Numerical Modeling and Experimental Investigation of Improved Mixing From Both Coriolis Effect and Go¨rtler Vortices in Rotating Zigzag Microchannel

2011 ◽  
Author(s):  
Yong Ren ◽  
Wallace Woon-Fong Leung
Keyword(s):  
Pressure Head ◽  
Stationary Condition ◽  
Coriolis Effect ◽  
Straight Channel ◽  
Centrifugal Effect ◽  
Cross Sectional ◽  
Mixing Performance ◽  
Study Results ◽  
The Cost ◽  
Zigzag Shape

The flow pattern and mixing performance in different geometries of microchannels are investigated. A study for the zigzag shape channel under both stationary and rotation condition was investigated. The results are compared to the straight channel. Both numerical model via CFD and experiments are agreeing with each other. It is found when the channel is under rotation, the mixing performance is better than the stationary condition due to rotation induced Coriolis effect. As the rotation speed increases from 300rpm to 900rpm, an improved mixing performance can be further obtained. Our study results also demonstrate that zigzag channel can provide relatively better mixing, because the successive bending design can lead to secondary flow in the cross sectional directions due to Go¨rtler vortices generated from centrifugal effect as the flow negotiates the “turns” or “bends” of the channel, and this adds to mixing in addition to that due to aforementioned Coriolis effect. An analysis reveals that zigzag shape channel requires more pressure drop when compared with the straight channel in order to maintain the continuous throughflow due to the pressure/head loss as the flow encounters each bend and these losses become additive. This adds to the cost for the improved mixing from the Go¨rtler vortices.

Evaluation of the Mixing Performance of the Micromixers With Grooved or Obstructed Channels

2008 ◽  
Vol 130 (7) ◽  
Author(s):  
Yeng-Yung Tsui ◽  
Ching-Shiang Yang ◽  
Chung-Ming Hsieh
Keyword(s):  
Vertical Plane ◽  
Pressure Head ◽  
Fluid Mixing ◽  
Mixing Performance ◽  
Large Pressure ◽  
Fluid Concentration ◽  
Speed Up ◽  
Periodic Configuration ◽  
The Cost ◽  
Good Agreement

The mixing flows in microchannels were examined using numerical methods. To speed up fluid mixing, it is essential to generate lateral transport of mass. In this study, the mixing flow is disrupted by either placing grooves or block obstacles on the walls of the channels. Since the grooves or the blocks appear in a periodic configuration, the velocity is solved only in a section of the channel. With the repeating cycle of flow velocity field, the fluid concentration can be calculated throughout the entire length of the channel. Good agreement with experiments in the mixing performance justifies the present methodology. Two different channel configurations are under consideration: grooved channels and obstructed channels. The results reveal that with straight grooves, a well organized vortex flow is formed in the vertical plane along the groove, which leads to a helical flow in the channel. The mixing performance can be enhanced by having grooves on both the top and the bottom walls arranged in a staggered manner, by which the transversal velocity is largely increased. It is seen that the strength of the secondary flow and, thus, the mixing can be improved by suitably choosing geometric parameters of the groove, such as the depth, the width, and the oblique angle. It is also shown that the efficient mixing for the staggered herringbone type groove is due to the fluid stratification caused by the exchange of position of the resulted counter-rotating vortices. As for the obstructed channels, the flows are in essence two dimensional. Very strong transversal velocity can be produced by narrowing down the flow passage in the channel. However, the efficient mixing is obtained at the cost of large pressure head loss.

Socio-Economic Impact of Infused Iron Chelation Therapy in France: ISOSFER Study Results.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 3354-3354 ◽  
Author(s):  
Catherine Brun-Strang ◽  
Dora Bachir ◽  
Mariane De Montalembert ◽  
Isabelle Thuret
Keyword(s):  
Adverse Events ◽  
Chelation Therapy ◽  
Ferritin Level ◽  
Iron Chelation ◽  
Organ Damage ◽  
Total Direct Cost ◽  
Iron Chelation Therapy ◽  
Cross Sectional ◽  
Study Results ◽  
The Cost

