bluuebunny/crossref_metadata_2025 huggingface dataset:
Paper as reference material in “Sturm test” applied to insoluble substances
Authors: Musmeci L. , Gucci P. M. B. , Volterra L.
Published: October 2006

The ever‐increasing use of plastics for the packaging, wrapping, and transportation of goods is causing serious concern in regard to their environmental fate when they are carelessly discarded (visual pollution), or disposed off by dumping or by incineration.

For this reason in the last few years in Italy legislation was introduced, specif ing that the plastics used in the manufacturing of shopping bags must be “biodegradable.” The selected test for assaying biodegradability was the modified Sturm method. In applying this assay the choice of reference standard materials, which associates two characteristics—biodegradability and insolubility—is a major problem.

The possibility was investigated of utilizing a paper sample.

The modified Sturm method revealed that the biodegradability of six paper samples varied from 54.5 to 75.2%; papers of two shopping bags showed a biodegradadability of 48.0 and 95.0%, respectively. The variability in the results was due to the composition of the paper.

Results from this study indicate that the kind of paper to be used as reference material in the modified Sturm method has to be strictly selected in order to guarantee the reproducibility of the measures. © 1994 by John Wiley & Sons, Inc..
Studies on Bacillus thuringiensis H‐14 strains isolated in Egypt. VII. Toxicity to insecticide resistant and susceptible strains of mosquitoes
Authors: Abdel‐Hameed A. , Leake C. , Carlberg G. , Niemelä S. I. , El‐Tayeb O. M.
Published: October 2006

Two strains of Bacillus thuringiensis H‐14 (M1 and S128) isolated in Egypt were bioassayed in the laboratory against various insecticide‐susceptible and ‐resistant mosquito species and strains. The results for both bacterial strains tested against Aedes (4 strains), Culex (4 strains), and Anopheles (7 strains) larvae indicate a wide spectrum of larvicidal activity within the Culicidae. Generally, fourth instar larvae of the Aedes and Culex strains were found to be more susceptible than third instar larvae of Anopheles strains. In addition, mosquito strains within the same species that have different geographical origins and/or resistance patterns to residual insecticides were found to have different susceptibilites to the tested preparations. No apparent relationship was found between resistance to insecticides in these mosquito strains and their susceptibility to the tested preparations of B. thuringiensis H‐14. These data indicate that B. thuringiensis H‐14 could be of potential use against insecticide‐resistant vector populations in integrated disease‐control programs. © 1994 by John Wiley & Sons, Inc..
Toxicity of the blue‐green alga (cyanobacterium) Microcystis aeruginosa in drinking water to growing pigs, as an animal model for human injury and risk assessment
Authors: Falconer Ian R. , Burch Michael D. , Steffensen Dennis A. , Choice Mandy , Coverdale O. Robert
Published: October 2006

Hepatotoxins from blue‐green algae are increasingly recognized as a potential hazard in drinking water supplies. The clinical consequences of ingestion include acute or chronic liver injury, with the possibility of enhanced susceptibility to, and growth of, liver tumors. To establish guidelines for water safety requires the demonstration of dose‐dependent effects of toxicity and experimental determination of maximum “no‐adverse‐effect levels.” This paper describes the use of growing pigs as a model for human injury resulting from Microcystis toxins in drinking water. Risk assessment calculations using a series of safety factors are carried out, resulting in a guideline level after incorporating an additional safety factor for tumor promotion of approximately 1.0 μg toxins/L. With the Microcystis used for this trial, that concentration corresponds to 5000 cells/mL. © 1994 by John Wiley & Sons, Inc..
Derivation of water quality objectives for hazardous substances to protect aquatic ecosystems: Single‐species test approach
Authors: Schudoma Dieter
Published: October 2006

Two methodological approaches used to derive quality objectives to protect aquatic communities based on single‐species tests will be described. Water quality objectives to protect aquatic life may be derived on the basis of ecotoxicological tests considering toxicity to bacteria, algae, (small) crustaceans, and fish. This spectrum of species comprises representatives of four trophic levels of water biocoenosis. The lowest no observed effect concentration value of the most sensitive specie is reduced by a safety factor (more appropriate: uncertainty factor) to extrapolate a “safe level” for the aquatic ecosystem. An alternative approach is the use of statistical extrapolation methods based on species sensitivity distributions to calculate maxium permissible concentrations. The approach using uncertainty factors will be compared with the approach using species sensitivity distribution to extrapolate safe levels. ©1994 by John Wiley&Sons, Inc..
Cyst‐based ecotoxicological tests using Anostracans: Comparison of two species ofStreptocephalus
Authors: Crisinei A. , Delaunay L. , Rossel D. , Tarradellas J. , Meyer H. , Saïah H. , Vogel P. , Delisle C. , Blaise C.
Published: October 2006

Cyst‐based ecotoxicological tests are simple and low‐cost methods for assessing acute toxicity. Nevertheless, only a few comparative studies on their sensitivity are known. In the present study, the suitability of the use of two freshwater Anostracan species,Streptocephalus rubricaudatusandS. texanus, was assessed. The impact of 16 priority pollutants (4 heavy metals, 11 organic, and 1 organometallic compounds) on these two species, as well as onArtemia salina(Artoxkit M),Daphnia magna(International Organization for Standardization 6341), andS. proboscideus(Streptoxkit F) was assessed. For indicative comparison, bioassays usingBrachionus calyciflorus(Rotoxkit F) andPhotobacterium phosphoreum(Microtox) were also performed.

