Evidence for Gravity as a Cue for Absolute Size and Distance

1994 ◽  
Author(s):  
Heiko Hecht ◽  
Mary K. Kaiser ◽  
Martin S. Banks
Keyword(s):  
Absolute Size

Distance to SN 1987A and the LMC

1999 ◽  
Vol 190 ◽  
pp. 549-554
Author(s):  
Nino Panagia
Keyword(s):  
Angular Size ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Light Curves ◽  
Distance Modulus ◽  
Absolute Size ◽  
Sn 1987A

Using the new reductions of the IUE light curves by Sonneborn et al. (1997) and an extensive set of HST images of SN 1987A we have repeated and improved Panagia et al. (1991) analysis to obtain a better determination of the distance to the supernova. In this way we have derived an absolute size of the ringRabs= (6.23 ± 0.08) x 1017cm and an angular sizeR″ = 808 ± 17 mas, which give a distance to the supernovad(SN1987A) = 51.4 ± 1.2 kpc and a distance modulusm–M(SN1987A) = 18.55 ± 0.05. Allowing for a displacement of SN 1987A position relative to the LMC center, the distance to the barycenter of the Large Magellanic Cloud is also estimated to bed(LMC) = 52.0±1.3 kpc, which corresponds to a distance modulus ofm–M(LMC) = 18.58±0.05.

Cosserat Modeling of Size Effects in Crystalline Solids

2000 ◽  
Vol 653 ◽  
Author(s):  
Samuel Forest
Keyword(s):  
Stress State ◽  
Size Effects ◽  
Elastic Inclusion ◽  
Characteristic Size ◽  
Infinite Matrix ◽  
Crystalline Solids ◽  
Generalized Continua ◽  
Absolute Size ◽  
Kink Bands ◽  
The Matrix

AbstractThe mechanics of generalized continua provides an efficient way of introducing intrinsic length scales into continuum models of materials. A Cosserat framework is presented here to descrine the mechanical behavior of crystalline solids. The first application deals with the problem of the stress field at a crak tip in Cosserat single crystals. It is shown that the strain localization patterns developping at the crack tip differ from the classical picture : the Cosserat continuum acts as a bifurcation mode selector, whereby kink bands arising in the classical framework disappear in generalized single crystal plasticity. The problem of a Cosserat elastic inclusion embedded in an infinite matrix is then considered to show that the stress state inside the inclusion depends on its absolute size lc. Two saturation regimes are observed : when the size R of the inclusion is much larger than a characteristic size of the medium, the classical Eshelby solution is recovered. When R is much small than the inclusion, a much higher stress is reached (for an inclusion stiffer than the matrix) that does not depend on the size any more. There is a transition regime for which the stress state is not homogeneous inside the inclusion. Similar regimes are obtained in the study of grain size effects in polycrystalline aggregates of Cosserat grains.

EXPRESS: How the size of exogenous attentional cues alters visual performance: from response gain to contrast gain

2021 ◽  
pp. 174702182110248
Author(s):  
Xiaogang Wu ◽  
Aijun Wang ◽  
Ming Zhang
Keyword(s):  
Visual Selective Attention ◽  
Visual Performance ◽  
Target Size ◽  
Field Size ◽  
Gain Modulation ◽  
Absolute Size ◽  
Contrast Gain ◽  
Exogenous Cues ◽  
Exogenous Cue ◽  
Attentional Cues

The normalization model of attention (NMoA) predicts that the attention gain pattern is mediated by changes in the size of the attentional field and stimuli. However, existing studies have not measured gain patterns when the relative sizes of stimuli are changed. To investigate the NMoA, the present study manipulated the attentional field size, namely, the exogenous cue size. Moreover, we assessed whether the relative rather than the absolute size of the attentional field matters, either by holding the target size constant and changing the cue size (experiments 1-3) or by holding the cue size constant and changing the target size (experiment 4), in a spatial cueing paradigm of psychophysical procedures. The results show that the gain modulations changed from response gain to contrast gain when the precue size changed from small to large relative to the target size (experiments 1-3). Moreover, when the target size was once again made larger than the precue size, there was still a change in response gain (experiment 4). These results suggest that the size of exogenous cues plays an important role in adjusting the attentional field and that relative changes rather than absolute changes to exogenous cue size determine gain modulation. These results are consistent with the prediction of the NMoA and provide novel insights into gain modulations of visual selective attention.

