Emergence and correspondence for string theory black holes

This is one of a pair of papers that give a historical-\emph{cum}-philosophical analysis of the endeavour to understand black hole entropy as a statistical mechanical entropy obtained by counting string-theoretic microstates. Both papers focus on Andrew Strominger and Cumrun Vafa's ground-breaking 1996 calculation, which analysed the black hole in terms of D-branes. The first paper gives a conceptual analysis of the Strominger-Vafa argument, and of several research efforts that it engendered. In this paper, we assess whether the black hole should be considered as emergent from the D-brane system, particularly in light of the role that duality plays in the argument. We further identify uses of the quantum-to-classical correspondence principle in string theory discussions of black holes, and compare these to the heuristics of earlier efforts in theory construction, in particular those of the old quantum theory

Dirac states with knobs on: interplay of external parameters and the surface electronic properties of 3D topological insulators

Topological insulators are a novel materials platform with high applications potential in fields ranging from spintronics to quantum computation. In the ongoing scientific effort to demonstrate controlled manipulation of their electronic structure by external means, stoichiometric variation and surface decoration are two effective approaches that have been followed. In ARPES experiments, both approaches are seen to lead to electronic band structure changes. Such approaches result in variations of the energy position of bulk and surface-related features and the creation of two-dimensional electron gases.The data presented here demonstrate that a third manipulation handle is accessible by utilizing the amount of illumination a topological insulator surface has been exposed to under typical experimental ARPES conditions. Our results show that this new, third, knob acts on an equal footing with stoichiometry and surface decoration as a modifier of the electronic band structure, and that it is in continuous competition with the latter. The data clearly point towards surface photovoltage and photo-induced desorption as the physical phenomena behind modifications of the electronic band structure under exposure to high-flux photons. We show that the interplay of these phenomena can minimize and even eliminate the adsorbate-related surface band bending on typical binary, ternary and quaternary Bi-based topological insulators. Including the influence of the sample temperature, these data set up a framework for the external control of the electronic band structure in topological insulator compounds in an ARPES setting. Four external knobs are available: bulk stoichiometry, surface decoration, temperature and photon exposure. These knobs can be used in conjunction to tune the band energies near the surface and consequently influence the topological properties of the relevant electronic states.Comment: 16 pages, 8 figure

Beyond aspect: will be -ing and shall be -ing

This article discusses the synchronic status and diachronic development of will be -ing and shall be -ing (as in I’ll be leaving at noon).2 Although available since at least Middle English, the constructions did not establish a significant foothold in standard English until the twentieth century. Both types are also more prevalent in British English (BrE) than American English (AmE). We argue that in present-day usage will/shall be -ing are aspectually underspecified: instances that clearly construe a situation as future-in-progress are in the minority. Similarly, although volition-neutrality has been identified as a key feature of will/shall be -ing, it is important to take account of other, generally richer meanings and associations, notably ‘future-as-matter-of-course’ (Leech 2004), ‘already-decided future’ (Huddleston & Pullum et al. 2002) and non-agentivity. Like volition-neutrality, these characteristics appear to be relevant not only in contemporary use, but also in their historical expansion. We show that the construction has evolved from progressive aspect towards more subjectivised evidential meaning

Long Term Thermal Stability In Air Of Ionic Liquid Based Alternative Heat Transfer Fluids For Clean Energy Production

The purpose of this study was to investigate the effect of long-term aging on the thermal stability and chemical structure of seven different ILs so as to explore their suitability for use as a heat transfer fluid. This was accomplished by heating the ILs for 15 weeks at 200�C in an oxidizing environment and performing subsequent analyses on the aged chemicals

Proton transfer or hemibonding? The structure and stability of radical cation clusters

The basin hopping search algorithm in conjunction with second-order Moller-Plesset perturbation theory is used to determine the lowest energy structures of the radical cation clusters (NH_3)_n^+, (H_2O)_n^+, (HF)_n^+, (PH_3)_n^+, (H_2S)_n^+ and (HCl)_n^+, where n=2-4. The energies of the most stable structures are subsequently evaluated using coupled cluster theory in conjunction with the aug-cc-pVTZ basis set. These cationic clusters can adopt two distinct structural types, with some clusters showing an unusual type of bonding, often referred to as hemibonding, while other clusters undergo proton transfer to give an ion and radical. It is found that proton transfer based structures are preferred by the (NH_3)_n+, (H_2O)_n^+, and (HF)_n^+ clusters while hemibonded structures are favoured by (PH_3)_n^+, (H_2S)_n^+ and (HCl)_n^+. These trends can be attributed to the relative strengths of the molecules and molecular cations as Brønsted bases and acids, respectively, and the strength of the interaction between the ion and radical in the ion-radical clusters

