On the Prairie

Blue sky, constant changing white clouds, green grass, greener trees, the pound, and scattered flowers here and there, chirpings of birds ....What a beautiful day at Oak Point Park & Nature Preserve this morning!

We got there early, ~ 8am, so that we could enjoy the nature in relative solitude. 

We went there for the Nth time now. 

Instead of jogging on the usual paved trail on the perimeter of the prairie, which leads to Bob Woodruff Park, we journeyed onto an unpaved trail into the Prairie - High Meadow trail/Bois D'arc Trail.

Walking into the Prairie,  the wind breezed into our faces, the low grasses swung at our feet, the clouds were high above us, the prairie extended about a mile to the east of us, we felt unconfined, free, and great.

A large patch of poppy flowers at north side of the prairie was into focus. We were so pleased and excited - we lingered there to enjoy the lively colorful flowers, and took a lot of photos as well.

As we marched toward southeast of the prairie, the wild flowers are more sparsely populated - but we heard a lot of bird chirpings in the prairie but barely saw any. We paused, and observed, we saw tiny birds perched on the top of big grasses!

We were in the middle of the prairie: the swing of the grass, the sound of birds, the blue, white, pink, bright yellow flowers ..... what a visual and auditory stimuli! Peaceful, Calming and Soothing.

Can you see a bird in the middle of this picture?

The Prairie at Oak Point - looking to the southwest

North Texas Spring 2020

The alternating rains and shines have made 2020 spring in North Texas really good. The grasses grow fast, trees flourish, flowers bloom, wildlife thrives.

When it shines, the sky is so blue, the clouds are so white.The trees and grass are so green. There was a pink full moon and there have been many splendid Sunrises and gorgeous Sunsets.

 The flowers bloom everywhere, at the community park, in the streets, on the front yards, on trees, in bushes, with a wide variety of colors.

Wildlife thrives this Spring as well. Everyday, we hear calls of cardinals and bluejays from trees, see mockingbirds and house finches swooping in front yards, robbins walking on the lawns, and occasionally woodpecker pecking; and yes quite a few crows and ravens as well. There are more rabbits running around, more squirrells standing in the middle of street chewing on nuts!

There are more wildlife around the pound at our community park - grand egret, turtles, seagulls, grey heron, ducks and ducklings, and out of place, unseasonably appearance of Canadian geesse!

The Sun and the rains nourish the land and life. I enjoy the beautiful sunny days but also appreciate cloudy and rainy days. Even ominous stormy day could bring a different type scene of beauty.

This beautiful spring in North Texas provides me hope and the reason for optimism, circle of life, cycle of nature will continue no matter what happens.

Ignorant or Pragmatic - a covid-19 data analysis

I read in news that there were 8 or 9 states that had not had state wide shelter-in-place order, and in all those reports it was also mentioned that these states all have Republican governors. The most recent tally by CNN is that there are still 7 states remain to be so.

Are those seven governors ignorant or what? I am curious about this and went ahead to perform a data analysis to compare these 7 states to the top 8 states that have most coronavirus infections and death. Here is what I find

table 1

data source: covid-19 data https://www.worldometers.info/coronavirus/country/us/; population, area, population density  - https://www.wikipedia.org/

The 7 states singled out by CNN account for 4.1% of US population, 1.36% total US covid-19 infection, 0.52% of US total covid-19 death.

In contrast, the top 8 states, most of them have Democratic governors, which account for 35.6% US population, 69.04% of total US covid-19 infections, 76.2% of total US covid-19 death.

Simple math shows that the top 8 states, which all have state-wide shelter-in-place, did much worse than the 7 states that do not have state wide shelter-in-place, based on population average. These top 8 states have 5.9 times more infections, 17 times more death!! (On absolute number the disparity is much larger 50 time in infection, 147 times in death.)

What do these comparisons mean?

Shelter-in-place not working? No. Data showed that at national level and state level, shelter-in-place and social distancing work.

