Volume 8 Issue 4 March 2010

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https://doi.org/10.33697/ajur.2010.001

Editorial: The Continuing Surprise: Recent Scientific Advances

https://doi.org/10.33697/ajur.2010.002

Author(s):

C. C. Chancey

Affiliation:

American Journal of Undergraduate Research, University of Northern Iowa, Cedar Falls, Iowa 50614-0150 USA


Traits for predator selection on Pentaclethra macroloba seeds

https://doi.org/10.33697/ajur.2010.003

Author(s):

Gabriela Anhalzer, Michelle Fournier, Tim O’Connor, Louise Stevenson, and Mariel Yglesias

Affiliation:

La Selva Biological Station, Organization for Tropical Studies, Horquetas, Costa Rica

ABSTRACT:

Pentaclethra macroloba (Fabaceae: Mimosoidea) is a dominant species of canopy tree in Costa Rica’s Caribbean lowlands, constituting up to 40% of the local tree population in some areas. It has been suggested that P. macroloba’s dominance is due in part to low post-dispersal seed depredation, as few terrestrial seed predators can tolerate the high concentration of toxic alkaloids and free amino acids. Seeds are not immune from depredation, however. Several species of parrots and squirrels have been observed depredating pre-dehiscent legumes and may present selective pressure on P. macroloba recruitment. In this study, we assessed depredation patterns in P. macroloba to (1) determine if predators use legume and seed traits to select food items, (2) determine if such patterns represent an optimal foraging strategy for vertebrate predators, and (3) explore potential consequences of depredation on P. macroloba. Seed depredation was not correlated with legume valve side, legume size, seed number, or seed compartment size, though seeds at the distal end of legumes were more often extracted. Depredation patterns do not indicate that seed predators are foraging optimally and may be quickly satiated due to their low toxicity tolerance the abundance of seeds. Despite a lack of predator selection of various legume and seed characteristics, legume damage caused by depredation may interfere with the explosive dehiscence of P. macroloba and constitute a significant recruitment barrier.


KBO Astrometry Using Small Telescopes

https://doi.org/10.33697/ajur.2010.004

Author(s):

Rachel Bowens-Rubin, Katheryn Decker French, Dora Gao, and Christina A Jaworsky

Affiliation:

Department of Earth, Atmospheric, and Planetary Science, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, Massachusetts 02139 USA

ABSTRACT:

CCD images of Makemake (2005 FY9), the second largest Kuiper Belt Object (KBO), were taken with a 14-inch telescope during the summer of 2008. The position of Makemake was found by comparing its position on the frames to UCAC2 stars in the frame. Observations were limited by the tracking capabilities of the telescopes and atmospheric limitations. The average right ascension offset from the ephemeris was found to be 0.0134 0.3394 arcseconds, and the average declination offset was found to be -0.3855 0.4634 arcseconds. It is possible to do KBO astrometry with small telescopes, however several hundred frames are required to equal the quality of observations on larger telescopes.


Music-elicited EEG Activity and Emotional Responses are Altered in Schizophrenia

https://doi.org/10.33697/ajur.2010.005

Author(s):

Rondell Burge and Aimee Siebert

Affiliation:

Bethel College, 300 East 27th Street, North Newton, KS 67117 USA

ABSTRACT:

Studies of patients with schizophrenia using facial affect recognition and voice discrimination tasks have identified emotional dysfunction as a prominent clinical feature. In the present study we examine whether emotion processing in patients is also impaired in a less explicitly social context — continuous self-report of emotions during music using a two-dimensional (pleasantness X activation) emotion space. Electroencephalographic (EEG) activity was also recorded during this task since previous studies using EEG measures have found underlying cortical processes related to emotion. Twelve patients with schizophrenia and eleven controls listened to five 25-second songs. These songs included J.S. Bach‟s Invention #13 in A minor (BWV 784) (designated the original piece), and four computer-generated pieces of which two were designed to be similar to the original, and two were designed to be different. While no significant effects were found in the activation dimension of the self-report measures, the pattern of pleasantness ratings was significantly less differentiated among songs in the patient group than in controls. EEG asymmetry indices at frontal and central electrodes provided evidence of greater hemispheric activation asymmetry (with higher activation on the left) in controls than in patients, a difference that was significant at the central electrodes (C3 and C4). These findings indicate that individuals with schizophrenia interpret emotion-eliciting music differently than do controls, even in a relatively non-social setting, possibly because of less differentiated hemispheric representations.