Σχεδιασμός & πειραματική μελέτη διάταξης «αεροκουρτίνας» για προστασία αμπερομετρικού αισθητήρα ΝΟΧ από επικαθίσεις αιθάλης

104 σ.Η παρούσα διπλωματική εργασία αναφέρεται στο σχεδιασμό και την πειραματική μελέτη μιας διάταξης κουρτίνας αέρα που θα προστατεύει έναν αμπερομετρικό αισθητήρα NOx, αρχικά σχεδιασμένα για εφαρμογές στην αυτοκινητοβιομηχανία, από επικαθίσεις αιθάλης. Ο αισθητήρας θα προστατεύεται μέσω της ροής πεπιεσμένου αέρα όταν δεν καταγράφει μετρήσεις ώστε να είναι μόνιμα εγκατεστημένος στον αγωγό καυσαερίων του κινητήρα. Δοκιμάστηκαν δύο τύποι αυτής της διάταξης που αποτελούνταν από ένα ομοίωμα αισθητήρα και ένα ακροφύσιο αέρα , για διαφορετικές τιμές της πίεσης του αέρα. Ο ρυθμός επικάθισης της αιθάλης αξιολογήθηκε μέσω τεχνικών επεξεργασίας των εικόνων των αισθητήρων, προκειμένου να καθοριστεί η πλέον αποτελεσματική διάταξη. Στη συνέχεια δοκιμάστηκε η τελική διάταξη που αποτελείται από τον πραγματικό αισθητήρα NOx και το επιλεγμένο ακροφύσιο αέρα. Οι μετρήσεις του αισθητήρων συγκρίθηκαν με ταυτόχρονες μετρήσεις από αναλυτή τύπου χημικής φωταύγειας, που πιστοποιείται από το Διεθνή Ναυτιλιακό Οργανισμό. Επιπλέον, οι μετρήσεις NOx από τον αισθητήρα καταγράφηκαν με τη συσκευή κουρτίνας αέρα σε λειτουργία, προκειμένου να διερευνηθούν οι επιπτώσεις της λειτουργίας της διάταξης στην ακρίβεια των μετρήσεων του αισθητήρα.This thesis refers to the design and experimental study of an air curtain arrangement that would protect an amperometric NOX sensor, initially designed for automotive applications, from excessive soot loading. The sensor is purposed to be permanently installed in the engine exhaust duct and it would be protected by the air curtain flow when it does not record measurements. Two types of this arrangement which consisted of a dummy sensor and an air nozzle were tested, for different values of air pressure. The amount of soot deposition was evaluated through processing techniques of dummy sensors’ images, in order to define the most effective arrangement. The final structure which consists of the actual NOX sensor and the selected air nozzle was tested. The sensor readings were compared to simultaneous measurements of a CLD type analyzer, specified by IMO. Moreover, NOX measurements by the sensor were recorded with the air curtain device switched on, in order to investigate the impact of the arrangement’s operation on the sensor’s output.Λάμπρος Δ. Ρίζο

Expected spectral characteristics of (101955) Bennu and (162173) Ryugu, targets of the OSIRIS-REx and Hayabusa2 missions

NASA's OSIRIS-REx and JAXA's Hayabusa2 sample-return missions are currently on their way to encounter primitive near-Earth asteroids (101955) Bennu and (162173) Ryugu, respectively. Spectral and dynamical evidence indicates that these near-Earth asteroids originated in the inner part of the main belt. There are several primitive collisional families in this region, and both these asteroids are most likely to have originated in the Polana-Eulalia family complex. We present the expected spectral characteristics of both targets based on our studies of our primitive collisional families in the inner belt: Polana-Eulalia, Erigone, Sulamitis, and Clarissa. Observations were obtained in the framework of our PRIMitive Asteroids Spectroscopic Survey (PRIMASS). Our results are especially relevant to the planning and interpretation of in-situ images and spectra to be obtained by the two spacecraft during the encounters with their targets.Comment: 22 pages, 11 figures. Accepted for publication in Icarus on May 11, 201

Soluble form of ICAM-1, VCAM-1, E- and L-selectin in human milk.

In breast milk and paired serum from 70 lactating women and 40 of their term, infection-free neonates, on the 2nd and 5th day postpartum slCAM-1, sVCAM-1, sE- and sL-selectin were measured by ELISA and compared with those in 26 healthy adults (controls). Seven infant formulas and fresh milk from five cows were also analyzed. Human colostrum values of slCAM-1, sVCAM-1 (similar to those in maternal and control serum), sE-selectin and sL-selectin (-10 and -100 times lower than in maternal and control serum) were significantly higher than those in milk, while they varied widely. None of the adhesion molecules was detected in fresh cow's milk or infant formulas. Exclusively breast-fed infants showed significantly higher values of slCAM-1 and sL-selectin on the 2nd day of life than those supplemented also with formula. Only slCAM-1 values correlated positively between colostrum and time-matched maternal serum. These findings show in human milk important amounts of slCAM-1 and sVCAM-1 but minimal amounts of sE- and sL-selectin, which could affect the immune system of the neonate

Gauge Unification and Quark Masses in a Pati-Salam Model from Branes

We investigate the phase space of parameters in the Pati-Salam model derived in the context of D-branes scenarios, requiring low energy string scale. We find that a non-supersymmetric version complies with a string scale as low as 10 TeV, while in the supersymmetric version the string scale raises up to ~2 x 10^7 TeV. The limited energy region for RGE running demands a large tan(beta) in order to have experimentally acceptable masses for the top and bottom quarks.Comment: 11 pages, LaTeX, 7 figures include

