Soil CO<Subscript>2</Subscript>, CH<Subscript>4</Subscript> and N<Subscript>2</Subscript>O emissions from production fields with planted and remnant hedgerows in the Fraser River Delta of British Columbia     

Bryanna Thiel  Maja Krzic  Sarah Gergel  Christine Terpsma  Andrew Black  Rachhpal Jassal  Sean M. Smukler 《Agroforestry Systems》2017,91(6):1139-1156

Planting hedgerows on farm field edges can help mitigate greenhouse gas (GHG) emissions from agricultural landscapes by sequestering carbon (C) in woody biomass and in soil. Sequestration rates however, must be assessed in terms of their overall global warming potential (GWP) which must also consider GHG emissions. The objectives of this study were to (1) compare carbon dioxide (CO₂), methane (CH₄) and nitrous oxide (N₂O) emissions from two types of hedgerows and adjacent annual agricultural production fields, and 2) better understand how climate, soil properties and plant species configurations affect hedgerow GHG emissions. At eight study sites in the lower Fraser River delta of British Columbia, we measured emissions from soil in both planted (P-Hedgerow) and remnant hedgerows (R-Hedgerow), as well as in adjacent annual crop production fields over 1 year using a closed-static chamber method. CO₂ emissions were 59 % higher in P-Hedgerow than R-Hedgerow, yet there were no significant differences of relative emissions of CH₄ and N₂O. The environmental variables that explained the variation in emissions differed for the three GHGs. CO₂ emissions were significantly correlated with soil temperature. CH₄ and N₂O and emissions were marginally significantly correlated with soil organic carbon (SOC) and soil water-filled pore space (WFPS), respectively. Emissions were not significantly correlated with hedgerow plant species diversity. While hedgerows sequester carbon in their woody biomass, we demonstrated that it is critical to measure hedgerow emissions to accurately ascertain their overall GHG mitigation potential. Our results show that there are no CO₂e emission differences between the management options that plant new diverse hedgerows or conserve existing hedgerows.  相似文献   

Sleep Characterization at High Altitude     

Nicholas Kanaan  Caleb Phillips  Becky Higbee  David Pomeranz  Michael Shaheen  Kristin Fontes  Patrick Cain  Sean Wentworth  Carolyn Meyer  Grant Lipman 《The Forestry Chronicle》2017,28(4):366

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Haemodynamic effects of ATP in dogs during hypoxia-induced pulmonary hypertension     

B. Driessen  S.C. Haskins  P.J. Pascoe  L.D. Tripp  & J.A. Reitan 《Journal of veterinary pharmacology and therapeutics》1999,22(3):213-219

Pulmonary hypertension may result from an increase in vascular resistance caused by persistent hypoxia. We have investigated the effects of adenosine triphosphate (ATP), administered into the pulmonary artery, on haemodynamic changes occurring in anaesthetized adult dogs subjected to acute hypoxic pulmonary vasoconstriction. Hypoxia alone (ventilation with 10% O2/90% N2) caused significant increases in mean pulmonary arterial blood pressure (PAP), central venous pressure (CVP), and cardiac index (CI) by 71, 102 and 38%, respectively. ATP (0.03-3.0 micromol/kg/min approximately 0.02-1.65 mg/kg/min), when infused under hypoxic conditions, significantly reduced both mean PAP and systemic arterial blood pressure (ABP) in a dose-dependent manner. The maximum decrease in mean PAP amounted to 20%; mean ABP, on the other hand, was decreased by up to 52% (P<0.01). Heart rate, CI, CVP and pulmonary occlusion pressure were not dose-dependently affected by ATP. Our data indicate that while pulmonary arterial administration of ATP in mature dogs during hypoxic pulmonary hypertension causes dilation in the pulmonary vascular bed, it is even more effective in dilating the systemic vasculature. This result suggests a need for further evaluation and warrants cautious use of ATP in the treatment of hypoxic pulmonary hypertension in adult dogs.  相似文献   

Effects of intravenously administered glycopyrrolate in anesthetized horses.          下载免费PDF全文

D H Dyson  P J Pascoe    W N McDonell 《The Canadian veterinary journal. La revue veterinaire canadienne》1999,40(1):29-32

The purpose of this study was to determine the heart rate (HR) and blood pressure (BP) effect of glycopyrrolate in anesthetized horses with low HR (< or = 30 beats/min). The horses were randomly treated with glycopyrrolate (2.5 micrograms/kg body weight (BW)) or saline, intravenously (i.v.) (n = 17). If HR failed to increase (by > 5 beats/min within 10 min), glycopyrrolate (same dose) was administered. Heart rate increased by > 5 beats/min in 3 out of 9 horses following the initial glycopyrrolate treatment. Overall changes in HR and mean BP were not significantly different, while systolic and diastolic BP increased significantly (P < 0.025 using a Bonferroni corrected paired t-test). On the 2nd treatment, 3 out of 7 horses given 2.5 micrograms/kg BW glycopyrrolate, and 4 out of 5 horses given 5.0 micrograms/kg BW (total dose) showed an increase in heart rate of > 5 beats/min, which was significant. A significant increase in BP was produced following treatment with 2.5 micrograms/kg BW, but not following 5.0 micrograms/kg BW. A final increase in HR, of > 5 beats/min, was associated with a significant rise in BP (P < 0.05 using an unpaired t-test). In conclusion, an increase in HR can occur with 2.5 to 5.0 micrograms of glycopyrrolate/kg BW, i.v., and results in improvement in BP in anesthetized horses.  相似文献   

