共查询到20条相似文献,搜索用时 0 毫秒
1.
2.
Shingo Moriya Kanchu Tei Yutaka Yamazaki Hironobu Hata Yoshimasa Kitagawa Nobuo Inoue Hiroko Miura 《Gerodontology》2013,30(2):133-140
doi: 10.1111/j.1741‐2358.2012.00654.x Relationships between higher‐level functional capacity and dental health behaviors in community‐dwelling older adults Objective: The aim of the present study was to elucidate relationships between higher‐level functional capacity and dental health behaviours in community‐dwelling older adults. Background: In ageing society, it is necessary to promote oral health in the elderly, because good oral health is a significant contributing factor to good general health. Higher‐level functional capacity has been considered a crucial factor for successful independent living in the elderly. We hypothesised that functional capacity is a significant indicator of dental health behaviours. Methods: Three hundred and thirty‐eight adults aged 65 years or older were enrolled in this study. Higher‐level functional capacity was evaluated using the Tokyo Metropolitan Institute of Gerontology Index of Competence (TMIG‐index). Univariate and multivariate models were constructed with dental health behaviours, such as regular visits to a dentist, brushing frequency and use of extra cleaning devices, as the dependent variable, and the total TMIG‐index score and its subcategory scores as the principal independent variable. Results: Univariate logistic regression analysis demonstrated a significant correlation between low TMIG‐index and ‘intellectual activity’ subcategory scores to lack of regular visits to a dentist and not using extra cleaning devices. Using a multivariate model, significant relationships remained after adjusting for a number of variables including demographics, medical status, lifestyle and number of remaining teeth. Conclusion: Intellectual activity of higher‐level functional capacity may be an accurate indicator of dental health behaviours in community‐dwelling older adults. Intellectual activity should be taken into consideration to effectively promote oral health behaviours and oral hygiene in elderly persons living independently. 相似文献
3.
It has been commonly suggested that ants negatively affect plant pollination, particularly in the tropics. We studied ant–flower–pollinator
interactions in a lowland rainforest in Borneo. Frequency and duration of pollinator visits were compared between flowers
attended by ants and flowers from which ants were excluded. In all four plant species studied, the activity of ants decreased
the rate and/or duration of the pollinators’ floral visits. For this and other reasons it is expected that plants repel ants
from flowers during anthesis. We tested this prediction for a different set of plant species in which we observed the behaviour
of Dolichoderus thoracicus ants when encountering flowers. In eight out of 18 plant species studied, ants showed a significantly higher rejection rate
when they encountered flowers than when they encountered controls. Our results are thus consistent with the hypothesis that
ants may negatively affect plant fitness by reduced intensity of pollinator visits and that ants are repelled from flowers
of many tropical plant species, although this repellence is clearly not ubiquitous. 相似文献
4.
Keith D. Waddington 《Oecologia》1980,44(2):199-204
Summary Flight patterns of honeybees (Apis mellifera ligustica) were quantified as the bees foraged among artificial flowers for sugar solution (nectar). Bees exhibited considerable directionality on successive flights which minimized repeat visits to flowers and they usually made short flights to nearby flowers, thus minimizing flight time. The change in direction on successive flights between flowers were independent of the number of immediately preceding consecutive rewarding visits but decreased as the number of non-rewarding visits increased. Flight distances were short after visits to rewarding flowers but increased as the number of immediately preceding non-rewarding visits increased. The bees' rate of caloric intake (calories/time) was highest at the floral arrays having the highest density, and it was greater at arrays with clumped nectar-distributions than at those with randomly distributed nectar. These findings are explained in terms of the observed flight patterns.Contribution number 1660 from the Department of Entomology, University of Kansas, Lawrence, Kansas 66045, USA 相似文献
5.
Floral nectar characteristics of nine inbred lines of onion (Allium cepa L.) were examined to determine their influence on the attractiveness of the onion flowers to honey bees (Apis mellifera L.). Potassium concentrations and sugar concentrations of the nectar did not significantly correlate with the number of bee visits received by an umbel. The average amount of nectar produced by both the umbels and the individual florets was significantly positively correlated with the number of bee visits. Our results suggest that selection for flowers with high nectar production may lead to a higher rate of pollination of the onion seed crop. 相似文献
6.
