Functional characterization of retina and optic nerve after acute and chronic elevation of the intraocular pressure in rats

Purpose. To characterize the pupil light reflex (PLR), electroretinographic (ERG) and tonometric parameters in healthy, acute and chronic hypertensioe rat eyes. Methods. Brown Norway rats were used for experiments. The PLR was evaluated with a computerized pupillometer, ERGs were recorded simultaneously from both eyes and intraocular pressure (IOP) was measured with a Tonopen. Retinal ischemia was induced in rats by acutely increasing the IOP (110 mmHg/60 minutes), while chronic ocular hypertension was induced by cauterizing vortex and episcleral veins. Results. The analysis of the PLR parameters confirmed the consensual PLR was significantly smaller in amplitude (p = 0.03) and increased latency time (p = 0.001) compared to the direct PLR in healthy rats. Acute ocular ischemia caused significant decrease in retinal function. Preoperative values for the PLRratio in rats exposed to the acute ocular ischemia (ratio = consensual/direct PLR) were 76.7 +/- 2.6 (mean +/- SEM; %). 24h postoperatively the PLR ratio was 15.2 +/- 12.8, 10 days postoperatively 11.6 +/- 9.8, 20 days postoperatively 26.5 +/- 8.0 and 28 days postoperatively PLRratio was 33.27 +/- 9.3. However, at day 35 the PLR was significantly recovered when compared to the 24h postoperative values (PLR ratio = 41.1 +/- 7.3%, p \u3c 0.01, Repeated measures ANOVA). 42 days after surgery the PLR started to decrease once again in the operated eyes. Electroretinographic amplitudes followed a similar pattern. Seven days after surgery 5/14 rats, which received cauterization of the vortex and episcleral veins developed significant elevation of the IOP in operated eyes (p = 0.0004; Paired t-test). Elevation of the IOP was sustained at 3 (p = 0.002) and 5 (p = 0.007) weeks postoperatively. However, IOP values did not significantly differ between control and operated eyes 8 weeks postoperatively (p = 0.192, Paired t-test). Rats with elevated IOP had significant pupil defects at 7 (p \u3c 0.05, Repeated measures ANOVA, n = 5) and 28 days postoperatively (p \u3c 0.05), but not at 62 days postoperatively (p \u3e 0.05) comparing to preoperative values. Rats with elevated IOP displayed a significant decrease in ERG amplitudes in operated eyes at 4 but not at 8 weeks postoperatively. Conclusions. Functional monitoring of the ERG and PLR is sensitive technique for the detection of retina and optic nerve deficits after acute and chronic elevation of the IOP

Correlation of liquid-liquid equilibria of non-ideal binary systems using the non-random, two-liquid model

The non-random, two-liquid (NRTL) model with three different forms of temperature dependant parameters was used to correlate the liquid- -liquid equilibrium data for systems of alcohols with alkanes, and alcohols with two ionic liquids: 1-butyl-2,3-dimethylimidazolium tetrafluoroborate ([bmmim][BF4]) and 1-butyl-3-ethylimidazolium tetrafluoroborate ([beim][BF4]). Different temperature dependences of the NRTL parameters were tested on thirteen literature experimental liquid-liquid equilibrium data for binary systems

Implementacije senzora za metrologiju i prenos podataka u industriji traktora

Contemporary solutions in industry of tractor necessitated the need for introducing an increasing number of physical - technical sensors, as the testing and development, and as the serial production of tractors. The very principle of the sensor and measuring, not much changed. The greatest improvement in real monitoring and data processing, which enables the development, modern computer technology and DSP processors, powerful performance and small size. Data can be collected and processed for testing, development and exploitation of the tractor, or with some of the wireless protocol to transfer the headquarters where you can track the performance of tractors. This can be more effectively achieved by improving the efficiency, reliability and ergonomics of tractors.Savremena rešenja u traktorskoj industriji nametnula su potrebu za uvođenjem sve većeg broja fizičko – tehničkih senzora, kako pri ispitivanju i razvoju, tako i pri serijskoj proizvodnji traktora. Sam princip senzora i merenja, se nije puno promenio. Najveći napredak je u realnom monitoringu i obradi podataka, što je omogućeno sa razvojem, savremenih računarskih tehnologija i DSP procesora, moćnih performansi i malih dimenzija. Podaci mogu da se prikupljaju i obrađuju radi ispitivanja, razvoja i eksploatacije u samom traktoru, ili da se sa nekim od bežičnih protokola prenesu do centrale gde se mogu pratiti performanse traktora. Ovim se može na efikasniji način postići poboljšanje efikasnosti, pouzdanosti kao i ergonomije traktora

