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The Role of CD90 in Breast Cancer Tumor ProgressionMonica Chanda (9182417) 29 July 2020 (has links)
<p>Breast cancer is the most common cancer among women, with
effective treatments if the disease stays local. However, if the tumor
metastasizes, patient outcomes are significantly reduced. Mesenchymal stem
cells (MSC) have been shown to enhance metastasis by facilitating invasion and
tumor outgrowth. MCF10A Ca1h cells, a mesenchymal-like cell line, have been
shown to promote metastasis in a murine model and enhance the survival and
proliferation of their epithelial counterpart (Ca1a) in coculture. We have
established the presence of the classic MSC markers, CD90, CD105, and CD73, on
the Ca1h cells and observe a decrease in the CD90<sup>+</sup> population in the
Ca1a and fibronectin knockdown Ca1h cells. To examine the effects of this
decreased expression, a CD90 knockdown of Ca1h cells was created using
lenti-viral transduction. A decrease in fibronectin levels was seen in the CD90
knockdowns, along with a change in morphological characteristics of the cells.
To investigate the influence of a 3D microenvironment on cell phenotype, they
were also cultured on fibronectin coated scaffolds and evaluated for CD44/CD24
expression. Lastly, the knockdowns were cocultured with the Ca1a cells in a 3D
hydrogel to assess the impact of coculture on survival and proliferation. We
found that the CD90 knockdowns take on epithelial-like characteristics and
decrease survival of Ca1a cells in coculture. These findings suggest that CD90
is necessary to maintain a mesenchymal phenotype and could be used as a target
for therapies to prevent metastasis. </p>
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Assessing Collaborative Physical Tasks via Gestural Analysis using the "MAGIC" ArchitectureEdgar Javier Rojas Munoz (9141698) 29 July 2020 (has links)
Effective collaboration in a team is a crucial skill.
When people interact together to perform physical tasks, they rely on gestures
to convey instructions. This thesis explores gestures as means to assess
physical collaborative task understanding. This research proposes a framework
to represent, compare, and assess gestures’ morphology, semantics, and
pragmatics, as opposed to traditional approaches that rely mostly on the
gestures’ physical appearance. By leveraging this framework, functionally
equivalent gestures can be identified and compared. In addition, a metric to
assess the quality of assimilation of physical instructions is computed from
gesture matchings, which acts as a proxy metric for task understanding based on
gestural analysis. The correlations between this proposed metric and three
other task understanding proxy metrics were obtained. Our framework was
evaluated through three user studies in which participants completed shared
tasks remotely: block assembly, origami, and ultrasound training. The results
indicate that the proposed metric acts as a good estimator for task
understanding. Moreover, this metric provides task understanding insights in
scenarios where other proxy metrics show inconsistencies. Thereby, the approach
presented in this research acts as a first step towards assessing task
understanding in physical collaborative scenarios through the analysis of
gestures.
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Shear Response of Rock Discontinuities: Through the Lens of GeophysicsHala El Fil (11178147) 26 July 2021 (has links)
<p>Failure along rock discontinuities can result in economic losses
as well as loss of life. It is essential to develop methods that monitor the
response of these discontinuities to shear loading to enable prediction of
failure. Laboratory experiments are performed to investigate geophysical
techniques to monitor shear failure of a pre-existing discontinuity to detect
signatures of impending failure. Previous studies have detected precursors to
shear failure in the form of maxima of transmitted waves across a discontinuity
under shear. However, those experiments focused on well-matched
discontinuities. However, in nature, rock discontinuities are not always
perfectly matched because the asperities may be weathered by chemical, physical
or mechanical processes. Further, the specific shear mechanism of mismatched
discontinuities is still poorly understood. In this thesis, the ability
to detect seismic precursors to shear failure for various discontinuity
conditions—well-matched (rough and saw-tooth), mismatched (rough), and
nonplanar (discontinuity profile with a half-cycle sine wave (HCS))—was
assessed. The investigation was carried out through a coupled geophysical and
mechanical experimental program that integrated detailed laboratory
observations at the micro- and meso-scales. Shear experiments on gypsum discontinuities were conducted
to observe changes in compressional (P) and shear (S) waves transmitted across
the discontinuity. Digital
Image Correlation (DIC) was used to quantify the vertical and horizontal
displacements along the discontinuity during shearing to relate the location
and magnitude of slip with the measured wave amplitudes. </p>
<p>Results from the experiments conducted on planar, well-matched rough
discontinuities (grit 36 sandpaper roughness) showed that seismic precursors to
failure took the form of peaks in the normalized transmitted amplitude prior to
the peak shear stress. Seismic wave transmission detected non-uniform
dilation and closure of the discontinuity at a normal stress of 1 MPa. The
results showed that large-scale roughness (presence of a HCS) could mask the
generation of precursors, as it can cause non-uniform closure/dilation along
the fracture plane at low normal stress.
