No description available.

Αγγειογένεση καλείται ο σχηματισμός νέων αγγείων από προϋπάρχοντα δίκτυα αιμοφόρων αγγείων σε προηγουμένως ανάγγειες δομές. Η αγγειογένεση συμμετέχει σε μια πλειάδα νοσημάτων (π.χ. καρκίνος, ρευματοειδής αρθρίτιδα) συμβάλλοντας καθοριστικά στην παθογένεια αυτών των καταστάσεων και στην ανάπτυξη επιπλοκών. Στον οφθαλμό, η παθολογική αγγειογένεση στις διάφορες στιβάδες του οργάνου αποτελεί την κύρια αιτία μη αναστρέψιμης απώλειας της όρασης στον Δυτικό κόσμο, καθιστώντας επιτακτική την ανάγκη ανάπτυξης νέων αντι-αγγειογενετικών παραγόντων, ικανών να κατανεμηθούν ενδοφθαλμίως και να αναστείλουν αποτελεσματικά τόσο την εν εξελίξει όσο και την εγκατεστημένη αγγειογένεση. Η Παρστατίνη αποτελεί το ελεύθερο πεπτίδιο 41 αμινοξέων που προκύπτει από την πρωτεολυτική διάσπαση του αμινοτελικού άκρου του ανθρώπινου υποδοχέα PAR1 κατά την ενεργοποίησή του από τη θρομβίνη. Προηγούμενες πειραματικές μελέτες έχουν καταδείξει ότι η Παρστατίνη καταστέλλει την αγγειογένεση στον οφθαλμό και ασκεί καρδιοπροστατευτική δράση σε βλάβες εξ ισχαιμίας/επαναιμάτωσης. Επίσης, έχει δειχθεί ότι τα πεπτιδικά υπομόρια της Παρστατίνης, Π1-26 και Π24-41, παρουσιάζουν εξειδικευμένη δράση και επιδρούν εκλεκτικά στην προστασία του μυοκαρδίου και στην αναστολή της οφθαλμικής νεοαγγειογένεσης, αντιστοίχως. Σύμφωνα με αυτά τα πειράματα, οι δράσεις των Π1-26 και Π24-41 είναι σημαντικά ισχυρότερες από αυτές του μητρικού μορίου, Παρστατίνη. Σκοπός της τρέχουσας μελέτης είναι η διερεύνηση της ιστικής κατανομής in vivo της Παρστατίνης και των αναλόγων-πεπτιδίων (Π1-26, Π24-41) αυτής στον οφθαλμό και στον νεφρό επίμυος. Η Παρστατίνη και τα ανάλογα-πεπτίδιά της (Π1-26, Π24-41) σημασμένα με FITC χορηγήθηκαν υπό τον βολβικό επιπεφυκότα ή ενδοφλεβίως, σε υγιείς αρσενικούς επίμυες. Ακολούθως τα πειραματόζωα θανατώθηκαν σε διαφορετικά χρονικά διαστήματα και οι ιστοί (οφθαλμοί, νεφροί, μυοκάρδιο) απομονώθηκαν χειρουργικά. Κατόπιν κατάλληλης επεξεργασίας, ελήφθησαν τομές ιστών νωπού παρασκευάσματος, πάχους 10 μm, οι οποίες παρατηρήθηκαν σε μικροσκόπιο φθορισμού. Κατά την παρατήρηση των οφθαλμικών τομών με FITC-Παρστατίνη και αυτών με FITC-Π1-26, ισχυρό σήμα φθορισμού ανιχνεύτηκε στις θέσεις χορήγησης και στους περιοφθαλμικούς ιστούς. Δεν παρατηρήθηκε σήμα φθορισμού στις εσώτερες στιβάδες του οφθαλμού. Ειδικότερα για την FITC-Παρστατίνη, η κατανομή του σήματος φθορισμού δεν μεταβλήθηκε σε διαφορετικά χρονικά διαστήματα που κυμάνθηκαν από 30 λεπτά έως 19 ώρες. Συγκριτικά με τα παραπάνω αποτελέσματα, οι αντίστοιχες οφθαλμικές τομές με FITC-Π24-41 ανέδειξαν ισχνό σήμα φθορισμού στις θέσεις χορήγησης και στους περιοφθαλμικούς ιστούς, χωρίς να συνοδεύεται από σήμα φθορισμού στις έσω ανατομικές δομές του οργάνου. Στις τομές νεφρού και μυοκαρδίου, ο ισχυρός αυτοφθορισμός δεν επέτρεψε τη μελέτη της ιστικής κατανομής των πεπτιδίων. Συμπερασματικά, καταδεικνύεται ότι η χορήγηση υπό το βολβικό επιπεφυκότα της Παρστατίνης και των πεπτιδικών αναλόγων της, του Π1-26 και του Π24-41 δεν αποτελεί την