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Discovering mithocondrial alterations in Parkinson's disease: the role of mitophagy impairment.
No full textParkinson's disease (PD) is one of the most prevalent neurodegenerative disorders, characterized by the loss of dopaminergic neurons in the Substantia nigra pars compacta. Although the cause of PD is currently unknown, strong evidences indicate that a complex interplay between several factors including genetic susceptibility, environmental factors, abnormal protein handling and oxidative stress could be involved. Many of the molecular pathways implicated in PD etiology converge on mitochondria, resulting in their dysfunction, which could impact on neuronal survival.
Given the importance of mitochondrial dysfunctions in PD, we decided to investigate the missed removal of damaged mitochondria due to mitophagy impairment as the possible trigger of pathogenesis. To this purpose, we characterized specific mitochondrial alterations in Substantia nigra specimens from PD patients, comparing them to what observed by inducing mitochondrial impairment in human neuroblastoma SH-SY5Y cells using dopamine or MPP+.
Since mitophagy impairment seems to play a central role in the development of this pathology, the second part of this thesis focused on mitochondrial alterations that occur in skin fibroblasts obtained from PARK2-mutated patients. As a result, we found that mutations in the PARK2 gene do not cause any significant morphological alterations in the mitochondrial network shape. Moreover, the proteomics analysis revealed an impairment of proteins involved in several mitochondrial functions.
Overall, this project contributes to a complete definition of the PARK2-related molecular signature, that will be crucial for providing new insights into disease mechanisms and identifying new therapeutic targets for this pathology
Back to plants for drug discovery: from ethnomedicine to more conventional approaches
No full textOver the last years, there is rekindling of interest in drug discovery from botanical resources. This thesis proposed two different approaches (from ethnomedicine to scholarly strategies) for drug discovery from medicinal plants, identifying the areas of knowledge involved and addressing the challenges encountered, with the aim of enhancing the chance of success of the overarching process.
The first approach consists to review the literature to increase understanding of a plant of interest and generate strong hypotheses for future drug development research on this plant.
Illustrating such an approach, we focused on Tithonia diversifolia (Hemsl.) A. Gray (TD). Knowledge about TD was collected from both online databases and non-electronic resources. Overall, a total of 1,804 reports have been collected. After subsequent duplicates removal and screening for relevant titles and abstracts, a total of 119 text articles were obtained and assessed for eligibility. Finally, 168 articles were selected, of which forty-nine were added after analyses of the reference lists of the included papers.
We found that all parts of the plant are valued in several cultures for a wide scope of ailments ranging from topical issues —wounds, skeleto-muscular disorders, abscesses, dermatological conditions, and stomach pains— to systemic disorders such as diabetes, malaria, fever, hepatitis and infectious diseases. Importantly, most of the ethnomedical claims of TD have been substantiated in several studies conducted in vitro and in vivo in animals. Sometimes, findings were conflicting and thanks to this review, we were able to assess the weight of evidence for each pharmacological effect of TD. The anti-inflammatory, antimalarial, antidiabetic, antioxidant and anticancer effects do stand out but there is also a stunning array of other relevant pharmacological effects. Chemically, a hundred of chemicals, mainly terpenoids and phenols, have been isolated from various TD extracts so far. Of these, some compounds including Tagitinin C have been linked to the pharmacology of TD. About the toxicological profile, we were able to conclude based on evidence that short-term oral administration of TD is relatively well-tolerated in animals when taken at doses less than 100 mg/kg.
The second approach consists to screen the ethnomedical knowledge of indigenous people to select the best plant candidate to launch a drug discovery campaign. So, we carried out a 6-month cross-sectional questionnaire-based survey to explore the use of medicinal plants (MP) in People living with HIV (PLHIV) in the city of Dschang (West Region, Cameroon).
