10,799 research outputs found
Congenital muscular dystrophy: from muscle to brain.
Congenital muscular dystrophies (CMDs) are a wide group of muscular disorders that manifest with very early onset of muscular weakness, sometime associated to severe brain involvement.The histologic pattern of muscle anomalies is typical of dystrophic lesions but quite variable depending on the different stages and on the severity of the disorder.Recent classification of CMDs have been reported most of which based on the combination of clinical, biochemical, molecular and genetic findings, but genotype/phenotype correlation are in constant progression due to more diffuse utilization of the molecular analysis.In this article, the Authors report on CMDs belonging to the group of dystroglycanopathies and in particular on the most severe forms represented by the Fukuyama CMD, Muscle-Eye-Brain disease and Walker Walburg syndrome.Clinical diagnosis of infantile hypotonia is particularly difficult considering the different etiologic factors causing the lesions, the difficulty in localizing the involved CNS area (central vs. peripheral) and the limited role of the diagnostic procedures at this early age.The diagnostic evaluation is not easy mainly in differentiating the various types of CMDs, and represents a challenge for the neonatologists and pediatricians. Suggestions are reported on the way to reach a correct diagnosis with the appropriate use of the diagnostic means
The stress-corrosion behavior of Al-Li-Cu alloys: A comparison of test methods
Two powder metallurgy processed (Al-Li-Cu) alloys with and without Mg addition were studied in aqueous 3.5% NaCl solution during the alternate immersion testing of tuning fork specimens, slow crack growth tests using fracture mechanics specimens, and the slow strain rate testing of straining electrode specimens. Scanning electron microscopy and optical metallography were used to demonstrate the character of the interaction between the Al-Li-Cu alloys and the selected environment. Both alloys are susceptible to SC in an aqueous 3.5% NaCl solution under the right electrochemical and microstructural conditions. Each test method yields important information on the character of the SC behavior. Under all conditions investigated, second phase particles strung out in rows along the extrusion direction in the alloys were rapidly attacked, and played principal role in the SC process. With time, larger pits developed from these rows of smaller pits and under certain electrochemical conditions surface cracks initiated from the larger pits and contributed directly to the fracture process. Evidence to support slow crack growth was observed in both the slow strain rate tests and the sustained immersion tests of precracked fracture mechanics specimens. The possible role of H2 in the stress corrosion cracking process is suggested
Observation of the Inverse Cotton-Mouton Effect
We report the observation of the Inverse Cotton-Mouton Effect (ICME) i.e. a
magnetization induced in a medium by non resonant linearly polarized light
propagating in the presence of a transverse magnetic field. We present a
detailed study of the ICME in a TGG crystal showing the dependence of the
measured effect on the light intensity, the optical polarization, and on the
external magnetic field. We derive a relation between the Cotton-Mouton and
Inverse Cotton-Mouton effects that is roughly in agreement with existing
experimental data. Our results open the way to applications of the ICME in
optical devices
A clinical review on megalencephaly: A large brain as a possible sign of cerebral impairment.
Megalencephaly and macrocephaly present with a head circumference measurement 2 standard deviations above the age-related mean. However, even if pathologic events resulting in both megalencephaly and macrocephaly may coexist, a distinction between these two entities is appropriate, as they represent clinical expression of different disorders with a different approach in clinical work-up, overall prognosis, and treatment. Megalencephaly defines an increased growth of cerebral structures related to dysfunctional anomalies during the various steps of brain development in the neuronal proliferation and/or migration phases or as a consequence of postnatal abnormal events. The disorders associated with megalencephaly are classically defined into 3 groups: idiopathic or benign, metabolic, and anatomic. In this article, we seek to underline the clinical aspect of megalencephaly, emphasizing the main disorders that manifest with this anomaly in an attempt to properly categorize these disorders within the megalencephaly group
A new look at Sco OB1 association with Gaia DR2
We present and discuss photometric optical data in the area of the OB
association Sco OB1 covering about 1 squared degree. UBVI photometry is
employed in tandem with Gaia DR2 data to investigate the 3 dimensional
structure and the star formation history of the region. By combining parallaxes
and proper motions we identify 7 physical groups located between the young open
cluster NGC 6231 and the bright nebula IC4628. The most prominent group
coincides with the sparse open cluster Trumpler 24. We confirm the presence of
the intermediate age star cluster VdB-Hagen 202, which is unexpected in this
environment, and provide for the first time estimates of its fundamental
parameters. After assessing individual groups membership, we derive mean proper
motion components, distances, and ages. The seven groups belong to two
different families. To the younger family (family I) belong several pre-Main
Sequence stars as well. These are evenly spread across the field, and also in
front of VdB-Hagen 202. VdB-Hagen 202 and two smaller, slightly detached,
groups of similar properties form family II, which do not belong to the
association, but are caught in the act of passing through it. As for the
younger population, this forms an arc-like structure from the bright nebula IC
4628 down to NGC 6231, as previously found. Moreover, the pre-Main Sequence
stars density seems to increase from NGC 6231 northward to Trumpler 24
Single Production in Collisions at the NLC
Single production in collisions at the NLC can be used to
probe the Majorana nature of the heavy neutrinos present in the Left-Right
Symmetric Model below the kinematic threshold for their direct production. For
colliders in the TeV range, typical cross sections of order
are obtained, depending on the specific choice of model parameters.
Backgrounds arising from Standard Model processes are shown to be small. This
analysis greatly extends the kinematic range of previous studies wherein the
production of an on-shell, like-sign pair of 's at the NLC was considered.Comment: 13pp, 3 figures (available on request), LaTex, SLAC-PUB-647
Quantum Gravity Effects in Black Holes at the LHC
We study possible back-reaction and quantum gravity effects in the
evaporation of black holes which could be produced at the LHC through a
modification of the Hawking emission. The corrections are phenomenologically
taken into account by employing a modified relation between the black hole mass
and temperature. The usual assumption that black holes explode around TeV
is also released, and the evaporation process is extended to (possibly much)
smaller final masses. We show that these effects could be observable for black
holes produced with a relatively large mass and should therefore be taken into
account when simulating micro-black hole events for the experiments planned at
the LHC.Comment: 14 pages, 8 figures, extended version of hep-ph/0601243 with new
analysis of final products, final version accepted for publication in J.
Phys.
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