278 research outputs found

    Assessment of Low Polarization Dependent Multicast and Select Switch Based on Bulk SOA for Data Center Application

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    We have designed, fabricated, and characterized a low polarization dependent multicast and select (MCS) switch based on a newly developed novel bulk SOA co-integrated with passive waveguides. The proposed new bulk SOA-based MCS switch requires the co-integration of active SOAs (gate and booster) with several passive InP elements. First, we have presented a theoretical analysis and the design and properties of the proposed bulk SOA and demonstrated its low polarization-dependent properties. Then, we evaluated and characterized the switch's performance, including gain, optical signal-to-noise ratio (OSNR), and data transmission features. The experimental results verify that the MCS switch exhibits polarization-dependent gain in the range of 0.1 to 2.2 dB for all ports and a broadband gain of approximately 70 nm across all ports. The measured OSNR, for all channels, is &gt; 42 dB at 1580 nm. Moreover, experimental data transmission assessments show operation at high bitrates of 30 Gb/s with a low power penalty of less than 1 dB at 10-9. The dynamic power penalty range of the switch is also investigated. The MCS switch exhibits a wide range of &gt; 20 dB input power dynamic range for a power penalty of less than 3 dB for a 10 Gb/s NRZ signal.</p

    Experimental Studies of Autonomous Sailing With a Radio Controlled Sailboat

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    Autonomous sailing has attracted many interests from both industry and academy due to its great potential in oceanography, research and education. Worldwide researchers have developed various kinds of unmanned sailboat platforms for their specific research purposes and applications. However, most of these autonomous sailing platforms are rather complex to build and to program. The aim of this study is to propose, to build, and to test a new compact sailboat platform using a unique combination of a 1-m class radio controlled model sailboat, a Raspberry Pi 4, a Navio2, and a Calypso ultrasonic solar-powered anemometer. The proposed new sailboat platform makes full use of the agility of the racing model boat with minimal mechanical adjustments as the system does not use electrical wires to connect with additional sensors and a mechanical anemometer. The software architecture of the proposed new sailboat platform is also simplified as it involves only Python programming for the Raspberry Pi 4. The experimental results have demonstrated the feasibility as well as the functionality of the proposed new sailboat platform to conduct autonomous sailing operations successfully and it could become one of the most accessible, generic and flexible autonomous sailing platforms for advanced research and education in robotics, autonomous systems, and artificial intelligence

    Integrated optical phased array with on-chip amplification enabling programmable beam shaping

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    We present an integrated optical phased array (OPA) which embeds in-line optical amplifiers and phase modulators to provide beam-forming capability with gain and beam steering in the 1465–1590 nm wavelength range. We demonstrate up to 21.5 dB net on-chip gain and up to 35.5 mW optical output power. The OPA circuit is based on an InP photonic integration platform and features the highest measured on-chip gain and output power level recorded in an active OPA (i.e., with amplification), to the best of our knowledge. Furthermore, the OPA enables the independent control of both amplitude and phase in its arms and through this we demonstrate programmable beam shaping for two cases. First, we carried out a Gaussian apodization of the power distribution profile in the OPA emitter waveguides, leading to 19.8 dB sidelobe suppression in the far-field beam, which is the highest value recorded for active OPAs, and then we demonstrated beam forming of 0th, 1st, and 2nd order 1D Hermite–Gaussian beams in free-space

    Quasi-linear Masking to Protect Kyber against both SCA and FIA

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    The recent technological advances in Post-Quantum Cryptography (PQC) rise the questions of robust implementations of new asymmetric cryptographic primitives in today’s technology. This is the case for the lattice-based CRYSTALS-Kyber algorithm which has been selected as the first NIST standard for Public Key Encryption (PKE) and Key Encapsulation Mechanisms (KEM). We have notably to make sure the Kyber implementation is resilient against physical attacks like Side-Channel Analysis (SCA) and Fault Injection Attacks (FIA). To reach this goal, we propose to use the masking countermeasure, more precisely the generic Direct Sum Masking method (DSM). By taking inspiration of a previous paper on AES, we extend the method to finite fields of characteristic prime other than 2 and even-length codes. In particular, we investigated its application to Keccak, which is the hash-based function used in Kyber. We also provided the first masked implementation of Kyber providing both SCA and FIA resilience while not requiring any conversion between different masking methods

    Developing policy-relevant biodiversity indicators : lessons learnt from case studies in Africa