Of the 247 HIV-infected respondents, 54.9% reported to use plants. MP users were then kindly invited to provide photographs and/or specimens of plants for botanical identification. A total of 70 MP, chiefly the herbs, were mentioned by informants (82.2% of total MP users, mean±SEM: 2.2±0.2 MP/subject, min 1, max 11), of which forty-nine have been botanically identified. Commonly reported pathological conditions or symptoms treated with MP included malaria (n = 27, 18.4% of total citations), cough (n = 20, 13.6%) and abdominal pain (n = 16, 10.9%). The benefits of using MP reportedly ranged from moderate (n = 60, 57.7%) to complete (n = 35, 33.7%) relief, while only 8 subjects (7.7% of MP users) reported no change in their terms. Interestingly, 2 subjects (33.3 % of respondents) denounced fatigue and weight loss.
We also observed that THPs were the main advisors of PLHIV on the use of MP. Thus, in the rest of our study, their knowledge and attitudes towards HIV/AIDS were surveyed aiming at understanding whether they may be an appropriate resource to assist in the scaling up of HIV prevention and treatment delivery services in Cameroon. 16 THPs were recruited by the chairperson of the Cooperative Society of Producers of Medicinal Plants of West Region based on their good reputation in traditional healing practice. Three of them acknowledged the use of MP to manage HIV diseases in their clients. All THPs who agreed to participate in the survey were also evaluated for their knowledge of HIV transmission, prevention and diagnosis. We found that their knowledge related to HIV was relatively low raising concern about their aptitude to effectively assist conventional health practitioners in fighting against HIV/AIDS.
Resulting from literature mining and ethnomedical claims is the adoption of a relevant pharmacological testing system. In any case, the testing systems should represent the biological activities that best match the ethnomedical uses of the selected plant species. In addition, it is important to bear in mind that plant extracts are complex mixtures containing various components and, therefore, their overall activity results from interactions between their naturally occurring ingredients.
It is with this background that we conducted a study of comparison of the effects of a whole extract of a particular strain of Cannabis sativa L. to that of cannabidiol (CBD). We knew cannabis is endowed with a potent anti-inflammatory effect attributable mainly to CBD, but also to its entourage. This mechanism by which other compounds occurring in cannabis may contribute to its clinical effects has been espoused as an “entourage effect”. The concept of entourage effect was first introduced in 1998 by Ben-Shabat and Raphael Mechoulam but still, there was no hard evidence that the entourage effect is real. So, thanks to a collaboration with a pharmaceutical company, we grew a particular strain of cannabis deprived of THC and standardized in 5% CBD (CM5). Then, we tested the effects of an extract of CM5 in parallel to that of pure CBD at equimolar concentrations on neutrophil functions including oxidative metabolism, migration and production of proinflammatory cytokines.
Results show that CM5 0.05-50 μg/mL and CBD 10-8-10-5 M inhibit the neutrophil functions including ROS production, cell migration, mRNA levels of proinflammatory cytokines (but at the protein level, only TNF-a was inhibited) to a comparable extent, indicating that CBD may be the main responsible of the anti-inflammatory effects of Cannabis. The effects of CBD and CM5 show however remarkable differences in terms of potency and efficacy, suggesting that beyond CBD, other components of cannabis may contribute to its biological effects. As a whole, such results support the use of cannabis and CBD to stem inflammation, however also warrant in-depth investigation of the underlying cellular and molecular mechanisms to better exploit their therapeutic potential
Axial stereogenicity for designing inherently chiral organic semiconductors.
Full text linkThe topic of my research is focused on the discovery and development of new inherently chiral molecules that, due to their peculiar properties, can be used both as semiconductive material and, when the molecules are deposited as an enantiopure film, as surfaces able to enantiorecognize chiral probes.
In the last years, the interest for the organic semiconductors has increased and especially multi-thiophene molecules have attracted considerable attention. Such multi-thiophene materials are obtained by chemical or electrochemical oxidation of a monomer and they are insulator in neutral state but become conductor after p- or n-type doping.
Chirality is generally introduced in the polyconjugated semiconductors by attaching chiral pendants to the electroactive backbone but these materials give relevant chirality manifestations only under particular experimental conditions [1]. The idea on which is based this research project is to design a class of compounds that could strictly correlate the conductive polythiophenes backbone to the chirality properties. This requirement is satisfied by the exploitation of the inherent chirality that is based on the concept that the scaffold constituting the stereogenic element responsible for chirality is also the functional group responsible for properties.
