Predicting moisture content and density distribution of Scots pine by microwave scanning of sawn timber II: evaluation of models generated on a pixel level     

Nils Lundgren  Olle Hagman  Jan Johansson 《Journal of Wood Science》2006,52(1):39-43

The purpose of this study was to use images from a microwave sensor on a pixel level for simultaneous prediction of moisture content and density of wood. The microwave sensor functions as a line-scan camera with a pixel size of 8mm. Boards of Scots pine (Pinus sylvestris), 25 and 50mm thick, were scanned at three different moisture contents. Dry density and moisture content for each pixel were calculated from measurements with a computed tomography scanner. It was possible to create models for prediction of density on a pixel level. Models for prediction of moisture content had to be based on average values over homogeneous regions. Accuracy will be improved if it is possible to make a classification of knots, heartwood, sapwood, etc., and calibrate different models for different types of wood. The limitations of the sensor used are high noise in amplitude measurements and the restriction to one period for phase measurements.  相似文献   

Maritime Halophyte Species from Southern Portugal as Sources of Bioactive Molecules     

Maria Jo?o Rodrigues  Katkam N. Gangadhar  Catarina Vizetto-Duarte  Sileshi G. Wubshet  Nils T. Nyberg  Luísa Barreira  Jo?o Varela  Luísa Custódio 《Marine drugs》2014,12(4):2228-2244

Extracts of five halophytes from southern Portugal (Arthrocnemum macrostachyum, Mesembryanthemum edule, Juncus acutus, Plantago coronopus and Halimione portulacoides), were studied for antioxidant, anti-inflammatory and in vitro antitumor properties. The most active extracts towards the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical were the methanol extracts of M. edule (IC₅₀ = 0.1 mg/mL) and J. acutus (IC₅₀ = 0.4 mg/mL), and the ether extracts of J. acutus (IC₅₀ = 0.2 mg/mL) and A. macrostachyum (IC₅₀ = 0.3 mg/mL). The highest radical scavenging activity (RSA) against the 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radical was obtained in the ether extract of J. acutus (IC₅₀ = 0.4 mg/mL) and H. portulacoides (IC₅₀ = 0.9 mg/mL). The maximum total phenolic content (TPC) was found in the methanol extract of M. edule (147 mg gallic acid equivalents (GAE)/g) and in the ether extract of J. acutus (94 mg GAE/g). Significant decreases in nitric oxide (NO) production were observed after incubation of macrophages with lipopolysaccharide (LPS) and the chloroform extract of H. portulacoides (IC₅₀ = 109 µg/mL) and the hexane extract of P. coronopus (IC₅₀ = 98.0 µg/mL). High in vitro cytotoxic activity and selectivity was obtained with the ether extract of J. acutus. Juncunol was identified as the active compound and for the first time was shown to display selective in vitro cytotoxicity towards various human cancer cells.  相似文献   

Use of dietary supplements in Denmark is associated with health and former smoking     

Knudsen VK  Rasmussen LB  Haraldsdóttir J  Ovesen L  Bülow I  Knudsen N  Jørgensen T  Laurberg P  Perrild H 《Public health nutrition》2002,5(3):463-468

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Element (Ag, Cd, Cu, Pb, Sb, Tl and Zn), element ratio and lead isotope profiles in a sediment affected by a mining operation episode during the late 19th century     

Mattias Bäckström  Hanna Bohlin  Stefan Karlsson  Nils G. Holm 《Water, air, and soil pollution》2006,177(1-4):285-311

Mining operations at Mårsätter in 1877–81 resulted in increased metal loading to a small lake, notably as sulphidic tailings. The event is taken as an opportunity to study the present environmental impact of a historical single major metal release. Lake water and four sediment cores were sampled and analysed for principal and trace elements in solid and aqueous phases as well as general hydrochemical conditions. Chronologies were determined from ²⁰⁶Pb/²⁰⁷Pb ratios and historical records. Ordinary sedimentation after the event has lead to that the tailings are found as a distinct layer at a depth of 18–22 cm in the sediment. The layer is characterized by elevated metal concentrations in the solid and pore water phases, respectively, circum neutral pH and sulphate concentrations below detection. Geochemical modelling indicated a preference for carbonate equilibrium in the waste while sulphides prevailed above it. It is concluded that the growth of the ordinary sediment on top of the waste has lead to a physicochemical barrier that seals of the waste from the overlying sediment. Chemical or physical rupture of the barrier will release the metals to downstream regions. According to the chronologies at least three sources have contributed to the present elevated levels of metals, in additions to the release of tailings. Copper from a historical blast furnace prior to the event at Mårsätter, transport from mineralized parts of the watershed and release of contaminated water from present mining operations maintain elevated levels of notably zinc, silver, cadmium and lead. At present less than 10% of the lead content at the sediment/water interface comes from atmospheric deposition. Increased levels of antimony and thallium were not observed prior to ca 1950.  相似文献   

Predictive thresholds for plague in Kazakhstan     

Davis S  Begon M  De Bruyn L  Ageyev VS  Klassovskiy NL  Pole SB  Viljugrein H  Stenseth NC  Leirs H 《Science (New York, N.Y.)》2004,304(5671):736-738

