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Search Results: 1 - 10 of 401174 matches for " M. Morgenstern "
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Triggering On Hadronic Tau Decays: A challenge met by ATLAS
Morgenstern Marcus M.
EPJ Web of Conferences , 2012, DOI: 10.1051/epjconf/20122812006
Abstract: The ATLAS experiment at the Large Hadron Collider (LHC) has been able to collect 5.25 fb 1 of data in 2011. For many physics analyses both in context of the Standard Model (SM) and Beyond the Standard Model (BSM) theories such as Higgs boson searches, tau leptons play an important role. Thus, triggering on hadronic tau decays is an essential ingredient for the success of those measurements. This contribution will summarize the developed efforts to meet this challenge. Efficiency measurements using data taken in 2011 at a center-of-mass energy of 7 TeV are described and results are presented. An outlook on further developments of the tau trigger algorithms, to match future requirements and higher instantaneous luminosities are summarised in the end.
Dating of streamwater using tritium in a post nuclear bomb pulse world: continuous variation of mean transit time with streamflow
U. Morgenstern, M. K. Stewart,R. Stenger
Hydrology and Earth System Sciences (HESS) & Discussions (HESSD) , 2010,
Abstract: Tritium measurements of streamwater draining the Toenepi catchment, a small dairy farming area in Waikato, New Zealand, have shown that the mean transit time of the water varies with the flow rate of the stream. Mean transit times through the catchment are 2–5 years during high baseflow conditions in winter, increasing to 30–40 years as baseflow decreases in summer, and then dramatically older water during drought conditions with mean transit time of more than 100 years. Older water is gained in the lower reaches of the stream, compared to younger water in the headwater catchment. The groundwater store supplying baseflow was estimated from the mean transit time and average baseflow to be 15.4 × 106 m3 of water, about 1 m water equivalent over the catchment and 2.3 times total annual streamflow. Nitrate is relatively high at higher flow rates in winter, but is low at times of low flow with old water. This reflects both lower nitrate loading in the catchment several decades ago as compared to current intensive dairy farming, and denitrification processes occurring in the older groundwater. Silica, leached from the aquifer material and accumulating in the water in proportion to contact time, is high at times of low streamflow with old water. There was a good correlation between silica concentration and streamwater age, which potentially allows silica concentrations to be used as a proxy for age when calibrated by tritium measurements. This study shows that tritium dating of stream water is possible with single tritium measurements now that bomb-test tritium has effectively disappeared from hydrological systems in New Zealand, without the need for time-series data.
Dating of streamwater using tritium in a post-bomb world: continuous variation of mean transit time with streamflow
U. Morgenstern,M. K. Stewart,R. Stenger
Hydrology and Earth System Sciences Discussions , 2010, DOI: 10.5194/hessd-7-4731-2010
Abstract: Tritium measurements of streamwater draining the Toenepi catchment, a small dairy farming area in Waikato, New Zealand, have shown that the mean transit time of the water varies with the flow of the stream. Mean transit times through the catchment are 2–5 years during high baseflow conditions (in winter), becoming older as streamflow decreases (in summer), and then quite dramatically older during drought conditions, with ages of more than 100 years. Older water seems to be gained in the lower reaches of the stream, compared to younger water in the headwater catchment. The groundwater store supplying baseflow was estimated from the mean transit time and average baseflow to be 15.4×106 m3 of water, about 1 m water equivalent over the catchment and 2.3 times total annual streamflow. Nitrate from recent intensified land use is relatively high at normal streamflow, but is low at times of low flow with old water. This reflects both lower nitrate loading in the catchment several decades ago, and active denitrification processes in older groundwater. Silica, leached from the aquifer material and accumulating in the water in proportion to contact time, is high at times of low streamflow. There was a good correlation between silica and streamwater age, which potentially allows silica concentrations to be used as a proxy for age when calibrated by tritium measurements. This study shows that tritium dating of stream water is possible with single tritium measurements now that bomb-test tritium has effectively disappeared from hydrological systems in New Zealand, without the need for time-series data.
Gundlach oscillations and Coulomb blockade of Co nano-islands on MgO/Mo(100) investigated by scanning tunneling spectroscopy at 300 K
C. Pauly,M. Grob,M. Pezzotta,M. Pratzer,M. Morgenstern
Physics , 2010, DOI: 10.1103/PhysRevB.81.125446
Abstract: Ultrathin MgO films on Mo(100) with a thickness up to 12 ML are studied by scanning tunneling microscopy and spectroscopy at room temperature. The spatial variation of the work function within the MgO film is mapped by field emission resonance states (Gundlach oscillations) using dz/dU spectroscopy. We found circular spots with significantly reduced work function (DeltaPhi=0.6 eV), which are assigned to charged defects within the MgO film. On top of the MgO films, small Co cluster are deposited with an average contact area of 4 nm^2. These islands exhibit Coulomb oscillations in dI/dU spectra at room temperature. Good agreement with orthodox theory is achieved showing variations of the background charge Q_0 for islands at different positions, which are in accordance with the work function differences determined by the Gundlach oscillations.
