Spelling suggestions: "subject:"ionic""
81 |
Etude des effets des rayonnements ionisants sur la niche hématopoïétique et traitement du syndrome aigu d'irradiation par thérapie génique chez le macaque irradié à forte dose / Effects of ionizing radiation on the hematopoietic niche and treatment of acute radiation syndrome by gene therapy in higly-irradiated monkeys.Garrigou, Philippe 07 September 2011 (has links)
La niche des cellules souches hématopoïétiques représente un compartiment complexe et radiosensible. Sa protection est nécessaire pour la restauration de l'hématopoïèse faisant suite à la myélosuppression due à l'exposition aux rayonnements ionisants. Nous avons dans un premier temps étudié l'effet des RI sur les progéniteurs endothéliaux et mésenchymateux de la niche par une étude de radiosensiblilité et une étude d'évaluation de la mort cellulaire. Nous avons proposé par la suite une stratégie innovante de thérapie génique basée sur la sécrétion locale et à court terme du morphogène Sonic hedgehog visant à favoriser la réparation de niche vasculaire et de stimuler les cellules souches hématopoïétiques et les cellules progénitrices résiduelles. Nous avons étudié la réponse hématopoïétique des singes irradiés à 8-Gy gamma après une seule injection intra-osseuse de cellules souches mésenchymateuses xénogéniques, multipotentes et d'origine adipocytaire transfectées avec un plasmide pIRES2-eGFP codant la protéine Shh. La durée de thrombocytopénie et celle de neutropénie ont été significativement réduites chez les animaux greffés et les clonogènes sont normalisés à partir du 42e jour. Les aires sous la courbe des numération des plaquettes et des neutrophiles entre 0 et 30 jours ont été significativement plus élevée chez les animaux traités que chez les témoins. La greffe d'explants de MatrigelTM colonisés ou non avec des ASC chez des souris immunodéprimées a démontré une activité pro-angiogénique notable des ASC transfectées avec le plasmide Shh . Le suivi à long terme (180 à 300 jours) a confirmé une reconstitution durable dans les quatre singes greffés. Globalement cette étude suggère que la greffe de cellules souches multipotentes Shh-peut représenter une nouvelle stratégie pour la prise en charge des dommages radio-induits de la niche. / The hematopoietic stem cell niche represents a complex radiosensitive compartment whose protection is required for recovery from radiation-induced myelosuppression. We initially studied RI effects on endothelial and mesenchymal progenitors by an evaluating radiosensitivity and cell death. Then, we have proposed a new gene therapy strategy based on local and short term secretion of Sonic hedgehog morphogene to favour vascular niche repair and to stimulate residual hematopoietic stem and progenitor cells. We investigated the hematopoietic response of 8-Gy gamma irradiated monkeys to a single intra-osseous injection of xenogeneic multipotent mesenchymal stem cells transduced with a Shh pIRES2 plasmid. Thrombocytopenia and neutropenia duration were significantly reduced in grafted animals and clonogenics normalized from day 42. Areas under the curve of PLTs and ANCs between day 0 and day 30 were significantly higher in treated animals than in controls. Grafting MatrigelTM colonized or not with ASC in immunocompromized mice demonstrated a notable pro-angiogenic activity for Shh-ASC. Long term follow up (180-300 days) confirmed a durable recovery in the four grafted monkeys. Globally this study suggests that grafting Shh-multipotent stem cells may represent a new strategy to cure radiation-induced niche damage.
