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51.
《Chronobiology international》2013,30(8):1168-1171
There are conflicting reports in the literature as to whether or not the circadian period in Syrian hamsters shortens with age, and those studies were conducted with small sample sizes. This report mines data from a large number of experiments resulting in more than 1000 measurements of circadian period in hamsters during aging up to 6 months, and this was correlated with both age and weight. Circadian period was calculated while hamsters were in running wheels in constant darkness. There is a weak correlation between hamster weight and circadian period, and there is significant shortening of circadian period during aging. 相似文献
52.
Alfred J. Lewy MD. PhD Jonathan S. Emens Bryan J. Lefler Krista Yuhas Angela R. Jackman 《Chronobiology international》2013,30(6):1093-1106
The specific circadian role proposed for endogenous melatonin production was based on a study of sighted people who took low pharmacological doses (500 µg) of this chemical signal for the “biological night”: the magnitude and direction of the induced phase shifts were dependent on what time of day exogenous melatonin was administered and were described by a phase‐response curve that turned out to be the opposite of that for light. We now report that lower (physiological) doses of up to 300 µg can entrain (synchronize) free‐running circadian rhythms of 10 totally blind subjects that would otherwise drift later each day. The resulting log‐linear dose‐response curve in the physiological range adds support for a circadian function of endogenous melatonin in humans. Efficacy of exogenous doses in the physiological range are of clinical significance for totally blind people who will need to take melatonin daily over their entire lifetimes in order to remain entrained to the 24 h day. Left untreated, their free‐running endocrine, metabolic, behavioral, and sleep/wake cycles can be almost as burdensome as not having vision. 相似文献
53.
《Chronobiology international》2013,30(8):1050-1065
We investigated the circadian synchronization/desynchronization (by field-study assessment of differences in period, τ, of 16 coexisting and well-documented rhythms) of 30 healthy firemen (FM) exposed to irregular, difficult, and stressful nocturnal work hours who demonstrated excellent clinical tolerance (allochronism). Three groups of FM were studied (A?=?12 FM on 24-h duty at the fire station; B?=?9 FM on 24-h duty at the emergency call center; C?=?9 day-shift administrative FM) of mostly comparable average age, body mass index, career duration, chronotype—morningness/eveningness, and trait of field dependence/independence. The self-assessed 16 circadian rhythms were (i) physiological ones of sleep-wake (sleep log), activity-rest (actography), body temperature (internal transmitter pill probe), right- and left-hand grip strength (hand dynamometer), systolic and diastolic blood pressure (BP) plus heart rate (ambulatory BP monitoring device); (ii) psychological ones (visual analog self-rating scales) of sleepiness, fatigue, fitness for work, and capacity to cope with aggressive social behavior; and (iii) cognitive ones of eye-hand skill and letter cancellation, entailing performance speed (tasks completed/unit time) and accuracy (errors). Data (4–6 time points/24?h; 2 591 480 values in total) were gathered continuously throughout two 8-d spans, one in winter 2010–2011 and one in summer 2011. Each of the resulting 938 unequal-interval time series was analyzed by a special power spectrum analysis to objectively determine the prominent τ. The desynchronization ratio (DR: number of study variables with τ?=?24.0?h/number of study variables?×?100) served to ascertain the strength/weakness of each rhythm per individual, group, and season. The field study confirmed, independent of group and season, coexistence of rather strong and weak circadian oscillators. Interindividual differences in DR were detected between groups and seasons (χ2, correlation tests, analysis of variance [ANOVA]). Moreover, in each group, both in winter and summer, a normal distribution was observed in the number of FM with rhythms with τ?=?24.0?h, e.g., ranging from 5/16 (large desynchronization) to 16/16 (no desynchronization). Such a normal distribution with intraindividual stability over time (i.e., seasons) is consistent with the hypothesis of an inherited origin of a differential propensity to circadian desynchronization and which is supported by the distribution of τs in winter and summer following the Dian-Circadian Genetic Model, i.e., with τ?=?24.0?h, τ?=?24.0?h?+?n(0.8?h), and τ?=?24.0?h???n(0.8?h). 相似文献
54.
Mesut Yeğen 《Ethnic and racial studies》2013,36(1):119-151
This article addresses the ways in which Turkish nationalism has perceived the Kurdish question. It is shown that both Turkish nationalism and the Kurdish question have passed through some paradigmatic moments in the twentieth century. This, I argue, has shaped the way that the Kurdish question has been perceived by Turkish nationalism. While the Kurdish question had been seen by Turkish nationalism mostly in terms of a fatal rivalry between the backward, pre-modern and tribal past and the prosperous present in the first half of the century, it was perceived in terms of a tension between the peripheral economy and national market in the fifties and sixties. In the 1970s, the Kurdish unrest was believed to be a product of communist incitement. Despite this impurity in perception, one thing has remained nearly unchanged for Turkish nationalism: Kurds could become Turkish. In other words, Turkish nationalism of the republican era has principally perceived Kurds as future-Turks. However, the signs in circulation at present indicate that the confidence of Turkish nationalism as to Kurds’ potential of becoming Turkish is not as firm as it used to be. At present, Turkish nationalism seems to be getting prepared to abandon its contention that Kurds are future-Turks. 相似文献
55.
56.
