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Technology for providing clean drinking water to remote areas of low-resource nations remains a significant challenge for human life The study aimed to develop a simple technology for rural households that might be adopted to utilize the bactericidal properties of metals. Three thick metal sheets made of copper, zinc, and brass (an alloy of copper and zinc) were used in this study work. These metallic sheets were placed in three plastic (polythene) containers with base areas 11cm x 7cm each so that the metallic sheets covered the entire base areas of the respective containers. Fifty ml, one hundred ml, and four hundred ml of contaminated water from a public pond were added to each container, covered with lids, and shaken/left undisturbed at room temperature. The microbial analysis of Total Aerobic Bacteria (TAB), Total Coliform Bacteria (TCC), and E. coli was done every 24 hours up to twenty-eight days of storage at room temperature. E. coli is considered an indicator of diarrhoeal pathogens. The initial bacterial counts were TAB: 4.22 log CFU/ml, TCC: 3.15 log CFU/ml, and E.coli: 3.13 log CFU/ml, respectively. TAB count did not reduce significantly for any of the metals used in this study. Total coliform counts decreased to almost half the original for all three metals in the first 24 hours but remained almost the same afterward. However, E.coli was inactivated entirely after treatment with copper within 24h and remained constant afterward. On the other hand, brass and zinc reduced E. coli by almost half in the first 24 hours but remained almost constant throughout the rest of the measured period. The findings mentioned above, a simple copper sheet might help inactivate diarrheal bacteria and provide safe drinking water within 24 hours. As a result, this may lead to the development of an easy technique to provide clean drinking water in remote areas of low-resource nations like Bangladesh. It is crucial to determine whether the level of copper in the water is within the safe range, as regular usage of higher doses might result in copper poisoning. A future study will attempt to optimize the relationship between the water volume to the copper sheet’s exposed surface area and the treatment time. Bangladesh J Microbiol, Volume 39, Number 2, December 2022, pp 54-59

Bio-Electrical impedance is of special interest in the detection and diagnosis of lung problems, particularly in the low and medium income countries. An age old simple technique employing four electrodes is known as ‘Tetra Polar Impedance Measurement (TPIM)’ but it cannot localize a particular zone of interest region. A new technique named as ‘Focused Impedance Method (FIM)’ was innovated by a Dhaka University group which gives high sensitivity in a localized zone of interest. Previously FIM was used from one side of the thorax which gave a rather limited information from the lungs, from shallow depths only. In order to get information from deeper regions of the lungs a new configuration of electrodes for FIM was proposed by the same group at Dhaka University which placed two electrodes at the front and two electrodes at the back of the thorax in a horizontal plane. It is expected that the degree of depth sensitivity would depend on electrode separation on both the sides. The electrode width may also have an effect. In order to study these quantitatively, COMSOL Multiphysics software was used to simulate the measurements in a rounded rectangular volume to represent a typical thorax, which was filled with isotonic saline. Electrode separations of 5cm, 10cm, 15cm and 20cm were studied while electrode widths studied were 0.15cm, 1cm and 3cm. The work supported the proposed new configuration of electrodes for FIM in that this method gives enhanced sensitivity throughout the depths of a lung and that for a thorax with a cross section of 33cm26cm, an electrode separation between 10cm and 15cm would give optimum results. For electrode width, the ones studied did not give any significant difference, however, the smallest (0.15cm) one appeared to give slightly better results. Bangladesh Journal of Medical Physics Vol.15 No.1 2022 P 43-54

