Magnetic properties of natural Mn-oxides

Summary The paper is devoted to the study of the magnetic properties, of the volume magnetic susceptibility in a weak magnetic field, of the specific magnetic susceptibility in a strong magnetic field, of natural remanent magnetization and its stability in A.C. fields, and of the temperature dependence of magnetic susceptibility of natural Mn-oxides. Samples of pyrolusite, polianite, manganite, hausmannite, psilomelan and wad from different localities all over the world were studied; the measured values are statistically treated so that the given values are valid in general. Hausmannite displayed typical values of the magnetic susceptibility, different from the values of the other Mn-oxides. In general, many natural Mn-oxides contain heterogeneous admixtures of Fe-oxides, which are responsible for their ferromagnetic properties. A high degree of magnetic hardness, predetermining the minerals for palaeomagnetic research, was proved with many of the natural Mn-oxides.     

The Landscape of Diversity in U.S. Higher Education Geography

Palynological analyses were completed for the A and B horizons of a forested Mollic Hapludalf to determine type, amount, and distribution of pollen and spores within the soil solum. Hypotheses regarding the origin of pollen and the mechanisms of its movement within soil bodies are also advanced. Pollen downwash within the mineral soil seems to be very slow and confined to the uppermost porous and most homogenized part of the solum. The predominance of non-arboreal pollen at depth was believed to be a result of deposition with the loess parent material. High arboreal pollen frequencies in the upper horizons coupled with increases in non-arboreal types at depth indicate gradual ongoing mixing from the present vegetation into the soil.     

Technical, economics and environmental analysis of semi-intensive shrimp (Litopenaeus vannamei) farming in Sonora, Sinaloa and Nayarit states, at the east coast of the Gulf of California, México

In Mexico shrimp pond aquaculture is the main activity and contributes with 45.9% of the total fisheries volume and 74.3% of gross profit generated by the national products, being Sonora, Sinaloa and Nayarit in the east coast of the Gulf of California the states generating around 70% of region gross profit. The main species cultivated is the white shrimp Litopenaeus vannamei, and for this reason academic and government sector devoted much attention in this species, however, still researching on economic feasibility is scarce and needed. In this paper, the technical, economics, production and environment parameters of 80 semi-intensive commercial in these states are analyzed and discussed. The results showed the main external constraints affecting short and long run farm performance. The overall observations pointed out that there is an increase on yield and income when shrimp farms invest in higher quality inputs such as equipment and technology for more efficiency in using water, use of certified post-larvae and better design of farm facility. Nevertheless, further research is needed to adjust shrimp production strategies to specific farm requirement by investing in premium quality inputs. Furthermore, the most serious threat from shrimp aquaculture is the potential effect on water quality and the infrastructure associated, that having more serious effects on the environment, particularly in the coastal wetlands. The economic and the environment care must be driven to lead a more sustainable scenario.     

Geophysical evidence of the Eastern Marginal Fault of the Cheb Basin (Czech Republic)

The western part of the Bohemian Massif hosts an intersection of two regional fault zones, the SW-NE trending Oh?e/Eger Graben and the NNW-SSE trending Mariánské Lázně Fault, which has been reactivated several times in the geological history and controlled the formation of the Tertiary Cheb Basin. The broader area of the Cheb Basin is also related to permanent seismic activity of M_L 3+ earthquake swarms. The Eastern Marginal Fault of the Cheb Basin (northern segment of the Mariánské Lázně Fault) separates the basin sediments and underlying granites in the SW from the Kru?né Hory/Erzgebirge Mts. crystalline unit in the NE. We describe a detailed geophysical survey targeted to locating the Eastern Marginal Fault and determining its geometry in the depth. The survey was conducted at the Kopanina site near the Nový Kostel focal zone, which shows the strongest seismic activity of the whole Western Bohemia earthquake swarm region. Complex geophysical survey included gravimetry, electrical resistivity tomography, audiomagnetotellurics and seismic refraction. We found that the rocks within the Eastern Marginal Fault show low resistivity, low seismic velocity and density, which indicates their deep fracturing, weathering and higher water content. The dip of the fault in shallow depths is about 60° towards SW. At greater depths, the slope turns to subvertical with dip angle of about 80°. Results of geoelectrical methods show blocky fabric of the Cheb Basin and deep weathering of the granite bedrock, which is consistent with geologic models based on borehole surveys.     

