205 research outputs found
Influence of gravel and adjuvant on the compressive strength and water absorption of concrete.
Concrete is the most commonly used material in civil engineering, given its economic cost and ease of manufacture. Its strength depends on the characteristics of its constituents. A good mix makes it possible to build solid, durable and economical structures. The present work aims to characterize the gravel of the Eastern region (quarry of eastern Morocco) by granulometric analysis and water absorption. Then, the studied gravel is used to produce three types of concrete (B20, B25 and B30), which were assessed in terms of water absorption and compressive strength. The last step is to study the effect of an adjuvant, more specifically a water reducer, on mechanical characteristics of local concrete. B25 concrete was chosen for the last step since it is the most used type in the region. Results show that adding a water reducer adjuvant, in this case 'Chrysoplast', can improve the compressive strength of concrete if the percentage added is accurately determined
Quantification and Identification of Road Organic Matter in an Absorbing Storm Basin, RN 20 Olivet-Orléans, France.
The deterioration of the quality of superficial and subsurface waters by motorway organic pollution is a problem of great concern nowadays. The absorption of road runoff waters through sinkhole clay filled in a karstic area has been proposed as a way to the attenuation pollution. The groundwaters near of surface are very vulnerable at this pollution. The study of the storm basin of Belle-Croix (RN 20 Loiret) indicates a diminution of DOC levels through the first meter of infiltration in sinkhole, and then little change occurs down 5 meters. However only the > 10 KD (10 nm) organic fraction is retained. This fraction is weakly fluorescent and should correspond to black carbon (BC) matter associated to clays as it is suggested by Electron Microscopy in Transmission EMT observation. The < 10 KD fraction which are the more fluorescent account for up to 80 % of total DOC at 5 meter depth, at the contact with the limestone
Messinian salinity crisis impact on the groundwater quality in Kert aquifer NE Morocco: Hydrochemical and statistical approaches.
Groundwater's studies at middle Kert aquifer in northeast of Morocco are very important due to the semi-arid character and its geological history. The region is recognized by messinian salinity crisis already 5.6 Ma. Water chemistry is mainly dominated by dissolution of evaporate rocks (Halite and Gypsum) related to outcropping and basement limits developed in Messinian age. Freshwater with total dissolved solids 740 mg/l (average value) in Tafersite district is chemically distinct from saline water with total dissolved solids of 9803 mg/l in the south zone. In wadis, water is S04-Cl-Ca type; they are influenced by the surrounding highlands located at the south of the plain. The investigation reveals that weathering of evaporated rocks is the processes responsible for high Na+, Ca2+, Mg2+, Cl andSO42- concentrations. Also, hydro chemical data displays that freshwater observed in the northwest part reflect the influence of freshwaters coming from metamorphic massive of Temsamane. The factorial analysis reveal three sources of salinization, the principal one is described above, whilst the dissolution of carbonates and human influence represented by NO3- played only a secondary role
Identification of R gene genotypes in Japanese wheat cultivars
Dissertação de mestrado em Psicologia Clínica e da Saúde (Psicopatologia e Psicoterapias Dinâmicas), apresentada à Faculdade de Psicologia e de Ciências da Educação da Universidade de CoimbraA presente investigação visa explorar múltiplas variáveis (sociodemográficas, clínicas e satisfação com o suporte social) na relação com o bonding materno.
O nosso principal objetivo foi perceber quais as diferenças entre as mães adultas e as mães adolescentes relativamente à forma como se vinculam (bonding) ao seu bebé, para isso procedemos às entrevistas de 57 mães, em que 29 são mães adultas e 28 são mães adolescentes.
Consoante os nossos resultados, pudemos inferir que as mães adolescentes apresentam valores de bonding inferiores aos valores das mães adultas. Quando comparamos o bonding com o suporte social também verificamos que as mães adolescentes apresentam valores de perceção do suporte social inferiores aos valores das mães adultas. Deste modo, a relação mãe-bebé vai sendo fortalecida consoante aumenta a idade das mães e a perceção que as mesmas têm em relação ao suporte social.The present investigation pretends to explore multiple variables (sociodemographic, clinic, and satisfaction with social support) and its relation to maternal bonding.
Our main goal was to understand which are the differences between adult mothers and teenage mothers as how they are bond to their baby. We interviewed 57 mothers, in which 29 are adult mothers and 28 are adolescent mothers.