|
82 |
Vi kan inte blunda för öronen längre : En fallstudie om ljud som kommunikationsmedium i utställningen Drömmens systerCarleklev, Jan January 2008 (has links)
Ljudet är ett intressant kommunikationsmedium som utnyttjar varje individs egna erfarenheter och föreställningar där associationer får stort utrymme. Mu- seer som idag kan välja från ett stort urval av medier har mycket att vinna ge- nom att använda sig av ljud - inte enbart för att tekniken tillåter det. Den här uppsatsen har för avsikt att undersöka ljudets möjligheter som kom- munikationsmedium i utställningar. Syftet är att sprida ljus över detta förhål- landevis outforskade område som jag anser har många outnyttjade möjligheter. För att avgränsa min undersökning har jag valt att studera utställningen Dröm- mens syster som finns på Världskulturmuseet i Göteborg. Jag har intervjua någ- ra nyckelpersoner bakom utställningen för att förstå dess mål. Därefter har jag intervjuat ett antal besökare för att skapa en bild av hur dessa har upplevt besö- ket i utställningen. Drömmens Syster är en utställning om människor och myter kring Orinocoflo- den som visas. Utställningen vill berätta om de alltmer hotade folken kring flo- den som slingrar sig igenom Venezuela. Resultatet visar att ljud är ett bra medium för att förmedlar information och speciellt för att involvera besökaren i en upplevelse av regnskogen och livet kring vattenfallet. Vid flera tillfällen har museet lyckats förmedlar mer informa- tion än en bild skulle har gjort. Besökarna kan dra nytta av den lugnande effekt som vattenfallet har och uppleva skräck när ormen väser. På grund av det resul- tat jag fått hoppas jag att fler kommer att se möjligheterna i informationsför- medling via sinnen som till exempel auditiv kommunikation. / Sound is an interesting communication media that takes advantage of each persons individual ex- perience and conceptions and allows for many individual associations. Today museums can choo- se from a wide range of media (pictures, video, sound guides, computer and sound installations) to communicate with their audience because a greater variety of technical solutions is available. This paper has the goal to analys the possibilities of sound as a media of communication. The aim is to shed light on this relativly unexplored field that I think has a lot of potential. To narrow down my exploration, I have chosen to take a closer look at the exhibition Drömmens syster that is shown at the Världskulturmuseet in Gothenburg, Sweden. I have interviewed some key persons behind this exhibition to get an idea about the aim and I have interviewed a number of visitors to get a better understanding of how they experienced the exhibition. The exhibition Drömmens syster is about the more and more endangered people and their myths who live close by the Orinoco river in Venzuela. The conclusion from this essay shows that sound is a good media for communicating informa- tion. It is especially well suited to involve the audience in an experience of rain forest and the daily life around it. The museum suceeds several times to tell more by using sound than by just using pictures. Visitors can gain from the calming effect of the waterfall and they can get thrilled from the hiss of the snake. Therefor I sincerely hope that we are going to see more media con- cepts in the future that use auditive communication.
|
83 |
Utvärdering av automatiska snödjupsmätningar med en SR50A Sonic Ranging Sensor / Evaluation of automatic snow depth measurements with a SR50A Sonic Ranging SensorCarpman, Nicole January 2010 (has links)
I Sverige utförs dagligen observationer av snöns djup och utbredning under snösäsongen.Observationerna används till exempel för att årsvis avgöra maximalt snödjup, snötäckets första ochsista dag samt antal dygn med snötäcke på olika platser. Traditionellt utförs snödjupsmätningarmanuellt med en enkel mätpinne, men med ny teknik kommer nya möjligheter. Med enultraljudssnömätare kan automatiserade snödjupsmätningar utföras med bättre upplösning i bådetiden och rummet vilket därmed ger bättre uppfattning av snöns tillväxt, hopsjunkning samtsmältning och innebär att alla signifikanta förändringar i snötäcket garanterat kommer observeras. I denna utvärdering har en jämförelse gjorts av manuella och automatiska snödjupsmätningarutförda parallellt på samma plats men med olika frekvens. Instrumentet som utvärderats är enSR50A Sonic Ranging Sensor uppmonterad vid Institutionen för geovetenskapers mätstation vidUppsala universitet. Vid mätstationen görs även manuella snödjupsmätningar en gång per dag. Deautomatiska snödjupsmätningarna genomförs varje minut och medelvärdesbildas över ett 10minuters intervall. Utvärderingen visar att de båda metodernas