COMPARATIVE ANALYSIS OF THE PULSE WIDTH MODULATION METHODS FOR THE PROPULSION FREQUENCY CONVERTER

U radu su pomoću simulacijskog modela razvijenog u programskom alatu Simulink analizirane tri najčešće korištene metode širinsko-impulsne modulacije: metoda histereze, sinusno-trokutna metoda i metoda modulacije prostornog vektora. Simulacija je izvršena u vremenskoj domeni, a za analizu rezultata je primijenjen kvazistacionarni pristup. Usporedno su analizirani valni oblici i harmonička izobličenja statorskih napona i struja propulzijskog elektromotora pri različitim brzinama vrtnje i odgovarajućim opterećenjima za sve tri metode modulacije. Dobiveni rezultati pokazuju da su pri približno istim frekvencijama prekapčanja ukupna harmonička izobličenja napona i struje propulzijskog elektromotora uvjerljivo najmanja kod metode modulacije prostornog vektora, a najveća kod metode histereze. Indeks frekventne modulacije ima relativno mali utjecaj na THDu, ali vrlo velik utjecaj na THDi.In this paper, using a simulation model developed in Simulink, the three most common Pulse Width Modulation techniques are analyzed: hysteresis current control method, sine-triangle method, and space vector modulation method. Simulation is performed in the time domain and a quasi-stationary approach is applied for the simulation results analysis. Waveforms and harmonic distortion of propulsion motor’s stator voltage and current are analyzed at different speeds and appropriate loads for all three modulation methods. The obtained results indicate that, at approximately equal switching frequencies, the total harmonic distortions of propulsion motor voltage and current are arguably lowest when the space vector modulation method is used and are highest with the hysteresis current control method. Frequency modulation index has a relative small impact on THDu and a very large impact on THDi

Identifikacija, lokalizacija i kvantifikacija subpopulacija crijevnih imunosnih stanica prasadi tijekom prvih sedam tjedana postnatalnog razvitka.

