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Search Results: 1 - 10 of 588 matches for " Dietmar Roessl "
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Trust between Boundary-Spanning Agents: The Role of Relational Competencies  [PDF]
Isabella Hatak, Dietmar Roessl
Open Journal of Social Sciences (JSS) , 2015, DOI: 10.4236/jss.2015.33001
Abstract:

Against the background of principal-agent and transaction-cost theoretical considerations, this study addresses the question whether relational competencies relate to trust within cooperative relationships, taking into account also situational and personal factors. In its conclusion, the study presents an experimentally confirmed model (n = 282) that shows the strong causal relationship between relational competencies and trust allowing boundary-spanning agents to exert influence on the development and maintenance of complex cooperative relationships characterized by long-term objectives.

Pion-Kaon Scattering near the Threshold in Chiral SU(2) Perturbation Theory
Arnold Roessl
Physics , 1999, DOI: 10.1016/S0550-3213(99)00336-3
Abstract: In the context of chiral SU(2) perturbation theory, pion-kaon scattering is analysed near the threshold to fourth chiral order. The scattering amplitude is calculated both in the relativistic framework and by using an approach similar to heavy baryon chiral perturbation theory. Both methods lead to equivalent results. We obtain relations between threshold parameters, valid to fourth chiral order, where all those combinations of low-energy constants which are not associated with chiral-symmetry breaking terms drop out. The remaining low-energy constants can be estimated using chiral SU(3) symmetry. Unfortunately, the experimental information is not precise enough to test our low-energy theorems.
Localizing gravity on a 't Hooft-Polyakov monopole in seven dimensions
Ewald Roessl,Mikhail Shaposhnikov
Physics , 2002, DOI: 10.1103/PhysRevD.66.084008
Abstract: We present regular solutions for a brane world scenario in the form of a 't Hooft-Polyakov monopole living in the three-dimensional spherical symmetric transverse space of a seven-dimensional spacetime. In contrast to the cases of a domain-wall in five dimensions and a string in six dimensions, there exist gravity-localizing solutions for both signs of the bulk cosmological constant. A detailed discussion of the parameter space that leads to localization of gravity is given. A point-like monopole limit is discussed.
Living Inside a Hedgehog: Higher-dimensional Solutions that Localize Gravity
Tony Gherghetta,Ewald Roessl,Mikhail Shaposhnikov
Physics , 2000, DOI: 10.1016/S0370-2693(00)00979-5
Abstract: We consider spherically symmetric higher-dimensional solutions of Einstein's equations with a bulk cosmological constant and n transverse dimensions. In contrast to the case of one or two extra dimensions we find no solutions that localize gravity when $n\geq 3$, for strictly local topological defects. We discuss global topological defects that lead to the localization of gravity and estimate the corrections to Newton's law. We show that the introduction of a bulk ``hedgehog'' magnetic field leads to a regular geometry and localizes gravity on the 3-brane with either a positive, zero or negative bulk cosmological constant. The corrections to Newton's law on the 3-brane are parametrically the same as for the case of one transverse dimension.
Combined Ang-2 and VEGF Targeting Therapies in Renal Cell Carcinoma  [PDF]
Nikolett Molnar, Dietmar W. Siemann
Journal of Cancer Therapy (JCT) , 2013, DOI: 10.4236/jct.2013.49A2001
Abstract:

Angiogenesis, the growth of new vessels from pre-existing ones, is an important feature of tumor growth that has been exploited as a therapeutic target in oncology. Given its key role in facilitating blood vessel sprouting, VEGF has been a major focus of anti-angiogenic strategies, but the observation of resistance in some clinical trials utilizing such agents has led to a search for new or complementary targets in angiogenesis process. The Angiopoietin/Tie2 pathway and in particular the Angiopoietin-2 (Ang-2) ligand which is critically involved in the destabilization of normal vasculature, has been identified as one such target. The current study investigated the potential benefits of combining an Ang-2 targeted therapy with small molecule VEGF targeted agents (Sunitinib, Cediranib) in a human renal cell carcinoma model. The results showed that while both Ang-2 and VEGF interference on their own impaired tumor growth and new blood vessel formation, the combination of agents that targeted both pathways resulted in significantly superior anti-tumor and anti-angiogenic effects.

