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Abstract Quasiparticles emerging in crystalline materials can possess a binary flavor known as the valley quantum number which can be used as a basis to encode information in an emerging class of valleytronic devices. Here we show that two-dimensional semimetals with tilted Dirac cones in the electronic band structure exhibit spatial separation of carriers belonging to different valleys under illumination. In stark contrast to gapped Dirac materials this optovalleytronic phenomenon occurs in systems with intact inversion and time-reversal symmetry that host gapless Dirac cones in the band structure, thereby retaining the exceptional graphene-like transport properties. We thus demonstrate that optical valley separation is possible at arbitrarily low photon frequencies including the deep infrared and terahertz regimes with full gate tunability via Pauli blocking. As a specific example of our theory, we predict tunable valley separation in the proposed two-dimensional tilted Dirac cone semimetal 8-Pmmn borophene for incident infrared photons at room temperature. This work highlights the potential of two-dimensional tilted Dirac cone materials as a platform for tunable broadband optovalleytronic applications.

Abstract We show that if the solutions to the (2+1)-dimensional massless Dirac equation for a given one-dimensional (1D) potential are known, then they can be used to obtain the eigenvalues and eigenfunctions for the same potential, orientated at an arbitrary angle, in a 2D Dirac material possessing tilted, anisotropic Dirac cones. This simple set of transformations enables all the exact and quasi-exact solutions associated with 1D quantum wells in graphene to be applied to the confinement problem in tilted Dirac materials such as 8-Pmmn borophene. We also show that smooth electron waveguides in tilted Dirac materials can be used to manipulate the degree of valley polarization of quasiparticles travelling along a particular direction of the channel. We examine the particular case of the hyperbolic secant potential to model realistic top-gated structures for valleytronic applications.

Abstract Color vision tests use estimative of threshold color discrimination or number of correct responses to evaluate performance in chromatic discrimination tasks. Both approaches have advantages and disadvantages. In the present investigation, we compared the number of errors during color discrimination task in normal trichromats and participants with color vision deficiency (CVD) using pseudoisochromatic stimuli at fixed saturation levels. We recruited 28 normal trichromats and eight participants with CVD. Cambridge Color Test was used to categorize their color vision phenotype, and those with a phenotype suggestive of color vision deficiency had their L- and M-opsin genes genotyped. Pseudoisochromatic stimuli were shown with target chromaticity in 20 vectors radiating from the background chromaticity and saturation of 0.06, 0.04, 0.03, 0.02, 0.01, and 0.005 u’v' units. Each stimulus condition appeared in four trials. The number of errors for each stimulus condition was considered an indicator of the participant's performance. At high chromatic saturation, there were fewer errors from both phenotypes. The errors of the normal trichromats had no systematic variation for high saturated stimuli, but below 0.02 u’v' units, there was a discrete prevalence of tritan errors. For participants with CVD, the errors happened mainly in red-green chromatic vectors. A three-way ANOVA showed that all factors (color vision phenotype, stimulus saturation, and chromatic vector) had statistically significant effects on the number of errors and that stimulus saturation was the most important main effect. ROC analysis indicated that the performance of the fixed saturation levels to identify CVD was better between 0.02 and 0.06 u’v’ units reaching 100%, while saturation of 0.01 and 0.005 u’v’ units decreased the accuracy of the screening of the test. We concluded that the color discrimination task using high saturated stimuli separated normal trichromats and participants with red-green color vision deficiencies with high performance, which can be considered a promising method for new color vision tests based in frequency of errors.

Breast cancer (BC) is a malignant tumor originating from the epithelium of the breast tissue. There is no single etiological factor in the development of breast cancer. In 310% of patients with breast cancer, the development of the disease is associated with the presence of mutations in the breast cancer gene (BRCA) 1, BRCA2, CHEK, NBS1, TP53. In other patients, breast cancer is sporadic.

Drawing upon standpoint theory and phenomenology, this study chronicles the lived experiences of 16 successful female first-generation students of color as they pursued K-12 schooling and accessed higher education. Findings indicate that a complex set of school, family, peer, and personal factors affected students' lived experiences in their urban environments; three holistic student profiles illustrate the interconnectedness of these factors. Stories of successful female first-generation students of color demonstrate how they, despite facing numerous challenges, used resistance and resilience during their K-12 urban schooling and when accessing higher education.

