ArduiTaM: accurate and inexpensive NMR auto tune and match system

We introduce a low-complexity, low-cost, yet sufficiently accurate automatic tune and match system for NMR and MRI applications. The ArduiTaM builds upon an Arduino Uno embedded system that drives a commercial frequency synthesiser chip to perform a frequency sweep around the Larmor frequency. The generated low-power signal is fed to the NMR coil, after which the reflected waves are detected using a directional coupler and amplified. The signal shape is then extracted by means of an envelope detector and passed on to the Arduino, which performs a dip search while continuously generating actuator control patterns to adjust the tune and match capacitors. The process stops once the signal dip reaches the Larmor frequency. The ArduiTaM works readily with any spectrometer frequency in the range from 1 to 23&thinsp;T. The speed of the ArduiTaM is mainly limited by the clock of the Arduino and the capacitor actuation mechanism. The Arduino can easily be replaced by a higher-speed microcontroller, and varactors can replace stepper-motor controlled variable capacitors. The ArduiTaM is made available in open source, and so is easily duplicated.</p

C-590T promoter polymorphism of the interleukin (IL)-4 gene is associated with an increased susceptibility to nasal polyposis

Background: Recent studies have shown interleukin 4 (IL-4) and 5 lipoxygenase (5-LO) to play an important role in development of nasal polyposis. Investigation into the genetic factors associated with allergic and nonallergic nasal polyposis has been examined for more than fifteen years. Despite these efforts, the genetic factors underlying the development of nasal polyposis have yet to be clearly understood. The current study examined the relationship between C-590T promoter polymorphisms of the IL-4 gene and the presence of nasal polyps. Additionally, we examined the levels of 5-LO expression in nasal polyp tissue and its association with the IL-4 promoter gene polymorphisms. Methods: A total of 320 subjects were enrolled in the study, of which 256 were healthy controls and 64 were patients with nasal polyps. The Real-Time PCR HRM-based method was used to determine the genotypes of IL-4 C-590T. The expression of 5-LO within the 64 samples of nasal polyp tissue was determined by immunohistochemical staining to examine the association of 5-LO with the IL-4 C-590T genotype. Results: Genetic analysis showed a significant difference in the frequencies of the IL-4 polymorphisms at C-590T in patients with nasal polyps as compared with controls (p < 0.001). No significant difference was seen in the expression of 5-LO among genotypes in patients with nasal polyps (p=0.139). Conclusions: The results suggest that the inheritance of TT and CT genotypes at the IL-4 C-590T promoter gene is associated with nasal polyps however, there is no association between the expression of 5-LO in nasal polyp tissues and IL-4 C-590T genotypes in patients with nasal polyps. © 2015 Reports of Biochemistry and Molecular Biology

Fidelity threshold of the surface code beyond single-qubit error models

The surface code is one the most promising alternatives for implementing fault-tolerant, large-scale quantum information processing. Its high threshold for single-qubit errors under stochastic noise is one of its most attrative features. We develop an exact formulation for the fidelity of the surface code that allows us to probe much further on this promise of strong protection. This formulation goes beyond the stochastic single-qubit error model approximation and can take into account both correlated errors and inhomogeneities in the coupling between physical qubits and the environment. For the case of a bit-flipping environment, we map the complete evolution after one quantum error correction cycle onto the problem of computing correlation functions of a two-dimensional Ising model with boundary fields. Exact results for the fidelity threshold of the surface code are then obtained for several relevant types of noise. Analytical predictions for a representative case are confirmed by Monte Carlo simulations.Comment: 12 pages, 6 figures; revised and extended versio