On associe à chaque variété algébrique définie sur R un complexe de cochaînes filtré, qui calcule la cohomologie à supports compacts et coefficients dans Z_2 de ses points réels. Ce complexe filtré est additif pour les inclusions fermées et acyclique pour la résolution des singularités, et est unique à quasi-isomorphisme filtré près. Il est représenté par la filtration duale de la filtration géométrique sur les chaînes semi-algébriques à supports fermés définie par McCrory and Parusiński, et induit une suite spectrale qui calcule la filtration par le poids sur la cohomologie à supports compacts. Cette suite spectrale est un invariant naturel qui contient les nombres de Betti virtuels. On montre que le produit cartésien de deux variétés nous permet de comparer le produit de leurs complexe de poids et suite spectrale respectifs avec ceux du produit, et on prouve que les produits cap et cup en cohomologie et homologie sont filtrés par rapport à ces filtrations par le poids réelles. / We associate to each algebraic variety defined over R a filtered cochain complex, which computes the cohomology with compact supports and Z_2-coefficients of the set of its real points. This filtered complex is additive for closed inclusions and acyclic for resolution of singularities, and is unique up to filtered quasi-isomorphism. It is represented by the dual filtration of the geometric filtration on semialgebraic chains with closed supports defined by McCrory and Parusiński, and leads to a spectral sequence which computes the weight filtration on cohomology with compact supports. This spectral sequence is a natural invariant which contains the additive virtual Betti numbers. We then show that the cross product of two varieties allows us to compare the product of their respective weight complexes and spectral sequences with those of their product, and prove that the cup and cap products in cohomology and homology are filtered with respect to the real weight filtrations.

Bakgrund: En av de vanligaste aspekterna vid investeringar är att åstadkomma hög avkastning samtidigt som risken hålls på en låg nivå. Risker kopplade till bolag beror på flera olika faktorer varaven anses vara bolagsstorleken. För att vidare nå önskad avkastning har flertalet investeringsstrategier presenterats som sägs ska kunna överavkasta marknaden och vilket kontrasterar den effektiva marknadshypotesen. Genom investeringar i bolag med låga börsvärden, samt i kombination medinvesteringsstrategier, är det av intresse att undersöka huruvida överträffande av marknaden kan ske. Syfte: Denna uppsats har som syfte att analysera om det, på Spotlight Stock Market och First North, under åren 2007–2019, har gått att påvisa existensen av en SBE och huruvida det går att generera en riskjusterad överavkastning i småbolag med hjälp av investeringsstrategier. Metod: För att genomföra denna uppsats användes en kvantitativ design i kombination med endeduktiv ansats. Åtta olika portföljer sammanställdes baserat på storleken hos bolagen samt en investeringsstrategi baserad på låga P/BV-multiplar. Urvalen skedde utifrån Spotlight Stock Market, Large Cap och First North. Resultaten som genererades analyserades utifrån avkastning och riskjusterad avkastning samt statistiska tester i from av t-tester genomfördes. Slutsats: Utifrån resultaten kunde en småbolagseffekt inte påvisas. Portföljerna enbart baserade påbolagsstorlek för Spotlight Stock Market och First North presterade avkastningar som alla var lägre änOMXSPI, dock kunde detta inte säkerställas statistiskt. När investeringsstrategin utifrån låga P/BVmultiplar användes kunde portföljen utifrån Spotlight Stock Market påvisa en högre avkastning än OMXSPI, dock kunde denna inte heller statistiskt säkerställas. Gällande den riskjusterade avkastningen kunde enbart en av portföljerna baserade på Spotlight Stock Market och First Northpåvisa en riskjusterad överavkastning. Portföljerna baserade på Large Cap påvisade både högre avkastning än småbolagsportföljerna samt riskjusterad överavkastning. / Background: One of the most common aspects when investing is to achieve high returns while maintaining the risk at low levels. Risks associated with firms vary due to different factors of which oneis the size. In order to reach satisfactory returns many investment strategies have been presented with the goal of outperforming the market and thus contrasts the efficient market hypothesis. Through investments in firms with low market value of equity, and in combination with other investment strategies, it is of interest to investigate whether outperforming the market is possible. Purpose: The purpose of this study is to analyze whether a Small firm effect on the Spotlight Stock Market and First North during the years 2007-2019 could be proven and if it is possible in combination with investment strategies to generate risk-adjusted returns. Methodology: In order to complete the study a quantitative design in combination with a deductive design was used. Eight different portfolios were compiled based on the size of the companies as well as an investment strategy based on low P/BV-multiples. The samples were chosen from Spotlight StockMarket, Large Cap and First North. The results that were generated were analyzed based on return, risk-adjusted return and statistical test in the form of t-tests. Conclusion: The results from this study show that a Small Firm effect could not be established. The portfolios solely based on company size for Spotlight Stock Market and First North all performed a lower return than OMXSPI, though this could not be statistically confirmed. When an investment strategy based on low P/BV-multiples was used the portfolio based on Spotlight Stock Market showed a return higher than OMXSPI, though this could not be statistically confirmed either. Regarding the risk-adjusted excess return only one of the portfolios based on Spotlight Stock Market and First North could prove a risk-adjusted excess return. The portfolios based on Large Cap both proved a higher return than the small firm portfolios as well as risk-adjusted excess return.

