Engineering neuronal networks with nanomaterials: graphene shaping of synaptic activity

Graphene is a single atomic plane material consisting of sp2 -hybridized carbon atoms with a hexagonal structural organization and characterized by unique properties such as high electrical conductivity, mechanical flexibility and optical transparency. Due to their peculiar features, graphene and its derivates have attracted an increasing interest for biomedical applications including drug and gene delivery, imaging and diagnostic or tissue engineering. However, using graphene-based nanomaterials (GBNs) in modern medicine, in particular neurology, needs a greater and deeper understanding of the cell-nanomaterial interactions. In this framework we focus on studying the impact of GBNs on the neuronal network and their ability in shaping synaptic transmission. First, we exploited 3D elastomeric scaffolds enriched with graphene to better understand the effects of this nanomaterial on the neural activity when interfacing neurons and synapses in the third dimension. Our results, using imaging techniques, show the ability of graphene to modulate the neuronal network formation in a 3D environment which might be due to modulations in the excitatory/inhibitory ratio. Afterwards we investigated the interactions between graphene oxide flakes with small lateral size (s-GO) and isolated amygdala neurons and synapses. Thus, we developed and characterized an in vitro model of amygdala network using immunofluorescence and electrophysiological techniques. When we acutely applied s-GO to these cultures, the nanomaterial was capable to selectively alter the glutamatergic excitatory activity. This peculiar interaction may be taken into account for exploiting s-GO as a novel tool to target central nervous system (CNS) synapses

Quadratic Hedging and Optimization of Option Exercise Policies in Incomplete Markets and Discrete Time

This paper extends quadratic hedging from European to Bermudan options in discrete time when markets are incomplete and investigates its use for supporting exercise policy optimization. The key idea is to construct date specific approximate replicating portfolios. Hedging any given exercise policy can be done by solving a collection of stochastic dynamic programs. Optimizing the exercise policy based on the resulting martingale measure requires care. If this measure is risk neutral (RN), the value of an optimal such policy, which can be obtained by augmenting the hedging model with an exercise policy optimization step, is a no arbitrage one. Otherwise this approach must be refined by imposing time consistency on exercise policies, although the value of the resulting exercise policy may not be arbitrage free. Following the common pragmatic strategy of specifying quadratic hedging under an RN measure, e.g., one calibrated to market prices, avoids these issues. In particular, it provides a simple hedging policy with immediate practical applicability and is equivalent to exercise policy optimization under RN valuation, thus complementing it with a consistent hedging policy. A simple numerical example shows that this procedure generates effective hedging policies

Ensayo-reseña

Álvaro Cepeda Samudio, Obra Literaria, Edición crítica de Fabio Rodríguez Amaya y Jacques Gilard. Poitiers/Medellín: CRLA-Sílaba, 2017, 734 pp. Colección Archivos vol. 6

Reinventare la finzione: Lejos de Roma di Pablo Montoya

Reinventare la finzione: Lejos de Roma di Pablo Montoya (Bogotá, Alfaguara, 2008, 178 pp. ISBN 978-958-704-694-6) di Alessandro Secomand

Pandemic knowledge and regulation effectiveness: Evidence from COVID-19

The spread of COVID-19 led countries around the world to adopt lockdown measures of varying stringency, with the purpose of restricting the movement of people. However, the effectiveness of these measures on mobility has been markedly different. Employing a difference-in-differences design, we analyse the effectiveness of movement restrictions across different countries. We disentangle the role of regulation (stringency measures) from the role of people's knowledge about the spread of COVID-19. We proxy COVID-19 knowledge by using Google Trends data on the term “Covid”. We find that lockdown measures have a higher impact on mobility the more people learn about COVID-19. This finding is driven by countries with low levels of trust in institutions and low levels of education

Magnetic signature of submarine volcanoes in the Phlegrean Fields-Ischia Ridge (North-Western side of the Bay of Naples, Southern Italy)

