71 research outputs found

    Water balance of selected floodplain lake basins in the Middle Bug River valley

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    This study is the first attempt in the literature on the subject of comparing water balance components for floodplain lake basins, depending on the type of a lake connection to the parent river. Research was carried out in the Bug River valley in 2007–2011 water years. Four types of connections were distinguished in the area under study. Simple water balance equation could only be used with regard to the lakes connected to the main river via the upstream crevasses. Detailed and individual water balance equations were developed with reference to the other types of lakes. Water gains and losses varied significantly in the lakes under study. Values of horizontal water balance components (inflow and outflow) of the floodplain lake in Wola Uhruska considerably prevailed over the vertical ones (precipitation and evaporation). Inflow of the Bug River waters was diverse during the time period under study and amounted from 600 000 to 2 200 000 m<sup>3</sup> yr<sup>−1</sup>. Volumes of precipitation and evaporation were rather stable and amounted to approx. 30 000 m<sup>3</sup> yr<sup>−1</sup>. The lowest disparity between horizontal and vertical water balance components was observed in the inter-levee lake. Both upstream inflow of rivers water and outflow from the lake (ranged from 0 in 2008 to 35 000 m<sup>3</sup> yr<sup>−1</sup> in 2009) were usually an order of magnitude higher than precipitation and evaporation from the lake surface (700–800 m<sup>3</sup> yr<sup>&minus;1</sup>). Study showed that the values and the proportion between aforementioned vertical and horizontal water balance elements were determined by the type of a lake connection to the Bug River. Storage volume showed no relationship to the type of connection, but resulted from individual features of the lakes (location within the valley, precipitation and evaporation volume, difference between water inflow and outflow)

    Exploring emergence in interconnected ferromagnetic nanoring arrays

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    Emergent interactions in periodic, artificial ferromagnetic nanostructures is well explored for magnetic systems such as artificial spin ices (ASI). This work presents a novel approach of an interconnected array of ferromagnetic nanorings to harness emergence in a dynamic system for functionality. Magnetic nanorings have two preferred configurations of magnetisation – ‘vortex’ that contains no domain walls (DWs) and ‘onion’ state with two DWs. In-plane applied rotating fields move DWs around a ring. The junction between interconnected rings presents a pinning potential that must be overcome to continue DW motion. In an ensemble, such as an array of interconnected rings, a sufficiently high field gives unimpeded DW motion. Under a sufficiently low field, no DWs de-pin. Both conserve DW population. Between these limits, de-pinning is probabilistic and field dependent. When one DW in an ‘onion’ state is pinned and the other de-pins, annihilation of DWs will occur and rings convert from ‘onion’ to ‘vortex’. Micromagnetic modelling also shows a DW de-pinning from a junction adjacent to a ‘vortex’ ring repopulates it with DWs. Analytical modelling of DW population revealed an equilibrium that varies non- monotonically with de-pinning probability and varies with array size and geometry. Polarised neutron reflectometry (PNR) and MOKE magnetometry measured arrays of permalloy nanorings. Magnetisation as a function of applied rotating field strength confirmed a non-monotonic response. Magnetic force microscopy (MFM) and photoemission electron microscopy (PEEM) allowed direct observation of DW configurations, revealing: highly ordered arrangements of ‘onion’ states at saturation; minor changes in DW population with low and high strength rotating fields; DW loss and breakdown in long-range order with intermediate fields. Imaging showed junctions produce behaviour analogous to emergent vertex configurations in ASIs. Interconnected nanoring arrays show good candidacy for novel computing architectures, such as reservoir computing, given their dynamic tuneability, non-linear response to an external stimulus, scalability, fading memory and repeatability

    The Redox Imbalance and the Reduction of Contractile Protein Content in Rat Hearts Administered with L-Thyroxine and Doxorubicin

