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1.
Public acceptance of evolution in Northeastern U.S. is the highest nationwide, only 59%. Here, we compare perspectives about evolution, creationism, intelligent design (ID), and religiosity between highly educated New England faculty (n = 244; 90% Ph.D. holders in 40 disciplines at 35 colleges/universities) and college students from public secular (n = 161), private secular (n = 298), and religious (n = 185) institutions: 94/3% of the faculty vs. 64/14% of the students admitted to accepting evolution openly and/or privately, and 82/18% of the faculty vs. 58/42% of the students thought that evolution is definitely true or probably true, respectively. Only 3% of the faculty vs. 23% of the students thought that evolution and creationism are in harmony. Although 92% of faculty and students thought that evolution relies on common ancestry, one in every four faculty and one in every three students did not know that humans are apes; 15% of the faculty vs. 34% of the students believed, incorrectly, that the origin of the human mind cannot be explained by evolution, and 30% of the faculty vs. 72% of the students was Lamarckian (believed in inheritance of acquired traits). Notably, 91% of the faculty was very concerned (64%) or somehow concerned (27%) about the controversy evolution vs creationism vs ID and its implications for science education: 96% of the faculty vs. 72% of the students supported the exclusive teaching of evolution while 4% of the faculty vs. 28% of the students favored equal time to evolution, creationism and ID; 92% of the faculty vs. 52% of the students perceived ID as not scientific and proposed to counter evolution or as doctrine consistent with creationism. Although ≈30% of both faculty and students considered religion to be very important in their lives, and ≈20% admitted to praying daily, the faculty was less religious (Religiosity Index faculty = 0.5 and students = 0.75) and, as expected, more knowledgeable about science (Science Index faculty = 2.27 and students = 1.60) and evolution (Evolution Index faculty = 2.48 and students = 1.65) than the students. Because attitudes toward evolution correlate (1) positively with understanding of science/evolution and (2) negatively with religiosity/political ideology, we conclude that science education combined with vigorous public debate should suffice to increase acceptance of naturalistic rationalism and decrease the negative impact of creationism and ID on society’s evolution literacy.  相似文献   

2.
Acceptance of evolution by educators of prospective teachers remains superficially studied despite their role in having mentored schoolteachers whose weak support of evolution is known. Here, we contrast the views of New England educators of prospective teachers (n = 62; 87% Ph.D./doctorate holders in 32 specializations) with those of the general faculty (n = 244; 93% Ph.D./doctorate holders in 40 disciplines), both members of 35 colleges and universities, and with college students (n = 827; subsample of the 35 institutions) who were polled on: (1) the controversy evolution vs. creationism vs. intelligent design (ID), (2) their understanding of how science/evolution works, and (3) their religiosity. The educators held intermediate positions in respect to the general faculty and the students: 94% of the general faculty, 75% of the educators, and 63% of the students said they accepted evolution openly; and 82% of the general faculty, 71% of the educators, and 58% of the students thought that evolution is definitely true. Only 3% of the general faculty in comparison to 19% of the educators and 24% of the students thought that evolution and creationism are in harmony. Although 93% of the general faculty, educators, and students knew that evolution relies on common ancestry, 26% of the general faculty, 45% of the educators, and 35% of the students did not know that humans are apes. Remarkably, 15% of the general faculty, 32% of the educators, and 35% of the students believed, incorrectly, that the origin of the human mind cannot be explained by evolution; and 30% of the general faculty, 59% of the educators, and 75% of the students were Lamarckian (=believed in inheritance of acquired traits). For science education: 96% of the general faculty, 86% of the educators, and 71% of the students supported the exclusive teaching of evolution, while 4% of the general faculty, 14% of the educators, and 29% of the students favored equal time to evolution, creationism and ID; note that 92% of the general faculty, 82% of the educators, and 50% of the students perceived ID as either not scientific and proposed to counter evolution based on false claims or as religious doctrine consistent with creationism. The general faculty was the most knowledgeable about science/evolution and the least religious (science index, SI = 2.49; evolution index, EI = 2.49; and religiosity index, RI = 0.49); the educators reached lower science/evolution but higher religiosity indexes than the general faculty (SI = 1.96, EI = 1.96, and RI = 0.83); and the students were the least knowledgeable about science/evolution and the most religious (SI = 1.80, EI = 1.60, and RI = 0.89). Understanding of science and evolution were inversely correlated with level of religiosity, and understanding of evolution increased with increasing science literacy. Interestingly, ≈36% of the general faculty, educators and students considered religion to be very important in their lives, and 17% of the general faculty, 34% of the educators, and 28% of the students said they prayed daily. Assessing the perception of evolution by educators of prospective teachers vs. the general faculty and the students of New England, one of the historically most progressive regions in the U.S., is crucial for determining the magnitude of the impact of creationism and ID on attitudes toward science, reason, and education in science.  相似文献   

