Low Unit Research Articles

Centralized and Distributed Optimization for Vehicle-to-Grid Applications in Frequency Regulation

This paper proposes centralized and distributed optimization models for V2G applications to provide frequency regulation in power systems and the electricity market. Battery degradation and dynamic EV usages such as EV driving period, driving distance, and multiple charging/discharging locations are modeled. The centralized V2G problem is formulated into the linear programming (LP) model by introducing two sets of slack variables. However, the centralized model encounters limitations such as privacy concerns, high complexity, and central failure issues. To overcome these limitations, the distributed optimal V2G model is developed by decomposing the centralized model into subproblems using the augmented Lagrangian relaxation (ALR) method. The alternating direction method of multipliers (ADMM) is used to solve the distributed V2G model iteratively. The proposed models are evaluated using real data from the Independent Electricity System Operator (IESO) Ontario, Canada. Simulation results show that the proposed models can aggregate EVs for frequency regulation; meanwhile, the EV owners can obtain monetary rewards. The simulation also shows that including battery degradation and dynamic EV usage increases the model accuracy. By using the proposed approaches, the high cost and the low efficiency power generation units for frequency regulation can be compensated or partially replaced by EVs, which will reduce the generation cost and greenhouse gas emissions.

The influence of fly ash and foam contents on the properties of lightweight foamed concrete

Due to rapid industrialization and modernization, a large number of both fly ash (FA) and ground granulated blast furnace slag (GGBFS), both by-products from thermal power plants and steel factories, are increasing day by day. Thus, recycling these industrial wastes to produce lightweight foamed concrete (LFC) was investigated in this study. Eight LFC mixtures were designed with different FA content and foam content to investigate their effect on the properties of LFC. Test results indicate that both FA and foam contents had a significant influence on the properties of LFC. The quality of LFC decreased with increasing foam content while the presence of FA improved its properties. The properties of LFC and its dry unit weight had a close relationship, and the correlation between them was described by linear regression. For example, high foam content resulted in more void volumes inside the LFC thus reducing its properties. Meanwhile, the presence of FA minimized the void volume and enhanced the LFC’s properties. All LFCs in this investigation showed good quality, which were classified as grade M3.5-12.5 based on TCVN 9029:2017, which means they can be used as unburnt bricks with significantly low unit weight and thermal conductivity.

Patient outcomes in an Australian low secure forensic psychiatric rehabilitation inpatient unit: a 10-year retrospective study

The aim of this study is to investigate the background and discharge outcomes of the forensic patient population rehabilitated through a low secure forensic psychiatric rehabilitation inpatient unit. Currently within Australia and internationally there is a scarcity of research completed within this setting. A quantitative methodology was selected coupled with descriptive statistics to investigate a total of 23 patients and analyse their demographics, historical information, length of stay and post-discharge outcomes including readmission and breach of forensic orders. This study provides insights into this unique patient group and further clarifies their psychiatric treatment and biopsychosocial needs. A significant variance was found within patient length of stay throughout each stage of the forensic system. Low rates of readmissions and breaches of forensic orders were found. Additional research is needed in this low secure psychiatric rehabilitation setting to clarify the forensic pathways of care and needs amongst this cohort.

Audit Cycle on Medical Reviews of Seclusion in Medium and Low Secure Learning Disability Units

