Comparing stress distribution, strain, and total deformation in contact surface for the three types of rack and pinion

Used helical gear in many engineering applications as in rack and pinion. This paper shows a study of three types of rack and pinion, these types used helical gear, the first type is single gear, the second type is double gear, and the third is herringbone gear. The research explained the distribution of stresses, strains, and elastic deformation in the contact area between all types of the rack and pinion. Some important conclusions were presented for the purpose to can be used in design such as choose a high-strength material for gear with the specified helix angle, and selected a larger face width in the gear shape is preferred, total deformation varies from one type of rack pinion gears to another. The results show, total deformation varies from one type of rack pinion gears to another, but It seems that the single helical gear elastic deformation is high value and the rack-pinion (herringbone gears). The best of the three types in this research is according to the values of the distribution of stresses, strains, and elastic deformations

Mechanical Properties Comparison of Four Models, Failure Theories Study and Estimation of Thermal Expansion Coefficients for Artificial E-glass Polyester Composite

In this paper, the mechanical properties of artificial E-glass reinforced polyester composite were evaluated; the elastic properties and the strength of the composite were measured experimentally by tensile tests and then compared with the predicted values by theoretical four micromechanical constitutive models. The strength of the composite lamina and laminates were also determined experimentally and compared with five widely used theoretical failure theories. The lamination theory was also used to determine the strength of laminates by applying Hill- Tsai failure criterion. The theoretical models showed that the composite stiffness increases with increasing the fibre volume fraction and the volume fraction which gave the best fit to the experimental results of elastic modulus (E1) corresponds to volume fraction (Vf) equal 0.37. The stiffness of a unidirectional lamina depends on the fiber orientation relative to the off-axis load direction, and it drops sharply as the fiber alignment angle increases. In addition, the prediction of thermal expansion coefficients of composite is carried out in the present analysis, whereas the values of the coefficient that estimated to be based on the mechanical properties of the certain composite theoretically and experimentally

Side lobe reduction in array antenna by using novel design of EBG

A novel design of EBG is used to replace the mushroom like EBG for surrounding the array patch antenna. In order to improve its radiation performances, Electromagnetic band stop for reducing the surface waves effects is presented. The novel design of Triple Side Slotted EBG (TSSEBG) showed an improvement in the antenna efficiency, directivity and gain as compared to the reference antenna without using EBG, due to reduce the surface waves effects which leads to decrease the side lobes. TSSEBG has been introduced by some modifications in conventional mushroom-like EBG structure. Reducing the complexity was achieved by reducing the number of unit cells and vias, in case of used TSSEBG instead of mushroom like EBG. Additionally, the TSSEBG provided triple band gap compared with mushroom like EBG structure which had only one band gap frequency at 6 GHz. The placement of TSSEBG is a flexible structure which provides a good choice in the antenna applications. The simulation results of array patch antenna with and without mushroom like EBG and TSSEBG are arranged in Table 1. This structure has vast applications in satellite communications

Causes of elective cesarean delivery on maternal request in Aljouf, Saudi Arabia

Background: Recently observed there is a steadily higher rate of cesarean delivery worldwide mostly due to the increasing number of women requesting an elective cesarean section on maternal request without valid indication. The aim of the study was to determine the causes of elective cesarean delivery on maternal requests in Aljouf Saudi Arabia.Methods: This was a descriptive cross-sectional study and data was evaluated by completing seven questionnaires and interviews with laboratory reports who were admitted for cesarean delivery at the Obstetrics department of Maternity and Children Hospital (MCH) Aljouf, Saudi Arabia from January 2020 to December 2020. A total of 141 Saudi women of age between 18 and over 35 years were enrolled, including those who have singleton pregnancy, no complications during pregnancy, and no medical indication for cesarean delivery.Results: 141 women reported willingness to request cesarean delivery. The mean systolic 120±6.23, diastolic 75±2.45 blood pressure mm of Hg, and fasting blood sugar level 4.1±1.1 mmol/l have been found within the normal limit. The ultrasound (US) confirmed singleton pregnancy without any abnormalities.  Data reveals that common causes of elective cesarean section on maternal request to avoid the episiotomy 77.3%, fear of labor pain 69.5%, trauma to the vagina 79.4%, uncertainty about timing 61.7%, losing a baby during vaginal delivery 54.6%, experience other members 41.8%, the risk for baby 39%, prolapse or incontinence24.1%, unsatisfactory sexual intercourse 17.7% and the undesirable experience of the previous vaginal delivery 12%.Conclusions: Maternal request for cesarean delivery is considered one of the reasons for increasing the rate of cesarean delivery in Saudi Arabia. To avoid the episiotomy and fear of labor pain may strong causes for choosing cesarean delivery

