Search

We present the identification and photometric analysis of 30 new low mass ratio (LMR) totally eclipsing contact binaries found in Catalina Sky Survey data. The LMR candidates are identified using Fourier coefficients and visual inspection. We perform a detailed scan in the parameter plane of mass ratio (q) versus inclination (i) using phoebe -0.31 scripter to derive the best (q, i) pair for the initial models. The relative physical parameters are determined from the final model of each system. A Monte Carlo approach was adopted to derive the parameter errors. The resulting parameters confirm the identification. The approximate absolute physical parameters of the systems are estimated based on the light-curve solutions and Gaia Early Data Release 3 distances. 12 out of 30 new systems have fill-out factors $f\gt 50{{\ \rm per\ cent}}$ and q ≤ 0.25 (deep contact LMR systems), and eight of them, to within errors, are extreme LMR deep systems with q ≤ 0.1. We discuss the evolutionary status of the 30 LMR systems in comparison with the most updated catalogue of LMR systems from the literature. The scenario of the LMR systems as pre-merger candidates forming fast rotating stars is investigated for all systems, new and old, based both on Hut’s stability criteria and critical instability mass ratio (qinst) relation. CSS$\_$J075848.2+125656, with q/qinst = 1.23 ± 0.23, and CSS$\_$J093010.1−021624, with q/qinst = 1.25 ± 0.23, can be considered as merger candidates. $$\begin{eqnarray} \_ \end{eqnarray}$$

Multidisciplinary Design Optimization (MDO) is a method that has shown many promising results in the development of complex engineered products. To this date, research on MDO has been extensive, but at the same time, very few publications have addressed the aspect of how it can be taught to students and young professionals. In this light, this paper aims to present the experiences of the authors in respect to the development and management of an MDO course at Linköping University. First, this work will describe the authors' teaching approaches, and in particular, it will present the various educational activities that have been considered over the years as well as the lessons learnt. Secondly, this work will attempt to investigate how students perceive a set of common MDO concepts, and more specifically, it will present an analysis based on the results of two surveys that took place in 2016 and 2020, respectively. Given the above foundation, this paper will try to establish guidelines regarding the activities which are suitable for teaching each concept, while finally, it will also touch upon the challenges as well as the solutions for adjusting an MDO course to a distance learning mode.

