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Some cultured and natural pearls can be reliably distinguished by visual inspection and by the use of lens and microscope. However, assessing the origin of the pearls could be not straightforward since many different production techniques can now be found in the pearl market, for example in salt or freshwater environments, with or without a rigid nucleus. This wide range of products requires the use of new effective scientific techniques. Indeed, X-ray radiography has been used by gemologists since last century as the only safe and non-destructive way to visually inspect the interior of a pearl, and recently, also X-ray computed micro-tomography was used to better visualize the inner parts of the gems. In this study we analyzed samples of natural and cultured pearls by means of two non-destructive techniques: the X-ray Phase-Contrast Imaging (PCI) and the Neutron Imaging (NI). PCI and NI results will be combined for the first time, to better visualize the pearls internal morphology, thus giving relevant indications on the pearl formation process.

We present the dimensioning of a photon-photon collider based on Compton gamma sources for the observation of Breit-Wheeler pair production and QED γγ events. Two symmetric electron beams, generated by photocathodes and accelerated in linacs, produce two gamma ray beams through Compton back scattering with two J-class lasers. Tuning the system energy above the Breit-Wheeler cross section threshold, a flux of electron-positron pairs is generated out of light-light interaction. The process is analyzed by start-to-end simulations. Realistic numbers of the secondary particle yield, referring to existing state-of-the-art set-ups and a discussion of the feasibility of the experiment taking into account the background signal are presented.

We present the design of a photon-photon collider based on conventional Compton gamma sources for the observation of elastic γγ scattering. Two symmetric electron beams, generated by photocathodes and accelerated in linacs, produce two primary gamma rays through Compton backscattering with two high energy lasers. The elastic photon-photon scattering is analyzed by start-to-end simulations from the photocathodes to the detector. A new Monte Carlo code has been developed ad hoc for the counting of the QED events. Realistic numbers of the secondary gamma yield, obtained by using the parameters of existing or approved Compton devices, a discussion of the feasibility of the experiment and of the nature of the background are presented.

A previously healthy 20-year-old African-Canadian woman presented to the emergency department with blurred vision in her right eye for 3 days and a 6-week history of new-onset headaches, which had worsened substantially over the previous week. The patient also had transient vision blackouts that lasted seconds and occurred with changes in position, along with pulsatile tinnitus. She had gained 9 kg over the past 2 months. She was not taking vitamin A derivatives or tetracyclines. Idiopathic intracranial hypertension is a syndrome of raised intracranial pressure with no identifiable cause, such as vitamin A derivatives or tetracyclines, and is typically seen in young, obese women.1 Although patients usually present with chronic symptoms such as headache or incidentally discovered optic disc edema, idiopathic intracranial hypertension may have a fulminant course with rapid onset of symptoms.

A previously healthy 31-year-old woman presented to the ophthalmology clinic with a 2-month history of left ptosis. She also reported a dry cough, non-exertional dyspnea and anhidrosis on the left side of her face. On examination, her vital signs were normal, and she had mild left ptosis and anisocoria, which was worse in dim lighting conditions, with a smaller left pupil. The patient was also found to have bulkiness throughout the left cervical and supraclavicular area, diminished breath sounds and dullness to percussion on the left. Horner syndrome, also known as oculosympathetic paresis, is a result of disruption of the sympathetic pathway that begins in the hypothalamus and takes a long course down the spinal cord to C8-T2, courses around the apex of the lung and ascends with the internal carotid artery before entering the orbit.

Large numbers of stroke patients arrive at hospital at a very early stage, and effective treatments for the acute phase of the disease are available. However, evidence that patients with acute stroke benefit from stroke-unit care is scarce. Our aim was to determine whether admission to a stroke unit, rather than a conventional ward, affected the outcome of patients with acute stroke. We did an observational follow-up study of 11 572 acute stroke patients hospitalised within 48 h of the onset of symptoms either in a stroke unit (n=4936) or in a conventional ward (6636). Patients were identified retrospectively from discharge records from 260 Italian hospitals. The primary outcome was mortality or disability (Rankin score greater than two), assessed prospectively by independent, masked assessors 2 years after admission. Analyses were adjusted for patient characteristics and clustered at the hospital level. Overall, 1576 patients died in hospital; 2169 died during the follow-up period. 347 patients were lost to follow-up. Compared with conventional-ward care, stroke-unit care was associated with a reduced probability of death or being disabled at the end of follow-up (odds ratio 0·81, 95% CI 0·72–0·91; p=0·0001). The potential benefit was significant across all age ranges and clinical characteristics, except for unconsciousness. No specific elements of setting, organisation, or process of care were associated with outcome. Admission to a stroke-unit ward with dedicated beds and staff within 48 h of onset should be recommended for all patients with acute stroke.

Aedes albopictus (Diptera: Culicidae) is an invasive mosquito, native to Asia, that has expanded its range worldwide. It is considered to be a public health threat as it is a competent vector of viruses of medical importance, including dengue, chikungunya, and Zika. Despite its medical importance there is almost no information on biologically important traits of Ae. albopictus in Argentina. We studied life cycle traits, demographic parameters and analyzed the competence of this mosquito as a virus vector. In addition, we determined the prevalence of Wolbachia strains in Ae. albopictus as a first approach to investigate the potential role of this bacteria in modulating vector competence for arboviruses. We observed low hatch rates of eggs, which led to a negative growth rate. We found that Ae. albopictus individuals were infected with Wolbachia in the F1 but while standard superinfection with w AlbA and w AlbB types was found in 66.7% of the females, 16.7% of the females and 62.5% of the males were single-infected with the w AlbB strain. Finally, despite high levels of infection and dissemination, particularly for chikungunya virus, Ae. albopictus from subtropical Argentina were found to be relatively inefficient vectors for transmission of both chikungunya and dengue viruses.

To outline features of the neurologic examination that can be performed virtually through telemedicine platforms (the virtual neurological examination [VNE]), and provide guidance for rapidly pivoting in-person clinical assessments to virtual visits during the COVID-19 pandemic and beyond. The full neurologic examination is described with attention to components that can be performed virtually. A screening VNE is outlined that can be performed on a wide variety of patients, along with detailed descriptions of virtual examination maneuvers for specific scenarios (cognitive testing, neuromuscular and movement disorder examinations). During the COVID-19 pandemic, rapid adoption of virtual medicine will be critical to provide ongoing and timely neurological care. Familiarity and mastery of a VNE will be critical for neurologists, and this article outlines a practical approach to implementation.

Aedes aegypti (L.) (Diptera: Culicidae) is a vector of many medically significant viruses in the Americas, including dengue virus, chikungunya virus, and Zika virus.Traits such as longevity, fecundity, and feeding behavior contribute to the ability of Ae. aegypti to serve as a vector of these pathogens. Both local environmental factors and population genetics could contribute to variability in these traits. We performed a comparative study of Ae. aegypti populations from four geographically and environmentally distinct collection sites in Argentina in which the cohorts from each population were held at temperature values simulating a daily cycle, with an average of 25°C in order to identify the influence of population on life-history traits. In addition, we performed the study of the same populations held at a daily temperature cycle similar to that of the surveyed areas. According to the results, Aguaray is the most outstanding population, showing features that are important to achieve high fitness. Whereas La Plata gathers features consistent with low fitness. Iguazu was outstanding in blood-feeding rate while Posadas's population showed intermediate values. Our results also demonstrate that climate change could differentially affect unique populations, and that these differences have implications for the capacity for Ae. aegypti to act as vectors for medically important arboviruses.