22 research outputs found
Sistema Anti-Melgas I: identificação e localização de fontes sonoras
This dissertation addresses the development of an acoustic localisation system with
the aim of detecting mosquitoes indoors. It starts with a brief study of the sound
produced by insects, with special focus on the case of female mosquitoes, aimed at
understanding the spectral characteristics; A review was carried out on our auditory
system and its ability to spatially locate sound sources. The main 2D cues are ITD
(interaural time difference) and ILD (interaural level difference). The example of
human hearing shows how spatial diversity of sensors is indispensable for sound
localisation; A 2D scenario was assumed, thus reducing the problem to azimuth
estimation, which requires two microphones. Assuming that the distance from
the source to the receiver is much greater than the distance between microphones
(far-field approximation) the sought azimuth angle can be obtained by an approximate
formula. The intrinsic error caused by the far-field approximation itself was
assessed, as well as the impact of possible estimation errors in the calculation parameters:
speed of sound, microphone spacing and time delay; The development
work, carried out on a MATLAB environment, was based on an existing simulator.
The central element of the system is the digital processing of the signals received
at the two microphones. The cross-correlation method is used to work out the
time delay between them. Interpolation was applied to increase the resolution of
the cross-correlation peak estimate; A script featuring a graphical interface was
developed to combine the predictor with the simulator. It makes it easy for the
user to specify the trajectory to be reproduced in the simulator. The audio file
to be injected is also chosen by the user. The simulator returns a stereo file with
the microphone signals. The script generates a pointer moving in real time to
indicate the estimated position of the source; Several other simulations and experimental
tests were carried out, based on an anechoic room without additional
sources of noise. The azimuth estimation error measured in simulation confirmed
the predicted behaviour taking into account the sources of error intrinsic to the
far-field approximation. The error is smaller when the source is between 45° and
135°. Outside this range, it increases, peaking at the extremes (0° and 180°). It
approaches zero when the source is at 90°, forming a symmetric U-shaped pattern
around this value. When noise is introduced, the estimations made lose quality, as
expected; for SNR less than -10 dB, the error exceeds 10°; The experimental tests
involved two microphones, a loudspeaker and an audio interface for communication
with the computer. An absorbing chamber has been created to reduce sound
reflections and external noise. Recordings of long duration were made for each
azimuth angle. With all the files processed, the pattern of the azimuth estimation
error was also U-shaped, although not perfectly symmetric.Esta dissertação aborda o desenvolvimento de um sistema de localização acústica
com o objectivo de detectar mosquitos dentro de casa. Começou com um breve
estudo do som produzido pelos insectos, especialmente os mosquitos fêmea, com
o objectivo de compreender as características espectrais; Foi realizada uma revisão
do nosso sistema auditivo e da sua capacidade de localizar espacialmente fontes
sonoras. As principais pistas 2D são ITD (interaural time difference) e ILD (interaural
level difference). O exemplo da audição humana mostra como a diversidade
espacial dos sensores é indispensável para a localização do som; Assumiu-se um
cenário 2D, reduzindo assim o problema da estimativa de azimute, que requer dois
microfones. Assumindo que a distância da fonte ao receptor é muito maior do
que a distância entre microfones (aproximação “far-field”), o ângulo de azimute
procurado pode ser obtido através de uma fórmula aproximada. Foi avaliado o
erro intrínseco causado pela própria aproximação “far-field”, bem como o impacto
de possíveis erros na estimativa dos parâmetros de cálculo: velocidade do som,
espaçamento entre microfones e atraso temporal; O trabalho de desenvolvimento,
realizado no ambiente MATLAB, foi baseado num simulador existente. O elemento
central do sistema é o processamento digital dos sinais recebidos nos dois microfones.
