254 research outputs found
Production of Long-Lived Sleptons at LHC
We analyse the MSSM parameter space and discuss the narrow band near the
so-called co-annihilation region where sleptons may be long-lived particles.
This region is consistent with the WMAP restrictions on the Dark matter and
depends on the value of . In this region staus are long-lived and
may go through the detector. Due to a relatively small mass (150 850
GeV) their production cross-section at LHC may reach a few % pb.Comment: LaTex, 8 pages, 6 eps figure
A bridge for two views: Checkland’s soft systems methodology and Maturana’s ontology of the observer
© 2019, © Operational Research Society 2019. Checkland and Maturana’s work aim to understand and to improve problematic situations in organisations and in our everyday life. Maturana’s phenomenological onto-epistemology (we are immersed in the praxis of living in an ontological multi-universe) seems to resonate with Soft Systems Methodology (SSM) interpretivist epistemology. We argue that this concurrence makes it possible to reflect and explore some of Maturana’s ideas (structural determinism/structural coupling/organisational closure) when they are grafted into the phases of the Checkland’s SSM seven-step process. This article aims to complement SSM by proposing a framework in which some key concepts from Maturana’s Ontology of the Observer (OoO) might enhance and expand the understanding of the SSM application process. An enriched and enhanced SSM process could have significant consequences in the Management Science/Operational Research (MS/OR) and Systems community practice. The framework proposed can have major social repercussions since it will incorporate the well-known influential OoO ideas into MS/OR practice
Long-lived Charginos in the Focus-point Region of the MSSM Parameter Space
We analyse the possibility to get light long-lived charginos within the
framework of the MSSM with gravity mediated SUSY breaking. We find out that
this possibility can be realized in the so-called focus-point region of
parameter space. The mass degeneracy of higgsino-like chargino and two
higgsino-like neutralinos is the necessary condition for a long lifetime. It
requires the fine-tuning of parameters, but being a single additional
constraint in the whole parameter space it can be fulfilled in the Constrained
MSSM along the border line where radiative electroweak symmetry breaking fails.
In a narrow band close to the border line the charginos are long-lived
particles. The cross-sections of their production and co-production at the LHC
via electroweak interaction reach a few tenth of pb.Comment: LaTeX, 11 pages, 11 eps figure
Hypospadias as a novel feature in spinal bulbar muscle atrophy
Spinal and bulbar muscle atrophy (SBMA) is an X-linked neuromuscular disorder
caused by CAG repeat expansions in the androgen receptor (AR) gene. The SBMA
phenotype consists of slowly progressive neuromuscular symptoms and
undermasculinization features as the result of malfunction of the AR. The latter
mainly includes gynecomastia and infertility. Hypospadias is also a feature of
undermasculinization with an underdeveloped urethra and penis; it has not been
described as part of the SBMA phenotype but has been suggested to be associated
with a prolonged CAG repeat in the AR gene. This study includes the first
epidemiologic description of the co-occurrence of hypospadias and SBMA in
subjects and their male relatives in Swedish population-based health registers,
as well as an additional clinical case. One boy with severe hypospadias was
screened for mutations in the AR gene and was found to have 42 CAG repeats in it,
which is in the full range of mutations causing SBMA later in life. We also
detected a maximum of four cases displaying the combination of SBMA and
hypospadias in our national register databases. This is the third case report
with hypospadias in association with CAG repeat expansions in the AR gene in the
full range known to cause SBMA later in life. Our findings suggest that
hypospadias may be an under diagnosed feature of the SBMA phenotype and we
propose that neurologists working with SBMA further investigate and report the
true prevalence of hypospadias among patients with SBMA.Swedish Research Council, K2012-64X-14506-10-5Stockholm City CouncilFoundation Frimurare Barnhuset in StockholmSwedish Research Council through the Swedish Initiative for Research on Microdata in the Social And Medical Sciences (SIMSAM), 340-2013-5867Accepte
Slurry preparation methods affect dental porcelain reliability
One-step and incremental mixing procedures are currently used to produce dental ceramic pastes. In the ceramic industry, high quality is obtained using
one-step mixing, but in dentistry, the best method has not been yet determined.
The purpose of this study is to evaluate the effects of 2 mixing techniques on the biaxial flexural strength and microstructure of dental porcelain.
Feldspathic porcelain discs (2 × 15 mm in diameter) were produced and divided according to the ceramic paste preparation method, powder-liquid incremental
mixing group (n=50) or one-step mixing, as a control group (n=50). Specimens were tested for biaxial flexural strength and characterized using porosimetry,
relative humidity, SEM/EDS, XRD, and FT-IR analyses. Statistical analysis was conducted using Weibull statistics. The Weibull modulus, characteristic strength
and relative humidity were compared between groups, using Student's t-test and Mann-Whitney U test (a=.05).
The powder-liquid incremental mixing group showed significantly higher values (SD) of Weibull modulus (6.74 (0.70), P<.001) and characteristic strength
(79.87 (2.01) MPa, P<.001) when compared to the one-step mixing group (4.94 (0.94) and 75.95 (2.61) MPa). Significantly lower mean (SD) relative humidity
values (P=.009) were found for powder-liquid incremental mixing group (20% (0.5%)) compared to one-step mixing group (22% (1%)). XRD spectra showed
that the one-step mixing group produced higher amounts of the amorphous phase.
Specimens produced by the incremental mixing technique showed higher biaxial flexural strength than one-step mixing
Maternal embryonic leucine zipper kinase (MELK) regulates multipotent neural progenitor proliferation.
Maternal embryonic leucine zipper kinase (MELK) was previously identified in a screen for genes enriched in neural progenitors. Here, we demonstrate expression of MELK by progenitors in developing and adult brain and that MELK serves as a marker for self-renewing multipotent neural progenitors (MNPs) in cultures derived from the developing forebrain and in transgenic mice. Overexpression of MELK enhances (whereas knockdown diminishes) the ability to generate neurospheres from MNPs, indicating a function in self-renewal. MELK down-regulation disrupts the production of neurogenic MNP from glial fibrillary acidic protein (GFAP)-positive progenitors in vitro. MELK expression in MNP is cell cycle regulated and inhibition of MELK expression down-regulates the expression of B-myb, which is shown to also mediate MNP proliferation. These findings indicate that MELK is necessary for proliferation of embryonic and postnatal MNP and suggest that it regulates the transition from GFAP-expressing progenitors to rapid amplifying progenitors in the postnatal brain
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