droplet evaporation

where is the safest place to have a large droplet evaporate?

It is the essence of disease transmission that infectious viruses are carried by droplets. After being exhaled from the host, the droplets will conduct heat, participate in mass transfer, and undergo an evaporation exchange with the environment. The viral survival condition, such as saltwater, nutrient, salt, pH, temperature, and humidity balance, are significantly influenced by various environmental factors. The viruses can only enter the host “luckily” and cause infection when the concentration is sufficient and the virus is still alive, which is unfortunate for the susceptible population. Thus, the different risk of when and how to contact the infectious viruses is the most important question that should be answered, to provide a reference for early isolation and the mask dispute.

Based on the different particle sizes, we conducted an in-depth review on the physical processes and transmission risks of viral infections caused by infectious droplets at different time points. We found that the viral load of large droplets was several orders of magnitude larger than that of small droplets. The disease transmission ability of large droplets at the initial moment is significantly higher than that of small droplets. Furthermore, during the transmission process, the original large droplets evaporation takes longer, and the survival condition balance of active viruses is better maintained, and becomes a high-risk small droplet nuclei carrying a massive number of active viruses after evaporation. Compared with the original small droplets, whose internal viruses are quickly evaporated and inactivated, the risk difference of disease transmission between the two is even greater, which also confirmed the dominant position of large droplets in disease transmission.

posterior vitreous detachment

A posterior vitreous detachment (PVD) is a condition of the eye in which the vitreous membraneseparates from the retina. It refers to the separation of the posterior hyaloid membrane from the retina anywhere posterior to the vitreous base (a 3–4 mm wide attachment to the ora serrata).

The condition is common for older adults; over 75% of those over the age of 65 develop it. Although less common among people in their 40s or 50s, the condition is not rare for those individuals. Some research has found that the condition is more common among women.

When this occurs there is a characteristic pattern of symptoms:

• Flashes of light (photopsia)

• A sudden dramatic increase in the number of floaters

• A ring of floaters or hairs just to the temporal side of the central vision

As a posterior vitreous detachment proceeds, adherent vitreous membrane may pull on the retina. While there are no pain fibers in the retina, vitreous traction may stimulate the retina, with resultant flashes that can look like a perfect circle.

If a retinal vessel is torn, the leakage of blood into the vitreous cavity is often perceived as a "shower" of floaters. Retinal vessels may tear in association with a retinal tear, or occasionally without the retina being torn

the difficulties of math

Is The Pandemic 10 Times Worse Than You Think?

…The model's conclusion: On any given day, the actual number of active cases — people who are newly infected or still infectious — is likely 10 times that day's official number of reported cases.

https://covid.cdc.gov/covid-data-tracker/#cases_casesper100klast7days

26,939,515 x 10 = 260,939,515

Estimated United States population 330,074,711.

260,939,516 / 330,074,711

= 79.1 % already infected

However the above comes from reading the headline. Looking at the underlining more conservative presentation of data:

The sustained periods of high transmission in the U.S. also mean that by now, quite a large share of the U.S. population has been infected beyond what the tallies of reported cases would indicate. Nationwide, Shaman estimates that about 120 million people have now been infected, just over a third of the U.S. population.

using the above statistic:

120,000,000 estimated cases / 26,963,516 CDC cases

= 4.45 times more cases than CDC has reported.

Would this not also equally mean that COVID-19 is 77.5% less deadly than being reported?

i.e. If there are five times the infections than have been currently reported by CDC, would that not also mean that percentage fatality rate has to be 20 percent of what current CDC is been reporting?

Accuracy in infection and mortality data is if course important for understanding and making policy decisions.

It would seem the math points toward herd immunity of a less (than originally suspected) fatal disease. Else, the only things that would justify an ever-present-ongoing-policy of recommending/requiring multiple masks, social distancing, and business/social lockdowns, where the vast majority of individuals have either had already COVID and recovered or been vaccinated for it, would be concerns of short-term immunity, and/or mutations, and/or the often cited “asymptomatic” spreading. Those topics deserve further study/exploration.

the difference between doing what is easy versus what is effective

The streetlight effect, or the drunkard's search principle, is a type of observational bias that occurs when people only search for something where it is easiest to look. Both names refer to a well-known joke:

A policeman sees a drunk man (wearing a pair of goggles) searching for something under a streetlight and asks what the drunk has lost. He says he lost his keys (the policeman puts on a pair of goggles) and they both look under the streetlight together. After a few minutes the policeman asks if he is sure he lost them here, and the drunk replies, no, and that he lost them in the park. The policeman asks why he is searching here, and the drunk replies, "this is where the light is".

The anecdote goes back at least to the 1920s, and has been used metaphorically in the social sciences since at least 1964, when Abraham Kaplan referred to it as "the principle of the drunkard's search". The anecdote has also been attributed to Nasreddin. According to Idries Shah, this tale is used by many Sufis, commenting upon people who seek exotic sources for enlightenment.

loss of smell as a diagnostic

If you lose your sense of smell, you'll miss more than a variety of scents. Without a good sense of smell, you may find that food tastes bland and it's hard to tell different foods apart. Loss of smell can be partial (hyposmia) or complete (anosmia), and may be temporary or permanent, depending on the cause.

