Environmental-Economic Model of Developing Composters in Parks, Protected Areas and City Limits in the Republic of Serbia

This paper deals with advantages of development of a new model of composter which would be exploited in parks and other protected areas of local self-governments of the Republic of Serbia. The impact of protected areas on ecological systems would not be adverse; contrary to that, there would be numerous advantages both in environmental and economic terms. The authors point out only some of them, such as: reduction in transport costs of bulky green waste to disposal areas, reduction in air pollution in the protected areas of towns caused by the use of transport vehicles in the traditional model of green waste disposal, reduced labour, elimination of allergy-causing plants by their mechanical elimination. In addition to all mentioned advantages, a useful product would be made after a year, i.e. compost, the use of which would yield environmental and economic benefits to local self-governments if they introduce this model of composter development in the protected areas

Probing Reionization with Quasar Spectra: the Impact of the Intrinsic Lyman-alpha Emission Line Shape Uncertainty

Arguably the best hope of understanding the tail end of the reionization of the intergalactic medium (IGM) at redshift z > 6 is through the detection and characterization of the Gunn-Peterson (GP) damping wing absorption of the IGM in bright quasar spectra. However, the use of quasar spectra to measure the IGM damping wing requires a model of the quasar's intrinsic Lyman-alpha emission line. Here we quantify the uncertainties in the intrinsic line shapes, and how those uncertainties affect the determination of the IGM neutral fraction. We have assembled a catalog of high-resolution HST spectra of the emission lines of unobscured low-redshift quasars, and have characterized the variance in the shapes of their lines. We then add simulated absorption from the high-redshift IGM to these quasar spectra in order to determine the corresponding uncertainties in reionization constraints using current and future samples of z > 6 quasar spectra. We find that, if the redshift of the Lyman-alpha emission line is presumed to coincide with the systemic redshift determined from metal lines, the inferred IGM neutral fraction is systematically biased to low values due to a systematic blueshift of the Lyman-alpha line relative to the metal lines. If a similar blueshift persists in quasars at z > 6, this bias strengthens previous claims of a significant neutral hydrogen fraction at z ~ 6. This technique is capable of making a robust distinction between a highly ionized (x_IGM ~ 10^-3) and a neutral (x_IGM = 1) IGM with even a few bright quasars.Comment: accepted for publication in MNRAS, full tables available at http://www.astro.columbia.edu/~roban