yair/food_energy_paper
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

apa

Browse Source
This commit is contained in:
Nathan Moore 2023-02-08 10:44:02 -06:00
parent 13e9112a71
commit acd40a3b7a
4 changed files with 90 additions and 109 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

BIN
J_Coll_Sci_Teach_submission/food_energy.pdf
View File

Binary file not shown.

BIN
J_Coll_Sci_Teach_submission/food_energy.synctex.gz
View File

Binary file not shown.

199
J_Coll_Sci_Teach_submission/food_energy.tex
View File

@ -1,6 +1,6 @@
% formatted for IOP % formatted for IOP
%\documentclass[12pt,man]{apa7} %\documentclass[12pt,man]{apa7}
\documentclass[jou]{apa7} \documentclass[man]{apa7}
\usepackage{amsmath} % needed for \tfrac, \bmatrix, etc. \usepackage{amsmath} % needed for \tfrac, \bmatrix, etc.
\usepackage{amsfonts} % needed for bold Greek, Fraktur, and blackboard bold \usepackage{amsfonts} % needed for bold Greek, Fraktur, and blackboard bold
\usepackage{graphicx} % needed for figures \usepackage{graphicx} % needed for figures
@ -25,7 +25,7 @@
\shorttitle{How Many Potatoes?} \shorttitle{How Many Potatoes?}
\leftheader{Moore} \leftheader{Moore}
%IOP header %IOP header
\title{How many acres of potatoes does a society need? Introducing Energy with Food and Historical Claims.} \title{How many acres of potatoes does a society need? Using food and historical claims to introduce energy.}
\author{Nathan T. Moore} \author{Nathan T. Moore}
\affiliation{Department of Physics, Winona State University, Winona, MN 55987, USA} \affiliation{Department of Physics, Winona State University, Winona, MN 55987, USA}
%\email{nmoore@winona.edu} %\email{nmoore@winona.edu}
@ -40,7 +40,7 @@ Science and Social Policy classes are full of bespoke units and involve many dif
\maketitle \maketitle
\section{Introduction} \section{Introduction}
When the United States entered World War One one of the problems they faced was logistics. How much food do you need to ship overseas to Europe to feed a million soldiers? That early work in nutrition led to the $3000$ Calorie diet many people remember from secondary Health Education class. A bit about ``Calorie'' (uppercase) vs ``calorie'' (lowercase) units you might remember: $1~Calorie = 1~kilocalorie~(kcal)$, and a dietitian might build a $3000 kcal$ diet for a 20 year old basketball player. A \textit{calorie} is the amount of energy it takes to heat a gram of water by a degree Celsius. There are about $4.2$ Joules in a single calorie, and a Joule occurs all over introductory physics. If you need to buy a new home furnace, the sales brochure might advertise that it is capable of delivering $100,000$ BTU's of heat each hour. What's a BTU? Heat a pound of water by $1^{\circ}F$. Of course Heat Pumps are far more efficient than simply burning methane or propane, but they consume kilo-watt-hours (kWh) of electricity, not BTU's. What's a kWh? Run a $1000$ Watt toaster for an hour and you'll have pulled one kWh off the grid, it will cost you about $\$0.13$ in Minnesota. If you decide to put solar panels in your backyard, they will probably collect about $10\%$ of the $3.5kWh$ the the sun delivers to each square meter of your lawn (in Minnesota) each day. When the United States entered World War One one of the problems they faced was logistics. How much food do you need to ship overseas to Europe to feed a million soldiers? That early work in nutrition led to the $3000$ Calorie diet many people remember from secondary Health Education class. A bit about ``Calorie'' (uppercase) vs ``calorie'' (lowercase) units you might remember: $1~Calorie = 1~kilocalorie=1 kcal$, and a dietitian might build a $3000 kcal$ diet for a 20 year old basketball player. $One~ calorie = 0.001kcal$, the amount of energy it takes to heat a gram of water by a degree Celsius. There are about $4.2$ Joules in a single calorie, and a Joule occurs all over introductory physics. If you need to buy a new home furnace, the sales brochure might advertise that it is capable of delivering $100,000$ BTU's of heat each hour. What's a BTU? Heat a pound of water by $1^{\circ}F$. Of course Heat Pumps are far more efficient than simply burning methane or propane, but they consume kilo-watt-hours (kWh) of electricity, not BTU's. What's a kWh? Run a $1000$ Watt toaster for an hour and you'll have pulled one kWh off the grid, it will cost you about $\$0.13$ in Minnesota. If you decide to put solar panels in your backyard, they will probably collect about $10\%$ of the $3.5kWh$ the the sun delivers to each square meter of your lawn (in Minnesota) each day.
As the previous paragraph illustrates, there are a frustratingly large number of different units in an ``Energy'' class. At Winona As the previous paragraph illustrates, there are a frustratingly large number of different units in an ``Energy'' class. At Winona
State, this 3 credit class fulfills a ``Science and Social Policy'' general education requirement and is taken by students from across the university. Lots of college majors don't require a math class beyond algebra or introductory statistics and the population is largely math-averse. You could jokingly say that one of the main things students learn in the class is unit conversion, but it isn't far off. Nearly every field finds energy a useful representation, and every profession has their own set of units and terminology most well suited for quick calculation. Would a medical lab scientist talk about the fractional acre-foot of urine needed test kidney function? No, but someone in the central valley of California would certainly care about the acre-feet of water necessary to grow almonds! Does a gas station price their gasoline in dollars per kWh? Given the growing electrification of cars, they might soon. State, this 3 credit class fulfills a ``Science and Social Policy'' general education requirement and is taken by students from across the university. Lots of college majors don't require a math class beyond algebra or introductory statistics and the population is largely math-averse. You could jokingly say that one of the main things students learn in the class is unit conversion, but it isn't far off. Nearly every field finds energy a useful representation, and every profession has their own set of units and terminology most well suited for quick calculation. Would a medical lab scientist talk about the fractional acre-foot of urine needed test kidney function? No, but someone in the central valley of California would certainly care about the acre-feet of water necessary to grow almonds! Does a gas station price their gasoline in dollars per kWh? Given the growing electrification of cars, they might soon.
@ -75,7 +75,6 @@ equate food energy with calorimetric heating and assume human bodies have the sa
\eea \eea
Students are normally quite surprised at this number. Although wildly unrealistic, $\Delta T \approx +6\degC$ is typically fatal, there is a related phenomena of diet-induced thermogenesis, Students are normally quite surprised at this number. Although wildly unrealistic, $\Delta T \approx +6\degC$ is typically fatal, there is a related phenomena of diet-induced thermogenesis,
(Caballero, 2003, pp. 5762-7.) (Caballero, 2003, pp. 5762-7.)
