An application of the Bivariate Generalized Pareto Distribution for the probabilities of low flow extremes estimation

International audienceThe two-dimensional Bivariate Generalized Pareto Distribution (BGPD) of Tajvidi (1996) is applied in order to estimate the extreme values of the low flow deficit amounts and durations probabilities. Eight parameters BGPD depends on two one-dimensional distributions ? Univariate Generalized Pareto Distributions (UGPDs). Each of these three parameter UGPDs describes the probability of one of low flow indices. To fit BGPD into observed data a three steps method of estimation is proposed: (1) For a given shift parameter of each UGPD two others are estimated by the maximum likelihood method. (2) For given shifts and the UGPD parameters estimated in the first step the remaining ones, connected to the bivariate distribution function formula, are also estimated by the maximum likelihood method. (3) The best shift pair is chosen by maximization of the correlation coefficient of the estimated BGPD. The results are applied to statistical description of the low flow index extremes behaviour at four different catchments profiles. To extract the low flow time series data the standard constant threshold level method is applied. Finally the estimated probabilities are compared to the Zelenhasic and Salvai (1987) model

Mistranslation and its control by tRNA synthetases

Aminoacyl tRNA synthetases are ancient proteins that interpret the genetic material in all life forms. They are thought to have appeared during the transition from the RNA world to the theatre of proteins. During translation, they establish the rules of the genetic code, whereby each amino acid is attached to a tRNA that is cognate to the amino acid. Mistranslation occurs when an amino acid is attached to the wrong tRNA and subsequently is misplaced in a nascent protein. Mistranslation can be toxic to bacteria and mammalian cells, and can lead to heritable mutations. The great challenge for nature appears to be serine-for-alanine mistranslation, where even small amounts of this mistranslation cause severe neuropathologies in the mouse. To minimize serine-for-alanine mistranslation, powerful selective pressures developed to prevent mistranslation through a special editing activity imbedded within alanyl-tRNA synthetases (AlaRSs). However, serine-for-alanine mistranslation is so challenging that a separate, genome-encoded fragment of the editing domain of AlaRS is distributed throughout the Tree of Life to redundantly prevent serine-to-alanine mistranslation. Detailed X-ray structural and functional analysis shed light on why serine-for-alanine mistranslation is a universal problem, and on the selective pressures that engendered the appearance of AlaXps at the base of the Tree of Life

Design definition study of a NASA/Navy lift/cruise fan technology V/STOL airplane: Risk assessment addendum to the final report

An assessment of risk, in terms of delivery delays, cost overrun, and performance achievement, associated with the V/STOL technology airplane is presented. The risk is discussed in terms of weight, structure, aerodynamics, propulsion, mechanical drive, and flight controls. The analysis ensures that risks associated with the design and development of the airplane will be eliminated in the course of the program and a useful technology airplane that meets the predicted cost, schedule, and performance can be produced

LIS–lnterlink—connecting laboratory information systems to remote primary health–care centres via the Internet

A pilot study was performed to evaluate the feasibility of using the Internet to securely deliver patient laboratory results, and the system has subsequently gone into routine use in Poland. The system went from design to pilot and then to live implementation within a four-month period, resulting in the LIS-Interlink software product. Test results are retrieved at regular intervals from the BioLinkTM LIS (Laboratory Information System), encrypted and transferred to a secure area on the Web server. The primary health-care centres dial into the Internet using a local-cell service provided by Polish Telecom (TP), obtain a TCP/IP address using the TP DHCP server, and perform HTTP ‘get’ and ‘post’ operations to obtain the files by secure handshaking. The data are then automatically inserted into a local SQL database (with optional printing of incoming reports)for cumulative reporting and searching functions. The local database is fully multi-user and can be accessed from different clinics within the centres by a variety of networking protocols

