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51.
52.
Jürgen Aosaar Mats Varik Krista Lõhmus Ivika Ostonen Hardo Becker Veiko Uri 《European Journal of Forest Research》2013,132(5-6):737-749
In the Northern and Baltic countries, grey alder is a prospective tree species for short-rotation forestry. Hence, knowledge about the functioning of such forest ecosystems is critical in order to manage them in a sustainable and environmentally sound way. The 17-year-long continuous time series study is conducted in a grey alder plantation growing on abandoned agricultural land. The results of above- and below-ground biomass and production of the 17-year-old stand are compared to the earlier published respective data from the same stand at the ages of 5 and 10 years. The objectives of the current study were to assess (1) above-ground biomass (AGB) and production; (2) below-ground biomass: coarse root biomass (CRB), fine root biomass (FRB) and fine root production (FRP); (3) carbon (C) and nitrogen (N) accumulation dynamics in grey alder stand growing on former arable land. The main results of the 17-year-old stand were as follows: AGB 120.8 t ha?1; current annual increment of the stem mass 5.7 t ha year?1; calculated CRB 22.3 t ha?1; FRB 81 ± 10 g m?2; nodule biomass 31 ± 19 g m?2; fine root necromass 11 ± 2 g m?2; FRP 53 g DM m?2 year?1; fine root turnover rate 0.54 year?1; and fine root longevity 1.9 years. FRB was strongly correlated with the stand basal area and stem mass. Fine root efficiency was the highest at the age of 10 years; at the age of 17 years, it had slightly reduced. Grey alder stand significantly increased N and Corg content in topsoil. The role of fine roots for the sequestration of C is quite modest compared to leaf litter C flux. 相似文献
53.
Lesmes U Beards EJ Gibson GR Tuohy KM Shimoni E 《Journal of agricultural and food chemistry》2008,56(13):5415-5421
This study probed the possible effects of type III resistant starch (RS) crystalline polymorphism on RS fermentability by human gut microbiota and the short chain fatty acids production in vitro. Human fecal pH-controlled batch cultures showed RS induces an ecological shift in the colonic microbiota with polymorph B inducing Bifidobacterium spp. and polymorph A inducing Atopobium spp. Interestingly, polymorph B also induced higher butyrate production to levels of 0.79 mM. In addition, human gut simulation demonstrated that polymorph B promotes the growth of bifidobacteria in the proximal part of the colon and double their relative proportion in the microbiota in the distal colon. These findings suggest that RS polymorph B may promote large bowel health. While the findings are limited by study constraints, they do raise the possibility of using different thermal processing to delineate differences in the prebiotic capabilities of RS, especially its butryrogenicity in the human colon. 相似文献
54.
Because of the lack of a large animal hospital in Israel, and the need to provide radiology service to equine and bovine patients, a complete radiology mobile laboratory for field work was built. The laboratory was constructed in a van-type automobile and is equipped with a condenser-discharge x-ray unit, a tabletop automatic processor, and a dark room facility. The qualities of each of the components and the operation of the laboratory are discussed. 相似文献
55.
Steinman A Orgad U Sutton GA 《The Canadian veterinary journal. La revue veterinaire canadienne》2000,41(11):861-863
Wet gangrene developed in all 4 limbs following repair of a rupture in the lower urinary tract in a 2-week-old foal. Dehydration and hypoxemia are suspected as the inciting causes of the necrosis. 相似文献
56.
Trends in the use of conservation tillage in US agriculture 总被引:1,自引:0,他引:1
N. D. Uri 《Soil Use and Management》1998,14(2):111-116
Abstract. In 1996 conservation tillage was used on nearly 36% of the cropped area of the USA. This level has remained relatively unchanged over the past few years. The use of conservation tillage varied by crop and was dependent on site-specific factors including soil type, topsoil depth, and local climatic conditions. A number of economic, demographic, geographic, and policy factors have affected the adoption of conservation tillage. While it was not possible to quantify exactly the impact of these factors, it was clear that management complexities and profitability are key factors impeding an increase. 相似文献
57.