For heavy metals (K2Cr2O7, Cd2+, Zn2+, Cu2+), the sensitivity of the two studiedStreptocephalusspecies was slightly higher than that ofD. magna.It was significantly more elevated than for the marineA. salina. For organic and organometallic micropollutants [phenol, 3,5‐dichlorophenol, pentachlorophenol (PCP), hydroquinone, linear alkylbenzene sulfonate, sodium dodecyl sulfate, tributylphosphate, dimethylphthalate, atrazine, lindane, malathion, tributyltin chloride (TBT‐CI)], the sensitivity of the 4 anostracan species was of the same order of magnitude as that ofD. magna. Artemia salinawas slightly less sensitive to some organic compounds (PCP, hydroquinone, TBT‐CI).

The sensitivity ofS. rubricaudatusto organic solvents was low. On the other hand, this anostracan was quite sensitive to NaCI. Thus, its use is restricted to freshwater samples.

The evaluation of global practicability of these two tests confirms that cyst‐based freshwater anostracans may be used to perform low‐cost tests at a sensitivity comparable to that ofD. magna(24 h immobilization test). ©1994 by John Wiley&Sons, Inc..
Rapid methods to assess the effects of chemicals on microbial activity in soil
Authors: Haigh S. D. , Rennie A. F. K.
Published: October 2006

Fluorescein diacetate (FDA) hydrolysis and an automated bacterial impedance technique (RABIT) were compared to the Pseudomonas putida growth inhibition assay (PGI) to assess their suitability as rapid methods to screen for effects of chemicals on soil microbial activity.

RABIT was rapid, was the simplest, and was most convenient of the three methods to perform, but it was an order of magnitude less sensitive to toxicity than FDA or PGI. Further modification of the method may result in a most useful tool for screening purposes.

The FDA hydrolysis method was both simple and rapid to perform. It gave comparable results to the PGI method for 3,5‐dichlorophenol and an amphoteric surfactant, but FDA was an order of magnitude more sensitive to the anionic and nonionic and an order of magnitude less sensitive to the cationic surfactants tested. This apparent conflict emphasizes that the toxicity assessment of a chemical in the environment should not rely entirely on inherent toxicity tests. For terrestrial toxicity testing, interactions between chemical and soil should be taken into account in order to predict correctly the chemical's impact on the environment. For example, adsorption of cationics onto soil particles results in significantly higher concentrations of the chemical being needed in vivo to cause a toxic effect than that predicted by inherent toxicity tests.

The use of soil suspensions in the FDA assay, rather than pure cultures of microorganisms, is a more realistic, but still indirect, test of a chemical's toxicity in soil. When the assay is calibrated against a standard method, such as PGI using uncharged reference chemicals, this method can provide a simple and rapid tool to assess the relative effects of chemicals on soil microbial activity. © 1994 by John Wiley & Sons, Inc..
A simple technique for monitoring mutagenicity and benzo(a)pyrene content in mussels and their ambient water
Authors: Kira Shohei , Taketa Kazuhisa , Nogami Yusaku , Hayatsu Hikoya
Published: October 2006

By hanging blue rayon, an adsorbent specific for chemicals with polycyclic aromatic structures, in seawater for one day, the mutagenicity and the benzo(a)pyrene pollution of the water were monitored. Mussels living in the sites of water sampling were also subjected to the blue rayon extraction process and assayed. The mutagenicity was evaluated by the Salmonella/microsome reversion assay of Ames, with the use of a recently developed sensitive strain YG1024. The monitoring was performed in the Seto Inland Sea at 5 sites near Okayama, in the year 1991–1992. All the water and mussel samples gave positive benzo(a)pyrene contents and many of them showed positive mutagenicity (as assayed with metabolic activation). The mutagenicity and the benzo(a)pyrene contents were found to be significantly correlated both for the water samples and for the mussel samples. In contrast, there were no correlations between the water and the mussel samples regarding either the mutagenicity or benzo(a)pyrene contents. This lack of correlations may be attributed to the fact that the water samples gave results for a one‐day exposure whereas the mussel samples gave those of a long‐term exposure. This simple technique has advantages over the conventional sampling method in terms of easy handling, high sensitivity, and feasibility of monitoring distant sites. © by John Wiley & Sons, Inc.
Quantitative assessment of herbicide decomposition at different initial concentrations
Authors: Stenström John
Published: October 2006

The validity of the equation for first‐order kinetics and of the empirical equation c = c0 ‐ kt1/2 was checked against experimental data on the decomposition of the herbicides linuron and atrazine at different initial concentrations c0, in soil. Standard statistical criteria showed acceptable fits to the data according to first‐order kinetics, but the more stringent criterion of independence of the first‐order rate constant on c0 proved this kinetics to be invalid. The empirical equation gave a better fit to the data. Furthermore, the rate constant k varied linearly with c0 at low c0 and with c1/20 at high c0. Similar relations between k and c0 were also found with 14C‐labeled linuron, when it was found that the curve describing the collected amount of 14C in CO2 consisted of more than one phase. The empirical equation can thus be used to assess quantitatively the influence of various factors on the degradation, using both unlabeled and 14C‐labeled substances.
Anaerobic subsurface soil microcosms: Methods to monitor effects of organic pollutants on indigenous microbial activity
Authors: Dougherty Joel M. , Lanza Guy R.
Published: October 2006