AimsSeclusion is defined as “the supervised confinement and isolation of a patient, away from other patients, in an area from which the patient is prevented from leaving, where it is of immediate necessity for the purpose of the containment of severe behavioural disturbance which is likely to cause harm to others”. Patients in seclusion require reviews at the frequency set out in the Mersey Care NHS Foundation Trust policy, “The use of seclusion and long-term segregation” (SD28). This is based on the requirements set out in the Chapter 26 of the Mental Health Act 1983 Code of Practice (2015).This audit will look at whether medical reviews for secluded patients in the secure learning disability wards meet with the expectations set out in the Trust Policy. In doing so, the audit will establish whether medical reviews of seclusion meet and uphold the guiding principles of the Mental Health Act Code of Practice as highlighted in Chapter 26.110.MethodsRetrospective audit that collected data from inpatients on secure learning disability wards in Mersey Care. After reviewing data, we actioned plans which involved educating colleagues working in secure services. This was re audited after three months. One month of seclusion reviews was audited in each cycle, which equated to 39 reviews in the first cycle and 100 reviews in the second.ResultsThe re-audit data showed an improvement in most parameters.Re-audit showed that 66% (34%) of the seclusion reviews had an initial medical review within the first hour. The on call consultant was informed in 60% (50%) of the situations and 4 hourly reviews took place in 66% (50%) of scenarios. All MDT reviews took place within 24 hours, Responsible Clinician was present in 100% (67%) of reviews.34% (33%) of MDT reviews had only 2 MDT members.There was 100% compliance with reviewing physical health in both audits. 100% (90%) of the reviews commented on mental health, 72% (20%) commented on medications used, 51% (39%) of reviews commented on level of observations and 89% (48%) included risk assessment. 95% (92%) of reviews assessed need for continuing seclusion. 84% (59%) of reviews commented on reducing restriction in seclusion.ConclusionThis audit cycle has focused on the quality of medical reviews and not just the frequency. The improvement in practice will strengthen the safeguard provided by these reviews.

Service-User Led Recommendations on Improving Medium to Low Secure Unit Transfer Experiences in East London During COVID-19; a Quality Improvement Project

AimsForensic service-users (SU) are often transferred between units at short notice, with little information about their new ward and unaddressed concerns. The findings of our first Plan, Do, Study, Act (PDSA) quality improvement project exploring SU's transfer experiences from medium to low secure units during COVID-19 in East London. Whilst unsettling, it may also impact therapeutic progress due to difficulties in developing new relationships with clinicians and ward residents. Our second PDSA cycle explores SU concerns and identifies improvement recommendations.MethodsFive SUs consented to take part in the experience-based co-design approach. Remote semi-structured interviews explored experiences and suggestions for improvement. Audio transcriptions were thematically analysed to assess information provision, transfer expectations, new ward perceptions, available support and overall reflections.ResultsRecipients of a tour prior to moving felt most informed about the transfer and reported not requiring further information. Without the tour, some SUs were unaware of the name or type of their future ward. Therefore, SUs recommended everyone should have a tour prior to transfer, or where not possible a video tour. Two weeks was felt to be the ideal amount of notice prior to transfer and in the absence of this, weekly updates during ward round. Being able to talk to an SU who had recently moved to the new unit would be ideal, or in lieu of this a pre-recorded question and answer (Q&A) video.SUs were interested in the new ward policy regarding leave and mobile phone criteria. A recurring issue involved SUs being promised unescorted leave on the new ward, but this not taking place. Importance was also placed on the family being updated during the transfer and moving with a preferred staff member. Many SUs felt the process was smooth yet held concerns about forming new friendships. They felt their psychologist, primary nurse or ward manager were easiest to approach with concerns. On the transfer day, SUs benefitted from the encouragement and congratulations from the old team, however cited feeling rushed when moving.ConclusionImplementing a pre-recorded tour with unit facility highlights and a recent SU transfer Q&A video would improve the transfer experience. Having clear policies regarding leave and mobile phone criteria prior to moving improves clarity. Our approach to include SUs in the transfer meeting with both the new and old wards ensures transparent expectations. We continue to monitor the success of these interventions on transfer experience through further PDSA cycles.

