Renormalization of the Optical Response of Semiconductors by Electron-Phonon Interaction

In the past five years enormous progress has been made in the ab initio calculations of the optical response of electrons in semiconductors. The calculations include the Coulomb interaction between the excited electron and the hole left behind, as well as local field effects. However, they are performed under the assumption that the atoms occupy fixed equilibrium positions and do not include effects of the interaction of the lattice vibrations with the electronic states (electron-phonon interaction). This interaction shifts and broadens the energies at which structure in the optical spectra is observed, the corresponding shifts being of the order of the accuracy claimed for the ab initio calculations. These shifts and broadenings can be calculated with various degrees of reliability using a number of semiempirical and ab initio techniques, but no full calculations of the optical spectra including electron-phonon interaction are available to date. This article discusses experimental and theoretical aspects of the renormalization of optical response functions by electron-phonon interaction, including both temperature and isotopic mass effects. Some of the theoretical techniques used can also be applied to analyze the renormalization of other response functions, such as the phonon spectral functions, the lattice parameters, and the elastic constants.Comment: Latex 2.09, 28 pages, 13 Figs., 2 Tables, submitted to Phys. Stat. Sol.

Low energy high angular resolution neutral atom detection by means of micro-shuttering techniques: the BepiColombo SERENA/ELENA sensor

The neutral sensor ELENA (Emitted Low-Energy Neutral Atoms) for the ESA cornerstone BepiColombo mission to Mercury (in the SERENA instrument package) is a new kind of low energetic neutral atoms instrument, mostly devoted to sputtering emission from planetary surfaces, from E ~20 eV up to E~5 keV, within 1-D (2x76 deg). ELENA is a Time-of-Flight (TOF) system, based on oscillating shutter (operated at frequencies up to a 100 kHz) and mechanical gratings: the incoming neutral particles directly impinge upon the entrance with a definite timing (START) and arrive to a STOP detector after a flight path. After a brief dissertation on the achievable scientific objectives, this paper describes the instrument, with the new design techniques approached for the neutral particles identification and the nano-techniques used for designing and manufacturing the nano-structure shuttering core of the ELENA sensor. The expected count-rates, based on the Hermean environment features, are shortly presented and discussed. Such design technologies could be fruitfully exported to different applications for planetary exploration.Comment: 11 page

ELENA instrument science and testing: validation with particle beam

Understanding of particle emission processes from the Mercury surface is one of the major objectives of ELENAinstrument in the SERENA experiment on board of the BepiColombo mission. In particular the Ion-Sputteringprocess resulting from charged and energetic particles impacting on the surface can be investigated detectingthe low energetic neutral particles escaping from the planet. The possibility to identify the Ion-Sputtering signaltogether with back-scattered particles and neutrals generated by charge exchange is strictly linked with the newtechnology capability to measure low energetic neutral atoms. This goal can be addressed thanks to a new&oldapproach for the neutral atoms measurement: a well known Time of Flight system enhanced with a new kind ofStart section able to define the start time of the entrance in the ToF path without interacting with the particles anddirectly follow to the Stop detector. The Start section is a shutter composed by two membranes with nanometricslits realized in a large area (1cm2) and oscillating at several frequencies to open and close the entrance of ToFsection. This system is never used before in space mission.The IFSI-INAF Ion beam facility in Rome is devoted to the ELENA testing. The crucial point of the shutteringsystem interaction with particle beam is investigated. The first results demonstrate the good functionality of thiskind of system: capability of the shutter to Open and Close the entrance respect to an ion beam is tested with aMCP stop detector. In this poster we present the IFSI activity in the frame of ELENA science requirement togetherwith the experimental activity devoted to instrument verification

