Chronic sleep reduction in adolescents with Delayed Sleep Phase Disorder and effects of melatonin treatment

Homeostatic and circadian changes that occur during adolescence can result in chronic sleep reduction. This may particularly be true for adolescents with Delayed Sleep Phase Disorder (DSPD), which is associated with late Dim Light Melatonin Onset (DLMO). This study assessed the influence of melatonin treatment on chronic sleep reduction in adolescents with DSPD and examined whether adolescents with DSPD suffer from more chronic sleep reduction than adolescents from the general population before and after melatonin treatment. Adolescents with DSPD (n = 145; 55.9% boys; mean age 15,5 years; mean DLMO = 22:32 h) completed a questionnaire concerning chronic sleep reduction at baseline. From these, 53 adolescents also completed this questionnaire after on average 10 weeks of melatonin treatment. At baseline adolescents with DSPD reported significantly more symptoms of chronic sleep reduction than adolescents from the general population, whereas after treatment they reported significantly less symptoms. DLMO did not influence the effect of treatment. The improvement of chronic sleep reduction after treatment is an important finding, considering the negative consequences of chronic sleep reduction for adolescents' daytime functioning

Screening for sleep reduction in adolescents through self-report: Development and validation of the sleep reduction screening questionnaire (SRSQ)

Background: Sleep reduction, resulting from insufficient or poor sleep, is a common phenomenon in adolescents. Due to its severe negative psychological and behavioral daytime consequences, it is important to have a short reliable and valid measure to assess symptoms of sleep reduction. Objective: This study aims to validate the Sleep Reduction Screening Questionnaire (SRSQ) that can be used to screen for symptoms of sleep reduction in adolescents. Methods: Various samples from the general and clinical populations were included in the study. The SRSQ is a nine-item questionnaire that is based on the longer, four dimensional Chronic Sleep Reduction Questionnaire (Meijer in J Sleep Res 17:395-405, doi:10.1111/j.1365-2869.2008.00677.x, 2008). Items were selected on the basis of principal components analysis, item-total correlations, and substantive consideration. The SRSQ was validated by calculating correlations with self-reported and objective sleep and self-reported daytime functioning. Cut-off scores were determined so that the SRSQ can be used as a screening instrument. Results: Internal consistencies of the SRSQ were good (Cronbach’s alpha = .79 in the general population). Correlations with self-reported sleep, daytime functioning and objective sleep variables were satisfactory and in the expected directions. The SRSQ discriminates well between clinical and non-clinical cases. When accounting for prevalence of sleep reduction symptoms in the general population, the area under the curve was .91, sensitivity was .80 and specificity was .87. Conclusions: The SRSQ appears to be a short reliable and valid questionnaire. Due to the limited number of items and the availability of cut-off scores, it is a practical tool for clinical and research purposes

X(5) critical-point symmetries in 138Gd

The lifetimes of low-lying transitions in138Gd have been measured using the recoil-distance Doppler-shift technique. The resultant reduced transition probabilities have been compared to X(5) critical-point calculations to assess the potential 'phase-transitional' behaviour of138Gd. The X(5) symmetry describes the first order 'phase transition' between sphericity, U(5) and an axially deformed nuclear shape, SU(3). Although a high degree of correspondence is observed between the experimental and theoretical excitation energies, the large uncertainties of the experimental B(E2) values cannot preclude contributions from either vibrational or rotational modes of excitation. In order to further examine the nature of low-lying states in138Gd, ongoing work is aiming to derive solutions to the Bohr Hamiltonian using a more general potential that is not restricted to the X(5) critical point. These results, in parallel to more extensive IBM-1 calculations, will eventually be compared to the experimental results to more accurately locate138Gd along the U(5) - SU(3) arm of the structure triangle

Lifetime measurements in the transitional nucleus 138Gd

Lifetime measurements have been made in the ground-state band of the transitional nucleus 138Gd from coincidence recoil-distance Doppler-shift data. 138Gd nuclei were produced using the 106Cd (36Ar, 2p2n) reaction with a beam energy of 190 MeV. Reduced transition probabilities have been extracted from the lifetime data collected with the Köln plunger placed at the target position of the JUROGAM-II array. The B(E2) values have been compared with predictions from X(5) critical-point calculations, which describe the phase transition between vibrational and axially symmetric nuclear shapes, as well as with IBM-1 calculations at the critical point. While the excitation energies in 138Gd are consistent with X(5) predictions, the large uncertainties associated with the measured B(E2) values cannot preclude vibrational and rotational contributions to the low-lying structure of 138Gd. Although experimental knowledge for the low-lying γ and β-vibrational bands in 138Gd is limited, potential-energy surface calculations suggest an increase in γ softness in the ground-state band. In order to more fully account for the effects of γ softness, the X(5) and IBM-1 calculations need to be extended to include the γ degree of freedom for 138Gd

FISH glossary: an overview of the fluorescence in situ hybridization technique.

The introduction of FISH (fluorescence in situ hybridization) marked the beginning of a new era for the study of chromosome structure and function. As a combined molecular and cytological approach, the major advantage of this visually appealing technique resides in its unique ability to provide an intermediate degree of resolution between DNA analysis and chromosomal investigations while retaining information at the single-cell level. Used to support large-scale mapping and sequencing efforts related to the human genome project, FISH accuracy and versatility were subsequently capitalized on in biological and medical research, providing a wealth of diverse applications and FISH-based diagnostic assays. The diversification of the original FISH protocol into the impressive number of procedures available these days has been promoted throughout the years by a number of interconnected factors: the improvement in sensitivity, specificity and resolution, together with the advances in the fields of fluorescence microscopy and digital imaging, and the growing availability of genomic and bioinformatic resources. By assembling in a glossary format many of the “acronymed” FISH applications published so far, this review intends to celebrate the ability of FISH to re-invent itself and thus remain at the forefront of biomedical research

The effect of residual stress on the Preferential Intergranular Oxidation of Alloy 600

Alloy 600 was exposed to H2-steam to simulate the oxidation that occurs in high temperature water where this alloy is known to be susceptible to SCC. Analytical electron microscopy was employed to characterize the early stages of oxidation to aid in developing an understanding of the stress corrosion cracking behaviour of this alloy. The oxide consisted of sub-surface Cr2O3 particles, preferential intergranular oxidation and formation of surface Ni nodules. The measurements of residual stresses at the microscopic level using a recently-developed FIB micro-hole drilling technique revealed a correlation between local stress variations at the grain boundaries and the oxide morphology.</p