Η μελέτη των διπλών εκλειπτικών συστημάτων παραμένει ένα από τα πιο ενδιαφέροντα ερευνητικά πεδία της αστροφυσικής γιατί παρέχει την πιο ακριβή μέθοδο υπολογισμού των βασικών αστρικών μεγεθών (μαζών, ακτίνων, θερμοκρασιών) αλλά και κάθε μορφής αστρικής δραστηριότητας που αναπτύσσεται (κηλίδες, δίσκοι προαύξησης ύλης, αναπάλσεις) μέσα από τη μακρόχρονη μεταβολή της περιόδου τους. Επιπλέον επιτρέπει τον έλεγχο των θεωριών αστρικής εξέλιξης μέσα από την αλληλεπίδρασή τους αλλά και την πρόβλεψη παρουσίας τρίτων σωμάτων αστρικής ή μη φύσης.Σε αυτήν τη διατριβή μελετάται μία ιδιαίτερη κατηγορία διπλών εκλειπτικών συστημάτων σε επαφή, τα W UMa τα οποία αποτελούνται από αστέρες κύριας ακολουθίας οι οποίοι βρίσκονται σε υπερεπαφή, και χαρακτηρίζονται από τις μικρότερες περιόδους κι άρα από τη μικρότερη στροφορμή. Σκοπός της είναι τόσο η παρατηρησιακή μελέτη και ανάλυση συστημάτων W UMa που παρουσιάζουν ιδιαίτερο ενδιαφέρον όσο και η ανάγκη ανάπτυξης μεθοδολογίας μοντελοποίησης για την εξαγωγή της μέγιστης πληροφορίας και ελέγχου των εξαγόμενων φυσικών παραμέτρων κάτω από την εφαρμογή σύγχρονων στατιστικών μεθόδων.Το πρώτο μέρος της επικεντρώνεται στη σκιαγράφηση του θεωρητικού επιστημονικού πλαισίου περιγραφής των διπλών εκλειπτικών αστρικών συστημάτων σε επαφή. Το Κεφάλαιο1 αναφέρεται στη γεωμετρία των τροχιών και στη φυσική των αστέρων του συστήματος, στην περιγραφή του μοντέλου Roche και στην αλληλεπίδραση των μελών καθώς και στη δυναμική των συστημάτων όπως αυτή εκδηλώνεται από την παρατηρούμενη μεταβολή της περιόδου του.Το Κεφάλαιο 2 αναφέρεται στις φωτομετρικές παρατηρήσεις που έγιναν κατά την διάρκεια της παρούσας διατριβής καθώς και στις αυτοματοποιημένες μεθόδους επεξεργασίας και ανάλυσης των παρατηρησιακών αστρονομικών δεδομένων οι οποίες αναπτύχθηκαν. Το Κεφάλαιο 3περιγράφει τις σύγχρονες τεχνικές μοντελοποίησης και τα προγράμματα ανάλυσης για τηλύση του αντίστροφου προβλήματος. Το Κεφάλαιο 4 περιγράφει την αναζήτηση, εξόρυξη και αυτόματη ανάλυση δεδομένων από παρατηρησιακές αστρονομικές επισκοπήσεις και την εφαρμογή του κώδικα τεχνητών νευρωνικών δικτύων EBAI.Το δεύτερο μέρος επικεντρώνεται στην αναλυτική μελέτη επιλεγμένων στενών διπλών συστημάτων W UMa με ιδιαίτερο ενδιαφέρον. Σε όλα τα επιλεγμένα συστήματα παρουσιάζεται η φωτομετρική τους μελέτη κάτω από το φως νέων BV RcIc παρατηρήσεων, η μελέτη της περιόδου, το εξαγόμενο μοντέλο σε συνδυασμό με φασματοσκοπικά δεδομένα, ο προσδιορισμός τροχιακών και φυσικών παραμέτρων και η θέση τους σε εξελικτικά διαγράμματα.Επίσης γίνεται η διερεύνηση του προτεινόμενου μοντέλου για μοναδικότητα στο χώρο των λύσεων μέσα από σάρωση με εισαγωγή διαταραχών ή άλλων στατιστικών μεθόδων και ο στατιστικός προσδιορισμός των σφαλμάτων των παραμέτρων. Συγκεκριμένα στο Κεφάλαιο5 παρουσιάζεται το ενοποιημένο μοντέλο του συστήματος TY Boo δύο κηλίδων που ερμηνεύει τη συμπεριφορά του την περίοδο 1969-2011 και τη μελέτη της περιόδου του. Σύμφωνα με αυτό το σύστημα TY Boo ανήκει στην υποκατηγορία W των W UMa με μικρό βαθμό επαφής f = (7.6 ±0.8)% και η μακρόχρονη μελέτη της περιόδου του δείχνει μακροχρόνια μείωση (dP/dt = −3.65x10^−8 d yr^−1 ) και μία περιοδικότητα (P3 = 58.9yrs, A = 0.0254 days)η οποία, χωρίς να αποκλείεται η παρουσία τρίτου σώματος, ερμηνεύεται με ενεργό μαγνητικό κύκλο που προκαλεί την εμφάνιση κηλίδων.Στο Κεφάλαιο 6 παρουσιάζεται για πρώτη φορά η λεπτομερής ανάλυση του συστήματος WUMa, FI Boo το οποίο ταξινομείται στην υποκατηγορία W, με βαθμό επαφής f = (50.15 ±8.10) %, κάτω από την παρουσία τρίτου σώματος το οποίο μπορεί να παίζει σημαντικό ρόλο στη δημιουργία και την εξέλιξή του. Σύμφωνα με το προτεινόμενο μοντέλο προσδιορίζονται οι μάζες Mh =0.40 ± 0.05 Msun , Mc =1.07 ± 0.05 Msun , και οι θερμοκρασίες Th = 5746±33Κ, Tc = 5420±46 Κ των αστέρων-μελών του καθώς και των προγεννητόρων τους (1.71 ±0.10 Msun και 0.63 ± 0.01 Msun , αντίστοιχα) και διερευνάται το εξελικτικό στάδιο του αστέρα με τη μεγαλύτερη μάζα μέσα από ισόχρονες.Στο Κεφάλαιο 7 διερευνάται σε βάθος το σύστημα σε επαφή V1003 Her, το οποίο χαρακτηρίζεται από μεταβολή μικρού πλάτους, με πολλαπλά μοντέλα για τα οποία ελέγχεται η σταθερότητα των με ανεξάρτητες μεθόδους. Το επικρατέστερο από αυτά δείχνει ότι το σύστημα είναι W UMa με βαθμό επαφής f = (36±10) %, με ασυνήθιστα άνισες θερμοκρασίες μεταξύ των αστέρων του 550 Κ, και λόγο μαζών q = 0.373. Η μικρή του κλίση i = 38^o ±1^ο το καθιστά ένα από τα μεγαλύτερης μάζας στην υποκατηγορίας W.Στο Κεφάλαιο 8 εξετάζεται η φύση του διπλού συστήματος HI Dra, η λεπτομερής ανάλυση του οποίου δείχνει ότι είναι W UMa με μικρό βαθμό επαφής f = (24 ± 4) % και διαφορά θερμοκρασίας μεταξύ των αστέρων του 330 Κ. Προτείνονται και διερευνώνται εξονυχιστικά δύο μοντέλα με κηλίδες από τα οποία επικρατέστερο, με ψυχρή κηλίδα πάνω στον μικρότερης μάζας και ψυχρότερο αστέρα- τον τοποθετεί στην υποκατηγορία Α. Προσδιορίζονται οι φυσικές παράμετροι των μελών του (M = 1.72 ± 0.08Msun , Mc = 0.43 ± 0.02 Msun , Rh =1.98 ± 0.03Rsun , Rc = 1.08 ± 0.02 Rsun , Lh = 9.6 ± 0.1 Lsun , Lc = 2.4 ± 0.1 Lsun ) και των προγεννητόρων τους (1.11 ± 0.03 Msun και 2.25 ± 0.07 Msun, αντίστοιχα) και προσεγγίζεται η ηλικία του συστήματος σε 2.4 Gyr .Τέλος στο Κεφάλαιο 8 παρουσιάζονται τα πρώτα αποτελέσματα από τις φωτομετρικές παρατηρήσεις με το τηλεσκόπιο Αρίσταρχος 2.3 m, διπλών εκλειπτικών συστημάτων με ιδιαίτερο ενδιαφέρον που ανακαλύφθηκαν ή παρατηρήθηκαν από την διαστημική αποστολή Kepler με περιόδους περιφοράς < 0.45 d, τα οποία παρουσιάζουν ασυμμετρίες στην καμπύλη φωτός, χρονικές μεταβολές των εκλείψεων των μελών τους ή είναι εν δυνάμει τριπλά συστήματα. Τα πρώτα αποτελέσματα αφορούν τα συστήματα KIC 11246163 και KIC 4563150τα οποία ταξινομούνται ως συστήματα τύπου W UMa, W υποκατηγορίας με πιθανό τριτο συνοδό.

