The Mediterranean Sea Regime Shift at the End of the 1980s, and Intriguing Parallelisms with Other European Basins

Background: Regime shifts are abrupt changes encompassing a multitude of physical properties and ecosystem variables, which lead to new regime conditions. Recent investigations focus on the changes in ecosystem diversity and functioning associated to such shifts. Of particular interest, because of the implication on climate drivers, are shifts that occur synchronously in separated basins. Principal Findings: In this work we analyze and review long-term records of Mediterranean ecological and hydro-climate variables and find that all point to a synchronous change in the late 1980s. A quantitative synthesis of the literature (including observed oceanic data, models and satellite analyses) shows that these years mark a major change in Mediterranean hydrographic properties, surface circulation, and deep water convection (the Eastern Mediterranean Transient). We provide novel analyses that link local, regional and basin scale hydrological properties with two major indicators of large scale climate, the North Atlantic Oscillation index and the Northern Hemisphere Temperature index, suggesting that the Mediterranean shift is part of a large scale change in the Northern Hemisphere. We provide a simplified scheme of the different effects of climate vs. temperature on pelagic ecosystems. Conclusions: Our results show that the Mediterranean Sea underwent a major change at the end of the 1980s that encompassed atmospheric, hydrological, and ecological systems, for which it can be considered a regime shift. We further provide evidence that the local hydrography is linked to the larger scale, northern hemisphere climate. These results suggest that the shifts that affected the North, Baltic, Black and Mediterranean (this work) Seas at the end of the 1980s, that have been so far only partly associated, are likely linked as part a northern hemisphere change. These findings bear wide implications for the development of climate change scenarios, as synchronous shifts may provide the key for distinguishing local (i.e., basin) anthropogenic drivers, such as eutrophication or fishing, from larger scale (hemispheric) climate drivers

Re-cycling paradigms: cell cycle regulation in adult hippocampal neurogenesis and implications for depression

Since adult neurogenesis became a widely accepted phenomenon, much effort has been put in trying to understand the mechanisms involved in its regulation. In addition, the pathophysiology of several neuropsychiatric disorders, such as depression, has been associated with imbalances in adult hippocampal neurogenesis. These imbalances may ultimately reflect alterations at the cell cycle level, as a common mechanism through which intrinsic and extrinsic stimuli interact with the neurogenic niche properties. Thus, the comprehension of these regulatory mechanisms has become of major importance to disclose novel therapeutic targets. In this review, we first present a comprehensive view on the cell cycle components and mechanisms that were identified in the context of the homeostatic adult hippocampal neurogenic niche. Then, we focus on recent work regarding the cell cycle changes and signaling pathways that are responsible for the neurogenesis imbalances observed in neuropathological conditions, with a particular emphasis on depression

Achievement of Graded Band Gap in CdTe Solar Cells through Selenization of the Absorber

The awareness of climate change is growing worldwide and with it, also the request for alternative energy solutions to fossil sources. Photovoltaic energy is one of the main answers, since the technology is well developed and can be installed anywhere. The main challenge in this field, today, is to reduce the costs of the energy produced. In this respect, CdTe thin film panels, which can be fabricated in a single manufacturing line, have a great advantage over traditional crystalline silicon cells. Moreover their efficiency is nowadays closer to that of silicon cells, having reached a value of 22.1 %. The efficiency improvement is mainly due to the replacement of the CdS layer with MZO, which has a higher band gap, and to the introduction of a CdTe1-xSex layer, which allows the grading of the absorber band gap, increasing the absorption in the long wavelength region. In this work we present a novel method to produce the band gap grading of the CdTe absorber layer through selenization of the CdTe layer

Effects of Ultra-Thin Copper Layer on the Performance and Stability of CdTe/CdS Solar Cells

CdTe solar cells have shown high efficiency well above 20%. Despite different copper-free back contacts have been successfully introduced this is still required for very high efficiency devices. On the other hand an excessive amount of copper results in degradation of the device and a suitable concentration is very important for a good trade off between conversion efficiency and stability. A study on how the amount of copper at the back contact affects the performances and the stability of CdTe thin film solar cells is presented. CdTe cells with 0.1 nm Cu layer are compared to devices with 2 nm Cu and the electrical properties are measured. The formation of Cu-Te compounds has been analysed and degradation of cells made with thick and thin Cu layer has been recorded. With different copper thicknesses, different approaches are needed for high efficiencies; moreover devices degrade with different mechanisms

Low Temperature Co-Selenised Antimony Selenide (Sb2Se3) Based Solar Cells by Vacuum Evaporation

In this work, we study an alternative path for Sb2Se3 preparation by thermal evaporation for low temperature substrate deposition. Thermal evaporation delivered, up to now, lower efficiency devices compared to close space sublimation based solar cells. One of the drawbacks of thermal evaporation for Sb2Se3 is the re-evaporation of Se on the substrate, for this reason we present an alternative route to adjust the stoichiometry of selenium deficient Sb2Se3 films by adding an excess of selenium (Se) for the deposition of 800 nm thin film by co-evaporation of Se and Sb2Se3. Thin films were deposited on Glass/FTO/SnO2/CdS substrate and their structural and electrical properties have been studied, together with the analysis of the finished devices