cssi/SciSciGPT-SciSciNet huggingface dataset:
Carcinogenicity of Perfluoroalkyl Compounds

This chapter reviews the information available on the carcinogenic potential of perfluoroalkyl acids in both animals and humans. Historically, perfluorooctanoic acid (PFOA) and perfluorooctanesulfonate (PFOS) have been the most widely used members of this chemical class making these the subject of the largest proportion of the reported studies. Caution needs to be exercised in projecting the biological activities of any of the chemicals in this family based on results from others. For example, considering the three chemicals for which lifetime studies in rats are available, the outcomes were different with no increase in tumors seen with perfluorohexanoic acid (PFHxA), liver adenomas seen with PFOS, and adenomas of the liver, testis, and pancreas seen with PFOA. Mechanistic studies suggest that the liver tumors seen with PFOA reflect the activation of PPARα while the mechanism for tumor formation in the testis and pancreas is less clear. Epidemiologic studies have been reported for several levels of population exposure. Limited evidence of associations with kidney and testicular cancer has been reported in studies among community members exposed to drinking water contaminated by PFOA. Studies in workers exposed to higher levels of both PFOA and PFOS have not shown consistent evidence for an association with any specific cancer type. Studies in populations exposed to low levels of PFOA and PFOS have shown equivocal results for a variety of cancers with no consistent associations. Based on the evidence reported to date, the prospect for developing a carcinogenic outcome following exposure to PFOA and PFOS is remote. For other perfluoroalkyl acids, there is not sufficient evidence regarding their potential carcinogenicity. It should be noted that human exposures to these chemicals is currently quite low and appears to be decreasing.
Polarization and angle dependent transmission through microwave metamaterials in the Ku frequency band

We present experimental and theoretical study of the transmission of linearly polarized microwaves through a slab of negative index of refraction metamaterials. A metamaterial slab was designed with an extended S-Shaped Split Ring Resonator (ES-SRR) to exhibit a negative index of refraction around 13.25 +/- 0.75 GHz which is a commercially leased microwave band for satellite communications. The metamaterial slab exhibits a pass-band filter transmission behavior around 12.5 GHz to 14 GHz, encompassing the Ku-band.
Hope, Rage and Inequality: A Critical Humanist Inclusive Education

In this paper we examine challenges faced by students of color in an intervention program [Opportunity] in a socially stratified community on California’s Central Coast. The purpose of this paper is to name and discuss the problems students face: lack of support from the teaching community, the school staff and the administration of the parent district. We further identify challenges experienced by students and their teachers while highlighting strengths and weaknesses of educational programs and their reciprocal effects on participants. Finally, we seek to share a narrative overview of a teacher’s experience in creating the conditions for an inclusive education.
Tax Competition and the Trend toward Territoriality

Tax competition is with us to stay, and the drive toward territorial taxation of multinationals will continue. Ultimately, it makes sense to tax corporations on a source basis because corporate residence is not very meaningful. But if the correct reforms to CFC rules are undertaken together with enhanced transfer pricing enforcement (e.g., by combining the arm's length standard with formulary solutions, as I have suggested elsewhere), such trends are not necessarily harmful to maintaining a stable corporate tax base.
Scaling of polymer drag reduction with polymer and flow parameters in turbulent channel flow

The scaling of polymer drag reduction with polymer and flow parameters has been investigated using results from direct numerical simulations (DNS) of dilute, homogeneous polymer solutions in turbulent channel flow. Simulations were performed using a mixed Eulerian-Lagrangian scheme with a FENE-P dumbbell model of the polymer. The full range of drag reduction from onset to maximum drag reduction (MDR) is reproduced in DNS with realistic polymer parameters, giving results in good agreement with available experimental data. Onset of drag reduction is found to be a function of both the polymer concentration and the Weissenberg number, in agreement with the predictions of de Gennes[1]. The magnitude of drag reduction increases monotonically with decreasing viscosity ratio, β, for 1.0 > β > 0.98, saturates to a plateau for 0.98 > β > 0.9, and slowly decays for 0.9 > β when the solution ceases to be dilute. The magnitude of drag reduction at saturation is a strong function of the Weissenberg number. A \( We_\tau \sim O\left( {{\mathop{\rm Re}\nolimits} _\tau /3} \right) \) is needed to achieve MDR. The presence of the polymer results in attenuation of the small scales along with enhancement of the large scales in the spectra of the streamwise turbulent velocity fluctuations, and attenuation of all scales in the spectra of cross-stream turbulent velocity fluctuations. The degree of attenuation and the range of affected scales increase with the Weissenberg number and with the polymer concentration up to the saturation concentration. At saturation concentration, the cross-stream size of the largest attenuated eddies in the streamwise spectra conform to the predictions of Lumley's theory[2, 3], while at concentrations below the saturation, they conform to a modified version of de Gennes's theory[1]. The net effect of the polymer can be represented by an effective viscosity with a peak magnitude of \( v_{eff} \sim O\left( {0.1\lambda u_\tau ^2 } \right) \) at saturation, in agreement with the predictions of Lumley's theory[2, 3].
Temporal effect of applied pressures on observed alveolar recruitment

