Towards a universal description of cohesive-particle flows
NASA Astrophysics Data System (ADS)
Lamarche, Casey; Liu, Peiyuan; Kellogg, Kevin; Lattanzi, Aaron; Hrenya, Christine
2017-11-01
A universal framework for describing cohesive granular flows seems unattainable based on prior works, making a fundamental continuum theory to predict such flows appear unachievable. For the first time, universal behavior of cohesive-grain flows is demonstrated by linking the macroscopic (many-grain) behavior to grain-grain interactions via two dimensionless groups: a generalized Bond number BoG - ratio of maximum cohesive force to the force driving flow - and a new Agglomerate number Ag - ratio of critical cohesive energy to the granular energy. Cohesive-grain flow is investigated in several systems, and universal behavior is determined via collapse of a cohesion-dependent output variable from each system with the appropriate dimensionless group. Universal behavior is observed using BoG for dense (enduring-contact-dominated) flows and Ag for dilute (collision-dominated) flows, as BoG accounts for the cohesive contact force and Ag for increased collisional dissipation due to cohesion. Hence, a new physical picture is presented, namely, BoG dominates in dense flows, where force chains drive momentum transfer, and Ag dominates in dilute systems, where the dissipative collisions dominate momentum transfer. Apparent discrepancies with past treatments are resolved. Dow Corning Corporation.
Dorsett, Dale
2006-01-01
The sister chromatid cohesion apparatus mediates physical pairing of duplicated chromosomes. This pairing is essential for appropriate distribution of chromosomes into the daughter cells upon cell division. Recent evidence shows that the cohesion apparatus, which is a significant structural component of chromosomes during interphase, also affects gene expression and development. The Cornelia de Lange (CdLS) and Roberts/SC phocomelia (RBS/SC) genetic syndromes in humans are caused by mutations affecting components of the cohesion apparatus. Studies in Drosophila suggest that effects on gene expression are most likely responsible for developmental alterations in CdLS. Effects on chromatid cohesion are apparent in RBS/SC syndrome, but data from yeast and Drosophila point to the likelihood that changes in expression of genes located in heterochromatin could contribute to the developmental deficits. PMID:16819604
Social cohesion, cultural identity, and drug use in Mexican rural communities.
Wagner, Fernando; Diaz, David B; López, Aida L; Collado, Ma Elena; Aldaz, Evelyn
2002-01-01
The objective of this study was to explore drug use in Mexican rural communities and its relationship to social cohesion, cultural identity, migration, and transculturation. Community models typification was used, considering cohesion as the central point of analysis. The research was conducted during 15-day periods in each of nine communities during 1991. Both documentary and ethnographic techniques were used to gather information. Results indicated that rural communities where there was little or no drug use among its members show more social cohesion, cultural identity, and community links consolidation, and more capacity for integrating change. This pattern is most apparent among young community members who have had more contact with the outer world (drug trafficking, North American culture, and Mexican urban culture).
Cohesion as a Command Emphasis Item
2010-03-01
of the notion of cohesion— social cohesion . Social cohesion is the affective bonding between members; or to expound further, the interpersonal...team to achieve that goal. 3 Members with high task cohesion do not necessarily share high social cohesion . The reason this distinction is...important is due to the fact that when thinking in terms of cohesion, most leaders think of it in terms of social cohesion . Unfortunately, studies of the
Morphine reduces social cohesion in rats.
Panksepp, J; Najam, N; Soares, F
1979-08-01
The effect of low (1 mg/kg) doses of morphine on maintenance of physical proximity were evaluated in paired rats observed in a 4 square foot test arena. Morphine reliably reduced proximity maintenance time, and this was apparently not due to sedation, since the effect was unmodified by doses of amphetamine which substantially increased motor activity. The effects of naloxone were inconsistent on this measure of social motivation. In general, the results are consistent with the theoretical proposition that a brain neurochemical change which might lead to social attraction is the activation of endogenous opioid systems. When opiate activity is exogenously sustained, animals exhibit a subnormal tendency to be gregarious.
The socio-matrix reloaded: from hierarchy to dominance profile in wild lemurs.
Norscia, Ivan; Palagi, Elisabetta
2015-01-01
Dominance hierarchy influences the life quality of social animals, and its definition should in principle be based on the outcome of agonistic interactions. However, defining and comparing the dominance profile of social groups is difficult due to the different dominance measures used and because no one measure explains it all. We applied different analytical methods to winner-loser sociomatrices to determine the dominance profile of five groups of wild lemurs (species: Lemur catta, Propithecus verreauxi, and Eulemur rufus x collaris) from the Berenty forest (Madagascar). They are an excellent study model because they share the same habitat and an apparently similar dominance profile: linear hierarchy and female dominance. Data were collected over more than 1200 h of observation. Our approach included four steps: (1) by applying the binary dyadic dominance relationship method (I&SI) on either aggressions or supplant sociomatrices we verified whether hierarchy was aggression or submission based; (2) by calculating normalized David's scores and measuring steepness from aggression sociomatrices we evaluated whether hierarchy was shallow or steep; (3) by comparing the ranking orders obtained with methods 1 and 2 we assessed whether hierarchy was consistent or not; and (4) by assessing triangle transitivity and comparing it with the linearity index and the level of group cohesion we determined if hierarchy was more or less cohesive. Our results show that L. catta groups have got a steep, consistent, highly transitive and cohesive hierarchy. P. verreauxi groups are characterized by a moderately steep and consistent hierarchy, with variable levels of triangle transitivity and cohesion. E. rufus x collaris group possesses a shallow and inconsistent hierarchy, with lower (but not lowest) levels of transitivity and cohesion. A multiple analytical approach on winner-loser sociomatrices other than leading to an in-depth description of the dominance profile, allows intergroup and cross-species comparisons.
The socio-matrix reloaded: from hierarchy to dominance profile in wild lemurs
Norscia, Ivan
2015-01-01
Dominance hierarchy influences the life quality of social animals, and its definition should in principle be based on the outcome of agonistic interactions. However, defining and comparing the dominance profile of social groups is difficult due to the different dominance measures used and because no one measure explains it all. We applied different analytical methods to winner-loser sociomatrices to determine the dominance profile of five groups of wild lemurs (species: Lemur catta, Propithecus verreauxi, and Eulemur rufus x collaris) from the Berenty forest (Madagascar). They are an excellent study model because they share the same habitat and an apparently similar dominance profile: linear hierarchy and female dominance. Data were collected over more than 1200 h of observation. Our approach included four steps: (1) by applying the binary dyadic dominance relationship method (I&SI) on either aggressions or supplant sociomatrices we verified whether hierarchy was aggression or submission based; (2) by calculating normalized David’s scores and measuring steepness from aggression sociomatrices we evaluated whether hierarchy was shallow or steep; (3) by comparing the ranking orders obtained with methods 1 and 2 we assessed whether hierarchy was consistent or not; and (4) by assessing triangle transitivity and comparing it with the linearity index and the level of group cohesion we determined if hierarchy was more or less cohesive. Our results show that L. catta groups have got a steep, consistent, highly transitive and cohesive hierarchy. P. verreauxi groups are characterized by a moderately steep and consistent hierarchy, with variable levels of triangle transitivity and cohesion. E. rufus x collaris group possesses a shallow and inconsistent hierarchy, with lower (but not lowest) levels of transitivity and cohesion. A multiple analytical approach on winner-loser sociomatrices other than leading to an in-depth description of the dominance profile, allows intergroup and cross-species comparisons. PMID:25653908
Fine particles on mars: Observations with the viking 1 lander cameras
Mutch, T.A.; Arvidson, R. E.; Binder, A.B.; Huck, F.O.; Levinthal, E.C.; Liebes, S.; Morris, E.C.; Nummedal, D.; Pollack, James B.; Sagan, C.
1976-01-01
Drifts of fine-grained sediment are present in the vicinity of the Viking 1 lander. Many drifts occur in the lees of large boulders. Morphologic analysis indicates that the last dynamic event was one of general deflation for at least some drifts. Particle cohesion implies that there is a distinct small-particle upturn in the threshold velocity-particle size curve; the apparent absence of the most easily moved particles (150 micrometers in diameter) may be due to their preferential transport to other regions or their preferential collisional destruction. A twilight rescan with lander cameras indicates a substantial amount of red dust with mean radius on the order of 1 micrometer in the atmosphere.
Fine particles on Mars: observations with the viking 1 lander cameras.
Mutch, T A; Arvidson, R E; Binder, A B; Huck, F O; Levinthal, E C; Liebes, S; Morris, E C; Nummedal, D; Pollack, J B; Sagan, C
1976-10-01
Drifts of fine-grained sediment are present in the vicinity of the Viking 1 lander. Many drifts occur in the lees of large boulders. Morphologic analysis indicates that the last dynamic event was one of general deflation for at least some drifts. Particle cohesion implies that there is a distinct small-particle upturn in the threshold velocity-particle size curve; the apparent absence of the most easily moved particles (150 micrometers in diameter) may be due to their preferential transport to other regions or their preferential collisional destruction. A twilight rescan with lander cameras indicates a substantial amount of red dust with mean radius on the order of 1 micrometer in the atmosphere.
Development of apparent viscosity test for hot-poured crack sealants.
DOT National Transportation Integrated Search
2008-11-01
Current crack sealant specifications focuses on utilizing simple empirical tests such as penetration, : resilience, flow, and bonding to cement concrete briquettes (ASTM D3405) to measure the ability of the material : to resist cohesive and adhesion ...
Learning from Simulation Games: Effects of Sociometric Grouping.
ERIC Educational Resources Information Center
Brand, Charles F.
1980-01-01
Study examined the influence of 141 fifth graders of two sociometric variables, mutual selection of playing partners and membership in a cohesive group, on learning from classroom simulation games. Although cognitive learning evidence existed, no effects of sociometric grouping were apparent. (CMV)
Effect of acetic acid on physical properties of pregelatinized wheat and corn starch gels.
Majzoobi, Mahsa; Kaveh, Zahra; Farahnaky, Asgar
2016-04-01
Pregelatinized starches are physically modified starches with ability to absorb water and increase viscosity at ambient temperature. The main purpose of this study was to determine how different concentrations of acetic acid (0, 500, 1000, 10,000 mg/kg) can affect functional properties of pregelatinized wheat and corn starches (PGWS and PGCS, respectively) produced by a twin drum drier. With increasing acetic acid following changes occurred for both samples; cold water solubility (at 25 °C) increased, water absorption and apparent cold water viscosity (at 25 °C) reduced, the smooth surface of the starch particles converted to an uneven surface as confirmed by scanning electron microscopy, cohesiveness, consistency and turbidity of the starch gels reduced while their syneresis increased. It was found that in presence of acetic acid, PGWS resulted in higher water absorption and apparent cold water viscosity and produced more cohesive and turbid gels with less syneresis compared to PGCS. Copyright © 2015 Elsevier Ltd. All rights reserved.
Using fluidized bed and flume experiments to quantify cohesion development from aging and drainage
USDA-ARS?s Scientific Manuscript database
Temporal variations in soil erosion resistance are often the result of a decrease in soil cohesion due to physical disruption followed by a regain of soil cohesion through a process analogous to a thixotropic sol-gel reaction also called aging, stabilization or consolidation. The goal of this study ...
Development of Improved Printed Wiring Board Inner Layer Adhesion.
1982-06-01
24722-49 A Oak-Atlantic 2048 Cohesive Failure in "C" Stage B Oak-Atlantic 1990 Cohesive Failure in "C" Stage C Mica 2018 Cohesive Failure In "C" Stage D...allowable resistance between test points for all IR measurements was 500 megohms. The results showed no blistering, measling , crazing or delaminatin due
A square-force cohesion model and its extraction from bulk measurements
NASA Astrophysics Data System (ADS)
Liu, Peiyuan; Lamarche, Casey; Kellogg, Kevin; Hrenya, Christine
2017-11-01
Cohesive particles remain poorly understood, with order of magnitude differences exhibited for prior, physical predictions of agglomerate size. A major obstacle lies in the absence of robust models of particle-particle cohesion, thereby precluding accurate prediction of the behavior of cohesive particles. Rigorous cohesion models commonly contain parameters related to surface roughness, to which cohesion shows extreme sensitivity. However, both roughness measurement and its distillation into these model parameters are challenging. Accordingly, we propose a ``square-force'' model, where cohesive force remains constant until a cut-off separation. Via DEM simulations, we demonstrate validity of the square-force model as surrogate of more rigorous models, when its two parameters are selected to match the two key quantities governing dense and dilute granular flows, namely maximum cohesive force and critical cohesive energy, respectively. Perhaps more importantly, we establish a method to extract the parameters in the square-force model via defluidization, due to its ability to isolate the effects of the two parameters. Thus, instead of relying on complicated scans of individual grains, determination of particle-particle cohesion from simple bulk measurements becomes feasible. Dow Corning Corporation.
Kim, Cheon-Jei; Kim, Hyun-Wook; Hwang, Ko-Eun; Song, Dong-Heon; Ham, Youn-Kyung; Choi, Ji-Hun; Kim, Young-Boong; Choi, Yun-Sang
2016-01-01
In this study, we investigated the effects of reducing fat levels from 30% to 25, 20, and 15% by substituting pork fat with water and pumpkin fiber (2%) on the quality of frankfurters compared with control. Decreasing the fat concentration from 30% to 15% significantly increased moisture content, redness of meat batter and frankfurter, cooking loss, and water exudation, and decreased fat content, energy value, pH, and lightness of meat batter and frankfurter, hardness, cohesiveness, gumminess, chewiness, and apparent viscosity. The addition of 2% pumpkin fiber was significantly increased moisture content, yellowness of meat batter and frankfurter, hardness, cohesiveness, gumminess, chewiness, and apparent viscosity, whereas reduced cooking loss and emulsion stability. The treatment of reduced-fat frankfurters formulated with 20 and 25% fat levels and with pumpkin fiber had sensory properties similar to the high-fat control frankfurters. The results demonstrate that when the reduced-fat frankfurter with 2% added pumpkin fiber and water replaces fat levels can be readily made with high quality and acceptable sensory properties.
Kim, Cheon-Jei; Kim, Hyun-Wook; Hwang, Ko-Eun; Song, Dong-Heon; Ham, Youn-Kyung; Choi, Ji-Hun
2016-01-01
In this study, we investigated the effects of reducing fat levels from 30% to 25, 20, and 15% by substituting pork fat with water and pumpkin fiber (2%) on the quality of frankfurters compared with control. Decreasing the fat concentration from 30% to 15% significantly increased moisture content, redness of meat batter and frankfurter, cooking loss, and water exudation, and decreased fat content, energy value, pH, and lightness of meat batter and frankfurter, hardness, cohesiveness, gumminess, chewiness, and apparent viscosity. The addition of 2% pumpkin fiber was significantly increased moisture content, yellowness of meat batter and frankfurter, hardness, cohesiveness, gumminess, chewiness, and apparent viscosity, whereas reduced cooking loss and emulsion stability. The treatment of reduced-fat frankfurters formulated with 20 and 25% fat levels and with pumpkin fiber had sensory properties similar to the high-fat control frankfurters. The results demonstrate that when the reduced-fat frankfurter with 2% added pumpkin fiber and water replaces fat levels can be readily made with high quality and acceptable sensory properties. PMID:27433101
Yan, Rihui; McKee, Bruce D.
2013-01-01
Cohesion between sister chromatids is mediated by cohesin and is essential for proper meiotic segregation of both sister chromatids and homologs. solo encodes a Drosophila meiosis-specific cohesion protein with no apparent sequence homology to cohesins that is required in male meiosis for centromere cohesion, proper orientation of sister centromeres and centromere enrichment of the cohesin subunit SMC1. In this study, we show that solo is involved in multiple aspects of meiosis in female Drosophila. Null mutations in solo caused the following phenotypes: 1) high frequencies of homolog and sister chromatid nondisjunction (NDJ) and sharply reduced frequencies of homolog exchange; 2) reduced transmission of a ring-X chromosome, an indicator of elevated frequencies of sister chromatid exchange (SCE); 3) premature loss of centromere pairing and cohesion during prophase I, as indicated by elevated foci counts of the centromere protein CID; 4) instability of the lateral elements (LE)s and central regions of synaptonemal complexes (SCs), as indicated by fragmented and spotty staining of the chromosome core/LE component SMC1 and the transverse filament protein C(3)G, respectively, at all stages of pachytene. SOLO and SMC1 are both enriched on centromeres throughout prophase I, co-align along the lateral elements of SCs and reciprocally co-immunoprecipitate from ovarian protein extracts. Our studies demonstrate that SOLO is closely associated with meiotic cohesin and required both for enrichment of cohesin on centromeres and stable assembly of cohesin into chromosome cores. These events underlie and are required for stable cohesion of centromeres, synapsis of homologous chromosomes, and a recombination mechanism that suppresses SCE to preferentially generate homolog crossovers (homolog bias). We propose that SOLO is a subunit of a specialized meiotic cohesin complex that mediates both centromeric and axial arm cohesion and promotes homolog bias as a component of chromosome cores. PMID:23874232
Yan, Rihui; McKee, Bruce D
2013-01-01
Cohesion between sister chromatids is mediated by cohesin and is essential for proper meiotic segregation of both sister chromatids and homologs. solo encodes a Drosophila meiosis-specific cohesion protein with no apparent sequence homology to cohesins that is required in male meiosis for centromere cohesion, proper orientation of sister centromeres and centromere enrichment of the cohesin subunit SMC1. In this study, we show that solo is involved in multiple aspects of meiosis in female Drosophila. Null mutations in solo caused the following phenotypes: 1) high frequencies of homolog and sister chromatid nondisjunction (NDJ) and sharply reduced frequencies of homolog exchange; 2) reduced transmission of a ring-X chromosome, an indicator of elevated frequencies of sister chromatid exchange (SCE); 3) premature loss of centromere pairing and cohesion during prophase I, as indicated by elevated foci counts of the centromere protein CID; 4) instability of the lateral elements (LE)s and central regions of synaptonemal complexes (SCs), as indicated by fragmented and spotty staining of the chromosome core/LE component SMC1 and the transverse filament protein C(3)G, respectively, at all stages of pachytene. SOLO and SMC1 are both enriched on centromeres throughout prophase I, co-align along the lateral elements of SCs and reciprocally co-immunoprecipitate from ovarian protein extracts. Our studies demonstrate that SOLO is closely associated with meiotic cohesin and required both for enrichment of cohesin on centromeres and stable assembly of cohesin into chromosome cores. These events underlie and are required for stable cohesion of centromeres, synapsis of homologous chromosomes, and a recombination mechanism that suppresses SCE to preferentially generate homolog crossovers (homolog bias). We propose that SOLO is a subunit of a specialized meiotic cohesin complex that mediates both centromeric and axial arm cohesion and promotes homolog bias as a component of chromosome cores.
Cohesive zone model for direct silicon wafer bonding
NASA Astrophysics Data System (ADS)
Kubair, D. V.; Spearing, S. M.
2007-05-01
Direct silicon wafer bonding and decohesion are simulated using a spectral scheme in conjunction with a rate-dependent cohesive model. The cohesive model is derived assuming the presence of a thin continuum liquid layer at the interface. Cohesive tractions due to the presence of a liquid meniscus always tend to reduce the separation distance between the wafers, thereby opposing debonding, while assisting the bonding process. In the absence of the rate-dependence effects the energy needed to bond a pair of wafers is equal to that needed to separate them. When rate-dependence is considered in the cohesive law, the experimentally observed asymmetry in the energetics can be explained. The derived cohesive model has the potential to form a bridge between experiments and a multiscale-modelling approach to understand the mechanics of wafer bonding.
Iraqi EFL Learners' Problems in Using Conjunctions as Cohesive Devices
ERIC Educational Resources Information Center
Darweesh, Abbas Deygan; Kadhim, Susan Abdul Hady
2016-01-01
Writing has been assumed to be the most problematic language skill for ESL/EFL learners (Ting, 2003; Ong, 2011) and even for native speakers (Norrish, 1983). Apparently, Prommas and Sinwongsuwat (2011:77) stated that writing is more challenging than speaking since in written communication there is no extra means of help in terms of nonverbal…
Social cohesion matters in health.
Chuang, Ying-Chih; Chuang, Kun-Yang; Yang, Tzu-Hsuan
2013-10-28
The concept of social cohesion has invoked debate due to the vagueness of its definition and the limitations of current measurements. This paper attempts to examine the concept of social cohesion, develop measurements, and investigate the relationship between social cohesion and individual health. This study used a multilevel study design. The individual-level samples from 29 high-income countries were obtained from the 2000 World Value Survey (WVS) and the 2002 European Value Survey. National-level social cohesion statistics were obtained from Organization of Economic Cooperation and Development datasets, World Development Indicators, and Asian Development Bank key indicators for the year 2000, and from aggregating responses from the WVS. In total 47,923 individuals were included in this study. The factor analysis was applied to identify dimensions of social cohesion, which were used as entities in the cluster analysis to generate a regime typology of social cohesion. Then, multilevel regression models were applied to assess the influences of social cohesion on an individual's self-rated health. Factor analysis identified five dimensions of social cohesion: social equality, social inclusion, social development, social capital, and social diversity. Then, the cluster analysis revealed five regimes of social cohesion. A multi-level analysis showed that respondents in countries with higher social inclusion, social capital, and social diversity were more likely to report good health above and beyond individual-level characteristics. This study is an innovative effort to incorporate different aspects of social cohesion. This study suggests that social cohesion was associated with individual self-rated after controlling individual characteristics. To achieve further advancement in population health, developed countries should consider policies that would foster a society with a high level of social inclusion, social capital, and social diversity. Future research could focus on identifying possible pathways by which social cohesion influences various health outcomes.
A thermodynamic analysis of propagating subcritical cracks with cohesive zones
NASA Technical Reports Server (NTRS)
Allen, David H.
1993-01-01
The results of the so-called energetic approach to fracture with particular attention to the issue of energy dissipation due to crack propagation are applied to the case of a crack with cohesive zone. The thermodynamic admissibility of subcritical crack growth (SCG) is discussed together with some hypotheses that lead to the derivation of SCG laws. A two-phase cohesive zone model for discontinuous crack growth is presented and its thermodynamics analyzed, followed by an example of its possible application.
Temporal pattern of soil matric suction in the unsaturated soil slope under different forest cover
NASA Astrophysics Data System (ADS)
Hayati, Elyas; Abdi, Ehsan; Mohseni Saravi, Mohsen; Nieber, John; Majnounian, Baris; Chirico, Giovanni
2017-04-01
In the vadose zone, usually, soils experience high matric suction during dry periods which results in a significant additional soil strength component (i.e., apparent cohesion) and thus plays a crucial role in the stability of unsaturated soil slopes. But, in the wet periods, when rain-water infiltrates into the soil, the matric suction of the soil dissipates partially or completely. It is a well-understood concept that vegetation can modify the hillslope hydrology and subsequent stability conditions by increasing soil matric suction through both interception of rainfall and depletion of soil water content via transpiration. Anthropogenic pressures, particularly clear-cutting and deforestation, affect many hydro-geomorphological processes including catchment and hillslope hydrology and stability. However, quantifying the changes in soil hydrologic conditions and the resulted stability of slopes due to these degrading activities remained an unresolved problem. To address this gap, a continuous measurement of soil water dynamics has been conducted at two adjacent hillslopes (one forested hillslope and one degraded hillslope) using PR2/6 profile probe for a 9-month period of time to demonstrate the forest cover-specific influence on the hillslope hydrology and stability during different seasons. The results have been then presented in terms of estimated soil matric suction to facilitate analyzing the resulted stability states due to the changes in soil water balance with time in the two studied hillslopes. The data were tested to check whether there are any differences between the forested and degraded hillslopes in terms of soil matric suction and augmented soil cohesion during different seasons. Finally, the response of soil hydrologic condition and the resulted slope stability for the 9-month period were analyzed and discussed for the different hillslopes.
Coagulation of particles in Saturn's rings - Measurements of the cohesive force of water frost
NASA Technical Reports Server (NTRS)
Hatzes, A. P.; Bridges, F.; Lin, D. N. C.; Sachtjen, S.
1991-01-01
Experimental data are presented on the sticking force of water ice particles which are indicative of the role that the cohesive properties of such particles could play in the dynamics of Saturn ring particles. Sticking forces are dependent on particle impact velocities; a 'Velcro' model is devised to describe the surface structure involved in sticking. The data indicate that below the critical impact velocity of about 0.03 cm/sec, particle cohesion always occurs. Due to the optical depth of micron-sized grains in the Saturn rings, particles are hypothesized to be coated with a layer of frost which will render cohesion an important ring-dynamics process.
Quantitative Procedure for Position Identity Definition.
1979-12-01
integrated into an effi- cient and cohesive team, are necessary for the sucessful performance of the mission of the 2-17 Department of the Army. Military...Headquarters (Ft Monroe) ROTC Group (TRADOC-Ft Knox) Large Post Headquarters (Ft Bragg) Recruiting Support Center (Cameron Service School (Engineer) Station...College (Ft Belvoir) (Ft Belvoir) Defense Mapping School (Ft Belvoir) The apparent distinction in Army directives between combat, combat support, and
Physical properties of muddy sediments from French Guiana
NASA Astrophysics Data System (ADS)
Caillaud, J.; Lesourd, L.; Philippe, S.; Gontharet, S.; Sarrazin, M.; Gardel, A.
2017-01-01
The North West migration of long and discontinuous mud banks along the French Guiana coast has been extensively studied during the past years, in particular with a large-scale vision, which consequently has integrated morpho and hydrodynamic data. The aims of the present paper were to use intrinsic sediment properties (grain-size, mineralogy, concentration, and cohesion) to (1) highlight the sedimentary conditions during the consolidation processes from fluid deposit to vegetation development, and (2) verify the apparent homogeneously derived sedimentary facies. Two intertidal transects, Macouria and Cayenne, were compared from the coast to offshore. Their altitude averages of 1 m and 2.8 m above mean sea level, respectively, were different enough to compare the influence of the hydrodynamic impact and emersion time on their sediment properties. The latter, i.e. grain size distribution, mineralogical content, mud concentration, and shear strength (cohesion), were determined from sampled surface sediments (first cm) and along sediment cores (20-30 cm depth) from each transect. A specific X-ray technique was applied to the whole core to differentiate clearly its thin layers. On both intertidal sites, the grain size dominated by the fine silt fraction (2-20 μm) and the bulk mineralogy characterized by five major minerals (quartz, feldspars, chlorite, illite, and kaolinite) appeared homogeneous along both transects and cores. In spite of this apparent uniformity of particle size and mineralogical parameters, as well as for visual observation along the core, high precision X-rays still showed a cyclic sedimentation at a micro-scale level. This cyclicity with intercalation of fine layers was related to distinct dynamic deposits marked by both tidal processes and hydrodynamic factors (swell propagation). The cohesion and concentration results were dependent on the topography, where high topography was characterized by sediments with high cohesion and concentration values, and vice versa. A comparison between these two parameters was done to define critical limits between soft and stiff muds, as well as unvegetated and colonized muds. The favorable intrinsic sedimentary properties for consolidation and colonization were also discussed according to the field observations and bibliographic data.
USDA-ARS?s Scientific Manuscript database
Seepage influences the erodibility of streambanks, streambeds, dams, and embankments. Usually the erosion rate of cohesive soils due to fluvial forces is computed using an excess shear stress model, dependent on two major soil parameters: the critical shear stress (tc) and the erodibility coefficie...
Cohesion enhancing effect of magnesium in aluminum grain boundary: A first-principles determination
DOE Office of Scientific and Technical Information (OSTI.GOV)
Zhang Shengjun; Freeman, Arthur J.; Department of Physics and Astronomy, Northwestern University, Evanston, Illinois 60208
2012-06-04
The effect of magnesium on grain boundary cohesion in aluminum was investigated by means of first-principles calculations using the Rice-Wang model [Rice and Wang, Mater. Sci. Eng. A 107, 23 (1989)]. It is demonstrated that magnesium is a cohesion enhancer with a potency of -0.11 eV/atom. It is further determined through electronic structure and bonding character analysis that the cohesion enhancing property of magnesium is due to a charge transfer mechanism which is unusually strong and overcomes the negative result of the size effect mechanism. Consistent with experimental results, this work clarifies the controversy and establishes that Mg segregation doesmore » not contribute to stress corrosion cracking in Al alloys.« less
Social cohesion matters in health
2013-01-01
Introduction The concept of social cohesion has invoked debate due to the vagueness of its definition and the limitations of current measurements. This paper attempts to examine the concept of social cohesion, develop measurements, and investigate the relationship between social cohesion and individual health. Methods This study used a multilevel study design. The individual-level samples from 29 high-income countries were obtained from the 2000 World Value Survey (WVS) and the 2002 European Value Survey. National-level social cohesion statistics were obtained from Organization of Economic Cooperation and Development datasets, World Development Indicators, and Asian Development Bank key indicators for the year 2000, and from aggregating responses from the WVS. In total 47,923 individuals were included in this study. The factor analysis was applied to identify dimensions of social cohesion, which were used as entities in the cluster analysis to generate a regime typology of social cohesion. Then, multilevel regression models were applied to assess the influences of social cohesion on an individual’s self-rated health. Results and discussion Factor analysis identified five dimensions of social cohesion: social equality, social inclusion, social development, social capital, and social diversity. Then, the cluster analysis revealed five regimes of social cohesion. A multi-level analysis showed that respondents in countries with higher social inclusion, social capital, and social diversity were more likely to report good health above and beyond individual-level characteristics. Conclusions This study is an innovative effort to incorporate different aspects of social cohesion. This study suggests that social cohesion was associated with individual self-rated after controlling individual characteristics. To achieve further advancement in population health, developed countries should consider policies that would foster a society with a high level of social inclusion, social capital, and social diversity. Future research could focus on identifying possible pathways by which social cohesion influences various health outcomes. PMID:24165541
NASA Astrophysics Data System (ADS)
Schwarz, Massimiliano; Cohen, Denis
2016-04-01
Rainfall is one of the major triggering factor of shallow landslide around the world. The increase of soil moisture in the soil influences the stability of a slope through the increase of soil bulk density, the reduction of soil apparent cohesion (due to suction stress), and the increase in pore water pressure.The spatio-temporal transformations of such properties of soil are know to be heterogeneous and under constant change. For instance, there may be a condition where, in cracked clay-soil, water, during a rain event, produces a rapid increase of pore water pressure along preferential flow-paths (crack or roots), while soil moisture and suction within the soil matrix change minimally. An another site in a sandy soil, the situation might be very different where the increase of soil moisture and pore water pressure, and the decrease of soil suction take place more or less simultaneously across the entire soil profile. In both of these cases topography plays a major role in determining the accumulation of water along the slope through different subsurface flows intensities and directions. In many documented cases in the Alps, shallow landslides may also be triggered by the punctual exfiltration of water from bedrock or weathered geological strata. The hydro-geological characteristics of the catchment control this mechanism. These different situations aim to give an idea of the large spectrum of hydrological triggering conditions of shallow landslides. The heterogeneities of these hydrological conditions represent a difficult issue in modeling shallow landslide triggering mechanisms. In the simplest models, hydrology is assumed to influence changes in pore water pressure only, mostly using one dimensional vertical infiltration models. More advanced models consider changes in apparent cohesion due to changes in soil moisture or include more complex hydrological models to simulate water flow and distribution during a rainfall event. However, most models at the regional scale rely on the infinite slope assumption for stability calculations and on continuous hydrological properties of the soil. The objective of the present study is to investigate the influence of non-continuos hydrological features (such as ephemeral springs) on the triggering mechanisms of shallow landslides using a discrete element model (SOSlope) in which the stress-strain behavior of soil is explicitly considered. The application of a stress-strain calculation allows for the simulation of local versus global loading due to hydrological processes. In particular, this study investigates the effects of different types of hydrological loading on the force redistribution on a slope associated with local displacements and following failures of soil masses. Strength and stiffness of soil are considered heterogeneous and are calculated based on the assumption of root distributions within a forested hillslope.
Granulation of snow: From tumbler experiments to discrete element simulations
NASA Astrophysics Data System (ADS)
Steinkogler, Walter; Gaume, Johan; Löwe, Henning; Sovilla, Betty; Lehning, Michael
2015-06-01
It is well known that snow avalanches exhibit granulation phenomena, i.e., the formation of large and apparently stable snow granules during the flow. The size distribution of the granules has an influence on flow behavior which, in turn, affects runout distances and avalanche velocities. The underlying mechanisms of granule formation are notoriously difficult to investigate within large-scale field experiments, due to limitations in the scope for measuring temperatures, velocities, and size distributions. To address this issue we present experiments with a concrete tumbler, which provide an appropriate means to investigate granule formation of snow. In a set of experiments at constant rotation velocity with varying temperatures and water content, we demonstrate that temperature has a major impact on the formation of granules. The experiments showed that granules only formed when the snow temperature exceeded -1∘C. No evolution in the granule size was observed at colder temperatures. Depending on the conditions, different granulation regimes are obtained, which are qualitatively classified according to their persistence and size distribution. The potential of granulation of snow in a tumbler is further demonstrated by showing that generic features of the experiments can be reproduced by cohesive discrete element simulations. The proposed discrete element model mimics the competition between cohesive forces, which promote aggregation, and impact forces, which induce fragmentation, and supports the interpretation of the granule regime classification obtained from the tumbler experiments. Generalizations, implications for flow dynamics, and experimental and model limitations as well as suggestions for future work are discussed.
NASA Astrophysics Data System (ADS)
Legoix, Léonard; Milhé, Mathieu; Gatumel, Cendrine; Berthiaux, Henri
2017-06-01
An original methodology for studying powder flow in a cylindrical convective blender has been developed. A free-flowing and a cohesive powder were studied, at a fixed stirring speed, in rolling regime. For both powders, three apparent flow mechanisms were evidenced: convection in the volume swept by the blades, diffusion/shearing between the agitated zone and the stagnant one, as well as in the stagnant zone itself, and avalanches at the powder bed surface between agitated and stagnant zones. After defining six zones in the blender, tracing experiments were carried out by placing appropriate tracers in different starting zones and sampling the whole bed at different stirring times, which lead to mixing kinetics of the powders into themselves. A Markov chains model of the blender allowed the quantification of the three mechanisms respective magnitude by fitting the experimental data. This simple model has a good agreement with the free-flowing powder data, but is not able to represent well the observations for the cohesive powder. Bed consolidation should probably be taken into account for this kind of powders and thus a linear Markov model is not sufficient.
Investigating the settling dynamics of cohesive silt particles with particle-resolving simulations
NASA Astrophysics Data System (ADS)
Sun, Rui; Xiao, Heng; Sun, Honglei
2018-01-01
The settling of cohesive sediment is ubiquitous in aquatic environments, and the study of the settling process is important for both engineering and environmental reasons. In the settling process, the silt particles show behaviors that are different from non-cohesive particles due to the influence of inter-particle cohesive force. For instance, the flocs formed in the settling process of cohesive silt can loosen the packing, and thus the structural densities of cohesive silt beds are much smaller than that of non-cohesive sand beds. While there is a consensus that cohesive behaviors depend on the characteristics of sediment particles (e.g., Bond number, particle size distribution), little is known about the exact influence of these characteristics on the cohesive behaviors. In addition, since the cohesive behaviors of the silt are caused by the inter-particle cohesive forces, the motions of and the contacts among silt particles should be resolved to study these cohesive behaviors in the settling process. However, studies of the cohesive behaviors of silt particles in the settling process based on particle-resolving approach are still lacking. In the present work, three-dimensional settling process is investigated numerically by using CFD-DEM (Computational Fluid Dynamics-Discrete Element Method). The inter-particle collision force, the van der Waals force, and the fluid-particle interaction forces are considered. The numerical model is used to simulate the hindered settling process of silt based on the experimental setup in the literature. The results obtained in the simulations, including the structural densities of the beds, the characteristic lines, and the particle terminal velocity, are in good agreement with the experimental observations in the literature. To the authors' knowledge, this is the first time that the influences of non-dimensional Bond number and particle polydispersity on the structural densities of silt beds have been investigated separately. The results demonstrate that the cohesive behavior of silt in the settling process is attributed to both the cohesion among silt particles themselves and the particle polydispersity. To guide to the macro-scale modeling of cohesive silt sedimentation, the collision frequency functions obtained in the numerical simulations are also presented based on the micromechanics of particles. The results obtained by using CFD-DEM indicate that the binary collision theory over-estimated the particle collision frequency in the flocculation process at high solid volume fraction.
Geotechnical properties of municipal solid waste at different phases of biodegradation
DOE Office of Scientific and Technical Information (OSTI.GOV)
Reddy, Krishna R., E-mail: kreddy@uic.edu; Hettiarachchi, Hiroshan, E-mail: hiroshan@ltu.edu; Gangathulasi, Janardhanan, E-mail: jganga2@uic.edu
Highlights: > Degraded synthetic municipal solid waste (MSW) anaerobically in controlled bench-scale reactors. > Performed laboratory tests to determine geotechnical properties of MSW at different phases of degradation. > Hydraulic conductivity decreased by two orders of magnitude due to degradation. > Compression ratio reduced from 0.34 for initial fresh waste to 0.15 for the mostly degraded waste. > Friction angle reduced, but cohesion increased with degradation. - Abstract: This paper presents the results of laboratory investigation conducted to determine the variation of geotechnical properties of synthetic municipal solid waste (MSW) at different phases of degradation. Synthetic MSW samples were preparedmore » based on the composition of MSW generated in the United States and were degraded in bioreactors with leachate recirculation. Degradation of the synthetic MSW was quantified based on the gas composition and organic content, and the samples exhumed from the bioreactor cells at different phases of degradation were tested for the geotechnical properties. Hydraulic conductivity, compressibility and shear strength of initial and degraded synthetic MSW were all determined at constant initial moisture content of 50% on wet weight basis. Hydraulic conductivity of synthetic MSW was reduced by two orders of magnitude due to degradation. Compression ratio was reduced from 0.34 for initial fresh waste to 0.15 for the mostly degraded waste. Direct shear tests showed that the fresh and degraded synthetic MSW exhibited continuous strength gain with increase in horizontal deformation, with the cohesion increased from 1 kPa for fresh MSW to 16-40 kPa for degraded MSW and the friction angle decreased from 35{sup o} for fresh MSW to 28{sup o} for degraded MSW. During the triaxial tests under CU condition, the total strength parameters, cohesion and friction angle, were found to vary from 21 to 57 kPa and 1{sup o} to 9{sup o}, respectively, while the effective strength parameters, cohesion and friction angle varied from 18 to 56 kPa and from 1{sup o} to 11{sup o}, respectively. Similar to direct shear test results, as the waste degrades an increase in cohesion and slight decrease in friction angle was observed. Decreased friction angle and increased cohesion with increased degradation is believed to be due to the highly cohesive nature of the synthetic MSW. Variation of synthetic MSW properties from this study also suggests that significant changes in geotechnical properties of MSW can occur due to enhanced degradation induced by leachate recirculation.« less
Lee, Inhwa; Kim, Gun Woo; Yang, Minyang; Kim, Taek-Soo
2016-01-13
Conductive polymer poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) ( PSS) has attracted significant attention as a hole transport and electrode layer that substitutes metal electrodes in flexible organic devices. However, its weak cohesion critically limits the reliable integration of PSS in flexible electronics, which highlights the importance of further investigation of the cohesion of PSS. Furthermore, the electrical conductivity of PSS is insufficient for high current-carrying devices such as organic photovoltaics (OPVs) and organic light emitting diodes (OLEDs). In this study, we improve the cohesion and electrical conductivity through adding dimethyl sulfoxide (DMSO), and we demonstrate the significant changes in the properties that are dependent on the wt % of DMSO. In particular, with the addition of 3 wt % DMSO, the maximum enhancements for cohesion and electrical conductivity are observed where the values increase by 470% and 6050%, respectively, due to the inter-PEDOT bridging mechanism. Furthermore, when OLED devices using the PSS films are fabricated using the 3 wt % DMSO, the display exhibits 18% increased current efficiency.
Mechanics of Sister Chromatids studied with a Polymer Model
NASA Astrophysics Data System (ADS)
Zhang, Yang; Isbaner, Sebastian; Heermann, Dieter
2013-10-01
Sister chromatid cohesion denotes the phenomenon that sister chromatids are initially attached to each other in mitosis to guarantee the error-free distribution into the daughter cells. Cohesion is mediated by binding proteins and only resolved after mitotic chromosome condensation is completed. However, the amount of attachement points required to maintain sister chromatid cohesion while still allowing proper chromosome condensation is not known yet. Additionally the impact of cohesion on the mechanical properties of chromosomes also poses an interesting problem. In this work we study the conformational and mechanical properties of sister chromatids by means of computer simulations. We model both protein-mediated cohesion between sister chromatids and chromosome condensation with a dynamic binding mechanisms. We show in a phase diagram that only specific link concentrations lead to connected and fully condensed chromatids that do not intermingle with each other nor separate due to entropic forces. Furthermore we show that dynamic bonding between chromatids decrease the Young's modulus compared to non-bonded chromatids.
Rheology of granular materials composed of crushable particles.
Nguyen, Duc-Hanh; Azéma, Émilien; Sornay, Philippe; Radjaï, Farhang
2018-04-11
We investigate sheared granular materials composed of crushable particles by means of contact dynamics simulations and the bonded-cell model for particle breakage. Each particle is paved by irregular cells interacting via cohesive forces. In each simulation, the ratio of the internal cohesion of particles to the confining pressure, the relative cohesion, is kept constant and the packing is subjected to biaxial shearing. The particles can break into two or more fragments when the internal cohesive forces are overcome by the action of compressive force chains between particles. The particle size distribution evolves during shear as the particles continue to break. We find that the breakage process is highly inhomogeneous both in the fragment sizes and their locations inside the packing. In particular, a number of large particles never break whereas a large number of particles are fully shattered. As a result, the packing keeps the memory of its initial particle size distribution, whereas a power-law distribution is observed for particles of intermediate size due to consecutive fragmentation events whereby the memory of the initial state is lost. Due to growing polydispersity, dense shear bands are formed inside the packings and the usual dilatant behavior is reduced or cancelled. Hence, the stress-strain curve no longer passes through a peak stress, and a progressive monotonic evolution towards a pseudo-steady state is observed instead. We find that the crushing rate is controlled by the confining pressure. We also show that the shear strength of the packing is well expressed in terms of contact anisotropies and force anisotropies. The force anisotropy increases while the contact orientation anisotropy declines for increasing internal cohesion of the particles. These two effects compensate each other so that the shear strength is nearly independent of the internal cohesion of particles.
Schmidt, K.M.; Roering, J.J.; Stock, J.D.; Dietrich, W.E.; Montgomery, D.R.; Schaub, T.
