scholarly journals Using Artificial Seagrass for Promoting Positive Feedback Mechanisms in Seagrass Restoration

2021 ◽  
Vol 8 ◽  
Author(s):  
Jana Carus ◽  
Carmen Arndt ◽  
Boris Schröder ◽  
Moritz Thom ◽  
Raúl Villanueva ◽  
...  
Keyword(s):  
Positive Feedback ◽  
Ecosystem Engineer ◽  
Experimental Studies ◽  
Feedback Mechanism ◽  
Feedback Mechanisms ◽  
Seagrass Meadows ◽  
Open Questions ◽  
Sediment Stabilization ◽  
Seagrass Restoration ◽  
Positive Feedback Mechanism

Worldwide, seagrass meadows are under threat. Consequently, there is a strong need for seagrass restoration to guarantee the provision of related ecosystem services such as nutrient cycling, carbon sequestration and habitat provision. Seagrass often grows in vast meadows in which the presence of seagrass itself leads to a reduction of hydrodynamic energy. By modifying the environment, seagrass thus serves as foundation species and ecosystem engineer improving habitat quality for itself and other species as well as positively affecting its own fitness. On the downside, this positive feedback mechanism can render natural recovery of vanished and destroyed seagrass meadows impossible. An innovative approach to promote positive feedback mechanisms in seagrass restoration is to create an artificial seagrass (ASG) that mimics the facilitation function of natural seagrass. ASG could provide a window of opportunity with respect to suitable hydrodynamic and light conditions as well as sediment stabilization to allow natural seagrass to re-establish. Here, we give an overview of challenges and open questions for the application of ASG to promote seagrass restoration based on experimental studies and restoration trials and we propose a general approach for the design of an ASG produced from biodegradable materials. Considering positive feedback mechanisms is crucial to support restoration attempts. ASG provides promising benefits when habitat conditions are too harsh for seagrass meadows to re-establish themselves.

Effects of Positive Feedback on Crystallization Kinetics and Recalescence

2003 ◽  
Vol 806 ◽  
Author(s):  
Sven Bossuyt ◽  
A. Lindsay Greer
Keyword(s):  
Computer Simulation ◽  
Crystallization Kinetics ◽  
Metallic Glasses ◽  
Positive Feedback ◽  
Composition Dependence ◽  
Nucleation And Growth ◽  
Feedback Mechanism ◽  
Crystal Nucleation ◽  
Feedback Mechanisms ◽  
Positive Feedback Mechanism

ABSTRACTIn bulk metallic glasses cooled at nearly the critical cooling rate for glass formation, nucleation is observed to be spatially localized; nanocrystals are clustered together in spherical regions. This implies that a positive feedback mechanism locally increases the nucleation rate in the vicinity of other nucleation events. Linear stability analysis and computer simulation of differential equations describing crystal nucleation and growth are used to theoretically examine the plausibility of different potential feedback mechanisms. It is shown that interactions between different crystallizing phases can lead to counter-intuitive composition dependence of the crystallization kinetics in the case of non-polymorphic crystallization.

scholarly journals A positive feedback mechanism ensures proper assembly of the functional inner centromere during mitosis in human cells

2018 ◽  
Vol 294 (5) ◽  
pp. 1437-1450 ◽  
Author(s):  
Cai Liang ◽  
Zhenlei Zhang ◽  
Qinfu Chen ◽  
Haiyan Yan ◽  
Miao Zhang ◽  
...  
Keyword(s):  
Positive Feedback ◽  
Histone H3 ◽  
Causal Link ◽  
Feedback Mechanism ◽  
Histone H2a ◽  
Defective Mutant ◽  
Chromosomal Passenger ◽  
Phosphatase 2A ◽  
Elevated Rate ◽  
Positive Feedback Mechanism

