bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of ethynylestradiol on the reproductive physiology in zebrafish (Danio rerio): Time dependency and reversibility
Authors: Van den Belt Kris , Wester Piet W. , van der Ven Leo T. M. , Verheyen Rudi , Witters Hilda
Published: March 2010

Environmental pollution with natural or synthetic estrogens may pose a serious threat to reproduction of wildlife species. This study describes the effects of 17-α-ethynylestradiol (EE2) on fish reproductive organs in a laboratory model. Adult zebrafish were semistatically exposed to nominal concentrations of 0, 10, and 25 ng/L EE2 for 24 d and then transferred to EE2-free medium. Gonadosomatic index (GSI), plasma vitellogenin concentration (VTG), and histology of the gonads (control and 10 ng/L only) were examined as a function of time. It was found that EE2 has an adverse impact on both male and female reproductive organs. Notably in females, gonadal changes were observed through histological evaluation after 3 d of exposure to 10 ng/L EE2, and this was followed by a reduction of GSI at day 6 of exposure. In males, a reduction of GSI and altered testis histology was found after 24 d of exposure to 10 ng/L. The observed effects on the ovary after EE2 exposure, combined with complete recovery after 24 d, is considered to be triggered by feedback at the level of the pituitary. In both males and females, VTG was induced in response to EE2 and normalized during the recovery period. The observed correlation between VTG and ovarian somatic index (OSI) demonstrates that excessive VTG induction may be predictive for adverse effects of EE2 on ovarian function in female zebrafish. These results indicate that long-term stimulation by synthetic estrogens such as EE2 might impair reproductive function in zebrafish in a reversible manner.
Postexposure feeding depression: A new toxicity endpoint for use in laboratory studies with Daphnia magna
Authors: McWilliam Ruth A. , Baird Donald J.
Published: March 2010

In situ bioassays with daphnids currently employ lethality as an endpoint, and although sublethal responses (reproduction and feeding rate) can be measured in the field, such endpoints pose major practical challenges. Previous studies have indicated that Daphnia magna exposed to toxic substances can exhibit delayed recovery in feeding behavior (postexposure feeding depression). This simple, robust response has the potential to be an ecologically relevant and potentially diagnostic endpoint. This study developed and tested the use of postexposure feeding depression as a toxicity endpoint in the laboratory environment. First, replicate numbers were manipulated to produce statistically reliable results. Second, postexposure feeding depression in D. magna was studied under laboratory conditions, by employing toxic substances with differing modes of action. Although most substances caused feeding inhibition during direct exposure, not all substances produced postexposure feeding depression. However, the use of lethality as a supplementary endpoint provided an alternative measure when no feeding depression was apparent after exposure. In combination, these endpoints offer a potentially more sensitive, ecologically relevant alternative to the use of lethality alone for in situ bioassay studies.
Relationship between lysosomal membrane destabilization and chemical body burden in eastern oysters (Crassostrea virginica) from Galveston Bay, Texas, USA
Authors: Hwang Hyun-Min , Wade Terry L. , Sericano Jose L.
Published: March 2010

Lysosomal destabilization was measured by using hemocytes of eastern oysters (Crassostrea virginica) collected along a chemical concentration gradient in Galveston Bay, Texas, USA. Results of the lysosomal response were compared to concentrations of organic compounds and trace elements in oyster tissue. Concentrations (on a dry-wt basis) ranged from 288 to 2,390 ng/g for polycyclic aromatic hydrocarbons (PAHs), 38 to 877 ng Sn/g for tri-n-butyltin (TBT), 60 to 562 ng/g for polyclorinated biphenyls (PCBs), and 7 to 71 ng/g for total DDT. Trace element concentrations (on a dry-wt basis) ranged from 1.1 to 4.0 μg/g for Cd, 105 to 229 μg/g for Cu, 212 to 868 μg/g for Al, and 1,200 to 8,180 μg/g for Zn. The percentage of destabilized lysosomes ranged from 34 to 81%. A significant positive correlation (p < 0.05) was observed between lysosomal destabilization and body burden of organic compounds (PAHs, PCBs, TBT, and chlorinated pesticides). No significant correlation was found between metal concentrations and lysosomal destabilization. Based on lysosomal destabilization, the study sites in Galveston Bay can be placed in one of three groups: healthy (Hanna Reef and Confederate Bay), moderately damaged (Offats Bayou and Todd's Dump), and highly damaged (Yacht Club and Ship Channel). Lysosomal destabilization that is consistent with toxic chemical body burdens supports previous observations that lysosomal membranes are damaged by toxic chemicals and indicates that this method can serve as an early screening tool to assess overall ecosystem health by using oysters.
Concentrations of trace elements in eggs and blood of spectacled and common eiders on the Yukon-Kuskokwim Delta, Alaska, USA
Authors: Grand James B. , Franson J. Christian , Flint Paul L. , Petersen Margaret R.
Published: March 2010

