31 research outputs found
Assessment of abnormally low tenders: a multinomial logistic regression approach
This study was performed in order to reveal factors affecting abnormally low tenders (ALTs) and to minimize negative effects of them. A thorough literature review was carried out to observe past research about the reasons of and possible solutions to ALTs. A questionnaire was prepared and submitted to construction professionals to capture negative impacts of ALTs based on the interviews with experts and past literature. 430 companies responded to the questionnaire. The data analysis was carried out by the multinomial logistic regression statistical tool. Having quality control systems and restricted procedure with prequalification procurement systems were main significant factors to reduce ALTs. Based on all significant factors, recommendations were made to construction professionals and companies to reduce adverse effects of ALTs.
First published online:Â 18 Sep 201
A Role for the Retinoblastoma Protein As a Regulator of Mouse Osteoblast Cell Adhesion: Implications for Osteogenesis and Osteosarcoma Formation
The retinoblastoma protein (pRb) is a cell cycle regulator inactivated in most human cancers. Loss of pRb function results from mutations in the gene coding for pRb or for any of its upstream regulators. Although pRb is predominantly known as a cell cycle repressor, our data point to additional pRb functions in cell adhesion. Our data show that pRb regulates the expression of a wide repertoire of cell adhesion genes and regulates the assembly of the adherens junctions required for cell adhesion. We conducted our studies in osteoblasts, which depend on both pRb and on cell-to-cell contacts for their differentiation and function. We generated knockout mice in which the RB gene was excised specifically in osteoblasts using the cre-lox P system and found that osteoblasts from pRb knockout mice did not assemble adherens junction at their membranes. pRb depletion in wild type osteoblasts using RNAi also disrupted adherens junctions. Microarrays comparing pRb-expressing and pRb-deficient osteoblasts showed that pRb controls the expression of a number of cell adhesion genes, including cadherins. Furthermore, pRb knockout mice showed bone abnormalities consistent with osteoblast adhesion defects. We also found that pRb controls the function of merlin, a well-known regulator of adherens junction assembly, by repressing Rac1 and its effector Pak1. Using qRT-PCR, immunoblots, co-immunoprecipitation assays, and immunofluorescent labeling, we observed that pRb loss resulted in Rac1 and Pak1 overexpression concomitant with merlin inactivation by Pak1, merlin detachment from the membrane, and adherens junction loss. Our data support a pRb function in cell adhesion while elucidating the mechanism for this function. Our work suggests that in some tumor types pRb inactivation results in both a loss of cell cycle control that promotes initial tumor growth as well as in a loss of cell-to-cell contacts, which contributes to later stages of metastasis
Abnormally Low Tender Problem in Public Works
The purpose of this paper is to determine the problems due to abnormally low tenders (ALTs) and to develop some methods for reducing the negative effects of ALTs. In this paper, the reasons of ALTs, recommendations to eliminate ALTs were investigated. According to this investigation, it was observed that results change due to different social structures of countries. In addition to this investigation, ALT evaluation questionnaire was prepared to determine reasons of ALTs. The ALT evaluation questionnaire reached to 400 companies. 18 questions were asked to the companies. Qualitative statistical methods were used to analyze correlation between variables. Comprehensive analysis was applied to the questionnaire and reasons behind ALTs were determined. Finally, some recommendations are proposed to professionals
Effect of smoking cessation on sexual functions in men aged 30 to 60 years
Purpose: We aimed to evaluate the effects of smoking cessation on the sexual functions in men aged 30 to 60 years
Investigation of Polymer Matrix Nano-Aluminum Composites with Pulsed Laser Heating by In-Situ TEM
The article of record as published may be found at https://doi.org/10.1002/prep.201900134Nanocomposites of aluminum and fluoropolymers react rapidly due to highly exothermic aluminum fluorination because of the high specific surface area nanoscale particles. In-situ transmission electron microscopy (TEM) techniques are invaluable for real time monitoring of the reactions in these systems at the nanoscale. Here, we investigated the reactions in nanoscale Al (nAl) and THV (terpolymer of tetrafluoroethylene, hexafluoropropylene, and vinylidene fluoride) and nAl-LDPE (low density polyethylene) composites, heated using a pulsed laser in a TEM. Results show that reactions are initiated at about 720 K, when THV starts to decompose, and proceed with the formation and growth of a hollow aluminum fluoride (AlF3) shell. Diffraction patterns revealed that this phase is the rare η-phase AlF3. In contrast, no reactions were observed in the inert nAl-LDPE composites. The experimental and theoretical results reveal that rapid pulsed laser heating and subsequent cooling of a nanoscale sample influences the phases that can form, and can be utilized to investigate other systems.This work was supported by the Young Investigator Program of Department of Defense Office of Naval Research (CBET-1437219)This work was supported by the Young Investigator Program of Department of Defense Office of Naval Research (CBET-1437219
PROSTHETIC COMPLICATIONS IN IMPLANT SUPPORTED FIXED PROSTHESIS: A FOUR YEAR MULTI-CENTER RETROSPECTIVE ANALYSIS
There have been many materials and application methods developed in order to overcome the complications related with implant supported restorations. Prosthetic failures still could emerge in spite of all advanced applications. One of the most common reasons of a prosthetic failure was shown to be the excessive occlusal forces. Excessive occlusal forces may cause prosthetic complications or component fractures as well as with progressive crestal bone loss. The aim of this retrospective study was to evaluate the prosthetic complications of the implant supported fixed prosthesis followed up to four years. A Cox proportional hazard regression analysis was used to evaluate possible associations. Long bridges and single tooth crowns were associated with porcelain fracture (p<0.01, HR: 4.46) and cement loosening (p<0.05 HR: 3.22) respectively. Care must be given to occlusal alignment of the implant supported crowns/bridges to overcome long-term complications. Key Words: Implant prosthesis, prosthetic failures, retrospective analysis
Validity and reliability of the Turkish version of the Self-reported Foot and Ankle Score in patients with foot or ankle pain
Objective: The aim of this study was to translate the Self-Reported Foot and Ankle Score (SEFAS) into Turkish and to determine the validity and reliability of the translated version in patients with foot or ankle pain