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MEDIA SENSATIONALISM AND ITS IMPLICATIONS ON THE PUBLIC UNDERSTANDING OF SCIENCE
Title
MEDIA SENSATIONALISM AND ITS IMPLICATIONS ON THE PUBLIC UNDERSTANDING OF SCIENCE.
Creator
Barsoum, Christopher, Colwell, Joshua, University of Central Florida
Abstract / Description
Myths, misinformation, and sensationalism. These are common enemies that directly inhibit the public understanding of science. In particular, the media is often responsible for mishandling or otherwise misrepresenting scientific information, historically and presently speaking. Many sources can combat the public understanding of science through pseudoscientific means. This includes but is not limited to religion, the media, politics, or just simple hearsay. For example, Young Earth...
Show moreMyths, misinformation, and sensationalism. These are common enemies that directly inhibit the public understanding of science. In particular, the media is often responsible for mishandling or otherwise misrepresenting scientific information, historically and presently speaking. Many sources can combat the public understanding of science through pseudoscientific means. This includes but is not limited to religion, the media, politics, or just simple hearsay. For example, Young Earth creationism is deeply rooted in Christian theology, but the beliefs hold no scientific basis. Yet, almost half of Americans still believe in Young Earth creationism. Another such example is anti-vaccination campaigns due to fears of autism-spectrum related disorders. In this case, falsified claims were given illegitimate credibility through the media, and the claims are widely and erroneously contentious to this day. The purpose of this research was to investigate the relationship between an individual's ability to dictate science from pseudoscience and their exposure to sensationalized media. Through means of surveying the university level population, relationships were drawn between how many pseudoscientific beliefs an individual may have versus how they interact with science and the media. The results of the survey showed a general lack of interest or care for science with more pseudoscientific beliefs, yet failed to draw a relationship between pseudoscientific beliefs and a sensationalized media.
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Date Issued
2014
Identifier
CFH0004674, ucf:45296
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFH0004674
FINE-SCALE STRUCTURES IN SATURN'S RINGS:WAVES, WAKES AND GHOSTS
Title
FINE-SCALE STRUCTURES IN SATURN'S RINGS:WAVES, WAKES AND GHOSTS.
Creator
BAILLIE, Kevin, Colwell, Joshua, University of Central Florida
Abstract / Description
The Cassini mission provided wonderful tools to explore Saturn, its satellites and its rings system. The UVIS instrument allowed stellar occultation observations of structures in the rings with the best resolution available (around 10 meters depending on geometry and navigation), bringing our understanding of the physics of the rings to the next level. In particular, we have been able to observe, dissect, model and test the interactions between the satellites and the rings. We first looked at...
Show moreThe Cassini mission provided wonderful tools to explore Saturn, its satellites and its rings system. The UVIS instrument allowed stellar occultation observations of structures in the rings with the best resolution available (around 10 meters depending on geometry and navigation), bringing our understanding of the physics of the rings to the next level. In particular, we have been able to observe, dissect, model and test the interactions between the satellites and the rings. We first looked at kilometer-wide structures generated by resonances with satellites orbiting outside the main rings. The observation of structures in the C ring and their association with a few new resonances allowed us to estimate some constraints on the physical characteristics of the rings. However, most of our observed structures could not be explained with simple resonances with external satellites and some other mechanism has to be involved. We located four density waves associated with the Mimas 4:1, the Atlas 2:1, the Mimas 6:2 and the Pandora 4:2 Inner Lindblad Resonances and one bending wave excited by the Titan -1:0 Inner Vertical Resonance. We could estimate a range of surface mass density from 0.22 +/- 0.03 to 1.42 +/- 0.21 gcm^-2 and mass extinction coefficient from 0.13 +/- 0.03 to 0.28 +/- 0.06 cm^2 g^-1. These mass extinction coefficient values are higher than those found in the A ring (0.01 - 0.02 cm^2 g^-1) and in the Cassini Division (0.07 - 0.12 cm^2 g^-1 from Colwell et al. (2009), implying smaller particle sizes in the C ring. We can therefore imagine that the particles composing these different rings have either different origins or that their size distributions are not primordial and have evolved differently. We also estimate the mass of the C ring to be between 3.7 +/- 0.9 x 10^16 kg and 7.9 +/- 2.0 x 10^16 kg, equivalent to a moon of 28.0 +/- 2.3 km to 