Deep optical study of the mixed-morphology supernova remnant G 132.7+1.3 (HB3)

We present optical CCD images of the large supernova remnant (SNR) G 132.7+1.3 (HB3) covering its full extent for the first time, in the emission lines of Hα +[N II], [S II], and [O III], where new and known filamentary and diffuse structures are detected. These observations are supplemented by new low-resolution long-slit spectra and higher resolution images in the same emission lines. Both the flux-calibrated images and spectra confirm that the optical emission originates from shock-heated gas since the [S II]/Hα > 0.4. Our findings are also consistent with the recently developed emission-line ratio diagnostics for distinguishing SNRs from H II regions. A multiwavelength comparison among our optical data and relevant observations in radio, X-rays, gamma-rays and CO bands, provided additional evidence on the interaction of HB3 with the surrounding clouds and clarified the borders of the SNR and the adjacent cloud. We discuss the supernova (SN) properties and evolution that led to the current observables of HB3 and we show that the remnant has most likely passed at the pressure driven snowplow phase. The estimated SN energy was found to be (3.7 ± 1.5) × 1051 erg and the current SNR age (5.1 ± 2.1) × 104 yr. We present an alternative scenario according to which the SNR evolved in the wind bubble cavity excavated by the progenitor star and currently is interacting with its density walls. We show that the overall mixed morphology properties of HB3 can be explained if the SN resulted by a Wolf−Rayet progenitor star with mass ∼34 M⊙⁠

Perioperative blood transfusion is associated with a gene transcription profile characteristic of immunosuppression: a prospective cohort study

INTRODUCTION Blood transfusion in the perioperative period has frequently been associated with an excess of nosocomial infections. Whilst transfused whole blood induces specific host immune alteration that may predispose to nosocomial infections, the immunomodulating properties associated with leukodepleted blood remain incompletely understood. In this study, we explore the hypothesis that the transfusion of leukodepleted allogeneic blood during or following major gastrointestinal surgery is associated with an immunosuppressed phenotype, which may in turn predispose to postoperative infectious complications. METHODS Patients aged over 45 years undergoing scheduled inpatient major gastrointestinal surgery were recruited. Gene expression profiles of specific inflammatory genes were assayed from blood collected preoperatively, at 24 and at 48 hours after surgery. Genes were selected based on their ability to represent specific immune pathways. Gene expression was quantified using quantitative real-time polymerase chain reaction (qRT-PCR) to measure messenger RNA (mRNA) levels. Postoperative infections were documented using predefined criteria. RESULTS One hundred and nineteen patients were recruited. Fifteen (13%) patients required blood transfusion within 24 hours of surgery, 44 (37%) patients developed infections and 3 (2%) patients died prior to discharge. Patients receiving a blood transfusion were more likely to develop postoperative infections (P =0.02) and to have lower tumour necrosis factor alpha (TNFα), interleukin (IL)-12, IL-23 and RAR-related orphan receptor gamma T (RORγt) gene expression in the postoperative period (P <0.05). The TNFα/IL-10 mRNA ratio at 24 hours (P =0.0006) and at 48 hours (P =0.01) was lower in patients receiving a blood transfusion over this period. Multivariable analysis confirmed that these observations were independent of the severity of the surgical insult. CONCLUSIONS An association between an immunosuppressive pattern of gene expression and blood transfusion following major elective gastrointestinal surgery is described. This gene expression profile includes a reduction in the activity of innate immunity and T helper cell type 1 (Th1) and T helper cell type 17 (Th17) pathways in those patients receiving a blood transfusion. Blood transfusion was also associated with an excess of infectious complications in this cohort. A mechanistic link is suggested but not proven

Risk of stroke in hospitalized SARS-CoV-2 infected patients: A multinational study

Background: There is an increased attention to stroke following SARS-CoV-2. The goal of this study was to better depict the short-term risk of stroke and its associated factors among SARS-CoV-2 hospitalized patients. Methods: This multicentre, multinational observational study includes hospitalized SARS-CoV-2 patients from North and South America (United States, Canada, and Brazil), Europe (Greece, Italy, Finland, and Turkey), Asia (Lebanon, Iran, and India), and Oceania (New Zealand). The outcome was the risk of subsequent stroke. Centres were included by non-probability sampling. The counts and clinical characteristics including laboratory findings and imaging of the patients with and without a subsequent stroke were recorded according to a predefined protocol. Quality, risk of bias, and heterogeneity assessments were conducted according to ROBINS-E and Cochrane Q-test. The risk of subsequent stroke was estimated through meta-analyses with random effect models. Bivariate logistic regression was used to determine the parameters with predictive outcome value. The study was reported according to the STROBE, MOOSE, and EQUATOR guidelines. Findings: We received data from 26,175 hospitalized SARS-CoV-2 patients from 99 tertiary centres in 65 regions of 11 countries until May 1st, 2020. A total of 17,799 patients were included in meta-analyses. Among them, 156(0.9) patients had a stroke�123(79) ischaemic stroke, 27(17) intracerebral/subarachnoid hemorrhage, and 6(4) cerebral sinus thrombosis. Subsequent stroke risks calculated with meta-analyses, under low to moderate heterogeneity, were 0.5 among all centres in all countries, and 0.7 among countries with higher health expenditures. The need for mechanical ventilation (OR: 1.9, 95 CI:1.1�3.5, p = 0.03) and the presence of ischaemic heart disease (OR: 2.5, 95 CI:1.4�4.7, p = 0.006) were predictive of stroke. Interpretation: The results of this multi-national study on hospitalized patients with SARS-CoV-2 infection indicated an overall stroke risk of 0.5(pooled risk: 0.9). The need for mechanical ventilation and the history of ischaemic heart disease are the independent predictors of stroke among SARS-CoV-2 patients. Funding: None. © 2020 The Author