We present 126 eclipsing binary candidates among 4683 Catalina Sky Surveys (CSS) detached and semi-detached eclipsing binary systems (EBs) showing cyclic or quadratic period variations over a 12 yr time span. By using inverse Gaussian profiles of the eclipses coupled with a Markov chain Monte Carlo procedure, times of minima (ToM) were calculated and diagrams with eclipse timing variations (ETVs) were constructed. Numerical tests were performed, involving synthetic EBs with period variations generated by the PHOEBE 2.0 engine and actual data for EBs with well-known period variations from the literature, to verify that the calculation of ToM variations for our CSS systems is reliable. A total of 63 out of the 126 EBs show likely cyclic ETVs, while the remainder present quadratic behaviour instead. Periods, amplitudes, period change rates, and associated errors were determined by using sinusoidal and parabolic models. 12 out of the 63 EBs (19 per cent) that appear to exhibit periodic ETVs are low-mass candidates. Additionally, four out of 126 also have maximum quadrature light variations. The possibility that the cyclic variations are caused by the light traveltime effect due to the presence of a tertiary companion is investigated. The possible nature of the quadratic ETVs is also discussed.

This paper presents a multidisciplinary design optimization framework applied to the development of unmanned aerial vehicles with a focus on radar signature and sensor performance requirements whil ...

Increasing rates of body weight of children has become a motivation for investigating active transportation to school during the past years. Lack of proper data covering different geographical contexts is a problem seen in the literature of this subject. The present paper reports the findings of a recent survey on nine cities in seven European countries funded by the European Commission. The objective of the survey was to provide data covering several topics in relation with active commuting to school and body mass index, such as parental perceptions of safety and security, neighborhood facilities, land use characteristics, etc. in different regions of Europe in a way that cross-sectional comparisons between regions and city sizes is facilitated. For that, 2735 children/parents were handed out questionnaires, from whom 1424 filled out the questionnaires (response rate: 52%). This led to 1304 validated questionnaires. The respondents studied in 21 elementary schools of Foggia, Italy; Berlin, Germany; Thessaloniki, Greece; Rijeka, Croatia; Utrecht, The Netherlands; Łódź, Poland; Konstantynow, Poland; Malatya, Turkey, and Doğanşehir, Turkey as of March 2016 until January 2017. The survey instrument enables development of continuous and categorical variables for empirical research with strong focus on the built environment using the aggregate data provided by this study. It is expected that the output data eases production of knowledge about less-studied European contexts as well as cross-sectional comparison of results with more studied areas of Western Europe.

