Currently, new algorithms are being incorporated into operating systems to deal with a host of new requirements from multimedia applications. These new algorithms deal with soft real-time scheduling, different memory models, and changes to buffer caching and network protocols. However, old design techniques such as structured programming, global variables and implied dependencies are impeding this development and proof of correctness. Many current operating system research groups are developing extensible systems, where new code can be placed into the system and even kernel layers. A primary difficulty in these efforts is how to avoid adversely affecting reliability and traditional measures of performance. Techniques from the object orientation paradigm are being incorporated to better manage these issues because they have shown promise in improving modularity, information hiding, and reusability. In some cases, these techniques are even being used to build fresh operating systems from the ground up with the goal of easier extensibility and adaptability in the future. The Apertos operating system introduced and implemented many concepts originally alien to operating system research but exhibited unacceptable performance for multimedia applications. This dissertation introduces Chameleon, a new object-oriented operating system that shares the same philosophical approach as Apertos, leveraging meta designs and concepts to deal with the diverse requirements of today’s and future multimedia applications. However, Chameleon takes a new and original approach to design and implementation to achieve a high degree of adaptability and retain the performance of a micro-kemel. In Chameleon, the object-oriented paradigm serves as the basis for newly introduced concepts such as AbstractCPU, brokers, and the broker interface hierarchy. Together, AbstractCPU, brokers, and related software engineering techniques such as dynamic class binding serve as a basis for all system management, communication, and for an event-driven model where new events can be defined and dynamically introduced to a running system. The meta design clearly defines a hierarchy of “operating environments” that can be optimized for a particular type of application. As such, hierarchical resource management plays an important role in Chameleon. A minimal set of primitives that is appropriate for hierarchical memory management is defined atop a single address space memory model. Similarly, hierarchical CPU scheduling is employed, as different applications will exhibit different scheduling requirements. Different schedulers may then co-exist on the same CPU. Communication in a hierarchically structured operating system is also detailed. The implementation of the Chameleon structuring concept is presented and analyzed. Standard performance measures are used to compare Chameleon to related research and commercial operating systems. Costs of individual operations are also presented to outline the overheads and gains associated with the Chameleon model. / Graduate

In this tribological study, a temperature dependent inquiry of the changes in chemistry and crystal structure of two selected double metal oxides is undertaken. It is known that chameleon coatings of Mo2N/Ag/MoS2 produce a friction coefficient of 0.1 from wear testing at 600 °C for 300,000 cycles. The low friction is attributed to the formation of silver molybdates layers, a lubricious double-metal oxide, in the coating. Double-metal oxides consisting of a group 6 transitional metal and silver (silver molybdate (Ag2Mo2O7) and silver tungstate (Ag2WO4)) were used for this investigation. Thin films and powders were investigated using high temperature x-ray diffraction, high-temperature Raman spectroscopy and differential scanning calorimetry in tandem with sliding tests from 25 to 600 °C. Our results were compared to external ab-initio molecular dynamic simulations performed elsewhere to qualify experimental results. The layered atomic structure of silver molybdate facilitates sliding, resulting in a low coefficient of friction (<0.2) from 300-500 °C. Unlike Ag2Mo2O7, however, Ag2WO4 does not possess a layered atomic structure and produced coefficients of friction (>0.4) in all temperature ranges between room temperature and 500 °C. Applying the knowledge gained from prior studies of the intrinsic properties of double metal oxides of group 6, chameleon coatings consisting of group 5 transitional metal nitrides (vanadium nitride, niobium nitride, and tantalum nitride) with silver inclusions were created using unbalanced magnetron sputtering to investigate their potential application as adaptive, friction reducing coatings. The coatings were tribotested against a Si3N4 counterface in the 22 to 1000 °C temperature range. In-situ Raman Spectroscopy measurements were taken during heating and wear testing at 700 °C to identify the evolution of phases in the coatings' surfaces and in the wear track. The chemical and structural properties of the coatings were also characterized before and after wear testing using x-ray diffraction. At higher temperatures, oxygen, silver and the transition metals react on the surface to form potentially lubricious double oxide phases (silver vanadate, silver niobate and silver tantalate). All coatings performed similarly up to 750 °C. The VN/Ag coating, however, had a lower coefficient of friction at 750 °C comparatively to TaN/Ag and NbN/Ag, likely due to its reported lower melting temperature (450 °C) and its layered crystal structure.

