PURPOSE. The article looks at self-esteem and depression during adolescence. It is a theoretical study of the relationship between depression and self-esteem. There are types of self-esteem, ...self-esteem by gender and age. The theories of depression in adolescence, as well as the factors leading to depression, are examined. Several scales for assessing depression are presented. In view of the application of the main features of self-esteem and depression, their intersections in practical context are examined.
In an effort to locate the sites of emission at different frequencies and physical processes causing variability in blazar jets, we have obtained high time-resolution observations of BL Lacertae over ...a wide wavelength range: with the Transiting Exoplanet Survey Satellite (TESS) at 6000-10000 with 2 minute cadence; with the Neil Gehrels Swift satellite at optical, UV, and X-ray bands; with the Nuclear Spectroscopic Telescope Array at hard X-ray bands; with the Fermi Large Area Telescope at γ-ray energies; and with the Whole Earth Blazar Telescope for measurement of the optical flux density and polarization. All light curves are correlated, with similar structure on timescales from hours to days. The shortest timescale of variability at optical frequencies observed with TESS is ∼0.5 hr. The most common timescale is 13 1 hr, comparable with the minimum timescale of X-ray variability, 14.5 hr. The multiwavelength variability properties cannot be explained by a change solely in the Doppler factor of the emitting plasma. The polarization behavior implies that there are both ordered and turbulent components to the magnetic field in the jet. Correlation analysis indicates that the X-ray variations lag behind the γ-ray and optical light curves by up to ∼0.4 day. The timescales of variability, cross-frequency lags, and polarization properties can be explained by turbulent plasma that is energized by a shock in the jet and subsequently loses energy to synchrotron and inverse Compton radiation in a magnetic field of strength ∼3 G.
ABSTRACT
We report here the first results from a 15-yr long variability monitoring of the z = 2.0 quasar QSO B1312+7837. It shows luminosity changes with a period P ∼ 6.13 yr (P ∼ 2.04 yr at rest ...frame) and amplitude of ∼0.2 mag, superimposed on a gradual dimming at a rate of ∼0.55 mag per 100 yr. Two false periods associated with power peaks in the data windowing function were discarded. The measured period is confirmed with a bootstrapping Monte Carlo simulation. A damped random walk model yields a better fit to the data than a sine-function model, but at the cost of employing some high-frequency variations which are typically not seen in quasars. We consider the possible mechanisms driving this variability, and conclude that orbital motion of two supermassive black holes – result from a recent galaxy merger – is a possible explanation.
Context. The BL Lac object 3C 371 was observed by the Transiting Exoplanet Survey Satellite (TESS) for approximately a year, between July 2019 and July 2020, with an unmatched two-minute imaging ...cadence. In parallel, the Whole Earth Blazar Telescope (WEBT) Collaboration organized an extensive observing campaign, providing three years of continuous optical monitoring between 2018 and 2020. These datasets allow for a thorough investigation of the variability of the source. Aims. The goal of this study is to evaluate the optical variability of 3C 371. Taking advantage of the remarkable cadence of TESS data, we aim to characterize the intra-day variability (IDV) displayed by the source and identify its shortest variability timescale. With this estimate, constraints on the size of the emitting region and black hole mass can be calculated. Moreover, WEBT data are used to investigate long-term variability (LTV), including in terms of the spectral behavior of the source and the polarization variability. Based on the derived characteristics, we aim to extract information on the origin of the variability on different timescales. Methods. We evaluated the variability of 3C 371 by applying the variability amplitude tool, which quantifies variability of the emission. Moreover, we employed common tools, such as ANOVA (ANalysis Of VAariance) tests, wavelet and power spectral density (PSD) analyses to characterize the shortest variability timescales present in the emission and the underlying noise affecting the data. We evaluated the short- and long-term color behavior to understand its spectral behavior. The polarized emission was analyzed, studying its variability and possible rotation patterns of the electric vector position angle (EVPA). Flux distributions of the IDV and LTV were also studied with the aim being to link the flux variations to turbulent and/or accretion-disk-related processes. Results. Our ANOVA and wavelet analyses reveal several entangled variability timescales. We observe a clear increase in the variability amplitude with increasing width of the time intervals evaluated. We are also able to resolve significant variations on timescales of as little as ∼0.5 h. The PSD analysis reveals a red-noise spectrum with a break at IDV timescales. The spectral analysis shows a mild bluer-when-brighter (BWB) trend on long timescales. On short timescales, mixed BWB, achromatic and redder-when-brighter signatures can be observed. The polarized emission shows an interesting slow EVPA rotation during the flaring period, where a simple stochastic model can be excluded as the origin with a 3 σ significance. The flux distributions show a preference for a Gaussian model for the IDV, and suggest it may be linked to turbulent processes, while the LTV is better represented by a log-normal distribution and may have a disk-related origin.
Assessment of cancer related fatigue Strebkova, R.; Petkova, M.; Minev, M.
