101 research outputs found
Concentration profiles of particles settling in the neutral and stratified atmospheric boundary layer
Misaligned Protoplanetary Disks in a Young Binary System
Many extrasolar planets follow orbits that differ from the nearly coplanar
and circular orbits found in our solar system; orbits may be eccentric or
inclined with respect to the host star's equator, and the population of giant
planets orbiting close to their host stars suggests significant orbital
migration. There is currently no consensus on what produces such orbits.
Theoretical explanations often invoke interactions with a binary companion star
on an orbit that is inclined relative to the planet's orbital plane. Such
mechanisms require significant mutual inclinations between planetary and binary
star orbital planes. The protoplanetary disks in a few young binaries are
misaligned, but these measurements are sensitive only to a small portion of the
inner disk, and the three-dimensional misalignment of the bulk of the
planet-forming disk mass has hitherto not been determined. Here we report that
the protoplanetary disks in the young binary system HK Tau are misaligned by
60{\deg}-68{\deg}, so one or both disks are significantly inclined to the
binary orbital plane. Our results demonstrate that the necessary conditions
exist for misalignment-driven mechanisms to modify planetary orbits, and that
these conditions are present at the time of planet formation, apparently due to
the binary formation process.Comment: Published in Nature, July 31 2014. 18 pages. This version has slight
differences from the final published version. Final version is available at
http://www.nature.com/nature/journal/v511/n7511/full/nature13521.htm
The Critical Richardson Number and Limits of Applicability of Local Similarity Theory in the Stable Boundary Layer
Measurements of atmospheric turbulence made over the Arctic pack ice during
the Surface Heat Budget of the Arctic Ocean experiment (SHEBA) are used to
determine the limits of applicability of Monin-Obukhov similarity theory (in
the local scaling formulation) in the stable atmospheric boundary layer. Based
on the spectral analysis of wind velocity and air temperature fluctuations, it
is shown that, when both of the gradient Richardson number, Ri, and the flux
Richardson number, Rf, exceed a 'critical value' of about 0.20 - 0.25, the
inertial subrange associated with the Richardson-Kolmogorov cascade dies out
and vertical turbulent fluxes become small. Some small-scale turbulence
survives even in this supercritical regime, but this is non-Kolmogorov
turbulence, and it decays rapidly with further increasing stability. Similarity
theory is based on the turbulent fluxes in the high-frequency part of the
spectra that are associated with energy-containing/flux-carrying eddies.
Spectral densities in this high-frequency band diminish as the
Richardson-Kolmogorov energy cascade weakens; therefore, the applicability of
local Monin-Obukhov similarity theory in stable conditions is limited by the
inequalities Ri < Ri_cr and Rf < Rf_cr. However, it is found that Rf_cr = 0.20
- 0.25 is a primary threshold for applicability. Applying this prerequisite
shows that the data follow classical Monin-Obukhov local z-less predictions
after the irrelevant cases (turbulence without the Richardson-Kolmogorov
cascade) have been filtered out.Comment: Boundary-Layer Meteorology (Manuscript submitted: 16 February 2012;
Accepted: 10 September 2012
An Improved Approach for Parameterizing Surface-Layer Turbulent Transfer Coefficients in Numerical Models
Guidelines for the use of flow cytometry and cell sorting in immunological studies (third edition)
The third edition of Flow Cytometry Guidelines provides the key aspects to consider when performing flow cytometry experiments and includes comprehensive sections describing phenotypes and functional assays of all major human and murine immune cell subsets. Notably, the Guidelines contain helpful tables highlighting phenotypes and key differences between human and murine cells. Another useful feature of this edition is the flow cytometry analysis of clinical samples with examples of flow cytometry applications in the context of autoimmune diseases, cancers as well as acute and chronic infectious diseases. Furthermore, there are sections detailing tips, tricks and pitfalls to avoid. All sections are written and peer-reviewed by leading flow cytometry experts and immunologists, making this edition an essential and state-of-the-art handbook for basic and clinical researchers
Using Temperature Fluctuation Measurements to Estimate Meteorological Inputs for Modelling Dispersion During Convective Conditions in Urban Areas
The interplay between HQ legitimation and subsidiary legitimacy judgments in HQ relocation : a social psychological approach
This paper marks a departure from the focus on external stakeholders in much research on legitimacy and multinational corporations, adopting a social psychological approach to study how MNCs build internal legitimacy for controversial decisions with their subsidiaries. We explore this through a longitudinal, real-time qualitative case study of a regional office relocation, since office relocations represent rare yet significant strategic decisions. We analyze the interplay between the legitimation strategies of senior managers and subsidiary legitimacy judgments, based in instrumental, relational, and moral considerations, and how the relationship between the two develops over time. From this analysis, we derive inductively a process model that reveals the dynamics of building internal legitimacy with subsidiaries, and how an MNC moves on even in the absence of full legitimacy, when dealing with controversial MNC decisions. The model highlights two important dynamics. The first is a dynamic between legitimation strategies and legitimacy judgments and how this is influenced by local subsidiary contexts. The second is a temporal dynamic in how both the legitimation strategies and legitimacy judgments evolve over time. Our model contributes to research on legitimacy in MNCs, what we know about tensions that characterize MNCâsubunit relationships, and research on headquarters relocation
Observational and Numerical Simulation Study of a Sequence of Eight Atmospheric Density Currents in Northern Spain
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