Cadmium variability in leaves of a Salix fragilis: simulation and implications for leaf sampling

2001 ◽  
Vol 31 (2) ◽  
pp. 313-321 ◽  
Author(s):  
S Luyssaert ◽  
M Van Meirvenne ◽  
N Lust
Keyword(s):  
Sampling Strategy ◽  
Dry Mass ◽  
Sampling Procedure ◽  
Pollution Level ◽  
Salix Fragilis ◽  
Indicator Simulation ◽  
Leaf Sampling ◽  
Current Sampling ◽  
Cd Distribution ◽  
Sun Leaves

Plant analysis is a valuable tool to evaluate the pollution level. However, leaf sampling is complicated because of the high variability within the crown. To investigate the variability of cadmium (Cd) in the leaves of a tree, we sampled one Salix fragilis L. at 292 locations, each with a volume of 0.3 × 0.3 × 0.3 m. The Cd concentration was found to be normally distributed within a range from 2.4 to 10.6 mg·kg–1 dry mass (DM), with an average of 6.3 mg·kg–1 DM. A trend was found with high values in the lower parts of the crown and low Cd concentrations at the top. After removal of this trend the residuals showed a clear spatial structure modelled by a variogram. The Cd distribution in the leaves of the entire tree was predicted by sequential indicator simulation. These results were used to evaluate the current sampling strategy for tree leaves, i.e., sampling sun leaves of the upper third of the tree crown. The latter procedure was found to yield biased estimates of the average Cd concentration as well as the risk of exceeding a contamination threshold. An alternative sampling procedure is proposed. This procedure investigates whether a trend is present. Once the height where sampling will result in a correct statement of the tree's pollution is located, the rest of the stand could be sampled at this height.

Sun-shade patterns of leaf carotenoid composition in 86 species of neotropical forest plants

2009 ◽  
Vol 36 (1) ◽  
pp. 20 ◽  
Author(s):  
Shizue Matsubara ◽  
G. Heinrich Krause ◽  
Jorge Aranda ◽  
Aurelio Virgo ◽  
Kim G. Beisel ◽  
...  
Keyword(s):  
Woody Species ◽  
Carotenoid Biosynthesis ◽  
Dry Mass ◽  
Daily Basis ◽  
High Irradiance ◽  
Strong Light ◽  
Neotropical Forest ◽  
Forest Plants ◽  
Shade Leaves ◽  
Sun Leaves

A survey of photosynthetic pigments, including 86 species from 64 families, was conducted for leaves of neotropical vascular plants to study sun-shade patterns in carotenoid biosynthesis and occurrence of α-carotene (α-Car) and lutein epoxide (Lx). Under low light, leaves invested less in structural components and more in light harvesting, as manifested by low leaf dry mass per area (LMA) and enhanced mass-based accumulation of chlorophyll (Chl) and carotenoids, especially lutein and neoxanthin. Under high irradiance, LMA was greater and β-carotene (β-Car) and violaxanthin-cycle pool increased on a leaf area or Chl basis. The majority of plants contained α-Car in leaves, but the α- to β-Car ratio was always low in the sun, suggesting preference for β-Car in strong light. Shade and sun leaves had similar β,ε-carotenoid contents per unit Chl, whereas sun leaves had more β,β-carotenoids than shade leaves. Accumulation of Lx in leaves was found to be widely distributed among taxa: >5 mmol mol Chl−1 in 20% of all species examined and >10 mmol mol Chl−1 in 10% of woody species. In Virola elongata (Benth.) Warb, having substantial Lx in both leaf types, the Lx cycle was operating on a daily basis although Lx restoration in the dark was delayed compared with violaxanthin restoration.

