139 research outputs found
Occupational exposure to MRI, risk assessment and protection measures
No full textUvod: Zaposleni, ki delajo v območju naprav za MR slikanje so izpostavljeni različnim oblikam elektromagnetnih polj (EMP), ki se razlikujejo glede na frekvenco in trajanje izpostavljenosti. Za omejitev poklicne izpostavljenosti in varstvo pred zdravstvenimi tveganji zaradi EMP so mednarodne organizacije in odbori izdali različna varnostna priporočila in smernice. Direktiva 2013/35/EU določa specifične mejne vrednosti izpostavljenosti in opozorilne vrednosti za preprečitev posrednih in neposrednih biofizikalnih učinkov na zdravje zaposlenih. Namen: Namen raziskave je bil ugotoviti izpostavljenost zaposlenih, ki opravljajo delo v območju naprav za MR slikanje ter rezultate meritev primerjati z mejnimi in opozorilnimi vrednostmi, ki jih določa direktiva 2013/35/EU. Metode dela: Meritve Bo polja smo izvedli z uporabo merilne naprave Metrolab THM 1176. Za meritve impulznih visokofrekvenčnih polj smo uporabili dva merilna postopka. Z merilno napravo SRM-3006 smo izvedli točkovne meritve impulznih VF EMP v času izvedbe kliničnega protokola. Istočasno smo izvajali še meritve z napravo Narda NBM-550 na fiksnem merilnem mestu. Meritve nizkofrekvenčnega gradientnega magnetnega polja smo izvedli z uporabo merilne naprave ELT 400, ki je bila preko analognega vmesnika priključena na osciloskop. Rezultati: Najvišja vrednost Bo polja v območju izven prostora z MR napravo je bila izmerjena na merilnem mestu št. 2 in je znašala 0,61 mT. Najvišja vrednost Bo polja znotraj območja z MR napravo je bila izmerjena na merilnem mestu št. 10, ki označuje vhod v odprtino naprave in je znašala 1000 mT. Analiza meritev je pokazala, da so bile izpeljane opozorilne vrednosti za dB/dt presežene pri meritvah, ki so bile izvedene v prostoru z MR napravo na merilnih mestih 29 (4,03 T/s) in Y (7,08 T/s). Najvišja vrednost električne poljske jakosti je znašala 22,92 V/m, kar predstavlja 37,57 % opozorilne vrednosti Direktive 2013/35/EU za frekvenčno območje 10-400 MHz. Razprava in zaključek: Na podlagi rezultatov meritev in naših ugotovitev lahko potrdimo, da je poklicna izpostavljenost med rutinskimi postopki na MR oddelku Onkološkega inštituta Ljubljana skladna z mejnimi in opozorilnimi vrednostmi Direktive 2013/35/EU.Introduction: Medical personnel working in the MRI environment are exposed to various forms of electromagnetic fields (EMF) that vary in frequency and duration of exposure. Many international organizations and committees have developed various safety guidelines to limit occupational exposure and provide protection against known adverse health effects of EMF. Directive 2013/35/EU defines specific exposure limit values and the action levels to prevent all known indirect and direct biophysical health effects caused by EMF. Purpose: The purpose of this paper was to assess the occupational exposure to EMF in MRI clinical environment and to verify its compliance with exposure limit values and action levels set by Directive 2013/35/EU. Methods: The measurements of the static magnetic field have been performed using Metrolab THM 1176 measuring device. Two exposure recording systems were used to assess exposure to high frequency RF fields. Spot measurements were performed using SRM-3006. Simultaneously we measured electric field strength of high frequency RF fields on a fixed grid using Narda NBM 550. Exposure to low frequency gradient magnetic fields involved a measuring system of a Narda ELT 400 that was connected to the oscilloscope via analogue output of the probe. Results: The peak value of the Bo fringe field in the area outside the room with the MRI scanner was measured at the measuring spot 2 (0,61 mT). The peak value of the Bo field inside the room with the MRI scanner reached 1000 mT and was measured at the measuring spot 10. The analysis of low frequency gradient magnetic field measurements showed that the derived action levels for dB/dt were exceeded in the proximity of the MRI device during ongoing clinical protocol at two measuring spots. Peak values of dB/dt measured at this two measuring spots reached 4,03 T/s (measuring spot 29) and 7,08 T/s (measuring spot Y). The peak incident electric field strength was measured at 22,92 V/m, which represents 37,57 % of the action value for the frequency range 10-400 MHz. Discussion and conclusion: Based on the results of the measurements and our findings, we can confirm that the occupational exposure during routine clinical procedures at the MRI department of the Oncology Institute of Ljubljana complies with the exposure limit values and action levels set by Directive 2013/35/EU
Strategy of implants suitability testing in magnetic resonance imaging with patients through diagnostics in Slovenia