Trakia journal of sciences,
09/2017, Volume:
15, Issue:
3
Journal Article
Peer reviewed
Open access
Cancer-related fatigue is one of the most common and significant symptoms experienced by cancer patients. The cancer-related fatigue can occur at any stage of the disease or its treatment and has an ...impact on patient's quality of life, regarding physical functioning and the ability to perform activities of daily living. In addition, it is associated with psychological distress. There is no agreement between various authors about the definition and measurement of cancer-related fatigue. There is a range of scales which measure cancer-related fatigue based on unidimensional or multi-dimensional perspective. This review aims to identify available tools applied in practice for the measurement and evaluation of cancer-related fatigue and discusses important conceptual and psychometric characteristics of these instruments.
PURPOSE. The aim of this study is to discuss personal and demographic factors that influence the relationship between physical activity and awareness of one's own body, as well as the pain response ...(threshold and tolerance of pain), situational anxiety and personality. In the study 38 healthy individual- volunteers, students in Trakia University - Stara Zagora were selected. All participants were divided into two groups: actively involved in individual or team sport (n = 19) and healthy normaly active subjects (non-athletes, n = 19). The age of the study participants ranged between 18 and 39 years, while the gender breakdown was as follows: men - 22 women – 16. Methods: Psychological Questionnaires: Body Awareness Questionnaire that asks subjects to rate, on a 4 point scale, the degree to which they were currently experiencing symptoms of sympathetic arousal, State Trait Anger Scale, and State Trait Anxiety Scale. Objective methods (cold pressure test) are used only to determine the pain sensation and pain tolerance thresholds. The results of investigation support significant differences between athletes and non-athletes in pain thershold, body awareness and anxiety. The study conclusions discuss body awareness as an increasing factor for pain resistance in athletes and as an integral part of the learning process among them.
Self-esteem in adolescents Minev, M.; Petrova, B.; Mineva, K. ...
Trakia journal of sciences,
06/2018, Volume:
16, Issue:
2
Journal Article
Peer reviewed
Open access
PURPOSE. Self-esteem is an overall evaluation of the person’s value, expressed in a positive or negative orientation towards himself. Its development starts from birth and is constantly changing ...under the influence of experience (1). Especially important is the role of self-esteem in the process of adolescence. During this period, it correlates with both academic achievement and mental health. The aim of this study is to analyze the correlation between academic achievement and self-esteem among teenagers. Forty 14-year-old students (20 boys and 20 girls) with excellent, very good and good results in school were examined. Methods: Self-Esteem Scale (RSE) (2). The study results show that girls have significantly more negative attitudes towards themselves (x = 32.25) comparing with boys (x = 25.14). These results support the need for further research to explore how individual and contextual factors affect the development of self-esteem over the school years.
Pain is an experience that has physical, psychological and social aspects. Sensitivity to pain is individual and depends on psychological factors. Studies have shown that anxiety is associated with ...the perception of experimentally induced pain. PURPOSE: The purpose of the present study is to examine the relationship between anxiety, threshold and tolerance to experimentally induced pain in healthy persons. METHODS: 35 healthy persons at the age from 19 to 39, 20 women and 15 men were examined. Methods: Spielberger’s questionnaire, Cold pressor test, Visual Analog Scale for Pain, Descriptive statistics, Correlation analysis, Mann-Whitney’s Test. RESULTS: Significant differences in tolerance to pain were identified depending on the levels of state anxiety (U=12.5, Р=0.037). The state anxiety was greatly related to the intensity of the pain experienced. (Spearman rho=0.49, P=0.008). Significant differences were not found in threshold, tolerance and intensity of pain depending on the levels of trait anxiety in the examined people. CONCLUSIONS: The increased levels of state anxiety in healthy persons exposed to experimentally induced pain suggest a weaker endurance to pain and perceiving it as stronger.
Laser milling: Pulse duration effects on surface integrity Petkov, P V; Dimov, S S; Minev, R M ...
Proceedings of the Institution of Mechanical Engineers. Part B, Journal of engineering manufacture,
01/2008, Volume:
222, Issue:
1
Journal Article, Conference Proceeding
Peer reviewed
Open access
Laser milling of engineering materials is a viable alternative to conventional methods for machining complex microcomponents. The laser source employed to perform such microstructuring has a direct ...impact on achievable surface integrity. At the same time, the trade-offs between high removal rates and the resulting surface integrity should be taken into account when selecting the most appropriate ablation regime for performing laser milling. In this paper the effects of pulse duration on surface quality and material microstructure are investigated when ablating a material commonly used for manufacturing microtooling inserts. For both micro- and nanosecond laser regimes, it was estimated that the heat-affected zone on the processed surface is within 50 μm. When performing ultra-short pulsed laser ablation, the effects of heat transfer are not as evident as they are after processing with longer laser pulse durations. Although some heat is dissipated into the bulk when working in pico- and femtosecond regimes it is not sufficient to trigger significant structural changes.
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