bluuebunny/crossref_metadata_2025 huggingface dataset:
Shopping tourism with a focus on the clothing industry in relation to globalization
Authors: Ric Tomáš , Šálková Daniela
Published: January 2021

Research background: The paper deals with the connections between international tourism and shopping, and therefore the purchase of clothing in relation to consumers. In the last few years, shopping has become one of the factors determining tourist’s decisions about choosing a travel destination. One-third of tourists have ever travelled just to buy clothes abroad. Such behaviour offers enormous economic potential for companies and the state economy. Shopping tourism is an integral part of globalization.

Purpose of the article: The article’s aim is to characterize the elements of consumer behaviour in the framework of shopping tourism when buying clothing products. In addition to consumer preferences, the aim is to characterize the main types of clothing products that travellers are interested in and the impact of this consumer behaviour on the globalization.

Methods: A questionnaire is compiled on the basis of stated hypotheses. The results will be evaluated using appropriate statistical methods such as the Kruskal-Wallis test, Spearman’s correlation coefficient and categorical principal components analysis.

Findings & Value added: Research has shown that the first group of preferred garments consists of local products at a higher price level produced in low quantity. The second type of product is low-cost garments produced at a high cost under conditions that do not correspond to the principles of sustainable development. The clothing industry impact on global sustainable development is largely negative. In this regard, we can talk about the negative impact of globalization. This is no different from tourism.
The Benefits of Applying the Green Purchasing
Authors: Slastanova Nikola , Palus Hubert , Sulek Rastislav , Parobek Jan , Slastanova Katarina
Published: January 2021

Research background: Globalisation brings both opportunities and challenges. It affects relationships in various areas of business, including the wood processing industry. The EU seeks to make the most of globalisation for citizens and businesses while reducing its negative effects. Green purchasing is one of the tools that helps to eliminate the negative effects of globalisation. To increase the competitiveness in the wood processing industry through green purchasing is not only about reducing the direct environmental impact of business activities but also about bringing social and health as well as economic and political benefits. Green purchasing is intelligent purchasing, which increases the efficiency of procurement of goods and services with the lowest possible negative impact on the environment and thus replaces goods or services that would be purchased by default to perform the same function but with a worse impact on the environment.

Purpose of the article: The aim of this paper is to determine the benefits of applying green purchasing in wood processing companies. By identifying the internal and external environment, it is possible to determine the benefits of green purchasing in terms of economic, environmental, political, and social and health aspects.

Methods: Using the methods of expert estimation, SWOT analysis and Fuller’s triangle, the paper evaluates the benefits of green purchasing, and defines appropriate measures with possible strategies for its application in the wood processing industry.

Findings & Value added: The main economic benefit is the reduced costs, social is the education of employees, and ecological benefit is the protection of forest resources.
Consumer Behaviour of Generation Z in the Context of Dual Quality of Daily Consumption Products on EU market
Authors: Šramková Marianna , Sirotiaková Mária
Published: January 2021

Research background: The paper focuses on the issue of dual quality of daily consumption products through the lens of the Z generation. Z generation is a generation of people born between years of 1997-2012, a generation that will become the main purchasing power in a few years.

Purpose of the article: The purpose of the research was to explore the possibility whether the information on dual product quality affects the consumer behaviour of members of Z generation and if so, to what extent and at what type of products.

Methods: Main method to receive necessary data for analyse was a questionnaire and its statistical evaluation given hypothesis. The research was carried out in the form of a survey consisted of 227 consumers.

Findings & Value added: The results show that 85% of them had dual quality information, perceived this issue as a serious problem, and the majority wants to be informed more about this issue. More than half of the Z generation had changed their consumer behaviour as a result of information about the dual quality of goods on market of European Union, especially women with higher education and the Z generation living in rural areas. Research confirmed that the change in behaviour mainly concerns non-food products such as cosmetics and clothing.
The Future of Work in a Jobless Society: Globalization, Smart Digitalization, and Cognitive Automation
Authors: Dijmărescu Irina , Ionescu Luminița
Published: January 2021

Research background: The future of work is undoubtedly one of the toughest challenges faced by many researchers and managers all over the word. The new era in digital globalization and smart digitalization, the trends in robotization and artificial intelligence have changed the labour market. Due to accelerated technology, many companies are ready to adopt digital solutions, stationary robots and drones with significant consequences over the declining jobs. The new human-machine frontier will determine a different outlook work in a jobless society, where many roles become automated, while human’s role in these processes is minimized.

Purpose of the article: In our opinion, globalization and impact of artificial intelligence on the future of work will be significant. In this paper we try to analyse and clarify the issues in question in terms of smart digitalization, cognitive automation, human-machine frontier and changing employment types. The data used for this research was obtained from previous study conducted by World Bank and OECD.

Methods: In order to fulfil our goal, we apply the methods of comparison, analysis, deduction and our estimates for identifying the trends that are shaping the future of jobs and the evolution of jobs caused by technological change.

