Automated Source-Detector Positioner for Radiation Detection

The Nuclear Engineering Department at Virginia Commonwealth University has an unmet need for an automated source detector positioner for radiation detection experiments that are carried out in lab work. During radiation data collection in radiation detection systems it is of the utmost importance that radioactive samples are positioned and moved with the highest degree of precision possible. This high degree of precision allows for more meaningful data to be collected. The current methods employed by the Nuclear Engineering Department are not as accurate as they can be due to the fact the the current detection systems are manual. Furthermore they are aligned only by sight and have fixed shelving positions. The figure below is the solution to this issue: An automated Source-Detector Positioner for Radiation Detection. This detection system has been design to have a low tolerance so that radiation samples are always centered in the “Sample holder/clamp” over the radiation detector probe. Two stepper motors move along rods, lifting or lowering the sample holder to the desired position over the radiation detection probe. There is also an optional shielding component for the limitation of radiation emission that improves on the shelving method from previous devices. This is all supported with 3D printed rings and metal rods.https://scholarscompass.vcu.edu/capstone/1208/thumbnail.jp

Using the Depth of Knowledge Model to Create High School Mathematics Assessments--RESEARCH

This study examined the midterm exams of six high school math teachers and sought to (a) determine if teachers could accurately identify which level of Norman Webb’s Depth of Knowledge (DOK) model their test items aligned to, and (b) compare the actual percentage of test items at each DOK level to the targeted percentage based off Webb’s research. The study revealed that teachers were not accurate with their alignment of test items with Webb’s DOK model. They also came up short in comparison to the targeted percentages of test items at each level. Comprehensively, they were asking more questions at Level 1 and 2 instead of at Level 3 or 4. Recommendations are provided on how teachers can write questions at the targeted level for their course. Advancing high school students’ depth of knowledge (DOK) in mathematics can be challenging, so it is important for assessments to meet the appropriate levels of DOK. Finally, assessing the DOK levels of created test items is a task that can be difficult for most high school teachers. These challenges were the backdrop of this study

Paper Session I-B - Characterizing Space-Grown Degenerate Narrow Gap Semiconductors by Scanning Tunneling Optical Spectroscopy

We consider the II-VI narrow gap semiconducting alloys Hg(1-x)Cd(x)Te, Hg(1-x)Zn(x)Te, Hg(1-x)Zn(x)Se, for which empirical equations exist that give each alloy’s forbidden energy band gap Eg(x) as a function of its stoichiometry as characterized by the value x . These materials are important to NASA for two reasons. They are useful for making infrared detectors, and they are best grown in microgravity to optimize their uniformity. The equations can be inverted to yield the stoichiometry parameter x provided that the value of Eg can be determined experimentally, for example, by optical absorption measurements. We have investigated an alternative method, which should yield appreciably better spatial resolution, in which scanning tunneling optical spectroscopy (STOS) is used to measure the enhancement of the current that is due to photoexcitation of carriers at the tunneling junction in an STM. We present a simplified working model for low temperature calculations of STOS. Our major conclusions are: (a) for the degenerate case, knowledge of ND - NA (donor density minus the acceptor density) can be used to deduce the true band gap from the apparent band gap, (b) the low temperature tunneling current may have a sharper onset, depending on the diffusion length, at the band gap than does the optical absorption, and (c) our simplified formulation allows for quick, straightforward evaluation of many different cases and is in essential agreement with more detailed analysis

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https://openspace.dmacc.edu/banner_news/1440/thumbnail.jp

Feasibility and safety of the airway bypass procedure for patients with emphysema

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Effect of Alzheimer Caregiving Stress and Age on Frailty Markers Interleukin-6, C-Reactive Protein, and D-Dimer

Background. Elevated plasma levels of interleukin (IL)-6, C-reactive protein (CRP), and D-dimer belong to the biological alterations of the "frailty syndrome,” defining increased vulnerability for diseases and mortality with aging. We hypothesized that, compatible with premature frailty, chronic stress and age are related in predicting inflammation and coagulation activity in Alzheimer caregivers. Methods. Plasma IL-6, CRP, and D-dimer levels were measured in 170 individuals (mean age 73 ± 9 years; 116 caregivers, 54 noncaregiving controls). Demographic factors, diseases, drugs, and lifestyle variables potentially affecting inflammation and coagulation were obtained by history and adjusted for as covariates in statistical analyses. Results. Caregivers had higher mean levels of IL-6 (1.38 ± 1.42 vs 1.00 ± 0.92 pg/mL, p =.032) and of D-dimer (723 ± 530 vs 471 ± 211 ng/mL, p <.001) than controls had. CRP levels were similar between groups (p =.44). The relationship between caregiver status and D-dimer was independent of covariates (p =.037) but affected by role overload. Age accounted for much of the relationship with IL-6. After controlling for covariates, the interaction between caregiver status and age was significant for D-dimer (β =.20, p =.029) and of borderline significance for IL-6 (β =.17, p =.090). Post hoc regression analyses indicated that, among caregivers, age was significantly correlated with both D-dimer (β =.50, p <.001) and IL-6 (β =.38, p =.001). Among controls, however, no significant relationship was observed between age and either D-dimer or IL-6. Conclusions. The interaction between caregiving status and age for D-dimer and IL-6 suggests the possibility that older caregivers could be at risk of a more rapid transition to the frailty syndrome and clinical manifestations of cardiovascular disease

