615 research outputs found
Integrating 'atomistic', intrinsic parameter fluctuations into compact model circuit analysis
MOSFET parameter fluctuations, resulting from the 'atomistic' granular nature of matter, are predicted to be a critical roadblock to the scaling of devices in future electronic systems. A methodology is presented which allows compact model based circuit analysis tools to exploit the results of 'atomistic' device simulation, allowing investigation of the effects of such fluctuations on circuits and systems. The methodology is applied to a CMOS inverter, ring oscillator, and analogue NMOS current mirror as simple initial examples of its efficacy
Why do naked singularities form in gravitational collapse?
We investigate what are the key physical features that cause the development
of a naked singularity, rather than a black hole, as the end-state of spherical
gravitational collapse. We show that sufficiently strong shearing effects near
the singularity delay the formation of the apparent horizon. This exposes the
singularity to an external observer, in contrast to a black hole, which is
hidden behind an event horizon due to the early formation of an apparent
horizon.Comment: revised for clarity, new figure included; version accepted by Phys.
Rev. D (RC
Multicentre double-blind placebo-controlled food challenge study in children sensitised to cashew nut
Background: Few studies with a limited number of patients have provided indications that cashew-allergic patients may experience severe allergic reactions to minimal amounts of cashew nut. The objectives of this multicentre study were to assess the clinical relevance of cashew nut sensitisation, to study the clinical reaction patterns in double-blind placebo-controlled food challenge tests and to establish the amount of cashew nuts that can elicit an allergic reaction. Methods and Findings: A total of 179 children were included (median age 9.0 years; range 2-17 years) with cashew nut sensitisation an
Cross section of the reaction close to threshold
We have measured inclusive data on -meson production in collisions
at COSY J\"ulich close to the hyperon production threshold and determined the
hyperon-nucleon invariant mass spectra. The spectra were decomposed into three
parts: , and . The cross section for the
channel was found to be much smaller than a previous measurement in
that excess energy region. The data together with previous results at higher
energies are compatible with a phase space dependence.Comment: accepted by Phys. lett. B some typos correcte
Detailed comparison of the pp -> \pi^+pn and pp -> \pi^+d reactions at 951 MeV
The positively charged pions produced in proton-proton collisions at a beam
momentum of 1640 MeV/c were measured in the forward direction with a high
resolution magnetic spectrograph. The missing mass distribution shows the bound
state (deuteron) clearly separated from the continuum. Despite the very
good resolution, there is no evidence for any significant production of the
system in the spin-singlet state. However, the cross section ratio is about twice as large as
that predicted from -wave final-state-interaction theory and it is suggested
that this is due to -state effects in the system.Comment: 8 pages, 3 figure
High resolution study of the Lambda p final state interaction in the reaction p + p -> K+ + (Lambda p)
The reaction pp -> K+ + (Lambda p) was measured at Tp=1.953 GeV and Theta = 0
deg with a high missing mass resolution in order to study the Lambda p final
state interaction. The large final state enhancement near the Lambda p
threshold can be described using the standard Jost-function approach. The
singlet and triplet scattering lengths and effective ranges are deduced by
fitting simultaneously the Lambda p invariant mass spectrum and the total cross
section data of the free Lambda p scattering.Comment: submitted to Physics Letters B, 10 pages, 3 figure
Synthesis and characterisation of nanophase hydroxyapatite co-substitutedwith strontium and zinc
Dark Energy and Gravity
I review the problem of dark energy focusing on the cosmological constant as
the candidate and discuss its implications for the nature of gravity. Part 1
briefly overviews the currently popular `concordance cosmology' and summarises
the evidence for dark energy. It also provides the observational and
theoretical arguments in favour of the cosmological constant as the candidate
and emphasises why no other approach really solves the conceptual problems
usually attributed to the cosmological constant. Part 2 describes some of the
approaches to understand the nature of the cosmological constant and attempts
to extract the key ingredients which must be present in any viable solution. I
argue that (i)the cosmological constant problem cannot be satisfactorily solved
until gravitational action is made invariant under the shift of the matter
lagrangian by a constant and (ii) this cannot happen if the metric is the
dynamical variable. Hence the cosmological constant problem essentially has to
do with our (mis)understanding of the nature of gravity. Part 3 discusses an
alternative perspective on gravity in which the action is explicitly invariant
under the above transformation. Extremizing this action leads to an equation
determining the background geometry which gives Einstein's theory at the lowest
order with Lanczos-Lovelock type corrections. (Condensed abstract).Comment: Invited Review for a special Gen.Rel.Grav. issue on Dark Energy,
edited by G.F.R.Ellis, R.Maartens and H.Nicolai; revtex; 22 pages; 2 figure
A precision determination of the mass of the meson
Several processes of meson production in proton-deuteron collisions have been
measured simultaneously using a calibrated magnetic spectrograph. Among these
processes, the meson is seen clearly as a sharp missing--mass peak on a
slowly varying background in the reaction. Knowing
the kinematics of the other reactions with well determined masses, it is
possible to deduce a precise mass for the meson. The final result,
,
is significantly lower than that found by the recent NA48 measurement, though
it is consistent with values obtained in earlier counter experiments.Comment: 10 pages, 6 figures, Fig. 3 change
Trabectedin plus pegylated liposomal doxorubicin in relapsed ovarian cancer delays third-line chemotherapy and prolongs the platinum-free interval
Background: OVA-301 is a large randomized trial that showed superiority of trabectedin plus pegylated liposomal doxorubicin (PLD; CentoCor Ortho Biotech Products L.P., Raritan, NJ, USA). over single-agent PLD in 672 patients with relapsed ovarian cancer, particularly in the partially platinum-sensitive subgroup [platinum-free interval (PFI) of 6–12 months]. This superiority has been suggested to be due to the differential impact of subsequent (platinum) therapy
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