Etruscan political history - from the beginning till the end

U radu je prikazana politička povijest Etruščana od početka njihovog djelovanja pa sve do kraja, odnosno do 90. godine prije Krista, kada je Julijevim i Kalpurnijevim zakonom o građanskom pravu (Lex Iulia, Lex Calpurnia de civitate) cijela Etrurija prešla pod upravu Rima te nestala s povijesne i političke karte. Uvodni dio govori o podrijetlu Etruščana, od villanovske kulture pa sve do pitanja podrijetla samih Etruščana. Zbog više teorija o podrijetlu, u radu su obuhvaćene tri glavne teorije: istočna, sjeverna te teorija o autohtonom podrijetlu. Sljedeći je dio rada ekspanzija Etruščana, njihovo oblikovanje kao „nacije“, ekonomija, jezik i pismo. U arhajskom razdoblju dolazi do aktivnog susreta s Grcima, Kartažanima, Galima, te naposljetku, i Rimljanima. Etruščani su bili odlični pomorci (pirati) pa se u radu i navodi jedna od velikih bitki, a to je „bitka kod Alalije“ i njezine posljedice za Etruriju. Dolaskom Rima na političku scenu počinje pad moći Etrurije, teritorijalno komadanje te na kraju, asimilacija. Na početku Rimskog kraljevstva bila su tri etruščanska kralja: Tarkvinije I., Servije Tulije i Tarkvinije II. Oholi. Odlaskom zadnjeg kralja počinje razdoblje Rimske republike i konačni pad Etrurije. Etrurija nikada nije imala osjećaj zajedništva nacionalnog karaktera pa je to često bio uzrok poraza protiv Rima. Posljednji trenuci borbe protiv Rima bili su sklapanje saveza s ostalim narodima (Galima, Umbrima, Samnićanima) kako bi se oduprijeli rastućoj moći Rima. Poraz za porazom doveo je Etruriju pod vlast Rima, pa na kraju i do asimilacije

Constantine the Great

U radu se analizira život i dijelo Konstantina Velikog prema podacima iz dostupne literature. Podaci pružaju uvid u život Konstantina i kakav je on imao utjecaj na kršćanstvo u ono vrijeme. U obrađenoj cjelini, Konstantin s punim nazivom dobiva još naziv „Veliki“. Obradom podataka iz sekundarnih izvora i literature prikazano je njegov život, politički uspon od početaka, administrativna i vojna reorganizacija Carstva, gradnja nove buduće prijestolnice budućih careva – Konstantinopolis te donošenje „Milanskog edikta“ kao veliku nadu za cijeloukupno kršćansko stanovništvo. Daljnom obradom podataka prikazana je važnost riješavanja arijevskog pitanja te sazivanje Nicejskog koncila, tj sabora kojim je to pitanje riješeno

La Posibilidad del Siglo

A journey from 1989 to today to consider the era of populism, theorized by Ernesto Laclau and Chantal Mouffe, in its anti-essentialist, hegemonistic and criticism of traditional Marxism and prepare the ground for a possible era of militancy.Un recorrido desde 1989 hasta hoy para considerar la era del populismo, teorizado por Ernesto Laclau y Chantal Mouffe, en sus contribuciones anti-essencialistas, hegemonistas y de crítica al marxismo tradicional y plantear una era de la militanci

Genomic and physiological characterization of Bacilli isolated from salt-pans with plant growth promoting features

© The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Petrillo, C., Castaldi, S., Lanzilli, M., Selci, M., Cordone, A., Giovannelli, D., & Isticato, R. Genomic and physiological characterization of Bacilli isolated from salt-pans with plant growth promoting features. Frontiers in Microbiology, 12, (2021): 715678, https://doi.org/10.3389/fmicb.2021.715678.Massive application of chemical fertilizers and pesticides has been the main strategy used to cope with the rising crop demands in the last decades. The indiscriminate use of chemicals while providing a temporary solution to food demand has led to a decrease in crop productivity and an increase in the environmental impact of modern agriculture. A sustainable alternative to the use of agrochemicals is the use of microorganisms naturally capable of enhancing plant growth and protecting crops from pests known as Plant-Growth-Promoting Bacteria (PGPB). Aim of the present study was to isolate and characterize PGPB from salt-pans sand samples with activities associated to plant fitness increase. To survive high salinity, salt-tolerant microbes produce a broad range of compounds with heterogeneous biological activities that are potentially beneficial for plant growth. A total of 20 halophilic spore-forming bacteria have been screened in vitro for phyto-beneficial traits and compared with other two members of Bacillus genus recently isolated from the rhizosphere of the same collection site and characterized as potential biocontrol agents. Whole-genome analysis on seven selected strains confirmed the presence of numerous gene clusters with PGP and biocontrol functions and of novel secondary-metabolite biosynthetic genes, which could exert beneficial impacts on plant growth and protection. The predicted biocontrol potential was confirmed in dual culture assays against several phytopathogenic fungi and bacteria. Interestingly, the presence of predicted gene clusters with known biocontrol functions in some of the isolates was not predictive of the in vitro results, supporting the need of combining laboratory assays and genome mining in PGPB identification for future applications

