bluuebunny/crossref_metadata_2025 huggingface dataset:
Safety and Effectiveness of Additional Apical Preparation using a Rotary Heat-treated Nickel–Titanium file with Larger Diameter and Minimum Taper in Retreatment of Curved Root Canals
Authors: Pinto Jader Camilo , Torres Fernanda Ferrari Esteves , Santos-Junior Airton Oliveira , Duarte Marco Antonio Hungaro , Guerreiro-Tanomaru Juliane Maria , Tanomaru-Filho Mario
Published: February 2021

Objective The aim of this study was to investigate the effect of additional apical preparation using the ProDesign Logic (PDL) 50/.01 rotary heat-treated nickel–titanium (NiTi) file with a larger diameter and minimal taper for retreatment of curved root canals.

Materials and Methods Mesial curved root canals of 12 mandibular molars were prepared using PDL 25/.06 and filled using the continuous wave of condensation technique and AH Plus sealer. After retreatment using ProDesign S (PDS) 25/.08, PDL 25/.06 and PDL 35/05, a complementary procedure was performed with PDL 50/.01. Microcomputed tomography (micro-CT) scanning was performed before and after retreatment procedures. The cyclic fatigue resistance of unused PDS 25/.08, PDL 25/.06, PDL 35/.05 and PDL 50/.01 instruments (n = 12) was evaluated in a stainless-steel device.

Statistical Analysis Data on the volumes of the root canals and the remaining filling materials were submitted to the paired t-test. Cyclic fatigue resistance data was submitted to one-way ANOVA and Tukey’s tests (α = 0.05).

Results Use of PDL 50/.01 decreased the remaining filling materials in the apical third (p < 0.05). The root canal volume was similar in the cervical and middle thirds before and after preparation using PDL 50/.01 (p > 0.05). PDL 50/.01 presented the highest cyclic fatigue resistance (p < 0.05).

Conclusions Use of the PDL 50/.01 instrument as an additional apical preparation for retreatment of curved root canals improved filling material removal in the apical third, while maintaining the dentin in the cervical and middle thirds. In addition, PDL 50/.01 presented high-flexural resistance.
Derailed Cardiac Surgical Practice during COVID-19 Pandemic: Concerns and Proposed Solution Strategy
Authors: Vaswani Prateek , Sahu Manoj Kumar
Published: February 2021

The current ongoing novel corona virus disease 2019 (COVID 19) pandemic has led to reallocation of substantial hospital resources and workforce depriving the institution’s ability to handle the routine caseload. The sustenance of health care would require a comprehensive management plan and focused strategy. The cardiac surgical department would consume majority of critical care resources, hence, a balance should be sought between the resumption of routine surgeries and the emergency unavoidable ones. We have proposed an alternative plan to guide the formulation of a strategic comeback.
Off-Pump Coronary Artery Bypass Reduces Cardiac Death in Patients with Peripheral Arteriopathy
Authors: Bonacchi Massimo , Howe Rosemary , Micali Linda Renata , Weigel Daniel , Parise Orlando , Parise Gianmarco , Gelsomino Sandro
Published: February 2021

Objective The aim of this study was to investigate whether the use of off-pump coronary artery bypass (OPCAB) may enhance early outcomes in subjects with peripheral artery disease (PAD) undergoing coronary artery bypass grafting (CABG).

Methods We employed a propensity-score (PS) method to compare early postoperative results of OPCAB and on-pump CABG patients with associated PAD. The study population consisted of 1,961 patients: 284 in the OPCAB and 1,677 in the on-pump CABG group. The inverse probability of treatment weighting was used as PS method.

Results The incidence of death (1.2% [95% confidence interval, CI: –0.9 to 3.3%], p = 0.262), stroke (2.2% [95% CI: –1.4 to 5.7%], p = 0.235), acute kidney disease (1.5% [95% CI: –3.8 to 6.8%], p = 0.586), limb ischemia (3.2% [95% CI: –0.6 to 7.0%], p = 0.315), and low output syndrome (1.2% [95% CI: –0.9 to 3.3%], p = 0.262) did not differ between the two groups. On the other hand, the rate of cardiac death (1.2% [95% CI: –0.1 to 2.3%], p = 0.038) was significantly higher in on-pump CABG group.

Conclusions The OPCAB procedure considerably reduced the occurrence of cardiac death after coronary revascularization. This finding might suggest that the OPCAB procedure should be considered as the first option in patients with higher cardiovascular risk scores. Further research is warranted.
Correlation among Root Canal Configuration, Quality of Filling, and Its Sealability
Authors: Machado Ricardo , Koetz Ricardo , Comparin Daniel , Alberton Luiz Rômulo , da Fonseca Roberti Garcia Lucas , Xavier da Silva Neto Ulisses
Published: February 2021

Objective This study aimed to evaluate the existence of possible correlations among root canal configuration, quality of filling, and its sealability.

Materials and Methods Sixty human mandibular central incisors were selected for this study. The teeth were prepared with the Profile 04 system up to instrument 35/0.04 and irrigated with 2.5 mL of 2.5% sodium hypochlorite at each instrument change. Root canal filling was performed by the lateral compaction technique, using gutta-percha and an epoxy resin-based sealer (AH Plus) labeled with 0.1% Rhodamine B dye. Afterward, the specimens were submitted to fluid filtration tests to assess the sealability of the filling. Cross-sections were obtained at −3, −6, and −8 mm from the root apex and submitted to a metallographic treatment to determine the root canal configuration and the percentage of gutta-percha filled areas. The data were statistically analyzed by the Grubbs test. Pairs of correlations were analyzed by applying the Spearman test at a level of significance of 5%.