%\cite{meat_sweats}
known informally as ``the meat sweats''. Some students connect this calculation to feeling quite hungry after a cold swim in the pool (a similar effect). On a larger scale, discussing what's wrong with this estimate is useful. The main storage mechanism for storing food energy is fat tissue, which the calculation completely ignores. Infants are generally born with little fat, and an infant sleeping through the night often coincides with the baby developing enough fat tissue to store sufficient kcals to make it though a night without waking up ravenously hungry. A related follow-up is that if a person is stranded in the wilderness, they should immediately start walking downstream (ie, towards civilization) as they likely won't be able to harvest an amount of kcals equivalent to what they already have stored on their hips and abdomen. (USDA ARS, 2019) The contrast of bear hibernation, (North American Bear Center, 2023), and songbirds constantly eating through the winter are related connections to investigate. known informally as ``the meat sweats''. Some students connect this calculation to feeling quite hungry after a cold swim in the pool (a similar effect). On a larger scale, discussing what's wrong with this estimate is useful. The main storage mechanism for storing food energy is fat tissue, which the calculation completely ignores. Infants are generally born with little fat, and an infant sleeping through the night often coincides with the baby developing enough fat tissue to store sufficient kcals to make it though a night without waking up ravenously hungry. A related follow-up is that if a person is stranded in the wilderness, they should immediately start walking downstream (ie, towards civilization) as they likely won't be able to harvest an amount of kcals equivalent to what they already have stored on their hips and abdomen. (USDA ARS, 2019) The contrast of bear hibernation, (North American Bear Center, 2023), and songbirds constantly eating through the winter are related connections to investigate.
\subsection{Biophysical Power} \subsection{Biophysical Power}
@ -90,7 +89,6 @@ Another application to discuss is that of ``brown fat,'' a sort of biological sp
Cohen \& Spiegelman, 2015; Cohen \& Spiegelman, 2015;
Himms-Hagen, 1984; Himms-Hagen, 1984;
Shamsi et al., 2021) Shamsi et al., 2021)
\cite{,brown_fat_2,brown_fat_3,}
Most common in rodents and infants, this mechanism can be stimulated by extended exposure to cold temperatures -- the original work was done on lumberjacks in Finland. Most common in rodents and infants, this mechanism can be stimulated by extended exposure to cold temperatures -- the original work was done on lumberjacks in Finland.
(Huttunen et al., 1981) (Huttunen et al., 1981)
The idea of a biological space heater that takes a month to turn on and a month to turn off matches the lived experience of college students in Minnesota, who wear down jackets in $4\degC$ weather in November, and beachwear in the same $4\degC$ weather in March. Additionally, transplants to northern climates often take a few years to ``get used to'' the colder weather up north. It seems just as easy to say that transplants' bodies take a few years to develop the brown fat cells which allow them to be comfortable in cold weather. The idea of a biological space heater that takes a month to turn on and a month to turn off matches the lived experience of college students in Minnesota, who wear down jackets in $4\degC$ weather in November, and beachwear in the same $4\degC$ weather in March. Additionally, transplants to northern climates often take a few years to ``get used to'' the colder weather up north. It seems just as easy to say that transplants' bodies take a few years to develop the brown fat cells which allow them to be comfortable in cold weather.
@ -98,7 +96,7 @@ The idea of a biological space heater that takes a month to turn on and a month
One other distinction to emphasize is the difference between power and energy. A graph of a human body's ``kcal content'' over the course of a day can be a useful illustration. When sedentary, this graph probably has the slope of $-150W\approx -125 \frac{kcals}{hour}$. If the $3000kcal$ meal at the buffet takes an hour, this period corresponds to an energy-time slope of One other distinction to emphasize is the difference between power and energy. A graph of a human body's ``kcal content'' over the course of a day can be a useful illustration. When sedentary, this graph probably has the slope of $-150W\approx -125 \frac{kcals}{hour}$. If the $3000kcal$ meal at the buffet takes an hour, this period corresponds to an energy-time slope of
$+3000\frac{kcal}{hour}\approx +3500W$. $+3000\frac{kcal}{hour}\approx +3500W$.
In medicine, these slopes are effectively equivalent to ``Metabolic Equivalent of Task'' (METS), a common measure in cardiology and exercise physiology. METS is power normalized by mass, $1METS=1\frac{kcal}{kg\cdot hour}$, and METS levels are available for many different physical activities. (Jetté \& Blümchen , 1990) In medicine, these slopes known as ``Metabolic Equivalent of Task'' (METS), a common measure in cardiology and exercise physiology. METS is power normalized by mass, $1METS=1\frac{kcal}{kg\cdot hour}$, and METS levels are available for many different physical activities. (Jetté \& Blümchen, 1990) For example, doing the dishes is $2.1METS$, folkdancing is $4.8METS$, and the fun part of human reproduction reportedly ranks at $5.8METS$. (Frappier et al., 2013)
\subsection{Burning off food energy} \subsection{Burning off food energy}
Imagine that after eating a $600kcal$ bacon-maple long-john (donut), you decide to go for a hike to ``work off'' the Calories. Imagine that after eating a $600kcal$ bacon-maple long-john (donut), you decide to go for a hike to ``work off'' the Calories.
@ -116,7 +114,6 @@ Useful information: human muscle is about $1/3$ efficient, and on Earth's surfac
One way to approach this problem is by using Energy Bar Charts (Brewe, 2011) to illustrate how the energy held in food changes form as it is used. An approximation for this question is shown in figure \ref{bar_chart}. One way to approach this problem is by using Energy Bar Charts (Brewe, 2011) to illustrate how the energy held in food changes form as it is used. An approximation for this question is shown in figure \ref{bar_chart}.
In this story, the ``system'' is taken to be the earth, food, and hiker. The hiker's body is assumed to be $1/3$ efficient, which means one of the food energy blocks of energy is transformed into gravitational energy (elevation) at the end of the hike. In this story, the ``system'' is taken to be the earth, food, and hiker. The hiker's body is assumed to be $1/3$ efficient, which means one of the food energy blocks of energy is transformed into gravitational energy (elevation) at the end of the hike.
The other $2$ blocks of energy are transformed into heat and leave the hiker's body, most likely by mechanisms of respiration and sweat evaporation. The purpose of a bar chart like this is to provide a pictorial and mathematical representation of the energy conservation equation given in \ref{eq:bar_chart}. The other $2$ blocks of energy are transformed into heat and leave the hiker's body, most likely by mechanisms of respiration and sweat evaporation. The purpose of a bar chart like this is to provide a pictorial and mathematical representation of the energy conservation equation given in \ref{eq:bar_chart}.
\bea \bea
\frac{1}{3}\cdot600kcal\cdot\frac{4200J}{1kcal} \frac{1}{3}\cdot600kcal\cdot\frac{4200J}{1kcal}
&=& 80kg\cdot10\frac{Joules}{kg\cdot m}\cdot height , \label{eq:bar_chart}\\ &=& 80kg\cdot10\frac{Joules}{kg\cdot m}\cdot height , \label{eq:bar_chart}\\
@ -129,9 +126,9 @@ The point of these energy calculations is not to give students an eating disorde
%\clearpage %\clearpage
\subsection{Where does food energy come from?} \subsection{Where does food energy come from?}
One feature of the aught's ``homesteading'' culture One feature of the aught's ``homesteading'' culture\footnote{
\footnote{See for example, the Discover television show, ``Alaska the Last Frontier,'' any issue of ``Mother Earth News,'' or Backyard Chicken feeds on Instagram. } See for example, the Discover television show, ``Alaska the Last Frontier,'' any issue of ``Mother Earth News,'' or Backyard Chicken feeds on Instagram.
