values correlated well with the total body bone mineral content of the iguana (P ≤ 0.004). This standardization of DEXA in normal iguanas provides baseline normative data for future clinical evaluations. Additionally, the development of the radiological MAE data, and the correlation of femoral MAE with bone mineral content, provides clinicians without access to DEXA another manner to ...
Abstract 4651: Urolithin A (UA) inhibits both androgen receptor and AKT signaling and prevents the progression of castration resistant prostate cancer

Current therapeutic regimens are insufficient for treating advanced and metastatic prostate cancer. Compelling evidence suggest existence of concomitant aberrations in both activation of Androgen Receptor (AR) and Protein Kinase-B (AKT) signaling pathway in advanced castration resistant prostate cancer (CRPC). Hence, simultaneous inhibition of both AR and AKT appears to be an effective strategy for the prevention and treatment of CRPC. We are interested in identifying small molecules from natural plant origin, which targets both AR and AKT signaling for the prevention and treatment of CRPC. Ellagic acid/ellagitannins, abundantly present in the pomegranate and berries, are actively metabolized by the intestinal microflora to Urolithin-A (UA). Oral administration of UA has been equivocally shown to be highly bioavailable in the prostate gland, and is non-toxic. In our in vitro studies, UA treatment inhibited the growth of both AR-expressing (LNCaP, C42B) and AR-negative (PC-3) prostate cancer cell lines. The molecular analyses suggested that UA transcriptionally regulated AR function and its downstream events in these cell lines. In addition, dihydrotestosterone (DHT) induced AR signaling was attenuated by UA. While dissecting the effect of UA on AKT signaling, we found UA inhibited pAKT (Ser 473) expression and its pro-survival target genes. Phenotypic analysis confirmed UA reduces the motility and invasive potential of prostate cancer cells by inhibiting the expression of genes that are implicated in the epithelial-to-mesenchymal transition (EMT) (e.g., β-catenin, vimentin, Snail, and Slug). We also demonstrated the in vivo efficacy of UA against CRPC. Oral administration of UA (50 mg/kg body weight) inhibited prostate tumor growth in xenografts from PC-3 and C4-2B cells. Moreover, histopathological evaluation of the xenografts revealed a marked reduction in the tumor cell density, loss of anisocytosis and anisokaryosis, and lower mitosis in animals that received UA as compared to the control group. Studies are underway to analyze the plasma and tissue levels of UA and our ongoing immunohistochemistry studies may validate the in vitro findings and confirms whether AKT/AR are the target of UA. Together, these results suggest that targeting and thus, overriding both AR and AKT mediated pro-survival signaling could be an effective strategy for preventing the progression of CRPC. Citation Format: Manicka V. Vadhanam, Trinath P. Das, Suman Suman, Lakshmanan Annamalai, Chendil Damodaran. Urolithin A (UA) inhibits both androgen receptor and AKT signaling and prevents the progression of castration resistant prostate cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4651. doi:10.1158/1538-7445.AM2015-4651
Smart Engines: Concept and Application

This article briefly describes the concept of “smart” engine components and discusses various applications of this concept that are currently in the research phase. The interdisciplinary nature of smart engine research is then illustrated through a review of dynamic control of aerodynamic instabilities in gas turbine compression systems rotating stall and surge. It has been demonstrated that these instabilities can be stabilized by active feedback control. Basic interdisciplinary questions have evolved based on this research, including identification of unsteady fluid mechanics, choosing suitable signals and wave launchers for implementing feedback, and enabling technologies for real-world control of engine components.
Potential applications of the interferons in oncology: Lessons drawn from studies of human melanoma