Results No correlation was observed among the analyzed variables as follows: root canal configuration versus filling quality (Spearman’s rho = 0.031); filling quality versus sealability (Spearman’s rho = 0.219); and root canal configuration versus sealability (Spearman’s rho = 0.184).

Conclusion The root canal configuration did not affect the quality of the filling and its sealability.
On-site low-power sensing nodes for distributed monitoring of heavy metal ions in water
Authors: Zhang Menglun , Zhang Xi , Niu Pengfei , Shen Tao , Yuan Yi , Bai Yuantao , Wang Zhilin
Published: February 2021

Heavy metal pollution in water environments poses a great threat to public health and to the ecological environment due to its high toxicity and non-degradability. However, many existing detection methods require laboratory-based bulky instruments and time-consuming manual operations. Although some on-site systems exist, they are difficult to deploy on a large scale owing to their large size and high cost. Here, we report a sensing node featuring low power consumption and low cost, achieved by integrating microsensor, microfluidic, and electronic modules into a compact size for automatic and scalable heavy metal pollution monitoring. Digital microfluidic and electrochemical sensing modules are integrated on a chip, thereby combining the procedures of sample pretreatment, electrochemical sensing, and waste removal for automatic and continuous monitoring. The feasibility of the platform is demonstrated by Pb2+ detection in tap water. With a 3500 mA·h battery, the compact sensing node could work for several years in principle. There is scope for further improvements to the system in terms of wider functionality and reductions in size, power consumption, and cost. The sensing node presented here is a strong candidate for distributed monitoring of water quality as an Internet-of-Things application.
Studies of a high-efficiency, long-pulse relativistic backward wave oscillator
Authors: Cao Yibing , Sun Jun , Song Zhimin , Fan Zhiqiang , Zhang Pinzhu , Wu Ping
Published: February 2021

A high-efficiency long-pulse relativistic backward wave oscillator (RBWO) operating in the C band is described. The electrodynamical structure of the RBWO consists of a resonance reflector, a slow-wave structure (SWS), an extractor, and a coaxial collector. To achieve high electron beam-electromagnetic wave interaction efficiency, a SWS for the RBWO is designed comprising of two structural segments with different corrugations that enables the gradually decreased electron beam axial velocity to better match the spatially constant electromagnetic wave phase velocity of the operating mode of the RBWO. To suppress electron emission and plasma formation on the inner surface of the electrodynamical structure, which is caused by a strong RF electric field, the RF electric field magnitude is optimized in computer simulations to be less than 700 kV/cm. A coaxial collector is designed to slow down the expansion of the collector plasma. The design of the RBWO is optimized in numerical simulations and its operation is validated in practical microwave-generation experiments. An output power of 3.3 GW is obtained in a practical experiment with a 796-kV, 10.3-kA electron beam guided by an external magnetic field of 2.2 T. The RBWO efficiency and microwave pulse width are measured in the experiment and found to be about 40% and 100 ns, respectively.
Mechanical behavior of ultralight nickel metamaterial
Authors: Rajak Pankaj , Nakano Aiichiro , Vashishta Priya , Kalia Rajiv
Published: February 2021

The mechanical response of ultralight kagomé structures consisting of hollow nickel (Ni) nanotubes and solid Ni nanorods to compression is studied using molecular dynamics simulations. In both kagomé architectures, 16[112] Shockley partial dislocations and twin formation are observed under compression. The structure made from solid nanorods shows deformation near both the nodes and beams of the kagomé lattice. The hollow kagomé architecture has a higher yield point than the solid kagomé structure. The deformation in the hollow nanotube structure is mostly localized in the nodal region for strains less than 11%. At higher strains, the deformation sets in all the struts and nodes of the hollow kagomé lattice. Owing to this two-stage deformation mechanism, the hollow Ni nanotube kagomé structure shows less bending and greater toughness than the solid Ni nanorod kagomé architecture.
Computational study of a novel microwave excited plasma sensor for aerodynamic flows
Authors: Karpatne Anand , Sharma Ashish , Sirohi Jayant , Raja Laxminarayan L.
Published: February 2021

We present a computational study that demonstrates the concept of a microwave excited plasma flow sensor. The geometric configuration consists of an array of circularly arranged “receiver” (ground) electrodes that surround a central “transmitter” (excited) electrode that is flush mounted on a surface exposed to incident flow. Microwave excitation is used to strike a low-temperature plasma between the transmitter electrode and the receiver electrode. Depending on the flow direction, a more intense plasma kernel is formed between the transmitter electrode and the downstream electrode for sufficiently strong excitation conditions. The differential current between the receiver electrodes is used to establish the flow direction and magnitude. The computational model establishes the effectiveness of the concept as a flow sensor. Parametric studies involving excitation voltages, flow velocities, scale lengths, electrode shape, and excitation frequency are performed. It is observed that the sensitivity of the device to the imposed flow is considerably improved with increasing excitation frequency in the microwave regime.
Explicit environmental and vibronic effects in simulations of linear and nonlinear optical spectroscopy
Authors: Shedge Sapana V. , Zuehlsdorff Tim J. , Khanna Ajay , Conley Stacey , Isborn Christine M.
Published: February 2021