High extinction and crowding create a natural limitation for optical surveys towards the central regions of the Milky Way, where the gas and dust are mainly confined. Large-scale near-infrared (IR) surveys of the Galactic plane and bulge are a good opportunity to explore open scientific questions as well as to test our capability to explore future data sets efficiently. Thanks to the VISTA Variables in the Vía Láctea (VVV) ESO public survey, it is now possible to explore a large number of objects in those regions. This paper addresses the variability analysis of all VVV point sources having more than 10 observations in VVVDR4 using a novel approach. In total, the near-IR light curves of 288 378 769 sources were analysed using methods developed in the New Insight Into Time Series Analysis project. As a result, we present a complete sample having 44 998 752 variable star candidates (VVV-CVSC), which include accurate individual coordinates, near-IR magnitudes (Z,Y,J, and Hs), extinctions A(Ks), variability indices, periods, amplitudes, among other parameters to assess the science. Unfortunately, a side effect of having a highly complete sample, is also having a high level of contamination by non-variable (contamination ratio of non-variables to variables is slightly over 10:1). To deal with this, we also provide some flags and parameters that can be used by the community to decrease the number of variable candidates without heavily decreasing the completeness of the sample. In particular, we cross-identified 339 601 of our sources with Simbad and AAVSO data bases, which provide us with information for these objects at other wavelengths. This subsample constitutes a unique resource to study the corresponding near-IR variability of known sources as well as to assess the IR variability related with X-ray and gamma-ray sources. On the other hand, the other ${\sim }99.5{{\ \rm per\ cent}}$ sources in our sample constitutes a number of potentially new objects with variability information for the heavily crowded and reddened regions of the Galactic plane and bulge. The present results also provide an important queryable resource to perform variability analysis and to characterize ongoing and future surveys like TESS and LSST.

The discovery and characterization of Algol eclipsing binaries (EAs) provide an opportunity to contribute for a better picture of the structure and evolution of low-mass stars. However, the cadence of most current photometric surveys hinders the detection of EAs since the separation between observations is usually larger than the eclipse(s) duration and hence few measurements are found at the eclipses. Even when those objects are detected as variable, their periods can be missed if an appropriate oversampling factor is not used in the search tools. In this paper, we apply this approach to find the periods of stars cataloged in the Catalina Real-Time Transient Survey (CRTS) as EAs having unknown period (EA$_{\rm up}$). As a result, the periods of $\sim 56\%$ of them were determined. Eight objects were identified as low-mass binary systems and modeled with the Wilson \& Devinney synthesis code combined with a Monte-Carlo Markov Chain optimization procedure. The computed masses and radii are in agreement with theoretical models and show no evidence of inflated radii. This paper is the first of a series aiming to identify suspected binary systems in large surveys., 11 pages, 7 figures

There is increasing evidence to suggest an association between depression and inflammation, with patients suffering from immune mediated-disorders exhibiting higher levels of depression. Inflammation in depression is a potential target for the development of novel treatment strategies. The present study presents a clinical case in which a patient with an underlying inflammatory condition acutely developed a severe depressive episode resulting in a sudden, dramatic change in their clinical picture. This case, with no similar case reports being in the literature thus far, at least to the best of our knowledge, highlights the increasing consideration that there may be a causative role between neuro-inflammation and depression. This study reports the case of a 40-year-old male with acute lymphoblastic leukaemia (ALL) and no previous psychiatric history, who developed an acute onset of a severe depressive episode in the context of the immune-mediated graft-versus-host disease (GVHD). GVHD is a complication of allogeneic hematopoietic cell transplantation, which the patient had undergone, for the treatment of his ALL. The rapid onset of depression could be explained by the neuroinflammatory processes occurring in GVHD. This provides a clinical example for the possible role of the immune system in depression, and clinicians should be aware of this association.

Over the last years, Unmanned Aerial Vehicles (UAVs) have gradually become a more efficient alternative to manned aircraft, and at present, they are being deployed in a broad spectrum of both milit ...

