Analysis of the Number of Tests, the Positivity Rate, and Their Dependency Structure during COVID-19 Pandemic

BackgroundApplying recent advances in medical instruments, information technology, and unprecedented data sharing into COVID-19 research revolutionized medical sciences, and causes some unprecedented analyses, discussions, and models. MethodsModeling of this dependency is done using four classes of copulas: Clayton, Frank, Gumbel, and FGM. The estimation of the parameters of the copulas is obtained using the maximum likelihood method. To evaluate the goodness of fit of the copulas, we calculate AIC. All computations are conducted on Matlab R2015b, R 4.0.3, Maple 2018a, and EasyFit 5.6, and the plots are created on software Matlab R2015b and R 4.0.3. ResultsAs time passes, the number of tests increases, and the positivity rate becomes lower. The epidemic peaks are occasions that violate the stated general rule -due to the early growth of the number of tests. If we divide data of each country into peaks and otherwise, about both of them, the rising number of tests is accompanied by decreasing the positivity rate. ConclusionThe positivity rate can be considered a representative of the level of the spreading. Approaching zero positivity rate is a good criterion to scale the success of a health care system in fighting against an epidemic. We expect that if the number of tests is great enough, the positivity rate does not depend on the number of tests. Accordingly, the number and accuracy of tests can play a vital role in the quality level of epidemic data. Key messages- In a country, increasing the positivity rate is more representative than increasing the number of tests to warn about an epidemic peak. - Approaching zero positivity rate is a good criterion to scale the success of a health care system in fighting against an epidemic. - Except for the first half of the epidemic peaks, in a country, the higher number of tests is associated with a lower positivity rate. - In countries with high test per million, there is no significant dependency between the number of tests and positivity rate.

Forecasting new daily confirmed cases infected by COVID-19 in Italy from April 9th to May 18th 2020

We aim at forecasting the outbreak of COVID-19 in Italy by using a two-part time series to model the daily relative increments. Our model is based on the data observed from 22 February to 8 April 2020 and its objective is forecasting 40 days from 9 April to 18 May 2020. All the calculations, simulations, and results in the present paper have been done in MatLab R2015b. The average curve and 80% upper and lower bounds are calculated based on 100 simulations of the fitted models. According to our model, it is expected that by May 18th, 2020, the relative increment (RI) falls to the interval of 0.31% to 1.24% (average equal to 0.78%). During the last three days of the studied period, the RI belonged to the interval 2.5% to 3%. Accordingly, It is expected that the new daily confirmed cases face a decreasing to around 1900 on average. Finally, our prediction establishes that the cumulative number of confirmed cases reaches 237635 (with 80% confidence interval equal to [226340 248417] by May 18th, 2020.

Prolonged Lifetime of Perovskite Solar Cells Using a Moisture-Blocked and Temperature-Controlled Encapsulation System Comprising a Phase Change Material as a Cooling Agent.

Although the power conversion efficiency of perovskite solar cells (PSCs) reached up to 25% that made them comparable to the commercial solar cells, they are facing issues toward commercialization, especially their short lifetime. Remarkably, the most important key factors that regulate the durability of the devices are moisture, light, and heat. In this work, prolonging the device lifetime is focused by designing a flexible moisture-blocked and temperature-controlled encapsulation system. In this regard, a thermally adjusted phase change material is embedded in a polymer encapsulation layer to avoid the moisture diffusion, rapid temperature fluctuation, and undesired crystalline phase change of the perovskite layer in the PSCs under the operation condition. As a result, a 2 year stable device is achieved, whereas the reference device loses more than 50% of its performance after 10 days. Surprisingly, the charge transport resistance and recombination rate show no significant change during 450 days of storage, which confirms no increase in the defect density.

High Power UV-Light Irradiation as a New Method for Defect Passivation in Degraded Perovskite Solar Cells to Recover and Enhance the Performance.

Although the power conversion efficiency (PCE) of perovskite solar cells (PSCs) reached up to 23%, their short lifetime and fast degradation still remain as the main challenges. In this work, a new facile optical method based on the high power UV-irradiation is presented for the recovery of the degraded PSCs. Addition to the full recovery of the performance, about 20% PCE enhancement and hystersis reduction are also achieved by UV-irradiation. UV-treatment causes modifications in both the bulk properties of the perovskite layer and the energy equilibrium at the interfaces. It is shown that UV-treatment effectively passivates the surface and grain boundaries defects in different types of the devices comprising normal and inverted configurations that is confirmed by the reduction of the density of defect states (DOS). It is proposed that UV-light passivates the shallow and deep defects by dissociation of adsorbed hydroxyl groups and water molecules during the device storage.

