cssi/SciSciGPT-SciSciNet huggingface dataset:
Photochemistry of Planetary Atmospheres and Interstellar Molecules

Photodissociation is the primary loss process for the major components of the atmospheres of planets and for interstellar molecules in unobscured regions of the galaxy. In the case of planetary atmospheres, a fundamental problem is the explanation for the apparent stability of, for example, the CO2 atmosphere on Mars. It now appears that the ultimate solution to this problem is more likely to depend on new knowledge concerning the dynamics of atomic and free radical reactions occurring subsequent to photodissociation rather than on additional details concering the primary photochemical process. For the interstellar molecules, a quantitative discussion is given of the role of photochemistry in determining the lifetime of interstellar molecules. The results of the lifetime calculations have important implications concerning the conditions under which interstellar molecules are formed and the conditions required in order to protect them from photodissociation.
Community Engaged Research: Student and Community Perspectives

Engaged scholarship is defined by Stanton (2008) as research that partners university scholarly resources with those in the public and private sectors to enrich knowledge, address and help solve critical social issues and contribute to the public good. To be truly engaged and of high quality, engagement must take place in the development of the purpose, throughout the research process and in the compilation of the research product. It includes research that incorporates only a few elements of community-engagement, for example having the researchers control the research with the community in more of a consultative role, to research in which both are equal partners throughout the process. This paper will report on a community engaged research course. Feedback from the community agencies and the students involved in the course will be examined in terms of the level of engagement and whether the students were able to make a contribution to the organization. KEYWORDS community engaged research, pedagogy, community partnerships
Morphological plasticity in efferent pathways to the urinary bladder of the rat following urethral obstruction

Partial urethral ligation in female Wistar rats produces changes in the neural control of the lower urinary tract including bladder hyperactivity and facilitation of a spinal micturition reflex pathway. To gain insight into the mechanisms underlying these changes, axonal tracing studies were conducted to examine the postganglionic efferent limb of the micturition reflex pathway which originates in the major pelvic ganglion (MPG). Forty microliters of the tracer Fluoro-Gold (4%) were injected into the right side of the bladder in urethral-obstructed (n = 10) and control (n = 4) rats 6 weeks after urethral ligation or sham surgery. As a control Fast blue (40 microliters, 5%) was injected into the colon to label neurons in the MPG innervating the intestine. Obstructed rats exhibited a 6-fold increase (p less than 0.001) in bladder weight (0.848 gm) compared to controls (0.148 gm). A significant increase (p less than 0.001) in the size of labeled bladder postganglionic neurons in the MPG was noted in obstructed rats (576.4 microns 2, n = 4) as compared to controls (299.6 microns 2). However, labeled, colon postganglionic neurons in the MPG in obstructed (312.9 microns 2) rats were not enlarged compared to controls (359.4 microns 2). Neuronal hypertrophy was not associated with a change in the number of labeled MPG neurons in control and obstructed groups.(ABSTRACT TRUNCATED AT 250 WORDS)
Self and Other in Papua New Guinea

Kenneth E. Read. Return to the High Valley: Coming Full Circle. Berkeley: University of California Press, 1986. xxi. 269 pp. $18.95 (cloth).
Endovascular treatment of abdominal aortic occlusive disease: The impact of stents and intravascular ultrasound imaging

Distal abdominal aortic occlusive disease has been conventionally treated with endarterectomy or bypass grafting. However, today's expanding spectrum of intraluminal devices and techniques may well replace classical surgery in this arterial region in all but a few instances. Since January 1990, we have investigated the potential for such endovascular therapies as thrombolysis, balloon dilation and intravascular stenting in 29 symptomatic patients with a variety of distal abdominal aortic pathologies. The prudent application of these intraluminal therapies hinges on accurate intra-arterial assessment. Arteriographic data are notably inadequate for most endovascular procedures; however, intravascular ultrasound imaging (IVUS) is a newer diagnostic tool that works particularly well in the aortoiliac region where angioscopy is more difficult to utilize for assessment. Using IVUS as a complement to arteriography, we were able to assess the need for 43 Palmaz stents in these cases of distal abdominal aortic pathologies; 23 additional iliac stents were deemed necessary. Moreover, IVUS was the only tool available to confirm adequate stent deployment. Given the apparent long-term success of stents in large-bore arteries, abdominal aortic stenting may ensure proximal inflow to distal vessels, saving many patients from an intra-abdominal operation. The specific intraluminal and transmural data offered by IVUS facilitates stent application and documents adequate deployment, two vitally important elements in the percutaneous treatment of abdominal aortic occlusive disease.
Precise equilibrium constants from spectrophotometric data: BrCl in Br2/Cl2 gas mixtures

