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Search Results: 1 - 10 of 151475 matches for " H. Berger "
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On the Milankovitch sensitivity of the Quaternary deep-sea record
W. H. Berger
Climate of the Past Discussions , 2013, DOI: 10.5194/cpd-9-1237-2013
Abstract: The response of the climate system to external forcing has become an item of prime interest in the context of global warming, especially with respect to the rate of melting land-based ice masses. The deep-sea record of ice-age climate change has been useful in assessing the sensitivity of the climate system to such forcing, notably to orbital forcing, which is well-known for the last several million years. When comparing response and forcing, one finds that sensitivity varies greatly through time, apparently in dependence on the state of the system. The changing stability of ice masses presumably is the underlying cause for the changing state of the system. A buildup of vulnerable ice masses within the latest Tertiary, when going into the ice ages, is conjectured to cause a stepwise increase of climate variability since the early Pliocene.
Spatial heterogeneity of satellite derived land surface parameters and energy flux densities for LITFASS-area
A. Tittebrand,F. H. Berger
Atmospheric Chemistry and Physics (ACP) & Discussions (ACPD) , 2009,
Abstract: Based on satellite data in different temporal and spatial resolution, the current use of frequency distribution functions (PDF) for surface parameters and energy fluxes is one of the most promising ways to describe subgrid heterogeneity of a landscape. Objective of this study is to find typical distribution patterns of parameters (albedo, NDVI) for the determination of the actual latent heat flux (L.E) determined from highly resolved satellite data within pixel on coarser scale. Landsat ETM+, Terra MODIS and NOAA-AVHRR surface temperature and spectral reflectance were used to infer further surface parameters and radiant- and energy flux densities for LITFASS-area, a 20×20 km2 heterogeneous area in Eastern Germany, mainly characterised by the land use types forest, crop, grass and water. Based on the Penman-Monteith-approach L.E, as key quantity of the hydrological cycle, is determined for each sensor in the accordant spatial resolution with an improved parametrisation. However, using three sensors, significant discrepancies between the inferred parameters can cause flux distinctions resultant from differences of the sensor filter response functions or atmospheric correction methods. The approximation of MODIS- and AVHRR- derived surface parameters to the reference parameters of ETM (via regression lines and histogram stretching, respectively), further the use of accurate land use classifications (CORINE and a new Landsat-classification), and a consistent parametrisation for the three sensors were realized to obtain a uniform base for investigations of the spatial variability. The analyses for 4 scenes in 2002 and 2003 showed that for forest clear distribution-patterns for NDVI and albedo are found. Grass and crop distributions show higher variability and differ significantly to each other in NDVI but only marginal in albedo. Regarding NDVI-distribution functions NDVI was found to be the key variable for L.E-determination.
Spatial heterogeneity of satellite derived land surface parameters and energy flux densities for LITFASS-area
A. Tittebrand,F. H. Berger
Atmospheric Chemistry and Physics Discussions , 2008,
Abstract: Remote sensing data provide area integrated information of surface properties in different spatial or temporal resolutions according to different sensor features. Landsat ETM+, Terra MODIS and NOAA-AVHRR surface temperature and spectral reflectance were used to infer further surface parameters and radiant- and energy flux densities for LITFASS-area, a 20×20 km2 heterogeneous area in Eastern Germany, mainly characterized by the land use types forest, crop, grass and water. Based on the Penman-Monteith-approach the actual latent heat flux (L.E), as key quantity of the hydrological cycle, is determined for each sensor in the accordant spatial resolution with an improved parametrization. However, using three sensors, significant discrepancies between the inferred parameters can cause flux distinctions resultant from differences of the sensor filter response functions or atmospheric correction methods. The approximation of MODIS- and AVHRR- derived surface parameters to the reference parameters of ETM (via regression lines and histogram stretching, respectively), further the use of accurate land use classifications (CORINE and a new Landsat-classification), and a consistent parametrization for the three sensors were realized to obtain a uniform base for investigations of the spatial variability. For the target area the spatial heterogeneity is analysed investigating frequency distribution functions (PDF) for surface parameters and energy fluxes. PDF is the most promising way to describe subgrid heterogeneity due to the given data in different spatial resolution. Aim of this study is to find typical distribution pattern of parameters (albedo, NDVI) for the determination of L.E determined from the highly resolved ETM data within pixel on coarser scale (MODIS, AVHRR). The analyses for 4 scenes in 2002 and 2003 showed that clear distribution-pattern for forest for NDVI and albedo are found. Grass and crop distributions show higher variability and differ significantly to each other in NDVI but only marginal in albedo. Regarding NDVI-distribution functions NDVI was found to be the key variable for L.E-determination.