We report the results of an experiment designed to study the effects of organic pollutants on microbial populations indigenous to subsurface soil. Subsurface soil from a pristine short grass prairie, collected aseptically and anaerobically, was used to construct microcosms. The microcosms were divided into three groups: control, biotic chemical, and abiotic chemical. The chemical groups received additions of three organic pollutants in varying concentrations: phenothiazine, chloronapthalene, and polychlorinated biphenyl. The microbial activity of the abiotic chemical group was inhibited with mercuric chloride. The control group received only water. Microbial activity was monitored in all groups using several enzyme assays and a biomass estimate: amylase, dehydrogenase, esterase, phosphatase, protease, and soil protein concentration. Eh and pH were also monitored. Throughout the 32 weeks, overall reducing conditions prevailed in the biotic chemical and control groups. The Eh of the abiotic group remained high. Significant differences were seen among groups in specific enzymatic activities on specific sample dates. However, fluctuating values through time due to succession of microbial consortia made it impossible to make predictions about the overall effects of the pollutants on individual activity measurements. This study is the first report of the effects of a mixture of organic pollutants on microbial consortia indigenous to subsurface soils.
Influence of sulfooxyanions on oxygen uptake, carbon dioxide fixation, and cytochrome reduction in Nitrobacter Agilis
Authors: Tsai Yu‐Li , Tuovinen Olli H.
Published: October 2006

Oxygen uptake coupled with nitrite oxidation by washed cell suspensions was not influenced by persulfate or tetrathionate. Carbon dioxide fixation was insensitive to tetrathionate, and in fact, an enhancement by tetrathionate was observed. Persulfate inhibited the fixation of carbon dioxide only at a high concentration (17 mM S2O2−8). Cytochrome reduction in washed cells of Nitrobacter agilis was demonstrated in the presence and absence of sulfooxyanions. Cytochrome aa3 and cytochrome a1 (α‐peak at 590 nm) were sensitive to sulfooxyanions (sulfite, thiosulfate, metabisulfite, dithionate, persulfate, trithionate, and tetrathionate), whereas cytochrome c (β‐peak at 520 nm) was insensitive to test ions. All sulfooxyanions inhibited the reduction of cytochrome a1 (γ‐peak at 438 nm). This inhibition decreased when the concentration of sulfooxyanions was increased to 17 mM. The reduction of cytochrome c at 550 nm (α‐peak) was blocked by the test ions and the inhibition of cytochrome c at 415 nm (γ‐peak) was also apparent. Complete inhibition of cytochrome c (γ‐peak) was observed in the presence of 17 mM persulfate.
Role of envelopes of gram‐negative bacteria in cadmium binding and toxicity
Authors: Bauda P. , Block J. C.
Published: October 2006

Whole cells, mureinoplasts, and protoplasts of gram‐negative bacteria were used in cadmium biosorption and toxicity determinations. It was shown that whole cells of Pseudomonas fluorescens bind less metal than other bacterial forms, suggesting the outer membrane acts as a barrier toward metals. Such a role was confirmed by toxicity measurements showing a lower toxic effect of cadmium in the presence of the outer membrane. Chemically modified bacteria, with carboxyl groups masked, were used to identify the cadmium binding sites. Results indicate that care is necessary in interpretation since the acid pH used in the blockage reaction was shown to interfere with the cadmium binding. Moreover, the blockage reagents have been shown to modify the cadmium toxicity.
Zinc toxicity to freshwater algae
Authors: Wong P. T. S. , Chau Y. K.
Published: October 2006

Studies with natural phytoplankton from Lake Ontario as well as with pure cultures of two green and one diatom freshwater algal species revealed that the International Joint Commission water quality objective of 30 μg Zn/L was toxic to primary productivity and cell multiplication. The toxicity of Zn varied with its anionic forms, with nitrate being the most toxic, followed by chloride, sulphate, and acetate. Experiments with radioactive 65Zn indicated that Zn was rapidly taken up by the algae, and incorporated mainly into polysaccharide and nucleic acid fractions. These results indicate that an objective for Zn of 30 μg/L is too high to protect algae in the Great Lakes. Based on our results and other published data, a new objective of 10 μg Zn/L has been recommended to the International Joint Commission.
Inhibition of β‐galactosidase biosynthesis in Escherichia coli: Effect of alterations of the outer membrane permeability on sensitivity to environmental toxicants
Authors: Dutton Ronald J. , Bitton Gabriel , Koopman Ben , Agami Orna
Published: October 2006

The use of bacteria as test organisms in rapid ecotoxicity assays is under investigation in several laboratories worldwide. However, little attention has been given to the question of permeability of the outer membrane of gram‐negative bacteria to toxicants of environmental interest. We have investigated the effect of physical, chemical, and genetic alterations on the sensitivity of Escherichia coli to environmental toxicants, as measured via inhibition of β‐galactosidase biosynthesis. Polymyxin treatment (2 mg/L) was the most promising treatment tested, significantly increasing the sensitivity of wild‐type E. coli to pentachlorophenol and sodium dodecyl sulfate. A mutant strain of E. coli (EW1b), with an outer membrane protein alteration (tol C gene), was found to be the most sensitive to hydrophobic compounds and to detergent. EW1b, further sensitized via polymyxin treatment, appears to be a sensitive microorganism for toxicant assay.
Nitrogenase Fe protein‐like Fe–S cluster is conserved in L‐protein (BchL) of dark‐operative protochlorophyllide reductase from Rhodobacter capsulatus
Authors: Nomata Jiro , Kitashima Masaharu , Inoue Kazuhito , Fujita Yuichi
Published: October 2006

