788 research outputs found
Modified conjugated gradient method for diagonalising large matrices
We present an iterative method to diagonalise large matrices. The basic idea
is the same as the conjugated gradient (CG) method, i.e, minimizing the
Rayleigh quotient via its gradient and avoiding reintroduce errors to the
directions of previous gradients. Each iteration step is to find lowest
eigenvector of the matrix in a subspace spanned by the current trial vector and
the corresponding gradient of the Rayleigh quotient, as well as some previous
trial vectors. The gradient, together with the previous trail vectors, play a
similar role of the conjugated gradient of the original CG algorithm. Our
numeric tests indicate that this method converges significantly faster than the
original CG method. And the computational cost of one iteration step is about
the same as the original CG method. It is suitably for first principle
calculations.Comment: 6 Pages, 2EPS figures. (To appear in Phys. Rev. E
Testing SUSY at the LHC: Electroweak and Dark matter fine tuning at two-loop order
In the framework of the Constrained Minimal Supersymmetric Standard Model
(CMSSM) we evaluate the electroweak fine tuning measure that provides a
quantitative test of supersymmetry as a solution to the hierarchy problem.
Taking account of current experimental constraints we compute the fine tuning
at two-loop order and determine the limits on the CMSSM parameter space and the
measurements at the LHC most relevant in covering it. Without imposing the
LEPII bound on the Higgs mass, it is shown that the fine tuning computed at
two-loop has a minimum corresponding to a Higgs mass GeV. Adding the constraint that the SUSY dark matter relic density should be
within present bounds we find corresponding to GeV
and this rises to ( GeV) for SUSY dark matter
abundance within 3 of the WMAP constraint. We extend the analysis to
include the contribution of dark matter fine tuning. In this case the overall
fine tuning and Higgs mass are only marginally larger for the case SUSY dark
matter is subdominant and rises to ( GeV) for
the case of SUSY dark matter saturates the WMAP bound. For a Higgs mass above
these values, fine tuning rises exponentially fast. The CMSSM spectrum that
corresponds to minimal fine tuning is computed and provides a benchmark for
future searches. It is characterised by heavy squarks and sleptons and light
neutralinos, charginos and gluinos.Comment: 36 pages, 24 figure
SO(10) unified models and soft leptogenesis
Motivated by the fact that, in some realistic models combining SO(10) GUTs
and flavour symmetries, it is not possible to achieve the required baryon
asymmetry through the CP asymmetry generated in the decay of right-handed
neutrinos, we take a fresh look on how deep this connection is in SO(10). The
common characteristics of these models are that they use the see-saw with
right-handed neutrinos, predict a normal hierarchy of masses for the neutrinos
observed in oscillating experiments and in the basis where the right-handed
Majorana mass is diagonal, the charged lepton mixings are tiny.