Accurately simulating the linear and nonlinear electronic spectra of condensed phase systems and accounting for all physical phenomena contributing to spectral line shapes presents a significant challenge. Vibronic transitions can be captured through a harmonic model generated from the normal modes of a chromophore, but it is challenging to also include the effects of specific chromophore–environment interactions within such a model. We work to overcome this limitation by combining approaches to account for both explicit environment interactions and vibronic couplings for simulating both linear and nonlinear optical spectra. We present and show results for three approaches of varying computational cost for combining ensemble sampling of chromophore–environment configurations with Franck–Condon line shapes for simulating linear spectra. We present two analogous approaches for nonlinear spectra. Simulated absorption spectra and two-dimensional electronic spectra (2DES) are presented for the Nile red chromophore in different solvent environments. Employing an average Franck–Condon or 2DES line shape appears to be a promising method for simulating linear and nonlinear spectroscopy for a chromophore in the condensed phase.
Kinematics of slip-induced rotation for uniaxial shock or ramp compression
Authors: Heighway P. G. , Wark J. S.
Published: February 2021

When a metallic specimen is plastically deformed, its underlying crystal structure must often rotate in order to comply with its macroscopic boundary conditions. There is growing interest within the dynamic-compression community in exploiting x-ray diffraction measurements of lattice rotation to infer which combinations of plasticity mechanisms are operative in uniaxially shock- or ramp-compressed crystals, thus informing materials science at the greatest extremes of pressure and strain rate. However, it is not widely appreciated that several of the existing models linking rotation to slip activity are fundamentally inapplicable to a planar compression scenario. We present molecular dynamics simulations of single crystals suffering true uniaxial strain and show that the Schmid and Taylor analyses used in traditional materials science fail to predict the ensuing lattice rotation. We propose a simple alternative framework based on the elastoplastic decomposition that successfully recovers the observed rotation for these single crystals and can further be used to identify the operative slip systems and the amount of activity upon them in the idealized cases of single and double slip.
The five line-of-sight neutron time-of-flight (nToF) suite on the National Ignition Facility (NIF)
Authors: Moore A. S. , Hartouni E. P. , Schlossberg D. , Kerr S. , Eckart M. , Carrera J. , Ma L. , Waltz C. , Barker D. , Gjemso J. , Mariscal E. , Grim G. , Kilkenny J.
Published: February 2021

Measurement of the neutron spectrum from inertial confinement fusion implosions is one of the primary diagnostics of implosion performance. Analysis of the spectrum gives access to quantities such as neutron yield, hot-spot velocity, apparent ion temperature, and compressed fuel ρr through measurement of the down-scatter ratio. On the National Ignition Facility, the neutron time-of-flight suite has been upgraded to include five independent, collimated lines of sight, each comprising a high dynamic range bibenzyl/diphenylacetylene-stilbene scintillator [R. Hatarik et al., Plasma Fusion Res. 9, 4404104 (2014)] and high-speed fused silica Cherenkov detectors [A. S. Moore et al., Rev. Sci. Instrum. 89, 10I120 (2018)].
Graphite intercalation compound (GIC) crystal monochromators for cold neutron instruments: Characterization of KC24 by time-of-flight neutron diffraction
Authors: Dennison Andrew J. C. , Devishvili Anton , Gutfreund Philipp , Cubitt Robert , Vorobiev Alexei , Zabel Hartmut , Wolff Max
Published: February 2021

Graphite intercalation compounds (GICs) are a group of layered materials that are suitable as monochromators for cold neutrons. KC24 is a particularly interesting compound in this regard as it features a large c-axis lattice spacing of 8.74 Å, high reflectivity, and the possibility to produce large crystals with mosaicity that matches the beam divergence of cold neutron guides. GICs can be synthesized with different levels of intercalation, known as the stage of the compounds. Each stage displays a specific d-spacing. Impure GIC-monochromators containing multiple stages produce mixing of neutron wavelengths, which complicates data analysis on neutron reflectometers. We discuss the implications of GIC crystal purity and stage contamination for neutron reflectometry and show how GIC crystals can be characterized by time-of-flight neutron diffraction providing an efficient and quantifiable measure of the reflected wavelength spectrum. This allows taking into account multiple wavelength contaminations and ascertains the robustness of reflectometry measurements.
Microsecond dynamics in proteins by two-dimensional ESR. II. Addressing computational challenges
Authors: Gupta Pranav , Chaudhari Kevin , Freed Jack H.
Published: February 2021

