Lower bounds for the first eigenvalue of the Laplacian with zero magnetic field in planar domains

We study the Laplacian with zero magnetic field acting on complex functions of a planar domain Ω, with magnetic Neumann boundary conditions. If Ω is simply connected then the spectrum reduces to the spectrum of the usual Neumann Laplacian; therefore we focus on multiply connected domains bounded by convex curves and prove lower bounds for its ground state depending on the geometry and the topology of Ω. Besides the area, the perimeter and the diameter, the geometric invariants which play a crucial role in the estimates are the fluxes of the potential one-form around the inner holes and the distance between the boundary components of the domain; more precisely, the ratio between its minimal and maximal width. Then, we give a lower bound for doubly connected domains which is sharp in terms of this ratio, and a general lower bound for domains with an arbitrary number of holes. When the inner holes shrink to points, we obtain as a corollary a lower bound for the first eigenvalue of the so-called Aharonov-Bohm operators with an arbitrary number of poles

The methodical approach to epic folk poems with gospel motives

У овом раду су обрађене епске народне песме с јеванђељским, хришћанским мотивима које је српски народ вековима, поред паганских мотива, највише у њих уграђивао исказујући тако своје погледе на свет и на живот. Кроз њих је поимао шта је добро, а шта зло; шта је правда, а шта је неправда. Кроз њих се огледа живот народни, његова мука и патња, јунаштво, радост и лепота, али и чежња за слободом и жртва за њу. Захваљујући тим јеванђељским мотивима генерације људи су се управо преко епских народних песама упознале са Јеванђељем. У почетку хришћанства, историјски услови прогона хришћана довели су до тога да се Јеванђеље (Εσαγγέλιον) ширило мање по синагогама, а много више по приватним кућама широм Римског царства. На сличан начин, прогони у турско доба довели су да се код српског народа, као на почетку хришћанске историје, Јеванђеље шири у приватним домовима кроз епске народне песме. Последице оваквог историјског и културног приступа су евидентне и ми смо покушали да их покажемо кроз овај рад. Тако на пример у песмама где год има јеванђељских мотиванеупоредиво је мање крви, мржње, бритких сабљи, тешких буздована, поломљених јуначких костију, а више је љубави, правде, милосрђа, покајања, праштања и поштења. Многипроучаваоци српске народне књижевности нису узимали у обзир православну веру и њен утицај,на песму, на живот нашег народа, његовог делања и стварања. Далеко више су проучавани митолошки и пагански мотивинего јеванђељски.Неки су чак тврдили да и нема толико блискости између Јеванђеља и епске песме што је и разлог да се, и поред уложеног труда, није долазило до озбиљних и утемељених резултата.Уколико се и наглашавао хришћански утицај, он се обично сводио на проналажење мотива Старог завета у њима, а никако, или сасвим ретко Новог завета. Стога, ова дисертација полази од указивања на поменути проблем до налажења праве мере између ових крајности. Наиме, специфичност јеванђељских мотива огледа се у њиховој двострукој семантици – књижевној и теолошкој. Паралела између епске поезије и Јеванђеља је уочена иовај рад смо доживели као изазов спајања методике, књижевности и наставе веронауке, са циљемда помогне ученицима да разумеју не само верско градиво, већ да, управо помоћу тог знања, разумеју и друге предмете који ће им помагати да примене научено градиво у свакодневном животу...This work is about Serbian epic poetry with evangelical, Christian motives, which were embedded throughout the centuries, alongside pagan motives, into the epic poetry. In this way Serbian people have expressed their outlook on world and life. Through this poetry they also perceived what was right and what was wrong; what was just and what was unjust. They expressed the way of life at the time and people‘s troubles and sufferings, heroism, joy and beauty, longing for freedom and sacrificing for it.Thanks to these evangelical motives, the following generations were introduced to the Gospel. At the beginning of Christianity, historical circumstances of the persecution of Christians led to the fact that the Gospel (Εσαγγέλιον) was heard at private houses alongside Roman Empire, much more than at synagogues. In the similar way, during the Turkish reign, Serbian people - just like the early Christians in the Roman Empire- spread the word of the Gospel at private homes through epic poetry. The consequences of this historical and cultural approach are evident, and we tried to distinguish them in this work. For example, wherever evangelical motives are present there is far less blood, hatred, sharp swards, heavy maces, heroes‘ broken bones, and there‘s much more love, justice, charity, repentance, forgiveness and honesty. Many scholars who studied Ser-bian poetry have misunderstood Orthodox religion and its influence on people‘s lives and work through poetry. They focused more on mythological and pagan motives rather than on evangelical ones. Some even claimed that there‘s no similarity between the Gospel and the epic poetry, which was a reason why no one came to serious conclusions on this subject. Even if they tried to point out Christian influence, it ended up being an Old Testament motive, almost never one from the New Testament. Therefore, this doc-toral dissertation has a starting point at indicating this problem and finding the right ratio between these two extremes. Evangelical motives are specific for their double se-mantics – literal and theological. A parallel between epic poetry and the Gospel has been recognized and this work represents a challenge of joining methods, literature and religious education, with the aim to help students to get to know not only religious ma-terial, but also to understand other subjects, which will help them apply this knowledge in everyday life..