%\cite{homesteading} }
is the idea that a person should probably be able to move to the country, eat a lot of peaches, and grow all their own food. Learning that farming labor is \textit{skilled} labor can be brutal and disheartening. Eating $3000kcals$ each day means planting, weeding, harvesting, and storing more than a million kcals each year. (Haspel, 2015) is the idea that a person should probably be able to move to the country, eat a lot of peaches, and grow all their own food. Learning that farming labor is \textit{skilled} labor can be brutal and disheartening. Eating $3000kcals$ each day means planting, weeding, harvesting, and storing more than a million kcals each year. (Haspel, 2015)
Where will those Calories come from? Is your backyard enough to homestead in the suburbs?(Madigan, 2009) Where will those Calories come from? Is your backyard enough to homestead in the suburbs?(Madigan, 2009)
@ -156,12 +153,11 @@ USDA per acre crop production figures, plotted over time. Production data is sc
Details of the data source and conversions are given in \ref{how_yield_plot_is_made}. Details of the data source and conversions are given in \ref{how_yield_plot_is_made}.
The idea for this plot came from an online blog. (Biegert, 2017) The idea for this plot came from an online blog. (Biegert, 2017)
It would be interesting to know if there are patterns of scaling among vegetable families (grains, legumes, tubers, etc) in the same way that there are family classifications for the minimal energy required for transport. (Tucker, 1975) It would be interesting to know if there are patterns of scaling among vegetable families (grains, legumes, tubers, etc) in the same way that there are family classifications for the minimal energy required for transport. (Tucker, 1975)
%\cite{energetic_cost_of_moving}
} }
\label{ag_yields} \label{ag_yields}
\end{figure} \end{figure}
However, if you're discussing backyard Calorie production it isn't reasonable to use modern yield estimates for planning. ``Roundup Ready'' Corn, Soybean, and Sugar Beet seeds are not available to the public, nobody wants to put on a respirator to apply Atrazine ten feet from the back door, and the edge effects from deer and insects are much smaller on a $600$ acre field than they are in an community garden allotment. As mentioned in the introduction, in 1917 the USDA published a pamphlet (Cooper, 1917) giving detailed Calorie estimates a farmer might expect from a given acre of a crop. A table from this pamphlet is shown in Figure \ref{1917_yields}. However, if you're discussing backyard Calorie production it isn't reasonable to use modern yield estimates for planning. ``Roundup Ready'' Corn, Soybean, and Sugar Beet seeds are not available to the public, nobody wants to put on a respirator to apply Atrazine ten feet from the back door, and the edge effects from deer and insects are much smaller on a $600$ acre field than they are in an community garden allotment. As mentioned in the introduction, in 1917 the USDA published a pamphlet (Cooper \& Spillman, 1917) giving detailed Calorie estimates a farmer might expect from a given acre of a crop. A table from this pamphlet is shown in Figure \ref{1917_yields}.
The pamphlet data came from pre-war, pre-chemical agriculture, and the yields cited were produced with horses, manure, lime, and large families full of children. If you want to be self sufficient, these yield numbers are probably a good upper bound on what's realistically possible by a dedicated Luddite. The pamphlet data came from pre-war, pre-chemical agriculture, and the yields cited were produced with horses, manure, lime, and large families full of children. If you want to be self sufficient, these yield numbers are probably a good upper bound on what's realistically possible by a dedicated Luddite.
\begin{figure}[ht!] \begin{figure}[ht!]
@ -178,7 +174,6 @@ So, another question using this data. If you want to feed your family of four p
Here's an estimate: a family of 4 requires $3000kcal/person$ each day.\footnote{ Here's an estimate: a family of 4 requires $3000kcal/person$ each day.\footnote{
Is $3000\frac{kcal}{person\cdot day}$ accurate for a family? For soldiers or active athletes it is, but $2000kcal$ is the USDA reference for an ``average adult,'' e.g. the author, in his 40's, and $1000-1200kcal$ for a senior age ($>60$) female. However, weeding the garden all day is physically taxing, mice will probably eat some of the potatoes, and $3000$ is a nice round number, so that's what I'm using. Is $3000\frac{kcal}{person\cdot day}$ accurate for a family? For soldiers or active athletes it is, but $2000kcal$ is the USDA reference for an ``average adult,'' e.g. the author, in his 40's, and $1000-1200kcal$ for a senior age ($>60$) female. However, weeding the garden all day is physically taxing, mice will probably eat some of the potatoes, and $3000$ is a nice round number, so that's what I'm using.
} }
%\cite{calorie_age}
If we over-estimate and produce food for the entire year, the family will need about $4.4$ million kcals. If we over-estimate and produce food for the entire year, the family will need about $4.4$ million kcals.
\be \be
4~people\cdot\frac{3000kcal}{person\cdot day}\cdot\frac{365~days}{year} \approx 4.4 M kcal . 4~people\cdot\frac{3000kcal}{person\cdot day}\cdot\frac{365~days}{year} \approx 4.4 M kcal .
@ -209,10 +204,9 @@ Each crop has its own custom units, for example potatoes are sold by hundredweig
Every imaginable agricultural product seems to be tracked in the NASS site, for example Maple Syrup production is tracked and given in gallons of syrup per tap! Every imaginable agricultural product seems to be tracked in the NASS site, for example Maple Syrup production is tracked and given in gallons of syrup per tap!
Conversion factors used are summarized in Table \ref{conversions}. Conversion factors used are summarized in Table \ref{conversions}.
Calorie (kcal) density for each crop was taken from the USDA's Food Data Central.(USDA ARS, 2023) Calorie (kcal) density for each crop was taken from the USDA's Food Data Central.(USDA ARS, 2023)
%\cite{USDA_FDC}
Within this database, foods are identified by an FDC ID. Within this database, foods are identified by an FDC ID.
An example calculation (implemented in the Jupyter notebook) follows for Corn. An example calculation (implemented in a Jupyter notebook) follows for Corn.
In 2022 the USDA reported an average production of $172.3$ bushels of corn per acre of farmland. In 2022 the USDA reported an average production of $172.3$ bushels of corn per acre of farmland.
\be \be
172.3\frac{bu}{acre}\cdot\frac{56lbs~corn}{bu}\cdot\frac{453.6~grams}{lbs}\cdot\frac{365~kcal}{100~grams} = 15,974,657 \frac{kcal}{acre} . 172.3\frac{bu}{acre}\cdot\frac{56lbs~corn}{bu}\cdot\frac{453.6~grams}{lbs}\cdot\frac{365~kcal}{100~grams} = 15,974,657 \frac{kcal}{acre} .