We examined the relations among nesting success, egg viability, and blood and egg concentrations of As, Cd, Pb, Hg, and Se in a threatened population of spectacled eiders (Somateria fischeri) and a sympatric population of common eiders (S. mollissima) on the Yukon-Kuskokwim Delta, Alaska, USA, during 1995 and 1996. During the early breeding season, males and females had mean Se concentrations in their blood of 19.2 μg/g and 12.8 μg/g wet weight, respectively. Blood Se concentrations of females were correlated with egg concentrations. During brood rearing, blood Se levels were higher in adult females than in ducklings. Blood concentrations of Pb in spectacled eider females were higher than in common eider females captured at hatching, but blood concentrations of Se were similar. Trace element concentrations were not related to nest success or egg viability. We submit that nest success and egg viability of spectacled eiders are not related to concentrations of the trace elements we measured. Because blood Se concentrations declined rapidly through the breeding season and were not related to nest success or egg viability, we suggest that spectacled eiders are exposed to high concentrations of Se during winter that pose little threat to this population.
Altering cytochrome P4501A activity affects polycyclic aromatic hydrocarbon metabolism and toxicity in rainbow trout (Oncorhynchus mykiss)
Authors: Hawkins Stephanie A. , Billiard Sonya M. , Tabash Samir P. , Brown R. Stephen , Hodson Peter V.
Published: March 2010

The polycyclic aromatic hydrocarbons (PAHs) phenanthrene and retene (7-isopropyl-1-methyl phenanthrene) are lethal to rainbow trout (Oncorhynchus mykiss) larvae during chronic exposures. Phenanthrene is a low-toxicity, non-cytochrome P4501A (CYP1A)—inducing compound that accumulates in fish tissues during exposure to lethal concentrations in water. Retene is a higher toxicity CYP1A-inducing compound that is not detectable in tissue at lethal exposure concentrations. The metabolism, excretion, and toxicity of retene and phenanthrene were examined in juvenile and larval rainbow trout during coexposure to the model CYP1A inducer β-naphthoflavone (βNF), or to the inducer-inhibitor piperonyl butoxide to determine if modulating CYP1A activity affected PAH metabolism and toxicity. Phenanthrene metabolism, excretion rate, and toxicity increased with coexposure to βNF. Piperonyl butoxide inhibited phenanthrene metabolism and reduced the excretion of all phenanthrene metabolites. As a consequence, embryo mortality rates increased but rates of sublethal effects did not. Coexposure of trout to retene and βNF caused no change in retene metabolism and excretion, but retene toxicity increased, perhaps due to additivity. Piperonyl butoxide inhibited retene metabolism, decreased the excretion of some retene metabolites while increasing the excretion of others, and increased the toxicity of retene. These results support the role of CYP1A activity in PAH metabolism and excretion, and the role of the CYP1A-generated metabolites of PAHs in chronic toxicity to larval fish.
Monitoring of aromatic monosulfonic acids in coastal waters by ion-pair liquid chromatography followed by electrospray-mass spectrometric detection
Authors: Alonso M. Carmen , Pocurull Eva , Marcé Rosa Maria , Borrull Francisco , Barceló Damià
Published: March 2010

Spain is one of the European countries that still discharges untreated wastewaters and sewage sludge into the sea. Aromatic monosulfonated compounds were detected in 36 seawater samples collected bimonthly on the Catalonian coast (Spain) over a period of 18 months. These compounds are of environmental concern because of their limited biodegradability and high mobility within the aquatic system. A method based on a sequential solid-phase extraction procedure (SSPE) followed by ion-pair liquid chromatography coupled to electrospray ionization-mass spectrometry (IPC-ESI-MS) in negative ionization mode was used to monitor aromatic monosulfonated compounds in the Catalonian coastal waters. Triethylamine (TEA) and acetic acid (HOAc) were used as volatile mobile-phase additives. A comparison of two polymeric solid-phase extraction (SPE) materials for the extraction of 15 aromatic monosulfonated compounds of environmental concern was performed. The investigated adsorbents were the poly-styrene-divinylbenzene materials Lichrolut EN, from Merck, and Isolute ENV+, from International Sorbent Technology (IST). The influence of the matrix on the analysis of seawater samples was also studied. Applications of the developed analytical procedure to seawater samples gave limits of detection (n = 3) ranging from 0.6 to 45 pg on column for the target analytes. Barcelona and Tarragona locations were chosen along the Catalonian coast as sampling sites because of their large sewage discharges and intensive industrial activities. Samples were acquired from submarine outfalls of two rivers, Besos and Llobregat, located in the north and south of Barcelona city, respectively. Samples from petrochemical industry submarine outfalls located near the commercial port of Tarragona were also studied. Concentrations of benzenesulfonates (BS) and naphthalenesulfonates (NS) were of the order of ng/ml. Most of the collected samples were found to contain both isomers of mononaphthalenesulfonate. The study showed that these compounds can contaminate marine coastal waters.
Sorption and dialysis experiments to assess the binding of phenolic xenobiotics to dissolved organic matter in soil
Authors: Höllrigl-Rosta Andreas , Vinken Ralph , Lenz Markus , Schäffer Andreas
Published: March 2010

