Natural Science Seminar - Abstracts Fall 2006
Sarah De Leiris
February 12, 2007
Coyote (Canis latrans) scat analysis in the
Narragansett Bay region of Rhode Island
Mentor: Dr. Lou Weber.
Abstract: Coyote (Canis latrans)
populations are growing in numbers throughout Rhode Island and New
England. Previous studies indicate that humans influence diet,
but the extent to which they affect game species and household pets has
not been determined. My objective was to determine the
composition of coyote diets in the island populations of Rhode
Island. Scat samples were collected from Aquidneck and Conanicut
Islands. The sample contents were separated into categories of
Hair; Bone; Plant; Insect; Feather; Other, and volume percentages were
calculated. The Hair category had the highest volume percentage
(52.6%), the Plant category had the next highest volume percentage
(26.0%), and all the other categories were below 10.0% volume.
Deer hair was present in 31.4% of the samples, and cat hair was found
in 10.0% of the samples. The data indicate that the influence on
coyote diets by the close proximity of humans is minor. There is
not enough evidence to show that a change in human behavior will affect
the coyote population size. Rhode Island residents should be
aware of the presence and habits of coyotes when allowing their pets
outside on their own.
Marie
Williamson
February 19, 2007
Urinary ergot
alkaloid excretion by beef heifers and cows grazing endophyte-infected (Neotyphodium coenphialum) tall fescue (Festuca arundinacea) pastures and hay.
Mentor: Dr. Victoria Collins
Abstract: Fescue (festuca arundinacea) is the
predominant grass in pastures at Warren Wilson College
farm. Fescue has a symbiotic relationship with a fungal
endophyte (Neotyphodium coenphialum)
that lives within leaf sheath cells and produces alkaloids. Ergot
alkoloids are responsible for fescue toxicosis, the symptoms that
cattle experience grazing endophyte-infected (E+) fescue.
Symptoms include vasoconstriction, decreased conception rates, and
decreased lactation. Measuring total ergot alkaloid
content in urine is being developed as a diagnostic tool for fescue
toxicosis. Urinary analysis is useful because it provides a
reliable snapshot of current alkaloid consumption by
cattle. The objective of this study was to compare urinary
ergot alkaloid levels from cows and heifers grazing E+ pasture. A
second objective was to compare urinary ergot alkaloid levels from cows
and heifers grazing E+ pasture to cows and heifers consuming fescue
hay. Samples were obtained from cows and heifers grazing E+ fescue in
Dogwood, Charlie’s, and Daisy Hill pastures in September 2006.
Samples were also obtained from cows and heifers consuming fescue
hay. A competitive ELISA test kit, manufactured by Agrinostics
Ltd., was used to determine ergot alkaloid levels. No significant
difference ( p= 0.4048) of alkaloid excretion was measured between cows
and heifers, allowing the data for all cattle to be pooled. There
was no significant difference (p=: 0.8567) in alkaloid excretion in
Dogwood, Charlie’s, and Daisy Hill pastures or when cattle consumed
hay. The average alkaloid excretion by cattle grazing E+ pastures
was 18.21 ng alkaloid/ mg creatinine. Alkaloid excretion in the
fall corresponds to low fescue toxicity levels in published data.
Betsy Kain
February 19, 2007
Coloration and
Courtship Behavior in Male Guppies Treated with Estrogen
Mentors: Dr. Jeff Holmes and Dr. Robert Eckstein.
Abstract: Fish species around
the world are being identified as intersex, which is the presence of
both male and female gonadal features in one individual. One
explanation for the presence of intersex fish is endocrine disrupting
chemicals (EDCs) in our aquatic ecosystems. Steroidal estrogens
such as 17-a-Ethynylestradiol (EE2), which is derived from
contraceptive pills, are designed to be extremely potent and have the
greatest endocrine-disrupting capability of all EDCs. This study
was designed to assess the effect of EE2 on the development of male
coloration and the expression of male mating behaviors in guppies, a
fish in which both are well characterized. Groups of male guppies
were exposed to approximately 10, 50, or 200 ng/L of EE2 over the
course of 78 days. Then, individual males were paired with
females and the following four courtship behaviors were observed:
sigmoid display, gonopodial swing, gonopodial thrust, and biting
cloaca. The average number of total behaviors per fish per day
for each treatment group was statistically analyzed using ANOVA.