Hybrid photonic-bandgap accelerating cavities

In a recent investigation, we studied two-dimensional point-defected photonic bandgap cavities composed of dielectric rods arranged according to various representative periodic and aperiodic lattices, with special emphasis on possible applications to particle acceleration (along the longitudinal axis). In this paper, we present a new study aimed at highlighting the possible advantages of using hybrid structures based on the above dielectric configurations, but featuring metallic rods in the outermost regions, for the design of extremely-high quality factor, bandgap-based, accelerating resonators. In this framework, we consider diverse configurations, with different (periodic and aperiodic) lattice geometries, sizes, and dielectric/metal fractions. Moreover, we also explore possible improvements attainable via the use of superconducting plates to confine the electromagnetic field in the longitudinal direction. Results from our comparative studies, based on numerical full-wave simulations backed by experimental validations (at room and cryogenic temperatures) in the microwave region, identify the candidate parametric configurations capable of yielding the highest quality factor.Comment: 13 pages, 5 figures, 3 tables. One figure and one reference added; minor changes in the tex

Akumulacija teških metala u Medicago sativa L. i Trifolium pratense L. na kontaminiranom fluvisolu

Recently, heavy metals concentrations increased in some agricultural areas due to the consequences of anthropogenic impacts. The aim of this study was to determine the level of heavy metals (As, Cr, Ni and Pb) in Medicago sativa L. and Trifolium pratense L. grown on fluvisol, in order to obtain information on safety of these nutrients. The total content of Pb, As, Cr and Ni in the samples of fluvisol was above the maximum allowable amount. The content of heavy metals in Medicago sativa L. and Trifolium pratense L. was below the critical and toxic concentrations in all samples originating from contaminated soil. It was concluded that the accumulation of heavy metals in plants did not depend only on the total content in soil, but also the affinity of the plant, and individual and interactive effects of various soil properties. No statistically significant differences in the accumulation of heavy metals between Medicago sativa L. and Trifolium pratense L were observed. It is necessary to further control of heavy metals in the investigated area, in order to prevent their entry into the food chain and provide healthy food.U poslednje vreme povećana je koncentracija teških metala na nekim poljoprivrednim površinama usled antropogenog uticaja. Cilj rada je bio da se utvrdi nivo teških metala (As, Cr, Ni i Pb) u nekarbonatnom aluvijalnom (fluvijanom) zemljištu, te njihova akumulacija u Medicago sativa L. i Trifolium pratense L., radi dobijanja informacije o zdravstvenoj ispravnostinosti ovih hraniva. Ukupan sadržaj ispitivanih teških metala u uzorcima zemljišta bio je iznad maksimalno dozvoljene količine, što znači da svi uzorci analiziranih lokaliteta pripadaju kategoriji kontaminiranog zemljišta. Sadržaj teških metala u Medicago sativa L. i Trifolium pratense L. bio je ispod kritičnih i toksičnih koncentracija, kao i maksimalno dozvoljenih količina u hrani za životinje u svim uzorcima poreklom sa kontaminiranog zemljišta. Konstatovano je da akumulacija teških metala u biljkama nije zavisila samo od ukupnog sadržaja u zemljištu, nego i afiniteta biljke, te individualnog ili interaktivnog dejstva raznih zemljišnih svojstava. Nije bilo značajnih razlika u akumulaciji teških metala izmeću Medicago sativa L. i Trifolium pratense L

