1,398 research outputs found
h\to \gamma \gamma In Inert Higgs Doublet Model
Motivated by the recent result reported from LHC on the di-photon search for
a Standard Model (SM) Higgs-like boson. We discuss the implications of this
possible signal in the framework of the Inert Higgs Doublet Model (IHDM),
taking into account previous limits from Higgs searches at LEP, the Tevatron
and the LHC as well as constraints from unitarity, vacuum stability and
electroweak precision tests. We show that the charged Higgs contributions can
interfere constructively or destructively with the W gauge bosons loops leading
to enhancement or suppression of the di-photon rate with respect to SM rate. We
show also that the invisible decay of the Higgs, if open, could affect the
total width of the SM Higgs boson and therefore suppress the di-photon rate.Comment: 15 pages, added reference
A Spallation Model for the Titanium-rich Supernova Remnant Cassiopeia A
Titanium-rich subluminous supernovae are rare and challenge current SN
nucleosynthesis models. We present a model in which ejecta from a standard
Supernova is impacted by a second explosion of the neutron star (a Quark-nova),
resulting in spallation reactions that lead to 56Ni destruction and 44Ti
creation under the right conditions. Basic calculations of the spallation
products shows that a delay between the two explosions of ~ 5 days reproduces
the observed abundance of 44Ti in Cas A and explains its low luminosity as a
result of the destruction of 56Ni. Our results could have important
implications for lightcurves of subluminous as well as superluminous
supernovae.Comment: Accepted/to be published in Physical Review Letters. [ for more info
on the Quark Nova, see: http://quarknova.ucalgary.ca/
Enhancement of chemotherapy using oncolytic virotherapy: Mathematical and optimal control analysis
Oncolytic virotherapy (OV) has been emerging as a promising novel cancer
treatment that may be further combined with the existing therapeutic modalities
to enhance their effects. To investigate how OV could enhance chemotherapy, we
propose an ODE based model describing the interactions between tumour cells,
the immune response, and a treatment combination with chemotherapy and
oncolytic viruses. Stability analysis of the model with constant chemotherapy
treatment rates shows that without any form of treatment, a tumour would grow
to its maximum size. It also demonstrates that chemotherapy alone is capable of
clearing tumour cells provided that the drug efficacy is greater than the
intrinsic tumour growth rate. Furthermore, OV alone may not be able to clear
tumour cells from body tissue but would rather enhance chemotherapy if viruses
with high viral potency are used. To assess the combined effect of OV and
chemotherapy we use the forward sensitivity index to perform a sensitivity
analysis, with respect to chemotherapy key parameters, of the virus basic
reproductive number and the tumour endemic equilibrium. The results from this
sensitivity analysis indicate the existence of a critical dose of chemotherapy
above which no further significant reduction in the tumour population can be
observed. Numerical simulations show that a successful combinational therapy of
the chemotherapeutic drugs and viruses depends mostly on the virus burst size,
infection rate, and the amount of drugs supplied. Optimal control analysis was
performed, by means of Pontryagin's principle, to further refine predictions of
the model with constant treatment rates by accounting for the treatment costs
and sides effects.Comment: This is a preprint of a paper whose final and definite form is with
'Mathematical Biosciences and Engineering', ISSN 1551-0018 (print), ISSN
1547-1063 (online), available at
[http://www.aimsciences.org/journal/1551-0018]. Submitted 27-March-2018;
revised 04-July-2018; accepted for publication 10-July-201
Quark deconfinement in neutron star cores: The effects of spin-down
We study the role of spin-down in driving quark deconfinement in the high
density core of isolated neutron stars. Assuming spin-down to be solely due to
magnetic braking, we obtain typical timescales to quark deconfinement for
neutron stars that are born with Keplerian frequencies. Employing different
equations of state (EOS), we determine the minimum and maximum neutron star
masses that will allow for deconfinement via spin-down only. We find that the
time to reach deconfinement is strongly dependent on the magnetic field and
that this time is least for EOS that support the largest minimum mass at zero
spin, unless rotational effects on stellar structure are large. For a fiducial
critical density of for the transition to the quark phase
(g/cm is the saturation density of nuclear
matter), we find that neutron stars lighter than cannot reach a
deconfined phase. Depending on the EOS, neutron stars of more than
can enter a quark phase only if they are spinning faster than
about 3 milliseconds as observed now, whereas larger spin periods imply that
they are either already quark stars or will never become one.Comment: 4 pages, 4 figures, submitted to ApJ
Effect of tillage practices on the soil carbon dioxide flux during fall and spring seasons in a Mediterranean Vertisol