The inner centromere region of a mitotic chromosome critically regulates sister chromatid cohesion and kinetochore–microtubule attachments. However, the molecular mechanism underlying inner centromere assembly remains elusive. Here, using CRISPR/Cas9-based gene editing in HeLa cells, we disrupted the interaction of Shugoshin 1 (Sgo1) with histone H2A phosphorylated on Thr-120 (H2ApT120) to selectively release Sgo1 from mitotic centromeres. Interestingly, cells expressing the H2ApT120-binding defective mutant of Sgo1 have an elevated rate of chromosome missegregation accompanied by weakened centromeric cohesion and decreased centromere accumulation of the chromosomal passenger complex (CPC), an integral part of the inner centromere and a key player in the correction of erroneous kinetochore–microtubule attachments. When artificially tethered to centromeres, a Sgo1 mutant defective in binding protein phosphatase 2A (PP2A) is not able to support proper centromeric cohesion and CPC accumulation, indicating that the Sgo1–PP2A interaction is essential for the integrity of mitotic centromeres. We further provide evidence indicating that Sgo1 protects centromeric cohesin to create a binding site for the histone H3–associated protein kinase Haspin, which not only inhibits the cohesin release factor Wapl and thereby strengthens centromeric cohesion but also phosphorylates histone H3 at Thr-3 to position CPC at inner centromeres. Taken together, our findings reveal a positive feedback–based mechanism that ensures proper assembly of the functional inner centromere during mitosis. They further suggest a causal link between centromeric cohesion defects and chromosomal instability in cancer cells.

scholarly journals Hedgehog signaling activates a positive feedback mechanism involving insulin-like growth factors to induce osteoblast differentiation

2015 ◽  
Vol 112 (15) ◽  
pp. 4678-4683 ◽  
Author(s):  
Yu Shi ◽  
Jianquan Chen ◽  
Courtney M. Karner ◽  
Fanxin Long
Keyword(s):  
Transcriptional Activation ◽  
Positive Feedback ◽  
Hedgehog Signaling ◽  
Osteoblast Differentiation ◽  
Akt Signaling ◽  
Feedback Mechanism ◽  
Genetic Deletion ◽  
Positive Feedback Mechanism ◽  
Igf Signaling

Hedgehog (Hh) signaling is essential for osteoblast differentiation in the endochondral skeleton during embryogenesis. However, the molecular mechanism underlying the osteoblastogenic role of Hh is not completely understood. Here, we report that Hh markedly induces the expression of insulin-like growth factor 2 (Igf2) that activates the mTORC2-Akt signaling cascade during osteoblast differentiation. Igf2-Akt signaling, in turn, stabilizes full-length Gli2 through Serine 230, thus enhancing the output of transcriptional activation by Hh. Importantly, genetic deletion of the Igf signaling receptor Igf1r specifically in Hh-responding cells diminishes bone formation in the mouse embryo. Thus, Hh engages Igf signaling in a positive feedback mechanism to activate the osteogenic program.

scholarly journals Survival and Proliferation of Neural Progenitor–Derived Glioblastomas Under Hypoxic Stress is Controlled by a CXCL12/CXCR4 Autocrine-Positive Feedback Mechanism

2016 ◽  
Vol 23 (5) ◽  
pp. 1250-1262 ◽  
Author(s):  
Anda-Alexandra Calinescu ◽  
Viveka Nand Yadav ◽  
Erica Carballo ◽  
Padma Kadiyala ◽  
Dustin Tran ◽  
...  
Keyword(s):  
Positive Feedback ◽  
Neural Progenitor ◽  
Feedback Mechanism ◽  
Hypoxic Stress ◽  
Positive Feedback Mechanism

Inverter design with positive feedback field-effect transistors

2021 ◽  
Author(s):  
Changhoon Lee ◽  
Changwoo Han ◽  
Changhwan Shin
Keyword(s):  
Positive Feedback ◽  
Computer Aided Design ◽  
Field Effect ◽  
Field Effect Transistors ◽  
Feedback Mechanism ◽  
Silicon On Insulator ◽  
Logic Device ◽  
Device Applications ◽  
Positive Feedback Mechanism ◽  
Switching Devices

Abstract As the physical size of semiconductor devices continues to be aggressively scaled down, feedback field-effect transistors (FBFET) with a positive feedback mechanism among a few promising steep switching devices have received attention as next-generation switching devices. Conventional FBFETs have been studied to explore their device performance. However, this has been restricted to the case of single FBFET; basic circuit designs with FBFETs have not been investigated extensively. In this work, we propose an inverter circuit design with silicon-on-insulator (SOI) FBFETs; we verified this inverter design with mixed-mode technology computer-aided design simulation. The basic principles and mechanisms for designing FBFET inverter circuits are explained because their configuration is different from conventional inverters. In addition, the device parameters necessary to optimize circuit construction are introduced for logic device applications.

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