No full textUvod: Magnetno resonančno slikanje je dandanes nepogrešljiva diagnostična metoda. Odlikuje jo odlična kontrastna ločljivost med mehkimi tkivi in odsotnost ionizirajočega sevanja. Kljub veliki uporabnosti magnetno resonančnega slikanja pa lahko slednje v določenih primerih predstavlja tudi nevarnost za pacienta. Obstajajo primeri, v katerih obravnavana oseba ne sme opraviti preiskave na magnetu. Vsi vsadki, na katere vpliva magnetno polje in električni tok, ne smejo priti v bližino magnetno resonančnega polja. Nikoli ne smemo predvidevati stopnjo varnosti predmeta, če le ta ni določena in dokumentirana. Obstaja veliko potencialnih nevarnosti: Nevarnosti magnetnega polja izvirajo iz statičnega magnetnega polja, radio-frekvenčnega (RF) elektromagnetnega polja in gradienta magnetnega polja. Namen: Namen našega diplomskega dela je ugotoviti, na kakšen način radiološki inženirji preverjajo ustreznost implantatov za MR slikanje, pri pacientih po diagnostikah v Sloveniji. Metode dela: Teoretični del diplomske naloge sloni na sistematičnem pregledu strokovnih člankov objavljenih na spletu, tujih priporočil o MR varnosti ter knjižnih virov na temo magnetno resonančne diagnostike. Za potrebe empiričnega dela diplomske naloge smo s pomočjo programa 1ka izdelali anketni vprašalnik. Vprašanja zajemajo področje obravnave šestih različnih vrst vsadkov, področje obravnave vsadka neznanega izvora ter področje MR varnosti na oddelku. Anketni vprašalnik smo poslali ekipam na MR diagnostikah po Sloveniji. Podatke smo obdelovali z Microsoft Excel Office ter s programom za analizo podatkov, ki ga vsebuje spletni program 1ka. Rezultati: Vseh 100% radioloških inženirjev, ki so reševali vprašalnik, je pri svojem delu obravnavalo pacienta z ortopedskim vsadkom in pacienta z intravaskularno žilno opornico. 86% oseb je obravnavalo pacienta z vstavljenim srčnim spodbujevalnikom, 73% pacienta z intrakranialnim klipom anevrizme, 95% pacienta z umetno srčno zaklopko ter 82% pacienta s kohlearnim (polževim) vsadkom. 68% radioloških inženirjev je obravnavalo pacienta z vstavljenim vsadkom neznanega izvora (vsadek brez dokumentacije). Nadaljevanje vprašalnika je bilo pogojeno z odgovori na prvo vprašanje. Razprava in zaključek: Po analizi rezultatov smo ugotovili, da je delo radioloških inženirjev na MR diagnostikah po Sloveniji, primerljivo s smernicami iz tujih priporočil. Delo se ujema s smernicami na področju izvajanja ukrepov za zmanjšanje popačenj zaradi vsadka, področju obravnave in zagotavljanja varnosti pacientov z različnimi vrstami vsadkov. Pripravili smo tudi osnutek slovenskih priporočil o MR varnosti, ki temelji na analizi vprašalnika in tujih priporočil.Introduction: Nowadays, magnetic resonance imaging is one of the most important diagnostic methods. It is distinguished by its superior contrast of soft tissue and the lack of ionising radiation. Despite its usefulness, it can still be the source of many dangers for a patient. There are cases in which a person concerned cannot be subject of the examination procedure. Any implant which can be affected by magnetic or electric field, must not come close to the magnetic force field. We must never assume the object’s safety level if the latter is not determined or documented. There are a lot of potential dangers, for example: some of them originate from the static magnetic field, radiofrequent electromagnetic (RF) field and gradient magnetic field. Purpose: The purpose of our diploma work is to identify ways of suitability testing for implanted medical devices used by radiographers throughout MRI diagnostics in Slovenia. Methods: The theoretical part of our diploma work is based on the systematic examination of expert written articles published on the internet, foreign guidelines on MR safety and book sources on magnetic resonance diagnostic. For the needs of the empirical part of the diploma work, we made a questionnaire with the help of an online program called 1ka. The questions cover six different types of implants, field of treating an unknown implant, and the field of the department’s MR safety. The questionnaire was sent to teams working in the MR departments across Slovenia. The received data was then processed via program 1ka and Microsoft Excel Office. Results: 100% of radiographers who filled out the form stated that they have experience in examining patients with implanted orthopaedic implants and patients with implanted intravascular stents. 86% of radiographers had examined patients with implanted pacemakers in the past, 73% of radiographers had examined patients with intracranial aneurysm clips, 95% radiographers examined patients with implanted artificial heart valves, and 82% of radiographers had examined patients with implanted cochlear implants. 68% of them have experience with examining patients with implanted medical device of unknown origin (without official documentation). Follow-up questions were based on previous answers. Discussion and conclusion: Analysis has shown that the work of Slovenian radiographers throughout MRI diagnostics in Slovenia is comparable to the widely acknowledged foreign MRI Safety Guidelines. Their work corresponds to the guidelines in the field of implementation of measures reducing distortions caused by implants, in the field of assuring MRI safety of the patients with different implanted medical devices, in the field of dealing with implanted medical devices of unknown origin. We have also prepared a draft of Slovenian MRI Safety Guidelines based on analysis of the foreign guidelines and our questionnaire
