1,789 research outputs found
Canonical structure of the E10 model and supersymmetry
A coset model based on the hyperbolic Kac-Moody algebra E10 has been
conjectured to underly eleven-dimensional supergravity and M theory. In this
note we study the canonical structure of the bosonic model for finite- and
infinite-dimensional groups. In the case of finite-dimensional groups like
GL(n) we exhibit a convenient set of variables with Borel-type canonical
brackets. The generalisation to the Kac-Moody case requires a proper treatment
of the imaginary roots that remains elusive. As a second result, we show that
the supersymmetry constraint of D=11 supergravity can be rewritten in a
suggestive way using E10 algebra data. Combined with the canonical structure,
this rewriting explains the previously observed association of the canonical
constraints with null roots of E10. We also exhibit a basic incompatibility
between local supersymmetry and the K(E10) `R symmetry', that can be traced
back to the presence of imaginary roots and to the unfaithfulness of the spinor
representations occurring in the present formulation of the E10 worldline
model, and that may require a novel type of bosonisation/fermionisation for its
resolution. This appears to be a key challenge for future progress with E10.Comment: 1+39 pages. v2: small corrections. Version to appear in PR
Sugawara-type constraints in hyperbolic coset models
In the conjectured correspondence between supergravity and geodesic models on
infinite-dimensional hyperbolic coset spaces, and E10/K(E10) in particular, the
constraints play a central role. We present a Sugawara-type construction in
terms of the E10 Noether charges that extends these constraints infinitely into
the hyperbolic algebra, in contrast to the truncated expressions obtained in
arXiv:0709.2691 that involved only finitely many generators. Our extended
constraints are associated to an infinite set of roots which are all imaginary,
and in fact fill the closed past light-cone of the Lorentzian root lattice. The
construction makes crucial use of the E10 Weyl group and of the fact that the
E10 model contains both D=11 supergravity and D=10 IIB supergravity. Our
extended constraints appear to unite in a remarkable manner the different
canonical constraints of these two theories. This construction may also shed
new light on the issue of `open constraint algebras' in traditional canonical
approaches to gravity.Comment: 49 page
Use of clofarabine for acute childhood leukemia
A second-generation of purine nucleoside analogs, starting with clofarabine, has been developed in the course of the search for new therapeutic agents for acute childhood leukemia, especially for refractory or relapsed disease. Clofarabine is a hybrid of fludarabine and cladribine, and has shown to have antileukemic activity in acute lymphoblastic leukemia as well as in myeloid disorders. As the only new antileukemic chemotherapeutic agent to enter clinical use in the last 10 years, clofarabine was approved as an orphan drug with the primary indication of use in pediatric patients. Toxicity has been tolerable in a heavily pretreated patient population, and clofarabine has been demonstrated to be safe, both as a single agent and in combination therapies. Liver dysfunction has been the most frequently observed adverse event, but this is generally reversible. Numerous Phase I and II trials have recently been conducted, and are still ongoing in an effort to find the optimal role for clofarabine in various treatment strategies. Concomitant use of clofarabine, cytarabine, and etoposide was confirmed to be safe and effective in two independent trials. Based on the promising results when used as a salvage regimen, clofarabine is now being investigated for its potential to become part of frontline protocols
Use of clofarabine for acute childhood leukemia.
A second-generation of purine nucleoside analogs, starting with clofarabine, has been developed in the course of the search for new therapeutic agents for acute childhood leukemia, especially for refractory or relapsed disease. Clofarabine is a hybrid of fludarabine and cladribine, and has shown to have antileukemic activity in acute lymphoblastic leukemia as well as in myeloid disorders. As the only new antileukemic chemotherapeutic agent to enter clinical use in the last 10 years, clofarabine was approved as an orphan drug with the primary indication of use in pediatric patients. Toxicity has been tolerable in a heavily pretreated patient population, and clofarabine has been demonstrated to be safe, both as a single agent and in combination therapies. Liver dysfunction has been the most frequently observed adverse event, but this is generally reversible. Numerous Phase I and II trials have recently been conducted, and are still ongoing in an effort to find the optimal role for clofarabine in various treatment strategies. Concomitant use of clofarabine, cytarabine, and etoposide was confirmed to be safe and effective in two independent trials. Based on the promising results when used as a salvage regimen, clofarabine is now being investigated for its potential to become part of frontline protocols
Colourful Poincaré symmetry, gravity and particle actions
We construct a generalisation of the three-dimensional Poincar\'e algebra that also includes a colour symmetry factor. This algebra can be used to define coloured Poincar\'e gravity in three space-time dimensions as well as to study generalisations of massive and massless free particle models. We present various such generalised particle models that differ in which orbits of the coloured Poincar\'e symmetry are described. Our approach can be seen as a stepping stone towards the description of particles interacting with a non-abelian background field or as a starting point for a worldline formulation of an associated quantum field theory
Curvature corrections and Kac-Moody compatibility conditions
We study possible restrictions on the structure of curvature corrections to
gravitational theories in the context of their corresponding Kac--Moody
algebras, following the initial work on E10 in Class. Quant. Grav. 22 (2005)
2849. We first emphasize that the leading quantum corrections of M-theory can
be naturally interpreted in terms of (non-gravity) fundamental weights of E10.
