Orbital angular momentum in optical fibers

Thesis (Ph.D.)--Boston UniversityInternet data traffic capacity is rapidly reaching limits imposed by nonlinear effects of single mode fibers currently used in optical communications. Having almost exhausted available degrees of freedom to orthogonally multiplex data in optical fibers, researchers are now exploring the possibility of using the spatial dimension of fibers, via multicore and multimode fibers, to address the forthcoming capacity crunch. While multicore fibers require complex manufacturing, conventional multimode fibers suffer from mode coupling, caused by random perturbations in fibers and modal (de)multiplexers. Methods that have been developed to address the problem of mode coupling so far, have been dependent on computationally intensive digital signal processing algorithms using adaptive optics feedback or complex multiple-input multiple-output algorithms. Here we study the possibility of using the orbital angular momentum (OAM), or helicity, of light, as a means of increasing capacity of future optical fiber communication links. We first introduce a class of specialty fibers designed to minimize mode coupling and show their potential for OAM mode generation in fibers using numerical analysis. We then experimentally confirm the existence of OAM states in these fibers using methods based on fiber gratings and spatial light modulators. In order to quantify the purity of created OAM states, we developed two methods based on mode-image analysis, showing purity of OAM states to be 90% after 1km in these fibers. Finally, in order to demonstrate data transmission using OAM states, we developed a 4-mode multiplexing and demultiplexing systems based on free-space optics and spatial light modulators. Using simple coherent detection methods, we successfully transmit data at 400Gbit/s using four OAM modes at a single wavelength, over 1.1 km of fiber. Furthermore, we achieve data transmission at 1.6Tbit/s using 10 wavelengths and two OAM modes. Our study indicates that OAM light can exist, and be long lived, in a special class of fibers and our data transmission demonstrations show that OAM could be considered an additional degree of freedom for data multiplexing in future optical fiber communication links. Our studies open the doors for other applications such as micro-endoscopy and nanoscale imaging which require fiber based remote delivery of OAM light

The plus-hybrid effect on the grain yield of two ZP maize hybrids

Bozinovic S., J.Vancetovic, M.Babic, M.Filipovic and N.Delic (2010): The plus-hybrid effect on the grain yield of two ZP maize hybrids-Genetika, Vol 42, No. 3,475 -484. The combined effect of cytoplasmic male sterility and xenia on maize hybrid traits is referred to as the plus-hybrid effect. Two studied ZP hybrids differently responded to this effect for grain yield. All plus-hybrid combinations of the firstly observed hybrid had a higher yield than their fertile counterparts, but not significantly, while only one combination of the second hybrid positively responded, also without statistical significance. It seems that the observed effect mostly depended on the genotype of the female component

Life-saving percutaneous coronary interventions on the unprotected left main coronary artery in patients with acute coronary syndrome in the catheterization laboratory without cardiosurgical back-up

Introduction. The optimal revascularization strategy for unprotected left main coronary disease (ULMCD) is the subject of ongoing debate and patients with ULMCD still represent a challenge for interventionalist, especially in the setting of an acute coronary syndome (ACS). Case report. We presented two cases of percutaneous treatment of ULMCD in the settings of ACS (ST Segment Myocardial Infarction and Non ST Segment Myocardial Infarction - STEMI and NSTEMI) in a catheterization laboratory without back-up of cardiosurgical department. Both patients were hemodynamically unstable with clinical signs of cardiogenic shock. Coronary angiography revealed left main thromobosis and using intra-aortic balloon pump as hemodynamic support primary angioplasty procedures were performed. Immediately after the procedures the patients hemodynamically improved and remained stable till discharge from hospital. Conclusion. Percutaneous coronary intervention (PCI) has become the most common strategy of revascularization in ACS patients with ULMCD and is generally preferred in patients with multiple comorbidities and/or in very unstable patients. In cases with no cardiosurgical departments PCI is an inevitable, bail-out, life saving procedure

