Analyse phytogéographique comparative des savanes et des forêts de Ngotto (République Centrafricaine)

After several investigations on the savanna and forest of Ngotto (Central African Republic), we propose a phytogeographical interpretation of our data on the systematic (level family), the biological forms, the dispersion of diaspores and phytogeographical elements spectra. These spectra are given regarding both formation type (savanna, forest) to appreciate their originality. Then, a comparaison is driven in order to set up the differences between these two formations.

Characterization of autonomous thyroid adenoma: metabolism, gene expression, and pathology.

Fifty-one in vivo characterized autonomous single adenomas have been studied for functional parameters in vitro, for gene and protein expression and for pathology, and have been systematically compared to the corresponding extratumoral quiescent tissue. The adenomas were characterized by a high level of iodide trapping that corresponds to a high level of Na+ /iodide symporter gene expression, a high thyroperoxidase mRNA and protein content, and a low H2O2 generation. This explains the iodide metabolism characteristics demonstrated before, ie, the main cause of the "hot" character of the adenomas is their increased iodide transport. The adenomas spontaneously secreted higher amounts of thyroid hormone than the quiescent tissue and in agreement with previous in vivo data, this secretion could be further enhanced by thyrotropin (TSH). Inositol uptake was also increased but there was no spontaneous increase of the generation of inositol phosphates and this metabolism could be further activated by TSH. These positive responses to TSH are in agreement with the properties of TSH-stimulated thyroid cells in vitro and in vivo. They are compatible with the characteristics of mutated TSH receptors whose constitutive activation accounts for the majority of autonomous thyroid adenomas in Europe. The number of cycling cells, as evaluated by MIB-1 immunolabeling was low but increased in comparison with the corresponding quiescent tissue or normal tissue. The cycling cells are observed mainly at the periphery; there was very little apoptosis. Both findings account for the slow growth of these established adenomas. On the other hand, by thyroperoxidase immunohistochemistry, the whole lesion appeared hyperfunctional, which demonstrates a dissociation of mitogenic and functional stimulations. Thyroglobulin, TSH receptor, and E-cadherin mRNA accumulations were not modified in a consistent way, which confirms the near-constitutive expression of the corresponding genes in normal differentiated tissue. On the contrary, early immediate genes expressions (c-myc, NGF1B, egr 1, genes of the fos and jun families) were decreased. This may be explained by the proliferative heterogeneity of the lesion and the previously described short, biphasic expression of these genes when induced by mitogenic agents. All the characteristics of the autonomous adenomas can therefore be explained by the effect of the known activating mutations of genes coding for proteins of the TSH cyclic adenosine monophosphate (cAMP) cascade, all cells being functionally activated while only those at the periphery multiply. The reason of this heterogeneity is unknown.

Comparative wetting behavior of Sn-0.7Cu and Sn-0.7Cu-0.3Ni solders on Cu and Ni substrates

Electronic packaging industries are now in great challenge to find a suitable lead-free solder as an interconnection material to replace the conventional SnPb solders. Many solders such as SnCu, SnAg, SnAgCu, SnZn, SnBi have already been proposed as the replacement but none of them has reached the physical and metallurgical properties similar to the SnPb solder. However, wetting is one of the basic problems that make the lead-free solder inferior as compared to the SnPb solder. Therefore, alloying with the help of third, fourth or fifth element is the researchers' interest to improve the wetting behavior of lead-free solders. This paper describes the comparative wetting behavior of Sn-0.7Cu and Sn-0.7Cu-0.3Ni solders on Cu and Ni substrates. Wetting balance tests were performed to assess the wetting behaviors. Three different commercial fluxes namely no-clean (NC), non-activated (R) and water soluble organic acid (WS)fluxes were used to assess the wettability for three solder bath temperatures. It was found that Sn0.7Cu-03Ni solder exhibits better wettability on Cu substrate for NC and WS fluxes whereas reverse results were found for R-type flux. In the case of Ni substrate, Sn-0.7Cu-0.3Ni solder showed better wetting behavior compared to the well-known Sn-0.7Cu solder. Among the three fluxes, R-type flux showed the worst performance. Very large contact angles were documented for both solders with this flux. Higher solder bath temperature lowered the contact angles, increased the wetting forces and enhanced the wettability. Computer modeling of wetting balance test revealed that both the wetting force and meniscus height are inversely proportional to the contact angles. Modeling results also reveal that increase in solder bath depths and radiuses do not affect significantly on the wetting behavior.