The highest dose group had significantly fewer behaviors than the
control group, with a P value of 0.007. Color intensity was rated
for all males by eight different observers. Four out of the seven
fish in the control tank were ranked as most intensely colored compared
to the fish in the other tanks. These results suggest
that exposure to EE2 may result in reduced male coloration and
behavioral changes that might be expected to have a negative effect on
the reproductive fitness of males exposed to this environmental
contaminant.
Neal Maker
February 26, 2007
Basal area and
form class relationship for small diameter Loblolly pine (Pinus taeda) in the North Carolina
piedmont
Mentor: Dr. Amy Boyd
Abstract: Demand for
value added forest products and an abundance of unused small-diameter
timber have created interest in structural uses for small diameter
timber. Research on structural roundwood is focused on the
western United States because of thinning occurring there for fire
reduction, but small-diameter timber is also left unused in the
southeastern United States after pre-commercial thinning. Several
factors determine the usefulness of timber for small-diameter
structural applications, including timber taper. This study was
an attempt to determine if a relationship exists between tree taper in
a stand in the southeast and the stand’s density. A relationship would
help landowners manage for taper of standing, small-diameter
timber. Basal area (a measure of stand density) and average
Girard’s form class (a measure of tree taper) were measured on
thirty-five plots of 12 to 18 year old loblolly pine in the Duke Forest
on the North Carolina piedmont using a Spiegel-Relaskop. No
significant correlation was found between basal area and form class
(r2=0.070). This is surprising because a correlation does exist
for mature Loblolly pine. One possible explanation is that
variation in taper due to early dominance development in loblolly is
overshadowing the density-taper relationship.
Todd Steven
Boera
March 5, 2007
Agricultural
Lime as a
Control Method for Leaf Cutter Ants (Atta sp.).
Abstract: Leafcutter ants (Atta
sp.) represent a problem to farmers throughout Central America. It is
not uncommon for Atta to destroy an entire citrus or cassava plot in
just one evening of work. Atta is considered to be the dominant
herbivore in the tropics, with the amount of vegetable matter being cut
estimated at 12-17 percent of annual leaf production. The current and
most common control method employed throughout Central America is the
use of a chemical insecticide known as lorsban. Farmers complain about
the expense of this product as well as the human and environmental
health problems with which it is associated. Organic farmers in San
Pedro Columbia, Belize often experiment with alternative methods to
control Atta populations. The focus of this study was to determine if
agricultural lime as a treatment would produce a significant difference
in activity amongst three different hives. Results showed that there
was a significant difference (p-value=.00004) from the treatments.
However, the significant difference was due to one hive (p-value=
.0000003) which caused the large difference amongst all data. The
implementation of agricultural lime as a control method is recommended
for Central American farmers to decrease Atta activity.
Laura Foulke
March 5, 2007
Ground Water
Analysis of Formaldehyde at the Edges of Cemeteries in Buncombe County,
NC.
Mentor: Dr. Victoria Collins
Abstract: Embalming of human
remains is necessary when burial or refrigeration is not performed
within 24 hours. Embalming currently uses about five liters of a 14-17
% formaldehyde solution and is common practice in the United States for
aesthetics. EPA classifies formaldehyde as a hazardous substance,
hazardous waste, and a possible human carcinogen, yet approximately
1,325,000 liters (350,000 gallons) are legally buried by the funeral
industry each year. No evidence of prior research on formaldehyde
concentrations in and or around cemeteries was found, but some articles
noted concern that formaldehyde might migrate in groundwater due to its
high water solubility. The objective of this study was to determine the
formaldehyde concentrations in ground water at the edge of three
cemeteries from soil and water samples. Both types of samples were
collected from each cemetery twice between November 2006 and February
2007 and analyzed using EPA method number 8315 A, which uses High
Performance Liquid Chromatography to detect a 2,4
dinitrophenylhydrazone derivative of formaldehyde at 360 nm wavelength.
