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Search Results: 1 - 10 of 368419 matches for " L. P. Seaby "
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Climate change impact on groundwater levels: ensemble modelling of extreme values
J. Kidmose,J. C. Refsgaard,L. Troldborg,L. P. Seaby
Hydrology and Earth System Sciences (HESS) & Discussions (HESSD) , 2013, DOI: 10.5194/hess-17-1619-2013
Abstract: This paper presents a first attempt to estimate future groundwater levels by applying extreme value statistics on predictions from a hydrological model. Climate scenarios for the future period, 2081–2100, are represented by projections from nine combinations of three global climate models and six regional climate models, and downscaled (including bias correction) with two different methods. An integrated surface water/groundwater model is forced with precipitation, temperature, and potential evapotranspiration from the 18 models and downscaling combinations. Extreme value analyses are performed on the hydraulic head changes from a control period (1991–2010) to the future period for the 18 combinations. Hydraulic heads for return periods of 21, 50 and 100 yr (T21–100) are estimated. Three uncertainty sources are evaluated: climate models, downscaling and extreme value statistics. Of these sources, extreme value statistics dominates for return periods higher than 50 yr, whereas uncertainty from climate models and extreme value statistics are similar for lower return periods. Uncertainty from downscaling only contributes to around 10% of the uncertainty from the three sources.
Climate change impact on groundwater levels: ensemble modelling of extreme values
J. Kidmose,J. C. Refsgaard,L. Troldborg,L. P. Seaby
Hydrology and Earth System Sciences Discussions , 2012, DOI: 10.5194/hessd-9-7835-2012
Abstract: This paper presents a first attempt to estimate future groundwater levels by applying extreme value statistics on predictions from a hydrological model. Climate for the future period, 2081–2100, are represented by projections from nine combinations of three global climate models and six regional climate models, and downscaled with two different methods. An integrated surface water/groundwater model is forced with precipitation, temperature, and evapotranspiration from the 18 model – and downscaling combinations. Extreme value analyses are performed on the hydraulic head changes from a control period (1991–2010) to the future period for the 18 combinations. Hydraulic heads for return periods of 21, 50 and 100 yr (T21–100) are estimated. Three uncertainty sources are evaluated; climate models, downscaling and extreme value statistics. Of these sources, downscaling dominates for the higher return periods of 50 and 100 yr, whereas uncertainty from climate models and downscaling are similar for lower return periods. Uncertainty from the extreme value statistics only contribute up to around 10% of the uncertainty from the three sources.
Climate change effects on irrigation demands and minimum stream discharge: impact of bias-correction method
J. Rasmussen,T. O. Sonnenborg,S. Stisen,L. P. Seaby
Hydrology and Earth System Sciences Discussions , 2012, DOI: 10.5194/hessd-9-4989-2012
Abstract: Climate changes are expected to result in a warmer global climate, with increased inter-annual variability. In this study, the possible impacts of these climate changes on irrigation and low stream flow are investigated using a distributed hydrological model of a sandy catchment in western Denmark. The IPCC climate scenario A1B was chosen as the basis for the study, and meteorological forcings (precipitation, reference evapotranspiration and temperature) derived from the ECHAM5-RACMO2 regional climate model for the period 2071–2100 was applied to the model. Two bias correction methods, Delta Change and Distribution-Based Scaling, were used to evaluate the importance of the bias correction method. Using the annual irrigation amounts, the minimum stream flow, the median minimum stream flow and the mean stream flow as indicators, the irrigation and the stream flow predicted using the two methods were compared. The study found that irrigation is significantly underestimated and low stream flow in overestimated when using the delta change method, due to the inability of this method to account for changes in inter-annual variability of precipitation and reference ET and the resulting effects on irrigation demands. Additionally, future increases in CO2 are found to have a significant effect on both irrigation and low flow, due to reduced transpiration from plants.
