Surgical theater is one of the most expensive hospital sources that a high percentage of hospital admissions are related to it. Therefore, efficient planning and scheduling of the operating rooms ...(ORs) is necessary to improve the efficiency of any healthcare system. Therefore, in this paper, the weekly OR planning and scheduling problem is addressed to minimize the waiting time of elective patients, overutilization and underutilization costs of ORs and the total completion time of surgeries. We take into account the available hours of ORs and the surgeons, legal constraints and job qualification of surgeons, and priority of patients in the model. A real-life example is provided to demonstrate the effectiveness and applicability of the model and is solved using ε-constraint method in GAMS software. Then, data envelopment analysis (DEA) is employed to obtain the best solution among the Pareto solutions obtained by ε-constraint method. Finally, the best Pareto solution is compared to the schedule used in the hospitals. The results indicate the best Pareto solution outperforms the schedule offered by the OR director.
Introduction: The prevalence of Chronic Kidney Disease (CKD) in Iran amounts to 15.14%, which is higher than the global average. Given the substantial cost of this disease, health insurance companies ...need evidence of the cost-effectiveness of screening for the disease in adults at risk so that they can control the prevalence of the disease and the associated incremental medical costs by implementing a nationwide screening. Aim: To explore the cost-effectiveness of screening for CKD among adults as compared with having a non-intervention strategy. Materials and Methods: The study had a cross-sectional design and uses the cost-effectiveness analysis approach to compare the costs and outcomes of screening versus nonscreening CKD. The estimated Glomerular Filtration Rate (GFR) was used for primary screening of the population. For this purpose, blood creatinine was measured; subsequently, urine creatinine and volume were analysed. However, some complementary measures and diagnostic tests were employed for positive cases, including the kidney ultrasonography. Costs and outcomes of the two strategies was calculated using a Markov decision model. This model is designed based on the natural course of CKD and GFR as a five-stage model. Costs of services required for patients were calculated based on Iran Health Insurance Organisation database, and outcome data were extracted in terms of the Quality-Adjusted Life-Year (QALY) index. Using TreeAge software, costs and outcomes were simulated for 1000 patients, and sensitivity analysis was used to test the reliability of the model data. Results: For an adult population, the cost-effectiveness ratio for screening versus non-screening was 277,686,954 Rials per QALY, which was the effective cost. The results of one-way sensitivity analysis on the variables of the model shows that the screening strategy can be considered a dominant strategy in different domains. Conclusion: Given the high prevalence of CKD in Iran, early detection of this disease via adult population screening is cost-effective for health insurance companies, and these organisations can control the costs of dialysis and kidney transplantation by reducing the rate of patient transitions from early to the final stages of the disease.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Surgical theater is one of the most expensive hospital sources that a high percentage of hospital admissions are related to it. Therefore, efficient planning and scheduling of the operating rooms ...(ORs) is necessary to improve the efficiency of any healthcare system. Therefore, in this paper, the weekly OR planning and scheduling problem is addressed to minimize the waiting time of elective patients, overutilization and underutilization costs of ORs and the total completion time of surgeries. We take into account the available hours of ORs and the surgeons, legal constraints and job qualification of surgeons, and priority of patients in the model. A real-life example is provided to demonstrate the effectiveness and applicability of the model and is solved using ε-constraint method in GAMS software. Then, data envelopment analysis (DEA) is employed to obtain the best solution among the Pareto solutions obtained by ε-constraint method. Finally, the best Pareto solution is compared to the schedule used in the hospitals. The results indicate the best Pareto solution outperforms the schedule offered by the OR director.
•The majority of cases were in the age group of 50–60 years of old.•A total of 2964 cases of COVID-19 were investigated.•The male-to-female ratio was 1.93:1.•A significant effect of age, gender and ...comorbidities on the mortality.•The Case Fatality Rate among understudy cases was 8.06 %.
An outbreak of COVID-19 in Iran has spread throughout the country. Identifying the epidemiological characteristics of this disease will help to make appropriate decisions and thus control the epidemic. The aim of this study was characterization of the epidemiological features of COVID-19 in Iran.
