251 research outputs found
Clinical and experimental implementation of standardized hypothermic treatment for neonatal asphyxia in low-income settings [Elektronisk resurs]
No full textBackground: Hypoxic ischemic encephalopathy (HIE) is a potentially devastating condition caused by birth asphyxia. The standard of care for infants with moderate and severe HIE is therapeutic hypothermia (TH), initiated within six hours after delivery. This intervention improves survival rates and reduces long- term neurological disabilities. Despite its efficacy in high-income countries, the implementation of TH faces significant challenges in low- and middle-income settings, including a lack of evidence supporting its benefits, inadequate high- cost cooling equipment, and insufficient long-term outcome predictive markers and evaluations. Aims: The overall aim of this thesis was to develop and evaluate novel equipment for counteracting hypoxic-ischemic brain injuries in newborns in low- and middle-income countries. The specific aims included: To evaluate the application of phase changing material (PCM) for induction of TH in infants with moderate- severe HIE in a tertiary setting and during inter-hospital transportation, in order to enhance the therapeutic effects of TH (Studies I & II) and to determine neurological and neurodevelopmental outcomes for infants treated with TH in low- and middle-income settings (Study III). An additional aim was to evaluate early predictors of outcome of asphyxiated newborns transported for TH, by measuring levels of blood lactated dehydrogenase (LDH) activity and monitoring brain function with amplitude-integrated EEG (aEEG) (Study IV). Materials and methods: One pilot observational study (Study I) and one clinical trial (Studies II-IV) were conducted in Hanoi, Vietnam, between 2014 and 2019. The studies involved neonates born in the northern regions of Vietnam with HIE and requiring TH. The primary outcomes were short-term outcomes of HIE and medium-term outcomes. In study IV, the predictive values of high LDH (>1000 U/L) and severely depressed aEEG were evaluated. Results: Studies I and II showed that, despite not being a servo-controlled device, the PCM mattress effectively cooled and maintained infants’ body temperatures at more than 80% of the 72-hour treatment period with little nursing intervention, a significant advantage in resource-limited settings. When used during inter- hospital transportation, PCM as compared to passive cooling did not improve short-term outcomes. However, PCM was a safe and effective piece of equipment for transport of babies eligible for TH and reduced the time to achieve the target temperature for TH. Follow-up at 18 months showed that infants who received TH 67% survived, and, among the survivors, 60% demonstrated normal development or only mild delays in movement and cognition. The remaining survivors exhibited severe neurological disorders, such as cerebral palsy or epilepsy. Study III showed that these serious sequelae can be identified early in the post-natal period using simple screening tools like the Ages and Stages Questionnaires and the Hammersmith Infant Neurological Examination with high sensitivity and specificity. In Study IV, we also found that biological and imaging markers can predict outcomes early, including lactate dehydrogenase (LDH) and early aEEG. Conclusion: The studies presented in this PhD thesis demonstrate the effectiveness of a mattress made of PCM as a low-cost cooling method for TH of infants with moderate to severe HIE in low- and middle-income countries. A majority of the infants treated with TH had favorable outcomes, with many surviving and developing normally or with only mild delays. Early identification of neurological sequelae through simple screening tools and early biomarkers aids clinicians in improving prognosis and treatment decisions for HIE babies
HIV-1 genotype and vertical transmission in northern Vietnam [Elektronisk resurs]
No full textAfter 18 years from the beginning of the HIV-1/AIDS epidemic in Vietnam, the number of HIV-1 infected individuals is still increasing. Investigations conducted at two distinct time points in two separate groups of HIV-1 infected intravenous drug users (IDUs) and pregnant women in Northern Vietnam indicated that the HIV-1 CRF01_AE genotype is dominating in Northern Vietnam. Our analysis was based on 399 gp120 V3 env sequences comprising HIV-1 strains studied by us and on previously published Vietnamese sequences and on reference sequences from neighboring countries available in the Los Alamos HIV database. By using different softwares to determine the phylogenetic relationship of the different HIV-1 strains, we showed that the HIV-1 CRF01_AE present in Northern Vietnam is closely related with the HIV-1 CRF01_AE sequences from Southern China, whereas HIV-1 CRF01_AE sequences from Southern Vietnam