Periodic Variability on Time-scales of Decades to Centuries in Magnetic Ap Stars: Challenges and Strategies

2017 ◽  
Vol 14 (S339) ◽  
pp. 106-109
Author(s):  
G. Mathys
Keyword(s):  
Time Scales ◽  
Current Knowledge ◽  
Main Sequence Stars ◽  
Unique Challenge ◽  
Origin And Evolution ◽  
Rotation Periods ◽  
Orbital Periods ◽  
The One ◽  
Ap Stars ◽  
Incomplete Picture

AbstractRecent studies have revealed the existence of a significant population of Ap stars with extremely long rotation periods, and the frequent occurrence of Ap stars in wide binaries. Those results represent new constraints on the understanding of the origin and evolution of Ap stars, and (by extension) of all upper-main-sequence stars. Current knowledge of Ap stars with the longest rotation and orbital periods remains incomplete, on the one hand because in many cases the periods of interest are longer than the time-spans over which relevant observations have been obtained, and on the other hand because some important subsets of Ap stars have been omitted from the studies that have been carried out until now. Additional observations over time-scales of decades to centuries are needed to complement the current incomplete picture. Securing them with the required accuracy and time coverage, and ensuring that their full exploitation will ultimately be possible, represents a unique challenge in time-domain astronomy.

On The Radii of Ap Stars

1976 ◽  
Vol 32 ◽  
pp. 49-55 ◽  
Author(s):  
F.A. Catalano ◽  
G. Strazzulla
Keyword(s):  
Observational Data ◽  
Line Width ◽  
Main Sequence ◽  
Main Sequence Stars ◽  
Ap Stars

SummaryFrom the analysis of the observational data of about 100 Ap stars, the radii have been computed under the assumption that Ap are main sequence stars. Radii range from 1.4 to 4.9 solar units. These values are all compatible with the Deutsch's period versus line-width relation.

scholarly journals Hepatitis E Virus in Croatia in the “One-Health” Context

Pathogens ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 699
Author(s):  
Anna Mrzljak ◽  
Lorena Jemersic ◽  
Vladimir Savic ◽  
Ivan Balen ◽  
Maja Ilic ◽  
...  
Keyword(s):  
Hepatitis E Virus ◽  
Current Knowledge ◽  
Hepatitis E ◽  
Human Case ◽  
Interspecies Transmission ◽  
Genotype 3 ◽  
Chronic Patients ◽  
Indirect Contact ◽  
The One ◽  
Foodborne Infection

Hepatitis E virus (HEV) is the most common cause of viral hepatitis globally. The first human case of autochthonous HEV infection in Croatia was reported in 2012, with the undefined zoonotic transmission of HEV genotype 3. This narrative review comprehensively addresses the current knowledge on the HEV epidemiology in humans and animals in Croatia. Published studies showed the presence of HEV antibodies in different population groups, such as chronic patients, healthcare professionals, voluntary blood donors and professionally exposed and pregnant women. The highest seroprevalence in humans was found in patients on hemodialysis in a study conducted in 2018 (27.9%). Apart from humans, different studies have confirmed the infection in pigs, wild boars and a mouse, indicating the interspecies transmission of HEV due to direct or indirect contact or as a foodborne infection. Continued periodical surveys in humans and animals are needed to identify the possible changes in the epidemiology of HEV infections.

scholarly journals Helium, [Fe/H] Abundances and the HR (Log TEFF, MBol) Diagram With Hipparcos Data of The Four Nearest Open Clusters: Hyades, Coma Berenices, The Pleiades and Praesepe

1998 ◽  
Vol 11 (1) ◽  
pp. 565-565
Author(s):  
G. Cayrel de Strobel ◽  
R. Cayrel ◽  
Y. Lebreton
Keyword(s):  
Main Sequence ◽  
Open Clusters ◽  
Main Sequence Stars ◽  
Spectroscopic Analyses ◽  
Solar Metallicity ◽  
Metal Abundances ◽  
The Mean ◽  
The Moment ◽  
The One ◽  
Best Fit

