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Frequent Intervals (frequent + interval)
Selected AbstractsAn evidence-based approach to equine parasite control: It ain't the 60s anymoreEQUINE VETERINARY EDUCATION, Issue 6 2010R. M. Kaplan Summary Most veterinarians continue to recommend anthelmintic treatment programmes for horses that derive from knowledge and concepts more than 40 years old. However, much has changed since these recommendations were first introduced and current approaches routinely fail to provide optimal or even adequate levels of parasite control. There are many reasons for this. Recent studies demonstrate that anthelmintic resistance in equine parasites is highly prevalent and multiple-drug resistance is common in some countries, but few veterinarians take this into account when making treatment decisions or when recommending rotation of anthelmintics. Furthermore, the current approach of treating all horses at frequent intervals was designed specifically to control the highly pathogenic large strongyle, Strongylus vulgaris. But this parasite is now quite uncommon in managed horses in most of the world. Presently, the cyathostomins (small strongyles) are the principal parasitic pathogens of mature horses. The biology and pathogenesis of cyathostomins and S. vulgaris are very different and therefore require an entirely different approach. Furthermore, it is known that parasites are highly over-dispersed in hosts, such that a small percentage of hosts harbour most of the parasites. The common practices of recommending the same treatment programme for all horses despite great differences in parasite burdens, recommending prophylactic treatment of all horses without indication of parasitic disease or knowing what species of parasites are infecting the horses, recommending use of drugs without knowledge of their efficacy and failing to perform diagnostic (faecal egg count) surveillance for estimating parasite burdens and determining treatment efficacy, are all incompatible with current standards of veterinary practice. Consequently, it is necessary that attitudes and approaches to parasite control in horses undergo a complete overhaul. This is best achieved by following an evidence-based approach that takes into account all of these issues and is based on science, not tradition. [source] Prediction of crack opening stress levels for 1045 quenched and tempered steel under service loading spectraFATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 1 2006M. KHALIL ABSTRACT The opening stresses of a crack emanating from an edge notch in a 1045 quenched and tempered steel specimen were measured under two different Society of Automotive Engineers (SAE) standard service load histories having different average mean stress levels. The two spectra are the Grapple Skidder history (GSH), which has a positive average mean stress, and the Log Skidder history (LSH), which has a zero average mean stress. To capture the behaviour of the crack opening stress in the material, the crack opening stress levels were measured at 900X using an optical video microscope, at frequent intervals for each set of histories scaled to two different maximum stress ranges. A crack growth analysis based on a fracture mechanics approach was used to model the fatigue behaviour of the steel specimens for the given load spectra and stress ranges. Crack growth analysis was based on an effective strain-based intensity factor, a crack growth rate curve obtained during closure-free loading cycles and a local notch strain calculation based on Neuber's rule. The crack opening stress (Sop) was modelled and the model was implemented in a fatigue notch model, and the fatigue lives of the specimens under the two different spectra scaled to several maximum stress levels were estimated. The average measured crack opening stresses were between 6 and 12% of the average calculated crack opening stresses. In the interest of simplifying the use of Sop in design, the average Sop was correlated with the frequency of occurrence of the cycle reducing the Sop to the average crack opening stress level. The use of an Sop level corresponding to the cycle causing a reduction in Sop to a level reached once per 10 cycles gave a conservative estimate of average crack opening stress for all the histories. [source] Effects of feeding frequency on nestling begging and digestionIBIS, Issue 2 2008AMBER E. BUDDEN Nestling begging has the potential to provide parents with honest information about both short- and long-term nutritional needs, yet the importance of previous feeding experience remains largely untested in empirical studies. We examined the effect of two experimental feeding rates on nestling begging in Southern Grey Shrikes Lanius meridionalis using differences in load size to equalize the total volume of food received. There was variation in the pattern of begging behaviour between six pairs of siblings during a hand-feeding trial, although individuals maintained a similar begging intensity throughout a 9-h feeding period. Both treatment groups showed elevated begging responses during a terminal deprivation period, but nestlings fed small food items at frequent intervals demonstrated higher begging responses after a period of deprivation than did siblings fed large food items infrequently. As nestlings fed frequently with small food items had greater levels of undigested protein present in their faeces than birds fed large items infrequently, we suggest experimentally induced variation in digestive efficiency may account for the observed differences in begging behaviour. The possible role of learning, the adaptive significance of trade-offs between feeding rate and digestive efficiency, and a possible conflict of interests between parents and offspring are discussed. [source] An assessment of re-randomization methods in bark beetle (Scolytidae) trapping bioassaysAGRICULTURAL AND FOREST ENTOMOLOGY, Issue 4 2006Christopher J. Fettig Abstract 1,Numerous studies have explored the role of semiochemicals in the behaviour of bark beetles (Scolytidae). 