By using immunohistology and digital image analysis for histomorphometry, we investigated the influence of porcine postnatal development on distribution and quantitative patterns of naïve/memory lymphoid cell subsets (CD45RA+, CD45RC+, respectively), helper/cytotoxic T cell subsets (CD4+, CD8+, respectively) as well as of IgA+ plasma cells in the gut-associated lymphoid tissues (GALT) of pigs reared under intensive conditions during the first 7 weeks of life. Current research on the postnatal ontogenesis/maturation of porcine small intestinal mucosal immune system have shown that newborn pigs are immunologically rather immature and, thus, totally dependent on passively acquired immunity. Their jejunal mucosa almost lacks immune cells, with the exception of a low number of CD45RA+ lymphoid cells (1.25×10-5) at Day 0 post partum. A very few CD45RC+ lymphoid cells (8.79×10-6 ) appeared at Day 7, followed by a similar number of IgA+ plasma cells (7.65×10-6) which were observed at Day 14. Such first signs of the postnatal development of both innate and adaptive immunity by identification/localization of tested cell subsets residing porcine GALT, i e. jejunal mucosal sites are proceeded by a lag period of three weeks until the appearance of low quantities of CD4+ (3.62×10-5) and CD8+ (3.13×10-5) T cells at Day 35 after birth. After that phase of early postnatal development of the crucial cell subsets participating in the antigen-specific immunity on the gut mucosal surfaces of young pigs, further progress was visible through their different distribution patterns within the jejunal mucosa compartments, and a gradual increase in their numbers, particularly between Day 35 and Day 49 of age. A significant increase was recorded within that period in the numbers of naïve, memory and plasma cells, whereas the number of helper and cytotoxic T cells only slightly increased between Day 42 and Day 49 of life.Pomoću imunohistoloških i histomorfometrijskih analiza računalnom obradom slike istraživali smo utjecaj postnatalnog razvitka u svinje na distribucijske i kvantitativne pokazatelje subpopulacija djevičanskih/ memorijskih limfoidnih stanica (CD45RA+ odnosno CD45RC+), pomoćničkih/citotoksičnih T-stanica (CD4+ odnosno CD8+), kao i za IgA+ plazma stanice u limfatičkim tkivima probavnog sustava (LTPS) prasadi uzgajane u intenzivnim uvjetima tijekom prvih 7 tjedana života. Istraživanje postnatalnog razvitka/sazrijevanja imunosnog sustava sluznice tankoga crijeva svinje pokazalo je da je neonatalna prasad imunološki prilično nezrela, pa je stoga u potpunosti ovisna o pasivno stečenoj imunosti. U sluznici njihovog jejunuma gotovo potpuno nedostaju imunosne stanice, s izuzetkom malobrojnih CD45 RA+ limfoidnih stanica (1,2510–5) 0. dana nakon prasenja. Sedmog dana post partum pojavljuje se nešto malo CD45RC+ limfoidnih stanica (8,7910-6), a potom se 14. dana mogu identificirati malobrojne IgA+ plazma stanice (7,650-6). Ovi prvi znakovi postnatalnog razvitka urođene i stečene imunosti, temeljem identifi kacije/lokalizacije subpopulacija istraživanih stanica koje naseljavaju LTPS svinje, odnosno sluznicu jejunuma, nastavljaju se nakon razdoblja od tri tjedna do pojavljivanja malobrojnih CD4+ (3,6210-5) i CD8+ (3,13 10-5) T-stanica 35. dana nakon prasenja. Nakon ove faze ranog postnatalnog razvitka ključnih subpopulacija stanica koje sudjeluju u antigenski specifičnoj imunosti na sluzničkim površinama crijeva mlade prasadi, daljnji je napredak vidljiv u različitosti obrazaca njihove raspodjele u odjeljcima sluznice jejunuma i postupnom porastu njihove brojnosti, napose između 35. i 49. dana starosti. Tijekom tog razdoblja zabilježen je značajan porast brojnosti djevičanskih, memorijskih i plazma stanica, dok je brojnost pomoćničkih i citotoksičnih T-stanica samo blago porasla između 42. i 49. dana života

Promjene humoralnih i staničnih imunosnih pokazatelja povezane s dobi svinje.

