Renal colic in a dialysis patient: a case of renal stone disease

Renal colic in a dialysis patient: a case of renal stone diseas

ON UKRAINIAN LABOR MARKET NEEDS IN MARKETERS

Asymmetric Incremental Sheet Forming (AISF) has been developed as a flexible process for low-volume production of sheet metal parts. In AISF, a part is obtained as the sum of localized plastic deformations produced by a simple forming tool that moves under CNC control. In spite of about 20 years of research and development, AISF has not had much industrial take-up yet. The main reason for this is that attempts to improve, among other limitations, the accuracy, speed and range of feasible geometries of the process by adapted process strategies has not brought about general solutions. This paper presents an overview of the current state of development of hybrid asymmetric incremental sheet forming processes at RWTH Aachen University. The goal of the development of hybrid ISF processes is to allow for a quantum leap of the capabilities of AISF in order to enable a broader industrial use of AISF. Two hybrid process variations of AISF are presented: stretch forming combined with ISF and laser-assisted AISF. It is shown that the combination of stretch forming and AISF can improve the time per part, sheet thickness distribution and accuracy of the final part. Laser-assisted AISF is shown to enable the flexible forming of non cold-workable materials such as magnesium and titanium alloys when the forming conditions are adapted to the temperature and strain rate dependent formability of the sheet metal. In addition, first results of the forming of hybrid aluminum-steel sheet metal are shown

Creating load-adapted mechanical joints between tubes and sheets by controlling the material flow under plastically unstable tube upsetting

Mechanical joining processes provide various advantages over conventional fusion welding of metallic components such as shorter cycle times, little or no heat input and reduced need for subsequent surface finishing operations. Several investigations in the past have shown that joints between tubes and sheets or plates can be manufactured by upsetting operations. Under axial compression, the tube develops a plastic instability in form of bulge. In-between two such bulges, a force and form fit to sheet material can be created. Previous work concentrated on forming fully developed bulges, i.e., at the end of the bulging process, both hinges of the bulge are in contact. This paper presents a numerical and experimental study aiming at optimizing the bulge shape to increase the bearable limit loads. Two new bulge designs are investigated, an 'arrow bulge' and a 'wave bulge'. The paper details the results of FE-simulations of the bulge shapes under bending and torsion loads. Forming tools were designed and both bulge shapes were produced experimentally. The results show that the material flow under compressive plastic instability can be controlled and that the resulting bulge shapes yield improved strength in various load cases

Compilation and Network Analyses of Cambrian Food Webs

A rich body of empirically grounded theory has developed about food webs—the networks of feeding relationships among species within habitats. However, detailed food-web data and analyses are lacking for ancient ecosystems, largely because of the low resolution of taxa coupled with uncertain and incomplete information about feeding interactions. These impediments appear insurmountable for most fossil assemblages; however, a few assemblages with excellent soft-body preservation across trophic levels are candidates for food-web data compilation and topological analysis. Here we present plausible, detailed food webs for the Chengjiang and Burgess Shale assemblages from the Cambrian Period. Analyses of degree distributions and other structural network properties, including sensitivity analyses of the effects of uncertainty associated with Cambrian diet designations, suggest that these early Paleozoic communities share remarkably similar topology with modern food webs. Observed regularities reflect a systematic dependence of structure on the numbers of taxa and links in a web. Most aspects of Cambrian food-web structure are well-characterized by a simple “niche model,” which was developed for modern food webs and takes into account this scale dependence. However, a few aspects of topology differ between the ancient and recent webs: longer path lengths between species and more species in feeding loops in the earlier Chengjiang web, and higher variability in the number of links per species for both Cambrian webs. Our results are relatively insensitive to the exclusion of low-certainty or random links. The many similarities between Cambrian and recent food webs point toward surprisingly strong and enduring constraints on the organization of complex feeding interactions among metazoan species. The few differences could reflect a transition to more strongly integrated and constrained trophic organization within ecosystems following the rapid diversification of species, body plans, and trophic roles during the Cambrian radiation. More research is needed to explore the generality of food-web structure through deep time and across habitats, especially to investigate potential mechanisms that could give rise to similar structure, as well as any differences

Functional diversity of marine ecosystems after the Late Permian mass extinction event

