bluuebunny/crossref_metadata_2025 huggingface dataset:
Retracted: Epidemiological evaluation of intraoperative antibiosis as a protective agent against endophthalmitis after cataract surgery
Authors: Krummenauer Frank , Kurz Sabine , Dick H. Burkhard
Published: July 2006

Purpose

To evaluate risk factors for endophthalmitis after cataract surgery and to retest recent findings on the protective effect of intraoperative antibiosis and the promoting effect of the clear corneal as compared to sclerocorneal incision.

Design

Survey study.

Participants

Five hundred thirty‐eight ophthalmosurgical centers in Germany.

Main Outcome Measure

Responder specific endophthalmitis incidence.

Results

A total of 310 (58%) questionnaires were computed resulting in an overall count of 404 356 cataract surgeries and 291 self‐reported endophthalmitis cases (crude rate 0.072%). The risk of postoperative endophthalmitis for sclerocorneal versus clear corneal incisions was not significantly reduced (relative risk 0.97, 99% confidence interval 0.69–1.38). The hypothesis of a protective effect of intraocular antibiosis could be confirmed by a significantly decreased risk ratio of 0.69 (99% confidence interval 0.48–0.99) indicating a significant benefit from intraoperative intraocular antibiosis. A similar tendency was observed for an intraoperative periocular antibiosis with a significantly reduced risk ratio of 0.68 (99% confidence interval 0.49–0.96). These risk estimates had been adjusted for the size of the surgical center: a significantly reduced risk ratio of 0.70 (99% confidence interval 0.49–0.98) for postoperative endophthalmitis was observed for local centers.

Conclusions

Whereas this 2001 appraisal of a survey in 1996 could not reproduce the benefit of sclerocorneal incision, the protective effect of intraoperative intraocular antibiotic prophylaxis could be confirmed. However, the results of this survey have to be interpreted with care, since it is not based on individual case information, but rather on aggregate questionnaire data. Copyright © 2006 John Wiley & Sons, Ltd.
Feeding and attraction of non‐target flies to spinosad‐based fruit fly bait
Authors: Wang Xin‐Geng , Messing Russell H
Published: July 2006

A spinosad‐based fruit fly bait, GF‐120, has recently become a primary tool for area‐wide suppression or eradication of pest tephritid fruit flies. The present study assessed the attraction and feeding of five non‐target fly species to GF‐120 in Hawaii. These non‐target flies include three beneficial tephritid species [Eutreta xanthochaeta (Aldrich), Tetreuaresta obscuriventris (Loew), Ensina sonchi (L.)] introduced for weed biological control, an endemic Hawaiian tephritid [Trupanea dubautiae (Bryan)] (all Diptera: Tephritidae) and the cosmopolitan Drosophila melanogaster Meigen (Diptera: Drosophilidae). All five non‐target fly species were susceptible to GF‐120, as was the target pest Mediterranean fruit fly Ceratitis capitata (Wiedemann). Feeding on, or even brief tasting of, GF‐120 killed all fly species within 2 h. When individual flies were provided with a choice of GF‐120 or honey solution, there was no difference in the frequency of first food encounter by E. xanthochaeta, D. melanogaster or C. capitata. The other three non‐target species approached honey more often than GF‐120 in their first food encounter. Feeding times on GF‐120 and honey were not significantly different for D. melanogaster and C. capitata, while the other four non‐target species fed longer on honey than on GF‐120. There was no significant difference in feeding time on honey versus GF‐120 between males and females of each species. These results suggest that area‐wide treatment using GF‐120 for the purpose of eradication of pest fruit flies has potential negative impacts on these and other non‐target fly species in Hawaii. Copyright © 2006 Society of Chemical Industry
I‐conotoxin superfamily revisited
Authors: Mondal Sukanta , Babu Rajasekaran Mohan , Bhavna Rajasekaran , Ramakumar Suryanarayanarao
Published: July 2006

The I‐conotoxin superfamily (I‐Ctx) is known to have four disulfide bonds with the cysteine arrangement C‐C‐CC‐CC‐C‐C, and the members inhibit or modify ion channels of nerve cells. Recently, Olivera and co‐workers (FEBS J. 2005; 272: 4178–4188) have suggested that the previously described I‐Ctx should now be divided into two different gene superfamilies, namely, I1 and I2, in view of their having two different types of signal peptides and exhibiting distinct functions. We have revisited the 28 entries presently grouped as I‐Ctx in UniProt Swiss‐Prot knowledgebase, and on the basis of in silico analysis have divided them into I1 and I2 superfamilies. The sequence analysis has provided a framework for in silico annotation enabling us to carry out computer‐based functional characterization of the UniProtKB/TrEMBL entry Q59AA4 from Conus miles and to predict it as a member of the I2 superfamily. Furthermore, we have predicted the mature toxin of this entry and have proposed that it may be an inhibitor of voltage‐gated potassium channels. Copyright © 2006 European Peptide Society and John Wiley & Sons, Ltd.
The effects of Anethum graveolens L. on female reproductive system
Authors: Monsefi M. , Ghasemi M. , Bahaoddini A.
Published: July 2006