Nutrient use efficiency and harvest index of cassava decline as fertigation solution concentration increases 下载免费PDF全文
John Okoth Omondi Naftali Lazarovitch Shimon Rachmilevitch Steve Boahen Pheneas Ntawuruhunga Eldad Sokolowski Uri Yermiyahu 《植物养料与土壤学杂志》2018,181(5):644-654
Response of cassava (Manihot esculenta Crantz) to fertigation as a form of nutrient delivery is unknown. The objectives of this study were to establish a balanced nutrition and to enhance agronomic nutrient use efficiency (ANUE) of cassava under fertigation. This study was conducted in the greenhouse and in the field. In both, the results showed a similar trend. There were six fertigation concentrations and three cassava varieties, selected for their duration of growth in the field. Shoot biomass of the long‐duration variety (Nalumino) was the highest, even though its dry root yield was the lowest (10.18 t ha?1) among the varieties. In contrast, the medium‐duration variety (Kampolombo) produced the highest dry root yield (20.34 t ha?1) and a lower shoot biomass. The highest root yield of the shortest‐duration variety (Mweru) was achieved at 200 mg N, 30 mg P, and 200 mg K L?1 (155.0, 23.3, 155.0 kg N, P, K ha?1), while Nalumino's was at 70 mg N, 7 mg P, and 70 mg K L?1 (54.3, 5.4, 54.3 kg N, P, K ha?1). ANUE and harvest index of these varieties declined as the fertigation concentrations increased. Additionally, the correlation between concentrations of N in the youngest fully expanded leaf (YFEL) blades and dry root yields was the lowest (R2 = 0.5488), whereas P and K were R2 = 0.7237 and R2 = 0.8006, respectively, an indication that nutrient concentrations in the leaf, especially N, cannot easily be used to predict root yield. When cassava reaches nutrient sufficiency, mainly N, its accumulation in the leaf continues without significant increase in the root yield. 相似文献
58.
Mukamel R Gelbard H Arieli A Hasson U Fried I Malach R 《Science (New York, N.Y.)》2005,309(5736):951-954
Functional magnetic resonance imaging (fMRI) is an important tool for investigating human brain function, but the relationship between the hemodynamically based fMRI signals in the human brain and the underlying neuronal activity is unclear. We recorded single unit activity and local field potentials in auditory cortex of two neurosurgical patients and compared them with the fMRI signals of 11 healthy subjects during presentation of an identical movie segment. The predicted fMRI signals derived from single units and the measured fMRI signals from auditory cortex showed a highly significant correlation (r = 0.75, P < 10(-47)). Thus, fMRI signals can provide a reliable measure of the firing rate of human cortical neurons. 相似文献
59.
Keren K Krueger M Gilad R Ben-Yoseph G Sivan U Braun E 《Science (New York, N.Y.)》2002,297(5578):72-75
Recent advances in the realization of individual molecular-scale electronic devices emphasize the need for novel tools and concepts capable of assembling such devices into large-scale functional circuits. We demonstrated sequence-specific molecular lithography on substrate DNA molecules by harnessing homologous recombination by RecA protein. In a sequence-specific manner, we patterned the coating of DNA with metal, localized labeled molecular objects and grew metal islands on specific sites along the DNA substrate, and generated molecularly accurate stable DNA junctions for patterning the DNA substrate connectivity. In our molecular lithography, the information encoded in the DNA molecules replaces the masks used in conventional microelectronics, and the RecA protein serves as the resist. The molecular lithography works with high resolution over a broad range of length scales from nanometers to many micrometers. 相似文献
60.
The combination of their electronic properties and dimensions makes carbon nanotubes ideal building blocks for molecular electronics. However, the advancement of carbon nanotube-based electronics requires assembly strategies that allow their precise localization and interconnection. Using a scheme based on recognition between molecular building blocks, we report the realization of a self-assembled carbon nanotube field-effect transistor operating at room temperature. A DNA scaffold molecule provides the address for precise localization of a semiconducting single-wall carbon nanotube as well as the template for the extended metallic wires contacting it. 相似文献