211 research outputs found
Charge Ordering and Phase Competition in the Layered Perovskite Lasr2mn2o7
Charge-lattice fluctuations are observed in the layered perovskite manganite
LaSr2Mn2O7 by Raman spectroscopy as high as 340 K and with decreasing
temperature they become static and form a charge ordered (CO) phase below
TCO=210 K. In the static regime, superlattice reflections are observed through
neutron and x-ray diffraction with a propagation vector (h+1/4,k-1/4,l).
Crystallographic analysis of the CO state demonstrates that the degree of
charge and orbital ordering in this manganite is weaker than the charge
ordering in three dimensional perovskite manganites. A TN=170K a type-A
antiferromagnetism (AF) develops and competes with the charge ordering, that
eventually melts below T*=100K. High resolution diffraction measurements
suggest that that CO- and AF-states do not coincide within the same region in
the material but rather co-exist as separate phases. The transition to type-A
antiferromagnetism at lower temperatures is characterized by the competition
between these two phases.Comment: 9 pages, 6 figure
Systematic evaluation of an atomic clock at 2e-18 total uncertainty
The pursuit of better atomic clocks has advanced many research areas,
providing better quantum state control, new insights in quantum science,
tighter limits on fundamental constant variation, and improved tests of
relativity. The record for the best stability and accuracy is currently held by
optical lattice clocks. This work takes an important step towards realizing the
full potential of a many-particle clock with a state-of-the-art stable laser.
Our 87Sr optical lattice clock now achieves fractional stability of 2.2e-16 at
1 s. With this improved stability, we perform a new accuracy evaluation of our
clock, reducing many systematic uncertainties that limited our previous
measurements, such as those in the lattice ac Stark shift, the atoms' thermal
environment, and the atomic response to room-temperature BBR. Our combined
measurements have reduced the total uncertainty of the JILA Sr clock to 2.1e-18
in fractional frequency units.Comment: Full published versio
Lattice Displacements Above Tc in the Layered Manganite La1.2Sr1.8Mn2O7
Neutron diffraction data presented in this paper demonstrates the relevance
of lattice displacement above TC, in our understanding of the evolution of the
crystal structure with temperature in the layered CMR manganite
La1.2Sr1.8Mn2O7. The anomalous temperature behavior of thermal diffuse
scattering (TDS) in La1.2Sr1.8Mn2O7 strongly suggests that it arises from
lattice displacements and correlates directly with anomalies in the
displacement parameters of the O- and Mn-atoms and Mn-O bond lengths. From our
measurements, the insulator - metal transition can be described as a transition
from a high temperature state with disordered Mn-O bond lengths to a low
temperature state with a more uniform distribution on Mn-O bonds. These
observations are in agreement with polaronic charge transport above TC in the
perovskite manganites; as electron hopping is responsible for bond disorder
above TC, below the transition where eg carries are delocalized, any lattice
displacements are uniformly averaged.Comment: 5 pages, 3 figures, submitted to Phys. Rev.
Identification of a small molecule yeast TORC1 inhibitor with a flow cytometry-based multiplex screen
TOR (target of rapamycin) is a serine/threonine kinase, evolutionarily conserved from yeast to
human, which functions as a fundamental controller of cell growth. The moderate clinical benefit
of rapamycin in mTOR-based therapy of many cancers favors the development of new TOR
inhibitors. Here we report a high throughput flow cytometry multiplexed screen using five GFPtagged
yeast clones that represent the readouts of four branches of the TORC1 signaling pathway
in budding yeast. Each GFP-tagged clone was differentially color-coded and the GFP signal of
each clone was measured simultaneously by flow cytometry, which allows rapid prioritization of
compounds that likely act through direct modulation of TORC1 or proximal signaling
components. A total of 255 compounds were confirmed in dose-response analysis to alter GFP
expression in one or more clones. To validate the concept of the high throughput screen, we have
characterized CID 3528206, a small molecule most likely to act on TORC1 as it alters GFP
expression in all five GFP clones in an analogous manner to rapamycin. We have shown that CID
3528206 inhibited yeast cell growth, and that CID 3528206 inhibited TORC1 activity both in vitro
and in vivo with EC50s of 150 nM and 3.9 μM, respectively. The results of microarray analysis
and yeast GFP collection screen further support the notion that CID 3528206 and rapamycin
modulate similar cellular pathways. Together, these results indicate that the HTS has identified a
potentially useful small molecule for further development of TOR inhibitors
Does Television Exposure Affect Emerging Adults' Attitudes and Assumptions About Sexual Relationships? Correlational and Experimental Confirmation
Because concern is frequently raised that TV's abundant yet stereotypical portrayals of sexual relationships may mislead young viewers, this study examined the effects of both regular viewing habits and experimental exposure on students' conceptions about sexual relationships. A multiethnic sample of 259 undergraduates aged 18–22 was assigned to view a set of clips depicting either 1 of 3 sexual stereotypes or neutral, nonsexual content. Participants then completed measures assessing their attitudes about sexual roles and relationships, their assumptions about the sexual experiences of their peers, and their regular viewing habits. Both correlational and experimental connections emerged between TV viewing and students' sexual attitudes and assumptions. More frequent and more involved viewing were repeatedly associated with students' support of the sexual stereotypes surveyed. Similarly, women exposed to clips representing a particular sexual stereotype were more likely to endorse that notion than were women exposed to nonsexual content. Finally, both experimental exposure and aspects of regular viewing significantly predicted students' sexual attitudes and assumptions, even with demographics and previous sexual experiences controlled.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45292/1/10964_2004_Article_364602.pd
Chikungunya as a cause of acute febrile illness in southern Sri Lanka
10.1371/journal.pone.0082259PLoS ONE812-POLN
A Historiometric Examination of Machiavellianism and a New Taxonomy of Leadership
Although researchers have extensively examined the relationship between charismatic leadership and Machiavellianism (Deluga, 2001; Gardner & Avolio, 1995; House & Howell, 1992), there has been a lack of investigation of Machiavellianism in relation to alternative forms of outstanding leadership. Thus, the purpose of this investigation was to examine the relationship between Machiavellianism and a new taxonomy of outstanding leadership comprised of charismatic, ideological, and pragmatic leaders. Using an historiometric approach, raters assessed Machiavellianism via the communications of 120 outstanding leaders in organizations across the domains of business, political, military, and religious institutions. Academic biographies were used to assess twelve general performance measures as well as twelve general controls and five communication specific controls. The results indicated that differing levels of Machiavellianism is evidenced across the differing leader types as well as differing leader orientation. Additionally, Machiavellianism appears negatively related to performance, though less so when type and orientation are taken into account.Yeshttps://us.sagepub.com/en-us/nam/manuscript-submission-guideline
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