Nuclear Terrorism: Statutory Shortcomings and Prosecutorial Opportunities

In 2016, President Barack Obama warned that “[t]he danger of a terrorist group obtaining and using a nuclear weapon is one of the greatest threats to global security.” Thus far, however, U.S. and international efforts to address nuclear terrorism have faced a fundamental dilemma: While the importance of preventing this threat is unquestioned, there has been limited opportunity or need to conduct prosecutions that hinge on nuclear terrorism charges. This dilemma reflects the current piecemeal approach to nuclear terrorism, which prioritizes policies that address the “back-end” risk of nuclear terrorism (i.e., the detonation of nuclear weapons or attack of nuclear facilities) over efforts that address the front-end, preparatory steps that a would-be terrorist would take in advance of an attack. Given the importance of developing a more holistic approach to nuclear terrorism, this article proposes that the U.S. government promulgates a clearer framework for federal nuclear terrorism prosecutions. Part I first sets the legal landscape, introducing the key statutory provisions and prosecutions that comprise the existing federal jurisprudence on nuclear terrorism. Part II then evaluates the principal statutory shortcomings in the U.S. criminal system’s current approach to nuclear terrorism. Finally, Part III argues that in order to address these shortcomings, the U.S. Department of Justice (DOJ) should craft a nuclear terrorism prosecution framework (NTPF). This proposed framework consists of two guidelines premised on the principles of consistency and coordination and several recommended courses of action

First-principles study of point defects in β-Ga2O3

Gallium oxide (Ga2O3) has been proposed as a promising candidate for power devices. Under the high electric field and high operating temperatures in such power devices, point defects are expected to form in Ga2O3 that can limit the device performance. We have calculated the thermodynamic stability of intrinsic point defects in stable monoclinic β-Ga2O3, such as VO, VGa, Oi, Gai, OGa, and GaO, under various chemical and electron potential using first-principles density functional theory calculations. We find that Vo, Gai, and GaO exhibit deep donor levels in gallium-rich conditions and do not contribute to n-type doping. GaO and Gai have high formation energy at low fermi levels in oxygen-rich conditions and can act as electron acceptors

First principles calculation of polarization induced interfacial charges in GaN/AlN heterostructures

We propose a new method to calculate polarization induced interfacial charges in semiconductor heterostructures using classical electrostatics applied to real-space band diagrams from first principles calculations and apply it to GaN/AlN heterostructures with ultrathin AlN layers (4-6 monolayers). We show that the calculated electric fields and interfacial charges are independent of the exchange-correlation functionals used (local-density approximation and hybrid functionals). We also find the calculated interfacial charge of (6.8 +/- 0.4) x 10^13 cm-2 to be in excellent agreement with experiments and the value of 6.58 x 10^13 cm-2 calculated from bulk polarization constants, validating the use of bulk constants even for very thin films.Comment: 3 pages, 2 figures; submitted to Applied Physics Letter

Modeling Temperature, Frequency, and Strain Effects on the Linear Electro-Optic Coefficients of Ferroelectric Oxides

An electro-optic modulator offers the function of modulating the propagation of light in a material with electric field and enables seamless connection between electronics-based computing and photonics-based communication. The search for materials with large electro-optic coefficients and low optical loss is critical to increase the efficiency and minimize the size of electro-optic devices. We present a semi-empirical method to compute the electro-optic coefficients of ferroelectric materials by combining first-principles density-functional theory calculations with Landau-Devonshire phenomenological modeling. We apply the method to study the electro-optic constants, also called Pockels coefficients, of three paradigmatic ferroelectric oxides: BaTiO3, LiNbO3, and LiTaO3. We present their temperature-, frequency- and strain-dependent electro-optic tensors calculated using our method. The predicted electro-optic constants agree with the experimental results, where available, and provide benchmarks for experimental verification.Comment: 30 pages, 6 figures, 2 tables and 2 boxe

GSM Based Display ToolKit

Wireless communication has announced its arrival on big stage and the world is going mobile. We want to control everything and without moving an inch. This remote control of appliances is possible through Embedded Systems. The use of “Embedded System in Communication” has given rise to many interesting applications that ensures comfort and safety to human life. The main aim of the project will be to design a SMS driven automatic display toolkit which can replace the currently used programmable electronic display. It is proposed to design receive cum display toolkit which can be programmed from an authorized mobile phone. The message to be displayed is sent through a SMS from an authorized transmitter. The toolkit receives the SMS, validates the sending Mobile Identification Number (MIN) and displays the desired information after necessary code conversion. The system is made efficient by using ‘clone’ SIMs of same MIN in a geographical area so that the same SMS can be received by number of display boards in a locality using techniques of time division multiple access. Started of as an instantaneous News display unit, we have improved upon it and tried to take advantage of the computing capabilities of microcontroller. We envision a toolkit that will not only display message but also can be used to do some mechanical work

Stabilizing polar phases in binary metal oxides by hole doping

The recent observation of ferroelectricity in the metastable phases of binary metal oxides, such as HfO2, ZrO2, Hf0.5Zr0.5O2, and Ga2O3, has garnered a lot of attention. These metastable ferroelectric phases are typically stabilized using epitaxial strain, alloying, or defect engineering. Here, we propose that hole doping plays a key role in the stabilization of polar phases in binary metal oxides. Using first-principles density-functional-theory calculations, we show that holes in these oxides mainly occupy one of the two oxygen sublattices. This hole localization, which is more pronounced in the polar phase than in the nonpolar phase, lowers the electrostatic energy of the system, and makes the polar phase more stable at sufficiently large concentrations.We demonstrate that this electrostatic mechanism is responsible for stabilization of the ferroelectric phase of HfO2 aliovalently doped with elements that introduce holes to the system, such as La and N. Finally, we show that spontaneous polarization in HfO2 is robust to hole doping, and a large polarization persists even under a high concentration of holes