Development of a leaf sampling technique and leaf standards for kiwifruit in New South Wales

1989 ◽  
Vol 29 (3) ◽  
pp. 411 ◽  
Author(s):  
GC Cresswell
Keyword(s):  
New South ◽  
New South Wales ◽  
Sampling Technique ◽  
Sampling Procedure ◽  
Nutrient Composition ◽  
Actual Performance ◽  
Leaf Analysis ◽  
Growing Seasons ◽  
South Wales ◽  
Leaf Sampling

The nutrient composition of foliage from mature vines of the kiwifruit varieties, Hayward and Bruno was monitored monthly over 3 consecutive growing seasons in an orchard on the central coast of New South Wales. Within a season, concentrations of N (5.07-2.74%), P (1.0-0.44%), K (3.29-1.95%) and Zn (36-19 mg/kg) in the first leaf after the fruit generally declined while concentrations of Ca (1.4 1 - 4.21%), Mg(0.28-0.50%) and Mn (151-275 mg/kg) increased. Leaf composition was relatively stable in February and this is proposed as a suitable standard sampling time for leaf analysis in New South Wales. Only minor differences in nutrient composition were found between the first leaf and other potential index leaves remaining on shoots at this time. Using this leaf sampling procedure, commercial kiwifruit orchards in New South Wales were surveyed over 3 consecutive seasons. The applicability of the New Zealand leaf analysis standards for use in New South Wales was assessed by comparing the predicted and actual performance of orchards in the survey. Where unreasonable divergence between the two was noted the standards were amended to make them more relevant to field conditions in New South Wales.

Tree age-related effects on sun acclimated leaves in a chronosequence of beech (Fagus sylvatica) stands

2012 ◽  
Vol 39 (4) ◽  
pp. 323 ◽  
Author(s):  
Juliette Louis ◽  
Hélène Genet ◽  
Sylvie Meyer ◽  
Kamel Soudani ◽  
Pierre Montpied ◽  
...  
Keyword(s):  
Fagus Sylvatica ◽  
Leaf Size ◽  
Dry Mass ◽  
Leaf Nitrogen ◽  
Tree Age ◽  
Stand Age ◽  
Leaf Mass ◽  
Age Related ◽  
Sun Leaves

The assessment of the effect of tree age on leaves is usually limited by the difficulty of sampling sun leaves from tall ageing trees. In this study, we investigated tree age-related effects on sun leaves in a chronosequence of beech (Fagus sylvatica L.) stands. The effects of stand age on leaf mass to area ratio (LMA), chlorophyll (Chl), epidermal polyphenols (EPhen), nitrogen and carbon contents in sun leaves were investigated in 17 even-aged stands distributed into six age classes (14–175 years old). Chl and EPhen were assessed in vivo with SPAD and Dualex portable leaf-clips respectively. Leaves were sampled by shooting and sun leaves were identified based on criteria obtained from a vertical profile of the ratio abaxial vs adaxial EPhen across the canopy. Sun leaves were characterised by a high and similar adaxial and abaxial EPhen contents, high LMA value and low mass-based Chl content. These sun leaf characteristics, together with leaf nitrogen and carbon contents, were not significantly affected by stand age. Along the chronosequence, beech trees invested a stable fraction of leaf mass into nitrogen, carbon, Chl and EPhen with decreasing leaf size, i.e. dry mass and area.

scholarly journals Household expenses in healthcare and its coping mechanism in rural Nepal

2021 ◽  
Vol 8 (10) ◽  
pp. 4750
Author(s):  
Aliza Shrestha ◽  
Susmita Nepal ◽  
Aassmi Poudyal
Keyword(s):  
Health Care ◽  
Household Head ◽  
Sampling Strategy ◽  
Health Care Expenditures ◽  
Sampling Procedure ◽  
Bivariate Analysis ◽  
Household Expenditure ◽  
Coping Mechanism ◽  
Cross Sectional ◽  
Study Region

Background: In Nepal, the most frequent mode of payment for health care is household expenditure. It accounts for more than half of all health-care expenditures. In addition, the study intends to investigate household expenditure on health care and its coping mechanisms in Nepal's rural districts.Methods: This is a quantitative, cross-sectional study in which 410 households were chosen using a multiple sampling procedure. The research study region was chosen using a purposive sampling strategy. The two wards for the study were chosen by a lottery system. The estimated households were then chosen using a systematic random selection technique. A semi-structured questionnaire was utilized to gather data, and a face-to-face interview with the household head was undertaken to obtain the data. SPSS version 20 was used to analyze all of the data.Results: The overall household health expenditure in Miklajung rural municipality was determined to be 31.7% in the previous six months, with the biggest expenditure in medicine/drugs or pharmacies, followed by in-patient care and health treatment abroad. Income/savings was discovered to be a major coping mechanism used to deal with household expenditure and was found to be significantly associated in a bivariate analysis with type of illness, age, and more with a confidence interval of 95% in a bivariate analysis.Conclusions: At the conclusion of the investigation, we discovered that people spent the most money on medicines and drugs, followed by in-patient hospital care. According to the findings, a significant portion of the target group used their income and savings to cover unexpected healthcare costs.

