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Kinds of Stands Terms modified by Stands Selected AbstractsEffect of apolipoprotein E on biomarkers of amyloid load and neuronal pathology in Alzheimer diseaseANNALS OF NEUROLOGY, Issue 3 2010Prashanthi Vemuri PhD Objective To study the effect of apolipoprotein E ,4 status on biomarkers of neurodegeneration (atrophy on magnetic resonance imaging [MRI]), neuronal injury (cerebrospinal fluid [CSF] t-tau), and brain A, amyloid load (CSF A,1,42) in cognitively normal subjects (CN), amnestic subjects with mild cognitive impairment (aMCI), and patients with Alzheimer disease (AD). Methods We included all 399 subjects (109 CN, 192 aMCI, 98 AD) from the Alzheimer's Disease Neuroimaging Initiative study with baseline CSF and MRI scans. Structural Abnormality Index (STAND) scores, which reflect the degree of AD-like anatomic features on MRI, were computed for each subject. Results A clear ,4 allele dose effect was seen on CSF A,1,42 levels within each clinical group. In addition, the proportion of the variability in A,1,42 levels explained by APOE ,4 dose was significantly greater than the proportion of the variability explained by clinical diagnosis. On the other hand, the proportion of the variability in CSF t-tau and MRI atrophy explained by clinical diagnosis was greater than the proportion of the variability explained by APOE ,4 dose; however, this effect was only significant for STAND scores. Interpretation Low CSF A,1,42 (surrogate for A, amyloid load) is more closely linked to the presence of APOE ,4 than to clinical status. In contrast, MRI atrophy (surrogate for neurodegeneration) is closely linked with cognitive impairment, whereas its association with APOE ,4 is weaker. The data in this paper support a model of AD in which CSF A,1,42 is the earliest of the 3 biomarkers examined to become abnormal in both APOE carriers and noncarriers. ANN NEUROL 2010;67:308,316 [source] Grundlegende Erläuterung zum modifizierten Zulassungsverfahren für Feuerschutzabschlüsse (Stand: 1.DIBT MITTEILUNGEN (FORMERLY-MITTEILUNGEN DEUT INST FUER BAUTECHNIK), Issue 1 2006Dezember 2005) Die Ergebnisse aus der Erprobung des modifizierten Zulassungsverfahrens für Feuerschutzabschlüsse, gewonnen in Zusammenarbeit der am Zulassungsverfahren Beteiligten (Antragsteller, Prüfstelle und DIBt), werden im Folgenden grundlegend erläutert. Sie werden , nach Beratung im dafür zuständigen Sachverständigenausschuss (SVA) "Feuerschutzabschlüsse" , als Zulassungsgrundsätze die Grundlage bilden für die Erteilung von allgemeinen bauaufsichtlichen Zulassungen durch das Deutsche Institut für Bautechnik. Die Erkenntnisse aus der Erprobungsphase sind daher in ihrem Aufbau bereits als Zulassungsgrundsätze zusammengefasst. [source] Standard Setters: Stand Up and Take a Stand!EDUCATIONAL MEASUREMENT: ISSUES AND PRACTICE, Issue 1 2008Barbara S. Plake This 2006 NCME Career Award Address presents observations made over a career in the field of standard setting, summarizes the status of current research, and makes recommendations for future research. [source] On Imagination: Reconciling Knowledge and Life, or What Does "Gregory Bateson" Stand for?FAMILY PROCESS, Issue 4 2004Marcelo Pakman This article presents a reading of Gregory Bateson's oeuvre, focusing on his interest in the representational gap between map and territory, and its importance in the development of his redefinition of the concept of "mind," his new discipline called "ecology of ideas," and a methodology congruent to it based on the logics of metaphor. Inquiries on three initial stories from different domains allow the use of homologies between form and content in the article. This reading of Bateson's oeuvre stresses his questioning (like Derrida's) of the metaphysics of presence on which Western philosophy has been mostly based, and of the central role of imagination as a balancing factor for a family therapy that he both contributed to and saw with reservations. [source] Tapovan-Vishnugad hydroelectric power project , experience with TBM excavation under high rock cover / . Tapovan-Vishnugad Wasserkraftwerk , Erfahrungen mit TBM-Vortrieb bei hoher ÜberlagerungGEOMECHANICS AND TUNNELLING, Issue 5 2010Johann Brandl Mechanised tunnelling - Maschineller Vortrieb; Hydro power plants - Wasserkraftanlagen Abstract NTPC Ltd. of India is presently constructing the 520 MW (4 x 30 MW) Tapovan-Vishnugad hydroelectric power plant in Uttarakhand in the Himalayas. As part of this project, an approximately 12.1 km head race tunnel (HRT) is to be constructed, of which approximately 8.6 km are being excavated by DS-TBM with an excavation diameter of 6.575 m. Construction of this HRT has been awarded to a Joint Venture (JV) of Larsen, Toubro Ltd., India, and Alpine, Austria. Geoconsult ZT GmbH is acting as a Consultant to NTPC Ltd. for the TBM part of the HRT. The overburden above the tunnel is up to 1, 100 m with the result that knowledge of the geology along the HRT alignment could only be based on projections made from surface exposures available in the area. Basically, the ground consists of jointed quartzite, gneiss and schist. Excavation of the HRT started in October 2008 and excavation rates of over 500 m per month were achieved in November 2009. However, in December 2009 the TBM encountered a fault zone along with high-pressure water inflow and became trapped. This paper outlines the present status of HRT construction and describes in particular the difficulties encountered during TBM excavation in fault zones with large high-pressure water inflows and how these problems are being dealt with. Die indische Firma NTPC Ltd. errichtet derzeit das 520 MW (4 x 130 MW) Tapovan-Vishnugad Wasserkraftwerk in Uttarakhand, Himalaya. Als Teil dieses Projekts wird ein ungefähr 12,1 km langer Triebwasserstollen (TWS) errichtet, wobei