INFLUENCE OF DRYING CONDITIONS AND MATHEMATICAL MODELS ON THE THIN LAYER DRYING OF MUSHROOMS

ABSTRACT In the present research, experimental data from several studies about drying behavior of mushrooms have been selected and used to compare different drying methods and different mathematical thin layer drying models to simulate mushroom drying rates. The white button (Agaricus Bisporus), the oyster (Pleurotus Ostreatus) and the milky mushroom slices have been considered for drying in different dryers such as hot air cabinet dryer and fluidized bed dryer with different slice thicknesses, drying air temperatures (45 °C to 90 °C) and drying air velocities (0.2 m/s to 5 m/s). The entire drying process has taken place in the falling rate period, assuming that internal mass transfer occurred by diffusion in mushroom slices. The study shows that the drying air temperature and the drying air velocity have an effect on the moisture removal from mushrooms and also on the drying time. Mathematical models have been proved to be useful for design and analysis of heat and mass transfer during drying processes. All the drying models considered in this study could adequately represent the thin layer drying behavior of mushrooms. Furthermore, as it is obvious, any type of mushrooms has its own most suitable model

Low Power EEG Data Encoding for Brain Neurostimulation Implants

Neurostimulation devices applied for the treatment of epilepsy that collect, encode, temporarily store, and transfer electroencephalographic (EEG) signals recorded intracranially from epileptic patients, suffer from short battery life spans. The principal goal of this study is to implement strategies for low power consumption rates during the device’s smooth and uninterrupted operation as well as during data transmission. Our approach is organised in three basic levels. The first level regards the initial modelling and creation of the template for the following two stages. The second level regards the development of code for programming integrated circuits and simulation. The third and final stage regards the transmitter’s implementation at the evaluation level. In particular, more than one software and device are involved in this phase, in order to achieve realistic performance. Our research aims to evolve such technologies so that they can transmit wireless data with simultaneous energy efficiency. © 2022 by the authors. Licensee MDPI, Basel, Switzerland

