Surface changes on comet 67P/Churyumov-Gerasimenko suggest a more active past.

The Rosetta spacecraft spent ~2 years orbiting comet 67P/Churyumov-Gerasimenko, most of it at distances that allowed surface characterization and monitoring at submeter scales. From December 2014 to June 2016, numerous localized changes were observed, which we attribute to cometary-specific weathering, erosion, and transient events driven by exposure to sunlight and other processes. While the localized changes suggest compositional or physical heterogeneity, their scale has not resulted in substantial alterations to the comet's landscape. This suggests that most of the major landforms were created early in the comet's current orbital configuration. They may even date from earlier if the comet had a larger volatile inventory, particularly of CO or CO2 ices, or contained amorphous ice, which could have triggered activity at greater distances from the Sun.

Rosetta's comet 67P/Churyumov-Gerasimenko sheds its dusty mantle to reveal its icy nature.

The Rosetta spacecraft has investigated comet 67P/Churyumov-Gerasimenko from large heliocentric distances to its perihelion passage and beyond. We trace the seasonal and diurnal evolution of the colors of the 67P nucleus, finding changes driven by sublimation and recondensation of water ice. The whole nucleus became relatively bluer near perihelion, as increasing activity removed the surface dust, implying that water ice is widespread underneath the surface. We identified large (1500 square meters) ice-rich patches appearing and then vanishing in about 10 days, indicating small-scale heterogeneities on the nucleus. Thin frosts sublimating in a few minutes are observed close to receding shadows, and rapid variations in color are seen on extended areas close to the terminator. These cyclic processes are widespread and lead to continuously, slightly varying surface properties.

A homogeneous nucleus for comet 67P/Churyumov-Gerasimenko from its gravity field.

Cometary nuclei consist mostly of dust and water ice. Previous observations have found nuclei to be low-density and highly porous bodies, but have only moderately constrained the range of allowed densities because of the measurement uncertainties. Here we report the precise mass, bulk density, porosity and internal structure of the nucleus of comet 67P/Churyumov-Gerasimenko on the basis of its gravity field. The mass and gravity field are derived from measured spacecraft velocity perturbations at fly-by distances between 10 and 100 kilometres. The gravitational point mass is GM = 666.2 ± 0.2 cubic metres per second squared, giving a mass M = (9,982 ± 3) × 10(9) kilograms. Together with the current estimate of the volume of the nucleus, the average bulk density of the nucleus is 533 ± 6 kilograms per cubic metre. The nucleus appears to be a low-density, highly porous (72-74 per cent) dusty body, similar to that of comet 9P/Tempel 1. The most likely composition mix has approximately four times more dust than ice by mass and two times more dust than ice by volume. We conclude that the interior of the nucleus is homogeneous and constant in density on a global scale without large voids. The high porosity seems to be an inherent property of the nucleus material.

COMETARY SCIENCE. 67P/Churyumov-Gerasimenko surface properties as derived from CIVA panoramic images.

The structure and composition of cometary constituents, down to their microscopic scale, are critical witnesses of the processes and ingredients that drove the formation and evolution of planetary bodies toward their present diversity. On board Rosetta's lander Philae, the Comet Infrared and Visible Analyser (CIVA) experiment took a series of images to characterize the surface materials surrounding the lander on comet 67P/Churyumov-Gerasimenko. Images were collected twice: just after touchdown, and after Philae finally came to rest, where it acquired a full panorama. These images reveal a fractured surface with complex structure and a variety of grain scales and albedos, possibly constituting pristine cometary material.

Automatic dosage of hydrogen peroxide in solar photo-Fenton plants: development of a control strategy for efficiency enhancement.

