Flat Dielectric Grating Reflectors with High Focusing Power

Sub-wavelength dielectric gratings (SWG) have emerged recently as a promising alternative to distributed-Bragg-reflection (DBR) dielectric stacks for broadband, high-reflectivity filtering applications. A SWG structure composed of a single dielectric layer with the appropriate patterning can sometimes perform as well as thirty or forty dielectric DBR layers, while providing new functionalities such as polarization control and near-field amplification. In this paper, we introduce a remarkable property of grating mirrors that cannot be realized by their DBR counterpart: we show that a non-periodic patterning of the grating surface can give full control over the phase front of reflected light while maintaining a high reflectivity. This new feature of dielectric gratings could have a substantial impact on a number of applications that depend on low-cost, compact optical components, from laser cavities to CD/DVD read/write heads.Comment: submitted to Nature Photonic

Predicted Causality in Decision Making: The Role of Culture

In the wider sense, decision making is embedded in the problem-solving process and its many stages (Davidson and Sternberg, 2003; Güss et al., 2010). In the narrow sense, decision making is understood as the ability to select one of several alternatives and to act accordingly (Güss 2004). Previous research has often focused on decision making in relatively predictable environments with clear goals (e.g., expected utility theory of von Neumann and Morgenstern, 1944). In recent decades the focus has been on decision making heuristics, i.e., strategies or rules of thumb, applied in uncertain situations (e.g., Tversky and Kahneman, 1974; Simon, 1979; Gigerenzer and Gaissmaier, 2011). Causality plays an important role in many cognitive processes – and causal cognition is itself influenced by culture (e.g., Norenzayan and Nisbett, 2000; Medin and Atran, 2004; Beller et al., 2009; Bender and Beller, 2011; for a controversial discussion of causal cognition, see Sperber et al., 1995). Causality is especially important during the decision-making process, because the decision maker has to predict what consequences specific decisions bring about before making a decision

Exergy intensity and environmental consequences of the medical face masks curtailing the COVID-19 pandemic: Malign bodyguard?

On January 30, 2020, the World Health Organization identified SARS-CoV-2 as a public health emergency of global concern. Accordingly, the demand for personal protective equipment (PPE), including medical face masks, has sharply risen compared with 2019. The new situation has led to a sharp increase in energy demand and the environmental impacts associated with these product systems. Hence, the pandemic's effects on the environmental consequences of various PPE types, such as medical face masks, should be assessed. In light of that, the current study aimed to identify the environmental hot-spots of medical face mask production and consumption by using life cycle assessment (LCA) and tried to provide solutions to mitigate the adverse impacts. Based on the results obtained, in 2020, medical face masks production using fossil-based plastics causes the loss of 2.03 × 103 disability-adjusted life years (DALYs); 1.63 × 108 PDF*m2*yr damage to ecosystem quality; the climate-damaging release of 2.13 × 109 kg CO2eq; and 5.65 × 1010 MJ damage to resources. Besides, annual medical face mask production results in 5.88 × 104 TJ demand for exergy. On the other hand, if used makes are not appropriately handled, they can lead to 4.99 × 105 Pt/yr additional damage to the environment in 2020 as determined by the EDIP 2003. Replacement of fossil-based plastics with bio-based plastics, at rates ranging from 10 to 100%, could mitigate the product's total yearly environmental damage by 4–43%, respectively. Our study calls attention to the environmental sustainability of PPE used to prevent virus transmission in the current and future pandemics

Tracheal agenesis as a rare cause of difficult intubation in a newborn with respiratory distress: a case report

<p>Abstract</p> <p>Introduction</p> <p>Tracheal agenesis is a very rare congenital airway anomaly. It may pose a great challenge to the first attending physician both in diagnosis and in establishing the airway during the first day of life.</p> <p>Case presentation</p> <p>We report a newborn Malay baby boy with trachea agenesis (type III by Floyd's classification) who presented with severe respiratory distress immediately after birth. Clinical diagnosis in this case was not straightforward, as it started with difficulty in intubation followed by an unsuccessful emergency tracheostomy in the neonatal intensive care unit. Urgent surgical neck exploration with endoscopic examination in the general operating theatre revealed the final diagnosis. The authors present a short description of the embryopathology and diagnostic criteria of the abnormality.</p> <p>Conclusion</p> <p>We hope this case presentation will be valuable in increasing the awareness of physicians about this rare cause of tracheal obstruction or difficult intubation.</p

