Neutrinos and antineutrinos are elementary particles with no electric charge and very small masses. From neutrino oscillation experiments we know their mass differences but not their absolute scale. Additionally, it is unknown whether neutrinos are their own antiparticles. These are two of several significant questions in neutrino physics and are important for furthering our fundamental understanding of the universe as we extend the Standard Model of particle physics. These questions can be probed by a search for the rare hypothetical radioactive decay known as neutrinoless double beta decay. The Majorana Demonstrator experiment will look for neutrinoless double beta decay in ⁷⁶Ge. Currently, the Majorana Demonstrator is in the development stage, and involves the collaboration of several universities and national laboratories. My research characterizes electrical crosstalk between nearby readout channels for this experiment. As neutrinoless double beta decay is hypothesized to such a rare process, a thorough understanding of the electrical crosstalk is necessary to adequately interpret the measured signals.

Neural networks are often employed to model the brain. One such model developed by Numenta’s research group is the hierarchical temporal memory (HTM) model. A comparison of the HTM model and more conventional neural networks such as the network architectures available in the Stuttgart Neural Network Simulator (SNNS) is missing from the literature. This study aims to report on the performance on machine learning problems of HTM neural networks as compared to the performance of other common network architectures. The HTM neural network will either be built on the JAVA platform using the descriptions in Numenta’s publications or be used as provided by Numenta for public use. The SNNS network architectures will be used as provided by the University of Stuttgart. Possible learning problems considered will include: motion detection, character recognition, recognition and tracking of humanoid forms, object identification, and general pattern recognition. Possible SNNS network architectures include: backpropagation through time (for recurrent networks), quickprop through time (for recurrent networks), self-organizing maps (Kohonen maps), TDNN (time-delay networks) with backpropagation, Elman networks and extended hierarchical Elman networks. Evaluation of a network’s performance on each problem will be based on accuracy of identification, and time required for computation, while holding learning resources constant (same time exposure and same number of examples during learning stage). A qualitative comparison of the similarities of the learning problems to cortical learning algorithms and brain architectures may be attempted depending on time constraints. These results will be useful for evaluating both the usefulness of HTM neural networks and their connection to the cortical learning algorithm.

When massive stars reach the end of their lives, they erupt in enormous explosions known as supernovae, leaving behind clouds of shocked gas and dust known as supernova remnants (SNR). The primary technique to measure the mass of the progenitor star requires waiting for the star to explode and examining pre-explosion Hubble Space Telescope archival images of the site, which may or may not exist. This technique is constrained by rarity of supernovae, and as such only ~25 progenitors have any mass constraint whatsoever in the literature. We employ an alternative technique in which we examine color-magnitude diagrams of the regions surrounding known supernovae to measure their star formation history. We then use this star formation history to assign an age to the progenitor star.  By employing stellar evolution models, we convert this age to a mass. Because we do not rely on identification of the specific progenitor star in the images, we are free to apply our technique to cataloged SNR, drastically increasing the number of available targets. We apply our method to ~135 cataloged remnants in the nearby spiral galaxies M31 and M33, representing a dramatic increase in the number of currently known masses. We examine the distribution of these derived masses and comment on implications for supernova physics.

 Galaxy formation theories call for all galaxies to be embedded in massive extended dark matter halos. Ideally, we would use thousands to millions of tracer particles to map the dynamical environment around galaxies to constrain the properties of dark matter. Reality limits us to using only the dynamical tracers that are luminous enough to actually be observed. The spiral galaxy NGC 4258 has numerous small galaxies surrounding it that appear to be satellite galaxies, and can therefore be used as dynamical tracers. To determine if these smaller galaxies are indeed satellites, we examine their redshifts by combining spectroscopic observations from the APO 3.5-meter telescope with SDSS spectra. Of the 33 observed objects, 22 appear to be members of the system. Using the projected line-of-sight velocities of the satellite galaxies and a Jeans equation approximation, we estimate the mass of NGC 4258 out to a radius of 260kpc to be 6x10¹² solar masses with an error of 50%. When utilizing a more rigorous set of criteria to determine which candidate galaxies are actually satellites, we are left with only 8 true satellites and derive a new mass to be 1.3x10¹² solar masses out to a radius of 230kpc. Further observations are expected to yield around 20 to 40 more satellite velocity measurements, which will improve our mass estimate and significantly reduce our error. By searching the SDSS database, we believe we can find other galaxy systems that host enough satellites to repeat this technique.

