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Investigation of optical properties of polymethines for potential application in all-optical signal processingKim, Hyeongeu 08 June 2015 (has links)
Demonstration of ultrafast all-optical signal processing (AOSP) using silicon as the active material has been limited by large two-photon absorption loss and long lifetimes of the resulting free carriers. For AOSP at speeds in the terahertz, an order of magnitude faster than that the fastest current electronic counterpart, a class of π-conjugated organic molecules called polymethines provides a promising alternative to silicon as they possess large third-order nonlinearities, and ultrafast polarization response to an incident field. The challenge in the application of polymethines as active nonlinear optical materials for AOSP is in translating their promising molecular properties into bulk material properties. The large linear polarizability and charged nature of the polymethines molecules strongly promote aggregation and phase-separation in solid blends, offsetting their advantageous molecular optical properties. In this work, polymethines’ resistance to deleterious spontaneous symmetry breaking and aggregation was enhanced by substitutions of metal- and chalcogen- containing terminal groups, and rigid steric groups above and below the π-conjugated plane of polymethine chain. The resulting polymethines/amorphous polycarbonate (APC) blend films demonstrated an unprecedentedly high two-photon figure-of-merit, |Re(χ(3))/Im(χ(3))| and low linear loss. The optical quality of the polymethines/APC films was also improved by replacing the commonly-used alkyl ammonium counterions with more polarizable aryl phosphonium counterions with moderate ground state dipole moment. The resulting dye-polymer blend films showed an enhanced near-infrared transparency while its magnitude of the third-order susceptibility, |χ(3)|, showed a good agreement with that extrapolated from the molecular third-order polarizability, γ. For facile integration of these promising organic materials into SOH, the substrate surface was functionalized using silane coupling chemistry for the reduction of surface energy mismatch between the polymer films and the waveguide containing substrates. The optical and SEM micrographs showed vastly improved coverage and infiltration of the microfeatures. Furthermore, to enable the precise engineering of waveguide cross-sectional dimensions for single-mode propagation in the organic cladding, the dispersion curves of the polymethines/polymer blends were generated using prism coupling and ellipsometry. The combined efforts in the development of molecules and materials discussed in the thesis have culminated into a successful identification and optimization of the polymethines dyes and their polymer blends for imminent demonstrations of on-chip AOSP at terahertz speed.
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Untersuchungen zu molekularen Mechanismen der Glucocorticoid-Resistenz bei Akuter Lymphatischer Leukämie (ALL) / Molecular mechanisms of glucocorticoid resistance in acute lymphoblastic leukemia (ALL)Hennig, Heike 01 July 2003 (has links)
No description available.
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All-inclusive hotellens påverkan i Alanya : En fält- och intervjustudie om hållbarheten i destinationenHultgren, Viktoria, Ibrahim, Layla, Hassan Alwan, Nagoua January 2013 (has links)
Denna studie behandlar Turkiets turistdestination Alanya utifrån ett hållbarhetsperspektiv. Vidare om all-inclusivehotellens påverkan på destinationen. Syftet med studien är att undersöka de sociala, ekonomiska och miljömässiga faktorerna. För att analysera detta använder vi oss av teorier som berör hållbar utveckling och hållbar turism samt positiva och negativa aspekter av all-inclusivekonceptet. Metoden för undersökningen är kvalitativ där en fält- och intervjustudie genomförs i Alanya. För att studera den sociala påverkan på destinationen undersöks turister och lokalbefolkningen samt arbetsvillkoren för anställda. Dessutom undersöks de internationella reseföretagen och all-inclusivehotellens ekonomiska och miljömässiga påverkan på destinationen. Resultat visar att Alanya inte bara är en charterdestination utan en all-inclusivedestination. Den snabba uppkomsten av all-inclusivehotell har lett till en ohållbar utveckling för destinationen. / This essay concerns the tourist destination Alanya in Turkey from a sustainable perspective and the impact all-inclusivehotels have on the destination. The purpose of the essay is to examine social, economic and environmental impacts in Alanya. To analyse it we use theories of sustainable development and sustainable tourism together with theories of all-inclusivehotels benefits and disadvantages. A field- and interview survey was conducted in Alanya to study the social effect on the destination. Tourist, locals and employees working condition are examined. Furthermore the essay analyses international travel agencies and all-inclusivehotels environmental and economic impacts. Conclusion of the essay presents that Alanya is not only a charter destination, it’s an all-inclusive destination. The rapid grow of all-inclusivehotels in Alanya have affected an unsustainable development in the destination.
