Nonequilibrium pattern formation in chiral Langmuir monolayers with transmembrane flows

Nonequilibrium Langmuir monolayers including a fraction of chiral molecules and subject to transmembrane flow are considered. The flow induces coherent collective precession of chiral molecules. Our theoretical study shows that splay interactions in this system lead to spatial redistribution of chiral molecules and formation of spiral waves and target patterns observed in experiments

Understanding preservice teachers’ perspectives on challenges experienced during work integrated learning

The demands on educational institutions in the 21st century are constantly changing, necessitating adapted teaching, and learning techniques both within and outside of the classroom. Central to these evolutionary changes is the teacher who is expected to initiate innovative teaching strategies that often come with a variety of challenges. This requires preservice teachers to consequently complete extensive work-integrated learning (WIL) for a defined period as part of their initial teacher training. The article sought to ascertain the challenges, faced by preservice teachers during WIL using the situated learning theory, which emphasises the relevance of the integration of new ideas and human actions in dealing with ongoing environmental challenges. The methodology of the study is built on an interpretive paradigm, employing a qualitative case study design. Data was collected through interviews from Fourteen B.Ed. Honours preservice teachers were selected through a non-probability sampling method, known as purposive sampling. Data analysis was done thematically and with the use of Atlas ti 9. The study found some degree of complexities and inter-relationship between the preservice teachers challenges and their inability to deliver content. Exceptionally, however, some challenges like the delegation of responsibilities, pedagogy and especially transportation issues show high-level association with an implication to WIL for preservice teachers. The study however makes some crucial recommendations to policy and practice, which include an expansion and emergency modification in teaching pedagogy to incorporate technology, mandatory professional training and induction programmes for mentors and the need to enhance the environmental approach to teachin

Neural network design and feature selection using principal component analysis and Taguchi method for identifying wood veneer defects

Nowadays, ensuring high quality can be considered the main strength for a company’s success. Especially, in a period of economic recession, quality control is crucial from the operational and strategic point of view. There are different quality control methods and it has been proven that on the whole companies using a continuous improvement approach, eliminating waste and maximizing productive flow, are more efficient and produce more with lower costs. This paper presents a method to optimize the quality control stage for a wood manufacturing firm. The method is based on the employment of the principal component analysis in order to reduce the number of critical variables to be given as input for an artificial neural network (ANN) to identify wood veneer defects. The proposed method allows the ANN classifier to identify defects in real time and increase the response speed during the quality control stage so that veneers with defects do not pass through the whole production cycle but are rejected at the beginning

Moult of overwintering Wood Warblers <i>Phylloscopus sibilatrix</i> in an annual-cycle perspective

Wood Warblers, an Afro-Palearctic migrant species, are declining steadily in Europe likely due to mortality outside their breeding grounds. However, little is known about their overwintering, and records about the sensitive life-cycle stage of moult in Africa are practically absent. To fill this gap, we report on moult of Wood Warblers captured over two winters (January–February) in 2019–2020 in Cameroon. We caught 14 individuals, of which 12 were monitored for flight feather moult. All inspected individuals showed advanced stages of flight feather renewal. Despite low sample sizes, Underhill-Zucchini moult models aptly explained variation in primary and secondary moult (R2 = 0.61). Estimated moult onset date was 26 December, completion date was 25 February, and moult duration was 61 days. These findings fit well with experimental data on the annual cycle and the timing of recently published migration tracks of Wood Warblers. Jointly, the data suggest that moult timing is set by an internal programme, which enables Wood Warblers to organise their multi-stage migration such that they reach suitable moulting habitat in time, and can depart in time with a fresh plumage for the breeding grounds. In our study, moult occurred during the peak of the dry season, which in Cameroon nonetheless shows high relative humidity. During our mist-netting on 28 cocoa plantations of varying shade cover, Wood Warblers were caught on 6 farms whose canopies were comparatively open. These data suggest that the birds encounter in Cameroon relatively stable climatic conditions for moult, and do not measurably prefer closed-canopy forests. Our findings are important, because successful moult increases survival prospects and because moult needs to be safely embedded in a migratory life cycle. Hence, information on moult timing and location is essential for identifying year-round vulnerabilities of Wood Warblers.<br/