Exoplanets are planets outside our solar system. As they do not emit light of their own, these objects have historically been much harder to find and study than stars. One detection method exploits the slight dimming of a star caused by a planet passing across its face. In astronomy, these events are termed transits, and they cause distinct u-shaped dips in the lightcurve—a plot of observed brightness versus time—of their host star. In recent years, the Kepler Space Telescope has provided lightcurve data on a fixed group of stars that is unprecedented in precision. Our research is primarily concerned with searching released Kepler data for previously undiscovered exoplanets. Due to the vast quantity of information, we have developed a pipeline of computer code to expedite the search process. The code, written in python, detrends variations in quiescent star brightness to normalize each lightcurve around a fixed, flat value. This readies the data for input to a Quasi-Periodic Automated Transit Search algorithm (QATS). Thus far, we have identified a handful of planet candidates as well as a number of undocumented binary star systems. Current and future tasks involve automating QATS output classification to further improve the efficiency of the planet finding process.

M dwarf stars, which are smaller, dimmer, and redder than our Sun, are the most common type of star in our galaxy. Like our Sun, these stars exhibit activity due to inherently strong magnetic fields at their surfaces. In M dwarfs, this activity is often classified by the emission line strength of the first transition of the hydrogen Balmer series (H alpha). We examine a sample of five equal-mass M dwarf wide binaries; these “twin” stars should have nearly identical stellar properties and therefore have very similar spectral features. We hypothesize that these stars should exhibit nearly identical properties in H alpha. If our hypothesis proves false, it means there are unexpected dynamics present in the binary system. In initial observations to classify these objects, we found that the M dwarfs in each binary, which were twins in every other way, showed very different levels of H alpha emission. To examine the range of H alpha line strengths we obtained a time series of optical spectra using the Astrophysical Research Consortium’s 3.5-meter telescope at Apache Point Observatory in New Mexico. In each binary, the slightly less massive star exhibits stronger mean H alpha, consistent with large survey results. Using data from 70 hours over 14 nights, we determined our stars have a characteristic variability timescale of around 2 hours; indicating our sample is active on shorter timescales than the typical rotational period.

The initial mass distribution for exoplanet systems, prior to the onset of planet-planet scattering, has yet to be adequately constrained. Scattering has previously explained a broad range of observed properties, such as large eccentricities, packing, and mean-motion resonances, and hence is a promising theory. We present the results of numerical simulations of scattering-produced multiple planet systems arising from different initial power law mass distributions. We explore which of these power law distributions most accurately reproduces the observed mass distribution, thereby constraining the initial mass function.

In the search for habitable planets, density is crucial in allowing us to determine whether a planet is terrestrial or gaseous. We developed a method of measuring the flux from a star during a planetary transit to constrain the density and the mass of the planet. This method depends on our ability to detect a moon in the transit and chart minor fluctuations in moon velocity and moon position with respect to the planet. To determine the precision with which we can measure the density of a planet, we have created a model which produces a synthetic light curve from which we can attempt to extrapolate planet parameters. However, we have found that the accuracy of planet density calculations is highly dependent on the signal to noise ratio of the sample due to the fact that moons have very small signals. We explore methods with which to detect moon signals to improve upon our ability to determine the density. It may still be necessary to combine our efforts with other methods, such as spectra analysis of Doppler shifts, to confidently differentiate potential life-bearing planets from those which are not habitable.

The inferior olive is heavily involved in implicit timing, the unconscious encoding of timing of sensory or motor events. Performance of these tasks relies on synchronous output from ensembles of neurons in the inferior olive, which are electrotonically coupled to one another via gap junctions. Previous attempts to understand coupling properties in the inferior olive have relied on technically challenging dual whole-cell recordings. Here, I demonstrate an optogenetic approach which provides rapid evaluation of electrotonic coupling in the inferior olive using femtosecond pulsed infrared stimulation of olivary cells expressing the light-activated cation channel channelrhodopsin-2 (ChR2 H134R). Targeted expression of ChR2 in olivary neurons was achieved through the Ai32 mouse line engineered at the Allen Institute for Brain Science, which were crossed with mice expressing Cre-recombinase targeted to the pancreatic transcription factor 1a (Ptf1a) locus. Parasagittal brainstem slices were prepared from young (P20-P40) Ptf1a-Ai32 positive mice. Electrodes were guided under IR-DIC for whole-cell recording of a single olivary neuron. Neighboring cells were stimulated using 920 nm light (<1 mW/µm² average power), in which a single infrared beam was split into 64 beamlets and distributed evenly over the neighboring cell's cross sectional area (100-400 µm²). Coupling properties determined by optogenetic stimulation of neighboring cells replicated previous results produced by dual whole-cell recordings (CC=1-10%). Furthermore, optogenetic evaluation of coupling following pharmacological manipulation of olivary neurons were consistent with previous findings. This optogenetic approach will provide a rapid and efficient method for future exploration of coupling properties in the inferior olive, which may accelerate the study of their involvement in pathologies such alcoholism, autism and sudden infant death syndrome.