The determined detection limit was 25mM in soil and 0.5mM in water.
Formaldehyde was detected in the water at the two with streams and in
soil samples at all three. Formaldehyde concentration was higher
in soil than in water and was not related to depth, rainfall, or age of
the cemetery. The data suggests that formaldehyde is persistent in
soil, but not in water. Future research of other cemetery contaminants
such as lead and arsenic and of microbial activity in cemetery soil are
recommended.
Rebecca
DaVanon
March 12, 2007
The Response of
Native Grasses to Controlled Burning and Herbicide Application on a
Native Grass Restoration Site
Mentor: Dr. Amy Boyd
Abstract: Grassland
communities are threatened by the encroachment and establishment of
woody broadleaf shrubs. Frequent burning has traditional
maintained grass dominance, but a decrease in fire size and frequency
in the last 150 years has resulted in an increase in shrub size and
density. Frequent controlled burning has been shown to decrease
broadleaf cover as long as shrubs have not already become
established. Selective herbicide application has been shown to
suppress broadleaf competition. The Christmas Tree Hill
Restoration site grass community has experienced competition with
invasive species since it was established. The objective of this
study was to evaluate controlled burning and herbicide application as
management techniques for species cover of native grasses at the
Christmas Tree Hill Restoration site. Plots on site received
treatments of either controlled burn, herbicide application,
herbicide/burn, or control. Fifty-two plots were analyzed
for presence and dominance of study group species (broomsedge,
Indiangrass, total species) and percent species cover was
determined. The dominance of broomsedge was significantly higher
(p=0.0292) for herbicide/burn plots than for control plots.
Treatment type was insignificant for presence and dominance in all
other study groups. Broomsedge accounted for half of the presence
of native grasses on site (28% presence broomsedge/56% total species
presence). The Indiangrass presence (p=0.0530), with more
replication, may indicate a difference between treatment type
received. A positive response for broomsedge to fire and to
herbicide application on broadleaf species corresponds to published
data. Further study is needed to determine broomsedge’s effect on the
site’s native grass community.
Sage
Brodersen
March 12, 2007
Managed Native
Grasses and Oldfield Insect Communities
Mentor: Dr. Amy Boyd
Abstract: Currently the
grassland biome is being threatened by introduced invasive plant
species. It is unknown how these introduced plant species will affect
the wildlife associated with grasslands. This is a particularly
important issue for oldfield insects because they are the most abundant
form of wildlife in the grassland ecosystem. The objective of this
study was to determine the effects of managed native grasses on the
diversity and composition of oldfield insect communities. Three
different sampling areas were used with 30 insect samples and 15 plant
biomass samples taken in each. Insects were identified to the order and
family level. The three sampling areas consisted of one that is managed
for native grasses, one that was cut and then left unmanaged, and one
that is managed for turf forming grasses. This method of sampling is
pseudoreplication because I only had one replicate for each type of
sampling area. Analysis was done to determine order and family
richness, and a Simpson’s diversity index was used to determine order
and family diversity. Discriminant analysis was used to find the
differences in the insect orders across the three treatment areas. The
native grass area showed the highest richness and diversity. In
addition more predatory and parasitic insects were found in the native
grass area while more pest type species were found in the unmanaged
testing area. If multiple sampling areas were used yielding the same
results that I found here, this study would have major
implications. These implications are that in losing the
biodiversity of the grasslands plants we are also losing biodiversity
in the insect communities associated with them. In addition, the
presence of the parasitic and predatory insects in the native grass
area suggests that borders of native grassland plants could be a
helpful tool in agricultural systems.
Will Lyons
March 26, 2007
The effect of
efficient microbes (EM)ä on compost
Abstract: Compost builds soil
quality by increasing organic matter, providing plant nutrients and
hormones, and serving as an innoculum of beneficial organisms.
The successful production of high quality compost requires careful
management of physical, chemical, and biological characteristics of the
pile: moisture, temperature, aeration, C: N ratio, and microbial
community structure. While many compost systems simply use
available material some use inoculants for starting or accelerating the
decomposition process. A Japanese professor, Teruo Higa, invented
one such product known as Effective Microorganisms. My objective
was to determine whether inoculation with Effective Microorganisms
during pile construction significantly altered any physical, chemical,
or biological processes during the first 75 days of composting.
