Forged sculpture

Not Include

Plasmonic gold nanodiscs using piezoelectric substrate birefringence for liquid sensing

This article presents the simulation, fabrication, and experimental characterization of a surface plasmonic resonance (SPR) sensor integrated with an acoustic sensing compatible substrate. The SPR sensor is designed to work in the visible region with gold nanodisc arrays fabricated on LiNbO3, which is both piezoelectric and birefringent. A linear relationship between resonance wavelength and varying liquid refractive indices were observed in experiments, and a sensitivity of 165 nm/refractive index unit was obtained. Polarization effects of the birefringent property of the Y-cut LiNbO3 substrate have been investigated, which can also be applied to X-cut LiNbO3. Our study demonstrates the feasibility of an SPR sensor device utilizing a birefringent substrate, which has acoustic wave compatibility and can pave the way toward much more robust and flexible biosensing device

Professional Reading

Review Article: A Primer on S.G. Gorshkov\u27s \u27Sea Power of the State\u2

Organizing Venture Capital: The Rise and Demise of American Research & Development Corporation, 1946–1973

While venture capital (VC) has become an important element of the twentiethcentury US innovation system, few studies have systematically examined the origins and evolution of this financial institution. We take a step in this direction by analyzing the evolution of the early and influential VC firm, American Research & Development Corporation (ARD), in the period that it was independent from 1946 to 1973. We place the creation and subsequent evolution of ARD within its historical context and show how it was an innovation by Boston-area civic elites. Using new historical data, we examine the evolution of ARD’s practices over time. We argue that ARD’s funding model constrained its functioning as a venture capital firm and contributed to its demise. ARD was a pioneering organization whose business model ultimately failed as a newer organizational model, the limited partnership, was created and had a better fit with the business environment. Nevertheless, ARD has had a lasting imprint on the practice of modern venture capital

CMOS compatible metamaterial absorbers for hyperspectral medium wave infrared imaging and sensing applications

We experimentally demonstrate a CMOS compatible medium wave infrared metal-insulator-metal (MIM) metamaterial absorber structure where for a single dielectric spacer thickness at least 93% absorption is attained for 10 separate bands centred at 3.08, 3.30, 3.53, 3.78, 4.14, 4.40, 4.72, 4.94, 5.33, 5.60 μm. Previous hyperspectral MIM metamaterial absorber designs required that the thickness of the dielectric spacer layer be adjusted in order to attain selective unity absorption across the band of interest thereby increasing complexity and cost. We show that the absorption characteristics of the hyperspectral metamaterial structures are polarization insensitive and invariant for oblique incident angles up to 25° making them suitable for practical implementation in an imaging system. Finally, we also reveal that under TM illumination and at certain oblique incident angles there is an extremely narrowband Fano resonance (Q < 50) between the MIM absorber mode and the surface plasmon polariton mode that could have applications in hazardous/toxic gas identification and biosensing

Octave-spanning broadband absorption of terahertz light using metasurface fractal-cross absorbers

Synthetic fractals inherently carry spatially encoded frequency information that renders them as an ideal candidate for broadband optical structures. Nowhere is this more true than in the terahertz (THz) band where there is a lack of naturally occurring materials with valuable optical properties. One example are perfect absorbers that are a direct step toward the development of highly sought after detectors and sensing devices. Metasurface absorbers that can be used to substitute for natural materials suffer from poor broadband performance, while those with high absorption and broadband capability typically involve complex fabrication and design and are multilayered. Here, we demonstrate a polarization-insensitive ultrathin (∼λ/6) planar metasurface THz absorber composed of supercells of fractal crosses capable of spanning one optical octave in bandwidth, while still being highly efficient. A sufficiently thick polyimide interlayer produces a unique absorption mechanism based on Salisbury screen and antireflection responses, which lends to the broadband operation. Experimental peak absorption exceeds 93%, while the average absorption is 83% from 2.82 THz to 5.15 THz. This new ultrathin device architecture, achieving an absorption-bandwidth of one optical octave, demonstrates a major advance toward a synthetic metasurface blackbody absorber in the THz ban