Serial exploitation of global sea cucumber fisheries     

Sean C Anderson  Joanna Mills Flemming  Reg Watson  Heike K Lotze 《Fish and Fisheries》2011,12(3):317-339

In recent decades, invertebrate fisheries have expanded in catch and value worldwide. One increasingly harvested group is sea cucumbers (class Holothuroidea), which are highly valued in Asia and sold as trepang or bêche‐de‐mer. We compiled global landings, economic data, and country‐specific assessment and management reports to synthesize global trends in sea cucumber fisheries, evaluate potential drivers, and test for local and global serial exploitation patterns. Although some sea cucumber fisheries have existed for centuries, catch trends of most individual fisheries followed boom‐and‐bust patterns since the 1950s, declining nearly as quickly as they expanded. New fisheries expanded five to six times faster in 1990 compared to 1960 and at an increasing distance from Asia, encompassing a global fishery by the 1990s. Global sea cucumber production was correlated to the Japanese yen at a leading lag. Regional assessments revealed that population declines from overfishing occurred in 81% of sea cucumber fisheries, average harvested body size declined in 35%, harvesters moved from near‐ to off‐shore regions in 51% and from high‐ to low‐value species in 76%. Thirty‐eight per cent of sea cucumber fisheries remained unregulated, and illegal catches were of concern in half. Our results suggest that development patterns of sea cucumber fisheries are largely predictable, often unsustainable and frequently too rapid for effective management responses. We discuss potential ecosystem and human community consequences and urge for better monitoring and reporting of catch and abundance, proper scientific stock assessment and consideration of international trade regulations to ensure long‐term and sustainable harvesting of sea cucumbers worldwide.  相似文献   

Abiotic persistence of atrazine and simazine in water     

Sean D W Comber 《Pest management science》1999,55(7):696-702

Hydrolysis and photolysis experiments have been undertaken to investigate the abiotic persistence of atrazine and simazine in a variety of waters. Hydrolysis only occurs to a significant extent at pH values at the lower limit of those found in the natural aquatic environment (pH 4.0 or less). Photolysis was initiated by a wide range of wavelengths in waters at pH 4.0, but only by more energetic wavelengths of less than 300 nm at higher pH values (pH 6 to 8). Based on these data, the aquatic half-life of atrazine and simazine in well-lit acidic upland waters will be typically six days. In lowland rivers with higher pH (7 to 8.5), these triazines are likely to exhibit half-lives of months rather than days. In groundwaters, atrazine and simazine will have half-lives in the order of years, due to the exceedingly slow rate of hydrolysis. © 1999 Society of Chemical Industry  相似文献   

Changes in distribution,morphology and ultrastructure of chloride cell in Atlantic salmon during an AGD infection     

Yao‐Chung Chang  Harry Hamlin‐Wright  Sean Monaghan  Tharangani Herath  Johanna Baily  Jorge del Pozo  Jamie Downes  Andrew Preston  Lynn Chalmers  Nilantha Jayasuriya  James E. Bron  Alexandra Adams  Sophie Fridman 《Journal of fish diseases》2019,42(10):1433-1446

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Conventional fractionated radiotherapy outcomes for young dogs with nephroblastoma of the spinal cord: 5 cases     

Jaeyoung Kim  Michael Sean Kent  Alain Pierre Théon  Amandine Tamara Lejeune  Katherine Sarah Hansen 《Veterinary and comparative oncology》2023,21(3):419-426

Published radiotherapy results for spinal nephroblastomas in dogs are limited. In this retrospective longitudinal study (1/2007–1/2022), five dogs with a median age of 2.8 years received post-operative 3D conformal, conventional fractionated radiotherapy (CFRT) with 2–4 fields (parallel-opposed with or without two hinge-angle fields), for an incompletely resected nephroblastoma. Clinical findings prior to surgery included one or more of the following: pelvic limb paresis (5), faecal incontinence (2), flaccid tail (1), non-ambulatory (2) and deep pain loss (1). All masses were located between T11 and L3 and surgically removed via hemilaminectomy. Dogs received 45–50 Gray (Gy) in 18–20 fractions, and no dogs received chemotherapy post-radiation. At analysis, all dogs were deceased, with none lost to follow-up. The median overall survival (OS) from first treatment to death of any cause was 3.4 years (1234 days; 95% CI 68 days-upper limit not reached; range: 68–3607 days). The median planning target volume was 51.3 cc, with a median PTV dose of 51.4 Gy and median D98 = 48.3 Gy. Late complications or recurrence was difficult to fully determine in this small dataset; however, some degree of ataxia persisted throughout life in all dogs. This study provides preliminary evidence that post-operative radiotherapy may result in prolonged survival times dogs with spinal nephroblastomas.  相似文献