Shell Crossing Singularities in Quasi-Spherical Szekeres Models

We investigate the occurrence of shell crossing singularities in quasi-spherical Szekeres dust models with or without a cosmological constant. We study the conditions for shell crossing singularity both from physical and geometrical point of view and they are in agreement.Comment: 10 latex pages, RevTex style, no figure

Origin of the anomalous magnetic circular dichroism spectral shape in ferromagnetic (Ga,Mn)As: Impurity bands inside the band gap

The electronic structure of a prototype dilute magnetic semiconductor (DMS), Ga1-xMnxAs, is studied by magnetic circular dichroism (MCD) spectroscopy. We prove that the optical transitions originated from impurity bands cause the strong positive MCD background. The MCD signal due to the E0 transition from the valence band to the conduction band is negative indicating that the p-d exchange interactions between the p-carriers and d-spin is antiferromagnetic. The negative E0 MCD signal also indicates that the hole-doping of the valence band is not so large as previously assumed. The impurity bands seem to play important roles for the ferromagnetism of Ga1-xMnxAs.Comment: 13 pages, 3 figure

Density Evolution in the New Modified Chaplygin Gas Model

In this paper, we have considered new modified Chaplygin gas (NMCG) model which interpolates between radiation at early stage and $\Lambda$CDM at late stage. This model is regarded as a unification of dark energy and dark matter (with general form of matter). We have derived the density parameters from the equation of motion for the interaction between dark energy and dark matter. Also we have studied the evolution of the various components of density parameters.Comment: 6 Latex pages, 4 figures, RevTex styl

High pressure synchrotron x-ray diffraction study of the Mn0.94Ti0.06CoGe alloy

High pressure x-ray diffraction studies up to 10.4 GPa were performed on the Mn0.94Ti0.06CoGe alloy using synchrotron radiation with a diamond anvil cell. No structural phase transitions occurred in the entire range of our measurements. Unit cell parameters were determined up to 10.4 GPa and the calculated unit cell volumes were found to be well represented by a third order Birch-Murnaghan equation of state. The bulk modulus determined from the pressure - volume data was found to be, B0 = 231.72 ± 7.79 GPa. This study, employing high resolution synchrotron x-rays has helped clarify the behaviour of the Mn0.94Ti0.06CoGe alloy under high pressure

A New Variable Modified Chaplygin Gas Model Interacting with Scalar Field

In this letter we present a new form of the well known Chaplygin gas model by introducing inhomogeneity in the EOS. This model explains $\omega=-1$ crossing. Also we have given a graphical representation of the model using $\{r,s\}$ parameters. We have also considered an interaction of this model with the scalar field by introducing a phenomenological coupling function and have shown that the potential decays with time.Comment: 7 pages, 3 figure

Potential of relative humidity as a proxy of air temperature in developing passive and adaptive building fa\ue7ades with bio-based responsive materials

There has been significant development in thermo-responsive materials for drug delivery and bio-medical use; some are bio-based. However, the use of thermo-responsive bio-based materials in the built environment, especially on the building fa\ue7ade, is almost non-existent due to complexities including difficulties manufacturing in bulk, cost and durability to weathering. On the other hand, humidity-responsive materials such as wood are abundant and are used in buildings globally. Furthermore, new bio-based humidity-responsive materials such as bacterial cellulose (BC) and natural fibres have the potential for building applications. In this study, we hypothesised that if there was a relationship between the relative humidity and air temperature in a location, humidity-responsive materials could be used to develop passive and adaptive building fa\ue7ades, which would indirectly respond to temperature. Here, we selected two sites (New Delhi, India and Newcastle upon Tyne, UK) with temperate climates — according to the K\uf6ppen-Geiger system— to analyse the relationship between relative humidity and air temperature from 37 years (1985-2022) of weather data and typical meteorological year (TMY) climate data for 2004-2018. This relationship assessment used the Pearson correlation (coefficient and p-value) analysis. Our results showed a strong and statistically significant negative correlation between the relative humidity and air temperature in all months in 37 years in New Delhi, with the strongest correlation in the summer and monsoon months. However, the correlation was strong only in some summer months for Newcastle upon Tyne. We concluded that humidity-responsive bio-based materials have the potential to be used to actuate passive and adaptive building fa\ue7ades in New Delhi (for all-year-round use) and Newcastle (only during summer), which respond indirectly to external temperature

Bio-jaali: Passive building skin with mycelium for climate change adaptation to extreme heat

Climate change induced global warming and frequent extreme heat events have become common recently, increasing the ownership and operation of active cooling, particularly in cities and megacities. To reduce the dependency on active cooling, in this study, we aimed to re-design ‘Jaali’— perforated screens made of bricks and sandstones to cool the incoming air inspired by historical building use— with bio-based materials such as mycelium. We hypothesised that ‘Bio-jaali’ would ventilate and reduce the indoor temperature reducing energy demand for cooling. For the climatic context, we selected the temperate climate of New Delhi. We used climatic data analysis and performance-based dynamic environmental simulations with Designbuilder and Energy Plus to evaluate the effect of Bio-jaali on the indoor operative temperature in a single-zone naturally ventilated indoor office space. The simulation results showed sandstone Jaali reduced the annual average indoor operative temperature by 5.2%, whereas Bio-jaali were able to provide a reduction of 3.0% compared to the base case. Furthermore, the seasonal analysis showed that Bio-jaali reduced the summer indoor operating temperature by decreasing heat gain from outdoor heat, particularly during daytime and increased indoor temperature during winter by reducing heat loss, demonstrating its potential for year-round usage

Polar delivery of Legionella type IV secretion system substrates is essential for virulence

A recurrent emerging theme is the targeting of proteins to subcellular microdomains within bacterial cells, particularly to the poles. In most cases, it has been assumed that this localization is critical to the protein’s function. Legionella pneumophila uses a type IVB secretion system (T4BSS) to export a large number of protein substrates into the cytoplasm of host cells. Here we show that the Legionella export apparatus is localized to the bacterial poles, as is consistent with many T4SS substrates being retained on the phagosomal membrane adjacent to the poles of the bacterium. More significantly, we were able to demonstrate that polar secretion of substrates is critically required for Legionella’s alteration of the host endocytic pathway, an activity required for this pathogen’s virulence