Cette thèse a pour objectif de proposer de nouvelles approches d'ordonnancement, de coopération et de gestion de la mobilité dans les réseaux sans fil de type IEEE 802.11. Le maintien de la qualité de service (QoS), au niveau MAC, représente la caractéristique fondamentale de ces approches. L'analyse des mécanismes existants nous a conduits à retenir le protocole EDCF, supportant la QoS, comme une base de travail pour l'ensemble de nos propositions. Dans le but de pallier certaines faiblesses du standard 802.11, une nouvelle architecture à base de multi-ordonnanceurs HCF-T, est proposée. Les performances obtenues sont exprimées en termes de gestion du trafic, de maintien du débit, d'élimination de collisions et de réduction de la charge du réseau. Ensuite, un schéma coopératif est présenté et analysé. Il comporte une étude de deux protocoles de relayage AAF et DAF ainsi qu'une évaluation d'un ensemble de techniques de combinaison au niveau du récepteur. Concernant la problématique de la mobilité, nous avons retenu et analysé un scénario prenant en considération les différentes situations rencontrées dans un modèle réel. Un algorithme de résolution multi-couvertures est proposé afin de traiter l'accès dans les zones de recouvrement. Cette étude a mené à distinguer trois régimes de mobilité : faible, moyen et fort. Les performances sont évaluées en fonction des métriques MAC et pour chaque mode de mobilité, un schéma de synthèse est établi / This thesis proposes a new approach relating to the packets scheduling algorithm, the cooperation scheme and the nodes' mobility for IEEE 802.11 wireless network family. Considering the QoS delivery process at the MAC level consists the main feature of the proposal research study. The analysis of the current mechanisms leads to keep the protocol EDCF as the basic model for our work platform. In order to overcome the weakness of the earlier 802.11 standard, a new model based on multi-scheduler algorithm, called HCF-T, is proposed. The achieved performances are summarized following several criteria: traffic control, throughput improving, collisions avoidance, and network load decreasing. Furthermore, in the way of getting better results according to the PHY layer, we presented and analyzed a model of cooperative diversity scheme. It included a couple of relaying protocols AAF and DAF supported by a set of combining techniques to backup the signal at the receiver. To support node's mobility within EDCF, we built-up a model of WLAN which able to track node motion and control the access as in real condition. In the case of overlapping APs ranges, we developed a Multi-coverage algorithm aiming to carry out the session associations. As a result, three levels (Low, Medium, and High) of node's speed are discerned. Finally, EDCF has been implemented on various static and dynamic scenarios. The performances, based on the main MAC-layer metrics, such as throughput, End-2-End delay, and jitter, have been classified and comprehensively evaluated

Aproximadamente 40% dos casos de Linfoma não Hodgkin (LNH) se originam fora dos linfonodos, sendo então denominados linfomas extralinfonodais. No trato gastrointestinal (TGI), o estômago é o local mais freqüentemente envolvido, representado pelo linfoma MALT e pelo linfoma difuso de grandes células B (LDGCB). No Brasil, apesar da sua freqüência e importância, existem poucos dados epidemiológicos em relação aos linfomas, especialmente no que se refere aos linfomas de origem extralinfonodal. Para avaliar as características dos linfomas primários gástricos em uma população brasileira, 60 casos foram avaliados retrospectivamente. Trinta e oito (63,3%) foram classificados como LDGCB e 22 (36,6%) como MALT. Entre os dois grupos, não houve diferenças significativas em termos de sexo, idade, sintomas dispépticos, sintomas B, presença de massa Bulky, infiltração de medula óssea, estádio, infecção por H. pylori, achados laboratoriais e endoscópicos. Foram adotados diferentes protocolos de tratamento. A taxa de remissão completa foi de 73,1% no LDGCB e de 95% no linfoma MALT. A taxa de sobrevida livre de doença em 7 anos foi de 84,8% no LDGCB e de 94,1% no linfoma MALT. A taxa de sobrevida global em 7 anos foi de 65,7% no LDGCB e de 92,9% em 5 anos no linfoma MALT. Como não conseguimos demonstrar diferenças entre os dois tipos histológicos, concluímos que o diagnóstico histológico correto é essencial para a terapêutica mais adequada. / Approximately 40% of the non-Hodgkins Lymphoma arises outside lymph node tissue, being then termed extranodal lymphoma. In the gastrointestinal tract, gastric is the commonest localization represented by MALT and diffuse large B-cell lymphoma (DLBCL). In Brazil, despite its importance and frequency there are very few epidemiological data concerning lymphomas, specially the extranodal ones. In order to study the primary gastric lymphoma features in a Brazilian population, 60 patients were retrospectively evaluated. Thirty eight cases (63.3%) were classified as DLBCL and 22 (36.6%) as MALT lymphoma. There were no significant differences between the 2 groups in terms of sex, age, gastric symptoms, B symptoms, Bulky disease, bone marrow infiltration, stage, H. pylori infection, laboratory and endoscopic findings. Different treatment methods were adopted. The complete remission rate was 73.1% for DLBCL and 95% for MALT lymphoma. The disease free survival in 7 years was 84.8 for DLBCL and 94.1% for MALT lymphoma. The 7 year overall survival (OS) rate for DLBCL was 65.7% and 5 year OS for MALT was 92.9%. Because we could not demonstrate differences between the two histological groups, we conclude that the correct histological diagnosis is essential for choosing the best therapeutic approach.

