Shift work and sex are variants across Karolinska Sleep Questionnaire and the application of linking analysis as a step forward using Item Response Theory

The frequency of sleep disturbances is considerably higher in the night and shift workers and in females than in day workers and males, respectively. However, a subjective sleep scale must be invariant across these groups, independently of the level of their members on the scale. This study is aimed to test the invariance of the Karolinska Sleep Questionnaire’s (KSQ) items by shift work and sex. We used the data from a census that covered more than 90% (N = 1648) of the nurses from the main institute of the largest public hospital complex of Brazil. Firstly, we intend to find the KSQ’s dimensionality using factorial analysis and Item Response Theory (IRT) performed by Graded Response Model. Differential Item Functioning (DIF) was the technique used to test the invariance of each KSQ’s dimensions. In case of variance detection, we applied the linking analysis. Intending to test the KSQ’s consistency with external variables, we assessed correlations between KSQ’s dimensions with health variables, i.e., self-reported health status and musculoskeletal pain. We have found one scale and two subscales from one general and another bidimensional factor structure of the KSQ, respectively. In these dimensions, the KSQ’s items fitted well to the IRT and we have identified DIF by shift work. However, we have found DIF by sex just in one item on the general factor. Linking analysis showed as a possible step forward in the variance issue placing on to the same scale the shift work groups in the items with DIF. All correlations between KSQ’s dimensions with health variables were significant. Our findings allow us to argue that KQS’s items were variant by shift work and sex in a nursing staff census from the largest public hospital complex of Brazil, but we can go on using linking analysis. This could be used as an evidence for the construct validity should go beyond the traditional dimensionality assessment. The dimensionalities of KSQ fit well for other population but individuals living in Scandinavian countries.     

Clinical significance of social jetlag in patients with excessive daytime sleepiness

ABSTRACT

Social jetlag has recently attracted attention as the circadian misalignment between biological and social clocks. We aimed to examine social jetlag and its effect on daytime sleepiness and daily functions in patients with narcolepsy, behaviorally induced insufficient sleep syndrome (BIISS) and delayed sleep-wake phase disorder (DSPD). The levels of social jetlag (SJL_mid) and sleep-corrected social jetlag (SJL_sc) were calculated for each patient, and the effect of these social jetlag-related parameters on daytime sleepiness and daily functions were examined. Objective sleepiness measured by the mean sleep latency in the multiple sleep latency test, subjective sleepiness assessed by the Epworth sleepiness scale (ESS), health-related quality of life (HRQoL) assessed by the SF-8 health survey, and incidences of mistakes in daily activities, traffic accidents and near-miss events related to daytime sleepiness were compared among the narcolepsy (n = 39), BIISS (n = 87) and DSPD (n = 28) groups. Both SJL_mid and SJL_sc showed a negative correlation with physical HRQoL in patients with narcolepsy and a positive correlation with the ESS score in patients with DSPD. In patients with BIISS, SJL_sc reflected sleep loss rather than circadian misalignment; moreover, SJL_sc was not associated with daytime sleepiness and daily functions. Social jetlag was not associated with incidences of mistakes in daily activities, traffic accidents and near-miss events.

The state of social jetlag and its association with daily functions differed among the narcolepsy, BIISS and DSPD groups. Social jetlag represented sleep debt in BIISS, circadian misalignment in narcolepsy and both in DSPD. Our results thus show that the clinical manifestations and significance of social jetlag differ depending on the underlying sleep disorders.     

Rest-activity rhythm in breast cancer survivors: an update based on non-parametric indices

ABSTRACT

Recently we evaluated by actigraphy the rest-activity circadian rhythm (RAR) in breast cancer (BC) survivors at 5 years from primary diagnosis, as well as in a control group with similar age and body mass index (BMI). RAR, analyzed by Cosinor method, resulted significantly different in BC survivors compared to healthy subjects: BC survivors showed lower values of MESOR and Amplitude (A), while acrophase (φ) was similar in the two groups.

