389 research outputs found
Common Gene Variants in Schizophrenia Susceptibility with Focus on Neurodevelopment
Schizophrenia is a severe multifactorial mental disorder with an important and complex genetic component, and the understanding of the underlying biological mechanisms is limited. Several lines of evidence support that abnormal neurodevelopment is involved, such as cognitive deficits in children who later develop schizophrenia, abnormalities in brain structure in the early phase of disease, and aberrant neuronal distributions. Also, glutamatergic dysfunctions are suggested in the schizophrenia etiology, and glutamate signalling is important during neurodevelopment. Perineuronal nets are extracellular matrix structures involved in brain maturation, which includes the characteristic neural epitope Human Natural Killer-1 (HNK-1).
To investigate if common gene variants important for neurodevelopment are involved in schizophrenia etiology, we used candidate gene-based association studies of tagSNPs spanning thirty genes, genotyped in a large Scandinavian case-control sample (SCOPE). Nineteen, out of the 289 tagSNPs in 18 neuronal migration genes, were nominally significant, and the strongest finding was a tagSNP located in MAM domain containing glycosylphosphatidylinositol anchor 1 (MDGA1), but no findings were significant after correction.
Phosphodiesterase 4B (PDE4B) is a Disrupted-in-Schizophrenia-1 (DISC1) interactor, with previously reported genetic associations only in women. Six and 16, out of 40 and 72 PDE4B tagSNPs, were nominally associated with schizophrenia and bipolar disorder, respectively, in the combined samples or in gender-specific subgroups. No findings were significant after correction. However, two of the tagSNPs nominally associated in schizophrenia females had proxies which were nominally associated in the total bipolar disorder sample, and the four SNPs were located in the same block, surrounding the splice site for the PDE4B3 isoform.
Five out of 104 tagSNPs in ten genes involved in perineuronal net formation and HNK-1 biosynthesis, located in beta-1,3-glucuronyltransferase 2 (B3GAT2), were nominally associated with schizophrenia. The association signal for tagSNPs in one of the LD blocks was replicated by proxy SNPs in a much larger European sample (SGENE-plus).
Six out of 30 tagSNPs in glutamate receptor ionotrophic kainate 3 (GRIK3) were nominally associated, and the best tagSNP were significant after correction, with increased significance in the Swedish subsample, as well as when the risk allele was combined with another tagSNP risk allele.
When investigating clinical characteristics, including positive and negative symptom scores, age at onset, and cognitive measures of learning, memory and IQ, for association with a subset of the tagSNPs and genes included in the thesis studies, there were no significant associations after correction.
The current results indicate that gene variants involved in neurodevelopment are associated with schizophrenia, which further supports the neurodevelopmental hypothesis
Generalized Gauge Theories and Weinberg-Salam Model with Dirac-K\"ahler Fermions
We extend previously proposed generalized gauge theory formulation of
Chern-Simons type and topological Yang-Mills type actions into Yang-Mills type
actions. We formulate gauge fields and Dirac-K\"ahler matter fermions by all
degrees of differential forms. The simplest version of the model which includes
only zero and one form gauge fields accommodated with the graded Lie algebra of
supergroup leads Weinberg-Salam model. Thus the Weinberg-Salam model
formulated by noncommutative geometry is a particular example of the present
formulation.Comment: 33 pages, LaTe
The role of carbonaceous deposits in the activity and stability of Ni-based catalysts applied in the dry reforming of methane
Highly stable Ni catalysts with varying Ni contents up to 50 mol% originating from hydrotalcite-like precursors were applied in the dry reforming of methane at 800 and 900 °C. The integral specific rate of methane conversion determined after 10 h on stream was 3.8 mmol s-1 gcat-1 at 900 °C. Due to the outstanding high activity, a catalyst mass of just 10 mg had to be used to avoid operating the reaction in thermodynamic equilibrium. The resulting WHSV was as high as 1.44 × 106 ml gcat-1 h-1. The observed axial temperature distribution with a pronounced cold spot was analyzed by computational fluid dynamics simulations to verify the strong influence of this highly endothermic reaction. Transmission electron microscopy and temperature-programmed oxidation experiments were used to probe the formation of different carbon species, which was found to depend on the catalyst composition and the reaction temperature. Among the formed carbon species, multi-walled carbon nanofibers were detrimental to the long-term stability at 800 °C, whereas their formation was suppressed at 900 °C. The formation of graphitic carbon at 900 °C originating from methane pyrolysis played a minor role. The methane conversion after 100 h of dry reforming at 900 °C compared to the initial one amounted to 98% for the 25 mol% Ni catalyst. The oxidative regeneration of the catalyst was achieved in the isothermal mode using only carbon dioxide in the feed
An interpolation problem arising in a coupling of the finite element method with holomorphic basis functions
The purpose of this paper is to prove an interpolation theorem which arises in a method of coupling of a finite
element and an analytical solution for boundary value problems with singularities
Genetics of Tinnitus: Time to Biobank Phantom Sounds
Tinnitus is a common phantom sensation resulting most often from sensory deprivation, and for which little knowledge on the molecular mechanisms exists. While the existing evidence for a genetic influence on the condition has been until now sparse and underpowered, recent data suggest that specific forms of tinnitus have a strong genetic component revealing that not all tinnitus percepts are alike, at least in how they are genetically driven. These new findings pave the way for a better understanding on how phantom sensations are molecularly driven and call for international biobanking efforts
On local boundary CFT and non-local CFT on the boundary
The holographic relation between local boundary conformal quantum field
theories (BCFT) and their non-local boundary restrictions is reviewed, and
non-vacuum BCFT's, whose existence was conjectured previously, are constructed.Comment: 16 pages. Contribution to "Rigorous Quantum Field Theory", Symposium
in honour of J. Bros, Paris, July 2004. Based on joint work math-ph/0405067
with R. Long
Riemann-Hilbert problems for poly-Hardy space on the unit ball
In this paper, we focus on a Riemann–Hilbert boundary value problem (BVP)
with a constant coefficients for the poly-Hardy space on the real unit ball in
higher dimensions. We first discuss the boundary behaviour of functions in the
poly-Hardy class. Then we construct the Schwarz kernel and the higher order
Schwarz operator to study Riemann–Hilbert BVPs over the unit ball for the poly-
Hardy class. Finally, we obtain explicit integral expressions for their solutions.