In this study, we assessed the effect of conventional tillage (CT), reduced (RT) and no tillage (NT) practices on the soil CO2 flux of a Mediterranean Vertisol in semi-arid Morocco. The measurements focused on the short term (0 to 96 h) soil CO2 fluxes measured directly after tillage during the fall and spring period. Soil temperature, moisture and soil strength were measured congruently to study their effect on the soil CO2 flux magnitude. Immediately after fall tillage, the CT showed the highest CO2 flux (4.9 g m-2 h-1); RT exhibited an intermediate value (2.1 g m-2 h-1) whereas the lowest flux (0.7 g m-2 h-1) was reported under NT. After spring tillage, similar but smaller impacts of the tillage practices on soil CO2 flux were reported with fluxes ranging from 1.8 g CO2 m-2 h-1 (CT) to less than 0.1 g CO2 m-2 h-1 (NT). Soil strength was significantly correlated with soil CO2 emission; whereas surface soil temperature and moisture were low correlated to the soil CO2 flux. The intensity of rainfall events before fall and spring tillage practices could explain the seasonal CO2 flux trends. The findings promote conservation tillage and more specifically no tillage practices to reduce CO2 losses within these Mediterranean agroecosystems. (Résumé d'auteur
Process Identification through Test on Cryogenic System
UNICOS (UNified Industrial Control System) is the CERN object-based control standard for the cryogenics of the LHC and its experiments. It includes a variety of embedded functions, dedicated to the specific cryogenic processes. To enlarge the capabilities of the standard it is proposed to integrate the parametrical identification step in the control system of large scale cryogenic plants. Different methods of parametrical identification have been tested and the results were combined to obtain a better model. The main objective of the work is to find a compromise between an easy-to-use solution and a good level of process identification model. The study focuses on identification protocol for large delayed system, the measurement consistency and correlation between different inputs and outputs. Furthermore the paper describes in details, the results and the tests carried out on parametrical identification investigations with large scale systems
State-of-the-Art Management of Complications of Myeloma and Its Treatment
Multiple myeloma is an incurable disease, although patient survival has increased with the availability of novel agents. Both multiple myeloma and its therapies often affect the renal, immune, skeletal, hematologic, and nervous systems. The resulting organ dysfunctions often impair the quality of life of affected patients, complicate and limit subsequent therapies, and may result in significant mortality. Research on the treatment of complications of multiple myeloma has been limited; hence, preventative and management strategies for patients with these complications are heterogeneous and often based on anecdotal experience. In this paper, we review the effects of myeloma and the novel therapies on organ systems and suggest management strategies
Periodic Structures with Rashba Interaction in Magnetic Field
We analyze the behaviour of a system of particles living on a periodic
crystal in the presence of a magnetic field B. This can be done by involving a
periodic potential U(x) and the Rashba interaction of coupling constant k_{so}.
By resorting the corresponding spectrum, we explicitly determine the band
structures and the Bloch spinors. These allow us to discuss the system
symmetries in terms of the polarizations where they are shown to be broken. The
dynamical spin will be studied by calculating different quantities. In the
limits: k_{so} and U(x)=0, we analyze again the system by deriving different
results. Considering the strong case, we obtain an interesting result that
is the conservation of the polarizations. Analyzing the critical point
\lambda_{k,\sigma}=\pm\sq{1\over 2}, we show that the Hilbert space associated
to the spectrum in z-direction has a zero mode energy similar to that of
massless Dirac fermions in graphene. Finally, we give the resulting energy
spectrum when B=0 and U(x) is arbitrary.Comment: 24 pages, references added, misprints corrected. Version to appear in
JP
On F-theory Quiver Models and Kac-Moody Algebras
We discuss quiver gauge models with bi-fundamental and fundamental matter
obtained from F-theory compactified on ALE spaces over a four dimensional base
space. We focus on the base geometry which consists of intersecting F0=CP1xCP1
Hirzebruch complex surfaces arranged as Dynkin graphs classified by three kinds
of Kac-Moody (KM) algebras: ordinary, i.e finite dimensional, affine and
indefinite, in particular hyperbolic. We interpret the equations defining these
three classes of generalized Lie algebras as the anomaly cancelation condition
of the corresponding N =1 F-theory quivers in four dimensions. We analyze in
some detail hyperbolic geometries obtained from the affine A base geometry by
adding a node, and we find that it can be used to incorporate fundamental
fields to a product of SU-type gauge groups and fields.Comment: 13 pages; new equations added in section 3, one reference added and
typos correcte
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