A stuffy nose from a cold is a common cause for a partial, temporary loss of smell. A blockage in the nasal passages caused by a polyp or a nasal fracture also is a common cause. Normal aging can cause a loss of smell too, particularly after age 60.

Loss of smell caused by colds, allergies or sinus infections usually clears up on its own after a few days. If this doesn't happen, consult your doctor so that he or she can rule out more-serious conditions.

Additionally, loss of smell can sometimes be treated, depending on the cause. Your doctor may give you an antibiotic to treat a bacterial infection, or remove anything blocking your nasal passage. But in some cases, loss of smell can be permanent.

Prevalence and 6‐month recovery of olfactory dysfunction: a multicentre study of 1363 COVID‐19 patients

Mild patients were defined as patients without evidence of viral pneumonia or hypoxia and were commonly home‐managed and followed. Moderate COVID‐19 patients had clinical signs of pneumonia (fever, cough, dyspnoea, fast breathing) but no sign of severe pneumonia (including SpO2 ≥ 90% on room air).

Severe COVID‐19 patients were defined as individuals with clinical signs of pneumonia plus one of the following: respiratory rate > 30 breaths/min; severe respiratory distress; or SpO2 < 90% on room air. According to the centre and the availability of local healthcare resource, moderate and severe patients were home‐managed (moderate) or hospitalized in non‐intensive care units (ICU) vs. ICU. Patients with critical disease had acute respiratory distress syndrome (ARDS), sepsis or septic shock and were hospitalized in ICU. Patients with OD were followed to assess the recovery olfactory rates and the duration of OD.

Conclusions:

Amongst the 2581 patients, 1916 reported self‐reported OD (74.2%).

[Meaning 25% did not report loss of smell. Of those reporting olfactory dysfunction the vast majority were those diagnosed as having a mild case of COVID.]

The prevalence of self‐reported OD was 85.9%, in patients deemed to have a mild case of COVID.

The prevalence of self‐reported OD was 4.5%, in patients deemed to have moderate case of COVID.

The prevalence of self‐reported OD was 6.9%, in patients deemed to have a severe‐to‐critical case of COVID.

Common Cold

Each year in the United States, millions of people get the common cold. Adults have an average of 2-3 colds per year, and children have even more.

• Many viruses can cause colds, but rhinoviruses are most common. Infections spread through the air and close personal contact.

In the course of a year, people in the U.S. suffer 1 billion colds, according to some estimates.

How can you tell the difference between a cold and the flu?

Because colds and flu share many symptoms, it can be difficult (or even impossible) to tell the difference between them based on symptoms alone.

The symptoms of flu can include fever or feeling feverish/chills, cough, sore throat, runny or stuffy nose, muscle or body aches, headaches and fatigue (tiredness). Cold symptoms are usually milder than the symptoms of flu. People with colds are more likely to have a runny or stuffy nose. Colds generally do not result in serious health problems.

What is the difference between Influenza (Flu) and COVID-19?

Similarities:

Both COVID-19 and flu can have varying degrees of signs and symptoms, ranging from no symptoms (asymptomatic) to severe symptoms. Common symptoms that COVID-19 and flu share include:

• Fever or feeling feverish/chills

• Cough

• Shortness of breath or difficulty breathing

• Fatigue (tiredness)

• Sore throat

• Runny or stuffy nose [can cause loss of smell as mentioned previously]

• Muscle pain or body aches

• Headache

• Some people may have vomiting and diarrhea, though this is more common in children than adults

Flu

Flu viruses can cause mild to severe illness, including common signs and symptoms listed above.

Flu Symptoms

COVID-19

COVID-19 seems to cause more serious illnesses in some people. Other signs and symptoms of COVID-19, different from flu, may include change in or loss of taste or smell. [Which statistically would more likely indicate a mild case of COVID if at all, and if not from a cold or mild flu or other.]

[As there is so much cross-over on symptoms, one can appreciate why accurate diagnosis and testing is important.]

see also:

What's the Frequency?

Weather impact on airborne coronavirus survival: Physics of Fluids

…the steady-state relationships induce significant errors and must not be applied in unsteady saliva droplet evaporation. The classical theory introduces substantial deviations in Nu and Sh values when increasing the Reynolds number defined at the droplet scale. The effects of relative humidity, temperature, and wind speed on the transport and viability of CoV in a cloud of airborne saliva droplets are also examined. The results reveal that a significant reduction of virus viability occurs when both high temperature and low relative humidity occur. The droplet cloud’s traveled distance and concentration remain significant at any temperature if the relative humidity is high, which is in contradiction with what was previously believed by many epidemiologists. The above could explain the increase in CoV cases in many crowded cities around the middle of July (e.g., Delhi), where both high temperature and high relative humidity values were recorded one month earlier (during June). Moreover, it creates a crucial alert for the possibility of a second wave of the pandemic in the coming autumn and winter seasons when low temperatures and high wind speeds will increase airborne virus survival and transmission.