The Effect of Microsite Variation on Seed-Germination and Seedling Survival of Eucalyptus delegatensis

1993 ◽  
Vol 41 (2) ◽  
pp. 169 ◽  
Author(s):  
M Battaglia ◽  
JB Reid
Keyword(s):  
Seed Germination ◽  
Seedling Survival ◽  
Soil Conditions ◽  
Small Scale ◽  
Root Penetration ◽  
Mean Survival Time ◽  
The Mean ◽  
Developmental Characteristics ◽  
The Impact ◽  
Eucalyptus Delegatensis

The correlation between microsite and seedling numbers was determined in field sowings, and the impact of microsites on germination and seedling survival tested in artificial seedbeds in the glasshouse. Small scale variation in soil conditions, at the scale of tens of centimetres, markedly affected the germination and establishment of Eucalyptus delegatensis R.T.Baker seeds and seedlings. Under conditions of limiting soil moisture, microsites that afforded protection, and probably resulted in increased humidity, caused a marked increase in germination number and rate. The mean survival time was significantly higher on these protected microsites than on less protected microsites, or on microsites that restricted root penetration. The importance of this variability in microtopography was strongly influenced by season and the level of environmental stress, and was diminished as seedlings aged. Due to the different requirements for seed germination and seedling growth, a favourable microsite for germination was not necessarily a favourable site for seedling survival. A comparison of seed and seedling responses to water stress indicated that for E. delegatensis, at least, selection due to microsite differences at the time of germination may not have an impact on the developmental characteristics of the seedlings.

scholarly journals Depression, Suicidal Ideation, and Resilience among Rural Farmers in a Drought-Affected Area of Trichy District, Tamil Nadu

2019 ◽  
Vol 10 (02) ◽  
pp. 238-244 ◽  
Author(s):  
Deepak Justine Viswanathan ◽  
Veerakumar A. M ◽  
Hemalatha Kumarasamy
Keyword(s):  
Suicidal Ideation ◽  
Tamil Nadu ◽  
Pearson Correlation ◽  
Small Scale ◽  
Cluster Sampling ◽  
Years Of Experience ◽  
Affected Area ◽  
Prevalence Of Depression ◽  
The Mean ◽  
The Impact

ABSTRACTBackground: Changes in climatic conditions and other factors including trade and commerce have influenced agriculture worldwide. These factors have created a crisis among farmers. Objectives: The objective of this study was to find out the prevalence of depression and suicidal ideation, to measure the resilience, and to find out the factors that influence depression and resilience among farmers. Materials and Methods: A community-based cross-sectional analytical study was performed among farmers residing in a drought-affected area of Tiruchirappalli district of Tamil Nadu. The sample size was 191 and cluster sampling was used to select the participants. Structured, pretested questionnaires were used to find the prevalence of depression, suicidal ideation, and resilience among farmers. Pearson Correlation, Student’s t-test, analysis of variance, and Pearson Chi-square test were used to identify the factors influencing depression and resilience. Results: A total of 194 farmers participated in the study. The mean age of the farmers was 46.68 ± 12.6 years, majority 64% were males and 89% were literates. Among the participants, 97.4% had some form of depression, and 67% had severe depression. About 60% of the farmers had suicidal ideation. Male farmers, farmers with few years of farming experience, and severe reduction in yield had a higher level of depression. Suicidal ideation was influenced by gender, small-scale farming, fewer years of experience in farming, and the impact of drought on yield. The mean resilience score was 49.4 ± 10. Gender and years of experience in farming had a significant association with resilience. Conclusion: High prevalence of depression and suicidal ideation and low level of resilience has been observed among the farmers. Interventions need to be provided for marginal and small-scale farmers, male farmers in the affected area to reduce the impact of drought in these farmers.

scholarly journals Small-Scale Drop Size Variability: Impact on Estimation of Cloud Optical Properties

2005 ◽  
Vol 62 (7) ◽  
pp. 2555-2567 ◽  
Author(s):  
Y. Knyazikhin ◽  
R. B. Myneni ◽  
A. Marshak ◽  
W. J. Wiscombe ◽  
M. L. Larsen ◽  
...  
Keyword(s):  
Drop Size ◽  
Water Drop ◽  
Small Scale ◽  
Size Dependent ◽  
Radiative Impact ◽  
Size Variability ◽  
The Mean ◽  
Conventional Models ◽  
Processing Techniques ◽  
The Impact

