scholarly journals Convergence in hydraulic architecture, water relations and primary productivity amongst habitats and across seasons in Sydney

2004 ◽  
Vol 31 (5) ◽  
pp. 429 ◽  
Author(s):  
Catriona Macinnis-Ng ◽  
Kate McClenahan ◽  
Derek Eamus
Keyword(s):  
Water Relations ◽  
Negative Correlation ◽  
Inverse Correlation ◽  
Leaf Traits ◽  
Significant Negative Correlation ◽  
Hydraulic Architecture ◽  
Xylem Embolism ◽  
Sapwood Area ◽  
Huber Value ◽  
The Cost

Convergence in leaf traits across biomes demonstrates generality in plant functioning. Relationships between hydraulic architecture and photosynthesis are less well studied. We investigated convergence in minimum leaf water potential (Ψmin), conductivity per sapwood area (ks), Huber value (Hv) and xylem embolism and photosynthesis in four habitats across two seasons (summer and winter) in the Sydney region in heathland, woodland (ridge-top), woodland (below-ridge) and mangrove. Seasonality strongly influenced all parameters in all habitats. Winter Ψmin values were lower than those for summer in the heathland and both woodland habitats but summer Ψmin values were lower than those for winter in the mangrove. Summer ks values were higher than winter values in all habitats, while Hv was higher in winter than summer for all habitats. Loss of conductance due to xylem embolism was larger in summer than winter in eight of 11 species. We also investigated relationships between the hydraulic parameters across habitats. There was a strong, significant inverse correlation between log-transformed Hv and log-transformed ks, which held across the seasons. There were significant inverse correlations between Ψmin and xylem embolism, which held within seasons but not across seasons. We found a strong, significant positive correlation between ks and Ψmin also within seasons but not across seasons and a significant negative correlation between xylem embolism and ks for winter but only a weak negative correlation between xylem embolism and ks for summer. We believe the seasonal patterns and relationships in hydraulic architecture and water relations are driven by the cost of efficient sapwood. This is demonstrated by the negative correlation between photosynthetic rate and ks in winter.

scholarly journals Hydraulic architecture and water relations of several species at diverse sites around Sydney

2004 ◽  
Vol 52 (4) ◽  
pp. 509 ◽  
Author(s):  
Kate McClenahan ◽  
Catriona Macinnis-Ng ◽  
Derek Eamus
Keyword(s):  
Water Relations ◽  
Root Biomass ◽  
Woody Species ◽  
Leaf Water ◽  
Hydraulic Architecture ◽  
Evaporative Demand ◽  
Sapwood Area ◽  
Huber Value ◽  
Percentage Loss ◽  
Transverse Area

Seasonal comparisons of leaf water potential, root biomass, hydraulic architecture, xylem embolism and xylem dimensions were made for eight woody species in four diverse habitats (mangroves, coastal heathland, ridge-top woodland and river-flat woodland). In most comparisons, pre-dawn and minimum leaf water potentials were lower in winter than in summer, a result attributed to lower rainfall and a smaller root biomass in winter than in summer. Branch hydraulic conductivities (per unit transverse area, sapwood area or leaf area) were generally larger in summer than in winter across all species in all habitats. An inverse relationship between Huber value and conductivity was observed across all four habitats. Increased solar radiation and evaporative demand in the summer was associated with an increased percentage loss of xylem conductance arising from embolism, compared with winter. These results are discussed in the context of patterns and relationships among water relations, microclimate and hydraulic architecture.