The binding of two phenolic compounds, nonylphenol (NP) and bisphenol A (BPA), and the herbicide metabolite hydroxydesethyl terbuthylazine (HDT) to dissolved organic matter (DOM) as well as its impact on the environmental fate of the compounds in soil have been investigated. In sorption studies with an acidic silty loam soil and a neutral loam soil, no impact of added DOM on adsorption and desorption coefficients was observed. Adsorption coefficients normalized to soil organic carbon (Koc) of the compounds on the loamy silt soil spanned three orders of magnitude: 90, 890, and 9,140 L/kg for HDT, BPA, and NP, respectively. Significantly lower Koc values for HDT on the neutral loam soil as compared to the acidic loamy silt soil indicated additional polar interactions between the latter and the basic herbicide metabolite. In dialysis experiments with fulvic acid from silty loam soil (FA) and peat humic acid (HA), a formation of analyte-DOM associates was observed only for HA. The degree of association was characterized by distribution coefficients normalized to the dissolved organic carbon concentration (KDOC). Values for NP (8,970 L/kg) and BPA (860 L/kg) corresponded with the respective soil sorption coefficients, suggesting similar binding mechanisms in both cases.
Pesticide risk assessment in a lagoon ecosystem. Part I: Exposure assessment
Authors: Villa Sara , Finizio Antonio , Vighi Marco
Published: March 2010

This work is the first step of a research project on pesticide risk assessment for a coastal lagoon ecosystem (Orbetello lagoon, central Italy). Pesticide exposure was evaluated by means of predictive and experimental approaches. Predicted environmental concentrations (PECs) for water and sediments were estimated using fugacity-based multimedia models. Pesticide loads were quantified through a study of the use to which agricultural land was put in the study area. Multimedia fate models were used to predict the environmental concentration of 29 active ingredients (mainly insecticides and herbicides) selected among the most widely used within the catchment basin. Worst-case environmental scenarios were developed for the application of these models, in agreement with the precautionary principle. Experimental monitoring was performed on 10 selected chemicals. To assess the value and limitations of predictive and experimental approaches, calculated PECs and monitoring results were compared and discussed. Combined modeling and monitoring approaches have been found to be the best way to date to assess proper exposure.
Creosote toxicity to photosynthesis and plant growth in aquatic microcosms
Authors: Marwood Christopher A. , Bestari K. T. Jim , Gensemer Robert W. , Solomon Keith R. , Greenberg Bruce M.
Published: March 2010

Measurement of contaminant effects becomes progressively more difficult at higher levels of ecological organization [1]. Bioindicators are rapid physiological or biochemical assays that provide a convenient means for detecting the exposure or effects of environmental contaminants to organisms, even if the toxicant is unknown. Many potential bioindicator assays are available, but the primary impediment to their widespread use in risk assessment is the lack of a demonstrated link between effects at the suborganism level with effects at the individual level and with higher levels of biological organization, such as populations or communities [2]. A bioindicator with a defined link to effects on growth or reproduction can be used in a predictive manner to assess potential impacts of a contaminant on populations of organisms. Effects of a stressor on bioindicator endpoints, which are easily measurable under controlled conditions, can then be extrapolated to the environment if the effects at the suborganism level are consistent with, and can be related to, effects at the whole-organism and population levels.
Bioturbation effects on cadmium and zinc transfers from a contaminated sediment and on metal bioavailability to benthic bivalves
Authors: Ciutat Aurélie , Boudou Alain
Published: March 2010

The two main objectives of this study were to compare cadmium and zinc fluxes from a contaminated sediment to the water column in bioturbated and unbioturbated systems and jointly to analyze accumulation kinetics of these released metals by benthic filter-feeder bivalves. The experimental approach was based on indoor microcosms containing a two-compartment biotope: natural contaminated sediment (45 ± 5 μg Cd/g, dry wt, and 1,938 ± 56 μg Zn/g, dry wt) and water column. Four experimental conditions were studied: no organism added to the sediment-water biotope, presence of bivalves Corbicula fluminea, presence of Hexagenia rigida nymphs (bioturbation source), and presence of C. fluminea and H. rigida simultaneously. Results reveal that bioturbation produces a significant metal release into the water column via the resuspended sediment particles. The use of C. fluminea as an indicator of transferred metals in the water column shows that the metal bioavailability is very limited, quantities of cadmium and zinc bioaccumulated in the soft bodies being less than those measured in unbioturbated systems. This experimental study demonstrates that only the dissolved fraction resulting from diffusive metal fluxes across the sediment-water interface is bioavailable for this bivalve species.
Evaluationen in der Regionalentwicklung
Authors: Wiechmann Thorsten , Beier Markus
Published: March 2010

In the 1990ies Regional Development Concepts have become a mainstream tool in the German Länder, mostly without a systematic review of their performance. Before this background the article deals with the neglected challenge of evaluations in regional development. Introductorily the need for and the restrictions of evaluations in regional development are described (Chapter 1). Starting from fundamental considerations on policy and programme evaluations (Chapter 2) and the state of art in evaluation of regional development in Germany (Chapter 3) a proposal for a method to evaluate Regional Development Concepts is outlined (Chapter 4) and conclusions are drawn (Chapter 5).
Regionalmanagement — Potenziale, Grenzen und Perspektiven
Authors: Schäffer Verena
Published: March 2010

