813 research outputs found
On the formation and features of the supra-wavelength grooves generated during femtosecond laser surface structuring of silicon
No full textWe have investigated the formation process of supra-wavelength quasi-periodic surface structures, commonly termed as grooves, produced during femtosecond laser surface structuring of a silicon target, in air. The experiments have been carried out at two wavelengths, namely 513 nm and 1026 nm, and in multi-pulse irradiation conditions. Both static, i.e., irradiating the same target location, and dynamic, namely scanning the beam along a line, configurations have been explored. We have also carried out simulations of the process by using a multiscale numerical model, based on the two-temperature model coupled to a fluid dynamics approach. The comparison of experimental and numerical results has allowed us to clearly establish the role of hydrothermal waves in the grooves formation process
Altered amygdala and hippocampus function in adolescents with hypercortisolemia: A functional magnetic resonance imaging study of Cushing syndrome
No full textChronic elevations of endogenous cortisol levels have been shown to alter medial temporal cortical structures and to be accompanied by declarative memory impairments and depressive symptoms in human adults. These effects of elevated endogenous levels of cortisol have not been directly studied in adolescents. Because adolescents with Cushing syndrome show endogenous elevations in cortisol, they represent a unique natural model to study the effects of prolonged hypercortisolemia on brain function, and memory and affective processes during this developmental stage. Using functional magnetic resonance imaging (fMRI), we compared 12 adolescents with Cushing syndrome with 22 healthy control adolescents on amygdala and anterior hippocampus activation during an emotional faces encoding task. None of these adolescents manifested depressive symptoms. Encoding success was assessed using a memory recognition test performed after the scan. The fMRI analyses followed an event-related design and were conducted using the SPM99 platform. Compared to healthy adolescents, patients with Cushing syndrome showed greater left amygdala and right anterior hippocampus activation during successful face encoding. Memory performance for faces recognition did not differ between groups. This first study of cerebral function in adolescents with chronic endogenous hypercortisolemia due to Cushing syndrome demonstrates the presence of functional alterations in amygdala and hippocampus, which are not associated with affective or memory impairments. Such findings need to be followed by work examining the role of age and related brain maturational stage on these effects, as well as the identification of possible protective factors conferring resilience to affective and cognitive consequences in this disease and/or during this stage of cerebral development
Application of differential analysis of VLF signals for seismic-ionospheric precursor detection from multiple receivers
No full textPlasmonic bulk heterojunction solar cells: the role of nanoparticle ligand coating
No full textThere has been a lot of interest regarding the influence of active-layer-incorporated plasmonic nanoparticles (NPs) in the performance of bulk heterojunction organic photovoltaic (OPV) devices, while both an increase and decrease in performance have been reported. In this paper, following a systematic approach, we demonstrate strong evidence of the critical importance of the NPs’ ligand shell on the device performance. In particular, it is argued that the plasmonic effect accountable for the performance enhancement takes place only in the case in which the NP’s core is in direct contact with the active layer polymer donor. This can be achieved with the utilization of either ligand-free NPs or NPs terminated with the same polymer donor as the active layer. Using this concept we achieved an enhanced efficiency of 7.16% in OPV devices incorporating the poly(3-hexylthiophene-2,5-diyl) (P3HT):indene-C60 bisadduct (ICBA) active layer. On the contrary, devices with ligand-terminated Au NPs show lower performance, even compared with the reference, NP-free, device due to the deteriorated active layer morphology attained, which leads to exciton quenching. These new insights into the plasmonic light-harvesting technology could shed light on the existing controversy and provide guidelines for device design and fabrication
Aspects of Rural Development in Greece: Indicators, Policies and New Opportunities
No full textRural development has attracted the interest of European regional and agricultural policies in the last two decades. This is more evident after the late 1990’s when rural development became the second pillar of Common Agricultural Policy (CAP). In Greece, traditional agricultural programs have given their place to rural development programs. This shift of emphasis in European agricultural policy reflects the change in the way rural development is perceived at an international level. Rural development is no more synonymous to agricultural development and the role of other factors such as alternative employment opportunities and accessibility to urban centers is widely recognized. Greece has a large agricultural sector compared to the European average, although employment in the primary sector has decreased significantly in the last three decades. In terms of rural development great differences are observed among regions which can be attributed to differences in agricultural potential and accessibility to the markets as well as to a differentiated degree of incorporation to international markets. The prospects of the agricultural sector in Greece would not be considered as favorable, especially after the latest CAP reform. Therefore rural development has to be promoted through non-agricultural activities or through some innovative agricultural activities. In this paper a series of indices describing the agricultural potential in the NUTSIII regions in Greece as well as several aspects of rural development will be presented. Statistical analysis, mostly classification techniques, will be employed in order to explore the factors contributing to rural development in Greece. Special attention will be given to the introduction of organic farming in Greece and its potential contribution to rural development. Organic farming is considered as an innovative agricultural activity and it can be a viable alternative for declining rural regions. Finally, rural development policies in Greece, through regional policy programs and the current Rural Development Program, will be presented, with emphasis on the shift from measures for the agricultural sector to measures for rural development. Special consideration will be given to the measures addressed to organic farming and their effectiveness in the development of the sector will be discussed.