Ephemeral gully erosion is a primary mode of soil erosion that is highly visible, affecting soil productivity and restricting land use. Watershed is the basic unit of soil erosion control; existing research has focused on several typical ephemeral gullies or slopes, which do not fully display changes in ephemeral gullies at a watershed scale. This study analyzed the spatial-temporal evolution and development rate of ephemeral gully erosion at the watershed scale on the Loess Plateau from 2009 to 2021 using remote sensing images (0.5 m resolution), unmanned aerial vehicles (UAV), and field investigations. The results revealed that: (1) most ephemeral gullies occurred in southwestern parts of the watershed, with many hills and large slope gradients; (2) average growth rates of each ephemeral gully frequency, length, density, dissection degree, and width were 2.87 km y , 1.66 m y , 0.12 km km y , 0.0125% y , and 0.04 m y , respectively; (3) ephemeral gully erosion volume ( V) and length ( L) had a good power function relationship: V = 0 . 0842 L 1 . 1932 ( R 2 = 0 . 80 ) . The root mean square error (RMSE) and coefficient of determination (R ) between the measured and predicted ephemeral gully volumes suggest that the V–L relationship has a good predictive ability for ephemeral gully volume. Thus, the V–L model was used to evaluate the development rate of ephemeral gully erosion volume in small watersheds from 2009 to 2021, revealing an average value of 743.20 m y . This study proposed a feasible model for assessing ephemeral gully volume and volume changes at a watershed scale using high-resolution remote sensing images, providing a reference for understanding the development of ephemeral gully erosion in small watersheds over time.

Cobalt metal is considered as an essential trace element for the animals. Present investigation was undertaken in the peri-urban area to analyze the cobalt availability in animal food chain by using different indices. Cow, buffalo and sheep samples along with forage and soil samples were collected from the three different sites of District Jhang and analyzed through atomic absorption spectrophotometer. Cobalt values differed in soil samples as 0.315-0.535 mg/kg, forages as 0.127-0.333 mg/kg and animal samples as 0.364-0.504 mg/kg. Analyzed cobalt concentration in soil, forage and animal samples was found to be deficient in concentration with respect to standard limits. Soil showed the minimum cobalt level in Z. mays while maximum concentration was examined in the forage C. decidua samples. All indices examined in this study has values lesser than 1, representing the safer limits of the cobalt concentration in these samples. Enrichment factor (0.071-0.161 mg/kg) showed the highly deficient amount of cobalt enrichment in this area. Bio-concentration factor (0.392-0.883) and pollution load index (0.035-0.059 mg/kg) values were also lesser than 1 explains that plant and soil samples are not contaminated with cobalt metal. The daily intake and health risk index ranged from 0.00019-0.00064 mg/kg/day and 0.0044-0.0150 mg/kg/day respectively. Among the animals, cobalt availability was maximum (0.0150 mg/kg/day) in the buffaloes that grazed on the C. decidua fodder. Results of this study concluded that cobalt containing fertilizers must be applied on the soil and forages. Animal feed derived from the cobalt containing supplements are supplied to the animals, to fulfill the nutritional requirements of livestock. Resumo O metal cobalto é considerado um oligoelemento essencial para os animais. A presente investigação foi realizada na área periurbana para analisar a disponibilidade de cobalto na cadeia alimentar animal usando diferentes índices. Amostras de vacas, búfalos e ovelhas, juntamente com amostras de forragem e solo foram coletadas em três locais diferentes do Distrito Jhang e analisadas por meio de espectrofotômetro de absorção atômica. Os valores de cobalto diferiram em amostras de solo como 0,315-0,535mg/kg, forragens como 0,127-0,333 mg/kg e amostras de animais como 0,364-0,504 mg/kg. A concentração de cobalto analisada no solo, forragem e amostras de animais foi considerada deficiente em relação aos limites padrão. O solo apresentou o teor mínimo de cobalto em Z. mays enquanto a concentração máxima foi examinada nas amostras de forragem C. decidua. Todos os índices examinados neste estudo possuem valores menores que 1, representando os limites mais seguros da concentração de cobalto nestas amostras. O fator de enriquecimento (0,071-0,161 mg/kg) mostrou a quantidade altamente deficiente de enriquecimento de cobalto nesta área. Os valores do fator de bioconcentração (0,392-0,883) e do índice de carga de poluição (0,035-0,059 mg/kg) também foram menores que 1, o que explica que as amostras de plantas e solo não estão contaminadas com cobalto metálico. A ingestão diária e o índice de risco à saúde variaram de 0,00019-0,00064 mg/kg/dia e 0,0044-0,0150 mg/kg/dia, respectivamente. Entre os animais, a disponibilidade de cobalto foi máxima (0,0150 mg/kg/dia) nos búfalos que pastaram na forragem de C. decidua. Os resultados deste estudo concluíram que fertilizantes contendo cobalto devem ser aplicados no solo e nas forragens. A ração animal derivada dos suplementos contendo cobalto é fornecida aos animais, para atender às necessidades nutricionais do gado.

