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Frank M Hilker, Marta Paliga, Ezio Venturino
Social predators benefit from cooperation in the form of increased hunting success, but may be at higher risk of disease infection due to living in groups. Here, we use mathematical modeling to investigate the impact of disease transmission on the population dynamics benefits provided by group hunting. We consider a predator-prey model with foraging facilitation that can induce strong Allee effects in the predators. We extend this model by an infectious disease spreading horizontally and vertically in the predator population...
August 9, 2017: Bulletin of Mathematical Biology
Yetsedaw A Tsegaw, Pritam Eknath Kadam, Niklas Tötsch, Elsa Sanchez-Garcia, Wolfram Sander
p-Tolyl(trifluoromethyl) carbene and the related fluorenyl(trifluoromethyl)carbene were synthesized in solid argon and characterized by IR, UV-vis, and EPR spectroscopy as well as by quantum mechanical calculations. The carbenes can be generated in both their triplet and singlet states, and both states coexist under the conditions of matrix isolation. According to our calculations, the singlet and triplet states of these car-benes are energetically nearly degenerate in the gas phase. Warming of matrices containing pure triplet p-tolyl(trifluoromethyl) carbene from 3 to 25 K leads to an interconversion of up to 20% of the triplet into the singlet state...
August 8, 2017: Journal of the American Chemical Society
Alex T Piet, Jeffrey C Erlich, Charles D Kopec, Carlos D Brody
Two-node attractor networks are flexible models for neural activity during decision making. Depending on the network configuration, these networks can model distinct aspects of decisions including evidence integration, evidence categorization, and decision memory. Here, we use attractor networks to model recent causal perturbations of the frontal orienting fields (FOF) in rat cortex during a perceptual decision-making task (Erlich, Brunton, Duan, Hanks, & Brody, 2015). We focus on a striking feature of the perturbation results...
August 4, 2017: Neural Computation
Ajay Kumar Yagati, Taek Lee, Jeong-Woo Choi
In the present study, we propose a method for bio-nano hybrid formation by coupling a redox metalloprotein, Azurin, with CdSe-ZnS quantum dot for the development of a nanoscale resistive memory device. The covalent interaction between the two nanomaterials enables a strong and effective binding to form an azurin/CdSe-ZnS hybrid, and also enabled better controllability to couple with electrodes to examine the memory function properties. Morphological and optical properties were performed to confirm both hybrid formations and also their individual components...
July 15, 2017: Materials
Zhipeng Wu, Jun Zhu
A metal-insulator-metal structure resistive switching device based on H0.5Z0.5O₂ (HZO) thin film deposited by pulse laser deposition (PLD) has been investigated for resistive random access memory (RRAM) applications. The devices demonstrated bistable and reproducible unipolar resistive switching (RS) behaviors with an extremely high OFF/ON ratio over 5400. The retention property had no degradation at 6 × 10⁴ s. The current-voltage characteristics of the HZO samples showed a Schottky emission conduction in the high voltage region (Vreset < V < Vset), while at the low voltage region (V < Vreset), the ohmic contact and space charge limited conduction (SCLC) are suggested to be responsible for the low and high resistance states, respectively...
March 22, 2017: Materials
Michael C Tackenberg, Carl H Johnson, Terry L Page, Serge Daan
Among the scientific resources that Colin Pittendrigh passed on to his colleagues after his death in 1996 were two unpublished papers. These manuscripts, developed first in the mid-1960s and continually updated and refined through the late 1970s, centered on the development and experimental exploration of a model of circadian entrainment combining aspects of the well-known parametric (continuous) and nonparametric (discrete) models of entrainment. These texts reveal the experimental work surrounding Pittendrigh's determination of the limits of entrainment and the explanation of the bistability phenomenon...