Role of the oviduct and oviduct-derived products in ruminant embryo development

Abstract The fact that embryos can be obtained in vitro undermines the role of the oviduct. However, it has been demonstrated that when in vitro produced bovine zygotes are cultured in the oviduct of sheep, cattle or mice the embryo quality is improved compared to the embryos produced in vitro. Thus the oviduct is not simply a passive organ required only for transporting the embryo to the uterus but also provides a suitable microenvironment for the early embryo. The study of physiological mechanisms and interactions between the embryo and the oviductal environment is essential to understand the correct processes of early embryo developmental. This knowledge can be used to improve current in vitro procedures providing high quality embryos capable of continued development and implantation, and resulting in viable births

Sexually dimorphic gene expression in bovine conceptuses at the initiation of implantation

In cattle, maternal recognition of pregnancy occurs on Day 16 via secretion of interferon tau (IFNT) by the conceptus. The endometrium can distinguish between embryos with different developmental competencies. In eutherian mammals, X-chromosome inactivation (XCI) is required to ensure an equal transcriptional level of most X-linked genes for both male and female embryos in adult tissues, but this process is markedly different in cattle than mice. We examined how sexual dimorphism affected conceptus transcript abundance and amino acid composition as well as the endometrial transcriptome during the peri-implantation period of pregnancy. Of the 5132 genes that were differentially expressed on Day 19 in male compared to female conceptuses, 2.7% were located on the X-chromosome. Concentrations of specific amino acids were higher in the uterine luminal fluid of male compared to female conceptuses, while female conceptuses had higher transcript abundance of specific amino acid transporters (SLC6A19 and SLC1A35). Of note, the endometrial transcriptome was not different in cattle gestating a male or a female conceptus. These data support the hypothesis that, far from being a blastocyst specific phenomenon, XCI is incomplete before and during implantation in cattle. Despite differences in transcript abundance and amino acid utilization in male versus female conceptuses, the sex of the conceptus itself does not elicit a different transcriptomic response in the endometrium

Inflammatory cytokines in newborn infants.

Serum levels of IL-1beta, IL-6 and TNF-alpha were measured in 48 healthy, termed neonates on the 1st (N1), 5th (N5) and 40th (N40) day after birth, compared with those in maternal serum (MS), umbilical cord (UC) and adult controls. Cytokine values in N1 and N5 were significantly elevated, than those in UC and in controls (P<0.0001). IL-1beta and IL-6 declined significantly from N1 to N40 (P<0.0001), while TNF-alpha increased significantly from N1 to N5 and declined thereafter. MS infinity IL-1beta and IL-6, but not MS infinity TNF-alpha, were significantly higher than those of controls (P<0.0001). IL-1beta values depended on the mode of delivery. In conclusion, the increased concentrations of IL-1beta, IL-6 and TNF-alpha during the perinatal period might suggest their involvement in an inflammation-like process during normal parturition, and reflect also a newborn immune response to the stress of delivery and environmental changes

Medication Regimen Complexity and Readmissions after Hospitalization for Heart Failure, Acute Myocardial Infarction, Pneumonia, and Chronic Obstructive Pulmonary Disease

Objectives: Readmission rate is increasingly being viewed as a key indicator of health system performance. Medication regimen complexity index scores may be predictive of readmissions; however, few studies have examined this potential association. The primary objective of this study was to determine whether medication regimen complexity index is associated with all-cause 30-day readmission after admission for heart failure, acute myocardial infarction, pneumonia, or chronic obstructive pulmonary disease. Methods: This study was an institutional review board–approved, multi-center, case–control study. Patients admitted with a primary diagnosis of heart failure, acute myocardial infarction, pneumonia, or chronic obstructive pulmonary disease were randomly selected for inclusion. Patients were excluded if they discharged against medical advice or expired during their index visit. Block randomization was utilized for equal representation of index diagnosis and site. Discharge medication regimen complexity index scores were compared between subjects with readmission versus those without. Medication regimen complexity index score was then used as a predictor in logistic regression modeling for readmission. Results: Seven hundred and fifty-six patients were randomly selected for inclusion, and 101 (13.4%) readmitted within 30days. The readmission group had higher medication regimen complexity index scores than the no-readmission group (p\u3c0.01). However, after controlling for demographics, disease state, length of stay, site, and medication count, medication regimen complexity index was no longer a significant predictor of readmission (odds ratio 0.99, 95% confidence interval 0.97–1.01) or revisit (odds ratio 0.99, 95% confidence interval 0.98–1.02). Conclusion: There is little evidence to support the use of medication regimen complexity index in readmission prediction when other measures are available. Medication regimen complexity index may lack sufficient sensitivity to capture an effect of medication regimen complexity on all-cause readmission

Self-optimizing block transfer in web service grids

Nowadays, Web Services (WSs) play an increasingly impor-tant role in Web data management solutions, since they offer a practical solution for accessing and manipulating data sources spanning administrative domains. Neverthe-less, they are notoriously slow and transferring large data volumes across WSs becomes the main bottleneck in such WS-based applications. This paper deals with the problem of minimizing at runtime, in a self-managing way, the data transfer cost of a WS encapsulating a data source. To reduce the transfer cost, the data volume is typically divided into blocks. In this case, response time exhibits a quadratic-like, non-linear behavior with regards to the block size; as such, minimizing the transfer cost entails finding the optimum block size. This situation is encountered in several systems