Optics: Optimising Luminescent Solar Concentrators for applications in optical systems Modelling the bandwidth limits of Luminescent Solar Concentrators (LSCs) offers vital insights into their behaviour and provides a technique for evaluating their use in various applications. Although LSCs have emerged as a promising receiver technology in free-space optical communications due to their ability to collect light from a wide field-of-view and concentrate it into small areas, the comparably slow timescale of their fluorescence events may pose a bottleneck on the bandwidth of high-speed communication systems. A team of researchers led by Ioannis Papakonstantinou from University College London has developed a technique that delineates the fundamental limits of LSCs as optical detectors and demonstrated time-domain Monte-Carlo simulation for optimising LSC based receiver systems. The work opens the door for the use of LSCs in applications in visible light communications, high-speed video recording, and real-time biological imaging.

Background: Folliculo-stellate cells were first identified with electron microscopy as a non-hormone secreting accessory cells, star-shaped and follicleforming cells. They represent about 4-20% of pituitary cells from the anterior pituitary lobe. The folliculo-stellate cells control several anterior pituitary activities. However, they do not produce hormones, but they produce growth factors, cytokines, vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), leukemia inhibitory factor (LIF), IL-6, and macrophage migration inhibitory factor (MIF), IL-1β and TNF-α. Regardless of a long period of pituitary research and many morphological, cytophysiological studies, it has been reported that a precise understanding of the major functions of folliculo-stellate in the pituitary gland remains unknown. Consequently, there are still many unsolved issues. Conclusions: This article intends to review the characteristics of folliculo-stellate cells and their uncertain functions in the adenohypophysis, such as their importance as stem cells, in the process of maturation and aging. New researches about the origin and differentiation of folliculo-stellate cells may provide many relevant answers about physiopathology of the pituitary gland and the pathogenesis of pituitary tumors, as well as their influence on the quality of life. Immunohistochemical profile studies of folliculo-stellate cells in pituitary gland, can be useful in elucidation of morphological features and may have a predictive role for the early identification of pituitary microadenomas, prognosis of pituitary tumors and treatment.

Abstract We theoretically investigate the problem of an electron confined to a nanohelix between two parallel gates modelled as charged wires. The double-gated nanohelix system is a binary superlattice with properties highly sensitive to the gate voltages. In particular, the band structure exhibits energy band crossings for certain combinations of gate voltages, which could lead to quasi-relativistic Dirac-like phenomena. Our analysis for optical transitions induced by linearly and circularly polarized light suggests that a double-gated nanohelix can be used for versatile optoelectronic applications.

The efficiency of deep cooling air at the inlet of gas turbine unite to the temperature of 10 °С by waste heat recovery combined absorption-ejector chiller was analyzed in climatic conditions at Kharkov site, Ukraine, and Beijing site, China, and compared with the moderate cooling to the temperature of 15°C in traditional absorption lithium-bromide chiller. The refrigerant ejector chiller is chosen as the most simple and reliable in operation chiller. It was used as the low-temperature stage for subcooling the air precooled in absorption lithium-bromide chiller to the temperature about 15 °C. Both waste heat recovery absorption lithium-bromide chiller and ejector chiller use the heat of gas turbine unite exhaust gas to produce a cooling capacity. Air cooling at the inlet of gas turbine unite was investigated for varying climatic conditions during the year. The current values of temperature depression with cooling ambient air to different temperatures of 10 °C and 15 °C and corresponding cooling capacities required were calculated. The comparison of the effect due to gas turbine unite inlet air cooling was performed by annual fuel saving and power production growth. With this the current values of turbine power output increase and specific fuel consumption decrease due to cooling inlet air from current varying ambient temperatures to the temperatures of 10 °C and 15 °C were calculated. It was shown that annual fuel saving and power production growth have increased by 1,8 times for Kharkov (Ukraine) site climatic conditions and by 1,6 times for Beijing (China) site due to deep cooling air to the temperature of 10 °C by absorption-ejector chiller as compared with cooling inlet air to the temperature of 15 °C by absorption lithium-bromide chiller.

In this paper we study the effect of absorption peak correlation in finite length carbon nanotubes and graphene nanoribbons. It is shown, in the orthogonal π-orbital tight-binding model with the nearest neighbor approximation, that if the ribbon width is a half of the tube circumference the effect takes place for all achiral ribbons (zigzag, armchair and bearded), and corresponding tubes, starting from lengths of about 30 nm. This correlation should be useful in designing nanoribbon-based optoelectronics devices fully integrated into a single layer of graphene. Keywords: Advanced materials, Graphene, Quasi-one-dimensional structures, Finite length, Tight-binding model, Cluster approximation, Optical absorption, Selection rules

We predict an optical effect associated with systems, which exhibit topologically protected states separated by a finite distance. We develop a tight-binding model to calculate the optical selection rules in linear chains of atoms of different lengths, and show the crucial importance of edge states. For long enough molecules the interband transitions involving these edge states are in the highly sought-after THz frequency range. Although we have specifically considered finite carbon chains terminated by gold nanoparticles, the main results of our paper can be generalized to various systems, which exhibit topologically protected states separated by a finite distance.

