Population increase has led to the growth of crowded, dense and congested cities, which has, in turn, resulted in the development at altitude and underground. Despite the benefits of crowded populations, such congestion has posed a threat to human quality of life. The concept of viability, in response to this concern, addresses the objective and subjective qualities that people expect from the environment. New Subsurface developments, which are mainly due to the increase in density and congestion in cities, has paid less attention to human biodiversity below the ground but to the functional aspects. Reduction of social oversight, security, ventilation, lighting and humidity control, readability, and orientation are among the most important challenges of this type of development. The need to create and popularize the use of dynamic and community-oriented public Spaces in the Subsurface has been the impetus for this research. In order to provide a model for improving livability in subterranean public Spaces of cities, the collected qualitative data were analyzed simultaneously by a documentary method (basic analysis) and grounded theory approach (complementary analysis). The data were collected employing a documentary approach and semi-structured interview. The Nvivo software was used for qualitative data analysis and coding. From the combination of baseline and complementary analyses, such elements as performance-accessibility, perceptual, identity, environment, and resilience components were identified and studied which are the key components that make up a livable Subsurface. Also, the grounded theory was used to present the model. Based on the questions raised in the interview process, 989 referrals were made. Following multiple revisions and integration of codes based on similarity during several stages of data summarization, 02 initial codes and 7 axial codes were extracted and after discovering the causal relationships, a livable Subsurface Space model based on the snowflake pattern was presented.

It is henceforth a commonplace; the science-fiction would be a refractory genre by nature against the definitive assimilation to the literary mainstream. We can say that the usual thematic of the genre, to which is added the irresistible propensity to prospect the future in all its forms, immunizes the SF against the “academic confinement” to the benefit of other forms of confinement. Indeed, the SF belongs to the great family of the paraliterature where the more or less listed subgenres are waiting to receive a likely definition. Popular genre which relies on a remarkable poetic, the SF is an open place to the imagination, to the verbal and the figurative creativity. It owns itself its subgenres, among other things, the Space opera which was, in a way, the original matrix of the speculative fiction and of its contemporary imitators. The Sternberg’s work did not have a special vocation to feed the already rich world of the science-fiction. It constitutes however a new step liable to bring a touch of self-reflexivity, we will notice that, to the history of this genre. French: “Le Navigateur” de Jacques Sternberg ou la phylogenese parodiee du Space opera C’est dorenavant un lieu commun, la science-fiction serait un genre par nature refractaire a l’assimilation definitive au mainstream litteraire. Nous dirons que les thematiques habituelles du genre, auxquelles viennent se meler l’irresistible propension a prospecter l’avenir sous toutes ses formes, immunisent la SF contre “l’enfermement academique” au profit d’un enfermement d’un autre genre. En effet, celle-ci appartient, comme on le sait, a la grande famille de la paralitterature ou se cotoient les sous-genres plus ou moins repertories en attente de recevoir un semblant de definition. Genre populaire s’appuyant sur une poetique singuliere, la SF est un lieu ouvert a l’imagination, a la creativite verbale et figurative. Elle possede elle-meme ses sous-genres, entre autres, le Space opera qui fut en quelque sorte la matrice originelle de la fiction speculative et de ses emules contemporaines. L’oeuvre sternbergienne n’eut guere pour vocation de nourrir le repertoire deja riche de la science-fiction. Elle constitue neanmoins une etape non repertoriee susceptible d’apporter, nous le constaterons, une touche d’auto-reflexivite a l’histoire du genre.Keywords: Jacques Sternberg, Nouvelle, Science-Fiction, Space Opera, Aventure, Fiction Speculative

Background: Cement Space is necessary for seatabillity and fitness of cast crowns, but can affect crown's retention. In this study the interrelationship between them was investigated via die spacing.Materials and Method: For evaluating the effect of die spacing (cement Space) on crown retention after cementation, 50 similar machined metallic dies were prepared and divided into five groups and coated with 0.2, 4, 6, 8 layers of paint-on standard die Spacer, respectively. Cast crowns. Were fabricated on the dies using base metal alloys, and then cemented with zinc phosphate cement under a constant load of 5kg for 10 minutes. The samples were started in distilled water for 48 hours. Then the force required to remove each crown from the die was measured with instron.Results: Statistical analysis revealed a significant increase in the force required (crown retention) by adding layers of die Spacer (p<0.05).Conclusion: Because retention didn't show any significant increase with more than 4 layers of die Spacer, so optimum thickness of die Spacer (or cement Space produced) is suggested to be 4 layers equal to 40 microns.

