Gregory Mulholland

Like all of our travels so far, our first full day of Prague was full of walking. We started in the morning by trying to go to a coffee shop called Káva Káva Káva (Coffee Coffee Coffee in English). Their espresso machine was broken though, so they weren’t really serving. We walked a few blocks over to a bookshop and coffee shop called The Globe Bookshop and Café. It was really good. They had amazing food. Being here reminds both me and Kelly how much we miss eating food with real flavor.

After breakfast, we headed over to the market (not unlike the one in Cambridge) and did some shopping. We bought a small watercolor of the city and a few other small things that will hopefully survive the trip from here to Cambridge and again from Cambridge home. We returned our purchase to the pensione and headed out for a day of sightseeing.

We boarded the underground and headed to Malostranská. This stop is at the foot of the old Prague Castle. We then walked up a bunch of stairs to the entrance of the castle. I swear we are doing a construction tour of Europe. Everywhere we go, things are under major renovation. There was no difference here. We squeezed through a narrow walkway and headed into the castle grounds. If you are wondering why I don’t have any pictures of the castle, it is because it isn’t a castle like you would normally think with a keep and walls. It is simply a fortified area of the city which has a palace and a cathedral at the center. In this case, because of some serious one-upsmanship over the years, there are like 6 palaces within the castle walls.

Once inside the walls, we went and visited St. Vitus’s Cathedral. It was started during the gothic period, but not finished until 1929, which led to some serious contrast. The stained glass was particularly varied but all equally beautiful:

After the cathedral, we walked around the palace grounds for a while. The palace itself was closed, so we couldn’t go in. We didn’t spend too much more time at the castle, since it was pretty packed with tourists. We headed back down the hill and walked toward St. Nicholas’s Church. It was pretty much the polar opposite of the cathedral that sits above it on a hill. It was covered with pink marble with enormous white statues of saints and popes and other important figures. Kelly pointed out that there was very little artificial lighting inside. The windows in the roof kept the church brightly lit. It was a remarkable place.

We then walked toward the river, and just happened to be at the end of Charles Bridge. This bridge, built in the 14^th century, was built by Charlemagne’s uncle Charles IV. It has gothic towers at either end and offers a great view of the River Vltava. From it you can see many of the domes and towers of the Old City:

We followed the road away from the bridge, and made our way to the center of the Old City. There we could see the Týn Church dominating the skyline:

Closer to earth, we were able to see the Orloj, the famous astronomical clock of Prague. It was supposed to be really amazing to see. On the hour it has a number of figures that perform. It was definitely something to see, but I don’t think it was as impressive as some say. Nevertheless, we were joined by hundreds of people on the hour to watch the performance. More importantly, neither Kelly nor I could really figure out how to read it. Upon visiting it another time, we think we have an idea of how it works, but we are still questioning a few things.

After seeing the clock, we continued to walk through the Jewish Quarter, which we will visit more thoroughly tomorrow. With this walk, we decided we had had enough walking for a bit and returned to our pensione to rest our sore feet. We headed to dinner around the corner from our pensione. It was absolutely amazing. We both had traditional Czech dishes. Like last night, the food was substantial and delicious. We tried cabernet wine from the Moravia region and loved it.

After a long relaxing dinner, we decided to take a bit of a walk to get the blood flowing. This is when we discovered something really wild: the Orloj is about 200m from our pensione. We had walked right by the place we were staying without ever knowing it. We didn’t really look at the map all afternoon and had really just wandered about, so it was really amazing that we were less than 2 blocks from it. We decided to walk to Charles Bridge again and take a look around, since we knew it wasn’t far and we had heard that the buildings looked really cool at night. I didn’t have my Nikon camera with me (which is still giving me problems), so we did our best to take some night pictures with our point and shoot cameras. Those pictures will be up soon. After seeing Charles Bridge, we walked back toward the pensione and called it a night.

Now I am trying Word 2007’s new blog post feature to see how well it will perform when I get home on Tuesday.