The equilibrium constant for the reaction, Br2(g) + Cl2(g) ⇄ BrCl(g), is estimated using the classic spectrophotometric method with precise data and a multispectrum fitting approach. Analysis of spectra for 18 Cl2:Br2 mixing ratios yields K° = 9.1 at 22 °C, with a nominal statistical error (1 σ) of 0.04. This error translates into a remarkable precision of 0.4 cm-1 in the dissociation energy of BrCl, easily beating that for the current best spectroscopic estimate (±5 cm-1). However, a sensitivity analysis shows that K° is susceptible to small systematic errors and minor changes in the least-squares fit model, leading to a more conservative estimate of 2% error. The derived K° is consistent with statistical mechanical estimates that employ the current value for the BrCl dissociation energy, but it differs considerably from some recently measured and used values, which range from 6.4 to 10.4. The revised estimate of the BrCl dissociation energy is &#x1d49f;e = 18 248 ± 2 cm-1.
An intercomparison of radiopharmaceutical kidney kinetics in the mouse

Abstract To satisfy partially the need for controlled intercomparative study in the same bio-system, the renal kinetics of ten radiopharmaceuticals were studied in the Yale-Swiss mouse. Time-course tissue distribution studies of the kidney, liver, blood and skin as well as blood and plasma renal clearance values, cumulative urinary excretion, whole body retention, and total body absorbed radiation doses are reported for 131 I-orthoiodohippurate sodium, 169 Yb-DTPA, 99 m Tc-Sn-DTPA, 113 In-DTPA, 99 m Tc-iron-ascorbic acid-DTPA, 67 Ga-iron-DTPA, 99 m Tc-iron-ascorbic acid, 197 Hg-chlormerodrin with and without meralluride predose, 67 Ga-chloride and 111 In-chloride. For kidney imaging, a rating order is reported based on biological distribution. Requirements for varying kidney functions are discussed. No single compound is clearly superior for renal studies, but insight is provided into important factors which must be considered in the selection of a useful agent for clinical renal function and imaging studies.
Use of a puncture needle for recanalization of an occluded right subclavian vein

We report a patient in whom we used a puncture needle to initiate percutaneous recanalization of a chronic occlusion of the junction between the right subclavian vein and the right brachiocephalic vein. Under fluoroscopic guidance, an 18-gauge needle was used to puncture the right subclavian vein. When contrast material injected through the needle confirmed intravascular location, the needle was advanced until it deflected and perforated an occlusion balloon target positioned within the right brachiocephalic vein. This technique may be useful in patients with central venous occlusions that are refractory to traversal using traditional catheter and guidewire techniques.
Misincorporation of nucleotides opposite five-membered exocyclic ring guanine derivatives by escherichia coli polymerases in vitro and in vivo: 1,N2-ethenoguanine, 5,6,7,9-tetrahydro-9-oxoimidazo[1, 2-a]purine, and 5,6,7,9-tetrahydro-7-hydroxy-9-oxoimidazo[1, 2-a]purine.

A variety of exocyclic modified bases have been shown to be formed in DNA from various procarcinogens (e.g., acrolein, malonaldehyde, vinyl chloride, urethan) and are also found in untreated animals and humans, presumably arising as a result of lipid peroxidation. 1, N2-Ethenoguanine (1,N2-epsilon-Gua), a product known to be formed from several 2-carbon electrophiles, was placed in a known site (6256) in bacteriophage M13MB19 and mutations were analyzed in Escherichia coli, with 2.05% G-->A, 0.74% G-->T, and 0.09% G-->C changes found in uvrA- bacteria. 5,6,7, 9-Tetrahydro-7-hydroxy-9-oxoimidazo[1,2-a]purine (HO-ethanoGua), formally the hydrated derivative of 1,N2-epsilon-Gua, is a stable DNA product also derived from vinyl halides. When this base was placed in the same context, the mutation rate was 0.007-0.19% for G-->A, C, or T changes. The saturated etheno ring derivative of 1, N2-epsilon-Gua, 5,6,7,9-tetrahydro-9-oxoimidazo[1,2-a]purine (ethanoGua) produced G-->A and G-->T mutations (0.71% each). All mutants were SOS-dependent and were attenuated by uvrA activity in E. coli. In vitro studies with four polymerases showed strong blocks to addition beyond the adduct site in the order ethanoGua > HO-ethanoGua > 1,N2-epsilon-Gua. Both E. coli polymerases (pol) I exo- and II exo- and bacteriophage pol T7 exo- showed extensive misincorporation opposite ethanoGua in vitro, with pol I exo- incorporating G and T, pol II exo- incorporating A, and pol T7 exo- incorporating A and G. All modified bases reduced the use of the minus strand bearing the modified guanine in E. coli cells. It is of interest that even though the normal base pairing site of guanine is completely blocked, all of the five-membered ring derivatives incorporate the normal base (C) in >80% of the replication events in E. coli. Major differences in blockage and misincorporation are seen due to what might appear to be relatively modest structural differences, and polymerases can differ dramatically in their selectivities.
Effects of Spatial Constraints on Trunk Kinematics during a Dependent Transfer on an Aircraft

