Sierpinski carpet fractal monopole antenna for ultra-wideband applications

Microstrip antenna is broadly used in the modern communication system due to its significant features such as light weight, inexpensive, low profile, and ease of integration with radio frequency devices. The fractal shape is applied in antenna geometry to obtain the ultra-wideband antennas. In this paper, the sierpinski carpet fractal monopole antenna (SCFMA) is developed for base case, first iteration and second iteration to obtain the wideband based on its space filling and self-similar characteristics. The dimension of the monopole patch size is optimized to minimize the overall dimension of the fractal antenna. Moreover, the optimized planar structure is proposed using the microstrip line feed. The monopole antenna is mounted on the FR4 substrate with the thickness of 1.6 mm with loss tangent of 0.02 and relative permittivity of 4.4. The performance of this SCFMA is analyzed in terms of area, bandwidth, return loss, voltage standing wave ratio, radiation pattern and gain. The proposed fractal antenna achieves three different bandwidth ranges such as 2.6-4.0 GHz, 2.5-4.3 GHz and 2.4-4.4 GHz for base case, first and second iteration respectively. The proposed SCFMA is compared with existing fractal antennas to prove the efficiency of the SCFMA design. The area of the SCFMA is 25×20 mm², which is less when compared to the existing fractal antennas.

Health and Economic Consequences of Universal Paid Sick Leave Policies During the COVID-19 Pandemic

Importance: Universal paid sick-leave (PSL) policies have been implemented in jurisdictions to mitigate the spread of SARS-CoV-2. However empirical data regarding health and economic consequences of PSL policies is scarce. Objective: To estimate effects of a universal PSL policy in Ontario, Canada's most populous province. Design: An agent-based model (ABM) to simulate SARS-CoV-2 transmission informed by data from Statistics Canada, health administrative sources, and from the literature. Setting: Ontario from January 1st to May 1st, 2021. Participants: A synthetic population (1 million) with occupation and household characteristics representative of Ontario residents (14.5 million). Exposure: A base case of existing employer-based PSL alone versus the addition of a 3- or 10-day universal PSL policy to facilitate testing and self-isolation among workers infected with SARS-CoV-2 themselves or because of infected household members. Main Outcome(s) and Measure(s): Number of SARS-CoV-2 infections and COVID-19 hospitalizations, worker productivity, lost wages, and presenteeism (going to a workplace while infected).

Numerical Assessment of Zebra-Stripes-Based Strategies in Buildings Energy Performance: A Case Study under Tropical Climate

Urban growth has increased the risk of over-heating both in the microclimate and inside buildings, affecting thermal comfort and energy efficiency. That is why this research aims to evaluate the energy performance of buildings in terms of thermal comfort (operative temperature (OP) levels, satisfied hours of natural ventilation SHNV, thermal lag), and energy efficiency (roof heat gains and surface temperatures) in an urban area in Panama City, using superficial-heat-dissipation biomimetic strategies. Two case studies, a base case and a proposed case, were evaluated using the Designbuilder software through dynamic simulation. The proposed case is based on a combined biomimetic strategy; the reflective characteristics of the Saharan ant applied as a coating on the roofs through a segmented pattern such as the Zebra’s stripes (one section with coating, and another without). Results showed that the OP decreased from 8 to 10 °C for the entire urban zone throughout the year. A reduction of 3.13% corresponding to 8790 kWh per year was achieved for cooling energy consumption. A difference of 5 °C in external surface temperature was obtained, having a lower temperature in which the biomimetic strategy was applied. Besides, it was evidenced that a contrasted-reflectivity-stripes pitched roof performed better than a fully reflective roof. Thus, the functionality of Zebra stripes, together with the reflective characteristics of the Saharan ant, provide better performance for buildings’ thermal regulation and energy needs for cooling.

Cost-effectiveness of thrombectomy in patients with minor stroke and large vessel occlusion: effect of thrombus location on cost-effectiveness and outcomes