Observation of Photovoltaic Effect and Single-photon Detection in Nanowire Silicon Pn-junction

We&nbsp; study&nbsp; nanowire&nbsp; silicon&nbsp; pin&nbsp; and&nbsp; pn-junctions&nbsp; at&nbsp; room&nbsp; and&nbsp; low&nbsp; temperature.&nbsp; Photovoltaic&nbsp; effects&nbsp; are&nbsp; observed&nbsp; for both devices at room temperature. At low temperature, nanowire pn-junction devices show their ability to detect single photon. This ability was not been observed for pin devices. Phosphorus-boron dopant cluster in the depletion region is considered&nbsp; to&nbsp; have&nbsp; the&nbsp; main&nbsp; role&nbsp; for&nbsp; single-photon&nbsp; detection&nbsp; capability.&nbsp; Fundamental&nbsp; mechanism&nbsp; of&nbsp; dopant-based single-photon detection in nanowire pn-junction is described in details

Laser information encoded in atomic asymmetrical ionization in few-cycle laser fields

The pulse duration and carry-envelope phase (CEP) are two important parameters to characterize a few-cycle intense laser. We systematically study asymmetrical ionization of Ar in few-cycle laser fields with different pulse durations (3–7 fs) and laser intensities (1013–1014 W/cm2) by solving the time-dependent Schrödinger equation. Analyzing the CEP-dependent asymmetry of above-threshold ionization as a function of the photoelectron energy, we find that the qualitative global features of CEP-dependent asymmetry are insensitive to the pulse duration. But the fine structures of the asymmetry are sensitive to the laser pulse duration. Changing Ar to H atoms, we find that the information encoded in asymmetry is insensitive to target atoms at a moderate laser intensity

Theory of monolayers with boundaries: Exact results and Perturbative analysis

Domains and bubbles in tilted phases of Langmuir monolayers contain a class of textures knows as boojums. The boundaries of such domains and bubbles may display either cusp-like features or indentations. We derive analytic expressions for the textures within domains and surrounding bubbles, and for the shapes of the boundaries of these regions. The derivation is perturbative in the deviation of the bounding curve from a circle. This method is not expected to be accurate when the boundary suffers large distortions, but it does provide important clues with regard to the influence of various energetic terms on the order-parameter texture and the shape of the domain or bubble bounding curve. We also look into the effects of thermal fluctuations, which include a sample-size-dependent effective line tension.Comment: replaced with published version, 21 pages, 16 figures include

Polar Smectic Films

We report on a new experimental procedure for forming and studying polar smectic liquid crystal films. A free standing smectic film is put in contact with a liquid drop, so that the film has one liquid crystal/liquid interface and one liquid crystal/air interface. This polar environment results in changes in the textures observed in the film, including a boojum texture and a previously unobserved spiral texture in which the winding direction of the spiral reverses at a finite radius from its center. Some aspects of these textures are explained by the presence of a Ksb term in the bulk elastic free energy density that favors a combination of splay and bend deformations.Comment: 4 pages, REVTeX, 3 figures, submitted to PR

Molecular Characterization of a Novel Methionine-Rich δ-Kafirin Seed Storage Protein Gene in Sorghum (Sorghum bicolor L.)

We have isolated, cloned, and characterized a 660 bp full length cDNA encoding a putative seed storage protein gene, delta-kafirin (AY834250), from developing seeds of sorghum (Sorghum bicolor) inbred line SPV475. Translation of the DNA sequence predicts a 16-kDa polypeptide (precursor) of 147 amino acids, rich in methionine residues (17%). Reverse Transcriptase-PCR (RT-PCR) and Real Time-PCR revealed delta-kafirin is only expressed in developing seeds. delta-Kafirin exhibited 96% identity with another methionine-rich sorghum seed storage protein (AY043223). Interestingly, this 6-kafirin gene contained two insertions rich in ATG codons encoding five more methionine residues than AY043223. Comparison of the sorghum delta-kafirin proteins with other seed storage proteins from maize, rice, and Brazil nut revealed conserved domains, mainly at the N-terminus. This similarity, in particular to the zeins, suggests these proteins shared a common ancestor and that the variation observed occurred after the separation of the species