Produção e composição química de seis leguminosas forrageiras no município de Altamira, Pará.

bitstream/item/33955/1/CPATU-CirTec41.pd

Extensive Investigations on Radial Crack Formation in Labyrinth Seals of Aircraft Engines

Labyrinth seals are due to their non-contact function and their thermal resistance the state of the art in sealing technology for thermal turbomachinery such as jet engines. The purpose of labyrinth seals is to adjust or minimize the leakage between rotor and stator. However, because of transient flight manoeuvres and the resulting mechanical and thermal loads on the components, contact between rotating and stationary parts cannot be ruled out. The aim of this study is to extend the basic understanding of the mechanisms of hot crack formation in the components of a labyrinth seal during the rubbing process. Previous investigations at the Institute of Thermal Turbomachinery have shown that the thermally induced stress caused in connection with the thermal change of the material properties can lead to formation of the cracks in the seal fin. In order to get a deeper understanding of the complex crack initiation mechanisms, it is necessary to carry out fundamental experiments on simplified geometries. For this purpose, the stress conditions of a loaded labyrinth seal are applied to a cylindrical test specimen. It is fixed on both sides and subjected to thermo-cyclic load. To model a rubbing process of a labyrinth seal, the initial temperature of the cycle corresponds to the operating temperature of the rotor in a jet engine and the final temperature corresponds to the contact temperature during the rubbing process. The temperature change causes stress in the specimen due to the rigid mounting. In literature there are analytical considerations regarding the stress-strain curve in the seal fin and a possible pre-damage of the components by remaining tensile stress after the rubbing process. In this paper, these analytical approaches are compared with the test data. Also a residual tensile strength of the seal fin which is still to be tolerated is worked out depending on the temperature load. The stress reduction during heating is very significant and is considered in detail. Due to the high mechanical and thermal loads, the stress reduction is superimposed by relaxation and plastic deformation. For a separate consideration of these basic effects, FE simulations are carried out. The main findings are that stress and strain in the component depends on both the initial and the final temperature of the specimen. The final rubbing temperature mainly influences the remaining tensile stress. With the thus calculated remaining strength of the seal fin a probable crack formation could be determined. The evaluation of this data contributes significantly to the understanding of hot crack formation in labyrinth seal fins and is therefore the basis for the optimization of the sealing system with regard to robustness against rubbing processes

Produção e composição química de cultivares de capim elefante no município de Altamira-PA.

bitstream/item/57537/1/Belem-BP1.pd

Behavioural and fitness effects of translocation to a novel environment: Whole‐lake experiments in two aquatic top predators

Translocation into a novel environment through common fisheries management practices, such as fish stocking, provides opportunities to study behavioural and fitness impacts of translocations at realistic ecological scales. The process of stocking, as well as the unfamiliarity with novel ecological conditions and the interactions with resident fish may affect translocated individuals, leading to alterations of behaviours and causing fitness impacts. Our objectives were to investigate how aquatic top predators behaviourally establish themselves and compete with resident individuals following introduction in a novel lake environment and to investigate the resulting fitness consequences. Using high‐resolution acoustic telemetry, we conducted whole‐lake experiments and compared the activity, activity‐space size and fate of translocated and resident individuals in two model top predators, the northern pike Esox lucius (n = 160) and European catfish Silurus glanis (n = 33). Additionally, we compared the reproductive success of translocated and resident northern pike. The experiment was conducted with large (adult) individuals of different origins, resilient to predation, but subject to agonistic interactions and competition with resident fish. Over a period of several months, the translocated catfish exhibited consistently larger activity‐space sizes than resident catfish, but did not differ from residents in activity and survival. The pike from one of the two translocated origins we tested also showed elevated space‐use, and both translocated origins revealed higher mortality rates than their resident conspecifics, indicating maladjustment to their novel environment. When non‐resident pike reproduced, they overwhelmingly produced hybrid offspring with resident fish, indicating that introductions fostered gene flow of non‐native genes. Our study indicates that fish introductions result in behavioural and fitness impacts even in large‐bodied top predators that experience low levels of natural predation risk.Leibniz CommunityBesatzfisch (German Federal Ministry for Education and Research)Peer Reviewe

Does location congruence matter? : A field study on the effects of location-based advertising on perceived ad intrusiveness, relevance & value

We investigate the effect of location-congruent mobile messages on perceived intrusiveness, value, and relevance through a field experiment using the Experience Sampling Method (ESM). We developed a mobile application for undergraduate students, featuring campus news and information concerning class schedules. This application also included daily ads for the University restaurant, which were either location-(semi)congruent or location-incongruent. Immediately after viewing the ads the app presented a short questionnaire to the participants for a period of four weeks, thereby measuring their perceived intrusiveness, relevance and value of these ads. During these four weeks daily ads were sent to 40 students, resulting in 107 responses from 23 participants. The results show that our participants perceived location-(semi)congruent ads as significantly more valuable and relevant, whereas no significant results were found for perceived intrusiveness. By investigating LBA in a field-study based on ESM utilizing participants’ own smartphone devices this study corroborates the presumed effects of location-(semi)congruency on marketing relevant ad perceptions.</p

The antimalarial drug amodiaquine stabilizes p53 through ribosome biogenesis stress, independently of its autophagy-inhibitory activity

Pharmacological inhibition of ribosome biogenesis is a promising avenue for cancer therapy. Herein, we report a novel activity of the FDA-approved antimalarial drug amodiaquine which inhibits rRNA transcription, a rate-limiting step for ribosome biogenesis, in a dose-dependent manner. Amodiaquine triggers degradation of the catalytic subunit of RNA polymerase I (Pol I), with ensuing RPL5/RPL11-dependent stabilization of p53. Pol I shutdown occurs in the absence of DNA damage and without the subsequent ATM-dependent inhibition of rRNA transcription. RNAseq analysis revealed mechanistic similarities of amodiaquine with BMH-21, the first-in-class Pol I inhibitor, and with chloroquine, the antimalarial analog of amodiaquine, with well-established autophagy-inhibitory activity. Interestingly, autophagy inhibition caused by amodiaquine is not involved in the inhibition of rRNA transcription, suggesting two independent anticancer mechanisms. In vitro, amodiaquine is more efficient than chloroquine in restraining the proliferation of human cell lines derived from colorectal carcinomas, a cancer type with predicted susceptibility to ribosome biogenesis stress. Taken together, our data reveal an unsuspected activity of a drug approved and used in the clinics for over 30 years, and provide rationale for repurposing amodiaquine in cancer therapy

Adapting Decision DAGs for Multipartite Ranking

European Conference, ECML PKDD 2010, Barcelona, Spain, September 20-24, 2010Multipartite ranking is a special kind of ranking for problems in which classes exhibit an order. Many applications require its use, for instance, granting loans in a bank, reviewing papers in a conference or just grading exercises in an education environment. Several methods have been proposed for this purpose. The simplest ones resort to regression schemes with a pre- and post-process of the classes, what makes them barely useful. Other alternatives make use of class order information or they perform a pairwise classi cation together with an aggregation function. In this paper we present and discuss two methods based on building a Decision Directed Acyclic Graph (DDAG). Their performance is evaluated over a set of ordinal benchmark data sets according to the C-Index measure. Both yield competitive results with regard to stateof- the-art methods, specially the one based on a probabilistic approach, called PR-DDA