scholarly journals Short-Term Dynamics of Bdellovibrio and Like Organisms in Lake Geneva in Response to a Simulated Climatic Extreme Event

2021 ◽  
Author(s):  
J. A. Ezzedine ◽  
A. Janicot ◽  
S. Rasconi ◽  
I. Domaizon ◽  
S. Jacquet
Keyword(s):  
Extreme Event ◽  
Lake Geneva ◽  
Short Term

Methods for Calculation of Annual and Extreme Overflow Events from Combined Sewer Systems

1984 ◽  
Vol 16 (8-9) ◽  
pp. 311-325 ◽  
Author(s):  
N B Johansen ◽  
P Harremoës ◽  
M Jensen
Keyword(s):  
Extreme Event ◽  
Short Term ◽  
Sewer Systems ◽  
Extreme Load ◽  
Combined Sewer ◽  
Receiving Waters ◽  
Water Problems ◽  
Source Of Pollution ◽  
Receiving Water

Overflow from combined systems constitute an increasing source of pollution of receiving waters, as compared to daily wastewater discharges which undergo treatment to a still higher extent. The receiving water problems from overflows are significant both in a long term scale (mean annual load) and in a short term scale (extreme event load). A method for computation of both annual and extreme load is presented. It is based on historical rain series and the use of a time-area model and simple pollutant mixing model in runoff calculation. Statistical calculations for both mean annual load and extreme events have been applied to the computed overflow series. Based on the computerized method simple manual calculations methods have been developed, resulting in graphs and tables for annual load and extreme load.

scholarly journals Increase in ocean acidity variability and extremes under increasing atmospheric CO<sub>2</sub>

2020 ◽  
Vol 17 (18) ◽  
pp. 4633-4662 ◽  
Author(s):  
Friedrich A. Burger ◽  
Jasmin G. John ◽  
Thomas L. Frölicher
Keyword(s):  
Extreme Events ◽  
Co2 Emission ◽  
Emission Scenario ◽  
Extreme Event ◽  
High Surface ◽  
Emission Scenarios ◽  
Short Term ◽  
High Co2 ◽  
Shifting Baseline ◽  
Surface Ocean

Abstract. Ocean acidity extreme events are short-term periods of relatively high [H+] concentrations. The uptake of anthropogenic CO2 emissions by the ocean is expected to lead to more frequent and intense ocean acidity extreme events, not only due to changes in the long-term mean but also due to changes in short-term variability. Here, we use daily mean output from a five-member ensemble simulation of a comprehensive Earth system model under low- and high-CO2-emission scenarios to quantify historical and future changes in ocean acidity extreme events. When defining extremes relative to a fixed preindustrial baseline, the projected increase in mean [H+] causes the entire surface ocean to reach a near-permanent acidity extreme state by 2030 under both the low- and high-CO2-emission scenarios. When defining extremes relative to a shifting baseline (i.e., neglecting the changes in mean [H+]), ocean acidity extremes are also projected to increase because of the simulated increase in [H+] variability; e.g., the number of days with extremely high surface [H+] conditions is projected to increase by a factor of 14 by the end of the 21st century under the high-CO2-emission scenario relative to preindustrial levels. Furthermore, the duration of individual extreme events is projected to triple, and the maximal intensity and the volume extent in the upper 200 m are projected to quintuple. Similar changes are projected in the thermocline. Under the low-emission scenario, the increases in ocean acidity extreme-event characteristics are substantially reduced. At the surface, the increases in [H+] variability are mainly driven by increases in [H+] seasonality, whereas changes in thermocline [H+] variability are more influenced by interannual variability. Increases in [H+] variability arise predominantly from increases in the sensitivity of [H+] to variations in its drivers (i.e., carbon, alkalinity, and temperature) due to the increase in oceanic anthropogenic carbon. The projected increase in [H+] variability and extremes may enhance the risk of detrimental impacts on marine organisms, especially for those that are adapted to a more stable environment.

scholarly journals Do successive climate extremes weaken the resistance of plant communities? An experimental study using plant assemblages

2014 ◽  
Vol 11 (1) ◽  
pp. 109-121 ◽  
Author(s):  
F. E. Dreesen ◽  
H. J. De Boeck ◽  
I. A. Janssens ◽  
I. Nijs
Keyword(s):  
Plant Communities ◽  
Extreme Event ◽  
Recovery Period ◽  
Climate Extremes ◽  
Herbaceous Plant ◽  
Short Term ◽  
Positive Effects ◽  
Negative Effect ◽  
Plant Assemblages ◽  
Heat Extremes

