scholarly journals Geometrical model explains multiple preferred escape trajectories of fish

2020 ◽  
Author(s):  
Yuuki Kawabata ◽  
Hideyuki Akada ◽  
Ken-ichiro Shimatani ◽  
Gregory N. Nishihara ◽  
Hibiki Kimura ◽  
...  
Keyword(s):  
Local Maximum ◽  
Geometrical Model ◽  
Time Difference ◽  
Entry Point ◽  
Safety Zone ◽  
Similar Extent ◽  
Response Data ◽  
Escape Trajectories ◽  
High Level ◽  
Ambush Predators

AbstractTo evade predators, many prey perform rapid escape movements. The resulting escape trajectory (ET) – measured as the angle of escape direction relative to the predator’s approach path – plays a major role in avoiding predation. Previous geometrical models predict a single ET; however, many animals (fish and other animal taxa) show highly variable ETs with multiple preferred directions. Although such a high ET variability may confer unpredictability, preventing predators from adopting counter-strategies, the reasons why animals prefer specific multiple ETs remain unclear. Here, we constructed a novel geometrical model in which Tdiff (the time difference between the prey entering the safety zone and the predator reaching that entry point) is expected to be maximized. We tested this prediction by analyzing the escape responses of Pagrus major attacked by a dummy predator. At each initial body orientation of the prey relative to the predator, our model predicts a multimodal ET with an optimal ET at the maximum Tdiff (Tdiff,1) and a suboptimal ET at a second local maximum of Tdiff (Tdiff,2). Our experiments show that when Tdiff, 1–Tdiff, 2 is negligible, the prey uses optimal or suboptimal ETs to a similar extent, in line with the idea of unpredictability. The experimentally observed ET distribution is consistent with the model, showing two large peaks at 110–130° and 170–180° away from the predator. Because various animal taxa show multiple preferred ETs similar to those observed here, this behavioral phenotype may result from convergent evolution that combines maximal Tdiff with a high level of unpredictability.Significance StatementAnimals from many taxa escape from suddenly approaching threats, such as ambush predators, by using multiple preferred escape trajectories. However, the reason why these multiple preferred escape trajectories are used is still unknown. By fitting a newly constructed model to the empirical escape response data, we show that the seemingly complex multiple preferred escape trajectories can arise from a simple geometrical rule which maximizes the time difference between when the prey enters the safety zone and when the predator reaches that entry point. Our results open new avenues of investigation for understanding how animals choose their escape trajectories from behavioral and neurosensory perspectives.

Robust Position Controller Design for Linear Servo Units Used in Noncircular Machining

2004 ◽  
Vol 471-472 ◽  
pp. 755-759
Author(s):  
S.T. Huang ◽  
Jing Feng Zhi ◽  
Hao Bo Cheng ◽  
W. Zuo
Keyword(s):  
Controller Design ◽  
Feedforward Control ◽  
Ball Screw ◽  
Tracking Accuracy ◽  
Response Data ◽  
Noncircular Machining ◽  
Driven System ◽  
Position Controller ◽  
Simple Error ◽  
High Level

This paper presents the design and implementation of a robust motion control structure for linear servo units used in noncircular machining. Compared with ball/screw driven system, the controller of the linear motor driven system must provide a high level of disturbance rejection performance, as the system is more sensitive to force disturbances and parameter variations. Thus, in this paper, a robust feedback controller based on disturbance observer is applied to enhance the stiffness and robustness. A magnitude and phase regulating control scheme (MPRC) is proposed to improve the system tracking accuracy, and a simple error feedforward compensator (EFC) further reduces the feedforward control error that result from inaccurate frequency response data. The effectiveness of the proposed controller is demonstrated by experiments.

DEVELOPING THE METHODS FOR EVALUATION OF ECONOMIC EFFICIENCY OF ECOLOGICAL INVESTMENTS

Economical ◽  
2019 ◽  
Vol 2 (2(21)) ◽  
pp. 151-158
Author(s):  
Olga Popova ◽  
Keyword(s):  
Economic Evaluation ◽  
Discount Rate ◽  
Critical Points ◽  
Modern World ◽  
Investment Efficiency ◽  
Safety Zone ◽  
Dynamic Methods ◽  
The Interest Rate ◽  
High Level ◽  
Investment Process