3.
Molecular genetic assays can contribute to conservation of aquatic taxa by assessing evolutionary and taxonomic distinctiveness, levels of genetic variation within and between populations, and the degree of introgression with introduced taxa. The Athabasca River drainage of␣western Alberta, Canada is one of only three (and the largest) drainages flowing east of the continental divide that contain native populations of rainbow trout (Salmonidae: Oncorhynchus mykiss). The “Athabasca” rainbow trout has been considered a preglacial relict worthy of special conservation measures. In addition, the native range of Athabasca rainbow trout has seen many instances of introductions of non-native populations since the beginning of the 20th century. We assayed rainbow trout from the Athabasca River drainage, from hatchery populations, and from representative populations in adjacent regions (N = 49 localities) for variation at 10 microsatelite loci to assess the level of evolutionary distinctiveness of Athabasca rainbow trout, and to assess the levels of introgression with non-native hatchery fish. We found that native Athabasca rainbow trout did not form a distinctive genetic assemblage and that the greatest amount of allele frequency variation was attributable to contemporary drainage systems (29.3%) rather than by a Athabasca/non-Athabasca distinction (12.6%). We found that 78% of all fish were confidently assigned to a “wild” rather than a “hatchery” genetic grouping and that most of the inferred introgression with hatchery fish was restricted to a few localities (N = 6). Our results suggest that: (i)␣Athabasca River rainbow trout are likely postglacial immigrants from adjacent populations of the Fraser River, and (ii) that there is no evidence of widespread introgression of hatchery alleles into native Athabasca River drainage rainbow trout.  相似文献   

4.
In this study, we investigated what problems urban marmosets (Callithrix penicillata) face in a city environment through the analysis of responses to callouts (N = 348) made by the environmental police of Belo Horizonte, Minas Gerais, Brazil, in the period from 2002 to 2007. Our objective was to characterise the problems faced by the marmosets and human city dwellers. The environmental police responded to two types of callouts: (1) solicitation whereby a person called them to report a problem (N = 218); and (2) the report of a hurt or injured animal (N = 127). On average, one callout per week was made in relation to urban marmosets. We found no time of year effects in relation to callouts, or any effect of gender or age of the person making the callout (P > 0.05). Furthermore, we found no environmental (e.g. percentage of “green area”) or socioeconomical variables (e.g. salary levels) of the city’s administrative regions associated with callouts (P > 0.05). The majority of callouts resulted in the attempt to capture marmosets (N = 345), and usually, only one animal was captured (N = 309). Many of these animals were released into city forest fragments (N = 146). Some sick animals were sent to veterinary clinics (N = 25) whereas others or confiscated animals were sent to the government’s wildlife processing centre (N = 143). From this data, we were able to make a series of recommendation about how the management of urban marmosets could be improved.  相似文献   