This paper presents a study of the Phlegrean Fields-Ischia submarine ridge by the analysis and interpretation of high-resolution aeromagnetic data recently acquired in the Western Procida offshore. The investigated area is located along the ridge connecting Ischia to the Phlegrean Fields and is characterized by the existence of several monogenetic volcanoes aligned on a NE-SW system of faults. The high-resolution magnetic data yielded new information on the area, highlighting particularly the signature of a volcanic body located between Pt. Serra and the Ruommoli shoal. This structure has not been clearly described before and we named it as the Pt. Serra submarine volcano. The computation of the analytic signal and horizontal gradient of the data distinctly located this structure and definined the position of its rims. A 2D modeling and 3D inversion of data provided information on the volcano’s thickness, width and magnetization, disclosing a meaningful igneous body extending down to several hundred meters b.s.l

O ARTEFATO IRREDUTÍVEL

The ideal of transparency in interface design is questioned on basis of postphenomenological studies in the field of philosophy of technology. It is argued that technologies establish several types of user relations, without ever becoming completely transparent to human experience. A study of the iPhone gives the analysis empirical suport.O ideal da transparência no design de interfaces é questionado com base em estudos pós-fenomenológicos no campo da filosofia da tecnologia. Argumenta-se que tecnologias estabelecem diversos tipos de relação com usuários sem nunca se tornarem completamente transparente à experiência humana. Um estudo do iPhone dá suporte empírico à análise

Erminio Corti, I manifesti delle avanguardie artistiche latinoamericane (1920-1935)

Erminio Corti, I manifesti delle avanguardie artistiche latinoamericane (1920-1935)(Verona, Ombre Corte, 2018, 266 pp. ISBN 978-88-6948-111-6) di Alessandro Secomand

The role of cellular senescence in female reproductive aging and the potential for senotherapeutic interventions

BACKGROUND: Advanced maternal age is associated with decreased oocyte quantity and quality as well as uterine and placental dysfunctions. These changes lead to infertility, pregnancy complications and birth defects in the offspring. As the mean age of giving birth is increasing worldwide, prevention of age-associated infertility and pregnancy complications, along with the more frequent use of ART, become extremely important. Currently, significant research is being conducted to unravel the mechanisms underlying female reproductive aging. Among the potential mechanisms involved, recent evidence has suggested a contributing role for cellular senescence, a cellular state of irreversible growth arrest characterized by a hypersecretory and pro-inflammatory phenotype. Elucidating the role of senescence in female reproductive aging holds the potential for developing novel and less invasive therapeutic measures to prevent or even reverse female reproductive aging and increase offspring wellbeing. OBJECTIVE AND RATIONALE: The review will summarize the positive and negative implications of cellular senescence in the pathophysiology of the female reproductive organs during aging and critically explore the use of novel senotherapeutics aiming to reverse and/or eliminate their detrimental effects. The focus will be on major senescence mechanisms of the ovaries, the uterus, and the placenta, as well as the potential and risks of using senotherapies that have been discovered in recent years. SEARCH METHODS: Data for this review were identified by searches of MEDLINE, PubMed and Google Scholar. References from relevant articles using the search terms ‘Cellular Senescence’, ‘Aging’, ‘Gestational age’, ‘Maternal Age’, ‘Anti-aging’, ‘Uterus’, ‘Pregnancy’, ‘Fertility’, ‘Infertility’, ‘Reproduction’, ‘Implant’, ‘Senolytic’, ‘Senostatic’, ‘Senotherapy’ and ‘Senotherapeutic’ where selected. A total of 182 articles published in English between 2005 and 2020 were included, 27 of which focus on potential senotherapies for reproductive aging. Exclusion criteria were inclusion of the terms ‘male’ and ‘plants’. OUTCOMES: Aging is a major determinant of reproductive wellbeing. Cellular senescence is a basic aging mechanism, which can be exploited for therapeutic interventions. Within the last decade, several new strategies for the development and repurposing of drugs targeting senescent cells have emerged, such as modulators of the anti-inflammatory response, oxidative stress, DNA damage, and mitochondria and protein dysfunctions. Several studies of female reproductive aging and senotherapies have been discussed that show promising results for future interventions. WIDER IMPLICATIONS: In most countries of the Organization for Economic Co-operation and Development, the average age at which women give birth is above 30 years. Currently, in countries such as the Netherlands, Australia, Spain, Finland, Germany and the UK, birth rates among 30- to 34-year-olds are now higher than in any other age groups. This review will provide new knowledge and scientific advancement on the senescence mechanisms during female reproductive aging, and benefit fundamental and clinical scientists and professionals in the areas of reproduction, cancer, immunobiology and fibrosis