Catalytic Growth of N-doped MgO on Mo(001)
M. Grob,M. Pratzer,M. Le?ai?,M. Morgenstern
Physics , 2012, DOI: 10.1103/PhysRevB.86.075455
Abstract: A simple pathway to grow thin films of N-doped MgO (MgO:N), which has been found experimentally to be a ferromagnetic d0 insulator, is presented. It relies on the catalytic properties of a Mo(001) substrate using growth of Mg in a mixed atmosphere of O2 and N2. Scanning tunneling spectroscopy reveals that the films are insulating and exhibit an N-induced state slightly below the conduction band minimum.
Calibration of a transient transport model to tritium data in streams and simulation of groundwater ages in the western Lake Taupo catchment, New Zealand
M. A. Gusyev,M. Toews,U. Morgenstern,M. Stewart
Hydrology and Earth System Sciences (HESS) & Discussions (HESSD) , 2013, DOI: 10.5194/hess-17-1217-2013
Abstract: Here we present a general approach of calibrating transient transport models to tritium concentrations in river waters developed for the MT3DMS/MODFLOW model of the western Lake Taupo catchment, New Zealand. Tritium has a known pulse-shaped input to groundwater systems due to the bomb tritium in the early 1960s and, with its radioactive half-life of 12.32 yr, allows for the determination of the groundwater age. In the transport model, the tritium input (measured in rainfall) passes through the groundwater system, and the simulated tritium concentrations are matched to the measured tritium concentrations in the river and stream outlets for the Waihaha, Whanganui, Whareroa, Kuratau and Omori catchments from 2000–2007. For the Kuratau River, tritium was also measured between 1960 and 1970, which allowed us to fine-tune the transport model for the simulated bomb-peak tritium concentrations. In order to incorporate small surface water features in detail, an 80 m uniform grid cell size was selected in the steady-state MODFLOW model for the model area of 1072 km2. The groundwater flow model was first calibrated to groundwater levels and stream baseflow observations. Then, the transient tritium transport MT3DMS model was matched to the measured tritium concentrations in streams and rivers, which are the natural discharge of the groundwater system. The tritium concentrations in the rivers and streams correspond to the residence time of the water in the groundwater system (groundwater age) and mixing of water with different age. The transport model output showed a good agreement with the measured tritium values. Finally, the tritium-calibrated MT3DMS model is applied to simulate groundwater ages, which are used to obtain groundwater age distributions with mean residence times (MRTs) in streams and rivers for the five catchments. The effect of regional and local hydrogeology on the simulated groundwater ages is investigated by demonstrating groundwater ages at five model cross-sections to better understand MRTs simulated with tritium-calibrated MT3DMS and lumped parameter models.
Calibration of a transient transport model to tritium measurements in rivers and streams in the Western Lake Taupo catchment, New Zealand
M. A. Gusyev,M. Toews,U. Morgenstern,M. Stewart
Hydrology and Earth System Sciences Discussions , 2012, DOI: 10.5194/hessd-9-9743-2012
Abstract: Here we present a general approach of calibrating transient transport models to tritium concentrations in river waters developed for the MT3DMS/MODFLOW model of the Western Lake Taupo catchment, New Zealand. Tritium is a time-dependent tracer with radioactive half-life of 12.32 yr. In the transport model, the tritium input (measured in rain) passes through the groundwater system, and the modelled tritium concentrations are compared to the measured tritium concentrations in the river outlets for the Waihaha, Whanganui, Whareroa, Kuratau and Omori river catchments from 2000–2007. For the Kuratau River, tritium was also measured between 1960 and 1970, which allowed us to fine-tune the transport model. In order to incorporate all surface flows from rivers to small streams, an 80 m uniform grid cell size was selected in the steady-state MODFLOW model for the model area of 1072 km2. The groundwater flow model was first calibrated to groundwater levels and stream flow observations. Then, the transport model was calibrated to the measured tritium concentrations in the river waters. The MT3DMS model results show good agreement with the measured tritium values in all five river catchments. Finally, the calibrated MT3DMS model is applied to simulate groundwater ages that are used to construct groundwater age distributions for the river catchments.
