Optical fibre sensors for novel medical devices during anaesthesia

This research focuses on the development of optical fibre sensors that can be applied during critical care. The sensors developed are: (i) an optical fibre humidity sensor based on the deposition of a hygroscopic film onto the distal tip of the fibre and forming a Fabry-Pêrot cavity; (ii) chemical functionalization of U-shaped fibres and Long Period Gratings (LPGs). Fibre Bragg Gratings (FBGs) are only used for temperature monitoring in this work. The current trends in a new generation of humidity sensors suggest that electronic-based technologies could be soon replaced by photonic sensors due to better response times. Optical fibre technology has been considered as a promising platform for providing engineering solutions to unmet clinical needs. For example, anaesthetized patients are transferred from the induction room to the MRI room and taken back, with the need for continuous monitoring of vital signs such as respiration, but some technologies lack compatibility with MRI fields. In the operating room, patients are under anaesthesia, intubated and mechanically ventilated, but some under-humidification or over-humidification of the ventilation air causes secondary effects. Anaesthesiologists rely on total intravenous anaesthesia (TIVA) and monitoring of vital signs as indicators of unconsciousness; current investigations have shown that there is a need to measure the concentration of propofol in real time directly from the blood or breath of patients. Similarly, patients in the intensive care unit (ICU) after surgery require continuous monitoring of diverse biochemical parameters. In this research, the application of optical fibre sensors is demonstrated as an engineering solution for some of these clinical challenges. The simultaneous measurement of humidity and temperature with an optical fibre sensor, a biosensor for propofol detection and another for protein detection were fabricated and demonstrated in this work. The sensitivity, response time and hysteresis of a novel optical fibre humidity sensor has been investigated over a humidity range of 5% Relative Humidity (RH) to 95% RH using a controlled bench-top set-up. The optical fibre humidity sensor proposed has a very simple and low cost porous structured sensing element obtained with poly(allylamine hydrochloride) (PAH) and silica (SiO2) using the layer-by-layer (LbL) fabrication method. The fast response of the sensor (1.13 ± 0.3 s) enabled changes in humidity in individual breaths to be resolved. After calibration, the performance of the sensor was evaluated in the breathing circuit of a mechanical ventilator and respiratory equipment where its faster response allowed monitoring of breath to breath humidity levels during different modes of ventilation. It also has the capability to provide absolute humidity (AH) measurements when an FBG is included for simultaneous temperature measurements. An LPG sensor anchored with SiO2 core and gold (Au) shell nanoparticles has been investigated as a biosensing platform for protein detection. The well-known protein interaction between biotin and streptavidin (SV) was used as a proof of concept. The proposed sensor presented Langmuir adsorption to SV concentrations with a limit of detection (LoD) down to 15.13 nM and a lowest detected concentration of 2.5 nM. In addition, U-shaped fibres and LPGs functionalized with host-guest imprinted TiO2 thin films were used to test propofol detection in aqueous solutions. These sensors also presented Langmuir adsorption in the mili-molar range in aqueous solutions and a lowest detected concentration of 0.65 uM. Detection limits of propofol were improved with the addition of mesoporous silica nanoparticles (MSNs) and inorganic molecular imprinting to allow detection down to 99 nM in aqueous solution and 30 ppb in gaseous phase. In conclusion, this research has successfully demonstrated the use of novel optical fibre sensors in laboratory and real conditions through embedding the developed sensors in critical care equipment usually used during anaesthesia

Additional information delivery to image content via improved unseen–visible watermarking

In a practical watermark scenario, watermarks are used to provide auxiliary information; in this way, an analogous digital approach called unseen–visible watermark has been introduced to deliver auxiliary information. In this algorithm, the embedding stage takes advantage of the visible and invisible watermarking to embed an owner logotype or barcodes as watermarks; in the exhibition stage, the equipped functions of the display devices are used to reveal the watermark to the naked eyes, eliminating any watermark exhibition algorithm. In this paper, a watermark complement strategy for unseen–visible watermarking is proposed to improve the embedding stage, reducing the histogram distortion and the visual degradation of the watermarked image. The presented algorithm exhibits the following contributions: first, the algorithm can be applied to any class of images with large smooth regions of low or high intensity; second, a watermark complement strategy is introduced to reduce the visual degradation and histogram distortion of the watermarked image; and third, an embedding error measurement is proposed. Evaluation results show that the proposed strategy has high performance in comparison with other algorithms, providing a high visual quality of the exhibited watermark and preserving its robustness in terms of readability and imperceptibility against geometric and processing attacks