All piles were constructed from dairy manure and straw. Two piles
were inoculated with Efficient Microbes™ (EM). All piles were
aerated weekly over the study period from November 1, 2006 through
January 15, 2007. Temperature was monitored three times a
week. Samples for moisture, pH, and C:N ratio were taken
weekly. Microbial community structure was examined using
phospholipid fatty acid (PLFA) analysis to measure the % bacterial
fatty acids and % fungal fatty acids present in the piles. The
use of EM™ did not affect any of the measured parameters. The
project received funding from the North Carolina Academy of Sciences
through a Yarborough grant.
Aaron
Malenke
April 6, 2007
Metalloestrogen
concentrations in the blood of American alligators, Alligator mississippiensis, in two Florida lakes.
Metalloestrogens are inorganic xenoestrogens that bind to and activate
estrogen receptors. An increase of estrogenic activity in
American alligators has been linked to reproductive disorders and can
override temperature-dependent sex determination. The objective of this
study was to determine if metalloestrogen blood concentrations differ
between American alligators living in two Florida lakes: Lake Woodruff
and Cape Canaveral. Lake Woodruff is a national wildlife
preserve, while Cape Canaveral borders the Kennedy Space Center, a
possible heavy metal contamination source. Blood samples were
dissolved with 70% nitric acid and 30% hydrochloric acid, and analyzed
for aluminum, antimony, cadmium, chromium, copper, lead, nickel, tin,
and vanadium using an inductively coupled plasma emission
spectrophotometer. Aluminum and vanadium standards were not
testable due to possible contamination. Antimony, copper, and
nickel concentrations were below detectable range of 10 ppb, 50,000
ppb, and 20,000 ppb respectively. Using a standard t-test
analysis, cadmium, chromium, lead, and tin concentrations were not
significantly different (p < .05 considered significant) between the
two lakes. Further studies can treat alligator eggs with
metalloestrogen concentrations similar to those found in blood from
Cape Canaveral alligators. These studies could determine the effects of
heavy metals on alligators at Cape Canaveral
Michael
Hutchison
Weed Seedbank
Assessment in Four Farm Fields
April 2, 2007
Abstract: Weeds have been
interacting with humans since the advent of agriculture, and have
evolved and adapted to many disturbance regimes (Buhler, 1999).
However, weeds also provide beneficial habitat, and provide important
soil forming processes (Altieri, 1981; Liebman, 1981). A crucial
component of weed- crop interactions is the pool of dormant seeds
existing in the soil, called the weed seed bank (Roberts, 1981).
The objective of this observational study was to quantify the density,
composition and diversity of the germinable fraction of the weed seed
bank in four crop fields at Warren Wilson College. Four different
treatments in the crop rotation were used to control disturbance.
Soil texture was controlled for with three treatments in Iotla and one
treatment in Dillard series. A randomized transect sampling
method was used, based on the Hayashi species-volume curve (Hayashi and
Numata, 1975). Fifty five 0.5 cm samples were taken at each
location, and bulked. Samples were spread on potting soil and
placed in conditions conducive to germination according to Gross et al
(1990). Seedling were counted and removed upon identification to
species. Twenty two species were identified. Estimated weed
seed per hectare ranged from 3.14 x 109 in Ballfield, to 7.8
x 107 seed/ha in Northups. It was determined that
primary tillage is most important seed bank forming factor. While
a simple preliminary study, seed bank analysis is an important aspect
of crop monitoring.