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Triagem virtual de metabólitos secundários com potencial atividade antimicrobiana do gênero solanum e estudo fitoquimico de solanum Capsicoides allBarros, Renata Priscila Costa 13 February 2017 (has links)
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Previous issue date: 2017-02-13 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / The human body has a large bacterial flora, but when these bacteria, the principle of
commensal character, become part of site other than it's natural, they can cause some
severe diseases. Researches that are based either on the search of new drugs from plants
or on the improvement of phytotherapics are in prominence and continue to play an
important role nowadays. In this perspective, the aim was to carry out a phytochemical
study of Solanum capsicoides All. fruits to isolate and characterize the chemical
substances of this species and to use in silico studies to carry out investigations of new
molecules potentially active for methicillin resistant Staphylococcus aureus (MRSA) and
Escherichia coli using a database created with secondary metabolites isolated from
Solanum genus. The phytochemical study of Solanum capsicoides All. fruits resulted in
the isolation of three substances: carpesterol, acetylated glucose and 4-hydroxybenzaldehyde.
A review of the literature led to the creation of a database with 421
different secondary metabolites isolated from the Solanum genus. Two databases from
CHEMBL were selected. The first one with activity against MRSA and another against
E. coli. The compounds were classified according to the pIC50 values to generate and
validate the model using "Random Forest"(RF). The structure of six new target proteins
against S. aureus obtained from the PDB (Protein database) were used for virtual
screening of the based on the receptor structure using docking studies by the Molegro
Virtual Docker, reaching to select Solanum database molecules capable of interacting in
the binding sites of proteins. The RF prediction model for MRSA obtained a percent
accuracy of 81%, area under the Receiver Operating Characteristic (ROC) curve of 0.885,
selecting 8 molecules with an active potential above 60%. The prediction model for
Escherichia coli obtained an accuracy rate of 88%, area under ROC curve of 0.932,
selecting 4 molecules with potential probability above 84%. The study of the coupling of
six target enzymes to S. aureus selected an average of 50 molecules from the bank of 421
isolated molecules of the genus Solanum with an ability to interact with on active site of
each enzyme. In addition, it was possible to obtain 1 molecule with active potential and
interaction capacity with 5 enzymes studied, 7 molecules interacting with 3 enzymes and
6 with 2 enzymes of S. aureus. The rutin, a molecule potentially active in the in silico
study for S. aureus and E. coli, together with carpesterol, were tested in vitro against these
bacteria. Microbiological tests have shown that carpesterol has no antimicrobial activity
for the studied strains, and that the rutin has activity only for E. coli. An interaction study
with strains of S. aureus ATCC 25923, a standard strain sensitive to all antibiotics, and
SAM-01, a multidrug resistant strain, was designed. There was interaction only between
rutin and oxacillin, one of the three antibiotics studied in the interaction, for a strain SAM-
01, reducing the resistance of this strain. / O ser humano possui uma vasta flora bacteriana que é comensal, mas quando essas
bactérias, a princípio de caráter comensal, passam a fazer parte de outro sítio que não o
seu natural, podem causar graves patogenias. Pesquisas que se fundamentam na busca por
novos medicamentos a partir de plantas ou no melhoramento de fitoterápicos já existentes
vem se destacando e continuam a desempenhar um papel importante nos dias de hoje.
