bluuebunny/crossref_metadata_2025 huggingface dataset:
The elusiveness of spiritual wisdom in the art and science of nursing practice
Authors: Moreau Jeannine
Published: February 2008

As two students and a teacher immersed in practice education at a Canadian nursing school. We were curious about how to engage in spiritual health care practice, viewed as relational nursing practice that assumes interconnections of spirit, health and healing. This paper explores how to interpret theoretical understandings into pragmatics of teaching, learning and engaging in spiritual health care practice. There is discussion about story telling, taking a stand of ‘not knowing’ (Irving and Moffatt, 2002), opening space for diversity, authentic dialogue across, within and through difference to inform pragmatic ways of knowing, being and of doing spiritual health care. To inform the discussion, theoretical perspectives on the religion/spirituality divide, interconnections of health, healing and spirit, ‘defining moments’ and spiritual/sacred spaces are presented. A review of the literature juxtaposed with student/teacher experiences and perspectives helps to inform a deeper understanding of teaching, learning and engaging in spiritual health care practice. Copyright © 2008 John Wiley & Sons, Ltd.
Investigation of oxidation of a U‐2.5 wt% Nb alloy in air at low temperatures: kinetic study and oxide characterization
Authors: Jiangrong Yang , Xiaolin Wang , Lizhu Luo , Ping Zhou
Published: February 2008

Alloying uranium with niobium can greatly enhance the corrosion resistance of metallic uranium. In the present article, the oxidation behavior of a U‐2.5 wt% Nb alloy in air over the temperature range 333 to 573 K was investigated. XPS technique was employed to characterize the oxide products. The results of oxidation‐rate curves show that at temperatures below 353 K the oxidation of U‐2.5 wt% Nb alloy follows a parabolic‐rate law, and in the temperature range of 373–423 K paralinear rate laws seem to apply, however, above 473 K linear laws are observed. The oxidation‐rate dependence of temperature is obtained, and the activation energies for different oxidation stages are determined. The XPS analysis indicates that under experimental conditions the predominant oxide formed on the outer surface is stoichiometric UO2.0 intermixed with Nb2O5, and below the outmost thin layer, an inner oxide layer consisting of UO2, NbO is presented. Copyright © 2008 John Wiley & Sons, Ltd.
Investigation of Mn‐dimers formation in silicon by SIMS method
Authors: Saraykin Vladimir , Trifonov Alexey
Published: February 2008

It has been theoretically predicted that manganese atoms in silicon matrix tend to form dimers which can show both ferro‐ and antiferromagnetic properties. One might expect that the significant part of such dimers (N‐mers) should be spattered as cluster ions while SIMS measurement. We have investigated samples of silicon wafers implanted with manganese ions and annealed. In the solid solution the probability of the situation when N doped atoms are nearest neighbours is proportional to Nth power of concentration. However, if in the solution the process of enhancement of neighbouring impurity atoms number takes place, the cluster ion signal should exceed the power law. We have verified the validity of this statement in ion implanted solutions of B and Mn in silicon. SIMS measurements in annealed samples show that the profile of Mn2 and Mn3 ions essentially exceed respectively the square and the cube of manganese concentration. Quantitative estimation shows that in the annealed sample at some depths manganese dimers contain about 10% of total Mn atoms. The connection between the obtained profiles and magnetic measurements is discussed. Copyright © 2008 John Wiley & Sons, Ltd.
Designing systems for adaptability by means of architecture options
Authors: Engel Avner , Browning Tyson R.
Published: February 2008

The value of a system usually diminishes over its lifetime, but some systems depreciate more slowly than others. Diminished value is due partly to the increasing needs and wants of the system's stakeholders and partly to its decreasing capabilities relative to emerging alternatives. Thus, systems are replaced or upgraded at substantial cost and disruption. If a system is designed to be changed and upgraded easily, however, this adaptability may increase its lifetime value. How can adaptability be designed into a system so that it will provide increased value over its lifetime? This paper describes the problem and an approach to its mitigation, adopting the concept of real options from the field of economics, extending it to the field of systems architecture, and coining the termarchitecture optionsfor this next‐generation method and the associated tools fordesign for adaptability. Architecture options provide a quantitative means of optimizing a system architecture to maximize its lifetime value. This paper provides two quantitative models to assess the value of architecture adaptability. First, we define three metrics—component adaptability factors, component option values, andinterface cost factors—which are used in a static model to evaluate architecture adaptability during the design of new systems. Second, we enhance a dynamic model to evaluate architecture adaptability over the maintenance and upgrade lifetime of a system, formulating aDesign for Dynamic Value(DDV) optimization model. We illustrate both models with quantitative examples and also discuss how to obtain the socio‐economic data required for each model. © 2008 Wiley Periodicals, Inc. Syst Eng
Speed adaptive mobile IP over wireless LAN
Authors: Tian Jun , Helal Abdelsalam (Sumi)
Published: February 2008

In this paper, the performance of MIP/WLAN at different moving speeds is evaluated on a testbed. The result shows that current MIP protocol is not suitable for rapid moving environments. Through analyzing the relationship of the performance and the moving speed and breaking down the handoff latency of MIP over WLAN, we propose a speed adaptive MIP protocol extension. In this protocol extension, a concept, handoff rate, is defined and is used to extend the MIP protocol. An evaluation of the speed adaptive MIP shows that it greatly improves the performance of MIP over WLAN in rapid moving environments. Copyright © 2008 John Wiley & Sons, Ltd.
A future location‐aware replacement policy for the cache management at the mobile terminal
Authors: Drakatos Stylianos , Pissinou Niki , Makki Kia , Douligeris Christos
Published: February 2008