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FFor Christmas, Kelly gave me a great present. She was planning a trip to Prague in the Czech Republic for us. Yesterday morning, we left Cambridge for Prague. We flew with SkyEurope, a Slovenian airline that was about the same price as Ryan Air, but was very easy to deal with (as opposed to Ryan Air which nearly gives me an aneurysm every time we look at their website). We were able to board our plane with no problem and fly to Prague. Once there, we bought 3-day bus/tram/metro passes and followed our pensione’s instructions about how to get to it. We made it as far as the correct metro stop without trouble. When we emerged at street level, we tried to follow the directions but couldn’t seem to find where we belonged. We ended up using a map in our tour book to find it by its address. When we got there, we realized we had been about 50m away when we had originally followed the directions and just hadn’t been able to see it. On another interesting note, we are one street away from NCSU’s Prague Institute. We went to look for it and couldn’t find it, but it is hidden in a courtyard somewhere. Walking in on our first night, Kelly saw someone she recognized though.

We ate dinner at a little over-authentic Czech restaurant with delicious food on our first night, then we headed in to plan our first full day in the city.

I am cursed when it comes to traveling and using my debit card. Let me give you a few examples of some major trips where I have had trouble with this:

Paris and the rest of Europe
When I studied in Spain over the summer of 2003, I was planning to meet Win in Paris afterward. On the day I was supposed to leave, I packed my bags and went to the airport. There, I planned to get some Euros and top up my cell phone SIM card using the ATM. When I put my card in the airport ATM, the system locked up and wouldn’t respond to any buttons. To make matters worse, it was Sunday in Spain. Good luck getting anything done then. For the next 2 weeks and all of my travels, I was lost without my card.

Seville and Granada
This year, on the weekend before Kelly and I went to Seville and Granada, we went to London with Will and Jackie. I’m still not quite sure how it happened, but when I returned to Cambridge after that mini-trip I didn’t have my debit card any more. Of course I cancelled it right away, and within 10 days I had a new one. It did not come, however, before we left for Spain. I was stuck using my US card and paying the extra charges. Luckily, it was only for 2 days.

Prague
Yesterday, before we left for Prague, I tried (once again) to top up my cell phone. This time I was doing it online. I kept getting an error every time I tried to do it. I figured that since I had used my card the day before, the website must be at fault. I was wrong. On the way to the bus station, I stopped at an ATM to get some cash. Lo and behold, my card was rejected again. Luckily, at that ATM, I happened to be standing in front of a Barclay’s. I went in and, sensing my worry, one of the tellers told me that my account had been flagged (I guess because I had just booked a trip using my card) and that they just wanted to verify that all the charges on the account were genuine. After checking, I assured them that everything was fine. She then put me on the phone with customer service to get the safeguard removed. This, mind you, all started less than 45 minutes before we were supposed to be on the bus to Luton Airport. Finally, I was able to get it cleared up and even thought ahead enough to tell them that I would be in Prague and not to cut me off over the weekend.

I really enjoy traveling, but it seems that every time I go somewhere, something happens. Hopefully I can thwart that next time.

Easter morning was a snowy one. When Kelly and I left Wychfield, there was only barely a dusting. When we got to church, it was full-on snowing in Cambridge. We had a plan though, we had to make it to the Henley boat race. Our friend Stef is in the Women’s Blue Boat this year (that is the first women’s boat), so we were excited to see both her and the other races of the day.

From Cambridge, we hopped on a bus to Royston. Major rail maintenance goes on over the weekends, so we sometimes have to take a bus to the next station to get a train. While we were waiting for the bus to leave, our friend, and the captain of Trinity Hall Boat Club, Janet arrived. We had no idea she was coming, but it was great to have a travel companion who had an idea of where we were going. Another fellow who heard us talking about the Henley Boat Race popped up, too. We had never met him before, but he hung out with us the rest of the day. He was called Simon.

Finally, the bus was underway. At some points, because it was so snowy, we were thinking that taking a bus might not be such a good idea. It was never too bad though, and we arrived in Royston safely. From there it was Train to London->Underground to Paddington->Train to Twyford->Train to Henley. Probably the coolest part about the last part was that the line was called the Regatta Line. Henley pretty much exists for rowing.

