53 research outputs found
Modelling Temperature Variation of Mushroom Growing Hall Using Artificial Neural Networks
The recent developments of computer and electronic systems have made the use
of intelligent systems for the automation of agricultural industries. In this
study, the temperature variation of the mushroom growing room was modeled by
multi-layered perceptron and radial basis function networks based on
independent parameters including ambient temperature, water temperature, fresh
air and circulation air dampers, and water tap. According to the obtained
results from the networks, the best network for MLP was in the second
repetition with 12 neurons in the hidden layer and in 20 neurons in the hidden
layer for radial basis function network. The obtained results from comparative
parameters for two networks showed the highest correlation coefficient (0.966),
the lowest root mean square error (RMSE) (0.787) and the lowest mean absolute
error (MAE) (0.02746) for radial basis function. Therefore, the neural network
with radial basis function was selected as a predictor of the behavior of the
system for the temperature of mushroom growing halls controlling system
Holographic Entanglement Entropy in Lovelock Gravities
We study entanglement entropies of simply connected surfaces in field
theories dual to Lovelock gravities. We consider Gauss-Bonnet and cubic
Lovelock gravities in detail. In the conformal case the logarithmic terms in
the entanglement entropy are governed by the conformal anomalies of the CFT; we
verify that the holographic calculations are consistent with this property. We
also compute the holographic entanglement entropy of a slab in the Gauss-Bonnet
examples dual to relativistic and non-relativistic CFTs and discuss its
properties. Finally, we discuss features of the entanglement entropy in the
backgrounds dual to renormalization group flows between fixed points and
comment on the implications for a possible c-theorem in four spacetime
dimensions.Comment: harvmac, 30 pages, 1 figure, References added, typos correcte
Homozygous Missense Variants in NTNG2, Encoding a Presynaptic Netrin-G2 Adhesion Protein, Lead to a Distinct Neurodevelopmental Disorder.
NTNG2 encodes netrin-G2, a membrane-anchored protein implicated in the molecular organization of neuronal circuitry and synaptic organization and diversification in vertebrates. In this study, through a combination of exome sequencing and autozygosity mapping, we have identified 16 individuals (from seven unrelated families) with ultra-rare homozygous missense variants in NTNG2; these individuals present with shared features of a neurodevelopmental disorder consisting of global developmental delay, severe to profound intellectual disability, muscle weakness and abnormal tone, autistic features, behavioral abnormalities, and variable dysmorphisms. The variants disrupt highly conserved residues across the protein. Functional experiments, including in silico analysis of the protein structure, in vitro assessment of cell surface expression, and in vitro knockdown, revealed potential mechanisms of pathogenicity of the variants, including loss of protein function and decreased neurite outgrowth. Our data indicate that appropriate expression of NTNG2 plays an important role in neurotypical development
Towards a derivation of holographic entanglement entropy
We provide a derivation of holographic entanglement entropy for spherical
entangling surfaces. Our construction relies on conformally mapping the
boundary CFT to a hyperbolic geometry and observing that the vacuum state is
mapped to a thermal state in the latter geometry. Hence the conformal
transformation maps the entanglement entropy to the thermodynamic entropy of
this thermal state. The AdS/CFT dictionary allows us to calculate this
thermodynamic entropy as the horizon entropy of a certain topological black
hole. In even dimensions, we also demonstrate that the universal contribution
to the entanglement entropy is given by A-type trace anomaly for any CFT,
without reference to holography.Comment: 42 pages, 2 figures, few new ref's and comments adde
A biophysical model of dynamic balancing of excitation and inhibition in fast oscillatory large-scale networks
Over long timescales, neuronal dynamics can be robust to quite large perturbations, such as changes in white matter connectivity and grey matter structure through processes including learning, aging, development and certain disease processes. One possible explanation is that robust dynamics are facilitated by homeostatic mechanisms that can dynamically rebalance brain networks. In this study, we simulate a cortical brain network using the Wilson-Cowan neural mass model with conduction delays and noise, and use inhibitory synaptic plasticity (ISP) to dynamically achieve a spatially local balance between excitation and inhibition. Using MEG data from 55 subjects we find that ISP enables us to simultaneously achieve high correlation with multiple measures of functional connectivity, including amplitude envelope correlation and phase locking. Further, we find that ISP successfully achieves local E/I balance, and can consistently predict the functional connectivity computed from real MEG data, for a much wider range of model parameters than is possible with a model without ISP
Frequency-Domain vs Continuous-Wave Near-Infrared Spectroscopy devices:A comparison of clinically viable monitors in controlled hypoxia
Controlled Crosslinking Is a Tool To Precisely Modulate the Nanomechanical and Nanotribological Properties of Polymer Brushes