A concern related to air travel by people with disabilities is the risk of low-back injuries while transferring the traveler to or from the aircraft seat. Potential contributing factors to this risk are the spatial constraints imposed by the aircraft's interior. This study investigated the effects of such constraints on the trunk angles, angular velocities, and load moment arm during a two-person dependent transfer between a wheelchair and an aircraft seat. Trunk kinematics were recorded as 33 pairs of subjects transferred a dummy to and from an aircraft seat under unconstrained and constrained conditions. The constraints primarily affected the front transferor, increasing peak trunk flexion, lateral bending, twisting, and load moment arm. Effects on the rear transferor were small and appeared to have offsetting effects on injury risk. The results suggest that the row spacing on an aircraft contributes to low-back injury risk during dependent transfers of travelers with disabilities.
Nucleophilic attack on ketene, 6-methylene-2,4-cyclohexadienylideneketene, 6-oxo-2,4-cyclohexadienylideneketene and 4-oxo-2,5-cyclohexadienylideneketene: an ab initio study

Nucleophilic attack of cyanide anion at the carbonyl carbon was studied computationally at the MP2/6-311+G** level for ketene and at the MP2/6-31+G* and MP2/6-31+G*//HF/6-31+G* levels for all four title compounds. Heats of addition were computed for formation of in-plane adducts and perpendicular adducts where the terms 'in-plane' and 'perpendicular' indicate the direction of nucleophilic attack relative to the ketene plane. Heats of activation were also computed for the two modes of attack. For ketene (1) the in-plane adduct is favored by 37.6 kcal mol - 1 and the in-plane transition state by 18.8 kcal mol - 1 . For the 6-methylene compound (2) the in-plane adduct is favored by 20.1 kcal mol - 1 and the in-plane transition state by 7.3 kcal mol - 1 For the 6-oxo compound (3) the in-plane adduct is more stable by 11.2 kcal mol - 1 whereas the in-plane transition state is preferred by 8.8 kcal mol - 1 . For the 4-oxo compound (4) the in-plane adduct is favored by 19.3 kcal mol - 1 but its transition state by only 2.8 kcal mol - 1 '. The in-plane adduct for ketene is the enolate of acetyl cyanide while the perpendicular adduct is a pyramidalized carbanion attached to a cyanocarbonyl group. Calculated NPA charges support this conclusion. The perpendicular adduct is actually the transition state for rotation about the C-C bond of the ketene moiety in the in-plane adduct, and the 37.6 kcal mol - 1 enthalpy difference is closely matched by the calculated activation enthalpy for rotation about the C-C bond of acetaldehyde enolate: ΔH = 33.6 kcal mol - 1 . The smaller differences found for in-plane vs perpendicular adduct formation for the 6-methylene, 6-oxo and 4-oxo compounds are correlated with decreases in bond length alternation within the six-membered rings which occur upon addition of the nucleophile. Less alternation may be associated with an approach to aromaticity, hence an increase in stability. Both modes of attack lead to reduced bond length alternation, but the amount of alternation is lowered more for the perpendicular adducts than for the in-plane adducts. Changes in the C-O bond lengths are also diagnostic. For all four ketenes the ketenyl C=O length in the in-plane adducts is greater than in the perpendicular adducts reflecting more single bond (enolate) character in the former and more double bond (carbonyl) character in the latter. On the other hand the lengths of the 6-oxo and 4-oxo C-O bonds in their in-plane adducts are smaller than in the perpendicular adducts, consistent with increased conjugation with the oxo substituent in the latter. The greater NPA charge on the 6-oxo and 4-oxo oxygens of the perpendicular adducts supports this conclusion. Calculated enthalpies of activation are in the order ketene > 6-methyleneketene > 6-oxoketene, in qualitative agreement with experimentally determined rates of hydration.
Numerical Simulation Support for a Stress-Based Failure Criterion

Determining tearing concerns in numerical simulations of sheet metal components is difficult since the traditional failure criterion is strain-based and exhibits strain path dependence. Recently, a stress-based, as opposed to a strain-based, failure criterion has been proposed and demonstrated both analytically for sheet materials (Arrieux, 1987 and Stoughton, 2001) and experimentally for tube hydroforming (Kuwabara et al., 2003). The next steps in this progression to acceptance of a stress-based forming limit diagram is to demonstrate how this failure criterion can be used to predict failure of sheet metal parts in numerical simulations. In this paper, numerical simulation results for dome height testing specimens are presented and compared to experimental data from Graf and Hosford (1993). Reasonable agreement was obtained comparing the failure predicted from numerical simulations and those found experimentally.Copyright © 2005 by ASME
Unpaid Work at Home

A substantial number of people take work home without a formal payment arrangement. Using the Work Schedules and Work at Home Supplement to the May 2001 Current Population Survey, this paper investigates the determinants of unpaid work at home. Education, lack of overtime rates, being a team leader, efficiency wages, and larger earnings inequality in an occupation are positively related to the prevalence of unpaid work at home. Unpaid work at home appears to be a form of investment made in expectation of a return in the long run.
Collective excitations are q-deformed bosons

Abstract Collective excitations such as excitons and spin waves, in many-body condensed matter systems have long been described as “almost bosons”. I make the Ansatz that collective excitations are exactly described by quantum-deformed canonical commutation rules (QDCCR): previous results are then lowest approximations to these rules. The q-deformed spectrum produces altered conditions for “q-Bose condensation”.
Stepwise BAN estimators for exponential families with multivariate normal applications