In this retrospective study, data related to the epidemiological characteristics of COVID-19 patients admitted to Baqiyatallah Hospital in Tehran, Iran, from 19 February 2020 to 15 April 2020 have been analyzed and reported. Patient characteristics including age, gender and underlying diseases were investigated. Data were collected through patient records. Sex ratio, Case Fatality Rate (CFR) and daily trend of cases were also determined. A multiple logistic regression analysis was also performed to assess affecting factors on mortality.
From February 19, 2020 to April 15, 2020, 12870 patients referred to the hospital emergency department, of which 2968 were hospitalized with COVID-19 diagnosis. The majority of cases were in the age group of 50 to 60 years of old. The male-to-female ratio was 1.93:1. A total of 239 deaths occurred among all cases for an overall CFR of 1.85% based on the total number of patients (both outpatient and inpatient) and 8.06% among hospitalized patients. Out of all patients 10.89% had comorbidity. Diabetes, chronic respiratory diseases, hypertension, cardiovascular diseases, chronic Kidney diseases and cancer were the most common comorbidities with 3.81, 2.02 , 1.99 , 1.25, 0.60 and 0.57 %, respectively. Male gender (OR=1.45, 95% CI: 1.08-1.96), older age (OR=1.05, 95% CI: 1.04-1.06) and having underlying diseases (OR=1.53, 95% CI: 1.04-2.24) were significantly associated with mortality.
The results of this study showed that Male gender, older age and having comorbidities were significantly associated with the risk of death among COVID-19 patients. It is important to pay special attention to male elderly patients with underlying diseases.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Solar thermal receivers are designed to absorb as much sunlight as possible (e.g., to increase energy inputs) while minimising heat losses and parasitic pumping energy requirements (e.g., to reduce ...energy losses). The field of direct absorption solar collectors has devised numerous elegant solutions for increasing energy inputs. Mitigating the energy losses, however, represents the other—generally overlooked—factor. To address this research gap, this study investigates the impact of nanofluids, superhydrophobic walls, an anti-reflective coating, and a transparent selective on the thermal efficiency of a microchannel-based solar receiver. The proposed modifications were ranked by their impact on the overall collector efficiency. It was found that compared to a pure water reference case, using a nanofluid working fluid provides the biggest reduction in optical losses (validating the literature's focus on this aspect). However, a micro-patterned surface achieved nearly the same improvement in optical efficiency. Adding a nanofluid, an anti-reflective cover, and a superhydrophobic surface (in concert) can boost the efficiency by ∼7% (compared to the reference case). Overall, this study provides a systematic approach to investigating features to mitigate energy loss mechanisms in direct absorption solar collectors via detailed component-level experimental testing and collector-level theoretical analysis.
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•First principles investigation of the losses in direct absorption solar collectors (DASCs).•Methods for loss mitigation in DASCs are under-developed.•Testing of proposed optical, pumping power, and pressure drop loss mitigation features.•Predicted the effect of each individual modification and their combinations.•All 3 give a ∼7 % boost in thermal efficiency at (@ 300 K) and ∼12 % (@ 673 K).
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
► A continuum model is developed for determining the thermal conductivity of CNT. ► The thermal conductivity of CNTs is a function of temperature and chirality. ► The thermal conductivity of CNT ...(10,10) at 300K is predicted as 9750W/mK. ► The phonon mean free path and the thermal conductivity increase with chiral number.
In this paper, a continuum model is presented to investigate the thermal properties of carbon nanotubes (CNTs). The proposed model considers each carbon–carbon (C–C) bond in CNT as a continuum solid element. The thermal properties of the CNTs can be calculated simply by computing the thermal properties of these solid elements. Considering a thermal resistance for each continuum solid element (C–C bond), equivalent thermal resistance of CNTs can be obtained which is used to determine the thermal conductivity of CNT. In order to find the thermal properties of C–C bond, Debye model has been utilized to calculate the specific heat capacity and thermal conductivity. Then, extended calculations have been carried out to study the thermal conductivity of armchair nanotube (10,10) and its variations with temperature.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
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