Enhancing active learning and critical thinking in higher education: university teachers' perceptions of the ALCT program

This paper describes the transformation of the Reading and Writing for Critical Thinking (RWCT) program into the Active Learning and Critical Thinking in Higher Education program (ALCT) as implemented in the higher education context in Croatia, based on the RWCT Prague conference in 2001. The initial experiences with program implementation are described, with a particular emphasis on innovations intended to increase the relevance of the program for university teachers. Preliminary evaluation results are presented

Characterization of structure and function of the mouse retina using pattern electroretinography, pupil light reflex, and optical coherence tomography

Objective  To perform in vivo analysis of retinal functional and structural parameters in healthy mouse eyes. Animal Studied  Adult C57BL/6 male mice (n = 37). Procedures  Retinal function was evaluated using pattern electroretinography (pERG) and the chromatic pupil light reflex (cPLR). Structural properties of the retina and nerve fiber layer (NFL) were evaluated using spectral-domain optical coherence tomography (SD-OCT). Results  The average pERG amplitudes were found to be 11.2 ± 0.7 μV (P50-N95, mean ± SEM), with an implicit time for P50-N95 interval of 90.4 ± 5.4 ms. Total retinal thickness was 229.5 ± 1.7 μm (mean ± SEM) in the area centralis region. The thickness of the retinal nerve fiber layer (mean ± SEM) using a circular peripapillary retinal scan centered on the optic nerve was 46.7 ± 0.9 μm (temporal), 46.1 ± 0.9 μm (superior), 45.8 ± 0.9 μm (nasal), and 48.4 ± 1 μm (inferior). The baseline pupil diameter was 2.1 ± 0.05 mm in darkness, and 1.1 ± 0.05 and 0.56 ± 0.03 mm after stimulation with red (630 nm, luminance 200 kcd/m2) or blue (480 nm, luminance 200 kcd/m2) light illumination, respectively. Conclusions  Pattern electroretinography, cPLR and SD-OCT analysis are reproducible techniques, which can provide important information about retinal and optic nerve function and structure in mice

Recovery of canine retina and optic nerve function after acute elevation of intraocular pressure: implications for canine glaucoma treatment

Purpose  To characterize the timing and extent of functional recovery in healthy canine eyes exposed to acute elevation of intraocular pressure (IOP). Methods  Acute elevation of IOP was induced in 14 healthy Beagles by elevating IOP above the levels of systolic blood pressure for 60 min (average elevation was between 100 and 160 mmHg). Menace, dazzle and pupillary light reflexes (PLR) were tested at 1, 7, 14 and 28 days post elevation. Optical coherence tomography was used to evaluate retinal thickness preoperatively and at 15 and 30 days post elevation. Results  One day post elevation all animals were blind in the operated eye (no positive menace), 5/14 had positive PLR and 10/14 had positive dazzle response. Seven days post elevation 4/14 animals had positive menace response and all animals (14/14) had positive dazzle and PLR responses. Fourteen and 28 days post elevation all animals had positive menace, PLR and dazzle responses. Optical coherence tomography analysis revealed significant thinning of the inferior retina (pre elevation: 156.3 ± 4.8 µm; 15 days post elevation: 125 ± 10.4 µm; 30 days post elevation 123 ± 11.9 µm; P \u3c 0.01, anova). The superior retina, however, did not show any detectable decrease in thickness compared to control eyes (pre elevation: 193.8 ± 2.6 µm; 15 days post elevation: 176.9 ± 8.5 µm; 30 days post elevation 176.9 ± 7 µm; P = 0.057, anova). Conclusions  Detailed functional and morphologic analysis revealed precise information about retinal damage after acute elevation of IOP. Canine retina has the capacity to recover at least some visual function even at 14 days after acute elevation of the IOP. More aggressive medical and surgical treatment of canine glaucomatous patients may be indicated despite complete loss of visual function, PLR and dazzle responses in early days after development of an acute glaucomatous attack