This study investigates the format of crisis communication by analysing a news archive dataset from Krisinformation.se, a Swedish website dedicated to sharing information about crises. The primary goal is to assess the dataset's structure and efficacy in meeting the Common Alerting Protocol (CAP) criteria, an internationally recognised format for emergency alerts. The study uses quantitative text analysis and data preprocessing tools like Python and Power Query to identify inconsistencies in the present dataset format. These anomalies limit the dataset's usefulness for extensive research and effective crisis communication. To address these issues, the study constructs two new datasets with enhanced column structures that rectify the identified problems. These refined datasets aim to improve the clarity and accessibility of information regarding crisis events, providing valuable insights into the nature and frequency of these incidents. Additionally, the research offers practical recommendations for optimising the dataset format to better align with CAP standards, enhancing the overall effectiveness of crisis communication on the platform. The findings highlight the critical role of structured and standardised data formats in crisis communication, particularly in the context of increasing climate-related hazards and other emergencies. By improving the dataset format, the study contributes to more efficient data analysis and better preparedness for future crises. The insights gained from this research are intended to assist other analysts and researchers in conducting more robust studies, ultimately aiding in developing more resilient and responsive crisis communication strategies. / Denna studie undersöker formatet för kriskommunikation genom att analysera ett nyhetsarkiv från Krisinformation.se, en svensk hemsida som är avsedd att dela information om kriser. Det primära målet är att bedöma datasetets struktur och effektivitet när det gäller att uppfylla kriterierna för Common Alerting Protocol (CAP), ett internationellt erkänt format för nödmeddelanden. I studien används kvantitativ textanalys och dataförberedande verktyg som Python och Power Query för att identifiera inkonsekvenser i det aktuella datasetformatet. Dessa anomalier begränsar datasetets användbarhet för omfattande forskning och effektiv kriskommunikation. För att ta itu med dessa frågor konstruerar studien två nya dataset med förbättrade kolumnstrukturer som åtgärdar de identifierade problemen. Dessa förfinade dataset syftar till att förbättra tydligheten och tillgängligheten av information om krishändelser, vilket ger värdefulla insikter om dessa händelsers karaktär och frekvens. Dessutom ger forskningen praktiska rekommendationer för att optimera datasetformatet så att det bättre överensstämmer med CAP-standarderna, vilket förbättrar den övergripande effektiviteten i kriskommunikationen på plattformen. Resultaten visar att strukturerade och standardiserade dataformat spelar en avgörande roll för kriskommunikation, särskilt i samband med ökande klimatrelaterade faror och andra nödsituationer. Genom att förbättra formatet på datasetet bidrar studien till effektivare dataanalys och bättre beredskap för framtida kriser. Insikterna från denna forskning är avsedda att hjälpa andra analytiker och forskare att genomföra mer robusta studier, vilket i slutändan bidrar till att utveckla mer motståndskraftiga och lyhörda strategier för kriskommunikation.