From our results, we infer that teenage mothers have lower values than adult mothers on bonding. When we compare bonding with social support we also found that teenage mothers have lower values of social support perception relatively to adult mothers. We also conclude that mother-baby relationship and social support perception will be strengthened as mothers grow older
Impacts and social implications of landuse-environment conflicts in a typical Mediterranean watershed
In coastal watersheds, services and landuse favour coastal tourism and urbanization, depriving rural upstream of infrastructure and attention. This unbalanced management leads to an intensification of socioeconomic changes that generate a structural heterogeneity of the landscape and a reduction in the livelihoods of the rural population. The incessant dissociation between the objectives of the stakeholders triggers landuse-environment-economy conflicts which threaten to mutate large-scale development programs. Here, we used multi-assessment techniques in a Mediterranean watershed from Morocco to evaluate the effects of landuse change on water, vegetation, and perception of the rural population towards environmental issues. We combined complementary vegetation indexes (NDVI and EVI) to study long-term landuse change and phenological statistical pixel-based trends. We assessed the exposure of rural households to the risk of groundwater pollution through a water analysis supplemented by the calculation of an Integrated Water Quality Index. Later, we contrasted the findings with the results of a social survey with a representative sample of 401 households from 7 villages. We found that rapid coastal linear urbanization has resulted in a 12-fold increase in construction over the past 35 years, to the detriment of natural spaces and the lack of equipment and means in rural areas upstream. We show that the worst water qualities are linked to the negative impact of anthropogenic activities on immediately accessible water points. We observe that rural households are aware of the existence and gravity of environmental issues but act confusedly because of their low education level which generates a weak capacity to understand cause and effect relationships. We anticipate the pressing need to improve the well-being and education of the population and synergistically correct management plans to target the watershed as a consolidated system. Broadly, stakeholders should restore lost territorial harmony and reallocate landuse according to a sustainable environment-socioeconomic vision
Time-dependent density functional theory beyond the adiabatic local density approximation
In the current density functional theory of linear and nonlinear
time-dependent phenomena, the treatment of exchange and correlation beyond the
level of the adiabatic local density approximation is shown to lead to the
appearance of viscoelastic stresses in the electron fluid. Complex and
frequency-dependent viscosity/elasticity coefficients are microscopically
derived and expressed in terms of properties of the homogeneous electron gas.
As a first consequence of this formalism, we provide an explicit formula for
the linewidths of collective excitations in electronic systems.Comment: RevTeX, 4 page
Evaluation de la vulnérabilité sismique des bâtiments en béton arméen utilisant l'analyse dynamique incrémentale (Seismic vulnerability assessment of reinforced concrete buildings using Incremental Dynamic Analysis IDA)
Incrementaldynamic analysisIDA is a nonlineardynamic analysisthat offersa hugeopportunity to evaluatethe seismicresponseof the structureand takes into accountthe effects ofthe energy, thedurationand the frequencycontained in seismic record and product theeffectof these parametersas an inter-story drift ratio and maximumdisplacementinastructure,unlikethePUSHOVERanalysiswhichis a staticanalysisthat provides only anoverview oflesserseismicresponseson the structure.The occurrence of damage with varying degrees is a random process;therefore, the only appropriate tool to predict the distribution of expected losses would be probabilistic.Therefore we propose to establish fragility curves based on the data of the incremental dynamic analysis to precisely define a sequential pattern ofdamage and establish a level of structural damage of different seismic intensities of Moroccan real estat
Limits of near transfer: content- and operation-specific effects of working memory training
Working memory (WM) training typically leads to large performance gains in the practiced tasks, but transfer of these gains to other contexts is elusive. One possible explanation for the inconsistent findings of past research is that transfer may only occur when cognitive strategies acquired during training can also be applied in the transfer tasks. Therefore, we systematically varied the content domains and WM operations assessed by training and transfer tasks and, thereby, the extent to which similar cognitive strategies could be applied. We randomly assigned 171 young adults to 1 of 8 experimental groups who trained 1 of 2 working memory operations (storage and processing or relational integration ) with materials from 1 of 4 content domains (verbal, numerical, figural-icon, or figural-pattern), to an active or to a passive control group. Before and after 12 sessions of adaptive training within 2-3 weeks, performance was assessed in all eight WM tasks. Bayesian generalized-mixed effects models revealed improved performance in the trained tasks compared to the active control group. However, these improvements did not generalize to tasks measuring the same WM operation with different materials. Moreover, the comparison of the training groups with an active and a passive control group showed considerable differences, thus highlighting the importance of distinguishing between active and passive control. Overall, the findings revealed no evidence for transfer between tasks assumed to afford the same strategies.
Therefore, the adoption of specific cognitive strategies alone is unlikely to be responsible for transfer of WM training gains between tasks
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