Weighing the galactic disc using the Jeans equation: lessons from simulations

Using three-dimensional stellar kinematic data from simulated galaxies, we examine the efficacy of a Jeans equation analysis in reconstructing the total disk surface density, including the dark matter, at the ‘Solar’ radius. Our simulation data set includes galaxies formed in a cosmological context using state-of-the-art high-resolution cosmological zoom simulations, and other idealized models. The cosmologically formed galaxies have been demonstrated to lie on many of the observed scaling relations for late-type spirals, and thus offer an interesting surrogate for real galaxies with the obvious advantage that all the kinematical data are known perfectly. We show that the vertical velocity dispersion is typically the dominant kinematic quantity in the analysis, and that the traditional method of using only the vertical force is reasonably effective at low heights above the disk plane. At higher heights the inclusion of the radial force becomes increasingly important. We also show that the method is sensitive to uncertainties in the measured disk parameters, particularly the scalelengths of the assumed double exponential density distribution, and the scalelength of the radial velocity dispersion. In addition, we show that disk structure and low number statistics can lead to significant errors in the calculated surface densities. Finally, we examine the implications of our results for previous studies of this sort, suggesting that more accurate measurements of the scalelengths may help reconcile conflicting estimates of the local dark matter density in the literature

Plasma splashing from Al and Cu materials induced by and Nd : YAG pulsed laser

Plasma splashing from Al and Cu target materials and the growth of thin films on Cu and Al, respectively, has been studied using a Q-switched Nd:YAG laser with a 1064-nm, 80-mJ, 8-ns pulse width as the source of ablation. The target kept rotating and the substrate, Cu for Al and vice versa, was placed at an angle of 15° with respect to the beam axis. During the laser-matter interaction, the targets absorbed thermal energy within the thermal region depth of 4.7 (1.1) nm, yielding an ablated skin depth of 6.7 (4.2) nm. The surface morphology of the exposed targets was studied by analyzing SEM micrographs obtained using a ZEISS SUPRA 35 VP. The obtained results are explained on the basis of different sputtering/ablation mechanisms. Comparatively severe damage forming a bigger crater is seen on the Al target surface in contrast to the crater on the Cu surface. This observation is correlated with the blustering effect and/or debris formation. Energy dispersive spectroscopy (EDX) of the substrates yielded the deposition of micrometric grain-size particle

Young stars in the periphery of the Large Magellanic Cloud

Despite their close proximity, the complex interplay between the two Magellanic Clouds, the Milky Way, and the resulting tidal features, is still poorly understood. Recent studies have shown that the Large Magellanic Cloud (LMC) has a very extended disk strikingly perturbed in its outskirts. We search for recent star formation in the far outskirts of the LMC, out to ~30 degrees from its center. We have collected intermediate-resolution spectra of thirty-one young star candidates in the periphery of the LMC and measured their radial velocity, stellar parameters, distance and age. Our measurements confirm membership to the LMC of six targets, for which the radial velocity and distance values match well those of the Cloud. These objects are all young (10-50 Myr), main-sequence stars projected between 7 and 13 degrees from the center of the parent galaxy. We compare the velocities of our stars with those of a disk model, and find that our stars have low to moderate velocity differences with the disk model predictions, indicating that they were formed in situ. Our study demonstrates that recent star formation occurred in the far periphery of the LMC, where thus far only old objects were known. The spatial configuration of these newly-formed stars appears ring-like with a radius of 12 kpc, and a displacement of 2.6 kpc from the LMC's center. This structure, if real, would be suggestive of a star-formation episode triggered by an off-center collision between the Small Magellanic Cloud and the LMC's disk.Comment: Accepted for publication in MNRA

Nanostructural and optical properties of hierarchical ZnO grown via hydrothermal method

A simple hydrothermal method was employed to synthesize 3D hierarchical ZnO nanorods deposited on Si (100) substrate at different growth temperatures (110 and 90oC) within 3 h. The structure, mode and composition of hierarchical ZnO nanorods were investigated by XRD, FESEM and EDX spectroscopy. The polycrystalline ZnO nanostructures products were indexed as hexagonal wurtzite structured, while the morphology was urchin like ZnO nanorods with different aspect ratio of nanorods and stoichiometric. The photoluminescence (PL) properties were studied of as-grown ZnO samples dependent on various growth temperatures. The PL results after UV excitation source were shown a single broad Vis emission peak for both samples with absents of UV emission peak. The emission edge of Vis peak was exhibited blue-shift due to increase temperature growth, and that suggest enhancement in hierarchical ZnO nanorods crystallinity. Oxygen deficiency is evidence on the creation various defects types in hierarchical ZnO nanorods. It is responsible on Vis emission bands. The results demonstrate promising future for the hierarchal ZnO nanostructure which could be applied in optoelectronics and gas sensing