Aberrant DNA hypermethylation of SDHC: a novel mechanism of tumor development in Carney triad
No full textCarney triad (CT) is a rare condition with synchronous or metachronous occurrence of gastrointestinal stromal tumors (GISTs), paragangliomas (PGLs), and pulmonary chondromas in a patient. In contrast to Carney-Stratakis syndrome (CSS) and familial PGL syndromes, no germline or somatic mutations in the succinate dehydrogenase (SDH) complex subunits A, B, C, or D have been found in most tumors and/or patients with CT. Nonetheless, the tumors arising among patients with CT, CSS, or familial PGL share a similar morphology with loss of the SDHB subunit on the protein level. For the current study, we employed massive parallel bisulfite sequencing to evaluate DNA methylation patterns in CpG islands in proximity to the gene loci of all four SDH subunits. For the first time, we report on a recurrent aberrant dense DNA methylation at the gene locus of SDHC in tumors of patients with CT, which was not present in tumors of patients with CSS or PGL, or in sporadic GISTs with KIT mutations. This DNA methylation pattern was correlated to a reduced mRNA expression of SDHC, and concurrent loss of the SDHC subunit on the protein level. Collectively, these data suggest epigenetic inactivation of the SDHC gene locus with functional impairment of the SDH complex as a plausible alternate mechanism tumorigenesis in CT
A multiple receiver - multiple transmitter VLF high-order differential analysis evaluation network for near real-time detection and discrimination of seismic-ionospheric precursor phenomena
No full textIncident angle influence on ripples and grooves produced by femtosecond laser irradiation of silicon
No full textWe report an experimental investigation on laser induced periodic surface structures formed on crystalline silicon at various angle of incidence θ, for p-polarization in air. The features of ripples and grooves formed in the shallow craters were analyzed for two different laser wavelengths λ (1026 nm and 513 nm). The period of the ripples displays the expected angular dependence for p-polarized light irradiation with the two different branches Λ±=λ/Reη∓sinθ, where η is the effective refractive index of the air-target interface. Instead, the grooves period shows a decreasing angular dependence well-described by a cosθ function. In addition, very regular ripples with subwavelength periodicity Λ− are formed at some characteristic angles for which the expected period Λ+ is very close to an integer multiple of Λ−. Simulations of the process at various angles were also carried out by using a multiscale numerical model in which the enhanced contribution of hydrodynamical effects were highlighted. The simulations predict angular dependencies of the surface structures period qualitatively similar to the ones observed in the experiments clearly supporting the influence of hydrothermal waves in grooves formation process
SMART SUSTAINABLE ISLANDS VS SMART SUSTAINABLE CITIES
No full textThis paper has several aims: a) the presentation of a critical analysis of the terms “smart sustainable cities” and “smart sustainable islands” b) the presentation of a number of principles towards to the development methodological framework of concepts and actions, in a form of a manual and actions guide, for the smartification and sustainability of islands. This kind of master plan is divided in thematic sectors (key factors) which concern the insular municipalities c) the creation of an island’s smartification and sustainability index d) the first steps towards the creation of a portal for the presentation of our smartification actions manual, together with relative resources, smart applications examples, and, in the near future the first results of our index application in a number of Greek islands and e) the presentation of some proposals of possible actions towards their sustainable development and smartification for the municipalities - islands of Paros and Antiparos in Greece, as case studies
Possible pre-seismic radio anomalies observed on the occasion of the MW=5.9 and MW=6.5 earthquakes occurred in Central Italy at the end of October 2016
No full textOn October 26, 2016 an earthquake with Mw=5.9 occurred in Central Italy, near Castelsantangelo village; after 4
days the main shock with Mw=6.5 occurred near Norcia small town. The two epicenters are 12 km far from each
other and are located in the sensitive area of the European VLF/LF Radio Network (INFREP). Unfortunately, at the
time of the earthquake, several receivers were out of service, so only the data from Cyprus receiver are available.
Some days before the first earthquake two clear anomalies appeared one after the other in two of the ten signals,
the intensity of which is collected with 1 min sampling rate by this receiver. The two signals are radiated by DHO
transmitter (23.4 kHz) ) located in Rhauderfehn (Germany) and by ICV transmitter (20.27kHz) located in Sardinia
(Italy). The 5th Fresnel zones of the radio paths brush the border of the Dobrovolsky area of the previous main
shock. The anomalies seem to move in the same direction of the two epicenters. Here we present in detail the
anomalies and we discuss the possibility that they are precursors of the quoted earthquakes. As mentioned before,
we have no more data to examine in order to confirm and endorse these anomalies
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