Detection of urinary stones at reduced radiation exposure: a phantom study comparing computed radiography and a low-dose digital radiography linear slit scanning system

OBJECTIVE: In this experimental study we assessed the diagnostic performance of digital linear slit scanning radiography compared with computed radiography (CR) for the detection of urinary calculi in an anthropomorphic phantom imitating patients weighing approximately 58-88 kg. CONCLUSION: Compared with CR, linear slit scanning radiography is superior for the detection of urinary stones and may be used for pretreatment localization and follow-up at a lower patient exposure.

Rolling stones and tree rings: A state of research on dendrogeomorphic reconstructions of rockfall

This progress report focuses on the contribution of tree-ring series to rockfall research and on recent development and challenges in the field. Dendrogeomorphic techniques have been used extensively since the early 2000s and several approaches have been developed to extract rockfall signals from tree-ring records of conifer trees. The reconstruction of rockfall chronologies has been hampered in the past by sample sizes that decrease as one goes back in time, as well as by a paucity of studies that include broadleaved tree species, which are in fact quite common in rockfall-prone environments. In this report, we propose a new approach considering impact probability and quantification of uncertainty in the reconstruction of rockfall time series as well as a quantitative estimate of presumably missed events. In addition, we outline new approaches and future perspectives for the inclusion of woody vegetation in hazard assessment procedures, and end with future thematic perspectives.

Volcanic forcing for climate modeling: a new microphysics-based data set covering years 1600–present

As the understanding and representation of the impacts of volcanic eruptions on climate have improved in the last decades, uncertainties in the stratospheric aerosol forcing from large eruptions are now linked not only to visible optical depth estimates on a global scale but also to details on the size, latitude and altitude distributions of the stratospheric aerosols. Based on our understanding of these uncertainties, we propose a new model-based approach to generating a volcanic forcing for general circulation model (GCM) and chemistry–climate model (CCM) simulations. This new volcanic forcing, covering the 1600–present period, uses an aerosol microphysical model to provide a realistic, physically consistent treatment of the stratospheric sulfate aerosols. Twenty-six eruptions were modeled individually using the latest available ice cores aerosol mass estimates and historical data on the latitude and date of eruptions. The evolution of aerosol spatial and size distribution after the sulfur dioxide discharge are hence characterized for each volcanic eruption. Large variations are seen in hemispheric partitioning and size distributions in relation to location/date of eruptions and injected SO2 masses. Results for recent eruptions show reasonable agreement with observations. By providing these new estimates of spatial distributions of shortwave and long-wave radiative perturbations, this volcanic forcing may help to better constrain the climate model responses to volcanic eruptions in the 1600–present period. The final data set consists of 3-D values (with constant longitude) of spectrally resolved extinction coefficients, single scattering albedos and asymmetry factors calculated for different wavelength bands upon request. Surface area densities for heterogeneous chemistry are also provided.

Optimization of extracorporeal shock wave lithotripsy delivery rates achieves excellent outcomes in ureteral stones. Results of a prospective, randomized trial

PURPOSE Management of ureteral stones remains controversial. To determine whether optimizing extracorporeal shock wave lithotripsy (ESWL) delivery rates improves treatment of solitary ureteral stones, we compared outcomes of two SW delivery rates in a prospective, randomized trial. MATERIALS AND METHODS From July 2010 to October 2012, 254 consecutive patients were randomized to undergo ESWL at SW delivery rates of either 60 pulses (n=130) or 90 pulses (n=124) per min. The primary endpoint was stone-free rate at 3-month follow-up. Secondary endpoints included stone disintegration, treatment time, complications, and the rate of secondary treatments. Descriptive statistics were used to compare endpoints between the two groups. Adjusted odds ratios and 95% confidence intervals were calculated to assess predictors of success. RESULTS The stone-free rate at 3 months was significantly higher in patients who underwent ESWL at a SW delivery rate of 90 pulses per min than in those receiving 60 pulses (91% vs. 80%, p=0.01). Patients with proximal and mid-ureter stones, but not those with distal ureter stones, accounted for the observed difference (100% vs. 83%; p=0.005; 96% vs. 73%, p=0.03; and 81% vs. 80%, p=0.9, respectively). Treatment time, complications, and the rate of secondary treatments were comparable between the two groups. In multivariable analysis, SW delivery rate of 90 pulses per min, proximal stone location, stone density, stone size and the absence of an indwelling JJ stent were independent predictors of success. CONCLUSIONS Optimization of ESWL delivery rates can achieve excellent results for ureteral stones.

