Performance implications of three-mirror Fabry-Perot demultiplexers for 10-Gb/s WDM dispersion-supported transmission with 0.5-nm channel spacing

This letter assesses the performance of dispersion-supported transmission (DST) for three 10-Gb/s WDM channels separated 0.5 nm, using a three-mirror Fabry-Perot demultiplexer. It is shown that the use of three-mirror demultiplexers reduces the crosstalk penalty to less than 1 dB in the region of small linear increase of dispersion penalty of the DST method, while double-cavity Fabry-Perot demultiplexers are less suitable to operate at this channel spacing. Compared with published performance studies for WDM-DST systems with 1 nm of channel spacing, these results indicate the channel spacing may be cut in a half, if a three-mirror filter is used as demultiplexe

On the Performance of LDPC-Coded MIMO Schemes for Underwater Communications Using 5G-like Processing

UIDB/EEA/50008/2020This article studies the underwater acoustic (UWA) communications associated with multiple input–multiple output (MIMO), single carrier with frequency-domain equalization (SC-FDE), and with low-density parity-check (LDPC) codes. Low-complexity receivers such as equal gain combining (EGC), maximum ratio combining (MRC), and iterative block—decision feedback equalization (IB-DFE) are studied in the above-described scenarios. Furthermore, due to the low carrier frequencies utilized in UWA communications, the performance of the proposed MIMO scenarios is studied at different levels of channel correlation between antennas. This article shows that the combined schemes tend to achieve good performances while presenting low complexity, even in scenarios with channel correlation between antennas.publishersversionpublishe

The effect of a tangential frictional force on rotating disks: an experimental approach

This paper describes an experiment with two touching rotating disks, whose movement is followed by video analysis. Within the disks’ movements, there are intervals with sliding and intervals without sliding, that is, intervals with frictional forces between the touching surfaces and intervals without it. This system configuration allows for measurement of the changeable magnitudes and directions of frictional forces (much more difficult to set up with translational motion). This activity may be used to combat students misconceptions of “frictional force always opposes the motion” and “between the same two bodies, one gets the same frictional force,” commonly found in the classroom, or just to reinforce the rotational dynamics relationships

Parallel 3D limit analysis via the alternating direction method of multipliers

This document presents a parallelized implementation of a FEM formulation concerning both the upper and lower bound limit analysis theorems. By applying these methods to evaluate the stability of a vertical cut (i.e. vertical slope) in drained and undrained conditions, it is possible to discuss the efficiency of this strategy

Luria lurida (Gastropoda), a new record for the Pleistocene of Santa Maria, Azores

The cypraeid gastropod Luria lurida (Linnaeus, 1758) is reported for the first time from Pleistocene deposits at the Prainha site, on the island of Santa Maria, Azores archipelago

Specific warm-up exercise is the best for vertical countermovement jump in young volleyball players

We evaluated the effect of performing various distinct warm-up exercises on vertical countermovement jump (VCMJ) performance. Eight volleyball players (age 15.4 ± 0.5 yrs) performed five different warm-up activities (in a counterbalanced, randomized crossover study) over five days, at 24-h intervals: stretching (4 × 30 s, 30 s between sets), cycloergometer (5 min at 50 W + 5 min at 100 W), resistance exercise (leg press 45°, 3 × 5 repetitions maximum, 3-min pause between sets), specific vertical jumping (4 × 10 VCMJ, 2-min pause between sets), and no warm-up at all (control condition). Beginning 3 min after their warm-up, the players performed 3 attempts (at intervals of 3 min) of VCMJ (on a contact carpet), and each player's best jump was considered in the analysis. All warm-up activities presented higher VCMJ performance (p< 0.05) than the control condition, with the exception of stretching. Vertical jumping revealed a large effect size(0.8) than other interventions. We conclude that in practical terms, vertical jumps are the best warm-up exercise (when applied by itself) to acutely improve VCMJ performance in volleyball players, but that other exercises can make a complementary contribution.

