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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
371

Détection Optique Homodyne: application à la cryptographie quantique

Xu, Qing 28 April 2009 (has links) (PDF)
Les réseaux et systèmes de télécommunications mondiaux fondent aujourd'hui leur confidentialité sur la cryptographie classique, qui repose sur des hypothèses mathématiques fragiles. La distribution quantique de clef (QKD) est aujourd'hui la seule façon connue pour distribuer des clefs avec une sécurité inconditionnelle. Ce travail de thèse contribue à combler de manière pluridisciplinaire et polyvalente le gap entre les limites physiques fondamentales et l'implémentation expérimentale, en termes de vitesse, fiabilité et robustesse. Dans un premier temps, nous avons donc proposé une implémentation du protocole BB84 utilisant les états de phase cohérents. Le récepteur homodyne a été conçu de manière à compenser les fluctuations de phase et de polarisation dans les interféromètres, ainsi que dans le reste du canal de propagation. Ensuite, nous avons mis en place un dispositif expérimental de système QKD à la longueur d'onde 1550 nm, avec une modulation QPSK fonctionnant avec un trajet et un sens de parcours uniques, dans une fibre optique mono-mode. Les deux schémas de détection: le comptage de photons (PC) et la détection homodyne équilibrée (BHD) ont été mis en œuvre. Enfin, nous avons effectué des comparaisons théoriques et expérimentales de ces deux récepteurs. Le récepteur BHD a été élaboré avec une décision à double seuil. La mise en œuvre d'un tel processus accepte des mesures non-conclusives, et réduit l'efficacité de génération des clés, mais reste encore bien meilleur que celle des PCs à 1550 nm. Nous avons également prouvé que ce système est robust sous la plupart des attaques potentielles.
372

Exploring the project management community paradigm and the role of performance prediction

Halliburton, Richard January 2014 (has links)
‘Project performance’ is the metric of delivering project objectives. This research is motivated by levels of project failure and the purpose of the research is to investigate improved project performance. The scientific spectrum is considered; arguing project management as a sub-field of management science based in ‘design science’. Despite research since the 1950s, there is no established community paradigm for project management, illustrated by multiple ‘schools of thought’ failing to stimulate performance improvement. This is investigated with respect to the changing nature of projects and their management; application in numerous industrial sectors, across increasing scope of the product lifecycle (including service projects), and the changing role of project managers as value adding ‘implementers’ rather than status ‘reporters’. Methodology examines the community paradigm and identifies the lack of community paradigm and argues that gap spotting is not appropriate. Conducting research that fills knowledge gaps does not identify underlying issues and reinforces fundamental failings. Underlying assumptions are identified and challenged. Key characteristics are examined in the context of requirements of the community paradigm. The purpose of theory is to describe, explain and predict. Some techniques describe and explain. Few, if any, predict. This locates ‘performance prediction’ as the research issue and suggests it is a missing function for performance improvement. The research focus considers single tasks within a project network. A research model of early stage deviation from plan is developed from the literature on project pathogens and incubation processes. ‘Deviation lifecycle’ as a project function is identified as having no previous evidence in literature. This is developed into a practice model extending the role of failure modes and effects analysis (FMEA) and integrating weak signals and tipping point theory to test performance. Case studies examine representative application of the model and build on the previous cases to illustrate potential for practice. The case studies were reviewed by industrial experts. The changing role of project managers to value added implementers implies a need to improve performance. Research found potential to understand and predict early stage deviation and develops the deviation lifecycle and research model. Across the case studies the research model illustrated potential application. Practical implications indicate potential contribution of project management techniques based on prediction rather than traditional reporting. Developing the community paradigm based on design science is discussed as further work. The originality of the research challenges the lack of theoretical foundation for project management by discussion of the community paradigm and proposes design science as a candidate. The work identifies ‘prediction’ as a relevant but missing function from the project management ‘toolbox’, and introduces the concept of the deviation lifecycle and note no previous literature. The research develops an industrial research model that extends the application of FMEA to examine ‘performance’ and integrates weak signals and tipping point analysis to manage the resolution.
373

