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Purpose 3D-printed porous metal scaffolds are a promising emerging technology in orthopedic implant design. Compared to solid metal implants, porous metal implants have lower magnetic susceptibility values, which have a direct impact on imaging time and image quality. The purpose of this study is to determine the relationship between porosity and effective susceptibility through quantitative estimates informed by comparing coregistered scanned and simulated field maps. Methods Five porous scaffold cylinders were designed and 3D-printed in titanium alloy (Ti-6Al-4V) with nominal porosities ranging from 60% to 90% using a cellular sheet-based gyroid design. The effective susceptibility of each cylinder was estimated by comparing acquired B0 field maps against simulations of a solid cylinder of varying assigned magnetic susceptibility, where the orientation and volume of interest of the simulations was informed by a custom alignment phantom. Results Magnitude images and field maps showed obvious decreases in artifact size and field inhomogeneity with increasing porosity. The effective susceptibility was found to be linearly correlated with porosity (R2 = 0.9993). The extrapolated 100% porous (no metal) magnetic susceptibility was −9.9 ppm, closely matching the expected value of pure water (−9 ppm), indicating a reliable estimation of susceptibility. Conclusion Effective susceptibility of porous metal scaffolds is linearly correlated with porosity. Highly porous implants have sufficiently low effective susceptibilities to be more amenable to routine imaging with MRI.

Calcium sulphate is an established carrier for localized drug delivery, but a means to non-invasively measure drug release, which would improve our understanding of localized delivery, remains an unmet need. We aim to quantitatively estimate the diffusion-controlled release of small-molecules loaded into a calcium sulphate carrier through gadobutrol-based contrast agent, which acts as a surrogate small-molecule. A central cylindrical core made of calcium sulphate, either alone or within a metal scaffold, is loaded with contrast agent that releases into agar. Multi-echo scans are acquired at multiple time-points over 4 weeks and processed into R2* and QSM maps. Mean R2*values are fit to a known drug delivery model, which are then compared to the decrease in core QSM. Fitting R2* measurements of calcium sulphate core while constraining constants to a drug release model results in a R2-value of 0.991, yielding a diffusion constant of 4.59x10-11 m2/s. Incorporating the carrier within a metal scaffold results in a slower release. QSM shows the resulting loss of susceptibility in the non-metal core but is unreliable around metal. R2* characterizes gadobutrol release and QSM detects the resulting decrease in susceptibility. The addition of a porous metal scaffold slows the release of gadobutrol, as expected.

