Can we make a better refrigerator?

The Scientific American article A Simple Twist of Thermodynamics Could Lead to Greener Refrigeration by Sophie Bushwick (1/21/2020) reports about the Science paper Torsional refrigeration by twisted, coiled, and supercoiled fibers by Run Wang et. el. (10/11/2019), which is behind a paywall (the graph here is from that paper). From the Scientific American article:

For another example, picture a rubber band, which is made up of a bundle of fibers. In the early 19th century, researchers found that pulling one makes it feel warmer. This effect happens because stretching the rubber band aligns the fibers more neatly, with less disorder. For this decrease in entropy to occur, the object has to pull in energy, in the form of heat, from its surroundings. When the tension is released, the entropy increases again, and the band cools down.

From the abstract of the Science paper:

Refrigerators using entropy changes during cycles of stretching or hydrostatic compression of a solid are possible alternatives to the vapor-compression fridges found in homes. We show that high cooling results from twist changes for twisted, coiled, or supercoiled fibers, including those of natural rubber, nickel titanium, and polyethylene fishing line.

The Scientific American article has a couple of interesting animations. The Science paper is technical. I’m not sure how to use any of this in a math classroom. I’m posting this because it is really interesting.

Looking for Climate Curriculum Materials?

If you are looking for teaching tools or lessons plans related to climate change then check out TROP ICSU.

The TROP ICSU project collects and curates educational resources for teachers and self-learners to learn about Climate Change. The quality of life of future generations is largely dependent on the quality of education that we impart to today’s students.

The goal is not to introduce Climate Education as a stand-alone topic, but to integrate it with the core curriculum of Science, Mathematics, and Social Sciences.

The photo here is a snapshot of their lesson plans page.

How has child mortality changed?

The article in Nature, Mapping 123 million neonatal, infant, and child deaths between 2000 and 2017, by Burstein et. el (10/16/2019), provides a detailed analysis of under 5 child mortality (U5mr).

The goal of mortality-reduction efforts is ultimately to prevent premature deaths, and not just to reduce mortality rates. Across the countries studied here, there were 3.5 million (41%) fewer deaths of children under 5 in 2017 than in 2000 (5.0 million compared to 8.5 million). At the national level, the largest number of child deaths in 2017 occurred in India (1.04 (0.98–1.10) million), Nigeria (0.79 (0.65–0.96) million), Pakistan (0.34 (0.27–0.41) million) and the Democratic Republic of the Congo (0.25 (0.21–0.31) million) (Fig. 3a).

The main article has four figure, but the supplementary materials contain another ~50 graphs, many of them spatial.

What are American’s view on economic inequality?

The PEW article Most Americans Say There Is Too Much Economic Inequality in the U.S., but Fewer Than Half Call it a Top Priority by Juliana Menasce Horowitz, Ruth Igielnik, and Rakesh Kochhar (1/9/2020)  is a thorough review of income and wealth inequality, as well as American’s views of inequality.  For example, the graph copied here shows the responses to if there is too much economic inequality by political affiliation.  A few highlights from the article:

From 1970 to 2018, the share of aggregate income going to middle-class households fell from 62% to 43%. Over the same period, the share held by upper-income households increased from 29% to 48%. The share flowing to lower-income households inched down from 10% in 1970 to 9% in 2018.

As of 2016, the latest year for which data are available, the typical American family had a net worth of $101,800, still less than what it held in 1998.

While a majority of Republicans overall (60%) say that people’s different choices in life contribute a great deal to economic inequality, lower-income Republicans (46%) are significantly less likely than Republicans with middle (63%) or higher (74%) incomes to say this.

There are numerous graphs in the article and a methodology section which points to the data sources.

What are EPI’s top charts of 2019?

To find the top charts of 2019 according to EPI see their Top charts of 2019 post.  The graph here is #5 on their list.

The figure shows that the real value of the federal minimum wage has dropped 17% since 2009 and 31% since 1968. A full-time worker earning the federal minimum wage today has about $6,800 less per year to spend on food, rent, and other essentials than did his or her counterpart 50 years ago.

There are 13 charts in all with data and links to the original article (for some charts you have to go to the original article to get the data).

 

How much does Greenland melting contribute to sea level rise?

From NASA’s Greenland’s Rapid Melt Will Mean More Flooging (12/10/2019):

Increasing rates of global warming have accelerated Greenland’s ice mass loss from 25 billion tons per year in the 1990s to a current average of 234 billion tons per year. This means that Greenland’s ice is melting on average seven times faster today than it was at the beginning of the study period. The Greenland Ice Sheet holds enough water to raise the sea level by 24 feet (7.4 meters).

The graph here is a frame from a short video on the page that is worth watching.  The data for this graph does not seem to be easily available, but data on the melting of Greenland is available at NASA’s Vital Sings Ice Sheets page.

How much has sea level risen?

The Climate.gov post Climate Change: Global Sea Level by Rebecca Lindsey (11/19/2019) notes:

Global mean sea level has risen about 8–9 inches (21–24 centimeters) since 1880, with about a third of that coming in just the last two and a half decades. The rising water level is mostly due to a combination of meltwater from glaciers and ice sheets and thermal expansion of seawater as it warms. In 2018, global mean sea level was 3.2 inches (8.1 centimeters) above the 1993 average—the highest annual average in the satellite record (1993-present)

There are other graphs and information in the post. For example, What’s causing sea level to rise?

Global warming is causing global mean sea level to rise in two ways. First, glaciers and ice sheets worldwide are melting and adding water to the ocean. Second, the volume of the ocean is expanding as the water warms. A third, much smaller contributor to sea level rise is a decline in the amount of liquid water on land—aquifers, lakes and reservoirs, rivers, soil moisture. This shift of liquid water from land to ocean is largely due to groundwater pumping.

There are links to data at the end of the post and NOAA also has sea level data that is accessible.

How hot was Australia in 2019?

The graph here is from the Australian Bureau of Meteorology Climate changes – trends and extremes page.  In 2019, the temperature was 1.52 deg C (2.7 deg F) above the 30 year average from 1961-1990, which is a new record. The second highest year is 2013 at  1.33 deg C above the average. The data is available on the page (there is a link in the box above the graph) and other attributes can be plotted. For instance, the maximum temperature for 2019 was 2.09 deg C (3.76 deg F) above the 30 year average, which is a new record with the second highest in 2013 at 1.59 deg C above the average.

How hot was November 2019?

From the NOAA Global Climate Report – November 2019:

The November 2019 global land and ocean surface temperature was 0.92°C (1.66°F) above average and the second highest November temperature in the 140-year record. Only November 2015 was warmer at +1.01°C (+1.82°F). The five warmest November global land and ocean surface temperature departures from average have occurred since 2013.

The Data can be obtained from the Climate at a Glance page.

What has improved (and not) between rich and poor countries?

The St. Louis Fed post, Healthier Countries, if Not Wealthier Countries by Guillaume Vandenbroucke (12/26/2019) notes

The income gap between rich and poor countries doesn’t seem to be closing. In fact, it seems to be getting wider. However, the gaps between these groups of countries when it comes to health may indeed be narrowing.

For example, the graph copied here provides time series of GDP of high-income countries and Sub-Saharan African countries. The gap between the two cohorts has grown. Yet,

Not surprisingly, sub-Saharan African countries exhibit a lower life expectancy at birth and a higher crude death rate than the high-income countries. What is surprising, however, is that these measures of health are converging to that of the rich countries, unlike GDP per capita.

There are two other graphs in the post. The data is from the world bank and can be found.