Filtering by
- Language: English
Five immunocompetent C57BL/6-cBrd/cBrd/Cr (albino C57BL/6) mice were injected with GL261-luc2 cells, a cell line sharing characteristics of human glioblastoma multiforme (GBM). The mice were imaged using magnetic resonance (MR) at five separate time points to characterize growth and development of the tumor. After 25 days, the final tumor volumes of the mice varied from 12 mm3 to 62 mm3, even though mice were inoculated from the same tumor cell line under carefully controlled conditions. We generated hypotheses to explore large variances in final tumor size and tested them with our simple reaction-diffusion model in both a 3-dimensional (3D) finite difference method and a 2-dimensional (2D) level set method. The parameters obtained from a best-fit procedure, designed to yield simulated tumors as close as possible to the observed ones, vary by an order of magnitude between the three mice analyzed in detail. These differences may reflect morphological and biological variability in tumor growth, as well as errors in the mathematical model, perhaps from an oversimplification of the tumor dynamics or nonidentifiability of parameters. Our results generate parameters that match other experimental in vitro and in vivo measurements. Additionally, we calculate wave speed, which matches with other rat and human measurements.
This paper discusses the theoretical approximation and attempted measurement of the quantum <br/>force produced by material interactions though the use of a tuning fork-based atomic force microscopy <br/>device. This device was built and orientated specifically for the measurement of the Casimir force as a <br/>function of separation distance using a piezo actuator for approaching and a micro tuning fork for the <br/>force measurement. This project proceeds with an experimental measurement of the ambient Casmir force <br/>through the use of a tuning fork-based AFM to determine its viability in measuring the magnitude of the <br/>force interaction between an interface material and the tuning fork probe. The ambient measurements <br/>taken during the device’s development displayed results consistent with theoretical approximations, while<br/>demonstrating the capability to perform high-precision force measurements. The experimental results<br/>concluded in a successful development of a device which has the potential to measure forces of <br/>magnitude 10−6 to 10−9 at nanometric gaps. To conclude, a path to material analysis using an approach <br/>stage, alternative methods of testing, and potential future experiments are speculated upon.
Tunable Near-Field Radiative Heat Transfer Exceeding Blackbody Limit with Vanadium Dioxide Thin Film
This paper investigates near-field thermal radiation as the primary source of heat transfer between two parallel surfaces. This radiation takes place extremely close to the heated surfaces in study so the experimental set-up to be used will be done at the nanometer scale. The primary theory being investigated is that near-field radiation generates greater heat flux that conventional radiation governed by Planck’s law with maximum for blackbodies. Working with a phase shift material such as VO2 enables a switch-like effect to occur where the total amount of heat flux fluctuates as VO2 transitions from a metal to an insulator. In this paper, the theoretical heat flux and near-field radiation effect are modeled for a set-up of VO2 and SiO2 layers separated by different vacuum gaps. In addition, a physical experimental set-up is validated for future near-field radiation experiments.
People generally struggle with making good decisions for their well-being (Hershfield, 2019; Hershfield & Bartels, 2018). One reason for this might be that people struggle with connecting to their future selves. Prior research suggests that future self-connectedness predicts better decisions. This study examined if feeling more positive or negative helps people connect more to their future self and if this, in turn, helps people make better decisions. Participants read a scenario in which they are presented with two decisions, one having a short-term benefit/long-term cost and the other having a short-term cost/long-term benefit. Either neutral affect framing, positive affect framing, or negative affect framing was emphasized in the scenario depending on the condition. Our study did not find that positive affect framing and negative affect framing enhanced future self-connectedness. Neither did we find that positive affect framing and negative affect framing influenced decision-making.
The Beck Depression Inventory II (BDI-II) and the Patient Health Questionnaire 9 (PHQ-9) are highly valid depressive testing tools used to measure the symptom profile of depression globally and in South Asia, respectively (Steer et al., 1998; Kroenke et al, 2001). Even though the South Asian population comprises only 23% of the world’s population, it represents one-fifth of the world’s mental health disorders (Ogbo et al., 2018). Although this population is highly affected by mental disorders, there is a lack of culturally relevant research on specific subsections of the South Asian population.
As such, the goal of this study is to investigate the differences in the symptom profile of depression in native and immigrant South Asian populations. We investigated the role of collective self-esteem and perceived discrimination on mental health.
For the purpose of this study, participants were asked a series of questions about their depressive symptoms, self-esteem and perceived discrimination using various depressive screening measures, a self-esteem scale, and a perceived discrimination scale.
We found that immigrants demonstrated higher depressive symptoms than Native South Asians as immigration was viewed as a stressor. First-generation and second-generation South Asian immigrants identified equally with somatic and psychological symptoms. These symptoms were positively correlated with perceived discrimination, and collective self-esteem was shown to increase the likelihood of these symptoms.
This being said, the results from this study may be generalized only to South Asian immigrants who come from highly educated and high-income households. Since seeking professional help and being aware of one’s mental health is vital for wellbeing, the results from this study may spark the interest in an open communication about mental health within the South Asian immigrant community as well as aid in the restructuring of a highly reliable and valid measurement to be specific to a culture.
In this thesis, aluminum metasurface structures are proposed based on colloidal lithography method. High Frequency Structure Simulator is used to numerically study optical properties and design the aluminum metasurfaces with selective absorption. Simulation results show that proposed aluminum metasurface structure on aluminum oxide thin film and aluminum substrate has a major reflectance dip, whose wavelength is tunable within the near-infrared and visible spectrum with metasurface size. As the metasurface is opaque due to aluminum film, it indicates strong wavelength-selective optical absorption, which is due to the magnetic resonance between the top metasurface and bottom Al film within the aluminum oxide layer.
The proposed sample is fabricated based on colloidal lithography method. Monolayer polystyrene particles of 500 nm are successfully prepared and transferred onto silicon substrate. Scanning electron microscope is used to check the surface topography. Aluminum thin film with 20-nm or 50-nm thickness is then deposited on the sample. After monolayer particles are removed, optical properties of samples are measured by micro-scale optical reflectance and transmittance microscope. Measured and simulated reflectance of these samples do not have frequency selective properties and is not sensitive to defects. The next step is to fabricate the Al metasurface on Al_2 O_3 and Al films to experimentally demonstrate the selective absorption predicted from the numerical simulation.