Abstract Background: Patients suffering from β-thalassemia (TM), sickle cell disease (SCD), and myelodysplastic syndromes (MDS) undergoing chronic blood transfusions are at risk for iron overload which, if not treated by iron chelation therapy (ICT), can cause serious organ damage and reduce life expectancy. Deferoxamine (DFO) is the standard of care for the depletion of excess body iron. It has to be infused for 8–10 hours, 5–7 times a week. Although the clinical need for ICT is clearly established, less is known about the economic burden of DFO treatment. Aim: To estimate the total annual costs of DFO ICT in treatment centers in France. Methods: A cross-sectional study with a prospective recruitment. Among 278 consecutive patients receiving regular transfusions for TM, SCD or MDS who consulted between October 2005 and February 2006 in 24 French centers, 161 were on ICT. 124 patients were treated with DFO alone for more than 1 year. Among them, 67 aged 14 years or more agreed to participate. Resources used were collected through patient and physician questionnaires. Unit costs (2004/2005 €) were applied according to French economic guidelines. Results: DFO was administered via subcutaneous (sc) infusion for 70% of patients, mainly nightly and with a mean duration of 10 hours. Other ways of administering DFO included intravenous (iv) infusion (15%), sc bolus (9%) and combined sc and iv treatment (5%). Patient characteristics are summarized in the table below. TM (n=24) SCD (n=17) MDS (n=26) *Cardiac, liver and endocrine diseases, lens opacities, osteoporosis Median age (min-max), years 30 (15–70) 32 (14–57) 69 (45–85) Sex, M/F 11/13 6/11 14/12 Organ dysfunction potentially related to hemosiderosis* (%) 75 47 54 Ferritin level (median), ng/mL 1049 2653 2627 DFO nb/week (mean) 3.7 4.5 4 Dose (mean) 40 17 43 For all patients, the estimated mean weighted annual cost of infusions is 16009 € (SD ± 13867). Costs are similar for the three diseases. ICT delivery equipment (infusion set and pump) and nursing administration, drug cost, DFO adverse events monitoring, periodic exams and treatment of infused ICT-related adverse events represent respectively 56.5%, 38.5%, 0.3%, 3.7% and 0.9% of total direct cost. The estimated annual mean cost of the drug alone was 6160 € (SD ± 4145). Average cost for DFO adverse events management is low at 151.5€ (SD ± 1224), essentially due to one patient complication. Costs of periodic exams are also low due to the fact that exams are not strictly performed annually as recommended. These estimates of the total annual costs of DFO ICT are likely to be underestimating the overall cost of DFO therapy because treatment costs of the clinical consequences of poor adherence to DFO and lost productivity were not collected in the study. Conclusions: ISOSFER demonstrated that total direct costs of ICT are substantial and well exceed the cost of DFO alone. The cost of DFO administration constitutes a significant portion of the total cost of iron chelation (54%). These data are comparable to other analyses published from US (43% of the total costs, n=155) and Swiss (45%, n=17) databases.

ASSESSMENT OF SKILLED BIRTH ATTENDANTS REGARDING HELPING BABIES BREATH INTERVENTION TO IMPROVE NEWBORN CARE IN RURAL DISTRICT OF SINDH

1970 ◽  
Vol 7 (1) ◽  
pp. 48-53
Author(s):  
Sheh Mureed ◽  
Muhammad Hassan Gandro ◽  
Walid Hassan
Keyword(s):  
Newborn Care ◽  
Cross Sectional Study ◽  
Vital Role ◽  
Skilled Birth Attendants ◽  
Cross Sectional ◽  
Neonatal Deaths ◽  
Birth Attendants ◽  
Study Results ◽  
Knowledge And Practice ◽  
Labour Room

Background: Globally, 3.1 million newborn deaths occur every year out of these estimated 400,000 neonatal deaths occur in Pakistan. All neonatal deaths 99% take place in poorest region and countries of the world, usually within hours of birth; mostly the cause of neonatal deaths is hypoxia. To access knowledge and practice of SBAs regarding HBB and to access the availability of equipments required for HBB. Methods: Descriptive Cross-Sectional Study on SBAs as trained in HBB. All 46 SBAs trained on HBB working in Labour room eight rural Health centers, four Taluka, One district Head Quarter Health Facilities and thirteen Mlbcs of the district, were included in the sample for study. All 41 SBAs were trained on HBB participated in the study. Results: Mean age of 30 years. Out of total 41 participants 25 were working in B-EmoNC (61%), 3in C-EmoNC (7.3%) and 13 in mid wife laid birth Centre (MLBC) or birth station (31.7%). About 92.7% of participants said that main purpose of HBB training is to decrease the NMR by improving newborn care. Drying of newborn is 82.7%, hand washing is 95.12% and 85.3% of the study participants said that they gave 30-40 breaths per minutes. Cord clamp and pair of ties was accessible to 85% of participants versus 14.3% who reported it's not accessible. Almost one quarter (34.1%) participants have low knowledge and practice. Knowledge and training had significant effect on the overall practices of the skilled birth attendants for skilled birth deliveries and reduce the neonatal deaths (P <0.001). Conclusion: Tools play a vital role for the implication of the knowledge into practices and tools were available almost to every participant. Although few barriers also identified for the less application of the helping hand babies trainings in the community.