Findings & Value added: In the near future, innovation will continue to accelerate and many artisan jobs are being lost to computerization and office automation. Finally, we formulate our own conclusion and view about digitalization and opportunities to create new jobs, increase productivity, and cost reduction, through innovation and accelerating change.
The Economics of Religion in a Globalizing World: Communist China and Post-Communist Central Europe
Authors: Minárik Pavol
Published: January 2021

Research background: Religion is often neglected by economists despite the existing studies of its importance for the economy. Religion and culture shape the development of informal and formal institutions and hence impact economic development. Considering the economic importance of China, the religious situation in that country deserves attention; at the same time, due to the peculiar conditions of religion under Communism, the future of religion in China seems rather unclear.

Purpose of the article: The paper proposes that the economics of religion may be useful in the analysis of the religious situation in China. It shows the possibilities of applying the economic approach even where markets are suppressed, such as under Communist rule. In light of economic theory, it shows that the experience of Central European countries under Communist rule, particularly Czechoslovakia, may provide clues about the future of religion in China.

Methods: The paper builds on previous findings in the economics of religion. It reviews the theories concerning the regulation of the religious markets and the effects of deregulation, as well as the theories specifically developed to analyze religion under heavy regelation and the strategies for its survival. The history of Communist China and Czechoslovakia are compared with regard to those theories.

Findings & Value added: The paper shows the similarities between Communist China and Czechoslovakia. The parallels seem useful to predict the further development of religion in China, including the effect of the possible tightening of anti-religious policies as well as those of deregulation upon the liberalization of the Chinese political regime.
Global Emergency Impact to Latvian Micro and Small Enterprises
Authors: Riekstina Iluta , Zvirgzdina Rosita
Published: January 2021

Research background:2020 will always remain a pandemic year in the world. A year that shook everyone including business. After the end of the emergency, many countries are planning business recovery measures. Many programs are planned for micro and small businesses. Due to the large number of micro-enterprises that the authors decided to conduct a study on the preparedness of micro and small enterprises for emergencies. About the areas in which small businesses operate, how and whether they are only able to operate in the domestic market or are ready for globalization. 65% of Latvian micro and small enterprises in surveys conducted by credit institutions showed that the impact of COVID19 on operations is noticeable and will be necessary for business recovery. At the same time, 47% of them confirmed that they plan to change their business model according to the new situation.

Purpose of the article:The aim of the research is to identify the interaction of the activity structure of Latvian micro and small enterprises with emergency situations. To analyze the operating environment and the intensity of its impact on business.

Methods:Quantitative research is based on official business data from several sources - Enterprise Register, Ministry of Economics, Re-Identifier of the Register of Enterprises Ltd. “Lursoft”, Central Statistical Bureau. The study will review data on the last 5 years by analyzing data for 2013-2017. The following research methods have been used for the research: quantitative data research approach, analytical study comparing data for five years and graphical method - visualization and analysis of visual information.

Findings & Value added: As a result of the article, it is planned to group the directions of activities of micro and small enterprises based on the impact of the emergency situation on them. Thus, performing an analysis of the readiness of Latvian micro and small enterprises for emergency situations and the impact on operations.
Gender equality management in modern company management in era of globalization
Authors: Sukalova Viera , Ceniga Pavel
Published: January 2021

Research background: Today’s dynamic times in era of globalization bring change to all areas of business; there is increasing pressure to increase the competitiveness of companies and thus increase the requirements for management. Despite current trends, emancipation and globalization, the issue of gender equality and gender policy is still relevant and needs to be addressed. New management disciplines include diversity management. It focuses on the different social and cultural identities of employees and also on eliminating discrimination and inequality in the organization. Diversity management has later developed into a relatively separate discipline - gender relations management. Label recognition of the organization as “gender-integrated” means that organizational culture and processes are based on the recognition and promotion of gender equality. Gender equality is associated with the concept of equal opportunities at work and actual legislation in the field of labour protection.

Purpose of the article: The aim of the paper is based on modern management trends and the legislative framework for gender equality as well as anti-discrimination management principles to analyse the current situation on the example of a case study from the requirements of a gender integrated organization and to propose systemic measures to address issues for business practice.

Methods: The method of analysis, synthesis, deduction, interview and questionnaire was used in the research. A survey was performed in 2019 on the examle of case study in big sized company in the field of machinery industry.

Findings & Value added: Adherence to gender equality policy can be a competitive advantage for the entrepreneur. This initiative is becoming a motivating factor for entrepreneurs to launch measures that would lead to introduction and strengthening of gender equality.
How do Slovak Women Perceive Their Opportunities on the Global Labor Market? Generational study
Authors: Urbánová Mária , Kozáková Jana , Klátiková Silvia
Published: January 2021

Research background:Despite European labor market offers wider opportunities of employment also for Slovak women, it is characterized by notable gender disparities too. Except for the 12% employment gap, the 16% wage gap still occurs. Study examines generational differences in attitudes of Slovak woman according to their opportunities on the global labor market with the respect of fact that, women’s own views on the need for such activities differ across generations.

Purpose of the article:The aim is to point out that views of Slovak women on their opportunities at the global labor market is perceived differently by women of diverse generations.