Quasilinear PDEs and forward-backward stochastic differential equations

Wang, Xince January 2015 (has links)
In this thesis, first we study the unique classical solution of quasi-linear second order parabolic partial differential equations (PDEs). For this, we study the existence and uniqueness of the $L^2_{\rho}( \mathbb{R}^{d}; \mathbb{R}^{d}) \otimes L^2_{\rho}( \mathbb{R}^{d}; \mathbb{R}^{k})\otimes L^2_{\rho}( \mathbb{R}^{d}; \mathbb{R}^{k\times d})$ valued solution of forward backward stochastic differential equations (FBSDEs) with finite horizon, the regularity property of the solution of FBSDEs and the connection between the solution of FBSDEs and the solution of quasi-linear parabolic PDEs. Then we establish their connection in the Sobolev weak sense, in order to give the weak solution of the quasi-linear parabolic PDEs. Finally, we study the unique weak solution of quasi-linear second order elliptic PDEs through the stationary solution of the FBSDEs with infinite horizon.
374

An Isomorphism Theorem for Graphs

Culp, Laura 01 December 2009 (has links)
In the 1970’s, L. Lovász proved that two graphs G and H are isomorphic if and only if for every graph X , the number of homomorphisms from X → G equals the number of homomorphisms from X → H . He used this result to deduce cancellation properties of the direct product of graphs. We develop a result analogous to Lovász’s theorem, but in the class of graphs without loops and with weak homomorphisms. We apply it prove a general cancellation property for the strong product of graphs.
375

Vyjadřování záhodnosti modálními slovesy "should", "shall" a "be supposed to" a jejich překladové protějšky v češtině / The weak obligation expressed by "should", "shall" and "be supposed to" and their Czech translational counterparts

Tomšová, Karolina January 2016 (has links)
The MA thesis focuses upon the meaning of weak obligation expressed by the modal verbs should, shall and be supposed to and their translation counterparts. The aim of the thesis is to describe the range of translation counterparts of the verbs should, shall and be supposed to and to specify the differences between these verbs in this particular use of weak obligation. The present thesis applies the method of bidirectional corpus-supported approach (Malá, 2013) which helps to determine the differences in meaning between the respective verbs. The most typical Czech counterpart, the verb mít, is further analysed according to its English correspondences. With the help of both directions, the differences in meaning of should, shall and be supposed to are defined. The empirical part of the MA thesis is based on the sample of 250 examples, comprising 50 examples of each modal verb as well as 100 examples of their typical Czech counterpart, the verb mít. The examples are drawn from the Parallel corpora InterCorp. Keywords: modality, weak obligation, should, shall, be supposed to
376

Caracterização molecular de antígenos RhD variantes em doadores de sangue da Fundação Hemocentro de Brasília - Distrito Federal / Molecular characterization of variant RhD antigens in blood donors of the blood Center Foundation of Brasília - Federal District