Growth and characterization of spherical cinnamon nanoparticles: Evaluation of antibacterial efficacy

Organic nanoparticles with controlled properties are advantageous for diversified biomedical and pharmacological applications. Cinnamon nanoparticles (CNPs) being bioactive and nontoxic can be effective antibacterial agents. Driven by this idea, we prepared spherical CNPs using pulse laser ablation in liquid (PLAL) technique and characterized these NPs. A pure cinnamon target immersed in liquid ethanol (5 mL) was ablated using Q-switched Nd:YAG pulse laser of varying energy (30–180 mJ). Laser energy dependent structure, morphology and optical properties of the as-grown CNPs were determined. Furthermore, the antibacterial activity of such CNPs against four bacterial strains (Escherichia coli, Staphylococcus aureus, Bacillus subtilis and Pseudomonas aeruginosa) was evaluated using agar well diffusion and optical density measurements. These CNPs were demonstrated to be beneficial for the development of antibacterial drugs and food processing

Estimating logged-over lowland rainforest aboveground biomass in Sabah, Malaysia using airborne LiDAR data

Unprecedented deforestation and forest degradation in recent decades have severely depleted the carbon storage in Borneo. Estimating aboveground biomass (AGB) with high accuracy is crucial to quantifying carbon stocks for Reducing Emissions from Deforestation and Forest Degradation-plus implementation (REDD+). Airborne Light Detection and Ranging (LiDAR) is a promising remote sensing technology that provides fine-scale forest structure variability data. This paper highlights the use of airborne LiDAR data for estimating the AGB of a logged-over tropical forest in Sabah, Malaysia. The LiDAR data was acquired using an Optech Orion C200 sensor onboard a fixed wing aircraft. The canopy height of each LiDAR point was calculated from the height difference between the first returns and the Digital Terrain Model (DTM) constructed from the ground points. Among the obtained LiDAR height metrics, the mean canopy height produced the strongest relationship with the observed AGB. This single-variable model had a root mean squared error (RMSE) of 80.02 t ha-1 or 22.31% of the mean AGB, which performed exceptionally when compared with recent tropical rainforest studies. Overall, airborne LiDAR did provide fine-scale canopy height measurements for accurately and reliably estimating the AGB in a logged-over forest in Sabah, thus supporting the state's effort in realizing the REDD+ mechanism

The effects of the ambient liquid medium on the ablation efficiency, size and stability of silver nanoparticles prepared by pulse laser ablation in liquid technique

Silver (Ag) nanoparticles (NPs) were synthesized by pulsed laser (Nd:YAG, 1064 nm) ablation of individual target in various solutions. The influence of deionized water (DIW), ethanol and Polyvinylpyrrolidone (PVP) as ambient medium on the fundamental aspects such as ablation efficiency, particle size and stability of Ag NPs was studied. UV-vis spectrophotometer and transmission electron microscopy (TEM) were used to study the optical characterization and morphological analysis of all the synthesized samples, respectively. Preparation in DIW was carried out as a reference sample. The experiments demonstrated that ablation efficiency and stability of NPs in ethanol medium are lowest than those prepared in PVP medium and the reference sample. PVP medium led to higher stability, lower ablation efficiency and finer average particle size compared to reference sample

Discovery of a rapidly pulsating subdwarf B star candidate in omega Cen

We report the discovery of the first variable extreme horizontal branch star in a globular cluster (omega Cen). The oscillation uncovered has a period of 114 s and an amplitude of 32 mmags. A comparison between horizontal branch models and observed optical colours indicates an effective temperature of 31,500+-6,300 K for this star, placing it within the instability strip for rapidly oscillating B subdwarfs. The time scale and amplitude of the pulsation detected are also in line with what is expected for this type of variable, thus strengthening the case for the discovery of a new subdwarf B pulsator.Comment: 5 pages, 7 figures; accepted for publication in A&

Antecedents and Consequence of Murabaha Funding in Islamic Banks of Indonesia

As Islam supports fair trade, the Murabaha is the most popular and most common mode of Islamic financing. It is a contract of sale between the bank and its client for the sale of goods at a price plus an agreed profit margin for the bank. The contract involves the purchase of goods by the bank which then sells them to the client at an agreed mark-up. While their characteristics and values are unique, they are also subject to conventional measurement of efficacies. This study investigates how the primary health predictors of conventional banks under the Basel III regime could provide a positive means to assess the Murabaha funding and subsequently secure long-term profitability. This study constructed a path analysis (from 120 databases) to assess whether Islamic banks’ leverage and capital adequacy may alter the Murabaha funding and increase stock equity directly and indirectly. The research findings are mixed where leverage does not alter the Murabaha funding but only affects the profitability; besides, capital adequacy increases the outgoing funding significantly but does not increase stock equity. Murabaha funding is essential to Islamic bank equity. This study implies Murabaha funding are expensed, despite increasing debts in Islamic bank