Automated Fourier space region-recognition filtering for off-axis digital holographic microscopy

Automated label-free quantitative imaging of biological samples can greatly benefit high throughput diseases diagnosis. Digital holographic microscopy (DHM) is a powerful quantitative label-free imaging tool that retrieves structural details of cellular samples non-invasively. In off-axis DHM, a proper spatial filtering window in Fourier space is crucial to the quality of reconstructed phase image. Here we describe a region-recognition approach that combines shape recognition with an iterative thresholding to extracts the optimal shape of frequency components. The region recognition technique offers fully automated adaptive filtering that can operate with a variety of samples and imaging conditions. When imaging through optically scattering biological hydrogel matrix, the technique surpasses previous histogram thresholding techniques without requiring any manual intervention. Finally, we automate the extraction of the statistical difference of optical height between malaria parasite infected and uninfected red blood cells. The method described here pave way to greater autonomy in automated DHM imaging for imaging live cell in thick cell cultures

Concomitant Bacteremia in Adults With Severe Falciparum Malaria.

BackgroundApproximately 6% of children hospitalized with severe falciparum malaria in Africa are also bacteremic. It is therefore recommended that all children with severe malaria should receive broad-spectrum antibiotics in addition to parenteral artesunate. Empirical antibiotics are not recommended currently for adults with severe malaria.MethodsBlood cultures were performed on sequential prospectively studied adult patients with strictly defined severe falciparum malaria admitted to a single referral center in Vietnam between 1991 and 2003.ResultsIn 845 Vietnamese adults with severe falciparum malaria admission blood cultures were positive in 9 (1.07%: 95% confidence interval [CI], .37-1.76%); Staphylococcus aureus in 2, Streptococcus pyogenes in 1, Salmonella Typhi in 3, Non-typhoid Salmonella in 1, Klebsiella pneumoniae in 1, and Haemophilus influenzae type b in 1. Bacteremic patients presented usually with a combination of jaundice, acute renal failure, and high malaria parasitemia. Four bacteremic patients died compared with 108 (12.9%) of 836 nonbacteremic severe malaria patients (risk ratio, 3.44; 95% CI, 1.62-7.29). In patients with >20% parasitemia the prevalence of concomitant bacteremia was 5.2% (4/76; 95% CI, .2-10.3%) compared with 0.65% (5/769; 0.08-1.2%) in patients with ConclusionsIn contrast to children, the prevalence of concomitant bacteremia in adults with severe malaria is low. Administration of empirical antibiotics, in addition to artesunate, is warranted in the small subgroup of patients with very high parasitemias, emphasizing the importance of quantitative blood smear microscopy assessment, but it is not indicated in most adults with severe falciparum malaria

Particle image velocimetry developments for improved near-wall flow measurements

This thesis is a compiled collection of works on the development of Particle Image Velocimetry (PIV) and micro PIV for near-wall flow measurements. PIV has been used to study many large scale industrial and biological flows, and micro PIV is increasingly utilised in micro-biological and micro-fluidic flow measurements. Both of the methods however suffer significant errors in the measurements of near wall flows due to the effects of the wall boundary and high velocity gradients. In addition, micro PIV suffers significant errors due to volume illumination and the resultant imaging of out-of-focus particles. Many important phenomena such as near-wall turbulence, near-wall transportation of particles or blood cells occur in near-wall regions, and significant improvement of PIV and micro PIV is required. This thesis is devoted to providing solutions to this demand by proposing three new PIV and micro PIV measurement techniques: image overlapping, volumetric-correlation PIV and interfacial PIV. Although these techniques can be applied to general applications, they have been optimised for biological applications. Image overlapping, when applied to micro PIV data, improves the measurement accuracy by effectively reducing the effect of out-of-focus particles. In micro PIV the imaging of out-of-focus particles by volume illumination causes significant measurement bias over the measurement depth. Image overlapping improves measurement accuracy significantly more than currently available techniques, while requiring fewer computational resources. In contrast to improving micro PIV accuracy by reducing the out-of-focus effect, volumetric-correlation PIV (VPIV) utilises this effect to provide 3-dimensional, 2-component (3D2C) velocity fields. VPIV is further extended to uniquely measure particle concentration. The concentration measurements improve the velocity measurement accuracy and provide additional information to study near-wall particle transport phenomena. VPIV simplifies 3D velocity measurements while requiring cheaper hardware. Challenging PIV and micro PIV measurements of flows near curved walls are further resolved by interfacial PIV. In this technique the fluid regions near curved walls are straightened by conformal transformation and a wall-normal velocity profile, with one-pixel resolution, is obtained utilising a novel line-correlation function and curve fitting. Interfacial PIV substantially simplifies the manual image rotation normally required in traditional PIV techniques, while increasing both the resolution of the near-wall velocity profiles and the accuracy of the wall-shear velocity gradient