rund 8,6 km davon mittels einer DS-TBM mit einem Ausbruchdurchmesser von 6.575 m aufgefahren werden. Der Bau dieses Triebwasserstollens wurde an die Arbeitsgemeinschaft Larsen, Toubro Ltd., Indien, und Alpine, Österreich vergeben. Geoconsult ZT GmbH fungiert als Berater von NTPC Ltd. für den TBM-Teil des TWS. Aufgrund der Überlagerung des Tunnels von bis zu 1,100 m konnte die Geologie entlang des Triebwasserstollens nur durch Projektion von vorhandenen Oberflächenaufschlüssen aus der Umgebung bestimmt werden. Das Gebirge besteht hauptsächlich aus geklüftetem Quarzit, Gneis und Schiefer. Der Ausbruch des TWS begann im Oktober 2008. Im November 2009 wurde eine Vortriebsgeschwindigkeit von über 500 m pro Monat erreicht. Im Dezember 2009 jedoch fuhr die TBM eine Störzone mit einem Hochdruckwassereinbruch an, wodurch die TBM stecken blieb. Dieser Artikel skizziert den derzeitigen Stand des TWS und legt besonderes Augenmerk auf die Schwierigkeiten beim Auffahren der Störzone inklusive Hochdruckwassereinbruch mit einer TBM. Darüber hinaus wird gezeigt, wie sich die auftretenden Probleme lösen lassen. [source] Practical use of the International Olympic Committee Medical Commission position stand on the female athlete triad: A case exampleINTERNATIONAL JOURNAL OF EATING DISORDERS, Issue 3 2006Roberta Trattner Sherman PhD Abstract The female athlete triad consists of the interrelated problems of disordered eating, amenorrhea, and osteoporosis, and it is believed to affect female athletes in all sports and at all levels of competition. Objective: The current article highlights the Position Stand on the Female Athlete Triad of the International Olympic Committee's Medical Commission (IOCMC). Method: The literature related to disordered eating, energy availability, amenorrhea, and bone loss in athletes is briefly reviewed. A hypothetical case is presented to illustrate some of the common issues and problems encountered when working with athletes affected by the triad, such as the effect of weight on performance in "thin" sports, coach involvement, sport participation by symptomatic athletes, and treatment resistance/motivation. Results: Strategies recommended by the position stand for managing those issues and problems are presented regarding the referral, evaluation, and treatment phases of the management process. Conclusion: Implications of the position stand are discussed in terms of the IOCMC's endorsement of the athlete's health being primary to her performance. © 2006 by Wiley Periodicals, Inc., Int J Eat Disord, 2006 [source] Aktueller Stand in der Vitiligo-Therapie , Evidenzbasierte LiteraturanalyseJOURNAL DER DEUTSCHEN DERMATOLOGISCHEN GESELLSCHAFT, Issue 6 2007Tobias Forschner First page of article [source] Biological Cycles of Mineral Elements in a Young Mixed Stand in Abandoned Mining SoilsJOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 9 2007Da-Lun Tian Abstract Phytoremediation as a sustainable and inexpensive technology based on the removal of pollutants from the environment by plants is becoming an increasingly important objective in plant research. In this study, biological cycles of five nutrient elements (N, P, K, Ca, and Mg) and eight heavy metal elements (Fe, Cu, Zn, Mn, Cd, Ni, Pb and Co) were examined in young paniculed goldraintree (Koelreuteria paniculata Laxm) and common elaeocarpus (Elaeocarpus decipens) mixed stands in an abandoned mining area. We found that after vegetation restoration in abandoned mining areas, the organic matter and concentrations of nutrient elements were significantly increased and the heavy metal elements were significantly decreased, the annual retention, uptake and return were 75.0, 115.4, and 40.3 kg/hm2 for nutrient elements, and 1 878.0, 3 231.0 and 1 353.0 g/hm2 for heavy metal elements, respectively, with the utilization coefficient, cycling coefficient and turnover rate of 0.92, 0.35 and 0.32 for nutrient elements, and 1.24, 0.42 and 1.92 for heavy metal elements, respectively. Our results suggested that the vegetation restoration in abandoned mining areas had significant effects in improving environmental conditions, enhancing soil available nutrients, and ensuring human health. [source] Lebensdauerabschätzung an Kunststoffrohren mittels Zeitstand-InnendruckversuchMATERIALWISSENSCHAFT UND WERKSTOFFTECHNIK, Issue 5 2007C. Berger lifetime prediction; plastic pipes; internal pressure creep test Abstract Die Lebensdauervorhersage an Kunststoffrohren basiert nach dem aktuellen Stand des technischen Regelwerkes hauptsächlich auf dem Zeitstand-Innendruckversuch. In diesem Versuch werden die Rohre bei definiertem Innendruck und erhöhten Temperaturen akzeleriert geprüft, und aufgrund des geltenden Arrheniusgesetzes erfolgt daraufhin eine Lebensdauerextrapolation der Messwerte. Lifetime Prediction of Plastic Pipes by means of Internal Pressure Creep Test The Lifetime Prediction of plastic pipes is based, according to the current set of relevant technical regulations, mainly on the Internal Creep Rupture Test. In this examination, the test for the pipes performed in an accelerated mode with a defined internal pressure and at increased temperatures. In compliance with the applicable Arrhenius rate law, an extrapolation of the measured values then takes place. [source] A Novel System for Spectral Analysis of Solar Radiation within a Mixed Beech-Spruce StandPLANT BIOLOGY, Issue 2 2002H. Reitmayer Abstract: A multi-sensor system is described, based on a 1024 channel diode array spectrometer, to measure spectral radiant flux density in the range of 380 nm to 850 nm, with a resolution of 0.8 nm in minimal 16 milliseconds integration time per sensor (noon, clear sky conditions). 