Lung recruitment has been hypothesized to be an important component of protective ventilatory strategy in acute respiratory distress syndrome. Determination of optimal recruitment strategies is limited by uncertainty regarding the relationship between time, pressure, and recruitment at the alveolar level. In this study, we assessed the temporal characteristics of alveolar recruitment.
Reversal of Radiation Resistance in LNCaP Cells by Targeting Apoptosis through Ceramide Synthase

Cell lines derived from human prostate cancer are regarded as relatively resistant to both radiation-induced clonogenic death and apoptosis. Here we attempted to modulate the response of LNCaP prostate cancer cells to radiation therapy (XRT) by pretreatment with 12-O-tetradecanoylphorbol acetate (TPA), a known apoptogenic agent in LNCaP cells. Using plateau-phase cultures, we investigated the response of these cells to XRT, TPA, and a combination of XRT and TPA. LNCaP irradiation did not result in ceramide generation or apoptosis. However, pretreatment with TPA enabled XRT to generate ceramide via activation of the enzyme ceramide synthase and signal apoptosis. Apoptosis was abrogated by the competitive inhibitor of ceramide synthase, fumonisin B1. Furthermore, when transplanted orthotopically into the prostate of nude mice, LNCaP cells produced tumors that recapitulated the responses of LNCaP cells in vitro. XRT or TPA failed to signal apoptosis in LNCaP tumors, whereas a combination of the two resulted in substantial (20-25%) apoptosis within 24 h. There was an additional benefit associated with this regimen because TPA pretreatment protected the adjacent rectum from radiation-induced apoptosis. This represents the first description of signaling-based therapy designed to overcome one form of radiation resistance expressed preferentially in LNCaP human prostate cancer cells.
Ion damage in 316 stainless steel over a broad dose range

Microstructural evolution was examined in annealed 316 stainless steel after heavy-ion bombardment in the range 1 to 256 dpa at 900 K with simultaneously implanted helium at a rate of 10 appm/dpa and deuterium at a rate of 25 appm/dpa. Phase decomposition was rather limited compared with that in neutron irradiations; only an unidentified plate-like precipitate at low dose, and blocky M 2 3 C 6 particles on grain boundaries were formed. Swelling from cavity formation increased with dose to about 20% at about 200 dpa above which it appeared to saturate. Cavity concentrations saturated at about 100 dpa, and dislocations much earlier. The matrix cavities included a persistant complement of ∼7-nm dime small cavities. Similar-size helium bubbles were prolific on the grain boundaries.
Localization and Stability of Introns Spliced from thePem Homeobox Gene

RNA splicing generates two products in equal molar amounts, mature mRNAs and spliced introns. Although the mechanism of RNA splicing and the fate of the spliced mRNA products have been well studied, very little is known about the fate and stability of most spliced introns. Research in this area has been hindered by the widely held view that most vertebrate introns are too unstable to be detectable. Here, we report that we are able to detect all three spliced introns from the coding region of the Pemhomeobox gene. By using a tetracycline (tet)-regulated promoter, we found that the half-lives of these Pem introns ranged from 9 to 29 min, comparable with those of short lived mRNAs such as those encoding c-fos and c-myc. The half-lives of the Pem introns correlated with both their length and 5′ to 3′ orientation in the Pem gene. Subcellular fractionation analysis revealed that spliced Pem introns and pre-mRNA accumulated in the nuclear matrix, high salt-soluble, and DNase-sensitive fractions within the nucleus. Surprisingly, we found that all three of the spliced Pem introns were also in the cytoplasmic fraction, whereas Pem pre-mRNAs, U6 small nuclear RNA, and a spliced intron from another gene were virtually excluded from this fraction. This indicates either that spliced Pem introns are uniquely exported to the cytoplasm for degradation or they reside in a unique soluble nuclear fraction. Our study has implications for understanding the regulation of RNA metabolism, as the stability of introns and the location of their degradation may dictate the following: (i) the stability of nearby mRNAs that compete with spliced introns for rate-limiting nucleases, (ii) the rate at which free nucleotides are available for further rounds of transcription, and (iii) the rate at which splicing factors are recycled.
Surface Area Effects on the Response Mechanism of Ion Optodes: A Preliminary Study

The relationship between the surface-to-volume ratio and the response mechanism of polymeric ion probes (ion optodes) is not well understood. In this work, the surface-to-volume ratio of ion optodes was systematically increased in an attempt to characterize this relationship. Several different batches of ion-selective optodes were fabricated via the solvent displacement method using sodium ionophore X, BME-44, and ETH 1001 for sodium-, potassium-, and calcium-selective optodes, respectively. Dilution of the membrane cocktail with varying amounts of an organic solvent provided a convenient tool to control the resulting particle size distribution. Specifically, ion optodes of five different size distributions were fabricated. An apparent shift of the response function on the pH scale was observed for optodes with identical composition that differed in terms of size. There was a strong correlation between the calculated specific surface area and the apparent ion-exchange constant for all three types of ion optodes. However, there was an indication that selectivity does not substantially correlate with the optode size. We hypothesize that the observed effect is caused by surface phenomena which contribute to the overall optode response. The results reported here may raise a word of caution about the application of established response models, which were developed for macroscopic ion optodes, toward probes at micrometer and submicrometer scales.
Alumina Nanofluid for Spray Cooling Enhancement

