TY - JOUR
AB - Metazoan development relies on the formation and remodeling of cell-cell contacts. Dynamic reorganization of adhesion receptors and the actomyosin cell cortex in space and time plays a central role in cell-cell contact formation and maturation. Nevertheless, how this process is mechanistically achieved when new contacts are formed remains unclear. Here, by building a biomimetic assay composed of progenitor cells adhering to supported lipid bilayers functionalized with E-cadherin ectodomains, we show that cortical F-actin flows, driven by the depletion of myosin-2 at the cell contact center, mediate the dynamic reorganization of adhesion receptors and cell cortex at the contact. E-cadherin-dependent downregulation of the small GTPase RhoA at the forming contact leads to both a depletion of myosin-2 and a decrease of F-actin at the contact center. At the contact rim, in contrast, myosin-2 becomes enriched by the retraction of bleb-like protrusions, resulting in a cortical tension gradient from the contact rim to its center. This tension gradient, in turn, triggers centrifugal F-actin flows, leading to further accumulation of F-actin at the contact rim and the progressive redistribution of E-cadherin from the contact center to the rim. Eventually, this combination of actomyosin downregulation and flows at the contact determines the characteristic molecular organization, with E-cadherin and F-actin accumulating at the contact rim, where they are needed to mechanically link the contractile cortices of the adhering cells.
AU - Arslan, Feyza N
AU - Hannezo, Edouard B
AU - Merrin, Jack
AU - Loose, Martin
AU - Heisenberg, Carl-Philipp J
ID - 14795
IS - 1
JF - Current Biology
SN - 0960-9822
TI - Adhesion-induced cortical flows pattern E-cadherin-mediated cell contacts
VL - 34
ER -
TY - JOUR
AB - Frequency-stable lasers form the back bone of precision measurements in science and technology. Such lasers typically attain their stability through frequency locking to reference cavities. State-of-the-art locking performances to date had been achieved using frequency modulation based methods, complemented with active drift cancellation systems. We demonstrate an all passive, modulation-free laser-cavity locking technique (squash locking) that utilizes changes in spatial beam ellipticity for error signal generation, and a coherent polarization post-selection for noise resilience. By comparing two identically built proof-of-principle systems, we show a frequency locking instability of 5×10−7 relative to the cavity linewidth at 10 s averaging. The results surpass the demonstrated performances of methods engineered over the last five decades, potentially enabling an advancement in the precision control of lasers, while creating avenues for bridging the performance gaps between industrial grade lasers with scientific ones due to the afforded simplicity and scalability.
AU - Diorico, Fritz R
AU - Zhutov, Artem
AU - Hosten, Onur
ID - 14802
IS - 1
JF - Optica
KW - Atomic and Molecular Physics
KW - and Optics
KW - Electronic
KW - Optical and Magnetic Materials
SN - 2334-2536
TI - Laser-cavity locking utilizing beam ellipticity: accessing the 10−7 instability scale relative to cavity linewidth
VL - 11
ER -
TY - JOUR
AB - We consider a natural problem dealing with weighted packet selection across a rechargeable link, which e.g., finds applications in cryptocurrency networks. The capacity of a link (u, v) is determined by how many nodes u and v allocate for this link. Specifically, the input is a finite ordered sequence of packets that arrive in both directions along a link. Given (u, v) and a packet of weight x going from u to v, node u can either accept or reject the packet. If u accepts the packet, the capacity on link (u, v) decreases by x. Correspondingly, v's capacity on
increases by x. If a node rejects the packet, this will entail a cost affinely linear in the weight of the packet. A link is “rechargeable” in the sense that the total capacity of the link has to remain constant, but the allocation of capacity at the ends of the link can depend arbitrarily on the nodes' decisions. The goal is to minimise the sum of the capacity injected into the link and the cost of rejecting packets. We show that the problem is NP-hard, but can be approximated efficiently with a ratio of (1+E) . (1+3) for some arbitrary E>0.