264 space-integrating 4, sensors deployed in the canopies and 2 m above stand floor are sequentially connected to the spectrometer by means of 30-m long fibre optics. During low-level conditions (dawn, overcast sky) the system automatically lengthens the integration time of the spectrometer. About 3 sec per sensor, i.e., 13 min for the total of 264 sensors (worst case) are needed to collect spectral energy data, store them on hard disk and move the channel multiplexer to the next fibre optic position. The detection limit of quartz fibre sensors is 0.2 W/m2; precision and absolute error of radiant flux density are smaller than 3 % and 10 %, respectively. The system, operating since 1999, is derived from a 20-sensor pilot system developed for PAR measurements (PMMA fibre sensor, 400nm to 700 nm). Data achieved with the system serve to determine vertical profiles of wavelength dependent radiation extinction, with special respect to R/FR ratios and to develop a model of spectral radiation distribution in a mature forest stand, prerequisites for the computation of carbon gain of the stand and the evaluation of stand growth models. [source] Stand and Deliver: Private Property and the Politics of Global DispossessionPOLITICAL STUDIES, Issue 1 2006Stefan Andreasson Property rights necessarily generate violent, and oftentimes lethal, processes of dispossession. While liberal theorists from Locke to Hayek consider property rights as an essential and emancipatory component of human freedom, they fail to consider societal power asymmetries impeding the ability of property rights to protect the interests of the weak and marginalised. If property rights produce freedom and prosperity, they do so very selectively. More obvious is the ongoing historical process of already propertied classes making ,clever usurpation into an irrevocable right' by extending private property regimes along two key dimensions , type and space. Examining various uses of private property over time reveals processes whereby relatively basic notions of private property, enforced by a Weberian state at the local level in the early era of industrialisation, are extended to encompass new and sophisticated forms of property that are enforced globally via international institutions. Two contemporary empirical cases of using property rights are examined in this paper: land reform in Southern Africa (specifically Zimbabwe) and intellectual property rights. In this context of ongoing dispossession, further privatisation and commodification can only exacerbate contemporary problems of marginalisation and dispossession. [source] The Political Fallout of Taking a Stand: The President, Congress, and the Schiavo CasePRESIDENTIAL STUDIES QUARTERLY, Issue 3 2007DONALD P. HAIDER-MARKEL Federal government involvement in the case of terminally ill Terri Schiavo provides an interesting opportunity to explore the potential impact of specific institutional actions on public approval of those institutions. We analyze national survey data from the period of federal intervention and a poll conducted several months later. Our analyses, which account for time and exposure to political news, suggest that presidential and congressional actions in the case were associated with a decline in approval for the president and congressional leaders. Thus, the president and Congress can pay a political price when they take high-profile actions a significant majority of the public opposes. [source] High Numbers of Naked Amoebae in the Planktonic Waters of a Mangrove Stand in Southern Florida, USATHE JOURNAL OF EUKARYOTIC MICROBIOLOGY, Issue 3 2000ANDREW ROGERSON ABSTRACT. This is the first study to examine the abundance of naked amoebae in the water column of a mangrove stand. A total of 37 different morphotypes was noted and at least 13 of these are probably new species. Over a one-year sampling interval, amoebae averaged 35,400 cells liter,1 (range 2,000,104,000) by an indirect enrichment cultivation method. Densities in the upper end of this range arc the highest ever reported for any planktonic habitat. Variation between samples was related to the quantity of suspended aggregates (floes) in the water column emphasizing that amoebae are usually floc-associated. The study also showed that it is essential to disrupt floc material prior to withdrawing sample aliquots for the indirect counting method since several amoebae can occupy the interstices of aggregates. There is concern that indirect enumeration methods that require organisms to be cultured in the laboratory seriously underestimate the true count. A direct counting method using acridine orange staining and epifluorescence microscopy was attempted to assess the possible magnitude of the error associated with indirect counting. While this direct method had limitations, notably the difficulty of unambiguously differentiating between small amoebae and nanoflagellates, the results suggested that the indirect method gave estimates that were close to the true count (within a factor of two). Mangrove waters are rich in heterotrophic protozoa (,3 × 106 liter1) and while the heterotrophic flagellates are by far the dominant group, naked amoebae outnumber ciliates some 20-foid. The ecological consequences of high numbers of amoebae, particularly the common small forms less than 10 ,m in length, need to be examined for these important coastal sites. [source] Penile Rehabilitation after Radical Prostatectomy: Where Do We Stand and Where Are We Going?THE JOURNAL OF SEXUAL MEDICINE, Issue 4ii 2007FACS, Run Wang MD ABSTRACT Introduction., Postprostatectomy erectile dysfunction (ED) remains a serious quality-of-life issue. Recent advances in the understanding of the mechanism of postprostatectomy ED have stimulated great attention toward penile rehabilitation. Aim., This review presents and analyzes a contemporary series of the recent medical literature pertaining to penile rehabilitation therapy after radical prostatectomy (RP). Main Outcome Measures., The laboratory and