Thin Film Encapsulation of Radio Frequency (RF) Microelectromechanical Systems (MEMS) Switches

Microelectromechanical systems (MEMS) radio frequency (RF) switches have been shown to have excellent electrical performance over a wide range of frequencies. However, cost-effective packaging techniques for MEMS switches do not currently exist. This thesis involves the design of RF-optimized encapsulations consisting of dielectric and metal layers, and the creation of a novel thin film encapsulation process to fabricate the encapsulations. The RF performance of several encapsulation designs are evaluated with an analytical model, full wave electromagnetic simulation, and laboratory testing. Performance degradation due to parasitic and reflection losses due to the package is considered, and RF feed-throughs of the transmission line into and out of the package are designed and assessed. Ten different encapsulation designs were created and their RF performance was characterized in terms of insertion loss, return loss, and isolation. A switch without an encapsulation and a switch with a dielectric encapsulation were fabricated and tested by the Air Force Research Laboratory (AFRL), and the test data was used to verify the data from analytical modeling and electromagnetic simulation performed in this work. All results were used to design an optimized encapsulation. An RF MEMS switch with this encapsulation was shown to have an overall insertion loss of less than -0.15 dB at 20 GHz compared to an unencapsulated switch insertion loss of about -0.1 dB. The isolation of the switch was slightly improved with the encapsulation. The fabrication process proposed to manufacture these encapsulations uses a low temperature solder as the metal encapsulation layer. As the final step in the fabrication, the solder is brought to melting temperature and reflowed over the etch holes to form a hermetic encapsulation

G-Wires: Self-Assembly of a Telomeric Oligonucleotide, d(GGGGTTGGGG), into Large Superstructures

The telomeric DNA oligonucleotide 5’-G4T~G4-3’ (Tet 1.5) spontaneously assembles into large superstructures we have termed G-wires. G-wires can be resolved by gel electrophoresis as a ladder pattern. The self-association of Tet 1.5 is noncovalent and exhibits characteristics of G4-DNA, a parallel fourstranded structure stabilized by guanine tetrads. Formation of G-wires is dependent upon the presence of Na+ and/or K+, and once formed, G-wires are resistant to denaturation. The results described here extend our understanding of the structural potential of G-rich nucleic acids and may provide insight into the possible roles of G-rich sequences and the novel structures they can form in biological systems

Electrophysiological Biomarkers in Genetic Epilepsies.

Precision treatments for epilepsy targeting the underlying genetic diagnoses are becoming a reality. Historically, the goal of epilepsy treatments was to reduce seizure frequency. In the era of precision medicine, however, outcomes such as prevention of epilepsy progression or even improvements in cognitive functions are both aspirational targets for any intervention. Developing methods, both in clinical trial design and in novel endpoints, will be necessary for measuring, not only seizures, but also the other neurodevelopmental outcomes that are predicted to be targeted by precision treatments. Biomarkers that quantitatively measure disease progression or network level changes are needed to allow for unbiased measurements of the effects of any gene-level treatments. Here, we discuss some of the promising electrophysiological biomarkers that may be of use in clinical trials of precision therapies, as well as the difficulties in implementing them

Virtual Distance Estimation in a CAVE

Past studies have shown consistent underestimation of distances in virtual reality, though the exact causes remain unclear. Many virtual distance cues have been investigated, but past work has failed to account for the possible addition of cues from the physical environment. We describe two studies that assess users' performance and strategies when judging horizontal and vertical distances in a CAVE. Results indicate that users attempt to leverage cues from the physical environment when available and, if allowed, use a locomotion interface to move the virtual viewpoint to facilitate this

An Assessment of the Interaction between High Tunnels and Crop Insurance for Specialty Crop Producers