Travis
Briggs
Cold
Tolerance and Range Expansion of
Upside-down Jellyfish (Cassiopea
xamachana)
April 9, 2007
Abstract:
Upside-down
Jellyfish (Cassiopea xamachana), once
limited to waters off the Florida Bay, recently began a northward
expansion. Presently, Cassiopea
populations have become numerous as far north as Sarasota
Bay, inhabiting shallow mangrove bays and lagoons with mud and sand
bottoms. The objective of this project
was to determine why Cassiopea are
currently expanding northerly along the gulf coast of Florida. Initial cold tolerance tests were conducted
to establish that Cassiopea’s pulse
rate is affected by water temperature. Pulsation in Cassiopea
allows for effective exchange of dissolved oxygen, the
ability to clear tentacles of sediment, and the means for locomotion. Further cold tolerance tests showed that
when Cassiopea reached a critical
temperature (12-14°C) pulsation stops. A second set of cold
tolerance tests
found that Cassiopea could survive a
22-24 hour exposure to critical temperatures.
An extended exposure to critical temperatures, beyond 22-24
hours,
resulted in 100% mortality. In 1994, The
Mote Marine Laboratory (MML) began recording water temperature data
from New
Pass in Sarasota, FL. The results from
the cold tolerance tests were compared to historical temperature
records collected
by the MML to determine that there was no apparent correlation between
changes
in local water temperatures and the presence of Cassiopea.
John
Andrew Wagner
April 9th, 2007
Effects of
Imidacloprid on Eastern Hemlocks Infested by the Hemlock Wooly Adelgid
Abstract: The hemlock wooly
adelgid is currently devastating the hemlock forests of the eastern
U.S., and much research has involved finding information about the pest
and possible means of control. Chemical therapy is the only
currently effective method for adelgid control, and biological control
is not working. Imidacloprid is the most widely accepted chemical
treatment due to its relatively low toxicity to vertebrate species, but
there is no reliable information regarding the effects of Imidacloprid
to plants. Monoterpene composition is shown in many studies to
vary in the presence of environmental stresses such as predation and
drought. The objective of this research was to use monoterpenes
to study possible effects of Imidacloprid therapy in relation to
natural defenses in eastern hemlock. In December, thirty six
composite needle samples were collected from eastern hemlocks in the
Berea stand at Warren Wilson College. All trees used in this
study were infested by hemlock wooly adelgid. These samples were
extracted, and the extracts were analyzed by gas chromatography to
measure the composition of the terpene components. Peak
enhancement was simultaneously performed to identify nine of the
terpene components in the mixture. Mood’s non-parametric test was
performed on the percent composition of 18 compounds from the terpene
extract. One unidentified compound was the only component with a
statistically different percent composition in treated versus
non-treated trees. Because the only affected component in the
terpene extract was unidentified, no judgments can be made as to if the
effect is deleterious or beneficial to hemlock health. However,
there is presently no apparent effect of Imidacloprid on the immune
health of eastern hemlock.
Daniel
Dayton
April 16, 2007
Comparison of the
Microbial Composition of the Three Compost Systems at Warren Wilson
College Using Phospholipid Fatty Acid Analysis
Mentor: Dr. Vicki Collins
Abstract: A critical part of a
healthy soil community is a diverse microbial population. Soil
microbes include bacterial and fungal populations. ( These organisms
perform numerous beneficial activities that help to stimulate healthy
plant growth. These activities include immobilization of nutrients with
in the biomass, production of compounds that increase soil aggregation,
active competition with disease-causing organisms, and increased
nutrient and water uptake for plants through mutualistic
relationships)omit. Compost is used in many sustainable
agricultural settings as a means to promote healthy soil microbial
populations. Compost refers to the aerobic decomposition of
organic matter by microorganisms under controlled conditions.
There are many influencing factors in the production of compost
including: carbon to nitrogen ratio, temperature of decomposition, pH,
moisture and scale. At Warren Wilson College, there are three
main composting systems in place. Two of the three, Farm and
Garden, are passive windrow systems that use passive aeration and long
curing time to finish the compost. The third, Recycling compost,
is an in-vessel, agitated aeration system that uses a large rotating
drum to constantly aerate the compost greatly speeding the initial
decomposition to 3-5 days. This compost is then aged
approximately 6-8 months before it is incorporated into the soil.