Coronary flow and hemorrhagic complications after alteplase and streptokinase administration in patients with acute myocardial infarction

Background/Aim. Up-to-date treatment of acute myocardial infarction (AIM) has been based on as early as possible establishment of circulation in ischemic myocardium whether by the use of fibrinolythic therapy and/or urgent coronary intervention which significantly changes the destiny of patients with AMI, but also increases the risk of bleeding. The aim of this study was to compare coronary flow and bleeding complications in patients with acute myocardial infarction with ST-elevation (STEMI) after administration of alteplase or streptokinase. Methods. The study included 254 patients with STEMI. The group I (n = 174) received streptokinase, and the group II (n = 80) received alteplase. We followed frequency of complications such as bleeding and hypotension in the investigated groups of patients, based on the TIMI classification of bleeding, as well as the transience of infarction artery in accordance with TIMI flow. Results. The patients with myocardial infarction after administration of alteplase had statistically significantly higher coronary flow (TIMI- 3), 72.5% as compared to the patients who received streptokinase, 39.2%. Hypotension as complication of fibrynolythic therapy administration occurred in a significantly higher percentage in the group of patients who received streptokinase. There was no statistically significant difference in the appearance of major bleeding in the groups of patients who received streptokinasis and alteplase (6.9% and 7.5%, respectively). Also, there was no difference in the appearance of minor and minimal bleeding among the investigated groups of patients. Conclusion. It was shown that alteplase in a higher number of patients provided TIMI-3 coronary flow as compared to streptokinese. In comparison with streptokinase, a combination of alteplase, enoxaparin and double antiplatelet therapy enabled earlier achievement of coronary flow through previously blocked coronary artery that was more complete (higher frequency of TIMI-3 flow). There were no statistically significant difference in frequency of bleeding, first of all major bleeding, between the groups treated by alteplase and streptokinase

Echocardiographic estimation of acute haemodynamic response during optimization of multisite pace-maker using different pacing modalities and atrioventricular delays

Background/Aim. Cardiac resynchronization therapy (CRT) improves ventricular dyssynchrony and is associated with an improvement in symptoms, quality of life and prognosis in patients with severe heart failure and intraventricular conduction delay. Different pacing modalities produce variable activation patterns and may be a cause of different haemodynamic changes. The aim of our study was to investigate acute haemodynamic changes with different CRT configurations during optimization procedure. Methods. This study included 30 patients with severe left ventricular systolic dysfunction and left bundle branch block with wide QRS (EF 24.33 ± 3.7%, QRS 159 ± 17.3 ms, New York Heart Association III/IV 25/5) with implanted CRT device. The whole group of patients had severe mitral regurgitation in order to measure dP/dt. After implantation and before discharge all the patients underwent optimization procedure guided by Doppler echocardiography. Left and right ventricular pre-ejection intervals (LVPEI and RVPEI), interventricular mechanical delay (IVD) and the maximal rate of ventricular pressure rise during early systole (max dP/dt) were measured during left and biventricular pacing with three different atrioventricular (AV) delays. Results. After CRT device optimization, optimal AV delay and CRT mode were defined. Left ventricular pre-ejection intervals changed from 170.5 ± 24.6 to 145.9 ± 9.5 (p < 0.001), RVPEI from 102.4 ± 15.9 to 119.8 ± 10.9 (p < 0.001), IVD from 68.1 ± 18.3 to 26.5 ± 8.2 (p < 0.001) and dP/dt from 524.2 ± 67 to 678.2 ± 88.5 (p < 0.01). Conclusion. In patients receiving CRT echocardiographic assessment of the acute haemodynamic response to CRT is a useful tool in optimization procedure. The variability of Doppler parameters with different CRT modalities emphasizes the necessity of individualized approach in optimization procedure