Elevation correction of ERA-Interim temperature data in complex terrain
J. Rasmussen, T. O. Sonnenborg, S. Stisen, L. P. Seaby, B. S. B. Christensen,K. Hinsby
Hydrology and Earth System Sciences (HESS) & Discussions (HESSD) , 2012,
Abstract: Climate changes are expected to result in a warmer global climate, with increased inter-annual variability. In this study, the possible impacts of these climate changes on irrigation and low stream flow are investigated using a distributed hydrological model of a sandy catchment in western Denmark. The IPCC climate scenario A1B was chosen as the basis for the study, and meteorological forcings (precipitation, reference evapotranspiration and temperature) derived from the ECHAM5-RACMO regional climate model for the period 2071–2100 was applied to the model. Two bias correction methods, delta change and Distribution-Based Scaling, were used to evaluate the importance of the bias correction method. Using the annual irrigation amounts, the 5-percentile stream flow, the median minimum stream flow and the mean stream flow as indicators, the irrigation and the stream flow predicted using the two methods were compared. The study found that irrigation is significantly underestimated when using the delta change method, due to the inability of this method to account for changes in inter-annual variability of precipitation and reference ET and the resulting effects on irrigation demands. However, this underestimation of irrigation did not result in a significantly higher summer stream flow, because the summer stream flow in the studied catchment is controlled by the winter and spring recharge, rather than the summer precipitation. Additionally, future increases in CO2 are found to have a significant effect on both irrigation and low flow, due to reduced transpiration from plants.
Study of Decoherence of Elementary Gates Implemented in a Chain of Few Nuclear Spins Quantum Computer Model  [PDF]
G. V. López, P. López
Journal of Modern Physics (JMP) , 2012, DOI: 10.4236/jmp.2012.31013
Abstract: We study the phenomenon of decoherence during the operation of one qubit transformation, controlled-not (CNOT) and controlled-controlled-not (C2NOT) quantum gates in a quantum computer model formed by a linear chain of three nuclear spins system. We make this study with different type of environments, and we determine the associated decoherence time as a function of the dissipative parameter. We found that the dissipation parameter to get a well defined quantum gates (without significant decoherence) must be within the range of . We also study the behavior of the purity parameter for these gates and different environments and found linear or quadratic decays of this parameter depending on the type of environments.
Study of Decoherence on the Teleportation Algorithm in a Chain of Three Nuclear Spins System  [PDF]
G. V. López, P. López
Journal of Modern Physics (JMP) , 2013, DOI: 10.4236/jmp.2013.41012
Abstract:

We make a numerical study of decoherence on the teleportation algorithm implemented in a linear chain of three nuclear spins system. We study different types of environments, and we determine the associated decoherence time as a function of the dissipative parameter. We found that the dissipation parameter to get a well defined quantum gates (without significant decoherence) must be within the range of γ4×10-4 for not thermalized case, which was determined by using the purity parameter calculated at the end of the algorithm. For the thermalized case the decoherence is stablished for very small dissipation parameter, making almost not possible to implement this algorithm for not zero temperature.

Asplenium nidus; The Bird’s Nest Fern: Developmental Studies and Its Conservation  [PDF]
Ruchi Srivastava, P. L. Uniyal
American Journal of Plant Sciences (AJPS) , 2013, DOI: 10.4236/ajps.2013.45A007
Abstract:

Asplenium nidus L. commonly called as Bird’s Nest Fern, is a threatened, ornamental fern, which is widely used as novel foliage ornamental plant and local people use it in worship. The taxon is threatened due to over exploitation, habitat destruction and genetic barriers. To understand the constraints in the regeneration, reproductive biology studies are made. It is observed that more sporophytes are produced in composite population (13.3%) in comparison to isolate population (10%). This pattern is suggestive of the fact that the parental sporophyte is heterozygous for recessive sporophytic lethal. On the basis of the results obtained A. nidus was initially adapted for outbreeding with the capacity for considerable amount of inbreeding. The low potential of sporophyte production in isolate gametophyte could be the constitution of the zygotic genotype.