Background:As of the 25th of January 2021, more than 150 thousand deaths as consequence of COVID-19 have been reported in Mexico [1]. Advanced age, male gender and comorbidities have been described as risk factors for severe disease and mortality in general population [2]. COVID-19 mortality in Mexican patients with rheumatic and musculoskeletal diseases (RMDs) is unknown.Objectives:To describe characteristics of Mexican patients with RMDs and COVID-19, and to analyse factors associated with mortality.Methods:The Global Rheumatology Alliance COVID-19 (GRA) physician reported registry, is an international effort to collect information on COVID19 in adult patients with RMDs. GRA is an observational registry. The first patient from Mexico was registered on April 17, 2020. All Mexican patients registered in GRA until October 30, 2020 were included in this analysis. The association of mortality with demographic and clinical variables was estimated using logistic regression analysis.Results:A total of 323 patients were registered, with a median age of 52 (IQR 41-61) years old, 166 (51.4%) patients lived in Mexico City. The most frequent RMDs were rheumatoid arthritis, 149 (46.1%) and systemic lupus erythematosus, 24 (19.8%). Over a third of patients with RMDs and COVID-19 (119 (36.8%)) were hospitalized, and 43 (13.3%) died. Table 1 shows clinical and demographic characteristics. In the univariable analysis, the absence of comorbidities was a protective factor, OR 0.3 (95% CI 0.1-0.6). Factors associated with mortality at COVID-19 diagnosis were age over 65 years old, having type 2 diabetes, chronic renal insufficiency, treatment at COVID-19 diagnosis with corticosteroids or with CD20 inhibitors. In the multivariable adjusted analysis, these factors remained independently associated with mortality. No associations with other treatments or comorbidities at COVID-19 diagnosis were found.Conclusion:Mexican patients with RMDs and COVID-19 in the GRA physician reported registry had a mortality of 13.3%. Factors associated with mortality were those described in the general population, such as older age and being on corticosteroids and CD20 inhibitors treatment at COVID-19 diagnosis.References:[1]WHO. Coronavirus disease (COVID-19) pandemic. https://www.who.int/emergencies/diseases/novel-coronavirus-2019. (accessed 26 January, 2021).[2]Zhou F, et al. Lancet 2020;395(10229):1054-62.Table 1.Clinical and demographic characteristics of patients with rheumatic diseases and COVID-19 in Mexico and mortality.Characteristics at COVID-19 diagnosisTotalN=323Death43 (13.3)Survivors280 (86.7)UnivariableOR (95% CI)MultivariableOR (95% CI)Women, n(%)268 (82.9)33 (76.7)235 (83.9)0.6 (0.3-1.4)0.5 (0.2-1.3)Age >65 years old, n(%)62 (19.2)18 (41.9)44 (15.7)3.9 (1.9-7.7)3.9 (1.9-8.3)RMDs* n(%)-Rheumatoid arthritis149 (46.1)23 (53.5)126 (45.0)1.6 (0.7-3.7)-Systemic Lupus Erythemathosus64 (19.8)10 (23.3)54 (19.3)1.6 (0.6-4.3)-Spondyloarthritis (axial and others)33 (10.2)2 (4.7)31 (11.1)0.1 (0.1-2.8)-Others77 (23.8)8 (18.6)69 (24.6)1-Moderate/High disease activity1, n(%)57 (18.6)7 (17.9)50 (18.7)1.0 (0.4-2.5)-None comorbidities, n(%)136 (42.1)8 (18.6)128 (45.7)0.3 (0.1-0.6)-Hypertension*, n(%)88 (27.2)12 (27.9)76 (27.1)1.0 (0.5-2.1)-Type 2 Diabetes*, n(%)49 (15.2)13 (30.2)36 (12.9)2.9 (1.4-6.1)2.4 (1.1-5.4)Obesity*, n(%)21 (6.5)3 (6.9)18 (6.4)1.1 (0.3-3.9)-Chronic obstructive pulmonary disease*, n(%)15 (4.6)1 (2.3)14 (5.0)0.5 (0.1-3.5)-Chronic renal insufficiency*, n(%)17 (5.2)6 (13.9)11 (3.9)3.9 (1.4-11.4)3.4 (1.1-10.4)Cardiovascular diseases*, n(%)14 (4.3)2 (4.7)12 (4.3)1.1 (0.2-5.0)-Corticosteroids*, n(%)171 (52.9)30 (69.7)141 (50.3)2.3 (1.1-4.5)3.0 (1.4-6.5)CsDMARD*, n(%)247 (76.5)33 (16.3)214 (76.4)1.0 (0.5- 2.2)-CD20 inhibitor*, n(%)21 (6.5)7 (16.3)14 (5.0)3.7 (1.4-9.9)4.9 (1.7-14.5)*Overlapped, 1 307 patients.Disclosure of Interests:None declared

Inherently multi-mode evolution of isolated defects, such as straight grooves and axisymmetric dots on planar laser targets, is studied theoretically. The development of perturbations is considered for a propagating rippled shock front, a material interface subject to the classical Richtmyer–Meshkov instability (RMI), a rippled rarefaction wave produced by the feedout process, an ablation front subject to the ablative RMI, and a thin fluid layer subject to the classical Rayleigh–Taylor instability (RTI). For the small-amplitude regime, we have established specific characteristics of the perturbation evolution initiated with such defects, scaling, and conservation laws governing it. The main features of the nonlinear growth of the classical and ablative RTI starting from isolated defects are the lateral expansion of the bubbles and the oblique with respect to the direction of the acceleration, ejection of spikes. It results in filling up the void left from the bubble growth by the laterally converging spike material. This effect, first discovered in simulations by Dahlburg et al. [Phys. Fluids B 5, 571 (1993)], and very recently observed by Zulick et al. [Phys. Rev. Lett. 125, 055001 (2020)], is captured by the appropriate modification of the Ott–Basko thin-layer classical RTI theory for arbitrary defect profiles. Predictions for novel hydrodynamic experiments on multi-mode hydrodynamic perturbation evolution are presented.