2001-01-01
Decades of quantitative measurement indicate that roots can mechanically reinforce shallow soils in forested landscapes. Forests, however, have variations in vegetation species and age which can dominate the local stability of landslide-initiation sites. To assess the influence of this variability on root cohesion we examined scarps of landslides triggered during large storms in February and November of 1996 in the Oregon Coast Range and hand-dug soil pits on stable ground. At 41 sites we estimated the cohesive reinforcement to soil due to roots by determining the tensile strength, species, depth, orientation, relative health, and the density of roots ???1 mm in diameter within a measured soil area. We found that median lateral root cohesion ranges from 6.8-23.2 kPa in industrial forests with significant understory and deciduous vegetation to 25.6-94.3 kPa in natural forests dominated by coniferous vegetation. Lateral root cohesion in clearcuts is uniformly ???10 kPa. Some 100-year-old industrial forests have species compositions, lateral root cohesion, and root diameters that more closely resemble 10-year-old clearcuts than natural forests. As such, the influence of root cohesion variability on landslide susceptibility cannot be determined solely from broad age classifications or extrapolated from the presence of one species of vegetation. Furthermore, the anthropogenic disturbance legacy modifies root cohesion for at least a century and should be considered when comparing contemporary landslide rates from industrial forests with geologic background rates.
NASA Astrophysics Data System (ADS)
Nilfouroushan, F.; Pysklywec, R.; Cruden, S.
2009-05-01
Cohesionless or very low cohesion granular materials are widely used in analogue/physical models to simulate brittle rocks in the upper crust. Selection of materials with appropriate cohesion values in such models is important for the simulation of the dynamics of brittle rock deformation in nature. Uncertainties in the magnitude of cohesion (due to measurement errors, extrapolations at low normal stresses, or model setup) in laboratory experiments can possibly result in misinterpretation of the styles and mechanisms of deformation in natural fold-and thrust belts. We ran a series of 2-D numerical models to investigate systematically the effect of cohesion uncertainties on the evolution of models of fold-and-thrust belts. The analyses employ SOPALE, a geodynamic code based on the arbitrary Lagrangian-Eulerian (ALE) finite element method. Similar to analogue models, the material properties of sand and transparent silicone (PDMS) are used to simulate brittle and viscous behaviors of upper crustal rocks. The suite of scaled brittle and brittle-viscous numerical experiments have the same initial geometry but the cohesion value of the brittle layers is increased systematically from 0 to 100 Pa. The stress and strain distribution in different sets of models with different cohesion values are compared and analyzed. The kinematics and geometry of thrust wedges including the location and number of foreland- and hinterland- verging thrust faults, pop-up structures, tapers and topography are also explored and their sensitivity to cohesion value is discussed.
Transport and deposition of cohesive pharmaceutical powders in human airway
NASA Astrophysics Data System (ADS)
Wang, Yuan; Chu, Kaiwei; Yu, Aibing
2017-06-01
Pharmaceutical powders used in inhalation therapy are in the size range of 1-5 microns and are usually cohesive. Understanding the cohesive behaviour of pharmaceutical powders during their transportation in human airway is significant in optimising aerosol drug delivery and targeting. In this study, the transport and deposition of cohesive pharmaceutical powders in a human airway model is simulated by a well-established numerical model which combines computational fluid dynamics (CFD) and discrete element method (DEM). The van der Waals force, as the dominant cohesive force, is simulated and its influence on particle transport and deposition behaviour is discussed. It is observed that even for dilute particle flow, the local particle concentration in the oral to trachea region can be high and particle aggregation happens due to the van der Waals force of attraction. It is concluded that the deposition mechanism for cohesive pharmaceutical powders, on one hand, is dominated by particle inertial impaction, as proven by previous studies; on the other hand, is significantly affected by particle aggregation induced by van der Waals force. To maximum respiratory drug delivery efficiency, efforts should be made to avoid pharmaceutical powder aggregation in human oral-to-trachea airway.
NASA Technical Reports Server (NTRS)
Hoewer, Daniel; Lerch, Bradley A.; Bednarcyk, Brett A.; Pineda, Evan Jorge; Reese, Stefanie; Simon, Jaan-Willem
2017-01-01
A new cohesive zone traction-separation law, which includes the effects of fiber bridging, has been developed, implemented with a finite element (FE) model, and applied to simulate the delamination between the facesheet and core of a composite honeycomb sandwich panel. The proposed traction-separation law includes a standard initial cohesive component, which accounts for the initial interfacial stiffness and energy release rate, along with a new component to account for the fiber bridging contribution to the delamination process. Single cantilever beam tests on aluminum honeycomb sandwich panels with carbon fiber reinforced polymer facesheets were used to characterize and evaluate the new formulation and its finite element implementation. These tests, designed to evaluate the mode I toughness of the facesheet to core interface, exhibited significant fiber bridging and large crack process zones, giving rise to a concave downward concave upward pre-peak shape in the load-displacement curve. Unlike standard cohesive formulations, the proposed formulation captures this observed shape, and its results have been shown to be in excellent quantitative agreement with experimental load-displacement and apparent critical energy release rate results, representative of a payload fairing structure, as well as local strain fields measured with digital image correlation.
Magee, Joe C; Tiedens, Larissa Z
2006-12-01
In three studies, observers based inferences about the cohesiveness and common fate of groups on the emotions expressed by group members. The valence of expressions affected cohesiveness inferences, whereas the consistency of expressions affected inferences of whether members have common fate. These emotion composition effects were stronger than those due to the race or sex composition of the group. Furthermore, the authors show that emotion valence and consistency are differentially involved in judgments about the degree to which the group as a whole was responsible for group performance. Finally, it is demonstrated that valence-cohesiveness effects are mediated by inferences of interpersonal liking and that consistency-common fate effects are mediated by inferences of psychological similarity. These findings have implications for the literature on entitativity and regarding the function of emotions in social contexts.
Cohesion, Cracking, Dilation, and Flow -- Rheological Behavior of Cohesive Pharmaceutical Powders
NASA Astrophysics Data System (ADS)
Muzzio, Fernando
2007-03-01
Cohesive powders can be loosely defined as systems where the attractive forced between particles exceed the average particle weight. Cohesive powder flow is interesting from a wide range of reasons. Their main characteristic, intermittence, is evidenced both in the interruption of flow out of hoppers (a mundane issue causing great annoyance to industrial practitioners) and in the sudden avalanching of snow and dirt that has terrified and terrified mankind since the dawn of time. At the present time, our ability to predict either of these phenomena (and many more involving cohesive powders) is very limited, primarily due to an incomplete understanding of their constitutive behavior. To wit, consider just a simple fact: a flowing powder never has constant density. Equations describing the relationship between velocity, shear, stress, and density are rudimentary at best. Computational and experimental approaches for characterizing flow behavior are in their infancy. In this talk, I will describe some recent progress achieved at Rutgers by our group. New instruments have been developed to determine simultaneously powder density and cohesive flow effects. Extensive measurements have been carried out focusing on pharmaceutical blends. These results have been used to fine-tune computational models that accurately predict dilation, flow in drums, and flow in hoppers. Impact of these observations for pharmaceutical manufacturing applications will be discussed in some detail.
Disaggregation of small, cohesive rubble pile asteroids due to YORP
NASA Astrophysics Data System (ADS)
Scheeres, D. J.
2018-04-01
The implication of small amounts of cohesion within relatively small rubble pile asteroids is investigated with regard to their evolution under the persistent presence of the YORP effect. We find that below a characteristic size, which is a function of cohesive strength, density and other properties, rubble pile asteroids can enter a "disaggregation phase" in which they are subject to repeated fissions after which the formation of a stabilizing binary system is not possible. Once this threshold is passed rubble pile asteroids may be disaggregated into their constituent components within a finite time span. These constituent components will have their own spin limits - albeit potentially at a much higher spin rate due to the greater strength of a monolithic body. The implications of this prediction are discussed and include modification of size distributions, prevalence of monolithic bodies among meteoroids and the lifetime of small rubble pile bodies in the solar system. The theory is then used to place constraints on the strength of binary asteroids characterized as a function of their type.
Active cell-matrix coupling regulates cellular force landscapes of cohesive epithelial monolayers
NASA Astrophysics Data System (ADS)
Zhao, Tiankai; Zhang, Yao; Wei, Qiong; Shi, Xuechen; Zhao, Peng; Chen, Long-Qing; Zhang, Sulin
2018-03-01
Epithelial cells can assemble into cohesive monolayers with rich morphologies on substrates due to competition between elastic, edge, and interfacial effects. Here we present a molecularly based thermodynamic model, integrating monolayer and substrate elasticity, and force-mediated focal adhesion formation, to elucidate the active biochemical regulation over the cellular force landscapes in cohesive epithelial monolayers, corroborated by microscopy and immunofluorescence studies. The predicted extracellular traction and intercellular tension are both monolayer size and substrate stiffness dependent, suggestive of cross-talks between intercellular and extracellular activities. Our model sets a firm ground toward a versatile computational framework to uncover the molecular origins of morphogenesis and disease in multicellular epithelia.
Cohesive detachment of an elastic pillar from a dissimilar substrate
NASA Astrophysics Data System (ADS)
Fleck, N. A.; Khaderi, S. N.; McMeeking, R. M.; Arzt, E.
The adhesion of micron-scale surfaces due to intermolecular interactions is a subject of intense interest spanning electronics, biomechanics and the application of soft materials to engineering devices. The degree of adhesion is sensitive to the diameter of micro-pillars in addition to the degree of elastic mismatch between pillar and substrate. Adhesion-strength-controlled detachment of an elastic circular cylinder from a dissimilar substrate is predicted using a Dugdale-type of analysis, with a cohesive zone of uniform tensile strength emanating from the interface corner. Detachment initiates when the opening of the cohesive zone attains a critical value, giving way to crack formation. When the cohesive zone size at crack initiation is small compared to the pillar diameter, the initiation of detachment can be expressed in terms of a critical value Hc of the corner stress intensity. The estimated pull-off force is somewhat sensitive to the choice of stick/slip boundary condition used on the cohesive zone, especially when the substrate material is much stiffer than the pillar material. The analysis can be used to predict the sensitivity of detachment force to the size of pillar and to the degree of elastic mismatch between pillar and substrate.
Behavioural Contagion Explains Group Cohesion in a Social Crustacean.
Broly, Pierre; Deneubourg, Jean-Louis
2015-06-01
In gregarious species, social interactions maintain group cohesion and the associated adaptive values of group living. The understanding of mechanisms leading to group cohesion is essential for understanding the collective dynamics of groups and the spatio-temporal distribution of organisms in environment. In this view, social aggregation in terrestrial isopods represents an interesting model due to its recurrence both in the field and in the laboratory. In this study, and under a perturbation context, we experimentally tested the stability of groups of woodlice according to group size and time spent in group. Our results indicate that the response to the disturbance of groups decreases with increases in these two variables. Models neglecting social effects cannot reproduce experimental data, attesting that cohesion of aggregation in terrestrial isopods is partly governed by a social effect. In particular, models involving calmed and excited individuals and a social transition between these two behavioural states more accurately reproduced our experimental data. Therefore, we concluded that group cohesion (and collective response to stimulus) in terrestrial isopods is governed by a transitory resting state under the influence of density of conspecifics and time spent in group. Lastly, we discuss the nature of direct or indirect interactions possibly implicated.
Failure modes and conditions of a cohesive, spherical body due to YORP spin-up
NASA Astrophysics Data System (ADS)
Hirabayashi, Masatoshi
2015-12-01
This paper presents transition of the failure mode of a cohesive, spherical body due to The Yarkovsky-O'Keefe-Radzievskii-Paddack (YORP) spin-up. On the assumption that the distribution of materials in the body is homogeneous, failed regions first appearing in the body at different spin rates are predicted by comparing the yield condition of an elastic stress in the body. It is found that as the spin rate increases, the locations of the failed regions move from the equatorial surface to the central region. To avoid such failure modes, the body should have higher cohesive strength. The results by this model are consistent with those by a plastic finite element model. Then, this model and a two-layered-cohesive model first proposed by Hirabayashi et al. are used to classify possible evolution and disruption of a spherical body. There are three possible pathways to disruption. First, because of a strong structure, failure of the central region is dominant and eventually leads to a breakup into multiple components. Secondly, a weak surface and a weak interior make the body oblate. Thirdly, a strong internal core prevents the body from failing and only allows surface shedding. This implies that observed failure modes may highly depend on the internal structure of an asteroid, which could provide crucial information for giving constraints on the physical properties.
Griffith, James
2015-01-01
A behavioral health concern for the US military has been suicide, largely due to its increased prevalence in the last several years during US involvement in the Iraq and Afghanistan wars. Using hierarchical linear modeling (HLM), the present study examined relationships among combat exposure, postdeployment stressors, social support, and unit cohesion. Survey data were obtained from 4,567 soldiers who were members of 50 company-sized units. At the individual level, combat exposure and postdeployment stressors were associated with suicidal thoughts. Postdeployment social support was associated with fewer suicidal thoughts. There was no evidence of the stress-buffering effect of social support. At the group level, reduced risk for suicidal thoughts was associated with units having higher than average cohesion. Reduced risk for suicidal thoughts in conjunction with combat experiences was observed in units having higher than average cohesion, though not reaching a traditional level of statistical significance.
NASA Astrophysics Data System (ADS)
Hauer, Michél; Henkel, Knuth Michael; Krebs, Sebastian; Kroemmer, Werner
2018-01-01
The highly cavitation erosion-resistant propeller alloys CuAl9Ni5Fe4Mn (Ni-Al-Bronze) and CuMn13Al8Fe3Ni2 (Mn-Al-Bronze) were arc-sprayed using a mixture of nitrogen and 2% of hydrogen as atomizing gas and different traverse speeds. The objective was to identify the influences of the different spraying conditions, such as temperature regime and melting loss, on the resulting residual stress states and coating properties. Residual stresses were measured by the incremental hole-drilling method using ESPI. Temperature measurements were carried out by thermographic imaging. Microstructural, chemical and mechanical analyses were realized to examine adhesive and cohesive properties. Additionally, the cavitation erosion behavior was investigated to analyze cohesive coating properties. The spraying process itself was improved, which was apparent by mainly enhanced deposition efficiency and reduced surface temperatures. The amount of oxides and pores as well as the melting loss of alloying elements were reduced. Moreover, an increased cavitation erosion resistance and thus coating cohesion as well as less residual stresses were identified. The change in atomizing gas diminished the impact of the quenching stresses on the coating properties. In contrast, the adhesive strength, Young's moduli and partially the hardness were slightly reduced. With regard to materials, Ni-Al-Bronze revealed superior coating properties in comparison with Mn-Al-Bronze.
Effect of geometric nonlinearity on acoustic modulation
NASA Astrophysics Data System (ADS)
Warnemuende, Kraig; Wu, Hwai-Chung
2005-05-01
Non-linear nondestructive testing is different from linear acoustic in that it correlates the presence and characteristics of a defect with acoustical signals whose frequencies differ from the frequencies of the emitted probe signal. The difference in frequencies between the probe signal and the resulting frequencies is due to a nonlinear transformation of the probe signal as it passes through a defect. Under acoustic interrogation due to longitudinal waves, as the compression phase passes the defect the two sides of the interface are in direct contact and the contact area increases. Similarly, the tensile phase passes through the defect, the two sides separate and the contact area decreases, thereby modulating the signal amplitude. The contact area depends on the roughness of the surface and on the magnitude of the cohesive forces that arise from the small crack openings. Such cohesive forces may be attributed to aggregate interlock (in plain concrete), fiber bridging (in fiber reinforced concrete) or both. In this paper, the frequency shifts of the probe elastic wave will be analytically related to the roughness and varying cohesive forces of the crack-like defect.
Educational Brief: Using Space for a Better Foundation on Earth Mechanics of Granular Materials
NASA Technical Reports Server (NTRS)
Dooling, Dave (Editor)
2002-01-01
Soils are three-phase composite materials that consist of soil, solid particles, and voids filled with water and/or air. Based on the particle-size distribution, they are generally classified as fine-grained (clays and plastic silts) and coarse-grained soils (nonplastic silts, sand, and gravel). Soil's resistance to external loadings is mainly derived from friction between particles and cohesion. Friction resistance is due to particles' surface-to-surface friction, interlocking, crushing, rearrangement, and dilation (or expansion) during shearing. Cohesion can be due to chemical cementation between particles, electrostatic and electromagnetic forces, and soil-water reaction and equilibrium. The basic factor responsible for the strength of coarse-grained soils is friction. Cohesion can be ignored. This educational brief focuses on measuring shear strength of sands (typical example of coarse-grained soils) where, for the same material, packing density is a main factor to be considered when one asks about the shear strength value. As the external load is applied, the soil's resistance is attained through shearing resistance, which causes the soil volume to increase (expand) or decrease (compress) depending on the initial packing density.
Influence of Environmental Factors on Vibrio spp. in Coastal Ecosystems.
Johnson, Crystal N
2015-06-01
Various studies have examined the relationships between vibrios and the environmental conditions surrounding them. However, very few reviews have compiled these studies into cohesive points. This may be due to the fact that these studies examine different environmental parameters, use different sampling, detection, and enumeration methodologies, and occur in diverse geographic locations. The current article is one approach to compile these studies into a cohesive work that assesses the importance of environmental determinants on the abundance of vibrios in coastal ecosystems.
Kim, Yeon-Pyo; Kim, Sun; Joh, Ju-Youn
2015-06-01
South Korea's low birth rate, aging society, and female migration to urban areas due to industrialization have caused an accelerated inflow of Asian female immigrants into Korea to marry Korean men, especially in rural areas. This study was performed to determine how family function of multicultural families changes over time and what factors affect the changes in family function of multicultural families. The study subjects were 62 Asian immigrant women married to South Korean men living in South Korea. In a 1st wave study in August 2008, the socioeconomic factors and Family Adaptability and Cohesion Scale III (FACES III) scores were measured. A 3-year follow-up study was then conducted in August 2011, and the results were compared with the 1st wave study results. The mean family adaptability score was 24.6 in the 1st wave study and 26.1 at the 3-year follow-up. The average family cohesion score was 31.0 in the 1st wave study and 36.7 at the 3-year follow-up. There was a statistically significant increase in family cohesion after 3 years (P < 0.001). In multiple regression analysis, age difference between husband and wife (P = 0.019) and subjective SES (P < 0.001) were found to be significantly correlated with positive changes of cohesion scores. Family adaptability did not change over time; however, conversely, family cohesion increased. The age difference between husband and wife and the subjective SES had a positive association with the changes in family cohesion. Copyright © 2013 Wiley Publishing Asia Pty Ltd.
Embedded Cohesive Elements (ECE) Approach to the Simulation of Spall Fracture Experiment
NASA Astrophysics Data System (ADS)
Bonora, Nicola; Esposito, Luca; Ruggiero, Andrew
2007-06-01
Discrepancies between the calculated and observed velocity vs time plot, relatively to the spall signal portion in terms of both signal amplitude and frequency, in numerical simulations of flyer plate impact test are usually shown. These are often ascribed either to material model or the numerical scheme used. Bonora et al. (2003 )[Bonora N., Ruggiero A. and Milella P.P., 2003, Fracture energy effect on spall signal, Proc. of 13^th APS SCCM03, Portland, USA] showed that, for ductile metals, these differences can be the imputed to the dissipation process during fracturing due to the viscous separation of spall fracture plane surfaces. In this work that concept has been further developed implementing an embedded cohesive elements (ECE) technology into FEM. The ECE method consists in embedding cohesive elements (normal and shear forces only) into standard isoparametric 2D or 3D FEM continuum elements. The cohesive elements remain silent and inactive until the continuum element fails. At failure, the continuum element is removed while the ECE becomes active until the separation energy is dissipated. Here, the methodology is presented and applied to simulate soft spall in ductile metals such as OHFC copper. Results of parametric study on mesh size and cohesive law shape effect are presented.
Social cohesion, social participation and HIV testing among men who have sex with men in Swaziland.
Grover, Elise; Grosso, Ashley; Ketende, Sosthenes; Kennedy, Caitlin; Fonner, Virginia; Adams, Darrin; Sithole, Bhekie; Mnisi, Zandile; Maziya, Sibusiso Lulu; Baral, Stefan
2016-01-01
Social cohesion and social participation are social factors that may help reduce HIV risks and optimize health-seeking behaviors. We examined the association between these factors and HIV testing in the last 12 months among men who have sex with men (MSM) in Swaziland using a cross-sectional survey conducted with 326 men, 18 years of age or older reporting having sex with another man in the last 12 months. Social capital analyses included measures of social cohesion and social participation. The social cohesion measurement scale was created through exploratory factor analysis using polychoric correlations to determine unidimensionality and Cronbach's Alpha to assess internal consistency. The measurement scale was divided at the 25th and 75th percentiles using "high," "medium" and "low" levels of social cohesion for between-group comparisons. The social participation index included four questions regarding participation, resulting in a participation index ranging from 0 to 4. In the final multivariate logistic regression model, an increase in the level of social participation was found to be significantly associated with HIV testing in the last 12 months, adjusting for age, income, reporting a casual partner, family exclusion and rejection by other MSM due to sexual orientation (adjusted odds ratio [aOR]: 1.3, 95% confidence interval [CI] 1.1-1.7, p < .01). MSM with high social cohesion had almost twice the odds of HIV testing in the last 12 months (aOR: 1.8, 95% CI 1.1-3.3, p < .05) as MSM with medium social cohesion, though the overall social cohesion variable was not found to be significant using a Wald test in either the adjusted or unadjusted logistic regression models. These data suggest that building solidarity and trust within and between groups may be a strategy to improve uptake of HIV testing.
Modelling increased soil cohesion by plant roots with EUROSEM
NASA Astrophysics Data System (ADS)
de Baets, S.; Poesen, J.; Torri, D.; Salvador, M. P.
2009-04-01
Soil cohesion is an important variable to model soil detachment by runoff (Morgan et al., 1998a). As soil particles are not loose, soil detachment by runoff will be limited by the cohesion of the soil material. It is generally recognized that plant roots contribute to the overall cohesion of the soil. Determination of this increased cohesion and soil roughness however is complicated and measurements of shear strength and soil reinforcement by plant roots are very time- and labour consuming. A model approach offers an alternative for the assessment of soil cohesion provided by plant roots However, few erosion models account for the effects of the below-ground biomass in their calculation of erosion rates. Therefore, the main objectives of this study is to develop an approach to improve an existing soil erosion model (EUROSEM) accounting for the erosion-reducing effects of roots. The approach for incorporating the root effects into this model is based on a comparison of measured soil detachment rates for bare and for root-permeated topsoil samples with predicted erosion rates under the same flow conditions using the erosion equation of EUROSEM. Through backwards calculation, transport capacity efficiencies and corresponding soil cohesion values can be assessed for bare and root-permeated topsoils respectively. The results are promising and show that grass roots provide a larger increase in soil cohesion as compared with tap-rooted species and that the increase in soil cohesion is not significantly different under wet and dry soil conditions, either for fibrous root systems or for tap root systems. Relationships are established between measured root density values and the corresponding calculated soil cohesion values, reflecting the effects of roots on the resistance of the topsoil to concentrated flow incision. These relationships enable one to incorporate the root effect into the soil erosion model EUROSEM, through adapting the soil cohesion input value. A scenario analysis performed with EUROSEM for different vegetation treatments, indicates that runoff and soil loss on root-permeated topsoils are slightly higher as compared to fully covered grass fields or harvested grass fields with some plant residue left, but much smaller as compared to bare topsoils. Moreover, when re-vegetating bare soils, roots are responsible for a large part of the reduction in soil loss and runoff by concentrated flow. Hence, this analysis shows that the contribution of roots to soil cohesion is very important for preventing soil loss and reducing runoff volume. The increase in soil shear strength due to the binding effect of roots on soil particles is two orders of magnitude lower as compared with soil reinforcement achieved when roots mobilize their tensile strength during soil shearing and root breakage.
Development and Application of a Cohesive Sediment Transport Model in Coastal Louisiana
NASA Astrophysics Data System (ADS)
Sorourian, S.; Nistor, I.
2017-12-01
The Louisiana coast has suffered from rapid land loss due to the combined effects of increasing the rate of eustatic sea level rise, insufficient riverine sediment input and subsidence. The sediment in this region is dominated by cohesive sediments (up to 80% of clay). This study presents a new model for calculating suspended sediment concentration (SSC) of cohesive sediments. Several new concepts are incorporated into the proposed model, which is capable of estimating the spatial and temporal variation in the concentration of cohesive sediment. First, the model incorporates the effect of electrochemical forces between cohesive sediment particles. Second, the wave friction factor is expressed in terms of the median particle size diameter in order to enhance the accuracy of the estimation of bed shear stress. Third, the erosion rate of cohesive sediments is also expressed in time-dependent form. Simulated SSC profiles are compared with field data collected from Vermilion Bay, Louisiana. The results of the proposed model agree well with the experimental data, as soon as steady state condition is achieved. The results of the new numerical models provide a better estimation of the suspended sediment concentration profile compared to the initial model developed by Mehta and Li, 2003. Among the proposed developments, the formulation of a time-dependent erosion rate shows the most accurate results. Coupling of present model with the Finite-Volume, primitive equation Community Ocean Model (FVCOM) would shed light on the fate of fine-grained sediments in order to increase overall retention and restoration of the Louisiana coastal plain.
Daniloski, Zharko; Smith, Susan
2017-10-15
Sister chromatids are held together by cohesin, a tripartite ring with a peripheral SA1/2 subunit, where SA1 is required for telomere cohesion and SA2 for centromere cohesion. The STAG2 gene encoding SA2 is often inactivated in human cancer, but not in in a manner associated with aneuploidy. Thus, how these tumors maintain chromosomal cohesion and how STAG2 loss contributes to tumorigenesis remain open questions. Here we show that, despite a loss in centromere cohesion, sister chromatids in STAG2 mutant tumor cells maintain cohesion in mitosis at chromosome arms and telomeres. Telomere maintenance in STAG2 mutant tumor cells occurred by either telomere recombination or telomerase activation mechanisms. Notably, these cells were refractory to telomerase inhibitors, indicating recombination can provide an alternative means of telomere maintenance. STAG2 silencing in normal human cells that lack telomerase led to increased recombination at telomeres, delayed telomere shortening, and postponed senescence onset. Insofar as telomere shortening and replicative senescence prevent genomic instability and cancer by limiting the number of cell divisions, our findings suggest that extending the lifespan of normal human cells due to inactivation of STAG2 could promote tumorigenesis by extending the period during which tumor-driving mutations occur. Cancer Res; 77(20); 5530-42. ©2017 AACR . ©2017 American Association for Cancer Research.
Quantum Mechanical Metric for Internal Cohesion in Cement Crystals
Dharmawardhana, C. C.; Misra, A.; Ching, Wai-Yim
2014-01-01
Calcium silicate hydrate (CSH) is the main binding phase of Portland cement, the single most important structural material in use worldwide. Due to the complex structure and chemistry of CSH at various length scales, the focus has progressively turned towards its atomic level comprehension. We study electronic structure and bonding of a large subset of the known CSH minerals. Our results reveal a wide range of contributions from each type of bonding, especially hydrogen bonding, which should enable critical analysis of spectroscopic measurements and construction of realistic C-S-H models. We find the total bond order density (TBOD) as the ideal overall metric for assessing crystal cohesion of these complex materials and should replace conventional measures such as Ca:Si ratio. A rarely known orthorhombic phase Suolunite is found to have higher cohesion (TBOD) in comparison to Jennite and Tobermorite, which are considered the backbone of hydrated Portland cement. PMID:25476741
Thermo-mechanical pressurization of experimental faults in cohesive rocks during seismic slip
NASA Astrophysics Data System (ADS)
Violay, M.; Di Toro, G.; Nielsen, S.; Spagnuolo, E.; Burg, J. P.
2015-11-01
Earthquakes occur because fault friction weakens with increasing slip and slip rates. Since the slipping zones of faults are often fluid-saturated, thermo-mechanical pressurization of pore fluids has been invoked as a mechanism responsible for frictional dynamic weakening, but experimental evidence is lacking. We performed friction experiments (normal stress 25 MPa, maximal slip-rate ∼3 ms-1) on cohesive basalt and marble under (1) room-humidity and (2) immersed in liquid water (drained and undrained) conditions. In both rock types and independently of the presence of fluids, up to 80% of frictional weakening was measured in the first 5 cm of slip. Modest pressurization-related weakening appears only at later stages of slip. Thermo-mechanical pressurization weakening of cohesive rocks can be negligible during earthquakes due to the triggering of more efficient fault lubrication mechanisms (flash heating, frictional melting, etc.).
NASA Astrophysics Data System (ADS)
Mahler, Michael; Gaganidze, Ermile; Aktaa, Jarir
2018-04-01
The experimental observation of anisotropic fracture behaviour of round blank polycrystalline tungsten was simulated using finite element (FE) method in combination with cohesive zone model. Experiments in the past had shown that due to the anisotropic microstructure the fracture toughness varies by factor of about two for different orientations. The reason is the crack propagation direction, which is - in some orientations - not the typical crack propagation direction for mode I fracture. In some directions the crack is not growing perpendicular to the crack opening tensile load. Nevertheless, in the present paper, the microstructure is modelled by FE mesh including cohesive zone elements which mimic grain boundaries (GB). This is based on the assumption that GB's are the weakest links in the structure. The use of the correct parameters to describe the fracture process allows the description of the observed experimental orientation dependent fracture toughness.
Elongational rheology and cohesive fracture of photo-oxidated LDPE
DOE Office of Scientific and Technical Information (OSTI.GOV)
Rolón-Garrido, Víctor H., E-mail: victor.h.rolongarrido@tu-berlin.de; Wagner, Manfred H.
2014-01-15
It was found recently that low-density polyethylene (LDPE) samples with different degrees of photo-oxidation represent an interesting system to study the transition from ductile to cohesive fracture and the aspects of the cohesive rupture in elongational flow. Sheets of LDPE were subjected to photo-oxidation in the presence of air using a xenon lamp to irradiate the samples for times between 1 day and 6 weeks. Characterisation methods included Fourier transform infrared spectroscopy, solvent extraction method, and rheology in shear and uniaxial extensional flows. Linear viscoelasticity was increasingly affected by increasing photo-oxidation due to crosslinking of LDPE, as corroborated by themore » carbonyl index, acid and aldehydes groups, and gel fraction. The molecular stress function model was used to quantify the experimental data, and the nonlinear model parameter β was found to be correlated with the gel content. The uniaxial data showed that the transition from ductile to cohesive fracture was shifted to lower elongational rates, the higher the gel content was. From 2 weeks photo-oxidation onwards, cohesive rupture occurred at every strain rate investigated. The true strain and true stress at cohesive fracture as well as the energy density applied to the sample up to fracture were analyzed. At low gel content, rupture was mainly determined by the melt fraction while at high gel content, rupture occurred predominantly in the gel structure. The strain at break was found to be independent of strain rate, contrary to the stress at break and the energy density. Thus, the true strain and not the stress at break or the energy density was found to be the relevant physical quantity to describe cohesive fracture behavior of photo-oxidated LDPE. The equilibrium modulus of the gel structures was correlated with the true strain at rupture. The stiffer the gel structure, the lower was the deformation tolerated before the sample breaks.« less
Investigation on the cohesive silt/clay-particle sediment via the coupled CFD-DEM simulations
NASA Astrophysics Data System (ADS)
Xu, S.; Sun, H.; Sun, R.
2017-12-01
Sedimentation of silt/clay particles happens ubiquitously in nature and engineering field. There have been abundant studies focusing on the settling velocity of the cohesive particles, while studies on the sediment deposited from silt/clay irregular particles, including the vertical concentration profile of sediment and the various forces among the deposited particles are still lacking. This paper aims to investigate the above topics by employing the CFD-DEM (Computational Fluid Dynamics-Discrete Element Method) simulations. In this work, we simulate the settling of the mono- and poly- dispersed silt/clay particles and mainly study the characteristics of the deposited cohesive sediment. We use the bonded particles to simulate the irregular silt/clay aggregates at the initial state and utilize the van der Waals force for all micro-particles to consider the cohesive force among silt/clay particles. The interparticle collision force and the fluid-particle interaction forces are also considered in our numerical model. The value of the mean structural density of cohesive sediment obtained from simulations is in good agreement with the previous research, and it is obviously smaller than no-cohesive sediment because of the existence of the silt/clay flocs. Moreover, the solid concentration of sediment increases with the growth of the depth. It is because the silt/clay flocs are more easily to break up due to the gradually increased submerged gravity of the deposited particles along the depth. We also obtain the noncontacted cohesive force and contact force profiles during the sedimentation and the self-weight consolidation process. The study of the concentration profile and the forces among silt/clay sediment will help to give an accurate initial condition for calculating the speed of the reconsolidation process by employing the artificial loads, which is necessary for practical designs of the land reclamation projects.
NASA Astrophysics Data System (ADS)
Lichtman, Ian; Thorne, Peter; Baas, Jacobus; O'Boyle, Louise; Cooke, Richard; Amoudry, Laurent; Bell, Paul; Aspden, Rebecca; Bass, Sarah; Davies, Alan; Hope, Julie; Malarkey, Jonathan; Manning, Andrew; Parsons, Daniel; Paterson, David; Peakall, Jeffrey; Schindler, Robert; Ye, Leiping
2014-05-01
There is a need to better understand the effects of cohesive and mixed sediments on coastal processes, to improve sediment transport models for the management of coastal erosion, siltation of navigation channels and habitat change. Although reasonable sediment transport predictors are available for pure sands, it still is not the case for mixed cohesive and non-cohesive sediments. Existing predictors mostly relate ripple dimensions to hydrodynamic conditions and median sediment grain diameter, assuming a narrow unimodal particle size distribution. Properties typical of mixed conditions, such as composition and cohesion for example, are not usually taken into account. This presents severe shortcomings to predictors' abilities. Indeed, laboratory experiments using mixed cohesive sediments have shown that bedform dimensions decrease with increasing bed mud content. In the field, one may expect current predictors to match data for well-sorted sands closely, but poorly for mixed sediments. Our work is part of the COHBED project and aims to: (1) examine, in field conditions, if ripple dimensions are significantly different for mixed cohesive sediment beds compared to beds with pure sand; (2) compare the field data with laboratory results that showed reduced ripple length due to cohesive mud content; and (3) assess the performance of a selection of ripple predictors for mixed sediment data. The COHBED project was set up to undertake laboratory experiments and fieldwork to study how physical and biological processes influence bedform development in a mixed cohesive-cohesionless sediment environment. As part of COHBED, a suite of instruments was deployed on tidal flats in the Dee Estuary (on the NW coast of England), collecting co-located measurements of the hydrodynamics, suspended sediment properties and bed morphology. The instruments occupied three sites collecting data over different bed compositions during a two week period (21 May to 4 June 2013). One site was located above a sandy bed, and the two others were above mixed beds of different mud content. The tide covered a full cycle from neaps to neaps and the weather provided onshore and offshore winds of varying strength. Bedform measurements were taken every half an hour using an Acoustic Ripple Profiler (ARP) that covered an area of about two square metres. Dynamic measurements of tides and waves were made using an Acoustic Doppler Velocimeter (ADV) at 8 Hz. Bed samples were taken when the tidal flats dried out at low tide and a sediment trap collected suspended load near the bed. In the presentation, comparisons of the sites will be made from measurements of the proportion of mud and biological sediment binders at each site and the ripple dimensions for different hydrodynamic conditions. Key words: bed morphology, current ripple, mixed sediment, cohesion, hydrodynamics, observations, tidal flat, estuary, Dee
Cohesive Strength of Gas-hydrate-bearing Marine Sediments
NASA Astrophysics Data System (ADS)
Cook, A. E.; Goldberg, D.
2005-12-01
We examine the relationship between gas hydrate saturation and the cohesive strength of marine sediments in a variety of continental margin settings. The cohesive strength (cohesion) is a fundamental physical property controlling sediment resistance to compressive failure. The cohesion (Co), is typically defined by the uncompressive rock strength and the friction angle, but it can also be related to the dynamic Young's modulus (ED), where: Co = 1.5*10-3 ED. The dynamic Young's modulus is computed using in situ Vp, Vs, and bulk density borehole logs. The Co profiles are compared to estimates of the in situ hydrate saturation, Sh, calculated using electrical resistivity logs and the modified Archie formula: Sh = 1 - (aRw/RΦm)1/n. We will present results of these comparisons from data collected during Ocean Drilling Program Legs at Cascadia margin (204 & 168) and Blake Ridge (164), the JIP gas hydrate drilling project in the Gulf of Mexico, and Malik permafrost wells. In general, at all the sites investigated, Co steadily increases downhole as sediments compact due to overburden. In marine sediments, cohesion ranges from 500-2000kPa above the BSR, with a baseline gradient usually between 5 and 10 kPa/m. Preliminary results show at Cascadia margin that sediments with Sh > 15%, Co increases dramatically, at least 200kPa greater than the general trend of the downhole gradient. This suggests that Co is affected directly by Sh, and may be related to the rate of change in Sh (e.g. gradual or sharp) as a function of depth. Further study on the relationship between Co and Sh may provide information on the growth habit of gas hydrates in sediment pore spaces.
Internal and surface waves in vibrofluidized granular materials: Role of cohesion
NASA Astrophysics Data System (ADS)
Huang, Kai
2018-05-01
Wave phenomena in vibrofluidized dry and partially wet granular materials confined in a quasi-two-dimensional geometry are investigated with numerical simulations considering individual particles as hard spheres. Short-ranged cohesive interactions arising from the formation of liquid bridges between adjacent particles are modeled by changing the velocity-dependent coefficient of restitution. Such a change effectively suppresses the formation of surface waves, in agreement with previous experimental observations. The difference in pattern creation arises from the suppressed momentum transfer due to wetting and it can be quantitatively understood from an analysis of binary impacts.
Developing Team Cohesion: A Quasi-Field Experiment
2004-03-01
social cohesion and task cohesion which may be very different and often produced opposite effects. Carless and Depaola (2000) defined task cohesion as... Social cohesion was defined as the motivation to develop and retain social interaction within the group. Whether cohesion is studied as one construct...that task cohesion and social cohesion have differing effects on performance. Mullen and Cooper (1994) showed that task cohesion had a positive
Hoss, Darby J.; Knepper, Robert; Hotchkiss, Peter J.; ...
2016-03-23
In this study, cohesive Hamaker constants of solid materials are measured via optical and dielectric properties (i.e., Lifshitz theory), inverse gas chromatography (IGC), and contact angle measurements. To date, however, a comparison across these measurement techniques for common energetic materials has not been reported. This has been due to the inability of the community to produce samples of energetic materials that are readily compatible with contact angle measurements. Here we overcome this limitation by using physical vapor deposition to produce thin films of five common energetic materials, and the contact angle measurement approach is applied to estimate the cohesive Hamakermore » constants and surface energy components of the materials. The cohesive Hamaker constants range from 85 zJ to 135 zJ across the different films. When these Hamaker constants are compared to prior work using Lifshitz theory and nonpolar probe IGC, the relative magnitudes can be ordered as follows: contact angle > Lifshitz > IGC. Furthermore, the dispersive surface energy components estimated here are in good agreement with those estimated by IGC. Due to these results, researchers and technologists will now have access to a comprehensive database of adhesion constants which describe the behavior of these energetic materials over a range of settings.« less
Compaction of Confining Materials in Pillar Blast Tests
NASA Astrophysics Data System (ADS)
Petropoulos, N.; Wimmer, M.; Johansson, D.; Nordlund, E.
2018-06-01
Two confined pillar tests were conducted at the Kiirunavaara mine to investigate the degree of compaction of three materials, i.e., 0-32-mm backfilled material, a blend of ore and waste material and caved material. Two blastholes were drilled parallel to each pillar wall, and several measurement holes were drilled in between the blastholes through each pillar. Both the measurement holes and backfilled materials, except the caved material, were instrumented. Two types of measurements were taken: dynamic measurements with accelerometers, and static measurements which considered the location of the instrumentation pre- and post-blast. Dynamic measurements involved the burden movement and the confining material behavior, and static measurements contained the final location of sensors inside and the angle of repose of the confining material. The results showed that the size distribution of the confining material affects its behavior under dynamic loading. The backfilled materials showed an apparent cohesion forming an agglomeration on the surface of the blasted burden. The burden moved as one slab due to simultaneous detonation. A gap was formed between the blasted burden and the new face. This gap was partially filled with burden erosion material which was finer fragmented than the blasted burden material.
Loss of tight junction barrier function and its role in cancer metastasis.
Martin, Tracey A; Jiang, Wen G
2009-04-01
As the most apical structure between epithelial and endothelial cells, tight junctions (TJ) are well known as functioning as a control for the paracellular diffusion of ions and certain molecules. It has however, become increasingly apparent that the TJ has a vital role in maintaining cell to cell integrity and that the loss of cohesion of the structure can lead to invasion and thus metastasis of cancer cells. This article will present data showing how modulation of expression of TJ molecules results in key changes in TJ barrier function leading to the successful metastasis of a number of different cancer types.
C-NAP1 and rootletin restrain DNA damage-induced centriole splitting and facilitate ciliogenesis.
Conroy, Pauline C; Saladino, Chiara; Dantas, Tiago J; Lalor, Pierce; Dockery, Peter; Morrison, Ciaran G
2012-10-15
Cilia are found on most human cells and exist as motile cilia or non-motile primary cilia. Primary cilia play sensory roles in transducing various extracellular signals, and defective ciliary functions are involved in a wide range of human diseases. Centrosomes are the principal microtubule-organizing centers of animal cells and contain two centrioles. We observed that DNA damage causes centriole splitting in non-transformed human cells, with isolated centrioles carrying the mother centriole markers CEP170 and ninein but not kizuna or cenexin. Loss of centriole cohesion through siRNA depletion of C-NAP1 or rootletin increased radiation-induced centriole splitting, with C-NAP1-depleted isolated centrioles losing mother markers. As the mother centriole forms the basal body in primary cilia, we tested whether centriole splitting affected ciliogenesis. While irradiated cells formed apparently normal primary cilia, most cilia arose from centriolar clusters, not from isolated centrioles. Furthermore, C-NAP1 or rootletin knockdown reduced primary cilium formation. Therefore, the centriole cohesion apparatus at the proximal end of centrioles may provide a target that can affect primary cilium formation as part of the DNA damage response.
Carrasco, Maria Augusta; Nguyen, Trang Q; Barrington, Clare; Perez, Martha; Donastorg, Yeycy; Kerrigan, Deanna
2018-07-01
Evidence indicates that social cohesion is a successful strategy to improve consistent condom use (CCU) among female sex workers. However, the individual and layered or combined effect that various types of overlapping stigmas may have on CCU between female sex workers living with HIV and their clients and steady partners has not been analyzed. Drawing on the Abriendo Puertas cohort of female sex workers living with HIV in the Dominican Republic, we used structural equation modeling to test the hypothesis that both HIV stigma and sex work stigma mediate the association between social cohesion and CCU and that they have a layered effect. The results indicated that HIV stigma mediated the association between social cohesion and CCU with clients and partners, while sex work-related stigma did not. There was no evidence of a layered HIV stigma and sex work stigma effect, which may be due to methodological limitations to handle highly correlated latent variables. Findings highlight the need to address internalized HIV stigma within the context of community-based approaches to enhance their HIV prevention impact. This will help to reduce the risk of HIV re-infection with a new distinct HIV viral strain, STI infection, and onward HIV transmission among female sex workers living with HIV.
