Landslide forecasting and factors influencing predictability

Forecasting a catastrophic collapse is a key element in landslide risk reduction, but it is also a very difficult task owing to the scientific difficulties in predicting a complex natural event and also to the severe social repercussions caused by a false or missed alarm. A prediction is always affected by a certain error; however, when this error can imply evacuations or other severe consequences a high reliability in the forecast is, at least, desirable. <br><br> In order to increase the confidence of predictions, a new methodology is presented here. In contrast to traditional approaches, this methodology iteratively applies several forecasting methods based on displacement data and, thanks to an innovative data representation, gives a valuation of the reliability of the prediction. This approach has been employed to back-analyse 15 landslide collapses. By introducing a predictability index, this study also contributes to the understanding of how geology and other factors influence the possibility of forecasting a slope failure. The results showed how kinematics, and all the factors influencing it, such as geomechanics, rainfall and other external agents, are key concerning landslide predictability

Aziridination of alkenes promoted by iron or ruthenium complexes

Molecules containing an aziridine functional group are a versatile class of organic synthons due to the presence of a strained three member, which can be easily involved in ring-opening reactions and the aziridine functionality often show interesting pharmaceutical and/or biological behaviours. For these reasons, the scientific community is constantly interested in developing efficient procedures to introduce an aziridine moiety into organic skeletons and the one-pot reaction of an alkene double bond with a nitrene [NR] source is a powerful synthetic strategy.Herein we describe the catalytic activity of iron or ruthenium complexes in promoting the reaction stated above by stressing the potential and limits of each synthetic protocol

Row orientation effects on whole-canopy gas exchange of potted and field-grown grapevines

The effects of canopy orientation (North-South vs. East-West) on total canopy assimilation (TCA) and transpiration (TCE) were evaluated on potted grapevines mounted on wheeled platforms for full swivel relation. Eight vines were assembled in pairs to form four canopy walls 2 m long, 1.1 m tall and 0.25-0.30 m wide. TCA and TCE readings were also taken in the field on four NS-oriented, hedgerow cordon-trained grapevines. Diurnal trends of TCA recorded on potted vines showed little variability when related to row orientation. The TCE pattern for EW followed essentially that of light intensity, whereas a NS orientation induced a marked decrease in TCE at midday before recovering in mid-afternoon. As a result, water use efficiency (WUE) in NS rows was higher during the midday hours. Total canopy water loss in NS was linearly correlated with estimates of intercepted light, suggesting that water use was a function of both, light intensity and canopy geometry (i.e. more light lost to the ground at noon, hence less transpiration). The results for the NS-oriented field-grown canopies differed to some extent from those of the pot experiments. TCA showed a more marked afternoon decline and TCE flattened at noon, though with no apparent decrease. WUE efficiency was lowest at the highest evaporative demand. The daily water loss of field vines could not be predicted by total light interception estimates only, indicating a more complex regulation of canopy transpiration than recorded on potted plants

Porphyrin-based homogeneous catalysts for the CO 2 cycloaddition to epoxides and aziridines

The direct insertion of carbon dioxide (CO2) into three-membered rings, such as epoxides and aziridines, represents a relevant strategy to obtain cyclic carbonates and oxazolidinones, which are two useful classes of fine chemicals. The synthesis of these compounds can be efficiently catalyzed by a combination of metal porphyrin complexes and various co-catalysts in homogeneous systems. The catalytic efficiency of these systems is discussed herein by taking into account both the characteristics of the metals and the nature of the co-catalysts, either when used as two-component systems or when combined in bifunctional catalysts. Moreover, mechanistic proposals of the CO2 cycloaddition processes are reported to provide a rationale of catalytic cycles in order to pave the way for designing more active and efficient catalytic procedures

Effects of canopy manipulations on whole-vine photosynthesis: Results from pot and field experiments

A two-year study was conducted with potted and field-grown grapevines to examine the effects of canopy restriction and leaf removal on total vine assimilation (TVA). TVA was measured using a flow-through gas exchange system equipped with flexible plastic chambers enclosing the entire canopy. Canopy restriction was applied to potted bush-shaped (BS) and field-grown spur-pruned cordon (SPC) vines on trellises to force the foliage into the smallest canopy volume. Leaf removal was performed on free cordon (FC) and SPC-trained vines at different dates to eliminate internal leaves shaded to varying extent. Canopy restriction reduced TVA more severely in the BS canopies than in the trellised SPC vines. Leaf removal elicited varying responses depending upon canopy shape, initial canopy density and leaf/fruit ratio. The FC vine showed no decrease in TVA after 27 % of its total leaf area had been removed, suggesting the occurrence of active photosynthetic compensation. TVA decreased with defoliation in the SPC vine, although the effect was mostly due to the leaf removal applied earlier in the season. In the FC vine a regression of total leaf area versus TVA showed maximum TVA at 6.0-6.5 m(2) of leaf area per meter of canopy. In SPC vines this relationship indicated a linear increase of TVA with leaf area and the lack of a saturation threshold under our experimental conditions. Sugar accumulation in the grapes of SPC vines correlated closely to the ratios leaf area/fruit and TVA/yield

Preliminary results on the use of a modified point quadrat method for estimating canopy structure of grapevine training systems

The reliability of a modified point quadrat method designed to describe the structure and seasonal canopy dynamics of the training systems simple curtain (SC) and traditional spur-pruned cordon (SPC) was tested in a two-year study. The method relies upon an unbiased sampling procedure as each canopy insertion is first identified within a ground-projected area by a random number generation routine (RND). From each insertion, the height of each contact with either leaves or clusters is then recorded along the vertical axis. Although the method suffered from a somewhat low percentage of effective insertions early in the season, the total leaf area-to-surface area ratio and the leaf layer number calculated for both canopy types are in accordance with those reported by others for high vigour canopies. Canopy dynamics showed an asymmetric growth in the SC starting at bloom. Both trellises resulted in similar canopy density indices and a high correlation was found between total leaf area and total number of leaf contacts

A custom-built simple system for conditioning and measurement of in situ whole-cluster transpiration

A custom-built, low-cost gas exchange system designed for conditioning of the cluster microclimate and for fully automated measurements of in situ whole-cluster transpiration is presented. Measurements were carried out on potted Sangiovese grapevines at the onset of veraison, To increase the range of variability in cluster transpiration, air streams of different vapor pressure deficits (VPD) were created by conditioning the temperature of the incoming flow. Heating was created and maintained for 10 d (26 June - 5 July) by air flow through a metal segment equipped with three 75 W (warm) or 100 W (hot) light bulbs, The cluster transpiration rates recorded for the unheated (control) clusters throughout the conditioning period varied from 0.18 to 0.28 mmol m-2 s-1. While the daily transpiration rates of clusters supplied with warm air were similar to those of the control, water loss began to decrease significantly in clusters treated with hot air from day 4 onward and stayed lower throughout the remaining conditioning period. The gas exchange system presented here proved sensitive enough to detect the typically low transpiration rates of berries during ripening; effects due to air heating could be separated from fluctuations caused by daily variation of weather.