Nineteen patients with hairy cell leukemia (HCL) were treated with recombinant interferon alpha-2a/Roche (Roferon) given by daily intramuscular injection of 3 X 10(6) for 6 months followed by three injections per week. Pretreatment and follow-up marker studies were performed on 14 of 16 evaluable patients. Peripheral blood and bone marrow mononuclear cells were analyzed by flow cytometry for reactivity with monoclonal antibodies to B cell associated surface antigens (B1, B2, B4, BL1, BL3, and BL7) and two hairy cell (HC) antibodies, anti-HCL1 and HCL3. B cell monoclonality was determined by clonal excess calculation of immunoglobulin light chains. Right angle scatter analysis showed that HCs are scattered between lymphocytes and monocytes. Nine of the 14 patients achieved a partial remission, three patients achieved a minimal response, and two patients failed therapy. Phenotypically, ten patients had kappa clonal excess and four had lambda clonal excess. These cases expressed a mature B cell phenotype, ie, BL1-, BL7+, BL3+, B1+, B2-, B4+, HCL1+, HCL3+. All 12 responders became nonreactive with monoclonal antibodies 4 to 8 weeks after therapy; in five of these cases, reactivity with monoclonal antibodies was again detected at the time of maximum clinical response (2 to 8 months), without affecting clinical response status. In four of 12 responders, clonal excess disappeared 4 to 8 weeks after therapy; in three more patients, clonal excess disappeared at the time of maximum clinical response (2 to 4 months); in three patients, clonal excess disappeared from the peripheral blood, but not from the bone marrow at the time of maximum clinical response (3 to 5 months); two patients had persistent clonal excess. In the two failures, there was persistence of clonal excess and reactivity with monoclonal antibodies. This study shows that phenotypic analysis is a sensitive and objective method of assessing response of HCL to alpha interferon. This system could be used as a model for the study of other B cell neoplasms.
Preferential growth of Pt on rutile Ti O 2

The characterization of a $\mathrm{Pt}∕\mathrm{Ti}{\mathrm{O}}_{2}$ (Degussa P25) catalyst system using atomic resolution $Z$-contrast images and electron energy loss spectroscopy has recently revealed that Pt particles have a strong tendency to nucleate on the rutile phase of $\mathrm{Ti}{\mathrm{O}}_{2}$ rather than on anatase. Comparative ab initio pseudopotential calculations for Pt and ${\mathrm{Pt}}_{2}$ on the stoichiometric and reduced $\mathrm{Ti}{\mathrm{O}}_{2}$ surfaces and for oxygen vacancy $({V}_{\mathrm{O}})$ formation energies are performed to address the microscopic origin of this finding. The results, which show that Pt binds more strongly to anatase surfaces, indicate that the selective growth of Pt on rutile must be controlled by the lower formation energy of ${V}_{\mathrm{O}}$ on rutile and possibly by the stronger tendency of larger Pt particles to nucleate at the ${V}_{\mathrm{O}}$ sites of rutile compared to anatase.
Compartmental analysis of potassium efflux from growth-oriented heart cells

Radioisotopic flux studies were initiated with a new preparation of growth-oriented heart cells to determine the contribution of heterogeneous cell types and the limitations of extracellular diffusion in quantitating the passive movement of potassium ions. The efflux of potassium-42 from contractile preparations, which contain two populations of cells, cardiac muscle and fibroblastlike, could be resolved into two components similar to that described for naturally occurring preparations of cardiac muscle. Compartmental analysis of the efflux data, using analog and digital computational methods, resolved the tracer kinetics into a slow compartment (k=0.015 min−1) associated with fibroblastlike cells and a fast compartment (k=0.067 min−1) associated with the cardiac muscle cells. The rate constants derived from compartmental analysis were independent of tracer equilibration and preparation dry weight. Analytical measurements of the preparations provided a quantitative basis for determining the transmembrane potassium fluxes from the tracer kinetics. Cardiac muscle cells stimulated at a rate of 150 min−1 in the presence of 5.4mm external potassium were found to have a potassium efflux of 15.7 pmoles cm−2sec−1 whereas the value obtained for the fibroblastlike cells was 1.88 pmoles cm−2sec−1. Diffusional limitations of42K efflux were analyzed for several important variables which can affect isotopic reflux, namely, transmembrane flux, cell volume-to-surface area and cell packing fraction.
An approach for developing support systems for strategic decision making in business

Abstract Strategic comparative advantage through information processing can be achieved by using information to support a complex, strategic decision process. This paper discusses the general requirements of a Strategic Decision Support System (SDSS) and presents a framework for an SDSS which integrates recent advances in both the design of decision support systems and the understanding of complex human decision-making processes. The proposed SDSS architecture is comprised of a network of subsystem interfaces that support all phases of strategic decision-making activities. This SDSS provides a robust framework adaptable to a variety of organizational problem situations.
The type of urinary diversion after radical cystectomy significantly impacts on the patient's quality of life.

