Colonization dynamics of the alien macrophyte Lemna minuta Kunth: a case study from a semi-natural pond in Appia Antica Regional Park (Rome, Italy)

Most studies describing biomass production of Lemna’ species (duckweeds) underline high growth rates of these species under controlled conditions. L. minuta’s growth, as well as its colonizing capability under natural conditions, has never been investigated, despite this species being the most widespread and invasive alien duckweed in Europe. In this study, the colonization dynamics of L. minuta were analysed through a 5 month field-experiment carried out in a semi-natural pond of 26.3 m in the city of Rome. Variations in plant coverage (m ), biomass pro- duced (g) and Relative Growth Rate (RGR, day of three main phases: (1) an initial phase (40 days), in which L. minuta grows moderately by covering just under 15 % of the pond surface; (2) an exponential phase (45 days), in which the duckweed grows intensively, until it completely covers the entire pond surface with a monolayer floating population; (3) an apparently stationary phase perpetuated in time, in which, instead, the species continues to grow in biomass, giving rise to a dense multilayer population 2.5 cm thick. L. minuta was able to colonize the entire pond surface in a few months of experiment, increasing its total bio- mass over 600 times respect to that initial. This underlines the species’ high biomass production in natural condi- tions. The RGR of L. minuta estimated at the end of the experiment amounts to 0.041 day (0.046 day , 0.006 day 0.126 day conditions for the native congeneric L. minor, showing a higher colonization capability of the alien species respect to the native ones. The characterization of the growth dynamics in field of the alien L. minuta provides information that could be useful for a better planning of management programs of natural wetlands invaded by this alien species, also with respect to its invasion control. Our findings suggest that in lentic environments, it is necessary to remove the species 2 2 –1 ), show that L. minuta has an growth of exponential type, consisting –1 –1 –1 , as average, minimum and maximum RGR, respectively) more than double of that calculated in similar –1 every 30 – 40 days for controlling this duckweed and prevent its future outbreaks locally. However, the complete removal of an entire L. minuta population from a natural site can result difficult and demanding but, combining a physical control of L. minuta with a subsequent biological one, it could make more effective the eradication action of the species from a site

Data acquisition electronics for NESTOR experiment: Project and tests

The NESTOR detector, at present under construction, is a telescope for high-energy neutrino astronomy. The apparatus, based on Cherenkov light detection, will be deployed in deep sea (about 4000m) near the S.W. Greek coast. We briefly describe the NESTOR detector, then we describe with more details the electronics for NESTOR data acquisition and transmission. The detector signals are sampled at 200MHz and all the resulting information are transmitted to the laboratory on 30km long electro-optical cable. The estimated Mean Time Between Failure of the full electronics system is greater than 20 years. Tests performed on the first prototypes confirm the main characteristics of these electronics: the dynamic range allowed for the signals is bigger than 1000, the pulse shape is reconstructed with an 8 bit ADC accuracy and the resolution in the measurement of the signal "threshold crossing time" is better than 200ps

Same riot/demo, different views (guest blog)

By Shakuntala Banaji In riposte to various UK newspapers’ and news channels’ conservative versions of reality, I would like to give an alternative account of what happened on the November 10th NUS and UCU demonstration against student fees and on the break-away part of it at 30 Millbank, the Conservative party HQ

Il licenziamento per motivi economici

Nella presente Sezione viene trattato il tema del licenziamento per giustificato motivo oggettivo connesso a ragioni di tipo economico, con particolare riferimento alle evoluzioni dell'interpretazione dottrinale e giurisprudenziale della fattispecie, anche alla luce degli interventi normativi più recenti (in particolare l'art. 1, comma 42 della legge n. 92 del 2012), così da fornire un quadro completo, seppur sintetico, sull’istituto