AU - Schmid, Stefan
AU - Svoboda, Jakub
AU - Yeo, Michelle X
ID - 14820
JF - Theoretical Computer Science
KW - General Computer Science
KW - Theoretical Computer Science
SN - 0304-3975
TI - Weighted packet selection for rechargeable links in cryptocurrency networks: Complexity and approximation
VL - 989
ER -
TY - JOUR
AB - Superconductor/semiconductor hybrid devices have attracted increasing interest in the past years. Superconducting electronics aims to complement semiconductor technology, while hybrid architectures are at the forefront of new ideas such as topological superconductivity and protected qubits. In this work, we engineer the induced superconductivity in two-dimensional germanium hole gas by varying the distance between the quantum well and the aluminum. We demonstrate a hard superconducting gap and realize an electrically and flux tunable superconducting diode using a superconducting quantum interference device (SQUID). This allows to tune the current phase relation (CPR), to a regime where single Cooper pair tunneling is suppressed, creating a sin(2y) CPR. Shapiro experiments complement this interpretation and the microwave drive allows to create a diode with ≈ 100% efficiency. The reported results open up the path towards integration of spin qubit devices, microwave resonators and (protected) superconducting qubits on the same silicon technology compatible platform.
AU - Valentini, Marco
AU - Sagi, Oliver
AU - Baghumyan, Levon
AU - de Gijsel, Thijs
AU - Jung, Jason
AU - Calcaterra, Stefano
AU - Ballabio, Andrea
AU - Aguilera Servin, Juan L
AU - Aggarwal, Kushagra
AU - Janik, Marian
AU - Adletzberger, Thomas
AU - Seoane Souto, Rubén
AU - Leijnse, Martin
AU - Danon, Jeroen
AU - Schrade, Constantin
AU - Bakkers, Erik
AU - Chrastina, Daniel
AU - Isella, Giovanni
AU - Katsaros, Georgios
ID - 14793
JF - Nature Communications
TI - Parity-conserving Cooper-pair transport and ideal superconducting diode in planar germanium
VL - 15
ER -
TY - JOUR
AB - We study a random matching problem on closed compact 2 -dimensional Riemannian manifolds (with respect to the squared Riemannian distance), with samples of random points whose common law is absolutely continuous with respect to the volume measure with strictly positive and bounded density. We show that given two sequences of numbers n and m=m(n) of points, asymptotically equivalent as n goes to infinity, the optimal transport plan between the two empirical measures μn and νm is quantitatively well-approximated by (Id,exp(∇hn))#μn where hn solves a linear elliptic PDE obtained by a regularized first-order linearization of the Monge-Ampère equation. This is obtained in the case of samples of correlated random points for which a stretched exponential decay of the α -mixing coefficient holds and for a class of discrete-time Markov chains having a unique absolutely continuous invariant measure with respect to the volume measure.
AU - Clozeau, Nicolas
AU - Mattesini, Francesco
ID - 14797
JF - Probability Theory and Related Fields
SN - 0178-8051
TI - Annealed quantitative estimates for the quadratic 2D-discrete random matching problem
ER -
TY - JOUR
AB - Mosaic analysis with double markers (MADM) technology enables the sparse labeling of genetically defined neurons. We present a protocol for time-lapse imaging of cortical projection neuron migration in mice using MADM. We describe steps for the isolation, culturing, and 4D imaging of neuronal dynamics in MADM-labeled brain tissue. While this protocol is compatible with other single-cell labeling methods, the MADM approach provides a genetic platform for the functional assessment of cell-autonomous candidate gene function and the relative contribution of non-cell-autonomous effects.
