This thesis is devoted to the development of nano-focusing refractive optics for high energy X-rays using planar microelectronic technology. The availability of such optics is the key for the exploitation of high brilliance third and fourth generation X-ray sources. Advancements in the quality of optics available are commensurate with advancements in the fabrication technology. The fabrication process directly influences the quality and performance, so must be understood and controlled. In the first part of this thesis, the development of high aspect ratio Si kinoform lenses is examined. It is shown that control of the re-entrance angle is critical for successful fabrication; in fact, a large re-entrance angle can destroy the lens during the fabrication process. Through an etch study, it was found that as aspect ratio increases, control of the re-entrance angle becomes harder. To control the re-entrance angle for very high aspect ratios, a novel approach based on sacrificial structures was proposed and initial results presented. The second part is dedicated to an experimental study of refractive lenses made from diamond. Due to its low atomic number, relatively high density and very high thermal conductivity, diamond is one of the most desirable lens materials for refractive X-ray optics. However, due to its extreme hardness, it is very difficult to structure into a form suitable for X-ray lenses. To overcome this difficulty a Si moulding technique was used and focusing down to a 400 nm wide spot was achieved. Several obstacles were encountered and successfully overcome. The hardest obstacle was to obtain selective void-free filling in the Si moulds. Several methods were investigated. A method based on a sacrificial oxide layer and an Electrostatic Self-Assembly process was found to be the most useful. The approach discovered in this thesis is not limited to X-ray lenses, but can be applied to a wide variety of high aspect ratio MEMS requiring void-free diamond filling and smooth sidewalls.

Cellular growth, development, differentiation, and death are mediated to some degree by the interaction of soluble factors with plasma membrane receptors. Traditionally the cellular response to chemical cues has been studied by exposing entire culture dishes to a desired reagent. While the addition of soluble reagents homogenously to cell culture dishes provides a basis for understanding much of cell biology, greater spatial resolution of reagent delivery is necessary in order to elucidate mechanisms on the subcellular scale. This dissertation explores techniques that may improve the quality and precision of delivering soluble factors to cultured cells in order to better understand the complex processes of cell biology. These advancements were made possible by applying high intensity, focused laser light to soluble materials to achieve microscopic three-dimensional (µ-3D) printing. In combination with a previously developed microfluidic cell dosing platform, microstructures were designed and µ-3D printed to hydrodynamically focus reagent streams for cell dosing. Structures were also µ-3D printed within micrometers of living cells from a solution of gelatin and bovine serum albumin with minimal cytotoxicity. When µ-3D printed, these proteins displayed both temperature and pH-responsive properties. In order to allow for on-the-fly control of reagent stream size and temporal pulse width, microstructures were µ-3D printed from temperature-responsive N- isoproplyacrylamide. To further improve the temporal resolution of the system, a technique for cycling between reagents with millisecond exchange times using laminar flow microfluidics was developed. The utility of these techniques was demonstrated by staining rat Schwann cells and mouse neuroblastoma rat glioma hybrid cells (NG108-15) with focused streams of fluorescent dyes. These advancements may allow future experiments to determine the placement of soluble factors necessary for bacterial quorum sensing or stem cell differentiation. / text

<p>Mass spectrometry is widely considered to be the gold standard of elemental analysis techniques due to its ability to resolve atomic and molecular and biological species. Expanding the application space of mass spectrometry often requires the need for portable or hand-held systems for use in field work or harsh environments. While only requiring “sufficient” mass resolution to meet the needs of their application space, these miniaturized systems suffer from poor signal to background ratio which limits their sensitivity as well as their usefulness in field applications. </p><p>Spatial aperture coding techniques have been used in optical spectroscopy to achieve large increases in signal intensity without compromising system resolution. In this work similar computational methods are used in the application of these techniques to the field of magnetic sector mass spectrometry. Gains in signal intensity of 10x and 4x were achieved for 1D and 2D coding techniques (respectively) using a simple 90 degree magnetic sector test setup. Initial compatibility with a higher mass resolution double focusing Mattauch-Herzog mass spectrograph is demonstrated experimentally and with high fidelity particle tracing simulations. A novel electric sector lens system was designed to stigmate high order coded aperture patterned beam which shows simulated gains in signal intensity of 50x are achievable using these techniques.</p> / Dissertation

