Dynamical paths and universality in continuous variables open systems

We address the dynamics of quantum correlations in continuous variable open systems and analyze the evolution of bipartite Gaussian states in independent noisy channels. In particular, upon introducing the notion of dynamical path through a suitable parametrization for symmetric states, we focus attention on phenomena that are common to Markovian and non-Markovian Gaussian maps under the assumptions of weak coupling and secular approximation. We found that the dynamical paths in the parameter space are universal, that is they do depend only on the initial state and on the effective temperature of the environment, with non Markovianity that manifests itself in the velocity of running over a given path. This phenomenon allows one to map non-Markovian processes onto Markovian ones and it may reduce the number of parameters needed to study a dynamical process, e.g. it may be exploited to build constants of motions valid for both Markovian and non-Markovian maps. Universality is also observed in the value of Gaussian discord at the separability threshold, which itself is a function of the sole initial conditions in the limit of high temperature. We also prove the existence of excluded regions in the parameter space, i.e. of sets of states which cannot be linked by any Gaussian dynamical map.Comment: 7 pages, 2 figures, improved pictures and forma

Photoprotection in oxygenic photosynthesis: A reverse genetic study

La luce \ue8 essenziale per la fotosintesi e la vita sulla terra e tuttavia pu\uf2 diventare dannosa per le piante. Quando i fotoni vengono assorbiti in eccesso, rispetto alla capacit\ue0 del trasporto elettronico fotosintetico, si producono specie reattive dell'ossigeno che provocano fotoinibizione, limitando la crescita delle piante e la loro produttivit\ue0. Gli organismi fotosintetici hanno sviluppato meccanismi di fotoprotezione per prevenire/evitare i danni foto-ossidativi. Tra questi, il Non-Photochemical Quencing o NPQ \ue8 di particolare interesse. Il meccanismo di NPQ smorza gli stai eccitati della clorofilla catalizzando la dissipazione, sottoforma di calore, dell\u2019energia assorbita in eccesso. Nel corso degli ultimi decenni, molti sforzi sono stati fatti per chiarire i meccanismi alla base di questi processi. Oltre alla curiosit\ue0 accademica, la manipolazione della dissipazione termica e la sua regolazione in risposta agli stimoli ambientali sembra essere la chiave per aumentare sia la resistenza allo stress sia la produttivit\ue0 di cibo e combustibili. Durante mio dottorato ho usato un approccio di genetica inversa, sull\u2019organismo modello Arabidopsis thaliana, per dissezionare e caratterizzare il ruolo dei diversi componenti dei meccanismi di fotoprotezione, nonch\ue9 il loro contributo all\u2019acclimatazione agli stress abiotici. Di particolare interesse \ue8 stata la generazione e l'analisi di mutanti di diversi enzimi della via di biosintesi dei carotenoidi, di proteine antenna che legano i carotenoidi e di mutanti privi dellla capacit\ue0 di muovere i cloroplasti all\u2019interno della cellula per ridurre l\u2019assorbimento luminoso.Light is essential for photosynthesis and life on earth and yet it is harmful for plants. When photons are absorbed in excess with respect to the capacity of photosynthetic electron transport, reactive oxygen species are produced that causes photoinhibition, limiting plant growth and productivity. Oxygenic photosynthetic organisms have evolved photoprotective mechanisms to prevent/avoid photodamage. Among these, the Non-Photochemical Quenching (of chlorophyll fluorescence) or NPQ is of particular interest. NPQ has been reported to quench the chlorophyll excited states thus catalyzing the thermal dissipation of energy absorbed in excess. Over the past decades many efforts have been made to elucidate the mechanisms underlying these processes. Besides academic curiosity, manipulation of thermal dissipation rate and its regulation in response to environmental cues appears to be the key for both enhancing stress resistance and productivity for food and fuels. In my PhD I used a reverse genetic approach on the model organism Arabidopsis thaliana to disentangle and characterize the role of different components of photoprotective mechanisms as well as their contribution to acclimation to abiotic stresses. Of particular interest have been the generation and analysis of mutants defective in carotenoids biosynthesis, specific xanthophyll binding proteins and in the chloroplast light avoidance mechanism

Disturbed excitation energy transfer in Arabidopsis thaliana mutants lacking minor antenna complexes of photosystem II.