The peculiarities of the inherently chiral system are that the chirality results from a tailored torsion produced along the conducting oligothiophene backbone, the stereogenic core responsible for chirality is an atropoisomeric bi-thiophene or bi-pyrrole, and the same conjugated system responsible for the electro-optical properties is also responsible for molecular chirality.
The first member of this new class, nicknamed BT2T4 (because it consists in a bithianaphthene scaffold leading four thiophenes), showed outstanding properties such as a very high racemization barrier, great chiroptical properties and, deposited as an enantiopure polymeric film on an electrode, it showed amazing enantiorecognition ability [2].
Furthermore, BT2T4 was chemical oxidized by FeCl3 and the mixture of the oligomers was analyzed through HR MALDI spectrometry giving a very surprising result since all the oligomers, namely dimers, trimers and superior oligomers, were found to be cyclic and not open and linear [3].
Prompted by these outstanding results, during the first year of the PhD research we modified the structure of BT2T4 in order to obtain new inherently chiral compounds following two different strategies. The first one is based on the bithiophene tail elongation in order to achieve, after the oxidation, cyclic compounds with bigger cavity. The second strategy, on the other hand, aims to achieve a compound where the bithiophene tails are blocked in a rigid coplanar structure: the rigidity of the system indeed should provide material endowed with better optoelectronic properties.
All these compounds were prepared according to the same general procedure starting from the 2,2’-dibromo-3,3’- bithianaphatene that was functionalized with different “pendants” through a Stille reaction.
As shown in figure 2 the selected “pendants” were the ter-thiophene (BT2T6), the 3',4'-dibutyl-2,2':5',2''-terthiophene (BT2T6 Bu), the dithienopyrrole-N-octyl (BT2DTP2), the dithienopyrrole-N-methyl-phenyl (BT2DTP2 Ph) and the 4,7-di(thiophen-2-yl)benzo[c][1,2,5]thiadiazole (BT2BTD2).
In particular, the introduction of a benzothiadiazole system has a double role: to extend the pendant lenth and, at the same time, to lead to a compound exhibiting optical properties slightly different from the other monomers (i.e. high quantum yields and λ absorption red-shifted).
After one year, we reached many promising results: we could confirm that the modification introduced on the BT2 scaffold leads to monomers able to oligomerize through chemical and electrochemical oxidation producing cyclic oligomers with different dimension and shape. We analyzed both monomers and oligomers by different techniques. Futhermore, some of them were separated into enantiomers and their chiroptical properties were investigated.
As expected, the compound nicknamed BT2BTD2 has remarkable properties, especially from an optical point of view but unfortunately, we could not exploit it due to its low solubility. For this reason, we planned to modify the structure of the monomer in order to improve the solubility by introducing four EDOT units in place of the four thiophenes.
Unfortunately, due to the low solubility of the benzothiadiazole-bis-EDOT (BTDE) it was not possible to obtain the target monomer through the classical synthetic scheme which requires a Pd (0) catalyzed Stille reaction. However, since the bare BTDE appeared an interesting monomer, we investigated its chemical and electrochemical copolymerization in the presence of 3,3’-bithianaphtene. These experiments were carried out in the group of prof. S. Ludwigs of the University of Stuttgart, where I spent my abroad period, exploiting the expertise of the group in the polymer synthesis and electrochemical analysis.
Since both chemical and electrochemical oxidation did not give the expected results, we moved our attention to the possibility to achieve a donor-acceptor (D-A) copolymer by copolymerization of the benzothiadiazole-bis-EDOT with the branched terthiophene, nicknamed T3, deeply investigated in that group [4,5]. D-A polymers have recently attracted particular interest since they exhibit a reduced band-gap, due to their in-chain donor-acceptor interaction and for this reason they are used as light-harvesting system in solar cells. Furthermore, besides a long time focused on electrochemical analysis, during the period spent in Germany I synthetized two new compounds.
In order to investigate the role of ramification, we prepared a product with the same number of thiophenes as BT2T6 but with a branched structure by functionalizing the atropisomeric scaffold with two T3 units.