Quantum Measurements Generating Structures of Numerical Events  [PDF]
Dietmar Dorninger, Helmut L?nger
Journal of Applied Mathematics and Physics (JAMP) , 2018, DOI: 10.4236/jamp.2018.65085
Abstract: Let S be a set of states of a physical system and p(s) the probability of an occurrence of an event when the system is in state s∈S. The function p from S to [0,1] is called a numerical event, multidimensional probability or, more precisely, S-probability. If a set of numerical events is ordered by the order of real functions one obtains a partial ordered set P in which the sum and difference of S-probabilities are related to their order within P. According to the structure that arises, this further opens up the opportunity to decide whether one deals with a quantum mechanical situation or a classical one. In this paper we focus on the situation that P is generated by a given set of measurements, i.e. S-probabilities, without assuming that these S-probabilities can be complemented by further measurements or are embeddable into Boolean algebras, assumptions that were made in most of the preceding papers. In particular, we study the generation by S-probabilities that can only assume the values 0 and 1, thus dealing with so called concrete logics. We characterize these logics under several suppositions that might occur with measurements and generalize our findings to arbitrary S-probabilities, this way providing a possibility to distinguish between potential classical and quantum situations and the fact that an obtained structure might not be sufficient for an appropriate decision. Moreover, we provide some explanatory examples from physics.
The development of drugs for treatment of sleeping sickness: a historical review
Dietmar Steverding
Parasites & Vectors , 2010, DOI: 10.1186/1756-3305-3-15
Abstract: Human African trypanosomiasis or sleeping sickness is a disease caused by two subspecies of Trypanosoma brucei, T. b. rhodesiense and T. b. gambiense. The parasites live and multiply extracellularly in blood and tissue fluids of their human host and are transmitted by the bite of infected tsetse flies (Glossina spp.). The occurrence of sleeping sickness is restricted to the distribution of tsetse flies which are exclusively found in sub-Saharan Africa between 14°N and 20°S [1]. More than 250 discrete active sleeping sickness foci in 36 African countries are recognised most of which are in rural areas [2].Trypanosoma b. rhodesiense is found in East and southern Africa whereas T. b. gambiense occurs in West and Central Africa. The course of sleeping sickness is different depending on the subspecies. Infections with T. b. rhodesiense lead to an acute form of the disease while infections with T. b. gambiense give rise to a chronic infection. The symptoms of the first stage of the disease, defined by the restriction of trypanosomes to the blood and lymph system, include fever, headache, joint pain and itching [3,4]. The clinical signs of the second stage of the disease, characterised by the invasion of trypanosomes into the central nervous system, are neurological and endocrinal disorders [3,4]. If left untreated, sleeping sickness patients infected with T. b. rhodesiense will die within months whereas those infected with T. b. gambiense usually survive for several years.In the late 19th Century, Africa experienced several sleeping sickness epidemics the most devastating of which was an epidemic with 300,000 to 500,000 deaths between 1896 and 1906 which mainly affected the Congo Basin and the Busoga focus in Uganda and Kenya [5]. The disastrous effect of this epidemic persuaded the various colonial administrations to call for their medical scientists to develop a cure for sleeping sickness. At that time, the field of chemotherapy was developing and had begun to make use
The history of African trypanosomiasis
Dietmar Steverding
Parasites & Vectors , 2008, DOI: 10.1186/1756-3305-1-3
