302 research outputs found
Clonal integration in Ochthochloa compressa under extreme environmental conditions
While multiple studies have indicated the benefit of clonal integration and its role in resisting harsh environmental conditions, many researchers have indicated the need for further studies to understand fully the role of clonal integration and what determines the optimal strategies in various environments. In this project a series of studies were carried out in an extremely arid area (Al Thumam area in the Arabian Peninsula) to contribute to the knowledge of the benefits of clonal integration and understanding the behaviour of the clonal grass Ochthochloa compressa. This study is unique because it has investigated the benefits of clonality in one of the harshest environments where clonal plants are found.
Experiment 1. I aimed to understand the patterns of spread and expansion of stolons, particularly whether stolons grew in random directions or are directed to better patches by the mother ramets to establish new daughter ramets maximizing their chances of success. I measured nutrient contents (N, P and K) in patches where mother plants grew, and where daughter ramets had established. In addition, I sampled nearby unoccupied patches. Mother plants were found in patches with higher N concentrations than where the daughter ramets were found. There were no differences in concentration of P; while K was the lowest where not fully rooted daughters were found. The results suggest that daughter ramets did not establish in the best areas, indicating that the spread and expansion of stolons in the O. compressa occurs randomly.
Experiment 2. I investigated the effects of the addition of fertilizer to mother and daughter ramets, including addition of nutrients to daughters disconnected from the mother ramets. Cutting the stolons caused to death of the daughter because these ramets were still dependent on the mother ramets. When connected, mothers that received nutrients affected some transference nutrients to daughter ramets. In contrast, the daughters accumulated the nutrients in above ground tissue when receiving added fertilizer, and there was no sign of transference to the mother ramet. Nutrient addition did not affect in any case the efficiency photosynthetic in both mother and daughter ramets.
Experiment 3. In this experiment, I focused on the effect of the distance between mother and daughter ramets on the performance of daughter ramets. Daughters located close to the mother ramets could suffer competition by the mother if they are within the area of the root system. The results showed no significant differences between mother and daughter ramets in the concentration of nitrogen, phosphorus, and potassium nor in photosynthetic activity. This indicates that the daughters have the ability to resist competition through continued support from their mothers despite the scarcity of resources and the harsh environmental conditions in the study area.
Experiment 4. In this experiment, I studied the effect of simulated grazing on both mother and daughter ramets when one of them was clipped and 50-60% of the leaves were removed, while remaining connected. Clipping did not affect the N content of mother ramets, but the concentration of phosphorus was decreased by clipping. K was lower in mother ramets connected to clipped daughters. Daughters connected to clipped mothers had higher N concentration but K and P did not change. Clipping of daughters did not have any effect on mother ramets concentration of nutrients. Photosynthetic efficiency did not record any significant differences when ramets were clipped. The results indicate that O. compressa strategy to resist grazing consists mainly in continuing to support daughter ramets.
As far as I know, this is the first study of the phenomenon of clonal integration for O. compressa. This study revealed the importance of clonal integration for O. compressa to resistance of the harsh environmental conditions. Under the harsh conditions these plants live, the preferred strategy seems to be for the mother ramets to expand by producing ramets in random sites and heavily subsidize their growth with nutrient, and almost certainly water. Indeed, I documented strong evidence of transfer of nutrients through the stolons from mother ramets to daughter ramets but no evidence of transfer in the other direction even when nutrients were supplied to daughters. Further, seemingly surplus N available to the mother when clipping limited their foliar tissues was directed to daughters rather than to re-sprouting (which was probably limited by water availability).
The insights obtained on the biology of O. compressa are critical as it is a native plant in a harsh environment, and it is suitable for fodder for pastoral animals, as well as having potential for restoration of degraded areas. Further, it provides new insights into the phenomenon of clonal integration in harsh habitats, and area which still needs further study and research.Thesis (Ph.D.) -- University of Adelaide, School of Biological Sciences, 201
Parasite Detection Model for Neglected Tropical Disease Diagnosis
Kato-katz is the most commonly used microscopy-based technique in the diagnosis of Neglected Tropical Diseases (NTDs). This paper describes the preliminary studies that are involved in the automated detection of parasitic eggs in a given Kato-katz image. The studies involve application of pattern recognition techniques based on template matching to detect the presence of parasites in the images of kato-katz slides. The results from this study indicate that using a combination of image segmentation and pattern recognition algorithms generates better results as they deal with the complex nature of the images, such as their spurious intensity patterns and shapes.