For complete details on the use and execution of this protocol, please refer to Hansen et al. (2022),1 Contreras et al. (2021),2 and Amberg and Hippenmeyer (2021).3
AU - Hansen, Andi H
AU - Hippenmeyer, Simon
ID - 14794
IS - 1
JF - STAR Protocols
TI - Time-lapse imaging of cortical projection neuron migration in mice using mosaic analysis with double markers
VL - 5
ER -
TY - JOUR
AB - The plant-signaling molecule auxin triggers fast and slow cellular responses across land plants and algae. The nuclear auxin pathway mediates gene expression and controls growth and development in land plants, but this pathway is absent from algal sister groups. Several components of rapid responses have been identified in Arabidopsis, but it is unknown if these are part of a conserved mechanism. We recently identified a fast, proteome-wide phosphorylation response to auxin. Here, we show that this response occurs across 5 land plant and algal species and converges on a core group of shared targets. We found conserved rapid physiological responses to auxin in the same species and identified rapidly accelerated fibrosarcoma (RAF)-like protein kinases as central mediators of auxin-triggered phosphorylation across species. Genetic analysis connects this kinase to both auxin-triggered protein phosphorylation and rapid cellular response, thus identifying an ancient mechanism for fast auxin responses in the green lineage.
AU - Kuhn, Andre
AU - Roosjen, Mark
AU - Mutte, Sumanth
AU - Dubey, Shiv Mani
AU - Carrillo Carrasco, Vanessa Polet
AU - Boeren, Sjef
AU - Monzer, Aline
AU - Koehorst, Jasper
AU - Kohchi, Takayuki
AU - Nishihama, Ryuichi
AU - Fendrych, Matyas
AU - Sprakel, Joris
AU - Friml, Jiří
AU - Weijers, Dolf
ID - 14826
IS - 1
JF - Cell
KW - General Biochemistry
KW - Genetics and Molecular Biology
SN - 0092-8674
TI - RAF-like protein kinases mediate a deeply conserved, rapid auxin response
VL - 187
ER -
TY - JOUR
AB - Production of hydrogen at large scale requires development of non-noble, inexpensive, and high-performing catalysts for constructing water-splitting devices. Herein, we report the synthesis of Zn-doped NiO heterostructure (ZnNiO) catalysts at room temperature via a coprecipitation method followed by drying (at 80 °C, 6 h) and calcination at an elevated temperature of 400 °C for 5 h under three distinct conditions, namely, air, N2, and vacuum. The vacuum-synthesized catalyst demonstrates a low overpotential of 88 mV at −10 mA cm–2 and a small Tafel slope of 73 mV dec–1 suggesting relatively higher charge transfer kinetics for hydrogen evolution reactions (HER) compared with the specimens synthesized under N2 or O2 atmosphere. It also demonstrates an oxygen evolution (OER) overpotential of 260 mV at 10 mA cm–2 with a low Tafel slope of 63 mV dec–1. In a full-cell water-splitting device, the vacuum-synthesized ZnNiO heterostructure demonstrates a cell voltage of 1.94 V at 50 mA cm–2 and shows remarkable stability over 24 h at a high current density of 100 mA cm–2. It is also demonstrated in this study that Zn-doping, surface, and interface engineering in transition-metal oxides play a crucial role in efficient electrocatalytic water splitting. Also, the results obtained from density functional theory (DFT + U = 0–8 eV), where U is the on-site Coulomb repulsion parameter also known as Hubbard U, based electronic structure calculations confirm that Zn doping constructively modifies the electronic structure, in both the valence band and the conduction band, and found to be suitable in tailoring the carrier’s effective masses of electrons and holes. The decrease in electron’s effective masses together with large differences between the effective masses of electrons and holes is noticed, which is found to be mainly responsible for achieving the best water-splitting performance from a 9% Zn-doped NiO sample prepared under vacuum.