An Audit Cycle Highlighting the Rate of Chlamydia Screening in a Forensic Child and Adolescent Mental Health Unit in Birmingham

AimsChlamydia, a sexually transmitted bacterial infection caused by Chlamydia Trachomatis can result in long-term complications for affected individuals. The National chlamydia screening programme recommends screening at-risk young persons, however for the vulnerable patients at the Forensic Child and Adolescent Mental Health Service (FCAMHS), there has been no audit to determine the completion rate. This audit aim to (1) Determine the demographics of young persons on admission (2) To determine the rate of chlamydia screening as well as the percentage of patients who qualified for a Chlamydia screening(3) To determine the rate of documentation for completed tests.MethodsThis was a retrospective study. The medical electronic records of patients who met the inclusion criteria was searched. All the three mixed-sex adolescent forensic wards (2 medium secure units and one low secure unit) at FCAMHS Ardenleigh, Birmingham were sampled.All patients that were on admission aged above 15 years of age were recruited.A total sample size of 19 was obtained for the initial audit and 12 for the re-audit.Data collectionData were collected by the author for the initial-audit and re-audit by searching the clinical progress notes, the investigation results and the physical health rethink forms. An excel software was used for analysis.ResultsDemographicsThere were 11 males (57.9%) and 8 females (42.1%) in the initial auditIn the re-audit, there were 7 males (58.3) and 5 females (41.7). Some of the patients were still on admission at the time of the re-audit, hence the percentages were calculated differently. The mean age and average length of admission was also calculated.Chlamydia screeningIn the initial audit, the percentage of patients tested for Chlamydia was 11.5%, even though 36.8% of patients met the criteria for Chlamydia screening. In the re-audit, 25.0% were tested, and 41.7% met the criteria for Chlamydia screening.Physical health (Rethink) formsThe physical health form was completed for majority of patients 73.7% in the initial audit although, this was not compatible with screening rates. Before the re-audit was concluded, the physical health forms were no longer in use.ConclusionThe audit highlighted an overall improvement in the rate of screening following recommendations from initial audit. The inclusion of Chlamydia screening in admission processes could be useful in improving sexual health.

A Low Cost Electrosurgery Unit (ESU) Design with Monopolar and Bipolar Methods

Surgery using a conventional scalpel causes the patient to lose a lot of blood; this needs to be avoided. The purpose of this research is to make a replacement for the conventional scalpel using a device that utilizes high frequency with a duty cycle setting that is centered at one point. The design of the device is equipped with monopolar and bipolar pulse selection with an increased frequency at 400 kHz, where the duty cycle of bipolar mode can be set to 100% on and the coagulation duty cycle is 6% on and 94% off. The power output of the module was tested using an ESU Analyzer, while cutting the bipolar forceps used soap and meat media. The power inverter circuit was set with the module impedance values ​​of 300Ω, 400Ω, and 500Ω. Power settings were set at high, medium, and low with 2 pulse cutting and coagulation modes. The average power resulted in the lowest power of 32.3Watt and the highest power cutting mode of 58.3Watt. Meanwhile, in the coagulation mode of the lowest power of 3Watt and the highest power of 3Watt, the impedance setting is 500Ω. The module can output power linearly according to settings and can cut media well. Furthermore, the development of making Electrosurgery design in this study is expected to facilitate the surgical process during the surgical procedures.

Effects of Crumb Rubber on the Shear Strength of Sand: An Experimental Study

The application of waste rubber tires for ground improvement helps to improve the environment by recycling and reusing it as admixtures. This research aims to investigate the shear strength parameters of rubber-sand mixtures. By using crumb rubber with a constant size (425μm), the sand is replaced by different percentages (0, 2.5, 5.0, 7.5, and 10%) of crumb rubber by weight. A direct shear box test is used to determine the shear strength parameters of rubber-sand mixtures with two different controlled densities. The samples were loaded with normal stresses of 20, 40 and 80kPa and were sheared at a rate of 1mm/min. Although, this experiment discovered that crumb rubbers improve the shear strength parameters in loose sand, however, a reduction in shear strength parameters was found in dense sand. Moreover, it was observed that the inclusion of crumb rubbers into sand greatly improve the strain energy of both loose and dense sand. Likewise, rubber has a low unit weight which makes it suitable for lightweight backfill materials. The surface properties of rubber should be further studied to understand the contribution of shear strength in the rubber-sand mixture.