Nessa perspectiva objetivou-se realizar um estudo fitoquímico dos frutos de Solanum
capsicoides All. para isolar e caracterizar substâncias químicas desta espécie e, utilizando
estudos in silico, realizar investigações de novas moléculas potencialmente ativas para
Staphylococcus aureus resistente a meticilina (MRSA) e Escherichia coli, utilizando um
banco de dados criado com metabólitos secundários isolados do gênero Solanum. O
estudo fitoquímico dos frutos de Solanum capsicoides All. resultou no isolamento de três
substancias: carpesterol, glicose acetilada e 4-hidroxi-benzaldeído. A revisão de literatura
levou à criação de um banco de dados com 421 diferentes metabólitos secundários
isolados do gênero Solanum. Foram selecionados dois bancos de dados obtidos a partir
do CHEMBL. O primeiro com atividade contra S. aureus multirresistente (MRSA) e o
outro contra E. coli. Os compostos foram classificados de acordo com valores de pIC50
para gerar e validar o modelo utilizando “Random Forest”(RF). A estrutura de seis novas
proteínas alvo contra S. aureus obtidas do Protein Data Bank (PDB) foram utilizadas para
triagem virtual baseada na estrutura do receptor utilizando estudos de “docking” com o
software Molegro Virtual Docker, a fim de selecionar moléculas do banco de dados de
Solanum com potencial capacidade de interagir nos sítios de ligação dessas proteínas. O
modelo RF de predição para S. aureus multirresistente obteve uma porcentagem de acerto
de 81%, área sob a curva Receiver Operating Characteristic (ROC) de 0,885,
selecionando 8 moléculas com potencial ativo superior a 60%. O modelo de predição para
Escherichia coli obteve taxa de acerto de 88%, área sob curva ROC de 0,932,
selecionando 4 moléculas com probabilidade de potencial ativo superior a 84%. O estudo
do docking das seis enzimas alvo para S. aureus selecionou uma média de 50 moléculas
do banco de 421 moléculas isoladas do gênero Solanum com a capacidade de interagir no
sitio ativo de cada enzima. Analisando moléculas multitarget, foi possível obter 1
molécula com potencial ativo e capacidade de interação com 5 das 6 enzimas estudadas,
7 moléculas interagindo com 3 enzimas e 6 com 2 enzimas de S. aureus. A rutina, uma
molécula potencialmente ativa no estudo in silico para S. aureus e E. coli, juntamente
com o carpesterol, foram testadas in vitro contra essas bactérias. Os testes
microbiológicos mostraram que o carpesterol não possui atividade antimicrobiana para as
cepas estudadas, e que a rutina possui atividade apenas para a cepa de E. coli. Foi
realizado ainda estudo de interação com as cepas de S. aureus ATCC 25923, uma cepa
padrão sensível a todos os antibióticos, e SAM-01, uma cepa multirresistente. Houve
interação apenas entre a rutina e a oxacilina, um dos três antibióticos estudados na
interação, para a cepa SAM-01, diminuindo a resistência dessa cepa.
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Estado nutricional e efeito da vitamina A na resposta imune frente ? infec??o por Leishmania InfantumMaciel, Bruna Leal Lima 20 December 2013 (has links)
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Previous issue date: 2013-12-20 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / Nutritional status is an important determinant to the response against Leishmania infection, although few studies have characterized the molecular basis for the association found between malnutrition and the disease. Vitamin A supplementation has long been used in developing countries to prevent mortality by diarrheal and respiratory diseases, but there are no studies on the role of vitamin A in Leishmania infection, although we and others have found vitamin A deficiency in visceral Leishmaniasis (VL). Regulatory T cells are induced in vitro by vitamin A metabolites and are considered important cells implicated T CD4+ cell suppression in human VL. This work aimed to examine the correlation of nutritional status and the effect of vitamin A in the response against Leishmania infantum infection. A total of 179 children were studied: 31 had active VL, 33 VL history, 44 were DTH+ and 71 were DTH- and had negative antibody to Leishmania (DTH-/Ac-). Peripheral blood monuclear cells were isolated in a subgroup of 10 active VL and 16 DTH-/Ac- children and cultivated for 20h under 5 