Spatio-Temporal Variation in Length-Weight Relationships and Condition of the Ribbonfish Trichiurus lepturus (Linnaeus, 1758): Implications for Fisheries Management

Knowledge of length-weight relationships for commercially exploited fish is an important tool for assessing and managing of fish stocks. However, analyses of length-weight relationship fisheries data typically do not consider the inherent differences in length-weight relationships for fish caught from different habitats, seasons, or years, and this can affect the utility of these data for developing condition indices or calculating fisheries biomass. Here, we investigated length-weight relationships for ribbonfish Trichiurus lepturus in the waters of the Arabian Sea off Oman collected during three periods (2001-02, 2007-08, and 2014-15) and showed that a multivariate modelling approach that considers the areas and seasons in which ribbonfish were caught improved estimation of length-weight relationships. We used the outputs of these models to explore spatio-temporal variations in condition indices and relative weights among ribbonfish, revealing fish of 85-125 cm were in the best overall condition. We also found that condition differed according to where and when fish were caught, with condition lowest during spring and pre-south-west monsoon periods and highest during and after the south-west monsoons. We interpret these differences to be a consequence of variability in temperature and food availability. Based on our findings, we suggest fishing during seasons that have the lowest impact on fish condition and which are commercially most viable; such fishery management would enhance fisheries conservation and economic revenue in the region

On the Inverse Problem of Binocular 3D Motion Perception

It is shown that existing processing schemes of 3D motion perception such as interocular velocity difference, changing disparity over time, as well as joint encoding of motion and disparity, do not offer a general solution to the inverse optics problem of local binocular 3D motion. Instead we suggest that local velocity constraints in combination with binocular disparity and other depth cues provide a more flexible framework for the solution of the inverse problem. In the context of the aperture problem we derive predictions from two plausible default strategies: (1) the vector normal prefers slow motion in 3D whereas (2) the cyclopean average is based on slow motion in 2D. Predicting perceived motion directions for ambiguous line motion provides an opportunity to distinguish between these strategies of 3D motion processing. Our theoretical results suggest that velocity constraints and disparity from feature tracking are needed to solve the inverse problem of 3D motion perception. It seems plausible that motion and disparity input is processed in parallel and integrated late in the visual processing hierarchy

Magnitude, precision, and realism of depth perception in stereoscopic vision

Our perception of depth is substantially enhanced by the fact that we have binocular vision. This provides us with more precise and accurate estimates of depth and an improved qualitative appreciation of the three-dimensional (3D) shapes and positions of objects. We assessed the link between these quantitative and qualitative aspects of 3D vision. Specifically, we wished to determine whether the realism of apparent depth from binocular cues is associated with the magnitude or precision of perceived depth and the degree of binocular fusion. We presented participants with stereograms containing randomly positioned circles and measured how the magnitude, realism, and precision of depth perception varied with the size of the disparities presented. We found that as the size of the disparity increased, the magnitude of perceived depth increased, while the precision with which observers could make depth discrimination judgments decreased. Beyond an initial increase, depth realism decreased with increasing disparity magnitude. This decrease occurred well below the disparity limit required to ensure comfortable viewing

Effect of Correlated tRNA Abundances on Translation Errors and Evolution of Codon Usage Bias

Despite the fact that tRNA abundances are thought to play a major role in determining translation error rates, their distribution across the genetic code and the resulting implications have received little attention. In general, studies of codon usage bias (CUB) assume that codons with higher tRNA abundance have lower missense error rates. Using a model of protein translation based on tRNA competition and intra-ribosomal kinetics, we show that this assumption can be violated when tRNA abundances are positively correlated across the genetic code. Examining the distribution of tRNA abundances across 73 bacterial genomes from 20 different genera, we find a consistent positive correlation between tRNA abundances across the genetic code. This work challenges one of the fundamental assumptions made in over 30 years of research on CUB that codons with higher tRNA abundances have lower missense error rates and that missense errors are the primary selective force responsible for CUB

The Spitzer Microlensing Program As A Probe For Globular Cluster Planets: Analysis Of Ogle-2015-BLG-0448

The microlensing event OGLE-2015-BLG-0448 was observed by Spitzer and lay within the tidal radius of the globular cluster NGC 6558. The event had moderate magnification and was intensively observed, hence it had the potential to probe the distribution of planets in globular clusters. We measure the proper motion of NGC 6558 (${{\boldsymbol{\mu }}}_{\mathrm{cl}}(N,E)=(+0.36\pm 0.10,+1.42\pm 0.10)\;{\rm{mas}}\;{{\rm{yr}}}^{-1}$) as well as the source and show that the lens is not a cluster member. Even though this particular event does not probe the distribution of planets in globular clusters, other potential cluster lens events can be verified using our methodology. Additionally, we find that microlens parallax measured using Optical Gravitational Lens Experiment (OGLE) photometry is consistent with the value found based on the light curve displacement between the Earth and Spitzer

THE VALUE OF DISTANCE: ART’S CULTURAL IDENTITY AMIDST TECHNOLOGY’S TRANSFORMATIONS OF SPACE

This study explores technology’s propensity to transform our comprehensions of space, considering the implications of this for our understandings of the work of art and the value that we ascribe to it. With our encounters increasingly a by-product of technological interface, the central question of this work is posed as follows: In what ways (and to what degree) may we regard the contemporary conditions facing the art object (and the values that these elicit) as a consequence of our prevailing technological landscape and its capacity to re-configure our conceptions of space and place? In confronting this, the study begins by surveying recent public justifications made for the arts and the criteria by which their value is ascertained. A trend is recognised, in the growing prevalence of instrumental qualifiers for art’s worth (its quantifiable impacts as a social utility) and a shift away from intrinsic measures. In response to this, I propose the concept of Accumulative Value, arguing that the totality of an art object’s intellectual considerations and explorations (over historical time) are an intrinsic attribute of the object itself and a qualifier of its objective worth. The notion of value itself (with its varying interpretations) is then explored, followed by a contemporary re-evaluation of Walter Benjamin’s concept of the aura, arguing that in our present circumstances this notion may be used in description of an object’s fixed spatial locality. The degree to which technologies of telepresence undermine such locality is then examined, noting trends in technological progression toward an abolition of distance, in both a spatial and temporal sense, that diminish our ability to recognise Accumulative Value. In consummation, it is proposed that technologies, as Competitive Cognitive Artefacts, may play a role in manifesting a situation in which the intrinsic measures of art’s worth are progressively disregarded, yet, that the auric artwork can come to fulfil a timely imperative, in reconnecting us to a somatic relationship with space and a linear understanding of time; such perceivable phenomena that are jeopardised by technological transformations