A identificação e biópsia do primeiro linfonodo a receber a linfa de uma formação neoplásica, ou seja, do linfonodo sentinela, fornecem informações essenciais para o tratamento e prognóstico de pacientes humanos acometidos por neoplasia. Entretanto, em Medicina Veterinária existem poucos estudos sobre a drenagem linfática dos órgãos e o conceito de linfonodo sentinela ainda não é amplamente aplicado ao tratamento oncológico dos animais. Desta forma, nosso objetivo no presente estudo foi estabelecer um protocolo de aquisição cintilográfica linfática, ou linfocintilográfica, capaz de fornecer informações funcionais e topológicas da drenagem linfática mamária, pois, em cadelas, as glândulas mamárias ainda são uns dos principais órgãos acometidos por neoplasias. Neste estudo, a linfocintilografia foi utilizada para caracterização topológica e funcional in vivo da drenagem linfática de glândulas mamárias sadias de 30 fêmeas da espécie canina (Canis familiares), sem raça definida e peso aproximado de 10 Kg. O radiofármaco [99mTc]-dextran70 foi administrado por via intraparenquimatosa mamária em quatro pontos ao redor da papila (0,1 ml cada), na dose de 18,5 MBq. As imagens foram obtidas em duas seqüências de projeções laterais e ventrais, sendo uma logo após a administração do [99m</SUP Tc]-dextran70 e a outra após uma hora. O radiofármaco administrado nas glândulas mamárias torácicas craniais foi drenado pelos linfocentros torácico ventral e axilar, sendo que em duas destas 5 glândulas (40%) o radiofármaco também foi para o linfocentro cervical superficial. Este resultado foi semelhante para as glândulas torácicas caudais, entretanto, em nenhuma das linfocintilografias destas glândulas o linfocentro cervical superficial foi identificado. A drenagem das glândulas abdominais craniais foi realizada exclusivamente pelo linfocentro axilar. Os linfocentros inguinais superficial e profundo drenaram as glândulas abdominais caudais e inguinais, porém, uma das glândulas abdominais caudais foi drenada também pelo linfocentro cervical superficial e outra pelo linfocentro mediastínico. A técnica linfocintilográfica utilizada possibilitou a identificação de comunicações linfáticas entre os linfonodos axilares próprio e acessório, entre o axilar próprio e o cervical superficial e entre os linfonodos inguinais superficial e profundo. O número de linfocentros e linfonodos, a taxa de drenagem dos linfocentros e seu funcionamento variaram entre as glândulas mamárias e entre os animais. Em conclusão, o protocolo de aquisição linfocintilográfica adotado foi simples, rápido e eficaz para a caracterização da drenagem linfática mamária. As informações topológicas e funcionais obtidas neste estudo poderão ser aplicadas nos procedimentos investigativos como a ultra-sonografia e a biópsia dos linfonodos mamários em pacientes acometidos por neoplasias mamárias, uma vez que os vasos linfáticos representam vias de disseminação para células neoplásicas. / The knowledge of lymphatic drainage has prognostic and surgical value for oncological treatment. Once you know the lymph nodes that drain the organ, you can predict the possible neoplasic cell route and avoid or predict metastasis. The lymphoscintigraphy is not common in Veterinary Nuclear Centers, however this technique has high applicability in oncological studies. During this study, the lymphoscintigraphie was used to characterize topological and functional aspects of lymphatic health mammary drainage in 30 adult mongrel female dogs, 10Kg in weigh. Lymphoscintigraphies were performed immediately after 4 intramammary peripapilare injections (0, 1 ml each) of 18,5 MBq of [99mTc]-dextran70 and one hour later. Animals were imaged by lateral and ventral projections. Cranial thoracic glands were drained by ventral thoracic and axillary lymph centers, but we observed the simultaneous participation of superficial cervical lymph center in 40% of these (2 animals). This result was similar