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Search Results: 1 - 10 of 1018 matches for " Estela; Litz "
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Morfogénesis in vitro de dioon merolae de Luca, Sabato & Vázquez-Torres (zamiaceae, cycadales) a partir de megagametofitos y embriones cigóticos
Cabrera Hilerio,Sandra Luz; Chávez ávila,Victor Manuel; Sandoval Zapotitla,Estela; Litz,Richard E; Cruz Sosa,Francisco;
Interciencia , 2008,
Abstract: organogenic cultures were induced from zygotic embryo and megagametophyte explants of the chiapas state (méxico) endangered cycad species, dioon merolae. the litz induction medium consisted of b5 major salts, ms medium minor salts and the organics glutamine (400mg·l-1), arginine (100mg·l-1), asparagines (100mg·l-1), sucrose (60g·l-1), gellan gum (4g), and supplemented with 0, 0.45, 2.26, 4.52 and 9.05μm 2,4-dichlorophenoxyacetic acid (2,4-d) and 0, 2.32, 4.60, 9.30, 13.90μm kinetin (k), arranged as a 5′5 factorial in a randomized block design. cultures were maintained in darkness at 25°c, and callus was subcultured onto fresh medium at 4 week intervals. callus initiation occurred on a wide range of plant growth regulators (pgr) combinations from megagametophyte explants. in comparison, callus initiation from explanted zygotic embryos occurred on few pgr combinations. adventitious shoot induction occurred from callus on formulations with k and 2,4-d. through the histological analysis of longitudinal sections of zygotic embryos were detected apical meristematic cells of the shoot and root and in megagametophytes the formation of elements similar to tracheids and coralloid roots. this technique has a great potential for preservation of the highly endangered cycads.
Globalization and the changing face of educational leadership: Current trends & emerging dilemmas
David Litz
International Education Studies , 2011, DOI: 10.5539/ies.v4n3p47
Abstract: This paper has used a deconstructivist conceptual framework in order to explore and analyze the multifaceted and complex impacts of globalization on educational leadership in the early 21st century. It will be argued that globalization has had far-reaching positive and negative effects on all of the various nation-states, cultures, economies, and peoples of the world and that these have also resulted in the emergence and evolution of a variety of interesting and practical educational leadership paradigms and managerial practices. In addition, this paper will conclude with several recommendations that can be used to guide additional research on the varied aspects and trends of educational leadership in a globalized context, and the development of international or cross-cultural international leadership development initiatives.
Aqueous Ti(IV)-Catalyzed Diels-Alder Reaction
Kyle E. Litz
Molecules , 2007, DOI: 10.3390/12081674
Abstract: The aqueous Diels-Alder reaction of 1,3-cyclohexadiene with 1,4-benzoquinone was compared and contrasted to the same reaction catalyzed with Flextyl P?, a novel Ti(IV) performance catalyst. The catalyst improved conversion by 22% versus the uncatalyzed reaction and represents a rare example of a Ti(IV) catalyzed Diels-Alder reaction in water.
Hyphessobrycon melanopleurus uruguayensis Messner, 1962, an available name and a senior synonym of Cyanocharax macropinna Malabarba & Weitzman, 2003 (Ostariophysi: Characidae)
Malabarba, Luiz R.;Weitzman, Stanley H.;Litz, Thomas;
Neotropical Ichthyology , 2004, DOI: 10.1590/S1679-62252004000200007
Abstract: hyphessobrycon melanopleurus uruguayensis, astyanacinus platensis, and astyanax stenohalinus, published in a mimeographed paper by messner in 1962 are considered available names. the subspecific name h. melanopleurus uruguayensis is recognized as a senior synonym of cyanocharax macropinna malabarba & weitzman, 2003, and therefore referred to as cyanocharax uruguayensis (messner, 1962), new combination.
Experimental f-value and isotopic structure for the Ni I line blended with [OI] at 6300A
S. Johansson,U. Litzén,H. Lundberg,Z. Zhang
Physics , 2003, DOI: 10.1086/374037
Abstract: We have measured the oscillator strength of the Ni I line at 6300.34 \AA, which is known to be blended with the forbidden [O I] $\lambda$6300 line, used for determination of the oxygen abundance in cool stars. We give also wavelengths of the two isotopic line components of $^{58}$Ni and $^{60}$Ni derived from the asymmetric laboratory line profile. These two line components of Ni I have to be considered when calculating a line profile of the 6300 \AA\ feature observed in stellar and solar spectra. We also discuss the labelling of the energy levels involved in the Ni I line, as level mixing makes the theoretical predictions uncertain.