Covalent crosslinking of weak polyelectrolyte brushes widens the tuning potential for their swelling, nanomechanical, and nanotribological properties, which can be simultaneously adjusted by varying the crosslinker content and the pH of the surroundings. We demonstrate that this is especially valid for poly(hydroxyethyl methacrylate) (PHEMA) brushes and brush hydrogels, and their ionizable, succinate-modified derivatives (PHEMA-SA), covalently crosslinked with different amounts of di(ethylene glycol) dimethacrylate (DEGDMA) during surface-initiated atom transfer radical polymerization (SI-ATRP). Atomic force microscopy (AFM) methods highlight how pristine PHEMA films are stiff and display high coefficients of friction in water. Their succinate derivatives swell profusely in aqueous, media. Under acidic conditions they are neutral, compliant, and lubricious, with apparent Young's moduli (E*) lying between 10 and 30 kPa. Their contact mechanical behavior can be described by either the Johnson-Kendall-Roberts (JKR) or the Derjaguin-Muller-Toporov (DMT) model, depending on crosslinker content. In contrast, under basic conditions, brushes and brush hydrogels become charged, expand, and present a rigid, electrostatic barrier toward the AFM probe. Friction is extremely low at relatively low applied loads, whereas it increases at higher loads, to an extent that is regulated by the number of crosslinks within the films
Engineering Lubricious, Biopassive Polymer Brushes by Surface-Initiated, Controlled Radical Polymerization
Surface-initiated controlled radical polymerization enables the fabrication of biopassive polymer brushes with interfacial, physicochemical properties that can be independently varied across a single substrate. Poly[(oligoethylene glycol) methacrylate] (POEGMA) brushes were synthesized by surface initiated atom transfer radical polymerization (SI-ATRP), locally varying the exposure of initiator-functionalized surfaces to the polymerization solution to yield POEGMA brush thickness gradients. A combination of variable-angle spectroscopic ellipsometry (VASE) and atomic force microscopy (AFM) demonstrated that brush swelling, grafting density, nano mechanical properties, and biopassivity towards protein adsorption all remained constant within a thickness range between 20 and 90 nm. However, the nanotribological properties of POEGMA brushes, investigated by lateral force microscopy (LFM), were found to vary progressively along the gradient, thinner brushes showing significantly lower friction than thicker and more viscoelastic grafts. The independent variation of lubricity across a biopassive brush gradient shows how SI-ATRP can be used to tailor surfaces destined for applications involving both contact with biological media and exposure to shear stresses, as is the case for tissue-replacement implants and scaffolds for tissue engineering
Crosslinking Polymer Brushes with Ethylene Glycol-Containing Segments: Influence on Physicochemical and Antifouling Properties
The introduction of different types and concentrations of crosslinks within poly(hydroxyethyl methacrylate) (PHEMA) brushes influences their interfacial, physicochemical properties, ultimately governing their adsorption of proteins. PHEMA brushes and brush-hydrogels were synthesized by surface-initiated, atom-transfer radical polymerization (SI-ATRP) from HEMA, with and without the addition of di(ethylene glycol) dimethacrylate (DEGDMA) or tetra (ethylene glycol) dimethacrylate (TEGDMA) as crosslinkers. Linear (pure PHEMA) brushes show high hydration and low modulus and additionally provide an efficient barrier against nonspecific protein adsorption. In contrast, brush-hydrogels are stiffer and less hydrated, and the presence of crosslinks affects the entropy-driven, conformational barrier that hinders the surface interaction of biomolecules with brushes. This leads to the physisorption of proteins at low concentrations of short crosslinks. At higher contents of DEGDMA or in the presence of longer TEGDMA-based crosslinks, brush-hydrogels recover their antifouling properties due to the increase in interfacial water association by the higher concentration of ethylene glycol (EG) units
Fabrication and Interfacial Properties of Polymer Brush Gradients by Surface-Initiated Cu(0)-Mediated Controlled Radical Polymerization
Surface-initiated Cu(0)-mediated controlled radical polymerization (SiCuCRP) can be successfully applied to fabricate poly[(oligoethylene glycol)methyl ether methacrylate] (POEGMA) brushes in one pot, presenting a grafting-density gradient across the surface. This is achieved by continuously varying the distance (d) between a copper plate, used as a source of Cu species, and the initiator-functionalized substrate. X-ray photoelectron spectroscopy (XPS) analysis of monolayers of Culselective ligands demonstrates that a higher concentration of activator species diffuses to the initiating substrate in areas closer to the copper plate, a progressive decrease in activator concentration being observed upon increasing the distance between the two surfaces. As confirmed by the SI-CuCRP kinetics measured at different positions along the gradient, radical-termination reactions between propagating chains limit the grafting density of POEGMA grafts where the diffusion of activators is favored (i.e., at d 0). This effect decreases with increasing d, ultimately yielding a gradual variation of POEGMA grafting density across the substrate. We have investigated the influence of grafting-density variation across the gradient on the swelling of POEGMA brushes as well as on their nanomechanical and nanotribological properties, measured by a combination of variable angle spectroscopic ellipsometry (VASE), colloidal-probe atomic force microscopy (CP-AFM), and lateral force microscopy (LFM). The results of these tests highlight how loosely grafted POEGMA chains incorporating a substantial amount of water can be significantly deformed by a shearing AFM probe, exhibit relatively high friction, and generate friction-vs-load (F-f-L) profiles that follow a sublinear trend described by a Johnson Kendall-Roberts (JKR) model-typical of deformable films of high surface energy. In contrast, more densely packed POEGMA brushes incorporate less solvent and display very low friction, with F-f-L data following a linear progression according to Amontons' law
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