Abstract Most cloud radiation models and conventional data processing techniques assume that the mean number of drops of a given radius is proportional to volume. The analysis of microphysical data on liquid water drop sizes shows that, for sufficiently small volumes, this proportionality breaks down; the number of cloud drops of a given radius is instead proportional to the volume raised to a drop size–dependent nonunit power. The coefficient of proportionality, a generalized drop concentration, is a function of the drop size. For abundant small drops the power is unity as assumed in the conventional approach. However, for rarer large drops, it falls increasingly below unity. This empirical fact leads to drop clustering, with the larger drops exhibiting a greater degree of clustering. The generalized drop concentration shows the mean number of drops per cluster, while the power characterizes the occurrence frequency of clusters. With a fixed total number of drops in a cloud, a decrease in frequency of clusters is accompanied by a corresponding increase in the generalized concentration. This initiates a competing process missed in the conventional models: an increase in the number of drops per cluster enhances the impact of rarer large drops on cloud radiation while a decrease in the frequency suppresses it. Because of the nonlinear relationship between the number of clustered drops and the volume, these two opposite tendencies do not necessarily compensate each other. The data analysis suggests that clustered drops likely have a stronger radiative impact compared to their unclustered counterpart; ignoring it results in underestimation of the contribution from large drops to cloud horizontal optical path.

PP20 A retrospective service evaluation of the presentation of anaphylaxis to a UK ambulance service

2019 ◽  
Vol 36 (10) ◽  
pp. e9.2-e9
Author(s):  
Nicholas Groom ◽  
Sarah Taylor ◽  
Ed England ◽  
Helen Pocock ◽  
Charles D Deakin
Keyword(s):  
Service Evaluation ◽  
Ambulance Service ◽  
Small Scale ◽  
Patient Records ◽  
Electronic Patient Records ◽  
Self Administration ◽  
Patient Demographics ◽  
The Mean ◽  
The Impact ◽  
To Receive

BackgroundThere is a lack of data relating to frequency and presentation of anaphylaxis to the ambulance service in England. Little research exists relating to the patients’ self-treatment of anaphylaxis and there is an absence of evidence to evaluate the impact of self-administered adrenaline, there is a need to describe this patient group to evaluate any potential to develop their care.MethodsRetrospective data were collected from the electronic patient records of a single NHS ambulance service serving a population of approximately four million. Records between 1stApril 2017 and 31st March 2018 were included where a diagnosis of anaphylaxis was recorded. Gender, age, incident location, allergy history, were summarised to identify any trends in presentation. The frequency of patient self-administration, as well as ambulance administration, of adrenaline was also included for analysis to determine any correlation.Results326 records were included in the analysis. The mean, median and modal patient ages were 34, 29 and 20 respectively. Patient ages ranged from six months to 95 years. Patients were 65% female, 35% male and 59% of incidents occurred at home. 76% of patients reported having a known allergy with food being the most common allergen (44%). Peak times for calling 999 were midday and 6pm. 35% of patients had self-administered adrenaline. 52% received ambulance-administered adrenaline. The doses of self-administered adrenaline ranged from 0–3 doses and ambulance administered adrenaline ranged from 0–8 doses. Patients who self-administered adrenaline were less likely to receive further adrenaline from the ambulance service. No correlation was found between the number of self-administered doses and ambulance administered doses.ConclusionPatient demographics such as age, gender and allergies were consistent with two previous small-scale studies. This study suggests that early self-administration of adrenaline is beneficial. Opportunities for improvements in data recording as well as patient education were identified.

