Fully-parallel quantum turbo decoder

Quantum Turbo Codes (QTCs) are known to operate close to the achievable Hashing bound. However, the sequential nature of the conventional quantum turbo decoding algorithm imposes a high decoding latency, which increases linearly with the frame length. This posses a potential threat to quantum systems having short coherence times. In this context, we conceive a Fully- Parallel Quantum Turbo Decoder (FPQTD), which eliminates the inherent time dependencies of the conventional decoder by executing all the associated processes concurrently. Due to its parallel nature, the proposed FPQTD reduces the decoding times by several orders of magnitude, while maintaining the same performance. We have also demonstrated the significance of employing an odd-even interleaver design in conjunction with the proposed FPQTD. More specifically, it is shown that an odd-even interleaver reduces the computational complexity by 50%, without compromising the achievable performance

Biomassa tropical é alternativa energética do século XXI.

Os cientistas do planeta já acionaram o alarme. Sem o petróleo, a alternativa que resta à humanidade no século XXI é o aproveitamento da biomassa tropical para a produção de energia a partir de óleos vegetais. Roberto Miranda coordena o projeto da Embrapa na comunidade Boa União

Chemical vapour deposited ZnO nanowires for detecting Ethanol and NO2

Randomly oriented ZnO nanowires were grown directly onto alumina substrates having platinum interdigitated screen-printed electrodes via the chemical vapor deposition method using Au as catalyst. Three different Au film thicknesses (i.e., 3, 6 or 12 nm) were used in the growth of nanowires, and their gas sensing properties were studied for ethanol and NO2 as reducing and oxidizing species, respectively. ZnO nanowires grown employing the 6 nm thick layers were the less defective and showed the most stable, repeatable gas sensing properties. Despite ZnO nanowires grown employing the thickest Au layers reached the highest responses under dry conditions, ZnO nanowires grown using the thinnest Au film were more resilient at detecting NO2 in the presence of ambient moisture. The gas sensing results are discussed in light of the defects and the presence of Au impurities in the ZnO nanowires, as revealed by the characterization techniques used, such as X-ray diffraction, field-emission scanning electron microscopy, X-ray photoelectron spectroscopy and photoluminescence spectroscopy. Promising results were obtained by the implementation of ZnO NWs directly grown over alumina substrates for the detection of ethanol and NO2, substantially ameliorating our previously reported results

Procesos de la gestión de riesgo tecnológico en consultores ambientales privados

The present study aimed to identify the processes involved in managing technological risk used in environmental projects carried out by private environmental consultants. A descriptive, cross-sectional, non-experimental, field study was carried out, based on the theoretical contributions of Negro (2000) and Hidalgo et al (2002). Data was collected through observation using a survey; its reliability was determined by calculating the Cronbach Alpha coefficient, whose value was 0.84, highly reliable. It was shown that the processes most used to manage risk associated with technological tools were impact planning and analysis, with the second heading this phase. However, results agree on considering the identification process as an aspect immersed in the preliminary stages of all projects. The study proposes promoting the individualized identification of risk process, mainly in preliminary stages of project implementation.  La presente investigación tuvo como objetivo la identificación de los procesos implicados en la gestión del riesgo tecnológico que se emplea en los proyectos ambientales llevados a cabo en consultores ambientales privados. Se realizó mediante un estudio descriptivo, transeccional, de campo y no experimental, sustentado en los aportes teóricos de Negrão (2000) e Hidalgo et al (2002). La recopilación de la información se realizó por observación mediante encuesta. Se determinó la confiabilidad calculando el coeficiente Alfa-Cronbach; el valor obtenido para este coeficiente fue 0.84, siendo éste altamente confiable. Se demostró que los procesos más utilizados para la gestión de riesgo ligados a herramientas tecnológicas, fueron la planificación del impacto y el análisis, siendo el segundo el encabezado de esta fase. Sin embargo, se coincide en la consideración del proceso de la identificación como un aspecto que se encuentra inmerso dentro de las etapas preliminares de todo proyecto. Se propone con ello, promover el proceso de identificación individualizada del riesgo, principalmente en las etapas preliminares a la ejecución del proyecto

Evaluation of Retromolar Canals using Cone Beam Computer Tomography/ Avaliação do canal retromolar por meio de tomografia computadorizada de feixe cônico

