Donaldson-Thomas invariants and wall-crossing formulas

Notes from the report at the Fields institute in Toronto. We introduce the Donaldson-Thomas invariants and describe the wall-crossing formulas for numerical Donaldson-Thomas invariants.Comment: 18 pages. To appear in the Fields Institute Monograph Serie

Adolescent Boys are at Risk for Body Image Dissatisfaction and Muscle Dysmorphia

Background and Purpose: Muscle Dysmorphia (MD) is characterized by extreme body dissatisfaction and a drive for muscularity that leads to compulsive behaviors to attain an ideal body shape. The primary purpose of this study was to assess the level of body image dissatisfaction (BID) among male adolescents (N = 149, mean age = 15.01 + 1.85 y and mean BMI = 23.26 + 5.01 kg/m2 ) and whether or not BID was correlated with behaviors associated with MD. A secondary purpose was to examine if a difference exists between athletes and non-athletes. Methods: The Eating Attitude Survey (EAS) was used to assess attitudes toward body weight and shape while the Muscle Dysmorphia Inventory (MDI) was used to assess the behavioral and psychological characteristics of MD. Results: This sample of male adolescents indicate some level of BID, which is also associated with overall higher scores for all subscales of the MDI, but especially the subscales relating to muscularity. Athletes in particular showed higher levels of BID and higher scores on the MDI. Conclusion: Individuals who work with adolescent boys should be aware that they can develop body dissatisfaction and may participate in compensatory behaviors that may be harmful to their overall health and development

Degenerate flag varieties: moment graphs and Schr\"oder numbers

We study geometric and combinatorial properties of the degenerate flag varieties of type A. These varieties are acted upon by the automorphism group of a certain representation of a type A quiver, containing a maximal torus T. Using the group action, we describe the moment graphs, encoding the zero- and one-dimensional T-orbits. We also study the smooth and singular loci of the degenerate flag varieties. We show that the Euler characteristic of the smooth locus is equal to the large Schr\"oder number and the Poincar\'e polynomial is given by a natural statistics counting the number of diagonal steps in a Schr\"oder path. As an application we obtain a new combinatorial description of the large and small Schr\"oder numbers and their q-analogues.Comment: 25 page

Linear degenerations of flag varieties: partial flags, defining equations, and group actions

We continue, generalize and expand our study of linear degenerations of flag varieties from Cerulli Irelli et al. (Math Z 287(1–2):615–654, 2017). We realize partial flag varieties as quiver Grassmannians for equi-oriented type A quivers and construct linear degenerations by varying the corresponding quiver representation. We prove that there exists the deepest flat degeneration and the deepest flat irreducible degeneration: the former is the partial analogue of the mf-degenerate flag variety and the latter coincides with the partial PBW-degenerate flag variety. We compute the generating function of the number of orbits in the flat irreducible locus and study the natural family of line bundles on the degenerations from the flat irreducible locus. We also describe explicitly the reduced scheme structure on these degenerations and conjecture that similar results hold for the whole flat locus. Finally, we prove an analogue of the Borel–Weil theorem for the flat irreducible locus

Renal phenotype of Et-1 transgenic mice is modulated by androgens

<p>Abstract</p> <p>Introduction</p> <p>Activation of the endothelin (ET) system promotes inflammation and fibrosis in various tissues including the kidney. Male ET-1 transgenic mice are characterized by chronic kidney inflammation and renal scarring. We hypothesized that this renal phenotype might be modulated by androgens. Thus the aim of our study was to elucidate the impact of gonadectomy in ET-1 transgenic mice on kidney function and morphology.</p> <p>Methods</p> <p>Male ET-1 transgenic mice at the age of 10 weeks were randomly allocated to the following groups: normal ET transgenic mice (ET; n = 17) and ET transgenic mice that underwent castration (ET+cas; n = 12). Study duration was 9 months. Creatinine clearance and protein excretion was monitored. At study end animals were sacrificed and kidneys were harvested for histology/immunhistochemistry.</p> <p>Results</p> <p>Castration significantly ameliorated glomerulosclerosis in ET-1 transgenic mice (ET glomerulosclerosis-score: 3.0 ± 0.17 vs ET+cas: 2.4 ± 0.17; p < 0.05) as well as renal perivascular fibrosis (ET fibrosis-score: 3.0 ± 0.14 vs ET+cas: 2.2 ± 0.14; p < 0.05). However, interstitial fibrosis and media/lumenratio of renal arteries remained unaffected by castration. Regarding inflammation, castration significantly reduced the number of CD4-positive cells in renal tissue of ET-1 transgenic mice (ET CD4-positive cells/10000 cells: 355 ± 72 vs ET+cas: 147 ± 28; p < 0.05). Renal tissue contents of CD8 positive cells as well as of macrophages were not affected by castration. Regarding kidney function castration significantly reduced proteinuria in ET-1 transgenic mice whereas creatinine clearance did not differ between study groups.</p> <p>Conclusion</p> <p>Our study demonstrates that the renal histopathological phenotype in male ET-1 transgenic mice with regard to glomerulosclerosis, proteinuria, perivascular fibrosis and immune cell immigration is ameliorated by castration. We thus conclude that the effects of ET-1 overexpression on renal tissue injury are modulated by androgens.</p

