Superconductivity from a melted insulator

Quantum phase transitions typically result in a broadened critical or crossover region at nonzero temperature. Josephson arrays are a model of this phenomenon, exhibiting a superconductor-insulator transition at a critical wave impedance, and a well-understood insulating phase. Yet high-impedance arrays used in quantum computing and metrology apparently evade this transition, displaying superconducting behavior deep into the nominally insulating regime. The absence of critical behavior in such devices is not well understood. Here we show that, unlike the typical quantum-critical broadening scenario, in Josephson arrays temperature dramatically shifts the critical region. This shift leads to a regime of superconductivity at high temperature, arising from the melted zero-temperature insulator. Our results quantitatively explain the low-temperature onset of superconductivity in nominally insulating regimes, and the transition to the strongly insulating phase. We further present, to our knowledge, the first understanding of the onset of anomalous-metallic resistance saturation. This work demonstrates a non-trivial interplay between thermal effects and quantum criticality. A practical consequence is that, counterintuitively, the coherence of high-impedance quantum circuits is expected to be stabilized by thermal fluctuations.Comment: 8+18 pages, 4+15 figure

Resistance of Human Cytomegalovirus to Cyclopropavir Maps to a Base Pair Deletion in the Open Reading Frame of \u3cem\u3eUL97\u3c/em\u3e

Human cytomegalovirus (HCMV) is a widespread pathogen in the human population, affecting many immunologically immature and immunocompromised patients, and can result in severe complications, such as interstitial pneumonia and mental retardation. Current chemotherapies for the treatment of HCMV infections include ganciclovir (GCV), foscarnet, and cidofovir. However, the high incidences of adverse effects (neutropenia and nephrotoxicity) limit the use of these drugs. Cyclopropavir (CPV), a guanosine nucleoside analog, is 10-fold more active against HCMV than GCV (50% effective concentrations [EC50s] = 0.46 and 4.1 μM, respectively). We hypothesize that the mechanism of action of CPV is similar to that of GCV: phosphorylation to a monophosphate by viral pUL97 protein kinase with further phosphorylation to a triphosphate by endogenous kinases, re- sulting in inhibition of viral DNA synthesis. To test this hypothesis, we isolated a CPV-resistant virus, sequenced its genome, and discovered that bp 498 of UL97 was deleted. This mutation caused a frameshift in UL97 resulting in a truncated protein that lacks a kinase domain. To determine if this base pair deletion was responsible for drug resistance, the mutation was engineered into the wild-type viral genome, which was then exposed to increasing concentrations of CPV. The results demonstrate that the engineered virus was approximately 72-fold more resistant to CPV (EC50 = 25.8 ± 3.1 μM) than the wild-type virus (EC50 = 0.36 ± 0.11 μM). We conclude, therefore, that this mutation is sufficient for drug resistance and that pUL97 is involved in the mechanism of action of CPV

Observation of collapse and revival in a superconducting atomic frequency comb

Recent advancements in superconducting circuits have enabled the experimental study of collective behavior of precisely controlled intermediate-scale ensembles of qubits. In this work, we demonstrate an atomic frequency comb formed by individual artificial atoms strongly coupled to a single resonator mode. We observe periodic microwave pulses that originate from a single coherent excitation dynamically interacting with the multi-qubit ensemble. We show that this revival dynamics emerges as a consequence of the constructive and periodic rephasing of the five superconducting qubits forming the vacuum Rabi split comb. In the future, similar devices could be used as a memory with in-situ tunable storage time or as an on-chip periodic pulse generator with non-classical photon statistics

Response of Captive Coyotes to Renardine Coyote Repellent

Renardine is a bone tar product available for use as a coyote (Canis latrans) repellent in Canada. The substance is applied to pasture borders to prevent coyotes from entering and attacking sheep. Because data regarding the effectiveness of Renardine are lacking, we designed two experiments. In the first, six pairs of coyotes were first presented with 400 g of ground meat in two pans (200 g/pan) with false screen bottoms. Beneath the screens were absorbent tubes wetted with 10 ml of distilled water. Subsequently, during a treatment period, the absorbent tube was wetted with 10 ml of Renardine. Pans were presented for 60 minutes, and the amount of time to consume the meat was recorded. In the second experiment, six additional pairs of coyotes were first presented with 200 g of ground meat inside a barrier created with baling twine and wooden dowels. The area inside the barrier was 1 m2, and the twine was tied onto the dowels 0.25 m above the ground. During the treatment period, the twine and dowels were painted with Renardine. In both experiments, all coyote pairs consumed all of the ground meat shortly after presentation. We conclude that Renardine probably is not an effective coyote repellent. However, because the active ingredient in Renardine is bone tar oil and bone tar oil is deer repellent, we speculate that Renardine may have utility as an herbivore repellent

DEVELOPMENT AND REGISTRATION OF A PRACTICAL TRANQUILIZER TRAP DEVICE (TTD) FOR FOOT-HOLD TRAPS

Foot-hold traps can be used to selectively capture coyotes (Canis latrans) and wolves (C. lupus). However, injuries to captured animals sometimes occur when they struggle to escape. Tranquilizer trap devices (TTDs) reduce struggling and injuries but prototype TTDs were too expensive for widespread use by Animal Damage Control (ADC) operational personnel. For this reason, the Pocatello Supply Depot (PSD) and the National Wildlife Research Center (NWRC) are investigating alternative TTD designs. A molded-rubber TTD will be available from the PSD for coyotes, and the NWRC continues to explore other cheaper TTD designs. A practical TTD design is now available for use with wolves, and evaluation of foot and leg injuries shows \u3e90% of wolves captured in TTD equipped foot-hold traps had only minor injuries. Conversely, 57% of wolves captured in traps without the tranquilizer had more severe injuries. A training handbook is being developed by ADC operations and NWRC personnel for the operational use of TTDs. The development of efficient, economical tranquilizer delivery systems continues to be an important priority for the NWRC

Brachyview: An in-body imaging system for real-time QA in HDR prostate brachytherapy

A transrectal real-time source tracking system, BrachyView, is developed by Centre for Medical Radiation Physics at University of Wollongong for treatment quality control during the high dose rate prostate brachytherapy procedure (HDR-PBT). The probe consists of a 15 × 60 mm2 pixellated silicon detector (four Timepix detectors) encased in a cylindrical seven pinhole tungsten collimator. The source position is determined by back-projecting the source projection images through the collimator pinholes. A prototype BrachyView probe consisting of a single Timepix detector (15 × 15 mm2) and a planar seven pinhole collimator is evaluated in this paper. The source position can be estimated with a maximum error of 0.2 mm on the detector plane, which translates into a maximum error of 1.42 mm within the prostate volume. This result is in good agreement with the results obtained in previously published simulation studies. © 2013 IEEE