On the other hand, we synthetized a compound functionalized with four EDOT units, nicknamed BT2E4 which should have provided a material with interesting properties, being EDOT electron-richer than thiophene and ubiquitous in the electroactive materials.
During my third year, we focused our attention on a new class of inherently chiral monomer based on the scaffold of the 2,2’-biindole. The design of the new class has two main motivations:
the 2,2’-biindolic core is more electron rich than that of 3,3’-bithianaphtene and the first two oxidations result at an oxidative potential particularly low. This could allowed to discriminate analytes in a different potential window.
the nitrogen atom can be functionalized, tuning solubility and processability of the final material.
Especially interesting is the monomer derived from the introduction of a chiral pendant, namely the (R)- or (S)-phenylethyl group, that leads to the formation of two diastereoisomers, theoretically separable through a classical method, avoiding the chiral HPLC.
Indeed, the major disadvantage presented by the compounds investigated until now is the fact that their separation into antipodes must be performed through HPLC on a chiral stationary phase. Developing a method that could allow to avoid this tedious step would be an appealing target. In figure 5 are reported two other monomers synthetized according to this strategy: the first is characterized by the presence of two carboxylic groups that could allowed a classical resolution through the formation of diastereoisomeric salts with a chiral base. The second, on the other hand, was obtained as an enantiopure compound through an enantioselective synthesis starting from an enantiopure precursor obtained, in turn, by resolution with camphosulfonic acid.
In addition, due to the remarkable properties showed by BT2BTD2, we decided to introduce the benzothiadiazole system on the 2,2’-biindole scaffolds obtaining the first example of a biindole with a pendant different from the bithiophene. The presence of the nitrogen atoms allows the functionalization with two hexylic chains that strongly increase the solubility of the monomer, overcoming the problem found for BT2BTD2.
In conclusion, after three years research on inherently chiral electroactive materials new compounds, based on 3,3’-bithianaphtene and 2,2’-biindole core, were synthetized and fully characterized.
The new frontier of this kind of inherently chiral monomers results to be the achievement of enantiopure compounds without the use of chiral HPLC and some preliminary interesting results have been obtained.
[1] Janssen et al.; J. Molecular Structure, 2000, 521, 285;
[2] Sannicolò, F.; Benincori, T. et al.; Angew. Chem., Int Ed., 2014, 53, 2623;
[3] Sannicolò, F.; Benincori, T. et al.; Chemistry: an European Journal, 2014, 20, 15261;
[4] Link, S.; Ludwigs, S. et al.; Langmuir, 2013, 29, 15463;
[5] Goll, M.; Ludwigs, S. et al.; Beilstein J. Org. Chem, 2015, 11, 335;
[6] Abbiati, G.; Arcadi, A. el al.; Tetrahedron, 2006, 62, 3033
Privacy preference mechanisms in Personal Data Storage (PDS).
Full text linkIn this thesis, we study frameworks for managing user's privacy when disclosing personal data with third parties from Personal Data Storage (PDS). PDS is a secure digital space which allows individuals to collect, store, and give access to third parties. So, PDS has inaugurated a substantial change to the way people can store and control their personal data, by moving from a service-centric to a user-centric model. Up to now, most of the research on PDS has focused on how to enforce user privacy preferences and how to secure data stored into the PDS. In contrast, this thesis aims at designing a Privacy-aware Personal Data Storage (P-PDS), that is, a PDS able to automatically take privacy-aware decisions on third parties access requests in accordance with user preferences. This thesis first demonstrates that semi-supervised learning can be successfully exploited to make a PDS able to automatically decide whether an access request has to be authorized or not. Furthermore, we have revised our first contribution by defining strategies able to obtain good accuracy without requiring too much effort from the user in the training phase. At this aim, we exploit active learning with semi-supervised approach so as to improve the quality of the labeled training dataset. This ables to improve the performance of learning models to predict user privacy preferences correctly.