Some quit, others persist: similarities and disparities of healthcare providers' speech concerning obesity

Background Recent studies indicate that healthcare providers, especially in primary healthcare, have negative beliefs and attitudes towards obese, which are negatively affecting their practices by not taking this issue as seriously as they should and, therefore, compromising the success of obesity treatment. However, data is not conclusive and quantitative research is not being able to clarify how health professionals' practices and roles are affected by the way they perceive obesity and obese people. Method Semi-structured interviews about beliefs, attitudes and practices about obesity were conducted withe Portuguese general practitioners, nutritionists and nurses working in primary health care centers in the north of Portugal. Data was analyzed according to thematic analysis' procedures. Results The main themes indicate that all groups are concerned about the obesity pandemic and have similar negative beliefs and attitudes toward obese, who are described as being unmotivated, noncompliant and demonstrating a passive coping and a lack of understanding about the gravity of their condition. General practitioners, due to patients' lack of compliance and success, feel frustrated, have lower expectations of efficacy and are negative about their role in the treatment, giving up in most of the cases. Nutritionists and nurses demonstrate an active role, are persistent, perceived themselves as being able to positively modify obese motivation and believe in the success of the interventions, which, however, are described as a constant struggle between them and the patients. It seems to exist communication problems between these three groups. Discussion In order to achieve success, healthcare providers should be aware of how their beliefs and attitudes can influence their practices. Education and training concerning treatment options and communications skills should be improved as well as a bigger emphasis should be put on a multidisciplinary approach to obesity.Introdução Investigações recentes no âmbito da obesidade sugerem que as crenças, atitudes e práticas de vários profissionais de saúde, principalmente ao nível dos cuidados de saúde primários, parecem estar a influenciar negativamente o comportamento destes técnicos no tratamento desta doença, não lhe dando a devida importância e contribuindo para a manutenção das taxas de obesidade. As críticas têm apontado para a primazia de investigações quantitativas e para a ausência de estudos comparativos com diferentes grupos de profissionais de saúde. Método Neste estudo foram realizadas entrevistas semiestruturadas a médicos de família, nutricionistas e enfermeiros, a laborar em centros de saúde dos distritos de Braga, Porto e Aveiro. As entrevistas foram transcritas e analisadas, segundo os princípios da análise temática. Resultados Os 3 grupos apresentam crenças e atitudes negativas em relação aos obesos, que são descritos como desmotivados e passivos face ao tratamento, não aderindo na maioria das vezes, visto desvalorizarem a obesidade enquanto problema de saúde. Os médicos de família possuem baixas expectativas de sucesso, sentindo‐se frustrados com a falta de adesão, o que os leva a adotar uma postura passiva e resignada face ao tratamento. Os nutricionistas e enfermeiros percecionam‐se como agentes ativos, considerando‐se capazes de influenciar a motivação dos obesos; acreditam no seu sucesso, mas descrevem o processo como uma luta constante. Há várias referências a problemas de comunicação entre os 3 grupos de profissionais. Discussão Para uma maior eficácia no tratamento da obesidade torna‐se peremptório alertar os profissionais de saúde para o impacto que as suas crenças poderão exercer na prática, reforçar a abordagem multidisciplinar e promover o aumento dos conhecimentos e de opções de tratamento, e a melhoria da comunicação entre os vários profissionais(undefined)info:eu-repo/semantics/publishedVersio

The attentional blink is related to phonemic decoding, but not sight-word recognition, in typically reading adults

This research investigated the relationship between the attentional blink (AB) and reading in typical adults. The AB is a deficit in the processing of the second of two rapidly presented targets when it occurs in close temporal proximity to the first target. Specifically, this experiment examined whether the AB was related to both phonological and sight-word reading abilities, and whether the relationship was mediated by accuracy on a single-target rapid serial visual processing task (single-target accuracy). Undergraduate university students completed a battery of tests measuring reading ability, non-verbal intelligence, and rapid automatised naming, in addition to rapid serial visual presentation tasks in which they were required to identify either two (AB task) or one (single target task) target/s (outlined shapes: circle, square, diamond, cross, and triangle) in a stream of random-dot distractors. The duration of the AB was related to phonological reading (n=41, ß=-0.43): participants who exhibited longer ABs had poorer phonemic decoding skills. The AB was not related to sight-word reading. Single-target accuracy did not mediate the relationship between the AB and reading, but was significantly related to AB depth (non-linear fit, R2 = .50): depth reflects the maximal cost in T2 reporting accuracy in the AB. The differential relationship between the AB and phonological versus sight-word reading implicates common resources used for phonemic decoding and target consolidation, which may be involved in cognitive control. The relationship between single-target accuracy and the AB is discussed in terms of cognitive preparation