2,Multiple-funnel traps are often used to elucidate these behavioural responses. Sufficient sample sizes are obtained by using large numbers of traps to which treatments are randomly assigned once, or by frequent collection of trap catches and subsequent re-randomization of treatments. 3,Recently, there has been some debate about the potential for trap contamination to occur when semiochemical treatments (baits), and not trap-treatment units (traps and baits), are re-randomized among existing traps. Due to the volatility of many semiochemicals, small levels of contamination could potentially confound results. 4,A literature survey was conducted to determine the frequency of re-randomizing semiochemical treatments (baits) vs. trap-treatment units (traps and baits) in scolytid trapping bioassays. An experiment was then conducted to determine whether differences in the response of Dendroctonus brevicomis LeConte to attractant-baited traps exist between the two methods. 5,The majority of papers examined reported use of a large number of fixed replicates (traps) rather than re-randomization of treatments at frequent intervals. Seventy-five percent of papers for which re-randomization methods could be determined reported relocation of semiochemical treatments (baits) only. 6,No significant differences in trap catch were observed among multiple-funnel traps aged with D. brevcomis baits (Phero Tech Inc., Canada) for 0, 30 and 90 days, suggesting that contamination did not influence the results. 7,It is concluded that re-randomizing baits is a viable cost-effective option to re-randomizing trap and bait units. [source] 160 Copepodology for the Phycologist with Apologies to G. E. HutchensonJOURNAL OF PHYCOLOGY, Issue 2003P. A. Tester Heterocapsa triquetra is one of the most common bloom forming dinoflagellates found in estuaries and near shore regions around the world. In order to bloom, H. triquetra optimizes a suite of factors including low grazing pressure, increased nutrient inputs, alternative nutrient sources, and favorable salinity and hydrodynamic conditions, as well as the negative factors of temperature-limited growth, short day lengths, and periods of transient light limitation. The prevailing environmental conditions associated its wintertime blooms are largely the result of atmospheric forcing. Low-pressure systems moved through coastal area at frequent intervals and are accompanied by low air temperatures and rainfall. Runoff following the rainfall events supplies nutrients critical for bloom initiation and development. Heterocapsa triquetra blooms can reach chl a levels >100 mg L,1 and cell densities between 1 to 6×106 L,1. As the blooms develop, nutrient inputs from the river became insufficient to meet growth demand and H. triquetra feeds mixotrophically, reducing competition from co-occurring phytoplankton. Cloud cover associated with the low-pressure systems light limit H. triquetra growth as do low temperatures. More importantly though, low temperatures limit micro and macrozooplankton populations to such an extent that grazing losses are minimal. [source] Adrenocortical and Pituitary Glucocorticoid Feedback in Abstinent Alcohol-Dependent WomenALCOHOLISM, Issue 5 2010Bryon Adinoff Background:, The long-term ingestion of alcohol diminishes hypothalamic,pituitary,adrenal (HPA) axis reactivity in alcohol-dependent men, potentially altering future relapse risk. Although sex differences in HPA axis functioning are apparent in healthy controls, disruptions in this system have received little attention in alcohol-dependent women. In this study, we assessed the basal secretory profile of adrenocorticotropic hormone (ACTH) and cortisol, adrenocortical sensitivity in both the presence and absence of endogenous corticotropic pituitary activation, and feedback pituitary glucocorticoid sensitivity to dexamethasone. Methods:, Seven women 4- to 8-week abstinent alcohol-only dependent subjects and 10 age-matched female healthy controls were studied. All subjects were between 30 and 50 years old, not taking oral contraceptives, and were studied during the early follicular phase of their menstrual cycle. Circulating concentrations of ACTH and cortisol were measured in blood samples collected at frequent intervals from 2000 to 0800 hour. A submaximal dose of cosyntropin (0.01 ,g/kg), a synthetic ACTH (1,24), was administered at 0800 hour to assess adrenocortical sensitivity. In a separate session, low-dose cosyntropin was also administered following high-dose dexamethasone (8 mg intravenous) to assess adrenocortical sensitivity in the relative absence of endogenous ACTH. In addition, the ACTH response to dexamethasone was measured to determine the pituitary glucocorticoid negative feedback. Sessions were 5 days apart, and blood draws were obtained every 5 to 10 minutes. Results:, Mean concentrations and pulsatile characteristics of ACTH and cortisol over 12 hours were not statistically different between the 2 groups. Healthy controls had a somewhat higher (p < 0.08) net peak, but not net integrated, cortisol response to cosyntropin relative to the alcohol-dependent women. There were no significant group differences in either the ACTH or cortisol response to dexamethasone nor in the net cortisol response to cosyntropin following dexamethasone. Conclusion:, Significant differences in pituitary,adrenal function were not apparent between alcohol-dependent women and matched controls. Despite the small n, it appears that alcohol-dependent women do not show the same disruptions in HPA activity as alcohol-dependent men. These findings may have relevance for gender-specific treatment