The objective of this project was to conduct an initial study of the
microbial composition of the finished compost produced by each of these
three composting systems. The microbial composition was compared
by calculating the fungal: bacterial ratio for all three
treatments. A second(sub-)objective was to observe if a
correlation existed between temperature and fungal: bacterial
ratio. Phospholipid fatty acid analysis (PFLA) was used to
observe the microbial makeup of the compost. PFLA is a process of
extracting the membrane lipids from the compost, hydrolyzing the
phospholipids to fatty acids and quantifying the products, in this case
with a Gas Chromatograph using Flame (no caps) Ionization
Detection. The results produced) no significant differences were
found between treatments for between any individual fatty acid or the
total fungal: bacterial ratio after comparison using non-parametric
tests. The effect of temperature on microbial composition was
also inconclusive with a correlation value R2 of 0.2671. The
fatty acid profiles for all three composting systems were highly
variable. This indicated that the composting process is highly
complex and highly variable within each pile.
Kathryn Kuehl
April 16th, 2007
Olfactory
stimulation by lavender (Lavendula
angustifolia)
essential oil and behavior of kenneled dogs (Canis familiaris).
Mentor: Dr. Robert Eckstein
Abstract: A common trait of
the domestic dog is a keen sense of smell. Studies on different
mammals have shown that olfactory stimulation is connected with
behavior, emotions, and health. In particular, lavender scent has
been shown to have a sedative effect. This study was designed to
compare the behaviors of dogs confined in a boarding kennel with
behaviors while exposed to olfactory stimulation of diffused lavender
essential oil. Behaviors for each dog were recorded at five
minute sampling intervals using a scan- sample technique.
Behaviors were recorded for two hours, the olfactory stimulation was
introduced, and then after 30 minutes, behaviors were recorded again
for two hours. For each sample point, a dog’s posture was
recorded as sitting, standing, jumping, resting or sleeping, and its
behavior was also recorded as either vocalizing or not
vocalizing. For each dog, the proportion of sampling intervals
performing a behavior during the control period was compared to the
proportion during the scent treatment using either a paired t-test or a
Wilcoxon matched-pairs signed-ranks test. A significant
difference of proportions was shown for all behaviors (p< 0.0003),
with sitting, standing, jumping, and vocalizing being reduced, and
resting and sleeping increasing with olfactory stimulation. These
results suggest that olfactory stimulation does affect the behaviors of
kenneled dogs. This information could be used to look at the use
of olfactory stimulation with other scents, for treatment of dogs with
specific behavioral issues, or in other settings, such as shelters or
veterinary clinics.
Dietrich J.
Blum
April 23, 2007
Effect of Citrate
on the Phytoremediation of Pb by Barley (Hordeum vulgare L.)
Mentor: Dr Victoria Collins
Abstract: Phytoremediation, the
use of plants to remove, degrade, or control the movement of toxins in
soil or water systems, is an emerging technology in the area of
environmental clean up and protection. This study focuses on the use of
barley (Hordeum vulgare L.), a
high biomass hyperaccumulator, to remove lead (Pb) from contaminated
soil with the amendment of citrate. Citrate is a naturally occurring
low molecular weight organic acid. The objective of this experiment was
to determine the effect of citrate on the uptake and translocation of
lead to the harvestable portion of barley. Concerns over the mobility
of lead into the water table were addressed by analysis of the soil
leachate. Total Pb concentration in the soils was determined by nitric
acid extraction. Mobile Pb in the soils was determined with an acetic
acid extraction buffered to pH 5.5. There were 10 replicate pots with
11 barley plants per pot grown in the greenhouse for each of the four
experimental conditions. Treatments included the presence / absence of
Pb contaminated soil and the presence / absence of an amendment of
0.0225 moles of citric acid per pot. Pb concentration in barley shoots
from plants grown in contaminated soil was found to average 191.6 ppm
with the citrate amendment compared to 3.4 ppm without the amendment, a
significant difference (p= 1.56 E-06). Plants grown in citrate
amended, Pb contaminated soil produced roots with an average Pb
concentration of 129.4 ppm, a significant difference (p= 0.016), when
compared to the shoots grown in the same soil with the citrate
amendment. It was found that citrate mobilized Pb into the leachate of
amended contaminated soil with and average of 18.0 ppm compared to 0.0
ppm in leachate from contaminated soil without the citrate
amendment, a significant difference (p= 6.0 E -4). Citrate was found to
be an effective chelator moving Pb both into barley plants and within
the barley plant from the root into the shoot. Citrate was found to
move Pb into soil leachate. Citrate while useful for enhancing Pb
uptake and translocation may cause unwanted movement of Pb within the
soil profile and into the water table.