Nanofluids have been demonstrated as promising for heat transfer enhancement in forced convection and boiling applications. The addition of carbon, copper, and other high-thermal-conductivity nanoparticles to water, oil, ethylene glycol, and other fluids has been determined to increase the thermal conductivities of these fluids. The increased effective thermal conductivities of these fluids enhance their abilities to dissipate heat in such applications. The use of nanofluids for spray cooling is an extension of the application of nanofluids for enhancement of heat dissipation. In this investigation, experiments were performed to determine the level of heat transfer enhancement with the addition of alumina nanoparticles to the fluid. Using mass percentages of up to 0.5% alumina nanoparticles suspended in water, heat fluxes and surface temperatures were measured and compared. Compressed nitrogen was used to provide constant spray nozzle pressures to produce full-cone sprays in an open loop spray cooling system. Heat fluxes were measured for single-phase and evaporative spray cooling regimes.Copyright © 2007 by ASME
A theoretical framework for building online communities of practice with social networking tools

This paper proposes a theoretical framework as a foundation for building online communities of practice when a suite of social networking applications referred to as collective intelligence tools are utilized to develop a product or solutions to a problem. Drawing on recent developments in Web 2.0 tools, research on communities of practice and relevant theories of learning, and the authors' own action research experience in collaborative knowledge creation utilizing Web 2.0 tools, this paper discusses a learning community's spiraling process as it moves from a given sociocultural context through discourse, action, reflection, and reorganization toward socially mediated metacognition. Un cadre theorique pour construire des communautes de pratique en ligne en utilisant des outils de maillage social Cet article propose un cadre theorique sur lequel edifier des communautes de pratique en ligne lorsqu'on utilise, pour mettre au point un produit ou des solutions a un probleme, une serie d'applications destinees...
Tidal interactions and disruptions of giant planets on highly eccentric orbits

We calculate the evolution of planets undergoing a strong tidal encounter using smoothed particle hydrodynamics (SPH), for a range of periastron separations. We find that outside the Roche limit, the evolution of the planet is well-described by the standard model of linear, non-radial, adiabatic oscillations. If the planet passes within the Roche limit at periastron, however, mass can be stripped from it, but in no case do we find enough energy transferred to the planet to lead to complete disruption. In light of the three new extrasolar planets discovered with periods shorter than two days, we argue that the shortest-period cases observed in the period-mass relation may be explained by a model whereby planets undergo strong tidal encounters with stars, after either being scattered by dynamical interactions into highly eccentric orbits, or tidally captured from nearly parabolic orbits. Although this scenario does provide a natural explanation for the edge found for planets at twice the Roche limit, it does not explain how such planets will survive the inevitable expansion that results from energy injection during tidal circularization.
Solvent Effect in the Synthesis of Sialosyl α(2–6) Galactosides: Is Acetonitrile the only Choice?

In spite of notable achievements for the synthesis of α-sialosides that have been made in the past decades, sialylation reactions often require low temperatures (–40 to –78 °C) and the use of acetonitrile as a solvent. Herein we report that a C-5 oxazolidinone sialosyl donor gives high yields andstereoselectivities in the presence of dichloromethane and/or tetrahydrofuran at 0 °C. Surprisingly, high stereoselectivities and yields are obtained even at ambient temperature in tetrahydrofuran.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Rehabilitating weak complementarity

Using weak complementarity to determine willingness to pay for nonmarket goods is problematic. This note offers a procedure for determining an agent's marginal willingness to pay for a nonmarket good under this assumption that mitigates these problems. JEL Classification: D6; H4; Q2
Accelerated Loading Testing of Stainless Steel Hollow Tube Dowels

The use of dowels in rigid pavements to provide adequate load transfer is a common practice in current pavement design. Since the use of deicing salts in cold climates results in significant deterioration of dowels, the need to optimize performance and reduce pavement life-cycle cost prompts the need for alternatives to common round steel dowel bars. These alternative dowels must be able to withstand corrosion while providing adequate long-term load transfer performance across jointed slabs. Results are presented of the accelerated loading of two jointed test pavement specimens that incorporate one of two types of dowels: a stainless steel hollow tube dowel or an epoxy-coated solid steel dowel. The accelerated loading of these test specimens was accomplished courtesy of the second generation of the Minnesota Accelerated Loading Facility (MinneALF-2), a 10-year-old joint project between the Minnesota Department of Transportation and the University of Minnesota that allows for the realistic simulation of re...
Particle Loss during Adiabatic Capture

In synchrotrons the horizontal betatron acceptance decreases during rf capture and early acceleration because the energy spread increases. We consider this loss of acceptance and propose a method for minimizing it. Consequences of application to the AGS at Brookhaven are presented. It appears that a low energy spread in the injected beam and low rates of acceleration early in the cycle are favorable.
The effect of hyaluronic acid on the sedimentation rate of other substances.

