Biodiversity of the African savanna woodlands: how does it change with land use?

The savanna woodlands of Southern Africa, colloquially termed the miombo, are poorly described in terms of biodiversity compared to other biomes. They have therefore been underrepresented in the wider understanding of how land use intensification is shaping global biodiversity. Land use change is known to reduce biodiversity and disrupt intactness of ecological communities with consequences for ecosystem functioning, resilience, and services. Miombo woodlands are described as biodiversity hotspots due to a high endemism of species and the presence of megafauna. At the same time, they are also considered dynamic socio-ecological systems shaped by disturbances and the land use activities of people. The patterns of biodiversity change in these tropical ecosystems may, therefore, have their own unique contexts, understanding of which will be essential for biodiversity and land use management in these ecosystems. In this thesis, I identified the patterns of biodiversity change in response to the two major land use practices in the two dominant woodland types in southern African woodlands: the selective logging due to charcoal production in the mopane woodlands, and agricultural expansion in the miombo. I also examined the impact of two main disturbance agents, humans and elephants, on habitat structure and biodiversity in mopane woodlands. Across all chapters in this thesis, I investigated the effects of land use change and habitat modification on biodiversity empirically using chronosequences. To understand biodiversity change, I employed a hierarchical multilevel modelling approach making inferences at the three levels of ecological communities: species, community, and meta-community (set of ecological communities at different sites). I selected six villages in the charcoal production hotspot of southern Mozambique and carried out field surveys for three taxonomic groups: trees, mammals and ground beetles. I modelled the counts of trees and beetles and incidence of mammals using meta-community occurrence models in a Bayesian framework with the intensity class of the villages, above-ground biomass and land cover type as predictors. The results suggested that the species richness of trees and mammals declined by 12 and 8.5 % respectively while that of beetles increased by 3.5%, albeit non-significantly. In addition, the beta diversity of trees decreased while that of mammals increased. The results show that while both trees and mammals reduced in richness, they responded differently to charcoal production in terms of community organisation. The trees underwent subtractive homogenisation (decrease in alpha and beta diversities) primarily because of deterministic processes induced by selective harvesting of tree stems for charcoal. Mammal communities, on the other hand, showed subtractive heterogenization (decrease in alpha, but increase in beta diversity) mainly due to random extinctions. In the agriculture frontier of miombo-dominated northern Mozambique, I investigated the effects of fragmentation and habitat loss caused by agricultural expansion on diversity and composition of trees and mammals. I modelled the occurrences of trees and mammals using occupancy models with the fragmentation and quantity of woodland cover as predictors. The model showed that most tree species (n=10), mainly the timber and firewood species, linearly declined in population size as fragmentation increased. Mammals, on the other hand, showed a nonlinear response. Seven mammal species increased at the lower levels of fragmentation. However, at the higher levels, none of the mammal species increased while two declined. Similarly, the species richness of trees linearly declined, while that of mammals increased up to a fragmentation level of 55-65% and declined above this limit. The beta diversity of trees increased with fragmentation while that of mammals decreased. The results suggest that, although fragmentation reduces species richness of both trees and mammals, it affects their species compositions in different ways. Trees undergo subtractive heterogenization due to random species losses while mammals experience subtractive homogenisation mainly due to the combined effects of fragmentation-led habitat loss and intensified hunting. Finally, this study concludes that, above 75% fragmentation or below 26% habitat quantity, both taxonomic groups endure biodiversity loss. The threshold results here corroborate similar habitat quantity thresholds (20-30%) observed elsewhere in different ecosystems. However, they differ with the widespread notion that above 30% habitat quantity, the effect of fragmentation is non-existent. The results here emphasize that taxonomic groups respond differently, the diversity and population size of mammals reduced only after the habitat threshold, whereas, those of trees showed linear decrease with fragmentation most likely due to fragmentation-led habitat loss. Lastly, I examined the effects of disturbance by humans and elephants on habitat structure and bird diversity by conducting a space for time substitution comparison in the mopane woodlands of Zambia. To examine the woodland structure, I modelled the structural attributes of habitat (stem diameter, stand density, and basal area) using mixed models with the proportion of affected stems by humans and elephants as explanatory variables. I found that elephant disturbance was associated with higher stem diameters, low stand densities, but no change in basal area. Human disturbance, on the other hand, was related to reductions in stand density and basal area, but no change in the stem diameter. Further, I tested species and functional diversity of birds against the covariates of habitat structure and disturbance. I found that bird communities reduced in species richness in both, human as well as elephant disturbed areas. However, the functional diversity did not change with elephant disturbance. I concluded that human disturbance reduces woody biomass (basal area is correlated with woody biomass) of mopane woodlands and functional diversity of birds whilst elephants do not. In this thesis, I conclude that human driven land use change in the miombo woodlands erodes alpha diversity of all taxonomic groups. However, increases in beta diversity of mammals with charcoal land use and trees in agricultural land use may maintain their diversities at the meta-community level

