Animal Appreciation I: Giant Pacific Octopus

The Giant Pacific Octopus is the largest octopus, reaching around nine meters across.  Here’s a few reasons why the Giant Pacific Octopus (and all octopuses in general) are super cool:

1. They are great mothers.  While I usually have issues with anthropomorphizing creatures, these animals are extremely dedicated to their young.  An octopus can have hundreds of offspring, and a female will lay the eggs and wait with the eggs until they hatch to ensure that they stay safe from predators.  Of course, this means that the octopus cannot go and eat for herself, so she usually dies after these months of fasting.  However, they ensure that at least some of their offspring survive.

2. They are incredibly intelligent.  We usually refer to intelligence solely to mammals (humans, other primates, dolphins, etc.) but octopuses are very smart.  They have been given mazes and puzzles to solve and they consistently find innovative solutions to these problems.

3. They have no bones.  Like most cephalopods, they have no bones (in fact, the only hard part of their body is the beak in the middle of their tentacles that they use to eat).  Therefore, any hole that the beak can fit through, they can fit through too – they have been shown to fit through holes no bigger than a quarter (and these are big animals).

4. They are fierce predators.  Apparently at an aquarium, some workers decided to move the octopus into a tank with sharks, hoping that the sharks wouldn’t hurt the octopus because the octopus could hide well.  Of course, mysteriously the sharks started disappearing from the tank.  Here’s the crazy video of an octopus eating a shark:

5. Camouflage.  I saved the best for last; this is incredible.  Octopuses have amazing abilities to camouflage and blend into their surroundings; they change both the color and the texture of their skin.  How does this work?  These creatures have cells called chromatophores that change size by muscle contraction.  When these cells change size, they can change the way light interacts with the skin, changing the color of the skin at the animal’s control.  Here’s an absolutely amazing video of an octopus camouflaging:

That video is taken from an equally amazing TED lecture about ocean astonishments: http://www.ted.com/talks/david_gallo_shows_underwater_astonishments.

Side Note: Octopi is actually not the correct plural form of octopus.  The word octopus is derived from the Greek derivative, not the Latin derivative, and therefore the correct plural is actually octopodes.  However, since the word is in English, octopuses is correct too.

Works Cited

http://animals.howstuffworks.com/marine-life/octopus-camouflage2.htm

http://www.scientificamerican.com/article/how-do-squid-and-octopuse/

http://animals.nationalgeographic.com/animals/invertebrates/giant-pacific-octopus/

http://www.seattleaquarium.org/octopus

http://www.montereybayaquarium.org/animal-guide/octopus-and-kin/giant-pacific-octopus

New Series of Posts: Animal Appreciation

It’s easy to appreciate some animals; mammals are  furry and make cute noises, some fish are beautiful and brightly colored, birds chirp and (some of them) sing complex songs.  However, there are far more animals that many people consider “gross” or “unpleasant to look at” that are in fact incredible creatures.  However, sometimes it’s hard to notice or realize how amazing they are.  Therefore, I am starting a series of posts dedicated to the creatures that are sometimes misunderstood.

First up – Giant Pacific Octopus!

How Bad is High-Fructose Corn Syrup?

File:Sugar 2xmacro.jpg

Sugar; found at: http://commons.wikimedia.org/wiki/File:Sugar_2xmacro.jpg; photo by Lauri Andler.

High-fructose corn syrup is in everything nowadays; it’s used as a sweetener and an alternative to just table sugar in most foods.  Many people are very concerned with the health of high-fructose corn syrup, especially because it is most often found in high levels in processed foods.  However, is it really as bad as some people think?

The Basics

Sucrose is the sugar that most people interact with; it’s table sugar, but it is also in maple syrup, cane sugar, and beet sugar, the most common sweeteners besides high fructose corn syrup.  Sucrose is made up of a molecule of glucose bound to a molecule of fructose (both of which are individual sugar units).  When this sugar is ingested, it is subsequently broken down into the individual units of fructose and glucose to be taken up in fat storage or used as energy.

