1,160 research outputs found
Visualizing the needle in the haystack: In situ hybridization with fluorescent dendrimers
In situ hybridization with 3DNA dendrimers is a novel tool for detecting low levels of mRNA in tissue sections and whole embryos. Fluorescently labeled dendrimers were used to identify cells that express mRNA for the skeletal muscle transcription factor MyoD in the early chick embryo. A small population of MyoD mRNA positive cells was found in the epiblast prior to the initiation of gastrulation, two days earlier than previously detected using enzymatic or radiolabeled probes for mRNA. When isolated from the epiblast and placed in culture, the MyoD mRNA positive cells were able to differentiate into skeletal muscle cells. These results demonstrate that DNA dendrimers are sensitive and precise tools for identifying low levels of mRNA in single cells and tissues
Excitation of self-localized spin-wave "bullets" by spin-polarized current in in-plane magnetized magnetic nano-contacts: a micromagnetic study
It was shown by micromagnetic simulation that a current-driven in-plane
magnetized magnetic nano-contact, besides a quasi-linear propagating
("Slonczewski") spin wave mode, can also support a nonlinear self-localized
spin wave "bullet" mode that exists in a much wider range of bias currents. The
frequency of the "bullet" mode lies below the spectrum of linear propagating
spin waves, which makes this mode evanescent and determines its spatial
localization. The threshold current for the excitation of the self-localized
"bullet" is substantially lower than for the linear propagating mode, but
finite-amplitude initial perturbations of magnetization are necessary to
generate a "bullet" in our numerical simulations, where thermal fluctuations
are neglected. Consequently, in these simulations the hysteretic switching
between the propagating and localized spin wave modes is found when the bias
current is varied.Comment: 27 pages, 5 figures, paper submitted to Physical Review
Visualizing the Needle in the Haystack: In Situ Hybridization With Fluorescent Dendrimers
In situ hybridization with 3DNA™ dendrimers is a novel tool for detecting low levels of mRNA in tissue sections and whole embryos. Fluorescently labeled dendrimers were used to identify cells that express mRNA for the skeletal muscle transcription factor MyoD in the early chick embryo. A small population of MyoD mRNA positive cells was found in the epiblast prior to the initiation of gastrulation, two days earlier than previously detected using enzymatic or radiolabeled probes for mRNA. When isolated from the epiblast and placed in culture, the MyoD mRNA positive cells were able to differentiate into skeletal muscle cells. These results demonstrate that DNA dendrimers are sensitive and precise tools for identifying low levels of mRNA in single cells and tissues
The Relationship Between HR Practices and Firm Performance: Examining Causal Order
Significant research attention has been devoted to examining the relationship between HR practices and firm performance, and the research support has assumed HR as the causal variable. Using data from 45 business units (with 62 data points), this study examines how measures of HR practices correlate with past, concurrent, and future operational performance measures. The results indicate that correlations with performance measures at all three times are both high and invariant, and that controlling for past or concurrent performance virtually eliminates the correlation of HR with future performance. Implications are discussed
Centennial-scale reductions in nitrogen availability in temperate forests of the United States
Forests cover 30% of the terrestrial Earth surface and are a major component of the global carbon
(C) cycle. Humans have doubled the amount of global reactive nitrogen (N), increasing deposition of N onto forests worldwide. However, other global changes—especially climate change and elevated atmospheric carbon dioxide concentrations—are increasing demand for N, the element limiting primary productivity in temperate forests, which could be reducing N availability. To determine the long-term, integrated effects of global changes on forest N cycling, we measured stable N isotopes in wood, a proxy for N supply relative to demand, on large spatial and temporal scales across the continental U.S.A. Here, we show that forest N availability has generally declined across much of the U.S. since at least 1850 C.E. with cool, wet forests demonstrating the greatest declines. Across sites, recent trajectories of N availability were independent of recent atmospheric N deposition rates, implying a minor role for modern N deposition on the trajectory of N status of North American forests. Our results demonstrate that current trends of global changes are likely to be consistent with forest oligotrophication into theforeseeable future, further constraining forest C fixation and potentially storage
Human Resources and the Resource Based View of the Firm
The resource-based view (RBV) of the firm has influenced the field of strategic human resource management (SHRM) in a number of ways. This paper explores the impact of the RBV on the theoretical and empirical development of SHRM. It explores how the fields of strategy and SHRM are beginning to converge around a number of issues, and proposes a number of implications of this convergence
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