5.
Members of the epidermal growth factor receptor (EGFR) family of proteins are frequently overactive in solid tumors. A relatively new therapeutic approach to inhibit the kinase activity is the use of ATP-competitive small molecules. In silico techniques were employed to identify the key interactions between inhibitors and their protein receptors. A series of EGFR inhibitory anilinoquinolines was studied within the framework of hologram quantitative structure activity relationship (HQSAR), density functional theory (DFT)-based QSAR, and three-dimensional (3D) QSAR (CoMFA/CoMSIA). The HQSAR analysis implied that substitutions at certain sites on the inhibitors play an important role in EGFR inhibition. DFT-based QSAR results suggested that steric and electronic interactions contributed significantly to the activity. Ligand-based 3D-QSAR and receptor-guided 3D-QSAR analyses such as CoMFA and CoMSIA techniques were carried out, and the results corroborated the previous two approaches. The 3D QSAR models indicated that steric and hydrophobic interactions are dominant, and that substitution patterns are an important factor in determining activity. Molecular docking was helpful in identifying a bioactive conformer as well as a plausible binding mode. The docked geometry-based CoMFA model with steric and electrostatic fields effect gave q 2 = 0.66, r 2 = = 0.94 with r 2 predictive = 0.72. Similarly, CoMSIA with hydrophobic field gave q 2 = 0.59, r 2 = 0.85 with r 2 predictive = 0.63. Bulky groups around site 3 of ring “C”, and hydrophilic and bulky groups at position 6 of ring “A” are desirable, with a hydrophobic and electron-donating group at site 7 of ring “A” being helpful. Accordingly, potential EGFR inhibitors may be designed by modification of known inhibitors.  相似文献   

6.
There are major variations in the susceptibility to weight gain among individuals under similar external influences (decreased physical activity and excessive calorie intake), depending on the genetic background. In the present study, we performed a microarray analysis and real-time PCR validations in order to find out differential gene expression in subcutaneous abdominal adipose tissue from two groups of subjects that despite living in similar environmental conditions such as a habitual high-fat dietary intake (energy as fat >40%) and similar moderate physical activity, some of them were successfully “resistant” (lean) to weight gain, while others were “susceptible” to fat deposition (obese). The classification of up- and downregulated genes into different categories, together with the analysis of the altered biochemical pathways, revealed a coordinated downregulation of catabolic pathways operating in the mitochondria: fatty acid β oxidation (P = 0.008), tricarboxylic acid cycle (P = 0.001), and electron transport chain (P = 0.012). At the same time, glucose metabolism (P = 0.010) and fatty acid biosynthesis (P = 0.011) pathways were also downregulated in obese compared to lean subjects. In conclusion, our data showed an orchestrated downregulation of nuclear-encoded mitochondrial gene expression. These genes are involved in cellular respiration and oxidative metabolic pathways and could play a role in the susceptibility to weight gain in some individuals.  相似文献   

7.
Based on the U.S. Federal Mortality Schedules from the years 1850–1880 infant deaths <1 year were investigated in order to determine whether mortality attributed to “smothering” or “overlaying” followed known SIDS trajectories. By comparing a case sample of 2,236 smothered/overlaid deaths with an age-, regionally and time-matched control sample of all-cause infant deaths (N = 58,293), striking similarities with SIDS became apparent, which were not mimicked in the control sample. These epidemiological traits included a disproportionate vulnerability during the second to fourth month of life (Poisson RR 12.94, p < 0.001), a remarkable birth and death seasonality, as well as pronounced racial disparities. The study could also corroborate sex-specific discrepancies—such as differential impact of month of birth on age-at-death. Results of a Cox regression furthermore indicate that age, sex, race and death season were significant predictors of mortality. This strongly supports the hypothesis that these infant deaths represent empirical evidence of 19th century SIDS.  相似文献   

8.
Nitrogen controls on fine root substrate quality (that is, nitrogen and carbon-fraction concentrations) were assessed using nitrogen availability gradients in the Harvard Forest chronic nitrogen addition plots, University of Wisconsin Arboretum, Blackhawk Island, Wisconsin, and New England spruce-fir transect. The 27 study sites encompassed within these four areas collectively represented a wide range of nitrogen availability (both quantity and form), soil types, species composition, aboveground net primary production, and climatic regimes. Changes in fine root substrate quality among sites were most frequently and strongly correlated with nitrate availability. For the combined data set, fine root nitrogen concentration increased (adjusted R 2 = 0.46, P < 0.0001) with increasing site nitrate availability. Fine root “extractive” carbon-fraction concentrations decreased (adjusted R 2 = 0.32, P < 0.0002), “acid-soluble” compounds increased (adjusted R 2 = 0.35, P < 0.0001), and the “acid-insoluble” carbon fraction remained relatively high and stable (combined mean of 48.7 ± 3.1% for all sites) with increasing nitrate availability. Consequently, the ratio of acid-insoluble C–total N decreased (adjusted R 2 = 0.40, P < 0.0001) along gradients of increasing nitrate availability. The coefficients of determination for significant linear regressions between site nitrate availability and fine root nitrogen and carbon-fraction concentrations were generally higher for sites within each of the four study areas. Within individual study sites, tissue substrate quality varied between roots in different soil horizons and between roots of different size classes. However, the temporal variation of fine root substrate quality indices within specific horizons was relatively low. The results of this study indicate that fine root substrate quality increases with increasing nitrogen availability and thus supports the substrate quality component of a hypothesized conceptual model of nitrogen controls on fine root dynamics that maintains that fine root production, mortality, substrate quality, and decomposition increase with nitrogen availability in forest ecosystems in a manner that is analogous to foliage.  相似文献   