AU - Kiran, Gundegowda Kalligowdanadoddi
AU - Singh, Saurabh
AU - Mahato, Neelima
AU - Sreekanth, Thupakula Venkata Madhukar
AU - Dillip, Gowra Raghupathy
AU - Yoo, Kisoo
AU - Kim, Jonghoon
ID - 14828
IS - 1
JF - ACS Applied Energy Materials
KW - Electrical and Electronic Engineering
KW - Materials Chemistry
KW - Electrochemistry
KW - Energy Engineering and Power Technology
KW - Chemical Engineering (miscellaneous)
SN - 2574-0962
TI - Interface engineering modulation combined with electronic structure modification of Zn-doped NiO heterostructure for efficient water-splitting activity
VL - 7
ER -
TY - JOUR
AB - Bacteria divide by binary fission. The protein machine responsible for this process is the divisome, a transient assembly of more than 30 proteins in and on the surface of the cytoplasmic membrane. Together, they constrict the cell envelope and remodel the peptidoglycan layer to eventually split the cell into two. For Escherichia coli, most molecular players involved in this process have probably been identified, but obtaining the quantitative information needed for a mechanistic understanding can often not be achieved from experiments in vivo alone. Since the discovery of the Z-ring more than 30 years ago, in vitro reconstitution experiments have been crucial to shed light on molecular processes normally hidden in the complex environment of the living cell. In this review, we summarize how rebuilding the divisome from purified components – or at least parts of it - have been instrumental to obtain the detailed mechanistic understanding of the bacterial cell division machinery that we have today.
AU - Radler, Philipp
AU - Loose, Martin
ID - 14834
IS - 1
JF - European Journal of Cell Biology
KW - Cell Biology
KW - General Medicine
KW - Histology
KW - Pathology and Forensic Medicine
SN - 0171-9335
TI - A dynamic duo: Understanding the roles of FtsZ and FtsA for Escherichia coli cell division through in vitro approaches
VL - 103
ER -
TY - JOUR
AB - De novo heterozygous variants in KCNC2 encoding the voltage-gated potassium (K+) channel subunit Kv3.2 are a recently described cause of developmental and epileptic encephalopathy (DEE). A de novo variant in KCNC2 c.374G > A (p.Cys125Tyr) was identified via exome sequencing in a patient with DEE. Relative to wild-type Kv3.2, Kv3.2-p.Cys125Tyr induces K+ currents exhibiting a large hyperpolarizing shift in the voltage dependence of activation, accelerated activation, and delayed deactivation consistent with a relative stabilization of the open conformation, along with increased current density. Leveraging the cryogenic electron microscopy (cryo-EM) structure of Kv3.1, molecular dynamic simulations suggest that a strong π-π stacking interaction between the variant Tyr125 and Tyr156 in the α-6 helix of the T1 domain promotes a relative stabilization of the open conformation of the channel, which underlies the observed gain of function. A multicompartment computational model of a Kv3-expressing parvalbumin-positive cerebral cortex fast-spiking γ-aminobutyric acidergic (GABAergic) interneuron (PV-IN) demonstrates how the Kv3.2-Cys125Tyr variant impairs neuronal excitability and dysregulates inhibition in cerebral cortex circuits to explain the resulting epilepsy.
AU - Clatot, Jerome
AU - Currin, Christopher
AU - Liang, Qiansheng
AU - Pipatpolkai, Tanadet
AU - Massey, Shavonne L.
AU - Helbig, Ingo
AU - Delemotte, Lucie
AU - Vogels, Tim P
AU - Covarrubias, Manuel
AU - Goldberg, Ethan M.
ID - 14841
IS - 3
JF - Proceedings of the National Academy of Sciences of the United States of America
TI - A structurally precise mechanism links an epilepsy-associated KCNC2 potassium channel mutation to interneuron dysfunction
VL - 121
ER -
TY - JOUR
AB - We study a linear rotor in a bosonic bath within the angulon formalism. Our focus is on systems where isotropic or anisotropic impurity-boson interactions support a shallow bound state. To study the fate of the angulon in the vicinity of bound-state formation, we formulate a beyond-linear-coupling angulon Hamiltonian. First, we use it to study attractive, spherically symmetric impurity-boson interactions for which the linear rotor can be mapped onto a static impurity. The well-known polaron formalism provides an adequate description in this limit. Second, we consider anisotropic potentials, and show that the presence of a shallow bound state with pronounced anisotropic character leads to a many-body instability that washes out the angulon dynamics.