After having studied in great detail the observational HR diagram (log Teff, Mbol) composed by 40 main sequence stars of the Hyades (Perryman et al.,1997, A&A., in press), we have tried to apply the same method to the observational main sequences of the three next nearest open clusters: Coma Berenices, the Pleiades, and Praesepe. This method consists in comparing the observational main sequence of the clusters with a grid of theoretical ZAMSs. The stars composing the observational main sequences had to have reliable absolute bolometric magnitudes, coming all from individual Hipparcos parallaxes, precise bolometric corrections, effective temperatures and metal abundances from high resolution detailed spectroscopic analyses. If we assume, following the work by Fernandez et al. (1996, A&A,311,127), that the mixing-lenth parameter is solar, the position of a theoretical ZAMS, in the (log Teff, Mbol) plane, computed with given input physics, only depends on two free parameters: the He content Y by mass, and the metallicity Z by mass. If effective temperature and metallicity of the constituting stars of the 4 clusters are previously known by means of detailed analyses, one can deduce their helium abundances by means of an appropriate grid of theoretical ZAMS’s. The comparison between the empirical (log Teff, Mbol) main sequence of the Hyades and the computed ZAMS corresponding to the observed metallicity Z of the Hyades (Z= 0.0240 ± 0.0085) gives a He abundance for the Hyades, Y= 0.26 ± 0.02. Our interpretation, concerning the observational position of the main sequence of the three nearest clusters after the Hyades, is still under way and appears to be greatly more difficult than for the Hyades. For the moment we can say that: ‒ The 15 dwarfs analysed in detailed in Coma have a solar metallicity: [Fe/H] = -0.05 ± 0.06. However, their observational main sequence fit better with the Hyades ZAMS. ‒ The mean metallicity of 13 Pleiades dwarfs analysed in detail is solar. A metal deficient and He normal ZAMS would fit better. But, a warning for absorption in the Pleiades has to be recalled. ‒ The upper main sequence of Praesepe, (the more distant cluster: 180 pc) composed by 11 stars, analysed in detail, is the one which has the best fit with the Hyades ZAMS. The deduced ‘turnoff age’ of the cluster is slightly higher than that of the Hyades: 0.8 Gyr instead of 0.63 Gyr.

scholarly journals Molecular pathogenetic aspects in the diagnosis of thyroid cancer

1995 ◽  
Vol 41 (6) ◽  
pp. 42-47
Author(s):  
Ye. A. Troshina ◽  
G. A. Gerasimov ◽  
G. F. Alexandrova
Keyword(s):  
Thyroid Cancer ◽  
Nuclear Power ◽  
Current Knowledge ◽  
Malignant Neoplasms ◽  
X Ray ◽  
Tumor Diseases ◽  
Exogenous Factors ◽  
Molecular Aspects ◽  
The One ◽  
Diagnosis Of Thyroid Cancer

Thyroid cancer accounts for 1 - 1.5% of all malignant neoplasms. In recent years, there has been a trend towards an increase in the prevalence of this disease. On the one hand, the frequency of detection of thyroid cancer is associated with the introduction of a number of modern methods of examining patients and the increased oncological alertness of doctors. On the other hand, there is evidence of an increase in the incidence of thyroid cancer associated with an unfavorable environmental situation. An example of this is an increase in the frequency of thyroid damage in people exposed to radiation after the accident at the Chernobyl nuclear power plant. There is evidence that in Japan, thyroid cancer is detected 10 times more often among the population that has undergone nuclear bombing than among other residents of the country. Exogenous risk factors include external x-ray irradiation, previously carried out for medical purposes for various benign and non-tumor diseases of the head and neck. It is believed that exogenous factors are able to more or less affect the thyroid gland and cause a number of molecular changes in it that lead to the development of cancer. The purpose of this review was to summarize the current knowledge of the molecular aspects of thyroid cancer.

scholarly journals Long-term neurodevelopment in children born with esophageal atresia: a systematic review

2021 ◽  
Author(s):  
Camille E van Hoorn ◽  
Chantal A ten Kate ◽  
Andre B Rietman ◽  
Leontien C C Toussaint-Duyster ◽  
Robert Jan Stolker ◽  
...  
Keyword(s):  
Cognitive Development ◽  
Motor Function ◽  
Esophageal Atresia ◽  
Current Knowledge ◽  
Neurodevelopmental Outcome ◽  
Cognitive Outcome ◽  
Term Outcome ◽  
Long Term Outcome ◽  
The One

Summary Background Although the survival rate of esophageal atresia (EA) has increased to over 90%, the risk of functional long-term neurodevelopmental deficits is uncertain. Studies on long-term outcomes of children with EA show conflicting results. Therefore, we provide an overview of the current knowledge on the long-term neurodevelopmental outcome of children with EA. Methods We performed a structured literature search in Embase, Medline Ovid, Web of Science, Cochrane CENTRAL, and Google scholar on November 8, 2020 with the keywords ‘esophageal atresia’, ‘long-term outcome’, ‘motor development’, ‘cognitive development’, and ‘neurodevelopment’. Results The initial search identified 945 studies, of which 15 were included. Five of these published outcomes of multiple tests or tested at multiple ages. Regarding infants, one of six studies found impaired neurodevelopment at 1 year of age. Regarding preschoolers, two of five studies found impaired neurodevelopment; the one study assessing cognitive development found normal cognitive outcome. Both studies on motor function reported impairment. Regarding school-agers, the one study on neurodevelopmental outcome reported impairment. Cognitive impairment was found in two out of four studies, and motor function was impaired in both studies studying motor function. Conclusions Long-term neurodevelopment of children born with EA has been assessed with various instruments, with contrasting results. Impairments were mostly found in motor function, but also in cognitive performance. Generally, the long-term outcome of these children is reason for concern. Structured, multidisciplinary long-term follow-up programs for children born with EA would allow to timely detect neurodevelopmental impairments and to intervene, if necessary.