</p>
<p>The experiments on idealized
saw-toothed gypsum discontinuities showed that seismic precursors to failure
appeared as maxima in the transmitted wave amplitude and conversely as minima
in the reflected amplitudes. Converted waves (S to P & P to S) were also
detected, and their amplitudes reached a maximum prior to shear failure. DIC
results showed that slip occurred first at the top of the specimen, where the
load was applied, and then progressed along the joint as the shear stress
increased. This process was consistent with the order of emergence of
precursors, i.e., precursors were first recorded near the top and later at the
center, and finally at the bottom of the specimen. </p>
<p>Direct shear
experiments conducted on specimens with a mismatched discontinuity did not show
any precursors (in the transmitted amplitude) to failure at low normal stresses
(2 MPa), while those precursors appeared at higher normal stresses (5 MPa). The
interplay between wave transmission, the degree of mismatch, and the
discontinuity’s micro-physical, -chemical and -mechanical properties was
assessed through: (1) 3D CT in-situ Xray scans to quantify the degree of
mismatch at various normal stresses; (2) micro-indentation testing, to measure
the micro-strength of the asperities; and (3) Scanning Electron Microscopy
(SEM) and Electron Xray Diffraction (EDX), to study the micro-structure and
chemical composition of the discontinuity. The X-ray results showed that
contact between asperities increased with normal stress, even when the
discontinuity was mismatched. The results indicated that: (1) at 2 MPa, the
void aperture was large, so significant shear displacement was needed to interlock
and damage the asperities; and (2) the micro-hardness of the asperities of the
mismatched discontinuity was larger than that of the well-matched discontinuity,
which points to inducing less damage for the same shear displacement. Both
mechanisms contribute to the need for larger shear displacements to the mismatched
discontinuity asperities to cause damage, which is consistent with the
inability to detect seismic precursors to failure. The experimental results
suggest that monitoring changes in transmitted wave amplitude across a
discontinuity is a promising method for predicting impending failure for well-matched
rock discontinuities. Precursor monitoring for mismatched rock discontinuities
seems only possible when there is sufficient contact between the two rock
surfaces, which occurs at large normal stresses. </p>
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Deeply-Scaled Fully Self-Aligned Trench MOSFETs in 4H-SiCMadankumar Sampath (11184465) 27 July 2021 (has links)
<p>Increasing demand for higher power density in many applications such as Hybrid Electric Vehicles (HEVs) and renewable power generation has led to great technological advances in power electronics. To meet this increasing demand, a power semiconductor device needs to have low on resistance, increased switching speeds and reduced total system cost. Silicon (Si) power devices have been used for several decades but they are fundamentally limited by material properties. Silicon carbide (SiC) as a power semiconductor material offers superior electrical and thermal properties compared to silicon, which it can replace in a large spectrum of applications. Because of a lower critical electric field, drift regions in Si power transistors need to be much thicker and more lightly doped, which in turn increases the specific onresistance Ron,sp. To combat the drift resistance component for higher blocking voltages, superjunction MOSFETs for medium voltages and Si IGBTs for high voltages are used. Since IGBTs are bipolar transistors, they exhibit much higher switching energy losses than MOSFETs. The SiC MOSFET is an excellent candidate in the medium to high voltage range, which mainly targets the HEV market.</p><p><br></p><p>Due to their low channel mobility, SiC MOSFETs have not reached the theoretical limit below 1200 V where channel resistance is dominant. Planar DMOSFETs dominate the</p><p>commercial SiC market today because of higher yield and relatively simpler fabrication process, but trench MOSFETs can be made with a smaller cell area and thus lower Ron,sp. Due to lower cell-pitch and high integration density of trench-gate devices, they offer an opportunity to reduce the size and weight of HEV power control units by replacing IGBTs with MOSFETs. The single-trench UMOSFET was first reported in 1994 by CREE and the first oxide protected trench MOSFET in 1998 by Purdue. This structure inserts a grounded p-type region below the gate trench to protect the oxide in the blocking state. In 2012, Rohm Semiconductor reported a novel double-trench UMOSFET with separate gate and</p><p>field-protection trenches. In 2017, Infineon published their new trench UMOSFET, known as Cool-SiC, with high gate oxide reliability. In this work a deeply-scaled, fully-self-aligned trench MOSFET is fabricated and characterized. The innovative process described enables a record cell-pitch of 0.5 μm per channel, equivalent to a channel density 6Å~ higher than currently available commercial UMOSFETs.</p>
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Experimental and Numerical Study of 3D Nanolithography Using Photoinitiator DepletionJinwoo Kim (16678479) 02 August 2023 (has links)