O método de correlação cruzada é utilizado para calcular o tempo de espera
entre eles. A interpolação foi aplicada para aumentar a resolução da estimativa do
pico de correlação cruzada; Foi desenvolvido um script com uma interface gráfica
para combinar o preditor com o simulador. Facilita ao utilizador a especificação da
trajectória a reproduzir no simulador. O ficheiro de áudio a ser injectado é também
escolhido pelo utilizador. O simulador devolve um ficheiro estéreo com os sinais
do microfone. O script gera um ponteiro que se move em tempo real para indicar
a posição estimada da fonte; Foram realizadas simulações e testes experimentais,
numa sala anecóica sem fontes adicionais de ruído. O erro da estimativa de azimute
medido na simulação confirmou o comportamento previsto, tendo em conta
as fontes de erro intrínsecas à aproximação “far-field”. O erro é menor quando a
fonte se situa entre 45° e 135°. Fora deste intervalo, aumenta, atingindo um pico
nos extremos (0° e 180°). Aproxima-se de zero quando a fonte está a 90°, formando
um padrão simétrico em forma de U em torno deste valor. Quando o ruído
é introduzido, as estimativas feitas perdem qualidade, como esperado; para SNR
inferior a -10 dB, o erro ultrapassa os 10°; Os testes experimentais consistiram em
dois microfones, um altifalante e uma interface de áudio para comunicar com o
computador. Foi criada uma câmara de absorção para reduzir os reflexos acústicos
e o ruído externo. Foram feitas gravações para cada ângulo de azimute, com longa
duração. Com todos os ficheiros processados, o padrão do erro de estimativa do
azimute também teve a forma de U, embora não tenha tido uma simetria perfeita.Mestrado em Engenharia Eletrónica e Telecomunicaçõe
Nationwide access to endovascular treatment for acute ischemic stroke in portugal
Publisher Copyright: Copyright Ordem dos M dicos 2021.Introduction: Since the publication of endovascular treatment trials and European Stroke Guidelines, Portugal has re-organized stroke healthcare. The nine centers performing endovascular treatment are not equally distributed within the country, which may lead to differential access to endovascular treatment. Our main aim was to perform a descriptive analysis of the main treatment metrics regarding endovascular treatment in mainland Portugal and its administrative districts. Material and Methods: A retrospective national multicentric cohort study was conducted, including all ischemic stroke patients treated with endovascular treatment in mainland Portugal over two years (July 2015 to June 2017). All endovascular treatment centers contributed to an anonymized database. Demographic, stroke-related and procedure-related variables were collected. Crude endovascular treatment rates were calculated per 100 000 inhabitants for mainland Portugal, and each district and endovascular treatment standardized ratios (indirect age-sex standardization) were also calculated. Patient time metrics were computed as the median time between stroke onset, first-door, and puncture. Results: A total of 1625 endovascular treatment procedures were registered. The endovascular treatment rate was 8.27/100 000 inhabitants/year. We found regional heterogeneity in endovascular treatment rates (1.58 to 16.53/100 000/year), with higher rates in districts closer to endovascular treatment centers. When analyzed by district, the median time from stroke onset to puncture ranged from 212 to 432 minutes, reflecting regional heterogeneity. Discussion: Overall endovascular treatment rates and procedural times in Portugal are comparable to other international registries. We found geographic heterogeneity, with lower endovascular treatment rates and longer onset-to-puncture time in southern and inner regions. Conclusion: The overall national rate of EVT in the first two years after the organization of EVT-capable centers is one of the highest among European countries, however, significant regional disparities were documented. Moreover, stroke-onset-to-first-door times and in-hospital procedural times in the EVT centers were comparable to those reported in the randomized controlled trials performed in high-volume tertiary hospitalspublishersversionpublishe
Acesso a Tratamento Endovascular para Acidente Vascular Cerebral Isquémico em Portugal
Introduction: Since the publication of endovascular treatment trials and European Stroke Guidelines, Portugal has re-organized stroke
healthcare. The nine centers performing endovascular treatment are not equally distributed within the country, which may lead to differential
access to endovascular treatment. Our main aim was to perform a descriptive analysis of the main treatment metrics regarding
endovascular treatment in mainland Portugal and its administrative districts.
Material and Methods: A retrospective national multicentric cohort study was conducted, including all ischemic stroke patients treated
with endovascular treatment in mainland Portugal over two years (July 2015 to June 2017). All endovascular treatment centers contributed
to an anonymized database. Demographic, stroke-related and procedure-related variables were collected. Crude endovascular
treatment rates were calculated per 100 000 inhabitants for mainland Portugal, and each district and endovascular treatment standardized
ratios (indirect age-sex standardization) were also calculated. Patient time metrics were computed as the median time between
stroke onset, first-door, and puncture.