Abstract. The probability that plant communities undergo successive climate extremes increases under climate change. Exposure to an extreme event might elicit acclimatory responses and thereby greater resistance to a subsequent event, but might also reduce resistance if the recovery period is too short or resilience too low. Using experimental herbaceous plant assemblages, we compared the effects of two successive extremes occurring in one growing season (either two drought extremes, two heat extremes or two drought + heat extremes) to those of assemblages being exposed only to the second extreme. Additionally, the recovery period between the successive extremes was varied (2, 3.5 or 6 weeks). Among the different types of climate extremes, combined heat + drought extremes induced substantial leaf mortality and plant senescence, while the effects of drought and heat extremes were smaller. Preceding drought + heat extremes lowered the resistance in terms of leaf survival to a subsequent drought + heat extreme if the recovery period was two weeks, even though the leaves had completely recovered during that interval. No reduced resistance to subsequent extremes was recorded with longer recovery times or with drought or heat extremes. Despite the substantial mortality on the short term, the drought + heat and the heat extremes increased the end-of-season aboveground biomass independent of the number of extreme events or the duration of the recovery period. These results show that recurrent climate extremes with short time intervals can weaken the resistance of herbaceous plant assemblages. This negative effect in the short term can, however, be compensated in the longer term through rapid recovery and secondary positive effects.

scholarly journals EFFECTS OF MEASUREMENT ERROR ON LONG-TERM WAVE STATISTICS

1984 ◽  
Vol 1 (19) ◽  
pp. 24
Author(s):  
Bernard Le Mahaute ◽  
Shen Wang
Keyword(s):  
Measurement Errors ◽  
Extreme Event ◽  
Definite Descriptions ◽  
Extreme Wave ◽  
Short Term ◽  
Wave Statistics ◽  
Record Length ◽  
Long Run

The effect of sample size on confidence band in predicting the extreme wave height is related to the return period and the duration of the sample record length. An estimate of errors resulting from various methods of data acquisition is given. The uncertainties corresponding to various number of years of observation and various measurement errors are analyzed for various return intervals. It is shown that data accuracy and record length are equally important in long term wave predictions. At the present time, the determination of extreme event benefits more from relatively less accurate long-term hindcast calculation rather than short-term high quality measurements. In the long run, a long-term accurate measurement program is imperative if more definite descriptions of extreme events are sought.

High-resolution spatiotemporal heterogeneities of water optical properties in a large lake to infer physical and biogeochemical drivers of primary production

2020 ◽  
Author(s):  
Camille Minaudo ◽  
Daniel Odermatt ◽  
Bieito Fernandez-Castro ◽  
Hannah E. Chmiel ◽  
Sébastien Lavanchy ◽  
...  
Keyword(s):  
Optical Properties ◽  
Primary Production ◽  
Transition Period ◽  
Alternative Methods ◽  
Lake Geneva ◽  
Short Term ◽  
Large Lakes ◽  
Vertical Heterogeneity ◽  
Basin Scale ◽  
Over The Top

&lt;p&gt;Measuring primary production (PP) is of major importance to evaluate how lakes are recovering from eutrophication, and better constrain their role in global biogeochemical cycles. The classical sampling method involving radiolabelled carbon incubated in bottles at selected depths is associated with heavy logistics and prevents scientists from sampling the short-term dynamics of PP. Therefore, we investigate alternative methods based on oxygen sensors and optical properties.&lt;/p&gt;&lt;p&gt;To explore the interplay between biogeochemical and physical processes and how they are related to PP in large lakes, we have deployed since October 2018 a sophisticated autonomous profiler in Lake Geneva, Switzerland. The so-called Thetis profiler measures with a centimeter resolution backscattering and fluorescence at discrete wavelengths, hyperspectral absorption and attenuation, hyperspectral reflectance, along with temperature, dissolved oxygen and conductivity. The profiler was deployed over contrasted seasons and recorded these parameters every three hours over the top 50 m of the water column.&lt;/p&gt;&lt;p&gt;Observations revealed large spatiotemporal heterogeneities of optical properties as a result of seasonal and short-term (weekly to sub-daily) physical and biogeochemical processes. Diel cycles in the optical properties representing phytoplankton abundance resulted from night-time convection and grazing and production during the day. Short-lived but strong upwelling events triggered sudden disruptive shifts in the phytoplankton community composition over the fall to winter transition period which, in turn, impacted the oxygen budgets, opening the door to a better understanding of the vertical heterogeneity of PP directly from inherent optical properties. The data also features advected riverine and resuspended sediments during storms and snowmelt, and during upwelling events, respectively.&lt;/p&gt;&lt;p&gt;This in-situ data is now being combined with remotely sensed water quality parameters (OLCI products from Sentinel 3A and 3B) and a three-dimensional hydrodynamic model of Lake Geneva (www.meteolakes.ch) to upscale PP estimates from local to basin scale.&lt;/p&gt;

Conceptual short-term memory (CSTM) supports core claims of Christiansen and Chater

2016 ◽  
Vol 39 ◽  
Author(s):  
Mary C. Potter
Keyword(s):  
Working Memory ◽  
Rapid Serial Visual Presentation ◽  
Language Comprehension ◽  
Short Term Memory ◽  
Visual Presentation ◽  
Long Term Memory ◽  
Short Term ◽  
Term Memory ◽  
Use Of Knowledge

AbstractRapid serial visual presentation (RSVP) of words or pictured scenes provides evidence for a large-capacity conceptual short-term memory (CSTM) that momentarily provides rich associated material from long-term memory, permitting rapid chunking (Potter 1993; 2009; 2012). In perception of scenes as well as language comprehension, we make use of knowledge that briefly exceeds the supposed limits of working memory.

