161 research outputs found
Phylogeny of the Genus Dichotrachelus (Coleoptera: Curculionidae: Cyclominae)
A phylogenetic analysis of the genus Dichotrachelus (Curculionidae: Cyclominae) was carried out, based on a morphological matrix and, for some species, on mitochondrial cytochrome oxidase I sequences. Bayesian Inference, Maximum Likelihood and Maximum Parsimony were implemented and the results were compared. The genus is found to be isolated in the subfamily, not related to the only other Palaearctic tribe (Hipporhinini) and possibly nearer to the south-American genera of Cyclominae of the tribe Listroderini. Among these, Macrostyphlus is also equally associated to mosses as the host plant. In Dichotrachelus, two main clades were recognized, one distributed in the western part of the Mediterranean region (Iberian Peninsula, northern Africa and southern France) and the second distributed in the Alps and Apennines. Within each clade, some differentiated monophyletic subgroups could be identified. An evaluation of the most important characters that led to the phylogenetic reconstruction indicated the male genital sclerite as the most useful structure to characterize the different clades
An anomalous alloy: Y_x Si_{1-x}
We study via density functional-based molecular dynamics the structural and
dynamical properties of the rare earth silicon amorphous alloy Y_xSi_{1-x} for
x=0.093 and x=0.156. The Si network forms cavities in which a Y^{3+} cation is
entrapped. Its electrons are transferred to the Si network and are located in
the dangling bonds of the Si atoms that line the Y cavities. This leads to the
presence of low coordinated Si atoms that can be described as monovalent or
divalent anions. For x=0.156, the cavities touch each other and share Si atoms
that have two dangling bonds. The vibrational spectrum is similar to that of
amorphous Si. However, doping induces a shoulder at 70 cm^{-1} and a pronounced
peak at 180 cm^{-1} due to low coordinated Si.Comment: 4 pages, 4 figure
Duchenne muscular dystrophy caused by a frame-shift mutation in the acceptor splice site of intron 26
Background: The dystrophin gene is the one of the largest described in human beings and mutations associated
to this gene are responsible for Duchenne or Becker muscular dystrophies.
Case Presentation: Here we describe a nucleotide substitution in the acceptor splice site of intron 26 (c.3604-1G >
C) carried by a 6-year-old boy who presented with a history of progressive proximal muscle weakness and elevated
serum creatine kinase levels. RNA analysis showed that the first two nucleotides of the mutated intron 26 (AC) were
not recognized by the splicing machinery and a new splicing site was created within exon 27, generating a
premature stop codon and avoiding protein translation.
Conclusions: The evaluation of the pathogenic effect of the mutation by mRNA analysis will be useful in the optics
of an antisense oligonucleotides (AON)-based therapy
Vaginal toxicity management in patients with locally advanced cervical cancer following exclusive chemoradiation—a nationwide survey on knowledge and attitudes by the Italian Association of Radiotherapy and Clinical Oncology (AIRO) Gynecology Study Group
Background and Objective: Exclusive radiotherapy, including external beam radiotherapy (EBRT) and interventional radiotherapy/brachytherapy (IRT/BT), with concurrent cisplatin-based chemotherapy, represents the standard of care in patients with locally advanced cervical cancer (LACC). The emerging topic of vaginal toxicity has become a key endpoint in LACC management, although different approaches and non-standardized procedures were available. Our aim was to analyze a nationwide study of the attitudes of Italian gynecological radiation oncology teams in the management of LACC patients' vaginal toxicities. Methods: A nationwide survey of radiation oncologists specializing in the treatment of gynecological malignancies was performed, using the free SurveyMonkey platform, consisting of 26 items. The questionnaire was proposed by the Italian Association of Radiation Oncologists (AIRO) gynecological working group to all 183 Italian radiation oncology institutions, as per AIRO's website. Results: Fifty-eight questionnaires (31%) were completed and returned. The assessment of acute and late vaginal toxicities was systematic in 32 (55.2%) and 26 (44.8%) centers, respectively. In the case of EBRT, 70.7% of centers, according to the contouring and treatment plan data, did not contour the vagina as an organ at risk (OAR). Vaginal dose constraints were heterogeneous for both EBRT and IRT/BT. Local treatment to prevent vaginal toxicity was prescribed by 60.3% of radiation oncologists, mostly vaginal hyaluronic acid cream, and one center recommended vaginal estrogen preparations. During follow-up visits, vaginal toxicity was considered an issue to be investigated always (n = 31) or in sexually active women only (n = 11). Conclusions: This survey showed that wide variation exists with regard to recording and treating vaginal toxicity after exclusive chemoradiation for cervical cancer, underscoring the need to develop more comprehensive guidelines for contouring e-dose reporting of the vagina, so as to implement clinical approaches for vaginal toxicity
Structural and superconducting transition in selenium under high pressures
First-principles calculations are performed for electronic structures of two
high pressure phases of solid selenium, -Po and bcc.
Our calculation reproduces well the pressure-induced phase transition from
-Po to bcc observed in selenium.
The calculated transition pressure is 30 GPa lower than the observed one, but
the calculated pressure dependence of the lattice parameters agrees fairly well
with the observations in a wide range of pressure.
We estimate the superconducting transition temperature of both
the -Po and the bcc phases by calculating the phonon dispersion and the
electron-phonon interaction on the basis of density-functional perturbation
theory.
The calculated shows a characteristic pressure dependence, i.e.
it is rather pressure independent in the -Po phase, shows a
discontinuous jump at the transition from -Po to bcc, and then decreases
rapidly with increasing pressure in the bcc phase.Comment: 8 pages, 11 figure
The optical response of Ba_{1-x}K_xBiO_3: Evidence for an unusual coupling mechanism of superconductivity?
We have analysed optical reflectivity data for Ba_{1-x}K_xBiO_3 in the
far-infrared region using Migdal-Eliashberg theory and found it inconsistent
with standard electron-phonon coupling: Whereas the superconducting state data
could be explained using moderate coupling, \lambda=0.7, the normal state
properties indicate \lambda \le 0.2. We have found that such behaviour could be
understood using a simple model consisting of weak standard electron-phonon
coupling plus weak coupling to an unspecified high energy excitation near 0.4
eV. This model is found to be in general agreement with the reflectivity data,
except for the predicted superconducting gap size. The additional high energy
excitation suggests that the dominant coupling mechanism in Ba_{1-x}K_xBiO_3 is
not standard electron-phonon.Comment: 5 pages REVTex, 5 figures, 32 refs, accepted for publication in Phys.
Rev.
Superconductivity near the vibrational mode instability in MgCNi3
To understand the role of electron-phonon interaction in superconducting
MgCNi we have performed density functional based linear response
calculations of its lattice dynamical properties. A large coupling constant = 1.51 is predicted and contributing phonons are identified as
displacements of Ni atoms towards octahedral interstitials of the perovskite
lattice. Instabilities found for some vibrational modes emphasize the role of
anharmonic effects in resolving experimental controversies.Comment: 4 pages, 4 eps figures, replaces the older versio
- …