The late-time development of the Richtmyer–Meshkov instability

Measurements have been made of the growth by the Richtmyer–Meshkov instability of nominally single-scale perturbations on an air/sulfur hexafluoride (SF6) interface in a large shock tube. An approximately sinusoidal shape is given to the interface by a wire mesh which supports a polymeric membrane separating the air from the SF6. A single shock wave incident on the interface induces motion by the baroclinic mechanism of vorticity generation. The visual thickness delta of the interface is measured from schlieren photographs obtained singly in each run and in high-speed motion pictures. Data are presented for delta at times considerably larger than previously reported, and they are tested for self-similarity including independence of initial conditions. Four different initial amplitude/wavelength combinations at one incident shock strength are used to determine the scaling of the data. It is found that the growth rate decreases rapidly with time, ddelta/dt[proportional]t–p (i.e., delta[proportional]t1–p), where 0.67<~p<~0.74 and that a small dependence on the initial wavelength lambda0 persists to large time. The larger value of the power law exponent agrees with the result of the late-time-decay similarity law of Huang and Leonard [Phys. Fluids 6, 3765–3775 (1994)]. The influence of the wire mesh and membrane on the mixing process is assessed

A study of the vibrational spectra of some monosubstituted benezene derivatives of group VIA of the periodic table

The vibrational frequencies for (C6H5)2Se, (C6H5)2Te, (C6H5)2Se2, (C6H5)2Te2, (C6H5)2Hg, and (C6H5-Se)2Hg are completely assigned and are consistent with the vibrational assignments for (C6H5)2O, (C6H5)2S, and (C6H5)2S2 previously reported. Further, whereas (C6H5)2O and to a lesser extent (C6H5)2S show vibrational spectra consistent with non-equivalence of the two phenyl rings attached to the central atom, the spectra of the other molecules show little evidence for such non-equivalency of the two phenyl rings. The infrared spectra of (C6H5-X)2Hg, where X = S or Se, and the spectra of structurally related molecules indicate that the mercury atom has no significant effects on the vibrations of the phenyl ring other than slight displacements of some frequencies as a result of interactions of central skeletal vibrations with ring vibrations. The vibrational assignments for (C6H5)2Te confirms the linearity of the Gordy Rule plot of the t-vibration for Group VIA Elements

The Use of Social Networking Sites (SNSs) to Promote Personal Learning by Saudi Arabian University Students

In recent years, there have been increasing demands for the use of digital technology, especially social networking sites, in higher education around the world to enhance students’ learning at university. This study was carried out to explore the use of SNSs by female Hail University students in Saudi Arabia to promote personal learning. It investigated the factors that influence their use of these sites to promote their personal learning. Self-directed learning theory, affordance theory, identity and agency concepts were adopted to understand the issue under investigation. The study was conducted under the umbrella of the interpretive philosophical stance in order to investigate the issue in depth. Case study was adopted as the research methodology using the Self-Directed Learning (SDL) closed-ended questionnaire (522 participants), semi-structured interviews (27 participants) and text diaries (10 participants) to collect both quantitative and qualitative data. The sample of the three instruments consisted of students from both scientific and social sciences colleges. The study revealed several important findings related to the use of SNSs among Saudi university students for personal learning. Four significant outcomes were highlighted. The first was that the students’ sense of agency and what the students thought about their own, as against their lecturers', responsibilities in their learning played a major role in their personal learning and in their relationship with their lecturers in the learning context. Secondly, the students’ recognition of the technical and educational affordances of these social networks was another important element that formed their relationship with this technology and the way they used it for personal learning. Thirdly, the skills of using social networks and the strategy they followed in order to perform personal learning was an important element that influenced their use of these sites for personal learning. As this study focused on Saudi Arabian female students, who are part of a unique conservative community, the importance of cultural aspects in influencing the students' perceptions and performance of personal learning through social networks was the fourth significant outcome highlighted

An Alternative Proposal of Justice: Muslim Women Activists and Socio-Legal Realities in India

In India, with the change of political leadership at the center, the sanctity of religion- based Muslim family law has been contested. This has led to the development of a new socio-political discourse which is influenced and shaped by the basic feminist ideals of equal rights for women. In this discourse, Muslim women are portrayed as necessarily suffering from unjust family laws and needing immediate cover and protection from the secular state. In the light of the judicial reform which makes the practice of instant divorce through ‘triple talaq’ among Muslims a punishable offence, this article discusses that for Muslim women the domain of law is liminal and they choose between multiple legal forums to increase their access to justice. It explores how Muslim women approach different alternative forums, and in what ways Muslim women activists are creating an opportunity for the distressed women to resolve their marital disputes more efficiently. Such an examination provides important insights into how Muslim women’s rights activists undertake their pursuit of justice within a complex, legally pluralistic landscape in the area of Muslim family law in India