Once there, we jaunted down to the race site not far from the station. We walked almost all the way to the finish near temple island:

From the finish, you could look down the course into town.

The day was really choppy and cold. I would not have wanted to be racing. Though I am neither a girl nor a lightweight man, so I couldn’t have even if I wanted to. Our friend raced pretty early, here is a picture of her boat:

She is sitting 3 seat. The day was tough for Cambridge. We came away with 1 victory and 4 defeats. We can make excuses about the weather, but that is rowing.

After the races, Simon, Janet, Kelly, and I all went to a pub and got lunch. Then we headed home. It seems like the weekends are getting harder than the weeks. The lab is tiring but traveling wears on you, too. It was really fun though. Next…the Boat Race and Varsity Football Match in London.

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People here always talk about the one day of snow per year. Once a year the right combination of cold and rain finally comes together to make a white coating over everything. When this happens, the photographers of Cambridge flock outside to take pictures of the snow-covered King’s Chapel, bikes, and various other Cambridge fixtures that are even more impressive under a layer of the white stuff. This year, the one day was Easter.

Kelly and I were headed to the Henley Boat Race, but by the time we were getting on the bus at 9:15, there were already a few inches on the ground. Here are a few photos:

Wychfield Site HDR



Punts on the River Cam



King’s College Chapel


We didn’t see too much more snow than that, because we were going to the race. A post about that is next!

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My trusty Nikon D70, which I bought for my first trip to Europe in 2004, may be on its last legs. I am really surprised at this because it less than 4 years old. I have only taken around 7,000 pictures with it. This, in digital camera terms, is not very many. I could understand if the mirror broke, or if mechanical failure caused the shutter not to open. All these things would be understandable because it does get pretty abused in my travels. The strange thing is this: it has stopped regularly writing to my memory cards. Every few minutes or so, the screen will flash [CHA]. I have no idea what it stands for, but it means that it can’t recognize my memory card. Even after formatting both of my cards, they continue to cause the error.

There is some precedent online for this happening. Most people send it back to the manufacturer to have it repaired. Right now, I am able to take the card out, put it back in, and get a few extra shots, but who knows how long that will last. Hopefully I can get a few more months of good pictures in Cambridge before it goes completely and I have to send it in.

Tonight, Kelly, Dominik (a guy from Kelly’s lab), and I went to see Jesus’ College Choir perform Bach’s St. John Passion. It is basically the Jesus’s Passion as told by the gospel of St. John set to music by Bach. It was a really great performance. Although it was certainly not an uplifting performance in terms of topic, the choir, orchestra, and soloists were clearly very talented. It was truly amazing how a group of maybe 20-25 singers could fill the entire chapel with pure sound. When they first started to sing, it was completely overwhelming. Over the course of the 2.5 hour concert, no one (that I noticed) missed a note. It was truly spectacular. Our companion Dominik, an Austrian and former choir singer, said that it was amazing how well he could understand the German as it was sung. The group clearly took great care to understand the words they were singing.

Interestingly, at no point did the choir show any emotion. Even at the end, rather than taking a bow, they simply turned and walked off stage. The other performers took short bows, but it was certainly not the protracted bow-and-bow-again that you see at musicals. Maybe it was the Lenten demeanor of the whole performance, or maybe it is just the style of real performers to stay reserved.

The soloists were all professional singers, some already nationally and internationally renown. It is amazing to think that there are 30 colleges here, most with choirs (Jesus is in the top 5 in terms of quality, if not higher), and they still can not only bring in great performers but also fill the seats of the large Jesus College Chapel. After Easter, we will definitely be attending more of these concerts at different colleges.

Yesterday Kelly, Will, Jackie, and I went to London to see the famed Chinese Terracotta Army exhibit at the British Museum. We originally had planned a whole day to see the city after that, but we got so hung up in the rest of the museum that we ended up staying there for a majority of the day.