Two-dimensional electron–electron double resonance (2D-ELDOR) provides extensive insight into molecular motions. Recent developments permitting experiments at higher frequencies (95 GHz) provide molecular orientational resolution, enabling a clearer description of the nature of the motions. In previous work, we provided simulations for the case of domain motions within proteins that are themselves slowly tumbling in a solution. In order to perform these simulations, it was found that the standard approach of solving the relevant stochastic Liouville equation using the efficient Lanczos algorithm for this case breaks down, so algorithms were employed that rely on the Arnoldi iteration. While they lead to accurate simulations, they are very time-consuming. In this work, we focus on a variant known as the rational Arnoldi algorithm. We show that this can achieve a significant reduction in computation time. The stochastic Liouville matrix, which is of very large dimension, N, is first reduced to a much smaller dimension, m, e.g., from N ∼ O(104) to m ∼ 60, that spans the relevant Krylov subspace from which the spectrum is predicted. This requires the selection of the m frequency shifts to be utilized. A method of adaptive shift choice is introduced to optimize this selection. We also find that these procedures help in optimizing the pruning procedure that greatly reduces the dimension of the initial N dimensional stochastic Liouville matrix in such subsequent computations.
Thermal equation of state study of polymorphic phases of Y2O3
Authors: Şavklıyıldız İlyas
Published: February 2021

Pressure and temperature dependences of the unit cell volumes of Y2O3’s three polymorphs (cubic, monoclinic, and hexagonal) have been measured by synchrotron energy dispersive x-ray diffraction in conjunction with a cubic anvil technique to pressures and temperatures up to 7.5 GPa and 1073 K, respectively. The measured pressure–volume–temperature (P–V–T) data were used to obtain thermoelastic parameters of the polymorphs by fitting the modified high temperature third-order Birch–Murnaghan equation of state and a thermal pressure approach. The thermoelastic properties that were determined in this study are the ambient bulk modulus with fixed pressure derivative of the bulk modulus (K0′=4.0), the isobaric temperature derivative of the bulk modulus (∂K/∂T)P, the volumetric thermal expansion coefficient along with the isothermal pressure derivative of thermal expansion (∂α/∂P)T, and the isometric temperature derivative of the bulk modulus (∂K/∂T)V. The ambient bulk modulus for cubic [152(7) GPa] and monoclinic [197(9) GPa] polymorphs agrees well with previous reports. There is no precedence for all other thermophysical properties of all three polymorphs of Y2O3 reported in this study. For instance, (∂K/∂T)P is the highest for the monoclinic polymorph, while (∂α/∂P)T and (∂K/∂T)V are the highest for the cubic polymorph. The results of this study add to the stock of knowledge on the thermophysical properties of Y2O3, which is a technologically relevant solid state material.
Neural stem cells secreting bispecific T cell engager to induce selective antiglioma activity
Authors: Pituch Katarzyna C. , Zannikou Markella , Ilut Liliana , Xiao Ting , Chastkofsky Michael , Sukhanova Madina , Bertolino Nicola , Procissi Daniele , Amidei Christina , Horbinski Craig M. , Aboody Karen S. , James C. David , Lesniak Maciej S. , Balyasnikova Irina V.
Published: February 2021

Significance

Glioblastoma (GBM) is the most aggressive and lethal brain tumor in adults. The GBM microenvironment is highly immunosuppressive, rendering T cells incapable of recognizing and eliminating malignant cells. We developed bispecific T cell engagers (BiTEs) that successfully engage patients' T cells to attack and kill GBM expressing interleukin 13 receptor alpha 2 (IL13Rα2). Neural stem cells (NSCs) engineered to secrete BiTE migrate readily within the brain tissue to established tumors and produce BiTE protein within the malignant tissue. Treatment of animals bearing IL13Rα2-expressing patient-derived GBM xenografts with therapeutic NSCs resulted in significant survival benefits in mice. These results show an exciting potential of NSCs as a delivery platform for BiTE therapy to improve outcomes for GBM patients.
The amino-terminal domain of GluA1 mediates LTP maintenance via interaction with neuroplastin-65
Authors: Jiang Chao-Hua , Wei Mengping , Zhang Chen , Shi Yun Stone
Published: February 2021

Significance

Long-term potentiation (LTP), the communication between neurons that is potentiated upon strong stimulus, is an important cellular mechanism underlying learning and memory. Mechanistically, LTP expression involves AMPA-type glutamate receptors insertion into synapses (initiation) and trapped at the synapses for an extended period of time (maintenance). Here, we show that the amino-terminal domain of GluA1, a subunit of AMPA receptors, selectively interacts with the adhesion protein Np65, and this interaction is required for the synaptic anchoring of AMPA receptors during LTP. Our study reveals a molecular mechanism underlying GluA1-dependent LTP maintenance.
Pragmatic functions of question-answer sequences in Italian legal examinations and TV interviews with politicians
Authors: Gnisci Augusto
Published: February 2021

The aim of this chapter is to identify the sequential relationship between coerciveness of questions and equivocation of answers when the same 11 politicians were interviewed on TV, and also examined during a criminal trial. Two observers codified each of the 2,757 question-answer sequences of the sample (37 h of video recordings) for coercion and equivocation. The results show that the coerciveness of questions interacts with the context to determine the equivocation of the answer, and so does the equivocation for determining the coercion of the following question. The interactional asymmetry between politicians and questioners displays opposite patterns in the two contexts: in courtrooms, coercion depends strongly on the equivocation of the answer, but the answer depends more on the coercion exerted by the type of the context; on TV, however, equivocation depends strongly on coercion. The subsequent implications are discussed.
Formulation questions and responses in Korean TV talk show interactions
Authors: Kim Kyu-hyun , Suh Kyung-Hee
Published: February 2021