for caudal thoracic mammary glands, but not for cervical lymph center drainage, that was not observed in caudal thoracic glands lymphoscintigraphies. Cranial abdominal glands were drained exclusively by the axillary lymph center. Superficial and deep inguinal lymph centers drained caudal abdominal and inguinal mammary glands, but we observed one superficial cervical lymph center participation in a caudal abdominal mammary gland drainage. Our lymphoscintigraphic technique provided image of lymphatic communication between axillary lymph nodes and between superficial and deep inguinal lymph nodes. The number of lymph centers and lymph nodes, the lymph center drainage rate and functional behavior of each lymph nodes were variable. In conclusion, the lymphoscintigraphic protocol performed was simple, quickly and provided the lymphatic drainage characterization. Technique, topologic and functional information provided by the present study can be applied to understand neoplasic mammary cells dissemination routes, which has prognostic and treatment value for patients. Veterinary centers that have no Nuclear Medicine facilities can use these topologic and functional information of the present study in other diagnostic procedures such as the abdominal ultra-sound and lymph node biopsy of patients with mammary neoplasia.

Linfonodos de 146 bovinos com lesões macroscópicas identificadas como sugestivas de tuberculose pelos Serviços de Inspeção Federal e Estadual de abatedouros do Estado de São Paulo, Brasil, no período de Maio de 2002 à Janeiro de 2004, conservadas em solução de borato de sódio em temperatura ambiente por no máximo 60 dias, negativos nos cultivos de micobactérias nos meios de Lowëstein-Jensen e Stonebrink com descontaminação por Petroff e HPC e conservadas por congelamento, foram submetidos a novos cultivos em Agar Sangue, Agar MacConkey e Agar Saboraud bem como ao exame histopatológico pelas colorações de Hematoxilina-Eosina e Ziëlh-Neelsen. Nos cultivos houve isolamentos de E. faecium, E. faecalis, E. solitarius, S. arlettae e S. epidermidis. Não houve correlação entre as bactérias isoladas e a localização dos respectivos linfonodos. Os exames histopatológicos classificaram 49 animais isentos de qualquer lesão microscópica, 4 positivos para micobactérias sp, 18 fortemente sugestivos para micobactérias sp e 45 como processos atribuídos a outros agentes que não micobactérias. Não houve correlação entre o aspecto histológico dos linfonodos e o tipo de microrganismo isolado. Os microrganismos isolados foram considerados como contaminantes que tiveram acesso aos materiais durante os procedimentos de abate. / Lymph nodes of 146 bovines presenting lesions identified macroscopically as suggestive of tuberculosis by the Federal and State Inspection Services of abbatoirs at the State of São Paulo, Brazil, from May, 2002 to January, 2004, that were preserved in sodium borate solution at room temperature for no longer than 60 days, negative to mycobacteria culturing on Lowenstein-Jensen and Stonebrink media, decontaminated by Petroff and HPC methods and kept frozen, were subjected to new cultivations on blood, MacConkey and Sabouraud agars as well as to histopathological examination by Hematoxilin-Eosin and Ziëlh-Neelsen coloration techniques. E. faecium, E. faecalis, E. solitarius, S. arlettaeand S. epidermidis were isolated by culturing. No correlation between the isolated bacteria and the respective lymph nodes localization was found. The histopathological classification of the animals was: 49 presented microscopically no lesion, 4 were Mycobacterium sp. positive, 18 were strongly suggestive of Mycobacterium sp. and 45 were attributed to agents other than mycobacteria. There was no correlation between the histological aspect of the lymphnodes and the microorganisms isolated. The isolated microorganisms were considered as contaminants that had access to these materials during the slaughter procedures.