mätresultat stämmer mycket väl överrens förutomen mer eller mindre systematisk skillnad. I medeltal ger Sonic Ranging Sensorn 1,6 cm större snödjup,något som till största del kommer av en osäkerhet vid kalibreringen av instrumentet. Resultaten visartydligt på en bättre upplösning hos de automatiska mätningarna men att de manuella mätningarnaändå fått med de stora förändringarna av snötäcket vad gäller tillväxt, minskning samt max‐ ochmindjup. Rådata från Sonic Ranging Sensorn visade på större och mindre fluktuationer som berodde påosäkra mätningar. Kvaliteten på mätningarna har avgjorts antingen med instrumentets inbyggdakvalitetsnummer eller utifrån max‐ och minvärden på snödjupet tagna under varje 10 minutersintervall. De faktorer som försämrade kvaliteten i mätningarna var först och främst snöfall, men ävenregndroppar eller snö som drev på grund av vinden gav försämrad kvalitet. Instrumentets känslighetför temperaturdifferensen i skiktet precis ovanför snöytan har också utvärderats vilket visade att detemperaturmätningar som görs i nuläget på 1,5 m höjd ger tillräckligt bra mätresultat. Det skildeendast 0,14 cm i medeltal om temperaturdifferensen togs med i beräkningarna av snödjupet. Förutom en systematisk skillnad visade sig drivbildning inom mätområdet vara den faktor som gavstörst skillnad mellan manuella och automatiska snödjupsmätningar. För att avgöra hurrepresentativa snödjupsmätningarna vid mätstationen är i jämförelse med närområdet och därmedockså eliminera påverkan av drivbildning genomfördes ytterligare manuella mätningar av snödjupetpå ett homogent fält i närheten. Resultaten visar att de manuella mätningarna vid mätstationen gerett för området representativt snödjup. / During the snow season, daily observations of snow depth and distribution are performed all aroundSweden. The observations are for example used to yearly determine maximum snow depth, first andlast day of snow coverage and number of days with snow coverage in different areas. Manual snowdepth measurements are traditionally performed with a simple measurement stick but with newtechnology new possibilities arise. With an ultrasonic snow depth sensor, automatic snow depthmeasurements can be performed with much better resolution in both time and space, thus give amore detailed picture of the growth, compaction and melting of the snow coverage. There is also norisk to miss out on any important changes in the snow coverage. In this evaluation, a comparison has been made between manual and automatic snow depthmeasurements performed parallel on the same place but with different frequency. The instrumentthat has been evaluated is a SR50A Sonic Ranging Sensor mounted at a measuring station near theDepartment of Earth Sciences, Uppsala University. At the measuring station manual snow depthmeasurements are made once a day. The automatic snow depth measurements are made everyminute and an average is taken over a 10 minute interval. The evaluation shows that the measuring results of both techniques follow each other very wellexcept for a more or less systematic difference. The Sonic Ranging Sensor gives in average 1.6 cmlarger snow depth which mostly is due to in uncertainty in the calibration of the instrument. Theresults clearly show a better resolution in the automatic snow depth measurements, although themanual measurements still show all significant changes of the snow coverage when it comes togrowth, compaction, maximum and minimum depth. Raw data from the Sonic Ranging Sensor showed some large amplitude and small amplitudefluctuations that were implemented by uncertainty in the measurements. The quality of themeasurements have been determined either with the built in quality number of the instrument orfrom maximum and minimum snow depth measurements during each 10 minute interval. The factorsthat reduced the quality of the measurements was mainly snow fall, but also rain drops or driftingsnow reduced the quality. The sensitivity of the instrument due to the temperature difference in thelayer just above the snow surface was also evaluated, showing that the temperature measurementsthat currently are performed at 1.5 m height give good enough measuring results. The difference wasonly 0.14 cm in average if the temperature difference was taken into account when calculating thesnow depth. Except for a systematic difference, drifting snow inside the measuring area was the factor givinglargest difference between manual and automatic snow depth measurements. To determine howrepresentative the snow coverage at the measuring station is compared to the local area, extramanual measurements were performed at a field near the station. The result shows that themeasuring station has a representative snow depth.
