A positional discriminability model of linearorder judgments

The process of judging the relative order of stimuli in a visual array was investigated in three experiments. In the basic paradigm, a linear array of six colored lines was presented briefly, and subjects decided which of two target lines was the leftmost or rightmost (Experiment 1). The target lines appeared in all possible combinations of serial positions and reaction time (RT) was measured. Distance and semantic congruity effects were obtained, as well as a bowed serial position function. The RT pattern resembled that observed in comparable studies with memorized linear orderings. The serial position function was flattened when the background lines were homogeneously dissimilar to the target lines (Experiment 2). Both a distance effect and bowed serial position functions were obtained when subjects judged which of two target lines was below a black bar cue (Experiment 3). The results favored an analog positional discriminability model over a serial ends-inward scanning model. The positional discriminability model was proposed as a "core model" for the processes involved in judging relative order or magnitude in the domains of memory and perception

Ecohydraulic modelling of anabranching rivers

In this paper we provide the first quantitative evidence of the spatial complexity of habitat diversity across the flow regime for locally anabranching channels, and their potential increased biodiversity value in comparison to managed single-thread rivers. Ecohydraulic modelling is used to provide evidence for the potential ecological value of anabranching channels. Hydraulic habitat (biotopes) of an anabranched reach of the River Wear at Wolsingham, UK is compared with an adjacent artificially straightened single-thread reach downstream. 2D hydraulic modelling was undertaken across the flow regime. Simulated depth and velocity data were used to calculate Froude number (Fr) index; known to be closely associated with biotope type, allowing biotope maps to be produced for each flow simulation using published Fr limits. The gross morphology of the anabranched reach appears to be controlling flow hydraulics, creating a complex and diverse biotope distribution at low and intermediate flows. This contrasts markedly with the near uniform biotope pattern modelled for the heavily modified single-thread reach. As discharge increases the pattern of biotopes altered to reflect a generally higher energy system, interestingly, however, a number of low energy biotopes were activated through the anabranched reach as new sub-channels became inundated and this process is creating valuable refugia for macroinvertebrates and fish, during times of flood. In contrast, these low energy areas were not seen in the straightened single thread reach. Model results suggest that anabranched channels have a vital role to play in regulating flood energy on river systems and in creating and maintaining hydraulic habitat diversity

Conservation status of a recently described endemic land snail, Candidula coudensis, from the Iberian Peninsula

Research ArticleWe assessed the distribution, population size and conservation status of Candidula coudensis, a recently described endemic land snail from Portugal. From March 2013 to April 2014, surveys were carried out in the region where the species was described. We found an extent of occurrence larger than originally described, but still quite small (13.5 km2). The species was found mainly in olive groves, although it occurred in a variety of other habitats with limestone soils, including grasslands, scrublands and stone walls. Minimum population estimate ranged from 110,000–311,000 individuals. The main identified potential threats to the species include wildfires, pesticides and quarrying. Following the application of IUCN criteria, we advise a conservation status of either “Least Concern” or “Near-threatened” under criterion D (restricted population)info:eu-repo/semantics/publishedVersio

Computational and Biological Analogies for Understanding Fine-Tuned Parameters in Physics

In this philosophical paper, we explore computational and biological analogies to address the fine-tuning problem in cosmology. We first clarify what it means for physical constants or initial conditions to be fine-tuned. We review important distinctions such as the dimensionless and dimensional physical constants, and the classification of constants proposed by Levy-Leblond. Then we explore how two great analogies, computational and biological, can give new insights into our problem. This paper includes a preliminary study to examine the two analogies. Importantly, analogies are both useful and fundamental cognitive tools, but can also be misused or misinterpreted. The idea that our universe might be modelled as a computational entity is analysed, and we discuss the distinction between physical laws and initial conditions using algorithmic information theory. Smolin introduced the theory of "Cosmological Natural Selection" with a biological analogy in mind. We examine an extension of this analogy involving intelligent life. We discuss if and how this extension could be legitimated. Keywords: origin of the universe, fine-tuning, physical constants, initial conditions, computational universe, biological universe, role of intelligent life, cosmological natural selection, cosmological artificial selection, artificial cosmogenesis.Comment: 25 pages, Foundations of Science, in pres