Territorial male Thomson's and Grant's gazelles on a commercial game ranch near Nairobi, Kenya, were older, heavier and possessed longer horns than bachelor conspecifics. Among territorial Thomson's gazelles, males accompanied by females were older than solitary individuals but differed little in frame and horn dimensions. Small sample sizes precluded similar analyses for Grant's gazelles. These results suggest the importance of size, age and perhaps experience in determining social status. 相似文献
7.
Anna‐Maija H. Syrjälä Päivi I. Pussinen Kaija Komulainen Irma Nykänen Matti Knuuttila Piia Ruoppi Sirpa Hartikainen Raimo Sulkava Pekka Ylöstalo 《Gerodontology》2013,30(4):270-275
doi: 10.1111/j.1741‐2358.2012.00679.x Salivary flow rate and risk of malnutrition – a study among dentate, community‐dwelling older people Objective: To analyse the relation between unstimulated and stimulated salivary secretion and the risk of malnutrition among home‐dwelling elderly people. Background: Saliva has an important role in eating. Despite this, there are only a few studies on the role of salivary secretion in the development of malnutrition among elderly people. Materials and methods: The study population consisted of 157 subjects aged 75 or older. This was a part of GeMS study carried out in Kuopio, in eastern Finland. The data used in this study were collected by means of interviews and geriatric and oral clinical examinations. The risk of malnutrition was measured using the Mini Nutritional Assessment Short‐Form. Logistic regression models were used to estimate odds ratios (OR) and their 95% Confidence Intervals (CI). Results: Subjects with a low unstimulated salivary flow rate (<0.1 ml/min) or stimulated salivary flow rate (<1.0 ml/min) had no statistically significant increase in risk of malnutrition, OR: 1.3, CI: 0.5–3.9, OR: 1.5, CI: 0.5–4.2, respectively, when compared with those with a normal unstimulated and stimulated salivary flow rate. Conclusion: Our results do not support the concept that low salivary secretion is an important risk factor for malnutrition among community‐dwelling elders. 相似文献
8.
《Small Ruminant Research》2009,85(1-3):82-88
In the present study the relationships between five body structural and nine udder morphological traits with milk yield and non-yield traits, i.e. milk contents, somatic cell count and body weight in n = 171 Frizarta ewes were investigated. Positive correlations of moderate to high magnitude were observed among body measurements ranging from 0.25 (body length-chest width) to 0.61 (chest width-chest girth). High correlations were observed between udder width and udder circumference (r = 0.69) as well as between udder circumference at base and middle (r = 0.62). Udder height was found to be positively correlated with cistern depth (r = 0.32), udder width (r = 0.40) and udder circumference (r = 0.42) as well as with teat measurements (0.19 and 0.25 with teat length and teat circumference, respectively). Cistern depth was positively and highly correlated with teat angle (r = 0.64). The correlation between teat length and circumference was also high (r = 0.57). Teat angle was found to be negatively correlated with teat measurements (r = −0.39 and −0.23 for teat length and teat circumference, respectively). Principal components analysis revealed four components that jointly explained 67% of the variance of all the body and the udder morphological traits. The first principal component interpreted as the body dimensions was found to be associated with body weight of ewes. The second component interpreted as global and rear measurements of the udder was significant for milk yield traits. The third and fourth principal components were interpreted as the udder type and teat dimensions, respectively. Ewes’ body weight could be adequately predicted by chest girth, body length, chest width and withers height. Test day milk yields were found to be associated with udder circumference and udder width as well as with udder height and teat length. None of the udder measurements and/or teat characteristics was found to be correlated with milk content(s) and/or somatic cell count. New statistical techniques can be successfully implemented in investigation of relationships between various traits in dairy sheep. 相似文献
9.