While the traditional data shipping systems use physical information to organize data, a newer data caching technique maintains both associated answers (data items) of previous queries and their meaning (purpose). This form of information description is called semantic description, and it makes it possible to reason about and derive knowledge from the given description. In a distributed heterogeneous environment, such as the mobile environment, the semantic data caching paradigm is an important technique for improving the performance of wireless data dissemination systems. Data caching performance depends heavily on the replacement policy being used for the cache management. However, future location uncertainty, limited client resources and frequent client disconnections make cache management a challenge.

This paper proposes a future location‐aware cache replacement policy to manage a semantic cache. The proposed replacement policy uses the validity of the data fetched from the server and the neighboring locations to decide which of the cache entries is less likely to be needed in the future, and therefore a good victim for eviction when cache space is needed. The replacement policy's preference for cached items to be evicted is modeled as a general function that declines with distance between the mobile user's current location and the candidate for replacement cached item's bound location. For better efficiency, the overall replacement granularity is dynamically achieved along three levels: ring, cell and data item. Simulation study of the proposed approach shows that it outperforms both the least recently used (LRU) and furthest away replacement (FAR) schemes, where only temporal locality is considered. Moreover, the proposed scheme is easier to implement than other research and development proposals. Copyright © 2008 John Wiley & Sons, Ltd.
PIXE and ionoluminescence for Mesoamerican jadeite characterization
Authors: Ruvalcaba‐Sil J. L. , Manzanilla L. , Melgar E. , Lozano Santa Cruz R.
Published: February 2008

Greenstones were highly appreciated in pre‐Hispanic Mesoamerica. Most of the finest green artifacts were worked in jadeite and other minerals such as serpentine and nephrite. Jadeite, the most precious stone in ancient Mesoamerica, was widely used and traded since the Preclassic Horizon (1500 B.C.). The main beds are located in the Maya region, in the Motagua area of Guatemala. In this work, three pieces of a necklace of greenstones from an offering (corresponding around 155 A.D.) discovered in an extensive excavation carried out in the palatial structure of Xalla, at Teotihuacan site, in the central highlands of Mexico, were studied using external beam particle induced x‐ray emission (PIXE). The necklace is composed by 11 round pieces of green colors ranging from light to dark green. The aim of this study is to determine the elemental composition of the greenstones and to establish the sourcing, trade and relationship between these regions. Thus, several jadeite samples from Manzanal sources of Motagua were analyzed as well. The elemental composition comparison between the archaeological items and the known jadeite samples indicates that only one archaeological piece is related to the Manzanal sample source. Green luminescence of high intensity was observed for the archaeological pieces but only in one case the luminescence was blue–violet. When comparing with green stone mineral samples, only jadeite presented luminescence. The spectra, corresponding mainly to Mn2+, Ce3+ and Al3+ emissions, were collected under proton induced luminescence in vacuum on the jadeite samples. No correlation was observed among light emission color and jadeite sources. Copyright © 2008 John Wiley & Sons, Ltd.
DT2, a PIXE spectra simulation and fitting package
Authors: Reis M. A. , Chaves P. C. , Alves L. C. , Barradas N. P.
Published: February 2008

Recently, a new PIXE code, LibCPIXE, was produced as a variant to the old DATTPIXE package following a simulation‐based approach usually not used in PIXE data handling. This approach required to merge the PIXE data handling code, LibCPIXE to NDF, a well‐known code for handling RBS and other IBA methods data, and showed that complex structures in the samples can dramatically change the observed PIXE yields. A full stepwise process was then undertaken in order to produce a new PIXE data handling code that uses the simulation approach not only to estimate the number of K‐α and L‐α x‐rays emitted by the elements present in structured samples but to fit the entire PIXE energy spectra. This approach is of particular importance for the new high x‐ray energy and high resolution PIXE set‐up being installed at ITN, for the precise interpretation of PIXE spectra from complex targets, and also as a robust basis to relative yield ion energy dependence (RYIED) work discussed elsewhere in this conference. In this communication we present the fitting core for the new DT2 package and discuss its capacity. Copyright © 2008 John Wiley & Sons, Ltd.
Particle size/composition relationships of wind‐eroding sediments, Owens (dry) Lake, California, USA
Authors: Rojo Lila , Gill Thomas E. , Gillette Dale A.
Published: February 2008

