Summer Science Research Abstract

Biology Summer Students 2006

Effects of Artificial Blood on Swimming in Leeches

Klaudia Gorska and Rebecca Donatelli

Mentor: Professor Peter Brodfuehrer

The presence of food in an animal’s environment may elicit a nervous system response that affects other behaviors not directly involved in feeding. Previous research in the Brodfeuhrer lab has shown that when the medicinal leech, Hirudo Medicinalis, forages for blood (i.e. a sausage bag containing a solution of artificial blood), the likelihood of eliciting swimming or crawling by stimulation of the skin increases.  In addition, it was shown that stimulation following application of artificial blood to the anterior end (mouth and head) of an optherwise isolated nervous system less frequently initiates swimming when compared with stimulation when the anterior end is in pond water.  The presence of blood also decreases the duration of individual swim bouts. 

The goal of this study is to further our understanding of how sensory input modifys swimming behavior by investigating the effects that artificial blood have on neurons involved in generating swimming.  Using isolated anterior end-isolated nervous system preparation, we will record intracellularly from neurons known to be involved in generating swimming while applying artificial blood to the anterior end.  Changes in neuronal activity will then be correlated with changes in the ability to initiate swimming.

Polychaete Morphological Assay

Elizabeth Diamond

Mentor: Dr. Stephen Gardiner 

The polychaetes,or bristled worms, comprise an enormous number of unique marine worm species, each displaying a variety of forms and specialized structures. The object of our research is to collect live specimens of polychaete worms from the Delaware coast and take them back to the lab to perform a full range of morphological assays using transmission electron microscopy (TEM).  We are particularly interested in one widely-spread genus of marine worm, Magelona.  Magelona can be somewhat fragile and are relatively difficult to collect, but should we find any specimens of this type, we would focus on examining the morphology of the creature’s unique feeding palps.  Unlike other species with the more common grooved palps, Magelona’s long palps are studded with sticky projections to capture small prey.  Using the TEM, we hope to provide a clearer picture of these, and a wide range of other unique structures from different polychaete species.  With the resulting micrographs, we hope to create a comparative analysis of structures such as palps, chaete, etc., across the types of specimens collected. Larval specimens, if collected, will be used to examine the growth and development of those species of polychaetes.  Proper techniques of specimen fixing, embedding, and sectioning will be observed for all laboratory work.

Differential Transport of Synaptic Proteins

Jaya Vasudevan

Mentor: Dr. Karen Greif

           Within the nervous system, nerve cells communicate through structures known as synapses, which function by releasing the contents of small vesicles containing neurotransmitters at their presynaptic terminals when the proper stimulus is applied. Developing nerve cells need to grow and extend into axons, the elongated process that contains the synapse, and at its end synthesize and transport synaptic proteins needed for function to the synaptic terminals. Several synaptic proteins have been identified that have defined their roles in synaptic function: synaptotagmin (syt), synaptobrevin (VAMP), SNAP-25, and syntaxin. These proteins are expressed in developing neurons several days before any synapses are formed. Previous research done in our laboratory suggests that the vesicular proteins, syt and VAMP, are transported earlier down the growing axon than pre-synaptic membrane proteins, SNAP-25 and syntaxin. These data suggest that different synaptic proteins may utilize different transport mechanisms, which cause them to be transported at different times down the axon. Our specific experiment therefore is to determine the time course of transport of the synaptic proteins in the developing sympathetic neurons in vitro. Double labeling of the cells using fluorescent antibody markers through a process called immunocytochemistry will be employed to compare the patterns of transport in different synaptic proteins, specifically synaptotagmin, syntaxin, VAMP, and SNAP-25. Image analysis will then be conducted using confocal microscopy to analyze these fluorescent-labeled antibody proteins to note the distribution and patterning of the synaptic proteins. Why certain proteins are apparently transported earlier than others and what roles these proteins play in early neuron development will be studied in other experiments using the data collected from this research.

Supported by NIH AREA grant #1R15NS4303.

Rasgrf1 gene in mice

Rachel Horton

Mentor: Professor Tamara Davis

Genomic imprinting is a mammalian-specific phenomenon that affects the expression of a subset of genes.  Most genes are expressed from both the maternal and paternal alleles.  Imprinted genes, however, have monoallelic expression dependant on parental origin.  For some genes, the maternal allele is expressed while the paternal allele is silenced; the reverse is true for other imprinted genes.  Approximately 80 imprinted genes have been identified in mice, most of which have homologous sequences and imprinting similarities in humans.  
 
