Role Of Density Research Articles

Factors influencing the extent of category spanning in new ventures: The role of density

The success of new ventures is largely determined by their strategic market positioning. Category research centers on this topic but has largely neglected the contextual conditions that influence t...

Functional renormalization for repulsive Bose-Bose mixtures at zero temperature

We study weakly-repulsive Bose-Bose mixtures in two and three dimensions at zero temperature using the functional renormalization group (FRG). We examine the RG flows and the role of density and spin fluctuations. We study the condition for phase separation and find that this occurs at the mean-field point within the range of parameters explored. Finally, we examine the energy per particle and condensation depletion. We obtain that our FRG calculations compare favorably with known results from perturbative approaches for macroscopic properties.

The roles of density and oxygen concentration on the structure of silica aerogel: Insight from an atomistic study

The structure of silica aerogels has strong dependence on the density ρ and oxygen concentration. In this study, molecular dynamic simulations are performed to study the roles of ρ and O/Si molar ratio (OSMR) on the structure of silica aerogels. The average pore size and porosity of silica aerogels increase with decreasing ρ. The OSMR influences the structure by changing the forming ability of tenuous ligaments in silica aerogels. The forming ability of tenuous ligaments decreases with decreasing OSMR from 2.0 to 1.9; then increases with further decreasing OSMR to 1.5. The increasing tenuous ligaments in silica aerogel leads to the dispersed ligaments and small average pore size. This study explains the correlation between the ρ, OSMR and the structure of silica aerogel, which can further guide to tune the structure of silica aerogels in experiments.

The density dilemma: there is always too much and too little of it

ABSTRACT The paper’s main concern are the intersections of the urban fabric and process with their political ecologies and political pathologies. Density is the substrate of core debates we are having in geography, urban studies and urban practice. These debates have oscillated between the states of hope and panic about the role of density in our urban futures and they have been sharpened by the 2020 COVID-19 pandemic. The paper argues for a contextual and relational notion of density and points to a core dilemma of the concept of density: there is always either too much or too little of it.

The size-weight illusion comes along with improved weight discrimination.

When people judge the weight of two objects of equal mass but different size, they perceive the smaller one as being heavier. Up to date, there is no consensus about the mechanisms which give rise to this size-weight illusion. We recently suggested a model that describes heaviness perception as a weighted average of two sensory heaviness estimates with correlated noise: one estimate derived from mass, the other one derived from density. The density estimate is first derived from mass and size, but at the final perceptual level, perceived heaviness is biased by an object’s density, not by its size. Here, we tested the models’ prediction that weight discrimination of equal-size objects is better in lifting conditions which are prone to the size-weight illusion as compared to conditions lacking (the essentially uninformative) size information. This is predicted because in these objects density covaries with mass, and according to the model density serves as an additional sensory cue. Participants performed a two-interval forced-choice weight discrimination task. We manipulated the quality of either haptic (Experiment 1) or visual (Experiment 2) size information and measured just-noticeable differences (JNDs). Both for the haptic and the visual illusion, JNDs were lower in lifting conditions in which size information was available. Thus, when heaviness perception can be influenced by an object’s density, it is more reliable. This discrimination benefit under conditions that provide the additional information that objects are of equal size is further support for the role of density and the integration of sensory estimates in the size-weight illusion.

Disentanglement of density and rotation dependences of the field penetration threshold on the J-TEXT tokamak

The field penetration threshold of magnetic perturbations has been observed to vary non-monotonically with an increase of density in ohmic plasmas on the J-TEXT tokamak. This observation appears contradicting the previous empirical density scaling law. Disentanglement of plasma density and rotation dependences of the field penetration threshold has been carried out. It shows that the field penetration threshold depends only weakly on the density but linearly on the plasma rotation. This result is not only important for the prediction of error field tolerance in fusion devices, but also opens a question on the role of density in the forced magnetic reconnection process in magnetized plasmas.

The density bias: Capuchin monkeys (Sapajus apella) prefer densely arranged items in a food-choice task.

