Quantum spacetime and the renormalization group: Progress and visions

The quest for a consistent theory which describes the quantum microstructure of spacetime seems to require some departure from the paradigms that have been followed in the construction of quantum theories for the other fundamental interactions. In this contribution we briefly review two approaches to quantum gravity, namely, asymptotically safe quantum gravity and tensor models, based on different theoretical assumptions. Nevertheless, the main goal is to find a universal continuum limit for such theories and we explain how coarse-graining techniques should be adapted to each case. Finally, we argue that although seemingly different, such approaches might be just two sides of the same coin.Comment: 14 pages, 4 figures, Proceedings of "Progress and Visions in Quantum Theory in View of Gravity: Bridging foundations of physics and mathematics", Leipzig, 201

Family memories in the home: contrasting physical and digital mementos

We carried out fieldwork to characterise and compare physical and digital mementos in the home. Physical mementos are highly valued, heterogeneous and support different types of recollection. Contrary to expectations, we found physical mementos are not purely representational, and can involve appropriating common objects and more idiosyncratic forms. In contrast, digital mementos were initially perceived as less valuable, although participants later reconsidered this. Digital mementos were somewhat limited in function and expression, largely involving representational photos and videos, and infrequently accessed. We explain these digital limitations and conclude with design guidelines for digital mementos, including better techniques for accessing and integrating these into everyday life, allowing them to acquire the symbolic associations and lasting value that characterise their physical counterparts

Practicing Teachers’ Attributions for the Behaviour of Students With Learning Disabilities and Attention-Deficit/Hyperactivity Disorder

More students with attention-deficit/hyperactivity disorder (ADHD) and learning disabilities (LD) are being taught within the regular education classroom than ever before even though children with these disorders often require additional educational supports. Therefore, it is critical that teachers understand the challenges experienced by these students, as well as feel efficacious when it comes to teaching and supporting them. Attribution theory is a widely used theoretical framework by which to explain teachers’ cognitions. We surveyed 151 practicing teachers and asked them to respond to items related to attributions for students’ behaviour and their teaching self-efficacy. First, we examined teachers’ perceptions of the primary cause of the difficulties experienced by students qualitatively. We open-coded responses and three major themes emerged: biology/genetics, the environment, and skill deficits. These themes differed somewhat depending on whether the student had ADHD or LD. Second, we examined the relationship between teachers’ attributions for student behaviours and their sense of teaching self-efficacy quantitatively. For students with ADHD, controllable attributions predicted teachers’ self-efficacy (β = .30, p = .005). For students with LD, controllable and internal attributions predicted teacher self-efficacy (β = .34, p = .001, β = .24, p = .009, respectively). Third, we examined the results of both analyses simultaneously to determine areas of convergence and divergence with respect to attribution theory. The results have implications for both teachers and students (e.g., attributional interventions designed to foster a sense of self-efficacy), as well as provide directions for future research and teacher training. Keywords: ADHD, LD, practicing teachers, attributions, self-efficacy, mixed-methods Le nombre d’élèves atteints du trouble du déficit de l'attention avec ou sans hyperactivité (TDAH) ou des troubles d’apprentissage (TA) sont intégrés plus que jamais aux classes ordinaires, même si les enfants affectés par ce type de difficultés ont souvent besoin d’un soutien éducationnel supplémentaire. Il est donc critique que les enseignants comprennent les défis que vivent ces élèves et que les enseignants se sentent efficaces dans l’enseignement et l’appui qu’ils leur apportent. La théorie attributive est un cadre théorique dont l’emploi est répandu pour expliquer les cognitions des enseignants. Au cours d’une enquête auprès de 151 enseignants en exercice, nous les avons interrogés au sujet des attributions relatives au comportement des élèves et de leur sentiment d’efficacité personnelle en enseignement. Nous avons d’abord étudié, qualitativement, les perceptions des enseignants quant à la première cause des difficultés que vivent les élèves. Trois thèmes majeurs se sont dégagés des réponses aux questions ouvertes : la biologie/la génétique, l’environnement et des lacunes sur le plan des habiletés. Ces thèmes variaient quelque peu selon que l’élève était atteint du TDAH ou des TA. Deuxièmement, nous avons étudié, quantitativement, le rapport entre les attributions des enseignants relatives au comportement des élèves et leur sentiment d’efficacité personnelle en enseignement. Par rapport aux élèves atteints du TDAH, les attributions contrôlables étaient prédictives du sentiment d’efficacité personnelle chez les enseignants (β = .30, p = .005). Relativement aux élèves atteints des TA, les attributions contrôlables et internes étaient prédictives du sentiment d’efficacité personnelle chez les enseignants (β = .34, p = .001, β = .24, p = .009, respectivement). En troisième lieu, nous avons étudié les résultats des deux analyses simultanément afin de déterminer les points de convergence et de divergence par rapport à la théorie attributive. Les résultats ont des retombées tant pour les enseignants que les élèves (par ex. des interventions attributionnelles conçues pour favoriser un sentiment d’efficacité personnelle) et ils proposent de nouvelles orientations en matière de recherche et formation des enseignants. Mots clés : TDAH, TA, enseignants en exercice, attributions, efficacité personnelle, méthodes mixte