Abstract Consistent, asymptotically efficient and asymptotically normal stepwise estimators are given for a subclass of the uniparametric and multiparametric exponential families. The estimators are derived by using the Robbins-Monro stochastic approximation procedure with certain families of random variables arising from the normalized log-likelihood. Considered in detail are three multivariate normal examples where the maximum likelihood estimators are not tractable.
IL-4-induced transcription factor NFIL3/E4BP4 controls IgE class switching

IL-4 signaling promotes IgE class switching through STAT6 activation and the induction of Ig germ-line e (GLe) transcription. Previously, we and others identified a transcription factor, Nfil3, as a gene induced by IL-4 stimulation in B cells. However, the precise roles of nuclear factor, IL-3-regulated (NFIL3) in IL-4 signaling are unknown. Here, we report that NFIL3 is important for IgE class switching. NFIL3-deficient mice show impaired IgE class switching, and this defect is B-cell intrinsic. The induction of GLe transcripts after LPS and IL-4 stimulation is significantly reduced in NFIL3-deficient B cells. Expression of NFIL3 in NFIL3-deficient B cells restores the impairment of IgE production, and overexpression of NFIL3 in the presence of cycloheximide induces GLe transcripts. Moreover, NFIL3 binds to Ie promoter in vivo. Together, these results identify NFIL3 as a key regulator of IL-4-induced GLe transcription in response to IL-4 and subsequent IgE class switching.
Application of microarray technology to identify novel components of the mammalian circadian clock

Circadian rhythms are integral to eukaryotic life, structuring temporal patterns of physiology and behavior. These cycles are not a passive response to the external environment, but are driven by an internal biological clock with an endogenous period approximating 24 hours. This biological clock and its constituent outputs are represented by regular cycles in gene expression that continue in the absence of any environmental stimuli. The suprachiasmatic nuclei of the hypothalamus (SCN) are the site of a central circadian clock in the mammal. The aim of our current study is to identify and characterise genes that are components of the central oscillator or that are elements of the input or output (clock controlled genes) pathways of the mammalian circadian clock. Time-of-day specific cDNA libraries have been constructed from mRNA extracted from the SCN (0.8 mm3 punched tissue sections) and the cerebella of 2-month old male C57BL/6 mice maintained on a 12:12 light:dark cycle. Animals were sacrificed in three different groups: 0.2−0.7 h after lights on (zeitgeber time [ZT] 0.2−0.7, morning), ZT5.5−6 (midday) and ZT11−11.5 (evening, 0.5−1 h before lights off) (ZT0=lights on). These timepoints and light−dark cycle (entrainment) conditions were chosen since (1) known clock genes and clock-regulated genes peak in expression at various time points after the dark/light transitions, and (2) the amplitudes of rhythmicity are greatest under entrainment conditions. By collecting tissue under entrainment conditions we have been able to use light-induced immediate early genes such as c-fos as internal controls to validate the method. For each collection, brain tissue from 90−120 animals was extracted and frozen rapidly (approximately 1.5 min between sacrifice and freezing of each tissue punch), yielding amounts of poly A+ RNA sufficient to construct representative libraries containing even rare transcripts.
CATIE: A Blended Approach to Situated Professional Development

The Capital Area Technology and Inquiry in Education program (CATIE) is a content-focused, inquiry-based professional development program developed by the Center for Initiatives in Pre-College Education (CIPCE)to assist K-6 teachersinthetechnologyintegrationprocess.Toaddressconcernsofsustainability and cost-effectiveness, this situated model combined online and face-to-face professional development approaches to encourage thoughtprovoking experiences that inspire new pedagogies.CATIE united efforts with the Online Learning Forum (OLF) to offer blended mentoring experi ences situated in and around the classroom context with a special focus on mathematics instruction. CATIE, formerly a high-resource model, transi tioned into a multi-dimensional experience in an effort to sustain technologyrich learning communities and provide quality professional development resources for classroom instruction.This article explores the dimensions of CATIE, the transition to a blended model, and the contributions of this situated model to technology integration professional development.
Cloud Optimized Image Format and Compression

Abstract. Cloud based image storage and processing requires revaluation of formats and processing methods. For the true value of the massive volumes of earth observation data to be realized, the image data needs to be accessible from the cloud. Traditional file formats such as TIF and NITF were developed in the hay day of the desktop and assumed fast low latency file access. Other formats such as JPEG2000 provide for streaming protocols for pixel data, but still require a server to have file access. These concepts no longer truly hold in cloud based elastic storage and computation environments. This paper will provide details of a newly evolving image storage format (MRF) and compression that is optimized for cloud environments. Although the cost of storage continues to fall for large data volumes, there is still significant value in compression. For imagery data to be used in analysis and exploit the extended dynamic range of the new sensors, lossless or controlled lossy compression is of high value. Compression decreases the data volumes stored and reduces the data transferred, but the reduced data size must be balanced with the CPU required to decompress. The paper also outlines a new compression algorithm (LERC) for imagery and elevation data that optimizes this balance. Advantages of the compression include its simple to implement algorithm that enables it to be efficiently accessed using JavaScript. Combing this new cloud based image storage format and compression will help resolve some of the challenges of big image data on the internet.
Finding order within disorder: elucidating the structure of proteins associated with neurodegenerative disease

