Development and Implementation of a New Technique to Study (p,α) Reactions Relevant to Nucleosynthesis in Binary Systems

The accurate determination of the strengths and energies of resonances in (p,alpha) reactions is important for understanding the influence of reaction cycles to element synthesis in many astrophysical environments. Thus far, (p,alpha) studies in inverse kinematics have employed solid polypropylene targets. These are not always advantageous, especially when the energy loss of the incoming beam in the solid target is significantly larger than the resonance width. At the Holifield Radioactive Ion Beam Facility, a new technique has been developed for measuring the strengths and energies of (p,alpha) reactions. In this technique, a large differentially-pumped scattering chamber is filled with hydrogen gas at pressures up to 4 Torr. No windows or foils obstruct the incoming beam and reaction products are detected in coincidence by two silicon strip arrays. The vertex of the (p,alpha) reaction is determined from the known kinematics of the alpha particle and heavy recoil. This new technique was applied to study the strength of the 183 keV resonance in 17O(p,alpha)14N reaction that was previously reported to significantly increase the reaction rate at nova temperatures and decrease 18F production by as much as a factor of 10 in low-mass ONeMg novae. This larger strength was confirmed using the new technique and nova simulations showed a substantial decrease in 18F production in lower-mass novae though a much smaller effect was seen in higher-mass novae. Low-energy resonances in 31P(p,alpha)28Si and 35Cl(p,alpha)32S were also studied using the same technique in order to gain a better understanding of reaction cycling in the Si-Ar region. Resonance strengths at ECM = 599 and 622 keV in 31P(p,alpha)28Si were measured as well as the ECM = 611 keV resonance in 35Cl(p,alpha)32S, the lowest energy that any resonance in this reaction has been observed. The strengths of these resonances were found to be lower than previously determined through indirect methods, resulting in weak cycling in the Si-Ar region

Expression of an innate immune element (mouse hepcidin-1) in baculovirus expression system and the comparison of its function with synthetic human hepcidin-25

Hepcidin is an innate immune element which decreases the iron absorption from diet and iron releasing from macrophage cell. In contrast to the chemical iron chelators, there has been limited effort applied to the specific use of hepcidin as a new drug for decreasing the iron overload. Hepcidin is produced in different biological systems. For instance, E-coli is used for human hepcidin expression, however, post-translational modification is impaired. We have used a simple baculovirus expression system (BES) to improve the hepcidin folding and activity. Hepcidin Messenger Ribonucleic acid (mRNA) was isolated from mouse liver cells and its complementary Deoxyribonucleic acid (cDNA) was produced and amplified. PFastBac HTB vector was used for recombinant bacmid production. Recombinant baculovirus was produced using SF-9 cell line. The mouse hepcidin-1 protein was expressed in a large quantity and functional tests were performed for this recombinant peptide. The yield of hepcidin in BES was 20 μg/mL and anti-histidine (anti-His) tag antibody was used for the confirmation of hepcidin on western blot nitrocellulose paper. Functional tests showed that mouse hepcidin accumulates iron in the macrophage cell line J774A.1 up to 63%. In addition, our data showed that the mouse hepcidin-1 has less toxicity compared to the synthetic human hepcidin-25 (p = 0.000). © 2011 by School of Pharmacy

How human gait responds to muscle impairment in total knee arthroplasty patients: Muscular compensations and articular perturbations

Post-surgical muscle weakness is prevalent among patients who undergo total knee arthroplasty (TKA). We conducted a probabilistic multi-body dynamics (MBD) to determine whether and to what extent habitual gait patterns of TKA patients may accommodate strength deficits in lower extremity muscles. We analyzed muscular and articular compensations in response to various muscle impairments, and the minimum muscle strength requirements needed to preserve TKA gait patterns in its habitual status. Muscle weakness was simulated by reducing the strength parameter of muscle models in MBD analysis. Using impaired models, muscle and joint forces were calculated and compared versus those from baseline gait i.e. TKA habitual gait before simulating muscle weakness. Comparisons were conducted using a relatively new statistical approach for the evaluation of gait waveforms, i.e. Spatial Parameter Mapping (SPM). Principal component analysis was then conducted on the MBD results to quantify the sensitivity of every joint force component to individual muscle impairment. The results of this study contain clinically important, although preliminary, suggestions. Our findings suggested that: (1) hip flexor and ankle plantar flexor muscles compensated for hip extensor weakness; (2) hip extensor, hip adductor and ankle plantar flexor muscles compensated for hip flexor weakness; (3) hip and knee flexor muscles responded to hip abductor weakness; (4) knee flexor and hip abductor balanced hip adductor impairment; and (5) knee extensor and knee flexor weakness were compensated by hip extensor and hip flexor muscles. Future clinical studies are required to validate the results of this computational study