Circulating and intraprostatic sex steroid hormonal profiles in relation to male pattern baldness and chest hair density among men diagnosed with localized prostate cancers

Background: Prospective cohort studies of circulating sex steroid hormones and prostate cancer risk have not provided a consistent association, despite evidence from animal and clinical studies. However, studies using male pattern baldness as a proxy of early-life or cumulative androgen exposure have reported significant associations with aggressive and fatal prostate cancer risk. Given that androgens underlie the development of patterned hair loss and chest hair, we assessed whether these two dermatological characteristics were associated with circulating and intraprostatic concentrations of sex steroid hormones among men diagnosed with localized prostate cancer. Methods:We included 248 prostate cancer patients from the NCI Prostate Tissue Study, who answered surveys and provided a pre-treatment blood sample as well as fresh frozen adjacent normal prostate tissue. Male pattern baldness and chest hair density were assessed by trained nurses before surgery. General linear models estimated geometric means and 95% confidence intervals (95%CIs) of each hormone variable by dermatological phenotype with adjustment for potential confounding variables. Subgroup analyses were performed by Gleason score (\u3c7 vs ≥7) and race (European American vs. African American). Results: We found strong positive associations of balding status with serum testosterone, dihydrotestosterone (DHT), estradiol, and sex hormone-binding globulin (SHBG), and a weak association with elevated intraprostatic testosterone. Conversely, neither circulating nor intraprostatic sex hormones were statistically significantly associated with chest hair density. Age-adjusted correlation between binary balding status and three-level chest hair density was weak (r = 0.05). There was little evidence to suggest that Gleason score or race modified these associations. Conclusions: This study provides evidence that balding status assessed at a mean age of 60 years may serve as a clinical marker for circulating sex hormone concentrations. The weak-to-null associations between balding status and intraprostatic sex hormones reaffirm differences in organ-specific sex hormone metabolism, implying that other sex steroid hormone-related factors (eg, androgen receptor) play important roles in organ-specific androgenic actions, and that other overlapping pathways may be involved in associations between the two complex conditions

MAP Kinase Phosphatase-2 Plays a Critical Role in Response to Infection by Leishmania mexicana

In this study we generated a novel dual specific phosphatase 4 (DUSP4) deletion mouse using a targeted deletion strategy in order to examine the role of MAP kinase phosphatase-2 (MKP-2) in immune responses. Lipopolysaccharide (LPS) induced a rapid, time and concentration-dependent increase in MKP-2 protein expression in bone marrow-derived macrophages from MKP-2+/+ but not from MKP-2−/− mice. LPS-induced JNK and p38 MAP kinase phosphorylation was significantly increased and prolonged in MKP-2−/− macrophages whilst ERK phosphorylation was unaffected. MKP-2 deletion also potentiated LPS-stimulated induction of the inflammatory cytokines, IL-6, IL-12p40, TNF-α, and also COX-2 derived PGE2 production. However surprisingly, in MKP-2−/− macrophages, there was a marked reduction in LPS or IFNγ-induced iNOS and nitric oxide release and enhanced basal expression of arginase-1, suggesting that MKP-2 may have an additional regulatory function significant in pathogen-mediated immunity. Indeed, following infection with the intracellular parasite Leishmania mexicana, MKP-2−/− mice displayed increased lesion size and parasite burden, and a significantly modified Th1/Th2 bias compared with wild-type counterparts. However, there was no intrinsic defect in MKP-2−/− T cell function as measured by anti-CD3 induced IFN-γ production. Rather, MKP-2−/− bone marrow-derived macrophages were found to be inherently more susceptible to infection with Leishmania mexicana, an effect reversed following treatment with the arginase inhibitor nor-NOHA. These findings show for the first time a role for MKP-2 in vivo and demonstrate that MKP-2 may be essential in orchestrating protection against intracellular infection at the level of the macrophage