A number of neurodegenerative disorders, such as Alzheimer’s disease and Parkinson’s disease, involve the formation of protein aggregates. The primary constituent of these aggregates belongs to a unique class of heteropolymers known as intrinsically disordered proteins (IDPs). While many proteins fold to a unique conformation that is determined by their amino acid sequence, IDPs do not adopt a single well-defined conformation in solution. Instead, they populate a heterogeneous set of conformers under physiological conditions. Despite this intrinsic propensity for disorder, a number of these proteins can form ordered aggregates both in vitro and in vivo. As the formation of these aggregates may play an important role in disease pathogenesis, a detailed structural characterization of these proteins and their mechanism of aggregation is of critical importance. However, new methods are needed to understand the diversity of structures that make up the unfolded ensemble of these systems. In this review, we disc...
Correlation between bioassay-derived P4501A1 induction activity and chemical analysis of clam (Laternula elliptica) extracts from McMurdo Sound, Antarctica

Variable levels of halogenated aromatic hydrocarbons were measured in clams (Laternula elliptica) collected from McMurdo Sound, Antarctica. Clams collected in and near Winter Quarters Bay contained high levels of organochlorine compounds, particularly polychlorinated biphenyls (PCBs). A strong gradient has been documented in Winter Quarters Bay that been linked to human activities at McMurdo Station. The activity of clam extracts as inducers of P4501A1-dependent ethoxyresorufin O-deethylase (EROD) activity was determined using in vitro bioassays utilizing rat hepatoma H4IIE cells. The extracts which exhibited the highest induction activities were those derived from clams collected in contaminated areas. Additionally, there was an excellent linear correlation between induced EROD activity versus total PCB levels (r2=0.96). The complimentary nature of both the analytical and bioanalytical data confirms the utility of the latter assay and provides a method for estimating the 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) toxic equivalents in extracts from marine biota.
A Practical Network Coding Scheme over GF(2q) for Multi-User Cooperative Communication

Network coding has been proved to provide significant performance improvement for cooperative communication systems. In this paper, we present a Decode-and-Forward Network Coded (DFNC) scheme over GF(2^q) for multi-user cooperative communication system. In particular, we propose an efficient coding coefficients construction method so as to reduce the transmission overhead from m(q+\log_{2} {m}) to m bits compared with conventional random network coding. Moreover, we propose a novel decoding algorithm---Credit-based Updating Algorithm (CUA), which is combined with channel decoding and works on symbol-level, in order to improve the solvability of decoding set of equations in the destination and fully make use of the advantages from network coding while conventional decoding algorithms (e.g., Gaussian Elimination) ignore it. In this manner, the proposed decoding algorithm helps fully exploit the spatial diversity and redundancy residing in network coding. From the simulation results, we show that DFNC outperforms other transmission schemes in terms of SER and achieves higher diversity order. We also demonstrate that the proposed decoding algorithm provides significant performance gain over conventional decoding algorithm.
Dielectronic satellite spectra for hydrogen-like ions

Abstract The wavelengths, radiative transition rates, Auger rates, satellite intensity factors, and fluorescence yields are presented for dielectronic satellites of nine hydrogen-like ions ranging from Ne 9+ to Xe 53+ . Dipole transitions from 2 ln ′ l ′ → 1 sn ″ l ″, where n ′, n ″ = 2, 3, 4, are included. In this work, relativistic multiconfiguration wave functions are used to calculate energy levels as well as the Auger and radiative transition rates.
Dynamic object recognition using hit-or-miss approach

We develop a new morphological hit-miss algorithm for detecting the features of binary images. The standard hit-miss algorithms use block structure patterns for matching features but in many practical situations this may cause problems because the size of the object is usually unknown. In the proposed algorithm we match the corners of the object instead of the block structure pattern -- this approach works nicely because most objects have different structure elements for the corners. The size of the object plays a less significant role in our recognition algorithm than in the standard algorithms. Our method can be easily adapted to recognize the features of different types of objects. We have implemented the proposed algorithm to recognize the muzzles of guns in military vehicles.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
RELATIONSHIPS BETWEEN PURE TAIL ORDERINGS OF LIFETIME DISTRIBUTIONS AND SOME CONCEPTS OF RESIDUAL LIFE

The concepts of pure-tail orderings as defined by sq- and D-orderings are shown to order the family of reliability life distributions which age smoothly in a natural way. This ordering extends to comparisons regarding the limiting behavior of the residual life, mean residual life, sojourn time between perfect repairs in repairable systems, failure rate and, through the preservation of sq- and D-orderings by various reliability operations, to certain coherent systems of components that age smoothly. Possible applications of the results to the industrial practice of cannibalization are also noted.
The α -recoil effects of uranium in the Oklo reactor