36.2 +/- 3.0 km radius (a little larger than Pan or Atlas) with a density comparable to the two moons (400 kg m^-3). From the wave damping length and the ring viscosity, we also estimate the vertical thickness of the C ring to be between 1.9 +/- 0.4 m and 5.6 +/- 1.4 m, which is consistent with the vertical thickness of the Cassini Division (2 - 20 m) from Tiscareno et al. (2007) and Colwell et al. (2009). Conducting similar analysis in the A, B rings and in the Cassini Division, we were able to estimate consistent masses with previous works for the these rings. We then investigated possible interactions between the rings and potential embedded satellites. Looking for satellite footprints, we estimated the possibility that some observed features in the Huygens Ringlet could be wakes of an embedded moon in the Huygens gap. We discredited the idea that these structures could actually be satellite wakes by estimating the possible position of such a satellite. Finally, we observed a whole population of narrow and clear holes in the C ring and the Cassini Division. Modeling these holes as depletion zones opened by the interaction of a moonlet inside the disk material (this signature is called a "propeller"), we could estimate a distribution of the meter-sized to house-sized objects in these rings. Similar objects, though an order of magnitude larger, have been visually identified in the A ring. In the C ring, we have signatures of boulders which sizes are estimated between 1.5 and 14.5 m, whereas similar measures in the Cassini Division provide moonlet sizes between 0.36 and 58.1 m. Using numerical simulations for the propeller formation, we estimate that our observed moonlets belong to a population of bigger particles than the one we thought was composing the rings: Zebker et al. (1985) described the ring particles population as following a power-law size distribution with cumulative index around 1.75 in the Cassini Division and 2.1 in the C ring. We believe propeller boulders follow a power-law with a cumulative index of 0.6 in the C ring and 0.8 in the Cassini Division. The question of whether these boulders are young, ephemeral and accreted inside the Roche limit or long-lived and maybe formed outisde by fragmentation of a larger body before migrating inward in the disk, remains a mystery. Accretion and fragmentation process are not yet well constrained and we can hope that Cassini extended mission will still provide a lot of information about it.
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Date Issued
2011
Identifier
CFE0003947, ucf:48681
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0003947
Determining the Small-scale Structure and Particle Properties in Saturn's Rings from Stellar and Radio Occultations
Title
Determining the Small-scale Structure and Particle Properties in Saturn's Rings from Stellar and Radio Occultations.
Creator
Jerousek, Richard, Colwell, Joshua, Britt, Daniel, Fernandez, Yan, Hedman, Mathew, University of Central Florida
Abstract / Description
Saturn's rings consist of icy particles of various sizes ranging from millimeters to several meters. Particles may aggregate into ephemeral elongated clumps known as self-gravity wakes in regions where the surface mass density and epicyclic frequency give a Toomre critical wavelength which is much larger than the largest individual particles (Julian and Toomre 1966). Optical depth measurements at different wavelengths can be used to constrain the sizes of individual particles (Zebker et al....
Show moreSaturn's rings consist of icy particles of various sizes ranging from millimeters to several meters. Particles may aggregate into ephemeral elongated clumps known as self-gravity wakes in regions where the surface mass density and epicyclic frequency give a Toomre critical wavelength which is much larger than the largest individual particles (Julian and Toomre 1966). Optical depth measurements at different wavelengths can be used to constrain the sizes of individual particles (Zebker et al. 1985, Marouf et al. 1983) while measurements of optical depths spanning many viewing geometries can be used to determine the properties of self-gravity wakes (Colwell et al. 2006, 2007, Hedman et al. 2007, Nicholson and Hedman 2010, Jerousek et al. 2016). Studies constraining the parameters of the assumed power-law particle size distribution have been attempted (Zebker et al. 1985, Marouf et al. 1983) but have not yet accounted for the presence of self-gravity wakes or the much larger elongated particle aggregates seen in Cassini Imaging Subsystem (ISS) images and commonly referred to as (")straw("). We use a multitude of Cassini stellar occultations measured by UVIS (Ultraviolet Imaging Spectrograph) and VIMS (Visual and Infrared Mapping Spectrometer) together with Cassini's RSS (Radio Science Sub System) X-band, Ka-band, and S-band radio occultations to better constrain the particle size distribution throughout Saturn's main ring system, including regions where self-gravity wakes have a significant effect on the measured optical depth of the rings.