When a planar shock hits a corrugated contact surface between two fluids, hydrodynamic perturbations are generated in both fluids that result in asymptotic normal and tangential velocity perturbations in the linear stage, the so called Richtmyer-Meshkov instability. In this work, explicit and exact analytical expansions of the asymptotic normal velocity (δv_{i}^{∞}) are presented for the general case in which a shock is reflected back. The expansions are derived from the conservation equations and take into account the whole perturbation history between the transmitted and reflected fronts. The important physical limits of weak and strong shocks and the high/low preshock density ratio at the contact surface are shown. An approximate expression for the normal velocity, valid even for high compression regimes, is given. A comparison with recent experimental data is done. The contact surface ripple growth is studied during the linear phase showing good agreement between theory and experiments done in a wide range of incident shock Mach numbers and preshock density ratios, for the cases in which the initial ripple amplitude is small enough. In particular, it is shown that in the linear asymptotic phase, the contact surface ripple (ψ_{i}) grows as ψ_{∞}+δv_{i}^{∞}t, where ψ_{∞} is an asymptotic ordinate different from the postshock ripple amplitude at t=0+. This work is a continuation of the calculations of F. Cobos Campos and J. G. Wouchuk, [Phys. Rev. E 90, 053007 (2014)PLEEE81539-375510.1103/PhysRevE.90.053007] for a single shock moving into one fluid.

The influence of glass covering on domain wall propagation in Fe 65 B 15 Si 15 C 5 amorphous microwires is studied, before and after glass removal. High values of domain wall velocity and mobility have been obtained. The domain wall velocity depends linearly on the driving magnetic field. However, the mobility of the domain wall is very different in both situations studied. The results are explained due to the modification of internal stress distribution after glass removing, that change the domain structure of the sample.

An analytical model to study the perturbation flow that evolves between a rippled piston and a shock is presented. Two boundary conditions are considered: rigid and free surface. Any time a corrugated shock is launched inside a fluid, pressure, velocity, density, and vorticity perturbations are generated downstream. As the shock separates, the pressure field decays in time and a quiescent velocity field emerges in the space in front of the piston. Depending on the boundary conditions imposed at the driving piston, either tangential or normal velocity perturbations evolve asymptotically on its surface. The goal of this work is to present explicit analytical formulas to calculate the asymptotic velocities at the piston. This is done in the important physical limits of weak and strong shocks. An approximate formula for any shock strength is also discussed for both boundary conditions.

Measurements made on the components and on two assembled systems of a 2-m Ritchey-Chretien telescope have been used to determine the actual characteristics of the telescope. Sufficient precision has been obtained so that other focal ratio systems can be designed.

A formula is derived from meridional ray tracing for finding the refractive-index of a lens in terms of its construction parameters. Also, an experimental technique is presented as well as its accuracy for the determination of the refractive-index of the lens for the wavelength of a He-Ne laser (6328 A).

In this paper we present the Medium Resolution Spectrograph ESOPO, an instrument designed and built for the 2.1m Telescope at the Observatorio Astronomico Nacional at San Pedro Martir. We discuss the Scientific Goals and the High Level Requirements necessary to translate these goals to optical, mechanical and control specifications. We make an introduction to its conceptual dual-arm design. The optical design is based on a non-classical configuration. The gratings are illuminated in a conical mode working in a quasi Littrow configuration which has the advantage of optimizing the efficiency and the pupil area on the grating. We show here the results of an experimental evaluation of the concept. The optical design, mechanical structure, slit-mask and acquisition system, control systems, and a study of thermal compensators, are discussed briefly, references to more extended contributions in these proceedings are made. The management schematics of the project are briefly discussed.