Real-Time Humidity Measurement during Sports Activity using Optical Fibre Sensing

An optical fibre sensor for monitoring relative humidity (RH) changes during exercise is demonstrated. The humidity sensor comprises a tip coating of poly (allylamine hydrochloride) (PAH)/silica nanoparticles (SiO2 NPs) deposited using the layer-by-layer technique. An uncoated fibre is employed to compensate for bending losses that are likely to occur during movement. A linear fit to the response of the sensing system to RH demonstrates a sensitivity of 3.02 mV/% (R2 = 0.96), hysteresis ± 1.17% RH when 11 bilayers of PAH/SiO2 NPs are coated on the tip of the fibre. The performance of two different textiles (100% cotton and 100% polyester) were tested in real-time relative humidity measurement for 10 healthy volunteers. The results demonstrate the moisture wicking properties of polyester in that the relative humidity dropped more rapidly after cessation of exercise compared to cotton. The approach has the potential to be used to monitor sports performance and by clothing developers for characterising different garment designs

Effect of Boriding on the Mechanical Properties of AISI 1045 Steel

Efecto en las propiedades mecánicas de un acero borurado 1045.Some mechanical properties of AISI 1045 borided steels were estimated in the present work. The boriding process was carried out by the powder pack method at 950°C with 8 h of treatment. The fatigue strength on borided notched specimens was evaluated with rotating bending tests (R=1) considering a stress concentration factor (Kt) of 2.53. Likewise, the presence of residual stresses in boride layers was established by the XRD technique. The Daimler-Benz Rockwell C test was used, also, to estimate the strength adhesion of the coated system. The results show a decrease in the fatigue strength of AISI borided steels due to the presence of high porosity in the layers. Finally, the Rockwell-C adhesion test showed no coating failure for the boride layer

Hyperspectral imaging benchmark based on machine learning for intraoperative brain tumour detection

publishedVersio

Calidad de las elecciones a titular del Ejecutivo en el Centro y Centro-occidente de México

Este libro, que tiene por objetivo analizar la calidad de las elecciones celebradas entre 2006 y 2011 para ocupar la titularidad del Poder Ejecutivo de las 14 entidades federativas de la República Mexicana que conforman las regiones Centro y Centro-occidente de este país, ha sido elaborado por investigadores pertenecientes a la Red Nacional de Investigación sobre la Calidad de la Democracia en México (Renicadem), la cual cuenta con un equipo de investigación en cada una de las entidades federativas del país. A su vez, esta Red constituye una de las cuatro líneas temáticas que componen la red temática del Conacyt “Sociedad civil y calidad de la democracia”. Con todo, la presente obra puede considerarse, en dos sentidos, como el resultado parcial de estudios realizados por investigadores que conforman la mencionada Renicadem. Por un lado, trata sólo de una de las varias dimensiones que esta Red ha establecido como necesarias para analizar la calidad de la democracia: la calidad electoral (otras dimensiones, que se encuentran en proceso de investigación, son calidad de vida, rendición de cuentas y Estado de derecho). También es parcial porque no abarca la totalidad de la República Mexicana, sino únicamente a las 14 entidades indicadas.UAE

Impact of COVID-19 on cardiovascular testing in the United States versus the rest of the world