Imprinting refers to a molecular mark that distinguishes the parental origin of each allele of an imprinted gene.  A common mechanism for marking one of the two alleles is through the addition of methyl groups (CH3) on cytosines that are adjacent to guanines in the nucleotide sequence.  Although the mechanisms are not entirely understood, allele-specific DNA methylation and chromatin structure are thought to play a role in whether an allele is silenced or expressed.  The differential expression observed in imprinted genes has implications for normal growth and development in humans as well as assisted reproductive technology, epigenetic regulation and evolutionary strategies.
 
The Rasgrf1 gene (RAS protein-specific guanine nucleotide-releasing factor 1) is an imprinted gene that plays a role in regulating postnatal growth by controlling the synthesis and release of a growth hormone.  In one study, researchers found that mice with a mutant Rasgrf1 gene weighed 15% less than their wild-type littermates as adults.  Scientists have suggested that the biochemical explanation for this is that Rasgrf1 is involved with controlling the release of insulin from β cells.  Expression of Rasgrf1 has also been found in neurons in the brain and has implications for long-term memory and learning.
 
My research will focus on the Rasgrf1 gene in mice.  Methyl groups that are added to certain portions of the DNA mark the paternal allele of Rasgrf1, which is expressed from only the paternally-inherited allele in many tissues.  I will examine the methylation of this gene on the maternal and paternal alleles at different stages of embryonic and extra-embryonic development.  The purpose of this study is to expand our understanding of the differential methylation in embryonic tissues and initiate novel research into the methylation patterns in extra-embryonic tissues.  Placental development plays a critical role in the growth of the embryo and nothing is known about Rasgrf1 expression in this tissue.  In addition, I will run an expression assay to understand where Rasgrf1 is being transcribed into mRNA in select embryonic and extra-embryonic tissues to examine imprinting status.  This will help to determine the relationship between differential methylation and the actual expression of Rasgrf1.

Yaena Park

Mentor: Professor Tamara Davis

The forms and functions of organisms are dependent on the regulation of gene expression. This is attained by regulating gene activity at specific developmental stages or in specific tissues. In order for proper growth and development to take place, it is important that developmentally important genes can either stay in inactive or active states which are inherited in the soma. For other developmentally important genes, the level of expression must be regulated. Genomic imprinting is one mechanism in which expression levels are controlled. Although most genes are expressed from both copies, imprinted genes are only expressed from one of the two paternal alleles. In order to achieve this parent of origin-specific expression, the two alleles (copies) must be marked.

Studies have shown that the epigenetic control of gene expression in mammals is achieved by DNA methylation. Here, epigenetic can be defined as the changes in gene expression without change in nucleotide sequence. DNA methylation is the addition of methyl groups at cytosine residues in CpG dinucleotides in the DNA. Many imprinted genes studied in the past have differentially methylated regions (DMRs) where one allele is methylated and the other is unmethylated. This modification can serve to mark parental origin of each allele and many also play a role in regulating gene expression.

Our research focuses on one of the imprinted genes in mice, Rasgrf1. Rasgrf1 is a guanine nucleotide exchange factor gene. It is known as playing a role in long-term memory formation and growth control. In Rasgrf1, the expression pattern varies in different tissues. It is expressed solely from paternal allele in the brain; other tissues may have no expression, or have expression from both parental alleles. It is also found that Rasgrf1 is methylated on the paternal, expressed allele. A differentially methylated region is proposed to control imprinted expression. But, we have shown that differential methylation is present in all tissues, regardless of expression state. Therefore, there isn’t a direct correlation between methylation and expression of particular allele.

Our lab is interested in studying the tissue-specific regulation of gene expression of Ras gene and the relationship between DNA methylation and imprinted expression. We want to determine its role in expression. We are currently examining the methylation status of a potentially methylated region near the Ras promoter site in order to identify any other DMRs around Ras gene. If differential methylation correlates with different expression, this region may play a role in regulating expression of Rasgrf1. If this region lacks differential methylation, then there is no corresponding relationship between differential methylation and imprinted expression.