The concept of regional management has gained more and more importance over the last decade. Based on empirical studies of three regions in Saxony-Anhalt, the concept of regional management was closely examined from a theoretical and practical perspective to determine the efficiency of this concept. The results of this analysis are presented in this essay. The structures of the regional management of the three case studies are presented and quality criteria are identified. Problems of implementation are also indicated. On this basis, recommendations are drawn for the future implementation of regional management concepts.
Entwicklung des großflächigen Einzelhandels in regionaler Verantwortung
Authors: Fuchs Oliver
Published: March 2010

Unter Federführung der regionalen Strukturkonferenz Ost-Friesland haben vier Landkreise und zwei kreisfreie Städte mit einer Abstimmung ihrer großflächigen Einzelhandelsentwicklung begonnen. p] Nach einer rund zweij\:ahrigen Planungsphase, welche neben einer Bestandsaufnahme der Einzelhandelssituation vor allem die Aufstellung eines interkommunalen Kooperationsund Abstimmungsverfahrens beinhaltete, konnte Anfang 2004 eine interkommunale Vereinbarung geschlossen werden, die den Beginn der Verfahrensimplikation in der Region markierte.

Der Beitrag beschreibt Ausgangssituation, Zielstellung und Methodik des Verfahrens und geht darüber hinaus in einem Zwischenfazit auf erste Erfahrungen in realen Anwendungsfällen ein.
Regionalentwicklung in Mittel- und Osteuropa im Spannungsfeld von Transformation und Integration am Beispiel Polens
Authors: Abraham Thomas , W. Ese Thiemo
Published: March 2010

The transformation processes unleashed in Central and Eastern Europe with the collapse of the communist system have had far-reaching effects on the countries concerned: both at national level in respect of the level of economic activity, and at regional level with regard to distribution. Taking Poland as an example, this article draws on a number of theories of regional economy to show how disparities will be heightened over the medium term, and that convergence is only likely in the long term. Neither national regional policy, which is only slowly starting to get off the ground, nor the increasing support provided by EU regional policy is capable of offsetting divergent development, as political priority is given to national convergence vis-à-vis EU member states.
Indikatoren für eine nachhaltige Entwicklung
Authors: Birkmann Jörn
Published: March 2010

The paradigm of sustainable development, which since 1998 has been enshrined in the Federal Regional Planning Act (the Raumordnungsgesetz), has not so far been implemented to anything approaching a satisfactory degree. This is particularly true within local authorities, which were named explicitly in Agenda 21 as major agents of implementation. One important approach toward continuous monitoring of the implementation of a concept of development aimed at achieving sustainability is considered to lie in the use of indicators, which are currently a subject of discussion at all levels of spatial planning. The present contribution develops building blocks for a system of local indicators of sustainability. A case study on implementation of the indicator system provides the basis for outlining the problems and shortcomings associated with current information and data systems at local-authority level.
Perspektiven der westdeutschen Verdichtungsräume
Authors: Lorenz Cornelia
Published: March 2010

The development pressure on agglomerations in the western part of Germany will continue into the future. It was in order to counter the negative trends associated with this situation that the spatial order principles of settlement density, mixed uses and polycentrality were developed. However, these strategies can only be implemented through a tier of administration which covers the expanding conurbation in its entirety. Consequently, this calls for a reorganisation of the regional planning system in which strategies are developed in close co-operation with local authorities to overcome these problems and to equip it with the instruments it requires to implement these strategies.
Das Studium der Fachrichtung Diplom-Geographie mit dem Schwerpunkt Raumplanung an der Universität Bayreuth
Authors: Maier Jörg
Published: March 2010

Proceeding from an account of the requirements of professional practice, this article describes the organisation and the content of the course in spatial planning and the qualifications which it leads to. This is followed by an analysis of the types of employment in this field which graduates of this course over the last two decades have entered. One finding stands out: whereas graduates in the early days tended to find employment in the public service, more recently the majority of graduates have taken up positions in the private sector.
Ausbildung für die Raumplanung
Authors: Scholl Bernd
Published: March 2010

At the University of Karlsruhe there is a long tradition of providing courses in Spatial Planning and, together with Infrastructure Planning, it now constitutes a distinct option for specialisation in the Faculty of Civil Engineering. As far as tuition is concerned, methodbased subject-areas occupy a special position alongside the core subjects required for Urban Development and Regional Planning. The course aims to enable students to work independently towards developing strategies for solving complex tasks in the field of Spatial Planning, to identify the suitability of instruments and procedures and to apply the knowledge they have acquired within a problem-orientated approach. In order to achieve this, the course attaches great importance to the integrated study project. This module, which is offered in every year of the course, focusing each time on a different issue of current relevance in spatial development, is conceived as a joint undertaking involving all of the chairs associated with the option.
„Schlanker Regionalplan” — ein neuer Weg?
Authors: Fürst Dietrich , Peithmann Ortwin
Published: March 2010

