Creep of (La0.55Sr0.45)0.99Mn1-yGayO3

Steady-state compressive creep was measured in (La0.55Sr0.45)0.99Mn1−yGayO3 at temperatures from 1200 to 1270 °C in air at stresses (σ) from 13 to 40 MPa. The Ga concentration was y = 0, 0.05, and 0.10. Strains to 0.14 were obtained. In the creep equation for strain rate, = An exp(−Q/RT), stress exponents (n) were between 1.3 and 1.7, indicating that diffusional flow is the dominant creep mechanism, and the activation energy (Q) was found to vary from 355 kJ mol−1 for y = 0 to 485 kJ mol−1 for y = 0.10

Phylogenetic analysis and temporal diversification of mosquitoes (Diptera: Culicidae) based on nuclear genes and morphology

<p>Abstract</p> <p>Background</p> <p>Phylogenetic analyses provide a framework for examining the evolution of morphological and molecular diversity, interpreting patterns in biogeography, and achieving a stable classification. The generic and suprageneric relationships within mosquitoes (Diptera: Culicidae) are poorly resolved, making these subjects difficult to address.</p> <p>Results</p> <p>We carried out maximum parsimony and maximum likelihood, including Bayesian, analyses on a data set consisting of six nuclear genes and 80 morphological characters to assess their ability to resolve relationships among 25 genera. We also estimated divergence times based on sequence data and fossil calibration points, using Bayesian relaxed clock methods. Strong support was recovered for the basal position and monophyly of the subfamily Anophelinae and the tribes Aedini and Sabethini of subfamily Culicinae. Divergence times for major culicid lineages date to the early Cretaceous.</p> <p>Conclusions</p> <p>Deeper relationships within the family remain poorly resolved, suggesting the need for additional taxonomic sampling. Our results support the notion of rapid radiations early in the diversification of mosquitoes.</p

Numerical Modeling of Evanescent-Wave Atom Optics

We numerically solve the time-dependent Schrodinger equation for a two-level atom interacting with an evanescent light field. The atom may be reflected or diffracted. Using the experimental parameter values we quantitatively model the evanescent field dopplerons (velocity-tuned resonances) observed by Stenlake et al. [Phys. Rev. A 49, 16 (1994)]. Besides successfully modeling the experiment, our approach provides complementary insights to the usual solution of the time-independent Schrodinger equation. We neglect spontaneous emission

The Changing of the Guard: The New American Labor Leader

This article analyzes recent changes in the leadership of international unions. There has been a trend toward leaders who are lifetime bureaucrats rather than rank-and-file members with charisma. This change toward more technocratic leadership is due to the different environment and new challenges that labor currently faces. The United Mine Workers is a good example of a union that has had many changes in the type of person who has become president, from the labor giant John L. Lewis to the 33-year-old lawyer Richard Trumka. The United Auto Workers is an example of a union whose leadership has been consistently drawn from the union hierarchy. The AFL-CIO has made a change in leadership from George Meany to the labor bureaucrat Lane Kirkland. There will probably be an increase in the number of women and minorities in top leadership positions in unions, but this will be a gradual increase.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66627/2/10.1177_000271628447300107.pd

Interaction, Emotion, and Collective Identities

[Excerpt] This chapter poses the question: How do emotional aspects of social interaction affect the emergence and salience of collective identities? I assume that social interaction inherently involves an implicit or explicit joint task—namely to accomplish some result that can only be produced with others. The most fundamental “task” of social interaction can be construed as the coordination and alignment of behavior, such that actors successfully conclude the interact ion episode. Essential to this task is a working consensus about definitions of self and other in the social situation, i.e., consensual self-other identities. A central component of my argument is that social interaction has emotional effects that vary with the success of actors at accomplishing this fundamental task. This paper theorizes the conditions under which emotional effects of social interaction promote collective identities that bridge or transcend self-other role identities