            In recent decades the Philadelphia area has experienced rapid and extensive developmental growth, and development continues to expand into surrounding green areas.  In the last ten years alone, what used to be the outer suburbs, interspersed with wooded areas and ringed by agriculture, has seen the quick construction of large housing developments, retail outlets, and the widening of roads to increase traffic capacity. This rapid land conversion could have many ecological consequences, including a negative effect on bumblebee (Bombus spp.) populations.  It is the goal of this study to evaluate species composition in different landscape matrices in order to determine the effect development intensity in the surrounding landscape may have on species richness and the presence of particular bumble bee species.  The study will take place from the beginning of June to the middle of August 2006 in Philadelphia, Montgomery, Chester, Delaware and Bucks counties in Pennsylvania.  Fifteen replicate sites containing meadow and woodland periphery will be chosen from urban, suburban and rural areas within these counties.  Each site will be sampled via net collection tri-weekly between June 1 and August 31 (4 total samples) to account for early- and late-emerging species of Bombus and early- and late-blooming species of flowering plants. After collection, the specimens caught will be frozen, pinned, and identified to species. As floral diversity may be a factor in species composition at a given location, I will also conduct a flowering vegetation survey at each site.  The extent and intensity of development surrounding these sites will be quantified using landuse data made available by the Delaware Valley Planning Commission in the Geographical Information Systems (GIS) program ArcView 9.1.  The results of this spatial anaylsis will then be compared to the species composition found at each site and landscape type as a whole (urban, suburban or rural).

References:
Williams, Paul. 2005. Does specialization explain rarity and decline among British bumblebees? A response to Goulson et al. Biological Conservation 122, 33-43.

Squires, ed., Gregory D. Urban Sprawl: Causes, Consequences and Policy Responses. Urban Institute Press: 2005.

Sara Chan

Mentor: Professor Karen Greif

A synapse is the structure through which neurons communicate by the release of neurotransmitters. The presynaptic terminal is at the end of cell extensions known as axons that transmit electrical signals in the neuron system.  In addition, the presynaptic terminal has an assortment of proteins synthesized in the cell body and are transported down the axons to aid in the fusion of the vesicles with the cell membrane to release their contents.  Before communication can occur, a developing neuron must extend an axon, synthesize synaptic proteins, and transport them to synaptic terminals. Many proteins that play a role in synaptic function have been identified. Evidence suggests that some synaptic proteins may contribute to neurite outgrowth as well.

One of the essential proteins involved in the these processes is synaptotagmin(syt).  Syt is the calcium sensor in which triggers the membrane fusion event.  In a previous study, it was observed that an increased production of syt in neurons correlated with increased axon branching.  It has also been noted that syt is present at the earliest stages of axon development.  These observations suggest that syt may be a contributing factor in developing axon outgrowth and branching.  We study axon branching using neurons from the superior cervical ganglion (SCG) of neonatal rats. These neurons will be infected in vitro using a virus to cause an overproduction of syt that is fused to YFP.  YFP is a fluorescent tag that will act as a surrogate visual marker for the presence of syt.   To control for non-specific viral effects, YFP alone will be introduced via the same method.  The parallel experiments are expected to reveal increased axon branching in the syt-YFP infected cells relative to the cells infected with YFP alone.  The results of the experiment will be observed using confocal microscopy and live cell imaging.

Supported by NIH AREA grant #1R15NS40303.

Summer Science Research Abstract

Chemistry Summer Students 2006

Synthesis and Investigation of Molybdenum Pterinyl-dithiolene

Rebecca Petit

Mentors: Prof. Sharon Burgmayer

The molybdopterin family of enzymes plays a vital role in many metabolic reactions involving redox reactions of sulfur and nitrogen centers in diverse substrates, including nitrogen assimilation in plants[1] and the anaerobic respiration of many bacteria[2].  In humans, deficiency in molybdopterin enzymes like sulfite oxidase causes fatal neurological  damage[3].   Despite the biological importance of these enzymes, much about their structure and activity remains unknown.  Their most unusual feature, a pterin-substituted dithiolene chelating the central metal ion, was conclusively determined within the past decade[4], and it is suspected that pterin redox reactions play an important role in molybdoenzyme function.