The sequence of development of porcine systemic and local humoral and cellular immunity was analyzed by the age-dependent patterns of total serum immunoglobulin (Ig) levels, responsiveness of peripheral blood lymphocytes (PBL) to common mitogens (phytohemagglutinin, PHA; concanavalin A, ConA; poke-weed mitogen, PWM), or allogeneic PBL in a mixed lymphocyte culture (MLC), and the expression/distribution patterns of intestinal mucosal immune cell subsets, in order to establish the basic immune parameters for an assessment of immunocompetence in clinically normal pigs. Thus, we surveyed the species-related physiological values of these parameters in different age/technological categories, comprising infant (suckling and weaned pigs) and adult (gilts, sows, and boars) swine, kept in intensive rearing conditions. The highest level of total Igs was determined in neonatal pigs (43.5 ± 4.6 g/L), and this value was significantly higher (P<0.001) than that in weaned pigs (12.1 ± 1.5 g/L). Among adult swine, the highest level of total Igs was recorded in sows (32.0 ± 3.1 g/L), and this was much higher (P<0.001) than that found in gilts (25.1 ± 3.5 g/L) or boars (21.2 ± 5.0 g/L). The reactivity of PBL in neonatal pigs decreased by 60-70% compared to weaned pigs, regardless ofthe stimulator applied. In adult swine, the strongest reactivity of PBL, except to PHA, was determined in sows. Histomorphometric analyses showed that CD45RA+, CD45RC+ and IgA+ cells in sections of the jejunum and ileum were significantly higher in weaned pigs (P<0.05) compared to neonatal pigs. The immune parameters obtained for a sample of the swine population in Croatia may serve as a basis for further research on porcine systemic and local (intestinal) immune responsiveness regarding (i) differences among breeds, (ii) the influence of paragenetic factors, (iii) the impact of microbial etiology diseases, particularly those accompanied by immunosuppression, and (iv)the validation of specific/nonspecific immunomodulation.Slijed razvitka sustavne i lokalne humoralne i stanične imunosti u svinje analiziran je s pomoću dobno ovisnih promjena u razinama serumskih imunoglobulina (Ig), odgovorima limfocita periferne krvi (LPK) na uobičajene mitogene (fitohemaglutin, PHA; konkanavalin A, ConA; poke-weed mitogen, PWM) ili specifični antigen (alogenske LPK u miješanoj kulturi limfocita, MKL), te u obrascima ekspresije/distribucije subpopulacija imunosnih stanica u sluznici crijeva radi utvrđivanja temeljnih imunosnih pokazatelja za procjenu imunosne kompetencije u klinički normalnih svinja. Stoga smo istražili za vrstu specifične fiziološke vrijednostitih pokazatelja u različitih dobnih, odnosno tehnoloških kategorija, koje su uključivale mladu prasad (sisančad i odbijenike) i odrasle svinje (nazimice, krmače i nerastove) držane u uvjetima intenzivnog uzgoja. U neonatalne prasadi utvrđema je najviša razina ukupnih Ig (43,5 ± 4,6 g/L), i ta je vrijednost bila značajno viša (P<0,001) od one u odbijene prasadi (12,1 ± 1,5 g/L). U odraslih svinja, najviša razina ukupnih Ig zabilježena je u krmača (32,0 ± 3,1 g/L) i bila je mnogo viša (P<0,001) od onih utvrđenih u nazimica (25,1 ± 3,5 g/L) i nerastova (21,2 ± 5,0 g/L). Reaktivnost LPK u neonatalne prasadi bila je snižena za 60 - 70% u odnosu na onu zabilježenu u odbijene prasadi bez obzira na primijenjeni stimulator. U odraslih svinja, najjača je reaktivnost LPK, osim na PHA, utvrđena u krmača. Histomorfometrijske analize pokazale su da su CD45RA+, CD45RC+ i IgA+ stanice u dijelovima jejunuma i ileuma značajno brojnije u odbijene prasadi (P<0,05) u usporedbi s vrijednostima u neonatalne prasadi. Dobiveni imunosni pokazatelji na uzorku populacije svinja u Hrvatskoj mogu poslužiti kao temelj za dalja istraživanja njihovog sustavnog i lokalnog (crijevnog) imunosnog odgovora s obzirom na: (I) različitosti među pasminama, (II) utjecaje paragenetičkih činitelja, kao što su uvjeti uzgoja/držanja, način prehrane, te ambijentalni i okolišni stresori, (III) učinke bolesti mikrobne etiologije, posebice onih povezanih s imunosupresijom, kao i na (IV) vrednovanje specifične/nespecifične imunomodulacije

Vrijednosti hematoloških pokazatelja u pasa liječenih supkonjunktivalnom primjenom staničnog alografta.

The cornea, as a source for obtaining stem cells, is a good medium for their use in veterinary ophthalmology. In this research, we used dogs which had been diagnosed with extensive, chronic thinning of the central cornea (vertex corneae) generated due to complicated mechanical damage to the corneae pannosa. The goal of this study was to test whether subconjuctival application of limbal stem cells allografts had any influence on haematology parameters in peripheral blood. The animals were divided into three experimental groups regardless of breed, sex and age, and each group comprised 7 dogs. Group A consisted of clinically healthy dogs (control), in group B there were dogs who had had injuries treated by a conventional ophthalmological approach in veterinary medicine, and group C in which corneal injuries were treated using subconjuctival cell allografts. Blood samples were taken four times during the experiment from all animals for haematological analysis. Transplantation of limbal stem cell allografts did not affect the physiological haematology parameters.Rožnica, kao izvor matičnih stanica, dobar je medij za njihovu uporabu u veterinarskoj oftalmologiji. U ovom istraživanju koristili smo pse kojima su dijagnosticirana opsežna, kronična stanjivanja središnjeg dijela rožnice, posljedica mehaničkih oštećenja, dodatno komplicirana upalnim procesima. Cilj istraživanja bio je ispitati utjecaj supkonjunktivalne primjene limbalnog staničnog alografta na hematološke pokazatelje u perifernoj krvi pacijenata. Životinje su bile podijeljene u tri pokusne skupine, bez obzira na pasminu, spol i dob. U svakoj skupini bilo je sedam pasa. U skupini A bili su klinički zdravi psi (kontrolna skupina), u skupini B bili su psi kojima su ozljede obrađene konvencionalnim oftalmološkim pristupom, a psima u skupini C oštećenja rožnice bila su liječena supkonjunktivalnom primjenom staničnog alografta. Četiri puta tijekom istraživanja svim su životinjama uzeti uzorci periferne venske krvi za hematološke pretrage. Supkonjunktivalna primjena staničnog alografta nije utjecala na promjenu vrijednosti hematoloških pokazatelja u obrađivanih pasa

