263 research outputs found
Sporadic high-grade malignant peripheral nerve sheath tumor of the hypoglossal nerve
Malignant tumors of peripheral nerve sheaths (MPNSTs) are rare malignant soft tissue tumors arising either from a peripheral nerve or from a pre-existing benign nerve sheath tumor. They occur most often in the context of Neurofibromatosis type-1 (NF-1) and are characterized by poor prognosis and aggressive behavior with a high rate of recurrence and distant metastases. We describe a 50-year-old woman who presented with right neck swelling, progressive dysphagia and tongue paresis. Imaging analysis revealed a mass involving the right parapharyngeal space. The tumor was excissed through a transcervical approach. At surgery, the tumor was strictly adherent to the hypoglossal nerve. Pathologic evaluation of the mass revealed a high-grade MPNST. Based on the pathological diagnosis, a clinical work-up for NF-1 was performed but it resulted negative. Occurrence of sporadic high-grade MPNST in the parapharyngeal space is rare and development from the hypoglossal nerve exceptional. As far as we know, only in two cases, both with clinical features consistent with NF1, the tumor was reported to be arised from the hypoglossal nerve
Distinctive physiological muscle synergy patterns define the Box and Block Task execution as revealed by electromyographic features
Stroke survivors experience muscular pattern alterations of the upper limb that decrease their ability to perform daily-living activities. The Box and Block test (BBT) is widely used to assess the unilateral manual dexterity. Although BBT provides insights into functional performance, it returns limited information about the mechanisms contributing to the impaired movement. This study aims at exploring the BBT by means of muscle synergies analysis during the execution of BBT in a sample of 12 healthy participants with their dominant and non-dominant upper limb. Results revealed that: (i) the BBT can be described by 1 or 2 synergies; the number of synergies (ii) does not differ between dominant and non-dominant sides and (iii) varies considering each phase of the task; (iv) the transfer phase requires more synergies. Clinical Relevance— This preliminary study characterizes muscular synergies during the BBT task in order to establish normative patterns that could assist in understanding the neuromuscular demands and support future evaluations of stroke deficit
Early stage of CVD graphene synthesis on Ge(001) substrate
In this work we shed light on the early stage of the chemical vapor
deposition of graphene on Ge(001) surfaces. By a combined use of microRaman and
x-ray photoelectron spectroscopies, and scanning tunneling microscopy and
spectroscopy, we were able to individuate a carbon precursor phase to graphene
nucleation which coexists with small graphene domains. This precursor phase is
made of C aggregates with different size, shape and local ordering which are
not fully sp2 hybridized. In some atomic size regions these aggregates show a
linear arrangement of atoms as well as the first signature of the hexagonal
structure of graphene. The carbon precursor phase evolves in graphene domains
through an ordering process, associated to a re-arrangement of the Ge surface
morphology. This surface structuring represents the embryo stage of the
hills-and-valleys faceting featured by the Ge(001) surface for longer
deposition times, when the graphene domains coalesce to form a single layer
graphene film
Abrupt changes in the graphene on Ge(001) system at the onset of surface melting
By combining scanning probe microscopy with Raman and x-ray photoelectron
spectroscopies, we investigate the evolution of CVD-grown graphene/Ge(001) as a
function of the deposition temperature in close proximity to the Ge melting
point, highlighting an abrupt change of the graphene's quality, morphology,
electronic properties and growth mode at 930 degrees. We attribute this
discontinuity to the incomplete surface melting of the Ge substrate and show
how incomplete melting explains a variety of diverse and long-debated peculiar
features of the graphene/Ge(001), including the characteristic nanostructuring
of the Ge substrate induced by graphene overgrowth. We find that the
quasi-liquid Ge layer formed close to 930 degrees is fundamental to obtain
high-quality graphene, while a temperature decrease of 10 degrees already
results in a wrinkled and defective graphene film.Comment: in pres
Tracking interfacial changes of graphene/Ge(110) during in-vacuum annealing
Graphene quality indicators obtained by Raman spectroscopy have been
correlated to the structural changes of the graphene/Germanium interface as a
function of in-vacuum thermal annealing. Specifically, it is found that
graphene becomes markedly defected at 650 {\deg}C. By combining scanning
tunneling microscopy, x-Ray Photoelectron Spectroscopy and Near Edge x-ray
Absorption Fine Structure Spectroscopy, we conclude that these defects are due
to the release of H_{2} gas trapped at the graphene/Germanium interface. The
H_{2} gas was produced following the transition from the as-grown
hydrogen-termination of the Ge(110) surface to the emergence of surface
reconstructions in the substrate. Interestingly, a complete self-healing
process is observed in graphene upon annealing to 800 {\deg}C. The subtle