The aim of this study was to evaluate the prevalence, location and clinical implications related to the presence of the retromolar canal (RMC) on cone beam computed tomography(CBCT). CBCT images of patients from Latin America Institute for Dental Research and Education - Curitiba,Pr,Brazil, was performed from June/2008 to February/2013. The interpretation was performed by a calibrated examiner, according to the criterias: presence, location and classification of the RMC variation, as well as, measurements of horizontal distances of the RMC in relation to the buccal bone cortical and diameter of these canals. A total of 751 CBCT images were interpreted: 486(64.7%) from females and 265 (35.3%) from male patients, with mean age of 54.57 (±13.23) years. The presence of RMC was observed in 58 (7.7%) patients, 23 men and 35 women. A total of 1502 hemi- mandibles were analyzed. The RMC was identified in 69(4.6%) hemi-mandibles, 44(63.8%) from females and 25(36.2%) from males. Thirty (42.8%) RMC were observed on the right side and 40 (57.2%) on the left one. The type B1 (n=33; 47.1%) was the most common, followed by the type A1 (n=18;25.7%). The mean diameter of RMC was 0.97mm (±0.44), and the mean distance between retromolar foramen and the buccal cortical of the mandible was 4.12mm (±1.35). There were no significant differences between the distances and genders, and distances and sides (p > 0.05). The prevalence of RMC was 7.7% in the studied sample; they were predominantly unilateral and showed to be type B1

Photoluminescence of ZnO Nanowires: A Review

One-dimensional ZnO nanostructures (nanowires/nanorods) are attractive materials for applications such as gas sensors, biosensors, solar cells, and photocatalysts. This is due to the relatively easy production process of these kinds of nanostructures with excellent charge carrier transport properties and high crystalline quality. In this work, we review the photoluminescence (PL) properties of single and collective ZnO nanowires and nanorods. As different growth techniques were obtained for the presented samples, a brief review of two popular growth methods, vapor-liquid-solid (VLS) and hydrothermal, is shown. Then, a discussion of the emission process and characteristics of the near-band edge excitonic emission (NBE) and deep-level emission (DLE) bands is presented. Their respective contribution to the total emission of the nanostructure is discussed using the spatial information distribution obtained by scanning transmission electron microscopy−cathodoluminescence (STEM-CL) measurements. Also, the influence of surface effects on the photoluminescence of ZnO nanowires, as well as the temperature dependence, is briefly discussed for both ultraviolet and visible emissions. Finally, we present a discussion of the size reduction effects of the two main photoluminescent bands of ZnO. For a wide emission (near ultra-violet and visible), which has sometimes been attributed to different origins, we present a summary of the different native point defects or trap centers in ZnO as a cause for the different deep-level emission bands

Influence of colloidal Au on the growth of ZnO nanostructures

Vapor-liquid-solid processes allow growing high-quality nanowires from a catalyst. An alternative to the conventional use of catalyst thin films, colloidal nanoparticles offer advantages not only in terms of cost, but also in terms of controlling the location, size, density, and morphology of the grown nanowires. In this work, we report on the influence of different parameters of a colloidal Au nanoparticle suspension on the catalyst-assisted growth of ZnO nanostructures by a vapor-transport method. Modifying colloid parameters such as solvent and concentration, and growth parameters such as temperature, pressure, and Ar gas flow, ZnO nanowires, nanosheets, nanotubes and branched-nanowires can be grown over silica on silicon and alumina substrates. High-resolution transmission electron microscopy reveals the high-crystal quality of the ZnO nanostructures obtained. The photoluminescence results show a predominant emission in the ultraviolet range corresponding to the exciton peak, and a very broad emission band in the visible range related to different defect recombination processes. The growth parameters and mechanisms that control the shape of the ZnO nanostructures are here analyzed and discussed. The ZnO-branched nanowires were grown spontaneously through catalyst migration. Furthermore, the substrate is shown to play a significant role in determining the diameters of the ZnO nanowires by affecting the surface mobility of the metal nanoparticles

Role of aluminum and HMTA in the hydrothermal synthesis of two-dimensional n-doped ZnO nanosheets