BackgroundTo evaluate the cost-effectiveness of endovascular thrombectomy (EVT) to treat large vessel occlusion (LVO) in patients with acute, minor stroke (National Institute of Health Stroke Scale (NIHSS) <6) and impact of occlusion site.MethodsA Markov decision-analytic model was constructed accounting for both costs and outcomes from a societal perspective. Two different management strategies were evaluated: EVT and medical management. Base case analysis was done for three different sites of occlusion: proximal M1, distal M1 and M2 occlusions. One-way, two-way and probabilistic sensitivity analyses were performed.ResultsBase-case calculation showed EVT to be the dominant strategy in 65-year-old patients with proximal M1 occlusion and NIHSS <6, with lower cost (US$37 229 per patient) and higher effectiveness (1.47 quality-adjusted life years (QALYs)), equivalent to 537 days in perfect health or 603 days in modified Rankin score (mRS) 0–2 health state. EVT is the cost-effective strategy in 92.7% of iterations for patients with proximal M1 occlusion using a willingness-to-pay threshold of US$100 000/QALY. EVT was cost-effective if it had better outcomes in 2%–3% more patients than intravenous thrombolysis (IVT) in absolute numbers (base case difference −16%). EVT was cost-effective when the proportion of M2 occlusions was less than 37.1%.ConclusionsEVT is cost-effective in patients with minor stroke and LVO in the long term (lifetime horizon), considering the poor outcomes and significant disability associated with non-reperfusion. Our study emphasizes the need for caution in interpreting previous observational studies which concluded similar results in EVT versus medical management in patients with minor stroke due to a high proportion of patients with M2 occlusions in the two strategies.

Cost-Effectiveness of Pembrolizumab Plus Chemotherapy Versus Pembrolizumab Monotherapy in Metastatic Non-Squamous and Squamous NSCLC Patients With PD-L1 Expression ≥ 50%

Objective To compare the cost-effectiveness of the combination of pembrolizumab and chemotherapy (Pembro+Chemo) versus pembrolizumab monotherapy (Pembro) as the first-line treatment for metastatic non-squamous and squamous non-small-cell lung cancer (NSCLC) with PD-L1expression ≥50%, respectively, from a US health care perspective.Material and Methods A comprehensive Makrov model were designed to compare the health costs and outcomes associated with first-line Pembro+Chemo and first-line Pembro over a 20-years time horizon. Health states consisted of three main states: progression-free survival (PFS), progressive disease (PD) and death, among which the PFS health state was divided into two substates: PFS while receiving first-line therapy and PFS with discontinued first-line therapy. Two scenario analyses were performed to explore satisfactory long-term survival modeling.Results In base case analysis, for non-squamous NSCLC patients, Pembro+Chemo was associated with a significantly longer life expectancy [3.24 vs 2.16 quality-adjusted life-years (QALYs)] and a substantially greater healthcare cost ($341,237 vs $159,055) compared with Pembro, resulting in an ICER of $169,335/QALY; for squamous NSCLC patients, Pembro+Chemo was associated with a slightly extended life expectancy of 0.22 QALYs and a marginal incremental cost of $3,449 compared with Pembro, resulting in an ICER of $15,613/QALY. Our results were particularly sensitive to parameters that determine QALYs. The first scenario analysis yielded lower ICERs than our base case results. The second scenario analysis founded Pembro+Chemo was dominated by Pembro.Conclusion For metastatic non-squamous NSCLC patients with PD-L1 expression ≥50%, first-line Pembro+Chemo was not cost-effective when compared with first-line Pembro. In contrast, for the squamous NSCLC patient population, our results supported the first-line Pembro+Chemo as a cost-effective treatment. Although there are multiple approaches that are used for extrapolating long-term survival, the optimal method has yet to be determined.

Chamber investigation of the formation and transformation of secondary organic aerosol in mixtures of biogenic and anthropogenic volatile organic compounds

A comprehensive investigation of the photochemical secondary organic aerosol (SOA) formation and transformation in mixtures of anthropogenic (o-cresol) and biogenic (α-pinene and isoprene) volatile organic compound (VOC) precursors in the presence of NOx and inorganic seed particles was conducted. Initial iso-reactivity was used to enable direct comparison across systems, adjusting the initial reactivity of the systems towards the assumed dominant oxidant (OH). Comparing experiments conducted in single precursor systems at various initial reactivity levels (referenced to a nominal base case VOC reactivity) and their binary and ternary mixtures, we show that the molecular interactions from the mixing of the precursors can be investigated and discuss limitations in their interpretation. The observed average SOA yields in descending order were found for the α-pinene (32 ± 7 %), α-pinene/o-cresol (28 ± 9 %), α-pinene at ½ initial reactivity (21 ± 5 %), α-pinene/isoprene (16 ± 1 %), α-pinene at ⅓ initial reactivity (15 ± 4 %), o-cresol (13 ± 3 %), α-pinene/o-cresol/isoprene (11 ± 4%), o-cresol at ½ initial reactivity (11 ± 3 %), o-cresol/isoprene (6 ± 2 %) and isoprene systems (0 ± 0 %). We find a clear suppression of the SOA yield from α-pinene when it is mixed with isoprene, whilst the addition of isoprene to o-cresol may enhance the mixture’s SOA formation potential, however, the difference was too small to be unequivocal. The α-pinene/o-cresol system yield appeared to be increased compared to that calculated based on the additivity, whilst in the α-pinene/o-cresol/isoprene system the measured and predicted yield were comparable. However, in mixtures where more than one precursor contributes to the SOA mass it is unclear whether changes in the SOA formation potential are attributable to physical or chemical interactions, since the reference basis for the comparison is complex. Online and offline chemical composition and SOA particle volatility, water uptake and “phase” behaviour measurements that were used to interpret the SOA formation and behaviour are introduced and detailed elsewhere.

