Chemical Power for Microscopic Robots in Capillaries

The power available to microscopic robots (nanorobots) that oxidize bloodstream glucose while aggregated in circumferential rings on capillary walls is evaluated with a numerical model using axial symmetry and time-averaged release of oxygen from passing red blood cells. Robots about one micron in size can produce up to several tens of picowatts, in steady-state, if they fully use oxygen reaching their surface from the blood plasma. Robots with pumps and tanks for onboard oxygen storage could collect oxygen to support burst power demands two to three orders of magnitude larger. We evaluate effects of oxygen depletion and local heating on surrounding tissue. These results give the power constraints when robots rely entirely on ambient available oxygen and identify aspects of the robot design significantly affecting available power. More generally, our numerical model provides an approach to evaluating robot design choices for nanomedicine treatments in and near capillaries.Comment: 28 pages, 7 figure

Positive Selection of B Cells Expressing Low Densities of Self-reactive BCRs

B cell tolerance or autoimmunity is determined by selective events. Negative selection of self-reactive B cells is well documented and proven. In contrast, positive selection of conventional B cells is yet to be firmly established. Here, we demonstrate that developing self-reactive B cells are not always highly sensitive to the deletion mechanisms imposed by membrane-bound self-antigens. At low amounts, membrane-bound antigens allow survival of B cells bearing a single high affinity self-reactive B cell receptor (BCR). More importantly, we show that forced allelic inclusion modifies B cell fate; low quantities of self-antigen induce the selection and accumulation of increased numbers of self-reactive B cells with decreased expression of antigen-specific BCRs. By directly measuring antigen binding by intact B cells, we show that the low amounts of self-antigen select self-reactive B cells with a lower association constant. A fraction of these B cells is activated and secretes autoantibodies that form circulating immune complexes with self-antigen. These findings demonstrate that conventional B cells can undergo positive selection and that the fate of a self-reactive B cell depends on the quantity of self-antigen, the number of BCRs engaged, and on its overall antigen-binding avidity, rather than on the affinity of individual BCRs

A Strategy for Selecting Classes of Symbols from Classes of Graphemes in HMM-Based Handwritten Word Recognition

This paper presents a new strategy for selecting classes of symbols from classes of graphemes in HMM-based handwritten word recognition from Brazilian legal amounts. This paper discusses features, graphemes and symbols, as our baseline system is based on a global approach in which the explicit segmentation of words into letters or pseudo-letters is avoided and HMM models are used. For this framework, the input data are the symbols of an alphabet based on graphemes extracted from the word images visible on the Hidden Markov Model. The idea is to introduce high-level concepts, such as perceptual features (loops, ascenders, descenders, concavities and convexities) and to provide fast and informative feedback about the information contained in each class of grapheme for symbol class selection. The paper presents an algorithm based on Mutual Information and HMM working in the same evaluation process. Finally, the experimental results demonstrate that it is possible to select from the “original” grapheme set (composed of 94 graphemes) an alphabet of symbols (composed of 29 symbols). We conclude that the discriminating power of the grapheme is very important for consolidating an alphabet of symbols.Este artigo descreve uma metodologia para seleção de classes de símbolos a partir de classesde grafemas em um sistema de reconhecimento de palavras manuscritas do extenso de cheques bancáriosbrasileiros baseado em HMM (Hidden Markov Models). Este artigo discute as definições de primitivas,grafemas e símbolos considerando um enfoque Global para o reconhecimento das palavras, o qual evita asegmentação das palavras em letras ou pseudo-letras utilizando HMM. Assim, a entrada para os modelosconsiste em uma descrição da palavra a partir de um alfabeto de símbolos gerados a partir dos grafemasextraídos das imagens das palavras, sendo esta a representação visível para o HMM. Portanto, a idéia éintroduzir uma conceituação de alto nível, tais como primitivas perceptivas (laços, ascendentes,descendentes, concavidades e convexidades) e fornecer um modo de retro-alimentação rápido e informativosobre a informação contida em cada classe de grafema, permitindo uma seleção de classes de símbolos. Oartigo apresenta o algoritmo com base na Informação Mútua (Mutual Information) e HMM, ambostrabalhando em um mesmo processo de avaliação. Os resultados experimentais demonstram que é possívelselecionar a partir de um conjunto “original” de grafemas (composto por 94 grafemas) um alfabeto desímbolos (composto por 29 símbolos). O artigo conclui que o poder discriminante dos grafemas é muitoimportante para a consolidação de um alfabeto de símbolos.Este artigo descreve uma metodologia para seleção de classes de símbolos a partir de classesde grafemas em um sistema de reconhecimento de palavras manuscritas do extenso de cheques bancáriosbrasileiros baseado em HMM (Hidden Markov Models). Este artigo discute as definições de primitivas,grafemas e símbolos considerando um enfoque Global para o reconhecimento das palavras, o qual evita asegmentação das palavras em letras ou pseudo-letras utilizando HMM. Assim, a entrada para os modelosconsiste em uma descrição da palavra a partir de um alfabeto de símbolos gerados a partir dos grafemasextraídos das imagens das palavras, sendo esta a representação visível para o HMM. Portanto, a idéia éintroduzir uma conceituação de alto nível, tais como primitivas perceptivas (laços, ascendentes,descendentes, concavidades e convexidades) e fornecer um modo de retro-alimentação rápido e informativosobre a informação contida em cada classe de grafema, permitindo uma seleção de classes de símbolos. Oartigo apresenta o algoritmo com base na Informação Mútua (Mutual Information) e HMM, ambostrabalhando em um mesmo processo de avaliação. Os resultados experimentais demonstram que é possívelselecionar a partir de um conjunto “original” de grafemas (composto por 94 grafemas) um alfabeto desímbolos (composto por 29 símbolos). O artigo conclui que o poder discriminante dos grafemas é muitoimportante para a consolidação de um alfabeto de símbolos

