Electricity Review

Here is the Electricity Review (Key). I found another typo. You’ll see it when you look through the key. The videos below are the ones from the presentations in class. Please email me questions. I will not be in on Monday as I will be at my brother’s wedding. Best of luck.

Brief Intro to Voltage, Current, and Power

AC vs. DC

Charging by Friction

Charging by Conduction

Charging by Induction

Top 10 Best Lightning Strikes

What is St. Elmo’s Fire

Electric Field: An Introduction

Electric Field: Calculating Charge and Direction

AC vs. DC

How to Survive a Lightning Strike

Shanghai Maglev

Superconductor Levitation

Kirchoff’s Loop Rule


Honoring Our Rivers Welcomes Student Writing and Artwork

Submission deadline for 2015 anthology set for January 31

Since 2000, Honoring Our Rivers has showcased Oregon student writing and artwork focused on rivers and watersheds. From poetry to prose and fiction, from illustration to photography, students from across the state submit their work to a juried-review process and finalists appear before the public in an annual anthology and at exhibits, events and readings hosted by Honoring Our Rivers. Oregon schools, teachers, academic advisors, community youth programs and homeschoolers are encouraged to promote student submissions before the project’s upcoming January 31 postmark deadline.

Last year, over 900 students submitted entries to the anthology, and we distributed 4,000 copies to Oregon schools and libraries! This year, Honoring Our Rivers is working to further increase the number and diversity of submissions from around the state. The project is open to all Oregon students from kindergarten to 12th grade as well undergraduate students. All schools and students are recognized for their participation. The Honoring Our Rivers anthology is released to the public in April, in time for Earth Day, and a release celebration is held in May at Powell’s City of Books in Portland. Additional readings and exhibits will follow throughout the summer and fall.

“Honoring Our Rivers is a highly motivating learning project,” says Tom Webb, former project director for HOR. “Not only do students learn about Oregon’s legacy of rivers, they take part in the process of submitting to a publication for public consideration, a real-world writing and art practice. HOR also supports teachers’ efforts to meet state standards in the arts, English and earth sciences.”

Student work in the Honoring Our Rivers’ anthology appears alongside submissions from Oregon’s leading writers. Previous anthologies have included work by Ursula Le Guin, Brian Doyle, Barry Lopez and former Oregon poet laureate Paulann Petersen.

Honoring Our Rivers is a project of the Willamette Partnership, a 501©3 nonprofit organization. 2014-15 sponsors include the Eugene Water and Electric Board, Wildwood Mahonia, and the Port of Portland. Partners include SOLVE, Love Your River, The Freshwater Trust, Sustainable Oregon Schools, Friends of Straub Environmental Learning Center and the Oregon Poetry Association.

Trees Make Ants Chemically Dependent, Turn Them Into Indentured Servants

Trees Make Ants Chemically Dependent, Turn Them Into Indentured Servants

November 12, 2013 | by Lisa Winter
IFL Science

Ants on Acacia Tree

Ants on Acacia Tree (Photo credit: Ryan Somma)

There are all kinds of mutually beneficial relationships that exist in nature in which two seemingly unconnected species live in harmony and provide vital services for one another. This does not always result in both parties benefiting equally – but as long as it still works, it keeps on going. A recent study has shown that certain Central American ants live on and defend a particular tree not because they want to, but because enzymes in the tree’s nectar have made it impossible for them to get food anywhere else. The research team was led by Martin Heil of Cinvestav Unidad Irapuato in Mexico and was published in Ecology Letters.

The acacia tree is covered in pods that can be taken by insects. Colonies of Pseudomyrmex ferrugineus patrol the tree, protecting the pods. Some species of acacia tree even have thorns large enough for the ants to move into. In turn for their defense against predators like termites, the tree produces nectar for the ants. The nectar is rich in sucrose, a type of sugar. Using an enzyme called invertase, the ants break up the large sucrose molecules into smaller bits which can then be used to generate energy. About eight years ago, Heil’s previous research showed that the adult ants don’t even make invertase, but it is produced by the tree and can be found in the nectar. It is a classic textbook example of mutualism, or so we all thought. The truth, as it seems, is a bit more complicated.

Five years ago, Heil found out that young ants do produce invertase, but that ability is lost at some point during life. In recent years, he has searched for the answer which, he would find out, almost seems like one of the biggest betrayals in mutualism history: the tree stops the ants from producing their own digestive enzymes. Included in the sucrose and invertase is chitinase: an enzyme that blocks invertase production.

While it is true that the ants protect the tree in exchange for food, they do so because they have no other options. They are completely unable to eat from any other source, because they rely on the invertase from the acacia’s nectar. So, the tree gives them exactly what they need to live, but only because it made them invertase-deficient in the first place. The tree makes out like a bandit by having armies of ants to protect it, who will never be able to leave.