Now, using non-parametric methods we have detected Interdaily Stability (IS), Intradaily Variability (IV), nocturnal activity (L5), and daily activity (M10) on the same sample of previous study: 15 BC survivors at 5 years from the primary diagnosis (mean age = 56.7 ± 6.6 yrs; mean BMI = 24.5 ± 3.8 Kg/m²) and 13 healthy controls (mean age = 54.4 ± 7.2 yrs; mean BMI = 25.2 ± 2.8 Kg/m²).

The non-parametric indices showed that in BC-group IV was significantly higher than in Ctrl-group (0.86 vs. 0.65 a.u. in BC and Ctrl, respectively; p <.01), while L5 (11.27 vs. 34.41 a.c. in BC and Ctrl, respectively; p <.0001) and M10 (326.82 vs. 428.07 a.c. in BC and Ctrl, respectively; p <.01) were significantly lower compared to Ctrl-group.

The data suggest that BC patients need constant clinical assessment of RAR characteristics along the years following the primary diagnosis. The analysis of RAR in all its components, parametric and non-parametric, is important to detect alterations in the sleep-wake cycle and can be useful for developing new strategies for health protection, such as structured and tailored physical activity programs, to improve circadian activity level in order to raise the quality of life in BC survivors.     

Convergent and construct validity and test–retest reliability of the Caen Chronotype Questionnaire in six languages

ABSTRACT

Chronotype questionnaires provide a simple and time-effective approach to assessing individual differences in circadian variations. Chronotype questionnaires traditionally focused on one dimension of chronotype, namely its orientation along a continuum of morningness and eveningness. The Caen Chronotype Questionnaire (CCQ) was developed to assess an additional dimension of chronotype that captures the extent to which individual functioning varies during the day (amplitude). The aim of this study was to provide a multilanguage validation of the CCQ in six world regions (Arabic, Dutch, German, Italian, Portuguese and Spanish). At Time 1, a total of 2788 participants agreed to take part in the study (Arabic, n = 731; Dutch, n = 538; German, n = 329; Italian, n = 473; Portuguese, n = 361; Spanish, n = 356). Participants completed an assessment of the CCQ together with the Morningness-Eveningness Questionnaire (MEQ; Horne & Ostberg 1976) as well as questions related to factors theoretically related to chronotype (age, shift work, physical activity, sleep parameters and coffee consumption). One month later, participants again completed the CCQ. Results showed that the two-factor structure (morningness-eveningness and amplitude) of the CCQ could be replicated in all six languages. However, measurement invariance could not be assumed regarding the factor loadings across languages, meaning that items loaded more on their factors in some translations than in others. Test–retest reliability of the CCQ ranged from unacceptable (German version) to excellent (Dutch, Portuguese). Convergent validity was established through small–medium effect size correlations between the morningness-eveningness dimension of the CCQ and the MEQ. Taken together, our findings generally support the use of the translated versions of the CCQ. Further validation work on the CCQ is required including convergent validation against physiological markers of sleep, health and well-being.     

Perceived sleep quality among edentulous elders

doi: 10.1111/j.1741‐2358.2010.00426.x Perceived sleep quality among edentulous elders Background: Anatomical changes associated with edentulism are thought to disturb seniors’ sleep. Objectives: (1) To determine sleep quality and daytime sleepiness of edentulous elders. (2) To examine the association between oral health‐related quality of life and sleep quality. Methods: Data were collected at a 1‐year follow‐up from 173 healthy edentulous elders who had participated in a randomised controlled trial and randomly received two types of mandibular prosthesis. Subjective sleep quality was assessed using the Pittsburgh Sleep Quality Index (PSQI, range 0–21), with higher scores indicating poorer sleep quality. The Epworth Sleepiness Scale (ESS) was used to measure the level of perceived daytime sleepiness, and scores ≥10 indicated sleepiness. Results: The mean global PSQI and ESS scores were 4.7 ± 3.5 and 5.3 ± 3.9. There were no differences in sleep quality or sleepiness between those who wore their dentures at night and those who did not. Elders with frequent denture problems were sleepier during the day than those with fewer problems (p = 0.0034). General health (p = 0.02) and oral health‐related quality of life (p = 0.001) are significant predictors of sleep quality. Conclusion: Healthy edentulous elders, independent of nocturnal wearing of their prosthesis, are good sleepers. Maintaining high oral health quality of life could contribute to better sleep.     