Mechanical properties of calvarial bones in a mouse model for craniosynostosis

The mammalian cranial vault largely consists of five flat bones that are joined together along their edges by soft fibrous tissues called sutures. Premature closure of the cranial sutures, craniosynostosis, can lead to serious clinical pathology unless there is surgical intervention. Research into the genetic basis of the disease has led to the development of various animal models that display this condition, e.g. mutant type Fgfr2C342Y/+ mice which display early fusion of the coronal suture (joining the parietal and frontal bones). However, whether the biomechanical properties of the mutant and wild type bones are affected has not been investigated before. Therefore, nanoindentation was used to compare the elastic modulus of cranial bone and sutures in wild type (WT) and Fgfr2C342Y/+mutant type (MT) mice during their postnatal development. Further, the variations in properties with indentation position and plane were assessed. No difference was observed in the elastic modulus of parietal bone between the WT and MT mice at postnatal (P) day 10 and 20. However, the modulus of frontal bone in the MT group was lower than the WT group at both P10 (1.39±0.30 vs. 5.32±0.68 GPa; p<0.05) and P20 (5.57±0.33 vs. 7.14±0.79 GPa; p<0.05). A wide range of values was measured along the coronal sutures for both the WT and MT samples, with no significant difference between the two groups. Findings of this study suggest that the inherent mechanical properties of the frontal bone in the mutant mice were different to the wild type mice from the same genetic background. These differences may reflect variations in the degree of biomechanical adaptation during skull growth, which could have implications for the surgical management of craniosynostosis patients

The Role of Faculty in Institutional Decision Making

Faculty participation in the governance of institutions of higher education is a critical element in the founding structure for American universities. This expectation and willingness to participate has been affected by contemporary factors such as accountability, shifting priorities among teaching, service, and research, corporatization, and retrenchment. Comparing faculty perceptions between Dykes 1968 landmark study and faculty today is important for determining if there has been a change in faculty’s view of their role. The purpose of this study was to explore faculty perceptions of their ideal and actual governance role within higher education and their satisfaction in those roles. The findings of this study of faculty’s ideal role in decisions were in line with those found in Dykes study. Across all five areas of faculty role in decision making, the ideal involvement scores were significantly higher than the actual involvement scores with retrenchment decisions having the largest discrepancy. Based on the findings of this study, it is reasonable to conclude that the desire for faculty to take an active role in institutional governance is present. The barriers to participation continue to be strong and include most prominently an increasing focus on research and the corporatization of higher education

Application of Far Cortical Locking Technology in Periprosthetic Femoral Fracture Fixation: A Biomechanical Study

© 2016 Elsevier Inc. Background Lack of fracture movement could be a potential cause of periprosthetic femoral fracture (PFF) fixation failures. This study aimed to test whether the use of distal far cortical locking screws reduces the overall stiffness of PFF fixations and allows an increase in fracture movement compared to standard locking screws while retaining the overall strength of the PFF fixations. Methods Twelve laboratory models of Vancouver type B1 PFFs were developed. In all specimens, the proximal screw fixations were similar, whereas in 6 specimens, distal locking screws were used, and in the other six specimens, far cortical locking screws. The overall stiffness, fracture movement, and pattern of strain distribution on the plate were measured in stable and unstable fractures under anatomic 1-legged stance. Specimens with unstable fracture were loaded to failure. Results No statistical difference was found between the stiffness and fracture movement of the two groups in stable fractures. In the unstable fractures, the overall stiffness and fracture movement of the locking group was significantly higher and lower than the far cortical group, respectively. Maximum principal strain on the plate was consistently lower in the far cortical group, and there was no significant difference between the failure loads of the 2 groups. Conclusion The results indicate that far cortical locking screws can reduce the overall effective stiffness of the locking plates and increase the fracture movement while maintaining the overall strength of the PFF fixation construct. However, in unstable fractures, alternative fixation methods, for example, long stem revision might be a better option

