Abstracts for the Tiered Mentoring Poster Session 2011
1) Jean-Pierre Iskandar
a) Brightly colored integuments are thought to function primarily in communication, both to
conspecifics and heterospecifics. In birds, feather colors are generally classified as either
pigment-based or structural. The latter are often characterized by intense gloss arising from the
structuring ordering of feather materials. Indeed, many pigment-based feathers are also glossy;
however, how pigments and structure interact to produce these effects remain poorly
understood. We therefore combined diffuse and specular UV-vis reflectance spectrometry to
quantify the spectral properties that differentiate glossy and matte red colors, as well as light
and scanning electron microscopy to identify the morphological basis of such differences. Glossy
feathers showed fourfold specular-to-diffuse reflectance ratio (glossiness), twice that of the
control matte group. Further, these reflectance differences were concentrated in the red
portion of the visual spectrum. Though surface properties of feathers of both groups were
similar, glossy feathers had larger barbs with a flattened and homogeneous planar morphology,
which are consistent with the expectations for a glossy reflecting surface. Our results therefore
indicate that glossiness in pigment-based colors can be quantified and is a result of consistent
morphological changes to the feather barbs. In the future, we expect use transmission electron
microscopy to identify differences at the nanostructural level that may also contribute to
enhanced gloss.
2) Jonathan King
a) Projects that I worked on this summer encompassd the field of robotic prosthesis. Specifically I
focused on biomimetic controller types for the robotic prosthesis. The three main projects that I
worked on are forces during mass pick up, human adaptive tracking on a given track, and
proportional and biomimetic controllers comparisons. For the forces during mass pick up, a
human ,using their own hand, would lift a mass while a prosthesis was connected using surface
EMG electrodes doing the same task. Forces were recorded and compared for how the
prosthesis reacted compared to the human. The human adaptive track had humans use a pinch
motion to follow a track with a random spring creating resistance between their fingers. The
prosthesis was also given the same test with different gains using a designed contoller.
Overshoots and RMS error were used to compare the data. The proportional and biomimetic
controller comparison used human data input with prosthesis data output to compare two
different controller types.
3) Laura Clark
a) The large branchiopods (clam shrimp, fairy shrimp and tadpole shrimp) are a group of animals
that display a wide range of mating systems, including hermaphroditism, androdioecy, and
dioecy. Androdioecy is a rare mating system thought to be a brief transitional phase between
dioecy and hermaphroditism. However, in this group, androdioecy is common and relatively
stable. Several models have been developed to explain this pattern. A model constructed by
Pannell (1997, 2002) predicts that the likelihood of male invasion into all-monogenic (a
hermaphrodite capable of producing only hermaphrodites when self-fertilizing) populations will
be density dependent. In low hermaphrodite densities, males will be less likely to establish a
presence in the population than if there were high hermaphrodite densities. In the
overdominance model (Otto et al. 1993, Pannell 2008), amphigenic hermaphrodites (a
hermaphrodite capable of producing males via self-fertilization) could invade all monogenic
pools as long as the level of purging was not high enough such as to allow them to be more fit
than the amphigenics.The overdominance and metapopulation models are being tested with
multigenerational experiments. Multiple tanks of all monogenic populations of Eulimnadia
texana have been established and then subjected to invasions by either males or amphigenic
hermaphrodites in small quantities to mimic natural patterns of migration. If males cannot
invade, that would suggest that the predictions of the overdominance model are correct. If both
males and amphigenics invade successfully, then support would be provided for the
metapopulation model in which males and amphigenics provide relief from inbreeding
depression.
