Thursday, January 14, 2021

My "one good thing" of 2020: "Converting" sports, i.e. downhill skiing => cross-country & pool swimming => ocean swimming

During the COVID pandemic, I've tried hard to go outside and run around. It's a bit of escape for me and a way to get out of my home office - AKA upholstered cell. Unfortunately, many of the activities that I like doing outside are now very difficult to do, viz: pool swimming, going to the gym, taking bike and skiing trips, &c. Luckily, I've "converted" a number of these to related ones that are relatively easy to do. In particular, I've been able to convert my pool swimming into wetsuit ocean swimming and my downhill skiing into cross country skiing. Also, I've enjoyed lots of hiking. For me, this has been the "one good thing" about the 2020 pandemic - quoting the words from Nature's Coronapod podcast.

For reference, I've just listed below some key tidbits for myself related to these activities.

1. Ocean swimming

The key things here are the air and water temperature, the tides, and wave height. I list below some of these parameters with timings for some swims I took during the summer and fall. You can see with a wetsuit, particularly a thick one, it's possible to go in when it's pretty cold.

2. Cross-country skiing

Here I was delighted to find that a nearby bike path can easily be turned into a nice cross-country ski trail with an appreciable amount of snow. This is about a 10-minute ski from my house, and I list the timings back and forth on the trail, with a picture.

3. Hiking

I've tried to explore many neighboring New Haven-area trails. I list some below.

Sunday, December 27, 2020

Thoughts on Wohlleben's Hidden Life of Trees: Insights about tree science & society

I read Peter Wohlleben's book The Hidden Life of Trees with great interest. Anyone who enjoys being around trees and is also interested in science will cherish this book. It provides many insights and a real appreciation for trees.

The insights fall into three categories. The first is the social life of trees, something I didn't appreciate before. It appears that trees communicate with each other through their root systems and through the fungi that interconnect them. They also use scents and chemicals to communicate with each other. This communication can involve a mother tree schooling the younger trees in their growth, inhibiting them from growing too quickly. It also has a competitive aspect where, for instance, a Beech tree neighboring an Oak might compete with it for water and eventually sunlight. Trees that are together in a forest can modulate their overall climate and protect each other much better than an isolated tree. In fact, forests overall are responsible for much of water's movement throughout the earth's ecosystem.

The second insight from the book is the basic science underlying how trees work. Here, Wohlleben talks about how water makes its way up trees. The full process is still a mystery, but Wohlleben describes the basic processes of capillary action, osmosis, and transpiration. He also talks about photosynthesis chemistry and why we see most trees as green but a few as red.

The final insight of the book is the practical things to know when you are in the forest. Why do you see mistletoe on the top of a tree crown? What is the effect of ivy curling around a tree as a somewhat parasitic agent? Why is moss usually on the rainy side of a tree? And, when a tree dies, why do you often see other things come up in its place?

Overall, this was a very illuminating book that I enjoyed reading, and I continue to think about concepts from this book when I take walks in the woods.

Book: Hidden Life of Trees 

Author: Peter Wohlleben 

My quotes: 

My tag (associated with the book): 

Saturday, December 12, 2020

Thoughts on McPhee's Basin & Range: Geological Cliff Notes for I-80

I read John McPhee's book Basin and Range with great interest. In a sense, the book travels across the United States from New York to California, including the basins and ranges in between. More specifically, it gives a geological history of the trip across the United States from New York to San Francisco, mostly on Route 80, going through all the different land formations.  

The book also travels through geologic history from the present back to the Triassic and Permian periods, covering the various geological epochs. Finally, it travels up and down mountains through elevation changes between basins and ranges. 

The book provided a great introduction to geology. I was particularly interested in how it explained how gold and silver deposits arise from these minerals being dissolved and then precipitating out of solution and what it was like during the Nevada Silver Rush in the 19th century. 

Overall, Basin and Range is a great read, which I would highly recommend.

Book: Basin and Range

Author: John McPhee 

My quotes: 

My tag (associated with the book): 

Monday, December 07, 2020

Thoughts on Lewis's Undoing Project: A psychological analysis illuminating psychological science

I read with great interest Michael Lewis's book called The Undoing Project. The book focuses on a famous partnership between psychologists Daniel Kahneman and Amos Tversky that revolutionized many aspects of psychological science and economics. 