Technetium-99, a pure β-emitter with Emax =294 keV, is one of the most significant (t1/2 =2.1×105 y) nuclear waste isotopes, produced by the fission of U with a yield of 6%. Under normal environmental conditions, it is mostly encountered as the pertechnetate ion, TcO4 -, which is highly soluble and consequently mobile in water. For this reason, its monitoring into groundwater is a statutory requirement for every nuclear license site. Because of its relatively low concentration in environmental samples, current determination methods of 99Tc involve several steps, such as chemical separation from the matrix, purification and source preparation, prior to radiometric (e.g. liquid scintillation counting) or mass spectroscopic (e.g. inductively coupled plasma mass spectroscopy) determination. The detection of 99Tc may take up to several days, thus making these techniques inappropriate for an emergency situation. Hence, We report on the development of a sensor for the real time monitoring of 99Tc in groundwater based on the Quartz Crystal Nanobalance (QCN). The QCN is a piezoelectric resonator, which oscillates in a resonant frequency fs when an electric potential is applied across its body. It is capable of measuring very small changes in mass at its surface, through the change of the resonant frequency. We modify it to respond exclusively to the presence of TcO4 -, by application of a novel Ag-4,4bipyridine metal-organic framework thin film built layer-by-layer on a self-assembled monolayer of 4-mercaptopyridine on the gold surface. The film’s structure is characterised by several techniques such as XPS, AFM and XRD and we evaluate its response and selectivity by monitoring the changes in the resonant frequency as a function of the concentration of ReO4 -, which is a non-radioactive chemical surrogate for TcO4 -. Finally, we model the adsorption of ReO4 - and other interferences with adsorption isotherms such as Langmuir, Freundlich and Sips.

99Tc, a pure β-emitter with Emax =294 keV, is one of the most significant (t1/2 =2.1×105 y) nuclear waste isotopes, produced by the fission of U with a yield of 6%. Under normal environmental conditions, it is mostly encountered as the pertechnetate ion, TcO4 -, which is highly soluble and consequently mobile in water. For this reason, and because it often is the first contaminant to be present in detectable levels, its monitoring into groundwater is a statutory requirement for every nuclear license site. Because of its relatively low concentration in environmental samples, current determination methods of 99Tc involve several steps, such as chemical separation from the matrix, purification and source preparation, prior to radiometric (e.g. liquid scintillation counting) or mass spectroscopic (e.g. inductively coupled plasma mass spectroscopy) determination. The detection of 99Tc may take up to several days, thus making these techniques inappropriate for an emergency situation. Hence, We report on the development of a sensor for the real time monitoring of 99Tc in groundwater based on the Quartz Crystal Nanobalance (QCN). The QCN is a piezoelectric resonator, which oscillates at a resonant frequency fs when an electric potential is applied across its body. It is capable of measuring very small changes in mass at its surface, through the change of the resonant frequency. We modify it to respond exclusively to the presence of TcO4 -, by application of a novel Ag-4,4bipyridine metal-organic framework thin film built layer-by-layer on a self-assembled monolayer of 4-mercaptopyridine on the gold surface. The film’s structure is characterised by several techniques such as XPS, AFM and XRD and we evaluate its response and selectivity by monitoring the changes in the resonant frequency as a function of the concentration of ReO4 -, which is a non-radioactive chemical surrogate for TcO4 -.

We present an updated catalog of 4680 northern eclipsing binaries (EBs) with Algol-type light-curve (LC) morphology (i.e., with well-defined beginnings and ends of primary and secondary eclipses), using data from the Catalina Sky Surveys. Our work includes revised period determinations, phenomenological parameters of the LCs, and system morphology classifications based on machine-learning techniques. While most of the new periods are in excellent agreement with those provided in the original Catalina catalogs, improved values are now available for ~10% of the stars. A total of 3456 EBs were classified as detached and 449 were classified as semi-detached, while 145 could not be classified unambiguously into either subtype. The majority of the SD systems seem to be comprised of short-period Algols. By applying color criteria, we searched for K- and M-type dwarfs in these data, and present a subsample of 609 EB candidates for further investigation. We report 119 EBs (2.5% of the total sample) that show maximum quadrature light variations over long timescales, with periods bracketing the range 4.5–18 years and a fractional luminosity variance range of 0.04–0.13. We discuss possible causes for this, making use of models of variable starspot activity in our interpretation of the results.

Over the last decade, Unmanned Aerial Vehicles (UAVs) have experienced an accelerated growth, and nowadays they are being deployed in a variety of missions that have traditionally been covered by m ...

This paper presents a data management and visualization tool that was developed in parallel with a Multidisciplinary Design Optimization (MDO) framework in order to enable a more effective use of the obtained results within the Product Development Process (PDP). To this date, the main problem is that the majority of MDO case studies conclude by suggesting a small number of optimal configurations, which do not really hold any meaningful value for the decision makers since they represent only a narrow area of the design space. In this light, the proposed tool aims to provide designers with new possibilities in respect to post-processing of large data sets, and subsequently, to allow the non-technical teams to be engaged and benefit from the use of MDO in the company practices. As an example, an Unmanned Aerial Vehicle (UAV) configurator developed by using the Graphical User Interface (GUI) of MATLAB is herein presented, and it is shown that a tool for handling the results can be the logical next step towards integrating MDO in the manufacturing industry. Overall, this work aims to demonstrate the benefits of the present visualization and management tool as a complementary addition to an existing optimization framework, and also to determine if this approach can be the right strategy towards improving the MDO method for an eventual use in the PDP of complex pro-ducts like UAVs.