Linked Pairs of Bereayed Persons: A Method for Increasing the Sample Size in a Study of Bereavement

1986 ◽  
Vol 16 (2) ◽  
pp. 141-153 ◽  
Author(s):  
Shirley A. Murphy ◽  
Barbara J. Stewart
Keyword(s):  
Statistical Analysis ◽  
High Risk ◽  
Natural Disaster ◽  
Sampling Strategy ◽  
Sampling Procedure ◽  
Coping Responses ◽  
Independent Observations ◽  
And Coping ◽  
Study Questionnaire ◽  
Selection Of

Methods of obtaining representative and adequate sized samples from potentially high-risk bereaved persons have had limited discussion in the literature. This article describes a sampling strategy used to obtain bereaved respondents for a study designed to examine loss and coping responses following a recent natural disaster. Linked pairs of persons, that is, the selection of two bereaved participants for each deceased disaster victim lessened a potential sampling dilemma. However, it cannot be assumed that study questionnaire scores obtained from the linked pairs are indeed independent observations. The statistical analysis used to support the independence of scores between the pairs is delineated. Thus, the sampling procedure appeared not to produce an obvious bias and was very beneficial in meeting the research objectives.

scholarly journals Relative free-energy calculations for scaffold hopping-type transformations with an automated RE-EDS sampling procedure

2022 ◽  
Author(s):  
Benjamin Ries ◽  
Karl Normak ◽  
R. Gregor Weiß ◽  
Salomé Rieder ◽  
Emília P. Barros ◽  
...  
Keyword(s):  
Free Energy ◽  
Computational Cost ◽  
Sampling Strategy ◽  
Energy Difference ◽  
Sampling Procedure ◽  
Free Energy Calculations ◽  
Ease Of Use ◽  
State Graph ◽  
Scaffold Hopping ◽  
Relative Free Energy

AbstractThe calculation of relative free-energy differences between different compounds plays an important role in drug design to identify potent binders for a given protein target. Most rigorous methods based on molecular dynamics simulations estimate the free-energy difference between pairs of ligands. Thus, the comparison of multiple ligands requires the construction of a “state graph”, in which the compounds are connected by alchemical transformations. The computational cost can be optimized by reducing the state graph to a minimal set of transformations. However, this may require individual adaptation of the sampling strategy if a transformation process does not converge in a given simulation time. In contrast, path-free methods like replica-exchange enveloping distribution sampling (RE-EDS) allow the sampling of multiple states within a single simulation without the pre-definition of alchemical transition paths. To optimize sampling and convergence, a set of RE-EDS parameters needs to be estimated in a pre-processing step. Here, we present an automated procedure for this step that determines all required parameters, improving the robustness and ease of use of the methodology. To illustrate the performance, the relative binding free energies are calculated for a series of checkpoint kinase 1 inhibitors containing challenging transformations in ring size, opening/closing, and extension, which reflect changes observed in scaffold hopping. The simulation of such transformations with RE-EDS can be conducted with conventional force fields and, in particular, without soft bond-stretching terms.

scholarly journals Adequate sampling, an important step towards reliable decisions based on analytical results

2017 ◽  
pp. 16
Author(s):  
Lennart Mathiasson ◽  
Lennart Mårtensson
Keyword(s):  
Sampling Site ◽  
Sampling Strategy ◽  
Sampling Procedure ◽  
Research Projects ◽  
Treatment Processes ◽  
Inorganic Species ◽  
Scientific Principles ◽  
Adequate Sampling ◽  
The Individual ◽  
And Control

