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Search Results: 1 - 10 of 461782 matches for " A. Muhlbauer "
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Intercomparison of aerosol-cloud-precipitation interactions in stratiform orographic mixed-phase clouds
A. Muhlbauer,T. Hashino,L. Xue,A. Teller
Atmospheric Chemistry and Physics Discussions , 2010, DOI: 10.5194/acpd-10-10487-2010
Abstract: Anthropogenic aerosols serve as a source of both cloud condensation nuclei (CCN) and ice nuclei (IN) and affect microphysical properties of clouds. Increasing aerosol number concentrations is hypothesized to retard the cloud droplet collision/coalescence and the riming in mixed-phase clouds, thereby decreasing orographic precipitation. This study presents results from a model intercomparison of 2-D simulations of aerosol-cloud-precipitation interactions in stratiform orographic mixed-phase clouds. The sensitivity of orographic precipitation to changes in the aerosol number concentrations is analyzed and compared for various dynamical and thermodynamical situations. Furthermore, the sensitivities of microphysical processes such as collision/coalescence, aggregation and riming to changes in the aerosol number concentrations are evaluated and compared. The participating models are the Consortium for Small-Scale Modeling's (COSMO) model with bulk-microphysics, the Weather Research and Forecasting (WRF) model with bin-microphysics and the University of Wisconsin modeling system (UWNMS) with a spectral ice-habit prediction microphysics scheme. All models are operated on a cloud-resolving scale with 2 km horizontal grid spacing. The results of the model intercomparison suggest that the sensitivity of orographic precipitation to aerosol modifications varies greatly from case to case and from model to model. Neither a precipitation decrease nor a precipitation increase is found robustly in all simulations. Qualitative robust results can only be found for a subset of the simulations but even then quantitative agreement is scarce. Estimates of the second indirect aerosol effect on orographic precipitation are found to range from –19% to 0% depending on the simulated case and the model. Similarly, riming is shown to decrease in some cases and models whereas it increases in others which implies that a decrease in riming with increasing aerosol load is not a robust result. Furthermore, it is found that neither a decrease in cloud droplet coalescence nor a decrease in riming necessarily implies a decrease in precipitation due to compensation effects by other microphysical pathways. The simulations suggest that mixed-phase conditions play an important role in reducing the overall susceptibility of clouds and precipitation with respect to changes in the aerosols number concentrations. As a consequence the indirect aerosol effect on precipitation is suggested to be less pronounced or even inverted in regions with high terrain (e.g., the Alps or Rocky Mountains) or in reg
Phase Diagram of the Dzyaloshinskii-Moriya Helimagnet Ba2CuGe2O7 in Canted Magnetic Fields
S. Muhlbauer,S. Gvasaliya,E. Pomjakushina,A. Zheludev
Physics , 2012, DOI: 10.1103/PhysRevB.86.024417
Abstract: The evolution of different magnetic structures of non-centrosymmetric Ba2CuGe2O7 is systematically studied as function of the orientation of the magnetic field H. Neutron diffraction in combination with measurements of magnetization and specific heat show a virtually identical behaviour of the phase diagram of Ba2CuGe2O7 for H confined in both the (1,0,0) and (1,1,0) plane. The existence of a recently proposed incommensurate double-k AF-cone phase is confirmed in a narrow range for H close to the tetragonal c-axis. For large angles enclosed by H and the c-axis a complexely distorted non-sinusoidal magnetic structure has recently been observed. We show that its critical field Hc systematically increases for larger canting. Measurements of magnetic susceptibility and specific heat finally indicate the existence of an incommensurate/commensurate transition for H /sim 9 T applied in the basal (a,b)-plane and agree with a non-planar, distorted cycloidal magnetic structure.
Spectral and thermodynamic properties of a strong-leg quantum spin ladder
D. Schmidiger,P. Bouillot,S. Muhlbauer,S. Gvasaliya,C. Kollath,T. Giamarchi,A. Zheludev
Physics , 2011, DOI: 10.1103/PhysRevLett.108.167201
Abstract: The strong-leg S=1/2 Heisenberg spin ladder system (C7H10N)2CuBr4 is investigated using Density Matrix Renormalization Group (DMRG) calculations, inelastic neutron scattering, and bulk magneto-thermodynamic measurements. Measurements showed qualitative differences compared to the strong-rung case. A long-lived two-triplon bound state is confirmed to persist across most of the Brillouin zone in zero field. In applied fields, in the Tomonaga-Luttinger spin liquid phase, elementary excitations are attractive, rather than repulsive. In the presence of weak inter-ladder interactions, the strong-leg system is considerably more prone to 3-dimensional ordering.