Mafra, Ana Luisa Alves 04 June 2019 (has links)
Introdução: O sistema de grupo sanguíneo Rh é altamente complexo e polimórfico sendo considerado, depois do sistema ABO, o sistema de maior significado clínico na medicina transfusional. Os anticorpos dirigidos contra os seus antígenos estão envolvidos em reações hemolíticas transfusionais, anemia hemolítica autoimune e doença hemolítica do feto e neonatos. O antígeno D é o mais imunogênico dos antígenos do sistema Rh e sua conformação na superfície das hemácias está disposta como um mosaico de diferentes epítopos. Alterações no gene RHD, que expressa a proteína RhD, podem ser detectadas pela variação na intensidade da reação sorológica, utilizando-se diferentes reagentes anti-D. As alterações ocorrem por diversos mecanismos genéticos e são responsáveis pelo aparecimento dos fenótipos D fraco e D parcial. Essas variantes podem apresentar mudanças qualitativas e/ou quantitativas na proteína RhD e estão frequentemente envolvidas em casos de aloimunização anti-D. A identificação e classificação dos fenótipos RhD variantes possuem alta relevância clínicae, portanto, requerem uma rigorosa investigação molecular, uma vez que os testes sorológicos não são capazes de distinguir entre fenótipos D fraco e D parcial. Dessa forma, esclarecer os resultados fracos ou discrepantes encontrados na sorologia e determinar as variantes RhD têm grande importância para a comunidade científica e, principalmente, para a medicina transfusional. Objetivos: Caracterizar, por métodos moleculares, antígenos RhD variantes em amostras de doadores de sangue da Fundação Hemocentro de Brasília que apresentaram fraca expressão do antígeno RhD. Métodos: Foram selecionadas para extração de DNA e investigação molecular de antígenos RhD variantes 103 de 7983 amostras de doadores de sangue que apresentaram tanto resultados negativo, inconclusivo ou fraco (menor que 2 cruzes) na fenotipagem RhD, realizada por técnica em microplacas, como resultado positivo na confirmação de D fraco. Inicialmente, as amostras foram confirmadas quanto à presença do gene RHD por PCR multiplex RHD regiões íntron4/éxon7. Na sequência, técnicas de PCR alelo específico e RFLP foram utilizadas para triar as variantes D fraco tipos 1, 2, 3 e 4 ou DAR, seguido do sequenciamento de éxons específicos do gene RHD para investigação das demais variantes. As amostras foram avaliadas quanto à zigosidade por dosagem do gene RHD, por qPCR, e quanto à presença do Pseudogene (RHD?) e da deleção do gene RHD, por PCR-SSP. Os resultados encontrados foram interpretados em conjunto com os fenótipos RhCE também analisados. Resultados: Das amostras estudadas, 68,93% foram caracterizadas como RhD parcial; 21,36% como RhD fraco; 1,94% não apresentaram polimorfismos nos éxons do gene RHD e 2,91% apresentaram ausência de éxons RHD indicando a presença de um gene híbrido RHD-CE-D não definido. Entre as amostras RhD fraco, 16,5% eram RHD*fraco tipo 3; 5,8% RHD*fraco tipo 2; 1,94% RHD*fraco tipo 1; 0,97% RHD*fraco tipo 38 e 0,97% RHD*fraco tipo 145. Entre as amostras RhD parcial, 33,01% eram RHD*DAR 3.1; 32,04% RHD*DAR 1.2; 1,94% RHD*DVII; 0,97% RHD* DOL 1; 0,97% RHD* DOL 2. Discussão e conclusão: Nossos resultados demonstraram que as reações atípicas nos testes sorológicos para o antígeno RhD são indicativas da presença de variantes RhD. Os alelos RHD*DAR subtipos foram os mais frequentemente encontrados nas amostras dos doadores de Brasília-Distrito Federal. Esses alelos estão associados à aloimunização anti-D. A caracterização de antígenos RhD variantes por meio da associação de testes sorológicos e métodos moleculares visa, principalmente, determinar os fenótipos/genótipos associados à aloimunização anti-D. Essa caracterização é muito importante para aumentar a segurança transfusional, diminuir a administração desnecessária de imunoprofilaxia anti-D em gestantes e pode, também, colaborar com a preservação dos estoques escassos de unidades de sangue RhD negativo. Além disso, o conhecimento sobre a frequência e distribuição das variantes Rh contribui para a compreensão da origem multirracial da região estudada e auxilia no desenvolvimento de futuros protocolos de genotipagem RHD que estabeleçam estratégias de buscas de unidades de sangue compatíveis para pacientes portadores de variantes RhD. / Introduction: The Rh blood group system is highly complex and polymorphic, and considered, after the ABO system, the system of greater clinical significance in transfusion medicine. Antibodies directed against its antigens are involved in hemolytic transfusion reactions, autoimmune hemolytic anemia and hemolytic disease of the fetus and newborn. Antigen D is the most immunogenic of the Rh system and its conformation on the surface of red blood cells is a mosaic of different epitopes. Changes in the RHD gene, which expresses the RhD protein, can be detected by variations in the intensity of the serological reaction by using different anti-D reagents. The changes occur as a result of several genetic mechanisms and are responsible for the appearance of weak D and partial D phenotypes. These variants may exhibit qualitative and/or quantitative changes in RhD protein and are often involved in anti-D alloimmunization. The identification and classification of variant RhD phenotypes are of high clinical relevance. Therefore, they require a rigorous molecular investigation, since serological tests are not able to distinguish between weak D and partial D phenotypes. Thus, clarifying the weak or discrepant results found in serology and determining RhD variants are of great importance to the scientific community and especially to transfusion medicine. Objectives: To characterize, by molecular methods, variant RhD antigens in donor blood samples from the Blood Center Foundation of Brasília which showed poor expression of the RhD antigen. Methods: A total of 103 out of 7983 samples from blood donors who had negative, inconclusive or weak results (less than 2 crosses) in the microplate technique and also tested positive in the weak D confirmation test were selected for DNA extraction and molecular investigation of the RhD antigen. Initially, the presence of the RHD gene was confirmed in the samples by PCR multiplex RHD intron4/exon7 regions. Then, allele specific PCR and RFLP techniques were used to screen for weak D variant types 1, 2, 3 and 4 or DAR, followed by sequencing of specific exons of the RHD gene to investigate the other variants. Samples were evaluated for zygosity by RHD gene dosage by qPCR and for the presence of Pseudogene (RHD?) and RHD gene deletion by PCR-SSP. The results were interpreted in conjunction with the RhCE phenotypes also analyzed. Results: Of all samples studied, 68.93% were characterized as partial RhD; 21.36% as weak RhD; 1.94% had no polymorphisms in the RHD gene exons and 2.91% had no RHD exons indicating the presence of an undefined RHD-CE-D hybrid gene. Among the weak RhD samples, 16.5% were weak RHD*type 3; 5.8% RHD * weak type 2; 1.94% RHD*weak type 1; 0.97% RHD*weak type 38 and 0.97% RHD* weak type 145. Among the partial RhD samples, 33.01% were RHD*DAR 3.1; 32.04% RHD*DAR 1.2; 1.94% RHD*DVII; 0.97% RHD*DOL 1; 0.97% RHD*DOL 2. Discussion and conclusion: Our results demonstrated that atypical reactions in serological tests for the RhD antigen are indicative of the presence of RhD variants. The RHD*DAR subtype alleles were the most frequently found in donor samples from Brasília - Distrito Federal. These alleles are associated with anti-D alloimmunization. The characterization of variant RhD antigens through the association of serological tests and molecular methods mainly aims to determine the phenotypes/genotypes associated with anti-D alloimmunization. This characterization is very important to increase transfusion safety, reduce unnecessary administration of anti-D immunoprophylaxis in pregnant women and may also contribute to the preservation of scarce RhD negative blood units. In addition, knowledge about the frequency and distribution of Rh variants contributes to the understanding of the multiracial origin of the studied region, and assists in the development of future RHD genotyping protocols that establish compatible blood unit search strategies for RhD variant patients.
377