All cells including bacteria exhibit an intricate spatial organization that is essential for cellular function. The mechanisms by which this ultra structural organization is established and maintained are not yet understood. The resolution limit of conventional wide-field fluorescence microscopy is set to 250nm by the diffraction limit, however the building blocks cellular ultra-structure, protein, are typically a few nanometers in size. Therefore, in order to probe the cell-machinery that gives rise to the organization of Escherichia coli chromosome, I use a super resolution fluorescence microscopy technique called PhotoActivation Localization Microscopy (PALM). I am able to resolve DNA structures with a resolution near ~20nm by labeling short sections of E. coli chromosome with a photoactivatable fluorescent protein. I then relate the measured size of chromosome sections to known physical parameters of DNA in order to asses the viability of various polymer models of DNA, which will lead to a better understanding of the physical factors that lead to structure in E. coli.

Astronomers do not yet completely understand how galaxies evolve. Current leading theories propose that spiral galaxies merge and the result is an ultra-luminous infrared galaxy or ULIRG, which is a galaxy with an active galactic nuclei (AGN) that is obscured by warm dust and gas. After the ULIRG phase, it is thought that the galaxy becomes a quasar after a blowout stage occurs. The blowout stage is when the huge energy output from the accretion process of material falling into the central black hole expels the gas that was previously obscuring the central quasar. The blowout stage would be short-lived, however, and therefore difficult to directly observe, so evidence of this process is scarce. In order to study the blowout stage, we obtained 2-D K-band integral field data with SINFONI (Spectrograph for Integral Field Observations in the Near Infrared) on the Very Large Telescope for a sample of six quasars that are divided into pre- and post–blowout by comparing their ratios of infrared luminosity to the luminosity of the optical 'big blue bump’. We measured the spatial distribution and column density of the warm molecular gas but did not find the correlation of these quantities predicted by blowout models. To further explore the relationship between post- and pre-blowout galaxies, we fit the luminosity profiles of the molecular gas and compare this to the profiles of the stellar population which traces the gravitational potential.

Seyfert galaxies are a type of galaxy that is part of a larger class called active galactic nuclei (AGN) in which the central supermassive black hole is accreting surrounding material. On large scales, Seyfert galaxies look identical to quiescent galaxies in which the supermassive black hole is inactive. However, on a smaller scale, around 10 – 10³ parsecs, we are now starting to detect differences in the molecular gas and stellar properties that can help us reach our goal of determining what the key differences are between the Seyfert galaxies and the quiescent galaxies and what results in the generation of an AGN. One of these differences could be star formation at the nucleus of the galaxy. To determine if this is a factor, we can use spatially resolved 2-D spectra to detect any Brackett Gamma (Brγ) emission within the central 10³ pc. For galaxies that have Brγ emission, we can measure the equivalent width of the Brγ line and, through comparison with stellar population evolution models, constrain the age of the stars. A potential complication with using the Brγ line is that there can be an additional broad component of the line generated by high velocity clouds very near the central black hole that is not associated with star formation. We minimize the impact of this broad component by fitting and removing it to isolate the narrow line emission of interest. The age can also be further constrained by estimating the supernova rate and the mass-to-light ratio. We have found that Brγ is significantly more prominent in Seyfert galaxies than in quiescent galaxies, suggesting that there is more active star formation in the nuclear region of Seyfert galaxies. Constraining the age of this stellar population will determine the role of these stars in fueling the central AGN in these galaxies.

A proto-planetary disk is a disk of gas and dust that surrounds a star that is still in the early stages of evolution. This disk contains the gas that accretes onto the proto-star and also contains the dust and gas from which planets form. Unfortunately the star is a much brighter than the disk and so direct imaging of the disk is difficult and time consuming, but can be accomplished using a coronagraph. To help interpret coronagraphic imagery of the protoplanetary disk system AB Aur, we created 3D models of the system using the Monte Carlo code of Whitney et al. 2002. We compared the observed the spectral energy distribution (SED) of the system, compiled from observed data reported by Robitaille et al. 2006, with predictions from our Monte Carlo model. An SED is a plot of the brightness versus wavelength of a star. We tested other variables like the composition of the disk, and the percentage of the disk that is composed of small grains and large grains, etc. We discuss how changing each of these variables influenced the resultant SED and model image of the AB Aur system; and hence influences our ability to study the process of planet formation around young stars.

