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Agriculture of crops provides more than 85% of the energy in human diet, while also securing income of more than 2.6 billion people. To investigate past, present and future changes in the domain of food security, water resources and water use, nutrient cycles, and land management it is required to know the agricultural land use, in particular which crop grows where and when. The current global land use or land cover data sets are based on remote sensing and agricultural census statistics. In general, these only contain one or very few classes of agricultural land use. When crop-specific areas are given, no distinction of irrigated and rainfed areas is made, whereas it is necessary to distinguish rainfed and irrigated crops, because crop productivity and water use differ significantly between them.
To support global-scale assessments that are sensitive to agricultural land use, the global data set of Monthly Irrigated and Rainfed Crop Areas around the year 2000 (MIRCA2000) was developed by the author. With a spatial resolution of 5 arc-minutes (approximately 9.2 km at the equator), MIRCA2000 provides for the first time, spatially explicit irrigated and rainfed crop areas separately for each of the 26 crop classes for each month of the year, and includes multi-cropping. The data set covers all major food crops as well as cotton, while the remaining crops are grouped into three categories (perennial, annual and fodder grasses). Also for the first time, crop calendars on national or sub-national level were consistently linked to annual values of harvested area at the 5 arc-minutes grid cell level, such that monthly growing areas could be computed that are representative for the time period 1998 to 2002.
The downscaling algorithm maximizes the consistency to the grid-based input data of cropland extent [Ramankutty et al., 2008], crop-specific total annual harvested area [Monfreda et al., 2008], and area equipped for irrigation [Siebert et al., 2007]. In addition to the methodology, this dissertation describes differences to other datasets and standard scaling methods, as well as some applications. For quality assessment independent datasets and newly developed quality parameters are used, and scale effects are discussed.
Supplementary Appendices document crop calendars for irrigated and rainfed crops for each of the 402 spatial units (Appendix I), data sources of harvested area and of cropping periods for irrigated crops, country by country (Appendix K), as well as data quality parameters (Appendix L, including spreadsheet files).
Einleitung:
Wahrscheinlich hat es seit den 1970er Jahren nicht mehr so viele kritische Initiativen von Geographiestudierenden an Hochschulen in deutschsprachigen Ländern gegeben wie heute. Ihre Aktivitäten reichen von Lesekreisen, Tutorien, Exkursionen, Film- und Vortragsreihen bis zu politischen Aktionen, wobei viele Initiativen über den Arbeitskreis (AK) Kritische Geographie vernetzt sind. Parallel zu dieser erfreulichen Beobachtung findet ein fundamentaler Umbau der Hochschule statt. Die zunehmende Ökonomisierung des Studiums durch den Bologna-Prozess birgt die Gefahr, Gesellschaftskritik auf dem Altar der Verwertbarkeit und der "Praxisrelevanz" zu opfern. Diese Entwicklungen geben Anlass, das Verhältnis zwischen der Arbeit kritischer Initiativen und den reformierten Universitäten kritisch zu hinterfragen und damit den Zusammenhang zwischen Bologna-Prozess, Neoliberalisierung und kritischer Wissenschaft für die geographische Hochschullehre aus einer studentischen Perspektive zu beleuchten, wird doch ein nicht unbedeutender Teil der kritischen Geographie von Studierenden getragen.
Im Folgenden werden wir kurz auf den Bologna-Prozess eingehen, anschließend die Fragestellung und das methodische Vorgehen erläutern, um darauf aufbauend die empirischen Ergebnisse vorzustellen und zu diskutieren.