Scanning tunneling spectroscopy of a dilute two-dimensional electron system exhibiting Rashba spin splitting
S. Becker,M. Liebmann,T. Mashoff,M. Pratzer,M. Morgenstern
Physics , 2010, DOI: 10.1103/PhysRevB.81.155308
Abstract: Using scanning tunneling spectroscopy (STS) at 5 K in B-fields up to 7 T, we investigate the local density of states of a two-dimensional electron system (2DES) created by Cs adsorption on p-type InSb(110). The 2DES, which in contrast to previous STS studies exhibits a 2D Fermi level, shows standing waves at B = 0 T with corrugations decreasing with energy and with wave numbers in accordance with theory. In magnetic field percolating drift states are observed within the disorder broadened Landau levels. Due to the large electric field perpendicular to the surface, a beating pattern of the Landau levels is found and explained quantitatively by Rashba spin splitting within the lowest 2DES subband. The Rashba splitting does not contribute significantly to the standing wave patterns in accordance with theory.
Ineffectiveness of Nickel in augmenting the hepatotoxicity in protein deficient rats Eficacia del níquel en aumentar la hepatotoxicidad en ratas con deficiencia en proteínas
P. Sidhu,M. L. Garg,P. Morgenstern,J. Vogt
Nutrición Hospitalaria , 2005,
Abstract: This study was designed to determine the toxic effects of nickel sulfate on the biochemical and elemental profile of liver in protein deficient rats. Nickel sulfate in the dose of 800mg/l in drinking water was administrated to Sprauge Dawley (S.D) normal control as well as protein deficient rats for a total duration of eight weeks. The effects of nickel treatment and protein deficiency when given separately and in combination were studied on rat liver marker enzymes like Alkaline phosphatase (ALP),Glutamate oxaloacetate transaminase (GOT), Glutamate pyruvate transaminase (GPT) and also on the status of essential elements in rat liver. Protein deficient,Ni treated as well as combined protein deficient and nickel treated rats showed significant reductions in the body weight and hepatic protein contents as compared to normal control rats. Hepatic alkaline phosphatase activity and alanine aminotransferase showed a significant elevation in rats subjected to protein deficiency, nickel treatment and combined protein deficiency and nickel treatment.As regards to hepatic levels of aspartate aminotransferase a significant elevation was observed in protein deficient and nickel treated protein deficient animals. Nickel administration to normal and protein deficient rats has resulted in a significant increase in concentrations of nickel, phosphorus and sulfur in liver tissue. The concentration of zinc and copper in liver tissue decreased significantly in protein deficient, nickel treated and nickel treated protein deficient animals. Tissue iron concentrations were found to be decreased in protein deficient animals, but the concentrations of iron got elevated significantly in nickel treated and nickel treated protein deficient animals. It has been observed that selenium got decreased significantly in protein deficient, nickel treated and nickel treated protein deficient animals when compared to normal animals. The elevation of selenium in nickel treated protein deficient animals was also significantly higher when compared to protein deficient animals. Este estudio fue dise ado para determinar los efectos tóxicos del sulfato de níquel sobre el perfil bioquímico y de oligoelementos del hígado en ratas con deficiencia de proteínas.Se administró sulfato de níquel, a la dosis de 800 mg/l, en el agua de bebida de ratas Sprauge Dawley (S-D) normales control y con deficiencia de proteínas, durante 8 semanas. Se estudiaron los efectos del tratamiento con níquel y de la deficiencia de proteínas, por separado y en combinación,sobre marcadores enzimáticos hepáticos de la rata com
Grupos organizados y partidos desorganizados: incentivos electorales en Uruguay Organized factions and disorganized parties: electoral incentives in Uruguay
Scott MORGENSTERN
América Latina Hoy , 2010,
Abstract: El presente artículo aplica el estudio de la organización de partidos y el voto legislativo a sistemas de partidos con facciones. Tras desarrollar una clasificación de los diferentes tipos de facciones, se argumenta que las facciones jerárquicamente organizadas responden a un sistema competitivo de incentivos. Pese a que las facciones tienen intereses que las empujan a trabajar juntas por el bien del partido, al mismo tiempo, tienen interés en diferenciarse unas de otras por propósitos electorales. Además, el ciclo electoral dirige los pesos de estas presiones competitivas provocando la ruptura en la cooperación entre las facciones conforme se aproximan las elecciones. Estas pautas e incentivos son particularmente evidentes en el caso de Uruguay, por lo que el artículo utiliza datos del voto nominal del Legislativo del país para probar estos argumentos. This paper extends the study of party organization and legislative voting to factionalize party systems. After developing a typology of factional types, it argues that hierarchically organized factions respond to a competing incentive system. Factions have interests that push them to work together for the good of the party, but at the same time, they have interests in distinguishing themselves for electoral purposes. Further, the electoral cycle drives the weights of these competing pressures, leading factional cooperation to break down as elections near. These patterns and incentives are particularly evident in Uruguay, and the paper uses roll-call data from that country's legislature to test the propositions
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