ενδεδειγμένη οδό χορήγησης για την ενδοφθάλμια κατανομή των χορηγούμενων ουσιών. / Angiogenesis refers to the formation of new blood vessels from pre-existing vasculature in previously avascular structures. Angiogenesis is an important component of numerous diseases (such as cancer, rheumatoid arthritis etc), contributing in the pathogenesis of these conditions. In the western world, pathological ocular angiogenesis constitutes the major cause of irreversible vision loss. Consequently, this fact gives rise to the need for the development of new anti-angiogenic agents, characterized by successful intraocular delivery and effective inhibition of developing angiogenesis and regression of already established vessels. Parstatin is a 41-amino acid peptide, released through proteolytic cleavage of the human PAR1 receptor N-terminal region upon activation by thrombin. Experimental studies have demonstrated that Parstatin suppresses ocular neovascularization and has a potential therapeutic role in the protection of myocardium by ischaemia and reperfusion injury. In addition, it has been shown that the Parstatin fragments, P1-26 and P24-41, have distinct effects in protecting myocardium and inhibiting ocular neovascularization, respectively. In fact, these effects are more potent than the native Parstatin. The aim of the present study was the in vivo evaluation of tissue-distribution of Parstatin and its peptide fragments (P1-26, P24-41) in rat eyes and kidneys. To address this question, Parstatin and its peptide analogues (P1-26, P24-41) were conjugated with FITC. Pathogen-free male rats received subconjunctival or intravenous injections of the FITC-labeled peptides. Following euthanasia of rats at different time points after the injections were performed, the tissues (eyes, kidneys, hearts) were surgically excised from the respective animals. After treatment, the fresh-frozen tissues were sectioned sagittally into 10 μm thick slices and observed using fluorescence microscope. When sections of eyes treated with FITC-Parstatin and those ones treated with FITC-P1-26 were examined, intensive FITC signal was detected at the sites of administration and at periocular tissues. FITC signal was not observed in internal ocular layers. Regarding FITC-Parstatin, the distribution of specific signal showed no variability during different time intervals which ranged from 30 minutes to 19 hours. As compared to the above results, the respective ocular sections with FITC-P24-41 revealed weak FITC signal at the injection sites and at periocular tissues, accompanied by no detection of intraocular localization. On the other hand, high autofluorescence present in kidney sections and heart sections did not allow the investigation of tissue-distribution of the peptide molecules. In the present study, it appeared that subconjunctival administration of Parstatin and of its peptide fragments, P1-26 and P24-41, is not the appropriate route for the drug delivery into the internal ocular tissues.

