Digital literacy: a Palestinian refugee perspective

This paper is the first attempt to explore digital literacy in the specific context of the Palestinian refugee community in the Middle East by looking at the cultural specificity of digital literacy theorising and practice, by analysing current digital education policy in the countries hosting the Palestinian refugee community and by documenting the digital environment of the Palestinian refugee. It identifies the distance or deficit between the community’s current access to digital literacy education, appropriately defined, and its digital environment, needs and opportunities. Finally, the paper provides a brief agenda for further empirical research

Strategic Planning and its Relationship to School Performance among Private Secondary School Principals in the Capital Amman from the Teachers Point of View.

The study aims at identifying the relationship between strategic planning and school performance among private secondary school principals in Jordan from the teachers point of view. The researchers used the descriptive correlative approach, and the study sample consisted of (310) male and female teachers who work in private secondary schools in Marka District in the capital (Amman) in Jordan, they were selected by simple random sampling method. To achieve the objectives of the study, a questionnaire was developed that included (44) items. The results of the study showed that the degree of application of strategic planning, and the level of school performance was high,. They also showed that there were statistically significant differences due to the gender variable in favor of males, and the educational qualification variable in favor of the bachelor’s degree between the average responses of the study sample to the degree of strategic planning application. The results also showed that there were differences due to the gender variable in favor of males for the level of school performance. The study revealed a positive correlation between the degree of strategic planning application and the level of school performance The researcher recommended the need to continue developing and encouraging the application of strategic planning in order to reach the desired goals

Bacteria and Risk Factors of Acne Vulgaris in Northern West Bank, Palestine

Bacterial species and risk factors were examined in acne vulgaris patients inNorthern West Bank. Samples were obtained from face and upper trunk lesions of138 patients (age: 15-34 years) at Dermatology clinics. Samples were incubatedin blood agar plates under aerobic and anaerobic conditions. Patients were askedto answer a questionnaire and all provided written informed consent. Bacteriawere isolated from 88% of the patients including Propionibacterium acnes,Staphylococcus epidermidis and Staphylococcus aureus. Risk factors mentionedby patients included emotional stress, high temperature, sweating and localpressure. Chocolate, nuts and fatty food were mentioned as exacerbating, andvegetables and fruits as ameliorating foods for their acne, respectively. Resultsshow high correlation between acne and bacteria with no relation between riskfactors and specific bacterial strains.Keywords: Acne vulgaris, Palestine, West Bank, risk facto

Investigation of the Effect of Imatinib and Hydroxyurea Combination Therapy on Hematological Parameters and Gene Expression in Chronic Myeloid Leukemia (CML) Patients

(1) Background: Chronic myeloid leukemia is defined as the neoplastic development of mostly myeloid cells in the bone marrow. Several treatments, including chemotherapy, radiation, hormone treatment, and immunological therapy, can be used to control this condition. The therapeutic impact on leukemic individuals varies, and the response to therapy varies between patients due to disease heterogeneity. The primary goal of this study is to compare the effects of single and Imatinib (IM) and Hydroxyurea (HU) combined treatment on hematological parameters and gene expression in CML patients. (2) Methods: This study was conducted on 51 patients, with chronic myeloid leukemia, who were admitted to Al-Basher hospital in Amman, Jordan, for follow-up. Their hematological parameters were checked and gene expression was measured for (BCL2, PP2A, CIP2A, and WT1). (3) Results: The BCL2 gene was found to be less expressed in both IM and (HU + IM) treatments as compared to the HU group alone, while PP2A gene expression was raised. Such a thing indicates that the outcome of the combined therapy method is not ideal, since PP2A activation causes CML cells to move toward the blast crisis stage. Furthermore, CIP2A gene expression revealed that IM and (HU + IM) had the same therapeutic effect and were more successful in CML patients than HU alone. With regards to the treatment effect on hematological parameters, notably in CML patients in later stages, the combination therapy (HU + IM) raised lymphocyte count, indicating a greater response to the treatment. When compared to single medicines, the combination treatment reduced the proportion of neutrophils to normal reference ranges. Platelet counts, on the other hand, dramatically decreased in both IM and (HU + IM). (4) Conclusion: Because the studied genes (BCL2, PP2A, CIP2A, and WT1) are participating in cell proliferation and death, the findings show that the examined genes are significant to understand the efficacy of various therapies. Furthermore, it was found that there was a clear effect of the clinic-based strategic treatment on hematological indicators such as WBCs, lymphocytes, neutrophils, and platelet counts.Financial support was offered by Al-Ahliyya Amman University/Jordan. Open Access funding provided by the Qatar National Library (QNL)

