The Four-Loop Dressing Phase of N=4 SYM

We compute the dilatation generator in the su(2) sector of planar N=4 super Yang-Mills theory at four-loops. We use the known world-sheet scattering matrix to constrain the structure of the generator. The remaining few coefficients can be computed directly from Feynman diagrams. This allows us to confirm previous conjectures for the leading contribution to the dressing phase which is proportional to zeta(3).Comment: 19 pages, v2: referenced adde

Emission characteristics and dynamics of the stagnation layer in colliding laser produced plasmas

The expansion dynamics of ion and neutral species in laterally colliding laser produced aluminum plasmas have been investigated using time and space resolved optical emission spectroscopies and spectrally and angularly resolved fast imaging. The emission results highlight a difference in neutral atom and ion distributions in the stagnation layer where, at a time delay of 80 ns, the neutral atoms are localized in the vicinity of the target surface 1 mm from the target surface while singly and doubly charged ions lie predominantly at larger distances, 1.5 and 2 mm, respectively. The imaging results show that the ions were found to form a well defined, but compressed, stagnation layer at the collision front between the two seed plasmas at early times (Dt ~ 80 ns). On the other hand, the excited neutrals were observed to form a V-shaped emission feature at the outer regions of the collision front with enhanced neutral emission in the less dense, cooler regions of the stagnation layer

What Skills Do I Need to Teach Online? Researching Experienced Teacher Views of Essential Knowledge and Skills in Online Pedagogy as a Foundation for Designing Professional Development for Novice Teachers

As e-Learning continues to dominate educational services globally, the domain of online pedagogy continues to expand, and teaching in online, blended and hybrid classrooms now considered an essential element of teacher education in the many parts of Europe, Canada and the US. As a result, the need for professional development of higher education teachers has never been greater. An important precursor to designing effective teacher preparation programs is to establish what novice teachers need to know and do to be successful in virtual teaching spaces. The idea that professional development for online teaching needs to focus on instructional and communicative skills, not just the technology skills, is reinforced throughout the literature. This large international qualitative study was designed to investigate and explore the perceptions of experienced teachers of the skills and knowledge deemed essential for online teaching and the capacities they perceive as most important for effective e-Learning. Transformative learning theory formed the foundational theoretical framework for this study. The research problem identified was the lack of practitioner voices on the challenges that novice teachers experiences in their transition to online teaching and the perspective changes that happen when they reconsider their pedagogies. Results indicate that teachers need to transform their pedagogy when teaching in virtual spaces and this includes new roles, modes of interaction and discovery of engaging ways of teaching online that increase connectivity and interaction with students. Implications for professional development and practice in higher education are examined

EEG Source Imaging Indices of Cognitive Control Show Associations with Dopamine System Genes.

Cognitive or executive control is a critical mental ability, an important marker of mental illness, and among the most heritable of neurocognitive traits. Two candidate genes, catechol-O-methyltransferase (COMT) and DRD4, which both have a roles in the regulation of cortical dopamine, have been consistently associated with cognitive control. Here, we predicted that individuals with the COMT Met/Met allele would show improved response execution and inhibition as indexed by event-related potentials in a Go/NoGo task, while individuals with the DRD4 7-repeat allele would show impaired brain activity. We used independent component analysis (ICA) to separate brain source processes contributing to high-density EEG scalp signals recorded during the task. As expected, individuals with the DRD4 7-repeat polymorphism had reduced parietal P3 source and scalp responses to response (Go) compared to those without the 7-repeat. Contrary to our expectation, the COMT homozygous Met allele was associated with a smaller frontal P3 source and scalp response to response-inhibition (NoGo) stimuli, suggesting that while more dopamine in frontal cortical areas has advantages in some tasks, it may also compromise response inhibition function. An interaction effect emerged for P3 source responses to Go stimuli. These were reduced in those with both the 7-repeat DRD4 allele and either the COMT Val/Val or the Met/Met homozygous polymorphisms but not in those with the heterozygous Val/Met polymorphism. This epistatic interaction between DRD4 and COMT replicates findings that too little or too much dopamine impairs cognitive control. The anatomic and functional separated maximally independent cortical EEG sources proved more informative than scalp channel measures for genetic studies of brain function and thus better elucidate the complex mechanisms in psychiatric illness

Eliminating ambiguities for quantum corrections to strings moving in AdS4×CP3AdS_4\times \mathbb{CP}^3

We apply a physical principle, previously used to eliminate ambiguities in quantum corrections to the 2 dimensional kink, to the case of spinning strings moving in $AdS_4\times \mathbb{CP}^3$, thought of as another kind of two dimensional soliton. We find that this eliminates the ambiguities and selects the result compatible with AdS/CFT, providing a solid foundation for one of the previous calculations, which found agreement. The method can be applied to other classical string "solitons".Comment: 18 pages, latex; references added, comments added at end of section 4, a few words changed; footnote added on page 1

Contributions of Professor Martin Brasier to the study of early life, stratigraphy and biogeochemistry

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Comparative whisper vowel space for Singapore English and British English accents

Whispered speech, as a relatively common form of communications, has received little research effort in spite of its usefulness in everyday vocal communications. Apart from a few notable studies analysing the main whispered vowels and some quite general estimations of whispered speech characteristics, a classic vowel space determination has been lacking for whispers. Aligning with the previous published work which aimed to redress this shortfall by presenting a vowel formant space for whispers, this paper studies Singapore English (SgE) from this respect. Furthermore, by comparing the shift amounts between normal and whispered vowel formants in two different English accents, British West Midlands (WM) and SgE, the study also considers the question of generalisation of shift amount and direction for two dissimilar accent groupings. It is further suggested that the shift amounts for each vowel are almost consistent for F2 while these vary for F1, showing the role of accent in proposing a general correlation between normal and whispered vowels on first formant. This paper presents the results of the formant analysis, in terms of acoustic vowel space mappings, showing differences between normal and whispered speech for SgE, and compares this to results obtained from the analysis of more standard English