The hydraulic architecture of Eucalyptus trees growing across a gradient of depth-to-groundwater

2015 ◽  
Vol 42 (9) ◽  
pp. 888 ◽  
Author(s):  
Sepideh Zolfaghar ◽  
Randol Villalobos-Vega ◽  
Melanie Zeppel ◽  
Derek Eamus
Keyword(s):  
Hydraulic Conductivity ◽  
Leaf Area ◽  
Water Availability ◽  
Safety Margin ◽  
Hydraulic Architecture ◽  
Sapwood Area ◽  
Huber Value ◽  
Xylem Vulnerability ◽  
Safety Margins ◽  
Hydraulic Safety

Heterogeneity in water availability acts as an important driver of variation in plant structure and function. Changes in hydraulic architecture represent a key mechanism by which adaptation to changes in water availability can be expressed in plants. The aim of this study was to investigate whether differences in depth-to-groundwater influence the hydraulic architecture of Eucalyptus trees in remnant woodlands within mesic environments. Hydraulic architecture of trees was examined in winter and summer by measuring the following traits: Huber value (HV: the ratio between sapwood area and leaf area), branch hydraulic conductivity (leaf and sapwood area specific), sapwood density, xylem vulnerability (P50 and Pe) and hydraulic safety margins across four sites where depth-to-groundwater ranged from 2.4 to 37.5 m. Huber value increased significantly as depth-to-groundwater increased. Neither sapwood density nor branch hydraulic conductivity (sapwood and leaf area specific) varied significantly across sites. Xylem vulnerability to embolism (represented by P50 and Pe) in both seasons was significantly and negatively correlated with depth-to-groundwater. Hydraulic safety margins increased with increasing depth-to-groundwater and therefore trees growing at sites with deeper water tables were less sensitive to drought induced embolism. These results showed plasticity in some, but not all, hydraulic traits (as reflected in HV, P50, Pe and hydraulic safety margin) in response to increase in depth-to-groundwater in a mesic environment.

Short Article: Analysing the relationship between target-to-target and distractor-to-target repetitions: Evidence for a common mechanism

2008 ◽  
Vol 61 (11) ◽  
pp. 1641-1649 ◽  
Author(s):  
Christian Frings
Keyword(s):  
Negative Correlation ◽  
Significant Negative Correlation ◽  
Common Mechanism ◽  
Short Article ◽  
Retrieval Mechanism ◽  
Target Repetition ◽  
Selection Tasks ◽  
The Cost ◽  
The Relationship ◽  
Cost Effect

In the present study an assumption of retrieval theories of negative priming was tested. In particular, retrieval theories assume that the same underlying process causes benefits in target-to-target repetition trials and cost effects in distractor-to-target repetition trials in selection tasks in which targets are accompanied by distractor stimuli. More specifically, retrieval theories predict a negative correlation: The higher the benefit in target-to-target repetition trials is, the higher the cost effect in distractor-to-target repetition trials should be. In fact, in a study with considerable power ( N = 110) and a design that allowed a confound-free detection of correlations, I observed a significant negative correlation between benefit and cost effects. This result is interpreted as evidence for a common retrieval mechanism.

Corticotrophin stimulation test: inverse correlation between basal serum cortisol and its response to corticotrophin

1981 ◽  
Vol 97 (4) ◽  
pp. 522-524 ◽  
Author(s):  
Subhash C. Kukreja ◽  
Gerald A. Williams
Keyword(s):  
Adrenal Gland ◽  
Negative Correlation ◽  
Inverse Correlation ◽  
Serum Cortisol ◽  
Normal Subjects ◽  
Significant Negative Correlation ◽  
Serum Cortisol Level ◽  
Cortisol Response ◽  
Basal Serum ◽  
Peak Value

Abstract. Serum cortisol response to synthetic corticotrophin (B1-24-ACTH) was evaluated in 21 normal subjects. There was significant negative correlation (r = −0.633, P < 0.001) between the basal serum cortisol and the increase in serum cortisol level in response to ACTH. Two subjects had an increase in serum cortisol of less than 194 nm/l (7.0 μg/100 ml) and two additional subjects had an increase of less than 278 nm/l (10.0 μg/100 ml). All subjects had an absolute peak value greater than 583 nm/l (21.0 μg/100 ml) at 30 or 60 min post-ACTH. Inverse correlation between basal serum cortisol and the increase in serum cortisol suggests that in patients who have high basal serum cortisol levels, endogenous ACTH may already have reduced the cortisol reserve of the adrenal gland.