Determining the need for an expanded fitness component in the Fire Science Program at Milwaukee Area Technical College
No full textIncludes bibliographical references
Extremální kombinatorika matic, posloupností a množin permutací
No full textTitle: Extremal combinatorics of matrices, sequences and sets of permutations Author: Josef Cibulka Department: Department of Applied Mathematics Supervisor: Doc. RNDr. Pavel Valtr, Dr., Department of Applied Mathematics Abstract: This thesis studies questions from the areas of the extremal theory of {0, 1}-matrices, sequences and sets of permutations, which found many ap- plications in combinatorial and computational geometry. The VC-dimension of a set P of n-element permutations is the largest integer k such that the set of restrictions of the permutations in P on some k-tuple of positions is the set of all k! permutation patterns. We show lower and upper bounds quasiexponential in n on the maximum size of a set of n-element permutations with VC-dimension bounded by a constant. This is used in a paper of Jan Kynčl to considerably improve the upper bound on the number of weak isomorphism classes of com- plete topological graphs on n vertices. For some, mostly permutation, matrices M, we give new bounds on the number of 1-entries an n × n M-avoiding matrix can have. For example, for every even k, we give a construction of a matrix with k2 n/2 1-entries that avoids one specific k-permutation matrix. We also give almost tight bounds on the maximum number of 1-entries in matrices avoiding a fixed layered...Název práce: Extremální kombinatorika matic, posloupností a množin permutací Autor: Josef Cibulka Katedra: Katedra aplikované matematiky Vedoucí disertační práce: Doc. RNDr. Pavel Valtr, Dr., Katedra aplikované ma- tematiky Abstrakt: V této práci se zabýváme oblastmi extremální teorie {0, 1}-matic, posloupností a množin permutací, které mají četná využití v oblasti kombina- torické a výpočetní geometrie. VC-dimenze množiny n-prvkových permutací P je největší celé číslo k takové, že množina zúžení permutací z P na některou k-tici pozic je množina všech k-prvkových permutací. Projdeme všemi třemi zmíněnými oblastmi extremální kombinatoriky, abychom dokázali horní a dolní meze, rostoucí kvaziexponenciálně v n, na maximální možnou velikost množiny n- permutací s VC-dimenzí shora omezenou konstantou. Tento výsledek využívá ve svém článku Jan Kynčl k výraznému snížení horního odhadu na počet tříd slabého izomorfismu úplného topologického grafu na n vrcholech. Dále pro některé, ze- jména permutační, matice M dokážeme nové meze na počet jedniček v M-prosté {0, 1}-matici velikosti n × n. Například pro každé k zkonstruujeme matici s k2 n/2 jedničkami prostou jedné konkrétní permutační matice velikosti k ×...Katedra aplikované matematikyDepartment of Applied MathematicsFaculty of Mathematics and PhysicsMatematicko-fyzikální fakult
Improving wellbeing in universities: a transdisciplinary systems change approach
No full textIn order for universities to flourish, we need to ensure that their staff and students are well mentally, physically and socially. Improving wellbeing is an open, systemic and complex challenge, because it contains many interrelated and dynamic problems and concerns. Such challenges cannot be ‘solved’ by using traditional and reductionist problem-solving strategies. In this paper we demonstrate how we worked towards an integrated systemic design and transdisciplinary innovation approach to improve the wellbeing of staff and students at the University of Technology Sydney. We developed a systemic vision of university wellbeing which considers wellbeing a characteristic of the community as a whole, and an integral part of education and research, rather than an issue that needs to be addressed by a separate ‘service’. The transdisciplinary and systemic design approach is further characterised by an ongoing evolutionary action-approach; an integration of diverse ways of knowing including various academic disciplines, Indigenous ways of knowing and community knowledge; and a structured learning strategy to support system change based on mutual learning and reflexivity. We discuss how this case illustrates how transdisciplinary learning approaches can strengthen systemic design practicesMethodologie en Organisatie van Desig
Wideband channel measurements at 60 GHz in different environments
