Thermal infrared spectra of Saturn from 10–1400 cm
−1 at 15 cm
−1 spectral resolution and a spatial resolution of 1°–2° latitude have been obtained by the Cassini Composite Infrared Spectrometer ...Flasar, F.M., and 44 colleagues, 2004. Space Sci. Rev. 115, 169–297. Many thousands of spectra, acquired over eighteen-months of observations, are analysed using an optimal estimation retrieval code Irwin, P.G.J., Parrish, P., Fouchet, T., Calcutt, S.B., Taylor, F.W., Simon-Miller, A.A., Nixon, C.A., 2004. Icarus 172, 37–49 to retrieve the temperature structure and
para-hydrogen distribution over Saturn's northern (winter) and southern (summer) hemispheres. The vertical temperature structure is analysed in detail to study seasonal asymmetries in the tropopause height (65–90 mbar), the location of the radiative–convective boundary (350–500 mbar), and the variation with latitude of a temperature knee (between 150 and 300 mbar) which was first observed in inversions of Voyager/IRIS spectra Hanel, R., and 15 colleagues, 1981. Science 212, 192–200; Hanel, R., Conrath, B., Flasar, F.M., Kunde, V., Maguire, W., Pearl, J.C., Pirraglia, J., Samuelson, R., Cruikshank, D.P., Gautier, D., Gierasch, P.J., Horn, L., Ponnamperuma, C., 1982. Science 215, 544–548. Uncertainties due to both the modelling of spectral absorptions (collision-induced absorption coefficients, tropospheric hazes, helium abundance) and the nature of our retrieval algorithm are quantified.
Temperatures in the stratosphere near 1 mbar show a 25–30 K temperature difference between the north pole and south pole. This asymmetry becomes less pronounced with depth as the radiative time constant for the atmospheric response increases at deeper pressure levels. Hemispherically-symmetric small-scale temperature structures associated with zonal winds are superimposed onto the temperature asymmetry for pressures greater than 100 mbar. The
para-hydrogen fraction in the 100–400 mbar range is greater than equilibrium predictions for the southern hemisphere and parts of the northern hemisphere, and less than equilibrium predictions polewards of 40° N.
The temperature knee between 150–300 mbar is larger in the summer hemisphere than in the winter, smaller and higher at the equator, deeper and larger in the equatorial belts and small at the poles. Solar heating on tropospheric haze is proposed as a possible mechanism for this effect; the increased efficiency of
ortho- to
para-hydrogen conversion in the southern hemisphere is consistent with the presence of larger aerosols in the summer hemisphere, which we demonstrate to be qualitatively consistent with previous studies of Saturn's tropospheric aerosol distribution.
Stratospheric temperatures on Saturn imply a strong decay of the equatorial winds with altitude. If the decrease in winds reported from recent Hubble Space Telescope images is not a temporal change, ...then the features tracked must have been at least 130 kilometers higher than in earlier studies. Saturn's south polar stratosphere is warmer than predicted from simple radiative models. The C/H ratio on Saturn is seven times solar, twice Jupiter's. Saturn's ring temperatures have radial variations down to the smallest scale resolved (100 kilometers). Diurnal surface temperature variations on Phoebe suggest a more porous regolith than on the jovian satellites.
The Delphi technique Bowles, N
Nursing standard,
1999 Jul 28-Aug 3, Letnik:
13, Številka:
45
Journal Article
Recenzirano
The Delphi survey technique has merit in both qualitative and quantitative research, but fewer researchers are using it. This article reviews the Delphi technique and its use in nursing, medical and ...allied health literature between 1981 and 1998. The strengths and weaknesses of the technique are discussed.
Abstract
Introduction
Cannabis use is on the rise in the US, and while the cannabis plant and related compounds are considered to have low toxicity, the impact on physiology including sleep remains ...unclear. Further, the bulk of cannabis research has focused on adolescents and young adults despite growing use among the elderly. Thus, this analysis sought to determine the impact of the frequency of cannabis use on sleep duration and determine if this relationship varies by age.
