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Variations in the spectral content of volcano seismicity related to changes in volcanic activity are commonly identified manually in spectrograms. However, long time series of monitoring data at volcano observatories require tools to facilitate automated and rapid processing. Techniques such as self-organizing maps (SOM) and principal component analysis (PCA) can help to quickly and automatically identify important patterns related to impending eruptions. For the first time, we evaluate the performance of SOM and PCA on synthetic volcano seismic spectra constructed from observations during two well-studied eruptions at Klauea Volcano, Hawai'i, that include features observed in many volcanic settings. In particular, our objective is to test which of the techniques can best retrieve a set of three spectral patterns that we used to compose a synthetic spectrogram. We find that, without a priori knowledge of the given set of patterns, neither SOM nor PCA can directly recover the spectra. We thus test hierarchical clustering, a commonly used method, to investigate whether clustering in the space of the principal components and on the SOM, respectively, can retrieve the known patterns. Our clustering method applied to the SOM fails to detect the correct number and shape of the known input spectra. In contrast, clustering of the data reconstructed by the first three PCA modes reproduces these patterns and their occurrence in time more consistently. This result suggests that PCA in combination with hierarchical clustering is a powerful practical tool for automated identification of characteristic patterns in volcano seismic spectra. Our results indicate that, in contrast to PCA, common clustering algorithms may not be ideal to group patterns on the SOM and that it is crucial to evaluate the performance of these tools on a control dataset prior to their application to real data. [ABSTRACT FROM AUTHOR]

The article presents a study which examines the contribution of very small glaciers to the total mass of ice around the world. The study uses number-size scaling and volume-area scaling to estimate the total ice volume, and calculate the potential error in total volume in relation with any lower-bound threshold in glacier size. Results show that one percent and sometimes 10% errors in the total ice volume are small ice masses.

Sunflower is a plant species with a prominent period of seed dormancy. Physiological maturation period can be accelerated under laboratory conditions using methods for breaking seed dormancy such as: previous cooling at 5-10°C, previous heating at 30-35°C, gibberellic acid treatment, KNO3, ethrel, etc. The aim of this study was to determine the duration of seed dormancy period of different sunflower hybrids and parent lines produced in Serbia, and to determine which of the methods for breaking seed dormancy gives the best results. Studies were carried out on five commercial sunflower hybrids and their parental components. Seed germination was determined after harvesting using standard laboratory methods and tetrazolium tests. The following methods were used for seed dormancy breaking: low temperature treatment of 5- 10°C, high temperature treatment of 30-35°C, and treatment with gibberellic acid. The tests were performed in the period of 30, 50, and 90 days after harvesting. The application of gibberellic acid method gave the lowest values of seed germination, while statistical significant differences between the control and method of low and high temperatures were not found. Sunflower hybrids Sremac, Duško, NS-H-111, Velja and Branko, as well as the female lines of hybrid NS-H-111, and male lines of hybrids Sremac and Velja had no prominent seed dormancy 30 days after harvesting. Seed dormancy in female lines of hybrids Sremac, Duško, Velja and Branko and male lines of hybrids Duško, NS-H-111 and Branko was decreased 90 days after storage, but it was not completely removed. [ABSTRACT FROM AUTHOR]

Sunflower is an important source of oil and proteins necessary for development of healthy humans. By producing sunflower seeds, the main gains a possibility to use oil and proteins in different forms. The content of the observed parameters varies and depends on numerous factors. Environmental factors, the choice of genotypes and measures that apply during the production of seed all influence the content of oil and proteins in sunflower seed, as well as seed germination, one of the most important seed characteristics. Based on the results obtained by comparing the observed parameters, further interdependence (correlation) of the observed parameters of sunflower seed quality is established. Significant differences were determined between localities in which sunflower seed was produced. During the research, significant positive and negative correlations were found between the observed parameters of sunflower seed quality. [ABSTRACT FROM AUTHOR]

To harvest a sunflower crop, it is important to bring moisture content, i.e., moisture level in leaves, stems, heads and seed, to a level that permits normal work of combine harvester. In 2003, an experiment was established at Rimski Šančevi experiment field to determine optimum time for desiccation of sunflower. The experiment included 10 parental components, which are grown at large area for F1 seed production. A comparative study showed that oil content, protein content and seed viability change with seed maturity. The experiment indicated that the values of oil and protein contents and seed viability stop increasing when the average seed moisture reaches 24%. This moment was concluded to represent the optimum time for desiccation of sunflower seed crop. [ABSTRACT FROM AUTHOR]

