Computational characterization of inhaled droplet transport to the nasopharynx

AbstractHow human respiratory physiology and the transport phenomena associated with inhaled airflow in the upper airway proceed to impact transmission of SARS-CoV-2, leading to the initial infection, stays an open question. An answer can help determine the susceptibility of an individual on exposure to a COVID-2019 carrier and can also provide a preliminary projection of the still-unknown infectious dose for the disease. Computational fluid mechanics enabled tracking of respiratory transport in medical imaging-based anatomic domains shows that the regional deposition of virus-laden inhaled droplets at the initial nasopharyngeal infection site peaks for the droplet size range of approximately 2.5–19 $$\upmu $$ μ . Through integrating the numerical findings on inhaled transmission with sputum assessment data from hospitalized COVID-19 patients and earlier measurements of ejecta size distribution generated during regular speech, this study further reveals that the number of virions that may go on to establish the SARS-CoV-2 infection in a subject could merely be in the order of hundreds.

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Computational characterization of inhaled droplet transport in the upper airway leading to SARS-CoV-2 infection

10.1101/2020.07.27.20162362 ◽

2020 ◽

Cited By ~ 3

Author(s):

Saikat Basu

Keyword(s):

Size Range ◽

Upper Airway ◽

Respiratory Physiology ◽

Computational Fluid Mechanics ◽

Assessment Data ◽

Infectious Dose ◽

Initial Infection ◽

Droplet Transport ◽

Regional Deposition

ABSTRACTHow human respiratory physiology and the transport phenomena associated with the inhaled airflow therein proceed to impact transmission of SARS-CoV-2, leading to the initial infection, is an open ques- tion. An answer can help determine the susceptibility of an individual on exposure to a COVID-2019 car- rier and can also quantify the still-unknown infectious dose for the disease. Synergizing computational fluid mechanics enabled tracking of respiratory transport in medical imaging-based anatomic domains, with sputum assessment data from hospitalized COVID-19 patients and earlier measurements of ejecta size distribution during regular speech – this study shows that the regional deposition of virus-laden inhaled droplets at the initial nasopharyngeal infection sites peaks for the droplet size range of 2.5 – 19 microns, and reveals that the number of virions that go on to establish the infection can be merely in the order of hundreds.

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On the similarity to nonnegative and Metzler Hessenberg forms

Special Matrices ◽

10.1515/spma-2020-0140 ◽

2021 ◽

Vol 10 (1) ◽

pp. 1-8

Author(s):

Christian Grussler ◽

Anders Rantzer

Keyword(s):

Standard Form ◽

Complete Characterization ◽

Nonnegative Matrices ◽

Positive Systems ◽

Third Order ◽

Hessenberg Form ◽

Hessenberg Matrices ◽

Open Question ◽

Order Continuous

Abstract We address the issue of establishing standard forms for nonnegative and Metzler matrices by considering their similarity to nonnegative and Metzler Hessenberg matrices. It is shown that for dimensions n 3, there always exists a subset of nonnegative matrices that are not similar to a nonnegative Hessenberg form, which in case of n = 3 also provides a complete characterization of all such matrices. For Metzler matrices, we further establish that they are similar to Metzler Hessenberg matrices if n 4. In particular, this provides the first standard form for controllable third order continuous-time positive systems via a positive controller-Hessenberg form. Finally, we present an example which illustrates why this result is not easily transferred to discrete-time positive systems. While many of our supplementary results are proven in general, it remains an open question if Metzler matrices of dimensions n 5 remain similar to Metzler Hessenberg matrices.