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    Oxidative stress and disorders in calcium balance play a crucial role in the doxorubicin-induced cardiotoxicity. Moreover, many cardiotoxic targets of doxorubicin are regulated by iodothyronine hormones. The aim of the study was to evaluate effects of tetraiodothyronine (0.2, 2 mg/L) on oxidative stress in the cardiac muscle as well as contractility and cardiomyocyte damage markers in rats receiving doxorubicin (1.5 mg/kg) once a week for ten weeks. Doxorubicin was administered alone (DOX) or together with a lower (0.2T4 + DOX) and higher dose of tetraiodothyronine (2T4 + DOX). Two groups received only tetraiodothyronine (0.2T4, 2T4). Coadministration of tetraiodothyronine and doxorubicin increased the level of lipid peroxidation products and reduced RyR2 level when compared to untreated control and group exposed exclusively to doxorubicin. Insignificant differences in SERCA2 and occasional histological changes were observed. In conclusion, an increase of tetraiodothyronine level may be an additional risk factor of redox imbalance and RyR2 reduction in anthracycline cardiotoxicity

    Tirapazamine-Doxorubicin Interaction Referring to Heart Oxidative Stress and Ca2+ Balance Protein Levels

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    Doxorubicin (DOX) causes long-term cardiomyopathy that is dependent on oxidative stress and contractility disorders. Tirapazamine (TP), an experimental adjuvant drug, passes the same red-ox transformation as DOX. The aim of the study was to evaluate an effect of tirapazamine on oxidative stress, contractile protein level, and cardiomyocyte necrosis in rats administered doxorubicin. Rats were intraperitoneally injected six times once a week with tirapazamine in two doses, 5 (5TP) and 10 mg/kg (10TP), while doxorubicin was administered in dose 1.8 mg/kg (DOX). Subsequent two groups received both drugs simultaneously (5TP+DOX and 10TP+DOX). Tirapazamine reduced heart lipid peroxidation and normalised RyR2 protein level altered by doxorubicin. There were no significant changes in GSH/GSSG ratio, total glutathione, cTnI, AST, and SERCA2 level between DOX and TP+DOX groups. Cardiomyocyte necrosis was observed in groups 10TP and 10TP+DOX

    Toward Chirality‐Encoded Domain Wall Logic

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    Nonvolatile logic networks based on spintronic and nanomagnetic technologies have the potential to create high‐speed, ultralow power computational architectures. This article explores the feasibility of “chirality‐encoded domain wall logic,” a nanomagnetic logic architecture where data are encoded by the chiral structures of mobile domain walls in networks of ferromagnetic nanowires and processed by the chiral structures' interactions with geometric features of the networks. High‐resolution magnetic imaging is used to test two critical functionalities: the inversion of domain wall chirality at tailored artificial defect sites (logical NOT gates) and the chirality‐selective output of domain walls from 2‐in‐1‐out nanowire junctions (common operation to AND/NAND/OR/NOR gates). The measurements demonstrate both operations can be performed to a good degree of fidelity even in the presence of complex magnetization dynamics that would normally be expected to destroy chirality‐encoded information. Together, these results represent a strong indication of the feasibility of devices where chiral magnetization textures are used to directly carry, rather than merely delineate, data

    Uncoventional Views on Certain Aspects of Toxin-Induced Metabolic Acidosis

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    This discussion will highlight the following 9 specific points that related to metabolic acidosis caused by various toxins. The current recommendation suggests that alcohol dehydrogenase inhibitor fomepizole is preferred to ethanol in treatment of methanol and ethylene glycol poisoning, but analysis of the enzyme kinetics indicates that ethanol is a better alternative. In the presence of a modest increase in serum osmolal gap (<30 mOsm/L), the starting dose of ethanol should be far less than the usual recommended dose. One can take advantage of the high vapor pressure of methanol in the treatment of methanol poisoning when hemodialysis is not readily available. Profuse sweating with increased water ingestion can be highly effective in reducing methanol levels. Impaired production of ammonia by the proximal tubule of the kidney plays a major role in the development of metabolic acidosis in pyroglutamic acidosis. Glycine, not oxalate, is the main final end product of ethylene glycol metabolism. Metabolism of ethylene glycol to oxalate, albeit important clinically, represents less than 1% of ethylene glycol disposal. Urine osmolal gap would be useful in the diagnosis of ethylene glycol poisoning, but not in methanol poisoning. Hemodialysis is important in the treatment of methanol poisoning and ethylene glycol poisoning with renal impairment, with or without fomepizole or ethanol treatment. Severe leucocytosis is a highly sensitive indicator of ethylene glycol poisoning. Uncoupling of oxidative phosphorylation by salicylate can explain most of the manifestations of salicylate poisoning