Exergy Analysis of Alternative Configurations of Biomass-Based Light Olefin Production System with a Combined-Cycle Scheme via Methanol Intermediate

Thermodynamic performance of three conceptual systems for biomass-derived olefin production with electricity cogeneration was studied and compared via exergy analysis at the levels of system, subsystem and operation unit. The base case was composed of the subsystems of gasification, raw fuel gas adjustment, methanol/light olefin synthesis and steam & power generation, etc. The power case and fuel case were designed as the combustion of a fraction of gasification gas to increase power generation and the recycle of a fraction of synthesis tail gas to increase olefin production, respectively. It was found that the subsystems of gasification and steam & power generation contribute ca. 80% of overall exergy destruction for each case, of which gasifier and combustor are the main exergy destruction sources, due to the corresponding chemical exergy degrading of biomass and fuel gas. The low efficiency of 33.1% for the power case could be attributed to the significant irreversibility of the combustor, economizer, and condenser in the combined-cycle subsystem. The effect of the tail gas recycle ratio, moisture content of feedstock, and biomass type was also investigated to enhance system exergy performance, which could be achieved by high recycle ratio, using dry biomass and the feedstock with high carbon content. High system efficiency of 38.9% was obtained when oil palm shell was used, which was 31.7% for rice husk due to its low carbon content.

Effects of Evaporative Emissions Control Measurements on Ozone Concentrations in Brazil

In this work, the possible benefits obtained due to the implementation of evaporative emissions control measures, originating from vehicle fueling processes, on ozone concentrations are verified. The measures studied are: (1) control at the moment when the tank trucks supply the fuel to the gas stations (Stage 1); (2) control at the moment when the vehicles are refueled at the gas stations, through a device installed in the pumps (Stage 2); (3) same as the previous control, but through a device installed in the vehicles (ORVR). The effects of these procedures were analyzed using numerical modeling with the VEIN and WRF/Chem models for a base case in 2018 and different emission scenarios, both in 2018 and 2031. The results obtained for 2018 show that the implementation of Stages 1 and 2 would reduce HCNM emissions by 47.96%, with a consequent reduction of 19.9% in the average concentrations of tropospheric ozone. For 2031, the greatest reductions in ozone concentrations were obtained with the scenario without ORVR, and with Stage 1 and Stage 2 (64.65% reduction in HCNM emissions and 31.93% in ozone), followed by the scenario with ORVR and with Stage 1 and Stage 2 (64.39% reduction in HCNM emissions and 32.98% in ozone concentrations).

Passive Design Strategies for Energy Efficient Buildings in the Arabian Desert

This study aims to assess passive design features through the extensive modifications of building envelopes to affect the energy efficiency of residential buildings in hot arid climates. In support of the aim of this research, the annual electric energy bill of a typical residential building in Sharurah was collected and analyzed. Then, the DesignBuilder simulation program was used to investigate how different modifications of building envelopes could affect the energy consumption of the residential buildings under common scenarios. Varied thermal insulation, different types of glass, shading devices, and green roof were investigated with this perspective. The simulation results show that thermal insulation can significantly reduce annual energy consumption by as high as 23.6%, followed by green roofs. In contrast, shading devices and glazing system types were fewer superiors. The results also indicate that the effective combination of certain strategies can reduce total energy consumption by 35.4% relative to the base case (BC) of this research.

Effects of oligomerization and decomposition on the nanoparticle growth: a model study

The rate at which freshly formed secondary aerosol particles grow is an important factor in determining their climate impacts. The growth rate of atmospheric nanoparticles may be affected by particle-phase oligomerization and decomposition of condensing organic molecules. We used the Model for Oligomerization and Decomposition in Nanoparticle Growth (MODNAG) to investigate the potential atmospheric significance of these effects. This was done by conducting multiple simulations with varying reaction-related parameters (volatilities of the involved compounds and reaction rates) using both artificial and ambient measured gas-phase concentrations of organic vapors to define the condensing vapors. While our study does not aim at providing information on any specific reaction, our results indicate that particle-phase reactions have significant potential to affect the nanoparticle growth. In simulations in which one-third of a volatility basis set bin was allowed to go through particle-phase reactions, the maximum increase in growth rates was 71 % and the decrease 26 % compared to the base case in which no particle-phase reactions were assumed to take place. These results highlight the importance of investigating and increasing our understanding of particle-phase reactions.