Summary Milkweed (Asclepias syriaca L.) umbels and stems attended by ants (Lasius neoniger Emery and Tapinoma sessile (Say)) initiated significantly fewer pods and showed a trend to produce fewer mature pods than did umbels and stems not attended by ants. Since similar numbers of pollinia were inserted in ant-attended flowers, we hypothesize that ant-excluded flowers obtain more pollinia from other clones than do ant-attended flowers of this normally non-selfing species. If pollinators from other clones first visited flowers not depleted of nectar by ants, they could provide this source of foreign pollinia. Our experiments suggest that nocturnal noctuid and geometrid moths can provide these pollinia. 相似文献
10.
A. Gonzalez C. L. Rowe P. J. Weeks D. Whittle F. S. Gilbert C. J. Barnard 《Oecologia》1995,101(2):258-264
Bees foraging for nectar should choose different inflorescences from those foraging for both pollen and nectar, if inflorescences consist of differing proportions of male and female flowers, particularly if the sex phases of the flowers differ in nectar content as well as the occurrence of pollen. This study tested this prediction using worker honey bees (Apis mellifera L.) foraging on inflorescences of Lavandula stoechas. Female flowers contained about twice the volume of nectar of male flowers. As one would predict, bees foraging for nectar only chose inflorescences with disproportionately more female flowers: time spent on the inflorescence was correlated with the number of female flowers, but not with the number of male flowers. Inflorescence size was inversely correlated with the number of female flowers, and could be used as a morphological cue by these bees. Also as predicted, workers foraging for both pollen and nectar chose inflorescences with relatively greater numbers of both male and female flowers: time spent on these inflorescences was correlated with the number of male flowers, but not with the number of females flowers. A morphological cue inversely associated with such inflorescences is the size of the bract display. Choice of flowers within inflorescences was also influenced predictably, but preferences appeared to be based upon corolla size rather than directly on sex phase. 相似文献
11.
棉铃虫卵和龟纹瓢虫,中华草蛉分布格局的关系研究 总被引:5,自引:1,他引:5
通过田间调查,研究了棉铃虫卵和龟纹瓢虫、中华草蛉空间分布的关系.研究表明,棉铃虫卵和龟纹瓢虫、中华草蛉在棉株垂直各层上的数量间相关系数6 月分别为0 .5696 、0 .8620 ,7 月为0 .8300 、0 .9282 ,8 月为0 .9083 、0 .8201 ,除6 月龟纹瓢虫外,其余皆达显著或极显著水平;垂直格局上棉铃虫卵和龟纹瓢虫扩散系数和久野指数间相关系数分别为0 .8211 、0 .7791 ,皆达极显著水平;水平格局上棉铃虫卵和中华草蛉扩散系数和久野指数间相关系数分别为0 .7925 、0 .5228 ,分别达极显著和显著水平. 相似文献
12.
Animal-pollinated angiosperm plants that respond positively to nectar removal by replenishment invest energy that can entail a reproductive cost. We investigated whether or not nectar removal stimulates replenishment in two hummingbird-pollinated bromeliad species. Nectar replenishment rates were also assessed by removing nectar from manually pollinated flowers because pollination events might be used as signals to save energy by preventing allocation to post-pollination nectar production. Then we synthesized the current understanding of nectar removal effects by reviewing existing published studies with a meta-analysis. The magnitude and significance of estimated nectar removal effects and factors associated with variation in size and direction of nectar removal effects were elucidated with the meta-analysis. We found that both Tillandsia species strongly respond to repeated nectar removal by producing >3 times additional nectar. Nectar secretion patterns were not altered by pollination (stigmatic pollen deposition) and we found no evidence of nectar reabsorption. Although the effect size varied widely across systems and/or environmental conditions, the meta-analysis showed that nectar removal had overall a positive effect on nectar replenishment (mainly among species inhabiting wet tropical habitats such as Tillandsia), and a negative effect on the secretion of additional sugar, suggesting that those plants are resource limited and conservative in the secretion of additional sugar.Electronic Supplementary Material Supplementary material is available for this article at 相似文献
13.
14.
