scholarly journals Water mite predation on zooplankton of a tropical lake

2002 ◽  
Vol 62 (4a) ◽  
pp. 565-571 ◽  
Author(s):  
C. R. CASSANO ◽  
M. S. M CASTILHO-NOLL ◽  
M. S. ARCIFA
Keyword(s):  
Laboratory Experiments ◽  
Average Rate ◽  
Dorsal Side ◽  
Tropical Lake ◽  
Water Mite ◽  
Predatory Activity ◽  
Paulo State ◽  
Direct Observations ◽  
Mite Predation ◽  
Ceriodaphnia Cornuta

Water mite (Krendowskia sp.) predation on zooplanktonic species from Lake Monte Alegre (São Paulo State, Brazil) was tested in laboratory experiments. One cladoceran, Daphnia gessneri, two copepods, Tropocyclops prasinus and Thermocyclops decipiens, and Chaoborus larvae III and IV were supplied as prey to adult mites. The cladoceran Ceriodaphnia cornuta was used in the experiment with mite nymphs. Only D.gessneri was preyed on by mites, at an average rate of 7 ind./mite/day, at 23-24ºC. Although Chaoborus was not eaten by the predator in the experiment, in direct observations older larvae were seen to be seized by several mites, both predators and prey sinking to the bottom of the vessel. Adult Daphnia was grabbed by its dorsal side, swimming together with the mite. There was an increase in predatory activity two hours after sunset.

scholarly journals Estimation of permafrost thawing rates in a sub-arctic catchment using recession flow analysis

2009 ◽  
Vol 13 (5) ◽  
pp. 595-604 ◽  
Author(s):  
S. W. Lyon ◽  
G. Destouni ◽  
R. Giesler ◽  
C. Humborg ◽  
M. Mörth ◽  
...  
Keyword(s):  
Average Rate ◽  
Flow Analysis ◽  
The Arctic ◽  
Northern Sweden ◽  
The Past ◽  
Direct Observations ◽  
Flow Pathways ◽  
Thawing Rate ◽  
Permafrost Thawing

Abstract. Permafrost thawing is likely to change the flow pathways taken by water as it moves through arctic and sub-arctic landscapes. The location and distribution of these pathways directly influence the carbon and other biogeochemical cycling in northern latitude catchments. While permafrost thawing due to climate change has been observed in the arctic and sub-arctic, direct observations of permafrost depth are difficult to perform at scales larger than a local scale. Using recession flow analysis, it may be possible to detect and estimate the rate of permafrost thawing based on a long-term streamflow record. We demonstrate the application of this approach to the sub-arctic Abiskojokken catchment in northern Sweden. Based on recession flow analysis, we estimate that permafrost in this catchment may be thawing at an average rate of about 0.9 cm/yr during the past 90 years. This estimated thawing rate is consistent with direct observations of permafrost thawing rates, ranging from 0.7 to 1.3 cm/yr over the past 30 years in the region.

Parasite-mediated reductions in the survival and reproduction of the backswimmer Buenoa scimitra (Hemiptera: Notonectidae)

Parasitology ◽  
1982 ◽  
Vol 85 (3) ◽  
pp. 593-603 ◽  
Author(s):  
Carmine A. Lanciani
Keyword(s):  
Linear Function ◽  
Death Rate ◽  
Birth Rate ◽  
Laboratory Experiments ◽  
Survival Rates ◽  
Linear Functions ◽  
Water Mite ◽  
Death Rates ◽  
First Instar ◽  
Survival And Reproduction

The effect of the parasitic water mite Hydrachna virella on its host Buenoa scimitra was investigated using laboratory experiments. The mite parasitizes all but the first instar of the host. Survival rates were found to be greater among unparasitized than parasitized individuals of these instars. Instantaneous death rates were observed to be linear functions of the number of mites supported/host. The mite's effect on the host's death rate appeared to be directly related to the size of the engorged mite compared to the size of the host; greater relative sizes were associated with greater impacts. Unparasitized females oviposited significantly more eggs than parasitized females, and the instantaneous birth rate of the host was observed to be a non-linear function of mite load.

scholarly journals Spatial distribution for diarrhea hospitalization in São Paulo State

2017 ◽  
Vol 17 (3) ◽  
pp. 475-482
Author(s):  
Fernanda Pires Cecchetti Vaz ◽  
Luiz Fernando Costa Nascimento
Keyword(s):  
Low Income ◽  
Hospital Admissions ◽  
Average Rate ◽  
Sao Paulo ◽  
São Paulo ◽  
Thematic Map ◽  
Admission Rates ◽  
Paulo State ◽  
Hospitalization Rates ◽  
São Paulo State