Until recently, it was thought that chemical elements were synthesized only in stars. The discovery of the Oklo phenomenon1–6 in 1972 revealed, however, that there was a nuclear ‘fire’ on the Earth 1,700 Myr ago. We have now carried out a series of acid-leaching experiments on a sample of uranium ore from reactor zone no. 10 of the Oklo mines in Gabon, Africa, and observe anomalously high 234U/238U ratios accompanied by modestly increased 235U/238U ratios in uranium fractions. These results, which can be interpreted as being due to the α-recoil effects of 238U and 239Pu, provide a convenient way of calculating the conversion factor (or the fraction of uranium atoms converted to plutonium) of the natural reactors from radiochemical data, obviating the necessity for mass-spectrometric measurements.
Self-assembled monolayers for liquid crystal alignment: simple preparation on glass using alkyltrialkoxysilanes

A simple procedure for the preparation of octadecylsiloxane self-assembled monolayers (SAMs) on float glass substrates is described. The method utilizes commercial octadecyltriethoxysilane, OTE: n-C18H37Si(OCH2CH3)3, as the SAM precursor, with deposition accomplished in toluene solution using n-butylamine as catalyst. This synthetic approach obviates the use of the problematic trichlorosilanes typically required for the preparation of high quality SAMs, and is characterized by a wide ‘process window,’ utilizing off-the-shelf reagents without special handling.
A New Jewel for Indicating Instruments

IT has been almost universal practice to use highly polished sapphire jewel bearings, cut approximately in the form shown by Figure la, in electric indicating instruments. Such a jewel is commonly known as a “Vee.” The other member of the bearing is a cone-shaped piece of hardened steel or other hard metal also accurately cut and highly polished. Figures 2 and 3 show both the common proportions of these parts and the clearances involved. Figure 2 shows an instrument which has the moving shaft vertical, and Figure 3 an instrument with the moving shaft horizontal. Figure 4a shows typical moving systems and jewel settings.
Economic growth and environmental quality are compatible

Man's relationship to the natural environment and nature's influence upon human life are among the oldest topics of speculation. Until modern times the major reason for concern was the prospect of “diminishing returns.” It was thought that population and economic growth would press against natural resource limits, and that economic welfare would fall to subsistence levels.
Annihilation of Positrons in Liquid Helium

The annihilation scheme of positrons in liquid helium at 4.2\ifmmode^\circ\else\textdegree\fi{}K was studied. Three components in the decay were observed with mean lives: ${\ensuremath{\tau}}_{1}l5\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}10}$ sec, ${\ensuremath{\tau}}_{2}=(2.6\ifmmode\pm\else\textpm\fi{}0.2)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}9}$ sec, and ${\ensuremath{\tau}}_{3}=(1.2\ifmmode\pm\else\textpm\fi{}0.2)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}7}$ sec. The abundance of the ${\ensuremath{\tau}}_{3}$ component is (16\ifmmode\pm\else\textpm\fi{}2)% of all positrons which annihilate in the liquid. Three-quantum annihilation occurs in about 15% of all positron annihilations. This leads to the conclusion that the three components are due to parapositronium, free positron annihilation, and orthopositronium.
Development of environmentally-benign wood preservatives based on the combination of organic biocides with antioxidants and metal chelators.

Wood extractives can be envisaged to protect heartwood by at least three different mechanisms, i.e. fungicide, free radical scavengers/antioxidants and as metal chelators. In short-term laboratory decay tests using two different wood species and decay fungi, the combination of different organic fungicides with various antioxidants and/or metal chelators gave enhanced activity as compared to the organic biocide alone, with the best results usually obtained with all three compounds. Outdoor ground-contact stakes treated with a biocide and antioxidant combination and exposed for 30 months also gave enhanced protection against both decay fungi and termites. It was concluded that the combination of an organic biocide with metal chelating and/or antioxidant additives gives enhanced protection to wood against fungi as compared to the biocide alone and, consequently, it may be possible to develop environmentally-benign wood preservative systems based on this idea.
Laboratory Studies of Gasification Kinetics for Western Coals Under Conditions Expected During In-Situ Combustion

Kinetics for the reaction of steam with western subbituminous chars are described for operating conditions characteristic of those expected during underground gasification of these coals. The mineral matter present in these coals has been found to have significant catalytic activity for the water-gas-shift reaction. In addition, the inorganic constituents of brackish waters naturally occurring in aquifers in the West have been found to have little effect on the gasification rates.
No Persistent Changes in Pasture Vegetation or Seed Bank Composition after Fallowing

The practice of fallowing pastures during the growing season is intended to increase plant diversity and allow natural reseeding of forage grasses. Fallowing delivers these benefits in New Zealand, but has been adopted on rotationally stocked farms in the northeastern United States with little or no quantitative assessment. Allowing the pasture to remain ungrazed may allow weedy species to produce seeds, and could reduce legume populations. We measured the seed bank composition (n = 23) and aboveground vegetation (n = 32) in paddocks that had been fallowed from 0-6 yr previously on an organic dairy in Maryland. Transect sampling was used to characterize the canopy cover of the dominant species three times per year for 3 yr. Germinable seed was identified from 5-cm soil cores collected in the spring and autumn in 2 yr. Fallowing did not produce any changes that persisted for more than 2 yr in either the seed bank or the vegetation of this farm. Tall fescue [Lolium arundinaceum (Schreb.) S.J. Darby-shire] and other pasture grasses set seed, increasing in the seed bank during the fallow year, but this did not produce long-term changes in either the seed bank or the vegetation. The proportion of weedy forbs in the seed bank increased, and the legume cover decreased, but only temporarily. Natural reseeding of tall fescue promoted by fallowing did not cause changes in the vegetation, but could lead to increased endophyte infestation in the endophyte-free tall fescue originally planted.
Deformation of aerogels during characterization