effectiveness. [source] Continuous water-level monitoring in the assessment of groundwater remediation and refinement of a conceptual site modelREMEDIATION, Issue 4 2005John J. Quinn An Erratum has been published for this article in Remediation 16(1) 2005, 155,157. Water-level data collection is a fundamental component of groundwater investigations and remediation. While the locations and depths of monitored wells are important, the frequency of data collection may have a large impact on conclusions made about site hydrogeology. Data-logging water-level probes may be programmed to record water levels at frequent intervals, providing site decision makers with abundant, detailed information on the response of an aquifer to both anticipated and unforeseen stresses. In this study, a network of movable probes has provided several years of hourly water- level data. The understanding of the site's phytoremediation system has been enhanced by the continuous data, but subsequent insights into an unexpected situation regarding the site's infrastructure have been the most valuable result of the monitoring program. © 2005 Wiley Periodicals, Inc. [source] Coastal wetlands of the northern Gulf of California: inventory and conservation statusAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 1 2006Edward P. Glenn Abstract 1.Above 28°N, the coastline of the northern Gulf of California is indented at frequent intervals by negative or inverse estuaries that are saltier at their backs than at their mouths due to the lack of freshwater inflow. These ,esteros' total over 215 000 ha in area and encompass mangrove marshes below 29°N and saltgrass (Distichlis palmeri) marshes north of 29°N. An additional 6000 ha of freshwater and brackish wetlands are found in the Colorado River delta where fresh water enters the intertidal zone. 2.The mangrove marshes in the Gulf of California have been afforded some degree of protected status in Mexico, but the northern saltgrass esteros do not have priority conservation status and are increasingly becoming development targets for resorts, vacation homes and aquaculture sites. 3.We conducted an inventory of the marshes using aerial photography and satellite images, and evaluated the extent and type of development on each marsh. We reviewed the available literature on the marshes to document their vegetation types and ecological functions in the adjacent marine and terrestrial ecosystems. 4.Over 95% of the mangrove marshes have been developed for shrimp farming. However, the farms are built adjacent to, rather than in, the marshes, and the mangrove stands are still mostly intact. 5.The majority of saltgrass marshes above the mangrove line are still relatively unspoiled. However, resort and vacation home development is taking place on land surrounding them. 6.We recommend a system of protected reserves incorporating the pristine wetlands, along with water quality management and buffer zones for the more developed esteros. The saltgrass marshes should be considered for conservation protection, similar to the protection given to the southern mangrove marshes whose value has already been recognized. Copyright © 2006 John Wiley & Sons, Ltd. [source] Impact of Hyperthermal Rotary Blood Pump Surfaces on Blood Clotting Behavior: An ApproachARTIFICIAL ORGANS, Issue 9 2009Kathrin F. Hamilton Abstract The influence of heat dissipating systems, such as rotary blood pumps, was investigated. Titanium cylinders as rotary blood pump housing dummies were immersed in porcine blood and constantly tempered at specific temperatures (37,60°C) over a defined period of time. The porcine blood was anticoagulated either by low heparin dosage or citrate. At frequent intervals, samples were taken for blood analysis and the determination of the plasmatic coagulation cascade. Blood parameters do not alter at surface temperatures below 50°C. Hyperthermia-induced hemolysis could be confirmed. The plasmatic coagulation cascade is terminated at surface temperatures exceeding 55°C. The adhesion of blood constituents on surfaces is temperature and time dependent, and structural changes of adhesions and blood itself were detected. [source] Pharmacokinetics of enteric-coated mycophenolate sodium in stable liver transplant recipientsCLINICAL TRANSPLANTATION, Issue 3 2007Theodore W. Perry Abstract:, Introduction:, Mycophenolate mofetil (MMF) is one of the major immunosuppressive agents used in liver transplantation recipients. In an attempt to mitigate one of the most common side effects of MMF (gastrointestinal symptoms), enteric-coated mycophenolate sodium (EC-MPS) was developed. In this study, we report the pharmacokinetic profile of EC-MPS in stable liver transplantation recipients administered a single 720 mg dose. Methods:, Liver transplantation recipients more than one yr after transplantation were administered a single dose of 720 mg EC-MPS after which blood levels of MPA were measured at frequent intervals using a specific and validated LC-MS/MS assay. Results:, The characteristics of the 21 patients studied were: mean age was 55.9 yr, 13 were female, eight had hepatitis C, and 14 were on tacrolimus. The mean apparent half-life of MPA was 5.3 ± 4.3 h, (1.0,15.7). Mean tmax was 2.4 ± 1.1 h (1.0,5.0). The mean area-under-curve was 45.3 ± 23.1 ,g-h/mL (17.3,90.0). Trough level concentrations (C12 h) showed large inter-individual variability (0,9.2 ,g/mL). There was no difference in any of the pharmacokinetic parameters relative to: gender, HCV, administration of tacrolimus vs. cyclosporine or type of biliary anastomosis. Conclusions:, There is a wide variation in pharmacokinetic parameters in stable, long-term liver transplantation recipients receiving a single dose of EC-MPS. These data suggest that therapeutic drug monitoring with EC-MPS may have limited utility in liver transplantation recipients. [source] | ||||||||||||||||