AU - Dome, Tibor
AU - Volosniev, Artem
AU - Ghazaryan, Areg
AU - Safari, Laleh
AU - Schmidt, Richard
AU - Lemeshko, Mikhail
ID - 14845
IS - 1
JF - Physical Review B
SN - 2469-9950
TI - Linear rotor in an ideal Bose gas near the threshold for binding
VL - 109
ER -
TY - JOUR
AB - The physical conditions giving rise to high escape fractions of ionizing radiation (LyC fesc) in star-forming galaxies – most likely protagonists of cosmic reionization – are not yet fully understood. Using the VLT/MUSE observations of ∼1400 Ly α emitters at 2.9 < z < 6.7, we compare stacked rest-frame UV spectra of candidates for LyC leakers and non-leakers selected based on their Ly α profiles. We find that the stacks of potential LyC leakers, i.e. galaxies with narrow, symmetric Ly α profiles with small peak separation, generally show (i) strong nebular O iii]λ1666, [Si iii]λ1883, and [C iii]λ1907 +C iii]λ1909 emission, indicating a high-ionization state of the interstellar medium (ISM); (ii) high equivalent widths of He iiλ1640 (∼1 − 3 Å), suggesting the presence of hard ionizing radiation fields; (iii) Si ii*λ1533 emission, revealing substantial amounts of neutral hydrogen off the line of sight; (iv) high C ivλλ1548,1550 to [C iii]λ1907 +C iii]λ1909 ratios (C iv/C iii] ≳0.75) , signalling the presence of low column density channels in the ISM. In contrast, the stacks with broad, asymmetric Ly α profiles with large peak separation show weak nebular emission lines, low He iiλ1640 equivalent widths (≲1 Å), and low C iv/C iii] (≲0.25), implying low-ionization states and high-neutral hydrogen column densities. Our results suggest that C iv/C iii] might be sensitive to the physical conditions that govern LyC photon escape, providing a promising tool for identification of ionizing sources among star-forming galaxies in the epoch of reionization.
AU - Kramarenko, Ivan
AU - Kerutt, J
AU - Verhamme, A
AU - Oesch, P A
AU - Barrufet, L
AU - Matthee, Jorryt J
AU - Kusakabe, H
AU - Goovaerts, I
AU - Thai, T T
ID - 14852
IS - 4
JF - Monthly Notices of the Royal Astronomical Society
KW - Space and Planetary Science
KW - Astronomy and Astrophysics
SN - 0035-8711
TI - Linking UV spectral properties of MUSE Ly α emitters at z ≳ 3 to Lyman continuum escape
VL - 527
ER -
TY - JOUR
AB - Elaborate sexual signals are thought to have evolved and be maintained to serve as honest indicators of signaller quality. One measure of quality is health, which can be affected by parasite infection. Cnemaspis mysoriensis is a diurnal gecko that is often infested with ectoparasites in the wild, and males of this species express visual (coloured gular patches) and chemical (femoral gland secretions) traits that receivers could assess during social interactions. In this paper, we tested whether ectoparasites affect individual health, and whether signal quality is an indicator of ectoparasite levels. In wild lizards, we found that ectoparasite level was negatively correlated with body condition in both sexes. Moreover, some characteristics of both visual and chemical traits in males were strongly associated with ectoparasite levels. Specifically, males with higher ectoparasite levels had yellow gular patches with lower brightness and chroma, and chemical secretions with a lower proportion of aromatic compounds. We then determined whether ectoparasite levels in males influence female behaviour. Using sequential choice trials, wherein females were provided with either the visual or the chemical signals of wild-caught males that varied in ectoparasite level, we found that only chemical secretions evoked an elevated female response towards less parasitised males. Simultaneous choice trials in which females were exposed to the chemical secretions from males that varied in parasite level further confirmed a preference for males with lower parasites loads. Overall, we find that although health (body condition) or ectoparasite load can be honestly advertised through multiple modalities, the parasite-mediated female response is exclusively driven by chemical signals.