Influence of cooling rate on residual stresses and chipping of porcelain on zirconia restorations

Cohesive failure of veneering porcelain, or chipping, has been recognised as the main disadvantage of zirconia-based restorations. This is believed to be due to a propensity to develop large thermal gradients within the veneering porcelain layer when the restoration cools from the sintering temperature to room temperature. Recent literature draws attention to the vastly different thermo-physical properties of zirconia compared to other core materials, in particular to its very low thermal conductivity. When the veneering porcelain in a zirconia restoration is cooled at a fast rate from above to below the glass transition temperature during the final firing cycle, high residual tensile zones develop within the veneering porcelain. These tensile zones act as weakness zones within the veneering porcelain that increase the risk of fracture. Thus slow cooling protocols are currently recommended for zirconia-based restorations to reduce the development of high residual tensile zones, and therefore reduce the risk of chipping fractures. In addition to the cooling rate, the thickness of the veneering porcelain has also been identified as a contributing factor by further increasing thermal gradients from the outer cooling surface of the veneering porcelain to the inner porcelain close to the zirconia core. So far there are no studies that have integrated the relationship between veneering porcelain thickness, cooling rates, and differences in surface residual stresses on anatomical zirconia molar crowns. This research is composed of three parts: Part I (chapter 2) is a comprehensive review of the published clinical trials on zirconia-based restorations. Part II (chapter 3) investigates residual stresses on the cusp tips of fast cooled and slow cooled zirconia molar crowns with various cusp thicknesses. In part III (chapter 4), fast and slow cooled molar zirconia crowns were tested under static loading-to-failure in order to qualitatively compare differences in failure modes and fracture features using fractographic analysis. Furthermore, quantitative assessment of the maximum load-to-failure in both groups was also undertaken to establish any strengthening effects developed by the tempering process on the fast cooled zirconia crowns. Methods & Materials: Part I: A comprehensive review of in vivo trials involving zirconia-based restorations featuring in MEDLINE and PubMed between 1950 and June 2011 was completed. A manual hand search of relevant dental journals was also completed. Part II: Six identical Procera zirconia copings (Procera, Nobel Biocare), pressed with IPS e.max ZirPress (Ivoclar Vivadent) and layered with IPS e.max Ceram (Ivoclar Vivadent) based on a mandibular molar form, were divided into 3 groups to the following flattened cusp heights: 1mm, 2mm, and 3mm. Half the samples were slow cooled during the final glazing cycle and the other half fast cooled. To determine residual surface stresses, 4 cusps on each crown were indented using a Vickers microhardness indenter under a load of 10N. Crack measurements were made on calibrated photographic images taken immediately after each indentation using an optical light microscope and a mounted digital camera. Part III: Ten identical Procera zirconia copings, pressed with IPS e.max ZirPress based on a mandibular molar form, were divided into 2 groups. Half the samples were slow cooled during the final glazing cycle and the other half fast cooled. Following cementation of the zirconia crowns to epoxy resin abutments using Rely-X Unicem (3M ESPE), the disto-lingual cusp of each crown was subjected to a simulated occlusal adjustment prior to loading-to-failure using a universal testing machine. This was done using a 4mm diameter stainless steel ball at a cross-head speed of 0.1mm/min. Qualitative fracture analysis of each fractured sample was initially carried out by a visual interpretation. Two samples from each group were chosen for examination by scanning electron microscopy. Results: Part I: Nineteen clinical trials involving zirconia-based restorations were found. Fifteen were conducted on fixed partial dentures, and 4 on single crowns, of which 14 were based on soft-milled zirconia, and 5 on hard-milled zirconia. Chipping of veneering porcelain was a common occurrence, and framework fracture was only observed in soft-milled zirconia. Part II: Residual surface compressive stresses were recorded for all fast cooled crowns. In contrast, surface residual tensile stresses were recorded on the cusp tips of all slow cooled zirconia crowns. The highest residual compressive stresses were found on fast cooled 1mm thick porcelain cusps (-13.08 MPa) which was significantly higher than the 2mm and 3mm fast cooled crowns (P 0.05). The highest residual tensile stresses were recorded for the 2mm thick cusp crown in the slow cooled group (5.36 MPa), however there were no significant statistical differences in the various cusp heights for the slow cooled group (P = 0.05). Part III: The average maximum load-to-failure for the fast cooled group was slightly lower than that recorded for the slow cooled group (901.54 N and 1013.00 N respectively), however this difference was not statistically significant (P > 0.05). Fractographic analyses confirmed the presence of differential residual stress profiles in the veneering porcelain of fast cooled zirconia crowns by the presence of high concentrations of twist hackles, compression curls, and multi-plane fractures, which were not observed in the slow cooled zirconia crowns. Conclusions: Part I: Based on the limited number of short-term in vivo studies involving zirconia-based restorations, there is a high incidence of veneering porcelain chipping, affecting every brand of zirconia, in both single crowns and fixed partial dentures. These clinical trials report on restorations fabricated before the implementation of the modified manufacturers’ recommendation of slow cooling zirconia-based restorations. Further long-term prospective studies that address the cooling protocol around the glass transition temperatures of the veneering porcelains are necessary to establish the best manufacturing process for zirconia-based restorations. Part II: The results confirm that residual surface compressive stresses at the cusp tips were significantly higher in the fast cooled crowns than the slow cooled crowns. Increasing the thickness of the veneering porcelain in zirconia molar crowns did not cause an increase in the resultant surface residual stresses possibly due to variation in the anatomical contours of veneering porcelains. Moreover, a reverse trend was found when decreasing the thickness of veneering porcelain from 2mm to 1mm cusp tips in fast cooled crowns. Part III: Fast cooling zirconia crowns did not improve fracture resistance under static loading-to-failure. In addition, crack propagation and fracture patterns were highly influenced by the cooling protocols used