Sources of spatial and temporal heterogeneity in the colonization of an alpine krummholz environment by the weedy subalpine plant Chamerion angustifolium (fireweed)

2006 ◽  
Vol 84 (6) ◽  
pp. 933-939 ◽  
Author(s):  
Amy J. Dona ◽  
Candace Galen
Keyword(s):  
Soil Moisture ◽  
Seed Germination ◽  
Rocky Mountains ◽  
Seedling Survival ◽  
Water Status ◽  
Adult Life ◽  
Life History Stage ◽  
Chamerion Angustifolium ◽  
Moisture Variation ◽  
The Impact

Plant–plant interactions may increase or reduce the impact of abiotic stress on species' distributions, depending on the balance between competition and facilitation. We report on the role of a willow ( Salix ) shrub canopy in mediating the importance of drought stress for performance at seedling and adult life stages of the herbaceous wildflower, Chamerion angustifolium L. (fireweed). Willows form the vegetative boundary (krummholz) between subalpine and alpine life zones in the Rocky Mountains. Chamerion angustifolium is a weedy pioneer species common in subalpine vegetation and advancing upward into the krummholz in the central Rocky Mountains. A mosaic of soil moisture variation dictated spatial patterns of seed germination and seedling survival in C. angustifolium in the absence of willows. However, willows restricted the capacity of C. angustifolium to exploit natural patches of soil moisture during establishment. Seed germination, seedling survival, and net establishment success increased markedly with soil water supply in the open, but not under the willow canopy. For mature plants, willows restricted photosynthesis at the peak of the growing season when rainfall was frequent, but ameliorated the daily decline in leaf water status under drought late in the season. Results suggest that the impact of willows on desiccation stress in alpine populations of fireweed varies with life history stage and phenology.

scholarly journals Performance of Conservation Techniques for Semiarid Environments: Field Observations with Caatinga, Mulch, and Cactus Forage Palma

Water ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 792 ◽  
Author(s):  
Iug Lopes ◽  
Abelardo A. A. Montenegro ◽  
João L. M. P. de Lima
Keyword(s):  
Vegetation Cover ◽  
Soil Conservation ◽  
Bare Soil ◽  
Natural Vegetation ◽  
Soil Reclamation ◽  
Soil Conditions ◽  
Small Scale ◽  
The Impact ◽  
Semi Arid ◽  
Soil Losses

Understanding small-scale hydrologic processes and the impact of soil conservation techniques are crucial in reducing runoff and sediment losses in semi-arid regions. This study was conducted in the Alto Ipanema River Basin, in Pernambuco State (Brazil). Soil and water dynamics were intensely monitored in twelve experimental plots with different coverage conditions (plot with bare soil—Bare; plot with natural vegetation—Natur; plot with mulch—Mulch; plot with Cactus Palma—Palma). By far, bare soil conditions produced higher runoff and soil losses. Mulch cover was close to natural vegetation cover, but still presented higher runoff and sediment losses. Palma, which is a very popular spineless cactus for animal feed in the Brazilian semi-arid region, presented an intermediate hydrologic impact in controlling runoff, enhancing soil moisture, and also reducing soil losses. Experiments were conducted in one hydrologic year (2016/2017) at three different sites. They were intensely monitored and had the same number of plots. This enabled us to carry out a robust performance assessment of the two soil conservation practices adopted (Mulch and Palma), compared to natural vegetation cover and bare soil conditions. Such low-cost alternatives could be easily adopted by local farms in the region, and, hence, improve soil reclamation and regional resiliency in a water-scarce environment.

Seed Germination Model for Eucalyptus delegatensis Provenances Germinating under Conditions of Variable Temperature and Water Potential

1997 ◽  
Vol 24 (1) ◽  
pp. 69 ◽  
Author(s):  
M. Battaglia
Keyword(s):  
Water Stress ◽  
Seed Germination ◽  
Water Potential ◽  
Threshold Model ◽  
Soil Water Potential ◽  
Regeneration Niche ◽  
Model Parameters ◽  
Base Population ◽  
The Mean ◽  
Eucalyptus Delegatensis