The Physical Anthropologist as Craniofacial Biologist

2002 ◽  
Vol 24 (1) ◽  
pp. 32-34
Author(s):  
Edward Harris
Keyword(s):  
Fourth Dimension ◽  
Spatial Relationships ◽  
Progressive Change ◽  
Absolute Size ◽  
Good Ability ◽  
Physical Anthropologist ◽  
Different Tissues

Growth—the progressive change in size and complexity of a person as he moves toward maturity—is often viewed as anatomy's "fourth dimension." It is the "dimension" that provides change: change in size, in proportionality, in morphology, in spatial relationships of structures, in complexity, as well as profound changes in the child's psychological and behavioral framework. As we all appreciate, an adult is not just a very large infant; instead, different tissues and structures have their own agespecific patterns of growth, which accounts for our pretty good ability to determine someone's age simply from their proportions (as in a photograph) without regard to their absolute size.

Failure Mechanisms of Particulate Two-Phase Composites

1998 ◽  
Vol 529 ◽  
Author(s):  
T. Antretter ◽  
E D. Fischer
Keyword(s):  
Residual Stresses ◽  
Crack Growth ◽  
Opening Angle ◽  
Geometrical Parameters ◽  
Two Phase ◽  
Absolute Size ◽  
The Matrix ◽  
Unit Cells ◽  
Angle Criterion ◽  
Probability Of Fracture

AbstractIn many composites consisting of hard and brittle inclusions embedded in a ductile matrix failure can be attributed to particle cleavage followed by ductile crack growth in the matrix. Both mechanisms are significantly sensitive towards the presence of residual stresses.On the one hand particle failure depends on the stress distribution inside the inclusion, which, in turn, is a function of various geometrical parameters such as the aspect ratio and the position relative to adjacent particles as well as the external load. On the other hand it has been observed that the absolute size of each particle plays a role as well and will, therefore, be taken into account in this work by means of the Weibull theory. Unit cells containing a number of quasi-randomly oriented elliptical inclusions serve as the basis for the finite element calculations. The numerical results are then correlated to the geometrical parameters defining the inclusions. The probability of fracture has been evaluated for a large number of inclusions and plotted versus the particle size. The parameters of the fitting curves to the resulting data points depend on the choice of the Weibull parameters.A crack tip opening angle criterion (CTOA) is used to describe crack growth in the matrix emanating from a broken particle. It turns out that the crack resistance of the matrix largely depends on the distance from an adjacent particle. Residual stresses due to quenching of the material tend to reduce the risk of particle cleavage but promote crack propagation in the matrix.

Gravity as a Monocular Cue for Perception of Absolute Distance and/or Absolute Size

Perception ◽  
1992 ◽  
Vol 21 (1) ◽  
pp. 69-76 ◽  
Author(s):  
John S Watson ◽  
Martin S Banks ◽  
Claes von Hofsten ◽  
Constance S Royden
Keyword(s):  
Wave Motion ◽  
Moving Objects ◽  
Formal Analysis ◽  
Free Fall ◽  
Absolute Distance ◽  
Absolute Size ◽  
The Absolute ◽  
Pendulum Wave

When the motion of an object is influenced by gravity (eg free fall, pendulum, wave motion), that influence may provide a cue to computing the absolute distance and/or size of the object. Formal analysis supports the claim that the distance and size of moving objects are generally computable with reference to the gravitational component of motion. Informal evidence from judgments of realism in films is consistent with this gravity-cue hypothesis.

scholarly journals Fertility and its relation to social conditions A study of the vital statistics of London in 1930–1932

1937 ◽  
Vol 37 (1) ◽  
pp. 108-123 ◽  
Author(s):  
K. Mitra
Keyword(s):  
Birth Rate ◽  
Western Europe ◽  
Vital Statistics ◽  
Considerable Extent ◽  
The Other ◽  
Rapid Decline ◽  
Relative Importance ◽  
Absolute Size ◽  
The Military

The rapid decline of the birth-rate in nearly all countries of western Europe has naturally attracted much attention. Some have studied the probable effects upon the absolute size and the age constitution of the population, and the consequence entailed upon the military and economic strength of a nation. Others have drawn attention to resulting change's in the relative importance of diseases of young, adult and old ages. Changes in mere numbers depend wholly, and the other changes to a considerable extent, upon quantitative factors; they must occur even if the quality of those born differs in no way from that of those produced when fertility was at a higher level. But, if the quality of births changes with their quantity, then the consequences of decrease of numbers may be better or worse than mere numerical changes would involve.

scholarly journals Serological level of transforming growth factor-β as a predictive biomarker of aortic enlargement in patients with Marfan syndrome

2017 ◽  
Vol 8 (1) ◽  
pp. 61-66
Author(s):  
Andrey S Rudoy ◽  
Alexey M Uryvaev
Keyword(s):  
Risk Factors ◽  
Growth Factor ◽  
Marfan Syndrome ◽  
Aortic Root ◽  
Transforming Growth Factor ◽  
Aortic Rupture ◽  
Imaging Techniques ◽  
Elevated Serum ◽  
Transforming Growth Factor Β ◽  
Absolute Size