Probing deep regions of the lung using electrical impedance is very important considering the need for a low cost and simple technique, particularly for the low and medium income countries. Because of complexity and cost, Electrical Impedance Tomography is not suitable for this envisaged application. The simple Tetrapolar Impedance Measurement (TPIM) technique employing four electrodes is the age old technique for bioelectrical measurements. However, it has its limitations in respect of organ localisation and depth sensitivity using skin surface electrodes. Recently, a new 6-electrode TPIM with two current electrodes but two pairs of appropriately connected potential electrodes positioned on the front and back of the thorax, proposed by one of the authors, came with a promise. However, this work gave a qualitative proposal based on concepts of physics and lacked a quantitative evaluation. In order to evaluate the method quantitatively, the present work employed finite element method based COMSOL Multiphysics software and carried out simulation studies using this new 6-electrode TPIM and compared the results with those from 4-electrode TPIM, with electrodes applied either on the front or at the back of the thorax for the latter. Initially, it carried out a sensitivity distribution study using a simple rectangular volume conductor which showed that the 6-electrode TPIM gives better depth sensitivity throughout the lung region. Next it used a near life like thorax model developed by another of the authors earlier. Using this model, extensive studies were carried out to quantify the overall sensitivity over a target lung region, the contribution of the target lung to the total measured impedance, and several other parameters. Through these studies, the 6-electrode TPIM was established on a stronger footing for probing deep regions of the lungs.

The astounding developments in healthcare technology is not available to about 84% of the global population in the low-medium income countries (LMIC). Good meaning medical equipment donation programmes from the high income countries (HIC) have made very little impact, most devices failing to give the desired service and increasing e-waste. The author, with his four decade-long experience feels that people in the LMICs with higher education in science and technology should be motivated and trained in the design and manufacture of medical devices, and they should also take the responsibility for commercial manufacture and distribution of the developed products. With this realisation early in life, he initiated similar efforts in his home country Bangladesh about four decades back against many challenges and obstacles. This produced some success stories and this paper lists some of the devices developed and distributed by groups under his leadership. The author argues that the existing industries in the LMICs are based on fully foreign technology, and do not have the capability or preparedness to take up commercial manufacture of indigenously developed technology based products. He has come up with the design of a ‘Micro-eco-system’ for the LMICs which involve the leadership of a single technology innovator or a single group of innovators to organise R&D and commercial manufacture, both. An LMIC may have hundreds or thousands of the above ‘Micro-eco-system’ to create an overall eco-system, which may be the solution eventually leading to a more equitable world, with each and every person of the globe having access to developments in science and technology in healthcare. Bangladesh Journal of Medical Physics Vol.14 No.1 2021 P 1-15

