Automatic Zig-Zag sampling in practice

Novel Monte Carlo methods to generate samples from a target distribution, such as a posterior from a Bayesian analysis, have rapidly expanded in the past decade. Algorithms based on Piecewise Deterministic Markov Processes (PDMPs), non-reversible continuous-time processes, are developing into their own research branch, thanks their important properties (e.g., correct invariant distribution, ergodicity, and super-efficiency). Nevertheless, practice has not caught up with the theory in this field, and the use of PDMPs to solve applied problems is not widespread. This might be due, firstly, to several implementational challenges that PDMP-based samplers present with and, secondly, to the lack of papers that showcase the methods and implementations in applied settings. Here, we address both these issues using one of the most promising PDMPs, the Zig-Zag sampler, as an archetypal example. After an explanation of the key elements of the Zig-Zag sampler, its implementation challenges are exposed and addressed. Specifically, the formulation of an algorithm that draws samples from a target distribution of interest is provided. Notably, the only requirement of the algorithm is a closed-form function to evaluate the target density of interest, and, unlike previous implementations, no further information on the target is needed. The performance of the algorithm is evaluated against another gradient-based sampler, and it is proven to be competitive, in simulation and real-data settings. Lastly, we demonstrate that the super-efficiency property, i.e. the ability to draw one independent sample at a lesser cost than evaluating the likelihood of all the data, can be obtained in practice.Comment: Small edits from previous version following some minor revisions requeste

Lipoma Intraóseo

Se comunica un caso clínico de Lipoma Intraóseo de tibia con diagnóstico anatomopatológico confirmado, que constituye en la revisión bibliográfica el número 35. Se realiza, a propósito de este caso clínico, el estudio de otras lesiones con las que es obligado establecer el diagnóstico diferencial.The authors describe a medical case of Intrabone Tibial Lypoma with anatomical-patology confirmed that constitutes in the bibliografical revision numbe r 35. They realize, abolit this clinic case the review of other lesions with which they must establish the differential diagnosis

Exploring the protonation properties of photosynthetic phycobiliprotein pigments from molecular modeling and spectral line shapes

In photosynthesis, specialized light harvesting pigment- protein complexes (PPCs) are used to capture incident sunlight and funnel its energy to the reaction center. In Cryptophyte algae these complexes are suspended in the lumen, where the pH ranges between ~5-7, depending on the prolongation of the incident sunlight. However, the pKa of the several kinds of bilin chromophores encountered in these complexes and the effect of its protonation state on the energy transfer process is still unknown. Here, we combine quantum chemical and continuum solvent calculations to estimate the intrinsic aqueous pKas of different bilin pigments. We then use Propka and APBS classical electrostatic calculations to estimate the change in protonation free energies when the bilins are embedded inside five different phycobiliproteins (PE545, PC577, PC612, PC630 and PC645), and critically asses our results by analysis of the changes in the absorption spectral line shapes measured within a pH range from 4.0 to 9.4. Our results suggest that each individual protein environment strongly impacts the intrinsic pKa of the different chomophores, being the final responsible of their protonation state

Biofilm formation on dental implant surface treated by implantoplasty : an in situ study

Peri-implantitis is a biofilm-related disease whose characteristics are peri-implant tissues inflammation and bone resorption. Some clinical trials report beneficial effects after implantoplasty, namely the surgical smoothening of the implant surface, but there is a lack of data about the development of the bacterial biofilm on those smoothened surfaces. The aim of this study is to evaluate how implantoplasty influences biofilm formation. Three implants with moderately rough surfaces (control) and three implants treated with implantoplasty (test) were set on a tray reproducing the supra- and sub-gingival environment. One volunteer wore this tray for five days. Every 24 h, plaque coverage was measured and, at the end of the period of observartion, the implant surfaces were analyzed using scanning electron microscopy and confocal laser scanning microscopy. The proportion of implant surface covered with plaque was 65% (SD = 7.07) of the control implants and 16% (SD = 0) of the test implants. Untreated surfaces showed mature, complex biofilm structures with wide morphological diversity, and treated surfaces did not show the formation of mature biofilm structures. This study supports the efficacy of implantoplasty in reducing plaque adhesion and influencing biofilm formation. These results can be considered a preliminary proof of concept, but they may encourage further studies about the effects of implantoplasty on biofilm formation

Three cases of mcr-1-positive colistin-resistant Escherichia coli bloodstream infections in Italy, August 2016 to January 2017