have a closer link with HIV-1 CRF01_AE Thailand sequences. The genetic analysis of the gp120 V3 env sequences obtained from HIV-1 infected IDUs in 2002 and pregnant women in 2006-2007 revealed that HIV-1 is spreading rapidly in Northern Vietnam. The fast spreading epidemic can be identified by the low level of variation noticed in HIV-1 strains infecting IDUs and pregnant women in Northern Vietnam. HIV-1 infection in pregnant women is increasing in Vietnam. Several prevention programs have however been started to control HIV-1 vertical transmission in Northern Vietnam. In my study 182 HIV-1 infected mothers and their children were enrolled. The HIV-1 infection in children was confirmed by the presence of the HIV-1 pol gene in blood cell DNA. The PCR was performed from birth until 12 months and HIV-1 serology from 12 to 18 months. The total HIV-1 transmission rate to the children in our study was 6.7% with a rate of pre-partum transmission of 4.2% and intra-partum transmission of 1.5%. About 60% of the HIV-1 infected mothers received one dose of nevirapine at labor. The children were treated with liquid nevirapine within 48 hours from birth. In addition, ARV combination was provided to 11% of the HIV-1 pregnant women for a few weeks prior to delivery and zidovudine was given to the children one week after birth. Through counselling, the women were convinced to not breast-feed their infants. It was documented that there was no evidence of postpartum transmission. The key for the prevention of HIV-1 transmission from mother to child is counselling and this procedure needs to be further implemented in Vietnam. The different HIV-1 subtypes might have a different response to the anti retroviral treatment. In order to evaluate this possibility we measured the changes of sCD27 levels in plasma in patients infected with HIV-1 subtypes A, or B, or C or D and treated with ART for 12 months. The sCD27 is a marker of immune activation. The data showed that sCD27 is considerably higher (p<0.001) in the HIV-1 infected group than in the control group. After 12 months of treatment, the reduction of sCD27 levels in plasma was significant for all HIV-1 subtypes (p<0.001) with the largest reduction for HIV-1 subtype C. Our results suggest that a significant reduction in immune activation could be measured after 1 year of ART for all the different subtypes; thus sCD27 can be considered as a relevant immune marker to measure response to therapy
Probing Higgs width and top quark Yukawa coupling from ttH and tttt productions
No full textWe demonstrate that four top-quark production is a powerful tool to constrain the top Yukawacoupling. The constraint is robust in the sense that it does not rely on the Higgs boson decay. Taking into account the projection of the ttH production by the ATLAS Collaboration, we obtained a bound on the Higgs boson width, GH <= 2.57G(H)(SM), at the 14 TcV Large Hadron Collider with an integrated luminosity of 300 fb(-1).National Science Foundation of China [11175069, 11275009, 11675002, 11635001, 11422545]SCI(E)ARTICLE59
Patients with tension-type headaches feel stigmatized
No full textThe author, a sufferer of tension-type headache (TTH), believes that the word "tension" in "tension-type headache" carries a social stigma and that patients do not accept a diagnosis of TTH readily. TTH is the most common primary headache disorder. The disability of TTH as a burden of society is greater than that of migraine. Absenteeism because of TTH is higher than that due to migraine. However, patients with TTH do not go for consultation. Even the prevalence of new daily persistent headache (NDPH) is 12 times higher at the headache clinic than that of chronic TTH (CTTH). These points hint that TTH patients probably do not want to visit the clinic. The author believes that it could be because of the stigma attached to "tension." Herein, the author has noted the first responses given by 50 consecutive patients with TTH when they were told that they had been suffering from TTH. The first answer of 64% of patients with TTH was "I do not have any tension/stress ." This denial is similar to the denial declared by patients with depression. Depression and tension are similar in the sense that both are considered as a signs of personal weakness. Such a preconception in the society creates a stigma, and patients deny the diagnosis, conceal symptoms, and become reluctant to seek help and treatment
Depression and associated factors among infertile women at Tu Du hospital, Vietnam: a cross-sectional study
