447 research outputs found
Evaluating the suitability of several AR devices and tools for industrial applications
In recent years, there has been an increasing interest in Industrial Augmented Reality (IAR) due to its prominent role in the ongoing revolution known as Industry 4.0. For companies and industries it is essential to evaluate carefully which of the developed AR-based technologies to adopt, and when, for tasks such as training, maintenance, assistance, and collaborative design. There is also a wide array of hardware and software alternatives on the market, characterized by a significant heterogeneity in terms of functionalities, performance and cost. With this work, our objective is to study and compare some widely available devices and Software Development Kits (SDKs) for AR by leveraging a set of evaluation criteria derived from the actual literature which have been deemed capable to qualify the above assets as suitable for industrial applications. Such criteria include the operative range, robustness, accuracy and stability. Both marker-based and marker-less solutions have been considered, in order to investigate a wide range of possible use cases
Comparison of structural transformations and superconductivity in compressed Sulfur and Selenium
Density-functional calculations are presented for high-pressure structural
phases of S and Se. The structural phase diagrams, phonon spectra,
electron-phonon coupling, and superconducting properties of the isovalent
elements are compared. We find that with increasing pressure, Se adopts a
sequence of ever more closely packed structures (beta-Po, bcc, fcc), while S
favors more open structures (beta-Po, simple cubic, bcc). These differences are
shown to be attributable to differences in the S and Se core states. All the
compressed phases of S and Se considered are calculated to have weak to
moderate electron-phonon coupling strengths consistent with superconducting
transition temperatures in the range of 1 to 20 K. Our results compare well
with experimental data on the beta-Po --> bcc transition pressure in Se and on
the superconducting transition temperature in beta-Po S. Further experiments
are suggested to search for the other structural phases predicted at higher
pressures and to test theoretical results on the electron-phonon interaction
and superconducting properties
Direct Regulation of CLOCK Expression by REV-ERB
Circadian rhythms are regulated at the cellular level by transcriptional feedback loops leading to oscillations in expression of key proteins including CLOCK, BMAL1, PERIOD (PER), and CRYPTOCHROME (CRY). The CLOCK and BMAL1 proteins are members of the bHLH class of transcription factors and form a heterodimer that regulates the expression of the PER and CRY genes. The nuclear receptor REV-ERBα plays a key role in regulation of oscillations in BMAL1 expression by directly binding to the BMAL1 promoter and suppressing its expression at certain times of day when REV-ERBα expression levels are elevated. We recently demonstrated that REV-ERBα also regulates the expression of NPAS2, a heterodimer partner of BMAL1. Here, we show that REV-ERBα also regulates the expression another heterodimer partner of BMAL1, CLOCK. We identified a REV-ERBα binding site within the 1st intron of the CLOCK gene using a chromatin immunoprecipitation – microarray screen. Suppression of REV-ERBα expression resulted in elevated CLOCK mRNA expression consistent with REV-ERBα's role as a transcriptional repressor. A REV-ERB response element (RevRE) was identified within this region of the CLOCK gene and was conserved between humans and mice. Additionally, the CLOCK RevRE conferred REV-ERB responsiveness to a heterologous reporter gene. Our data suggests that REV-ERBα plays a dual role in regulation of the activity of the BMAL1/CLOCK heterodimer by regulation of expression of both the BMAL1 and CLOCK genes
Workplace Accidents among Nepali Male Workers in the Middle East and Malaysia: A Qualitative Study
There are many Nepali men working in the Middle East and Malaysia and media reports and anecdotal evidence suggest a high risk of workplace-related accidents and injuries for male Nepali workers. Therefore, this study aims to explore the personal experiences of male Nepali migrants of unintentional injuries at their place of work. In-depth, face-to-face interviews (n = 20) were conducted with male Nepali migrant workers. Study participants were approached at Kathmandu International Airport, hotels and lodges around the airport. Interviews were transcribed and analysed using thematic analysis. Almost half of study participants experienced work-related accident abroad. The participants suggested that the reasons behind this are not only health and safety at work but also poor communication, taking risks by workers themselves, and perceived work pressure. Some participants experienced serious incidents causing life-long disability, extreme and harrowing accounts of injury but received no support from their employer or host countries. Nepali migrant workers would appear to be at a high risk of workplace unintentional injuries owing to a number of interrelated factors poor health and safety at work, pressure of work, risk taking practices, language barriers, and their general work environment. Both the Government of Nepal and host countries need to be better policing existing policies, introduce better legislation where necessary, ensure universal health (insurance) coverage for labour migrants, and improve preventive measures to minimize the number and severity of accidents and injuries among migrant workers