While fructose and glucose are both sugar units, they are used by the body in different ways.  Glucose is broken down by the body in many different ways, including generating ATP, the energy of the body.  However, fructose is only broken down in the liver.  Therefore, when the liver receives more fructose than it needs, it automatically stores that all into fat, and a buildup of too much fat can be bad for you.  There also has been some research done into how the body determines when it has to much fat; it turns out that fructose, unlike glucose, does not stimulate the parts of the body that tells you when you have had too much sugar or too little sugar.  This makes it far easier to eat too much.  So, it is definitely true that too much fructose can be bad for you.

High Fructose Corn Syrup – Any Different From Other Sweeteners?

However, it is not true that high fructose corn syrup is pure fructose.

Common table sugar (sucrose) is 50% fructose and 50% glucose.  high fructose corn syrup varies in its concentration of fructose – HFCS 42 is 42% fructose and HFCS 55 is 55% fructose, neither of which are extremely different from regular sucrose.  And, even though HCFS 55 contains more fructose than table sugar does, since it is far sweeter than table sugar, manufacturers use less.  In fact, this was the motivation for developing high fructose corn syrup in the first place; sweeter sugar means they can use less of it and save money.  It is not clear whether they use little enough sugar to offset the extra fructose, but at best it would be a minimal difference if you ingest the same amount of high fructose corn syrup and table sugar.

File:Relativesweetness.png

Table of sweetness; Found at: http://commons.wikimedia.org/wiki/File:Relativesweetness.png

Are natural sweeteners better?

Many people have started using honey or agave nectar as better alternatives to regular sugar.  Honey actually has 50% fructose and cooked agave (according to the USDA) is 87% fructose (although this is disputed, some claim it is 70%).  Fruit juices are also high in fructose, with the sugar in pears being 64% fructose and the sugar in apples being 57% fructose.  Now, this is not to say that fruit or natural sweeteners are bad for you – fruit has a lot of good nutrients and fiber and in moderation it is extremely good for you.  However, it isn’t necessarily true that these alternatives are “healthier” than regular table sugar in their levels of fructose and glucose.

So why are people concerned about high fructose corn syrup?

Because it is in everything, even things that don’t necessarily need a lot of sugar, like bread.  This has more to do with society’s extreme sweet tooth than high fructose corn syrup itself, but it is important to watch how much sugar (be it table sugar, honey, or high fructose corn syrup) you intake to make sure you don’t have too much.  However, high fructose corn syrup itself is not much worse for you than any other “natural” sweetener, in moderation.

Works Cited

http://www.sciencebasedmedicine.org/high-fructose-corn-syrup/

http://sweetsurprise.com/hfcs-myths-and-facts

http://www.mayoclinic.org/healthy-living/nutrition-and-healthy-eating/expert-answers/high-fructose-corn-syrup/faq-20058201

http://recipes.howstuffworks.com/high-fructose-corn-syrup2.htm

With All This Talk of Ebola, What’s Happening with Lassa?

File:Lassa virus.tif

Found at: http://commons.wikimedia.org/wiki/File:Lassa_virus.tif

Given the most recent outbreak of Ebola, there have been a lot of people calling to increase medical attention in the affected parts of Africa and dedicate more vaccine research towards Ebola.  But why don’t outbreaks of Lassa cause the same concern?

The Lassa virus is another pathogen that causes hemorrhagic fever, with very similar symptoms to Ebola (symptoms that strike fear in all our hearts), including serious loss of blood, and can kill its host in about two weeks.  While Lassa only shows these severe symptoms in about 20% of the patients, it kills about 5,000 people per year, more people than Ebola has killed since 1976, with about 100,000 to 300,000 cases per year (all data according to the Center for Disease Control).  And, although Lassa certainly has not in the past been quite as deadly as Ebola, which can kill up to 90% of infected individuals, the number of cases and number of affected people clearly dwarf Ebola.

But, as with Ebola, there is currently no vaccine and no cure, which is even more surprising because we have characterized the virus and know the vector (or the animals from which the disease is transmitted), a rat called Mastomys natalensis.