This paper develops a population-based threshold model to describe the combined action of sub- and supra-optimal temperatures, water stress and the release of dormancy by cool-moist stratification on the germination of seeds of Eucalyptus delegatensis R.T. Baker. Separate models were fitted for seed samples collected from five climatically differing regions. The model presumes that the time to germination of a given seed fraction is inversely proportional to the difference between the actual level of a given germination factor and the factor threshold. The model then assumes that variation in this factor threshold within a seed population as a whole can be characterised by a normal, or log-normal, distribution. By using physiological time rather than clock time as a metric, the model was extended to describe germination under varying conditions in the field. A number of applications of the model were demonstrated. The correlation of model parameters with regional climate was tested and it was concluded that site temperature affected both the mean and variation in base population sensitivities to stratification-dose but that site rainfall affected only the mean base population sensitivity to water stress with all populations having a common variance. Examination of the model parameters relating to the release of dormancy indicated that the increased germination rate associated with stratification could be accounted for by progress towards germination made at stratifying temperatures. Finally, the model was used to examine the fundamental regeneration niche of E. delegatensis and it was concluded that abundant germination in the field could only be expected when the soil water potential is above –0.4 MPa and temperatures exceed 7.5°C. The model is presented as a flexible framework that allows for the prediction of field germination and as a useful tool for exploring seed germination processes, and the fundamental regeneration niche of the species. The modelling framework is easily modified to include additional factors and factor interactions applicable to other situations and species.

Asteroid and Comet Impact Speeds upon Mars: Significance for Panspermia and the Supply of Organics

1997 ◽  
Vol 161 ◽  
pp. 197-201 ◽  
Author(s):  
Duncan Steel
Keyword(s):  
Probability Distributions ◽  
Regions Of Interest ◽  
Significant Fraction ◽  
Organic Chemicals ◽  
Impact Speed ◽  
The Mean ◽  
The Impact

AbstractWhilst lithopanspermia depends upon massive impacts occurring at a speed above some limit, the intact delivery of organic chemicals or other volatiles to a planet requires the impact speed to be below some other limit such that a significant fraction of that material escapes destruction. Thus the two opposite ends of the impact speed distributions are the regions of interest in the bioastronomical context, whereas much modelling work on impacts delivers, or makes use of, only the mean speed. Here the probability distributions of impact speeds upon Mars are calculated for (i) the orbital distribution of known asteroids; and (ii) the expected distribution of near-parabolic cometary orbits. It is found that cometary impacts are far more likely to eject rocks from Mars (over 99 percent of the cometary impacts are at speeds above 20 km/sec, but at most 5 percent of the asteroidal impacts); paradoxically, the objects impacting at speeds low enough to make organic/volatile survival possible (the asteroids) are those which are depleted in such species.

Sound Production Treatment for Acquired Apraxia of Speech: An Examination of Dosage in Relation to Probe Performance

2020 ◽  
pp. 1-16
Author(s):  
Julie L. Wambaugh ◽  
Lydia Kallhoff ◽  
Christina Nessler
Keyword(s):  
Retrospective Analysis ◽  
Sound Production ◽  
Apraxia Of Speech ◽  
Practice Schedule ◽  
Practice Schedules ◽  
Baseline Performance ◽  
The Mean ◽  
Number Of Treatment ◽  
The Impact

Purpose This study was designed to examine the association of dosage and effects of Sound Production Treatment (SPT) for acquired apraxia of speech. Method Treatment logs and probe data from 20 speakers with apraxia of speech and aphasia were submitted to a retrospective analysis. The number of treatment sessions and teaching episodes was examined relative to (a) change in articulation accuracy above baseline performance, (b) mastery of production, and (c) maintenance. The impact of practice schedule (SPT-Blocked vs. SPT-Random) was also examined. Results The average number of treatment sessions conducted prior to change was 5.4 for SPT-Blocked and 3.9 for SPT-Random. The mean number of teaching episodes preceding change was 334 for SPT-Blocked and 179 for SPT-Random. Mastery occurred within an average of 13.7 sessions (1,252 teaching episodes) and 12.4 sessions (1,082 teaching episodes) for SPT-Blocked and SPT-Random, respectively. Comparisons of dosage metric values across practice schedules did not reveal substantial differences. Significant negative correlations were found between follow-up probe performance and the dosage metrics. Conclusions Only a few treatment sessions were needed to achieve initial positive changes in articulation, with mastery occurring within 12–14 sessions for the majority of participants. Earlier occurrence of change or mastery was associated with better follow-up performance. Supplemental Material https://doi.org/10.23641/asha.12592190

