Factors affecting the relative distribution of Atriplex vesicaria and Kochia sedifolia (Chenopodiaceae) in the arid zone of South Australia

1965 ◽  
Vol 13 (3) ◽  
pp. 419 ◽  
Author(s):  
BB Carrodus ◽  
RL Specht
Keyword(s):  
Experimental Approach ◽  
Surface Soil ◽  
Arid Zone ◽  
South Australia ◽  
The Other ◽  
Relative Distribution ◽  
Factors Affecting ◽  
Heavy Clay ◽  
Detailed Work ◽  
Normal Rainfall

The factors controlling the relative distribution of Atriplex vesicaria and Kochia sedifolia were obscure, and explanations in the literature unsatisfactory. This paper describes the results of an experimental approach to an understanding of these factors. A survey of the soils on which A. vesicaria and K. sedifolia are found in the arid zone of South Australia revealed that the distribution of the two species is usually correlated with the depth to which the soil is wetted by the normal rainfall. K. sedifolia, a deep-rooted species, is frequently found on soils which can be wetted to a depth of 2 ft or more. A. vesicaria, a shallow-rooted species, is found on soils in which a heavy clay subsoil or hardpan impedes penetration of water beyond 12 in. From experimental evidence it appears that: (1) either species can grow successfully in pots of the surface soil associated with the other species; (2) each community utilizes water at the same rate; (3) there is no difference between the two species in the rate of defoliation in response to drought conditions, when held at night either in a dry atmosphere or in one with a relative humidity exceeding 85 %; (4) A. vesicaria can reduce the percentage moisture in the soil to a significantly lower level than can K. sedifolia when subjected to drought. These observations are discussed in relation to field conditions, and hypotheses are proposed to explain why these two species are usually found in distinct communities. More detailed work is necessary to test these hypotheses. I.

Factors affecting pitfall capture rates of small ground vertebrates in arid South Australia. I. The influence of weather and moon phase on capture rates of reptiles

2001 ◽  
Vol 28 (1) ◽  
pp. 53 ◽  
Author(s):  
J. L. Read ◽  
K. E. Moseby
Keyword(s):  
Cloud Cover ◽  
Arid Zone ◽  
South Australia ◽  
Major Change ◽  
Effect Of Temperature ◽  
Representative Sampling ◽  
Factors Affecting ◽  
Wide Range ◽  
Maximum Temperatures ◽  
Capture Rates

The effect of temperature, humidity, cloud cover, wind and rainfall on capture rates of small reptiles in pitfall traps was assessed in the South Australian arid zone. Capture rates increased significantly with increased ambient temperature. Captures of diurnal reptiles were highest when the minimum temperature was greater than 26°C, while captures of nocturnal reptiles peaked when maximum temperatures exceeded 34°C. Dark nights, particularly those with cloud cover, yielded higher captures of nocturnal reptiles than moonlit or cloudless nights. Representative sampling periods to record a wide range of reptile species should extend for at least 8 days, which is the modal period of a major change in daily temperature during the summer months.

Comparative Leaf Water Potentiais of Plants in Burnt and Unburnt Dry Sclerophyll Vegetation

1993 ◽  
Vol 41 (6) ◽  
pp. 661 ◽  
Author(s):  
JM Guo ◽  
R Sinclair
Keyword(s):  
Surface Soil ◽  
South Australia ◽  
Root Systems ◽  
The Other ◽  
Burnt Area ◽  
Burnt Site ◽  
Water Potentials ◽  
And Control ◽  
Intact Root ◽  
Sampling Times

Leaf (xylem) water potentials were measured in summer and autumn on four species, Eucalyptus fasciculosa, Pultenaea daphnoides, Platylobium obtusangulum and Acacia myrtifolia growing in the understorey of sclerophyll stringybark vegetation in the Mt Lofty Ranges, South Australia. Plants regenerating in an area burnt by bushfire 2 years previously were compared with plants in an adjacent unburnt area. The Acacia was killed by fire and subsequently regenerated from seed. The other three species survived and resprouted from basal or epicormic buds. It was expected that shrubs regenerating from basal buds would be better hydrated in summer, as a large intact root system would supply a reduced canopy, and that seedlings, with smaller root systems than unburnt adults, would be more stressed. The Acacia was indeed significantly more stressed during summer in the burnt area. However the Platylobium was also more stressed than the controls, while the Pultenaea showed no significant differences between burnt and control areas. The Eucalyptus showed no differences between sites, nor between any of the three sampling times. The more negative water potentials of some of the regenerating plants are explained by greater exposure of surface soil on the burnt site, leading to more rapid drying of the surface soil in summer.