While it is very understandable that people are concerned with Ebola at the moment, because this outbreak is so out of the ordinary, it does bring up questions as to why Lassa outbreaks (or any other viruses that cause hemorrhagic fevers) do not get similar media attention.

Works Cited

http://www.afro.who.int/en/clusters-a-programmes/dpc/epidemic-a-pandemic-alert-and-response/outbreak-news/4236-ebola-virus-disease-west-africa-29-july-2014.html

http://www.medpagetoday.com/InfectiousDisease/GeneralInfectiousDisease/45120

http://www.cnn.com/2014/08/01/health/ebola-outbreak-questions/index.html

http://www.cdc.gov/vhf/lassa/

http://www.scripps.edu/philanthropy/ebola.html

http://www.who.int/mediacentre/factsheets/fs103/en/

Will the Ebola Outbreak Become an Epidemic: A Look Into Epidemiological Models

File:Ebola virus em.png

The Ebola Virus.  Found at: http://commons.wikimedia.org/wiki/File:Ebola_virus_em.png

When diseases start to spread unusually or appear more threatening than usual, we have to figure out what the probability is that the disease will spread and become an epidemic, and this is most often done using mathematical models.  If we can model the spread of the disease, using certain parameters specific to the pathogen, we can get a sense of how many people could be infected and how we should respond to the threat.

This is becoming most pertinent now because currently there is an outbreak of Ebola in Africa, spreading from Liberia to Nigeria, and there has been some concern on the news about an epidemic spreading to the United States.  This would be especially problematic because there is no known vaccine or treatment for Ebola.  But, will it actually spread to affect many other countries in the world?

The most common model for diseases is known as the SIR model (which stands for Susceptible Infected Resistant).  In this model, people in the population are either susceptible to the disease (as in they have not contracted it yet), infected with the disease, or they have been infected and recovered and they are now resistant to the disease.  We can plot the spread of the disease as a function of the number of people in the population, the transition rate, and the number of people with the disease at a certain time t, and we get a curve that looks like this:

File:Logistic.png

Found at: http://commons.wikimedia.org/wiki/File:Logistic.png.

Ignoring what the axes mean in this graph, this curve is known as a logistic growth curve.  The disease starts out slow, infecting only a few people, then as more people get it, they pass on the disease to more people, and the disease spreads faster.  Then, it hits a time where so many people are infected and now resistant that the spread slows down and eventually stops.

But, as far as we know, Ebola is not one of the diseases where people who get it once are necessarily resistant.  So then, how does the model change?

Then we can use the SIS model (susceptible infected susceptible), where people can recover from the disease but once they have recovered, they are then susceptible to the disease again.

So, say that people are recovering at some rate a, and the transmission rate is t.  If a > t (or if people are recovering faster than the disease transmits) then the disease won’t spread.  Say the contact rate (the rate of infected people contacting not infected people) is c, then with some math we can figure out that the disease will spread if ct-a is positive, and if ct-a is negative, the disease won’t spread.  We call that number ct-a R, or the basic reproduction number, which tells us the number of susceptible people infected from a single infected person.  If R<1 the disease does not spread, and if R>1, the disease spreads, which makes logical sense because if a single person can infect more than one person, the disease will spread.  If a single person cannot infect one person, than the disease will slowly decline.

We have calculated the R’s (basic reproduction numbers) of certain common diseases; for example, the R of measles is 15 and the R of the flu is 3 (meaning both diseases spread easily, measles way more than the flu).  On a side note, this is why the recent resurgence of measles cases, potentially due to a fear of vaccinations, is so worrisome.

The R for Ebola is hard to say for sure, because R is calculated using data from past cases.  Unfortunately, as of 2004, there have only been a few big Ebola outbreaks, including one in Congo in 1995 and one in Uganda in 2000.  From these two cases, a group of researchers determined that the R is about 1.83 for the Congo outbreak and 1.34 for the Uganda outbreak.  Another group of researchers found the R value to be around 2.7 instead.  This does not necessarily mean that this will be the R value for the current outbreak because there isn’t enough data to say for sure, but it does suggest that the Ebola virus does spread, but not as well as diseases we interact with a lot like the flu.