clinical studies related to penile rehabilitation are analyzed. The validity of the methodology and the conclusion of the findings from each study are determined. Methods., The published and presented reports dealing with penile rehabilitation following RP in human and cavernous nerve injury in animal models are reviewed. Results., Exciting scientific discoveries have improved our understanding of postprostatectomy ED at the molecular level. The rationale for postprostatectomy penile rehabilitation appears to be logical according to animal studies. However, clinical studies have not consistently replicated the beneficial effects found in the laboratory studies. Currently available clinical studies are flawed due to short-term follow-up, small number of patients in the studies, studies with retrospective nature, or prospective studies without control. Rehabilitation programs are also facing a challenge with the compliance, which is critical for success for any rehabilitation program. At the present time, we do not have concrete evidence to recommend what, when, how long, and how often a particular penile rehabilitative therapy can be used effectively. Conclusions., Large prospective, multicentered, placebo-controlled trials with adequate follow-up are necessary to determine the cost-effective and therapeutic benefits of particular penile rehabilitative therapy or therapies in patients following the treatment of clinically localized prostate cancer. Until such evidence is available, it is difficult to recommend any particular penile rehabilitation program as a standard of practice. Wang R. Penile rehabilitation after radical prostatectomy: Where do we stand and where are we going? J Sex Med 2007;4:1085,1097. [source] Skin Cancer in Organ Transplant Recipients,Where Do We Stand Today?AMERICAN JOURNAL OF TRANSPLANTATION, Issue 11 2008C. Ulrich Skin cancers are the most frequent malignancies in organ transplant recipients (OTR), with 95% being nonmelanoma skin cancers (NMSC), especially squamous (SCC) and basal cell carcinomas. Most OTR with a first SCC subsequently develop multiple NMSC within 5 years, highlighting the concept of ,field cancerization', and are also at high risk for noncutaneous cancers. In order to reduce the tumor burden in these patients, their management requires an interdisciplinary approach including revision of immunosuppression, new dermatological treatments and adequate education about photoprotection in specialized dermatology clinics for OTR. Whereas surgery remains the gold-standard therapy for NMSC, noninvasive methods have shown promising results to treat superficial keratoses and subclinical lesions on large body areas. Although the threshold of skin cancer necessitating revision of immunosuppression is debated, this measure should be envisaged at the occurrence of the first SCC, or in case of multiple non-SCC NMSC. While the role of immunosuppressants in the occurrence of NMSC is widely recognized, the best immunosuppressive strategies remain to be defined. Presently, randomized prospective studies assess the burden of new skin tumors, as well as graft and patient survival, in patients with one or several NMSC after the introduction of mTOR (mammalian target of rapamycin) inhibitors. [source] A Place to Write: The Bartender as EthnographerANTHROPOLOGY & HUMANISM, Issue 2 2002Warren Olivo Julie Lindquist. A Place to Stand: Politics and Persuasion in. Working-Class Bar. New York: Oxford University Press, 2002. vii. 204 pp. [source] Population Density and Home Range Size of Red-Rumped Agoutis (Dasyprocta leporina) Within and Outside a Natural Brazil Nut Stand in Southeastern Amazonia,BIOTROPICA, Issue 2 2005Malu S. P. Jorge ABSTRACT This study examined whether the population density and home range size of red-rumped agoutis were affected by the spatial distribution of Brazil nut trees, at the Pinkaiti Research Station, in eastern Amazonia. Agouti densities in a Brazil nut grove were two-fold higher and home ranges were half the size than those outside it. This indicates that the large supply of Brazil nuts results in higher densities and smaller home ranges of agoutis in this seasonally dry Amazonian forest. RESUMEN Este estudo examinou a influência da distribuição espacial local de castanha-do-Pará na densidade populacional e a área de vida de cutias, na Estação de Pesquisas Pinkaiti, Amazônia Oriental. Densidade populacional de cutias dentro de um Castanhal foi o dobro e as áreas de vida metade daquelas observadas em área fora do Castanhal. Isto indica que a abundância local de castanha-do-Pará resulta em diferenças tanto na densidade quanto no tamanho da área de vida de cutias. [source] CHEMSAFE , Eine Datenbank für bewertete sicherheitstechnische KenngrößenCHEMIE-INGENIEUR-TECHNIK (CIT), Issue 1-2 2009M. Molnarne Dr.-Ing. Abstract Sicherheitstechnische Kenngrößen bilden die Grundlage des Brand- und Explosionsschutzes. Sie müssen daher stets auf dem neuesten Stand, verlässlich und schnell verfügbar sein. Diese Anforderungen erfüllt die Datenbank CHEMSAFE, ein Gemeinschaftsprojekt der Bundesanstalt für Materialforschung und -prüfung (BAM), der Physikalisch-Technischen Bundesanstalt (PTB) und der DECHEMA Gesellschaft für Chemische Technik und Biotechnologie e. V. Die Datenbank enthält von Fachleuten bewertete Kenngrößen von etwa 3000 brennbaren Flüssigkeiten, Gasen und Stäuben sowie von etwa 2800 Gemischen. [source] Extrusion zur Gestaltung von LebensmittelstrukturenCHEMIE-INGENIEUR-TECHNIK (CIT), Issue 8 2008P. Schuchmann Prof. Dr.