A study of radiative heat transfer from a spherical layer

The problem of radiative heat transfer from a spherical layer of absorbing-emitting gas has been studied. First, the medium is assumed to be gray and then nongray. A thorough survey of literature from fields other than heat transfer, such as astrophysics and neutron transport has been made to stimulate further interest in this important area. To gain some insight into the effect of various parameters on the heat transfer, simple physical situations involving isothermal medium are considered. Comparison of the results obtained for the flux from the spherical and planar layers reveal that the curvature becomes increasingly important as the inner to outer optical radii ratio decreases. The study of a particular nonisothermal case shows that the temperature variations are important and cannot be neglected. In the study of the nongray problem, a simplified rectangular model for the spectral absorption coefficient is first considered. The expressions developed for the simplified rectangular model turns out to be similar to the expressions for the gray analysis. With a small amount of additional computational time one can obtain the results for the simplified rectangular model. Carbon monoxide example is studied in order to illustrate how the rectangular model can be used to analyze radiative heat transfer in a nongray gas. The results of this example reveals that the influence of the \u27windows\u27 is quite profound, thus exposing the limitations of the gray analysis. In order to determine the effect of line or band shape on the radiative transfer, five different models for the absorption coefficient representing the rectangular, triangular, Doppler, exponential and Lorentz profiles are considered. The results obtained for the dimensionless flux reveal that the rectangular profile has the smallest numerical value of all the profiles. The effect of the wings of the Doppler, exponential and Lorentz profiles is evident only for large values of optical thickness. The limiting cases of the functions on which the expressions for the local radiative flux (both from gray and nongray medium) depends are also studied. All the results (except for carbon monoxide example) reported graphically as well as in tabular form in this study are obtained using double precision --Abstract, pages ii-iii

Meningkatkan Hasil Belajar Pokok Bahasan Tata Surya melalui Penerapan Model Pembelajaran Kooperatif Tipe (NHT)

Penelitian ini dilandasi oleh rendahnya hasil belajar pokok bahasan tata surya siswa kelas VII C di SMP Negeri 1 Wawotobi yang disebabkan oleh kurangnya minat siswa dalam belajar sehingga siswa masih pasif dalam kegiatan belajar mengajar di kelas. Siswa merasa pembelajaran ini kurang menarik karena belum diterapkannya model pembelajaran yang bervariatif, kreasi, inovatif, dan menyenangkan dalam pembelajaran ini. Penelitian ini bertujuan untuk meningkatkan hasil belajar siswa dengan menerapkan model pembelajaran kooperatif tipe NHT. Pengumpulan data dilakukan dengan menggunakan tes evaluasi observasi untuk mengetahui sejauh mana tingkat aktivitas guru dan siswa dalam melaksanakan pembelajaran dengan menggunakan metode kooperatif tipe NHT. Hasil belajar siswa pada siklus I mencapai persentase ketuntasan klasikal 56,25% dan meningkat pada siklus II ketuntasan klasikal menjadi 87,5%. Kesimpulan pada penelitian ini adalah penerapan model pembelajaran kooperatif tipe NHT dapat meningkatkan hasil belajar siswa pada mata pelajaran IPA pokok bahasan tata surya kelas VII C SMP Negeri 1 Wawotobi

Implementasi Cross Layer Enchenched Packet Scheduling Paket Multimedia Untuk Jaringan Ofdm Uplink Di Bawah Redaman Hujan

In the previous network, optimization is often done on a separate layer and the result is less than optimal. Therefore, developed a new scheme to combine multiple layers of network protocol called Cross-Layer, for example in the physical layer and link layer. In this final project will be evaluated applying Cross-Layer Optimization methods with emphasis on the evaluation of scheduling schemes of OFDM uplink transmission of multimedia data packets using Enhanced Cross-Layer Packet Scheduling (CEPS) under rain attenuation. The results showed that the use of scheduling CEPS give effect to video and voice traffic is real-time priority in scheduling and packet loss and delay as small as possible while the data traffic (FTP) with a delay that can be tolerated can log buffer considering fairness and physical layer conditions