In vivo assessment of diet-induced rat hepatic steatosis development by percutaneous single-fiber spectroscopy detects scattering spectral changes due to fatty infiltration

This study explores percutaneous single-fiber spectroscopy (SfS) of rat livers undergoing fatty infiltration. Eight test rats were fed a methionine-choline-deficient (MCD) diet, and four control rats were fed a normal diet. Two test rats and one control rat were euthanized on days 12, 28, 49, and 77 following initiation of the diet, after percutaneous SfS of the liver under transabdominal ultrasound guidance. Histology of each set of the two euthanized test rats showed mild and mild hepatic lipid accumulations on day 12, moderate and severe on day 28, severe and mild on day 49, and moderate and mild on day 77. Livers with moderate or higher lipid accumulation generally presented higher spectral reflectance intensity when compared to lean livers. Livers of the eight test rats on day 12, two of which had mild lipid accumulation, revealed an average scattering power of 0.37±0.14 in comparison to 0.07±0.14 for the four control rats (p<0.01). When livers of the test rats with various levels of fatty infiltration were combined, the average scattering power was 0.36±0.15 in comparison to 0.14±0.24 of the control rats (0.05<p<0.1). Increasing lipid accumulation in concentration and size seemed to cause an increase of the scattering power prior to increasing total spectral reflectance.Electrical and Computer EngineeringVeterinary Clinical Science

Incorporating the geometry of dispersal and migration to understand spatial patterns of species distributions

Dispersal and migration can be important drivers of species distributions. Because the paths followed by individuals of many species are curvilinear, spatial statistical models based on rectilinear coordinates systems would fail to predict population connectivity or the ecological consequences of migration or species invasions. I propose that we view migration/dispersal as if organisms were moving along curvilinear geometrical objects called smooth manifolds. In that view, the curvilinear pathways become the ‘shortest realised paths’ arising from the necessity to minimise mortality risks and energy costs. One can then define curvilinear coordinate systems on such manifolds. I describe a procedure to incorporate manifolds and define appropriate coordinate systems, with focus on trajectories (1D manifolds), as parts of mechanistic ecological models. I show how a statistical method, known as ‘manifold learning’, enables one to define the manifold and the appropriate coordinate systems needed to calculate population connectivity or study the effects of migrations (e.g. in aquatic invertebrates, fish, insects and birds). This approach may help in the design of networks of protected areas, in studying the consequences of invasion, range expansions, or transfer of parasites/diseases. Overall, a geometrical view to animal movement gives a novel perspective to the understanding of the ecological role of dispersal and migration

Transrectal ultrasound-integrated spectral optical tomography of hypoxic progression of a regressing tumor in a canine prostate

The objective of this study was to evaluate if transrectal optical tomography implemented at three wavelength bands for spectral detection could monitor changes of the hemoglobin oxygen saturation (SₜO₂) in addition to those of the total hemoglobin concentration ([HbT]) in lesions of a canine prostate, including an induced tumor modeling canine prostate cancer. Near-infrared (NIR) optical tomography was integrated with ultrasound (US) for transrectal imaging. Multi-spectral detection at 705 nm, 785 nm and 808 nm rendered measurements of [HbT] and SₜO₂. Canine transmissible venereal tumor (TVT) cells were injected into the right lobe of a dog's prostate gland, which had a pre-existing cyst in the left lobe. Longitudinal assessments of the prostate were performed weekly over a 63-day duration by NIR imaging concurrent with grey-scale and Doppler US. Ultrasonography revealed a bi-lobular tumor-mass regressing from day-49 to day-63. At day-49 this tumor-mass developed a hypoxic core that became larger and more intense by day-56 and expanded further by day-63. The tumor-mass presented a strong hyper-[HbT] feature on day-56 that was inconsistent with US-visualized blood flow. Histology confirmed two necrotic TVT foci within this tumor-mass. The cyst appeared to have a large anoxic-like interior that was greater in size than its ultrasonographically delineated lesion, and a weak lesional elevation of [HbT]. On day-56, the cyst presented a strong hyper-[HbT] feature consistent with US-resolved blood flow. Histology revealed acute and chronic hemorrhage in the periphery of the cyst. The NIR imaging features of two other TVT nodules and a metastatic lymph node were evaluated retrospectively. Transrectal US-integrated spectral optical tomography seems to enable longitudinal monitoring of intra-lesional oxygenation dynamics in addition to the hemoglobin content of lesions in the canine prostate.Electrical & Computer EngineeringVeterinary Clinical Science