This chapter examines the sequence-organizational role of the host’s formulation questions and the guest’s responses in entertainment-oriented Korean talk-shows. Constructed as a ‘follow-up’ re-presenting the upshot of the guest’s response on the host’s terms, the host’s formulation questions mediate sequence expansion through which an ‘information-oriented’ sequence is transited to an ‘affectively-loaded’ assessment sequence. This transition, contingent on the guest’s confirmation, is co-constructively accomplished; the host’s enticement of the guest’s confirmation is embodied in the turn-design features of formulation questions rendering an ‘obvious’ gist of the guest’s response, or indexing the host’s agentivity and empathic stance. The host’s move to implicate the guest in his/her ‘master-sequential’ transition may be resisted, with the guest, through disconfirmation, promoting a master narrative of his/her own.
Utah Farm-Chef-Fork: Linking Rural Growers with Urban Chefs
Authors: Curtis Kynda R. , Roslynn Brain
Published: February 2021

Utah Farm-Chef-Fork is a State-wide programme set up in 2012 aimed at connecting growers and chefs. The programme’s primary goal is to ‘enhance community vitality and reduce food miles by connecting Utah growers and restaurants’ through workshops, mingles (meet and greets), farm and restaurant tours and other local-sourcing food events.

Information

Adapted from ‘Chapter 14: Utah Farm-Chef-Fork: Linking Rural Growers with Urban Chefs to Enhance local food Sourcing’. In: Slocum, S.L. and Kline, C. (eds)
Linking Urban and Rural Tourism
. CAB International, pp. 202-215.

© CAB International 2017
Managing Cruising and Tourism in the Arctic
Authors: Ward-Perkins David , Mou Jessica
Published: February 2021

The Arctic is a new frontier of tourism. Once considered the world’s largest and best-preserved natural environment, it is home to a fragile ecology and wildlife. The retreat of sea ice has opened it up for development, including for tourism to destinations like Greenland, Svalbard and Northern Russia.

Information

TEAM Tourism Consulting, 2020

© CAB International 2020
Blue Ridge Music Trails
Authors: Jackie Ellis
Published: February 2021

The Blue Ridge Music Trails is an initiative led by the Blue Ridge National Heritage Area Partnership and the North Carolina Arts Council, a division of the North Carolina Department of Cultural Resources. It is a multi-partner initiative: stakeholders include the arts councils and tourism agencies as facilitators and the music venues, event organizers, musicians and dancers on the front lines. It aims to create a thriving environment for the rich music heritage and traditions of the region to support musicians and residents and share traditional music experiences with visitors to raise interest in the authentic music of the region. In October 2018, Jackie Ellis spoke to Angie Chandler, Executive Director of the Blue Ridge National Heritage Area, and Laura Boosinger, Executive Director of the Madison County Arts Council and the case recounts their insight on this initiative.

Information

Adapted from ‘Chapter 2 Routes, Culture and Human Experience’. In: Ward-Perkins D. et al.,
Tourism Routes and Trails: Theory and Practice
. CABI, p. 16-30.

© CAB International 2020
Managing Carrying Capacity at Arches National Park
Authors: Manning R.E. , Anderson L.E.
Published: February 2021

Visitor use of Arches National Park has grown dramatically in the past few decades and now exceeds 1 million visits annually. This has led to the trampling of fragile soils and vegetation, as well as crowding on trails and at attraction sites. The National Park Service developed and applied its Visitor Experience and Resource Protection framework to measure and manage carrying capacity at Arches; the first national park to use a management-by-objectives framework for this purpose. The process has led to an insightful exploration of the balance between preservation of the environment and visitor experience.

Information

Adapted from ‘Chapter 8 – How Many Visitors is Too Many at Arches?’. In: Manning R.E. and Anderson L.E (eds)
Managing outdoor recreation: case studies in the National Parks
. CABI, pp. 71-75.

© CAB International 2012
Exploring the Case: Tourism Planning in the Slovak High Tatras
Authors: Ward-Perkins David
Published: February 2021

Introduction

This case narrates the different stages planning of tourism in a mountainous area of Slovakia over a couple of centuries, with particular attention to the highly structured planning of communist times. It can help academics and students of tourism, economics, history, rural planning and other disciplines understand how such areas were perceived and planned over time and the modern legacy of past planning policies.

For students studying the history of tourism, it provides a valuable perspective on how tourism evolved in the mountain resorts of central Europe and how decisions were taken at a policy level in the post-war communist era. The logic of that period is similar to that of many countries around the world today where planning is centralized.
Exploring the Case: The Challenge of Climate Change for Coastal Tourism in the Azores
Authors: Ward-Perkins David
Published: February 2021

Introduction

This case is interesting for researchers and students that are considering the impacts of climate change, the efforts to mitigate it and its relation to tourism.

The case presents a paradox. On the one hand, it addresses the global issue of climate change and the contributions made by the Azores Region towards carbon reduction. At the same time, it looks at climate change through the lens this region’s tourism industry – a primary concern being possible damage to tourism assets.

These two perspectives are – to some extent – contradictory, and readers should separate them clearly in the course of their analysis.
Exploring the Case: Slave Trade Heritage in Ghana
Authors: Ward-Perkins David
Published: February 2021

Introduction

This case recounts how Ghana Tourism Authority set up and managed a 2019 ‘year of return’ with planned follow-up activities, exploiting a very particular form of diaspora tourism.