Major, minor, and trace element concentrations were determined by particle‐induced x‐ray emission (PIXE) in 118 aeolian sediment samples collected at six heights in seven locations along a 1.2 km transect during three sequential dust storms at Owens (dry) Lake, California, USA. Na and S concentrations covaried with each other (and inversely with Si and Ca), increased with height, and decreased with distance downwind and time. Mg, Al, Si, K, Mn, Fe, and Sr concentrations at northerly sites varied with height and location as opposed to nearly constant concentrations at southerly locations. Volumetric particle‐size distribution (PSD) for each sample was determined via laser diffraction. PSDs of the collected sediment reflected a trimodal distribution:63% of samples peaked at 20–50 µm (silt), 11% at 50–100 µm (very fine sand) and 26% at 100–250 µm (fine sand). Most silty samples occurred during the first two events. Significant differences in element concentrations existed in relation to the PSDs. Na and S concentrations were proportional to the submicron to silt particle fraction during each event. Al, Ti, Mn, K, Fe, and Rb concentrations correlated with 100–500 µm (fine/medium sand) particles in the first two events and a wider PSD range 250–1000 µm (coarse sand) in the third event. The results suggest sodium sulfate aerosol emission during the first windstorm, while subsequent saltation‐dominated events released more aluminosilicate minerals containing higher trace metal concentrations. These combined techniques reveal particle size/chemical fractionation and spatial variability of sediment properties during resuspension at aeolian ‘hotspots,’ with implications to geochemical cycling and aerosol source/receptor relationships. Copyright © 2008 John Wiley & Sons, Ltd.
Silicon detector dead layer thickness estimates using proton bremsstrahlung from low atomic number targets
Authors: Cohen David D. , Stelcer Eduard , Siegele Rainer , Ionescu Mihail
Published: February 2008

Proton‐induced bremsstrahlung radiation in the 1–5 keV energy range has been used to estimate the silicon dead layer thickness in a Si(Li) detector. This novel technique does not require accurate bremsstrahlung cross sections with x‐ray energy; it just assumes these cross sections and hence the efficiency corrected yield is both smooth and continuous across the Si K edge at 1.838 keV. Copyright © 2008 John Wiley & Sons, Ltd.
Localisation of trace metals in metal‐accumulating plants using µ‐PIXE
Authors: Siegele R. , Kachenko A. G. , Bhatia N. P. , Wang Y. D. , Ionescu M. , Singh B. , Baker A. J. M. , Cohen D. D.
Published: February 2008

Particle induced x‐ray emission (PIXE) is a very sensitive technique that can quickly and reliably measure a wide range of elements simultaneously with high sensitivity. Using a focused microbeam, elemental distributions can be mapped with high spatial resolution. We demonstrate high‐resolution mapping of metals in plant leaves at 5 µm resolution and its application in detecting sites of metal accumulation in metal‐accumulating plant tissues. The importance of biological sample preparation is discussed by direct comparison of freeze‐substitution and freeze‐drying techniques routinely used in biological sciences. The advantages and limitations of quantitative elemental imaging using these techniques are also discussed. Copyright © 2008 John Wiley & Sons, Ltd.
Microbeam analysis of yellow sand dust particles
Authors: Matsuyama S. , Ishii K. , Yamazaki H. , Kikuchi Y. , Kawamura Y. , Oyama R. , Yamanaka K. , Yamamoto T. , Watanabe M. , Tsuboi S. , Arao K.
Published: February 2008

A microbeam system was applied to analyses of yellow sand dust particles. Such particles from the Asian continent sometimes cause turbid conditions in Japan, especially in spring, and are sometimes changed by mixing with anthropogenic and marine aerosols. For better understanding of their formation mechanism, analysis of single particles is indispensable. For this purpose, we developed a microbeam analysis system at Tohoku University with a spatial resolution of better than 1 µm. The system comprises two x‐ray Si(Li) detectors for particle‐induced x‐ray emission (PIXE), an annular ion‐implanted Si detector for Rutherford backscattering (RBS), an ion‐implanted Si detector for off‐axis scanning transmission ion microscopy (STIM), and a Si‐PIN photodiode for direct STIM analyses. The combination of PIXE, RBS and off‐axis STIM methods enabled simultaneous analyses of hydrogen to metal elements and revealed the chemical compositions of these particles. Yellow sand dust particles were impacted on a thin polycarbonate film and analyzed using the microbeam analysis system. After quantification of the elemental components of these particles, the chemical composition of each particle was obtained. Silicon, calcium, oxygen, carbon, and hydrogen are the main composing elements of the particles originating mainly from soil dust from the Asian continent. The particles contain sulfur and heavier elements too, originating from mixing with anthropogenic aerosols. Sodium, magnesium, and chlorine, which come from marine aerosols, are also included in these particles and might be adsorbed during transport from the Asian continent. Single particle analysis of yellow sand dust will engender a better understanding of their formation process during transport. Copyright © 2008 John Wiley & Sons, Ltd.
Benefits of combined PIXE and AMS with new accelerators
Authors: Demortier Guy , Quarta Gianluca , Butalag Karim , D'Elia Marisa , Calcagnile Lucio
Published: February 2008

Combination of the elemental nondestructive analysis of artifacts by ion beam analysis (IBA) multielemental techniques (but mostly PIXE) with the accelerator mass spectroscopy (AMS) measurement of the age of the organic material discovered in the close vicinity of these artifacts (mainly available for recent excavations) gives new tools to archaeologists to improve their diagnosis in the study of the composition of ancient objects and of their workmanship in ancient times by using the same experimental facility for IBA and AMS. For potteries and metallic samples, IBA and AMS are to be applied on different samples excavated in the same environment but for organic archaeological samples, IBA and AMS techniques could be sequentially used on the same material. Results of these combined techniques on artifacts of various origins recently studied at CEDAD (CEntro di Datatione e Diagnostica), University of Salento, Lecce, Italy, are presented. Copyright © 2008 John Wiley & Sons, Ltd.
Empirical approximation for Lα production cross sections
Authors: Šmit Ž , Tancek A.
Published: February 2008