4) Stephen Callow
a) Microbiologically induced corrosion (MIC) is one of the most common forms of corrosion attacks
on infrastructures. Many case studies and reports have been documented on MIC, yet little is
known about the dissolution mechanisms and the relationship between metal substrate and
forms of different bacteria in biotic environments with corrosion processes. Traditionally, MIC
has been characterized in static conditions or in a simple electrochemical cell. However, such
experiments do not take into account the evolution of the interfacial processes in flow
conditions. To simulate and quantify the mechanisms and processes occurring at the interface
electrolyte/metal substrate, it is necessary to characterize the evolution of corrosion products
and biofilm formation and its relationship with corrosion under flow conditions.
b) A proposed flow chamber design developed to create consistent laminar flow across the metal’s
surface provides accurate and reproducible results for MIC study. This unique chamber, coupled
with pH sampling and real time electrochemical measurements will allow in-situ monitoring and
quantitative analysis at the film-metal interface. The proposed Electrochemical Impedance
Spectroscopy and open circuit measurements yield results to develop an understanding of the
mechanism by which MIC occurs and the influencing factors on progression.
5) George Voros
a) Geckos have been of particular interest in the biological and engineering fields due to their
exceptional adhesion ability on various substrates. Their ‘stickiness’ can be attributed to the
setal adhesion via use of van der Waals forces. Many geckos possess setae, which are
microscopic hair-like structures located on the ventral side of their digits. The study of setal
adhesion has been extensively researched at microscopic levels, but there is little focus on
behavioral aspects and the biomechanics at the organismal level. One such behavioral feature is
active digital hyperextension: the peeling of their toes from the distal end to proximal. In this
study we predict a correlation between the ability to hyperextend, substrate roughness and its
effect on performance in sprint speed. For this experiment, we hypothesize that geckos with
greater capabilities of hyperextension exhibit no significant difference in sprint speeds across
varying substrate roughness (smooth to rough) while geckos with lower capabilities of
hyperextension exhibit a significant difference in sprint speed across varying substrate (smooth
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to rough); we predict that the sprint speeds of geckos with a lower capabilities of
hyperextension will decrease as substrate roughness increases.
Sarah Kay
a) I will present on the thermal effects on rice cut grass ( Leersia orydoides) over a hydrology
gradient. The specific aspects looked at were plant height, weight, and chlorophyll content by
measuring absorbance.
Vrushti Patel
a) Growth of Very Fine Cyanoacrylate Nanofibers on Electrospun Fiber Mats - Electrospun
superhydrophobic nanofiber mats can be used in oil-water filtration. Superhydrophobic
nanofibers are electrospun on the surface of the filter media and when challenged by an oilwater mixture, the water is rejected at the surface of the media while the oil passes through.
However, small water drops present in the emulsion manage to pass through the fiber. Previous
work has been done on growing very fine cyanoacrylate nanofibers on the structure of existing
fiber media. In this work, cyanoacrylate nanofibers were grown on electrospun
superhydrophobic nanofibers and the water contact angle was measured before and after to
determine if the fine cyanoacrylate nanofibers affect the superhydrophobicity of the surface.
Kranthi Kumar
a) Precision Control of Stepper Motor - A stepper motor is an electric motor whose movements
along a revolution are divided in to steps. These steps are a patters of current which enable the
rotors inside to move accordingly. Depending on the number of steps in the each revolution the
motor can be precisely controlled, in both clockwise and anticlockwise directions. Such precision
enables to design very specific set of motion control applications like robotic arm control,
navigating in precise environments and for slow injection using a syringe. Our task was to
interface a stepper motor to a micro-controller for real time precision control. The stepper
motor used in the experiment was taken from a Syringe pump which injected precise amount of
liquid from the syringe, to make this viable the circuit was designed using two H-bridges. The
signals to control the motor were sent using a micro-controller. Corresponding analysis was
done on the how the stepper motor behaved as with respect to different signal generated from
the micro-controller.
Annmarie Abeyesekera
a) Euhrychiopsis lecontei (milfoil weevil) is used as a bio-control for the invasive Eurasian
watermilfoil (Myriophyllum spicatum). The weevils observed in eastern North America and
western North America were thought of as two different species but are now treated as one
species. The objective of this research is to study the association between the two different
species by means of DNA extraction and analyzing the obtained data.