|
84 |
Vi kan inte blunda för öronen längre : En fallstudie om ljud som kommunikationsmedium i utställningen Drömmens systerCarleklev, Jan January 2008 (has links)
<p>Ljudet är ett intressant kommunikationsmedium som utnyttjar varje individs</p><p>egna erfarenheter och föreställningar där associationer får stort utrymme. Mu-</p><p>seer som idag kan välja från ett stort urval av medier har mycket att vinna ge-</p><p>nom att använda sig av ljud - inte enbart för att tekniken tillåter det.</p><p>Den här uppsatsen har för avsikt att undersöka ljudets möjligheter som kom-</p><p>munikationsmedium i utställningar. Syftet är att sprida ljus över detta förhål-</p><p>landevis outforskade område som jag anser har många outnyttjade möjligheter.</p><p>För att avgränsa min undersökning har jag valt att studera utställningen Dröm-</p><p>mens syster som finns på Världskulturmuseet i Göteborg. Jag har intervjua någ-</p><p>ra nyckelpersoner bakom utställningen för att förstå dess mål. Därefter har jag</p><p>intervjuat ett antal besökare för att skapa en bild av hur dessa har upplevt besö-</p><p>ket i utställningen.</p><p>Drömmens Syster är en utställning om människor och myter kring Orinocoflo-</p><p>den som visas. Utställningen vill berätta om de alltmer hotade folken kring flo-</p><p>den som slingrar sig igenom Venezuela.</p><p>Resultatet visar att ljud är ett bra medium för att förmedlar information och</p><p>speciellt för att involvera besökaren i en upplevelse av regnskogen och livet</p><p>kring vattenfallet. Vid flera tillfällen har museet lyckats förmedlar mer informa-</p><p>tion än en bild skulle har gjort. Besökarna kan dra nytta av den lugnande effekt</p><p>som vattenfallet har och uppleva skräck när ormen väser. På grund av det resul-</p><p>tat jag fått hoppas jag att fler kommer att se möjligheterna i informationsför-</p><p>medling via sinnen som till exempel auditiv kommunikation.</p> / <p>Sound is an interesting communication media that takes advantage of each persons individual ex-</p><p>perience and conceptions and allows for many individual associations. Today museums can choo-</p><p>se from a wide range of media (pictures, video, sound guides, computer and sound installations)</p><p>to communicate with their audience because a greater variety of technical solutions is available.</p><p>This paper has the goal to analys the possibilities of sound as a media of communication. The aim</p><p>is to shed light on this relativly unexplored field that I think has a lot of potential.</p><p>To narrow down my exploration, I have chosen to take a closer look at the exhibition Drömmens</p><p>syster that is shown at the Världskulturmuseet in Gothenburg, Sweden. I have interviewed some</p><p>key persons behind this exhibition to get an idea about the aim and I have interviewed a number</p><p>of visitors to get a better understanding of how they experienced the exhibition.</p><p>The exhibition Drömmens syster is about the more and more endangered people and their myths</p><p>who live close by the Orinoco river in Venzuela.</p><p>The conclusion from this essay shows that sound is a good media for communicating informa-</p><p>tion. It is especially well suited to involve the audience in an experience of rain forest and the</p><p>daily life around it. The museum suceeds several times to tell more by using sound than by just</p><p>using pictures. Visitors can gain from the calming effect of the waterfall and they can get thrilled</p><p>from the hiss of the snake. Therefor I sincerely hope that we are going to see more media con-</p><p>cepts in the future that use auditive communication.</p>
|
85 |
Caractérisation des voies pro-apoptotiques des récepteurs à dépendance à Shh et stratégies anti-tumorales / Characterization of Shh dependence receptors pro-apoptotic pathways and anti-tumor strategiesLe Guernevel, Solen 15 December 2015 (has links)
Les récepteurs à dépendance (RDs) ont la particularité d’induire deux types de signalisation selon la disponibilité de leur ligand. En présence de leur ligand, ils induisent une signalisation positive favorisant la survie, la prolifération ou encore la différentiation cellulaire, tandis qu’en son absence, ils induisent la mort cellulaire par apoptose. Ptc et CDON, tous deux récepteurs du morphogène Shh, appartiennent à la famille des RDs. Ces deux récepteurs sont impliqués dans le développement embryonnaire, mais aussi dans le contrôle de la tumorigenèse et de l’homéostasie. La plupart des mécanismes moléculaires de la signalisation proapoptotique de ces récepteurs sont encore inconnus. Nous avons donc étudié les voies de signalisations proapoptotiques de ces récepteurs grâce à un crible d’ARN interférents. Parmi les partenaires potentiels identifiés, nous nous sommes intéressés à l’IGFBP7, caractérisé comme gène suppresseur de tumeurs dans de nombreux cancers. Nous avons mis en évidence que la mort induite par Ptc implique un contrôle transcriptionnel