Focused Impedance Method (FIM) is a new and simple technique of electrical bio-impedance that provides an opportunity for localized measurement down to reasonable depths of the body surface using skin surface electrodes. Conceived by one of the authors (KSR) and developed in Bangladesh by a group led by him, FIM has potential applications in physiological study and in the detection or diagnosis of diseases and disorders. Being a simple technique, it is particularly suitable for low and medium income countries (LMIC). To obtain long term benefit from any technology it is necessary that the technology is understood and developed indigenously, particularly under the limitation of a resource limited country. Indigenous development also allows for further improvisation, innovation, and application in future. This paper presents the indigenous design and development of the electronic instrumentation necessary for the implementation of six electrode version of Focused Impedance Method (FIM-6) in Nepal. The work involved basic characterization of the necessary circuit blocks developed through experimental validation. In particular, the design of isolating ferrite transformers required for the instrumentation posed a challenge which was solved limiting the range of the instrumentation to range variations encountered in practice on the human body, for which initial experiments were carried out on a live human subject. This led to a simplified design. The values obtained using the developed circuitry appears to give reasonable accuracy and would be useful for further implementation of the instrumentation using PCBs. However, further work can also be taken to improve the design of the current source used and of the transformers. Thus this work satisfies the initial requirement of attempting indigenous development of the FIM technique in an LMIC like Nepal. Bangladesh Journal of Medical Physics Vol.14 No.1 2021 P 1-15

Inspired by Mantis shrimp, this work aims to suggest a bottom-up approach for the fabrication of nanonetwork hydroxyapatite (HAp) thin film using self-assembled polystyrene

Extreme meteorological events occur frequently, and changes in the spatial pattern of land use have greatly affected the soil erosion process in the hilly and gully region of the Loess Plateau. As a typical governance watershed in the hilly and gully area of the Loess Plateau, the Jiuyuangou watershed has experienced significant changes in land use and land cover (LULCC) in the past ten years due to the conversion of farmland to forests, economic construction, and abandonment of cultivated land. However, the evolution process of soil erosion under LULCC in the watershed is unclear. This study uses satellite images to extract information on LULCC in the watershed and the Chinese soil loss equation (CSLE) model to evaluate the temporal and spatial evolution of soil erosion in the watershed from 2010 to 2020. The main results showed that: (1) The continuous vegetation restoration project in the watershed reduced soil erosion from 2010 to 2015; however, the frequency of extreme rainfall events after 2015 reduced its impact. The annual average soil erosion modulus decreased from 10.85 t ha yr in 2010 to 8.03 t ha yr in 2015, but then increased to 10.57 t ha yr in 2020; (2) The main LULC type in the Jiuyuangou watershed is grassland, accounting for 62.23% of the total area of the watershed, followed by forest land (28.41%), cropland (6.77%), building (2.49%), and water (0.09%). The multi-year average soil erosion modulus for land use type is cropland > grassland > building > forest land; (3) Significant spatial correlations between soil erosion change and LULCC for common ‘no change’ and common ‘gain’ occurred in the settlements, roads, valleys, and areas near the human influences with good soil and water conservation, but not other regions due to the influence of climatic factors (heavy rain events). This study provides a scientific reference for planning and managing water and soil conservation and ecological environment construction in the basin.

Gully erosion is one of the main modes of slope erosion on the Loess Plateau, which plays a connecting role in the slope gully erosion system. The Loess Plateau has wide and densely distributed gullies. The study selected a typical small watershed in the hilly and gully region of the Loess Plateau to measure the morphological characteristics and spatial-temporal distribution of gullies. A deep learning image semantic segmentation model was used to identify and extract the morphological features of gullies at the watershed scale from 2009 to 2021 based on remote sensing images (0.5 m resolution) and then analyze their temporal and spatial distribution characteristics. The results revealed that: (1) most gullies occurred in the hilly southern parts of the watershed, which has complex landforms and large slope gradients; (2) gully number increased from 1,159 in 2009 to 2,312 in 2021 (average 97 per year), with a frequency development rate of 2.87 km y ; (3) gully length generally ranged from 25–40 m, with an average growth rate is 1.66 m y and density development rate of 0.12 km km y ; (4) gully width ranged from 0.5–1.5 m, with an average growth rate of 0.04 m y . (5) the total gully area increased from 0.0566 km² in 2009 to 0.1072 km² in 2021, with a development rate of 4,213.39 m² y and dissection degree development rate of 0.0125% y . This study provides a theoretical and scientific basis for gully erosion control and eco-environmental protection at the watershed scale on the Loess Plateau.