different conditions: 1) Medium, 2) Soluble promastigote L. infantum antigens (SLA), 3) All-trans retinoic acid (ATRA), 4) SLA + ATRA and 5) Concanavalin A. T CD4+CD25highFoxp3+, T CD4+CD25-Foxp3- and CD14+ monocytes were stained and studied by flow cytometry for IL-10, TGF-β and IL-17 production. Nutritional status was compromised in VL children, which presented lower BMI/Age and retinol concentrations when compared to healthy controls. We found a negative correlation between nutritional status (measured by BMI/Age and serum retinol) and anti-Leishmania antibodies and acute phase proteins. There was no correlation between nutritional status and parasite load. ATRA presented a dual effect in Treg cells and monocytes: In healthy children (DTH-/Ac-), it induced a regulatory response, increasing IL-10 and TGF-β production; in VL children it modulated the immune response, preventing increased IL-10 production after SLA stimulation. Furthermore, we found a positive correlation between BMI/Age and IL-17 production and negative correlation between serum retinol and IL-10 and TGF-β production in T CD4+CD25highFoxp3+ cells after SLA stimulus. Our results show a potential dual role of vitamin A in the immune system: improvement of regulatory profile during homeostasis and down modulation of IL-10 in Treg cells and monocytes during symptomatic VL. Therefore, the use of vitamin A concomitant to VL therapy might improve recovery from disease status in Leishmania infantum infection / O estado nutricional ? importante determinante da resposta ? infec??o por Leishmania. No entanto, s?o poucos os trabalhos que caracterizem as bases moleculares das associa??es encontradas entre a desnutri??o e a doen?a. A suplementa??o de vitamina A ? utilizada em pa?ses em desenvolvimento para reduzir a mortalidade por diarreia e doen?as respirat?rias. Apesar disso, n?o existem estudos sobre o papel da vitamina A na infec??o por Leishmania apesar de nosso grupo e outros terem demonstrando a defici?ncia de vitamina A durante a leishmaniose visceral (LV). As c?lulas T regulat?rias s?o consideradas c?lulas supressoras durante a LV e s?o induzidas por metab?litos de vitamina A. Este trabalho teve como objetivo verificar a correla??o do estado nutricional e o efeito da vitamina A na resposta frente ? infec??o por Leishmania infantum. Foram estudadas 179 crian?as, sendo 31 casos de LV ativa, 33 com hist?ria pregressa de LV, 44 DTH+ e 71 DTH- e Anticorpo anti-Leishmania negativo (DTH-/Ac-). C?lulas mononucleadas de sangue perif?rico foram isoladas em um subgrupo de 10 crian?as com LV e 16 DTH-/Ac-, sendo cultivadas por 20h sob as seguintes condi??es: 1) Meio, 2) Ant?genos sol?veis de promastigotas de L. infantum (SLA), 3) ?cido all-trans retin?ico (ATRA), 4) SLA + ATRA e 5) Concanavalina A. As c?lulas T CD4+CD25highFoxp3+, T CD4+CD25-Foxp3- e mon?citos CD14+ foram marcadas e estudadas por citometria de fluxo quanto ? produ??o de IL-10, TGF-β e IL-17. O estado nutricional apresentou-se comprometido nas crian?as com LV, que apresentaram menor IMC/idade e baixas concentra??es de retinol s?rico quando comparadas aos controles sadios. Observou-se correla??o negativa entre o estado nutricional (medido por ?ndice de Massa Corporal/Idade e retinol s?rico) e anticorpos anti-Leishmania e prote?nas de fase aguda. N?o foi encontrada correla??o entre o estado nutricional e a carga parasit?ria. O ATRA apresentou efeito distinto nas c?lulas Treg e mon?citos: Em crian?as saud?veis (DTH-/Ac-), induziu resposta regulat?ria, com aumento na produ??o de IL-10 e TGF-β; e, em crian?as com LV, modulou a resposta imune, diminuindo a produ??o de IL-10 ap?s o est?mulo com SLA. Foi encontrada correla??o positiva entre o IMC/Idade e a produ??o de IL-17 e correla??o negativa entre o retinol s?rico e a produ??o de IL-10 e TGF-β nas c?luas T CD4+CD25highFoxp3+ ap?s est?mulo com SLA. Os dados deste estudo permitem concluir que o estado nutricional comprometido durante a LV ? correlacionado com a resposta imune e inflamat?ria frente ? Leishmania. Al?m disso, possivelmente, a vitamina A apresenta duplo efeito na resposta imune: em crian?as sadias, promove resposta regulat?ria; durante a LV, reduz a produ??o de IL-10 em c?lulas Treg e mon?citos. Dessa forma, o uso de vitamina A durante a LV pode promover a recupera??o de pacientes em tratamento para a doen?a