Multiplicative mixed-effects modelling of dengue incidence: an analysis of the 2019 outbreak in the Dominican Republic

Dengue is a vector-borne disease that is endemic to several countries, including the Dominican Republic, which has experienced dengue outbreaks for over four decades. With outbreaks growing in incidence in recent years, it is becoming increasingly important to develop better tools to understand drivers of dengue transmission. Such tools are critical for providing timely information to assist healthcare authorities in preparing human, material, and medical resources for outbreaks. Here, we investigate associations between meteorological variables and dengue transmission in the Dominican Republic in 2019, the year in which the country’s largest outbreak to date ocurred. We apply generalized linear mixed modelling with gamma family and log link to model the weekly dengue incidence rate. Because correlations in lags between climate variables and dengue cases exhibited different behaviour among provinces, a backward-type selection method was executed to find a final model with lags in the explanatory variables. We find that in the best models, meteorological conditions such as temperature and rainfall have an impact with a delay of 2–5 weeks in the development of an outbreak, ensuring breeding conditions for mosquitoes.publishe

ROSAT observations of X-ray emission from planetary nebulae

We have searched the entire ROSAT archive for useful observations to study X-ray emission from Galactic planetary nebulae (PNs). The search yields a sample of 63 PNs, which we call the ROSAT PN sample. About 20-25% of this sample show X-ray emission; these include 13 definite detections and three possible detections (at a 2-sigma level). All X-ray sources in these PNs are concentrated near the central stars. Only A 30, BD+30 3639, and NGC 6543 are marginally resolved by the ROSAT instruments. Three types of X-ray spectra are seen in PNs. Type 1 consists of only soft X-ray emission (<0.5 keV), peaks at 0.1-0.2 keV, and can be fitted by blackbody models at temperatures 1-2 10^5 K. Type 2 consists of harder X-ray emission, peaks at >0.5 keV, and can be fitted by thin plasma emission models at temperatures of a few 10^6 K. Type 3 is a composite of a bright Type 1 component and a fainter Type 2 component. Unresolved soft sources with Type 1 spectra or the soft component of Type 3 spectra are most likely photospheric emission from the hot central stars. Absorption cross sections are large for these soft-energy photons; therefore, only large, tenuous, evolved PNs with hot central stars and small absorption column densities have been detected. The origin of hard X-ray emission from PNs is uncertain. PNs with Type 2 spectra are small, dense, young nebulae with relatively cool (<<10^5 K) central stars, while PNs with Type 3 X-ray spectra are large, tenuous, evolved nebulae with hot central stars. The hard X-ray luminosities are also different between these two types of PNs, indicating perhaps different origins of their hard X-ray emission. Future Chandra and XMM observations with high spatial and spectral resolution will help to understand the origin of hard X-ray emission from PNs.Comment: To be published in The Astrophysical Journal Supplement Series. 21 pages, 7 figures, 5 table

Does high-velocity resistance exercise elicit greater physical function benefits than traditional resistance exercise in older adults? A systematic review and network meta-analysis of 79 trials