Are these 8 states' governors or state governments incompetent? I could not tell by these numbers for sure. There are so many factors that determine the infection rate and death rate.

Epidemiology tells us that the spread of  virus (infection rate) is directly related to the people movement, and population density. In addition to these two factors, death rate is also related the age distribution of local populations. So in general, demographics and people movement are the dominant factors for the spread of virus infections and related death.

Let us look at the top 8 states, all of them have much higher population density, ~ 10x on average, than the 7 no-state-wide-shelter-in-place states; all of them have at least one the following: 1) major hubs for domestic or international air travel, 2) tourism hot spots, 3) metropolitan area with very high population density, not only higher than national average, but also much higher than their individual state average, see table 1 above, and table 2 below.

table 2

State wide shelter in place and social distancing works in the top 8 most infected states and other states that have such order, it flattens the curves, reduces the number death when compared to projected scenarios without such measures.

For those 7 states that do not have state wide shelter-in-place order, it may make sense. Shelter-in-place is a joke if one has NO neighbors in all directions for miles, such is the frequent cases in many of these 7 states. For them social distancing could be good enough for most areas in their states, as long as their state population centers have shelter-in-place order.

Data tells me that the seven state governors are cognizant of their unique situations, large ares, sparsely populated, no state wide shelter-in-place is more based on pragmatism than ideology.

It also tells me that governors of the 8 most infected states may not be incompetent, they do what they have to do to flatten the curves for a much more challenging environment. It is ridiculous when they ask  everyone do the same as they do, or when they refuse to accept lock-down for their highly infected major metropolitan areas or state, such as NYC or tri-state CT-NY-NJ.

No need for one-size-fits-all policy, be pragmatic!

No politicizing covid-19 crises, just solving problems.

Science and Pseudoscience in Coronavirus Epidemics

There are many topics in science to study conronavirus in the fields of biology and epidemiology, from vaccine development to methods to help critically ill patients survive, from control of virus spread to prevention of infection. These are highly specialized fields, and the domain of biologists, medical researchers, and epidemiologists.  As a layman to these two fields, and a mechanical engineer, in this post I summarize my critical review of two specific topics - 1) understanding published statistics on covid-19 and prediction of infections, 2) the distance in social distancing.

Understanding numbers for the Pandemic statistics

CDC and state governments have issued orders and guidelines to contain the spread of the coronavirus.  After a few weeks we saw the obvious exponential increase of total confirmed infections and with about 1 week shift in time, the exponential growth in coronavirus death - see linear scale histograms below.

Near the end of March, the administration announced  that data showed the measures taken were working, and last week the administration/CDC proclaimed to see the light at end of the tunnel.  CDC claims are based on epidemiology science that logarithmic scaled histogram better reveals future trend, and the logarithmic curves for both total cases and death clear showed the slowdown of growth rates in both numbers.

Liner scaled data histogram

Logarithmic data histogram

Those announcements were ridiculed by some news media outlets  - one went as far as claiming "we are not in the tunnel yet". In front of the epidemiology science and real data last week, those outlets and pundits turned out to be the parties that should be ridiculed and disregarded.

There are more sophisticated models to predict the curves of  infections and deaths. Those models, e.g.  IHME model, are phenomenological, statistical in nature. The model predictions tend to have large scatter, high uncertainty (tip - think about weather forecasting models as an analogy). Remember that on March 29th, both CDC and Harvard school of public health announced that the covid-19 death would be at 200K! On April 9th, CDC announced that total death number should be closer to 60K!!

The models seem to predict trends well but not the numbers.

An interesting side story related to understand the statistics. A friend sent an urgent email on Saturday April 11, telling us that worst were yet to come for Texas. I was incredulous - I have been looking at the data daily, Texas has been obviously on a good trajectory. Most recent data April 10th new death, 26, April 11th, new death 19. Both real numbers were lower than previously projected numbers from the IHME model.

