500 research outputs found
Physics and Chemistry of Dissolution on Subaerialy Exposed Soluble Rocks by Flowing Water Films
The basic process active in the formation of subaerial features on karst rocks is chemical dissolution of limestone or gypsum by water films flowing on the rock surface. The dissolution rates of limestone and gypsum into thin films of water in laminar flow are given by F = α(ceq-c), where (ceq-c) is the difference of the actual concentration c in the water film and the equilibrium concentration ceq with respect to the corresponding mineral. Whereas for gypsum α is determined by molecular diffusion the situation is more complex for limestone. Experiments are presented, which show that for high undersaturation, c<0.3ceq, the rate law is F = α( 0.3ceq-c) ,and α becomes higher by about a factor of ten than for the rates at c>0.3ceq. These rate laws are used to calculate denudation rates on bare rock surfaces exposed to rainfall with differing intensity. The estimations are in reasonable agreement to field data. Starting from the experiments on the formation of Rillenkarren on gypsum performed by Glew and Ford (1980), we suggest a new relation between their length from the crest to the “Ausgleichsfläche” and the inclination of the rock surface. This is also applied to field data of Rillenkarren on limestone provided by J. Lundberg and A. Gines. In view of the many parameters influencing the formation of Rillenkarren these correlations can be considered as satisfactory
Different Dynamics and Entropy Rates in Quantum-Thermodynamics
Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.Different dynamics of the non-equilibrium canonical density operator, such as Canonical Dynamics, Linear Projection Dynamics, Generalized Robertson Dynamics, and Contact Time Dynamics, especially for time dependent work variables are derived. For two discrete systems in contact the rate of entropy is non-negative, if the contact time is short, and if one of the two discrete systems is in equilibrium and the compound system composed of both is isolated. The contact temperature is identified with one of the Lagrange parameters of the non-equilibrium canonical density operator of the compound system
Validity and responsiveness of the EQ-5D in assessing and valuing health status in patients with somatoform disorders
Background: The EQ-5D is a generic questionnaire providing a preference-based index score applicable to cost-utility analysis. This is the first study to validate the EQ-5D in patients with somatoform disorders. Methods: Data of the EQ-5D descriptive system, the British and the German EQ-5D index and the EQ Visual Analogue Scale, the Patient Health Questionnaire 15, the Patient Health Questionnaire 9, the Whiteley Index 7 and the Short Form 36 were collected from 294 patients at baseline, 244 at 6 months and 256 at 12 months after baseline. The discriminative ability of the EQ-5D was evaluated by comparison with a general population sample and by the ability to distinguish between different symptom severities. Convergent validity was analysed by assessing associations between the EQ-5D and the other instruments. Responsiveness was evaluated by analysing the effects on scores between two measurements in groups of patients reporting worse, same or better health. The Bonferroni correction was employed. Results: For all items of the EQ-5D except ‘self-care’, patients with somatoform disorders reported more problems than the general population. The EQ-5D showed discriminative ability in patients with different symptom severities. For nearly all reference instruments there were significant differences in mean scores between respondents with and without problems in the various EQ-5D items and strong correlations with the EQ Visual Analogue Scale and the EQ-5D index scores. Evidence for the responsiveness of the EQ-5D could only be found for patients with better health; effects were medium at the utmost. Conclusions: The EQ-5D showed a considerable validity and a limited responsiveness in patients with somatoform disorders. Trial registration: Current Controlled Trials ISRCTN5528079
Evolution of caves in porous limestone by mixing corrosion: A model approach.
When water from the surface, e.g. from a lake, fl ows down through porous carbonate rocks, through a region with high hydraulic conductivity and encounters the water table of a phreatic aquifer, both waters mix by diffusion along their boundary. In a carbonate aquifer, where both surface and phreatic waters are saturated with respect to calcite, mixing corrosion causes renewed dissolution capacity Δceq of the carbonate rock in the diffusion-mixing zone, extending from the boundary separating the phreatic water from the surface water encountering it. A numerical model is presented from which the initial change of porosity in such a diffusion-mixing zone is obtained. The initial change of porosity can be calculated from the local distribution of the mixing ratio, and the second derivative of Δceq with respect to m. m(x,y)is the spatial distribution of the mixing ratio m= Vsurf /(Vsuf+ Vprh), where the V’s assign the corresponding volumes of surface and phreatic water. The second derivative has been calculated for three geochemical scenarios with differing CO2-concentrations of surface and phreatic water by the use of PHREEQC-2. The spatial distribution m(x,y) is obtained by using MODFLOW and MT3DMS in a modelling domain with constant hydraulic conductivity for various fl ow velocities of the phreatic aquifer. The time scale of cave evolution is estimated from the results. Passages of dimensions of about one metre in width and several 10 cm in height, extending in length along the boundary line, where surface and phreatic waters meet, can be created in time scales of 10 000 years. These caves are horizontal with blind ending passages and closely resemble the isolated caves observed in Central West Florida. </p
