Direct measurements of the convective recycling of the upper troposphere     

Bertram TH  Perring AE  Wooldridge PJ  Crounse JD  Kwan AJ  Wennberg PO  Scheuer E  Dibb J  Avery M  Sachse G  Vay SA  Crawford JH  McNaughton CS  Clarke A  Pickering KE  Fuelberg H  Huey G  Blake DR  Singh HB  Hall SR  Shetter RE  Fried A  Heikes BG  Cohen RC 《Science (New York, N.Y.)》2007,315(5813):816-820

We present a statistical representation of the aggregate effects of deep convection on the chemistry and dynamics of the upper troposphere (UT) based on direct aircraft observations of the chemical composition of the UT over the eastern United States and Canada during summer. These measurements provide unique observational constraints on the chemistry occurring downwind of convection and the rate at which air in the UT is recycled. These results provide quantitative measures that can be used to evaluate global climate and chemistry models.  相似文献   

KOI-126: a triply eclipsing hierarchical triple with two low-mass stars     

Carter JA  Fabrycky DC  Ragozzine D  Holman MJ  Quinn SN  Latham DW  Buchhave LA  Van Cleve J  Cochran WD  Cote MT  Endl M  Ford EB  Haas MR  Jenkins JM  Koch DG  Li J  Lissauer JJ  MacQueen PJ  Middour CK  Orosz JA  Rowe JF  Steffen JH  Welsh WF 《Science (New York, N.Y.)》2011,331(6017):562-565

The Kepler spacecraft has been monitoring the light from 150,000 stars in its primary quest to detect transiting exoplanets. Here, we report on the detection of an eclipsing stellar hierarchical triple, identified in the Kepler photometry. KOI-126 [A, (B, C)], is composed of a low-mass binary [masses M(B) = 0.2413 ± 0.0030 solar mass (M(⊙)), M(C) = 0.2127 ± 0.0026 M(⊙); radii R(B) = 0.2543 ± 0.0014 solar radius (R(⊙)), R(C) = 0.2318 ± 0.0013 R(⊙); orbital period P(1) = 1.76713 ± 0.00019 days] on an eccentric orbit about a third star (mass M(A) = 1.347 ± 0.032 M(⊙); radius R(A) = 2.0254 ± 0.0098 R(⊙); period of orbit around the low-mass binary P(2) = 33.9214 ± 0.0013 days; eccentricity of that orbit e(2) = 0.3043 ± 0.0024). The low-mass pair probe the poorly sampled fully convective stellar domain offering a crucial benchmark for theoretical stellar models.  相似文献   

Heat tolerance in Brazilian sheep: Physiological and blood parameters   总被引：1，自引：1，他引：0  

Concepta McManus  Giane Regina Paludo  Helder Louvandini  Rosilene Gugel  Luiz Cláudio Bastos Sasaki  Samuel Rezende Paiva 《Tropical animal health and production》2009,41(1):95-101

Thirty Santa Ines adult, non-lactating, non-pregnant ewes, ten with a brown coat, ten black coated and ten white coated, as well as ten Bergamasca and ten of mixed breed were used to evaluate the effect of climate on physiological and blood parameters in sheep. Two sample collections were taken (6 am and 2 pm) on six days. Sweating rate (SR), heart (HR) and breathing rates (BR), complete hemogram, rectal (RT) and skin temperatures (ST) were measured. Variance analyses were carried out using SAS®. In general, there were significant differences between animals due to skin type, time and day of collection. White coated animals showed lower HR, BR and RT, with afternoon parameters higher than morning. Correlations between HR, BR, RT, SR and ST were medium and positive. Correlations between physiological and blood traits were in general negative and medium. Packed Cell Volume (PCV), total plasma proteins, red blood cell count and hemoglobin concentration had high positive correlations between each other. The first two autovectors explained 49% of variation between traits. White coated Santa Ines animals were shown to be better adapted to climatic conditions in Central Brazil and wool sheep more affected by heat.  相似文献   

Ethyl hexanoate transfer modeling in carrageenan matrices for determination of diffusion and partition properties     

Juteau-Vigier A  Atlan S  Deleris I  Guichard E  Souchon I  Trelea IC 《Journal of agricultural and food chemistry》2007,55(9):3577-3584

Aroma compound properties in food matrices, such as volatility and diffusivity, have to be determined to understand the effect of composition and structure on aroma release and perception. This work illustrates the use of mass transfer modeling to identify diffusion and partition properties of ethyl hexanoate in water and in carrageenan matrices with various degrees of structure. The comparison of results obtained with a diffusive model to those obtained with a convective model highlights the importance of considering the appropriate transfer mechanism. Modeling of the preliminary experimental steps ensures correct estimation of the conditions for the main aroma release step. The obtained values of partition and diffusion coefficients are in agreement with those found in the literature (either experimentally determined or predicted by theoretical equations) and demonstrate that the structure level of carrageenan matrices has little influence on diffusion properties of ethyl hexanoate (less than 20%).  相似文献   

Postnatal changes in circulating concentrations of growth hormone, somatomedin C and thyroid hormones in pigs     

