August 4, 2008

Annual reports from years 1, 2, 3, 4, 5, 6

Chicago students in Chile June-August 2007

Seven students accepted internships in Chile after video meetings with their prospective advisors. All were U. of C. undergraduates
• Alex Moore, entering his 3rd year worked at USACH with Prof. Cerda. His project was a study of the three-dimensional geometry of a torn elastic sheet. The torn border of a sheet is not straight but curves. This curving is thought to arise from basic features of the geometry of the sheet that are independent of material. Alex made measurements with different materials and geometries and wrote Matlab programs to analyze the shapes of the tears.
• Wei Ng, entering his 4th year, worked with Prof. Rodrigo Soto on a numerical simulation of an experiment to measure acoustic interaction between macroscopic bodies. Two small spheres are immersed in liquid in a narrow tube. These balls move to favorable positions when sound is sent into the tube. Their simulation enabled them to try several operating conditions and parameters in order to guide the experiment.
• Lee Walsh, entering his 4th year, studied nonlocal response to external forcing of thin sheets with Prof. Eugenio Hamm of the Universidad de Santiago (USACH). External point forces on a thin plastic cylinder make deformations far from the points of contact. This leads to attractive or repulsive forces between two such forcing points. Lee made a set of suggestive measurements showing both attraction and repulsion. These measurement aroused the interest of fellow intern Wei Ng and led him to do a senior undergraduate thesis to simulate Lee's experiment the following term. This thesis was done under the supervision of Prof. Witten, the Chicago co-ordinator. The measurements held ongoing interest for Lee himself. He will continue his studies with Prof. Hamm in a second internship under this program in September, 2008.
• Ivan Teo, entering his second year, worked with Prof. Rodrigo Hernandez at UCHILE. He designed a finite-element simulation of a Rayleigh-Benard cell, for testing thermal control. It took account of the thermal response of the cell, especially the diffusion of heat to the cell. Using this simulation he could recommend design parameters for the control protocol and also design features of the physical heater.
• Elliott Brannon, a beginning 4th year student worked in Prof. Mujica's lab at the Universidad de Chile (UCHILE). The experiment aims to demonstrate acoustically induced interactions between macroscopic balls in a narrow fluid-filled tube. He built several variants of the apparatus and tested them for maximum acoustic interaction and minimum mechanical vibration. His extensive report will guide future design of this apparatus.
• Michael Miller entering his 4th year, worked with Prof. Melo on a biophysics project. This ongoing project studies the interplay between tensile stress and growth of a living nerve axon. The experiment uses a magnetic bead micro-rheometer to exert controlled forces on the axon over time. Mike wrote software to control video data collection using Labview.
• Kanika Jhunjhnuwala, entering her 3rd year, worked in the lab of Prof. Denardin at USACH on the motion of magnetic domain walls in ferromagnetic materials. Using sensitive inductive pickups, the apparatus can sense the velocity of the domain walls.

  Results from Chicago-to-Chile program 2007

  Overall the students expressed satisfaction with their internship experience. One spontaneously wrote an enthusiastic email about how much he was learning. Some students occasionally felt disconnected from their advisors. The students organized a car trip to the Valdevia region and to the Cerro Tololo observatory. Prof. Cerda as usual organized some weekend outings. Some of the students' pictures appear here.

  Housing arrangements went smoothly. The students rented two apartments during their first week, using leads prepared by Prof. Mujica.

  Funding changes

  Payments to the Chicago students were handled by the same method worked out in the previous years. The students were given University travel advances sufficient for their plane tickets plus a few weeks of living expenses. They then justified the advances upon their return by providing proof of expenses.

Chileans in Chicago: January-March 2008

We received five students from Chile this year, identified in the table below. As before, each student was introduced to their prospective supervisor via a video meeting, and an agreement was reached on a project. Each student made good progress on a project, and several were quite successful. In some cases the progress was hampered by the language barrier, as discussed below.

student	institution	supervisor(s)
Tibor Heumann	U. Chile	Binua Lin
Jocelyn Dunstan	U. Chile	Heinrich Jaeger
Cristian Erices	U. Chile	Juan Collar
Nicolas Rivas	U. Chile	Ka Yee Lee, Luka Pocivavsek
Daniel Rivas	U. Chile	Cheng Chin

The students and their projects are described in more detail here.

Changes and lessons learned

• administrative hitches. Problems occurred in past years by mis-transcription of information, by delays in Social Security Administration processing and by difficulties in by the U of C payroll office in complying with Social Security rules. There was some inconvenience and expense stemming from the students' misunderstanding of the University's vaccination requirements. Thanks to the vigilance of Administrator Pegg Anderson, such problems were minimal this year.
• English language problems. Beyond the students who came to Chicago, several others were interested in coming, notably several from USACH. However we judged that these students' English skills were not good enough for them to be successful in their internships. One drawback of this English problem was that all of this year's Chile interns were from UCHILE. With Prof. Cerda at USACH, we have begun a plan to reduce this problem. Prof. Cerda has engaged an English language instructor named Moses Montgomery, with partial support from the Chicago-Chile program. Montgomery organized English language sessions for USACH physics students who are potential interns in our program. Moreover, the 2008 Chicago students spent 10-15 hours during their initial weeks in Chile English conversation sessions with these students.
• recruiting visit. The Chicago co-ordinator, Prof. Witten, attended a Chilean science meeting and met extensively with Chilean partner scientists in early November, 2007.