Abstract An investigation of the sedimentation of various substances with molecular diameters of 100–3650 A in hyaluronic acid media has revealed the existence of an exponential relationship between the decrease in the sedimentation rate of a given particle and the square root of the hyaluronic acid concentration. Decreases in sedimentation rates were found to be complex functions of the molecular dimensions of the sedimenting particles but did not appear to depend on the concentration of electrolytes or on the pH. Hyaluronic acid samples which varied about tenfold in molecular weight had similar effects on the sedimentation of albumin. The results that have been noted are in accord with the view that chain polymers form three-dimensional networks which act as macromolecular sieves.
The Apollo Number: Space Suits, Self-Support, and the Walk-Run Transition

BACKGROUND How space suits affect the preferred walk-run transition is an open question with relevance to human biomechanics and planetary extravehicular activity. Walking and running energetics differ; in reduced gravity (<0.5 g), running, unlike on Earth, uses less energy per distance than walking. METHODOLOGY/PRINCIPAL FINDINGS The walk-run transition (denoted *) correlates with the Froude Number (Fr = v(2)/gL, velocity v, gravitational acceleration g, leg length L). Human unsuited Fr* is relatively constant (approximately 0.5) with gravity but increases substantially with decreasing gravity below approximately 0.4 g, rising to 0.9 in 1/6 g; space suits appear to lower Fr*. Because of pressure forces, space suits partially (1 g) or completely (lunar-g) support their own weight. We define the Apollo Number (Ap = Fr/M) as an expected invariant of locomotion under manipulations of M, the ratio of human-supported to total transported mass. We hypothesize that for lunar suited conditions Ap* but not Fr* will be near 0.9, because the Apollo Number captures the effect of space suit self-support. We used the Apollo Lunar Surface Journal and other sources to identify 38 gait events during lunar exploration for which we could determine gait type (walk/lope/run) and calculate Ap. We estimated the binary transition between walk/lope (0) and run (1), yielding Fr* (0.36+/-0.11, mean+/-95% CI) and Ap* (0.68+/-0.20). CONCLUSIONS/SIGNIFICANCE The Apollo Number explains 60% of the difference between suited and unsuited Fr*, appears to capture in large part the effects of space suits on the walk-run transition, and provides several testable predictions for space suit locomotion and, of increasing relevance here on Earth, exoskeleton locomotion. The knowledge of how space suits affect gait transitions can be used to optimize space suits for use on the Moon and Mars.
Learning to Rejuvenate Metropolitan Communities.

Responsive community programming assists urban learners in revitalizing their communities. This chapter examines two community-based organizations that are creating positive changes in local neighborhoods with collaborated strategies for the delivery of educational programming.
Romanowsky staining in cytopathology: history, advantages and limitations

If the entire discipline of diagnostic cytopathology could be distilled into a single theme, it would be the Papanicolaou stain. Yet it was the Romanowsky stain upon which the discipline of cytopathology was founded. Both stains are used today in the cytopathology laboratory, each for a different and complementary purpose. We trace the history of cytopathological stains and discuss the advantages and limitations of Romanowsky-type stains for cytological evaluation. We also provide suggestions for the advantageous use of Romanowsky-type stains in cytopathology.
My Conversion to the Arons‐Advocated Method of science Education

My present concern with undergraduate science education began in the early fall of 1980 when, being assigned by happenstance to teach a physics class for perspective elementary teachers, I gave the first examination. The results showed quite clearly that my brilliant lectures and exciting demonstrations on Newtonian mechanics had passed through the students’ minds leaving no measurable trace. To make matters worse, in a student evaluation given shortly after the exam, some students rated me as among the worst instructors they had ever experienced at our university. Knowing something of the teaching effectiveness of my colleagues, I was severely shaken.
Reinforcing the Need for More Sophistication in Leadership Studies in the Government Sector

We certainly welcome the interest in our recent piece in Public Administration Re view, "Examining the Nature and Signifi cance of Leadership in Government Organizations." This research incorporated the highlights of Dr. Trottier's dissertation, to which Drs. Van Wart and Wang pro vided academic and methodological guidance. It built on the work of Professor Van Wart in calling for more empirical studies, especially testing extant frameworks in various public sector contexts (Van Wart 2003), and his work calling for more testing and refinement of comprehensive models of leadership. The study was empirical (based on 100,657 usable surveys from the 2002 Federal Human Capital Survey), limited to the federal setting, and primarily tested Bass's full range theory, especially teasing out the differences between how followers perceived their leaders' transactional and transformational competence descriptively, as well as what they wanted in their leaders (examined through regression analysis). It found that although federal managers perceive their leaders to possess stronger transactional skills, it was their transforma tional skills that they would like to see emphasized. It also found that Bass's rather elegant, universalistic model held up well, generally consistent with other research, in the government setting. Finally, it found that leadership variables (using Bass's concepts) are considered among the most important in determining follower satisfaction, with the sole exception of per sonal fulfillment of the job, and, when combined, accounted for an adjusted R2 of .736.
Nitric oxide modulates branching morphogenesis in fetal rat lung explants.