Raytheon -- Additive Manufacturing of Tailored Materials

Sponsored by Raytheon and Dr. Anthony Rafanelli, The Material Tailors are determining whether or not additive manufacturing can be used to tailor material properties. The purpose is to focus on a tailoring specific material properties using a 3D printer filament, depending on manufacturer needs. The material properties chosen to focus on are strength and corresponding Young’s Modulus, yield strength and ultimate tensile strength as well as dimensional stability. In order to accomplish these measures, preliminary measures included finding materials that exhibit strength and durability. As a result, Nylon, ABS, PLA, carbon fiber, carbon fiber reinforced PLA and PETG filaments were chosen. Nylon is a tough material that has high tensile strength and the prints it produces are strong and resistant to damage. However, when printing with this material in 2019, issues arose and printing was discontinued due to time constraints. ABS is a material that is hard to break but it is easily broken down by UV radiation meaning that it is not suitable for long-term outdoor use because it becomes brittle. PLA is the most common filament to use as it is a resilient material, however, it deforms at higher temperatures and is prone to shattering under stress. Carbon fiber and carbon fiber reinforced PLA have similar properties that provide rigidity, strength and are lightweight, however, they are brittle and can be easily fractured. Lastly, PETG is a plastic commonly used in plastic bottles but with additional glycol to add strength. PETG has the useful characteristics of ABS in terms of rigidity and mechanical properties for functional parts along with the ease the printing PLA comes with. It is important to obtain data regarding these material properties to better understand them. This was accomplished by 3D printing using ASTM D638 for a Type 1 dogbone and then tensile testing using an Instron 5582 machine. Further testing such as the flex, dimensional stability and hardness tests yielded values that are critical to the design of a potential product and will be incorporated into a user friendly database for manufacturers in order to determine what material is unparalleled for use. As stated previously, each material used will have strength and corresponding Young’s Modulus that will be tailored in order to understand how these measures react under varying stresses and strains. This is turn, will provide a useful database application that can be used in industry or commercially. As of right now, Raytheon does not require a physical final product but overall research on what material is best to use in a way that it provides high strength and dimensional stability

Measuring Interventional Robustness in Reinforcement Learning

Recent work in reinforcement learning has focused on several characteristics of learned policies that go beyond maximizing reward. These properties include fairness, explainability, generalization, and robustness. In this paper, we define interventional robustness (IR), a measure of how much variability is introduced into learned policies by incidental aspects of the training procedure, such as the order of training data or the particular exploratory actions taken by agents. A training procedure has high IR when the agents it produces take very similar actions under intervention, despite variation in these incidental aspects of the training procedure. We develop an intuitive, quantitative measure of IR and calculate it for eight algorithms in three Atari environments across dozens of interventions and states. From these experiments, we find that IR varies with the amount of training and type of algorithm and that high performance does not imply high IR, as one might expect.Comment: 17 pages, 13 figure

The Epstein–Barr Virus (EBV) DNA Polymerase Accessory Protein, BMRF1, Activates the Essential Downstream Component of the EBV oriLyt

The EBV DNA polymerase accessory protein, BMRF1, is an essential component of the viral DNA polymerase and is required for lytic EBV replication. In addition to its polymerase accessory protein function, we have recently reported that BMRF1 is a transcriptional activator, inducing expression of the essential oriLyt promoter, BHLF1. Here we have precisely mapped the BMRF1-response element in the BHLF1 promoter. We demonstrate that a region of oriLyt (the "downstream component"), previously shown to be one of two domains absolutely essential for oriLyt replication, is required for BMRF1-induced activation of the BHLF1 promoter. Furthermore, the downstream component of oriLyt is sufficient to confer BMRF1-responsiveness to a heterologous promoter. The downstream component contains Sp1 binding sites, and confers Sp1-responsiveness to a heterologous promoter. A series of plasmids containing various protions of the oriLyt downstream component were constructed and analyzed for their ability to respond to the BMRF1 versus Sp1 transactivators. Although the BMRF1-responsive region of the downstream component overlaps the Sp1-responsive element, certain oriLyt sequences required for maximal BMRF1-responsiveness were not required for maximal Sp1-responsiveness. In particular, a site-directed mutation altering the downstream component sequence GATGG (located from -588 to -592 relative to the BHLF1 transcription initiation site) did not affect Sp1-responsiveness, but reduced BMRF-1-responsiveness by 75% and abolished oriLyt replication. Although BMRF1 possesses nonspecific DNA binding activity, were unable to demonstrate specific BMRF1 binding to the downstream component of oriLyt. Our results suggest that BMRF1-induced activation of the essential downstream component of oriLyt may play an important role in oriLyt replication