This methodology has vague (and highly anthropomorphized) connotations to Münchausen syndrome by proxy (MSbP) in which someone believes they are sick and have a dedicated caretaker, but it turns out that the caretaker was the one making them sick in the first place. In the case of the acacia tree, it is damning the ants to an eternity of servitude on top of blocking the invertase production to ensure it is the ants’ only food source.

On a very basic level, however, this is astoundingly impressive. Solely through genetic mutations over countless generations, the acacia tree has adapted a way to protect itself from predators and the ants won’t be able to leave, leaving the tree vulnerable. It just happened to evolve this way, which is absolutely amazing. You win this one, acacia tree.

Chemists show life on Earth was not a fluke

24 October 2013, 6.16am BST

In them, began life. University of Utah

How life came about from inanimate sets of chemicals is still a mystery. While we may never be certain which chemicals existed on prebiotic Earth, we can study the biomolecules we have today to give us clues about what happened three billion years ago.

Now scientists have used a set of these biomolecules to show one way in which life might have started. They found that these molecular machines, which exist in living cells today, don’t do much on their own. But as soon as they add fatty chemicals, which form a primitive version of a cell membrane, it got the chemicals close enough to react in a highly specific manner.

This form of self-organisation is remarkable, and figuring out how it happens may hold the key to understanding life on earth formed and perhaps how it might form on other planets.

The 1987 Nobel Prize in Chemistry was given to chemists for showing how complex molecules can perform very precise functions. One of the behaviours of these molecules is called self-organisation, where different chemicals come together because of the many forces acting on them and become a molecular machine capable of even more complex tasks. Each living cell is full of these molecular machines.

Pasquale Stano at the University of Roma Tre and his colleagues were interested in using this knowledge to probe the origins of life. To make things simple, they chose an assembly that produces proteins. This assembly consists of 83 different molecules including DNA, which was programmed to produce a special green fluorescent protein (GFP) that could be observed under a confocal microscope.

The assembly can only produce proteins when its molecules are close enough together to react with each other. When the assembly is diluted with water, they can no longer react. This is one reason that the insides of living cells are very crowded, concentrated places: to allow the chemistry of life to work.

In order to recreate this molecular crowding, Stano added a chemical called POPC to the dilute solution. Fatty molecules such as POPC do not mix with water, and when placed into water they automatically form liposomes. These have a very similar structure to the membranes of living cells and are widely used to study the evolution of cells.

Stano reports in the journal Angewandte Chemie that many of these liposomes trapped some molecules of the assembly. But remarkably, five in every 1,000 such liposomes had all 83 of the molecules needed to produce a protein. These liposomes produced large amount of GFP and glowed green under a microscope.

Computer calculations reveal that even by chance, five liposomes in 1,000 could not have trapped all 83 molecules of the assembly. Their calculated probability for even one such liposome to form is essentially zero. The fact that any such liposomes formed and that GFP was produced means something quite unique is happening.

Stano and his colleagues do not yet understand why this happened. It may yet be a random process that a better statistical model will explain. It may be that these particular molecules are suited to this kind of self-organisation because they are already highly evolved. An important next step is to see if similar, but less complex, molecules are also capable of this feat.

Regardless of the limitations, Stano’s experiment has shown for the first time that self-assembly of molecular machines into simple cells may be an inevitable physical process. Finding out how exactly this self-assembly happens will mean taking a big step towards understanding how life was formed.

What Created This Mysterious “Picket Fence” in the Amazon?

It’s probably the only picket fence in the Amazon, but scientists have no idea what made it or what its purpose might be.

Georgia Tech doctoral student Troy Alexander stumbled upon these two-centimeter-long white structures growing on trees in Peru on June 7.

The picket fence of the Amazon. Photograph courtesy Troy S. Alexander, Tambopata Research Center

Since then, the intricate handiwork has baffled scientists. Although most agree it was likely built by an insect, no one can identify the species that built it, or what the fence might be protecting.

“I thought anything this distinctive would have been discovered already,” Alexander said.

“I’ve talked to researchers worldwide and haven’t found an answer, so I don’t feel crazy saying that I’ve found a new species, or at the very least, a new behavior,” he said.

“What Is That?”

Alexander made the discovery when he was volunteering at the Tambopata Research Center as part of the Tambopata Macaw Project. He noticed something unusual on one of the blue tarps the group was working under for shade. (Read more about a new species of decoy spider that was discovered at Tambopata.)

“I looked up and thought, ‘What is that?’” Alexander said. “At the time, I thought a Urodid moth had started building a cocoon and then just got distracted and didn’t finish or got eaten.”

Alexander in the Peruvian Amazon. Photograph courtesy Troy S. Alexander, Tambopata Research Center

Intrigued, Alexander snapped a few photos to show an entomologist back at the center. But the expert had never seen anything like it. Neither had anyone on Reddit’s What’s This Bug group, where Alexander also posted the photo.

Soon after, he saw several more of these structures, which consist of a tall, white conical post in the middle, surrounded by what can only be described as a small, circular white picket fence.