Why might Ebola have a (comparatively) low R value?  The transmission rate could be low; ebola requires direct contact with bodily fluids with an animal or another human, which occurs far less than contact with viruses that spread in the air or just by touch.  Ebola patients are also contagious for a relatively short amount of time before showing symptoms, so if Ebola is correctly identified quickly (and that is a big if because Ebola is notorious for being misdiagnosed), patients may not be able to spread the disease to many people.  Finally, Ebola tends to kill its host (or show bad enough symptoms that an infected person is hospitalized and under quarantine) fairly quickly, making it harder for an infected person to transit the disease to many people.

Now, this is not to say that the possibility of an Ebola epidemic is zero, because this is currently the biggest Ebola outbreak and it is spreading farther than is usual for Ebola.

However, there is some good news to come of mathematical models – some researchers (their paper can be found here http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2870608/) looked into modeling an Ebola outbreak after medical interventions have occurred (including medical treatments, hospitalizations, and quarantines) and found that the R value dropped significantly (to 0.4 and 0.3, meaning the disease would not spread).  They also found that the time it took for these interventions to happen was one of the determining factors in how big the epidemic would be (as well as decreasing the rate of transmission after death; there have been cases where people have contracted the virus while burying victims of the disease).

Models are never perfect; for example, this particular one did not take into account animal to human transmissions.  However, even simplifications can tell us a lot.

If anyone is interested in modeling, there’s a really cool (and free!) online class on Coursera (coursera.org) called Model Thinking and it’s all about going through different types of models and it actually goes through epidemiological models too.  You should check it out if you’re interested!  https://www.coursera.org/course/modelthinking.

Works Cited

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2870608/

http://home2.fvcc.edu/~dhicketh/DiffEqns/Spring2012Projects/Zach%20Yarus%20-Final%20Project/Final%20Diffy%20Q%20project.pdf

http://mtbi.asu.edu/files/Mathematical_Models_to_Study_the_Outbreaks_of_Ebola.pdf

http://math.lanl.gov/~mac/papers/bio/CHCFH05.pdf

http://www.who.int/mediacentre/factsheets/fs103/en/

http://web.stanford.edu/~jhj1/teachingdocs/Jones-on-R0.pdf

http://www.ncbi.nlm.nih.gov/pubmed/15178190

http://ebola.emedtv.com/ebola/ebola-incubation-period.html

Coursera Course, Model Thinking

How Does Nuclear Power Work?

Many people consider nuclear power to be the future of alternative energy, the solution to climate change and creating a sustainable future.  Others think of nuclear power as far too dangerous and risky to be worth any potential benefits.  So how can we determine how safe nuclear power is?  Well, the first step is to examine how it works…

How do power plants in general create electricity?

Most power plants use some sort of fuel to create heat which then boils water.  This water vaporizes into steam, which is then used to turn a big turbine (as shown below).

File:Altbach Power Plant Turbine on display.JPG

Found at: http://commons.wikimedia.org/wiki/File:Altbach_Power_Plant_Turbine_on_display.JPG.

This turbine spins, creating mechanical energy, and is attached to a generator which turns this energy into electricity.  Both coal-based power plants and nuclear power plants work this way, but the type of fuel they use is different.  Coal-fired plants burn coal to release heat that generates steam.  Nuclear power plants, on the other hand, use nuclear fission.

Nuclear Fission

Everything is made up of atoms, which in turn are made up of a nucleus, the “center” of the atom that contains protons (positively charged) and neutrons (not charged), and electrons (negatively charged), which exist in the space surrounding the nucleus.  Nuclear fission involves splitting an atom, releasing a lot of energy, that is then used to heat the water in the power plant.

During fission reactions, atoms (typically radioactive atoms like uranium, which are very big and therefore easier to break apart) are hit with lone neutrons, causing the atom to split and release more neutrons.  The atom splits because, when the atom comes in contact with the free neutron, it incorporates the neutron into the atom, causing the atom to destabilize and break apart.  Those neutrons that are released then conduct other fission reactions with other atoms, creating a chain reaction.  To prevent the reaction from spinning out of control, the power plant also has control rods that can absorb free neutrons and stop the reaction if needed.