The effects of Anethum graveolens L. (dill) extracts on the female reproductive system were studied in 54 Wistar female rats with regular estrous cycle in six groups. The experimental groups were fed with 0.045 g/kg and 0.45 g/kg of aqueous extract, 0.5 g/kg and 5 g/kg of ethanol extract for 10 days. The sham group was fed with solvent and the controls received no treatment. The estrous cycle changes were determined by daily vaginal smear changes. At the beginning and at the end of the experiment blood samples were provided to determine the blood estradiol and progesterone concentration. The ovaries were prepared histologically and the volume of different follicles was estimated. A significant increase was observed in the duration of the estrous cycle and in the diestrus phase and the progesterone concentration in high dose extract treatment. The stereological study did not reveal any significant changes in the volumes of ovaries, primary, secondary and graafian follicles. Dill can be used either as a regulatory agent of the menstrual cycle for women with irregular cycles or as an antifertility agent. More studies are needed to clarify the properties of this herb. Copyright © 2006 John Wiley & Sons, Ltd.
Retracted: Effects of thymoquinone (volatile oil of black cumin) on rheumatoid arthritis in rat models
Authors: Tekeoglu Ibrahim , Dogan Ali , Demiralp Levent
Published: July 2006

Many studies have been carried out in recent years on the pharmacological effects of nigella sativa seeds that have uncovered their antiinflammatory and immunological effects. The objective of this study was to explore the antiinflammatory effects of thymoquinone on arthritis in rat models. Rats with arthritis induced by Freund's incomplete adjuvant were assigned into five groups: group 1: controls 0.9% NaCl (n = 7); group 2: 2.5 mg/kg thymoquinone (n = 7); group 3: 5 mg/kg thymoquinone (n = 7); group 4: Bacilli Chalmette Guerin (BCG) 6 × 105 CFU (n = 7); group 5: methotrexate 0.3 mg/kg (n = 7). Signs of inflammation on the claw and radiological signs were searched for and TNF‐alpha and IL‐1beta were measured. The results of control and other groups were compared. As a result, thymoquinone, confirmed clinically and radiologically, suppressed adjuvant‐induced arthritis in rats. Copyright © 2006 John Wiley & Sons, Ltd.
Fluorous 2,4‐Dichloro‐1,3,5‐triazine (F‐DCT) as an Amide Coupling Agent
Authors: Zhang Wei , Lu Yimin
Published: July 2006

1H,1H,2H,2H,3H,3H‐perfluoroundecanol displaced 2,4‐dichloro‐1,3,5‐triazine 5 is synthesized and used as a condensation agent for amide synthesis. Two active sites on the triazine ring lead to formation of two equivalents of amidation products. The purification of reaction mixtures is accomplished by plate‐to‐plate fluorous solid‐phase extraction.
Rapid Oligosaccharide and Peptide Syntheses on a Recyclable Fluorous Support
Authors: Mizuno Mamoru , Goto Kohtaro , Miura Tsuyoshi , Inazu Toshiyuki
Published: July 2006

A hexakisfluorous chain‐type alcohol 7 was used in the synthesis of oligosaccharide and peptides through connection with a linker suitable for the particular type of target compound. After the preparation of the desired compound, the fluorous alcohol was easily recovered in good yields under basic conditions. It appears that the fluorous alcohol can be recovered, recycled, and reused.
Latent‐variable models for longitudinal data with bivariate ordinal outcomes
Authors: Todem David , Kim KyungMann , Lesaffre Emmanuel
Published: July 2006

We use the concept of latent variables to derive the joint distribution of bivariate ordinal outcomes, and then extend the model to allow for longitudinal data. Specifically, we relate the observed ordinal outcomes using threshold values to a bivariate latent variable, which is then modelled as a linear mixed model. Random effects terms are used to tie all together repeated observations from the same subject. The cross‐sectional association between the two outcomes is modelled through the correlation coefficient of the bivariate latent variable, conditional on random effects. Assuming conditional independence given random effects, the marginal likelihood, under the missing data at random assumption, is approximated using an adaptive Gaussian quadrature for numerical integration. The model provides fixed effects parameters that are subject‐specific, but retain the population‐averaged interpretation when properly scaled. This is particularly well suited for the situation in which population comparisons and individual level contrasts are of equal importance. Data from a psychiatric trial, the Fluvoxamine (an antidepressant drug) study, are used to illustrate the methodology. Copyright © 2006 John Wiley & Sons, Ltd.
Shifts in foci and priorities. Different relevance of requirements to changing goals yields conflicting prioritizations and is viewpoint‐dependent
Authors: Hoorn Johan F. , Breuker Mark E. , Kok Evelien
Published: July 2006

Stakeholders judge goal relevance and software–development project requirements differently, considering them from a business versus a personal viewpoint. Three empirical studies provided evidence that stakeholders' personal goals for a system are valued higher than business goals and that, moreover, changes in personal goals lead to significantly more prioritization activity than changes in business goals. In Study 1, police officers expressed their agreement to a list of requirements on a Capacity Management System from a business and a personal viewpoint. We found a ‘requirements‐analysis rift,’ indicating that stakeholders regard requirements as business‐related, agreeing with them even if these requirements do not match their personal goals. In Study 2, science students rank‐ordered the same list of requirements on an e‐learning environment from a university and a personal perspective. In Study 3, we conducted a similar study with a sample of financial consultants. The latter two studies revealed that, when personal goals changed, prioritization shifts were stronger than when business goals changed. In addition, we suggest a method using the Spearman rho statistic to calculate changes in requirements prioritization under different conditions of goal change. Copyright © 2006 John Wiley & Sons, Ltd.
Acetabular Fractures in the Elderly: Treatment Recommendations
Authors: Pagenkopf Eric , Grose Andrew , Partal George , Helfet David L.
Published: July 2006