Seed quality is a complex character that is determined by a large number of parameters. Because of this, knowing the interrelationships among these parameters is of utmost importance, not only from the point of view of plant selection but also from the standpoint of crop production itself. The objective of this study was to investigate the influence of production season and production region ( i.e., environmental conditions) on quality parameters and yield of sunflower hybrid seed. The study was conducted on the seed of the hybrids NS-H-111 and Rimi that had been produced at sites located in Serbia and Ukraine. The following traits were studied: germinability, 1000-seed weight, husk content, protein content, and seed yield per hectare. All of the studied parameters were affected the most by the genotype itself. Germinability ranged from 87.75% in NS-H-111 produced in Serbia to 95.50% in Rimi produced in Ukraine. The 1000-seed weight was greatly influenced by the production area. All of the studied factors individually produced highly significant differences in husk content, which ranged from 20.35% in NS-H-111 to 31.40% in Rimi. Seed protein content was highly significantly affected by all the factors studied. On average, genotype had the greatest effect on seed yield as well, with the difference in yield between the hybrids (833.0 kg) being highly significant. On the average, looking at the production season and area, differences were observed with regard to seed yield, but those were not statistically significant. [ABSTRACT FROM AUTHOR]

Most glaciers and ice caps (GIC) are out of balance with the current climate. To return to equilibrium, GIC must thin and retreat, losing additional mass and raising sea level. Because glacier observations are sparse and geographically biased, there is an under sampling problem common to all global assessments. Here, we further develop an assessment approach based on accumulation-area ratios (AAR) to estimate committed mass losses and analyze the under sampling problem. We compiled all available AAR observations for 144 GIC from 1971 to 2010, and found that most glaciers and ice caps are farther from balance than previously believed. Accounting for regional and global undersampling errors, our model suggests that GIC are committed to additional losses of 32±12% of their area and 38±16% of their volume if the future climate resembles the climate of the past decade. These losses imply global mean sea-level rise of 163±69 mm, assuming total glacier volume of 430mm sea-level equivalent. To reduce the large uncertainties in these projections, more long-term glacier measurements are needed in poorly sampled regions. [ABSTRACT FROM AUTHOR]

A three-year experiment (2008, 2009, 2010) on twenty sunflower hybrids grown in 13 (2010) to 15 (2009, 2008) locations in the region of Vojvodina and central Serbia was carried out in order to study GEI (genotype × environment interaction) on oil yield and stability of hybrids using non-parametric measures of stability. The non-parametric test indicated the presence of significant crossover interaction [G(E) and E(G)]. Non-parametric measures Si(1)and Si(2)were used to determine stability of sunflower hybrids. The level of association among stability measures was assessed using Sperman's rank correlation. Significant differences in rank stability among 20 sunflower hybrids grown in 13 (2010) or 15 (2009, 2008) locations were found. According to non-parametric stability parameters Si(1)and Si(2), hybrids Baća and Vranac were most stable in all locations. Baća also had high oil yield in 2008 and 2009. In 2010 two new hybrids (NS-H-6612, NS-H-2069) were high yielding and stable for oil yield. Hybrid NS-H-111 was also stable in all locations in 2009 and 2010 and its oil yield was above average. The Spearman's rank correlation between non-parametric stability parameters, showed highly significant (P<0.01) rank correlations between Si(1)and Si(2), indicating that the two measures were similar in classifying the hybrids according to their stability under different environmental (location) conditions. Non-parametric measures of stability, based on ranks, could be recommended to agronomists and plant breeders. [ABSTRACT FROM AUTHOR]

Hybrid sunflower seed, regularly protected with chemicals, is used for sowing in the second or the third year if not used in the first year after production. In that case, it is stored in warehouses, and the length of storage period may significantly affect the quality of seeds. An experiment was conducted in Laboratory for Seed Testing of Institute of Field and Vegetable Crops in Novi Sad, in order to examine the effect of storage period on germination of treated sunflower seeds of three commercial hybrids of the Novi Sad Institute. The seed was treated with fungicides - metalaxyl and fludioxonil, as well as with insecticides - thiamethoxam and imidacloprid, while untreated seeds served as control. The sowing was repeated throughout the year, at three-month intervals. The obtained results indicated that, on average, the hybrid Sremac had the highest (94.61%), and the hybrid Šumadinac the lowest seed germination (90.29%). After one year of storage, seed germination declined significantly. All three hybrids treated with fungicides and the control had a significantly higher germination than hybrids treated with insecticides. This regularity was not evident right after the treatment - it became noticeable during the storage. [ABSTRACT FROM AUTHOR]