1,000 research outputs found
Proteins that contain a functional Z-DNA-binding domain localize to cytoplasmic stress granules
Long double-stranded RNA may undergo hyper-editing by adenosine deaminases that act on RNA (ADARs), where up to 50% of adenosine residues may be converted to inosine. However, although numerous RNAs may undergo hyper-editing, the role for inosine-containing hyper-edited double-stranded RNA in cells is poorly understood. Nevertheless, editing plays a critical role in mammalian cells, as highlighted by the analysis of ADAR-null mutants. In particular, the long form of ADAR1 (ADAR1(p150)) is essential for viability. Moreover, a number of studies have implicated ADAR1(p150) in various stress pathways. We have previously shown that ADAR1(p150) localized to cytoplasmic stress granules in HeLa cells following either oxidative or interferon-induced stress. Here, we show that the Z-DNA-binding domain (Zα(ADAR1)) exclusively found in ADAR1(p150) is required for its localization to stress granules. Moreover, we show that fusion of Zα(ADAR1) to either green fluorescent protein (GFP) or polypyrimidine binding protein 4 (PTB4) also results in their localization to stress granules. We additionally show that the Zα domain from other Z-DNA-binding proteins (ZBP1, E3L) is likewise sufficient for localization to stress granules. Finally, we show that Z-RNA or Z-DNA binding is important for stress granule localization. We have thus identified a novel role for Z-DNA-binding domains in mammalian cells
Novel Simulation-Inspired Roller Spreading Strategies for Fine and Highly Cohesive Metal Powders
When fine powders are to be used in powder bed metal additive manufacturing
(AM), a roller is typically utilized for spreading. However, the cohesive
nature of fine metal powder still presents challenges, resulting in low density
and/or inconsistent layers under sub-standard spreading conditions. Here,
through computational parameter studies with an integrated discrete
element-finite element (DEM-FEM) framework, we explore roller-based strategies
that are predicted to achieve highly cohesive powder layers. The exemplary
feedstock is a Ti-6Al-4V 0-20 um powder, that is emulated using a
self-similarity approach based on experimental calibration. The computational
studies explore novel roller kinematics including counter-rotation as well as
angular and transverse oscillation applied to standard rigid rollers as well as
coated rollers with compliant or non-adhesive surfaces. The results indicate
that most of these approaches allow to successfully spread highly cohesive
powders with high packing fraction (between 50%-60% in a single layer) and
layer uniformity provided that the angular/oscillatory, relative to the
transverse velocity, as well as the surface friction of the roller are
sufficiently high. Critically, these spreading approaches are shown to be very
robust with respect to varying substrate conditions (simulated by means of a
decrease in surface energy), which are likely to occur in LBPF or BJ, where
substrate characteristics are the result of a complex multi-physics (i.e.,
powder melting or binder infiltration) process. In particular, the combination
of the identified roller kinematics with compliant surface coatings, which are
known to reduce the risk of tool damage and particle streaking in the layers,
is recommended for future experimental investigation
Maternal serum concentrations of soluble endoglin and soluble vascular endothelial growth factor receptor 2 may predict the severity of villous hypoplasia in severe early-onset fetal growth restriction
Variational Perturbation Theory for Fokker-Planck Equation with Nonlinear Drift
We develop a recursive method for perturbative solutions of the Fokker-Planck
equation with nonlinear drift. The series expansion of the time-dependent
probability density in terms of powers of the coupling constant is obtained by
solving a set of first-order linear ordinary differential equations. Resumming
the series in the spirit of variational perturbation theory we are able to
determine the probability density for all values of the coupling constant.
Comparison with numerical results shows exponential convergence with increasing
order.Comment: Author Information under
http://www.theo-phys.uni-essen.de/tp/ags/pelster_dir
Interactions of liver Grp78 and Escherichia coli recombinant Grp78 with ATP: multiple species and disaggregation.