In the VANET environment, the security of traffic information between vehicles is very important. The messages need to be real-time, and the complexity of authentication should be low. Our proposed method focus on the identity verification based on bilinear pairing, therefore, vehicles, roadside units (RSUs), central authorities (CAs) and trust authority (TA) can verify the identity of each other. After the identity authentication, RSUs will broadcast messages containing chameleon hashing values of verified vehicles, to the other RSUs and vehicles. In the future, vehicles can communicate with the verified vehicles, and verify the messages by these chameleon hashing values. The advantages of the propose method is mainly: 1. Based on the identity-based cryptography (i.e. IBC), the vehicles, RSUs, CAs and TA can verify the message each other. 2. The vehicles can verify the source and legitimacy of the public/private key. 3. The vehicles do not need to show any certificate to verify the identity, avoiding the certificate is exposed for a long time and causing attacks. 4. We can verify the messages through chameleon function and does not need to wait for RSU to verify, it would have good latency performance. 5. We don¡¦t need to re-verify the identity and consult the common keys when the vehicles hand off within the different cover ranges of the RSUs. 6. Not only within the RSUs, our proposal but also can execute in somewhere without RSU. Finally, our proposal method can fulfill the authentication, data integrity, non-repudiation, condition-privacy and untraceable.

Vehicular ad-hoc network (VANETs) has been a hot research topic in recent years. In this environment, each vehicle can broadcast messages to other vehicles and inform drivers to change their route right away in order to enhance the efficiency of driving and to avoid accidents. Since vehicles communicate through wireless tunnel, many malicious attacks may occur during the transmission of messages. Consequently, ensuring the correctness of receiving messages and verifying the authenticity of the sender is necessary. Besides, we also need to protect the real identities of vehicles from revealing to guarantee the privacy. To satisfy these security properties, many related researches have been proposed. However, they all have some drawbacks. For example: 1. The cost of the certificate management and the exposure problem of the certificate. 2. Waiting for RSU to verify the messages: Once more vehicles need RSU, RSU will have much more overhead and it can¡¦t achieve real-time authentication. In this thesis, we come up with an anonymous authentication and key agreement scheme based on chameleon hashing and ID-based cryptography in the vehicular communication environment. In our scheme, every vehicle can generate many different chameleon hash values to represent itself, and others can prove the ownership of chameleon hash value. Furthermore, unlike other pseudonymous authentication schemes, we also achieve one-to-one private communication via ID-based cryptography. Finally, we not only overcome some problems in previous works but also fulfill some necessary security requirements in vehicular communication environment.

Due to the fast progress of the internet technologies, electronic commerce becomes more and more popular. Many people and businesses deal with their transactions via the internet. The technologies of credit cards, electronic tickets, e-cash, and other advanced services have realized the vision of electronic commerce. In this thesis, we propose an off-line e-cash scheme with anonymity, untraceability, double-spending checking, and traceability. Anonymity and untraceability must be possessed in any e-cash scheme. In an off-line e-cash scheme, the bank or the third party (TTP) must be able to revoke the anonymity of a user who doubly spent her/his e-cash(s). In our proposed e-cash scheme, the bank can fast derive the identity of the user who doubly spent her/his e-cash(s) without the participation of TTP. If some illegal transactions are reported, TTP can also directly revoke the anonymity of the user who spent her/his e-cash(s) in the illegal transactions. In addition, the police needs to trace a specific user in some situation, and we propose a process to satisfy this requirement,called traceability.