The production cross sections for Lα x‐ray lines of the elements Z = 47–92 induced with protons up to 4‐MeV energy are given by a simple empirical expression suitable for thick‐target particle induced x‐ray emission (PIXE) applications. The logarithm of Lα1, 2 production cross section is expressed as an eight‐parameter rational function of the logarithm of the proton energy. The parameters were obtained by fitting the function to the tabulated data of Reis and Jesus (Atomic Data and Nuclear Data Tables 1995; 63). The accuracy of the fit is within several percent in the high‐energy region, about 5% in the vicinity of the discontinuous jumps of the tabulated data, and about 10–20% in the low‐energy region below 200 keV. Copyright © 2008 John Wiley & Sons, Ltd.
Chemical composition and mass closure for PM2.5 and PM10 aerosols at K‐puszta, Hungary, in summer 2006
Authors: Maenhaut Willy , Raes Nico , Chi Xuguang , Cafmeyer Jan , Wang Wan
Published: February 2008

A comprehensive chemical aerosol characterisation was carried out at K‐puszta, Hungary, from 24 May until 29 June 2006. Up to 11 June it was unusually cold at the site, but from 12 June onwards it was warm. PM2.5 and PM10 samplers with Nuclepore polycarbonate filters and quartz fibre filters were deployed in parallel for mostly day and night collections. All samples were analysed for the particulate mass (PM) by weighing. The Nuclepore polycarbonate filters were analysed for up to 29 elements by particle‐induced x‐ray emission spectrometry (PIXE) and for major anions and cations by ion chromatography. The quartz fibre filters were analysed for organic and elemental carbon by a thermal‐optical transmission technique. The atmospheric concentrations of the PM and most species and elements were higher during the warm period than during the cold one. Aerosol chemical mass closure calculations were done for the PM2.5 and PM10 aerosols. As gravimetric PM data we used the data from the Nuclepore polycarbonate filters. For reconstituting this PM, eight aerosol components were considered. Organic matter contributed by far the most to the PM2.5 and PM10 PM; it was responsible for 40–50% of the average PM. Noteworthy were the much larger percentages of crustal matter during the warm period than during the cold one. In the PM2.5 aerosol, crustal matter accounted for 17% of the average PM during the warm period, but only for 3.1% during the cold period. For the PM10 aerosol, the percentages were 28% in the warm period and 10% in the cold one. Copyright © 2008 John Wiley & Sons, Ltd.
Two Different Surgical Approaches in the Treatment of Adenocarcinoma at the Gastroesophageal Junction
Authors: Johansson Jan , Djerf Pauline , Öberg Stefan , Zilling Thomas , von Holstein Christer Staël , Johnsson Folke , Walther Bruno
Published: February 2008

Background

Adenocarcinoma at the gastroesophageal junction may be regarded as of esophageal or of gastric origin, and tumor removal may follow the principles of esophagectomy or extended gastrectomy. We determined the impact of this strategy on our patients with tumors at this site.

Methods

Baseline patient and tumor characteristics were collected, and tumors were categorized according to Siewert’s classification (I, II, or III) of gastroesophageal junction tumors. Totally, 133 patients were operated on between 1990 and 2001. Ninety‐six patients with type I (n = 67), II (n = 26), and III (n = 3) tumors underwent esophagectomy and gastric tube reconstruction, and 37 patients with type I (n = 5), II (n = 26), and III (n = 6) tumors underwent extended gastrectomy and long Roux‐en‐Y reconstructions.

Results

After adjusting for the independently significant impact factors—tumor stage, tumor dissection (R0–R2), and length of tumor free resection margins—we did not find any specific survival benefit associated with either of the two evaluated surgical approaches for tumor resection and reconstruction. The EORTC quality of life forms revealed good results as indicated by the functional scales and the symptom scales.

Conclusions

Provided that adequate tumor dissection is performed, patients with adenocarcinoma at the gastroesophageal junction can be resected and reconstructed using the principles for esophagectomy or extended gastrectomy.
Public Health Asks of Community Psychology…
Authors: Green Lawrence W.
Published: February 2008

As the field of public health has increasingly recognized the social and behavioral aspects of the changing epidemiology of diseases and injuries, it has added social and behavioral scientists to the faculties of schools of public health and most federal and state public health agencies. Community psychology can play a crucial role in helping to bridge the dominant psychological theories with the family and community contexts in which individuals are conditioned and reinforced in their tendencies toward violent behavior. Public health asks of community psychology a helping hand in bridging the clinical endpoints of most NIH‐sponsored behavioral research with the community endpoints of most CDC‐sponsored programs such as injury control.
Assembly of Silver Nanoparticles into Hollow Spheres Using Eu(III) Compound based on Trifluorothenoyl-Acetone
Authors: Sun Youyi , Liu Yaqing , Zhao Guizhe , Zhang Qijin
Published: February 2008