Methods
This cross-sectional study used data from the 2016-2018 Behavioral Risk Factor Surveillance System surveys. Multinomial logistic regression was used to evaluate the association between the frequency of cannabis use, 0-30 times over the prior 30 days; and average sleep duration, short (<7 hours); recommended (7-9 hours); and long (>9 hours) sleep.
Results
The study sample included 235,667 participants (48% male, 43% 18-44 years old and 35% 44-64 years old) of which 14,122 consumed cannabis. The weighted proportion who reported using cannabis 1-4x, 5-15x, or more than 16x/month were 3.1% (95% CI, 3.0%-3.3%), 2.1% (2.0%-2.2%), and 4.4% (4.2%-4.6%) respectively. In an age stratified model adjusted for sociodemographic and clinical characteristics, there were no associations between sleep and cannabis use up to 15x/month. Among those adults who consumed cannabis more than 16x/month: (1) 18-44 year olds were more likely to report either short sleep (risk ratio (RR), 1.21; 95% CI, 1.05-1.39) or long sleep (RR, 1.57; 95% CI, 1.11-2.22) as opposed to the recommended amount of sleep; whereas (2) 44-64 year olds demonstrated an increased risk for long sleep (RR, 1.77; 95% CI, 1.09-2.89); and (3) participants 65 years and older demonstrated an increased risk for short sleep (RR, 1.61; 95% CI, 1.04-2.49).
Conclusion
We demonstrate that modest cannabis use was not associated with sleep, whereas daily cannabis use is associated with age-dependent sleep duration above and below the recommended amount.
Support
KL2TR002370, 2R25HL105444-09.
Abstract
Introduction:
Circadian misalignment (e.g., shift work) is associated with worsened mood and mood has been shown to have a circadian rhythm. Notably, rhythmicity has been shown for feelings ...associated with reward-related motivation (positive affect) but not threat-related motivation (negative affect). We tested whether or not there exists a circadian rhythm in mood as assessed by the complete Positive and Negative Affect Scales (PANAS) and a questionnaire with validity in both psychiatric and normative populations.
Methods:
15 participants without chronic medical or psychiatric illnesses were studied (aged 41–63 years; 9 females). Following 1–3 weeks of a regular sleep/wake schedule participants underwent a laboratory forced desynchrony protocol that distributed all scheduled sleep/wake behaviors evenly across the circadian cycle (achieved by scheduling 10 identical, recurrent 5 h 20 min ‘days’ in dim light thereby desynchronizing the circadian and behavioral cycles). POMS-B and PANAS were completed ~30 min. after waking. Scores were converted to z-scores and analyzed by cosinor analysis. Circadian phase at each mood assessment was determined relative to the salivary dim light melatonin onset (DLMO, 3 pg/ml threshold).
Results:
Both POMS-B mood score and PANAS positive affect items exhibited robust circadian rhythms (both p <0.001) with the worst mood and lowest positive affect occurring during the biological night (~6 hours after the DLMO or ~2:45 am) and the best mood and greatest positive affect at the end of the biological day (~2 hours before the DLMO). Negative affect mirrored positive affect (p = 0.01) with a peak ~ 6 hours after the DLMO and minimum ~6 hours before the DLMO but with an amplitude that was 39% of the rhythm in positive affect.
Conclusion:
Mood has an endogenous circadian rhythm driven principally by positive affect but also influenced by negative affect. Normative and clinical assessments of mood should take these rhythms into account. These rhythms may underlie the association between circadian misalignment and mood disorders and differences in rhythmicity of positive and negative affect might contribute to mood disorder risk.
Support (If Any):
R01 HL125893 (to SAS), NCC 9–58 and F32HL131308 (to SST) and UL1TR000128 (to Oregon Clinical & Translational Research Institute).