Herein, this work aims to fabricate well-ordered nanonetwork epoxy resin modified with poly(butyl acrylate)-b-poly(methyl methacrylate) (PBA-b-PMMA) block copolymer (BCP) for enhanced energy dissipation using a self-assembled diblock copolymer of polystyrene-b-poly(dimethylsiloxane) (PS-b-PDMS) with gyroid and diamond structures as templates. A systematic study of mechanical properties using nanoindentation of epoxy resin with gyroid- and diamond-structures after modification revealed significant enhancement in energy dissipation, with the values of 0.36 ± 0.02 nJ (gyroid) and 0.43 ± 0.03 nJ (diamond), respectively, when compared to intrinsic epoxy resin (approximately 0.02 ± 0.002 nJ) with brittle characteristics. This enhanced property is attributed to the synergic effect of the deliberate structure with well-ordered nanonetwork texture and the toughening of BCP-based modifiers at the molecular level. In addition to the deliberate structural effect from the nanonetwork texture, the BCP modifier composed of epoxy-philic hard segment and epoxy-phobic soft segment led to dispersed soft-segment domains in the nanonetwork-structured epoxy matrix with superior interfacial strength for the enhancement of applied energy dissipation.

Tetrapolar Impedance Method (TPIM) and Focused Impedance Method (FIM) are two simple modalities of electrical bio-impedance measurement that could be employed to give useful physiological and diagnostic information of the human body. FIM is based on TPIM but uses a combination of two sets of TPIM, producing a focusing effect, which is useful to localize specific target organs. Most non-invasive electrical bio-impedance measurements based on TPIM and FIM use electrodes on one side of the body, outside the skin surface, which gives a shallow depth sensitivity. The sensitivity decreases with depth so that deep organs like lungs, heart, liver, stomach and bladder are not fully assessed through such measurements. Based on a long experience of studying electrical impedance methods, several qualitative ideas are presented in this article for probing deep organs using a few modified TPIM and FIM configurations. The suggestions are based on visualisations of both equipotentials and a popular sensitivity equation for transfer impedance, but not based on any quantitative analysis. Simulation and phantom studies based on these ideas may produce some practically useful electrode configurations for real life bio-impedance measurements. Bangladesh Journal of Medical Physics Vol.11 No.1 2018 P 1-15

Mid-upper arm circumference (MUAC) is an important indicator of the nutritional index, particularly of children in low resource countries of the world. It is a significant anthropometric tool with simple cut-off values which is easy to implement in large scale screening measurements. A conventional MUAC device is essentially an insertion strap and has many merits over other anthropometric measurements techniques, but a lack of reproducibility in measurements is its leading problem since the measurement depends on how strongly a person pulls the strap around an arm of the subject. The aim of the present study is to minimize this reproducibility problem. For this the existing MUAC device has been modified using a short length of an elastic band to provide a constant tension while measuring, making it a Constant Tension MUAC device. Using both the MUAC devices (conventional and CT-MUAC), data were collected from seven subjects by 70 observers (10 observers measuring one subject). Statistical analyses showed that the CT-MUAC device gives a significant improvement with less variability over the conventional device. Thus, the new CT-MUAC device has the potential for improved detection of malnutrition throughout the world. Bangladesh Journal of Medical Physics Vol.11 No.1 2018 P 26-37

Herein, we aim to develop a facile method for the fabrication of mechanical metamaterials from templated polymerization of thermosets including phenolic and epoxy resins using self-assembled block copolymer, polystyrene-polydimethylsiloxane with tripod network (gyroid), and tetrapod network (diamond) structures, as templates. Nanoindentation studies on the nanonetwork thermosets fabricated reveal enhanced energy dissipation from intrinsic brittle thermosets due to the deliberate structuring; the calculated energy dissipation for gyroid phenolic resins is 0.23 nJ whereas the one with diamond structure gives a value of 0.33 nJ. Consistently, the gyroid-structured epoxy gives a high energy dissipation value of 0.57 nJ, and the one with diamond structure could reach 0.78 nJ. These enhanced properties are attributed to the isotropic periodicity of the nanonetwork texture with plastic deformation, and the higher number of struts in the tetrapod diamond network in contrast to tripod gyroid, as confirmed by the finite element analysis.