In addition these models link the up-quark Yukawa matrix to the neutrino
Yukawa matrix Y^\nu with the special feature of Y^\nu_{11}-> 0 Using this
condition, we find that the required baryon asymmetry of the Universe can be
explained by the soft leptogenesis using the soft B parameter of the second
lightest right-handed neutrino whose mass turns out to be around 10^8 GeV. It
is pointed out that a natural way to do so is to use no-scale supergravity
where the value of B ~1 GeV is set through gauge-loop corrections.Comment: 26 pages, 2 figures. Added references, new appendix of a relevant fit
and improved comment
Physical restraint in residential child care : the experiences of young people and residential workers
There have long been concerns about the use of physical restraint in residential care. This paper presents the findings of a qualitative study which explores the experiences of children, young people and residential workers about physical restraint. The research identifies the dilemmas and ambiguities for both staff and young people, and participants discuss the situations where they feel physical restraint is appropriate as well as their concerns about unjustified or painful restraints. They describe the negative emotions involved in restraint but also those situations where, through positive relationships and trust, restraint can help young people through unsafe situations
Growth of (110) Diamond using pure Dicarbon
We use a density-functional based tight-binding method to study diamond
growth steps by depositing dicarbon species onto a hydrogen-free diamond (110)
surface. Subsequent C_2 molecules are deposited on an initially clean surface,
in the vicinity of a growing adsorbate cluster, and finally, near vacancies
just before completion of a full new monolayer. The preferred growth stages
arise from C_2n clusters in near ideal lattice positions forming zigzag chains
running along the [-110] direction parallel to the surface. The adsorption
energies are consistently exothermic by 8--10 eV per C_2, depending on the size
of the cluster. The deposition barriers for these processes are in the range of
0.0--0.6 eV. For deposition sites above C_2n clusters the adsorption energies
are smaller by 3 eV, but diffusion to more stable positions is feasible. We
also perform simulations of the diffusion of C_2 molecules on the surface in
the vicinity of existing adsorbate clusters using an augmented Lagrangian
penalty method. We find migration barriers in excess of 3 eV on the clean
surface, and 0.6--1.0 eV on top of graphene-like adsorbates. The barrier
heights and pathways indicate that the growth from gaseous dicarbons proceeds
either by direct adsorption onto clean sites or after migration on top of the
existing C_2n chains.Comment: 8 Pages, 7 figure
Gas-liquid transition in the model of particles interacting at high energy
An application of the ideas of the inertial confinement fusion process in the
case of particles interacting at high energy is investigated. A possibility of
the gas-liquid transition in the gas is considered using different approaches.
In particular, a shock wave description of interactions between particles is
studied and a self-similar solution of Euler's equation is discussed.
Additionally, Boltzmann equation is solved for self-consistent field (Vlasov's
equation) in linear approximation for the case of a gas under external pressure
and the corresponding change of Knudsen number of the system is calculated.Comment: 24 pages, 2 figur
Efficient photoionization for barium ion trapping using a dipole-allowed resonant two-photon transition
Two efficient and isotope-selective resonant two-photon ionization techniques
for loading barium ions into radio-frequency (RF)-traps are demonstrated. The
scheme of using a strong dipole-allowed transition at \lambda=553 nm as a first
step towards ionization is compared to the established technique of using a
weak intercombination line (\lambda=413 nm). An increase of two orders of
magnitude in the ionization efficiency is found favoring the transition at 553
nm. This technique can be implemented using commercial all-solid-state laser
systems and is expected to be advantageous compared to other narrowband
photoionization schemes of barium in cases where highest efficiency and
isotope-selectivity are required.Comment: 8 pages, 5 figure
Exposure to the antimicrobial peptide LL-37 produces dendritic cells optimized for immunotherapy
Immunization of patients with autologous, ex vivo matured dendritic cell (DC) preparations, in order to prime antitumor T-cell responses, is the focus of intense research. Despite progress and approval of clinical approaches, significant enhancement of these personalized immunotherapies is urgently needed to improve efficacy. We show that immunotherapeutic murine and human DC, generated in the presence of the antimicrobial host defense peptide LL-37, have dramatically enhanced expansion and differentiation of cells with key features of the critical CD103 + /CD141 + DC subsets, including enhanced cross-presentation and co-stimulatory capacity, and upregulation of CCR7 with improved migratory capacity. These LL-37-DC enhanced proliferation, activation and cytokine production by CD8 + (but not CD4 + ) T cells in vitro and in vivo. Critically, tumor antigen-presenting LL-37-DC increased migration of primed, activated CD8 + T cells into established squamous cell carcinomas in mice, and resulted in tumor regression. This advance therefore has the potential to dramatically enhance DC immunotherapy protocols
Symptomatic Sinus Node Disease: Natural History After Permanent Ventricular Pacing *
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75403/1/j.1540-8159.1979.tb03650.x.pd
Solution of the Atmospheric Diffusion Equation with Longitudinal Wind Speed Depending on Source Distance
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