Centrosymmetric-noncentrosymmetric Structural Phase Transition in Quasi one-dimensional compound, (TaSe4_4)3_3I

(TaSe$_4$)$_3$I, a compound belonging to the family of quasi-one-dimensional transition-metal tetrachalcogenides, has drawn significant attention due to a recent report on possible coexistence of two antagonistic phenomena, superconductivity and magnetism below 2.5~K (Bera et. al, arXiv:2111.14525). Here, we report a structural phase transition of the trimerized phase at temperature, $T~\simeq$~145~K using Raman scattering, specific heat, and electrical transport measurements. The temperature-dependent single-crystal X-ray diffraction experiments establish the phase transition from a high-temperature centrosymmetric to a low-temperature non-centrosymmetric structure, belonging to the same tetragonal crystal family. The first-principle calculation finds the aforementioned inversion symmetry-breaking structural transition to be driven by the hybridization energy gain due to the off-centric movement of the Ta atoms, which wins over the elastic energy loss.Comment: 11 pages, 5 figures, Under review as a regular articl

Geo-spatial reporting for monitoring of household immunization coverage through mobile phones: Findings from a feasibility study

Background: The addition of Global Positioning System (GPS) to a mobile phone makes it a very powerful tool for surveillance and monitoring coverage of health programs. This technology enables transfer of data directly into computer applications and cross-references to Geographic Information Systems (GIS) maps, which enhances assessment of coverage and trends.Objective: Utilization of these systems in low and middle income countries is currently limited, particularly for immunization coverageassessments and polio vaccination campaigns. We piloted the use of this system and discussed its potential to improve the efficiency of field-based health providers and health managers for monitoring of the immunization program.Methods: Using 30×7 WHO sampling technique, a survey of children less than five years of age was conducted in random clusters of Karachi, Pakistan in three high risk towns where a polio case was detected in 2011. Center point of the cluster was calculated by the application on the mobile. Data and location coordinates were collected through a mobile phone. This data was linked with an automated mHealth based monitoring system for monitoring of Supplementary Immunization Activities (SIAs) in Karachi. After each SIA, a visual report was generated according to the coordinates collected from the survey.Result: A total of 3535 participants consented to answer to a baseline survey. We found that the mobile phones incorporated with GIS maps can improve efficiency of health providers through real-time reporting and replacing paper based questionnaire for collection of data at household level. Visual maps generated from the data and geospatial analysis can also give a better assessment of the immunizationcoverage and polio vaccination campaigns.Conclusion: The study supports a model system in resource constrained settings that allows routine capture of individual level data through GPS enabled mobile phone providing actionable information and geospatial maps to local public health managers, policy makers and study staff monitoring immunization coverage

Usability and acceptability of a mobile app for behavior change and to improve immunization coverage among children in Pakistan: A mixed-methods study

Background: Pakistan\u27s immunization uptake rates are still significantly lower than anticipated despite several initiatives. Lack of awareness, forgetting about vaccination schedule, and vaccine misconception/misinformation are a few of the major drivers that mitigate the rates of immunization. The current COVID-19 pandemic emphasizes the importance of immunization. The significant reductions in regular childhood vaccination during pandemic have increased the risk of outbreaks of vaccine-preventable diseases. Concerns among parents over possibly exposing their children to COVID-19 during child visits may have contributed to the reported declines. Innovative and cost-effective mHealth interventions must be implemented in order to address the problem of inadequate immunization rates. In addition, it is also critical to understand the end user needs in order to reflect on the highly relevant essence of the customized healthcare experience.Objective: The aim of this study was to learn about caregivers\u27 attitudes toward the usability and acceptability of behavior-change smartphone applications (mobile phones) for improving immunization coverage in Pakistan.Methods: A mixed-method design was employed for this study. The study was conducted at Aga Khan University, Hospital. Parents visiting the Community Health Center for 6-week vaccination of their children were recruited. The study was conducted in two stages. Stage 1 consisted of qualitative interviews that grasped the parent\u27s attitudes and challenges to immunization, as well as their acceptability and accessibility of the smartphone-based behavior-change application to increase vaccine uptake. Stage 1 was followed by stage 2, in which data were collected through a questionnaire designed by using data from qualitative interviews.Results: The majority of participants agreed that immunization serves an important role in protecting their child from illnesses that cause morbidity and mortality. Almost all of them emphasized the importance of using a pre-appointment method at vaccination center in order to reduce the waiting time. Furthermore, participants were also interested in AI-based behavior modification applications related to immunization. They also wanted to have applications in their native language for better understanding and communication of related information. In our study, approximately 95.2 percent of participants agreed to accept SMS immunization updates, which was also reasonably high. Lastly, the majority of them identified forgetfulness as a significant contributor to regular immunization.Conclusion: To enhance the uptake of childhood vaccines, overall vaccination rates, and overcome barriers related to vaccination coverage, cost-effective and user-friendly mHealth AI-based smart phone applications are required to raise awareness regarding the continuation of vaccination service and the importance of timely vaccination. Parents\u27 experiences and attitudes must be considered while designing and evaluating the efficacy of mHealth-based interventions

