Kevin Parrish - Academia.edu (original) (raw)
Papers by Kevin Parrish
Academic Emergency Medicine, Jul 1, 1998
Objectives: 'Ib compare student performance after Multimedia ACLS Learning System (MM) education ... more Objectives: 'Ib compare student performance after Multimedia ACLS Learning System (MM) education compared with that after standard (ST) ACLS education. Methods: Final-year medical students were divided into 2 groups based on convenience scheduling and given ACLS instruction either in a standard format or with the MM course. The sizes of the small groups and the times in small-group instruction were identical. All students were evaluated with the same 50-item multiple-choice written examination, a structured evaluation immediately after the management of a mock cardiac arrest, and a second structured evaluation of the same mock arrest (videotaped) by a n instructor blinded to the education method. Students were assigned a mark from 1 to 5 in each of 4 domains: assessment, immediate priorities, continual assessment, and leadership. Results: 75 students took the MM and 38 took the ST course. The mean 5 SD mark for the multiple-choice test was 89.3 +-4.9% (MM) vs 89.3 2 4.8% (ST); the onsite mock arrest evaluation mark (20 maximum) was 14.1 2 2.5 (MM) vs 14.1 2 2.0 (ST); and the blinded mock arrest evaluation was 13.1 2 2.9 (MM) vs 14.4 2 2.9 (ST) (p = 0.024). 1/75 (MM) vs 0/38 (ST) did not successfully complete the on-site mock arrest evaluation. More students in the MM group (46% vs 25%) required multiple attempts to successfully complete the mock arrest evaluation (p c 0.02). Conclusion: In medical students with no previous ACLS training, structured access to the multimedia ACLS Learning System provides immediate educational outcomes similar to those of a standard ACLS course. Multimedia computer-interactive learning should be enhanced with a short period of hands-on practice.
Academic Emergency Medicine, 1998
Objectives: 'Ib compare student performance after Multimedia ACLS Learning System (MM) education ... more Objectives: 'Ib compare student performance after Multimedia ACLS Learning System (MM) education compared with that after standard (ST) ACLS education. Methods: Final-year medical students were divided into 2 groups based on convenience scheduling and given ACLS instruction either in a standard format or with the MM course. The sizes of the small groups and the times in small-group instruction were identical. All students were evaluated with the same 50-item multiple-choice written examination, a structured evaluation immediately after the management of a mock cardiac arrest, and a second structured evaluation of the same mock arrest (videotaped) by a n instructor blinded to the education method. Students were assigned a mark from 1 to 5 in each of 4 domains: assessment, immediate priorities, continual assessment, and leadership. Results: 75 students took the MM and 38 took the ST course. The mean 5 SD mark for the multiple-choice test was 89.3 +-4.9% (MM) vs 89.3 2 4.8% (ST); the onsite mock arrest evaluation mark (20 maximum) was 14.1 2 2.5 (MM) vs 14.1 2 2.0 (ST); and the blinded mock arrest evaluation was 13.1 2 2.9 (MM) vs 14.4 2 2.9 (ST) (p = 0.024). 1/75 (MM) vs 0/38 (ST) did not successfully complete the on-site mock arrest evaluation. More students in the MM group (46% vs 25%) required multiple attempts to successfully complete the mock arrest evaluation (p c 0.02). Conclusion: In medical students with no previous ACLS training, structured access to the multimedia ACLS Learning System provides immediate educational outcomes similar to those of a standard ACLS course. Multimedia computer-interactive learning should be enhanced with a short period of hands-on practice.
The operating temperature of energy conversion and electronic devices affects their efficiency an... more The operating temperature of energy conversion and electronic devices affects their efficiency and efficacy. In many devices, however, the reference values of the thermal properties of the materials used are no longer applicable due to processing techniques performed. This leads to challenges in thermal management and thermal engineering that demand accurate predictive tools and high fidelity measurements. The thermal conductivity of strained, nanostructured, and ultra-thin dielectrics are predicted computationally using solutions to the Boltzmann transport equation. Experimental measurements of thermal diffusivity are performed using transient grating spectroscopy. The thermal conductivities of argon, modeled using the Lennard-Jones potential, and silicon, modeled using density functional theory, are predicted under compressive and tensile strain from lattice dynamics calculations. The thermal conductivity of silicon is found to be invariant with compression, a result that is in di...