James Blair
April 23, 2007
Agricultural Labor
Issues and Market Potential Of Latino-owned Businesses in Western North
Carolina
Mentors: Dr. Laura Lengnick and Laura Kirby
Abstract: In Western North
Carolina (WNC) the overall population has grown 17% from 1990 to
2000. One noticeable trend is the growing Latino population,
within the same period it has grown over 520%. An assessment of
WNC regional food system suggests that the Latino community has an
important role. Latinos overlap with the food system as a growing
percentage of new farmers and are the largest source of farm labor in
the region. In addition the potential exists of new and growing
markets for local foods within Latino-owned restaurants and
tiendas. The objective of this study is to determine market
potential of locally grown food in Latino-owned businesses and to
identify barriers and labor issues among Latino farmers and farm
workers. In order to meet this objective seven Coalicion de Organizaciones
Latino-Americanas member organizations that work closely with
the Latino community were surveyed about potential markets and labor
concerns. The most significant labor concerns focused on lack of
training/protective equipment and pesticide exposure and workers
undocumented status. Latino farmers also faced lack of
agricultural resource support and difficulties due to lack of community
support and available markets. Although results estimated
that
over 50 tiendas and 75 restaurants are operating in the seven counties
surveyed there appeared to be no interest of local sourcing. With
the appropriate outreach the growing number of Latino-owned businesses
could be a viable market for farmers. In conclusion this study
suggests the need for a more inclusive and supportive environment for
Latino farmers and farm workers as their influence on the farming in
the region continues to grow.
George Keel
April 30, 2007
Observation and
analysis of light curves of eclipsing cataclysmic variable IP Pegasi
Mentor: Dr. Donald Collins
Abstract: IP Pegasi, an
eclipsing cataclysmic variable star, consists of a white dwarf and a
red dwarf in binary orbit. The high-density white dwarf accretes
matter from the red dwarf by means of an accretion disk. The red
dwarf eclipses the white dwarf every 3.8 hours causing a large decrease
in luminosity every cycle. Occasionally the system goes into
outburst due to accretion disk instabilities resulting in an overall
luminosity increase. Data was obtained from the American
Association of Variable Star Observers (AAVSO) during outbursts. Data
was also obtained through an 8-inch aperture Schmidt Cassegrain
Telescope with a Meade DSI-Pro CCD camera at Warren Wilson
College. The light curve during the outburst displays a high
luminosity midway between narrow eclipses. In the quiescent state
the peak intensity occurs just before the eclipse begins, and the
eclipse is no longer symmetrical. It is believed that during
outburst the brightest region lies in the center of the accretion
disk. As the outburst progresses the bright region disperses
throughout the accretion disk. During the quiescent state the
brightest regions of the system are the red dwarf, the white dwarf, and
the hot spot on the perimeter of the accretion disk. During quiescence
the hot spot contributes a much larger proportion of the luminosity of
the system.
Edwin Self
April 30, 2007
Nitrate leaching
from manure compost and its effects on groundwater quality
Mentor: Dr. Mark Brenner
Abstract: Management strategies
for controlling waste are important to minimize the amount of
nitrogenous compounds lost to the groundwater. One of these
methods is composting of manures. WWC farm composts all of the
waste collected from the winter feeding of cattle and the hog and
chicken operations. The purpose of this study was to determine if
the composting of manure solids on the Warren Wilson College Farm was
contributing excess nitrates (>10mg/L) to the groundwater.