Contribution of geometric design parameters to knee implant performance: Conflicting impact of conformity on kinematics and contact mechanics

Background: Articular geometry of knee implant has a competing impact on kinematics and contact mechanics of total knee arthroplasty (TKA) such that geometry with lower contact pressure will impose more constraints on knee kinematics. The geometric parameters that may cause this competing effect have not been well understood. This study aimed to quantify the underlying relationships between implant geometry as input and its performance metrics as output. Methods: Parametric dimensions of a fixed-bearing cruciate retaining implant were randomized to generate a number of perturbed implant geometries. Performance metrics (i.e., maximum contact pressure, anterior–posterior range of motion [A-P ROM] and internal–external range of motion [I-E ROM]) of each randomized design were calculated using finite element analysis. The relative contributions of individual geometric variables to the performance metrics were then determined in terms of sensitivity indices (SI). Results: The femoral and tibial distal or posterior radii and femoral frontal radius are the key parameters. In the sagittal plane, distal curvature of the femoral and tibial influenced both contact pressure, i.e., SI = 0.57; SI = 0.65, and A-P ROM, i.e., SI = 0.58; SI = 0.6, respectively. However, posterior curvature of the femoral and tibial implants had a smaller impact on the contact pressure, i.e., SI = 0.31; SI = 0.23 and a higher impact on the I-E ROM, i.e., SI = 0.72; SI = 0.58. It is noteworthy that in the frontal plane, frontal radius of the femoral implant impacted both contact pressure (SI = 0.38) and I-E ROM (SI = 0.35). Conclusion: Findings of this study highlighted how changes in the conformity of the femoral and tibial can impact the performance metrics

Investigating the relationship between auditor tenure and the size of the audit firm with earnings management in pharmaceutical companies listed in Tehran Stock Exchange

Earnings management and related research has been always of interest in accounting researches. Most corporate managers use different methods of earnings management to reduce risk and smooth earning in various periods, meanwhile, the auditors are expected to be able to prevent the occurrence of this phenomenon; therefore, the present study is designed and implemented to investigate the relationship between tenure and the audit firm size and earnings management. The statistical population consists of pharmaceutical companies listed in Tehran Stock Exchange and the sample was selected to be 25 pharmaceutical companies using the systematic elimination method. The time realm of this study is 2005 to 2010. The objective of the present research is applied and it is descriptive – correlational in terms of implementation and data were analyzed using multivariate regression based on panel data method. Although research findings indicate that there is no relationship between auditor tenure and earnings management, but increase in the size of the audit firm reduces management flexibility in the use of discretionary accruals for earnings management

Investigating the relationship between auditor tenure and the size of the audit firm with earnings management in pharmaceutical companies listed in Tehran Stock Exchange

Earnings management and related research has been always of interest in accounting researches. Most corporate managers use different methods of earnings management to reduce risk and smooth earning in various periods, meanwhile, the auditors are expected to be able to prevent the occurrence of this phenomenon; therefore, the present study is designed and implemented to investigate the relationship between tenure and the audit firm size and earnings management. The statistical population consists of pharmaceutical companies listed in Tehran Stock Exchange and the sample was selected to be 25 pharmaceutical companies using the systematic elimination method. The time realm of this study is 2005 to 2010. The objective of the present research is applied and it is descriptive – correlational in terms of implementation and data were analyzed using multivariate regression based on panel data method. Although research findings indicate that there is no relationship between auditor tenure and earnings management, but increase in the size of the audit firm reduces management flexibility in the use of discretionary accruals for earnings management