String Nature of Confinement in (Non-)Abelian Gauge Theories
Recent progress achieved in the solution of the problem of confinement in
various (non-)Abelian gauge theories by virtue of a derivation of their string
representation is reviewed. The theories under study include QCD within the
so-called Method of Field Correlators, QCD-inspired Abelian-projected theories,
and compact QED in three and four space-time dimensions. Various
nonperturbative properties of the vacua of the above mentioned theories are
discussed. The relevance of the Method of Field Correlators to the study of
confinement in Abelian models, allowing for an analytical description of this
phenomenon, is illustrated by an evaluation of field correlators in these
models.Comment: 100 pages, LaTeX2e, no figures, 1 table, based on the Ph.D. thesises
at the Humboldt University of Berlin (1999) (available under
http://dochost.rz.hu-berlin.de) and the Institute of Theoretical and
Experimental Physics, Moscow (2000), new results are included, extended with
respect to the journal versio
A weak scientific basis for gaming disorder: let us err on the side of caution
We greatly appreciate the care and thought that is evident in the 10 commentaries that discuss our debate paper, the
majority of which argued in favor of a formalized ICD-11 gaming disorder. We agree that there are some people
whose play of video games is related to life problems. We believe that understanding this population and the nature
and severity of the problems they experience should be a focus area for future research. However, moving from
research construct to formal disorder requires a much stronger evidence base than we currently have. The burden of
evidence and the clinical utility should be extremely high, because there is a genuine risk of abuse of diagnoses. We
provide suggestions about the level of evidence that might be required: transparent and preregistered studies, a better
demarcation of the subject area that includes a rationale for focusing on gaming particularly versus a more general
behavioral addictions concept, the exploration of non-addiction approaches, and the unbiased exploration of clinical
approaches that treat potentially underlying issues, such as depressive mood or social anxiety first. We acknowledge
there could be benefits to formalizing gaming disorder, many of which were highlighted by colleagues in their
commentaries, but we think they do not yet outweigh the wider societal and public health risks involved. Given the
gravity of diagnostic classification and its wider societal impact, we urge our colleagues at the WHO to err on the side
of caution for now and postpone the formalization
Properties of Graphene: A Theoretical Perspective
In this review, we provide an in-depth description of the physics of
monolayer and bilayer graphene from a theorist's perspective. We discuss the
physical properties of graphene in an external magnetic field, reflecting the
chiral nature of the quasiparticles near the Dirac point with a Landau level at
zero energy. We address the unique integer quantum Hall effects, the role of
electron correlations, and the recent observation of the fractional quantum
Hall effect in the monolayer graphene. The quantum Hall effect in bilayer
graphene is fundamentally different from that of a monolayer, reflecting the
unique band structure of this system. The theory of transport in the absence of
an external magnetic field is discussed in detail, along with the role of
disorder studied in various theoretical models. We highlight the differences
and similarities between monolayer and bilayer graphene, and focus on
thermodynamic properties such as the compressibility, the plasmon spectra, the
weak localization correction, quantum Hall effect, and optical properties.
Confinement of electrons in graphene is nontrivial due to Klein tunneling. We
review various theoretical and experimental studies of quantum confined
structures made from graphene. The band structure of graphene nanoribbons and
the role of the sublattice symmetry, edge geometry and the size of the
nanoribbon on the electronic and magnetic properties are very active areas of
research, and a detailed review of these topics is presented. Also, the effects
of substrate interactions, adsorbed atoms, lattice defects and doping on the
band structure of finite-sized graphene systems are discussed. We also include
a brief description of graphane -- gapped material obtained from graphene by
attaching hydrogen atoms to each carbon atom in the lattice.Comment: 189 pages. submitted in Advances in Physic
Broadband semiconductor light sources operating at 1060 nm based on InAs:Sb/GaAs submonolayer quantum dots
In this paper, we investigate the potential of submonolayer-grown InAs:Sb/GaAs quantum dots as active medium for opto-electronic devices emitting in the 1060 nm spectral range. Grown as multiple sheets of InAs in a GaAs matrix, submonolayer quantum dots yield light-emitting devices with large material gain and fast recovery dynamics. Alloying these structures with antimony enhances the carrier localization and red shifts the emission, whereas dramatically broadening the optical bandwidth. In a combined experimental and numerical study, we trace this effect to an Sb-induced bimodal distribution of localized and delocalized exciton states. While the former do not participate in the lasing process, they give rise to a bandwidth broadening at superluminescence operation and optical amplification. Above threshold laser properties like gain and slope efficiency are mainly determined by the delocalized fraction of carriers
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