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Date Issued
2018
Identifier
CFE0007019, ucf:52029
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0007019
Spectral Study of Asteroids and Laboratory Simulated Asteroid Organics
Title
Spectral Study of Asteroids and Laboratory Simulated Asteroid Organics.
Creator
Hargrove, Kelsey, Colwell, Joshua, Fernandez, Yan, Britt, Daniel, Kelley, Michael, University of Central Florida
Abstract / Description
We investigate the spectra of asteroids at near- and mid-infrared wavelengths. In 2010 and 2011 we reported the detection of 3 ?m and 3.2-3.6 ?m signatures on (24) Themis and (65) Cybele indicative of water-ice and complex organics [1] [2] [3]. We further probed other primitive asteroids in the Cybele dynamical group and Themis family, finding diversity in the shape of their 3 ?m [4] [5] [6] and 10 ?m spectral features [4]. These differences indicated mineralogical and compositional...
Show moreWe investigate the spectra of asteroids at near- and mid-infrared wavelengths. In 2010 and 2011 we reported the detection of 3 ?m and 3.2-3.6 ?m signatures on (24) Themis and (65) Cybele indicative of water-ice and complex organics [1] [2] [3]. We further probed other primitive asteroids in the Cybele dynamical group and Themis family, finding diversity in the shape of their 3 ?m [4] [5] [6] and 10 ?m spectral features [4]. These differences indicated mineralogical and compositional variations within these asteroid populations. Also in the mid-infrared region we studied a larger population of asteroids belonging to the Bus C, D, and S taxanomic classes to understand the relationship between any mineralogy and hydration inferred in the visible and near- infrared with the shape, strength, and slope of the 10 ?m emission. We have discovered that at least 3 of the main Bus taxanomic groups (Cs, Ds, and Ss as defined by their visible spectra) clearly cluster into 3 statistically distinct groups based on their 8-13 ?m spectra. Additionally we have attempted to simulate in a laboratory the possible organic compounds we have detected on two asteroids, using various mixtures containing aromatic and aliphatic hydrocarbons. We find that asteroid (24) Themis and (65) Cybele have ?CH2/?CH3 and NCH2/NCH3 ratios similar to our 3- methylpentane, propane, and hexane residues, suggesting that the organics on these asteroids may be short chained and/or highly branched. The ?CH2/?CH3 and NCH2/NCH3 for asteroid(24)Themis are most consistent with the DISM, and some carbonaceous chondrites. The band centers of the C-H stretch absorptions indicate that both asteroids may have aliphatic carriers chemically bonded to electronegative groups (i.e. aromatics), and some that are not. We also detect a 3.45 ?m feature in the spectra of both asteroids that is present in several dense molecular clouds. Our results suggest an interstellar origin for the organics on (24) Themis, and likely (65) Cybele. The differences in the organics of Themis and Cybele are likely related to variations in thermal processing, irradiation and/or formation region in the solar nebula.
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Date Issued
2015
Identifier
CFE0005624, ucf:50201
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0005624
Saturn's Rings: Measuring Particle Size Distributions Using Cassini UVIS Occultation Data
Title
Saturn's Rings: Measuring Particle Size Distributions Using Cassini UVIS Occultation Data.
Creator
Becker, Tracy, Colwell, Joshua, Fernandez, Yan, Campins, Humberto, Showalter, Mark, Klemm, Richard, University of Central Florida
Abstract / Description
Since its arrival to Saturn in 2004, the Cassini spacecraft has utilized its suite of sophisticated instruments to further our understanding of the Saturnian ring system. We analyze occultation data from Cassini's Ultraviolet Imaging Spectrograph (UVIS) in order to measure the particle size distribution and place limits on the minimum particle sizes in Saturn's rings.Throughout the ring system, particle accretion is countered by collisional and tidal disruption and Keplerian shear. Therefore,...
