747 research outputs found
New Pathophysiological Aspects of Growth and Prevention of Kidney Stones
Kidney stones probably grow during crystalluria by crystal sedimentation and aggregation (AGN) on stone surfaces. This process has to occur within urinary transit time (UT) through the kidney before crystals are washed out by diuresis. To get more information, we studied by spectrophotometry the formation and AGN of Ca oxalate (Ca Ox) crystals which were directly produced in urine of 30 stone patients and 30 controls by an oxalate (Ox) titration. Some tests were also performed after removing urinary macromolecules (UMs) by ultrafiltration. To induce rapid crystallization, high Ox additions (0.5â0.8âmM) were necessary. The most important finding was retardation of crystal AGN by UM. In urine of 63% of controls but only 33% of patients, no AGN was observed during an observation of 60 minutes (P < 0.05). Also growth and sedimentation rate of crystals were significantly reduced by UM. For stone metaphylaxis, especially for posttreatment residuals, avoiding dietary Ox excesses to prevent crystal formation in the kidney and increasing diuresis to wash out crystals before they aggregate are recommended
Adaptives Grundwassermanagement in urbanen Gebieten: Einfluss der OberflĂ€chengewĂ€sser-Grundwasser-Interaktion am Beispiel kĂŒnstlicher Grundwasseranreicherung sowie variabler In-/Exfiltration der Birs (Schweiz)
Zusammenfassung: Der Nutzungsdruck auf Grundwasserressourcen in intensiv genutzten Flussebenen wird zunehmend gröĂer. Ziel dieses Beitrages ist, anhand eines reprĂ€sentativen, instationĂ€ren Datensatzes eines urbanen Grundwassersystems (Unteres Birstal CH) aufzuzeigen, wie mit AnsĂ€tzen des adaptiven Grundwassermanagements die Voraussetzungen fĂŒr die nachhaltige Nutzung von Grundwasserressourcen geschaffen werden können. Mithilfe eines instationĂ€ren Grundwassermodells können spezifische Fragen der Fluss-Grundwasser-Interaktion und dem Betrieb kĂŒnstlicher Grundwasseranreicherung beantwortet werden. Die InstationaritĂ€t der Fluss-Grundwasser-Interaktion und eine damit zusammenhĂ€ngende Ănderung von In - und ExfiltrationsverhĂ€ltnissen konnte fĂŒr verschiedene Flussabschnitte ermittelt werden. Die Datenauswertung eines Jahrhunderthochwassers trug wesentlich zum VerstĂ€ndnis dieser Prozesse bei. Durch ein Experiment mit der lĂ€ngerfristigen AuĂerbetriebnahme einer kĂŒnstlichen Grundwasseranreicherung im Untersuchungsgebiet konnten die Auswirkungen von geplanten NutzungsĂ€nderungen abgeschĂ€tzt werden. Die Untersuchungen tragen zum ProzessverstĂ€ndnis des Grundwassersystems bei und liefern die Grundlage fĂŒr eine Diskussion ĂŒber lang-, mittel- und kurzfristige Ziele hinsichtlich der regionalen Bewirtschaftung urbaner Wasserressource
Observation of Ising-like critical fluctuations in frustrated Josephson junction arrays with modulated coupling energies
We report the results of ac sheet conductance measurements performed on fully
frustrated square arrays of Josephson junctions whose coupling energy is
periodically modulated in one of the principal lattice directions. Such systems
are predicted to exhibit two distinct transitions: a low-temperature Ising-like
transition triggered by the proliferation of domain walls and a
high-temperature transition driven by the vortex unbinding mechanism of the
Beresinskii-Kosterlitz-Thouless (BKT) theory. Both the superfluid and
dissipative components of the conductance are found to exhibit features which
unambiguously demonstrate the existence of a double transition whose properties
are consistent with the Ising-BKT scenario.Comment: To be published in Physica C (Proceedings of the 2nd European
Conference in School Format 'Vortex Matter in Superconductors'
From awareness raising to sustainable behaviour change in school: the WASH in school road map
Development organisations working in the WASH sector tend to focus on their preferred methodologies for Hygiene and Sanitation (H&S) promotion, while the sustainability of an intervention depends much more on how the methodology is implemented and whether an enabling environment is in place. In 2014, Caritas Switzerland in Kenya started a learning and critical review process on how to improve its WASH in school interventions to finally make the step from raising studentsâ awareness on good H&S practices to sustainable behaviour change. As a result of this process, a number of lessons on how to foster the enabling environment were learned, based on which the WASH in school road map was developed. This article presents, for each phase of the WASH in school road map, the main lessons learned and how they have been implemented in Kenya
Laser annealing of silicon on sapphire
Silicon-implanted silicon-on-sapphire wafers have been annealed by 50-ns pulses from a Q-switched Nd : YAG laser. The samples have been analyzed by channeling and by omega-scan x-ray double diffraction. After irradiation with pulses of a fluence of about 5 J cm^â2 the crystalline quality of the silicon layer is found to be better than in the as-grown state
Moisture and Seasonality Shifts Recorded in Holocene and Pleistocene Speleothems From Southeastern Arabia
The source and seasonality of rainfall in southern Arabia during the early- to mid-Holocene and preceding humid periods are controversial because fossil lacustrine sediments provide solely indirect information on the amount of rainfall. Hydrogen and oxygen isotope measurements on fluid inclusion water trapped in Holocene and Pleistocene stalagmites from Hoti Cave in Northern Oman are direct indicators of the isotopic composition of paleoprecipitation. Isotope values of fluid inclusions formed during peak interglacial periods plot along monsoonal water lines and are indicative of a southern monsoonal moisture source. The last monsoon-dominated period lasting from âŒ10,100 to 6,300 years before present was terminated within a few decades in southeastern Arabia. The subsequent reduction in rainfall amount and change from predominantly summer to predominantly winter rainfall had a profound impact on human communities living in this area and triggered migration from inland to coastal areas where resources were more abundant
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