Blocks and support varieties

The theory of support varieties gives a rich supply of examples of thick subcategories of the stable module category of a finite group algebra. We study direct sum decompositions of such categories. We give examples where there are finer decompositions than one might originally expect, and relate this to Linckelmann's theory of block varieties

CTC-ask: a new algorithm for conversion of CT numbers to tissue parameters for Monte Carlo dose calculations applying DICOM RS knowledge

One of the building blocks in Monte Carlo (MC) treatment planning is to convert patient CT data to MC compatible phantoms, consisting of density and media matrices. The resulting dose distribution is highly influenced by the accuracy of the conversion. Two major contributing factors are precise conversion of CT number to density and proper differentiation between air and lung. Existing tools do not address this issue specifically. Moreover, their density conversion may depend on the number of media used. Differentiation between air and lung is an important task in MC treatment planning and misassignment may lead to local dose errors on the order of 10%. A novel algorithm, CTC-ask, is presented in this study. It enables locally confined constraints for the media assignment and is independent of the number of media used for the conversion of CT number to density. MC compatible phantoms were generated for two clinical cases using a CT-conversion scheme implemented in both CTC-ask and the DICOM-RT toolbox. Full MC dose calculation was subsequently conducted and the resulting dose distributions were compared. The DICOM-RT toolbox inaccurately assigned lung in 9.9% and 12.2% of the voxels located outside of the lungs for the two cases studied, respectively. This was completely avoided by CTC-ask. CTC-ask is able to reduce anatomically irrational media assignment. The CTC-ask source code can be made available upon request to the authors

Subsidies in Oligopoly Markets: A Welfare Comparison Between Symmetric and Asymmetric Costs

Oligopolistic industries generally produce less than is socially desirable. As a result, the use of production subsidies is often suggested as a means of raising production toward the efficient level in imperfectly competitive markets. In cases where firms are equally efficient in producing the good, the common prescription is a policy of uniform subsidization, as suggested by Besley (1989).(1) When firms in an industry differ in cost efficiency, however, uniform subsidization involves subsidizing inefficient firms in the same manner as efficient firms. Consequently, uniform policy may be undesirable from a social perspective, particularly when the price-cost margins of inefficient firms are small. In an oligopolistic industry comprising firms that differ in cost effectiveness, one might ideally like to subsidize only the most efficient firm(s) and perhaps tax or even exclude inefficient firms from the market. Yet, in many situations, treating rival firms in an industry differently is politically infeasible. It is therefore important to understand how the welfare implications of uniform policy in an asymmetric-cost industry diverge from the case of equal cost efficiency. Different welfare implications are likely to arise because changes in regulatory structure can affect market structure in an asymmetric-cost industry (see Dierickx, Matutes, and Neven 1988; Kimmel 1992). Several papers in the public finance literature have addressed the issue of tax incidence on the rivalry and profitability of firms in oligopoly markets. Katz and Rosen (1985) show, in a conjectural variations model with symmetric firms, that a uniform tax on production can lead to an outcome with larger after-tax profits for firms. This result is also supported by Dierickx, Matutes, and Neven (1988); Kimmel (1992); and Seade (1985) for the case when the cost efficiency of firms differs. However, these papers do not directly analyze the industry profit and social welfare effects of a change in the tax or subsidy program. This article identifies relevant implications for tax policy by comparing welfare changes in the asymmetric-cost case to a benchmark case of symmetric costs. It is shown that, relative to the symmetric-cost case, the welfare effect is smaller when demand is nonconvex in the asymmetric-cost case, while the opposite is true for the case of convex demand. The greater the cost asymmetry in the industry and the more collusive firm behavior, the greater is this difference in welfare impact

Utilizing the American Board of Surgery in-training exam in a Rwandan surgical residency program: Alignment of exam topics with the University of Rwanda general surgery curriculum