Mat- och tekniknytt : Kommunikation och informationsspridning för ökad innovation inom gotländska livsmedelsförädlingsindustrin

Axner, Tom, Zetterlund, Philip January 2019 (has links)
Hållbarhet är ett ämne som konstant är på dagens agenda. Många länder gör idag omställningar föratt nå de uppsatta klimatmålen inom FN, EU och på en nationell nivå. Gotland Grönt Centrum är enaktör på Gotland som genom sitt projekt “Ökad livsmedelsförädling” drar sitt strå till stacken för att ökaden hållbara utvecklingen på ön. Gotland Grönt Centrum vill öka kunskapsspridningen ochinnovationsgraden inom den gotländska livsmedelsförädlingsindustrin genom att upprätta enFacebooksida där aktörer kan mötas. Forskningsfrågan för uppsatsen är därför fokuserad på hurkommunikationen bör se ut för att nå de uppsatta målen i GGC:s projekt. Genom en kvalitativ studieämnar denna uppsats besvara forskningsfrågan genom teorier om social network theory,sensemaking, strukturella hål med flera för att sedan mynna ut i en slutsats. Genom en kodning avempirin kunde analysen visa flera aspekter som är vitala för att GGC ska kunna föra en framgångsrikkommunikation för att nå sina mål. Svaret blev att genom att arbeta med sensemaking för att formasitt budskap efter målgruppen kan engagemanget gentemot projektet öka. Detta kan leda till eninstitutionalisering och gemensam förståelse, vilket kan leda till framtida samarbeten mellan aktörer.Innovationsgraden kan dessutom öka ifall GGC antar en roll som länk och gränsöverskridare inomnätverket för att överbrygga strukturella hål och således få in ny information i flödet. / Sustainability is a topic that is constantly on the agenda of today. Many countries today are makingadjustments to achieve the set climate goals within the UN, the EU and at a national level. GotlandGrönt Centrum is an regional actor on Gotland, which through its project "Increased food processing"aim to increase the sustainable development on the island. Gotland Grönt Centrum wants to increasethe dissemination of knowledge and the degree of innovation within Gotland’s food processingindustry by establishing a platform where players can meet. The research question for the essay istherefore focused on how the communication should be formulated to achieve the set goals in theGGC project. Through a qualitative study, this paper aims to answer the research question throughtheories of social network theory, sensemaking, structural holes, and more, in order to draw aconclusion. Through the coding of the empirical data, the analysis could show several aspects thatare vital for GGC to be able to conduct successful communication in order to achieve its goals. Theanswer was that by working with sensemaking to shape their message according to the target group,the commitment to the project can increase. This can lead to institutionalization and mutualunderstanding, which can lead to future collaboration between actors. The degree of innovation canalso increase if GGC assumes a role as a link and boundary spanner within the network to bridgestructural holes and thus bring in new information in the flow.
378