This work presents the specifications, requirements, design, finite element analysis and results of the assembled subsystems: slit-mask, and the acquisition and guiding zone mechanisms of the ESOPO spectrograph. This spectrograph is a project of the Institute of Astronomy, National University of Mexico.

ESOPO will be a spectrograph of medium resolution for the 2.1 m telescope of the National Observatory at San Pedro Martir, Baja California, Mexico. It has been developed by the Instituto de Astronomia of the Universidad Nacional Autonoma de Mexico (IA-UNAM). The main goal of this instrument is to modernize the capabilities of making science with that particular telescope. It is planned to achieve a spectral resolution between 500 and 5000. ESOPO is split into two arms; each one specialized in a specific wavelength range covering together all the visible light. A very important issue in spectrographs is to avoid inside thermal gradients. Different temperatures in the optical elements produce mechanical movements and image quality degradation during an exposition. The error budget analysis developed for ESOPO allows establishing the required limits for temperature gradients. In this paper is described the thermal analysis of the spectrograph, including specifications, finite element models, thermal equations and expected thermal gradients.

OSIRIS is the optical Day 1 instrument for the 10.4 m GTC telescope. OSIRIS will cover the 365 to 1000 nm spectral range, featuring an 8.6×8.6 arcmin field of view, and capabilities for direct imaging, both long-slit and multiple object spectroscopy, and fast spectrophotometry. The combination of OSIRIS wide field, tunable filters plus charge shuffling array detectors, will constitute the most powerful instrument for studying faint emission-line sources at any redshift. The present contribution gives an overview of the instrument development, currently in its verification phase before commissioning on site. © 2007 Springer.

In March 2004, the Commissioning Instrument (CI) for the GTC was accepted in the site of The Gran Telescopio Canarias (GTC) located in La Palma Island, Spain. During the GTC integration phase, the CI will be a diagnostic tool for performance verification. The CI features four operation modes-imaging, pupil imaging, Curvature Wave-front sensing (WFS), and high resolution Shack-Hartmann WFS. The imaging mode permits to qualify the GTC image quality. The Pupil Mode permits estimate the GTC stray light. The segments figure, alignment and cophasing verifications are made with both WFS modes. In this work we describe the Commissioning Instrument and show some tests results obtained during the site acceptance process at the GTC site.

In March 2004 was accepted in the site of Gran Telescopio Canarias (GTC) in La Palma Island, Spain, the Commissioning Instrument (CI) for the GTC. During the GTC integration phase, the CI will be a diagnostic tool for performance verification. The CI features four operation modes-imaging, pupil imaging, Curvature Wave-front sensing (WFS), and high resolution Shack-Hartmann WFS. This instrument was built by the Instituto de Astronomia UNAM in Mexico City and the Centro de Ingenieria y Desarrollo Industrial (CIDESI) in Queretaro, Qro under a GRANTECAN contract after an international public bid. Some optical components were built by Centro de Investigaciones en Optica (CIO) in Leon Gto and the biggest mechanical parts were manufactured by Vatech in Morelia Mich. In this paper we made a general description of the CI and we relate how this instrument, build under international standards, was entirely made in Mexico.

"OSIRIS (Optical System for Imaging and low Resolution Integrated Spectroscopy) is the optical Day one instrument for the GTC and the only Spanish Day One instrument. With both instrument and telescope schedules matched, OSIRIS will be available as soon as the GTC is scientifically operational. In this contribution an overview of the instrument at the middle of 2004 is given."