The authors point out the links between the proposed “lean regional plan” and various strands of the current discussion on reforming public administration. They place the regional plan within a dynamic context incorporating the contiguous instances of spatial and sectoral planning. From this they go on to derive three basic models of reciprocal displacement, which might provide a starting point for a more long-term overhaul of the German planning system. In the five proposals they put forward, the authors describe possible ways of reducing the content and procedures of regional planning in the shorter term without diminishing the degree of control afforded by the planning system.
Tertiarisierung ohne wettbewerbsfähige Industriebasis?
Authors: Meyer Bernd , Ewerhart Georg , Siebe Thomas
Published: March 2010

Within the discussion on strategies to bring down unemployment, great hopes have been placed in the services sector. Many people have already come to see services as the powerhouse of economic growth in the Federal Republic of Germany. However, this thesis fails to take account of the mutual dependencies which exist between the secondary and tertiary sectors. Empirical analysis for the Münster region administrative district illustrates the importance of the role played by upstream relationships between these two sectors. Consequently, the successes of the services sector in terms of job-creation are dependent on the competitiveness of the region’s industries. Providing support for the services sector without at the same time taking measures to nurture the industrial base would thus appear to be a highly questionable strategy.
Regionale Leitbilder
Authors: Hein Ekkehard
Published: March 2010

Regional visions — or leitbilder — mark out an orientational framework for working towards the desired state of development. Development visions for the region pick up key elements of the regional plan, which they then build upon from a development perspective. Circumstances permitting, the agencies of regional planning draw up these models and are involved in their implementation. In the mid nineties, following a particularly dynamic period of development, the Heilbronn-Franken Region underwent quite fundamental structural change. The region looked to interregional discussion for guidance and developed its “Visions for the Heilbronn-Franken Region”. The requisite target orientations are brought together in the leitmotif “Innovation and Networking: the Heilbronn-Franken Region and its Future Viability”.
Innovation und Konsens — ein Widerspruch?
Authors: Fürst Dietrich , Knieling Jörg
Published: March 2010

The article considers the question how the dilemma of many regions can be solved that a conflict exists between the claim for an orientation towards innovation and the necessity of seeking a consensus between the regional actors. Innovation processes and the creation of consensus are two central functions of modern regional development (chapter 2). However, if one considers the logic of innovation and consensus, it becomes clear that both do not necessarily harmonise (chapter 3). The presented approaches for the separation as well as for the alignment of innovation and the finding of consensus structure the field of possible solutions in order to resolve the contradictions (chapter 4). The approaches for solutions can help to organise regional development processes more intelligently and with a greater orientation towards success (chapter 5).
Technologie- und Gründerzentren und regionales Wissenspotenzial
Authors: Liefner Ingo
Published: March 2010

Science parks (Technologie und Gründerzentren) aim at supporting newly founded high-tech companies. Thus, they are meant to contribute to technology transfer from universities and other public research institutes to companies. Theoretical considerations suggest that the amount of knowledge embodied within local universities and companies is a key determinant for technology transfer. This article analyzes whether differences in the regional knowledge potential are reflected in the technological level of firms supported by sience parks. This hypothesis can be confirmed: Firms in regions with high local knowledge potential show significantly higher technological levels regardless of their age, field, and size.
Umsetzung der Integration von Raumplanung und Verkehr in Hessen
Authors: Bosserhoff Dietmar
Published: March 2010

The essay shows that the state of Hessen sets great store by the integration of land use and transportation planning in order to minimize the volume of vehicular traffic. In addition strategies for implementing and experience made are listed. Hessen introduced a public concern, informed the planning institutions (investors/ the integration municipalities) about strategies and measures of the integration and developed a method for estimating the volume of vehicular traffic generated by land use projects. An essential strategy of the integration is to arrange new land use close to railway stations, yet in order to reach optimal results it is necessary to improve the railway service, too.
STADT. To whom it may concern
Authors: Doehler-Behzadi Marta
Published: March 2010

Policy and practice perspective
Examining the Potential of Community‐Based After‐School Programs for Latino Youth
Authors: Riggs Nathaniel R. , Bohnert Amy M. , Guzman Maria D. , Davidson Denise
Published: March 2010

Results are presented from two pilot studies examining the potential influence of community‐based after‐school programs (ASPs) on regionally diverse Latino youth of varying ages. Study 1 examined relations between dimensions of ASP attendance and content, and ethnic identity development, and self‐worth in urban Latino adolescents. In this study, higher ratings of the ASP’s emphasis on ethnic socialization were associated with a more developed ethnic identity, while greater intensity of ASP participation and perceptions of ASP quality were associated with higher levels of self‐worth. Study 2 examined relations between ASP participation and development of concentration and emotion regulation skills in rural Latino grade‐school youth. In this study, youth who regularly attended the ASP demonstrated significantly better concentration and regulation skills than those who did not regularly attend, if they exhibited preexisting concentration and regulation problems. Findings illustrate how ASPs with varying strategies, activities, and assessment tools can be evaluated in the interest of designing future large‐scale investigations into ASPs and Latino positive youth development.
A Modified Surgical Technique for Lengthening of a Metatarsal Using an External Fixator
Authors: Scher David M. , Blyakher Arkady , Krantzow Michael
Published: March 2010

