A high order feedback net (HOFNET) with variable non-linearity

Most neural networks proposed for pattern recognition sample the incoming image at one instant and then analyse it. This means that the data to be analysed is limited to that containing the noise present at one instant. Time independent noise is therefore, captured but only one sample of time dependent noise is included in the analysis. If however, the incoming image is sampled at several instants, or continuously, then in the subsequent analysis the time dependent noise can be averaged out. This, of course, assumes that sufficient samples can be taken before the object being imaged, has moved an appreciable distance in the field of view. High speed sampling requires parallel image input and is most conveniently carried out by optoelectronic neural network image analysis systems. Optical technology is particularly good at performing certain operations, such as Fourier Transforms, correlations and convolutions while others such as subtraction are difficult. So for an optical net it is best to choose an architecture based on convenient operations such as the high order neural networks

Opto-electronic high order feedback neural network

A novel neural network design, in which nonlinearities are created by feedback, is described. It is called the HOFNET. The design is suitable for optical implementation because it is tolerant of the limited dynamic ranges present in optical systems. An optical system with electronic feedback was constructed and its operation is described

Detailed study of the ac susceptibility of Sr2RuO4 in oriented magnetic fields

We have investigated the ac susceptibility of the spin triplet superconductor Sr$_2$RuO$_4$ as a function of magnetic field in various directions at temperatures down to 60 mK. We have focused on the in-plane field configuration (polar angle $\theta \simeq 90^{\circ}$), which is a prerequisite for inducing multiple superconducting phases in Sr$_2$RuO$_4$. We have found that the previous attribution of a pronounced feature in the ac susceptibility to the second superconducting transition itself is not in accord with recent measurements of the thermal conductivity or of the specific heat. We propose that the pronounced feature is a consequence of additional involvement of vortex pinning originating from the second superconducting transition.Comment: Accepted for publication in Phys. Rev.

Ne22(d,p)23Ne reaction and neutron balance in the s process

One possible source of neutrons for the astrophysical s process is the Ne22(n)25Mg reaction. However, the number of neutrons available to synthesize heavy elements may be limited by the rate of the Ne22(n,)23Ne reaction. To aid in the interpretation of recent (n,) measurements, we have used the Ne22(d,p)23Ne reaction to investigate the single-particle structure of states located near the Ne22+n threshold. No states that correspond to astrophysically significant resonances were found, and so the (n,) rate is effectively determined by direct capture

Interface superconductivity in the eutectic Sr2RuO4-Ru: 3-K phase of Sr2RuO4

The eutectic system Sr2RuO4-Ru is referred to as the 3-K phase of the spin-triplet supeconductor Sr2RuO4 because of its enhanced superconducting transition temperature Tc of ~3 K. We have investigated the field-temperature (H-T) phase diagram of the 3-K phase for fields parallel and perpendicular to the ab-plane of Sr2RuO4, using out-of-plane resistivity measurements. We have found an upturn curvature in the Hc2(T) curve for H // c, and a rather gradual temperature dependence of Hc2 close to Tc for both H // ab and H // c. We have also investigated the dependence of Hc2 on the angle between the field and the ab-plane at several temperatures. Fitting the Ginzburg-Landau effective-mass model apparently fails to reproduce the angle dependence, particularly near H // c and at low temperatures. We propose that all of these charecteric features can be explained, at least in a qualitative fashion, on the basis of a theory by Sigrist and Monien that assumes surface superconductivity with a two-component order parameter occurring at the interface between Sr2RuO4 and Ru inclusions. This provides evidence of the chiral state postulated for the 1.5-K phase by several experiments.Comment: 7 pages and 5 figs; accepted for publication in Phys. Rev.

Comment on "Experimental determination of superconducting parameters for the intermetallic perovskite superconductor MgCNi3_3"

In a recent paper (Phys. Rev. {\bf B 67}, 094502 (2003)) Mao et al. investigated the bias-dependent conductance of mechanical junctions between superconducting MgCNi$_3$ and a sharp W tip. They interpreted their results in terms of 'single-particle tunneling'. We show it is more likely that current transport through those junctions is determined by thermal effects due to the huge normal-state resistivity of MgCNi$_3$. Therefore no conclusion can be drawn about the possible unconventional pairing or strong-coupling superconductivity in MgCNi$_3$.Comment: 2 pages, 1 Fig. Comment on Z. Q. Mao et al. (Phys. Rev. {\bf B 67}, 094502 (2003)

Decay of the first isobaric analog state in Ge69

The alpha-decay branching ratio for the lowest isobaric analog state in Ge69 has been measured to be less than 1.0×10-2. Transitions to this level contribute significantly to the cross section for the capture of high-energy neutrinos by Ga69. Since the analog state decays almost exclusively by gamma-ray emission, induced Ge69 radioactivity may be used for the detection of high-energy neutrinos in large-scale gallium neutrino detectors

Elastic Tensor of Sr2_2RuO4_4

The six independent elastic constants of Sr$_2$RuO$_4$ were determined using resonant ultrasound spectroscopy on a high-quality single-crystal specimen. The constants are in excellent agreement with those obtained from pulse-echo experiments performed on a sample cut from the same ingot. A calculation of the Debye temperature using the measured constants agrees well with values obtained from both specific heat and M\"{o}ssbauer measurements.Comment: 4 pages, 2 figures, 2 tables, submitted to PR

Low temperature electronic properties of Sr_2RuO_4 III: Magnetic fields

Based on the microscopic model introduced previously the observed specific heat and ac-susceptibility data in the superconducting phase in Sr_2RuO_4 with applied magnetic fields are described consistently within a phenomenological approach. Discussed in detail are the temperature dependence of the upper critical fields H_{c2} and H_2, the dependence of the upper critical fields on the field direction, the linear specific heat below the superconducting phase transition as a function of field or temperature, the anisotropy of the two spatial components of the order parameter, and the fluctuation field H_p.Comment: 8 pages REVTEX, 4 figure