The article describes the modern world experience in the formation and development of the system of economic evaluation of environmental investments. Approaches to the formation of the discount rate using dynamic methods of evaluating the effectiveness of investments are analyzed. An analysis of world experience in the economic evaluation of environmental investments. It is established that the methods of economic evaluation of environmental investments require adjustment of the main investment parameters - the amount of investment payments, the duration of the planned horizon, the discount rate - taking into account the specifics of such investments. The article identifies a high level of environmental risk and higher amounts of invested capital as specific features of environmental investments. This primarily applies to the methodology of economic evaluation of environmental investments, which are characterized by an increased level of risk, higher cost of capital involved in contrast to traditional investments. It is proposed to consider the conditions for the formation of critical points in the interest rate on the example of an investment designed for five years. The choice of such a planned project implementation horizon is due to the fact that with an odd number of years there is always at least one critical point and under certain conditions, which will be discussed below, there is a possibility of new critical points that expand investment efficiency. It is shown that if the project is designed for an even number of years, the existence of one such point is not always possible. The study confirms that with a certain change in investment parameters there is an expansion or contraction of the safety zone when changing one or more parameters of environmental investment. implementation will be economically feasible for all participants in the investment process.

The Use of Artificial Neural Networks for Objective Determination of Hearing Threshold Using the Auditory Brainstem Response

2011 ◽  
pp. 195-216
Author(s):  
Robert T. Davey ◽  
Paul J. McCullagh ◽  
H. Gerry McAllister ◽  
H. Glen Houston
Keyword(s):  
Auditory Brainstem Response ◽  
Classification Accuracy ◽  
Hearing Threshold ◽  
Auditory Brainstem ◽  
Time Frequency ◽  
Response Data ◽  
Brainstem Response ◽  
Stage Process ◽  
High Level ◽  
Age Range

We have analyzed high and low level auditory brainstem response data (550 waveforms over a large age range; 126 were repeated sessions used in correlation analysis), by extracting time, frequency, and phase features and using these as inputs to ANN and decision tree classifiers. A two stage process is used. For responses with a high poststimulus to prestimulus power ratio indicative of high level responses, a classification accuracy of98% has been achieved. These responses are easily classified by the human expert. For lower level responses appropriate to hearing threshold, additional features from time, frequency, and phase have been used for classification, providing accuracies between 65% and 82%. These used a dataset with repeated recordings so that correlation could be employed. To increase classification accuracy, it may be necessary to combine the relevant features in a hybrid model.

Nanotechnological Medical Devices and Nanopharmaceuticals: The European Regulatory Framework and Research Needs

2007 ◽  
Vol 7 (12) ◽  
pp. 4618-4625 ◽  
Author(s):  
D. G. Rickerby
Keyword(s):  
Medical Devices ◽  
Scientific Evidence ◽  
Regulatory Framework ◽  
The Body ◽  
Regulatory Regime ◽  
Response Data ◽  
Stage Of Development ◽  
European Regulatory ◽  
Living Organisms ◽  
High Level

The European regulatory framework is examined in relation to nanotechnology based medical devices and medicinal products. Medical applications of nanotechnology will have to comply with the requirement for a high level of public health, safety, consumer, and environmental protection. An evaluation of the possible health or environmental risks of nanoparticles must therefore be carried out and it is important to ensure that particle size and chemistry are taken into account when investigating possible adverse effects. Further research is needed on the toxicological and ecotoxicological properties of nanoparticles, their uptake in the body, accumulation in tissues and organs, transport characteristics, exposure and dose-response data, and their distribution and persistence in the environment. The existing regulations appear adequate to manage the risks of nanotechnology at its current stage of development but continuous review of the regulatory regime will be needed to determine whether it is sufficient to protect human health and the environment. Modification of the legislation may prove necessary as new scientific evidence emerges regarding the effects of nanoparticles on living organisms and in the ecosystems.

scholarly journals Modelling natural and artificial hands with synergies

2011 ◽  
Vol 366 (1581) ◽  
pp. 3153-3161 ◽  
Author(s):  
Antonio Bicchi ◽  
Marco Gabiccini ◽  
Marco Santello
Keyword(s):  
Degrees Of Freedom ◽  
Sensory Information ◽  
Geometrical Model ◽  
Force Distribution ◽  
Tactile Sensors ◽  
Frequent Use ◽  
Fast Processing ◽  
High Level ◽  
Dual Domain ◽  
And Control