Garbage Collection for Java Distributed Objects

Dancus, Andrei Arthur 02 May 2001 (has links)
We present a distributed garbage collection algorithm for Java distributed objects using the object model provided by the Java Support for Distributed Objects (JSDA) object model and using weak references in Java. The algorithm can also be used for any other Java based distributed object models that use the stub-skeleton paradigm. Furthermore, the solution could also be applied to any language that supports weak references as a mean of interaction with the local garbage collector. We also give a formal definition and a proof of correctness for the proposed algorithm.
379

Essays in exchange rates and international finance

Mirkin, Lorice January 2018 (has links)
This thesis pertains to international finance and models of exchange rate determination as well as efficiency of the market for foreign currency. The first chapter is an introduction where we discuss the advent of flexible exchange rate regimes and the development of monetary models of exchange rate determination as well as present a framework for this thesis. In the second chapter we consider the historical failure of monetary models of the exchange rate and revisit the standard real interest differential (RID) model (Frankel, 1979a). The Great British Pound (GBP) and Canadian Dollar (CAD) vis-à-vis the United States dollar (USD) are examined during the period 1980:Q1 -2015:Q1, a time characterized by flexible exchange rate regimes and heightened capital mobility across borders. Unit root properties of the sample variables are examined and the Johansen (1995) methodology is applied to test for cointegration. The RID model yields a single cointegrating relation however tests of long-run exclusion (LE) and weak exogeneity (WE) show that the RID model is not a coherent model of the GBP and CAD against the USD. The study is furthered by examination of the hybrid monetary model (Hunter and Ali, 2014). The hybrid model is tested for comparison with Japan, as the post 2007-2009 financial crisis period is branded by zero-lower bound interest rates, a phenomenon first experienced by Japan for any prolonged period of time. The hybrid model in addition yields a single relation however tests of LE and WE show that the long-run projection is reversed and that a coherent relationship exists between the GBP and CAD vis-à-vis the USD and variables related to monetary fundamentals as well as long-run economic activity. In the third chapter we examine efficiency of the market for foreign currency. The lead-lag pricing relationship between spot and futures rates is discussed and a panel employing data for the GBP, Australia Dollar (AUD), CAD, Brazilian Real (BRL) and South African Rand (ZAR) vis-à-vis the USD is constructed at several intervals prior to expiry. The Johansen (1995) methodology is applied and shows that spot and futures rates cointegrate and that the cointegrating vector is the basis. Unit root properties for the basis are also examined and found to be integrated of order one or I(1). We therefore show that the market for foreign currency functions efficiently and that profitable arbitrage opportunities exist that restore prices to parity levels. This study is of particular significance in view of the markets' growing share and need for greater transparency to lay down appropriate regulation that limits systematic risk. In the fourth chapter we re-examine monetary models of the exchange rate and consider the USD vis-a vis the Japanese Yen (JPY) in view of the Japanese economy's slow growth in the post 2007-2009 financial crisis period. We test the standard RID monetary model as a framework for modelling the USD/JPY exchange rate however tests of WE show that the nominal exchange rate is weakly exogenous so drives the system instead of adapting to it. The hybrid monetary model developed by Hunter and Ali (2014) is adjusted in consideration of the current period of sluggish economic growth in Japan by incorporating differentials related to traded and non-traded goods productivity (Rogoff, 1992). The adjusted hybrid model produces a single cointegrating relation and joint tests of LE and WE show that the nominal exchange rate cannot be long-run excluded and is not weakly exogenous so that the adjusted hybrid model is a coherent long-run model of the USD/JPY nominal exchange rate. In the fifth chapter we conclude and summarize the findings of the three studies presented in this thesis as well as provide practical recommendations for further study such as construction of dynamic error correction models and assessing out-of-sample forecasting performance for the extended monetary models examined in chapters two and four. Further development of the study for effectively functioning foreign exchange markets as presented in chapter three is in addition discussed in the final chapter. We contribute to the extant literature by showing in chapter two that the conventional RID monetary model of the exchange rate for the GBP and CAD vis-à-vis the USD can be rejected. A single econometric specification can be adapted to explain the long-run exchange rate for the GBP/USD exchange rate while an extended model is effective in providing an explanation of the long-run CAD/USD exchange rate. In chapter three we demonstrate that the spot and futures markets for five bilateral exchange rates function effectively across developed and developing countries. Lastly, we show in Chapter four that the model of the USD/JPY exchange rate due to Hunter and Ali (2014) appears a specific case and that the USD/JPY is not readily distinguished from a random walk in the context of a monetary model that considers traded and non-traded goods productivity differentials.
380