AU - Pal, Arka
AU - Joshi, Mihir
AU - Thaker, Maria
ID - 14850
IS - 1
JF - Journal of Experimental Biology
KW - Insect Science
KW - Molecular Biology
KW - Animal Science and Zoology
KW - Aquatic Science
KW - Physiology
KW - Ecology
KW - Evolution
KW - Behavior and Systematics
SN - 1477-9145
TI - Too much information? Males convey parasite levels using more signal modalities than females utilise
VL - 227
ER -
TY - THES
AB - In nature, different species find their niche in a range of environments, each with its unique characteristics. While some thrive in uniform (homogeneous) landscapes where environmental conditions stay relatively consistent across space, others traverse the complexities of spatially heterogeneous terrains. Comprehending how species are distributed and how they interact within these landscapes holds the key to gaining insights into their evolutionary dynamics while also informing conservation and management strategies.
For species inhabiting heterogeneous landscapes, when the rate of dispersal is low compared to spatial fluctuations in selection pressure, localized adaptations may emerge. Such adaptation in response to varying selection strengths plays an important role in the persistence of populations in our rapidly changing world. Hence, species in nature are continuously in a struggle to adapt to local environmental conditions, to ensure their continued survival. Natural populations can often adapt in time scales short enough for evolutionary changes to influence ecological dynamics and vice versa, thereby creating a feedback between evolution and demography. The analysis of this feedback and the relative contributions of gene flow, demography, drift, and natural selection to genetic variation and differentiation has remained a recurring theme in evolutionary biology. Nevertheless, the effective role of these forces in maintaining variation and shaping patterns of diversity is not fully understood. Even in homogeneous environments devoid of local adaptations, such understanding remains elusive. Understanding this feedback is crucial, for example in determining the conditions under which extinction risk can be mitigated in peripheral populations subject to deleterious mutation accumulation at the edges of species’ ranges
as well as in highly fragmented populations.
In this thesis we explore both uniform and spatially heterogeneous metapopulations, investigating and providing theoretical insights into the dynamics of local adaptation in the latter and examining the dynamics of load and extinction as well as the impact of joint ecological and evolutionary (eco-evolutionary) dynamics in the former. The thesis is divided into 5 chapters.
Chapter 1 provides a general introduction into the subject matter, clarifying concepts and ideas used throughout the thesis. In chapter 2, we explore how fast a species distributed across a heterogeneous landscape adapts to changing conditions marked by alterations in carrying capacity, selection pressure, and migration rate.
In chapter 3, we investigate how migration selection and drift influences adaptation and the maintenance of variation in a metapopulation with three habitats, an extension of previous models of adaptation in two habitats. We further develop analytical approximations for the critical threshold required for polymorphism to persist.
The focus of chapter 4 of the thesis is on understanding the interplay between ecology and evolution as coupled processes. We investigate how eco-evolutionary feedback between migration, selection, drift, and demography influences eco-evolutionary outcomes in marginal populations subject to deleterious mutation accumulation. Using simulations as well as theoretical approximations of the coupled dynamics of population size and allele frequency, we analyze how gene flow from a large mainland source influences genetic load and population size on an island (i.e., in a marginal population) under genetically realistic assumptions. Analyses of this sort are important because small isolated populations, are repeatedly affected by complex interactions between ecological and evolutionary processes, which can lead to their death. Understanding these interactions can therefore provide an insight into the conditions under which extinction risk can be mitigated in peripheral populations thus, contributing to conservation and restoration efforts.