The British Museum is basically a history museum of every culture investigated by archaeologists from 1800 to the late 1900s when other museums really started to grab artifacts). There is lots of controversy about what should and should not be in its country of origin rather than Britain, but I can’t complain too much since I wouldn’t have been able to see much of it if it weren’t here. Their collection holds basically everything ever photographed for a Social Studies, History, Geography, or World Cultures textbook. It is a really cool place. We spent a great deal of the day there and only saw a portion of it.

The Roof
The museum formerly had an open courtyard in the middle. One has to wonder who came up with that brilliant idea in a country where it never seems to stop misting. Nevertheless, with the Millenium Project (the same one that built the London Eye), the courtyard was covered with a geodesic dome:

I took 1,000,000 pictures of the roof. You can see them here.

The Terracotta Army
The terracotta army exhibit was a really cool thing. Tickets have been on sale and sold out for a really long time now, but they release 700 every weekend morning for the general public (500 on weekday mornings). The four of us left Cambridge super early arrived at the museum a little before 8:00. The queue looked really long:

We did get tickets right away though and headed into the exhibit:

Here is a picture I took of the army:

Just kidding, that is actually a bunch of mini-soldiers that some schoolkids made for the museum. Cameras weren’t allowed in the exhibit, but it was really neat. The soldiers themselves were very intricate. Even the bottoms of their shoes were carved. There were also all kinds of other artifacts from China and surrounding areas. It was a great experience.

Egypt, Assyria, and other Ancient Civilizations
From China, we moved onto the rest of the world. At the front of the Egypt section, probably the most famous, was the Rosetta Stone:

(The cool thing about the museum is that you could take a picture of anything you want.) I never could find the English on the Rosetta Stone…how did they translate all those heiroglyphs.

After part 1 of Egypt, we took at look at Assyria and Greece. The Greek area has a famous bust of Pericles in it:

There were also some of sculptures from the front of the Parthenon:

We also saw some ancient jewelry:

Kelly beat me to the punch and exclaimed “gold leaf!” before I had a chance to. Touche.

We moved onto the rest of the Egypt exhibit. There were sarcophagi:

and the Egyptians really knew where cats belonged: in the afterlife

Finally on the way out of the museum, Kelly and Jackie struggled to figure out what this enormous metal “art” was supposed to be:

Then, they made some faces:

After the museum, we headed to a pub for lunch. It was a really plush sorta place.

Next to the pub was a famous umbrella store. We went in for a bit. The selection was amazing. It was everything a fop would need to survive. Umbrellas, walking sticks, and flasks. I’m sure if you looked hard enough you could find combination umbrella/flasks or walking stick/flasks. It was a crazy place.

We wanted to go see Westminster Abbey, which closes early, so we headed over to Piccadilly Circus by the tube and walked down through Trafalgar Square. On the way, we ran into a rally against women’s violence. It was pretty big and loud:

We beat them to Trafalgar Square and moved on. We got to see the Parliament buildings and Big Ben:

We also tried to see Westminster Abbey, but, like I said before, it was closed for the day. We decided to move on and see Evensong at St. Paul’s Cathedral. It is a huge dome designed by Christopher Wren. The Evensong was pretty neat, even though there weren’t enough seats for us to sit close enough to the choir to hear them clearly. Around this time, too, it started to clea up:

Finally, we decided to take a walk down toward the Tower of London. It, too was closed, but we decided to explore around it anyway. I got a few neat pictures of the city, but it was really hard to get too many because it was really windy.

On the way back to the train station, we stopped for dinner. Near our restaurant was a Lamborghini dealership. I couldn’t resist taking a few photos:

As always, there are more photos at the Photos link on the right and more stories to come I’m sure.

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I am really not too good about posting regularly. Bumps was last week. I have described Bumps before and linked to the Wikipedia article, but neither of those can describe what it feels like to be there.

