162 research outputs found
Metastasis to parotid gland from non Head and Neck tumors
Most primary tumors spreading metastasis to the parotid gland are usually located in the head and neck region, nonetheless, rarely, parotid gland can also be the target of metastatic localization site of distant primary tumors. The purpose of this study was to describe a clinical series of metastasis to the parotid gland from distant primary tumors (non Head & Neck)
Ototoxicity prevention during the SARS-CoV-2 (COVID-19) emergency
Aim of this paper is to remind the risk of ototoxicity when using chloroquine and hydroxychloroquine, in particular as prophylactic agents against SARS-CoV-2, during the pandemic. Healthy subjects taking chloroquine and hydroxychloroquine as prophylactic agents against SARS-CoV-2, during the pandemic, should be screened periodically, at least by Otoacoustic Emissions (OAEs) in order to detect early manifestations of possible cochlear ototoxic damages
Indium segregation during III-V quantum wire and quantum dot formation on patterned substrates
We report a model for metalorganic vapor-phase epitaxy on non-planar
substrates, specifically V-grooves and pyramidal recesses, which we apply to
the growth of InGaAs nanostructures. This model, based on a set of coupled
reaction-diffusion equations, one for each facet in the system, accounts for
the facet-dependence of all kinetic processes (e.g., precursor decomposition,
adatom diffusion, and adatom lifetimes) and has been previously applied to
account for the temperature, concentration, and temporal-dependence of AlGaAs
nanostructures on GaAs (111)B surfaces with V-grooves and pyramidal recesses.
In the present study, the growth of InGaAs quantum wires at
the bottom of V-grooves is used to determine a set of optimized kinetic
parameters. Based on these parameters, we have modeled the growth of
InGaAs nanostructures formed in pyramidal site-controlled
quantum-dot systems, successfully producing a qualitative explanation for the
temperature-dependence of their optical properties, which have been reported in
previous studies. Finally, we present scanning electron and cross-sectional
atomic force microscopy images which show previously unreported facetting at
the bottom of the pyramidal recesses that allow quantum dot formation.Comment: 9 pages, 8 figure
Vertigo and Dizziness in Children: An Update
Background: Vertigo and dizziness are relatively infrequent in paediatric patients, but specific data on the prevalence of these disorders are limited and influenced by various factors, including the age of the examined population. These conditions often have a significant impact on patients' and parents' quality of life. The aim of this paper is to investigate the prevalence of different aetiologies of vertigo in the paediatric population through a systematic review.
Methods: According to PRISMA guidelines, a systematic review of the literature was performed. Medline and Embase were searched from January 2011 through to 10 September 2021. The search yielded 1094 manuscripts, which were reduced to 7 upon the application of inclusion criteria.
Results: A total of 2470 paediatric patients were evaluated by the selected papers. Vestibular Migraine was the most frequently diagnosed condition, occurring alone or in association with other diseases. Overall, audio-vestibular disorders represented the second cause of vertigo, and the prevalence appears to increase according to age growth. Over the years, even though we assisted in the amelioration of diagnostic rates, partially related to an improvement in diagnostic tools, the aetiology of vertigo remains still unclear in a variable percentage of patients.
Conclusion: Vertigo in children, despite being an uncommon symptom, requires a multidisciplinary approach, often involving Paediatricians, Neurologists and Otorhinolaryngologists. A comprehensive evaluation of children suffering from vertigo is crucial for establishing a successful therapy and reducing parental worries
Statistical study of stacked/coupled site-controlled pyramidal quantum dots and their excitonic properties
We report on stacked multiple quantum dots (QDs) formed inside inverted pyramidal recesses, which allow for the precise positioning of the QDs themselves. Specifically, we fabricated double QDs with varying inter-dot distances and ensembles with more than two nominally highly symmetric QDs. For each, the effect of the interaction between QDs is studied by characterizing a large number of QDs through photoluminescence spectroscopy. A clear red-shift of the emission energy is observed together with a change in the orientation of its polarization, suggesting an increasing interaction between the QDs. Finally, we show how stacked QDs can help influencing the charging of the excitonic complexes
Genetic Polymorphisms in Sudden Sensorineural Hearing Loss: An Update
Objective: To investigate the association between genetic polymorphisms and sudden sensorineural hearing loss (SSNHL). Most of the SSNHL cases still remain idiopathic, and several etiopathogenetic hypotheses, including a genetic predisposition, have been proposed. Methods: A literature review was conducted using different databases: Medline/PubMed, EMBASE, and CINAHL, according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. All databases have been searched from May 2016 to April 2020. Results: Genetic susceptibility could represent a key element in the pathogenesis of SSNHL. A number of genetic polymorphisms related to (1) inner ear microvascular disease and endothelial dysfunction and (2) to inner ear oxidative stress and inflammation have been addressed in the current literature. Conclusions: The potential identification of a genetic profile related to SSNHL could provide a more accurate prognostic evidence of idiopathic SSNHL (ISSNHL), offering to the patients not only early-prevention strategies but eventually information on various inheritance modalities. © The Author(s) 2020
Tuning InP self-assembled quantum structures to telecom wavelength: A versatile original InP(As) nanostructure "workshop"
The influence of hydride exposure on previously unreported self-assembled InP(As) nanostructures is investigated, showing an unexpected morphological variability with growth parameters, and producing a large family of InP(As) nanostructures by metalorganic vapour phase epitaxy, from dome and ring-like structures to double dot in a ring ensembles. Moreover, preliminary microphotoluminescence data are indicating the capped rings system as an interesting candidate for single quantum emitters at telecom wavelengths, potentially becoming a possible alternative to InAs QDs for quantum technology and telecom applications
Droplet etching of deep nanoholes for filling with self-aligned complex quantum structures
Strain-free epitaxial quantum dots (QDs) are fabricated by a combination of Al local droplet etching (LDE) of nanoholes in AlGaAs surfaces and subsequent hole filling with GaAs. The whole process is performed in a conventional molecular beam epitaxy (MBE) chamber. Autocorrelation measurements establish single-photon emission from LDE QDs with a very small correlation function g (2)(0)≃ 0.01 of the exciton emission. Here, we focus on the influence of the initial hole depth on the QD optical properties with the goal to create deep holes suited for filling with more complex nanostructures like quantum dot molecules (QDM). The depth of droplet etched nanoholes is controlled by the droplet material coverage and the process temperature, where a higher coverage or temperature yields deeper holes. The requirements of high quantum dot uniformity and narrow luminescence linewidth, which are often found in applications, set limits to the process temperature. At high temperatures, the hole depths become inhomogeneous and the linewidth rapidly increases beyond 640 °C. With the present process technique, we identify an upper limit of 40-nm hole depth if the linewidth has to remain below 100 μeV. Furthermore, we study the exciton fine-structure splitting which is increased from 4.6 μeV in 15-nm-deep to 7.9 μeV in 35-nm-deep holes. As an example for the functionalization of deep nanoholes, self-aligned vertically stacked GaAs QD pairs are fabricated by filling of holes with 35 nm depth. Exciton peaks from stacked dots show linewidths below 100 μeV which is close to that from single QDs
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