9.
A new species Dolichopteryx minuscula is described on the basis of three specimens [49.4–59.6 mm in standard length (SL)] collected from the Indo-West Pacific. The new species is characterized by pouchlike eyes with a small lens (lens diameter 2.2% SL), an adipose fin, the anal fin base originating posterior to the dorsal fin base, and 16–17 (= 5–6 + 1 + 10–11) gill rakers. Total fecundity was relatively low, only 658 ova being obtained from one specimen, despite the ovary being mature. Ovarian eggs were clearly subdivided into “undeveloped” (0.1–0.7 mm diameter classes, n = 561) and “developed” (1.0–1.3 mm classes, n = 97) groups, based on their frequency distribution. Such relatively low fecundity and frequency distributions of ovarian eggs suggest that Dolichopteryx species spawn iteratively during spawning season.  相似文献   

10.
EvoS is a consortium of evolutionary studies programs that can catalyze evolutionary training across the curriculum in higher education. This special issue of Evolution: Education and Outreach shows how the dictum “Nothing in biology makes sense except in the light of evolution” can be achieved within the biological sciences and expanded to include all human-related subjects, both for undergraduate education and faculty interactions, fulfilling the ideal of a liberal arts education and turning the university into a single intellectual community.  相似文献   

11.
Genetic control of aluminium tolerance in rye (Secale cereale L.)   总被引:4,自引:0,他引:4  
 Aluminium (Al) tolerance in roots of two cultivars (“Ailés” and “JNK”) and two inbred lines (“Riodeva” and “Pool”) of rye was studied using intact roots immersed in a nutrient solution at a controlled pH and temperature. Both the cultivars and the inbred lines analysed showed high Al tolerance, this character being under multigenic control. The inbred line “Riodeva” was sensitive (non-telerant) at a concentration of 150 μM, whereas the “Ailes” cultivar showed the highest level of Al tolerance at this concentration. The segregation of aluminium-tolerance genes and several isozyme loci in different F1s, F2s and backcrosses between plants of “Ailés” and “Riodeva” were also studied. The segregation ratios obtained for aluminium tolerance in the F2s analysed were 3 : 1 and 15 : 1 (tolerant : non-tolerant) while in backcrosses they were 1 : 1 and 3 : 1. These results indicated that Al tolerance is controlled by, at least, two major dominant and independent loci in rye (Alt1 and Alt3). Linkage analyses carried out between Al-tolerance genes and several isozyme loci revealed that the Alt1 locus was linked to the aconitase-1 (Aco1), nicotinamide adenine dinucleotide dehydrogenase-2 (Ndh2), esterase-6 (Est6) and esterase-8 (Est8) loci, located on chromosome arm 6RL. The order obtained was Alt1-Aco1-Ndh2-Est6-Est8. The Alt3 locus was not linked to the Lap1, Aco1 and Ndh2 loci, located on chromosome arms, 6RS, 6RL and 6RL respectively. Therefore, the Alt3 locus is probably on a different chromosome. Received: 18 March 1997 / Accepted: 21 March 1997  相似文献   

