Identifying industry defined best practices within educational YouTube content, an exploratory study

Master's Project (M.A.) University of Alaska Fairbanks, 201

A Theoretical Assessment of the Influence of Myosin Filament Dispersion on Smooth Muscle Contraction

ABSTRACT A new constitutive model for the biomechanical behavior of smooth muscle tissue is employed to investigate the influence of statistical dispersion in the orientation of myosin filaments. The number of activated cross-bridges between the actin and myosin filaments governs the contractile force generated by the muscle and also the contraction speed. A strain-energy function is used to describe the mechanical behavior of the smooth muscle tissue. The predictions from the constitutive model are compared to histological and isometric tensile test results for smooth muscle tissue from swine carotid artery. In order to be able to predict the active stress at different muscle lengths, a filament dispersion significantly larger than the one observed experimentally was required. Furthermore, a comparison of the predicted active stress for a case of uniaxially oriented myosin filaments and a case of filaments with a dispersion based on the experimental histological data shows that the difference in generated stress is noticeable but limited. Thus, the results suggest that myosin filament dispersion alone cannot explain the increase in active muscle stress with increasing muscle stretch

Accurate intensity integration in the twinned γ-form of o-nitro­aniline

o-Nitro­aniline, C6H6N2O3, is known to be polymorphic. The α-form is probably amorphous, while the β- and γ-forms are crystalline. Difficulties with the unit-cell determination of the γ-form were reported as a consequence of twinning. In this paper, newly recorded diffraction data of the γ-form of o-nitro­aniline are described that were processed taking into account the two twin lattices. Data were partly deconvoluted and much better agreement was obtained in terms of R1 values and C—C bond precision. The availability of raw data and proper reprocessing using twin lattices is by far superior to efforts to de-twin processed structure factors

A railway timetable rescheduling approach for handling large scale disruptions

On a daily basis, relatively large disruptions require infrastructure managers and railway operators to reschedule their railway timetables together with their rolling stock and crew schedules. This research focuses on timetable rescheduling for passenger trains at a macroscopic level in a railway network. An integer programming model is formulated for solving the timetable rescheduling problem, which minimizes the number of cancelled and delayed trains while adhering to infrastructure and rolling stock capacity constraints. The possibility of rerouting trains in order to reduce the number of cancelled and delayed trains is also considered. In addition, all stages of the disruption management process (from the start of the disruption to the time the normal situation is restored) are taken into account. Computational tests of the described model on a heavily used part of the Dutch railway network show that we are able to find optimal solutions in short computation times. This makes the approach applicable for use in practice

Use of skin substitute dressings in the treatment of staphylococcal scalded skin syndrome in neonates and young infants

Background: Staphylococcal scalded skin syndrome (SSSS) is a rare toxin-mediated skin disease caused by Staphylococcus aureus and seen in infants and children younger than 5 years. Objectives: The supportive role of skin substitutes in SSSS is stressed as a new and relatively unknown method. Methods: Retrospective observational case-series study, in neonates and young infants diagnosed with SSSS. Results: Seven infants with SSSS, treatment with antibiotics, skin substitutes, strict pain relief strategy and prognosis were described. One of them was severely affected and deceased. Conclusion: This study describes 7 infants with SSSS and stresses the important role of skin substitutes as Omiderm® and Suprathel® as valuable adjuvant treatment modality. Copyrigh

NETWORKED2‐Subfamily Proteins Regulate the Cortical Actin Cytoskeleton of Growing Pollen Tubes and Polarised Pollen Tube Growth

We have recently characterised NET2A as a pollen‐specific actin‐binding protein which binds F‐actin at the plasma membrane of growing pollen tubes. However, the role of NET2 proteins in pollen development and fertilisation have yet to be elucidated. To further characterise the role of Arabidopsis NET2 proteins in pollen development and fertilisation, we analysed the subcellular localisation of NET2A over the course of pollen grain development, and investigated the role of the NET2 family using net2 loss‐of‐function mutants. We observed NET2A to localise to the F‐actin cytoskeleton in developing pollen grains as it underwent striking structural reorganisations at specific stages of development and during germination, and pollen tube growth. Furthermore, net2 loss‐of‐function mutants exhibited striking morphological defects in the early stages of pollen tube growth, arising from frequent alterations to pollen tube growth trajectory. We observed defects in the cortical actin cytoskeleton and actin‐driven subcellular processes in net2 mutant pollen tubes. We demonstrate that NET2 proteins are essential for normal actin‐driven pollen development highlighting an important role for the NET2 family members in regulating pollen tube growth during fertilisation

Crystal structure of the second extracellular domain of human tetraspanin CD9: twinning and diffuse scattering

Remarkable features are reported in the diffraction pattern produced by a crystal of the second extracellular domain of tetraspanin CD9 (deemed CD9EC2), the structure of which has been described previously [Oosterheert et al. (2020[Oosterheert, W., Xenaki, K. T., Neviani, V., Pos, W., Doulkeridou, S., Manshande, J., Pearce, N. M., Kroon-Batenburg, L. M. J., Lutz, M., van Bergen en Henegouwen, P. M. P. & Gros, P. (2020). Life Sci. Alliance, 3, e202000883.]), Life Sci. Alliance, 3, e202000883]. CD9EC2 crystallized in space group P1 and was twinned. Two types of diffuse streaks are observed. The stronger diffuse streaks are related to the twinning and occur in the direction perpendicular to the twinning interface. It is concluded that the twin domains scatter coherently as both Bragg reflections and diffuse streaks are seen. The weaker streaks along c* are unrelated to the twinning but are caused by intermittent layers of non-crystallographic symmetry related molecules. It is envisaged that the raw diffraction images could be very useful for methods developers trying to remove the diffuse scattering to extract accurate Bragg intensities or using it to model the effect of packing disorder on the molecular structure

A high-resolution stable isotope record from a Peruvian stalagmite

Speleothems are known as carbonate formations in caves. The last few years there is a growing scientific interest in speleothems for climate reconstruction (McDermott, in press; Sancho et al., in press; Jirnénez de Cisneros et al., 2003; Genty et al., 2003; Baker et al., 2002; Proctor et al., 2002; Linge et al., 2001; Wang et al., 2001). Speleothems have proven their potential to create a terrestrial high-resolution paleo-temperature record (Schwarcz, 1986). The advantage of caves for paleoclimatic studies is the yearly stability of climatic conditions in the cave (Jirnénez de Cisneros et al., 2003). Observations have shown that the temperature in any deep cave is clase to the mean annual temperature of the surrounding (Schwarcz et al., 1976; Yonge et al., 1985). This makes speleothems a successful too! paleo-temperature reconstruction (Hendy and Wilson, 1968). The carbonate, ofwhich the speleothem is build, can be used for stable isotope measurements (o13C and o180). Oxygen isotopes are world-wide used to reconstruct paleo-temperatures, especially for biogenic carbonate in marine cores. Precise age-dating on speleothems can be done by U-Th measurements on TIMS, which makes it possible to calculate absolute ages for the isotope record