As a special case, monogenic signals as elements in the Hardy space over the
unit sphere will be reconstructed in the case of boundary data given in terms
of functions having values in a Clifford subalgebra. Such monogenic signals
represent the generalization of analytic signals as elements of the Hardy space over the unit circle of the complex plane
A condensed matter interpretation of SM fermions and gauge fields
We present the bundle Aff(3) x C x /(R^3), with a geometric Dirac equation on
it, as a three-dimensional geometric interpretation of the SM fermions. Each C
x /(R^3) describes an electroweak doublet. The Dirac equation has a
doubler-free staggered spatial discretization on the lattice space Aff(3) x C
(Z^3). This space allows a simple physical interpretation as a phase space of a
lattice of cells in R^3. We find the SM SU(3)_c x SU(2)_L x U(1)_Y action on
Aff(3) x C x /(R^3) to be a maximal anomaly-free special gauge action
preserving E(3) symmetry and symplectic structure, which can be constructed
using two simple types of gauge-like lattice fields: Wilson gauge fields and
correction terms for lattice deformations. The lattice fermion fields we
propose to quantize as low energy states of a canonical quantum theory with
Z_2-degenerated vacuum state. We construct anticommuting fermion operators for
the resulting Z_2-valued (spin) field theory. A metric theory of gravity
compatible with this model is presented too.Comment: Minimal modifications in comparison with the published versio
Angular momentum and mass evolution of contact binaries
Various scenarios of contact binary evolution have been proposed in the past,
giving hints of (sometimes contradictory) evolutionary sequence connecting
A-type and W-type systems. As the components of close detached binaries
approach each other and contact binaries are formed, following evolutionary
paths transform them into systems of two categories: A-type and W-type. The
systems evolve in a similar way but under slightly different circumstances. The
mass/energy transfer rate is different, leading to quite different evolutionary
results. An alternative scenario of evolution in contact is presented and
discussed, based on the observational data of over a hundred low-temperature
contact binaries. It results from the observed correlations among contact
binary physical and orbital parameters. Theoretical tracks are computed
assuming angular momentum loss from a system via stellar wind, accompanied by
mass transfer from an advanced evolutionary secondary to the main sequence
primary. Good agreement is seen between the tracks and the observed graphs.
Independently of details of the evolution in contact and a relation between
A-type and W-type systems, the ultimate fate of contact binaries involves the
coalescence of both components into a single fast rotating star.Comment: 11 pages, 5 figures, a short paragraph added on p. 6, MNRAS, in pres
Positivity and conservation of superenergy tensors
Two essential properties of energy-momentum tensors T_{\mu\nu} are their
positivity and conservation. This is mathematically formalized by,
respectively, an energy condition, as the dominant energy condition, and the
vanishing of their divergence \nabla^\mu T_{\mu\nu}=0. The classical Bel and
Bel-Robinson superenergy tensors, generated from the Riemann and Weyl tensors,
respectively, are rank-4 tensors. But they share these two properties with
energy momentum tensors: the Dominant Property (DP) and the divergence-free
property in the absence of sources (vacuum). Senovilla defined a universal
algebraic construction which generates a basic superenergy tensor T{A} from any
arbitrary tensor A. In this construction the seed tensor A is structured as an
r-fold multivector, which can always be done. The most important feature of the
basic superenergy tensors is that they satisfy automatically the DP,
independently of the generating tensor A. In a previous paper we presented a
more compact definition of T{A} using the r-fold Clifford algebra. This form
for the superenergy tensors allowed to obtain an easy proof of the DP valid for
any dimension. In this paper we include this proof. We explain which new
elements appear when we consider the tensor T{A} generated by a
non-degree-defined r-fold multivector A and how orthogonal Lorentz
transformations and bilinear observables of spinor fields are included as
particular cases of superenergy tensors. We find some sufficient conditions for
the seed tensor A, which guarantee that the generated tensor T{A} is
divergence-free. These sufficient conditions are satisfied by some physical
fields, which are presented as examples.Comment: 19 pages, no figures. Language and minor changes. Published versio
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