<p>Fabricating complex submicron 3D structures can be achieved by multi-photon lithography, especially two-photon lithography is commonly used to obtain precision and flexibility in printing sophisticated sub-micron 3D structures. Several disadvantages stemmed from a two-photon lithography experiment setup, including cost, the necessity of a large laboratory space to use a femtosecond laser and a high-order process. A two-step absorption is chosen instead of two-photon lithography as a primary excitation process achieving the same degree of quadratic optical non- linearity as two-photon lithography at a lower cost with a relatively compact laboratory size. The working mechanism of Two-step absorption is the following. Quadratic nonlinearity comes from radicals from excited triplet states photoinitiators. Ground states of photoinitiators get excited by the incident laser. Those excited singlet photoinitiators go through the intersystem crossing, becoming the ground triplet state of photoinitiators. There are two branches after the ground triplet states, especially for photoinitiator benzil molecules with the incident laser on. Either it becomes a radical without photons received from the incident laser or gets excited again to an excited triplet state by the incident laser. Those excited triplet-state photoinitiator molecules become radicals that occur in polymerization. However, those from the ground triplet states add linearity to polymerization. When it comes to multiple exposures, the linearity becomes problematic, especially outside the region and tails of the voxel. For example, suppose the intensity at two tails of the voxel is 1% relative to the maximum intensity at the focal point. In that case, the absorbed dose will be added up to the maximum intensity at the focal point when it comes to 100 exposures. Quadratic nonlinearity and linearity are jumbled together in the current two-step absorption process. In this work, optimization of photoinitiator concentration was conducted to reduce the linearity. Confined and high throughput 3D structure fabrications are achieved by controlling initiator depletion. Simulations are also developed with multi-physics models to compare with the empirical results.</p>
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THEORETICAL ANALYSIS OF MICROWAVE BREAKDOWN FOR MICROSCALE GAPSShivani Mahajan (16640952) 25 July 2023 (has links)
<p>Dielectric breakdown in gases is an important criterion for device reliability when designing various electronic devices such as sensors, medical plasma jets and fusion applications. As devices become smaller and more compact, microscale gap distances need to be considered and Paschen’s law, which dictates typical breakdown behavior when electron avalanche dominates, fails. The stronger electric fields for microscale gaps induce field emission, which generates additional electrons that further enhance the electric field at the cathode and the resulting secondary emission to reduce breakdown voltages below those predicted by Paschen’s law. Field emission is governed by the Fowler-Nordheim equation, which mathematically describes the quantum tunneling that occurs. Many studies have examined breakdown voltage in the Paschen’s and field emission regimes but recent theories have unified the two regimes for DC gas breakdown at microscale gaps [A. L. Garner, A. M. Loveless, J. N. Dahal, and A. Venkattraman (2020)]. However, although microwave and RF fields are used in many microelectronics systems and microplasmas, they have been less studied. This thesis derives a breakdown condition that unifies avalanche and field emission for RF fields. The derivation includes analysis of potential secondary emission representations for AC fields. The breakdown condition is then benchmarked to simulations that accounts for both avalanche and field emission for user-defined AC fields.</p>
<p>We use a modified version of XPDP1, which is a one-dimensional in space and three-dimensional in velocity (1D/3v) particle-in-cell (PIC) code that incorporates field emission. The resulting breakdown depends on several parameters, most notably gap size d, pressure p and frequency f. We determine breakdown voltages in terms of d and pd scalings for 1-10 𝜇m gap distances, 10-1000 GHz frequencies, and 180-760 Torr pressures. Additional scalings that were studied include the work function, field enhancement factor, secondary emission, and ionization coefficients. PIC demonstrated that the breakdown voltage varied linearly with gap distance up to ~4 𝜇m from DC to 10 GHz for a secondary electron emission coefficient 𝛾𝑆𝐸=0.05. For DC fields, the breakdown voltage decreases with increasing gap distance; the breakdown voltage increases with increasing frequency, approaching linearly with increasing gap distance.</p>
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Stretchable 4-Channel Neck RF Coil for 3T MRIMinseon Gim (11205321) 29 July 2021 (has links)
<p>Advancements on flexible radiofrequency
(RF) coils have been made to accommodate a variety of body sizes with great
image quality and a comfortable imaging process. RF coils are magnetic field
antennas for magnetic resonance imaging (MRI) that broadcast the RF signal to
the patient and receive the returning signal to affect the image quality. The
conventional neck RF coil is rigid and requires the patients to be in supine
position. Due to its characteristics, the patients who have difficulties to move
their neck experience an uncomfortable imaging process. The novel 4-channel
neck RF coil is made of conductive silver thread embroidered on stretchable
fabric to provide patients a more comfortable experience with lightweight and flexible
materials. A wide range of neck sizes can be covered with the stretchable materials
and great image quality can be acquired due to the RF coil positioned close to