Clinical Relevanceâ This paper describes interdisciplinary work that applies image processing algorithms to kato-katz images to solve clinical parasitology problems
Design modern structure for heterojunction quantum dot solar cells
This paper proposal new structure for improving the optical, electrical characteristics and efficiency of 3rd generation heterojunction quantum dot solar cell (HJQDSC) (ITO/CdS/QDPbS/Au) model by using the quantum dot window layer instead of bulk structure layers cell. Also, this paper presents theoretically analysis for the performance of the proposal HJQDSC (ITO/QDCdS/QDPbS/Au) structure. The new design structure was applied on traditional (SnO2/CdS/CdTe/Cu) and (ZnO/CdS/CIGS/Mo) thin film solar cells which based on sub-micro absorber layer thickness models by replacing the bulk CdTe, CIGS absorber layers and CdS window layer with quantum dot size materials to achieve higher efficiency with lesser usage layer material. Also, it has been studied the effect of using semiconductors layers in quantum dots size on electric and optical properties of thin film solar cells and the effect of window and absorber layers quantum dots radii on the performance of solar cells. Finally, a thermal efficiency analysis has been investigated for explaining the importance of new structure HJQD solar cells
MICROBICIDAL AND CYTOTOXIC ACTIONS OF METHANOLIC CRUDE EXTRACTS OF A. MULTIFLORA.-ROXB
Objective: The study presented here was carried out for the evaluation of microbicidal and cytotoxic potential of methanolic extract of leaves of Ammannia multiflora. The microbicidal activity was tested against 16 bacteria. The cytotoxic activity was tested against brine shrimp species Artemia salina.
Methods: The microbicidal effect of the plant extracts was tested in vitro by the disc diffusion method with 16 standard bacterial strains. Artemia salina; a brine shrimp species; was used to assess cytotoxic activity.
Results: Among the subjected 16 different bacteria; in case of S. boydii; the zone of inhibition was higher (22.0 mm) at 500 Ôg/ml concentration. Whereas in the case of E. foecalis, the zone of inhibition was higher (8.0 mm) at 250 Ôg/ml concentration. In S. pyogenes; zone of inhibition was higher at 500 Ôg/ml concentration (13.0 mm). The growth of S. saprophyticus (9 mm), S. agalactiae (7 mm) and S. sonnei (7 mm) was also moderately inhibited. The extract exhibited effectiveness against 7 different species of bacteria out of 16. Cytotoxic effect was determined in lethality bioassay of brine shrimp species Artemia salina. The plant extracts exhibited significant cytotoxic property which was reflected in LC50 and LC90values of 20.42Ôg/ml and 229.09 Ôg/ml respectively. Cytotoxic property was found as dose dependent manner.
Conclusion: These results suggest that, Ammania multiflora can effectively be used for its significant microbicidal action. It is also effective as cytotoxic agent and thus, could justify its use in traditional medicine
Dietary intake and biomarkers of alpha linolenic acid and risk of all cause, cardiovascular, and cancer mortality: systematic review and dose-response meta-analysis of cohort studies
OBJECTIVE: To examine the associations between dietary intake and tissue biomarkers of alpha linolenic acid (ALA) and risk of mortality from all causes, cardiovascular disease (CVD), and cancer. DESIGN: Systematic review and meta-analysis of prospective cohort studies. DATA SOURCES: PubMed, Scopus, ISI Web of Science, and Google Scholar to 30 April 2021. STUDY SELECTION: Prospective cohort studies that reported the risk estimates for death from all causes, CVD, and cancer. DATA SYNTHESIS: Summary relative risks and 95% confidence intervals were calculated for the highest versus lowest categories of ALA intake using random effects and fixed effects models. Linear and non-linear dose-response analyses were conducted to assess the dose-response associations between ALA intake and mortality. RESULTS: 41 articles from prospective cohort studies were included in this systematic review and meta-analysis, totalling 1â197â564 participants. During follow-up ranging from two to 32 years, 198â113 deaths from all causes, 62â773 from CVD, and 65â954 from cancer were recorded. High intake of ALA compared with low intake was significantly associated with a lower risk of deaths from all causes (pooled relative risk 0.90, 95% confidence interval 0.83 to 0.97, I2=77.8%, 15 studies), CVD (0.92, 0.86 to 0.99, I2=48.2%, n=16), and coronary heart disease (CHD) (0.89, 0.81 to 0.97, I2=5.6%, n=9), and a slightly higher risk of cancer mortality (1.06, 1.02 to 1.11, I2=3.8%, n=10). In the dose-response analysis, a 1 g/day increase in ALA intake (equivalent to one tablespoon of canola oil or 0.5 ounces of walnut) was associated with a 5% lower risk of all cause (0.95, 0.91 to 0.99, I2=76.2%, n=12) and CVD mortality (0.95, 0.91 to 0.98, I2=30.7%, n=14). The pooled relative risks for the highest compared with lowest tissue levels of ALA indicated a significant inverse association with all cause mortality (0.95, 0.90 to 0.99, I2=8.2%, n=26). Also, based on the dose-response analysis, each 1 standard deviation increment in blood concentrations of ALA was associated with a lower risk of CHD mortality (0.92, 0.86 to 0.98, I2=37.1%, n=14). CONCLUSIONS: The findings show that dietary ALA intake is associated with a reduced risk of mortality from all causes, CVD, and CHD, and a slightly higher risk of cancer mortality, whereas higher blood levels of ALA are associated with a reduced risk of all cause and CHD mortality only. SYSTEMATIC REVIEW REGISTRATION: PROSPERO CRD42021229487
The impact of CSR and green investment on stock return of Chinese export industry
A green and sustainable business environment has gained the
attention of recent researchers and policymakers due to environmental and social issues globally. Therefore, the present research