Kombinovana S1-TC-RRS pri korišćenju CMS-a i dihaploida kod kukuruza

Herein, we present the combined S1-HS-RRS method using inbred testers (S1-TC-RRS) as a long-term maize breeding program, which increases the frequency of favorable alleles and maintains genetic variability in two genetically opposite populations. The method improves two different genetic sources simultaneously, where S1 families, developed by selfing phenotypically superior plants from both breeding populations are crossed with opposite inbred testers for specific combining ability selection, accompanied by selection of S1 families per se. A certain percentage of the evaluated S1 families is used for the next TC-RRS selection cycle. Maternal haploids from the selected S1 lines of each cycle of S1-TC-RRS can serve to produce elite 100% homozygous inbred lines (dihaploids) in a short time, which decreases the time and expenses of the selection cycle and influence the efficiency of seed production, as well as, variety protection rights. This elite lines than can be converted to CMS versions (paternal haploids), for the seed production, which lowers the costs of it.Prestavlja se kombinovani S1-HS-RRS metod uz korišćenje inbred testera (S1-TCRRS), kao dugoročni program u oplemenjivanju kukuruza, koji povećava frekvenciju poželjnih alela i održava genetičku varijabilnost dve genetički opozitne populacije. Metodom se u isto vreme popravljaju dva genetički opozitna izvora, gde se S1 familije, dobijene samooplodnjom fenotipski superiornih biljaka iz obe populacije, ukrštaju sa opozitnim inbred testerom radi selekcije na posebne kombinacione sposobnosti, uz istovremenu selekciju S1 familija per se. Određen procenat ispitivanih S1 familja se koristi za sledeći TC-RRS ciklus selekcije. Uz pomoć metode majčinskih haploida, iz odabranih S1 linija svakog S1-TC-RRS ciklusa mogu se dobiti 100% homozigotne elitne inbred linije (dihaploidi) za kratko vreme, što smanjuje vreme i troškove selekcionog ciklusa, a utiče na efikasnost semenske proizvodnje i zaštitu oplemenjivačkih prava. Ove elitne inbred linije mogu se prevesti na cms verziju (ocinski haploidi), što smanjuje troškove u semenskoj proizvodnji

Primena novih tehnologija u oplemenjivanju kukuruza u Institutu za kukuruz „Zemun Polje"

Institut za kukuruz "Zemun Polje" (MRIZP) razvija program oplemenjivanja kukuruza vise od 75 godina. Stvaranje novih hibrida, koji po svojim najvažnijim agronomskim osobinama prevazilaze hibride prethodne generacije predstavlja primarni zadatak svakog oplemenjivača kukuruza. Prisustvo ZP hibrida kukuruza na tržištima Republike Srbije, ali i u inostranstvu, zahteva stvaranje hibrida za različite agroklimatske uslove, kao i za razlicite namene. Spajanje različitih naučno istraživačkih disciplina dovelo je do ubrzanja i povećanja tačnosti procesa oplemenjivanja kukuruza, a samim tim i do smanjenja trajanja ciklusa oplemenjivanja kukuruza u svetu do pet, a u MRIZP-u na 6-7 godina. Od 2014. godine MRIZP uspešno primenjuje program dvostrukih haploida (DH) u oplemenjivanju. Primenom takvog pristupa storeno je više od 13.000 novih DH inbred linija. Kao rezultat primene DH tehnologije, registrovan je prvi hibrid ZP 4019. MRIZP intenzivno radi na karakterizaciji najelitnijeg materijala uz pomoc SNP (Single Nucleotide Markers) markera koristeći 25k SNP Ilumina Infinium Array. Na ovaj način je ostvaren najprecizniji uvid u germplazmu oplemenjivača, odnosno odredjivanjem genetičke udaljenosti (GD). Uz pomoć GD vrednosti povećana je verovatnoća dobijanja superiornih inbred linija i hibrida kukuruza. Već dve sezone MRIZP je započeo visokoinformativnu fenotipizaciju u polju (HTFP), koristeći RGB i multispektralne kamere zasnovane na dronovima za ekstrakciju i vizuelizaciju podataka po parceli. U ovoi fazi istražujemo mogućnost zamene ručnih merenja (kao što je broj i poleganje biljaka), dok je naš konačni cilj da upotrebimo HTFP za donošenje presudnih odluka za hibrid u našim programima oplemenjivanja