Acetabular fractures in the elderly population are marked by a high degree of variability in terms of patient and fracture characteristics. Successful outcomes depend on application of highly individualized management principles by experienced teams. Reviewed are indications and outcomes associated with various management options, including closed treatment, open reduction internal fixation, and acute or staged total hip arthroplasty. Proper initial management choices are critical, as early failures and subsequent salvage surgery can be accompanied by significant morbidity. Clinical results after ORIF closely follow the quality of articular reduction and the ability to maintain a congruent reduction of the hip joint. Fracture characteristics predictive of anatomic articular reduction should be treated with ORIF. Fracture characteristics predictive of early post-traumatic arthritis should be treated with simultaneous ORIF and THA. Presented is one referral institution's treatment algorithm and management approach.
Stabilising normal and mis‐sense variant α‐glucosidase
Authors: Kakavanos Revecca , Hopwood John J. , Lang Debbie , Meikle Peter J. , Brooks Doug A.
Published: July 2006

α‐Glucosidase (EC 3.2.1.3) is a lysosomal enzyme that hydrolyses α‐1,4‐ and α‐1,6‐linkages of glycogen to produce free glucose. A deficiency in α‐glucosidase activity results in glycogen storage disorder type II (GSD II), also called Pompe disease. Here, d‐glucose was shown to be a competitive inhibitor of α‐glucosidase and when added to culture medium at 6.0 g/L increased the production of this protein by CHO‐K1 expression cells and stabilised the enzyme activity. d‐Glucose also prevented α‐glucosidase aggregation/precipitation and increased protein yield in a modified purification scheme. In fibroblast cells, from adult‐onset GSD II patients, d‐glucose increased the residual level of α‐glucosidase activity, suggesting that a structural analogue of d‐glucose may be used for enzyme enhancement therapy.
Theism and modal realism
Authors: SHEEHY PAUL
Published: July 2006

This paper examines the relationship between the classical theistic conception of God and modal realism. I suggest that realism about possible worlds has unwelcome consequences for that conception. First, that modal realism entails the necessity of divine existence eludes explanation in a way congenial to a commitment to both modal realism and classical theism. Second, divine knowledge is dependent on worlds independent of the creative role and action of God, thereby suggesting a limitation on the nature of divine knowledge and on the nature of God's creative role. Third, modal realism indicates the existence of real, albeit non-actual, worlds of appalling evil threatening the classical conception of divine omnipotence and benevolence.
AN ECONOMIC MODEL OF SCIENTIFIC RULES
Authors: FERREIRA JOSÉ LUIS , ZAMORA-BONILLA JESÚS
Published: July 2006

Empirical reports on scientific competition show that scientists can be depicted as self-interested, strategically behaving agents. Nevertheless, we argue that recognition-seeking scientists will have an interest in establishing methodological norms which tend to select theories of a high epistemic value, and that these norms will be still more stringent if the epistemic value of theories appears in the utility function of scientists, either directly or instrumentally.
FAIR BIAS
Authors: SEGAL UZI
Published: July 2006

This paper takes a simple, informal suggestion by Broome and another more explicit suggestion by Kamm for how to deal with asymmetric claims and shows how they can be interpreted to be consistent with two different social welfare functions: Sum-of-square-roots of individual utilities, and product of utilities. These functions are then used to analyze more complicated situations but I show that the first yields more intuitive results, and a better compromise of efficiency and justice, than the other.
ECONOMIC (IR)RATIONALITY IN RISK ANALYSIS
Authors: HANSSON SVEN OVE
Published: July 2006

Mainstream risk analysis deviates in at least two important respects from the rationality ideal of mainstream economics. First, expected utility maximization is not applied in a consistent way. It is applied to endodoxastic uncertainty, i.e. the uncertainty (or risk) expressed in a risk assessment, but in many cases not to metadoxastic uncertainty, i.e. uncertainty about which of several competing assessments is correct. Instead, a common approach to metadoxastic uncertainty is to only take the most plausible assessment into account. This will typically lead to risk-prone deviations from risk-neutrality. Secondly, risks and benefits for different persons are added to form a total value of risk. Such calculations are used to support the view that one should accept being exposed to a risk if it brings greater benefits for others. This is in stark contrast to modern Paretian welfare economics, that refrains from interindividual comparisons and does not require people to accept a disadvantage because it brings a larger advantage for others.
Lev Dodin and the Maly Drama Theatre: Uncle Vanya to King Lear
Authors: Shevtsova Maria
Published: July 2006

Audiences who marvelled at the Maly Theatre’s Uncle Vanya during its 2005 UK tour will be astonished to discover Sergey Kuryshev and Pyotr Semak, Vanya and Astrov respectively, transformed virtually beyond recognition in King Lear, the Maly’s most recent production. Lear, here briefly previewed by Maria Shevtsova, will be performed at the Barbican Centre in London from 10 to 14 October 2006, and plans are under way for it to travel elsewhere in the country. The Maly Drama Theatre – Theatre of Europe (its full title since 1998) has developed a unique approach in both rehearsing and performing its productions. These include such works as Brothers and Sisters (1985), devised from the novel by Fyodor Abramov, and Dostoevsky’s The Devils (1991). Maria Shevtsova, Co-Editor of New Theatre Quarterly, is Professor of Drama and Theatre Arts at Goldsmiths College, University of London. This article sustains her work on the Maly begun in Dodin and the Maly Drama Theatre: Process to Performance (Routledge, 2004).
Aggregation and coexistence of dung beetles in montane rain forest and deforested sites in central Peru
Authors: Horgan Finbarr G.
Published: July 2006