Oxygen isotopes of lake marl at Gerzensee and Leysin (Switzerland), covering the Younger Dryas and two minor oscillations, and their correlation to the GRIP ice core

The ratio of oxygen isotopes is a temperature proxy both in precipitation and in the calcite of lacustrine sediments. The very similar oxygen-isotope records from Greenland ice cores and European lake sediments during the Last Glacial Termination suggest that the drastic climatic changes occurred quasi-simultaneously on an extra-regional, probably hemispheric scale. In order to study temporal relations of the different parameters recorded in lake sediments, for example biotic response times to rapid climatic changes, a precise chronology is required. In unlaminated lake sediments there is not yet available a method to provide a high-resolution chronology, especially for periods with radiocarbon plateaux. Alternatively, an indirect time scale can be constructed by linking the lake stratigraphy with other well-dated climate records. New oxygen-isotope records from Gerzensee and Leysin, with an estimated sampling resolution of between 15 and 40 years, match the Greenlandic isotope record in many details. Under the assumption that the main variations in temperature and thus in oxygen isotopes occurred about simultaneously in Greenland and Switzerland, we have assigned a time scale to the lake sediments of Gerzensee and Leysin by wiggle-matching their stable-isotope records with those of Greenland ice cores, which are among the best dated climatic archives. We estimate a precision of 20 to 100 years during the Last Glacial Termination.

Dust record from the EPICA Dome C ice core, Antarctica, covering 0 to 800 kyr BP

Dust can affect the radiative balance of the atmosphere by absorbing or reflecting incoming solar radiation and it can be a source of micronutrients, such as iron, to the ocean. It has been suggested that production, transport, and deposition of dust is influenced by climatic changes on glacial-interglacial timescales. Here we present a high-resolution aeolian dust record from the EPICA Dome C ice core in East Antarctica, which provides an undisturbed climate sequence over the last eight climatic cycles. We find that there is a significant correlation between dust flux and temperature records during glacial periods that is absent during interglacial periods. Our data suggests that dust flux is increasingly correlated with Antarctic temperature as climate becomes colder. We interpret this as progressive coupling of Antarctic and lower latitudes climate. Limited changes in glacial-interglacial atmospheric transport time Mahowald et al. (1999, doi:10.1029/1999JD900084), Jouzel et al. (2007, doi:10.1126/science.1141038), and Werner et al. (2002, doi:10.1029/2002JD002365) suggest that the sources and lifetime of dust are the major factors controlling the high glacial dust input. We propose that the observed ~25-fold increase in glacial dust flux over all eight glacial periods can be attributed to a strengthening of South American dust sources, together with a longer atmospheric dust particle life-time in the upper troposphere resulting from a reduced hydrological cycle during the ice ages.

Pedogeomorphology, geochronology and paleobotany of soil profiles obtained in the Kyichu River catchment, sourthern Tibet

Results of pedogeomorphological, geochronological and paleobotanical investigations are presented covering the last ca. 4,000 years. The study sites are located in the heavily degraded Kyichu River catchment around Lhasa at 3,600-4,600 m a.s.l. Repeatedly, colluvial sediments have been recorded overlying paleosols. These deposits can be divided into i) coarse-grained sediments with a high proportion of stones and boulders originating from alluvial fans and debris flows, ii) matrix supported sediments with some stones and boulders originating from mudflows or combined colluvial processes such as hillwash plus rock fall, and iii) fine-grained sediments originating from hill wash. The IRSL multi-level dating of profile QUG 1 points to a short-time colluvial sedimentation between 1.0 ± 0.1 and 0.8 ± 0.1 ka. In contrast, dated paleosols of profile GAR 1 (7,908 ± 99 and 3,668 ± 57 BP) encompass a first colluvial episode. Here, the upper colluvial sedimentation took place during several periods between 2.6 ± 0.3 and 0.4 ± 0.1 ka. For the first time in Tibet, a systematic extraction, determination and dating of charcoals from buried paleosols was conducted. The charcoals confirm the Late Holocene presence of juniper forests or woodlands in a now treeless, barren environment. A pollen diagram from Lhasa shows a distinct decline of pollen of the Jumperus-type around 4,140 ± 50 BP, which is interpreted as indicating a clearing of forests on the adjacent slopes. It is assumed that the environmental changes from forests to desertic rangelands since ca. 4,000 BP have been at least reinforced by humans.

Natural remanent magnetization (NRM) from ODP Site 1263 covering magnetochron C20r and C21n and high-resolution bulk carbon isotope (d13C) records from Sites 702 and 1263

To explore cause and consequences of past climate change, very accurate age models such as those provided by the astronomical timescale (ATS) are needed. Beyond 40 million years the accuracy of the ATS critically depends on the correctness of orbital models and radioisotopic dating techniques. Discrepancies in the age dating of sedimentary successions and the lack of suitable records spanning the middle Eocene have prevented development of a continuous astronomically calibrated geological timescale for the entire Cenozoic Era. We now solve this problem by constructing an independent astrochronological stratigraphy based on Earth's stable 405 kyr eccentricity cycle between 41 and 48 million years ago (Ma) with new data from deep-sea sedimentary sequences in the South Atlantic Ocean. This new link completes the Paleogene astronomical timescale and confirms the intercalibration of radioisotopic and astronomical dating methods back through the Paleocene-Eocene Thermal Maximum (PETM, 55.930 Ma) and the Cretaceous-Paleogene boundary (66.022 Ma). Coupling of the Paleogene 405 kyr cyclostratigraphic frameworks across the middle Eocene further paves the way for extending the ATS into the Mesozoic.