Magnetização remanente em sistemas antiferromagnéticos\" / Remanent magnetization in the antiferromagnetic systems

Carvalho, Zulmara Virgínia de 17 March 2006 (has links)
No contexto de sistemas de baixa anisotropia, medidas de magnetização para verificar os efeitos magnéticos induzidos pela substituição do íon Mn+2 por Cu+2 em um quase unidimensional antiferromagneto tipo Heisenberg CsMn1-xCuxA3.2H2O (A = Cl, Br) foram feitas. Nas amostras diluídas com derivados de Br observamos o aparecimento de uma magnetização remanente abaixo de TN quando elas são resfriadas em um pequeno campo axial aplicado ao longo do eixo fácil. Isso não ocorre com as amostras diluídas com derivados de Cl. A troca intra-cadeia tanto com os compostos de Cl e Br é antiferromagnética, entretanto a troca entre-cadeias ao longo de eixo fácil é antiferromagnética no composto com Cl e ferromagnética com o Br. Esse fato parece ser determinístico no surgimento de momentos espontâneos abaixo de TN no composto com bromo. Além disso, medidas de magnetização do monocristal antiferromagnético de sítio diluído A2Fe1-xInxCl5.H2O (A = Cs) foram feitas em baixos campos magnéticos (H) aplicados ao longo do eixo de fácil magnetização. Os dados revelaram que uma magnetização remanente Mr se desenvolve abaixo a temperatura de Néel TN. Essa Mr(T) é paralela ao eixo fácil e satura para campos H ~ 1Oe e ela aumenta com decréscimo de T. Ela também possui uma dependência de temperatura como outros sistemas diluídos da mesma família (A = K, Rb). Para todos esses sistemas, a curva normalizada Mr(t)/ Mr(t = 0,3), onde t=T/TN é a temperatura reduzida, é independente de x e acompanha uma curva universal. No contexto de sistemas de alta anisotropia, a dependência da temperatura do excesso de magnetização em baixos e altos campos foi investigada para o antiferromagneto 3D de Ising FexZn1-xF2 (x = 0.72; 0.46 e 0.31) e também o sistema puro FeF2. Verificamos que Mr surge tanto paralela ou perpendicular ao eixo fácil. A magnitude de Mr, para baixos campos (H < 1 Oe) depende de H, mas satura para campos de alguns Oersted. O esperado comportamento de campo aleatório (RF), em campos altos, é observado quando H é aplicado ao longo do eixo fácil. / In the context of low anisotropy, the magnetization measurements to find out the magnetic effects induced by the substitution of Mn+2 by Cu+2 íons in the quaseone-dimensional Heisenberg-like antiferromagnets CsMn1-xCuxA3.2H2O (A = Cl,Br) were made. In the diluted samples of the Br derivative, we observe the appearance of a remanent magnetization (Mr) below TN when they are cooled in a small axial magnetic field applied along the easy axis. This does not occur in the diluted samples of the Cl derivative. The intra-chain exchange both in Cl and Br compounds is antiferromagnetic, however the inter-chain exhange along the easy axis is antiferromagnetic in the chloride compound and ferromagnetic in the bromide. This fact seems to be deterministic in the appearance of the net moments below TN in the bromide. Moreover, the magnetization measurements on single crystals of the sitediluted antiferromagnet A2Fe1-xInxCl5.H2O (A = Cs) were carried out at low magnetic fields (H) applied along the easy axis. The data revealed that a Mr develops below the Néel temperature TN. This Mr(T) is parallel to the easy axis , saturates for H ~ 1 Oe and it increases with decreasing T. It has also temperature dependence as another diluted systems of the same family (A = K, Rb). For all these systems the normalized Mr(t)/Mr(t = 0,3), where t = T/TN is the reduced temperature, is independet of x and follow a universal curve. In the context of high anisotropy, the temperature dependence of the excess magnetization at low and high fields was investigated for the diluted antiferromagnet FexZn1-xF2 (x = 0.72; 0.46 and 0.31) and pure system FeF2 as well. It was found that Mr is either along the easy axis or perpendicular to it. The size of Mr for very low fields (H < 1 Oe) depends on H but it sature for fields of the order of few Oersteds. The expected random field (RF) behaivor is observed when H is applied along the easy axis at higher fields.

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