Glassy dynamics in granular compaction

Two models are presented to study the influence of slow dynamics on granular compaction. It is found in both cases that high values of packing fraction are achieved only by the slow relaxation of cooperative structures. Ongoing work to study the full implications of these results is discussed.Comment: 12 pages, 9 figures; accepted in J. Phys: Condensed Matter, proceedings of the Trieste workshop on 'Unifying concepts in glass physics

Yelling Fire and Hacking: Why the First Amendment Does Not Permit Distributing DVD Decryption Technology?

One of the consequences of the black-hole "no-hair" theorem in general relativity (GR) is that gravitational radiation (quasi-normal modes) from a perturbed Kerr black hole is uniquely determined by its mass and spin. Thus, the spectrum of quasi-normal mode frequencies have to be all consistent with the same value of the mass and spin. Similarly, the gravitational radiation from a coalescing binary black hole system is uniquely determined by a small number of parameters (masses and spins of the black holes and orbital parameters). Thus, consistency between different spherical harmonic modes of the radiation is a powerful test that the observed system is a binary black hole predicted by GR. We formulate such a test, develop a Bayesian implementation, demonstrate its performance on simulated data and investigate the possibility of performing such a test using previous and upcoming gravitational wave observations

A two-species continuum model for aeolian sand ripples

We formulate a continuum model for aeolian sand ripples consisting of two species of grains: a lower layer of relatively immobile clusters, with an upper layer of highly mobile grains moving on top. We predict analytically the ripple wavelength, initial ripple growth rate and threshold saltation flux for ripple formation. Numerical simulations show the evolution of realistic ripple profiles from initial surface roughness via ripple growth and merger.Comment: 9 pages, 3 figure

Modelling highway-traffic headway distributions using superstatistics

We study traffic clearance distributions (i.e., the instantaneous gap between successive vehicles) and time headway distributions by applying Beck and Cohen's superstatistics. We model the transition from free phase to congested phase with the increase of vehicle density as a transition from the Poisson statistics to that of the random matrix theory. We derive an analytic expression for the spacing distributions that interpolates from the Poisson distribution and Wigner's surmise and apply it to the distributions of the nett distance and time gaps among the succeeding cars at different densities of traffic flow. The obtained distribution fits the experimental results for single-vehicle data of the Dutch freeway A9 and the German freeway A5.Comment: 10 pages, 2 figure

A Novel Human Neuronal Cell Model to Study Iron Accumulation in Parkinson’s Disease

Objectives: With an estimated seven to ten million sufferers worldwide, Parkinson’s disease (PD) is the second most common age-related neurodegenerative disorder. Progress in elucidating its causes has been slow, partly due to the lack of human-relevant models. Similarly, while the contribution of iron is increasingly advocated, identifying its role in disease progression remains challenging mainly due to the lack of valid model. In this study, we created Parkinson-like conditions in a human neuron model and conducted preliminary studies on iron-related parameters to assess whether these cells replicated iron accumulation observed in Parkinsonism. Methods: ReNcell VM (human neural progenitor) were differentiated into dopaminergic neurons (dDCNs) and treated with neurotoxin 6-hydroxy dopamine (100 μM) to mimic Parkinsonism. Total intracellular, mitochondrial and cytoplasmic iron was measured by ferrozine assay. Expression of iron-related genes TFRC, SLC40A1, HAMP and SLC25A37 were assessed through real-time PCR. Results: Data showed that the treated dDCNs accumulated iron over time and exceeded levels measured in untreated dDCNs by 2.5-fold at 48 h (p<0.02). Following the treatment, the treated cells showed lower expression of TFRC (p<0.05), but substantially higher mRNA expressions of SLC40A1 (9-fold; p<0.02) and HAMP (5.7-fold; p<0.05), along with higher intracellular iron (p<0.05). Higher iron accumulation in the mitochondria than cytosol (p<0.05), was also observed with increased expression of the mitochondrial iron-importer SLC25A37 (p=0.08). Conclusion: Our Parkinsonian model demonstrates iron accumulation and elevated HAMP expression as previously described in PD phenotype. The observed mitochondrial iron shuttling, which is proposed to be one of the primary contributors of oxidative stress in PD, calls for further investigation. The differences observed in distribution of iron in our human model and with the expression of major iron-related proteins, indicate that our model reproduces the disease state successfully, and suggests that further study could help in advancing our understanding of PD

Menstrual health management: Knowledge and practices among adolescent girls

Objectives: To assess the knowledge and attitude of adolescent girls regarding menstruation and menstrual hygiene.Material and Methods: After approval by the ethical committee , the study was conducted on 340 adolescent girls aged 12-19 years, belonging to an urban slum area of Delhi. This was a questionnaire based cross-sectional study conducted over a period of 9 months in a tertiary hospital. Confidentiality of the subjects was ensured.Results: Out of 340 girls 69 % were between 16-19 years. Source of information about menstruation in majority of the cases was mother (60%). Only 48% girls knew menstruation before menarche and 24% girls knew uterus as the organ for menstruation. 71 % girls used sterile sanitary napkins as absorbent. Satisfactory changing of pads (&gt;2pads/day) was done by 68 % and 77% girls cleaned the genitalia satisfactorily (&gt;2 times/day). 41% girls were aware of the fact that unhygienic use of pad could be a source of genital infection and 8% girls had associated vaginal discharge. Social restrictions during menses in the form of religious activities, drop out from school, avoiding certain foods etc were practiced in many families.Conclusion: Although the menstrual practices appear to be satisfactory in major percentage of girls but knowledge regarding menstrual hygiene is worrisome, as maximum girls are unaware of menarche and physiology of menstruation. Inclusion of such information in the school curriculum and wider coverage in mass media will help to bridge this gap.Keywords: Adolescence; hygiene; menstruation healt