Can Competition Outperform Collaboration? The Role of Misbehaving Agents

We investigate a novel approach to resilient distributed optimization with quadratic costs in a multi-agent system prone to unexpected events that make some agents misbehave. In contrast to commonly adopted filtering strategies, we draw inspiration from phenomena modeled through the Friedkin-Johnsen dynamics and argue that adding competition to the mix can improve resilience in the presence of misbehaving agents. Our intuition is corroborated by analytical and numerical results showing that (i) there exists a nontrivial trade-off between full collaboration and full competition and (ii) our competition-based approach can outperform state-of-the-art algorithms based on Weighted Mean Subsequence Reduced. We also study impact of communication topology and connectivity on resilience, pointing out insights to robust network design.Comment: Submitted to IEEE TAC - first revisio

Population dynamics and secondary production of Donax trunculus (Mollusca, Bivalvia) in the Gulf of Annaba (Northeast Algeria)

The population dynamics and secondary production of the wedge clam Donax trunculus were studied in the Gulf of Annaba (Northeast Algeria) monthly for one year at a site close to the Annaba port and the Seybouse river, affected by industrial and agricultural pollution (Sidi Salem), and at a site more distant from major pollution sources, but exploited by fishery (Echatt). The number of individuals (N) was lower at Sidi Salem (36–148 ind m-2) than at Echatt (63–272 ind m-2) in most sampling dates, while the biomass was more variable from one date to another, with no consistent pattern of differences between sites. The condition index (CI), although slightly higher at Sidi Salem than at Echatt, showed at both sites a major increase in March/April, June/July and October, reflecting two main periods of gonads development and increase in the level of stored reserves at the end of the reproductive period. Consistently, the recruitment of D. trunculus ran from April to October with a major peak of abundance in spring and a minor one in early fall. The maximum age of D. trunculus was 3 years and the growth rate was highest in the first year. Annual somatic production (P) was lower at Sidi Salem (0.773 g AFDM m-2 yr-1) than at Echatt (1.262 g AFDM m-2 yr-1), possibly reflecting a lower mean annual biomass at Sidi Salem (1.642 AFDM m-2) than at Echatt (3.046 AFDM m-2), while the annual P/B ratio was similar between the two sites (i.e. 0.471 and 0.414 yr-1, respectively). Lower N and P at Sidi Salem compared to Echatt are consistent with the proximity of Sidi Salem to the industrial port of Annaba and low hydrodynamic conditions which may favor the accumulation of pollutants, such as hydrocarbons. On the other hand, moderate secondary production of D. trunculus at Echatt compared to other Mediterranean sites may be due to excessive harvesting. We suggest that the low secondary production described in this study should be taken into account for the development of sustainable strategies of clam exploitation in the Gulf of Annaba. In particular, effort should be made to reduce land-based pollution and to regulate the collection of D. trunculus according to the life cycle and production potential of this species

I sistemi multi-agents e gli algoritmi di consenso

Recently, multi-agent systems have become a central study topic in many different disciplines including biology, engineering, physics, and social science. This has led to the emergence of large and constantly growing interdisciplinary research field, known as network science. The analysis of the mathematical models describing such systems has achieved significant results, but remains mostly an open research field, where many fundamental breakthroughs are expected in the next years. Such analysis is especially motivated by the quest for the development of tools for control and design of such systems. In this paper, we deal with consensus algorithms, an important example of design of multi-agent systems that has been inspired by the dynamics of cooperative systems in natural and social sciences

The role of vitamin deficiency in liver disease: To supplement or not supplement?

Over the past few years, growing interest has been shown for the impact of dietary requirements and nutritional factors on chronic diseases. As a result, nutritional programs have been reinforced by public health policies. The precise role of micronutrients in chronic liver disease is currently receiving particular attention since abnormalities in vitamin levels are often detected. At present, treatment programs are focused on correcting vitamin deficiencies, which are frequently correlated to higher rates of comorbidities with poor outcomes. The literature reviewed here indicates that liver diseases are often related to vitamin disorders, due to both liver impairment and abnormal intake. More specific knowledge about the role of vitamins in liver disease is currently emerging from various results and recent evidence. The most significant benefits in this area may be observed when improved vitamin intake is combined with a pharmacological treatment that may also affect the progression of the liver disease, especially in the case of liver tumors. However, further studies are needed