Bolagens vinstutdelning har länge varit omdiskuterad och rönt mycket uppmärksamhet under de senaste årtiondena. Tidigare forskning har påvisat dess relevans ur ett flertal perspektiv, trots detta finns inget enstämmigt svar på vilka faktorer som påverkar bolagens vinstutdelning. Ett relativt nytt forskningsområde avser styrelsens sammansättning och dess relation till bolagens vinstutdelning. Studien utgår ifrån detta forskningsområde för att kunna urskilja hur diverse styrelsevariabler påverkar utdelningsnivåerna. Därför ämnar studien att svara på om styrelsens sammansättning har något samband med de svenska large cap- bolagens vinstutdelning och i så fall hur sambandet ser ut. Studiens syfte är att undersöka om styrelsens sammansättning relaterar, och i så fall hur, med bolagens vinstutdelning på den svenska börsen. Utifrån tidigare forskning och teori har författarna lyckats urskilja följande styrelsevariabler som är relevanta att undersöka: styrelsestorlek, styrelsens oberoende, andel kvinnliga styrelseledamöter, styrelsens ämbetstid, styrelsens aktieinnehav och den verkställande direktörens dualitet. Datan för dessa variabler samlades in manuellt via respektive bolags årsredovisning under en femårsperiod mellan 2010 och 2014. För att kunna besvara studiens frågeställning utgick författarna från ett kvantitativt metodval. Utifrån befintlig teori och tidigare empirisk forskning konstruerades hypoteser över hur respektive styrelsevariabel bör påverka bolagens vinstutdelning. För att kunna avgöra om styrelsens sammansättning påverkar bolagens vinstutdelning utförde författarna en OLS- regression och en robust regression. Därtill tillkom tester för multikollinearitetsproblem och heteroskedasticitet. Baserat på studiens resultat verkar det finnas ett samband mellan styrelsens sammansättning och vinstutdelningens storlek för svenska large cap- bolag. Resultatet indikerar att både styrelsestorlek och andel kvinnliga styrelseledamöter har en positiv påverkan på bolagens vinstutdelning. Resultatet indikerade också att styrelsens oberoende och aktieinnehav samt dualitet har en negativ påverkan på bolagens vinstutdelning. Vidare har styrelsens ämbetstid ingen signifikant relation till bolagens vinstutdelning. Studiens resultat tenderar att kunna förklaras utifrån Principal agentteorin, då många av variablerna påvisade relationer som förväntas i enlighet med denna teori. Avslutningsvis kan dessa resultat vara av intresse för investerare, lagstiftare och svenska bolag.

To meet new regulations and the demand for a more sustainable energy system, the electricity grid will play an important role. Since the grid owners operate in a monopoly environment a regulating authority, the Swedish Energy Markets Inspectorate (Ei), sets a revenue cap that determines their profits. Changes were made for the regulating period 2016-2019, which now states that grid operators no longer can charge their customers with already depreciated grid components. To spur the grid operators to invest in smarter and more efficient technology, Ei also introduced two new economic incentives to make companies decrease their electricity losses and use the grid more evenly. The first aim of this thesis was to investigate how this new regulatory framework affected the grid operators, by performing interviews and sending out a survey. The result showed that the new regulatory decreases the grid operators’ profitability and also affects their investment strategies. The age of a grid has become more important than both efficient use of the grid and voltage quality when considering investments, since age now has a major impact on the profits. The new incentives however, has almost no effect on the way the grid operators act. The second aim of this study was to investigate how much a grid operator could save with these new incentives. A case study were conducted at Upplands Energi, a small local grid operator, and calculations with their usage data were performed in MATLAB. The results showed that load management by installing control equipment on costumers’ heat pumps and thereby decreasing their power peaks, could save money. By connecting 500 customers Upplands Energi could save about 150 000 SEK per year, and with 5 000 customers they could save almost half a million SEK per year.