This paper presents a Multidisciplinary Design Optimization (MDO) framework that is intended to be employed in the early design stages of Unmanned Aerial Vehicles (UAVs) when the primary focus is o ...

We present the physical properties for 2281 northern eclipsing binary (EB) stars with eclipsing Algol (EA)-type light-curve (LC) morphology, based on data extracted from the Catalina Sky Survey (CSS). Our study is based on the analysis of the Eclipsing Binary via Artificial Intelligence (EBAI) artificial neural network (ANN) tool. An intensive search for the optimal ANN topology was performed. In order to feed the ANN with LCs that are representative of the CSS observations, two independent methods, based on template fitting and on the Two-Gaussian Model, were applied. As a result, five principal physical parameters were determined using only the CSS LCs, namely the temperature ratio, T_2/T_1; the sum of relative radii, ρ_2 + ρ_1; ε sin ω; ε cos ω; and sin i, where e is the eccentricity, ω is the argument of periastron, and i is the orbital inclination. Parameter uncertainties were estimated based on a Monte Carlo approach. When the ANN predictions were out of its training limits (1540 EBs), the parameters of the systems are based on the matching templates technique only. The results are fully in agreement with the expected parameter values for detached EB systems and can be used as initial inputs for advanced and dedicated EB models and/or for statistical purposes.

One of the most significant and challenging problems in actuarial practice, especially for general insurance, is the modelling of the premium pricing process and furthermore its stability. The classical actuarial approach to calculating the premium simply covers the expected claims, with an increase for eventual expected surplus, chosen such that the portfolio can be considered stable. In this paper, we present an alternative model for the premium pricing process of a portfolio consisting of different non-life products. Moreover, a standard decision function for the determination of the premium is proposed based on the recent claim experience and a negative feedback mechanism of the known surplus value. The investigation of the robust stability of the system is performed via a Linear Matrix Inequality (LMI) criterion, permitting extensions of existing results. The novelty of the approach consists in the use of tools from the robust analysis of engineering systems in the insurance pricing process of non‐life products into a discrete-time framework.

Objective. Essential hypertension is associated with reduced pain sensitivity of unclear aetiology. This study explores this issue using the Cold Pressor Test (CPT), a reliable pain/stress model, comparing CPT-related EEG activity in first episode hypertensives and controls. Method. 22 untreated hypertensives and 18 matched normotensives underwent 24-hour ambulatory blood pressure monitoring (ABPM). EEG recordings were taken before, during, and after CPT exposure. Results. Significant group differences in CPT-induced EEG oscillations were covaried with the most robust cardiovascular differentiators by means of a Canonical Analysis. Positive correlations were noted between ABPM variables and Delta (1-4Hz) oscillations during the tolerance phase; in high-alpha (10-12Hz) oscillations during the stress unit and posttest phase; and in low-alpha (8-10Hz) oscillations during CPT phases overall. Negative correlations were found between ABPM variables and Beta2 oscillations (16.5-20Hz) during the posttest phase and Gamma (28.5-45Hz) oscillations during the CPT phases overall. These relationships were localised at several sites across the cerebral hemispheres with predominance in the right hemisphere and left frontal lobe. Conclusions. These findings provide a starting point for increasing our understanding of the complex relationships between cerebral activation and cardiovascular functioning involved in regulating blood pressure changes.

The O’Connell effect is one of the most perplexing challenges in binary studies as it has not been convincingly explained. Furthermore, a simple method to obtain essential parameters for eclipsing binaries exhibiting this effect and to extract information describing the asymmetry in the light curve maxima is needed. We have developed an automated program that characterizes the morphology of light curves by depth of both minima, height of both maxima and curvature outside the eclipses.