Intercomparison of aerosol-cloud-precipitation interactions in stratiform orographic mixed-phase clouds
A. Muhlbauer, T. Hashino, L. Xue, A. Teller, U. Lohmann, R. M. Rasmussen, I. Geresdi,Z. Pan
Atmospheric Chemistry and Physics (ACP) & Discussions (ACPD) , 2010,
Abstract: Anthropogenic aerosols serve as a source of both cloud condensation nuclei (CCN) and ice nuclei (IN) and affect microphysical properties of clouds. Increasing aerosol number concentrations is hypothesized to retard the cloud droplet coalescence and the riming in mixed-phase clouds, thereby decreasing orographic precipitation. This study presents results from a model intercomparison of 2-D simulations of aerosol-cloud-precipitation interactions in stratiform orographic mixed-phase clouds. The sensitivity of orographic precipitation to changes in the aerosol number concentrations is analysed and compared for various dynamical and thermodynamical situations. Furthermore, the sensitivities of microphysical processes such as coalescence, aggregation, riming and diffusional growth to changes in the aerosol number concentrations are evaluated and compared. The participating numerical models are the model from the Consortium for Small-Scale Modeling (COSMO) with bulk microphysics, the Weather Research and Forecasting (WRF) model with bin microphysics and the University of Wisconsin modeling system (UWNMS) with a spectral ice habit prediction microphysics scheme. All models are operated on a cloud-resolving scale with 2 km horizontal grid spacing. The results of the model intercomparison suggest that the sensitivity of orographic precipitation to aerosol modifications varies greatly from case to case and from model to model. Neither a precipitation decrease nor a precipitation increase is found robustly in all simulations. Qualitative robust results can only be found for a subset of the simulations but even then quantitative agreement is scarce. Estimates of the aerosol effect on orographic precipitation are found to range from 19% to 0% depending on the simulated case and the model. Similarly, riming is shown to decrease in some cases and models whereas it increases in others, which implies that a decrease in riming with increasing aerosol load is not a robust result. Furthermore, it is found that neither a decrease in cloud droplet coalescence nor a decrease in riming necessarily implies a decrease in precipitation due to compensation effects by other microphysical pathways. The simulations suggest that mixed-phase conditions play an important role in buffering the effect of aerosol perturbations on cloud microphysics and reducing the overall susceptibility of clouds and precipitation to changes in the aerosol number concentrations. As a consequence the aerosol effect on precipitation is suggested to be less pronounced or even inverted in regions with high terrain (e.g., the Alps or Rocky Mountains) or in regions where mixed-phase microphysics is important for the climatology of orographic precipitation.
The relationship between serum sodium and intracranial pressure when using hypertonic saline to target mild hypernatremia in patients with head trauma
Diana L Wells, Joseph M Swanson, G Christopher Wood, Louis J Magnotti, Bradley A Boucher, Martin A Croce, Charles G Harrison, Michael S Muhlbauer, Timothy C Fabian
Critical Care , 2012, DOI: 10.1186/cc11678
