Growth of a mat-forming photograph in the presence of UV radiation

Knowledge of the survival and growth of microorganisms in the presence of ultraviolet radiation is important for understanding the potential for life to exist in environments exposed to high fluxes of UV radiation. The growth of a mat-forming phototrophic prokaryote, Chloroflexus aurantiacus, was examined in the presence of continuous high UV irradiation under otherwise optimal growth conditions. Evidence was sought for an intrinsic ability to grow in the presence of UV radiation in a carefully chosen organism known to be unusually resistant to UV radiation, of ancient lineage among the phototrophs, to resemble ancient microfossils from the Precambrian, and to be a mat-former. It was assumed that even a high intrinsic UV resistance would be inadequate for survival and growth in the presence of very high UV fluxes, and iron (Fe3+) was selected as a common, abundant UV-absorbing substance that might protest microorganisms growing in or under iron-bearing sediments. The effectiveness of Fe(3+) was tested as a UV protective agent at low concentrations in thin layers. It was concluded that intrinsic UV resistance in some organisms may account for growth, not just survival, of these organisms when exposed to high UV fluxes under otherwise optimal growth conditions in an anoxic environment. It was also concluded that Fe(3+) bearing sediments of 1 mm or less in thickness may provide an adequate shield against high UV fluxes permitting the growth of microorganisms just below their surface. As long as growth conditions were met, then the evolution and development of microorganisms would not be hampered by high UV fluxes impinging upon the surface of iron-bearing sediments

Variations in Texas school quality

Texas ; Education ; Federal Reserve District, 11th

Observations on the Interrelationships among Ants, Aphids, and Aphid Predators

Excerpt: The literature concerning the interactions of these insect groups is as interesting as it is extensive. It has generally been accepted that the relationship between ants and aphids has been one of mutualism in which ants derive all or a large part of their nutrients from aphid honeydew and perform special functions in return, primarily that of protecting aphids from their enemies. Every aspect of these associations has been covered by the excellent reviews of Nixon (1951) and Way (1963). It now appears that the nature and effectiveness of the protective value afforded the attended aphids by ants cannot be reduced to a simple statement of symbiosis. Nixon (1951) pointed out numerous situations that are responsible for fluctuations in the ant-aphid relationship. The emphasis in the present study was on the protection extended to Aphis rumicis Linn., a small aphid found on spirea shoots by the common tending ants. This restriction allowed constant surveillance of the protection supplied to a single aphid species by ants against the seasonal succession of predators. Aphid parasites were ignored in this study

The uneven distribution of health insurance

Insurance, Health

El Gran Viraje Hacia Afuera (The Great Outward Turn): Nascent Neo-Structuralism in Venezuela ; Balancing State and Market

This thesis uses Venezuela as a case study to test the potential viability of the neo-structural perspective of economic development. The theoretical perspectives of structuralism, neo-liberalism and neo‐ structuralism are discussed and critiqued in their ability to provide for economic development. Analysis is made of the change of the Venezuelan model of development from an inward-oriented to an outward-oriented model. Venezuelan development is traced from the adoption to the eventual demise of the inward-oriented model. The evolution toward outward-orientation is discussed within the context of the global, regional and national forces that contributed to the demise of the inward-oriented model and debt crisis. The implementation of the neo-liberal/IMF adjustment model in February of 1989 is outlined and consideration is given to the early results of the adjustment program. As a result of domestic resistance to neo-liberal principles and the state\u27s continued intervention and identification of structural goals, the emerging Venezuelan model is identified as neo-structural. The Venezuelan model is a synthesis of neo-liberal methods and structural perspectives. It is outward-oriented and its policies are based on the traditional IMF model, yet it identifies structuralist goals for its development program. The viability of the Venezuelan neo-structural model is evaluated in terms of its ability to fulfill its defined goals of: 1) sustained economic growth; 2) growth with equity; and 3) national self‐determination. Conclusions drawn from the Venezuelan case study indicate that the viability of the neo-structural model depends on finding the optimal balance of the state and market. The outlook for Venezuelan development under the neo-structural model is pessimistic, suggesting that neo-liberal market forces dominate the state’s ability to intervene to achieve structuralist goals. Conclusions, drawn from the Venezuelan case study, are discussed in light of their indications of the ability of a developing nation, through a neo-structural model, to set its own economic, social, and national priorities. General conclusions indicate that the global market increasingly dominates the developing nation-state\u27s ability to achieve nationally defined goals

Morphosyntactic cues to verb comprehension for typically developing toddlers and children with specific language impairment

Function morphemes assist typically developing (TD) children in segmenting speech, identifying syntactic categories, and mapping meaning onto words, yet function morphemes pose particular difficulty for children with specific language impairment(SLI). This investigation examined the effect of morphosyntactic context on verb comprehension for two groups of telegraphic speakers at the same expressive language stage as measured by mean length of utterance (MLU). The following two research questions were posed. Do young telegraphic speakers show increased verb comprehension given sentences containing a grammatical morpheme compared with sentences containing an im grammatical morpheme, a nonsense syllable, or no morpheme?Do children with SLI differ in verb comprehension for sentences with varying morphosyntactic contexts when compared with younger, MLU-matched TD children?Two MLU-equivalent groups participated, 16 TD children (age = 26 mos.) and 16 children with SLI (age = 48 mos.). Similar to Gerken and McIntosh (1993), a picture selection task was used to test verb comprehension in 4 contexts: grammatical auxiliary(Who is pushing?); omitted auxiliary (Who Φ pushing?); ungrammatical morpheme(Who in pushing?); and nonsense syllable (Who id pushing?). Auditory stimuli were digitally edited to control duration and naturalness.Experimental manipulation of “is” did not result in significant differences across morpheme contexts for either group. Verb comprehension probably was supported by verb lengthening associated with utterance-final position. Verbs also were marked by morpheme -ing. This morphosyntactic cue (i.e., morpheme -ing) may have aided verb comprehension regardless of auxiliary “is” variation. Findings suggest function morphemes are only one among many input cues available to language learners during comprehension, including prosodic, phonological, and contextual cues.Children with SLI had significantly higher verb comprehension than ID childrenacross morpheme contexts. Group differences favoring children with SLI(e.g., chronological age and receptive language) may explain this finding. Despitemorpheme anomalies, children with SLI demonstrated verb comprehension when the input cues were redundant and correlated with meaning. Discrepancies between these results and report of a grammaticality effect by McNamara, Carter, McIntosh, and Gerken(1998) are relevant to theories of SLI regarding limited processing capacity and memory limitations

Goya and the International Art Movements of his Time

A thesis presented to the faculty of the College of Arts and Sciences at Morehead State University in partial fulfillment of the requirements for the Degree of Master of Arts in Art by Beverly L. McNutt on April 22, 1991

The Texas Economy: Financing Availability

The Texas Economy: Financing AvailabilityBureau of Business Researc