Impact of Native Grasses and Cheatgrass (Bromus tectorum) on Great Basin Forb Seedling Growth     

Hilary Parkinson  Cathy Zabinski  Nancy Shaw 《Strength and Conditioning Journal》2013,66(2):174-180

Re-establishing native communities that resist exotic weed invasion and provide diverse habitat for wildlife are high priorities for restoration in sagebrush ecosystems. Native forbs are an important component of healthy rangelands in this system, but they are rarely included in seedings. Understanding competitive interactions between forb and grass seedlings is required to devise seeding strategies that can enhance establishment of diverse native species assemblages in degraded sagebrush communities. We conducted a greenhouse experiment to examine seedling biomass and relative growth rate of common native forb species when grown alone or in the presence of a native bunchgrass or an exotic annual grass. Forb species included bigseed biscuitroot (Lomatium macrocarpum [Nutt. ex Torr. & A. Gray] J.M. Coult. & Rose), sulphur-flower buckwheat (Eriogonum umbellatum Torr.), hoary aster (Machaeranthera canescens [Pursh] Gray), royal penstemon (Penstemon speciosus Douglas ex Lindl.), and Munro's globemallow (Sphaeralcea munroana [Douglas ex Lindl.] Spach ex Gray); and neighboring grass species included bottlebrush squirreltail (Elymus elymoides [Raf.] Swezey), Sandberg bluegrass (Poa secunda J. Presl); and cheatgrass (Bromus tectorum L.). Forbs and grasses were harvested after 6, 9, or 12 wk of growth for biomass determination and calculation of relative growth rates (RGR) of forbs. Neither bunchgrass reduced biomass of any forb. RGR was reduced for royal penstemon when grown with either native grass and for Munro's globemallow when grown with bottlebrush squirreltail. Although only assessed qualitatively, forbs with vertically oriented root morphologies exhibited no reduction in RGR when grown with native grasses, compared to forbs with dense lateral branching, similar to the root morphology of native grasses. Biomass of forbs was reduced by 50% to 91% and RGR by 37% to 80% when grown with cheatgrass. Understanding native forb interactions with native grasses and cheatgrass will aid land managers in selecting effective seed mixes and making better use of costly seed.  相似文献   

Effect of trotting velocity on work patterns of the hind limbs of Greyhounds     

Colborne GR  Walker AM  Tattersall AJ  Fuller CJ 《American journal of veterinary research》2006,67(8):1293-1298

OBJECTIVE: To quantify the effects of trotting velocity on joint angular excursions, net joint moments, and powers across the hind limb joints in Greyhounds. ANIMALS: 5 healthy Greyhounds with no history of lameness of the hind limbs. PROCEDURES: Small reflective markers were applied to the skin over the joints of the hind limbs, and a 4-camera kinematic system was used to record positional data at 200 Hz in tandem with force platform data while the dogs trotted on a runway at slow, medium, and fast velocities. Breed-specific morphometric data were combined with kinematic and force data in an inverse-dynamics solution for net joint moments and powers at the hip, stifle, tarsal, and metatarsophalangeal joints. RESULTS: Angle, moment, and power patterns at the various joints were conserved among the 3 velocities. With increasing velocity, moments and powers at the tarsal, stifle, and hip joints during the stance phase were increased in amplitude, whereas amplitudes during the swing phase were not. The main contributors to increased velocity were the hip extensors and stifle flexors during the early part of the stance phase and the tarsal extensors during the late part of the stance phase. CONCLUSIONS AND CLINICAL RELEVANCE: Increases in trotting velocity in Greyhounds do not alter the basic patterns of work and power for various joints of the hind limbs, but local burst amplitudes during the stance phase increase incrementally.  相似文献   

Are the Traditional Medical Uses of Muricidae Molluscs Substantiated by Their Pharmacological Properties and Bioactive Compounds?     

Kirsten Benkendorff  David Rudd  Bijayalakshmi Devi Nongmaithem  Lei Liu  Fiona Young  Vicki Edwards  Cathy Avila  Catherine A. Abbott 《Marine drugs》2015,13(8):5237-5275

Marine molluscs from the family Muricidae hold great potential for development as a source of therapeutically useful compounds. Traditionally known for the production of the ancient dye Tyrian purple, these molluscs also form the basis of some rare traditional medicines that have been used for thousands of years. Whilst these traditional and alternative medicines have not been chemically analysed or tested for efficacy in controlled clinical trials, a significant amount of independent research has documented the biological activity of extracts and compounds from these snails. In particular, Muricidae produce a suite of brominated indoles with anti-inflammatory, anti-cancer and steroidogenic activity, as well as choline esters with muscle-relaxing and pain relieving properties. These compounds could explain some of the traditional uses in wound healing, stomach pain and menstrual problems. However, the principle source of bioactive compounds is from the hypobranchial gland, whilst the shell and operculum are the main source used in most traditional remedies. Thus further research is required to understand this discrepancy and to optimise a quality controlled natural medicine from Muricidae.  相似文献   

