On the vulnerability of some families of graphs

The toughness of a noncomplete graph G is defined as τ (G) = min{|S|/ω(G − S)}, where the minimum is taken over all cutsets S of vertices of G and ω(G − S) denotes the number of components of the resultant graph G − S by deletion of S. In this paper, we investigate the toughness of the corona of two connected graphs and obtain the exact value for the corona of two graphs belonging to some families as paths, cycles, wheels or complete graphs. We also get an upper and a lower bounds for the toughness of the cartesian product of the complete graph $K_2$ with a predetermined graph G.Peer Reviewe

A mini outburst from the nightside of comet 67P/Churyumov-Gerasimenko observed by the OSIRIS camera on Rosetta

Context. On 12 March 2015 the OSIRIS WAC camera onboard the ESA Rosetta spacecraft orbiting comet 67P/Churyumov-Gerasimenko observed a small outburst originating from the Imhotep region at the foot of the big lobe of the comet. These measurements are unique since it was the first time that the initial phase of a transient outburst event could be directly observed. Aims. We investigate the evolution of the dust jet in order to derive clues about the outburst source mechanism and the ejected dust particles, in particular the dust mass, dust-to-gas ratio and the particle size distribution. Methods. Analysis of the images and of the observation geometry using comet shape models in combination with gasdynamic modeling of the transient dust jet were the main tools used in this study. Synthetic images were computed for comparison with the observations. Results. Analysis of the geometry revealed that the source region was not illuminated until 1.5 h after the event implying true nightside activity was observed. The outburst lasted for less than one hour and the average dust production rate during the initial four minutes was of the order of 1 kg/s. During this time the outburst dust production rate was approximately constant, no sign for an initial explosion could be detected. For dust grains between 0.01-1 mm a power law size distribution characterized by an index of about 2.6 provides the best fit to the observed radiance profiles. The dust-to-gas ratio of the outburst jet is in the range 0.6-1.8. © 2016 ESO.The support of the national funding agencies of Germany (DLR), France (CNES), Italy (ASI), Spain (MEC), Sweden (SNSB; Grant No. 74/10:2), and the ESA Technical Directorate is gratefully acknowledged. H. Rickman was also supported by Grant No. 2011/01/B/ST9/05442 of the Polish National Science Center.Peer Reviewe

The Inter-relationship of Coaching Profiles and Levels of Mental Toughness: Preliminary Results of A Pilot Study.

Mental toughness (MT) is a personal, state-like capacity that facilitates the initiation and continuation of goal-directed activities in several domains, including sports. Sport coaches are key agents in positions of authority. Coaching philosophy has been identified as one of the key parts in the development of environments that promote MT. The Coach Orientation Questionnaire (COQ) groups coaches in six profiles (Traditional, Technological, Innovative, Collaborative, Communicator, and Confrontational) mostly based on their professional training, personality, and experience. Coaches’ levels of MT and coaching COQ profiles have not been investigated together. PURPOSE: To explore the relationship between the COQ coaching profiles with MT. METHODS: The study followed a cross-sectional design. Data from 37 male and eight female coaches (n = 45), with an age of 35.1 ± 11.7 years, were collected. The COQ and the Mental Toughness Index (MTI) were administered. MTI consists of eight items. Each item represents one MT key dimension (i.e., generalized self-efficacy, buoyancy, success mindset, optimistic style, context knowledge, emotion regulation, attention regulation, overcoming adversity). All analyses were conducted in SPSS. RESULTS: Based on the COQ scores, coaches fell into the following categories: Confrontational (19%), Traditional (19%), Communicator (18%), Innovative (17%), Technological (16%), and Collaborator (11%). The correlation analysis showed significant relationships between MT scores and the Technological (They like to use technology to study the sport. Assistants need to be competent to assist in that. Players must be predisposed to collaborate.) (r =.377; p = .011), Collaborator (They prefer delegation of tasks, while maintaining a climate of trust with players and the assistants) (r = .420; p = .005), and Confrontational (They criticize the training process, which creates a tense atmosphere) coach profiles (r =.474; p = .002). CONCLUSION: Our findings offer preliminary evidence for the relationship between coaches’ COQ profiles and levels of MT and support the continuation of data collection. Larger-scale studies should explore this relationship further (e.g., different settings). Future studies should also investigate the etiology behind those inter-relationships (e.g., COQ profiles with each MT key dimension score) and their effect on environment development. Limitations may include cross-sectional design and convenience sample