Abstract Objectives: to identify spatial pattern on hospitalization rates of children with diarrhea in the counties in São Paulo State. Methods: ecological and exploratory study on hospitalized data of children with diarrhea under the age of four in 2008 and 2012, the IDH mothers with low schooling level and children living with a low income less than half minimum wage were obtained from Datasus and inserted into digital map of the counties in São Paulo State. Moran's global index (I) and Pearson's coefficients correlation and thematic maps of hospitalization rates of 1,000 children, Moran maps and kernel map were calculated. Results: there were 34, 802 hospital admissions, with an average rate of 4.7 hospitalizations / 1,000 children (SD=7.2). Hospitalization rates were correlated only with schooling (r= 0.09, p<0.05). Moran's index for hospitalization rate was I=0.31(p<0.01). The thematic map of the hospital admission rates showed a cluster of counties in the west of the State; the kernel map showed a higher density of hospitalization in this region and the Moran map identified 57 counties which deserve attention. Conclusions: the results provide subsidies for the counties and regional managers to implement measurements aiming to reduce these rates.

Water Mite Predation on Planktonic Cladocera: Parallel Curve Analysis of Functional Responses

Oikos ◽  
1993 ◽  
Vol 66 (1) ◽  
pp. 5 ◽  
Author(s):  
Margaret I. Butler ◽  
Carolyn W. Burns
Keyword(s):  
Curve Analysis ◽  
Functional Responses ◽  
Water Mite ◽  
Mite Predation

Nonlinear Dynamical Mechanisms Connecting Ocean Giant Waves and Wave Groups

2002 ◽  
Author(s):  
Ming-Yang Su ◽  
Cheng-Han Tsai ◽  
Yin-Chern Lin ◽  
Hsiang-Mao Tseng
Keyword(s):  
Laboratory Experiments ◽  
Ocean Waves ◽  
Wave Group ◽  
Coastal Zones ◽  
Wave Groups ◽  
Nonlinear Dynamical ◽  
The Past ◽  
Direct Observations ◽  
Close Relationship ◽  
Statistical Relationships

It is well known by direct observations that large ocean waves occur, more frequently among a wave group or group waves, than individually. Several statistical relationships among these two wave features have also been discussed in the past thirty years. However, the dynamical reasons (or mechanisms), why these two ocean wave features are often related, have seldom been discussed in sufficient details. The purpose of this paper are two fold: (1) to review various observations of wave groups and giant waves obtained from deep seas, coastal zones and laboratory experiments, and (2) to provide several significant physical and dynamical mechanisms for explaining the observed close relationship between these two important wave features. (3) to provide an example of a giant wave (called mad-dog waves) event, which resulted in the drowning of fishermen, occurred on the coast of Taiwan.

scholarly journals Influence of seston quantity and quality on growth of tropical cladocerans

2005 ◽  
Vol 65 (1) ◽  
pp. 77-89 ◽  
Author(s):  
A. S Ferão-Filho ◽  
M. S. Arcifa ◽  
C. Fileto
Keyword(s):  
Growth Rate ◽  
Clutch Size ◽  
Room Temperature ◽  
Tropical Lake ◽  
Seasonal Differences ◽  
Food Quantity ◽  
Ankistrodesmus Falcatus ◽  
Laboratory Cultures ◽  
Energy Limitation ◽  
Ceriodaphnia Cornuta

The seston of the small, shallow, and tropical lake Monte Alegre was tested for quantity and quality for cladocerans by growth bioassays, which were carried out in spring (Daphnia gessneri and Moina micrura), summer (D. gessneri, M. micrura, Ceriodaphnia cornuta, and Simocephalus mixtus), and winter (D. gessneri and D. ambigua). Cohorts of newborns originating from ovigerous females collected in the lake or from laboratory cultures were submitted, at a room temperature of 23ºC to the following treatments: (1) the chlorophytes Ankistrodesmus falcatus and/or Scenedesmus spinosus; (2) lake seston; and (3) lake seston + chlorophytes. Growth rate, clutch size, and fecundity were evaluated. Seston alone was not the best food for promoting cladoceran growth. There were seasonal differences in food quantity and quality with spring and summer seston being better for growth than that of the winter. Adding chlorophytes to the seston increased clutch size and fecundity for most species in summer and winter, but not in spring. Energy limitation seems to be the most important factor influencing cladoceran growth in summer and especially in winter.

scholarly journals Estimation of permafrost thawing rates in a sub-arctic catchment using recession flow analysis

2009 ◽  
Vol 6 (1) ◽  
pp. 63-83 ◽  
Author(s):  
S. W. Lyon ◽  
G. Destouni ◽  
R. Giesler ◽  
C. Humborg ◽  
M. Mörth ◽  
...  
Keyword(s):  
Average Rate ◽  
Flow Analysis ◽  
Local Scale ◽  
Northern Sweden ◽  
The Past ◽  
Direct Observations ◽  
Flow Pathways ◽  
Thawing Rate ◽  
Permafrost Thawing