No full textTuan M Vo,1 Quynh TT Tran,2 Cuong V Le,3 Trang TH Do,4 Thi M Le51Department of Obstetrics and Gynecology, University of Medicine and Pharmacy at Ho Chi Minh City, Ho Chi Minh City, Vietnam; 2Department of General Gynecology, Tu Du Hospital, Ho Chi Minh City, Vietnam; 3The Science and Technology Office, University of Medicine and Pharmacy at Ho Chi Minh City, Ho Chi Minh City, Vietnam; 4Department of Disaster Management, Hanoi University of Public Health, Hanoi, Vietnam; 5Department of Population and Reproductive Health, Hanoi University of Public Health, Hanoi, VietnamBackground: About 40,000 infertile couples visit Tu Du Hospital, Vietnam for consultation and treatment of infertility per year. Depression in infertile female patients not only influences mental wellbeing, but also affects the effectiveness of infertility treatment. The study aimed to determine the depression prevalence in infertile female patients and associated factors.Methods: A cross-sectional study was conducted during April–July 2016 with 401 infertile women visiting the Department of Infertility at Tu Du Hospital . The PHQ-9 scale was used to measure depressive symptoms. Face-to-face interviewing was conducted using a structured questionaire. Participants were also inquired about demographic characteristics, socio-economic status, infertility related characteristics and family and social relationships.Results: The depression prevalence was 12.2%, with a cut-off score ≥10 on PHQ-9 scale. Depression in infertile female patients was associated with infertility caused by the husband (AOR=3.09, 95% CI=1.44–6.63), infertility caused by both spouses (AOR=3.63, 95% CI=1.26–10.48), alcohol-addicted husband (AOR=4.83, 95% CI=1.32–17.58), and with wife’s previous antidepressant use (AOR=48.1, 95% CI=4.83–47.96)Conclusions: Assessment of depressive symptoms should be assessed at an early stage among infertile female patients for timely mental health support.Keywords: infertile female patient, depression, PHQ-
Recherche du Boson de Higgs dans le canal ttH(H->bb) et l'identification des jets contenant deux Hadrons B avec l'experience ATLAS.
No full textObserving the Higgs boson production in association with a pair of top quarks (ttH)would allow a direct measurement of the top quark Yukawa coupling and provides animportant test of the Higgs mechanism within the SM. This thesis presents a searchfor the Higgs boson in the ttH(H->bb) channel using proton-proton collisions at13 TeV, collected with the ATLAS detector in 2015 and 2016. The Higgs boson decays to two b quarks and top quark pair decays with one lepton, the ttH->(lνb)(jjb)(bb)single lepton channel, are considered.This document details in particular the contributions made by the author in thissearch: the full reconstruction of the ttH(H->bb) single lepton system and the final discrimination between signal and the main background, tt +jets. A new methodwas developed to solve the large combinatorial background by fully reconstructing thettH(H->bb) final state using a multivariate technique to uniquely associate each reconstructed jets to the initial quarks. A multivariate technique was also used to discriminatebetween the signal and the main tt+jets background further increasing the sensitivityof the search compared to the Run 1 analysis. Finally, the first result at 13 TeV isshown. The signal strength (the ratio between the measured and predicted cross sections) is found to be 1.6 ± 1.1. No significant excess of events above the backgroundexpectation is found and an observed (expected) limit of 3.6 (2.2) is set at 95% confidence level.ResumeEn juillet 2012, le CERN a annoncé la découverte du boson de Higgs qui est la dernière particule manquante du Modèle Standard. Le boson de Higgs observé montre un couplage directe au bosons W, Z et au lepton tau et indirect au quark top. Afin de vérifier s’il s’agit bien du boson de Higgs du Modèle Standard ou d’un modèle alternatif, les couplages directs du boson de Higgs au quarks doivent également être mesurés et comparés aux prédictions du Modèle Standard.La recherche du boson de Higgs produit en association avec une paire de quarks top (t ̄tH) est le seul moyen pour accéder directement au couplage de Yukawa du boson de Higgs au quark top. Cette measure fournit un test important du mécanisme de Higgs dans le Modèle Standard. Cette thèse présente une recherche du boson de Higgs dans le canal t ̄tH (H→b ̄b), en utilisant les données de collisions proton-proton à √s= 13TeV, collectées avec le détecteur ATLAS en 2015 et 2016. Le canal considéré est t ̄tH(H→(lνb)(jjb)(b ̄b), le boson de Higgs se désintégrant en deux quarks b et l’un des quarks top se désintégrant avec en lepton
COVID-19 initial preparedness and response in Vietnam during the first six months of the pandemic and the lessons for Sendai framework implementation
No full texturpose
This paper aims to analyze the current responses applied in Vietnam to the Coronavirus disease (COVID-19) pandemic and link these measures to priority actions highlighted in the Sendai Framework for Disaster Risk Reduction (SFDRR). From there, strengths, limitations and recommendations on applying the SFDRR to build the pandemic resilience in the future are discussed.