Dark‐operative protochlorophyllide reductase (DPOR) in bacteriochlorophyll biosynthesis is a nitrogenase‐like enzyme consisting of L‐protein (BchL‐dimer) as a reductase component and NB‐protein (BchN–BchB‐heterotetramer) as a catalytic component. Metallocenters of DPOR have not been identified. Here we report that L‐protein has an oxygen‐sensitive [4Fe–4S] cluster similar to nitrogenase Fe protein. Purified L‐protein from Rhodobacter capsulatus showed absorption spectra and an electron paramagnetic resonance signal indicative of a [4Fe–4S] cluster. The activity quickly disappeared upon exposure to air with a half‐life of 20 s. These results suggest that the electron transfer mechanism is conserved in nitrogenase Fe protein and DPOR L‐protein.
A novel method for apoptosis protein subcellular localization prediction combining encoding based on grouped weight and support vector machine
Authors: Zhang Zhen-Hui , Wang Zheng-Hua , Zhang Zhen-Rong , Wang Yong-Xian
Published: October 2006

Apoptosis proteins have a central role in the development and homeostasis of an organism. These proteins are very important for understanding the mechanism of programmed cell death. Based on the idea of coarse‐grained description and grouping in physics, a new feature extraction method with grouped weight for protein sequence is presented, and applied to apoptosis protein subcellular localization prediction associated with support vector machine. For the same training dataset and the same predictive algorithm, the overall prediction accuracy of our method in Jackknife test is 13.2% and 15.3% higher than the accuracy based on the amino acid composition and instability index. Especially for the else class apoptosis proteins, the increment of prediction accuracy is 41.7 and 33.3 percentile, respectively. The experiment results show that the new feature extraction method is efficient to extract the structure information implicated in protein sequence and the method has reached a satisfied performance despite its simplicity. The overall prediction accuracy of EBGW_SVM model on dataset ZD98 reach 92.9% in Jackknife test, which is 8.2–20.4 percentile higher than other existing models. For a new dataset ZW225, the overall prediction accuracy of EBGW_SVM achieves 83.1%. Those implied that EBGW_SVM model is a simple but efficient prediction model for apoptosis protein subcellular location prediction.
Complications of Circular Plate Fixation for Four-Corner Arthrodesis
Authors: SHINDLE M. K. , BURTON K. J. , WEILAND A. J. , DOMB B. G. , WOLFE S. W.
Published: October 2006

Four corner arthrodesis is an accepted salvage operation for scapholunate advanced collapse and scaphoid non-union advanced collapse. Circular plates were introduced in 1999 and promoted as a rapid and more stable method for this procedure. A retrospective chart review was performed on all patients who were treated with the Spider Limited Wrist Fusion Plate (Kinetikos Medical Inc., San Diego, CA). Sixteen patients were identified and followed clinically and with X-rays for an average of 16 (range 5–38) months. Nine out of the 16 patients (56%) had complications, including non-union (25%), delayed union (6%), dorsal impingement (25%), radial styloid impingement (6%) and broken screws (13%). The purpose of this study was to compare our complication rate using circular plates with published outcomes using traditional methods of fixation: this study identified a significantly higher complication rate and lower union rate using circular plate fixation for four-corner arthrodesis compared with previously published techniques.
Pontius Pilate and the Imperial Cult in Roman Judaea
Authors: TAYLOR JOAN E.
Published: October 2006

While Pontius Pilate is often seen as agnostic, in modern terms, the material evidence of his coinage and the Pilate inscription from Caesarea indicate a prefect determined to promote a form of Roman religion in Judaea. Unlike his predecessors, in the coinage Pilate used peculiarly Roman iconographic elements appropriate to the imperial cult. In the inscription Pilate was evidently responsible for dedicating a Tiberieum to the Dis Augustis. This material evidence may be placed alongside the report in Philo Legatio ad Gaium (299–305) where Pilate sets up shields – likewise associated with the Roman imperial cult –honouring Tiberius in Jerusalem.
Impossible worlds
Authors: LEFTOW BRIAN
Published: October 2006

Richard Brian Davis offers several criticisms of a semantics I once proposed for subjunctive conditionals with impossible antecedents. I reply to these.
The origin of passive get
Authors: FLEISHER NICHOLAS
Published: October 2006

The history of English passive get is examined, in an attempt to determine both the diachronic pathway of development and the linguistic mechanism of syntactic change. Passive get (as in He got arrested) is shown to have developed from inchoative get (He got sick), and not from causative get (He got himself arrested). Passive get arose in cases where inchoative get took an adjectival passive participle as complement and where viewpoint aspect was perfective. Perfective aspect, which yields a bounded-event reading, encouraged the reanalysis of the adjectival passive participle as a verbal passive participle. Though the pathway of change is the same as that identified by Gronemeyer (1999), the mechanism of change proposed here is novel. The theoretical import of the article is to show how semantic and pragmatic factors like aspect influence morphosyntactic reanalysis, and thereby to raise our expectations about what constitutes a plausible reanalysis and improve our understanding of syntactic change more generally.
The syntax, pragmatics, and prosody of parenthetical what
Authors: DEHÉ NICOLE , KAVALOVA YORDANKA
Published: October 2006