scholarly journals Correlation of uric acid, urea, ammonia and creatinine of seminal plasma with semen parameters and fertilization rate of infertile couples

2017 ◽  
Vol 5 (2) ◽  
pp. 76-80 ◽  
Author(s):  
Sara Allahkarami ◽  
Mojgan Atabakhsh ◽  
Mohammad Nabi Moradi ◽  
Hadi Ghasemi ◽  
Maryam Bahmanzadeh ◽  
...  
Keyword(s):  
Uric Acid ◽  
Seminal Plasma ◽  
Negative Correlation ◽  
Negative Impact ◽  
Sperm Count ◽  
Inverse Correlation ◽  
Significant Negative Correlation ◽  
Fertilization Rate ◽  
Semen Parameters ◽  
Nitrogenous Compounds

Background: Ammonia, urea, uric acid, and creatinine are the major non-protein nitrogenous compounds (NPNs). It is reported that the concentration of NPNs in the seminal plasma of normal and infertile individuals is different and sperm is affected by NPNs. Objectives: The aim of this study was to determine the quantities of ammonia, urea, uric acid, and creatinine in seminal plasma and the correlation of these compounds with the fertilization rate after an intracytoplasmic sperm injection (ICSI). Methods: The levels of ammonia, urea, uric acid, and creatinine were determined in seminal plasma collected from 50 men. The ammonia and urea were determined by L-glutamate dehydrogenase and diacetyl monoxime method, respectively. Uric acid and creatinine were detected by enzymatic method and Jaffe reaction, respectively. The fertilization was evaluated around 16–18 hours post-ICSI on the appearance of 2 pronuclei and 2 polar bodies. The fertilization rate was calculated by the number of fertilized oocytes per the number of oocytes injected. Results: There was a significant negative correlation between seminal ammonia and sperm motility (P<0.05). Urea and creatinine had a negative correlation with respect to the sperm count (P<0.05). In addition, there was an inverse correlation between urea and uric acid of seminal plasma and sperm morphology (P<0.05). A significant negative correlation was found between seminal uric acid and urea with respect to the percentage of the fertilization rate (P<0.05). Conclusions: The findings of the present study showed that urea and uric acid in seminal plasma have a negative impact on the fertilization rate.

Thrombin generation in paediatric patients with congenital heart disease

2008 ◽  
Vol 28 (S 01) ◽  
pp. S61-S66 ◽  
Author(s):  
G. Cvirn ◽  
A. Rosenkranz ◽  
B. Leschnik ◽  
W. Raith ◽  
W. Muntean ◽  
...  
Keyword(s):  
Congenital Heart Disease ◽  
Heart Disease ◽  
Negative Correlation ◽  
Congenital Heart ◽  
Thrombin Generation ◽  
Significant Negative Correlation ◽  
Peak Height ◽  
Global Test ◽  
Paediatric Patients ◽  
Age Range

SummaryThrombin generation was studied in paediatric patients with congenital heart disease (CHD) undergoing cardiac surgery using the calibrated automated thrombography (CAT) in terms of the lag time until the onset of thrombin formation, time to thrombin peak maximum (TTP), endogenous thrombin potential (ETP), and thrombin peak height. The suitability to determine the coagulation status of these patients was investigated. Patients, material, methods: CAT data of 40 patients with CHD (age range from newborn to 18 years) were compared to data using standard coagulation parameters such as prothrombin (FII), antithrombin (AT), tissue factor pathway inhibitor (TFPI), prothrombin fragment 1.2 (F 1.2), thrombin-antithrombin (TAT), activated partial thromboplastin time (aPTT), and prothrombin time (PT). Results: A significant positive correlation was seen between ETP and FII (p < 0.01; r = 0.369), as well as between peak height and F II (p < 0.01; r = 0.483). A significant negative correlation was seen between ETP and TFPI values (p < 0.05; r = –0.225) while no significant correlation was seen between peak height and TFPI. A significant negative correlation was seen between F 1.2 generation and ETP (p < 0.05; r = –0.254) and between F 1.2 generation and peak height (p < 0.05; r = –0.236). No correlation was seen between AT and ETP or peak. Conclusions: CAT is a good global test reflecting procoagulatory and inhibitory factors of the haemostatic system in paediatric patients with CHD.