Mineral phosphorus drives glacier algal blooms on the Greenland Ice Sheet

Melting of the Greenland Ice Sheet is a leading cause of land-ice mass loss and cryosphere-attributed sea level rise. Blooms of pigmented glacier ice algae lower ice albedo and accelerate surface melting in the ice sheet’s southwest sector. Although glacier ice algae cause up to 13% of the surface melting in this region, the controls on bloom development remain poorly understood. Here we show a direct link between mineral phosphorus in surface ice and glacier ice algae biomass through the quantification of solid and fluid phase phosphorus reservoirs in surface habitats across the southwest ablation zone of the ice sheet. We demonstrate that nutrients from mineral dust likely drive glacier ice algal growth, and thereby identify mineral dust as a secondary control on ice sheet melting.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Field and Laboratory Studies Provide Insights into the Meaning of Day-Time Activity in a Subterranean Rodent (Ctenomys aff. knighti), the Tuco-Tuco

South American subterranean rodents (Ctenomys aff. knighti), commonly known as tuco-tucos, display nocturnal, wheel-running behavior under light-dark (LD) conditions, and free-running periods >24 h in constant darkness (DD). However, several reports in the field suggested that a substantial amount of activity occurs during daylight hours, leading us to question whether circadian entrainment in the laboratory accurately reflects behavior in natural conditions. We compared circadian patterns of locomotor activity in DD of animals previously entrained to full laboratory LD cycles (LD12∶12) with those of animals that were trapped directly from the field. In both cases, activity onsets in DD immediately reflected the previous dark onset or sundown. Furthermore, freerunning periods upon release into DD were close to 24 h indicating aftereffects of prior entrainment, similarly in both conditions. No difference was detected in the phase of activity measured with and without access to a running wheel. However, when individuals were observed continuously during daylight hours in a semi-natural enclosure, they emerged above-ground on a daily basis. These day-time activities consisted of foraging and burrow maintenance, suggesting that the designation of this species as nocturnal might be inaccurate in the field. Our study of a solitary subterranean species suggests that the circadian clock is entrained similarly under field and laboratory conditions and that day-time activity expressed only in the field is required for foraging and may not be time-dictated by the circadian pacemaker

Quantitative PCR reveals strong spatial and temporal variation of the wasting disease pathogen, Labyrinthula zosterae in northern European eelgrass (Zostera marina) beds

Seagrass beds are the foundation species of functionally important coastal ecosystems worldwide. The world’s largest losses of the widespread seagrass Zostera marina (eelgrass) have been reported as a consequence of wasting disease, an infection with the endophytic protist Labyrinthula zosterae. During one of the most extended epidemics in the marine realm, ~90% of East and Western Atlantic eelgrass beds died-off between 1932 and 1934. Today, small outbreaks continue to be reported, but the current extent of L. zosterae in European meadows is completely unknown. In this study we quantify the abundance and prevalence of the wasting disease pathogen among 19 Z. marina populations in northern European coastal waters, using quantitative PCR (QPCR) with primers targeting a species specific portion of the internally transcribed spacer (ITS1) of L. zosterae. Spatially, we found marked variation among sites with abundances varying between 0 and 126 cells mg−1 Z. marina dry weight (mean: 5.7 L. zosterae cells mg−1 Z. marina dry weight ±1.9 SE) and prevalences ranged from 0–88.9%. Temporarily, abundances varied between 0 and 271 cells mg−1 Z. marina dry weight (mean: 8.5±2.6 SE), while prevalences ranged from zero in winter and early spring to 96% in summer. Field concentrations accessed via bulk DNA extraction and subsequent QPCR correlated well with prevalence data estimated via isolation and cultivation from live plant tissue. L. zosterae was not only detectable in black lesions, a sign of Labyrinthula-induced necrosis, but also occurred in green, apparently healthy tissue. We conclude that L. zosterae infection is common (84% infected populations) in (northern) European eelgrass populations with highest abundances during the summer months. In the light of global climate change and increasing rate of marine diseases our data provide a baseline for further studies on the causes of pathogenic outbreaks of L. zosterae

Quantum Feedback Control: How to use Verification Theorems and Viscosity Solutions to Find Optimal Protocols

While feedback control has many applications in quantum systems, finding optimal control protocols for this task is generally challenging. So-called "verification theorems" and "viscosity solutions" provide two useful tools for this purpose: together they give a simple method to check whether any given protocol is optimal, and provide a numerical method for finding optimal protocols. While treatments of verification theorems usually use sophisticated mathematical language, this is not necessary. In this article we give a simple introduction to feedback control in quantum systems, and then describe verification theorems and viscosity solutions in simple language. We also illustrate their use with a concrete example of current interest.Comment: 12 pages, revtex