DC Electrical Conductivity Studies of GeO2 Doped Lead Vanadate Glass System  [PDF]
P. Tejeswararao, D. L. Sastry
New Journal of Glass and Ceramics (NJGC) , 2017, DOI: 10.4236/njgc.2017.73005
Abstract: Temperature dependent DC electrical conductivity studies of GeO2 substituted lead vanadate glass systems xGeO2(50-x)PbO:50V2O5 (x = 5, 10, 15 mole%) were carried out and the results are reported. X-ray diffraction results reveal that all samples are perfect amorphous in nature. DSC results indicate that the substituent GeO2 is replacing PbO in the glass network in such a way that the eutectic composition is maintained. DC electrical conductivity studies of the glass samples indicate that the systems are characterized by different activation energies in different temperature ranges which in turn depend on the annealing temperature. These results are interpreted in terms of temperature dependent microstructural changes in these glass systems.
Recent acquisition of imprinting at the rodent Sfmbt2 locus correlates with insertion of a large block of miRNAs
Qianwei Wang, Jacqueline Chow, Jenny Hong, Anne Smith, Carol Moreno, Peter Seaby, Paul Vrana, Kamelia Miri, Joon Tak, Eu Ddeum Chung, Gabriela Mastromonaco, Isabella Caniggia, Susannah Varmuza
BMC Genomics , 2011, DOI: 10.1186/1471-2164-12-204
Abstract: We analyzed allelic expression of approximately 20 genes within a 3.9 Mb domain and found that Sfmbt2 and an overlapping non-coding antisense transcript are the only imprinted genes in this region. These transcripts represent a very narrow imprinted gene locus. We also demonstrate that rat Sfmbt2 is imprinted in extraembryonic tissues. An interesting feature of both mouse and rat Sfmbt2 genes is the presence of a large block of miRNAs in intron 10. Other mammals, including the bovine, lack this block of miRNAs. Consistent with this association, we show that human and bovine Sfmbt2 are biallelic. Other evidence indicates that pig Sfmbt2 is also not imprinted. Further strengthening the argument for recent evolution of Sfmbt2 is our demonstration that a more distant muroid rodent, Peromyscus also lacks imprinting and the block of miRNAs.These observations are consistent with the hypothesis that the block of miRNAs are driving imprinting at this locus. Our results are discussed in the context of ncRNAs at other imprinted loci.Accession numbers for Peromyscus cDNA and intron 10 genomic DNA are [Genbank:HQ416417 and Genbank:HQ416418], respectively.Genomic imprinting is an epigenetic process that affects a small subset of genes resulting in their expression/repression in a parent of origin dependent fashion. One set of imprinted genes is expressed only from the paternally inherited allele, while another set is expressed only from the maternally inherited chromosome. The imprint is reset at each generation when the two haploid genomes are separate, either during gametogenesis or immediately after fertilization, when the two genomes are physically separated in their own pronuclei.Imprinted genes generally reside in clusters around a cis acting element called an Imprinting Control Region (ICR) that exerts its effects over a large chromosomal domain (up to 4 Mb) (reviewed in [1]). Imprinted domains can contain genes that are biallelic, paternally expressed or maternally expres
The Synthesis of Solvent-Free TiO2 Nanofluids through Surface Modification  [PDF]
P. Y. Yu, Y. P. Zheng, L. Lan
Soft Nanoscience Letters (SNL) , 2011, DOI: 10.4236/snl.2011.12008
Abstract: TiO2 nanoparticles with surface hydroxyl groups are treated by trimethoxysilane (CH3O)3Si(CH2)3O(CH2CH2O)6-9CH3 and a inorganic core/organic shell hybridmaterials, which shows itself a yellow viscous fluid, is obtained. We call it solvent-free TiO2 nanofliuds. Transmission electron microscopy (TEM), Fourier transform infrared spectrum (FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and rheometer are adopted to characterize the product. As a result, the content of TiO2 nanoparticles in the nanofliuds is about 5.5wt%, the functionalized TiO2 nanoparticles possess better dispersion, very low viscosity and an obvious liquid-like behavior at room temperature in absence of solvent.
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