Regolith grain size and cohesive strength of near-Earth Asteroid (29075) 1950 DA
NASA Astrophysics Data System (ADS)
Gundlach, B.; Blum, J.
2015-09-01
Due to its fast rotation period of 2.12 h, about half of the surface of near-Earth Asteroid (29075) 1950 DA experiences negative (i.e., outward directed) acceleration levels (Rozitis, B., Maclennan, E., Emery, J.P. [2014]. Nature 512, 174-176). Thus, cohesion of the surface material is mandatory to prevent rotational breakup of the asteroid. Rozitis et al. (Rozitis, B., Maclennan, E., Emery, J.P. [2014]. Nature 512, 174-176) concluded that a grain size of ∼6 cm or lower is needed to explain the required cohesive strength of 64-20+12Pa . Here, we present another approach to determine the grain size of near-Earth Asteroid (29075) 1950 DA by using the thermal inertia value from Rozitis et al. (Rozitis, B., Maclennan, E., Emery, J.P. [2014]. Nature 512, 174-176) and a model of the heat conductivity of the surface regolith (Gundlach, B., Blum, J. [2013]. Icarus 223, 479-492). This method yields a mean particle radius ranging from 32 μm to 117 μm. The derived grain sizes are then used to infer the cohesive strength of the surface material of Asteroid (29075) 1950 DA (ranging from 24 Pa to 88 Pa), by using laboratory measurements of the tensile strength of powders.
On Critical States, Rupture States and Interlocking Strength of Granular Materials.
Szalwinski, Chris M
2017-07-27
The Mohr-Coulomb theory of strength identifies cohesion and internal friction as the two principal contributions to the shear strength of a granular material. The contribution of cohesion in over-compacted granular materials has been challenged and replacing cohesion with interlocking has been proposed. A theory of rupture strength that includes interlocking is derived herein. The physics-chemistry concept of critical state is elaborated to accommodate granular materials, based on empirical definitions established in the fields of soil mechanics and bulk solids' flow. A surface in state space, called the critical compaction surface, separates over-compacted states from lightly compacted states. The intersection of this surface with the Mohr-Coulomb envelope forms the critical state surface for a granular material. The rupture strength of an over-compacted granular material is expressed as the sum of cohesion, internal friction and interlocking strength. Interlocking strength is the shear strength contribution due to over-compaction and vanishes at critical state. The theory allows migrations from one critical state to another. Changes in specific volume during such migrations are related to changes in mean-normal effective stress and uncoupled from changes in shearing strain. The theory is reviewed with respect to two established research programs and underlying assumptions are identified.
NASA Astrophysics Data System (ADS)
Okabe, Tomonaga; Yashiro, Shigeki
This study proposes the cohesive zone model (CZM) for predicting fatigue damage growth in notched carbon-fiber-reinforced composite plastic (CFRP) cross-ply laminates. In this model, damage growth in the fracture process of cohesive elements due to cyclic loading is represented by the conventional damage mechanics model. We preliminarily investigated whether this model can appropriately express fatigue damage growth for a circular crack embedded in isotropic solid material. This investigation demonstrated that this model could reproduce the results with the well-established fracture mechanics model plus the Paris' law by tuning adjustable parameters. We then numerically investigated the damage process in notched CFRP cross-ply laminates under tensile cyclic loading and compared the predicted damage patterns with those in experiments reported by Spearing et al. (Compos. Sci. Technol. 1992). The predicted damage patterns agreed with the experiment results, which exhibited the extension of multiple types of damage (e.g., splits, transverse cracks and delaminations) near the notches.
Investigating Some Technical Issues on Cohesive Zone Modeling of Fracture
NASA Technical Reports Server (NTRS)
Wang, John T.
2011-01-01
This study investigates some technical issues related to the use of cohesive zone models (CZMs) in modeling fracture processes. These issues include: why cohesive laws of different shapes can produce similar fracture predictions; under what conditions CZM predictions have a high degree of agreement with linear elastic fracture mechanics (LEFM) analysis results; when the shape of cohesive laws becomes important in the fracture predictions; and why the opening profile along the cohesive zone length needs to be accurately predicted. Two cohesive models were used in this study to address these technical issues. They are the linear softening cohesive model and the Dugdale perfectly plastic cohesive model. Each cohesive model constitutes five cohesive laws of different maximum tractions. All cohesive laws have the same cohesive work rate (CWR) which is defined by the area under the traction-separation curve. The effects of the maximum traction on the cohesive zone length and the critical remote applied stress are investigated for both models. For a CZM to predict a fracture load similar to that obtained by an LEFM analysis, the cohesive zone length needs to be much smaller than the crack length, which reflects the small scale yielding condition requirement for LEFM analysis to be valid. For large-scale cohesive zone cases, the predicted critical remote applied stresses depend on the shape of cohesive models used and can significantly deviate from LEFM results. Furthermore, this study also reveals the importance of accurately predicting the cohesive zone profile in determining the critical remote applied load.
It is Time to Rescind Don’t Ask, Don’t Tell
2009-04-02
cohesion and that in turn would affect accomplishing the mission. A study done at UC, Davis, makes a distinction between social cohesion and task...cohesion.22 Social cohesion is the nature and quality of emotional bonds of friendship, closeness, etc. and task cohesion is a shared commitment among...studies of cohesion and performance it is task cohesion, not social cohesion or group pride that drives group performance. Professor MacCoun also
Deng, Wen-Yi; Yuan, Min-Hao; Mei, Jing; Liu, Ya-Jun; Su, Ya-Xin
2017-03-01
Stickiness phenomenon is widely observed in sewage sludge drying practices. This paper is aimed at demonstrating and comparing the sticky properties of sewage sludge through non-agitated and agitated drying tests specially designed for sewage sludge. Special attentions were paid to the effects of additives, i.e. CaO, fine sawdust (FSD) and coarse sawdust (CSD), on the adhesive and cohesive characteristics of sewage sludge. The results indicated that the sticky properties of the sludge were markedly different under the different testing methods, and was also greatly influenced by CaO or sawdust addition. For instance, in the non-agitated drying tests, CaO can significantly enhance the maximum adhesive and cohesive stresses of the sludge, whereas in the agitated drying tests, the torque of agitation, which strongly correlated with the cohesive stress of the sludge, was lowered by CaO addition. During agitated drying process, sludge lump with CaO addition started to break up at higher moisture content than that of original sludge. On the other hand, sawdust also affected the sticky properties of sludge in a way that was totally different with CaO. After sawdust addition (at 5-10%WS (wet sludge basis)), the cohesive stress of the sludge was markedly increased due to strengthening of mechanical interlocking inside the sludge, whereas the adhesiveness of the sludge was lowered by sawdust addition. The influencing mechanisms of CaO and sawdust under the different testing methods were detailedly discussed in the paper. Copyright © 2016 Elsevier Ltd. All rights reserved.
Does a satisfactory relationship with her mother influence when a 16-year-old begins to have sex?
Kovar, Cheryl L; Salsberry, Pamela J
2012-01-01
To examine aspects of the mother-daughter relationship as perceived by the 16-year-old (cohesion, flexibility, communication, monitoring, and satisfaction with time spent together) as they relate to when the daughter began having sex. A secondary analysis using data from the National Longitudinal Survey of Youth Child (1992-2000) and Young Adult (1996-2004) surveys were analyzed (N = 1,592). Logistic regression models estimated reports of cohesion, flexibility, communication, monitoring, and satisfaction with time spent together with sexual initiation by age 16. All models controlled for the mother's sociodemographic characteristics, lack of independence due to sisters in the sample, and extended time away from mother. Girls who reported being satisfied with the amount of time spent with their mother were less likely to report early sexual initiation. In addition, these girls were three times more likely to report good communication and four times more likely to report high levels of cohesion with their mothers. Individually, in addition to satisfaction with time spent together, high levels of cohesion and good communication were also associated with lower reports of sexual initiation by age 16. The feeling of being satisfied with the time spent together appears to be a global measure of the individual dimensions of cohesion and communication. Efforts in delaying sexual initiation in adolescents need to be directed at the mother-daughter relationship. Interventions to develop these dimensions within the relationship during early adolescence, as compared to interventions when sexual activity may have already occurred, are warranted.
Interface structure and mechanics between graphene and metal substrates: a first-principles study
NASA Astrophysics Data System (ADS)
Xu, Zhiping; Buehler, Markus J.
2010-12-01
Graphene is a fascinating material not only for technological applications, but also as a test bed for fundamental insights into condensed matter physics due to its unique two-dimensional structure. One of the most intriguing issues is the understanding of the properties of graphene and various substrate materials. In particular, the interfaces between graphene and metal substrates are of critical importance in applications of graphene in integrated electronics, as thermal materials, and in electromechanical devices. Here we investigate the structure and mechanical interactions at a graphene-metal interface through density functional theory (DFT)-based calculations. We focus on copper (111) and nickel (111) surfaces adhered to a monolayer of graphene, and find that their cohesive energy, strength and electronic structure correlate directly with their atomic geometry. Due to the strong coupling between open d-orbitals, the nickel-graphene interface has a much stronger cohesive energy with graphene than copper. We also find that the interface cohesive energy profile features a well-and-shoulder shape that cannot be captured by simple pair-wise models such as the Lennard-Jones potential. Our results provide a detailed understanding of the interfacial properties of graphene-metal systems, and help to predict the performance of graphene-based nanoelectronics and nanocomposites. The availability of structural and energetic data of graphene-metal interfaces could also be useful for the development of empirical force fields for molecular dynamics simulations.
Sanford, L.P.; Halka, J.P.
1993-01-01
A paradigm of cohesive sediment transport research is that erosion and deposition are mutually exclusive. Many laboratory studies have shown that there is a velocity/stress threshold below which erosion does not occur and a lower threshold above which deposition does not occur. In contrast, a deposition threshold is not included in standard noncohesive sediment transport models, allowing erosion and deposition to occur simultaneously. Several researchers have also modeled erosion and deposition of mud without a deposition threshold. This distinction can have important implications for suspended sediment transport predictions and for data interpretation. Model-data comparisons based on observations of in situ erosion and deposition of upper Chesapeake Bay mud indicate poor agreement when the sediments are modeled as a single resuspended particle class and mutually exclusive erosion and deposition is assumed. The total resuspended sediment load increases in conjunction with increasing bottom shear stress as anticipated, but deposition is initiated soon after the shear stress begins to decrease and long before the stress falls below the value at which erosion had previously begun. Models assuming no critical stress for deposition, with continuous deposition proportional to the near bottom resuspended sediment concentration, describe the data better. Empirical parameter values estimated from these model fits are similar to other published values for estuarine cohesive sediments, indicating significantly greater erodability for higher water content surface sediments and settling velocities appropriate for large estuarine flocs. The apparent failure of the cohesive paradigm when applied to in situ data does not mean that the concept of a critical stress for deposition is wrong. Two possibilities for explaining the observed discrepancies are that certain aspects of in situ conditions have not been replicated in the laboratory experiments underlying the cohesive paradigm, and that in situ sediment behavior is better described as a sequence of particle classes than as the single particle class modeled here. However, the in situ measurements needed to resolve these questions are very difficult and data generally are not available. For practical modeling purposes, allowing continuous deposition of a single resuspended particle class may often give quite satisfactory results. ?? 1993.
An EMAT-based shear horizontal (SH) wave technique for adhesive bond inspection
NASA Astrophysics Data System (ADS)
Arun, K.; Dhayalan, R.; Balasubramaniam, Krishnan; Maxfield, Bruce; Peres, Patrick; Barnoncel, David
2012-05-01
The evaluation of adhesively bonded structures has been a challenge over the several decades that these structures have been used. Applications within the aerospace industry often call for particularly high performance adhesive bonds. Several techniques have been proposed for the detection of disbonds and cohesive weakness but a reliable NDE method for detecting interfacial weakness (also sometimes called a kissing bond) has been elusive. Different techniques, including ultrasonic, thermal imaging and shearographic methods, have been proposed; all have had some degree of success. In particular, ultrasonic methods, including those based upon shear and guided waves, have been explored for the assessment of interfacial bond quality. Since 3-D guided shear horizontal (SH) waves in plates have predominantly shear displacement at the plate surfaces, we conjectured that SH guided waves should be influenced by interfacial conditions when they propagate between adhesively bonded plates of comparable thickness. This paper describes a new technique based on SH guided waves that propagate within and through a lap joint. Through mechanisms we have yet to fully understand, the propagation of an SH wave through a lap joint gives rise to a reverberation signal that is due to one or more reflections of an SH guided wave mode within that lap joint. Based upon a combination of numerical simulations and measurements, this method shows promise for detecting and classifying interfacial bonds. It is also apparent from our measurements that the SH wave modes can discriminate between adhesive and cohesive bond weakness in both Aluminum-Epoxy-Aluminum and Composite-Epoxy-Composite lap joints. All measurements reported here used periodic permanent magnet (PPM) Electro-Magnetic Acoustic Transducers (EMATs) to generate either or both of the two lowest order SH modes in the plates that comprise the lap joint. This exact configuration has been simulated using finite element (FE) models to describe the SH mode generation, propagation and reception. Of particular interest is that one SH guided wave mode (probably SH0) reverberates within the lap joint. Moreover, in both simulations and measurements, features of this so-called reverberation signal appear to be related to interfacial weakness between the plate (substrate) and the epoxy bond. The results of a hybrid numerical (FE) approach based on using COMSOL to calculate the driving forces within an elastic solid and ABAQUS to propagate the resulting elastic disturbances (waves) within the plates and lap joint are compared with measurements of SH wave generation and reception in lap joint specimens having different interfacial and cohesive bonding conditions.
Implications of Integrating Women into the Marine Corps Infantry
2015-12-01
findings and implications from our study. Research on Cohesion In general, prior research demonstrates that more cohesive groups perform better than less...woman in the group ,1 but the optimal proportion of women for group cohesion is not clear from the existing research . Finally, there are cohesion...that integration might have on group cohesion. This is for good reason: research on group cohesion has demonstrated that cohesion has a direct rela
Key Skills for Science Learning: The Importance of Text Cohesion and Reading Ability
ERIC Educational Resources Information Center
Hall, Sophie Susannah; Maltby, John; Filik, Ruth; Paterson, Kevin B.
2016-01-01
To explore the importance of text cohesion, we conducted two experiments. We measured online (reading times) and offline (comprehension accuracy) processes for texts that were high and low cohesion. In study one (n?=?60), we manipulated referential cohesion using noun repetition (high cohesion) and synonymy (low cohesion). Students showed enhanced…
Social Cohesion as the Goal: Can Social Cohesion Be Directly Pursued?
ERIC Educational Resources Information Center
Koonce, Kelly A.
2011-01-01
This article establishes an understanding of social cohesion in general and discusses organizations and activities that are known to promote social cohesion before introducing organizations that claim to work toward social cohesion as one of their main priorities. The Council of Europe's Directorate General of Social Cohesion represents a…
Effect of irradiated pork on physicochemical properties of meat emulsions
NASA Astrophysics Data System (ADS)
Choi, Yun-Sang; Sung, Jung-Min; Jeong, Tae-Jun; Hwang, Ko-Eun; Song, Dong-Heon; Ham, Youn-Kyung; Kim, Hyun-Wook; Kim, Young-Boong; Kim, Cheon-Jei
2016-02-01
The effect of pork irradiated with doses up to 10 kGy on meat emulsions formulated with carboxy methyl cellulose (CMC) was investigated. Raw pork was vacuums packaged at a thickness of 2.0 cm and irradiated by X-ray linear accelerator (15 kW, 5 MeV). The emulsion had higher lightness, myofibrillar protein solubility, total protein solubility, and apparent viscosity with increasing doses, whereas cooking loss, total expressible fluid separation, and hardness decreased. There were no significant differences in fat separation, sarcoplasmic protein solubility, springiness, and cohesiveness. Our results indicated that it is treatment by ionizing radiation which causes the effects the physicochemical properties of the final raw meat product.
NASA Technical Reports Server (NTRS)
Naghipour, P.; Pineda, E. J.; Arnold, S.
2014-01-01
Lightning is a major cause of damage in laminated composite aerospace structures during flight. Due to the dielectric nature of Carbon fiber reinforced polymers (CFRPs), the high energy induced by lightning strike transforms into extreme, localized surface temperature accompanied with a high-pressure shockwave resulting in extensive damage. It is crucial to develop a numerical tool capable of predicting the damage induced from a lightning strike to supplement extremely expensive lightning experiments. Delamination is one of the most significant failure modes resulting from a lightning strike. It can be extended well beyond the visible damage zone, and requires sophisticated techniques and equipment to detect. A popular technique used to model delamination is the cohesive zone approach. Since the loading induced from a lightning strike event is assumed to consist of extreme localized heating, the cohesive zone formulation should additionally account for temperature effects. However, the sensitivity to this dependency remains unknown. Therefore, the major focus point of this work is to investigate the importance of this dependency via defining various temperature dependency profiles for the cohesive zone properties, and analyzing the corresponding delamination area. Thus, a detailed numerical model consisting of multidirectional composite plies with temperature-dependent cohesive elements in between is subjected to lightning (excessive amount of heat and pressure) and delamination/damage expansion is studied under specified conditions.
Molecular interactions of mussel protective coating protein, mcfp-1, from Mytilus californianus.
Lu, Qingye; Hwang, Dong Soo; Liu, Yang; Zeng, Hongbo
2012-02-01
Protective coating of the byssus of mussels (Mytilus sp.) has been suggested as a new paradigm of medical coating due to its high extensibility and hardness co-existence without their mutual detriment. The only known biomacromolecule in the extensible and tough coating on the byssus is mussel foot protein-1 (mfp-1), which is made up with positively charged residues (~20 mol%) and lack of negatively charged residues. Here, adhesion and molecular interaction mechanisms of Mytilus californianus foot protein-1 (mcfp-1) from California blue mussel were investigated using a surface forces apparatus (SFA) in buffer solutions of different ionic concentrations (0.2-0.7 M) and pHs (3.0-5.5). Strong and reversible cohesion between opposed positively charged mcfp-1 films was measured in 0.1 M sodium acetate buffer with 0.1 M KNO(3). Cohesion of mcfp-1 was gradually reduced with increasing the ionic strength, but was not changed with pH variations. Oxidation of 3,4-dihydroxyphenylalanine (DOPA) residues of mcfp-1, a key residue for adhesive and coating proteins of mussel, didn't change the cohesion strength of mcfp-1 films, but the addition of chemicals with aromatic groups (i.e., aspirin and 4-methylcatechol) increased the cohesion. These results suggest that the cohesion of mcfp-1 films is mainly mediated by cation-π interactions between the positively charged residues and benzene rings of DOPA and other aromatic amino acids (~20 mol% of total amino acids of mcfp-1), and π-π interactions between the phenyl groups in mcfp-1. The adhesion mechanism obtained for the mcfp-1 proteins provides important insight into the design and development of functional biomaterials and coatings mimicking the extensible and robust mussel cuticle coating. Copyright © 2011 Elsevier Ltd. All rights reserved.
A simple shear limited, single size, time dependent flocculation model
NASA Astrophysics Data System (ADS)
Kuprenas, R.; Tran, D. A.; Strom, K.
2017-12-01
This research focuses on the modeling of flocculation of cohesive sediment due to turbulent shear, specifically, investigating the dependency of flocculation on the concentration of cohesive sediment. Flocculation is important in larger sediment transport models as cohesive particles can create aggregates which are orders of magnitude larger than their unflocculated state. As the settling velocity of each particle is determined by the sediment size, density, and shape, accounting for this aggregation is important in determining where the sediment is deposited. This study provides a new formulation for flocculation of cohesive sediment by modifying the Winterwerp (1998) flocculation model (W98) so that it limits floc size to that of the Kolmogorov micro length scale. The W98 model is a simple approach that calculates the average floc size as a function of time. Because of its simplicity, the W98 model is ideal for implementing into larger sediment transport models; however, the model tends to over predict the dependency of the floc size on concentration. It was found that the modification of the coefficients within the original model did not allow for the model to capture the dependency on concentration. Therefore, a new term within the breakup kernel of the W98 formulation was added. The new formulation results is a single size, shear limited, and time dependent flocculation model that is able to effectively capture the dependency of the equilibrium size of flocs on both suspended sediment concentration and the time to equilibrium. The overall behavior of the new model is explored and showed align well with other studies on flocculation. Winterwerp, J. C. (1998). A simple model for turbulence induced flocculation of cohesive sediment. .Journal of Hydraulic Research, 36(3):309-326.
NASA Astrophysics Data System (ADS)
Yu, Xinting; Hörst, Sarah M.; He, Chao; McGuiggan, Patricia; Bridges, Nathan T.
2017-12-01
To understand the origin of the dunes on Titan, it is important to investigate the material properties of Titan's organic sand particles on Titan. The organic sand may behave distinctively compared to the quartz/basaltic sand on terrestrial planets (Earth, Venus, and Mars) due to differences in interparticle forces. We measured the surface energy (through contact angle measurements) and elastic modulus (through Atomic Force Microscopy) of the Titan aerosol analog (tholin). We find that the surface energy of a tholin thin film is about 70.9 mN/m, and its elastic modulus is about 3.0 GPa (similar to hard polymers like PMMA and polystyrene). For two 20 μm diameter particles, the theoretical cohesion force is therefore 3.3 μN. We directly measured interparticle forces for relevant materials: tholin particles are 0.8 ± 0.6 μN, while the interparticle cohesion between walnut shell particles (a typical model materials for the Titan Wind Tunnel, TWT) is only 0.4 ± 0.1 μN. The interparticle cohesion forces are much larger for tholins and presumably Titan sand particles than materials used in the TWT. This suggests that we should increase the interparticle force in both analog experiments (TWT) and threshold models to correctly translate the results to real Titan conditions. The strong cohesion of tholins may also inform us how the small aerosol particles (˜1 μm) in Titan's atmosphere are transformed into large sand particles (˜200 μm). It may also support the cohesive sand formation mechanism suggested by Rubin and Hesp (2009), where only unidirectional wind is needed to form linear dunes on Titan.
Flocculation Settling Dynamics of Natural Cohesive Suspended Sediments: "Floccin' Across the USA!"
NASA Astrophysics Data System (ADS)
Manning, A. J.; Schoellhamer, D. H.; Mehta, A. J.; Schladow, G.; Monismith, S. G.; Huang, I. B.; Kuwabara, J. S.; Carter, J. L.; Sheremet, A.; Parsons, D. R.; Whitehouse, R. J. S.; Todd, D.; Benson, T.; Spearman, J.
2017-12-01
Many coastal and inland waterways are dominated by muddy sediments; comprising a mixture of clay minerals and various types of organic matter. When cohesive sediment is entrained into suspension, the particles tend to flocculate. Flocs are less dense, but faster settling than their constituent particles thus affecting their depositional characteristics. As flocs grow, their effective densities generally decrease, but their settling rates rise due to the Stokes' Law relationship. Flocculation effects become even more complex when purely cohesive sediments are mixed with different ratios of non-cohesive sediments, and if biological activity (e.g., exudate production) affects the resultant cohesion. Developing instrumentation that can provide key physical and dynamical data on depositional rates of flocculating sediments is extremely important in advancing our understanding of natural flocculation processes. Complementary qualitative and quantitative data improve our understanding of the depositional and aggregational physical processes through parameterization. This presentation will demonstrate recent advances in the study of the flocculation process through the use of video image technology. One such device pioneered at HR Wallingford, and implemented with co-authors, is the high-resolution floc video camera, LabSFLOC - Laboratory Spectral Flocculation Characteristics (developed by Prof. Manning). LabSFLOC can observe (directly or indirectly) floc spectral physical properties, including: floc size, settling velocity, effective density, porosity, shape, mass, and settling flux (using controlled volume referencing). These data are highly desirable for sediment transport modelers. Examples of floc measurements from locations in estuaries, tidal lagoons, river deltas, and lakes from locations across the US will be presented. In addition, we will demonstrate how video floc data can be used to parameterize floc settling characteristics for use in modeling.
NASA Astrophysics Data System (ADS)
Noack, Markus; Gerbersdorf, Sabine; Hillebrand, Gudrun; Kasimir, Petra; Wieprecht, Silke
2014-05-01
Deposition of contaminated sediments in areas of no or low flow velocity such as groyne fields or impounded river stretches represent a significant thread to water quality if long-deposited sediments are remobilized during flood and storm events. In contrast to non-cohesive sediments the dynamics of cohesive sediments is not fully understood mainly because of multiple physico-chemical factors and variable biological influence. Hence, site-specific investigations are required to develop water management strategies as well as modelling approaches to predict the dynamic behavior of cohesive material. The Institute for Modelling Hydraulic and Environmental Systems (IWS, University of Stuttgart) has a strong experience in developing measuring strategies and techniques to deal with the complex interactions between biological and sedimentary characteristics regarding erosion and remobilization of cohesive material. Specifically, the detection of critical shear stresses for incipient motion of cohesive particles has been realized for both one laboratory device (SETEG) and an in-situ device. For site-specific investigations ideally both methods should be combined. The first method (SETEG) includes the on-site extraction of sediment cores allowing for depth-dependent analysis under controlled laboratory conditions, while the second one measures the surface only but reduces possible artifacts due to sediment withdrawal and transport. Both methods were applied at groyne fields and deposition areas of the River Elbe and River Saale, which are both heavily affected by pollution of anthropogenic contaminants mainly originating from the release of chemical industry before 1990. Next to the detection of critical shear stresses and erosion rates, further sedimentary attributes are analyzed such as particle size distribution, water content and density as well as biological attributes such as TOC and microbial mass. The analyses of the sediment cores result in vertical profiles for all sedimentary and biological parameters giving highly complementary insights into the rather complex erosion and resuspension properties of cohesive fine sediments. Further, the detected critical shear stress between the in-situ and laboratory device are compared and especially in case of deviations the biological parameters can be highly beneficial to explain the measured critical shear stress and variances between in situ and laboratory devices. The investigations in both study sites have shown that the joint application of the measuring devices gives comprehensive information which is required to determine the risk of remobilization properly. Keywords: cohesive sediments, critical shear stress, contaminated sediments, incipient motion, biostabilization
Wave-current induced erosion of cohesive riverbanks in northern Manitoba, Canada
NASA Astrophysics Data System (ADS)
Kimiaghalam, N.; Clark, S.; Ahmari, H.; Hunt, J.
2015-03-01
The field of cohesive soil erosion is still not fully understood, in large part due to the many soil parameters that affect cohesive soil erodibility. This study is focused on two channels, 2-Mile and 8-Mile channels in northern Manitoba, Canada, that were built to connect Lake Winnipeg with Playgreen Lake and Playgreen Lake with Kiskikittogisu Lake, respectively. The banks of the channels consist of clay rich soils and alluvial deposits of layered clay, silts and sands. The study of erosion at the sites is further complicated because the flow-induced erosion is combined with the effects of significant wave action due to the large fetch length on the adjacent lakes, particularly Lake Winnipeg that is the seventh largest lake in North America. The study included three main components: field measurements, laboratory experiments and numerical modelling. Field measurements consisted of soil sampling from the banks and bed of the channels, current measurements and water sampling. Grab soil samples were used to measure the essential physical and electrochemical properties of the riverbanks, and standard ASTM Shelby tube samples were used to estimate the critical shear stress and erodibility of the soil samples using an erosion measurement device (EMD). Water samples were taken to estimate the sediment concentration profile and also to monitor changes in sediment concentration along the channels over time. An Acoustic Doppler Current Profiler (ADCP) was used to collect bathymetry and current data, and two water level gauges have been installed to record water levels at the entrance and outlet of the channels. The MIKE 21 NSW model was used to simulate waves using historical winds and measured bathymetry of the channels and lakes. Finally, results from the wave numerical model, laboratory tests and current measurement were used to estimate the effect of each component on erodibility of the cohesive banks.
Strain engineering of the elasticity and the Raman shift of nanostructured TiO2
NASA Astrophysics Data System (ADS)
Liu, X. J.; Pan, L. K.; Sun, Z.; Chen, Y. M.; Yang, X. X.; Yang, L. W.; Zhou, Z. F.; Sun, Chang Q.
2011-08-01
Correlation between the elastic modulus (B) and the Raman shift (Δω) of TiO2 and their responses to the variation of crystal size, applied pressure, and measuring temperature have been established as a function depending on the order, length, and energy of a representative bond for the entire specimen. In addition to the derived fundamental information of the atomic cohesive energy, binding energy density, Debye temperature and nonlinear compressibility, theoretical reproduction of the observations clarified that (i) the size effect arises from the under-coordination induced cohesive energy loss and the energy density gain in the surface up to skin depth; (ii) the thermally softened B and Δω results from bond expansion and bond weakening due to vibration; and, (iii) the mechanically stiffened B and Δω results from bond compression and bond strengthening due to mechanical work hardening. With the developed premise, one can predict the changing trends of the concerned properties with derivatives of quantitative information as such from any single measurement alone.
Swat, Maciej H; Thomas, Gilberto L; Shirinifard, Abbas; Clendenon, Sherry G; Glazier, James A
2015-01-01
Tumor cells and structure both evolve due to heritable variation of cell behaviors and selection over periods of weeks to years (somatic evolution). Micro-environmental factors exert selection pressures on tumor-cell behaviors, which influence both the rate and direction of evolution of specific behaviors, especially the development of tumor-cell aggression and resistance to chemotherapies. In this paper, we present, step-by-step, the development of a multi-cell, virtual-tissue model of tumor somatic evolution, simulated using the open-source CompuCell3D modeling environment. Our model includes essential cell behaviors, microenvironmental components and their interactions. Our model provides a platform for exploring selection pressures leading to the evolution of tumor-cell aggression, showing that emergent stratification into regions with different cell survival rates drives the evolution of less cohesive cells with lower levels of cadherins and higher levels of integrins. Such reduced cohesivity is a key hallmark in the progression of many types of solid tumors.
Remeseiro, Silvia; Cuadrado, Ana; Carretero, María; Martínez, Paula; Drosopoulos, William C; Cañamero, Marta; Schildkraut, Carl L; Blasco, María A; Losada, Ana
2012-01-01
Cohesin is a protein complex originally identified for its role in sister chromatid cohesion, although increasing evidence portrays it also as a major organizer of interphase chromatin. Vertebrate cohesin consists of Smc1, Smc3, Rad21/Scc1 and either stromal antigen 1 (SA1) or SA2. To explore the functional specificity of these two versions of cohesin and their relevance for embryonic development and cancer, we generated a mouse model deficient for SA1. Complete ablation of SA1 results in embryonic lethality, while heterozygous animals have shorter lifespan and earlier onset of tumourigenesis. SA1-null mouse embryonic fibroblasts show decreased proliferation and increased aneuploidy as a result of chromosome segregation defects. These defects are not caused by impaired centromeric cohesion, which depends on cohesin-SA2. Instead, they arise from defective telomere replication, which requires cohesion mediated specifically by cohesin-SA1. We propose a novel mechanism for aneuploidy generation that involves impaired telomere replication upon loss of cohesin-SA1, with clear implications in tumourigenesis. PMID:22415365
Swat, Maciej H.; Thomas, Gilberto L.; Shirinifard, Abbas; Clendenon, Sherry G.; Glazier, James A.
2015-01-01
Tumor cells and structure both evolve due to heritable variation of cell behaviors and selection over periods of weeks to years (somatic evolution). Micro-environmental factors exert selection pressures on tumor-cell behaviors, which influence both the rate and direction of evolution of specific behaviors, especially the development of tumor-cell aggression and resistance to chemotherapies. In this paper, we present, step-by-step, the development of a multi-cell, virtual-tissue model of tumor somatic evolution, simulated using the open-source CompuCell3D modeling environment. Our model includes essential cell behaviors, microenvironmental components and their interactions. Our model provides a platform for exploring selection pressures leading to the evolution of tumor-cell aggression, showing that emergent stratification into regions with different cell survival rates drives the evolution of less cohesive cells with lower levels of cadherins and higher levels of integrins. Such reduced cohesivity is a key hallmark in the progression of many types of solid tumors. PMID:26083246
Nanostructured Composites: Effective Mechanical Property Determination of Nanotube Bundles
NASA Technical Reports Server (NTRS)
Saether, E.; Pipes, R. B.; Frankland, S. J. V.
2002-01-01
Carbon nanotubes naturally tend to form crystals in the form of hexagonally packed bundles or ropes that should exhibit a transversely isotropic constitutive behavior. Although the intratube axial stiffness is on the order of 1 TPa due to a strong network of delocalized bonds, the intertube cohesive strength is orders of magnitude less controlled by weak, nonbonding van der Waals interactions. An accurate determination of the effective mechanical properties of nanotube bundles is important to assess potential structural applications such as reinforcement in future composite material systems. A direct method for calculating effective material constants is developed in the present study. The Lennard-Jones potential is used to model the nonbonding cohesive forces. A complete set of transverse moduli are obtained and compared with existing data.
NASA Astrophysics Data System (ADS)
Abdelmalak, M. M.; Bulois, C.; Mourgues, R.; Galland, O.; Legland, J.-B.; Gruber, C.
2016-08-01
Cohesion and friction coefficient are fundamental parameters for scaling brittle deformation in laboratory models of geological processes. However, they are commonly not experimental variable, whereas (1) rocks range from cohesion-less to strongly cohesive and from low friction to high friction and (2) strata exhibit substantial cohesion and friction contrasts. This brittle paradox implies that the effects of brittle properties on processes involving brittle deformation cannot be tested in laboratory models. Solving this paradox requires the use of dry granular materials of tunable and controllable brittle properties. In this paper, we describe dry mixtures of fine-grained cohesive, high friction silica powder (SP) and low-cohesion, low friction glass microspheres (GM) that fulfill this requirement. We systematically estimated the cohesions and friction coefficients of mixtures of variable proportions using two independent methods: (1) a classic Hubbert-type shear box to determine the extrapolated cohesion (C) and friction coefficient (μ), and (2) direct measurements of the tensile strength (T0) and the height (H) of open fractures to calculate the true cohesion (C0). The measured values of cohesion increase from 100 Pa for pure GM to 600 Pa for pure SP, with a sub-linear trend of the cohesion with the mixture GM content. The two independent cohesion measurement methods, from shear tests and tension/extensional tests, yield very similar results of extrapolated cohesion (C) and show that both are robust and can be used independently. The measured values of friction coefficients increase from 0.5 for pure GM to 1.05 for pure SP. The use of these granular material mixtures now allows testing (1) the effects of cohesion and friction coefficient in homogeneous laboratory models and (2) testing the effect of brittle layering on brittle deformation, as demonstrated by preliminary experiments. Therefore, the brittle properties become, at last, experimental variables.
Measuring team cohesion: observations from the science.
Salas, Eduardo; Grossman, Rebecca; Hughes, Ashley M; Coultas, Chris W
2015-05-01
The aim of this study was to review literature relevant to cohesion measurement, explore developing measurement approaches, and provide theoretical and practical recommendations for optimizing cohesion measurement. Cohesion is essential for team effectiveness and performance, leading researchers to focus attention on understanding how to enhance it. However, cohesion is inconsistently defined and measured, making it difficult to compare findings across studies and limiting the ability to advance science and practice. We reviewed empirical research through which we uncovered specific information about cohesion's conceptualization, measurement, and relationships with performance, culminating in a set of current trends from which we provide suggestions and possible solutions to guide future efforts and help the field converge toward greater consistency. Cohesion demonstrates more significant relationships with performance when conceptualized using social and task (but not other) dimensions and when analyses are performed at the team level. Cohesion is inherently temporal, yet researchers rarely measure cohesion at multiple points during the life of a team. Finally, cohesion matters in large, dynamic collectives, complicating measurement. However, innovative and unobtrusive methodologies are being used, which we highlight. Practitioners and researchers are encouraged to define cohesion with task and social subdimensions and to measure with behavioral and attitudinal operationalizations. Individual and team-oriented items are recommended, though team-level analyses are most effective. Innovative/unobtrusive methods should be further researched to enable cohesion measurement longitudinally and in large, dynamic collectives. By applying our findings and conclusions, researchers and practitioners will be more likely to find consistent, reliable, and significant cohesion-to-performance relationships. This work is not subject to U.S. copyright restrictions.
NASA Astrophysics Data System (ADS)
Qian, Ye
Characterization of structural rebuilding and shear migration in cementitious materials in consideration of thixotropy Ye Qian From initial contact with water until hardening, and deterioration, cement and concrete materials are subjected to various chemical and physical transformations and environmental impacts. This thesis focuses on the properties during the fresh state, shortly after mixing until the induction period. During this period flow history, including shearing and resting, and hydration both play big roles in determining the rheological properties. The rheological properties of cement and concrete not only affect the casting and pumping process, but also very critical for harden properties and durability properties. Compared with conventional concrete, self-consolidating concrete (SCC) can introduce many advantages in construction application. These include readiness to apply, decreasing labor necessary for casting, and enhancing hardened properties. However, challenges still remain, such as issues relating to formwork pressure and multi-layer casting. Each of these issues is closely related to the property of thixotropy. From the microstructural point of view, thixotropy is described as structural buildup (flocculation) under rest and breakdown (deflocculation) under flow. For SCC, as well as other concrete systems, it is about balancing sufficient flowability during casting and rate of structural buildup after placement for the application at hand. For instance, relating to the issue of SCC formwork, it is ideal for the material to be highly flowable to achieve rapid casting, but then exhibit high rate of structural buildup to reduce formwork pressure. This can reduce the cost of formwork and reduce the risk of formwork failure. It is apparent that accurately quantifying the two aspects of thixotropy, i.e. structuration and destructuration, is key to tackling these challenges in field application. Thus, the overall objective of my doctoral study is to improve quantification of key parameters tied to thixotropy that we have identified to be important: static yield stress, cohesion and degree of shear-induced particle migration. The two main contributions are as follows: Firstly, I quantified structuration of fresh paste and mortar systems by measuring static yield stress. After an extensive review of various rheological methods to probe viscoelastic properties of yield stress fluids, I selected, developed, and implemented a creep recovery protocol. Creep results were supplemented by low-amplitude oscillatory shear results, and supported that the measured static yield stress corresponds to the solid-liquid transition. This improved quantification of static yield stress can help better understand the effect of mix composition on SCC formwork pressure development, as well as static segregation and stability. Since the static yield stress is measured before the structure is broken down, the effects of sand migration are eliminated. This study also analyzed effects of other supplementary cementitous materials such as nanoclay and fly ash. Results showed that nanoclay effectively increases static yield stress and structuration rate, while fly ash decreases static yield stress. To complement this investigation, I studied cohesion using the probe tack test, as cohesion is widely cited to be closely related to formwork pressure. I verified that probe tack test is a quick and useful method to measure static cohesion. Results showed that nanoclay increased cohesion dramatically while fly ash did not have an apparent effect on cohesion. Secondly, I developed an empirical model to fit the stress decay process under constant shear rate, For mortar systems, the stress decay can be attributed to two mechanisms: colloidal destructuration and sand migration. Such a model could be used to characterize particle migration and dynamic segregation, a critical issue for casting applications. In addition, shear induced particle migration is a widely recognized challenge in characterizing mortars and concretes through shear rheological methods. Therefore this model can help determine the range of shear rates within which migration can be minimized to guide the design of protocols for dynamic rheological characterization and to ultimately develop design strategies to minimize mitigation. Compared with currently existing methods, this model provides a faster approach to quantify the sand migration process, including kinetics.
Loughead, Todd M; Fransen, Katrien; Van Puyenbroeck, Stef; Hoffmann, Matt D; De Cuyper, Bert; Vanbeselaere, Norbert; Boen, Filip
2016-11-01
Two studies investigated the structure of different athlete leadership networks and its relationship to cohesion using social network analysis. In Study 1, we examined the relationship between a general leadership quality network and task and social cohesion as measured by the Group Environment Questionnaire (GEQ). In Study 2, we investigated the leadership networks for four different athlete leadership roles (task, motivational, social and external) and their association with task and social cohesion networks. In Study 1, the results demonstrated that the general leadership quality network was positively related to task and social cohesion. The results from Study 2 indicated positive correlations between the four leadership networks and task and social cohesion networks. Further, the motivational leadership network emerged as the strongest predictor of the task cohesion network, while the social leadership network was the strongest predictor of the social cohesion network. The results complement a growing body of research indicating that athlete leadership has a positive association with cohesion.
Liu, Chiung-Ju; Rawl, Susan M
2012-01-01
Increasing readability of written cancer prevention information is a fundamental step to increasing awareness and knowledge of cancer screening. Instead of readability formulas, the present study focused on text cohesion, which is the degree to which the text content ties together. The purpose of this study was to examine the effect of text cohesion on reading times, comprehension, and retention of colorectal cancer prevention information. English-speaking adults (50 years of age or older) were recruited from local communities. Participants were randomly assigned to read colorectal cancer prevention subtopics presented at 2 levels of text cohesion: from higher cohesion to lower cohesion, or vice versa. Reading times, word recognition, text comprehension, and recall were assessed after reading. Two weeks later, text comprehension and recall were reassessed. Forty-two adults completed the study, but five were lost to follow up. Higher text cohesion showed a significant effect on reading times and text comprehension but not on word recognition and recall. The effect of text cohesion was not found on text comprehension and recall after 2 weeks. Increasing text cohesion facilitates reading speed and comprehension of colorectal cancer prevention information. Further research on the effect of text cohesion is warranted.
Pds5 regulators segregate cohesion and condensation pathways in Saccharomyces cerevisiae
Tong, Kevin; Skibbens, Robert V.
2015-01-01
Cohesins are required both for the tethering together of sister chromatids (termed cohesion) and subsequent condensation into discrete structures—processes fundamental for faithful chromosome segregation into daughter cells. Differentiating between cohesin roles in cohesion and condensation would provide an important advance in studying chromatin metabolism. Pds5 is a cohesin-associated factor that is essential for both cohesion maintenance and condensation. Recent studies revealed that ELG1 deletion suppresses the temperature sensitivity of pds5 mutant cells. However, the mechanisms through which Elg1 may regulate cohesion and condensation remain unknown. Here, we report that ELG1 deletion from pds5-1 mutant cells results in a significant rescue of cohesion, but not condensation, defects. Based on evidence that Elg1 unloads the DNA replication clamp PCNA from DNA, we tested whether PCNA overexpression would similarly rescue pds5-1 mutant cell cohesion defects. The results indeed reveal that elevated levels of PCNA rescue pds5-1 temperature sensitivity and cohesion defects, but do not rescue pds5-1 mutant cell condensation defects. In contrast, RAD61 deletion rescues the condensation defect, but importantly, neither the temperature sensitivity nor cohesion defects exhibited by pds5-1 mutant cells. In combination, these findings reveal that cohesion and condensation are separable pathways and regulated in nonredundant mechanisms. These results are discussed in terms of a new model through which cohesion and condensation are spatially regulated. PMID:25986377
Pds5 regulators segregate cohesion and condensation pathways in Saccharomyces cerevisiae.