Stability conditions and Stokes factors

Let A be the category of modules over a complex, finite-dimensional algebra. We show that the space of stability conditions on A parametrises an isomonodromic family of irregular connections on P^1 with values in the Hall algebra of A. The residues of these connections are given by the holomorphic generating function for counting invariants in A constructed by D. Joyce.Comment: Very minor changes. Final version. To appear in Inventione

Market access to new anticancer medicines for children and adolescents with cancer in Europe

BACKGROUND AND AIMS: There is an alarming delay in Europe for anticancer medicines becoming accessible for children. Following a paediatric European Union marketing authorisation, national Health Technology Assessment (HTA) agencies evaluate effectiveness, and safety of medicines to support decision on their cost and reimbursement. This study (a SIOPE Access to Medicines project) aimed to evaluate how these HTA evaluations take place for anticancer medicines indicated for paediatric use in Europe and to explore where the delays for market access originate. METHODS: We obtained HTA reports from the public domain for nine European countries for blinatumomab, dinutuximab beta and tisagenlecleucel. We evaluated the time elapsed between marketing authorisation for a paediatric indication and a national HTA decision and the nature of the decision. RESULTS: Out of 23 HTA decisions (four countries without blinatumomab report), 18 were positive, two with restrictions, three negative. For blinatumomab, tisagenlecleucel and dinutuximab beta, the median time to an HTA decision after regulatory approval for paediatric use was 353 days (range 193-751), 141 days (range 77-517) and 515 days (range 0-780), respectively, with variability between countries. Dinutuximab beta and tisagenlecleucel were first introduced in children, but did not result in shorter time to HTA decision. For blinatumomab, marketing authorisation followed 1008 days after the indication in adults, with HTA applications submitted a median of 167 days later, and a recommendation after 145 days. CONCLUSIONS: This study reveals ample variability in HTA decision making in nine European Union countries. Collaboration and alignment of required evidence is needed to facilitate robust scientific HTA assessments, also considering methodological challenges in paediatric oncology

Spatting restricts ankle motion more effectively than taping during exercise

Ankle injuries, via plantarflexion (PF) and inversion, are commonplace today. To reduce ankle injuries, restrictive appliances such as taping and bracing have been employed. These appliances, however, have the disadvantage of potentially loosening considerably with mild activity. Spatting—applying tape over the shoe and sock—has been suggested as a viable alternative, yet its efficacy has not been researched widely. We examined the effects of taping or spatting the ankles on 17 men (age = 20.7 ± 2.1 years; height = 185.7 ± 5.7 cm; mass = 93.6 ± 16.2 kg) before, during, and after 60 minutes of exercise involving multi-directional activity. Active range of motion (ROM) for PF and inversion was measured via goniometry for each subject\u27s dominant leg to establish baseline values. ROM was measured after the appliances were applied, then following a five-minute warm-up period, and after each of three, 20-minute exercise periods. The subjects also completed a 5-item, 5-point Likert-type scale survey regarding their perceptions of each ankle appliance with respect to comfort, effectiveness, and protective ability. Separate, two-way ANOVAs with repeated measures were used to assess differences in PF and inversion ROM relative to time. A series of Wilcoxon tests were used to assess the Likert-type scale survey. In comparison to spatting, taping loosened by ~5° for PF at 40 minutes and by ~3° for inversion at 20 minutes (both significant interactions, p \u3c 0.01). Thus indicating that spatting is more restrictive than taping after 20 minutes of exercise. Interestingly, taping was perceived as more comfortable than spatting (Z = 2.03, p = 0.04); nonetheless, the perceived protection along with the perceived ability to move before, during, and after exercise was rated similarly between the appliances (p \u3e 0.05). Despite an advantage of restricting PF and inversion during exercise with spatting, it is not known if the loss of tape-skin contact underscores the potential benefits associated with the neuromuscular reactivity that have been reported with taping. Additional research is needed to clarify this issue