Questions to the Article: Exploring the Shift in International Trends in Mobile Health Research From 2000 to 2020 (Preprint)

UNSTRUCTURED The article published on September 9, 2021, is well-written and of interest, but remains two questions that are required for clarifications, such as the ways (1) to construct the growth curve and (2) to determine the flashpoint(or, say, inflection point, IP) on the growth curve shown in Figure 3. The authors addressed that the year 2015 was a flashpoint on the curve(ie. y = 37e0.3062x, with R2=0.9935) and determined the flash point by the naked eye. Although numerous bibliometric analyses applied the cumulative publications to release information about the growth curve and the IP using a particular formula, none of such research proposed an appropriate way to determine the IP. Accordingly, we are motivated to propose an item response theory (IRT) model(IRT) to determine the IP on a given ogive curve and found that the IP is in 2017 instead of 2015 with R2=0.9797 rather than 0.9935 in the questionable article. Similarly, the real model coefficient and R2 are 0.2942 and 0.9954, respectively, if the growth curve is modeled by the formula(= 37ebx ) in Microsoft Excel using the Solver add-in tool demonstrated in this article. The ITR model used to determine the IP location on cumulative time-series data is recommended to future relevant studies, not merely limited to the bibliometric analysis.

A Numerical Investigation of Mixing Models in LES-FMDF for Compressible Reactive Flows

The filtered mass density function (FMDF) model has been employed for large-eddy simulations (LES) of compressible high-speed turbulent mixing and reacting flows. However, the mixing model remains a pressing challenge for FMDF methods, especially for compressible reactive flows. In this work, a temporal development mixing layer with two different convective Mach numbers, and , is used to investigate the mixing models. A simplified one-step reaction and a real hydrogen/air reaction are employed to study the mixing and turbulence-chemistry interaction. Two widely used mixing models, interaction by exchange with the mean (IEM) and Euclidean minimum spanning tree (EMST), are studied. Numerical results indicate that no difference is observed between the IEM and EMST models in simple reaction flows. However, for hydrogen/air reactions, the EMST model can predict the reaction more accurately in high-speed flow. For mixing models in compressible reactive flows, the requirement of localness preservation tends to be more essential as the convective Mach number increases. With the increase of compressibility, the sensitivity of the mixing model coefficient is reduced significantly. Therefore, the appropriate mixing model coefficient has a wider range. Results also indicate that a large error may result when using a fixed mixing model coefficient in compressible flows.

A Single-Institution Experience in the Use of Chest Radiographs for Hospitalized Children Labeled as Asthma Exacerbation

Background: Risks of diagnostic radiation have become more notable lately, particularly in young children with chronic medical conditions. This study reports on the cumulative radiation from chest radiographs in children with asthma. Its main purpose was to review our current practice and suggest minimizing the use of chest radiographs.Methods: The study was retrospective and conducted at a pediatric tertiary center. Eligibility criteria included children 2–15 y, admitted between January 2017 and December 2018 for asthma management.Results: Of the 643 children admitted as “asthma exacerbation,” 243 [40% females; age (mean ± SD) 5.4±3.3 y] met the study criteria for inclusion. Ninety-two (38%) children had a temperature of 38.8±0.7°C on the day of admission. Antibiotics were prescribed for 148 (61%) children, mainly for presumed pneumonia. Chest radiographs were requested for 214 (88%) children, mainly on the day of admission. Only 38 (18%) chest radiographs showed focal/multifocal pneumonia justifying antibiotic use. Significant predictors for requesting chest radiographs were antibiotic use for presumed pneumonia, lower oxygen saturation at presentation, and a requested blood culture. The rate of chest radiographs per year was negatively related to the child's age; the younger the child the higher the rate (model coefficient −0.259, P < 0.001). For children < 5 y, the rate of chest radiographs was 1.39 ± 1.21/y and radiation dose 0.028 ± 0.025 mSv/y. The corresponding rates for children ≥5 y were 0.78 ± 0.72/y and 0.008 ± 0.007 mSv/y, respectively (P < 0.001).Conclusion: Chest radiographs were commonly requested for children with asthma, especially younger children. Prospective studies are necessary to measure the impact of this practice on the children's health.

Permintaan Wisata Kelompok Pemuda ke Kota Bandung

This paper presents the results of research on tourist demands to the city of Bandung. The research objective is to study the demand function of tourists in the city of Bandung. Looking at the qualitative nature of tourism demand, this study examines it through the ordered logit model. Data obtained mainly from tourists visiting the city of Bandung. The estimation model repeatedly shows five factors that explain tourism demand, namely income, travel distance, leisure time owned by tourists, vehicles used to visit the city of Bandung, and the level of congestion in the city of Bandung. The biggest model coefficient is the comfort variable. Increasing leisure time one day will increase the chances of frequent categories of visits to the city of Bandung, 24,278 times greater than other categories. Klasifikasi JEL : Q21, Z23, C19 Abstrak. Makalah ini menyajikan hasil penelitian skripsi tentang permintaan wisatawan ke Kota Bandung. Tujuan penelitiannya adalah untuk mempelajari fungsi permintaan wisatawan di Kota Bandung. Melihat sifat kualitatif dari permintaan pariwisata, penelitian ini mengkajinya melalui model logit yang dipesan. Data diperoleh terutama dari wisatawan yang mengunjungi Kota Bandung. Model hasil estimasi berulang kali menunjukkan lima faktor yang menjelaskan permintaan pariwisata, yaitu pendapatan, jarak perjalanan wisata, waktu luang yang dimiliki oleh wisatawan, kendaraan yang digunakan untuk mengunjungi Kota Bandung, dan tingkat kemacetan di Kota Bandung. Koefisien model terbesar adalah variabel waktu luang. Menambah waktu luang suatu hari, akan memperbesar peluang kategori sering berkunjung ke Kota Bandung, 24.278 kali lebih besar dari kategori lainnya. Klasifikasi JEL : Q21, Z23, C19