Objectives: This study sought to quantify and compare the decline in volumes of cardiovascular procedures between the United States and non-US institutions during the early phase of the coronavirus disease-2019 (COVID-19) pandemic. Background: The COVID-19 pandemic has disrupted the care of many non-COVID-19 illnesses. Reductions in diagnostic cardiovascular testing around the world have led to concerns over the implications of reduced testing for cardiovascular disease (CVD) morbidity and mortality. Methods: Data were submitted to the INCAPS-COVID (International Atomic Energy Agency Non-Invasive Cardiology Protocols Study of COVID-19), a multinational registry comprising 909 institutions in 108 countries (including 155 facilities in 40 U.S. states), assessing the impact of the COVID-19 pandemic on volumes of diagnostic cardiovascular procedures. Data were obtained for April 2020 and compared with volumes of baseline procedures from March 2019. We compared laboratory characteristics, practices, and procedure volumes between U.S. and non-U.S. facilities and between U.S. geographic regions and identified factors associated with volume reduction in the United States. Results: Reductions in the volumes of procedures in the United States were similar to those in non-U.S. facilities (68% vs. 63%, respectively; p = 0.237), although U.S. facilities reported greater reductions in invasive coronary angiography (69% vs. 53%, respectively; p < 0.001). Significantly more U.S. facilities reported increased use of telehealth and patient screening measures than non-U.S. facilities, such as temperature checks, symptom screenings, and COVID-19 testing. Reductions in volumes of procedures differed between U.S. regions, with larger declines observed in the Northeast (76%) and Midwest (74%) than in the South (62%) and West (44%). Prevalence of COVID-19, staff redeployments, outpatient centers, and urban centers were associated with greater reductions in volume in U.S. facilities in a multivariable analysis. Conclusions: We observed marked reductions in U.S. cardiovascular testing in the early phase of the pandemic and significant variability between U.S. regions. The association between reductions of volumes and COVID-19 prevalence in the United States highlighted the need for proactive efforts to maintain access to cardiovascular testing in areas most affected by outbreaks of COVID-19 infection

Global, regional, and national under-5 mortality, adult mortality, age-specific mortality, and life expectancy, 1970–2016: a systematic analysis for the Global Burden of Disease Study 2016

BACKGROUND: Detailed assessments of mortality patterns, particularly age-specific mortality, represent a crucial input that enables health systems to target interventions to specific populations. Understanding how all-cause mortality has changed with respect to development status can identify exemplars for best practice. To accomplish this, the Global Burden of Diseases, Injuries, and Risk Factors Study 2016 (GBD 2016) estimated age-specific and sex-specific all-cause mortality between 1970 and 2016 for 195 countries and territories and at the subnational level for the five countries with a population greater than 200 million in 2016. METHODS: We have evaluated how well civil registration systems captured deaths using a set of demographic methods called death distribution methods for adults and from consideration of survey and census data for children younger than 5 years. We generated an overall assessment of completeness of registration of deaths by dividing registered deaths in each location-year by our estimate of all-age deaths generated from our overall estimation process. For 163 locations, including subnational units in countries with a population greater than 200 million with complete vital registration (VR) systems, our estimates were largely driven by the observed data, with corrections for small fluctuations in numbers and estimation for recent years where there were lags in data reporting (lags were variable by location, generally between 1 year and 6 years). For other locations, we took advantage of different data sources available to measure under-5 mortality rates (U5MR) using complete birth histories, summary birth histories, and incomplete VR with adjustments; we measured adult mortality rate (the probability of death in individuals aged 15-60 years) using adjusted incomplete VR, sibling histories, and household death recall. We used the U5MR and adult mortality rate, together with crude death rate due to HIV in the GBD model life table system, to estimate age-specific and sex-specific death rates for each location-year. Using various international databases, we identified fatal discontinuities, which we defined as increases in the death rate of more than one death per million, resulting from conflict and terrorism, natural disasters, major transport or technological accidents, and a subset of epidemic infectious diseases; these were added to estimates in the relevant years. In 47 countries with an identified peak adult prevalence for HIV/AIDS of more than 0·5% and where VR systems were less than 65% complete, we informed our estimates of age-sex-specific mortality using the Estimation and Projection Package (EPP)-Spectrum model fitted to national HIV/AIDS prevalence surveys and antenatal clinic serosurveillance systems. We estimated stillbirths, early neonatal, late neonatal, and childhood mortality using both survey and VR data in spatiotemporal Gaussian process regression models. We estimated abridged life tables for all location-years using age-specific death rates. We grouped locations into development quintiles based on the Socio-demographic Index (SDI) and analysed mortality trends by quintile. Using spline regression, we estimated the expected mortality rate for each age-sex group as a function of SDI. We identified countries with higher life expectancy than expected by comparing observed life expectancy to anticipated life expectancy on the basis of development status alone. FINDINGS: Completeness in the registration of deaths increased from 28% in 1970 to a peak of 45% in 2013; completeness was lower after 2013 because of lags in reporting. Total deaths in children younger than 5 years decreased from 1970 to 2016, and slower decreases occurred at ages 5-24 years. By contrast, numbers of adult deaths increased in each 5-year age bracket above the age of 25 years. The distribution of annualised rates of change in age-specific mortality rate differed over the period 2000 to 2016 compared with earlier decades: increasing annualised rates of change were less frequent, although rising annualised rates of change still occurred in some locations, particularly for adolescent and younger adult age groups. Rates of stillbirths and under-5 mortality both decreased globally from 1970. Evidence for global convergence of death rates was mixed; although the absolute difference between age-standardised death rates narrowed between countries at the lowest and highest levels of SDI, the ratio of these death rates-a measure of relative inequality-increased slightly. There was a strong shift between 1970 and 2016 toward higher life expectancy, most noticeably at higher levels of SDI. Among countries with populations greater than 1 million in 2016, life expectancy at birth was highest for women in Japan, at 86·9 years (95% UI 86·7-87·2), and for men in Singapore, at 81·3 years (78·8-83·7) in 2016. Male life expectancy was generally lower than female life expectancy between 1970 and 2016, an