Spatial Mapping of Powder Layer Density for Metal Additive Manufacturing via X-ray Microscopy
Uniform powder spreading is a requisite for creating consistent, high-quality
components via powder bed additive manufacturing (AM), wherein layer density
and uniformity are complex functions of powder characteristics, spreading
kinematics, and mechanical boundary conditions. High spatial variation in
particle packing density, driven by the stochastic nature of the spreading
process, impedes optical interrogation of these layer attributes. Thus, we
present transmission X-ray imaging as a method for directly mapping the
effective depth of powder layers at process-relevant scale and resolution.
Specifically, we study layers of nominal 50-250 micrometer thickness, created
by spreading a selection of commercially obtained Ti-6Al-4V, 316 SS, and
Al-10Si-Mg powders into precision-depth templates. We find that powder layer
packing fraction may be predicted from a combination of the relative thickness
of the layer as compared to mean particle size, and flowability assessed by
macroscale powder angle of repose. Power spectral density analysis is
introduced as a tool for quantification of defect severity as a function of
morphology, and enables separate consideration of layer uniformity and
sparsity. Finally, spreading is studied using multi-layer templates, providing
insight into how particles interact with both previously deposited material and
abrupt changes in boundary condition. Experimental results are additionally
compared to a purpose-built discrete element method (DEM) powder spreading
simulation framework, clarifying the competing role of adhesive and
gravitational forces in layer uniformity and density, as well as particle
motion within the powder bed during spreading
Improved radiative corrections and proton charge form factor from the Rosenbluth separation technique
We investigate whether the apparent discrepancy between proton electric form
factor from measurements using the Rosenbluth separation technique and
polarization transfer method is due to the standard approximations employed in
radiative correction procedures. Inaccuracies due to both the peaking
approximation and the soft-photon approximation have been removed in our
simulation approach. In contrast to results from (e,e'p) experiments, we find
them in this case to be too small to explain the discrepancy.Comment: 6 pages, 3 figure
Board 317: Improving Undergraduate STEM Writing: A Collaboration Between Instructors and Writing Center Directors to Improve Peer-Writing Tutor Feedback
Undergraduate STEM writing skills, especially in engineering fields, need improvement. Yet students in engineering fields often do not value writing skills and underestimate the amount of writing they will do in their careers. University writing centers can be a helpful resource, but peer writing tutors need to be prepared for the differences between writing for the humanities and writing in STEM fields.
The Writing Assignment Tutor Training in STEM (WATTS) model is designed to improve tutor confidence and student writing. In this innovative training, the writing center supervisor collaborates with the STEM instructor to create a one-hour tutor-training where the tutors learn about the assignment content, vocabulary, and expectations. This multidisciplinary collaborative project builds on previous investigative work to determine the impact of WATTS on students, tutors, and faculty and to identify its mitigating and moderating effects. Data has been collected and analyzed from pre- and post- training surveys, interviews, and focus groups. In addition, the project studies WATTS effects on student writing pre- and post-tutoring. The team will use these results to develop a replicable, sustainable model for future expansion to other institutions and fields. By systematically collecting data and testing WATTS, the investigators will be able to identify its mitigating and moderating effects on different stakeholders and contribute valuable knowledge to STEM fields.
This approach assesses the elements of the model that have the most impact and the extent to which WATTS can be used to increase collaboration between engineering instructors and writing centers. The project enables the investigators to expand WATTS to additional engineering courses, test key factors with more instructors, refine the process, and position WATTS for dissemination to a broad audience.
As the cost of higher education rises, institutions are pressured to graduate students in four years and engineering curricula are becoming more complex. WATTS presents an economical, effective method to improve student writing in the discipline. Several factors indicate that it has the potential for broad dissemination and impact and will provide a foundation for a sustainable model for future work, as instructors become trainers for their colleagues, allowing additional ongoing expansion and implementation. WATTS serves as a model for institutions (large or small) to capitalize on existing infrastructure and resources to achieve large-scale improvements to undergraduate STEM writing while increasing interdisciplinary collaboration and institutional support
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