We describe three cases of bloodstream infection caused by colistin-resistant Escherichia coli in patients in a tertiary hospital in Italy, between August 2016 and January 2017. Whole genome sequencing detected the mcr-1 gene in three isolated strains belonging to different sequence types (STs). This occurrence of three cases with mcr-1-positive E. coli belonging to different STs in six months suggests a widespread problem in settings where high multidrug resistance is endemic such as in Italy

Influence of Diabetes on Implant Failure and Peri-Implant Diseases: A Retrospective Study

Diabetes is an important modifying factor of periodontitis, but its association with peri-implant diseases has not been fully explored and the existing literature reports controversial results. The aim of this retrospective study was to evaluate the influence of diabetes on peri-implantitis and implant failure. Smoking status, history of periodontal disease, presence of diabetes, diabetes type, therapy and glycaemia levels were collected in a total of 204 subjects treated with 929 implants, with a mean follow-up time of 5.7 \ub1 3.82 years after loading. Odds ratio (OR) for diabetes as a direct cause of peri-implantitis and implant failure were calculated, adjusted for smoking status and history of periodontitis. Nineteen patients were diabetic and most of them presented a good control of the disease at the time of surgery. The overall patient-level prevalence of peri-implantitis was 11.3%. Among diabetic patients, one developed peri-implantitis, whereas one experienced multiple implant failures. The calculated ORs, adjusted for smoking status and periodontitis, were not statistically significant. The results revealed no association between diabetes and peri-implantitis or implant failure coherently with the existing scientific literature. The actual influence of hyperglycemia on implant failure is still uncertain and new studies with larger cohorts of patients are needed

Rf interference analysis in aperture synthesis interferometric radiometers: application to l-band miras instrument

Current spaceborne radiometers do not achieve the required spatial resolution demanded by the scientific community due to antenna-size technological limitations. In recent years, several space agencies have been studying aperture synthesis interferometric radiometers as a way of overcoming these limitations, which are more evident at low microwave frequencies (e.g., at L-band), where sea surface salinity and soil moisture can be monitored. Interference is an important issue in any remote sensing instrument, but it is crucial in microwave radiometers, since the signal being measured is the spontaneous thermal noise emission. Interference analyses already exist for classic radiometers. The objective of this paper is the analysis of RF interference on interferometric radiometers. The study involves the analysis of possible interference sources that may affect the performance of such systems at L-band: (1) nearby emissions from radars, non-Geo-Stationary Orbit (GSO) and Mobile Satellite Services (GSO-MSS), (2) harmonics of lower frequency emissions, and (3) possible jamming.Peer ReviewedPostprint (published version

Thirteenth Intercomparison Campaign of the Regional Brewer Calibration Center Europe: Lichtklimatisches Observatorium, Arosa, Switzerland: 30 July–10 August 2018

Editado por Alberto Redondas y Stoyka NetchevaThis thirteenth campaign was a joint exercise of the Regional Brewer Calibration Center for Europe (RBCC-E) and the Regional Dobson Calibration Center (RDCC-E) with the support of MeteoSwiss and of the Global Atmosphere Watch (GAW) Programme of the World Meteorological Organization (WMO). The following operations were performed by the RBCC-E during the intercomparison: Ozone calibration against the RBCC-E travelling reference (B#185) ; Compilation of the calibration histories of the instruments ; Evaluation of the Level 2 Eubrewnet ozone data for the period between intercomparisons

Deriving VTEC Maps from SMOS Radiometric Data

Special Issue Ten Years of Remote Sensing at Barcelona Expert Center.-- 18 pages,14 figures, 2 tablesIn this work, a new methodology is proposed in order to derive vertical total electron content (VTEC) maps from the radiometric measurements of the Soil Moisture and Ocean Salinity (SMOS) mission as an alternative approach to those based on external databases and models. This approach uses spatiotemporal filtering techniques with optimized filters to be robust against the thermal noise and image reconstruction artifacts present in SMOS images. It is also possible to retrieve the Faraday rotation angle from the recovered VTEC maps in order to correct the effect that it causes in the SMOS brightness temperaturesThis research was supported by the European Space Agency and Deimos Engenharia (Portugal), SMOS P7 Subcontract DME CP12 no. 2015-005; ERDF (European Regional Development Fund); by the Spanish public funds, projects TEC2017-88850-R and ESP2015-67549-C3-1-R; and through the award “Unidad de Excelencia María de Maeztu” MDM-2016-0600, financed by the “Agencia Estatal de Investigación” (Spain) and by the European Regional Development Fund (ERDF)With the funding support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S), of the Spanish Research Agency (AEI)Peer reviewe