Preliminary findings for the validity of the Morningness–Eveningness-Stability Scale improved (MESSi): Correlations with activity levels and personality

Aim of the present study is an additional validation of the Morningness–Eveningness-Stability Scale improved (MESSi). We screened a total of 97 German students using the reduced Morningness–Eveningness Questionnaire (rMEQ) to identify a subsample (N = 42) of definite morning and evening types (31% males, mean age: 24.8 ± 5.8?years). The participants provided information about their sleep–wake rhythm (diary), personality traits (questionnaire) and experienced actigraphic monitoring. Correlations of the MESSi components “Morning affect subscale” (MA) (r = 0.91, p < 0.01) and “Eveningness subscale” (r = ?0.87, p < 0.01) with the rMEQ showed good convergent validity. MA was also significantly negatively correlated with the acrophase and the midpoint of sleep as measured by actigraphy.     

Factor scoring models of the Pittsburgh Sleep Quality Index: a comparative confirmatory factor analysis

The Pittsburgh Sleep Quality Index (PSQI) is a rigorously validated questionnaire with extensive use in sleep assessment. Findings from numerous factor analytic studies of the PSQI have been interpreted to support a heterogeneous factor structure model for the test. Nevertheless, the literature continues to lack a focused evaluation of whether this heterogeneous factor structure is justified. A consideration of this issue led to a conclusion that a closer analysis of the PSQI’s factor structure was merited. To address this need a comparative confirmatory factor analysis for assessing the performance of the accepted factors models of the PSQI was conducted. A sample of university students (n = 418), age = 20.92 ± 1.81 years, BMI = 23.30 ± 2.57 kg/m² completed the multi-structured sleep survey at Jamia Millia Islamia, New Delhi, India. Seventeen putative factor structures (three 1-Factor, eight 2-Factor, and six 3-Factor) of the PSQI from the existing literature were selected for analysis. Fourteen models (82.35%) had almost similar values for model fit indices. Two models were misfits, and one model was a poor fit. The two misfit models incorporated gender and age as covariates. The third poor fit model was used to produce a unique path diagram, which made it distinct from the remaining 16 models. The overlapping values in the fit range of the model fit indices did not support the often projected heterogeneous factor structures of the PSQI for the vast majority of the models.     

Psychosocial Work Characteristics Predicting Daytime Sleepiness in Day and Shift Workers