Population structure and diversity in former ZP maize breeding program assessed with SNP markers

Maize breeding in Maize research institute “Zemun Polje” was conducted for more than 75 years resulting in the creations of numerous maize hybrids with superior traits and performance. The source breeding material used in the breeding programs was very diverse and varied from the domestic landraces to the introduced inbred lines. This resulted in a very diverse and complex structure of the breeding pools used in commercial maize breeding in “Zemun Polje” Institute. As genetic material in this study, 24 maize inbred lines of different origin, heterotic and maturity goups were selected were selected from the 3rd and 4th cycle of breeding in Maize research institute “Zemun Polje”. These are inbreds that were commonly used in breeding programs during the 1980s and were parental components of most important commercial maize hybrids. The genotyping was performed using a Maize 25k Infinium array. The neighbor-joining cladogram, PcoA and Structure were used to analyze the genetic structure and diversity of the panel. Population structure analysis of the panel initially showed a clear divide between Lancaster and Non-Lancaster inbred lines, revealing the dominant heterotic pattern in the breeding program. Further analysis with an increased number of population (k) showed a more complex structure of the non-Lancaster group of inbred lines with best number of ancestral population being k=5. The average genetic distance in the panel was 0,385, ranging from 0,039 to 0,544, with paternal inbreds in most of commercial hybrids being the most distant ones. The genotyping results of the Zemun Polje maize panel were further merged with DROPS European panel of 247 dent maize inbred lines in order to view the results of the diversity analysis of the Zemun Polje panel from a broader perspective

Biochemical and physical kernel properties of a standard maize hybrid in different TopCross (TM) Blends

A pilot experiment was undertaken in order to examine high oil populations of maize (Zea mays L.) to be used as pollinators in TopCross blends with commercial ZP341 standard hybrid. Five high oil populations (HOPs) from the Maize Research Institute (MRI) gene bank were chosen for this research, according to their high grain oil content, synchrony between silking of ZP341 and anthesis of the populations and good agronomic performances in 2012. Selfing of ZP341 and HOPs, as well as crosses of ZP341 cmsS sterile x HOPs were carried out in 2013. Oil content, fatty acid composition, protein and tryptophan content, and physical characteristics of the obtained kernels were measured. Four HOPs showed significant positive influence on the oil content in the TopCrosses (TC), 16.85 g kg(-1) on average. Oleic acid, which is the principal monounsaturated fatty acid, was significantly lower in all HOPs and all TCs, while selfed ZP341 had almost twice the average value typical for standard maize. However, this decrease in TCs was in a narrow range from 1 % (in TC-3) to 5 % (in TC-4) and the oleic content of TCs was on average higher by 60 % compared to the typical standard maize. Different favorable and unfavorable significant changes were detected in fatty acid compositions, protein and tryptophan contents and physical kernel properties for each potential TC combination. Results indicate differences in gene effects present in different TC combinations and underscore the need to examine each potential TC blend by conducting similar simple experiments

Agronomic traits of QPM maize hybrids adapted to temperate regions

In this paper agronomic characteristics of quality protein maize (QPM) hybrids adapted to temperate regions created in Maize Research Institut Zemun Polje are presented. Hybrid ZPQPM13 showed favorable traits for growing in these regions, and its grain yield was at the level of one of the leading ZP hybrids - ZP 606. However, grain moisture of this hybrid was 3% higher than that of ZP 606, pointing out to the tropical origin of its parental inbred lines. Namely, mother was obtained from F1 cross between tropical and adapted lines, and father by marker assisted selection (MAS) from QPM line of tropical origin that was crossed and twice backcrossed with a commercial ZP line. In the future, in order to obtain even more adapted QPM hybrids, MAS program will continue with all the best commercial ZP inbred lines of all FAO groups