12.
Thermococcus litoralis (Tl) have been investigated by using the combination of EPR and variable-temperature magnetic circular dichroism (VTMCD) spectroscopies. The results reveal a [Fe4S4]2+,+ cluster (E m=−368 mV) that undergoes redox cycling between an oxidized form with an S=0 ground state and a reduced form that exists as a pH- and medium-dependent mixture of S=3/2 (g=5.4; E/D=0.33) and S=1/2 (g=2.03, 1.93, 1.86) ground states, with the former dominating in the presence of 50% (v/v) glycerol. Three distinct types of W(V) EPR signals have been observed during dye-mediated redox titration of as-isolated Tl FOR. The initial resonance observed upon oxidation, termed the “low-potential” W(V) species (g=1.977, 1.898, 1.843), corresponds to approximately 25–30% of the total W and undergoes redox cycling between W(IV)/W(V) and W(V)/W(VI) states at physiologically relevant potentials (E m=−335 and −280 mV, respectively). At higher potentials a minor “mid-potential” W(V) species, g=1.983, 1.956, 1.932, accounting for less than 5% of the total W, appears with a midpoint potential of −34 mV and persists up to at least +300 mV. At potentials above 0 mV, a major “high-potential” W(V) signal, g=1.981, 1.956, 1.883, accounting for 30–40% of the total W, appears at a midpoint potential of +184 mV. As-isolated samples of Tl FOR were found to undergo an approximately 8-fold enhancement in activity on incubation with excess Na2S under reducing conditions and the sulfide-activated Tl FOR was partially inactivated by cyanide. The spectroscopic and redox properties of the sulfide-activated Tl FOR are quite distinct from those of the as-isolated enzyme, with loss of the low-potential species and changes in both the mid-potential W(V) species (g=1.981, 1.950, 1.931; E m=−265 mV) and high-potential W(V) species (g=1.981, 1.952, 1.895; E m=+65 mV). Taken together, the W(V) species in sulfide-activated samples of Tl FOR maximally account for only 15% of the total W. Both types of high-potential W(V) species were lost upon incubation with cyanide and the sulfide-activated high-potential species is converted into the as-isolated high-potential species upon exposure to air. Structural models are proposed for each of the observed W(V) species and both types of mid-potential and high-potential species are proposed to be artifacts of ligand-based oxidation of W(VI) species. A W(VI) species with terminal sulfido or thiol ligands is proposed to be responsible for the catalytic activity in sulfide-activated samples of Tl FOR. Received: 9 September 1999 / Accepted: 17 February 2000  相似文献   

13.
This study presents data on behavioural acts performed by the Common Moorhen Gallinula chloropus in southern Brazil, and compares these with the behaviours previously reported for other populations. Focal observations of individuals were conducted in the municipality of Santa Maria, in the central region of the state of Rio Grande do Sul, Brazil. The sampling was done in 2-hour sessions, between January and March of 2007. A total of 20 behavioural acts, grouped in seven categories, were identified and described: locomotion (N = 5 acts), grooming (N = 4), intra-specific behaviour (N = 2), inter-specific behaviour (N = 3), foraging (N = 2), reproduction (N = 2) and rest (N = 2). Among the observed behaviours were acts that are not described in the literature such as greeting of offspring and some feeding acts. Regarding the use of habitat, we observed that this species has a preference for water or aquatic macrophytes, which is contrary to other reports. In the analysis of behavioural daily variation, overall behavioural categories did not vary significantly throughout the day, whereas we observed a significant difference in the use of categories during the periods 11:00 am–1:00 pm, 1:00–3:00 pm and 5:00–7:00 pm. The contrasting data between studies indicate that the variation between habitats and ecological interactions may generate different selective pressures on the behaviour of G. chloropus.  相似文献   

14.
The rhodophytes Hypnea cervicornis and Cryptonemia crenulata are abundant along the Brazilian coastline and are rich in nutrients. They may therefore be used as a source of protein in shrimp diets. The aim of the present study was to test this hypothesis. The experiment was conducted in a laboratory, where 10-day-old post-larvae aged underwent 7 days of acclimation in a 1,000 L tank. They were then kept in plastic aquariums, each containing 10 L, and 20 larvae were fed daily (10% of biomass) in four equal portions with one of four diets (five repetitions of each) for a period of 45 days. All diets contained 30% crude protein (isoprotein) and 300 kcal 100 g−1 (isocaloric), with different percentages of seaweed powder: Diet “A” 39%; Diet “B” 26%, Diet “C” 13%, and Diet “D” without seaweed (control diet). Algae were collected, rinsed, dried and ground up for the feed formulations. Weight of the animals was measured at the beginning of the experiment and at 15-day intervals to assess their growth. The physico-chemical variables of the water were measured every 2 days. Final biomass, biomass gain and specific growth rate (SGR) exhibited no significant differences between treatments (P > 0.05). Survival rate was equal under the four experimental conditions, being consistent within four decimal places 95.2% to 97.00% (P > 0.05). Diets “A” and “B”, with a greater content of algae, exhibited better feed conversion (1.79:1 and 1.82:1) than Diets “C” and “D” (2.04:1 and 2.08:1) (P < 0.05). The physical-chemical variables of the water showed no significant variation and remained within the standards necessary for the wellbeing of the animals. If sufficient biomass of beached algae can be practically and economically collected, it may be used as a component in the making of shrimp feed.  相似文献   