Moreover, in the second part of the thesis we study how user's contextual information play a vital role in term of taking decision of whether to share personal data with third parties. As such, consider that a service provider may provide a request for entertainment service to PDS owner during his/her office hours. In such case, PDS owner may deny this service as he/she is in office. That implies individual would like to accept/deny access requests by considering his/her contextual information. Prior studies on PDS have not considered user's contextual information so far. Moreover, prior research has shown that user privacy preferences may vary based on his/her contextual information. To address this issue, this thesis also focuses to implement a contextual privacy-aware framework for PDS (CP-PDS) which exploits contextual information to build a learning classifier that can predict user privacy preferences under various contextual scenarios. We run several experiments on a realistic dataset and exploiting groups of evaluators. The obtained results show the effectiveness of the proposed approaches
Cytoplasmic localization of HTLV-1 HBZ oncoprotein: a biomarker of HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP)
Full text linkHuman T cell lymphotropic virus type 1 (HTLV-1) is the etiological agent of a severe form of T cell neoplasia called Adult T cell Leukaemia (ATL) and of a neurologic disorder designated HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). The HBZ oncoprotein encoded by the minus strand of the HTLV-1 is thought to play an important role in both diseases.
The recent isolation in our laboratory of the first described monoclonal antibody against HBZ protein has now permitted to investigate in detail the cellular and biochemical features of endogenous HBZ. In this direction our laboratory has recently established that HBZ is a nuclear protein in cells of ATL patients. My thesis was predominantly focused in expanding the analysis particularly in HAM/TSP patients, to assess similarities and/or diversities of HBZ subcellular distribution with respect to ATL patients and asymptomatic HTLV-1 carriers.
Expression and localization of HBZ in peripheral blood mononuclear cells (PBMC) of ATL, HAM/TSP patients and in HTLV-1 asymptomatic carriers (AC) was analyzed by immunohistochemistry and confocal microscopy using the anti-HBZ 4D4-F3 mAb.
Analysis of patients with HAM/TSP unequivocally showed that HBZ-positive cells presented an exclusive, never reported, cytoplasmic localization of the viral oncogenic protein. Interestingly, experiment with leptomycin B indicated that HBZ could not shuttle between cytoplasm and nucleus. This strict HBZ cytoplasmic localization was at variance with the distribution of the other HTLV-1 oncogenic protein, Tax-1, that could localize both in the cytoplasm and the nucleus, and could be sequestered totally in the nucleus after leptomycin B treatment of the cells. Additional extensive analysis of cells from ATL patients and asymptomatic recipients confirmed, instead, a nuclear localization of HBZ.
I further supported this finding by studying HBZ and Tax-1 in the CIB cell line, a CD4+ IL-2-dependent T cell line derived from an HAM/TSP patient. The vast majority of CIB cells express significant amounts of HBZ exclusively in the cytoplasm, mostly in a speckle-like fashion. Tax-1 instead was expressed in 30% of the cells, either as a diffuse reticulum or distributed in a speckled-like fashion mainly in the cytoplasm. Interestingly, in cells co-expressing cytoplasmic HBZ and Tax-1, the two proteins did not co-localize, suggesting that they do not interact in vivo.
Our results establish for the first time a distinctive and diverse pattern of sub-cellular localization of endogenous HBZ protein. Furthermore, and of potential importance in the pathogenesis of HTLV-1-associated diseases, our data suggest that the endogenous localization of HBZ protein in different cellular compartments may correlate with the different forms of the HTLV-1-mediated diseases
Boring bacteria: a morphological research on bone diagenesis.
No full textPost mortem interval (PMI) estimation is a crucial issue in forensic medicine. To date, little is known about factors affecting post-mortem changes in hard tissues and it is still unclear who between exogenous bacteria from the environment and endogenous microbiota is the cause of microscopical alterations observed in human bone after death. Recent research highlighted an important role of endogenous bacteria in the earlier stages of the process. The aim of this study was to probe a potential endogenous model of human bone biodeterioration, based on the action of oral cavity endogenous microorganisms.
A total of seventy-four fragments of human bone samples were incubated with six bacterial strains, isolated from human tartar specimens. In a forty-eight months long prospective study, the onset and development of bone tissue alterations were serially analysed by scanning electron microscope.