Show moreSince its arrival to Saturn in 2004, the Cassini spacecraft has utilized its suite of sophisticated instruments to further our understanding of the Saturnian ring system. We analyze occultation data from Cassini's Ultraviolet Imaging Spectrograph (UVIS) in order to measure the particle size distribution and place limits on the minimum particle sizes in Saturn's rings.Throughout the ring system, particle accretion is countered by collisional and tidal disruption and Keplerian shear. Therefore, the particle size distribution of the rings is continually evolving. The presence of sub-centimeter particles, which have short lifetimes due to these processes, is indicative of ongoing dynamics in the rings. Sub-centimeter-sized particles efficiently diffract light at ultraviolet wavelengths, and thus produce signatures of diffraction in the occultation data. The shape and intensity of the diffraction signatures are indicative of the sizes of the particles that produce them. The UVIS wavelength bandpass, 51.2 - 180 nm, contains the shortest wavelengths of the Cassini instruments, making it most sensitive to the smallest particles in the rings. We have developed a computational model that reconstructs the geometry of a UVIS observation and produces a synthetic diffraction signal for a given truncated power-law particle size distribution, which we compare with the observed signal. We implement this model for two sets of observations: (1) diffraction spikes at sharp ring edges during stellar occultations and (2) the light curve due to attenuated and diffracted sunlight by particles in Saturn's F ring during solar occultations. Near sharp ring edges, ring particles can diffract light such that there is a measurable increase in the signal of an unocculted star exterior to the ring. In Saturn's A ring, diffracted light can augment the stellar signal by up to 6% and can be detected tens of kilometers radially beyond the edge. The radial profile of the diffraction signal is dependent on the size distribution of the particle population near the ring edge. These diffraction signals are observed at sharp edges throughout Saturn's rings, although in this work we focus on diffraction at the outer edge of Saturn's A ring and at the edges of the Encke Gap. We find an overall steepening of the power-law size distribution and a decrease in the minimum particle size at the outer edge of the A ring when compared with the Encke Gap edges. This suggests that interparticle collisions caused by satellite perturbations in the region result in more shedding of regolith or fragmentation of particles in the outermost parts of the A ring. We rule out any significant population of sub-millimeter-sized particles in Saturn's A ring, placing a lower limitation of 1-mm on the minimum particle size in the ring.We also model the light curves produced as Saturn's F ring occults the Sun. We consider both the attenuated signal and the light diffracted by the particles in the ring during the occultation. Five of the eleven solar occultations analyzed show a clear signature of diffracted light that surpasses the unocculted solar signal. This includes a misaligned solar occultation that placed most of the solar disk outside of the instrument's field of view, reducing the solar signal by 97.5% and resulting in the serendipitous detection of diffracted light. We measure a large variation in the the size distribution of the particles that fill the broad, ~500 km region surrounding the F ring core. We find that smaller particles ((<) 50 micrometers) are present during solar occultations for which diffraction was detected, and place a lower limit on the minimum particle size of 100 micrometers for occultations during which diffraction was not detected. A comparison with images of the F ring observed by the Cassini Imaging Science Subsystem near the times of the occultations reveals that the detections of small particles in the UVIS data correspond with locations of collisional events in the F ring. This implies that collisions within the F ring core replenish the sub-millimeter-sized dust in the 500-km region that encompasses the F ring core.
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Date Issued
2016
Identifier
CFE0006073, ucf:50940
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0006073
Studying Short-Period Comets and Long-Period Comets Detected by WISE/NEOWISE
Title
Studying Short-Period Comets and Long-Period Comets Detected by WISE/NEOWISE.
Creator
Kramer, Emily, Fernandez, Yan, Colwell, Joshua, Kokoouline, Viatcheslav, Klemm, Richard, Lisse, Carey, University of Central Florida
Abstract / Description
The Wide-field Infrared Survey Explorer (WISE) mission surveyed the sky in four infrared wavelength bands (3.4, 4.6, 12 and 22 ?m) between January 2010 and February 2011. During the mission, WISE serendipitously observed 160 comets, including 21 newly discovered objects. About 89 of the comets observed by WISE displayed a significant dust tail in the 12 and 22 ?m (thermal emission) bands, showing a wide range of activity levels and dust morphology. Since the observed objects are a mix of both...