This summer in the Burgmayer lab, I will be working together with Amy Rothkopf to synthesize molybdenum pterinyl-dithiolene complexes analogous to the molybdopterin portion of the molybdenum cofactor from the metal sulfido tetrasulfide precursor Tp*MoIV(S)(S4)-and three different pivalated pterinyl alkynes, designated AEPa, IPEPP and DIFPEPP (synthesized by Candi Greeman).  In addition to exploring the effects of the various substituents on the redox chemistry of the pterinyl portions of the complexes using a variety of spectroscopic techniques, I will be working towards refining the efficiencies of these reactions, increasing their yields and purities.

[1] R. R. Mendel, Planta, 203, 399 (1997).

[2] R. W. Jones, A. Lamont, and P. B. Garland, Biochem. J., 190, 79 (1980).

[3] C. Mize, J. L. Johnson, and K. V. Rajagopalan, J. Inherited Metab. Dis., 18, 283 (1995).
[4] A. Jankielwicz, O. Klimmek, and A. Kroger, Biochim. Biophys. Acta, 1231, 1231, 157 (1995).

Synthesis and Study of Models of the Molybdenum Cofactor

Candacia Greeman

Mentor: Professor Sharon Burgmayer
 

Figure 1: Structure of MoCo

Molybdenum (Mo) is a metallic trace element that is important for the proper functioning of most living organisms. A lack of molybdenum enzymes in humans can lead to several health problems. Molybdopterin, a dithiolene organic complex, couples with molybdenum to form the Molybdenum Cofactor (MoCo). Analyses of the formation of molybdopterin through the synthesis of models, improves the possibility of understanding how the cofactor works.

The Burgmayer Lab’s approach to the syntheses of  MoCo models consists of two stages. The first stage constitutes the formation of one of the pterins; acetyl, phenyl, and difluoropheynyl, ethynyl pivulated pterins, fondly referred to as AEP, PEPP, and diFPEPP, respectively, using 2-pivaloyl-6-chloropterin (11). The pterin is then reacted with Mo to generate one of three models of MoCo. The oxidation states and other properties of Mo in these models can then be studied.

During my summer research, I will begin the synthesis of molybdopterin by completing the first seven steps of an eight-step process repeatedly, so as to stockpile (11) for conversion into AEP, PEPP or diFPEPP. I will also synthesize these pterins which will be used by my research colleagues, Rebecca Petit and Amy Rothkopf to synthesize the MoCo models.

Figure 2: Reaction 6: Pivalation

Molybdopterin Chemistry

Amy Rothkopf

Mentor: Professor Sharon Burgmeyer

A common motif of biochemistry is the role metals play as cofactors in the active sites of enzymes. Molybdenum enzymes are found throughout biology, and fulfill important tasks such as nitrogen metabolism in plants. All molybdenum enzymes employ this metal in the same way in the form of Moco, the molybdenum cofactor. The most important piece of this complicated cofactor is a single molybdenum atom with two important components, or ligands. This unique constituent is incorporated into every molybdenum enzyme, and is known as the molybdopterin ligand.

This special piece of the molybdenum cofactor controls its reactivity, and begins to explain the bioinorganic chemistry of Mo enzymes. For this reason, the study of the electronics, spectroscopy, and mechanisms of this molecule is a topic of great interest in our research.

This summer, I will be performing reactions to synthesize molybdenum compounds that are substituted with this crucial ligand to further my understanding of their oxidation-reduction chemistry. Generally, this reaction has the following setup:
                            

                                                
      
Pterinyl Alkyne                        +             Tp*Mo(O)(S4)         →     Tp*Mo(O)(S2Alkyne)

                                                                    Metal Sulfide        
Rebecca Petit and I will be studying variants of this reaction and the synthesis and analytical techniques required for their success. Throughout the summer we hope to achieve a better understanding of molybdopterin chemistry by investigating the effects of varying substituent groups (labeled R in the above figure) on this portion of the molybdenum cofactor.

Ligands and Transition metals: A Complex Relationship

Eden McQueen

Mentor: Professor Goldsmith

         The relatively recent discovery of carbon nano tubing, microscale tubes consisting of rings of carbon atoms, opens up new opportunities for research as to the potential uses of these tiny little conductors.  One way of creating new uses for the nano tubing is by using transition metal complexes to “funtionalize” them, in other words, make it so they can respond to a chemical stimulus in a specific manner.  The research done here involves synthesizing various organic ligands and reacting these compounds with transition metals, such as cobalt, to produce a complex.  The resulting complex has a central metal ion that has little aromatic “appendages” which can adhere by non-covalent bonding to the carbon surface.  The idea is that these ligands can “tag” the nano tubing so that it performs in the desired way, and the more soundly they adhere, the better.  The research of this lab focuses mainly on creating many different variations of these complexes to see which are the most effectual in achieving this goal.