Analysis of low-abundance components in small samples remains a challenge within bioanalytical chemistry, and new techniques for sample pretreatments followed by sensitive and informative detection are required. In this thesis, procedures for preconcentration and separation of proteins and peptides in open microchannels fabricated on silicon microchips are presented. Analyte electromigration was induced by applying a voltage along the channel length, and detection was performed either by matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS) within the open channel, or by sampling a nL fraction containing the preconcentrated analytes from the channel for subsequent nano-electrospray ionization- (nESI-) or MALDI-MS. Utilizing solvent evaporation from the open system during sample supply, sample volumes exceeding the 25-75 nL channel volume could be analyzed. For preconcentration/separation of components in the discrete channel volume a lid of inert fluorocarbon liquid was used for evaporation control. In Papers I and II, aqueous, carrier-free solutions of proteins and peptides were analyzed, and the method was successfully applied for fast and simple preconcentration of amyloid beta (Aβ) peptides, related to Alzheimer’s disease. The impact of possible impurities in the analysis of carrier-free solutions was investigated in Paper III with the 1D simulation software GENTRANS, and a method for open-channel isoelectric focusing in a tailor-made pH gradient was developed. The latter approach was used in Paper IV for preconcentration and purification of Aβ peptides after immunoprecipitation from cerebrospinal fluid and blood plasma, followed by MALDI-MS from a micropillar chip. Paper V includes simulations of an isotachophoretic strategy for selective enrichment of Aβ peptides. GENTRANS simulations were used to select the electrolyte composition, and 2D simulations in a geometry suitable for on-chip implementation were performed using COMSOL Multiphysics. / <p>QC 20160930</p>

At the MAX-IV lab in Lund, there is a current goal to build a new soft X-Ray laser. The beam will be generated from a free-electron laser (FEL), which is an instrument consisting of high-speed electrons. The electrons move through alternating magnetic fields, causing the beam to become monochromatic. After the FEL, the Xrays will enter a beamline consisting of different optical components, such as mirrors, gratings and slits. This project investigated the necessary parameter values of the components, in order for the new X-Ray laser to focus the beam enough. The project consisted of a theoretical part and a simulation part. The use of so-called Kirkpatrick-Baez mirrors enables the beam to be very focused. The best focus achieved was 7.23um*10.87um for ''Pink beamline'' and the intensity at the end was 71.5%, which meant that only 30% of the rays were lost. For the monochromatic beamline, a loss of intensity is inevitable. With a pair of KBmirrors, this beam was focused to be 6.95um*9.80um. The energy spread is ranging from 6.198 eV to 0.3442 eV. The analytical calculations for the spot size matched well with the simulations. The pink beamline which was built in Ray satisfied the criterias of a spot size and intensity loss. The monochromatic beamline did fullfil the criterias of spot size and narrowing the energy spread. A loss of intensity will for this beamline be inevitable. Studying the misalignment effect showed that the components were most sensitive for vertical misalignment. The most sensitive parameters were the curvature of the mirrors.

Les techniques de contrôle non-destructif s’appuyant sur des traducteurs ultrasons multi-éléments sont maintenant de plus en plus utilisées dans l’industrie. Ces traducteurs offrent en effet de nombreux avantages, en particulier une polyvalence d’utilisation et une adaptabilité à des configurations complexes. De plus des techniques d’acquisition avancées, telle que la Full Matrix Capture, permettent d’avoir accès à des données beaucoup plus riches et complètes que celles fournies par les techniques conventionnelles, offrant ainsi de nouvelles possibilités en terme de localisation et de caractérisation de défauts. Les travaux de cette thèse ont pour objectif de mettre en œuvre des méthodes d’imagerie et de reconstruction adaptées aux diverses acquisitions multi-éléments possibles. Pour cela, nous proposons différentes méthodes dérivées de l’approche dite de focalisation synthétique. Ces méthodes s’appuient sur des modèles directs développés au CEA LIST et implémentés dans la plateforme CIVA. Ces derniers peuvent, en outre, prendre en compte les configurations de contrôle complexes, notamment en ce qui concerne l’état de surface -irrégulier- des pièces inspectées. Dans un premier temps, nous nous sommes intéressés à la localisation de diffracteur