-Ing.Article first published online: 29 JUL 200 Abstract Die Extrusion findet bei der Herstellung von konsumentengerechten Lebensmitteln immer weitere Verbreitung, da thermische und mechanische Grundoperationen mit Texturgebenden Prozessschritten in einer verfahrenstechnische Anlage verbunden werden können. Trotz zahlreicher Erkenntnisse aus dem Bereich der Kunststoffextrusion ist im Bereich der Lebensmittelverarbeitung das zur gezielten Produktgestaltung benötigte Prozessverständnis zurzeit noch nicht ausreichend. Dieser Übersichtsbeitrag fasst den Stand des Wissens zusammen und zeigt aktuelle Forschungsansätze. [source] Grassland communities on a Sahelian peneplain in Burkina FasoFEDDES REPERTORIUM, Issue 1-2 2008J. V. Müller Dr. A detailed phytosociological analysis of grassland communities of a Sahelian peneplain in Burkina Faso (West Africa) is presented. The floristic structure of the vegetation was documented with 113 relevés, which were classified manually and in addition ordinated to characterize main floristic gradients. The topographical situation from high-lying areas of the peneplain with erosion of material to low-lying areas with accumulation of material turned out to be the most important differentiating factor in the data set. All grassland communities are dominated by annual grasses and have large distribution ranges. They colonize sandy-silty, loamy to clayey soils and can be water-saturated or repeatedly inundated during the rainy season, while dry, non-inundated habitats are also colonized. Many grasses are valuable fodder plants and are appreciated by livestock , the peneplain is economically highly important as a grazing ground. Whereas exozoochorous annual species are constantly present companions, perennial herbaceous species are almost completely missing. Stands were grouped into one alliance Panico laeti-Echinochloion colonae and only two phytocoenoses: a rankless Schoenefeldia gracilis -community (with two subcommunities: a typical subcommunity with a large ecological amplitude from sandy-silty to loamy soils, and an Aristida funiculata -subcommunity on sandy, dry, non-inundated soils) and Eragrostietum pilosae. The Eragrostietum pilosae grows in the low-lying areas of the peneplain and connects between communities of seasonally inundated lakes and the grasslands on the upper parts of the pene- plain. Following the topography, the two plant communities form a large transition (zonation complex). It is widespread across the study area and contains the diagnostic species of both plant communities. The plant communities are compared with other Sahelian grass-dominated plant communities, and with plant communities from the Sahara and the (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) Grasfluren einer sahelischen Rumpffläche in Burkina Faso In diesem Beitrag wird eine detaillierte pflanzensoziologische Analyse der Grasfluren einer sahelischen Rumpffläche in Burkina Faso (Westafrika) präsentiert. Die floristische Struktur der Vegetation wurde mit 113 pflanzensoziologischen Aufnahmen dokumentiert. Diese wurden zunächst manuell klassifiziert und anschließend einem Ordinationsverfahren unterzogen, um die wichtigsten Gradienten im floristischen Datensatz aufzuzeigen. Die topographische Geländesituation der Rumpffläche, beginnend mit hochgelegenen Bereichen mit Materialaustrag bis in die Niederungen mit Materialeintrag, wurde als wichtigster differenzierender Faktor des floristischen Datensatzes identifiziert. Alle untersuchten Pflanzengesellschaften der Grasfluren haben große Verbreitungsgebiete und werden von annuellen Gräsern dominiert. Sie sind auf sandig-schluffigen, lehmigen bis tonigen Böden zu finden. Sie können in der Regenzeit entweder wassergesättigt oder wiederholt überflutet sein. Die Grasfluren sind auch auf trockenen, nicht überfluteten Standorten nachgewiesen. Viele der Grasarten sind vom Weidevieh geschätzte Futterpflanzen , die Rumpffläche dient als wirtschaftlich bedeutendes Weideland. Exozoochore, einjährige Arten sind hochstet als Begleiter vorhanden. Hingegen fehlen mehrjährige, krautige Arten fast vollständig. Die Bestände konnten einem pflanzensoziologischen Verband Panico laeti-Echinochloion colonae und zwei Pflanzengesellschaften zugeordnet werden. Die ranglose Schoenefeldia gracilis -Gesellschaft kommt in zwei Untereinheiten vor: eine typische Untereinheit mit breiter ökologischer Amplitude von sandig-schluffigen bis lehmigen Böden, und eine Aristida funiculata Untereinheit auf trockenen, sandigen, nicht überfluteten Böden. Das Eragrostietum pilosae kommt in den tiefliegenden Bereichen Sudanian zone. A close floristic relationship of Sahelian grassland communities with Saharan vegetation could be shown. der Rumpffläche vor und vermittelt zwischen den Pflanzengesellschaften temporärer Seen und den Grasfluren der hochgelegenen Bereiche der Rumpffläche. Der Geländesituation folgend bilden beide Pflanzengesellschaften einen breiten Übergangsbereich (Zonationskomplex). Dieser Übergangsbereich ist im Untersuchungsgebiet weit verbreitet und enthält diagnostische Arten beider Pflanzengesellschaften. Die beschriebenen Einheiten werden mit anderen grasdominierten Pflanzengesellschaften des Sahels sowie der Sahara und der Sudanzone verglichen. Eine enge floristische Beziehung der sahelischen Grasfluren mit Vegetationseinheiten der Sahara wird aufgezeigt. [source] Epidemiology of Heterobasidion abietinum and Viscum album on silver fir (Abies alba) stands of the PyreneesFOREST PATHOLOGY, Issue 1 2010J. Oliva Summary In the last two decades, stand decline and increased mortality has affected silver fir (Abies alba) forests in the Spanish Pyrenees. Simultaneously severe occurrences of the root rot fungus Heterobasidion annosum s.l. and of the mistletoe Viscum album have been reported. We aimed to improve the understanding of the epidemiology of both pathogens in our region. All H. annosum isolates found on silver fir were typed as H. abietinum. H. abietinum was more frequently observed where cuttings had targeted fir trees rather than other species. H. abietinum fruiting bodies were observed in the most recently cut stumps. V. album was more abundant on more