149 research outputs found

    Galactic Punctuated Equilibrium: How to Undermine Carter's Anthropic Argument in Astrobiology

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    We investigate a new strategy which can defeat the (in)famous Carter's "anthropic" argument against extraterrestrial life and intelligence. In contrast to those already considered by Wilson, Livio, and others, the present approach is based on relaxing hidden uniformitarian assumptions, considering instead a dynamical succession of evolutionary regimes governed by both global (Galaxy-wide) and local (planet- or planetary system-limited) regulation mechanisms. This is in accordance with recent developments in both astrophysics and evolutionary biology. Notably, our increased understanding of the nature of supernovae and gamma-ray bursts, as well as of strong coupling between the Solar System and the Galaxy on one hand, and the theories of "punctuated equilibria" of Eldredge and Gould and "macroevolutionary regimes" of Jablonski, Valentine, et al. on the other, are in full accordance with the regulation- mechanism picture. The application of this particular strategy highlights the limits of application of Carter's argument, and indicates that in the real universe its applicability conditions are not satisfied. We conclude that drawing far-reaching conclusions about the scarcity of extraterrestrial intelligence and the prospects of our efforts to detect it on the basis of this argument is unwarranted.Comment: 3 figures, 26 page

    A contribution to the data on tench (Tinca tinca L., Cyprinidae, pisces) distribution in Serbia

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    The studies on the ichthyofauna of Serbia that have been conducted so far indicate the sporadic tench (Tinca tinca L.) presence in typical habitats. The hydroenvironmental conditions necessary for the survival of this fish species are highly variable and, generally, are more favourable in the northern part of the country (the Vojvodina Province). Although the tench presence has been registered at over 30 sites, there is a tendency of a decrease in population abundance. This is due to the reduction of the surface area of the macrophyte-covered flood zones induced by the damming and regulation of rivers, high water level fluctuations, and water amount reduction in the majority of watercourses, a massive increase in the number of allochthonous phytofagous species, reservoir sediment deposition, water quality deterioration and other factors. The tench conservation status in Serbia is officially designated as Low Risk - Least Concern. It may be transferred to a higher category if the tendency towards deterioration of survival conditions for the species should continue

    CHEMICAL EVALUATION OF AUTOCHTHONOUS VARIETY 'PROKUPAC' RED WINE WITH THE ADDITION OF SELECTED AROMATIC HERBS

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    The quality parameters and chemical composition (total phenolics, total flavonoids and total anthocyanins) of the red wine obtained from the autochthonous variety 'Prokupac' (Vitis vinifera L.) with the addition of the selected aromatic herbs (Pimpinella anisum L., Cinnamomum zeylanicum, Artemisia absinthium and Glycyrrhiza glabra) were examined in two consequtive vintages (2013-2014). The differences in contents of total extract, reducing sugars and ash between the studied samples were observed, but with no statistical significance between both examined years and analyzed wines. 'Prokupac' red wines with the addition of aromatic herbs stood out with significantly higher contents of total phenolics (371.4-594.3 mg GAE L-1) and total flavonoids (136.2-243.2 mg CTE L-1) while lower total anthocyanins content was noticed, when compared to 'Prokupac' red wine used as control (p<0.05). The unfavourable weather conditions in the vintages 2013 and 2014, reflected notably on the quality of the obtained wine. To analyze the correlations between wine quality parameters and the similarity of individual wine samples, Principal Component Analysis (PCA) was used

    Factors affecting elimination of polycyclic aromatic hydrocarbons from traditional smoked common carp meat

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    Smoking techniques have been progressively improved and different procedures have been developed in different regions for treating fish. In these times, the technology is mainly used for enrichment of fish with specific taste and odour, to extend the shelf-life of these perishable products and appearance required widely on the market. A lot of chemical contaminants such as polycyclic aromatic hydrocarbons (PAHs) are formed during the combustion of fuel in the smoking process. PAHs are a group of compounds that have been the subject of great concern in the recent years due to their toxic, mutagenic and/or carcinogenic potentials to humans. These fact can have a significant impact on the acceptance of these products by consumers. In this review article, the objective is to describe factors affecting elimination of polycyclic aromatic hydrocarbons from traditional smoked common carp meat