IHME projection for Texas

We checked the source of that "worst are yet to come to Texas", it was from CNN, the statement was actually true per the model projection, but what they did not mention in the report was what the worst was for Texas. We checked IHME website, and in fact Texas state government also announced the projection on Friday, peak death rate was to come on April 28th, 66 death per day - see chart above. This compares to what happened at New York, which was discussed in the same CNN report. NY has real peak death rate at 800 so far.  Considering Texas's population is about 1.5 times of New York state's. Texas will be 18 times better than New York on peak death rate per person count. Per current data trend, the real peak death rate should be lower than 66. CNN's sensationalized title and the content of the report gave only partial truth omitting critical information - it distorted the truth, so it was fake news!

Projections are based on rigorous epidemiology models, but there are a lot of assumptions in the models, and the uncertainty in the prediction is very large, as shown in the shaded area in above chart, it is at order of magnitude level. If one is really interested, an in-depth understanding of model predictions as well as raw data are needed so we are not misled by media or any other entities.

What is the proper distance for social distancing?

CDC recommended 6 feet apart for social distancing in order to reduce the spread of conronavirus.  This is mainly based on the understanding that virus is mainly spread through droplets that come out of one's mouth and nose. When an virus carrier speaks, exhales, coughs or sneezes, the droplets travel about three to six feet before gravity pulls them to the ground.

As mentioned in the previous section, in the real world the recommended social distancing and other measures - most significantly "shelter-in-place", has been working its magic.

On March 31, US Today reported a publication by a MIT associate professor, Lydia Bourouiba, in Department of Civil Engineering, in The Journal of the American Medical Association, stating "droplets carrying coronavirus can travel up to 27 feet", and discussed about its potential implications.

USA Today wrote "Her research could have implications for the global COVID-19 pandemic, though measures called for by the Centers for Disease Control and Prevention and the World Health Organization call for six and three feet of space, respectively." A few other outlets reported the JMMA publication, and wondering aloud if 6 feet is enough.

I reviewed the JMMA  publication, and checked  the professor's research background.

First the publication is not a peer reviewed technical paper, it was an opinion piece - JMMA insight.

Second, upon checking the professor's MIT webpage, it indicates that her group has been working on the droplets' fluid dynamics for a few years.

Based on her past publications in technical journals, such as journal of fluid mechanics, a top journal in fluid mechanics, I assumed that the fluid dynamics part of her comments in JMMA insight to be technically correct.

The question is if the work has implications to CDC 6 feet distancing guideline. In the following I show that the JMMA insight has no practical value for social distancing guideline.

A general guideline related to cough and sneeze is "cover your cough". This has been a guideline for many years and is emphasized for covid-19 prevention. When people do cover their cough then the projection of virus carrying droplets are very limited, smaller than 3 feet for most case.

covering your cough prevents virus carrying droplets from traveling far 

For flu and covid-19, people with symptom are requested to stay home before symptoms go away. The 6 feet social distancing is more for prevention of virus spread from asymptomatic people. In this case virus being coughed out is a small probability event. If everyone, or most people (95% +) do their job to cover their cough or sneeze, then increasing social distance becomes a moot point!

The social distancing is to prevent spread of the virus from normal conversation, breathing - in this case 6 feet is more than enough.

So for prevention of virus spread from asymptomatic persons. the most important guidelines are, 1) wash hands frequently after each potential exposure, e.g. touching door knobs, using other's keyboard or mouse ....2) cover one's cough and sneeze.

The projection of droplets carrying virus to 27ft is a small probability event in real world. It is good to know that it can happen under certain conditions*, it is bad to be the base to change social distancing guideline.

It is pseudoscience to claim a single factor experimental results under "ideal condition" to be general enough for policy change. To the least, changing the social distancing guideline based on the MIT work would be misguided.


* how tall the person is, vital capacity, how hard the cough is,wind/air flow direction  ....