Avaliação da qualidade de vida em doentes com insuficiência cardíaca submetidos a terapêutica com cardioversor desfibrilhador implantável

O cardioversor desfibrilhador implantável (CDI) tem sido associado à redução da morte súbita. O impacto nas dimensões da qualidade de vida (QV) permanece controverso. Método: 36 doentes foram submetidos a implantação de CDI. Foram avaliados antes da intervenção e após ao 3º e 6º mês pelo Kansas City Cardiomiophathy Questionnaire. Resultados: Os sintomas e conhecimento da situação clínica não se modificaram. Ao 3º mês, houve melhoria das actividades de vida diária, funcionalidade e QV, não mantida aos 6 meses. Aos 3º e 6º meses houve melhoria da percepção da satisfação com a vida e estilo de vida. A esperança associou-se à melhoria da percepção da satisfação com a vida. Conclusão: A implantação de CDI, associa-se a um benefício mantido na dimensão social e de percepção pessoal da QV e a um benefício transitório da condição física e percepção global da QV, sem influenciar os sintomas e conhecimento da condição clínica

Age of Information in a SWIPT and URLLC enabled Wireless Communications System

This paper estimates the freshness of the information in a wireless relay communication system that employs simultaneous wireless information and power transfer (SWIPT) operating under ultra-reliable low-latency communication (URLLC) constraints. The Age of Information (AoI) metric calculates the time difference between the current time and the timestamp of the most recent update received by the receiver is used here to estimate the freshness of information. The short packet communication scheme is used to fulfil the reliability and latency requirements of the proposed wireless network and its performance is analysed using finite block length theory. In addition, by utilising novel approximation approaches, expressions for the average AoI (AAoI) of the proposed system are derived. Finally, numerical analysis is used to evaluate and validate derived results

Tree canopy enhances Collembola functional richness and diversity across typical habitats of the Gorongosa National Park (Mozambique)

ABSTRACT: The role of tree canopies in protecting soil functional diversity is essential for ecosystems threatened by the longer lasting periods of drought, which are predicted to increase in the southern afro-tropical region. Nonetheless, biodiversity inventories of soil mesofauna are scarce in afro-tropical ecosystems, even in emblematic and well-studied protected areas, such as the Gorongosa National Park (GNP). Understanding the interrelationships between tree canopies and soil fauna functional diversity can provide insightful information for future adaptive management to protect wildlife and ecosystem services in the GNP, in the context of climate change. Here we assessed collembolan functional type richness and functional diversity in the dry period and during the rainfall across major GNP habitat types: miombo forests, mixed forests, and open savanna/floodplains. Besides the significant positive influence of rainfall, habitat types also influenced functional type’ richness and diversity of collembolan life-forms. Environmental gradients across habitat types, namely the area of tree canopy cover and its indirect effect on soil local conditions (pH and nutrient availability), explained collembolan functional parameters. Calcium concentrations and soil alkalinity significantly enhanced collembolan functional type richness and functional diversity, respectively. Collembola survival across GNP habitats depended on the canopy buffering in the dry sampling period. These results highlight the key role of tree canopies in creating suitable microhabitat conditions supporting soil functional diversity and the sustainability of soil processes and ecosystem services in GNP.info:eu-repo/semantics/publishedVersio

In situ growth of Ag nanoparticles on alpha-Ag2WO4 under electron irradiation: probing the physical principles

Exploiting the plasmonic behavior of Ag nanoparticles grown on α-Ag2WO4 is a widely employed strategy to produce efficient photocatalysts, ozone sensors, and bactericides. However, a description of the atomic and electronic structure of the semiconductor sites irradiated by electrons is still not available. Such a description is of great importance to understand the mechanisms underlying these physical processes and to improve the design of silver nanoparticles to enhance their activities. Motivated by this, we studied the growth of silver nanoparticles to investigate this novel class of phenomena using both transmission electron microscopy and field emission scanning electron microscopy. A theoretical framework based on density functional theory calculations (DFT), together with experimental analysis and measurements, were developed to examine the changes in the local geometrical and electronic structure of the materials. The physical principles for the formation of Ag nanoparticles on α-Ag2WO4 by electron beam irradiation are described. Quantum mechanical calculations based on DFT show that the (001) of α-Ag2WO4 displays Ag atoms with different coordination numbers. Some of them are able to diffuse out of the surface with a very low energy barrier (less than 0.1 eV), thus, initiating the growth of metallic Ag nanostructures and leaving Ag vacancies in the bulk material. These processes increase the structural disorder of α-Ag2WO4 as well as its electrical resistance as observed in the experimental measurements.The authors are grateful to Generalitat Valenciana (Spain) for PrometeoII/2014/022 and ACOMP/2014/270 projects, Ministerio de Economia y Competitividad (Spain), CTQ2012-36253-C03-02, and to the Spanish Brazilian Program (PHB2009-0065-PC), CAPES (203038 009607/2013- 56 088/2013), INCTMN (2008/57872-1), FAPESP (2013/ 07296-2; 2012/14468-1; 2010/16970-0) and CNPq (147001/2013-7; 573636/2008-7) for financially supporting this research. Most of the calculations were performed using IFGW-UNICAMP computer facilities and the National Center for High Performance Computing in São Paulo (CENAPAD- SP)