Having spotted several, Alexander knew that this wasn’t just the efforts of a distracted moth. He posted these new photos on Reddit and got a few suggestions, but nothing conclusive. Alexander’s leading hypothesis—one proposed by a Reddit reader—is that the structure was spun and built by a spider instead of a standard web. (Also see “Photos: World’s Biggest, Strongest Spider Webs Found.”)

Instead of spinnerets, or silk-spinning organs, some spiders have what’s called a cribellum, which, instead of spinning silk fibers, pushes the molecules through a fine mesh.

“Looking more closely at the photos, I thought, yeah, that does make sense. It does look like the silk was just pushed through a mesh,” Alexander said.

Unveiling the Mystery Builder

Alexander, who’s working on his Ph.D. in natural drug discovery, said he intends to stick with his chosen field, even with the glut of attention he has received from his Amazonian discovery.

The mystery object is less than an inch long. Photograph courtesy Troy S. Alexander, Tambopata Research Center

He added he’d like to go back to Tambopata, although he doesn’t have plans to return in the immediate future. Luckily though, an entomologist will be traveling to the research center this winter to try to identify what’s building the forest fences.

When asked what he would name his find if it proved to be a new species, Alexander said he would need to learn some Latin so he could incorporate the word for “fence” in the name.

The Bestial Virus: The Infectious Origins of Werewolves, Zombies & Vampires – Body Horrors | DiscoverMagazine.com

By Rebecca Kreston | July 11, 2013 12:45 pm

Rabies is one of mankind’s long-feared diseases. And rightfully so: for centuries, a bite from a crazed, slavering animal was almost always a guarantee of a slow warping of the mind and a pained, gruesome demise. A death sentence.

I just recently finished reading about our long and tragic relationship with rabies in Rabid: A Cultural History Of The World’s Most Diabolical Virus by Bill Wasik and Monica Murphy, easily one of the finest non-fiction narratives on infectious diseases. The husband-and-wife duo have synergistically joined forces as a journalist and public health veterinarian to write a witty and thorough telling of the history and cultural mythology of the virus and the animals that it infects, us included.

The book charts the earliest mentions of rabies treatment in ancient Greek and medieval Islamic medicine, and follows its manifestations in folklore, literature and cinema, and to its eventual taming in the development of Pasteur’s hard-won vaccine. It’s a delightful read spanning the stories of Odysseus and American frontiersmen, of the Brontë sisters and Stephen King, and of Christian saints and vampires.

A canine suspected of being rabid that had been exhibiting symptoms of rabies, including restlessness and overall uncharacteristic aggressive behavior. Image: CDC.

Upon finishing the book, I felt that there appeared to be no aspect of our culture that this virus hasn’t played a role in infecting and transfiguring. But the most intriguing aspect of the book is its brief sojourn into the development of some of our most historically endurable monsters: vampires, werewolves and zombies. The authors write,

Between the fifteenth and the eighteenth centuries, Europe gestated two enduring legends whose part-human, part-animal villains bite their victims, thereby passing along their own degraded conditions.

Rabies is a scourge as old as human civilization, and the terror of its manifestation is a fundamental human fear, because it challenges the boundary of humanity itself. That is, it troubles the line where man ends and animal begins – for the rabid bite is the visible symbol of the animal infecting the human, of an illness in a creature metamorphosing demonstrably into that same illness in a person.

A hospitalized man is shown in restraints as he suffers from the final stages of the rabies infection, 1959. Image: CDC

Doesn’t this sound familiar? It’s the de-evolution of man into something not quite human but subhuman. An unrecognizable family member demonically possessed by some unfathomable but instantly recognizable animal instinct. The frothing at the mouth, the lucid madness, the lost humanity: it’s all here and stems from our ancient, tragic history with rabies and canines. To be human is a sacred and inviolable thing; rabies infection breaches that principal. The animal bite and the transmission of disease represent a moment of transgressive contact between animal mouth and human flesh, the possibility of losing one’s humanity and regressing to an animal state. Our horror stories capitalize on this lurid fear.

Our horror stories and long-constructed mythology of vampires, werewolves and the zombies that now reside in the modern vernacular are the long-lasting symptomatology of man plagued by an insensate virus. Though humans do not spread rabies – not only do we lack the sharp teeth, but the virus doesn’t prompt the infected to bite and is not shed copiously in the saliva – the potential of disease transference and the psychological horror of infection is still a marvelously rich goldmine to be pilfered and rehashed for an eager public. We’re only halfway through 2013 and already have been exposed to cinematic gems such as World War Z, Warm Bodies and Go Goa Gone, all films relying on the biologically transformed, slavering human. And there’s many, many more to come and, of course, the collective trauma of the Twilight series to be dealt with.

Rabies is of the world’s most interesting zoonotic diseases, the one that “has always shaded into something more supernatural: into bestial metamorphoses, into monstrous hybridities.” It is this concept of transmogrification, of irrevocable and deadly change that haunts our movie theatres, campfire stories and imaginations to this day even as the rabies virus’s grip on mankind’s health has diminished and faded.