No description available.

A variable that is capable of indicating one's cognitive and motor capacities has been the dream of many researchers. Until recently however, no researcher has seriously considered an independent variable that is obvious among all people regardless of race or culture. This variable is eye color. This paper is a review of the experimental literature in this field and covers many areas including sociability, perception, learning, athletic abilities, and a few medical anomalies. Several alternative hypotheses are also offered as reasons for the obtained correlations. These ideas include culture, learning, and environment. Two other hypotheses are also presented to explain why eye color does play an important role in determining one's response to environmental stimuli. These ideas include a genetic and physiological basis. It is the hope of this author that this review may stimulate other researchers to perform more experiments in the area to help determine the amount of influence that they eye color has in individual responses to the environment.

No / We consider and compare the various different kinds of flow that may take place in the anterior chamber of a human eye. The physical mechanisms re- sponsible for causing such flows may be classified as follows: (i) buoyancy-driven flow arising from the temperature difference between the anterior surface of the cornea and the iris, (ii) flow generated by the aqueous production of the ciliary body, (iii) flow generated by the interaction between buoyancy and gravity while sleeping while sleeping in a face-up position, (iv) flow generated by phakodenesis (lens tremor), (v) flow generated by Rapid Eye Movement (REM) during sleep. Each flow is studied using a traditional fluid mechanics/asymptotic analysis ap- proach. We also assess the veracity of a hypothesis that was recently advanced [see Maurice, D.M., 1998. The Von Sallman Lecture 1996: An ophthalmological explanation of REM sleep. Exp. Eye. Res. 66, 139¿145, for details] to suggest that, contrary to previous opinion, the purpose of REM during sleep is to ensure corneal respiration in the absence of the buoyant mixing that routinely takes place due to (i) above during waking conditions.

No / Aspheric intraocular lenses (IOLs) are designed to correct spherical aberration in pseudophakic eyes. We predict the benefit from correcting spherical aberration based on simulations and aberrometry of pseudophakic eyes implanted with spherical IOLs. METHODS Ray tracing was performed through a model eye with an equi-biconvex spherical IOL and with a spherical aberration-correcting aspheric IOL. The IOLs were increasingly tilted and/or displaced, and the resulting transverse aberrations of 169 rays were transformed into Zernike coefficients for different pupil sizes. The benefit from correcting spherical aberration at individual mesopic pupils was investigated by canceling in the sets of Zernike coefficients for 41 eyes implanted with a spherical IOL. RESULTS Both the model eye and the real eye data predict that age-related miosis reduces spherical aberration in the eye implanted with a spherical IOL to approximately 1/3 of the spherical aberration at a 6-mm pupil. A reduction of similar magnitude occurs when spherical aberration-induced non-paraxial defocus is corrected by a spectacle lens. For natural mesopic pupils, canceling the Zernike coefficient improved the objective image quality at a rate similar to changing defocus by 0.05 diopters. Average centration and tilt levels diminish the lead of aspheric IOLs over spherical IOLs, depending on the direction of decentration. CONCLUSIONS The benefit from correcting spherical aberration in a pseudophakic eye is limited for some or all of the following reasons: wearing glasses, age-related miosis, tilt and decentration of IOL, small contribution of spherical aberration to all aberrations, and intersubject variability

No / To present a computational model mapping visual field (VF) locations to optic nerve head (ONH) sectors accounting for individual ocular anatomy, and to describe the effects of anatomical variability on maps produced. A previous model that related retinal locations to ONH sectors was adapted to model eyes with varying axial length, ONH position and ONH dimensions. Maps (n = 11,550) relating VF locations (24-2 pattern, n = 52 non–blind-spot locations) to 1° ONH sectors were generated for a range of clinically plausible anatomical parameters. Infrequently mapped ONH sectors (5%) were discarded for all locations. The influence of anatomical variables on the maps was explored by multiple linear regression. Across all anatomical variants, for individual VF locations (24-2), total number of mapped 1° ONH sectors ranged from 12 to 90. Forty-one locations varied more than 30°. In five nasal-step locations, mapped ONH sectors were bimodally distributed, mapping to vertically opposite ONH sectors depending on vertical ONH position. Mapped ONH sectors were significantly influenced (P < 0.0002) by axial length, ONH position, and ONH dimensions for 39, 52, and 30 VF locations, respectively. On average across all VF locations, vertical ONH position explained the most variance in mapped ONH sector, followed by horizontal ONH position, axial length, and ONH dimensions. Relations between ONH sectors and many VF locations are strongly anatomy-dependent. Our model may be used to produce customized maps from VF locations to the ONH in individual eyes where some simple biometric parameters are known. / ustralian Research Council Linkage Project LP100100250 (with Heidelberg Engineering GmbH, Germany); Australian Research Council Future Fellowship FT0990930 (AMM); Australian Research Council Future Fellowship FT0991326 (AT)

This work provides an innovative solution for monitoring fatigue for users behind workstations. A web camera was adjusted to work in near infrared range and a system of 880 nm IR diodes was implemented to create an IR vision system to localize and track the eye pupils. The software developed monitors and tracks eyes for signs of fatigue by measuring PERCLOS. The software developed runs on the workstation and is designed to draw limited computational power, so as to not interfere with the user task. To overcome low-frame rate imposed by the hardware limitations and to improve real time monitoring, two-phases detection and tacking algorithm is implemented. The proposed system successfully monitors fatigue at a rate of 8 fps. The system is well suited to monitor users in command centers, flight control centers, airport traffic dispatches, military operation and command centers, etc., but the work can be extended to wearable devices and other environments.

