Dark Energy: The Shadowy Reflection of Dark Matter?

In this article, we review a series of recent theoretical results regarding a conventional approach to the dark energy (DE) concept. This approach is distinguished among others for its simplicity and its physical relevance. By compromising General Relativity (GR) and Thermodynamics at cosmological scale, we end up with a model without DE. Instead, the Universe we are proposing is filled with a perfect fluid of self-interacting dark matter (DM), the volume elements of which perform hydrodynamic flows. To the best of our knowledge, it is the first time in a cosmological framework that the energy of the cosmic fluid internal motions is also taken into account as a source of the universal gravitational field. As we demonstrate, this form of energy may compensate for the DE needed to compromise spatial flatness, while, depending on the particular type of thermodynamic processes occurring in the interior of the DM fluid (isothermal or polytropic), the Universe depicts itself as either decelerating or accelerating (respectively). In both cases, there is no disagreement between observations and the theoretical prediction of the distant supernovae (SNe) Type Ia distribution. In fact, the cosmological model with matter content in the form of a thermodynamically-involved DM fluid not only interprets the observational data associated with the recent history of Universe expansion, but also confronts successfully with every major cosmological issue (such as the age and the coincidence problems). In this way, depending on the type of thermodynamic processes in it, such a model may serve either for a conventional DE cosmology or for a viable alternative one.Comment: Review article, 38 pages, 5 figures, accepted for publication in Entrop

Η επίδραση ενός προγράμματος θεραπευτικών ασκήσεων σε κλινικές και λειτουργικές παραμέτρους ασθενών με αυχεναλγία μη ειδικής αιτιολογίας

Εισαγωγή: Η αυχεναλγία αποτελεί ένα ιδιαίτερα συχνό πρόβλημα που εμφανίζεται σε μεγάλο μέρος του ενήλικου πληθυσμού με συνοδές διαταραχές λειτουργικότητας. Για τη διαμόρφωση ενός κατάλληλου πλάνου θεραπείας και μιας αποτελεσματικής αποκατάστασης, είναι σημαντική η ολοκληρωμένη αξιολόγηση των ασθενών μέσω συνδυασμού λήψης ιστορικού, κλινικών δοκιμασιών, ερμηνείας απεικονιστικών δεδομένων (CT scan, MRI, ακτινογραφίες), αλλά και συμπλήρωση ερωτηματολογίων από τους ασθενείς. Καθώς ο αυχενικός πόνος επηρεάζει σημαντικά την καθημερινότητα και την ποιότητα ζωής του ατόμου, σκοπός της παρούσας εργασίας ήταν να διερευνήσει την επίδραση ενός προγράμματος θεραπευτικών ασκήσεων στην ποιότητα ζωής ασθενών που πάσχουν από χρόνια αυχεναλγία μη ειδικής αιτιολογίας. Μεθοδολογία: Στη μελέτη συμμετείχαν 40 ασθενείς (23 άνδρες και 17 γυναίκες). Μέσω ειδικών ερωτηματολογίων αξιολογήθηκε η επίδραση ενός προγράμματος θεραπευτικών ασκήσεων, διάρκειας 2 εβδομάδων και 10 συνολικά συνεδριών, σε ασθενείς με χρόνιο μη ειδικό πόνο του αυχένα. Το πρόγραμμα περιελάμβανε ασκήσεις μυϊκής ενδυνάμωσης, μυϊκές διατάσεις, και ασκήσεις για τη βελτίωση της λειτουργικότητας. Αποτελέσματα: H παρούσα μελέτη έδειξε ότι το πρόγραμμα θεραπευτικών ασκήσεων που ακολουθήθηκε συνέβαλε στη μείωση του πόνου και στη βελτίωση της λειτουργικότητας και της ποιότητας ζωής των ασθενών. Συμπέρασμα: Η συμμετοχή σε προγράμματα θεραπευτικής άσκησης που συνδυάζουν ασκήσεις ενδυνάμωσης και βελτίωσης της ελαστικότητας των μυών οδηγεί σε θετικά κλινικά αποτελέσματα σε ασθενείς που πάσχουν από χρόνια αυχεναλγία μη ειδικής αιτιολογίας.Ιntroduction:Neck pain is an extremely common problem in a large part of the adult population with accompanying functional disorders. For an effective rehabilitation and a treatment plan, the comprehensive assessment of the patients is very important, with the combination of primarily taking a medical history, clinical tests, interpretation of imaging methods (CT scan, MRI, X-rays), but also filling out questionnaires from the patients. Neck pain significantly affects a person's daily life and quality of life and is often a significant obstacle to their activity in society. PURPOSE: The purpose of this research is to investigate the assessment of the quality of life through a program of therapeutic exercises in patients suffering from chronic neck pain of non-specific etiology in order to improve their daily life. Methodology:In order to conduct the research, 40 people (23 males and 17 females) participated. Through research questions, the effect of exercise and the effectiveness of different types of therapeutic exercise in chronic, non-specific neck pain will be investigated. The treatment plan will include: muscle strengthening exercises, muscle stretching, improvement of clinical and functional parameters such as kinesthetic exercises. Results:The measurements taken in the present study (the initial ones as well as the follow up) showed that the interventions of the therapeutic exercises contribute to the improvement of functionality, reduction of pain and generally better physical health of the patients Conclusion:In the present research study, regardless of age and gender, following the treatment plan, neck pain decreased, patients functionally improved on a daily basis both in the short term and in the long term. Participating in therapeutic exercise programs that combine exercises to improve muscle flexibility, increase stabilization and strengthen muscles. Thus, adaptations are created in this way that are beneficial to the health of the patients

