342 research outputs found
Smart optics against smart parasites: Towards point-of-care optical diagnosis of malaria and urogenital schistosomiasis
No full textMalaria remains an important cause of high morbidity and mortality worldwide. According to World Health Organisation (WHO) malaria report for 2017, malaria accounted for the death of 435,000 people. It is the leading cause of death among pregnant women and little children. 11% of maternal and 20% of under–five deaths are attributed to malaria every year. Malaria transmission is currently active in 95 countries putting the lives of 3.2 billion people at risk. 40% of the malaria related deaths are linked to Nigeria and the Democratic republic of the Congo. Since malaria symptoms are generally non-specific and usually overlap with the symptoms of other febrile illnesses, clinical diagnosis are typically presumptive and often results into high number of false positives which potentially lead to the abuse of antimalarial drugs. The consistent abuse of antimalarial drugs has produced the consequent effect of drug resistance which is a major concern in the current global malaria control and elimination efforts. The WHO therefore recommends that an effective malaria case management plan must be predicated on a standard parasite-based confirmatory diagnostic test. Conventional light microscopy is the recommended reference diagnostic standard prescribed by the World Health Organisation. This method is particularly of interest because it allows parasite specie differentiation, quantification of the parasite density in a given blood smear, high accuracy (although this depends on the expertise of the microscopist), low direct cost, visualization of different stages of the parasite development etc. While well-equipped laboratories for malaria diagnosis are commonly available in developed urban and peri-urban areas, low-resource settings of malaria endemicity usually have very limited options. The recommended standard microscopy is less accessible in resource-limited settings because of the following: lack of required technical skills, incessant power outages, lack of efficient maintenance capability, delayed diagnosis due to intense workload, inaccuracies due to manual counting of the parasites detected in the blood film etc. The inaccuracies of parasite density estimation eventually affects the accuracy and efficiency of the prescribed treatment which could have fatal consequences. A diagnostic process is termed inconclusive by the WHO until and unless a minimum of 100 measurement (microscopy examination of 100 high powered-fields) has been done on a prepared thick blood film. For a thin blood film which provides more details about the morphology of the parasite, an average of 800 measurement is required. This is an easy task for laboratory technologist in malaria non-endemic countries where an average of 120 malaria cases occur yearly. But for malaria endemic country where several thousand cases are reported daily, this is by no means a mean task as it demands full concentration, time, high expertise and experience. To realize current global effort to reduce the heavy malaria burden, the need for a reliable, efficient, accurate and automated point-of-care diagnostic tool cannot be overemphasized. The focus of this thesis work therefore, is to develop smart optical methods that alleviate the burden of manual microscopy by researching methods to optimise existing imaging modalities which can be integrated with smart algorithms for quick malaria parasite detection in infected patients. Aside malaria, schistosomiasis is the second most common parasitic diseases. Although it falls into the category of a Neglected Tropical Disease (NTD), 220.8 million people required preventive treatment in the year 2017 according to the World Health Organisation report. It is a disease of the poor and it is prevalent in tropical and subtropical areas and particularly common in communities where there is no access to clean drinking water and proper sanitation. 779 million people are at risk of contracting this disease which results into impaired growth and development, diminished physical fitness, bladder cancer and decreased neurocognitive abilities. Although safe and effective medication is widely available for treatment, accurate diagnostic techniques for schistosomiasis is hugely underdeveloped and remains a critical challenge. Intestinal and urogenital schistosomiasis are the two variants of this Neglected tropical disease but in this research, we focus on urogenital schistosomiasis (caused by S. haemtobium) because it is most prevalent among the population we worked with and also because it is easier to detect in urine. The diagnostic protocol for S. haemtobium prescribes urine filtration with WHO recommended standard membrane filters (with 12 μl pore size). Several critical measurements by an expert must be done to detect the targeted foreign bodies (parasite eggs) in the urine samples before a reliable conclusion can be made. Also for a confirmatory diagnosis, it is standard practice to examine different samples collected from the patient at different specific intervals. This is particularly recommended to increase the amount of sample analysis per patient thereby increasing the sensitivity of the test. Since this process involves the microscopy examination of filtered urine samples, it is also limited by the challenges already described for standard malaria microscopy. Although several antigen and antibody based rapid diagnostic test kits have been developed for both malaria and schistosomiasis, the reliability of the performance of these diagnostic test is