investigates the impact of corporate social responsibilities (CSR),
green investment, green credit, and assets return on the stock
return of the Chinese export industry. This study has taken the ten
top export companies from China using the database of the
Shanghai stock exchange. This study collected data from financial
statements and stock exchange databases from 2009 to 2020. This
study has used panel data analysis techniques such as robust standard error and fixed effect model (FEM) to examine the relations
among the variables. The results revealed that CSR, green investment, green credit, and return on assets have a significant and positive association with the stock return of selected industries. These
results imply that CSR instigates higher financial performance in the
export industry; thus, improving CSR and sustainable financing promote socio-economic and societal development
Teaching to transform surgical culture: an educational programme and thematic analysis in a general surgery department
Introduction General surgery departments are busy, meaning educational opportunities may be sporadic. Clinical priorities can sometimes supersede teaching and trainees may feel alienated at the periphery of the working community. In this study, we demonstrate how a reflective, multidisciplinary general surgery teaching programme was established and use this to assess the impact of structured teaching on surgical doctors of all grades in the department. Methods Twelve semi-structured telephone interviews were conducted with participants of varying grades. Transcripts were analysed using a grounded theory thematic analysis, revealing four themes: the value of teaching; learning as a community; barriers to successful training; and culture of surgery. Discussion Teaching helped juniors construct healthy narratives around general surgery and encouraged a process of professional identity formation. Pairing junior and senior colleagues allowed both to develop their skills, and reflective learning revealed new learning opportunities. Transparency across the âcommunity of practiceâ was achieved and the programme helped juniors overcome negative stereotypes of intimidation embedded in the hidden surgical curriculum. Conclusion Reflective, multidisciplinary learning can challenge the hidden curriculum and encourage team cohesion. A commitment to critical reflective teaching will be vital in cultivating surgeons of the future
Effect of DLC Coating on Tribological Behavior of Cylinder Liner-piston Ring Material Combination When Lubricated with Jatropha Oil
AbstractThe expansion of modern engines would have been unfeasible without advanced lubricant chemistry and proper lubricant formulation. Introduction of diamond like carbon (DLC) coatings opens further possibilities in improving performance of engine and transmission components, which cannot longer be achieved only by lubricant design.DLC coatings show extremely good promise for a number of applications in automotive components as they exhibit excellent tribological properties. In this paper, the tribological performance of hydrogenated amorphous carbon (a-C: H)DLC coating with Jatropha oil was evaluated using a four ball Tribometer also with commercial synthetic lubrication oil (SAE 40) used as base lubricant. Experimental results demonstrated that the hydrogenated amorphous carbon (a-C: H)DLC coating exhibited better performance with Jatropha oil in terms of wear and friction under similar operating conditions compared to the uncoated stainless. Thus, usage of hydrogenated amorphous carbon (a-C: H)DLC coating with Jatropha oil in the long run may have a positive impact on engine life
Comparative Effects of Different Feeds on Production and Reproduction of Crossbred Heifers in Gangachara Upazila, Rangpur, Bangladesh
The present study was conducted from January to June 2014, in Gangachara Upazila of Rangpur District, Bangladesh. A sample of 60 cross-bred dairy cows: Local Ă Holstein Friesian (LĂHF) = 30 and Local Ă Sahiwal (LĂSh) = 30 were selected for in depth study. The average age at first heat, services per conception, age at first calving, post-partum heat period, the average milk production, the average lactation period were observed after feeding three types of feed: type-I (Sweet jamboo grass), type-II (Jomjom Dairy feed) and type-III (Advance Chemical Industry) feeding system. Local Ă Holstein Friesian (LĂHF) cross and Local Ă Sahiwal (LĂSh) cross cows showed significantly (
Interference Mitigation Using Uplink Power Control in 5G Relay-Based Heterogeneous Networks
Heterogeneous network (HetNet) is an attractive solution for future cellular networks with high data rate and coverage requirements. In HetNets, small cells such as micro cells, pico cells, femto cells and relay node (RN) are added to the network of macro cells in the same region. A large number of low power RNs produces new cell edges with significant intra-cell and inter-cell interferences. In the uplink (UL) scenarios of time-division based HetNets with RN, the user equipment (UE) desired signal may be interfered by the transmissions of the co-channel UEs during the first time slot and by the transmissions of the co-channel UEs or RNs during the second time slot. The interference caused by the RNs may significantly degrade the UE signal. UL transmission power control (PC) is essential for mitigating interference and, as a result, enhancing the cell edge and overall system performance. This research proposes a PC algorithm in order to mitigate the UL interference in 5g relay-based HetNets. This research also investigates the UL performance of HetNets when PC is applied at the RNs. Simulation results indicate that UL PC at the RNs greatly reduces average interference and improves average UL signal-to-interference-plus-noise ratio (SINR) and average UL end-to-end throughput compared to the situation in which UL PC is not implemente
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