In vivo percutaneous reflectance spectroscopy of fatty liver development in rats suggests that the elevation of the scattering power is an early indicator of hepatic steatosis

This study assessed whether there was a scattering spectral marker quantifiable by reflectance measurements that could indicate early development of hepatic steatosis in rats for potential applications to pre-procurement organ evaluation. Sixteen rats were fed a methionine-choline-deficient (MCD) diet and eight rats were fed a normal diet. Direct assessment of the liver parenchyma of rats in vivo was performed by percutaneous reflectance spectroscopy using a single fiber probe at the beginning of diet-intake and arbitrary post-diet-intake times up to 11 weeks to render longitudinal comparison. Histological sampling of the liver over the duration of diet administration was performed on two MCD-diet treated rats and one control rat euthanized after reflectance spectroscopy measurement. The images of hematoxylin/eosin-stained liver specimens were analyzed morphometrically to evaluate the lipid size changes associated with the level of steatosis. The MCD-diet-treated group (n=16) had mild steatosis in seven rats, moderate in three rats, severe in six rats, and no other significant pathology. No control rats (n=8) developed hepatic steatosis. Among the parameters retrieved from per-SfS, only the scattering power (can be either positive or negative) appeared to be statistically different between MCD-treated and control livers. The scattering power for the 16 MCD-diet-treated livers at the time of euthanasia and presenting various levels of steatosis was 0.33±0.21, in comparison to 0.036±0.25 of the eight control livers (p=0.0189). When evaluated at days 12 and 13 combined, the scattering power of the 16 MCD-diet-treated livers was 0.32±0.17, in comparison to 0.10±0.11 of the eight control livers (p=0.0017). All of four MCD-treated livers harvested at days 12 and 13 presented mild steatosis with sub-micron size lipid droplets, even though none of the MCD-treated livers were sonographically remarkable for fatty changes. The elevation of the scattering power may be a valuable marker indicating early hepatic steatosis before the steatosis is sonographically detectable.Electrical and Computer EngineeringVeterinary Clinical Science

Online Continual Learning on Sequences

Online continual learning (OCL) refers to the ability of a system to learn over time from a continuous stream of data without having to revisit previously encountered training samples. Learning continually in a single data pass is crucial for agents and robots operating in changing environments and required to acquire, fine-tune, and transfer increasingly complex representations from non-i.i.d. input distributions. Machine learning models that address OCL must alleviate \textit{catastrophic forgetting} in which hidden representations are disrupted or completely overwritten when learning from streams of novel input. In this chapter, we summarize and discuss recent deep learning models that address OCL on sequential input through the use (and combination) of synaptic regularization, structural plasticity, and experience replay. Different implementations of replay have been proposed that alleviate catastrophic forgetting in connectionists architectures via the re-occurrence of (latent representations of) input sequences and that functionally resemble mechanisms of hippocampal replay in the mammalian brain. Empirical evidence shows that architectures endowed with experience replay typically outperform architectures without in (online) incremental learning tasks.Comment: L. Oneto et al. (eds.), Recent Trends in Learning From Data, Studies in Computational Intelligence 89