<p>In society today large corporations are striving to regain the trust, which has been lost dur-ing the many accounting scandals that occurred lately. As a response to minimize the con-flicts countries have introduced codes of corporate governance. It is common knowledge that a company’s stakeholders and shareholders have different knowledge and interest in the company and the annual report is the agent’s main communication channel towards the principals. The Swedish code of corporate governance was implemented in July 2005 in an attempt to reduce the information gap between the managers of the company and the own-ers.</p><p>The purpose of this thesis is to examine if and how the Swedish code of corporate govern-ance has affected the content in annual reports in Sweden. We will evaluate and explain why listed companies have changed the information provided in their annual reports from the year 2001 prior to the codes existence, during the code’s implementation in year 2005, and after the implementation in 2006.</p><p>A deductive method created our research model, which was used as a tool to gather the empirical findings. Agency Theory, Institutional Theory and the Swedish code constitute the foundation for our evaluation of 65 companies’ annual reports from three individual years. Once our research model was created, an explorative and inductive method was used analyse and interpret the empirical findings.</p><p>Our conclusion is that corporate governance information in annual reports has increased, and the implementation of the Swedish code of corporate governance has affected the in-formation provided to the shareholders. Between 2001 and 2005 a rapid growth in infor-mation can be view, while only minor improvement can be found between 2005 and 2006. The Swedish code has been successful in its implementation as stakeholders and share-holders have received more information from the annual reports. However, we are ques-tioning the Swedish code for its extensive dimensions. Some areas of the Swedish code are provided with sufficient guidelines, while others would bring with it improved information to the shareholders by more detailed instructions. Many of the investigated companies have had their corporate governance information reviewed by an external auditor in 2005 and it is unexpected to see that this has been excluded in 2006. The examined companies provide information regarding many of the Swedish code’s rules, but we found the information re-lated to internal control, managing director and attendance at the general meeting insuffi-cient.</p>

Ce travail de thèse a porté sur l’étude d’activités enzymatiques virales impliquées dans la réplication de deux genres viraux : les Flavivirus et les Coronavirus. Dans un premier temps, nous avons étudié des activités enzymatiques impliquées dans la formation de la structure coiffe des ARNm viraux. En effet, du fait de leur cycle réplicatif cytoplasmique, ces virus n’ont pas accès à la machinerie de formation de la coiffe cellulaire et expriment donc une machinerie dédiée. Le processus canonique de formation de la coiffe fait appel à quatre activités enzymatiques, une ARN 5’-triphosphatase, une guanylyltransférase et deux méthyltransférases.Chez les flavivirus, nous avons développé des outils permettant d’identifier l’activité guanylyltransférase ainsi que des essais enzymatiques nécessaires à la caractérisation des activités méthyltransférases. Ces outils nous ont notamment permis d’évaluer l’effet inhibiteur de molécules choisies par des méthodes de criblages virtuels sur les deux activités méthyltransférases de la protéine NS5 nécessaires à la formation de la coiffe.Chez les coronavirus, nous nous sommes intéressés à une activité méthyltransférase impliquée dans la formation de la coiffe et notamment à sa régulation par un partenaire viral. Nous avons démontré que le processus de méthylation de la coiffe suit un ordre obligatoire, initié par la méthylation de la position N7 par la protéine nsp14. Dans une seconde étape, les structures coiffe-0 (7MeGpppA) sont converties en coiffe-1 (7MeGpppA2’OMe) par la protéine nsp16 en complexe avec nsp10. Nous avons démontré que l’activité 2’O-méthyltransférase portée par la protéine nsp16 nécessite une interaction spécifique avec la protéine nsp10 qui joue probablement un rôle d’échafaudage.Dans un second temps, nous avons démontré que l’activité exoribonucléase portée par la protéine nsp14 est également régulée par la protéine nsp10. La stimulation de l’activité passe par une interaction directe entre les deux protéines et il semble que les surfaces d’interaction de nsp10 avec nsp14 et nsp16 soient chevauchantes. Enfin, la caractérisation de l’activité exoribonucléase confirme la possibilité de son implication dans un mécanisme de réparation des erreurs incorporées lors de la synthèse d’ARN par la polymérase virale. / This work focused on enzymatic activities of two RNA virus genera, Flavivirus and Coronavirus.We first studied the mRNA cap synthesis machinery of these viruses. Indeed, as they replicate in the cytoplasm of the infected cell, these viruses encode their own mRNA cap-forming enzymes. The canonical mechanism of cap synthesis uses four enzymatic activities, a RNA 5’-triphosphatase, a guanylyltransferase and two methyltransferases.We tried to identify the guanylyltransferase activity involved in this process for flaviviruses and we developed enzymatic assays to characterize both guanylyltransferase and methyltransferase activities. We used the methyltransferase assay in order to test the inhibitor effect of molecules, selected by virtual screening, on the methyltransferase activities of the NS5 protein involved in the capping process.Concerning coronaviruses, we first focused on the methyltransferase activities of the nsp14 and nsp16 proteins. We have reconstituted the complete SARS-CoV mRNA cap methylation in vitro. We showed that mRNA cap methylation requires a third viral protein, nsp10, which acts as an essential trigger to complete RNA cap-1 formation. The obligate sequence of methylation events is initiated by nsp14, which first methylates capped RNA transcripts to generate cap-0 7MeGpppA-RNAs. The latter are then selectively 2&#8242;O-methylated by the 2&#8242;O-methyltransferase nsp16 in complex with its activator nsp10 to give rise to cap-1 7MeGpppA2&#8242;OMe-RNAs. Then, we took interest in the exoribonuclease activity of the nsp14 protein and found that this activity is also regulated by the same cofactor, the nsp10 protein. The interaction between the proteins is required to observe the stimulatory effect and it seems that the surface areas of nsp10 interacting with nsp14 and nsp16 overlap. The in vitro characterization of the nuclease activity of nsp14 is according with its potential implication in RNA proofreading mechanism.