the source. The stretchable RF coil was built as non-overlapping 4 channels in
zigzag stitch pattern and tested on a dielectric phantom, which was made to
have the permittivity and conductivity of muscle at 128 MHz. The research can
be extended to stretchable RF coils with more channels and different stitching
patterns. It also has potential to be applied on joints such as wrist and ankle
due to its flexibility to cover the curved surface. </p>
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Intermetallic Growth of Cu6Sn5 as a function of Cu crystallographic orientationZiyun Huang (11204073) 29 July 2021 (has links)
<p>The morphologies and growth behavior of Cu<sub>6</sub>Sn<sub>5</sub> intermetallic compound (IMC) formed between Sn-based solder and large-grain polycrystalline Cu substrate were systematically investigated. Hexagonal Cu<sub>6</sub>Sn<sub>5</sub> grains were observed to form at certain reflow condition, which matches well with the literature results for IMC growing on single crystal substrate. The kinetics of IMC growth was also investigated and different mechanisms were proposed for different evolution stages. It was observed that facet formation should be a growth shape rather than an equilibrium shape, and the orientation relationship between Cu and Cu<sub>6</sub>Sn<sub>5</sub> was studied using scanning electron microscope (SEM) and Electron backscatter diffraction (EBSD), and were visualized on inverse pole figure. </p>
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Two-Dimensional Suborbital Slosh ExperimentMonish Mahesh Lokhande (15343090) 25 April 2023 (has links)
<p>The aim of the project is to collect empirical data on contact line motion in vibrating tanks under zero-gravity (zero-g) conditions. This study is particularly focused on the behavior of current green propellants, which have a high contact angle compared to traditional stores like water. As a result, the non-linear contact line and angle is expected to have a significant impact on zero-g behavior. The thesis focuses on the dynamic experiment of developing an experimental payload designed to fly on Blue Origin\textquotesingle s New Shepherd suborbital flight. The data collected from this experiment will provide a benchmark case for developers of zero-g fluid dynamics simulations to compare or improve their simulation results. The results will also be useful for testing non-linear hysteresis contact line simulations.</p>
<p><br></p>
<p>The design of the experiment mainly focuses on conducting oscillatory motion in zero gravity to observe the contact line at varying speeds. Two different liquids are intended to be tested on the same payload. The liquid is to be filled so that the free surface has a height of 1 inch, and the vibration amplitude is to be 0.1 inches. The liquid chosen closely simulates the current green propellants under development or other poorly-wetting liquids. The purpose of each of the components used in the experiment is justified with respect to the given flight design constraints, along with how the constraints impacted the experiment. The experiment is designed to sustain the forces in case of hard landing during the flight and autonomous control of motion. The experiment is staged to be ready for flight on the New Shepherd, and any future works are mentioned. </p>
<p><br></p>
<p>To meet these constraints, the experimental payload is designed with a variety of components, each chosen for its ability to perform under the given conditions. The payload includes a custom-built system, which generates the oscillatory motion necessary to observe the contact line behavior. The system is designed to be compact and lightweight, yet robust enough to withstand the forces of launch and landing. In addition, the payload includes a custom-built tank designed to hold the liquids being tested. The study of contact line motion in vibrating tanks under zero-g conditions is important in understanding the behavior of liquids in space. This study will provide crucial data that will help in the development of more accurate fluid dynamic simulations for future space missions.</p>
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USER LEAVING DETECTION VIA MMWAVE IMAGINGJiawei XU (15992207) 02 October 2023 (has links)
<p> The use of smart devices such as smartphones, tablets, and laptops skyrocketed in the last decade. These devices enable ubiquitous applications for entertainment, communication, productivity, and healthcare but also introduce big concern about user privacy and data security. In addition to various authentication techniques, automatic and immediate device locking based on user leaving detection is an indispensable way to secure the devices. Current user leaving detection techniques mainly rely on acoustic ranging and do not work well in environments with multiple moving objects. In this paper, we present mmLock, a system that enables faster and more accurate user leaving detection in dynamic environments. mmLock uses a mmWave FMCW radar to capture the user’s 3D mesh and detects the leaving gesture from the 3D human mesh data with a hybrid PointNet-LSTM model. Based on explainable user point clouds, mmLock is more robust than existing gesture recognition systems which can only identify the raw signal patterns. We implement and evaluate mmLock with a commercial off-the-shelf (COTS) TI mmWave radar in multiple environments and scenarios. We train the PointNet-LSTM model out of over 1 TB mmWave signal data and achieve 100% true-positive rate in most scenarios. </p>
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