d’IGFBP7 de façon p53 dépendante. Dans un second temps, nous nous sommes intéressés au rôle des voies apoptotiques des récepteurs Ptc et CDON dans des cancers colorectaux associés à des maladies inflammatoires chroniques de l’intestin, pour lesquels il a été montré que le ligand Shh est surexprimé. La surexpression du ligand est l’un des mécanismes d’échappement au contrôle apoptotique exercé par les RDs acquit par les cellules tumorales. Notre étude vise à démontrer que le ciblage de Shh dans ces cancers pourrait induire une réactivation des voies apoptotiques des RDs Ptc et CDON, et ainsi constituer une nouvelle stratégie anti-tumorale / Dependence receptors (DRs) are able to inducing two types of signaling according to their ligand availability. In the presence of their ligand, they induce a positive signaling promoting survival, proliferation or cell differentiation, whereas in its absence, they induce cell death by apoptosis. Ptc and CDON, both receptors of the morphogen Shh, belong to the DRs family. Both receptors are involved in embryonic development, but also in the control of tumorigenesis and homeostasis. Most of the molecular mechanisms of the pro-apoptotic signaling of these receptors remain unknown. We therefore studied both receptors pro-apoptotic pathways through a shRNA screen. Among the identified potential partners, we have been interested in IGFBP7 shown as a tumor suppressor gene in many cancers. Secondly, we studied the role of Ptc and CDON pro-apoptotic pathways in colorectal cancers associated with chronic inflammatory bowel diseases, in which it has been shown that Shh is overexpressed. Overexpression of the ligand is one mechanism of pro-apoptotic control escapement by DRs acquired by tumor cells. Our study aims to demonstrate that targeting Shh in these cancers could induce reactivation of DRs pro-apoptotic pathways and thus constitute a new anti-tumor strategy
|
86 |
Play me that Trait : An exploratory study on the association between Sonic logos and Brand personality traitsMellin, Anna, Olsson, Kewin, Svensson, Hannah January 2022 (has links)
The aim of this research is to explore the association between brand personality traits and sonic logos. The brand personality traits that are incorporated into this research are Responsibility, Activity, Aggressiveness, Simplicity and Emotionality. These traits constitute one of the two building blocks for this research. The other building block consists of the sonic logo, but more specifically, variations in mode and tempo. Because the research was exploratory in nature, a qualitative research strategy was deemed appropriate. Additionally, in order to explore the association between the two building blocks, one sonic logo was created in four versions where the mode and tempo shifted in different combinations. Semi-structured interviews were then conducted where the sonic logos were played. To find associations and patterns in the empirical material, coding inspired from grounded theory were used. To conclude, the first sonic logo version shows associations to the Activity and Emotionality dimensions. The second sonic logo version shows associations to the Responsibility, Aggressiveness and Activity dimensions. The third sonic logo version shows associations to the Activity, Simplicity and Emotionality dimensions. Lastly, the fourth sonic logo version shows associations to the Responsibility, Aggressiveness and Emotionality dimensions.
|
87 |
Single-hole sonic logging - A study of possibilities and limitations of detecting flaws in pilesPalm, Martin January 2012 (has links)
As a part of the Dutch development program Geo-impulse, which aims to half the occurrence of geotechnical failures in civil engineering projects inside the Netherlands by 2015, this master thesis is investigating how to trace imperfections in bored piles at an early stage. The objective is to carry out literature study on suitable methods and then focus the research on one particular method. The basis of the research is the single-hole sonic logging method. Field and laboratory measurements are carried out with the aim to investigate the detection range of the method as well as try to apply more advanced post-processing techniques. Results from the measurements are discussed and also a comparison between single-hole sonic logging and the better standardized test cross-hole sonic logging is made. The results indicate that single-hole sonic logging has a small detection range inside a bored pile, especially compared to cross-hole sonic logging. Also more advanced post-processing techniques fails or make the test to advance to use on a daily basis. Finally the recommendation is to carry on research with other techniques which in scientific papers have showed some promising results.
|
88 |
Hearing, Remembering, and Branding: Guidelines for Creating Sonic LogosKrishnan Palghat, Vijaykumar 11 August 2009 (has links)
No description available.