Layer-by-Layer Assembly of Clay-Carbon Nanotube Hybrid Superstructures

Much of the research effort concerning layered materials is directed toward their use as building blocks for the development of hybrid nanostructures with well-defined dimensions and behavior. Here, we report the fabrication through layer-by-layer deposition and intercalation chemistry of a new type of clay-based hybrid film, where functionalized carbon nanotubes are sandwiched between nanometer-sized smectite clay platelets. Single-walled carbon nanotubes (SWCNTs) were covalently functionalized in a single step with phenol groups, via 1,3-dipolar cycloaddition, to allow for stable dispersion in polar solvents. For the production of hybrid thin films, a bottom-up approach combining self-assembly with Langmuir-Schaefer deposition was applied. Smectite clay nanoplatelets act as a structure-directing interface and reaction media for grafting functionalized carbon nanotubes in a bidimensional array, allowing for a controllable layer-by-layer growth at a nanoscale. Hybrid clay/SWCNT multilayer films deposited on various substrates were characterized by X-ray reflectivity, Raman, and X-ray photoelectron spectroscopies, as well as atomic force microscopy

Development of a Multi-Enzymatic Biocatalytic System through Immobilization on High Quality Few-Layer bio-Graphene

In this work, we report the green production of few-layer bio-Graphene (bG) through liquid exfoliation of graphite in the presence of bovine serum albumin. Microscopic characterization evaluated the quality of the produced nanomaterial, showing the presence of 3–4-layer graphene. Moreover, spectroscopic techniques also confirmed the quality of the resulted bG, as well as the presence of bovine serum albumin on the graphene sheets. Next, for the first time, bG was used as support for the simultaneous covalent co-immobilization of three enzymes, namely β-glucosidase, glucose oxidase, and horseradish peroxidase. The three enzymes were efficiently co-immobilized on bG, demonstrating high immobilization yields and activity recoveries (up to 98.5 and 90%, respectively). Co-immobilization on bG led to an increase of apparent K(M) values and a decrease of apparent V(max) values, while the stability of the nanobiocatalysts prevailed compared to the free forms of the enzymes. Co-immobilized enzymes exhibited high reusability, preserving a significant part of their activity (up to 72%) after four successive catalytic cycles at 30 °C. Finally, the tri-enzymatic nanobiocatalytic system was applied in three-step cascade reactions, involving, as the first step, the hydrolysis of p-Nitrophenyl-β-D-Glucopyranoside and cellobiose