Moult is a costly but necessary process in avian life, which displays two main temporal patterns within the annual cycle of birds (summer and winter moult). Timing of moult can affect its duration and consequently the amount of material invested in feathers, which could have a considerable influence on feather structure and functionality. In this study, we used two complementary approaches to test whether moult duration and feather mass vary in relation to the timing of moult. Firstly, we conducted a comparative study between a sample of long‐distance migratory passerine species which differ in moult pattern. Secondly, we took advantage of the willow warbler's Phylloscopus trochilus biannual moult, for which it is well‐known that winter moult takes longer than summer moult, to assess between‐moult variation in feather mass. Our comparative analysis showed that summer moulting species performed significantly shorter moults than winter moulters. We also detected that feathers produced in winter were comparatively heavier than those produced in summer, both in between‐species comparison and between moults of the willow warbler. These results suggest the existence of a trade‐off between moult speed and feather mass mediated by timing of moult, which could contribute to explain the diversity of moult patterns in passerines. 相似文献
15.
Aim To quantify the regional‐scale spatio‐temporal relationships among rainfall, vegetation and fire frequency in the Australian wet–dry tropics (AWDT). Location Northern Australia: Cape York Peninsula, central Arnhem, central Kimberly, Einasleigh Uplands, Gulf Fall Uplands and northern Kimberley. Methods Monthly ‘fraction of photosynthetic active radiation absorbed by green vegetation’ (fAPAR) was decomposed into monthly evergreen (EG) and monthly raingreen (RG) components using time‐series techniques applied to monthly normalized difference vegetation index (NDVI) data from Advanced Very High Resolution Radiometer (AVHRR) imagery. Fire affected areas were independently mapped at the same spatio‐temporal resolution from AVHRR imagery. Weather station records were spatially interpolated to create monthly rainfall surfaces. Vegetation structural classes were derived from a digitized map of northern Australian vegetation communities (1 : 1,000,000). Generalized linear models were used to quantify relationships among the fAPAR, EG and RG signals, vegetation structure, rainfall and fire frequency, for the period November 1996–December 2001. Results The fAPAR and EG signals are positively correlated with annual rainfall and canopy cover, notably: EGclosed forest > EGopen heathland > EGopen forest > EGwoodland > EGopen woodland > EGlow woodland > EGlow open woodland > EGopen grassland. Vegetation height and fAPAR are positively correlated, excluding the special case of open heathland. The RG signal is highest where intermediate annual rainfall and strong seasonality in rainfall coincide, and is associated with vegetation structure as follows: RGopen grassland > RGwoodland > RGopen forest > RGopen heathland > RGlow woodland > RGopen woodland > RGlow open woodland > RGclosed forest. Monthly RG tracks monthly rainfall. Annual proportion of area burnt (PB) is maximal where high RG coincides with low EG (open grassland, several woodland communities). PB is minimal in vegetation where both RG and EG are low (low open woodland); and in vegetation where EG is high (closed forest, open heathland). Conclusions The RG–EG scheme successfully reflects digitally mapped tree and grass covers in relation to rainfall. RG–EG patterns are strongly associated with fire frequency patterns. PB is maximal in areas of high RG, where high biomass production during the wet season supports abundant fine fuel during the dry season. PB is minimal in areas with high EG, where relatively moist fuel limits fire ignition; and in areas with low EG and RG, where a relative short supply of fuel limits fire spread. 相似文献
16.
Slow bee paralysis virus (SBPV)—previously considered an obligate honeybee disease—is now known to be prevalent in bumblebee species. SBPV is highly virulent in honeybees in association with Varroa mites, but has been considered relatively benign otherwise. However, condition-dependent pathogens can appear asymptomatic under good, resource abundant conditions, and negative impacts on host fitness may only become apparent when under stressful or resource-limited conditions. We tested whether SBPV expresses condition-dependent virulence in its bumblebee host, Bombus terrestris, by orally inoculating bees with SBPV and recording longevity under satiated and starvation conditions. SBPV infection resulted in significant virulence under starvation conditions, with infected bees 1.6 times more likely to die at any given time point (a median of 2.3 h earlier than uninfected bees), whereas there was no effect under satiated conditions. This demonstrates clear condition-dependent virulence for SBPV in B. terrestris. Infections that appear asymptomatic in non-stressful laboratory assays may nevertheless have significant impacts under natural conditions in the wild. For multi-host pathogens such as SBPV, the use of sentinel host species in laboratory assays may further lead to the underestimation of pathogen impacts on other species in nature. In this case the impact of ‘honeybee viruses’ on wild pollinators may be underestimated, with detrimental effects on conservation and food security. Our results highlight the importance of multiple assays and multiple host species when testing for virulence, in order for laboratory studies to accurately inform conservation policy and mitigate disease impacts in wild pollinators. 相似文献
17.