The Botany, Chemistry, Pharmacological and Therapeutic Application of Oxalis Corniculata Linn– A Review

Oxalis corniculata Linn. is an endangered and medicinally important plant indigenous to tropical and subtropical regions of the world. Its medicinal usage is reported in Indian pharmaceutical codex, the Chinese, British and the American pharmacopoeias and in different traditional system of medicines such as Ayurveda, Unani and Siddha. The review reveals that wide ranges of phytochemical constituents have been isolated from the plant like flavanoids, tannins, phytosterols, phenol, glycoseides, fatty acids, galacto-glycerolipid and volatile oil. The leaves contain flavonoids, iso vitexine and vitexine-2”- O- beta – D- glucopyrunoside. It is rich source of essential fatty acids like palmitic acid, oleic, linoleic, linolenic and stearic acids and it possesses important activities like Antioxidant, Anticancer, anthelmintic, Anti-inflammatory, Analgesic, Steroidogenic, Antimicrobial, Antiamoebic, Antifungal, Astringent, Depurative, Diuretic, Emmenagogue, Febrifuge, Cardio relaxan, stomachic and Styptic have also been reported. These repots are very encouraging and indicate that herb should be studied more expensively for its therapeutic benefits. This article briefly reviews the botany, pharmacology, biochemistry and therapeutic application of the plant. This is an attempt to compile and document information on different aspects of Oxalis corniculata and highlight the need for research and development. Keywords: Oxalis corniculata, Galacto-glycerolipid, Pharmacological activities, Antioxidant, Anticancer

Modified chitosan hydrogels as drug delivery and tissue engineering systems: present status and applications

AbstractChitosan, a natural cationic polysaccharide, is prepared industrially by the hydrolysis of the aminoacetyl groups of chitin, a naturally available marine polymer. Chitosan is a non-toxic, biocompatible and biodegradable polymer and has attracted considerable interest in a wide range of biomedical and pharmaceutical applications including drug delivery, cosmetics, and tissue engineering. The primary hydroxyl and amine groups located on the backbone of chitosan are responsible for the reactivity of the polymer and also act as sites for chemical modification. However, chitosan has certain limitations for use in controlled drug delivery and tissue engineering. These limitations can be overcome by chemical modification. Thus, modified chitosan hydrogels have gained importance in current research on drug delivery and tissue engineering systems. This paper reviews the general properties of chitosan, various methods of modification, and applications of modified chitosan hydrogels

Agricultural expansion in African savannas: effects on diversity and composition of trees and mammals

AbstractLand use change (LUC) is the leading cause of biodiversity loss worldwide. However, the global understanding of LUC's impact on biodiversity is mainly based on comparisons of land use endpoints (habitat vs non-habitat) in forest ecosystems. Hence, it may not generalise to savannas, which are ecologically distinct from forests, as they are inherently patchy, and disturbance adapted. Endpoint comparisons also cannot inform the management of intermediate mosaic landscapes. We aim to address these gaps by investigating species- and community-level responses of mammals and trees along a gradient of small scale agricultural expansion in the miombo woodlands of northern Mozambique. Thus, the case study represents the most common pathway of LUC and biodiversity change in the world's largest savanna. Tree abundance, mammal occupancy, and tree- and mammal-species richness showed a non-linear relationship with agricultural expansion (characterised by the Land Division Index, LDI). These occurrence and diversity metrics increased at intermediate LDI (0.3 to 0.7), started decreasing beyond LDI &gt; 0.7, and underwent high levels of decline at extreme levels of agricultural expansion (LDI &gt; 0.9). Despite similarities in species richness responses, the two taxonomic groups showed contrasting β-diversity patterns in response to increasing LDI: increased dissimilarity among tree communities (heterogenisation) and high similarity among mammals (homogenisation). Our analysis along a gradient of landscape-scale land use intensification allows a novel understanding of the impacts of different levels of land conversion, which can help guide land use and restoration policy. Biodiversity loss in this miombo landscape was lower than would be inferred from existing global syntheses of biodiversity-land use relations for Africa or the tropics, probably because such syntheses take a fully converted landscape as the endpoint. As, currently, most African savanna landscapes are a mosaic of savanna habitats and small scale agriculture, biodiversity loss is probably lower than in current global estimates, albeit with a trend towards further conversion. However, at extreme levels of land use change (LDI &gt; 0.9 or &lt; 15% habitat cover) miombo biodiversity appears to be more sensitive to LUC than inferred from the meta-analyses. To mitigate the worst effects of land use on biodiversity, our results suggest that miombo landscapes should retain &gt; 25% habitat cover and avoid LDI &gt; 0.75—after which species richness of both groups begin to decline. Our findings indicate that tree diversity may be easier to restore from natural restoration than mammal diversity, which became spatially homogeneous.</jats:p

