The relation of population densities of the antagonist, Laetisaria arvalis, to seedling diseases of table beet incited by Pythium ultimum

1986 ◽  
Vol 32 (2) ◽  
pp. 156-159 ◽  
Author(s):  
S. Bruce Martin ◽  
G. S. Abawi ◽  
H. C. Hoch
Keyword(s):  
Low Temperature ◽  
Population Density ◽  
Disease Incidence ◽  
Pythium Ultimum ◽  
Quadratic Model ◽  
Damping Off ◽  
Population Densities ◽  
Field Soils ◽  
Laetisaria Arvalis ◽  
The Relationship

Sclerotia of Laetisaria arvalis were added to raw or steamed table beet field soils infested with Pythium ultimum and other low-temperature Pythium spp. to determine the relationship between soil population densities of the antagonist to disease incidence. Decrease in disease incidence of table beet seedlings and final Pythium spp. inoculum densities were linearly related to increasing population density of the antagonist in raw field soils. In P. ultimum infested steamed soils, decreasing disease incidence was also related to increasing population densities of L. arvalis, but the relationship was curvilinear and was described by a quadratic model. The latter models also described the decrease in P. ultimum inoculum densities with increasing levels of the antagonist. Percentages of healthy plants (those surviving the pre- and post-emergence damping-off disease phases) were increased approximately 20% in raw soils containing 100 sclerotia of L. arvalis per gram soil in comparison with those of unamended soils. However, in Pythium infested steamed soils, percentages of healthy plants in soil amended with 100 sclerotia of L. arvalis per gram soil were increased by 40–60%.

Variability in Grouping in the Eastern Grey Kangaroo, Macropus giganteus I. Group Density and Group Size

1984 ◽  
Vol 11 (3) ◽  
pp. 423 ◽  
Author(s):  
CJ Southwell
Keyword(s):  
Seasonal Variation ◽  
Population Density ◽  
Group Size ◽  
Spatial Dispersion ◽  
Population Densities ◽  
Forest Habitat ◽  
Open Forest ◽  
Grey Kangaroo ◽  
Group Density ◽  
The Relationship

The effects of season, population density and habitat on group density and group size in the eastern grey kangaroo were examined. In an open forest habitat, both group density and group size increased significantly with population density, but no seasonal variation was detected for either parameter. The relationship with population density was logarithmic for group density and exponential for group size. In a tall shrubland habitat both group density and group size increased with population density, but the range of population densities sampled was too narrow for the nature of the relationships to be determined. Group density was significantly higher, and group size significantly lower, in the tall shrubland than in the open forest. Possible reasons for this difference in spatial dispersion between habitats are discussed.

scholarly journals Variation in space and time: a long-term examination of density-dependent dispersal in a woodland rodent

2019 ◽  
Author(s):  
Simon T. Denomme-Brown ◽  
Karl Cottenie ◽  
J. Bruce Falls ◽  
E. Ann Falls ◽  
Ronald J. Brooks ◽  
...  
Keyword(s):  
Time Series ◽  
Population Density ◽  
Local Density ◽  
Spatial Scales ◽  
Deer Mice ◽  
Population Densities ◽  
Density Dependent ◽  
Regional Population ◽  
The Relationship ◽  
Density Dependent Dispersal

AbstractDispersal is a fundamental ecological process that can be affected by population density, yet studies report contrasting effects of density on propensity to disperse. Additionally, the relationship between dispersal and density is seldom examined using densities measured at different spatial scales or over extensive time-series. We used 51-years of trapping data to examine how dispersal by wild deer mice (Peromyscus maniculatus) was affected by changes in both local and regional population densities. We examined these patterns over both the entire time-series and also in ten-year shifting windows to determine whether the nature and strength of the relationship changed through time. Probability of dispersal decreased with increased local and regional population density, and the negative effect of local density on dispersal was more pronounced in years with low regional densities. Additionally, the strength of negative density-dependent dispersal changed through time, ranging from very strong in some decades to absent in other periods of the study. Finally, while females were less likely to disperse, female dispersal was more density-dependent than male dispersal. Our study shows that the relationship between density and dispersal is not temporally static and that investigations of density-dependent dispersal should consider both local and regional population densities.