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The randomized communication complexity of revenue maximization

ACM SIGecom Exchanges ◽

10.1145/3505156.3505165 ◽

2021 ◽

Vol 19 (2) ◽

pp. 75-83

Author(s):

Aviad Rubinstein ◽

Junyao Zhao

Keyword(s):

Lower Bounds ◽

Communication Complexity ◽

Social Choice Rule ◽

Valuation Function ◽

Optimal Auctions ◽

Incentive Compatible ◽

First Approximation ◽

Exponential Separation ◽

Open Question

We study the communication complexity of incentive compatible auction-protocols between a monopolist seller and a single buyer with a combinatorial valuation function over n items [Rubinstein and Zhao 2021]. Motivated by the fact that revenue-optimal auctions are randomized [Thanassoulis 2004; Manelli and Vincent 2010; Briest et al. 2010; Pavlov 2011; Hart and Reny 2015] (as well as by an open problem of Babaioff, Gonczarowski, and Nisan [Babaioff et al. 2017]), we focus on the randomized communication complexity of this problem (in contrast to most prior work on deterministic communication). We design simple, incentive compatible, and revenue-optimal auction-protocols whose expected communication complexity is much (in fact infinitely) more efficient than their deterministic counterparts. We also give nearly matching lower bounds on the expected communication complexity of approximately-revenue-optimal auctions. These results follow from a simple characterization of incentive compatible auction-protocols that allows us to prove lower bounds against randomized auction-protocols. In particular, our lower bounds give the first approximation-resistant, exponential separation between communication complexity of incentivizing vs implementing a Bayesian incentive compatible social choice rule, settling an open question of Fadel and Segal [Fadel and Segal 2009].

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New Results on Degree Sequences of Uniform Hypergraphs

The Electronic Journal of Combinatorics ◽

10.37236/3414 ◽

2013 ◽

Vol 20 (4) ◽

Cited By ~ 9

Author(s):

Sarah Behrens ◽

Catherine Erbes ◽

Michael Ferrara ◽

Stephen G. Hartke ◽

Benjamin Reiniger ◽

...

Keyword(s):

Efficient Algorithm ◽

Necessary Conditions ◽

Degree Sequence ◽

Sufficient Conditions ◽

Degree Sequences ◽

Uniform Hypergraph ◽

Graphic Sequence ◽

Uniform Hypergraphs ◽

Open Question

A sequence of nonnegative integers is $k$-graphic if it is the degree sequence of a $k$-uniform hypergraph. The only known characterization of $k$-graphic sequences is due to Dewdney in 1975. As this characterization does not yield an efficient algorithm, it is a fundamental open question to determine a more practical characterization. While several necessary conditions appear in the literature, there are few conditions that imply a sequence is $k$-graphic. In light of this, we present sharp sufficient conditions for $k$-graphicality based on a sequence's length and degree sum.Kocay and Li gave a family of edge exchanges (an extension of 2-switches) that could be used to transform one realization of a 3-graphic sequence into any other realization. We extend their result to $k$-graphic sequences for all $k \geq 3$. Finally we give several applications of edge exchanges in hypergraphs, including generalizing a result of Busch et al. on packing graphic sequences.

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Characterization of infectious dose and lethal dose of two strains of infectious hematopoietic necrosis virus (IHNV)

Virus Research ◽

10.1016/j.virusres.2015.12.020 ◽

2016 ◽

Vol 214 ◽

pp. 80-89 ◽

Cited By ~ 6

Author(s):

Douglas G McKenney ◽

Gael Kurath ◽

Andrew R Wargo

Keyword(s):

Lethal Dose ◽

Infectious Hematopoietic Necrosis Virus ◽

Necrosis Virus ◽

Infectious Dose ◽

Infectious Hematopoietic Necrosis

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Difficult airway in the Paediatric Intensive Care Unit

Challenging Concepts in Paediatric Critical Care ◽

10.1093/med/9780198794592.003.0010 ◽

2020 ◽

pp. 115-128

Author(s):

Elizabeth O’Donohoe ◽

Thomas Breen ◽

Fiona Reynolds

Keyword(s):

