2,963 research outputs found
<b>Optical filter at 0.68/0.75 µm based on photonic crystal fiber and Au</b><b> </b><b>surface plasmon resonance</b>
No full textThese figures were done by Younis M. Atiah.</p
The ethics of academic research and writing / Luay Thanoon Younis
No full textPlagiarism is an act or instance of using or closely imitating the language and thoughts of another author without authorization and the representation of that author's work as one's own without appropriately crediting the original author. This misconduct could be committed recklessly, knowingly, or intentionally
La straniera di Younis Tawfik: un dialogo tra due culture
No full textIn 1999 the Iraqi migrant writer Younis Tawfik was awarded several literary prizes for his novel La straniera, written in Italian and published by Bompiani. In this essay I will discuss some aspects of the novel that might have contribuited to its success. After a short presentation of the author and of the content of the novel, I will analyse La straniera, in order to show the novelty of its structure. Furthermore, I will expalin how this hybrid work reveals the double culture of the author from a literary and linguistic point of view. I will also consider how the author contributed to the current debate on migration, by examining his treatment of some themes related to this phenomenon
An Approach for Supporting Software Partitioning and Reuse in Integrated Modular Avionics
No full textCorrigendum: Performance evaluation of five commercial assays in assessing seroprevalence of HEV antibodies among blood donors
No full textThe affiliation for author Lukman Thalib was incorrectly listed as number 5. It should have been listed as number 3. Please see corrected author and affiliation list below:
Enas S. Al-Absi,1,2 Duaa W. Al- Sadeq,1 Manaf H. Younis,3 Hadi M. Yassine,2 Omnya M. Abdalla,1 Areej G. Mesleh,1 Tameem A. Hadwan,1 Joshua O. Amimo,4,5 Lukman Thalib,3 and Gheyath K. Nasrallah1,2,*
1 Department of Biomedical Science, College of Health Sciences, Qatar University, Doha, Qatar
2 Biomedical Research Center, Qatar University, Doha, Qatar
3 Department of Public Health, College of Health Sciences, Qatar University, Doha, Qatar
4 Department of Animal Production, Faculty of Veterinary Medicine University of Nairobi, Nairobi, Kenya
5 Biosciences of Eastern and Central Africa-International Livestock Research Institute (BecA-ILRI), Nairobi, Kenya
The authors apologize for any inconvenience caused.
© 2019 The AuthorsNo Full Tex
Study of internal jugular vein valve mechanism function: post analysis of M- mode imaging and an experimental model under cardiac monitoring.
No full textBackground:
Traditionally, the internal jugular vein (IJV) has served as an indicator of right side cardiac function via measurement of central venous pressure and changes in the velocity of jugular venous flow. Since the internal jugular vein valve is the only protective vessel between the brain and heart, recent studies have focused on the dynamic behavior of the valve and its importance in regulating the cerebral blood out flow pathway. It is found that the function of the IJV valve is crucial in maintaining the transcranial blood pressure gradient during cardiopulmonary resuscitation with closed-chest while the morphological incompetence (or absence) of the valve may lead to venous reflux through the IJV. However, nothing is known about the mechanism of the valve opening and closure, as well as the normal opening time. Furthermore, there is insufficient knowledge whether the venous reflux is a normal finding and it is not associated with valve incompetence or valve absence.
Aim of the study:
The project aims to add new indicators of internal Jugular valve function through: 1) post imaging analysis using ultrasound M mode image and 2) an experimental model of mimicking fluid loop to study the modality of flow and pressure wave, upstream and downstream in internal jugular vein with or without valve build up.
Methods:
Normal young subjects underwent an ultrasound scan of the neck in supine position. The internal jugular vein valve was evaluated using B-mode and M-mode images. Two methods have been demonstrated to deduce the normal open time of the valve. The first method based on calculating the area under the curve of valve leaflet separation distance ratio per cardiac cycle. The second method is based on logical tests of three thresholds to examine the valve leaflet separation distance ratio. A hydraulic mimicking fluid loop is created using a programmable pump (Compu Flow 1000, Shelley Medical Imaging/London/Canada). The flow-loop model represents the cerebral out flow pathway through internal Jugular phantoms with and without valve build up. The measurements of flow and pressure were taking at two positions upstream and downstream of the phantom.
Results:
The first method concerning the normal open time reveals a strong positive correlation with second method at the threshold 0.5. The open time of IJV valve constitutes 70% of the cardiac cycle. The experimental model yields a different modality of flow and pressure upstream and downstream of phantoms. A back flow occurs in the beginning of the pulsatile flow wave at a downstream position. The difference in pressure between the two positions increases with the mean flow rate and decreases with higher flow rate in the phantom with no valve while in phantom with valve, the pressure difference has mostly linear proportion with the flow rate.