July 1, 2017: Journal of Biological Rhythms
Rakesh Das, Manoranjan Kumar, Shradha Mishra
We introduce a lattice model for active nematic composed of self-propelled apolar particles, study its different ordering states in the density-temperature parameter space, and compare with the corresponding equilibrium model. The active particles interact with their neighbours within the framework of the Lebwohl-Lasher model, and move anisotropically along their orientation to an unoccupied nearest neighbour lattice site. An interplay of the activity, thermal fluctuations and density gives rise distinct states in the system...
August 1, 2017: Scientific Reports
K A Modic, B J Ramshaw, J B Betts, Nicholas P Breznay, James G Analytis, Ross D McDonald, Arkady Shekhter
The complex antiferromagnetic orders observed in the honeycomb iridates are a double-edged sword in the search for a quantum spin-liquid: both attesting that the magnetic interactions provide many of the necessary ingredients, while simultaneously impeding access. Focus has naturally been drawn to the unusual magnetic orders that hint at the underlying spin correlations. However, the study of any particular broken symmetry state generally provides little clue about the possibility of other nearby ground states...
August 1, 2017: Nature Communications
Jing Feng, Wei Xu, Yong Xu, Xiaolong Wang, Jürgen Kurths
The influences of external Lévy noise in CO oxidation on the Ir(111) surfaces are numerically examined. Depending on the control parameters, such as the temperature T  and the CO fraction Y  in the total reactant input gas flux, the reaction exhibits one or two stable stationary states in the absence of noise. Lévy noise is introduced in the reaction by randomly varying the quality of the influx mixture. We then observe a large variety of different types of behaviors depending on the initial CO fraction Y, in particular, the phenomenon of noise-induced shifts of the steady state in the monostable regime is regarded...
July 2017: Chaos
Marcella M Gomez, Murat Arcak
Synthesizing spatial patterns with genetic networks is an ongoing challenge in synthetic biology. A successful demonstration of pattern formation would imply a better understanding of systems in the natural world and advance applications in synthetic biology. In developmental systems, transient patterning may suffice in order to imprint instructions for long-term development. In this paper we show that transient but persistent patterns can emerge from a realizable synthetic gene network based on a toggle switch...
August 1, 2017: ACS Synthetic Biology
Tomokazu Urakawa, Mao Bunya, Osamu Araki
A bistable image induces one of two perceptual alternatives. When the bistable visual image is continuously viewed, the percept of the image alternates from one possible percept to the other. Perceptual alternation was previously reported to be induced by an exogenous perturbation in the bistable image, and this perturbation was theoretically interpreted to cause neural noise, prompting a transition between two stable perceptual states. However, little is known experimentally about the visual processing of exogenously driven perceptual alternation...
August 2017: Cognitive Neurodynamics
Alexander A Green, Jongmin Kim, Duo Ma, Pamela A Silver, James J Collins, Peng Yin
Synthetic biology aims to develop engineering-driven approaches to the programming of cellular functions that could yield transformative technologies. Synthetic gene circuits that combine DNA, protein, and RNA components have demonstrated a range of functions such as bistability, oscillation, feedback, and logic capabilities. However, it remains challenging to scale up these circuits owing to the limited number of designable, orthogonal, high-performance parts, the empirical and often tedious composition rules, and the requirements for substantial resources for encoding and operation...
August 3, 2017: Nature
Matthias Bauer, Johannes Knebel, Matthias Lechner, Peter Pickl, Erwin Frey
Autoinducers are small signaling molecules that mediate intercellular communication in microbial populations and trigger coordinated gene expression via 'quorum sensing'. Elucidating the mechanisms that control autoinducer production is, thus, pertinent to understanding collective microbial behavior, such as virulence and bioluminescence. Recent experiments have shown a heterogeneous promoter activity of autoinducer synthase genes, suggesting that some of the isogenic cells in a population might produce autoinducers, whereas others might not...
July 25, 2017: ELife
Jochen R Brandt, Lubomír Pospíšil, Lucie Bednárová, Rosenildo Correa da Costa, Andrew J P White, Tadashi Mori, Filip Teplý, Matthew J Fuchter
Electrochemical reduction of an azoniahelicene affords a dimer, accompanied by a strong change in the electronic circular dichroism. The fast dimerisation event leads to a >500 mV shift of the oxidation potential, affording a large area of bistability, where the chiroptical signal only depends on the redox history.
