3,924 research outputs found

    Expanding Carceral Frontiers: The 100-Mile Border Zone and Constituting Latinx Political Subjectivity

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    The thesis has two interrelated concerns. The first explores the emergence of the 100-mile border zone in order to study how the U.S. has expanded its borders inward and redefined notions of national security and carcerality. The second will define the 100-mile border as a carceral frontier that has emerged from previous years of racial security operations such as “Operation Wetback” in 1953. Moreover, I will demonstrate how the 100-mile border zone, a carceral frontier, blends the logic of security and the carceral in order to create a space of total state control. This inward turn of the 100-mile border zone and the security and carcerality of this space reveals much about the constitution of the sovereign state’s right to define and secure its borders within the nation, the rights of the state over that of the citizen, a citizen\u27s right to free movement and due process, and the racial dynamics of security actions. To explore this contradictory logic of security, I conduct an analysis of security language on border and immigration “operations” that constituted the emergence of the 100-mile border zone since 1953. Through this analysis, I will argue that the 100-mile border zone, as a carceral frontier, is a new theoretical development in Critical Carceral Studies. In this way, this thesis will engage in Securitization Studies, Border Theory, and Carceral theories. This type of analysis will reveal that the 100-mile border zone, and the making of this carceral frontier, is inextricably bound to the rights and status of Latinx

    Electron Power-Law Spectra in Solar and Space Plasmas

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    Particles are accelerated to very high, non-thermal energies in solar and space plasma environments. While energy spectra of accelerated electrons often exhibit a power law, it remains unclear how electrons are accelerated to high energies and what processes determine the power-law index δ\delta. Here, we review previous observations of the power-law index δ\delta in a variety of different plasma environments with a particular focus on sub-relativistic electrons. It appears that in regions more closely related to magnetic reconnection (such as the `above-the-looptop' solar hard X-ray source and the plasma sheet in Earth's magnetotail), the spectra are typically soft (δ≳\delta \gtrsim 4). This is in contrast to the typically hard spectra (δ≲\delta \lesssim 4) that are observed in coincidence with shocks. The difference implies that shocks are more efficient in producing a larger non-thermal fraction of electron energies when compared to magnetic reconnection. A caveat is that during active times in Earth's magnetotail, δ\delta values seem spatially uniform in the plasma sheet, while power-law distributions still exist even in quiet times. The role of magnetotail reconnection in the electron power-law formation could therefore be confounded with these background conditions. Because different regions have been studied with different instrumentations and methodologies, we point out a need for more systematic and coordinated studies of power-law distributions for a better understanding of possible scaling laws in particle acceleration as well as their universality.Comment: 67 pages, 15 figures; submitted to Space Science Reviews; comments welcom

    Electromagnetic Sensor and Actuator Attacks on Power Converters for Electric Vehicles

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    Alleviating range anxiety for electric vehicles (i.e., whether such vehicles can be relied upon to travel long distances in a timely manner) is critical for sustainable transportation. Extremely fast charging (XFC), whereby electric vehicles (EV) can be quickly recharged in the time frame it takes to refuel an internal combustion engine, has been proposed to alleviate this concern. A critical component of these chargers is the efficient and proper operation of power converters that convert AC to DC power and otherwise regulate power delivery to vehicles. These converters rely on the integrity of sensor and actuation signals. In this work the operation of state-of-the art XFC converters is assessed in adversarial conditions, specifically against Intentional Electromagnetic Interference Attacks (IEMI). The targeted system is analyzed with the goal of determining possible weak points for IEMI, viz. voltage and current sensor outputs and gate control signals. This work demonstrates that, with relatively low power levels, an adversary is able to manipulate the voltage and current sensor outputs necessary to ensure the proper operation of the converters. Furthermore, in the first attack of its kind, it is shown that the gate signal that controls the converter switches can be manipulated, to catastrophic effect; i.e., it is possible for an attacker to control the switching state of individual transistors to cause irreparable damage to the converter and associated systems. Finally, a discussion of countermeasures for hardware designers to mitigate IEMI-based attacks is provided.Comment: Accepted by IEEE S&P Workshop on the Internet of Safe Things 202

    Branding the nation: Towards a better understanding

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    This paper aims to clarify some misunderstanding about nation branding. It examines the origins and interpretations of the concept, and draws a comparison between nation branding and commercial branding. A new definition is offered that emphasises the need to shift from “branding” the nation to nation image management

    Energy Level Statistics of the U(5) and O(6) Symmetries in the Interacting Boson Model

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    We study the energy level statistics of the states in U(5) and O(6) dynamical symmetries of the interacting boson model and the high spin states with backbending in U(5) symmetry. In the calculations, the degeneracy resulting from the additional quantum number is eliminated manually. The calculated results indicate that the finite boson number NN effect is prominent. When NN has a value close to a realistic one, increasing the interaction strength of subgroup O(5) makes the statistics vary from Poisson-type to GOE-type and further recover to Poisson-type. However, in the case of N→∞N \to \infty, they all tend to be Poisson-type. The fluctuation property of the energy levels with backbending in high spin states in U(5) symmetry involves a signal of shape phase transition between spherical vibration and axial rotation.Comment: 38 pages, 13 figure