Groundwater monitoring wells were constructed and placed up gradient
and down gradient of the composting windrows. Wells were sampled
weekly for six weeks and analyzed for NO3- using methods found in the
HACH spectrophotometer manual. Four out of five wells had mean
nitrate concentrations less than the maximum containment level (MCL)
for drinking water (10 mg/L nitrate-N). Down gradient wells
showed a slight increase in nitrate concentration but still under the
MCL for drinking water. The well placed furthest away up gradient
from the composting windrows showed a mean concentration of 29.9 mg/L
NO3- -N three times higher than the MCL for drinking water. The
wells in close proximity to the compost were shown not to be
contributing excess nitrate to the
groundwater.
Kylie Krauss
May 7, 2007
Homovanillic Acid
as an Indicator of Neuronal Dopamine Levels In Mountain Bikers and
Non-Mountain Bikers
Mentor: Dr. Victoria Collins
Abstract: Gravity specific
mountain biking includes the high-risk events of downhill and
dual-slalom, where crashes are high-speed, severe, and frequent.
Psychologists have defined a personality trait of Thrill and Adventure
Seeking to describe a person’s willingness and desire to take risks and
participate in high-risk sports. The neurotransmitter dopamine
has been shown to be linked to the tendency towards risky
behavior. In certain people, the experience of risk may produce
an intense, pleasurable response, due to high levels of dopamine
release. Dopamine can be measured peripherally by measuring its
main metabolite, homovanillic acid, in easily accessible body
fluids. This study looked at measured homovanillic acid levels in
urine as an indicator of dopamine levels in competitive,
gravity-specific mountain bikers and non-mountain bikers. The
study population consisted of two groups of eighteen white,
college-aged (18-25 years old) males: bikers and non-bikers. With
informed consent, urine samples were collected from each group, with
sample collection beginning at the NCCA Collegiate National
Championships in October, 2006. The urine was analyzed for
homovanillic acid (HVA) using a Shimadzu LC-10ATvp reversed-phase High
Performance Liquid Chromatograph (HPLC) with electrochemical
detection. Hydration levels of each sample were accounted for by
measuring the creatinine concentration using the Jaffe Reaction of
alkaline picrate and taking the absorbance. Data for each sample
was recorded as a ratio of HVA to creatinine, and the mean ratios were
compared using a two-sided t-test with a Welch correction. There was a
significant difference (p=0.0428) between the HVA:creatinine levels in
mountain bikers and in non-mountain bikers, with mountain bikers having
a higher mean ratio. While this study is merely correlational and
limitations exist based on the peripheral nature of
psychopharmacological studies and neurotransmitter measurements in
humans, it does support trends shown in previous studies, suggesting a
direct relationship between dopamine levels and activity and
risk-taking behavior.
Tina Milne
May 14, 2007
Arsenic and
Cadmium Biosorption by the fungus Cunninghamella echinulata
Mentors: Dr. Mark Brenner and Dr. John Brock
Abstract: As arsenic and
cadmium continue to be released into the biota, presenting a variety of
problems, the need for development of waste treatment technology
increases. Mycoremediation, an organic, in-situ method of metal
remediation involving degradation or sequestration of metal ions by
fungi, is garnering attention. The metal ions are sequestered via
biosorption, a reversible, metabolism-independent metal uptake
mechanism that involves interaction of metal ions with metal binding
biomolecules located on cell walls. The objective of this study is to
establish whether the biomass of the filamentous fungi C. echinulata (var. elegans) is
capable of biosorbtion of cadmium or arsenic ions from a solution, and
if so, how biosorption efficiency is affected by initial concentration.
A culture was obtained, subcultured, and the fungal pellets were
harvested, dried to a constant weight, and pulverized. Metal solutions
were prepared and analyzed for their initial concentrations using an
ICP-OES, after which the fungal biomass was allowed to interact with
the solutions. The biomass was filtered out and the final metal
concentrations were analyzed. The greatest average arsenic uptake (277
µg/g) occurred in the 75 ppb As treatment. The largest
average percent reduction in arsenic concentration was 22%, observed in
the 25 ppb As treatment. The greatest average cadmium uptake, 13.3
µg/g, occurred in the 25 ppb Cd treatment. The largest
average percent reduction in cadmium concentration (22%) was observed
in the 25 ppb Cd treatment. Thus, this fungus is a candidate for
mycoremediation applications; however, further research of metal uptake
mechanisms and influencing factors is necessary.