Intensive Care Unit ◽

Intensive Care ◽

Rapid Sequence Induction ◽

Upper Airway ◽

Difficult Tracheal Intubation ◽

Respiratory Physiology ◽

Safe Management ◽

Rapid Sequence ◽

Sequence Induction ◽

Difficult Airways

Children with difficult airways can come to significant harm if not appropriately assessed and managed. Chapter 10 discusses the signs of airway compromise in children and indications for intubation in the Intensive Care Unit (ICU). The role of the paediatric airway in respiratory physiology is examined. Recognizing a difficult paediatric airway is vital in the ICU—common causes of upper airway obstruction are listed and techniques for assessing paediatric airways addressed. The choice of drugs for rapid sequence induction in the Paediatric ICU is explained, and algorithms for the management of the unanticipated difficult tracheal intubation and ‘cannot intubate, cannot ventilate’ illustrated. Finally, the chapter includes the fundamental concepts of team brief, checklists, and crisis resource management in the safe management of difficult airways in children.

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Characterization of cellulose acetate based on empty fruit bunches and dried jackfruit leaves as replacement candidates for microbeads

E3S Web of Conferences ◽

10.1051/e3sconf/20186704024 ◽

2018 ◽

Vol 67 ◽

pp. 04024

Author(s):

Dewi Tristantini ◽

Andersen Yunan

Keyword(s):

Water Absorption ◽

Cellulose Acetate ◽

Size Range ◽

Acid Anhydride ◽

Particle Sizes ◽

Oil Absorption ◽

Empty Fruit Bunches ◽

Alternative Sources ◽

Beauty Products

Scrubs used in other skin care and beauty products usually contain tiny fine grains of synthetic polymer called microbeads that usually pose threats to marine environment. Empty Fruit Bunches (EFB) and Dried Jackfruit Leaves (DJL) as organic and environmentally friendly can be alternative sources for polymer microbeads. Cellulose acetate is prepared by acetylation reaction between cellulose and acetic acid anhydride. Cellulose from EFB and DJL was extracted through a process of delignification with 12% NaOH treatment for EFB and 10% for DJL to obtain maximum yields of 38.964% and 14.449% respectively, followed by bleaching using peroxide 10 %. The formed cellulose acetate with 88.5% and 79.7% yield respectively is then filtered using a sieve mash 60 and 80 to obtain particle sizes ranging that are in the microbeads size range. The density test resulting in 0.73 g/cm3 and 0.52 g/cm3 respectively for EFB and DJL. Then, physical characteristic test was done by water and oil absorption test with variation at 25°C and 40°C. EFB at 25°C and 40°C shows water absorption at 23.39% and 26.09% and oil absorption at 7.59% and 13.95%. DJL at 25°C and 40°C shows water absorption at 22.56% and 27.32% and oil absorption at 13.09% and 15.36%.

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Drug-Induced Sleep Endoscopy: Clinical Application and Surgical Outcomes

Healthcare ◽

10.3390/healthcare7030100 ◽

2019 ◽

Vol 7 (3) ◽

pp. 100 ◽

Cited By ~ 2

Author(s):

Vito ◽

Cammaroto ◽

Chong ◽

Carrasco-Llatas ◽

Vicini

Keyword(s):

Surgical Outcomes ◽

Acoustic Analysis ◽

Three Dimensional ◽

Upper Airway ◽

Sleep Endoscopy ◽

Drug Induced ◽

Drug Induced Sleep Endoscopy ◽

Therapeutic Decision Making ◽

Open Question ◽

Insight Into

The visualization of the level and pattern of apnea and hypopnea events is of pivotal importance in the diagnosis and therapeutic decision-making for sleep-disordered breathing (SDB). There are numerous techniques available to assess upper airway obstruction, which include imaging, acoustic analysis, pressure transducer recording, and endoscopic evaluation. Drug-induced sleep endoscopy (DISE) is a diagnostic tool that allows the dynamic, three-dimensional evaluation of the patterns of vibration and collapse of the upper airway of SDB patients. DISE may change the initial surgical planning in a high percentage of cases. A universally accepted and methodologically standardized DISE could provide significant insight into its role to improve surgical outcomes. However, up to now the ideal DISE protocol remains an open question.

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