still a major concern. This thesis is aimed at the development of reliable, robust, accurate, cost effective and easy-to-use point-of-care optical devices for quick diagnosis of malaria and urogenital disease in human samples. This thesis begins by looking at light microscopy with extended depth of field. Wavefront coding with adaptive optics and digital inline holography have been considered in this work. An optimal configuration that guarantees maximum resolution based on the coherence property of illuminating source and the specification of the imaging sensor is prescribed. In this system, interference of a plane and object wave at the detector plane generates a hologram from which the complex amplitude of the field in the object plane can be numerically reconstructed by solving an inverse source problem. This method is of practical interest particularly because unlike the conventional microscope, details in transparent biological samples can be retrieved since both amplitude and the phase of the field is reconstructed. It provides potential solution towards label-free diagnosis of parasitic diseases. Combined with flow cytometry and data-driven algorithms we applied this methodology to the development of rapid detection of S. haemtobium. A working prototype device with the potential to map the diseases has been developed and tested on the field. The system design takes into consideration practical field conditions such as ease-of-use, cost, harsh environmental conditions, erratic power outages, system robustness against dust and other artifacts. Feedbacks and results from the field are very promising. Leveraging on recent advances in cellphone and 3-D printing technologies we developed an automated cell-phone based microscope towards the realization of a rapid point-of-care diagnosis of malaria. The challenge here is to optimise the optical train of a low-cost commonly available cell-phone to detect malaria parasite with sufficient resolution. It was found that existing cell-phone based microscope could not resolve the 1 µm size malaria parasites because of the system optical aberration and the numerical aperture limit of the phone objectives. Although this method demonstrate the capability of the cell phone based microscope to image malaria parasite, however the achievable field of view is limited to 150 × 150 µm. This implies that over 600 measurement is needed for a conclusive diagnosis. We circumvent this limitation by the novel implementation of computer-assisted dry fluorescent microscopy. Using computational analysis of image containing large number of blood cells, we establish a robust statistics which provides reliable diagnostic recommendation. The technique was tested with in vitro and in vivo samples and has demonstrated its suitability for highly sensitive, robust and automated diagnostics of malaria. It requires minimal human intervention, uses simple sample preparation, provides high degree of independence of expert judgement, and has a potential for massive community screening for malaria control and elimination programs. The design specifications for the development of working prototypes presented in this thesis took into account feedbacks from diagnostic experts from the following non-governmental organisations: Doctors without Borders, Malaria Consortium, AMREF, Save the Children and Christian Aid (Nigeria). Also, our methodology was thoroughly validated by discussions and interactions with experts on the field (in Nigeria, Ivory Coast, Gabon, Uganda and Ghana) and with parasitologists, researchers and vaccine developers in the Netherlands, Spain, Ireland and Germany, leading to valuable new insights.”It is our goal that the diagnostic methods and prototype presented in this thesis will be used to compliment the limitations of the existing diagnostic techniques. Team Raf Van de Pla
Optical field sampling for imaging and optical testing
No full textThis dissertation has mainly aimed at developing novel techniques, methodologies for measuring the optical field, specifically both the amplitude and phase distribution. Furthermore, we have attempted to extend their applications in the scope of optical imaging, including lensless/holographic imaging, quantitative phase imaging and the calibration for light-sheet microscopes.Team Raf Van de Pla
Extended scene deep learning wavefront sensing
No full textWe have applied a combination of blind deconvolution and deep learning to the processing of Shack-Hartmann images.By using the intensity information contained in spot positions, and the fine structure of the separate images created by the lenslets,we have increased the sensitivity and resolution of the sensor over the limit defined by standard processing of spot displacements only.We also have demonstrated the applicability of the method to wavefront sensing using extended objects as a reference. Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Team MuldersTeam Michel Verhaege
Extended Scene Deep Learning Wavefront Sensing for Real Time Image Deconvolution