Carrie Womack and Alessandra Samero

Mentor: Professor Frank Mallory

[n]Phenacenes are compounds consisting of a particular number (n) of benzene rings fused together as shown in the following example:

[6]phenacene; n=6

These compounds are potentially useful for electrical conductivity due to their conjugation.  When n is sufficiently large, electron movement may be promoted via the large pi-systems.   This assumption is based on the fact that [n]phenacenes are very similar in structure to the highly conductive graphite, a small section of which is pictured below.

[11]Phenacenes have been previously synthesized in the Mallory Lab, with tertiary butyl side chains attached to provide solubility.  Because the resulting solubility was only barely adequate, the synthesis of phenacenes is currently being attempted with the more powerful solubilizing polyether side chains attached.

     The goal for this project is to synthesize the [7]phenacene and the [15]phenacene, pictured below.  The planned synthesis of these molecules involves a multi-step process using Horner-Emmons reactions, benzylic brominations, photocyclizations, and Arbuzov reactions.

[7] phenacene

Rachel Usala

Mentor: Professor Jonas Goldsmith
 

In a technological society where smaller is better (think about the new nano-ipod), there has been increasing interest in nano-circuits, that is electronics at the molecular level. The focus of this research is to study transition metal complexes and their building block, ligands, because of their potential nanotechnology application.

Transition metals, such as iridium, ruthenium, rhodium, and cobalt, have the ability to complex with organic ligands. The focus of this research is to synthesis a library of transition metal complexes and characterize their electrochemical and physical properties. Two such complexes are diagramed below, where M represents a transition metal complex and one ligand is highlighted in red.

These complexes and related compounds have the potential to functionalize with carbon surfaces via extensive non-covalent interactions with the aromatic ligands. Functionalizing with carbon surfaces introduces the potential for these complexes to be useful in creating nano-circuits. Theoretically, the more extensive the aromaticity of the ligand pi system, the more it should interact with the carbon surface. Electrochemical techniques such as cyclic voltammetry will be used to study the adsorption kinetics and efficiency of each complex.

Summer Science Research Abstract

Computer Science

Summer Students 2006

Julia Ferraioli, Leslie McTavish and George Dahl

Mentor: Professor Doug Blank

Developmental robotics involves designing learning systems for robots such that they are capable of displaying sophisticated behaviors that have not been directly programmed into them. Traditionally, robots can only do what we program them to do. They are not capable of acquiring any new information and therefore are not able to adapt to new situations. Because of the limitations of this traditional approach, new methods are being explored.

The developmental approach to learning attempts to create a models that mimic human learning development. The robot should first develop a sense of its self and its environment by detecting and establishing a relationship between its sensor and motor values. We will try to do this by experimenting with combinations of various established learning algorithms.

Learning algorithms are methods by which the system autonomously makes generalizations about input which is provided to it. These algorithms allow the system to learn a task or task without explicit programming or memorization. To achieve our goal we will design developmental algorithms which incorporate several learning processes such as neural networks, self-organizing maps (SOMs), resource allocating vector quantizers (RAVQs), growing neural gas (GNG) as well as others.

In the next stage of development, the robots will be assisted by social interactions with other robots or human guidance. We believe social interaction is an important aspect of human learning and may also prove to be useful in developing intelligent robots. Our experiments will test the effect of social interaction in the developmental process. We hope to design a developmental learning system that can be applied to both simulated and real robots and is independent of environment and robot type.

Summer Science Research Abstract

Geology Summer Students 2006

One of the long standing debates in geology is how mountain belts (e.g., Appalachians, Alps) become curved in their map view.  My summer research project is focused on understanding, quantifying and classifying the actual rotations involved in curvature formation in two belts – the Wyoming Salient (a “salient” is a geometric term meaning that there is a curvature towards the foreland) in the western U.S. and the Cantbrian Mountains in northern Spain.  Ultimately this work will lead to a better understanding of the evolution of curved mountain belts in general.  Paleomagnetism, the study of the earth’s ancient magnetic field as recorded in the rock record, will be used to quantify the rotations, document fold and deformation evolution, and construct an internally consistent deformation history for the two belts.

