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Open access

Zahra Barati and Mojgan Afkhami

Abstract

In this paper, we study the planar and outerplanar indices of some graphs associated to a commutative ring. We give a full characterization of these graphs with respect to their planar and outerplanar indices when R is a finite ring.

Open access

Elena Benito, Eufemia Varela and María Rodríguez-Alleres

Abstract

The primary purpose of this work was to assess the persistence of water repellency in the surface horizon of coarse-textured soils under natural Quercus robur ecosystems, and Pinus pinaster and Eucalyptus globulus plantations, in the northwest of the Iberian Peninsula. Water repellency was determined by applying the water drop penetration test (WDPT) to soil samples collected from variable depths (0–40 cm). Measurements were made on field-moist samples obtained at the end of the dry period and on samples dried at 25ºC in the air. All soils exhibited very high (severe to extreme) water repellency in the topmost soil layer (0–5 cm) but no significant differences among the three plant species studied. Extreme persistence was observed down to 20 cm in the soils under eucalyptus and down to 10 cm in those under pine. The soils under oak were those exhibiting the highest variability in water repellency and the greatest decrease in it with increasing depth (especially in relation to soils under eucalyptus).

Water repellency exhibited significant positive correlation with the C content and C/N ratio of the soils. Soil water repellency was similar in the air-dried samples and field-moist samples.

Open access

Libor Ansorge and Adam Beran

Abstract

Evaporation and evapotranspiration is crucial part of hydrological and water resource management studies e.g. water footprinting. Proper methods for estimating evaporation/potential evapotranspiration using limited climatic data are critical if the availability of climatic data is extremely limited. In a large scale studies are very often used generalized (modelled or gridded) input data. For a large scale water footprint studies is also important to find methods as simple as possible with quantifiable error. In our study, nine simple temperature-based empirical equations were compared with a long term time series of real evaporation data from a 20 m2 tank at Hlasivo station. In the first step, we used real temperature measured at Hlasivo station for validation of equations. In the second step, the gridded temperature data (interpolated datasets) derived from the meteorological stations were used. For both datasets, the differences between observed and predicted values were categorized into three groups of accuracy and the statistical indices of each equation were calculated. Very good results were achieved with the Hamon equation from 1961 and the Oudin equation for both datasets with index of agreement (d) higher than 0.9, cross-correlation coefficient (R 2) around 0.7 and root mean square error (RMSE) around 0.5 mm∙(24 h)−1 The Kharrufa equation, which was developed for semi-arid or arid areas, also provides results with sufficient accuracy. Comparison of the results with similar studies showed a lower accuracy of very simple equations against more complex equations, which have RMSE lower than 0.25 mm∙(24 h)−1. But for some kind of studies, quantifiable errors with sufficient accuracy can be more important than the absolute accuracy.

Open access

Ala Istratenco

Abstract

Chronic rhinosinusitis with nasal polyps (CRSwNP) is considered a multifactorial pathology with negative impact on the quality of life and considerable socio-economic effects. The pathogenesis of CRSwNP has not yet been fully elucidated despite remarkable studies in this field. This limits the pathogenic treatment and, therefore, the pathological process is expressed by a greater tendency of recurrence. Patients with recurrent CRSwNP remain in a severe state and therapeutically uncontrolled. In recent studies, the involvement of oxidative stress (OS) in the pathogenesis of CRSwNP has been more frequently mentioned. CRSwNP is considered a response of the sinonasal tissue on the inflammatory state, associated with OS and production of reactive oxygen species, causing injury to sinonasal tissues. It was demonstrated that the amount of ROS in the nasal polyp tissue corresponds to the severity of CRSwNP.

A literature review on the role of OS in the pathogenesis of CRSwNP was undertaken. The relevant information was identified using a search of electronic databases. Keywords used to highlight relevant papers were a combination of “chronic rhinosinusitis with nasal polyps” and “oxidative stress”.

This review demonstrates that there is a strong relationship between OS and CRSwNP pathogenesis. It is hypothesized that antioxidants may have a preventive role in CRSwNP. Nevertheless, additional research is required to further evaluate the effectiveness of antioxidant therapy.