Investigating the production of platelet lysate obtained from low volume Cord Blood Units: Focus on growth factor content and regenerative potential

BackgroundThe regenerative potential of platelet lysate (PL) and platelet gel (PG) is mediated by the release of platelets (PLTs) growth factors. The aim of this study was the evaluation of the PL production utilizing low volume single Cord Blood Units (CBUs) and the comparison of the biomolecule content between PLs obtained from intermediate and high volume CBUs. MethodsCBUs (n = 90) with volumes greater than 50 ml and initial platelet count > 150 × 109/L were used. CBUs were classified into the following groups: group A (50–80 ml), group B (81–110 ml) and group C (111–150 ml). The CBUs were centrifuged twice for the production of the platelet concentrate (PC), which was stored at − 80 °C for at least 48 h. Then, rapidly thawed and the biomolecule content was determined using commercial ELISA kits. The regenerative potential of PLs was evaluated using the scratch wound and in vitro angiogenesis assay. ResultsCBPL was produced from low volume single CBUs and contained 3.4 ± 0.3 ×109 PLTs. PL obtained from intermediate and high volume CBUs consisted of 10.2 ± 0.3 and 16.1 ± 0.4 × 109 PLTs. All PL groups were characterized by high biomolecule content. Gap closure was observed within 72 h after the wound assay initiation and the capillary tubes were formed in all study groups. ConclusionThis study provided significant evidence regarding the utilization of the low volume CBUs for the production of CB derivatives, thus can serve as healing mediators in regenerative medicine approaches.

Unity Makes Strength: Constructing Polymeric Catalyst for Selective Synthesis of CO 2 /Epoxide Copolymer

Unity Makes Strength: Constructing Polymeric Catalyst for Selective Synthesis of CO ₂ /Epoxide Copolymer

Risk factors for recollapse of new vertebral compression fractures after percutaneous kyphoplasty in geriatric patients: establishment of a nomogram

BackgroundThe main objective of this study was to investigate the risk factors for recollapse of new vertebral compression fractures (NVCFs) after percutaneous kyphoplasty (PKP) treatment for osteoporotic vertebral compression fracture (OVCF) and to construct a new nomogram model.MethodsWe retrospectively analysed single-level OVCFs from January 2017 to June 2020, randomizing patients to a training set and a testing set. In the training set, independent risk factors for NVCFs in OVCF patients treated with PKP were obtained by univariate and multivariate regression analyses. These risk factors were then used as the basis for constructing a nomogram model. Finally, internal validation of the built model was performed in the testing set using the consistency index (C-index), receiver operating characteristic (ROC) curves, calibration curves and decision curve analysis (DCA).ResultsIn total, 371 patients were included in this study. NVCFs occurred in 21.7% of the training set patients, and multivariate regression analysis showed that a low Hounsfield unit (HU) value, cement leakage, and thoracolumbar (TL) junction fracture were independent risk factors for NVCF after PKP. The C-index was 0.81 (95% CI: 0.74–0.81), and the validation showed that the predicted values of the established model were in good agreement with the actual values.ConclusionsIn this study, three independent risk factors were obtained by regression analysis. A nomogram model was constructed to guide clinical work and to make clinical decisions relatively accurately to prevent the occurrence of vertebral recollapse fractures.