Plantations and Mississippi River Delta - Spring Break at NOLA

We went to New Orlean, Louisiana during spring break, March 7th - 11th. On March 12th, the day after we left NOLA, the 1st case coronavirus infection in Louisiana was reported. Two weeks later covid-19 outbreak took place there. NOLA is among the hotspots of coronavirus infection in the nation. By chance or by nature we left NOLA unscathed!

Part of the luck was due to our nature, we prefer outdoor activities over indoor activities except gourmet dining. In fact we were out of the city every day when we were there.

In addition to swamp boat tour, we visited Oak Alley plantation,  rode steamboat on Mississippi river for a lunch history river cruise, and drove to the mouth of Mississippi river.

Oak Alley Plantation

This plantation is a more well known and more frequently visited plantation in NOLA and it is located at west bank of Mississippi river. When we talk about plantations, we talk about sugar canes and sugar, slaves and slave masters about 160 years ago. The oak alley plantation was built and owned by Jacques and Celina Roman.

When we walked into the plantation, through the backyard parking lot, the first buildings in sight were three small cabins, where slaves lived. One person a cabin, not too bad I thought. It turned out they were for slave nanny and chef, who worked for the masters in the main house during the day. Slaves for field labor lived in less conditioned log cabins.

cabins for slaves

The mansion is big even by today's standard. Two things in the building caught our attentions: 1) the beds, chairs .... everything seems to be just a little bit smaller than what we have now days, 2) there is a wood frame hanging over the main dining room table. The feel that furnitures were smaller was not our imagination, but a fact because people then was shorter, 11 cm shorter according to BBC news. The wood frame over the dining table served as a fan - when in use there was cloth hang from it, and a slave standing at the corner of the dining room pull a rope up and down to swing the frame to produce breeze for masters and their guest.

the mansion

The most impressive feature at the plantation to me was the oak alley as shown below, which had huge oak trees lined alley, which lead to the main road by the west band of Mississippi river.

The trees are magnificent and felt exotic, intriguing.

oak alley

Mississippi River Historic River Cruise

One thing I would like to do was to experience the Mississippi river, the longest river in North America and the 4th longest in the world. We took the river cruise on our send full day at NOLA. The cruise terminal is walking distance from the hotel we stayed at French Quarter.

The main destination of the river cruise is Chalmette Battlefield. On the way there we enjoyed the view of riverfront NOLA, we saw that Domino Sugar plants with tattered windows prominently standing by the river after 100 years, we heard our on-board historian/tour guide proudly announced that Domino sugar produced 1 million ton of sugar last year!

Creole Queen Steam boat

Bridge over Mississippi at New Orlean

Riverfront NOLA

Domino Sugar - 

Chalmette Battlefield, the site of the January 8, 1815, Battle of New Orleans, the last great battle of the War of 1812 between the United States and Britain. We walk onto the battlefield, looked up the memorial monument, and stood by the cannons. It is interesting to note that the general of the American army was Andrew Jackson, the 7th president of United States.

Monument

Chalmette Battlefield

The Mississippi River Delta

On march 10th, our last full day at NOLA, we drove to Mississippi river delta, hopping to get to the mouth of the river. We drove all the way to the end of highway 23. Unfortunately we could not really see the wetland or Mississippi river from the highway.

We stopped on the road a few times to see the swamps and Mississippi river. One time we stopped the car by the highway and walked on to the levee to see the Mississippi river. A state trooper followed us onto the levee, when he was informed that we just want to look at the river and the port, he told us we could drive on the levee to the riverbank.

The swamps are full of water fowles - mostly pelicans, egrets, ducks as well as many dark feathered birds that I could not name. The bayou near the end of the road was especially beautiful and had many pelicans, egrets and herons, we stayed there for quite some time to watch and take pictures.

One has to take a boat to see Mississippi river pour into Gulf of Mexico. We did not have such a chance.

marsh land

pelicans and ducks in wetland

swamp of  Mississippi delta 

Pelicans rest on trees

The harbor at the red dot in the following photo

Mississippi River Delta

Road to the mouth of Mississippi river