July 24, 2017: Chemical Communications: Chem Comm
Satohiro Tajima, Kowa Koida, Chihiro I Tajima, Hideyuki Suzuki, Kazuyuki Aihara, Hidehiko Komatsu
The capacity for flexible sensory-action association in animals has been related to context-dependent attractor dynamics outside the sensory cortices. Here, we report a line of evidence that flexibly modulated attractor dynamics during task switching are already present in the higher visual cortex in macaque monkeys. With a nonlinear decoding approach, we can extract the particular aspect of the neural population response that reflects the task-induced emergence of bistable attractor dynamics in a neural population, which could be obscured by standard unsupervised dimensionality reductions such as PCA...
July 24, 2017: ELife
Jens Kügel, Markus Leisegang, Markus Böhme, Andreas Krönlein, Aimee Sixta, Matthias Bode
Molecular electronics where single molecules perform basic functionalities of digital circuits is a fascinating concept that one day may augment or even replace nowadays semiconductor technologies. The tautomerization of molecules, that is, the bistable functional position of hydrogen protons within an organic frame, has recently been intensively discussed as a potential avenue toward nanoscale switches. It has been shown that tautomerization can be triggered locally or nonlocally, that is, by a scanning tunneling microscope (STM) tip positioned directly above or in close vicinity to the molecule...
July 26, 2017: Nano Letters
Gengwen Tan, Xinping Wang
Since the pioneering work by Thiele and Chichibabin, who synthesized the first diradicals bridged by phenylene and biphenylene groups in 1904 and 1907, respectively, numerous efforts have been devoted to synthesizing stable diradicals during the last few decades, and several strategies have been developed to stabilize these highly reactive diradicals. In this Account, we describe the synthesis and characterization of isolable bis(triarylamine) dications, nitrogen analogues of Thiele's, Chichibabin's, and Müller's hydrocarbons, which represent facilely accessible, stable diradicals by replacing carbinyl centers with isoelectronic aminium centers...
July 21, 2017: Accounts of Chemical Research
Tobias Garling, Yujin Tong, Tamim Darwish, Martin Wolf, R Kramer Campen
Surfaces whose macroscopic properties can be switched by light are potentially useful in a wide variety of applications. One such promising application is electrochemical sensors that can be gated by optically switching the electrode <i>on</i> or <i>off</i>. One way to make such a switchable electrode is by depositing a self-assembled monolayer of bistable, optically switchable molecules onto an electrode surface. Quantitative application of any such sensor requires understanding how changes in interfacial field affect the composition of photostationary states, <i>i...
July 20, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Casey O Diekman, Peter J Thomas, Christopher G Wilson
How sensory information influences the dynamics of rhythm generation varies across systems, and general principles for understanding this aspect of motor control are lacking. Determining the origin of respiratory rhythm generation is challenging because the mechanisms in a central circuit considered in isolation may be different than those in the intact organism. We analyze a closed-loop respiratory control model incorporating a central pattern generator (CPG), the Butera-Rinzel-Smith (BRS) model, together with lung mechanics, oxygen handling, and chemosensory components...
July 19, 2017: Journal of Neurophysiology
Zhan-Qi Cao, Yi-Chuan Wang, Ai-Hua Zou, Gábor London, Qi Zhang, Chuan Gao, Da-Hui Qu
An acid/base responsive amphiphilic [2]rotaxane switch containing a hydrophilic macrocycle component and a hydrophobic terminal bulky group was prepared and characterized. The morphology of the supramolecular assemblies formed by the rotaxanes could be switched between spherical vesicles and worm-like micelles using acid/base stimuli, as confirmed by transmission electron microscopy (TEM).
July 19, 2017: Chemical Communications: Chem Comm
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