The efforts spent on judgments of how to perform sampling are often small compared to other steps in the analytical procedure. As a result decisions may be based on irrelevant results. If the sampling is intended to provide information how to reduce and control environmental pollution, it is important to design the sampling strategy according to scientific principles. Sampling will be discussed in relation to determinations of organic as well as inorganic species in different types of polluted matrices, .e.g. water, sediments and air. Examples will be taken from our own research projects about treatment processes for contaminated matrices. Accurate sampling involves a basic planning including objectives, cost effectiveness versus the budget, variability of contamination leading to statistical considerations, site accessibility and robustness of the used devices. A strategy for the sampling, often in a form of a scheme, is needed. The Laqua Protocol developed within our research projects will be presented. This protocol is flexible and dynamic and can be altered and optimized based on the demands at the individual sampling site. Sampling of complicated matrices often creates problems with interfering agents and breakdown of unstable analytes. In this type of samples the concentrations of analytes are generally several orders of magnitudes lower than the concentrations of major constituents in the sample. Accordingly the advantages of an early work-up, preferably in connection with a sampling procedure, is paid especially attention

Opening images of synaptic vesicles and calcium localization by means of microwave fixation method

1990 ◽  
Vol 48 (2) ◽  
pp. 182-183
Author(s):  
Vinci Mizuhira ◽  
Hiroshi Hasegawa
Keyword(s):  
Synaptic Vesicles ◽  
Room Temperature ◽  
Osmium Tetroxide ◽  
Sampling Procedure ◽  
Fixation Method ◽  
Potassium Oxalate ◽  
X Ray ◽  
Cacodylate Buffer ◽  
Ultrathin Sections ◽  
Microwave Fixation

Microwave irradiation (MWI) was applied to 0.3 to 1 cm3 blocks of rat central nervous system at 2.45 GHz/500W for about 20 sec in a fixative, at room temperature. Fixative composed of 2% paraformaldehyde, 0.5% glutaraldehyde in 0.1 M cacodylate buffer at pH 7.4, also contained 2 mM of CaCl2 , 1 mM of MgCl2, and 0.1% of tannic acid for conventional observation; and fuether 30-90 mM of potassium oxalate containing fixative was applied for the detection of calcium ion localization in cells. Tissue blocks were left in the same fixative for 30 to 180 min after MWI at room temperature, then proceeded to the sampling procedure, after postfixed with osmium tetroxide, embedded in Epon. Ultrathin sections were double stained with an useal manner. Oxalate treated sections were devided in two, stained and unstained one. The later oxalate treated unstained sections were analyzed with electron probe X-ray microanalyzer, the EDAX-PU-9800, at 40 KV accelerating voltage for 100 to 200 sec with point or selected area analyzing methods.

STEM measurement of subcellular water distributions

1993 ◽  
Vol 51 ◽  
pp. 568-569
Author(s):  
R.D. Leapman ◽  
S.Q. Sun ◽  
S-L. Shi ◽  
R.A. Buchanan ◽  
S.B. Andrews
Keyword(s):  
Water Content ◽  
Internal Standard ◽  
Dry Weight ◽  
Dry Mass ◽  
Scanning Transmission Electron Microscope ◽  
Dark Field ◽  
Bulk Water ◽  
Inelastic Electron ◽  
Scanning Transmission ◽  
Annular Dark Field

Recent advances in rapid-freezing and cryosectioning techniques coupled with use of the quantitative signals available in the scanning transmission electron microscope (STEM) can provide us with new methods for determining the water distributions of subcellular compartments. The water content is an important physiological quantity that reflects how fluid and electrolytes are regulated in the cell; it is also required to convert dry weight concentrations of ions obtained from x-ray microanalysis into the more relevant molar ionic concentrations. Here we compare the information about water concentrations from both elastic (annular dark-field) and inelastic (electron energy loss) scattering measurements.In order to utilize the elastic signal it is first necessary to increase contrast by removing the water from the cryosection. After dehydration the tissue can be digitally imaged under low-dose conditions, in the same way that STEM mass mapping of macromolecules is performed. The resulting pixel intensities are then converted into dry mass fractions by using an internal standard, e.g., the mean intensity of the whole image may be taken as representative of the bulk water content of the tissue.

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