Comparative antioxidant, prooxidant and cytotoxic activity of sigmoidin A and eriodictyol

Sigmoidin A (SGN) is a prenylated flavanone derivative of eriodictyol (ERD) with reported moderate antioxidant, antimicrobial and anti-inflammatory activity. Since ERD and other structurally similar antioxidant phenolic compounds have been shown to induce prooxidative macromolecular damage and cytotoxicity in cancer cells, the comparative in vitro effects of these structural analogues on cancer cell viability and Cu(II)-dependent DNA damage were studied. In the presence of Cu(II) ions, both SGN and ERD (7.4-236 µM) caused comparable concentration-dependent pBR322 plasmid DNA strand scission. The DNA damage induced by SGN and ERD could be abolished by ROS scavengers, glutathione (GSH) and catalase as well as EDTA and a specific Cu(I) chelator neocuproine. Both ERD and SGN readily reduce Cu(II) to Cu(I) suggesting a prooxidative mechanism of DNA damage. In a cell free system, ERD and SGN did also show comparable radical scavenging activity. SGN was, however, by an order of magnitude more cytotoxic to cancer cells than ERD and this effect was significantly attenuated by GSH suggesting a prooxidative mechanism of cell death. A depletion of intracellular GSH level by SGN in cancer cells is also demonstrated.

The art of auscultation: evaluating a patient's respiratory pathology

This article considers national policy drivers promoting the development of advanced assessment skills and practical procedures for the safe and effective use of the stethoscope in the clinical area. The evidence base underpinning effective use of the stethoscope in clinical practice is explored, including the preparation of the patient and the environment, applying infection control policies, and placing an emphasis on privacy and dignity. This is followed by a practical guide to auscultation technique of the respiratory system for nurses developing advanced practice skills.

The comparative advantage of the public sector in the development of urban water supply

This paper addresses the potential of public water operations in achieving developmental goals such as the Millennium Development Goals, and argues that the public sector has a comparative advantage in developing water services. The global importance of the public sector in urban water supply is examined through a review of current practice in the world's largest cities, including operational presence and distribution and ongoing trends. Empirical evidence shows that, in transition and developing countries, public operators are capable of undergoing successful reform. One explanatory factor is proposed to be the creation through the public sphere of highly interconnected networks among stakeholders. Such accountability networks act as vehicles for the generation and distribution of public knowledge among stakeholders, which in turn inform rational decision making on the reform and management of operations.

Comparative analysis of corporate risk management practices in Croatian and Slovenian companies

The paper explores differences as well as commonalities in corporate risk management practices and risk exposures in the large non-financial Slovenian and Croatian companies. Comparative analysis of survey results have revealed that the majority of analysed companies in both Croatia and Slovenia are using some form of risk management to manage interest-rate, foreign exchange, or commodity price risk. Regarding the intensity of influence of financial risks on the performance of the analysed companies, the results have shown that the price risk has the highest influence among the Slovenian as well as the Croatian companies. Croatian companies are more affected by currency risk than the Slovenian companies, while the interest-rate risk has been ranged as less important in comparison with commodity price and currency risks. The survey’s results have clearly indicated that Croatian and Slovenian non-financial companies manage financial risks primarily with simple risk management instruments such as natural hedging. In the case of derivatives use, forwards and swaps are by far the most important instruments in both countries, but futures as representatives of standardised derivatives and structured derivatives are more important in the Slovenian than in the Croatian companies.