Simulating Socio-Technical Transitions of Photovoltaics Using Empirically Based Hybrid Simulation-Optimization Approach

Energy transitions as socio-technical processes involves interactions among different actors such as households, firms, and government, thus requiring an integrated approach to explore the transition’s dynamics. The present study aims to simulate the socio-technical transitions of photovoltaics (PV) in Indonesia using an empirically based hybrid simulation-optimization model. The model involves households’ decision-making, PV supply chain, and government interventions. The hybrid simulation-optimization model consists of integer linear programming to optimize PV’s supply chain configuration which was embedded within agent-based modeling and simulation (ABM). The empirical data involving 413 households from 34 provinces in Indonesia was acquired from a survey that was specifically designed based on the Unified Theory of Acceptance and Use of Technology 2 (UTAUT2) to specify and parameterize the model. Export tariff regulation, incentives for PV investment, environmental campaigns, and the combinations of those interventions were evaluated. The findings demonstrate that all of the interventions increase the intention toward PV, but the intention is not necessarily translated into adoption due to either financial or facility constraints. The findings highlight the necessity to include both demand and supply aspects endogenously in the transition model. The export tariffs combined with the incentives, followed by the export tariffs combined with the campaigns, is found to be preferable due to low supply chain unit cost and high reduction of greenhouse gas. Managerial implications and future research are discussed.

The site characterization of central jakarta soft soil using CPTu and laboratory test

Construction activities has been named as one of the contributing factors to Jakarta’s alarming rate of land subsidence, which ranges between 1 to 15 cm annually, and up to 28 cm in some locations. This problem is commonly known as settlement, and the affected soft soil is usually attributed to under-consolidating soil (UC). In regards to that matter, this study aims to characterize the soft soil layer in Central Jakarta using the Cone Penetration Test with pore pressure measurement (CPTu) and laboratory assessment. In addition, Undrained Shear Strength () and Pore Pressure Ratio (and ) methods were used to estimate the over-consolidation Ratio (OCR) values. The data collected from 94 boreholes and 30 CPTu showed the soft soil layers in Central Jakarta, which was dominated by high-plasticity silty clay (CH) and clayey silt (MH). The layers are detected between the depth of 0 – 25 m and are characterized by high natural moisture content, void ratio, liquidity index, and compression index values. Within this layer of under consolidated soils, the indication of relatively low dry unit weight was also present. Furthermore, the laboratory tests showed several correlations related to under-consolidating soil, i.e. void ratio to in-situ effective stress, void ratio to compression index, and compression index to natural moisture content. The CPTu test interpretations returned a number of under-consolidation soil layer samples in Central Jakarta. Moreover, the result also indicates the presence of under-consolidating properties, as well as normally consolidated and lightly over-consolidated.

Probabilistic Framework Allocation on Underwater Vehicular Systems Using Hydrophone Sensor Networks

This article emphasis the importance of constructing an underwater vehicle monitoring system to solve various issues that are related to deep sea explorations. For solving the issues, conventional methods are not implemented, whereas a new underwater vehicle is introduced which acts as a sensing device and monitors the ambient noise in the system. However, the fundamentals of creating underwater vehicles have been considered from conventional systems and the new formulations are generated. This innovative sensing device will function based on the energy produced by the solar cells which will operate for a short period of time under the water where low parametric units are installed. In addition, the energy consumed for operating a particular unit is much lesser and this results in achieving high reliability using a probabilistic path finding algorithm. Further, two different application segments have been solved using the proposed formulations including the depth of monitoring the ocean. To validate the efficiency of the proposed method, comparisons have been made with existing methods in terms of navigation output units, rate of decomposition for solar cells, reliability rate, and directivity where the proposed method proves to be more efficient for an average percentile of 64%.

Dye-Sensitized Solar Cells (DSSCS) Based on a Natural Dye (<i>Mangifera indica</i>): A Mini Review

The long-term viability of human civilization is heavily reliant on a sustainable energy supply, and fossil fuels have long been the most sustainable source of energy. However, since fossil fuels are a non - renewable energy source, their depletion is unavoidable and inevitable in this century. Renewable energy, notably solar energy (SE), has gotten a lot of attention as a solution to this problem because it transforms SE through technology into electrical power (EP) with no environmental impact. For its inherent low unit cost and simplicity of production, organic-solar cells (OSCs) have recently been the topic of investigation for both home and commercial uses. OSCs also have a weight and flexibility benefit over standard silicon-based crystalline solar cells (CSCs). Research has suggested that dye sensitized solar cells (DSSCs) are the most effective and simple to implement of all the OSCs. In this mini review, we survey the existing DSSCs literature and attempts made to improve its performance based on mangifera indica natural dye, an eco-friendly, cost-effective, easy to extract, source of natural dye with high conversion efficiency.