Cells of the developing lung express the constitutive nitric oxide synthases (NOSs) I and III. The developmental importance of these enzymes is largely unknown, although a role for nitric oxide (NO...
Bamboo: translating MPI applications to a latency-tolerant, data-driven form

We present Bamboo, a custom source-to-source translator that transforms MPI C source into a data-driven form that automatically overlaps communication with available computation. Running on up to 98304 processors of NERSC's Hopper system, we observe that Bamboo's overlap capability speeds up MPI implementations of a 3D Jacobi iterative solver and Cannon's matrix multiplication. Bamboo's generated code meets or exceeds the performance of hand optimized MPI, which includes split-phase coding, the method classically employed to hide communication. We achieved our results with only modest amounts of programmer annotation and no intrusive reprogramming of the original application source.
How have long-term survivors coped with living with HIV?

With advances in HIV treatment, more individuals have grown older with the disease. Little is known about factors that have helped these survivors manage everyday life with HIV. In this exploratory, qualitative study, we asked, “What has helped survivors cope with challenges of living long term with HIV?” Participants were recruited from a convenience sample of persons living with HIV who obtained treatment at a specialty HIV clinic; 16 long-term survivors of HIV were interviewed. Mean age was 50.13 (SD = 8.30) years; mean time from diagnosis was 16.75 (SD = 5.98) years. Results were broadly dichotomized as coping mechanisms and social supports. Three themes characterized coping mechanisms: disease coping, practical coping, and emotional coping. Social supports included themes of family, friends, professionals, peer groups, and pets. In particular, the power of patient–professional relationships and meanings derived from religion/spirituality were considered by a majority of participants to be influential factors.
A novel quantization noise-cancellation scheme in wideband D/A converters

This paper presents a quantization noise cancellation technique for wideband digital-to-analog converters. Several architectures conforming to the proposed idea are shown, supported with simulation results. Practical system and circuit level issues pertinent to the realization of the technique are also identified.
Magnesium potentiation of iron-transferrin binding.

Abstract The binding of iron to transferrin was studied by loading iron (III) onto apotransferrin in a chloride and a nitrilotriacetate form. When magnesium was added, a marked increase occured in both the rate of iron binding and the maximum level of iron loaded on transferrin utilizing either iron salt. In the absence of magnesium the amount of iron required to achieve 50 percent saturation of the binding sites was 1.6 × 10−4M, whereas when magnesium was added, only about one-third as much iron (0.54 × 10−4M) was required. These data suggest an allosteric effect on transferrin by magnesium which potentiates iron (III) binding.
Generalizing higher-order Bessel-Gauss beams: analytical description and demonstration

We report on a novel class of higher-order Bessel-Gauss beams in which the well-known Bessel-Gauss beam is the fundamental mode and the azimuthally symmetric Laguerre-Gaussian beams are special cases. We find these higher-order Bessel-Gauss beams by superimposing decentered Hermite-Gaussian beams. We show analytically and experimentally that these higher-order Bessel-Gauss beams resemble higher-order eigenmodes of optical resonators consisting of aspheric mirrors. This work is relevant for the many applications of Bessel-Gauss beams in particular the more recently proposed high-intensity Bessel-Gauss enhancement cavities for strong-field physics applications.
Effect of nitrogen content and temperature on the f/sub 3 dB/ of 1.3 /spl mu/m dilute-nitride SQW lasers

Above-threshold frequency response measurements carried out on strain-compensated InGaAs-and-InGaAsN lasers of identical geometry reveal a reduction in the laser relaxation frequency and damping due to the incorporation of nitrogen. Raising of temperature further decreases f/sub 3 dB/.
"Subclinical Cushing's syndrome" is not subclinical: improvement after adrenalectomy in 9 patients.

Background A subgroup of patients with adrenal cortisol hypersecretion fails to meet the biochemical criteria for Cushing’s syndrome. Appropriate therapy for this entity, subclinical Cushing’s syndrome (subclinical CS), is unclear. We examined outcomes for patients who underwent unilateral adrenalectomy for subclinical CS. Methods Between 2003 and 2006, all patients who underwent adrenalectomy for cortisol hypersecretion caused by an adrenal mass were examined. We analyzed biochemical, metabolic, and clinical outcomes. Results Overall, 24 patients underwent adrenalectomy for adrenal cortisol hypersecretion, of which 9 were found to have subclinical CS. Median serum cortisol was 2.0 μg/dL (range, 1.1–6.1) after 1-mg overnight dexamethasone suppression testing. Suspicious clinical findings on preoperative examination included skin bruising, unexplained weight gain, proximal muscle weakness, abnormal fat pads, skin thinning, fatigue, and facial plethora. During a median follow-up period of 5 months (range, 1–30 months), all 8 patients with easy bruising noted resolution postoperatively. Fatigue improved in 4 of 5 patients, muscle weakness in 6 of 8 patients, and weight in 7 of 9 patients, with a median body mass index change of –2.0 kg/m 2 (range, –7.1 to +0.5 kg/m 2 ). Conclusion Adrenalectomy improves clinical and metabolic parameters for many patients with subclinical CS.
Adaptive increase of O6-methlguanine-acceptor protein in HeLa cells following N-methyl-N′-nitro-N-nitrosoguanidine treatment