Αντικείμενο της διατριβής είναι η μελέτη της δυναμικής συμπεριφοράς μικτών καθ’ ύψος κατασκευών που αποτελούνται από δύο τμήματα, ένα κατώτερο από σκυρόδεμα, και ένα ανώτερο από χάλυβα. Τα δύο υλικά συνεπάγονται δυσκολίες στην ανάλυση των κατασκευών αυτών σύμφωνα με τους ισχύοντες κανονισμούς. Η παρούσα διατριβή επιχειρεί να προτείνει λύσεις στα προβλήματα (i) της αποσύζευξης των δύο τμημάτων, και (ii) του καθορισμού συντελεστών απόσβεσης κατά την συζευγμένη ανάλυση. Η μελέτη του σφάλματος αποσύζευξης γίνεται αριθμητικά, και αφορά ένα εύρος δυναμικών χαρακτηριστικών των δύο τμημάτων της κατασκευής. Παράγονται καμπύλες, οι οποίες επιτρέπουν την πρόβλεψη του σφάλματος αποσύζευξης σε προκαταρκτικό στάδιο της μελέτης της κατασκευής. Για τις περιπτώσεις που το σφάλμα αποσύζευξης είναι πολύ μεγάλο, αναζητούνται εναλλακτικά ισοδύναμοι συντελεστές απόσβεσης προκειμένου να εφαρμοστούν σε μια συζευγμένη ανάλυση της κατασκευής. Οι συντελεστές αυτοί έχουν δύο μορφές, ιδιομορφικοί και ενιαίοι, και καταφέρνουν πολύ καλά να προσεγγίσουν την πραγματική απόκριση της κατασκευής.

Our thinking about eclipsing binary stars has undergone a tremendous change in the last decade. Eclipsing binary stars are one of nature’s best laboratories for determining the fundamental physical properties of stars and thus for testing the predictions of theoretical models. Some of the largest ongoing variable star surveys include the Catalina Real-time Transient Survey (CRTS) and the VISTA Variables in the Vía Láctea survey (VVV). They both contain a large amount of photometric data and plenty of information about eclipsing binaries that wait to be extracted and exploited. Here we briefly describe our efforts in this direction.

In order to reduce toxicity and to enhance anticancer activity of nitrogen mustards, three hybrid steroidal esters were synthesized and tested in vitro against human pancreatic cancer cells expressing uridine phosphorylase (UPase). The inhibition potency against a target protein implicated in the chemotherapy of solid tumors, such as UPase, is of fundamental importance in the design and synthesis of new anticancer drugs.MTT colorimetric assay and molecular docking were employed for the in vitro and in silico drug evaluation, respectively.A difference in cell sensitivity was found, which followed the known different UPase expression in the cell lines. Molecular docking studies on UPase protein, revealed the tested compounds to be bound to the binding cavity of the protein, with different affinity. Between the two D-modified compounds, the D-homo-aza (lactam)-hybrid compound (C2) was found to interact with the protein in a more efficient way.The molecular docking data were in accordance with the in vitro results, where the lactam steroid alkylator showed significantly higher cytostatic and cytotoxic activity than the non-D-modified compounds, which also correlated with the level of UPase expression in the pancreatic cancer cells.

In this paper, we design a model for the insurance pricing process of a portfolio of different (dependent or independent) non-life products. A standard decision function for the determination of the premium is proposed which use the recent claim experience and a negative feedback mechanism of the known surplus value. The model assumes a time-varying, bounded delay factor, time-varying parameters and different types of norm-bounded uncertainties. Finally, a Linear Matrix Inequality (LMI) criterion is derived for the investigation of the robust stability of the system. For the first time, a classical tool for the robust control analysis of engineering systems has been applied for the insurance pricing process of non-life products, extending further the existing literature. An example with 2 dependent non-life products illustrates the results of the paper.

Modified steroidal derivatives (PK11-PK14) of p-bis(2-chloroethyl)aminophenyl propenate (PK15) were used to study their antitumour activity on Lewis lung carcinoma (LLC) and their effect on sister chromatid exchanges (SCEs) and human lymphocyte proliferation kinetics.LLC was tested in this study. C57BL mice were used for in vivo chemotherapy evaluation and the antitumour activity was assessed. Lymphocyte cultures were used to study the genotoxic effect in vitro.PK15 and PK11 were the most effective against LLC, causing significant inhibition of tumour growth. PK11 and PK15 induced significant increase in SCE rates. A correlation was observed between the cytogenetic effect and the antitumour effectiveness.The order of the antitumour effectiveness of PK11-PK15 resembled the order of the cytogenetic damage induced by the same compounds in vitro.