Identifikacija, lokalizacija i kvantifikacija subpopulacija crijevnih imunosnih stanica prasadi tijekom prvih sedam tjedana postnatalnog razvitka.

By using immunohistology and digital image analysis for histomorphometry, we investigated the influence of porcine postnatal development on distribution and quantitative patterns of naïve/memory lymphoid cell subsets (CD45RA+, CD45RC+, respectively), helper/cytotoxic T cell subsets (CD4+, CD8+, respectively) as well as of IgA+ plasma cells in the gut-associated lymphoid tissues (GALT) of pigs reared under intensive conditions during the first 7 weeks of life. Current research on the postnatal ontogenesis/maturation of porcine small intestinal mucosal immune system have shown that newborn pigs are immunologically rather immature and, thus, totally dependent on passively acquired immunity. Their jejunal mucosa almost lacks immune cells, with the exception of a low number of CD45RA+ lymphoid cells (1.25×10-5) at Day 0 post partum. A very few CD45RC+ lymphoid cells (8.79×10-6 ) appeared at Day 7, followed by a similar number of IgA+ plasma cells (7.65×10-6) which were observed at Day 14. Such first signs of the postnatal development of both innate and adaptive immunity by identification/localization of tested cell subsets residing porcine GALT, i e. jejunal mucosal sites are proceeded by a lag period of three weeks until the appearance of low quantities of CD4+ (3.62×10-5) and CD8+ (3.13×10-5) T cells at Day 35 after birth. After that phase of early postnatal development of the crucial cell subsets participating in the antigen-specific immunity on the gut mucosal surfaces of young pigs, further progress was visible through their different distribution patterns within the jejunal mucosa compartments, and a gradual increase in their numbers, particularly between Day 35 and Day 49 of age. A significant increase was recorded within that period in the numbers of naïve, memory and plasma cells, whereas the number of helper and cytotoxic T cells only slightly increased between Day 42 and Day 49 of life.Pomoću imunohistoloških i histomorfometrijskih analiza računalnom obradom slike istraživali smo utjecaj postnatalnog razvitka u svinje na distribucijske i kvantitativne pokazatelje subpopulacija djevičanskih/ memorijskih limfoidnih stanica (CD45RA+ odnosno CD45RC+), pomoćničkih/citotoksičnih T-stanica (CD4+ odnosno CD8+), kao i za IgA+ plazma stanice u limfatičkim tkivima probavnog sustava (LTPS) prasadi uzgajane u intenzivnim uvjetima tijekom prvih 7 tjedana života. Istraživanje postnatalnog razvitka/sazrijevanja imunosnog sustava sluznice tankoga crijeva svinje pokazalo je da je neonatalna prasad imunološki prilično nezrela, pa je stoga u potpunosti ovisna o pasivno stečenoj imunosti. U sluznici njihovog jejunuma gotovo potpuno nedostaju imunosne stanice, s izuzetkom malobrojnih CD45 RA+ limfoidnih stanica (1,2510–5) 0. dana nakon prasenja. Sedmog dana post partum pojavljuje se nešto malo CD45RC+ limfoidnih stanica (8,7910-6), a potom se 14. dana mogu identificirati malobrojne IgA+ plazma stanice (7,650-6). Ovi prvi znakovi postnatalnog razvitka urođene i stečene imunosti, temeljem identifi kacije/lokalizacije subpopulacija istraživanih stanica koje naseljavaju LTPS svinje, odnosno sluznicu jejunuma, nastavljaju se nakon razdoblja od tri tjedna do pojavljivanja malobrojnih CD4+ (3,6210-5) i CD8+ (3,13 10-5) T-stanica 35. dana nakon prasenja. Nakon ove faze ranog postnatalnog razvitka ključnih subpopulacija stanica koje sudjeluju u antigenski specifičnoj imunosti na sluzničkim površinama crijeva mlade prasadi, daljnji je napredak vidljiv u različitosti obrazaca njihove raspodjele u odjeljcima sluznice jejunuma i postupnom porastu njihove brojnosti, napose između 35. i 49. dana starosti. Tijekom tog razdoblja zabilježen je značajan porast brojnosti djevičanskih, memorijskih i plazma stanica, dok je brojnost pomoćničkih i citotoksičnih T-stanica samo blago porasla između 42. i 49. dana života