Tong, Kevin; Skibbens, Robert V
2015-06-02
Cohesins are required both for the tethering together of sister chromatids (termed cohesion) and subsequent condensation into discrete structures-processes fundamental for faithful chromosome segregation into daughter cells. Differentiating between cohesin roles in cohesion and condensation would provide an important advance in studying chromatin metabolism. Pds5 is a cohesin-associated factor that is essential for both cohesion maintenance and condensation. Recent studies revealed that ELG1 deletion suppresses the temperature sensitivity of pds5 mutant cells. However, the mechanisms through which Elg1 may regulate cohesion and condensation remain unknown. Here, we report that ELG1 deletion from pds5-1 mutant cells results in a significant rescue of cohesion, but not condensation, defects. Based on evidence that Elg1 unloads the DNA replication clamp PCNA from DNA, we tested whether PCNA overexpression would similarly rescue pds5-1 mutant cell cohesion defects. The results indeed reveal that elevated levels of PCNA rescue pds5-1 temperature sensitivity and cohesion defects, but do not rescue pds5-1 mutant cell condensation defects. In contrast, RAD61 deletion rescues the condensation defect, but importantly, neither the temperature sensitivity nor cohesion defects exhibited by pds5-1 mutant cells. In combination, these findings reveal that cohesion and condensation are separable pathways and regulated in nonredundant mechanisms. These results are discussed in terms of a new model through which cohesion and condensation are spatially regulated.
A two-field modified Lagrangian formulation for robust simulations of extrinsic cohesive zone models
NASA Astrophysics Data System (ADS)
Cazes, F.; Coret, M.; Combescure, A.
2013-06-01
This paper presents the robust implementation of a cohesive zone model based on extrinsic cohesive laws (i.e. laws involving an infinite initial stiffness). To this end, a two-field Lagrangian weak formulation in which cohesive tractions are chosen as the field variables along the crack's path is presented. Unfortunately, this formulation cannot model the infinite compliance of the broken elements accurately, and no simple criterion can be defined to determine the loading-unloading change of state at the integration points of the cohesive elements. Therefore, a modified Lagrangian formulation using a fictitious cohesive traction instead of the classical cohesive traction as the field variable is proposed. Thanks to this change of variable, the cohesive law becomes an increasing function of the equivalent displacement jump, which eliminates the problems mentioned previously. The ability of the proposed formulations to simulate fracture accurately and without field oscillations is investigated through three numerical test examples.
Social cohesion and self-rated health: The moderating effect of neighborhood physical disorder.
Bjornstrom, Eileen E S; Ralston, Margaret L; Kuhl, Danielle C
2013-12-01
Using data from the Los Angeles Family and Neighborhood Survey and its companion datasets, we examined how neighborhood disorder, perceived danger and both individually perceived and contextually measured neighborhood social cohesion are associated with self-rated health. Results indicate that neighborhood disorder is negatively associated with health and the relationship is explained by perceived cohesion and danger, which are both also significant predictors of health. Further, individually perceived cohesion emerges as a more important explanation of self-rated health than neighborhood-level social cohesion. Finally, neighborhood disorder and perceived cohesion interact to influence health, such that cohesion is especially beneficial when residents live in neighborhoods characterized by low to moderate disorder; once disorder is at high levels, cohesion no longer offers protection against poor health. We interpret our findings as they relate to prior research on neighborhoods, psychosocial processes, and health, and discuss their implications for intervention efforts that address disorder in urban communities.
Relating Cohesive Zone Model to Linear Elastic Fracture Mechanics
NASA Technical Reports Server (NTRS)
Wang, John T.
2010-01-01
The conditions required for a cohesive zone model (CZM) to predict a failure load of a cracked structure similar to that obtained by a linear elastic fracture mechanics (LEFM) analysis are investigated in this paper. This study clarifies why many different phenomenological cohesive laws can produce similar fracture predictions. Analytical results for five cohesive zone models are obtained, using five different cohesive laws that have the same cohesive work rate (CWR-area under the traction-separation curve) but different maximum tractions. The effect of the maximum traction on the predicted cohesive zone length and the remote applied load at fracture is presented. Similar to the small scale yielding condition for an LEFM analysis to be valid. the cohesive zone length also needs to be much smaller than the crack length. This is a necessary condition for a CZM to obtain a fracture prediction equivalent to an LEFM result.
Supporting students' learning in the domain of computer science
NASA Astrophysics Data System (ADS)
Gasparinatou, Alexandra; Grigoriadou, Maria
2011-03-01
Previous studies have shown that students with low knowledge understand and learn better from more cohesive texts, whereas high-knowledge students have been shown to learn better from texts of lower cohesion. This study examines whether high-knowledge readers in computer science benefit from a text of low cohesion. Undergraduate students (n = 65) read one of four versions of a text concerning Local Network Topologies, orthogonally varying local and global cohesion. Participants' comprehension was examined through free-recall measure, text-based, bridging-inference, elaborative-inference, problem-solving questions and a sorting task. The results indicated that high-knowledge readers benefited from the low-cohesion text. The interaction of text cohesion and knowledge was reliable for the sorting activity, for elaborative-inference and for problem-solving questions. Although high-knowledge readers performed better in text-based and in bridging-inference questions with the low-cohesion text, the interaction of text cohesion and knowledge was not reliable. The results suggest a more complex view of when and for whom textual cohesion affects comprehension and consequently learning in computer science.
ERIC Educational Resources Information Center
Crossley, Scott A.; Kyle, Kristopher; McNamara, Danielle S.
2016-01-01
An important topic in writing research has been the use of cohesive features. Much of this research has focused on local and text cohesion. The few studies that have studied global cohesion have been restricted to first language writing. This study investigates the development of local, global, and text cohesion in the writing of 57 language (L2)…
The Efficacy of ’Don’t Ask, Don’t Tell’
2009-01-01
psychologists explored the concepts, experimental and cor- relation evidence supported dividing cohesion into two distinct types: social cohesion and task...cohesion. Social cohesion is the nature and quality of the emotional bonds within a group—the degree to which members spend time together, like...along (that is, has high social cohesion ) would perform better. Almost counterintuitively, it has been shown that in some situations, high social
The Impact of Drug Abuse on Tank Crew Cohesion.
1982-08-01
social cohesion ). Examination ef modal scores on the Cohesion Questions indicated that similarity or difference in drug use pattern influenced the...demography, drug use and social cohesion . The AFFIL scores were divided into two groups: Hi AFFEL and Lo AFFIL. The Hi AFFIL group was comprised of...difference in usage pattern, the social cohesion questions were slightly more sensitive to simple similarity in drug use pattern than the job-related
Chao, Shiau-Fang
2016-09-01
This investigation examined whether community cohesion mediates or moderates the relationship between outdoor activities and depressive symptoms in older adults displaced by Typhoon Morakot in Taiwan. This cross-sectional study included 292 adults aged 65 years or older who were relocated to permanent houses after Typhoon Morakot damaged their homes on 8th August 2009. Multiple regression analysis was applied to test the role of community cohesion on the association between outdoor activities and depressive symptoms. The sample of displaced older adults displayed higher prevalence of depressive symptoms than the average for community dwelling older people in Taiwan. Community cohesion fully mediated the relationship between outdoor activities and depressive symptoms. Community cohesion also moderated the relationship between outdoor activities and depressive symptoms. Community cohesion occupies a key role on the link between outdoor activities and depressive symptoms. Participation in outdoor activities was associated positively with community cohesion, while high community cohesion was related negatively to depressive symptoms. Additionally, the benefit of outdoor activities to fewer depressive symptoms only manifested in older adults with high community cohesion. Programs and services should be designed to enhance community cohesion in order to maximize the benefit of outdoor activities to the mental health of displaced older adults after natural disasters.
Mitchell, Darcy B; Szczerepa, Alexandra; Hauser-Cram, Penny
2016-01-01
Family cohesion relates to positive outcomes for both parents and children. Maintaining cohesion may be especially challenging for families of adolescents with developmental disabilities, yet this has been studied infrequently in this group. We investigated cohesion in these families, particularly with respect to partner stress, using the notion of the 'spillover effect' as a model. Adolescents with disabilities and their parents participated. Parents reported on teen adaptive and problem behaviours and on marital satisfaction, parenting stress, and family cohesion. The stress of one partner was tested as a predictor of the quality of family cohesion reported by the other. Adolescent behaviour problems were negative predictors of family cohesion in mothers, and marital satisfaction positively predicted cohesion for both parents. Above other factors, greater partner stress predicted poorer family cohesion for both fathers and mothers. Marital satisfaction acted as a suppressor of this relation. To improve the overall climate of families, care providers should take into consideration individual relationships, including the marital relationship. In addition, the possibility of spillover from one individual to another should be recognized as a factor in family functioning. Family-centred practices are likely to lead to greater feelings of cohesion and overall better individual and family well-being. Copyright © 2015 Elsevier Ltd. All rights reserved.
The influence of perceived family support on post surgery recovery.
Cardoso-Moreno, M J; Tomás-Aragones, L
2017-01-01
The objective of this work was to investigate the possible relationship between perceived family support, levels of cortisol and post surgery recovery. The study sample comprised 42 patients that were due to undergo open cholecystectomy surgery in a Regional Health Authority Reference Centre of the Autonomous Community of Extremadura in Spain. The FACES-II questionnaire was used for the evaluation of perceived family support and to measure the three fundamental dimensions of perceived family behaviour: cohesion, adaptability and family type. The day before surgery, a sample of saliva was taken from each subject in order to determine the level of cortisol. Results showed a clear relationship between family support and recovery. Patients with higher scores on the Cohesion Scale demonstrated better post surgery recovery (F = 8.8; gl = 40; p = .005). A relationship between levels of cortisol, perceived family support and recovery was also revealed. Patients with lower scores on the Cohesion scale and higher cortisol levels demonstrated poorer post surgery recovery (F = 10.96; gl = 40; p = .006). These results are coherent with other studies that have highlighted the beneficial effects of perceived family support on mental and physical health.
The Index cohesive effect on stock market correlations
NASA Astrophysics Data System (ADS)
Shapira, Y.; Kenett, D. Y.; Ben-Jacob, E.
2009-12-01
We present empirical examination and reassessment of the functional role of the market Index, using datasets of stock returns for eight years, by analyzing and comparing the results for two very different markets: 1) the New York Stock Exchange (NYSE), representing a large, mature market, and 2) the Tel Aviv Stock Exchange (TASE), representing a small, young market. Our method includes special collective (holographic) analysis of stock-Index correlations, of nested stock correlations (including the Index as an additional ghost stock) and of bare stock correlations (after subtraction of the Index return from the stocks returns). Our findings verify and strongly substantiate the assumed functional role of the index in the financial system as a cohesive force between stocks, i.e., the correlations between stocks are largely due to the strong correlation between each stock and the Index (the adhesive effect), rather than inter-stock dependencies. The Index adhesive and cohesive effects on the market correlations in the two markets are presented and compared in a reduced 3-D principal component space of the correlation matrices (holographic presentation). The results provide new insights into the interplay between an index and its constituent stocks in TASE-like versus NYSE-like markets.
Antimitochondrial Autoantibodies in Pemphigus Vulgaris
Marchenko, Steve; Chernyavsky, Alexander I.; Arredondo, Juan; Gindi, Vivian; Grando, Sergei A.
2010-01-01
A loss of epidermal cohesion in pemphigus vulgaris (PV) results from autoantibody action on keratinocytes (KCs) activating the signaling kinases and executioner caspases that damage KCs, causing their shrinkage, detachment from neighboring cells, and rounding up (apoptolysis). In this study, we found that PV antibody binding leads to activation of epidermal growth factor receptor kinase, Src, p38 MAPK, and JNK in KCs with time pattern variations from patient to patient. Both extrinsic and intrinsic apoptotic pathways were also activated. Although Fas ligand neutralizing antibody could inhibit the former pathway, the mechanism of activation of the latter remained unknown. PV antibodies increased cytochrome c release, suggesting damage to mitochondria. The immunoblotting experiments revealed penetration of PVIgG into the subcellular mitochondrial fraction. The antimitochondrial antibodies from different PV patients recognized distinct combinations of antigens with apparent molecular sizes of 25, 30, 35, 57, 60, and 100 kDa. Antimitochondrial antibodies were pathogenic because their absorption abolished the ability of PVIgG to cause keratinocyte detachment both in vitro and in vivo. The downstream signaling of antimitochondrial antibodies involved JNK and late p38 MAPK activation, whereas the signaling of anti-desmoglein 3 (Dsg3) antibody involved JNK and biphasic p38 MAPK activation. Using KCs grown from Dsg3−/− mice, we determined that Dsg3 did not serve as a surrogate antigen allowing antimitochondrial antibodies to enter KCs. The PVIgG-induced activation of epidermal growth factor receptor and Src was affected neither in Dsg3−/− KCs nor due to absorption of antimitochondrial antibodies. These results demonstrated that apoptolysis in PV is a complex process initiated by at least three classes of autoantibodies directed against desmosomal, mitochondrial, and other keratinocyte self-antigens. These autoantibodies synergize with the proapoptotic serum and tissue factors to trigger both extrinsic and intrinsic pathways of cell death and break the epidermal cohesion, leading to blisters. Further elucidation of the primary signaling events downstream of PV autoantigens will be crucial for the development of a more successful therapy for PV patients. PMID:20007702
Written cohesion in children with and without language learning disabilities.
Koutsoftas, Anthony D; Petersen, Victoria
2017-09-01
Cohesion refers to the linguistic elements of discourse that contribute to its continuity and is an important element to consider as part of written language intervention, especially in children with language learning disabilities (LLD). There is substantial evidence that children with LLD perform more poorly than typically developing (TD) peers on measures of cohesion in spoken language and on written transcription measures; however, there is far less research comparing groups on cohesion as a measure of written language across genres. The current study addresses this gap through the following two aims. First, to describe and compare cohesion in narrative and expository writing samples of children with and without language learning disabilities. Second, to relate measures of cohesion to written transcription and translation measures, oral language, and writing quality. Fifty intermediate-grade children produced one narrative and one expository writing sample from which measures of written cohesion were obtained. These included the frequency, adequacy and complexity of referential and conjunctive ties. Expository samples resulted in more complex cohesive ties and children with TD used more complex ties than peers with LLD. Different relationships among cohesion measures and writing were observed for narrative verse expository samples. Findings from this study demonstrate cohesion as a discourse-level measure of written transcription and how the use of cohesion can vary by genre and group (LLD, TD). Clinical implications for assessment, intervention, and future research are provided. © 2016 Royal College of Speech and Language Therapists.
Ultimate pier and contraction scour prediction in cohesive soils at selected bridges in Illinois
Straub, Timothy D.; Over, Thomas M.; Domanski, Marian M.
2013-01-01
The Scour Rate In COhesive Soils-Erosion Function Apparatus (SRICOS-EFA) method includes an ultimate scour prediction that is the equilibrium maximum pier and contraction scour of cohesive soils over time. The purpose of this report is to present the results of testing the ultimate pier and contraction scour methods for cohesive soils on 30 bridge sites in Illinois. Comparison of the ultimate cohesive and noncohesive methods, along with the Illinois Department of Transportation (IDOT) cohesive soil reduction-factor method and measured scour are presented. Also, results of the comparison of historic IDOT laboratory and field values of unconfined compressive strength of soils (Qu) are presented. The unconfined compressive strength is used in both ultimate cohesive and reduction-factor methods, and knowing how the values from field methods compare to the laboratory methods is critical to the informed application of the methods. On average, the non-cohesive method results predict the highest amount of scour, followed by the reduction-factor method results; and the ultimate cohesive method results predict the lowest amount of scour. The 100-year scour predicted for the ultimate cohesive, noncohesive, and reduction-factor methods for each bridge site and soil are always larger than observed scour in this study, except 12% of predicted values that are all within 0.4 ft of the observed scour. The ultimate cohesive scour prediction is smaller than the non-cohesive scour prediction method for 78% of bridge sites and soils. Seventy-six percent of the ultimate cohesive predictions show a 45% or greater reduction from the non-cohesive predictions that are over 10 ft. Comparing the ultimate cohesive and reduction-factor 100-year scour predictions methods for each bridge site and soil, the scour predicted by the ultimate cohesive scour prediction method is less than the reduction-factor 100-year scour prediction method for 51% of bridge sites and soils. Critical shear stress remains a needed parameter in the ultimate scour prediction for cohesive soils. The unconfined soil compressive strength measured by IDOT in the laboratory was found to provide a good prediction of critical shear stress, as measured by using the erosion function apparatus in a previous study. Because laboratory Qu analyses are time-consuming and expensive, the ability of field-measured Rimac data to estimate unconfined soil strength in the critical shear–soil strength relation was tested. A regression analysis was completed using a historic IDOT dataset containing 366 data pairs of laboratory Qu and field Rimac measurements from common sites with cohesive soils. The resulting equations provide a point prediction of Qu, given any Rimac value with the 90% confidence interval. The prediction equations are not significantly different from the identity Qu = Rimac. The alternative predictions of ultimate cohesive scour presented in this study assume Qu will be estimated using Rimac measurements that include computed uncertainty. In particular, the ultimate cohesive predicted scour is greater than observed scour for the entire 90% confidence interval range for predicting Qu at the bridges and soils used in this study, with the exception of the six predicted values that are all within 0.6 ft of the observed scour.
Lipman, Ellen L; Waymouth, Marjorie; Gammon, Tara; Carter, Patricia; Secord, Margaret; Leung, Olivia; Mills, Brenda; Hicks, Frances
2007-10-01
Single mothers are at increased risk of psychosocial disadvantage, social isolation and physical and mental health difficulties. The authors present (1) the results of group cohesion assessments completed by mothers participating in a trial of community-based support/education groups, and (2) assessments of the association between group cohesion ratings and intervention outcomes of maternal self-evaluations of well-being (mood, self-esteem, and social support) and parenting. Mothers participating in groups completed the Group Atmosphere Scale, a measure of group cohesion, post-group. Overall, most participants provided strong ratings of group cohesion. Significant associations were found between group cohesion and specific positive outcomes. This suggests a positive association between group cohesion and mood, self-esteem, social support, and parenting, in this trial.
Factors Related to Group Cohesiveness.
ERIC Educational Resources Information Center
Roark, Albert E.; Sharah, Hussein S.
1989-01-01
Investigated the relationship of group cohesiveness to empathy, self-disclosure, acceptance, and trust, and compared three different groups (personal growth, driving under the influence, psychotherapy), with a total of 65 subjects, on measures of cohesiveness. Found all factors correlated significantly with cohesiveness and with one another.…
Cano, Miguel Ángel; Sánchez, Mariana; Rojas, Patria; Ramírez-Ortiz, Daisy; Polo, Katherine L; Romano, Eduardo; De La Rosa, Mario
2018-03-21
This study examined (a) the direct association of family cohesion on alcohol use severity among adult Hispanic immigrants; (b) the indirect association of family cohesion on alcohol use severity via social support; and (c) if gender moderates the direct and indirect associations between family cohesion and alcohol use severity. Mediation and moderation analyses were conducted on a cross-sectional sample of 411 (men = 222, women = 189) participants from Miami-Dade, Florida. Findings indicate that higher family cohesion was directly associated with higher social support and lower alcohol use severity. Higher social support was also directly associated with lower alcohol use severity. Additionally, family cohesion had an indirect association with alcohol use severity via social support. Moderation analyses indicated that gender moderated the direct association between family cohesion and alcohol use severity, but did not moderate the indirect association. Some potential clinical implications may be that strengthening family cohesion may enhance levels of social support, and in turn, lower alcohol use severity among adult Hispanic immigrants. Furthermore, strengthening family cohesion may be especially beneficial to men in efforts to lower levels of alcohol use severity.
A sign of the times: To have or to be? Social capital or social cohesion?
Carrasco, Maria A; Bilal, Usama
2016-06-01
Among various social factors associated with health behavior and disease, social cohesion has not captured the imagination of public health researchers as much as social capital as evidenced by the subsuming of social cohesion into social capital and the numerous studies analyzing social capital and the comparatively fewer articles analyzing social cohesion and health. In this paper we provide a brief overview of the evolution of the conceptualization of social capital and social cohesion and we use philosopher Erich Fromm's distinction between "having" and "being" to understand the current research focus on capital over cohesion. We argue that social capital is related to having while social cohesion is related to being and that an emphasis on social capital leads to individualizing tendencies that are antithetical to cohesion. We provide examples drawn from the literature where this conflation of social capital and cohesion results in non-concordant definitions and subsequent operationalization of these constructs. Beyond semantics, the practical implication of focusing on "having" vs. "being" include an emphasis on understanding how to normalize groups and populations rather than providing those groups space for empowerment and agency leading to health. Published by Elsevier Ltd.
Don’t Ask, Don’t Tell: Failing in Strategic Leadership
2007-03-30
another example of where the results might be useful. Even if 7 one accepts the fact that task cohesion overrides social cohesion as a major...it can be inferred that social cohesion is still an important factor in combat. At this point the important question becomes whether openly gay...Gateway, 1993), 57. 17 39 Social cohesion refers to emotional bonds and friendship, and is distinguished from task cohesion which refers to a group’s
Interactive effects of team cohesion on perceived efficacy in semi-professional sport.
Marcos, Francisco Miguel Leo; Miguel, Pedro Antonio Sánchez; Oliva, David Sánchez; Calvo, Tomás García
2010-01-01
The present study examined the relationships among cohesion, self-efficacy, coaches' perceptions of their players' efficacy at the individual level and athletes' perceptions of their teammates' efficacy. Participants (n = 76) recruited from four semi- professional soccer and basketball teams completed cohesiveness and efficacy questionnaires who. Data were analyzed through a correlational methodology. Results indicated significant correlations between self-efficacy and task cohesion and social cohesion. Regression analysis results suggest task cohesion positively related to coaches and teammate's perception of efficacy. These results have implications for practitioners in terms of the importance of team building to enhance team cohesion and feelings of efficacy. Key pointsThis paper increases the knowledge about soccer and basketball match analysis.Give normative values to establish practice and match objectives.Give applications ideas to connect research with coaches' practice.
Rotational Failure of Rubble-pile Bodies: Influences of Shear and Cohesive Strengths
NASA Astrophysics Data System (ADS)
Zhang, Yun; Richardson, Derek C.; Barnouin, Olivier S.; Michel, Patrick; Schwartz, Stephen R.; Ballouz, Ronald-Louis
2018-04-01
The shear and cohesive strengths of a rubble-pile asteroid could influence the critical spin at which the body fails and its subsequent evolution. We present results using a soft-sphere discrete element method to explore the mechanical properties and dynamical behaviors of self-gravitating rubble piles experiencing increasing rotational centrifugal forces. A comprehensive contact model incorporating translational and rotational friction and van der Waals cohesive interactions is developed to simulate rubble-pile asteroids. It is observed that the critical spin depends strongly on both the frictional and cohesive forces between particles in contact; however, the failure behaviors only show dependence on the cohesive force. As cohesion increases, the deformation of the simulated body prior to disruption is diminished, the disruption process is more abrupt, and the component size of the fissioned material is increased. When the cohesive strength is high enough, the body can disaggregate into similar-size fragments, which could be a plausible mechanism to form asteroid pairs or active asteroids. The size distribution and velocity dispersion of the fragments in high-cohesion simulations show similarities to the disintegrating asteroid P/2013 R3, indicating that this asteroid may possess comparable cohesion in its structure and experience rotational fission in a similar manner. Additionally, we propose a method for estimating a rubble pile’s friction angle and bulk cohesion from spin-up numerical experiments, which provides the opportunity for making quantitative comparisons with continuum theory. The results show that the present technique has great potential for predicting the behaviors and estimating the material strengths of cohesive rubble-pile asteroids.
Mathieu, John E; Kukenberger, Michael R; D'Innocenzo, Lauren; Reilly, Greg
2015-05-01
Despite the lengthy history of team cohesion-performance research, little is known about their reciprocal relationships over time. Using meta-analysis, we synthesize findings from 17 CLP design studies, and analyze their results using SEM. Results support that team cohesion and performance are related reciprocally with each other over time. We then used longitudinal data from 205 members of 57 student teams who competed in a complex business simulation over 10 weeks, to test: (a) whether team cohesion and performance were related reciprocally over multiple time periods, (b) the relative magnitude of those relationships, and (c) whether they were stable over time. We also considered the influence of team members' academic competence and degree of shared leadership on these dynamics. As anticipated, cohesion and performance were related positively, and reciprocally, over time. However, the cohesion → performance relationship was significantly higher than the performance → cohesion relationship. Moreover, the cohesion → performance relationship grew stronger over time whereas the performance → cohesion relationship remained fairly consistent over time. As expected, shared leadership related positively to team cohesion but not directly to their performance; whereas average team member academic competence related positively to team performance but was unrelated to team cohesion. Finally, we conducted and report a replication using a second sample of students competing in a business simulation. Our earlier substantive relationships were mostly replicated, and we illustrated the dynamic temporal properties of shared leadership. We discuss these findings in terms of theoretical importance, applied implications, and directions for future research. (c) 2015 APA, all rights reserved.
Sub-10-micrometer toughening and crack tip toughness of dental enamel.
Ang, Siang Fung; Schulz, Anja; Pacher Fernandes, Rodrigo; Schneider, Gerold A
2011-04-01
In previous studies, enamel showed indications to occlude small cracks in-vivo and exhibited R-curve behaviors for bigger cracks ex-vivo. This study quantifies the crack tip's toughness (K(I0),K(III0)), the crack's closure stress and the cohesive zone size at the crack tip of enamel and investigates the toughening mechanisms near the crack tip down to the length scale of a single enamel crystallite. The crack-opening-displacement (COD) profile of cracks induced by Vickers indents on mature bovine enamel was studied using atomic force microscopy (AFM). The mode I crack tip toughness K(I0) of cracks along enamel rod boundaries and across enamel rods exhibit a similar range of values: K(I0,Ir)=0.5-1.6MPa m(0.5) (based on Irwin's 'near-field' solution) and K(I0,cz)=0.8-1.5MPa m(0.5) (based on the cohesive zone solution of the Dugdale-Muskhelishvili (DM) crack model). The mode III crack tip toughness K(III0,Ir) was computed as 0.02-0.15MPa m(0.5). The crack-closure stress at the crack tip was computed as 163-770 MPa with a cohesive zone length and width 1.6-10.1μm and 24-44 nm utilizing the cohesive zone solution. Toughening elements were observed under AFM and SEM: crack bridging due to protein ligament and hydroxyapatite fibres (micro- and nanometer scale) as well as microcracks were identified. Crown Copyright © 2010. Published by Elsevier Ltd. All rights reserved.
STRESS AND FAILURE ANALYSIS OF RAPIDLY ROTATING ASTEROID (29075) 1950 DA
DOE Office of Scientific and Technical Information (OSTI.GOV)
Hirabayashi, Masatoshi; Scheeres, Daniel J., E-mail: masatoshi.hirabayashi@colorado.edu
Rozitis et al. recently reported that near-Earth asteroid (29075) 1950 DA, whose bulk density ranges from 1.0 g cm{sup –3} to 2.4 g cm{sup –3}, is a rubble pile and requires a cohesive strength of at least 44-76 Pa to keep from failing due to its fast spin period. Since their technique for giving failure conditions required the averaged stress over the whole volume, it discarded information about the asteroid's failure mode and internal stress condition. This paper develops a finite element model and revisits the stress and failure analysis of 1950 DA. For the modeling, we do not consider material hardening andmore » softening. Under the assumption of an associated flow rule and uniform material distribution, we identify the deformation process of 1950 DA when its constant cohesion reaches the lowest value that keeps its current shape. The results show that to avoid structural failure the internal core requires a cohesive strength of at least 75-85 Pa. It suggests that for the failure mode of this body, the internal core first fails structurally, followed by the surface region. This implies that if cohesion is constant over the whole volume, the equatorial ridge of 1950 DA results from a material flow going outward along the equatorial plane in the internal core, but not from a landslide as has been hypothesized. This has additional implications for the likely density of the interior of the body.« less
Intact Discourse Cohesion and Coherence Following Bilateral Ventromedial Prefrontal Cortex
ERIC Educational Resources Information Center
Kurczek, Jake; Duff, Melissa C.
2012-01-01
Discourse cohesion and coherence give communication its continuity providing the grammatical and lexical links that hold an utterance or text together and give it meaning. Researchers often link cohesion and coherence deficits to the frontal lobes by drawing attention to frontal lobe dysfunction in populations where discourse cohesion and…
ERIC Educational Resources Information Center
Zaccaro, Stephen J.
1991-01-01
Presents results of a study contrasting different forms of group cohesiveness in a student military organization. Reports that task cohesiveness was more strongly associated with lower role uncertainty, higher individual performance, and lower absenteeism than was interpersonal cohesiveness. Concludes that data provide evidence for a…
Building a Board that Sticks Together
ERIC Educational Resources Information Center
Wilson, E. B.
2006-01-01
High-performing boards operating at a distinguishable level of excellence, all exhibit a culture of cohesiveness. And a compelling codicil is that these boards did not deliberately set out to become cohesive and perhaps do not even know they are cohesive. This article examines the value of cohesion to university governing boards, explicitly…
Soldiers Have to Eat Soup Together for a Long Time
2007-03-10
negatively impacted unit cohesion. The definition of cohesion used for this project is that of “ social cohesion ” or trust based on shared successes...fight.” 9 Napoleon was referring to social cohesion or trust based on shared successes during training and operations. The DoD’s mobilization
CrossTalk, The Journal of Defense Software Engineering. Volume 28 Number 1. Jan/Feb 2015
2015-02-01
5.63 1.03 Positive Gain 1.19 42% 1.10 27% 1.20 31% 0.44 12% Table 7. Group 1 & 2 Pretest and Posttest Means and Gain Scores. The one ...linked to team performance [6][7][8] and is considered one of the most important small group variables [9] with cohesion-performance being driven by...increased team cohesion. Measuring Cohesion In order to measure team cohesion, one must first understand the correlated cohesion constructs. The Group
Lozano, Paula; Fleischer, Nancy L; Moore, Spencer; Shigematsu, Luz Myriam Reynales; Santillán, Edna Arillo; Thrasher, James F
2016-07-01
The aim of this study was to examine the separate and combined relationships of neighborhood social norms and neighborhood social cohesion with smoking behavior in a cohort of adult Mexican smokers. Neighborhood anti-smoking norms were measured as the proportion of residents in each neighborhood who believed that society disapproves of smoking. Perceived social cohesion was measured using a 5-item cohesion scale and aggregated to the neighborhood level. Higher neighborhood anti-smoking norms were associated with less successful quitting. Neighborhood social cohesion modified the relationship between neighborhood social norms and two smoking behaviors: smoking intensity and quit attempts. Residents of neighborhoods with weaker anti-smoking norms and higher social cohesion had lower smoking intensity and more quit attempts than residents living in other areas. Social cohesion may help buffer smoking behavior in areas with weak social norms. Copyright © 2016 Elsevier Ltd. All rights reserved.
Bromell, Lea; Cagney, Kathleen A.
2014-01-01
This study investigated the impact of neighborhood social cohesion on the perceived companionship of nearly 1,500 community-dwelling older adults from the Neighborhood, Organization, Aging and Health project (NOAH), a Chicago-based study of older adult well-being in the neighborhood context. We hypothesized that the relationship between neighborhood-level social cohesion and individual residents’ reports of companionship would be more pronounced among those who lived alone than those who resided with others. Controlling for age, gender, education, race, marital status, length of neighborhood residence, and self-rated health, neighborhood social cohesion predicted companionship among those who lived alone; for a one-unit increase in neighborhood social cohesion, the odds of reporting companionship increased by half. In contrast, social cohesion did not predict the companionship of those who resided with others. The results suggest that older adults who live alone particularly profit from the benefits of socially cohesive neighborhood environments. PMID:24860203
Lexical Cohesion and Specialized Knowledge in Science and Popular Science Texts.
ERIC Educational Resources Information Center
Myers, Greg
1991-01-01
Examines cohesion in the introductions to some scientific articles and compares the patterns to those from popularizations. Discusses a computational model of cohesion. Argues that readers of scientific articles must have a knowledge of lexical relations to see the implicit cohesion, whereas readers of popularizations must see the cohesive…
THE EFFECTS OF GAMMA IRRADIATION ON THE RHEOLOGICAL PROPERTIES OF WHEAT GLUTEN (in Japanese)
DOE Office of Scientific and Technical Information (OSTI.GOV)
Doguchi, M.; Yokoyama, Y.; Odaka, I.
Wheat gluten samples were x irradiated at doses from 4 x 10/sup 6/ to 10/ sup 7/ rep, and the flours, prepared by mixing the gluten samples with wheat starch, were subjected to rheological tests. The apparent viscosities obtained by the McMichael viscometer and the maximum viscosity of the alkaline viscogram tended to decrease with increasing dosage. Farinograms and mixograms, obtained by the constant water absorption method, showed that the dough development curves changed their shape after irradiation; for example, the maximum resistance to mixing and the time to reach this maximum decreased. When the dosage was increased to moremore » than 3 x 10/sup 6/ rep, the samples lost the unique elastic and cohesive properties of wheat gluten. Moreover, as the irradiation dose increased, the extensigrams showed a notable decrease in resistance and a slight decrease in extensibility; such changes were not observed after treatment with either sulfhydryl-blocking reagents or by disulfide bond-splitting reagents. Gluten was so denatured at 10/sup 7/ rep that a dough could not be prepared from the sample. These results show that the changes of the rheological properties of wheat gluten induced by x irradiation are due to a structural change of the protein molecule of gluten rather than the breaking of disulfide bonds or blocking of sulfhydryl groups. (BBB)« less
Cohesiveness and hydrodynamic properties of young drinking water biofilms.
Abe, Yumiko; Skali-Lami, Salaheddine; Block, Jean-Claude; Francius, Grégory
2012-03-15
Drinking water biofilms are complex microbial systems mainly composed of clusters of different size and age. Atomic force microscopy (AFM) measurements were performed on 4, 8 and 12 weeks old biofilms in order to quantify the mechanical detachment shear stress of the clusters, to estimate the biofilm entanglement rate ξ. This AFM approach showed that the removal of the clusters occurred generally for mechanical shear stress of about 100 kPa only for clusters volumes greater than 200 μm3. This value appears 1000 times higher than hydrodynamic shear stress technically available meaning that the cleaning of pipe surfaces by water flushing remains always incomplete. To predict hydrodynamic detachment of biofilm clusters, a theoretical model has been developed regarding the averaging of elastic and viscous stresses in the cluster and by including the entanglement rate ξ. The results highlighted a slight increase of the detachment shear stress with age and also the dependence between the posting of clusters and their volume. Indeed, the experimental values of ξ allow predicting biofilm hydrodynamic detachment with same order of magnitude than was what reported in the literature. The apparent discrepancy between the mechanical and the hydrodynamic detachment is mainly due to the fact that AFM mechanical experiments are related to the clusters local properties whereas hydrodynamic measurements reflected the global properties of the whole biofilm. Copyright © 2011 Elsevier Ltd. All rights reserved.
Cohesion energetics of carbon allotropes: Quantum Monte Carlo study
DOE Office of Scientific and Technical Information (OSTI.GOV)
Shin, Hyeondeok; Kang, Sinabro; Koo, Jahyun
2014-03-21
We have performed quantum Monte Carlo calculations to study the cohesion energetics of carbon allotropes, including sp{sup 3}-bonded diamond, sp{sup 2}-bonded graphene, sp–sp{sup 2} hybridized graphynes, and sp-bonded carbyne. The computed cohesive energies of diamond and graphene are found to be in excellent agreement with the corresponding values determined experimentally for diamond and graphite, respectively, when the zero-point energies, along with the interlayer binding in the case of graphite, are included. We have also found that the cohesive energy of graphyne decreases systematically as the ratio of sp-bonded carbon atoms increases. The cohesive energy of γ-graphyne, the most energetically stablemore » graphyne, turns out to be 6.766(6) eV/atom, which is smaller than that of graphene by 0.698(12) eV/atom. Experimental difficulty in synthesizing graphynes could be explained by their significantly smaller cohesive energies. Finally, we conclude that the cohesive energy of a newly proposed graphyne can be accurately estimated with the carbon–carbon bond energies determined from the cohesive energies of graphene and three different graphynes considered here.« less
Investigation of the mechanical properties of organoplastic under shock wave loading conditions
NASA Astrophysics Data System (ADS)
Bragov, A. M.; Igumnov, L. A.; Konstantinov, A. Yu; Lomunov, A. K.
2018-04-01
The paper presents results of dynamic tests of a typical representative of new composite and damping materials: organoplastics. Compression testing was performed using the traditional Kolsky method and its original modification. The strength and deformation properties of organoplastics under conditions of uniaxial stress and uniaxial deformation were studied. When the organoplastic is compressed transversely to the Kevlar fabric layers under conditions of a uniaxial stress state, the material begins to break down (to lose the layer cohesion) at a stress of about 200 MPa, while under the conditions of uniaxial strain, it retains its apparent integrity at stresses up to 500 MPa. The small value of the lateral thrust factor indicates a large internal strength of the material in tension in the radial direction.
Verification of surface preparation for adhesive bonding
NASA Technical Reports Server (NTRS)
Myers, Rodney S.
1995-01-01
A survey of solid rocket booster (SRB) production operations identified potential contaminants which might adversely affect bonding operations. Lap shear tests quantified these contaminants' effects on adhesive strength. The most potent contaminants were selected for additional studies on SRB thermal protection system (TPS) bonding processes. Test panels were prepared with predetermined levels of contamination, visually inspected using white and black light, then bonded with three different TPS materials over the unremoved contamination. Bond test data showed that white and black light inspections are adequate inspection methods for TPS bonding operations. Extreme levels of contamination (higher than expected on flight hardware) had an insignificant effect on TPS bond strengths because of the apparent insensitivity of the adhesive system to contamination effects, and the comparatively weak cohesive strength of the TPS materials.
Kim, Mi Ye; Lim, Ji Young; Chung, Grace H
2012-12-01
There is evidence that parent-child cohesion is a potentially influential factor in children's self-esteem and acculturation. However, no research to date has examined cohesion with parents as a potential pathway between Korean proficiency and self-esteem or acculturation among children from multicultural families. This study was done to address these limitations by examining whether and to what extent cohesion with parents mediated the effect of Korean proficiency on self-esteem and acculturation among children from multicultural families. Data were collected from a sample of 138 mothers and their children living in Seoul, Daegu, Kyungi province, and Kyungpook province. Multiple regression analysis was used to examine the relationships between the variables of interest. Mediation effects of cohesion with parents were tested by following the procedure recommended by Baron and Kenny (1986). Cohesion with parents partially mediated the relationship between Korean proficiency and self-esteem. For children's acculturation, the effect of Korean proficiency was partially mediated through father-child cohesion. Mother-child cohesion completely mediated the relationship between Korean proficiency and acculturation. These findings suggest that to help children from multicultural families experiencing difficulties with self-esteem or acculturation, it might be useful to develop programs that are aimed at strengthen cohesion with parents.
Happier together. Social cohesion and subjective well-being in Europe.
Delhey, Jan; Dragolov, Georgi
2016-06-01
Despite mushrooming research on "social" determinants of subjective well-being (SWB), little is known as to whether social cohesion as a collective property is among the key societal conditions for human happiness. This article fills this gap in investigating the importance of living in a cohesive society for citizens' SWB. For 27 European Union countries, it combines the newly developed Bertelsmann Foundation's Cohesion Index with individual well-being data on life evaluation and psychological functioning as surveyed in the recent European Quality of Life Survey. The main results from multi-level analyses are as follows. First, Europeans are indeed happier and psychologically healthier in more cohesive societies. Second, all three core domains of cohesion increase individuals' SWB. Third, citizens in the more affluent part of Europe feel the positivity of social cohesion more consistently than those in the less affluent part. Finally, within countries, cohesion is good for the SWB of resource-rich and resource-poor groups alike. Our findings also shed new light on the ongoing debate on economic progress and quality of life: what makes citizenries of affluent societies happier is, in the first place, their capacity to create togetherness and solidarity among their members-in other words, cohesion. © 2015 International Union of Psychological Science.
Neighborhood cohesion and daily well-being: Results from a diary study
Robinette, Jennifer W.; Charles, Susan T.; Mogle, Jacqueline A.; Almeida, David M.
2013-01-01
Neighborly cohesiveness has documented benefits for health. Furthermore, high perceived neighborhood cohesion offsets the adverse health effects of neighborhood socioeconomic adversity. One potential way neighborhood cohesion influences health is through daily stress processes. The current study uses participants (n = 2022, age 30–84 years) from The Midlife in the United States II and the National Study of Daily Experiences II, collected between 2004–2006, to examine this hypothesis using a within-person, daily diary design. We predicted that people who perceive high neighborhood cohesion are exposed to fewer daily stressors, such as interpersonal arguments, lower daily physical symptoms and negative affect, and higher daily positive affect. We also hypothesized that perceptions of neighborhood cohesion buffer declines in affective and physical well-being on days when daily stressors do occur. Results indicate that higher perceived neighborhood cohesion predicts fewer self-reported daily stressors, higher positive affect, lower negative affect, and fewer physical health symptoms. High perceived neighborhood cohesion also buffers the effects of daily stressors on negative affect, even after adjusting for other sources of social support. Results from the present study suggest interventions focusing on neighborhood cohesion may result in improved well-being and may minimize the adverse effect of daily stressors. PMID:24034965
Context matters: Community social cohesion and health behaviors in two South African areas.
Lippman, Sheri A; Leslie, Hannah H; Neilands, Torsten B; Twine, Rhian; Grignon, Jessica S; MacPhail, Catherine; Morris, Jessica; Rebombo, Dumisani; Sesane, Malebo; El Ayadi, Alison M; Pettifor, Audrey; Kahn, Kathleen
2018-03-01
Understanding how social contexts shape HIV risk will facilitate development of effective prevention responses. Social cohesion, the trust and connectedness experienced in communities, has been associated with improved sexual health and HIV-related outcomes, but little research has been conducted in high prevalence settings. We conducted population-based surveys with adults 18-49 in high HIV prevalence districts in Mpumalanga (n = 2057) and North West Province (n = 1044), South Africa. Community social cohesion scores were calculated among the 70 clusters. We used multilevel logistic regression stratified by gender to assess individual- and group-level associations between social cohesion and HIV-related behaviors: recent HIV testing, heavy alcohol use, and concurrent sexual partnerships. Group-level cohesion was protective in Mpumalanga, where perceived social cohesion was higher. For each unit increase in group cohesion, the odds of heavy drinking among men were reduced by 40% (95%CI 0.25, 0.65); the odds of women reporting concurrent sexual partnerships were reduced by 45% (95%CI 0.19, 1.04; p = 0.06); and the odds of reporting recent HIV testing were 1.6 and 1.9 times higher in men and women, respectively. We identified potential health benefits of cohesion across three HIV-related health behaviors in one region with higher overall evidence of group cohesion. There may be a minimum level of cohesion required to yield positive health effects. Copyright © 2018 Elsevier Ltd. All rights reserved.