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Concentração inibitória mínima e concentração bactericida mínima de extratos hidroalcoólicos das folhas de Myracrodruon urundeuva All. e Qualea grandiflora Mart. sobre Streptococcus mutans e Lactobacillus casei / Minimum inhibitory concentration and minimum bactericidal concentration of hydroalcoholic extracts of Myracrodruon urundeuva All. and Qualea grandiflora Mart. leaves on Streptococcus mutans and Lactobacillus caseiRita de Cassia Fabris 11 August 2017 (has links)
A cárie dentária é uma doença bucal de alta prevalência e impactante em países em desenvolvimento. É causada pela presença de biofilme dentário rico em bactérias acidogênicas e acidúricas, como Streptococcus mutans e Lactobacillus casei. Neste sentido, a fitoterapia tem sido aplicada na odontologia devido ao seu conhecido efeito antimicrobiano, tendo potencial para prevenir doenças como a cárie dentária. Portanto, o presente estudo tem como objetivo testar o potencial antimicrobiano de extratos bruto e etanólico das folhas de Myracrodruon urundeuva (M. urundeuva.) e Qualea grandiflora (Q. grandiflora) sobre S.mutans e L. casei. Para tal, determinaram-se a Concentração Inibitória Mínima (CIM) e a Concentração Bactericida Mínima (CBM). A CIM foi definida como a menor concentração do agente antimicrobiano capaz de inibir 100% o crescimento microbiano (absorbância) em relação aos controles negativos. Para a CBM, alíquotas foram removidas dos poços que não apresentaram nenhuma absorbância (viabilidade, concentrações CIM) e semeadas em placas de ágar BHI, incubadas por 24 h a 37°C em estufa de CO2 5%. A CBM foi determinada considerando a menor concentração dos extratos capaz de impedir o crescimento bacteriano visível. Cepas de S. mutans (ATCC 21175) e L. casei (ATTC 334) foram ativadas em BHI e caldo Rogosa, respectivamente. A CIM foi determinada pela técnica de diluição em microplacas de 96 poços (100 l de extrato + 80 l BHI/Rogosa + 20 l da bactéria diluída em BHI/Rogosa equivalente a 5x105 UFC/mL), as quais foram incubadas por 24 h (S. mutans) e 48 h (L. casei) a 37°C em estufa de CO2 5%. Os extratos de M. urundeuva e Q. grandiflora inicialmente foram diluídos em BHI/Rogosa variando as concentrações entre 2 mg/ml a 0,00012207 mg/ml e os mesmos extratos diluídos em álcool foram avaliados nas concentrações entre 20 mg/ml a 0,00244 mg/ml para S. mutans e L. casei. Não foi possível determinar a CIM e a CBM para os extratos diluídos no BHI/Rogosa. Foram utilizados como controle positivo a clorexidina e como controles negativos BHI/Rogosa com e sem álcool a 5%. As CIMs (CBMs) da M. urundeuva e Q. grandiflora, diluídas em álcool, e clorexidina contra S. mutans foram 2,5 mg/ml (2,5 mg/ml), 5,0 mg/ml (--) e 0,00468 mg/ml (0,00937 mg/ml), respectivamente. Em relação ao L. casei, as CIMs (CBMs) da M. urundeuva e Q. grandiflora, diluídas em álcool, e da clorexidina foram 0,156 mg/ml (0,312 mg/ml), 0,156 0,625 mg/ml (0,312 0,625mg/ml) e 0,00468 mg/ml (0,3 mg/ml), respectivamente. Como conclusão, nosso estudo mostrou que L. casei (ATTC 334) é mais susceptível aos extratos que S. mutans (ATCC 21175) e o extrato M. urundeuva apresenta melhor efeito antimicrobiano que a Q. grandiflora em S. mutans (ATCC 21175), porém os dois extratos apresentam efeito similar sobre L. casei (ATTC 334) e ambos foram inferiores à CHX. / Dental caries is an oral disease of high prevalence and impact in developing countries. It is caused by the presence of a dental biofilm rich in acidogenic and aciduric bacteria, such as Streptococcus mutans and Lactobacillus casei. Accordingly, phytotherapy has been applied in dentistry due to its known antimicrobial effect, having potential to prevent diseases such as dental caries. Therefore, the present study aims to test the antimicrobial potential of crude and ethanolic extracts of Myracrodruon urundeuva (M. urundeuva) and Qualea grandiflora (Q. grandiflora) leaves on S. mutans and L. casei. For this, the Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) were determined. MIC was defined as the lowest concentration of the antimicrobial agent capable of inhibiting 100% the microbial growth in comparison to the negative controls. For MBC, aliquots were removed