The ‘aggregation model of coexistence’ predicts that a strong and independent aggregation of species across ephemeral resource patches promotes species coexistence and maintains diversity. This study examines the role of aggregation in maintaining tropical dung beetle diversity and the effects of deforestation on aggregation patterns and diversity loss. Using clusters of pitfall traps, dung beetle aggregation was quantified in natural and disturbed habitat at nested temporal and spatial scales in central Peru. The results indicate that dung was colonized by a greater number of species, many of which were large, leading to a higher total beetle biomass in forest habitat than in deforested, farm habitat. Beetles were intraspecifically aggregated at each spatial scale examined. Habitat-type (forest/deforested) had no effect on the intensity of intra- or interspecific aggregation. Analyses of aggregation patterns revealed that dung beetle assemblages in forest habitat were generally saturated whereas in deforested habitat they were unsaturated. In general, interspecific aggregation was too weak relative to intraspecific aggregation to explain the high diversity of species in forest habitat. Other mechanisms, including resource partitioning are likely to play a greater role in maintaining the diversity of dung beetle assemblages in the region. These results also indicate that the loss of species from disturbed habitat has not been due to a breakdown in the aggregation mechanism.
Distance effect from cloud forest fragments on plant community structure in abandoned pastures in Veracruz, Mexico
Authors: Muñiz-Castro Miguel Angel , Williams-Linera Guadalupe , Benayas José María Rey
Published: July 2006

Secondary succession was studied in a Mexican cloud forest region along a chronosequence of 15 abandoned pastures (0.25–80 y). Our objective was to determine the effects of distance from the forest border on successional vegetation structure and woody species richness along the chronosequence. Vegetation structure similar to that of mature forests recovered over 40–50 y, both close to (0–10 m) and away from (40–50 m) the border. Total woody species richness was similar for both distances but species composition differed significantly. When primary forest species were analysed separately, basal area, height, abundance and richness were all significantly higher close to the forest border. Primary species such as Quercus spp. (barochorous-synzoochorous) and Carpinus caroliniana (anemochorous) had lower basal area, density and height away from the border than close to it. Secondary species such as Lippia myriocephala (anemochorous) and Myrsine coriacea (endozoochorous) did not differ in their rate of colonization between distances. The limitation of seed dispersal and establishment for primary woody species away from forest borders suggests that propagules need to be introduced to accelerate forest restoration.
Nutritional ecology of elephants in Kibale National Park, Uganda, and its relationship with crop-raiding behaviour
Authors: Rode Karyn D. , Chiyo Patrick I. , Chapman Colin A. , McDowell Lee R.
Published: July 2006

This study investigated the nutritional ecology of forest elephants in Kibale National Park, Uganda relative to crop-raiding behaviour, and examined nutritional differences between crops and food consumed by wild elephants. An index of dietary nutrient concentration was determined by quantifying the species and parts of plants consumed along feeding trails, collecting food items, and analysing foods for energy, fibre, protein, minerals and secondary compounds. Frequency of crop raiding was quantified over 13 mo. Energy and protein concentration was within suggested levels, but concentrations of several minerals, particularly sodium, were low relative to requirements based on captive elephants and values reported for other wild populations. The very low sodium concentrations of Kibale elephant diets and low availability of alternative sodium sources, such as soil or water, suggest that sodium drive is very likely in this population. Crops consumed by Kibale elephants had higher Na concentrations and lower concentrations of fibre and secondary compounds than wild diets. The known attraction of elephants to mineral sources throughout their range and the low mineral concentration of leaves, fruits, bark, and stems consumed by forest elephant in this study suggest that mineral nutrition is likely to be an important factor driving elephant behaviour and patterns of habitat use.
Juvenile mortality and attacks by a specialist herbivore increase with conspecific adult basal area of Amazonian Swietenia macrophylla (Meliaceae)
Authors: Norghauer Julian M. , Malcolm Jay R. , Zimmerman Barbara L.
Published: July 2006

According to the Janzen–Connell model, host-specific natural enemies can promote species coexistence of canopy trees in tropical forests by attacking progeny where they are most concentrated. However, empirical evidence relating negative density-dependent mortality to herbivory and, in particular, attack by specialist herbivores, remains rare. We investigated density dependence in a natural population of Swietenia macrophylla in a south-eastern Amazon forest of Brazil. Across 24 adult trees, we found that initial juvenile densities were positively correlated with basal area of adult conspecifics whereas subsequent survivorship over 1 y for these juveniles declined strongly with increasing basal area of adult conspecifics. For 18 trees with > 5 juveniles surviving for 1 y, further evidence supporting the Janzen–Connell mechanism was obtained in that leaf herbivory and attack by a specialist microlepidopteran moth (Steniscadia poliophaea) increased, and overall foliar condition decreased, with conspecific basal area. Moreover, when differences in mean juvenile size (number of extant leaves) were accounted for, juvenile survival over 1 y decreased with increased specialist leaf herbivory. Collectively, these results indicate that herbivores, in particular S. poliophaea, may contribute to density dependence among S. macrophylla juveniles. We conclude that the survival of juveniles and their probability of recruitment into the canopy is decreased where conspecific adults are largest and/or most numerous and find support for the importance of host-specific pests in driving density dependence among tropical trees.
Trophic ecology of a tropical aquatic and terrestrial food web: insights from stable isotopes (15N)
Authors: Kupfer Alexander , Langel Reinhard , Scheu Stefan , Himstedt Werner , Maraun Mark
Published: July 2006

