220 research outputs found
Strange Particle Production Via The Weak Interaction
The differential cross sections for the neutrino-induced weak charged current
production of strange particles in the threshold energy region are presented.
The general representation of the weak hadronic current is newly developed in
terms of eighteen unknown invariant amplitudes to parametrize the hadron
vertex. The Born term approximation is used for the numerical calculations in
the framework of the Cabibbo theory and SU(3) symmetry. For unpolarized octet
baryons four processes are investigated, whereas in the case of polarized
baryons only one process is chosen to study the sensitivity of the differential
cross section to the various polarizations of the initial state nucleon and the
final state hyperon.Comment: This paper was originally submitted to Physical Review C and
published on 30 August, 201
Associated hyperon-kaon production via neutrino-nucleus scattering
We present the investigation of the neutrino-induced strangeness associated
production on nuclei in the relativistic plane wave impulse approximation
(RPWIA) framework at the intermediate neutrino energies. In this study, the
elementary hadronic weak amplitudes are embedded inside the nuclear medium for
the description of the exclusive channels of neutrino-nucleus interactions.
These amplitudes are extracted using a model-dependent evaluation of the
hadronic vertex using the Born term approximation in which the application of
the Cabibbo V-A theory and SU(3) symmetry are assumed to be valid. The nuclear
effects are included via the bound state wavefunctions of the nucleon obtained
from the relativistic mean field (RMF) models. Two kinematics settings are used
to examine various distributions of the differential cross section in the rest
frame of the target nuclei. The numerical results are obtained for the
neutrino-induced charged-current (CC) \,-production on bound
neutrons in and orbitals of C. The angular
distributions are forward peaked under both kinematic settings, whereas under
the quasifree setting the cross sections tend mimic the missing momentum
distribution of the bound nucleon inside the nucleus.Comment: This article is submitted to International Journal of Modern Physics
E (nuclear physics) and accepted on 31 October 20l
Charged kaon production by coherent scattering of neutrinos and antineutrinos on nuclei
With the aim of achieving a better and more complete understanding of
neutrino interactions with nuclear targets, the coherent production of charged
kaons induced by neutrinos and antineutrinos is investigated in the energy
range of some of the current neutrino experiments. We follow a microscopic
approach which, at the nucleon level, incorporates the most important
mechanisms allowed by the chiral symmetry breaking pattern of QCD. The
distortion of the outgoing (anti)kaon is taken into account by solving the
Klein-Gordon equation with realistic optical potentials. Angular and momentum
distributions are studied, as well as the energy and nuclear dependence of the
total cross section.Comment: 20 pages, 14 figure
Spacetime Noncommutativity and Antisymmetric Tensor Dynamics in the Early Universe
This paper investigates the possible cosmological implications of the
presence of an antisymmetric tensor field related to a lack of commutatitivity
of spacetime coordinates at the Planck era. For this purpose, such a field is
promoted to a dynamical variable, inspired by tensor formalism. By working to
quadratic order in the antisymmetric tensor, we study the field equations in a
Bianchi I universe in two models: an antisymmetric tensor plus scalar field
coupled to gravity, or a cosmological constant and a free massless
antisymmetric tensor. In the first scenario, numerical integration shows that,
in the very early universe, the effects of the antisymmetric tensor can prevail
on the scalar field, while at late times the former approaches zero and the
latter drives the isotropization of the universe. In the second model, an
approximate solution is obtained of a nonlinear ordinary differential equation
which shows how the mean Hubble parameter and the difference between
longitudinal and orthogonal Hubble parameter evolve in the early universe.Comment: 25 pages, Revtex file, 4 figures in attachmen
Tunable Thermal Energy Transport across Diamond Membranes and Diamond-Si Interfaces by Nanoscale Graphoepitaxy
The development of electronic devices, especially those that involve
heterogeneous integration of materials, has led to increased challenges in
addressing their thermal operational-temperature demands. The heat flow in
these systems is significantly influenced or even dominated by thermal boundary
resistance at interface between dissimilar materials. However, controlling and
tuning heat transport across an interface and in the adjacent materials has so
far drawn limited attention. In this work, we grow chemical-vapor-deposited
(CVD) diamond on silicon substrates by graphoepitaxy and experimentally
demonstrate tunable thermal transport across diamond membranes and
diamond-silicon interfaces. We observed the highest diamond-silicon thermal
boundary conductance (TBC) measured to date and increased diamond thermal
conductivity due to strong grain texturing in the diamond near the interface.