Colin G. Scanes  Douglas Lazarus  Samuel Bowen  Frances C. Buonomo  Rex L. Gilbreath 《Domestic animal endocrinology》1987,4(4):253-257

Plasma concentrations of growth hormone (GH), somatomedin (SmC), thyroxine (T₄) and triiodothyronine (T₃) were determined from birth to post weaning in pigs (Yorkshires). Plasma samples were obtained from the smallest, median and largest piglet from 11 litters. No differences in the circulating concentrations of any of the hormones were observed between piglets of different sizes. However, there were changes in circulating concentrations of hormones during postnatal development. Plasma concentrations of GH decreased between 2 and 8 to 10 days of age. A progressive increase in the circulating concentrations of SmC was observed with concentrations rising (3.83-fold between 2 days and 40 days of age). Plasma concentrations of T₄ and T₃ were maximal at 23 and 16 days of age, respectively.  相似文献   

What is the ecological footprint of aquaculture after 5 decades of competition between mangrove conservation and shrimp farm development?     

Samuel A. Ofori  Sunanda K. A. Kodikara  Loku P. Jayatissa  Sanduni K. Madarasinghe  T. W. G. F. Mafaziya Nijamdeen  Farid Dahdouh-Guebas 《水产资源保护:海洋与淡水生态系统》2023,33(1):15-28

1. Among the several threats to the conservation of mangrove ecosystems in most South Asian countries, shrimp farming is predominant. Since the introduction of shrimp farming in Sri Lanka in the 1980s, mangroves on the island’s north-western coast have been continually cleared to create new shrimp farms, leading to a decline in the social-ecological services provided by the mangrove ecosystems.
2. Using aerial (1973) and satellite (1996–2020) images, this study assessed areal changes in mangroves and shrimp farms in the Pambala-Chilaw lagoon complex and Ihala Mahawewa, as well as the ecological footprint of shrimp farming in the study area.
3. Mangroves around the Chilaw lagoon had decreased in areal extent by 45% from 1973 to 2020 of which 92% of this change was attributed to shrimp farming. There was, however, a decrease in the areal extent of shrimp farms from 2001 to 2020, and a corresponding increase in mangroves from 2006 to 2020.
4. The ecological footprint of shrimp farming was assessed by comparing the expected surface ratios with those recorded for shrimp farms with mangroves and surface water bodies in the study area from 1973 to 2020. The results showed that the current shrimp farming was unsustainable (i.e. high ecological footprint).
5. While the results support the current view that there is cause for cautious optimism with mangrove conservation (as evidenced by an increase in mangrove areal extent), it also reveals that semi-intensive shrimp farming in Sri Lanka and probably other similar tropical countries is unsustainable.
6. If immediate actions such as effective regulation of shrimp farming activities and mangrove restoration are not taken, the mangrove ecosystem will continue to decline.

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Habitat partitioning among three predatory fish in a temperate reservoir     

Samuel Westrelin  Julien Cucherousset  Romain Roy  Laurence Tissot  Frdric Santoul  Christine Argillier 《Ecology of Freshwater Fish》2022,31(1):129-142

The diversity of predatory species plays a key role in ecosystem functioning but our understanding of the mechanisms underlying their coexistence is limited, particularly in freshwater ecosystems. Northern pike Esox lucius, European perch Perca fluviatilis and pikeperch Sander lucioperca are three widespread predatory species in European lakes, where they often coexist. As potential competitors, we hypothesised that partitioning habitat is a determinant of species coexistence. This was tested by quantifying the variability of their habitat use in tracking adult individuals in the Bariousses reservoir (France, 86.6 ha, mean depth 7.1 m). Specifically, we investigated their distribution along the littoral–pelagic and depth axes along the daily cycle and across seasons. From littoral to pelagic waters were first found pike, then perch and finally pikeperch. Pike was the closest to the surface while pikeperch was the deepest. This general pattern was, however, variable across seasons with the three species located in the upper layer in summer during reservoir stratification. Individuals were more evenly distributed along the littoral–pelagic axis and closer to the bottom when water was mixing (autumn, winter). In summer, perch used more intensively in the pelagic zone during the daytime. Other species did not show any diel change of habitats. Our results highlighted that species coexistence is associated with habitat partitioning among these three predators, with perch showing a more variable behaviour regarding habitat characteristics. Now more than ever, in the context of global change which modifies habitats, it is of crucial importance to understand the coexistence mechanisms of species that shape ecosystems.  相似文献   

Phylogeography and conservation gaps of Musa balbisiana Colla genetic diversity revealed by microsatellite markers     

Mertens  Arne  Bawin  Yves  Vanden Abeele  Samuel  Kallow  Simon  Swennen  Rony  Vu  Dang Toan  Vu  Tuong Dang  Minh  Ho Thi  Panis  Bart  Vandelook  Filip  Janssens  Steven B. 《Genetic Resources and Crop Evolution》2022,69(7):2515-2534

Genetic Resources and Crop Evolution - Collection and storage of crop wild relative (CWR) germplasm is crucial for preserving species genetic diversity and crop improvement. Nevertheless, much of...  相似文献