arXiv: Materials Science, 2020
Electrides, with excess anionic electrons confined in their empty space, are promising for uses i... more Electrides, with excess anionic electrons confined in their empty space, are promising for uses in catalysis, nonlinear optics and spin-electronics. However, the application of electrides is limited by their high chemical reactivity with the environmental agents. In this work, we report the discovery of a group of two-dimensional (2D) moonolayer electrides with the presence of switchable nearly free electron (NFE) states in their electronic structures. Unlike conventional electrides, which are metals with floating electrons forming the partially occupied bands close to the Fermi level, the switchable electrides are chemically much less active semiconductors holding the NFE states that are 0.3-1.5 eV above the Fermi level. According to a high throughput search, we identified 12 2D candidates that possess such low-energy NFE states. Among them, 11 2D materials can likely be exfoliated from the known layered materials. Under external forces, such as a compressive strain, these NFE stat...
Accurate measurements of the size-dependent lattice thermal conductivity (κ l) of alloy nanostruc... more Accurate measurements of the size-dependent lattice thermal conductivity (κ l) of alloy nanostructures are challenging but help to address outstanding questions on the effects of atomic disorder and surface roughness on low-frequency vibrational modes in functional materials. Here, we report sensitive κ l measurements of multiple segments of the same individual SiGe nanowires. In contrast to a previous report of ballistic thermal transport over several microns in SiGe nanowires, the obtained κ l are nearly independent of the segment length from 2 to 10 μm and the temperature between 150 and 300 K. The results are in agreement with a theoretical calculation based on the virtual crystal approximation of the vibrational modes as phonons with mean free paths suppressed by purely diffuse surface scattering. The findings inform continuing theoretical efforts for understanding the roles of different types of vibrational modes in thermal transport in disordered thermoelectric and electronic materials.
Physical Review B, 2020
Thermal transport by phonons in films with thicknesses of less than 10 nm is investigated in a so... more Thermal transport by phonons in films with thicknesses of less than 10 nm is investigated in a soft system (Lennard-Jones argon) and a stiff system (Tersoff silicon) using two-dimensional lattice dynamics calculations and the Boltzmann transport equation. This approach uses a unit cell that spans the film thickness, which removes approximations related to the finite cross-plane dimension required in typical three-dimensional-based approaches. Molecular dynamics simulations, which make no assumptions about the nature of the thermal transport, are performed to obtain finite-temperature structures for the lattice dynamics calculations and to predict thermal conductivity benchmarks. Thermal conductivity decreases with decreasing film thickness for both the two-dimensional lattice dynamics calculations and the MD simulations, until the thickness reaches four unit cells (2.1 nm) for argon and three unit cells (1.6 nm) for silicon. With a further decrease in film thickness, thermal conductivity plateaus in argon while it increases in silicon. This unexpected behavior, which we identify as a signature of phonon confinement, is a result of an increased contribution from low-frequency phonons, whose density of states increases as the film thickness decreases. Phonon mode-level analysis suggests that confinement effects emerge below thicknesses of ten unit cells (5.3 nm) for argon and six unit cells (3.2 nm) for silicon. These transition points both correspond to approximately twenty atomic layers. Thermal conductivity predictions based on the bulk (i.e., three-dimensional) phonon properties combined with a boundary scattering model do not capture the low thickness behavior. To match the two-dimensional lattice dynamics and molecular dynamics predictions for larger thicknesses, the three-dimensional lattice dynamics calculations require a finite specularity parameter that in some cases approaches unity. These findings point to the challenges associated with interpreting experimental thermal conductivity measurements of ultrathin silicon films, where surface roughness and a native oxide layer impact phonon transport.
Current Stem Cell Research & Therapy, 2019
Diabetes mellitus is an autoimmune disease which causes loss of insulin secretion producing hyper... more Diabetes mellitus is an autoimmune disease which causes loss of insulin secretion producing hyperglycemia by promoting progressive destruction of pancreatic β cells. An ideal therapeutic approach to manage diabetes mellitus is pancreatic β cells replacement. The aim of this review article was to evaluate the role of nanofibrous scaffolds and stem cells in the treatment of diabetes mellitus. Various studies have pointed out that application of electrospun biomaterials has considerably attracted researchers in the field of tissue engineering. The principles of cell therapy for diabetes have been reviewed in the first part of this article, while the usability of tissue engineering as a new therapeutic approach is discussed in the second part.