Additionally, non-equilibrium molecular-dynamics (NEMD) simulations and a
Landauer approach are used to understand the diamond-silicon TBC. These
findings pave the way for tuning or increasing thermal conductance in
heterogeneously integrated electronics that involve polycrystalline materials
and will impact applications including electronics thermal management and
diamond growth
Thyrotropin-releasing hormone (TRH) promotes wound re-epithelialisation in frog and human skin
There remains a critical need for new therapeutics that promote wound healing in patients suffering from chronic skin wounds. This is, in part, due to a shortage of simple, physiologically and clinically relevant test systems for investigating candidate agents. The skin of amphibians possesses a remarkable regenerative capacity, which remains insufficiently explored for clinical purposes. Combining comparative biology with a translational medicine approach, we report the development and application of a simple ex vivo frog (Xenopus tropicalis) skin organ culture system that permits exploration of the effects of amphibian skin-derived agents on re-epithelialisation in both frog and human skin. Using this amphibian model, we identify thyrotropin-releasing hormone (TRH) as a novel stimulant of epidermal regeneration. Moving to a complementary human ex vivo wounded skin assay, we demonstrate that the effects of TRH are conserved across the amphibian-mammalian divide: TRH stimulates wound closure and formation of neo-epidermis in organ-cultured human skin, accompanied by increased keratinocyte proliferation and wound healing-associated differentiation (cytokeratin 6 expression). Thus, TRH represents a novel, clinically relevant neuroendocrine wound repair promoter that deserves further exploration. These complementary frog and human skin ex vivo assays encourage a comparative biology approach in future wound healing research so as to facilitate the rapid identification and preclinical testing of novel, evolutionarily conserved, and clinically relevant wound healing promoters
Exciton swapping in a twisted graphene bilayer as a solid-state realization of a two-brane model
It is shown that exciton swapping between two graphene sheets may occur under
specific conditions. A magnetically tunable optical filter is described to
demonstrate this new effect. Mathematically, it is shown that two turbostratic
graphene layers can be described as a "noncommutative" two-sheeted
(2+1)-spacetime thanks to a formalism previously introduced for the study of
braneworlds in high energy physics. The Hamiltonian of the model contains a
coupling term connecting the two layers which is similar to the coupling
existing between two braneworlds at a quantum level. In the present case, this
term is related to a K-K' intervalley coupling. In addition, the experimental
observation of this effect could be a way to assess the relevance of some
theoretical concepts of the braneworld hypothesis.Comment: 15 pages, 3 figures, final version published in European Physical
Journal
Identification of disease-relevant modulators of the SHH pathway in the developing brain
Pathogenic gene variants in humans that affect the sonic hedgehog (SHH) pathway lead to severe brain malformations with variable penetrance due to unknown modifier genes. To identify such modifiers, we established novel congenic mouse models. LRP2-deficient C57BL/6N mice suffer from heart outflow tract defects and holoprosencephaly caused by impaired SHH activity. These defects are fully rescued on a FVB/N background, indicating a strong influence of modifier genes. Applying comparative transcriptomics, we identified Pttg1 and Ulk4 as candidate modifiers upregulated in the rescue strain. Functional analyses showed that ULK4 and PTTG1, both microtubule-associated proteins, are positive regulators of SHH signaling, rendering the pathway more resilient to disturbances. In addition, we characterized ULK4 and PTTG1 as previously unidentified components of primary cilia in the neuroepithelium. The identification of genes that powerfully modulate the penetrance of genetic disturbances affecting the brain and heart is likely relevant to understanding the variability in human congenital disorders
MAGE-A as a novel approach in the diagnostic accuracy of oral squamous cell cancer: a case report
Nanomechanics of individual aerographite tetrapods
R.A., O.L. and K.S. would like to thank the German Research Foundation (DFG) for the financial support under schemes AD 183/17-1 and SFB 986-TP-B1, respectively, and the Graphene FET Flagship. R.M. and D.E. would like to thank for financial support from Latvian Council of Science, no. 549/2012. N.M.P. is supported by the European Research Council (ERC PoC 2015 SILKENE no. 693670) and by the European Commission H2020 under the Graphene Flagship (WP14 ‘Polymer Composites’, no. 696656) and under the FET Proactive (‘Neurofibres’ no. 732344). S.S. acknowledges support from SILKENE
- …