Design/methodology/approach
The authors synthesize literature on response measures to the COVID-19 pandemic in Vietnam from January to June 2020 and compare to four priority actions of the SFDRR including understanding risk, strengthening governance, investing in risk reduction for resilience and enhancing preparedness for effective response and resilient recovery.
Findings
Vietnam has effectively controlled the pandemic with 401 infected cases and no death so far. Well preparation, timely policies’ implementation, risk communication and comprehensive approaches are key strategies. These measures are same as the four priority actions in the SFDRR.
Originality/value
To the best of the authors’ knowledge, this is the first study in Vietnam to link the COVID-19 response and the SFDRR, which can serve as an important example for other countries in responding to the pandemic. Some measures have surpassed SFDRR’s guidance, especially preventive responses applied nationwide with strong political will and the community’s commitment accompanied by sanctions. Cultural factors such as the habit of using masks to prevent air pollution have contributed to the good observance of wearing mask regulations during the pandemic. However, some areas that need more attention include specific solutions for vulnerable groups, limiting fake news and ensuring patient privacy.Full Tex
CFD model-supported design of monodisperse co-current spray dryers
No full text[EN] In this study the operation of spray drying chambers fitted by the multi-stream monodisperse atomizer was simulated by the previously developed CFD model of skim milk spray drying. A series of CFD simulations of skim milk monodisperse spray drying were performed. The influence of different nozzle positions, initial droplet diameters (180 μm and 167 μm) and the way of air introduction (vertical or swirling with 30° or 60° angle) on the drying process were checked. Parameters like drying air and particle residence time, wall deposition, inter-particle collisions, protein thermal deactivation, air velocity and temperature profiles were compared for each case.The research leading to these results has received funding from the European Union’s Seventh Framework Programme for research, technological development and demonstration under grant agreement n°613732 – project ENTHALPY.Jaskulski, M.; Tran, TTH.; Tsotsas, E. (2018). CFD model-supported design of monodisperse co-current spray dryers. En IDS 2018. 21st International Drying Symposium Proceedings. Editorial Universitat Politècnica de València. 213-220. https://doi.org/10.4995/IDS2018.2018.7274OCS21322
Recherche du boson de Higgs dans le canal ttH (H->bb) avec l'experience ATLAS auprès du LHC avec des méthodes d'apprentissage automatique et synchonisation de la description de la géométrie de l'ITk pour la simulation et les études de radiation de la jouvence d'ATLAS pour le HL-LHC
No full textLa mesure du couplage de Yukawa entre le boson de Higgs et le quark top, beaucoup plus fort que celui des autres quarks, permet de tester le Modèle Standard. La production associée d’un boson de Higgs et d’une paire de quarks top (ttH) en permet une mesure directe. Cette thèse documente une recherche d’événements ttH dans le canal H->bb dans les données collectées avec le détecteur ATLAS auprès du LHC durant le Run 2. Les nombreux jets et b-jets dans l’état final nécessitent l’utilisation de techniques avancées. Les grandes incertitudes théoriques sur les bruits de fond tt ont un impact majeur sur la sensibilité.Cette thèse étudie des méthodes d'apprentissage automatique pour améliorer l'analyse ttH(Hbb). Des arbres de décision boostés sont utilisés pour résoudre l’association entre les jets et les partons du signal ttH, puis pour distinguer ttH de tt. La significance observée de la présence de ttH en plus du bruit de fond est 1,4 déviations standard. Différentes techniques d’apprentissage profond ont depuis été explorées pour analyser l’ensemble des données du Run 2 : réseau de neurones récurrent (RNN) pour résoudre simultanément la reconstruction et la classification; réseau profond intégrant des connaissances de physique en plus d'informations de base; RNN multi-catégories pour classer les événements; réseaux antagonistes pour réduire les incertitudes de modélisation de tt.Pour le High-Luminosity LHC; au milieu des années 2020, ATLAS aura un nouveau trajectographe. L’auteure a contribué à la synchronisation des géométries utilisées dans la simulation du détecteur et les études de radiation, étape importante pour valider les estimations de radiation.The Higgs-top coupling (top Yukawa coupling) measurement can further test the standardmodel, being much stronger than the ones for the other quarks. The associated production of aHiggs boson with a top quark pair (ttH) allows to do a direct measurement. With the ATLASdetector at the LHC, this thesis presents a search for ttH in the H->bb decay mode, rarelyproduced compared with the tt backgrounds. Both processes have final states with multiple jetsand b-jets making the analysis heavily relying on advanced techniques. The large tt modelinguncertainties are a driving factor of the sensitivity.This thesis searches to increase the ttH (H->bb) sensitivity