Enhanced photogeneration of polaron pairs in neat semicrystalline donor-acceptor copolymer films via direct excitation of interchain aggregates

We investigate the photogeneration of polaron pairs (PPs) in neat films of the semicrystalline donor–acceptor semiconducting copolymer PCPDTBT. Carefully selecting the solution-processing procedures, we obtain films with different amounts of crystallinity and interchain aggregation. We compare the photogeneration of PPs between the films by monitoring their photoinduced absorption in ultrafast pump–probe experiments, selectively exciting nonaggregated or aggregated polymer chains. The direct photoexcitation of interchain π-aggregates results in prompt (<100 fs) charge generation. Compared to the case where nonaggregated chains are excited, we find an 8-fold increase in the prompt PP to singlet-exciton ratio. We also show that highly crystalline lamellar nanostructures not containing π-stacked or any light-absorbing aggregates do not improve the efficiency of PP photogeneration. Our results show that light absorption from interchain aggregates is highly beneficial for charge photogeneration in semiconducting polymers and should be taken into account when optimizing film morphologies for photovoltaic devices

Simulation of High Conversion Efficiency and Open-circuit Voltages Of {\alpha}-si/poly-silicon Solar Cell

The P+ {\alpha}-Si /N+ polycrystalline solar cell is molded using the AMPS-1D device simulator to explore the new high efficiency thin film poly-silicon solar cell. In order to analyze the characteristics of this device and the thickness of N+ poly-silicon, we consider the impurity concentration in the N+ poly-silicon layer and the work function of transparent conductive oxide (TCO) in front contact in the calculation. The thickness of N+ poly-silicon has little impact on the device when the thickness varies from 20 {\mu}m to 300 {\mu}m. The effects of impurity concentration in polycrystalline are analyzed. The conclusion is drawn that the open-circuit voltage (Voc) of P+ {\alpha}-Si /N+ polycrystalline solar cell is very high, reaching 752 mV, and the conversion efficiency reaches 9.44%. Therefore, based on the above optimum parameters the study on the device formed by P+ {\alpha}-Si/N+ poly-silicon is significant in exploring the high efficiency poly-silicon solar cell.Comment: 8 pages 6figures, 1 table

Coherent phonons and the interplay between charge density wave and Mott phases in 1TT-TaSe2_{2}

1$T$-TaSe$_{2}$ is host to coexisting strongly-correlated phases including charge density waves (CDWs) and an unusual Mott transition at low temperature. Here, we investigate coherent phonon oscillations in 1$T$-TaSe$_{2}$ using a combination of time- and angle-resolved photoemission spectroscopy (TR-ARPES) and time-resolved reflectivity (TRR). Perturbation by a femtosecond laser pulse triggers a modulation of the valence band binding energy at the $\Gamma$-point, related to the Mott gap, that is consistent with the in-plane CDW amplitude mode frequency. By contrast, TRR measurements show a modulation of the differential reflectivity comprised of multiple frequencies belonging to the distorted CDW lattice modes. Comparison of the temperature dependence of coherent and spontaneous phonons across the CDW transition shows that the amplitude mode intensity is more easily suppressed during perturbation of the CDW state by the optical excitation compared to other modes. Our results clearly identify the relationship of the in-plane CDW amplitude mode with the Mott phase in 1$T$-TaSe$_{2}$ and highlight the importance of lattice degrees of freedom.Comment: 7 pages, 4 figures, supplemental materia

Small molecule induced reactivation of mutant p53 in cancer cells

The p53 cancer mutant Y220C is an excellent paradigm for rescuing the function of conformationally unstable p53 mutants because it has a unique surface crevice that can be targeted by small-molecule stabilizers. Here, we have identified a compound, PK7088, which is active in vitro: PK7088 bound to the mutant with a dissociation constant of 140 μM and raised its melting temperature, and we have determined the binding mode of a close structural analogue by X-ray crystallography. We showed that PK7088 is biologically active in cancer cells carrying the Y220C mutant by a battery of tests. PK7088 increased the amount of folded mutant protein with wild-type conformation, as monitored by immunofluorescence, and restored its transcriptional functions. It induced p53-Y220C-dependent growth inhibition, cell-cycle arrest and apoptosis. Most notably, PK7088 increased the expression levels of p21 and the proapoptotic NOXA protein. PK7088 worked synergistically with Nutlin-3 on up-regulating p21 expression, whereas Nutlin-3 on its own had no effect, consistent with its mechanism of action. PK7088 also restored non-transcriptional apoptotic functions of p53 by triggering nuclear export of BAX to the mitochondria. We suggest a set of criteria for assigning activation of p53

