Controlo por fase única de conversores A/D de baixa tensão

Este trabalho apresenta a aplicação de um controlo de fase única a um conversor concorrencial de baixa tensão. Com vista à validação da análise e conclusão teóricas, um conversor concorrencial de 10-bit 4 MS/s foi projectado e simulado. Foi primeiramente simulado com um controlo clássico de 6 fases, e posteriormente com um esquema de fase única. Os resultados de simulação mostram que as características globais são mantidas, apontando para que o uso de esquemas de fase única em conversores de baixa tensão seja uma solução que reduz a complexidade dos sistemas clássicos não sobrepostos.info:eu-repo/semantics/publishedVersio

Power-and-area efficient 14-bit 1.5 MSample/s two-stage algorithmic ADC based on a mismatch-insensitive MDAC

IEEE International Symposium on Circuits and Systems, pp. 220 – 223, Seattle, EUAThis paper presents a 14-bit 1.5 MSample/s two-stage algorithmic ADC with a power-and-area efficiency better than 0.5 pJmm2 per conversion. This competes with the most efficient architectures available today namely, ΣΔ and self-calibrated pipeline. The 2 stages of the ADC are based on a new 1.5-bit mismatch-insensitive MDAC and simulations demonstrate that a THD of –79 dB and an ENOB better than 12 bits can be reached without self-calibration

Influência de culturas antecessoras na disponibilidade de nitrogênio do solo para a cultura do algodão.

Um dos fatores importantes a ser considerado no manejo da adubação nitrogenada é a cultura antecessora. O objetivo desse trabalho, conduzido em Santa Helena de Goiás, foi medir a influência de culturas antecessoras na disponibilidade de nitrogênio (N) inorgânico no solo e na resposta do algodoeiro à adubação nitrogenada. O experimento foi instalado em parcelas subdivididas com quatro repetições. Nas parcelas foram cultivadas as culturas antecessoras milho, soja, algodão e Brachiaria decumbens; e nas subparcelas foram aplicadas cinco doses de nitrogênio (0, 40, 80, 120 e 160 kg ha-1 de N) no algodoeiro cultivado em sucessão. O algodoeiro em sucessão à soja e ao algodão necessita de menor quantidade de fertilizante nitrogenado, em comparação com a sucessão à braquiária e ao milho. Durante o ciclo do algodoeiro a presença de resíduos de soja favorece a mineralização líquida do nitrogênio do solo, tornando-o disponível nos primeiros estádios de desenvolvimento da planta. Os resíduos de B. decumbens favorecem a imobilização do N na biomassa microbiana do solo

Detrended Fluctuation Analysis of Systolic Blood Pressure Control Loop

We use detrended fluctuation analysis (DFA) to study the dynamics of blood pressure oscillations and its feedback control in rats by analyzing systolic pressure time series before and after a surgical procedure that interrupts its control loop. We found, for each situation, a crossover between two scaling regions characterized by exponents that reflect the nature of the feedback control and its range of operation. In addition, we found evidences of adaptation in the dynamics of blood pressure regulation a few days after surgical disruption of its main feedback circuit. Based on the paradigm of antagonistic, bipartite (vagal and sympathetic) action of the central nerve system, we propose a simple model for pressure homeostasis as the balance between two nonlinear opposing forces, successfully reproducing the crossover observed in the DFA of actual pressure signals

Feasibility randomized controlled trial of a self-guided online intervention to promote psychosocial adjustment to unmet parenthood goals