Functional Characterization of Retina and Optic Nerve after Acute Ocular Ischemia in Rats

purpose. To functionally characterize the status of the rat retina and optic nerve after acute elevation of intraocular pressure (IOP) and to determine the dynamics of the pathologic changes in the ischemic retina and optic nerve. methods. Retinal ischemia was induced in rats by acutely increasing the IOP (110 mm Hg/60 minutes). Direct and indirect pupil light reflexes (PLRs) were recorded from the noninjured eye, and electroretinograms (flash and flicker ERG) were recorded from the injured and control eyes before and after surgery. Amplitudes and latencies were calculated for each recording session. results. Preoperative PLRratios (indirect/direct PLR) were 76.7 ± 2.6 (mean ± SEM). Twenty-four hours after surgery the PLRratio was 15.2 ± 12.8, 10 days after surgery, 11.6 ± 9.8; 20 days after surgery, 26.5 ± 8.0; and 28 days after surgery, 33.27 ± 9.3. However, at day 35, the PLR had significantly recovered (41.1 ± 7.3) when compared with the 24-hour postoperative ratios (P \u3c 0.01, repeated-measures ANOVA). Forty-two days after surgery, the PLRratio started to decrease once again in the injured eyes (28.7 ± 5.9). Electroretinographic amplitudes (full-field flash ERG) followed a similar pattern. Cone responses (flicker ERG) were measured 42 days after surgery and revealed defects in injured eyes (control eyes: 46.6 ± 2.9 μV, injured eyes: 3.4 ± 1.7 μV). Histologic analysis revealed ischemic damage to all retinal layers, with the primary defects localized to the central retina. conclusions. Acute ocular ischemia causes a significant decrease in retinal function, as measured by PLR and ERG, although over time the rat retina and optic nerve show partial regain of function

Aplikacija neophodne traktorske elektroopreme sa ciljem izbora dobavljača

It was noticed that a certain number of suppliers of electronic equipment put on the market the goods of unknown origin in latest years. Therefore, tractor manufacturers before proceeding with installation of product they must carry out necessary tests in terms of quality checks to protect the validity of their products out to market. Basic remarks were that the suppliers of electrical equipment didn’t have complete technical documentation for product they offer, in order to fulfill quality of the tractor as whole product. Electrical equipment should have a satisfactory quality which is evidenced by the necessary technical documentation and the certification with the applicable standards for their purposes. When the tractor manufacturer seeks from the suppliers of electrical equipment for cooperation, it requires that with received sample and is all relevant technical documentation. As for the manufacturer it is necessary for the methodology and procedures are how to test the observed sample. This means that by determining the basic technical and functional characteristics, manufacturer has to define technical conditions and requirements for technical criteria by assessing required quality. Thus, the results are compared with the established technical requirements and the criteria in technical documentation are based on which appreciation is made and in the validity of the quality-of-technical system. Following these tests and comparative analysis of the manufacturer decides to have positive evaluated a sample of electronic equipment that can be mounted on the respective tractors. So far, the tractor manufacturer IMR performs testing of certain types for electronic equipment and tractor according to the prescribed procedures and methodology, and by that accordingly choose suppliers.Uočeno je da određeni broj dobavljača elektroopreme u zadnjim godinama plasira na tržište robu nepoznatog porekla. Proizvođači traktora pre ugradnje moraju da izvrše potrebna ispitivanja, u smislu provere kvaliteta, kako bi zaštitili valjanost svoga proizvoda. Osnovne primedbe su da snabdevači elektroopreme ne poseduju kompletnu tehničku dokumentaciju za proizvod koji nude, čime dovode u pitanje kvalitet traktora u celini. Elektrooprema treba da ima zadovoljavajući kvalitet, što se dokazuje potrebnom tehničkom dokumentacijom i sertifikacijom po važećim standardima za svoje namene. Kada proizvođač traktora potražuje elektroopremu od dobavljača, on zahteva da uz pristigle uzorke bude i relevantna tehnička dokumentacija. Kod proizvođača, metodologije i procedure podrazumevaju način ispitivanja posmatranog uzorka. Ispitivanja se odnose na određivanje osnovnih tehničko-funkcionalnih karakteristika, tehničke uslove i zahteve kao i tehničke kriterijume za ocenu potrebnog kvaliteta. Na taj način dobijeni rezultati upoređuju se sa postavljenim tehničkim zahtevima i kriterijumima u tehničkoj dokumentaciji, na osnovu čega se donosi oceana o valjanosti upotrebnog kvaliteta tehničkog sistema. Nakon obavljenih ispitivanja i uporednih analiza, proizvođač donosi odluku da se pozitivno ocenjeni uzorak elektroopreme može ugraditi na odnosne traktore. Dakle i proizvođač traktora IMR vrši ispitivanja određene vrste traktorske elektroopreme po propisanim procedurama i metodologiji i shodno tome vrši odabir dobavljača