Brachymetatarsia is a congenital or developmental condition that results in a short metatarsal. Problems that arise from this condition can include pain, difficulty with shoe wear, and cosmetic concerns. Multiple techniques have been described that successfully correct the deformity, including both acute and gradual distraction. We describe a modification of the technique of gradual lengthening by way of distraction osteogenesis in which an axial transarticular K-wire is incorporated into a monolateral frame, thereby increasing the stability of the construct and potentially minimizing complications.
Mixed Micellization Properties of Nonionic Fluorocarbon/Cationic Hydrocarbon Surfactants
Authors: Bélarbi Hayet , Bendedouch Dalila , Bouanani Farida
Published: March 2010

The physico‐chemical properties of mixed surfactant aqueous solutions at various proportions of dodecyltrimethyl ammonium bromide DTAB and undecafluoro n‐pentyl decaoxyethylene ether C5F11EO10 have been investigated at 25 °C using surface tension and conductivity measurements. The critical micelle concentration and superficial minimum tension have been experimentally estimated for different DTAB molar fractions. The micellar composition and mutual interaction parameters have been deduced on the basis the theoretical treatments proposed by Clint, Rubingh, and Motomura. The results show a significant synergism effect at about equimolarity of DTAB/C5F11EO10 system probably due to the efficient electrostatic self‐repulsion reduction between DTAB cationic head groups related to the presence of the nonionic surfactant in the mixed micelles.
Marangoni effects caused by contaminants adsorbed on bubble surfaces
Authors: LAKSHMANAN PETER , EHRHARD PETER
Published: March 2010

The influence of Marangoni stresses, caused by contaminants adsorbed on the surface of small air bubbles, rising in water, is examined by numerical simulations. A modified level set method is used to represent the deformable bubble interface, extended by a model for the contaminant transport on the bubble surface. We show that surface tension variations of less than 2% are sufficient to generate Marangoni stresses that are strong enough to change the rising characteristics of a bubble to that of a corresponding solid particle. In such situations, we find that the bubble surface is fully covered with contaminant and the shear stress profile resembles the shear stress profile around a solid sphere.
Monolayer slip effects on the dynamics of a lipid bilayer vesicle in a viscous flow
Authors: SCHWALBE JONATHAN T. , VLAHOVSKA PETIA M. , MIKSIS MICHAEL J.
Published: March 2010

The dynamics of a closed lipid bilayer membrane (a vesicle) in a linear viscous flow is investigated. The model accounts for the transport of lipids along each monolayer and intermonolayer friction, as well as the membrane fluidity, incompressibility and resistance to bending. Assuming a nearly spherical vesicle, the leading order analysis results in a nonlinear coupled system of equations for the dynamics of the shape and the bilayer density difference. Multiple solution states are found as a function of viscosity ratio and the monolayer slip coefficient. The dynamics and stability of these solutions is discussed.
Free streamline flows with singularities
Authors: EGGERS J. , SMITH A. F.
Published: March 2010

We rederive and expand upon a method for finding solutions to the two-dimensional irrotational (inviscid) flow equations in the presence of a free surface, found by Hopkinson. This method allows the flow to be driven by placing singularities, like sources or vortices, in the interior of the flow domain. We then apply the method to find a number of novel solutions: separated flow driven by a source, vortices behind a plate and free-surface flow stirred by a double vortex. Free surfaces generically exhibit cusp singularities with a 2/3 power index, similar to those found in very viscous flow.
Drag reduction of flexible plates by reconfiguration
Authors: GOSSELIN FRÉDÉRICK , de LANGRE EMMANUEL , MACHADO-ALMEIDA BRUNO A.
Published: March 2010

Through an extensive and systematic experimental investigation of two geometries of flexible plates in air, it is shown that a properly defined scaled Cauchy number allows collapsing all drag measurements of the reconfiguration number. In the asymptotic regime of large deformation, it is shown that the Vogel exponents that scale the drag with the flow velocity for different geometries of plates can be predicted with a simple dimensional analysis reasoning. These predicted Vogel exponents are in agreement with previously published models of reconfiguration. The mechanisms responsible for reconfiguration, namely area reduction and streamlining, are studied with the help of a simple model for flexible plates based on an empirical drag formulation. The model predicts well the reconfiguration observed in the experiments and shows that for a rectangular plate, the effect of streamlining is prominent at the onset of reconfiguration, but area reduction dominates in the regime of large deformation. Additionally, the model demonstrates for both geometries of plates that the reconfiguration cannot be described by a single value of the Vogel exponent. The Vogel exponent asymptotically approaches constant values for small and for very large scaled Cauchy numbers, but in between both extremes it varies significantly over a large range of scaled Cauchy number.
Stability of constrained cylindrical interfaces and the torus lift of Plateau–Rayleigh
Authors: BOSTWICK J. B. , STEEN P. H.
Published: March 2010