On Abelian Multi-Chern-Simons Field Theories

In this paper a class of multi-Chern-Simons field theories which is relevant to the statistical mechanics of polymer systems is investigated. Motivated by the problems which one encounters in the treatment of these theories, a general procedure is presented to eliminate the Chern-Simons fields from their action. In this way it has been possible to derive an expression of the partition function of topologically linked polymers which depends explicitly on the topological numbers and does not have intractable nonlocal terms as it happened in previous approaches. The new formulation of multi-Chern-Simons field theories is then used to remove and clarify some inconsistencies and ambiguities which apparently affect field theoretical models of topologically linked polymers. Finally, the limit of disentangled polymers is discussed.Comment: 18 pages, plain LaTe

High AIDS-related mortality among young women in rural KwaZulu-Natal

Objective. To establish mortality rates and cause of death in a rural community in KwaZulu-Natal. This study was conducted as part of a demographic and health survey to assess the impact of HIV infection in this community. Methods. A cross-sectional survey was conducted between February and July 2004. The survey made use of structured questionnaires and verbal autopsies, which yielded detailed information at household level, including the demographic profile of residents, mortality rates and cause of mortality between February 2003 and February 2004.Results. The overall mortality rate in this community was 2.9 deaths per 100 person-years (95% confidence interval (CI): 2.5 - 3.3 per 100 person-years). The highest mortality rate among women occurred in the 30 - 34-year age group, while among men it occurred in the 35 - 39 and > 60-year age groups. Of the 185 verbal autopsies reported, 77 deaths (42%) were attributable to AIDS. The survey revealed that women aged 20 - 24 and men aged 35 - 39 years were bearing a disproportionately large burden of AIDS-related mortality in this community.Conclusion. AIDS-related mortality was found to be disproportionately high in young women in this small rural community, and the majority of deaths resulted from pulmonary tuberculosis. The need to strengthen prevention and treatment efforts in this and similar settings is highlighted

Effect of side-chain asymmetry on the intermolecular structure and order-disorder transition in alkyl-substituted polyfluorenes

We study relations among the side-chain asymmetry, structure, and order-disorder transition (ODT) in hairy-rod-type poly(9,9-dihexylfluorene) (PF6) with two identical side chains and atactic poly(9-octyl-9-methylfluorene) (PF1-8) with two different side chains per repeat. PF6 and PF1-8 organize into alternating side-chain and backbone layers that transform into an isotropic phase at T-ODT(PF6) and T-bi(ODT)(PF1-8). We interpret polymers in terms of monodisperse and bidisperse brushes and predict scenarios T-ODT <T-bi(ODT) and T-ODT similar to T-bi(ODT) for high and low grafting densities (the side-chain length above or below the average grafting distance). Calorimetry and x-ray scattering indicate the condition T-ODT(PF6) similar to T-bi(ODT)(PF1-8) following the low grafting prediction. PF6 side chains coming from the alternating backbone layers appear as two separate layers with thickness H(PF6), whereas PF1-8 side chains appear as an indistinguishable bilayer with a half thickness H-bilayer(PF1-8)/2 approximate to H(PF6). The low grafting density region is structurally possible but not certain for PF6 and confirmed for PF1-8.Peer reviewe