Purpose: The aim of this study was to compare the effects of A) a flame heated endo plugger, B) GatesGlidden drills and C) GPX drills on the apical seal for the purpose of post Space preparation. Materials & Methods: The crowns of sixty six extracted maxillary central teeth were removed from CEJ by a diamond disc and the root canals were prepared and obturated with guttapercha and sealer (Ah26) using lateral condensation technique. Six teeth were used as positve and negative control groups and the other sixty teeth were divided into 3 groups, each group containing 20 teeth. The post Space in these 3 groups was made by either A/a hot plugger, B/# 3or# 4 Gates glidden drills and C/# 40 or # 50 GPX drills and apical dye leakage in each group was measured by stereomicroscope and the Anova test was used to compare the mean amount of dye leakage between groups.Results: Between these 3 groups, the minimal mean dye leakage was related to the hot plugger group and the maximum mean leakage was observed in Gates glidden drill group. There was significant statistical difference between the groups (P=0.005).Conclusion: The GPX drills for the purpose of post Space preparation affect apical seal less than Gates glidden drills.

To ensure optimal operation of the drip irrigation system, it should be evaluated periodically. This research was conducted to evaluate the technical and hydraulic performance of Subsurface drip irrigation system in sugar cane plantation in Sugar Cane Research and Training Institute of Khuzestan during growing seasons of 2016-2017 and 2017-2018. For this study, four laterals were selected in experimental field (the first, one third, two third and the last laterals) and four sections including the first, one third, two thirds, and the last were determined on each laterals. Then, the volume of effluent water was measured for three minutes at any measurement point and the system parameters were calculated. Results of the evaluation of the drippers in the laboratory showed that the manufacture's coefficient variations (Cv), coefficient of uniformity (Cu), and distribution uniformity (Eu), coefficients were 15%, 90%, and 84 percent and the values of the exponent x and the k coefficient in the discharge-pressure equation were, respectively,-0. 043 and 2. 41. Means of Cu, Eu, coefficient of flow variations (Vqs), and Uqs during two growing seasons were 89. 2%, 87. 8%, 10. 3%, and 89. 7 percent, respectively. Based on these results, system performance was generally good. Also, by measuring pressure at different points of the system in the middle of the second growing season, the ASAE assessment indicators including: Vqs, Uqs, Vhs, and Vpf were 9%, 91%, 25%, and 13 percent, respectively. Thus, in terms of the overall performance of the drippers and uniformity of distribution the studied irrigation system was considered to be relatively good to good.

The sources of groundwater pollution such as, industrial effluents, sewage and extensive farming have lead to agrochemical pollution. Mathematical modeling helps to analyze the existing situation, allows forecasting, and to evaluate the effects of changes in the surrounding water quality. The present research has been focused mainly towards understanding the various processes affecting the transport of chemicals in soils. Dispersion coefficient for the sandy loam soil was found to be 0.247 m2/d, 0.150 m2/d and 0.01 m2/d for nitrates, phosphates and Chlorpyriphos through column, and 0.337 m2/d, 0.217 m2/d and 0.077 m2/d for nitrates, phosphates and Chlorpyriphos through channel studies, respectively. For similar analysis of the breakthrough curves, dispersion coefficient for the clay soil was found to be 0.0835 m2/d, 0.0632 m2/d and 0.008 m2/d for nitrates, phosphates and Chlorpyriphos through column and 0.147 m2/d , 0.0848m2/d and 0.022 m2/d for nitrates, phosphates and Chlorpyriphos through channel studies, respectively. The one-dimensional analytical model has been used and validated with the experimental data obtained from column and channel studies in sandy loam and clay soils and compared with model output (in which total elimination rate “K” is considered as zero). From this a variation of about 40-60 percent in the leaching characteristics of pollutants was being observed (nitrates, phosphates and chlorpyriphos).