62 research outputs found
Additional stresses on buildings induced by vibration effects
No full textAbstractConstruction activities, blasting and traffic are the main sources of ground vibrations that may have a detrimental effect on buildings.The main objective of this research is to study the relationship between additional stresses on building induced by vibrations, vibration nature and building dynamic characteristics.Five numerical models were subjected to base excitation to represent different vibration sources and wave forms. These waves were scaled to the same peak acceleration.Experimental dynamic tests were carried out using five physical models with different characteristics. These models were subjected to different types of vibration. The vibration characteristics were identified and the models top acceleration responses were measured. Moreover, the models maximum stresses were measured due to each vibration load.The relationships between stress increasing, fundamental period and base excitation type were plotted; also the relationship between pseudo acceleration response at the top of the building and the frequency ratio between the model fundamental frequency and the base excitation predominant frequency was also plotted. These relations were analyzed and concluded to tangible results
The Libyan Arabic version of the Juvenile Arthritis Multidimensional Assessment Report (JAMAR)
No full textThe Juvenile Arthritis Multidimensional Assessment Report (JAMAR) is a new parent/patient reported outcome measure that enables a thorough assessment of the disease status in children with juvenile idiopathic arthritis (JIA). We report the results of the cross-cultural adaptation and validation of the parent and patient versions of the JAMAR in the Libyan Arabic language. The reading comprehension of the questionnaire was tested in 10 JIA parents and patients. Each participating centre was asked to collect demographic, clinical data, and the JAMAR in 100 consecutive JIA patients or all consecutive patients seen in a 6-month period and to administer the JAMAR to 100 healthy children and their parents. The statistical validation phase explored descriptive statistics and the psychometric issues of the JAMAR: the 3 Likert assumptions, floor/ceiling effects, internal consistency, Cronbach’s alpha, interscale correlations, test–retest reliability, and construct validity (convergent and discriminant validity). A total of 100 JIA patients (22.0% systemic, 26.0% oligoarticular, 25.0% RF negative polyarthritis, and 27.0% other categories) and 100 healthy children, were enrolled in a paediatric rheumatology centre. The JAMAR components discriminated well healthy subjects from JIA patients. Notably, there is no significant difference between the healthy subjects and their affected peers in the school-related problems variable. All JAMAR components revealed satisfactory psychometric performances. In conclusion, the Libyan Arabic version of the JAMAR is a valid tool for the assessment of children with JIA and is suitable for use both in routine clinical practice and clinical research
Using dynamic analysis of site vibration to select the suitable vibration limit
No full textThis study was done to select the appropriate vibration standard to be the adopted vibration standard for a construction project that was located in adjacent to many buildings. These buildings may be affected by project activities induced vibrations.Three common international vibration standards were revised and based on the dynamic analysis results, site conditions, the nature of the existing buildings and the expected construction activities, and the most appropriate vibration limit criteria were selected and tested then validated. The selection process was based on experimental study carried out using physical models and real vibration data recorded on the construction site. The validation process was based on monitoring the vibration effects on existing buildings.Experimental program was carried out using three physical models with dynamic characteristics within the range of the common existing buildings. These models were subjected to free vibration modal testing to ensure their dynamic characteristics. Three numerical finite element models for the three physical ones were built and calibrated using the free vibration test results. The numerical models were subjected to time history dynamic analysis using the vibration waveforms that represent the most effective construction vibrations. These waveforms were recorded onsite during different activities of the pilot project which was implemented to test all the project activities.The validation process was carried out by applying monitoring program on two of the project neighboring buildings. These buildings were selected to represent the most likely to be affected buildings by the construction activities. The monitoring program includes vibration and strain measurements for the building vibration responses.The results of validation process showed that the effectiveness of the selected vibration standard in estimating the level of damage on buildings subjected to the construction induced vibration. Keywords: Vibration effects, Vibration limits, Construction vibration, Dynamic testin
Using dynamic analysis of site vibration to select the suitable vibration limit
No full textAbstractThis study was done to select the appropriate vibration standard to be the adopted vibration standard for a construction project that was located in adjacent to many buildings. These buildings may be affected by project activities induced vibrations.Three common international vibration standards were revised and based on the dynamic analysis results, site conditions, the nature of the existing buildings and the expected construction activities, and the most appropriate vibration limit criteria were selected and tested then validated. The selection process was based on experimental study carried out using physical models and real vibration data recorded on the construction site. The validation process was based on monitoring the vibration effects on existing buildings.Experimental program was carried out using three physical models with dynamic characteristics within the range of the common existing buildings. These models were subjected to free vibration modal testing to ensure their dynamic characteristics. Three numerical finite element models for the three physical ones were built and calibrated using the free vibration test results. The numerical models were subjected to time history dynamic analysis using the vibration waveforms that represent the most effective construction vibrations. These waveforms were recorded onsite during different activities of the pilot project which was implemented to test all the project activities.The validation process was carried out by applying monitoring program on two of the project neighboring buildings. These buildings were selected to represent the most likely to be affected buildings by the construction activities. The monitoring program includes vibration and strain measurements for the building vibration responses.The results of validation process showed that the effectiveness of the selected vibration standard in estimating the level of damage on buildings subjected to the construction induced vibration