Background: In this study, we used a previously well-validated survey to assess the impact of different forms of urinary diversion on overall quality of life in patients with bladder cancer.
A Simple Laser Induced Breakdown Spectroscopy (LIBS) System for Use at Multiple Levels in the Undergraduate Chemistry Curriculum

A LIBS (laser induced breakdown spectroscopy) spectrometer constructed by the instructor is reported for use in undergraduate analytical chemistry experiments. The modular spectrometer described here is based on commonly available components including a commercial Nd:YAG laser and a compact UV-vis spectrometer. The modular approach provides a flexible arrangement that allows the use of the components in other experimental techniques, such as Raman spectroscopy and measurement of lifetimes of excited states. Integrating LIBS into the undergraduate analytical chemistry curriculum gives students experience with this important, emerging analytical method as well as hands-on experience with this common type of laser. Finally, experiments in which the LIBS spectrometer is used in both upper- and lower-division chemistry courses as well as a use for forensic chemistry are outlined.
Measurement of membrane potential in Bacillus subtilis: a comparison of lipophilic cations, rubidium ion, and a cyanine dye as probes.

Two of the commonly used probes for measuring membrane potential—lipophilic cations and the cyanine dye diS-C3(5)—indicated nominally opposite results when tetraphenylarsonium ion was added as a drug to suspensions of metabolizingBacillus subtilis cells. [3H]-Triphenylmethylphosphonium uptake was enhanced by the addition, indicating hyperpolarization, yet fluorescence of diS-C3(5) was also enhanced, indicating depolarization. Evidence is presented that both effects are artifactual, and can occur without any change in membrane potential, as estimated by86Rb+ uptake in the presence of valinomycin. The fluorescence studies suggest that tetraphenylarsonium ion displaces the cyanine dye from the cell envelope, or other binding site, into the aqueous phase. The uptake characteristics of the radiolabeled lipophilic cations were quite unusual: At low concentrations (e.g., less than 10 μm for triphenylmethylphosphonium) there was potential-dependent uptake of the label to a stable level, but subsequent addition of nonradioactive lipophilic cation caused further uptake of label to a new stable level. Labeled triphenylmethylphosphonium ion taken up to the first stable level could be displaced by 10mm magnesium ion, whereas86Rb+ uptake was unperturbed. Association of the lipophilic cations with the surface of de-energized cells was concentration-dependent, but there was no evidence for cooperative binding. This phenomenon of stimulated uptake inB. subtilis (which was not seen inEscherichia coli cells or vesicles) is consistent with a two-compartment model with access to the second compartment only being possible above a critical cation concentration. We tentatively propose such a model, in which these compartments are the cell surface and the cytoplasm, respectively. Triphenylmethylphosphonium up to 0.5mm exhibited linear binding to de-energized cells; binding of tetraphenylphosphonium and tetraphenylarsonium was nonlinear but was not saturated at the highest concentration tested (1mm). The usual assumption, that association of the cation with cell surfaces is saturated and so can be estimated on de-energized cells, therefore leads to undercorrected estimates of cytoplasmic uptake inB. subtilis, and hence to overestimates of membrane potential. We describe a more realistic procedure, in which the estimate of extent of binding is based on a mean aqueous concentration related both to the external concentration and to the much higher internal concentration that exists in energized cells. Using this procedure we estimate the membrane potential inB. subtilis to be 120 mV, inside-negative. The procedure is of general applicability, and should yield more accurate estimates of membrane potential in any system where there is significant potential-dependent binding.
Solid-state synthesis of highly conducting polyphenylene from crystalline oligomers