It should be noted that just because a mountain belt is curved, does not necessarily require that the belt experienced significant rotation during its formation.  In fact many belts have a primary curvature related to the ancient geometry of the landscape prior to mountain belt evolution.  Consequently, the first step in understanding the evolution of a belt is classifying the relationship between a belts curvature and its total experienced rotation.  The term orocline refers to a mountain belt configuration where first a linear mountain belt is created through convergence, and then it is bent into a horseshoe shape—like bending a long eraser between your thumb and index finger.  A primary arc describes when curvature is acquired during an initial deformation event without significant secondary rotation.  Lastly, a progressive arc acquires its curvature progressively throughout the belt’s deformation history. 

The two mountain belts that we are researching and classifying this summer are the Wyoming Salient and the Cantabrian Arc.  The Wyoming Salient (a portion of the Rocky Mountains between Salt Lake City, Utah and Jackson, Wyoming) is argued to me created through a deformation gradient where deformation is greatest at the tips of the salient and less in the midsection, causing the entire salient to bend.  This gradient is an example of “work hardening”, where the pile-up of strain at the salient tips causes the geology to lock itself in place.  On the other hand, the Cantabrian Arc is related to the convergence between Gondwana (an ancient landmass that encompassed all of the southern hemisphere continents) and Laurussia (an ancient continent that comprised North America and northern Europe).  The curvature in the Cantabian Arc was acquired in two phases: 1) the early phase was an east-west shortening event that produced a north-south linear belt, and 2) a final phase in which north-south shortening caused arc tightening.

With increasing research and understanding, hopefully an accurate, three-dimensional kinematic model of mountain belt curvature can be created for both the Wyoming Salient and the Cantabiran Arc, and ultimately these models will enlighten our understanding of mountain belt curvature in general.

Glacier National Park, Montana
L. Camille Jones

Mentor: Professor Catherine Riihimaki

Glaciers fluctuate in response to decadal or centennial climate trends as opposed to shorter seasonal or annual climate anomalies creating environmental records in glacial ice and sediment reflect long term environmental trends.  Sediment records of organic and inorganic carbon can serve as a proxy for recent anthropogenic and Holocene environmental changes in the park.  In this study, carbon content of the Swiftcurrent Lake cores will be measured by coulometry.  Organic carbon content reflects bioproductivity in the lake and surrounding area while inorganic carbon in the lake sediment indicates presence of minerals like calcite or dolomite.  Two 5 meter lake cores were collected in Swiftcurrent Lake in 2005.  Swiftcurrent is the third lake in Swiftcurrent Valley that collects meltwater from Grinnell Glacier and is the most accessible to park visitors.  One Swiftcurrent core was sampled at every centimeter for coulometry.  The core samples are estimated to be 3% carbon which is likely a mix of limestone sediment and organic material.  The sedimentation rate is approximately 52mm/year and the core represents approximately 10,000 years.   Park visitors’ presence at the Lake may be detectable in the first five centimeters of the core because or increased human activity since the 1915 completion of a hotel on the shore of Swiftcurrent Lake.

Summer Science Research Abstract

Math Summer Students 2006

Summer Science Research Abstract

Physics Summer Students 2006

A pulsar is a rapidly rotating and highly magnetized neutron star that emits pulses of radiation at regular intervals. Our project is based on the collaboration with the Radio Observatory of Arecibo, Puerto Rico and it involves collecting and analyzing data on the radiation that the pulsars emit at radio frequencies. The first step is collecting the data using the observatory. This can be done either remotely either by going there. Although most of the data are taken remotely, the project involves a trip to the observatory, with the purpose of seeing and understanding how it functions. The next stage of the project is using computer programming to develop algorithms for an efficient processing of the data. We use these algorithms to process the data and to create a model of each pulsar, model that contains information about the pulsar’s position in space, rotational period, dispersion measure, and slowdown rate. The ultimate goal of our summer research is to create a database of the times that the pulses arrive at the observatory, over a period of several months. This would allow us to compare the expected arrival times of the pulses with the observed ones and adjust the predicted model of the pulsar in order to be in concordance with the empirical data. As a result, we would be able to create a more precise model of the pulsars coordinates in space, dispersion measure, rotational frequency and change of rotational frequency over time. This more accurate set of data is ultimately used for analyzing the intrinsic properties of the pulsar, such as the strength of its magnetic field or whether the pulsar forms a binary system with a companion star.