Changes in litter properties during decomposition: A study by differential thermogravimetry and scanning calorimetry     

Pere Rovira  Cathy Kurz-Besson  Marie-Madeleine Coûteaux  V. Ramón Vallejo 《Soil biology & biochemistry》2008,40(1):172-185

To verify the paradigm that organic matter (OM) quality (q) decreases with decomposition it is necessary to define q in strictly chemical, operational terms. We suggest defining q as the result of a balance between the energy stored in OM and the external supply of energy needed to release it. We apply this concept to the study of litter decomposition in four European pine forests: boreal, cool Atlantic, Mediterranean and warm Atlantic. Intact litter cores were taken and transported to the laboratory, where needles were sorted into six classes that summarize the main facts of the decomposition: melanisation, fragmentation and perforation by mesofauna. Each class was analyzed by both differential thermogravimetry and differential scanning calorimetry to obtain its spectra of weight loss and energy release.In the non-decomposed needles, two peaks of weight loss and energy release appear: a labile peak at about 350 °C, and a recalcitrant peak at about 450 °C. During decomposition, both peaks (but especially the recalcitrant one) move to lower temperatures, and their shapes change from well defined to flattened. In Mediterranean litters, a third peak appears at about 500 °C, due probably to refractory products of neoformation. There is a continuous increase in the energy stored in the remaining litter (in Joules per unit OM): this increase is concentrated in both the most thermolabile fractions (lost at temperatures <350 °C) and the most thermostable ones (>450 °C). With decomposition OM becomes more recalcitrant (i.e., it is lost at higher temperatures), but its stored energy becomes more available (i.e., it is released at lower temperatures). Overall, the energetic benefit/cost ratio increases. Thus, our results to date do not agree with the current paradigm that q decreases with decomposition; rather, they suggest that, at least in the first phases we studied, q is maintained or even increases.  相似文献   

Estimating stock depletion level from patterns of catch history          下载免费PDF全文

Shijie Zhou  André E Punt  Yimin Ye  Nick Ellis  Cathy M Dichmont  Malcolm Haddon  David C Smith  Anthony DM Smith 《Fish and Fisheries》2017,18(4):742-751

The degree to which a stock is depleted is one of the most important quantities in fisheries management because it is used to quantify the success of management and to inform management responses. However, stock depletion is extremely difficult to estimate, particularly with limited data. Using the RAM Legacy database, we developed a boosted regression tree (BRT) model to correlate depletion with a range of predictors calculated from catch data, making the model usable for many fisheries worldwide. The most important predictors were found to be catch trends obtained from linear regressions of scaled catch on time, including regression coefficients for the whole catch time series, the subseries before and after the maximum catch, and in recent years. Eight predictors explain about 80% of variation in depletion. There is a correlation of .5 between measured levels of depletion and the predictions of the BRT model. Predictions are less biased when the stock is fished down below half of the carrying capacity. The BRT model outperforms comparable existing catch‐based depletion estimators and could be used to provide priors for depletion for data‐poor stock assessment methods, or used more directly to provide estimates of the probability that depletion is below a given threshold value.  相似文献   

Spatio-temporal trends of longline fishing effort in the Southern Ocean and implications for seabird bycatch     

Geoffrey N Tuck  Tom Polacheck  Cathy M Bulman 《Biological conservation》2003,114(1):1-27

Longline fisheries have expanded throughout the world's oceans since major commercial distant-water pelagic fleets began fishing for tuna and tuna-like species in the early 1950s. Along with the more recent development and expansion of demersal longline fleets for species such as Patagonian toothfish, these vessels are a major source of mortality to several species of seabird. Vessels can set many thousands of baited hooks in a day across many kilometres of water. These waters are often used as foraging areas by wide-ranging seabirds. Attracted by baits and offal, the birds can be caught on the baited hooks and subsequently drown. To provide a greater understanding of the potential impact of the Southern Ocean's longline fleets on seabird populations, this paper describes the trends in longline effort of the major pelagic and demersal fisheries in southern waters. The total reported effort from all longline fleets south of 30°S has been well over 250 million hooks per year since the early 1990s. However the spatial and temporal distribution of this effort has not been constant. While effort from the Japanese pelagic distant-water longline fleet declined through the 1990s, the Taiwanese fleet expanded dramatically. Likewise demersal fishing for toothfish increased markedly during the mid-1990s. These fisheries, along with substantial illegal longline fisheries, may be placing the long-term viability of many Southern Ocean species of seabird in jeopardy.  相似文献   

Cooking decreases observed perfluorinated compound concentrations in fish   总被引：1，自引：0，他引：1  