@ -261,25 +255,23 @@ Average USDA per acre yields for a number of commodity crops over time. This ``
\section{Example: How big could Tenochtitlan have been?} \section{Example: How big could Tenochtitlan have been?}
The questions described thus far have largely been centered within a physics context. The paper closes with two more examples that leverage this food energy picture to make historical claims. The first example relates to the pre-Colombian capital of the Aztec Empire, Tenochtitlan, now known as Mexico City. Tenochtitlan was built on and around a endorheic lake, Texcoco. Crops were grown in shallow parts of the lake via chinampas, (Borunda \& Rodriguez, 2022) floating patches of decaying vegetation and soil. Given the proximity to water and decaying vegetation, these fields were very fertile (Coe, 1964; Ebel, 2019) and some continue to be used in the present day.\footnote{Chinampas are still visible in sattelite imagery. See for example $latitude=19.268$, $longitude=-99.087$.} The questions described thus far have largely been centered within a physics context. The paper closes with two more examples that leverage this food energy picture to make historical claims. The first example relates to the pre-Colombian capital of the Aztec Empire, Tenochtitlan, now known as Mexico City. Tenochtitlan was built on and around a endorheic lake, Texcoco. Crops were grown in shallow parts of the lake via chinampas, (Borunda \& Rodriguez, 2022) floating patches of decaying vegetation and soil. Given the proximity to water and decaying vegetation, these fields were very fertile (Coe, 1964; Ebel, 2019) and some continue to be used in the present day.\footnote{
%\cite{google_earth} Chinampas are still visible in sattelite imagery. See for example $latitude=19.268$, $longitude=-99.087$.
}
Estimates of Tenochtitlan's population in 1500CE vary widely, from 40,000 Estimates of Tenochtitlan's population in 1500CE vary widely, from 40,000
%\cite{40k} (Evans, 2013, p549)
(Evans, 2013 p549)
to more than 400,000 inhabitants (Britannica, 2022), comparable in size to Paris at that time. These estimates come from oral and written records and estimates of archaeological building density and land area. While cannibalism was part of Aztec religious ritual and practice, to more than 400,000 inhabitants (Britannica, 2022), comparable in size to Paris at that time. These estimates come from oral and written records and estimates of archaeological building density and land area. While cannibalism was part of Aztec religious ritual and practice,
(Ortiz de Montellano, 1978), the staple Calorie sources for the Aztecs were corn and beans. (Ortiz de Montellano, 1978), the staple Calorie sources for the Aztecs were corn and beans.
Few if any Native American cultures made use of draft animals for food or power before the Colombian Exchange. This means that the food that fed Tenochtitlan must have been brought to the city center by foot or canoe. How much land must have been devoted to chinampas to feed the population, or conversely, how many people could be supported by the land within walking or paddling distance from the city center? Few if any Native American cultures made use of draft animals for food or power before the Colombian Exchange. This means that the food that fed Tenochtitlan must have been brought to the city center by foot or canoe. How much land must have been devoted to chinampas to feed the population, or conversely, how many people could be supported by the land within walking or paddling distance from the city center?
A 1964 paper in Scientific American (Coe, 1964) gives a general outline of the chinampas in the area of Tenochtitlan in 1500CE. This map seems to be the basis for the similar figure in Wikipedia. (File:Lake Texcoco c 1519.png, 2016) A 1964 paper in Scientific American (Coe, 1964) gives a general outline of the chinampas in the area of Tenochtitlan in 1500CE. This map seems to be the basis for the similar figure in Wikipedia. (File:Lake Texcoco c 1519.png, 2016)
%\cite{chinampas_wikipedia}
Descriptions of chinampas agriculture indicate that as many as $7$ successive crops could be grown and harvested from the same plot of soil each year, two of which could be maize (corn). This is truly amazing productivity, given that in the midwest United States corn is normally grown, at most, every other year because of its extreme nutrient demands on the soil. Descriptions of chinampas agriculture indicate that as many as $7$ successive crops could be grown and harvested from the same plot of soil each year, two of which could be maize (corn). This is truly amazing productivity, given that in the midwest United States corn is normally grown, at most, every other year because of its extreme nutrient demands on the soil.
There are many ways to approach this estimation problem. We could assume a Tenochtitlan population of $100,000$ people has a $3000kcal/day$ diet that comes completely from corn. Assuming that corn's density and nutritional content haven't changed in the $4$ centuries preceding the 1917 data in figure \ref{1917_yields}, we could assume $1lbs$ of corn contains $\approx1594kcal$ of food energy. There are many ways to approach this estimation problem. We could assume a Tenochtitlan population of $100,000$ people has a $3000kcal/day$ diet that comes completely from corn. Assuming that corn's density and nutritional content haven't changed in the $4$ centuries preceding the 1917 data in figure \ref{1917_yields}, we could assume $1lbs$ of corn contains $\approx1594kcal$ of food energy.
Looking at the map with ImageJ, (Schneider et al., 2012) it seems like the recorded area devoted to chinampas might be about Looking at the map with ImageJ, (Schneider et al., 2012) it seems like the recorded area devoted to chinampas might be about $16,000~acres$.
$16,000~acres$ -- details are given in \ref{appx_imageJ}.
With these assumptions, we could equate the corn energy production from chinampas with the population's yearly food need. Note, in this version of the story, the corn productivity, $P\frac{bu}{acre}$ is treated as an unknown variable. With these assumptions, we could equate the corn energy production from chinampas with the population's yearly food need. Note, in this version of the story, the corn productivity, $P\frac{bu}{acre}$ is treated as an unknown variable.
\bea \bea
Food~production &=& 16,000acres\cdot \frac{2~corn~crops}{year}\cdot P \frac{bu~of~corn}{acre} . \\ Food~production &=& 16,000acres\cdot \frac{2~corn~crops}{year}\cdot P \frac{bu~of~corn}{acre} . \\
@ -292,7 +284,7 @@ This crop productivity is in remarkable agreement with the 1917 USDA yields, $35
\subsection{Estimating land area devoted to chinampas with ImageJ} \subsection{Estimating land area devoted to chinampas with ImageJ}
\label{appx_imageJ} \label{appx_imageJ}
ImageJ is a free software program developed by the National Institutes of Health for photo analysis. (Schneider et al., 2012) I used the program to measure a calibration scale in a map and I also used the program to measure the area of two polygons that I drew on the map. Both areas and the calibration length are shown in figure \ref{imageJ}. ImageJ is a free software program developed by the National Institutes of Health for photo analysis. (Schneider et al., 2012) I used the program to measure a calibration scale in a map and the area of two polygons that I drew on the map. Both areas and the calibration length are shown in figure \ref{imageJ}.