The case should be studied alongside other examples of tourism that commemorate the exile of populations from their homelands.
Exploring the Case: Managing Cruising and Tourism in the Arctic
Authors: Ward-Perkins David
Published: February 2021

Introduction

This is a story of relevance, urgency and conflict. Suffering more than any other world region from global warming, the Arctic has suddenly become accessible to human activity. The question is: Will we treat it with respect as we have failed to do with so many other natural areas of the planet?

There are many angles to the Arctic story, but the development of passenger shipping – in particular cruises – is a good introduction for professionals and students of tourism.
Exploring the Case: Catalonia, a Food Hub
Authors: Ward-Perkins David
Published: February 2021

Introduction

In the second half of the 20th century, many consumers became concerned about the increasing mechanization and standardization of food. At the same time, they were being exposed, through travel and global media, to food from around the world. These two influences have helped shape their perception of the countries concerned.

The perception of the country or region’s food influences the choice of destination of many tourists. That region’s capacity to produce, prepare and serve quality food has become an important tourism asset. The world of tourism and the world of food production have now become, in many destinations, inextricably linked.

Nowhere is this mix – this dependency of one on the other – more evident than in Catalonia, where the connection is made stronger by a reputation for high gastronomy, represented by chefs that are worldwide celebrities.

This is an excellent case for study for those who seek to understand what a food hub is, and how this alchemy works.
Exploring the Case: Women’s Empowerment in an Indian Trekking Company
Authors: Ward-Perkins David
Published: February 2021

Introduction

The case is enlightening for researchers and students interested in exploring gender roles in tourism, because it goes beyond the surface story – the inspiring initiative of Thinlas Chorol and the courage of her co-workers – to try and understand how these women perceive their role.
Exploring the Case: Managing Carrying Capacity at Arches National Park
Authors: Ward-Perkins David
Published: February 2021

Introduction

The question of carrying capacity is one faced by many protected natural areas. It might appear simple: if the number of visitors is such that it risks damaging the environment or biodiversity, then that number should be restricted or the visitor flow modified. On closer examination, the issues raised are complex. How do you define ‘damage’? How do you establish that a number is too high? Is it too high only at certain moments or in certain places? Can visitor behaviour be influenced? If one imposes restrictions, should all visitors be treated alike, or should some have priority?

The more we consider carrying capacity, the more we realize that it is connected to many other issues. The case of Arches gives us an insight, therefore, on how a National Park Authority approaches visitor management as a whole.
Elastic electron collisions with trimethyl phosphate
Authors: Bardela F P , da Silva A J , da Mata V A S , Homem M G P , Iga I , Sugohara R T , Fujimoto M M
Published: February 2021

An experimental investigation of elastic electron scattering by trimethyl phosphate (C3H9PO4) is presented. Differential cross sections were measured in the 5–800 eV and 10°–130° and from these data momentum-transfer cross sections were derived. Calculations of the scattering cross sections in the intermediate energy range were performed within the independent atom model framework at static-exchange-polarization plus absorption level of approximation. The comparison between our measured and calculated results presents, in general, a good agreement.
Impact of angular irradiance distributions on coupling gains and energy yield of cell interconnection designs in silicon solar modules in tracking and fixed systems
Authors: Haedrich Ingrid , Ernst Marco
Published: February 2021

Cell interconnector designs such as light redirecting films (LRFs) and various geometric ribbon layouts are all aimed at improving the performance of crystalline silicon solar modules. However, due to the usually specular reflecting surface, the angular-dependent module performance, which is typically quantified with an incidence angle modifier, depends on the rotation of the module. We find that typical power measurements under standard test conditions at 1000 W m−2 and 25 °C cell temperature are not suited to identify the best performing design in real-world conditions. In this work, we therefore determine the optimum ribbon geometry based on its simulated energy yield in common installation configurations for solar modules based on industry-standard full and half-cut solar cells. We compare the effects of planar, triangular, LRFs, pentagonal and wire ribbon geometries, as well as fixed optimal inclination, building-integrated (façade), and single-axis tracking installation scenarios of modules in portrait and landscape orientation. Energy yield gains of 1.8% can be achieved for full cell modules with LRFs or pentagonal ribbons in single-axis tracking installation compared to a reference module with five planar ribbons. Critically, we find that changing the module orientation to landscape reduces this energy yield gain by nearly 50% for the modules with LRFs. This directional dependence is significantly reduced with the pentagonal ribbon structure. The installation scenario can have a similarly dramatic impact. The expectation of power gains for certain designs inferred from standard test conditions may not only show significantly lower gains in annual energy yield, but may even lead to yield losses, especially for building-integrated photovoltaic systems. For a typical full-cell module, for example, we have found that LRFs perform 2.5% better than standard planar ribbons under standard test conditions but can result in a 0.2% lower annual yield in a façade installation. Therefore, to fully evaluate the effectiveness of a specific ribbon design, the annual energy yield must consider the angular irradiance distribution and weather conditions at a specific location, the installation scenario, and the module orientation.
SiC siligraphene: a novel SiC allotrope with wide tunable direct band gap and strong anisotropy
Authors: Long Hui , Hu Jianwei , Xie Xing , Hu Peiju , Wang Shaoxiong , Wen Minru , Zhang Xin , Wu Fugen , Dong Huafeng
Published: February 2021