    Influence of Si doping on InAs/GaAs quantum dot solar cells with AlAs cap layers

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    A novel all-optical forward-viewing photoacoustic probe using a flexible coherent fibre-optic bundle and a Fabry- Perot (FP) ultrasound sensor has been developed. The fibre bundle, along with the FP sensor at its distal end, synthesizes a high density 2D array of wideband ultrasound detectors. Photoacoustic waves arriving at the sensor are spatially mapped by optically scanning the proximal end face of the bundle in 2D with a CW wavelength-tunable interrogation laser. 3D images are formed from the detected signals using a time-reversal image reconstruction algorithm. The system has been characterized in terms of its PSF, noise-equivalent pressure and field of view. Finally, the high resolution 3D imaging capability has been demonstrated using arbitrary shaped phantoms and duck embryo

    Si-Doped InAs/GaAs Quantum-Dot Solar Cell With AlAs Cap Layers

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    One of the requirements for strong subbandgap photon absorption in the quantum-dot intermediate-band solar cell (QD-IBSC) is the partial filling of the intermediate band. Studies have shown that the partial filling of the intermediate band can be achieved by introducing Si doping to the QDs. However, the existence of too many Si dopants leads to the formation of point defects and, hence, a reduction of photocurrent. In this study, the effect of Si doping on InAs/GaAs QD solar cells with AlAs cap layers is studied. The AlAs cap layers prevent the formation of the wetting layer during QD growth and reduce the Si doping density needed to achieve QD state filling. Furthermore, the passivation of defect states in the QD with moderate Si doping is demonstrated, which leads to an enhancement of the carrier lifetime in the QDs and, hence, the open-circuit voltage

    Expression of monolysocardiolipin acyltransferase activity is regulated in concert with the level of cardiolipin and cardiolipin biosynthesis in the mammalian heart

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    BACKGROUND: Monolysocardiolipin acyltransferase (MLCL AT) catalyzes the acylation of monolysocardiolipin to cardiolipin in mammalian tissues. We previously reported that cardiac cardiolipin levels, MLCL AT and cardiolipin synthase activities were all elevated in rats made hyperthyroid by thyroxine treatment. In this study, we examined if cardiac mitochondrial MLCL AT activity was dependent upon the biosynthesis and level of cardiolipin in the heart. Rat heart mitochondrial MLCL AT activity was determined under conditions in which the levels of cardiac cardiolipin and cardiolipin synthase activity were either reduced or unaltered using four different disease models in the rat. In addition, these parameters were examined in a murine model of cardiac cell differentiation. RESULTS: In rats made hypothyroid by treatment with 6-n-propyl-2-thiouracil in the drinking water for 34 days, cardiac cardiolipin content was decreased 29% (p < 0.025) and this was associated with a 32% decrease (p < 0.025) in cardiolipin synthase and a 35% reduction (p < 0.025) in MLCL AT activities. Streptozotocin-induced diabetes or hyperinsulinemia in rats did not affect cardiac cardiolipin content nor MLCL AT and cardiolipin synthase activities. Finally, cardiolipin content, MLCL AT and cardiolipin synthase activities were unaltered during murine P19 teratocarcinoma cell differentiation into cardiac myocytes. In all models, phospholipase A(2) activities were unaltered compared with controls. CONCLUSION: We propose a general model in which the expression of MLCL AT activity is regulated in concert with the biosynthesis and level of cardiolipin in the heart

    Modeling electron temperature profiles in the pedestal with simple formulas for ETG transport

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    This paper reports on the refinement (building on Ref.~\cite{hatch_22}) and application of simple formulas for electron heat transport from electron temperature gradient (ETG) driven turbulence in the pedestal. The formulas are improved by (1) improving the parameterization for certain key parameters and (2) carefully accounting for the impact of geometry and shaping in the underlying gyrokinetic simulation database. Comparisons with nonlinear gyrokinetic simulations of ETG transport in the MAST pedestal demonstrate the model's applicability to spherical tokamaks in addition to standard aspect ratio tokamaks. We identify bounds for model applicability: the model is accurate in the steep gradient region, where the ETG turbulence is largely slab-like, but accuracy decreases as the temperature gradient becomes weaker in the pedestal top and the instabilities become increasingly toroidal in nature. We use the formula to model the electron temperature profile in the pedestal for four experimental scenarios while extensively varying input parameters to represent uncertainties. In all cases, the predicted electron temperature pedestal exhibits extreme sensitivity to separatrix temperature and density, which has implications for core-edge integration. The model reproduces the electron temperature profile for high Ρe=Lne/LTe\eta_e = L_{ne}/L_{Te} scenarios but not for low Ρe\eta_e scenarios in which microtearing modes have been identified. We develop a proof-of-concept model for MTM transport and explore the relative roles of ETG and MTM in setting the electron temperature profile. We propose that pedestal scenarios predicted for future devices should be tested for compatibility with ETG transport

    An Investigation of the Role of Radiative and Nonradiative Recombination Processes in InAs/GaAs 1−x Sb x Quantum Dot Solar Cells

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    An InAs/GaAs0.86 Sb 0.14 quantum dot solar cell and a GaAsSb control cell were investigated using temperature-dependent current density–voltage (J–V), external quantum efficiency, photoluminescence (PL), and electroluminescence (EL) measurements. Thermally activated defect states associated with the GaAsSb matrix material are found to account for the reduction of the performance of the solar cell. The rapid quenching of the PL and EL intensity, along with the shift (above 150 K) of the dominant recombination process during spontaneous emission (EL), further indicates the prevalence of nonradiative processes at elevated temperatures in these systems. These findings are also supported by a reduction in the open-circuit voltage at elevated temperatures in these devices
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