quasi-ponctuel. Sous cette hypothèse, nous avons évalués les performances des méthodes proposées lorsqu’elles sont appliquées à différents types d’acquisitions. La suite des travaux s’est recentrée sur l’étude de la Full Matrix Capture couplée à l’algorithme dit de « Focalisation en Tous Points (FTP) », cette combinaison ayant montré de bonnes performances en terme de localisation. Dans un second temps, nous avons prolongé notre approche à la reconstruction de défauts étendus et à la prise en compte de trajets ultrasonores multiples. En particulier, nous avons appliqué la généralisation de l’algorithme FTP à la localisation et à la caractérisation d’entaille proche du fond de la pièce à l’aide d’échos de coin, échos dus à des réflexions successives de l’onde ultrasonore sur le fond et le défaut. Les différentes méthodes envisagées dans ces travaux ont été appliquées avec des données simulées ainsi qu’avec des mesures expérimentales. / Techniques for nondestructive testing based on ultrasonic phased array probe are now increasingly used in industry. These probes offer many advantages, in particular use versatility and adaptability to complex configurations. More advanced acquisition techniques, such as “Full Matrix Capture”, provide access to collection of data richer and more complete than those provided by conventional techniques, offering so new possibilities in terms of localization and characterization of defects. The work of this thesis aims to implement imaging and reconstruction methods for various operating modes of UT array inspection. For this, we propose different methods derived from the so-called synthetic focusing. These methods rely on forward models developed at CEA LIST and implemented in the CIVA software platform. These models can also take into account the complex inspection configurations, especially in regard to the -irregular- surface inspected parts. At first, we were interested in locating point-like scatterer. Under this hypothesis, we evaluated the performance of the proposed methods when they are applied with different types of inspection operating mode. Next work has been refocused on the study of the Full Matrix Capture coupled to the algorithm called Focalisation en Tous Points (FTP), this combination has shown good performance in terms of defect localization. In a second step, we generalized our approach to extended defects and multiple ultrasonic paths. In particular, we applied the latest FTP algorithm to the localization and characterization of notch near the bottom of the part with corner echoes, echoes due to successive ultrasonic wave reflections on the bottom and defect. The different methods considered in this work have been applied with both simulated data and experimental measurements.

O direito à educação de pessoas com deficiência tem provocado e instigado inúmeras discussões, de caráter político e acadêmico, de forma intensa desde os anos 90. Tais discussões transitam pela defesa do acesso à educação, pela busca de novas formas de se compreender e analisar as situações de deficiências, pela constituição de políticas sociais não assistencialistas, pela discussão da relação público e privado na promoção de serviços de atenção às especificidades das deficiências, e, ainda, pelo financiamento necessário para uma atenção de qualidade. Esses campos se desdobram em seus interiores em tantos outros, mas todos terão como diretriz de suas proposições a garantia de um tratamento igualitário, sob as premissas dos direitos humanos. A proposição da pesquisa, desenvolvida nessa dissertação, centrou-se especificamente no campo da educação e na análise da Política Nacional de Educação Especial na Perspectiva Inclusiva (PNEE), considerando-se que tal documento buscou interpretar e direcionar as transformações necessárias no direito à educação das pessoas com deficiência, como uma resposta, ao conjunto de discussões. O papel da educação especial e a correlação com a educação inclusiva também serão abordados buscando compreender as relações e as consequências destas aproximações na política educacional. Dessa forma, a partir do fundamento, talvez principal na escrita desse documento, de que a reconfiguração dessa área primava pela atenção aos direitos humanos, definiu-se como objetivo primeiro e basal, inclusive como procedimento metodológico, retomar o estabelecimento da educação como um direito humano, no conjunto dos direitos sociais, e a implicação dessa diretriz na formulação das políticas públicas. Apresentou-se, complementar à análise, a necessária discussão sobre o universal e o focalizado na elaboração das políticas públicas, além da necessidade de se diferenciar, no interior das ações específicas direcionadas a grupos também específicos, as ações direcionadas de atenção e aquelas formuladas sob a égide da focalização no interior de uma política de Estado mínimo. Outro objetivo estabelecido, temática também muito cara no interior do objeto de estudo proposto para análise, foi compreender como perpassa ao debate a discussão sobre a experiência humana da deficiência, proposta por diferentes modelos e abordagens, e que tem consequências diretas na