Improving water use efficiency is included in the Sustainable Development Goals of the United Nations. Ethiopia is a developing country struggling with food production as well as water scarcity. This study presents the results of a statistical analysis of changes in water productivity (i.e. yield versus water usage), wheat yield and irrigation amount by implementation of irrigation scheduling in Koga Irrigation Scheme, north-west Ethiopia. Highest water usage (570 mm), lowest water productivity (0.5 kg m-3) and lowest yield (2800 kg ha-1) were obtained for the control group (i.e. traditional irrigation scheduling, based on experience). All groups which implemented some irrigation scheduling displayed higher water productivity than the control group. The highest water productivity and yield was achieved with a soil moisture sensor (Chameleon) technology, with increases of 58 % and 32 % with respect to the control group, respectively. Nitrogen had a positive effect on both yield and water productivity, however, the interaction effects between applied nitrogen and implemented irrigation scheduling were considered insignificant. This study is concluding that implementation of irrigation scheduling should be a successful approach for improving yield as well as water productivity in Koga. / En förbättrad effektivitet i vattenanvändningen ingår i Förenta nationernas Globala mål för hållbar utveckling. Etiopien är ett utvecklingsland med utmaningar i såväl matproduktion som vattenbrist. Denna studie presenterar resultaten av en statistisk analys av förändringar i vattenproduktivitet (dvs skörd per vattenmängd), skörd och bevattningmängd genom implementering av verktyg för bevattningsplanering i Koga bevattningsområde, nordvästra Etiopien. Högsta vattenförbrukning (570 mm), lägsta vattenproduktivitet (0,5 kg m-3) och lägsta skörd (2800 kg ha-1) erhölls för kontrollgruppen. Alla grupper som infört någon typ av bevattningsplanering visade högre vattenproduktivitet än kontrollgruppen (dvs traditionell bevattningsplanering baserad på erfarenhet). Den högsta vattenproduktiviteten och skörden uppnåddes med en vattenfuktsmätare (Chameleon), med ökningar på 58 % respektive 32 % jämfört med kontrollgruppen. Kväve hade en positiv effekt på både skörd och vattenproduktivitet, men interaktionseffekterna mellan kväve och de implementerade bevattningsplaneringarna ansågs försumbara. Denna studie drar slutsatsen att införandet av någon typ av bevattningsplanering bör vara ett framgångsrikt tillvägagångssätt för att förbättra skörd samt vattenproduktivitet i Koga. / “Using Remote Sensing in support of solutions to reduce agricultural water productivity gaps” (Capacity development for increasing water productivity) (GCP/INT/229/NET)

L'un des plus grands problèmes ouverts de la cosmologie moderne est l'origine de l'expansion accélérée de l'Univers, découverte en 1998. L'explication théorique la plus simple repose sur l'introduction d'une constante cosmologique $Lambda$. Ce modèle, connu sous le nom de $Lambda$CDM, est en accord avec les différentes observations liées à l'expansion accélérée. Cependant, il présente des problèmes d'ordre théorique. Par conséquent, plusieurs alternatives, connues collectivement sous le nom de {it modèles d'énergie noire}, ont été proposées pour expliquer cette accélération. Plusieurs d'entre eux restent viables, car leurs {it backgrounds} cosmologiques ne présentent pas de signatures identifiables. Par contre, les effets sur les phénomènes perturbatifs sont plus spécifiques à chacun de ces modèles. Dans cette thèse, nous explorons les caractéristiques particulières de la croissance des perturbations de matière à l'ordre linéaire dans les théories $f(R)$ avec un regard complémentaire sur les modèles chameleon. La paramétrisation du taux de croissance de la matière en termes d'une fonction $gamma$ permet d'identifier une signature très spécifique de ces modèles en comparaison avec le modèle $Lambda$CDM. Une étude supplémentaire a permis de trouver une dépendance en échelle explicite, nommée {it dispersion}, dans la croissance des perturbations. Des observations plus précises pourraient permettre de faire la différence entre ces différents modèles selon la présence de ces caractéristiques. / One of the most important open issues in modern cosmology is the origin of the accelerated expansion of the Universe, observed in 1998. The simplest theoretical explanation relies on the introduction of a cosmological constant $Lambda$. This model, known as $Lambda$CDM, agrees with all the different observations connected to the accelerated expansion. However, it presents some theoretical issues. As a result, several alternatives, known collectively under the name of {it dark energy models}, have been proposed to explain this acceleration. Several among them remain viable, since their cosmological backgrounds do not show any identifiable signature. On the other hand, effects on the perturbative level are more specific to each model. In this thesis, we explore the particular characteristics of the growth of linear matter perturbations in $f(R)$ theories, with a complementary look on chameleon models. The parameterization of the growth rate in terms of a $gamma$ function allows us to identify a very specific signature of these models in comparison with the $Lambda$CDM model. A subsequent study allowed us to find an explicit scale dependance, known as {it dispersion}, in the growth of perturbations. More precise observations could enable us to distinguish between dark energy models according to the presence of this type of feature.