Marfan syndrome - an inherited, autosomal dominant disease with an expected rate of 3-5/10 000 or fraction of 20-25% of new mutations, accompanied by violation of the connective tissue that occurs as a result of gene mutations FBN1, coding for the synthesis of fibrillin-1, performing the most important role in the modulation physiological bioavailability TGF-β (transforming growth factor-β). Prediction of aortic rupture is based on the identification of risk factors: family history, the absolute size of the aortic root, the rate of expansion of the aorta, which are based on the results of the history and techniques of imaging ultrasound, CT, MRI. At the same time there is a chance of developing aortic rupture under normal aortic root size and the absence of any risk factors, as well as after the prophylactic prosthetic aortic root. This makes it necessary to search for alternative prognostic markers, threatening bundle and rupture of the aorta. Article verified the predictive role of TGF-β as a serological biomarker for assessing the extension of the aortic root in patients with Marfan syndrome (n = 23, F : M / 7 : 16; 33 ± 9.3 years). The article describes the patterns between TGF-β and the size and the reconstruction of the aneurysm of the thoracic aorta. It was found that elevated levels of serum TGF-β1 (49.1 ng/ml Vs 29.15 ng/ml in the control, p < 0.05) in patients with MS diagnosed with an extension of the aortic root (Z > 1.96) can serve as a serological marker to poor prognosis, accompanied by an increase in the size of the aortic root. In patients with normal-sized aorta, and after aortic reconstruction serum TGFβ1 not elevated. Serum TGFβ may be a promising target for therapeutic, diagnostic and prognostic tactics which are not based on imaging techniques.

scholarly journals Relative skull size as one of the factors limiting skull shape variation in passerines

2021 ◽  
Author(s):  
Oksana Shatkovska ◽  
Maria Ghazali
Keyword(s):  
Body Mass ◽  
Shape Variation ◽  
Absolute Size ◽  
Terrestrial Locomotion ◽  
Skull Shape ◽  
Skull Size ◽  
Dietary Preferences ◽  
Wide Range ◽  
Body Sizes ◽  
Biomechanical Constraints

Despite a considerable interest of researchers to the issue of variation in skull shapes of birds and factors influencing it, some drivers associated with the design features of an entire bird body, which are important for both successful terrestrial locomotion and flight, are overlooked. One of such factors, in our opinion, is relative skull size (skull length in relation to body mass), which can affect the position of the body's center of gravity. We tested effects of relative skull size, allometry (i.e. absolute skull size), and diet on variation in skull shape. The study was conducted on 50 songbird species with a wide range of body mass (8.3g to 570g) and dietary preferences (granivores, insectivores/granivores, insectivores, omnivores). Skull shape was analyzed using 2D geometric morphometrics. We revealed that similar patterns of skull shape occur among passerines with different body sizes and diets. The relative skull size predicted skull shape to a similar extent and with a similar pattern as the absolute size. In our opinion, the effect of the relative skull size on skull shape variation is likely due to biomechanical constraints related to flight.

scholarly journals Estimation of the parameters of fish stock dynamics from catch-at-age data and indices of abundance: can natural and fishing mortality be separated?

2007 ◽  
Vol 64 (8) ◽  
pp. 1130-1142 ◽  
Author(s):  
Sondre Aanes ◽  
Steinar Engen ◽  
Bernt-Erik Sæther ◽  
Ronny Aanes
Keyword(s):  
Gadus Morhua ◽  
State Space Model ◽  
Population Projections ◽  
Quality Data ◽  
Fish Stock ◽  
Natural Mortality ◽  
Fishing Mortality ◽  
Absolute Size ◽  
Data Set ◽  
Long Time

Models for fluctuations in size of fish stocks must include parameters that describe expected dynamics, as well as stochastic influences. In addition, reliable population projections also require assessments about the uncertainties in estimates of vital parameters. Here we develop an age-structured model of population dynamics based on catch-at-age data and indices of abundance in which the natural and fishing mortality are separated in a Bayesian state–space model. Markov chain Monte Carlo methods are used to fit the model to the data. The model is fitted to a data set of 19 years for Northeast Arctic cod (Gadus morhua). By simulations of the fitted model we show that the model captures the dynamical pattern of natural mortality adequately, whereas the absolute size of natural mortality is difficult to estimate. Access to long time series of high-quality data are necessary for obtaining precise estimates of all the parameters in the model, but some parameters cannot be estimated without including some prior information. Nevertheless, our model demonstrates that temporal variability in natural mortality strongly affects perceived variability in stock sizes. Thus, using estimation procedures that neglect temporal fluctuations in natural mortality may therefore give biased estimates of fluctuations in fish stock sizes.

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