Chapter 5 extends the analysis in chapter 4 to consider the dynamics of load (due to deleterious mutation accumulation) and extinction risk in a metapopulation. We explore the role of gene flow, selection, and dominance on load and extinction risk and further pinpoint critical thresholds required for metapopulation persistence.
Overall this research contributes to our understanding of ecological and evolutionary mechanisms that shape species’ persistence in fragmented landscapes, a crucial foundation for successful conservation efforts and biodiversity management.
AU - Olusanya, Oluwafunmilola O
ID - 14711
SN - 2663 - 337X
TI - Local adaptation, genetic load and extinction in metapopulations
ER -
TY - CONF
AB - A face in a curve arrangement is called popular if it is bounded by the same curve multiple times. Motivated by the automatic generation of curved nonogram puzzles, we investigate possibilities to eliminate the popular faces in an arrangement by inserting a single additional curve. This turns out to be NP-hard; however, it becomes tractable when the number of popular faces is small: We present a probabilistic FPT-approach in the number of popular faces.
AU - De Nooijer, Phoebe
AU - Terziadis, Soeren
AU - Weinberger, Alexandra
AU - Masárová, Zuzana
AU - Mchedlidze, Tamara
AU - Löffler, Maarten
AU - Rote, Günter
ID - 14888
SN - 0302-9743
T2 - 31st International Symposium on Graph Drawing and Network Visualization
TI - Removing popular faces in curve arrangements
VL - 14466
ER -
TY - JOUR
AB - Episodic memories are encoded by experience-activated neuronal ensembles that remain necessary and sufficient for recall. However, the temporal evolution of memory engrams after initial encoding is unclear. In this study, we employed computational and experimental approaches to examine how the neural composition and selectivity of engrams change with memory consolidation. Our spiking neural network model yielded testable predictions: memories transition from unselective to selective as neurons drop out of and drop into engrams; inhibitory activity during recall is essential for memory selectivity; and inhibitory synaptic plasticity during memory consolidation is critical for engrams to become selective. Using activity-dependent labeling, longitudinal calcium imaging and a combination of optogenetic and chemogenetic manipulations in mouse dentate gyrus, we conducted contextual fear conditioning experiments that supported our model’s predictions. Our results reveal that memory engrams are dynamic and that changes in engram composition mediated by inhibitory plasticity are crucial for the emergence of memory selectivity.
AU - Feitosa Tomé, Douglas
AU - Zhang, Ying
AU - Aida, Tomomi
AU - Mosto, Olivia
AU - Lu, Yifeng
AU - Chen, Mandy
AU - Sadeh, Sadra
AU - Roy, Dheeraj S.
AU - Clopath, Claudia
ID - 14887
JF - Nature Neuroscience
SN - 1097-6256
TI - Dynamic and selective engrams emerge with memory consolidation
ER -
TY - JOUR
AB - The phytohormone auxin and its directional transport through tissues play a fundamental role in development of higher plants. This polar auxin transport predominantly relies on PIN-FORMED (PIN) auxin exporters. Hence, PIN polarization is crucial for development, but its evolution during the rise of morphological complexity in land plants remains unclear. Here, we performed a cross-species investigation by observing the trafficking and localization of endogenous and exogenous PINs in two bryophytes, Physcomitrium patens and Marchantia polymorpha, and in the flowering plant Arabidopsis thaliana. We confirmed that the GFP fusion did not compromise the auxin export function of all examined PINs by using radioactive auxin export assay and by observing the phenotypic changes in transgenic bryophytes. Endogenous PINs polarize to filamentous apices, while exogenous Arabidopsis PINs distribute symmetrically on the membrane in both bryophytes. In Arabidopsis root epidermis, bryophytic PINs show no defined polarity. Pharmacological interference revealed a strong cytoskeleton dependence of bryophytic but not Arabidopsis PIN polarization. The divergence of PIN polarization and trafficking is also observed within the bryophyte clade and between tissues of individual species. These results collectively reveal a divergence of PIN trafficking and polarity mechanisms throughout land plant evolution and a co-evolution of PIN sequence-based and cell-based polarity mechanisms.