Conclusions:
The normal open time of the internal jugular vein valve is a new physiologic metric and it gives premise for further studies in the field of neurodegeneration. The experimental finding is adding a new concept to the venous reflux in the internal jugular vein and the necessity of the valve presence in maintain an adequate pressure difference through IJV.Introduzione:
Lo studio emodinamico della vena giugulare interna (IJV) fornisce indicazioni sulla funzionalità cardiaca. La vena giugulare interna è dotata di una valvola che ha una funzione protettiva, studi recenti si sono concentrati sul comportamento dinamico della valvola e sulla sua importanza nella regolazione del flusso ematico cerebrale. Questi studi hanno mostrato che questa valvola ha la funzione di regolare il gradiente della pressione nell’asse cervello – cuore. L’assenza o l'incompetenza funzionale della valvola può anche portare al fenomeno del reflusso venoso attraverso la IJV. Tuttavia, il meccanismo dell'apertura e della chiusura della valvola non è stato ancora studiato a fondo, in particolare non sono si hanno informazioni sul suo ritmo di apertura e chiusura. Inoltre, non vi sono conoscenze sufficienti per capire se il fenomeno del reflusso venoso sia normale o possa essere associato a incompetenza della valvola e quindi indicatore di possibili stati patologici.
Obiettivo dello studio:
Il progetto mira ad individuare nuovi indicatori della funzione della valvola giugulare interna attraverso: 1) Studio delle immagini ecografiche della valvola acquisite in M mode; 2) Utilizzo di circuito fluidodinamico sperimentale per lo studio della relazione tra impulso pressorio a monte e a valle della vena giugulare ed il suo flusso in presenza ed assenza della valvola interna.
Metodi:
Un gruppo soggetti normali sono stati sottoposti ad ecografia del collo in posizione supina. La valvola vena giugulare interna è stata studiata usando le immagini acquisite sia B-mode che M-mode. Sono stati utilizzati due metodi per ricavare informazioni sui tempi di apertura e di chiusura della valvola. Il primo metodo è basato sul calcolo dell'area sottesa dalla curva che rappresenta la distanza di separazione del lembo della valvola per un intero ciclo cardiaco. Il secondo metodo vuole introdurre test logici utilizzando tre soglie di riferimento per studiare la distanza di separazione delle alette della valvola. E’ stato realizzato un circuito idraulico che imita la fluidodinamica del tratto Ventricolo – Cervello – Atrio utilizzando una pompa programmabile (Compu Flow 1000, Shelley Medical Imaging / London / Canada) che immette un fluido in un circuito ad anello avente segmenti che possono simulare la vena Giugulare con e senza valvola
Risultati:
Il primo metodo di studio del tempo apertura ha una buona correlazione positiva con metodo logico quando si utilizza il parametro di soglia soglia 0,5. Il tempo di apertura della valvola IJV è circa il 70% della durata di ogni ciclo cardiaco. Il modello sperimentale fornisce risultati specifici per le due diverse misure di flusso e pressione (a monte e a valle) dei fantocci. Il fenomeno del reflusso si verifica all'inizio dell'onda di flusso pulsatile in una posizione a valle per il flussi più alti. La differenza di pressione tra le due posizioni aumenta con la portata media e diminuisce crescere della portata nel fantoccio senza valvola mentre nell’altro (con valvola), la differenza di pressione ha un andamento lineare con la portata.
Conclusioni:
Il tempo di apertura della valvola vena giugulare interna rappresenta una nuova metrica fisiologica che può essere utilizzata per ulteriori studi più approfonditi nel campo della insufficienze del ritorno venoso cerebrale. Il modello sperimentale ha aggiunto di un nuove informazioni sulla comparsa del al reflusso venoso nei simulatori della vena giugulare interna e sulla funzione della della valvola nel mantenere un'adeguata gradiente pressorio nella IJV
Robust Approach for Supporting Inter-Application Communication and Device Handling in Integrated Modular Avionics
No full textAn Efficient Reduced-Order Model to Investigate the Behavior of an Imperfect Microbeam Under Axial Load and Electric Excitation
No full textThree-Phase Modular Multilevel Converter (MMC) for Low-voltage Applications: Improved Modulation Technique Toward Less Capacitance Requirement
No full textModular Multilevel Converter (MMC) has become one of the promising topologies in medium and high power applications. Modularity, scalability, and reliability are the main features that give the MMC some advantages over other multilevel topologies when considering high number of levels. This paper presents an alternative modulation technique for a modified modular multilevel converter (M-MMC) topology for low-voltage applications. By using level-shifted carrier (LSC) modulation and the proposed sorting algorithm, the capacitance requirement for this topology can be reduced. Finally, the proposed modulation scheme and the reduction of capacitance are verified by simulation results using PLECS
Three-Phase Multilevel Inverters for LV Systems: Comparison of Modular Multilevel Converter and Flying Capacitor Structures
No full textThe rapid growth of the penetration level of renewable energy sources in low-voltage (LV) networks increases the research interest in more efficient, compact, reliable, and easily expandable energy conversion devices. Thus, multilevel converters, a promising concept for dc-ac conversion, are gaining increased interest due to their smaller size relative to the conventional two-level structure. However, several issues related to the number of components and the added complexity cannot be ignored. To enrich the literature review concerning this topic, this work reviews and provides a comparative assessment of three state-of-the-art multilevel topologies for LV applications. This review considered three structures: state-of-the-art five-level modified MMC (5L-M-MMC), five-level flying capacitor using two three-level flying capacitor converters connected in parallel (2x3L-FC), and five-level flying capacitor (5L-FC). This comparative study is supported by simulation results based on a 10 kW system
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