1,312 research outputs found
Dissociating the effect of disruptive colouration on localisation and identification of camouflaged targets
Disruptive camouflage features contrasting areas of pigmentation across the animals’ surface that form false edges which disguise the shape of the body and impede detection. In many taxa these false edges feature local contrast enhancement or edge enhancement, light areas have lighter edges and dark areas have darker edges. This additional quality is often overlooked in existing research. Here we ask whether disruptive camouflage can have benefits above and beyond concealing location. Using a novel paradigm, we dissociate the time courses of localisation and identification of a target in a single experiment. We measured the display times required for a stimulus to be located or identified (the critical duration). Targets featured either uniform, disruptive or edge enhanced disruptive colouration. Critical durations were longer for identifying targets with edge enhanced disruptive colouration camouflage even when presented against a contrasting background, such that all target types were located equally quickly. For the first time, we establish empirically that disruptive camouflage not only conceals location, but also disguises identity. This shows that this form of camouflage can be useful even when animals are not hidden. Our findings offer insights into how edge enhanced disruptive colouration undermines visual perception by disrupting object recognition
Vlada Traven, La datcha en Russie de 1917 à nos jours
This book presents a clear and well-informed account of dacha settlement around Moscow in the Soviet era. Vlada Traven contends that the history of suburban and exurban development offers a rewarding perspective on the Soviet experience. She starts with the striking idea that the “normal” process of suburbanization around Russia’s major cities was blocked by the Revolution. In the early twentieth century, dacha settlements were rapidly being converted into dwellings for year-round occupancy. ..
Estimating Lower Limb Kinematics using a Lie Group Constrained EKF and a Reduced Wearable IMU Count
This paper presents an algorithm that makes novel use of a Lie group
representation of position and orientation alongside a constrained extended
Kalman filter (CEKF) to accurately estimate pelvis, thigh, and shank kinematics
during walking using only three wearable inertial sensors. The algorithm
iterates through the prediction update (kinematic equation), measurement update
(pelvis height, zero velocity update, flat-floor assumption, and covariance
limiter), and constraint update (formulation of hinged knee joints and
ball-and-socket hip joints). The paper also describes a novel Lie group
formulation of the assumptions implemented in the said measurement and
constraint updates. Evaluation of the algorithm on nine healthy subjects who
walked freely within a m room shows that the knee and hip
joint angle root-mean-square errors (RMSEs) in the sagittal plane for free
walking were and , respectively, while
the correlation coefficients (CCs) were and ,
respectively. The evaluation demonstrates a promising application of Lie group
representation to inertial motion capture under reduced-sensor-count
configuration, improving the estimates (i.e., joint angle RMSEs and CCs) for
dynamic motion, and enabling better convergence for our non-linear
biomechanical constraints. To further improve performance, additional
information relating the pelvis and ankle kinematics is needed.Comment: 6 pages. arXiv admin note: text overlap with arXiv:1910.0091
Recalibrating the cosmic star formation history
The calibrations linking observed luminosities to the star formation rate
depend on the assumed stellar population synthesis model, initial mass
function, star formation and metal enrichment history, and whether reprocessing
by dust and gas is included. Consequently the shape and normalisation of the
inferred cosmic star formation history is sensitive to these assumptions. Using
v2.2.1 of the Binary Population and Spectral Synthesis (\bpass) model we
determine a new set of calibration coefficients for the ultraviolet,
thermal-infrared, and, hydrogen recombination lines. These ultraviolet and
thermal infrared coefficients are 0.15-0.2 dex higher than those widely
utilised in the literature while the H coefficient is dex
larger. These differences arise in part due to the inclusion binary evolution
pathways but predominantly reflect an extension in the IMF to 300
and a change in the choice of reference metallicity. We use these new
coefficients to recalibrate the cosmic star formation history, and find
improved agreement between the integrated cosmic star formation history and the
in-situ measured stellar mass density as a function of redshift. However, these
coefficients produce new tension between star formation rate densities inferred
from the ultraviolet and thermal-infrared and those from H.Comment: 7 pages, 8 figures, accepted for publication in MNRA
Depositional and diagenetic characteristics of a phylloid algal mound, upper Palo Pinto Formation, Conley field, Hardeman County, Texas
Due to the character of the original source materials and the nature of batch digitization, quality control issues may be present in this document. Please report any quality issues you encounter to [email protected], referencing the URI of the item.Includes bibliographical references.Not availabl
Nebular Line Emission During the Epoch of Reionization
Nebular emission lines associated with galactic HII regions carry information