We investigate the role of industrial replication in the construction of the next generation of spectrographs for large telescopes. In this paradigm, a simple base spectrograph unit is replicated to provide multiplex advantage, while the engineering costs are amortized over many copies. We argue that this is a cost-effective approach when compared to traditional spectrograph design, where each instrument is essentially a one-off prototype with heavy expenditure on engineering effort. As an example of massive replication, we present the design of, and the science drivers for, the Visible IFU Replicable Ultra-cheap Spectrograph (VIRUS). This instrument is made up of 132 individually small and simple spectrographs, each fed by a fiber integral field unit. The total VIRUS-132 instrument covers ~29 sq. arcminutes per observation, providing integral field spectroscopy from 340 to 570 nm, simultaneously, of 32,604 spatial elements, each 1 sq. arcsecond on the sky. VIRUS-132 will be mounted on the 9.2 m Hobby-Eberly Telescope and fed by a new wide-field corrector with a science field in excess of 16.5 arcminutes diameter. VIRUS represents a new approach to spectrograph design, offering the science multiplex advantage of huge sky coverage for an integral field spectrograph, coupled with the engineering multiplex advantage of >102 spectrographs making up a whole.

A Camera Barrel, located in the OSIRIS imager/spectrograph for the Gran Telescopio Canarias (GTC), is described in this article. The barrel design has been developed by the Institute for Astronomy of the University of Mexico (IA-UNAM), in collaboration with the Institute for Astrophysics of Canarias (IAC), Spain. The barrel is being manufactured by the Engineering Center for Industrial Development (CIDESI) at Queretaro, Mexico. The Camera Barrel includes a set of eight lenses (three doublets and two singlets), with their respective supports and cells, as well as two subsystems: the Focusing Unit, which is a mechanism that modifies the first doublet relative position; and the Passive Displacement Unit (PDU), which uses the third doublet as thermal compensator to maintain the camera focal length and image quality when the ambient temperature changes. This article includes a brief description of the scientific instrument; describes the design criteria related with performance justification; and summarizes the specifications related with misalignment errors and generated stresses. The Camera Barrel components are described and analytical calculations, FEA simulations and error budgets are also included.

We present the dual IR camera CID for the 2.12 m telescope of the Observatorio Astronomico Nacional de Mexico, IA-UNAM. The system consists of two separate cameras/spectrographs that operate in different regions of the IR spectrum. In the near IR, CID comprises a direct imaging camera with wide band filters, a CVF, and a low resolution spectrograph employing an InSb 256 x 256 detector. In the mid IR, CID uses a BIB 128 x 128 detector for direct imaging in 10 and 20 microns. Optics and mechanics of CID were developed at IR-Labs (Tucson). The electronics was developed by R. Leach (S. Diego). General design, construction of auxiliary optics (oscillating secondary mirror), necessary modifications and optimization of the electronics, and acquisition software were carried out at OAN/ UNAM. The compact design of the instruments allow them to share a single dewar and the cryogenics system.

OSIRIS (Optical System for Imaging and low Resolution Integrated Spectroscopy) is the optical Day One instrument for the 10.4m Spanish telescope GTC to be installed in the Observatorio del Roque de Los Muchachos (La Palma, Spain). This instrument, operational in mid-2004, covers from 360 up to 1000 nm. OSIRIS observing modes include direct imaging with tunable and conventional filters, long slit and multiple object spectroscopy and fast spectrophotometry. The OSIRIS wide field of view, high efficiency and the new observing modes (tunable imaging and fast spectrophotometry) for 8-10m class telescopes will provide GTC with a powerful tool for their scientific exploitation. The present paper provides an updated overview of the instrument development, of some of the scientific projects that will be tackled with OSIRIS and of the general requirements driving the optical and mechanical design.

We present the optical design of the f/1 camera for the Hobby-Eberly Telescope Low Resolution Spectrograph Infrared Extension (LRS-J). This instrument extends the coverage of the LRS to 1300 nm by adding a fast cryogenic camera and volume holographic grisms (VPHG) to the LRS. This approach enables new science without the expense of building a complete new instrument. The camera is a catadioptric Maksutov type design, based on that of the optical LRS, that uses a HAWAII-1 1024x1024 detector. The design succeeds in imaging virtually all the light into one pixel over the HET field of view (FOV) and the wavelength range 900-1300 nm. We discuss the challenges of designing and manufacturing a fast camera for cryogenic use, and give details of the tolerance analysis.