Coach-initiated motivational climate and cohesion in youth sport.
Eys, Mark A; Jewitt, Eryn; Evans, M Blair; Wolf, Svenja; Bruner, Mark W; Loughead, Todd M
2013-09-01
The general purpose of the present study was to examine the link between cohesion and motivational climate in youth sport. The first specific objective was to determine if relationships demonstrated in previous research with adult basketball and handball participants would be replicated in a younger sample and with a more heterogeneous set of sports. The second specific objective was to examine whether sources of athlete enjoyment moderate the relationships between motivational climate and cohesion. Athletes (N = 997; 532 girls and 465 boys; Mage = 15.26 +/- 1.20 years) completed measures pertaining to coach-initiated motivational climate, cohesion, and sources of enjoyment. Bivariate and canonical correlations revealed positive correlations between perceptions of a task-involving motivational climate and both task and social cohesion, while ego-involving motivational climate was negatively related. Cluster analyses suggested that individuals perceiving a low task-involving climate and high ego-involving climate perceived their teams as less cohesive. Finally, the degree to which participants derived enjoyment through other-referenced competency served as a moderator in the motivational climate-task cohesion relationship. Specifically, the relationship between task cohesion and motivational climate was more pronounced for those individuals who were less likely to derive enjoyment through other-referenced competency. Youth athletes' perceptions of coach-initiated motivational climate are related to cohesion. This relationship is, however, moderated by the degree to which athletes derive enjoyment through other-referenced competency. Motivational climate is an important variable to consider within team-building protocols intent on developing cohesion.
Relationship between the cohesion of guest particles on the flow behaviour of interactive mixtures.
Mangal, Sharad; Gengenbach, Thomas; Millington-Smith, Doug; Armstrong, Brian; Morton, David A V; Larson, Ian
2016-05-01
In this study, we aimed to investigate the effects cohesion of small surface-engineered guest binder particles on the flow behaviour of interactive mixtures. Polyvinylpyrrolidone (PVP) - a model pharmaceutical binder - was spray-dried with varying l-leucine feed concentrations to create small surface-engineered binder particles with varying cohesion. These spray-dried formulations were characterised by their particle size distribution, morphology and cohesion. Interactive mixtures were produced by blending these spray-dried formulations with paracetamol. The resultant blends were visualised under scanning electron microscope to confirm formation of interactive mixtures. Surface coverage of paracetamol by guest particles as well as the flow behaviour of these mixtures were examined. The flow performance of interactive mixtures was evaluated using measurements of conditioned bulk density, basic flowability energy, aeration energy and compressibility. With higher feed l-leucine concentrations, the surface roughness of small binder particles increased, while their cohesion decreased. Visual inspection of the SEM images of the blends indicated that the guest particles adhered to the surface of paracetamol resulting in effective formation of interactive mixtures. These images also showed that the low-cohesion guest particles were better de-agglomerated that consequently formed a more homogeneous interactive mixture with paracetamol compared with high-cohesion formulations. The flow performance of interactive mixtures changed as a function of the cohesion of the guest particles. Interactive mixtures with low-cohesion guest binder particles showed notably improved bulk flow performance compared with those containing high-cohesion guest binder particles. Thus, our study suggests that the cohesion of guest particles dictates the flow performance of interactive mixtures. Crown Copyright © 2016. Published by Elsevier B.V. All rights reserved.
Bedform development in mixed sand-mud: The contrasting role of cohesive forces in flow and bed
NASA Astrophysics Data System (ADS)
Baas, Jaco H.; Davies, Alan G.; Malarkey, Jonathan
2013-01-01
The majority of subaqueous sediment on Earth consists of mixtures of cohesive clay and cohesionless sand and silt, but the role of cohesion on the development and stability of sedimentary bedforms is poorly understood. The results of new laboratory flume experiments on bedform development in cohesive, mixed sand-mud beds are compared with the results of previous experiments in which cohesive forces in high concentration clay flows dominated bedform development. Even though both series of mixed sand-mud experiments were conducted at similar flow velocities, the textural and structural properties of the bedforms were sufficiently different to permit the designation of key criteria for identifying bedform generation under cohesive flows against bedform generation on cohesive substrates. These criteria are essential for improving bedform size predictions in sediment transport modelling in modern sedimentary environments and for the reconstruction of depositional processes in the geological record. The current ripples developing on the cohesive, mixed sand-mud beds, with bed mud fractions of up to 18%, were significantly smaller than equivalent bedforms in noncohesive sand. Moreover, the bedform height showed a stronger inversely proportional relationship with initial bed mud fraction than the bedform wavelength. This is in contrast with the bedforms developing under the cohesive clay flows, which tend to increase in size with increasing suspended clay concentration until the flow turbulence is fully suppressed. Selective removal of clay from the mixed beds, i.e., clay winnowing, was found to be an important process, with 82-100% clay entrained into suspension after 2 h of bedform development. This winnowing process led to the development of a sand-rich armouring layer. This armouring layer is inferred to have protected the underlying mixed sand-mud from prolonged erosion, and in conjunction with strong cohesive forces in the bed may have caused the smaller size of the bedforms. Winnowing was less efficient for the bedforms developing under the cohesive clay flows, where bedforms consisting of muddy sand were more characteristic. The winnowed sand was also found to heal irregularly scoured topography, thus reestablishing classic quasitriangular bedform shapes. In cohesive flows, the bedforms had more variable shapes, and the healing process was confined to lower transitional plug flows in which strong turbulence is only present close to the sediment bed. Furthermore, the bedforms on the cohesive beds tended to form angle-of-repose cross lamination, whereas low angle cross lamination was more common in bedforms under cohesive flows. In general terms, erosional bedforms prevail when cohesive forces in the bed dominate bedform dynamics, whereas depositional bedforms prevail when cohesive forces in the flow dominate bedform dynamics. Empirical relationships between the proportion of cohesive mud in the mixed sand-mud bed and the development rate and size of the bedforms are defined for future use in field and laboratory studies.
ERIC Educational Resources Information Center
Papastamatis, Adamantios; Panitsidou, Eugenia
2009-01-01
The problems faced by a postmodern European Union, due to internationalisation of the economy, loss of competitiveness, rise in unemployment and negative demographic outcomes, call for transformations able to promote excellence in knowledge, technology and economic effectiveness, which also promote social cohesion. Thus, investment in human…
USDA-ARS?s Scientific Manuscript database
There is considerable interest to determine the threshold for aeolian dust emission on Earth and Mars. Existing schemes for threshold friction velocity are all deterministic in nature, but observations show that in the dust particle size range the threshold friction velocity scatters strongly due t...
ERIC Educational Resources Information Center
Janmaat, Jan Germen
2011-01-01
Unlike most studies on social cohesion, this study explores the concept as a real-life macro-level phenomenon. It assesses to what extent the conceptions of social cohesion suggested by several macro-level approaches represent coherent empirically observable forms of social cohesion. Additionally it discusses two perspectives on social…
Observations that Constrain the Scaling of Apparent Stress
NASA Astrophysics Data System (ADS)
McGarr, A.; Fletcher, J. B.
2002-12-01
Slip models developed for major earthquakes are composed of distributions of fault slip, rupture time, and slip velocity time function over the rupture surface, as divided into many smaller subfaults. Using a recently-developed technique, the seismic energy radiated from each subfault can be estimated from the time history of slip there and the average rupture velocity. Total seismic energies, calculated by summing contributions from all of the subfaults, agree reasonably well with independent estimates based on seismic energy flux in the far-field at regional or teleseismic distances. Two recent examples are the 1999 Izmit, Turkey and the 1999 Hector Mine, California earthquakes for which the NEIS teleseismic measurements of radiated energy agree fairly closely with seismic energy estimates from several different slip models, developed by others, for each of these events. Similar remarks apply to the 1989 Loma Prieta, 1992 Landers, and 1995 Kobe earthquakes. Apparent stresses calculated from these energy and moment results do not indicate any moment or magnitude dependence. The distributions of both fault slip and seismic energy radiation over the rupture surfaces of earthquakes are highly inhomogeneous. These results from slip models, combined with underground and seismic observations of slip for much smaller mining-induced earthquakes, can provide stronger constraint on the possible scaling of apparent stress with moment magnitude M or seismic moment. Slip models for major earthquakes in the range M6.2 to M7.4 show maximum slips ranging from 1.6 to 8 m. Mining-induced earthquakes at depths near 2000 m in South Africa are associated with peak slips of 0.2 to 0.37 m for events of M4.4 to M4.6. These maximum slips, whether derived from a slip model or directly observed underground in a deep gold mine, scale quite definitively as the cube root of the seismic moment. In contrast, peak slip rates (maximum subfault slip/rise time) appear to be scale invariant. A 1.25 m/s slip rate for one of the mining-induced earthquakes was estimated by dividing the corresponding slip observed at depth by the duration of the seismically-recorded slip pulse. Peak slip rates determined from the slip models for the major earthquakes are similar, ranging from about 0.8 to 4.8 m/s. Thus, for earthquakes in the moment magnitude range 4.4 to 7.4, the peak slip rate shows no dependence on M. Whatever variation there is in slip rate is probably due to factors related to the strength of the seismogenic rock mass such as depth. These observations support the idea that apparent stress does not vary systematically with seismic moment inasmuch as the apparent stress is determined by slip rate. Indeed, our finding that fault behavior of M4.4 earthquakes can be scaled readily to events of M greater than 7 with slips up to about 8 m suggests, quite persuasively, that the source physics for crustal earthquakes is much the same over this magnitude range. Interestingly, the mining-induced earthquakes involved brittle failure across very old pre-existing faults for which the cohesive strength is high and the pore pressure is zero, due to mining operations.
Family cohesion and pride, drinking and alcohol use disorder in Puerto Rico.
Caetano, Raul; Vaeth, Patrice A C; Canino, Glorisa
2017-01-01
The extended multigenerational family is a core value of Hispanic culture. Family cohesion/pride can have protective effects on drinking- and drug-use-related behavior among Hispanics. To examine the association between family cohesion/pride, drinking, binge drinking, and DSM-5 alcohol use disorder (AUD) in Puerto Rico. Data are from a household random sample of 1510 individuals 18-64 years of age in San Juan, Puerto Rico. Bivariate analyses showed that family cohesion/pride was not associated with the average number of drinks consumed per week but was associated with binge drinking among men. Family cohesion/pride was also associated with DSM-5 AUD. Results of the multivariate analyses were consistent with these bivariate results for DSM-5 AUD. Respondents with low (OR = 2.2, 95CL = 1.21-3.98; p < .01) and medium (OR = 1.88; 95CL = 1.12-3.14; p < .01) family cohesion/pride were more likely than those with high family cohesion/pride to have a positive diagnosis of DSM-5 AUD. More liberal drinking norms and positive attitudes toward drinking were also strong predictors of the average number of drinks consumed per week. More liberal drinking norms also predicted binge drinking, and DSM-5 AUD. Higher family cohesion/pride may have a protective effect against DSM-5 AUD. This may have practical implications for clinical and prevention programs. As long as high cohesion is not enabling drinking, these programs can enhance and support family cohesion/pride to help clients in treatment and recovery and prevent drinking problems.
Hooton, Jennifer C; Jones, Matthew D; Harris, Haggis; Shur, Jagdeep; Price, Robert
2008-09-01
The aim of this investigation was to study the influence of crystalline habit of active pharmaceutical ingredients on the cohesive-adhesive force balance within model dry powder inhaler (DPI) formulations and the corresponding affect on DPI formulation performance. The cohesive-adhesive balance (CAB) approach to colloid probe atomic force microscopy (AFM) was employed to determine the cohesive and adhesive interactions of micronized budesonide particles against the {102} and {002} faces of budesonide single crystals and crystalline substrates of different sugars (cyclodextrin, lactose, trehalose, raffinose, and xylitol), respectively. These data were used to measure the relative level of cohesion and adhesion via CAB and the possible influence on in vitro performance of a carrier-based DPI formulation. Varying the crystal habit of the drug had a significant effect on the cohesive measurement of micronized budesonide probes, with the cohesive values on the {102} faces being approximately twice that on the {002} crystal faces. However, although different CAB values were measured with the sugars with respect to the crystal faces chosen for the cohesive-based measurement, the overall influence on the rank order of the CAB values was not directly influenced. For these data sets, the CAB gradient indicated that a decrease in the dominance of the adhesive forces led to a concomitant increase in fine particle delivery, reaching a plateau as the cohesive forces became dominant. The study suggested that crystal habit of the primary drug crystals influences the cohesive interactions and the resulting force balance measurements of colloid probe CAB analysis.
Family Cohesion and Pride: Drinking and Alcohol Use Disorders in Puerto Rico
Caetano, Raul; Vaeth, Patrice A. C.; Canino, Glorisa
2017-01-01
Background The extended multigenerational family is a core value of Hispanic culture. Family cohesion/pride can have protective effects on drinking and drug use related behavior among Hispanics. Objectives To examine the association between family cohesion/pride, drinking, binge drinking, and DSM-5 alcohol use disorder in Puerto Rico. Methods Data are from a household random sample of 1510 individuals 18-64 years of age of San Juan, Puerto Rico. Results Bivariate analyses showed that family cohesion/pride was not associated with the average number of drinks consumed per week, but was associated with binge drinking among men. Family cohesion/pride was also associated with DSM-5 alcohol use disorder. Results of the multivariate analyses were consistent with these bivariate results for DSM-5 AUD. Respondents with low (OR=2.2, 95CL=1.21-3.98; p<.01) and medium (OR=1.88; 95CL=1.12-3.14; p<.01) family cohesion/pride were more likely than those with high family cohesion/pride to have a positive diagnosis of DSM-5 alcohol use disorder. More liberal drinking norms and positive attitudes towards drinking were also strong predictors of the average number of drinks consumed per week. More liberal drinking norms also predicted binge drinking, and DSM-5 AUD. Conclusions Higher family cohesion/pride may have a protective effect against DSM-5 alcohol use disorder. This may have practical implications for clinical and prevention programs. As long as high cohesion is not enabling drinking, these programs can enhance and support family cohesion/pride to help clients in treatment and recovery and prevent drinking problems. PMID:27808561
Yuma-Guerrero, Paula J; Cubbin, Catherine; von Sternberg, Kirk
2017-12-01
The purpose of this study was to determine if social cohesion mediates the effects of neighborhood and household-level socioeconomic status (SES), perceptions of neighborhood safety, and access to parks on mothers' engagement in physical activity (PA). Secondary analyses were conducted on cross-sectional data from The Geographic Research on Wellbeing (GROW) study. GROW includes survey data from a diverse sample of 2,750 California mothers. Structural equation modeling was used to test a conceptual multilevel mediation model, proposing social cohesion as a mediator of known predictors of PA. Social cohesion fully mediated the pathway from perceived neighborhood safety to mothers' PA. Social cohesion also mediated the significant relationship between neighborhood SES and PA; however, this mediation finding was not practically significant when considered in the context of the full model. Household SES was significantly positively related to both social cohesion and PA. Park access contributed significantly to social cohesion but not directly to PA Social cohesion did not significantly mediate relationships between park access or household SES and PA. There is a need for public health interventions to improve engagement in PA among individuals and neighborhoods with lower levels of socioeconomic resources. Interventions that create social cohesion within neighborhoods may have positive effects on mothers' PA, particularly in neighborhoods perceived as unsafe.
Contributions of Self-Explanation to Comprehension of High- and Low-Cohesion Texts
ERIC Educational Resources Information Center
Ozuru, Yasuhiro; Briner, Stephen; Best, Rachel; McNamara, Danielle S.
2010-01-01
This study examined how the contribution of self-explanation to science text comprehension is affected by the cohesion of a text at a local level. Psychology undergraduates read and self-explained a science text with either low or high local cohesion. Local cohesion was manipulated by the presence or absence of connectives and referential words or…
Revealing the Hidden Relationship by Sparse Modules in Complex Networks with a Large-Scale Analysis
Jiao, Qing-Ju; Huang, Yan; Liu, Wei; Wang, Xiao-Fan; Chen, Xiao-Shuang; Shen, Hong-Bin
2013-01-01
One of the remarkable features of networks is module that can provide useful insights into not only network organizations but also functional behaviors between their components. Comprehensive efforts have been devoted to investigating cohesive modules in the past decade. However, it is still not clear whether there are important structural characteristics of the nodes that do not belong to any cohesive module. In order to answer this question, we performed a large-scale analysis on 25 complex networks with different types and scales using our recently developed BTS (bintree seeking) algorithm, which is able to detect both cohesive and sparse modules in the network. Our results reveal that the sparse modules composed by the cohesively isolated nodes widely co-exist with the cohesive modules. Detailed analysis shows that both types of modules provide better characterization for the division of a network into functional units than merely cohesive modules, because the sparse modules possibly re-organize the nodes in the so-called cohesive modules, which lack obvious modular significance, into meaningful groups. Compared with cohesive modules, the sizes of sparse ones are generally smaller. Sparse modules are also found to have preferences in social and biological networks than others. PMID:23762457
[Effects of family cohesion and adaptability on behavioral problems in preschool children].
Wang, Yan-Ni; Xue, Hong-Li; Chen, Qian
2016-05-01
To investigate the effects of family cohesion and adaptability on behavioral problems in preschool children. The stratified cluster multistage sampling method was used to perform a questionnaire survey in the parents of 1 284 children aged 3-6 years in the urban area of Lanzhou, China. The general status questionnaire, Conners Child Behavior Checklist (Parent Symptom Question), and Family Adaptability and Cohesion Scale, Second edition, Chinese version (FACESII-CV) were used to investigate behavioral problems and family cohesion and adaptability. The overall detection rate of behavioral problems in preschool children was 17.13%. The children with different types of family cohesion had different detection rates of behavioral problems, and those with free-type family cohesion showed the highest detection rate of behavioral problems (40.2%). The children with different types of family adaptability also had different detection rates of behavioral problems, and those with stiffness type showed the highest detection rate of behavioral problems (25.1%). The behavioral problems in preschool children were negatively correlated with family cohesion and adaptability. During the growth of preschool children, family cohesion and adaptability have certain effects on the mental development of preschool children.
Arabidopsis MZT1 homologs GIP1 and GIP2 are essential for centromere architecture.
Batzenschlager, Morgane; Lermontova, Inna; Schubert, Veit; Fuchs, Jörg; Berr, Alexandre; Koini, Maria A; Houlné, Guy; Herzog, Etienne; Rutten, Twan; Alioua, Abdelmalek; Fransz, Paul; Schmit, Anne-Catherine; Chabouté, Marie-Edith
2015-07-14
Centromeres play a pivotal role in maintaining genome integrity by facilitating the recruitment of kinetochore and sister-chromatid cohesion proteins, both required for correct chromosome segregation. Centromeres are epigenetically specified by the presence of the histone H3 variant (CENH3). In this study, we investigate the role of the highly conserved γ-tubulin complex protein 3-interacting proteins (GIPs) in Arabidopsis centromere regulation. We show that GIPs form a complex with CENH3 in cycling cells. GIP depletion in the gip1gip2 knockdown mutant leads to a decreased CENH3 level at centromeres, despite a higher level of Mis18BP1/KNL2 present at both centromeric and ectopic sites. We thus postulate that GIPs are required to ensure CENH3 deposition and/or maintenance at centromeres. In addition, the recruitment at the centromere of other proteins such as the CENP-C kinetochore component and the cohesin subunit SMC3 is impaired in gip1gip2. These defects in centromere architecture result in aneuploidy due to severely altered centromeric cohesion. Altogether, we ascribe a central function to GIPs for the proper recruitment and/or stabilization of centromeric proteins essential in the specification of the centromere identity, as well as for centromeric cohesion in somatic cells.
NASA Astrophysics Data System (ADS)
Martínez, Enrique; Uberuaga, Blas P.; Wirth, Brian D.
2017-08-01
Due to their low sputtering yield, low intrinsic tritium retention, high melting point, and high thermal conductivity, W and W alloys are promising candidates for the divertor region in a magnetic fusion device. Transmutation reactions under neutron irradiation lead to the formation of He and H particles that potentially degrade material performance and might lead to failure. High He fluxes ultimately lead to the formation and bursting of bubbles that induce swelling, a strong decrease in toughness, and a nanoscale microstructure that potentially degrades the plasma. Understanding the behavior of He in polycrystalline W is thus of significant importance as one avenue for controlling the material properties under operating conditions. This paper studies the interaction of substitutional He atoms with various grain boundaries in pure W and the effect of the He presence on the system response to external loading. We observe that He segregates to all the interfaces tested and decreases the cohesion of the system at the grain boundary. Upon tension, the presence of He significantly decreases the yield stress, which depends considerably on the bubble pressure. Increasing pressure reduces cohesion, as expected. More complex stress states result in more convoluted behavior, with He hindering grain boundary sliding upon simple shear.
CONSTRAINTS ON THE PHYSICAL PROPERTIES OF MAIN BELT COMET P/2013 R3 FROM ITS BREAKUP EVENT
DOE Office of Scientific and Technical Information (OSTI.GOV)
Hirabayashi, Masatoshi; Sánchez, Diego Paul; Gabriel, Travis
2014-07-01
Jewitt et al. recently reported that main belt comet P/2013 R3 experienced a breakup, probably due to rotational disruption, with its components separating on mutually hyperbolic orbits. We propose a technique for constraining physical properties of the proto-body, especially the initial spin period and cohesive strength, as a function of the body's estimated size and density. The breakup conditions are developed by combining mutual orbit dynamics of the smaller components and the failure condition of the proto-body. Given a proto-body with a bulk density ranging from 1000 kg m{sup –3} to 1500 kg m{sup –3} (a typical range of the bulk density of C-type asteroids),more » we obtain possible values of the cohesive strength (40-210 Pa) and the initial spin state (0.48-1.9 hr). From this result, we conclude that although the proto-body could have been a rubble pile, it was likely spinning beyond its gravitational binding limit and would have needed cohesive strength to hold itself together. Additional observations of P/2013 R3 will enable stronger constraints on this event, and the present technique will be able to give more precise estimates of its internal structure.« less
Authentic leadership, group cohesion and group identification in security and emergency teams.
García-Guiu López, Carlos; Molero Alonso, Fernando; Moya Morales, Miguel; Moriano León, Juan Antonio
2015-01-01
Authentic leadership (AL) is a kind of leadership that inspires and promotes positive psychological capacities, underlining the moral and ethical component of behavior. The proposed investigation studies the relations among AL, cohesion, and group identification in security and emergency teams. A cross-sectional research design was conducted in which participated 221 members from 26 fire departments and operative teams from the local police of three Spanish provinces. The following questionnaires were administered: Authentic Leadership (ALQ), Group Cohesion (GEQ), and Mael and Ashford's Group Identification Questionnaire. A direct and positive relation was found between AL, cohesion, and group identification. An indirect relation was also found between AL and group cohesion through group identification, indicating the existence of partial mediation. The utility of the proposed model based on AL is considered; this model can be employed by those in charge of the fire departments and operative groups in organizations to improve workteams' cohesion. Both AL and group identification help to explain group cohesion in organizations committed to security and emergencies.
Rabinowitz, Jill A.; Osigwe, Ijeoma; Drabick, Deborah A.G.; Reynolds, Maureen D.
2016-01-01
Lower family cohesion is associated with adolescent internalizing and externalizing problems. However, there are likely individual differences in youth's responses to family processes. For example, adolescents higher in negative emotional reactivity, who often exhibit elevated physiological responsivity to context, may be differentially affected by family cohesion. We explored whether youth's negative emotional reactivity moderated the relation between family cohesion and youth's symptoms and tested whether findings were consistent with the diathesis-stress model or differential susceptibility hypothesis. Participants were 651 adolescents (M = 12.99 ± .95 years old; 72% male) assessed at two time points (Time 1, ages 12–14; Time 2, age 16) in Pittsburgh, PA. At Time 1, mothers reported on family cohesion and youth reported on their negative emotional reactivity. At Time 2, youth reported on their symptoms. Among youth higher in negative emotional reactivity, lower family cohesion predicted higher symptoms than higher family cohesion, consistent with the diathesis-stress model. PMID:27718379
Reitzel, Lorraine R; Kendzor, Darla E; Castro, Yessenia; Cao, Yumei; Businelle, Micheal S; Mazas, Carlos A; Cofta-Woerpel, Ludmila; Li, Yisheng; Cinciripini, Paul M; Ahluwalia, Jasjit S; Wetter, David W
2013-04-01
Social cohesion, the self-reported trust and connectedness between neighbors, may affect health behaviors via psychosocial mechanisms. Relations between individual perceptions of social cohesion and smoking cessation were examined among 397 Black treatment-seeking smokers. Continuation ratio logit models examined the relation of social cohesion and biochemically verified continuous smoking abstinence through 6 months post-quit. Indirect effects were examined in single mediator models using a nonparametric bootstrapping procedure. All analyses controlled for sociodemographics, tobacco dependence, and treatment. The total effect of social cohesion on continuous abstinence was non-significant (β = 0.05, p = 0.10). However, social cohesion was associated with social support, positive affect, negative affect, and stress, which, in turn, were each associated with abstinence in adjusted models (ps < 0.05). Results suggest that social cohesion may facilitate smoking cessation among Black smokers through desirable effects on psychosocial mechanisms that can result from living in a community with strong interpersonal connections.
Bromell, Lea; Cagney, Kathleen A
2014-03-01
This study investigated the impact of neighborhood social cohesion on the perceived companionship of nearly 1,500 community-dwelling older adults from the Neighborhood, Organization, Aging and Health project (NOAH), a Chicago-based study of older adult well-being in the neighborhood context. We hypothesized that the relationship between neighborhood-level social cohesion and individual residents' reports of companionship would be more pronounced among those who lived alone than those who resided with others. Controlling for age, gender, education, race, marital status, length of neighborhood residence, and self-rated health, neighborhood social cohesion predicted companionship among those who lived alone; for a one-unit increase in neighborhood social cohesion, the odds of reporting companionship increased by half. In contrast, social cohesion did not predict the companionship of those who resided with others. The results suggest that older adults who live alone particularly profit from the benefits of socially cohesive neighborhood environments. © The Author(s) 2013.
Reitzel, Lorraine R.; Kendzor, Darla E.; Castro, Yessenia; Cao, Yumei; Businelle, Micheal S.; Mazas, Carlos A.; Cofta-Woerpel, Ludmila; Li, Yisheng; Cinciripini, Paul M.; Ahluwalia, Jasjit S.; Wetter, David W.
2012-01-01
Background Social cohesion, the self-reported trust and connectedness between neighbors, may affect health behaviors via psychosocial mechanisms. Purpose Relations between individual perceptions of social cohesion and smoking cessation were examined among 397 Black treatment-seeking smokers. Methods Continuation ratio logit models examined the relation of social cohesion and biochemically-verified continuous smoking abstinence through 6 months post-quit. Indirect effects were examined in single mediator models using a nonparametric bootstrapping procedure. All analyses controlled for sociodemographics, tobacco dependence, and treatment. Results The total effect of social cohesion on continuous abstinence was non-significant (β=.05, p=.10). However, social cohesion was associated with social support, positive affect negative affect, and stress, which, in turn, were each associated with abstinence in adjusted models (ps<.05). Conclusions Results suggest that social cohesion may facilitate smoking cessation among Black smokers through desirable effects on psychosocial mechanisms that can result from living in a community with strong interpersonal connections. PMID:23135831
Sze, Tat-Ming; Hsieh, Pei-Jung; Lin, Sieh-Hwa; Chen, I-Jung
2013-08-01
This study investigates the progression of family cohesion perceptions and depressive symptoms during the character development stage in adolescents. Data were used from the Taiwan Youth Project. The final sample comprised 2,690 adolescents with 1,312 girls (48.8%; M age = 13.0 yr., SD = 0.5). Latent curve growth analysis was employed to explore these developments. Seventh-grade girls reported greater family cohesion and more depressive symptoms than boys, and boys reported greater growth in family cohesion than girls. However, progression of depressive symptoms was not associated with the child's sex. Higher perceived family cohesion in Grade 7 correlated with less increase of depressive symptoms from Grades 9 to 11. The long-term positive influence of family cohesion on depressive symptoms is discussed.
Filipovic, M; Lukic, M; Djordjevic, S; Krstonosic, V; Pantelic, I; Vuleta, G; Savic, S
2017-10-01
Consumers' demand for improved products' performance, alongside with the obligation of meeting the safety and efficacy goals, presents a key reason for the reformulation, as well as a challenging task for formulators. Any change of the formulation, whether it is wanted - in order to innovate the product (new actives and raw materials) or necessary - due to, for example legislative changes (restriction of ingredients), ingredients market unavailability, new manufacturing equipment, may have a number of consequences, desired or otherwise. The aim of the study was to evaluate the influence of multiple factors - variations of the composition, manufacturing conditions and their interactions, on emulsion textural and rheological characteristics, applying the general experimental factorial design and, subsequently, to establish the approach that could replace, to some extent, certain expensive and time-consuming tests (e.g. certain sensory analysis), often required, partly or completely, after the reformulation. An experimental design strategy was utilized to reveal the influence of reformulation factors (addition of new actives, preparation method change) on textural and rheological properties of cosmetic emulsions, especially those linked to certain sensorial attributes, and droplet size. The general experimental factorial design revealed a significant direct effect of each factor, as well as their interaction effects, on certain characteristics of the system and provided some valuable information necessary for fine-tuning reformulation conditions. Upon addition of STEM-liposomes, consistency, index of viscosity, firmness and cohesiveness were decreased, as along with certain rheology parameters (elastic and viscous modulus), whereas maximal and minimal apparent viscosities and droplet size were increased. The presence of an emollient (squalene) affected all the investigated parameters in a concentration-dependent manner. Modification of the preparation method (using Ultra Turrax instead of a propeller stirrer) produced emulsions with higher firmness and maximal apparent viscosity, but led to a decrease in minimal apparent viscosity, hysteresis loop area, all monitored parameters of oscillatory rheology and droplet size. The study showed that the established approach which combines a general experimental design and instrumental, rheological and textural measurements could be appropriate, more objective, repeatable and time and money-saving step towards developing cosmetic emulsions with satisfying, improved or unchanged, consumer-acceptable performance during the reformulation. © 2017 Society of Cosmetic Scientists and the Société Française de Cosmétologie.
NASA Astrophysics Data System (ADS)
Manning, A. J.; Schoellhamer, D. H.; Mehta, A. J.; Schladow, G.; Monismith, S. G.; Huang, I. B.; Kuwabara, J. S.; Carter, J. L.; Sheremet, A.; Parsons, D. R.; Whitehouse, R. J. S.; Todd, D.; Benson, T.; Spearman, J.
2016-12-01
Many coastal and inland waterways are dominated by muddy sediments; typically a mixture of clay minerals and various types of organic matter. When cohesive sediment is entrained into suspension, the particles tend to flocculate. Flocs are less dense, but faster settling than their constituent particles thus affecting their depositional characteristics. As flocs grow, their effective densities generally decrease, but their settling rates rise due to the Stokes' Law relationship. Flocculation effects become even more complex when purely cohesive sediments are mixed with different ratios of non-cohesive sediments, and if biological activity (e.g., exudate production) affects the resultant cohesion. Developing instrumentation that can provide key physical and dynamical data on depositional rates of flocculating sediments is extremely important in advancing our understanding of natural flocculation processes. Complementary qualitative and quantitative data improve our understanding of the depositional and aggregational physical processes through parameterization. This presentation will demonstrate recent advances in the study of the flocculation process through the use of video image technology. One such device pioneered at HR Wallingford, and implemented with co-authors, is the high-resolution floc video camera, LabSFLOC - Laboratory Spectral Flocculation Characteristics (developed by Prof. Manning). LabSFLOC can observe (directly or indirectly) floc spectral physical properties, including: floc size, settling velocity, effective density, porosity, shape, mass, and settling flux (using controlled volume referencing). These data are highly desirable for sediment transport modelers. Examples of floc measurements from locations in estuaries, tidal lagoons, river deltas, and lakes from locations across the US will be presented. In addition, we will demonstrate how video floc data can be used to parameterize floc settling characteristics for use in modeling.
ERIC Educational Resources Information Center
Gasparinatou, Alexandra; Grigoriadou, Maria
2013-01-01
In this study, we examine the effect of background knowledge and local cohesion on learning from texts. The study is based on construction-integration model. Participants were 176 undergraduate students who read a Computer Science text. Half of the participants read a text of maximum local cohesion and the other a text of minimum local cohesion.…
Cohesion: The Vital Ingredient for Successful Army Units
1982-04-19
responding in military life as well. A special problem of social cohesion directly related to social background was the integration of minority troops...forces has been a powerful verification of sociological theory concerning social cohesion and organizational effectiveness. Sociological theory does not...prevent the development of groups with social cohesion committed to the military hierarchy. 2 5 Personality of Wnit Mmbers Among the characteristics
Kingsbury, M; Kirkbride, J B; McMartin, S E; Wickham, M E; Weeks, M; Colman, I
2015-11-01
The objective of this study was to examine associations between trajectories of childhood neighbourhood social cohesion and adolescent mental health and behaviour. This study used data from the National Longitudinal Survey of Children and Youth, a nationally representative sample of Canadian children. The sample included 5577 children aged 0-3 years in 1994-1995, prospectively followed until age 12-15 years. Parental perceived neighbourhood cohesion was assessed every 2 years. Latent growth class modelling was used to identify trajectories of neighbourhood cohesion. Mental health and behavioural outcomes were self-reported at age 12-15 years. Logistic regression was used to examine associations between neighbourhood cohesion trajectories and outcomes, adjusting for potential confounders. Five distinct trajectories were identified: 'stable low' (4.2%); 'moderate increasing' (9.1%); 'stable moderate' (68.5%); 'high falling' (8.9%); and 'stable high' (9.3%). Relative to those living in stable moderately cohesive neighbourhoods, those in stable low cohesive neighbourhoods were more likely to experience symptoms of anxiety/depression [odds ratio (OR) = 1.73, 95% confidence interval (CI) 1.04-2.90] and engage in indirect aggression (OR = 1.62, 95% CI 1.07-2.45). Those with improvements in neighbourhood cohesion had significantly lower odds of hyperactivity (OR = 0.67, 95% CI 0.46-0.98) and indirect aggression (OR = 0.69, 95% CI 0.49-0.96). In contrast, those with a decline in neighbourhood cohesion had increased odds of hyperactivity (OR = 1.67, 95% CI 1.21-2.29). Those in highly cohesive neighbourhoods in early childhood were more likely to engage in prosocial behaviour ('high falling': OR = 1.93, 95% CI 1.38-2.69; 'stable high': OR = 1.89, 95% CI 1.35-2.63). These results suggest that neighbourhood cohesion in childhood may have time-sensitive effects on several domains of adolescent mental health and behaviour.
Kingsbury, Mila; Kirkbride, James B; McMartin, Seanna E; Wickham, Maeve E; Weeks, Murray; Colman, Ian
2017-01-01
Background The objective of this study was to examine associations between trajectories of childhood neighbourhood social cohesion and adolescent mental health and behaviour. Methods This study used data from the National Longitudinal Survey of Children and Youth, a nationally representative sample of Canadian children. The sample included 5577 children aged 0-3 in 1994/95, prospectively followed until age 12-15. Parental perceived neighbourhood cohesion was assessed every two years. Latent growth class modeling was used to identify trajectories of neighbourhood cohesion. Mental health and behavioural outcomes were self-reported at age 12-15 years. Logistic regression was used to examine associations between neighbourhood cohesion trajectories and outcomes, adjusting for potential confounders. Results Five distinct trajectories were identified: ‘stable low’ (4.2%); ‘moderate increasing’ (9.1%); ‘stable moderate’ (68.5%); ‘high falling’ (8.9%); and, ‘stable high’ (9.3%). Relative to those living in stable moderately cohesive neighbourhoods, those in stable low cohesive neighbourhoods were more likely to experience symptoms of anxiety/depression (OR=1.75; 95%CI: 1.05,2.92) and engage in indirect aggression (OR=1.59; 95%CI: 1.05,2.40). Those with improvements in neighbourhood cohesion had significantly lower odds of hyperactivity (OR=0.68; 95%CI: 0.46,0.99) and indirect aggression (OR=0.68; 95%CI: 0.49,0.95). In contrast, those with a decline in neighbourhood cohesion had increased odds of hyperactivity (OR=1.65; 95%CI: 1.20,2.27). Those in highly cohesive neighbourhoods in early childhood were more likely to engage in prosocial behaviour (‘high falling’: OR=1.95; 95%CI: 1.40,2.72; ‘stable high’: OR=1.91; 95%CI: 1.37,2.66). Conclusions These results suggest that neighbourhood cohesion in childhood may have time-sensitive effects on several domains of adolescent mental health and behaviour. PMID:26169730
Differences by Sexual Orientation in Perceptions of Neighborhood Cohesion: Implications for Health.
Henning-Smith, Carrie; Gonzales, Gilbert
2018-06-01
A large body of research documents the relationship between health and place, including the positive association between neighborhood cohesion and health. However, very little research has examined neighborhood cohesion by sexual orientation. This paper addresses that gap by examining differences in perceived neighborhood cohesion by sexual orientation. We use data from the 2016 National Health Interview Survey (n = 28,164 respondents aged 18 years and older) to examine bivariate differences by sexual orientation in four measures of neighborhood cohesion. We then use ordered logistic regression models to assess the relationship between sexual orientation and a scaled measure of neighborhood cohesion, adjusting for socio-demographic characteristics, living arrangements, health status, region, and neighborhood tenure. We find that lesbian, gay, and bisexual (LGB) adults are less likely to say that they live in a close-knit neighborhood (54.6 vs. 65.6%, p < 0.001), they can count on their neighbors (74.7 vs. 83.1%, p < 0.001), they trust their neighbors (75.5 vs. 83.7%, p < 0.001), or people in their neighborhood help each other out (72.9 vs. 83.1%, p < 0.001), compared to heterosexual adults. Even after controlling for socio-demographic factors, neighborhood cohesion scores are lower for LGB adults compared to heterosexual adults (odds ratio of better perceived neighborhood cohesion for sexual minorities: 0.70, p < 0.001). Overall, LGB adults report worse neighborhood cohesion across multiple measures, even after adjusting for individual characteristics and neighborhood tenure. Because living in a cohesive neighborhood is associated with better health outcomes, future research, community-level initiatives, and public policy efforts should focus on creating welcoming neighborhood environments for sexual minorities.
The Impact of Electronic Health Records and Teamwork on Diabetes Care Quality
Graetz, Ilana; Huang, Jie; Brand, Richard; Shortell, Stephen M.; Rundall, Thomas G.; Bellows, Jim; Hsu, John; Jaffe, Marc; Reed, Mary E.
2016-01-01
Objective Evidence of the impact Electronic Health Records (EHR) on clinical outcomes remains mixed. The impact EHRs likely depends on the organizational context in which they are used. We focus on one aspect of the organizational context: cohesion of primary care teams. We examined whether team cohesion among primary care team members changed the association of EHR use and changes in clinical outcomes for patients with diabetes. Study Design We combined provider-reported primary care team cohesion with lab values for patients with diabetes collected during the staggered EHR implementation (2005–2009). We used multivariate regression models with patient-level fixed effects to assess whether team cohesion levels changed the association between outpatient EHR use and clinical outcomes for patients with diabetes. Subjects 80,611 patients with diabetes mellitus. Measures Changes in hemoglobin A1c (HbA1c) and low-density lipoprotein cholesterol (LDL-C) Results For HbA1c, EHR use was associated with an average decrease of 0.11% for patients with higher cohesion primary care teams compared with a decrease of 0.08% for patients with lower cohesion teams (difference 0.02% in HbA1c, 95%CI: 0.01–0.03). For LDL-C, EHR use was associated with a decrease of 2.15 mg/dL for patients with higher cohesion primary teams compared with a decrease of 1.42 mg/dL for patients with lower cohesion teams (difference 0.73 mg/dL, 95%CI: 0.41–1.11 mg/dL). Conclusions Patients cared for by higher cohesion primary care teams experienced modest but statistically significantly greater EHR-related health outcome improvements, compared with patients cared for by providers practicing in lower cohesion teams. PMID:26671699
Unit cohesion, traumatic exposure and mental health of military personnel.
Kanesarajah, J; Waller, M; Zheng, W Y; Dobson, A J
2016-06-01
The benefit of military unit cohesion to morale and psychological resilience is well established. But it remains unclear whether unit cohesion modifies the association between deployment-related traumatic exposure and mental health problems. To examine the association between unit cohesion, traumatic exposure and poor mental health [symptoms of post-traumatic stress disorder (PTSD), psychological distress and alcohol dependency] and assess whether the relationship between traumatic exposure and poor mental health differs by level of unit cohesion. A self-reported cross-sectional survey of Australian military personnel deployed to Iraq or Afghanistan between 2001 and 2009. Among 11411 participants, those with low levels of unit cohesion had higher odds of PTSD symptoms [aOR (95% CI): 2.54 (1.88, 3.42)], very high psychological distress [aOR (95% CI): 4.28 (3.04, 6.02)] and a high level of alcohol problems [aOR (95% CI): 1.71 (1.32, 2.22)] compared with those reporting high unit cohesion on deployment. Higher exposure to traumatic events on deployment was associated with greater risk of PTSD symptoms, very high levels of psychological distress and high levels of alcohol problems in this cohort. However, there was no evidence of a statistically significant interaction between unit cohesion and traumatic exposures in influencing poor mental health. Our findings suggest that both unit cohesion and traumatic exposure are independently associated with poor mental health. Efforts to improve military unit cohesion may help to improve the mental health resilience of military personnel, regardless of their level of traumatic exposure. © The Author 2016. Published by Oxford University Press on behalf of the Society of Occupational Medicine. All rights reserved. For Permissions, please email: journals.permissions@oup.com.