Background: University of Rwanda (UR) increased postgraduate surgery training and assessment strategies are needed. We compared American Board of Surgery In-Training Exam (ABSITE) topics with UR surgery curriculum to determine the applicability of ABSITE in Rwanda.Methods: Topics are outlined in the Surgical Council on Resident Education (SCORE) curriculum whereas the UR utilizes a modular system. Diseases and conditions in SCORE were compared with UR surgery module content. Operation and procedures in SCORE were compared with operative procedures in UR surgery curriculum.Results: Overall, 72% of diseases and conditions from SCORE were covered in UR curriculum. Of this, 76% of medical knowledge and 71% of patient care content was covered in UR curriculum. 41% of operations and procedures from SCORE were identified in UR curriculum. 55% of core operations and 16% of advanced operations from SCORE were included in UR general surgery curriculum. Content identified in UR curriculum and not SCORE included infectious and tropical diseases, orthopedics, urology and neurosurgery.Conclusions: There is alignment between ABSITE topics and UR general surgery curriculum suggesting that the ABSITE can be used as an in-training examination for Rwandan residents. Understanding the limitations of the ABSITE exam can help utilization of this examination.Keywords: internship and residency, curriculum, Rwanda, global healt

Lack of involvement of lipocortin 1 in dexamethasone suppression of IL-1 release

The annexin lipocortin 1 is reported to mediate some anti-inflammatory effects of glucocorticoids, but the mechanisms of this mediation are incompletely understood. The involvement of lipocortin 1 in glucocorticoid inhibition of monocyte interleukin 1β (IL-1β) release has been investigated. Treatment of peripheral blood monocytes with 2 μg/ml lipopolysaccharide potently increased IL–1β release (p = 0.001) and dexamethasone (10−7 M) significantly reduced both resting and stimulated IL-1β release (p = 0.009). A neutralizing monoclonal antibody to lipocortin 1 (0.5–50.0 μg/ml) was unable to inhibit this effect and recombinant lipocortin 1 (2 × 10−6 M) and 188aa lipocortin 1 fragment (10−8−10−6 M) had no effect. It is concluded that lipocortin 1 is not involved in the inhibition of monocyte IL-1β release by glucocorticoids

Atomic Scale Depth Profile of Space Weathering in an Itokawa Olivine Grain

No abstract available

Ozonolysis of a-phellandrene - Part 2 : Compositional analysis of secondary organic aerosol highlights the role of stabilized Criegee intermediates

The molecular composition of secondary organic aerosol (SOA) generated from the ozonolysis of α-phellandrene is investigated for the first time using high pressure liquid chromatography coupled to high-resolution Quadrupole-Orbitrap tandem mass spectrometry. In total, 21 prominent products or isomeric product groups were identified using both positive and negative ionisation modes, with potential formation mechanisms discussed. The aerosol was found to be composed primarily of polyfunctional first- and second-generation species containing one or more carbonyl, acid, alcohol and hydroperoxide functionalities, with the products significantly more complex than those proposed from basic gas-phase chemistry in the companion paper (Mackenzie-Rae et al., 2017a). Mass spectra show a large number of dimeric products are also formed. Both direct scavenging evidence using formic acid, and indirect evidence from double bond equivalency factors, suggests the dominant oligomerisation mechanism is the bimolecular reaction of stabilised Criegee intermediates (SCIs) with non-radical ozonolysis products. Saturation vapour concentration estimates suggest monomeric species cannot explain the rapid nucleation burst of fresh aerosol observed in chamber experiments, hence dimeric species are believed to be responsible for new particle formation, with detected first- and second-generation products driving further particle growth in the system. Ultimately, identification of the major constituents and formation pathways of α-phellandrene SOA leads to a greater understanding of the atmospheric processes and implications of monoterpene emissions and SCIs, especially around Eucalypt forests regions where α-phellandrene is primarily emitted

[CI] and CO in the center of M 51

We present J=2-1, J=3-2, J=4-3 12CO maps as well as J=2-1, J=3-2 13CO and 492 GHz [CI] measurements of the central region in M51. The distribution of CO is strongly concentrated towards the spiral arms. The center itself is poor in, though not devoid of, CO emission. The observed line intensities require modelling with a multi-component molecular gas. A dense component must be present with n(H2) = 1000 cm-3 and kinetic temperature T(kin)= 100 K, combined with either a less dense (about 100 cm-3) component of the same temperature, or a more dense (n(H2) = 3000 cm-3) and much cooler (T(kin) = 10-30 K) component. Atomic carbon amounts are between 5 and 10 times those of CO. Much of the molecular gas mass is associated with the hot PDR phase. The center of M 51 has a face-on gas mass density of about 40+/-20 M(O) pc-2, and a well-established CO-to-H2 conversion ratio X four to five times lower than the standard Galactic value.Comment: Accepted for publication by A&