Frequency and variability of missing tree rings along the stems of Pinus halepensis and Pinus pinea from a semiarid site in SE Spain

We studied the occurrence of missing rings (MR) around and along the stems of three Pinus halepensis and three Pinus pinea trees growing in a semiarid Mediterranean site in SE Spain. Tree-ring analyses were performed along 8 radii on stem discs taken at 1 m distances from the base to the top of the trees. The tree rings analysed showed that 19% were missing in P. halepensis and 10% in P. pinea. MR were recorded in 61% of P. halepensis and 24% of P. pinea in the years analysed. Dry conditions from January to May and high late winter to spring temperatures seem to be the main climatic elements promoting MR in both species. In our research into P. halepensis, the frequency of MR gradually decreased from the bottom upward, but no such pattern was observed in P. pinea. Most tree rings were missing only locally (LMR), indicating that wood formation occurred every year in at least some part of a tree, and the tree rings were often discontinuous around and along the stem. Since the frequency of LMR greatly varies around and along the stem, our results suggest that serial sectioning along the stem provides more information on wood formation and responses of trees to environment than studying the samples at breast height only. The disadvantage of the technique is that, as in our study case, research is based on a limited sample size, since it requires destructive sampling with tree felling, which is not usually possible or desirable on highly vulnerable semiarid forest ecosystems.     

The dynamics of tourist excursion ratios in Slovakia show caves from 2000 to 2014

Show caves are one of the most important targets in developing local ecotourism strategies. This work focuses on a tourism visit rate incidence through an Attractiveness Index concerning 12 selected show caves in Slovakia. Our study focuses on visitor counts published from 2000 to 2014. A set of eight criteria were selected in order to analyse and determine the appeal that each cave may have for visitors. Establishing the “degree” of appeal as an indicator of the tourism and geographic absolute attractiveness value is based on a principal components factor analysis; the resultant single factor was correlated with our selected criteria. We find a strong correlation between touristic cave attractiveness and cave locations, ease of cave passage access (vehicle and trail) infrastructures, cave location in main tourism regions, and the growth of urban areas as they encroach on show cave locations. Similar studies in valorization of show caves tourism have not been attempted in Slovakia or Eastern Europe. The data and result from this study are also clearly important from a managerial perspective. This general framework could be easily expanded to include additional attributes that might be relevant for other market segments or other vacation experiences.     

Dating carbonate rocks with in-situ produced cosmogenic Be: Why it often fails

Surface exposure dating of carbonate rocks using cosmogenic ¹⁰Be is problematic. We have performed step-wise leaching of calcite-rich samples in order to investigate the reasons for this. Results on different grain size fractions clearly indicate the source of atmospheric ¹⁰Be is clay. We demonstrate that partial-leaching procedures, which result in moderate pH levels will not release ¹⁰Be (in-situ produced or atmospheric) due to the instant re-absorption on grain surfaces. By contrast, under strongly acidic conditions, all absorbed ¹⁰Be is leached from aluminosilicates giving abnormally high ¹⁰Be concentrations and consequently exposure ages that are too old. Dating is only possible if samples do not contain any clay minerals or if they can be removed prior to carbonate dissolution.     

Vlf experiment with the interkosmos-5 satellite

Summary The Interkosmos5 VLF experiment consisted of a spectrum analyser with twelve narrow-band channels and broadband measurements between0.07 and20 kHz using an analogue telemetry with a tape recorder on board. The apparatus used in the experiment is shortly described, some examples ofVLF phenomena observed are given and a review of all analogue data recorded is shown in a graphical calendar.