Kinderwunsch Online Coaching - ein webbasiertes Selbsthilfeprogramm
H?mmerli K,Znoj H,Berger T
Journal für Reproduktionsmedizin und Endokrinologie , 2009,
Abstract: Immer mehr Paare bleiben ungewollt kinderlos. Obschon sich infertile Patienten generell bezüglich psychopathologischer Auff lligkeiten nicht von der Allgemeinbev lkerung unterscheiden, stellt die Zeit des Bangens und Hoffens auf ein Kind, die Behandlung und die Verarbeitung der Kinderlosigkeit eines der stressreichsten Lebensereignisse dar. Insbesondere w hrend der reproduktionsmedizinischen Behandlung wurden kurzfristig erh hte Werte in Depressivit t und ngstlichkeit bei infertilen Frauen best tigt. Da oftmals psychologische Unterstützung fehlt und ein offener Umgang mit Infertilit t für die Paare h ufig schwierig ist, sucht eine Vielzahl infertiler Patienten aus dem Internet Informationen und Austausch heute existieren unz hlige Informationsseiten und Selbsthilfeforen zu Infertilit t. Gleichzeitig besteht ein Mangel an empirisch und theoretisch fundierten psychologischen Unterstützungsans tzen. In diesem Beitrag wird das erste deutschsprachige webbasierte Selbsthilfebehandlungsprogramm für infertile Patienten vorgestellt. Erfahrungen einer ersten Evaluation des Programms werden diskutiert.
The Crucial Role of Bilateral Infraclavicular Nerve Blocks in the Anesthetic Management of a Trauma Patient  [PDF]
Eric P. Chiang, Paul Dangerfield, Jaideep H. Mehta, Marian Sherman, Jeffrey S. Berger
Open Journal of Anesthesiology (OJAnes) , 2012, DOI: 10.4236/ojanes.2012.24026
Abstract: Bilateral brachial plexus blocks and regional anesthesia in trauma patients are rarely performed due to potential complications when using these techniques. We illustrate a case in which bilateral infraclavicular nerve blocks were placed as part of a multimodal approach to pain management in a trauma patient. We discuss potential hazards, important considerations, and rationale for attempting this procedure. Ultimately, performing bilateral brachial plexus nerve blocks in trauma patients is a viable option when choosing pain management techniques.
Characterisation of methionine adenosyltransferase from Mycobacterium smegmatis and M. tuberculosis
Bradley J Berger, Marvin H Knodel
BMC Microbiology , 2003, DOI: 10.1186/1471-2180-3-12
Abstract: The gene encoding methionine adenosyltransferase has been cloned from Mycobacterium tuberculosis and the model organism M. smegmatis. Both enzymes retained all amino acids known to be involved in catalysing the reaction. While the M. smegmatis enzyme could be functionally expressed, the M. tuberculosis homologue was insoluble and inactive under a large variety of expression conditions. For the M. smegmatis enzyme, the Vmax for S-adenosylmethionine formation was 1.30 μmol/min/mg protein and the Km for methionine and ATP was 288 μM and 76 μM respectively. In addition, the enzyme was competitively inhibited by 8-azaguanine and azathioprine with a Ki of 4.7 mM and 3.7 mM respectively. Azathioprine inhibited the in vitro growth of M. smegmatis with a minimal inhibitory concentration (MIC) of 500 μM, while the MIC for 8-azaguanine was >1.0 mM.The methionine adenosyltransferase from both organisms had a primary structure very similar those previously characterised in other prokaryotic and eukaryotic organisms. The kinetic properties of the M. smegmatis enzyme were also similar to known prokaryotic methionine adenosyltransferases. Inhibition of the enzyme by 8-azaguanine and azathioprine provides a starting point for the synthesis of higher affinity purine-based inhibitors.Tuberculosis represents one of the world's greatest sources of mortality and morbidity, with approximately 8 million new infections and 2 million deaths per year [1]. The situation regarding the control of tuberculosis has significantly worsened over the last decade, with the spread of strains resistant to multiple antimycobacterial agents. There is a profound need for the identification and development of novel chemotherapeutic compounds against tuberculosis. The characterisation of mycobacterial biochemical pathways aids this process through the identification of enzymes amenable to therapeutic inhibition.Mycobacterium tuberculosis is difficult to kill for a number of reasons. The organism is surrounded
Long-time global radiation for Central Europe derived from ISCCP Dx data
N. Petrenz, M. Sommer,F. H. Berger
Atmospheric Chemistry and Physics (ACP) & Discussions (ACPD) , 2007,
Abstract: The global Dx dataset of the International Satellite Cloud Climatology Project (ISCCP) with a spatial resolution of about 30×30 km2 was analysed to produce spatially highly resolved long-time datasets to describe the radiation budget for Central Europe over the period of 1984–2000. The computation of shortwave and longwave radiant flux densities at top of atmosphere and at surface was based on 1D radiative transfer simulations. The simulations were carried out for all relevant atmospheric and surface conditions and the results were inserted into a look-up table. Thus, long-time calculations for all conditions and time slices of the Dx dataset could be realised. The study is focussed on the global radiation at surface. The first examination was carried out for the ISCCP D1 and the ISCCP D2 dataset. These datasets, including cloud and surface information on a different spatial scale (280×280 km2), were applied to the produced look-up table analogue to the Dx data. The calculated global radiation of the D1 and D2 dataset were compared to the Dx dataset. The differences between these datasets mainly range from 5–15 Wm 2 (2–6%) with regional peaks up to 25 Wm 2 (10%). The evaluation with the GEWEX Surface Radiation Budget (SRB) data emphasises differences between 5–25 Wm 2 (6–16%) over land areas. Deviations to an ISCCP provided flux data set vary from 0 Wm 2 in the North up to 35 Wm 2 (0–13%) in the South of Central Europe. The global radiation datasets provided by the Global Energy Balance Archive (GEBA) and the German Meteorological Service (DWD) agree well, but they are 5–25 Wm 2 (7–10%) lower than the Dx results. Annual analyses of global radiation of various regional climate models complete the study. It is figured out that the used models and methods reveal a couple of discrepancies. Especially in wintertime the results of our analysis differ to the considered models. Principally the uncertainties were caused by the determined range of values and simplifications for the computation of the radiative transfer simulation.