Background A systematic review and network meta-analysis was undertaken to examine the effectiveness of different modes of resistance exercise velocity in fast walking speed, timed-up and go, 5-times sit-to-stand, 30-second sit-to-stand, and 6-minute walking tests in older adults. Methods CINAHL, Embase, LILACS, PubMed, Scielo, SPORTDiscus, and Web of Science databases were searched up to February 2022. Eligible randomized trials examined the effects of supervised high-velocity or traditional resistance exercise in older adults (ie, ≥ 60 years). The primary outcome for this review was physical function measured by fast walking speed, timed-up and go, 5-times sit-to-stand, 30-second sit-to-stand, and 6-minute walking tests, while maximal muscle power and muscle strength were secondary. A random-effects network meta-analysis was undertaken to examine the effects of different resistance exercise interventions. Results Eighty articles describing 79 trials (n = 3 575) were included. High-velocity resistance exercise was the most effective for improving fast walking speed (standardized mean difference [SMD] −0.44, 95% confidence interval [CI]: 0.00 to 0.87), timed-up and go (SMD −0.76, 95% CI: −1.05 to −0.47), and 5-times sit-to-stand (SMD −0.74, 95% CI: −1.20 to −0.27), while traditional resistance exercise was the most effective for 30-second sit-to-stand (SMD 1.01, 95% CI: 0.68 to 1.34) and 6-minute walking (SMD 0.68, 95% CI: 0.34 to 1.03). Conclusion Our study provides evidence that resistance exercise velocity effects are specific in older adults, as evidenced by physical function test dependence. We suggest that prescriptions based on the velocity of contraction should be individualized to address the specific functional needs of participants

747-1 Progression of Aortic Regurgitation Assessed by Doppler Echocardiography in 127 Patients: Degree of Regurgitation

To assess the progression of chronic aortic regurgitation (AR), 127 patients 169 men; 59±21 yr) with AR (59 mild, 8 mild-to-moderate, 41 moderate, 4 moderate-to-severe, 15 severe) who had ≥6 months of follow-up (6–47 months) by color Doppler and 2-D echo were studied. The degree of AR was established at entry and follow-up studies using an algorithm (semi-quantitative) that takes into account several Doppler criteria (jet area and jet height ratios, jet length, pressure half-time, reversal of flow in descending aorta) and the jet height/LV outflow tract (LVOT) height ratio (quantitative). LV volume (Simpson) and LV mass (Devereux) were calculated. A significant increase in jet/LVOT height ratio was observed in the whole population (30±17 vs. 35±20%; p&lt;0.00001) and in the subsets of patients with mild (18±7 vs. 22.3±9%; p&lt;0.01), moderate (40±14 vs. 44±16%; p&lt;0.01) and severe (54±19 vs. 65±15%; p&lt;0.05) AR. An increase in the degree of AR (semi-quantitative) during the follow-up was observed in 38 (30%) of patients: 25% with mild, 37% with mild-to-moderate, 44% with moderate and 50% with moderate-to-severe AR (p&lt;0.006). Patients were further divided according to the rank order in the rate of progression of jet/LVOT height ratio into “progressives” (n=18; rate&gt;5.64%/yr) and “non-progressives” (n=109). Patients with “progressive” AR had a faster rate of progression of LV end-diastolic volume, LV end-systolic volume and LV mass than “non-progressives” (p&lt;0.025).ConclusionsAR is a progressive disease even in patients with mild insufficiency. The progression in the degree of AR is more frequent in patients with more severe disease. The rate of progression of regurgitation appears to playa role in LV overload in patients with AR

Skeletal maturity and socio-economic status in portuguese children and youths: the Madeira growth study

Skeletal maturity is used to evaluate biological maturity status. Information about the association between socio-economic status (SES) and skeletal maturity is limited in Portugal. Aims: The aim of this study is to document the skeletal maturity of youths in Madeira and to evaluate variation in maturity associated with SES. Subjects and methods: The study involved 507 subjects (256 boys and 251 girls) from the Madeira Growth Study, a mixed-longitudinal study of five cohorts (8, 10, 12, 14 and 16 years of age) followed at yearly intervals over 3 years (1996–1998). A total of 1493 observations were made. Skeletal age was estimated from radiographs of the hand and wrist using the Tanner–Whitehouse 2 method (TW2). Social class rankings were based on Graffar’s (1956) method. Five social rankings were subsequently grouped into three SES categories: high, average and low. Results: Median for the radius, ulna and short finger bones (RUS scores) in the total sample of boys and girls increased curvilinearly across age whereas median for the 7 (without pisiform) carpal bones (Carpal scores) increased almost linearly. The 20-bone maturity scores demonstrated distinctive trends by gender: the medians for boys increased almost linearly while the medians for girls increased curvilinearly. SES differences were minimal. Only among children aged 10–11 years were high SES boys and girls advanced in skeletal maturity. Madeira adolescents were advanced in skeletal maturity compared with Belgian reference values. Conclusion: The data suggests population variation in TW2 estimates of skeletal maturation. Skeletal maturity was not related to SES in youths from Madeira

Shifting perspectives on coastal impacts and adaptation

The Intergovernmental Panel on Climate Change reports reflect evolving attitudes in adapting to sea-level rise by taking a systems approach and recognizing that multiple responses exist to achieve a less hazardous coast.info:eu-repo/semantics/publishedVersio