scholarly journals Lack of Anonymity and Secondary Traumatic Stress in Rural Nurses

2021 ◽  
Vol 21 (1) ◽  
pp. 183-201
Author(s):  
Marilyn A. Swan ◽  
Barbara B. Hobbs
Keyword(s):  
Population Density ◽  
Traumatic Stress ◽  
Secondary Traumatic Stress ◽  
Secondary Trauma ◽  
Health Care Facilities ◽  
Population Densities ◽  
Rural Nursing ◽  
The Social ◽  
Rural Nurses ◽  
The Relationship

Purpose:  The purpose was to determine the prevalence of lack of anonymity (LA) and secondary traumatic stress (STS) among nurses; determine if nurses’ LA and STS differ by population density and examine the relationship between lack of anonymity and STS. Design and Method:  A descriptive correlational study examined LA and STS in a random sample of 271 nurses from counties with differing population densities (rural, micropolitan and metropolitan) of a Midwestern US State.  A 3-group design was used to examine the relationship between LA and STS in nurses, living and working in these counties. Data on lack of anonymity, secondary trauma and demographics were collected through online questionnaires.   Findings:  Rural nurses had a higher prevalence of LA than micropolitan and metropolitan nurses.  While the prevalence of STS among rural nurses was higher than either micropolitan or metropolitan nurses; there was no difference in STS among the three population groups.  Lack of anonymity and STS were related; however, analysis revealed that LA and STS are inversely correlated, indicating that as LA increases, STS decreases.  A majority of rural nurses (90%) reported living in a rural community prior to their 18th birthday. Conclusions:  Rural nurses experience STS at similar rates as their metropolitan and micropolitan counterparts, indicating that population density may not be a factor related to the development of STS. LA appears to have a positive effect on reducing STS in rural nurses. Clinical Relevance:  The study advanced the understanding of LA and STS among nurses who live and work in different population densities.  The social support within rural health care facilities and communities may play a role in mitigating the effects of indirect stress. Keywords: rural, rural nursing, lack of anonymity, traumatic stressDOI:  https://doi.org/10.14574/ojrnhc.v21i1.651  

Occurrence and distribution of cowpea damping-off and stem rot and associated fungi in Benin

2004 ◽  
Vol 142 (5) ◽  
pp. 561-566 ◽  
Author(s):  
A. ADANDONON ◽  
T. A. S. AVELING ◽  
M. TAMO
Keyword(s):  
Cultural Practices ◽  
Disease Incidence ◽  
Sclerotium Rolfsii ◽  
Pythium Ultimum ◽  
Common Species ◽  
Wide Distribution ◽  
Stem Rot ◽  
Damping Off ◽  
Ecological Zones ◽  
Republic Of Benin

Damping-off and stem rot of cowpea is an important soil-borne disease worldwide. Cowpea fields were randomly chosen in each agro-ecological zone in Benin and surveyed in 2001 and 2002 to determine the occurrence of the diseases throughout the country. Diseased plants, prevailing environmental conditions and cowpea grower cultural practices were recorded and causal agents associated with the disease identified. Results indicated that damping-off and stem rot were distributed throughout Benin. The disease incidence was higher in the South (0·074) and Centre zones (0·063) than in the other zones (<0·02) in the country. Among factors influencing the disease incidence, cultural practices such as sole crop and no-till systems appeared to be most important. Isolated fungi included Sclerotium rolfsii, Fusarium spp., Pythium ultimum, Rhizoctonia solani, Phoma sp., Rhizopus sp. and Trichoderma harzianum. None of the Fusarium, T. harzianum or Rhizopus sp. isolates were pathogenic in the greenhouse. Pythium ultimum, R. solani and Phoma sp. were infrequently isolated and few isolates caused the disease symptoms in the greenhouse. However, this is the first report of Phoma sp. causing damping-off and stem rot of cowpea in Benin. Sclerotium rolfsii was by far the most common species isolated from all the agro-ecological zones and all isolates were pathogenic on cowpea in the greenhouse. Sclerotium rolfsii was considered to be the main causal agent of cowpea damping-off and stem rot in the Republic of Benin due to its wide distribution, high incidence and predominance on plants with damping-off and stem rot symptoms.