We have assayed in extracts of HeLa cells the amount of acceptor protein that removes O6-methylguanine adducts from alkylated DNA. Cells were treated with single or multiple nontoxic doses of N-methyl-N'-nitrosoguanidine (MNNG) and the extracts were analyzed up to 32 h after the last exposure. The acceptor activity assayed immediately (1 h) after single exposures decreases linearly with dose indicating that the acceptor protein is used up by endogenous O6-methylguanine adducts in a stoichiometric reaction. Multiple exposures, assayed 8-24 h after the last exposure, increase the amount of acceptor protein in a dose dependent fashion followed by a decrease above a cumulative dose of 100 ng/ml. Under conditions of maximum induction, there are about 300,000 acceptor protein sites per cell, approximately 3 fold above the constitutive level. Both in adapted and unadapted cells the methyl group from O6-methylguanine adducts in the alkylated DNA is transferred to cysteine residues of the acceptor protein(s).
Americium Separations from High-Salt Solutions Using Anion Exchange

The aging of the US nuclear stockpile presents a number of challenges, including the increasing radioactivity of plutonium residues due to the ingrowth of 241Am from the β-decay of 241Pu. We investigated parameters that affect the sorption of Am onto anion-exchange resins from concentrated effluents derived from nitric acid processing of plutonium residues. These postevaporator wastes are nearly saturated solutions of acidic nitrate salts, and americium removal is complicated by physical factors, such as solution viscosity and particulates, as well as by the presence of large quantities of competing metals and acid. Single- and double-contact batch distribution coefficients for americium and neodymium from simple and complex surrogate solutions are presented. Varied parameters include the nitrate salt concentration and composition and the nitric acid concentration. We find that under these extremely concentrated conditions, Am(III) removal efficiencies can surpass 50% per contact. Distribution coefficient...
Toxicological evaluation of the effects of waste-to-energy ash-concrete on two marine species

The toxicological effects of waste-to-energy ash-concrete on survivorship, growth, and fecundity (end-point parameters) of Mysidopsis bahia and on survivorship and growth of Menidia beryllina were evaluated with the 7-d static-renewal toxicity test. Leachate and elutriate solutions were prepared from experimental ash-concrete test cylinders constructed from concrete with additions of either bottom ash (mix BA), mixed bottom ash and scrubber residue, or mixed bottom ash and fly ash (60:40%, mix BA:FA). Control experiments with concrete (without ash) and pH (7-9.5) were conducted to assess any toxic effects of the stabilization process. pH did not affect end-point parameters of Mysidopsis bahia or Menidia beryllina. However, the 100% elutriate solution made from concrete reduced survivorship of Mysidopsis bahia. For experiments with ash-concrete test cylinders with the BA mixture, 10-d leachate solution reduced survivorship of Mysidopsis bahia and the 100% elutriate solutions reduced survivorship of Mysidopsis bahia and Manidia beryllina. With the BA:SR mixture, the 100 and 50% elutriate solutions reduced survivorship of Menidia beryllina. The BA:FA 10- and 5-d leachate solutions and the 100, 50, and 25% elutriate solutions reduced survivorship of Menidia beryllina. The BA:FA 10- and 5-d leachate solutions and the 100, 50, 25% elutriate solutions reduced survivorship of Mysidopsis bahia.
[N-methylnorleucine-(28,31)]cholecystokinin-(26-33) (SNF 8702) activity at a cloned rat CCKB receptor

Abstract [N-methyl-Nle 28,31)]cholecystokinin-(26–33) (SNF 8702) is a highly ligand for the CCKB type of receptor present in the vertebrate central nervous system. Radioligand binding data showing that SNF 8702 binding affinity is reduced by the GTP analog guanylyl-imidodiphosphate suggest that SNF 8702 is an agonist but the ability of SNF 8702 to activate CCKB receptors has not been demonstrated. The present study shows that SNF 8702 is a highly potent agonist at rat CCKB receptors expressed on COS-7 cells and that these receptors are coupled to the mobilization of intracellular calcium. The A50 measured for SNF 8702-induced calcium mobilization (66 pM) is over 6-fold less than that of cholecytstokinin octapeptide (420 pM). Data are also presented showing that SNF 8702 has high binding affinity for these receptors with a Kd value (760 pM) consistent with previous measurements using guinea pig brain tissue preparations.
Air pollution an overlooked factor in climate-related crop damage

While most studies on future crop reduction focus solely on the effects of climate warming, a new study, published in Nature Climate Change, combines climate warming with another factor: ozone pollution. Researchers found that 46% of damage to soybean crops that had been attributed to heat was actually caused by ozone pollution and that other crops—rice, wheat, and corn—are also vulnerable to varying extents.
Wetland development trends in coastal North Carolina, USA, from 1970 to 1984

