15 research outputs found
Numerical Study of the Electron Lateral Distribution in Atmospheric Showers of High Energy Cosmic Rays
No full textAbstract: The study of the lateral distribution of electrons in an atmospheric cascade can lead to useful conclusions on the mass and energy of the primary cosmic particle. In this work we compare the results we get from simulations by the CORSIKA program, with the theoretical NKG function expressing the lateral distribution of electrons. We then modify the original NKG function to fit better the data of the simulation. Finally, we propose this procedure as a method to approach the mass of the primary particle which started the atmospheric cascade
A CONTRIBUTION TO THE STUDY OF POSITION ANNIHILATION IN AMORPHOUS METALLIC ALLOYS
No full textTHE POSITRON ANNIHILATION IN TRANSITION METAL-METALLOID AMORPHOUS ALLOYS HAS BEEN STUDIED. THE TEMPERATURE DEPENDENCE OF POSITRON ANNIHILATION (BETWEEN 12K AND 293K) WAS EXPLAINED BY ACCEPTING THE EXISTENCE OF A VARIETY OF STRUCTURAL "DEFECTS" WHICH RESULTS TO POSITRON TRAPPING. THE POSITRON BINDING ENERGY IN SHALLOW TRAPS WAS FOUND NOT EXCEEDING 0.1 EV. STRUCTURAL RELAXATION WAS OBSERVED TO RESULT TO A DECREASE OF THE FREE VOLUME, NOT AFFECTING SUBSTANTIALLY SHALLOW TRAPS. THESE TRAPS SEEMS TO BE A KIND OF LINEAR DEFECTS. RECRYSTALLIZATION OF AMORPHOUS ALLOYS (BY RELATIVELY HIGH TEMPERATURE ANNEALING) AFFECTS SIGNIFICANTLY POSITRON ANNIHILATION CHARACTERISTICS. THE MAIN FEATURES ARE: A) A MONOTONOUS DECREASE IN POSITRON LIFETIME AND S-PARAMETER DURING THE GROWTH OF SINGLE PHASE CRYSTALLINE GRAINS AND B) THE EXISTENCE OF A MINIMUM DUE TO RECRYSTALLIZATION OF METASTABLE CRYSTALLINE PHASES WHICH HAVE APPEARED AT THE FIRST STAGES OF CRYSTALLIZATION.ΜΕΛΕΤΗΘΗΚΕ Η ΕΞΑΥΛΩΣΗ ΠΟΖΙΤΡΟΝΙΩΝ ΣΕ ΑΜΟΡΦΑ ΜΕΤΑΛΛΙΚΑ ΚΡΑΜΑΤΑ ΜΕΤΑΒΑΤΙΚΟΥ ΜΕΤΑΛΛΟΥ-ΜΕΤΑΛΛΟΕΙΔΩΝ. Η ΕΞΑΡΤΗΣΗ ΤΗΣ ΕΞΑΥΛΩΣΗΣ ΑΠΟ ΤΗ ΘΕΡΜΟΚΡΑΣΙΑ (ΜΕΤΑΞΥ 12Κ ΚΑΙ 293K) ΕΡΜΗΝΕΥΤΗΚΕ ΜΕ ΤΗΝ ΥΠΑΡΞΗ ΜΙΑΣ ΠΟΙΚΙΛΙΑΣ "ΑΤΕΛΕΙΩΝ" ΔΟΜΗΣ ΠΟΥ ΠΡΟΚΑΛΟΥΝ ΠΑΓΙΔΕΥΣΗ ΤΩΝ ΠΟΖΙΤΡΟΝΙΩΝ. Η ΕΝΕΡΓΕΙΑ ΣΥΝΔΕΣΗΣ ΣΤΙΣ ΡΗΧΕΣ ΠΑΓΙΔΕΣ ΒΡΕΘΗΚΕ ΜΙΚΡΟΤΕΡΗ ΤΟΥ 0,1 EV. Η ΔΟΜΙΚΗ ΧΑΛΑΡΩΣΗ ΠΡΟΚΑΛΕΙ ΚΥΡΙΩΣ ΜΕΙΩΣΗ ΤΟΥ ΕΛΕΥΘΕΡΟΥ ΟΓΚΟΥ, ΧΩΡΙΣ ΕΠΗΡΕΑΣΜΟ ΤΩΝ ΡΗΧΩΝ ΠΑΓΙΔΩΝ. ΟΙ ΤΕΛΕΥΤΑΙΕΣ ΦΑΙΝΕΤΑΙ ΟΤΙ ΑΠΟΤΕΛΟΥΝ ΚΑΠΟΙΟ ΕΙΔΟΣ ΓΡΑΜΜΙΚΩΝ ΑΤΕΛΕΙΩΝ . Η ΑΝΑΚΡΥΣΤΑΛΛΩΣΗ ΤΩΝ ΑΜΟΡΦΩΝ ΚΡΑΜΑΤΩΝ (ΠΟΥ ΠΡΟΚΑΛΕΙΤΑΙΜΕ ΑΝΑΠΤΗΣΗ ΣΕ ΥΨΗΛΕΣ ΣΧΕΤΙΚΑ ΘΕΡΜΟΚΡΑΣΙΕΣ) ΕΠΗΡΕΑΖΕΙ ΣΗΜΑΝΤΙΚΑ ΤΑ ΧΑΡΑΚΤΗΡΙΣΤΙΚΑ ΕΞΑΥΛΩΣΗΣ. ΤΑ ΓΕΝΙΚΑ ΧΑΡΑΚΤΗΡΙΣΤΙΚΑ ΤΗΣ ΕΞΑΡΤΗΣΗΣ ΑΥΤΗΣ ΕΙΝΑΙ: Α) ΜΟΝΟΤΟΝΗΜΕΙΩΣΗ ΤΟΥ ΧΡΟΝΟΥ ΖΩΗΣ ΤΩΝ ΠΟΖΙΤΡΟΝΙΩΝ ΚΑ S-ΠΑΡΑΜΕΤΡΟΥ ΚΑΤΑ ΤΗΝ ΑΝΑΠΤΥΞΗ ΚΡΥΣΤΑΛΛΙΚΩΝ ΚΟΚΚΩΝ ΑΠΛΗΣ ΦΑΣΗΣ ΚΑΙ Β) ΕΜΦΑΝΙΣΗ ΕΛΑΧΙΣΤΟΥ ΣΤΙΣ ΚΑΜΠΥΛΕΣ ΛΟΓΩ ΑΝΑΚΡΥΣΤΑΛΛΩΣΗΣ ΜΕΤΑΣΤΑΘΩΝ ΚΡΥΣΤΑΛΛΙΚΩΝ ΦΑΣΕΩΝ, ΕΜΦΑΝΙΣΘΕΝΤΩΝ ΣΤΑ ΠΡΩΙΜΑ ΣΤΑΔΙΑ ΤΗΣ ΚΡΥΣΤΑΛΛΩΣΗΣ