Influence of cooling rate on residual stresses and chipping of porcelain on zirconia restorations

Cohesive failure of veneering porcelain, or chipping, has been recognised as the main disadvantage of zirconia-based restorations. This is believed to be due to a propensity to develop large thermal gradients within the veneering porcelain layer when the restoration cools from the sintering temperature to room temperature. Recent literature draws attention to the vastly different thermo-physical properties of zirconia compared to other core materials, in particular to its very low thermal conductivity. When the veneering porcelain in a zirconia restoration is cooled at a fast rate from above to below the glass transition temperature during the final firing cycle, high residual tensile zones develop within the veneering porcelain. These tensile zones act as weakness zones within the veneering porcelain that increase the risk of fracture. Thus slow cooling protocols are currently recommended for zirconia-based restorations to reduce the development of high residual tensile zones, and therefore reduce the risk of chipping fractures. In addition to the cooling rate, the thickness of the veneering porcelain has also been identified as a contributing factor by further increasing thermal gradients from the outer cooling surface of the veneering porcelain to the inner porcelain close to the zirconia core. So far there are no studies that have integrated the relationship between veneering porcelain thickness, cooling rates, and differences in surface residual stresses on anatomical zirconia molar crowns. This research is composed of three parts: Part I (chapter 2) is a comprehensive review of the published clinical trials on zirconia-based restorations. Part II (chapter 3) investigates residual stresses on the cusp tips of fast cooled and slow cooled zirconia molar crowns with various cusp thicknesses. In part III (chapter 4), fast and slow cooled molar zirconia crowns were tested under static loading-to-failure in order to qualitatively compare differences in failure modes and fracture features using fractographic analysis. Furthermore, quantitative assessment of the maximum load-to-failure in both groups was also undertaken to establish any strengthening effects developed by the tempering process on the fast cooled zirconia crowns. Methods & Materials: Part I: A comprehensive review of in vivo trials involving zirconia-based restorations featuring in MEDLINE and PubMed between 1950 and June 2011 was completed. A manual hand search of relevant dental journals was also completed. Part II: Six identical Procera zirconia copings (Procera, Nobel Biocare), pressed with IPS e.max ZirPress (Ivoclar Vivadent) and layered with IPS e.max Ceram (Ivoclar Vivadent) based on a mandibular molar form, were divided into 3 groups to the following flattened cusp heights: 1mm, 2mm, and 3mm. Half the samples were slow cooled during the final glazing cycle and the other half fast cooled. To determine residual surface stresses, 4 cusps on each crown were indented using a Vickers microhardness indenter under a load of 10N. Crack measurements were made on calibrated photographic images taken immediately after each indentation using an optical light microscope and a mounted digital camera. Part III: Ten identical Procera zirconia copings, pressed with IPS e.max ZirPress based on a mandibular molar form, were divided into 2 groups. Half the samples were slow cooled during the final glazing cycle and the other half fast cooled. Following cementation of the zirconia crowns to epoxy resin abutments using Rely-X Unicem (3M ESPE), the disto-lingual cusp of each crown was subjected to a simulated occlusal adjustment prior to loading-to-failure using a universal testing machine. This was done using a 4mm diameter stainless steel ball at a cross-head speed of 