This article contributes to the discussion of parentheticals. It focuses on a specific one-word parenthetical in English, namely what. To account for its distributional behaviour we offer a multifaceted approach. Specifically, our study explains why parenthetical what strongly prefers the position immediately preceding a cardinal number. In this respect, we identify three key questions which can only be answered collectively by looking into its syntactic properties, semantic and pragmatic motivation, and prosodic characteristics. While syntax accounts for parenthetical what being attached to the node that dominates the number, pragmatics takes care of its position immediately preceding the number, and prosody explains the unacceptability of what in sentence-initial position. In this way, this study supports the idea that to fully account for the behaviour of parenthetical structures, the phenomenon should not be restricted to a single component of the grammar. The strength of the present approach also lies in the authenticity and amount of data we used.
Effect of IMF BY on thermospheric composition at high and middle latitudes: 1. Numerical experiments
Authors: Crowley G. , Immel T. J. , Hackert C. L. , Craven J. , Roble R. G.
Published: October 2006

Magnetic storms and their effects on the thermosphere and ionosphere have been studied for many years, yet there are many aspects of the thermospheric and ionospheric responses that are not understood. The purpose of this paper is to show how the high‐latitude composition depends on the sign of the IMF BY component, using controlled simulations with a global first principles model. Because the high‐latitude convection and neutral wind systems are strongly controlled by the IMF BY component, it seems likely that the compositional response that is driven by high‐latitude forcing should also be sensitive to the BY component. To date, no first‐principles modeling has been performed to test the idea of IMF BY effects on composition. Numerical experiments using model simulations provide insight into this important scientific question, since the thermospheric compositional response to the convection patterns for different IMF BZ and BY can be studied in isolation in a model. In this paper we use a first‐principles model to determine the effect of the IMF BY component on the compositional response of the high‐latitude thermosphere. We show for the first time that a clockwise rotation of the potential pattern resulting from a change from BY‐negative to BY‐positive drives a corresponding rotation in the wind, neutral density, and composition distributions. BY control of thermospheric composition has been invoked in the literature to explain an apparent variability in the effectiveness of auroral activity in causing thermospheric storm effects at middle latitudes, as observed in global images of the far‐ultraviolet (FUV) OI 130.4‐nm emission from the DE‐1 auroral imager. However, the effect in the simulations presented here is opposite from that suggested by earlier work based on DE data, indicating another explanation must be sought for the DE results. These simulations are highly relevant for interpreting data being provided by more modern UV imaging instruments on the DMSP, TIMED, and IMAGE satellites.
Effect of IMF By on thermospheric composition at high and middle latitudes: 2. Data comparisons
Authors: Immel Thomas J. , Crowley Geoff , Hackert Chris L. , Craven John D. , Roble Ray G.
Published: October 2006

The strength and orientation of the interplanetary magnetic field (IMF) has a strong effect on the high‐latitude plasma convection pattern, thereby influencing the speed and direction of polar thermospheric winds. The possibility of similar IMF control over the compositional response of the thermosphere during geomagnetic disturbances has not been fully investigated. This study finds that the y‐component of the IMF (IMF By) exerts significant control over the development and subsequent equatorward transport of composition disturbances during periods of heightened geomagnetic activity. This is determined using the NCAR‐TIMEGCM to simulate the thermospheric conditions during the first 3 weeks far‐ultraviolet (FUV) imaging operations of the Dynamics Explorer 1 (DE‐1) mission in 1981. The images reveal changes in the relative thermospheric column abundance of O versus N2 (ΣO/N2). These changes are reproduced by the model, incorporating variable IMF strength and orientation as inputs. It is found that simple reversal of IMF By leads to subsequent changes in ΣO/N2 at middle latitudes by as much as 30%. This is a manifestation of the effect identified in the companion to this report (Crowley et al., 2006). The study confirms the hypothesis of Immel et al. (1997) that IMF‐By effects on middle‐latitude thermospheric composition are important, though more complex than expected. Contrary to previous predictions, early morning local times are shown to be more likely to suffer large decreases in ΣO/N2 when By is negative. However, the overall magnitude of high‐latitude Joule heating is found to be greater when By is positive.
Parameter sensitivity analysis for different complexity land surface models using multicriteria methods
Authors: Bastidas L. A. , Hogue T. S. , Sorooshian S. , Gupta H. V. , Shuttleworth W. J.
Published: October 2006

A multicriteria algorithm, the MultiObjective Generalized Sensitivity Analysis (MOGSA), was used to investigate the parameter sensitivity of five different land surface models with increasing levels of complexity in the physical representation of the vegetation (BUCKET, CHASM, BATS 1, Noah, and BATS 2) at five different sites representing crop land/pasture, grassland, rain forest, cropland, and semidesert areas. The methodology allows for the inclusion of parameter interaction and does not require assumptions of independence between parameters, while at the same time allowing for the ranking of several single‐criterion and a global multicriteria sensitivity indices. The analysis required on the order of 50 thousand model runs. The results confirm that parameters with similar “physical meaning” across different model structures behave in different ways depending on the model and the locations. It is also shown that after a certain level an increase in model structure complexity does not necessarily lead to better parameter identifiability, i.e., higher sensitivity, and that a certain level of overparameterization is observed. For the case of the BATS 1 and BATS 2 models, with essentially the same model structure but a more sophisticated vegetation model, paradoxically, the effect on parameter sensitivity is mainly reflected in the sensitivity of the soil‐related parameters.
Identification of large (2–10 km) rayed craters on Mars in THEMIS thermal infrared images: Implications for possible Martian meteorite source regions
Authors: Tornabene Livio L. , Moersch Jeffrey E. , McSween Harry Y. , McEwen Alfred S. , Piatek Jennifer L. , Milam Keith A. , Christensen Phillip R.
Published: October 2006