Ultrastructural Changes of Canine Kidneys During 24-Hour Perfusion on a LI-400 Preservation System

1971 ◽  
Vol 29 ◽  
pp. 316-317
Author(s):  
M. O. Magnusson ◽  
D. G. Osborne ◽  
T. Shimoji ◽  
W. S. Kiser ◽  
W. A. Hawk
Keyword(s):  
Electron Microscopy ◽  
Electrolyte Solution ◽  
Ultrastructural Changes ◽  
Midline Incision ◽  
Short Term ◽  
Pentobarbital Anesthesia ◽  
Pulsatile Perfusion

Short term experimental and clinical preservation of kidneys is presently best accomplished by hypothermic continuous pulsatile perfusion with cryoprecipitated and millipore filtered plasma. This study was undertaken to observe ultrastructural changes occurring during 24-hour preservation using the above mentioned method.A kidney was removed through a midline incision from healthy mongrel dogs under pentobarbital anesthesia. The kidneys were flushed immediately after removal with chilled electrolyte solution and placed on a LI-400 preservation system and perfused at 8-10°C. Serial kidney biopsies were obtained at 0-½-1-2-4-8-16 and 24 hours of preservation. All biopsies were prepared for electron microscopy. At the end of the preservation period the kidneys were autografted.

Polychlorinated biphenyl induced hepatocyte alterations

1987 ◽  
Vol 45 ◽  
pp. 716-717
Author(s):  
D.N. Collins ◽  
J.N. Turner ◽  
K.O. Brosch ◽  
R.F. Seegal
Keyword(s):  
Lipid Droplets ◽  
Wistar Rats ◽  
Homovanillic Acid ◽  
Polychlorinated Biphenyl ◽  
Corn Oil ◽  
Environmental Pollutants ◽  
Short Term ◽  
Pcb Congeners ◽  
Urinary Levels ◽  
The Brain

Polychlorinated biphenyls (PCBs) are a ubiquitous class of environmental pollutants with toxic and hepatocellular effects, including accumulation of fat, proliferated smooth endoplasmic recticulum (SER), and concentric membrane arrays (CMAs) (1-3). The CMAs appear to be a membrane storage and degeneration organelle composed of a large number of concentric membrane layers usually surrounding one or more lipid droplets often with internalized membrane fragments (3). The present study documents liver alteration after a short term single dose exposure to PCBs with high chlorine content, and correlates them with reported animal weights and central nervous system (CNS) measures. In the brain PCB congeners were concentrated in particular regions (4) while catecholamine concentrations were decreased (4-6). Urinary levels of homovanillic acid a dopamine metabolite were evaluated (7).Wistar rats were gavaged with corn oil (6 controls), or with a 1:1 mixture of Aroclor 1254 and 1260 in corn oil at 500 or 1000 mg total PCB/kg (6 at each level).

Acetaminophen: Macula densa hypersecretory activity by induced hepatotoxicity

1987 ◽  
Vol 45 ◽  
pp. 934-935
Author(s):  
S.S. Poolsawat ◽  
C.A. Huerta ◽  
S.TY. Lae ◽  
G.A. Miranda
Keyword(s):  
Cell Proliferation ◽  
Liver Function ◽  
Chronic Inflammation ◽  
Foam Cell ◽  
Term Effect ◽  
Short Term ◽  
Drug Induced ◽  
Experimental Induction ◽  
Tissue Alterations ◽  
Toxic Responses

Introduction. Experimental induction of altered histology by chemical toxins is of particular importance if its outcome resembles histopathological phenomena. Hepatotoxic drugs and chemicals are agents that can be converted by the liver into various metabolites which consequently evoke toxic responses. Very often, these drugs are intentionally administered to resolve an illness unrelated to liver function. Because of hepatic detoxification, the resulting metabolites are suggested to be integrated into the macromolecular processes of liver function and cause an array of cellular and tissue alterations, such as increased cytoplasmic lysis, centrilobular and localized necroses, chronic inflammation and “foam cell” proliferation of the hepatic sinusoids (1-4).Most experimentally drug-induced toxicity studies have concentrated primarily on the hepatic response, frequently overlooking other physiological phenomena which are directly related to liver function. Categorically, many studies have been short-term effect investigations which seldom have followed up the complications to other tissues and organs when the liver has failed to function normally.

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