Characteristics of work organization other than working time arrangements may contribute importantly to daytime sleepiness. The present study was designed to identify the psychosocial factors at work that predict daytime sleepiness in a sample of day and shift workers. Participants working at a pulp and chemical factory completed an annual questionnaire regarding psychosocial factors at work using the U.S. National Institute for Occupational Safety and Health Generic Job Stress Questionnaire (i.e., quantitative workload, variance in workload, job control, support from supervisor, coworkers, or family/friends, job satisfaction, and depressive symptoms), as well as daytime sleepiness (through the Epworth Sleepiness Scale [ESS]) and sleep disturbances for three years starting in 2002 (response rates, 94.6–99.0%). The present analysis included 55 day workers (11 women) and 57 shift workers (all men) who participated in all three years of the study, worked under the same work schedule throughout the study period, and had no missing data on any of the daytime sleep items. A repeated‐measures analysis of covariance (ANCOVA) was used to test the effects of work schedule (day vs. shift work) and psychosocial factors at work in 2002 on the ESS scores in subsequent years, with sleep duration, insomnia symptoms, chronic diseases, and sleepiness levels at baseline as covariates. Given significant and near‐significant interactions of work schedules with psychosocial factor or study year, the ANCOVA, with the factors of psychosocial work characteristics and study year, was performed by type of work schedule. The results indicated a significant main effect of psychosocial work characteristics (p=0.010, partial ?²=0.14) and an almost significant main effect of study year (p=0.067, partial ?²=0.06) and interaction between psychosocial work characteristics and study year (p=0.085, partial ?²=0.06) for variance in workload among the day work group. The day workers reporting high variance in workload in 2002 exhibited significantly higher ESS scores in 2003 and 2004 than did those reporting low variance in workload. The ANCOVA for the shift work group showed a main effect of psychosocial work characteristics for job satisfaction (p=0.026, partial ?²=0.10) and depressive symptoms (p=0.094, partial ?²=0.06) with the interaction between psychosocial work characteristics and study year for job satisfaction (p=0.172, partial ?²=0.04) and depressive symptoms (p=0.035, partial ?²=0.07). The shift workers with low job satisfaction and high symptoms of depression in 2002 showed significantly greater ESS scores in 2003 and/or 2004 than did those with opposite characteristics. These results may suggest a potential predictive value of variance in workload for day workers as well as job satisfaction and depressive symptoms for shift workers with respect to daytime sleepiness. The present findings may imply that redesigning these aspects of work environment would be of help in managing daytime sleepiness.     

Anxiety symptomatology,sex and chronotype: The mediational effect of diurnal sleepiness

ABSTRACT

Diurnal subjective sleepiness has been associated with a large number of negative outcomes, such as increased risk of accidents and development of mental disorders as depression and anxiety. However, the role of the diurnal subjective sleepiness as a mediator is poorly understood. The goal of the present study was to examine the role of diurnal subjective sleepiness as a mediator of the relationship between sex, chronotype and anxiety symptoms in healthy young adults. Four-hundred and sixty-seven healthy young adults (64.8% females, age range 18–32 years, mean 20.7, ±2.3) were evaluated with validated and widely used scales for the measurement of diurnal sleepiness, anxiety symptoms and morningness–eveningness preference. We have found that diurnal subjective sleepiness correlated with anxiety symptoms when evaluated both in the total sample and within chronotypes. This association was more important in females than in males (p < 0.0001). Regarding chronotype, only for morning-types, diurnal subjective sleepiness was a significant mediator of the relationship between sex and anxiety symptoms. This is the first study that examines the mediator role of diurnal subjective sleepiness in the known relationship between sex and anxiety symptoms, and adds new evidence about the effect of the chronotype on sleep problems and mental health. Although future work is required, our results have important implications for clinical settings and public health interventions.     

Effects of sports training on sleep characteristics of Asian adolescent athletes

Adolescents are predisposed to poorer quality of sleep and experience shortened sleep durations, with these trends being more pronounced amongst Asians. Even though sleep is crucial for athletic recovery, there is a dearth of the literature on the sleep patterns of Asian adolescent athletes. The purpose of this study was to examine the effects of different intensities of sports training on sleep patterns in adolescent athletes, and to describe novel sleep data and daytime sleepiness amongst Asian adolescents who were high-level athletes. Those athletes (age 14.8 ± 0.9 years) in higher-intensity sports showed significantly more deep sleep, less light sleep and waketime after sleep onset. Actigraphically determined bedtimes and waketimes were significantly delayed on weekends, when mean total sleep time was also significantly longer. There was a large effect for an increased daytime sleepiness in high-intensity sport athletes. These findings highlight the phenomenon of social jet lag in Asian adolescent student-athletes.     