Specifically, to find the area of the two large chinampas areas near Tenochtitlan, I took a screenshot from the 1964 paper (Coe, 1964) and saved it in jpg format. Then, I opened the image in the Windows-Java edition of ImageJ. The length of the 10 mile distance scale was 213 pixels. The long chinampas area at the south end of the lake was measured with a Polygon selection via the Measure tool to have an area of $9940~pixel^2\approx21.9miles^2$. The smaller region near Chalco had an area of about $1439~pixel^2\approx3.2miles^2$. While there were certainly other regions devoted to chimanpas agriculture, the portion visible near the Aztec capital seems to be about $25.1miles^2$ or $16,000acres$. Specifically, to find the area of the two large chinampas areas near Tenochtitlan, I took a screenshot from the 1964 paper (Coe, 1964) and saved it in jpg format. Then, I opened the image in the Windows-Java edition of ImageJ. The length of the 10 mile distance scale was 213 pixels. The long chinampas area at the south end of the lake was measured with a Polygon selection via the Measure tool to have an area of $9940~pixel^2\approx21.9miles^2$. The smaller region near Chalco had an area of about $1439~pixel^2\approx3.2miles^2$. While there were certainly other regions devoted to chimanpas agriculture, the portion visible near the Aztec capital seems to be about $25.1miles^2$ or $16,000acres$.
@ -310,15 +302,15 @@ Three screen captures showing chinampa areas and the calibration stick used to c
\section{Example: Was the Irish Potato Famine a Natural Disaster?} \section{Example: Was the Irish Potato Famine a Natural Disaster?}
In contrast to native cultures of the Americas, Ireland's population boomed with the Colombian Exchange and the introduction of the potato. (Fagan, 2001; Salaman \& Hawkes, 1985) In contrast to native cultures of the Americas, Ireland's population boomed with the Colombian Exchange and the introduction of the potato. (Fagan, 2001; Salaman \& Hawkes, 1985)
Figure \ref{ireland_population} shows that from about 1700 onward there was a dramatic growth in the island's population. There's never just one reason for historical events, but unlike grains, potatoes thrived in Ireland's cool damp climate and potatoes, kale, and milk form a nutritionally complete diet that greatly reduced hunger-related mortality among the poor working-class in Ireland. If you look closely at the data in figure \ref{ireland_population} you might believe that there were \textit{two} weather and potato related famines, the most obvious 1845-49 and the second, with much smaller effect on population in 1740-1. Both famines were precipitated by poor weather, but an important difference is that in 1740, Ireland was a sovereign state but by 1845 the island was effectively an economic colony of the British Empire.\cite{little_ice_age} Figure \ref{ireland_population} shows that from about 1700 onward there was a dramatic growth in the island's population. There's never just one reason for historical events, but unlike grains, potatoes thrived in Ireland's cool damp climate. Potatoes, kale, and milk form a nutritionally complete diet that greatly reduced hunger-related mortality among the poor working-class in Ireland. If you look closely at the data in figure \ref{ireland_population} you might believe that there were \textit{two} weather and potato related famines, the most obvious 1845-49 and the second, with much smaller effect on population in 1740-1. Both famines were precipitated by poor weather, but an important difference is that in 1740, Ireland was a sovereign state but by 1845 the island was effectively an economic colony of the British Empire. (Fagan, 2001)
As the story goes, the two main commodity crops in Ireland were potatoes (for humans), and oats, which as horse feed, were something like gasoline in today's economy. A sovereign government can halt the export of food to feed English horses, which is what happened in 1741 (and 1782). The grain was diverted back as relief to starving people in Ireland, reducing the famine's mortality. However, by 1845 most of Irish farmland was economically controlled by foreign (English) markets, and grain traders typically refused to divert oats (horse feed) as famine relief for the sake of their investment income. As the story goes, the two main commodity crops in Ireland were potatoes (for humans), and oats, which as horse feed, were something like gasoline in today's economy. A sovereign government can halt the export of food to feed English horses, which is what happened in 1741 (and 1782). The grain was diverted back as relief to starving people in Ireland, reducing the famine's mortality. However, by 1845 most of Irish farmland was economically controlled by foreign (English) markets, and grain traders typically refused to divert oats (horse feed) as famine relief for the sake of their investment income.
This inflammatory claim, which is certainly a simplified version of history, serves as a useful evaluation example for students. Specifically, in years that the potato crop failed because of weather or late blight, could the amount of oats produced (and exported) have fed the Irish population? More broadly, was the Great Famine due to weather and disease, natural causes ``we can't do anything about,'' or was the depth of the tragedy a result of political choices? This inflammatory claim, which is certainly a simplified version of history, serves as a useful evaluation example for students. Specifically, in years that the potato crop failed because of weather or late blight, could the amount of oats produced (and exported) have fed the Irish population? More broadly, was the Great Famine due to weather and disease, natural causes ``we can't do anything about,'' or was the depth of the tragedy a result of political choices?
Some estimates follow: Ireland's population in 1845 was about $8.5$ million people. The island has an area of about $84,400km^2$\footnote{ Some estimates follow: Ireland's population in 1845 was about $8.5$ million people. The island has an area of about $84,400km^2$\footnote{
Currently, Northern Ireland and the Republic of Ireland are separate countries. Together, their land area is about $84,400km^2$.} Currently, Northern Ireland and the Republic of Ireland are separate countries. Together, their land area is about $84,400km^2$.
%\cite{IRE_area} }
and you might estimate that $64\%$ of the land ($54,000km^2$) is arable for agriculture. (Ask about Ireland, 2023) and you might estimate that $64\%$ of the land ($54,000km^2$) is arable for agriculture. (Ask about Ireland, 2023)
It seems reasonable to use the 1917 productivity, figure \ref{1917_yields}, to make calculations for Ireland in 1845. Reminder, in 1917, potatoes produced $1.908\times10^6 kcal/acre$ and oats $1.254\times10^6kcal/acre$. It seems reasonable to use the 1917 productivity, figure \ref{1917_yields}, to make calculations for Ireland in 1845. Reminder, in 1917, potatoes produced $1.908\times10^6 kcal/acre$ and oats $1.254\times10^6kcal/acre$.
With students, evaluation of the claim could be approached as a series of questions: With students, evaluation of the claim could be approached as a series of questions:
@ -354,8 +346,6 @@ Like the Holodomor or the Great Leap Forward, the numbers suggest that large-sca
\includegraphics[width=\columnwidth]{Population_of_Ireland_since_1600.png} \includegraphics[width=\columnwidth]{Population_of_Ireland_since_1600.png}
\caption{ \caption{
The population of Ireland over time, file from Wikipedia. (File:Population of the island of Ireland since 1600.png, 2010) The population of Ireland over time, file from Wikipedia. (File:Population of the island of Ireland since 1600.png, 2010)
%\cite{pop_image}.