The preparation of luminescent silver hollow spheres using Eu(III) compound based on trifluorothenoyl-acetone is described. The structure and size of silver hollow spheres were determined by TEM images. The result shows the formation of hollow structure and average size of the silver hollow spheres (0.9 μm). The silver hollow spheres were further characterized by UV absorption spectrum, SNOM and SEM images, suggesting them to be formed by self-assemble of some isolated silver nanoparticles. The luminescent properties of them were also investigated and they are shown to be high emission strength; moreover, they offer the distinct advantage of a lower packing density compared with other commercial luminescent products.
Analysis of Minor Products in Linear Alkylbenzene Sulfonation. Comparison Between the Traditional Gravimetric Method and High Performance Liquid Chromatography (HPLC) Procedures Versus High Temperature Gas Chromatography (HT‐GC)
Authors: Bengoechea C. , Fernández A.
Published: February 2008

During the sulfonation process of the linear alkylbenzene (LAB) other products like sulfones and anhydrides are also formed in addition to the linear alkylbenzene sulfonic acid (HLAS). Most of them are transformed in different degrees during the aging and hydrolysis steps of the overall sulfonation process [Moreno et al. (2003) J Surfactant Deterg 6(2):137–142]. The use of HPLC technique since 1988 and earlier the use of high temperature gas chromatography (HT‐GC) enable the separation and quantification of all the components of the free oil (FO) of the sulfonic acids—anhydrides; LAB and sulfones. The purpose of this paper is to review the current knowledge about the free oil analysis and to discuss a new analytical procedure based on the HT‐GC to quantify the free oil content. We will compare the results obtained using this new method with other analytical procedures (traditional gravimetry) and near infrared (NIR) spectroscopy.
Primary Hydroxyl Content of Soybean Polyols
Authors: Ionescu Mihail , Petrović Zoran S. , Wan Xianmei
Published: February 2008

Polyurethanes are obtained by reacting polyols with polyisocyanates. The primary hydroxyl content is a very important characteristic of polyols because it affects their reactivity. Typically primary hydroxyls are approximately threefold more reactive than the secondary hydroxyls when reacting with aromatic isocyanates. This paper presents a simple and convenient kinetic method for determining the primary hydroxyl content in soybean polyols, based on the difference in reactivity of primary and secondary hydroxyls with phenyl isocyanate (PI). The reaction kinetics were studied by following the disappearance of the NCO band at 2260 cm−1 with time in the infrared spectra. The reaction of PI with soybean polyols was carried out in a toluene:dimethylformamide (9:1, v/v) mixture. The relative error of the method is in the range of ±5%. The method is characterized by simplicity and good reproducibility, and it can be applied to all soybean polyols irrespective of their structure.
Transthyretin binding to A‐Beta peptide – Impact on A‐Beta fibrillogenesis and toxicity
Authors: Costa R. , Gonçalves A. , Saraiva M.J. , Cardoso I.
Published: February 2008

It has been suggested that transthyretin (TTR) is involved in preventing A‐Beta fibrillization in Alzheimer's disease (AD). Here, we characterized the TTR/A‐Beta interaction by competition binding assays. TTR binds to different A‐Beta peptide species: soluble (Kd, 28 nM), oligomers and fibrils; diverse TTR variants bind differentially to A‐Beta. Transmission electron microscopy (TEM) analysis demonstrated that TTR is capable of interfering with A‐Beta fibrillization by both inhibiting and disrupting fibril formation. Co‐incubation of the two molecules resulted in the abolishment of A‐Beta toxicity. Our results confirmed TTR as an A‐Beta ligand and indicated the inhibition/disruption of A‐Beta fibrils as a possible mechanism underlying the protective role of TTR in AD.
A NOTE ON A RESULT OF RUZSA
Authors: TANG MIN
Published: February 2008

Let σA(n)=∣{(a,a′)∈A2:a+a′=n}∣, where $n\in \mathbb {N}$ and A is a subset of $\mathbb {N}$. Erdös and Turán conjectured that, for any basis A of $\mathbb {N}$, σA(n) is unbounded. In 1990, Ruzsa constructed a basis $A\subset \mathbb {N}$ for which σA(n) is bounded in the square mean. In this paper, based on Ruzsa’s method, we show that there exists a basis A of $\mathbb {N}$ satisfying $\sum _{n\leq N}\sigma _A(n)^2\leq 1\,449\,757\,928N$ for large enough N.
COMPACT DIFFERENCES OF COMPOSITION OPERATORS
Authors: WOLF ELKE
Published: February 2008

Let ϕ andψbe analytic self-maps of the open unit disk. Each of them induces a composition operator,CϕandCψrespectively, acting between weighted Bergman spaces of infinite order. We show that the differenceCϕ−Cψis compact if and only if both operators are compact or both operators are not compact and the pseudohyperbolic distance of the functions ϕ andψtends to zero if ∣ϕ(z)∣→1 or ∣ψ(z)∣→1.
Effects of moderate hyperhomocysteinaemia induced by 4 weeks methionine-enriched diet on metabolite profile and mesenteric artery function in rats
Authors: Pexa Annette , Boeger Rainer H. , Henle Thomas , Schwedhelm Edzard , Deussen Andreas
Published: February 2008