No full textGround based telescope imaging suffers from interference from the earth’s atmosphere. Fluctuations in the refractive index of the air delay incoming light randomly, resulting in blurred images. A deconvolution from wavefront sensing system is an adaptive optics system that measures the modes in which the light is corrupted (i.e. the wavefront) and corrects it using a process called deconvolution. The wavefront is measured using a wavefront sensor, which consists of an array of microlenses combined with an imaging sensor. Each microlens casts an image of the object unto the imaging sensor, resulting in a collection of images that are differently aberrated depending on their location on the sensor. Conventionally, the wavefront is calculated by measuring the shifts of each microlens image and integrating these shifts over the aperture. This method, however, discards information about the higher order deformations of the microlens images. In this thesis, a novel method of wavefront reconstruction has been developed which makes use of artificial neural networks in order to extract this higher order information. In order to do this, the images produced by the microlenses are normalized, which is done using a modified version of the blind deconvolution algorithm called TIP. After the normalization, the microlens images are reduced to what they would look like if a point source was observed, instead of the object. With the influence of the object removed, an artificial neural network is used for the estimation of the wavefront. By using this method, the wavefront can be reconstructed with twice the turbulence strength compared to what is possible with conventional methods. Combining this method with an image deconvolution step results in a real-time image correction system that works up to 10Hz on the tested system, consisting of a desktop PC with an Intel Xeon E5-2630 DUAL CPU and a NVIDIA GeForce GTX 970 GPU.Mechanical Engineering | Systems and Contro
Academicianul Gleb Drăgan - savant de talie internaţională
No full textAcademicianul Gleb Drăgan a fost fondatorul Școlii de Tehnica Tensiunilor Înalte și al Laboratorului de Tehnica Tensiunilor Înalte din România. El este autorul a 33 de cărţi și coordonatorul Tratatului de Tensiuni Înalte în trei volume. El a editat 32 de dictionare explicative de terminilogie tehnică, precum și sute de studii ştiinţifice şi tehnice, articole prezentate la congrese şi conferinţe în România sau în afara ei, în special, în domeniul energetic, al descărcărilor electrice coronă, comutărilor de supratensiuni, supratensiuni atmosferice etc. De asemenea, a editat două monografii în care este descrisă tragedia familiilor basarabene deportate. Profesorul Gleb Drăgan a fost membru al Academiei Române şi al Academiei de Ştiinţe Tehnice din România, Membru Onorific al Academiei de Ştiinţe a Moldovei, Doctor Honoris Causa al Universităţii Tehnice a Moldovei şi al Universităţii Tehnice din Oradea, membru şi membru onorific în diferite organizaţii nonguvernamentale naţionale şi internaţionale.Academician Gleb Drăgan was the founder of the High Voltage Engineering School and the High Voltage Engineering Laboratory in Romania. He is the author of 33 technical books and coordinator of the High Voltage Treaty in three volumes. He edited 32 explanatory dictionaries of technical terminology, hundreds of technical and scientific studies and articles presented at congresses and conferences in the country and abroad, mainly dealing with electric power field, corona discharges, switching surges, atmospheric switching over voltages etc. He is also the author of two chronicles describing the tragedies of the deported Besssarabian families. Professor Gleb Dragan was member of the Romanian Academy and member of the Academy of Technical Sciences of Romania, Honorary Member of the Academy of Sciences of Moldova, Doctor Honoris Causa of the Technical University of Moldova and member of the Technical University of Oradea, member and honorary member in several prominent national and international non-governmental organizations
Znaczenie prochnicy dla zyznosci gleb
No full textPublikacja zawiera krótki przegląd najważniejszych prac poświęconych materii organicznej gleb, procesom humifikacji oraz wpływowi nawożenia na próchnicę; głównie prac stanowiących 40-letni dorobek naukowy Autora.This paper is a short review of some most important works concerning organic matter in soil and its transformation to humus.but mainly it is the review of the projects which the Author has been doing during forty years of his work on this subject
Prawna ochrona zdolności produkcyjnej gleb – zagadnienia wybrane
No full textThe subject of the article is the legal aspects of protecting the productive capacity of soils. The study is of a scientific and research nature. The author starts from the statement that soils perform, in particular, environmental, economic, social and cultural functions, while for the protection of the characteristics that determine the possibility of using soils in food production, production functions, combined with the production function of agriculture, are important. Thus, the purpose of the analysis is to determine whether current Polish legislation sufficiently takes into account the need to protect the productive capacity of soils, understood as the possibility of sustainable use of these resources for food production. Consideration of this issue leads to the conclusion that the current legislation does not sufficiently take into account the need to protect the productive functions of soils, while a certain degree of protection is assumed by draft EU legislation on, among other things, soil monitoring granting Member States a significant role in tracking, assessing and managing the condition of soils.Przedmiotem badania w artykule są prawne aspekty ochrony zdolności produkcyjnej gleb. Opracowanie ma charakter naukowo-badawczy. Autorka wychodzi od stwierdzenia, że gleby pełnią zwłaszcza funkcje środowiskowe, gospodarcze, społeczne i kulturowe, a z punktu widzenia ochrony cech warunkujących możliwość wykorzystania gleb w produkcji żywności ważna są funkcje produkcyjne, łączące się z funkcją produkcyjną rolnictwa. Celem analizy jest ustalenie, czy obowiązujące polskie prawodawstwo dostatecznie uwzględnia potrzebę ochrony zdolności produkcyjnej gleb, rozumianej jako możliwość zrównoważonego wykorzystywania tych zasobów do produkcji żywności. Rozważania nad tym zagadnieniem prowadzą do wniosku, że tak nie jest, natomiast pewien zakres ochrony zakładają projekty unijnych aktów prawnych, m.in. w sprawie monitorowania gleb, przyznający państwom członkowskim znaczącą rolę w śledzeniu i ocenie stanu gleb oraz zarządzaniu nimi
