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At least 109 records · Page 6Linked to original sources

PubMed2004

Alteration to lake trophic status as a means to control arsenic mobility in a mine-impacted lake.

The relationship between lake trophic status, sedimentary redox conditions and As mobility was examined in mine-impacted Balmer Lake, Canada. Under the current redox regime, the reductive dissolution of As-bearing Fe(III) oxyhydroxides occurs in close proximity to the sediment-water interface, resulting in the remobilization of dissolved As in the shallow porewaters to values as high as 8.5 mg L(-1). The shallow depth of the oxic zone limits the extent to which As can be re-sorbed in the interfacial horizons, and as a result, a proportion of the remobilized As escapes into the water column where it poses a water quality concern. Examination of the relationship between summer average chlorophyll a and total P at spring overturn in the lake water column demonstrates that Balmer Lake is currently eutrophic as a result of mining-derived inputs of P (domestic waters) and N (blasting residues and cyanide breakdown products). The results suggest that actively pushing the system towards oligotrophy by reducing non-natural P loadings to the system will decrease rates of in situ production and associated sediment oxygen demand, which will in turn result in increased thickness of the aerobic zone and enhanced As scavenging. Such conclusions are supported by porewater data which indicate that the flux of As to the water column is significantly reduced when the Fe(III) redox cline is situated at deeper sediment depths. In the absence of detailed P-loading data, it is recommended that P inputs be reduced to approximately 10% of the estimated pre-mining P loading of approximately 200 kg yr(-1). This implies reducing the collective P-loadings from the two mine sites adjacent to the lake from the approximate current value (approximately 150 kg yr(-1)) to approximately 20 kg yr(-1). It is proposed that establishment of oligotrophy in the lake should significantly mitigate the current level of dissolved As in lake waters.

Arsenic↗

PubMed1975

Decline of physiologic training effects during the competitive season in members of the U.S. Nordic ski team.

Various physiologic parameters were examined during submaximal and maximal treadmill exercise in nine members of the U.S. Nordic Ski Team prior to and following three months of on-snow ski training. In addition, four of this group were re-tested at the conclusion of the competitive skiing season. Results indicate a perceptible increase in training effect during the fall and early winter before starting on the European race circuit with subsequent decline in this effect as measured in the spring. It is suggested that this latter phenomenon occurs at least in part due to lack of adequate training time during the period of long-distance travel and racing.

Adaptation, Physiological↗

PubMed2005

Simulating the continuous curvilinear capsulorhexis procedure during cataract surgery on the EYESI system.

This paper describes a technique for simulating the capsulorhexis procedure during cataract surgery on the EYESI system. The continuous curvilinear capsulorhexis technique can be a difficult procedure for beginning ophthalmology surgeons. In the initial phase of tearing the tissue, the tear vector is tangential to the circumference of the tear circle. However, without the proper re-grasping of the flap of torn tissue close to the tear point, the tear vector angle quickly runs downhill possibly causing severe damage to the tissue. Novice surgeons tend to try to complete the capsulorhexis without the time consuming re-grasping of the tissue flap. Other factors such as anterior bowing of the lens diaphragm, patient age, and shallow anterior chambers add to the problematic nature of the procedure. The tissue area is modeled as a curvilinear mesh of nodes and springs. Deformation is accomplished via a physically based particle model utilizing a heuristic algorithm to constrain the deformation calculations to the locality of the tear area to speed up computations. The training software alerts the user of any potential tear problems before they occur thus instructing the novice surgeon. The EYESI hardware system (from VRMagic GmbH) provides the user with stereoscopic images thus providing 3D viewing. Our capsulorhexis simulator software models a number of tear problems and anomalies to provide a useful training environment without the dangers of using live patients.

Capsulorhexis↗

PubMed2004

Relationships among vernalization, shoot apex development and frost tolerance in wheat.