Methods:The research was conducted using the questionnaire method on a sample of 361 respondents, who were exclusively women of economically active age already incorporated in the labor market. For this reason, stratified randomization was performed and members of Generations X, Generation Y, and Generation Z were approached to participate in the online survey. The assumptions of differences were set for 6 chosen variables and statistically tested according to the age through Kruskal-Wallis test using XL stat. As a post hoc test the Bonferroni correction was computed to counteract the problem of multiple comparisons between variables.

Findings & Value added: The uniqueness of our study is primarily in targeting at women of different generations and looking for differences in their generational attitudes.
The Dependence of the CZK Exchange Rate on the Development of the GDP in the Czech Republic in the Conditions of an Expected Crisis
Authors: Machová Veronika , Krulický Tomáš
Published: January 2021

Research background: In the past, some studies proved that the development of a currency exchange rate predicts the development of the whole national economy. The monetary market overtakes the development of the actual economy for a few months. Does this apply also in the case of the Czech koruna, in the era of the global Coronavirus pandemics and in the world affected by the pandemics?

Purpose of the article: The main objective is to analyze a dependence of the Czech koruna (CZK) to Euro (EUR) exchange rate development on gross domestic product of the Czech Republic in the conditions of an expected crisis.

Methods: The data used of the analysis are represented by the information about the CZK and EUR exchange rate from the beginning of 1999 to the 15th June 2020 and by the quarterly development of the Czech GDP. To measure the dependence and predict the development of the GDP based on the CZK exchange rate development, the method of AI is used, namely the regression analysis using the artificial neural networks.

Findings & Value added: The effect of EUR/CZK on GDP can be quantified reaching around 31%. It is assumed that the GDP will fall significantly in 2020 with a certain growth only being possibly expected in 2021 (even more significantly in the second quarter of 2021). Due to the GDP development, the development of the EUR/CZK could then be forecasted as well.
Increasing the Efficiency of the Fiscal System – a Parallel between Poland and Romania
Authors: Rădulescu Carmen Valentina , Bodislav Dumitru Alexandru , Negescu Oancea Diana Mihaela
Published: January 2021

Research background: This paper presents an overview and a fundamental analysis of the fiscal system in Romania and how it should be, also by showing one of the European champions on fiscal efficiency, the Polish system. Although we are talking about the 21st century, about evolution, economic, financial and fiscal sustainability, the Romanian tax system has been intensely blamed for its inefficiency, outdated procedures and last but not least the excessive bureaucracy. This topic was intensely discussed and debated both by the competent authorities who tried to identify the deepest issues and by the specialized press representing a great interest for both natural and legal taxpayers.

Purpose of the article: The purpose of this paper is to identify the challenges, limits and solutions so that the Romanian tax system can become efficient and implicit, a model to follow for success. The paper shows how the Romanian fiscal system works and how taxes add to the degree of economic growth and what are the limits of actual system.

Methods: The paper evaluates the actual literature, its conceptual limits, the classification and how it should be at technical level.

Findings & Value added: The research will highlight the harmonization of the Romanian fiscal system with the European Union’s one and especially with one of its champions, Poland.
The Willingness to Devote Time to Volunteers Projects in Relation to Volunteers Practice
Authors: Zárubová Lucie , Švecová Lenka
Published: January 2021

Research background: The article deals with the volunteering. The relationship between school and volunteer orientation is compared among respondents preparing for the future labour market, i.e. high school and university students of various specializations who study in the Czech Republic. Students can be motivated by gaining experience in team cooperation in solving a common goal like one type of the motivator. Are volunteers and potential volunteers willing to devote their time to projects in the same way, whether they have experience with volunteering or not?

Purpose of the article: The purpose is to find the connection between the age of the respondents, their experiences with volunteering and the time they are willing to devote to the volunteering.

Methods: The method is quantitative study of answers of students from high school and university students. The quantitative study uses Chi square test. The result of quantitative elaboration of the questionnaire survey is the answer to whether there is a connection between the age of the respondents, their experience with volunteering and the time which they are willing to devote to the volunteering.

Findings & Value added: The result finds the differences and connections between age of volunteers, their experiences with volunteering and with willingness to be the volunteer for longer or shorter time. The result of the survey brings benefits to managers to recruit volunteers and it cannot be denied that the willingness of volunteers to devote their time to volunteering will change as they gain the experience.
Transcranial Stimulation Improves Volume and Perceived Exertion but does not Change Power
Authors: Fortes Leonardo de Sousa , Mazini-Filho Mauro , Lima-Júnior Daltonde , Machado Daniel Gomes Silva , Albuquerque Maicon Rodrigues , Fonseca Fabiano de Souza , Ferreira Maria Elisa Caputo
Published: January 2021