Abstract
Introduction:
Appetite is affected by the size and time since a prior meal, the overnight fast, and possibly sleep itself. Additionally, there exists an endogenous circadian rhythm in ...appetite with a trough during the biological morning independent of calories consumed, time since prior meal, and time since waking. How these factors interact is unknown. Thus, we assessed how sleep and fasting affect appetite across the circadian cycle.
Methods:
Eight healthy participants (mean age, 51 years; mean BMI, 25.3 kg/m2; 4 females) underwent a laboratory protocol that balanced eucaloric meals and sleep periods evenly across the circadian cycle (by scheduling 10 identical, recurrent 5h 20min ‘days’ in dim light thereby desynchronizing the circadian and behavioral cycles). Participants ate one identical meal each wake period and rated hunger immediately prior to sleep (30 minutes after each meal), and at the end of each sleep opportunity. Sleep was assessed with polysomnography. Salivary melatonin was used to assess circadian phase (phase marker = dim light melatonin onset DLMO).
Results:
Appetite increased across each sleep opportunity with a median increase of 32%. This increase was dependent upon circadian phase (p=0.009), with the greatest increase in hunger when participants awoke in the biological afternoon (~6hrs before DLMO; ~2:45 pm). The lowest increase in hunger across the sleep period occurred during the biological night (~2hrs after DLMO; ~10:45 pm). Group mean peak to trough difference was 8 % of the full range of the hunger scale. This circadian variation in increase in appetite across sleep was correlated with the number of arousals from sleep (p=0.038), but was not significantly associated with sleep efficiency.
Conclusion:
The increase in appetite across a sleep and fasting period is modulated by the circadian system, with the greatest increase when sleep occurs across the biological morning and into the afternoon. The mechanism may be related to sleep quality (number of arousals). Such results may have considerable relevance to energy balance and diet planning in people with disturbed sleep, and night shift workers who have both disturbed sleep and misalignment between meal timing and circadian phase.
Support (If Any):
R01 HL125893 (to SAS).
Abstract
Introduction:
Double product (DP), the product of heart rate and systolic pressure, is a non-invasive index of myocardial oxygen consumption commonly used for cardiovascular (CV) risk ...stratification. In the general population, DP peaks in the afternoon, but whether the endogenous circadian system contributes to the day/night pattern is unknown. We tested whether there exists an endogenous circadian rhythm in DP in healthy individuals, and whether this rhythm is different between non-obese and obese healthy individuals who may be considered to have greater cardiovascular vulnerability.
Methods:
15 healthy participants were studied (aged 41–63 years; 4 obese (BMI>30 kg/m2); 9 women, 1 with mild hypertension). Following 1–3 weeks of regular sleep/wake schedules at home, participants underwent a 5 day in-lab forced desynchrony protocol (achieved by scheduling 10 identical, recurrent 5 h 20 min ‘days’ in dim light, thereby desynchronizing the circadian and behavioral cycles). Heart rate and blood pressure were measured while at rest at the beginning of each wake period, and DP was calculated. Circadian phase at each measurement was determined relative to the dim light melatonin onset, defined by salivary melatonin >3pg/mL. Cosinor analyses were performed on DP and the interaction between BMI and circadian phase was tested.
Results:
Across all subjects DP at rest exhibited a significant endogenous circadian rhythm in our sample (p<0.05) with a trough at ~4AM and peak at ~7PM. Resting DP was greater in obese individuals and there was a significant BMI by phase interaction (p=0.04) such that the obese group had a peak ~4 hours later than the non-obese group.
Conclusion:
DP at rest has a strong endogenous circadian rhythm in healthy individuals with differences between non-obese and obese participants. These differences may partly explain the increased cardiovascular risk that accompanies obesity. Our results also suggest that the administration of medications to lower DP might need to be timed, and titrated differently in non-obese versus obese individuals.
Support (If Any):
R01 HL125893 (to SAS) and UL1TR000128 (to OHSU Oregon Clinical & Translational Research Institute), National Space Biomedical Research Institute through NCC 9–58 and F32HL131308 (to SST).