Coastal wetlands are a valuable resource to North Carolina, USA, representing important habitat for marine organisms and providing flood control areas and buffer zones from marine storms. An analysis of wetland development trends in coastal North Carolina from 1970 to 1984 was conducted using over 3000 files containing 15 years of permitting records. The total amount of coastal wetland area altered due to authorized development under the Coastal Area Management Act (CAMA), the Dredge and Fill Law, and Section 404 of the Federal Water Pollution Control Act is 1740 ha. This represents nearly 2% of the salt marsh wetlands along the coast of North Carolina. The number of permits issued steadily increased during the 1980s; however, the total amount of wetland loss decreased each year. A few large projects in the early 1970s accounted for nearly 70% of all wetland area developed during the 15-year period. Nearly two-thirds of all projects involving wetland destruction involved impacts on high marsh ecosystems. Bulkheads, canals, and filling activities made up 80% of the projects requiring permits; 62% of the permits were issued to private landowners, but this group accounted for only 16% of the losses of wetland area. Utility companies, which accounted for less than 1% of the permits issued, were responsible for 46% of the permitted wetland loss during the 15-year study period. Future studies should address agriculture and forestry practices which are exempt under CAMA laws and therefore their effects on wetland alteration have not been quantified.
H2 saturation on palladium clusters.

The interaction of PdN clusters (N = 2, 3, 4, 7, and 13) with multiple H2 adsorbate molecules is investigated using density functional theory with the hybrid PBE0 functional. The optimal structure for each PdNH2(L) complex is determined systematically via a sequential addition of H2 units. The adsorption energy for each successive H2 addition is computed to determine the maximum number of molecules that can be stably added to a PdN at T = 0 K. The Gibbs free energy is then used to determine the saturation coverage at finite temperature. For N = 2, 3, and 4, a single H2 is found to dissociate, and up to two additional molecular H2 units per Pd atom can bind stably to the clusters at 0 K. At 300 K, one H2 unit dissociates, and only one additional H2 molecular unit per Pd atom is stably bound. For N = 7 and T = 0 K, two H2 units dissociate, and 11 additional H2 units bind molecularly. At 300 K, two units dissociate, and eight are bound molecularly. For N = 3, 4, and 7, we find that an additional H2 unit may ...
Software QA standards-the coming revolution

Current government documents addressing software quality asssurance reflect the confusion in the field and the constraints imposed by the stigma of hardward QA. This paper illustrates these problems by examining, on a comparative basis, elements of the most important Department or Defense (DoD) software QA standards and specifications. The current status, strength, and weakness of these documents are discussd in detail. A new approach being followed by DoD to resolve the issues is briefly described.
Finding a path subject to many additive QoS constraints

A fundamental problem in quality-of-service (QoS) routing is to find a path between a source-destination node pair that satisfies two or more end-to-end QoS constraints. We model this problem using a graph with n vertices and m edges with K additive QoS parameters associated with each edge, for any constant K ≥ 2. This problem is known to be NP-hard. Fully polynomial time approximation schemes (FPTAS) for the case of K = 2 have been reported in the literature. We concentrate on the general case and make the following contributions. 1) We present a very simple O(Km + nlogn) time K -approximation algorithm that can be used in hop-by-hop routing protocols. 2) We present an FPTAS for one optimization version of the QoS routing problem with a time complexity of O(m(n/e)K-1).3) We present an FPTAS for another optimization version of the QoS routing problem with a time complexity of O(n log n + m(H/e)K-1) when there exists an H-hop path satisfying all QoS constraints. When K is reduced to 2, our results compare favorably with existing algorithms. The results of this paper hold for both directed and undirected graphs. For ease of presentation, undirected graph is used.
Defining parametric dependencies for the correct interpretation of speckle dynamics in photon Doppler velocimetry.

Laser speckle dynamics manifest themselves in photon Doppler velocimetry (PDV) data as low-frequency amplitude fluctuations, and analysis of these fluctuations provides insight into the transverse speed of the surface under observation. We previously demonstrated that a single measurement probe is capable of simultaneously measuring (1) axial motion, through frequency analysis of Doppler shifts, and (2) transverse speed, through analysis of the speckle’s coherence time. However, the performance of this technique hinges on a correct understanding of the speckle pattern’s response to surface motion. In this paper, we model the origination of the speckle pattern, and we describe a methodology for calculating the speckle’s coherence time from the autocorrelation of a noisy signal. We then test a suite of optical probes over a range of standoff distances, demonstrating a significant reduction in the speckle’s coherence time, which correlates to the increase in speckle boiling when the target surface is located near a probe’s focal length. We show that spatial regions of decreased coherence time may be predicted a priori by a probe’s parameters, since they stem from boiling dominance. We analyze this result as a function of probe parameters for a surface-scattering target and a volume-scattering target. Although the coherence time’s behavior in the focal plane makes velocity extraction difficult, far from the probe’s focal lengths, we are able to measure rigid body transverse speeds exceeding 20 m/s with an absolute accuracy of ±15% using the speckle dynamics measured by a PDV setup.
Government overload revisited: The case of the federal budget deficit