As capas carbonáticas neoproterozóicas revestem-se de grande importância, uma vez que se formaram no meio a mudanças paleoclimáticas e evolutivas singulares, cujas origens e influências na história subsequente do planeta e da vida ainda não foram devidamente esclarecidas. Este trabalho procurou compreender parte desta história através do estudo da sedimentação estromatolítica associada à capa carbonática representada pela Formação Mirassol DOeste (base do Grupo Araras), que se formou há cerca de 635 Ma, imediatemente após a glaciação Marinoana, representada pela Formação Puga. A pesquisa foi realizada na região de Mirassol DOeste, Mato Grosso, na borda sudoeste do Cráton Amazônico junto a Faixa Paraguai. Foram estudadas características meso e microscópicas dos estromatólitos, bem como das feições sedimentológicas associadas (estruturas tubulares, megamarcas onduladas, megapeloides), em afloramento, amostras cortadas e lâminas petrográficas. A dois metros da base da formação, inicia-se uma sucessão de 10 metros de espessura de boundstones microbianos, caracterizados, petrograficamente, por lâminas alternadamente delgadas e espessas, compostas de peloides (restos micritizados de colônias microbianas) com micrita subordinada e fenestras. Constituem estromatólitos lateralmente contínuos e de morfologia simples. Estromatólitos estratiformes ocorrem ao longo de toda a sucessão, com formas dômicas, de dimensões métricas irregularmente espalhadas lateral e verticalmente, até dois ou três metros do topo da sucessão. Estromatólitos muito irregularmente ondulados, comumente assimétricos, com dimensões decímetros predominam a parte superior e estes estão recobertos por grainstones-packstones peloidais dolomíticos, com megapeloides milimétricos, em estratos marcados por megamarcas onduladas formadas por ondas. A sedimentação microbiana cessou na Formação Mirassol DOeste quando o ambiente de plataforma de baixa energia onde se desenvolvia começou a ser assolado pela ação de ondas de hipertempestades, que penetraram a região com o aumento do nível do mar. Estruturas tubulares verticais, de comprimento até decimétrico e diâmetro estreito (<3 cm), preenchidos, via de regra, por doloesparito maciço, perpassam a laminação estromatolítica principalmente das porções mais altas dos domos. Sugere-se que gênese dessas estruturas tenha sido pela percolação de gases e/ou líquidos derivados da decomposição de matéria orgânica nas esteiras microbianas. / Neoproterozoic cap carbonates are of great importance because they formed during a period of singular paleoclimatic and evolutionary changes, whose origin and influences upon subsequent geological and evolutionary history have yet to be unraveled. This dissertation sought to comprehend part of this story through the study of stromatolitic sedimentation associated with the cap carbonate represented by the Mirassol DOeste Formation (base of the Araras Group), deposited about 635 Ma ago, immediately following the Marinoan glaciation, represented by the Puga Formation. This research was carried out at Mirassol DOeste, Mato Grosso, on the southwest border of the Amazon craton next to the Paraguai fold belt. Meso and macroscopic characteristics of stromatolites and associated sedimentological features (tubular structures, megaripples, megapeloids) were studied in outcrop, cut specimens and petrographic thin sections. Two meters above the base of the formation a 10 m-thick succession of dolomitic microbial boundstones begins, characterized throughout by alternating thin and thick laminae made up of peloids (interpreted as the micritized remains of colonial microorganisms), subordinate dolomicrite, and fenestrae. They make up laterally continuous and morphologically simple stromatolites. Stratiform stromatolites occur throughout the succession, with irregularly scattered meter-sized domes till about two to three meters from the top. Above this point, very irregularly undulated, commonly asymmetric, decimeter-sized stromatolites predominate, and these, in turn, are covered by megaripple-marked dolomitic peloidal grainstones-packstones with millimetric megapeloids. Stromatolitic sedimentation ceased in the previously calm platform environment of the Mirassol DOeste Formation when wave action began to rework bottom sediments as extremely intense storms reached the locale with the rise in sea level. Narrow (<3 cm), vertical tubular structures of decimetric length and filled by massive dolosparite cut stromatolitic sediments, principally in the central portions of domal forms. These structures appear to have formed by the percolation of gas and/or liquids derived from the decomposition of organic material in the microbial mats.