By employing an ab initio evolutionary algorithm, we predict two novel metastable structures whose energies are just higher than g-SiC but lower than other two-dimensional (2D) SiC siligraphenes reported so far. One is composed of 4-6-8 C–Si rings named tho-SiC siligraphene and the other one is composed of 5-6-8 rings named pho-SiC siligraphene. They are almost equal in energy, but interestingly, our calculations demonstrate that tho-SiC siligraphene is a semiconductor like g-SiC, while pho-SiC siligraphene is a 2D metal. Additionally, unlike g-SiC which is very easy to switch from a direct band gap to indirect band gap semiconductor and exhibits homogenous isotropy characteristic under biaxial strains, tho-SiC siligraphene keeps a consistently direct band gap from 1.02 eV to 1.98 eV as the uniaxial strain increases from −9% to 9% and it shows strong anisotropic electronic structures. The obtained calculation results indicate that tho-SiC siligraphene may be a better candidate than g-SiC in the application of light-emitting devices in the future.
Encoded injection of microbubbles to improve flow velocity measurements using cross-correlation technique
Authors: Desmond Kenneth W , Hunter Gary L
Published: February 2021

We present techniques to measure fluid flow rates in single- and multi-phase fluid flows by detecting the motion of injected tracers. Our methods exploit acoustic impedance differences between liquids and gases to allow one to sense the presence of micron-sized gas bubbles in a liquid when it is irradiated with ultrasonic energy. By cross-correlating signals at multiple locations along the path of flow, the velocity of the moving fluid can be accurately estimated. We report experimental results in single- and two-phase fluid flows and describe the methodologies used in each case that are necessary to enable accurate measurements. In cases of single- and two- phase flows, respectively, flow rates can be measured to less than 5% and less than 10%–15% of known flow rates. While our experiments leveraged differences in acoustic properties, the methods may be generalized to other means of measurement.
Large magnetic anisotropy in an OsIr dimer anchored in defective graphene
Authors: Navrátil Jan , Błoński Piotr , Otyepka Michal
Published: February 2021

Single-atom magnets represent the ultimate limit of magnetic data storage. The identification of substrates that anchor atom-sized magnets firmly and, thus, prevent their diffusion and large magnetic anisotropy has been at the centre of intense research efforts for a long time. Using density functional theory we show the binding of transition metal (TM) atoms in defect sites in the graphene lattice: single vacancy and double vacancy, both pristine and decorated by pyridinic nitrogen atoms, are energetically more favourable than away from the centre of defects, which could be used for engineering the position of TMs with atomic precision. Relativistic calculations revealed magnetic anisotropy energy (MAE) of ∼10 meV for Ir@NSV with an easy axis parallel to the graphene plane. MAE can be remarkably boosted to 50 meV for OsIr@NSV with the easy axis perpendicular to the graphene plane, which paves the way to the storage density of ∼490 Tb/inch2 with the blocking temperature of 14 K assuming the relaxation time of 10 years. Magnetic anisotropy is discussed based on the relativistic electronic structures. The influence of an orbital-dependent on-site Coulomb repulsion U and a non-local correlation functional optB86b-vdW on MAE is also discussed.
Does binding energy bind?
Authors: Kızılcık Hasan Şahin
Published: February 2021

The aim of this study is to draw attention to the language-based misconceptions and confusions about the term binding energy and to make suggestions to educators on this issue.
Calibrated uncertainty estimation for interpretable proton computed tomography image correction using Bayesian deep learning
Authors: Nomura Yusuke , Tanaka Sodai , Wang Jeff , Shirato Hiroki , Shimizu Shinichi , Xing Lei
Published: February 2021

Integrated-type proton computed tomography (pCT) measures proton stopping power ratio (SPR) images for proton therapy treatment planning, but its image quality is degraded due to noise and scatter. Although several correction methods have been proposed, techniques that include estimation of uncertainty are limited. This study proposes a novel uncertainty-aware pCT image correction method using a Bayesian convolutional neural network (BCNN). A DenseNet-based BCNN was constructed to predict both a corrected SPR image and its uncertainty from a noisy SPR image. A total 432 noisy SPR images of 6 non-anthropomorphic and 3 head phantoms were collected with Monte Carlo simulations, while true noise-free images were calculated with known geometric and chemical components. Heteroscedastic loss and deep ensemble techniques were performed to estimate aleatoric and epistemic uncertainties by training 25 unique BCNN models. 200-epoch end-to-end training was performed for each model independently. Feasibility of the predicted uncertainty was demonstrated after applying two post-hoc calibrations and calculating spot-specific path length uncertainty distribution. For evaluation, accuracy of head SPR images and water-equivalent thickness (WET) corrected by the trained BCNN models was compared with a conventional method and non-Bayesian CNN model. BCNN-corrected SPR images represent noise-free images with high accuracy. Mean absolute error in test data was improved from 0.263 for uncorrected images to 0.0538 for BCNN-corrected images. Moreover, the calibrated uncertainty represents accurate confidence levels, and the BCNN-corrected calibrated WET was more accurate than non-Bayesian CNN with high statistical significance. Computation time for calculating one image and its uncertainties with 25 BCNN models is 0.7 s with a consumer grade GPU. Our model is able to predict accurate pCT images as well as two types of uncertainty. These uncertainties will be useful to identify potential cause of SPR errors and develop a spot-specific range margin criterion, toward elaboration of uncertainty-guided proton therapy.
Synthesizing optical spectra using computer-generated holography techniques
Authors: Holland Connor M , Lu Yukai , Cheuk Lawrence W
Published: February 2021