The research furnished evidence that endogenous bacteria are able to bore into human dead bone, giving rise to microstructural changes morphologically indistinguishable from those observed in archaeological and forensic bone
Assessing Alpine Galliforms (Aves: Galliformes) vulnerability: modelling population trends and threats.
No full textThis research focused on the evaluation of Italian population trends and conservation threats of three Alpine Galliforms of conservation interest, Black grouse (Lyrurus tetrix), Alpine Rock ptarmigan (Lagopus muta helvetica) and Alpine Rock partridge (Alectoris graeca saxatilis). I performed a first-ever assessment of a medium term trend of the three species, exploiting all available data on annual counts and game bags, both as individual proxies and in an integrated fashion. According to the results, the current IUCN conservation statuses of the Italian populations seem appropriate. The integration of counts and bags helped improving estimates precision and reducing bias. Subsequently, I showed that intensive land abandonment has detrimental effects on Black grouse habitat suitability. The comparison of past and present land cover revealed a massive habitat suitability loss in Central Alps from the early 1980s, chiefly in the outer Alps and in wood pastures. Finally, I showed that marginal Rock ptarmigan populations living may display lower ecological plasticity in the use of habitat with respect to core populations and may not be able to adapt its behaviour to compensate for an increase in temperatures in the future. The project highlighted the need for a national survey scheme to plan robust conservation strategies and recommended the implementation of habitat management measures to directly or indirectly contrast the negative effects of global change
Phytocannabinoids as potential tools for ameliorating Rett Syndrome-like phenotype in Mecp2-null mice.
Full text linkRett syndrome (RTT) is an X-linked neurodevelopmental disorder with a prevalence rate of 1 in 10,000 females. RTT patients have apparently normal perinatal development until about 6-18 months of age, after which they undergo a period of rapid regression, characterized by the appearance of autistic features, stereotypic hand movements and loss of language. RTT girls also have seizures during childhood, breathing arrhythmias, develop scoliosis and lose mobility between ages 1 and 4 years.
Recently, there has been growing interest in the therapeutic potential of phytocannabinoids in the context of neurological diseases. Interestingly, several preclinical and clinical data support the ability of some phytocannabinoids to modulate cognitive and motor functions, mood and neuronal excitability, all of which are altered in RTT. Despite this evidence, so far no studies have addressed the potential therapeutic application of phytocannabinoids in RTT.
Based on these premises, the aim of this project was to evaluate the ability of chronic administration of the phytocannabinoids, cannabidivarin (CBDV) and cannabidiolic acid (CBDA), to affect neurological and motor defects as well as cognitive deficits in a mouse model of RTT, namely Mecp2 knockout (KO) mice.
To this aim, Mepc2 KO mice were treated daily with CBDV (or relative vehicle) at the doses of 0.2, 2, 20 or 200 mg/kg or CBDA (or relative vehicle) at the dose of 2 and 20 mg/kg from postnatal day (PND) 28 to 66. During the whole treatment schedule, motor and neurological signs were scored while short- and long-term memory deficits were evaluated at PND 41, 56 and 66. 24 hours after the last injection, brain tissues were collected to investigate the presence of alterations on neurotrophic factors (BDNF and IGF-1), inflammatory markers (CD11b, GFAP and TNFα) as well as components of the endocannabinoid system. The present findings provide for the first time direct evidence that CBDV and CBDA improve motor and neurological signs as well as cognitive deficits in Mecp2 KO mice. In particular, CBDV administration delays the appearance neurological and motor signs in Mecp2 KO mice in a time window between 5 and 7 weeks of age. Conversely, CBDA administration ameliorates motor signs only at later stages of the disease progression, i.e. 8 and 9 weeks of age. Remarkably, both phytocannabinoids exert a complete and enduring beneficial effect towards short- and long-term memory deficits in Mecp2 KO animals.
At the biochemical level, chronic treatments with CBDV and CBDA enhance the expression of both BDNF and IGF-1 and reduce microglia activation in the brain of Mecp2 KO mice. Moreover, Mecp2 deletion results in alterations in the endocannabinoid system that could likely sustain RTT-like phenotype, and chronic CBDV treatment further modulates them.
