Position Dependent Response of Superconducting MgB2 Neutron Detectors Studied by Pulsed Laser Irradiation

The MgB₂ detector consists of 200?nm thick MgB₂ thin film meander structure of 3?μm line width protected by 300?nm thick SiO layer. The electrical connections were provided by 150?nm thick Nb. The devices were placed in a 4?K refrigerator to investigate the behavior at temperatures below T _c. The position-dependent response of the MgB₂ detector can be investigated by scanning a laser spot with the aid of the XYZ piezo-driven stage and an optical fiber with a focusing lens. We found that the inhomogeneity in a detector is very critical to specify the detection efficiency since the detector has the sensitivity only in a narrow temperature regime near T _c.     

Effectiveness and limitations of the fallback I algorithm for transient supraventricular tachyarrhythmias in DDD pacing

To examine the function of the fallback I algorithm (Chorus I, Ela Medical Inc., Montrouge, France), which automatically changes the DDD mode to VDI during transient supraventricular tachyarrhythmias to prevent high-rate tracking of the venticule, a total of 45 patients who were preoperatively diagnosed with sick-sinus syndrome (SSS) (Group 1; n = 19) or with advanced or complete atrioventricular block (AVB) (Group 2; n = 26) were followed up and analyzed. Mean follow-up times (mean +/- SD) were 22.4 +/- 9.7 and 12.4 +/- 10.9 months, respectively. Each of the groups was further divided into subgroups according to the preoperative existence of of paroxysmal atrial fibrillation (PAF) or paroxysmal supraventricular tachyarrhythmia (PSVT). During follow-up, the fallback started through a given cycle of ventricular pacing at a upper-rate limit (URL) to avoid a continuous high-rate tracking during the arrhythmias specifically in the patients with PSVT (0/4) (p = 0.0004). The fallback, however, sometimes started in the patients who had AVB not associated with either PAF or PSVT (4/21) during normal exercise because the fallback algorithm did not distinguish a normal P wave from the abnormal atrial waves. To further clarify the behavior of the fallback, a treadmill test was conducted in 25 of the 45 patients. The fallback start was observed in 12 of the 17 patients with AVB (Group 2). In such patients, the use of a long fallback delay and/or a high URL setting prevented the fallback starts during normal exercise. These results suggest that, in DDD pacing, the algorithm in Chorus I is useful in patients with SSS or AVB to avoid highrate tracking of the ventricle during transient supraventricular tachyarrhythmias, but special care must be taken to avoid the fallback starts during the normal exercise in AVB patients.     

Dust absorption averaged over the Sahara inferred from moderate resolution imaging spectroradiometer

We estimated the average dust single scattering albedo (omega(0)) over the Sahara using four years of moderate resolution imaging spectroradiometer data. The method employed is based on the theory that the critical surface reflectance (rho(c)) for which the reflectance at the top-of-the-atmosphere is not influenced by the variability of dust optical thickness depends on omega(0). The average dust absorption over the Sahara was estimated to be smaller than that previously reported in the literature, and this may be causing the cooling of the climate system. Our method enables one to estimate omega(0) from data with a variety of aerosol optical thickness values using samples in the vicinity of rho(c). Use of satellite data over large areas and for long periods enables quantification of the average dust absorption over the entire Sahara.     

A Method for Distinguishing the Two Candidate Elliptic Curves in the Complex Multiplication Method

In this paper, we particularly deal with no F_p‐rational two‐torsion elliptic curves, where F_p is the prime field of the characteristic p. First we introduce a shift product‐based polynomial transform. Then, we show that the parities of (#E – 1)/2 and (#E’ – 1)/2 are reciprocal to each other, where #E and #E’ are the orders of the two candidate curves obtained at the last step of complex multiplication (CM)‐based algorithm. Based on this property, we propose a method to check the parity by using the shift product‐based polynomial transform. For a 160 bits prime number as the characteristic, the proposed method carries out the parity check 25 or more times faster than the conventional checking method when 4 divides the characteristic minus 1. Finally, this paper shows that the proposed method can make CM‐based algorithm that looks up a table of precomputed class polynomials more than 10 percent faster.