p63 expression in normal skin and usual cutaneous carcinomas

Background: p63 is a p53 homologue that is mapped to chromosome 3q27. This gene encodes six different isoforms, which have either transactivating or dominant negative effects on p53-reporter genes. It has been described that in contrast to p53, p63 seems not to be associated with tumor predisposition, as neither p63 knockout mouse models nor germline p63 mutations are related to an increased risk of tumorigenesis. It has been demonstrated that p63 is a reliable keratinocyte stem cell marker and that it is involved in the maintenance of the stem cell population. Scant data on p63 expression in normal skin, basal cell carcinomas (BCCs), keratoacanthomas and squamous cell carcinomas (SCCs) have been reported. We herein evaluated p63 expression in 16 BCCs, one keratoacanthoma and 13 SCCs. Methods: Immunohistochemistry according to the streptavidinbiotin-peroxidase technique, using the antibody 4A4 raised against all p63 isoforms, was performed. p63 expression was evaluated in epidermal cells and skin appendages. Semi-quantitative evaluation (–, π, ππ, πππ) of p63 expression in BCCs, keratoacanthoma and SCCs was carried out. Only nuclear expression was considered as specific. Results: p63 was expressed in the nuclei of epidermal basal and suprabasal cells, in the cells of the germinative hair matrix and the external root sheath of hair follicles, in the basal cells of the sebaceous gland and in the myoepithelial/basal cells of the sweat glands. All terminally differentiated cells were negative for p63. All BCCs showed ππto πππ immunoreactivity. At variance, keratoacanthomas and grade I and II SCCs showed variable p63 reactivity in a basal layerlike distribution, whereas undifferentiated cells of grade III SCCs showed ππto πππ positivity. A grade IV spindle SCC showed π immunoreactivity. The SCCs in situ showed remarkable expression of p63 in all cell layers. Terminally differentiated squamous cells were either negative or showed only focal immunoreactivity in the carcinomas. Conclusions: p63 is consistently expressed in the basal cells of epidermis and cutaneous appendages, including the basal/ myoepithelial cells of sweat glands. Based on our findings, the balance of probabilities favors that p63 might play a role in the pattern of differentiation and in the oncogenesis of usual carcinomas of the skin.Fundação para a Ciência e a Tecnologia (FCT) - SFRH/BD/5386/2001. Fundação para a Ciência e a Tecnologia (FCT) – Programa Operacional “Ciência, Tecnologia, Inovação” (POCTI)

Optimising calcium phosphate cement formulations to widen clinical applications

The demand for reconstructive orthopaedic implants continues expanding at a reasonable pace as the incidence of fracture injuries and infectious diseases rises. There has been an increase in the clinical need for more effective synthetic bone graft materials due to the drawbacks of autogenous grafts. Since the 1980’s calcium phosphate cements (CPC’s) have attracted a great deal of interest due to their chemical similarities to natural bone; chemical, physical and mechanical characteristics have been investigated and manipulated to maximise osteoconductivity and osteointegration of these CPC’s since the start of their commercialisation. Here in this thesis, a series of investigation are complied to demonstrate novel and inventive approaches to expand the application of CPC’s: (1) limiting the liquid phase in the setting reaction of a brushite cement to produce monetite (dehydrated brushite) based cement, with increased solubility to overcome the problems faced by long term stability of hydroxyapatite (HA) cements; (2) manipulating the cement formulation to produce a cement that can set on a change in temperature, upon implantation, increasing handling time during surgeries; (3) incorporating therapeutic molecules to eliminate secondary surgeries following infectious diseases; (4) to enhance osteointegration of CPC’s by synchronising the degradation to natural bone formation. Results exhibit compressive strength appropriate for the application of cranioplasty; long term ageing studies demonstrates that the novel cement formulations do not hydrolyse to HA, eliminating the risk of catastrophic brittle failure that is commonly associated with CPC’s.EThOS - Electronic Theses Online ServiceGBUnited Kingdo