The Impact of Thermocycling Process on the Dislodgement Force of Different Endodontic Cements
Saghiri, Mohammad Ali; Asatourian, Armen; Garcia-Godoy, Franklin; Gutmann, James L.; Sheibani, Nader
2013-01-01
To evaluate the effects of thermocycling (500 cycles, 5°C/55°C) on the push-out bond strength of calcium silicate based cements including WMTA, Nano-WMTA, and Bioaggregate to root dentin. Forty-eight dentin slices were prepared and divided into 3 groups (n = 16) and filled with Angelus WMTA, Nano-WMTA, or Bioaggregate. After incubation, half of the samples were thermocycled while the other half remained untreated. Push-out bond strength was calculated, and the modes of the bond failures were determined by SEM. The highest bond strength was seen in nonthermocycled Nano-WMTA samples and the lowest in thermocycled Bioaggregate samples. The significant differences between nonthermocycled and thermocycled samples were only noticed in WMTA and Nano-WMTA groups (P < 0.001). The mode of failure for thermocycled samples of all three cements was mostly cohesive. Thermocycling process can drastically affect the push-out bond strength of calcium silicate based cements. The intrastructural damages occurred due to the thermal stresses, causing cohesive failures in set materials. Sealing property of endodontic cements which have experienced the thermal stresses can be jeopardized due to occlusal forces happening in furcation cites. PMID:24063004
NASA Astrophysics Data System (ADS)
Ye, Leiping; Parsons, Daniel; Manning, Andrew
2016-04-01
There remains a lack of process-based knowledge of sediment dynamics within flows over bedforms generated in complex mixtures of cohesionless sand and biologically-active cohesive muds in natural estuarine flow systems. The work to be presented forms a part of the UK NERC "COHesive BEDforms (COHBED)" project which aims to fill this gap in knowledge. Herein results from a field survey in sub-tidal zone of Dee estuary (NW, England) and a set of large-scale laboratory experiments, conducted using mixtures of non-cohesive sands, cohesive muds and Xanthan gum (as a proxy for the biological stickiness of Extracellular Polymeric Substances (EPS)) will be presented. The results indicate the significance of biological-active cohesive sediments in controlling winnowing rates and flocculation dynamics, which contributes significantly to rates of bedform evolution.
Young, Marielle C; Gerber, Monica W; Ash, Tayla; Horan, Christine M; Taveras, Elsie M
2018-05-16
Native Hawaiians and Pacific Islanders (NHPIs) have the lowest attainment of healthy sleep duration among all racial and ethnic groups in the United States. We examined associations of neighborhood social cohesion with sleep duration and quality. Cross-sectional analysis of 2,464 adults in the NHPI National Health Interview Survey (2014). Neighborhood social cohesion was categorized as a continuous and categorical variable into low (<12), medium (12-14) and high (>15) according to tertiles of the distribution of responses. We used multinomial logistic regression to examine the adjusted odds ratio of short and long sleep duration relative to intermediate sleep duration. We used binary logistic regression for dichotomous sleep quality outcomes. Sleep outcomes were modeled as categorical variables. 40% of the cohort reported short (<7 hours) sleep duration and only 4% reported long (>9 hours) duration. Mean (SE, range) social cohesion score was 12.4 units (0.11, 4-16) and 23% reported low social cohesion. In multivariable models, each 1 SD decrease in neighborhood social cohesion score was associated with higher odds of short sleep duration (OR: 1.14, 95% CI: 1.02, 1.29). Additionally, low social cohesion was associated with increased odds of short sleep duration (OR: 1.53, 95% CI: 1.10, 2.13). No associations between neighborhood social cohesion and having trouble falling or staying asleep and feeling well rested were found. Low neighborhood social cohesion is associated with short sleep duration in NHPIs.
The Analysis of Soil Resistance During Screw Displacement Pile Installation
NASA Astrophysics Data System (ADS)
Krasinski, Adam
2015-02-01
The application of screw displacement piles (SDP) is still increasing due to their high efficiency and many advantages. However, one technological problem is a serious disadvantage of those piles. It relates to the generation of very high soil resistance during screw auger penetration, especially when piles are installed in non-cohesive soils. In many situations this problem causes difficulties in creating piles of designed length and diameter. It is necessary to find a proper method for prediction of soil resistance during screw pile installation. The analysis of screw resistances based on model and field tests is presented in the paper. The investigations were carried out as part of research project, financed by the Polish Ministry of Science and Higher Education. As a result of tests and analyses the empirical method for prediction of rotation resistance (torque) during screw auger penetration in non-cohesive subsoil based on CPT is proposed.
Schoellhamer, D.H.; Ganju, N.K.; Mineart, P.R.; Lionberger, M.A.; Kusuda, T.; Yamanishi, H.; Spearman, J.; Gailani, J. Z.
2008-01-01
Bathymetric change in tidal environments is modulated by watershed sediment yield, hydrodynamic processes, benthic composition, and anthropogenic activities. These multiple forcings combine to complicate simple prediction of bathymetric change; therefore, numerical models are necessary to simulate sediment transport. Errors arise from these simulations, due to inaccurate initial conditions and model parameters. We investigated the response of bathymetric change to initial conditions and model parameters with a simplified zero-dimensional cohesive sediment transport model, a two-dimensional hydrodynamic/sediment transport model, and a tidally averaged box model. The zero-dimensional model consists of a well-mixed control volume subjected to a semidiurnal tide, with a cohesive sediment bed. Typical cohesive sediment parameters were utilized for both the bed and suspended sediment. The model was run until equilibrium in terms of bathymetric change was reached, where equilibrium is defined as less than the rate of sea level rise in San Francisco Bay (2.17 mm/year). Using this state as the initial condition, model parameters were perturbed 10% to favor deposition, and the model was resumed. Perturbed parameters included, but were not limited to, maximum tidal current, erosion rate constant, and critical shear stress for erosion. Bathymetric change was most sensitive to maximum tidal current, with a 10% perturbation resulting in an additional 1.4 m of deposition over 10 years. Re-establishing equilibrium in this model required 14 years. The next most sensitive parameter was the critical shear stress for erosion; when increased 10%, an additional 0.56 m of sediment was deposited and 13 years were required to re-establish equilibrium. The two-dimensional hydrodynamic/sediment transport model was calibrated to suspended-sediment concentration, and despite robust solution of hydrodynamic conditions it was unable to accurately hindcast bathymetric change. The tidally averaged box model was calibrated to bathymetric change data and shows rapidly evolving bathymetry in the first 10-20 years, though sediment supply and hydrodynamic forcing did not vary greatly. This initial burst of bathymetric change is believed to be model adjustment to initial conditions, and suggests a spin-up time of greater than 10 years. These three diverse modeling approaches reinforce the sensitivity of cohesive sediment transport models to initial conditions and model parameters, and highlight the importance of appropriate calibration data. Adequate spin-up time of the order of years is required to initialize models, otherwise the solution will contain bathymetric change that is not due to environmental forcings, but rather improper specification of initial conditions and model parameters. Temporally intensive bathymetric change data can assist in determining initial conditions and parameters, provided they are available. Computational effort may be reduced by selectively updating hydrodynamics and bathymetry, thereby allowing time for spin-up periods. reserved.
NASA Astrophysics Data System (ADS)
Pollen, N.; Simon, A.
2006-12-01
Research on the interactions between vegetation and channel flow dynamics has shown that vegetation is an important control on river morphology and planform. Increased vegetation density is commonly linked to a decrease in bank erosion and lateral migration rates. Roots add to bank strength through the production of a reinforced soil-root matrix, and vegetation can also act to increase bank stability through its hydrological effects, including canopy interception, and removal of soil water through evapotranspiration. Flow dynamics are also affected by vegetation, with a number of studies showing a linkage between vegetation density and width- depth-velocity relations and bank roughness. To evaluate the effects of vegetation on channel morphology and planform, several experimental studies in flumes have used alfalfa sprouts (Medicago sativa) to seed the bed and banks of experimental channels. In such studies, the effects of vegetation are accounted for by qualitatively increasing the resistance of the bank material to lateral erosion. However, the material properties of alfalfa roots and stems, and the actual increase in resistance provided to the banks under different densities of alfalfa have thus far been ignored. To quantify this added erosion resistance, alfalfa sprouts were grown for 7 to 21 days, in sand with a d50 of 0.23 mm. At regular intervals, roots and stems were tested to measure tensile strength and forces required for pullout. Results of the tensile-strength measurements display the typical non-linear decrease of tensile strength (in MPa) with increasing root diameter but the curve is shifted to the left (weaker for a given diameter) of other riparian species. However, to calculate the increase in bank cohesion due to alfalfa roots, it is necessary to also account for the number of roots, and the distribution of different root diameters. The number of roots was calculated for a range of stem densities (0 to 10 stems/cm2), assuming a single, un-branching root per stem. Values for the additional cohesion provided by the alfalfa roots were calculated using the root- reinforcement model, RipRoot, producing values of 0 to 11.8 kPa. These results provide a means of quantifying the additional bank resistance provided to experimental channels under different stem/root densities. Cohesion values obtained in this way were successfully related to studies of braiding intensity published by others. The geometric properties of alfalfa scale up from experiments in flumes to approximate young trees on a floodplain. However, soil properties such as cohesion cannot be scaled. As such, the cohesion values due to roots calculated here represent the actual magnitude of reinforcement provided, rather than a scaled value.
2001-12-15
emotional stability, openness to experience, agreeableness, learning and performance goal orientation) and process variables ( social cohesion and group...both subjective performance measures and 6 of the 7 objective performance measures over that of social cohesion . Social cohesion predicted unique...variance in team member satisfaction over that of group potency. Additionally, social cohesion mediated the relationship between agreeableness and team
Formal and Informal Work Group Relationships With Performance: A Moderation Model Using Social
2006-03-01
networks can be divided into two main categories: formal and informal (Scott, 2000). Similar distinctions have been made between task and social cohesion (Mullen...Cooper, 1994; Carron, Widmeyer, & Brawley, 1985; Zaccaro & Lowe, 1986; Zaccaro & McCoy, 1988). Social cohesion has been defined as...performance and social cohesion and performance (Beal et al., 2003). This move toward a multidimensional view of cohesion is consistent with the
Perez, Lilian G; Arredondo, Elva M; McKenzie, Thomas L; Holguin, Margarita; Elder, John P; Ayala, Guadalupe X
2015-10-01
Greater neighborhood social cohesion is linked to fewer depressive symptoms and greater physical activity, but the role of physical activity on the relationship between neighborhood social cohesion and depression is poorly understood. The purpose of the study was to examine the effects of physical activity on the association between neighborhood social cohesion and depressive symptoms. Multivariate logistic regression tested the moderation of self-reported leisure-time moderate-to-vigorous physical activity (LTMVPA) and active use of parks or recreational facilities on the association between neighborhood social cohesion and depressive symptoms among 295 randomly selected Latino adults who completed a face-to-face interview. After adjusting for age, gender, and income, neighborhood social cohesion and depressive symptoms were inversely related (OR = 0.8; 95% CI: 0.5-1.2). Active use of parks or recreational facilities moderated the association between neighborhood social cohesion and depressive symptoms but meeting the recommendations for LTMVPA did not. Latinos who reported active use of parks or recreational facilities and higher levels of neighborhood social cohesion had fewer depressive symptoms than peers who did not use these spaces. Future studies are needed to test strategies for promoting active use of parks or recreational facilities to address depression in Latinos.
Group cohesion and social support of the nurses in a special unit and a general unit in Korea.
Ko, Yu Kyung
2011-07-01
To identify the degree of group cohesion and social support of nurses in special and general units in hospitals in Korea, and to compare group cohesion and social support between the two groups. The level of commitment nurses have to their organizations has been shown to correlate with work group cohesion and social support. The participants were 1751 nurses who were working in Korean hospitals. Data were collected using a structured questionnaire and were analysed using SAS. The statistical methods included: descriptive statistics, t-test, anova and Pearson's correlation coefficients. Group cohesion of nurses on special wards was significantly higher than for nurses on general wards. No significant difference was found between types of units in terms of social support. The degree of group cohesion was significantly different in terms of the respondents' clinical experience, position, religion, job satisfaction, number of supportive superiors and number of supportive peers. A statistically significant correlation was found between group cohesion scores and degree of social support. Hospital management can accomplish their goals more effectively through knowledge of the level of group cohesion, superior support and peer support for nursing staff in accordance with unit specialty. © 2011 The Author. Journal compilation © 2011 Blackwell Publishing Ltd.
The association between EHRs and care coordination varies by team cohesion.
Graetz, Ilana; Reed, Mary; Shortell, Stephen M; Rundall, Thomas G; Bellows, Jim; Hsu, John
2014-02-01
To examine whether primary care team cohesion changes the association between using an integrated outpatient-inpatient electronic health record (EHR) and clinician-rated care coordination across delivery sites. Self-administered surveys of primary care clinicians in a large integrated delivery system, collected in 2005 (N=565), 2006 (N=678), and 2008 (N=626) during the staggered implementation of an integrated EHR (2005-2010), including validated questions on team cohesion. Using multivariable regression, we examined the combined effect of EHR use and team cohesion on three dimensions of care coordination across delivery sites: access to timely and complete information, treatment agreement, and responsibility agreement. Among clinicians working in teams with higher cohesion, EHR use was associated with significant improvements in reported access to timely and complete information (53.5 percent with EHR vs. 37.6 percent without integrated-EHR), agreement on treatment goals (64.3 percent vs. 50.6 percent), and agreement on responsibilities (63.9 percent vs. 55.2 percent, all p<.05). We found no statistically significant association between use of the integrated-EHR and reported care coordination in less cohesive teams. The association between EHR use and reported care coordination varied by level of team cohesion. EHRs may not improve care coordination in less cohesive teams. © Health Research and Educational Trust.
Jones, Norman; Campion, Ben; Keeling, Mary; Greenberg, Neil
2018-02-01
Military research suggests a significant association between leadership, cohesion, mental health stigmatisation and perceived barriers to care (stigma/BTC). Most studies are cross sectional, therefore longitudinal data were used to examine the association of leadership and cohesion with stigma/BTC. Military personnel provided measures of leadership, cohesion, stigma/BTC, mental health awareness and willingness to discuss mental health following deployment (n = 2510) and 4-6 months later (n = 1636). At follow-up, baseline leadership and cohesion were significantly associated with stigma/BTC; baseline cohesion alone was significantly associated with awareness of and willingness to discuss mental health at follow-up. Over time, changes in perceived leadership and cohesion were significantly associated with corresponding changes in stigma/BTC levels. Stigma/BTC content was similar in both surveys; fear of being viewed as weak and being treated differently by leaders was most frequently endorsed while thinking less of a help-seeking team member and unawareness of potential help sources were least common. Effective leadership and cohesion building may help to reduce stigma/BTC in military personnel. Mental health awareness and promoting the discussion of mental health matters may represent core elements of supportive leader behaviour. Perceptions of weakness and fears of being treated differently represent a focus for stigma/BTC reduction.
Elbe, Anne-Marie; Wikman, Johan Michael; Zheng, Miky; Larsen, Malte Nejst; Nielsen, Glen; Krustrup, Peter
2017-04-01
This study investigates the enjoyment and cohesion of school children participating in a school-based high-intensity physical activity (PA) intervention. Both enjoyment and cohesion have been found to be important factors for adherence to regular physical and sport activity, an important outcome of PA interventions. The sample consisted of 300 pupils (mean age: 9.3 years; 52.7% female) assigned to a team sport intervention, an individual sport intervention, or a control group for 10 months. The Physical Activity Enjoyment Scale and Youth Sport Environment Questionnaire were used to measure enjoyment and cohesion. The Yo-Yo IR1C test determined fitness improvements. Results showed that enjoyment and cohesion (social) measured at the beginning of the intervention significantly predict fitness improvements achieved after 10 months. No differing developmental effects over time could be found in the intervention groups with regard to cohesion and enjoyment when comparing them to the control group. However, enjoyment and cohesion (social) significantly decreased in the groups that performed individual sports. Team sports seem to be more advantageous for the development of enjoyment and cohesion, which are both factors that positively impact the health outcomes of the intervention.
Perez, Lilian G.; Arredondo, Elva M.; McKenzie, Thomas L.; Holguin, Margarita; Elder, John P.; Ayala, Guadalupe X.
2017-01-01
Background Greater neighborhood social cohesion is linked to fewer depressive symptoms and greater physical activity, but the role of physical activity on the relationship between neighborhood social cohesion and depression is poorly understood. The purpose of the study was to examine the effects of physical activity on the association between neighborhood social cohesion and depressive symptoms. Methods Multivariate logistic regression tested the moderation of self-reported leisure time moderate-to vigorous-physical activity (LTMVPA) and active use of parks or recreational facilities on the association between neighborhood social cohesion and depressive symptoms among 295 randomly selected Latino adults who completed a face-to-face interview. Results After adjusting for age, gender, and income, neighborhood social cohesion and depressive symptoms were inversely related (OR=0.8; 95% CI: 0.5–1.2). Active use of parks or recreational facilities moderated the association between neighborhood social cohesion and depressive symptoms but meeting the recommendations for LTMVPA did not. Latinos who reported active use of parks or recreational facilities and higher levels of neighborhood social cohesion had fewer depressive symptoms than peers who did not use these spaces. Conclusions Future studies are needed to test strategies for promoting active use of parks or recreational facilities to address depression in Latinos. PMID:25599244
Mind the gap! Automated concept map feedback supports students in writing cohesive explanations.
Lachner, Andreas; Burkhart, Christian; Nückles, Matthias
2017-03-01
Many students are challenged with the demand of writing cohesive explanations. To support students in writing cohesive explanations, we developed a computer-based feedback tool that visualizes cohesion deficits of students' explanations in a concept map. We conducted three studies to investigate the effectiveness of such feedback as well as the underlying cognitive processes. In Study 1, we found that the concept map helped students identify potential cohesion gaps in their drafts and plan remedial revisions. In Study 2, students with concept map feedback conducted revisions that resulted in more locally and globally cohesive, and also more comprehensible, explanations than the explanations of students who revised without concept map feedback. In Study 3, we replicated the findings of Study 2 by and large. More importantly, students who had received concept map feedback on a training explanation 1 week later wrote a transfer explanation without feedback that was more cohesive than the explanation of students who had received no feedback on their training explanation. The automated concept map feedback appears to particularly support the evaluation phase of the revision process. Furthermore, the feedback enabled novice writers to acquire sustainable skills in writing cohesive explanations. (PsycINFO Database Record (c) 2017 APA, all rights reserved).
Petrovic, Igor; Hip, Ivan; Fredlund, Murray D
2016-09-01
The variability of untreated municipal solid waste (MSW) shear strength parameters, namely cohesion and shear friction angle, with respect to waste stability problems, is of primary concern due to the strong heterogeneity of MSW. A large number of municipal solid waste (MSW) shear strength parameters (friction angle and cohesion) were collected from published literature and analyzed. The basic statistical analysis has shown that the central tendency of both shear strength parameters fits reasonably well within the ranges of recommended values proposed by different authors. In addition, it was established that the correlation between shear friction angle and cohesion is not strong but it still remained significant. Through use of a distribution fitting method it was found that the shear friction angle could be adjusted to a normal probability density function while cohesion follows the log-normal density function. The continuous normal-lognormal bivariate density function was therefore selected as an adequate model to ascertain rational boundary values ("confidence interval") for MSW shear strength parameters. It was concluded that a curve with a 70% confidence level generates a "confidence interval" within the reasonable limits. With respect to the decomposition stage of the waste material, three different ranges of appropriate shear strength parameters were indicated. Defined parameters were then used as input parameters for an Alternative Point Estimated Method (APEM) stability analysis on a real case scenario of the Jakusevec landfill. The Jakusevec landfill is the disposal site of the capital of Croatia - Zagreb. The analysis shows that in the case of a dry landfill the most significant factor influencing the safety factor was the shear friction angle of old, decomposed waste material, while in the case of a landfill with significant leachate level the most significant factor influencing the safety factor was the cohesion of old, decomposed waste material. The analysis also showed that a satisfactory level of performance with a small probability of failure was produced for the standard practice design of waste landfills as well as an analysis scenario immediately after the landfill closure. Copyright © 2015 Elsevier Ltd. All rights reserved.
Are diverse societies less cohesive? Testing contact and mediated contact theories.
McKenna, Sarah; Lee, Eunro; Klik, Kathleen A; Markus, Andrew; Hewstone, Miles; Reynolds, Katherine J
2018-01-01
Previous research has demonstrated that there is a negative relationship between ethnic diversity in a local community and social cohesion. Often the way social cohesion is assessed, though, varies across studies and only some aspects of the construct are included (e.g., trust). The current research explores the relationship between diversity and social cohesion across a number of indicators of social cohesion including neighbourhood social capital, safety, belonging, generalized trust, and volunteering. Furthermore, social psychological theories concerning the role of positive contact and its impact on feelings of threat are investigated. Using a sample of 1070 third generation 'majority' Australians and structural equation modelling (SEM), findings suggest ethnic diversity is related to positive intergroup contact, and that contact showed beneficial impacts for some indicators of social cohesion both directly and indirectly through reducing perceived threat. When interethnic contact and perceived threat are included in the model there is no direct negative effect between diversity and social cohesion. The theoretical implications of these findings are outlined including the importance of facilitating opportunities for positive contact in diverse communities.
Perceived Social Cohesion, Frequency of Going Out, and Depressive Symptoms in Older Adults
Choi, Namkee G.; Kim, Jinseok; DiNitto, Diana M.; Marti, C. Nathan
2015-01-01
Objective: To examine both cross-sectional and longitudinal relationships between older adults’ perceptions of social cohesion in their community and depressive symptoms and the potential mediating effect of the frequency of going outside one’s home/building. Method: Using two waves (T1 and T2) of the National Health and Aging Trend Study (n = 5,326), gender-stratified structural equation models were estimated to determine direct and indirect effects of perceived social cohesion on depressive symptoms. Results: At T1, both perceived cohesion and frequency of going out were directly associated with depressive symptoms; however, perceived cohesion predicted frequency of going out only for women. At T2, only frequency of going out was directly associated with depressive symptoms, although perceived cohesion predicted frequency of going out for both genders. T1 perceived cohesion did not predict T2 depressive symptoms. T1 depressive symptoms were the strongest predictor of T2 depressive symptoms. Conclusion: The findings underscore the importance of enhancing the social environment in promoting mental health in late life through active aging. PMID:28138478
Choi, Namkee G; Kim, Jinseok; DiNitto, Diana M; Marti, C Nathan
2015-01-01
Objective: To examine both cross-sectional and longitudinal relationships between older adults' perceptions of social cohesion in their community and depressive symptoms and the potential mediating effect of the frequency of going outside one's home/building. Method: Using two waves (T1 and T2) of the National Health and Aging Trend Study ( n = 5,326), gender-stratified structural equation models were estimated to determine direct and indirect effects of perceived social cohesion on depressive symptoms. Results: At T1, both perceived cohesion and frequency of going out were directly associated with depressive symptoms; however, perceived cohesion predicted frequency of going out only for women. At T2, only frequency of going out was directly associated with depressive symptoms, although perceived cohesion predicted frequency of going out for both genders. T1 perceived cohesion did not predict T2 depressive symptoms. T1 depressive symptoms were the strongest predictor of T2 depressive symptoms. Conclusion: The findings underscore the importance of enhancing the social environment in promoting mental health in late life through active aging.
Are diverse societies less cohesive? Testing contact and mediated contact theories
Lee, Eunro; Klik, Kathleen A.; Markus, Andrew; Hewstone, Miles; Reynolds, Katherine J.
2018-01-01
Previous research has demonstrated that there is a negative relationship between ethnic diversity in a local community and social cohesion. Often the way social cohesion is assessed, though, varies across studies and only some aspects of the construct are included (e.g., trust). The current research explores the relationship between diversity and social cohesion across a number of indicators of social cohesion including neighbourhood social capital, safety, belonging, generalized trust, and volunteering. Furthermore, social psychological theories concerning the role of positive contact and its impact on feelings of threat are investigated. Using a sample of 1070 third generation ‘majority’ Australians and structural equation modelling (SEM), findings suggest ethnic diversity is related to positive intergroup contact, and that contact showed beneficial impacts for some indicators of social cohesion both directly and indirectly through reducing perceived threat. When interethnic contact and perceived threat are included in the model there is no direct negative effect between diversity and social cohesion. The theoretical implications of these findings are outlined including the importance of facilitating opportunities for positive contact in diverse communities. PMID:29596501
The association between social cohesion and physical activity in canada: A multilevel analysis.
Yip, Calvin; Sarma, Sisira; Wilk, Piotr
2016-12-01
Although previous research has shown that social cohesion may promote physical activity, social cohesion at the individual level was not always differentiated from social cohesion at the community level, and studies were often limited to specific population subgroups or geographical areas. We addressed the above limitations through the use of a multilevel modelling approach and nationally-representative data from the 2009-2014 Canadian Community Health Survey. Physical activity level was operationalized as average daily energy expenditure; social cohesion was assessed by self-rated sense of belonging to the local community; and communities were represented by Canada's Forward Sortation Areas. The sample included 245,150 respondents from 1570 communities. Geographical location was found to explain a significant proportion (4.1%) of the overall variance in physical activity level. After adjusting for age, sex, household income, education and urban-rural status, both individual- and community-level social cohesion were found to be positively associated with physical activity (p<0.001 for both). Thus, efforts to promote social cohesion and integration within communities may also promote physical activity and overall health.
Eot-Houllier, Grégory; Magnaghi-Jaulin, Laura; Fulcrand, Géraldine; Moyroud, François-Xavier; Monier, Solange; Jaulin, Christian
2018-05-14
Sustained spindle tension applied to sister centromeres during mitosis eventually leads to uncoordinated loss of sister chromatid cohesion, a phenomenon known as "cohesion fatigue." We report that Aurora A-dependent phosphorylation of serine 7 of the centromere histone variant CENP-A (p-CENP-AS7) protects bioriented chromosomes against cohesion fatigue. Expression of a non-phosphorylatable version of CENP-A (CENP-AS7A) weakens sister chromatid cohesion only when sister centromeres are under tension, providing the first evidence of a regulated mechanism involved in protection against passive cohesion loss. Consistent with this observation, p-CENP-AS7 is detected at the inner centromere where it forms a discrete domain. The depletion or inhibition of Aurora A phenocopies the expression of CENP-AS7A and we show that Aurora A is recruited to centromeres in a Bub1-dependent manner. We propose that Aurora A-dependent phosphorylation of CENP-A at the inner centromere protects chromosomes against tension-induced cohesion fatigue until the last kinetochore is attached to spindle microtubules.
Effect of clay type on the velocity and run-out distance of cohesive sediment gravity flows
NASA Astrophysics Data System (ADS)
Baker, Megan; Baas, Jaco H.; Malarkey, Jonathan; Kane, Ian
2016-04-01
Novel laboratory experiments in a lock-exchange flume filled with natural seawater revealed that sediment gravity flows (SGFs) laden with kaolinite clay (weakly cohesive), bentonite clay (strongly cohesive) and silica flour (non-cohesive) have strongly contrasting flow properties. Knowledge of cohesive clay-laden sediment gravity flows is limited, despite clay being one of the most abundant sediment types on earth and subaqueous SGFs transporting the greatest volumes of sediment on our planet. Cohesive SGFs are particularly complex owing to the dynamic interplay between turbulent and cohesive forces. Cohesive forces allow the formation of clay flocs and gels, which increase the viscosity and shear strength of the flow, and attenuate shear-induced turbulence. The experimental SGFs ranged from dilute turbidity currents to dense debris flows. For each experiment, the run-out distance, head velocity and thickness distribution of the deposit were measured, and the flow properties were recorded using high-resolution video. Increasing the volume concentration of kaolinite and bentonite above 22% and 17%, respectively, reduced both the maximum head velocity and the run-out distances of the SGFs. We infer that increasing the concentration of clay particles enhances the opportunity for the particles to collide and flocculate, thus increasing the viscosity and shear strength of the flows at the expense of turbulence, and reducing their forward momentum. Increasing the volume concentration in the silica-flour laden flows from 1% to 46% increased the maximum head velocity, owing to the gradual increase in excess density. Thereafter, however, intergranular friction is inferred to have attenuated the turbulence, causing a rapid reduction in the maximum head velocity and run-out distance as suspended sediment concentration was increased. Moving from flows carrying bentonite via kaolinite to silica flour, a progressively larger volumetric suspended sediment concentration was needed to produce similar run-out distances and maximum head velocities. Strongly cohesive bentonite flows were able to create a stronger network of particle bonds than weakly cohesive kaolinite flows of a similar concentration, thus producing the lower maximum head velocities and run-out distances observed. The lack of cohesion in the silica-flour laden flows meant that extremely high suspended sediment concentrations, i.e. close to the cubic packing density, were required to produce a high enough frictional strength to reduce the forward momentum of these flows. These experimental results can be used to improve our understanding of the deposit geometry and run-out distance of fine-grained SGFs in the natural environment. We suggest that natural SGFs that carry weakly cohesive clays (e.g. kaolinite) reach a greater distance from their origin than flows that contain strongly cohesive clays (e.g. bentonite) at similar suspended sediment concentrations, whilst equivalent fine-grained, non-cohesive SGFs travel the furthest. In addition, weakly cohesive SGFs may cover a larger surface area and have thinner deposits, with important ramifications for the architecture of stacked event beds.
Dupuis, Marc; Studer, Joseph; Henchoz, Yves; Deline, Stéphane; Baggio, Stéphanie; N'Goran, Alexandra; Mohler-Kuo, Meichun; Gmel, Gerhard
2016-02-01
This study main purpose was the validation of both French and German versions of a Perceived Neighborhood Social Cohesion Questionnaire. The sample group comprised 5065 Swiss men from the "Cohort Study on Substance Use Risk Factors." Multigroup Confirmatory factor analysis showed that a three-factor model fits the data well, which substantiates the generalizability of Perceived Neighborhood Social Cohesion Questionnaire factor structure, regardless of the language. The Perceived Neighborhood Social Cohesion Questionnaire demonstrated excellent homogeneity (α = 95) and split-half reliability (r = .96). The Perceived Neighborhood Social Cohesion Questionnaire was sensitive to community size and participants' financial situation, confirming that it also measures real social conditions. Finally, weak but frequent correlations between Perceived Neighborhood Social Cohesion Questionnaire and alcohol, cigarette, and cannabis dependence were measured. © The Author(s) 2014.
Mode I Cohesive Law Characterization of Through-Crack Propagation in a Multidirectional Laminate
NASA Technical Reports Server (NTRS)
Bergan, Andrew C.; Davila, Carlos G.; Leone, Frank A.; Awerbuch, Jonathan; Tan, Tein-Min
2014-01-01
A method is proposed and assessed for the experimental characterization of through-the-thickness crack propagation in multidirectional composite laminates with a cohesive law. The fracture toughness and crack opening displacement are measured and used to determine a cohesive law. Two methods of computing fracture toughness are assessed and compared. While previously proposed cohesive characterizations based on the R-curve exhibit size effects, the proposed approach results in a cohesive law that is a material property. The compact tension specimen configuration is used to propagate damage while load and full-field displacements are recorded. These measurements are used to compute the fracture toughness and crack opening displacement from which the cohesive law is characterized. The experimental results show that a steady-state fracture toughness is not reached. However, the proposed method extrapolates to steady-state and is demonstrated capable of predicting the structural behavior of geometrically-scaled specimens.
NASA Astrophysics Data System (ADS)
Kievitsbosch, Robert; Smit, Hendrik; Magnanimo, Vanessa; Luding, Stefan; Taghizadeh, Kianoosh
2017-06-01
Understanding how cohesive granular materials behave is of interest for many industrial applications, such as pharmaceutical or food and civil engineering. Models of the behaviour of granular materials on the microscopic scale can be used to obtain macroscopic continuum relations by a micro-macro transition approach. The Discrete Element Method (DEM) is used to inspect the influence of cohesion on the micro and macro behaviour of granular assemblies by using an elasto-plastic cohesive contact model. Interestingly, we observe that frictional samples prepared with different cohesion values show a significant difference in pressure and coordination number in the jammed regime; the differences become more pronounced when packings are closer to the jamming density, i.e. the lowest density where the system is mechanically stable. Furthermore, we observe that cohesion has an influence on the jamming density for frictional samples, but there is no influence on the jamming density for frictionless samples.
Relation between social cohesion and team performance in soccer teams.
Tziner, Aharon; Nicola, Nicola; Rizac, Anis
2003-02-01
Investigations of the influence on team performance of team composition, in terms of task-related attributes, e.g., personality traits, cognitive abilities, often assumes this relation to be mediated by the strength (intensity) of the interpersonal relations (social cohesion) among team members. However, there has been little empirical examination of how much social cohesion actually affects team outcomes. This preliminary study sought to examine this issue using soccer teams, which have been held to resemble workplace teams. Perceptions of team cohesion were collected from 198 Israeli soccer players (comprising 36 national league teams) during the week preceding their weekly games. A significant correlation was found between the perceptions of social cohesion and the results of the soccer matches, indicating a link between team social cohesion and team performance. Implications of the results, as well as the study's limitations, are discussed, and avenues for research are suggested.
Bécares, Laia; Stafford, Mai; Laurence, James; Nazroo, James
2011-01-01
Although studies in the US have shown an association between the ethnic residential composition of an area and reports of decreased social cohesion among its residents, this association is not clear in the UK, and particularly for ethnic minority groups. The current study analyses a merged dataset from the 2005 and 2007 Citizenship Survey to assess the evidence for an association between social cohesion and ethnic residential concentration, composition and area deprivation across different ethnic groups in the UK. Results of the multilevel regression models show that, after adjusting for area deprivation, increased levels of social cohesion are found in areas of greater ethnic residential heterogeneity. Although different patterns emerge across ethnic groups and the measure of social cohesion used, findings consistently show that it is area deprivation, and not ethnic residential heterogeneity, which erodes social cohesion in the UK.
NASA Astrophysics Data System (ADS)
Sherwood, Christopher R.; Aretxabaleta, Alfredo L.; Harris, Courtney K.; Rinehimer, J. Paul; Verney, Romaric; Ferré, Bénédicte
2018-05-01
We describe and demonstrate algorithms for treating cohesive and mixed sediment that have been added to the Regional Ocean Modeling System (ROMS version 3.6), as implemented in the Coupled Ocean-Atmosphere-Wave-Sediment Transport Modeling System (COAWST Subversion repository revision 1234). These include the following: floc dynamics (aggregation and disaggregation in the water column); changes in floc characteristics in the seabed; erosion and deposition of cohesive and mixed (combination of cohesive and non-cohesive) sediment; and biodiffusive mixing of bed sediment. These routines supplement existing non-cohesive sediment modules, thereby increasing our ability to model fine-grained and mixed-sediment environments. Additionally, we describe changes to the sediment bed layering scheme that improve the fidelity of the modeled stratigraphic record. Finally, we provide examples of these modules implemented in idealized test cases and a realistic application.
Almeida, Joanna; Kawachi, Ichiro; Molnar, Beth E; Subramanian, S V
2009-09-01
Research suggests that, among Latinos, there are health benefits associated with living in a neighborhood populated with coethnics. While social networks and social cohesion are the proposed explanation for the salubrious effect and are assumed to be characteristics of Latino immigrant enclaves, evidence for this is limited. We used multilevel regression to test the relative contribution of individual race/ethnicity and neighborhood concentration of Mexican Americans as predictors of social networks and social cohesion. After accounting for personal characteristics, we found a negative association between neighborhood concentration of Mexican Americans and social cohesion. Among Latinos, living in a neighborhood with increased coethnics was associated with increased social ties. Compared to non-Latino whites, Mexican Americans reported more social ties but lower social cohesion. Contrary to the assumption that Mexican immigrant enclaves beget social cohesion, we did not find this to be true in Chicago neighborhoods.
Phillips-Salimi, Celeste R; Robb, Sheri L; Monahan, Patrick O; Dossey, Amy; Haase, Joan E
2014-01-01
To describe and compare adolescent and parent perspectives on communication, family adaptability and cohesion, as well as relationships among these variables, during the first month of an adolescent's cancer diagnosis. Seventy adolescent-parent dyads were enrolled as part of a larger multi-site study. The adolescents ranged in age from 11 to 19, and 61% were males. Parents were predominately mothers (83%). Dyads were predominately non-Hispanic Caucasian (63%). Measures included the Parent-Adolescent Communication Scale and the Family Adaptability and Cohesion Evaluation Scale (FACES II). Paired t-tests, Pearson correlations, intra-class correlation coefficients and multiple linear regression analyses were completed. Adolescent scores on communication, family adaptability and cohesion were significantly lower than parent scores. The inter-dyadic agreement between adolescents and parents was low. Communication, family adaptability and cohesion were examined separately for adolescents and for parents, and significant relationships were found. Both adolescent- and parent-perceived communication was significantly associated with family adaptability and cohesion outcomes. Differences were found in adolescent and parent perceptions of communication, family adaptability and cohesion. When both adolescents and parents had better perceived communication, this was associated with better perceived family adaptability and cohesion. Results suggest that the development of interventions to enhance adolescent-parent communication could help foster better family adaptability and cohesion, which may ultimately impact their psychological adjustment. In addition, understanding the degree to which adolescents and parents disagree on their perceptions, including the results that parents generally have more favorable perceptions, may be a useful starting point when developing interventions.
Phillips-Salimi, Celeste R.; Robb, Sheri L.; Monahan, Patrick O.; Dossey, Amy; Haase, Joan E.
2017-01-01
Purpose Describe and compare adolescent and parent perspectives on communication, family adaptability and cohesion, as well as relationships among these variables, during the first month of the adolescent’s cancer diagnosis. Methods Seventy 70 adolescent-parent dyads were enrolled as part of a larger multi-site study. Adolescents ranged in age from 11–19 and 61% were males. Parents were predominately mothers (83%). Dyads were predominately non-Hispanic Caucasian (63%). Measures included the Parent-Adolescent Communication Scale and the Family Adaptability and Cohesion Evaluation Scale (FACES II). Paired t tests, Pearson correlations, intra-class correlation coefficients, and multiple linear regression analyses were completed. Results Adolescent scores on communication, family adaptability, and cohesion were significantly lower than parent scores. The inter-dyadic agreement between adolescents and parents was low. Communication, family adaptability, and cohesion were examined separately for adolescents and for parents, significant relationships were found. Both adolescent- and parent-perceived communication was significantly associated with family adaptability and cohesion outcomes. Conclusions Differences were found in adolescent and parent perceptions of communication, family adaptability, and cohesion. When both adolescents and parents had better perceived communication, it was associated with better perceived family adaptability and cohesion. Results suggest the development of interventions to enhance adolescent-parent communication could help foster better family adaptability and cohesion which may ultimately impact their psychological adjustment. In addition, understanding the degree to which adolescents and parents disagree on their perceptions, including the results that parents generally have more favorable perceptions, may be a useful starting point when developing interventions. PMID:24501152
Seasonal variations in composite riverbank stability in the Lower Jingjiang Reach, China
NASA Astrophysics Data System (ADS)
Xia, Junqiang; Zong, Quanli; Deng, Shanshan; Xu, Quanxi; Lu, Jinyou
2014-11-01
Bank erosion is a key process in a fluvial system in the context of river dynamics and geomorphology. Since the operation of the Three Gorges Project (TGP), the Lower Jingjiang Reach (LJR) below the dam has experienced continuous channel degradation, with the phenomenon of bank erosion occurring frequently in local reaches. Therefore it is necessary to quantitatively investigate seasonal variations in the stability of composite riverbanks along the reach in order to better understand the fluvial processes in the reach. Laboratory tests were conducted for the sampled soils at six riverbanks during a field survey, with various bank soil properties being presented for the first time. These test results show that: the cohesive bank soils are relatively loose due to the high water contents of 28.5-40.0% and the low dry densities of 1.31-1.47 tonnes/m3; and the cohesion or angle of internal friction generally decreases with an increase in water content of the cohesive soil. Based on the measured cross-sectional profiles and interpolated hydrological data, the near-bank hydrodynamic conditions and soil parameters of two typical composite riverbanks were then determined during the 2007 hydrological year. An improved method was proposed for calculating the stability at the mode of cantilever failure for the overhanging block of a composite riverbank, and the stability degrees of these two riverbanks were calculated at different stages. These results reveal that: (i) the incipient velocity of the non-cohesive lower bank had a magnitude of 0.4 m/s, less than the mean near-bank velocity of about 1.0 m/s, which led to intensive basal erosion especially during the flood season; (ii) the cohesive upper bank before failure had sufficient strength to resist direct fluvial erosion, but the failed soil mass deposited in the near-bank zone was disintegrated easily with the submerged immersion and was then transported downstream by fluvial entrainment; (iii) the degree of bank stability was relatively lower during the flood season, caused by the integrated effects of a process of severe basal erosion and a lower unit weight of 8.6 kN/m3 for the submerged soil; and (iv) the degree of bank stability was lowest at the recession stage, which was caused by the vanishing of the hydrostatic confining pressure and the larger unit weight of 18.0 kN/m3 for the saturated cohesive soil, because of a rapid drawdown in the in-channel water levels with the TGP operation.
Is it Ethnic Fractionalization or Social Exclusion, Which Affects Social Cohesion?
van Staveren, Irene; Pervaiz, Zahid
2017-01-01
The theory about missing links of economic growth often lags behind the empirical estimations of such links. A consensus has emerged that ethnic fractionalization has a negative impact on growth, also when controlled for income inequality. Often, although implicitly, the assumed channel is social cohesion. We analyse the effect of fractionalization on social cohesion with a different inequality measure, namely a social measure of inequality: the Inclusion of Minorities Index. Our results indicate that it is social exclusion , which reduces social cohesion, rather than diversity as such . We conclude that future studies of social cohesion and its relation to growth may benefit from using measures of social exclusion next to ethnic diversity.
Atomistic Cohesive Zone Models for Interface Decohesion in Metals
NASA Technical Reports Server (NTRS)
Yamakov, Vesselin I.; Saether, Erik; Glaessgen, Edward H.
2009-01-01
Using a statistical mechanics approach, a cohesive-zone law in the form of a traction-displacement constitutive relationship characterizing the load transfer across the plane of a growing edge crack is extracted from atomistic simulations for use within a continuum finite element model. The methodology for the atomistic derivation of a cohesive-zone law is presented. This procedure can be implemented to build cohesive-zone finite element models for simulating fracture in nanocrystalline or ultrafine grained materials.
Leung, Lap Yin; Mao, Chen; Srivastava, Ishan; Du, Ping; Yang, Chia-Yi
2017-07-01
The purpose of this study was to demonstrate that the flow function (FFc) of pharmaceutical powders, as measured by rotational shear cell, is predominantly governed by cohesion but not friction coefficients. Driven by an earlier report showing an inverse correlation between FFc and the cohesion divided by the corresponding pre-consolidation stress (Wang et al. 2016. Powder Tech. 294:105-112), we performed analysis on a large data set containing 1130 measurements from a ring shear tester and identified a near-perfect inverse correlation between the FFc and cohesion. Conversely, no correlation was found between FFc and friction angles. We also conducted theoretical analysis and estimated such correlations based on Mohr-Coulomb failure model. We discovered that the correlation between FFc and cohesion can sustain as long as the angle of internal friction at incipient flow is not significantly larger than the angle of internal friction at steady-state flow, a condition covering almost all pharmaceutical powders. The outcome of this study bears significance in pharmaceutical development. Because the cohesion value is strongly influenced by the interparticle cohesive forces, this study effectively shows that it is more efficient to improve the pharmaceutical powder flow by lowering the interparticle cohesive forces than by lowering the interparticle frictions. Copyright © 2017 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.