This study aimed to analyze the acute effect of anodal transcranial direct current stimulation (a-tDCS) over the primary motor cortex (M1) on the volume, perceived exertion, and neuromuscular performance measurements in trained and untrained adults. Twenty-four male adults (12 trained and 12 untrained) participated in this single-blind, randomized, and sham-controlled study. The participants performed three back squat repetitions using the 15RM load with maximal concentric velocity to assess neuromuscular performance before tDCS and 30-min after resistance exercise. Next, they were randomly assigned to a-tDCS over M1 or the sham condition. Participants performed ten sets of parallel back squat with 15RM load and repetitions sustained to momentary muscular failure. The total number of repetitions was higher (p<0.05) and perceived exertion was lower (p<0.05) after a-tDCS in both groups. Peak power, velocity, and force decreased in both groups after the RE session (p<0.05), but with a higher rate in untrained individuals (p<0.05). No significant effect was found for peak power, peak velocity, and peak force (p>0.05). This study suggests that using a-tDCS may improve the total volume of repetitions and perceived exertion in trained and untrained individuals.
Cardiovascular Responses to Muscle Stretching: A Systematic Review and Meta-analysis
Authors: Thomas Ewan , Bellafiore Marianna , Gentile Ambra , Paoli Antonio , Palma Antonio , Bianco Antonino
Published: January 2021

The aim of this study will be to review the current body of literature to understand the effects of stretching on the responses of the cardiovascular system. A literature search was performed using the following databases: Scopus, NLM Pubmed and ScienceDirect. Studies regarding the effects of stretching on responses of the cardiovascular system were investigated. Outcomes regarded heart rate(HR), blood pressure, pulse wave velocity (PWV of which baPWV for brachial-ankle and cfPWV for carotid-femoral waveforms), heart rate variability and endothelial vascular function. Subsequently, the effects of each outcome were quantitatively synthetized using meta-analytic synthesis with random-effect models. A total of 16 studies were considered eligible and included in the quantitative synthesis. Groups were also stratified according to cross-sectional or longitudinal stretching interventions. Quality assessment through the NHLBI tools observed a “fair-to-good” quality of the studies. The meta-analytic synthesis showed a significant effect of d=0.38 concerning HR, d=2.04 regarding baPWV and d=0.46 for cfPWV. Stretching significantly reduces arterial stiffness and HR. The qualitative description of the studies was also supported by the meta-analytic synthesis. No adverse effects were reported, after stretching, in patients affected by cardiovascular disease on blood pressure. There is a lack of studies regarding vascular adaptations to stretching.
Transpancreatic biliary sphincterotomy versus double guidewire in difficult biliary cannulation: a randomized controlled trial
Authors: Kylänpää Leena , Koskensalo Vilja , Saarela Arto , Ejstrud Per , Udd Marianne , Lindström Outi , Rainio Mia , Tenca Andrea , Halttunen Jorma , Qvigstad Gunnar , Arnelo Urban , Fagerström Niklas , Hauge Truls , Aabakken Lars , Grönroos Juha
Published: January 2021

Background Difficult biliary cannulation in endoscopic retrograde cholangiopancreatography (ERCP) increases the risk of post-ERCP pancreatitis (PEP). The purpose of this prospective, randomized, multicenter study was to compare two advanced rescue methods, transpancreatic biliary sphincterotomy (TPBS) and a double-guidewire (DGW) technique, in difficult common bile duct (CBD) cannulation.

Methods Patients with native papilla and planned CBD cannulation were recruited at eight Scandinavian hospitals. An experienced endoscopist attempted CBD cannulation with wire-guided cannulation. If the procedure fulfilled the definition of difficult cannulation and a guidewire entered the pancreatic duct, randomization to either TPBS or to DGW was performed. If the randomized method failed, any method available was performed. The primary end point was the frequency of PEP and the secondary end points included successful cannulation with the randomized method.

Results In total, 1190 patients were recruited and 203 (17.1 %) were randomized according to the study protocol (TPBS 104 and DGW 99). PEP developed in 14/104 patients (13.5 %) in the TPBS group and 16/99 patients (16.2 %) in the DGW group (P = 0.69). No difference existed in PEP severity between the groups. The rate of successful deep biliary cannulation was significantly higher with TPBS (84.6 % [88/104]) than with DGW (69.7 % [69/99]; P = 0.01).

Conclusions In difficult biliary cannulation, there was no difference in PEP rate between TPBS and DGW techniques. TPBS is a good alternative in cases of difficult cannulation when the guidewire is in the pancreatic duct.
Development and Prospective Validation of the Levothyroxine Dose
Prediction Model in Primary Hypothyroidism
Authors: Singh Rekha , Tandon Ashwani , Awasthi Ashish
Published: January 2021

Multiple visits are needed to achieve euthyroidism on levothyroxine in newly
detected primary hypothyroidism. We aimed to develop a levothyroxine dose
estimation algorithm for primary hypothyroidism. Adults with newly diagnosed
hypothyroidism were enrolled prospectively, first in the training cohort,
followed by the validation cohort separated by time and person. We developed
a predictive algorithm from Training Cohort and validated the model in
Validation Cohort. Training Cohort: In this cohort, 358 subjects (259 women
and 99 men) were enrolled. The median duration needed to achieve
euthyroidism was 4±0.5 months. The mean levothyroxine daily dose was
60.5±34.1 μg. Data of euthyroid subjects within 6
months of treatment initiation and age range 18–65 years were used
for algorithm development. In the multivariable linear regression algorithm,
pretreatment serum thyrotropin level, and sex formed the best-fit predictive
model (adjusted R2 0.73, p-value <0.001). Validation
Cohort: Eighty-four subjects (61 women and 23 men) were enrolled and started
on an estimated levothyroxine dose derived from the developed prediction
model. On the first follow-up on treatment, 34/50 participants
achieved euthyroidism (68%) at 1.5 months. In conclusion, the
proposed prediction model for levothyroxine dose estimation effectively
achieves early euthyroidism in two-third subjects in the age range of
18–65 years.
Pronounced Ptosis in Myasthenia Gravis—A New Bedside Clinical Sign
Authors: Vinny Pulikottil W. , Vishnu Venugopalan Y.
Published: January 2021

