1,053 research outputs found
Real-time three-dimensional ultrasound : a valuable new tool in preoperative assessment of complex congenital cardiac disease
Evaluating complex cardiac defects in small children preoperatively requires multiple diagnostic procedures including echocardiography, and also invasive methods such as cardiac catheterisation, computer-tomography and magnetic resonance imaging. This article assesses the complex anatomy of the atrioventricular valves in atrioventricular septal defect using bedside real-time three-dimensional echocardiography and comparing these results to the anatomic findings at the time of operative intervention.peer-reviewe
See-Saw Masses for Quarks and Leptons in SU(5)
We build on a recent paper by Grinstein, Redi and Villadoro, where a see-saw
like mechanism for quark masses was derived in the context of spontaneously
broken gauged flavour symmetries. The see-saw mechanism is induced by heavy
Dirac fermions which are added to the Standard Model spectrum in order to
render the flavour symmetries anomaly-free. In this letter we report on the
embedding of these fermions into multiplets of an SU(5) grand unified theory
and discuss a number of interesting consequences.Comment: 15 pages, 4 figures (v3: outline restructured, modified mechanism to
cancel anomalies
The fate of high redshift massive compact galaxies in dense environments
Massive compact galaxies seem to be more common at high redshift than in the
local universe, especially in denser environments. To investigate the fate of
such massive galaxies identified at z~2 we analyse the evolution of their
properties in three cosmological hydrodynamical simulations that form
virialised galaxy groups of mass ~10^13 Msun hosting a central massive
elliptical/S0 galaxy by redshift zero. We find that at redshift ~2 the
population of galaxies with M_*> 2 10^10 Msun is diverse in terms of mass,
velocity dispersion, star formation and effective radius, containing both very
compact and relatively extended objects. In each simulation all the compact
satellite galaxies have merged into the central galaxy by redshift 0 (with the
exception of one simulation where one of such satellite galaxy survives).
Satellites of similar mass at z = 0 are all less compact than their high
redshift counterparts. They form later than the galaxies in the z = 2 sample
and enter the group potential at z < 1, when dynamical friction times are
longer than the Hubble time. Also, by z = 0 the central galaxies have increased
substantially their characteristic radius via a combination of in situ star
formation and mergers. Hence in a group environment descendants of compact
galaxies either evolve towards larger sizes or they disappear before the
present time as a result of the environment in which they evolve. Since the
group-sized halos that we consider are representative of dense environments in
the LambdaCDM cosmology, we conclude that the majority of high redshift compact
massive galaxies do not survive until today as a result of the environment.Comment: 10 pages, 4 figures, submitted to MNRA
Lepton polarization in Decays
We study the single and double lepton polarization asymmetries in the
semileptonic meson decays ,
, ), where the strange -wave meson, , is the mixtures
of the and , which are the and states,
respectively. The lepton polarization asymmetries show relatively strong
dependency in the various region of dileptonic invariant mass. The lepton
polarization asymmetries can also be used for determining the
-- mixing angle, and new physics effects.
Furthermore, it is shown that these asymmetries in
decay compared with those of decay are more sensitive to
the dileptonic invariant mass
Optically induced damping of the surface plasmon resonance in gold colloids
The surface plasmon damping induced by high excitation of the electron gas is studied in femtosecond pump-and-probe experiments on gold colloids embedded in a sol-gel matrix. Optical excitation of single-particle interband transitions leads to a pronounced broadening of the surface plasmon line. A similar behavior is observed for resonant excitation of the surface plasmon. This broadening is the dominant optical nonlinearity of the system, and reflects the excitation-induced damping of the surface plasmon resonance. The time evolution of the damping rate follows that of the electronic scattering rate
Chaotic Free-Space Laser Communication over Turbulent Channel
The dynamics of errors caused by atmospheric turbulence in a
self-synchronizing chaos based communication system that stably transmits
information over a 5 km free-space laser link is studied experimentally.
Binary information is transmitted using a chaotic sequence of short-term pulses
as carrier. The information signal slightly shifts the chaotic time position of
each pulse depending on the information bit. We report the results of an
experimental analysis of the atmospheric turbulence in the channel and the
impact of turbulence on the Bit-Error-Rate (BER) performance of this chaos
based communication system.Comment: 4 pages, 5 figure
Elucidation of the Cellular Interactome of Ebola Virus Nucleoprotein and Identification of Therapeutic Targets
Ebola virus (EBOV) infection results in severe disease and in some cases lethal haemorrhagic fever. The infection is directed by seven viral genes that encode nine viral proteins. By definition viruses are obligate intracellular parasites and require aspects of host cell biology in order to replicate their genetic material, assemble new virus particles and subvert host cell anti-viral responses. Currently licenced antivirals are targeted against viral proteins to inhibit their function. However, experience with treating HIV and influenza virus demonstrates that resistant viruses are soon selected. An emerging area in virology is to transiently target host cell proteins that play critical proviral roles in virus biology, especially for acute infections. This has the advantage that the protein being targeted is evolutionary removed from the genome of the virus. Proteomics can aid in discovery biology and identify cellular proteins that may be utilised by the virus to facilitate infection. This work focused on defining the interactome of the EBOV nucleoprotein and identified that cellular chaperones, including HSP70, associate with this protein to promote stability. Utilisation of a mini-genome replication system based on a recent Makona isolate demonstrated that disrupting the stability of NP had an adverse effect on viral RNA synthesis
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