justin shaw - Academia.edu (original) (raw)

Papers by justin shaw

Justin is pursuing a major in biomedical sciences and a minor in music. He has worked in a molecu... more Justin is pursuing a major in biomedical sciences and a minor in music. He has worked in a molecular microbiology lab focusing on the intraerythrocytic life cycle of the malaria parasite Plasmodium falciparum. He is currently in the process of completing an undergraduate thesis involving the specific inhibitory effects of a compound with novel mechanism of action on P. falciparum. In addition to his research, Justin is also the Lead Tutor for the Student Academic Resource Center here at UCF tutoring Statistical Methods I. Justin also enjoys playing the saxophone with one of UCF’s many bands throughout the year. Upon graduation, Justin hopes to attend medical school (M.D. or M.D./Ph.D.) and potentially complete a graduate degree simultaneously. He hopes to one day become a physician-scientist and continue infectious disease research as well as teaching.https://stars.library.ucf.edu/ramp_gallery/1098/thumbnail.jp

We quantify the presence of spin-mixed states in ferromagnetic 3d transition metals by precise me... more We quantify the presence of spin-mixed states in ferromagnetic 3d transition metals by precise measurement of the orbital moment. While central to phenomena such as Elliot-Yafet scattering, quantification of the spin-mixing parameter has hitherto been confined to theoretical calculations. In this talk we will demonstrate that this information is also available by experimental means. We focus on a series of Co90Fe10/Ni multilayers and a Ni80Fe20 permalloy thin film. Precise measurement of the orbital to spin moment ratio µL/µS via ferromagnetic resonance spectroscopy (FMR) and x-ray magnetic circular dichroism (XMCD) show a measurable difference. By accounting for all known experimental artifacts that can give rise to such a discrepancy, we are left to conclude that another factor is giving rise to this effect....

Skyrmions have received significant attention over the last years mostly motivated by their poten... more Skyrmions have received significant attention over the last years mostly motivated by their potential for future non-volatile memories, where the individual bits are represented by skyrmions The Dzyaloshinskii-Moriya Interaction (DMI) stabilizes skyrmions and determines their chirality. Here, we demonstrate, that the DMI can be increased by approximately 20% using by He+ ion irradiation1. This underlines the importance of interface roughness and intermixing for the DMI and provides the opportunity for local modification of the DMI. We prepared a Ta(3 nm)/Co20Fe60B20(1.9 nm)/Pt(3.5 nm)/MgO sample, which was diced in multiple coupons for irradiation with 40 keV He+ ions with a fluence up to 1016 ions/cm2. We measured the spin-wave frequencies for both field polarities in the Damon-Eshbach geometry post i...

Antisymmetric exchange interactions are used to stabilize magnetic textures and lead to non-recip... more Antisymmetric exchange interactions are used to stabilize magnetic textures and lead to non-reciprocal spin-wave propagation [1-2]. As a result, left and right propagating waves at the same energy have different wavelengths. Thus, interference between counter-propagating spin waves does not lead to standing waves; instead, confined modes have a time-dependent phase, i.e., their phase is modulated at a rate determined by the Dzyaloshinskii–Moriya interactions (DMI) [3]. We report on a Brillouin light scattering (BLS) study of confined spin waves in Co/Pt nanowires with strong DMI, whose widths range from 100 to 400 nm [4]. Two different scattering geometries were used: a transverse geometry where the incident light is perpendicular to the nanowire, as illustrated in Fig. 1(a), and a longitudinal geometry, where the incident light is parallel to the nanowire. Fig. 1(b) shows a SEM image of a nanowire array. Fig. 2(a-d) show sample BLS spectra for both scattering geometries. ...

Magnetic materials with perpendicular magnetic anisotropy (PMA) and low Gilbert damping (a) hold ... more Magnetic materials with perpendicular magnetic anisotropy (PMA) and low Gilbert damping (a) hold great promise towards faster and smaller memory and logic devices. Ferrimagnetic rare earth iron garnets with PMA have recently attracted a great deal of attention for spintronic applications. However, a major drawback for most rare earth iron garnets is their large Gilbert damping. Bi-substituted yttrium iron garnet (BiYIG) has been shown to have both PMA and low damping,[1] and spin-orbit torque-driven domain wall velocities of 4.5 km/s [2] have been observed in BiYIG/Pt. In this work we report the growth, magnetic and spintronic transport properties of single layers and heterostructures consisting of PMA BiYIG and thulium iron garnet (TmIG) grown epitaxially on substituted Gd3Ga5O12 (GSGG, SGGG) and Nd3Ga5O12</su...