scholarly journals Two-faced Janus: the dual role of macrophages in atherosclerotic calcification

2021 ◽  
Author(s):  
Olivia J Waring ◽  
Nikolaos T Skenteris ◽  
Erik A L Biessen ◽  
Marjo M P C Donners
Keyword(s):  
Current Knowledge ◽  
Wide Spectrum ◽  
Inflammatory Cells ◽  
Cell Types ◽  
Macrophage Phenotype ◽  
Phenotypic Changes ◽  
Direct Exposure ◽  
Stable Plaque ◽  
Mechanisms Of Development ◽  
The One

Abstract Calcification is an independent predictor of atherosclerosis-related cardiovascular events. Microcalcification is linked to inflamed, unstable lesions, in comparison to the fibrotic stable plaque phenotype generally associated with advanced calcification. This paradox relates to recognition that calcification presents in a wide spectrum of manifestations that differentially impact plaque’s fate. Macrophages, the main inflammatory cells in atherosclerotic plaque, have a multifaceted role in disease progression. They crucially control the mineralization process, from microcalcification to the osteoid metaplasia of bone-like tissue. It is a bilateral interaction that weighs heavily on the overall plaque fate but remains rather unexplored. This review highlights current knowledge about macrophage phenotypic changes in relation to and interaction with the calcifying environment. On the one hand, macrophage-led inflammation kickstarts microcalcification through a multitude of interlinked mechanisms, which in turn stimulates phenotypic changes in vascular cell types to drive microcalcification. Macrophages may also modulate the expression/activity of calcification inhibitors and inducers, or eliminate hydroxyapatite nucleation points. Contrarily, direct exposure of macrophages to an early calcifying milieu impacts macrophage phenotype, with repercussions for plaque progression and/or stability. Macrophages surrounding macrocalcification deposits show a more reparative phenotype, modulating extracellular matrix, and expressing osteoclast genes. This phenotypic shift favours gradual displacement of the pro-inflammatory hubs; the lipid necrotic core, by macrocalcification. Parallels to bone metabolism may explain many of these changes to macrophage phenotype, with advanced calcification able to show homeostatic osteoid metaplasia. As the targeted treatment of vascular calcification developing in atherosclerosis is thus far severely lacking, it is crucial to better understand its mechanisms of development.

scholarly journals Right Ventricle Remodeling and Function in Scleroderma Patients

2018 ◽  
Vol 2018 ◽  
pp. 1-9
Author(s):  
Roxana Cucuruzac ◽  
Iolanda Muntean ◽  
Imre Benedek ◽  
Andras Mester ◽  
Nora Rat ◽  
...  
Keyword(s):  
Current Knowledge ◽  
Severe Disease ◽  
Mortality Rates ◽  
Pulmonary Artery Hypertension ◽  
Organ Manifestations ◽  
Therapeutic Measures ◽  
The One ◽  
And Function ◽  
Adaptive Pattern ◽  
Functional Alteration

Scleroderma, known also as systemic sclerosis (SSc), is a severe disease associated with high mortality rates, and right ventricular (RV) remodeling and dysfunction, along with pulmonary artery hypertension (PAH), are among the most important internal organ manifestations of this disease. PAH has a higher prevalence in patients with SSc compared to the general population and represents a significant predictor of mortality in SSc. In patients with SSc, the morphological remodeling and alteration of RV function begin even before the setting of PAH and lead to development of a specific adaptive pattern of the RV which is different from the one recorded in patients with IAPH. These alterations cause worse outcomes and increased mortality rates in SSc patients. Early detection of RV dysfunction and remodeling is possible using modern imaging tools currently available and can indicate the initiation of specific therapeutic measures before installation of PAH. The aim of this review is to summarize the current knowledge related to mechanisms involved in the remodeling and functional alteration of the RV in SSc patients.