Variable stars are stars that fluctuate in brightness over time, usually with sinusoidal patterns. We can plot the brightness of variables over time to create light curves, which allow us to examine the periodicity of the stars. SX Phe variables are a specific type of star that have not been extensively studied and classified. We examined seven SX Phe candidates in order to more precisely determine their light curves. The periods of the candidates had been roughly estimated with data from the LINEAR survey. The goal of this project was to determine these periods more precisely and to image the stars in multiple filters, which will tell us more about their properties. At the University of Washington Manastash Ridge Observatory (MRO), these seven candidate SX Phe stars were observed in the Sloan g’ and r’ filters over at least 1.5 periods. Photometric images of the candidates were obtained from these observations, and light curves were produced. It was determined that the majority of candidates have periods of variability of about 1.35 hours, almost half as long as previously hypothesized. Further analysis of these more accurate light curves is needed to classify the candidates as SX Phe stars.

The reduction of CO₂ has become a global priority as the concerns of climate change and the adverse effects of atmospheric carbon dioxide on the environment continue to rise. One method of reducing CO₂ emissions is through conversion and utilization as a chemical feedstock. CO₂ is cheap, nontoxic, and can be recycled to produce valuable new products, making it an attractive feedstock. The increasing importance of CO₂ utilization processes requires a better understanding of the underlying mechanisms of its conversion. The industrial conversion of CO₂ is typically achieved using a heterogeneous catalyst, usually consisting of small transition metal particles supported on a high surface area metal oxide. Our project focuses on elucidating the mechanism of the reverse water-gas shift (RWGS) reaction on platinum, an extensively studied catalyst with a highly active surface. Our goals are (1) to quantitatively measure the RWGS rate under conditions of low H coverage and (2) to compare the measured rate to the rate of CO₂ dissociation (the rate-limiting step according to the surface redox mechanism) and to the theoretical rate calculated using a micro-kinetic model based on the associative mechanism. The information we gather from the investigation will clarify whether the RWGS reaction proceeds on platinum via the surface redox mechanism or the associative mechanism.

Planetary Nebulae (PNe) are the final stages of stellar evolution for the majority of stars including our Sun. They consist of a very hot white dwarf surrounded by a shell of gas that was ejected from the progenitor star as it aged. The white dwarf produces ultra-violet photons that ionize the gas in the shell producing the bright structures that we see in images produced by the Hubble Space Telescope (HST). Classical models that predict the ionization structure of planetary nebulae generally assume constant gas density in the shell. The simple symmetry of the models allows them to adopt a 1-dimensional (1-D) geometry for the calculated ionization structure of the shell. Our HST images allow us to test these models. We obtained HST images using the light from ionized hydrogen (H⁺), doubly ionized oxygen (O⁺⁺) and singly ionized nitrogen (N⁺). We use H⁺ to find the full extent of the ionized nebula, O⁺⁺ to select one of the key ionization volumes within it, and N⁺ to study the region where the ionization state of the gas changes from fully ionized to neutral. From those images we generated ratios of N⁺/H⁺ and O^++/H⁺. These ratios are being used to test the veracity of and identify departures from theoretical models.

AB Aur is a protostar with a surrounding protoplanetary disk. By taking coronagraphic images of AB Aur using an occulting mask to block out the star in order to get a more detailed look at the young circumstellar disk we are able to analyze the potential formation of any extrasolar planets. Because it is unclear where the exact center of the star is behind the occulting mask, we simulated the effects of mis-centered stars by shifting 24 individual images of the disk 4 times at different pixel shifts. Using 14 areas of interest we were able to compare the intensity changes for each final shifted image. Any significant variations in the intensity graph indicated the region was not an actual structure. We concluded there was a spiral arm forming on the right side of the disk and the gap above the star was real and not strongly affected by any mis-centering of the central star behind the corongraphic mask.

