We report the first observation of a large (more than 10%) reflectance anisotropy on a Ag(l 10) single crystal. We reproduce the experimental data fairly well by use of a theoretical model, based on the quasistatic approximation, which takes into account both the actual geometry of the crystal surface and the interband and intraband transitions. This demonstrates that the main effect is the screened surface local-field effect on resonant dipolar oscillations localized near the surface.PACS numbers: 78.66. Bz, 73.20.Mf, 78.20.Ci The symmetry of crystal surfaces has been shown to have a great influence on the physical and chemical properties of materials [1][2][3]. It is therefore of crucial interest to reach the surface properties of crystals by means of nondestructive techniques which can be applied in environments other than vacuum, such as gas or liquids. Reflectance difference spectroscopy (RDS) is a powerful tool for studying semiconductor surfaces [4,5] and monitoring semiconductor crystal growth, even in a gas atmosphere [6]. However, up to now, metal surfaces have not been investigated by RDS, although anisotropy effects have been observed on (110) surfaces of single Ag crystals by electroreflectance [7,8] and by electron energy loss spectroscopy experiments [9], and the dispersion relation of surface plasmons has been shown to depend on the direction of propagation along the surface [8,9].In this Letter we present an experimental and theoretical investigation of the optical reflectance of Ag(l 10). In particular, we report the first experimental observation by RDS of an anisotropy in the optical reflectance of the Ag(l 10) surface, the size of which is larger than that of semiconductor surfaces by 1 to 2 orders of magnitude [4,10,11]. We also reproduce fairly well the experimental reflectance anisotropy (RA) with a theoretical model which takes into account both d and s-p electron transitions, as well as the crystalline geometry of the (110) surface [12]. This large optical anisotropy originates from resonances in the surface conductivities, which are found to be different for the two principal symmetry directions of the (110) surface.The Ag single crystals were disks of 8 mm diameter and 2 mm thickness, cut from the same crystal rod by electroerosion. They were oriented by Laue x-ray back diffraction and mechanically polished to a mirrorlike finish using successively finer grades of diamond polishing suspension down to 0.25 jirn. Then they were chemically polished using a well-established chromium trioxide/hydrochloric acid etching procedure described previously [13]. This chemical treatment results in the selective dissolution of the cold-rolling layer formed during the mechanical polishing and was shown to provide welldefined single crystal Ag surfaces by capacitance and scanning tunneling microscopy studies [13]. The real and imaginary parts of the RAAr/r -(/•[,j 0 ] -r[ooi])/nooiJ were measured with a commercial RDS instrument, developed by ISA Jobin-Yvon Company (France). /*[n 0 ] and nooi] are t...

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Introduction: Determination of antinuclear antibodies (ANA) by indirect immunofluorescence (IIF) is usually the initial test for the diagnosis of systemic rheumatic diseases (SRD). Assigning predictive values to positive and negative results of the test is vital because lack of knowledge about ANAs and their usefulness in classification criteria of SRD leads to inappropriate use. Methods: Retrospective study, ANA tests requested by different specialties, correlation to patients' final diagnosis. Results: The prevalence of autoimmune disease was relatively low in our population yielding a low PPV and a high NPV for the ANA test. 40% of the patients had no clinical criteria applied prior to test. Coexistence of two or more autoimmune disorders affects prevalence and predictive values. Conclusion: Application of the test after careful evaluation for clinical criteria remarkably improves the positive likelihood ratio for the diagnosis.

Summary:Rapid prototyping models (RPMs) had been extensively used in craniofacial and maxillofacial surgery, especially in areas such as orthognathic surgery, posttraumatic or oncological reconstructions, and implantology. Economic limitations are higher in developing countries such as Mexico, where resources dedicated to health care are limited, therefore limiting the use of RPM to few selected centers. This article aims to determine the dimensional error of a low-cost fused deposition modeling 3D printer (Tronxy P802MA, Shenzhen, Tronxy Technology Co), with Open source software. An ordinary dry human mandible was scanned with a computed tomography device. The data were processed with open software to build a rapid prototype with a fused deposition machine. Linear measurements were performed to find the mean absolute and relative difference. The mean absolute and relative difference was 0.65 mm and 1.96%, respectively (P = 0.96). Low-cost FDM machines and Open Source Software are excellent options to manufacture RPM, with the benefit of low cost and a similar relative error than other more expensive technologies.

Upper extremity trauma encompasses a wide range of clinical presentations, from simple lacerations to catastrophic injuries that require extensive or multiple reconstructive procedures. The clear understanding of the trauma mechanisms and how they are related with certain patterns of injury might maximize awareness and guide a surgeon's management effectively.

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Background: Airway management in patients with Moebius syndrome can be difficult due to the presence of orofacial malformations. This paper aims to present our institution's experience in the evaluation and management of the upper airway in patients with Moebius syndrome Methodology: The authors performed a retrospective study including every patient with Moebius syndrome submitted to surgery between 2012 and 2017. Difficult airway was defined as one requiring more than 2 attempts to achieve endotracheal tube placement, a Mallampati score equal or above III, a Cormack score equal or above III, or need of a fiberscope during intubation. Results: Fifty-one patients were included, (39.3% males) requiring 172 procedures. Each patient required an average of 3.37 ± 1.94 anesthetic events. Average Body Mass Index (BMI) was 20.07 ± 6.06, 45.1% were overweight or obese. Four patients (7%) were considered as having a potentially difficult airway. Endotracheal intubation was achieved in all patients; 38 patients were intubated in a single attempt, while the rest were successfully intubated on a second try. Fiberscope was not necessary. Univariate analysis showed that overweight/obese patients were more likely to be considered as having a difficult airway (P = 0.03). Conclusion: Intubation can be difficult in patients with Moebius syndrome, but failure is rare. Overweight or obese patients are at risk of presenting a difficult airway. An extensive preoperative evaluation and adequate communication between the members of the multidisciplinary team in charge of these patients is paramount.

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