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Members of an online community peer-produce digital artifacts by negotiating different perspectives and personal knowledge bases. These negotiations are manifested in the temporal evolution of the peer-produced artifact. In this study, we conceptualize the evolution of a digital artifact as a trajectory in a feature space. Our theoretical frame suggests that, through negotiations, contributors’ actions “pull” the trajectory and shape its movement in the feature space. We hypothesize that the type of contributors that work on a focal article influences the extent to which that article’s trajectory explores alternative positions within that space, and that the trajectory’s exploration is, in turn, associated with the artifact’s quality. To test these hypotheses, we analyzed the trajectories of wiki articles drawn from two peer-production communities, Wikipedia and Wikia, tracking the evolution of 242 paired articles for over a decade during which the articles went through 536,745 revisions. We found that the contributors who are the most likely to increase the trajectory’s exploration are those that (1) return to work on the focal artifact and (2) are unregistered members in the broader online community. Further, our results show that the trajectory’s exploration has a curvilinear association with article quality, indicating that exploration contributes positively to quality, but that the effect is reversed when exploration exceeds a certain level. The insights derived from this study highlight the value of an artifact-centric approach to increasing our understanding of the dynamics underlying peer-production. [ABSTRACT FROM AUTHOR]

Background: There are various approaches in primary health care regarding the key role of nurses. This systematic review investigates the roles of nurses, as part of the family medicine team. Materials and Methods: All published articles related to the role of nurses in the family medicine team from January 2000 to March 2022 were the subjects of this study. The eligibility criteria included original articles published in English or Persian in the last two decades. International credible scholarly databases (PubMed, Scopus, Magiran, IranMedex, and SID) were searched using keywords and syntax. Some of the keywords included "Family Health Nurse," "Nurses in Primary Care," "Family Medicine," "Family Physician Care Program," "General Physician Program," "Role," and "Nurse." Data were extracted based on Sample, Phenomenon of Interest, Design, Evaluation, Research type (SPIDER) technique and reported based on the structure of Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). Results: Of 147 identified publications by the search strategy, eight eligible empirical studies were included. The results showed that besides providing nursing care, nurses play vital roles in communication and teamwork, assessment, securing health services relevant to communities' needs, education, empowerment, clinical practice, health promotion, prevention, reflective research practice, and counseling. Conclusions: This study identified different roles nurses could play in providing primary health care. These findings are helpful for the replanning or reform of primary health care in countries, which aimed to expand the Family Physician Program (FPP) in their countries, including Iran. [ABSTRACT FROM AUTHOR]

Cross-linked polyvinyl chloride (C-PVC) foams and their nanocomposite foams, containing Cloisite 30B nanoclays were prepared. The effects of compression molding pressure and time on the morphology and mechanical properties of different foams were studied. Increment of molding pressure led to higher apparent density, gel content, cell density, and expansion ratio, and wider cell size distribution, which improved the mechanical properties of the foams. Additionally, with the increasing of molding time, lower cell density and final expansion ratio, narrower cell size distribution, and higher gel content and mechanical properties could be obtained. Moreover, incorporation of Cloisite 30B nanoclay in a PVC matrix not only improved cellular microstructure and mechanical properties but also reduced water uptake ratios of nanocomposite foams. [ABSTRACT FROM AUTHOR]

Thermally and magnetically stimulated shape memory polyurethane (PU) nanocomposites were synthesized for intravascular stent applications. For this end, Fe3O4 magnetic nanoparticles (MNPs) were modified with octadecyl isocyanate (OD) to increase their affinity with the PU matrix by formation of the covalent urea linkages. The results showed that the OD‐grafted MNPs were replaced instead of carbonyl groups of polycaprolactone (PCL) soft segments in hydrogen bond formation with the urethane linkages. This led to higher phase separation degrees among the soft and hard phases, thereby PCL chains could reveal higher crystallization potential. Mechanical studies showed that the nanocomposites had high mechanical strength, Young's modulus, and elongation at break, which improve their practical applications. The nanocomposites showed thermo‐responsive shape memory behavior with a high shape recovery and shape fixity ratios due to the presence of the crystallizable PCL segments. The nanocomposite containing 10 wt% of the OD‐grafted MNPs could recover its original shape (during 90s) in a relatively weak alternating magnetic field (350 kHz and 12.9 kA/m). These results indicated that the prepared nanocomposites could be used to normalize the narrowed blood vessels through the remotely and magnetically‐controllable restricted shape recovery process. [ABSTRACT FROM AUTHOR]

Problem statement: The purpose of this study was to histopathology and biomechanics evaluate the effect of sodium fluoride on cancellous bone defect healing in rat model. Approach: The experiment was conducted on 40 male adult SD rats which were divided into four groups of control and experiments. After induction of general anesthesia, a hole in size of 2x3 mm in diameter and depth was made using a dental bit in the inner aspect of the between condyles of right femor. In all groups, defect was left untreated. Control group was given distilled water and the other three groups were exposed to fluoridated water at different concentrations (8, 30 and 60 mg F-/L). After 45 days all rats were sacrificed and the histopathological and biomechanical penetration tests of the distal femoral bone were performed. Results: In control group, defect seemed to be filled with adipous tissue and sparse hematogenic cells and in spite of a poor osteogenic activity and some osteoblasts could already be seen. In experiment groups, many osteoblasts groupings and young bone trabeculas increased in number and bone trabeculas more organized. Histopathologically findings show that 30 mg F-/L sodium fluoride in drinking water has been better effect than other groups. The mean load for fracturing in control group was 173.01 [+ or -] 23.05 and in experiment groups 8, 30 and 60mg were 177.31 [+ or -] 33.71, 181.90 [+ or -] 36.81 and 168.51 [+ or -] 54.35. Differences observed in biomechanically findings were significant between 30mg group and other groups (p Conclusion: The results of this study show that fluoride level at 30 mg [F.sup.-][L.sup.-1] in drinking water increases compressive strength of cancellous bone defect in healing process and could stimulate osteogenesis in femoral cancellous bone defect in rats. Key words: Sodium fluoride, cancellous bone, healing process, adult male rats, osteoblasts groupings, general anesthesia, biomechanics evaluate, osteoporotic patients, laboratory animal, INTRODUCTION Sodium fluoride in clinical use for treatment of osteoporosis and vertebral fractures (Demos et al., 2001; Apostolova and Brenne, 2010). Clinical studies have been shown that sodium fluoride is [...]

Shape memory polyurethane (SMPU)/graphene quantum dot nanoparticles (GQDs) nanofibers were prepared by electrospinning technique. Results show that the localization of GQD nanoparticles into the nanocomposite electrospun nanofibers has increased the nanofiber average diameter. An increment has been observed in the mechanical strength of nanocomposite nanofiber mats. More uniform and straight nanofibers have been obtained for PU-0.5% due to the relative electrical conductivity induced by the presence of GQD nanoparticles. Presence of crystallizable polycaprolactone (PCL) soft segment in PU structure induced shape memory potential in electrospun scaffolds. In vitro study showed PU-0.5% scaffold had good interaction with 3T3 fibroblast cells. [ABSTRACT FROM AUTHOR]