In the current work, we investigated whether capuchin monkeys preferred densely distributed resources to sparsely distributed resources in a 2-choice discrimination task with edible rewards. Capuchin monkeys were biased to select a denser food set over the same number of food items in a sparsely arranged set. Furthermore, increased density of the larger food set facilitated discrimination performance in quantity comparisons with a true difference in set size. These results align with previous studies demonstrating a preference for densely distributed food sets in infants and callitrichid primates, as well as previous evidence of a density bias among several rhesus macaques and capuchin monkeys in a computerized relative quantity discrimination task. Thus, the density bias appears to emerge across multiple domains and presentation formats for some primate species. The role of density in perceived numerosity by capuchin monkeys and other species as it pertains to the foraging domain is discussed. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Higher Density Development for Lower Cost Housing? Understanding the Multifamily Housing Market and the Role of Density in Multifamily Home Prices

This study documents the development and the characteristics of multifamily homes in the Portland metropolitan area and evaluate the roles of density and density-related factors in determining multifamily home prices. The study finds that medium-density multifamily homes sell at lower prices than other housing types in dollar per unit and dollar per square foot. The cost-saving effect of higher density development is weak or even negative, and dwelling size is the primary determinant of multifamily home prices. The effects of neighborhood density on home prices depend on housing types. Investors own almost a half of nonapartment multifamily homes and buy homes at lower prices.

Impact of Population Density on PM2.5 Concentrations: A Case Study in Shanghai, China

We examine the effects of the urban built environment on PM2.5 (fine particulate matter with diameters equal or smaller than 2.5 μm) concentrations by using an improved region-wide database, a spatial econometric model, and five built environment attributes: Density, design, diversity, distance to transit, and destination accessibility (the 5Ds). Our study uses Shanghai as a relevant case study and focuses on the role of density at the jiedao scale, the smallest administrative unit in China. The results suggest that population density is positively associated with PM2.5 concentrations, pointing to pollution centralization and congestion effects dominating the mitigating effects of mode-shifting associated with density. Other built environment variables, such as the proportion of road intersections, degree of mixed land use, and density of bus stops, are all positively associated with PM2.5 concentrations while distance to nearest primary or sub-center is negatively associated. Regional heterogeneity shows that suburban jiedao have lower PM2.5 concentrations when a subway station is present.

Cannibalism in temporary waters: Simulations and laboratory experiments revealed the role of spatial shape in the mosquito Aedes albopictus.

Cannibalism is a commonly observed phenomenon in arthropod species having relevant consequences for population dynamics and individual fitness. It is a context-dependent behaviour and an understanding of the factors affecting cannibalism rate is crucial to highlight its ecological relevance. In mosquitoes, cannibalism between larval stages has been widely documented, and the role of density, food availability and length of contact between individuals also ascertained. However, although mosquitoes can develop in temporary water habitats with very heterogeneous topologies, the role of the site shape where cannibals and victims co-occur has been instead overlooked. In this paper, we investigated this issue by using a simulation approach and laboratory cannibalism experiments between old (third- and fourth-instars) and young (first-instar) larvae of the tiger mosquito Aedes albopictus. Three virtual spaces with different shapes were simulated and the number of larval encounters was estimated in each one to assess whether the spatial shape affected the number of encounters between cannibal and victims. Then, experimental trials in containers with similar shapes to those used in the simulations were performed, and the cannibalism rate was estimated at 24 and 48h. Our results showed that the spatial shape plays a role on cannibalism interactions, affecting the number of encounters between individuals. Indeed, in the experimental trials performed, we observed the highest cannibalism rate in the container with the highest number of encounters predicted by the simulations. Interestingly, we found also that spatial shape can affect cannibalism not only by affecting the number of encounters, but also the number of encounters “favorable” for cannibalistic events. Temporary waters are inhabited by several species other than mosquitoes. Our results, showing an influence of the spatial shape on cannibalism in Ae. albopictus larvae, add a new critical factor to those affecting ecological interactions in these habitats.

On the role of density and attenuation in three-dimensional multiparameter viscoacoustic VTI frequency-domain FWI: an OBC case study from the North Sea

3-D frequency-domain full waveform inversion (FWI) is applied on North Sea wide-azimuth ocean-bottom cable data at low frequencies (≤10 Hz) to jointly update vertical wave speed, density and quality factor Q in the viscoacoustic VTI approximation. We assess whether density and Q should be viewed as proxy to absorb artefacts resulting from approximate wave physics or are valuable for interpretation in the presence of soft sediments and gas cloud. FWI is performed in the frequency domain to account for attenuation easily. Multiparameter frequency-domain FWI is efficiently performed with a few discrete frequencies following a multiscale frequency continuation. However, grouping a few frequencies during each multiscale step is necessary to mitigate acquisition footprint and match dispersive shallow guided waves. Q and density absorb a significant part of the acquisition footprint hence cleaning the velocity model from this pollution. Low Q perturbations correlate with low-velocity zones associated with soft sediments and gas cloud. However, the amplitudes of the Q perturbations show significant variations when the inversion tuning is modified. This dispersion in the Q reconstructions is however not passed on the velocity parameter suggesting that cross-talks between first-order kinematic and second-order dynamic parameters are limited. The density model shows a good match with a well log at shallow depths. Moreover, the impedance built a posteriori from the FWI velocity and density models shows a well-focused image with however local differences with the velocity model near the sea bed where density might have absorbed elastic effects. The FWI models are finally assessed against time-domain synthetic seismogram modelling performed with the same frequency-domain modelling engine used for FWI.