 The book goes through the personal details of their friendship and provides insights into their scientific advances. As a non-psychologist, I was impressed with the intuitive way the book described Kahneman and Tversky's notions. I was particularly taken by how this pair found hidden biases in our decision-making and thinking processes by posing simple numerical challenges. One of these challenges was simply determining the product of multiple numbers and then determining the product with the numbers arranged in reverse. Kahneman and Tversky discovered that people tend to estimate these products differently. Another interesting challenge demonstrated how people estimate the significance of one number being larger than another differently than that of a group of numbers, discounting our greater certainty for a group. In another example, they found that if one flips losses to gains symmetrically, people's choices do not fall symmetrically; rather, people tend to weight gains versus losses quite differently. Finally, Kahneman and Tversky found that people give a much higher weight to a list of people they know or have heard of compared to a list of random names, when given two lists of names. 

Altogether, I found this an interesting book that teaches some simple psychological science concepts while providing an entertaining portrait of two great thinkers. Overall, a good read that I would highly recommend.

The Undoing Project: A Friendship That Changed Our Minds

My quotes:
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Sunday, August 23, 2020

Thoughts on Smith's Standard Deviations: Makes Statistical Blunders Easy to Spot

I read Gary Smith's book Standard Deviations with great interest. The book makes the complex issue of statistical deceptions and mistakes easy to understand through simple language and entertaining examples. Smith covered statistical cases ranging from the obvious (e.g., misleading graphs) to much more subtle (e.g., mistakes where people see apparent clusters in random data without accounting for various confounding effects). I especially liked the way Smith tackled the subtle examples. He went over the many instances in training models and using them to mine data where the process becomes highly sensitive to various parameters such as binning. He also pointed out mistakes such as not sufficiently testing multiple hypotheses and not correcting for confounders. He described one obvious confounder in detail - how the population is always increasing and how things correlated with it, in turn, seem to be correlated with each other. For instance, one can see an ever-increasing amount of diaper and rug sales, but these are just correlated with overall population growth rather than being correlated with each other. There is also a nice discussion of survivorship bias -- how one does statistics only on those that survive and not the entire original cohort. This was most notably seen in the famous case of the vulnerable parts of World War II planes, determined only from the planes returning from combat. Overall, I found this book very easy to read, and I would recommend it to anyone wanting to avoid statistical blunders.

Standard Deviations: Flawed Assumptions, Tortured Data, and Other Ways to Lie with Statistics 

Sunday, August 02, 2020

Some defunct links to various tagging sites

Old bookmarks (Dec. '06 to Sep. '11), including article clips (mostly popular)

For Delicious, here are some definitions of my public tags. Notice, how it contains a subdivision into tags that are applicable to bookmarks, blogs, images, etc using yet more tags. It also contains pointers to tops of link clusters (overviews and centers)

Backflip bookmarks (broken): Quicklinks, current ones, sent-email-about-this

Digg history

Sunday, June 21, 2020

Thoughts on Christian's & Griffiths' Algorithms to Live By: Great Intuition for Important Concepts

I read with great interest Brian Christian and Tom Griffiths' Algorithms To Live By. The book does a fantastic job of connecting abstruse computer algorithms to real-life situations and intuitions. I couldn't stop jotting down various tidbits that I wanted to remember; I advise people to read it!

The book begins with a discussion of the stopping problem. It relates this to familiar situations in life, such as when people need to decide on a partner, rent a home, or otherwise gather information to make a decision. Then, the book focuses on sorting, connecting this to how people arrange books on a shelf, and also to how teams sort themselves in tournaments. The book also highlights how certain sorting algorithms are more robust to noise than others (eg bubble vs. merge sort).

The book discusses ways of storing information, providing useful hints on how to organize one's closet based on the LRU cache. The discussion of Bayesian mathematics is excellent. It explains how one uses different priors in common-sense reasoning; for instance, movie revenues follow a scale-free prior, whereas human age is centered on a mean, using a Gaussian prior.

The book also talks about various randomized algorithms, such as Monte Carlo and simulated annealing, giving a sense of how sampling randomly allows one to tackle problems that could not be addressed otherwise. Other techniques, such as constraint relaxation, also enable one to deal with intractable problems and start to get at solutions.

The book ends with chapters on networking and game theory. The discussion on networking highlights the importance of buffers and how our inundation of messages in the modern world reflects that we can essentially keep everything in a buffer (i.e. no tail drop). One prominent omission for me was that there was no discussion of network science, the analysis of connectivity patterns in large networks (e.g. hubs and bottlenecks). The section on game theory relates Alan Turing's famous discussion of the halting problem to the intractable regress that one has in playing poker or trying to estimate a stock price, where one is not thinking only of one's own estimation but what one's opponent thinks - and so on.

The book concludes with the notion of computational kindness, where one tries to interact with others so as to minimize the amount of computations they have to do. Altogether, the book was a great read that I would highly recommend to others.

Algorithms to Live By: The Computer Science of Human Decisions 0th Edition, Kindle Edition
by Brian Christian (Author), Tom Griffiths (Author)


My quotes:

My tag (associated with the book):