General-purpose programmable photonic processor for advanced radiofrequency applications.

A general-purpose photonic processor can be built integrating a silicon photonic programmable core in a technology stack comprising an electronic monitoring and controlling layer and a software layer for resource control and programming. This processor can leverage the unique properties of photonics in terms of ultra-high bandwidth, high-speed operation, and low power consumption while operating in a complementary and synergistic way with electronic processors. These features are key in applications such as next-generation 5/6 G wireless systems where reconfigurable filtering, frequency conversion, arbitrary waveform generation, and beamforming are currently provided by microwave photonic subsystems that cannot be scaled down. Here we report the first general-purpose programmable processor with the remarkable capability to implement all the required basic functionalities of a microwave photonic system by suitable programming of its resources. The processor is fabricated in silicon photonics and incorporates the full photonic/electronic and software stack.

Programmable integrated photonics for topological Hamiltonians.

A variety of topological Hamiltonians have been demonstrated in photonic platforms, leading to fundamental discoveries and enhanced robustness in applications such as lasing, sensing, and quantum technologies. To date, each topological photonic platform implements a specific type of Hamiltonian with inexistent or limited reconfigurability. Here, we propose and demonstrate different topological models by using the same reprogrammable integrated photonics platform, consisting of a hexagonal mesh of silicon Mach-Zehnder interferometers with phase shifters. We specifically demonstrate a one-dimensional Su-Schrieffer-Heeger Hamiltonian supporting a localized topological edge mode and a higher-order topological insulator based on a two-dimensional breathing Kagome Hamiltonian with three corner states. These results highlight a nearly universal platform for topological models that may fast-track research progress toward applications of topological photonics and other coupled systems.

Modeling amplified arbitrary filtered heterodyne microwave photonic links.

We report an end-to-end analytic model for the computation of the figures of nerit (FOMs) of arbitrarily filtered and amplified heterodyne coherent microwave photonics (MWP) links. It is useful for evaluating the performance of complex systems where the final stage is employed for up/down-converting the radio frequency (RF) signal. We apply the model to a specific case of complex system representing the front-haul segment in a 5G link between the central office and the base station. The model can be however applied to a wider range of cases combining fiber and photonic chip elements and thus is expected to provide a useful and fast tool to analyze them in the design stage.

Modeling amplified arbitrary filtered microwave photonic links and systems.

Microwave photonic (MWP) links and systems will have more losses as their complexities increase and there will be a need for incorporating optical amplification. Here, we report results of an analytical model developed for amplified arbitrary filtered MWP systems that provides the expressions of the main figures of merit for intensity modulation direct detection. It contemplates the cases of power, intermediate and pre amplification. The model is applied to a long MWP link and then it is evaluated in a MWP reconfigurable filter implemented by means of a programmable waveguide mesh photonic integrated circuit.

Silicon nitride programmable photonic processor with folded heaters.

General-purpose programmable photonic processors rely on the large-scale integration of beamsplitters and reconfigurable phase shifters, distributed within unit cells or photonic gates. With their future evolution threatened by several hardware constrains, including the integration density that can be achieved with current mesh topologies, in this work, we present a unit cell topology design to increase the integration density of waveguide mesh arrangements based on folded Mach-Zehnder Interferometers. We report the design details of a 40-unit cell waveguide mesh integrated in a 11mm x 5.5 mm silicon nitride chip achieving, to the best of our knowledge, the highest integration density reported to date for a general-purpose photonic processor. The chip is electrically interfaced to a PCB and we report examples of reconfigurable optical beamsplitters, basic tunable microwave photonic filters with high peak rejection (40 dB approx.), as well as the dynamic interconnection and routing of 5G digitally modulated signals within the photonic mesh.

Multipurpose self-configuration of programmable photonic circuits.

Programmable integrated photonic circuits have been called upon to lead a new revolution in information systems by teaming up with high speed digital electronics and in this way, adding unique complementary features supported by their ability to provide bandwidth-unconstrained analog signal processing. Relying on a common hardware implemented by two-dimensional integrated photonic waveguide meshes, they can provide multiple functionalities by suitable programming of their control signals. Scalability, which is essential for increasing functional complexity and integration density, is currently limited by the need to precisely control and configure several hundreds of variables and simultaneously manage multiple configuration actions. Here we propose and experimentally demonstrate two different approaches towards management automation in programmable integrated photonic circuits. These enable the simultaneous handling of circuit self-characterization, auto-routing, self-configuration and optimization. By combining computational optimization and photonics, this work takes an important step towards the realization of high-density and complex integrated programmable photonics.

Integrated photonic tunable basic units using dual-drive directional couplers.

Photonic integrated circuits based on waveguide meshes and multibeam interferometers call for large-scale integration of Tunable Basic Units (TBUs) that feature beam splitters and waveguides. This units are loaded with phase actuators to provide complex linear processing functionalities based on optical interference and can be reconfigured dynamically. Here, we propose and experimentally demonstrate, to the best of our knowledge, for the first time, a thermally actuated Dual-Drive Directional Coupler (DD-DC) design integrated on a silicon nitride platform. It operates both as a standalone optical component providing arbitrary optical beam splitting and common phase as well as a low loss and potentially low footprint TBU. Finally, we report the experimental demonstration of the first integrated triangular waveguide mesh arrangement using DD-DC based TBUs and provide an extended analysis of its performance and scalability.