Particle image velocimetry developments for improved near-wall flow measurements

This thesis is a compiled collection of works on the development of Particle Image Velocimetry (PIV) and micro PIV for near-wall flow measurements. PIV has been used to study many large scale industrial and biological flows, and micro PIV is increasingly utilised in micro-biological and micro-fluidic flow measurements. Both of the methods however suffer significant errors in the measurements of near wall flows due to the effects of the wall boundary and high velocity gradients. In addition, micro PIV suffers significant errors due to volume illumination and the resultant imaging of out-of-focus particles. Many important phenomena such as near-wall turbulence, near-wall transportation of particles or blood cells occur in near-wall regions, and significant improvement of PIV and micro PIV is required. This thesis is devoted to providing solutions to this demand by proposing three new PIV and micro PIV measurement techniques: image overlapping, volumetric-correlation PIV and interfacial PIV. Although these techniques can be applied to general applications, they have been optimised for biological applications. Image overlapping, when applied to micro PIV data, improves the measurement accuracy by effectively reducing the effect of out-of-focus particles. In micro PIV the imaging of out-of-focus particles by volume illumination causes significant measurement bias over the measurement depth. Image overlapping improves measurement accuracy significantly more than currently available techniques, while requiring fewer computational resources. In contrast to improving micro PIV accuracy by reducing the out-of-focus effect, volumetric-correlation PIV (VPIV) utilises this effect to provide 3-dimensional, 2-component (3D2C) velocity fields. VPIV is further extended to uniquely measure particle concentration. The concentration measurements improve the velocity measurement accuracy and provide additional information to study near-wall particle transport phenomena. VPIV simplifies 3D velocity measurements while requiring cheaper hardware. Challenging PIV and micro PIV measurements of flows near curved walls are further resolved by interfacial PIV. In this technique the fluid regions near curved walls are straightened by conformal transformation and a wall-normal velocity profile, with one-pixel resolution, is obtained utilising a novel line-correlation function and curve fitting. Interfacial PIV substantially simplifies the manual image rotation normally required in traditional PIV techniques, while increasing both the resolution of the near-wall velocity profiles and the accuracy of the wall-shear velocity gradient

The fear of public speaking in Vietnamese pedagogy freshmen

Fear of public speaking, also known as Glossophobia which is defined as a form of social phobia leading to severely discourage speaking publicly owing to the dread of being ashamed or losing the respect of other people. The recent study used the Personal Report of Public Speaking Anxiety scale including 34 items to survey 374 pedagogy freshmen. The sample consisted of 374 students of which 144 students studying Social Science (38.5%), 140 students studying Natural Science (37.4%), and 90 students studying Educational Science (24.1%) of which were 86 males (23%) and 288 females (77%). The main finding of this study was that a large number of pedagogy freshmen suffered fear of public speaking. Besides, the result found that the difference between the three groups of majors in the levels of glossophobia just very slightly missed the significance level. Educational Science students suffered most public speaking anxiety in three groups of majors. To become professional educators in the future, pedagogy freshmen have to cultivate and self-improve speaking publicly skill which is one of the most essential and crucial soft skills. Additionally, the presentation skill is one of the compulsory academic activities and criteria for evaluation of the university of education. These findings contribute to developing courses aiming to reduce student’s public speaking anxiety and improve their presentation skill. Besides, educators could create an education curriculum that is most suitable for freshmen and not causes much pressure leading to their anxiety

Effective photocatalytic activity of mixed Ni/Fe-base metal-organic framework under a compact fluorescent daylight lamp

Mixed Ni/Fe-base metal-organic framework (Ni/Fe-MOF) with different molar ratios of Ni 2+ /Fe 3+ have been successfully produced using an appropriate solvothermal router. Physicochemical properties of all samples were characterized using X-ray diffraction (XRD), Raman, field emission scanning electron microscopes (FE-SEM), fourier-transform infrared spectroscopy (FT-IR), N 2 adsorption-desorption analysis, X-ray photoelectron spectroscopy (XPS), ultraviolet-visible diffuse reflectance spectra (UV-Vis DRS), and photoluminescence spectra (PL). The photocatalytic degradation performances of the photocatalysts were evaluated in the decomposition of rhodamine B (RhB) under a compact fluorescent daylight lamp. From XRD, IR, XPS, and Raman results, with the presence of mixed ion Fe 3+ and Ni 2+ , MIL-88B (MIL standing for Materials of Institut Lavoisier) crystals based on the mixed metal Fe 2 NiO cluster were formed, while MIL-53(Fe) was formed with the presence of single ion Fe 3+ . From UV-Vis DRS results, Ni/Fe-MOF samples exhibited the absorption spectrum up to the visible region, and then they showed the high photocatalytic activity under visible light irradiation. A Ni/Fe-MOF sample with a Ni 2+ /Fe 3+ molar ratio of 0.3 showed the highest photocatalytic degradation capacity of RhB, superior to that of the MIL-53(Fe) sample. The obtained result could be explained as a consequence of the large surface area with large pore volumes and pore size by the Ni 2+ incorporating into the MOF’s structure. In addition, a mixed metal Fe/Ni-based framework consisted of mixed-metal cluster Fe 2 NiO with an electron transfer effect and may enhance the photocatalytic performance