We report on recent work in modelling the process of grasping and active touch by natural and artificial hands. Starting from observations made in human hands about the correlation of degrees of freedom in patterns of more frequent use (postural synergies), we consider the implications of a geometrical model accounting for such data, which is applicable to the pre-grasping phase occurring when shaping the hand before actual contact with the grasped object. To extend applicability of the synergy model to study force distribution in the actual grasp, we introduce a modified model including the mechanical compliance of the hand's musculotendinous system. Numerical results obtained by this model indicate that the same principal synergies observed from pre-grasp postural data are also fundamental in achieving proper grasp force distribution. To illustrate the concept of synergies in the dual domain of haptic sensing, we provide a review of models of how the complexity and heterogeneity of sensory information from touch can be harnessed in simplified, tractable abstractions. These abstractions are amenable to fast processing to enable quick reflexes as well as elaboration of high-level percepts. Applications of the synergy model to the design and control of artificial hands and tactile sensors are illustrated.

scholarly journals THE RELATIONSHIP BETWEEN ADMINISTRATIVE FACTORS AND EFFECTIVENESS OF ST-SEGMENT ELEVATION MYOCARDIAL INFARCTION REFERRAL SYSTEM AMONG THAI HOSPITALS

2021 ◽  
pp. 15
Author(s):  
Keyword(s):  
Heart Disease ◽  
Target Population ◽  
Referral System ◽  
St Segment Elevation ◽  
Response Data ◽  
Financial Factor ◽  
Management Personnel ◽  
St Segment ◽  
High Level ◽  
The Relationship

Background: This descriptive study aimed to study the relationship between administrative factors and the effectiveness of the referral system of patients with acute ischemic heart disease in Thai hospitals. Materials and methods: The target population was 1,180 hospitals that serving heart disease in Thailand. Data were collected by using a questionnaire. A total of 1,022 response data were obtained. Administrative factors were analyzed using descriptive statistics, and the relationship was analyzed using multiple regression analysis (MRA) methods. Results: The study showed that the administrative factors which consisted of personnel, finance, supporting, and management factors had overall average readiness at a high level (x̄ = 3.34, S.D. = 0.27). Except budget sufficiency was at a low level (x̄ = 2.43, S.D. = 0.43). All factors were related to the mortality rate significantly, as follows: management factor (Adjusted R2 = 0.433), personnel factor (Adjusted R2 = 0.231), supporting factor (Adjusted R2 = 0.092) and financial factor (Adjusted R2 = 0.035). All factors were also significantly related to the timely cardiac catheterization rate, as follows: management factor (Adjusted R2 = 0.442), personnel factor (Adjusted R2 = 0.244), supporting factor (Adjusted R2 = 0.212) and financial factor (Adjusted R2 = 0.091). Conclusion: Thai Ministry of Public Health should provide adequate support for administrative factors, especially in terms of management, personnel, supporting factors, and budget sufficiency.

Oceanographic and Motion Response Statistics for the Operation of a Weathervaning LNG FPSO

2003 ◽  
Author(s):  
Kevin Ewans ◽  
Clemens van der Valk ◽  
Christopher Shaw ◽  
Joost den Haan ◽  
Peter Tromans ◽  
...  
Keyword(s):  
Mooring Line ◽  
Current Profile ◽  
Mooring Lines ◽  
Motion Response ◽  
Response Data ◽  
Oceanographic Data ◽  
One Year ◽  
Vessel Motion ◽  
High Level ◽  
Inertial Currents

An oceanographic database is used to estimate the operability of a weathervaning LNG FPSO (FLNG) in multidirectional seas with swells. The oceanographic data consist of directional wave data, current profile measurements, and a wind dataset. Response functions are used to convert the oceanographic data into an equivalent dataset of vessel motion response parameters and turret mooring line tensions. The resulting response data have enabled operational type statistics to be computed, as well as the environmental conditions that induce responses with a one-year return period. In addition to the analysis of the responses of the FLNG alone, the method has been applied to a system where a LNG shuttle carrier is moored alongside the FLNG for offloading of the products. In this case, important responses are the combined roll and pitch of the two vessels and tension in the mooring lines between the shuttle carrier and the FLNG. The same method can be applied for a stern-to-bow offloading system, where the shuttle carrier is moored with a hawser or soft yoke. The diversity of the directionality of the oceanographic variables makes this a particularly interesting exercise. The analysis included significant inertial currents, a high level of background swell and frequent local-wind seas that act at an angle to the prevailing swell direction. A method for separating a sea state into a sea and swell component has been derived and is reported, along with a programme for visualising the oceanographic conditions together with the induced responses corresponding to the existing conditions.