about both physical properties of the ionised gas and the source of ionising
photons as well as providing the opportunity of measuring accurate redshifts
and thus distances once a cosmological model is assumed. While nebular line
emission has been extensively studied at lower redshift there are currently
only few constraints within the epoch of reionisation (EoR, ), chiefly due
to the lack of sensitive near-IR spectrographs. However, this will soon change
with the arrival of the Webb Telescope providing sensitive near-IR spectroscopy
covering the rest-frame UV and optical emission of galaxies in the EoR. In
anticipation of Webb we combine the large cosmological hydrodynamical
simulation Bluetides with photoionisation modelling to predict the nebular
emission line properties of galaxies at . We find good agreement
with the, albeit limited, existing direct and indirect observational
constraints on equivalent widths though poorer agreement with luminosity
function constraints.Comment: 17 pages, accepted to MNRAS, significant modification from v1.0 data
available at https://stephenmwilkins.github.io/BluetidesEmissionLines_Public
Protein Interactions from Complexes: A Structural Perspective
By combining crystallographic information with protein-interaction data obtained through traditional experimental means, this paper determines the most appropriate method for generating protein-interaction networks that incorporate data derived from protein complexes. We propose that a combined method should be considered; in which complexes composed of five chains or less are decomposed using the matrix model, whereas the spoke model is used to derive pairwise interactions for those with six chains or more. The results presented here should improve the accuracy and relevance of studies investigating the topology of protein-interaction networks
Soccer Player Characteristics in English Lower-League Development Programmes: The Relationships between Relative Age, Maturation, Anthropometry and Physical Fitness
The relative age effect (RAE) and its relationships with maturation, anthropometry, and physical performance characteristics were examined across a representative sample of English youth soccer development programmes. Birth dates of 1,212 players, chronologically age-grouped (i.e., U9's-U18's), representing 17 professional clubs (i.e., playing in Leagues 1 & 2) were obtained and categorised into relative age quartiles from the start of the selection year (Q1 = Sep-Nov; Q2 = Dec-Feb; Q3 = Mar-May; Q4 = Jun-Aug). Players were measured for somatic maturation and performed a battery of physical tests to determine aerobic fitness (Multi-Stage Fitness Test [MSFT]), Maximal Vertical Jump (MVJ), sprint (10 & 20m), and agility (T-Test) performance capabilities. Odds ratio's (OR) revealed Q1 players were 5.3 times (95% confidence intervals [CI]: 4.08-6.83) more likely to be selected than Q4's, with a particularly strong RAE bias observed in U9 (OR: 5.56) and U13-U16 squads (OR: 5.45-6.13). Multivariate statistical models identified few between quartile differences in anthropometric and fitness characteristics, and confirmed chronological age-group and estimated age at peak height velocity (APHV) as covariates. Assessment of practical significance using magnitude-based inferences demonstrated body size advantages in relatively older players (Q1 vs. Q4) that were very-likely small (Effect Size [ES]: 0.53-0.57), and likely to very-likely moderate (ES: 0.62-0.72) in U12 and U14 squads, respectively. Relatively older U12-U14 players also demonstrated small advantages in 10m (ES: 0.31-0.45) and 20m sprint performance (ES: 0.36-0.46). The data identify a strong RAE bias at the entry-point to English soccer developmental programmes. RAE was also stronger circa-PHV, and relatively older players demonstrated anaerobic performance advantages during the pubescent period. Talent selectors should consider motor function and maturation status assessments to avoid premature and unwarranted drop-out of soccer players within youth development programmes
Characterising and identifying galaxy protoclusters
We study the characteristics of galaxy protoclusters using the latest L-GALAXIES semi-analytic model. Searching for protoclusters on a scale of ∼10 cMpc gives an excellent compromise between the completeness and purity of their galaxy populations, leads to high distinction from the field in overdensity space, and allows accurate determination of the descendant cluster mass. This scale is valid over a range of redshifts and selection criteria. We present a procedure for estimating, given a measured galaxy overdensity, the protocluster probability and its descendant cluster mass for a range of modelling assumptions, particularly taking into account the shape of the measurement aperture. This procedure produces lower protocluster probabilities compared to previous estimates using fixed size apertures. The relationship between active galactic nucleus (AGN) and protoclusters is also investigated and shows significant evolution with redshift; at z ∼ 2, the fraction of protoclusters traced by AGN is high, but the fraction of all AGNs in protoclusters is low, whereas atz ≥ 5 the fraction of protoclusters containing AGN is low, but most AGNs are in protoclusters. We also find indirect evidence for the emergence of a passive sequence in protoclusters at z ∼ 2, and note that a significant fraction of all galaxies reside in protoclusters at z ≥ 2, particularly the most massive
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