Experimental control and detection of atoms and molecules often rely on optical transitions between different electronic states. In many cases, substructure such as hyperfine or spin-rotation structure leads to the need for multiple optical frequencies spaced by MHz to GHz. The task of creating multiple optical frequencies—optical spectral engineering—becomes challenging when the number of frequencies becomes large, a situation that one could encounter in complex molecules and atoms in large magnetic fields. In this work, we point out a novel mapping between computer-generated holography (CGH) and spectrum generation via phase modulation, which is an established technique. Using this mapping, we synthesize arbitrary optical spectra by modulating a monochromatic light field with a time-dependent phase generated through CGH techniques. Our method is compatible with non-linear optical processes such as sum frequency generation and second harmonic generation. Additional requirements that arise from the finite lifetimes of excited states can also be satisfied in our approach. As a proof-of-principle demonstration, we generate spectra suitable for cycling photons on the X–B transition in CaF, and verify via optical Bloch equation simulations that one can achieve high photon scattering rates, which are important for fluorescent detection and laser cooling. Our method could offer significant simplifications in future experiments that would otherwise be prohibitively complex.
Non-similar mixed convection analysis for magnetic flow of second-grade nanofluid over a vertically stretching sheet
Authors: Raees Ammarah , Farooq Umer , Hussain Muzamil , Khan Waseem Asghar , Farooq Fozia Bashir
Published: February 2021

The aspiration of this research is to explore the impact of non-similar modeling for mixed convection in magnetized second-grade nanofluid flow. The flow is initiated by the stretching of a sheet at an exponential rate in the upward vertical direction. The buoyancy effects in terms of temperature and concentration differences are inserted in the

x

-momentum equation. The aspects of heat and mass transfer are studied using dimensionless thermophoresis, Schmidt and Brownian motion parameters. The governing coupled partial differential system (PDEs) is remodeled into coupled non-similar nonlinear PDEs by introducing non-similar transformations. The numerical analysis for the dimensionless non-similar partial differential system is performed using a local non-similarity method via bvp4c. Finally, the quantitative effects of emerging dimensionless quantities on the non-dimensional velocity, temperature and mass concentration in the boundary layer are conferred graphically, and inferences are drawn that important quantities of interest are substantially affected by these parameters. It is concluded that non-similar modeling, in contrast to similar models, is more general and more accurate in convection studies in the presence of buoyancy effects for second-grade non-Newtonian fluids.
GaSb-based type-I quantum well cascade diode lasers emitting at nearly 2-μm wavelength with digitally grown AlGaAsSb gradient layers*
Authors: Zhang Yi , Yang Cheng-Ao , Shang Jin-Ming , Chen Yi-Hang , Wang Tian-Fang , Zhang Yu , Xu Ying-Qiang , Liu Bing , Niu Zhi-Chuan
Published: February 2021

We report a GaSb-based type-I quantum well cascade diode laser emitting at nearly 2-μm wavelength. The recycling of carriers is realized by the gradient AlGaAsSb barrier and chirped GaSb/AlSb/InAs electron injector. The growth of quaternary digital alloy with a gradually changed composition by short-period superlattices is introduced in detail in this paper. And the quantum well cascade laser with 100-μm-wide, 2-mm-long ridge generates an about continuous-wave output of 0.8 W at room temperature. The characteristic temperature T
0 is estimated at above 60 K.
CO2emissions from karst cascade hydropower reservoirs: mechanisms and reservoir effect
Authors: Wang Wanfa , Li Si-Liang , Zhong Jun , Wang Lichun , Yang Hong , Xiao Huayun , Liu Cong-Qiang
Published: February 2021

Carbon dioxide (CO2) emissions from aquatic surface to the atmosphere has been recognized as a significant factor contributing to the global carbon budget and environmental change. The influence of river damming on the CO2emissions from reservoirs remains poorly constrained. This is hypothetically due to the change of hydraulic retention time (HRT) and thermal stratification intensity of reservoirs (related to the normal water level, NWL). To test this hypothesis, we quantified CO2fluxes and related parameters in eight karst reservoirs on the Wujiang River, Southwest China. Our results showed that there was a significant difference in the values ofpCO2(mean = 3205.7μatm, SD = 2183.4μatm) andδ13CCO2(mean = −18.9‰, SD = 1.6‰) in the cascade reservoirs, suggesting that multiple processes regulate CO2production. Moreover, the calculated CO2fluxes showed obvious spatiotemporal variations, ranging from −9.0 to 2269.3 mmol m−2d−1, with an average of 260.1 mmol m−2d−1. Interestingly, the CO2flux andδ13CCO2from reservoirs of this study and other reservoirs around the world had an exponential function with the reservoir effect index (Ri, HRT/NWL), suggesting the viability of our hypothesis on reservoir CO2emission. This empirical function will help to estimate CO2emissions from global reservoirs and provide theoretical support for reservoir regulation to mitigate carbon emission.