Many plants, as part of their growth process, accumulate groundwater-derived silica that is deposited into inter- and intracellular spaces, forming what are known as phytoliths. Due to a combination of preservational and diagnostic characteristics, phytoliths found in the fossil record serve as a powerful paleontological tool for the reconstruction of past environments and climates. For this study, rock samples containing phytoliths were collected from a site called Everson Creek in southwest Montana, once part of the Great Plains region of the United States, which spans in age from 25.3 to 24.5 million years and corresponds to an interval of warming worldwide. The samples have been processed for phytoliths using heavy liquid flotation, whereby silica bodies are separated from other material by means of their unique density. Currently, the phytoliths are in the process of being counted and divided into various diagnostic groups according to morphology. The results of these counts, when viewed in temporal order throughout the site, will shed light on the floral and climatic history of the region based on the prominent plant groups and their growth preferences. This research, which covers a time interval previously unstudied for phytoliths aims to clarify the timing of the rise to dominance of open-habitat grasses in the region, a subject that is currently disputed in the literature. The spread of grasslands is an important event in plant history because it represents the development of open habitats and is intimately linked to the expansion and evolution of various other biota. Since grasses are large producers of highly diagnostic phytoliths, any change in their ecological role will easily be seen in this study.

Solar cells, through their ability to convert energy from light directly into electricity, pose a promising alternative for supplying our world’s growing demand for clean affordable energy. Many factors governing the efficiency of these photovoltaic devices are still being explored and improved upon through methods aimed at boosting photo-voltages, improving energy-conversion efficiency, and finding materials accessible for large-scale production and implementation. Here, I investigate the potential of a new type of solar cell that utilizes electron-impurity Auger de-excitation. I will discuss the effect of Auger de-excitation observed in Mn doped CdS quantum dots and explore the potential for boosting the photo-voltage via the harvesting of hot electrons. I will explain the processes involved in both synthesizing Mn:CdS quantum dots and fabricating quantum dot-based solid-state devices. I will show preliminary results from photoluminescence quenching measurements used to quantify Auger de-excitation in fabricated solid-state devices as well as device properties and characterization measurements. In the future, full-cell PV devices will be constructed and tested against the efficiencies of today’s leading solar cells.

Orbital spectroscopy allows for the analysis of surface composition on the planet Mars, and is providing evidence for the presence of liquid water throughout the planet’s history. We use hyperspectral images from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) aboard the Mars Reconnaissance Orbiter (MRO) to identify a variety of compositions on the planet. These compositions can provide information about the conditions present at the time of their formation. In many cases, as where carbonates are identified, these compositions are clear evidence for the presence of liquid water in the martian past. We identify minerals by their unique absorptions at specific wavelengths through the examination of CRISM surface reflectance data across 438 wavelengths from 1.0 to 3.9 microns. For identification, the CRISM spectra are matched to spectra of laboratory samples from Earth. However, there are differences between these spectra that give some new insight into the combination of minerals present and their formation process. By applying factor analysis to the CRISM dataset where the spectral signature of the mineral components vary independently from one another, the measurements can be expressed as a linear sum of the components. We have applied this target transformation and factor analysis technique to CRISM spectra to identify and isolate the various mineral components present, even under circumstances where the mineral components are only present in minor abundances and mixed with other spectral signatures. Because the entire dataset is used to retrieve mineral spectral signatures, this analysis greatly reduces instrumental error to provide well-defined CRISM spectra. Ultimately, by applying our data analysis technique to the global CRISM dataset, we will have a stronger and more detailed understanding of surface composition and aqueous processes on Mars. Based on these processes we can then invoke different conditions conducive for the development of life on Mars.

The Ihara Zeta Function (IZF) of a finite graph encodes its spectral, combinatorial and number theoretic properties. Our aim is to calculate the IZF of the Cayley graph of the modular group PSL(2,Z), which can be thought of as a special group of square matrices. Since this group plays a central role in number theory and other areas of mathematics and physics, we hypothesize that the zeta function will reflect important information about modular forms and elliptic curves. Our previous research has yielded an algorithm that computes the IZF of a sequence of finite approximations of this group, but it does not give the IZF of the entire graph. The IZF can be expressed as a product of L-functions, which encode how successive graphs in the sequence are related. Our ultimate aim is to use the L-functions of the finite approximations to compute the IZF of the modular group. We are currently exploring L-functions of simpler Cayley graphs, in the hope that the methods can be generalized to calculate the IZF of PSL(2,Z).