Case Reports in Dentistry, Mar 29, 2022

Malignancies of salivary gland origin are rare in children. Mucoepidermoid carcinoma (MEC) is the... more Malignancies of salivary gland origin are rare in children. Mucoepidermoid carcinoma (MEC) is the most common histologic type of salivary gland neoplasm in pediatrics. We report a rare case of parotid MEC in a 20-month-old female patient. The tumor was composed of nests of epidermoid cells with nuclei appearing vesicular, pleomorphic, and hyperchromatic with an admixture of mucous cells and cystic spaces within a prominent connective tissue stroma. Immunohistochemically, the epidermoid cells showed cytokeratin 7 and P63 positivity, and mucous cells were positive for mucicarmine. Molecularly, this case was positive for MAML2 rearrangement by FISH. To our knowledge, this is one of the youngest cases of MEC of the parotid gland reported in the English literature.

Physical Review Applied, 2021

We report on the magnetic damping properties of polycrystalline Fe-V alloy thin films that are de... more We report on the magnetic damping properties of polycrystalline Fe-V alloy thin films that are deposited at room temperature. By varying the concentration of V in the alloy, the saturation magnetization can be adjusted from that of Fe to near zero. We show that exceptionally low values of the damping parameter can be maintained over the majority of this range, with a minimum damping at approximately 15%-20% V concentration. Such a minimum is qualitatively reproduced with ab initio calculations of the damping parameter, although at a concentration closer to 10% V. The measured intrinsic damping has a minimum value of (1.53 ± 0.08) × 10 −3 , which is approximately a factor of 3 higher than our calculated value of 0.48 × 10 −3. From first-principles theory, we outline the factors that are mainly responsible for the trend of the damping parameter in these alloys. In particular, the band structure and resulting damping mechanism is shown to change at V concentrations greater than approximately 35% V content.

Bulletin of the American Physical Society, Mar 16, 2016

Identity Technologies: Constructing the Self Online and Between Humanities and the Digital discus... more Identity Technologies: Constructing the Self Online and Between Humanities and the Digital discuss a central issue in defining the "digital humanities": to what extent are traditional humanistic concerns – pain, suffering, freedom, pleasure, happiness – taken into consideration in our increasingly abstract engagement with digital technologies? For some, this is a serious ethical issue that will always require the insights of the traditional humanities, while for others the "digital" needs to break free from antiquity. Along these lines, these texts diverge in tone and content: Identity Technologies leaves an impression of reluctant yet cautious optimism, while Between Humanities and the Digital is anchored in the "digital" world, focusing on digital success stories and calling for investment in digital infrastructure.

Publication in the conference proceedings of EUSIPCO, Aalborg, Denmark, 2010

Turbulence encounters continue to be one of the largest sources of personal injury in both commer... more Turbulence encounters continue to be one of the largest sources of personal injury in both commercial and general aviation. A significant percentage of these encounters occur without

Falling Men” in 9/11 American Fiction Gender critics such as Judith Butler and Michael Kimmel arg... more Falling Men” in 9/11 American Fiction Gender critics such as Judith Butler and Michael Kimmel argue that post-9/11 American culture has embraced a traditional gender binary that positions men as the dominant protectors of women, children, and the nation as a whole, exemplified by the widespread veneration of heroic firefighters, soldiers, and the civilians of flight 93 in the media (Kimmel 249). This regression reinforces hegemonic masculinity in American culture, which R.W. Connell defines as “the pattern of practice (i.e., things done, not just a set of role expectations or an identity) that allow[s] men’s dominance over women to continue” (Connell and Messerschmidt 832). Christine Beasley has “demassified” hegemonic masculinity by dividing it into two categories: sub-hegemonic masculinity, which refers to traditional modes of dominant masculinity that emphasize brawn and physical aggression, and supra-hegemonic masculinity, which designates the increasingly sublimated practices o...

The GFMosaic algorithm combines information from more than one Doppler radar to provide an improv... more The GFMosaic algorithm combines information from more than one Doppler radar to provide an improved gust front detection capability at large TRACONs covered by multiple Terminal Doppler Weather Radars (TDWR). Algorithm development and testing is presently taking place at the Dallas/Ft. Worth International Airport (DFW), where the ability to detect gust fronts in the vicinity of the airport is made more difficult because of the location of the DFW TDWR. Radar velocity signatures indicative of gust fronts often degrade or vanish due to Doppler blindness when a gust front becomes radially aligned with the radar. This problem is common at DFW since the DFW TDWR is located northeast of the airport and the most common orientation of cold fronts and thunderstorm outflow boundaries is northeast-to-southwest (Figure 1). The GFMosaic algorithm is expected to alleviate the gust front detection problem caused by radial alignment at DFW as well as provide a more robust detection capability at al...