Proposal of cutoff points for pediatric daytime sleepiness scale to identify excessive daytime sleepiness

The objective of the present study was to propose cutoff points for the Pediatric Daytime Sleepiness Scale (PDSS) through sensitivity and specificity analyses in order to identify excessive daytime sleepiness, considering parameters such as duration and quality of sleep, health perception, stress control and depressive moods (feelings of sadness) in adolescents. A total of 1,132 adolescents, aged 14–19 years old, of both sexes, from the public high school of São José – SC, answered the questionnaire with information on age, daytime sleepiness, sleep duration, health perception, stress management, depressive moods (feelings of sadness) and quality of sleep. The Receiver Operating Characteristic (ROC) curve was used to estimate cutoff points considering the sensitivity and specificity values ??that best identify adolescents with excessive daytime sleepiness, using independent variables as a reference. The majority of the sample was female (54.2%), aged 14–16 years. The girls presented worse quality of sleep (66.4%), and the boys had a more positive perception of health (74.8%), better stress control (64.8%) and lower depressive moods (feelings of sadness) (63.3%). The largest area in the ROC curve was the one that considered sleep quality as a parameter in both sexes (area of the curve = 0.709 and 0.659, respectively, for boys and girls, p < 0.001). Considering sleep quality as a reference, the cutoff point for excessive daytime sleepiness was 15 points. The other parameters used were also significant (p < 0.005). Poor sleep quality was the parameter most strongly related to daytime sleepiness, and a cutoff of 15 points for the PDSS for both sexes should be used in the definition of excessive daytime sleepiness. For the other parameters, stress management, depressive mood (feelings of sadness) and health perception, different cutoff points are suggested for boys and girls.     

Intra-individual variability in the sleep of senior and junior rugby league athletes during the competitive season

This study examined the sleep intra-individual variability (IIV) of rugby league athletes across senior and junior levels during one week of the competitive season. Forty-five rugby league athletes across elite senior, sub-elite senior and elite junior levels each wore actigraphy monitors for seven days during the competitive season, and completed a subjective sleep diary each morning upon waking. Linear mixed models were used to assess differences in sleep measures between playing levels. Intra-individual standard deviations for each sleep measure were calculated for each athlete to determine their respective IIV, allowing differences in IIV between groups to be assessed. Elite junior athletes went to bed later (ES = 0.94 ± 0.50, p < 0.05) and woke later than elite senior athletes (ES = 0.94 ± 0.40, p < 0.05), while also displaying greater IIV when considering time in bed (ES = 1.14 ± 0.60, p < 0.05) and sleep duration (ES = 1.53 ± 0.64, p < 0.05) compared with elite senior athletes. Similarly, IIV was more pronounced in elite junior players for time in bed (ES = 0.88 ± 0.60, p < 0.05) and sleep duration (ES = 1.03 ± 0.64, p < 0.05) compared with sub-elite senior athletes. Despite this, elite junior athletes still obtained sufficient sleep duration, efficiency and quality. The outcomes of this investigation show a distinct difference in the habitual sleep-wake patterns of senior and junior rugby league athletes, and show how sleep IIV differs between playing levels in rugby league.     

Effects of land use on sources and ages of inorganic and organic carbon in temperate headwater streams