15.
Alternative male phenotypes in salmonine fishes arise from individuals that mature as larger and older anadromous marine-migrants or as smaller and younger freshwater residents. To better understand the processes influencing the expression of these phenotypes we examined the influences of growth in length (fork length) and whole body lipid content in rainbow trout (Oncorhynchus mykiss). Fish were sampled from the John Day River basin in northeast Oregon where both anadromous (“steelhead”) and freshwater resident rainbow trout coexist. Larger males with higher lipid levels had a greater probability of maturing as a resident at age-1+. Among males, 38% were maturing overall, and the odds ratios of the logistic model indicated that the probability of a male maturing early as a resident at age-1+ increased 49% (95% confidence interval (CI) = 23–81%) for every 5 mm increase in length and 33% (95% CI = 10–61%) for every 0.5% increase in whole body lipid content. There was an inverse association between individual condition and water temperature as growth was greater in warmer streams while whole body lipid content was higher in cooler streams. Our results support predictions from life history theory and further suggest that relationships between individual condition, maturation, and environmental variables (e.g., water temperature) are shaped by complex developmental and evolutionary influences.  相似文献   

16.
Macaranga (Euphorbiaceae) has received much ecological and evolutionary research attention as a genus that includes some of the most conspicuous pioneer trees of Southeast Asian tropical rainforests and because of its manifold associations with ants, including about 30 species that are obligate ant-plants (myrmecophytes). We used sequence data from three chloroplast DNA loci (ccmp5, ccmp6, atpB-rbcL) to assess phylogeographical patterns in species of Macaranga, section Pruinosae, sampled from various regions of Borneo and the Malay Peninsula. Forty-nine chloroplast DNA haplotypes (HT) were identified among 768 specimens from five species, Macaranga gigantea (N = 329; 23 HT), Macaranga pearsonii (N = 347; 21 HT), Macaranga puberula (N = 24; 4 HT), Macaranga hosei (N = 48; 6 HT), and Macaranga pruinosa (N = 20; 5 HT). Forty-one haplotypes were species-specific, whereas eight haplotypes were shared by two, three, or four species and occupied internal positions in a parsimony network. Population genetic parameters based on haplotype frequencies proved to be in a similar range in the non-myrmecophytic M. gigantea and in the ant-associated M. pearsonii, which have overlapping distributions in northern and eastern Borneo. A comparison of G ST and N ST values revealed a strong phylogeographic structure in both species, whereas colonization pathways suggested by the network topology were different. Both species exhibited similar levels of haplotypic diversity and moderate to high levels of population differentiation. There were no obvious indications for an influence of the symbiotic ant partners on the population structure of their host plants.  相似文献   

17.
A new species, Dolichopteryx rostrata, is described on the basis of a single specimen (66.2 mm in standard length) collected west of the Hebrides Islands, eastern North Atlantic Ocean. The new species is characterized by an elongate snout and head, small pouchlike eyes, an adipose fin, short dorsal fin base, anal fin base originating under dorsal fin base, a clear longitudinal suborbital brownish band extending forward from behind posterior margin of orbit to snout tip, and 41 (=26 + 15) vertebrae. Total fecundity is low; the ovarian eggs number only 473, despite the ovary having developed ova. Ovarian eggs could be clearly subdivided into an “undeveloped group” (0.1–0.7 mm diameter classes, n = 405) and a “developed group” (0.9–1.3 mm classes, n = 68), based on their frequency distribution. Supplementary material to this paper is available in electronic format at http://dx.doi.org/10.1007/s10228-005-0306-2  相似文献   