Four definitive and three probable rayed craters have been identified on Mars using 100‐m resolution thermal infrared images obtained by the Mars Odyssey Thermal Emission Imaging System (THEMIS). These seven craters are similar to the previously discovered rayed crater Zunil and are best recognized by a distinct thermal contrast with respect to their surroundings. Martian rays, unlike their lunar counterparts, only exhibit minor contrasts in visible albedo. As a consequence, their presence on Mars most likely went unnoticed until substantial global coverage of THEMIS thermal infrared was achieved. Their presence has since been discerned in the coarser‐resolution Thermal Emission Spectrometer (TES) data set, which preceded THEMIS. Observations in visible images of the primary cavities, secondaries, and rays suggest that, like lunar ray counterparts, Martian rays are invariably young geomorphic features. Martian rays are typically greater than hundreds of kilometers in length and consist of numerous densely clustered secondary craters, and thereby are a physical manifestation of high‐velocity ejecta. Spallation accounts for a small fraction of the high‐velocity ejecta that experiences low‐shock compression due to interference from the rarefaction wave with the free surface. Spallation is currently the favored mechanism responsible for ejecting meteorites from Mars and is likely responsible for some of the ray‐forming secondaries. Additional observations and inferences based on Martian rayed craters are compared with current Martian meteorite delivery models and the Martian meteorites themselves. The correlations presented here suggest that Martian rayed craters are the most plausible candidate source craters for the Martian meteorites to date.
Martian craters viewed by the Thermal Emission Imaging System instrument: Double‐layered ejecta craters
Authors: Boyce Joseph M. , Mouginis‐Mark Peter J.
Published: October 2006

The Thermal Emission Imaging System (THEMIS) visible (VIS) images provide new insight into the nature and development of the unique ejecta deposits of Martian craters. This study focuses on double‐layered ejecta (DLE) craters. To date, over 100 DLE craters have been examined using mainly THEMIS VIS data. Our observations suggest that emplacement of DLE crater ejecta occurred in two stages, with the inner ejecta layer emplaced similar to single‐layered ejecta (SLE) crater ejecta. This may have involved both ballistic and flow processes. In contrast, the outer ejecta layer of DLE craters appears to have been emplaced through the high‐velocity outflow of materials from tornadic winds generated by the advancing ejecta curtain or base surge. Remarkably, DLE craters lack secondary craters, which suggests that the large ejecta blocks that normally produce such craters may have either been entrained and/or crushed by these winds or fragmented as a result of the presence of water in the target materials. These observations suggest that volatiles (either trapped in the subsurface or in the atmosphere) have played a key role in the emplacement of the ejecta of DLE craters and leaves open the question as to what role volatiles play in the emplacement of ejecta of other types of fluidized ejecta craters (i.e., SLE and MLE craters). Because DLE craters are found in many different regions of Mars, often in close proximity to other types of craters, conditions (e.g., atmospheric density) that produce DLE craters must fluctuate or the Martian crust must be unexpectedly heterogeneous (laterally and vertically). While the degree of heterogeneity has yet to be recognized, recent suggestions about possible Martian climate change raises the possibility of impact into target materials that are periodically wet or that a significantly higher atmospheric pressure may be periodically present.
Dune migration and slip face advancement in the Rabe Crater dune field, Mars
Authors: Fenton Lori K.
Published: October 2006

Eight overlapping images of a dune slip face in Rabe Crater (35°E, 44°S) from the Mars Global Surveyor Mars Orbiter Camera show changes interpreted to be multiple grainflow events that would indicate present‐day sand saltation and dune migration. New occurrences of these features appear sporadically throughout late southern summer and early fall, and then no further changes occur throughout winter. By the following summer the pattern of old streaks had been almost completely covered by new dark streaks. Assuming that this activity is typical from year to year, migration rates are estimated to be on the order of 1–2 cm per martian year, produced by south to southeasterly winds that blow mostly during the southern spring and early summer. This slow migration rate is consistent with a present‐day sediment state that is either transport or availability limited.
First tomographic image of ionospheric outflows
Authors: Yizengaw E. , Moldwin M. B. , Dyson P. L. , Fraser B. J. , Morley S.
Published: October 2006

An image of the dayside low‐energy ion outflow event that occurred on 16 December 2003 was constructed with ground‐ and space‐based GPS (Global Positioning System) Total Electron Content (TEC) data and ion drift meter data from the DMSP (Defense Meteorological Satellite Program). A tomographic reconstruction technique has been applied to the GPS TEC data obtained from the GPS receiver on the Low Earth Orbit (LEO) satellite FedSat. The two dimensional tomographic image of the topside ionosphere and plasmasphere reveals a spectacular beam‐like dayside ion outflow emanating from the cusp region. The transverse components of the magnetic field in FedSat's NewMag data show the presence of field aligned current (FAC) sheets, indicating the existence of low‐energy electron precipitation in the cusp region. The DMSP ion drift data show upward ion drift velocities and upward fluxes of low‐energy ions and electrons at the orbiting height of the DMSP spacecraft in the cusp region. This study presents the first tomographic image of the flux tube structure of ionospheric ion outflows from 0.13 Re up to 3.17 Re altitude.
Inhalational Anesthetics as Neuroprotectants or Chemical Preconditioning Agents in Ischemic Brain
Authors: Kitano Hideto , Kirsch Jeffrey R , Hurn Patricia D , Murphy Stephanie J
Published: October 2006