Paraphenylene oligomers (biphenyl, p‐terphenyl, p‐quaterphenyl, p‐quinquephenyl, p‐sexiphenyl) form electrically conducting complexes with AsF5. Prolonged exposure to AsF5 causes a polymerization of these p‐phenylene oligomers to give highly conducting charge‐transfer complexes of poly(p‐phenylene). Conductivities as high as 50 S/cm have been measured. Powders, thin films, and single crystals of p‐phenylene oligomers have been reacted with AsF5. The undoped oligomers and the doped, compensated, and annealed products have been investigated by means of x‐ray diffraction, and UV‐visible and IR transmission spectroscopy. The x‐ray diffraction studies give evidence for a change in lattice spacings to those characteristic of the crystalline polymer. The spectroscopic measurements during AsF5 doping reveal shifts in absorption bands in the UV and the IR to those characteristic of poly(p‐phenylene). Paraoligophenylenes have also been reacted with elemental potassium in THF solution with trace amounts of naphthalene. Highly conducting complexes were formed (0.5 S/cm for sexiphenyl) but there is no evidence for further polymerization.
How stereotactic core-needle biopsy affected breast fine-needle aspiration utilization: An 11-year institutional review

To determine the effect of stereotactic core-needle biopsy (SCNB) on the utilization of breast fine-needle aspirate (FNA) biopsy, we retrospectively reviewed 1,568 cases of breast FNAs that were obtained from 1,188 patients between the years 1990 and 2000. There were 378 positive and atypical cases and 497 negative and unsatisfactory cases in the pre-SCNB group (between 1990 and 1996; 7 years); and 225 positive and atypical cases and 468 negative and unsatisfactory cases in the post-SCNB group (between 1997 and 2000; 4 years). The average number of cases per year in the pre- and post-SCNB groups was 125 and 173, respectively. While the average positive/atypical cases per year in both groups remained relatively constant, the average negative/unsatisfactory cases per year were significantly increased in the post-SCNB group (117 in the post-SCNB vs. 71 in the pre-SCNB). The increase in this group was due to a true increase in the negative diagnoses, since unsatisfactory rate decreased in the post-SCNB group (12.6% in the post-SCNB vs. 9.3% in the pre-SCNB). The sensitivity, specificity, positive predictive value, and negative predictive value were 90%, 79%, 92%, and 82% in the pre-SCNB group and 93%, 86%, 91%, and 90% for the post-SCNB group, respectively. In conclusion, the implementation of SCNB did not result in a decrease in the total number of breast FNAs; however, the distribution of cases changed. FNA is increasingly used to complete the triple test in clinically and radiographically negative cases. Diagn. Cytopathol. 2004;31:106–110. © 2004 Wiley-Liss, Inc.
The Axis of Progression of Disease

Starting with genetic or environmental perturbations, disease progression can involve a linear sequence of changes within individual cells. More often, however, a labyrinth of branching consequences emanates from the initial events. How can one repair an entity so fine and so complex that its organization and functions are only partially known? How, given the many redundancies of metabolic pathways, can interventions be effective before the last redundant element has been irreversibly damaged? Since progression ultimately proceeds beyond a point of no return, therapeutic goals must target earlier events. A key goal is therefore to identify early changes of functional importance. Moreover, when several distinct genetic or environmental causes converge on a terminal phenotype, therapeutic strategies that focus on the shared features seem unlikely to be useful – precisely because the shared events lie relatively downstream along the axis of progression. We therefore describe experimental strategies that could lead to identification of early events, both for cancer and for other diseases.
Polyester composite mesh for laparoscopic paraesophageal hernia repair.

Recent evidence supports the use of prosthetic reinforcement material during laparoscopic hiatal hernia repair; however, the search for appropriate prosthetic materials is still under investigation...
A theory of thermal isomerization rates

A theory of the rate of thermal isomerization based on the theory of radiationless transitions is presented. We discuss its relation to the Fermi golden rule and its application to the isomerization of butadiene to cyclobutene.
Are university researchers at risk for patent infringement

Academic researchers have regularly ignored patents on key technologies as a strategy to maneuver around patent thickets and freedom-to-operate issues, but they may be more at risk than they realize.
Frictional sliding modes along an interface between identical elastic plates subject to shear impact loading