The solar photo-Fenton process is widely used for the elimination of pollutants in aqueous effluent and, as such, is amply cited in the literature. In this process, hydrogen peroxide represents the highest operational cost. Up until now, manual dosing of H(2)O(2) has led to low process performance. Consequently, there is a need to automate the hydrogen peroxide dosage for use in industrial applications. As it has been demonstrated that a relationship exists between dissolved oxygen (DO) concentration and hydrogen peroxide consumption, DO can be used as a variable in optimising the hydrogen peroxide dosage. For this purpose, a model was experimentally obtained linking the dynamic behaviour of DO to hydrogen peroxide consumption. Following this, a control system was developed based on this model. This control system - a proportional and integral controller (PI) with an anti-windup mechanism - has been tested experimentally. The assays were carried out in a pilot plant under sunlight conditions and with paracetamol used as the model pollutant. In comparison with non-assisted addition methods (a sole initial or continuous addition), a decrease of 50% in hydrogen peroxide consumption was achieved when the automatic controller was used, driving an economic saving and an improvement in process efficiency.

Images of asteroid 21 Lutetia: a remnant planetesimal from the early Solar System.

Images obtained by the Optical, Spectroscopic, and Infrared Remote Imaging System (OSIRIS) cameras onboard the Rosetta spacecraft reveal that asteroid 21 Lutetia has a complex geology and one of the highest asteroid densities measured so far, 3.4 ± 0.3 grams per cubic centimeter. The north pole region is covered by a thick layer of regolith, which is seen to flow in major landslides associated with albedo variation. Its geologically complex surface, ancient surface age, and high density suggest that Lutetia is most likely a primordial planetesimal. This contrasts with smaller asteroids visited by previous spacecraft, which are probably shattered bodies, fragments of larger parents, or reaccumulated rubble piles.

Economic evaluation of the photo-Fenton process. Mineralization level and reaction time: the keys for increasing plant efficiency.

The use of the solar photo-Fenton process is proposed to degrade Paracetamol in water in order to form biodegradable reaction intermediates which can be finally removed with a downstream biological treatment. Firstly, biodegradability enhancement with photo-Fenton treatment time has been evaluated; the minimum mineralization level should be at least 18.6% where Paracetamol has been degraded and biodegradability efficiency is higher than 40%. 20 mg L(-1) of Fe(2+) and 200 mg L(-1) of H(2)O(2) were selected in a lab-scale study looking at Paracetamol's degradation rate and organic carbon mineralization rate. As a result of scaling up the process at a pilot plant, 157.5 mg L(-1) of Paracetamol (∼1 mM) was treated in 25 min of photo-Fenton treatment achieving the desired biodegradability. A further economic evaluation shows how the proposed treatment strategy markedly increases plant efficiency, resulting in an 83.33% reduction in reagent cost and a 79.11% reduction in costs associated with reaction time. Total cost is reduced from 3.4502 €/m(3) to 0.7392 €/m(3).

A transiting giant planet with a temperature between 250 K and 430 K.

Of the over 400 known exoplanets, there are about 70 planets that transit their central star, a situation that permits the derivation of their basic parameters and facilitates investigations of their atmospheres. Some short-period planets, including the first terrestrial exoplanet (CoRoT-7b), have been discovered using a space mission designed to find smaller and more distant planets than can be seen from the ground. Here we report transit observations of CoRoT-9b, which orbits with a period of 95.274 days on a low eccentricity of 0.11 +/- 0.04 around a solar-like star. Its periastron distance of 0.36 astronomical units is by far the largest of all transiting planets, yielding a 'temperate' photospheric temperature estimated to be between 250 and 430 K. Unlike previously known transiting planets, the present size of CoRoT-9b should not have been affected by tidal heat dissipation processes. Indeed, the planet is found to be well described by standard evolution models with an inferred interior composition consistent with that of Jupiter and Saturn.

E-type asteroid (2867) Steins as imaged by OSIRIS on board Rosetta.