interplay revealed between the microscopic changes occurring at the
graphene/Germanium interface and graphene's defect density is valuable for
advancing graphene growth, controlled 2D-3D heterogeneous materials interfacing
and integrated fabrication technology on semiconductors
Driving with temperature the synthesis of graphene films on Ge(110)
We systematically investigate the chemical vapor deposition growth of
graphene on Ge(110) as a function of the deposition temperature close to the Ge
melting point. By merging spectroscopic and morphological information, we find
that the quality of graphene films depends critically on the growth temperature
improving significantly by increasing this temperature in the 910-930 {\deg}C
range. We correlate the abrupt improvement of the graphene quality to the
formation of a quasi-liquid Ge surface occurring in the same temperature range,
which determines increased atom diffusivity and sublimation rate. Being
observed for diverse Ge orientations, this process is of general relevance for
graphene synthesis on Ge
The secretory senescence in otorhinolaryngology: Principles of treatment
Atrophy or hypofunction of the salivary gland because of aging, radiotherapy or disease causes hyposalivation and impairs the quality of life of patients by compromising mastication, swallowing and speech and by leading to a loss of taste. Moreover, hyposalivation exacerbates dental caries and induces periodontal disease, and oral candidiasis. Currently, no satisfactory therapies have been established to solve salivary hypofunction. Current treatment options for atrophy or hypofunction of the salivary glands in clinical practice are only symptomatic and include saliva substitutes and parasympathetic agonists, such as pilocarpine, to stimulate salivary flow. However, parasympathomimetics have systemic side effects, so different treatment options are necessary, and research has recently focused on this. The main strategies that have been proposed to restore salivary gland atrophy and hypofunction are gene therapy by gene activation/silencing during stem cell differentiation and by the use of viral vectors, such as adenoviruses; cell-based therapy with salivary gland cells, stem cells and non-salivary gland and/ or non-epithelial cells to regenerate damaged salivary gland cells; replacement with tissue bioengineering in which organoids from pluripotent stem cells are used in the development of organ replacement regenerative therapy. Remarkable progression in this research field has been made in the last decade, but a definitive therapy for salivary gland hypofunction has not been developed due to intrinsic challenges that come with each approach. However, with research efforts in the future, a range of precision medicine therapies may become available individualized to each patient
Two-domains bulklike Fermi surface of Ag films deposited onto Si(111)-(7x7)
Thick metallic silver films have been deposited onto Si(111)-(7x7) substrates
at room temperature. Their electronic properties have been studied by using
angle resolved photoelectron spectroscopy (ARPES). In addition to the
electronic band dispersion along the high-symmetry directions, the Fermi
surface topology of the grown films has been investigated. Using ARPES, the
spectral weight distribution at the Fermi level throughout large portions of
the reciprocal space has been determined at particular perpendicular
electron-momentum values. Systematically, the contours of the Fermi surface of
these films reflected a sixfold symmetry instead of the threefold symmetry of
Ag single crystal. This loss of symmetry has been attributed to the fact that
these films appear to be composed by two sets of domains rotated 60 from
each other. Extra, photoemission features at the Fermi level were also
detected, which have been attributed to the presence of surface states and
\textit{sp}-quantum states. The dimensionality of the Fermi surface of these
films has been analyzed studying the dependence of the Fermi surface contours
with the incident photon energy. The behavior of these contours measured at
particular points along the Ag L high-symmetry direction puts forward
the three-dimensional character of the electronic structure of the films
investigated.Comment: 10 pages, 12 figures, submitted to Physical Review
Superconductivity in Fullerides
Experimental studies of superconductivity properties of fullerides are
briefly reviewed. Theoretical calculations of the electron-phonon coupling, in
particular for the intramolecular phonons, are discussed extensively. The
calculations are compared with coupling constants deduced from a number of
different experimental techniques. It is discussed why the A_3 C_60 are not
Mott-Hubbard insulators, in spite of the large Coulomb interaction. Estimates
of the Coulomb pseudopotential , describing the effect of the Coulomb
repulsion on the superconductivity, as well as possible electronic mechanisms
for the superconductivity are reviewed. The calculation of various properties
within the Migdal-Eliashberg theory and attempts to go beyond this theory are
described.Comment: 33 pages, latex2e, revtex using rmp style, 15 figures, submitted to
Review of Modern Physics, more information at
http://radix2.mpi-stuttgart.mpg.de/fullerene/fullerene.htm
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