Superimposition of beams to vary shot size in gamma knife stereotactic radiosurgery

The Leksell Gamma Knife [Elekta Corp] uses helmets as collimators to produce four standard beam sizes. The nominal beam diameters are 18, 14, 8, and 4 mm. During computer treatment planning for gamma knife stereotactic radiosurgery, the size of the treated volume may differ from the standard beam sizes. To maintain conformality of the isodose curves to the treated volume, beam sizes may be superimposed during computer treatment planning to produce beam diameters that are intermediate to the standard beams. A study of superimposed gamma knife beams was performed to confirm the accuracy of this method and to verify the accuracy of the GammaPlan treatment planning computer. Superimposed beams were simulated on the Elekta treatment planning computer, GammaPlan, version 4.12, and tested by film measurements of beam profiles for single helmet sizes and superimposed shots with various beam weightings. The weighting for each beam size is varied to attain the beam size diameter desired. The beams were defined at the 50% isodose line. The profiles of the superimposed beams were obtained and compared with the single helmet shots. The uniformity of the resulting beams was measured. The results show a linear relationship between beam size and beam weighting for the superimposed beams. The film measurements confirm the computer calculations

Intraduodenal sarcoma recurrence of retroperitoneal origin: an unusual cause for a duodenal obstruction.

Soft tissue sarcomas are uncommon tumors, and intraduodenal soft tissue sarcoma manifestation is even more rare. Only three cases of intraduodenal sarcomas have been reported in the literature thus far. Here, we report a case of an intraduodenal recurrence of a retroperitoneal sarcoma causing bowel obstruction. This unusual recurrence pattern likely relates to the patient's previous resection and radiation treatment, and highlights the benefits, limitations and follow-up strategies after multimodality treatment

Values in the backyard:The relationship between people’s values and their evaluations of a real, nearby energy project

Research on abstract and/or hypothetical energy projects (e.g., nuclear, wind, solar energy) has shown that people favour energy projects that support their core values, and disfavour energy projects that threaten their core values. The question is to what extent people consider the implications for their values once energy projects become concrete, have real consequences, and come to their backyard. In a community affected by earthquakes induced by gas extraction, we studied the relationships between people’s values and their concerns about the earthquakes and acceptability of the gas extraction. The more strongly people endorsed biospheric values (i.e., caring about nature and the environment) and altruistic values (i.e., caring about others), the more negatively they evaluated gas extraction and the induced earthquakes. Stronger egoistic values (i.e., caring about personal resources) were associated with less negative evaluations of gas extraction and the earthquakes, possibly due to user and economic benefits associated with energy supply from natural gas. The findings were consistent across three local regions that vary in exposure to earthquakes and across five measurement points over six years, providing robust evidence that people consider the implications for their values when evaluating real, nearby energy projects. Furthermore, the results substantiate the critique of the NIMBY (Not-in-My-Backyard) explanation of local resistance to energy projects, which assumes that people are guided exclusively by immediate selfish concerns

Development of a ‘Universal’ Rubric for Assessing Undergraduates’ Scientific Reasoning Skills Using Scientific Writing

We developed a rubric for measuring students’ ability to reason and write scientifically. The Rubric for Science Writing (Rubric) was tested in a variety of undergraduate biology laboratory courses (total n = 142 laboratory reports) using science graduate students (teaching assistants) as raters. Generalisability analysis indicates that the Rubric provides a reliable measure of students’ abilities (g = 0.85) in these conditions. Comparison of student performance in various biology classes indicated that some scientific skills are more challenging for students to develop than others and identified a number of previously unappreciated gaps in the curriculum. Our findings suggest that use of the Rubric provides three major benefits in higher education: (1) to increase substance and consistency of grading within a course, particularly those staffed by multiple instructors or graduate teaching assistants; (2) to assess student achievement of scientific reasoning and writing skills; and (3) when used in multiple courses, to highlight gaps in alignment among course assignments and provide a common metric for assessing to what extent the curriculum is achieving programmatic goals. Lastly, biology graduate students reported that use of the Rubric facilitated their teaching and recommended that training on the Rubric be provided to all teaching assistants

Identification of β2-adrenoceptors on guinea pig alveolar macrophages using (-)-3-[125I]iodocyanopindolol

The β-adrenoceptor antagonist (-)-3-[125I]iodocyanopindolol ([125I]ICYP) binds with high affinity and in a saturable way to membranes of guinea pig alveolar macrophages. The equilibrium dissociation constant for [125I]ICYP is 24.3 ± 1.2 pM, and the number of binding sites is 166.3 ± 13.7 fmol/mg protein (N=4, ±SEM). Displacement studies with selective antagonists showed that [125I]ICYP labels β2-adrenoceptors on guinea pig alveolar macrophages

What\u27s New in Plant Pathology: Resistance: Mystery and Misunderstandings

One of the most common management recommendations for plant diseases is the use of resistant or tolerant varieties/hybrids in your production system. However, there is common confusion on the definition and differentiation of susceptible, tolerant, and resistant varieties/hybrids from a plant pathology viewpoint. A susceptible variety/hybrid allows the pathogen to reproduce and causes significant disease development and in turn compromises the productivity of the plant (i.e., yield). A tolerant variety/hybrid allows the pathogen to reproduce and cause disease at the same or at a slightly reduced rate as a susceptible variety/cultivar; however, there is no noticeable reduction in the plant’s overall productivity. Finally, a resistant variety/hybrid limits or prevents pathogen reproduction and disease development; hence, plant productivity is little or not affected while the plant remains very productive. It is important to note that plant resistance is not plant “immunity,” where it is expected that a variety/hybrid will have NO disease. Unfortunately, immunity does not exist for the majority of plant diseases and expecting such a reaction (or lack thereof) is unrealistic. Resistance, simply, is a reduction in disease severity due to the plant’s defenses. Plants have many mechanisms for defense but do not possess immune systems comparable to our own that preclude infection and disease development