Mucuna deeringiana (Bort) Merr. vs. the corm weevil, Cosmopolites sordidus Germar (Coleoptera: Curculionidae), in plantains

1969 ◽  
Vol 89 (3-4) ◽  
pp. 201-210
Author(s):  
Amparo Salazar ◽  
Alberto Pantoja ◽  
Juan Ortiz
Keyword(s):  
Population Dynamics ◽  
Population Density ◽  
Management Practices ◽  
Production Costs ◽  
Cosmopolites Sordidus ◽  
Adult Density ◽  
High Population Density ◽  
Population Densities ◽  
Insect Density ◽  
The Relationship

The effect of the legume Mucuna deeringiana on Cosmopolites sordidus population dynamics and damage was studied in two planting systems: intercropping with mucuna and mucuna as green mulch before establishing the plantain. The relationship between C. sordidus adult density and larval damage was also studied. The presence of M. deeringiana affected the incidence of C. sordidus.The data suggest that C. sordidus adults are attracted by M. deeringiana, but additional studies are needed to better understand the relationship between the legume and the insect. The presence of M. deeringiana did not affect plantain height, stem diameter, or sucker production if the legume was eliminated four months after planting. However, management practices to establish and cultivate the legume increased production costs. Although C. sordidus population densities were low during most of the year, a high population density was recorded from November to January. A second population explosion was recorded between June and August. The highest insect density recorded was 3.5 insects per trap.

scholarly journals Relationship between Alternaria radicina soil population density and carrot black rot

2009 ◽  
Vol 62 ◽  
pp. 405-405
Author(s):  
R.S. Trivedi ◽  
J. Townshend ◽  
M.V. Jaspers ◽  
H.J. Ridgway ◽  
J.G. Hampton
Keyword(s):  
Population Density ◽  
Rating Scale ◽  
Disease Incidence ◽  
Dilution Method ◽  
Black Rot ◽  
Soilborne Pathogen ◽  
Soil Population ◽  
Rot Disease ◽  
The Relationship ◽  
Soil Dilution

Alternaria radicina is a seed and soilborne pathogen that causes black rot of carrot tap roots and black rings on the root crown The A radicina population density in spring was determined in carrot field soils to investigate the relationship between soil conidial populations and black rot levels in summer In each of 15 carrot fields four randomly selected 30 m2 plots were used for soil sampling to a depth of 5 cm in September Alternaria radicina population densities (cfu/g soil) were determined using a soil dilution method and selective agar Black rot disease incidence was expressed as the number of infected plants/m of row and severity was assessed using a 0 to 4 rating scale Alternaria radicina soil population density (33233 cfu/g soil) correlated positively (P

scholarly journals Social Capital Mediates the Relationship between Social Distancing and COVID-19 Prevalence in Japan

2021 ◽  
Vol 58 ◽  
pp. 004695802110051
Author(s):  
Keisuke Kokubun ◽  
Yoshinori Yamakawa
Keyword(s):  
Social Capital ◽  
Population Density ◽  
Infection Rate ◽  
Statistical Data ◽  
Infection Rates ◽  
Population Densities ◽  
Social Distancing ◽  
Value Sharing ◽  
Increasing Trend ◽  
The Relationship