|
89 |
Experimental And Computational Investigations Of Underexpanded Jets From Elliptical Sonic NozzlesRajakuperan, E 03 1900 (has links)
Three dimensional nozzles and jet flows have attracted the attention of many researchers due to their potential application to many practical devices. Rectangular nozzles are considered for short/vertical take off and landing aircrafts for achieving powered lift. Axisymmetric nozzles with lobes, tabs or slots and elliptical nozzles are considered for noise reduction in aircrafts and mixing augmentation in airbreathing rockets. Interaction of supersonic jets with solid
surface, as in the case of retro and ullage rockets in launch vehicles and interaction of multiple jets as in the case of launch vehicles with multiple booster rockets/multiple nozzle engines are of practical importance. Design of rockets and aircrafts employing these nozzles needs the understanding of the structure and behaviour of the complex three dimensional supersonic jets issuing from these nozzles. The problem is so complex that different investigators have addressed only some specific aspects of the problem and there is much more to be done to fully understand these flows. For example, in the case of rectangular nozzle with semi circular ends (known as elliptical nozzle), the investigations have been limited to a single nozzle of aspect ratio 3,0 and pressure ratio (ratio of the total pressure to ambient pressure) 3.0. Further, the measurements were made in the far field subsonic region beyond a distance of 20 times the equivalent nozzle radius (RJ.
For the present study, the elliptical sonic nozzle of the type mentioned above was chosen, as it offered simplicity for manufacturing and carrying out computations, but has all the complex features associated with the three dimensional jets. A systematic study to understand the mean flow structure and the effect of important governing parameters like
ratio and pressure ratio on the flow development process of the jet issuing from Navier-Stokes equations.
The experimental study revealed many interesting flow features. It was found that the Underexpanded jet issuing from elliptical sonic nozzle spreads rapidly in the minor axis plane while it maintains almost constant width or contracts in the major axis plane. However, the gross spreading of this jet is much higher compared to the axisymmetric jet. The higher spreading rates experienced in the minor axis plane compared to the major axis plane of this 'et, results in the jet width in the minor axis plane to become higher than that in the major axis plane. The longitudinal location, where this occurs is called the axis switching location. This kind of axis switching phenomenon is known to exist for subsonic elliptical jets. However, for the present supersonic jets, the axis switching locations are much closer to the nozzle exit compared to the subsonic cases reported. It was further found that this location strongly depends on the pressure and aspect ratios. A critical pressure ratio was found to exist for each nozzle at which the axis switching location is the farthest. Above the critical pressure ratio, the axis switching location was observed to move upstream with the increase in the pressure ratio and is controlled by the
complex interactions of shock and expansion waves near the nozzle exit. Below the critical pressure ratio, the axis switching location moves upstream with the decrease in pressure ratio and is controlled by some kind of instability in the minor axis plane.
The shock structure present in the underexpanded jet from an elliptical nozzle was also observed to depend on both pressure and aspect ratios. For some aspect ratios and pressure ratios, the shock pattern observed in both the major and minor axis planes are similar to that of an axisymmetric jet, where the incident barrel shock and the Mach reflection (from the edges of the Mach disk) are present. But for all other cases, this shock
continues to be seen only in the major axis plane. Whereas, in the minor axis plane, the incident shock is absent in the shock pattern.
Detailed measurement in the jet cross sectional planes, for the case of aspect ratio 2.0 nozzle, shows that the cross sectional shape changes along the length and it becomes almost a circle at the axis switching location. Further downstream, the jet spreads rapidly in the minor axis plane whereas no significant change in the width of the jet in the major axis plane is observed. Far downstream, the jet boundary appears like a distorted ellipse with its major and minor dimensions lying respectively in the minor and major axis planes of the nozzle. The elongated shape of the jet cross sections at locations downstream of the axis switching point gives the impression that the entire flow in the major axis plane is turned towards the minor axis plane. This effect appears to be predominant at high pressure ratios.
