are held on Tuesdays, 3:45-4:45pm in SB 110, unless otherwise noted. Meet
at 3:30 in SB 157 for refreshments (refreshments are available even on
Tuesdays with no seminar!). See Calvin's
Visitor Resources for maps and directions to the Science Building.
Schedules from previous
semesters:Fall 2003, Spring
2003, Fall 2002, Spring
February 4, SB010, with Engineering Dept.
Satellites and Rovers: Mars Exploration from Atmospheric Platforms
||Prof. Matt Heun,
Calvin Engineering Department
Materials and Devices: Studies using Superconductive Thin Films
Steve Remillard '88, founder and president of Agile
24, 3:40pm in NH276, with Math Dept.
and How It Is Used
||Dr. Jim Keener,
math professor, University of Utah
1, 3:30pm in SB010 with Biology
and Engineering Departments
out those hips! Engineering and Orthopedics
'86, orthopedic engineer at Zimmer,
Sand: Separation, Pattern Formation, and the Gas between the Grains
'02, grad student at Harvard-Smithsonian Center for Astrophysics
Physics and Circuit Applications of
Resonant Tunneling Diodes
|Dr. Robert Potter,
Fruits of Calvin's Twin Telescopes: Cool Images and New
May 7, in SB010, at 3:30, part of
Perspectives in Science Series
and the Tale of the Pale Blue Dot
Dennis Danielson, Professor of English, University of British
4: Between Satellites and Rovers: Mars Exploration from Atmospheric Platforms
Prof. Matt Heun, Calvin Engineering Department
To date, Mars has been studied exclusively from orbital and surface
locations, yielding a wealth of scientific data about the red planet.
However, there have ben several, less-publicized, attempts to develop
observation platforms that offer both a "birds-eye" view of
the planet, like satellites, and scientifically-driven mobility, like
rovers. These alternative atmospheric platforms include airplanes, gliders,
balloons, and airships. The political and technical challengs of designing
atmospheric platforms as well as the strengths and weaknesses of each
proposed approach will be discussed. And, details of a previous Mars balloon
development effort will be presented.
17: Nonlinear Materials and Devices: Studies using Superconductive Thin
Films. Dr. Steve Remillard '88, founder and president of Agile
A primer on superconductivity will be presented. Emphasis will be given
to the way in which many branches of fundamental physics are used in describing
superconductivity, including thermodynamics, electromagnetics, classical
mechanics and quantum mechanics. Elements from each of these branches
are used to explain the phenomenon of flux nucleation, whcih then leads
to microwave nonlinearities in the material. After introducing the idea
of microwave nonlinearity, we will look at how nonlinearities are measured
at microwave frequencies. A "back-of-the-envelope" calculation
will consider how well measurements with superconducting devices correspond
to what is known about flux nucleation.
Diffusion, and How It Is Used. Dr. Jim Keener, professor of mathematics
at the University of Utah. Dr. Keener is the author of Mathematical
Physiology, designated "Best New Title in Mathematics"
in 1998 by the Association of American Publishers.
Diffusion is one of the most important features of biological systems,
especially when combined with chemical reactions. In this talk Dr. Keener
will discuss some of the mathematical consequences of Fick's law of diffusion,
and how several biological organisms utilize these to facilitate their
existence. The examples he will describe include transport of oxygen and
carbon dioxide, quorum sensing by bacteria, and detection of filament
length by salmonella. (To understand this talk completely, one will need
to know a little bit, but not much, about ordinary differential equations.)
March 1: Check
out those hips! Engineering and Orthopedics Steve Meulink '86
Calvin BSE Graduate now working for Zimmer,
Inc. of Warsaw, IN
This presentation will be an overview of hip surgery and hardware, hip
design, materials and processes, and advances in minimally invasive surgery.
He will also talk about what it means to be a Christian engineer or medical
professional with general reflections of his college experience and subsequent
career in orthopedic engineering.