Biceps femoris long head morphology in youth competitive alpine skiers is associated with age, biological maturation and traumatic lower extremity injuries

Lower extremity injuries are common in competitive alpine skiers, and the knee and lower leg are often affected. The hamstring muscles, especially the biceps femoris long head (BFlh), can stabilize the knee and the hip and may counteract various adverse loading patterns during typical mechanisms leading to severe lower extremity injuries. The aim of the present study was to describe BFlh morphology in youth competitive alpine skiers in relation to sex, age and biological maturation and to investigate its association with the occurrence of traumatic lower extremity injuries in the upcoming season. 95 youth skiers underwent anthropometric measurements, maturity offset estimations and ultrasound assessment, followed by 12-months prospective injury surveillance. Unpaired t tests showed that the two sexes did not differ in BFlh morphology, including fascicle length (Lf), pennation angle (PA), muscle thickness (MT) and average anatomical cross-sectional area (ACSAavg). In contrast, U16 skiers had longer fascicles than U15 skiers (9.5 ± 1.3 cm vs 8.9 ± 1.3 cm, p < 0.05). Linear regression analyses revealed that maturity offset was associated with Lf (R2 = 0.129, p < 0.001), MT (R2 = 0.244, p < 0.001) and ACSAavg (R2 = 0.065, p = 0.007). No association was found between maturity offset and PA (p = 0.524). According to a binary logistic regression analysis, ACSAavg was significantly associated with the occurrence of traumatic lower extremity injuries (Chi-square = 4.627, p = 0.031, RNagelkerke2 = 0.064, Cohen f = 0.07). The present study showed that BFlh morphology is age- and biological maturation-dependent and that BFlh ACSAavg can be considered a relevant modifiable variable associated with lower extremity injuries in youth competitive alpine skiers

Acid-Labile Traceless Click Linker for Protein Transduction

Intracellular delivery of active proteins presents an interesting approach in research and therapy. We created a protein transduction shuttle based on a new traceless click linker that combines the advantages of click reactions with implementation of reversible pH-sensitive bonds. The azidomethyl-methylmaleic anhydride (AzMMMan) linker was found compatible with different click chemistries, demonstrated in bioreversible protein modification with dyes, polyethylene glycol, or a transduction carrier. Linkages were stable at physiological pH but reversible at the mild acidic pH of endosomes or lysosomes. We show that pH-reversible attachment of a defined endosome-destabilizing three-arm oligo(ethane amino)amide carrier generates an effective shuttle for protein delivery. The cargo protein nlsEGFP, when coupled via the traceless AzMMMan linker, experiences efficient cellular uptake and endosomal escape into the cytosol, followed by import into the nucleus. In contrast, irreversible linkage to the same shuttle hampers nuclear delivery of nlsEGFP which after uptake remains trapped in the cytosol. Successful intracellular delivery of bioactive ß-galactosidase as a model enzyme was also demonstrated using the pH-controlled shuttle system

Renormalization of the Hamiltonian and a geometric interpretation of asymptotic freedom

Using a novel approach to renormalization in the Hamiltonian formalism, we study the connection between asymptotic freedom and the renormalization group flow of the configuration space metric. It is argued that in asymptotically free theories the effective distance between configuration decreases as high momentum modes are integrated out.Comment: 22 pages, LaTeX, no figures; final version accepted in Phys.Rev.D; added reference and appendix with comment on solution of eq. (9) in the tex