Supergravity duals of gauge theories from F(4) gauged supergravity in six dimensions

We construct supergravity solutions dual to twisted field theories that are the worldvolume theories of D4-branes wrapped on 2, 3-cycles, and NS-fivebranes on 3-cycles. We first obtain the solutions for the Romans' six-dimensional gauged supergravity theories and then up-lift them to ten dimensions. In particular, we find solutions for field configurations with either non-Abelian fields or B-fields being excited. One of these solutions, in the massless case, is up-lifted to the massless type IIA string theory. This is the first example of such a kind. The cases studied provide new examples of the AdS/CFT duality involving twisted field theories.Comment: 26 pages, 3 figures, minor changes and references added to match the published versio

Student Loans and their effect on Parental Views of Education Financing

Using the 2012 wave National Longitudinal Survey of Youth 1979, this study examines the effect that parents\u27 student debt have on their decision to use tax advantage education vehicles to save for their children\u27s college. We also examine parental decisions on obtaining student loans on behalf of their children. The results show that parents who report having student loans are 61% less likely than those that report no student loan debt to use tax-advantaged education saving vehicles. However, we find no difference in the effect of having student loans on the decision to obtain debt to fund their children\u27s college education

Assessment of Outphasing Power Amplifiers and Their MMIC Implementations

Power amplifier (PA) applications consistently require increased performance for bandwidth, power, and efficiency. Modern communication and telemetry systems are required to operate across multiple bands that can span octaves while scaling down unit power amplifier cells to fit on the back-end of phased array systems. Phased array implementation scales branch complexity for both signal generation and linearization. This creates problems with conventional approaches for back-off efficiency enhancement techniques as well as increasing the importance of linearity optimization. This reduces the complexity of the digital pre-distortion (DPD) required to operate the system while maintaining high average efficiency for large peak to average power ratio (PAPR) signals. This thesis presents advanced outphasing PA architectures. Each of the architectures answers a different design challenge for modern communication and telemetry systems. Analog signal separation reduces the need for a digital signal split removing cost, size, weight, and power (C-SWaP). Improved modeling and understanding of the design of the inphasing splitter allows for optimization of linearity and efficiency. This work looks at utilizing novel power combining implementations with reconfigurable matching networks to operate outphasing PA&rsquo;s across multiple bands spanning an octave allowing for functional flexibility andreduced system complexity. The thesis works on two distinct outphasing implementations: the RF-input outphasing power amplifier (RFIO PA) and the dual-input reconfigurable outphasing power amplifier (DIRO PA). The designs presented in this work are as follows: &bull; Hybrid X-band RFIO PA utilizing a previously designed dual-input X-band outphasing monolithic microwave integrated circuit (MMIC) in an unreleased Qorvo GaN 150 nm process &bull; Hybrid X-band RFIO PA utilizing three different non-linear elements (PIN diode, diode-connected transistor, and mesa resistor) in the signal splitter design to optimize for linearity and efficiency in conjunction with a custom designed dual-input outphasing PA MMIC in Qorvo 150 nm GaN es process &bull; MMIC RFIO PA utilizing diode-connected transistors for integrated signal splitter design in Qorvo 150 nm GaN es process &bull; MMIC 6-12 GHz reconfigurable outphasing combiner with a switchable shunt line to control reactive loading in Qorvo&rsquo;s GaAs 250 nm process &bull; MMIC DIRO PA which is reconfigurable from 18-38 GHz with &gt;2 GHz of instantaneous bandwidth in the WIN semiconductor PIH-110 process</p

Scalable production of graphene inks via wet-jet milling exfoliation for screen-printed micro-supercapacitors