scholarly journals Optical variability of three extreme TeV blazars

2020 ◽  
Vol 496 (2) ◽  
pp. 1430-1444
Author(s):  
Ashwani Pandey ◽  
Alok C Gupta ◽  
G Damljanovic ◽  
P J Wiita ◽  
O Vince ◽  
...  
Keyword(s):  
Time Scales ◽  
Spectral Energy ◽  
Spectral Variability ◽  
Weighted Mean ◽  
Energy Distributions ◽  
Optical Telescope ◽  
Physical Mechanisms ◽  
Photometric Observations ◽  
All Optical ◽  
The One

ABSTRACT We present the results of optical photometric observations of three extreme TeV blazars, 1ES 0229+200, 1ES 0414+009, and 1ES 2344+514, taken with two telescopes (1.3 m Devasthal Fast Optical Telescope, and 1.04 m Sampuranand Telescope) in India and two (1.4 m Milanković telescope and 60 cm Nedeljković telescope) in Serbia during 2013–2019. We investigated their flux and spectral variability on diverse time-scales. We examined a total of 36 intraday R-band light curves of these blazars for flux variations using the power-enhanced F-test and the nested ANOVA test. No significant intraday variation was detected on 35 nights, and during the one positive detection the amplitude of variability was only 2.26 per cent. On yearly time-scales, all three blazars showed clear flux variations in all optical wavebands. The weighted mean optical spectral index (αBR), calculated using B − R colour indices, for 1ES 0229+200 was 2.09 ± 0.01. We also estimated the weighted mean optical spectral indices of 0.67 ± 0.01 and 1.37 ± 0.01 for 1ES 0414+009, and 1ES 2344+514, respectively, by fitting a single power law (Fν ∝ ν−α) in their optical (VRI) spectral energy distributions. A bluer-when-brighter trend was only detected in the blazar 1ES 0414+009. We briefly discuss different possible physical mechanisms responsible for the observed flux and spectral changes in these blazars on diverse time-scales.

scholarly journals VEGF-A in Cardiomyocytes and Heart Diseases

2020 ◽  
Vol 21 (15) ◽  
pp. 5294
Author(s):  
Mariantonia Braile ◽  
Simone Marcella ◽  
Leonardo Cristinziano ◽  
Maria Rosaria Galdiero ◽  
Luca Modestino ◽  
...  
Keyword(s):  
Current Knowledge ◽  
Heart Diseases ◽  
Premature Death ◽  
Vascular Endothelial ◽  
Main Cell Type ◽  
High Concentrations ◽  
Cytokine Stimulation ◽  
The One ◽  
Endothelial Growth Factor

The vascular endothelial growth factor (VEGF), a homodimeric vasoactive glycoprotein, is the key mediator of angiogenesis. Angiogenesis, the formation of new blood vessels, is responsible for a wide variety of physio/pathological processes, including cardiovascular diseases (CVD). Cardiomyocytes (CM), the main cell type present in the heart, are the source and target of VEGF-A and express its receptors, VEGFR1 and VEGFR2, on their cell surface. The relationship between VEGF-A and the heart is double-sided. On the one hand, VEGF-A activates CM, inducing morphogenesis, contractility and wound healing. On the other hand, VEGF-A is produced by CM during inflammation, mechanical stress and cytokine stimulation. Moreover, high concentrations of VEGF-A have been found in patients affected by different CVD, and are often correlated with an unfavorable prognosis and disease severity. In this review, we summarized the current knowledge about the expression and effects of VEGF-A on CM and the role of VEGF-A in CVD, which are the most important cause of disability and premature death worldwide. Based on clinical studies on angiogenesis therapy conducted to date, it is possible to think that the control of angiogenesis and VEGF-A can lead to better quality and span of life of patients with heart disease.

scholarly journals The Evolutionary Status of the Secondaries of Cataclysmic Binaries

1983 ◽  
Vol 72 ◽  
pp. 257-262
Author(s):  
H. Ritter
Keyword(s):  
Probability Distribution ◽  
Main Sequence ◽  
The Other ◽  
Initial Mass ◽  
Evolutionary Status ◽  
Mass Ratio ◽  
Main Sequence Stars ◽  
Cataclysmic Binaries ◽  
Low Mass ◽  
Orbital Periods

ABSTRACTIt is shown that the secondary components of cataclysmic binaries with orbital periods of less than ~10 hours are indistinguishable from ordinary low-mass main-sequence stars and that, therefore, they are essentially unevolved. On the other hand, it is shown that, depending on the mass ratio of the progenitor system, the secondary of a cataclysmic binary could be significantly evolved. The fact that nevertheless most of the observed secondaries are essentially unevolved can be accounted for by assuming that the probability distribution for the initial mass ratio is not strongly peaked towards unity mass ratio.

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