dominant fir trees, and in southern aspect stands. The number of V. album colonies in the stand correlated (R2 = 0.40) with silver fir mortality. Stands with a high level of V. album infection tended to have a smaller percentage of basal area in species other than silver fir, and they tended to be located on more south-facing slopes. H. abietinum was widespread in silver fir forests of the Pyrenees. Our data suggest that, in the Pyrenees, the observed H. abietinum incidence may represent a combination of both primary and secondary spread of the pathogen. Favouring mixed forests should be tested as a potential control method for V. album. The correlation between silver fir mortality and V. album infection warrants further study, as the observed tree mortality could have occurred due to other factors than V. album, such as drought damage. [source] Fungi associated with a natural epizootic in Fiorinia externa Ferris (Hemiptera: Diaspididae) populationsJOURNAL OF APPLIED ENTOMOLOGY, Issue 2 2009J. A. P. Marcelino Abstract Stands of eastern hemlock [(Tsuga canadensis (L.) Carrière] in the northeastern United States are in decline, in part from the attack of elongate hemlock scale, Fiorinia externa Ferris (Hemiptera: Diaspididae). From 2001 to the present, a natural epizootic has been observed in populations of F. externa. Initially discovered at the Mianus River Gorge Preserve in Bedford, New York, the epizootic has also been detected in Pennsylvania, New Jersey and Connecticut. Understanding and assessing the identity of the pathogenic micro-organisms responsible for this natural mortality is crucial for developing biological controls for this pest. We have isolated and taxonomically and genetically identified entomopathogens, phytopathogens and endophytic fungi associated with F. externa. Isolates of the following were obtained: Colletotrichum sp., Lecanicillium lecanii, Beauveria bassiana, Metarhiziopsis microspora, Myriangium sp., Mycosphaerella sp. anamorph, Nectria sp., Botrytis sp., Phialophora sp. and Fusarium sp. [source] Californian mixed-conifer forests under unmanaged fire regimes in the Sierra San Pedro Mártir, Baja California, MexicoJOURNAL OF BIOGEOGRAPHY, Issue 1 2000R. A. Minnich Abstract Aim,This study appraises historical fire regimes for Californian mixed-conifer forests of the Sierra San Pedro Mártir (SSPM). The SSPM represents the last remaining mixed-conifer forest along the Pacific coast still subject to uncontrolled, periodic ground fire. Location,The SSPM is a north,south trending fault bound range, centred on 31°N latitude, 100 km SE of Ensenada, Baja California. Methods,We surveyed forests for composition, population structure, and historical dynamics both spatially and temporally over the past 65 years using repeat aerial photographs and ground sampling. Fire perimeter history was reconstructed based on time-series aerial photographs dating from 1942 to 1991 and interpretable back to 1925. A total of 256 1-ha sites randomly selected from aerial photographs were examined along a chronosequence for density and cover of canopy trees, density of snags and downed logs, and cover of non-conifer trees and shrubs. Twenty-four stands were sampled on-the-ground by a point-centred quarter method which yielded data on tree density, basal area, frequency, importance value, and shrub and herb cover. Results,Forests experience moderately intense understory fires that range in size to 6400 ha, as well as numerous smaller, low intensity burns with low cumulative spatial extent. SSPM forests average 25,45% cover and 65,145 trees per ha. Sapling densities were two to three times that of overstory trees. Size-age distributions of trees , 4 cm dbh indicate multi-age stands with steady-state dynamics. Stands are similar to Californian mixed conifer forests prior to the imposition of fire suppression policy. Livestock grazing does not appear to be suppressing conifer regeneration. Main conclusions,Our spatially-based reconstruction shows the open forest structure in SSPM to be a product of infrequent, intense surface fires with fire rotation periods of 52 years, rather than frequent, low intensity fires at intervals of 4,20 years proposed from California fire-scar dendrochronology (FSD) studies. Ground fires in SSPM were intense enough to kill pole-size trees and a significant number of overstory trees. We attribute long fire intervals to the gradual build-up of subcontinuous shrub cover, conifer recruitment and litter accumulation. Differences from photo interpretation and FSD estimates are due to assumptions made with respect to site-based (point) sampling of fire, and nonfractal fire intensities along fire size frequency distributions. Fire return intervals determined by FSD give undue importance to local burns which collectively use up little fuel, cover little area, and have little demographic impact on forests. [source] The relative importance of dispersal limitation of vascular plants in secondary forest succession in Muizen Forest, BelgiumJOURNAL OF ECOLOGY, Issue 5 2001Kris Verheyen Abstract 1,Distribution patterns (frequency and percentage cover) of 18 forest plant species were studied in 34 ha of mixed deciduous forest (Muizen Forest, north Belgium). Stands varied in age between 6 and more than 223 years and both slow and fast colonizing species were studied. 2,Detailed land use history data were combined with the species distribution maps to identify species-specific colonization sources and calculate colonization distances. 