We used stable isotope analysis (15N/14N) to characterize the trophic relationships of consumer communities of an aquatic food web (a permanent pond) and the adjacent terrestrial food web (secondary dry dipterocarp forest) from a seasonal tropical field site in north-eastern Thailand. In general, isotopic signatures of aquatic vertebrates were higher (δ15N range = 4.51–9.90‰) than those of invertebrates (δ15N range = 1.10–6.00‰). High 15N signatures identified water snakes and swamp eels as top predators in the pond food web. In the terrestrial food web 15N signatures of saprophagous litter invertebrates (diplopods, earthworms), termites, ants and beetle larvae were lower than in those of predatory invertebrates (scolopendrids, scorpions, whip spiders). Predatory terrestrial frogs and caecilians had lower 15N signatures than snakes, indicating that snakes are among the top predators in the terrestrial web. Based on the distribution of isotopic signatures, we estimated five trophic levels for both the aquatic and terrestrial food web. The food chains of a seasonal tropical site studied were rather short, which implies similarities to the structure of temperate food webs.
Fragebogen zur direkten Partizipation im Büro (FdP-B)
Authors: Lohmann Andrea , Prümper Jochen
Published: July 2006

Zusammenfassung. In diesem Beitrag wird der Fragebogen zur direkten Partizipation im Büro (FdP-B) vorgestellt. Er erfasst sowohl die subjektiv wahrgenommene, direkte Partizipation von MitarbeiterInnen als auch die damit in Zusammenhang stehenden Veränderungswünsche in 7 Bereichen der täglichen Büroarbeitsumwelt. Inhaltlich handelt es sich dabei um die Faktoren Arbeitsaufgabe, Arbeitsmittel, Arbeitsplatz, Arbeitsvertrag, Arbeitszeit, Personal- und Organisationsentwicklung. An einer Stichprobe von N = 1 354 MitarbeiterInnen aus zehn verschiedenen Branchen zeigten sich zufriedenstellende Reliabilitäts- und Itemkennwerte. Darüber hinaus konnten die für die Validierung angenommenen Zusammenhänge zwischen direkter Partizipation und Arbeitszufriedenheit, verschiedenen Belastungsfaktoren, Beanspruchung, Commitment, Führungsverhalten, Hilflosigkeit und dem Ausmaß von Kündigungsgedanken nachgewiesen werden. Auch in Hinblick auf das Involvement, die Art des Beschäftigungsverhältnisses, die Bildung, die Position im Unternehmen und die wöchentliche Arbeitszeit fanden die Hypothesen überwiegend Bestätigung. Damit steht für MitarbeiterInnenbefragungen ein solides Instrument zur Beschreibung der Partizipationskultur in Unternehmen zur Verfügung, mit dessen Ergebnissen konkrete Handlungsfelder für Verbesserungsmaßnahmen identifiziert werden können.
From the Subjects' Point of View
Authors: Kanning Uwe Peter , Grewe Kirsten , Hollenberg Stefan , Hadouch Monika
Published: July 2006

In personnel selection, situational judgment tests are based on the principle of simulation: The applicant is confronted with a typical work situation and has to decide what kind of behavior is appropriate. In two studies, we investigate the subjects' reactions to different kinds of situational judgment items. The item formats examined differ with regard to two variables: Interactivity (noninteractive: In each item, the subject is confronted with a new situation vs. interactive: The situation develops according to the answer given and the subject is asked once more about the new situation) as well as modality of presentation (stimulus and response components of the items are given in the form of a video vs. in text form). We expected the degree of interaction and the presentation via video to have a positive effect on the subjects' evaluation (in terms of usefulness, emotional reaction, transparency, job-relatedness, acceptance, fairness). In accordance with our expectations, interactive situational judgment items using videos in the stimulus as well as in the response component received the highest ratings.
Relativistic electron production during driven magnetic reconnection
Authors: Pritchett P. L.
Published: July 2006

Two‐ and three‐dimensional particle‐in‐cell simulations are used to determine the mechanism for producing relativistic electrons during externally driven magnetic reconnection in a plasma sheet configuration that models the near‐Earth growth phase magnetotail. The dominant process is found to be of the inverse Landau‐damping type in which those electrons with velocity component vx ≈ 0 at the X line are accelerated across the tail by the inductive reconnection electric field Ey. This process produces a power‐law energy spectrum for the electrons with a slope of ∼5–6, in agreement with recent observations.
Statistical characteristics and predictability of particle formation events at Mace Head
Authors: Yoon Y. J. , O'Dowd C. D. , Jennings S. G. , Lee S. H.
Published: July 2006

The seasonal characteristics of coastal nucleation events at the Mace Head Atmospheric Research Station, resulting from exposure of macroalgae to the atmosphere, were analyzed for a 2‐year period from August 2002 to July 2004. Nucleation events occurred on 58% of the days over the period. The seasonal variation of the number of event days and event duration show a clear cycle, with maximum values in spring and autumn and the minimum values in the winter season. The nucleation events typically start ∼75 min prior to the occurrence of the low‐tide mark and the event start time is correlated (r = 0.75) to the low‐tide height. The intensity of the events, as determined by the peak particle concentrations achieved, is also positively correlated with the amount of tidal areas exposed to ambient air, as determined by the tidal height, and solar radiation. A nucleation potential index (NPI) was developed as a tool to provide a predictive capability for event prediction at Mace Head. The index was derived from normalized tidal height, solar radiation intensity, and wind direction and was compared with the occurrence of nucleation events from the database. The result shows that Mace Head particle formation events can be quite well predicted with a threshold probability of 50%.
Experimental determination of transverse dispersivity in a helix and a cochlea
Authors: Benekos Ioannis D. , Cirpka Olaf A. , Kitanidis Peter K.
Published: July 2006