BACKGROUND AND AIMS: Frost tolerance of wheat depends primarily upon a strong vernalization requirement, delaying the transition to the reproductive phase. The aim of the present study was to learn how saturation of the vernalization requirement and apical development stage are related to frost tolerance in wheat. METHODS: 'Mironovskaya 808', a winter variety with a long vernalization requirement, and 'Leguan', a spring variety without a vernalization requirement, were acclimated at 2 degrees C at different stages of development. Plant development (morphological stage of the shoot apex), vernalization requirement (days to heading) and frost tolerance (survival of the plants exposed to freezing conditions) were evaluated. KEY RESULTS: 'Mironovskaya 808' increased its frost tolerance more rapidly; it reached a higher level of tolerance and after a longer duration of acclimation at 2 degrees C than was found in 'Leguan'. The frost tolerance of 'Mironovskaya 808' decreased and its ability to re-acclimate a high tolerance was lost after saturation of its vernalization requirement, but before its shoot apex had reached the double-ridge stage. The frost tolerance of 'Leguan' decreased after the plants had reached the floret initiation stage. CONCLUSIONS: The results support the hypothesis that genes for vernalization requirement act as a master switch regulating the duration of low temperature induced frost tolerance. In winter wheat, due to a longer vegetative phase, frost tolerance is maintained for a longer time and at a higher level than in spring wheat. After the saturation of vernalization requirement, winter wheat (as in spring wheat) established only a low level of frost tolerance.

Acclimatization↗

PubMed2002

Sub-clinical parasitism in spring-born, beef suckler calves: epidemiology and impact on growth performance during the first grazing season.

Sub-clinical parasitism in spring-born single suckled beef calves was investigated from the middle of their first grazing season until weaning or housing later the same year. The study was conducted on four beef suckler herds in southern England over a 3-year period and involved a total of 334 spring-born beef suckler calves and their dams. The animals were grazed extensively on pastures naturally infected with nematode larvae. At the start of each period of observation, faecal samples were taken from calves and cows and subjected to routine worm egg counts; calves were re-sampled at the end of the grazing season. In July in each year and at each location the calves were ranked by initial weight within sex, paired according to rank and randomly allocated to either an untreated control group or a group in which the calves were each treated with an ivermectin sustained-release (SR) bolus. The calves in both trial groups, and their dams, were grazed together until weaning or housing. The calves were weighed at the initial allocation and at the end of the study. The adult cows were not treated with any anthelmintic during the study. The faecal nematode egg counts (FECs) conducted in July showed that the suckler cows were excreting worm eggs at low concentrations: range 0-100 eggs per gram (epg), with one individual count of 500epg, 88% of the cows sampled had counts of <50epg. Similarly, the counts from the calf samples were fairly low in July: range 0-250epg, 73% of the calves sampled had counts of <50epg. By the end of the grazing season, the faecal samples from the untreated control calves showed higher values: range 0-650epg, with only 58% having an epg of <50. The average rate of daily liveweight gain in the untreated heifer calves was 0.79kg per day, the corresponding figure for the heifer calves treated with the ivermectin SR bolus in mid-summer was 0.88kg per day; the difference of 90g per day was significantly different (P=0.0118). The average rate of daily liveweight gain in the untreated bull calves was 0.91kg per day, the corresponding figure for the bull calves treated with the ivermectin SR bolus in mid-summer was 1.01kg per day; the difference was significantly different (P=0.0169).

Animals↗

PubMed1995

A study of the environmental survival of Mycobacterium bovis on a farm in New Zealand.

Mycobacterium bovis organisms absorbed on cotton ribbons were placed in different natural habitats on a farm in New Zealand. Mycobacterium bovis was not re-isolated from ribbons placed on pasture after 4 days. Survival on ribbons was longest in brushtail possum dens, where the maximum period of survival in dens was less than 7 days in summer and greater than 14 days but less than 28 days in winter and spring. The maximum period of survival on a forest floor was intermediate between pasture and dens less than 4 days in summer and greater than 14 days but less than 28 days in winter. The overall probability of survival was influenced by season and was shortest in summer and longest in spring and winter. Survival time increased as minimum daily temperatures decreased. These studies showed there was a relatively short period of survival of M. bovis outside hosts and support a conclusion that environmental contamination of pasture, particularly in summer months, may be relatively unimportant in the epidemiology of tuberculosis in cattle, deer and possums.