Graham S. Begg Jane Wishart Mark W. Young Geoff R. Squire Pietro P. M. Iannetta 《Ecography》2012,35(5):446-457
Wild arable plants can be an economic burden but they also support diverse arable food webs and contribute to valuable ecosystem functions. These benefits may have been compromised over recent decades by declining weed diversity. The decline in wild arable plant diversity has been viewed predominantly in terms of species shifts a view that ignores the genetic and functional variation existing within species and the impact on ecological and evolutionary processes which this may have. To examine within‐species diversity, ISSR markers were used in parallel with environmental and phenotypic characterisation, to investigate the population structure and diversity of Capsella bursa‐pastoris (shepherd's purse) from arable fields in the UK. Analysis of 338 ISSR products for 109 individuals from 51 accessions obtained from the seed banks of 33 arable fields showed that in‐field populations of shepherd's purse were genetically differentiated between individuals, and among accessions and fields. In addition, cluster analysis identified three genetically distinct regional‐scale populations. Phenotypic variation was present at all scales of genetic differentiation, including the regional scale where populations differed in their key life‐history traits: flowering time, fecundity and dormancy. Genetic drift is proposed as a contributor to differentiation among genetically isolated but locally co‐occurring accessions. In addition, the genetic and phenotypic variation in shepherd's purse exhibited large scale, spatial trends and showed statistically significant associations with cropping intensity and soil‐pH. These results suggest that adaptation as a result of selection by cropping practise and soil‐pH has played a role in the ability of shepherd's purse to colonise and persist in arable fields. 相似文献
18.
19.
To observe temporal changes in the nectar volume of Impatiens flowers, we modified and used an interval‐shooting camera with a special flash system. Former methods of measuring nectar volume inevitably necessitated destruction or damage of the floral parts. As a consequence, accurate continuous measurements of nectar volume under natural conditions have been difficult. While considering how to overcome this problem we noticed that when flowers were observed against transmitted light from the sun, a silhouette of nectar was visible inside the spur. To exploit this phenomenon, we attached a polymer optical fiber to the built‐in flash of a compact digital camera and bent the fiber towards the camera's lens to provide backlighting. We took interval images and estimated the nectar volume from the size of nectar silhouette. To our knowledge, this is the first reported method involving the use of time‐interval photography for measuring nectar volume in situ. 相似文献
20.
Dino J. Martins 《African Journal of Ecology》2010,48(4):1115-1122
In obligate ant–plant mutualisms, the asymmetric engagement of a single plant species with multiple ant species provides the opportunity for partners to vary in their behaviour. Variation in behaviour has implications for the interactions with third‐party species such as herbivores. This study assessed the effect of obligate ant‐mutualists (Crematogaster mimosae, Crematogaster nigriceps and Tetraponera penzigi) inhabiting the African ant‐acacia (Acacia drepanolobium) on three mega‐herbivore browsers: the Maasai giraffe (Giraffa camelopardalis tippelskirchi), the reticulated giraffe (Giraffa c. reticulata) and the black rhino (Diceros bicornis). Giraffes are abundant and wide‐ranging herbivores of the acacias, whereas black rhinos are localized and perennial herbivores of the acacias. Multiyear field studies comparing the ants’ aggressive behaviour and browsing by mega‐herbivores suggested differences between the tending abilities of the primary ant species inhabiting A. drepanolobium. Trees occupied by the aggressive ant species C. mimosae had significantly less browsing by giraffes and black rhino than trees occupied by other ant species. The results of this study provide evidence that ant‐mutualists on African acacias can serve as deterrents to mega‐herbivores and that different ant species vary in their tending abilities. 相似文献