2005 International Conference on MEMS,NANO and Smart Systems

We have been applying in situ and ex situ spin-wave Brillouin Light Scattering (BLS) techniques t... more We have been applying in situ and ex situ spin-wave Brillouin Light Scattering (BLS) techniques to spinwave structures we are growing by Molecular Beam Epitaxy (MBE). The sensitivity of our BLS technique is illustrated by our ability to measure spinwave excitations for samples as thin as 1 monolayer of Co buried by as much as 20 nanometers of Au. This talk will describe the use of in situ and ex situ BLS in combination with appropriate structural probes to determine the origin of several interesting and useful physical phenomena in spintronics structures.

PLOS ONE, 2019

We present a method for identifying features (time periods of interest) in data sets consisting o... more We present a method for identifying features (time periods of interest) in data sets consisting of time-indexed model output. The method is used as a diagnostic to quickly focus the attention on a subset of the data before further analysis methods are applied. Mathematically, the infinity norm errors of empirical orthogonal function (EOF) reconstructions are calculated for each time output. The result is an EOF reconstruction error map which clearly identifies features as changes in the error structure over time. The ubiquity of EOF-type methods in a wide range of disciplines reduces barriers to comprehension and implementation of the method. We apply the error map method to three different Computational Fluid Dynamics (CFD) data sets as examples: the development of a spontaneous instability in a large amplitude internal solitary wave, an internal wave interacting with a density profile change, and the collision of two waves of different vertical mode. In all cases the EOF error map method identifies relevant features which are worthy of further study.

Physical Review B, 2018

We show that very low values of the magnetic damping parameter can be achieved in sputter deposit... more We show that very low values of the magnetic damping parameter can be achieved in sputter deposited poly-crystalline films of Co 2 MnGe annealed at relatively low temperatures ranging from 240 °C to 400 °C. Damping values as low as 0.0014 are obtained with an intrinsic value of 0.0010 after spin-pumping contributions are considered. Of importance to most applications is the low value of inhomogeneous linewidth that yields measured linewidths of 1.8 mT and 5.1 mT at 10 GHz and 40 GHz, respectively. The damping parameter monotonically decreases as the B2 order of the films increases. This trend is reproduced and explained by ab initio calculations of the electronic structure and damping parameter. Here, the damping parameter is calculated as the structure evolves from A2 to B2 to L2 1 orders. The largest decrease in the damping parameter occurs during the A2 to B2 transition as the half-metallic phase becomes established.

Nature communications, Oct 13, 2017

The spin-orbit interaction enables interconversion between a charge current and a spin current. I... more The spin-orbit interaction enables interconversion between a charge current and a spin current. It is usually believed that in a nonmagnetic metal (NM) or at a NM/ferromagnetic metal (FM) bilayer interface, the symmetry of spin-orbit effects requires that the spin current, charge current, and spin orientation are all orthogonal to each other. Here we demonstrate the presence of spin-orbit effects near the NM/FM interface that exhibit a very different symmetry, hereafter referred to as spin-rotation symmetry, from the conventional spin Hall effect while the spin polarization is rotating about the magnetization. These results imply that a perpendicularly polarized spin current can be generated with an in-plane charge current simply by use of a FM/NM bilayer with magnetization collinear to the charge current. The ability to generate a spin current with arbitrary polarization using typical magnetic materials will benefit the development of magnetic memories.Converting charge to spin cur...

Journal of Applied Physics, 2015

We determined the spin-transport properties of Pd and Pt thin films by measuring the increase in ... more We determined the spin-transport properties of Pd and Pt thin films by measuring the increase in ferromagnetic resonance damping due to spin-pumping in ferromagnetic (FM)-nonferromagnetic metal (NM) multilayers with varying NM thicknesses. The increase in damping with NM thickness depends strongly on both the spin-and charge-transport properties of the NM, as modeled by diffusion equations that include both momentum-and spin-scattering parameters. We use the analytical solution to the spin-diffusion equations to obtain spin-diffusion lengths for Pt and Pd. By measuring the dependence of conductivity on NM thickness, we correlate the charge-and spin-transport parameters, and validate the applicability of various models for momentum-scattering and spin-scattering rates in these systems: constant, inverse-proportional (Dyakanov-Perel), and linearproportional (Elliot-Yafet). We confirm previous reports that the spin-scattering time appears to be shorter than the momentum scattering time in Pt, and the Dyakanov-Perel-like model is the best fit to the data.