Academic Emergency Medicine, Jul 1, 1998
Objectives: 'Ib compare student performance after Multimedia ACLS Learning System (MM) education ... more Objectives: 'Ib compare student performance after Multimedia ACLS Learning System (MM) education compared with that after standard (ST) ACLS education. Methods: Final-year medical students were divided into 2 groups based on convenience scheduling and given ACLS instruction either in a standard format or with the MM course. The sizes of the small groups and the times in small-group instruction were identical. All students were evaluated with the same 50-item multiple-choice written examination, a structured evaluation immediately after the management of a mock cardiac arrest, and a second structured evaluation of the same mock arrest (videotaped) by a n instructor blinded to the education method. Students were assigned a mark from 1 to 5 in each of 4 domains: assessment, immediate priorities, continual assessment, and leadership. Results: 75 students took the MM and 38 took the ST course. The mean 5 SD mark for the multiple-choice test was 89.3 +-4.9% (MM) vs 89.3 2 4.8% (ST); the onsite mock arrest evaluation mark (20 maximum) was 14.1 2 2.5 (MM) vs 14.1 2 2.0 (ST); and the blinded mock arrest evaluation was 13.1 2 2.9 (MM) vs 14.4 2 2.9 (ST) (p = 0.024). 1/75 (MM) vs 0/38 (ST) did not successfully complete the on-site mock arrest evaluation. More students in the MM group (46% vs 25%) required multiple attempts to successfully complete the mock arrest evaluation (p c 0.02). Conclusion: In medical students with no previous ACLS training, structured access to the multimedia ACLS Learning System provides immediate educational outcomes similar to those of a standard ACLS course. Multimedia computer-interactive learning should be enhanced with a short period of hands-on practice.
Academic Emergency Medicine, 1998
Objectives: 'Ib compare student performance after Multimedia ACLS Learning System (MM) education ... more Objectives: 'Ib compare student performance after Multimedia ACLS Learning System (MM) education compared with that after standard (ST) ACLS education. Methods: Final-year medical students were divided into 2 groups based on convenience scheduling and given ACLS instruction either in a standard format or with the MM course. The sizes of the small groups and the times in small-group instruction were identical. All students were evaluated with the same 50-item multiple-choice written examination, a structured evaluation immediately after the management of a mock cardiac arrest, and a second structured evaluation of the same mock arrest (videotaped) by a n instructor blinded to the education method. Students were assigned a mark from 1 to 5 in each of 4 domains: assessment, immediate priorities, continual assessment, and leadership. Results: 75 students took the MM and 38 took the ST course. The mean 5 SD mark for the multiple-choice test was 89.3 +-4.9% (MM) vs 89.3 2 4.8% (ST); the onsite mock arrest evaluation mark (20 maximum) was 14.1 2 2.5 (MM) vs 14.1 2 2.0 (ST); and the blinded mock arrest evaluation was 13.1 2 2.9 (MM) vs 14.4 2 2.9 (ST) (p = 0.024). 1/75 (MM) vs 0/38 (ST) did not successfully complete the on-site mock arrest evaluation. More students in the MM group (46% vs 25%) required multiple attempts to successfully complete the mock arrest evaluation (p c 0.02). Conclusion: In medical students with no previous ACLS training, structured access to the multimedia ACLS Learning System provides immediate educational outcomes similar to those of a standard ACLS course. Multimedia computer-interactive learning should be enhanced with a short period of hands-on practice.
The operating temperature of energy conversion and electronic devices affects their efficiency an... more The operating temperature of energy conversion and electronic devices affects their efficiency and efficacy. In many devices, however, the reference values of the thermal properties of the materials used are no longer applicable due to processing techniques performed. This leads to challenges in thermal management and thermal engineering that demand accurate predictive tools and high fidelity measurements. The thermal conductivity of strained, nanostructured, and ultra-thin dielectrics are predicted computationally using solutions to the Boltzmann transport equation. Experimental measurements of thermal diffusivity are performed using transient grating spectroscopy. The thermal conductivities of argon, modeled using the Lennard-Jones potential, and silicon, modeled using density functional theory, are predicted under compressive and tensile strain from lattice dynamics calculations. The thermal conductivity of silicon is found to be invariant with compression, a result that is in di...