Pseudomyxoma peritonei is a rare abdominal tumor with a reported incidence of approximately I per million per year. It is invariably fatal as the space within the abdomen is eventually replaced by mucinous tumor. We report one case of Pseudomyxoma peritonei.

Both PU and PC increased maize yield, water use efficiency (WUE), and partial factor productivity from applied N (PFPN), relative to CK. PC increased maize yield more than PU, and had higher soil organic carbon (SOC) content than PU, which was mainly due to the decline in SOC stocks in the 250–2000, 53–250, and

Mixing a small amount of magnetic beads and regents with large volume samples evenly in microcavities of a microfluidic chip is always the key step for the application of microfluidic technology in the field of magnetophoresis analysis. This article proposes a microfluidic chip for DNA extraction by magnetophoresis, which relies on bubble rising to generate turbulence and microvortices of various sizes to mix magnetic beads with samples uniformly. The construction and working principle of the microfluidic chip are introduced. CFD simulations are conducted when magnetic beads and samples are irritated by the generation of gas bubbles with the variation of supply pressures. The whole mixing process in the microfluidic chip is observed through a high-speed camera and a microfluidic system when the gas bubbles are generated continuously. The influence of supply pressure on the mixing characteristics of the microfluidic chip is investigated and discussed with both simulation and experiments. Compared with magnetic mixing, bubble mixing can avoid the magnetic beads gather phenomenon caused by magnetic forces and provide a rapid and high efficient solution to realize mixing small amount of regents in large volume samples in a certain order without complex moving structures and operations in a chip. Two applications of mixing with the proposed microfluidic chip are also carried out and discussed.

Background The medical community’s understanding of the novel coronavirus disease (COVID-19) was limited initially, and many laboratory investigations were performed to observe effects of the virus on the body, its complications, and outcomes. We observed that some laboratory investigations provided redundant information regarding outcomes, and, therefore, were not necessary. Therefore, the extent of laboratory investigations may need to be pared down to not only avoid issues related to repeated blood sampling but also to minimize the financial burdens in poor socioeconomic countries. Objective This study aimed to observe trends of clinical and laboratory values in COVID-19 patients and their relationship to outcomes, including disease severity, length of hospital stay, and mortality. Methods We conducted an observational cohort study of COVID-19 patients treated as inpatients at the Shifa International Hospital (SIH) in Islamabad in April 2020. Patients were included if they were nonsurgical, adult inpatients of SIH diagnosed with COVID-19 via positive polymerase chain reaction test. We monitored study participants' clinical and laboratory values (including hypoxia) on admission and throughout the study period. We used IBM SPSS Statistics for Windows, Version 23.0 (IBM Corp., Armonk, NY, USA) for data entry and analysis. Descriptive statistics were calculated for qualitative and quantitative data. We determined the effect of all variables on outcomes through chi-squared or Fisher's exact test, and p-values

Basin type solar stills were made with two types of top cover, transparent PVC sheet and another with glass sheet. A soaked black towel was at the base which was heated through green-house effect and contributed to the water for distillation. Productivity of these two basin type solar stills were studied at different tilt angles of the top transparent cover with ground surface (13o, 23o and 35o). The average amount of distilled water produced increased with the tilt angles for both types of cover materials, that for glass being much higher than that for PVC cover.Bangladesh Journal of Medical Physics Vol.10 No.1 2017 40-46

