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| 2. |
- Mangano, M. C., et al.
(författare)
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The aquaculture supply chain in the time of covid-19 pandemic : Vulnerability, resilience, solutions and priorities at the global scale
- 2022
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Ingår i: Environmental Science and Policy. - : Elsevier. - 1462-9011 .- 1873-6416. ; 127, s. 98-110
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Tidskriftsartikel (refereegranskat)abstract
- The COVID-19 global pandemic has had severe, unpredictable and synchronous impacts on all levels of perishable food supply chains (PFSC), across multiple sectors and spatial scales. Aquaculture plays a vital and rapidly expanding role in food security, in some cases overtaking wild caught fisheries in the production of high quality animal protein in this PFSC. We performed a rapid global assessment to evaluate the effects of the COVID19 pandemic and related emerging control measures on the aquaculture supply chain. Socio-economic effects of the pandemic were analysed by surveying the perceptions of stakeholders, who were asked to describe potential supply-side disruption, vulnerabilities and resilience patterns along the production pipeline with four main supply chain components: a) hatchery, b) production/processing, c) distribution/logistics and d) market. We also assessed different farming strategies, comparing land-vs. sea-based systems; extensive vs. intensive methods; and with and without integrated multi-trophic aquaculture, IMTA. In addition to evaluating levels and sources of economic distress, interviewees were asked to identify mitigation solutions adopted at local / internal (i.e., farm site) scales, and to express their preference on national / external scale mitigation measures among a set of a priori options. Survey responses identified the potential causes of disruption, ripple effects, sources of food insecurity, and socio-economic conflicts. They also pointed to various levels of mitigation strategies. The collated evidence represents a first baseline useful to address future disaster-driven responses, to reinforce the resilience of the sector and to facilitate the design reconstruction plans and mitigation measures, such as financial aid strategies.
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| 3. |
- Sarà, G., et al.
(författare)
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The Synergistic Impacts of Anthropogenic Stressors and COVID-19 on Aquaculture : A Current Global Perspective
- 2022
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Ingår i: Reviews in Fisheries Science & Aquaculture. - : Informa UK Limited. - 2330-8249 .- 2330-8257. ; 30:1, s. 123-135
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Tidskriftsartikel (refereegranskat)abstract
- The rapid, global spread of COVID-19, and the measures intended to limit or slow its propagation, are having major impacts on diverse sectors of society. Notably, these impacts are occurring in the context of other anthropogenic-driven threats including global climate change. Both anthropogenic stressors and the COVID-19 pandemic represent significant economic challenges to aquaculture systems across the globe, threatening the supply chain of one of the most important sources of animal protein, with potential disproportionate impacts on vulnerable communities. A web survey was conducted in 47 countries in the midst of the COVID-19 pandemic to assess how aquaculture activities have been affected by the pandemic, and to explore how these impacts compare to those from climate change. A positive correlation between the effects of the two categories of drivers was detected, but analysis suggests that the pandemic and the anthropogenic stressors affect different parts of the supply chain. The immediate measurable reported losses varied with aquaculture typology (land vs. marine, and intensive vs. extensive). A comparably lower impact on farmers reporting the use of integrated multitrophic aquaculture (IMTA) methods suggests that IMTA might enhance resilience to multiple stressors by providing different market options under the COVID-19 pandemic. Results emphasize the importance of assessing detrimental effects of COVID-19 under a multiple stressor lens, focusing on areas that have already locally experienced economic loss due to anthropogenic stressors in the last decade. Holistic policies that simultaneously address other ongoing anthropogenic stressors, rather than focusing solely on the acute impacts of COVID-19, are needed to maximize the long-term resilience of the aquaculture sector.
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| 4. |
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The Seventeenth Data Release of the Sloan Digital Sky Surveys : Complete Release of MaNGA, MaStar, and APOGEE-2 Data
- 2022
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Ingår i: Astrophysical Journal Supplement Series. - : Institute of Physics (IOP). - 0067-0049 .- 1538-4365. ; 259:2
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Tidskriftsartikel (refereegranskat)abstract
- This paper documents the seventeenth data release (DR17) from the Sloan Digital Sky Surveys; the fifth and final release from the fourth phase (SDSS-IV). DR17 contains the complete release of the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey, which reached its goal of surveying over 10,000 nearby galaxies. The complete release of the MaNGA Stellar Library accompanies this data, providing observations of almost 30,000 stars through the MaNGA instrument during bright time. DR17 also contains the complete release of the Apache Point Observatory Galactic Evolution Experiment 2 survey that publicly releases infrared spectra of over 650,000 stars. The main sample from the Extended Baryon Oscillation Spectroscopic Survey (eBOSS), as well as the subsurvey Time Domain Spectroscopic Survey data were fully released in DR16. New single-fiber optical spectroscopy released in DR17 is from the SPectroscipic IDentification of ERosita Survey subsurvey and the eBOSS-RM program. Along with the primary data sets, DR17 includes 25 new or updated value-added catalogs. This paper concludes the release of SDSS-IV survey data. SDSS continues into its fifth phase with observations already underway for the Milky Way Mapper, Local Volume Mapper, and Black Hole Mapper surveys.
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| 5. |
- Buffolo, M., et al.
(författare)
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Modeling of the Optical and Electrical Degradation of 845 nm VCSILs
- 2023
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Ingår i: 2023 Conference on Lasers and Electro-Optics, CLEO 2023.
