Catching VY Sculptoris in a low state

Context. In the context of a large campaign to determine the system parameters of high mass transfer cataclysmic variables, we found VY Scl in a low state in 2008. Aims. Making use of this low state, we study the stellar components of the binary with little influence of the normally dominating accretion disc. Methods. Time-resolved spectroscopy and photometry of VY Scl taken during the low state are presented. We analysed the light-curve and radial velocity curve and use time-resolved spectroscopy to calculate Doppler maps of the dominant emission lines. Results. The spectra show narrow emission lines of Halpha, Hbeta, HeI, NaID, and FeII, as well as faint TiO absorption bands that trace the motion of the irradiated secondary star, and Halpha and HeI emission line wings that trace the motion of the white dwarf. From these radial velocities, we find an orbital period of 3.84 h, and put constraints on binary parameters such as the mass ratio M2/M1 of 0.43 and the inclination of 15 deg. With a secondary's mass between 0.3 and 0.35 Msol, we derive the mass for the white dwarf as M1 = 0.6-0.1 Msol.Comment: 8 pages, 9 figures, accepted for publication in A&

Statistical model of dephasing in mesoscopic devices introduced in the scattering matrix formalism

We propose a phenomenological model of dephasing in mesoscopic transport, based on the introduction of random phase fluctuations in the computation of the scattering matrix of the system. A Monte Carlo averaging procedure allows us to extract electrical and microscopic device properties. We show that, in this picture, scattering matrix properties enforced by current conservation and time reversal invariance still hold. In order to assess the validity of the proposed approach, we present simulations of conductance and magnetoconductance of Aharonov-Bohm rings that reproduce the behavior observed in experiments, in particular as far as aspects related to decoherence are concerned.Comment: 6 pages, 6 figure

The women's group programme in the S.R.D.P.

This paper is based primarily on research carried out as part of the Second Overall Evaluation of the Special Rural Development Programme conducted by the Institute for Development Studies in 1975. The paper begins with a general description and evaluation of the Women's Group Programme and then presents case studies of the six S.R.D.P. areas: Kapenguria, Kwale, Mbere, Migori/Kuria, Tetu and Vihiga/Hamisi. Eor each area, a brief description is given of the women who attended the leaders training courses offered as part of the Programme. The courses themselves are also described. Membership figures are given for the women's groups in the six areas, as well as brief accounts of group activities and plans. Finally, the role of local government officers is described - the frequency of contacts, the specific offices and ministries involved, and the nature of the assistance given. In general, the Women's Group Programme i s found to be a successful effort in the field of rural development which should be continued and expanded. A number of recommendations are made for improvement, both of the Programme in general and in specific S.R.D.P. areas. The broad participation and increased cooperation of a number of ministries and other agencies is recommended, both at the national level and in the field. It is also suggested that the objectives and curricula of the courses for women's leaders be brought more sharply into focus. Emphasis should also be placed on new approaches to income generation for women's groups, in addition to the traditional focus on family welfare and handicrafts. (I The general section of this paper appeared as Chapter Fifteen of I.D.S. Occasional Paper No. 12, and the case studies first appeared as I.D.S. Working Papers Nos. 231 - 236

Effects of nicotine administration in rats on MMP2 and VEGF levels in periodontal membrane

Background: Nicotine is associated with increased incidence of periodontal disease and poor response to therapy. This article aimed at identifying the expression of matrix metalloproteinases 2 (MMPs2) and vascular endothelial growth factor (VEGF) proteins on extracellular matrix, fibrous distribution and angiogenetic development in periodontitis caused by nicotine effects on periodontal membrane.Materials and methods: In this experimental study, rats were divided into nicotine and control groups. While the rats in the nicotine group (n = 6) were administered 2 mg/kg nicotine sulphate for 28 days, the animals in the control group (n = 6) were only administered 1.5 mL physiologic saline solution subcutaneously for 28 days.Results: Histological sections were prepared and immunohistochemically stained for MMP2 and VEGF. The sections stained with Trichrome-Masson were observed under light microscope. VEGF and MMP2 immunoreactivity of periodontal gingiva and dentin was assessed by immunohistochemical staining.Conclusions: Nicotine reduces MMP production, disrupts collagen synthesis and causes periodontitis. We observed that nicotine increases periodontitis by disrupting periodontal membrane and prevents tooth to anchor in dental alveoli by disrupting epithelial structure

Masking capacity of minimally invasive lithium disilicate restorations on discolored teeth-The impact of ceramic thickness, the material's translucency, and the cement color.