Abstract: A retrospective review of patients who were admitted to the trauma ICU for TBI, had an ICP monitor placed, and received at least one dose of HTS between January 2006 and March 2011 was performed. Data were collected for up to 120 hours after ICP monitor placement. The primary outcome was the relationship between serum sodium and maximum ICP. Secondary outcomes were the relationship between serum sodium and the mean number of daily interventions for ICP control, and the acute effect of HTS on ICP during the 6 hours after each dose. Linear regression was used to analyze the primary outcome. Analysis of variance on ranks and repeated measures analysis of variance were used to evaluate the number of interventions and the acute effect of HTS on ICP, respectively.Eighty-one patients were enrolled with mean ± standard deviation age of 36 ± 15 years and median Glasgow Coma Scale score of 7 (interquartile range, 4 to 7). A total of 1,230 serum sodium values (range, 118 to174 mEq/l) and 7,483 ICP values (range, 0 to 159 mmHg) were collected. There was no correlation between serum sodium and maximum ICP (R2 = 0.0052). The overall mean ± standard deviation number of interventions for elevated ICP per day was 4.2 ± 2.9, 2.9 ± 2.0, and 2.6 ± 2.3 for patients with a mean serum sodium of < 145, 145 to 155, and > 155 mEq/l, respectively (P < 0.001). Regarding the acute effect of HTS on ICP, there was no statistical difference in mean ICP compared with baseline during hours 1 through 6 following HTS doses (baseline, 13.7 ± 8.4 mmHg; hour 1, 13.6 ± 8.3 mmHg; hour 2, 13.5 ± 8.8 mmHg; hour 3, 13.3 ± 8.7 mmHg; hour 4, 13.4 ± 8.7 mmHg; hour 5, 13.4 ± 8.3 mmHg; hour 6, 13.5 ± 8.3 mmHg; P = 0.84).Serum sodium concentrations did not correlate with ICP values. These results warrant further evaluation and possible reassessment of sodium goals for ICP management in patients with TBI.Traumatic brain injury (TBI) is the leading cause of morbidity and mortality in young adults [1]. When treating T
SIMPLE PAST TENSE MARKERS IN TURKISH AND SOME AMERICAN INDIAN LANGUAGES IN TERMS OF EVIDENTIALITY DEL LE DAYALILIK BAKIMINDAN TüRK YE TüRK ES LE BAZI KIZILDER L D LLER NDE BAS T EK ML GE M ZAMANLAR
Kerim DEM?RC?,Jeff MUHLBAUER,Clare COOK
Turkish Studies , 2010,
Abstract: This descriptive study examines the term ‘evidentiality’ within the context of Turkish of Turkey and some American Indian languages. In the broadest sense, as a linguistic category evidentiality is the morphological indication of an event that takes place in the past and the relation of this event to the speaker. It is a kind of ‘verification system’ that languages mark with affixes, conveying the perspective of the speaker. The witnessed past tense marker –DI and the reported past tense marker –mI in Turkish are two good examples of evidentiality. It is a cross-linguistic phenomenon that specifies whether the speaker has witnessed the event or learned it from somebody else. It can be seen at various levels in several languages. Starting from two the number of suffixes added to the verb stems indicating the position of the speaker with respect to the event may go up to as many as six. In this study, examples from some American Indian languages spoken in North America and Turkish of Turkey will be examined. Bu al ma Türkiye Türk esi ve baz K z lderili dilleri ba lam nda ‘delile dayal l k’ terimini incelemektedir. Dilbilgisel bir s n f olarak delile dayal l k, en geni anlam yla baz dillerde, bir konu ucunun s yledi i s zün kayna n ge mi zaman g steren bi imbirimsel yap larla dinleyiciye aktarmas demektir. Anlat lan ‘do rulama sistemi’ veya anlat c n n olay kar s ndaki konumu olarak da nitelendirilebilen bu dil bilgisel kategori kendini en iyi ekilde Türkiye Türk esinde g rülen ge mi zaman (-DI) ve renilen ge mi zaman (-mI ) ay r m nda g sterir. Farkl dillerde e itli seviyelerde kar la lan bu dil olay nda anlat c n n olay g rüp g rmedi i veya farkl kaynaklardan duyup duymad morfolojik yollarla vurgulan r. De i ik dillerde fiile eklenerek konu ucuyu konumland ran eklerin say s ikiden alt ya kadar kabilmektedir. Bu al mada Kuzey ve Güney Amerika’da konu ulan baz K z lderili dilleri ve Türkiye Türk esi rnekleri ele al nmaktad r.
