Biomedical subjects

Claudio Rossi

Publications and source records attributed to Claudio Rossi.

22 records · Page 2Linked to original sources

PubMed2002

Evidences of strong C-H...O bond in an o-carboranyl beta-lactoside in solution.

In this communication, the presence of a persistent intramolecular C-H....O bond in solution, has been evidenced by NMR spectroscopy and theoretical calculations. The molecules under study were o-carboranyl beta-glycoside derivatives, in which, the donor group was the activated CH of the carboranyl residue and the acceptor atom was the glycosidic oxygen. The strength of the interaction and the geometry of the atoms involved were determined by ab initio calculations.

Carbohydrate Conformation↗

PubMed2002

Evolutionary algorithms for the satisfiability problem.

Several evolutionary algorithms have been proposed for the satisfiability problem. We review the solution representations suggested in literature and choose the most promising one - the bit string representation - for further evaluation. An empirical comparison on commonly used benchmarks is presented for the most successful evolutionary algorithms and for WSAT, a prominent local search algorithm for the satisfiability problem. The key features of successful evolutionary algorithms are identified, thereby providing useful methodological guidelines for designing new heuristics. Our results indicate that evolutionary algorithms are competitive to WSAT.

Algorithms↗

PubMedDate not supplied

Penetration of solar radiation into the waters of Messina Strait (Italy).

The optical properties of the waters of five different stations, three located in the Messina Strait and two near the Strait (open sea), were analysed. Direct spectral measurements of the downward solar irradiance (290 - 800 nm) at different depths (0.5 m, 7 m, 10 m, 13 m, 20 m) were made using a cosine sensor connected to a spectroradiometer. Water samples were collected in the surface layer and their absorption spectra were analysed. The natural fluorescence profiles, along the water column, were determined using a fluorometer (SBE 911plus - Sea Teach). The spectral attenuation coefficient (K(lambda)), the variation of K(lambda) in different wavelength ranges (deltaK(deltalambda)), the wavelength corresponding to minimum value of K(lambda), the spectral depths of penetration of both 1% and 10% of the sub-surface irradiance values (P(lambda)), the depths of 1% of penetration of UVB, UVA and PAR, the depth ranges of the maxim concentration of Chl a and superficial CDOM were measured at each station. The maximum solar UVB penetration was about 65% of the photic zone and the maximum UVA penetration was nearly 100% (data of the Ionic sea station). Thus, a large part of the photic zone was exposed to UV radiation sufficient to cause a possible reduction in the photosynthetic activity of phytoplankton. The spectral penetration of solar radiation, especially UVB radiation, was significantly different in the three stations of the Strait with respect to the two stations studied in the open sea. This shows that variations in the spectral attenuation along the water column can be used as an indicator of properties of the water body.

Chlorophyll↗

PubMedDate not supplied

The spatial distribution of optical properties in the ultraviolet and visible in an aquatic ecosystem.

In aquatic ecosystems, the UV and visible radiation environment is strongly influenced by variation in the chemical and physical parameters of the ecosystems. In shallow lakes, highly heterogeneous water characteristics produce a wide variety of optical environments. Such ecosystems require analysis approaches that consider a potential variability. In this study, 77 stations were used to characterize the optical properties of a shallow lake (open water surface 54 km(2)). The vertical attenuation of solar radiation at 305, 313, 320 and 340 nm and at photosynthetically active radiation was measured during the seasonal cycle. Dissolved organic matter (DOM), turbidity, fluorescence, pH, temperature, conductance and dissolved oxygen were simultaneously measured. The spatial variation of the extinction spectra of the dissolved fraction at each sampling station was also measured and analyzed between 270 and 400 nm. The spatial heterogeneity of the lake was examined by determining the distributions of the attenuation coefficients and biooptical parameters at high spatial resolution and describing the distributions in a series of maps. The methodology permitted a quantitative description of the interaction between solar radiation and aquatic ecosystems as well as a spatial classification of the dominating processes within the lake. This included the determination of the role played by DOM loading and changing chemical properties within the lake optical environment.

Ecosystem↗