formulação das políticas sociais, seja na forma de atenção direcionada ou focalizada. Tomou-se como pressuposto para a análise as discussões do modelo social de compreensão da deficiência, pois esse é o modelo de maior aderência, até o presente momento, nos debates das políticas públicas de atenção à pessoa com deficiência no cenário nacional. Por fim, retomo o documento da PNEE buscando realizar análise do conteúdo, aí presente, das interpretações do direito à educação, a partir das perspectivas construídas nas discussões propostas anteriormente nessa dissertação. Não se colocou como objetivo nesse ponto analisar os contextos de influência que resultaram na elaboração, no entanto, ainda que se apresente como expressão discursiva de uma hegemonia do pensamento nacional, as brechas e contradições se apresentam. / The right to education of persons with disabilities has provoked and instigated numerous discussions of political and academic character, intensely since the 1990s. Such discussions transit through the defense of access to education, seeking new ways to understand and analyse situations of disability, by the constitution of nonassistentialist social policies, the discussion of public and private relations in the promotion of attention services to the specificities of disabilities, and also by the financing needed for quality attention. These fields unfold in their interiors and in so many others, but all of them will have as guideline of their propositions the guarantee of an equal treatment, under the premises of human rights. The research proposition, developed in this dissertation, focused specifically on the field of education and analysis of the National Policy on Special Education in the Inclusive Perspective (PNEE), considering that such document sought to interpret and direct the necessary transformations in the right to education of persons with disabilities, as an answer to the set of discussions. The role of special education and the correlation with inclusive education will also be addressed aiming to understand the relationships and consequences of these approaches in educational policy. Thus, from the foundation, perhaps main in the writing of this document, that the reconfiguration of this area highlighted by the attention to human rights, it was defined as a first and basal objective, including as a methodological procedure, to retake the establishment of education as a human right, in the social rights as a whole, and the implication of this guideline in the formulation of public policies. The necessary discussion about the universal and the focused on the elaboration of public policies was presented, complementary to the analysis. It was also considered necessary to differentiate the specific actions also directed to specific groups, the targeted actions of attention and those formulated under the support of focusing inside a minimal state policy. Another established objective, which is also thematically important within the study object proposed for analysis, is to understand the discussion about the human experience of disability, proposed by different models and approaches and which have direct consequences on the formulation of social policies, either in the targeted or focused attention way. The discussion of the social model of understanding disability was taken as the presupposition for this analysis, since this is the greater adherence model, up to the present moment, in the debates of the public policies of attention to the persons with disability, in the national scenario. Finally, I return to the PNEE (National Policy on Special Education in the Inclusive Perspective) document aiming to content analysis of the present discourse of the interpretations of the right to education, from the built up perspectives earlier proposed in this dissertation. It was not aimed at this point to analyse the contexts of influence that resulted in the elaboration, however, even if it presents itself as a discursive expression of a hegemony of national thought, the breaches and contradictions are present.

Under de år som gått sedan 1970-talets krisår har textilbranschens utseende förändrats. För att hitta nya nischer att utmärka sig i, har företagen velat se ett mer affärsmässigt tänkande i sin organisation, något som snappades upp av Textilhögskolan. På skolan såg man att det fanns ett kunskapshål som varken ekonomer, ingenjörer eller designers fyllde upp. Resultatet blev den tvååriga utbildningen Affärs- och produktutveckling med inriktning mot textila produkter, som sedan döptes om till Textil produktutveckling med entreprenörs- och affärsinriktning . Sedan starten 2006 har ett påbyggnadsår lagts till, och ett namnbyte skett, för att förtydliga utbildningens innehåll. Under en föreläsning uppkom dock frågan om huruvida studenterna känner att de egentligen lär sig det som utbildningen strävar efter att lära ut, och om de verkligen blir förberedda för arbetslivet. En förvirrad gästföreläsare frågade ett helt klassrum fullt med studenter från TPU vad de egentligen blir när det är färdigutbildade, och ingen kunde svara.Denna förvirring har gett upphov till den