Effect of mobile phone text message reminders on routine immunization uptake in Pakistan: randomized controlled trial

Background: Improved routine immunization (RI) coverage is recommended as the priority public health strategy to decrease vaccine-preventable diseases and eradicate polio in Pakistan and worldwide.Objective: The objective of this study was to ascertain whether customized, automated, one-way text messaging (short message service, SMS) reminders delivered to caregivers via mobile phones when a child is due for an RI visit can improve vaccination uptake and timelines in Pakistan.Methods: This was a randomized controlled trial, conducted in an urban squatter settlement area of Karachi, Pakistan. Infants less than 2 weeks of age with at least one family member who had a valid mobile phone connection and was comfortable receiving and reading SMS text messages were included. Participants were randomized to the intervention (standard care + one-way SMS reminder) or control (standard care) groups. The primary outcome was to compare the proportion of children immunized up to date at 18 weeks of age. Vaccine given at 6, 10, and 14 weeks schedule includes DPT-Hep-B-Hib vaccine (ie, diphtheria, pertussis, and tetanus; hepatitis B; and Haemophilus influenza type b) and oral poliovirus vaccine (OPV). Data were analyzed using chi-square tests of independence and tested for both per protocol (PP) and intention-to-treat (ITT) analyses.Results: Out of those approached, 84.3% (300/356) of the participants were eligible for enrollment and 94.1% (318/338) of the participants had a working mobile phone. Only children in the PP analyses, who received an SMS reminder for vaccine uptake at 6 weeks visit, showed a statistically significant difference (96.0%, 86/90 vs 86.4%, 102/118; P=.03).The immunization coverage was consistently higher in the intervention group according to ITT analyses at the 6 weeks scheduled visit (76.0% vs 71.3%, P=.36). The 10 weeks scheduled visit (58.7% vs 52.7%, P=.30) and the 14 weeks scheduled visit (31.3% vs 26.0%, P=.31), however, were not statistically significant.Conclusions: Automated simple one-way SMS reminders in local languages might be feasible for improving routine vaccination coverage. Whether one-way SMS reminders alone can have a strong impact on parental attitudes and behavior for improvement of RI coverage and timeliness needs to be further evaluated by better-powered studies and by comparing different types and content of text messages in low-and middle-income countries (LMICs)

Current challenges of digital health interventions in Pakistan: Mixed methods analysis