Management of venous thromboembolism in pregnancy

Venous thromboembolism (VTE) in pregnancy, consisting of deep venous thrombosis (DVT) and pulmonary embolism (PE), is a major factor of maternal mortality. Several patient-specific risk factors along with the physiologic changes of pregnancy promote a state of hypercoagulability in pregnant women. Detailed assessment of all pregnant women can establish a risk profile that would guide clinical decisions, and balance potential therapeutic benefits with side effects. Differentiating between physiologic changes of pregnancy and symptoms of VTE can be challenging and warrants meticulous clinical evaluation. Timely and accurate diagnosis of VTE with proper imaging is essential for its management, and systemic anticoagulation remains the cornerstone of VTE prevention and therapy. Furthermore, advanced invasive treatment options such as inferior vena cava filters and thrombectomy can be considered for complex cases. Importantly, the risk of systemic anticoagulation should be balanced against the risk of VTE-associated morbidity and mortality for mother and fetus, and an informed decision should be made. In this review, we present an up-to-date overview of VTE management in pregnancy and the postpartum period. Keywords: Anticoagulants; Deep venous thrombosis; Pregnancy; Pulmonary embolism; Venous thromboembolism

The development of METAL-WRF Regional Model for the description of dust mineralogy in the atmosphere

The mineralogical composition of airborne dust particles is an important but often neglected parameter for several physiochemical processes, such as atmospheric radiative transfer and ocean biochemistry. We present the development of the METAL-WRF module for the simulation of the composition of desert dust minerals in atmospheric aerosols. The new development is based on the GOCART-AFWA dust module of WRF-Chem. A new wet deposition scheme has been implemented in the dust module alongside the existing dry deposition scheme. The new model includes separate prognostic fields for nine (9) minerals: illite, kaolinite, smectite, calcite, quartz, feldspar, hematite, gypsum, and phosphorus, derived from the GMINER30 database and also iron derived from the FERRUM30 database. Two regional model sensitivity studies are presented for dust events that occurred in August and December 2017, which include a comparison of the model versus elemental dust composition measurements performed in the North Atlantic (at Izaña Observatory, Tenerife Island) and in the eastern Mediterranean (at Agia Marina Xyliatos station, Cyprus Island). The results indicate the important role of dust minerals, as dominant aerosols, for the greater region of North Africa, South Europe, the North Atlantic, and the Middle East, including the dry and wet depositions away from desert sources. Overall, METAL-WRF was found to be capable of reproducing the relative abundances of the different dust minerals in the atmosphere. In particular, the concentration of iron (Fe), which is an important element for ocean biochemistry and solar absorption, was modeled in good agreement with the corresponding measurements at Izaña Observatory (22% overestimation) and at Agia Marina Xyliatos site (4% overestimation). Further model developments, including the implementation of newer surface mineralogical datasets, e.g., from the NASA-EMIT satellite mission, can be implemented in the model to improve its accuracy.This study was supported by the Hellenic Foundation for Research and Innovation project Mineralogy of Dust Emissions and Impacts on Environment and Health (MegDeth - HFRI no. 703). Part of this study was conducted within the framing of the AERO-EXTREME (PID2021-125669NB-I00) project funded by the State Research Agency/Agencia Estatal de Investigación of Spain and the European Regional Development Funds