The European Space Agency's Rosetta mission encountered the main-belt asteroid (2867) Steins while on its way to rendezvous with comet 67P/Churyumov-Gerasimenko. Images taken with the OSIRIS (optical, spectroscopic, and infrared remote( )imaging system) cameras on board Rosetta show that Steins is an oblate body with an effective spherical diameter of 5.3 kilometers. Its surface does not show color variations. The morphology of Steins is dominated by linear faults and a large 2.1-kilometer-diameter crater near its south pole. Crater counts reveal a distinct lack of small craters. Steins is not solid rock but a rubble pile and has a conical appearance that is probably the result of reshaping due to Yarkovsky-O'Keefe-Radzievskii-Paddack (YORP) spin-up. The OSIRIS images constitute direct evidence for the YORP effect on a main-belt asteroid.

UNE-EN ISO 9001-2000 en el sistema sanitario público / No disponible

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UNE-EN ISO 9001-2000 en el sistema sanitario público / No disponible

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Buccodental pathology in patients with insulin-dependent diabetes mellitus: a clinical study.

OBJECTIVE: A study is made to determine whether patients with type 1 (insulin-dependent) diabetes mellitus (IDDM) suffer oral complications attributable to the disease, or whether some disorder of the oral cavity can be regarded as pathognomonic of diabetes. MATERIAL AND METHODS: Thirty juvenile diabetics and 30 healthy individuals were evaluated for dental caries and oral mucosal lesions, with the performance of basal and stimulated sialometry in all cases, to assess possible alterations in salivary flow. In addition, an study of periodontal variables was made such as the presence of bacterial plaque, gingival status and attachment losses. RESULTS AND CONCLUSIONS: The diabetics were found to have significantly greater periodontal attachment loss, even though oral hygiene was significantly better among these patients. There were no differences between the two groups in terms of the number of caries, the presence of mucosal lesions or salivary flow.

Estudio clínico sobre la patología bucodentaria en el paciente diabético tipo 1 / Buccodental pathology in patients with insulin-dependent diabetes mellitus: a clinical study

Objetivo: Comprobar si los pacientes diabéticos insulino-dependientes presentaban complicaciones a nivel bucal debidas a su enfermedad o si existía alguna patología patognomónica de la diabetes mellitus en la cavidad oral. Material y métodos: Se realizó una exploración de 30 individuos diabéticos juveniles (DM 1) y 30 individuos sanos en el que se consignó la existencia de caries dental y la posible existencia de lesiones en la mucosa oral, se realizó una sialometría basal y estimulada en la totalidad de los pacientes para estudiar posibles alteraciones en el flujo salival, y se realizó un estudio de variablesperiodontales tales como la presencia de placa bacteriana, estudio de las condiciones gingivales y de la pérdida de inserción. Resultados y conclusiones: Los diabéticos tenían una mayor pérdida de inserción en su periodonto, siendo esta diferencia significativa. Este hecho ocurría incluso cuando las condiciones de higiene oral eran significativamente mejores para el grupo diabético. No había diferencias en el número de caries encontradas, en la presencia de lesiones en la mucosa o en la tasa de flujo salival (AU)

Dental management of the patient with ischemic heart disease: an update.

Ischemic heart disease is the most common cause of death in developed countries. The classical protocols for providing dental care in these patients with chest angina or myocardial infarction were based on the classification of the American Society of Anesthesiologists (ASA), postponing therapy for a minimum of 6 months after infarction in order to ensure safer dental treatment. However, advances in diagnostic techniques and medical and surgical treatments in patients with heart disease have led to the development of more precise risk assessment protocols, thus allowing earlier post-infarction dental treatments and oral surgery, with acceptable safety margins.

HST and VLT investigations of the fragments of comet C/1999 S4 (LINEAR).