Bumps is a set of races on the river Cam. It also consumes your life during those 5 days. This year, I was bank party (on-shore helper) for the Kelly’s boat every day in addition to racing in mine. Each boat marshals upstream from the start about 40 minutes before their race is set to begin. Here is a cool picture Kelly took of the other boats marshaling.

On the way from the marshaling point to the starting area, everyone is allowed 1 or 2 starts, depending on the weather. This year, it was just 1. Here is Kelly’s boat doing a start:

And here is mine:

Then, it is a leisurely row to your respective starting station to wait for the race.

For those of you who have rowed before, Bumps is a combination sprint-head race. Boats are staggered, so you can see the crews seeded behind you, but you can’t see any crews in front (obviously). Rather than being a start staggered by time, it is a start staggered by distance. Boats from the college boat clubs line up along the side of the river in last year’s finish order. A cannon is fired, this marks the 4 minute count down to race time. The cannons are only about a foot and a half long each, but they do pack a punch.

If you are nearby, its more of a feeling than a sound. It definitely adds to the suspense of the event. The 4 minute gun is typically when everything really begins to happen. By this time, your stroke has given you the on-land talk while marshaling. People are thinking about de-kitting (British for taking off all the warm clothes you brought and leaving them with your bank party). Finally (this one is for you, Donny), because you are pulled into land, you can get out and use the facilities (bushes) before your race.

When 1 minute before race time comes, another cannon fires (now see why there are three cannons?). Because the next one will fire at the start, one member of the bank party keeps time. This way, the boat and other bank party members know about when to expect the gun. It has been drilled into me, though, that cannon fire is an inexact science, so it can actually fire about +/- 5 seconds from expected. When 30 seconds has been counted, another bank-partier begins to push the boat off with a 3m long pole. A good pusher keeps the boat straight and moves it into position quickly. This is a very important job. Also at 30s, the counter begins to count aloud.

With 12 seconds to go, crews are in starting position. With 7, everyone squares blades. With 5, the count stops, and the gun could come any time. Then you hear the bang and all hell breaks loose. First, every boats bank parties are running alongside yelling. They usually have whistles to tell their crew about their progress. 1 blast means within 1 length. 2 blasts means within half a length. 3 blasts means nearing overlap. Finally, a bell ringing or just general haphazard blowing of the whistle means “I can’t control my bladder you are so close to bumping the crew in front of you!” or something like that.

Bumps is like a series of 100m races. In a most races, you know how far you are going. You will race 5k or 2k or whatever. In bumps, you row as hard as you can for 100m. If you don’t get bumped or bump the crew in front, you row as hard as you can for another 100m. You do this 25 times until you row over. You can see the crew behind chasing you, but you can never see the one in front. It is one of the most intense psychological games I could imagine.

Kelly and I each rowed four races. Her boat started in the 3rd women’s division. They got bumped on the first and second days, rowed over on the third day, and got bumped on the fourth day. I think everyone in her boat was proud of their performance. They were a fairly novice crew and by the end of the week were rowing quickly.

My boat was bumped all four days and got what is referred to as spoons (as opposed to blades, which is what you get if you bump every day). Although from an object point of view we didn’t do so well, everyone in my boat agreed that we got much faster every day. Much of our crew was fairly inexperienced as well, but we matured greatly as time went on and turned into a quick boat. Below, you can see the bumps charts for this year’s races: men’s and women’s. On the left is the starting position of each of the boats. On the right is the position of every boat after the last day of racing. The zigzag in between is the boat progress on each day.

Women’s:

Men’s:

There is a gallery of my bumps pictures at http://g-amor.smugmug.com/gallery/4423531_KTfEt#259909089 Be sure to check it out.

After the last day of bumps was an exciting night of Boat Club Dinner. I will write a post about that and get the pictures up soon.

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I guess since I am here to do research, all my family and friends should know a little about what I do here in terms of research. Plainly, I work with semiconducting oxides.

I know most of you know that I work with things that are trying to improve the efficiency of solar cells, that is, increase the amount of electrical energy output per unit light input of a solar cell. To do this, I am working with conductive and semiconductive oxides. These are typically metals mixed with oxygen. In my case, I am working with Titanium dioxide (TiO2) and Tin Oxide (SnO2).

