MOSAIC: An integrated ultrasonic 2-D array system

An investigation into the development of an ultrasound imaging system capable of customization for multiple applications via the tessellation of in-system programmable scalable modules, or tiles, is presented here. Each tile contains an individual ultrasonic array, operating at +/-3.3V, which can be assembled into a larger ‘mosaic’ of multiple tiles to create arrays of any size or shape. The ability to form an imaging system from generic building blocks which are physically identical for manufacturing purposes yet functionally unique via programming to suit the application has many potential benefits in the field of ultrasonics. The system is primarily targeted at underwater sonar and non-destructive testing, as defined by the current excitation frequency, but the concept is equally applicable to applications in biomedical ultrasound

A modular FPGA-based ultrasonic array system for applications including non-destructive testing

This paper reports work aimed at the development of an ultrasonic imaging system comprising modular, reprogrammable building blocks, or tiles, which can be customised for multiple applications, including and within non-destructive testing (NDT), by the user. The key component is an autonomous module containing the ultrasonic array and all the electronics necessary to operate it. This contrasts with most previous research on system integration which has focused only on the transducer and front-end electronics.<p></p> In the present work, a 4 4 element 2D piezoelectric array with a 16 mm 16 mm aperture has been produced, with the entire transmission and reception electronics within the same footprint. The proximity of the transducer array and electronics removes the need for cabling, reducing signal degradation due to cross talk and interference. In addition, it avoids the problem of electrical impedance matching of cable between the array elements and the electronics. <p></p> Pulse-echo insertion loss of 48 dB has been measured from back-wall reflections in 73 mm-thick aluminium without decoding, and results with decoded signals show adequate signal-to-noise ratio (SNR) with 3.3 V excitation at an operating frequency of 1.2 MHz, within the range required for deep penetration in nuclear power plant. <p></p> Crucially, the ability to construct 2D arrays of any size and shape from generic building blocks represents a departure from almost all previous work in ultrasound, which has traditionally been highly application specific. This may allow ultrasonic NDT to be used in applications for which the investment in customised devices could not previously be justified. <p></p&gt

An evaluation of immunohistochemistry for studying cyclic nucleotides in the central nervous system, with particular reference to guanosine 3',5'-monophosphate

An immunofluorescent technique has been developed with the aim of histochemically localizing cyclic AMP and cyclic GMP in the C.N.S., and determining the cellular sites where biochemical changes in tissue levels occur.Initial experiments revealed that the inmunoglobulin fraction of non -immune sera bound non -specifically to C.N.S. tissue, via a weak charge attachment between IgG and basic tissue proteins.Specific antibodies were raised in rabbits by immunization with succinyl cyclic nucleotide- protein conjugates, and radioiunological techniques with[3H]tracers were used to study binding characteristics. Of the large number of cyclic GMP antibodies studied in detail, specific staining of astrocytic fibres and capillaries (a contrasting localization to that of cyclic AMP), was found with only a small number of antibodies, although these could not be identified on the basis of titre, avidity or specificity however.Differences between RIA and immunohistochemistry, and different staining patterns with individual cyclic GMP antibodies, have been discussed as resulting from stereochemical differences between free and tissue -bound nucleotide. This may also explain why cyclic nucleotide antibodies have satisfied the criteria of specificity for RIA, but not for immunofluorescence.'In vivo' and 'in vitro' biochemical techniques, coupled with cyclic GMP immunofluorescence, failed to localize semi -quantitative changes in intensity and /or distribution of staining, under conditions where total nucleotide levels were significantly altered. - iv - Quantifying cyclic nucleotide losses from frozen tissue sections, it was determined that more than 80% of cyclic GMP was lost during buffer -washing, and that the tissue -bound pool was unchanged when total levels were elevated - a possible explanation for the inability to localize biochemical changes using i mm nofluorescence.Quantifying cyclic nucleotide losses from frozen tissue sections, it was determined that more than 80% of cyclic GMP was lost during buffer -washing, and that the tissue -bound pool was unchanged when total levels were elevated - a possible explanation for the inability to localize biochemical changes using immnofluorescence.Recently developed antibodies to cyclic GMP- dependent protein kinase, and other cyclic nucleotide receptor proteins, were used to investigate the binding, and determine the function of, the pool of cyclic nucleotides localized in C.N.S. tissue sections by immunofluorescence

Deep crustal heating by neutrinos from the surface of accreting neutron stars

We present a new mechanism for deep crustal heating in accreting neutron stars. Charged pions ($\pi^+$) are produced in nuclear collisions on the neutron star surface during active accretion and upon decay they provide a flux of neutrinos into the neutron star crust. For massive and/or compact neutron stars, neutrinos deposit $\approx 1\textrm{--} 2 \, \mathrm{MeV}$ of heat per accreted nucleon into the inner crust. The strength of neutrino heating is comparable to the previously known sources of deep crustal heating, such as from pycnonuclear fusion reactions, and is relevant for studies of cooling neutron stars. We model the thermal evolution of a transient neutron star in a low-mass X-ray binary, and in the particular case of the neutron star MXB~1659-29 we show that additional deep crustal heating requires a higher thermal conductivity for the neutron star inner crust. A better knowledge of pion production cross sections near threshold would improve the accuracy of our predictions.Comment: 12 pages, 9 figures, 3 tables; [Added a new figure and edited the text in response to Referee's remarks and suggestions

Listening Talk. An experience of academic-practitioner dialogue in Bradford district: Second systematisation of learning (2007-2012)

YesIn human societies there will always be differences of views and interests. But the reality today is that we are all interdependent and have to coexist on this small planet. Therefore, the only sensible and intelligent way of resolving differences and clashes of interests, whether between individuals or nations, is through dialogue. The promotion of a culture of dialogue and nonviolence for the future of mankind is thus an important task of the international community. (His Holiness the Dalai Lama, in a speech to the “Forum 2000″ Conference, Prague, Czech Republic, September 4, 1997