Thiolated gold nanoparticle solvation in near-critical fluids: The role of density, temperature, and topology.

We employ molecular dynamics simulations to study the structure and solvation thermodynamics of thiolated gold nanoparticles of size 1.2 and 1.6 nm with ligand of chain length 8-16 carbons in ethane and propane over a wide range of densities close to the critical isotherm. The Helmholtz free energy is estimated by explicitly calculating the change in entropy and internal energy of solvation, and the effect of density and temperature on fluctuation-driven inherent anisotropy in the ligand corona is characterized. Since the topological variation further accentuates this instantaneous asymmetry in the ligand cloud, the anisotropy with varying surface coverage and chain length is also studied including the solvent contributions to the entropic and energetic metrics. Our results are consistent with the experiment, suggesting a route of obtaining structural insights into solvation thermodynamics that could be useful for understanding the stability of nanoparticle dispersions.

Effects of stocking density on the individual growth and differentiation of the oriental river prawn Macrobrachium nipponense (de Haan, 1849) (Caridea: Palaemonidae)

We evaluated the effect of stocking density on the concentrations of oxy-hemocyanin and lactate in hemolymph, the antioxidant ability of the hepatopancreas, and the biochemical composition in large and small individuals of the prawn Macrobrachium nipponense (de Haan, 1849) cultured in a cage system. Juveniles (0.24 g initial weight) were stocked in 15 cages with stocking densities of 40, 80, 120, 160, and 200 individuals/m2 for 8 weeks. The results demonstrated that final mean weight, weight gain, gross feed conversion ratio, and survival rate were significantly lower in stocking densities of 160 and 200 individuals/m2 (P<0.05) than in other treatment groups, not through water quality deterioration or food competition, but through the role of density as an environmental stress factor. The coefficient of variation (CV) of body weight increased as the stocking density increased, and the CV in the 160 and 200 individuals/m2 groups were over 70%. The values of hemolymph oxy-hemocyanin and lactate concentration, superoxide dismutase (SOD), catalase (CAT) activities, malondialdehyde (MDA) content, and heat-shock protein 70 (HSP70) mRNA expressions of hepatopancreas in small individuals were significantly higher than those of the large ones in high stocking densities of 160 and 200 individuals/m2. This study provides evidence that crowding stress can stimulate the physiological response of the small individuals raising their oxy-hemocyanin and lactate level in the hemolymph and decreasing antioxidant ability on hepatopancreas, which ultimately lead to suppress growth performance of the small individuals.

Unpacking ‘the City’: An experience-based approach to the role of urban living in psychosis

Primarily on the basis of epidemiological studies, recent research in psychiatry has established a robust link between urban living and psychosis. This paper argues first, that an experienced-based approach, moving beyond epidemiology, is needed in order to enable more fine-grained understandings of the city/psychosis nexus. The second part of the paper presents preliminary fieldwork results based on video-elicitation sessions with first-episode patients with psychotic disorders. These results lead to the generation of a series of hypotheses for further research on the role of density, sensory overload and social interaction as factors in the onset of non-affective psychoses. The conclusion discusses the insights gained from viewing the city as an experiential milieu rather than as a set of substances. We argue that such insights enable, on the one hand, observation of the role of specific places and situations - and thus to unpack ‘the city’; and, on the other, to envisage the urban milieu as a nexus of possible sites of recovery.

Size effects and the role of density on the viscosity of water confined in carbon nanotubes

Equilibrium molecular dynamics simulations were carried out in order to determine the viscosity of water confined into carbon nanotubes. We have found that the viscosity of confined water is about an order of magnitude lower than bulk and increase non-linearly with nanotube diameter. We quantify the influence of density of water upon its viscosity, and observed a strong dependence between both quantities. After analysis of density profiles and diffusion coefficients we conclude that water at high density regime experiences a structural transition resulting in a large increment in viscosity.

Impact Strength of Laminated Floor Panel from Kenaf&lt;i&gt; (Hibiscus cannabinus)&lt;/i&gt; High Density Fibreboard

This study provides a better understanding of the effect of density and thickness on impact strength of laminated floor panel from Kenaf high density fibreboard (KHDF). The objective of this study was therefore to determine the role of density and thickness on the impact strength of laminated floor panel. Laminated floor panels consisted of high density fibreboard (HDF) as core and decorative paper as surface layer and backing. Kenaf bast fibres were used for HDF with three different densities (850, 960 and 1000 kg/m3) with thickness of 8mm and 12mm for each panel. Energy (J) value was evaluated to determine the impact strength of all various floor panels. It was found that thickness has affected statistically on impact strength while there was no significantly difference existed on density of laminated floor panel on impact strength.