The threat of coronavirus disease (COVID-19) is increasing. Regarding the differences in the infection rate observed in each region, additionally to studies investigating the causes of differences in population density as a proxy for social distancing, an increasing trend of studies investigating the causes of differences in social capital has also been seen (ie, value sharing, acceptance of norms, unity, and trust through reciprocity). However, studies investigating whether social capital that controls the effects of population density also influences the infection rate are limited. Therefore, in this study, we analyzed the relationship between infection rate, population density, and social capital using statistical data of Japan’s every prefecture. Statistical analysis showed that social capital not only negatively correlates with infection rates and population densities, but also negatively correlates with infection rates controlling for the effects of population density. Additionally, controlling the relationship between the variables by mean age showed that social capital had a greater correlation with infection rate than population density. In other words, social capital mediates the relationship between population density and infection rates, indicating that social distancing alone is not enough to deter coronavirus disease; social capital needs to be recharged.

Gebirgswaldpflege – es kommt auf den Standort an | Mountain silviculture – it all depends on the site

2001 ◽  
Vol 152 (5) ◽  
pp. 169-176 ◽  
Author(s):  
Monika Frehner
Keyword(s):  
Nature Conservation ◽  
Low Temperature ◽  
Tree Species ◽  
Forest Stand ◽  
Ground Vegetation ◽  
Mountain Forests ◽  
Research Projects ◽  
Snow Mould ◽  
The Relationship ◽  
Protection Forests

The article shows that knowledge of the site of a particular forest stand, together with research results and experience, can provide information that is important for the cultivation of mountain forests, including knowledge of the composition of the tree species and the structure and growth capacity of natural forest. Furthermore, certain sites can, thus, be characterized by factors that influence restocking, such as snow mould,lush ground vegetation or low temperature. The guidelines«minimale Pflegemassnahmen» – «Minimal tending of protection forests» (WASSER und FREHNER, 1996) are based on this principle. For individual sites, warnings about natural dangers such as rock fall or statements concerning nature conservation can be made (e.g., the occurrence of tree species, suitability as a biotope for Capercaille). In conclusion, two research projects on the relationship between site and natural dangers will be presented.

Optimization and Quality by Design Approach for Piroxicam Fast Dissolving Tablet Formulations Using Box-Behnken Design

2020 ◽  
Vol 15 (2) ◽  
pp. 152-165
Author(s):  
Harekrishna Roy ◽  
Sisir Nandi ◽  
Ungarala Pavani ◽  
Uppuluri Lakshmi ◽  
Tamma Saicharan Reddy ◽  
...  
Keyword(s):  
Quality By Design ◽  
Methyl Cellulose ◽  
Statistical Technique ◽  
Quadratic Model ◽  
Contour Plot ◽  
Compression Technique ◽  
Disintegration Time ◽  
Box Behnken Design ◽  
The Impact ◽  
The Relationship

Background: The present study deals with the formulation and optimization of piroxicam fast dissolving tablets and analyzes the impact of an independent variable while selecting the optimized formulation utilizing Quality by Design (QbD) and Box-Behnken Design (BBD). Methods: Seventeen formulations were prepared by direct compression technique by altering the proportion of cross carmellose sodium, spray dried lactose and hydro propyl methyl cellulose (HPMC K4M). The BBD statistical technique was used to optimize formulations and correlate the relationship among all the variables. Also, the powder mixture characteristics and tablet physiochemical properties such as hardness, friability, drug content, Disintegration Time (DT) and dissolution test were determined using 900 ml of 0.1N HCl (pH-1.2) at 37 ± 0.5°C. Results: Significant quadratic model and second order polynomial equations were established using BBD. To find out the relationship between variables and responses, 3D response surface and 2D contour plot was plotted. A perturbation graph was also plotted to identify the deviation of the variables from the mean point. An optimized formula was prepared based on the predicted response and the resulting responses were observed to be close with the predicted value. Conclusion: The optimized formulation with the desired parameter and formulation with variables and responses can be obtained by BBD and could be used in the large experiment with the involvement of a large number of variables and responses.

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