Bibliometric Analysis of Medication-Related Osteonecrosis of the Jaw: High Citation Rates but Low Evidence.

PURPOSE: Citation analysis is one of the most commonly used bibliometric tools for measuring the academic importance of a report in a specific area of knowledge. The objective of the present study was to identify the 100 most cited reports on medication-related osteonecrosis of the jaw (MRONJ), determine their main bibliometric characteristics, and identify the bibliometric variables that affected the citation rates. MATERIALS AND METHODS: We performed a data search in the Scopus database to determine the number of MRONJ article citations up to September 30, 2018. We next selected the 100 most referenced studies and recorded the following information: ranking according to the number of citations; citation density; number and names of authors; language and year of publication; country and institution of origin; financial support; journal name, impact factor, category, and quartile; type of research; evidence level; and area of study. RESULTS: The 100 most cited reports had a mean citation density of 21.7 ± 20.7 (range, 6.2 to 99.4) and an h-index of 96. The 100 most cited reports on MRONJ had been published in 42 scientific journals, classified into 10 separate categories of the Journal Citation Reports; 56% of the articles were in the first quartile of their category. Most of the studies had been classified with a level of evidence of 4 (n = 45) or 5 (n = 29). In the bivariate analyses, only the conflict of interest (P = .002) was associated with citation density. After adjusting for numerous variables, conflict of interest (r = 0.27; P = .020) and country of the first author (r = 0.23; P = .043) were significantly associated with citation density. CONCLUSIONS: The 100 most cited studies of MRONJ had a large number of citations and had been reported in journals with a high impact factor; however, the studies had a generally low evidence level and randomized clinical trials were lacking.

Knowledge About the Relation Between Tobacco and Disease and the Attitude Toward Advising the Cessation of Its Consumption Among a Group of Spanish Dental Students.

Tobacco is one of the leading causes of preventable death in the developed world. Smoking is associated with a large number of oral pathologies, such as cancer and periodontitis. Dental professionals can play a key role in preventing these health problems. The objectives of this study were (1) to analyze tobacco consumption habits among a group of Spanish dental students, and (2) to assess their knowledge, perceptions, and attitudes regarding procedures to help patients quit smoking. A cross-sectional descriptive study was carried out at the Faculty of Medicine and Dentistry of Santiago de Compostela (Galicia, Spain). Three validated questionnaires were distributed, and the obtained data was processed using SPSS. One hundred twenty out of 220 surveys were completed. Of the students, 18.3% were smokers and the average number of smoked cigarettes per day was 7.5. Tobacco dependence and the intention to give up the habit were low (Fagerström Test) and doubtful (Richmond test), respectively. The majority of students (94.2%) considered it appropriate to promote tobacco use cessation (TUC) activities. A great divergence of criteria regarding tobacco-associated pathologies was found among courses. This article provides positive data about the motivation of dental students to implement TUC strategies. Nevertheless, the usefulness of these interventions makes it necessary to modify the university curricula in order to improve the education on this issue to reduce the incidence of future health problems.

Surgically assisted rapid palatal expansion using customized bone-borne devices.

Correction of maxillary compression via palatal expansion is easy in children and adolescents, but more complicated once growth is finished. This correction may be performed by progressive expansion using orthopaedic appliances after osteotomy with more stable results, which facilitate a second phase to achieve larger expansions. We present a clinical case treated using a customized device that improves predictability. The stability of the device is ensured by multiple support points with 8 screws that fix it to the palate. Key words:Surgically assisted rapid palatal expansion, stereolithographic model, customized, bone-borne, expansion device.

Clinical value of diascopy and other non-invasive techniques on differential diagnosis algorithms of oral pigmentations: A systematic review.

OBJECTIVES: To determine the diagnostic value of diascopy and other non-invasive clinical aids on recent differential diagnosis algorithms of oral mucosal pigmentations affecting subjects of any age. MATERIAL AND METHODS: Data Sources: this systematic review was conducted by searching PubMed, Scopus, Dentistry & Oral Sciences Source and the Cochrane Library (2000-2015); Study Selection: two reviewers independently selected all types of English articles describing differential diagnosis algorithms of oral pigmentations and checked the references of finally included papers; Data Extraction: one reviewer performed the data extraction and quality assessment based on previously defined fields while the other reviewer checked their validity. RESULTS: Data Synthesis: eight narrative reviews and one single case report met the inclusion criteria. Diascopy was used on six algorithms (66.67%) and X-ray was included once (11.11%; 44.44% with text mentions); these were considered helpful tools in the diagnosis of intravascular and exogenous pigmentations, respectively. Surface rubbing was described once in the text (11.11%). CONCLUSIONS: Diascopy was the most applied method followed by X-ray and surface rubbing. The limited scope of these procedures only makes them useful when a positive result is obtained, turning biopsy into the most recommended technique when diagnosis cannot be established on clinical grounds alone. Key words:Algorithm, differential diagnosis, flow chart, oral mucosa, oral pigmentation, systematic review.