Lattice-Based proof of a shuffle

In this paper we present the first fully post-quantum proof of a shuffle for RLWE encryption schemes. Shuffles are commonly used to construct mixing networks (mix-nets), a key element to ensure anonymity in many applications such as electronic voting systems. They should preserve anonymity even against an attack using quantum computers in order to guarantee long-term privacy. The proof presented in this paper is built over RLWE commitments which are perfectly binding and computationally hiding under the RLWE assumption, thus achieving security in a post-quantum scenario. Furthermore we provide a new definition for a secure mixing node (mix-node) and prove that our construction satisfies this definition.Peer ReviewedPostprint (author's final draft

Alteração do comprimento do passo durante a transposição de obstáculos em tarefas de movimentação de cargas na construção civil

A Construção Civil tem sido o sector que regista maior incidência de acidentes fatais a nível mundial. Diversos estudos têm sido efectuados no sentido de compreender as causas que contribuem para a ocorrência de elevados índices de sinistralidade neste sector. Todavia, o contributo da movimentação manual de cargas, para a ocorrência de quedas na Construção Civil, tem sido descurado. No presente artigo procedeu-se, através de simulação laboratorial, ao estudo da influência da movimentação manual de cargas para a ocorrência de acidentes em operações envolvendo a transposição de obstáculos em obra. Verificou-se que o comprimento de passo e a passada do pé de avanço são alterados com o transporte de carga, aumentando a probabilidade de ocorrência de acidentes envolvendo quedas

Electrocatalytic performance and stability of nanostructured Fe–Ni pyrite-type diphosphide catalyst supported on carbon paper

A simple and effective method to prepare an active and stable nanostructured working electrode for electrochemical water splitting is described. Specifically, mixed Fe–Ni diphosphide was prepared by sputtering a 200-nm-thick layer of Permalloy onto carbon paper gas diffusion layer followed by gas transport phosphorization reaction. The mass density of the resultant diphosphide phase was established to be 1.1 mg/cm2. Energy-dispersive X-ray microanalysis shows that the actual elemental composition of the resultant ternary electrocatalyst is approximately Fe0.2Ni0.8P2, while the powder X-ray diffraction analysis confirms that the electrocatalyst crystallizes in NiP2 cubic pyrite-like structure. As a cathode for hydrogen evolution reaction (HER) in acidic and alkaline electrolytes, this earth-abundant electrode has exchange current densities of 6.84103 and 3.16103 mA/cm2 and Tafel slopes of 55.3 and 72.2 mV/dec, respectively. As an anode for oxygen evolution reaction (OER) in alkaline electrolyte, the electrode shows an exchange current density of 2.88104 mA/cm2 and Tafel slope of 49.3 mV/dec. The observed high activity of the electrode correlates well with its electronic structure, which was assessed by density functional theory (DFT) calculations. The stability of Fe0.2Ni0.8P2 electrocatalyst in HER and OER was evaluated by means of accelerated degradation test and chronopotentiometry. The results of these experiments elucidate partial dissolution and entire chemical transformation of Fe0.2Ni0.8P2 as the main mechanisms of the electrode degradation during HER and OER, respectively. Overall, our findings could facilitate the composition-based design of active, stable, and durable phosphide electrodes for electrochemical water splitting.We thank all members of the Nanomaterials Synthesis Unit at the INL for their fruitful scientific and technical input, as well as Dr. X. Wang for his help with the electrocatalytic data analysis. This investigation has benefited from the financial support provided by the European Union Horizon 2020 NMP programme through the CritCat project under grant agreement no. 686053, as well as ERDF funds through the Portuguese Operational Programme for Competitiveness and Internationalization (COMPETE 2020), and National Funds through the Portuguese Foundation for Science and Technology (FCT), under the PrintPV project PTDC/CTM-ENE/5387/2014 (grant agreement no. 016663). J.D.C. thanks the FCT PhD grant SFRH/BD/79393/2011, while J.L.L. thanks Marie-Curie-ITN607904-SPINOGRAPH project for the PhD grant

Ocorrência de Coccidoxenoides perminutus (Hymenoptera: Encyrtidae) parasitando Planococcus citri (Hemiptera: Pseudococcidae) em videira no Semiárido brasileiro.