This work reports the study of the processes behind the growth of two-dimensional (2D) n-doped ZnO nanostructures on an AlN layer. We have demonstrated that AlN undergoes a slow dissociation process due to the basic controlled environment promoted by the hexamethylenetetramine (HMTA). The Al(OH)4- ions created inhibits the growth along the c-axis, effectively promoting the fast formation of a planar geometry selectively grown on top of the AlN layer. With the use of this promoting layer and a standard hydrothermal method, a selective area growth is observed with micrometric resolution. In addition, by using several advanced characterization techniques such as, X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS/EDX), X-ray photoelectron spectroscopy (XPS) and photoluminescence (PL), we observed a resulting doping with aluminum of the ZnO nanostructures, occupying substitutional and interstitial sites, that could lead to new promising applications. These high-quality n-doped ZnO nanosheets (NSs) exhibit strong ultraviolet emission in the 385-405 nm region without broad deep level emission. The piezoelectric nature of these nanostructures has been demonstrated by using piezoresponse atomic force microscope (PFM) and with the support of a piezoelectric test device. Therefore, this low-cost and fast selective-area synthesis of 2D n-doped ZnO NSs can be applicable to other aluminum based materials and paves the way to new promising applications, such as bioelectronic applications, energy generation or self-powered sensin

PdO and PtO doped WS2 boosts NO2 gas sensing characteristics at room temperature

In this work tungsten disulphide nanostructures loaded with platinum-oxide (PtO), or palladium-oxide (PdO) were grown directly onto alumina substrates. This was achieved using a combination of aerosol-assisted chemical vapour deposition (AA-CVD) method with atmospheric pressure CVD technique. At first, tungsten oxide nanowires loaded with either PtO or PdO nanoparticles were successfully co-deposited via AA-CVD followed by sulfurization at 900 °C in the next step. The morphological, structural, and chemical characteristics were investigated using FESEM, TEM, XRD, XPS and Raman spectroscopy. The results confirm the presence of PdO and PtO in the WS2 host matrix. Gas sensing attributes of loaded and pristine WS2 sensors were investigated, at room temperature, towards different analytes (NO2, NH3, H2 etc.). Both pristine and metal-oxide loaded WS2 gas sensors show remarkable responses at room temperature towards NO2 detection. Further, the loaded sensors demonstrated stable, reproducible, ultrasensitive, and enhanced gas sensing response, with a detection limit below 25 ppb. Additionally, the effect of ambient humidity on the sensing response of both loaded and pristine sensors was investigated for NO2 gas. The response of PtO loaded sensor considerably decreased in humid environments, while the response for pristine and PdO loaded sensors increased. However, slightly heating (at 100 °C) the sensors, suppresses the influence of humidity. Finally, the long-term stability of different sensors is investigated, and the results demonstrate high stability with repeatable results after 6 weeks of gas sensing tests. This work exploits an attractive pathway to add functionality in the transition metal dichalcogenide host matrix

Chronic stress deficits in reward behaviour co-occur with low nucleus accumbens dopamine activity during reward anticipation specifically

Whilst reward pathologies are major and common in stress-related neuropsychiatric disorders, their neurobiology and treatment are poorly understood. Imaging studies in human reward pathology indicate attenuated BOLD activity in nucleus accumbens (NAc) coincident with reward anticipation but not reinforcement; potentially, this is dopamine (DA) related. In mice, chronic social stress (CSS) leads to reduced reward learning and motivation. Here, DA-sensor fibre photometry is used to investigate whether these behavioural deficits co-occur with altered NAc DA activity during reward anticipation and/or reinforcement. In CSS mice relative to controls: (1) Reduced discriminative learning of the sequence, tone-on + appetitive behaviour = tone-on + sucrose reinforcement, co-occurs with attenuated NAc DA activity throughout tone-on and sucrose reinforcement. (2) Reduced motivation during the sequence, operant behaviour = tone-on + sucrose delivery + sucrose reinforcement, co-occurs with attenuated NAc DA activity at tone-on and typical activity at sucrose reinforcement. (3) Reduced motivation during the sequence, operant behaviour = appetitive behaviour + sociosexual reinforcement, co-occurs with typical NAc DA activity at female reinforcement. Therefore, in CSS mice, low NAc DA activity co-occurs with low reward anticipation and could account for deficits in learning and motivation, with important implications for understanding human reward pathology