Study of the performance of the ATLAS monitored drift tube chambers under the influence of heavily ionizing -particles
No full textThe MDT chambers of the ATLAS Muon Spectrometer will operate in a heavy LHC background environment mainly from photons and neutrons. The ionization produced by neutron recoils is much higher than the one from photons or muons and can be simulated by the use of alpha particles. A systematic study of the behavior of the ATLAS Monitored Drift Tubes (MDTs) under controlled irradiation has been performed. The presence of alpha particles results in the reduction of the gas gain due to space charge effects. The gas gain reduction has been studied in a single tube set up using a well controlled radium (/sup 226/Ra) source in order to enrich the tube gas (Ar/CO/sub 2/) with the alpha emitter /sup 220/Rn and irradiate the tubes internally. The results are confronted with Garfield simulations
MicroRNAs in Female Malignancies
No full textMicroRNAs (miRNAs) are endogenous 22-nucleotide RNAs that can play a fundamental regulatory role in the gene expression of various organisms. Current research suggests that miRNAs can assume pivotal roles in carcinogenesis. In this article, through bioinformatics mining and computational analysis, we determine a single miRNA commonly involved in the development of breast, cervical, endometrial, ovarian, and vulvar cancer, whereas we underline the existence of 7 more miRNAs common in all examined malignancies with the exception of vulvar cancer. Furthermore, we identify their target genes and encoded biological functions. We also analyze common biological processes on which all of the identified miRNAs act and we suggest a potential mechanism of action. In addition, we analyze exclusive miRNAs among the examined malignancies and bioinformatically explore their functionality. Collectively, our data can be employed in in vitro assays as a stepping stone in the identification of a universal machinery that is derailed in female malignancies, whereas exclusive miRNAs may be employed as putative targets for future chemotherapeutic agents or cancer-specific biomarkers. © The Author(s) 2019
Cosmic Radiation Intensity Measurements Using TL Dosimeters at Various Mountain Altitudes
No full textSearching for decaying axionlike dark matter from clusters of galaxies