Detecting Cosmic Strings in the CMB with the Canny Algorithm
Amsel, Stephen;Berger, Joshua;Brandenberger, Robert H.
High Energy Physics - Phenomenology , 2007, DOI: 10.1088/1475-7516/2008/04/015
Abstract: Line discontinuities in cosmic microwave background anisotropy maps are a distinctive prediction of models with cosmic strings. These signatures are visible in anisotropy maps with good angular resolution and should be identifiable using edge detection algorithms. One such algorithm is the Canny algorithm. We study the potential of this algorithm to pick out the line discontinuities generated by cosmic strings. By applying the algorithm to small-scale microwave anisotropy maps generated from theoretical models with and without cosmic strings, we find that, given an angular resolution of several minutes of arc, cosmic strings can be detected down to a limit of the mass per unit length of the string which is one order of magnitude lower than the current upper bounds.
Long-time global radiation for Central Europe derived from ISCCP Dx data
N. Petrenz,M. Sommer,F. H. Berger
Atmospheric Chemistry and Physics Discussions , 2007,
Abstract: The global Dx dataset of the "International Satellite Cloud Climatology Project" (ISCCP) with a spatial resolution of about 30×30 km2 was analysed to produce spatially highly resolved long-time datasets to describe the radiation budget for Central Europe over the period of 1984–2000. The computation of shortwave and longwave radiant flux densities at top of atmosphere and at surface was based on 1-D radiative transfer simulations. The simulations were carried out for all relevant atmospheric and surface conditions and the results were inserted into a look-up table. Thus, long-time calculations for all conditions and time slices of the Dx dataset could be realised. The study is focussed on the global radiation at surface. The first examination was carried out for the ISCCP D1 and the ISCCP D2 dataset. These datasets, including cloud and surface information on a different spatial scale (280×280 km2), were applied to the produced look-up table analogue to the Dx data. The calculated global radiation of the D1 and D2 dataset were compared to the Dx dataset. The differences between these datasets mainly range from 5–15 W m 2 (2–6%) with regional peaks up to 25 W m 2 (10%). The evaluation with the GEWEX "Surface Radiation Budget" (SRB) data emphasises differ-ences between 5–25 W m 2 (6–16%) over land areas. Deviations to an ISCCP provided flux data set vary from 0 W m 2 in the North up to 35 W m 2 (0–13%) in the South of Central Europe. The global radiation datasets provided by the "Global Energy Balance Archive" (GEBA) and the "German Meteorological Service" (DWD) agree well, but they are 5–25 W m 2 (7–10%) lower than the Dx results. Annual analyses of global radiation of various regional climate models complete the study. It is figured out that the used models and methods reveal a couple of discrepancies. Especially in wintertime the results of our analysis differ to the considered models. Principally the uncer-tainties were caused by the determined range of values and simplifications for the computation of the radiative transfer simulation.
Transgene Silencing in Wheat Transformed with the WSMV-CP Gene
Zhiwu Li,Ying Liu,Philip H. Berger
Biotechnology , 2005,
Abstract: Wheat (Triticum aestivum) was co-transformed with the bar gene and Wheat Streak Mosaic Virus Coat Protein gene (WSMV-CP) by the biolistic method. Transgenic wheat carrying the WSMV-CP showed non-uniform segregation patterns due to transgene loss or silencing. Loss of transgene expression was observed at the T1, T2 or T3 generations. Among these silenced lines, transgenic line 566B was chosen for detailed studies. Results indicated that all 566B T1 plants containing the WSMV-CP expressed WSMV coat protein and all showed strong resistance to WSMV. While the WSMV-CP was carried through to the T2 and T3 generations, all transgenic plants in these generations showed transgene silencing. Expression of WSMV-CP could be restored, at least temporarily, in most of these silenced plants by treatment with 5-azacytidine (5-AzaC).
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