File:Kernzerfall.svg

A picture of a nuclear fission reaction, found at: http://commons.wikimedia.org/wiki/File:Kernzerfall.svg

How is a nuclear power plant set up?

The uranium must be enriched, and then it is set up into rods and bundles of rods that are put inside water to prevent them from melting during the reaction.  Then, it heats up that water and turns it into steam, which then goes through a tube to heat up other water that then interacts with the turbine and turns it (so the radioactive materials never go near the turbine itself).

It it Dangerous? 

These reactions can release radiation, which comes in multiple different forms.  Some radiation is high energy electrons being released from the reaction, some is high-energy protons.  There are multiple levels of safety measures taken at any nuclear power plant, including making the containment vessel coated in steel and two levels of concrete protecting the vessel.

The radioactive waste definitely does have to be taken care of safely, and there is still a debate going on about exactly how to best ensure the safety of everyone when disposing of the waste.

In the next few posts, we will look at the problems at Chernobyl and Fukushima, and exactly how safe nuclear power really is in comparison to current types of energy production.

Works Cited

http://science.howstuffworks.com/nuclear-power.htm

http://www.world-nuclear.org/info/Country-Profiles/Countries-T-Z/USA–Nuclear-Power/

http://www.ucsusa.org/nuclear_power/nuclear_power_technology/how-nuclear-power-works.html

http://www.nei.org/Knowledge-Center/How-Nuclear-Reactors-Work

http://www.energyquest.ca.gov/story/chapter06.html

Global Warming Potential: How We Measure Harm to the Environment

There are lots of different greenhouse gases – including water vapor, methane, nitrous oxide, and, of course, carbon dioxide.  So why is everyone so concerned about just carbon dioxide – why aren’t we focusing on the other gases?  Part of it has to do with global warming potential, which is a measure of how much heat energy is absorbed by each gas and how long those gases stay in the atmosphere.

File:Annual greenhouse gas index, 1979-2008 (EPA, 2010). Indicator of radiative forcing.png

The above is a graph of the different greenhouse gases and how concentrated they are in the atmosphere over time – found at http://commons.wikimedia.org/wiki/File:Annual_greenhouse_gas_index,_1979-2008_%28EPA,_2010%29._Indicator_of_radiative_forcing.png.

Greenhouse gases become a problem when they absorb a lot of energy and stay in the atmosphere for a very long time, allowing a single molecule of the gas to absorb far more heat as time goes on.

For example, water vapor is one of the most potent greenhouse gases because it absorbs a lot of heat (far more so than carbon dioxide), but its concentration in the atmosphere changes almost daily as atmospheric temperatures change and precipitation happens.  Therefore, it does not have time to sit in the atmosphere and collect heat, making the atmosphere warmer.  (However, there is some evidence that if temperatures keep increasing due to other gases, like carbon dioxide, more water vapor will collect in the atmosphere, further exacerbating global warming – this is known as a positive feedback).

On the other hand, nitrous oxide stays in the atmosphere for a long time (about 114 years) and can absorb a lot of heat in that time, making it even more potent a greenhouse gas than carbon dioxide.  To see a full list of global warming potentials from the UN, go here: http://unfccc.int/ghg_data/items/3825.php.

So, if there are much more potent greenhouse gases, why focus on carbon dioxide?  Because carbon dioxide is a potent greenhouse gas and it is increasing in concentration far faster than the other gases, making it a big problem.  There have been other efforts to reduce some of the other gases (the Montreal Protocol banned in some countries CFC’s and other gases with high global warming potential), but at the moment it seems that carbon dioxide is the biggest concern.

Works Cited

http://unfccc.int/ghg_data/items/3825.php

http://www.global-greenhouse-warming.com/global-warming-potential.html

http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch2s2-10-2.html

http://www.ghgprotocol.org/files/ghgp/tools/Global-Warming-Potential-Values.pdf

"Science is a way of thinking much more than it is a body of knowledge" – Carl Sagan

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