    Quantifying the computational capability of a nanomagnetic reservoir computing platform with emergent magnetization dynamics

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    Devices based on arrays of interconnected magnetic nano-rings with emergent magnetization dynamics have recently been proposed for use in reservoir computing applications, but for them to be computationally useful it must be possible to optimise their dynamical responses. Here, we use a phenomenological model to demonstrate that such reservoirs can be optimised for classification tasks by tuning hyperparameters that control the scaling and input rate of data into the system using rotating magnetic fields. We use task-independent metrics to assess the rings' computational capabilities at each set of these hyperparameters and show how these metrics correlate directly to performance in spoken and written digit recognition tasks. We then show that these metrics, and performance in tasks, can be further improved by expanding the reservoir's output to include multiple, concurrent measures of the ring arrays magnetic states

    Methanol, formaldehyde, and sodium formate exposure in rat and mouse conceptuses: A potential role of the visceral yolk sac in embryotoxicity

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    BACKGROUND Methanol (CH 3 OH) is believed to be teratogenic based on rodent studies. The mouse is more sensitive than the rat, but mechanisms of toxicity and identification of teratogenic metabolites are uncertain. METHODS Rat and mouse whole embryo cultures are used to distinguish toxicity of CH 3 OH and its metabolites, formaldehyde (HCHO) and formate (HCOONa), which are produced following transit through the visceral yolk sac (VYS), via addition to culture medium, or by direct embryonic exposure through microinjection into the amnion. RESULTS Embryonic viability, increased dysmorphogenesis, and decreased growth parameters were altered in a dose-dependent fashion for each compound. Mouse embryos were more sensitive than rat, as indicated by significant decreases in viability at comparable, lower concentrations. HCHO produced dysmorphogenesis and caused embryolethality at nearly 1000-fold lower concentrations (0.004 mg/ml) than seen with either CH 3 OH or HCOONa. All agents produced incomplete axial rotation and delayed neural tube closure in mice, but only CH 3 OH elicited similar effects in the rat. Increased growth retardation, blood pooling in the head and VYS, enlarged pericardium, accumulation of necrotic matter in the amnion, and hypoplastic prosencephalon were observed in both species with all compounds. Microinjection of compounds into the amnion produced higher mortality in mouse and rat, compared to equimolar amounts added to the culture medium. CH 3 OH did not prevent neural tube closure in the rat when microinjected. CONCLUSIONS HCHO is the most embryotoxic CH 3 OH metabolite and elicits the entire spectrum of lesions produced by CH 3 OH. The VYS serves a general protective role against toxicity and inherent differences in the embryonic metabolism of CH 3 OH may determine species sensitivity. Birth Defects Research (Part A), 2004. © 2004 Wiley-Liss, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/35296/1/20094_ftp.pd

    Dynamically‐driven emergence in a nanomagnetic system

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    Emergent behaviors occur when simple interactions between a system's constituent elements produce properties that the individual elements do not exhibit in isolation. This article reports tunable emergent behaviors observed in domain wall (DW) populations of arrays of interconnected magnetic ring‐shaped nanowires under an applied rotating magnetic field. DWs interact stochastically at ring junctions to create mechanisms of DW population loss and gain. These combine to give a dynamic, field‐dependent equilibrium DW population that is a robust and emergent property of the array, despite highly varied local magnetic configurations. The magnetic ring arrays’ properties (e.g., non‐linear behavior, “fading memory” to changes in field, fabrication repeatability, and scalability) suggest they are an interesting candidate system for realizing reservoir computing (RC), a form of neuromorphic computing, in hardware. By way of example, simulations of ring arrays performing RC approaches 100% success in classifying spoken digits for single speakers
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