No full textFor future mobile multimedia communication, a Mobile Broadband System is in development, which operates at a frequency of 60 GHz. In order to get a better understanding of 60 GHz propagation effects in different environments with different conditions, several measurements were performed, using a spectrum analyzer and synthesized signal generator for the frequency-domain characterization of the radio channel. In the experiments, a carrier wave (CW) was swept with constant amplitude across the 100 MHz band, centered on 59.9 GHz. The channel frequency response was measured at the receiver side. The results can be used for the design of an OFDM (Orthogonal Frequency Division Multiplex) system. The measurement environments were a corridor and a big college room in a high-rise office building (indoor) and a parking and a grassfield at the side of that building (outdoor). The spectrum samples were taken in each of the environments. From such samples, parameters that describe the wireless channel can be calculated like the Rice parameter k, the path loss coefficients, coherence bandwidth and the delay spread. It was necessary to develop an appropriate measurement analysis, stemming from the fact that the spectrum analyzer gives no information on the phase, only amplitude. Measurement analysis method and results are explained. When more and more dense measurements are performed a more detailed and accurate description of the wireless channel for the different environments is possible.Electrical Engineering, Mathematics and Computer ScienceTelecommunicatie- en Verkeersbegeleidingssysteme
A deterministic Indoor Propagation Prediction Technique using Ray tracing and Field Measurements at 60 GHz
No full textIn this thesis we present a ray tracing (deterministic) method for predicting the received power and the delay spread for indoor scenarios. This method is then applied to a specific environment, where frequency domain measurements have already been conducted. Results for both measured and predicted data are presented in parallel and compared. Additionally, with ray tracing we calculate some parameters that was not possible to measure. The way that several factors (material characteristics, antenna patterns, etc) affect the propagation has also been examined by changing the initial values of the problem.Electrical Engineering, Mathematics and Computer Scienc
Management in the Function of Enlargement of the Issuing Profit
No full textThe author starts from the thesis that it is especially necessary to manage the production of cash money, taking into consideration and applying the conceptions of modern management. Cash money (metallic and paper) is a specific “product” that is produced according to the needs of monetary traffic, as well as meeting the standards related to modern notaphily, i.e. numismatics. For several reasons, the author elaborates his thesis on the example of the issuing of Croatian contemporary metallic money. The most important of these reasons are that Croatia has its own mint, that issuing metallic money makes it possible to attain significant non-fiscal effects through its management, and that the issuing of national money has wider cultural, social, legal and other dimensions. In the elaboration of his thesis, the author takes into account the influence of the globalization and integration processes in which Croatia is a participant.management, innovation, issuing profit, money, exchange rate, Euroland
Polyporales - försök till en ny klassificering
No full textA new classification of Polyporales. The author gives a brief account of her on-going studies in Polyporales aiming at a new syste- matic classification based of molecular data
William Morris in kritična utopija visoke fantazije
No full textThe novels The Wood Beyond the World (1894) and The Weil at the World\u27s End (1896) by William Morris are considered the formative works of the type of literature which has been labelled high fantasy. The latter is one of the commercially most successful genres of fantasy literature. The two novels are analysed from the perspective of critical utopianism as articulated through a distinctive type of aesthetic structure which was established in these works and has become characteristic of the high fantasy literature. The author of the article suggests that it is this complex of aesthetic structiire-aiid ifs iiiherent iitopian lmpulse which may be one of the important faciors-in the perennia popularity of high fantasy.Romana Williama Morrisa The Wood Beyond the World (1894) in The Weil at the World\u27s End (1896) veljata za prva primera tipa literature imenovanega "visoka fantazija". Gre za eno izmed komercialno najbolj uspešnih zvrsti fantazijske literature. Deli sta analizirani iz perspektive kritičnega utopizma, kot se artikulira skozi posebno estetsko zgradbo, ki jo vzpostavita romana in je postala značilna za zvrst visoke fantazije. Pisec članka predlaga, da je morda prav ta kompleks estetske strukture in pripadajočega utopičnega impulza eden izmed pomembnih dejavnikov pri trajni popularnosti visoke fantazije
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