1,012,864 research outputs found

    On the genus "Asplenium" in the Iberian Peninsula"

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    The Asplenium species recorded from the Iberian peninsula comprise diploids and tetraploids, and of the latter, both auto- and allotetraploids occur. Evidence from the meiotic pairing behaviour of the chromosomes in synthetic hybrids is adduced to show how the mode of origin and interrelationships of such species can be elucidated, and specific reference is made to Asplenium foresiense, A. majoricum, A. petrarchae and A. billotii. The suggested occurrence of autopolyploidy in Asplenium cuneifolium is also discussed. Evidence is presented which shows that in the British Isles and Corsica serpentine plants previously regarded as autotetraploid derivatives of A. cuneifolium are in fact allotetraploid and almost certainly just specialized serpentine forms of Asplenium adiantum-nigrum. It is suggested that such forms of A. adiantum-nigrum could occur also on serpentine rocks elsewhere in western Europe, for example, in Spain and France.Las especies del genero Asplenium, registradas en la Peninsula Ibérica, comprenden citotipos diploides y tetraploides, siendo estos últimos tanto autotetraploides como alotetraploides. Del apareamiento miótico de los cromosomas en los híbridos sintéticos se aducen pruebas para mostrar como se pueden dilucidar el modo de origen y las interrelaciones de tales especies, y se hace referencia específica a Asplenium foresiense, A. majoricum, A. petrarchae y A. billotii. También se discute la cuestión de la autopoliploidía de A. cuneifolium que habia sido sugerida previamente. Se ofrecen datos experimentales que muestran que en las Islas Británicas y en Córcega las plantas que crecen sobre serpentinas, anteriormente consideradas como un derivado autotetraploidal de A. cuneifolium, son en realidad alotetraploides y, casi con certeza, no son más que formas serpentinícolas especializadas de A. adiantum-nigrum. Se sugiere que tales formas de A. adiantum-nigrum pueden existir también sobre serpentinas en otras partes de Europa occidental, por ejemplo, en España o Francia

    The Natural History of Insomnia: Acute Insomnia and First-onset Depression

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    Study Objectives: While many studies have examined the association between insomnia and depression, no studies have evaluated these associations 1) within a narrow time frame, 2) with specific reference to acute & chronic insomnia, and 3) using polysomnography. In the present study, the association between insomnia and first-onset depression was evaluated taking into account these considerations. Design: A mixed-model inception design. Setting: Academic research laboratory. Participants: Fifty-four individuals (acute insomnia (n=33), normal sleepers (n=21)) with no reported history of a sleep disorder, chronic medical condition, or psychiatric illness. Interventions: N/A Measurements and Results: Participants were assessed at baseline (two nights of polysomnography and psychometric measures of stress and mood) and insomnia and depression status were reassessed at 3 months. Individuals with acute insomnia exhibited more stress, poorer mood, worse subjective sleep continuity, increased N2 sleep and decreased N3 sleep. Individuals that transitioned to chronic insomnia exhibited (at baseline) shorter REM Latencies and reduced N3 sleep. Individuals that exhibited this pattern, in the transition from acute to chronic insomnia, were also more likely to develop first-onset depression (9.26%) as compared to those who remitted from insomnia (1.85%) or were normal sleepers (1.85%). Conclusion: The transition from acute to chronic insomnia is presaged by baseline differences in sleep architecture that have, in the past, been ascribed to Major Depression, either as heritable traits or as acquired traits from prior episodes of depression. The present findings suggest that the “sleep architecture stigmata” of depression may actually develop over the course transitioning from acute to chronic insomnia

    Differential Effects of Psychological and Physical Stress on the Sleep Pattern in Rats

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    In the present study, we investigated the acute effects of 2 different kinds of stress, namely physical stress (foot shock) and psychological stress (non-foot shock) induced by the communication box method, on the sleep patterns of rats. The sleep patterns were recorded for 6 h immediately after 1 h of stress. Physical and psychological stress had almost opposite effects on the sleep patterns: In the physical stress group, hourly total rapid eye movement (REM) sleep and total non-REM sleep were significantly inhibited, whereas psychological stress enhanced hourly total REM sleep but not total non-REM sleep. Further results showed that total REM sleep, total non-REM sleep, total sleep and the total number of REM sleep episodes in 5 h were reduced, and that sleep latency was prolonged compared to the control group. On the other hand, in the psychological stress group, the total REM sleep in 5 h was increased significantly due to the prolongation of the average duration of REM sleep episodes and reduced REM sleep latency. In addition, the plasma of corticosterone increased significantly after physical stress but not after psychological stress. These results suggested that the sleep patterns, particularly the patterns of REM sleep following physical and psychological stress, are probably regulated by 2 different pathways.</p

    Teens and sleep

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    Sleep is a very important part of the day for everyone. There are many reasons why people should be striving to get the sleep they need. However, many people are skipping out on an hour or two of the recommended time. This presentation is focused on teenage students, how their loss of sleep affects them and why they aren’t getting the amount of sleep they need. ● Teens aged 13–18 should sleep 8–10 hours per day, and 72.7% of high school students don’t get this amount. ● Many negative effects of sleep deprivation. ● Having a normal sleep schedule is just as important as getting enough sleep. ● Light plays a big role in resetting our sleep rhythm. ● Final hours of REM sleep are most important for retaining information. ● On average as children get older they begin to go to sleep later, with the same wake up time. ● Students don’t go to sleep earlier for earlier wake up times

    Sleep, Sleep, and More Sleep

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    Postcard from Taylor Brown, during the Linfield College Semester Abroad Program at Oslo Metropolitan University in Norwa

    The Association between Sleep Problems, Sleep Medication Use, and Falls in Community-Dwelling Older Adults: Results from the Health and Retirement Study 2010

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    Background. Very few studies have assessed the impact of poor sleep and sleep medication use on the risk of falls among community-dwelling older adults. The objective of this study was to evaluate the association between sleep problems, sleep medication use, and falls in community-dwelling older adults. Methods. The study population comprised a nationally representative sample of noninstitutionalized older adults participating in the 2010 Health and Retirement Study. Proportion of adults reporting sleep problems, sleep medication use, and fall was calculated. Multiple logistic regression models were constructed to examine the impact of sleep problems and sleep medication use on the risk of falls after controlling for covariates. Results. Among 9,843 community-dwelling older adults, 35.8% had reported a fall and 40.8% had reported sleep problems in the past two years. Sleep medication use was reported by 20.9% of the participants. Older adults who do have sleep problems and take sleep medications had a significant high risk of falls, compared to older adults who do not have sleep problems and do not take sleep medications. The other two groups also had significantly greater risk for falls. Conclusion. Sleep problems added to sleep medication use increase the risk of falls. Further prospective studies are needed to confirm these observed findings
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