Frictional sliding along an interface between two identical isotropic elastic plates under impact shear loading is investigated experimentally and numerically. The plates are held together by a compressive stress and one plate is subject to edge impact near the interface. The experiments exhibit both a crack-like and a pulse-like mode of sliding. Plane stress finite element calculations modeling the experimental configuration are carried out, with the interface characterized by a rate and state dependent frictional law. A variety of sliding modes are obtained in the calculations depending on the impact velocity, the initial compressive stress and the values of interface variables. For low values of the initial compressive stress and impact velocity, sliding occurs in a crack-like mode. For higher values of the initial compressive stress and/or impact velocity, sliding takes place in a pulse-like mode. One pulse-like mode involves well-separated pulses with the pulse amplitude increasing with propagation distance. Another pulse-like mode involves a pulse train of essentially constant amplitude. The propagation speed of the leading pulse (or of the tip of the crack-like sliding region) is near the longitudinal wave speed and never less than √2 times the shear wave speed. Supersonic trailing pulses are seen both experimentally and computationally. The trends in the calculations are compared with those seen in the experiments.
Characterization of electrochemical photovoltaic cells using polycrystalline CdSe and CdTe electrodes grown by a liquid metal-vapor reaction

Polycrystalline CdSe and CdTe layers were fabricated by putting liquid Cd in contact with Se or Te vapors under constant Ar flow. The crystalline structure, surface properties, and semiconducting properties of these materials have been determined. Both materials were found to be {ital n}-type semiconductors. The results show that, under the proper experimental conditions, the liquid metal-vapor reaction enables the synthesis of polycrystalline CdSe photoelectrodes with a 6.9% energy conversion efficiency when used in an electrochemical photovoltaic cell under 80 mW/cm{sup 2} of white light illumination. This efficiency rates amongst the highest ones measured under similar conditions using polycrystalline CdSe. These CdSe layers have a majority charge carrier density of {ital N}{sub {ital D}}=2.6{times}10{sup 17} cm{sup {minus}3} and possess a highly textured surface which is assumed to be mainly responsible for the high photovoltaic efficiency. The highly textured CdTe samples obtained by this process, however, show a photovoltaic conversion efficiency of only 0.2%, and this is seen to be mainly due to their high majority charge carrier density of {ital N}{sub {ital D}}=7.8{times}10{sup 19} cm{sup {minus}3}.
A NEW CLASS OF SUPRAMOLECULAR, MIXED-METAL DNA-BINDING AGENTS : THE INTERACTION OF RUII,PTII AND OSII,PTII BIMETALLIC COMPLEXES WITH DNA

A new type of mixed-metal, supramolecular complex has been designed that incorporates a platinum center to allow binding to DNA. The interaction of two such platinum heterobimetallic complexes of t...
Analysis of the Curvature in Bicomponent Fibers with Complex Cross Sections

The theoretical analysis based on elementary beam theory and the minimization of strain energy, is developed to predict curvatures of bicomponent fibers with arbitrary cross sections. Comparison of the present prediction with other published results is made in the case of rectangular cross section.
Pseudo-B12 joins the cofactor family.

Over 50 years ago, a deadly autoimmune disease known as pernicious anemia, which is characterized by neurological and hematological abnormalities, had no known cure. The isolation of the anti-pernicious anemia factor from liver extracts by Folkers and Smith in 1948 represented a breakthrough in the treatment of this disease (21, 25). Named vitamin B12, this compound could be isolated as pure, red crystals from various animal and microbial sources, and the X-ray crystal structure of this complex molecule, one of the largest nonpolymeric natural compounds, was determined in the 1950s by Dorothy Hodgkin et al. (Fig. ​(Fig.1A)1A) (8). Since that time, thousands of researchers have identified and characterized a variety of enzymes that utilize B12 cofactors, determined the complex pathway for B12 absorption in humans, and elucidated the microbial pathways for B12 biosynthesis. Other forms of vitamin B12 have been found in nature, but their functions are not fully understood. In this issue of the Journal of Bacteriology, Anderson et al. provide evidence that a form of B12 known as “pseudo-B12” (Fig. ​(Fig.1B)1B) is a physiologically important form of B12 in Salmonella enterica serovar Typhimurium (1). FIG. 1. Corrinoids produced by S. enterica. Cobalamin (A) and pseudo-B12 (B) differ in their α-axial ligands. The β-axial ligand (R) is 5′-deoxyadenosine or -CH3 in B12 cofactors and -CN in vitamin B12. Collectively, these molecules are ... Unlike all other vitamins, vitamin B12 is not produced by plants; rather, its biosynthesis is restricted to certain prokaryotes (23). Animals obtain B12 from food or, in some cases, directly from resident B12-producing microbes (28). S. enterica has long been used as a model organism for studying B12 biosynthesis (23).
interstitial doping and oxygen exchange in superconducting La2CuO4+δ