from the wells that did not show any absorbance (viability, concentrations than MIC) and seeded on BHI agar plates, incubated for 24 h at 37°C and 5% CO2. The MBC was determined considering the lowest concentration of extracts capable of preventing visible bacterial growth. Strains of S. mutans (ATCC 21175) and L. casei (ATTC 334) were activated in BHI and Rogosa broth. MIC was determined by the dilution technique in 96-wells microplates (100 l of extract + 80 l BHI/ Rogosa + 20 l of bacterium diluted in BHI/Rogosa equivalent to 5x105 CFU/ml), which were incubated for 24 h (S. mutans) and 48 h (L. casei) at 37°C and 5% CO2. The extracts were firstly diluted in BHI/Rogosa varying the concentrations between 2 mg/mL and 0.00012207 mg/ml; the same extracts were also diluted in alcohol at concentrations ranging from 20 mg/ml to 0.00244 mg/ml and both tested against S. mutans and L. casei. It was not possible to determine the MIC and MBC for the extracts diluted in BHI/Rogosa. Chlorhexidine was used as positive control, while BHI/Rogosa with or without 5% alcohol were used as negative controls. The MICs (MBCs) of M. urundeuva and Q. grandiflora diluted in alcohol, and clorexidine against S. mutans were 2.5 mg/ml (2.5 mg/ml), 5.0 mg/ml (--) and 0.00468 mg/ml (0.00937 mg/ml), respectively. In respect to L. casei, the MICs (MBCs) of M. urundeuva and Q. grandiflora, diluted in alcohol, and chlorhexidine were 0.156 mg/ml (0.312 mg/ml), 0.156 0.625 mg/ml (0.312 0.625 mg/ml) and 0.00468 mg/ml (0.3 mg/ml), respectively. In conclusion, our study showed that L. casei (ATTC 334) is more susceptible than S. mutans (ATCC 21175) to the extracts and the extract of M. urundeuva has a better antimicrobial effect than Q. grandiflora against S. mutans (ATCC 21175), but both extracts have similar effect on L. casei (ATTC 334) and they were inferior to CHX.
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Návrh a realizace aktivních reproduktorových soustav s digitálním vstupem / Design and Implementation of Active Loudspeaker System with Digital InputUchytil, Filip January 2012 (has links)
The work is focused on a design of an active loudspeaker system with a bi-amp amplifier and a digital input. There is described the theory of a loudspeaker enclosure design and its practical implementation. Furthermore the work deals with a design and construction of input circuits such as a preamplifier, Baxandall tone control, active crossover, all-pass filter and S/PDIF. On the basis of the amplifier´s theory the optimal construction of amplifiers and their design are selected. The complex design of the loudspeaker box is devised so that it would reach a maximum acoustic power during the preservation of a low distortion.
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Bavorská CSU a rakouská ÖVP : postmateriální společnost, kartelizované politické strany? / Bavarian CSU and Austrian ÖVP: Postmaterialist Society, Cartel Parties?Bobek, Pavel January 2012 (has links)
Both the Bavarian and Austrian societies have been undergoing a broad process of change since 1945: they have experienced a long period of economical growth, a rise of standards in terms of social welfare and education, and thus a value change and a switch to at least partly postmaterial society. Accompanying this change, however, there has also been more public disapproval towards the official policies, the number of people going to the polls has sunk and so has the number of people who are likely to become involved in party politics. Particularly the big, dominant catch-all parties, such as CSU (Christian Social Union of Bavaria) and ÖVP (Austrian People's Party), have been losing their voters and members. As the thesis shows, the developments in both societies are quite similar, as the political culture of Bavaria and Austria - in spite of certain differences - shares many common characteristics. Also, both CSU and ÖVP did partly manage to adapt to the new circumstances, particularly in terms of party funding. Anyway, they did not fully follow the pattern of cartelisation to pursue this adaptation. This reveals the link between postmaterialist change and the development to cartel party to be only partly valid; however, both theories have proved to be helpful in understanding processes taking...