Aims This is a comparative study of the leadership provided by nurse managers and leaders in Nursing Development Units and conventional clinical settings in England.
Background Nursing development ...units (NDUs) were originally conceived as centres of nursing excellence, innovation and leadership development. This article describes the first published use of a leadership practices inventory (LPI) explicitly based upon a model of transformational leadership. This style of leadership has been commended as highly effective and suitable for nursing.
Methods The use of the LPI was piloted as a postal questionnaire and as a schedule for telephone interviewing, these pilots supported the use of telephone interviewing in the main study. Two matched samples of 70 nurses in total were recruited from across England, comprising 14 nurse leaders and 56 of their day to day colleagues. Data was collected by telephone interviewing over a 6‐week period between February and April 1998. Six null hypotheses were developed to identify significant inter‐group differences in leadership behaviour. Descriptive and inferential data analysis techniques were employed using SPSS for Windows.
Findings The leadership provided by NDU leaders was evaluated more highly than non‐NDU leaders. A higher level of congruence between self and observer evaluations was shown by NDU leaders. Statistically significant inter‐group differences were apparent in three of the five practices of exemplary leadership and in the overall leadership behaviour. NDU leaders show greater self awareness and are more transformational than their non‐NDU counterparts. The limitations of the study design are discussed.
Conclusions NDU leaders provide leadership of a more transformational nature than their counterparts working in conventional settings. This finding suggests that NDU leaders have enhanced leadership potential and that formalizing nursing development within NDUs may promote the emergence of transformational leadership and provide a microculture in which it might flourish. The LPI is regarded as a useful, adaptable tool suitable for use in UK nursing applications including research, leadership development and education.
Isolated left ventricular noncompaction (LVNC) is a form of cardiomyopathy that most commonly presents in infancy with a hypertrophic and dilated left ventricle characterized by deep trabeculations ...and intertrabecular recesses. Our goal was to determine the frequency of mutations in
G4.5, α-
dystrobrevin, and
FK Binding protein-12 in isolated LVNC patients. No mutations were identified in 47 of the 48 patients studied, while a splice site acceptor site mutation of intron 10 of
G4.5 was identified in one patient, resulting in the deletion of exon 10 from the mRNA.
The genetic basis of a number of inherited cardiovascular diseases has been elucidated over the last few years, including the long QT syndromes, hypertrophic cardiomyopathy and dilated ...cardiomyopathy. While genetic heterogeneity has been demonstrated in most of these diseases, a pattern has emerged, specifically that genes encoding proteins with similar functions or involved in the same pathway are responsible for a particular disease or syndrome. Based on this observation we proposed the "final common pathway" hypothesis. In the case of the arrhythmogenic disorders, the long QT syndromes and Brugada syndrome, mutations have been described in a number of ion channel proteins, including cardiac potassium (KVLQT1, HERG and minK) and sodium (SCN5A) channels. Thus, using the "final common pathway" hypothesis we have proposed these diseases to be "ion channelopathies". Hypertrophic cardiomyopathy appears to be a disease of the sarcomere ("sarcomyopathy") since all the disease-causing mutations have been identified in the gene encoding many of the sarcomeric proteins, including beta-myosin heavy chain, alpha-tropomyosin, troponin I and troponin T, as well as in actin, close to the beta-myosin heavy chain binding site. The genes responsible for familial dilated cardiomyopathy have been less well characterized. For X-linked dilated cardiomyopathy, mutations in the dystrophin and G4.5 genes have been reported. In addition, mutations in actin (close to the dystrophin binding domain) and desmin, a component of the intermediate filaments, have been reported. However, the genes at a further 6 loci associated with autosomal dominant dilated cardiomyopathy (associated with conduction disease in 2 cases) remain unidentified. Due to the mutations in dystrophin, actin and desmin, we have proposed that dilated cardiomyopathy is a "cytoskeletalopathy", and we are currently investigating the involvement of these genes in patients.
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