This review will focus on inhalational anesthetic neuroprotection during cerebral ischemia and inhalational anesthetic preconditioning before ischemic brain injury. The limitations and challenges of past and current research in this area will be addressed before reviewing experimental and clinical studies evaluating the effects of inhalational anesthetics before and during cerebral ischemia. Mechanisms underlying volatile anesthetic neuroprotection and preconditioning will also be examined. Lastly, future directions for inhalational anesthetics and ischemic brain injury will be briefly discussed.
Time-resolved x-ray pinhole camera with grazing incidence mirror to eliminate bremsstrahlung noise signal on Z
Authors: Nash T. J. , Chandler G. A. , Bailey J. E. , Rochau G. , Leeper R. J. , Nielsen D. S. , Moore T.
Published: October 2006

An on-axis time-resolved x-ray pinhole camera has been used on the 20MA 100ns driver Z to image the converging shock wave in dynamic Hohlraum experiments and to image pellet hot spots in inertial confinement fusion implosions. This instrument is susceptible to detecting significant amounts of pinch bremsstrahlung radiation with energies at hundreds of keV and yields of roughly 1kJ. Quite often the bremsstrahlung noise signals have overwhelmed the desired x-ray images. In an effort to eliminate this large source of noise we have incorporated a 6° gold-coated grazing incidence mirror into the time-resolved x-ray pinhole camera system. The mirror reflects soft x rays at energies under 2keV but does not reflect bremsstrahlung radiation at hundreds of keV. We will present data from the instrument without the mirror showing large amounts of bremsstrahlung noise contamination and data with the mirror in the system showing greatly reduced noise levels.
Photon Landau damping of electron plasma waves with photon recoil
Authors: Mendonça J. T. , Serbeto A.
Published: October 2006

Photon Landau damping of electron plasma waves with relativistic phase velocity is described, using a photon kinetic theory where photon recoil is taken into account. An exact form of the wave kinetic equation is used. Kinetic and fluid regimes of photon beam instabilities are discussed. Diffusion in the photon momentum space is derived and a quasilinear wave kinetic equation is established. In the present approach, photon recoil effects associated with the emission or absorption of plasmons are included. The neglect of recoil, which is equivalent to using the geometric optics approximation, reduces the present results to those already existing in the literature.
Fractional Hamiltonian analysis of higher order derivatives systems
Authors: Baleanu Dumitru , Muslih Sami I. , Taş Kenan
Published: October 2006

The fractional Hamiltonian analysis of 1+1 dimensional field theory is investigated and the fractional Ostrogradski’s formulation is obtained. The fractional path integral of both simple harmonic oscillator with an acceleration-squares part and a damped oscillator are analyzed. The classical results are obtained when fractional derivatives are replaced with the integer order derivatives.
Infrared plus vacuum ultraviolet spectroscopy of neutral and ionic methanol monomers and clusters: New experimental results
Authors: Hu Y. J. , Fu H. B. , Bernstein E. R.
Published: October 2006

We present new observations of the infrared (IR) spectrum of neutral methanol and neutral and protonated methanol clusters employing IR plus vacuum ultraviolet (vuv) spectroscopic techniques. The tunable IR light covers the energy ranges of 2500–4500cm−1 and 5000–7500cm−1. The CH and OH fundamental stretch modes, the OH overtone mode, and combination bands are identified in the vibrational spectrum of supersonic expansion cooled methanol (2500–7500cm−1). Cluster size selected IR plus vuv nonresonant infrared ion-dip infrared spectra of neutral methanol clusters, (CH3OH)n (n=2,…,8), demonstrate that the methanol dimer has free and bonded OH stretch features, while clusters larger than the dimer display only hydrogen bonded OH stretch features. CH stretch mode spectra do not change with cluster size. These results suggest that all clusters larger than the dimer have a cyclic structure with OH groups involved in hydrogen bonding. CH groups are apparently not part of this cyclic binding network. Studies of protonated methanol cluster ions (CH3OH)nH+ n=1,…,7 are performed by size selected vuv plus IR photodissociation spectroscopy in the OH and CH stretch regions. Energies of the free and hydrogen bonded OH stretches exhibit blueshifts with increasing n, and these two modes converge to approximately 3670 and 3400cm−1 at cluster size n=7, respectively.
On Hall magnetohydrodynamics equilibria
Authors: Throumoulopoulos G. N. , Tasso H.
Published: October 2006