Effect of development of antibodies to hla and cytomegalovirus mismatch on lung transplantation survival and development of bronchiolitis obliterans syndrome

AbstractObjective: A retrospective analysis was performed to examine the role of HLA antibodies and cytomegalovirus mismatch on the development of bronchiolitis obliterans syndrome and survival after lung transplantation. Methods: Of 339 consecutive lung transplantations performed over a 102-month interval, 301 patients survived at least 3 months. There was a minimum follow-up period of 13 months. Bronchiolitis obliterans syndrome was defined as a decline in forced expiratory volume in 1 second less than 80% of posttransplantation baseline and/or histologic presence of obliterative bronchiolitis and was defined as occurring “early” if documented within 3 years of transplantation. Variables analyzed included preoperative donor and recipient cytomegalovirus status and the development of antibodies to human leukocyte antigens after transplantation. Microcytotoxicity was used to determine the presence of antibodies to human leukocyte antigens. Variables were subjected to Kaplan-Meier analysis to determine their impact on freedom from bronchiolitis obliterans syndrome and survival. Results: The development of antibodies to human leukocyte antigens after transplantation correlated significantly with bronchiolitis obliterans syndrome (P = .02). The development of antibodies to human leukocyte antigens did not affect survival (P = .33) unless they were detected within 2 years of transplantation (P = .04). There was greater frequency of early bronchiolitis obliterans syndrome in cytomegalovirus seronegative patients who received allografts from seropositive donors compared with all other combinations (P = .02). There was also a trend toward worse survival of cytomegalovirus seronegative patients who received allografts from seropositive donors (P = .13). Conclusion: These data suggest that bronchiolitis obliterans syndrome is the result of an immune-mediated process in which HLA antibodies and cytomegalovirus may play a significant role. (J Thorac Cardiovasc Surg 1998;116:812-20

Inhibition of inducible nitric oxide synthase ameliorates rat lung allograft rejection

AbstractRecently, the inducible isoform of nitric oxide synthase has been shown to be an important immunomodulation molecule in allograft rejection. We have observed the production of nitric oxide during rejection and the effect of nitric oxide synthase inhibition on allograft rejection in a rat lung transplant model. Rat left lung allotransplants were performed in two strain combinations: brown Norway–to–F344 (major histocompatibility complex incompatible); and Lewis-to-F344 (minor loci incompatible) as severe and mild rejection models respectively. Syngeneic F344-to-F344 transplants were performed as a negative control. Nitric oxide production during rejection was determined by measuring the recipient's serum nitrite/nitrate levels as a stable end product of nitric oxide. The progression of rejection was evaluated radiographically and the grade of rejection was determined histologically. After operation, recipients of allotransplantation were randomly divided into two groups and received either aminoguanidine (200 mg/kg, intraperitoneal every 6 hours), a potent inducible nitric oxide synthase inhibitor, or normal saline treatment. The levels of serum nitrite and nitrate in recipients increased in the early phase of rejection in both allotransplant combinations. However, in the terminal phase of rejection, the serum nitrite/nitrate level decreased significantly compared with the peak level in the brown Norway–to–F344 recipients. The serum nitrite/nitrate levels in the syngeneic transplant recipients were normal during the entire observation period. In aminoguanidine-treated animals, serum nitrite/nitrate levels remained normal in both allograft combinations. Significant suppression of rejection in aminoguanidine-treated recipients was observed histologically and radiographically in comparison with untreated recipients in the brown Norway–to–F344 combination. In the Lewis-to-F344 combination, aminoguanidine treatment significantly ameliorated histologic rejection but did not affect radiologic appearance. We therefore conclude nitric oxide is produced during early allograft rejection and may prove to be a marker and mediator of early rejection. The inhibition of inducible nitric oxide synthase results in significant reduction in rat lung allograft rejection. (J THORAC CARDIOVASC SURG 1995;110:1449-60