نتایج جستجو برای: nodal point
تعداد نتایج: 542742 فیلتر نتایج به سال:
The correct distribution and activity of secreted signaling proteins called morphogens is required for many developmental processes. Nodal morphogens play critical roles in embryonic axis formation in many organisms. Models proposed to generate the Nodal gradient include diffusivity, ligand processing, and a temporal activation window. But how the Nodal morphogen gradient forms in vivo remains ...
Secreted TGFbeta proteins of the Nodal family pattern the vertebrate body axes and induce mesoderm and endoderm . Nodal proteins can act as morphogens , but the mechanisms regulating their activity and signaling range are poorly understood. In particular, it has been unclear how inefficient processing or rapid turnover of the Nodal protein influences autocrine and paracrine signaling properties...
Growth factor signaling is essential for pattern formation, growth, differentiation, and maintenance of stem cell pluripotency. Nodal-related signaling factors are required for axis formation and germ layer specification from sea urchins to mammals. Maternal transcripts of the zebrafish Nodal factor, Squint (Sqt), are localized to future embryonic dorsal. The mechanisms by which maternal sqt/no...
This work proposes a new adaptive remeshing strategy based on the sensitivity of the point wise error in stresses with respect to the nodal coordinates, which is computed using the adjoint-state method. This sensitivity provides information about the influence of the discretization of each zone of the computational domain in the estimation of the error in stresses at a specific point. This info...
In this paper, we examine the numerical dispersion properties of the tetrahedral edge element in comparison to other edge and nodal elements. For all nodal elements as well as hexahedral edge elements, the phase error is always either positive or negative for waves propagating at any incidence angle, which means that the error accumulates as the wave propagates from element to element. This eff...
The first axis to be specified during vertebrate development is that between the site where gastrulation will begin and the opposite pole of the embryo (dorsoventral axis in amphibians and fish, anteroposterior in amniotes). This relies on Nodal activity, but different vertebrates differ in how this activity is positioned. In chick, the earliest known asymmetry is posterior expression of the TG...
dynamics of the mixed-state geometric phase of dissipative qubits. Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. The MIT Faculty has made this article openly available. Please share how this access benefits you. Your story matters. We investigate the geometric phase of a two-leve...
BACKGROUND The effect of internal mammary and medial supraclavicular lymph-node irradiation (regional nodal irradiation) added to whole-breast or thoracic-wall irradiation after surgery on survival among women with early-stage breast cancer is unknown. METHODS We randomly assigned women who had a centrally or medially located primary tumor, irrespective of axillary involvement, or an external...
Calculations are presented for the lowest 900 vibrational (J = 0) states of the LiCN floppy system for a two dimensional potential energy surface (rcN frozen). Most of these states lie well above the barrier separating the two linear isomers of the molecule and the point where the classical dynamics of the system becomes chaotic. Analysis of the wavefunctions of individual states in the high en...
BACKGROUND Acupuncture in humans can produce clinical effects via the central nervous system. However, the neural substrates of acupuncture's effects remain largely unknown. RESULTS We utilized functional MRI to investigate the topological efficiency of brain functional networks in eighteen healthy young adults who were scanned before and after acupuncture at the ST36 acupoints (ACUP) and its...
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