More than 50 percent of stars are found in binary systems. A cataclysmic variable star is a binary system consisting of a white dwarf and a larger, cooler star in an orbit with a period of only a few hours. These stars are so close that the white dwarf distorts the gravitational field of the other star and mass is transferred from the cool star to the white dwarf via an accretion disk. The defining characteristic of the type of cataclysmic variable called dwarf novae is that they irregularly increase and decrease in brightness. The increases (called outbursts) are caused by an instability in the accretion disk that causes an increase in accretion. After an outburst, these stars steadily decline in brightness until they return to their original state. However, the subgroup of dwarf novae called Z Cam systems sometimes become stuck in a state called a standstill, where they stay at a brightness near outburst level, and then decline to their original level. Using data taken at Kitt Peak National Observatory and Apache Point observatory over a series of five months, we were able to analyze spectra of two unusual objects as they go through their outbursts. We can find out what state they are in by comparing their spectra to light curves from the American Association of Variable Star Observers. What is unusual about these objects is that rather than fade to their original state after standstills, they go up to another outburst. Using these spectra, we hope to find the accretion rates of the stars at standstill, and then compare to other stars of the same type to better understand why they have this peculiar behavior.

Bacterial conjugation is the process of transferring genetic material from one cell to another. In the case of F-plasmid of Escherichia coli, the conjugation system is composed of inter-membrane proteins as well as hairlike appendages called pili encoded by the plasmid. Current interest in the characterization of F-plasmid lies with its ability to not only transfer itself to other cells but also its potential to mobilize auxiliary genes, such as antibiotic resistance, that yield some selective advantage. However, many basic details about the F-plasmid system, such as how donor cells recognize recipients and the function of the protruding pili, remain unknown. Through the use of an optical tweezer setup, I am able to isolate individual, fluorescently labeled E. coli cells in close proximity to each other. Once in close proximity, I will monitor the forces applied by donor cells on recipient cells and compare those forces to the forces potentially applied by donor cells on other donor cells. In addition, by utilizing the same optical tweezer setup, I will explore the statistical behavior of F-plasmid transfer as a function of cell-to-cell separation to investigate the potential function of the pili as transfer conduits.

Despite the numerous studies of the bacteria E. Coli, the basic motion of macromolecules confined to the cellular cytoplasm, such as mRNA, remains uncharacterized. I employ a technique called fluorescent correlation microscopy, which consists of binding synthesized mRNA with fluorescent proteins, imaging the cell throughout its lifetime, and analyzing the images using statistical autocorrelation. This technique allows me to determine the diffusion constant (D) as a function of cellular location while bypassing the error caused by higher order analysis. We predict that D is primarily dependent on the molecular crowding at its position, and there exists a tendency for mRNA to gather in the less crowded spaces in the cell, e.g. at the poles.

Ultracold molecules are a new frontier in atomic physics that have many possible applications which include tests of fundamental physical theories and the development of quantum information science. One method of creating such molecules is through the process of photo-association (PA), where two ultracold atoms are optically excited into a bound molecular state. We will present the design and construction of an extended cavity laser diode system that will be used for PA of ultracold Lithium (Li) and Ytterbium (Yb) atoms. The exact energies for molecule formation are not known a-priori, so the laser has to be tunable over a wide range of frequencies near the wavelength of 556nm. To maximize the “mode hope free” (MHF) range where the laser frequency varies smoothly, we will simultaneously vary the current powering the diode and the length of the laser cavity. Once the MHF range has been maximized, the laser will be used in PA spectroscopy in order to form Li-Yb molecules and characterize their energy structure.

Graphene is a novel two-dimensional carbon material whose recent discovery has been awarded the 2010 Nobel Prize in Physics. The extraordinary electronic and mechanical properties of graphene such as its extremely high electron mobility and record breaking thermal conductivity have made it a promising candidate for countless applications, including integrated circuits, solar cells, and ultracapacitors. Graphene has also demonstrated usefulness in biological applications, and it was recently shown that mesenchymal stem cells cultured on the surface of graphene experience accelerated differentiation into bone cells. This has motivated research into the interaction of graphene with other types of cells, and we investigate the effects of culturing cardiomyocytes (heart muscle cells) on the surface of graphene. With cardiovascular disease being the leading cause of death globally there is currently a large effort to develop treatments based on engineered heart tissue, but no tissue engineering methods have thus far been able to produce cells that are sufficiently mature to provide the force generation necessary in a beating heart. Two methods currently showing promise for the maturation of cardiomyocytes are designed to mimic the environment of native heart tissue using electrical stimulation, and culturing on micropatterned substrates.  By culturing cardiomyocytes on the surface of micropatterned graphene that is electrically contacted through gold electrodes, we explore graphene’s potential to act as a versatile platform that could combine both methods.