Results: A total of 1625 endovascular treatment procedures were registered. The endovascular treatment rate was 8.27/100 000
inhabitants/year. We found regional heterogeneity in endovascular treatment rates (1.58 to 16.53/100 000/year), with higher rates in
districts closer to endovascular treatment centers. When analyzed by district, the median time from stroke onset to puncture ranged
from 212 to 432 minutes, reflecting regional heterogeneity.
Conclusion: The overall national rate of EVT in the first two years after the organization of EVT-capable centers is one of the highest among European countries, however, significant regional disparities were documented. Moreover, stroke-onset-to-first-door times and
in-hospital procedural times in the EVT centers were comparable to those reported in the randomized controlled trials performed in
high-volume tertiary hospitals.Introdução: A aprovação do tratamento endovascular para o acidente vascular cerebral isquémico obrigou à reorganização dos
cuidados de saúde em Portugal. Os nove centros que realizam tratamento endovascular não estão distribuídos equitativamente pelo
território, o que poderá causar acesso diferencial a tratamento. O principal objetivo deste estudo é realizar uma análise descritiva da
frequência e métricas temporais do tratamento endovascular em Portugal continental e seus distritos.
Material e Métodos: Estudo de coorte nacional multicêntrico, incluindo todos os doentes com acidente vascular cerebral isquémico
submetidos a tratamento endovascular em Portugal continental durante um período de dois anos (julho 2015 a junho 2017). Foram
colhidos dados demográficos, relacionados com o acidente vascular cerebral e variáveis do procedimento. Taxas de tratamento endovascular
brutas e ajustadas (ajuste indireto a idade e sexo) foram calculadas por 100 000 habitantes/ano para Portugal continental e
cada distrito. Métricas de procedimento como tempo entre instalação, primeira porta e punção foram também analisadas.
Resultados: Foram registados 1625 tratamentos endovasculares, indicando uma taxa bruta nacional de tratamento endovascular
de 8,27/100 000 habitantes/ano. As taxas de tratamento endovascular entre distritos variaram entre 1,58 e 16,53/100 000/ano, com
taxas mais elevadas nos distritos próximos a hospitais com tratamento endovascular. O tempo entre sintomas e punção femural entre
distritos variou entre 212 e 432 minutos.
Conclusão: Portugal continental apresenta uma taxa nacional de tratamento endovascular elevada, apresentando, contudo, assimetrias
regionais no acesso. As métricas temporais foram comparáveis com as observadas nos ensaios clínicos piloto
Batalha contra o charlatanismo: institucionalização da medicina científica na província de Goiás
Pervasive gaps in Amazonian ecological research
Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear un derstanding of how ecological communities respond to environmental change across time and space.3,4
While the increasing availability of global databases on ecological communities has advanced our knowledge
of biodiversity sensitivity to environmental changes,5–7 vast areas of the tropics remain understudied.8–11 In
the American tropics, Amazonia stands out as the world’s most diverse rainforest and the primary source of
Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepre sented in biodiversity databases.13–15 To worsen this situation, human-induced modifications16,17 may elim inate pieces of the Amazon’s biodiversity puzzle before we can use them to understand how ecological com munities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus
crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced
environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple or ganism groups in a machine learning model framework to map the research probability across the Brazilian
Amazonia, while identifying the region’s vulnerability to environmental change. 15%–18% of the most ne glected areas in ecological research are expected to experience severe climate or land use changes by
2050. This means that unless we take immediate action, we will not be able to establish their current status,
much less monitor how it is changing and what is being lostinfo:eu-repo/semantics/publishedVersio
Pervasive gaps in Amazonian ecological research
Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear understanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5,6,7 vast areas of the tropics remain understudied.8,9,10,11 In the American tropics, Amazonia stands out as the world's most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepresented in biodiversity databases.13,14,15 To worsen this situation, human-induced modifications16,17 may eliminate pieces of the Amazon's biodiversity puzzle before we can use them to understand how ecological communities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple organism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region's vulnerability to environmental change. 15%–18% of the most neglected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lost
Heterogeneous contributions of change in population distribution of body mass index to change in obesity and underweight NCD Risk Factor Collaboration (NCD-RisC)
From 1985 to 2016, the prevalence of underweight decreased, and that of obesity and severe obesity increased, in most regions, with significant variation in the magnitude of these changes across regions. We investigated how much change in mean body mass index (BMI) explains changes in the prevalence of underweight, obesity, and severe obesity in different regions using data from 2896 population-based studies with 187 million participants. Changes in the prevalence of underweight and total obesity, and to a lesser extent severe obesity, are largely driven by shifts in the distribution of BMI, with smaller contributions from changes in the shape of the distribution. In East and Southeast Asia and sub-Saharan Africa, the underweight tail of the BMI distribution was left behind as the distribution shifted. There is a need for policies that address all forms of malnutrition by making healthy foods accessible and affordable, while restricting unhealthy foods through fiscal and regulatory restrictions
Mortality from gastrointestinal congenital anomalies at 264 hospitals in 74 low-income, middle-income, and high-income countries: a multicentre, international, prospective cohort study
Summary
Background Congenital anomalies are the fifth leading cause of mortality in children younger than 5 years globally.
