Miami University

About: Miami University is a education organization based out in Oxford, Ohio, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 9949 authors who have published 19598 publications receiving 568410 citations. The organization is also known as: Miami of Ohio & Miami-Ohio.

Alkaline anaerobic respiration: isolation and characterization of a novel alkaliphilic and metal-reducing bacterium.

Abstract: Iron-reducing enrichments were obtained from leachate ponds at the U.S. Borax Company in Boron, Calif. Based on partial small-subunit (SSU) rRNA gene sequences (approximately 500 nucleotides), six isolates shared 98.9% nucleotide identity. As a representative, the isolate QYMF was selected for further analysis. QYMF could be grown with Fe(III)-citrate, Fe(III)-EDTA, Co(III)-EDTA, or Cr(VI) as electron acceptors, and yeast extract and lactate could serve as electron donors. Growth during iron reduction occurred over the pH range of 7.5 to 11.0 (optimum, pH 9.5), a sodium chloride range of 0 to 80 g/liter (optimum, 20 g/liter), and a temperature range of 4 to 45 degrees C (optimum, approximately 35 degrees C), and iron precipitates were formed. QYMF was a strict anaerobe that could be grown in the presence of borax, and the cells were straight rods that produced endospores. Sodium chloride and yeast extract stimulated growth. Phylogenetic analysis of the SSU rRNA gene indicated that the bacterium was a low-G+C gram-positive microorganism and had 96 and 92% nucleotide identity with Alkaliphilus transvaalensis and Alkaliphilus crotonatoxidans, respectively. The major phospholipid fatty acids were 14:1, 16:1omega7c, and 16:0, which were different from those of other alkaliphiles but similar to those of reported iron-reducing bacteria. The results demonstrated that the isolate might represent a novel metal-reducing alkaliphilic species. The name Alkaliphilus metalliredigens sp. nov. is proposed. The isolation and activity of metal-reducing bacteria from borax-contaminated leachate ponds suggest that bioremediation of metal-contaminated alkaline environments may be feasible and have implications for alkaline anaerobic respiration.

Subnatural linewidth averaging for coupled atomic and cavity-mode oscillators

Abstract: We calculate the spontaneous-emission spectrum and the spectrum of weakly driven fluorescence for a two-level atom coupled to a resonant-cavity mode. For strong atom-cavity coupling the spectra split into two peaks that can have subnatural linewidths. If the cavity linewidth is negligible, the spontaneous-emission spectrum has half the radiative linewidth of the atom; the spectrum of weakly driven fluorescence shows an additional 36% squeezing-induced narrowing. These effects can be observed using coupled-field and collective-polarization oscillators excited in a cavity containing N two-level atoms.

Sturm-Liouville Theory

Abstract: The chapter starts by considering ODEs subject to boundary conditions, and then considers the conditions under which the operator defining the ODE, together with the boundary conditions is Hermitian. This analysis, Sturm-Liouville theory, includes techniques for making an operator self-adjoint by multiplying its ODE by a weight factor and making an appropriate definition of the scalar product. The use of specific properties of ODEs to aid in the solution of boundary-value problems is illustrated for the Legendre and Hermite operators, and a two-region problem is used to illustrate the effect of matching conditions. The variation method (common in quantum mechanics) is described and illustrated.

Acinetobacter baumannii Strain M2 Produces Type IV Pili Which Play a Role in Natural Transformation and Twitching Motility but Not Surface-Associated Motility

Abstract: Acinetobacter baumannii is a Gram-negative, opportunistic pathogen. Recently, multiple A. baumannii genomes have been sequenced; these data have led to the identification of many genes predicted to encode proteins required for the biogenesis of type IV pili (TFP). However, there is no experimental evidence demonstrating that A. baumannii strains actually produce functional TFP. Here, we demonstrated that A. baumannii strain M2 is naturally transformable and capable of twitching motility, two classical TFP-associated phenotypes. Strains were constructed with mutations in pilA , pilD , and pilT , genes whose products have been well characterized in other systems. These mutants were no longer naturally transformable and did not exhibit twitching motility. These TFP-associated phenotypes were restored when these mutations were complemented. More PilA was detected on the surface of the pilT mutant than the parental strain, and TFP were visualized on the pilT mutant by transmission electron microscopy. Thus, A. baumannii produces functional TFP and utilizes TFP for both natural transformation and twitching motility. Several investigators have hypothesized that TFP might be responsible, in part, for the flagellum-independent surface-associated motility exhibited by many A. baumannii clinical isolates. We demonstrated that surface-associated motility was not dependent on the products of the pilA , pilD , and pilT genes and, by correlation, TFP. The identification of functional TFP in A. baumannii lays the foundation for future work determining the role of TFP in models of virulence that partially recapitulate human disease. IMPORTANCE Several investigators have documented the presence of genes predicted to encode proteins required for the biogenesis of TFP in many A. baumannii genomes. Furthermore, some have speculated that TFP may play a role in the unique surface-associated motility phenotype exhibited by many A. baumannii clinical isolates, yet there has been no experimental evidence to prove this. Unfortunately, progress in understanding the biology and virulence of A. baumannii has been slowed by the difficulty of constructing and complementing mutations in this species. Strain M2, a recently characterized clinical isolate, is amenable to genetic manipulation. We have established a reproducible system for the generation of marked and/or unmarked mutations using a modified recombineering strategy as well as a genetic complementation system utilizing a modified mini-Tn 7 element in strain M2. Using this strategy, we demonstrated that strain M2 produces TFP and that TFP are not required for surface-associated motility exhibited by strain M2.

Race-ethnic inequality and psychological distress: depressive symptoms from adolescence to young adulthood.

Abstract: Social inequality is well established in the mental health of race-ethnic groups, but little is known about this disparity from adolescence to young adulthood. This study examined differences in trajectories of depressive symptoms across 4 race-ethnic groups (Whites, Blacks, Hispanics, and Asians) using 3 waves of the National Longitudinal Study of Adolescent Health. Latent trajectory analyses showed race-ethnic variations among both females and males. Stressors were significantly related to depressive symptoms for all study members, but they accounted for symptom trajectories only among Black males and minority females. Persistent differences in trajectories for Blacks and Whites showed parallel slopes that did not converge over time. Neither background characteristics nor social resources (i.e., social support) altered this gap. However, social support represents a potential equalizer of these race-ethnic differences, owing to the ubiquitous nature of its protective effects.