AU - Tang, Han
AU - Lu, KJ
AU - Zhang, Y
AU - Cheng, YL
AU - Tu, SL
AU - Friml, Jiří
ID - 14251
IS - 1
JF - Plant Communications
SN - 2590-3462
TI - Divergence of trafficking and polarization mechanisms for PIN auxin transporters during land plant evolution
VL - 5
ER -
TY - JOUR
AB - It is a basic principle that an effect cannot come before the cause. Dispersive relations that follow from this fundamental fact have proven to be an indispensable tool in physics and engineering. They are most powerful in the domain of linear response where they are known as Kramers-Kronig relations. However, when it comes to nonlinear phenomena the implications of causality are much less explored, apart from several notable exceptions. Here in this paper we demonstrate how to apply the dispersive formalism to analyze the ultrafast nonlinear response in the context of the paradigmatic nonlinear Kerr effect. We find that the requirement of causality introduces a noticeable effect even under assumption that Kerr effect is mediated by quasi-instantaneous off-resonant electronic hyperpolarizability. We confirm this by experimentally measuring the time-resolved Kerr dynamics in GaAs by means of a hybrid pump-probe Mach-Zehnder interferometer and demonstrate the presence of an intrinsic lagging between amplitude and phase responses as predicted by dispersive analysis. Our results describe a general property of the time-resolved nonlinear processes thereby highlighting the importance of accounting for dispersive effects in the nonlinear optical processes involving ultrashort pulses.
AU - Lorenc, Dusan
AU - Alpichshev, Zhanybek
ID - 14886
IS - 1
JF - Physical Review Research
TI - Dispersive effects in ultrafast nonlinear phenomena: The case of optical Kerr effect
VL - 6
ER -
TY - THES
AU - Chiossi, Heloisa
ID - 14821
SN - 2663 - 337X
TI - Adaptive hierarchical representations in the hippocampus
ER -
TY - JOUR
AB - Global services like navigation, communication, and Earth observation have increased dramatically in the 21st century due to advances in outer space industries. But as orbits become increasingly crowded with both satellites and inevitable space debris pollution, continued operations become endangered by the heightened risks of debris collisions in orbit. Kessler Syndrome is the term for when a critical threshold of orbiting debris triggers a runaway positive feedback loop of debris collisions, creating debris congestion that can render orbits unusable. As this potential tipping point becomes more widely recognized, there have been renewed calls for debris mitigation and removal. Here, we combine complex systems and social-ecological systems approaches to study how these efforts may affect space debris accumulation and the likelihood of reaching Kessler Syndrome. Specifically, we model how debris levels are affected by future launch rates, cleanup activities, and collisions between extant debris. We contextualize and interpret our dynamic model within a discussion of existing space debris governance and other social, economic, and geopolitical factors that may influence effective collective management of the orbital commons. In line with previous studies, our model finds that debris congestion may be reached in less than 200 years, though a holistic management strategy combining removal and mitigation actions can avoid such outcomes while continuing space activities. Moreover, although active debris removal may be particularly effective, the current lack of market and governance support may impede its implementation. Research into these critical dynamics and the multi-faceted variables that influence debris outcomes can support policymakers in curating impactful governance strategies and realistic transition pathways to sustaining debris-free orbits. Overall, our study is useful for communicating about space debris sustainability in policy and education settings by providing an exploration of policy portfolio options supported by a simple and clear social-ecological modeling approach.
AU - Nomura, Keiko
AU - Rella, Simon
AU - Merritt, Haily
AU - Baltussen, Mathieu
AU - Bird, Darcy
AU - Tjuka, Annika
AU - Falk, Dan
ID - 14901
IS - 1
JF - International Journal of the Commons
KW - Sociology and Political Science
SN - 1875-0281
TI - Tipping points of space debris in low earth orbit
VL - 18
ER -