Methionine is an essential amino acid and methyl donor for most transmethylation reactions in mammals. The product of transmethylation reactions is homocysteine, which is associated with enhanced risk for CVD. The aim of this study was to analyse metabolic and vascular functional consequences of a methionine-enriched diet in rats. The dose of methionine was chosen to reflect the range of over-nutrition in man. We quantified plasma levels of homocysteine, asymmetrical dimethylarginine and adenosine, determined methionine and its metabolites in tissues and blood plasma and assessed relaxation of mesenteric arteries toward acetylcholine and sodium nitroprusside. A methionine-enriched diet for 4 weeks elevated homocysteine levels in plasma 2-fold and in spleen by 70 %. The level ofS-adenosylhomocysteine was increased in liver only, while methionine andS-adenosylmethionine were unchanged in all organs studied. Plasma adenosine and asymmetrical dimethylarginine levels were unchanged, as were vessel relaxations. A 2-fold elevation of plasma homocysteine, which is assigned a risk indicator for cardiovascular events, did not impair mesenteric artery vasodilatation during 4 weeks of a methionine-rich diet. Furthermore, asymmetrical dimethylarginine and adenosine, which have been shown to be changed in more severe degrees of hyperhomocysteinaemia, remained unaltered.
Olfactory conditioning in mate searching by the parasitoidAphidius ervi(Hymenoptera: Braconidae)
Authors: Villagra C.A. , Vásquez R.A. , Niemeyer H.M.
Published: February 2008

Despite the fact that insect learning capacity has been broadly demonstrated, the role that this process plays during mate searching has been scarcely explored. We studied whether the sexual behaviour of a male parasitic wasp can be conditioned to the odours from two alternative host plant complexes (HPCs) present during its first copulation. The experimental subjects were newly emerged males of the aphid parasitoid,Aphidius ervi, and two alternative HPCs (alfalfa or wheat). In the training protocol, copulation experience corresponded to an unconditioning stimulus and HPC odours to the conditioning stimuli. The initial (just after eclosion) and trained responses were assessed in a glass Y-olfactometer. The results showed that neither alfalfa HPC nor wheat HPC stimuli elicited sexual-related behaviours in initial male responses. Conversely, both HPCs triggered strong attraction and wing fanning courtship behaviour in trained responses when the male was exposed to a female plus HPC during training. In males trained with females plus a given HPC but tested with the alternative HPC in the olfactometer, trained response showed a similar trend to the non-associative treatments. Hence, through learning, the olfactory stimulus context present during copulation could become a predictive cue for further mate searching. These results are discussed in terms of parasitic wasp ecology and host fidelity.
Native parasitoids and their potential to control the invasive leafminer,Cameraria ohridellaDESCH. & DIM. (Lep.: Gracillariidae)
Authors: Klug T. , Meyhöfer R. , Kreye M. , Hommes M.
Published: February 2008

In spite of the fact that since the end of the eighties, the horse chestnut leafminer,Cameraria ohridella, has established itself throughout Europe, native predators such as ants and birds are not attuned to this neozoic species. In contrast, several parasitic wasp species already started to exploit the invasive horse chestnut leafminer, but until now parasitation rates are quite low, mainly because of asynchrony in the lifecycles of parasitoids and host. Only the removal of leaf litter, in which pupae hibernate, is at the moment a strategy to reduce the infestation level in the next year. Unfortunately, not only hibernating horse chestnut leafminers but also parasitoids are removed, and important resources for biocontrol are unused. In the current study, we investigated the potential efficiency of the horse chestnut leafminer parasitoid complex extracted from leaf litter in defined environments. Parasitoids were released at different densities to investigate density dependence in parasitation rates.

Although seven different species were released in our experiments, onlyPnigalio agraulesturned out to be responsible for biocontrol ofC. ohridella. We recorded parasitation rates of up to 35%. Overall, parasitation rates were independent of the leafminer density but increased fourfold if ten times more parasitoid individuals were released. Unfortunately, none of the parasitoid species could be established in the experimental units in the long run. Results are compared to other parasitoid-leafminer systems, and promotion of horse chestnut leafminer parasitoids to support natural selection and biological control of the horse chestnut leafminer is discussed.
Seasonal abundance and reproductive output of the dung fliesNeomyia cornicinaandN. viridescens(Diptera: Muscidae)
Authors: Wall R. , Anderson E. , Lee C.M.
Published: February 2008

The seasonal abundance and reproductive output of two common, but little studied, dung-breeding flies,Neomyia cornicinaandN. viridescens, were examined in artificial cow pats in pastures in southwest England in 2001 and 2004. In 2001, the numbers of bothNeomyiaspecies increased slowly over summer to show a sharp seasonal peak in late August and early September. There was no significant effect of mean temperature, mean relative humidity or dung water content on abundance or seasonally de-trended abundance. High levels of aggregation were seen between pats and, when present, greater numbers ofN. cornicinaemerged thanN. viridescens.Neomyia cornicinawas present in 13% of 240 artificial standardized pats put out in 2001, at a median of 19 adults per colonized pat;N.viridescenswas present in 8% of artificial pats at a median of three adults per colonized pat. In 2004,N. cornicinaemerged from 46% of the 94 artificial pats put out at a median of three adults per colonized pat, whileN. viridescensemerged from only 12% of pats at a median of one adult per colonized pat. Flies were also collected in 2004, using sticky-traps and hand nets. Again, free-flyingN. cornicinaappeared to be more abundant in the field thanN. viridescens; 162N. cornicinawere caught compared to 44N. viridescensover the same sampling period. The size of each adult female was recorded and ovarian dissection was used to determine the numbers of eggs matured. FemaleN. viridescenswere significantly larger than theN. cornicinaand matured significantly higher numbers of eggs. GravidN. viridescensmatured a mean of 37.1 (±16.9) eggs, whereas gravidN. cornicinamatured a mean of 28.8 (±13.2) eggs. The reasons why the larger, more fecund,N. viridescensadults are less abundant in the field or emerging from pats thanN. cornicinaare unknown. Further work is required to identify the nature and cause of the mortality experienced by the larvae of these species and the ecological differences and functional specialisation which allows co-existence to be maintained.
Resource allocation and bionomics of indigenous and exoticCotesia(Hymenoptera: Braconidae) species reared onSesamia calamistis
Authors: Hailemichael Y. , Schulthess F. , Smith J. , Overholt W. , Chabi-Olaye A.
Published: February 2008