No full textWe consider the possibility of constraining the lifetime of radiatively decaying dark matter particles in clusters of galaxies inspired from generic axions of the Kaluza-Klein type. Such axions have been invoked as a possible explanation for the coronal X-ray emission from the Sun. These axions, or similar particles, can be produced inside stars and some of them remain confined by the deep gravitational potential of clusters of galaxies. Specifically, we consider regions within merging galaxy clusters (Abell 520 and the "Bullet Cluster"), where gravitational lensing observations have identified massive, but baryon poor, structures. From an analysis of X-ray observations of these mass concentrations, and the expected photon spectrum of decaying solar KK-axions, we derive lower limits to the lifetime of such axions of tau approx. 10^23 sec. However, if KK-axions constitute less than a few percent of the dark matter mass, this lifetime constraint is similar to that derived from solar KK-axions
Sex-specific trends in prevalence of childhood asthma over 30 years in Patras, Greece
No full textAim: According to four surveys conducted during 1978-2003, the prevalence of childhood asthma and wheezing has risen in the city of Patras, Greece, albeit at a decelerating rate. We examined sex-specific wheeze and asthma prevalence in the same urban environment in 2008. Methods: A cross-sectional parental questionnaire survey was performed in 2008 among third and fourth grade schoolchildren (8-9 year old), which was identical to previously conducted surveys in 1978 (n = 3003), 1991 (n = 2417), 1998 (n = 3076) and 2003 (n = 2725). Results: The prevalence of current wheeze and asthma in 1978, 1991, 1998, 2003 and 2008 (n = 2688) was 1.5%, 4.6%, 6.0%, 6.9% and 6.9%, respectively (p for trend <0.001). Respective values for lifetime (ever had) wheeze and asthma in the 1991-2008 surveys were 8.0%, 9.6%, 12.4% and 12.6% (p for trend <0.001). The male:female ratio of current and lifetime wheeze and asthma increased during the 30-year surveillance period (p for trend <0.001). Irrespective of sex, diagnosed asthma declined among current wheezers by 17% (p < 0.001), but not among non-current ones (6.7%, p = 0.16) during 2003-2008. Conclusions: Childhood wheeze and asthma have reached a plateau in an urban environment in Greece, while the male:female ratio increased. Asthma diagnosis declined among schoolage but not preschool wheezers during 2003-2008. © 2011 The Author(s)
Author Correction: FANCD2-FANCI surveys DNA and recognizes double- to single-stranded junctions
No full textCorrection to: Naturehttps://doi.org/10.1038/s41586-024-07770-w Published online 31 July 2024 In the version of the article initially published, we omitted to include in the Methods section entitled “Electron microscopy and image processing” the method for the purification of untagged D2–I protein for cryoEM. The HTML and PDF versions of the article have now been updated
OBSTRUCTIVE SLEEP APNEA SYNDROME AS A CAUSE OF SECONDARY ARTERIAL HYPERTENSION IN YOUNG ADULTS
No full text