Water Potential and Stomatal Conductance of Three Eucalyptus Species in the Mount Lofty Ranges, South Australia: Responses to Summer Drought

1980 ◽  
Vol 28 (6) ◽  
pp. 499 ◽  
Author(s):  
R Sinclair
Keyword(s):  
Stomatal Conductance ◽  
Water Potential ◽  
South Australia ◽  
Late Summer ◽  
Distribution Patterns ◽  
The Other ◽  
Late Winter ◽  
Eucalyptus Species ◽  
Summer Drought ◽  
Factors Affecting

Water potential and stomatal conductance were measured for three eucalypt species: Eucalyptus obliqua L'Hérit., E. fasciculosa F. Muell. and E. leucoxylon F. Muell. Field sites were located in the Mt Lofty Ranges, S.A., near the lower altitudinal limits of the E. obliqua population, where this species begins to be replaced by one or other of the other two. Pairs of trees, one pair of each species, were selected at each site growing within a few metres of each other. Measurements were made in late winter 1977 and during the unusually dry summer of 1977-78. In late winter E. obliqua and E. fasciculosa results were similar. Both had dawn water potential maxima of approximately -0.4 MPa, and stomatal conductance was high throughout the day. By mid summer E. obliqua was suffering water stress. Dawn water potential maxima of -1.93 and -4.35 MPa were measured, and stomatal conductance was low, but not zero, throughout the day. Adjacent E. fasciculosa showed few signs of stress; dawn maximum water potential was -0.7 MPa, and stornatal conductances were high. By late summer both water potentials and stornatal conductances of E. obliqua were much lower than those of adjacent trees of either of the other two species. The significance of these differences is discussed in relation to factors affecting eucalypt distribution patterns.

Relative Distribution and Incidence of Viruses Associated with Disease Outbreaks in Tomato Fields in Trinidad

2006 ◽  
Vol 7 (1) ◽  
pp. 29
Author(s):  
S. N. Rampersad
Keyword(s):  
Production Systems ◽  
Management Strategies ◽  
Disease Outbreaks ◽  
Tobacco Etch Virus ◽  
The Other ◽  
Multiple Infections ◽  
Relative Distribution ◽  
Tomato Production ◽  
Viral Pathogen ◽  
High Incidence

Tomato production in Trinidad has suffered considerable losses in yield and fruit quality due to infections of hitherto surmised etiology. In order to develop strategies for controlling viral diseases in tomato, the relative distribution and incidence of seven viruses that commonly infect tomato were determined. Of the 362 samples tested, Potato yellow mosaic Trinidad virus (PYMTV) was found in every farm except two and was present at relatively high incidence throughout the country. Tobacco mosaic virus (TMV) and Tobacco etch virus (TEV) were found in fewer farms and at lower incidences while the other viruses were absent. Single infections of either virus were more common than double infections and multiple infections were rare but present. The results indicated that PYMTV is the predominant and most important viral pathogen in tomato production systems in Trinidad; however, begomovirus disease management strategies will also have to accommodate controls Accepted for publication 10 January 2006. Published 9 March 2006.

Reynolds-averaged Navier–Stokes simulation of hydrofoil effects on hydrodynamic coefficients of a catamaran in forced oscillation

2016 ◽  
Vol 231 (2) ◽  
pp. 364-383
Author(s):  
Amin Najafi ◽  
Mohammad Saeed Seif
Keyword(s):  
High Speed ◽  
Experimental Approach ◽  
Navier Stokes ◽  
Hydrodynamic Coefficients ◽  
Laboratory Equipment ◽  
Factors Affecting ◽  
High Frequencies ◽  
Frequency Independent ◽  
Reynolds Averaged Navier Stokes

Determination of high-speed crafts’ hydrodynamic coefficients will help to analyze the dynamics of these kinds of vessels and the factors affecting their dynamic stabilities. Also, it can be useful and effective in controlling the vessel instabilities. The main purpose of this study is to determine the coefficients of longitudinal motions of a planing catamaran with and without a hydrofoil using Reynolds-averaged Navier–Stokes method to evaluate the foil effects on them. Determination of hydrodynamic coefficients by experimental approach is costly and requires meticulous laboratory equipment; therefore, utilizing the numerical methods and developing a virtual laboratory seem highly efficient. In this study, the numerical results for hydrodynamic coefficients of a high-speed craft are verified against Troesch’s experimental results. In the following, after determination of hydrodynamic coefficients of a planing catamaran with and without foil, the foil effects on its hydrodynamic coefficients are evaluated. The results indicate that most of the coefficients are frequency-independent especially at high frequencies.