STUDY QUESTION Is it feasible to implement and evaluate an online self-guided psychosocial intervention for people with an unmet parenthood goal (UPG), aimed to improve well-being, in an online randomized controlled trial (RCT)? SUMMARY ANSWER The evaluation of an online bilingual self-guided psychosocial intervention for people with a UPG is feasible, reflected by high demand, good acceptability, good adaptation and promise of efficacy, but minor adjustments to the intervention and study design of the RCT should be made to enhance practicality. WHAT IS KNOWN ALREADY Self-identifying as having a UPG, defined as being unable to have children or as many as desired, is associated with impaired well-being and mental health. Practice guidelines and regulatory bodies have highlighted the need to address the lack of evidence-based support for this population. It is unknown if MyJourney (www.myjourney.pt), the first online self-guided intervention for people with UPGs, can be implemented and evaluated in an RCT. STUDY DESIGN, SIZE, DURATION To evaluate the feasibility of MyJourney, we conducted a registered, two-arm, parallel group, non-blinded feasibility RCT, with a 1:1 computer-generated randomized allocation and embedded qualitative process evaluation. Participants were included between November 2020 and March 2021. Assessments were made before randomization (T1), 10 weeks (T2) and 6 months after (T3, intervention group only). Participants allocated to the intervention group received an email to access MyJourney immediately after randomization. Participants in the waitlist control group were given access to MyJourney after completing the 10-week assessment (T2). PARTICIPANTS/MATERIALS, SETTING, METHODS Participants were recruited via social media advertising of MyJourney and its feasibility study. People who self-identified as having a UPG could click on a link to participate, and of these 235 were randomized. Outcome measures related to demand, acceptability, implementation, practicality, adaptation and limited efficacy were assessed via online surveys. The primary outcome in limited efficacy testing was hedonic well-being, measured with the World Health Organisation Wellbeing Index (WHO-5). MAIN RESULTS AND THE ROLE OF CHANCE Participation and retention rates were 58.3%, 31.7% (T2) and 45.2% (T3, intervention group only), respectively. Of participants invited to register with MyJourney, 91 (76.5%) set up an account, 51 (47.2%) completed the first Step of MyJourney, 12 (11.1%) completed six Steps (sufficient dose) and 6 (5.6%) completed all Steps within the 10-week recommended period. Acceptability ranged from 2.79 (successful at supporting) to 4.42 (easy to understand) on a 1 (not at all) to 5 (extremely acceptable) scale. Average time to complete sufficient dose was 15.6 h (SD = 18.15) and to complete all Steps was 12.4 h (SD = 18.15), with no differences found for participants using MyJourney in Portuguese and English. Modified intention-to-treat analysis showed a moderate increase in well-being from T1 to T2 in the intervention group (ηp2 = 0.156, mean difference (MD) = 9.300 (2.285, 16.315)) and no changes in the control group (ηp2 = 0.000, MD = 0.047 (−3.265, 3.358)). Participants in the process evaluation reported MyJourney was needed and answered their needs for support (reflecting high demand and acceptability), the recommended period to engage with MyJourney was short, and their engagement was influenced by multiple factors, including personal (e.g. lack of time) and MyJourney related (e.g. reminders). LIMITATIONS, REASONS FOR CAUTION Participants were mostly white, well-educated, employed, childless women. Non-blinded allocation, use of self-reported questionnaire assessments and high attrition in the intervention group could have triggered bias favourable to positive evaluations of MyJourney and resulted in low power to detect T2 to T3 changes in limited efficacy outcomes. WIDER IMPLICATIONS OF THE FINDINGS MyJourney can proceed to efficacy testing, but future work should eliminate barriers for engagement and explore strategies to maximize adherence. Entities wanting to support people with UPGs now have a freely accessible and promising resource that can be further tested and evaluated in different settings

Adubação NPK do algodoeiro em cultivo adensado de safrinha no Cerrado de Goiás - safra 2010/11.

O objetivo desse trabalho foi definir doses de NPK para adubação de manutenção do algodão de safrinha adensado, nas condições do Cerrado de Goiás, em função da fertilidade do solo, da expectativa de produtividade e das quantidades exportadas desses nutrientes pela cultura

A Unifying Theory of Biological Function

A new theory that naturalizes biological function is explained and compared with earlier etiological and causal role theories. Etiological theories explain functions from how they are caused over their evolutionary history. Causal role theories analyze how functional mechanisms serve the current capacities of their containing system. The new proposal unifies the key notions of both kinds of theories, but goes beyond them by explaining how functions in an organism can exist as factors with autonomous causal efficacy. The goal-directedness and normativity of functions exist in this strict sense as well. The theory depends on an internal physiological or neural process that mimics an organism’s fitness, and modulates the organism’s variability accordingly. The structure of the internal process can be subdivided into subprocesses that monitor specific functions in an organism. The theory matches well with each intuition on a previously published list of intuited ideas about biological functions, including intuitions that have posed difficulties for other theories

TRANSIENT MODELING OF A SMALL HYDROKINETIC TURBINE

In recent years, great attention has been given to the study of hydrokinetic turbines for power generation. Such importance is due to the use of clean energy technology by using renewable sources. Therefore, this work aims to present a relevant methodology for the efficient design of horizontal-axis hydrokinetic turbines with variable rotational speed. This methodology includes the Blade Element Method (BEM) for determining the turbine power coefficient, since BEM is widely used in the hydrokinetic turbine design due to its good agreement with experimental data. In addition, the dynamic equation of the driveline is used, taking into account the BEM to provide the rotor hydrodynamic torque coupled with the drive train model, including the multiplier and the electric generator. In this case, the modeling of the whole system comprises the hydrodynamic information of the rotor, the mass-moment of inertia, frictional losses and electromagnetic torque imposed by the generator. The theoretical results were obtained for the transient rotational speed and compared with field data measured from small hydrokinetic turbine installed at the Arapiranga-Açu creek, which is located in the city of Acará, Pará, Brazil

Interplay between pleiotropy and secondary selection determines rise and fall of mutators in stress response

Dramatic rise of mutators has been found to accompany adaptation of bacteria in response to many kinds of stress. Two views on the evolutionary origin of this phenomenon emerged: the pleiotropic hypothesis positing that it is a byproduct of environmental stress or other specific stress response mechanisms and the second order selection which states that mutators hitchhike to fixation with unrelated beneficial alleles. Conventional population genetics models could not fully resolve this controversy because they are based on certain assumptions about fitness landscape. Here we address this problem using a microscopic multiscale model, which couples physically realistic molecular descriptions of proteins and their interactions with population genetics of carrier organisms without assuming any a priori fitness landscape. We found that both pleiotropy and second order selection play a crucial role at different stages of adaptation: the supply of mutators is provided through destabilization of error correction complexes or fluctuations of production levels of prototypic mismatch repair proteins (pleiotropic effects), while rise and fixation of mutators occur when there is a sufficient supply of beneficial mutations in replication-controlling genes. This general mechanism assures a robust and reliable adaptation of organisms to unforeseen challenges. This study highlights physical principles underlying physical biological mechanisms of stress response and adaptation