18.
Ten females (25–50 years of age) performed isometric shoulder flexions, holding the right arm straight and in a horizontal position. The subjects were able to see the rectified surface electromyogram (EMG) from either one of two electrode pairs above the upper trapezius muscle and were instructed to keep its amplitude constant for 15 min while gradually unloading the arm against a support. The EMG electrodes were placed at positions representing a “cranial” and a “caudal” region of the muscle suggested previously to possess different functional properties. During the two contractions, recordings were made of: (1) EMG root mean square-amplitude and zero crossing (ZC) frequency from both electrode pairs on the trapezius as well as from the anterior part of the deltoideus, (2) supportive force, (3) heart rate (HR) and mean arterial blood pressure (MAP), and (4) perceived fatigue. The median responses during the cranial isoelectric contraction were small as compared to those reported previously in the literature: changes in exerted glenohumeral torque and ZC rate of the isoelectric EMG signal of −2.81% · min−1 (P = 0.003) and 0.03% · min−1 (P= 0.54), respectively, and increases in HR and MAP of 0.14 beats · min−2 (P= 0.10) and 0.06 mmHg · min−1 (P= 0.33), respectively. During the contraction with constant caudal EMG amplitude, the corresponding median responses were −2.51% · min−1 (torque), 0.01% · min−1 (ZC rate), 0.31 beats · min−2 (HR), and 0.93 mmHg · min−1 (MAP); P=0.001, 0.69, 0.005, and 0.003, respectively. Considerable deviations from the “isoelectric” target amplitude were common for both contractions. Individuals differed markedly in response, and three distinct subgroups of subjects were identified using cluster analysis. These groups are suggested to represent different motor control scenarios, including differential engagement of subdivisions of the upper trapezius, alternating motor unit recruitment and, in one group, a gradual transition towards a greater involvement of type II motor units. The results indicate that prolonged low-level contractions of the shoulder muscles may in general be accomplished with a moderate metabolic stress, but also that neuromuscular adaptation strategies differ significantly between individuals. These results may help to explain why occupational shoulder-neck loads of long duration cause musculoskeletal disorders in some subjects but not in others. Accepted: 1 March 1997  相似文献   

19.
Benefits to females of short-term mating have recently been identified, and it has been suggested that women have evolved adaptations for this strategy. One piece of evidence supporting such a female adaptation would be that women find the experience of a one-night stand as affectively positive as men. Individuals (N = 1,743) who had experienced a one-night stand were asked to rate aspects of their “morning after” feelings (six positive and six negative). Women were significantly more negative and less positive than men. Although women did not especially view these relationships as a prelude to long-term relationships, they felt greater regret than men about having been “used.” Extra-pair copulations were rated more negatively, but not less positively, than singles’ experiences. There was no interaction between gender and mated status on positivity or negativity. Although, in terms of subsequent affective response, women do not seem well adapted to casual sexual encounters, it may be important to distinguish impelling sexual motivation preceding intercourse from later evaluations of the event. Menstrual cycle changes may also be important in altering the strength and target of sexual motivation.  相似文献   

20.
Environment perception by scorpions is an issue of great interest, and there is controversy about the use of pectines in this function. This paper investigates the mechanoreceptive function of pectines of the yellow scorpion Tityus serrulatus. The study was conducted in laboratory conditions from July 2003 to July 2004. Ninety females were maintained in six terraria (N = 15). Three of them were named “control” group (intact pectines) and the others “treatment” group (pectines covered with paraffin). Three experimental tests (an ethogram, a test of prey detection and a test of perception of substrate-borne vibrations) were performed to compare skills of animals with and without blocked pectines. The ethogram showed that treated individuals significantly reduced their exploratory activities, spent more time resting, and aggregated more than the control ones. Prey detection tests showed that the blocking of pectines made the yellow scorpions inefficient to detect and capture prey. Vibration tests showed that animals with blocked pectines also did not respond to the vibrations produced in the substrate, whereas the opposite occurred with the control group. These results suggest a mechanoreceptive function for T. serrulatus pectines, and show that the detection of ground vibrations by these structures is important for prey perception and orientation in the Brazilian yellow scorpion.  相似文献   

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