Structural and luminescence characterization of europium-doped niobium germanate glasses and glass-ceramics: Novel insights from 93Nb solid-state NMR spectroscopy

A thorough understanding of network former roles in optical glasses and glass-ceramics, as well as structural environments of luminescent rare-earth atoms, is paramount to assessing their suitability and effectiveness as components for fully-optical integrated devices. The present contribution sheds light on the overall poorly understood structural role of Nb2O5 in oxide glasses and offers a rationale for the luminescence changes concomitant to the heat-treatment induced glass-to-crystal transition in niobium germanate glasses. To this end, results from 93Nb nuclear magnetic resonance (NMR), Raman, and Eu3+ ion based luminescence spectroscopies as well as 3D micromanufacturing are reported for glasses and glass-ceramics in system (89.9-x)GeO2-xNb2O5-10K2O-0.1Eu2O3. Thanks to very-fast 93Nb magic-angle spinning (MAS) and a novel excitation scheme for Triple-quantum (TQ)MAS solid-state NMR spectroscopy distinct Nb(OGe)6-y(ONb)y species were identified for the first time: at low Nb concentrations structural units with rather low y-values are formed, reaching down to isolated Nb(OGe)6 units – next to units bearing non-bridging oxygen atoms; at intermediate Nb contents and beyond, structural units with increasingly higher y-values up to Nb(ONb)6 are found, resembling the local environments found in crystalline Nb2O5. After the glass-to-crystal transition the Nb local environment maintains a high degree of disorder while some residual glass remains. Moreover, photoluminescence spectroscopy of the europium probes suggests the rare-earth ions are preferentially incorporated into high y-value Nb(OGe)6-y(ONb)y polyhedra based on spectral features such as the phonon sideband, the 5D0 → 7F2/7F1 ratio, and split 4f bands. Finally, femtosecond laser microfabrication of waveguides was successful in the presented europium-doped niobium germanate glasses, making them promising candidates for further studies as photonic devices.

Mathematical description of the grain cleaning process on the experimental facility

Machines with pneumatic systems are used to clean grain from light impurities and dust. Modern grain cleaning machines for preliminary cleaning from light impurities and dust with a pneumatic system do not fully meet the increasing requirements of modern agricultural production in terms of their performance. The article presents the principle of operation and a mathematical description that allows you to determine the main parameters of the installation. In this work, an analytical research method was used based on the analysis of differential equations describing the processes of cleaning grain from light impurities and dust. To develop a mathematical model, the method of constructing Lagrange mathematical models was applied. On the basis of this model, a number of equations were constructed that characterize: the transition of the potential energy of the grain mass into the kinetic energy of the grain flow; dynamic equation of the equilibrium fall of the grain flow; the volume flow rate of the air flow in the intergranular space, as well as an equation that makes it possible to determine the pressure loss in the air flow passing through the blinds and the average speed of the grains falling. Taking into account the above equations, a mathematical model is built in the form of a system of equations. This mathematical model makes it possible to determine the main design parameters of the new installation: the geometric dimensions of the working area, as well as energy costs for the grain cleaning process. The introduction of the developed installation at the receiving points of the elevators makes it possible to increase the efficiency of grain cleaning from light impurities and dust at low unit costs.