Ichneumonoideos (Hymenoptera) parasitoides del complejo de orugas cortadoras en pasturas de alfalfa (Medicago sativa L.) en la Argentina Central
Estela, Baudino;
Neotropical Entomology , 2005, DOI: 10.1590/S1519-566X2005000300008
Abstract: the knowledge about the role of natural enemies is crucial for integrated pest management systems. parasitoids are considered most important for biological control, although the quantitative dimension of their effect on hosts is not always known. the objective of the present study was to survey the parasitoids of cutworms in the northeastern area of la pampa province, argentina. the field work was conducted during four years (1999 to 2002). larvae of agrotis gypaetina guenée, a. malefida (guenée) and peridroma saucia (hübner) (lepidoptera: noctuidae) were collected in a fortnightly interval in alfalfa pastures, in order to establish the incidence of hymenopterous parasitoids in three areas of the eastern physiographic area of la pampa, argentina. these larvae were kept in breeding laboratory and fed with artificial diet until emergence of the parasitoids. the larvae were then identified and quantified. parasitoid species of four genera of ichneumonidae were found: alophophion sp. cushman (ophioninae), campoletis sp. f?rster (campopleginae), thymebatis spp. brèthes (two species) and eutanyacra sp. cameron (ichneumoninae); and one species of braconidae: glyptapanteles bourquini (blanchard) (microgastrinae). new host species for alophophion, thymebatis and eutanyacra were recorded. alophophion was responsible for 80% of the parasitoidism, was present in all the regions studied and parasitized all the species of cutworm found.
El acceso temático en las Bibliotecas Públicas de la Ciudad de Buenos Aires
Informaci?3n, cultura y sociedad , 2004,
Abstract: the article presents the results of a field work carried out in 2003 to verify the tools of subject retrieval offered by public libraries in the city of buenos aires. it describes the vocabulary and the classification system used and also the possibilities of subject access by open stacks with a physical arrangement of the collection by subject, and online public access catalogs. it concludes with some recommendations to improve the efficiency of subject searching in public libraries.
Social y culturalmente ambiguos: criollos-mestizos de Tucumán, siglo XVII
Memoria americana , 2010,
Abstract: this article analyzes the influence of indigenous societies on the descendants of spanish conquistadors, known as criollos. the subject is approached through a case study which shows how a faction of san miguel de tucumán town council (cabildo) tried to prevent the admission of juan jordán de trejo as deputy governor (teniente de gobernador). he belonged to the melián de leguizamo y guevara family, owners of encomiendas in tafí, but his lower lineage made him served as the town's administrator. specific characteristics of his intercultural persona resembling a mirror image -referred to as spanishization or westernization of the indians- will be studied, including his fluency in the indigenous language, his knowledge of pre-hispanic societies and their territories and his illiteracy. his role as interethnic mediator (passeur culturel), and the advantages and drawbacks such a profile presents at different junctures, for social and political participation in the dominant group, will also be analyzed.
Inscribir el pasado en el presente: memoria y espacio urbano
Schindel, Estela;
Política y cultura , 2009,
Abstract: this work deals with the "memory places" as a privileged space of construction of collective memories in latin american societies affected by dictatorships or inner armed conflicts. this is exposed through three different types of memory places: "testimonial sites"; monuments, museums and memorials; and local, decentralized, performative practices of inscribing the memories in the public space. these are analyzed regarding issues such as the actors, addressees, contents and means involved in each case. in the context of what some authors call the "globalization of memory" the question about the existence of a specific latinamerican language of memory is posed.
?Por qué auditar a los comités de ética en investigación?
Revista Peruana de Medicina Experimental y Salud Pública , 2010, DOI: 10.1590/S1726-46342010000300019
Abstract: ethics committees in biomedical research have the responsibility to ensure the protection of human participants in the studies. in order to improve the quality of their work they must undergo audit procedures commissioned by the sponsors and inspections done by the regulatory authorities. through these procedures, improvement of their functions should be guaranteed, so they can optimize their tasks and accomplish in the best way the purpose for which they were created.
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