Summer Science Research Abstract

Psychology

Summer Students 2006

Mindfulness and Anxiety

Margaret Miller

Mentor: Professor Mark Schulz

Mindfulness can be defined as the ability to focus one’s attention on present moment experiences in a nonjudgmental way (Kabat-Zinn, 1994). Some conceptualizations of anxiety suggest that anxious people focus too much on internal signs of physiological awareness. However, they often overestimate signs of physiological arousal and their awareness may not be accurate which would mean that they have low mindfulness (Hofmann, 1999). I will be examining links between anxiety and bodily awareness (often thought of as a sign of mindfulness), as measured by the accuracy of self-reported thought
count and self-reported muscular tension in the forehead. I will also be comparing the self reports of mindfulness and anxiety to our physiological data. Anxious people may have low mindfulness because they are unable to stay in the moment because they spend much of their time worrying about the past or the future (Molina, Borkovec, Peasley, & Pearson, 1998). By examining the accuracy of thought cunting and forehead tension, the difference between the hypersensitivity of anxiety and mindfulness may emerge.

It is hypothesized that anxious people will be more accurate, and thus more mindful, in their ability to correctly recall the number of their thoughts, but less accurate, and less mindful, in their ability to correctly estimate their forehead tension. In addition to examining these two categories of mindfulness, I will also be researching how mindfulness fits in with cognitive behavioral therapy for anxious people, how people can be taught to be more mindful, and the benefits of being mindful.

Actions of the Amygdala

Dana Bakalar

Mentor: Professor Thomas

The amygdala is a section of the temporal lobe which acts to create anxiety. It is believed that several other areas, such as the medial prefrontal cortex and the lateral septum, send inhibitory inputs to the amygdala to mediate these anxiety producing effects. In order for the amygdala to cause anxiety, then this inhibitory system must be inhibited in some way so that the first sign of increased amygdala firing is not countered by these inhibitory regions. The mechanism of inhibition is still unknown, but to understand it we must first understand the relationship between the amygdala and its inhibitory regions.

This study will examine the actions of the amygdala and the lateral septum in conditioned fear environments. Rats were implanted with a bundle of eight small electrodes in each of these regions so that single cell activity could be recorded. Rats were then placed alternately in a chamber where they were safe from shock and one in which they received regular shocks. The two chambers were designed to look very different from one another so that rats could tell them apart easily. We hypothesize that in the safe chamber the lateral septum will fire more than the amygdala, since it is acting to inhibit the fear causing firing there and that in the shock chamber the amygdala will show more activity and the lateral septum less.

We will then administer an anti-anxiety drug, chlordiazopoxide, to the rats and put them back into the chambers. We predict that with the addition of the drug, the differences in firing rate in each chamber will be evened out, since the drug blocks the inhibition of the lateral septum that is the cause of increased amygdal firing.

Use of Observer and Character Viewpoints in Storytelling

Kara Rosania

Mentor: Professor Robert Wozniak

It is unclear whether the concepts a person uses while telling a story are related to the perspective that the speaker has of that story. The purpose of this study is to examine this issue. Speakers represent stories from one of two viewpoints: character or observer viewpoint. A character viewpoint one in which the action is described as though the speaker is performing it himself, as though he were the character in the story. An observer viewpoint is one in which the person represents the character, object being acted upon, and/or action as though he were observing the action from an external perspective.

This study seeks to answer the question of whether a story is more frequently represented from a character viewpoint when telling a story that was read as a first-person narrative than when telling a story read as a third-person narrative, and if a story is more frequently represented from an observer viewpoint when telling a story read as a third -person narrative than when telling a story read as a first -person narrative. Participants are given a story to read and then retell from memory. All participants are shown a story with the same plot, but half are shown a version told in the first-person perspective and half are shown a version told in the third-person perspective. During the retelling, the concepts used by participants are recorded as either Character Viewpoint or Observer Viewpoint.

We hypothesize that those participants who read the story written in the first-person will feel that they are viewing the events from the perspective of the character telling the narrative, and those who read the story written in the third-person will feel like they are viewing the events from the perspective of an observer. These perspectives will match the types of concepts used in the retelling.