Poliovirus adsorption by soil particles in seawater

This investigation was initiated in an attempt to delineate some factors affecting the adsorption of poliovirus to soil particles in seawater. The results could have significance in the development of assay procedures for viral contaminants in natural waters. A sample of marine sediment, obtained from an estuary near Purdy, Washington, was characterized by X-ray diffraction and shown to consist primarily of 2:1 type mineralogical components. When poliovirus type I was mixed with the marine sediment, or with purified montmorillonite and kaolinite suspensions containing electrolyte, the virus was removed from the supernatant fluid of samples subjected to low-speed centrifugation. Fetal bovine serum, in concentrations of 0.2% to 2%, prevented and reversed adsorption of the virus to the clay fraction of the marine sediment. A serum concentration of 0.02% decreased virus adsorption but 0.002% serum had no effect. Hydrogen ion concentrations, in the range of pH 5 to 9, had no significant effect on the amount of virus adsorbed by marine sediment suspended in seawater. Adsorption of virus by the clay fractions of montmorillonite and kaolinite was more efficient than adsorption by the silt fractions, although significant removal of virus by the larger particles did occur. Adsorption of up to 60% of the virus occurred at clay concentrations as low as 1 mg/liter, while clay concentrations of 50 mg/liter resulted in almost complete removal of the virus from the supernatant fluid. The virus did not adsorb to the clays in a deionized water medium, but when suspended in seawater diluted to salinities as low as 0.1%, or in deionized water containing 10⁻⁵M AlCl₃, adsorption did occur. Clays of the 2:1 type required higher concentrations of electrolyte than did the 1:1 type kaolinite to adsorb virus. Lower concentrations of MgCl₂ than NaCl resulted in adsorption. Attempts to release virus adsorbed to kaolinite, by suspending in a medium of lower electrolyte concentration, were not successful. Limited electron microscope studies did not unequivocally establish the adsorption site of virus to kaolinite crystals, but structural defects of the crystals were observed which may be important in the adsorption phenomenon. The mechanism of adsorption has not been established but a flocculation type is suggested

Sexual dimorphism, asymmetry, and the effect of reproduction on pelvis bone in the bank vole, Myodesglareolus

Sexual dimorphism in anatomical traits has been widely studied in animals. Although pelvis dimorphism was mostly studied in humans, it occurs also in many other mammalian species. Here, we investigated sexual dimorphism in the pelvis of the bank vole Myodes glareolus using individuals with known sex and reproductive status of females (parous vs nulliparous). The analyses revealed that the size and shape of pelvis differed significantly between sexes, as well as between nulliparous and parous females. In comparison with males, females had a significantly longer pelvis and pubis bones and a longer obturator foramen length, but a smaller pubis width. Interestingly, the difference between parous and nulliparous females resembles that between females and males: parous females had bigger pelvis, which probably resulted from changes during pregnancy and after birth. Left bones were on average larger than right ones, but the magnitude of directional asymmetry was not different between sex and reproduction group. Moreover, we noticed that fluctuating asymmetry of pelvis and pubis length was higher in females than in males and higher in parous than in nulliparous females, what is presumably associated with locomotor performance. A discriminant function analysis performed for the four bone size traits showed that the traits can be effectively used for a nearly perfect recognition of sexes and also a quite reliable recognition of the reproductive status of females

Architecture of a Silicon Strip Beam Position Monitor

A collaboration between Fermilab and the Institute for High Energy Physics (IHEP), Beijing, has developed a beam position monitor for the IHEP test beam facility. This telescope is based on 5 stations of silicon strip detectors having a pitch of 60 microns. The total active area of each layer of the detector is about 12x10 cm2. Readout of the strips is provided through the use of VA1` ASICs mounted on custom hybrid printed circuit boards and interfaced to Adapter Cards via copper-over-kapton flexible circuits. The Adapter Cards amplify and level-shift the signal for input to the Fermilab CAPTAN data acquisition nodes for data readout and channel configuration. These nodes deliver readout and temperature data from triggered events to an analysis computer over gigabit Ethernet links.Comment: Submitted to TWEPP 201

Effect of resonant magnetic perturbations on low collisionality discharges in MAST and a comparison with ASDEX Upgrade

Sustained ELM mitigation has been achieved on MAST and AUG using RMPs with a range of toroidal mode numbers over a wide region of low to medium collisionality discharges. The ELM energy loss and peak heat loads at the divertor targets have been reduced. The ELM mitigation phase is typically associated with a drop in plasma density and overall stored energy. In one particular scenario on MAST, by carefully adjusting the fuelling it has been possible to counteract the drop in density and to produce plasmas with mitigated ELMs, reduced peak divertor heat flux and with minimal degradation in pedestal height and confined energy. While the applied resonant magnetic perturbation field can be a good indicator for the onset of ELM mitigation on MAST and AUG there are some cases where this is not the case and which clearly emphasise the need to take into account the plasma response to the applied perturbations. The plasma response calculations show that the increase in ELM frequency is correlated with the size of the edge peeling-tearing like response of the plasma and the distortions of the plasma boundary in the X-point region.Comment: 31 pages, 28 figures. This is an author-created, un-copyedited version of an article submitted for publication in Nuclear Fusion. IoP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from i