Negative Correlation Between Serum Levels of Homocysteine and Apolipoprotein M

2019 ◽  
Vol 19 (2) ◽  
pp. 120-126
Author(s):  
J. Wei ◽  
Y. Yu ◽  
Y. Feng ◽  
J. Zhang ◽  
Q. Jiang ◽  
...  
Keyword(s):  
Negative Correlation ◽  
Hepg2 Cells ◽  
Serum Levels ◽  
Significant Negative Correlation ◽  
Mrna Levels ◽  
Rt Pcr ◽  
Apolipoprotein M ◽  
Protein Mass ◽  
Protein Levels ◽  
Phosphoinositide 3 Kinase

Background: Homocysteine (Hcy) has been suggested as an independent risk factor for atherosclerosis. Apolipoprotein M (apoM) is a constituent of the HDL particles. The goal of this study was to examine the serum levels of homocysteine and apoM and to determine whether homocysteine influences apoM synthesis. Methods: Serum levels of apoM and Hcy in 17 hyperhomocysteinemia (HHcy) patients and 19 controls were measured and their correlations were analyzed. Different concentrations of homocysteine (Hcy) and LY294002, a specific phosphoinositide 3- kinase (PI3K) inhibitor, were used to treat HepG2 cells. The mRNA levels were determined by RT-PCR and the apoM protein mass was measured by western blot. Results: We found that decreased serum apoM levels corresponded with serum HDL levels in HHcy patients, while the serum apoM levels showed a statistically significant negative correlation with the serum Hcy levels. Moreover, apoM mRNA and protein levels were significantly decreased after the administration of Hcy in HepG2 cells, and this effect could be abolished by addition of LY294002. Conclusions: resent study demonstrates that Hcy downregulates the expression of apoM by mechanisms involving the PI3K signal pathway.

scholarly journals Daytime nap and nighttime breastfeeding are associated with toddlers’ nighttime sleep

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Machiko Nakagawa ◽  
Hidenobu Ohta ◽  
Rinshu Shimabukuro ◽  
Yoko Asaka ◽  
Takayo Nakazawa ◽  
...  
Keyword(s):  
Sleep Duration ◽  
Negative Correlation ◽  
Significant Negative Correlation ◽  
Sleep Diary ◽  
Daytime Nap ◽  
Nighttime Sleep

AbstractThe purpose of the present study is to examine the association between toddlers' sleep arrangements and their nighttime sleep duration and other sleep variables. For this investigation, we performed a study in which child activity and sleep levels were recorded using actigraphy. The parents of 1.5-year-old toddlers (n = 106) were asked to attach an actigraphy unit to their child’s waist with an adjustable elastic belt and complete a sleep diary for 7 consecutive days. Questionnaires were used to assess the sleep arrangements of the toddlers. There was a significant negative correlation between nap duration and nighttime sleep duration, suggesting that longer nap sleep induces shorter nighttime sleep duration. Among the sleep arrangements, such as nighttime breastfeeding or co-sleeping, only nighttime breastfeeding predicted shorter nighttime sleep duration. Our findings indicate that shorter naps induce a longer nighttime sleep in 1.5-year-old toddlers while nighttime breastfeeding decreases their nighttime sleep duration.

scholarly journals Cost per DALY averted in low, middle- and high-income countries: evidence from the global burden of disease study to estimate the cost-effectiveness thresholds

2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Rajabali Daroudi ◽  
Ali Akbari Sari ◽  
Azin Nahvijou ◽  
Ahmad Faramarzi
Keyword(s):  
Cost Effectiveness ◽  
Inverse Correlation ◽  
Gdp Per Capita ◽  
Middle Income ◽  
Capita Health Expenditure ◽  
Per Capita ◽  
Healthcare Interventions ◽  
Disease Study ◽  
The Cost ◽  
Very High