Optical fibre sensors for novel medical devices during anaesthesia

This research focuses on the development of optical fibre sensors that can be applied during critical care. The sensors developed are: (i) an optical fibre humidity sensor based on the deposition of a hygroscopic film onto the distal tip of the fibre and forming a Fabry-Pêrot cavity; (ii) chemical functionalization of U-shaped fibres and Long Period Gratings (LPGs). Fibre Bragg Gratings (FBGs) are only used for temperature monitoring in this work. The current trends in a new generation of humidity sensors suggest that electronic-based technologies could be soon replaced by photonic sensors due to better response times. Optical fibre technology has been considered as a promising platform for providing engineering solutions to unmet clinical needs. For example, anaesthetized patients are transferred from the induction room to the MRI room and taken back, with the need for continuous monitoring of vital signs such as respiration, but some technologies lack compatibility with MRI fields. In the operating room, patients are under anaesthesia, intubated and mechanically ventilated, but some under-humidification or over-humidification of the ventilation air causes secondary effects. Anaesthesiologists rely on total intravenous anaesthesia (TIVA) and monitoring of vital signs as indicators of unconsciousness; current investigations have shown that there is a need to measure the concentration of propofol in real time directly from the blood or breath of patients. Similarly, patients in the intensive care unit (ICU) after surgery require continuous monitoring of diverse biochemical parameters. In this research, the application of optical fibre sensors is demonstrated as an engineering solution for some of these clinical challenges. The simultaneous measurement of humidity and temperature with an optical fibre sensor, a biosensor for propofol detection and another for protein detection were fabricated and demonstrated in this work. The sensitivity, response time and hysteresis of a novel optical fibre humidity sensor has been investigated over a humidity range of 5% Relative Humidity (RH) to 95% RH using a controlled bench-top set-up. The optical fibre humidity sensor proposed has a very simple and low cost porous structured sensing element obtained with poly(allylamine hydrochloride) (PAH) and silica (SiO2) using the layer-by-layer (LbL) fabrication method. The fast response of the sensor (1.13 ± 0.3 s) enabled changes in humidity in individual breaths to be resolved. After calibration, the performance of the sensor was evaluated in the breathing circuit of a mechanical ventilator and respiratory equipment where its faster response allowed monitoring of breath to breath humidity levels during different modes of ventilation. It also has the capability to provide absolute humidity (AH) measurements when an FBG is included for simultaneous temperature measurements. An LPG sensor anchored with SiO2 core and gold (Au) shell nanoparticles has been investigated as a biosensing platform for protein detection. The well-known protein interaction between biotin and streptavidin (SV) was used as a proof of concept. The proposed sensor presented Langmuir adsorption to SV concentrations with a limit of detection (LoD) down to 15.13 nM and a lowest detected concentration of 2.5 nM. In addition, U-shaped fibres and LPGs functionalized with host-guest imprinted TiO2 thin films were used to test propofol detection in aqueous solutions. These sensors also presented Langmuir adsorption in the mili-molar range in aqueous solutions and a lowest detected concentration of 0.65 uM. Detection limits of propofol were improved with the addition of mesoporous silica nanoparticles (MSNs) and inorganic molecular imprinting to allow detection down to 99 nM in aqueous solution and 30 ppb in gaseous phase. In conclusion, this research has successfully demonstrated the use of novel optical fibre sensors in laboratory and real conditions through embedding the developed sensors in critical care equipment usually used during anaesthesia