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Search Results: 1 - 10 of 224764 matches for " R. Fritz "
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La ley del crecimiento del entrehierro en máquinas eléctricas
Maudanz Horst Fritz R.
Ingeniería e Investigación , 1984,
Abstract: Según el profesor Strnad (Alemania), en los dise os deben utilizarse modernos métodos integrados que contienen los criterios clásicos, pero enriquecidos por la consideración de una calidad predeterminada, una seguridad exigida, un riesgo calculado, una optimización, no parcial sino total, incluyendo no solamente las funciones sino también los procesos.
Ecoeficiencia: el "leitmotiv" del desarrollo
Fritz R?uchle,Richard Korswagen
Revista Economía , 2000,
Abstract: El artículo no presenta resumen.
NN Correlations and Relativistic Hartree Fock in Finite Nuclei
R. Fritz,H. Müther
Physics , 1993, DOI: 10.1103/PhysRevC.49.633
Abstract: Two different approximation schemes for the self-consistent solution of the relativistic Brueckner-Hartree-Fock equation for finite nuclei are discussed using realistic One-Boson-Exchange potentials. In a first scheme, the effects of correlations are deduced from a study of nuclear matter and parameterized in terms of an effective $\sigma$, $\omega$ and $\pi$ exchange. Employing this effective interaction relativistic Hartree-Fock equations are solved for finite nuclei \osi , \caf\ and \cafe . In the second approach the effect of correlations are treated in the Brueckner-Hartree-Fock approximation directly for the finite nuclei, but the modifications of the Dirac spinors in the medium are derived from nuclear matter assuming a local-density approximation. Both approaches yield rather similar results for binding energies and radii in fair agreement with experimental data. The importance of the density dependent correlation effects is demonstrated and different ingredients to the spin-orbit splitting in the shell-model of the nucleus are discussed.
Dirac Hartree-Fock for Finite Nuclei Employing realistic Forces
R. Fritz H. Müther,R. Machleidt
Physics , 1993, DOI: 10.1103/PhysRevLett.71.46
Abstract: We discuss two different approximation schemes for the self-consistent solution of the {\it relativistic} Brueckner-Hartree-Fock equation for finite nuclei. In the first scheme, the Dirac effects are deduced from corresponding nuclear matter calculations, whereas in the second approach the local-density approximation is used to account for the effects of correlations. The results obtained by the two methods are very similar. Employing a realistic one-boson-exchange potential (Bonn~A), the predictions for energies and radii of $^{16}$O and $^{40}$Ca come out in substantially better agreement with experiment as compared to non-relativistic approaches. As a by-product of our study, it turns out that the Fock exchange-terms, ignored in a previous investigation, are not negligible.
Climate Change Favors Grapevine Production in Temperate Zones  [PDF]
Bruno Koch, Fritz Oehl
Agricultural Sciences (AS) , 2018, DOI: 10.4236/as.2018.93019
Abstract: Wine production has a long-standing history in Palatinate (Southwestern Germany), dating back to Roman times. Especially “Riesling”, but also several “Pinot” varieties gained major significance. Red wine varieties gained prominence over the last 20 years only, which may be a consequence of climate change. Our objective was to review temperature and rainfall data over the last 40 years, measured “on-winery” in Hainfeld and correlate these data with grapevine growth parameters: the development of bud break, flowering, veraison and harvest dates, yields and grape sugar concentrations of “Pinot Gris”, “Pinot Noir”, “Riesling”, “Silvaner” and “Müller-Thurgau”. Since the 1970s, bud break, flowering and veraison are 11 - 15, 18 - 22 and 16 - 22 days earlier; harvest dates are 25 - 40 days earlier. Sugar concentrations increased significantly, but yields decreased. Annual rainfall has not significantly risen, while the mean annual minimum and maximum air-temperatures rose by ~0.9°C, and by ~3.4°C, respectively, resulting in an average increase of the mean annual temperature of ~2.1°C. Remarkably, both mean monthly minimum and maximum temperatures rose especially in springtime, which should have been the driver for earlier bud break and flowering. A change in the climatic conditions, therefore, appears to be one of the key reasons for more favorable grapevine production in Palatinate, especially for “Pinot Noir”, which showed the highest increase in sugar concentrations. The Huglin-index, a measure for the suitability of growing specific grapevine varieties in given environments, increased from 1685 to 2063. According to this index, the climate change may be favorable already for growing grape varieties so far rarely grown in temperate zones, such as “Cabernet Sauvignon”, “Syrah” and “Tempranillo” that are more suited to warmer, Mediterranean climates.