The miniaturization of energy storage units is pivotal for the development of next-generation portable electronic devices. Micro-supercapacitors (MSCs) hold a great potential to work as on-chip micro-power sources and energy storage units complementing batteries and energy harvester systems. The scalable production of supercapacitor materials with cost-effective and high-throughput processing methods is crucial for the widespread application of MSCs. Here, we report wet-jet milling exfoliation of graphite to scale-up the production of graphene as supercapacitor material. The formulation of aqueous/alcohol-based graphene inks allows metal-free, flexible MSCs to be screen-printed. These MSCs exhibit areal capacitance (Careal) values up to 1.324 mF cm-2 (5.296 mF cm-2 for a single electrode), corresponding to an outstanding volumetric capacitance (Cvol) of 0.490 F cm-3 (1.961 F cm-3 for a single electrode). The screen-printed MSCs can operate up to power density above 20 mW cm-2 at energy density of 0.064 uWh cm-2. The devices exhibit excellent cycling stability over charge-discharge cycling (10000 cycles), bending cycling (100 cycles at bending radius of 1 cm) and folding (up to angles of 180{\deg}). Moreover, ethylene vinyl acetate-encapsulated MSCs retain their electrochemical properties after a home-laundry cycle, providing waterproof and washable properties for prospective application in wearable electronics

Economic costs of biological invasions in Ecuador:the importance of the Galapagos Islands

Biological invasions, as a result of human intervention through trade and mobility, are the second biggest cause of biodiversity loss. The impacts of invasive alien species (IAS) on the environment are well known, however, economic impacts are poorly estimated, especially in mega-diverse countries where both economic and ecological consequences of these effects can be catastrophic. Ecuador, one of the smallest mega-diverse countries, lacks a comprehensive description of the economic costs of IAS within its territory. Here, using &quot;InvaCost&quot;, a public database that compiles all recorded monetary costs associated with IAS from English and Non-English sources, we investigated the economic costs of biological invasions. We found that between 1983 and 2017, the reported costs associated with biological invasions ranged between US$86.17 million (when considering only the most robust data) and US$626 million (when including all cost data) belonging to 37 species and 27 genera. Furthermore, 99% of the recorded cost entries were from the Galapagos Islands. From only robust data, the costliest identified taxonomic group was feral goats (Capra hircus; US$20 million), followed by Aedes mosquitoes (US$2.14 million) while organisms like plant species from the genus Rubus, a parasitic fly (Philornis downsi), black rats (Rattus rattus) and terrestrial gastropods (Achatina fulica) represented less than US2 million each. Costs of "mixed-taxa" (i.e. plants and animals) represented the highest (61% of total robust costs; US52.44 million). The most impacted activity sector was the national park authorities, which spent about US$84 million. Results from robust data also revealed that management expenditures were the major type of costs recorded in the Galapagos Islands; however, costs reported for medical losses related to Aedes mosquitoes causing dengue fever in mainland Ecuador would have ranked first if more detailed information had allowed us to categorize them as robust data. Over 70% of the IAS reported for Ecuador did not have reported costs. These results suggest that costs reported here are a massive underestimate of the actual economic toll of invasions in the country

Tunable narrowband Excitonic Optical Tamm States enabled by a metal-free all-organic structure

Optical Tamm States (OTS) are confined optical modes that can occur at the interface between two highly reflective structures. However, due to the strong reflectance required, their implemen-tation with highly processable and metal-free flexible materials has proven challenging. Herein, we develop the first structure supporting OTS based only on organic polymeric materials, demon-strating a photonic platform based on non-critical, widely available, and easily processable mate-rials. The structures fabricated present large areas and consist of a narrowband multi-layered polymeric Distributed Bragg Reflector (DBR) followed by a thin film of J-aggregate molecular exci-tonic material that can act as a highly reflective surface within a narrowband range. We take ad-vantage of the narrowband spectral response of the DBR and of the reflective molecular layer to tune the OTS band by varying the periodicity of the multilayer, opening the door for the fabrica-tion of OTS structures based on lightweight integrable excitonic devices with cost-effective proce-dures.Comment: 15 pages, 8 (3+5) figures, supplementary information include