We report three cases of myasthenia gravis in whom the asymmetrical ptosis at presentation became more pronounced with the described bedside technique. Pronounced ptosis could be elicited by making the patient speak continuously for up to 2 minutes. Pauses for breathing and natural blinking were allowed. The sign is best elicited in newly diagnosed and treatment-naive patients. The loss of compensation for ptosis by frontalis muscle due to speech-induced fatigue may be responsible for the observed effect. Patients’ symptoms abated on treatment with acetylcholine esterase inhibitors, steroids, and steroid-sparing agents.
Risk of Early Birth among Women with a Urinary Tract Infection: A Retrospective Cohort Study
Authors: Baer Rebecca J. , Nidey Nichole , Bandoli Gretchen , Chambers Brittany D. , Chambers Christina D. , Feuer Sky , Karasek Deborah , Oltman Scott P. , Rand Larry , Ryckman Kelli K. , Jelliffe-Pawlowski Laura L.
Published: January 2021

Objective The aim of the study is to evaluate the risk of preterm birth (PTB, <37 weeks) and early term (37 and 38 weeks) birth among women with an emergency department (ED) visit or hospitalization with a urinary tract infection (UTI) by trimester of pregnancy.

Methods The primary sample was selected from births in California between 2011 and 2017. UTIs were identified from the ED or hospital discharge records. Risk of PTB, by subtype, and early term birth were evaluated by trimester of pregnancy and by type of visit using log-linear regression. Risk ratios were adjusted for maternal factors. Antibiotic usage was examined in a population of privately insured women from Iowa.

Results Women with a UTI during pregnancy were at elevated risk of a birth <32 weeks, 32 to 36 weeks, and 37 to 38 weeks (adjusted risk ratios [aRRs] 1.1–1.4). Of the women with a diagnostic code for multiple bacterial species, 28.8% had a PTB. A UTI diagnosis elevated risk of PTB regardless of antibiotic treatment (aRR 1.4 for treated, aRR 1.5 for untreated).

Conclusion UTIs are associated with early birth. This association is present regardless of the trimester of pregnancy, type of PTB, and antibiotic treatment.
Malnutrition Essentials for Neurologists and Neurosurgeons: A Review of the Literature
Authors: Tahta Alican , Turgut Yasar B. , Sahin Cem
Published: January 2021

Malnutrition still causes deaths in the world today and protein energy malnutrition (PEM) is characterized by increased oxidative stress, immune deficiency, and development of various infections. Even today, however, it is an underrecognized and undertreated entity in neurology and neurosurgery. In this article, we therefore seek to review the available literature regarding various factors affecting surgical outcome of children with malnutrition undergoing some neurosurgical interventions including shunt surgery and traumatic brain injury in intensive care unit, in addition to its effects upon oxidative stress status and immunity. Furthermore, we attempt to provide essential knowledge of malnutrition affecting surgical outcome of patients with PEM. Based on available evidence in the published literature, it is concluded that it is a serious public health problem characterized by increased oxidative stress, immune deficiency, and development of various infections.
Low frequency 1/f noise in deep submicrometer-sized magnetic tunnel junctions
Authors: Anh Nguyen T. N. , Pham Q. N. , Fukumoto M. , Goto M. , Okuno R. , Tomita H. , Kubota H. , Fukushima A. , Yakushiji K. , Watakabe T. , Hasebe S. , Lam D. D. , Do K. T. , Nguyen T. H. , Vu H. K. , Vu D. L. , Suzuki Y.
Published: January 2021

Magnetic tunnel junctions (MTJs) have been identified as promising candidates for the development of high-performance, ultra-low field magnetometers due to their high sensitivity, low cost, low power consumption, and small size. However, 1/f noise is often quite large at low frequencies and inevitably becomes one of the most difficult issues in developing a magnetic field sensor with ultrahigh sensitivity. Low-frequency 1/f noise can have both electric and magnetic origins, and it is a result of complex non-linear interactions between many degrees of freedom inside a sensor. Therefore, a reduction of the 1/f noise can be expected for the magnetic sensor with very small dimensions. Here, the dependence of the 1/f noise on voltage and strong hard-axis bias field in deep submicrometer-sized MgO-based MTJs is investigated with various junction sizes. The noise spectra were measured by using a home-built low-frequency noise measurement setup with maximum frequency up to 30 kHz. We find that the noise spectral power density is 1/f-like at low frequencies. The experimental results suggest a relative reduction of 1/f noise with respect to the intrinsic thermal noise in small-sized MTJs. The results may open a new approach for reducing the 1/f noise level in MTJ nanosensors.
Quantum transition probabilities due to overlapping electromagnetic pulses: Persistent differences between Dirac’s form and nonadiabatic perturbation theory
Authors: Mandal Anirban , Hunt Katharine L. C.
Published: January 2021

