Your browser doesn't support javascript.
Show: 20 | 50 | 100
Results 1 - 4 de 4
Filter
1.
IEEE Access ; 2022.
Article in English | Scopus | ID: covidwho-1779060

ABSTRACT

We propose a new concept and architectural design for a double hybrid tailsitter unmanned aerial vehicle with vertical takeoff and landing capability. Basically, it consists of a modified flying wing with a single combustion powertrain set and a multirotor with 2 powertrain sets with electric motors. To this end, we have designed, built, and tested a prototype that spends less energy on vertical taking off and landing and also on horizontal flight, for maximizing flight endurance and distance.With electric propellers fixed at the leading wing edge, the tailsitter has two standard surfaces for elevation control and two vertical stabilizers that are used to give the necessary direction on vertical takeoff and landing. Experiments and results show the versatility of our hybrid tailsitter for operations in a restricted field. We performed several tests starting with the aircraft on the ground in vertical positioning. These tests include executing vertical takeoffs and landing, transitions from vertical to horizontal flight modes and transitions back from horizontal to vertical flight modes, and hovering, which were carried out successfully. Transition fourth and back from combustion to multirotor modes are inherent to some of those flight mode transitions, which have been performed smoothly.We also performed tests (in bench) to estimate the flight endurance. Final autonomous flight adjustments were not performed due to the Covid-19 pandemic caused by SARS-CoV-2. To this end the proposed and currently built prototype has proven to be functional as an effective hybrid UAV system. Author

2.
MEDLINE;
Preprint in English | MEDLINE | ID: ppcovidwho-326588

ABSTRACT

Reports of new-onset diabetes and diabetic ketoacidosis in individuals with COVID-19 have led to the hypothesis that SARS-CoV-2, the virus that causes COVID-19, is directly cytotoxic to pancreatic islet beta cells. This would require binding and entry of SARS-CoV-2 into host beta cells via cell surface co-expression of ACE2 and TMPRSS2, the putative receptor and effector protease, respectively. To define ACE2 and TMPRSS2 expression in the human pancreas, we examined six transcriptional datasets from primary human islet cells and assessed protein expression by immunofluorescence in pancreata from donors with and without diabetes. ACE2 and TMPRSS2 transcripts were low or undetectable in pancreatic islet endocrine cells as determined by bulk or single cell RNA sequencing, and neither protein was detected in alpha or beta cells from these donors. Instead, ACE2 protein was expressed in the islet and exocrine tissue microvasculature and also found in a subset of pancreatic ducts, whereas TMPRSS2 protein was restricted to ductal cells. The absence of significant ACE2 and TMPRSS2 co-expression in islet endocrine cells reduces the likelihood that SARS-CoV-2 directly infects pancreatic islet beta cells through these cell entry proteins.

3.
Lat. American Robot. Symp., Braz. Symp. Robot. Workshop Robot. Educ., LARS-SBR-WRE ; 2020.
Article in English | Scopus | ID: covidwho-1069357

ABSTRACT

We draw complete efforts towards the development of a double hybrid tailsitter UAV system, which is basically composed of a multirotor with 2 electric powertrain sets and a flying wing with combustion powertrain set. Our goal is to design a UAV that diminishes consumption for vertically taking off and landing and to perform the horizontal flight with greatest possible autonomy on flight time and distance. Considering these requirements, the UAV is conceptualized and built as a flying wing propelled by a pusher configuration powerplant, with combustion engine propeller, a multi-engine composed of two powerplant sets with electric motors and propellers, positioned on the leading edge of the wing, and two standard elevation control surfaces and two vertical stabilizers that also have the support function for takeoff and landing. Several takeoff, flight, and transition tests were carried out successfully, but autonomy (time and distance) tests due to the COVID19 pandemic. Results show versatility of the hybrid tailsitter for operations in the flight field, in a limited location. The built prototype has proven to be functional and the hybrid system effective, to date. © 2020 IEEE.

4.
Public Health ; 189: 54-59, 2020 Dec.
Article in English | MEDLINE | ID: covidwho-828245

ABSTRACT

OBJECTIVES: Contact tracing and quarantine are common measures used in the management of infectious disease outbreaks. However, few studies have measured their impact on the control of the COVID-19 pandemic. This study aimed to assess the effectiveness of those measures on reducing transmission of severe acute respiratory syndrome coronavirus 2 in a community setting. STUDY DESIGN: The study design is a retrospective cohort study. METHODS: A retrospective cohort study of COVID-19 cases notified in Eastern Porto from March 1st to April 30th, 2020 was performed. Intervention and control cohorts were defined based on whether cases were subjected to contact tracing and quarantine measures before the laboratory confirmation of disease. The number of secondary cases per index case and the proportion of cases with subsequent secondary cases were the primary outcomes. Secondary outcomes included the time from symptom onset to specimen collection and the number of close contacts. The analysis was stratified according to whether national lockdown measures had already been implemented. RESULTS: The intervention and control cohorts comprised 98 and 453 cases, respectively. No differences were observed concerning primary outcomes. The intervention group had a shorter time between symptom onset and specimen collection (median: 3 days, interquartile range [IQR]: 1-6, vs. median: 5 days, IQR: 2-7, P-value = 0.004) and fewer close contacts (median: 0, IQR: 0-2, vs. median: 2, IQR: 1-4, P-value<0.001). The stratified analysis returned similar results. CONCLUSION: Local public health measures were effective in reducing the time between symptom onset and laboratory diagnosis and the number of close contacts per case. No effect was apparent on secondary case figures, suggesting that further measures may be required.


Subject(s)
Asymptomatic Infections/epidemiology , COVID-19/transmission , Contact Tracing/methods , Disease Transmission, Infectious/prevention & control , Quarantine , SARS-CoV-2 , Adult , Aged , Clinical Laboratory Techniques , Communicable Disease Control/methods , Disease Outbreaks/prevention & control , Female , Humans , Male , Middle Aged , Patient Isolation , Portugal/epidemiology , Public Health , Retrospective Studies
SELECTION OF CITATIONS
SEARCH DETAIL