COMPARISION OF DENTAL SCORING SYSTEM WITH RADIOGRAPHIC SKELETAL SYSTEM IN AGE ESTIMATION

JKCD ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 9-11
Author(s):  
Sadaf Ambreen
Keyword(s):  
Age Estimation ◽  
Scoring System ◽  
Skeletal Age ◽  
Chronological Age ◽  
Age Group ◽  
Dental Age ◽  
Scoring Method ◽  
Cross Sectional ◽  
Study Results ◽  
Male Subjects

Objectives: To compare Demirjian Dental scoring method with Greulich-Pyle (GP) Skeletal method of age estimation in pubertal children. Materials and Methods: Sample of the study included 267 male healthy subjects of 11-16 years of age group.. Demirjian Scoring system was utilized to evaluate the orthopantomograms to assess their Dental age and the Hand-Wrist radiographs were analyzed to calculate the skeletal age by utilizing GP atlas. Chronological age was obtained from the date of birth of the subject .Both methods were compared with one another and with the chronological age. It was a cross-sectional study and only healthy male subjects without any clinical abnormalities were included in the study. Results: A total of 267 male subjects of 11-16 years of age group were assessed by Demirjian and Greulich Pyle Methods. Both were compared with Chronological Age. Data obtained was statistically analyzed and the Student “t” test was applied in the study population. The mean difference between Chronolgical age and dental age was 0.69years and that of chronological age and skeletal age was 0.87 years. It was observed from dental age assessment that it does not differ much from the skeletal age. Conclusion: It was concluded that Demirjian method of Age Estimation is more precise than Greulich Pyle method of Age Estimation. Furthermore both methods can be used selectively in Medicolegal cases to access bone age which can be easily correlated to chronological age.

Blood Analysis Requests of Patients’ and Clinical Reflections in Primary Care

2020 ◽  
Vol 9 (2) ◽  
pp. 96-102
Author(s):  
Zerrin Gamsizkan ◽  
Mehmet Ali Sungur ◽  
Yasemin Çayır
Keyword(s):  
Chronic Disease ◽  
Blood Test ◽  
Family Health ◽  
Cross Sectional Study ◽  
Blood Analysis ◽  
Primary Role ◽  
Cross Sectional ◽  
High Expectations ◽  
Blood Tests ◽  
Study Results

Aim: The aim of the study is to determine the factors that may affect the demands of patients who come with the request to have a blood test without any chronic disease or a planned examination check. Methods: The data of this descriptive, cross-sectional study, were collected with a questionnaire that was prepared to examine the opinions of the patients who claim to have a blood test by coming to the family health center without any complaints. Patients over 18 years of age, who did not have any chronic disease and had no scheduled examination appointments were included in the study. Results: A total of 278 patients who wanted to have a blood test within the 6-months period were included in the study. Female patients who wanted to have a blood test were significantly more than male patients. When we look at the causes of patients who wanted to have a blood test; 61.2% (n=170) patients stated that they are concerned about their health and 6.1% (n=17) stated that they were affected by media warnings. There was no significant relationship between the frequency of blood test requests of patients and their age, gender, education, and general health status. Conclusion: Patients with high expectations and anxiety may be more willing to perform blood tests at inappropriate intervals. Family physicians, whose primary role is preventive medicine, have consultancy and information duties in order to protect their patients from the risk of over-examination and diagnosis. Keywords: blood tests, patient, screening, routine diagnostic tests

HIV INFECTION AND SOME RELATED FACTORS IN FEMALE MASSAGE THERAPISTS IN QUANG NGAI PROVINCE

2015 ◽  
pp. 57-60
Author(s):  
Xuan Chuong Tran ◽  
Thi Thanh Hoa Le ◽  
Ngoc Van Nguyen ◽  
Thanh Nguyen
Keyword(s):  
Hiv Infection ◽  
Urban Areas ◽  
Risk Groups ◽  
Sexual Contact ◽  
Related Factor ◽  
Related Factors ◽  
Cross Sectional ◽  
Keywords Hiv ◽  
Study Results ◽  
Massage Therapists