Abstract. Permafrost thawing is likely to change the flow pathways taken by water as it moves through arctic and sub-arctic landscapes. The location and distribution of these pathways directly influence the carbon and other biogeochemical cycling in northern latitude catchments. Direct observations of permafrost depth are difficult to perform at scales larger than a local scale. Using recession flow analysis, it may be possible to detect and estimate the rate of permafrost thawing based on a long-term streamflow record. We demonstrate the application of this approach to the sub-arctic Abiskojokken catchment in northern Sweden. Based on recession flow analysis, we estimate that permafrost in this catchment may be thawing at an average rate of about 0.9 cm/yr during the past 90 years. This estimated thawing rate is consistent with direct observations of permafrost thawing rates, ranging from 0.7 to 1.3 cm/yr over the past 30 years in the region.

Covering of cometary nucleus by refractory crust and its evolution into asteroid-like body

1999 ◽  
Vol 173 ◽  
pp. 365-370
Author(s):  
Kh.I. Ibadinov
Keyword(s):  
Laboratory Experiments ◽  
Cometary Nucleus ◽  
Sublimation Rate ◽  
Cometary Nuclei ◽  
Short Period Comet ◽  
Short Period ◽  
Brightness Decrease ◽  
Crust Thickness ◽  
Ice Sublimation ◽  
Period Comet

AbstractFrom the established dependence of the brightness decrease of a short-period comet dependence on the perihelion distance of its orbit it follows that part of the surface of these cometary nuclei gradually covers by a refractory crust. The results of cometary nucleus simulation show that at constant insolation energy the crust thickness is proportional to the square root of the insolation time and the ice sublimation rate is inversely proportional to the crust thickness. From laboratory experiments resulted the thermal regime, the gas productivity of the nucleus, covering of the nucleus by the crust, and the tempo of evolution of a short-period comet into the asteroid-like body studied.

Direct observations of radiation-enhanced transformations in glass

1983 ◽  
Vol 41 ◽  
pp. 354-355
Author(s):  
J. F. DeNatale ◽  
D. G. Howitt
Keyword(s):  
Glass Matrix ◽  
Diffusion Mechanism ◽  
Bubble Formation ◽  
Silicate Glasses ◽  
Phase Decomposition ◽  
Direct Observations ◽  
Thin Foils ◽  
Oxygen Bubble ◽  
Electron Energy Loss ◽  
Kinetics Of

The electron irradiation of silicate glasses containing metal cations produces various types of phase separation and decomposition which includes oxygen bubble formation at intermediate temperatures figure I. The kinetics of bubble formation are too rapid to be accounted for by oxygen diffusion but the behavior is consistent with a cation diffusion mechanism if the amount of oxygen in the bubble is not significantly different from that in the same volume of silicate glass. The formation of oxygen bubbles is often accompanied by precipitation of crystalline phases and/or amorphous phase decomposition in the regions between the bubbles and the detection of differences in oxygen concentration between the bubble and matrix by electron energy loss spectroscopy cannot be discerned (figure 2) even when the bubble occupies the majority of the foil depth.The oxygen bubbles are stable, even in the thin foils, months after irradiation and if van der Waals behavior of the interior gas is assumed an oxygen pressure of about 4000 atmospheres must be sustained for a 100 bubble if the surface tension with the glass matrix is to balance against it at intermediate temperatures.

Metallurgical Effects of Grain Boundary Ledges

1977 ◽  
Vol 35 ◽  
pp. 126-129
Author(s):  
L.E. Murr
Keyword(s):  
Grain Boundary ◽  
Quantitative Data ◽  
Mechanical Treatment ◽  
Unit Length ◽  
Physical And Mechanical Properties ◽  
Direct Observations ◽  
Transmission Electron ◽  
Properties Of Materials ◽  
Thermo Mechanical Treatment ◽  
Ledge Density

Ledges in grain boundaries can be identified by their characteristic contrast features (straight, black-white lines) distinct from those of lattice dislocations, for example1,2 [see Fig. 1(a) and (b)]. Simple contrast rules as pointed out by Murr and Venkatesh2, can be established so that ledges may be recognized with come confidence, and the number of ledges per unit length of grain boundary (referred to as the ledge density, m) measured by direct observations in the transmission electron microscope. Such measurements can then give rise to quantitative data which can be used to provide evidence for the influence of ledges on the physical and mechanical properties of materials.It has been shown that ledge density can be systematically altered in some metals by thermo-mechanical treatment3,4.

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