Now, for some background: several years ago, a type of solar cell was devised that is called a hybrid organic-inorganic solar cell. These cells have a metallic or oxide part (inorganic) and a part made from a polymer (organic). These cells typically have a better efficiency than purely organic ones but do not do as well as purely inorganic ones. What is nice about them, though, is that they let us carefully examine how organic and inorganic layers connect.

Because these have been around for a bunch of years, a lot has been done with these cells. Different polymers have been tried, different oxides have been tried, lot of combinations have been made. Mine is a pretty new combination, but it is not exclusively the material that is the focus of my work.

Nanowires
Like I said before, I work with what happens at the interface between the two materials. What happens in the main part (officially the bulk) is well known. I am growing what are known as nanowires at the interface. If you want to be able to picture this (I will post real pictures at some point when I know what the rules are on publishing images), think flat hairbrush. There is a single flat surface with really fine, long tines sticking up from it. The reason we want nanowires is twofold. First, these wires are just that, wires. Charges (and thus, energy) can flow down them very efficiently in the long direction. Second, they greatly increase the surface area of the oxide. A flat surface has only one plane of contact. A comb-like surface has all those edges that can make contact with the surrounding material. Because the interface is so much larger now, its effect is maximized and I can compare the materials.

There are other challenges with nanowires: it is hard to get stuff between them because they are so small, they break easily, they are really hard to see (even with an electron microscope). All of these are in various stages of being overcome by me or one of the others working on my project.

Excitons are exciting!
Now into the nitty gritty. If you are not interested in reading about the hardcore science behind what I do, feel free to skip.

My ultimate goal is to hold on to, or keep alive, as many excitons as possible. What is an exciton? Well that is easy! It is a bound, electron-hole pair. If you are Saket, Ben, or Win, you probably understand this, otherwise, here is my quick sentence explanation:

Electrons sit on tracks. These tracks are at different energy levels. An electron can only travel on these tracks (officially known as bands, but tracks are a better common-sense descriptor for this example). So, if I have an electron on a track at 1 Volt, and I want to make it travel on a track at 2 Volts, I have to apply more energy to it to get it there. If if give 1/2 Volt to a 1 Volt electron, it can’t just jump to the 2 Volt track. Tracks are very well defined for all materials, the space between them is known as the band gap and varies by material.

I’m sure most people remember from high school chemistry that electrons (an just about everything else, including me) like to sit in the lowest energy state possible. If an electron can move to a lower track, it will. Thus, the low tracks get filled up fast. In fact, one can define a top level to the electrons. This (a simplification of Fermi level) means that the electrons are like sand grains on a beach. They all pack nicely into their layers with only slight variations on top. But, because they pack so tightly, there is little room for them to move. There is essentially an electron traffic jam on the lower tracks. The only way to allow and electron to move with any haste is to move it up to one of the unoccupied tracks.

Solar cells work by letting the sun provide the extra energy to move an electron from one track to the next one up. This allows the electron to zoom down the nearly empty track toward whatever you are trying to power with the solar cell. The electron leaves a space behind it where it formerly took residence on the lower track. Because the electrons are packed so tightly, they begin to, one by one, move to fill the void left by the zooming electron. This creates a propagating gap (known as a hole) down the lower track, just like when one car is able to get through in a traffic jam.

This electron-hole creation is called an exciton. My goal, like I said, is to make this last as long as possible. The longer I can make them last, the more electrons are able to escape into the next material and be used for energy. How do they die? This is simple, if the electron and hole do not get away from each other fast enough, they will be attracted to one another and the electron will fall back into the hole, and no energy will be extracted.

So, with all of that said, I am trying to grown Tin Oxide and Titanium Oxide nanowires and make them ideally suited for solar cells. As time goes on and I have more results (which are finally beginning to look rosy), I will post some pictures and descriptions for those of you who are interested.

If this all is totally unclear, let me know and I can try to explain it using a whole different set of metaphors

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