Investigation on Polymer Adsorption and Retention in a Polymer Flooded Reservoir

2013 ◽  
Vol 734-737 ◽  
pp. 1200-1203
Author(s):  
Shu Qiang Liu ◽  
Ji Cheng Zhang ◽  
Jin Cheng Xu
Keyword(s):  
Polymer Solution ◽  
Influencing Factors ◽  
Polymer Adsorption ◽  
Solution Concentration ◽  
Injection Rate ◽  
The Other ◽  
Injection Time ◽  
Factors Affecting ◽  
Dynamic Factors ◽  
Polymer Retention

During polymer flooding, certain amount of polymer would be lost. Polymer retention causes sweep volume expanding on one side, it also causes polymer loss on the other. Therefore, it is a very important topic to study the influencing factors of polymer retention. There are many factors affecting polymer retention process. This paper mainly studied the influence from dynamic factors such as polymer solution concentration, injection rate, injection time, injected pv number. This paper investigated the influence of these factors on polymer retention process, and optimized these factors to minimize polymer loss in reservoir.

Factors affecting changes in the intraocular pressure after phacoemulsification surgery

2020 ◽  
Vol 1 (3) ◽  
pp. 166-172
Author(s):  
Rita Dhamankar ◽  
◽  
Suhas S Haldipurkar ◽  
Tanvi Haldipurkar ◽  
Vijay Shetty ◽  
...  
Keyword(s):  
Intraocular Pressure ◽  
Anterior Chamber ◽  
Axial Length ◽  
Anterior Chamber Depth ◽  
The Other ◽  
Factors Affecting ◽  
Factors Associated ◽  
Post Surgery ◽  
Unit Increase ◽  
The Mean

AIM: To assess the changes in anterior chamber parameters and examine the factors associated with changes in the intraocular pressure (IOP) in individuals who have undergone phacoemulsification surgery. METHODS: It is a longitudinal analysis of secondary clinical data collected from 105 non-glaucomatous eyes (82 patients) undergoing a cataract surgery. We studied the association between anterior chamber parameters, grade of cataract, demographics, and changes in the IOP over a period of three weeks. We also evaluated the association between the pressure-depth (PD) ratio and changes in the IOP during this time. RESULTS: The mean age (SD) of the 82 patients was 60.1±7.8y. The mean±standard deviation (SD) IOP was 15.06±3.36 mm Hg pre-operatively; it increased to 15.75±4.21 mm Hg on day one (P=0.20). In the multifactorial models, the mean IOP was -1.715 (95%CI: -2.795, -0.636) mm Hg on day 21±5 compared with the pre-operative values. The anterior chamber depth (ACD), axial length, age, sex, and grade of cataract were not significantly associated with changes in the IOP. Each unit increase in the PD ratio was associated with an increase in the mean IOP by 1.289 mm Hg (95%CI: 0.906, 1.671). After adjusting for pre-operative PD ratio, none of the other variables (ACD, axial length, temporal angle) were significantly associated with changes in mean IOP. CONCLUSION: The PD ratio was the single most important factor associated with the changes in post-operative IOP over three weeks post-surgery.

scholarly journals Using Hotspots Algebra to analyze crime events and their urban context

2017 ◽  
Vol 18 (1) ◽  
pp. 9-26
Author(s):  
Lenin Heredia G. ◽  
Germán E. Bravo C.
Keyword(s):  
Temporal Analysis ◽  
The Other ◽  
Crime Analysis ◽  
Temporal Context ◽  
Urban Context ◽  
Factors Affecting ◽  
Spatial Factors ◽  
Spatial Influence ◽  
Police Agencies ◽  
The Subject

Hotspots analysis is essential in the criminology field and quite important in decisions making for police agencies because it permits the enhancement of allocation of police resources for timely and adequate actions. There exist different techniques for analysis and generation of hotspots, limited by its difficulty to consider other urban and demographic factors that could be the cause of the emergence of these hotspots or their influence over other factors. On the other hand, it is also difficult and unusual to analyze hotspots in a temporal context. This paper seeks, through spatial-temporal operations based in hotspots, to go beyond of classical crime analysis with hotspots, by looking for the spatial influence of other spatial factors over and analyzing also their relationship in a temporal context. The paper initially presents and analyze the performance of various techniques for hotspot generation and determines that STAC technique from CrimeStat is the more suitable for the proposed objective. Then, it defines a hotspot algebra allowing the combined study of crime and spatial factors affecting it and/or been affected by crime events. Temporal analysis includes the hotspots generation for days of the week and/or months in a year. In this way it is possible to study causality relationships and/or correlations among the studied phenomena and the spatial-temporal environment where crime occurs. Therefore, it is possible to define and apply informed actions, primarily concerning the allocation of police resources. Finally, it shows some application examples, thematic as well as temporal analysis, of hotspot algebra using crime data from Bogota for the years 2011 to 2013; finally, some future works in the subject are proposed.

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