Protective covers, such as high tunnels, are being used by specialty crop producers to enhance production quality and yields, expand or growing seasons, and protect crops from some extreme elements. While growing in popularity, one barrier to larger utilization includes the uncertainty regarding their practices and benefits. This paper recognizes that high tunnels can be used as a form of risk management and examines the relationship with crop insurance in order to better define optimal risk management strategies.high tunnels, specialty crop insurance, risk management, Production Economics,

Magma flow inferred from AMS fabrics in a layered mafic sill, Insizwa, South Africa

The Insizwa sill, is a 25-km-diameter, >1000-m-thick layered mafic intrusion, part of the Karoo Igneous Province in South Africa. The peridotitic and gabbronoritic rocks are undeformed and mineral fabrics demonstrably result from magma flow. A horizontal, centimeter-scale model layering is visible in numerous outcrops. Plagioclase crystals are both tabular and elongated. Their preferred orientation, parallel to the layering, forms a foliation and a NW–SE lineation, respectively interpreted as the magma flow plane and flow direction. Throughout the 78 stations of this study (699 specimens), magnetic susceptibilities (K[subscript m]) range from 750 to 10,000×10[superscript (−6)] SI. The magnetic anisotropy (P[subscript j]) ranges from 1.03 to 1.08. Magnetic ellipsoids are both prolate and oblate (average T[subscript j]≈0). Anisotropy of magnetic susceptibility (AMS) fabrics are dominated by multidomain to pseudo-single domain magnetite. High-field magnetic experiments indicate that the paramagnetic contribution from the mafic silicates is less than 50 percentage for low susceptibility rock types. The anisotropy results from magnetite grain shape solely as shown by no significant increase in P[subscript j] with increasing K[subscript m]. The magnetic lineation (305°, 05°) is consistent throughout the sill at various scales and coincides with the mineral lineation in average. In contrast, the magnetic foliation (125° NE 10°) is generally perpendicular to the mineral foliation and to the layering. Several explanations for this odd configuration are discussed. The variations of magnetic parameters across the layering and field observations point to a multiple injection. The magnetic lineation is consistent with the presence of a single feeder dike situated to the SE of the sill

Virtual Distance Estimation in a CAVE

Past studies have shown consistent underestimation of distances in virtual reality, though the exact causes remain unclear. Many virtual distance cues have been investigated, but past work has failed to account for the possible addition of cues from the physical environment. We describe two studies that assess users’ performance and strategies when judging horizontal and vertical distances in a CAVE. Results indicate that users attempt to leverage cues from the physical environment when available and, if allowed, use a locomotion interface to move the virtual viewpoint to facilitate this.FUI in the framework of the Callisto projec

White Light Flare Continuum Observations with ULTRACAM

We present sub-second, continuous-coverage photometry of three flares on the dM3.5e star, EQ Peg A, using custom continuum filters with WHT/ULTRACAM. These data provide a new view of flare continuum emission, with each flare exhibiting a very distinct light curve morphology. The spectral shape of flare emission for the two large-amplitude flares is compared with synthetic ULTRACAM measurements taken from the spectra during the large 'megaflare' event on a similar type flare star. The white light shape during the impulsive phase of the EQ Peg flares is consistent with the range of colors derived from the megaflare continuum, which is known to contain a Hydrogen recombination component and compact, blackbody-like components. Tentative evidence in the ULTRACAM photometry is found for an anti-correlation between the emission of these components.Comment: 8 pages, 3 figures. Proceedings of the 16th Workshop on Cool Stars, Stellar Systems, and the Sun (PASP conference series, in press

Mutation of {\tau}-exceptional pairs and sequences

We introduce a notion of mutation for $\tau$-exceptional sequences of modules over arbitrary finite dimensional algebras. For hereditary algebras, we show that this coincides with the classical mutation of exceptional sequences. For rank two algebras, we show that mutation of $\tau$-exceptional sequences is transitive if and only if mutation of support $\tau$-tilting modules in the sense of Adachi-Iyama-Reiten is transitive.Comment: 42 page