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A high-performance 3–6 GHz monolithic digital control attenuator chip is designed by using a 0.25 μm GaAs pHEMT process. The circuit adopts a cascade structure of 6 basic attenuation units, and 64 attenuation states are formed by controlling the on-state combination of different attenuation bits, and the attenuation structure connected in parallel to the attenuation resistor is given. The main simulation results show that the designed digitally controlled attenuator takes 0.5dB as the attenuation step, and the maximum attenuation value is 31.5 dB, an insertion loss of less than 2.55 dB, a return loss better than -15 dB, an attenuation accuracy of less than 0.5 dB for all states, an additional phase shift of less than -5°, a root mean square error better than 0.23 dB of attenuation amplitude, and chip size of 1.88 mm×1.0 mm.

Formula Student competitions require several standard safety devices, one of which is the impact attenuator. The impact attenuator is installed at the front of the car to absorb energy during a collision, thereby protecting the driver from direct impact. While the shapes and materials of impact attenuators vary widely, many are costly and have limited availability. This study tested the feasibility of using used food cans as an alternative material for impact attenuators. Four variations were tested to determine which combination of materials offers the best energy absorption. The variations included an aluminum blanket alone, stacked cans, a combination of stacked cans and blankets, and a combination of stacked cans with blankets plus polyurethane foam. The analysis was conducted based on compressive testing results using a Universal Testing Machine. The study found weaknesses in the use of incorrect hole designs and overly thin partitions. The most optimal energy absorption, 6,969.2 J, was achieved in the fourth variation, which included polyurethane foam. The results suggest that used food cans have potential as an alternative material for impact attenuators.

The Solar Wind Ion Analyzer (SWIA) on the MAVEN mission will measure the solar wind ion flows around Mars, both in the upstream solar wind and in the magneto-sheath and tail regions inside the bow shock. The solar wind flux provides one of the key energy inputs that can drive atmospheric escape from the Martian system, as well as in part controlling the structure of the magnetosphere through which non-thermal ion escape must take place. SWIA measurements contribute to the top level MAVEN goals of characterizing the upper atmosphere and the processes that operate there, and parameterizing the escape of atmospheric gases to extrapolate the total loss to space throughout Mars’ history. To accomplish these goals, SWIA utilizes a toroidal energy analyzer with electrostatic deflectors to provide a broad 360 ∘ ×90 ∘ field of view on a 3-axis spacecraft, with a mechanical attenuator to enable a very high dynamic range. SWIA provides high cadence measurements of ion velocity distributions with high energy resolution (14.5 %) and angular resolution (3.75 ∘ ×4.5 ∘ in the sunward direction, 22.5 ∘ ×22.5 ∘ elsewhere), and a broad energy range of 5 eV to 25 keV. Onboard computation of bulk moments and energy spectra enable measurements of the basic properties of the solar wind at 0.25 Hz.

A robust cryogenic infrastructure in form of a wired, thermally optimized dilution refrigerator is essential for solid-state based quantum processors. Here, we engineer a cryogenic setup, which minimizes passive and active heat loads, while guaranteeing rapid qubit control and readout. We review design criteria for qubit drive lines, flux lines, and output lines used in typical experiments with superconducting circuits and describe each type of line in detail. The passive heat load of stainless steel and NbTi coaxial cables and the active load due to signal dissipation are measured, validating our robust and extensible concept for thermal anchoring of attenuators, cables, and other microwave components. Our results are important for managing the heat budget of future large-scale quantum computers based on superconducting circuits.

Drought stress limits cucumber germination and initial growth. Decreases cucumber germination and initial growth cause uneven plant stands and decrease crop productivity. Identifying drought-tolerant cultivars and drought stress attenuators can improve cucumber germination and initial growth. Therefore, we evaluated the drought stress tolerance of cucumber cultivars and the action of drought-stress attenuators on cucumber germination, initial growth, osmotic adjustment, and antioxidant activity. The research was carried out in two stages. In the first one, we evaluated five levels of osmotic potential and seven cucumber cultivars. In the second stage, we evaluated two cultivars—one sensitive and one tolerant to drought stress—subjected to six combinations of osmotic potential and attenuator. The osmotic potential of − 0.4 MPa is critical for cucumber seedlings—the cultivars Compadre, Campeiro, Sliced Max, and Prêmio are sensitive, and cultivars Diplomat, Runner, and Safira are tolerant at the − 0.4 MPa level. Sensitive cultivar seeds treated with hydropriming, salicylic acid, and hydrogen peroxide showed better growth, osmotic adjustment, and higher antioxidant activity than seeds not treated under drought stress. Gibberellic acid was beneficial only in the drought-stress tolerant cultivar and can increase the vigor of drought-tolerant cultivars. Our results reveal that Diplomat, Runner, and Safira cucumber cultivars are drought-tolerant and that hydropriming, salicylic acid, and hydrogen peroxide improve the tolerance of drought-sensitive cucumber cultivars.