Surface tension acting at a cylindrical interface holds an underlying liquid in motionless equilibrium. This static base state is subject to dynamic capillary instability, including Plateau–Rayleigh breakup. If the interface is partially supported by a cylindrical cup-like solid, the extent of the wetting contact can significantly influence the dynamics and the stability of the configuration. The equation for the motion of small disturbances is formulated as an eigenvalue equation on linear operators. A solution is constructed on a constrained function space using a Rayleigh–Ritz procedure. The influence of the extent-of-constraint on the dispersion relation and on modal structures is reported. In the extreme, the support reduces to a wire, aligned axially, and just touching the interface. From prior work, this constraint is known to stabilize the Plateau–Rayleigh limit by some 13%. We report the wavenumber of maximum growth and estimate the time to breakup. The constraint is then bent in-plane to add a weak secondary curvature to the now nearly cylindrical base state. This is referred to as the torus lift of the cylinder. The static stability of these toroidal equilibria, calculated using a perturbation approach, shows that the position of constraint is crucial – constraint can stabilize (outside) or destabilize (inside). The combined influence of secondary curvature and wire constraint on the Plateau–Rayleigh limit is tracked. Finally, attention is restricted to constraints that yield a lens-like cylindrical meniscus. For these lenses, the torus lift is used as apparatus along with a symmetrization procedure to prove a large-amplitude static stability result. Our study is conveniently framed by a classic paper on rivulets by Davis (J. Fluid Mech., vol. 98, 1980, p. 225).
Experimental study of flow fields in an airway closure model
Authors: BIAN S. , TAI C.-F. , HALPERN D. , ZHENG Y. , GROTBERG J. B.
Published: March 2010

The liquid lining in small human airways can become unstable and form liquid plugs that close off the airways. Bench-top experiments have been performed in a glass capillary tube as a model airway to study the airway instability and the flow-induced stresses on the airway walls. A microscale particle image velocimetry system is used to visualize quantitatively the flow fields during the dynamic process of airway closure. An annular film is formed by injecting low-viscosity Si-oil into the glycerol-filled capillary tube. The viscosity ratio between these two fluids is similar to that between water and air. The thickness of the film varies with the infusion rate of the core fluid, which is controlled by a syringe pump. After a uniform film is formed, the syringe pump is shut off so that the core flow speed is close to zero during closure. Instantaneous velocity fields in the annular film at various stages of airway closure are computed from the images and analysed. The wall shear stress at the instant when a liquid plug forms is found to be approximately one order of magnitude higher than the exponential growth period before closure. Within the short time span of the closure process, there are large wall shear stress fluctuations. Furthermore, dramatic velocity changes in the film flow during closure indicate a steep normal stress gradient on the airway wall. The experimental results show that the wall shear stress during closure can be high enough to injure airway epithelial cells. An airway that experiences closure and reopening cyclically during breathing could be injured from fluid forces during both phases of the cycle (i.e. inspiration and expiration).
On the possibility of refraction of dust acoustic waves
Authors: ROSENBERG M. , MERLINO R. L. , SHUKLA P. K.
Published: March 2010

We theoretically investigate conditions for the refraction of long-wavelength dust acoustic waves by arrays of periodic cylinders in a dusty plasma. This is based on a recent analysis of the refraction of shallow water waves by periodic cylinder arrays (Hu and Chan, Phys. Rev. Lett.95 (2005), 154501). In the dusty plasma case, however, the boundary conditions involve the formation of voids around the cylinders. Possible experimental conditions are discussed.
Treating irritable bowel syndrome with probiotics: the evidence
Authors: Parkes G. C. , Sanderson J. D. , Whelan K.
Published: March 2010

Irritable bowel syndrome (IBS) is a disorder of chronic abdominal pain, altered bowel habit and abdominal distension. It is the commonest cause of referral to gastroenterologists in the developed world and yet current therapeutic strategies are often unsatisfactory. There is now increasing evidence linking alterations in the gastrointestinal (GI) microbiota and IBS. Changes in faecal and mucosa-associated microbiota, post-infectious IBS, a link with small intestinal bacterial overgrowth and an up-regulation of the GI mucosal immune system all suggest a role for the GI microbiota in the pathogenesis of IBS. Given this evidence, therapeutic alteration of the GI microbiota by probiotic bacteria could be beneficial. The present paper establishes an aetiological framework for the use of probiotics in IBS and comprehensively reviews randomised placebo-controlled trials of probiotics in IBS using multiple electronic databases. It highlights safety concerns over the use of probiotics and attempts to establish guidelines for their use in IBS in both primary and secondary care.
Benjamin Leigh Smith's third Arctic expedition: Svalbard, 1873
Authors: Capelotti P.J.
Published: March 2010