Journal Article↗

PubMed1999

Locoweed grazing.

Locoweed is the most widespread poisonous plant problem in the western U. S. Eleven species of Astragalus and Oxytropis (and many varieties within these species) cause locoism. Many locoweed species are endemic and are restricted to a narrow niche or habitat. Other locoweed species experience extreme population cycles; the population explodes in wet years and dies off in drought. A few species, such as O. sericea, are relatively stable and cause persistent poisoning problems. Knowledge of where locoweeds grow and the environmental conditions when they become a threat is important to manage livestock and avoid poisoning. Locoweeds are relatively palatable. Many locoweeds are the first plants to begin growth in the spring and regrow in the fall. Livestock generally prefer the green-growing locoweeds to other forage that is dormant in the late fall, winter, and spring. The most effective management strategy is to deny livestock access to locoweeds during critical periods when they are more palatable than the associated forage. Herbicides can control existing locoweed populations and provide "safe" pastures for critical periods. However, locoweed seed in soil will germinate and re-establish when environmental condition are favorable. Good range management and wise grazing strategies can provide adequate forage for livestock and prevent them from grazing locoweed during non-critical periods of the year when it is relatively less palatable than associated forages.

Animals↗

PubMed2003

Who owns Australia's water--elements of an effective regulatory model.

This paper identifies and describes a number of global trends in regulatory theory and legal scholarship. It points out the huge level of complexity demanded by globalisation and the unfortunate complication of this is that there is legal indeterminacy. The legal indeterminacy springs from the desire to amend and alter existing models. That has been the thrust of the Council of Australian Governments changes to adapt and add huge amounts of complexity to a flawed system. This paper argues that an effective water regulatory model requires a fundamental re-examination of the concept of water ownership and a capturing by the State of the right to allocate rainfall. This foundation is effective and the way forward to deal with the key issues in this transition phase. The second key element to an effective regulatory model is the concept of performance-based assessment. This requires information and schemes to be set up to work out ways to monitor and evaluate the performance of the utility on selected criteria. For Australia at present there is a dire lack of agreed criteria on these key issues and these have the potential to pull apart the whole process. The key issues are indigenous rights, governance issues, public participation, alteration of pre-existing rights and incorporation of environmental requirements.

Australia↗

PubMed2006

Effect of Neospora caninum-serostatus on culling, reproductive performance and milk production in Dutch dairy herds with and without a history of Neospora caninum-associated abortion epidemics.

We quantified the effect of Neospora caninum (NC)-serostatus on culling and (re)production in 83 herds randomly selected from the Dutch dairy herd population (random group) and in 17 herds that had experienced an abortion epidemic associated with NC infection (epidemic-abortion group). In the random group, a single whole-herd blood sampling was done during the spring of 2003, while in the epidemic-abortion group whole-herd blood sampling was done repeatedly at least once a year starting after the abortion epidemic during the period 1997-2000 until the summer of 2004. Serological test-results for NC were given as 'negative' (N), 'low-positive' (LP) and 'high-positive' (HP). For analysing the time to culling, calving interval and age of first calving, survival analysis was used. For categorical reproduction parameters either a logistic-regression model (abortion, non-return after 1st insemination) or a Poisson-regression model (number of inseminations per pregnancy) was used. For milk production a linear-mixed model was used. All models were controlled, if applicable, for confounding variables like parity, production, season, year and abortion and adjusted for within-herd clustering. In random herds, HP serostatus increased the hazard for culling 1.73-fold (95% CI: 1.37-2.19) compared to N and LP serostatus. Compared to N serostatus, LP and HP serostatus in epidemic-abortion herds increased the odds for abortion 1.88-fold (95% CI: 1.41-2.52) and 1.72-fold (95% CI: 1.38-2.14), respectively. No other reproduction parameters were associated with NC-serostatus in the random or epidemic-abortion herds. We found no effect of serostatus on milk production in the random group. In contrast, milk production of LP and HP serostatus in the epidemic-abortion group was respectively, 0.72kgmilk/day (95% CI: 0.15-1.03) and 0.59kgmilk/day (95% CI: 0.13-1.30), less during the first 100 days of lactation in the first year after the abortion epidemic compared with N serostatus.