Anthropometric Indices from Primary to High School in the West of Iran: Epidemiologic Trends

Examining the trend of anthropometric indices in children and adolescents in each region can be highly beneficial in providing effective strategies to improve the status of their growth. This study was conducted with the aim of determining the trend of anthropometric indices in students from primary to high school in the west of Iran. Data were collected using a demographic questionnaire and health certificates for anthropometric information of primary school students, and current anthropometric measurements with scale for high school students. Then, all of the data were analyzed in AnthroPlus and SPSS software. Of the 731 students, 350 were female and 381 were male. Mean height Z-score to age showed a significant reduction from primary to high school (from +0.0386 to −0.27416), and mean body mass index Z-score to age showed a significant increase (from −0.3916 to +0.1826). Prevalence of stunting and overweight/obesity in high school was 1.4 and 2.5 times higher than primary school, respectively, but the prevalence of wasting reduced by 2.3 fold. Girls were more affected by the increased trend of obesity and stunting compared to boys. Nutritional transition was evident in students. Healthcare policy-makers should design and implement a comprehensive health strategy to deal with this situation, especially in girls.

Comparison of 3 Nutritional Questionnaires to Determine Energy Intake Accuracy in Iranian Adults

A precision instrument is required to assess the nutritional status. This study was conducted on comparison of 3 nutritional questionnaires to determine energy intake (EI) accuracy in adults in Ravansar Non-Communicable Chronic Disease (RaNCD) cohort study. This cross-sectional study was conducted on 118 of participant's RaNCD. EI was evaluated with 3 questionnaires including food frequency questionnaire (FFQ), 24-hours recall (24HR), and food habits questionnaire (FHQ). Resting metabolic rate (RMR) was measured using indirect calorimetry. We used EI/RMR cut off to evaluate EI reporting status. The mean ± standard deviation of age in men and women were 44.1 ± 6.5 and 43.7 ± 5.25 respectively and 50.8% of participants were men. Among 3 EI estimating questionnaires, FFQ was more accurate than 2 other questionnaires (67.8%). We observed that implausible reporters of 24HR were likely overweight (p < 0.005) but we did not observe a significant difference between EI reporting of FFQ and FHQ with participants' body composition. Our finding showed that EI underreporting of 24HR and FHQ were high. Under reporters were seemed to be overweight. Therefore, these results suggested that among 3 nutritional questionnaires the FFQ was an appropriate approach to determine EI in this population due to plausible EI reporting was higher than 2 other nutritional questionnaires (24HR and FHQ).

Dietary Diversity Score and Its Related Factors among Employees of Kermanshah University of Medical Sciences

Dietary diversity score (DDS) is known as an indicator of food quality. Dietary diversity can promote health status. The aim of this study was determined DDS and its related factors in Kermanshah University of Medical Sciences (KUMS) employees. This cross-sectional study was conducted on 190 employees of KUMS in 2015. According to the population of KUMS centers which were selected randomly (Paramedical, Public Health faculties, Imam Reza Hospital and province health center), subjects were selected by convenience sampling method. Food frequency questionnaire (FFQ) was used to calculate DDS. Foods were divided into 5 main groups: grains, vegetables, fruits, meat, and dairy products. The main groups had 23 subgroups. Total DDS divided to 4 quartiles: less than 3.0, 3.0–5.5, 5.6–8.5, and more than 8.5. Anthropometric parameters including: weight, height, waist circumference (WC), and hip circumference were measured. Data were analyzed by Kolmogorov-Smirnov test, χ² test, and analysis of variance (ANOVA) test with SPSS 20 software (IBM Corp., Chicago, IL, USA). The mean ± standard deviation of DDS and body mass index (BMI) were 5.68 ± 1.73 and 25.1 ± 3.42 kg/m², respectively. The average of the waist-to-hip ratio (WHR) in men and women was 0.92 ± 0.04 and 0.86 ± 0.06, respectively. There was statistically significant difference between DDS and self-reported economic status (p < 0.022). No significant difference was observed between DDS and BMI or WC. However, significant negative correlation was observed between DDS and WHR in men (p < 0.019). This study showed that DDS had a negative correlation with the WHR. Therefore, dietary diversity may improve health status by effect on fat distribution in body.

Immunofluorescence assay and PCR analysis of cryptosporidium oocysts and species from human feacal specimens.