Gas attenuators are important devices providing accurate variation of photon intensity for soft X‐ray beamlines. In the SwissFEL ATHOS beamline front‐end the space is very limited and an innovative approach has been taken to provide attenuation of three orders of magnitude up to an energy of 1200 eV. Additive manufacturing of a differential pumping system vacuum manifold allowed a triple pumping stage to be realized in a space of less than half a meter. Measurements have shown that the response of the device is as expected from theoretical calculations. A compact gas attenuator for the SwissFEL ATHOS beamline with a custom manifold realized using additive manufacturing is described. First results show that the response is as expected from theoretical calculations.

Thermal attenuator channels model the decoherence of quantum systems interacting with a thermal bath, e.g., a two-level system subject to thermal noise and an electromagnetic signal traveling through a fiber or in free-space. Hence determining the quantum capacity of these channels is an outstanding open problem for quantum computation and communication. Here we derive several upper bounds on the quantum capacity of qubit and bosonic thermal attenuators. We introduce an extended version of such channels which is degradable and hence has a single-letter quantum capacity, bounding that of the original thermal attenuators. Another bound for bosonic attenuators is given by the bottleneck inequality applied to a particular channel decomposition. With respect to previously known bounds we report better results in a broad range of attenuation and noise: we can now approximate the quantum capacity up to a negligible uncertainty for most practical applications, e.g., for low thermal noise. Bounding the capacity of thermal attenuators would give a powerful instrument to describe decoherence occurring in optical fibres and free space links. Here, the authors improve on the existing upper bounds in the region of small thermal noise, which is of interest for quantum communication.

The cellular and molecular basis of sex-dimorphic autoimmune diseases, such as the CNS demyelinating disease multiple sclerosis (MS), remains unclear. Our studies in the SJL mouse model of MS, experimental autoimmune encephalomyelitis (EAE), reveal that sex-determined differences in Il33 expression by innate immune cells in response to myelin peptide immunization regulate EAE susceptibility. IL-33 is selectively induced in PLP139–151-immunized males and activates type 2 innate lymphoid cells (ILC2s), cells that promote and sustain a nonpathogenic Th2 myelin-specific response. Without this attenuating IL-33 response, females generate an encephalitogenic Th17-dominant response, which can be reversed by IL-33 treatment. Mast cells are one source of IL-33 and we provide evidence that testosterone directly induces Il33 gene expression and also exerts effects on the potential for Il33 gene expression during mast cell development. Thus, in contrast to their pathogenic role in allergy, we propose a sex-specific role for both mast cells and ILC2s as attenuators of the pathogenic Th response in CNS inflammatory disease.

Three-dimensional printing is widely becoming prevalent in various industries, including the automotive sector. As this technology advances, critical structures subjected to impact loads may also be produced using additive manufacturing. A key parameter in this technique is the infill density of the printed geometry, which directly affects mechanical properties such as strength, stiffness, and ductility. Functionally graded layouts present themselves as one of the best techniques to design effective impact attenuators. The present work combines these techniques and parameters to evaluate the behaviour of geometrically graded impact attenuators produced through additive manufacturing, with different infill densities for polylactic acid (PLA) and polycarbonate (PC) materials. The results obtained show an increase in the mechanical strength for both materials and all the infill densities when compared to reference quasi-static results.

This article reports on a novel configuration of a balanced power amplifier (BPA) architecture that enables adaptive voltage standing wave ratio (VSWR) protection. The BPA topology is modified at its input using a wideband power divider and two step‐attenuators to control the power level distribution of RF signals driving the inputs of the 0°–90° hybrid coupler. In doing so, a certain degree of imbalance is advantageously practised to ensure a prescribed VSWR at the transistor's drain ports. The strategy followed to control the step‐attenuator values as a function of the targeted VSWR is detailed. A conventional closed‐loop VSWR detection and correction has been implemented in a demonstrator including commercial off‐the‐shelf (COTS) components at S‐band to validate the proposed concept. A novel configuration of a balanced power amplifier (BPA) radio‐frequency (RF) architecture that enables an adaptive voltage standing wave ratio (VSWR) protection is proposed. A conventional closed‐loop VSWR detection and correction has been implemented in a demonstrator.