1,263 research outputs found
Fish assemblages associated with three types of artificial reefs: density of assemblages and possible impacts on adjacent fish abundance
We evaluated the effectiveness of wooden artificial reefs (ARs) as fish habitat. Three types of ARs, made of cedar logs, broadleaf tree logs, and PVC pipes, respectively,
were deployed in triplicate at 8-m depth off Maizuru, Kyoto Prefecture, Sea of Japan, in May 2004. Fish assemblages associated with each of the nine ARs were observed by using
SCUBA twice a month for four years. Fish assemblages in the adjacent habitat were also monitored for two years before and four years after reef deployment. In the surveyed areas
(ca. 10 m2) associated with each of the cedar, broadleaf, and PVC ARs, the average number of fish species was 4.14, 3.49, and 3.00, and the average number of individuals was 40.7, 27.9, and 20.3, respectively. The estimated biomass was also more greater when associated with the cedar ARs than with other ARs. Visual censuses of the habitat adjacent to the ARs revealed that the number of fish species and the density of individuals were not affected by the deployment of the ARs. Our results support the superiority of cedar as an AR material and indicate that deployment of wooden ARs causes no reduction of fish abundance in adjacent natural reefs
Chemical turbulence equivalent to Nikolavskii turbulence
We find evidence that a certain class of reaction-diffusion systems can
exhibit chemical turbulence equivalent to Nikolaevskii turbulence. The
distinctive characteristic of this type of turbulence is that it results from
the interaction of weakly stable long-wavelength modes and unstable
short-wavelength modes. We indirectly study this class of reaction-diffusion
systems by considering an extended complex Ginzburg-Landau (CGL) equation that
was previously derived from this class of reaction-diffusion systems. First, we
show numerically that the power spectrum of this CGL equation in a particular
regime is qualitatively quite similar to that of the Nikolaevskii equation.
Then, we demonstrate that the Nikolaevskii equation can in fact be obtained
from this CGL equation through a phase reduction procedure applied in the
neighborhood of a codimension-two Turing--Benjamin-Feir point.Comment: 10 pages, 3 figure
Co-Training Realized Volatility Prediction Model with Neural Distributional Transformation
This paper shows a novel machine learning model for realized volatility (RV)
prediction using a normalizing flow, an invertible neural network. Since RV is
known to be skewed and have a fat tail, previous methods transform RV into
values that follow a latent distribution with an explicit shape and then apply
a prediction model. However, knowing that shape is non-trivial, and the
transformation result influences the prediction model. This paper proposes to
jointly train the transformation and the prediction model. The training process
follows a maximum-likelihood objective function that is derived from the
assumption that the prediction residuals on the transformed RV time series are
homogeneously Gaussian. The objective function is further approximated using an
expectation-maximum algorithm. On a dataset of 100 stocks, our method
significantly outperforms other methods using analytical or naive
neural-network transformations.Comment: Accepted at ICAIF'2
iplot: web-first visualisation platform for multidimensional data
iplot is an HTML5-based system for interactive exploration of data and
machine learning models. A key aspect is interaction, not only for the
interactive plots but also between plots. Even though iplot is not
restricted to any single application domain, we have developed and tested it
with domain experts in quantum chemistry to study molecular interactions and
regression models. iplot can be run both locally and online in a web
browser (keeping the data local). The plots and data can also easily be
exported and shared. A modular structure also makes iplot optimal for
developing machine learning and new interaction methods.Comment: 5 pages, 1 figure, accepted to the demo track of ECML PKDD 2023,
https://github.com/edahelsinki/xiplo
Cell Shape and Forces in Elastic and Structured Environments: From Single Cells to Organoids
With the advent of mechanobiology, cell shape and forces have emerged as essential elements of cell behavior and fate, in addition to biochemical factors such as growth factors. Cell shape and forces are intrinsically linked to the physical properties of the environment. Extracellular stiffness guides migration of single cells and collectives as well as differentiation and developmental processes. In confined environments, cell division patterns are altered, cell death or extrusion might be initiated, and other modes of cell migration become possible. Tools from materials science such as adhesive micropatterning of soft elastic substrates or direct laser writing of 3D scaffolds have been established to control and quantify cell shape and forces in structured environments. Herein, a review is given on recent experimental and modeling advances in this field, which currently moves from single cells to cell collectives and tissue. A very exciting avenue is the combination of organoids with structured environments, because this will allow one to achieve organotypic function in a controlled setting well suited for long-term and high-throughput culture