SICONBIOL 2013

The variability behavior of CoRoT M-giant Stars

For 6 years the Convection, Rotation, and Planetary Transits (CoRoT) space mission has acquired photometric data from more than one hundred thousand point sources towards and directly opposite from the inner and outer regions of the Galaxy. The high temporal resolution of the CoRoT data combined with the wide time span of the observations has enabled the study of short and long time variations in unprecedented detail. From the initial sample of 2534 stars classified as M-giants in the CoRoT databasis, we selected 1428 targets that exhibit well defined variability, using visual inspection. The variability period and amplitude of C1 stars (stars having Teff < 4200 K) were computed using Lomb-Scargle and harmonic fit methods. The trends found in the V-I vs J-K color-color diagram are in agreement with standard empirical calibrations for M-giants. The sources located towards the inner regions of the Galaxy are distributed throughout the diagram while the majority of the stars towards the outer regions of the Galaxy are spread between the calibrations of M-giants and the predicted position for Carbon stars. The stars classified as supergiants follow a different sequence from the one found for giant stars. We also performed a KS test of the period and amplitude of stars towards the inner and outer regions of the Galaxy. We obtained a low probability that the two samples come from the same parent distribution. The observed behavior of the period-amplitude and period-Teff diagrams are, in general, in agreement with those found for Kepler sources and ground based photometry, with pulsation being the dominant cause responsible for the observed modulation. We also conclude that short-time variations on M-Giant stars do not exist orare very rare and the few cases we found are possibly related to biases or background stars.Comment: 11 pages, 6 figure

Honeydew of Planococcus citri (Pseudococcidae) increases longevity and locomotory activity of its parasitoid, Coccidoxenoides perminutus (Encyrtidae).

SICONBIOL 2013

Efficient building management with IP-based wireless sensor network

Existing Building/Energy Management Systems (BMS/EMS) fail to convey holistic performance to the building manager. A 20% reduction in energy consumption can be achieved by efficiently operated buildings compared with current practice. However, in the majority of buildings, occupant comfort and energy consumption analysis is primarily restricted by available sensor and meter data. Installation of a continuous monitoring process can significantly improve the building systems’ performance. We present WSN-BMDS, an IP-based wireless sensor network building monitoring and diagnostic system. The main focus of WSN-BMDS is to obtain much higher degree of information about the building operation then current BMSs are able to provide. Our system integrates a heterogeneous set of wireless sensor nodes with IEEE 802.11 backbone routers and the Global Sensor Network (GSN) web server. Sensing data is stored in a database at the back office via UDP protocol and can be access over the Internet using GSN. Through this demonstration, we show that WSN-BMDS provides accurate measurements of air-temperature, air-humidity, light, and energy consumption for particular rooms in our target building. Our interactive graphical user interface provides a user-friendly environment showing live network topology, monitor network statistics, and run-time management actions on the network. We also demonstrate actuation by changing the artificial light level in one of the rooms

Femtosecond control of electric currents at the interfaces of metallic ferromagnetic heterostructures

The idea to utilize not only the charge but also the spin of electrons in the operation of electronic devices has led to the development of spintronics, causing a revolution in how information is stored and processed. A novel advancement would be to develop ultrafast spintronics using femtosecond laser pulses. Employing terahertz (10$^{12}$ Hz) emission spectroscopy, we demonstrate optical generation of spin-polarized electric currents at the interfaces of metallic ferromagnetic heterostructures at the femtosecond timescale. The direction of the photocurrent is controlled by the helicity of the circularly polarized light. These results open up new opportunities for realizing spintronics in the unprecedented terahertz regime and provide new insights in all-optical control of magnetism.Comment: 3 figures and 2 tables in the main tex