Synthesis of 2D Germanane (GeH):a New, Fast, and Facile Approach

Germanane (GeH), a germanium analogue of graphane, has recently attracted considerable interest because its remarkable combination of properties makes it an extremely suitable candidate to be used as 2D material for field effect devices, photovoltaics, and photocatalysis. Up to now, the synthesis of GeH has been conducted by substituting Ca by H in a beta-CaGe2 layered Zintl phase through topochemical deintercalation in aqueous HCl. This reaction is generally slow and takes place over 6 to 14 days. The new and facile protocol presented here allows to synthesize GeH at room temperature in a significantly shorter time (a few minutes), which renders this method highly attractive for technological applications. The GeH produced with this method is highly pure and has a band gap (E-g) close to 1.4 eV, a lower value than that reported for germanane synthesized using HCl, which is promising for incorporation of GeH in solar cells

Use of wild bird surveillance, human case data and GIS spatial analysis for predicting spatial distributions of West Nile Virus in Greece

West Nile Virus (WNV) is the causative agent of a vector-borne, zoonotic disease with a worldwide distribution. Recent expansion and introduction of WNV into new areas, including southern Europe, has been associated with severe disease in humans and equids, and has increased concerns regarding the need to prevent and control future WNV outbreaks. Since 2010, 524 confirmed human cases of the disease have been reported in Greece with greater than 10% mortality. Infected mosquitoes, wild birds, equids, and chickens have been detected and associated with human disease. The aim of our study was to establish a monitoring system with wild birds and reported human cases data using Geographical Information System (GIS). Potential distribution of WNV was modelled by combining wild bird serological surveillance data with environmental factors (e.g. elevation, slope, land use, vegetation density, temperature, precipitation indices, and population density). Local factors including areas of low altitude and proximity to water were important predictors of appearance of both human and wild bird cases (Odds Ratio = 1,001 95%CI = 0,723–1,386). Using GIS analysis, the identified risk factors were applied across Greece identifying the northern part of Greece (Macedonia, Thrace) western Greece and a number of Greek islands as being at highest risk of future outbreaks. The results of the analysis were evaluated and confirmed using the 161 reported human cases of the 2012 outbreak predicting correctly (Odds = 130/31 = 4,194 95%CI = 2,841–6,189) and more areas were identified for potential dispersion in the following years. Our approach verified that WNV risk can be modelled in a fast cost-effective way indicating high risk areas where prevention measures should be implemented in order to reduce the disease incidence

Detaillierte numerische Simulationen von flugtriebwerksrelevanten Zweiphasenströmungen

In dieser Arbeit werden numerische Simulationen von Gas-Flüssigkeit-Zweiphasenströmungen unter Berücksichtigung der Phasengrenze zwischen den beteiligten Fluiden durchgeführt, wobei der Fokus auf Prozessen liegt, welche für die Kraftstoffzerstäubung in Flugtriebwerken relevant sind. Die numerische Untersuchung der Phasengrenzendynamik und des Primärzerfalls kann dazu beitragen, das Verständnis der komplexen Vorgänge an der Phasengrenze zu erhöhen und so prädiktiven Zerfallsmodellen einen kleinen Schritt näher zu kommen. Die in dieser Arbeit untersuchten Konfigurationen sind so ausgewählt, dass die verschiedenen Aspekte, die bei der Kraftstoffzerstäubung in Flugtriebwerken eine Rolle spielen, Berücksichtigung finden. Es werden ein schubspannungsgetriebener flüssiger Wandfilm in beschleunigter Luftströmung, der Strahlzerfall eines Kerosinjets in einer senkrecht dazu verlaufenden Luftströmung, und der Zerfall eines flüssigen Wandfilms, welcher am Ende der filmtragenden Wand zwei Luftströmen ausgesetzt ist, numerisch untersucht. Dabei werden die Simulationsergebnisse experimentellen Daten gegenübergestellt und besonderes Augenmerk auf die Beschreibung der Phasengrenzendynamik gelegt, welche bei Primärzerfallsprozessen einer detaillierten experimentellen Untersuchung in der Regel nicht zugänglich ist. Am Beispiel des letztgenannten Falls wird ein Konzept vorgestellt, welchem der Gedanke zugrunde liegt, einen Zerstäubungsvorgang mittels Direkter Numerischer Simulation (DNS)zu berechnen, ohne die detaillierte Geometrie der Zerstäubungsapparatur in der DNS abbilden zu müssen. Dazu wird nur das interessierende Teilgebiet in der DNS abgebildet und die Randbedingungen für die Ränder des gewählten DNS-Gebietes durch separate Simulationen zuvor berechnet. Darüber hinaus wird der Einfluss einzelner Parameter auf das dynamische Verhalten der Phasengrenze isoliert, was experimentell oftmals nicht zu bewerkstelligen ist. Zur numerischen Untersuchung wird ein auf der Volume-of-Fluid-Methode (VoF) basierendes Verfahren zur Erfassung der Phasengrenze eingesetzt. Der Vorteil von VoF-Verfahren liegt darin, dass sie konservativ sind und starke Topologieänderungen der Phasengrenze abbilden können