Factors affecting incidence and severity of leaf spot disease on lettuce caused by Septoria birgitae
In the 1990s during wet seasons a new disease causing brown leaf spots on lettuce (Lactuca sativa) was found for the first time in many lettuce‐growing areas of Austria and Germany. The causal agent, a new pathogenic species called Septoria birgitae, may be responsible for total crop loss. To study how temperature, inoculum density and leaf wetness period influence disease incidence and severity of leaf spot on lettuce caused by S. birgitae, we carried out in vivo experiments in growth chambers and in the field. Additionally, we evaluated the relevance of infected plant debris acting as a primary inoculum source in soil for subsequent crops. S. birgitae produces spores over a wide temperature range between 5°C and 30°C, and can infect plants at temperatures between 10°C and 30°C, with an optimum between 20°C and 30°C. Spores of S. birgitae at a density of at least 103 conidia mL–1 are essential for disease outbreak on lettuce. Because leaf wetness is crucial for releasing conidia from pycnidia, we studied the impact of leaf wetness duration on disease development under various temperature conditions. For relevant leaf spot disease development on lettuce in vivo, a leaf wetness duration of at least 24 h and temperatures higher than 10°C were necessary. Leaf spot disease development in the field required several leaf wetness periods longer than 20 h at approximately 15°C at the beginning of crop cultivation. Incorporating S. birgitae infected plant debris in soil as a primary inoculum was not relevant for leaf spot disease outbreak in the next year. However, in cases of continuous cropping of lettuce on the same field and in the same season, Septoria‐infected lettuce debris may become more relevant. 相似文献
57.
Sayali C. Ranade Sarfaraz Nawaz Arnab Chakrabarti Pierre Gressens Shyamala Mani 《Hormones and behavior》2013
"The goal of this study was to examine the effect of maternal iron deficiency on the developing hippocampus in order to define a developmental window for this effect, and to see whether iron deficiency causes changes in glucocorticoid levels. The study was carried out using pre-natal, post-natal, and pre + post-natal iron deficiency paradigm. Iron deficient pregnant dams and their pups displayed elevated corticosterone which, in turn, differentially affected glucocorticoid receptor (GR) expression in the CA1 and the dentate gyrus. Brain Derived Neurotrophic Factor (BDNF) was reduced in the hippocampi of pups following elevated corticosterone levels. Reduced neurogenesis at P7 was seen in pups born to iron deficient mothers, and these pups had reduced numbers of hippocampal pyramidal and granule cells as adults. Hippocampal subdivision volumes also were altered. The structural and molecular defects in the pups were correlated with radial arm maze performance; reference memory function was especially affected. Pups from dams that were iron deficient throughout pregnancy and lactation displayed the complete spectrum of defects, while pups from dams that were iron deficient only during pregnancy or during lactation displayed subsets of defects. These findings show that maternal iron deficiency is associated with altered levels of corticosterone and GR expression, and with spatial memory deficits in their pups." 相似文献
58.
2007-2012 年佛冈县稻飞虱灯下发生期及种群数量动态分析 总被引:1,自引:0,他引:1
明确佛冈县稻飞虱灯下发生期及灯诱种群数量动态,对当地稻飞虱的预测预报和防治工作具有重要意义.根据佛冈县2007-2012年白背飞虱和褐飞虱的灯诱数据,分析了该县白背飞虱和褐飞虱的灯下始见日、终见日、发生期及灯诱量等.结果表明在佛冈地区,白背飞虱和褐飞虱混合发生;白背飞虱的灯下始见日集中在3月底至4月上旬,明显比褐飞虱早一个月,终见日均在10月下旬,差别不大;稻飞虱在早稻和晚稻期间均会出现大小不一的灯诱高峰,早稻期间白背飞虱高峰期集中在5月中旬至6月中旬,褐飞虱灯诱高峰期较迟,主要在7月中旬前后;晚稻期间向背飞虱高峰期大多在9月上旬至10月上旬,褐飞虱高峰期在10月份;早稻期间,白背飞虱的灯诱量占绝对优势,晚稻期间褐飞虱的灯诱量上升,与白背飞虱灯诱量基本持平.因此,佛冈县稻飞虱的灯下发生期及种群数量动态在一定程度上可反映当地稻飞虱的发生情况. 相似文献
59.
Mechanism of Developmental Effects in Rats Caused by an N‐Phenylimide Herbicide: Transient Fetal Anemia and Sequelae during Mid‐to‐Late Gestation
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60.
Fringes of the empire: Diet and cultural change at the Roman to post‐Roman transition in NW Iberia
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A growing number of paleodiet investigations over recent years have begun to reveal the stark dietary differences that existed between regions of the Roman Empire, as well as significant changes in subsistence strategies after its fall. The present study explores the dietary changes at the Roman to post‐Roman (Germanic) transition in the Northwest Iberian Peninsula, in order to improve our understanding of the changes that occurred at end of the Roman Empire in different regions across Europe and to also consider the influence of climate had on them. The carbon and nitrogen stable isotope investigation in bone collagen from A Lanzada, NW Spain (100–700 AD), which was an important commercial, coastal settlement has been presented. A human sample of 59 individuals, 6 of them subadults, is compared with 31 faunal specimens, which include a number of marine fish. Isotope data for the terrestrial fauna reveal the influence of the sea on the local isotope baseline. Analysis of the human samples indicates a mixed marine‐terrestrial diet. A shift in mean human δ13C values from ?16.7‰ to ?14.3‰ provides clear evidence for a significant change in diet in the post‐Roman period, probably through the intensification of both marine resources exploitation and C4‐plant consumption (presumably millet). A deterioration of paleoenvironmental conditions, together with a poor socioeconomic situation and the arrival of new people, the Sueves, who brought a new political and socioeconomic system have been discussed as the main causes for the dietary modification in post‐Roman times. 相似文献