701 research outputs found
Tissue-specific control of the endocycle by the anaphase promoting complex/cyclosome inhibitors UVI4 and DEL1
The endocycle represents a modified mitotic cell cycle that in plants is often coupled to cell enlargement and differentiation. Endocycle onset is controlled by activity of the Anaphase Promoting Complex/Cyclosome (APC/C), a multisubunit E3 ubiquitin ligase targeting cell-cycle factors for destruction. CELL CYCLE SWITCH52 (CCS52) proteins represent rate-limiting activator subunits of the APC/C. In Arabidopsis (Arabidopsis thaliana), mutations in either CCS52A1 or CCS52A2 activators result in a delayed endocycle onset, whereas their overexpression triggers increased DNA ploidy levels. Here, the relative contribution of the APC/C-CCS52A1 and APC/C-CCS52A2 complexes to different developmental processes was studied through analysis of their negative regulators, being the ULTRAVIOLET-B-INSENSITIVE4 protein and the DP-E2F-Like1 transcriptional repressor, respectively. Our data illustrate cooperative activity of the APC/C-CCS52A1 and APC/C-CCS52A2 complexes during root and trichome development, but functional interdependency during leaf development. Furthermore, we found APC/C-CCS52A1 activity to control CCS52A2 expression. We conclude that interdependency of CCS52A-controlled APC/C activity is controlled in a tissue-specific manner
The Security Twin Peaks
The feedback from architectural decisions to the elaboration of requirements is an established concept in the software engineering community. However, pinpointing the nature of this feedback in a precise way is a largely open problem. Often, the feedback is generically characterized as additional qualities that might be affected by an architect’s choice. This paper provides a practical perspective on this problem by leveraging architectural security patterns. The contribution of this paper is the Security Twin Peaks model, which serves as an operational framework to co-develop security in the requirements and the architectural artifacts
K8-Scalar: a workbench to compare autoscalers for container-orchestrated services (Artifact)
This artifact is an easy-to-use and extensible workbench exemplar, named K8-Scalar, which allows researchers to implement and evaluate different self-adaptive approaches to autoscaling container-orchestrated services. The workbench is based on Docker, a popular technology for easing the deployment of containerized software that also has been positioned as an enabler for reproducible research. The workbench also relies on a container orchestration framework: Kubernetes (K8s), the de-facto industry standard for orchestration and monitoring of elastically scalable container-based services. Finally, it integrates and extends Scalar, a generic testbed for evaluating the scalability of large-scale systems with support for evaluating the performance of autoscalers for database clusters.
The associated scholarly paper presents (i) the architecture and implementation of K8-Scalar and how a particular autoscaler can be plugged in, (ii) sketches the design of a Riemann-based autoscaler for database clusters, (iii) illustrates how to design, setup and analyze a series of experiments to configure and evaluate the performance of this autoscaler for a particular database (i.e., Cassandra) and a particular workload type, (iv) and validates the effectiveness of K8-scalar as a workbench for accurately comparing the performance of different auto-scaling strategies. Future work includes extending K8-Scalar with an improved research data management repository
Economic analysis of the health impacts of housing improvement studies: a systematic review
Background: Economic evaluation of public policies
has been advocated but rarely performed. Studies from a
systematic review of the health impacts of housing
improvement included data on costs and some economic
analysis. Examination of these data provides an
opportunity to explore the difficulties and the potential
for economic evaluation of housing.
Methods: Data were extracted from all studies included
in the systematic review of housing improvement which
had reported costs and economic analysis (n=29/45).
The reported data were assessed for their suitability to
economic evaluation. Where an economic analysis was
reported the analysis was described according to pre-set
definitions of various types of economic analysis used in
the field of health economics.
Results: 25 studies reported cost data on the
intervention and/or benefits to the recipients. Of these,
11 studies reported data which was considered
amenable to economic evaluation. A further four studies
reported conducting an economic evaluation. Three of
these studies presented a hybrid ‘balance sheet’
approach and indicated a net economic benefit
associated with the intervention. One cost-effectiveness
evaluation was identified but the data were unclearly
reported; the cost-effectiveness plane suggested that the
intervention was more costly and less effective than the
status quo.
Conclusions: Future studies planning an economic
evaluation need to (i) make best use of available data
and (ii) ensure that all relevant data are collected. To
facilitate this, economic evaluations should be planned
alongside the intervention with input from health
economists from the outset of the study. When
undertaken appropriately, economic evaluation provides
the potential to make significant contributions to
housing policy
Quantum Computation with Quantum Dots and Terahertz Cavity Quantum Electrodynamics
A quantum computer is proposed in which information is stored in the two
lowest electronic states of doped quantum dots (QDs). Many QDs are located in a
microcavity. A pair of gates controls the energy levels in each QD. A
Controlled Not (CNOT) operation involving any pair of QDs can be effected by a
sequence of gate-voltage pulses which tune the QD energy levels into resonance
with frequencies of the cavity or a laser. The duration of a CNOT operation is
estimated to be much shorter than the time for an electron to decohere by
emitting an acoustic phonon.Comment: Revtex 6 pages, 3 postscript figures, minor typos correcte
Rocks in the auxin stream : wound-induced auxin accumulation and ERF115 expression synergistically drive stem cell regeneration
Plants are known for their outstanding capacity to recover from various wounds and injuries. However, it remains largely unknown how plants sense diverse forms of injury and canalize existing developmental processes into the execution of a correct regenerative response. Auxin, a cardinal plant hormone with morphogen-like properties, has been previously implicated in the recovery from diverse types of wounding and organ loss. Here, through a combination of cellular imaging and in silico modeling, we demonstrate that vascular stem cell death obstructs the polar auxin flux, much alike rocks in a stream, and causes it to accumulate in the endodermis. This in turn grants the endodermal cells the capacity to undergo periclinal cell division to repopulate the vascular stem cell pool. Replenishment of the vasculature by the endodermis depends on the transcription factor ERF115, a wound-inducible regulator of stem cell division. Although not the primary inducer, auxin is required to maintain ERF115 expression. Conversely, ERF115 sensitizes cells to auxin by activating ARF5/MONOPTEROS, an auxin-responsive transcription factor involved in the global auxin response, tissue patterning, and organ formation. Together, the wound-induced auxin accumulation and ERF115 expression grant the endodermal cells stem cell activity. Our work provides a mechanistic model for wound-induced stem cell regeneration in which ERF115 acts as a wound-inducible stem cell organizer that interprets wound-induced auxin maxima
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