% data sources. \cite{pop_sources}
The humble potato, kale, and milk were part of an amazing population boom. Note that there were two weather-related ``potato'' famines in Ireland, in about 1740 and 1850. Government policy response to the famines could explain the drastic difference in subsequent population following each of the two famines. The population of Ireland finally re-reached its 1851 peak in 2021. (Carroll, 2021) The humble potato, kale, and milk were part of an amazing population boom. Note that there were two weather-related ``potato'' famines in Ireland, in about 1740 and 1850. Government policy response to the famines could explain the drastic difference in subsequent population following each of the two famines. The population of Ireland finally re-reached its 1851 peak in 2021. (Carroll, 2021)
} }
\label{ireland_population} \label{ireland_population}
@ -407,7 +397,7 @@ Borunda A. A. \& Rodriguez C. C.
(2022 Jun 30). (2022 Jun 30).
In Mexico City, the pandemic revived Aztec-era island farms. In Mexico City, the pandemic revived Aztec-era island farms.
\textit{National Geographic}. \textit{National Geographic}.
Available from \url{https://www.nationalgeographic.com/magazine/article/in-mexico-city-the-pandemic-revived-aztec-era-island-farms} \url{https://www.nationalgeographic.com/magazine/article/in-mexico-city-the-pandemic-revived-aztec-era-island-farms}
%ALEJANDRA BORUNDA A %ALEJANDRA BORUNDA A
%CÉSAR RODRÍGUEZ C %CÉSAR RODRÍGUEZ C
@ -418,12 +408,19 @@ Brewe E.
Energy as a substancelike quantity that flows: Theoretical considerations Energy as a substancelike quantity that flows: Theoretical considerations
and pedagogical consequences. and pedagogical consequences.
%Eric Brewe %Eric Brewe
Physical Review Physics Education Research, \textit{Physical Review Physics Education Research},
%PHYSICAL REVIEW SPECIAL TOPICS - PHYSICS EDUCATION RESEARCH %PHYSICAL REVIEW SPECIAL TOPICS - PHYSICS EDUCATION RESEARCH
7, 020106. 7, 020106.
https://doi.org/10.1103/PhysRevSTPER.7.020106 \url{https://doi.org/10.1103/PhysRevSTPER.7.020106}
%https://journals.aps.org/prper/abstract/10.1103/PhysRevSTPER.7.020106 %https://journals.aps.org/prper/abstract/10.1103/PhysRevSTPER.7.020106
\bibitem{400k}
%(Britannica, 2022)
Britannica.
(2022, Dec 23).
\textit{Tenochtitlán},
\url{https://www.britannica.com/place/Tenochtitlan}
\bibitem{meat_sweats} \bibitem{meat_sweats}
%https://www.bonappetit.com/story/meat-sweats %https://www.bonappetit.com/story/meat-sweats
%(Caballero, 2003) %(Caballero, 2003)
@ -431,12 +428,12 @@ Caballero B.
(2003). (2003).
Thermogenesis. Thermogenesis.
In Trayhurn P. (Ed.). In Trayhurn P. (Ed.).
Encyclopedia of Food Sciences and Nutrition (2nd ed.). \textit{Encyclopedia of Food Sciences and Nutrition (2nd ed.).}
%edited by Benjamin Caballero %edited by Benjamin Caballero
Academic Press. Academic Press.
%pp. 5762-7. %pp. 5762-7.
%ISBN 9780122270550, %ISBN 9780122270550,
https://doi.org/10.1016/B0-12-227055-X/01188-3. \url{https://doi.org/10.1016/B0-12-227055-X/01188-3}
%(https://www.sciencedirect.com/science/article/pii/B012227055X011883) %(https://www.sciencedirect.com/science/article/pii/B012227055X011883)
\bibitem{brown_fat_3} \bibitem{brown_fat_3}
@ -477,6 +474,16 @@ The Chinampas of Mexico.
%Stable URL: https://www.jstor.org/stable/10.2307/24931564 %Stable URL: https://www.jstor.org/stable/10.2307/24931564
Available online at \url{https://www.jstor.org/stable/10.2307/24931564} Available online at \url{https://www.jstor.org/stable/10.2307/24931564}
\bibitem{USDA_1917_yields_pamphlet}
%(Cooper \& Spillman, 1917)
Cooper M. O. \& Spillman W. J.
(1917 October).
Human Food from an Acre of Staple Farm Products.
\textit{Farmers' Bulletin},
877,
%Morton O. Cooper and W.J. Spillman
Government Printing Office, United States Department of Agriculture.
\url{https://handle.nal.usda.gov/10113/ORC00000242}
\bibitem{brown_fat_1} \bibitem{brown_fat_1}
%(Cohen \& Spiegelman, 2015) %(Cohen \& Spiegelman, 2015)
@ -490,7 +497,7 @@ Brown and beige fat: molecular parts of a thermogenic machine.
2346-–51. 2346-–51.
%(2015). %(2015).
%DOI: 10.2337/db15-0318 %DOI: 10.2337/db15-0318
https://doi.org/10.2337/db15-0318 \url{https://doi.org/10.2337/db15-0318}
\bibitem{organic_corn_yield} \bibitem{organic_corn_yield}
%(Delate et al., 1998) %(Delate et al., 1998)
@ -501,7 +508,7 @@ Delate K., Cambardella C., \& Burcham B.
(1998). (1998).
Comparison of Organic and Conventional Corn, Comparison of Organic and Conventional Corn,
Soybean, Alfalfa, Oats, And Rye Crops at the Neely Kinyon Long-Term Agroecological Research (LTAR) Site. Soybean, Alfalfa, Oats, And Rye Crops at the Neely Kinyon Long-Term Agroecological Research (LTAR) Site.
Available from: \url{http://extension.agron.iastate.edu/organicag/researchreports/n-kltar98.pdf} \url{http://extension.agron.iastate.edu/organicag/researchreports/n-kltar98.pdf}
%Dr. Kathleen Delate, assistant professor, Depts. of Horticulture \& Agronomy %Dr. Kathleen Delate, assistant professor, Depts. of Horticulture \& Agronomy
%Dr. Cynthia Cambardella, soil scientist, USDA National Soil Tilth Lab %Dr. Cynthia Cambardella, soil scientist, USDA National Soil Tilth Lab
%Bob Burcham, farm superintendent, Neely-Kinyon Research and Demonstration Farm %Bob Burcham, farm superintendent, Neely-Kinyon Research and Demonstration Farm
@ -510,7 +517,7 @@ Available from: \url{http://extension.agron.iastate.edu/organicag/researchreport
\bibitem{Deppe} \bibitem{Deppe}
%(Deppe, 2020) %(Deppe, 2020)
Deppe C. Deppe C.
(2020) (2020).
\textit{The 20 Potato a Day Diet versus the Nearly All Potato Winter}. \textit{The 20 Potato a Day Diet versus the Nearly All Potato Winter}.