Classical and Quantum Equations of Motion for a BTZ Black String in AdS Space

We investigate gravitational collapse of a $(3+1)$-dimensional BTZ black string in AdS space in the context of both classical and quantum mechanics. This is done by first deriving the conserved mass per unit length of the cylindrically symmetric domain wall, which is taken as the classical Hamiltonian of the black string. In the quantum mechanical context, we take primary interest in the behavior of the collapse near the horizon and near the origin (classical singularity) from the point of view of an infalling observer. In the absence of radiation, quantum effects near the horizon do not change the classical conclusions for an infalling observer, meaning that the horizon is not an obstacle for him/her. The most interesting quantum mechanical effect comes in when investigating near the origin. First, quantum effects are able to remove the classical singularity at the origin, since the wave function is non-singular at the origin. Second, the Schr\"odinger equation describing the behavior near the origin displays non-local effects, which depend on the energy density of the domain wall. This is manifest in that derivatives of the wavefunction at one point are related to the value of the wavefunction at some other distant point.Comment: 9 pages, 1 figure. Minor Clarification and corrections. Accepted for Publication in JHE

Scattering of Giant Holes

We study scalar excitations of high spin operators in N=4 super Yang-Mills theory, which are dual to solitons propagating on a long folded string in AdS_3 x S^1. In the spin chain description of the gauge theory, these are associated to holes in the magnon distribution in the sl(2,R) sector. We compute the all-loop hole S-matrix from the asymptotic Bethe ansatz, and expand in leading orders at weak and strong coupling. The worldsheet S-matrix of solitonic excitations on the GKP string is calculated using semiclassical quantization. We find an exact agreement between the gauge theory and string theory results.Comment: 13 pages. v2: minor corrections, references adde

Holographic Entanglement Entropy in P-wave Superconductor Phase Transition

We investigate the behavior of entanglement entropy across the holographic p-wave superconductor phase transition in an Einstein-Yang-Mills theory with a negative cosmological constant. The holographic entanglement entropy is calculated for a strip geometry at AdS boundary. It is found that the entanglement entropy undergoes a dramatic change as we tune the ratio of the gravitational constant to the Yang-Mills coupling, and that the entanglement entropy does behave as the thermal entropy of the background black holes. That is, the entanglement entropy will show the feature of the second order or first order phase transition when the ratio is changed. It indicates that the entanglement entropy is a good probe to investigate the properties of the holographic phase transition.Comment: 19 pages,15 figures, extended discussion in Sec.5, references adde

Hydrodynamics of a 5D Einstein-dilaton black hole solution and the corresponding BPS state

We apply the potential reconstruction approach to generate a series of asymptotically AdS (aAdS) black hole solutions, with a self-interacting bulk scalar field. Based on the method, we reproduce the pure AdS solution as a consistency check and we also generate a simple analytic 5D black hole solution. We then study various aspects of this solution, such as temperature, entropy density and conserved charges. Furthermore, we study the hydrodynamics of this black hole solution in the framework of fluid/gravity duality, e.g. the ratio of the shear viscosity to the entropy density. In a degenerate case of the 5D black hole solution, we find that the c function decreases monotonically from UV to IR as expected. Finally, we investigate the stability of the degenerate solution by studying the bosonic functional energy of the gravity and the Witten-Nester energy $E_{WN}$. We confirm that the degenerate solution is a BPS domain wall solution. The corresponding superpotential and the solution of the killing spinor equation are found explicitly.Comment: V2: 23 pages, no figure, minor changes, typos corrected, new references and comments added, version accepted by JHE

Influence of COVID-19 on the preventive health behaviours of indigenous peoples of Australia residing in New South Wales: a mixed-method study protocol.

Introduction Chronic conditions impact Indigenous Peoples of Australia at a much higher rate than non-Indigenous Australians. Attendance at the Medicare Benefits Scheme (MBS) supported Indigenous health checks are crucial to improve prevention and management of chronic health conditions. However, in conjunction with lifestyle and environmental factors, attendance rates at primary healthcare services for screening and treatment have fallen in Australia during the COVID-19 pandemic. This study aims to explore the influence of the COVID-19 pandemic on preventive health behaviours of Indigenous Australians and the associated barriers to, and enablers of, engagement with health services to formulate a targeted intervention strategy. Methods and analysis A concurrent mixed-methods study (comprising quantitative and qualitative data collection methods) will be employed. Descriptive analysis of MBS data about the characteristics of Indigenous Peoples of Australia claiming health assessment services will be performed. Generalised estimating equation regression models will be used to examine the use of health assessment services over time. Qualitative interviews informed by Indigenous research methods will be conducted. Interviews will investigate barriers to, and enablers of, engagement with health services. Thematic approach guided by the principles of indigenist praxis, storytelling and collaborative research will be used to analyse the interview data. The project commenced in July 2020 and will be completed by July 2022. Ethics and dissemination The project received ethics approval from the Aboriginal Health and Medical Research Council of New South Wales and the University of New England Human Research Ethics Committee. Findings will be disseminated via peer-reviewed journal articles, conferences, government and relevant stakeholder reports, and infographics