Abortion, Veterinary↗

PubMed2005

The changing epidemiology of cryptosporidiosis in North West England.

Between 1996 and 2000, rates of cryptosporidiosis in North West England were significantly higher than overall in England and Wales, particularly during the first half of each year. In addition, during the second quarter of each year in this period, up to 40% of all cases recorded in England and Wales were from the North West Region. In 2001, cryptosporidiosis dramatically decreased throughout the United Kingdom and the springtime excess of cases formerly seen in the North West was no longer apparent. This changed epidemiology was due to a decline in cases of Cryptosporidium parvum (formerly genotype 2), associated with zoonotic transmission. Although the initial loss of a spring peak of infection corresponded with the outbreak of foot-and-mouth disease throughout the United Kingdom, its continued absence relates to major structural changes in the North West public water supply. This study highlights the far-reaching public health benefit of local working relationships in addressing re-occurring disease issues.

Adolescent↗

PubMedDate not supplied

Traumatic lesions of the metatarsophalangeal joint of the great toe in athletes.

In the 1972, 1973, and 1974 football seasons at the University of Arkansas, 74 players sustained sprains of the ankle, producing a total of 152 missed practices and 6 missed games. Although only 18 injuries of the first metatarsophalangeal joint complex were seen, these later resulted in 92 missed practices and 7 missed games. This injury has been a significant problem for both the university and for most other major institutions, judging from a 70% response to 94 questionnaires sent to trainers of 94 large colleges and universities throughout the United States. It is the researchers opinion that the artificial turf surface, particularly as it ages, the shoes, and shoe fitting are all possible contributors to the incidence of the problem. Nonoperative treatment, whose hallmark is rest, is the treatment of first choice. Taping and splinting with a 0.51-mm spring steel splint with reinforcement, both pre- and postinjury, are beneficial. Injections of steroids or any other attempt to return the still painful athlete to activity are contraindicated. Late surgery, particularly in the event of capsular ruptures, as well as early repair, can be of benefit. The need to re-evaluate the shoes and playing surfaces in the light of this and other injuries is emphasized.

Athletic Injuries↗

PubMed1987

Changes in plasma concentrations of LH, FSH and prolactin in ewes receiving melatonin and short-photoperiod treatments to induce early onset of breeding activity.

Breeding activity was similarly advanced in ewes given continuous (s.c. implant) or timed (oral dose at 15.30 h) melatonin treatments or subjected to a short (8 h light: 16 h darkness) artificial photoperiod. Treatments commenced in mid-June and were terminated in mid-November. Weekly and serial blood samples were collected before and after treatments commenced, to ascertain the effects on plasma prolactin, LH and FSH concentrations. In addition, serial blood samples were collected for 24 h plasma prolactin and melatonin estimations before and after cessation of the treatments. Plasma prolactin levels were significantly reduced immediately following the start of the melatonin (implant and oral) and short-photoperiod treatments but 'rebounded' to levels greater than control values. The normal seasonal (spring) rise in plasma prolactin was noted in the following year. Before the onset of breeding activity, mean plasma LH and FSH concentrations and LH pulse frequency did not change following any of the treatments. The 24-h plasma melatonin profile accurately reflected the various applied treatments but had re-entrained to the prevailing (natural) photoperiod 1 week after termination of the treatments. There were no significant group differences in 24-h plasma prolactin levels 1 week before or 1 and 11 weeks after the treatments had ceased. Such treatments, although successfully advancing the onset of breeding activity and modifying the seasonal plasma prolactin rhythm, were not manifested through any apparent change in peripheral LH or FSH.

