Supersymmetric Schur functions and Lie superalgebra representations

Lie superalgebras and their representations continue to play an important role in the understanding and exploitation of supersymmetry in physical systems. The Lie superalgebras that we consider, namely gl(m|n) and sl(m|n) (sometimes denoted as U(m|n) and SU(m|n)), have applications in quantum mechanics, nuclear physics, string theory, conformal field theory, supergravity, M-theory, lattice QCD, solvable lattice models, spin systems and quantum systems. The representation theory of Lie superalgebras and in particular of gl(m|n) or its simple counterpart sl(m|n), is not a straightforward copy of the corresponding theory of Lie algebras. In the early days of Lie superalgebra representation theory, it was believed that the standard methods of covariant, contravariant and mixed tensor representations with the corresponding Young techniques yield the characters of gl(m|n) irreducible representations in terms of supersymmetric S-functions. Although this is certainly true for the covariant and contravariant tensor representations2, where the supersymmetric S-function is labelled by a single partition λ, it is not so for the mixed tensor representations3 where the corresponding S-function is labelled by a composite partition ¯ν ;μ. In our research we have first concentrated on supersymmetric S-functions labelled by a partition, for which a determinantal formula was constructed4 using a technique of Kac-Wakimoto. Once this determinantal formula for sλ(x/y) was found, we realized that its validity could also be proved in different ways4, for example using the characterization given by Macdonald5. Furthermore, our work led to new dimension and superdimension formulas6. Following this, we showed that there is still another family of typical representations for which the character is given by a (composite) S-function, namely the so-called critical gl(m|n) representations7. It is conjectured that, under certain conditions, the character indeed coincides with a supersymmetric Schur function indexed by a composite partition. Again, this work gives rise to new dimension and superdimension formulas

Improving the translation environment for professional translators

When using computer-aided translation systems in a typical, professional translation workflow, there are several stages at which there is room for improvement. The SCATE (Smart Computer-Aided Translation Environment) project investigated several of these aspects, both from a human-computer interaction point of view, as well as from a purely technological side. This paper describes the SCATE research with respect to improved fuzzy matching, parallel treebanks, the integration of translation memories with machine translation, quality estimation, terminology extraction from comparable texts, the use of speech recognition in the translation process, and human computer interaction and interface design for the professional translation environment. For each of these topics, we describe the experiments we performed and the conclusions drawn, providing an overview of the highlights of the entire SCATE project

Recurrence risk of venous thromboembolism associated with systemic lupus erythematosus:A retrospective cohort study

BACKGROUND: Recurrence risk of systemic lupus erythematosus (SLE)‐associated venous thromboembolism (VTE) is unclear. AIM: To determine the recurrence risk of SLE‐associated VTE overall and by presence of provoking factors and SLE flares. METHODS: A multicenter, retrospective cohort study was conducted among patients with first SLE‐associated VTE who discontinued anticoagulation. SLE flares were defined as Systemic Lupus Erythematosus Disease Activity Index 2000 greater than 4. The primary outcome was recurrent VTE. Incidence rates and cumulative incidences were calculated by presence of provoking factors and antiphospholipid syndrome (APS) at index VTE. The hazard ratio (HR) for recurrence after SLE flare–associated index VTE was estimated with Cox regression, adjusted for provoking factor presence and APS. RESULTS: Eighty patients were included with 21 recurrent VTEs in median 8 years. For provoked index VTE, the recurrence rate in patients without APS was 1.1 per 100 person‐years (PY; 95% confidence interval [CI], 0.1–3.1) and in the presence of APS 3.5 per 100 PY (95% CI, 0.9–8.9), yielding cumulative incidences of 7.5% (95% CI, 1.2%–21.7%) and 31.4% (95% CI, 6.3%–61.6%) respectively. For unprovoked index VTE, these analogous rates were 3.8 per 100 PY (95% CI, 1.2–9.0) and 16.7 per 100 PY (95% CI, 4.5–42.7), with cumulative incidences of 33.7% (95% CI, 10.7%–58.9%) and 54.2% (95% CI, 10.7%–84.5%), respectively. Forty‐six index VTEs were flare associated, and the adjusted HR for recurrence was 0.4 (95% CI, 0.1–1.8) compared to those without flares at their index VTE. CONCLUSION: Antiphospholipid syndrome is the main determinant for recurrence risk of SLE‐associated VTE irrespective of presence of a provoking factor. Future research should attempt to confirm that flare‐associated VTE has a lower recurrence risk

Smart Computer-Aided Translation Environment (SCATE): Highlights

We present the highlights of the now finished 4-year SCATE project. It was completed in February 2018 and funded by the Flemish Government IWT-SBO, project No. 130041

Discovery of a New Human Polyomavirus Associated with Trichodysplasia Spinulosa in an Immunocompromized Patient

The Polyomaviridae constitute a family of small DNA viruses infecting a variety of hosts. In humans, polyomaviruses can cause infections of the central nervous system, urinary tract, skin, and possibly the respiratory tract. Here we report the identification of a new human polyomavirus in plucked facial spines of a heart transplant patient with trichodysplasia spinulosa, a rare skin disease exclusively seen in immunocompromized patients. The trichodysplasia spinulosa-associated polyomavirus (TSV) genome was amplified through rolling-circle amplification and consists of a 5232-nucleotide circular DNA organized similarly to known polyomaviruses. Two putative “early” (small and large T antigen) and three putative “late” (VP1, VP2, VP3) genes were identified. The TSV large T antigen contains several domains (e.g. J-domain) and motifs (e.g. HPDKGG, pRb family-binding, zinc finger) described for other polyomaviruses and potentially involved in cellular transformation. Phylogenetic analysis revealed a close relationship of TSV with the Bornean orangutan polyomavirus and, more distantly, the Merkel cell polyomavirus that is found integrated in Merkel cell carcinomas of the skin. The presence of TSV in the affected patient's skin was confirmed by newly designed quantitative TSV-specific PCR, indicative of a viral load of 105 copies per cell. After topical cidofovir treatment, the lesions largely resolved coinciding with a reduction in TSV load. PCR screening demonstrated a 4% prevalence of TSV in an unrelated group of immunosuppressed transplant recipients without apparent disease. In conclusion, a new human polyomavirus was discovered and identified as the possible cause of trichodysplasia spinulosa in immunocompromized patients. The presence of TSV also in clinically unaffected individuals suggests frequent virus transmission causing subclinical, probably latent infections. Further studies have to reveal the impact of TSV infection in relation to other populations and diseases