Medical resource use in patients with psoriatic arthritis in a comprehensive rheumatological center in Colombia

Psoriatic arthritis (PsA), a chronic systemic inflammatory disorder, impairs the quality of life of patients. The aim of this study was to describe the medical resource use in patients with PsA in a comprehensive rheumatological center in Colombia. We retrospectively analyzed patients diagnosed with PsA who were attended in a center of excellence for rheumatic diseases located in Bogotá, D.C. Colombia, from January to December 2019. A database of medical records was analyzed to identify the use of medical resources classified by specialized physician visits, medications and ambulatory services (e.g., diagnostic, laboratory or image procedures, physical therapy). We reported absolute and relative frequencies among diagnostic groups. This study had no risk for patients. Ninety-six patients with PsA were studied, 57% were women. The mean age was 58.08 (±12.3 years), 90.63% of diagnostic was arthropathic psoriasis, other diagnostics were rheumatoid arthritis without rheumatoid factor, unspecified site (2.08%) and psoriasis, unspecified (2.08%) (ICD-10 code L405, M060, L409, respectively). In terms of treatments, most of the patients used a conventional disease-modifying antirheumatic drugs (DMARDs), methotrexate was the most frequent (represented the 14% of prescription and 78% of patients). On the other hand, 56.25% of patients receive treatment with biological DMARDs (10% of prescription). Among these biologicals, adalimumab (17.71%) and secukinumab (16.67%) were the most used. Regarding other health services, the visit to the specialist and the RX were the most common (83.33% of patients). Chest RX and column RX (17.71% each) had the highest frequency. This is one of the first approaches to the estimation of use of medical resources of PsA in Colombia. Frequency of DMARS use was associated to the severity and medical control of patients

Regional surface morphology of comet 67P/Churyumov-Gerasimenko from Rosetta/OSIRIS images: The southern hemisphere

Aims. The OSIRIS camera on board the Rosetta spacecraft has been acquiring images of the comet 67P/Churyumov-Gerasimenko (67P)'s nucleus since August 2014. Starting in May 2015, the southern hemisphere gradually became illuminated and was imaged for the first time. Here we present the regional morphology of the southern hemisphere, which serves as a companion to an earlier paper that presented the regional morphology of the northern hemisphere. Methods. We used OSIRIS images that were acquired at orbits ~45-125 km from the center of the comet (corresponding to spatial resolutions of ~0.8 to 2.3 m/pixel) coupled with the use of digital terrain models to define the different regions on the surface, and identify structural boundaries accurately. Results. Seven regions have been defined in the southern hemisphere bringing the total number of defined regions on the surface of the nucleus to 26. These classifications are mainly based on morphological and/or topographic boundaries. The southern hemisphere shows a remarkable dichotomy with its northern counterpart mainly because of the absence of wide-scale smooth terrains, dust coatings and large unambiguous depressions. As a result, the southern hemisphere closely resembles previously identified consolidated regions. An assessment of the overall morphology of comet 67P suggests that the comet's two lobes show surface heterogeneities manifested in different physical/mechanical characteristics, possibly extending to local (i.e., within a single region) scales.© 2016 ESO.The support of the national funding agencies of Germany (DLR), France (CNES), Italy (ASI), Spain (MEC), Sweden (SNSB), and the ESA Technical Directorate is gratefully acknowledged.Peer Reviewe