BACKGROUND: Cryptosporidium spp. is a widespread protozoan parasite involving humans and animals. OBJECTIVES: This study was carried out to evaluate the immunofluorescence assay (IFA) and PCR results for more accurate diagnosis of faecal specimens. PATIENTS AND METHODS: Forty six faecal human specimens of Cryptosporidium oocysts were examined by PCR and IFA in Calgary, Canada. In statistical analysis, sensitivity and positive predictive value were detected by IFA. RESULTS: Among 46 faecal samples, 9 (19.6%) were IFA-positive and 10 (21.7%) PCR-positive. Faecal smears of both PCR- and IFA-positive shown that the reproducibility was 90.9% for PCR-DNA and 81.8% for IFA. In Our findings, PCR -DNA showed that diagnosis cryptosporidiosis 2.1% was more sensitive than IFA. Two different oocysts sizes were visualized by IF microscopy which belonged to different species. Furthermore, PCR analysis with primers against the 18S rRNA gene indicated two genotypes of C. hominis and C. parvum, 500-650 base pairs (bp). In this study, the golden standard was the PCR. In statistical analyses, IFA had positive predictive value (PPV) of 81.8% with 81.8% sensitivity, whereas negative predictive value (NPV) was 1% with 0.97% specificity. CONCLUSIONS: PCR showed more sensitivity than IFA for tracking Cryptosporidium oocysts as well as detection of species in faecal human specimens.

High frequency of Helicobacter pylori DNA in drinking water in Kermanshah, Iran, during June-November 2012.

To gain a better understanding of transmission and selecting appropriate measures for preventing the spread of Helicobacter pylori, the aim of this study was to investigate the prevalence of H. pylori in drinking water samples in Kermanshah, Iran. Drinking water samples were collected from around Kermanshah and filtered through 0.45 µm nitrocellulose filters. The bacterial sediment was subjected to DNA extraction and polymerase chain reaction (PCR) for H. pylori detection using newly designed primers targeted at the conserved region of the ureC gene. The overall detection rates for H. pylori DNA in the water samples were 56% (66/118) with a frequency of 36% (25/70) in tap water samples and 85% (41/48) in wells. The detection limit was 50 bacteria per liter of filtered water and a pure H. pylori DNA copy number of 6 per reaction. Based on the evidence we may suggest that recontamination occurred and H. pylori entered into the water piping system through cracked or broken pipes or was released from established H. pylori biofilms on pipes. In conclusion, a high prevalence of H. pylori was detected in drinking water samples that strengthens the evidence of H. pylori transmission through drinking water.

Antioxidant status in patients with psoriasis.

Psoriasis is a chronic inflammatory skin disease with an unknown aetiology that has been associated with abnormal plasma lipid metabolism and oxidative stress. There are controversial results in the previous studies investigating oxidant/antioxidant systems in psoriasis.The aim of this work was to evaluate the plasma levels of malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT), total bilirubin (T. Bili), direct bilirubin (D. Bili), uric acid (UA), apolipoproteins (ApoA1 and ApoB), Lp(a) and activities of paraxonase 1 (PON1) in 100 patients with psoriasis and 100 controls, and to look for a correlation between these parameters in psoriasis.PON1, bilirubin and UA were measured spectrophotometrically, MDA by the high-performance liquid chromatography method, apolipoproteins and Lp(a) by immunoprecipitation assays, and lipid and other biochemical parameters were determined by routine laboratory methods.In patients with psoriasis, there was a significant decrease in PON1, SOD and CAT activities (P < 0.05) and an increase in MDA levels (P < 0.01). Also, the levels of bilirubin (total and direct) and UA were decreased in patients with psoriasis but were not significant (P > 0.05).These results suggest that psoriasis was in a state of oxidative stress and that the protective effects of high-density lipoprotein against atherosclerosis may be dependent on PON1 activity. Moreover, there is a negative correlation between antioxidant with Lp(a), apoB and MDA levels, suggesting that subjects with higher levels of Lp(a) and apoB and lower levels of antioxidant are more exposed to oxidative damage. These findings may explain in part the reported increase in cardiovascular mortality in psoriasis.

Celiac disease: Serologic prevalence in patients with irritable bowel syndrome.

BACKGROUND: The prevalence of irritable bowel syndrome (IBS) in the community is 10%-20% and have symptom based diagnostic criteria. Many symptoms of celiac disease (CD) with 1% prevalence in some communities can mimic IBS. Sensitive and specific serologic tests of CD can detect asymptomatic cases. The purpose of this study was to compare the level of anti-tissue-transglutaminase (tTG) IgA in IBS patients and controls group. MATERIALS AND METHODS: This case-control study was performed at a University hospital in which 107 patients with IBS who met the Rome II criteria for their diagnosis were compared with 126 healthy age and sex-matched controls. Both groups were investigated for CD by analysis of their serum tTG IgA antibody with human recombinant antigen. Titers were positive containing over 10u/ml and borderline if they were between 4 and 10 u/ml. RESULT: 86 percent of IBS patients were female. The mean antibody level was 0.837 u/ml in IBS group and 0.933 u/ml in control group without any significant difference. DISCUSSION AND CONCLUSION: Results of this study may intensify disagreement on the situation of CD in IBS patients.