Background: Digital health is well-positioned in low and middle-income countries (LMICs) to revolutionize health care due, in part, to increasing mobile phone access and internet connectivity. This paper evaluates the underlying factors that can potentially facilitate or hinder the progress of digital health in Pakistan.Objective: The objective of this study is to identify the current digital health projects and studies being carried out in Pakistan, as well as the key stakeholders involved in these initiatives. We aim to follow a mixed-methods strategy and to evaluate these projects and studies through a strengths, weaknesses, opportunities, and threats (SWOT) analysis to identify the internal and external factors that can potentially facilitate or hinder the progress of digital health in Pakistan.Methods: This study aims to evaluate digital health projects carried out in the last 5 years in Pakistan with mixed methods. The qualitative and quantitative data obtained from field surveys were categorized according to the World Health Organization\u27s (WHO) recommended building blocks for health systems research, and the data were analyzed using a SWOT analysis strategy.Results: Of the digital health projects carried out in the last 5 years in Pakistan, 51 are studied. Of these projects, 46% (23/51) used technology for conducting research, 30% (15/51) used technology for implementation, and 12% (6/51) used technology for app development. The health domains targeted were general health (23/51, 46%), immunization (13/51, 26%), and diagnostics (5/51, 10%). Smartphones and devices were used in 55% (28/51) of the interventions, and 59% (30/51) of projects included plans for scaling up. Artificial intelligence (AI) or machine learning (ML) was used in 31% (16/51) of projects, and 74% (38/51) of interventions were being evaluated. The barriers faced by developers during the implementation phase included the populations\u27 inability to use the technology or mobile phones in 21% (11/51) of projects, costs in 16% (8/51) of projects, and privacy concerns in 12% (6/51) of projects.Conclusions: We conclude that while digital health has a promising future in Pakistan, it is still in its infancy at the time of this study. However, due to the coronavirus disease 2019 (COVID-19) pandemic, there is an increase in demand for digital health and implementation of health outcomes following global social distancing protocols, especially in LMICs. Hence, there is a need for active involvement by public and private organizations to regulate, mobilize, and expand the digital health sector for the improvement of health care systems in countries

Monitoring for airborne respiratory viruses in a general pediatric ward in Singapore

There is an increasing body of evidence suggesting that transmission of respiratory viruses occurs through the inhalation of virus-laden particles. Our study describes the use of an aerosol sampling system to monitor the prevalence of airborne viruses in a hospital setting. Using SKC AirCheck Touch pumps, with National Institute for Occupational Safety and Health (NIOSH) bioaerosol samplers and SKC filter cassette blanks, 28 aerosol samples were collected in a hospital ward in Singapore. Following DNA/RNA extraction, real-time RT-PCR/PCR was used for the detection of influenza A, B and D viruses, coronaviruses, enteroviruses, and adenoviruses. Airborne virus was detected in nine (32%) of 28 samples. Among the nine positive samples, eight were PCR-positive for adenovirus and one for influenza A virus. Our data suggest that bioaerosol sampling could be valuable in monitoring for airborne respiratory viruses in clinical environments to better understand the risk of infection during a hospital visit

Enhanced coercivity and emergence of spin cluster glass state in 2D ferromagnetic material Fe3GeTe2

Two-dimensional (2D) van der Waals (vdW) magnetic materials with high coercivity and high $T_\text{C}$ are desired for spintronics and memory storage applications. Fe$_3$GeTe$_2$ (F3GT) is one such 2D vdW ferromagnet with a reasonably high $T_\text{C}$, but with a very low coercive field, $H_\text{c}$ ($\lesssim$100~Oe). Some of the common techniques of enhancing $H_\text{c}$ are by introducing pinning centers, defects, stress, doping, etc. They involve the risk of undesirable alteration of other important magnetic properties. Here we propose a very easy, robust, and highly effective method of phase engineering by altering the sample growth conditions to greatly enhance the intrinsic coercivity (7-10 times) of the sample, without compromising its fundamental magnetic properties ($T_\text{C}\simeq$210K). The phase-engineered sample (F3GT-2) comprises of parent F3GT phase with a small percentage of randomly embedded clusters of a coplanar FeTe (FT) phase. The FT phase serves as both mosaic pinning centers between grains of F3GT above its antiferromagnetic transition temperature ($T_\text{C1}\sim$70~K) and also as anti-phase domains below $T_\text{C1}$. As a result, the grain boundary disorder and metastable nature are greatly augmented, leading to highly enhanced coercivity, cluster spin glass, and meta-magnetic behavior. The enhanced coercivity ($\simeq$1~kOe) makes F3GT-2 much more useful for memory storage applications and is likely to elucidate a new route to tune useful magnetic properties. Moreover, this method is much more convenient than hetero-structure and other cumbersome techniques.Comment: 12 pages, 11 figure