There is an emerging class of applications that require long-term tracking and monitoring of mobile entities for characterising their contexts and behaviours using data from wireless sensors. Examples include monitoring animals in their natural habitat over the annual cycle; tracking shipping containers and their handling during transit; and monitoring air quality using sensors attached to bicycles used in public sharing schemes. All applications within this class require the acquisition of sensor data tagged with spatio-temporal information and uploaded wirelessly. Currently there is no solution targeting the entire class of applications, only point solutions focused on specific scenarios. This thesis presents a complete solution (firmware and hardware) for applications within this class that consists of attaching mobile sensor nodes to the entities for tracking and monitoring their behaviour, and deploying an infrastructure of base-stations for collecting the data wirelessly. The proposed solution is more energy efficient compared to the existing solutions that target specific scenarios, offering a longer deployment lifetime with a reduced size and weight of the devices. This is achieved mainly by using the VB-TDMA low-power data upload protocol proposed in this thesis. The mobile sensor nodes, consisting of the GPS and radio modules among others, and the base-stations are powered by batteries, and the optimisation of their energy usage is of primary concern. The presence of the GPS module, in particular its acquisition of accurate time, is used by the VB-TDMA protocol to synchronise the communication between nodes at no additional energy costs, resulting in an energy-efficient data upload protocol for sparse networks of mobile nodes, that can potentially be out of range of base-stations for extended periods of time. The VB-TDMA and an asynchronous data upload protocol were implemented on the custom-designed Prospeckz-5-based wireless sensor nodes. The protocols’ performances were simulated in the SpeckSim simulator and validated in real-world deployments of tracking and monitoring thirty-two Retuerta wild horses in the Doñana National Park in Spain, and a herd of domesticated horses in Edinburgh. The chosen test scenario of long-term wildlife tracking and monitoring is representative for the targeted class of applications. The VB-TDMA protocol showed a significantly lower power consumption than other comparable MAC protocols, effectively doubling the battery lifetime. The main contributions of the thesis are the development of the VB-TDMA data upload protocol and its performance evaluation, along with the development of simulation models for performance analysis of wireless sensor networks, validated using data from the two real-world deployments.

The most important prognostic factor in breast cancer is the presence or absence of metastases in axillary lymph nodes. Frozen section and touch imprint cytology are conventional intra-operative methods used in the detection of metastatic breast cancer with varying sensitivities and specificities. The limitation of these methods led to the development of alternative molecular diagnostic tests, such as GeneSearch, a commercial real-time quantitative Polymerase Chain Reaction (RT-qPCR) assay that allows for an intra-operative diagnosis of metastatic breast cancer. When the GeneSearch assay was discontinued, Metasin was developed as an in-house RT-qPCR replacement assay. Metasin targets the epithelial cell marker cytokeratin 19 (CK19) and the breast marker mammaglobin (MGB) mRNA to confirm the presence or absence of metastatic disease, whilst the reference gene porphobilinogen deaminase (PBGD) acts as a positive control for the performance of the assay. The optimised assay can produce a result within 32 minutes allowing it to be used in the intra-operative setting to detect metastatic breast cancer in sentinel lymph nodes. 154 archived lymph node homogenates that were previously analysed by both GeneSearch and histology in parallel were used to validate Metasin. Out of 154 cases, 148 showed concordance with both GeneSearch and Metasin with 111 cases being negative and 37 cases being positive. There were six discordant cases, four in which only Metasin detected metastases and two in which only GeneSearch picked up metastases. Out of the four Metasin-only positive cases, three were found to be positive on histology after deeper levels were cut in the slices sent for histological assessment. Therefore, one case could not be shown histologically to be positive for metastases. There were two cases that were missed by Metasin but picked up by GeneSearch. One case was positive on histology and the second case negative for histology. The error rate for Metasin was 3.89%. The sensitivity and specificity of the Metasin assay were found to be 95% and 98% respectively, and the positive and negative predictive values were 90% and 98% respectively. These results are comparable to those of GeneSearch. Metasin had an assay time of less than 45 minutes and was operated by biomedical scientists. The results of the validation process were deemed acceptable for the assay to be run live and used in the clinical setting. Metasin continues to provide breast cancer patients at Princess Alexandra Hospital with all the advantages that a molecular intra-operative diagnostic service provides.