Although further studies are needed to directly assess the mechanism(s) through which CBDV and CBDA can improve RTT-like phenotype in Mecp2 KO mice, overall these findings suggest for the first time a potential therapeutic application of the phytocannabinoids CBDV and CBDA in the context of RTT
Analysis of the impacts of geomorphological disturbance on alpine and polar vegetation.
Full text linkUnder a context of climate change, polar and alpine regions have been demonstrated to be highly susceptible to climatic factors in various scientific fields. One aspect of susceptibility is treated in this thesis in terms of biogeomorphology, in particular for those geomorphic processes that couple the surficial displacements with the vegetation distribution. For these reasons, 3 study areas have been selected in polar (Svalbard and Antarctica) and alpine (Central Alps) regions to carry out this project. The methods used are different depending on the scale and the location of the target. On the Alps, at large scale, surface and climatic data have been used to produce thematic maps useful for a surface dynamic prediction model, while at landform scale, various system have been chosen to observe surface displacements (e.g., painted lines, height-o-meter) in relation to the vegetation distribution (vegetational relevé, line intercept). To quantify small-scale processes, a close-range photogrammetric application has been developed to produce detailed digital elevation models (DEMs) at a millimetric resolution. In the Arctic, ground thermistors and a time-lapse camera were set on a circumpolar active layer monitoring (CALM) grid to assess relationships among ground surface temperature (GST), snow distribution and active layer thickness (ALT) at a sub-metric scale. For understanding the effect of thaw depth on the CO2 fluxes on an arctic tundra environment, an infra-red gas analyzer (IRGA) system was coupled with a frost probing survey on different vegetation communities. In Antarctica, ground penetrating radar (GPR) with electrical resistivity tomography (ERT) have been utilized to detect ice content in 2 rock glaciers and an ice-core stratigraphy validated the digital findings.
The results of this project demonstrate that a novel prediction model that take in consideration both surface and climatic data (in particular snow distribution/persistence) to quantify mountainous surface displacement is possible. In addition, the annual surface velocities of 3 alpine rock glaciers were calculated and associated to different geomorphic processes that, in turn, create specific niches for alpine tundra species, able to tolerate specific substrate rates. Further, for small processes like needle ice, new minima of soil water content and cooling rate have been defined to initiate its formation, as well as the importance of minimum air temperature for the length of ice needles. Needle ice dynamic has been quantified and coupled with a high spatial variability as well as the absence of relation between frost heave and frost creep. In the Arctic we have demonstrated how small-scale spatial distribution of snow cover affects GST, leading in turn to a high spatial variability of ALT. This is majorly driven by the microtopography of the surface in terms of slope and convexity. ALT is also the best driver of net ecosystem exchange (NEE) in arctic tundra and, coupled with the importance of soil temperature for ecosystem respiration (ER), it is a novel key of interpretation of the arctic carbon cycle. In Continental Antarctica 2 active rock glaciers have been demonstrated to be ice-cored, differently than thought in the past. This led consequences for their proved glacial origin and also for the type of creep occurring within their bodies.
The strength of this project could be considered as the dependence of geomorphic processes (that induce surface displacements) on climatic factors, thus being able to be extrapolated under the future climate change scenarios. In addition, despite considerable differences in vegetation composition and functioning, the 3 distant study areas account for similar geomorphic processes that could be compared in future research to have a global understanding of surficial dynamics
Enhancing data privacy and security in Internet of Things through decentralized models and services
Full text linkexploits a Byzantine Fault Tolerant (BFT) blockchain, in order to perform collaborative and dynamic botnet detection by collecting and auditing IoT devices’ network traffic flows as blockchain transactions. Secondly, we take the challenge to decentralize IoT, and design a hybrid blockchain architecture for IoT, by proposing Hybrid-IoT. In Hybrid-IoT, subgroups of IoT devices form PoW blockchains, referred to as PoW sub-blockchains. Connection among the PoW sub-blockchains employs a BFT inter-connector framework. We focus on the PoW sub-blockchains formation, guided by a set of guidelines based on a set of dimensions, metrics and bounds