\url{https://www.caroldeppe.com/The\%2020\%20Potato\%20a\%20Day\%20Diet.html} \url{https://www.caroldeppe.com/The\%2020\%20Potato\%20a\%20Day\%20Diet.html}
@ -523,14 +530,14 @@ Chinampas: An Urban Farming Model of the Aztecs and a Potential Solution for Mod
%Roland Ebel %Roland Ebel
%Volume/Issue: Volume 30: Issue 1 %Volume/Issue: Volume 30: Issue 1
30(1), 13--19. 30(1), 13--19.
https://doi.org/10.21273/HORTTECH04310-19 \url{https://doi.org/10.21273/HORTTECH04310-19}
\bibitem{40k} \bibitem{40k}
%Susan Toby Evans. %Susan Toby Evans.
%(Evans, 2013) %(Evans, 2013)
Evans S. T. Evans S. T.
(2013). (2013).
Ancient Mexico and Central America: Archaeology and Culture History. \textit{Ancient Mexico and Central America: Archaeology and Culture History}.
Thames \& Hudson. Thames \& Hudson.
%p 549. %p 549.
@ -542,6 +549,35 @@ Fagan B.
\textit{The Little Ice Age: How Climate Made History 1300-1850}. \textit{The Little Ice Age: How Climate Made History 1300-1850}.
Basic Books. Basic Books.
\bibitem{chinampas_wikipedia}
%(File:Lake Texcoco c 1519.png, 2016)
File:Lake Texcoco c 1519.png.
(2016, Aug 17).
In \textit{Wikipedia}.
\url{https://commons.wikimedia.org/wiki/File:Lake\_Texcoco\_c\_1519.png}
%Self-published work by Wikipedia user Madman2001
%\bibitem{IRE_area}
%Currently, Northern Ireland and the Republic of Ireland are separate countries. Together, their land area is about $84,400km^2$.
\bibitem{pop_image}
%(File:Population of the island of Ireland since 1600.png, 2010)
File:Population of the island of Ireland since 1600.png.
(2010, Jan 13)
In \textit{Wikipedia}.
\url{https://commons.wikimedia.org/wiki/File:Population\_of\_Ireland\_since\_1600.png}
Specific census data sources for the Ireland population plot are given at the ``talk'' page
\url{https://commons.wikimedia.org/wiki/File\_talk:Population\_of\_Ireland\_since\_1600.png}
\bibitem{the_fun_part}
%(Frappier et al., 2013)
Frappier, J., Toupin, I., Levy, J. J., Aubertin-Leheudre, M.,\& Karelis, A. D.
(2013).
Energy expenditure during sexual activity in young healthy couples.
\textit{PloS one}, 8(10), e79342.
\url{https://doi.org/10.1371/journal.pone.0079342}
\bibitem{Haspel} \bibitem{Haspel}
%(Haspel, 2015) %(Haspel, 2015)
Haspel T. Haspel T.
@ -561,7 +597,7 @@ Nonshivering thermogenesis.
\textit{Brain Research Bulliten}, \textit{Brain Research Bulliten},
12 (2), 12 (2),
151--60. 151--60.
https://doi.org/10.1016/0361-9230(84)90183-7 \url{https://doi.org/10.1016/0361-9230(84)90183-7}
%doi: 10.1016/0361-9230(84)90183-7. PMID: 6722594. %doi: 10.1016/0361-9230(84)90183-7. PMID: 6722594.
%https://www.nih.gov/news-events/nih-research-matters/uncovering-origins-brown-fat %https://www.nih.gov/news-events/nih-research-matters/uncovering-origins-brown-fat
@ -572,7 +608,7 @@ Huttunen P., Hirvonen J., \& Kinnula V.
The occurrence of brown adipose tissue in outdoor workers. The occurrence of brown adipose tissue in outdoor workers.
\textit{European Journal of Applied Physiology}, \textit{European Journal of Applied Physiology},
46 (4), 339--45. 46 (4), 339--45.
https://doi.org/10.1007/bf00422121 \url{https://doi.org/10.1007/bf00422121}
%doi: 10.1007/BF00422121. PMID: 6266825. %doi: 10.1007/BF00422121. PMID: 6266825.
\bibitem{METS} \bibitem{METS}
@ -582,7 +618,7 @@ Jetté M., K. Sidney K., \& Blümchen G.
Metabolic equivalents (METS) in exercise testing, exercise prescription, and evaluation of functional capacity. Metabolic equivalents (METS) in exercise testing, exercise prescription, and evaluation of functional capacity.
\textit{Clinical Cardiology}, \textit{Clinical Cardiology},
13 (8), 555--65. 13 (8), 555--65.
https://doi.org/10.1002/clc.4960130809 \url{https://doi.org/10.1002/clc.4960130809}
%doi: 10.1002/clc.4960130809. PMID: 2204507. %doi: 10.1002/clc.4960130809. PMID: 2204507.
\bibitem{Energy_textbook} \bibitem{Energy_textbook}
@ -602,15 +638,7 @@ Madigan C.
%Carleen Madigan %Carleen Madigan
Storey Publishing. Storey Publishing.
\bibitem{USDA_1917_yields_pamphlet}
%(Cooper, 1917)
Cooper M. O. \& Spillman W. J.
(1917 October).
Human Food from an Acre of Staple Farm Products.
\textit{Farmers' Bulletin},
877,
%Morton O. Cooper and W.J. Spillman
Government Printing Office, United States Department of Agriculture.
\bibitem{PFFP} \bibitem{PFFP}
%(Muller, 2010) %(Muller, 2010)
@ -626,14 +654,14 @@ North American Bear Center.
%Ely, MN, USA. %Ely, MN, USA.
\textit{5 Stages of Activity and Hibernation.} \textit{5 Stages of Activity and Hibernation.}
%[cited 2023 Jan 16]; [about 2 screens]. %[cited 2023 Jan 16]; [about 2 screens].
\url{https://bear.org/5-stages-of-activity-and-hibernation/}. \url{https://bear.org/5-stages-of-activity-and-hibernation/}
% %
Some sources claim that bear metabolism can vary between $4,000$ to $20,000$ kcals per day, Some sources claim that bear metabolism can vary between $4,000$ to $20,000$ kcals per day,
This is comically illustrated by the National Park Service at This is comically illustrated by the National Park Service at
National Park Service, Katmai National Park and Preserve Alaska National Park Service, Katmai National Park and Preserve Alaska
(2022). (2022).
\textit{Fat Bear Week 2022}. \textit{Fat Bear Week 2022}.
\url{https://www.nps.gov/katm/learn/fat-bear-week-2022.htm} . \url{https://www.nps.gov/katm/learn/fat-bear-week-2022.htm}
\bibitem{Aztec_Cannibalism} \bibitem{Aztec_Cannibalism}
%(Ortiz de Montellano, 1978) %(Ortiz de Montellano, 1978)
@ -644,13 +672,13 @@ Aztec Cannibalism: An Ecological Necessity?
\textit{Science}, 200 (4342), 611-7. \textit{Science}, 200 (4342), 611-7.
%(May 12 1978). %(May 12 1978).