Abstract Minor light-harvesting complexes (Lhcs) CP24, CP26 and CP29 occupy a position in photosystem II (PSII) of plants between the major light-harvesting complexes LHCII and the PSII core subunits. Lack of minor Lhcs in vivo causes impairment of PSII organization, and negatively affects electron transport rates and photoprotection capacity. Here we used picosecond-fluorescence spectroscopy to study excitation-energy transfer (EET) in thylakoid membranes isolated from Arabidopsis thaliana wild-type plants and knockout lines depleted of either two (koCP26/24 and koCP29/24) or all minor Lhcs (NoM). In the absence of all minor Lhcs, the functional connection of LHCII to the PSII cores appears to be seriously impaired whereas the "disconnected" LHCII is substantially quenched. For both double knock-out mutants, excitation trapping in PSII is faster than in NoM thylakoids but slower than in WT thylakoids. In NoM thylakoids, the loss of all minor Lhcs is accompanied by an over-accumulation of LHCII, suggesting a compensating response to the reduced trapping efficiency in limiting light, which leads to a photosynthetic phenotype resembling that of low-light-acclimated plants. Finally, fluorescence kinetics and biochemical results show that the missing minor complexes are not replaced by other Lhcs, implying that they are unique among the antenna subunits and crucial for the functioning and macro-organization of PSII

Different Roles of α- and β-Branch Xanthophylls in Photosystem Assembly and Photoprotection

Xanthophylls (oxygenated carotenoids) are essential components of the plant photosynthetic apparatus, where they act in photosystem assembly, light harvesting, and photoprotection. Nevertheless, the specific function of individual xanthophyll species awaits complete elucidation. In this work, we analyze the photosynthetic phenotypes of two newly isolated Arabidopsis mutants in carotenoid biosynthesis containing exclusively alpha-branch (chy1chy2lut5) or beta-branch (chy1chy2lut2) xanthophylls. Both mutants show complete lack of qE, the rapidly reversible component of nonphotochemical quenching, and high levels of photoinhibition and lipid peroxidation under photooxidative stress. Both mutants are much more photosensitive than npq1lut2, which contains high levels of viola- and neoxanthin and a higher stoichiometry of light-harvesting proteins with respect to photosystem II core complexes, suggesting that the content in light-harvesting complexes plays an important role in photoprotection. In addition, chy1chy2lut5, which has lutein as the only xanthophyll, shows unprecedented photosensitivity even in low light conditions, reduced electron transport rate, enhanced photobleaching of isolated LHCII complexes, and a selective loss of CP26 with respect to chy1chy2lut2, highlighting a specific role of beta-branch xanthophylls in photoprotection and in qE mechanism. The stronger photosystem II photoinhibition of both mutants correlates with the higher rate of singlet oxygen production from thylakoids and isolated light-harvesting complexes, whereas carotenoid composition of photosystem II core complex was not influential. In depth analysis of the mutant phenotypes suggests that alpha-branch (lutein) and beta-branch (zeaxanthin, violaxanthin, and neoxanthin) xanthophylls have distinct and complementary roles in antenna protein assembly and in the mechanisms of photoprotection

A quadruple mutant of Arabidopsis reveals a β-carotene hydroxylation activity for LUT1/CYP97C1 and a regulatory role of xanthophylls on determination of the PSI/PSII ratio