Numerical flow study of non newtonian fluids in an axisymmetric tube dilatation

172 σ.Έγινε η διεξαγωγή υπολογιστικής μελέτης πάνω στη μόνιμη ροή του αίματος, όταν αυτό ρέει σε αγωγό με διεύρυνση, από βιοϊατρικής πλευράς σε αρτηρία με ανεύρυσμα. Μελετήθηκαν τέσσερα μοντέλα ρευστών, που συνήθως χρησιμοποιούνται για την περιγραφή των μη νευτώνειων χαρακτηριστικών του αίματος, τα Walburn-Schneck (W-S), Herschel-Bulkley (H-B), Casson και Quemada. Σε διδιάστατους, αξονικά, συμμετρικούς αγωγούς, αναπτύχθηκαν τρία διαφορετικά είδη υπολογιστικών πλεγματων, η επίλυση των οποίων έγινε με το λογισμικό υπολογιστικής ρευστομηχανικής, FLUENT. Δώσαμε έμφαση στη γεωμετρία του αγωγού, γι’ αυτό και χρησιμοποιήθηκαν δύο διαφορετικοί διευρυμένοι αγωγοί, καθώς και στη δομή του πλέγματός μας, το οποίο ήταν μη δομημένο στην περιοχή της διεύρυνσης του αγωγού. Το εύρος των αριθμών Re που μελετήσαμε περιλάμβανε, τόσο τους χαμηλούς, όσο και υψηλότερους, δηλαδή η μελέτη έγινε για την περιοχή από Re=25 μέχρι Re=600. Το μήκος που απαιτούσαν τα μοντέλα Casson και Quemada για να διαμορφωθεί πλήρως η ροή τους, ήταν κατά πολύ μικρότερο από αυτό των W-S και Η-Β. Διαπιστώσαμε την επίδραση του αριθμού Bi, στο μοντέλο H-B, πάνω στο μήκος διαμόρφωσης όταν αυτός λαμβάνει υψηλές τιμές, δηλαδή σε χαμηλούς Re, αντίστοιχα. Για το νευτώνειο, με την αύξηση του Re, οι τιμές του μήκους διαμόρφωσης αποκλίνουν από τις θεωρητικές τιμές, με τις οποίες σχεδόν ταυτίζονται για πιο χαμηλούς Re. Στο διευρυμένο αγωγό, όταν υπάρχει οξεία συνένωση της κοιλότητας του ανευρύσματος με τον ευθύγραμμο αγωγό, η ροή αποκολλάται πιο γρήγορα. Η ζώνη ανακυκλοφορίας αυξάνεται με τον αριθμό Re και η γραμμή επανακόλλησης μετατοπίζεται προς την έξοδο του μοντέλου, δηλαδή κατάντι. Οι διατμητικές τάσεις παρουσιάζουν τοπικό μέγιστο κοντά στην έξοδο της διεύρυνσης, εξαρτώμενο από τον Re, το οποίο στην περίπτωση του αγωγού με καμπυλότητα είναι πιο χαμηλό και η διατμητική τοιχωματική τάση αυξάνεται πιο ομαλά μέχρι αυτή την τιμή. Επιπλέον, στην έξοδο του μοντέλου χωρίς καμπυλότητα η κατανομή της ταχύτητας παρουσιάζει μια ασυνέχεια σε μικρή απόσταση από το τοίχωμα, η οποία αποδίδεται στην τοπική επιτάχυνση του ρευστού στην οξεία συνένωση 164 του τοιχώματος του ανευρύσματος με τον κυλινδρικό αγωγό. Κάτι τέτοιο δεν παρατηρείται τόσο έντονα όταν ο αγωγός μας έχει καμπυλότητα. Παρατηρήθηκαν μεγάλες διαφορές στον ελάχιστο απαιτούμενο Re για αποκόλληση της ροής για κάθε μη νευτώνειο μοντέλο ρευστού, με κάποια από αυτά να μην έχουν αποκολλήθεί μέχρι και για Re=300, όπως το Quemada. Το ρευστό Quemada παρουσιάζει διαφορετική κλίση διατμητικών τοιχωματικών τάσεων από τα υπόλοιπα ρευστά και δεν εμφανίζει τις υψηλές αρνητικές τιμές που εμφανίζουν τα υπόλοιπα ρευστά. Κατάντι της γραμμής επανακόλλησης, η πίεση ελαττώνεται απότομα και εν συνεχεία μειώνεται γραμμικά ως την έξοδο του ευθύγραμμου κυλινδρικού αγωγού, όπως είναι αναμενόμενο.We conducted a numerical study about the steady blood flow, when it flows within an axisymmetric tube dialatation. The study involved four of the most commonly used models to describe blood’s non-newtonian characteristics, namely: Walburn-Schneck (W-S), Herschel-Bulkley (H-B), Casson and Quemada. In 2-D, axisymmetric, straight and enlarged tubes were developed three different types of numerical grids, which were solved using the commercial numerical code FLUENT. Firstly, we focused on the geometry of the tube, using two different enlarged tubes and secondly on the structure of our grid, which was unstructured in the area of the tube dilatation. We studied the range of Re numbers 25-600, including both the low as the higher numbers. The entrance length for Casson and Quemada was found much less than those of W-S and H-B models. We found the effect of Bi number, in H-B model, on the entrance length, when Bi takes high values and Re low, respectively, extremely important. For the Newtonian model, the values of the entrance length deviate from the theoretical ones, as Re increases. In the enlarged tube, when there is a sharp junction of the model to the exit straight tube, the flow deatachment happens earlier. The recirculation zone increases with Re and the flow reattachment line displaced towards the exit of the model. Wall shear stresses show high peaks at the distal end of the dilatation, depending on the Re, which in the case of the tube with curvature is lower and the increase of the value of WSS is smooth enough, up to thiw value. In addition, at the model exit the velocity profile exhibits a discontuinity a small distance from the wall attributed to local fluid acceleration at the sharp junction of the model to the exit straight tube. We don’t notice it, in such degree, in the case of tube with curvature. Great differences among models were observed in the minimum required Re for the flow deatachment. Quemada model shows different gradient of wall shear stresses and it doesn’t show the high negative peaks as the other models. Downstream of the reattachment line pressure drops abruptly and then it is reduced linearly in the exit straight tube, as expected.Δήμητρα Β. Φράγκο

Low-Power Electroencephalographic Data Encoding System for Implantable Brain Stimulation Systems

This paper studies the Delta encoding scheme and its effect on power dissipation, for wireless transmission from implantable devices. The study was performed on data from electroencephalographic signals. For the implementation of the proposed system, the design approach followed three phases. The first design phase is related to the initial modelling. The second phase included the development of the hardware description code for the proposed system. The third and last phase is related to the evaluation of the transmitted signal and the measurement of the power dissipation. The results showed that up to 23% power savings are possible for a negligible power penalty due to the delta encoding process. © 2021 IEE