Shaking Sand: Separation, Pattern Formation, and the Gas between the Grains
Mason Klein '02, grad student at Harvard-Smithsonian Center for Astrophysics
but almost as fun. Typically in vibrated granular
media, particles separate by size, the largest rising to the top --
try it with a can of mixed nuts. But what happens when everything
is the same size? I will present recent work on mixing and
de-mixing in vibrated sand made of equally-sized bronze and glass
spheres. It turns out that density-based pattern formation depends heavily
properties of the surrounding air or other gas. There
will be pictures and movies of sand in action, as well as me trying
to explain what is going on in this system.
The Physics and Circuit Applications of
Resonant Tunneling Diodes Dr. Robert Potter, Knowles Electronics
of single barrier particle tunneling and the existence of quantized energy
states of a particle in a box (potential well) will be reviewed. Resonant
tunneling, which combines the ideas of single barrier tunneling together
with quantized states in a potential well will then be introduced.
tunneling diode (RTD) is a physical realization of such an ideal, abstract
resonant tunneling system, and it is usually made in semiconductor heterostructures
such as GaAs/AlGaAs or InGaAs/InAlAs. Some common devices structures that
employ narrow potential wells (~ 50 A) will be described along with the
device’s measured current-voltage (I-V) characteristic, which is
highly nonlinear and which has a region of negative differential resistance.
Fine structure that is observed in the I-V characteristics of a wide well
(~ 600 A) device, that can be attributed to virtual state scattering,
even at room temperature, will be presented.
growing several such RTD structures vertically, a device that has multiple
regions of negative differential resistance can be fabricated. These I-V
characteristics can be used to implement complex circuit functions that
have greatly reduced circuit complexity when compared to conventional
circuit implementations. The circuit applications of these multi-peaked
devices for achieving functions such as frequency multiplication, parity
bit generation, multi-level logic, and analog-to-digital conversion will
First Fruits of Calvin's Twin Telescopes: Cool Images and New
Science Professor Larry Molnar
Almost two years ago, Calvin College received money for a new 16 inch
telescope on the Science Building and a second one (to be operated remotely)
the Rehoboth Christian School in northwest New Mexico. This talk brings
subject up-to-date on how the construction has gone, what innovations
needed to make the project work, and what kind of cool images are now
obtained by even 100-level students. It will also present a series of
observations of the binary star system U Geminorum: a bizarre system in
one star, which has collapsed down to the size of the earth, spins around
normal star every four hours. A stream of material is pulled off of the
star and forms a disk around the collapsed star. Analysis of our own
observations adds to this story an understanding of the dramatic way in
the disk develops over time. This is a first taste of the opportunities
astronomical research upper class students will have from now on.
May 7: Copernicus
and the Tale of the Pale Blue Dot Dr. Dennis Danielson, Professor
of English, University of British Columbia.
Most of us have at some point heard the claim that Copernicus, by "dethroning"
earth from the center of the universe, “showed” that the Earth
and Earth’s inhabitants are cosmically not very special. This claim
is routinely extrapolated to function as a principle -- the “Copernican
Principle” -- according to which not only is Earth merely one planet
among many, but also the Milky Way is merely one galaxy among many, and
perhaps what we think of as the whole cosmos is merely one universe among
many. Moreover, this “principle” is enlisted to show that
science trumps religion: while religion wants to enthrone Earth-dwelling
human beings in the center of the universe, science authoritatively demonstrates
(in more ways than one) the “mediocrity” of our place. From
Fontenelle in the seventeenth century to Carl Sagan in the late twentieth,
Copernicus is thus used to bring down human pride, which supposedly stems
from our naive religious illusions. Unfortunately, this comic-book version
of the meaning of Copernicus is all but universally accepted by many educated
people, including some scientists, whose capacity to weigh evidence ought
to make them capable of a more well-informed, critical view. An effort
to attain such a critical view -- based on the exciting words Copernicus
and his followers, and on a measure of undogmatic careful thinking --
can revitalize our perception not only of Copernicus in his own age but
also of the interplay between science and metascientific assumptions today.