Ischaemic heart disease remains the single leading cause of death throughout the world. Rupture of an advanced atheromatous coronary plaque precipitates the majority of these clinical events, resulting in thrombosis and myocardial infarction. Post-mortem studies have identified thin-cap fibroatheroma (TCFA) as the plaque subtype most prone to rupture with prospective virtual-histology intravascular ultrasound (VH-IVUS) studies linking VH-TCFA to future adverse clinical events. VH-TCFA are however common along the coronary tree with the majority remaining clinically silent, suggesting that factors other than plaque phenotype play an important role in determining rupture and future plaque behaviour. Rupture is thought to occur when the structural stress within the plaque exceeds the material strength of the overlying fibrous cap. Previous histological work has demonstrated that ruptured plaques are associated with higher stress compared to non-ruptured controls, with in vivo VH-IVUS studies linking higher plaque structural stress (PSS) with the presentation of acute coronary syndrome. Wall shear stress (WSS) on the other hand has been implicated in early plaque development and plaque growth suggesting that both PSS and WSS can influence future plaque behaviour. The work presented in this thesis is associated with a number of novel findings. First, it is the only work to demonstrate that in vivo PSS is higher in coronary atherosclerotic plaques with rupture vs. no rupture across a range of plaque subtypes and irrespective of whether analysis of the entire plaque or of regions close to the minimal luminal area is performed. Second, it shows that the pattern and extent of plaque progression and regression defined as an increase and decrease in plaque area, respectively, are associated with specific biomechanical environments at baseline, in the only study that examines the role of both PSS and WSS in this process. More specifically, high PSS is associated with changes consistent with increased vulnerability both in areas of progression and regression. On the other hand, lower WSS at baseline is associated with greater increases in plaque area and burden in areas that progress and with smaller decreases in areas that regress largely due to changes in fibrous tissue. Although the role of WSS in determining future plaque behaviour has been previously examined, this is the first time that this is assessed specifically in areas of progression and regression, particularly important in view of the dynamic nature of atherosclerotic plaques. More importantly, the work presented in this thesis demonstrates that the interplay of these biomechanical forces is associated with specific patterns of plaque progression and regression despite the fact that PSS and WSS are independent of each other. This has never been previously demonstrated and further suggests that incorporation of biomechanical analysis can play role in the identification of plaques that lead to future clinical events. Finally, the ability of PSS to identify plaques that lead to adverse clinical events was assessed through a propensity core matched analysis of the PROSPECT (A Prospective Natural-History Study of Coronary Atherosclerosis) study. The analysis presented here is the largest, most extensive and thus most significant work to ever examine this with results suggesting that incorporation of PSS and associated parameters can improve the capability of VH-IVUS to identify plaques that lead to such events. In summary, the results of this thesis suggest that coronary PSS plays an important role in the pathophysiology of plaque rupture, and that its incorporation in routine plaque assessment may improve our current ability to identifying coronary plaques that lead to future adverse clinical events. The interplay between PSS and WSS may also affect future plaque behaviour and in particular progression and regression. Prospective studies are now required to fully evaluate the role of these biomechanical forces in plaque development, and whether their incorporation in plaque evaluation can be of clinical significance.