Bacterioplankton diversity and distribution in relation to phytoplankton community structure in the Ross Sea surface waters

© The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Cordone, A., D’Errico, G., Magliulo, M., Bolinesi, F., Selci, M., Basili, M., de Marco, R., Saggiomo, M., Rivaro, P., Giovannelli, D., & Mangoni, O. Bacterioplankton diversity and distribution in relation to phytoplankton community structure in the Ross Sea surface waters. Frontiers in Microbiology, 13, (2022): 722900, https://doi.org/10.3389/fmicb.2022.722900.Primary productivity in the Ross Sea region is characterized by intense phytoplankton blooms whose temporal and spatial distribution are driven by changes in environmental conditions as well as interactions with the bacterioplankton community. However, the number of studies reporting the simultaneous diversity of the phytoplankton and bacterioplankton in Antarctic waters are limited. Here, we report data on the bacterial diversity in relation to phytoplankton community structure in the surface waters of the Ross Sea during the Austral summer 2017. Our results show partially overlapping bacterioplankton communities between the stations located in the Terra Nova Bay (TNB) coastal waters and the Ross Sea Open Waters (RSOWs), with a dominance of members belonging to the bacterial phyla Bacteroidetes and Proteobacteria. In the TNB coastal area, microbial communities were characterized by a higher abundance of sequences related to heterotrophic bacterial genera such as Polaribacter spp., together with higher phytoplankton biomass and higher relative abundance of diatoms. On the contrary, the phytoplankton biomass in the RSOW were lower, with relatively higher contribution of haptophytes and a higher abundance of sequences related to oligotrophic and mixothrophic bacterial groups like the Oligotrophic Marine Gammaproteobacteria (OMG) group and SAR11. We show that the rate of diversity change between the two locations is influenced by both abiotic (salinity and the nitrogen to phosphorus ratio) and biotic (phytoplankton community structure) factors. Our data provide new insight into the coexistence of the bacterioplankton and phytoplankton in Antarctic waters, suggesting that specific rather than random interaction contribute to the organic matter cycling in the Southern Ocean.Samples were collected in the framework of Plankton biodiversity and functioning of the Ross Sea ecosystems in a changing Southern Ocean [P-ROSE – (PNRA16_00239)], and CDW Effects on glacial mElting and on Bulk of Fe in the Western Ross sea [CELEBeR – (PNRA16_00207)] projects – Italian National Antarctic Program – funded by the Ministry of Education, University and Research (MIUR), awarded to OM and PR, respectively. MM was supported by an Earth-Life Science Institute (Tokyo, Japan) visiting fellowship. This work was partially supported by the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No. 948972) to DG

Label-free discrimination of cells undergoing apoptosis by hyperspectral confocual reflectance imaging

Among the optical techniques used for exploring the properties of cells and tissues, those based on hyperspectral label-free analysis are particularly interesting due to their non-invasive character and their ability to fast collect a huge number of information on the different sample constituents and their spatial distribution. Here we present results obtained with a novel hyperspectral reflectance confocal microscope of label-free discrimination of cells undergoing apoptosis. Our data, analyzed by means of a powerful statistical method, enable to obtain information on the biological status at a single cell level through the local measurement of reflectivity. Furthermore, an optical model of the local dielectric response gives an additional insight of the parameters linking the optical responsivity to the biological status