The amounts, sources and relative ages of inorganic and organic carbon pools were assessed in eight headwater streams draining watersheds dominated by either forest, pasture, cropland or urban development in the lower Chesapeake Bay region (Virginia, USA). Streams were sampled at baseflow conditions six different times over 1 year. The sources and ages of the carbon pools were characterized by isotopic (δ¹³C and ?¹⁴C) analyses and excitation emission matrix fluorescence with parallel factor analysis (EEM–PARAFAC). The findings from this study showed that human land use may alter aquatic carbon cycling in three primary ways. First, human land use affects the sources and ages of DIC by controlling different rates of weathering and erosion. Relative to dissolved inorganic carbon (DIC) in forested streams which originated primarily from respiration of young, ¹⁴C-enriched organic matter (OM; δ¹³C = ?22.2 ± 3 ‰; ?¹⁴C = 69 ± 14 ‰), DIC in urbanized streams was influenced more by sedimentary carbonate weathering (δ¹³C = ?12.4 ± 1 ‰; ?¹⁴C = ?270 ± 37 ‰) and one of pasture streams showed a greater influence from young soil carbonates (δ¹³C = ?5.7 ± 2.5 ‰; ?¹⁴C = 69 ‰). Second, human land use alters the proportions of terrestrial versus autochthonous/microbial sources of stream water OM. Fluorescence properties of dissolved OM (DOM) and the C:N of particulate OM (POM) suggested that streams draining human-altered watersheds contained greater relative contributions of DOM and POM from autochthonous/microbial sources than forested streams. Third, human land uses can mobilize geologically aged inorganic carbon and enable its participation in contemporary carbon cycling. Aged DOM (?¹⁴C = ?248 to ?202 ‰, equivalent¹⁴C ages of 1,811–2,284 years BP) and POM (?¹⁴C = ?90 to ?88 ‰, ¹⁴C ages of 669–887 years BP) were observed exclusively in urbanized streams, presumably a result of autotrophic fixation of aged DIC (?297 to ?244 ‰, ¹⁴C age = 2,251–2,833 years BP) from sedimentary shell dissolution and perhaps also watershed export of fossil fuel carbon. This study demonstrates that human land use may have significant impacts on the amounts, sources, ages and cycling of carbon in headwater streams and their associated watersheds.     

Melatonin ingestion after exhaustive late-evening exercise improves sleep quality and quantity,and short-term performances in teenage athletes

ABSTRACT

The present study aimed to explore the effects of a single 10-mg dose of melatonin (MEL) administration after exhaustive late-evening exercise on sleep quality and quantity, and short-term physical and cognitive performances in healthy teenagers. Ten male adolescent athletes (mean ± SD, age = 15.4 ± 0.3 years, body-mass = 60.68 ± 5.7 kg, height = 167.9 ± 6.9 cm and BMI = 21.21 ± 2.5) performed two test sessions separated by at least one week. During each session, participants completed the Yo-Yo intermittent-recovery-test level-1 (YYIRT-1) at ~20:00 h. Then, sleep polysomnography was recorded from 22:15 min to 07:00 h, after a double blind randomized order administration of a single 10-mg tablet of MEL (MEL-10 mg) or Placebo (PLA). The following morning, Hooper wellness index was administered and the participants performed the Choice Reaction Time (CRT) test, the Zazzo test and some short-term physical exercises (YYIRT-1, vertical and horizontal Jumps (VJ; HJ), Hand grip strength (HG), and five-jump test (5-JT)). Evening total distance covered in the YYIRT-1 did not change during the two conditions (p > 0.05). Total sleep time (Δ = 24.55 mn; p < 0.001), sleep efficiency (Δ = 4.47%; p < 0.001), stage-3 sleep (N3 sleep) (Δ = 1.73%; p < 0.05) and rapid-eye-movement sleep (Δ = 2.15%; p < 0.001) were significantly higher with MEL in comparison with PLA. Moreover, sleep-onset-latency (Δ = –8.45mn; p < 0.001), total time of nocturnal awakenings after sleep-onset (NA) (Δ = –11 mn; p < 0.001), stage-1 sleep (N1 sleep) (Δ = –1.7%; p < 0.001) and stage-2 sleep (N2 sleep) (Δ = ?1.9%; p < 0.05) durations were lower with MEL. The Hooper index showed a better subjective sleep quality, a decrease of the subjective perception of fatigue and a reduced level of muscle soreness with MEL. Moreover, MEL improved speed and performance but not inaccuracy during the Zazzo test. CRT was faster with MEL. Morning YYIRT-1 (Δ = 82 m; p < 0.001) and 5-JT (Δ = 0.08 m; p < 0.05) performances were significantly higher with MEL in comparison with PLA. In contrast, HG, VJ and HJ performances did not change during the two conditions (p > 0.05). The administration of a single dose of MEL-10 mg after strenuous late-evening exercise improved sleep quality and quantity, selective attention, subjective assessment of the general wellness state, and some short-term physical performances the following morning in healthy teenagers.     