서비스케이프, 이용밀도 및 방문객 만족간의 관계분석

This study is to analyze the effect of servicescape on the satisfaction of visitors to water park and role of the density as a moderating variable. The hypotheses were formulated for the study and the in-depth empirical analysis was made on the Wongjin Playdoci Water Park. The analysis results showed that the Water Park's servicescape is composed of four factors such as 'attractiveness', 'comfort', 'convenience and safety‘ and ’facility's diversity‘. It looks like that the elements of 'attractiveness', 'comfort', 'safety' and 'facility's diversity’ reflect the physical environment of the water park. On the other hand, the verification of the hypotheses showed the followings. The hypothesis 1 stating that the components of the service scape affects the satisfaction of visitors was supported and it was found that the factors are affecting the satisfaction of visitors in the order of 'attractiveness', 'facility's diversity', 'convenience and safety' and 'comfort'. In addition, the hypothesis 2 stating that the effect of factors of the servicescape on the satisfaction of visitor depends on the use density was also supported. The study results have the implications that in case of water park, the attractiveness shall be put priority for the enhanced satisfaction of visitors in the same as the general theme parks and that the detailed consideration shall be given to the 'comfort' and 'convenience and safety' as they show the big difference in the satisfaction depending on the use density, which is the moderating variable. This study has meaning that it has derived the factors of servicescape in the water park and that the role of use density has been verified in the relation between servicescape and the satisfaction.

The influence of inflammation on mammographic breast density in women at increased risk of breast cancer.

1566 Background: Mammographic density is an important risk factor for breast cancer but the etiology of density is not well understood. Studies suggest that inflammation may play a role in density....

The role of density and relatedness in wild juvenile A tlantic salmon growth

Growth is a key life-history trait in fish that is influenced by both abiotic (such as temperature and water chemistry) and biotic factors (such as density and food availability). Investigating how growth performance is influenced by such factors in the wild is important for understanding how population processes influence animals in natural environments and for predicting the response to conservation and management strategies that manipulate these conditions. The theory of kin selection predicts that significant growth and survival benefits are conferred upon animals associating with close relatives. However, resource competition may be more intense among close relatives, and little is known about the trade-off between these two processes under different ecological conditions. Here, we examine the correlation between naturally occurring densities and kin-biased growth rate using a species where kin recognition has a strong impact on behaviour in laboratory studies, but where, paradoxically, field investigations have failed to document predicted kin-biased growth or survival. Intra- and inter-family differences in growth rate of juvenile Atlantic salmon Salmo salar were studied to examine how relatedness (groups of full-sibling fish and groups of mixed-sibling fish) and sibling group (family/genotype) affect salmon parr growth, and the correlation of growth rate under a range of naturally occurring densities. Parentage and relatedness of neighbouring fish were assigned using microsatellite and passive integrated transponder tags, which allowed the growth estimation of individual fish. The results show that growth rate was significantly influenced by both sibling group (family of origin) and also by an interaction between relatedness and density. The latter finding indicates that at higher densities, full-sibling groups achieved higher growth rates in comparison to mixed-sibling groups. Thus, the growth benefits of associating with relatives are not conferred under all ecological conditions, but it becomes most apparent at high density when resource competition is greatest.

Role of density in aggregation patterns and synchronization of spawning in the hermaphroditic scallop Pecten fumatus

In broadcast spawners, low densities and poor spawning synchronization can reduce fertilization success. In wild populations, individuals in close proximity tend to spawn more synchronously than those further apart, sug- gesting that low spawner densities may reduce gamete pro- duction by lessening the efficacy of pheromone signalling. This study assessed the role of adult density in aggregation patterns and spawning synchronization in a semi-sessile, hermaphroditic scallop, Pecten fumatus. The study was carried out in Great Bay, Tasmania, Australia (147.335 W, 43.220 S) in 2010-2012 by assessing (1) the relationship between density, small-scale aggregation patterns and near- est neighbour distance (NND), (2) the temporal pattern of spawning synchronization, and (3) the effect of site density and conspecific proximity on the probability of spawn- ing. Densities observed in the field ranged from 1.455 to 0.021 ind m −2 . Sites with lower densities had less small- scale aggregation and greater NNDs. Patterns of small- scale aggregation and NNDs in P. fumatus were compara- ble to those observed in a gonochoristic species. Spawning synchronization was highly variable, ranging between 3.5