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    There is an increasing need for monitoring schemes that help understand the evolution of the global biodiversity crisis and propose solutions for the future. Indicators, including temporal baselines, are crucial to measure the change in biodiversity over time, to evaluate progress towards its conservation and sustainable use and to set conservation priorities. They help design and monitor national and regional policies on biodiversity; they also feed into national reporting on international agreements such as the Convention on Biological Diversity and the Sustainable Development Goals. We analyse the methodological approach of five small African projects resulting from a call to promote indicator development, improve monitoring capacity and strengthen the science-policy interface in the field of biodiversity. We compared their approach to existing guidance provided by the international community, specifically the Biodiversity Indicators Partnership. To this end, we assess whether internationally recommended steps are effectively applied to national/local biodiversity monitoring in selected developing countries. We also present lessons learnt from workshop interactions between partners involved in these projects. Through our pilot projects we identified data availability and data accessibility, together with the involvement of stakeholders, as critical steps in indicator development. Moreover, there is a need for a better awareness and a wider application of the indicator concept itself. Hence, training of key actors both in the policy and science spheres is needed to operationalize indicators and ensure their continuity and sustainability. We hope that these case studies and lessons learnt can stimulate and support countries in the Global South to formulate policy-relevant biodiversity indicators.Peer reviewe

    Is Sensory Loss an Understudied Risk Factor for Frailty? A Systematic Review and Meta-analysis

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    [Abstract] Background. Age-related sensory loss and frailty are common conditions among older adults, but epidemiologic research on their possible links has been inconclusive. Clarifying this relationship is important because sensory loss may be a clinically relevant risk factor for frailty. Methods. In this systematic review and meta-analysis, we searched 3 databases for observational studies investigating 4 sensory impairments—vision (VI), hearing (HI), smell (SI), and taste (TI)—and their relationships with frailty. We meta-analyzed the cross-sectional associations of VI/HI each with pre-frailty and frailty, investigated sources of heterogeneity using meta-regression and subgroup analyses, and assessed publication bias using Egger’s test. Results. We included 17 cross-sectional and 7 longitudinal studies in our review (N = 34,085) from 766 records. Our cross-sectional meta-analyses found that HI and VI were, respectively, associated with 1.5- to 2-fold greater odds of pre-frailty and 2.5- to 3-fold greater odds of frailty. Our results remained largely unchanged after subgroup analyses and meta-regression, though the association between HI and pre-frailty was no longer significant in 2 subgroups which lacked sufficient studies. We did not detect publication bias. Longitudinal studies largely found positive associations between VI/HI and frailty progression from baseline robustness, though they were inconclusive about frailty progression from baseline pre-frailty. Sparse literature and heterogenous methods precluded meta-analyses and conclusions on the SI/TI–frailty relationships. Conclusions. Our meta-analyses demonstrate significant cross-sectional associations between VI/HI with pre-frailty and frailty. Our review also highlights knowledge gaps on the directionality and modifiability of these relationships and the impact of SI/TI and multiple sensory impairments on frailty

    A tectonic model for the juxtaposition of granulite- and amphibolite-facies rocks in the Eburnean orogenic belt (Sassandra-Cavally domain, Côte d’Ivoire)

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    The Sassandra-Cavally (SASCA) domain (SW Côte d’Ivoire) marks the transition between the Archean Kenema-Man craton and the Paleoproterozoic (Rhyacian) Baoule-Mossi domain. It is characterized by the tectonic juxtaposition of granulite-facies and amphibolite-facies rocks. Migmatitic grey gneisses, garnet–cordierite–sillimanite migmatitic paragneisses and garnet–staurolite-bearing micaschists reached peak pressure conditions ranging from ∼ 6.6 kbar at 620 °C to ∼ 10 kbar at 820 °C. These conditions are associated with the first recorded deformation D1 and correspond to a Barrovian geothermal gradient of ∼ 25 °C/km. Subsequent exhumation, associated with a second deformation D2, was marked by decompression followed by cooling along apparent geothermal gradients of ∼ 40 °C/km. A D3 deformation phase is marked by folding and local transposition of the regional S1/S2 foliation into E-W trending shear zones. LA-ICP-MS U–Pb dating of monazite, which displays complex internal structures, reveals four age groups correlated to textural position of monazite grains and analytical points: (1) rare relictual zones yield dates at the Archean-Paleoproterozoic transition (ca. 2400–2600 Ma); (2) a cluster of dates centered at ca. 2037 Ma on grains aligned along the S2 foliation of the migmatitic grey gneiss, attributed to D2; (3) a cluster of dates centered at ca. 2000 Ma, and (4) dates spreading from ca. 1978 to 1913 Ma, documented for the first time in the West African Craton monazites. The ages of the latter two groups are similar to the ones identified in the Guiana Shield, and could be attributed to a disturbance by fluids, to a periodic opening of U–Pb system or to an episodic crystallization of monazite during slow cooling lasting several tens of Myrs. These data allow to propose a model for the tectonic evolution of the SASCA domain at the contact between the Rhyacian Baoule-Mossi domain and the Archean Kenema-Man nucleus whereby crustal thickening is achieved by crustal-scale folding and is followed by and concomitant with lateral flow of the thickened partially molten crust accommodated by regional transcurrent shear zones. This combination of crustal thickening controlled by tectonic forces and gravity-driven flow leads to the juxtaposition of granulite- and amphibolite-facies rocks
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