The probability of transition to an excited state of a quantum system in a time-dependent electromagnetic field determines the energy uptake from the field. The standard expression for the transition probability has been given by Dirac. Landau and Lifshitz suggested, instead, that the adiabatic effects of a perturbation should be excluded from the transition probability, leaving an expression in terms of the nonadiabatic response. In our previous work, we have found that these two approaches yield different results while a perturbing field is acting on the system. Here, we prove, for the first time, that differences between the two approaches may persist after the perturbing fields have been completely turned off. We have designed a pair of overlapping pulses in order to establish the possibility of lasting differences, in a case with dephasing. Our work goes beyond the analysis presented by Landau and Lifshitz, since they considered only linear response and required that a constant perturbation must remain as t → ∞. First, a “plateau” pulse populates an excited rotational state and produces coherences between the ground and excited states. Then, an infrared pulse acts while the electric field of the first pulse is constant, but after dephasing has occurred. The nonadiabatic perturbation theory permits dephasing, but dephasing of the perturbed part of the wave function cannot occur within Dirac’s method. When the frequencies in both pulses are on resonance, the lasting differences in the calculated transition probabilities may exceed 35%. The predicted differences are larger for off-resonant perturbations.
Germanene/2D-AlP van der Waals heterostructure: Tunable structural and electronic properties
Authors: Mojumder Md. Rayid Hasan , Islam Md. Sherajul , Park Jeongwon
Published: January 2021

Developing van der Waals heterostructures (vdWHs) utilizing vertical mounting of diverse two-dimensional (2D) materials is an efficient way of achieving favorable characteristics. Using first-principles calculations, we demonstrated the geometric configurations and electronic properties of germanene/2D-AlP vdWHs. We considered four high symmetric patterns that show a bandgap opening in the heterostructures of 200 meV–460 meV. The incorporation of spin-orbital coupling reduces the bandgap by 20 meV–90 meV. Both direct and indirect bandgaps were found from these high symmetric patterns, depending on the structural patterns. The charge density distribution and the partial density of states confirmed that germanene was the property builder of the heterostructure, in which 2D-AlP could be a decent substrate. The heterostructure bandgap can be widely tuned in the range 0 meV–500 meV by changing the interlayer separation between the two monolayers. The application of strain and external electric fields also significantly tailored the electronic structures of the heterostructures. Intriguingly, an exceptionally high carrier mobility of more than 1.5 × 105 cm2 V−1 s−1 was observed, which outperforms compared to other studies on germanene heterostructures. All these promising properties make the germanene/2D-AlP heterostructure a viable candidate for FETs, strain sensors, nanoelectronics, and spintronic devices.
Tuning charge transfer and recombination in exTTF/CNT nanohybrids by choice of chalcogen: A time-domain density functional analysis
Authors: Sarkar Ritabrata , Habib Md , Pal Sougata , Prezhdo Oleg V.
Published: January 2021

Supramolecular nanohybrids composed of carbon nanotubes (CNTs) and organic molecules are appealing candidates for many applications. We investigate charge separation and recombination dynamics in extended tetrathiafulvalene (exTTF), a well-known sulfur (S)-rich electron donor, immobilized on a CNT surface, and study the role of the chalcogen atom by comparing with the selenium (Se)-rich tetraselenafulvalene (exTSeF) analog. Using real-time time-dependent tight-binding density-functional theory combined with nonadiabatic molecular dynamics, we show that photo-excitation of exTTF results in electron transfer (ET) into the CNT conduction band, while CNT excitation leads to hole transfer (HT) to exTTF. The ET is sub-picosecond in both systems, while the HT transfer time depends strongly on the chalcogen. The simulated ET times agree with available experiments. HT from the excited CNT is accelerated by two orders of magnitude more in exTSeF/CNT than exTTF/CNT, because of smaller energy gap, larger nonadiabatic charge–phonon coupling, and longer coherence time. In comparison, nonradiative decay of the charge-separated state takes place on nanosecond time scales. Electrons and holes recombine more slowly by an order of magnitude in the exTTF/CNT hybrid because of weaker nonadiabatic coupling and shorter coherence time. The coupling is weaker since high frequency phonons are less active. The coherence is shorter due to participation of a broader spectrum of low-frequency modes. The state-of-the-art atomistic quantum dynamics simulation demonstrates the strong influence of the chalcogen atom on the separation and recombination dynamics of photo-generated carriers in the molecule/CNT hybrids. The insights provide valuable guidelines for optimization of photovoltaic efficiency in modern nanoscale materials.
Gas mixture flow, diffusion, and heat transfer in a long tube at moderately small Knudsen numbers
Authors: Zhdanov V. M. , Zaznoba V. A. , Stepanenko A. A.
Published: January 2021