In porous media, transverse dispersion plays a decisive role in the dilution of conservative solutes, the decay of concentration fluctuations, and the mixing of reactive solutes. One possible approach for measuring the transverse dispersivity of homogeneous isotropic porous media is based on the principle of Taylor‐Aris dispersion, where the longitudinal macrodispersion coefficient is inversely proportional to the pore‐scale transverse dispersion coefficient. Taylor‐Aris dispersion requires a shear flow situation. To achieve the latter in porous media, we use a helix, as previously proposed, and also a cochlea, which is spiral‐shaped cavity resembling the interior a nautilus shell. We obtain experimental breakthrough curves from conservative tracer experiments and compare them to results of numerical simulation. By fitting the model we obtain the values of transverse dispersivity in various tracer tests. In our experiments we investigate porous media with relatively uniform particle distributions. Estimates of the transverse dispersivity are obtained for each experiment, and the relative advantages of each device are discussed. The two devices yield similar results. The estimated ratio of transverse dispersivity to longitudinal dispersivity agrees with the higher ratios reported in the literature.
Fast chemical and isotopic exchange of nitrogen during reaction with hot molybdenum
Authors: Yokochi Reika , Marty Bernard
Published: July 2006

Molybdenum crucibles are commonly used to extract nitrogen from geological samples by induction heating. Because nitrogen is known to be reactive with certain metals (e.g., Ti and Fe), we have tested the reactivity of gaseous nitrogen with a Mo crucible held at 1800°C. The consumption of nitrogen, determined by monitoring the N2/40Ar ratio of the gas phase, varied between 25 and 100%, depending on the reaction duration. Nitrogen of the reacted gas was found to be systematically enriched in 15N relative to 14N by 10‰ compared to the initial isotopic composition, without any correlation with nitrogen consumption. We propose that a rapid isotopic exchange occurs between nitrogen originally trapped in the crucible and nitrogen from the gas phase, which modifies the isotopic composition of the reacted gas. This process can significantly bias the isotopic determination of nitrogen in rocks and minerals when a Mo furnace is used for gas extraction. Meanwhile, the rate of N‐Mo chemical bonding may be controlled by the formation of nitride (rather than solid solution), a process slower than the isotopic exchange. The use of a Mo furnace for the extraction of trace nitrogen from rocks and minerals should therefore be avoided.
On the driving forces for protein-protein association
Authors: Ben-Naim Arieh
Published: July 2006

We analyze all the contributions to the standard free energy of association between two proteins. We find that the solvent-induced interactions between two (or more) hydrophilic groups can turn a highly unfavorable process of association into a highly favorable one. We therefore argue that in contrast to the generally accepted view, it is the hydrophilic rather than the hydrophobic effect that is dominant in biochemical processes such as protein-protein association, protein folding, and protein binding to DNA.
Nonlinear backward stimulated Raman scattering from electron beam acoustic modes in the kinetic regime
Authors: Yin L. , Daughton W. , Albright B. J. , Bowers K. J. , Montgomery D. S. , Kline J. L. , Fernández J. C. , Roper Q.
Published: July 2006

The backward stimulated Raman scattering (BSRS) of a laser from electron beam acoustic modes (BAM) in the presence of self-consistent non-Maxwellian velocity distributions is examined by linear theory and particle-in-cell (PIC) simulations in one and two dimensions (1D and 2D). The BAM evolve from Langmuir waves (LW) as electron trapping modifies the distribution to a non-Maxwellian form that exhibits a beam component. Linear dispersion relations using the nonlinearly modified distribution from simulations are solved for the electrostatic modes involved in the parametric coupling. Results from linear analysis agree well with electrostatic spectra from simulations. It is shown that the intersection of the Stokes root with BAM (instead of LW) determines the matching conditions for BSRS at a nonlinear stage. As the frequency of the unstable Stokes mode decreases with increasing wave number, the damping rate and the phase velocity of BAM decreases with the phase velocity of the Stokes mode, providing a self-consistently evolving plasma linear response that favors continuation of the nonlinear frequency shift. Coincident with the emergence of BAM is a rapid increase in BSRS reflectivity. The details of the wave-particle interaction region in the electron velocity distribution determine the growth/damping rate of these electrostatic modes and the nonlinear frequency shift; in modeling this behavior, the use of sufficiently large numbers of particles in the simulations is crucial. Both the reflectivity scaling with laser intensity and the spectral features from simulations are discussed and are consistent with recent Trident experiments.
Simple model of sickle hemogloblin
Authors: Shiryayev Andrey , Li Xiaofei , Gunton J. D.
Published: July 2006