Show moreThe Wide-field Infrared Survey Explorer (WISE) mission surveyed the sky in four infrared wavelength bands (3.4, 4.6, 12 and 22 ?m) between January 2010 and February 2011. During the mission, WISE serendipitously observed 160 comets, including 21 newly discovered objects. About 89 of the comets observed by WISE displayed a significant dust tail in the 12 and 22 ?m (thermal emission) bands, showing a wide range of activity levels and dust morphology. Since the observed objects are a mix of both long-period comets (LPCs) and short-period comets (SPCs), differences in their activity can be used to better understand the thermal evolution that each of these populations has undergone. For the comets that displayed a significant dust tail, we have estimated the sizes and ages of the particles using dynamical models based on the Finson-Probstein method [Finson and Probstein, 1968]. For a selection of 40 comets, we have then compared these models to the data using a novel tail-fitting method that allows the best-fit model to be chosen analytically rather than subjectively. For comets that were observed multiple times by WISE, the particle properties were estimated separately, and then compared. We find that the dust tails of both LPCs and SPCs are primarily comprised of ?mm-cm sized particles, which were the result of emission that occurred several months to several years prior to the observations. The LPCs nearly all have strong emission close to the comet's perihelion distance, and the SPCs mostly have strong emission close to perihelion, but some have strong emission well before perihelion.
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Date Issued
2014
Identifier
CFE0005823, ucf:50938
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0005823
Dynamical Formation of Protoplanetesimals
Title
Dynamical Formation of Protoplanetesimals.
Creator
Whizin, Akbar, Colwell, Joshua, Fernandez, Yan, Klemm, Richard, Lewis, Mark, Moore, Brian, University of Central Florida
Abstract / Description
The seeds of planetesimals that formed in the gaseous protoplanetary disk (PPD) have many barriers to overcome in their growth from millimeter to meter-sized and larger bodies. Centimeter-sized aggregates are weakly bound and self-gravity is almost non-existent so surface forces play a critical role in holding small loosely-bound rubble-piles together. Their orbital motions and effects form disk processes impart relative velocities leading to collisions so understanding the macroscopic disk...
Show moreThe seeds of planetesimals that formed in the gaseous protoplanetary disk (PPD) have many barriers to overcome in their growth from millimeter to meter-sized and larger bodies. Centimeter-sized aggregates are weakly bound and self-gravity is almost non-existent so surface forces play a critical role in holding small loosely-bound rubble-piles together. Their orbital motions and effects form disk processes impart relative velocities leading to collisions so understanding the macroscopic disk environment is also necessary. To this end we analyze the dynamics of particles in Saturn's F ring as an analogue to understanding the orbital evolution of proto-planetesimals embedded in a PPD. We also study how the mechanical, material, and collisional properties affect the dynamical accretion of cm-sized bodies. The collisional outcomes can be determined by a set of definable collision parameters, and experimental constraints on these parameters will improve formation models for planetesimals. We have carried out a series of microgravity laboratory collision experiments of small aggregates to determine under what conditions collisional growth can occur for protoplanetary aggregates. We measure coefficients of restitution, sticking and fragmentation thresholds, compressive strengths, and sticking probabilities for collision velocities of 1 - 200 cm/s, then compare the results of our experiments with results from a collisional N-body code that includes adhesion between particles. We find that cm-sized aggregates are very weakly bound and require high internal cohesion to avoid fragmentation in agreement with simulations. The threshold for sticking is found to be under 10 cm/s and the fragmentation threshold near 1 m/s. Quiescent regions in the mid-plane of the disk may cultivate abnormally low relative velocities permitting sticking to occur (~1 cm/s), however, without a well-defined path to formation it is difficult to determine whether collisional accretion as a mechanism can overcome low thresholds for sticking and fragmentation. We discuss this research's implications to both the meter-barrier and planetesimal formation.
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Date Issued
2016
Identifier
CFE0006196, ucf:51103
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0006196