The binary gas mixture flow, diffusion, and heat transfer through a long tube in the near-continuum regime (moderately small Knudsen numbers) are analyzed. The system of linearized third-order moment equations, obtained by Grad’s method, is used. An expression for the total mass flux of a binary gas mixture is deduced by using the extension of the procedure, proposed in the work by Zhdanov [“Slip and barodiffusion phenomena in slow flows of a gas mixture,” Phys. Rev. E 95, 033106 (2017)] for the study of slip phenomena in slow flows of a gas mixture. Relations for diffusion and heat fluxes are determined from the initial system of moment equations, averaged over the channel cross section, and supplied with several moments of the distribution function at the channel wall found with the modified Maxwell method. Analytical formulas for kinetic coefficients of the Onsager matrix, which connect averaged fluxes and gradients of the corresponding thermodynamic quantities, are obtained. It is shown that the employed approach automatically ensures the validity of the reciprocal relations for the cross terms in the Onsager matrix. The results of calculations of the derived kinetic coefficients for several binary mixtures of noble gases (He–Ar, Ne–Ar, and He–Xe) are presented and compared with numerical data found by the discrete velocity method on the basis of the linearized Boltzmann equation with the McCormack model.
Vertical p-type GaN Schottky barrier diodes with nearly ideal thermionic emission characteristics
Authors: Ueno Kohei , Shibahara Keita , Kobayashi Atsushi , Fujioka Hiroshi
Published: January 2021

We demonstrate herein the fabrication and operation of p-type GaN Schottky barrier diodes (SBDs) with nearly ideal rectifying characteristics using vertical bottom tunneling junction contacts. The interface between Ni and p-type GaN provides a large Schottky barrier height of 2.29 eV, which is promising for high-temperature operations. The vertical p-type GaN SBDs show nearly ideal rectifying characteristics with an ideality factor close to unity and a rectifying ratio as high as 106, even at 600 K. This distinguished performance indicates the superiority of p-type GaN SBDs for electron devices operated under high-temperature environments.
Autoignition and detonation development induced by temperature gradient in n-C7H16/air/H2O mixtures
Authors: Yu Zhou , Zhang Huangwei , Dai Peng
Published: January 2021

The effects of water vapor dilution on autoignition and detonation development induced by an ignition spot with thermal non-uniformity in an n-C7H16/air mixture are numerically investigated. Zero-dimensional homogeneous ignition under constant-volume conditions is studied first. It is found that excitation time increases, whereas total heat release decreases with a H2O vapor mole fraction. Moreover, the role of H2O vapor diluents as a third body considerably influences the critical temperature gradient. One-dimensional autoignition and detonation development caused by temperature gradients in ignition spots is then studied. Three different autoignition modes are identified: (I) supersonic deflagrative wave, (II) detonative wave, and (III) subsonic deflagrative wave. It is found that H2O dilution has a slightly better performance on detonation suppression than CO2 dilution. The chemistry–acoustics interactions during autoignition development are weakened when the H2O mole fraction is increased. Besides, H2O vapor dilution can delay the detonation initiation and reduce detonation intensity. Furthermore, typical autoignition processes induced by a hotspot and the chemical effects of water vapor diluent are discussed. It is seen that the chemical effects of H2O dilution do not affect the lower limits of detonation development curves. Besides, the third body effect from the H2O vapor diluent is important in suppressing the detonation development for the investigated ignition spot size. Finally, the effects of equivalence ratios and ignition spot sizes on the autoignition modes of n-C7H16/air/H2O mixtures are studied. It is observed that the water vapor diluted mixtures with the fuel-lean condition are advantageous in inhibiting detonation from localized thermal non-uniformity.
The SIRPα–CD47 immune checkpoint in NK cells
Authors: Deuse Tobias , Hu Xiaomeng , Agbor-Enoh Sean , Jang Moon K. , Alawi Malik , Saygi Ceren , Gravina Alessia , Tediashvili Grigol , Nguyen Vinh Q. , Liu Yuan , Valantine Hannah , Lanier Lewis L. , Schrepfer Sonja
Published: January 2021

Here we report on the existence and functionality of the immune checkpoint signal regulatory protein α (SIRPα) in NK cells and describe how it can be modulated for cell therapy. NK cell SIRPα is up-regulated upon IL-2 stimulation, interacts with target cell CD47 in a threshold-dependent manner, and counters other stimulatory signals, including IL-2, CD16, or NKG2D. Elevated expression of CD47 protected K562 tumor cells and mouse and human MHC class I–deficient target cells against SIRPα+ primary NK cells, but not against SIRPα− NKL or NK92 cells. SIRPα deficiency or antibody blockade increased the killing capacity of NK cells. Overexpression of rhesus monkey CD47 in human MHC-deficient cells prevented cytotoxicity by rhesus NK cells in a xenogeneic setting. The SIRPα–CD47 axis was found to be highly species specific. Together, the results demonstrate that disruption of the SIRPα–CD47 immune checkpoint may augment NK cell antitumor responses and that elevated expression of CD47 may prevent NK cell–mediated killing of allogeneic and xenogeneic tissues.
Proteomic and functional mapping of cardiac NaV1.5 channel phosphorylation sites
Authors: Lorenzini Maxime , Burel Sophie , Lesage Adrien , Wagner Emily , Charrière Camille , Chevillard Pierre-Marie , Evrard Bérangère , Maloney Dan , Ruff Kiersten M. , Pappu Rohit V. , Wagner Stefan , Nerbonne Jeanne M. , Silva Jonathan R. , Townsend R. Reid , Maier Lars S. , Marionneau Céline
Published: January 2021