Karakteristike powershift menjača kod poljorivrednih traktora

This paperwork paper presents and analises the functioning of one main tractor assemblies, precisely the transmission. This includes and it is applied to a technologically advanced gearbox solution such as Full PowerShift. This type of gearbox is the most represented currently on the market because it is transmission without interruption of power flow. Also, there will be adequate proportional solenoid valve that is an integral part of the transmission. With its construction and function, it provides specificity in gear changes. Changing gears without interrupting the power stream, during transportation does not result in stopping the tractor and changing the engine mode due to load and nominal power of machine. The overrun and in between struggle of manufacturers for the most efficient and rational solution today has led to the offer of an extremely wide range of various gearboxes. Gearboxes with different electronical elements give different exploatations characteristics. In this way, they form differential types of gearboxes, which different so much that it is almost impossible to capture them in a proper analysis.Ovaj rad daje prikaz i analizu funkcionisanja jednog od traktorskih sklopova, tačnije transmisije. To se odnosi na tehnološki napredno rešenje menjačkih sklopova kao što je Full PowerShift. Ovaj tip menjača je najzastuplјeniji trenutno na tržištu jer je menjač bez prekida toka snage. Takođe, biće reči i o proporcionalnom solenoidnom ventilu koji je sastavni deo ove transmisije. Svojom konstrukcijom i funkcijom omogućava specifičnost u promeni stepena prenosa. Promena stepeni prenosa bez prekida toka snage, u transportu nema za posledicu zaustavlјanje traktora i promene režima rada motora. Konkurencija proizvođača za najefikasnijim i najracionalnijim rešenjem uslovila je danas ponudu izuzetno širokog spektra razičitih menjačkih sklopova. Menjački sklopovi sa upotrebom različitih elektronskih elementa daju različite eksploatacione karakteristike. Na taj način formiraju pojedine tipove menjača, koji se u tolikoj meri razlikuju da ih je skoro nemoguće obuhvatiti jednom analizom

Identifikacija uglova zakretanja upravljačkih točkova kod poljoprivrednih traktora

This paper presents methodology applied for testing and calculation of steering wheels rotation angles in IMR tractors. Importance of this methodology is in defining minimal rotation angles of steering wheels under which agricultural tractor hold basic working functions when new assembly is mounted or, in our case, with installed new drive axle. By installing new drive axle on tractors R-76 DV and R-65 DV it has been noticed that tractor construction is slightly changed within assembly of newly developed chassis. From this reason certain test was needed to define relining procedures, due to introducing newly product in production process. This paper presents some results of the testing applied.Rad prezentuje metodologiju pomoću koje je izvršeno ispitivanje i proračunavanje uglova zakretanja upravljačkih točkova kod IMR–ovih traktora. Značaj ove metodologije je u definisanju minimalnih uglova zakretanja upravljačkih točkova pri kojima poljoprivredni traktor zadržava osnovne radne funkcije pri ugradnji novog sklopa u odnosnom slučaju novog pogonskog mosta. Ugradnjom novog pogonskog mosta na traktore R-76 DV i R-65 DV, delimično se izmenila konstrukcija traktora te je u sklopu tog novo definisanog konstruktivnog stanja, bilo potrebno obaviti određena ispitivanja definisana odgovarajućim procedurama koje se primenjuju pri uvođenju novog proizvoda u proizvodni proces. Ovaj rad upravo prezentuje neke rezultate ovakve vrste ispitivanja