OBJECTIVES To evaluate minimally invasive restorations' capacity to mask discolored teeth and explore the impact of ceramic thickness, translucency, and cement color. MATERIALS AND METHODS Twenty-four assessment pairs of naturally colored and discolored bovine dentin samples were formed, using lithium disilicate specimens in six different thicknesses (0.3-0.8 mm), two different translucencies (high, low), and two cements (transparent, tooth-colored). Evaluators assessed the color differences in each assessment pair, and the threshold for detecting a color difference was determined using sequential testing and the Bonferroni-Holm method. RESULTS A thickness of 0.6 mm effectively masked color differences using high translucent ceramic with transparent cement, detectable differences were still observed at 0.7/0.8 mm. A threshold thickness of 0.4 mm was seen using high translucent ceramic and tooth-colored cement, with color differences still discernible at 0.5 and 0.8 mm. A threshold thickness of 0.4 mm was detected using low translucent ceramic and transparent cement, while detectable differences persisted at 0.5, 0.7, and 0.8 mm. A 0.5 mm threshold thickness was observed when using low translucent ceramic and tooth-colored cement, and no detectable color differences were detected beyond this thickness. CONCLUSIONS Masking can be achieved with a thickness of 0.4-0.5 mm using a low translucent material and tooth-colored cement. CLINICAL SIGNIFICANCE Understanding the impact of ceramic thickness, translucency, and cement color can aid clinicians in making informed decisions for achieving the best esthetic outcomes while preserving tooth structure. Effective masking can be accomplished with ceramic thicknesses starting at 0.4 mm, especially when employing a low translucent material and tooth-colored cement. However, clinicians should be aware that discolorations may still be detectable in certain scenarios when using minimally invasive lithium disilicate restorations

Towards a volumetric census of close white dwarf binaries I.Reference samples

Close white dwarf binaries play an important role across a range of astrophysics, including thermonuclear supernovae, the Galactic low-frequency gravitational wave signal, and the chemical evolution of the Galaxy. Progress in developing a detailed understanding of the complex, multi-threaded evolutionary pathways of these systems is limited by the lack of statistically sound observational constraints on the relative fractions of various sub-populations, and their physical properties. The available samples are small, heterogeneous, and subject to a multitude of observational biases. Our overarching goal is to establish a volume-limited sample of all types of white dwarf binaries that is representative of the underlying population as well as sufficiently large to serve as a benchmark for future binary population models. In this first paper, we provide an overview of the project, and assemble reference samples within a distance limit of 300\,pc of known white dwarf binaries spanning the most common sub-classes: post-common envelope binaries containing a white dwarf plus a main sequence star, cataclysmic variables and double-degenerate binaries. We carefully vet the members of these "Gold" Samples, which span most of the evolutionary parameter space of close white dwarf binary evolution. We also explore the differences between magnitude and volume limited close white dwarf binary samples, and discuss how these systems evolve in their observational properties across the Gaia Hertzsprung-Russell diagram.Comment: Accepted for publication in MNRAS on 11/3/2021 following peer revie

The Role of Legumes in Sustainable Cereal Production in Rainfed Areas

Cool season food legumes (CSFL) are minor crops compared to cereals, but they are important in farming systems, in human and animal nutrition and as a source of biological N. They protect the soil from erosion, add organic matter, fix nitrogen and spare soil mineral N as well as helping control cereal diseases. They provide more flexible weed control options. Two major factors may lead to the increased use of cool season food legumes in cereal based cropping systems. The first is the demand for grain with a high protein content and other nutritional factors, for human and animal consumption. The second is the realisation of their importance as a “break” crop in continuous non-legume cropping systems. The contribution of pulses to increased cereal production will come from a better understanding of rotations and production packages, better information on the residual effects of legumes, development of simulation models to predict these effects and the enhancement of biological N2 fixation. The pulses themselves require continued support to develop better disease resistance, higher yields, better fashioned cultivars for specific cropping environments, technological packages and extension support and, more sophisticated local and international marketing strategies. Cereal-legume rotations enable the use of different herbicides in the respective crops and reduce the risk of herbicide resistance in weeds

Rashba spin precession in quantum Hall edge channels

Quasi--one dimensional edge channels are formed at the boundary of a two-dimensional electron system subject to a strong perpendicular magnetic field. We consider the effect of Rashba spin--orbit coupling, induced by structural inversion asymmetry, on their electronic and transport properties. Both our analytical and numerical results show that spin--split quantum--Hall edge channels exhibit properties analogous to that of Rashba--split quantum wires. Suppressed backscattering and a long spin life time render these edge channels an ideal system for observing voltage--controlled spin precession. Based on the latter, we propose a magnet--less spin--dependent electron interferometer.Comment: 7 pages, 6 figure