Robustness of oscillatory behavior in correlated networks
Understanding network robustness against failures of network units is useful for preventing large-scale breakdowns and damages in real-world networked systems. The tolerance of networked systems whose functions are maintained by collective dynamical behavior of the network units has recently been analyzed in the framework called dynamical robustness of complex networks. The effect of network structure on the dynamical robustness has been examined with various types of network topology, but the role of network assortativity, or degree–degree correlations, is still unclear. Here we study the dynamical robustness of correlated (assortative and disassortative) networks consisting of diffusively coupled oscillators. Numerical analyses for the correlated networks with Poisson and power-law degree distributions show that network assortativity enhances the dynamical robustness of the oscillator networks but the impact of network disassortativity depends on the detailed network connectivity. Furthermore, we theoretically analyze the dynamical robustness of correlated bimodal networks with two-peak degree distributions and show the positive impact of the network assortativity
Okaramine insecticidal alkaloids show similar activity on both exon 3c and exon 3b variants of glutamate-gated chloride channels of the larval silkworm, Bombyx mori
The okaramine indole alkaloids were recently shown to be more selective than ivermectin in activating the glutamate-gated chloride channels of the silkworm larvae of Bombyx mori (BmGluCls). Those studies were carried out using the exon 3b variant as a representative of BmGluCls. However, it remains unknown whether okaramines are similarly effective on other silkworm GluCl variants and whether they share the same binding site as ivermectin on GluCls. To begin to address these questions, we examined the potency of four okaramines on the exon 3c variant of BmGluCls by two-electrode voltage clamp voltage recordings of glutamate-induced chloride currents. The potency of okaramines in activating the exon 3c BmGluCl agreed well with findings on the exon 3b BmGluCl and insecticidal potency. Okaramine B (10μM) reduced the maximum binding (Bmax) but not the dissociation constant (KD) of [(3)H]ivermectin in studies on plasma membrane fractions of HEK293 cells expressing the exon 3c variant. These findings indicate that activation of GluCls is important in the insecticidal actions of okaramines
Feasibility Investigation for Online Elemental Monitoring of Iron and Steel Manufacturing Processes using Laser-Induced Breakdown Spectroscopy
The metallurgical industries are very important for social development. In order to improve the metallurgical techniques and quality of products, the real-time analysis and monitoring of iron and steel manufacturing processes are very significant. Laser-induced breakdown spectroscopy (LIBS) has been studied and applied for the contents measurement of iron and steel. In this paper, the remote open-path LIBS measurement was studied under different sample temperature, lens to target distance (LTD), sample angle conditions to clarify its online measurement features. The 3D profile measurement system of parallel laser beam fringes projection was also developed to measure the sample profile at different sample temperature. The measurement results demonstrated the robustness of remote open-path LIBS system and 3D profile measurement system. However, the correction is necessary to enhance the detection ability of LIBS online measurement. In order to improve the precision and accuracy of real-time elemental measurement, an innovative co-axial laser beam measurement system combining LIBS and 3D profile techniques is proposed to automatically adjust the focus unit and measure the sample components. The further study of this promising method will be developed for online application of iron and steel manufacturing processes
Rossby wave instability in locally isothermal and polytropic disks: three-dimensional linear calculations
Numerical calculations of the linear Rossby wave instability (RWI) in global
three-dimensional (3D) disks are presented. The linearized fluid equations are
solved for vertically stratified, radially structured disks with either a
locally isothermal or polytropic equation of state, by decomposing the vertical
dependence of the perturbed hydrodynamic quantities into Hermite and Gegenbauer
polynomials, respectively. It is confirmed that the RWI operates in 3D. For
perturbations with vertical dependence assumed above, there is little
difference in growth rates between 3D and two-dimensional (2D) calculations.
Comparison between 2D and 3D solutions of this type suggest the RWI is
predominantly a 2D instability and that three-dimensional effects, such as
vertical motion, to be interpreted as a perturbative consequence of the
dominant 2D flow. The vertical flow around co-rotation, where vortex-formation
is expected, is examined. In locally isothermal disks the expected vortex
center remains in approximate vertical hydrostatic equilibrium. For polytropic
disks the vortex center has positive vertical velocity, whose magnitude
increases with decreasing polytropic index .Comment: 17 pages, 21 figures, Accepted by Ap
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