Frequency of Grades of Meconium-Stained Liquor and Compare the Frequency of Fetal Outcome according to Grades of Meconium-Stained Liquor

Objective: To determine the different grades of meconium-stained liquor and association of fetal outcome (still birth, poor Apgar score, NICU admissions) among meconium-stained liquor patients according to their grades. Subject and Methods: This prospective case series study was conducted at the department of obstetrics and Gynaecology, civil Hospital Karachi, for 6 months from April 2019 to September 2019. After per vaginal examination meconium-stained amniotic liquor and grades of meconium-stained liquor were confirmed and these patients were monitored by auscultation of fetal heart sounds by pinard stethoscope and cardiotocography performed and when patients delivered, the frequency of fetal outcome according to grades noted and was documented on pre-designed proforma. Results: A total of 150 patient women were studied, their average age was 28.62±4.19 years and mean gestational age was 38.38+1.00 weeks. There 56% multiparous women. Of all meconium-stained liquor, grade II was commonest 40%, grade I 30% and grade III 30%. Still birth was 2.0%, poor Apgar score was 24.7% and rate of NICU admission was 28.0%. Maternal age, parity and gestational age effects were statistically significant on grade of liquor (p-<0.05). Conclusion: Meconium-stained liquor grade II was observed to be high. The adverse fetal outcomes in terms of still birth, low Apgar score and neonatal intensive care unit admission were observed to the significancy associated with meconium-stained liquor grades II and III. Meconium-stained amniotic fluid as a serious problem so early decision should be taken to improve the fetal outcome. Keywords: Meconium-stained amniotic fluid, still birth, poor Apgar score

High-altitude is associated with better short-term survival in critically ill COVID-19 patients admitted to the ICU.

Multiple studies have attempted to elucidate the relationship between chronic hypoxia and SARS-CoV-2 infection. It seems that high-altitude is associated with lower COVID-19 related mortality and incidence rates; nevertheless, all the data came from observational studies, being this the first one looking into prospectively collected clinical data from severely ill patients residing at two significantly different altitudes. A prospective cohort, a two-center study among COVID-19 confirmed adult patients admitted to a low (sea level) and high-altitude (2,850 m) ICU unit in Ecuador was conducted. Two hundred and thirty confirmed patients were enrolled from March 15th to July 15th, 2020. From 230 patients, 149 were men (64.8%) and 81 women (35.2%). The median age of all the patients was 60 years, and at least 105 (45.7%) of patients had at least one underlying comorbidity, including hypertension (33.5%), diabetes (16.5%), and chronic kidney failure (5.7%). The APACHE II scale (Score that estimates ICU mortality) at 72 hours was especially higher in the low altitude group with a median of 18 points (IQR: 9.5-24.0), compared to 9 points (IQR: 5.0-22.0) obtained in the high-altitude group. There is evidence of a difference in survival in favor of the high-altitude group (p = 0.006), the median survival being 39 days, compared to 21 days in the low altitude group. There has been a substantial improvement in survival amongst people admitted to the high-altitude ICU. Residing at high-altitudes was associated with improved survival, especially among patients with no comorbidities. COVID-19 patients admitted to the high-altitude ICU unit have improved severity-of-disease classification system scores at 72 hours.

How Short-Term Rentals are Changing the Neighborhood

This paper examines how short-term rentals are changing living conditions and the composition of the population in affected parts of a town. First, to analyze the relation between quality, distance, and rents, we develop a spatial monocentric city model with varying housing quality levels. Second, for 200 m grids in the city of Berlin (Germany) in 2019, we show that the proportion of low and medium quality residential units correlates positively near the city center with the probability of Airbnb listings and the number of these listings, but negatively in the suburbs. Third, applying fixed effect and IV strategies, we investigate the impact of Airbnb listings on living conditions and the composition of the population in the almost 450 planning areas of Berlin in the years 2016–2019. We show that Airbnb offers increase the number of residents with long periods of residence and reduce the number of residents in low-quality residential environments, but we do not find above-average effects on socially weak groups. JEL Classification: R21, R31, Z32