A microscopic model is proposed for the interactions between sickle hemoglobin molecules based on information from the protein data bank. A solution of this model, however, requires accurate estimates of the interaction parameters which are currently unavailable. Therefore, as a first step toward a molecular understanding of the nucleation mechanisms in sickle hemoglobin, a Monte Carlo simulation of a simplified two patch model is carried out. A gradual transition from monomers to one dimensional chains is observed as one varies the density of molecules at fixed temperature, somewhat similar to the transition from monomers to polymer fibers in sickle hemoglobin molecules in solution. An observed competition between chain formation and crystallization for the model is also discussed. The results of the simulation of the equation of state are shown to be in excellent agreement with a theory for a model of globular proteins, for the case of two interacting sites.
Bispectral analysis of low- to high-confinement mode transitions in the National Spherical Torus Experiment
Authors: White A. E. , Zweben S. J. , Burin M. J. , Carter T. A. , Hahm T. S. , Krommes J. A. , Maqueda R. J.
Published: July 2006

This paper will present an experimental study of the temporal and spatial characteristics of the autobicoherence calculated from light amplitude fluctuations measured in the edge plasma of the National Spherical Torus Experiment (NSTX) [M. Ono et al., Plasma Phys. Controlled Fusion 45, A335 (2003)] using data from the gas puff imaging (GPI) diagnostic [R. J. Maqueda et al., Rev. Sci. Instrum. 74, 2020 (2003); S. J. Zweben et al., Nucl. Fusion 44, 134 (2004)] obtained during a series of thirteen shots in which the NSTX plasma underwent spontaneous low- to high-confinement mode (L-H) transitions. The autobicoherence calculated from the available GPI chord signals in the region near the magnetic separatrix and just above the outer midplane indicates that there is no significant increase, i.e., outside the rms error, in the amount of nonlinear coupling between low frequency fluctuations and high frequency fluctuations during the 10ms before the transition. Limitations of bicoherence analysis are discussed.
Quantum-state resolved reaction dynamics at the gas-liquid interface: Direct absorption detection of HF(v,J) product from F(P2)+Squalane
Authors: Zolot Alexander M. , Harper Warren W. , Perkins Bradford G. , Dagdigian Paul J. , Nesbitt David J.
Published: July 2006

Exothermic reactive scattering of F atoms at the gas-liquid interface of a liquid hydrocarbon (squalane) surface has been studied under single collision conditions by shot noise limited high-resolution infrared absorption on the nascent HF(v,J) product. The nascent HF(v,J) vibrational distributions are inverted, indicating insufficient time for complete vibrational energy transfer into the surface liquid. The HF(v=2,J) rotational distributions are well fit with a two temperature Boltzmann analysis, with a near room temperature component (TTD≈290K) and a second much hotter scattering component (THDS≈1040K). These data provide quantum state level support for microscopic branching in the atom abstraction dynamics corresponding to escape of nascent HF from the liquid surface on time scales both slow and fast with respect to rotational relaxation.
Near-infrared scintillation of xenon by Ni63 beta decay
Authors: Yoshimizu Norimasa , Lal Amit , Pollock Clifford R.
Published: July 2006

The near-infrared scintillation of xenon gas by the β decay of 37MBq of Ni63 was studied, in the interest of its use in integrated devices for applications such as optical beacons and wavelength calibration. The emission was imaged and analyzed using Spencer’s theory of electron penetration using xenon scattering cross sections derived from Thomas-Fermi theory. The total emission was approximately 2×105photons∕s at 20kPa and 1×105photons∕s at 100kPa. Spectral data show three dominant peaks at 823, 828, and 882nm as well as the formation of metastable states.
Radiative recombination and ultralong exciton photoluminescence lifetime in GaN freestanding film via two-photon excitation
Authors: Zhong Yongchun , Wong Kam Sing , Zhang Weili , Look D. C.
Published: July 2006

We have measured the photoluminescence (PL) lifetime of a freestanding GaN film using one-photon and two-photon excitations to demonstrate the dramatic difference in exciton recombination dynamics at the surface and in the bulk. An ultralong exciton PL lifetime of 17.2ns at 295K is observed from a GaN freestanding film using two-photon excitation, whereas less than 100ps lifetime is observed for one-photon excitation, suggesting that nonradiative processes from surface defects account for the short PL lifetime measured. A monotonic increase in two-photon excited PL lifetime with increasing temperature and the linear dependence of the exciton lifetime with emission wavelength show good agreement with the theoretical predictions, indicating that radiative recombination dominates for bulk excited state relaxation processes.
Giant magnetoresistance in an all-oxide spacerless junction
Authors: Singh M. P. , Carvello B. , Ranno L.
Published: July 2006

We report the fabrication of an oxide-specific type of magnetoresistive junction, which is a ferromagnetic bilayer. Both electrodes are high spin-polarization oxides: magnetite (Fe3O4) and manganite (La0.7Sr0.3MnO3). Negligible magnetic coupling between both ferromagnetic electrodes is realized, which allows us to obtain parallel and antiparallel magnetic configurations of the electrodes when sweeping the applied magnetic field. The structure exhibits negative giant magnetoresistance (GMR) at low temperatures. This negative MR shows that both electrodes stay spin polarized at the interface and have opposite spin polarizations, i.e., the Fe3O4 layer has a negative spin polarization at low temperature. Maximum GMR (−5%) is obtained at 55K.
Millimeter wave analysis of the dielectric properties of oil shales
Authors: Scales John A. , Batzle Michael
Published: July 2006