The braconid larval parasitoidsCotesia chilonis(Matsumura),C. flavipesCameron and a strain ofCotesia sesamiae(Cameron) from coastal Kenya, reared at the International Centre of Insect Ecology and Physiology, were introduced at the International Institute of Tropical Agriculture in the Republic of Benin for suitability testing on West African stemborers prior to release.C. chiloniswas originally collected in Japan whileC. flavipeswas imported into Kenya from Pakistan. The host species used was the noctuidSesamia calamistis(Hampson), the most important noctuid maize pest in the region. All threeCotesiaspecies attacked and successfully developed in 2nd to 6th larval instar ofS.calamistisbut parasitoid-induced mortality was highest on second instars. On most instars,C. sesamiaeandC. flavipesproduced larger broods thanC. chilonis. Larvae parasitized byC. sesamiaedeveloped to the 6th instar and attained an average larval weight of 353 mg, while larvae parasitized byC. chilonisonly molted to the 4th instar and attained a maximum weight of 107 mg. The lower developmental threshold estimated from the non-linear regression of temperature on developmental rate was 15.9, 15.9 and 14.9°C forC. chilonis,C.sesamiaeandC. flavipes, respectively, while the maximum temperature was 34.2, 35.2 and 33.8°C, respectively. A maximum of four ovipositions were observed per female during a life span ranging from 1.3 days forC. chilonisandC. flavipesto 1.6 days forC.sesamiae. The largest adult progeny, intrinsic rate of increase and net reproductive rates were recorded at 28°C for all species. However, across temperatures,C. flavipesyielded the highest number of offspring, followed byC.sesamiaeandC. chilonis. The sex ratios did not vary significantly with species and temperature. Thus, the reproductive potentials ofC.sesamiaeandC. flavipeswere greater than that ofC. chilonis.
The analysis of self-diffusion and migration of rough spheres in nonlinear shear flow using a traction-corrected boundary element method
Authors: INGBER MARC S. , FENG SHIHAI , GRAHAM ALAN L. , BRENNER HOWARD
Published: February 2008

The phenomena of self-diffusion and migration of rough spheres in nonlinear shear flows are investigated using a new traction-corrected boundary element method (TC-BEM) in which the near-field asymptotics for the traction solution in the interstitial region between two nearly touching spheres is seamlessly coupled with a traditional direct boundary element method. The TC-BEM is extremely accurate in predicting particle trajectories, and hence can be used to calculate both the particle self-diffusivity and a newly defined migration diffusivity for dilute suspensions. The migration diffusivity is a function of a nonlinearity parameter characterizing the shear flow and arises from the net displacement of the centre of gravity of particle pairs. This net displacement of the centre of gravity of particle pairs does not occur for smooth particles, nor for rough particles in a linear shear flow. An explanation is provided for why two-particle interactions of rough spheres in a nonlinear shear flow result in particle migration.
Bifurcation analysis of steady Rayleigh–Bénard convection in a cubical cavity with conducting sidewalls
Authors: PUIGJANER DOLORS , HERRERO JOAN , SIMÓ CARLES , GIRALT FRANCESC
Published: February 2008

Natural convection in a cubical cavity heated from below with perfectly conducting sidewalls is investigated numerically. A parameter continuation procedure based on a Galerkin spectral method was applied to obtain the bifurcation diagrams for steady flow solutions over the region of Rayleigh numbers Ra ≤ 1.5 × 105 at Prandtl numbers Pr = 0.71 and 130. In both cases, the bifurcation diagrams were more complex than those previously reported for adiabatic sidewalls. Four and nine different convective solutions (without taking into account the solutions obtained by symmetry) that were stable over certain ranges of Ra were respectively identified at Pr = 0.71 and 130. The dependence of the bifurcation diagrams and of the topology of the flow patterns on the Prandtl number were also stronger in the case of conducting sidewalls. Most of the flow patterns investigated evolved to double toroid-like topologies with increasing Rayleigh number. This is especially noticeable at Pr = 130, where all flow patterns adopted double-toroid shapes that were superimposed on the characteristic flow patterns observed at values of Ra slightly above the respective bifurcation points where they originated. At sufficiently high Ra the double-toroid pattern configuration prevailed. This phenomenon, which has not been previously observed in the case of adiabatic lateral walls, is related to the thermal activity of the sidewalls, which locally extract/supply relatively large amounts of heat from/to the fluid. These predictions are consistent with experimental flow transitions and topologies reported in the literature. In addition, a complete bifurcation study in the two-dimensional (Ra, Pr)-plane was carried out for the flow pattern with an initial configuration of four connected half-rolls which was stable at both Pr = 0.71 and 130. Since the surface of Nu over the (Ra, Pr)-plane presented several folds and cusps, different regions were identified as a function of the number of particular realizations of this flow pattern, varying between zero and five. Three different regions of stability were identified for this particular flow pattern in the (Ra, Pr)-plane within the range of parameters investigated, i.e. Ra ≤ 1.5 × 105 and 0.71 ≤ Pr ≤ 130.
Abrupt transitions between gyroscopic and internal gravity waves: the mid-latitude case
Authors: VAN HAREN HANS
Published: February 2008