by exploring machine learningmethods. Using early Run 2 data, boosted decision trees are exploited to firstly solve the jet-parton assignment in the reconstruction of the ttH signal, and in a second step classify ttH andtt. The observed significance under the background only hypothesis is 1.4 standard deviations.Targeting a contribution to the analysis round using full Run 2 data, deep learningtechniques are explored: recurrent neural networks as binary classifier solving reconstructionand classification in one step, physics-expertise-aware deep neural networks exploiting rawfeatures, RNN-based multi-classifier for event categorization, and adversarial neural networkaimed to decrease the tt modeling uncertainty.Coping with the new LHC phase starting in mid-2020’s, ATLAS will be upgradedto have a new inner tracker. The author contributes to synchronize its geometry descriptionsindependently implemented and used by simulation and radiation studies, which is importantto validate a radiation estimation
Through the thickness heating in the ultrasonic welding of unidirectional thermoplastic composites
No full textResearch and development of thermoplastic composites has been ever increasing owing to the advantages brought by it over conventional materials such as metals and thermoset composites. Higher processing rates, automation, the possibility to recycle, weldability and better mechanical and chemical properties are some of them. Fusion bonding of TPCs that involves application of heat and pressure at the localised bonding area promises faster assembly times and weight reduction and is thus attractive to the aerospace industry. When comparing different welding techniques, ultrasonic welding has the lowest welding times and energy consumption and also overcomes certain challenges that come with the other techniques. The ultrasonic welding process has been a part of the plastic industry for decades, and with time, the research has also shown promising results in welding advanced thermoplastic composites. Heat generation in this mechanical/frictional welding technique occurs due to surface friction and viscoelastic heating caused due to high frequency and low amplitude vibrations. The process creates quality welds in seconds and can be controlled in-situ, ensuring robustness and repeatability. Scaling up the static process to a continuous process enables continuous sealed welds having a more uniform distribution of load and higher load-carrying capability. However, the continuous process brings challenges. The state of the art continuous ultrasonic welding (CUW) equipment at TU Delft has demonstrated quality welds for CF/PPS fabric laminates. However, problems like excessive through the thickness heating (TTH) and deconsolidation of welds need to be understood and overcome.As the industry moves toward welding larger and more complex composites structures such as stringers, frames and skin joints, the CUW process becomes more attractive. The primary thermoplastic structures would involve the use of unidirectional materials. The material that has been proposed for the future structures is the Carbon fiber/ Low Melt - PolyArylEtherKetone composite. LM-PAEK polymer exhibits comparable properties to the other advanced thermoplastic materials like PEEK and PEKK but has a lower processing temperature enabling faster processing. To the author's knowledge, no literature is currently available related to CUW of this material. It was believed that when welding UD / LM-PAEK, the problem of excessive through the thickness heating might be present, leading to fibre and polymer squeeze-out and porosity in the adherends and the need for longer consolidation time. Therefore, this research was focused on investigating the extent of TTH in the ultrasonic welding of this UD material and the solutions to mitigate the effects of TTH on the welds. Static and continuous welding experiments were conducted, and temperature readings were obtained from the adherends and the interface. Along with this, different characterisation techniques such as lap shear tests, fractography and cross-sectional microscopy were used to observe the effects of TTH.CUW showed overall higher TTH. It was observed that changing the fibre architecture from fabric to UD exacerbates the effects of excessive TTH in the adherends. Also, the change in the boundary conditions from that of a static weld to that of a spot or a continuous weld brings in the differences in the viscoelastic bulk heat generation in the top adherend. The cause of this difference is yet to be understood. Changing the process parameters and shape of the sonotrode helped in mitigating the overall TTH in the CUW. The use of a round sonotrode helped in reducing the preheating during welding and the lower welding speeds used, brought the advantage of consolidating the welds for longer times. In conclusion, it was found that changes in the welding and consolidation parameters, and the equipment, can help mitigate the effects of excessive TTH on the adherends. Overcoming the problem of excessive TTH is one of the first steps toward enabling CUW of UD/LM-PAEK composites for future applications.Aerospace Engineerin
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