Index estimates for free boundary minimal hypersurfaces

We show that the Morse index of a properly embedded free boundary minimal hypersurface in a strictly mean convex domain of the Euclidean space grows linearly with the dimension of its first relative homology group (which is at least as big as the number of its boundary components, minus one). In ambient dimension three, this implies a lower bound for the index of a free boundary minimal surface which is linear both with respect to the genus and the number of boundary components. Thereby, the compactness theorem by Fraser and Li implies a strong compactness theorem for the space of free boundary minimal surfaces with uniformly bounded Morse index inside a convex domain. Our estimates also imply that the examples constructed, in the unit ball, by Fraser–Schoen and Folha–Pacard–Zolotareva have arbitrarily large index. Extensions of our results to more general settings (including various classes of positively curved Riemannian manifolds and other convexity assumptions) are discussed

Studija projekta 'Optimizacija i standardizacija autohtone tehnologije sjeničkog sira sa zaštitom oznake porekla'

Investigations are based on use of natural potentials on the wide region of Sjenica-Pešter highlands. Certain parameters on selected locations are recorded (soil, vegetation, livestock production, technology of milk and cheese production). On selected locations, farms and processing capacities detail researches are carried out relating to soil, artificial and natural grasslands, reproductive and production potential of cattle and sheep, determination of genetic and non-genetic factors affecting milk traits, quantity and quality of milk, proteins, milk fat, lactose, etc., technological and microbiological traits of milk and cheese. Main objectives of this research and development project is to realize scientific -technological solutions in primary livestock production using our own scientific potentials in order to provide increased productivity, increased number of market farmers capable for competitive economy and production on domestic and foreign market with recognized final product with protected geographical origin, in other words - optimization and standardization of native technology of white cheese from Sjenica with protected brand and origin.Istraživanja su zasnovana na korišćenju prirodnih potencijala šireg regiona Sjeničko-pešterske visoravni. U okviru ovih istraživanja obavlja se snimanje i proučavanje određenih parametara na odabranim lokalitetima ( zemljište, vegetacija, stočarstvo, tehnologija mleka i sira). Na odabranim lokalitetima, farmama i preradjivačkim kapacitetima obavljaju se detaljna istraživanja, zemljišta, prirodnih i veštačkih travnjaka i livada, reproduktivnih i proizvodnih potencijala goveda i ovaca, determinacija genetskih i negenetskih faktora na svojstva mlečnosti, kvantitet i kvalitet mleka, proteini, mlečna mast, laktoza i dr.,tehnološka i mikrobiološka svojstva mleka i sira. Osnovni ciljevi ovog istraživačko-razvojnog projekta je da se korišćenjem sopstvenih naučnih potencijala dođe do naučno-tehnoloških rešenja u primarnoj stočarskoj proizvodnji, koja će obezbediti porast produktivnosti, povećanje robnih proizvođača osposobljenih za konkurentnu proizvodnju na domaćem i stranom tržištu sa prepoznatljivim finalnim proizvodom zaštićenog geografskog porekla, odnosno optimizaciju i standardizaciju autohtone tehnologije Sjeničkog sira sa zaštitom oznake porekla

Operationalizing local ecological knowledge in climate change research : challenges and opportunities of citizen science

Current research on the local impacts of climate change is based on contrasting results from the simulation of historical trends in climatic variables produced with global models against climate data from independent observations. To date, these observations have mostly consisted of weather data from standardized meteorological stations. Given that the spatial distribution of weather stations is patchy, climate scientists have called for the exploration of new data sources. Knowledge developed by Indigenous Peoples and local communities with a long history of interaction with their environment has been proposed as a data source with untapped potential to contribute to our understanding of the local impacts of climate change. In this chapter, we discuss an approach that aims to bring insights from local knowledge systems to climate change research. First, we present a number of theoretical arguments that give support to the idea that local knowledge systems can contribute in original ways to the endeavors of climate change research. Then, we explore the potential of using information and communication technologies to gather and share local knowledge of climate change impacts. We do so through the examination of a citizen science initiative aiming to collect local indicators of climate change impacts: the LICCI project (www.licci.eu). Our findings illustrate that citizen science can inspire new approaches to articulate the inclusion of local knowledge systems in climate change research. However, this requires outlining careful approaches, with high ethical standards, toward knowledge validation and recognizing that there are aspects of local ecological knowledge that are incommensurable with scientific knowledge

