Ices in the edge-on disk CRBR 2422.8-3423: Spitzer spectroscopy and Monte Carlo radiative transfer modeling

We present 5.2-37.2 micron spectroscopy of the edge-on circumstellar disk CRBR 2422.8-3423 obtained using the InfraRed Spectrograph (IRS) of the Spitzer Space Telescope. The IRS spectrum is combined with ground-based 3-5 micron spectroscopy to obtain a complete inventory of solid state material present along the line of sight toward the source. We model the object with a 2D axisymmetric (effectively 3D) Monte Carlo radiative transfer code. It is found that the model disk, assuming a standard flaring structure, is too warm to contain the very large observed column density of pure CO ice, but is possibly responsible for up to 50% of the water, CO2 and minor ice species. In particular the 6.85 micron band, tentatively due to NH4+, exhibits a prominent red wing, indicating a significant contribution from warm ice in the disk. It is argued that the pure CO ice is located in the dense core Oph-F in front of the source seen in the submillimeter imaging, with the CO gas in the core highly depleted. The model is used to predict which circumstances are most favourable for direct observations of ices in edge-on circumstellar disks. Ice bands will in general be deepest for inclinations similar to the disk opening angle, i.e. ~70 degrees. Due to the high optical depths of typical disk mid-planes, ice absorption bands will often probe warmer ice located in the upper layers of nearly edge-on disks. The ratios between different ice bands are found to vary by up to an order of magnitude depending on disk inclination due to radiative transfer effects caused by the 2D structure of the disk. Ratios between ice bands of the same species can therefore be used to constrain the location of the ices in a circumstellar disk. [Abstract abridged]Comment: 49 pages, accepted for publication in Ap

Systematic review for non-surgical interventions for the management of late radiation proctitis

Chronic radiation proctitis produces a range of clinical symptoms for which there is currently no recommended standard management. The aim of this review was to identify the various non-surgical treatment options for the management of late chronic radiation proctitis and evaluate the evidence for their efficacy. Synonyms for radiation therapy and for the spectrum of lower gastrointestinal radiation toxicity were combined in an extensive search strategy and applied to a range of databases. The included studies were those that involved interventions for the non-surgical management of late radiation proctitis. Sixty-three studies were identified that met the inclusion criteria, including six randomised controlled trials that described the effects of anti-inflammatory agents in combination, rectal steroids alone, rectal sucralfate, short chain fatty acid enemas and different types of thermal therapy. However, these studies could not be compared. If the management of late radiation proctitis is to become evidence based, then, in view of its episodic and variable nature, placebo controlled studies need to be conducted to clarify which therapeutic options should be recommended. From the current data, although certain interventions look promising and may be effective, one small or modest sized study, even if well-conducted, is insufficient to implement changes in practice. In order to increase recruitment to trials, a national register of cases with established late radiation toxicity would facilitate multi-centre trials with specific entry criteria, formal baseline and therapeutic assessments providing standardised outcome data

The Impact of Peer Collaboration in Enhancing Mathematics Teachers’ Pedagogical Content Knowledge and Skills : Lessons from Tanzania

タンザニア政府の数学教員の教授学的知識と技術を向上させるための現職教員研修は大きな課題を抱えているとされている．今回確率分野を事例としてO レベル数学教員６名と１２学年生徒１３０名を対象に，観察，聞き取り調査および学生に対するテストを行い，数学教員支援恊働（COSMAT）プログラムの評価を行った．その結果，数学教員はプログラムを通じ，恊働するようになり，教授学的知識と技術を向上させている．また活動中心の確率の授業を受講することで学生の成績も前後で向上している．従ってプログラムが正の影響を与えていることがわかった．It is reported that the Tanzania government is facing a big challenge of organising in-service education programmes that would have impact on mathematics teachers’ pedagogical content knowledge and skills (PCK&S), which ultimately improve students’ performance in the subject. By using development research approach, a study was designed to evaluate the impact of peer collaboration with the use exemplary materials in probability. The investigation involved 6 ordinary level (junior secondary) mathematics teachers and 130 Form 4 (12th Graders) mathematics students. In data collection, the study used triangulation process that involved observation of collaborative activities, interviews, and student test. Findings from this study revealed that teachers had adopted the collaborative activities that were promoted through the programme for the purpose of enhancing their PCK&S. Moreover, they were also stimulated to conduct other collaborative activities. Findings from students’ test results showed that there was a significant difference between pre-test and post-test scores, demonstrating that students gained knowledge as a result of activity-based probability lessons. Combining the results from teachers’ experiences with peer collaboration and students’ learning, it can be concluded that the COllaboration to Support MAthematics Teachers (COSMAT) programme had yielded a positive impact on teachers’ PCK&S and teacher collaboration