Mobile ad hoc networks create communication links without the aid of any infrastructure, forwarding packets among mobile nodes. The MANET research community has identified several fundamental challenges, among which the most prominent is discovering an optimal route between two nodes. Existing work has proposed a plethora of routing protocols. Since each protocol implements its own philosophy and algorithm to target a specific purpose, routing protocols in MANETs show very different characteristics. Selecting a particular protocol for an application or deployment environment involves evaluating many complex inter-dependent tradeoffs and can be an overwhelming task for an application designer. However, this decision can have a significant impact on the success of a system in terms of performance, cost, and responsiveness. Emerging distributed applications deployed in MANETs inherently experience highly dynamic situations, which necessitate real-time routing protocol selection in response to varying scenarios. Most of the relevant research in this area relies on simulation studies or empirical analysis to select a routing protocol, requiring an infeasible amount of time and resources for the approaches to be used in real-time decision making. In my dissertation work, I designed the Chameleon framework to facilitate real-time routing protocol decisions based on given application and environmental characteristics. My approach develops analytical models for important network layer performance measures capturing various inter-dependent factors that affect routing protocol behavior. I provide an analytical framework that expresses protocol performance metrics in terms of environment-, protocol-, and application-dependent parameters. This effort has resulted in detailed models for two important metrics: end-to-end delay and throughput. I specify detailed models for the parameters embedded in the models with respect to the ability of network deployers, protocol designers, and application developers to reasonably provide the information. Finally, in a systematic manner, I outline the Chameleon software framework to integrate the analytical models with parameters specified by these three groups of stakeholders. / text