We then heuristically explore the extent to which this remark can be
generalized to all over-extended algebras by determining which curvature
corrections are compatible with their weight structure, and by comparing these
curvature terms with known results on the quantum corrections for the
corresponding gravitational theories.Comment: 27 page
An epidemiological perspective of substance use among high school pupils in rural KwaZulu-Natal
Objectives. To investigate prevalence and the factors influencing substance use among rural high school pupils in KwaZulu-Natal in order to develop and implement intervention programmes.Design. Cross-sectional study.Setting. Twenty-eight high schools in southern KwaZulu-Natal.Subjects. One thousand three hundred and eighteen grade 10 pupils.Outcome measures. An anonymous self-reporting questionnaire was used to investigate the use of alcohol, tobacco (cigarettes), cannabis and solvents.Results. Of the male scholars, 52.9% (95% confidence interval (CI): 45.4- 60.3) reported ever using alcohol, 16.9% (CI: 11.5 - 24.0) reported using cannabis, and 13.1% (CI: 7.2 - 22.5) had smoked more than one cigarette daily. Among male pupils 45.5% (CI: 38.6- 52.6) had inhaled benzine and 34.6% (CI: 28.0- 41.8), thinners; 7.4% (CI: 3.4 - 15.2) had used cocaine and 4.1% (CI: 1.0 - 10.6), crack. Female pupils reported significantly less use of alcohol (25.5%, CI: 17.6 - 35.3), cannabis (2.3%, CI: 1.3 - 4.1), cigarettes (more than one daily) (2.0%, CI: 1.0 - 4.1), and inhalation of benzine (18.8%, CI: 13.8 - 25.2) and thinners (10.8%, CI: 7.2 - 16). Logistical regression indicated that the odds of smoking cigarettes increased significantly (p < 0.0005) with use of the other substances.Conclusion. The results of this study confirm the prevalence of multi-substance use among pupils at the majority of rural high schools in this district and the need for targeted interventions to reduce/prevent this
Burden of asymptomatic malaria among a tribal population in a forested village of central India: a hidden challenge for malaria control in India.
OBJECTIVE: Chhattisgarh in India is a malaria-endemic state with seven southern districts that contributes approximately 50-60% of the reported malaria cases in the state every year. The problem is further complicated due to asymptomatic malaria cases which are largely responsible for persistent transmission. This study was undertaken in one of the forested villages of the Keshkal subdistrict in Kondagaon district to ascertain the proportion of the population harbouring subclinical malarial infections. STUDY DESIGN: Community-based cross-sectional study. METHODS: Mass blood surveys were undertaken of the entire population of the village in the post-monsoon seasons of 2013 and 2014. Fingerprick blood smears were prepared from individuals of all ages to detect malaria infections in their blood. Individuals with fever at the time of the survey were tested with rapid diagnostic tests, and parasitaemia in thick blood smears was confirmed by microscopy. Malaria-positive cases were treated with anti-malarials in accordance with the national drug policy. RESULTS: Peripheral blood smears of 134 and 159 individuals, including children, were screened for malaria infection in 2013 and 2014, respectively. Overall, the malaria slide positivity rates were 27.6% and 27.7% in 2013 and 2014, respectively, and the prevalence rates of asymptomatic malaria were 20% and 22.8%. This study showed that, for two consecutive years, the prevalence of asymptomatic malaria infection was significantly higher among children aged ?14 years (34.4% and 34.1% for 2013 and 2014, respectively) compared with adults (15.2% and 18.2% for 2013 and 2014, respectively; P = 0.023 and 0.04, respectively). CONCLUSION: The number of asymptomatic malaria cases, especially Plasmodium falciparum, is significant, reinforcing the underlying challenge facing the malaria elimination programme in India
Ehlers symmetry at the next derivative order
We analyse four-dimensional gravity in the presence of general curvature
squared corrections and show that Ehlers' SL(2,R) symmetry, which appears in
the reduction of standard gravity to three dimensions, is preserved by the
correction terms. The mechanism allowing this is a correction of the SL(2,R)
transformation laws which resolves problems with the different scaling
behaviour of various terms occurring in the reduction.Comment: 13 pages. v2: updated referenc
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