Neste trabalho foi desenvolvido um Espectrômetro de Correlação Angular Gama- Gama Perturbada Diferencial em Tempo (CAP) constituído por seis detectores cintiladores de BaF2, para realização de medidas de interações hiperfinas (campo hiperfino magnético e gradiente de campo elétrico) em diversos materiais e propiciar estudos na área da física da matéria condensada. O espectrômetro desenvolvido possui um sistema de aquisição não convencional em comparação aos demais equipamentos destinados a medidas de CAP. Ao invés do tradicional Analisador Multicanal (MCA), este espectrômetro utiliza um sistema de aquisição de dados constituído, basicamente, por um Conversor Analógico Digital (ADC) rápido, uma placa digital (I/O) convencional e um roteador construído no laboratório de Interações Hiperfinas (LIH) do IPEN. Este versátil e eficiente sistema, controlado por um software também criado no LIH em LabVIEW, permite a geração simultânea de 30 espectros de coincidências &gamma; - &gamma; atrasadas, número superior em comparação aos 12 espectros do antigo espectrômetro de quatro detectores. Além de medidas de linearidade, resolução em tempo e tempo morto, o funcionamento e o desempenho do espectrômetro foram comprovados através de medidas de CAP utilizando os núcleos de prova 111In -> 111Cd e 181Hf -> 181Ta, cujos resultados são bem conhecidos da literatura. Foram feitas medidas de interação quadrupolar do 181Ta em háfnio metálico e do 111Cd em cádmio metálico, e de campo hiperfino magnético do 111Cd e do 181Ta em níquel. Os resultados destas medidas se mostraram em concordância com a literatura. Adicionalmente foram realizadas medidas inéditas de interações hiperfinas magnéticas no composto intermetálico LaMnSi2 utilizando os núcleos de prova 111Cd e 140Ce. As medidas foram realizadas na faixa de temperatura de 10 K a 400K. No caso das medidas utilizando a sonda 111In -> 111Cd, os resultados mostram uma variação do campo magnético com a temperatura que segue a função de Brillouin. Já no caso das medidas com o núcleo de prova 140La -> 140Ce, o resultado apresentou um comportamento anômalo do campo hiperfino em função de temperatura. Os resultados evidenciam uma forte hibridização da banda 4f do Ce com a banda 3d do Mn, fato verificado e estudado em trabalhos anteriores com compostos semelhantes. / In this work a Perturbed gama-gama Angular Correlation (PAC) spectrometer was constructed consisting of six BaF2 scintillator detectors to perform measurements of hyperfine interactions (magnetic hyperfine field and electric field gradient) in different materials to study condensed matter physics. The spectrometer developed has an unconventional acquisition system compared to other equipment for PAC measurements. Instead of a traditional multichannel analyzer (MCA), the spectrometer utilizes a data acquisition system consisting of basically a fast analog to digital converter (ADC), a conventional digital card (I/O) and a router constructed in the hyperfine interactions laboratory (LIH) of IPEN. This versatile and efficient system, controlled by software, also developed in the LIH using LabVIEW, allows simultaneous generation of 30 delayed &gamma; - &gamma; coincidence spectra compared to 12 spectra in the old 4 detector spectrometer in our laboratory. In addition to the tests of system linearity, time resolution and dead time, the operational performance of this spectrometer was demonstrated by PAC measurements using 111In -> 111Cd and 181Hf -> 181Ta nuclear probes, for which the results are well known from the literature. The quadrupole interaction of 181Ta in metallic hafnium, and 111Cd in metallic cadmium, and magnetic hyperfine field of 111Cd in nickel, were measured and the results are in agreement with the literature. Additionally the measurements were carried out, with the new spectrometer, to study the hyperfine field in the intermetallic compound LaMnSi2 using 111Cd and 140Ce nuclear probes. The measurements were carried out in the temperature range from 10 K to 400 K. While the temperature dependence of hyperfine field measured with 111In -> 111Cd probe, follows the Brillouin function the behaviour of the hyperfine field measured with 140La -> 140Ce is anomalous. This behavior has been explained in terms of a strong hybridization of 4f band of Ce with the 3d band of Mn, a fact verified in previous studies with similar compounds.