Natural sedimentation processes give rise to fine layers in shales. If these layers alternate between organic-rich and organic-poor sediments, then the contrast in dielectric properties gives rise to an effective birefringence as the presence of hydrocarbons suppresses the dielectric constant of the host rock. We have measured these effects with a quasioptical millimeter wave setup that is rapid and noncontacting. We find that the strength of this birefringence and the overall dielectric permittivity provide two useful diagnostics of the organic content of oil shales.
Analysis of the charge transport in π-conjugated materials using generalized Langevin equation
Authors: Kim Seong Hyun , Lim Sang Chul , Lee Jung Hun , Ku Chan Hoi , Koo Jae Bon , Yang Yong Suk , Zyung Taehyoung
Published: July 2006

The complex dielectric constants of several π-conjugated materials are measured, and generalized Langevin equation is used to analyze the dielectric behavior in the frequency domain. From the results of a fitting of the experimental data, all of the dielectric behaviors are well interpreted by the generalized Langevin equation which strongly suggests that the mechanism of the charge carrier transport in π-conjugated organic and polymeric materials is diffusion at dc and low frequencies and an oscillatory motion at (or near) phonon frequencies, and in between, a mixed mode of these two mechanisms.
Polarization-independent and submillisecond response phase modulators using a 90° twisted dual-frequency liquid crystal
Authors: Huang Yuhua , Wen Chien-Hui , Wu Shin-Tson
Published: July 2006

A polarization-independent phase modulator using a 90° twisted dual-frequency liquid crystal (DFLC) is demonstrated. In addition to being polarization independent, such a phase modulator exhibits many other advantages such as being scattering-free and having large phase change, low operating voltage, and submillisecond response time. Using a 15μm transmissive DFLC cell, the phase shift achieves 1π at λ=633nm and the applied voltage is lower than 25Vrms. Potential applications of such a phase modulator for laser beam steering, tunable-focus lenses, and switchable two-dimensional/three-dimensional liquid crystal displays are foreseeable.
Effect of electron detachment on the wall potential and plasma evolution in the afterglow stage
Authors: Bogdanov E. A. , DeJoseph C. A. , Demidov V. I. , Kudryavtsev A. A.
Published: July 2006

It is demonstrated that detachment of electrons in the afterglow of an electronegative plasma can lead to a significant increase in negative wall potential with respect to the plasma potential. This effect can be used to modify the near-wall sheath electric field and thickness, which are important for plasma processing applications. Also in the afterglow, this effect can lead to an increase in electron density with time, and a reduction (up to total exclusion) in diffusion cooling of electrons and can thus be used to modify the electron temperature.
Nanoscale carrier transport in Ti∕Al∕Ni∕Au Ohmic contacts on AlGaN epilayers grown on Si(111)
Authors: Roccaforte F. , Iucolano F. , Giannazzo F. , Alberti A. , Raineri V.
Published: July 2006

In this letter, a correlation between nanostructure and current flow in Ti∕Al∕Ni∕Au Ohmic contacts on AlGaN films grown on Si(111) is reported. A cross correlation between conductive-atomic force microscopy and structural analyses (x-ray diffraction, transmission electron microscopy) demonstrates that the structure and the electrical properties of the different phases formed inside the reacted layer upon annealing are crucial for the nanoscale current transport. The experimental measurement of the resistivity of the main phases formed upon annealing (AlNi, AlAu4, and Al2Au) indicated that the low resistivity Al2Au phase provides preferential conductive paths for the current flow through the contact.
Photoluminescence study of InSb∕AlxIn1−xSb quantum wells
Authors: Zhang X. H. , Doezema R. E. , Goel N. , Chung S. J. , Santos M. B. , Dai N. , Zhao F. H. , Shi Z. S.
Published: July 2006

We present the results of photoluminescence experiments on InSb∕AlxIn1−xSb multi-quantum-wells on GaAs substrates. A comparison of the photoluminescence signals with transmission measurements shows Stokes shifts of 2.8–6.9meV, indicating that the low temperature luminescence is mainly due to bound excitons localized by interfacial potential minima. The high temperature signal is attributed to ionized free carriers. The well width dependent thermal activation energy investigation indicates that nonradiative carrier loss from the wells to the barriers is not a dominant mechanism. Instead, we suggest that the thermal recombination by surface dislocations or defects might be the main nonradiative channel for high temperature luminescence.
Visualization of the complex refractive index of a conductor by frustrated total internal reflection
Authors: Bliokh Yu. P. , Vander R. , Lipson S. G. , Felsteiner J.
Published: July 2006

A simple imaging geometry in which total internal reflection in a glass prism is frustrated by the proximity of a metal surface is implemented for observation of surface plasmon resonance. At a certain angle of incidence, the total internal reflection is completely suppressed at a certain distance between the metal and the prism surfaces. Using planar metal and spherical prism surfaces, the distance parameter is sampled in a single image. This allows a direct determination of the complex refractive index in bulk samples as well as in thin films. Our experimental data are in good agreement with previously published data.
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FePt films deposited on pyramid-type Si substrate for perpendicular magnetic recording media
Authors: Zha C. L. , Ma B. , Zhang Z. Z. , Gao T. R. , Gan F. X. , Jin Q. Y.
Published: July 2006

Tetragonal L10 FePt films are deposited on the pyramid-type Si substrates fabricated by chemical etching process from (100) Si wafers. The films are composed of different easy-axis orientation FePt grains, most of which with the easy axis along substrate normal, the others with the easy axis tilted from the normal direction. When the magnetic field is applied along the perpendicular direction, the easy-axis tilted grains reverse first, and then the magnetization reversal of the whole film is promoted. Small coercivity, suitable α, and high squareness are obtained. And the coercivity increases when the applied field is tilted from the normal direction.