During the GTC integration phase, the Commissioning Instrument (CI) will be a diagnostic tool for performance verification. The CI features four operation modes-imaging, pupil imaging, Curvature WFS, and high resolution Shack-Hartmann WFS. After the GTC Commissioning we also plan to install a Pyramid WFS. This instrument can therefore serve as a test bench for comparing co-phasing methods for ELTs on a real segmented telescope. In this paper we made a general instrument overview.

to document the usefulness of self-expanding metal stents in patients with malignant dysphagia.from January 1992 to January 1997 we implanted 75 Wallstent prostheses (28 uncovered AV, 20 uncovered Unistep, 15 covered Telestep, and 2 covered double-mesh Permalume stents) in 65 patients with malignant dysphagia.mean survival time was 100 days in patients with uncovered stents, and 215 days in patients with covered stents. Oral feeding was possible throughout the post-implantation course in 58 of 65 patients. Only two severe complications occurred: esophageal perforation with mediastinitis, and migration of the stent from the distal esophagus into the stomach. All implantation procedures were done under radiological guidance. For AV and Unistep prostheses we used a nasal approach without sedation, and for Telestep and Permalume stents we used an oral approach with sedation.Wallstent self-expanding metal stents are useful in palliating malignant dysphagia. The placement and implantation of these stents are straightforward.

The geriatric population consumes greater numbers of medicines than other age groups. We compared drug prescription and consumption in elderly persons residing in a nursing home or living in their own home.We studied 366 elderly men and women (older than 65 years) who lived either in nursing homes or in their own home. The variables recorded were the most frequent diseases, number and types of drugs prescribed per person, and adverse reactions of the most frequently prescribed drugs.The most common diseases recorded among subjects living at home were arterial hypertension and rheumatic diseases; among those in nursing homes, the most common ailment was dementia. Subjects in nursing homes were prescribed more different drugs (2.8 +/- 1/person) than individuals living on their own (1.8 +/- 1/person). The percentage of adverse reactions was highest in ambulatory patients (64%) and in patients taking benzodiazepines (56%). A large proportion of all prescriptions (74.5%) were for solid galenic forms.We draw attention to the greater consumption of drugs by elderly persons residing in nursing homes, as well as the prescription of benzodiazepines and analgesic-antiinflammatory drugs within old age.

We describe recent advances in the development of a scanning Fabry-Perot interferometer applied to the study of the kinematics of the interstellar medium at the Observatorio Astronómico Nacional at San Pedro Mártir, B.C. México.

The Optical System for Imaging and low Resolution Integrated Spectroscopy (OSIRIS) has been designed as a Day-One optical instrument for the 10.4-m Gran Telescopio Canarias (GTC). Its conceptualization started as early as 1998. This contribution summarizes how the evolution of the OSIRIS concept forced the optical design to successfully respond to ever-harder challenges. It will be the first instrument, on such a large telescope, belonging to a new class of tunable imager, using tunable filters (TFs), and a single slit and multi-object low-resolution spectrograph. These features combined with charge shuffling capabilities, covering the optical wavelength range (365-1000 nm). OSIRIS, to be first mounted at one of GTC's Nasmyth platforms, is designed to be compact enough to fit at the Cassegrain focus as well. The optical design is devised around the classical concept of collimator plus camera. The collimator is an off axis ellipsoidal mirror, while the f/2.475 camera consists of several groups of all spherical surfaces lenses, forming a unit together with the detector and cryocooler. A folder mirror prevents interference with the GTC acquisition and guiding subsystem. Several combinations of color and interference filters, TFs and grisms are available in the collimated beam, near the pupil, to provide the wide versatility of required observing modes and resolutions. Short descriptions of the OSIRIS geometry, specifications and the optical design are presented, with emphasis in the strategy followed in the design process.