Momtaz, Yadollah Abolfathi; Haron, Sharifah Azizah; Ibrahim, Rahimah; Hamid, Tengku Aizan
2014-01-01
Background The positive effect of social cohesion on well-being in older adults has been well documented. However, relatively few studies have attempted to understand the mechanisms by which social cohesion influences well-being. The main aim of the current study is to identify social pathways in which social cohesion may contribute to well-being. Methods The data for this study (taken from 1,880 older adults, aged 60 years and older) were drawn from a national survey conducted during 2008–2009. The survey employed a two-stage stratified sampling process for data collection. Structural equation modeling was used to test mediating and moderating analyses. Results The proposed model documented a good fit to the data (GFI =98; CFI =0.99; RMSEA =0.04). The findings from bootstrap analysis and the Sobel test revealed that the impact of social cohesion on well-being is significantly mediated by social embeddedness (Z=5.62; P<0.001). Finally, the results of a multigroup analysis test showed that social cohesion influences well-being through the social embeddedness mechanism somewhat differently for older men than women. Conclusion The findings of this study, in addition to supporting the importance of neighborhood social cohesion for the well-being of older adults, also provide evidence that the impact of social cohesion towards well-being is mediated through the mechanism of social embeddedness. PMID:24904206
Momtaz, Yadollah Abolfathi; Haron, Sharifah Azizah; Ibrahim, Rahimah; Hamid, Tengku Aizan
2014-01-01
The positive effect of social cohesion on well-being in older adults has been well documented. However, relatively few studies have attempted to understand the mechanisms by which social cohesion influences well-being. The main aim of the current study is to identify social pathways in which social cohesion may contribute to well-being. The data for this study (taken from 1,880 older adults, aged 60 years and older) were drawn from a national survey conducted during 2008-2009. The survey employed a two-stage stratified sampling process for data collection. Structural equation modeling was used to test mediating and moderating analyses. The proposed model documented a good fit to the data (GFI =98; CFI =0.99; RMSEA =0.04). The findings from bootstrap analysis and the Sobel test revealed that the impact of social cohesion on well-being is significantly mediated by social embeddedness (Z=5.62; P<0.001). Finally, the results of a multigroup analysis test showed that social cohesion influences well-being through the social embeddedness mechanism somewhat differently for older men than women. The findings of this study, in addition to supporting the importance of neighborhood social cohesion for the well-being of older adults, also provide evidence that the impact of social cohesion towards well-being is mediated through the mechanism of social embeddedness.
NASA Astrophysics Data System (ADS)
Ye, L.; Parsons, D. R.; Manning, A. J.
2016-12-01
Cohesive sediment, or mud, is ubiquitously found in most aqueous environments, such as coasts and estuaries. The study of cohesive sediment behaviors requires the synchronous description of mutual interactions of grains (e.g., winnowing and flocculation), their physical properties (e.g., grain size) and also the ambient water. Herein, a series of flume experiments (14 runs) with different substrate mixtures of sand-clay-EPS (Extracellular Polymeric Substrates: secreted by aquatic microorganisms) are combined with an estuarine field survey (Dee estuary, NW England) to investigate the behavior of suspensions over bio-physical cohesive substrates. The experimental results indicate that winnowing and flocculation occur pervasively in bio-physical cohesive flow systems. Importantly however, the evolution of the bed and bedform dynamics and hence turbulence production can be lower when cohesivity is high. The estuarine survey also revealed that the bio-physical cohesion provided by both the clay and microorganism fractions in the bed, that pervasively exists in many natural estuarine systems, plays a significant role in controlling the interactions between bed substrate and sediment suspension and deposition, including controlling processes such as sediment winnowing, flocculation and re-deposition. Full understanding of these processes are essential in advancing sediment transport modelling and prediction studies across natural estuarine systems and the work will report on an improved conceptual model for sediment sorting deposition in bio-physical cohesive substrates.
Zerach, Gadi; Solomon, Zahava; Horesh, Danny; Ein-Dor, Tsachi
2013-02-01
The bi-directional relationships between combat-induced posttraumatic symptoms and family relations are yet to be understood. The present study assesses the longitudinal interrelationship of posttraumatic intrusion and avoidance and family cohesion among 208 Israeli combat veterans from the 1982 Lebanon War. Two groups of veterans were assessed with self-report questionnaires 1, 3 and 20 years after the war: a combat stress reaction (CSR) group and a matched non-CSR control group. Latent Trajectories Modeling showed that veterans of the CSR group reported higher intrusion and avoidance than non-CSR veterans at all three points of time. With time, there was a decline in these symptoms in both groups, but the decline was more salient among the CSR group. The latter also reported lower levels of family cohesion. Furthermore, an incline in family cohesion levels was found in both groups over the years. Most importantly, Autoregressive Cross-Lagged Modeling among CSR and non-CSR veterans revealed that CSR veterans' posttraumatic symptoms in 1983 predicted lower family cohesion in 1985, and lower family cohesion, in turn, predicted posttraumatic symptoms in 2002. The findings suggest that psychological breakdown on the battlefield is a marker for future family cohesion difficulties. Our results lend further support for the bi-directional mutual effects of posttraumatic symptoms and family cohesion over time.
Lecomte, Tania; Leclerc, Claude; Wykes, Til
2018-03-01
Group cohesion has been linked to positive changes in self-esteem and in symptoms during group psychotherapy in people with psychosis. These changes may be linked to changes in symptoms as fluctuations in self-esteem have been linked to symptom fluctuations. We aimed to determine the relationship between these three factors - group cohesion, self-esteem, and symptoms - during group cognitive behaviour therapy for psychosis (GCBTp). We hypothesized that group cohesion would precede changes in symptoms and self-esteem and that improvements in self-esteem would precede improvements in symptoms. This is an uncontrolled longitudinal study recruiting from a convenience sample within two early psychosis clinics. Sixty-six individuals from first episode of psychosis treatment programmes participated in this study and received 24 sessions of a validated GCBTp protocol. Participants answered a brief questionnaire at the end of each session, measuring their group cohesion, self-esteem, and perception of their symptoms as worse, same, or better than usual. Orthogonal polynomial contrasts for time effects were estimated with a mixed model for repeated measures with a random cluster effect and revealed a quartic trend regarding changes in symptoms over the 24 sessions. Self-esteem, symptoms, and group cohesion were strongly linked during a given session. Also, self-esteem changes predicted changes in symptoms up to two sessions later, and symptoms changes predicted self-esteem changes at the next session. Group cohesion preceded improvements in both self-esteem and symptoms; self-esteem also predicted improvements in group cohesion. These results suggest that self-esteem and symptoms influence each other during therapy, with improvements in one leading to improvements in the other. Group cohesion also appears to be an essential prerequisite to positive changes in self-esteem and symptoms during GCBTp. This study emphasizes the interrelation between self-esteem improvements and symptom improvements, with improvements in one leading to improvements in the other, during group CBT for psychosis. Group cohesion, in this study, is a predictor of self-esteem and symptom improvements, suggesting that a special attention should be given to developing a strong alliance and group cohesion early on during CBT for psychosis. © 2017 The British Psychological Society.
DOT National Transportation Integrated Search
2015-05-01
This study of scour in cohesive soils had two objectives. The first was to introduce and demonstrate a new ex situ erosion testing device (ESTD) that can mimic the near-bed flow of open channels to erode cohesive soils within a specified range of she...
Kanesarajah, Jeeva; Waller, M; Zheng, W Y; Dobson, A J
2016-01-01
Introduction Unit cohesion has been shown to bolster the mental health of military personnel; hence, it is important to identify the characteristics that are associated with low unit cohesion, so that interventions to improve unit cohesion can be targeted and implemented. Little is known about the factors associated with low unit cohesion. This research aims to identify demographic, military service and deployment factors associated with low unit cohesion. Methods Data from a self-reported cross-sectional study of 11 411 current or ex-serving Australian military personnel deployed to Iraq or Afghanistan between 2001 and 2009 were used. Multivariable logistic regression was used to investigate the research aims. Results Being female (adjusted OR (aOR) (95% CI) 1.35 (1.21 to 1.51)), non-commissioned officer (aOR (95% CI) 1.50 (1.39 to 1.62)), lower ranked (aOR (95% CI) 1.74 (1.51 to 2.01)) or having left military service (aOR (95% CI) 1.71 (1.46 to 2.02)) was associated with reporting low unit cohesion. Potentially modifiable factors such as performing logistic roles on deployment (aOR (95% CI) 1.13 (1.01 to 1.27)), dissatisfaction with work experience on deployment such as working with colleagues who did not do what was expected of them (aOR (95% CI) 4.09 (3.61 to 4.64)), and major problems at home while deployed (aOR (95% CI) 1.50 (1.38 to 1.63)) were also associated with reporting low unit cohesion. Conclusions This is the first study to identify demographic, military service and deployment factors associated with low unit cohesion. The modifiable nature of unit cohesion means that military leaders could use this information to identify subgroups for targeted resilience interventions that may reduce vulnerabilities to mental health problems and improve the job satisfaction, preparedness and deployment experiences of serving members. PMID:26567321
Mackey, Eleanor Race; Hilliard, Marisa E; Berger, Sarah Shafer; Streisand, Randi; Chen, Rusan; Holmes, Clarissa
2011-12-01
We examined the association of youths' positive qualities, family cohesion, disease management, and metabolic control in Type 1 diabetes. Two-hundred fifty-seven youth-parent dyads completed the Family Cohesion subscale of the Family Environment Scale, the Diabetes Behavior Rating Scale, 24-hour diabetes interview, and youth completed the Positive Qualities subscale of the Youth Self Report (YSR-PQ). Structural equation modeling demonstrated that YSR-PQ scores were associated with metabolic control mediated by associations with more family cohesion and better disease management. That is, youth with higher YSR-PQ scores had more cohesive families, better disease management, and, indirectly, better metabolic control. Family cohesion was indirectly associated with better metabolic control mediated by its association with better disease management, but not mediated by its association with YSR-PQ scores. Youth who reported more positive qualities, as measured by the YSR-PQ subscale, had better disease management and metabolic control through the association with more family cohesion. However, the current results did not support an alternative hypothesis that cohesive families display better diabetes management mediated by higher YSR-PQ scores.
Analysis of Cohesion and Collective Efficacy Profiles for the Performance of Soccer Players
Leo, Francisco M.; Sánchez-Miguel, Pedro A.; Sánchez-Oliva, David; Amado, Diana; García-Calvo, Tomás
2013-01-01
The principal aims of the study were to define different profiles of cohesion and perceived efficacy in soccer players and to measure their differences in performance. The subjects were 235 soccer players in the under-18 category who played in the National League in Spain and 15 coaches whose ages ranged from 29 to 45 years. Diverse instruments to assess cohesion, perceived efficacy, and expectations of success were used in the study. Moreover, we measured playing time and performance. The results of the study proved the existence of four cohesion and efficacy profiles that presented significant differences in expectations of success, playing time, and performance. Furthermore, significant differences were found in the distribution of players in the teams as a function of performance. The main conclusion of this study is that soccer players with higher cohesion and collective efficacy levels belonged to teams that completed the season at the top-level classification. In contrast, athletes with low cohesion and collective efficacy usually played in unsuccessful teams. Coaches and sports psychologists are encouraged to promote both social and task cohesion and collective efficacy to enhance team performance. PMID:24511358
Redshaw, Sarah; Ingham, Valerie; McCutcheon, Marion; Hicks, John; Burmeister, Oliver
2018-02-01
To assess the impact of network communications, community participation and elements of vulnerability on the perception of social cohesiveness in the Blue Mountains local government area (Blue Mountains LGA). A questionnaire was administered to residents of the Blue Mountains LGA. Econometric analysis of the resulting data was undertaken. Blue Mountains LGA, Australia. One thousand one hundred and three residents of the Blue Mountains LGA responded to the questionnaire. The responses enabled the construction of variables measuring individual perceptions of community cohesiveness, their network communications and community participation. Demographic data and data on the vulnerabilities of individuals were also collected. The data were used in an econometric model which identified that network communications and community participation impacted positively on perceptions of social cohesiveness while vulnerability factors had a negative impact. Remedial action to build community cohesiveness and network communications can be expected to have a positive impact on social cohesiveness. In developing strategies to build community cohesiveness and network communication, particular care needs to be taken to ensure the inclusion of those members of society who are regarded as the most vulnerable. © 2017 National Rural Health Alliance Inc.
Team Cohesion, Player Attitude, and Performance Expectations in Simulation.
ERIC Educational Resources Information Center
Wellington, William J.; Faria, A. J.
1996-01-01
Examines the relationship of team cohesion, participant attitude, and performance expectations to actual performance results in a simulation competition. Findings indicate a strong relationship between beginning team cohesion and performance expectations and final game performance, but little relationship between beginning participant attitudes…
Of Blue Badges and Purple Cloth, the Impact of Battle Death in a Cohesive Unit
1988-12-18
the small-unit level. History shows that the key to understanding the problem of death in a cohesive unit is that the danger of being killed or...cohesion and motivation are rooted in intensely personal attachments at the small-unit level. History shows that the key to understanding the problem of...without fear of mortal peril." (8) In this one sentence he shows his awareness of the necessity for leadership and cohesiveness in the face of death
Finite cohesion due to chain entanglement in polymer melts.
Cheng, Shiwang; Lu, Yuyuan; Liu, Gengxin; Wang, Shi-Qing
2016-04-14
Three different types of experiments, quiescent stress relaxation, delayed rate-switching during stress relaxation, and elastic recovery after step strain, are carried out in this work to elucidate the existence of a finite cohesion barrier against free chain retraction in entangled polymers. Our experiments show that there is little hastened stress relaxation from step-wise shear up to γ = 0.7 and step-wise extension up to the stretching ratio λ = 1.5 at any time before or after the Rouse time. In contrast, a noticeable stress drop stemming from the built-in barrier-free chain retraction is predicted using the GLaMM model. In other words, the experiment reveals a threshold magnitude of step-wise deformation below which the stress relaxation follows identical dynamics whereas the GLaMM or Doi-Edwards model indicates a monotonic acceleration of the stress relaxation dynamics as a function of the magnitude of the step-wise deformation. Furthermore, a sudden application of startup extension during different stages of stress relaxation after a step-wise extension, i.e. the delayed rate-switching experiment, shows that the geometric condensation of entanglement strands in the cross-sectional area survives beyond the reptation time τd that is over 100 times the Rouse time τR. Our results point to the existence of a cohesion barrier that can prevent free chain retraction upon moderate deformation in well-entangled polymer melts.
NASA Astrophysics Data System (ADS)
Senkawa, K.; Nakai, Y.; Mishima, F.; Akiyama, Y.; Nishijima, S.
2011-11-01
In the industrial plants such as foods, medicines or industrial materials, there are big amount of issues on contamination by metallic wear debris originated from pipes of manufacturing lines. In this study, we developed a high gradient magnetic separation system (HGMS) under the dry process by using superconducting magnet to remove the ferromagnetic particles. One of the major problems of dry HGMS systems is, however, the blockage of magnetic filter caused by particle coagulation or deposition. In order to actualize the magnetic separation without blockage, we introduced pneumatic conveyance system as a new method to feed the powder. It is important to increase the drag force acting on the sufficiently dispersed particles, which require strong magnetic fields. To generate the strong magnetic fields, HGMS technique was examined which consists of a magnetic filter and a superconducting solenoid magnet. As a result of the magnetic separation experiment, it was shown that the separation efficiency changes due to the difference of the cohesive property of the particles. On the basis of the result, the adhesion force which acts between the ferromagnetic particles and the medium particles used for the magnetic separation was measured by Atomic Force Microscope (AFM), and cohesion of particles was studied from the aspect of interparticle interaction. We assessed a suitable flow velocity for magnetic separation according to the cohesive property of each particle based on the result.
NASA Astrophysics Data System (ADS)
Munagala, Venkata Naga Vamsi; Akinyi, Valary; Vo, Phuong; Chromik, Richard R.
2018-06-01
The powder microstructure and morphology has significant influence on the cold sprayability of Ti6Al4V coatings. Here, we compare the cold sprayability and properties of coatings obtained from Ti6Al4V powders of spherical morphology (SM) manufactured using plasma gas atomization and irregular morphology (IM) manufactured using the Armstrong process. Coatings deposited using IM powders had negligible porosity and better properties compared to coatings deposited using SM powders due to higher particle impact velocities, porous surface morphology and more deformable microstructure. To evaluate the cohesive strength, multi-scale indentation was performed and hardness loss parameter was calculated. Coatings deposited using SM powders exhibited poor cohesive strength compared to coatings deposited using IM powders. Images of the residual indents showed de-bonding and sliding of adjacent splats in the coatings deposited using SM powders irrespective of the load. Coatings deposited using IM powders showed no evidence of de-bonding at low loads. At high loads, splat de-bonding was observed resulting in hardness loss despite negligible porosity. Thus, while the powders from Armstrong process lead to a significant improvement in sprayability and coating properties, further optimization of powder and cold spray process will be required as well as consideration of post-annealing treatments to obtain acceptable cohesive strength.
Fleischer, Nancy L.; Lozano, Paula; Santillán, Edna Arillo; Shigematsu, Luz Myriam Reynales; Thrasher, James F.
2016-01-01
Background Recent increases in violent crime may impact a variety of health outcomes in Mexico. We examined relationships between neighborhood-level violence and smoking behaviors in a cohort of Mexican smokers from 2011–2012, and whether neighborhood-level social cohesion modified these relationships. Methods Data were analyzed from adult smokers and recent ex-smokers who participated in Waves 5–6 of the International Tobacco Control Mexico Survey. Self-reported neighborhood violence and social cohesion were asked of Wave 6 survey participants (n=2129 current and former smokers, n=150 neighborhoods). Neighborhood-level averages for violence and social cohesion (range 4–14 and 10–25, respectively) were assigned to individuals. We used generalized estimating equations to determine associations between neighborhood indicators and individual-level smoking intensity, quit behaviors, and relapse. Results Higher neighborhood violence was associated with higher smoking intensity (Risk Ratio (RR)=1.17, 95% Confidence Interval (CI) 1.02–1.33), and fewer quit attempts (RR=0.72, 95% CI 0.61–0.85). Neighborhood violence was not associated with successful quitting or relapse. Higher neighborhood social cohesion was associated with more quit attempts and more successful quitting. Neighborhood social cohesion modified the association between neighborhood violence and smoking intensity: in neighborhoods with higher social cohesion, as violence increased, smoking intensity decreased and in neighborhoods with lower social cohesion, as violence increased, so did smoking intensity. Conclusion In the context of recent increased violence in Mexico, smokers living in neighborhoods with more violence may smoke more cigarettes per day and make fewer quit attempts than their counterparts in less violent neighborhoods. Neighborhood social cohesion may buffer the impact of violence on smoking intensity. PMID:26043898
Facing Sorrow as a Group Unites. Facing Sorrow in a Group Divides
Rennung, Miriam; Göritz, Anja S.
2015-01-01
Collective gatherings foster group cohesion through providing occasion for emotional sharing among participants. However, prior studies have failed to disentangle two processes that are involved in emotional sharing: 1) focusing shared attention on the same emotion-eliciting event and 2) actively sharing one’s experiences and disclosing one’s feelings to others. To date, it has remained untested if shared attention influences group cohesion independent of active emotional sharing. Our experiment investigated the effect of shared versus individual attention on cohesion in groups of strangers. We predicted that differences in group cohesion as called forth by shared vs. individual attention are most pronounced when experiencing highly arousing negative affect, in that the act of experiencing intensely negative affect with others buffers negative affect’s otherwise detrimental effect on group cohesion. Two-hundred sixteen participants were assembled in groups of 3 to 4 people to either watch an emotion-eliciting film simultaneously on a common screen or to watch the same emotion-eliciting film clip on a laptop in front of each group member using earphones. The film clips were chosen to elicit either highly arousing negative affect or one of three other affective states representing the other poles in Russel’s Circumplex model of affect. We examined self-reported affective and cognitive group cohesion and a behavioral measure of group cohesion. Results support our buffer-hypothesis, in that experiencing intense negative affect in unison leads to higher levels of group cohesion than experiencing this affect individually despite the group setting. The present study demonstrates that shared attention to intense negative emotional stimuli affects group cohesion independently of active emotional sharing. PMID:26335924
Differences in neighborhood social cohesion and aerobic physical activity by Latino subgroup.
Murillo, Rosenda; Echeverria, Sandra; Vasquez, Elizabeth
2016-12-01
Previous research has examined the role of neighborhood social cohesion in physical activity outcomes; however, less is known about this relationship across Latino subgroups. The purpose of our study was to examine the association between neighborhood social cohesion and aerobic leisure-time physical activity (LTPA) among Latino adults and to determine whether these associations differ by Latino subgroup. We used cross-sectional 2013-2014 National Health Interview Survey (NHIS) data on Latinos originating from 5 countries/regions (i.e., Latinos of Puerto Rican, Mexican/Mexican-American, Cuban/Cuban-American, Dominican and Central or South American origin) aged ≥18 years (n=11,126). Multivariable logistic regression models were used to estimate associations between self-reported neighborhood social cohesion and meeting aerobic LTPA guidelines. Models were adjusted for age, sex, education, and acculturation. We also investigated whether associations varied by Latino subgroup. In adjusted models for all Latino adults, compared with those reporting low social cohesion, individuals who reported high social cohesion (Odds Ratio [OR]: 1.33; 95% Confidence Interval [CI]: 1.17-1.52) were significantly more likely to meet the aerobic physical activity guideline. When stratified by Latino subgroups, among Mexican/Mexicans-Americans (OR: 1.39; 95% CI: 1.16, 1.66) and Cuban/Cuban Americans (OR: 1.73; 95% CI: 1.00, 2.97) high social cohesion was associated with meeting the aerobic activity guideline. Among Dominicans, those who reported medium social cohesion (OR: 0.52, 95% CI: 0.29, 0.93) were less likely to meet the aerobic activity guideline. When examining aerobic physical activity outcomes in the Latino population, the role of neighborhood social cohesion and the variability among Latino subgroups should be considered.
Closson, Kalysha; Palmer, Alexis K; Collins, Alexandra B; Salters, Kate; Zhang, Wendy; Montaner, Julio S G; Hogg, Robert S; Parashar, Surita
2018-03-01
Built and social environments, including one's perception of their environment, are important determinants of health. The intersection of gender and HIV status may complicate the role of neighborhood cohesion in safety, personal well-being, and health outcomes for populations impacted by social and structural inequities. Among women in particular, social cohesion within the neighborhood they reside in may have a greater influence on health outcomes compared to their male counterparts. We sought to examine perception of neighborhood cohesion (validated scale with a range 0-100, with higher scores indicating higher perceived neighborhood cohesion) among women living with HIV, impacted by social-structural inequities, receiving combination antiretroviral therapy, and enrolled in the Longitudinal Investigations into Supportive Ancillary health services (LISA) study in British Columbia, Canada. Cross-sectional data on neighborhood cohesion and socio-demographic data were collected in an interviewer-administered survey. Of the 1,000 LISA participants interviewed, 908 (including 249 women and 659 men) had complete data for the variables of interest. At the bivariate level, women had worse perceived neighborhood cohesion scores compared to men (median: 56 [95% CI: 44-66] vs. 60 [95% CI: 47-71]). Multivariable model results indicated that for women living with HIV in our sample, greater neighborhood cohesion scores were positively associated with stable housing (β coefficient = 7.85; 95% CI: 3.61, 12.10, p < 0.001), and negatively associated with greater perceived HIV stigma (β coefficient = -1.19; 95% CI: -2.24 to-0.15; p = 0.025). The results illustrate the gendered nature of experiencing built and social environments, and highlight the need for women-centred interventions to address the social determinants of HIV burden associated with negative perceptions of neighborhood cohesion.
Occurrence of cohesion of metals during combined plastic deformation
NASA Technical Reports Server (NTRS)
Aynbinder, S. G.; Klokova, E. F.
1980-01-01
Experiments were conducted to study the cohesion of metals with surface films of varying thickness and hardness. It was established that the deformation necessary for the occurrence of cohesion is determined by the correlation of mechanical properties of the films and the base metal. The greater the relative hardness of the film the lower the deformation necessary for the occurrence of cohesion. The films are as plastic as the base metal prevent cohesion, since in this case it is impossible for sections of metal to appear that are free of contaminants. The physical perculiarities of metals that determine their capability for coalescence under conditions of dry friction are the relative hardness and plasticity of the oxide films formed on their surface under atmospheric conditions.
Validation of a brief form of the Perceived Neighborhood Social Cohesion questionnaire.
Dupuis, Marc; Baggio, Stéphanie; Gmel, Gerhard
2017-02-01
The aim of this study was the validation of a brief form of the Perceived Neighborhood Social Cohesion questionnaire using data from 5065 men from the "Cohort Study on Substance-Use Risk Factors." A 9-item scale covering three factors was proposed. Excellent indices of internal consistency were measured (α = .93). The confirmatory factor analyses resulted in acceptable fit indices supporting measurement invariance across French and German forms. Significant correlations were found between the brief form of the Perceived Neighborhood Social Cohesion questionnaire, and satisfaction and self-reported health, providing evidence of the concurrent validity of the scale. Perceived neighborhood social cohesion, and depression and suicide attempts were negatively associated, sustaining the protective effect of perceived social cohesion.
Bontrager, Sarah; Hart, Patricia L; Mareno, Nicole
2016-03-01
Thirteen percent of newly licensed registered nurses (NLRNs) vacate their first job after 1 year, and 37% report that they feel ready to change jobs. Turnover can lead to consistent and detrimental nursing shortages in nursing units, as well as increased costs for health care systems. A descriptive, prospective, cross-sectional design was used to understand how preceptor role effectiveness and group cohesion affect NLRNs' satisfaction and intent to stay. NLRNs reported high levels of perceived preceptor role effectiveness, group cohesion, and job satisfaction, with only moderate levels of intent to stay. Statistically significant relationships were found among preceptor role effectiveness, job satisfaction, and intent to stay, as well as among group cohesion, job satisfaction, and intent to stay. Preceptor role effectiveness and group cohesion are predictors of NLRNs' level of job satisfaction. Job satisfaction is a predictor of NLRNs' intent to stay. Effective preceptors and positive group cohesion are factors that are important to NLRNs' job satisfaction and intent to stay. Copyright 2016, SLACK Incorporated.
Erosion properties of cohesive sediments in the Colorado River in Grand Canyon
Akahori, R.; Schmeeckle, M.W.; Topping, D.J.; Melis, T.S.
2008-01-01
Cohesive sediment deposits characterized by a high fraction of mud (silt plus clay) significantly affect the morphology and ecosystem of rivers. Potentially cohesive sediment samples were collected from deposits in the Colorado River in Marble and Grand Canyons. The erosion velocities of these samples were measured in a laboratory flume under varying boundary shear stresses. The non-dimensional boundary shear stress at which erosion commenced showed a systematic deviation from that of non-cohesive sediments at mud fractions greater than 0.2. An empirical relation for the boundary shear stress threshold of erosion as a function of mud fraction was proposed. The mass erosion rate was modelled using the Ariathurai-Partheniades equation. The erosion rate parameter of this equation was found to be a strong function of mud fraction. Under similar boundary shear stress and sediment supply conditions in the Colorado River, cohesive lateral eddy deposits formed of mud fractions in excess of 0.2 will erode less rapidly than non-cohesive deposits. Copyright ?? 2008 John Wiley & Sons, Ltd.
A season-long team-building intervention: examining the effect of team goal setting on cohesion.
Senécal, Julie; Loughead, Todd M; Bloom, Gordon A
2008-04-01
The purpose of the current study was to determine whether the implementation of a season-long team-building intervention program using team goal setting increased perceptions of cohesion. The participants were 86 female high school basketball players from 8 teams. The teams were randomly assigned to either an experimental team goal-setting or control condition. Each participant completed the Group Environment Questionnaire (GEQ; Carron, Brawley, & Widmeyer, 2002; Carron, Widmeyer, & Brawley, 1985), which assessed cohesion at both the beginning and end of the season. Overall, the results revealed a significant multivariate effect, Pillai's trace F(12, 438) = 2.68, p = .002. Post hoc analyses showed that at the beginning of the season, athletes from both conditions did not differ in their perceptions of cohesion. However, at the end of the season, athletes in the team goal-setting condition held higher perceptions of cohesion than athletes in the control condition. Overall, the results indicated that team goal setting was an effective team-building tool for influencing cohesiveness in sport teams.
Eng, Thomas; Guacci, Vincent; Koshland, Doug
2014-01-01
Cohesin helps orchestrate higher-order chromosome structure, thereby promoting sister chromatid cohesion, chromosome condensation, DNA repair, and transcriptional regulation. To elucidate how cohesin facilitates these diverse processes, we mutagenized Mcd1p, the kleisin regulatory subunit of budding yeast cohesin. In the linker region of Mcd1p, we identified a novel evolutionarily conserved 10–amino acid cluster, termed the regulation of cohesion and condensation (ROCC) box. We show that ROCC promotes cohesion maintenance by protecting a second activity of cohesin that is distinct from its stable binding to chromosomes. The existence of this second activity is incompatible with the simple embrace mechanism of cohesion. In addition, we show that the ROCC box is required for the establishment of condensation. We provide evidence that ROCC controls cohesion maintenance and condensation establishment through differential functional interactions with Pds5p and Wpl1p. PMID:24966169
School social cohesion, student-school connectedness, and bullying in Colombian adolescents.
Springer, Andrew E; Cuevas Jaramillo, Maria Clara; Ortiz Gómez, Yamileth; Case, Katie; Wilkinson, Anna
2016-12-01
Student-school connectedness is inversely associated with multiple health risk behaviors, yet research is limited on the relative contributions of a student's connectedness with school and an overall context of school social cohesion to peer victimization/bullying. We examined associations of perceived school cohesion and student-school connectedness with physical victimization, verbal victimization, and social exclusion in the past six months in adolescents in grades 6-11 (N = 774) attending 11 public and private urban schools in Colombia. Cross-sectional data were collected via a self-administered questionnaire and analyzed using mixed-effects linear regression models. Higher perceived school cohesion was inversely related with exposure to three bullying types examined (p < 0.05); student-school connectedness was negatively related to verbal victimization among girls only (p < 0.01). In full models, school cohesion maintained inverse associations with three bullying types after controlling for student-school connectedness (p ≤ 0.05). Enhancing school cohesion may hold benefits for bullying prevention beyond a student's individual school connectedness. © The Author(s) 2015.
Glasford, Demis E; Johnston, Brian
2018-01-01
The present work explores the implications of respect for social change. Social change can be achieved via improved attitudes between minority and majority groups (i.e., social cohesion) or via action taken by minority groups (i.e., collective action). Recent work suggests that the social cohesion route to social change, in particular an emphasis on commonality, may be incompatible with the collective action route to social change. We suggest that social-cohesion strategies rooted in status-based respect may allow for social cohesion and collective action. We experimentally investigated the relative effects of a majority group communicating status-based respect and commonality, as compared to a control, on minority group members' social cohesion with the majority group and willingness to engage in collective action. Status-based respect increased positive attitudes toward a majority group, relative to commonality and control, but was also associated with increased collective action tendencies. Implications for social change are discussed.
Acculturative Stress and Diminishing Family Cohesion Among Recent Latino Immigrants
De La Rosa, Mario; Ibañez, Gladys E.
2012-01-01
This study investigates a theorized link between Latino immigrants’ experience of acculturative stress during their two initial years in the United States (US) and declines in family cohesion from pre- to post-immigration contexts. This retrospective cohort study included 405 adult participants. Baseline assessment occurred during participants’ first 12 months in the US. Follow-up assessment occurred during participants’ second year in the US. General linear mixed models were used to estimate change in family cohesion and sociocultural correlates of this change. Inverse associations were determined between acculturative stress during initial years in the US and declines in family cohesion from pre-immigration to post-immigration contexts. Participants with undocumented immigration status, those with lower education levels, and those without family in the US generally indicated lower family cohesion. Participants who experienced more acculturative stress and those without family in the US evidenced a greater decline in family cohesion. Results are promising in terms of implications for health services for recent Latino immigrants. PMID:22790880
Sisters Unbound Is Required for Meiotic Centromeric Cohesion in Drosophila melanogaster
Krishnan, Badri; Thomas, Sharon E.; Yan, Rihui; Yamada, Hirotsugu; Zhulin, Igor B.; McKee, Bruce D.
2014-01-01
Regular meiotic chromosome segregation requires sister centromeres to mono-orient (orient to the same pole) during the first meiotic division (meiosis I) when homologous chromosomes segregate, and to bi-orient (orient to opposite poles) during the second meiotic division (meiosis II) when sister chromatids segregate. Both orientation patterns require cohesion between sister centromeres, which is established during meiotic DNA replication and persists until anaphase of meiosis II. Meiotic cohesion is mediated by a conserved four-protein complex called cohesin that includes two structural maintenance of chromosomes (SMC) subunits (SMC1 and SMC3) and two non-SMC subunits. In Drosophila melanogaster, however, the meiotic cohesion apparatus has not been fully characterized and the non-SMC subunits have not been identified. We have identified a novel Drosophila gene called sisters unbound (sunn), which is required for stable sister chromatid cohesion throughout meiosis. sunn mutations disrupt centromere cohesion during prophase I and cause high frequencies of non-disjunction (NDJ) at both meiotic divisions in both sexes. SUNN co-localizes at centromeres with the cohesion proteins SMC1 and SOLO in both sexes and is necessary for the recruitment of both proteins to centromeres. Although SUNN lacks sequence homology to cohesins, bioinformatic analysis indicates that SUNN may be a structural homolog of the non-SMC cohesin subunit stromalin (SA), suggesting that SUNN may serve as a meiosis-specific cohesin subunit. In conclusion, our data show that SUNN is an essential meiosis-specific Drosophila cohesion protein. PMID:25194162
Lee, Bo Ram; Sum, Amadeu K
2015-04-07
To prevent hydrate plugging conditions in the transportation of oil/gas in multiphase flowlines, one of the key processes to control is the agglomeration/deposition of hydrate particles, which are determined by the cohesive/adhesive forces. Previous studies reporting measurements of the cohesive/adhesive force between hydrate particles used cyclopentane hydrate particles in a low-pressure micromechanical force apparatus. In this study, we report the cohesive forces of particles measured in a new high-pressure micromechanical force (MMF) apparatus for ice particles, mixed (methane/ethane, 74.7:25.3) hydrate particles (Structure II), and carbon dioxide hydrate particles (Structure I). The cohesive forces are measured as a function of the contact time, contact force, temperature, and pressure, and determined from pull-off measurements. For the measurements performed of the gas hydrate particles in the gas phase, the determined cohesive force is about 30-35 mN/m, about 8 times higher than the cohesive force of CyC5 hydrates in the liquid CyC5, which is about 4.3 mN/m. We show from our results that the hydrate structure (sI with CO2 hydrates and sII with CH4/C2H6 hydrates) has no influence on the cohesive force. These results are important in the deposition of a gas-dominated system, where the hydrate particles formed in the liquid phase can then stick to the hydrate deposited in the wall exposed to the gas phase.
English, Devin; Busby, Danielle R.; Lambert, Sharon F.; Harrison, Aubrey; Stock, Michelle L.; Gibbons, Frederick X.
2016-01-01
Parental racial socialization is a parenting tool used to prepare African American adolescents for managing racial stressors. While it is known that parents’ racial discrimination experiences affect the racial socialization messages they provide, little is known about the influence of factors that promote supportive and communal parenting, such as perceived neighborhood cohesion. In cohesive neighborhoods, neighbors may help parents address racial discrimination by monitoring youth and conveying racial socialization messages; additionally, the effect of neighborhood cohesion on parents’ racial socialization may differ for boys and girls because parents socialize adolescents about race differently based on expected encounters with racial discrimination. Therefore, the current study examines how parents’ perception of neighborhood cohesion and adolescents’ gender moderate associations between parents’ racial discrimination experiences and the racial socialization messages they deliver to their adolescents. Participants were a community sample of 608 African American adolescents (54 % girls; mean age = 15.5) and their primary caregivers (86 % biological mothers; mean age = 42.0). Structural equation modeling indicated that parental racial discrimination was associated with more promotion of mistrust messages for boys and girls in communities with low neighborhood cohesion. In addition, parental racial discrimination was associated with more cultural socialization messages about racial pride and history for boys in neighborhoods with low neighborhood cohesion. The findings suggest that parents’ racial socialization messages are influenced by their own racial discrimination experiences and the cohesiveness of the neighborhood; furthermore, the content of parental messages delivered varies based on adolescents’ gender. PMID:27189721
Ultimate pier and contraction scour prediction in cohesive soils at selected bridges in Illinois.
DOT National Transportation Integrated Search
2013-09-01
The Scour Rate In COhesive Soils-Erosion Function Apparatus (SRICOS-EFA) method includes an ultimate scour prediction that is : the equilibrium maximum pier and contraction scour of cohesive soils over time. The purpose of this report is to present t...
Community Cohesion: A Report of the Independent Review Team.
ERIC Educational Resources Information Center
Home Office, London (England).
This study examined the views of English citizens and community leaders regarding problems related to disaffected, disadvantaged, culturally diverse groups. The Community Cohesion Review Team (CCRT) investigated issues needing to be addressed to bring about social cohesion. Communities were deeply polarized, with separate educational systems,…
Social Cohesion and Voluntary Associations
ERIC Educational Resources Information Center
Heuser, Brian L.
2005-01-01
Voluntary organizations exert great influence over how social norms and ethical codes are guided into action. As such, they have a significant impact on societal levels of social cohesion. Although social capital involves generalized trust becoming manifest as spontaneous sociability, social cohesion is determined by how that sociability is…
1992-06-16
other things, they must consider deployment issues, coalition partners, pregnancy, unit cohesion, strength issues, sexual harassment and fraternization...Among other things, they must consider deployment issues, coalition partners, pregnancy, unit cohesion, strength issues. sexual harassment and...11 Deployment Issues - Pregnancy/Absenteeism ... ...... 12 Unit Cohesion and Bonding .... .............. ... 14 Sexual Harassment
Influence of Sport Education on Group Cohesion in University Physical Education
ERIC Educational Resources Information Center
Jenkins, Jayne M.; Alderman, Brandon L.
2011-01-01
The Sport Education ("SE") curricular model incorporated within university physical education Basic Instruction Program (BIP) may increase group cohesion. This study's purpose was to identify student perceptions of a BIP course taught within "SE," and investigate group cohesion in differing activity content. Participants…
Group Cohesiveness in the Industrial Work Group.
ERIC Educational Resources Information Center
Seashore, Stanley E.
Originally published in 1954, this investigation was designed to explore the formation of cohesiveness within work groups in an industrial setting, and the relationship of cohesiveness to productivity and to group members' mental health and adjustment. A company wide questionnaire survey, involving 228 groups totaling 5,871 workers, was made of…
A Reappraisal of Lexical Cohesion in Conversational Discourse
ERIC Educational Resources Information Center
Gomez Gonzalez, Maria De Los Angeles
2013-01-01
Cohesion, or the connectedness of discourse, has been recognized as playing a crucial role in both language production and comprehension processes. Researchers have debated about the "right" number and classification of cohesive devices, as well as about their interaction with coherence and/or genre. The present study proposes an integrative model…
Cohesion and Coherence in Theory and Reading Research.
ERIC Educational Resources Information Center
Fulcher, Glenn
1989-01-01
Examines the conflict between applied linguistics and schema theoreticians over the relationship between the concepts of cohesion and coherence. Suggests that the positions taken are the result of theoretically different starting points. Reports the results of two studies that support the theory accounting for cohesion and coherence. (RS)
Cohesion Features in ESL Reading: Comparing Beginning, Intermediate and Advanced Textbooks
ERIC Educational Resources Information Center
Plakans, Lia; Bilki, Zeynep
2016-01-01
This study of English as a second language (ESL) reading textbooks investigates cohesion in reading passages from 27 textbooks. The guiding research questions were whether and how cohesion differs across textbooks written for beginning, intermediate, and advanced second language readers. Using a computational tool called Coh-Metrix, textual…
Academic Social Cohesion within Higher Education
ERIC Educational Resources Information Center
Heuser, Brian L.
2007-01-01
This article explores the theoretical foundations of "social cohesion" as it relates to higher education institutions. In so doing it seeks (a) to understand the core elements of social cohesion--social capital, human capital and ethical behavioral norms that serve a common good--and (b) to establish a flexible framework for understanding the…
Religious Communities, Immigration, and Social Cohesion in Rural Areas: Evidence from England
ERIC Educational Resources Information Center
Andrews, Rhys
2011-01-01
Religious communities are important sources of bridging and bonding social capital that have varying implications for perceptions of social cohesion in rural areas. In particular, as well as cultivating cohesiveness more broadly, the bridging social capital associated within mainline religious communities may represent an especially important…
Family Cohesion in the Lives of Mexican American and European American Parents
ERIC Educational Resources Information Center
Behnke, Andrew O.; MacDermid, Shelley M.; Coltrane, Scott L.; Parke, Ross D.; Duffy, Sharon; Widaman, Keith F.
2008-01-01
This study investigated similarities and differences in relations between stress and parenting behaviors for 509 Mexican American and European American fathers and mothers in Southern California. Our model posited that family cohesion mediates the relation between stressors and parenting behavior, and we found that family cohesion strongly…
Cohesion in Online Student Teams versus Traditional Teams
ERIC Educational Resources Information Center
Hansen, David E.
2016-01-01
Researchers have found that the electronic methods in use for online team communication today increase communication quality in project-based work situations. Because communication quality is known to influence group cohesion, the present research examined whether online student project teams are more cohesive than traditional teams. We tested…
Effective particle sizes of cohesive sediment in north Mississippi streams
USDA-ARS?s Scientific Manuscript database
Knowledge of the size of cohesive sediment particles transported in streams is important information for predicting how the sediment and contaminants the sediment may be carrying will be transported by the flow. Cohesive sediments (less than 0.062 mm in diameter) generally are not transported in th...
Natural disasters and indicators of social cohesion.
Calo-Blanco, Aitor; Kovářík, Jaromír; Mengel, Friederike; Romero, José Gabriel
2017-01-01
Do adversarial environmental conditions create social cohesion? We provide new answers to this question by exploiting spatial and temporal variation in exposure to earthquakes across Chile. Using a variety of methods and controlling for a number of socio-economic variables, we find that exposure to earthquakes has a positive effect on several indicators of social cohesion. Social cohesion increases after a big earthquake and slowly erodes in periods where environmental conditions are less adverse. Our results contribute to the current debate on whether and how environmental conditions shape formal and informal institutions.