In Kazakhstan and elsewhere in central Asia, the bacterium Yersinia pestis circulates in natural populations of gerbils, which are the source of human cases of bubonic plague. Our analysis of field data collected between 1955 and 1996 shows that plague invades, fades out, and reinvades in response to fluctuations in the abundance of its main reservoir host, the great gerbil (Rhombomys opimus). This is a rare empirical example of the two types of abundance thresholds for infectious disease-invasion and persistence- operating in a single wildlife population. We parameterized predictive models that should reduce the costs of plague surveillance in central Asia and thereby encourage its continuance.  相似文献   

Neuroscience. SPARring with spines     

Meyer G  Brose N 《Science (New York, N.Y.)》2003,302(5649):1341-1344

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The genome of the diatom Thalassiosira pseudonana: ecology, evolution, and metabolism     

Armbrust EV  Berges JA  Bowler C  Green BR  Martinez D  Putnam NH  Zhou S  Allen AE  Apt KE  Bechner M  Brzezinski MA  Chaal BK  Chiovitti A  Davis AK  Demarest MS  Detter JC  Glavina T  Goodstein D  Hadi MZ  Hellsten U  Hildebrand M  Jenkins BD  Jurka J  Kapitonov VV  Kröger N  Lau WW  Lane TW  Larimer FW  Lippmeier JC  Lucas S  Medina M  Montsant A  Obornik M  Parker MS  Palenik B  Pazour GJ  Richardson PM  Rynearson TA  Saito MA  Schwartz DC  Thamatrakoln K  Valentin K  Vardi A  Wilkerson FP  Rokhsar DS 《Science (New York, N.Y.)》2004,306(5693):79-86

Diatoms are unicellular algae with plastids acquired by secondary endosymbiosis. They are responsible for approximately 20% of global carbon fixation. We report the 34 million-base pair draft nuclear genome of the marine diatom Thalassiosira pseudonana and its 129 thousand-base pair plastid and 44 thousand-base pair mitochondrial genomes. Sequence and optical restriction mapping revealed 24 diploid nuclear chromosomes. We identified novel genes for silicic acid transport and formation of silica-based cell walls, high-affinity iron uptake, biosynthetic enzymes for several types of polyunsaturated fatty acids, use of a range of nitrogenous compounds, and a complete urea cycle, all attributes that allow diatoms to prosper in aquatic environments.  相似文献   

Dynamics of public attitudes toward bears and the role of bear hunting in Croatia     

Aleksandra Maji?  Agnese Marino Taussig de Bodonia  ?uro Huber  Nils Bunnefeld 《Biological conservation》2011,144(12):3018-3027

Successful carnivore conservation depends on public attitudes and acceptance levels of carnivores, and these are likely to change as circumstances change. Attitude studies repeated in time that can demonstrate such change are rare. Our study surveyed Croatian rural inhabitants in 2002 and in 2008 and analyzed their responses to detect a change in attitudes toward brown bears (Ursus arctos) over time. Important developments occurring in Croatia at the time of our research included a more centralized and more clearly defined bear management strategy, and an increase in the bear population. We constructed models to explain respondent’s value orientations, their level of perceived threat and their acceptance capacity for bears. Findings show that while value orientations and the overall level of perceived threat did not change over time, bear acceptance capacity was reduced. This suggests that the increase in the bear population and perhaps the more centralized bear management reduced respondents’ willingness to accept a larger bear population. We conclude that continuous public involvement in bear management is essential in order to maintain a feeling of control over the bear among the local population. Furthermore we argue that hunting is an important form of public involvement in the region, serving to reinforce existence and bequest values of the bear and increase its public acceptance.  相似文献   

Metallspeziierung in Bodenlösungen mittels Dialysen- und Ionenaustauscherverfahren     

G. Dietze  Nils Knig 《植物养料与土壤学杂志》1988,151(4):243-250

Metal speciation in soil solution by dialysis-and ion exchange resin procedures A graduated separation procedure was applied for determining ionic and organic species of main and transition elements in soil solutions. Dialysis of the samples against pure water was found to be an appropriate method for analyzing weak complexes. Ionic forms could be differentiated from soluble strong organic complexes by varying electrolyte concentrations and cation exchange resin. The results of experiments which cation exchange resin in direct contact with the sample (column-mode and batch- mode) were compared with those from dialysis. Thus, three types of element forms could be distinguished: such forms, which could be characterized as inorganically bound ones (K, Na), such elements, which were only weakly bound to organic compounds in order to maintain electrical neutrality (Ca, Mg, Mn, Zn, Cd) and such elements, which were strongly complexed by organic molecules to a high extent (Cu, Cr, Pb, Fe, Al).  相似文献   

Hydrochemical processes at a pristine site in nord-trøndelag,mid-Norway     

Robert C. Ferrier  Hamish A. Anderson  John D. Miller  T. A. Bruce Walker  Nils Christophersen 《Water, air, and soil pollution》1992,62(3-4):281-302

A detailed study of hydrochemical processes associated with vegetation and soils was undertaken at a pristine site in mid-Norway. Inputs to the site during snow-free periods showed a marked seasonality with excess sulphate concentrations in rainfall only during the summer months. However, this represented a small fraction of total annual loading and there was a dominant influence of sea salt deposition. Site vegetation modified the chemistry of water reaching the soil surface, and this also showed a marked seasonal response. The pristine nature of this site results in the soils retaining acid-soluble components which may have been eluted from impacted sites. In the soils, the extractable aluminium remains largely (70%) in the organic bound forms. The contribution of different sources of water in affecting streamwater output quality at this site are discussed.  相似文献