Adaptive Optics with Curvature Wavefront Sensor
No full textWhen acquiring information using imaging techniques, one wants to achieve the best possible resolution in order to obtain valuable results. In the ideal scenario the size of the smallest resolved object features is limited by the wave properties of light, with a number of techniques developed to overcome this limit. In real life measurements the image quality is additionally deteriorated by the non-uniformities in refractive index along the beam propagation path, called aberrations. Adaptive Optics, introduced in 1950’s independently by Horace Babcock and Vladimir Linnik is a set of methods used to overcome the effect of aberrations and thus improve the image quality. Initially used in military applications for tracking satellites, it later found civilian applications as advances in computing made it practical.Adaptive Optics use principles of feedback control to correct aberrations, and thus a measurement of controlled variable is required. The most commonly measured quantity is first derivative of wavefront provided by the Shack-Hartmann sensor. Another possibility is to measure wavefront Laplacian, i.e. curvature, using the sensor proposed by Roddier in 1988. With the correct use of this sensor the deformable mirror actuators are decoupled from each other, enabling fast and accurate control of high order systems and potentially analog feedback loop.In this thesis, the Roddier curvature wavefront sensor is studied. A number of modifications in the original sensor geometry and operating principles are made in order to make the system more robust and easy to implement in laboratory environment. Performance of the modified curvature wavefront sensor is evaluated in both simulation environment and physical setup.Finally, application of the curvature sensor to measure wind velocity is demonstrated.Mechanical Engineering | Systems and Contro
Automating malaria diagnosis: a machine learning approach: Erythrocyte segmentation and parasite identification in thin blood smear microscopy images using convolutional neural networks
No full textReliable malaria diagnosis techniques that are suitable for point-of-care testing in high burden areas, are vital for effective treatment and monitoring of the disease. Identification of malaria parasites in Giemsa stained blood slides is currently the most widely accepted technique, but its availability is limited by the need for highly trained experts to interpret the data.In this work, a two stage automated image classification strategy is proposed, to eliminate this dependency on human expertise. Blood slides that were photographed at 20 X magnification were used in our experiments, allowing for a larger Field of View than regular thin film microscopy at 100 X. Erythrocytes are first localised and segmented by a Convolutional Neural Network, the architecture of which is based on U-Net, with some adaptations and improvements made for our purposes. The sensitivity and positive predictive value of the localisation were both 0.998, resulting in accurate cell counts.A transfer learning strategy, in which the existing VGG-16 network is used as a feature extractor and combined with a new fully connected layer to predict correct activations for our classification, is then used to classify the segmented erythrocytes as either infected with Plasmodium Falciparum parasite or healthy. Sensitivity and specificity of the predicted classification were 0.795 and 0.915 respectively. It is concluded that, although this method may not fully eliminate the need for trained experts, the algorithms proposed can be of great assistance in aiding the diagnostic decision making process.Mechanical Engineering | Systems and Contro
The Medieval Russian Library (II) : Tales about Boris and Gleb
No full textThe author in this bulletine provides translations of three literary works supposed to have been created from the latter half of 11th century to the first half of 12th, which concerned the murders of the princes of Rus’(the old name of Russia) Boris and Greb. The names of the works are “The Tale and Passion and Panegyrcis to the Holy Matyrs Boris and Gleb”, “The Tales of the Miracles of the Holy Passion bearers Roman and David” and “Lesson concerning the Life and Assassination of the Blessed Passionbearers Boris and Gleb”. The murders occurred in 1015, when their father Vladimir died. Vladimir had converted Rus’into Christianity in 988. After his death the struggle for the kievan grand princedom started. The senioir son, so called “cursed” Sviatopolk, seized Kiev by force. But Sviatopolk, who was not satisfied by the occupation of the kievan princedom, undertook the erasure of his rivals, that is, his younger brothers Boris and Gleb. Boris and Gleb, who knew the malice of Sviatopolk, did not make any resistance against their elder brother and were killed. Because of their nonresistance and the respect for the family seniority Boris and Gleb were later kanonized as the first Christian saints in Rus’. The above-metioned three tales deal with this tragic political affair in the dawn of the Russian Orthodox Christianity.departmental bulletin pape
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