Droplets produced in a cloud condensation nuclei chamber (CCNC) as a function of supersaturation have been separated from unactivated aerosol particles using counterflow virtual impaction. Residual material after droplets were evaporated was chemically analyzed with an Aerodyne Aerosol Mass Spectrometer (AMS) and the Particle Analysis by Laser Mass Spectrometry (PALMS) instrument. Experiments were initially conducted to verify activation conditions for monodisperse ammonium sulfate particles and to determine the resulting droplet size distribution as a function of supersaturation. Based on the observed droplet size, the counterflow virtual impactor cut-size was set to differentiate droplets from unactivated interstitial particles. Validation experiments were then performed to verify that only droplets with sufficient size passed through the counterflow virtual impactor for subsequent analysis. A two-component external mixture of monodisperse particles was also exposed to a supersaturation which would activate one of the types (hygroscopic salts) but not the other (polystyrene latex spheres or adipic acid). The mass spectrum observed after separation indicated only the former, validating separation of droplets from unactivated particles. Results from ambient measurements using this technique and AMS analysis were inconclusive, showing little chemical differentiation between ambient aerosol and activated droplet residuals, largely due to low signal levels. When employing as single particle mass spectrometer for compositional analysis, however, we observed enhancement of sulfate in droplet residuals.
Droplets produced in a cloud condensation nucleus chamber as a function of supersaturation have been separated from unactivated aerosol particles using counterflow virtual impaction. Residual material after droplets were evaporated was chemically analyzed with an Aerodyne Aerosol Mass Spectrometer and the Particle Analysis by Laser Mass Spectrometry instrument. Experiments were initially conducted to verify activation conditions for monodisperse ammonium sulfate particles and to determine the resulting droplet size distribution as a function of supersaturation. Based on the observed droplet size, the counterflow virtual impactor cut-size was set to differentiate droplets from unactivated interstitial particles. Validation experiments were then performed to verify that only droplets with sufficient size passed through the counterflow virtual impactor for subsequent analysis. A two-component external mixture of monodisperse particles was also exposed to a supersaturation which would activate one of the types (ammonium sulfate) but not the other (polystyrene latex spheres). The mass spectrum observed after separation indicated only the former, validating separation of droplets from unactivated particles. Results from atmospheric measurements using this technique indicate that aerosol particles often activate predominantly as a function of particle size. Chemical composition is not irrelevant, however, and we observed enhancement of sulfate in droplet residuals using single particle analysis.
The performance of an ion source based on corona discharge has been studied. This source is used for the detection of gaseous sulfuric acid by chemical ionization mass spectrometry (CIMS) through the reaction of NO−3 ions with H2SO4. The ion source is operated under atmospheric pressure and its design is similar to the one of a radioactive (americium-241) ion source which has been used previously. The results show that the detection limit for the corona ion source is sufficiently good for most applications. For an integration time of 1 min it is ~6×104 molecule cm−3 of H2SO4. In addition, only a small cross-sensitivity to SO2 has been observed for concentrations as high as 1 ppmv in the sample gas. This low sensitivity to SO2 is achieved even without the addition of an OH scavenger. When comparing the new corona ion source with the americium ion source for the same provided H2SO4 concentration, both ion sources yield almost identical values. These features make the corona ion source investigated here favorable over the more commonly used radioactive ion sources for most applications where H2SO4 is measured by CIMS.
The performance of an ion source based on corona discharge has been studied. This source is used for the detection of gaseous sulfuric acid by chemical ionization mass spectrometry (CIMS) through the reaction of NO3– ions with H2SO4. The ion source is operated under atmospheric pressure and its design is similar to the one of a radioactive (Americium 241) ion source which has been used previously. Our results show that the detection limit for the corona ion source is sufficiently good for most applications. For an integration time of one minute it is ~6 × 104 molecules of H2SO4 per cm3. In addition, only a small cross-sensitivity to SO2 has been observed for concentrations as high as 1 ppmv in the sample gas. This low sensitivity to SO2 is achieved even without the addition of an OH scavenger. When comparing the new corona ion source with the americium ion source for the same provided H2SO4 concentration, both ion sources yield almost identical values. These features make the corona ion source investigated here favorable over the more commonly used radioactive ion sources for most applications where H2SO4 is measured by CIMS.
It has been estimated that about 1% of live births carry severe congenital heart defects and 20-30% among them have valve malformations. Despite its medical importance the underlying cause of many valvular diseases remains undiscovered. Thus, it is important to identify genes that play a crucial role in cardiac valve formation and maturation.