Abstract The oxygen doping of lanthanum cuprate to generate superconductiving La 2 CuO 4+ δ (0 2 (g) bursts is proposed.
NOSOCOMIAL INFECTION MORTALITY ON PEDIATRIC SERVICES IN THE UNITED STATES, 1975-1983

National Nosocomial Infections Study (NNIS) hospitals conduct prospective surveillance for nosocomial infections (NI) using uniform definitions. Between January 1975 and November 1983, 8122 NI were reported in 701,565 patients discharged from pediatric services; the NI rate was 1.2 per 100 discharges. Among infected patients, 474 deaths occurred (fatality rate 5.8%). The fatality rate was highest in patients with intra-abdominal (18.4%) and CNS (14%) infections, 1° bacteremia (13%) and pneumonia (9%). However, many of the deaths were not the direct result of the NI. Infection control personnel determined that 142 (30%) of the 474 deaths were caused by the NI. The proportion of deaths that were caused by the NI was similar at medical school affiliated and non affiliated hospitals (30% vs 25%, p>0.05). The proportion of infections in which the NI caused death was highest for CNS (11%) and intraabdominal (9.5%) infections. NI associated with 2° bacteremia caused death approximately 6 times more often then those without 2° bacteremia (5.5% vs 0.93%, p<0.001). NI with gram-negative bacilli resistant to gentamicin or tobramycin caused death more often then those with susceptible strains (7.9% vs 1.8%, p <0.001). Infection control efforts should be focused on the prevention of those pediatric NI associated with the highest mortality.
Embedding methods for semidefinite programming

This paper is devoted to the study of embedding methods for semidefinite programming problems using the duals formulated by Ramana, Tuncel, and Wolkowicz in 1997. Specifically, if we solve a semidefinite programming problem PD in either standard primal or dual form, a dual problem of PD, which guarantees strong duality i.e. a zero duality gap and dual attainment, is formulated. The semidefinite program PD and its newly formulated dual problem are then embedded in a larger problem. The embedding problem and its Lagrangian dual satisfy the generalized Slater conditions, and therefore, any path-following primal–dual interior-point method can be applied to solve this embedding problem pair. Like embedding methods appearing in the literature, a solution of the embedding problem can be used to extract the information about the original program PD.
A comparison of glutathione-dependent enzymes in liver, gills and posterior kidney of channel catfish (Ictalurus punctatus).

Abstract 1. Six enzymes which collectively catalyze a number of glutathione-dependent synthetic, catabolic and detoxification reactions were examined along with glutathione status in liver, gills, and posterior kidney of channel catfish (Ictalurus punctatus). 2. Hepatic GSH concentrations were higher than those in kidney or gills. Oxidized glutathione (GSSG) concentrations were similar among the three tissues. 3. Specific (per unit protein) gamma-glutamylcysteine synthetase (GCS) activity was greater in the gills than in liver or posterior kidney. However, total organ GCS activity was greatest in the liver. 4. Specific and total hepatic glutathione peroxidase (GSH peroxidase) activities were substantially greater than those of gills or kidney. 5. Similar specific glutathione reductase (GSSG reductase) activities were observed among all three tissues. 6. All three tissues exhibited glutathione S-transferase (GST) activity towards 1-chloro-2,4-dinitrobenzene (CDNB). Specific and total organ GST activities were highest in the liver, followed by the posterior kidney and gills. 7. Gamma-glutamyltranspeptidase (GGT) activity was present in the posterior kidney, but was undetectable in the gills or liver.