Partial non-renormalisation of the stress-tensor four-point function in N=4 SYM and AdS/CFT

We show that, although the correlator of four stress-tensor multiplets in N=4 SYM is known to have radiative corrections, certain linear combinations of its components are protected from perturbative renormalisation and remain at their free-field values. This result is valid for weak as well as for strong coupling and for any gauge group. Our argument uses Intriligator's insertion formula, and includes a proof that the possible contact term contributions cannot change the form of the amplitudes. Combining this new non-renormalisation theorem with Maldacena's conjecture allows us to make a prediction for the structure of the corresponding correlator in AdS supergravity. This is verified by first considerably simplifying the strong coupling expression obtained by recent supergravity calculations, and then showing that it does indeed exhibit the expected structure.Comment: 21 pages, no figure

Exceptional non-renormalization properties and OPE analysis of chiral four-point functions in N=4 SYM_4

We show that certain classes of apparently unprotected operators in N=4 SYM_4 do not receive quantum corrections as a consequence of a partial non-renormalization theorem for the 4-point function of chiral primary operators. We develop techniques yielding the asymptotic expansion of the 4-point function of CPOs up to order O(\lambda^2) and we perform a detailed OPE analysis. Our results reveal the existence of new non-renormalized operators of approximate dimension 6.Comment: an error in Sect. 4 corrected; references adde

Developing generalism in the South African context

The largest impact on the South African burden of disease will be made in community-based and primary healthcare (PHC) settings and not in referral hospitals. Medical generalism is an approach to the delivery of healthcare that routinely applies a broad and holistic perspective to the patient’s problems and is a feature of PHC. A multi-professional team of generalists, who share similar values and principles, is needed to make this a reality. Ward-based outreach teams include community health workers and nurses with essential support from doctors. Expert generalists – family physicians – are required to support PHC as well as provide care at the district hospital. All require sufficient training, at scale, with greater collaboration and integration between training programmes. District clinical specialist teams are both an opportunity and a threat. The value of medical generalism needs to be explained, advocated and communicated more actively.This article is based in part on keynote addresses given by Proff A C Howe and J F M Hugo at the 16th National Family Practitioners Conference in Cape Town, SA, in May 2013 themed ‘Reclaiming Generalism.’http://www.samj.org.zaam2014ay201

No Evidence Supporting Flare Driven High-Frequency Global Oscillations

The underlying physics that generates the excitations in the global low-frequency, < 5.3 mHz, solar acoustic power spectrum is a well known process that is attributed to solar convection; However, a definitive explanation as to what causes excitations in the high-frequency regime, > 5.3 mHz, has yet to be found. Karoff and Kjeldsen (Astrophys. J. 678, 73-76, 2008) concluded that there is a correlation between solar flares and the global high-frequency solar acoustic waves. We have used the Global Oscillations Network Group (GONG) helioseismic data in an attempt to verify Karoff and Kjeldsen (2008) results as well as compare the post-flare acoustic power spectrum to the pre-flare acoustic power spectrum for 31 solar flares. Among the 31 flares analyzed, we observe that a decrease in acoustic power after the solar flare is just as likely as an increase. Furthermore, while we do observe variations in acoustic power that are most likely associated with the usual p-modes associated with solar convection, these variations do not show any significant temporal association with flares. We find no evidence that consistently supports flare driven high-frequency waves.Comment: 20 pages, 9 figures, Accepted for publication in Solar Physic

Flop Transitions in M-theory Cosmology

We study flop-transitions for M-theory on Calabi-Yau three-folds and their applications to cosmology in the context of the effective five-dimensional supergravity theory. In particular, the additional hypermultiplet which becomes massless at the transition is included in the effective action. We find the potential for this hypermultiplet which includes quadratic and quartic terms as well as additional dependence on the Kahler moduli. By constructing explicit cosmological solutions, it is demonstrated that a flop-transition can indeed by achieved dynamically, as long as the hypermultiplet is set to zero. Once excitations of the hypermultiplet are taken into account we find that the transition is generically not completed but the system is stabilised close to the transition region. Regions of moduli space close to flop-transitions can, therefore, be viewed as preferred by the cosmological evolution.Comment: 18 pages, Latex, 8 eps-figures, typos correcte

Influence of childhood growth on asthma and lung function in adolescence

Background Low birth weight and rapid infant growth in early infancy are associated with increased risk of childhood asthma, but little is known about the role of postinfancy growth in asthmatic children. Objectives We sought to examine the associations of children's growth patterns with asthma, bronchial responsiveness, and lung function until adolescence. Methods Individual growth trajectories from birth until 10 years of age were estimated by using linear spline multilevel models for 9723 children participating in a population-based prospective cohort study. Current asthma at 8, 14, and 17 years of age was based on questionnaires. Lung function and bronchial responsiveness or reversibility were measured during clinic visits at 8 and 15 years of age. Results Rapid weight growth between 0 and 3 months of age was most consistently associated with increased risks of current asthma at the ages of 8 and 17 years, bronchial responsiveness at age 8 years, and bronchial reversibility at age 15 years. Rapid weight growth was associated with lung function values, with the strongest associations for weight gain between 3 and 7 years of age and higher forced vital capacity (FVC) and FEV1 values at age 15 years (0.12 [95% CI, 0.08 to 0.17] and 0.11 [95% CI, 0.07 to 0.15], z score per SD, respectively) and weight growth between 0 and 3 months of age and lower FEV1/FVC ratios at age 8 and 15 years (-0.13 [95% CI, -0.16 to -0.10] and -0.04 [95% CI, -0.07 to -0.01], z score per SD, respectively). Rapid length growth was associated with lower FVC and FVC1 values at age 15 years. Conclusion Faster weight growth in early childhood is associated with asthma and bronchial hyperresponsiveness, and faster weight growth across childhood is associated with higher FVC and FEV1 values

Establishment of a novel set of vectors for transformation of the dinoflagellate Amphidinium carterae

Peridinin-containing dinoflagellate algae have a chloroplast genome formed from plasmid-like minicircles. This fragmented genome has allowed us to develop a genetic modification methodology involving the use of biolistics to introduce artificial minicircles in Amphidinium carterae (Nimmo et al., 2019). The previously reported artificial minicircles were based on native minicircles containing either the psbA or atpB gene. Each artificial minicircle allowed expression of a single selectable marker instead of psbA or atpB. Here, we present two further artificial minicircles for use in transformation of A. carterae. One is based on the petD minicircle, allowing the expression of a single selectable marker. The second is based on the two-gene minicircle originally containing atpA and petB, and allows the dual expression of a selectable marker and a gene of interest. Our research suggest that all of the 20 or so minicircles in A. carterae are suitable for adaptation as artificial minicircles, allowing for the simultaneous introduction of multiple genes

On the Behavior of the Effective QCD Coupling alpha_tau(s) at Low Scales

The hadronic decays of the tau lepton can be used to determine the effective charge alpha_tau(m^2_tau') for a hypothetical tau-lepton with mass in the range 0 < m_tau' < m_tau. This definition provides a fundamental definition of the QCD coupling at low mass scales. We study the behavior of alpha_tau at low mass scales directly from first principles and without any renormalization-scheme dependence by looking at the experimental data from the OPAL Collaboration. The results are consistent with the freezing of the physical coupling at mass scales s = m^2_tau' of order 1 GeV^2 with a magnitude alpha_tau ~ 0.9 +/- 0.1.Comment: 15 pages, 4 figures, submitted to Physical Review D, added references, some text added, no results nor figures change