Abstract Background Determining the cost-effectiveness thresholds for healthcare interventions has been a severe challenge for policymakers, especially in low- and middle-income countries. This study aimed to estimate the cost per disability-adjusted life-year (DALY) averted for countries with different levels of Human Development Index (HDI) and Gross Domestic Product (GDP). Methods The data about DALYs, per capita health expenditure (HE), HDI, and GDP per capita were extracted for 176 countries during the years 2000 to 2016. Then we examined the trends on these variables. Panel regression analysis was performed to explore the correlation between DALY and HE per capita. The results of the regression models were used to calculate the cost per DALY averted for each country. Results Age-standardized rate (ASR) DALY (DALY per 100,000 population) had a nonlinear inverse correlation with HE per capita and a linear inverse correlation with HDI. One percent increase in HE per capita was associated with an average of 0.28, 0.24, 0.18, and 0.27% decrease on the ASR DALY in low HDI, medium HDI, high HDI, and very high HDI countries, respectively. The estimated cost per DALY averted was $998, $6522, $23,782, and $69,499 in low HDI, medium HDI, high HDI, and very high HDI countries. On average, the cost per DALY averted was 0.34 times the GDP per capita in low HDI countries. While in medium HDI, high HDI, and very high HDI countries, it was 0.67, 1.22, and 1.46 times the GDP per capita, respectively. Conclusions This study suggests that the cost-effectiveness thresholds might be less than a GDP per capita in low and medium HDI countries and between one and two GDP per capita in high and very high HDI countries.

scholarly journals Morphological and physiological plasticity response to low nitrogen stress in black cottonwood (Populus deltoides Marsh.)

2021 ◽  
Author(s):  
Cun Chen ◽  
Yanguang Chu ◽  
Qinjun Huang ◽  
Changjun Ding ◽  
Weixi Zhang ◽  
...  
Keyword(s):  
Negative Correlation ◽  
Nitrogen Use Efficiency ◽  
Root Biomass ◽  
Populus Deltoides ◽  
Leaf Traits ◽  
Nitrogen Level ◽  
Nitrogen Use ◽  
Use Efficiency ◽  
Normal Nitrogen ◽  
Low Nitrogen

AbstractIt is important to evaluate nitrogen use efficiency and nitrogen tolerance of trees in order to improve their productivity. In this study, both were evaluated for 338 Populus deltoides genotypes from six provenances. The plants were cultured under normal nitrogen (750 μM NH4NO3) and low nitrogen (5 μM NH4NO3) conditions for 3 months. Growth, chlorophyll content and glutamine synthetase activity of each genotype were measured. Under low nitrogen, heights, ground diameter, leaf area, leaf and root biomass, and chlorophyll contents were significantly lower than those under normal nitrogen level. Correlation analysis showed that nutrient distribution changed under different nitrogen treatments. There was a negative correlation between leaf traits and root biomass under normal nitrogen level, however, the correlation became positive in low nitrogen treatment. Moreover, with the decrease of nitrogen level, the negative correlation between leaf morphology and chlorophyll levels became weakened. The growth of the genotypes under the two treatments was evaluated by combining principal component analysis with a fuzzy mathematical membership function; the results showed that leaf traits accounted for a large proportion of the variation in the evaluation model. According to the results of comprehensive evaluation of plants under the two treatments, the 338 P. deltoides genotypes could be divided into nine categories, with wide genotypic diversity in nitrogen use efficiency and low nitrogen tolerance. As a result, 26 N-efficient genotypes and 24 N-inefficient genotypes were selected. By comparative analysis of their morphological and physiological traits under the two treatments, leaf traits could be significant indicators for nitrogen use efficiency and nitrogen tolerance, which is of considerable significance for breeding poplar varieties with high nitrogen use efficiencies.

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