47,860 research outputs found
A Functional Architecture Approach to Neural Systems
The technology for the design of systems to perform extremely complex combinations of real-time functionality has developed over a long period. This technology is based on the use of a hardware architecture with a physical separation into memory and processing, and a software architecture which divides functionality into a disciplined hierarchy of software components which exchange unambiguous information. This technology experiences difficulty in design of systems to perform parallel processing, and extreme difficulty in design of systems which can heuristically change their own functionality. These limitations derive from the approach to information exchange between functional components. A design approach in which functional components can exchange ambiguous information leads to systems with the recommendation architecture which are less subject to these limitations. Biological brains have been constrained by natural pressures to adopt functional architectures with this different information exchange approach. Neural networks have not made a complete shift to use of ambiguous information, and do not address adequate management of context for ambiguous information exchange between modules. As a result such networks cannot be scaled to complex functionality. Simulations of systems with the recommendation architecture demonstrate the capability to heuristically organize to perform complex functionality
Electroweak and CP violation physics at a Linear Collider Z-factory
A future linear collider such as TESLA may be able to run on the Z0 resonance
with very high luminosity and polarised electron and positron beams. The
possibilities of measuring electroweak quantities with high precision are
investigated. Huge improvements with respect to the present precision can be
expected, especially for the asymmetries A_LR and A_b where beam polarisation
can be exploited. The very large sample of Z to bbbar events also allows
studies of various CP-violating b decays. The precision achievable on the CKM
unitarity triangle angles is comparable to experiments at b factories and
future hadron colliders.Comment: 26 pages, 11 figures. To be submitted to European Journal of Physics
Direc
Constraints on neutrino masses from a Galactic supernova neutrino signal at present and future detectors
We study the constraints on neutrino masses that could be derived from the
observation of a Galactic supernova neutrino signal with present and future
neutrino detectors. Our analysis is based on a recently proposed method that
uses the full statistics of neutrino events and does not depend on particular
astrophysical assumptions. The statistical approach, originally justified
mainly in terms of intuitive reasoning, is put on a more solid basis by means
of Bayesian inference reasoning. Theoretical uncertainties in the neutrino
signal time profiles are estimated by applying the method to two widely
different supernova models. Present detectors can reach a sensitivity down to 1
eV. This is better than limits from tritium -decay experiments,
competitive with the most conservative results from neutrinoless double
-decay, less precise but less dependent from prior assumptions than
cosmological bounds. Future megaton water Cerencov detectors will allow for
about a factor of two improvement. However, they will not be competitive with
the next generation of laboratory experiments.Comment: 28 pages, 5 Figures, added discussion on systematic errors and some
clarifications. Results unchanged. Published versio
Fatty-acid uptake in prostate cancer cells using dynamic microfluidic raman technology
It is known that intake of dietary fatty acid (FA) is strongly correlated with prostate cancer progression but is highly dependent on the type of FAs. High levels of palmitic acid (PA) or arachidonic acid (AA) can stimulate the progression of cancer. In this study, a unique experimental set-up consisting of a Raman microscope, coupled with a commercial shear-flow microfluidic system is used to monitor fatty acid uptake by prostate cancer (PC-3) cells in real-time at the single cell level. Uptake of deuterated PA, deuterated AA, and the omega-3 fatty acids docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) were monitored using this new system, while complementary flow cytometry experiments using Nile red staining, were also conducted for the validation of the cellular lipid uptake. Using this novel experimental system, we show that DHA and EPA have inhibitory effects on the uptake of PA and AA by PC-3 cells
Standard Model tests with trapped radioactive atoms
We review the use of laser cooling and trapping for Standard Model tests,
focusing on trapping of radioactive isotopes. Experiments with neutral atoms
trapped with modern laser cooling techniques are testing several basic
predictions of electroweak unification. For nuclear decay, demonstrated
trap techniques include neutrino momentum measurements from beta-recoil
coincidences, along with methods to produce highly polarized samples. These
techniques have set the best general constraints on non-Standard Model scalar
interactions in the first generation of particles. They also have the promise
to test whether parity symmetry is maximally violated, to search for tensor
interactions, and to search for new sources of time reversal violation. There
are also possibilites for exotic particle searches. Measurements of the
strength of the weak neutral current can be assisted by precision atomic
experiments using traps of small numbers of radioactive atoms, and sensitivity
to possible time-reversal violating electric dipole moments can be improved.Comment: 45 pages, 17 figures, v3 includes clarifying referee comments,
especially in beta decay section, and updated figure
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