The computed near field shock structure in the planes of symmetry, pitot pressure distributions, cross sectional shape of the jet and the spreading pattern agree very well with the experimental results. In addition to this, the present computational method gives the detailed near field flow structure including the azimuthal extent of the incident shock, cross flow details and distributions of flow variables. It is shown that the present inviscid methodology can also predict the axis switching point accurately if it occurs before the formation of the Mach disk and it demonstrates that the jet growth phenomenon in the near field, atleast, is mainly controlled by the inviscid flow process. The computed results have shown that changes in the jet cross sectional shape in the near field is caused mainly by the interaction of compression and expansion waves with each other and with the constant pressure boundary. The inviscid method seems to be able to capture the complicated secondary cross flow structure (indicating presence of longitudinal vortices) of the elliptical jet.
The complex mean flow structure in the near field region of the jet issuing from elliptical nozzles and the effect of nozzle aspect ratio and pressure ratio on the structure are brought out clearly in the present study. The mechanism governing the spreading and the axis switching characteristics are also brought out. Thus the present experimental and computational investigations give a comprehensive understanding of the mean flow structure of the underexpanded jets issuing from elliptical nozzles. Further studies are required to understand the other aspects of the elliptical jets as well as other three-dimensional jets. Some of these studies are identified for future work.
|
90 |
Rôle de la protéine Sonic Hedgehog dans la migration des cellules musculaires lisses et le recrutement des cellules murales sur les néovaisseaux : implication dans l’action de PDGF BB / Role of Sonic Hedgehog in smooth muscle cell migration and mural cell recruitment onto the neovessels : involvement in PDGF BB actionYao, Qinyu 09 October 2012 (has links)
Recruitment of mural cells, i.e. pericytes and smooth muscle cells (SMC), is essential to improve the maturation of newly formed vessels. One of the major factors involved in this process is the endothelial cell-secreted Platelet-Derived Growth Factor BB (PDGF BB). Sonic hedgehog (Shh) has also been suggested to promote the formation of larger and more muscularized vessels, but the underlying mechanisms involved have not yet been elucidated. We first identified Shh as a target of PDGF BB and found that SMC respond to Shh not only by upregulating the Gli1-dependent canonical pathway, but also by activating ERK1/2 and PI3K-dependent non-canonical pathways. Moreover, we found that PDGF BB-induced SMC migration, involves Shh-dependent PI3K, ERK1/2 and Gli1 activation. In the mouse model of corneal angiogenesis, PDGF BB and Shh were expressed by endothelial cells and mural cells of VEGF-induced newly formed blood vessels, respectively. PDGF BB inhibition reduced Shh expression, confirming that Shh is a target of PDGF BB, as demonstrated by in vitro experiments. Finally, we found that inhibition of either PDGF BB or Shh signaling reduced NG2+ mural cell recruitment into neovessels and subsequently reduced the neo-vessel lifespan. In this work, we demonstrate, for the first time, that Shh is a key mediator of PDGF BB-induced mural cell migration and recruitment into neo-vessels and elucidates the molecular signaling pathway involved in this process. / Recruitment of mural cells, i.e. pericytes and smooth muscle cells (SMC), is essential to improve the maturation of newly formed vessels. One of the major factors involved in this process is the endothelial cell-secreted Platelet-Derived Growth Factor BB (PDGF BB). Sonic hedgehog (Shh) has also been suggested to promote the formation of larger and more muscularized vessels, but the underlying mechanisms involved have not yet been elucidated. We first identified Shh as a target of PDGF BB and found that SMC respond to Shh not only by upregulating the Gli1-dependent canonical pathway, but also by activating ERK1/2 and PI3K-dependent non-canonical pathways. Moreover, we found that PDGF BB-induced SMC migration, involves Shh-dependent PI3K, ERK1/2 and Gli1 activation. In the mouse model of corneal angiogenesis, PDGF BB and Shh were expressed by endothelial cells and mural cells of VEGF-induced newly formed blood vessels, respectively. PDGF BB inhibition reduced Shh expression, confirming that Shh is a target of PDGF BB, as demonstrated by in vitro experiments. Finally, we found that inhibition of either PDGF BB or Shh signaling reduced NG2+ mural cell recruitment into neovessels and subsequently reduced the neo-vessel lifespan. In this work, we demonstrate, for the first time, that Shh is a key mediator of PDGF BB-induced mural cell migration and recruitment into neo-vessels and elucidates the molecular signaling pathway involved in this process.
|
Page generated in 0.0583 seconds