Dakota Piorkowski
a) Orb-weaving spiders are intriguing model organisms with which to study adaptive foraging
strategies (changes in foraging behavior in response to environmental cues that increase
fitness), because they recycle and rebuild their webs daily. We attempted to evaluate how the
orb-weaving spider Argiope trifasciata alters the size, structure, silk investment, and mechanical
performance of its web over a period of starvation. To do this, we measured webs and collected
samples of silk threads of spiders housed in individual cages in a greenhouse. On each spider’s
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first full day spent in a cage, we systematically assigned it to one of two treatments based on its
mass; on this day one group of spiders received one meal consisting of cricket(s) (Acheta
domesticus) totaling 50% of the spider’s mass (“fed” treatment), while the other received no
meal (“starved”). We measured and sampled from each spider’s web on the 3rd, 5th, 7th, and 9th
day spent in its cage. Using day 3 as a baseline, we evaluated the percent change in web
capture area, silk volume, mesh width (space between consecutive capture spirals), and
“stickiness” (amount of energy required to detach from a capture spiral thread) on days 5, 7,
and 9, and compared the pattern of changes exhibited by fed versus starved spiders. We plan to
analyze these data using an estimate of change in body condition as a covariate, and seek to
interpret our results in the contexts of the variation in life history stage among our spiders, as
well as previous studies evaluating the feasibility of adaptive foraging strategies relative to
environmental stochasticity.
Kirsten Schulte
a) I will talk about the KUKA robot, spine testing, and the principle of super position.
Nancy Cross and Tim Sullivan
a) We investigated the effects of surface water and wetting on gecko adhesion at the wholeanimal level. We predicted that treatment with water would interfere with shear adhesive force
and decrease the gecko’s clinging ability. We tested this hypothesis by performing shear
adhesion trials with a force rig using a glass plate substrate treated with three different water
conditions. We also altered the wetting condition of the adhesive toe pads of the gecko. In total
we used six treatment groups and measured repeatability of the treatment as the gecko
replaced its feet over consecutive steps. Our results support our hypothesis and show that
water does significantly affect shear adhesive force in particular environmental conditions that a
gecko may encounter in its native habitat.
Soha Gouilos
a) Testing the viability of PNA-mediated PCR clamping to detect recombination using a prokaryotic
test system - PNA-mediated PCR clamping was optimized to distinguish between four very
similar strains of E. coli. PNAs can be used to distinguish very similar genetic sequences as they
bind with extreme affinity, but are very specific and will not bind if the sequence differs by as
little as one base pair from the compliment of the PNA. Two PNAs have been designed to be
complimentary to two variable locations in what we have defined as our "wildtype" strain of
E.coli. Because each of the other three strains differ in the location of their SNPs, unique
banding patterns were derived for each and were sufficient to distinguish between the four
strains.
Steven Lombardo and Kristie Formanik
a) Genotype (G), environment (E), and their interaction (GxE) are known sources of phenotypic
variation. Recently, studies have focused on the consequences of shifting environmental
parameters on developmental outcomes. Recent studies have discovered interactions between
subsequent ontogenetic environments (ExE) on fish behavior and cognition. In this study, we
assessed genetic variation for cross-environmental responses in zebrafish morphology and
swimming performance. We reared 4 full sib zebrafish families (F) on a constant normal nutrient
diet for 60 days, a constant high nutrient diet for 60 days, and both combinations of nutritional
environments for consecutive 30 day periods (0-30 days high, 30-60 days normal; 0-30 days
normal, 30-60 days high). We then measured overall size (length and maximum depth) and
swimming performance (maximum body lengths s-1). While we found no effect of nutritional
environment on morphology, swimming performance was altered by an interaction between
subsequent nutritional environments (ExE), with high nutrient fish (days 0-30) achieving the
highest swimming velocity when switched to a low nutrient environment (days 30-60).
Furthermore, we find the quality of interactions between rearing environments varied across
families (FxExE). These results not only highlight the potential for environmental change to alter
physiological performance, but for selection to shape the most appropriate response.