Abstract Aerogels have such low moduli that they can exhibit large strains under very small loads, and this leads to errors in measurements of porosity and pore size. The use of porosimetry, thermoporometry and nitrogen sorption on aerogels is examined and it is shown that all of these techniques underestimate the pore volume and pore size of typical aerogels. Even at the highest pressures there may be no intrusion of mercury at all, so porosimetry serves only to measure the bulk modulus of the aerogel network, not its pore size distribution; an analysis of the conditions for intrusion as a function of modulus and pore size of the gel is presented. Direct experimental observation of a silica aerogel indicates that its volume shrinks by ⋍ 50% as liquid nitrogen condenses in its pores. Consequently, it is likely that the quantity of macropores in aerogels has been seriously overestimated in the past.
On the biosynthesis and metabolism of N-acylethanolamine phospholipids in infarcted dog heart.

Abstract Minced tissues from both infarcted and apparently normal areas of canine myocardium 6 h after ligation of the left descending branch of the coronary artery were incubated with [1,2- 14 C]ethanolamine. In each case substantial amounts of radioactivity were incorporated into both phosphatidylethanolamine and N -acylphosphatidylethanolamine. Incubation of homogenates from the same tissues with N -[1- 14 C]palmitoyl phosphatidylethanolamine yielded labeled N -palmitoyl ethanolamine. The data support the concept that N -acylethanolamines, pharmacologically active compounds which accumulate in infarcted myocardium, are produced by N -acylation of ethanolamine phospho-lipids followed by phosphodiesterase action.
ASIXTEENTH-CENTURYDRAWINGOFAN ASTROLABE MADE BY KHAFĪF GHULĀM 'ALĪ B. 'ĪSĀ (c. 850 A.D.)

RIASSUNTO Questo articolo identifica un disegno, eseguito da Antonio da Sangallo il Giovane, di un astrolabio costruito dal famoso astrolabista di Baghdad Khafif (850 d.C. ca.). Al Museum of the History of Science di Oxford e conservato l'unico astrolabio di Khafīf oggi esistente, del quale si pubblica una fotografia. Grazie alla notevole precisione della copia di Antonio e alla somiglianza di questa copia con la rete di un astrolabio anonimo, pure conservato a Oxford, sembra possibile confermare che la parte non firmata debba essere stata costruita dallo stesso Khafif. Il presente articolo conclude che l'astrolabio del disegno deve essere stato un lavoro tardo di Khafif, dato che e piu completo di quello di Oxford, con aggiunte apportate in Andalusia prima che Antonio lo vedesse.
Biochemical, Mössbauer, and EPR studies of the diiron cluster of phenol hydroxylase from Pseudomonas sp. strain CF 600.

Phenol hydroxylase of Pseudomonas sp. strain CF600 comprises three components: DmpP is an FAD- and [2Fe-2S]-containing reductase; DmpM is a cofactorless activator protein; and DmpLNO is the oxygenase. Single turnover experiments established that DmpLNO contains the active site, but requires DmpM for efficient turnover: the steady-state turnover rate reaches a maximum at 1.5 DmpM:1 DmpLNO. Chemical cross-linking experiments showed that DmpM interacts with the large subunit of the DmpLNO oxygenase complex. Mossbauer studies revealed that the active site of the oxygenase can accommodate two types of diiron clusters, each of these cluster types having two equivalent sites. Cluster form I, representing typically around 85% of total Fe, has ΔEQ = 1.73 mm/s and δ = 0.54 mm/s, while cluster II exhibits ΔEQ = 0.79 mm/s and δ = 0.48 mm/s. Studies in strong applied magnetic fields suggest that the two iron sites of cluster I are bridged by an oxo group while sites in cluster II appear to be hydroxo-bridged. Reduct...
Mathematical modeling of a robot collision with its environment

In this article the collision of a robot with its environment is studied. In normal applications of a robot arm, a collision takes place because of the velocity of the end effector relative to the object at the time of contract. The collision has effects on the velocities and internal forces of the robotic system. Firstly, the generalized velocities representing joint rates have abrupt changes at the moment of collison with the environment. The mathematical model is derived to establish the quantitative relationship between this abrupt change and the severity of the collision. The latter is represented by either an external impulsive force or the instantaneous change of the linear velocity of the contact point. Secondly, internal to the system, large impulsive forces and torques of constraint may develop at each joint because of the collision. These impulses cause possible damages to the system. The mathematical model is also derived to establish a quantitative relation between the impulsive forces and torquest of constraint and the collision. These two models are applied to a Stanford Arm designed to pick up an object by its end effector, and the consequences of the collision are analyzed.
Brugia malayi: whole genome amplification for genomic characterization of filarial parasites.