Open access

T.S. Blyth and M.H. Almeida Santos

Abstract

We investigate the class BA of ordered regular semigroups in which each element has a biggest associate x = max {y | xyx = x}. This class properly contains the class PO of principally ordered regular semigroups (in which there exists x = max {y | xyx x}) and is properly contained in the class BI of ordered regular semigroups in which each element has a biggest inverse x◦. We show that several basic properties of the unary operation x x in PO extend to corresponding properties of the unary operation x x in BA. We consider naturally ordered semigroups in BA and prove that those that are orthodox contain a biggest idempotent. We determine the structure of some such semigroups in terms of a principal left ideal and a principal right ideal. We also characterise the completely simple members of BA. Finally, we consider the naturally ordered semigroups in BA that do not have a biggest idempotent.

Open access

Vlad Budu, Tatiana Decuseara, Ioan Alexandru Bulescu, Lavinia Ilinca and Alexandru Panfiloiu

Abstract

Inverted papilloma is a rare benign sinonasal tumor with a still unclear etiology. In the last decades, HPV implication in inverted papilloma etiopathogeny has been studied and demonstrated in some scientific research papers, but with no causality proven. Imagistic investigations and the Krouse classification establish the surgical approach. Endoscopic surgery represents the golden standard treatment for most cases of inverted papilloma, while external or combined approaches present limited indications.

The authors present a case and therapeutic plan of an inverted papilloma located in the ethmoid sinus, with origin in the lamina papyracea and high-risk HPV implication.

Open access

R. K. Schuster

Summary

During a survey on tapeworm larval stages in Artemia franciscana from an artificial pond in Dubai, United Arab Emirates, a high prevalence of Eurycestus avoceti-like cysticercoids was established. Adult male and female crustaceans showed a prevalence of 61.9 and 62.7 %, respectively. The intensity ranged from one to four and one to three cyst, respectively. Out of 215 examined cysticercoids, 207 specimens had morphological features matching with E. avoceti. The flaky structure of the surrounding capsule, the elongated shape of the cysticercoid and the larger number of hooklets on the suckers suggest that the eight further larval cestodes belonged to another species of the genus Eurycestus.

Open access

Duilio Iamonico and Ridha El Mokni

Abstract

Populations of Atriplex canescens var. gigantea were found in Lamta, Bouficha-Enfidha (central Tunisia), and Medenine (southern Tunisia). Literature data concerning the presence of this species in Tunisia are contradictory but now our data confirm its occurrence in the country. On the other hand, this variety is reported in the present paper for the first time both in Tunisia and in North Africa in general. Morphological characters and ecological data are presented, as well as notes about patterns of infraspecific variability of A. canescens. Nomenclatural notes on infraspecific names in A. canescens, as well as on the closely related species A. garrettii, are provided. The types of the names A. canescens var. laciniata, A. canescens var. macilenta, A. garrettii, Obione occidentalis var. angustifolia, and Pterochiton occidentale, that in earlier publications were erroneously considered to be holotypes, are in fact lectotypes (for most of taxa) under Art. 9.10 of the ICN. Isolectotypes were found at CAS (A. canescens var. laciniata and A. canescens var. macilenta), GH (A. canescens var. macilenta), and YU (Atriplex nuttallii).

Open access

Shanshan He, Yi Qian, Wenliang Xue and Longdi Cheng

Abstract

To improve airflow injection capacity of the main nozzle and decrease backflow phenomenon, a new main nozzle structure with two throats is designed. Negative pressure value and negative pressure zone length are first proposed evaluating the strength of backflow phenomenon. Commercial computational fluid dynamic (CFD) code “Fluent” is performed to simulate the flow field inside and outside the main nozzle. Exit velocity increases about 10 m/s in new main nozzle. Airflow core length of the new main nozzle is 35% higher than that of commonly used main nozzle. Smaller negative pressure value and shorter negative pressure zone length mean a weaker backflow phenomenon in the new main nozzle. Bigger air drag force indicates stronger weft insertion ability in the new main nozzle.

Open access

Marcin Nabrdalik and Michał Sobociński

Abstract

The paper presents analysis of stress distribution in the friction node of knee joint endoprosthesis where sleds are made of various titanium alloys and CoCrMo cooperate with spherical polyethylene inserts. Currently used titanium alloys consists of Nb, Ta, Zr or Mo and with lesser value of Young’s modulus than Ti6Al4V alloy, or steel CoCrMo, which significantly varies from other metal materials. The obtained results make it possible to indicate the “weak points” of the accepted solution, and thus counteract the subsequent effects resulting from premature wear of endoprosthesis elements. The analysis was conducted with numerical method of ADINA System 8.6. The Finite Elements Method allowed to compute and present stress distribution quickly in all elements of the model.