0.1mm/min. Qualitative fracture analysis of each fractured sample was initially carried out by a visual interpretation. Two samples from each group were chosen for examination by scanning electron microscopy. Results: Part I: Nineteen clinical trials involving zirconia-based restorations were found. Fifteen were conducted on fixed partial dentures, and 4 on single crowns, of which 14 were based on soft-milled zirconia, and 5 on hard-milled zirconia. Chipping of veneering porcelain was a common occurrence, and framework fracture was only observed in soft-milled zirconia. Part II: Residual surface compressive stresses were recorded for all fast cooled crowns. In contrast, surface residual tensile stresses were recorded on the cusp tips of all slow cooled zirconia crowns. The highest residual compressive stresses were found on fast cooled 1mm thick porcelain cusps (-13.08 MPa) which was significantly higher than the 2mm and 3mm fast cooled crowns (P 0.05). The highest residual tensile stresses were recorded for the 2mm thick cusp crown in the slow cooled group (5.36 MPa), however there were no significant statistical differences in the various cusp heights for the slow cooled group (P = 0.05). Part III: The average maximum load-to-failure for the fast cooled group was slightly lower than that recorded for the slow cooled group (901.54 N and 1013.00 N respectively), however this difference was not statistically significant (P > 0.05). Fractographic analyses confirmed the presence of differential residual stress profiles in the veneering porcelain of fast cooled zirconia crowns by the presence of high concentrations of twist hackles, compression curls, and multi-plane fractures, which were not observed in the slow cooled zirconia crowns. Conclusions: Part I: Based on the limited number of short-term in vivo studies involving zirconia-based restorations, there is a high incidence of veneering porcelain chipping, affecting every brand of zirconia, in both single crowns and fixed partial dentures. These clinical trials report on restorations fabricated before the implementation of the modified manufacturers’ recommendation of slow cooling zirconia-based restorations. Further long-term prospective studies that address the cooling protocol around the glass transition temperatures of the veneering porcelains are necessary to establish the best manufacturing process for zirconia-based restorations. Part II: The results confirm that residual surface compressive stresses at the cusp tips were significantly higher in the fast cooled crowns than the slow cooled crowns. Increasing the thickness of the veneering porcelain in zirconia molar crowns did not cause an increase in the resultant surface residual stresses possibly due to variation in the anatomical contours of veneering porcelains. Moreover, a reverse trend was found when decreasing the thickness of veneering porcelain from 2mm to 1mm cusp tips in fast cooled crowns. Part III: Fast cooling zirconia crowns did not improve fracture resistance under static loading-to-failure. In addition, crack propagation and fracture patterns were highly influenced by the cooling protocols used

Basin of Attraction through Invariant Curves and Dominant Functions

We study a second-order difference equation of the form zn+1=znF(zn-1)+h, where both F(z) and zF(z) are decreasing. We consider a set of invariant curves at h=1 and use it to characterize the behaviour of solutions when h>1 and when 0<h<1. The case h>1 is related to the Y2K problem. For 0<h<1, we study the stability of the equilibrium solutions and find an invariant region where solutions are attracted to the stable equilibrium. In particular, for certain range of the parameters, a subset of the basin of attraction of the stable equilibrium is achieved by bounding positive solutions using the iteration of dominant functions with attracting equilibria