Background: HIV/AIDS is still a dangerous infection in Vietnam and in the world. Studying of HIV infection and related factors in high risk groups, including female massage therapists is therefore very important. Aims: 1. To study the HIV infection in female massage therapists in Quang Ngai province. 2. To fine some related factors to HIV infection. Patients and methods: Female massage therapists working in Quang Ngai province. Cross-sectional, descriptive study. Results: The rate of HIV infection was 0.99%. Group older than 22 years old had higher rate of infection than group under 22 years old (1.80% vs 0.69%). The girls from urban areas or not using condom had higher rate of infection than group from rural or not using condom (1.57% vs 0.47% and 7.32% vs. 0.57%). Most of HIV infected belong to single or divorce groups. Conclusions: The rate of HIV infection in female massage therapists in Quang Ngai province was 0.99%. The HIV infection related factor was not using condom in sexual contact. Keywords: HIV, female massage therapists, Quang Ngai

STUDYING OF CHILDREN WITH MENTAL RETARDATION IN HUE CITY IN 2011

2012 ◽  
pp. 83-87
Author(s):  
Thi Minh Xuan Doan ◽  
Xuan Chuong Tran
Keyword(s):  
Mental Retardation ◽  
Cross Sectional Study ◽  
Learning Ability ◽  
Daily Activities ◽  
Sectional Study ◽  
Cross Sectional ◽  
Slow Development ◽  
Study Results

Children with mental retardation have low intelligence, slow thinking, low learning ability in comparison with the same age children. Objectives: 1. To determine the prevalence of children with mental retardation in Hue City. 2. To study some characteristics of children with mental retardation. Materials and methodes: All children with mental retardation in Hue city. Cross sectional study. Results: The prevalence of children with mental retardation (CMR) among children under 15 yrs is 0.23%, among disable children 38.16%. The highest prevalences ware in Phu Binh, Xuan Phu quarters (0.79 and 0.66%), lowest in Thuan Loc, Thuan Thanh quarters (0.03 and 0.06%). Children over 5 yrs old were 75.95%. Most of children have slow development in movement and daily activities. More than 78% have late walking, 84% have late speaking. Conclusions: The prevalence of children with mental retardation among children under 15 yrs is 0.23%, among disable children 38.16%. Most of children have slow development in movement and daily activities.

Validation of mathematical model of electrothermal calculation of DC catenary on the basis of scale model

2018 ◽  
Vol 77 (4) ◽  
pp. 222-229 ◽  
Author(s):  
A. V. Paranin ◽  
A. B. Batrashov
Keyword(s):  
Mathematical Model ◽  
Operating Conditions ◽  
Scale Model ◽  
Contact Network ◽  
Scaled Model ◽  
Cross Sectional ◽  
Current Collection ◽  
Topological Features ◽  
Study Results ◽  
Real Physical Process

The article compares the results of calculation of the finite element simulation of current and temperature distribution in the scale model of the DC catenary with the data of laboratory tests. Researches were carried on various versions of the structural design of catenary model, reflecting the topological features of the wire connection, characteristic of the DC contact network. The proportions of the cross-sectional area of the scaled model wires are comparable to each other with the corresponding values for real DC catenary. The article deals with the operating conditions of the catenary model in the modes of transit and current collection. When studying the operation of the scale catenary model in the transit mode, the effect of the structural elements on the current distribution and heating of the wires was obtained. Within the framework of the scale model, theoretical assumptions about the current overload of the supporting cable near the middle anchoring have been confirmed. In the current collection mode, the experimental dependences of the current in the transverse wires of the scale model are obtained from the coordinate of the current collection point. Using the model it was experimentally confirmed that in the section of the contact wire with local wear, not only the temperature rise occurs but also the current redistribution due to the smaller cross section. Thus, the current share in other longitudinal wires of the scale model increases and their temperature rises. Scale and mathematical models are constructed with allowance for laboratory clamps and supporting elements that participate in the removal of heat from the investigated wires. Obtained study results of the scale model allow to draw a conclusion about the adequacy of the mathematical model and its correspondence to the real physical process. These conclusions indicate the possibility of applying mathematical model for calculating real catenary, taking into account the uneven contact wear wire and the armature of the contact network.

scholarly journals Environmental Flow Assessment Considering Inter- and Intra-Annual Streamflow Variability under the Context of Non-Stationarity