Association between GSTP1, GSTM1 and GSTT1 polymorphisms involved in xenobiotic metabolism and head and neck cancer development

Polymorphisms in the glutathione S-transferase superfamily genes that encodes enzymes involved in the phase II xenobiotic metabolism may lead head and neck cancer development. In this study we investigate the association of A313G and C341T GSTP1 polymorphisms, GSTM1 and GSTT1 null genotypes in the head and neck cancer development, interactions between these polymorphisms,the tumor histopathologic parameters and risk factors (smoking and drinking) were also evaluated in the case–control study. 775 individuals (261 patients/514 controls) were included in the study. Molecular analyzes were performed by PCR and PCR–RFLP; and statistical analyzes by Chi square and multiple logistic regression. Chi square test showed that only the genotype frequencies for GSTM1 and GSTT1 were in Hardy–Weinberg disequilibrium in both groups. Significant results with p ≤ 0.05 showed that age ≥ 48 years (OR = 11.87; 7.55–18.65), smoking (OR = 4.25; 2.70–6.69), drinking (OR = 1.59; 1.02–2.46) were possible predictors for the head and neck cancer development and the presence of A313G GSTP1 polymorphism (OR = 0.62; 0.42–0.92) decreased the risk for this disease. Individuals with the 313AG/GG GSTP1 and age ≥ 48 years (OR = 0.59; 0.38–0.91), male gender (OR = 0.54; 0.35–0.83), smokers (OR = 0.63; 0.40–0.99) and drinkers (OR = 0.57; 0.35–0.95); the GSTM1 null genotype and age < 48 years (OR = 2.46; 1.09–5.55); the GSTT1 null genotype and primary anatomical sites of pharynx (OR = 0.37; 0.17–0.79) and larynx (OR = 3.60; 1.93–6.72), can modulate the risk for the disease development. The variables age ≥ 48 years, smoking and drinking can be predictors for head and neck cancer development; moreover, A313G GSTP1 polymorphism, GSTM1 and GSTT1 null genotypes can modulate the risk for this disease.     

Seed and cone morphometric indicators: A new tool for the discrimination between the common Mediterranean pines Pinus halepensis Mill. and P. brutia Ten

Abstract

The two typical Mediterranean pines of Greece (Pinus halepensis Mill. and P. brutia Ten.) show a distinct, natural geographical distribution. However, in sites where they grow in sympatry (mainly due to extended reforestations), their morphological discrimination is not always easy. In the present study, three new morphometric indicators are introduced (at decreasing rank of reliability): (a) seed coat mass fraction, expressed as a percentage of the total seed mass (SM) (overall mean values 27.9 ± 0.5 (n = 160), and 58.0 ± 0.3 (n = 320) from 18 and 16 populations of Aleppo and East Mediterranean pine, respectively), (b) mean SM (16.70 ± 0.26 mg, n = 651, and 42.79 ± 0.61 mg, n = 425 from 18 and 16 populations of each of the two species, respectively) and (c) cone length/width ratio (2.20 ± 0.01, n = 651, and 1.77 ± 0.01, n = 606 from the same 18 and 16 populations, respectively). These three parameters are easily calculated, and constitute a reliable tool for the discrimination of the two pine species on the basis of their reproductive units (cones and seeds), provided that a minimal number of randomly collected samples is used for each indicator: 20 seeds for the measurement of seed coat mass fraction, about 1000 seeds for the estimation of mean SM, and 20 cones for the calculation of the cone length/width ratio. The functional implications of these adaptive traits are discussed.     