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A Simulation Study of Variability in Gate-all-Around Nanosheet Transistors / En Simuleringsstudie av Variabilitet i Gate-All-Around NanobladstransistorerTirumaladass, Virinchi January 2022 (has links)
Gate-all-around (GAA) nanosheet field effect transistors (NSFETs) seem to be one of the most promising replacement options for FinFETs towards scaling down below to the sub-7nm technology nodes. They offer better electrostatics and control of short channel effects (SCEs) due to their superior control over the channel and their large effective channel width. Moreover, one can vertically stack multiple nanosheets to improve the drive strength of the device at a much-relaxed geometry than an aggressively scaled FinFET. However, stacking nanosheets would result in complex device structure, leading to significant process variability. Process variations could arise from irregular sheet thicknesses, random doping fluctuations, strain-induced variability, temperature effects, etc. which would affect the performance of the device. This has put a great emphasis on the need to come up with a properly calibrated process and simulation tools to analyze the performance of the NSFETs by identifying the sources of process variations with utmost precision. For this purpose, a TCAD-based simulation assessment has been done to model the design and performance of GAA NSFETs. The study explores the impacts of the variation in various physical parameters including the number of nanosheets, the sheet thickness, the work-function (WF) of metal gate stack layers, operational temperatures and channel doping on the electrical performance of the NSFETs. Moreover, a detailed fabrication process simulation flow for the design of a 3-sheet GAA NSFET has been presented. The simulation results predict that the process variations primarily have an impact on the device threshold voltage (Vth) which in turn influences the on-off currents, and the sub-threshold swing of the device. A comparative analysis has been done to understand the deviation of these electrical characteristics from their ideal values as a result of these variations. / Gate-all-around (GAA) nanoblads-fälteffekttransistorer (NSFETs) verkar vara ett av de mest lovande ersättningsalternativen för FinFET transistorer för att möjliggöra skalning ner till sub 7nm teknologinoderna. Denna typ av transistorer har bättre elektrostatik och kontroll av kortkanalseffekter (SCE) tack vare sin goda kontroll över kanalen och sin stora effektiva kanalvidd. Man kan dessutom stapla nanoblad vertikalt för att förbättra komponentens strömdrivningsförmåga med en mer relaxerad geometri än för en aggressivt skalad FinFET. Att stapla nanoblad gör komponentens struktur mer komplex vilket leder till betydande processvariabilitet. Processvariationer kan uppstå från oregelbundna tjocklekar för bladen, slumpmässiga dopningsfluktuationer, töjningsinducerad variabilitet, temperatureffekter m.m. Alla dessa variationer kan påverka komponentens prestanda. Det är därför viktigt att etablera korrekt kalibrerade process- och simuleringsverktyg för att analysera prestandan hos nanoblads-transistorerna. För detta ändamål har en TCAD-baserad simuleringsstudie gjorts för att modellera designen och prestandan för GAA nanoblads-transistorer. Studien undersöker effekterna av variationen i olika fysiska parametrar, inklusive antalet nanoblad och bladtjockleken, utträdesarbetet för metallgaten, temperaturen och kanaldopningen på den elektriska prestandan hos nanobladstransistorerna. Dessutom har ett detaljerat processimuleringsflöde för utformningen av 3-blads transistorer presenterats. Simuleringsresultaten visar att processvariationerna i första hand har en inverkan på transistorns tröskelspänning som i sin tur påverkar av- och på- strömmarna och subtröskelegenskaperna. En jämförande analys har gjorts för att förstå avvikelsen mellan dessa elektriska egenskaper från deras idealvärden som ett resultat av dessa variationer.
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Kerrovská mikroskopie magnetických mikrostruktur / Kerr microscopy of magnetic microstructuresHovořáková, Kristýna January 2022 (has links)
The main objective of the thesis was to construct a wide-field Kerr microscope to study all-optical helicity-dependent (AOHDS) switching in FePt nanograins. The wide- field Kerr microscope was successfully implemented into AOHDS experiments, was fully characterized and optimized for maximum image contrast. The real-time imaging and resolution of 2, 5µm enables the study of a wide range of magnetic materials and their dynamics. Moreover, a new light source, the High Lumen Density MODULE from CRY- TUR, spol. s r.o., was tested for future application in Kerr microscopy. The technical solution enabled to form a collimated beam with low divergence required for Kerr mi- croscopy. From the switching experiments on FePt nanograins, we observed a strong non-magnetic contribution to the magnetic signal, not reported in previous works. The experiments have also shown that the switching intensity depends on the laser spot size and total laser power, suggesting that the FePt grains are not entirely isolated. The grains' ensemble exhibits a more complex behavior than anticipated. 1
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