Water ◽  
2018 ◽  
Vol 10 (12) ◽  
pp. 1737 ◽  
Author(s):  
Kang Ren ◽  
Shengzhi Huang ◽  
Qiang Huang ◽  
Hao Wang ◽  
Guoyong Leng
Keyword(s):  
Kendall Test ◽  
Environmental Flow ◽  
Mean Value ◽  
Test Method ◽  
Stationary Condition ◽  
Annual Streamflow ◽  
Riverine Ecosystems ◽  
Study Results ◽  
Wide Range ◽  
Streamflow Variability

A key challenge to environmental flow assessment in many rivers is to evaluate how much of the discharge flow should be retained in the river in order to maintain the integrity and valued features of riverine ecosystems. With the increasing impact of climate change and human activities on riverine ecosystems, the natural flow regime paradigm in many rivers has become non-stationary conditions, which is a new challenge to the assessment of environmental flow. This study presents a useful framework to (1) detect change points in runoff time series using two statistical methods (Mann-Kendall test method and heuristic segmentation method), (2) adjust data of the changed period against the original flow series into a stationary condition using a procedure of reconstruction; and (3) incorporate inter- and intra-annual streamflow variability with adjusted streamflow to evaluate environmental flow. The Jialing to Han inter-basin water transfer project was selected as the case study. Results indicate that a change point of 1994 was identified, revealing that the stationarity of annual streamflow series is invalid. The variations of reconstructed streamflow series are roughly consistent with original streamflow series, especially in the maximum/minimum values and rise/fall rates, but the mean value of reconstructed streamflow series is increased. The reconstructed streamflow series would further serve to eliminate the non-stationary of original streamflow, and incorporating the inter- and intra-annual variability would upgrade the ecosystem fitness. Selecting different criteria for the conservation of riverine ecosystems can have significantly different consequences, and we should not focus on the protection of specific objectives that will inevitably affect other aspects. This study provides a useful framework for environmental flow assessment and can be applied to a wide range of instream flow management approaches to protect the riverine ecosystem.

scholarly journals Indirect Health Effects of COVID-19: Unhealthy Lifestyle Behaviors during the Lockdown in the United Arab Emirates

2021 ◽  
Vol 18 (4) ◽  
pp. 1964
Author(s):  
Hadia Radwan ◽  
Mahra Al Kitbi ◽  
Hayder Hasan ◽  
Marwa Al Hilali ◽  
Nada Abbas ◽  
...  
Keyword(s):  
Physical Activity ◽  
United Arab Emirates ◽  
Lifestyle Change ◽  
Change Score ◽  
Lifestyle Changes ◽  
Lifestyle Behaviors ◽  
Negative Consequences ◽  
Unhealthy Lifestyle ◽  
Cross Sectional ◽  
Study Results

Background: Lockdown measures were implemented in many countries to limit the spread of the COVID-19 pandemic. However, such restrictions could precipitate unintended negative consequences on lifestyle behaviors. The main objective of this study was to investigate the prevalence and determinants of unhealthy behavior changes during the COVID-19 lockdown among residents of the United Arab Emirates (UAE). Methods: A cross-sectional web-based survey of adults residing in the UAE was carried out during lockdown (n = 2060). Using a multi-component questionnaire, the collected data included questions regarding the following lifestyle changes: Increased dietary intake, increased weight, decreased physical activity, decreased sleep, and increased smoking. An unhealthy lifestyle change score was calculated based on the number of unhealthy lifestyle changes each participant reported. In addition, sociodemographic and living conditions information was collected. Descriptive statistics as well as simple and multiple linear regression analyses were used to examine the prevalence and determinants of the unhealthy lifestyle changes considered in this study. Results: Among the unhealthy lifestyle changes examined, increased food intake was the most common (31.8%), followed by decreased physical activity (30%), increased weight (29.4%), decreased sleep (20.8%), and increased smoking (21%). In addition to identifying the correlates of each of the aforementioned lifestyle changes, the results of the multiple regression linear analyses revealed the following correlates for the overall unhealthy lifestyle change score: females (β = 0.32, CI: 0.22; 0.42), living in an apartment (β = 0.12, CI: 0.003; 0.23) and being overweight/obese (β = 0.24, CI: 0.15; 0.32) had higher scores, while older adults (>40 years) had lower scores (β = −0.23, CI: −0.34; −0.12). Conclusions: The COVID-19 lockdown has resulted in a high prevalence of unhealthy lifestyle behaviors and practices among UAE residents. The findings of this study provided the evidence base for officials to design interventions targeting high-risk groups and aiming to improve healthy lifestyle factors among residents during the pandemic.

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