Recovery dynamics and viability of the white-tailed eagle (<Emphasis Type="Italic">Haliaeetus albicilla</Emphasis>) in Germany

Understanding the effect of protection measures on recovery of endangered populations is crucial for assessing the efficiency of management plans. Following the ban of DDT, PCB and other detrimental chemicals in the 1970s, the German white-tailed eagle population recovered rapidly. Using nest monitoring data, dead recovery data and population dynamics models, we examined both short and long-term viabilities of the population. Between 1991 and 2005 the proportion of breeding pairs with an active nest among territorial pairs was α = 0.88 ± 0.007. Annual breeding success was γ = 0.62 ± 0.014. Mean fledged brood size was b = 1.50 ± 0.010 fledged/successful breeding pair. The analysis of dead recovery data of 1,273 individuals ringed as nestling between 1991 and 2006 allowed survival rates to be estimated. We needed to distinguish between “young” (5 years old) and “old” (older than 5 years) adults. Furthermore the annual survival rate was higher for juvenile and immature birds (0.921 ± 0.024) than for adults (s _“young” = 0.760 ± 0.097 and s _“old” = 0.875 ± 0.079), a pattern presumably explained by territorial fights. Finally, an age structured model was used to examine the joint effect of population regulation, environmental and demographic stochasticities. All results indicated that only pessimistic scenarios could lead to substantial extinction probabilities within 100 years. We conclude that management measures were successful in removing the main extinction factors of the population and that future conservation efforts need to focus on the remaining ultimate extinction causes.     

Circadian and homeostatic modulation of the attentional blink

An important property of attention is the limitation to process new information after responding to a stimulus. This property of attention can be evaluated by the Attentional Blink (AB), a phenomenon that consists of a failure to detect the second of two targets when the interval between them is 200–500 ms. The aim of the present work is to determine the possible existence of time awake (homeostatic changes) and time of day (circadian rhythm) variations in the AB. Eighteen undergraduate students, 11 men and 7 women, age = 18.06 ± 1.16 years, participated voluntarily in this research. They were recorded in a constant routine protocol during 29 h, in which rectal temperature was recorded every minute, while subjective sleepiness and responses to a Rapid Serial Visual Presentation (RSVP) task, to measure the AB, were recorded every hour. Homeostatic and circadian variations in all parameters of the RSVP task were observed, including changes in the capacity to process a new stimulus (Target 1 accuracy), a second stimulus occurring in a short interval after the first (Target 2 accuracy at lag 2, 200 ms) and to process another successive independent stimulus (Target 2 accuracy at lag 8, 800 ms). The acrophase of these parameters occurred with a phase delay of 2 h compared to the circadian rhythm of rectal temperature. The AB magnitude, an index of the AB, showed a decline with time awake, but no variations with time of day. In conclusion, there are homeostatic and circadian variations in the capacity to process any incoming information, especially in tasks with brief duration stimuli presented at a high frequency.     

A Comparative Study of the Non-acidic Chemically Mediated Antifoulant Properties of Three Sympatric Species of Ascidians Associated with Seagrass Habitats

In this study, the mechanical properties of biofilms formed at the surface of nano-filtration (NF) membranes from a drinking water plant were analysed. Confocal laser scanning microscopy observations revealed that the NF biofilms formed a dense and heterogeneous structure at the membrane surface, with a mean thickness of 32.5 ± 17.7 μm. The biofilms were scraped from the membrane surface and analysed in rotation and oscillation experiments with a RheoStress 150 rotating disk rheometer. During rotation analyses, a viscosity decrease with speed of shearing characteristic of rheofluidification was observed (η = 300 Pa s for ý = 0.3 s^?1). In the oscillation analyses with a sweeping of frequency (1–100 Hz), elasticity (G′) ranged from 3000 to 3500 Pa and viscosity (G″) from 800 to 1200 Pa. Creep curves obtained with an application of a shear stress of 30 Pa were viscoelastic in nature. The G ₀ and η values were, respectively, 1.4 ± 0.3 × 10³ Pa and 3.3 ± 0.65 × 10⁶ Pa s. The relationship between the characteristics of NF biofilms and the flow conditions encountered during NF is discussed.