Supkonjunktivalna primjena alogeničnih limbalnih stanica u pasa s poremećajima rožnice.

Limbal stem cells play a crucial role in maintaining the integrity of the corneal surface in a healthy condition or after injury through corneal renewal and repair. In pathologic conditions these cells could be replenished with cultivated allogenic limbal cells. In this investigation, limbal stem cells from small fragments of donor tissue were cultivated in vitro for treatment of corneal lesions in dogs. Fourteen dogs were divided into two groups of seven animals each: a group of dogs with corneal lesions treated using the classical veterinary ophthalmology approach, and a group of dogs with corneal lesions treated with the application of cultivated allogenic limbal cells. Regardless of the size and location of the corneal lesions, after 30 days in the group of dogs with corneal lesions treated with the application of cultivated allogenic limbal cells ophthalmological examination showed no signs of any eye disorder except corneal edema (14.29 %). In the group of dogs with corneal lesions cured using the classical veterinary ophthalmology approach, 30 days after the beginning of treatment ophthalmological examination showed 42.86 % mild/incisional blepharospasm, 85.71 % secretion, 100 % observable conjuctival congestion, 14.29 % eye liquor dimming, 85.71 % corneal edema and 85.71 % irritation. After application of cultivated allogenic limbal cells, corneal lesions were completely healed 15 days earlier than the lesions treated with conventional ophthalmological therapy. Allogenic limbal cells were capable of restoring corneal clarity with no development of ocular complications.Limbalne matične stanice igraju ključnu ulogu u održavanju integriteta površine rožnice u zdravom stanju ili nakon ozljede, kroz obnavljanje i popravak rožnice. U patološkim stanjima te se stanice mogu nadomijestiti s uzgojenim alogeničnim limbalnim stanicama. U ovom istraživanju limbalne matične stanice iz malih fragmenata tkiva donora uzgojene su in vitro radi liječenja ozljeda rožnice u pasa. Četrnaest pasa bilo je podijeljeno u dvije skupine od sedam životinja: skupina pasa s ozljedama rožnice liječenim klasičnim veterinarskim oftalmološkim pristupom i skupina pasa s ozljedama rožnice liječenim primjenom in vitro uzgojnih alogeničnih limbalnih stanica. Neovisno o veličini i smještaju lezije rožnice, deset dana nakon primjene stanica, oftalmološki pregled je pokazao 80% manje izražene simptome blefarospazma, 85% smanjenu sekreciju, 43% manje uočljivu konjunktivalnu kongestiju, 31% manji edem rožnice i 55% smanjenu iritaciju u usporedbi s psima liječenim klasičnim oftalmološkim pristupom, bez znakova zamućenja očne vodice ili priraslica. Nakon primjene uzgojeni alogeničnih limbalnih stanica, lezije rožnice u potpunosti su bile izliječene 15 dana ranije nego lezije liječene konvencionalnim oftalmološkim načinom. Supkonjunktivalna primejna limbalnih stanica omogućuje potpunu regeneraciju ozljeda rožnice nakon 30 dana bez obzira na veličinu i opseg defekta. Alogenične limbalne stanice sposobne su obnoviti prozirnost rožnice bez razvoja komplikacija. Iako su postignuti rezultati bili ohrabrujući, potrebna su daljnja istraživanja za optimizaciju protokola liječenja