Genetic characterization of field isolates and clinical specimens of filarial nematodes is often limited by a shortage of DNA; therefore, we evaluated a multiple displacement amplification (MDA) based whole genome amplification method. The quality of amplified DNA was examined by conventional PCR, real-time PCR, and DNA hybridization. MDA of 5.0 ng of adult Brugia malayi DNA and one-fifteenth of the DNA isolated from a single microfilaria resulted in 6.3 and 4.2 μg of amplified DNA, respectively. Amplified DNA was equivalent to native genomic DNA for hybridization to B. malayi BAC library clones or to an oligonucleotide microarray with approximately 18,000 filarial DNA sequences. MDA is useful for whole genome amplification of filarial DNA from very small amounts of starting material. This technology will permit detailed studies of genetic diversity that were not previously feasible.
A decision theoretic approach to time series analysis

In this article we present a solution to the problem of constructing a statistical decision theory for discrete stochastic processes. In doing this we also develop a theoretical frame-work for combining cross-section and time-series analyses of non-stationary random processes. Our general approach is similar to that used by Blackwell and Girschick in their book,Theory of Games and Statistical Decisions [4]. More specifically, the statistician is always pictured as a gambler playing a game against nature, and the strategies of nature are identified with the unknown statistical parameters in the relevant problem.
Electrochemical investigations of tetraphenylethylene in dimethylformamide using Fourier transform faradaic admittance measurements (FT-FAM)

Abstract We have investigated the electrochemical reduction of tetraphenylethylene in dimethylformamide-0.10 M tetrabutylammonium tetrafluoroborate electrolyte. The array processor enhanced version of the FT-FAM instrumentation was used in these studies. Extensive measurements, including temperature and concentration dependence, were performed. Analysis of the data led to the conclusion that the observed wave represents a two-electron reduction with a very small potential separation (Δ E ) between the first and second waves so that the waves overlap and only one admittance peak is observed at all frequencies. This electron transfer pair is coupled to a reversible homogeneous redox reaction (“nuance of the EE mechanism”). Other mechanisms, such as the simple EE and ECE without “nuances”, were inconsistent with one or more aspects of the data arrays obtained. The mechanism presented is the only one examined which seems consistent with all aspects of the experimental results. The estimation of thermodynamic and kinetic parameters is discussed, showing that it is possible to obtain reasonably accurate values of all relevant parameters. Three unique theoretical working curves were developed for this study. This investigation is especially illustrative of the power of the array processor enhanced FT-FAM instrumentation.
An Efficient High-Order Time Integration Method for Spectral-Element Discontinuous Galerkin Simulations in Electromagnetics

We investigate efficient algorithms and a practical implementation of an explicit-type high-order timestepping method based on Krylov subspace approximations, for possible application to large-scale engineering problems in electromagnetics. We consider a semi-discrete form of the Maxwell's equations resulting from a high-order spectral-element discontinuous Galerkin discretization in space whose solution can be expressed analytically by a large matrix exponential of dimension $$\kappa \times \kappa $$ ? × ? . We project the matrix exponential into a small Krylov subspace by the Arnoldi process based on the modified Gram---Schmidt algorithm and perform a matrix exponential operation with a much smaller matrix of dimension $$m\times m$$ m × m ( $$m\ll \kappa $$ m ? ? ). For computing the matrix exponential, we obtain eigenvalues of the $$m\times m$$ m × m matrix using available library packages and compute an ordinary exponential function for the eigenvalues. The scheme involves mainly matrix-vector multiplications, and its convergence rate is generally $$O(\Delta t^{m-1})$$ O ( Δ t m - 1 ) in time so that it allows taking a larger timestep size as $$m$$ m increases. We demonstrate CPU time reduction compared with results from the five-stage fourth-order Runge---Kutta method for a certain accuracy. We also demonstrate error behaviors for long-time simulations. Case studies are also presented, showing loss of orthogonality that can be recovered by adding a low-cost reorthogonalization technique.
Direct signaling from astrocytes to neurons in cultures of mammalian brain cells

Although astrocytes have been considered to be supportive, rather than transmissive, in the adult nervous system, recent studies have challenged this assumption by demonstrating that astrocytes possess functional neurotransmitter receptors. Astrocytes are now shown to directly modulate the free cytosolic calcium, and hence transmission characteristics, of neighboring neurons. When a focal electric field potential was applied to single astrocytes in mixed cultures of rat forebrain astrocytes and neurons, a prompt elevation of calcium occurred in the target cell. This in turn triggered a wave of calcium increase, which propagated from astrocyte to astrocyte. Neurons resting on these astrocytes responded with large increases in their concentration of cytosolic calcium. The gap junction blocker octanol attenuated the neuronal response, which suggests that the astrocytic-neuronal signaling is mediated through intercellular connections rather than synaptically. This neuronal response to local astrocytic stimulation may mediate local intercellular communication within the brain.
Ribbon concordance and a partial order on S-equivalence classes

Abstract A partial order is defined on S -equivalence classes which relates well to ribbon concordance of classical knots.