Reactive Oxygen Species Mediate the Suppression of Arterial Smooth Muscle T-type Ca2+ Channels by Angiotensin II
No full textAbstractVascular T-type Ca2+ channels (CaV3.1 and CaV3.2) play a key role in arterial tone development. This study investigated whether this conductance is a regulatory target of angiotensin II (Ang II), a vasoactive peptide that circulates and which is locally produced within the arterial wall. Patch clamp electrophysiology performed on rat cerebral arterial smooth muscle cells reveals that Ang II (100 nM) inhibited T-type currents through AT1 receptor activation. Blocking protein kinase C failed to eliminate channel suppression, a finding consistent with unique signaling proteins enabling this response. In this regard, inhibiting NADPH oxidase (Nox) with apocynin or ML171 (Nox1 selective) abolished channel suppression highlighting a role for reactive oxygen species (ROS). In the presence of Ni2+ (50 µM), Ang II failed to modulate the residual T-type current, an observation consistent with this peptide targeting CaV3.2. Selective channel suppression by Ang II impaired the ability of CaV3.2 to alter spontaneous transient outward currents or vessel diameter. Proximity ligation assay confirmed Nox1 colocalization with CaV3.2. In closing, Ang II targets CaV3.2 channels via a signaling pathway involving Nox1 and the generation of ROS. This unique regulatory mechanism alters BKCa mediated feedback giving rise to a “constrictive” phenotype often observed with cerebrovascular disease.</jats:p
Assessment of soil mixing with cement kiln dust to reduce soil lateral pressure compared to other soil improvement methods
No full textAbstractThe soil lateral earth pressure acting on retaining or wing walls of hydraulic structures is considered the most influential load in structural design of these walls. The general properties of the soil foundation and backfill soil are the factors that control the cost of engineering design of retaining or wing walls of hydraulic structures. Some water structures may be subjected to various forms of damage for reasons related to soil problems. These structures may need rapid intervention to repair these defects which are considered one of the most expensive and most complex flaws in the reform.In order to improve the mechanical properties of the soil backfill, which are reflected on the cost of new buildings or address problems of existing soil structures, this research compares between different soil improvement techniques, which can be easily applied to these kinds of buildings and has a significant effect. Many field tests were carried out to compare the retaining wall resistance to backfill soil using medium sand soils as backfill material processed in four different methods. These methods are filling sand using common compaction specifications, using sand filled baskets (gabions), soil reinforcement with geogrid and soil mixing with cement kiln dust.The results of experiments showed that the soil mixing with cement dust is considered the best method among the other used methods, although it may not be the fastest when considering the construction process
CaV3.2 Channels and BKCa-Mediated Feedback in Vascular Smooth Muscle
No full textThe vascular T-type Ca2+ channel, CaV3.2, regulates arterial tone by triggering Ca2+ sparks and activating large conductance Ca2+-activated K+ (BKCa) channels. Despite being an integral element of an arterial feedback loop, little is known of its regulation and how key receptors and signaling pathways use this channel to influence tissue perfusion. This thesis will begin to fill key knowledge gaps, undertaking experiments that progress from individual smooth muscle cells to whole arteries, and which entail the use of patch clamp electrophysiology, Ca2+ imaging, pressure myography, immunohistochemistry, quantitative polymerase chain reaction (qPCR) and computational modeling. In initial work, perforated patch electrophysiology was used in concert with Ca2+ imaging to illustrate the coordinated interplay between CaV3.2 and two other Ca2+ permeable conductances in setting voltage-dependent Ca2+ spark production and BKCa channel activation. A second layer of experiments subsequently revealed that caveolae help couple CaV3.2 to Ca2+ sparks generation by placing this T-type Ca2+ channel in close proximity to its intracellular target, ryanodine receptors (RyR). Disruption of the structural arrangement impaired the ability of CaV3.2 to mediate BKCa-mediated feedback in intact resistance arteries. Final experiments revealed that CaV3.2 channels are targeted by common vasoactive stimuli through unique signaling pathways. Of note, was the ability of Angiotensin II to suppress CaV3.2 channel activity through the generation of reactive oxygen species (ROS) by NADPH oxidase (Nox). In summary, this thesis advances our knowledge of Ca2+ handling in vascular smooth muscle by providing new regulatory insight into CaV3.2, a T-type Ca2+ channel involved in optimizing arterial tone and tissue perfusion
Guidelines to estimate Earthquake Loads on Buildings in Slum Areas
No full textSlums and non-engineering buildings are scattered in Egyptian cities. Here comes the challenge facing the state, including the engineering bodies, to determine the danger level to the residents’ lives, and to develop solutions and priorities for facing risks including earthquakes. The large size of slums necessitates the development of a simplified way for classifying structures in terms of their seismic resistance. This research proposes a simplified method to estimate the earthquake loads to be used for estimating the ability of such buildings to withstand the main and seismic loads, allowing the determination of the initial degree of danger on its condition. The proposed guideline ignores the effect of participation of all columns in resisting earthquake loads, especially in the absence of lateral stiffness members, which is the general condition of slums and focuses on the external columns only that are the most exposed to the seismic load. Also, this method considers only the resulting seismic vertical reactions. The validity of the proposed method was tested experimentally and analytically, while its accuracy was verified through a field study by comparing the results of its application on two buildings in Sharkia, Egypt. Numerical models for these buildings were built to determine their resistance under seismic loads. The study concluded how to predict the risks affecting such buildings using a simple process. This could be used to establish controls to re-planning the buildings of existing slum cities to ensure the safety or at least reduce the risk of collapses against moderate earthquakes
Interleukin-10 (−1082G/A) gene promotor polymorphism in Egyptian non-Hodgkin lymphoma patients: relation to other prognostic factors
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