<p>Abstract</p> <p>Background</p> <p>Xanthophylls are oxygenated carotenoids playing an essential role as structural components of the photosynthetic apparatus. Xanthophylls contribute to the assembly and stability of light-harvesting complex, to light absorbance and to photoprotection. The first step in xanthophyll biosynthesis from α- and β-carotene is the hydroxylation of ε- and β-rings, performed by both non-heme iron oxygenases (CHY1, CHY2) and P450 cytochromes (LUT1/CYP97C1, LUT5/CYP97A3). The Arabidopsis triple <it>chy1chy2lut5 </it>mutant is almost completely depleted in β-xanthophylls.</p> <p>Results</p> <p>Here we report on the quadruple <it>chy1chy2lut2lut5 </it>mutant, additionally carrying the <it>lut2 </it>mutation (affecting lycopene ε-cyclase). This genotype lacks lutein and yet it shows a compensatory increase in β-xanthophylls with respect to <it>chy1chy2lut5 </it>mutant. Mutant plants show an even stronger photosensitivity than <it>chy1chy2lut5</it>, a complete lack of qE, the rapidly reversible component of non-photochemical quenching, and a peculiar organization of the pigment binding complexes into thylakoids. Biochemical analysis reveals that the <it>chy1chy2lut2lut5 </it>mutant is depleted in Lhcb subunits and is specifically affected in Photosystem I function, showing a deficiency in PSI-LHCI supercomplexes. Moreover, by analyzing a series of single, double, triple and quadruple Arabidopsis mutants in xanthophyll biosynthesis, we show a hitherto undescribed correlation between xanthophyll levels and the PSI-PSII ratio. The decrease in the xanthophyll/carotenoid ratio causes a proportional decrease in the LHCII and PSI core levels with respect to PSII.</p> <p>Conclusions</p> <p>The physiological and biochemical phenotype of the <it>chy1chy2lut2lut5 </it>mutant shows that (i) LUT1/CYP97C1 protein reveals a major β-carotene hydroxylase activity <it>in vivo </it>when depleted in its preferred substrate α-carotene; (ii) xanthophylls are needed for normal level of Photosystem I and LHCII accumulation.</p

An Edge-based Architecture for Phasor Measurements in Smart Grids

This paper investigates the application of Kubernetes and Edge computing technologies to operate IT services in the context of power systems and smart grids. Traditional services for grid monitoring such as Phasor Measurement Units (PMUs) and Phasor Data Concentrators (PDCs) require a centralized architecture and a rigid networking infrastructure in order to properly function, which today is only achieved at the High Voltage (HV) transmission level. Furthermore, manual intervention is often the only option for PMUs/PDCs maintenance. In this work, the traditional PMU/PDC services were deployed as docker-containers in a decentralized Kubernetes cluster, which can represent any kind of geographically dispersed TCP/IP network. By leveraging remote orchestration, several key benefits are achieved: (1) no manual reconfiguration of the PMU-PDC communications upon network reconfiguration, (2) automatic PMU traffic redirection in case of PDC service redeployment in a different location, and (3) reduced data-loss upon PDC failure and enhanced overall system resiliency due to minimized ICT services down-time

Light-Harvesting Complex Stress-Related Proteins Catalyze Excess Energy Dissipation in Both Photosystems of Physcomitrella patens

Two LHC-like proteins, Photosystem II Subunit S (PSBS) and Light-Harvesting Complex Stress-Related (LHCSR), are essential for triggering excess energy dissipation in chloroplasts of vascular plants and green algae, respectively. The mechanism of quenching was studied in Physcomitrella patens, an early divergent streptophyta (including green algae and land plants) in which both proteins are active. PSBS was localized in grana together with photosystem II (PSII), but LHCSR was located mainly in stroma-exposed membranes together with photosystem I (PSI), and its distribution did not change upon high-light treatment. The quenched conformation can be preserved by rapidly freezing the high-light-treated tissues in liquid nitrogen. When using green fluorescent protein as an internal standard, 77K fluorescence emission spectra on isolated chloroplasts allowed for independent assessment of PSI and PSII fluorescence yield. Results showed that both photosystems underwent quenching upon high-light treatment in the wild type in contrast to mutants depleted of LHCSR, which lacked PSI quenching. Due to the contribution of LHCII, P. patens had a PSI antenna size twice as large with respect to higher plants. Thus, LHCII, which is highly abundant in stroma membranes, appears to be the target of quenching by LHCSR

Turning a green alga red: engineering astaxanthin biosynthesis by intragenic pseudogene revival in Chlamydomonas reinhardtii.