The human sirtuin family: Evolutionary divergences and functions
Athanassios Vassilopoulos, Kristofer S Fritz, Dennis R Petersen, David Gius
Human Genomics , 2011, DOI: 10.1186/1479-7364-5-5-485
Abstract: Epigenetic modifications of protein, histone and chromatin play an important role in regulating gene expression, cancer formation and life span. Acetylation is a major player in epigenetic modifications, resulting in open chromatin structures and, hence, permissive conditions for transcription-factor recruitment to the promoters, followed by initiation of transcription. By contrast, histone deacetylases (HDACs) oppose the activity of histone acetyltransferases by removing the acetyl groups from lysine residues within specific promoters, leading to gene silencing [1]. In addition, many non-histone proteins have been identified as substrates of HDACs, implicating acetylation as a post-translational modification that affects various aspects of cell physiology [2]. There are two protein families having HDAC activity: the classical HDAC family, which consists of two different phylogenetic classes (class I and class II); and the sirtuin family of proteins, which requires the co-factor nicotinamide adenine dinucleotide (NAD) for its deacetylase activity [3,4].The sirtuin family of proteins is highly conserved, both functionally and structurally. Its members are integrated into most forms of life, including eubacteria, archaea and eukaryotes, and therefore predate both histone and chromatin formation [5]. Sirtuins have been involved in metabolic and chromatin regulation throughout evolution, dating back to the first examples of chromatin-like organisation of DNA in archaea [6,7]. The silent information regulator 2 gene (Sir2) was first discovered in Saccharomyces cerevisiae and was named after its ability to relieve gene silencing [8]. Once discovered, sirtuins were rapidly characterised in yeast, bacteria, plants and mammals.Sirtuins belong to the deoxyhypusine synthase (DHS)-like NAD/flavin adenine dinucleotide (FAD)-binding domain clan and all members contain the Rossmann fold structural motif, which can be found in proteins that bind nucleotides. The other members of th
Actividad antimicrobiana de mieles del sudeste de la provincia de Buenos Aires frente a Escherichia coli
Fangio,M.F.; Iurlina,M.O.; Fritz,R.;
Revista argentina de microbiolog?-a , 2007,
Abstract: this study assessed the susceptibility of escherichia coli to the antimicrobial activity of honeys by different techniques. honeys used were from the southeast region of buenos aires province. in order to evaluate antimicrobial activity against escherichia coli atcc 25922, solutions containing 0, 1, 5, 10, 25 and 50% (w/v) of honey were prepared. liquid media (mueller-hinton and mac conkey broths) were used to assess the minimal inhibitory concentration (mic) by the serial dilution test. the minimal bactericidal concentration (mbc) was determined by counting on nutritive and mac conkey agar. in addition, for the evaluation of total antibacterial activity, the agar diffusion method was used. a reduction of microbial growth of 96% in mueller-hinton broth and of 90% in mac conkey broth by honey solutions containing 50% and 25% (w/v), was respectively observed. the bactericide action of honey in nutritive agar proved negative. the mbc value in mac conkey agar was 25% (w/v) of honey. the methods used for measuring the antibacterial activity in the present work were adequate to prove that honeys are active against e. coli at 25 and 50% (w/v) concentrations. the results obtained by the dilution method with mueller- hinton broth and the agar diffusion method were both concordant.
Evaluation of culture media for Paenibacillus larvae applied to studies of antimicrobial activity
Gende,L. B.; Eguaras,M. J.; Fritz,R.;
Revista argentina de microbiolog?-a , 2008,
Abstract: this study was conducted to compare different liquid culture media for paenibacillus larvae growth in order to find the best one to be used in studies on activity of antimicrobial substances, such as essential oils. p. larvae presented poor growth in usual broths such as mueller-hinton, commonly employed in antimicrobial activity assays. growth in liquid media was evaluated using paenibacillus larvae strains isolated from hives located in different geographical zones. the myt medium (mueller-hinton broth, yeast extract and thiamine) was selected out of the eight liquid media analyzed, as it proved to be the most adequate due to its higher absorbance at 620 nm. the following mean values were obtained from the four p. larvae strains: 0.227 ± 0.016 for the cobo strain, 0.279 ± 0.015 for la plata strain, 0.758 ± 0.020 for mechongué strain and 0.244 ± 0.0079 for sierra de los padres strain, respectively.
Intubación nasotraqueal guiada por fibrosocopio retromolar de Bonfils por vía oral
Gempeler R,Fritz E; Díaz B,Y. Lorena;
Revista Colombiana de Anestesiología , 2011, DOI: 10.5554/rca.v39i1.81
Abstract: introduction. among the various devices available for airway management, one of them stands out: the retromolar bonfils fiberscope. the bonfils has proven to be effective and easy to use, besides being non-traumatic and useful in patients in whom direct laryngoscopy is unsuccessful, in patients with cervical trauma, limitation of mouth opening and intubation with the patient awake. methodology. this case report describes the oral bonfils-guided nasotracheal intubation technique, successfully accomplished in 19 patients. conclusions. the experience obtained with this device in over 300 oral intubations leads us to believe that the bonfils retromolar fiberscope is ideal and superior to the conventional laryngoscope for the routine management of the airway.
Community - based management in two biosphere reserves in Madagascar – distinctions and similarities: What can be learned from different approaches ?
NVM Fritz - Vietta, C R ttger, S Stoll - Kleemann
Madagascar Conservation & Development , 2009,
Abstract: This article explores the socio - cultural aspects of community - based management of natural resources in Madagascar. The contractual devolution of management rights and responsibilities to local user groups constitutes an important instrument in the country’s environmental policy. Its challenges and opportunities are investigated through a case study that scrutinizes two biosphere reserves: Mananara - Nord at the northeast, and Sahamalaza at the northwest coast of Madagascar. While Mananara is relatively well established, having successfully realized more than twenty management transfers, implementation in Sahamalaza is still in its infancy. Comparing both sites allows for drawing a picture of major factors that influence the success of this instrument. Data was gathered using a qualitative social research approach based on interviews and participatory rural appraisal. A conceptual framework integrating informal institutions and the concept of social capital was used to better understand socio - cultural dynamics within rural communities. The paper presents the characteristics of both sites and explores traditional natural resource use, local associations, and their role in collective action, as well as customary institutional arrangements. The results provide insight into strengthening local management capacities and cooperation. They also highlight the need to leverage local knowledge and to reconcile the different formal and informal rules for active and responsible involvement of concerned community members in sustainable resource management.
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