3,A multiple logistic regression model was constructed with four covariables: pH (which can impose limits on the potential species-distribution), secondary forest age, distance from nearest colonization source and age,distance interaction, to allow us to account for the gradual completion of colonization over time. 4,We could distinguish species which are limited by both dispersal and recruitment (Primula elatior, Arum maculatum and Lamium galeobdolon), mainly by dispersal (Anemone nemorosa, Deschampsia cespitosa), mainly by recruitment (Paris quadrifolia and Polygonatum multiflorum) and by neither (Geum urbanum, Ranunculus ficaria, Glechoma hederacea, Aegopodium podagraria, Ajuga reptans, Adoxa moschatellina and Oxalis acetosella). 5,The low colonizing capacity of ancient forest plants cannot be attributed to a single cause; rather both dispersal and recruitment are limiting but the relative importance varies. [source] Effect of the stage of growth, wilting and inoculation in field pea (Pisum sativum L.) silages.JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 9 2006Abstract The stage of growth, field wilting and inoculation with lactic acid bacteria (LAB) effects were studied by ensiling herbage of field pea (Pisum sativum L.) at four consecutive stages. Stands of semi-leafless field pea, sown in spring, were harvested at four progressive morphological stages (end of flowering, I; beginning of pod filling, II; advanced pod filling, III; beginning of ripening, IV). For each stage of growth, the herbage was field wilted to a dry matter (DM) content of 318, 300, 348 and 360 g kg,1 for stages I, II, III and IV, respectively. The unwilted and wilted herbages were ensiled in 5-L silos, with (I) and without (C) a LAB inoculant (Lactobacillus plantarum). High levels of ethanol, lactic acid and volatile fatty acids (VFA) were observed in all silages, facilitated by the high levels of water-soluble carbohydrates (WSC) at ensiling (from 111 to 198 g kg,1 DM). Despite the low pH values (4.3 and 4.1 for C and I silages, respectively), all the silages showed detectable levels of butyric acid. Field peas can be successfully ensiled after a short wilting period with reduced field curing and reduce DM losses onward from advanced pod filling stage, with the aid of LAB inoculum. Copyright © 2006 Society of Chemical Industry [source] Fire disturbance and forest structure in old-growth mixed conifer forests in the northern Sierra Nevada, CaliforniaJOURNAL OF VEGETATION SCIENCE, Issue 6 2007R. Matthew Beaty Abstract Question: This study evaluates how fire regimes influence stand structure and dynamics in old-growth mixed conifer forests across a range of environmental settings. Location: A 2000-ha area of mixed conifer forest on the west shore of Lake Tahoe in the northern Sierra Nevada, California. Methods: We quantified the age, size, and spatial structure of trees in 12 mixed conifer stands distributed across major topographic gradients. Fire history was reconstructed in each stand using fire scar dendrochronology. The influence of fire on stand structure was assessed by comparing the fire history with the age, size, and spatial structure of trees in a stand. Results: There was significant variation in species composition among stands, but not in the size, age and spatial patterning of trees. Stands had multiple size and age classes with clusters of similar aged trees occurring at scales of 113 - 254 m2. The frequency and severity of fires was also similar, and stands burned with low to moderate severity in the dormant season on average every 9,17 years. Most fires were not synchronized among stands except in very dry years. No fires have burned since ca. 1880. Conclusions: Fire and forest structure interact to perpetuate similar stand characteristics across a range of environmental settings. Fire occurrence is controlled primarily by spatial variation in fuel mosaics (e.g. patterns of abundance, fuel moisture, forest structure), but regional drought synchronizes fire in some years. Fire exclusion over the last 120 years has caused compositional and structural shifts in these mixed conifer forests. [source] Change over 70 years in a southern California chaparral community related to fire historyJOURNAL OF VEGETATION SCIENCE, Issue 5 2004Janet Franklin Abstract: Question: What changes in species composition and cover have occurred in chaparral as a function of fire history across an ecoregion? Location: San Diego County, California, USA. Methods: Stands in which 40 mid-elevation chaparral vegetation plots (each 400 m2 in area) were located in the 1930s were resurveyed in 2001. We stratified the stands into Infrequently versus Frequently burned (0,1 versus 2 or more fires recorded in the 91-yr period), and Immature versus Mature (31 yr versus >31 yr since last fire), resulting in four groups. Ten stands were randomly selected from each of these groups for survey. Results: There were no major shifts in life form composition, e.g., live oak trees were not invading chaparral that had experienced little or no fire, nor were subshrubs or herbaceous species replacing shrubs in areas that had experienced more frequent fires. However, there was a notable increase in the frequency of the subshrub Eriogonum fasciculatum across all fire history groups. In the mature stands with infrequent fire, average cover of resprouting shrubs increased (from 72 to 91%) and cover of obligate seeding shrubs (species with fire-cued germination) decreased (from 21 to 6%) significantly. Mature stands with frequent fire showed a significant decrease in resprouter cover (from 87 to 80%) and increase in obligate seeders (from 10 to 16%). Conclusions: While the tremendous changes in land use in southern California have been predicted to cause shifts in chaparral composition, these shifts are difficult to detect because species longevity and fire cycles are on the order of decades to a century. In this study, the expected trends could only be detected in groups that were mature at the time of the second survey. [source] Effects of elevated CO2, drought and temperature on the water relations and gas exchange of groundnut (Arachis hypogaea) stands grown in controlled