«Aξιοποίηση μηχανικής μάθησης για τη μελέτη ιατροβιολογικών δεδομένων σχετικών με τον καρκίνο»

Σε μια εποχή που η επιστημονική πληροφορία παράγεται με ραγδαίους ρυθμούς, η ανάγκη της σταχυολόγησης της από ερευνητές του βιοϊατρικού χώρου και κλινικούς ιατρούς γίνεται άκρως σημαντική. Για αυτόν το λόγο, μια από τις μεγαλύτερες σύγχρονες προκλήσεις της Ιατρικής Πληροφορικής και της Βιοπληροφορικής είναι η δημιουργία συστημάτων που να παρέχουν με αυτοματοποιημένο τρόπο, αξιόπιστες απαντήσεις σε ερωτήσεις βιοϊατρικού περιεχομένου, σε πραγματικό χρόνο. Κύριος σκοπός της παρούσας εργασίας είναι η ανάλυση και ταξινόμηση ερωτήσεων ιατρικού-κλινικού περιεχομένου με έμφαση στις ερωτήσεις που αφορούν την Ογκολογία. Η επεξεργασία των ερωτήσεων επιχειρήθηκε με μεθόδους της Μηχανικής Μάθησης και της Επεξεργασίας Φυσικής Γλώσσας με απώτερο σκοπό τη εύρεση των βέλτιστων απαντήσεων σε αυτές σύμφωνα με τους κανόνες της Ιατρικής Βασισμένης σε Στοιχεία. Το σύνολο δεδομένων της παρούσας εργασίας, αντλήθηκε από τη βάση δεδομένων του BioASQ Challenge. To BioASQ Challenge συνίσταται σε ένα παγκόσμιο διαγωνισμό επεξεργασίας επιστημονικών κειμένων και δημιουργίας συστημάτων αυτοματοποιημένης απάντησης στο βιοϊατρικό χώρο. Οι ερωτήσεις χαρακτηρίστηκαν και κατηγοριοποιήθηκαν από δύο ανεξάρτητους ειδικούς, σύμφωνα με κανόνες της Ιατρικής Βασισμένη σε Στοιχεία. Η αλληλουχία της επεξεργασίας των ερωτήσεων διαχωρίστηκε σε τρία στάδια, καθένα από τα οποία εστίασε σε διαφορετικές ιδιότητες των ερωτήσεων. Στο πρώτο, επιχειρήθηκε η αυτόματη ταξινόμηση των ερωτήσεων σε ερωτήσεις τύπου background, δηλαδή σε ερωτήσεις των οποίων η απάντηση είναι γενικής φύσης, ξεκάθαρη και παγιωμένη και σε ερωτήσεις foreground των οποίων η απάντηση αφορά συγκεκριμένες κλινικές περιπτώσεις και/ή αφορά γνώση που δεν έχει ακόμη ξεκάθαρη απάντηση και αποτελεί αντικείμενο αντιπαράθεσης To δεύτερο στάδιο αφορούσε την αυτόματη ανίχνευση της ύπαρξης των στοιχείων PICO (patient, intervention, comparison, outcome) στις ερωτήσεις foreground. To τρίτο και τελευταίο στάδιο περιείχε την κατηγοριοποίηση των ερωτήσεων σε ερωτήσεις που αφορούν τη θεραπεία, τη διάγνωση, την πρόγνωση ασθενειών καθώς και τη συσχέτιση διαφόρων παραγόντων με ασθένειες. Σε αυτό το πλαίσιο, καταφέραμε να χαρακτηρίσουμε και να ταξινομήσουμε με επιτυχία, με συνδυασμό διάφορων μοντέλων Μηχανικής Μάθησης κλινικές ερωτήσεις του BioASQ challenge. Συγκεκριμένα, σε καθένα από τα στάδια κατασκευάσαμε μοντέλα που ταξινόμησαν τις ερωτήσεις σε στατιστικά σημαντικό βαθμό σε σχέση με την τυχαιότητα και αρκετές φορές σε επίπεδα συγκρίσιμα με αυτά της ιδανικής ταξινόμησης. Η απόδοση των μοντέλων θεωρήθηκε σημαντική όταν συγκρίθηκε και με τη συμφωνία ανθρώπων - κριτών στην ταξινόμηση των ερωτήσεων. Η κατηγοριοποίηση των ερωτήσεων με αυτόν τον τρόπο αποσκοπεί στη διευκόλυνση της αναζήτησης των βέλτιστων απαντήσεων στους τύπους κλινικών μελετών