Viral aetiology of central nervous system infections in adults admitted to a tertiary referral hospital in southern Vietnam over 12 years

Central nervous system (CNS) infections are important diseases in both children and adults worldwide. The spectrum of infections is broad, encompassing bacterial/aseptic meningitis and encephalitis. Viruses are regarded as the most common causes of encephalitis and aseptic meningitis. Better understanding of the viral causes of the diseases is of public health importance, in order to better inform immunization policy, and may influence clinical management. Study was conducted at the Hospital for Tropical Diseases in Ho Chi Minh City, a primary, secondary, and tertiary referral hospital for all southern provinces of Vietnam. Between December 1996 and May 2008, patients with CNS infections of presumed viral origin were enrolled. Laboratory diagnostics consisted of molecular and serological tests targeted at 14 meningitis/encephalitis-associated viruses. Of 291 enrolled patients, fatal outcome and neurological sequelae were recorded in 10% (28/291) and 27% (78/291), respectively. Mortality was especially high (9/19, 47%) amongst those with confirmed herpes simplex encephalitis which is attributed to the limited availability of intravenous acyclovir/valacyclovir. Japanese encephalitis virus, dengue virus, herpes simplex virus, and enteroviruses were the most common viruses detected, responsible for 36 (12%), 19 (6.5%), 19 (6.5%) and 8 (2.7%) respectively, followed by rubella virus (6, 2%), varicella zoster virus (5, 1.7%), mumps virus (2, 0.7%), cytomegalovirus (1, 0.3%), and rabies virus (1, 0.3%). Viral infections of the CNS in adults in Vietnam are associated with high morbidity and mortality. Despite extensive laboratory testing, 68% of the patients remain undiagnosed. Together with our previous reports, the data confirm that Japanese encephalitis virus, dengue virus, herpes simplex virus, and enteroviruses are the leading identified causes of CNS viral infections in Vietnam, suggest that the majority of morbidity/mortality amongst patients with a confirmed/probable diagnosis is preventable by adequate vaccination/treatment, and are therefore of public health significanc

Predictive Factors of Mortality in Patients with Severe COVID-19 Treated in the Intensive Care Unit: A Single-Center Study in Vietnam

Abstract Introduction The fourth outbreak of COVID-19 with the delta variant in Vietnam was very fierce due to the limited availability of vaccines and the lack of healthcare resources. During that period, the high mortality of patients with severe and critical COVID-19 caused many concerns for the health system, especially the intensive care units. This study aimed to analyze the predictive factors of death and survival in patients with severe and critical COVID-19. Methods We conducted a cross-sectional and descriptive study on 151 patients with severe and critical COVID-19 hospitalized in the Intensive Care Unit of Binh Duong General Hospital. Results Common clinical symptoms of severe and critical COVID-19 included shortness of breath (97.4%), fatigue (89.4%), cough (76.8%), chest pain (47.7%), loss of smell (48.3%), loss of taste (39.1%), and headache (21.2%). The abnormal biochemical features were leukopenia (2.1%), anemia, thrombocytopenia (18%), hypoxia with low PaO2 (34.6%), hypocapnia with reduced PaCO2 (29.6%), and blood acidosis (18.4%). Common complications during hospitalization were septic shock (15.2%), cardiogenic shock (5.3%), and embolism (2.6%). The predictive factors of death were being female, age > 65 years, cardiovascular comorbidity, thrombocytopenia (< 137.109/l), and hypoxia at inclusion or after the first week or blood acidosis (pH < 7.28). The use of a high dose of corticosteroids reduced the mortality during the first 3 weeks of hospitalization but significantly increased risk of death after 3 and 4 weeks. Conclusions Common clinical symptoms, laboratory features, and death-related complications of critical and severe COVID-19 patients were found in Vietnamese patients during the fourth wave of the COVID-19 pandemic. The results of this study provide new insight into the predictive factors of mortality for patients with severe and critical COVID-19