    Galactic Gradients, Postbiological Evolution and the Apparent Failure of SETI

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    Motivated by recent developments impacting our view of Fermi's paradox (absence of extraterrestrials and their manifestations from our past light cone), we suggest a reassessment of the problem itself, as well as of strategies employed by SETI projects so far. The need for such reevaluation is fueled not only by the failure of searches thus far, but also by great advances recently made in astrophysics, astrobiology, computer science and future studies, which have remained largely ignored in SETI practice. As an example of the new approach, we consider the effects of the observed metallicity and temperature gradients in the Milky Way on the spatial distribution of hypothetical advanced extraterrestrial intelligent communities. While, obviously, properties of such communities and their sociological and technological preferences are entirely unknown, we assume that (1) they operate in agreement with the known laws of physics, and (2) that at some point they typically become motivated by a meta-principle embodying the central role of information-processing; a prototype of the latter is the recently suggested Intelligence Principle of Steven J. Dick. There are specific conclusions of practical interest to be drawn from coupling of these reasonable assumptions with the astrophysical and astrochemical structure of the Galaxy. In particular, we suggest that the outer regions of the Galactic disk are most likely locations for advanced SETI targets, and that intelligent communities will tend to migrate outward through the Galaxy as their capacities of information-processing increase, for both thermodynamical and astrochemical reasons. This can also be regarded as a possible generalization of the Galactic Habitable Zone, concept currently much investigated in astrobiology.Comment: 30 pages, 2 figure

    Astrobiological Complexity with Probabilistic Cellular Automata

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    Search for extraterrestrial life and intelligence constitutes one of the major endeavors in science, but has yet been quantitatively modeled only rarely and in a cursory and superficial fashion. We argue that probabilistic cellular automata (PCA) represent the best quantitative framework for modeling astrobiological history of the Milky Way and its Galactic Habitable Zone. The relevant astrobiological parameters are to be modeled as the elements of the input probability matrix for the PCA kernel. With the underlying simplicity of the cellular automata constructs, this approach enables a quick analysis of large and ambiguous input parameters' space. We perform a simple clustering analysis of typical astrobiological histories and discuss the relevant boundary conditions of practical importance for planning and guiding actual empirical astrobiological and SETI projects. In addition to showing how the present framework is adaptable to more complex situations and updated observational databases from current and near-future space missions, we demonstrate how numerical results could offer a cautious rationale for continuation of practical SETI searches.Comment: 37 pages, 11 figures, 2 tables; added journal reference belo

    Laudatores Temporis Acti, or Why Cosmology is Alive and Well - A Reply to Disney

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    A recent criticism of cosmological methodology and achievements by Disney (2000) is assessed. Some historical and epistemological fallacies in the said article have been highlighted. It is shown that---both empirically and epistemologically---modern cosmology lies on sounder foundations than it is portrayed. A brief historical account demonstrates that this form of unsatisfaction with cosmology has had a long tradition, and rather meagre results in the course of the XX century.Comment: 11 pages, no figures; a criticism of astro-ph/0009020; Gen. Rel. Grav., accepted for publicatio

    Comparative Profiling of Microplastics in Differently sized Manila Clams from South Korea by Nile Red Staining and μFTIR

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    The high bioavailability of microplastics (MP) to marine biota has led to the contamination of seafood products. The safety of shellfish as food has become questionable due to the potential health risks associated with MP. As such, microplastics ingestion by commonly consumed shellfish is being investigated. In this study, market samples of clams (Ruditapes philippinarum, n=101) from South Korea were segregated into two different sizes (small and large) and analysed for microplastics contamination. Using alkaline digestion, MP were extracted and subsequently quantified using two of the most commonly used techniques in the field- Nile red staining (NRS) and μFTIR imaging [1], [2]. With NRS, the small (n= 51) and large (n= 50) clams were analysed individually. On the other hand, 8 composite subsamples (30 small and 31 large clams) were subjected to μFTIR imaging. The average MP concentration based on NRS was 4.3 ± 5.2 MP/ g ww (wet weight of soft tissue) considering both small and large clams. In the subsamples, 3.2 ± 1.6 MP/ g ww and 3.8 ± 1.7 MP/g ww were detected based on μFTIR and NRS, respectively. NRS showed 18-75% higher MP quantity compared to μFTIR. This was considered to be a consequence of the co-staining of remnants of undigested biological which was confirmed by additional staining using DAPI. Due to this overestimation, only μFTIR data was utilized for the comparative analysis of the differently sized clams. The MP abundance in both groups was comparable, with the small and large clams having 2.7 ± 1.7 MP/g ww and 3.6 ± 1.6 MP/g ww, respectively. Similarly, there was no significant difference observed in the concentration of MP fibers and MP non-fibers. In the small clams, only PS (polystyrene) and PET (polyethylene terephthalate) were identified from the fibers. In contrast, PP (polypropylene), PS (polystyrene), PE, and PET were found from the fibers that came from the large clams. The same 4 synthetic polymers were detected from the non-fibers obtained from both groups. Overall, PS was the most prominent type, accounting for 35- 49% of total detected MP. In terms of MP size, 20-50μm was the most abundant followed by 50-100μm. Relative to the weight of the samples, the quantity of MP, classified according to size and polymer type, was similar in both groups. In summary, the size of the clams had no effect on the MP content as suggested by the analogous concentrations of MP with respect to shape, size, and polymer identity. In addition, despite the simplicity, low-cost, and growing popularity of NRS, this method should be used with caution due to its propensity to overestimate MP quantity
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