In 1873, the British explorer Benjamin Leigh Smith concluded the private oceanographic and geographical explorations in the seas around Svalbard that he had begun in 1871 and continued in 1872. The logistics of the 1873 expedition, however, were far more complicated than those of the first two voyages. Rather than using a single ship as he had done with the sailing vessel Samson the previous summers, Leigh Smith chartered James Lamont's Arctic steamer Diana and employed Samson as a reserve supply tender. With the added supplies Samson afforded, Leigh Smith planned to round the northeast limit of Svalbard, which he had discovered in 1871, and survey Kong Karls Land. Among those invited to join to expedition was a twenty-three-year-old member of the Royal Engineers, Lieutenant Herbert C. Chermside, who would visit the Arctic for the first and last time in a long life of military service. It was to Chermside that Leigh Smith entrusted the keeping of the expedition's logbooks. These three unpublished journals, along with a log kept by Samson's captain, William Walker, provide details of an expedition that, while it failed in its primary objective to round Nordaustlandet, did succeed in relieving Adolf Erik Nordenskiöld's Swedish polar expedition beset near Mosselbukta. It also maintained an array of contacts with whalers and sealers, for example the Peterhead whaler David Gray and the Norwegian skipper Frederick Christian Mack, regarding local conditions around Svalbard. At Augustabukta, Chermside's observations of uplifted skeletons of remotely harvested whales give estimated death ranges of between 1569–1691 and 1764–1807. The expedition would end with a major island in Svalbard being named for Chermside.
Symptoms of depression and anxiety, and change in body mass index from adolescence to adulthood: results from a British birth cohort
Authors: Gaysina D. , Hotopf M. , Richards M. , Colman I. , Kuh D. , Hardy R.
Published: March 2010

Background

Depression and anxiety have been shown to be associated with obesity and underweight, but little is known about how the relationship varies across the life course, from adolescence through adulthood. We aimed to investigate the association between adolescent- and adult-onset affective symptoms and body mass index (BMI) change from age 15 to 53 years.

Method

We used data from a British birth cohort born in 1946 and followed up ever since. The relationship between affective symptom profiles, distinguishing adolescent-onset and adult-onset symptoms, and BMI change from adolescence to age 53 years was investigated using multilevel models.

Results

Women with adolescent-onset symptoms had lower mean BMI at age 15 years, faster rates of increase across adulthood, and higher BMI at age 53 years than those with no symptoms. Men with adolescent-onset symptoms had lower BMI at all ages from 15 to 53 years. The BMI trajectories of men and women with adult-onset symptoms did not differ from those with absence of symptoms at all ages.

Conclusions

The relationship between affective symptoms and change in BMI varies by sex and age at onset of symptoms. Adolescence may be an important period for the development of the association between affective symptoms and weight gain in girls. Intervention to prevent increases in BMI across adult life in women with adolescent-onset symptoms, even if they are not overweight at this age, should be considered.
THE ASYMPTOTIC EQUIPARTITION PROPERTY FOR ASYMPTOTIC CIRCULAR MARKOV CHAINS
Authors: Zhong Pingping , Yang Weiguo , Liang Peipei
Published: March 2010

In this article, we study the asymptotic equipartition property (AEP) for asymptotic circular Markov chains. First, the definition of an asymptotic circular Markov chain is introduced. Then by applying the limit property for the bivariate functions of nonhomogeneous Markov chains, the strong limit theorem on the frequencies of occurrence of states for asymptotic circular Markov chains is established. Next, the strong law of large numbers on the frequencies of occurrence of states for asymptotic circular Markov chains is obtained. Finally, we prove the AEP for asymptotic circular Markov chains.
Primary immunodeficiencies associated with DNA-repair disorders
Authors: Slatter Mary A. , Gennery Andrew R.
Published: March 2010

DNA-repair pathways recognise and repair DNA damaged by exogenous and endogenous agents to maintain genomic integrity. Defects in these pathways lead to replication errors, loss or rearrangement of genomic material and eventually cell death or carcinogenesis. The creation of diverse lymphocyte receptors to identify potential pathogens requires breaking and randomly resorting gene segments encoding antigen receptors. Subsequent repair of the gene segments utilises ubiquitous DNA-repair proteins. Individuals with defective repair pathways are found to be immunodeficient and many are radiosensitive. The role of repair proteins in the development of adaptive immunity by VDJ recombination, antibody isotype class switching and affinity maturation by somatic hypermutation has become clearer over the past few years, partly because of identification of the genes involved in human disease. We describe the mechanisms involved in the development of adaptive immunity relating to DNA repair, and the clinical consequences and treatment of the primary immunodeficiency resulting from such defects.
Propagating rift model for the V‐shaped ridges south of Iceland
Authors: Hey Richard , Martinez Fernando , Höskuldsson Ármann , Benediktsdóttir Ásdís
Published: March 2010

We present new marine geophysical data which constrain the seafloor spreading history of the Reykjanes Ridge near Iceland and the origin of its flanking V‐shaped topographic and gravity ridges. Contrary to the geometry assumed in pulsing plume models, the V‐shaped ridges are not symmetric about the Reykjanes Ridge axis, and seafloor spreading has not been symmetric about a stable axis. Thus, existing models must at least be modified to include an additional asymmetry‐producing mechanism; the best understood and documented such mechanism is rift propagation. One possibility is that plume pulses drive the propagators. However, rift propagation also produces V‐shaped wakes with crustal thickness variations, suggesting the possibility that a pulsing Iceland plume might not be necessary to explain the Reykjanes V‐shaped ridges, scarps, and troughs.