här rapporten som har som syfte att ge förslag för att förbättra och förtydliga utbildningen så att alla parter förstår vad den innehåller, samt ge en tydlig bild av vad som är tanken med de examinerade studenternas framtid. För att göra en fullständig belysning av programmet valde vi att titta på det ur tre synvinklar; studenternas, utbildningsledningens och branschens, samt även undersöka hur TPU står sig i konkurrens med andra utbildningar på Textilhögskolan. Denna information fick vi fram genom att göra intervjuer med studenter, ansvariga på skolan samt företag i branschen som arbetar med produktutveckling. Vi gjorde även en jämförelse mellan programinnehållet i TPU och två andra utbildningar på Textilhögskolan.Resultatet blev ett förändringsförslag som delades upp i kategorierna undervisning och marknadsföring. Vi fann att utbildningen inte gav ett tillräckligt underlag för att arbeta med det som teorin och empirin visade att en produktutvecklare gör, och det var tydligt att studenterna inte heller kände sig som produktutvecklare. Detta ledde i sin tur till ett förslag på namnbyte, vilka kurser som bör ändras för att passa in under det nya namnet samt ett förslag på hur skolan kan marknadsföra programmet. Vidare kom vi även till slutsatsen att om skolan vill behålla det nuvarande namnet får man göra en total omstrukturering av innehållet, men att man då riskerar att förlora det som var grundtanken med utbildningen. / <p>During the years since the textile crisis of the 1970’s, much has altered within the textile industry. In order to find new markets in which to succeed, a more businesslike approach has been sought after by the industry. This was picked up by the Swedish School of Textiles in Borås, who saw that there was a gap of knowledge that neither the economists nor engineering nor design students filled. The schools solution to this gap was the educational program Business and Product Development focusing on Textile products, later known as Textile Product Development focusing on Entrepreneurship and Business, TPU. Since the start in 2006, an additional year has been added, and the change in name was made in order to further emphasize the fundamental nature of the program. However, during a lecture the question arose to whether or not the students felt that they were actually learning the things that the education is striving to teach. A confused guest professor asked a room full of students from TPU what they were supposed to be working with after their education was finished. Equally confused, none of the students could answer this question.This confusion was the starting point of this essay, which has the purpose to improve and clarify the education in a way so it becomes clear to all involved parties what the aims and goals of the education are. Furthermore, the report also aims to give a clear picture of the intended roll of the students of TPU in the working life. In order to do this, we chose to look at the educational program from three different perspectives; the students’, the industry’s and the school management’s, and also investigate how competitive TPU are compared to other educational programs. To get these different perspectives, we interviewed the students, the school management and companies within the textile industry, who are working with product development. We also did a comparison between TPU and two other educational programs given at the Swedish School of Textiles. The result of the evaluation was that a change was needed. Thus, a proposition containing suggestions of change and improvement, divided in to the categories education and marketing was created. We found that the program TPU did not build the foundation that is needed in order to work with the things that the theory and empirics said that a product developer do. It also became clear that the students of TPU did not feel like product developers, nor were they becoming one. Consequently, we propose a change in title of the educational program, courses which should be included in order to fit the new title, and also a suggestion to how the school management can market the program. Furthermore, we also reached the conclusion that if the school decides to keep the original title, a complete restructuring of the study courses needs to be done, but doing this imposes a risk of losing the original aim and idea of the program.</p><p>Program: Kandidat inom Magisterutbildning i fashion management med inriktning modemarknadsföring</p>