Animals↗

PubMed2006

Means used for terrestrial rabies elimination in France and policy for rabies surveillance in case of re-emergence.

In France, the first case of wildlife rabies was detected in 1968, with the red fox (Vulpes vulpes) as reservoir and vector of terrestrial rabies. The last case was reported at the end of 1998. The maximum infected area amounted to 140,000 km2 in 1989 with a record number of 4,213 infected wild and domestic animals. The contaminated areas included various landscapes such as low populated farming areas and low mountainous areas as well as very densely populated areas and industrial areas contiguously urbanised. Oral vaccination of wildlife against rabies was implemented in 1986 and 1987 on limited areas treated by hand distribution and then helicopter distribution was implemented in 1988. The control of wildlife rabies was centralised at the country level in one institute for elaboration of baiting strategies, rabies surveillance network, laboratory investigations such as tetracycline and serological testing, vaccine titration and rabies diagnosis. Oral vaccination campaigns were organised in spring and in autumn by dropping annually 40 baits/km2. The following vaccine baits were used: SAD B19 from 1986 to 1992, SAG1/SAG2 from 1990 to 2003 and VRG from 1989 to 2003. A cost analysis study of the system of oral vaccination implemented in France demonstrated that it is beneficial compared to the traditional expenses of rabies control. Animal rabies prophylaxis has been progressively adapted to the disease free status of the country; the surveillance network for rabies is still working and an emergency procedure is in place in the event of a re-emergence of the disease in the context of high density fox populations.

Administration, Oral↗

PubMed2003

Seasonal variation in relapse rate of graves' disease after thionamide drug treatment.

OBJECTIVE: Controversy abounds on the issue of seasonal variation in new onset of Graves' disease, partly due to the difficulty of precisely dating the exact start of symptoms. To address the possible relationship between climatic changes and disease activity from a different perspective, we reviewed time of relapse during regular follow-up after successful drug treatment with thionamides. DESIGN: Retrospective analysis of a case series in a university clinic. PATIENTS AND MEASUREMENTS: We consecutively registered patients who experienced re-emergence of hyperthyroidism between 1992 and 2001 after successful antithyroid drug therapy. Excluded were subjects with superimposing painless thyroiditis, in postpartum, on immunomodulatory drugs, or off thionamides prematurely on their own volition. RESULTS: Fifty-two patients recurred 2 to 36 months after drug cessation. The frequency was higher in spring and summer (March to August) than in autumn and winter (September to February). With a new coated-tube radioreceptor assay, TSH binding inhibitor immunoglobulin activity was detected in sera from 87.5% of the reworsened patients. CONCLUSIONS: Graves' disease tends to relapse more frequently in spring and summer. Further clinical studies are warranted to clarify underlying mechanism (s) for this seasonal variation.

Adult↗

PubMed2006

Seasonal variations in active dispersal of natural populations of Triatoma infestans in rural north-western Argentina.

The flight dispersal of Triatoma infestans Klug (Hemiptera: Reduviidae) is one of the main mechanisms determining community re-infestation after control interventions. An empirical model of flight initiation coupled with data from a longitudinal study predicted that the flight dispersal of T. infestans would peak in summer. To test this prediction, longitudinal light trap collections were conducted during 3-8 nights in March (late summer), July (winter) and November (spring) 2003, and in March 2004 in a rural community in north-west Argentina. Following each light-trapping collection date, all peridomestic sites around light traps were inspected to assess the relative abundance and nutritional status of T. infestans at each site. A total of 21 adult and five nymph T. infestans, six Triatoma guasayana Wygodzinsky & Abalos, and nine Triatoma garciabesi Carcavallo et al. were collected in 96 light-trapping nights, whereas 696 T. infestans were collected from the peridomestic sites that surrounded the light traps. The arrival of T. infestans in the light traps occurred in 64% of catch stations and peaked in the summer surveys (10-14 bugs) compared with spring and winter surveys. When winds were < 5 km/h, the arrival of adult T. infestans at the light traps was significantly associated with maximum temperature and relative humidity. This is the first field report of seasonal variations in the flight dispersal activity of T. infestans.