In biomedical instrumentation, computer based data acquisition system is required for recording of physiological parameters and bioelectric signals, which allows signal processing, display, analysis and storage in digital media. However, Most of the commercially available PC based Data Acquisition systems are of very high cost and requires specific commercial software, again at a very high cost. Moreover, if the data is not stored in raw binary or known format, it is not possible for the user to use the data in other system or software of their own choice. Therefore, a low cost, simple and open source PC based data acquisition system for biomedical application would be very useful for biomedical instrument developers and researchers in the low resource countries. In this work, we present such development of data acquisition system. The developed system utilizes an 8-bit ordinary low cost microcontroller and some electronic circuit component to develop the data acquisition system and implementation of USB 1.1 (Universal Serial Bus) interface to PC. The onboard 10-bit ADC of the microcontroller was used for analog data sampling. Two sampling and data transfer mode is implemented, (i) Continuous mode with low sampling rate (800 sample/sec) and practically real time plotting and (ii) Batch mode, with high sampling rate (76.9 k sample/sec) but with batch type plotting. To evaluate the system, PC side GUI (Graphical User Interface) software was also developed. The GUI of system shows that a test sinusoidal signal is reproduced very nicely without any amplitude and phase distortion within the frequency band of 1 to 10 KHz. The system is suitable for low frequency bioelectric signals like ECG, EEG etc. and as well as high frequency signal like EMG, NCV etc. The system is low cost, miniature, simple, and efficient and being used in several indigenously developed medical devices like ECG, EMG, NCV and FIM [Rabbani et al, 1999] at the authors’ department with excellent satisfactory results.Bangladesh Journal of Medical Physics Vol.10 No.1 2017 1-11

Distribution of F-Latency (DFL) is a new neurological parameter conceived by the Biomedical Physics group of Dhaka University. Previous experimental studies have indicated that DFL, obtained from median nerve, varies with postures of the subject, particularly with the bending of the head. It agreed with the contention that bending of head might produce compression or stretching of nerve fibers as they come out of the vertebra, and that DFL is a sensitive parameter that gets affected by even such temporary changes. The present work was taken up with two objectives, i) to improve upon the earlier work by taking measurements with a few specific angles of head bending, particularly in the left and right directions, and ii) to provide a verification of earlier results. For bending of head to left and right sides, we chose 300 and 450 respectively. For forward and backward directions the angles were not measured and the subjects were asked to bend as much as they could without going beyond a comfort level. The study was carried out on 6 student volunteers aged between 24 and 26. The DFLs obtained with different postures of the head were analyzed to look for systematic trends in the changes, if any. Changes in several parameters like peak, mean, standard deviation, skewness and half-width in the rising and falling edges (down to 50 % height of the peak) were studied for different postures of head and neck which showed consistent changes.Bangladesh Journal of Medical Physics Vol.9 No.1 2016 1-10

Spirometry, or measurement of respiration conventionally involves measurement of the time variation of volume or flow of air breathed in or out through the mouth using an air-flow sensor. Electrical impedance of thorax changes during breathing and conceptually this modality should be applicable in spirometry, but no attempts have been made so far. This paper describes the development of an electrical impedance based spirometer placing electrodes on four limbs so that the whole lung volume may contribute to the measurement. An impedance based measurement system (IBS) consisting of a constant current drive at 11 kHz and necessary voltage measurement circuitry was designed and developed for this purpose. A portable oscilloscope (PicoScope 2208A) was used for acquisition of the measured voltage signal to a PC and an algorithm in Matlab software was used to demodulate the time varying impedance from a carrier signal. The variation of impedance with time during forced expiration as measured by the implemented impedance measurement system was compared with that obtained using a standard bellows type commercial spirometer (Vitalograph) on eight volunteers, between 22 and 32 years of age. The subjects included smokers, non-smokers, and asthma patients. Repeatability of the measurements were satisfactory. The correlation coefficient between the spirogram obtained using the IBS and that obtained using standard spirometer varied from 0.81 to 0.99 indicating preliminary success of the proposed technique. However, a possible source of error is the bending of the body during forced expiration which, if prevented, may give a better outcome.Bangladesh Journal of Medical Physics Vol.9 No.1 2016 17-27