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Konferensbidrag (refereegranskat)abstract
- Optical and electrical degradation of novel micro-transfer-printed VCSILs is investigated. Modeling of experimental data suggests that the main degradation mechanism is represented by the relocation of impurities, originating from the p-side, toward the active region.
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| 6. |
- Zenari, M., et al.
(författare)
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Analysis of defect-related optical degradation of VCSILs for photonic integrated circuits
- 2023
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Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. ; 12439
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Konferensbidrag (refereegranskat)abstract
- Laser diodes are of paramount importance for on-chip telecommunications applications, and a wide range of sensing devices that require near-infrared sources. In this work, the devices under test are vertical-cavity silicon-integrated lasers (VCSILs) designed for operation at 845 nm in photonic integrated circuits (PICs). We focus on the analysis of the degradation of the optical performance during aging. To investigate the reliability of the devices, we carried out several stress tests at constant current, ranging from 3.5 mA to 4.5 mA representing a highly accelerated stress condition. We observed two different degradation modes. In the first part of the experiments, the samples exhibited a worsening of the threshold current, but the sub-threshold emission was unaffected by degradation. We associated this behavior to the diffusion of impurities that, from the p-contact, were crossing the upper mirror implying a worsening of the DBR optical absorption. In the second stage of the stress test, the devices showed a higher degradation rate of the threshold current, whose variation was found to be linearly correlated to the worsening of the sub-threshold emission. We related this second degradation mode to the migration of the same impurities degrading the top DBR that, when reaching the active region of the laser, induced an increase in the non-radiative recombination rate. In addition to that, we related the two degradation modes to the change in series resistance, which was ascribed to the resistivity increment of the top DBR first and of oxide aperture afterwards.
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| 7. |
- Zenari, M., et al.
(författare)
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Understanding the optical degradation of 845nm micro-transfer-printed VCSILs for photonic integrated circuits
- 2023
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Ingår i: IEEE Journal of Quantum Electronics. - 0018-9197 .- 1558-1713. ; 59:4
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Tidskriftsartikel (refereegranskat)abstract
- For the first time we investigate the optical degradation of vertical-cavity silicon-integrated lasers (VCSILs) designed for operation at 845 nm in photonic integrated circuits (PICs). The study is based on the combined electro-optical characterization of VCSIL, submitted to constant-current stress tests at different current levels. The original results obtained within the manuscript indicate that degradation is related to the diffusion of impurities. Remarkably, depending on the region through which these impurities are migrating, the diffusion process affects device characteristics in different ways. During Phase 1 (Ph1), compensating impurities originating from the metal-semiconductor contact cross the top DBR, thus degrading mirror reflectivity, which is rarely observed in the literature, and leading to an increase in the threshold current of the device. As the impurities start reaching the active region we observe the onset of Phase 2 (Ph2), during which both threshold current and sub-threshold slope worsen, due to the increase of the Shockley-Read-Hall recombination rate. This phase is also characterized by a measurable increase in series resistance, which is ascribed to a change in the resistance of the oxide aperture. The identification of the root cause of physical degradation represents a fundamental step for future lifetime improvement of these novel optical sources, which are set to replace conventional solid-state sources in the 0.85 μm communication window.
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| 8. |
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| 9. |
- Zenari, M., et al.
(författare)
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Addressing the electrical degradation of 845 nm micro-transfer printed VCSILs through TCAD simulations
- 2023
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Ingår i: Proceedings of the International Conference on Numerical Simulation of Optoelectronic Devices, NUSOD. - 2158-3234. ; 2023-September, s. 91-92
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Konferensbidrag (refereegranskat)abstract
- In this work we present the electrical modeling of novel 845 nm vertical-cavity silicon-integrated lasers (VCSILs) for silicon photonics (SiPh). We tested the reliability of the devices by submitting them to high current stress, corresponding to ≈ 20xIth, to observe the degradation as a function of time. During the stress experiment, we monitored the electrical characteristics at regular intervals and we observed two separate degradation phenomena: the series resistance increment and the lowering of the turn-on voltage. Thanks to a Poisson-drift diffusion simulator we simulated the I-V characteristics and the band diagrams to interpret the degradation phenomena. The results of the simulations confirmed that the electrical degradation can be caused by the diffusion of compensation impurities originating from the p-contact layers. The same mechanism was also responsible of the optical degradation of the devices.
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| 10. |
- Zenari, M., et al.
(författare)
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Impact of the oxide aperture width on the degradation of 845 nm VCSELs for silicon photonics
- 2024
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Ingår i: IEEE Journal of Selected Topics in Quantum Electronics. - 1558-4542 .- 1077-260X. ; In Press
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Tidskriftsartikel (refereegranskat)abstract
- For the first time, we analyzed the degradation as a function of the oxide aperture in 845 nm VCSELs designed for silicon photonics (SiPh) applications. First, we evaluated the optical degradation of the devices by collecting EL images during a constant current stress. The experimental results showed an increased spreading of the optical beam of the VCSEL with increasing ageing time. Based on numerical simulations, we demonstrated that the electrical degradation (increase in series resistance) is responsible a larger current spreading which, in turn, increases the FWHM (full width half maximum) of the optical beam. We further evaluated the series resistance variation by aging four lasers with different oxide apertures. The results of this set of experiments showed that the electrical degradation is stronger as the oxide aperture is smaller, and mostly depends on the contribution of the top DBR resistance. Thanks to our analysis we proved that the use of a larger aperture can result in a better device reliability.
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