Do Multiple Isolated Vertebral Thoracolumbar Transverse Process Fractures Increase the Risk of Ligamentous Injury and Surgical Intervention in the Setting of Trauma?  [PDF]
Nickalus Khan, Jonathan Reding, Matthew Gilbert, Michael S. Muhlbauer, L. Madison Michael
Open Journal of Modern Neurosurgery (OJMN) , 2018, DOI: 10.4236/ojmn.2018.81006
Abstract: Background: Isolated thoracolumbar vertebral transverse process fractures (TPF) are often considered a stable injury. However, the use of advanced imaging such as magnetic resonance imaging and spine specialist consultation are often ordered as part of the routine workup of these fractures. The routine ordering of advanced imaging, spine specialist consultation, and delayed mobilization causes unnecessary economic and clinical burdens to patients and the overall healthcare system. Purpose: To determine if a higher number of isolated TPFs (iTPFs) lead to an increase in ligamentous injury to the spine, and whether ligamentous injury—if present—requires surgical intervention. Methods: The retrospective review was performed from 2009 to 2015, using a surgical trauma database to identify patients with greater than 3 isolated TPF (iTPF) to determine if iTPF leads to an increase in ligamentous injury to the spine and if this increase leads to increased surgical intervention. Results: A total of 102 patients were identified with complete follow up at 6 - 8 weeks post injury. The majority of the included patients suffered from blunt trauma. There was a small rate of ligamentous injury (n = 7, 7%) that did not require additional treatment. None of the fractures included were considered unstable. None of the patients included required surgical intervention during their hospital visit or in follow up visits. Conclusion: iTPFs are a stable injury to the thoracolumbar spine. There is a small rate of associated ligamentous injury that does not change the management or require further interventions. Thoracolumbar iTPFs do not automatically need spine specialist consultation and advanced imaging techniques.
Unexpected edge conduction in HgTe quantum wells under broken time reversal symmetry
Eric Yue Ma,M. Reyes Calvo,Jing Wang,Biao Lian,Mathias Muhlbauer Christoph Brune,Yong-Tao Cui,Keji Lai,Worasom Kundhikanjana,Yongliang Yang,Matthias Baenninger,Markus Konig,Christopher Ames,Hartmut Buhmann,Philipp Leubner,Laurens W. Molenkamp,Shou-Cheng Zhang,David Goldhaber-Gordon,Michael K. Kelly,Zhi-Xun Shen
Physics , 2012, DOI: 10.1038/ncomms8252
Abstract: The realization of quantum spin Hall (QSH) effect in HgTe quantum wells (QWs) is considered a milestone in the discovery of topological insulators. The QSH edge states are predicted to allow current to flow at the edges of an insulating bulk, as demonstrated in various experiments. A key prediction of QSH theory that remains to be experimentally verified is the breakdown of the edge conduction under broken time reversal symmetry (TRS). Here we first establish a rigorous framework for understanding the magnetic field dependence of electrostatically gated QSH devices. We then report unexpected edge conduction under broken TRS, using a unique cryogenic microwave impedance microscopy (MIM), on a 7.5 nm HgTe QW device with an inverted band structure. At zero magnetic field and low carrier densities, clear edge conduction is observed in the local conductivity profile of this device but not in the 5.5 nm control device whose band structure is trivial. Surprisingly, the edge conduction in the 7.5 nm device persists up to 9 T with little effect from the magnetic field. This indicates physics beyond simple QSH models, possibly associated with material- specific properties, other symmetry protection and/or electron-electron interactions.
The Spread of Infectious Disease on Network Using Neutrosophic Algebraic Structure  [PDF]
A. Zubairu, A. A. Ibrahim
Open Journal of Discrete Mathematics (OJDM) , 2017, DOI: 10.4236/ojdm.2017.72009
Abstract: Network theory and its associated techniques has tremendous impact in various discipline and research, from computer, engineering, architecture, humanities, social science to system biology. However in recent years epidemiology can be said to utilizes these potentials of network theory more than any other discipline. Graph which has been considered as the processor in network theory has a close relationship with epidemiology that dated as far back as early 1900 [1]. This is because the earliest models of infectious disease transfer were in a form of compartment which defines a graph even though adequate knowledge of mathematical computation and mechanistic behavior is scarce. This paper introduces a new type of disease propagation on network utilizing the potentials of neutrosophic algebraic group structures and graph theory.
A Comparative Investigation of Lead Sulfate and Lead Oxide Sulfate Study of Morphology and Thermal Decomposition  [PDF]
S. A. A. Sajadi
American Journal of Analytical Chemistry (AJAC) , 2011, DOI: 10.4236/ajac.2011.22024
Abstract: The compound lead oxide sulfate PbSO4.PbO was prepared in our laboratory. The Thermal behavior of PbSO4 was studied using techniques of Thermogravimetry under air atmosphere from 25 to 1200°C. The identity of both compounds was confirmed by XRD technique. Results obtained using both techniques support same decomposition stages for this compound. The electron microscopic investigations are made by SEM and TEM. The compound is characterized by XRD and the purity was determined by analytical Methods. Also a series of thermogravimetric analysis is made and the ideal condition is determined to convert this compound to pure lead oxide.
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