Animal Migration↗

PubMed2006

Knowledge loss of medical students on first year basic science courses at the University of Saskatchewan.

BACKGROUND: Many senior undergraduate students from the University of Saskatchewan indicated informally that they did not remember much from their first year courses and wondered why we were teaching content that did not seem relevant to later clinical work or studies. To determine the extent of the problem a course evaluation study that measured the knowledge loss of medical students on selected first year courses was conducted. This study replicates previous memory decrement studies with three first year medicine basic science courses, something that was not found in the literature. It was expected that some courses would show more and some courses would show less knowledge loss. METHODS: In the spring of 2004 over 20 students were recruited to retake questions from three first year courses: Immunology, physiology, and neuroanatomy. Student scores on the selected questions at the time of the final examination in May 2003 (the 'test') were compared with their scores on the questions 10 or 11 months later (the 're-test') using paired samples t -tests. A repeated-measures MANOVA was used to compare the test and re-test scores among the three courses. The re-test scores were matched with the overall student ratings of the courses and the student scores on the May 2003 examinations. RESULTS: A statistically significant main effect of knowledge loss (F = 297.385; p < .001) and an interaction effect by course (F = 46.081; p < .001) were found. The students' scores in the Immunology course dropped 13.1%, 46.5% in Neuroanatomy, and 16.1% in physiology. Bonferroni post hoc comparisons showed a significant difference between Neuroanatomy and Physiology (mean difference of 10.7, p = .004). CONCLUSION: There was considerable knowledge loss among medical students in the three basic science courses tested and this loss was not uniform across courses. Knowledge loss does not seem to be related to the marks on the final examination or the assessment of course quality by the students.

Adult↗

PubMed1977

["Chronic inguinal strain" in top-athletes and its treatment (author's transl)].

The picture of "chronic inguinal strain" must be regarded as a further development of the "gracilis-syndrome" described by Schneider in 1964 (posttraumatic pibic osteonecrosis). These are rupture of the tendons of gracilis and adductor-longus, degenerated at their points of insertion on the pubic bone. Only surgery is successful. As described by Schneider, the tendon is divided and osteonecrotic tissue removed. If there is rupture the necrotic part of the tendon is excised, the remainder suture red to the nearby tendon. Re-fixation of the tendon at the pubic bone is unnecessary because of the very monor adduction-function of gracilis. Return to sport will be possible-on average-after 6-8 weeks.

Adult↗

PubMed2000

Retention of social recognition after hibernation in Belding's ground squirrels.

The retention of social memory during long periods of separation, such as hibernation or migration, has not been well documented, despite evidence for long-term social relationships in migrating species or in long-lived sedentary species. We investigated the ability of captive Belding's ground squirrels, Spermophilus beldingi, to remember previously familiar individuals as well as littermates after 9 months of isolation. Before hibernation, young ground squirrels discriminated between odours of familiar and unfamiliar individuals, as shown by greater investigation of a novel individual's odour. The following spring, these yearlings did not respond differentially to odours of previously familiar and unfamiliar individuals, suggesting that memory for familiar conspecifics was lost during hibernation. In contrast, both female and male yearlings continued to discriminate between odours of littermates and previously familiar nonlittermates. Thus, recognition of close kin was maintained during prolonged social isolation, but recognition of familiar, unrelated individuals was not. If re-establishment of familiarity is not costly or if adults rarely interact with the same individuals in successive years, then selection may not favour retention of individual memories of particular conspecifics over the winter. Even though males rarely encounter kin after dispersal, yearling males did recognize their siblings, suggesting that the relative costs of maintaining kin-recognition abilities year-round may be low. Possible mechanisms underlying the formation and maintenance of individual and kin recognition are discussed. Copyright 2000 The Association for the Study of Animal Behaviour.

Journal Article↗