%American Association for the Advancement of Science %American Association for the Advancement of Science
Available online at \url{https://www.jstor.org/stable/1746929}. \url{https://www.jstor.org/stable/1746929}
\bibitem{potato} \bibitem{potato}
%(Salaman \& Hawkes, 1985) %(Salaman \& Hawkes, 1985)
%Redcliffe N. Salaman and J. G. Hawkes, %Redcliffe N. Salaman and J. G. Hawkes,
Salaman R. N. \& Hawkes J. G. Salaman R. N. \& Hawkes J. G.
(1985) (1985).
\textit{The History and Social Influence of the Potato}, \textit{The History and Social Influence of the Potato},
%Redcliffe N. Salaman (Author), J. G. Hawkes (Editor) %Redcliffe N. Salaman (Author), J. G. Hawkes (Editor)
(Cambridge University Press, 1985). (Cambridge University Press, 1985).
@ -664,9 +692,9 @@ Schneider C. A., Rasband W. S.,Eliceiri K. W.
NIH Image to ImageJ: 25 years of image analysis. NIH Image to ImageJ: 25 years of image analysis.
\textit{Nature Methods}, \textit{Nature Methods},
9(7), 671-5. 9(7), 671-5.
https://doi.org/10.1038/nmeth.2089 \url{https://doi.org/10.1038/nmeth.2089}
ImageJ is a free tool for measurement of photographic data %ImageJ is a free tool for measurement of photographic data
\url{https://imagej.nih.gov/ij/} %\url{https://imagej.nih.gov/ij/}
%doi:10.1038/nmeth.2089 %doi:10.1038/nmeth.2089
\bibitem{brown_fat_2} \bibitem{brown_fat_2}
@ -678,7 +706,7 @@ Shamsi F., Piper M., Ho L., Huang T. L., Gupta A., Streets A., Lynes M. D., \& T
Vascular smooth muscle-derived Trpv1+ progenitors are a source of cold-induced thermogenic adipocytes. Vascular smooth muscle-derived Trpv1+ progenitors are a source of cold-induced thermogenic adipocytes.
\textit{Nature Metabolism}, \textit{Nature Metabolism},
3, 485-95. 3, 485-95.
https://doi.org/10.1038/s42255-021-00373-z \url{https://doi.org/10.1038/s42255-021-00373-z}
%doi: 10.1038/s42255-021-00373-z. Epub 2021 Apr 12. PMID: 33846638; PMCID: PMC8076094. %doi: 10.1038/s42255-021-00373-z. Epub 2021 Apr 12. PMID: 33846638; PMCID: PMC8076094.
\bibitem{energetic_cost_of_moving} \bibitem{energetic_cost_of_moving}
@ -689,7 +717,7 @@ Tucker V. A.
The Energetic Cost of Moving About. The Energetic Cost of Moving About.
\textit{American Scientist}, \textit{American Scientist},
63, 413--9. 63, 413--9.
https://pubmed.ncbi.nlm.nih.gov/1137237/ \url{https://pubmed.ncbi.nlm.nih.gov/1137237/}
\bibitem{trout} \bibitem{trout}
%(USDA ARS, 2019) %(USDA ARS, 2019)
@ -703,9 +731,9 @@ The wilderness river might be full of trout, but if they're $300kcals$ each, you
\bibitem{USDA_FDC} \bibitem{USDA_FDC}
%(USDA ARS, 2023) %(USDA ARS, 2023)
United States Department of Agriculture, Agricultural Research Service. (USDA ARS) United States Department of Agriculture, Agricultural Research Service. (USDA ARS)
(2023) (2023).
\textit{FoodData Central}. \textit{FoodData Central}.
\url{https://fdc.nal.usda.gov/fdc-app.html}. \url{https://fdc.nal.usda.gov/fdc-app.html}
\bibitem{USDA_NASS} \bibitem{USDA_NASS}
%(USDA NASS, 2020) %(USDA NASS, 2020)
@ -713,7 +741,7 @@ United States Department of Agriculture, National Agricultural Statistics Servic
(2020, Oct 13). (2020, Oct 13).
\textit{Statistics by Subject}. \textit{Statistics by Subject}.
%[updated 2020 Oct 13; cited 2023 Jan 18]; [about 1 screen]. %[updated 2020 Oct 13; cited 2023 Jan 18]; [about 1 screen].
\url{https://www.nass.usda.gov/Statistics_by_Subject/index.php?sector=CROPS}. \url{https://www.nass.usda.gov/Statistics_by_Subject/index.php?sector=CROPS}
@ -722,53 +750,6 @@ United States Department of Agriculture, National Agricultural Statistics Servic
%\bibitem{homesteading}
%See for example, the Discover television show, ``Alaska the Last Frontier,'' any issue of ``Mother Earth News,'' or Backyard Chicken feeds on Instagram.
%\bibitem{calorie_age}
%Is $3000\frac{kcal}{person\cdot day}$ accurate for a family? For soldiers or active athletes it is, but $2000kcal$ is the USDA reference for an ``average adult,'' e.g. the author, in his 40's, and $1000-1200kcal$ for a senior age ($>60$) female. However, weeding the garden all day is physically taxing, mice will probably eat some of the potatoes, and $3000$ is a nice round number, so that's what I'm using.
%\bibitem{google_earth}
%Chinampas are still visible in sattelite imagery. See for example $latitude=19.268$, $longitude=-99.087$.
\bibitem{400k}
%(Britannica, 2022)
Britannica.
(2022, Dec 23).
\textit{Tenochtitlán},
\url{https://www.britannica.com/place/Tenochtitlan}
\bibitem{chinampas_wikipedia}
%(File:Lake Texcoco c 1519.png, 2016)
File:Lake Texcoco c 1519.png.
(2016, Aug 17).
In \textit{Wikipecia}.
\url{https://commons.wikimedia.org/wiki/File:Lake\_Texcoco\_c\_1519.png}
%Self-published work by Wikipedia user Madman2001
%\bibitem{IRE_area}
%Currently, Northern Ireland and the Republic of Ireland are separate countries. Together, their land area is about $84,400km^2$.
\bibitem{pop_image}
%(File:Population of the island of Ireland since 1600.png, 2010)
File:Population of the island of Ireland since 1600.png.
(2010, Jan 13)
In \textit{Wikipedia}.
\url{https://commons.wikimedia.org/wiki/File:Population\_of\_Ireland\_since\_1600.png}
Specific census data sources for the Ireland population plot are given at the ``talk'' page
\url{https://commons.wikimedia.org/wiki/File\_talk:Population\_of\_Ireland\_since\_1600.png}
%\bibitem{pop_sources}
%Specific census data sources for the Ireland population plot are given at the ``talk'' page of \cite{pop_image}, specifically
%\url{https://commons.wikimedia.org/wiki/File\_talk:Population\_of\_Ireland\_since\_1600.png}
\end{thebibliography} \end{thebibliography}
\end{document} \end{document}

BIN
references/pone.0079342.pdf Normal file
View File

Binary file not shown.