Chicagoans in Chile, June-September 2008

Five interns were chosen for the program this year. Four students are currently performing their internships in Chile. All are Chicago undergraduates. The students and their supervisors are as follows.

student	institution	supervisor(s)	topic
Andrew Alexander	USACH	Prof. Melo, Dr. Bernal	response of bone cells to forces
Samuel Oberdick	UCHILE	Prof. Mujica	turbulent surface-tilting transition
Daniel Citron	USACH	Prof. Soto	long-range correlations near granular phase transition
Jonathan Cheng	USACH	Prof. Melo, Dr. Vivanco	force patterns in sheared granular layers of photoelastic disks

Reports from both the students and the two program co-ordinators in Chile say that the students are doing well.

In addition, Lee Walsh, a 2007 intern listed above will return to Chile this September to continue his work on nonlocal interaction of deformed membranes with Prof. Hamm.

• Recruiting events. In addition to publicity via posters and classroom announcements, the program organized three information meetings. In February Prof. Witten spoke to the local chapter of the Society of Physics Students to tell them about the program. In February the program organized an open house for current Chile interns and their Chicago research groups. This event also included former and prospective Chicago interns. About 30 people attended.
• reduced recruitment. The number of Chicago interns was lower this year than in recent years. We attribute this decrease to reduced recruiting effort by the Chicago Co-ordinator. Our prospects for funding these students were somewhat uncertain because during the recruiting period continued funding by NSF had not yet been secured.

Renewal of program

In September of 2007 we applied for a renewal of the funding NSF grant. The proposed program built on the success of the current and included a few changes, notably
• English language sessions. As noted above, Chicago students are now expected to spend significant time in English conversation sessions during their first weeks in Chile.
• Sustainable size. The initial funding cycle showed us that we can comfortably accommodate about six internships in both directions. More students than this stretch the capacities of all three partner institutions to offer good projects and provide good supervision. Accordingly the new proposal provides for just six students in each direction per year.
• supply budget. The new proposal provides a small budget for the supplies that the Chilean students use.
This proposal was subsequently funded for four years at essentially the requested level. The proposal number is DMR 0807012.

Publications

Two publications in the past year reflect the vitality of the program.

M.G. Clerc, P. Cordero, J. Dunstan, K. Huff, N. Mujica, D. Risso, & G. Varas, "Liquid-solid-like transition in quasi-one-dimensional driven granular media", Nature Physics 4, 249 - 254 (2008). This prominent publication involves three interns in the program. Huff worked on this project in its early stages as an intern from Chicago. Varas and Dunstan were interns in Chicago before working on this project.

Luka Pocivavsek, Robert Dellsy, Andrew Kern, Sebastian Johnson, Binhua Lin, Ka Yee C. Lee, and Enrique Cerda, "Stress and Fold Localization in Thin Elastic Membranes" Science, 320 912-916 (2008). This project was driven by Pocivavsek's desire to explain lipid monolayer buckling via continuum mechanics. He used his internship with Prof. Cerda in Chile to develop the idea, then returned to Chicago to explore its experimental implications with the help of Chilean intern Sebastian Johnson.

Other publications resulting from intern projects in 2007-2008

D.L. Chen, L. Li, S. Reyes, D.N. Adamson and R.F. Ismagilov "Using three-phase flow of immiscible liquids to prevent coalescence of droplets in microfluidic channels: Criteria to identify the third liquid and validation with protein crystallizationm," Langmuir, 23, 2255 (2007).

S.L. Frey, E.Y. Chi, C. Arratia and K.Y. Lee, "Condensing and Fluidizing Effects of Ganglioside GM1 on Phospholipid Films," Biophysical Journal, 94 3047-3064 (2008).

X. Cheng, G. Varas, D. Citron, H.M. Jaeger and S.R. Nagel, "Collective behavior in a granular jet: Emergence of a liquid with zero surface-tension," Phys. Rev. Letters 99 188001 (2007).

V. Romero, T.A. Witten and E. Cerda, "Multiple Coiling of an Elastic Sheet in a Tube" Proc. Roy. Soc. A doi:10.1098/rspa.2007.0372 (2008) ...(2008).

Victor Romero, Enrique Cerda, T A Witten and Tao Liang "Force focusing in confined fibers and sheets" Journal of Physics D: Applied Physics 41 132003 (2008).

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