Titel: Inköpsassistent – vem får jobbet? En studie i konkurrensen mellan textila utbildningar iBorås.Författare: Sandra Carlqvist och Sanna UlanderHandledare: Sven-Erik Hänel, TextilhögskolanTyp av arbete: C-uppsats i Textil produktutveckling med entreprenörs- och affärsinriktning 15 högskolepoängInstitution: TextilhögskolanSpråk: SvenskaHuvudämne: Hur står sig en student från programmet Textil produktutveckling med entreprenörs- och affärsinriktning (TPU) gentemot konkurrerande programstudenter från Textilekonom och KY-Teko när de söker jobb som inköpsassistent?Bakgrund: TPU är ett nytt program och i juni 2010 går den första avgångsklassen ut med kandidatexamen. Ingen fastställd statistisk finns över eventuella karriärvägar. Behovet att veta vad arbetsgivarna efterfrågar och hur konkurrensbilden ser ut är därför aldrig kartlagd.Syfte: Genom intervjuer med studenter och företag kartlägga hur en student från TPU bäst formulerar sig för att få ett jobb som inköpsassistent.Metod: Rapporten bygger på en empirisk undersökning. Metoden till denna undersökning är intervjuer, personliga och via e-post.Huvudresultat: En TPU-student står sig bra i konkurrens mot de undersökta programmen. / <p>Textile Product Development focusing on Entrepreneurship and Business is a new education at the Swedish School of Textiles in Borås. The program was founded in year 2005 and has not yet had a full class recieve a bachelor degree. Statistics does not exist over how former students are coping with work in the field of fashion and textiles. After some research we discovered that many students start out their education with a dream of becoming a buyer. Since there are two other educations from Borås, Textile Economics and KY-Teko, we see that the competition could be stiff in that field. These educations are traditionally what employees at buyer offices have studied.How does a graduate from the newly founded Textile Product Development focusing on Entrepreneurship and Business stand compared to the traditionally bound Textile Economics and KY-Teko when applying for a job as a buyers assistant?Out study shows that a graduate from Textile Product Development focusing on Entrepreneurship and Business stands well against competition from the other textile educations mentioned above.</p><p>Program: Kandidat inom Magisterutbildning i fashion management med inriktning modemarknadsföring</p>

Le faisceau d’électrons (500 keV, 30 kA, 100 ns) produit par le générateur RKA (Relativistic Klystron Amplifier) est utilisé pour étudier des matériaux soumis à des chocs de basse fluence (< 10 cal/cm²). Leur réponse dépend des caractéristiques du faisceau, principalement en termes d’homogénéité spatiale lors de l’impact. Dans ce but, nous avons utilisé des diagnostics électriques et un diagnostic optique basé sur l’émission Cerenkov. Les photons visibles produits sont détectables par des caméras rapides. Nous avons ainsi pu étudier l’homogénéité du faisceau émis dans la diode sous vide en fonction des matériaux utilisés pour la cathode et pour l’anode, mais aussi pu suivre sa propagation dans une enceinte contenant un gaz à basse pression.Chaque partie de l’installation a été optimisée lors de cette thèse. Nous avons constaté qu’une cathode en velours avec des fibres bien ordonnées était le meilleur émetteur. Une anode d’une dizaine de micromètres d’épaisseur permet de diffuser le faisceau avant qu’il n’impacte la cible, améliorant encore son homogénéité. Ces travaux sur la diode ont été complétés par une étude de la propagation du faisceau dans une enceinte remplie d’air ou d’argon à différentes pressions, avec ou sans focalisation produite par un champ magnétique externe. D’après les résultats expérimentaux, un faisceau d’électrons de 400 keV, 4,2 kA peut être propagé, avec un rayon constant, dans 0,7 mbar d’argon. Enfin, pour interpréter les expériences, des simulations ont été réalisées à l’aide du code Monte Carlo Geant4 pour calculer l’interaction du faisceau avec la cible Cerenkov et l’anode. Au niveau de l’émission et du transport du faisceau, le bon accord obtenu avec les prédictions du code PIC Magic permet d’estimer les distributions des électrons par la simulation et d’initialiser correctement les calculs de réponse des matériaux. / The electron beam (500 keV, 30 kA, 100 ns) of the RKA (Relativistic Klystron Amplifier) generator is used to study materials under shocks at low fluences (< 10 cal/cm²). Their response depends on the beam characteristics at the impact location, mainly in terms of spatial homogeneity. We have used electrical diagnostics as well as an optical diagnostics where the visible photons produced by Cerenkov emission in a silica target are collected by fast cameras. Beam homogeneity has been studied in the vacuum diode as a function of the materials used for the cathode and the anode. Beam propagation and focusing in a chamber filled with a low-pressure gas has also been investigated.Each part of the installation has been optimized during this work. We found that, among the tested materials, a velvet cathode with well-aligned fibers is the best emitter. An anode of thickness about ten micrometers improves the beam homogeneity by scattering of electrons. Next, we focused on beam propagation and focusing in the chamber. For example, a 400 keV, 4.2 kA electron beam can be propagated at constant radius in argon at 0.7 mbar. We performed simulations with the Monte Carlo code Geant4 in order to compute the beam interaction with the Cerenkov target as well as with the anode. Beam emission and propagation were simulated with the PIC code Magic. The good agreement with the experimental results allows us to estimate the electron distributions at any position along the beam path in order to initialize correctly the computation of the beam-material interaction.