In der vorliegenden Arbeit wurden 212 Kotproben von Chamäleons auf Parasitenstadien und 75 Tierkörper pathologisch sowie bei einem nachgewiesenen Parasitenbefall histopathologisch untersucht. Ziel war es, anhand dieser Untersuchungen das Vorkommen und die Schadwirkungen von Endoparasiten unter Berücksichtigung der Herkunft, des Alters, des Geschlechts und der Chamäleonart zu beschreiben. Von 212 Kotproben wiesen 55,2% Endoparasitenstadien auf. Bei 54,7% der 64 sezierten und auswertbaren Tiere wurden Endoparasiten nachgewiesen. Der Anteil positiver Proben zeigt zwischen Nachzuchten (55,5%) und Wildfängen (54,1%) keinen wesentlichen Unterschied. In Wildfängen konnten häufiger Endoparasiten mit einem indirekten Lebenszyklus ermittelt werden, Nachzuchten beherbergten dagegen öfter Parasiten mit einem direkten Entwicklungszyklus. In den untersuchten Chamäleons konnten regelmäßig Kokzidien der Gattung Isospora und Oxyuriden nachgewiesen werden. Zestoden konnten in der koproskopischen Untersuchung gar nicht aufgefunden werden, wohingegen sie in der pathologischen Untersuchung sporadisch im Darm diagnostiziert werden konnten. Die Häufigkeit des koproskopischen Nachweises von Parasitenstadien bezogen auf die Gesamtzahl der untersuchten Chamäleons stellte sich wie folgt dar: in 30,4% wurden Protozoon gefunden, 21,7% der Tiere waren mit Kokzidien infiziert (davon 78,3% Isospora spp., 13,0% Choleoeimeria spp., 6,5% Eimeria spp., 2,2% Mischinfektion Isospora spp./Choleoeimeria spp.) und 8,5% mit Flagellaten oder Ziliaten. Bei 83,3% der Tiere mit gastrointestinalen Symptomen konnte ein Befall mit Kokzidien der Gattung Isospora nachgewiesen werden. In 38,7% der koproskopischen Untersuchungen konnten Nematoden (65,9% Oxyuriden, 19,5% Askariden/ Heterakiden, 1,4% Rhabdias sp., 2,8% Strongyloides sp., je 0,5 % Spirurida, Heterakiden/Filarien, Oxyuriden/Strongyloiden) und in 2,8% Trematoden (Digenea) aufgefunden werden. Anamnestisch konnten in 35,8% aller Tiere klinische Symptome beobachtet werden, wovon bei 88,2% der erkrankten Tiere ein Endoparasitenbefall nachzuweisen war. Insgesamt 64,1% der sezierten Chamäleons waren mit Endoparasiten befallen, wovon 68,3% Mono- und 31,7% Mischinfektionen beherbergten. In 31,3% der sezierten Chamäleons wurden Nematoden gefunden und der Befall wurde in 55,0% dieser Fälle als hochgradig eingestuft. Es wurden Befallsraten von 25,0% für Strongyloides sp., 23,4% für Askariden/ Heterakiden,15,0% für Filarien, 5,0% für Rhabdias sp., 9,4% für Zestoden, 10,9% für Digenea registriert. In 11,3% der Fälle lagen Mischinfektionen vor. Damit ist ein Endoparasitenbefall bei Chamäleons häufig und kann zu Erkrankungen führen. Die Exposition unterscheidet sich bei Wildfängen und Nachzuchten aufgrund der unterschiedlichen Umgebungsbedingungen. Auch klinisch unauffällige Tiere waren zu 27,8% mit Parasiten befallen, so dass eine klinische Symptomatik nicht zwingend aus einem Parasitenbefall resultiert. Insgesamt betrachtet verdient der Endoparasitenbefall von Chamäleons das Augenmerk von Tierärzten und Tierhaltern und sollte bei augenscheinlich hohem Infektionsdruck zu Gegenmaßnahmen, insbesondere auch einer verbesserten Hygiene, Anlaß geben. / In the present study 212 chameleon fecal samples were examined for parasite stages and 75 carcasses were examined histopathologically and pathologically in a proven case of a parasite infestation. The basis of this study was to describe the occurrence and harmful effects of internal parasites considering the origin, age and sex of the chameleons. Of the 212 fecal samples 55.2% showed stages of endoparasites. Parasites were detected at 54.7% of 64 evaluated and dissected animals. The proportion of positive samples shows no significant difference between offspring (55.5%) and wild specimens (54.1%). In wild specimens common internal parasites could be determined with an indirect life cycle, however offspring harbored more parasites with a direct life cycle. In the studied chameleons coccidia as the genus Isospora and Oxyurids were regularly detected. In the coprological study Cestodes could not be found, while in the pathological examination they could be diagnosed sporadically in the intestine. Based on the total number of investigated chameleons the frequency of detection of parasite stages are presented as follows: Protozoa were found in 30.4%, 21.7% of the animals were infected with coccidia (of which 78,3% Isospora spp, 13,0% Choleoeimeria spp., 6.5% Eimeria spp., 2.2% polyinfections between Isospora spp./ Choleoeimeria spp.) and 8.5% with flagellates or ciliates. At 83.3% of the animals with gastrointestinal symptoms coccidia of the genus Isospora were detected. In 38.7% of the fecal examination nematodes were determined (65.9% Oxyurids, 19.5% Ascarids/ Heterakis, 1.4% Rhabdias sp., 2.8% Strongyloides sp., 0.5% Spirurida, Heterakids/ Filariae, Oxyurids/ Strongyloides sp.) and Trematodes in 2.8% (Digenea) were found. The anamnesis showed that clinical symptoms could be observed in 35.8% of all of the animals, whereas endoparasite infestation could be detected inn 88.2% of the affected animals. Overall, 64.1% of the dissected chameleons were infested with parasites, of which 68.3% harbored mono- and 31.7% polyinfections. In 31.3% of the dissected chameleons nematode infestations were found and 55.0% of these cases were classified as severe. Prevalences were registered: 25.0% for Strongyloides spp., 23.4% for Ascarids/ Heterakids, 15.0% for Filaria, 5.0% for Rhabdias sp., 9.4% for Cestodes, 10.9% for Digenea. In 11.3% of the cases mixed infections were reported. Thus, endoparasite infestation is common among chameleons and can lead to diseases. Exposure differs from wild-specimens and captive-bred due to the different environmental conditions. Also, 27.8% of clinically healthy animals were also infested with parasites, which means that clinical symptoms are not necessarily the result of a parasitic infestation. Overall, chameleon endoparasites deserve the attention of veterinarians and pet owners and should be treated promptly when there is a high likelihood of infection or hygiene is of concern.

This study investigates the etiology, diagnosis, and treatment of follicular stasis in female veiled chameleons (Chamaeleo calyptratus). Reproductive status was assessed by enzyme immunoassay of fecal metabolites of estrogen, progesterone, testosterone, and corticosterone; ultrasonography; and male introduction trials. Ultrasonography and hormone pattern analysis confirmed follicular stasis, while female response to male presence was inconclusive. Hormone patterns of corticosterone metabolites indicated a cyclical pattern consistent with reproductive events, but there was insufficient data to compare peak levels between ovulatory and non-ovulatory cycles. Ovulation induction was unsuccessful using either chicken GnRH-II, or a combination of progesterone and prostaglandin F2α. Feed restriction induced weight loss, but this was not directly related to changes in follicle size. Prevention of follicular development (i.e. contraception) was attempted using Depo-Provera and Lupron Depot, but neither treatment was effective. The outcomes of this study supplement the information on follicular stasis in reptiles, but further research is still needed. / NSERC, Toronto Zoo