που αντιστοιχούν σε κάθε κατηγορία. Φιλοδοξία της παρούσας εργασίας είναι να θέσει τα θεμέλια για τη δημιουργία ενός ολοκληρωμένου συστήματος αυτοματοποιημένης απάντησης βιοϊατρικών ερωτήσεων που να παρέχει απαντήσεις σεβόμενο την ιεράρχηση των στοιχείων της σύγχρονης Ιατρικής Βασισμένης σε Στοιχεία.Living in an era when scientific information is voluminously produced, the need for its critical evaluation is all the more pronounced. For this reason, the construction of tools that provide reliable answers, to biomedical questions, in an automated manner, is one of the greatest modern challenges of Biomedical Informatics. The main target of this work is to analyze and classify questions of medical-clinical content, with emphasis put on the field of Medical Oncology. The questions used as initial data in this Thesis, were processed with various methods of Natural Language Processing and Machine Learning, with the overarching goal of matching them to the best source that may facilitate to their answer, based on rules of Evidence Based Medicine. The dataset of the current Thesis was drawn from the question database of the BioASQ Challenge. The BioASQ Challenge is an international biomedical text analysis competition. The questions included in our dataset were further analyzed and classified by two biomedical experts. The sequence of analysis of the dataset was divided in three stages, each focusing in different ontological aspects of the questions. First, we attempted to automatically classify the set in background questions i.e. questions that have a clear, well defined answer that can be sought into textbooks, and foreground questions i.e. questions that concern specific cases of patients, therapies or diseases and their answer is a subject of controversy, being in the edge of knowledge and should be sought in research repositories (eg Pubmed). The second stage, regarded the automated identification of PICO elements (patient, intervention, comparison, outcome) in the subset of foreground questions. The last step considered the classification of foreground questions to ones of therapy, diagnosis, prognosis and outcome. The main aim of these stages was to identify elements that would point to certain directions as per what type of clinical research evidence would be the best source for answering each question. In this context, we managed to successfully classify the dataset of clinical questions, with a combination of Machine Learning methods. Specifically, in each of the three stages we constructed models that classified questions not only better than a random classifier, but also, in many cases, approached the performance of ideal classification. Our ambition, stemming from this Thesis, is the construction of an automated clinical question answering system that sets the respect of the Evidence Based Medicine rules as its top priority