Comprehension of Verb Oriented Gestures

Emily Lehrer

Mentor: Professor Robert Wozniak

            Children learn to represent objects in a variety of ways. In the earliest stages of life, infants can only process objects that they are directly acting upon. Rapidly, the infant becomes able to think about these objects when they are not directly being acted upon or even in sight. In the toddler years, they are able to think about and represent these objects that are not immediately present through gestures.

These gestures can take two forms: body part as the object (BPO) gestures and imagined object (IO) gestures. It is important to note, however, that these gestures do not represent static objects, but rather actions one would perform with the object in hand. Obviously, there are many questions that arise around these toddlers’ gestures: Does it matter for comprehension whether the gesture is BPO or IO? Is there an age where one of these gesture types is more common? Would the child recognize the gesture and relate it to a “real world” action?

            To test this, I have arranged a two-phase gesture task to administer to this age group. The child would be asked to view video prompts where two empty-handed gestures are being preformed. The child will be asked to indicate which side of the screen has the person performing the target action (e.g. hammering). There will be two conditions for this task; the child will either be assigned to viewing all BPO or IO gestures.

Next, to assure that the child is selecting (or not selecting) the correct gesture because they know (or do not know) the action, the second phase will show a person performing two tasks with an object in hand. On one side of the screen the object will be using the object for its intended purpose (e.g. a hammer for hammering). On the other side the person will be using the object incorrectly (e.g. a hammer for drinking). The child will once again be asked to indicate which side of the screen has the person performing the target action. There will be an equal number of trials in each phase so that all the object actions covered in the empty-handed phase

Sex Differences in General Knowledge

Liz Hong

Mentor: Anjali Thapar

Intelligence is a frequently researched topic in the field of psychology.  The predominant model of intelligence found in the literature describes intelligence as having two subcomponents: fluid intelligence (Gf) and crystallized intelligence (Gc).  Fluid intelligence is often described as reasoning ability—this form of intelligence is necessary for such tasks as solving algebraic equations and an individual's Gf deteriorates during later life.  Crystallized intelligence is involved in acquiring and maintaining a broad vocabulary and in ability to learn new foreign languages; unlike Gf, Gc remains mostly stable throughout an individual's adulthood.

Both fluid and crystallized intelligence are further divided into their own subcomponents.  Of particular interest to this research is a subcomponent of Gc known as general knowledge.  General knowledge is roughly defined as information that is disseminated to the public via multiple means of media (examples domain of general knowledge are: music, sports, general science concepts, history, etc.).  Although the overall construct of intelligence has been a research focus for many decades, general knowledge received minimal attention until recently.  In the past several years the research on general knowledge has indicated that, like other aspects of intelligence, sex differences exist within this subcomponent: males significantly and substantially outperform females on tests of general knowledge.  One study found that these differences were not accounted for by bias in the tests used to measure general knowledge (such that the questions might favor males) or by "differential experience" (due to different environments during childhood).  Yet, no possible cause for this phenomenon has been found or put forth.

Therefore, the current research seeks to replicate the findings of previous studies while utilizing a different test from that found in most of the literature.  Additionally, a major goal of the experiment will be to gain insight into what variables lead to this disparity in general knowledge between males and females.

Self Report in Pigeons

Abbey Mann

Mentor: Professor Newman

Previous research has been done that examines the accuracy of pigeon self-report. It is not clear, however, if the results of these experiments, which indicated that pigeon are accurate, actually measures self-report. It is possible that previous research was actually measuring the accuracy with which pigeons recognize what response is asked of them, not the accuracy with which they discriminate their own chosen behavior. This experiment attempts to tease apart these tasks in an effort to determine whether pigeons really can accurately report their own behavior. To obtain reinforcement (access to food), the pigeons were be required to respond to a differential reinforcement of low-rate of behavior (DRL) or a differential reinforcement of high-rate of
behavior (DRH) schedule. The longer and shorter intervals of time both started at 1 second and were gradually moved apart from one another. Eventually the DRH required a .5 second inter-response time and the DRL required a 6 second inter-response time. Hence, the DRH required the pigeon to peck fast and the DRL required the pigeon to peck slow in order to obtain reinforcement. What initially makes this experiment different from previous work is that after the probe phase (in which the pigeons are taught to discriminate between the DRL and DRH), they are presented with a choice of either schedule and then asked to report on their own behavior.