Testing of eye tracking devices is done by humans looking at well defined stimuli. This way of testing eye trackers is not accurate enough because of human errors. The goal of this thesis is to design and construct reliable robotic eyes that can mimic the behaviour of human eyes. After a pre-study where human eyes, eye tracking and previous robotic eyes were studied, system requirements and specifications were formulated. Based on the re-quirements important design decisions were taken such as the use of RC servo motors, push rods, microcontrollers and a Raspberry Pi. Later the inverse kinematics of the movements and a saccade’s path planing were modelled. Additional mechanical de-sign features are rotation of the head and adjustment of the interpupillary distance. The robot is controlled using two types of application programming interfaces (APIs.) The first API is used to control the motors and the second API builds on top of the first API but is used to design paths of different eye movements between fixation points. All eye movement calculations are computed on the Raspberry Pi before the movements are communicated in real time to the microcontroller which directly performs the control signal. The robot was tested using the integrated lasers in the eyes and a video cam-era with slow motion capabilities to capture the projected laser dot on a wall. The properties tested are saccade, smooth pursuit, head rotation and eye tracking device compatibility. The results show high precision but not enough accuracy. The robot needs a few mechanical improvements such as removing the backlash in the rotat-ing joints on the eyes, decreasing the flexibility of some of the 3D printed parts and assuring symmetry in the design. The robot is a powerful testing platform capa-ble of performing all eye movement types with high-resolution control of both eyes independently through an API. / Eyetracking utrustning testas av människor som tittar på väldefinierade stimuli. Att testa eyetracking på det här sättet är inte tillräckligt noggrant på grund av mänskligt fel. Malet med detta examensarbete är att designa och bygga en pålitlig ögonrobot som kan härma beteendet hos mänskliga ögon. Efter en förstudie om mänskliga ögon, eyetracking och existerade robotögon formulerades system-krav och -specikationer. Baserat på dessa krav togs en del betydande designbeslut som att använda RC servomotorer, tryckstånger, mikrokontrollers och en Raspberry Pi. Senare modellerades den inverterade kinematiken av rörelserna och saccaders banor. Ytterligare mekaniska funktioner är rotation av huvudet och justering av avståndet mellan pupillerna. Roboten styrs med hjälp av två applikationsprogrammeringsgränssnitt (API). Det första API:et används för att styra motorerna och det andra API:et bygger på det första men används för att bygga rörelsevanor av olika ögonrörelser mellan fixationspunkter. Alla ögonrörelseberåkningar görs på Raspberry Pin innan rörelsen kommuniceras i realtid till mikrokontrollen som på direkten exekverar styrsignalen. Roboten testades med integrerade lasrar i ögonen och en kamera med slow motion funktionalitet för att fånga laser prickens projektion på en vägg. Funktioner som testades är saccader, smooth pursuit, huvudrotation och eyetracking kompatibilitet. Resultat visade en hög precision men inte tillräckligt hög noggrannhet. Roboten behöver några få mekaniska förbättringar som att få bort glappet i de roterande lederna på ögat, minska flexibiliteten i några av de 3D-utskrivna delarna och garantera symmetri i designen. Roboten är en kraftfull testplatform kapabel till att utföra alla typer av ögonrörelser med högupplöst kontroll av båda ögonen var för sig genom ett API.

This thesis establishes parallel claims about how women’s autobiography as a genreintersects with fiction as a means to share an author’s opinions on issues of race, gender,class, and topics that the publishing industry deems ‘controversial’, using Zora Neale Hurston’s works Their Eyes Were Watching God and Dust Tracks on a Road as points of comparison. Throughout this thesis, I will show that Their Eyes Were Watching God is a novel that by virtue of its content is a political novel because of how it represents an overlooked demographic of people and the novel’s ripple effect on later black female writers as one of the first novels that celebrates black female joy. TEWWG does the work of literary representation that publishers did not allow DToaR to do because of the fear that the book would not sell as well if it included more of Hurston’s own political perspective. The second claim that I make is that TEWWG is first dismissed because of its lack of ‘seriousness’ in subject matter by Hurston’s peers, but its use of nature metaphors like the horizon and the tree and motifs like desire and dreams allow for issues of gender, race, class, and love to be discussed because they are shrouded in a literary image disguise.