scholarly journals Generation of TD50 values for carcinogenicity study data

2019 ◽  
Vol 8 (5) ◽  
pp. 696-703 ◽  
Author(s):  
Andrew Thresher ◽  
John Paul Gosling ◽  
Richard Williams
Keyword(s):  
Study Data ◽  
Carcinogenic Potency ◽  
Inappropriate Use ◽  
Chemical Risk Assessment ◽  
Carcinogenicity Study ◽  
Response Data ◽  
Key Factor ◽  
Assessment Measures ◽  
High Level

Abstract Carcinogenic potency is a key factor in the understanding of chemical risk assessment. Measures of carcinogenic potency, for example TD50, are instrumental in the determination of metrics such as the threshold of toxicological concern (TTC), acceptable intake (AI) and permitted daily exposure (PDE), which in turn impact on human exposure. The Carcinogenic Potency Data Base (CPDB) has provided a source of study information, complete with calculated TD50 values. However, this is no longer actively updated. An understanding of carcinogenic potency, which can be derived from dose–response data, can be used as part of human risk assessments to generate safety thresholds under which cancer risk is judged to be minimal. The aim of this paper is to produce a transparent methodology for calculating TD50 values from experimental data in a manner consistent with the CPDB. This was then applied across the same data as used in the CPDB and analysis done on the correlation with the CPDB TD50 values. While the two sets of values showed a high level of correlation overall, there were some significant discrepancies. These were predominantly due to a lack of clarity in the CPDB methodology and inappropriate use of a linear model in TD50 calculation where the data was not suitable for such an approach.

scholarly journals Data variability in standardised cell culture experiments

2021 ◽  
Author(s):  
Ian G. Reddin ◽  
Tim Fenton ◽  
Mark N. Wass ◽  
Martin Michaelis
Keyword(s):  
Cell Line ◽  
Response Data ◽  
Data Variability ◽  
Anti Cancer ◽  
Cell Line Panel ◽  
Approved Drugs ◽  
High Level ◽  
Fda Approved Drugs ◽  
Very High ◽  
Intrinsic Feature

AbstractDespite much debate about a perceived ‘reproducibility crisis’ in the life sciences, it remains unclear what level of replicability is technically possible [1,2]. Here, we analysed the variation among drug response data of the NCI60 project, which for decades has tested anti-cancer agents in a 60-cell line panel following a standardised protocol [3]. In total, 2.8 million compound/cell line experiments are available in the NCI60 resource CellMiner [4]. The largest fold change between the lowest and highest GI50 (concentration that reduces cell viability by 50%) in a compound/cell line combination was 3.16 x 1010. All compound/cell line combinations with >100 experiments displayed maximum GI50 fold changes >5, 99.7% maximum fold changes >10, 87.3% maximum fold changes >100, and 70.5% maximum fold changes >1000. FDA-approved drugs and experimental agents displayed similar variation. The variability remained very high after removal of outliers and among experiments performed in the same month. Hence, our analysis shows that high variability is an intrinsic feature of experimentation in biological systems, even among highly standardised experiments in a world-leading research environment. Thus, a narrow focus on experiment standardisation does not ensure a high level of replicability on its own.

Transcription factor/DNA interactions visualized by electron spectroscopic imaging

1992 ◽  
Vol 50 (1) ◽  
pp. 450-451
Author(s):  
David P. Bazett-Jones ◽  
Mark L. Brown
Keyword(s):  
Transcription Factor ◽  
Dna Sequences ◽  
Transcription Initiation ◽  
Molecular Mechanisms ◽  
Phosphorus Content ◽  
Spectroscopic Imaging ◽  
Electron Spectroscopic Imaging ◽  
Dna Backbone ◽  
Two Parameters ◽  
High Level

A multisubunit RNA polymerase enzyme is ultimately responsible for transcription initiation and elongation of RNA, but recognition of the proper start site by the enzyme is regulated by general, temporal and gene-specific trans-factors interacting at promoter and enhancer DNA sequences. To understand the molecular mechanisms which precisely regulate the transcription initiation event, it is crucial to elucidate the structure of the transcription factor/DNA complexes involved. Electron spectroscopic imaging (ESI) provides the opportunity to visualize individual DNA molecules. Enhancement of DNA contrast with ESI is accomplished by imaging with electrons that have interacted with inner shell electrons of phosphorus in the DNA backbone. Phosphorus detection at this intermediately high level of resolution (≈lnm) permits selective imaging of the DNA, to determine whether the protein factors compact, bend or wrap the DNA. Simultaneously, mass analysis and phosphorus content can be measured quantitatively, using adjacent DNA or tobacco mosaic virus (TMV) as mass and phosphorus standards. These two parameters provide stoichiometric information relating the ratios of protein:DNA content.

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