At least 16 fragments were detected in images of comet C/1999 S4 (LINEAR) taken on 5 August 2000 with the Hubble Space Telescope (HST) and on 6 August with the Very Large Telescope (VLT). Photometric analysis of the fragments indicates that the largest ones have effective spherical diameters of about 100 meters, which implies that the total mass in the observed fragments was about 2 x 10(9) kilograms. The comet's dust tail, which was the most prominent optical feature in August, was produced during a major fragmentation event, whose activity peaked on UT 22.8 +/- 0.2 July 2000. The mass of small particles (diameters less than about 230 micrometers) in the tail was about 4 x 10(8) kilograms, which is comparable to the mass contained in a large fragment and to the total mass lost from water sublimation after 21 July 2000 (about 3 x 10(8) kilograms). HST spectroscopic observations during 5 and 6 July 2000 demonstrate that the nucleus contained little carbon monoxide ice (ratio of carbon monoxide to water is less than or equal to 0.4%), which suggests that this volatile species did not play a role in the fragmentation of C/1999 S4 (LINEAR).

Local and systemic induction of two defense-related subtilisin-like protease promoters in transgenic Arabidopsis plants. Luciferin induction of PR gene expression.

Following a pathogenic attack, plants are able to mount a defense response with the coordinated activation of a battery of defense-related genes. In this study we have characterized the mode of expression of the P69B and P69C genes from tomato (Lycopersicon esculentum Mill.), which encodes two closely related subtilisin-like proteases associated with the defense response. We have compared the mode of gene regulation in heterologous transgenic Arabidopsis plants harboring promoter-beta-glucuronidase (GUS) and promoter-luciferase (LUC) gene fusions for these two genes. These studies revealed that the P69B and P69C promoters are induced by salicylic acid as well as during the course of both a compatible and an incompatible interaction with Pseudomonas syringae. Furthermore, P69B and P69C expression takes place in both the local and the distal (noninoculated) leaves upon inoculation with bacteria but following different and unique tissue-specific patterns of expression that are also different to that described for most other classical PR genes. Also, we report that luciferin, the substrate for the reporter luciferase (LUC) gene, is able to activate expression of PR genes, and this may pose a problem when using this gene reporter system in studies related to plant defense.

Characterization of P69E and P69F, two differentially regulated genes encoding new members of the subtilisin-like proteinase family from tomato plants.

Subtilisin-like proteins represent an ancient family of serine proteases that are extremely widespread in living organisms. We report here the structure and genomic organization of two new transcriptionally active genes encoding proteins that belong to the P69 family of subtilisin-like proteases from tomato (Lycopersicon esculentum) plants. The two new members, P69E and P69F, are organized in a cluster and arranged in a tandem form. mRNA expression analysis and studies of transgenic Arabidopsis plants transformed with promoter-beta-glucuronidase fusions for each of these two genes revealed that they are differentially regulated, with each showing a highly specific mRNA expression pattern. P69E mRNA is expressed only in roots, while P69F mRNA is expressed only in hydathodes. A comparison of all the P69 amino acid sequences, gene structure, expression profiles, and clustered organization suggests a working model for P69 gene family evolution.

A genomic cluster containing four differentially regulated subtilisin-like processing protease genes is in tomato plants.

Screening of a genomic library from tomato plants (Lycopersicon esculentum) with a cDNA probe encoding a subtilisin-like protease (PR-P69) that is induced at the transcriptional level following pathogen attack (Tornero, P., Conejero, V., and Vera, P. (1996) Proc. Natl. Acad. Sci. U. S. A. 93, 6332-6337) resulted in the isolation of a cluster of genomic clones that comprise a tandem of four different subtilisin-like protease genes (P69A, P69B, P69C, and P69D). Sequence analyses and comparison of the encoded proteins revealed that all are closely related (79 to 88% identity), suggesting that all are derived from a common ancestral gene. mRNA expression analysis as well as studies of transgenic plants transformed with promoter-beta-glucuronidase fusions for each of these genes revealed that the four genes exhibit differential transcriptional regulation and expression patterns. P69A and P69D are expressed constitutively, but with different expression profiles during development, whereas the P69B and P69C genes show expression following infection with Pseudomonas syringae and are also up-regulated by salicylic acid. We propose that these four P69-like proteases, as members of a complex gene family of plant subtilisin-like proteases, may be involved in a number of specific proteolytic events that occur in the plant during development and/or pathogenesis.