Many gastrointestinal congenital anomalies are fatal without timely access to neonatal surgical care, but few studies
have been done on these conditions in low-income and middle-income countries (LMICs). We compared outcomes of
the seven most common gastrointestinal congenital anomalies in low-income, middle-income, and high-income
countries globally, and identified factors associated with mortality.
Methods We did a multicentre, international prospective cohort study of patients younger than 16 years, presenting to
hospital for the first time with oesophageal atresia, congenital diaphragmatic hernia, intestinal atresia, gastroschisis,
exomphalos, anorectal malformation, and Hirschsprung’s disease. Recruitment was of consecutive patients for a
minimum of 1 month between October, 2018, and April, 2019. We collected data on patient demographics, clinical
status, interventions, and outcomes using the REDCap platform. Patients were followed up for 30 days after primary
intervention, or 30 days after admission if they did not receive an intervention. The primary outcome was all-cause,
in-hospital mortality for all conditions combined and each condition individually, stratified by country income status.
We did a complete case analysis.
Findings We included 3849 patients with 3975 study conditions (560 with oesophageal atresia, 448 with congenital
diaphragmatic hernia, 681 with intestinal atresia, 453 with gastroschisis, 325 with exomphalos, 991 with anorectal
malformation, and 517 with Hirschsprung’s disease) from 264 hospitals (89 in high-income countries, 166 in middleincome
countries, and nine in low-income countries) in 74 countries. Of the 3849 patients, 2231 (58·0%) were male.
Median gestational age at birth was 38 weeks (IQR 36–39) and median bodyweight at presentation was 2·8 kg (2·3–3·3).
Mortality among all patients was 37 (39·8%) of 93 in low-income countries, 583 (20·4%) of 2860 in middle-income
countries, and 50 (5·6%) of 896 in high-income countries (p<0·0001 between all country income groups).
Gastroschisis had the greatest difference in mortality between country income strata (nine [90·0%] of ten in lowincome
countries, 97 [31·9%] of 304 in middle-income countries, and two [1·4%] of 139 in high-income countries;
p≤0·0001 between all country income groups). Factors significantly associated with higher mortality for all patients
combined included country income status (low-income vs high-income countries, risk ratio 2·78 [95% CI 1·88–4·11],
p<0·0001; middle-income vs high-income countries, 2·11 [1·59–2·79], p<0·0001), sepsis at presentation (1·20
[1·04–1·40], p=0·016), higher American Society of Anesthesiologists (ASA) score at primary intervention
(ASA 4–5 vs ASA 1–2, 1·82 [1·40–2·35], p<0·0001; ASA 3 vs ASA 1–2, 1·58, [1·30–1·92], p<0·0001]), surgical safety
checklist not used (1·39 [1·02–1·90], p=0·035), and ventilation or parenteral nutrition unavailable when needed
(ventilation 1·96, [1·41–2·71], p=0·0001; parenteral nutrition 1·35, [1·05–1·74], p=0·018). Administration of
parenteral nutrition (0·61, [0·47–0·79], p=0·0002) and use of a peripherally inserted central catheter (0·65
[0·50–0·86], p=0·0024) or percutaneous central line (0·69 [0·48–1·00], p=0·049) were associated with lower mortality.
Interpretation Unacceptable differences in mortality exist for gastrointestinal congenital anomalies between lowincome,
middle-income, and high-income countries. Improving access to quality neonatal surgical care in LMICs will
be vital to achieve Sustainable Development Goal 3.2 of ending preventable deaths in neonates and children younger
than 5 years by 2030