A temporal RNA expression analysis of heart development suggested that the extracellular matrix protein Nephronectin might be a novel regulator of valve development and/or trabeculation. Nephronectin is transiently expressed during rat heart development at the time of heart valve morphogenesis and trabeculation. Moreover, the extracellular matrix is known to be crucial for organogenesis. It is a complex, dynamic and critical component that regulates cell behavior by modulating the activity, bioavailability, or presentation of growth factors to cell surface receptors.
In order to verify the hypothesis that Nephronectin is a novel regulator of valve formation and/or trabeculation the zebrafish was chosen as model system. Females are able to spawn at intervals of 5 days laying hundreds of eggs in each clutch. Development progresses rapidly with precursors to all major organs appearing within 36 hours post fertilization. Zebrafish embryos develop externally, are translucent and continue to grow for several days despite developing severely malformed, non functional hearts. In addition, gene expression can be easily modulated. During the present study it has been shown that Nephronectin expression is correlated to valve development and trabeculation. Morpholinomediated knockdown of Nephronectin in zebrafish caused failure of valve formation and trabeculation resulting in > 85% lethality at 7 days post fertilization.
Cardiac valve formation is initiated at the junction of atrium and ventricle and is characterized by extracellular matrix deposition and endocardial cell differentiation. In accordance with the above-described phenotype the earliest observed abnormality in Nephronectin morphants was an extended tube like structure at the atrio-ventricular boundary. In addition, the expression of myocardial genes involved in cardiac valve formation (cspg2, fibulin1, tbx2b, bmp4) was expanded and endocardial cells along the extended tube like structure exhibited characteristics of atrio-ventricular cells (has2, notch1b and Alcam expression, cuboidal cell shape). Inhibition of has2 in Nephronectin morphants rescued the endocardial but not the myocardial expansion. In contrast, diminishment of BMP signaling in npnt morphants resulted in reduced ectopic expression of myocardial and endocardial atrio-ventricular markers. Taken together, these results identify Nephronectin as a novel upstream regulator of BMP4-HAS2 signaling playing a crucial role in atrio-ventricular canal differentiation.
Vor Ihnen liegt unser zweites Open Journal of Knowledge Management der Community of Knowledge in diesem Jahr. Werden in dem jeweils ersten Open Journal of Knowledge Management des Jahres ausschließlich in einem Call for Papers eingereichte Beiträge publiziert, so handelt es sich bei dem zweiten um ein Review. In dem vorliegenden Journal finden Sie daher besonders erfolgreiche Beiträge der letzten 12 Monate, eine Art "Best of" der Community of Knowledge. Maßstab ist das Nutzerverhalten, also hauptsächlich die Seitenaufrufe, ergänzend die Verweildauer und Absprungrate. ...
Editorial Prodigal Italy Greece Spain? Events 01
DB Prize 2011: Award Ceremony in honor of Kenneth Rogoff 02
DB Prize 2011: CFS Symposium in honor of Kenneth Rogoff 03
Is the Euro Zone on its Way to Fiscal Union? 04
CFS Visitors Program - Pistaferri 05
Krugman’s Perspective on the Crisis 06
IMF Post-Annual Meetings Policy Discussion 07
International Conference on Payout Policy – Foundations and Trends 08
MONFISPOL – Final conference 09
CFS - EIEF Conference on Household Finance
Der Kontrollbegriff des WpÜG
(2011)
Die Bestimmungen des WpÜG über Übernahme- und Pflichtangebote knüpfen von jeher an das Halten von mindestens 30 Prozent der Stimmrechte einer Zielgesellschaft an. Der folgende Beitrag geht der Frage nach, ob dieser formale Kontrollbegriff des geltenden Rechts den Machtverhältnissen in börsennotierten Gesellschaften angemessen Rechnung trägt. Darüber hinaus hinterfragt er die systematische Stimmigkeit der unterschiedlichen Schwellenwerte für Kontrolle und Beherrschungsvermutung bei börsennotierten Gesellschaften.