The large-scale vertical density stratification, represented by buoyancy frequency N, is generally very stable in the upper half of the ocean, and relatively weak in the lower half. However, closer inspection of density profiles demonstrates steps rather than a smooth increase with depth. As is demonstrated here using Richardson number, geostrophic balance and slantwise convective mixing arguments, these layers have a limited set of minimum, weak stratification, N-values Nmin indicating the transition between stably stratified and convective ‘homogeneous’ layers. Adopting the viewpoint that the transition occurs for neutral stability in the direction of Earth's rotation Ω instead of gravity g, three discrete states are hypothesized for mid-latitudes: (i) Nmin = 2fh under linear stability conditions, (ii) Nmin = fh(|ϕ| < 45°) and (iii) Nmin = 4fh, both under nonlinear stability, where horizontal component fh = 2Ω cos ϕ at latitude ϕ. The Nmin are not in terms of inertial frequency f = 2Ω sin ϕ, because the effect of fh is the tilting of vortex tubes away from the local vertical in the direction of Ω. The above explains very well deep-ocean North-Atlantic and Mediterranean observations on transitions in conductivity-temperature with depth profiles, inertial polarization and near-inertial shear. The latter peaks at sub-inertial 0.97f, which is associated with the lower inertio-gravity wave limit for Nmin = 4fh, thereby stressing the importance of fh for the dominant physics associated with mixing in the ocean.
Large-eddy simulation of a bi-periodic turbulent flow with effusion
Authors: MENDEZ S. , NICOUD F.
Published: February 2008

Large-eddy simulations of a generic turbulent flow with discrete effusion are reported. The computational domain is periodic in both streamwise and spanwise directions and contains both the injection and the suction sides. The blowing ratio is close to 1.2 while the Reynolds number in the aperture is of order 2600. The numerical results for this fully developed bi-periodic turbulent flow with effusion are compared to available experimental data from a large-scale spatially evolving isothermal configuration. It is shown that many features are shared by the two flow configurations. The main difference is related to the mean streamwise velocity profile, which is more flat for the bi-periodic situation where the cumulative effect of an infinite number of upstream jets is accounted for. The necessity of considering both sides of the plate is also established by analysing the vortical structure of the flow and some differences with the classical jet-in-crossflow case are highlighted. Finally, the numerical results are analysed in terms of wall modelling for full-coverage film cooling. For the operating point considered, it is demonstrated that the streamwise momentum flux is dominated by non-viscous effects, although the area where only the viscous shear stress contributes is very large given the small porosity value (4%).
Investigation of three-dimensional structure of fine scales in a turbulent jet by using cinematographic stereoscopic particle image velocimetry
Authors: GANAPATHISUBRAMANI B. , LAKSHMINARASIMHAN K. , CLEMENS N. T.
Published: February 2008

Cinematographic stereoscopic particle image velocimetry measurements were performed to resolve small and intermediate scales in the far field of an axisymmetric co-flowing jet. Measurements were performed in a plane normal to the axis of the jet and the time-resolved measurement was converted to quasi-instantaneous three-dimensional data by using Taylor's hypothesis. The quasi-instantaneous three-dimensional data enabled computation of all nine components of the velocity gradient tensor over a volume. The results based on statistical analysis of the data, including computation of joint p.d.f.s and conditional p.d.f.s of the principal strain rates, vorticity and dissipation, are all in agreement with previous numerical and experimental studies, which validates the quality of the quasi-instantaneous data. Instantaneous iso-surfaces of the principal intermediate strain rate (β) show that sheet-forming strain fields (i.e. β > 0) are themselves organized in the form of sheets, whereas line-forming strain fields (β < 0) are organized into smaller spotty structures (not lines). Iso-surfaces of swirling strength (a vortex identification parameter) in the volume reveal that, in agreement with direct numerical simulation results, the intense vortex structures are in the form of elongated ‘worms’ with characteristic diameter of approximately 10η and characteristic length of 60--100η. Iso-surfaces of intense dissipation show that the most dissipative structures are in the form of sheets and are associated with clusters of vortex tubes. Approximately half of the total dissipation occurs in structures that are generally sheet-like, whereas the other half occurs in broad indistinct structures. The largest length scale of dissipation sheets is of order 60η and the characteristic thickness (in a plane normal to the axis of the sheet) is about 10η. The range of scales between 10η (thickness of dissipation sheets, diameter of vortex tubes) to 60η (size of dissipation sheet or length of vortex tubes) is consistent with the bounds for the dissipation range in the energy and dissipation spectrum as inferred from the three-dimensional model energy spectrum.