Abstract: African trypanosomiasis is an infectious disease of humans and animals of similar aetiology and epidemiology. The causative agents of the disease are protozoan parasites of the genus Trypanosoma that live and multiply extracellularly in blood and tissue fluids of their mammalian hosts and are transmitted by the bite of infected tsetse flies (Glossina sp.). The distribution of trypanosomaisis in Africa corresponds to the range of tsetse flies and comprises currently an area of 8 million km2 between 14 degrees North and 20 degrees South latitude [1]. Throughout history, African trypanosomiasis has severely repressed the economic and cultural development of Central Africa.African animal trypanosomiasis or nagana disease is caused by T. congolense, T. vivax and T. brucei spp. In wild animals, these parasites cause relatively mild infections while in domestic animals they cause a severe, often fatal disease. All domestic animals can be affected by nagana and the symptoms are fever, listlessness, emaciation, hair loss, discharge from the eyes, oedema, anaemia, and paralysis. As the illness progresses the animals weaken more and more and eventually become unfit for work, hence the name of the disease "N'gana" which is a Zulu word that means "powerless/useless" [2]. Because of nagana, stock farming is very difficult within the tsetse belt.Human African trypanosomiasis or sleeping sickness is caused by two subspecies of T. brucei, T. brucei gambiense and T. brucei rhodesiense, while the third subspecies, T. brucei brucei, is only infectious to animals. T. b. gambiense is responsible for the chronic form of sleeping sickness in West and Central Africa, whereas T. b. rhodesiense gives rise to the acute form of the disease in East and Southern Africa. There are two distinct stages during the course of sleeping sickness. The first or early stage of the disease, also known as the haemolymphatic phase, is defined by the restriction of the trypanosomes to the blood and lymph system
From birdsong to speech: a plea for comparative approaches
Todt, Dietmar;
Anais da Academia Brasileira de Ciências , 2004, DOI: 10.1590/S0001-37652004000200003
Abstract: human language and speech are unique accomplishments. nevertheless, they share a number of characteristics with other systems of communication, and investigators have thus compared them to birdsong and the vocal signaling of nonhuman primates. particular interesting parallels concern the development of singing and speaking. these behaviors rely on auditory perception, subsequent memorization and finally, the generation of vocal imitations. several mechanisms help young individuals to deal with the various challenges during the time of signal development. specific differences aside, astounding parallels can be found also in how a human and a particularly accomplished bird like the common nightingale luscinia megarhynchos treat the experience of many different sound patterns or songs. as a consequence of such exposure, both human infants and young birds eventually acquire large repertoires of verbal or vocal signals. these achievements, however, require access to specific memory mechanisms which are well adapted to the purposes they serve, thereby allowing them to fulfil their species typical roles. with such aspects as a reference, birdsong is an excellent biological model for memory research and also an appropriate system for the study of evolutionary strategies in a very successful class of organisms.
Polysemy, polyvalence, and linking mismatches: the concept of RAIN and its codings in English, German, Italian, and Spanish
Zaefferer, Dietmar;
DELTA: Documenta??o de Estudos em Lingüística Teórica e Aplicada , 2002, DOI: 10.1590/S0102-44502002000300004
Abstract: based on an ontological frame for comparative onomasiological lexicology which embeds the rain eventity type as an exponent-shaped activity into a general linguistic ontology as well as an ontology of motion, the words for rain in two germanic and two romance languages are compared with respect to their semantic and syntactic variability. it turns out that the germanic forms are more flexible than the romance forms. english rain has the highest variability: it can be used with eight valencies, a nominal and seven verbal ones, and with five different meanings, and it is the only one to display a valence that combines an expletive subject with a cognate object as well as a causativized eventity meaning. on the other hand only german regnen has a resultativized meaning. the romance languages too show some internal variance: in allowing both an impersonal construction with a generalized meaning and a source construction, spanish llover is slightly more flexible than italian piovere. finally, an optimality theoretic account of the data is adumbrated in terms of three principles: avoid linking mismatches, avoid heterogeneity of sentence patterns, and avoid redundancy.
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