SummaryThe green alga Chlamydomonas reinhardtii does not synthesize high-value ketocarotenoids like canthaxanthin and astaxanthin, however, a β-carotene ketolase (CrBKT) can be found in its genome. CrBKT is poorly expressed, contains a long C-terminal extension not found in homologues and likely represents a pseudogene in this alga. Here, we used synthetic re-design of this gene to enable its constitutive overexpression from the nuclear genome of C. reinhardtii. Overexpression of the optimized CrBKT extended native carotenoid biosynthesis to generate ketocarotenoids in the algal host causing noticeable changes the green algal colour to a reddish-brown. We found that up to 50% of native carotenoids could be converted into astaxanthin and more than 70% into other ketocarotenoids by robust CrBKT overexpression. Modification of the carotenoid metabolism did not impair growth or biomass productivity of C. reinhardtii, even at high light intensities. Under different growth conditions, the best performing CrBKT overexpression strain was found to reach ketocarotenoid productivities up to 4.5 mg L-1 day-1. Astaxanthin productivity in engineered C. reinhardtii shown here is competitive with that reported for Haematococcus lacustris (formerly pluvialis) which is currently the main organism cultivated for industrial astaxanthin production. In addition, the extractability and bio-accessibility of these pigments was much higher in cell wall deficient C. reinhardtii than the resting cysts of H. lacustris. Engineered C. reinhardtii strains could thus be a promising alternative to natural astaxanthin producing algal strains and may open the possibility of other tailor-made pigments from this host

Project for the prevention of caries in the developmental age: Experience in kindergartens of Northern Italy

AbstractIntroduction: Caries is one of the most widespread chronic diseases in the world and in Italy, only 78.4% of the 4 years children are caries free. Caries is defined as an infectious multifactorial pathology and between the etiological factors that contribute to its developing we find excessive sugar consumption. Correct behaviours adopted since the pediatric age will allow the child to learn how to improve their lifestyle, thus protecting health. Parents must therefore be properly educated to transmit healthy habits to their children from the early years. The main goal of our project is the prevention of caries in the developmental age by means of educational interventions on parents of children in the kindergarten (0–3 years). The study assesses the oral hygiene and food habits of the child and caregiver at baseline and after 3 months from the interventions (follow-up).Materials and Methods: We have used a questionnaire to collect the oral hygiene and food habits of parents and children. Next, dental hygienists and nutritionists organized training sessions for parents about correct oral hygiene and eating habits (in particular to reduce the sugar consumption). After 3 months from the training, the same questionnaires reconfirmed to evaluate the improvement of family habits.Results: The number of participants was reduce from 99 to 68 at the follow-up. With regards to eating habits, after training, almost the whole of the sample began to practice breakfast, indicating that the actual importance of this meal was understood. The habit of morning and afternoon snack, essential for a growing child, has increased (from 84% at baseline to 94% at follow-up and from 92% to 97% respectively). The bad habit of the after dinner snack, often even after teeth brushing, has decreased consistently (32% to 22%).The most significant advances in oral hygiene are those concerning tooth washing (86% to 97%), the average daily washing (1.27/die to 1.57/die), self-washing (33% to 30%), the use of toothpaste (85% to 90%) and fluoridated toothpaste (48% to 62%).Discussion: Starting from the data obtained from our pilot study, we think that it is essential to intervene already in the first years of life, when the subject is still "plastic" and can be trained to perform correct eating habits and oral hygiene. Furthermore, reducing the consumption of foods rich in sugar does not have a positive effect only on the onset of caries but also on the health of the individual