, 2 min read
Under many operating systems, you can send data from from one process to another using ‘pipes’. The term ‘pipe’ is probably used by analogy with plumbing and we often use the the symbol ‘|‘ to represent a pipe (it looks like a vertical pipe). Thus, for example, you can sort a file and…
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Researchers built a microscope that might be 10 times better than the best available microscopes. Subsidizing college education can lower earnings due to lower job experience: The Post 9/11 GI Bill (PGIB) is among the largest and most generous college subsidies enacted thus far in the U.S. (…)…
, 3 min read
Software developers are often concerned with the memory usage of their applications, and rightly so. Software that uses too much memory can fail, or be slow. Memory allocation will not work the same way under all systems. However, at a high level, most modern operating systems have virtual memory…
, 4 min read
When designing an index, a database or a search engine, you frequently need to compute the union of two sorted sets. When I am not using fancy low-level instructions, I have most commonly computed the union of two sorted sets using the following approach: v1 = first value in input 1 v2 =…
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We use CRISPR, a state-of-the-art gene editing technique, to edit the genes of live human patients in a clinical trials. A clinical trial has begun regarding an HIV vaccine. If you choose to forgo meat to fight climate change, you may lower your individual’s lifetime warming contribution by 2 to…
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JSON is the de facto standard for exchanging data on the Internet. It is relatively simple text format inspired by JavaScript. I say “relatively simple” because you can read and understand the entire JSON specification in minutes. Though JSON is a concise format, it is also better used over a…
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Reportedly, half of us own a smartphone. It is often reported that women or visible minority earn less money. However, ugly people are doing comparatively even more poorly. We have highly efficient and cheap solar panels. However, we must also quickly dispose of them after a few years which leads…
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Lev Reyzin says that working too long on a problem might be unproductive: I, personally, have diminishing (or negative?) returns to my creative work as I explicitly work on a problem past some amount of time. I often have insights coming to me out of nowhere while I’m relaxing or enjoying…
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We completed the sequencing of the human genome. AstraZeneca’s drug Lynparza cut combined risk of recurrence of breast cancer or death by 42% among women in study. Glycine and N-acetylcysteine supplementation improves muscle strength and cognition. We found Egypt’s ancient capital. It has…
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I my previous blog post, I documented how one might proceed to compute the number of digits of an integer quickly. E.g., given the integer 999, you want 3 but given the integer 1000, you want 4. It is effectively the integer logarithm in base 10. On computers, you can quickly compute the integer…
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Suppose I give you an integer. How many decimal digits would you need to write it out? The number ‘100’ takes 3 digits whereas the number ’99’ requires only two. You are effectively trying to compute the integer logarithm in base 10 of the number. I say ‘integer logarithm’ because you…
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All models are wrong, but some are useful is a common saying in statistics. It does not merely apply to statistics, however. It is general observation. Box (1976) wrote an influential article on the topic. He says that you make progress by successively making models followed by experiments,…
, 4 min read
Most computer chips today in flagship phones and computers use a process based on a 5 nm or larger resolution. Finer resolutions usually translate into lower energy usage and lower heat production. Given that many of our systems are limited by heat or power, finer resolutions lead to higher…
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Suppose that you give me two ASCII strings having the same number of characters. I wish to compute efficiently the number of matching characters (same position, same character). E.g., the strings ‘012c’ and ‘021c’ have two matching characters (‘0’ and ‘c’). The conventional approach…
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Programmers often need to write integers as characters. Thus given the 32-bit value 1234, you might need a function that writes the characters 1234. We can use the fact that the ASCII numeral characters are in sequence in the ASCII table: ‘0’+0 is ‘0’, ‘0’+1 is ‘1’ and so forth.…
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Science and Technology links (May 15th 2021)
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There were rainforests near the south pole 90 million years ago. Though commercial exchanges are typically win-win for both the buyer and the seller, people tend to view the buyer as more likely to be taken advantage of. People with low self-esteem are more likely to blame the political system for…
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It is not uncommon that we need to represent an array of Boolean (true or false) values. There are multiple ways to do it. The most natural way could be to construct an array of booleans (the native Java type). It is likely that when stored in an array, Java uses a byte per value. boolean[] array =…
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Growing your own food could lower your carbon footprint by 3-5%. In recent years, we have acquired the ability to measure biological age: your chronological age does not necessarily match your biological since some people age faster. We measure biological aging with gene expression. Researchers…
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The division instruction is one of the most expensive instruction in your CPU. Thus optimizing compilers often compile divisions by known constants down to a multiplication followed by a shift. However, in some lucky cases, the compiler does not even need a shift. I call the corresponding divisors…