Investigation of all-optical inverter system with NRZ and RZ modulation formats at 100 Gbit/s

U radu se predstavlja komparativno istraživanje formata modulacije ne-vraćanje-na-nulu (non-return-to-zero) i vraćanje-na-nulu (return-to-zero) za ulazu optičkog pretvarača kod 100 Gbit/s. Uspoređuju se različite performanse kao što su dijagram oka, omjer gašenja i učestalost pogrešnih bitova kod različite učestalosti bitova na osnovu prikladnosti formata podataka. To pokazuje da su impulsi vraćanja na nulu promijenjeni po sličnom uzorku te je stoga učestalost pogrešnih bitova bolja od formata non-return-to-zero. Na format non-return-to-zero više djeluje nelinearnost optičkog pojačala poluvodiča te je stoga degradirana učestalost pogrešnih bitova, a poboljšan omjer gašenja (ekstinkcije).The paper presents the comparative investigation on non-return-to-zero and return-to-zero modulation formats for optical inverter gate at 100 Gbit/s. Various performances as eye pattern, extinction ratio and bit error rate at different bit-rate are compared based on suitability of data formats. It indicates that return-to-zero pulses are distorted in a similar pattern, therefore bit error rate is better than non-return-to-zero format. The non-return-to-zero is more affected by non-linearity of semiconductor optical amplifier hence the bit error rate is degraded and extinction ratio is improved

Determinants of Intravascular Resistance in Indian Diabetic Nephropathy Patients: A Hospital-Based Study

Aims and Objectives. Metabolic dysregulation has failed to explain clinical variability of patients with diabetic nephropathy and hence a renewed interest emerged in haemodynamic factors as determinant of progression and development of diabetic nephropathy. We therefore studied for various factors which can correlate with raised renal vascular resistance in diabetic nephropathy. Material and Methods. Renal vascular resistance was measured in patients with established and incipient diabetic nephropathy and compared with controls using noninvasive color Doppler examinations of intrarenal vasculature. Results. Renal vascular resistance correlated with age, duration of disease, GFR, serum creatinine, and stage of retinopathy. Renal vascular resistance was significantly reduced in patients on treatment with RAAS inhibitors and insulin, than those on OHA and antihypertensives other than RAAS inhibitors. Conclusion. The study implies that renal vascular resistance may help identify diabetics at high risk of developing nephropathy, and these set of patients could be candidates for RAAS inhibition and early insulin therapy even in patients without albuminuria

In vitro evaluation of Transdermal Patch of Palonosetron for Antiemetic Therapy

Skin is one of the routes for systemic delivery of drugs through various drug delivery system. A transdermal Drug Delivery System (TDDS) is one of the most reliable and useful system to deliver drug systemically through skin. Generally medicated patch is placed on skin for delivery of medication through it into the blood stream. The aim of present study was to formulate and evaluate Palonosetron transdermal patch in vitro that could be used for antiemetic therapy. The incorporation ofPalonosetron a serotonin 5-HT3 antagonist drug was envisaged. The TDDS was prepared by solvent evaporation technique and was evaluated for organoleptic characteristics and other physicochemical properties Thickness, Weight variation, Drug content uniformity, Tensile strength, % Elongation, Folding endurance &amp; Moisture content. The in vitro permeation study of the patch was carried out through KesaryChein diffusion cell as barrier membrane. Phosphate buffer pH 7.4 was used as dissolution medium and the temperature was maintained at 37 ± 10C. The in vitro permeation study of the prepared patch indicated a time dependent increase in drug release throughout the study. The percentage of cumulative drug release was found to be 76.25% in 24 hours.The study shows a new approach to work in with Palonosetron