O linfonodo é um órgão linfoide secundário que apresenta uma arquitetura altamente organizada com diferentes compartimentos para tipos celulares específicos. Dentre as células estruturais que compõem este órgão, as células estromais como células fibroblásticas reticulares (FRCs) e células duplo negativas (DNCs) parecem ter papel importante na modulação da resposta imunológica e na tolerância periférica. As FRCs são caracterizadas pela expressão de podoplanina (gp38, PDPN) e localizam-se principalmente na zona de células T, enquanto as DNCs (gp38-) apresentam fenótipo, localização e função pouco descritos. Embora estas células tenham sido muito estudadas em modelos murinos os estudos sobre FRCs e DNCs humanas são escassos e, portanto nosso estudo deve contribuir para a compreensão da biologia e a função dessas células, podendo favorecer o conhecimento sobre a eficiência e as disfunções da resposta imune no linfonodo. Com esse intuito, isolamos e caracterizamos fenotípica e funcionalmente as FRCs e DNCs de linfonodos de pacientes com câncer, diverticulite e doadores de fígado. Nossos resultados mostraram a integridade e a distribuição celular no linfonodo. As células aderentes derivadas dos linfonodos estudados preecheram todos os critérios internacionais de caracterização de estroma, e, portanto, foram consideradas células estromais. Através da expressão de gp38 identificamos duas subpopulações de celulas estromais: FRCs (gp38+ e CD31-) e DNCs (gp38- e CD31-) e verificamos que as frequências destas células variam entre as amostras, sugerindo que a doença pode interferir na composição celular estromal dos linfonodos. As duas populações celulares foram estimuladas com citocinas inflamatórias como IFN-y ou TNF-alfa + IL-1beta por 24 e 48 horas e avaliadas quanto à expressão gênica e proteica. Em condições homeostáticas, genes relacionados com a indução e controle da proliferação foram diferencialmente expressos nas FRCs e DNCs, este dado foi confirmado in vitro, uma vez que as FRCs apresentaram maior potencial proliferativo em relação às DNCs. O estímulo com IFN-y induziu aumento de expressão nas DNCs e FRCs para citocinas, quimiocinas, moléculas de histocompatibilidade e moléculas envolvidas na regulação da resposta imunológica. Em resposta ao estímulo com TNF-alfa +IL-1beta, observamos aumento na expressão de moléculas comuns ao estímulo com IFN-?, entretanto, também observamos expressão de moléculas de citocinas, quimiocinas inflamatórias e moléculas de histocmpatibilidade especificamente relacionados a este sinal em ambas as populações. Em conjunto, nossos dados sugerem que DNCs e FRCs apresentam diferenças no perfil de resposta segundo os estímulos inflamatórios aos quais estão expostas, aumentando a expressão diferencial de moléculas envolvidas na regulação positiva e negativa da resposta imune / The lymph node is a secondary lymphoid organ that has a highly organized architecture with different compartments for specific cell types. Among the structural cells that comprise this organ, stromal fibroblastic reticular cells (FRCs) and double negative cells (DNCs) seems to play an important role in modulating the immune response and peripheral tolerance. FRCs are characterized by podoplanin (gp38, PDPN) expression and are located mainly in the T cell zone, while DNCs (gp38-) present phenotype, location and function not well described. Although these cells have been studied in murine models, studies on human FRCs and DNCs are limited and therefore our study should contribute to the understanding of biology and function of these cells and should promote knowledge of efficiency and disorders in the lymph node immune response. For this purpose, we have isolated and characterized phenotypic and functionally lymph nodes derived FRCs and DNCs from patients with cancer, diverticulitis and liver donors. Our results showed lymph node integrity and its cellular distribution. Adherent cells lymph nodes-derived fullfill the international criteria for stroma characterization, and therefore, they have been considered stromal cells. Using gp38 expression we were able to identify two stromal cells subpopulations: FRCs (gp38 + and CD31-) and DNCs (gp38- and CD31-) and found that this cells frequency varies among samples, suggesting that the disease may interfere with lymph nodes stromal cell composition. These two cells populations were stimulated with inflammatory cytokines such as IFN-y or TNF-alfa + IL-1beta for 24 and 48 hours and evaluated for gene and protein expression. In homeostatic conditions, genes involved in the induction and control of proliferation were differentially expressed by FRCs and DNCs, this data has been confirmed in vitro, since the FRCs showed higher proliferative potential compared to DNCs. IFN-y stimulation induced increase DNCs and FRCs expression for cytokines, chemokines, histocompatibility molecules and molecules involved in regulating the immune response.In response to TNF-alfa + IL-1beta stimulation, we observed common molecules expressed by the IFN-? stimulation, however, we also observed expression of cytokines, chemokines and histocompatibility molecules specifically related to this signal in both cells populations. Together, our data suggest that DNCs and FRCs differ in the response profile according to inflammatory stimuli to which they are exposed, increasing the differential expression of molecules involved in the positive and negative regulation of immune response