Phosphorylation of the voltage-gated Na+ (NaV) channel NaV1.5 regulates cardiac excitability, yet the phosphorylation sites regulating its function and the underlying mechanisms remain largely unknown. Using a systematic, quantitative phosphoproteomic approach, we analyzed NaV1.5 channel complexes purified from nonfailing and failing mouse left ventricles, and we identified 42 phosphorylation sites on NaV1.5. Most sites are clustered, and three of these clusters are highly phosphorylated. Analyses of phosphosilent and phosphomimetic NaV1.5 mutants revealed the roles of three phosphosites in regulating NaV1.5 channel expression and gating. The phosphorylated serines S664 and S667 regulate the voltage dependence of channel activation in a cumulative manner, whereas the nearby S671, the phosphorylation of which is increased in failing hearts, regulates cell surface NaV1.5 expression and peak Na+ current. No additional roles could be assigned to the other clusters of phosphosites. Taken together, our results demonstrate that ventricular NaV1.5 is highly phosphorylated and that the phosphorylation-dependent regulation of NaV1.5 channels is highly complex, site specific, and dynamic.
Rashba coupling and spin switching through surface states of Dirac semimetals
Authors: Baba Yuriko , Domínguez-Adame Francisco , Platero Gloria , Molina Rafael A
Published: January 2021

We study the effect of the Rashba spin–orbit coupling on the Fermi arcs of topological Dirac semimetals. The Rashba coupling is induced by breaking the inversion symmetry at the surface. Remarkably, this coupling could be enhanced by the interaction with the substrate and controlled by an external electric field. We study analytically and numerically the rotation of the spin of the surface states as a function of the electron’s momentum and the coupling strength. Furthermore, a detailed analysis of the spin-dependent two-terminal conductance is presented in the clean limit and with the addition of a random distribution of impurities. Depending on the magnitude of the quadratic terms in the Hamiltonian, the spin-flip conductance may become dominant, thus showing the potential of the system for spintronic applications, since the effect is robust even in the presence of disorder.
Tunable bandpass plasmonic filter based on graphene as the nonlinear Kerr material
Authors: Kokabi Mohsen , Ghorbani Saeed , Moayed Seyed Hossein
Published: January 2021

In this paper, a band-pass plasmonic filter is introduced based on metal–insulator–metal waveguide coupled with two narrow slabs. Our reported plasmonic structure is investigated using the numerical solution of finite element method. The filter performance is analyzed for two cases of linear and nonlinear. The selected Kerr nonlinear material is a single graphene layer. The simulation results show that, we can tune the resonant wavelength by considering the Kerr effect of the graphene layer, performance and by adjusting the incident light signal without changing the physical characteristics of the structure. The simplicity of the structure and a compact size are the advantages of the proposed nonlinear plasmonic filter which make that suitable to design the integrated all-optical circuits.
Generating multi-layer nested chaotic attractor and its FPGA implementation*
Authors: Peng Xuenan , Zeng Yicheng , Wang Mengjiao , Li Zhijun
Published: January 2021

Complex chaotic sequences are widely employed in real world, so obtaining more complex sequences have received highly interest. For enhancing the complexity of chaotic sequences, a common approach is increasing the scroll-number of attractors. In this paper, a novel method to control system for generating multi-layer nested chaotic attractors is proposed. At first, a piecewise (PW) function, namely quadratic staircase function, is designed. Unlike pulse signals, each level-logic of this function is square constant, and it is easy to realize. Then, by introducing the PW functions to a modified Chua’s system with cubic nonlinear terms, the system can generate multi-layer nested Chua’s attractors. The dynamical properties of the system are numerically investigated. Finally, the hardware implementation of the chaotic system is used FPGA chip. Experimental results show that theoretical analysis and numerical simulation are right. This chaotic oscillator consuming low power and utilization less resources is suitable for real applications.
Fractal sorting vector-based least significant bit chaotic permutation for image encryption*
Authors: Xian Yong-Jin , Wang Xing-Yuan , Zhang Ying-Qian , Wang Xiao-Yu , Du Xiao-Hui
Published: January 2021

The image’s least significant bit (LSB) covers lots of the details that have been commonly used in image encryption analysis. The newly proposed fractal sorting vector (FSV) and FSV-based LSB chaotic permutation (FSV-LSBCP) is a novel chaotic image encryption cryptosystem introduced in this article. The FSV-LSBCP effectively strengthens the security of the cryptographic scheme concerning the properties of the FSV. Key analysis, statistical analysis, resistance differential attack analysis, and resistance to cropping attacks and noise attacks are the focus of the suggested image encryption cryptosystem. The security experiment shows that the cryptosystem is adequate to achieve the desired degree of security.
A rigidity theorem for Killing vector fields on compact manifolds with almost nonpositive Ricci curvature
Authors: Katsuda Atsushi , Nakamura Takuya
Published: January 2021

We prove a rigidity theorem for Killing vector fields of a manifold with almost nonpositive Ricci curvature, which is a generalization of Bochner’s classical results.