4 research outputs found
Public Relations and Customer Service
This paper discover the PR roles in the customer relation issues, the purpose and benefit, what is the tools for PR. Also, it aims to investigate how you can people evaluate department of PR (customer serves) and the plan of PR. the literature review included background about the main work of public relation and customer service duties. Researchers used the survey methods and collect the data in the UAE PR offices. They found that there is a relationship between PR services and satisfying public needs
Nitrate pollution of ground water and impacts of nitrogenous fertilizers and irrigation on dynamics of NO3-N movement in soils of Punjab, Pakistan
Increase in N application rates may eventually raise the potential groundwater N-pollution. This survey study was conducted by Soil Chemistry Section, ISCES to assess the NO3 contents of soil from 0 to 120 cm depth with different intervals. For this purpose, the soil and water samples were collected from Okara, Vehari Sialkot, Chiniot, Hafizabad, Sahiwal and Multan districts. The results showed that nitrate leaching occurred but it is only up to 2 feet soil depth. The NO3-N contents were maximum at two upper depths (i.e. 0-30 cm and 30-60 cm) and then decreased gradually downward. The highest average NO3-N content was found at 0-30 cm soil depth and the lowest were found at 90-120 cm. The data also revealed that mean NO3-N content at 0-30, 30-60, 60-90 and 90-120 cm depths were 16.85±4.05, 15.21±4.77, 9.94±3.36 and 6.54±2.62 mg kg-1, respectively, whereas NO3-N content at same depths were ranged from 11.50-26.20, 6.53-21.15, 5.24-16.12, 1.45-9.36 mg kg-1, respectively. The results regarding underground water samples (tube well) from the same sites from all the three districts showed that NO3 were found in all the water samples but it was only in traces and their concentration were not much higher to create the health hazardous problem owing to NO3 leaching. The data showed that the highest NO3 contents did not exceed than 8.61 and 10.6 ppm in Multan and Sahiwal districts respectively, which were much lower than permissible limit i.e. 50 ppm (FAO). Similarly, the nitrate content in underground water are well below the maximum admissible limit of WHO i.e. 50 mg L-1
A precursor plateau and pre-maximum [O II] emission in the superluminous SN2019szu: a pulsational pair-instability candidate
We present a detailed study on SN2019szu, a Type I superluminous supernova at z = 0.213 that displayed unique photometric and spectroscopic properties. Pan-STARRS and ZTF forced photometry show a pre-explosion plateau lasting ∼40 d. Unlike other SLSNe that show decreasing photospheric temperatures with time, the optical colours show an apparent temperature increase from ∼15 000 to ∼20 000 K over the first 70 d, likely caused by an additional pseudo-continuum in the spectrum. Remarkably, the spectrum displays a forbidden emission line (likely attributed to λλ7320,7330) visible 16 d before maximum light, inconsistent with an apparently compact photosphere. This identification is further strengthened by the appearances of [O III] λλ4959, 5007, and [O III] λ4363 seen in the spectrum. Comparing with nebular spectral models, we find that the oxygen line fluxes and ratios can be reproduced with ∼0.25 M⊙ of oxygen-rich material with a density of
. The low density suggests a circumstellar origin, but the early onset of the emission lines requires that this material was ejected within the final months before the terminal explosion, consistent with the timing of the precursor plateau. Interaction with denser material closer to the explosion likely produced the pseudo-continuum bluewards of ∼5500 Å. We suggest that this event is one of the best candidates to date for a pulsational pair-instability ejection, with early pulses providing the low density material needed for the formation of the forbidden emission line, and collisions between the final shells of ejected material producing the pre-explosion plateau
The birth of a relativistic jet following the disruption of a star by a cosmological black hole
A black hole can launch a powerful relativistic jet after it tidally disrupts a star. If this jet fortuitously aligns with our line of sight, the overall brightness is Doppler boosted by several orders of magnitude. Consequently, such on-axis relativistic tidal disruption events have the potential to unveil cosmological (redshift z > 1) quiescent black holes and are ideal test beds for understanding the radiative mechanisms operating in super-Eddington jets. Here we present multiwavelength (X-ray, UV, optical and radio) observations of the optically discovered transient AT 2022cmc at z = 1.193. Its unusual X-ray properties, including a peak observed luminosity of ≳1048 erg s−1, systematic variability on timescales as short as 1,000 s and overall duration lasting more than 30 days in the rest frame, are traits associated with relativistic tidal disruption events. The X-ray to radio spectral energy distributions spanning 5–50 days after discovery can be explained as synchrotron emission from a relativistic jet (radio), synchrotron self-Compton (X-rays) and thermal emission similar to that seen in low-redshift tidal disruption events (UV/optical). Our modelling implies a beamed, highly relativistic jet akin to blazars but requires extreme matter domination (that is, a high ratio of electron-to-magnetic-field energy densities in the jet) and challenges our theoretical understanding of jets