Spiral-CT-based assessment of tracheal stenoses using 3-D-skeletonization

PURPOSE: Demonstration of a technique for three-dimensional (3-D) assessment of tracheal-stenoses, regarding site, length and degree, based on spiral computed tomography (S-CT). PATIENTS AND METHODS: S-CT scanning and automated segmentation of the laryngo-tracheal tract (LTT) was followed by the extraction of the LTT medial axis using a skeletonization algorithm. Orthogonal to the medial axis the LTT 3-D cross-sectional profile was computed and presented as line charts, where degree and length was obtained. Values for both parameters were compared between 36 patients and 18 normal controls separately. Accuracy and precision was derived from 17 phantom studies. RESULTS: Average degree and length of tracheal stenoses was found to be 60.5% and 4.32 cm in patients compared with minor caliber changes of 8.8% and 2.31 cm in normal controls (p < 0.0001). For the phantoms an excellent correlation between the true and computed 3-D cross-sectional profile was found (p < 0.005) and an accuracy for length and degree measurements of 2.14 mm and 2.53% respectively could be determined. The corresponding figures for the precision were found to be 0.92 mm and 2.56%. CONCLUSION: LTT 3-D cross-sectional profiles permit objective, accurate and precise assessment of LTT caliber changes. Minor LTT caliber changes can be observed even in normals and, in case of an otherwise normal S-CT study, can be regarded as artifacts.     

Scientific output and impact of postdoctoral scientists: a gender perspective

This paper analyses the scientific output and impact of 731 Ph.D. holders who were awarded their doctorate at Spanish universities between 1990 and 2002. The aim was to identify any differences in the amount of scientific output and the impact of publications, in terms of citations, according to gender. The analysis revealed no significant differences in the amount of scientific output between males and females. However, the proportion of female Ph.D. holders with no postdoctoral output was significantly higher than that of their male counterparts, and the median number of papers published after Ph.D. completion was also lower among women. As regards pre- and postdoctoral research, the data showed that early scientific output may be a good predictor of subsequent productivity in both gender groups. The results also indicated that articles by female Ph.D. holders were cited significantly more often, even when self-citations were excluded.     

Characterization of the Accelerometric Environment of DCMIX2/3 Experiments

A comparative analysis of the vibratory environment of the DCMIX2/3 thermodiffusion experiments is presented here by using acceleration signals coming from different sensors placed in the Destiny, Columbus and Kibo modules. The es03 sensor nearest to the experimental device and located inside the Glovebox (Destiny module) has been defined as reference. Data were downloaded from the NASA PIMS website paying special attention to the runs coinciding with disturbances such as dockings or extravehicular activities (EVAs) as they could particularly affect the International Space Station (ISS) microgravity levels. The analyses have been made minute by minute for the three acceleration components by using the Frequency Factor Index (FFI), Spectral Entropy (SEN) and Root Mean Square (RMS) values evaluated over one-third-octave frequency bands. Spearman’s rank correlation coefficient and the coherence function have been used to investigate the degree of linear correlation between the reference signal and the other ones. SEN evolution showed different patterns compared to the reference. Also, RMS values surpassing the ISS microgravity limits were detected in all sensors, mainly at low frequency bands (<?10 Hz) and prevailing on z_A direction. However the sensors located in the Destiny module better accomplished the ISS vibratory limits requirements. Finally, some degree of linear correlation at structural frequencies (<?3 Hz) has also been detected. Overall, the sensors placed in the Destiny, Columbus and Kibo modules presented different vibratory characteristics and, despite they offer valuable information of the whole environment, may not be sufficient to properly characterize DCMIX2/3 experiments.     

Effect of Natamycin on Physical Properties of Starch Edible Films and Their Effect on Saccharomyces cerevisiae Activity

The effectiveness of using a tapioca starch–glycerol matrix containing natamycin to control Saccharomyces cerevisiae activity in a model system was studied and the effect of the formulation on physico-chemical properties was also evaluated. The presence of natamycin tended to depress firmness at break and Young modulus and to increase strain at break. Colour was also affected by antimycotic presence. The importance of these changes will be determined by the characteristics of the product to which the antimicrobial film will be applied. The films developed were capable of acting as a hurdle against S. cerevisiae in food systems during storage: they acted as an effective reservoir of the antimycotic which was also available to prevent an external contamination. The films containing 1.85 mg?natamycin/dm² of natamycin developed a fungistatic effect till 72 h of storage, while those with a 3.70-mg natamycin/dm² concentration developed a fungicidal action allowing the selection of the proper formulation according to the antimicrobial goal pursuit. As natamycin addition affects mechanical properties and colour of the films, it is advisable to use the lower natamycin concentration that allows the attainment of the goal pursued for film application.     

The Conversion of Butadiene on Thiophene Hydrodesulfurization Catalysts

The production of thiophene via heterocyclization of butadiene with sulfur (hcycl.) has been studied in the interaction of butadiene with sulfided, alumina supported nickel (Ni6), molybdena?Calumina (Mo6) and nickel promoted molybdena?Calumina of a 0.35 atomic ratio of Ni:Mo (NiMo0.35). The sequence of the rates of thiophene production on these catalysts in a circulation system was the same (^hcyclm_NiMo0.35?>?^hcyclm_Mo6?>?^hcyclm_Ni6) than that for thiophene hydrodesulfurization observed before. The virtual activation energy values of the butadiene heterocyclization have been determined and compared with those of thiophene hydrodesulfurization determined before and with the strengths of bonds between reacting atoms and the different catalysts indicate calculated before. This comparison indicates that desorption of the product is the rate determining step in the butadiene heterocyclization.     

A bibliometric study of psychological research on tourism

The psychology of tourism is a new, multidisciplinary research field. However, no systematic analyses of the scientific production in this field have been carried out to date. This study presents a bibliometric analysis of the area of psychology of tourism between 1990 and 2005. The evolution of scientific production during this period, Price’s, Lotka’s and Bradford’s laws and citation patterns were studied. The results show a significant growth in the literature on the subject, as well as an increase in coauthorship and institutional collaboration. Bibliometric laws and empiric regularities observed in other disciplines are also present in this new research field.     

ISS Quasi-steady Accelerometric Data as a Tool for the Detection of External Disturbances During the Period 2009-2016

The present work aims to investigate the degree of correlation existing between the information contained in the ISS reduced quasi-steady accelerometric data and different external mechanical disturbances (reboostings, dockings/undockings, berthings/deberthings and Extra Vehicular Activities), compiled for the period 2009 to 2016. The eight hour mean (Mean_8h) and the eight hour root mean square (RMS_8h) acceleration values, considered as reduced data, have been extracted from the quasi-steady records provided by NASA Principal Investigator Microgravity Services website. The advantage of applying the present strategy is to drastically reduce the amount of information to be processed all along these eight years. The Mean_8h values have been used for the evaluation of trends as function of time while the RMS_8h ones were used to define the level (weak, medium and strong) of the different kind of external mechanical disturbances considered. These criteria has been applied for approximately four hundred selected disturbances, compiled in the Appendix. Results indicate that reboosting is always detected as a strong disturbance, while dockings/undockings, as weak ones, having lower, though detectable level, depending on the type of spacecraft considered. Extra Vehicular Activities are undetectable by the use of this reduced quasi-steady approach. The inverse problem, in other words, knowing the value of the RMS_8h one could try to predict the kind of disturbance responsible of it, is thus feasible except for berthing/deberthings and Extra Vehicular Activities.