Two-dimensional Dirac semimetals are known to host fermionic excitations which can mimic physics usually found in ultrarelativistic quantum mechanics. Here, the authors unveil the existence of another type of quasiparticle, bielectron vortices, which are bosonic and may give rise to new types of condensates.

Color vision assessment can be done using pseudoisochromatic stimuli, which has a luminance noise to eliminate brightness differences between the target and background of the stimulus. It is not clear the influence of the luminance noise on color discrimination. We investigated the effect of change in the luminance noise limits on color discrimination. Eighteen trichromats and ten congenital dichromats (eight protans, two deutans) had their color vision evaluated by the Cambridge Colour Test, and were genetically tested for diagnostic confirmation. The stimuli were composed of a mosaic of circles in a 5° circular field. A subset of the circles differed in chromaticity from the remaining field, forming a letter C. Color discrimination was estimated in stimulus conditions differing in luminance noise range: (i) 6–20 cd/m2; (ii) 8–18 cd/m2; (iii) 10–16 cd/m2; and (iv) 12–14 cd/m2. Six equidistant luminance values were used within the luminance noise limits with the mean stimulus luminance maintained constant under all conditions. A four-alternative, forced-choice method was applied to feed a staircase procedure to estimate color discrimination thresholds along eight chromatic axes. An ellipse model was adjusted to the eight color discrimination thresholds. The parameters of performance were threshold vector lengths and the ellipse area. Results were compared using the Kruskal-Wallis test with a significance level of 5%. The linear function model was applied to analyze the dependence of the discrimination parameters on the noise luminance limits. The first derivative of linear function was used as an indicator of the rate of change in color discrimination as a function of luminance noise changes. The rate of change of the ellipse area as a function of the luminance range in dichromats was higher than in trichromats (p < 0.05). Significant difference was also found for individual thresholds in half of the axes we tested. Luminance noise had a greater effect on color discrimination ability of dichromats than the trichromats, especially when the chromaticities were close to their protan and deutan color confusion lines.

Doctoral student socialization is the process through which emerging scholars are inducted into their academic disciplines and the academic profession. Recent doctoral student socialization literature has expanded upon traditional notions of the process to re-conceptualize it as multidirectional and complex. This study contributes to further enriching the doctoral student socialization framework by positing doctoral student agency as central to this process. Utilizing doctoral student voices, the study documents how doctoral students exercise agency through engaging dissertation advisors and other faculty, enlisting peers, and owning their status as scholars. Given continued calls to improve doctoral education, understanding the role doctoral students play in their own socialization is critical--both for doctoral students and for the faculty who participate in educating them.

South African higher education has been experiencing profound and vigorous transformations in the post-apartheid era. At the same time, global trends toward competition and employment equity contribute to the complexities of the country's higher education environment. These global and local developments combine to impact the working environment of South African academics. This qualitative study employed a phenomenological approach to explore the "lived" experiences of 20 South African academics operating within this changing academic workplace at a case study institution. Although the findings pointed to several "pull" factors representing positive aspects of the university's working environment, six "push" factors emerged as the study's most salient and robust research findings: (1) lack of induction/training, (2) working with underprepared students, (3) unmanageable workloads, (4) issues of race and power, (5) challenges for female academics, and (6) frustrations regarding slow institutional change. An additional key theme centered on findings related to potential decisions to depart from the institution or academia. When combined with prior research, the findings suggest an imperative for South African higher education institutions to focus on improving the environment in which academic staff conduct their work, particularly given the post-apartheid impetus to transform institutions for both equity and global competition purposes.

In this final chapter of the volume, the editors synthesize key themes that emerge from the preceding chapters. They also highlight the contributions the authors make through emphasizing critical perspectives and the tension between global and local forces.

In this chapter, the issue editors set the stage for the chapters that follow by delineating recent developments in higher education and common strategies for creating globally competitive higher education institutions. The editors consider social justice concerns that arise with global competition and contend that contextualized priorities can and should mediate global trends.

Scholars often view pursuing the doctoral degree as the process of socialization into the academic profession. Yet, doctoral students have several career pathways from which to choose. With this study, we build upon existing literature to develop a more comprehensive understanding of current doctoral students' preparation for academia and other career pathways, how they are socialized into the academic profession, and the complex and interconnected factors they perceive as affecting their career decision-making processes. The majority of the participants planned to continue in academia. Among the factors survey participants reported as most salient when choosing a career were enjoyment of the job, the ability to conduct original research, and the ability to raise a family.