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478 research outputs found

Kraichnan-Leith-Batchelor similarity theory and two-dimensional inverse cascades

Author: Undetermined U. (author)
Publication venue
Publication date: 2015
Field of study

We study the scaling properties and Kraichnan-Leith-Batchelor (KLB) theory of forced inverse cascades in generalized two-dimensional (2D) fluids (

\alpha

-turbulence models) simulated at resolution

8192^2

. We consider

\alpha=1

(surface quasigeostrophic flow),

\alpha=2

(2D vorticity dynamics) and

\alpha=3

. The forcing scale is well-resolved, a direct cascade is present and there is no large-scale dissipation. Coherent vortices spanning a range of sizes, most larger than the forcing scale, are present for both

\alpha=1

and

\alpha=2

. The active scalar field for

\alpha=3

contains comparatively few and small vortices. The energy spectral slopes in the inverse cascade are steeper than the KLB prediction

-(7-\alpha)/3

in all three systems. Since we stop the simulations well before the cascades have reached the domain scale, vortex formation and spectral steepening are not due to condensation effects; nor are they caused by large-scale dissipation, which is absent. One- and two-point pdfs, hyperflatness factors and structure functions indicate that the inverse cascades are intermittent and non-Gaussian over much of the inertial range for

\alpha=1

and

\alpha=2

, while the

\alpha=3

inverse cascade is much closer to Gaussian and non-intermittent. For

\alpha=3

the steep spectrum is close to that associated with enstrophy equipartition. Continuous wavelet analysis shows approximate KLB scaling

\mathcal{E}(k) \propto k^{-2}

(

\alpha=1

) and

\mathcal{E}(k) \propto k^{-5/3}

(

\alpha=2

) in the interstitial regions between the coherent vortices. Our results demonstrate that coherent vortex formation (

\alpha=1

and

\alpha=2

) and non-realizability (

\alpha=3

) cause 2D inverse cascades to deviate from the KLB predictions, but that the flow between the vortices exhibits KLB scaling and non-intermittent statistics for

\alpha=1

and

\alpha=2

. The results will appear in \cite{BurgessEA2015}, which has been accepted to the \emph{Journal of Fluid Mechanics}

TU Delft Repository

Guideline for Survey, Investigation, and Design of Black Spot Location (SID-BSL) and Its Application in Lampung Province, Indonesia

Author: Susilo Budi Hartanto
Susilo B.H.
Publication venue
Publication date: 20/04/2021
Field of study

In connection with the government's obligation to take responsibility for ensuring the safety of traffic and road transport for road users, it is necessary to conduct Surveys, Investigations, and Design of Black Spot Location (SID-BSL) to reduce traffic accident. Hence a guideline in conducting SID-BSL is needed. In this study, the author compiled a simple technique of prioritization for SID-BSL procedure and applies it to a research on National Roads in the Lampung Province. The technique of prioritization is simplified with four phase activities namely Preparation, Initial Analysis, Detail Survey, and Detail Analysis. The analysis technique is based on the ranking of Black Spot Locations using weighted accident number (WAN). Application procedure is applied on 237 events of accident on the National Roads in Lampung Province resulting five selected BSLs to be treated according to the availability of funds

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Civil Engineering Dimension (E-Journal)

Soluble and multivalent Jag1 DNA origami nanopatterns activate Notch without pulling force

Author: Wang Yang
Luca Vincent C.
Fördős Ferenc
Lentini Antonio
Smyrlaki Ioanna
Reinius Björn
Rocamonde-Lago Iris
Shen Boxuan
Högberg Björn
Teixeira Ana I.
Publication venue
Publication date: 18/01/2024
Field of study

Funding Information: The authors would like to acknowledge support from the NIH grant number R35GM133482 for V.C.L., the Knut and Alice Wallenberg Foundation (Grants KAW 2017.0114 for B.H. and A.I.T. and KAW 2017.0276 for B.H.), from the European Research Council ERC for B.H. (Acronym: Cell Track GA No. 724872) and A.I.T (Acronym: MechComm GA No. 617711), and from the Swedish Research Council for B.H. (grant no. 2019-01474) and from the Göran Gustafsson Foundation for B.H. And from the Academy of Finland for B.S. (grant no. 341908). lt-NES samples were obtained from, and initial culture protocols was made possible with the help of Anna Falk’s team and the iPS Core facility at Karolinska Institutet. Part of this work was performed at the Karolinska Institutet/SciLifeLab Protein Science Core Facility (PSF). Part of this work was performed at the Karolinska Institutet Biomedicum Imaging Core (BIC). EM data was collected at the Karolinska Institutet 3D-EM facility. Publisher Copyright: © 2024, The Author(s).The Notch signaling pathway has fundamental roles in embryonic development and in the nervous system. The current model of receptor activation involves initiation via a force-induced conformational change. Here, we define conditions that reveal pulling force-independent Notch activation using soluble multivalent constructs. We treat neuroepithelial stem-like cells with molecularly precise ligand nanopatterns displayed from solution using DNA origami. Notch signaling follows with clusters of Jag1, and with chimeric structures where most Jag1 proteins are replaced by other binders not targeting Notch. Our data rule out several confounding factors and suggest a model where Jag1 activates Notch upon prolonged binding without appearing to need a pulling force. These findings reveal a distinct mode of activation of Notch and lay the foundation for the development of soluble agonists.Peer reviewe

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