Article can be accessed from http://www.nature.com/ngeo/journal/v7/n3/full/ngeo2079.htmlThe Late Permian mass extinction event was the most severe such crisis of the past 500 million years and occurred during an episode of global warming. It is assumed to have had significant ecological impact, but its effects on marine ecosystem functioning are unknown and the patterns of marine recovery are debated. We analysed the fossil occurrences of all known Permian-Triassic benthic marine genera and assigned each to a functional group based on their inferred life habit. We show that despite the selective extinction of 62-74% of marine genera there was no significant loss of functional diversity at the global scale, and only one novel mode of life originated in the extinction aftermath. Early Triassic marine ecosystems were not as ecologically depauperate as widely assumed, which explains the absence of a Cambrian-style Triassic radiation in higher taxa. Functional diversity was, however, significantly reduced in particular regions and habitats, such as tropical reefs, and at these scales recovery varied spatially and temporally, probably driven by migration of surviving groups. Marine ecosystems did not return to their pre-extinction state, however, and radiation of previously subordinate groups such as motile, epifaunal grazers led to greater functional evenness by the Middle Triassic

Rise of the Earliest Tetrapods: An Early Devonian Origin from Marine Environment

Tetrapod fossil tracks are known from the Middle Devonian (Eifelian at ca. 397 million years ago - MYA), and their earliest bony remains from the Upper Devonian (Frasnian at 375–385 MYA). Tetrapods are now generally considered to have colonized land during the Carboniferous (i.e., after 359 MYA), which is considered to be one of the major events in the history of life. Our analysis on tetrapod evolution was performed using molecular data consisting of 13 proteins from 17 species and different paleontological data. The analysis on the molecular data was performed with the program TreeSAAP and the results were analyzed to see if they had implications on the paleontological data collected. The results have shown that tetrapods evolved from marine environments during times of higher oxygen levels. The change in environmental conditions played a major role in their evolution. According to our analysis this evolution occurred at about 397–416 MYA during the Early Devonian unlike previously thought. This idea is supported by various environmental factors such as sea levels and oxygen rate, and biotic factors such as biodiversity of arthropods and coral reefs. The molecular data also strongly supports lungfish as tetrapod's closest living relative

Post-processed data and graphical tools for a CONUS-wide eddy flux evapotranspiration dataset

Large sample datasets of in situ evapotranspiration (ET) measurements with well documented data provenance and quality assurance are critical for water management and many fields of earth science research. We present a post-processed ET oriented dataset at daily and monthly timesteps, from 161 stations, including 148 eddy covariance flux towers, that were chosen based on their data quality from nearly 350 stations across the contiguous United States. In addition to ET, the data includes energy and heat fluxes, meteorological measurements, and reference ET downloaded from gridMET for each flux station. Data processing techniques were conducted in a reproducible manner using open-source software. Most data initially came from the public AmeriFlux network, however, several different networks (e.g., the USDA-Agricultural Research Service) and university partners provided data that was not yet public. Initial half-hourly energy balance data were gap-filled and aggregated to daily frequency, and turbulent fluxes were corrected for energy balance closure error using the FLUXNET2015/ONEFlux energy balance ratio approach. Metadata, diagnostics of energy balance, and interactive graphs of time series data are included for each station. Although the dataset was developed primarily to benchmark satellite-based remote sensing ET models of the OpenET initiative, there are many other potential uses, such as validation for a range of regional hydrologic and atmospheric models

Post-processed data and graphical tools for a CONUS-wide eddy flux evapotranspiration dataset

Large sample datasets of in situ evapotranspiration (ET) measurements with well documented data provenance and quality assurance are critical for water management and many fields of earth science research. We present a post-processed ET oriented dataset at daily and monthly timesteps, from 161 stations, including 148 eddy covariance flux towers, that were chosen based on their data quality from nearly 350 stations across the contiguous United States. In addition to ET, the data includes energy and heat fluxes, meteorological measurements, and reference ET downloaded from grid- MET for each flux station. Data processing techniques were conducted in a reproducible manner using open-source soft- ware. Most data initially came from the public AmeriFlux network, however, several different networks (e.g., the USDA- Agricultural Research Service) and university partners pro- vided data that was not yet public. Initial half-hourly energy balance data were gap-filled and aggregated to daily frequency, and turbulent fluxes were corrected for energy balance closure error using the FLUXNET2015/ONEFlux energy balance ratio approach. Metadata, diagnostics of energy balance, and interactive graphs of time series data are included for each station. Although the dataset was developed primarily to benchmark satellite-based remote sensing ET models of the OpenET initiative, there are many other potential uses, such as validation for a range of regional hydrologic and atmospheric models