Platelet Suruival and Function in Rats with Enhanced Thrombotic Tendency

1985 ◽  
Vol 54 (04) ◽  
pp. 739-743 ◽  
Author(s):  
Federica Delaini ◽  
Elisabetta Dejana ◽  
Ine Reyers ◽  
Elisa Vicenzi ◽  
Germana De Bellis Vitti ◽  
...  
Keyword(s):  
Arachidonic Acid ◽  
Nephrotic Syndrome ◽  
Platelet Function ◽  
Laboratory Tests ◽  
Thrombus Formation ◽  
The Other ◽  
Mean Survival Time ◽  
The Mean ◽  
And Function ◽  
Thrombotic Tendency

SummaryWe have investigated the relevance of some laboratory tests of platelet function in predicting conditions of thrombotic tendency. For this purpose, we studied platelet survival, platelet aggregation in response to different stimuli, TxB2 and 6-keto-PGFlα production in serum of rats bearing a nephrotic syndrome induced by adriamycin. These animals show a heavy predisposition to the development of both arterial and venous thrombosis. The mean survival time was normal in nephrotic rats in comparison to controls. As to aggregation tests, a lower aggregating response was found in ADR-treated rats using ADP or collagen as stimulating agents. With arachidonic acid (AA) we observed similar aggregating responses at lower A A concentrations, whereas at higher AA concentrations a significantly lower response was found in nephrotic rats, despite their higher TxB2 production. Also TxB2 and 6-keto-PGFlα levels in serum of nephrotic rats were significantly higher than in controls. No consistent differences were found in PGI2-activity generated by vessels of control or nephrotic rats.These data show that platelet function may appear normal or even impaired in rats with a markedly increased thrombotic tendency. On the other hand, the significance of high TxB2 levels in connection with mechanisms leading to thrombus formation remains a controversial issue.

The methodological approach for the determination of the pressure of artificial raindrops as a question of the theory of splash soil erosion

2020 ◽  
pp. 24-28
Author(s):  
Mihail Zver'kov
Keyword(s):  
Block Diagram ◽  
Methodological Approach ◽  
Control Measures ◽  
Soil Conditions ◽  
Effective Pressure ◽  
Long Distance ◽  
Splash Erosion ◽  
Rain Drops ◽  
Artificial Rain ◽  
The Impact

To the article the results of the theoretical and experimental researches are given on questions of estimates of the dynamic rate effect of raindrop impact on soil. The aim of this work was to analyze the current methods to determine the rate of artificial rain pressure on the soil for the assessment of splash erosion. There are the developed author’s method for calculation the pressure of artificial rain on the soil and the assessment of splash erosion. The study aims to the justification of evaluation methods and the obtaining of quantitative characteristics, prevention and elimination of accelerated (anthropogenic) erosion, the creation and the realization of the required erosion control measures. The paper considers the question of determining the pressure of artificial rain on the soil. At the moment of raindrops impact, there is the tension in the soil, which is called vertical effective pressure. It is noted that the impact of rain drops in the soil there are stresses called vertical effective pressure. The equation for calculation of vertical effective pressure is proposed in this study using the known spectrum of raindrops. Effective pressure was 1.4 Pa for the artificial rain by sprinkler machine «Fregat» and 5.9 Pa for long distance sprinkler DD-30. The article deals with a block diagram of the sequence for determining the effective pressure of rain drops on the soil. This diagram was created by the author’s method of calculation of the effective pressure of rain drops on the soil. The need for an integrated approach to the description of the artificial rain impact on the soil is noted. Various parameters characterizing drop erosion are considered. There are data about the mass of splashed soil in the irrigation of various irrigation machinery and installations. For example, the rate (mass) of splashed soil was 0.28…0.78 t/ha under irrigation sprinkler apparatus RACO 4260–55/701C in the conditions of the Ryazan region. The method allows examining the environmental impact of sprinkler techniques for analyzes of the pressure, caused by raindrops, on the soil. It can also be useful in determining the irrigation rate before the runoff for different types of sprinkler equipment and soil conditions.

Sign in / Sign up

Export Citation Format

Share Document