Del Gobbo L  Tittlemier S  Diamond M  Pepper K  Tague B  Yeudall F  Vanderlinden L 《Journal of agricultural and food chemistry》2008,56(16):7551-7559

Dietary intake is a major route of exposure to perfluorinated compounds (PFCs). Although fish and seafood contribute significantly to total dietary exposure to these compounds, there is uncertainty with respect to the effect of cooking on PFC concentrations in these foods. Eighteen fish species purchased from markets in Toronto, Mississauga, and Ottawa, Canada were analyzed for perfluorooctanesulfonamide (PFOSAs)-based fluorochemicals and perfluorinated acids (PFAs) in raw and cooked (baked, boiled, fried) samples. Of 17 analytes, perfluorooctanesulfonic acid (PFOS) was detected most frequently; concentrations ranged from 0.21 to 1.68 ng/g ww in raw and cooked samples. PFOSAs were detected only in scallops at concentrations ranging from 0.20 ng/g ww to 0.76 ng/g ww. Total concentrations of PFAs in samples were 0.21 to 9.20 ng/g ww, respectively, consistent with previous studies. All cooking methods reduced PFA concentrations. Baking appeared to be the most effective cooking method; after baking samples for 15 min at 163 C (325 degrees F), PFAs were not detected in any of the samples. The margin of exposures (MOE) between the toxicological points of reference and the dietary intake of perfluorocarboxylates (PFCAs) and PFOS in fish and seafood muscle tissue were greater than 4 orders of magnitude. This indicates that reducing consumption of fish muscle tissue is not warranted on the basis of PFC exposure concerns at the reported levels of contamination, even for high fish consuming populations.  相似文献   

ULTRASOUND APPEARANCE OF AN EQUINE TESTICULAR SEMINOMA     

Cathy  Beck  BVSc  Jennifer A.  Charles  BVSc  Alistair A.  Maclean  BVSc 《Veterinary radiology & ultrasound》2001,42(4):355-357

A 16-year-old thoroughbred stallion developed sudden swelling of the left testicle. The stallion had previously been regarded as a unilateral cryptorchid. Ultrasound examination of the left testicle revealed a diffusely heterogeneous parenchyma. The testicle was diffusely hypoechoic with ill defined regions of hyperechogenicity giving the appearance of hypoechoic nodules throughout the testicular parenchyma. No normal testicular tissue was identifiable. An echogenic band, representing a pseudocapsule could be seen surrounding the testicle. Histopathologic diagnosis a seminoma.  相似文献   

MEASUREMENT OF AND CORRELATIONS BETWEEN FEVER, CHANGES IN THE PACKED CELL VOLUME AND PARASITAEMIA IN THE EVALUATION OF THE SUSCEPTIBILITY OF CATTLE TO INFECTION WITH BABESIA ARGENTINA   总被引：1，自引：0，他引：1  

L. L. Callow  B.V.Sc.  Ph.D. Patricia M.  Pepper M.Sc. 《Australian veterinary journal》1974,50(1):1-5

  相似文献   

Recommendations for Standards in Transthoracic Two-Dimensional Echocardiography in the Dog and Cat   总被引：14，自引：1，他引：13  

William P. Thomas DVM    Cathy E. Gaber DVM    Gilbert J. Jacobs DVM    Paul M. Kaplan DVM    Christophe W. Lombard  Dr.  Med Vet  N. Sydney Moise DVM  Bradley L. Moses DVM 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》1993,7(4):247-252

Recommendations are presented for standardized imaging planes and display conventions for two-dimensional echocardiography in the dog and cat. Three transducer locations ("windows") provide access to consistent imaging planes: the right parasternal location, the left caudal (apical) parasternal location, and the left cranial parasternal location. Recommendations for image display orientations are very similar to those for comparable human cardiac images, with the heart base or cranial aspect of the heart displayed to the examiner's right on the video display. From the right parasternal location, standard views include a long-axis four-chamber view and a long-axis left ventricular outflow view, and short-axis views at the levels of the left ventricular apex, papillary muscles, chordae tendineae, mitral valve, aortic valve, and pulmonary arteries. From the left caudal (apical) location, standard views include long-axis two-chamber and four-chamber views. From the left cranial parasternal location, standard views include a long-axis view of the left ventricular outflow tract and ascending aorta (with variations to image the right atrium and tricuspid valve, and the pulmonary valve and pulmonary artery), and a short-axis view of the aortic root encircled by the right heart. These images are presented by means of idealized line drawings. Adoption of these standards should facilitate consistent performance, recording, teaching, and communicating results of studies obtained by two-dimensional echocardiography. (Journal of Veterinary Internal Medicine 1993; 7:247–252. Copyright © 1993 by the American College of Veterinary Internal Medicine.)  相似文献