The aims of the study were: (1) to determine the quality of the hard and soft tissues formed in segments treated with coronally positioned flaps alone (CPF group) or combined with a polylactic acid resorbable membrane (guided tissue regeneration--GTR group) in wide type defects (canine teeth), and (2) to evaluate the behaviour of the newly regenerated tissues to an experimentally induced inflammation initiated by microbial plaque at the submarginal level in recession type defects (premolar teeth).The randomized block design was used in the study, with each dog receiving both treatments (GTR and CPF). Gingival recession defects were surgically created in the 2nd and 4th mandibular premolars and, after 10 weeks, also in the maxillary canines of three dogs. The defects in the premolar area were created earlier than the defects in the canine teeth so that both areas would be ready for biopsy at the same time. Two months after the creation of the defects the exposed roots in the control group of teeth were surgically covered with coronally positioned flaps only (CPF group), and in the test group of teeth a coronally positioned flap was used in combination with a resorbable membrane (GTR group). In the premolar teeth only, after a healing period of five months, cotton ligatures were placed intrasulcularly and these areas were left without plaque control for 10 weeks. Following this, biopsies were taken from the canines and the premolars in order to examine (1) the quality of the hard and soft tissues formed after five months of healing in the canine teeth and (2) the response of the newly formed tissues to microbial accumulation induced by the subgingival ligature placement.In the wide defects of the canine teeth, the use of the membrane produced a mean new attachment formation of 44%, while the repositioned flap technique produced 22% new attachment. The regeneration of bone was limited to the apical area for both techniques and amounted to 15% and 10%, respectively. In the narrow defects of the premolars both techniques produced comparable mean root coverage percentages. The inflammatory conditions created in the study led to a comparable loss of mean clinical attachment and an increase in tissue recession and the extent of the inflammatory process for both groups.The use of resorbable membranes for the treatment of wide recession type defects in the canine teeth (GTR group) produced significantly better clinical results, with higher mean root coverage and increased regenerative capacity of the periodontal tissues, compared with the coronally positioned flap technique (CPF group). Additionally, the regenerated tissues created after the use of both techniques in narrow recession defects (premolar teeth) demonstrated comparable resistance to the microbial accumulation conditions created.

Recent structure-antileukemic activity studies showed that the steroidal part of complex molecules containing DNA alkylators does not play only the role of the "biological carrier". New such compounds designed to possess an allylic 7-ketone showed enhanced antileukemic potency compared with derivatives with a simple steroidal skeleton. In order to investigate whether the enhancement of the antileukemic potency is attributed to the introduction of the 7-ketone or to the Delta5-7-keto conjugated steroidal system we decided to reduce the Delta5 double bond. The 5alpha-7-keto-steroidal skeletons synthesized were tethered to chlorambucil and phenyl acetic acid's nitrogen mustard and studied against leukemia P338 in vivo. The reduction of the double bond had a negative impact on the antileukemic potency since the comparative study of the novel derivatives showed that a series of very potent Delta 5-7-keto-steroidal esters were converted by this modification to compounds with marginally accepted activity.

Gamma-irradiation leads to apoptosis and cell cycle arrest in eukaryotic cells. Olomoucine is a novel purine analog acting as a cyclin-dependent kinase inhibitor. The effects of olomoucine in gamma-irradiation mediated cell growth inhibition and apoptosis were studied in the Raji cell line (Burkitt's lymphoma). Gamma-irradiation caused a G2 arrest, increasing the G2/M fragment of the cells. Apoptosis by gamma-irradiation was apparent both by DNA-electrophoresis and PARP-1 cleavage. The combination of olomoucine with irradiation caused an increased G2 arrest and decreased cell survival and DNA synthesis in the non-apoptotic fraction of the remaining cells. Irradiation, as well as olomoucine and the combination of both, induced apoptosis. It seems that olomoucine delays the apoptotic process and inhibits DNA fragmentation, but it decreased survival, cell cycle progression and proliferation of irradiated cells.

Traditional bowel preparation before colonoscopy involves lavage with approximately 4L of polyethylene glycol (PEG)-electrolyte solution. Only a few studies have been published evaluating the use of cisapride in routine bowel preparation.We conducted a blinded, placebo-controlled trial with the prokinetic agent, cisapride, in addition to standard PEG-electrolyte lavage. Of 115 patients undergoing colonoscopy, 58 were randomized (double-blind) to PEG plus cisapride (10 mg per os thrice per day three days before the procedure and one 10-mg dose on the morning of the procedure) and 57 to PEG plus a placebo of identical appearance. The adequacy of the preparation was scored on a four-point grading scale for each anatomic-segment and for the overall impression. A questionnaire was also used to assess each patient's symptoms during lavage.The difference in the overall score between the two groups was not significant (p=0.21). The quality of bowel preparation was significantly better in transverse (p=0.001), ascending (p=0.0053), and cecum (p=0.0001) in the cisapride group than in the placebo group. The differences in symptoms scores between the two groups were not significant in nausea, abdominal cramps and bloating but there was improvement in symptom score of vomiting in cisapride group (p=0.0422).The administration of cisapride to patients undergoing colonic lavage may be an effective adjuvant to PEG-electrolyte solution particularly with respect to increase patient acceptability.