environment glasshousesPHYSIOLOGIA PLANTARUM, Issue 1 2000Sean C. Clifford Stands of groundnut (Arachis hypogaea L. cv. Kadiri-3) were grown in controlled environment glasshouses at mean atmospheric CO2 concentrations of 375 or 700 ,mol mol,1 and daily mean air temperatures of 28 or 32°C on irrigated or drying soil profiles. Leaf water (,l) and solute potential (,s), relative water content (RWC), stomatal conductance (gl) and net photosynthesis (Pn) were measured at midday for the youngest mature leaf throughout the growing season. Elevated CO2 and temperature had no detectable effect on the water relations of irrigated plants, but higher values of RWC, ,l and ,s were maintained for longer under elevated CO2 during progressive drought. Turgor potential (,p) reached zero when ,l declined to ,1.6 to ,1.8 MPa in all treatments; turgor was lost sooner when droughted plants were grown under ambient CO2. A 4°C increase in mean air temperature had no effect on ,s in droughted plants, but elicited a small increase in ,l; midday gl values were lower under elevated than under ambient CO2, and ,l and gl declined below ,1.5 MPa and 0.25 cm s,1, respectively, as the soil dried. Despite the low gl values recorded for droughted plants late in the season, Pn was maintained under elevated CO2, but declined to zero 3 weeks before final harvest under ambient CO2. Concurrent reductions in gl and increases in water use efficiency under elevated CO2 prolonged photosynthetic activity during drought and increased pod yields relative to plants grown under ambient CO2. The implications of future increases in atmospheric CO2 for the productivity of indeterminate C3 crops grown in rainfed subsistence agricultural systems in the semi-arid tropics are discussed. [source] Density-Induced Plant Size Reduction and Size Inequalities in Ethylene-Sensing and Ethylene-Insensitive TobaccoPLANT BIOLOGY, Issue 2 2004R. Pierik Abstract: Plant competition for light is a commonly occurring phenomenon in natural and agricultural vegetations. It is typically size-asymmetric, meaning that slightly larger individuals receive a disproportionate share of the light, leaving a limited amount of light for the initially smaller individuals. As a result, size inequalities of such stands increase with competition intensity. A plant's ability to respond morphologically to the presence of neighbour plants with enhanced shoot elongation, the so-called shade avoidance response, acts against the development of size inequalities. This has been shown experimentally with transgenic plants that cannot sense neighbours and, therefore, show no shade avoidance responses. Stands of such transgenic plants showed a much stronger development of size inequalities at high plant densities than did wild type (WT) stands. However, the transgenic plants used in these experiments displayed severely hampered growth rates and virtually no response to neighbours. In order to more precisely study the impact of this phenotypic plasticity on size inequality development, experiments required plants that have normal growth rates and reduced, but not absent, shade avoidance responses. We made use of an ethylene-insensitive, transgenic tobacco genotype (Tetr) that has wild type growth rates and moderately reduced shade avoidance responses to neighbours. Here, we show that the development of size inequalities in monocultures of these plants is not affected unambiguously different from wild type monocultures. Plots of Tetr plants developed higher inequalities for stem length than did WT, but monocultures of the two genotypes had identical CV (Coefficient of Variance) values for shoot biomass that increased with plant density. Therefore, even though reduced shade avoidance capacities led to the expected higher size inequalities for stem length, this does not necessarily lead to increased size inequalities for shoot biomass. [source] Habitat Overlap and Facilitation in Tamarisk and Box Elder Stands: Implications for Tamarisk Control Using Native PlantsRESTORATION ECOLOGY, Issue 3 2010John M. DeWine Invasive plants are typically managed using top-down control techniques that focus on the removal of the target organism. Bottom-up control limits the resources available to the undesired species by manipulating disturbance, competition, and successional processes, and thus may prevent reinvasion. Tamarisk species (Tamarix sp.) have invaded riparian areas throughout western North America, resulting in expansive control efforts. A companion study has shown that a native competitor, Box elder (Acer negundo), is capable of outcompeting and killing established Tamarisk through light interception in canyons of Dinosaur National Monument (DNM), Colorado. The goal of this study was to determine the feasibility of using Box elder as a bottom-up control agent by (1) determining the distributional overlap of the two species in DNM; (2) determining if Tamarisk facilitates Box elder establishment; and (3) analyzing Box elder seedling survival across a range of physical gradients. The distribution of Tamarisk and Box elder overlapped considerably throughout the study area. Box elder seedlings were planted under Tamarisk canopies or areas with the canopy removed. Survival was significantly higher under Tamarisk canopies, indicating that Tamarisk facilitates Box elder seedling survival. Box elder seedling survival was tested across soil texture, litter depth, groundwater depth, and shade intensities indicative of conditions found in the canyons of DNM, and survival was high for all treatments. The manipulation of competitive and successional processes through the promotion of Box elder and other native tree establishment is suggested as a means of bottom-up Tamarisk control to complement traditional control techniques. [source] | |||||||||||||||||||||||||||||||||||||||||||||||||||||||