Economics of medically unexplained symptoms: a systematic review of the literature
Objective: To review cost-of-illness studies (COI) and economic evaluations (EE) conducted for medically unexplained symptoms and to analyze their methods and results. Methods: We searched the databases PubMed, PsycINFO and National Health Service Economic Evaluations Database of the University of York. Cost data were inflated to 2006 using country-specific gross domestic product inflators and converted to 2006 USD purchasing power parities. Results: We identified 5 COI and 8 EE, of which 6 were cost-minimization analyses and 2 were cost-effectiveness analyses. All studies used patient level data collected between 1980 and 2004 and were predominantly conducted in the USA (n = 10). COI found annual excess health care costs of somatizing patients between 432 and 5,353 USD in 2006 values. Indirect costs were estimated by only one EE and added up to about 18,000 USD per year. In EE, educational interventions for physicians as well as cognitive-behavioral therapy approaches for patients were evaluated. For both types of interventions, effectiveness
was either shown within EE or by previous studies
Zurich Consensus: German Expert Opinion on the St. Gallen Votes on 15 March 2009 (11th International Conference at St. Gallen: Primary Therapy of Early Breast Cancer)
A German working group of 23 breast cancer experts discussed the results from the vote at this year's St. Gallen Consensus Conference on Primary Therapy for Early Breast Cancer ( March 11-14, 2009) and came up with some concrete recommendations for day-to-day therapeutic decisions in Germany. Due the fact that the concept of the St. Gallen Consensus Conference merely allows for a minimal consensus, the objective of the working group was to provide practice-related recommendations for day-to-day clinical decisions in Germany. One area of emphasis at St. Gallen was tumor biology as a starting point for reaching individual therapeutic decisions. Intensive discussion was necessary with respect to the clinical relevance of predictive and prognostic factors. A new addition to the area of systemic therapy was a first-ever discussion of the adjuvant administration of bisphosponates and the fact that therapy with trastuzumab in HER2 overexpressing breast cancer has been defined as the standard for neoadjuvant therapy. The value of taxanes as a component of (neo) adjuvant chemotherapy as well as the value of aromatase inhibitors for the endocrine adjuvant treatment of postmenopausal patients were affirmed
Panta Rhei: Movement Change of Tschadinhorn Rock Glacier (Hohe Tauern Range, Austria), 1954–2017
U radu se prikazuje rekonstrukcija kinematike kamenog glečera Tschadinhorn upotrebom viševremenskih konvencionalnih (mjernih) fotografija snimljenih iz zraka (1954–2015) i dodatnih nemjernih fotografija snimljenih iz zraka (2016, 2017) bespilotnim letjelicama (unmanned aerial vehicles – UAV). Letjelica s rotirajućim krilima (hexacopter twinHEX v.3.0) upotrebljena je 2016. godine, a letjelica s nepokretnim krilima (QuestUAV) upotrebljena je 2017. Povijesni slikovni podaci dobiveni su od Austrijskog federalnog ureda za metrologiju i izmjeru (Bundesamt für Eich- und Vermessungswesen – BEV). Za svako su razdoblje izračunani digitalni ortofoto (DOP) i digitalni model reljefa (digital relief model – DTM). Precizno georeferenciranje slikovnih podataka provedeno je u austrijskom koordinatnom sustavu Gauss- Krüger M31 upotrebom aerotriangulacija (AT) dobivenih od BEV-a i dodatnim kontrolnim točkama na tlu (ground control point – GCP) geodetski izmjerenih tijekom obaju izmjera bespilotnim letjelicama. Analiza otkrivanja promjena rezultirala je viševremenskim dvodimenzionalnim poljem brzina kretanja. Nakon toga, podaci su sređeni kako bi se dobio jednostavniji grafički prikaz brzine koji jasno pokazuje razvoj brzine kretanja kamenog glečera. Najveća prosječna godišnja brzina kretanja od 3,28 metra u godini dobivena je u razdoblju 2014– 2015, dok je najmanja godišnja brzina od 0,16 metra u godini opažena u razdoblju 1969–1974. Na grafičkom prikazu brzine također se vidi da je razdoblje 1954–2009 bilo karakterizirano uglavnom umjerenom aktivnošću (0,16 – 0,79 metra u godini) te da od 2009. prevladavaju mnogo veće brzine kretanja. Trenutačna vrijednost za 2016–2017 iznosi 1,92 metra u godini.In this paper we present a reconstruction of the kinematics of the Tschadinhorn rock glacier using multi-temporal conventional (metric) aerial photographs (1954–2015) and additional non-metric aerial photographs (2016, 2017) taken with in-house unmanned aerial vehicles (UAVs). A rotary-wing aircraft (hexacopter twinHEX v.3.0) was used in 2016 and a fixed-wing aircraft (QuestUAV) in 2017. The historical image data was acquired from the Austrian Federal Office of Metrology and Surveying (BEV). Both a digital orthophoto (DOP) and a digital terrain model (DTM) were computed for each given epoch. Precise georeferencing of the image data was carried out in the Austrian Gauss-Krüger M31 coordinate system using available aerotriangulations (ATs) of BEV and additional ground control points (GCPs) measured geodetically during both UAV campaigns. Change detection analysis provided multi-temporal 2D flow velocity fields. Subsequently, these data were collated to produce a simpler velocity graph showing clearly the temporal evolution of the flow velocity of Tschadinhorn rock glacier: A maximum mean annual flow velocity of 3.28 m/year was obtained for 2014–2015, while the lowest annual flow velocity of 0.16 m/year was observed for 1969–1974. The velocity graph also revealed that 1954–2009 was characterized by generally moderate activity (0.16 – 0.79 m/year) and that much higher flow velocities have prevailed since 2009. The present value for 2016–2017 is 1.92 m/year
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