The thesis of government overload was based on a paradox of governance. While post-1945 economic growth in western democracies appeared to indicate political and economic health, bloated public sectors threatened the loss of political authority. The federal deficit in the United States is interpreted in light of this thesis. Responses to the deficit indicate more “top down” budgeting as a way to avoid, what had been termed by others, "political bankruptcy".
Hybrid Endovascular Pseudoaneurysm and Pulmonary Stenosis Repair in Bovine Arch

This case report details the endovascular management of a large aortic pseudoaneurysm in a high-risk patient with a complicated history using a multi-disciplinary, hybrid approach. The pseudoaneurysm compressed the main pulmonary artery to 5 mm with near complete obstruction of the left main pulmonary artery, while also compromising the lumens of the left superior pulmonary vein and left main bronchus. Furthermore, the patient's left upper extremity arteriovenous dialysis fistula and bovine arch anatomy required a hybrid approach of repair that preserved the fistula while treating the aortic, pulmonary, and bronchial pathology.
A symbolic debugger for real-time embedded Ada software

Rockwell's Ada symbolic debugging system (ASDS) is designed especially for use in debugging and testing embedded system software. ASDS uses a combination of software and special hardware to support unobtrusive monitoring, breakpoint and display facilities that can be applied during the development of an embedded system and during the ‘downstream’ stages of the embedded system life cycle associated with production and field unit testing. The ASDS software kernel executes on a stand-alone monitor processor with modest computational power (e.g. a personal computer), connected to the embedded target system via a target interface that allows the monitor to observe transactions on the target bus in real-time. The use of a monitor processor with modest power limits the degree of ‘high level’ monitoring support—though ASDS can detect the execution of a particular line of source code or access to a particular variable it contains no facilities for monitoring interactions between high-level dynamic objects such as tasks. However, the modest power required for the monitor also reduces its costs, with the result that ASDS debugging and test stations have been readily available to engineers working on system development, in production and in the field. Our description of the ASDS design and implementation focuses on its practical solutions to the problems associated with building and maintaining a symbolic debugging system to support embedded system development.
Quasidifferentials and maximal normal operators

Quasidifferentials are studied with the theory of maximal normal operators. The quasidifferential of a normally quasidifferentiable function is a pair of upper and lower semicontinuous operators, which are special maximal normal operators. The function sum of the upper and lower semicontinuous operators is the Clarke subdifferential of this function. Basic calculus and minimal forms of quasidifferentials are also discussed.
Surface and bulk impurity eigenvalues in the shallow donor impurity theory

Abstract The d ±1 levels are numerically located for the shallow donor impurity when the impurity is at the semiconductor surface for both silicon and germanium. d 0 , d ±2 , and for high n the s, p 0 , and p ±1 levels are found for the case of the impurity somewhere in the bulk material. Generalized energy equations, trial wave functions, effective Bohr radii, and some relative electric-dipole transition probabilities are given.
Volume constriction in a lipid-water liquid crystal using high-pressure x-ray diffraction

We report a measurement of the change in the total volume of a biological lipid-water system when water molecules are removed from the fully hydrated lyotropic liquid-crystal phase, where the water molecules are near a polar interface, to the surrounding bulk water. The commonly used assumption of linear additions of constituent volumes predicts that the water mole fractions of these lipid-water phases should be independent of hydrostatic pressure. The discrepancy between this prediction and our high-pressure x-ray-diffraction measurements is due to a decrease of 0.1 A${\mathrm{\r{}}}^{3}$ in the total volume of the system per molecule of water incorporated into the fully hydrated lipid-water aggregate from the bulk water.
Host-associated differences in fitness within and between populations of a seed beetle (Bruchidae): effects of plant variability.

Experiments were conducted with the sexually reproducing seed beetle Stator limbatus and its hosts in north-central Arizona to determine if it was substructured into units, each specialized for higher fitness on a specific host species. Unlike many studies, we incorporated scale, i.e., conducting experiments between and within beetle populations on seeds from within and between plant species. Of particular interest was whether intraspecific plant variability prevented beetle specialization within beetle populations. Results suggest that S. limbatus is specialized to certain hosts. On the palo verde Cercidium floridum, beetles originally reared from this host had significantly higher emergence compared to beetles transferred from other hosts. We did not test directly for a genetic basis for this. Alternative hypotheses of variation in symbiotic microorganisms in larval guts and maternal effects were assessed. Essentially no bacteria, yeast or protozoa were found, and maternal effects as expressed by varying egg weights were not detected; however, other microorganisms might have been present and maternal effects through inducible enzymes was possible. Caution, then, is needed in any genetic interpretations of our results. The differences on C. floridum were detected from tests between and within beetle populations. Evidence for specialization was not detected on the other hosts, Cercidium microphyllum and Acacia greggii. On the other hosts, beetles performed well regardless of their source. Significant differences were detected among individual plants of C. floridum as to the suitability of their seeds for deveoopment of S. limbatus. No such differences were detected among the other host plants. These patterns of conspecific plant variability are opposite of what is expected if plant variability prevents specialization of beetles to particular species of hosts. Thus, the data suggest seed variability among plants does not prevent specialization to host species in this system. We discuss how the patterns of host use in this study relate to the hypothesis of sympatric host race formation.