17,568 research outputs found
FPGA Architecture Optimization Using Geometric Programming
Volume 4 No 13 of the periodical Progression. Published November, February, May and August by The Radiant Healing Centre. SPCL PER BT 732 P76 V.1,1932-V.5,193
A novel heuristic and provable bounds for reconfigurable architecture design
Published versio
Transport spectroscopy of an impurity spin in a carbon nanotube double quantum dot.
We make use of spin selection rules to investigate the electron spin system of a carbon nanotube double quantum dot. Measurements of the electron transport as a function of the magnetic field and energy detuning between the quantum dots reveal an intricate pattern of the spin state evolution. We demonstrate that the complete set of measurements can be understood by taking into account the interplay between spin-orbit interaction and a single impurity spin coupled to the double dot. The detection and tunability of this coupling are important for quantum manipulation in carbon nanotubes
Embryonic Development and a Quantitative Model of Programmed DNA Elimination in Mesocyclops Edax (S. A. ) (Copepoda: Cyclopoida)
The highly programmed fragmentation of chromosomes and elimination of large amounts of nuclear DNA from the presomatic cell lineages (i.e., chromatin diminution), occurs in the embryos of the freshwater zooplankton Mesocyclops edax (S. A. Forbes, 1891) (Crustacea: Copepoda). The somatic genome is reorganized and reduced to a size five times smaller even though the germline genome remains intact. We present the first comprehensive, quantitative model of DNA content throughout embryogenesis in a copepod that possesses embryonic DNA elimination. We used densitometric image analysis to measure the DNA content of polar bodies, germline and somatic nuclei, and excised DNA “droplets.” We report: 1) variable DNA contents of polar bodies, some of which do not contain the amount corresponding to the haploid germline genome size; 2) presence of pronuclei in newly laid embryo sacs; 3) gonomeric chromosomes in the second to fourth cleavage divisions and in the primordial germ cell and primordial endoderm cell during the fifth cleavage division; 4) timing of early embryonic cell stages, elimination of DNA, and divisions of the primordial germ cell and primordial endoderm cell at 22∘C role= presentation \u3e22∘C; and 5) persistence of a portion of the excised DNA “droplets” throughout embryogenesis. DNA elimination is a trait that spans multiple embryonic stages and a knowledge of the timing and variability of the associated cytological events with DNA elimination will promote the study of the molecular mechanisms involved in this trait. We propose the “genome yolk hypothesis” as a functional explanation for the persistence of the eliminated DNA that might serve as a resource during postdiminution cleavage divisions
Large-Scale Structures Behind the Milky Way from Near-IR Surveys
About 25% of the optical extragalactic sky is obscured by the dust and stars
of our Milky Way. Dynamically important structures might still lie hidden in
this zone. Various approaches are presently being employed to uncover the
galaxy distribution in the Zone of Avoidance (ZOA) but all suffer from
(different) limitations and selection effects.
We investigated the potential of using the DENIS NIR survey for studies of
galaxies behind the obscuration layer of our Milky Way and for mapping the
Galactic extinction. As a pilot study, we recovered DENIS I, J and K band
images of heavily obscured but optically still visible galaxies. We determined
the I, J and K band luminosity functions of galaxies on three DENIS strips that
cross the center of the nearby, low-latitude, rich cluster Abell 3627. The
extinction-corrected I-J and J-K colours of these cluster galaxies compare well
with that of an unobscured cluster. We searched for and identified galaxies at
latitudes where the Milky Way remains fully opaque (|b|
4-5mag) - in a systematic search as well as around positions of galaxies
detected with the blind HI survey of the ZOA currently conducted with the
Multibeam Receiver of the Parkes Radiotelescope.Comment: 12 pages, including 5 PS figures, LaTeX, uses crckapb.sty and
epsf.tex. Better resolved figures available upon request. To appear in
proceedings of the 3rd Euroconference (Meudon, France, June 1997) on ``The
Impact of Near IR Surveys'', Kluwer 199
Breakthrough Seizures - Further analysis of the Standard versus New Antiepileptic Drugs (SANAD) study
Objectives To develop prognostic models for risk of a breakthrough seizure, risk of seizure recurrence after a breakthrough seizure, and likelihood of achieving 12-month remission following a breakthrough seizure. A breakthrough seizure is one that occurs following at least 12 months remission whilst on treatment. Methods We analysed data from the SANAD study. This long-term randomised trial compared treatments for participants with newly diagnosed epilepsy. Multivariable Cox models investigated how clinical factors affect the probability of each outcome. Best fitting multivariable models were produced with variable reduction by Akaike’s Information Criterion. Risks associated with combinations of risk factors were calculated from each multivariable model. Results Significant factors in the multivariable model for risk of a breakthrough seizure following 12-month remission were number of tonic-clonic seizures by achievement of 12-month remission, time taken to achieve 12-month remission, and neurological insult. Significant factors in the model for risk of seizure recurrence following a breakthrough seizure were total number of drugs attempted to achieve 12-month remission, time to achieve 12-month remission prior to breakthrough seizure, and breakthrough seizure treatment decision. Significant factors in the model for likelihood of achieving 12-month remission after a breakthrough seizure were gender, age at breakthrough seizure, time to achieve 12-month remission prior to breakthrough, and breakthrough seizure treatment decision. Conclusions This is the first analysis to consider risk of a breakthrough seizure and subsequent outcomes. The described models can be used to identify people most likely to have a breakthrough seizure, a seizure recurrence following a breakthrough seizure, and to achieve 12-month remission following a breakthrough seizure. The results suggest that focussing on achieving 12-month remission swiftly represents the best therapeutic aim to reduce the risk of a breakthrough seizure and subsequent negative outcomes. This will aid individual patient risk stratification and the design of future epilepsy trials
What is the optimal management of partial epilepsy uncontrolled by a first choice anticonvulsant?
A unique dual activity amino acid hydroxylase in Toxoplasma gondii
The genome of the protozoan parasite Toxoplasma gondii was found to contain two genes encoding tyrosine hydroxylase; that produces L-DOPA. The encoded enzymes metabolize phenylalanine as well as tyrosine with substrate preference for tyrosine. Thus the enzymes catabolize phenylalanine to tyrosine and tyrosine to L-DOPA. The catalytic domain descriptive of this class of enzymes is conserved with the parasite enzyme and exhibits similar kinetic properties to metazoan tyrosine hydroxylases, but contains a unique N-terminal extension with a signal sequence motif. One of the genes, TgAaaH1, is constitutively expressed while the other gene, TgAaaH2, is induced during formation of the bradyzoites of the cyst stages of the life cycle. This is the first description of an aromatic amino acid hydroxylase in an apicomplexan parasite. Extensive searching of apicomplexan genome sequences revealed an ortholog in Neospora caninum but not in Eimeria, Cryptosporidium, Theileria, or Plasmodium. Possible role(s) of these bi-functional enzymes during host infection are discussed. © 2009 Gaskell et al
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