Due to the steady increased in public transportation demand, there is a need to provide more desirable and user-friendly transit systems. Typically, the public transportation timetables are modeled as an assignment problem, which often has objectives such as reducing the cost of operation, minimizing waiting time between transfer points or improving the quality of performance. This research considers the problem of developing synchronized timetables for bus transit systems with fixed routes when a waiting time limit exist at each transfer stops, for the passengers making connections. The objective of this research is to have maximum number of simultaneous arrivals. Different to previous studies, a simultaneous arrival' has been defined as an arrival of buses of different routes at a transfer point such that the time between these arrivals do not exceed the passenger waiting time range associated with the transfer stop. In other words, at each node, an upper bound and a lower bound are set for the arrivals of two buses and these buses are run within this allowable window. The heuristic developed has been modeled as a mixed integer linear programming problem and applied to some real life problems to evaluate the outcomes. The total number of synchronizations obtained by the model was compared to the maximum possible simultaneous arrivals at each node. Results show that a larger number of simultaneous arrivals are obtained when the waiting time ranges are relaxed. Finally some important applications of the proposed model compared to the existing models are presented.

This thesis consists of a series of internationally published, peer reviewed, conference research papers and one journal paper. The papers evaluate and further develop two modelling methods for use in Information Technology (IT) design and for the educational and training needs of students within the area of computer and network technology. The IT age requires technical talent to fill positions such as network managers, web administrators, e-commerce consultants and network security experts as IT is changing rapidly, and this is placing considerable demands on higher educational institutions, both within Australia and internationally, to respond to these changes.

Recent advances in Micro-Electro-Mechanical Systems (MEMS) and low-power short-range radios have enabled rapid development of wireless sensor networks. Future sensor networks are anticipated to include hundreds or thousands of these devices in many applications, such as capturing multimedia content for surveillance, structural health monitoring, tracking of accidental chemical leaks, machine failures, earthquakes and intrusion detection. With the increase of sensor applications, a number of challenging problems related to the network protocol design has emerged - the most important ones relating to energy efficiency and lifetime maximisation. Techniques devised for sensor networks should deal with a large number of sensors distributed in the field. Wireless sensor nodes are deployed with limited energy reserves, so the networks should operate with minimum energy overhead. In fact, the network should take into account not only individual node's energy efficiency but also consider the global picture, because surviving nodes' energy reserves in a failed network are wasted energy. This thesis examines a node organisation technique to deal with the above challenges. The focus is on improving network lifetime via organising the nodes in a distributed and energy efficient manner. The main goal is lowering wasted energy via energy balancing and exploiting node redundancy in case of node failure. In particular, this thesis proposes Energy Balanced Clustering (EBC) method for node self-organisation where network tasks (such as data aggregation and data forwarding) are shifted to high-energy neighbours to reduce the energy consumption of low energy nodes. After showing how to extend network lifetime by energy balanced node organisation, the effect of redundant node deployments on network lifetime is addressed. Redundant nodes consume energy by performing unnecessary tasks so a method called Self-Calculated Redundancy Check (SCRC) is proposed to deactivate redundant nodes. A deactivated redundant node can be used as a replacement for a failed node. The Asynchronous Failed Sensor node Detection (AFSD) proposed in this thesis uses the data packets exchanged between neighbours to identify failed neighbours. To restore coverage for network holes caused by failed nodes, policies are given for re-activating redundant nodes. Detailed analytical analysis and simulation of the proposed methods demonstrate that by taking into account energy balancing, eliminating redundant tasks and replacing failed nodes sensor network lifetime can significantly be improved.