arXiv: Materials Science, 2020
Electrides, with excess anionic electrons confined in their empty space, are promising for uses i... more Electrides, with excess anionic electrons confined in their empty space, are promising for uses in catalysis, nonlinear optics and spin-electronics. However, the application of electrides is limited by their high chemical reactivity with the environmental agents. In this work, we report the discovery of a group of two-dimensional (2D) moonolayer electrides with the presence of switchable nearly free electron (NFE) states in their electronic structures. Unlike conventional electrides, which are metals with floating electrons forming the partially occupied bands close to the Fermi level, the switchable electrides are chemically much less active semiconductors holding the NFE states that are 0.3-1.5 eV above the Fermi level. According to a high throughput search, we identified 12 2D candidates that possess such low-energy NFE states. Among them, 11 2D materials can likely be exfoliated from the known layered materials. Under external forces, such as a compressive strain, these NFE stat...
Accurate measurements of the size-dependent lattice thermal conductivity (κ l) of alloy nanostruc... more Accurate measurements of the size-dependent lattice thermal conductivity (κ l) of alloy nanostructures are challenging but help to address outstanding questions on the effects of atomic disorder and surface roughness on low-frequency vibrational modes in functional materials. Here, we report sensitive κ l measurements of multiple segments of the same individual SiGe nanowires. In contrast to a previous report of ballistic thermal transport over several microns in SiGe nanowires, the obtained κ l are nearly independent of the segment length from 2 to 10 μm and the temperature between 150 and 300 K. The results are in agreement with a theoretical calculation based on the virtual crystal approximation of the vibrational modes as phonons with mean free paths suppressed by purely diffuse surface scattering. The findings inform continuing theoretical efforts for understanding the roles of different types of vibrational modes in thermal transport in disordered thermoelectric and electronic materials.
Physical Review B, 2020
Thermal transport by phonons in films with thicknesses of less than 10 nm is investigated in a so... more Thermal transport by phonons in films with thicknesses of less than 10 nm is investigated in a soft system (Lennard-Jones argon) and a stiff system (Tersoff silicon) using two-dimensional lattice dynamics calculations and the Boltzmann transport equation. This approach uses a unit cell that spans the film thickness, which removes approximations related to the finite cross-plane dimension required in typical three-dimensional-based approaches. Molecular dynamics simulations, which make no assumptions about the nature of the thermal transport, are performed to obtain finite-temperature structures for the lattice dynamics calculations and to predict thermal conductivity benchmarks. Thermal conductivity decreases with decreasing film thickness for both the two-dimensional lattice dynamics calculations and the MD simulations, until the thickness reaches four unit cells (2.1 nm) for argon and three unit cells (1.6 nm) for silicon. With a further decrease in film thickness, thermal conductivity plateaus in argon while it increases in silicon. This unexpected behavior, which we identify as a signature of phonon confinement, is a result of an increased contribution from low-frequency phonons, whose density of states increases as the film thickness decreases. Phonon mode-level analysis suggests that confinement effects emerge below thicknesses of ten unit cells (5.3 nm) for argon and six unit cells (3.2 nm) for silicon. These transition points both correspond to approximately twenty atomic layers. Thermal conductivity predictions based on the bulk (i.e., three-dimensional) phonon properties combined with a boundary scattering model do not capture the low thickness behavior. To match the two-dimensional lattice dynamics and molecular dynamics predictions for larger thicknesses, the three-dimensional lattice dynamics calculations require a finite specularity parameter that in some cases approaches unity. These findings point to the challenges associated with interpreting experimental thermal conductivity measurements of ultrathin silicon films, where surface roughness and a native oxide layer impact phonon transport.
Current Stem Cell Research & Therapy, 2019
Diabetes mellitus is an autoimmune disease which causes loss of insulin secretion producing hyper... more Diabetes mellitus is an autoimmune disease which causes loss of insulin secretion producing hyperglycemia by promoting progressive destruction of pancreatic β cells. An ideal therapeutic approach to manage diabetes mellitus is pancreatic β cells replacement. The aim of this review article was to evaluate the role of nanofibrous scaffolds and stem cells in the treatment of diabetes mellitus. Various studies have pointed out that application of electrospun biomaterials has considerably attracted researchers in the field of tissue engineering. The principles of cell therapy for diabetes have been reviewed in the first part of this article, while the usability of tissue engineering as a new therapeutic approach is discussed in the second part.