Brain death and postmortem organ donation: Report of a questionnaire from the CENTER-TBI study

Background: We aimed to investigate the extent of the agreement on practices around brain death and postmortem organ donation. Methods: Investigators from 67 Collaborative European NeuroTrauma Effectiveness Research in Traumatic Brain Injury (CENTER-TBI) study centers completed several questionnaires (response rate: 99%). Results: Regarding practices around brain death, we found agreement on the clinical evaluation (prerequisites and neurological assessment) for brain death determination (BDD) in 100% of the centers. However, ancillary tests were required for BDD in 64% of the centers. BDD for nondonor patients was deemed mandatory in 18% of the centers before withdrawing life-sustaining measures (LSM). Also, practices around postmortem organ donation varied. Organ donation after circulatory arrest was forbidden in 45% of the centers. When withdrawal of LSM was contemplated, in 67% of centers the patients with a ventricular drain in situ had this removed, either sometimes or all of the time. Conclusions: This study showed both agreement and some regional differences regarding practices around brain death and postmortem organ donation. We hope our results help quantify and understand potential differences, and provide impetus for current dialogs toward further harmonization of practices around brain death and postmortem organ donation

Fano resonance engineering in mirror-symmetry-broken THz metamaterials

We introduce a comprehensive approach to the design of mirror-symmetry broken terahertz (THz) metamaterials and present both the simulation and experimental results which show the desired asymmetric Fano resonances and electromagnetic induced transparency (EIT)-like windows. With a full wave simulation, we find these asymmetry-induced resonance modes possess extremely high quality factors and they broaden with increase of the structure asymmetry. This phenomenon arises from the destructive interference of a super-radiative bright mode and a sub-radiative dark mode which can’t be excited directly. Surface current and electric field distributions are analyzed to explain the emergence of these Fano resonances. An intuitive mechanical coupled oscillator model is derived to explain the unique line-shape of such Fano resonances. Moreover, large resonant frequency tuning (50 GHz) of Fano resonance has been demonstrated by temperature induced phase change in liquid crystals. We believe that the Fano resonance in THz metamaterials may serve as a strong building block for passive or active THz elements with potential applications for future detection and sensing systems and devices.The authors would like to thank the UK Engineering and Physical Sciences Research Council (EPSRC) for the support through the Platform Grant for Liquid Crystal Photonics (EP/F00897X/1). Xuefeng Li would like to acknowledge the support from Cambridge Trust.This is the author accepted manuscript. It is currently under an indefinite embargo pending publication by Springer

Variation in Structure and Process of Care in Traumatic Brain Injury: Provider Profiles of European Neurotrauma Centers Participating in the CENTER-TBI Study.

INTRODUCTION: The strength of evidence underpinning care and treatment recommendations in traumatic brain injury (TBI) is low. Comparative effectiveness research (CER) has been proposed as a framework to provide evidence for optimal care for TBI patients. The first step in CER is to map the existing variation. The aim of current study is to quantify variation in general structural and process characteristics among centers participating in the Collaborative European NeuroTrauma Effectiveness Research in Traumatic Brain Injury (CENTER-TBI) study. METHODS: We designed a set of 11 provider profiling questionnaires with 321 questions about various aspects of TBI care, chosen based on literature and expert opinion. After pilot testing, questionnaires were disseminated to 71 centers from 20 countries participating in the CENTER-TBI study. Reliability of questionnaires was estimated by calculating a concordance rate among 5% duplicate questions. RESULTS: All 71 centers completed the questionnaires. Median concordance rate among duplicate questions was 0.85. The majority of centers were academic hospitals (n = 65, 92%), designated as a level I trauma center (n = 48, 68%) and situated in an urban location (n = 70, 99%). The availability of facilities for neuro-trauma care varied across centers; e.g. 40 (57%) had a dedicated neuro-intensive care unit (ICU), 36 (51%) had an in-hospital rehabilitation unit and the organization of the ICU was closed in 64% (n = 45) of the centers. In addition, we found wide variation in processes of care, such as the ICU admission policy and intracranial pressure monitoring policy among centers. CONCLUSION: Even among high-volume, specialized neurotrauma centers there is substantial variation in structures and processes of TBI care. This variation provides an opportunity to study effectiveness of specific aspects of TBI care and to identify best practices with CER approaches