Weighted average price management of sales under the given minimum volume of assets obligatory for realization

In this paper, we consider the construction of a sales management strategy for a highly liquid asset trading at the market. The proposed strategy goal is to maximize the weighted average price of sales. It is assumed that the market price follows a geometric Brownian motion process in which drift and volatility coefficients are random functions of time. The important feature of the given management is that the volumes of assets in the succession of buy and sell executed bargains are calculated exclusively on the basis of the observed market prices rather than on the model coefficient values. In contrast to the management proposed earlier in this study, obligatory realization of some minimum volume of assets on the given time period is demanded. Examples of real-world markets trade demonstrating the imposed constraints effect on the weighted average price values obtained within the constructed management are given.

A Single-Institution Experience in the Use of Chest Radiographs for Hospitalized Children Labelled as Asthma Exacerbation

Background: Risks of cancer have become more notable lately, especially for young children with a chronic condition such as atopy. This study reports on cumulative radiation from chest radiographs in children with asthma. Its main aims were to consider our current practice, and suggest minimizing chest radiograph use in this vulnerable people. Methods: The study was retrospective and conducted at tertiary center. Eligibility criteria included children 2-15 y who were admitted between January-2017 and December-2018 for asthma management. Results: Of 643 children who were admitted as ‘asthma exacerbation’, 243 (40% females; age [mean±SD] 5.4±3.3 y) met the study criteria for inclusion. Ninety-two (38%) children had temperature 38.8±0.7oC on the day of admission. Antibiotics were prescribed for 148 (61%) children, mainly for presumed pneumonia. Chest radiographs were requested for 214 (88%) children, mainly on the day of admission. Only 38 (18%) chest radiographs showed focal/multifocal pneumonia justifying antibiotic use. Significant predictors for requesting chest radiographs were antibiotic use for presumed pneumonia, lower oxygen saturation at presentation, and requesting blood culture. Rate of chest radiographs per year was negatively related to child’s age; the younger the child the higher the rate (model coefficient -0.259, P<0.001). For children <5 y, rate of chest radiographs was 1.39±1.21/y and radiation dose 0.028±0.025 mSV/y. The corresponding rates for children ≥5 y were 0.78±0.72/y and 0.008±0.007 mSV/y, respectively (P<0.001). Conclusion: Chest radiographs were commonly requested for children with asthma, especially the young ones. Prospective studies are necessary to measure the impact of this practice on their health.

Evaluation of respiratory parameters in patients with chronic obstructive lung disease during physical exercises

Aim. To study the relationship between the indicators of dynamic capnography and pulse oximetry with the indicators of the 6-minute walk test (6MWT) in patients with chronic obstructive pulmonary disease (COPD). Materials and methods. 67 patients of both sexes were examined: 45 patients with COPD (age 60.02.74 years) and 25 patients of the control group (age 47.603.46 years). The study of the functional capabilities of the patients respiratory system was carried out before, during and after the 6MWT on the equipment LifeSense LS1-9R capnograph-pulse oximeter (MedAir AB). Results and discussion. In the comparison group, the parameters of dyspnea at rest were higher than the control group (p0.05), the spirometry indices were significantly lower (p0.05). Shortness of breath as a reason for stopping/slowing down the pace during the 6MWT was noted by patients of both groups (p0.05). When analyzing the PETCO2 trend graphs, periodic breathing (PВ) was revealed. In the group of patients with COPD, signs of PВ in the analysis of the PETCO2 trend were found in 80.95% (p0.05). Regression analysis of Cox proportional risks of mortality in patients with COPD revealed the prognostic value of the following parameters of a comprehensive assessment of the patient: body mass index (BMI), BODE index, dyspnea index on the mMRS scale, Borg, forced expiratory volume in 1 second (FEV1), index Tiffno, signs of PВ, distance 6MWT, signs of PВ and desaturation during 6MWT. At the same time, the total contribution of these indicators to the risk of a lethal event was assessed (p=0.003). Conclusion. When analyzing the correlation dependence, it was revealed that the presence of PВ was a prognostically unfavorable sign in patients with COPD. Predictors of an unfavorable course of COPD were BMI (23.0 kg/m2), BODE index, dyspnea indices on the mMRS, Borg, FEV1 scales, Tiffnos index, signs of PH, distance 6MST, signs of PD and desaturation during 6MST (reliability of the model coefficient p=0.003) in terms of forecast.

Robust regression with compositional covariates including cellwise outliers

We propose a robust procedure to estimate a linear regression model with compositional and real-valued explanatory variables. The proposed procedure is designed to be robust against individual outlying cells in the data matrix (cellwise outliers), as well as entire outlying observations (rowwise outliers). Cellwise outliers are first filtered and then imputed by robust estimates. Afterwards, rowwise robust compositional regression is performed to obtain model coefficient estimates. Simulations show that the procedure generally outperforms a traditional rowwise-only robust regression method (MM-estimator). Moreover, our procedure yields better or comparable results to recently proposed cellwise robust regression methods (shooting S-estimator, 3-step regression) while it is preferable for interpretation through the use of appropriate coordinate systems for compositional data. An application to bio-environmental data reveals that the proposed procedure—compared to other regression methods—leads to conclusions that are best aligned with established scientific knowledge.