Circulating and intraprostatic sex steroid hormonal profiles in relation to male pattern baldness and chest hair density among men diagnosed with localized prostate cancers

Background: Prospective cohort studies of circulating sex steroid hormones and prostate cancer risk have not provided a consistent association, despite evidence from animal and clinical studies. However, studies using male pattern baldness as a proxy of early-life or cumulative androgen exposure have reported significant associations with aggressive and fatal prostate cancer risk. Given that androgens underlie the development of patterned hair loss and chest hair, we assessed whether these two dermatological characteristics were associated with circulating and intraprostatic concentrations of sex steroid hormones among men diagnosed with localized prostate cancer. Methods:We included 248 prostate cancer patients from the NCI Prostate Tissue Study, who answered surveys and provided a pre-treatment blood sample as well as fresh frozen adjacent normal prostate tissue. Male pattern baldness and chest hair density were assessed by trained nurses before surgery. General linear models estimated geometric means and 95% confidence intervals (95%CIs) of each hormone variable by dermatological phenotype with adjustment for potential confounding variables. Subgroup analyses were performed by Gleason score (\u3c7 vs ≥7) and race (European American vs. African American). Results: We found strong positive associations of balding status with serum testosterone, dihydrotestosterone (DHT), estradiol, and sex hormone-binding globulin (SHBG), and a weak association with elevated intraprostatic testosterone. Conversely, neither circulating nor intraprostatic sex hormones were statistically significantly associated with chest hair density. Age-adjusted correlation between binary balding status and three-level chest hair density was weak (r = 0.05). There was little evidence to suggest that Gleason score or race modified these associations. Conclusions: This study provides evidence that balding status assessed at a mean age of 60 years may serve as a clinical marker for circulating sex hormone concentrations. The weak-to-null associations between balding status and intraprostatic sex hormones reaffirm differences in organ-specific sex hormone metabolism, implying that other sex steroid hormone-related factors (eg, androgen receptor) play important roles in organ-specific androgenic actions, and that other overlapping pathways may be involved in associations between the two complex conditions

Relationships between Circulating and Intraprostatic Sex Steroid Hormone Concentrations

Background: Sex hormones have been implicated in prostate carcinogenesis, yet epidemiologic studies have not provided substantiating evidence. We tested the hypothesis that circulating concentrations of sex steroid hormones reflect intraprostatic concentrations using serum and adjacent microscopically verified benign prostate tissue from prostate cancer cases.Methods: Incident localized prostate cancer cases scheduled for surgery were invited to participate. Consented participants completed surveys, and provided resected tissues and blood. Histologic assessment of the ends of fresh frozen tissue confirmed adjacent microscopically verified benign pathology. Sex steroid hormones in sera and tissues were extracted, chromatographically separated, and then quantitated by radioimmunoassays. Linear regression was used to account for variations in intraprostatic hormone concentrations by age, body mass index, race, and study site, and subsequently to assess relationships with serum hormone concentrations. Gleason score (from adjacent tumor tissue), race, and age were assessed as potential effect modifiers.Results: Circulating sex steroid hormone concentrations had low-to-moderate correlations with, and explained small proportions of variations in, intraprostatic sex steroid hormone concentrations. Androstane-3α,17β-diol glucuronide (3α-diol G) explained the highest variance of tissue concentrations of 3α-diol G (linear regression r2 = 0.21), followed by serum testosterone and tissue dihydrotestosterone (r2 = 0.10), and then serum estrone and tissue estrone (r2 = 0.09). There was no effect modification by Gleason score, race, or age.Conclusions: Circulating concentrations of sex steroid hormones are poor surrogate measures of the intraprostatic hormonal milieu.Impact: The high exposure misclassification provided by circulating sex steroid hormone concentrations for intraprostatic levels may partly explain the lack of any consistent association of circulating hormones with prostate cancer risk. Cancer Epidemiol Biomarkers Prev; 26(11); 1660-6. ©2017 AACR