Steady states are studied in the framework of the ideal Hall magnetohydrodynamics (HMHD) model in arbitrary and axisymmetric geometries. In arbitrary geometry, conditions are found under which certain magnetohydrodynamics (MHD) equilibrium solutions can also satisfy the HMHD equations. For axisymmetric plasmas reduced equations are derived for uniform electron temperatures on magnetic surfaces and either barotropic ions or incompressible ion flows. The Hall and electron pressure gradient terms result in a deviation of the magnetic from the ion velocity surfaces, and consequently, the axisymmetric equilibria obey a set of coupled partial differential equations: one for the poloidal magnetic flux function and the other for a flux function labeling the ion velocity surfaces. Furthermore, the characteristics of certain classes of axisymmetric steady states with side conditions, as flows parallel to the magnetic field or purely poloidal incompressible flows, are identified and compared with respective MHD equilibria. Unlike in the frame of MHD, steady states with parallel axisymetric flows must be incompressible and equilibria with purely poloidal incompressible flows are possible. Certain analytic axisymmetric solutions are also constructed.
Conformational disorder of conjugated polymers
Authors: Westenhoff Sebastian , Beenken Wichard J. D. , Yartsev Arkady , Greenham Neil C.
Published: October 2006

Conformational disorder of conjugated polymers is an important issue to be understood and quantified. In this paper we present a new method to assess the chain conformation of conjugated polymers based on measurements of intrachain energy transfer. The chain conformation is modeled on the basis of monomer-monomer interactions, such as torsion, bending, and stretching of the connecting bond. The latter two potentials are assumed to be harmonic, while the torsional potential was calculated by density functional theory using B3-LYP functional with the SVP basis set. The energy transfer dynamics of excitons on these chains are quantitatively simulated using Förster-type line-dipole energy transfer. This allows us to compare the simulated ground state conformation of single polymer chains to ultrafast depolarization experiments of poly [3-(2,5-dioctylphenyl)thiophene] in solution. We identify torsional rotation as the main contributor to conformational disorder and find that this disorder is mainly controlled by the energy difference between syn and anti bonds.
Effects of shock waves on spatial distribution of proton beams in ultrashort laser-foil interactions
Authors: Xu M. H. , Li Y. T. , Yuan X. H. , Yu Q. Z. , Wang S. J. , Zhao W. , Wen X. L. , Wang G. C. , Jiao C. Y. , He Y. L. , Zhang S. G. , Wang X. X. , Huang W. Z. , Gu Y. Q. , Zhang J.
Published: October 2006

The characteristics of proton beam generated in the interaction of an ultrashort laser pulse with a large prepulse with solid foils are experimentally investigated. It is found that the proton beam emitted from the rear surface is not well collimated, and a “ring-like” structure with some “burst-like” angular modulation is presented in the spatial distribution. The divergence of the proton beam reduces significantly when the laser intensity is decreased. The “burst-like” modulation gradually fades out for the thicker target. It is believed that the large divergence angle and the modulated ring structure are caused by the shock wave induced by the large laser prepulse. A one-dimensional hydrodynamic code, MED103, is used to simulate the behavior of the shock wave produced by the prepulse. The simulation indicates that the rear surface of the foil target is significantly modified by the shock wave, consequently resulting in the experimental observations.
The Weibel instability on strongly magnetized microwave produced plasma
Authors: Ghorbanalilu M.
Published: October 2006

The electron distribution function (EDF) of plasma generated due to the interaction between a circularly polarized intense microwave (MW) field with a dilute gas is investigated in the presence of a static magnetic field. Making use of the EDF, the electron dielectric permittivity tensor is obtained. Taking into account the anisotropic structure of EDF, it is evident that the Weibel instability can occur in such plasmas. Therefore, using the adiabatic approximation, the dispersion relation is obtained for small electron perturbations across the MW field. By solving the dispersion relation, it is shown that not only does the magnetic field decrease the growth rate of the Weibel instability, but that a sufficiently strong magnetic field can make the instability completely disappear.
Dynamics of turbulent transport in the scrape-off layer of the CASTOR tokamak
Authors: Devynck P. , Brotankova J. , Peleman P. , Spolaore M. , Figueiredo H. , Hron M. , Kirnev G. , Martines E. , Stockel J. , Van Oost G. , Weinzettl V.
Published: October 2006

In this paper, the propagation of turbulent events along radial and poloidal probe arrays in the scrape-off layer (SOL) of the tokamak CASTOR [M. Hron et al., Czech. J. Phys. 49, 181 (1999)] is observed using a novel correlation technique. The typical turbulent structures appear as dipoles on the floating potential signals and as positive bursts on the density. It is found that both dipoles and density bursts propagate over long radial distances in the SOL while propagating poloidally. A comparison of the measured velocities of the potential and density fluctuations shows that the density structures move radially faster than the potential ones. This allows us to understand how the density is convected by the turbulence. The density moves radially along the potential valleys created by the poloidal dipoles without modifying them. In the framework of an interchange turbulence, this property indicates that charge exchange collisions with neutrals in the SOL of CASTOR lead to a high viscosity that damps the zonal flows.
Determination of polarization charge density on interface of AlGaN∕GaN heterostructure by electroreflectance
Authors: Wang Dong-Po , Wu Chi-Chang , Wu Chia-Chun
Published: October 2006

Electroreflectance spectra of AlGaN∕GaN heterostructure were obtained at various bias voltages (Vdc). Franz-Keldysh oscillations (FKOs) were observed above band gap of AlGaN. The strength of electric field in AlGaN (FAlGaN) was evaluated from the periods of the FKOs, yielding the strength of FAlGaN as a function of Vdc. A positive fixed polarization charge σp arises as a result of the polarization discontinuity across the heterointerface. The neighboring electrons are then attracted by the established σp to form a two-dimensional electron gas (2DEG) at the interface. The experimental value of σp, as obtained by completely depleting the 2DEG using a negative Vdc, is found to be reasonably close to the theoretical value.