Vrijednosti hematoloških pokazatelja u pasa liječenih supkonjunktivalnom primjenom staničnog alografta.

The cornea, as a source for obtaining stem cells, is a good medium for their use in veterinary ophthalmology. In this research, we used dogs which had been diagnosed with extensive, chronic thinning of the central cornea (vertex corneae) generated due to complicated mechanical damage to the corneae pannosa. The goal of this study was to test whether subconjuctival application of limbal stem cells allografts had any influence on haematology parameters in peripheral blood. The animals were divided into three experimental groups regardless of breed, sex and age, and each group comprised 7 dogs. Group A consisted of clinically healthy dogs (control), in group B there were dogs who had had injuries treated by a conventional ophthalmological approach in veterinary medicine, and group C in which corneal injuries were treated using subconjuctival cell allografts. Blood samples were taken four times during the experiment from all animals for haematological analysis. Transplantation of limbal stem cell allografts did not affect the physiological haematology parameters.Rožnica, kao izvor matičnih stanica, dobar je medij za njihovu uporabu u veterinarskoj oftalmologiji. U ovom istraživanju koristili smo pse kojima su dijagnosticirana opsežna, kronična stanjivanja središnjeg dijela rožnice, posljedica mehaničkih oštećenja, dodatno komplicirana upalnim procesima. Cilj istraživanja bio je ispitati utjecaj supkonjunktivalne primjene limbalnog staničnog alografta na hematološke pokazatelje u perifernoj krvi pacijenata. Životinje su bile podijeljene u tri pokusne skupine, bez obzira na pasminu, spol i dob. U svakoj skupini bilo je sedam pasa. U skupini A bili su klinički zdravi psi (kontrolna skupina), u skupini B bili su psi kojima su ozljede obrađene konvencionalnim oftalmološkim pristupom, a psima u skupini C oštećenja rožnice bila su liječena supkonjunktivalnom primjenom staničnog alografta. Četiri puta tijekom istraživanja svim su životinjama uzeti uzorci periferne venske krvi za hematološke pretrage. Supkonjunktivalna primjena staničnog alografta nije utjecala na promjenu vrijednosti hematoloških pokazatelja u obrađivanih pasa

In vitro cultivation of porcine limbal stem cells

Similarly as in other organ structures stem cells are present in cornea residing basal epithelial layer termed palisade of Voight. A growing interest in allografts and xenografts implies a thorough study of regenerative potentials of these cells, as well as a clear description of their patterns in in vitro tissue cultures to be grafted. Recently we have developed a simple method for cultivation of porcine corneal epithelial stem cells obtained by biopsy from the limbal region. Eight enucleated eyes were obtained from four slaughtered pigs. 5 mm2 samples of limbal epithelium were taken by keratotomy method. The primary cultures of these cells showed phenotypic and morphometric characteristics of porcine corneal epithelial cells following May-Grunwald-Giemsa staining. After 5d of sowing they reached 80% of confluence. With the &laquo;Night &amp; Day&raquo; lenses a total confluence was achieved 5d earlier in comparison to the cells that were grown in the secondary cultures. Accordingly, the use of porcine limbal stem cells has potentials in veterinary medicine (as novel approach in reparative/regenerative medicine of pets, horses and selected breeds), but also are in accordance with the extensive studies on the potential use of xenografts, mainly swine tissues/organs, in humans