Natural disasters and indicators of social cohesion
Calo-Blanco, Aitor; Kovářík, Jaromír; Mengel, Friederike; Romero, José Gabriel
2017-01-01
Do adversarial environmental conditions create social cohesion? We provide new answers to this question by exploiting spatial and temporal variation in exposure to earthquakes across Chile. Using a variety of methods and controlling for a number of socio-economic variables, we find that exposure to earthquakes has a positive effect on several indicators of social cohesion. Social cohesion increases after a big earthquake and slowly erodes in periods where environmental conditions are less adverse. Our results contribute to the current debate on whether and how environmental conditions shape formal and informal institutions. PMID:28591148
Numerical insight into the micromechanics of jet erosion of a cohesive granular material
NASA Astrophysics Data System (ADS)
Cuéllar, Pablo; Benseghier, Zeyd; Luu, Li-Hua; Bonelli, Stéphane; Delenne, Jean-Yves; Radjaï, Farhang; Philippe, Pierre
2017-06-01
Here we investigate the physical mechanisms behind the surface erosion of a cohesive granular soil induced by an impinging jet by means of numerical simulations coupling fluid and grains at the microscale. The 2D numerical model combines the Discrete Element and Lattice Boltzmann methods (DEM-LBM) and accounts for the granular cohesion with a contact model featuring a paraboloidal yield surface. Here we review first the hydrodynamical conditions imposed by the fluid jet on a solid granular packing, turning then the attention to the impact of cohesion on the erosion kinetics. Finally, the use of an additional subcritical debonding damage model based on the work of Silvani and co-workers provides a novel insight into the internal solicitation of the cohesive granular sample by the impinging jet.
Liu, Freda F; Goto, Sharon G
2007-04-01
The interactive effects between interdependent and independent self-construal on family cohesion and mental distress were examined. Survey responses from 153 Asian American high school students supported the hypothesized moderation of interdependence by independence on family cohesion, which was found to further mediate the relationship between self-construal and mental distress. Specifically, interdependence was positively associated with family cohesion when independence was high and negatively associated with family cohesion when independence was low. Accounting for the mediator effects of family cohesion, mental distress was positively associated with interdependence and more so for those low on independence than those high on independence. The benefits of biculturalism and research implications for the bidimensional conceptualization of self-construal for ethnic minority populations are discussed. (c) 2007 APA, all rights reserved.
Transformational leadership and task cohesion in sport: the mediating role of inside sacrifice.
Cronin, Lorcan Donal; Arthur, Calum Alexander; Hardy, James; Callow, Nichola
2015-02-01
In this cross-sectional study, we examined a mediational model whereby transformational leadership is related to task cohesion via sacrifice. Participants were 381 American (Mage = 19.87 years, SD = 1.41) Division I university athletes (188 males, 193 females) who competed in a variety of sports. Participants completed measures of coach transformational leadership, personal and teammate inside sacrifice, and task cohesion. After conducting multilevel mediation analysis, we found that both personal and teammate inside sacrifice significantly mediated the relationships between transformational leadership behaviors and task cohesion. However, there were differential patterns of these relationships for male and female athletes. Interpretation of the results highlights that coaches should endeavor to display transformational leadership behaviors as they are related to personal and teammate inside sacrifices and task cohesion.
Family Cohesion and its Relationship to Psychological Distress among Latino Groups
Rivera, Fernando I.; Guarnaccia, Peter J.; Mulvaney-Day, Norah; Lin, Julia Y.; Torres, Maria; Alegria, Margarita
2009-01-01
This paper presents analyses of a representative sample of US Latinos (N=2540) to investigate whether family cohesion moderates the effects of cultural conflict on psychological distress. The results for the aggregated Latino group suggests a significant association between family cohesion and lower psychological distress and the combination of strong family cohesion with presence of family cultural conflict was associated with higher psychological distress. However, this association differed by Latino groups. We found no association for Puerto Ricans, Cuban results were similar to the aggregate group, family cultural conflict in Mexicans was associated with higher psychological distress, while family cohesion in Other Latinos was associated with higher psychological distress. Implications of these findings are discussed to unravel the differences in family dynamics across Latino subethnic groups. PMID:19444326
Welsh, Ericka M; French, Simone A; Wall, Melanie
2011-01-01
To confirm previously reported associations between family meal frequency and dietary intake, and to examine family cohesion as a potential mediator of this relationship. Cross-sectional observational study. Data collected at baseline via questionnaire. Randomized, controlled household weight gain prevention trial. Participants were 152 adults and 75 adolescents from 90 community households. Family meal frequency assessed with a single question. Perceived family cohesion measured by the Family Adaptability and Cohesion Evaluation Scale-III. Usual intake of targeted food items assessed with modified food frequency questionnaire. Hierarchical linear regression with mediation analysis. Statistical significance set at α-level .05. Family meal frequency was associated with intake of fruits and vegetables in adults, and sweets and sugar-sweetened beverages in adolescents. Family meal frequency was positively correlated with perceived family cohesion (r = 0.41, P < .01). Partial mediation by family cohesion was observed for family meal frequency and sweets intake in adolescents. Results suggest that family cohesion is not a consistent mediator of relationship between family meal frequency and individual dietary intake. Future studies should assess additional plausible mediators of this relationship in order to better understand the effect of family meals on dietary intake. Copyright © 2011 Society for Nutrition Education. Published by Elsevier Inc. All rights reserved.
The influence of text cohesion and picture detail on young readers' knowledge of science topics.
Désiron, Juliette C; de Vries, Erica; Bartel, Anna N; Varahamurti, Nalini
2017-10-16
The effects of text cohesion and added pictures on acquired knowledge have been heavily studied each in isolation. Furthermore, studies on the effects of specific characteristics of pictures, whether facilitating or hindering, are scarce. Schnotz's ITCP Model (2014) allows to formulate hypotheses regarding the combined effect of text cohesion and presence and level of detail of a picture. This study investigates these hypotheses in the case of children reading scientific texts. One hundred and one-second-, third-, and fourth-grade pupils with a mean age of 9 years, in the western United States. Data were collected over three sessions to encompass an understanding of each pupil's knowledge based on prior sessions. Results showed a significant increase in pupils' knowledge between pre-test and immediate post-test, but as hypothesized, no significant difference between levels of cohesion. No significant difference between types of pictures was detected. After 1 week, knowledge built with a high cohesive text significantly dropped with low-detail picture, whereas, with high detail, or no picture, there was no significant difference. Results suggested that when participants were given a low-detail picture with a low cohesive text, the integration process of the material was more restricted than with a high cohesive text. © 2017 The British Psychological Society.
Role of Securin, Separase and Cohesins in female meiosis and polar body formation in Drosophila.
Guo, Zhihao; Batiha, Osamah; Bourouh, Mohammed; Fifield, Eric; Swan, Andrew
2016-02-01
Chromosome segregation in meiosis is controlled by a conserved pathway that culminates in Separase-mediated cleavage of the α-kleisin Rec8, leading to dissolution of cohesin rings. Drosophila has no gene encoding Rec8, and the absence of a known Separase target raises the question of whether Separase and its regulator Securin (Pim in Drosophila) are important in Drosophila meiosis. Here, we investigate the role of Securin, Separase and the cohesin complex in female meiosis using fluorescence in situ hybridization against centromeric and arm-specific sequences to monitor cohesion. We show that Securin destruction and Separase activity are required for timely release of arm cohesion in anaphase I and centromere-proximal cohesion in anaphase II. They are also required for release of arm cohesion on polar body chromosomes. Cohesion on polar body chromosomes depends on the cohesin components SMC3 and the mitotic α-kleisin Rad21 (also called Vtd in Drosophila). We provide cytological evidence that SMC3 is required for arm cohesion in female meiosis, whereas Rad21, in agreement with recent findings, is not. We conclude that in Drosophila meiosis, cohesion is regulated by a conserved Securin-Separase pathway that targets a diverged Separase target, possibly within the cohesin complex. © 2016. Published by The Company of Biologists Ltd.
Horsfield, Julia A.; Print, Cristin G.; Mönnich, Maren
2012-01-01
The multi-subunit protein complex, cohesin, is responsible for sister chromatid cohesion during cell division. The interaction of cohesin with DNA is controlled by a number of additional regulatory proteins. Mutations in cohesin, or its regulators, cause a spectrum of human developmental syndromes known as the “cohesinopathies.” Cohesinopathy disorders include Cornelia de Lange Syndrome and Roberts Syndrome. The discovery of novel roles for chromatid cohesion proteins in regulating gene expression led to the idea that cohesinopathies are caused by dysregulation of multiple genes downstream of mutations in cohesion proteins. Consistent with this idea, Drosophila, mouse, and zebrafish cohesinopathy models all show altered expression of developmental genes. However, there appears to be incomplete overlap among dysregulated genes downstream of mutations in different components of the cohesion apparatus. This is surprising because mutations in all cohesion proteins would be predicted to affect cohesin’s roles in cell division and gene expression in similar ways. Here we review the differences and similarities between genetic pathways downstream of components of the cohesion apparatus, and discuss how such differences might arise, and contribute to the spectrum of cohesinopathy disorders. We propose that mutations in different elements of the cohesion apparatus have distinct developmental outcomes that can be explained by sometimes subtly different molecular effects. PMID:22988450
Lehan, Tara J; Stevens, Lillian Flores; Arango-Lasprilla, Juan Carlos; Díaz Sosa, Dulce María; Espinosa Jove, Irma Guadalupe
2012-01-01
Much of what is known about family functioning in the face of traumatic brain injury (TBI) is based on research conducted in the United States. The purpose of this study was to (1) describe the levels of family adaptability, cohesion, communication, and satisfaction as reported by Mexican TBI survivors and their family caregivers, (2) test the hypothesis of the Circumplex Model that balanced families would exhibit better communication and greater satisfaction, and (3) explore how TBI survivors' and their family caregivers' perceptions of family adaptability and cohesion influenced their own and the other's perceptions of family communication and satisfaction. In the majority of dyads, both the TBI survivor and the family caregiver endorsed balanced family adaptability and cohesion. Both TBI survivors and their family caregivers reported a relatively high level of family communication and satisfaction. TBI survivors and family caregivers who reported greater levels of family adaptability and cohesion also endorsed better family communication and greater family satisfaction. In addition, individuals with TBI whose family caregiver endorsed balanced family adaptability and cohesion reported better family communication. Further, family caregivers of TBI survivors who reported balanced family adaptability and cohesion reported better family communication. Implications for research and practice are discussed.
The role of bio-physical cohesive substrates on sediment winnowing and bedform development
NASA Astrophysics Data System (ADS)
Ye, Leiping; Parsons, Daniel; Manning, Andrew
2017-04-01
Existing sediment transport and bedform size predictions for natural open-channel flows in many environments are seriously impeded by a lack of process-based knowledge concerning the dynamics of complex bed sediment mixtures comprising cohesionless sand and biologically-active cohesive muds. A series of flume experiments (14 experimental runs) with different substrate mixtures of sand-clay-EPS (Extracellular Polymeric Substance) are combined with a detailed estuarine field survey (Dee estuary, NW England) to investigate the development of bedform morphologies and characteristics of suspended sediment over bio-physical cohesive substrates. The experimental results indicate that winnowing and sediment sorting can occur pervasively in bio-physical cohesive sediment - flow systems. Importantly however, the evolution of the bed and bedform dynamics, and hence turbulence production, is significantly reduced as bed substrate cohesivity increases. The estuarine subtidal zone survey also revealed that the bio-physical cohesion provided by both the clay and microorganism fractions in the bed plays a significant role in controlling the interactions between bed substrate and sediment suspension, deposition and bedform generation. The work will be presented here concludes by outlining the need to extend and revisit the effects of cohesivity in morphodynamic systems and the sets of parameters presently used in numerical modelling, particularly in the context of the impact of climate change on estuarine and coastal systems.
Depth-dependent erodibility: representing burnt soils as a two-layered cohesive/non-cohesive system
NASA Astrophysics Data System (ADS)
Nyman, P.; Sheridan, G. J.; Moody, J. A.; Smith, H. G.; Lane, P. N.
2011-12-01
Immediately after wildfire there is an abundant supply of non-cohesive ash, soil and gravel which is easily entrained by overland flow. Under these conditions the sediment flux on hillslopes can be assumed to be equal to the transport capacity of the flow. However, the supply of material is finite and at some point the hillslope could shift towards a system where entrainment is restricted by armouring and soil cohesion. In this study we test the notion that burnt hillslopes can be represented as a two-layered system of non-cohesive and cohesive soils. Using a combination of i) shear vane measurements, ii) confined hillslope flow experiments and iii) a laboratory flume, we demonstrate how erosion on burnt hillslopes primarily takes place in a distinct layer of non-cohesive soil with erosion properties that are very different to the underlying soil matrix. Shear vane measurements were taken at 5 soil depths at more than 50 points along transects in order to quantify the depth and spatial distribution of non-cohesive soil in two small (0.5 ha) and steep (30 deg) convergent basins (SE Australia) that were burnt at high severity. The measurements showed that the recently burnt hillslopes were mantled with non-cohesive soil to an average depth of 18mm and 20mm at the two sites which were situated in different geologic terrain but in similar eucalyptus dominated forests. In the hillslope flow experiments, the rapid entrainment of non-cohesive material resulted in very high sediment concentration (50-60% by volume) in the initial surge from the test area. During the flow experiments the sediment concentration decreased exponentially with time until the erosion rate reached a steady state reflecting the erodibility of the underlying cohesive soil. The formation of shallow rills and the presence of large clasts (>16cm) within the test area resulted in incomplete removal of the non-cohesive material at shear stress < 50 Ncm-2. At shear stress > 50 Ncm-2 all material was removed, and the erosion depth at the end of the experiments was equal to the depth of non-cohesive material measured using the shear vane. In a separate set of experiments, a laboratory flume was used to measure the erodibility at different soil depths using soil cores that were burnt at moderate to high severity. Unlike the field based flow experiments, the erodibility measurements of non-cohesive soils in the flume were not restricted by the transport capacity of the flow. Results from the flume experiments showed a two order of magnitude decrease in erodibility within the top 2cm of the soil profile for soil cores from both chaparral and coniferous forests (western US). In summary, these results indicate that a majority of hillslope sediment may be generated from a relatively shallow layer of non-cohesive and highly erodible material. The depth of this material may be an important property that can help determine the post-fire erosion and debris flow potential, particularly in systems where other sources of sediment are limited. The study confirms that erodibility of burnt soil shows strong variation with depth and that the assumption of a constant erodibility factor may lead to misrepresentation of important processes.
The effect of biological cohesion on current ripple development
NASA Astrophysics Data System (ADS)
Malarkey, Jonathan; Baas, Jaco H.; Hope, Julie
2014-05-01
Results are presented from laboratory experiments examining the role of biological cohesion, associated with Extra Polymeric Substances, on the development of current ripples. The results demonstrate the importance of biological cohesion compared to the effect of physical cohesion associated with clays in an otherwise sandy bed. FURTHER INFORMATION In fluvial and marine environments sediment transport is mainly dependent on the nature of the bed surface (rippled or flat) and the nature of cohesion in the bed. Cohesion can be either physical, as a result of the presence of clays, or biological as a result of the presence of organisms. In the case of the latter, biological cohesion occurs as a result of the presence of Extra Polymeric Substances (EPS) secreted by microorganisms. While it is known that EPS can dramatically increase the threshold of motion (Grant and Gust, 1987), comparatively little is known about the effect of EPS on ripple formation and development. The experiments described here seek to fill this gap. They also allow the effect of biological cohesion to be compared with that of physical cohesion from previous experiments (Baas et al., 2013). The experiments, which were conducted in a 10m flume at Bangor University, involved a current over a bed made of fine sand, with a median diameter of 0.148mm, and various amounts of xanthan gum, a proxy for naturally occurring EPS (Vardy et al., 2007). The hydrodynamic experimental conditions were matched very closely to those of Baas et al. (2013). The ripple dimensions were recorded through the glass side wall of the tank using time lapse photography. In the physical cohesion experiments of Baas et al. (2013) for clay contents up to 12%, the clay was very quickly winnowed out of the bed, leaving essentially clay-free ripples that developed at more or less the same rate as clean sand ripples. The resulting equilibrium ripples were essentially the same length as the clean sand ripples but reduced in height. By contrast, the biological cohesion experiments resulted in a drastic slowing down in ripple development, for much smaller amounts of xanthan (< 1/8%), but resulted in equilibrium ripples with the same dimensions as abiotic sand. This difference in effect for biological and physical cohesion is thought to be related to differences in the nature of the binding. In particular, sand grains with biological cohesion are inhibited from moving independently, which is crucial to ripple development. This work has profound implications for sediment transport studies and emphasises the importance of considering biology as well as clays in sediments. ACKNOWLEDGEMENTS This work was funded by the UK Natural Environment Research Council (NERC) under the 'COHBED' project (NE/1027223/1). REFERENCES Baas, J.H., Davies, A.G. and Malarkey, A.G. (2013) Bedform development in mixed sand-mud: the contrasting role of cohesive forces in flow and bed. Geomorphology, 182, 19-32. Grant, J. and Gust, G. (1987) Prediction of coastal sediment stability from photopigment content of mats of purple sulfur bacteria. Nature, 330, 244-246. Vardy, S., Saunders, J.E., Tolhurst, T.J., Davies, P.A., and Paterson, D.M. (2007) Calibration of the high-pressure cohesive strength meter (CSM). Continental Shelf Research, 27, 1190-1199.
Kim, Cheon-Jei; Hwang, Ko-Eun; Song, Dong-Heon; Jeong, Tae-Jun; Kim, Hyun-Wook
2015-01-01
The effects of reducing fat levels from 30% to 20% and salt concentrations from 1.5% to 1.0% by partially substituting incorporated phosphate and sea mustard were investigated based on physicochemical properties of reduced-fat / low-NaCl meat emulsion systems. Cooking loss and emulsion stability, hardness, springiness, and cohesiveness for reduced-fat / low-NaCl meat emulsion systems with 20% pork back fat and 1.2% sodium chloride samples with incorporation of phosphate and sea mustard were similar to the control with 30% pork back fat and 1.5% sodium chloride. Results showed that reduced-fat / low-NaCl meat emulsion system samples containing phosphate and sea mustard had higher apparent viscosity. The results of this study show that the incorporation of phosphate and sea mustard in the formulation will successfully reduce fat and salt in the final meat products. PMID:26761874
A critical approach to the definition of Darwinian units of selection.
Rinkevich, B
2000-12-01
What are the biological units of selection? In fact, the notion of "unit of selection" (UOS) is blurred by ambiguity and controversy. To further evaluate the biological entities that are the objects of natural selection, three novel conceptual criteria (holism, minimalism, functionalism) are critically applied; they reveal, in addition to the self-evident case of the "individual," at least six distinct types of UOSs. These UOSs do not always have a defined structural organization; they can be parts of a living organism, a cohesive group of conspecifics, a multiunit entity, a totipotent cell, a DNA fragment, or a whole organism. UOS types diversify by amalgamation or parcelation processes of apparent entities. Therefore, previous attempts to characterize the UOSs solely on some morphological levels (gene, individual, group) without applying stringent criteria have failed to cope with the structural variations of natural phenomena and have led to the ambiguity of terms used.
Choi, Yun-Sang; Choi, Ji-Hun; Han, Doo-Jeong; Kim, Hack-Youn; Lee, Mi-Ai; Kim, Hyun-Wook; Lee, Ju-Woon; Chung, Hai-Jung; Kim, Cheon-Jei
2010-01-01
The effects of reducing pork fat levels from 30% to 20% and partially substituting the pork fat with a mix of grape seed oil (0%, 5%, 10% and 15%) and 2% rice bran fiber were investigated based on chemical composition, cooking characteristics, physicochemical and textural properties, and viscosity of reduced-fat meat batters. For reduced-fat meat batters containing grape seed oil and rice bran fiber the moisture and ash contents, uncooked and cooked pH values, yellowness, cohesiveness, gumminess, chewiness, and sarcoplasmic protein solubility were higher than in the control samples. The reduced-fat samples with increasing grape seed oil concentrations had lower cooking loss, emulsion stability, and apparent viscosity. The incorporation of grape seed oil and rice bran fiber successfully reduced the animal fat content in the final products while improving other characteristics.
Rheology of wet granular materials under continuous shear: experiments and simulations
NASA Astrophysics Data System (ADS)
Badetti, Michel; Fall, Abdoulaye; Roux, Jean-Noël
2017-06-01
The behaviour of wet granular media in shear flow is characterized by the dependence of apparent friction μ* and solid fraction Φs on the reduced pressure P* and the inertia number I. Reduced pressure, P* = σ22a2/F0, compares the applied normal stress σ22 on grains of diameter a to the tensile strength of contact F0 (proportional to the surface tension D of the liquid and the beads diameter). A specifically modified rotational rheometer is used to characterize the response of model wet granular material to applied shear rate \\dot γ under controlled normal stress σ22. Discrete Element Method (DEM) simulations in 3D are carried out in parallel and numerical results are compared with experimental ones. Cohesive, inertia, saturation and viscous effects on macroscopic coefficient of friction μ* and solid fraction Φs are discussed.
Kanesarajah, Jeeva; Waller, M; Zheng, W Y; Dobson, A J
2016-10-01
Unit cohesion has been shown to bolster the mental health of military personnel; hence, it is important to identify the characteristics that are associated with low unit cohesion, so that interventions to improve unit cohesion can be targeted and implemented. Little is known about the factors associated with low unit cohesion. This research aims to identify demographic, military service and deployment factors associated with low unit cohesion. Data from a self-reported cross-sectional study of 11 411 current or ex-serving Australian military personnel deployed to Iraq or Afghanistan between 2001 and 2009 were used. Multivariable logistic regression was used to investigate the research aims. Being female (adjusted OR (aOR) (95% CI) 1.35 (1.21 to 1.51)), non-commissioned officer (aOR (95% CI) 1.50 (1.39 to 1.62)), lower ranked (aOR (95% CI) 1.74 (1.51 to 2.01)) or having left military service (aOR (95% CI) 1.71 (1.46 to 2.02)) was associated with reporting low unit cohesion. Potentially modifiable factors such as performing logistic roles on deployment (aOR (95% CI) 1.13 (1.01 to 1.27)), dissatisfaction with work experience on deployment such as working with colleagues who did not do what was expected of them (aOR (95% CI) 4.09 (3.61 to 4.64)), and major problems at home while deployed (aOR (95% CI) 1.50 (1.38 to 1.63)) were also associated with reporting low unit cohesion. This is the first study to identify demographic, military service and deployment factors associated with low unit cohesion. The modifiable nature of unit cohesion means that military leaders could use this information to identify subgroups for targeted resilience interventions that may reduce vulnerabilities to mental health problems and improve the job satisfaction, preparedness and deployment experiences of serving members. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/
Force Transmission Modes of Non-Cohesive and Cohesive Materials at the Critical State.
Wang, Ji-Peng
2017-08-31
This paper investigates the force transmission modes, mainly described by probability density distributions, in non-cohesive dry and cohesive wet granular materials by discrete element modeling. The critical state force transmission patterns are focused on with the contact model effect being analyzed. By shearing relatively dense and loose dry specimens to the critical state in the conventional triaxial loading path, it is observed that there is a unique critical state force transmission mode. There is a universe critical state force distribution pattern for both the normal contact forces and tangential contact forces. Furthermore, it is found that using either the linear Hooke or the non-linear Hertz model does not affect the universe force transmission mode, and it is only related to the grain size distribution. Wet granular materials are also simulated by incorporating a water bridge model. Dense and loose wet granular materials are tested, and the critical state behavior for the wet material is also observed. The critical state strength and void ratio of wet granular materials are higher than those of a non-cohesive material. The critical state inter-particle distribution is altered from that of a non-cohesive material with higher probability in relatively weak forces. Grains in non-cohesive materials are under compressive stresses, and their principal directions are mainly in the axial loading direction. However, for cohesive wet granular materials, some particles are in tension, and the tensile stresses are in the horizontal direction on which the confinement is applied. The additional confinement by the tensile stress explains the macro strength and dilatancy increase in wet samples.
Denney, Justin T; Kimbro, Rachel Tolbert; Heck, Katherine; Cubbin, Catherine
2017-02-01
Objectives Food insecurity in the United States is a stubborn public health issue, affecting more than one in five households with children and disproportionately impacting racial and ethnic minority women and their children. Past research and policy has focused on household predictors of food insecurity, but neglected broader factors, such as perceived neighborhood social cohesion, that might protect those most vulnerable to food insecurity. Methods We use a racially and ethnically diverse data set from the Geographic Research on Wellbeing study (N = 2847) of women and their young children in California to investigate whether social cohesion influences food insecurity and whether it moderates the relationship between race/ethnicity and food insecurity. Results We find that lower levels of perceived residential neighborhood social cohesion associate with higher odds of food insecurity even after considering important household socioeconomic factors. In addition, our results suggest that social cohesion is most relevant for reducing the risk of food insecurity among racial and ethnic minority mothers. For example, the probability of food insecurity for immigrant Latina mothers is nearly 0.40 in neighborhoods where mothers perceive little to no cohesion and less than 0.10 in neighborhoods where mothers perceive high cohesion. Conclusions for Practice Higher levels of neighborhood perceived social cohesion are protective against food insecurity in households with children and especially so for racial and ethnic minority households who are at a heightened risk of food insecurity. Supporting programs that focus on building closer knit communities may be a key to reducing food insecurity overall and for reducing disparities in food insecurity by race and ethnicity.
Saleem, Farzana T; English, Devin; Busby, Danielle R; Lambert, Sharon F; Harrison, Aubrey; Stock, Michelle L; Gibbons, Frederick X
2016-07-01
Parental racial socialization is a parenting tool used to prepare African American adolescents for managing racial stressors. While it is known that parents' racial discrimination experiences affect the racial socialization messages they provide, little is known about the influence of factors that promote supportive and communal parenting, such as perceived neighborhood cohesion. In cohesive neighborhoods, neighbors may help parents address racial discrimination by monitoring youth and conveying racial socialization messages; additionally, the effect of neighborhood cohesion on parents' racial socialization may differ for boys and girls because parents socialize adolescents about race differently based on expected encounters with racial discrimination. Therefore, the current study examines how parents' perception of neighborhood cohesion and adolescents' gender moderate associations between parents' racial discrimination experiences and the racial socialization messages they deliver to their adolescents. Participants were a community sample of 608 African American adolescents (54 % girls; mean age = 15.5) and their primary caregivers (86 % biological mothers; mean age = 42.0). Structural equation modeling indicated that parental racial discrimination was associated with more promotion of mistrust messages for boys and girls in communities with low neighborhood cohesion. In addition, parental racial discrimination was associated with more cultural socialization messages about racial pride and history for boys in neighborhoods with low neighborhood cohesion. The findings suggest that parents' racial socialization messages are influenced by their own racial discrimination experiences and the cohesiveness of the neighborhood; furthermore, the content of parental messages delivered varies based on adolescents' gender.
Force Transmission Modes of Non-Cohesive and Cohesive Materials at the Critical State
2017-01-01
This paper investigates the force transmission modes, mainly described by probability density distributions, in non-cohesive dry and cohesive wet granular materials by discrete element modeling. The critical state force transmission patterns are focused on with the contact model effect being analyzed. By shearing relatively dense and loose dry specimens to the critical state in the conventional triaxial loading path, it is observed that there is a unique critical state force transmission mode. There is a universe critical state force distribution pattern for both the normal contact forces and tangential contact forces. Furthermore, it is found that using either the linear Hooke or the non-linear Hertz model does not affect the universe force transmission mode, and it is only related to the grain size distribution. Wet granular materials are also simulated by incorporating a water bridge model. Dense and loose wet granular materials are tested, and the critical state behavior for the wet material is also observed. The critical state strength and void ratio of wet granular materials are higher than those of a non-cohesive material. The critical state inter-particle distribution is altered from that of a non-cohesive material with higher probability in relatively weak forces. Grains in non-cohesive materials are under compressive stresses, and their principal directions are mainly in the axial loading direction. However, for cohesive wet granular materials, some particles are in tension, and the tensile stresses are in the horizontal direction on which the confinement is applied. The additional confinement by the tensile stress explains the macro strength and dilatancy increase in wet samples. PMID:28858238
Validating Experimental Bedform Dynamics on Cohesive Sand-Mud Beds in the Dee Estuary
NASA Astrophysics Data System (ADS)
Baas, Jaco H.; Baker, Megan; Hope, Julie; Malarkey, Jonathan; Rocha, Renata
2014-05-01
Recent laboratory experiments and field measurements have shown that small quantities of cohesive clay, and in particular 'sticky' biological polymers, within a sandy substrate dramatically reduce the development rate of sedimentary bedforms, with major implications for sediment transport rate calculations and process interpretations from the sedimentary record. FURTHER INFORMATION Flow and sediment transport predictions from sedimentary structures found in modern estuaries and within estuarine geological systems are impeded by an almost complete lack of process-based knowledge of the behaviour of natural sediments that consist of mixtures of cohesionless sand and biologically-active cohesive mud. Indeed, existing predictive models are largely based on non-organic cohesionless sands, despite the fact that mud, in pure form or mixed with sand, is the most common sediment on Earth and also the most biologically active interface across a range of Earth-surface environments, including rivers and shallow seas. The multidisciplinary COHBED project uses state-of-the-art laboratory and field technologies to measure the erosional properties of mixed cohesive sediment beds and the formation and stability of sedimentary bedforms on these beds, integrating the key physical and biological processes that govern bed evolution. The development of current ripples on cohesive mixed sediment beds was investigated as a function of physical control on bed cohesion versus biological control on bed cohesion. These investigations included laboratory flume experiments in the Hydrodynamics Laboratory (Bangor University) and field experiments in the Dee estuary (at West Kirby near Liverpool). The flume experiments showed that winnowing of fine-grained cohesive sediment, including biological stabilisers, is an important process affecting the development rate, size and shape of the cohesive bedforms. The ripples developed progressively slower as the kaolin clay fraction in the sandy substrate bed was increased. The same result was obtained for xanthan gum, which is a proxy for biological polymers produced by microphytobenthos. Yet, the xanthan gum was several orders more effective in slowing down ripple development than kaolin clay, suggesting that the cohesive forces for biological polymers are much higher than for clay minerals, and that sedimentological process models should refocus on biostabilisation processes. The first results of the field experiments show that the winnowing of fines from developing ripples and the slowing down of current ripple development in mixed cohesive sediment is mimicked on intertidal flats in the Dee estuary. In particular, these field data revealed that current ripples in cohesive sediment are smaller with more two-dimensional crestlines than in non-cohesive sand. The wider implications of these findings will be discussed. COHBED Project Team (NERC): Alan Davies (Bangor University); Daniel Parsons, Leiping Ye (University of Hull); Jeffrey Peakall (University of Leeds); Dougal Lichtman, Louise O'Boyle, Peter Thorne (NOC Liverpool); Sarah Bass, Andrew Manning, Robert Schindler (University of Plymouth); Rebecca Aspden, Emma Defew, Julie Hope, David Paterson (University of St Andrews)
ERIC Educational Resources Information Center
Pagani, Camilla
2014-01-01
The issue of diversity, in its broadest sense, is discussed here in its relation to social cohesion, cross-cultural relations, ingroup-outgroup relations and educational interventions. The main thesis of the paper is that real social cohesion in an ingroup rests on the acknowledgment of and the dialog with the diversities of the members of the…
Cohesion and Trauma: An Examination of a Collegiate Women's Volleyball Team
ERIC Educational Resources Information Center
Fletcher, Teresa B.; Meyer, Barbara B.
2009-01-01
This study examined the effects of Adventure Based Counseling (i.e., a low-element challenge program) on the cohesion of a collegiate women's volleyball team. Results suggest postintervention improvements in team cohesion. The support created in the challenge experience also transferred to the players helping one another to grieve the untimely…
Group Cohesion DEOCS 4.1 Construct Validity Summary
2017-08-01
Group Cohesion DEOCS 4.1 Construct Validity Summary DEFENSE EQUAL OPPORTUNITY MANAGEMENT INSTITUTE DIRECTORATE...See Table 4 for more information regarding item reliabilities. The relationship between the original four-point scale (Organizational Cohesion) and...future analyses, including those using the seven-point scale. Tables 4 and 5 provide additional information regarding the reliability and descriptive
Supporting Students' Learning in the Domain of Computer Science
ERIC Educational Resources Information Center
Gasparinatou, Alexandra; Grigoriadou, Maria
2011-01-01
Previous studies have shown that students with low knowledge understand and learn better from more cohesive texts, whereas high-knowledge students have been shown to learn better from texts of lower cohesion. This study examines whether high-knowledge readers in computer science benefit from a text of low cohesion. Undergraduate students (n = 65)…
ERIC Educational Resources Information Center
Schneider, W. Joel; Roman, Zachary
2018-01-01
We used data simulations to test whether composites consisting of cohesive subtest scores are more accurate than composites consisting of divergent subtest scores. We demonstrate that when multivariate normality holds, divergent and cohesive scores are equally accurate. Furthermore, excluding divergent scores results in biased estimates of…
ERIC Educational Resources Information Center
Lam, Brian Trung
2005-01-01
This prospective study examined whether interdependent self-construal (collectivism), independent self-construal (individualism), family cohesion, and social support would predict levels of self-esteem among Vietnamese American adolescents. Standardized self-report measures of family cohesion, social support, and self-esteem, as well as a measure…
Effects of Lexical Cohesion and Macrorules on EFL Students' Main Idea Comprehension
ERIC Educational Resources Information Center
Wilawan, Sujunya
2011-01-01
This study investigated the effects of an instructional procedure which incorporated lexical cohesion and macrorules to promote main idea comprehension of Thai EFL students. One hundred and six undergraduate students taking a reading module were randomly assigned to one of three teaching conditions: the combined use of lexical cohesion and…
DOT National Transportation Integrated Search
1999-12-01
The effects of cohesion on pier scour was investigated experimentally using four-foot-wide, eight-foot-wide, and twenty-foot-wide test flumes at the Engineering Research Center, Colorado State University. In the first part of the experiments, clay-sa...
Argento, Elena; Duff, Putu; Bingham, Brittany; Chapman, Jules; Nguyen, Paul; Strathdee, Steffanie A; Shannon, Kate
2016-06-01
Community empowerment can be a powerful determinant of HIV risk among sex workers (SWs). This study modeled the impact of social cohesion on client condom refusal among SWs in Vancouver. Longitudinal data were drawn from a prospective cohort of SWs (2010-2013). Lippman and colleagues' Social Cohesion Scale measured SWs' connectedness (i.e., perception of mutual aid, trust, support). Multivariable logistic regression examined the independent effect of social cohesion on client condom refusal. Of 654 SWs, 22 % reported baseline client condom refusal and 34 % over 3 years. The baseline median social cohesion score was 24 (IQR 20-29, range 4-45). In the final confounding model, for every one-point increase in the social cohesion score, average odds of condom refusal decreased by 3 % (AOR 0.97; 95 % CI 0.95-0.99). Community empowerment can have a direct protective effect on HIV risk. These findings highlight the need for a legal framework that enables collectivization and SW-led efforts in the HIV response.
The impact of trait emotional intelligence on nursing team performance and cohesiveness.
Quoidbach, Jordi; Hansenne, Michel
2009-01-01
Claims about the positive influence of emotional intelligence (EI) on work team performance are very numerous, both in commercial and scientific literature. However, despite the huge interest that media and business consultants put in EI and its fast-growing use in organizations, there is very little empirical evidence to support these claims. In this study, we investigated the relationships between EI, performance, and cohesiveness in 23 nursing teams. EI was assessed using the modified version of the Schutte Emotional Intelligence Scale and cohesiveness with the Group Cohesiveness Scale. Finally, nursing team performance was measured at four different levels: job satisfaction, chief nursing executives' rating, turnover rate, and health care quality. Results showed that health care quality was positively correlated with emotion regulation. Emotion regulation was also positively correlated with group cohesiveness. Surprisingly, it also appears that emotion appraisal was negatively correlated with the health care quality provided by teams. These results suggest that EI and, more specifically, Emotional Regulation may provide an interesting new way of enhancing nursing teams' cohesion and patient/client outcomes.
Crespo, Carla; Canavarro, M. Cristina; Kazak, Anne E.
2015-01-01
Objective Family rituals are associated with adaptive functioning in pediatric illness, including quality of life (QoL). This article explores the role of family cohesion and hope as mediators of this association in children with cancer and their parents. Methods Portuguese children with cancer (N = 389), on- and off-treatment, and one of their parents completed self-report measures. Structural equation modeling was used to examine direct and indirect links between family rituals and QoL. Results When children and parents reported higher levels of family rituals, they also reported more family cohesion and hope, which were linked to better QoL. At the dyadic level, children’s QoL was related to parents’ family rituals through the child’s family cohesion. This model was valid across child’s age-group, treatment status, and socioeconomic status. Conclusions Family rituals are important in promoting QoL in pediatric cancer via family cohesion and hope individually and via family cohesion in terms of parent–child interactions. PMID:25775914
A test of the social cohesion hypothesis: interactive female marmots remain at home.
Blumstein, Daniel T; Wey, Tina W; Tang, Karisa
2009-08-22
Individuals frequently leave home before reaching reproductive age, but the proximate causes of natal dispersal remain relatively unknown. The social cohesion hypothesis predicts that individuals who engage in more (affiliative) interactions are less likely to disperse. Despite the intuitive nature of this hypothesis, support is both limited and equivocal. We used formal social network analyses to quantify precisely both direct and indirect measures of social cohesion in yellow-bellied marmots. Because approximately 50 per cent of female yearlings disperse, we expected that social relationships and network measures of cohesion would predict dispersal. By contrast, because most male yearlings disperse, we expected that social relationships and cohesion would play a less important role. We found that female yearlings that interacted with more individuals, and those that were more socially embedded in their groups, were less likely to disperse. For males, social interactions were relatively unimportant determinants of dispersal. This is the first strong support for the social cohesion hypothesis and suggests that the specific nature of social relationships, not simply the number of affiliative relationships, may influence the propensity to disperse.
A test of the social cohesion hypothesis: interactive female marmots remain at home
Blumstein, Daniel T.; Wey, Tina W.; Tang, Karisa
2009-01-01
Individuals frequently leave home before reaching reproductive age, but the proximate causes of natal dispersal remain relatively unknown. The social cohesion hypothesis predicts that individuals who engage in more (affiliative) interactions are less likely to disperse. Despite the intuitive nature of this hypothesis, support is both limited and equivocal. We used formal social network analyses to quantify precisely both direct and indirect measures of social cohesion in yellow-bellied marmots. Because approximately 50 per cent of female yearlings disperse, we expected that social relationships and network measures of cohesion would predict dispersal. By contrast, because most male yearlings disperse, we expected that social relationships and cohesion would play a less important role. We found that female yearlings that interacted with more individuals, and those that were more socially embedded in their groups, were less likely to disperse. For males, social interactions were relatively unimportant determinants of dispersal. This is the first strong support for the social cohesion hypothesis and suggests that the specific nature of social relationships, not simply the number of affiliative relationships, may influence the propensity to disperse. PMID:19493901
Argento, Elena; Duff, Putu; Bingham, Brittany; Chapman, Jules; Nguyen, Paul; Strathdee, Steffanie A.
2015-01-01
Community empowerment can be a powerful determinant of HIV risk among sex workers (SWs). This study modeled the impact of social cohesion on client condom refusal among SWs in Vancouver. Longitudinal data were drawn from a prospective cohort of SWs (2010–2013). Lippman and colleagues’ Social Cohesion Scale measured SWs’ connectedness (i.e., perception of mutual aid, trust, support). Multivariable logistic regression examined the independent effect of social cohesion on client condom refusal. Of 654 SWs, 22 % reported baseline client condom refusal and 34 % over 3 years. The baseline median social cohesion score was 24 (IQR 20–29, range 4–45). In the final confounding model, for every one-point increase in the social cohesion score, average odds of condom refusal decreased by 3 % (AOR 0.97; 95 % CI 0.95–0.99). Community empowerment can have a direct protective effect on HIV risk. These findings highlight the need for a legal framework that enables collectivization and SW-led efforts in the HIV response. PMID:26499335
Joh, Ju Youn; Kim, Sun; Park, Jun Li; Kim, Yeon Pyo
2013-05-01
The Family Adaptability and Cohesion Evaluation Scale (FACES) III using the circumplex model has been widely used in investigating family function. However, the criticism of the curvilinear hypothesis of the circumplex model has always been from an empirical point of view. This study examined the relationship between adolescent adaptability, cohesion, and adolescent problem behaviors, and especially testing the consistency of the curvilinear hypotheses with FACES III. We used the data from 398 adolescent participants who were in middle school. A self-reported questionnaire was used to evaluate the FACES III and Youth Self Report. According to the level of family adaptability, significant differences were evident in internalizing problems (P = 0.014). But, in externalizing problems, the results were not significant (P = 0.305). Also, according to the level of family cohesion, significant differences were in internalizing problems (P = 0.002) and externalizing problems (P = 0.004). The relationship between the dimensions of adaptability, cohesion and adolescent problem behaviors was not curvilinear. In other words, adolescents with high adaptability and high cohesion showed low problem behaviors.
Joh, Ju Youn; Kim, Sun; Park, Jun Li
2013-01-01
Background The Family Adaptability and Cohesion Evaluation Scale (FACES) III using the circumplex model has been widely used in investigating family function. However, the criticism of the curvilinear hypothesis of the circumplex model has always been from an empirical point of view. This study examined the relationship between adolescent adaptability, cohesion, and adolescent problem behaviors, and especially testing the consistency of the curvilinear hypotheses with FACES III. Methods We used the data from 398 adolescent participants who were in middle school. A self-reported questionnaire was used to evaluate the FACES III and Youth Self Report. Results According to the level of family adaptability, significant differences were evident in internalizing problems (P = 0.014). But, in externalizing problems, the results were not significant (P = 0.305). Also, according to the level of family cohesion, significant differences were in internalizing problems (P = 0.002) and externalizing problems (P = 0.004). Conclusion The relationship between the dimensions of adaptability, cohesion and adolescent problem behaviors was not curvilinear. In other words, adolescents with high adaptability and high cohesion showed low problem behaviors. PMID:23730484
SA1 and TRF1 synergistically bind to telomeric DNA and promote DNA-DNA pairing
NASA Astrophysics Data System (ADS)
Wang, Hong; Lin, Jiangguo; Countryman, Preston; Pan, Hai; Parminder Kaur Team; Robert Riehn Team; Patricia Opresko Team; Jane Tao Team; Susan Smith Team
Impaired telomere cohesion leads to increased aneuploidy and early onset of tumorigenesis. Cohesion is thought to occur through the entrapment of two DNA strands within tripartite cohesin ring(s), along with a fourth subunit (SA1/SA2). Surprisingly, cohesion rings are not essential for telomere cohesion, which instead requires SA1 and shelterin proteins including TRF1. However, neither this unique cohesion mechanism at telomeres or DNA-binding properties of SA1 is understood. Here, using single-molecule fluorescence imaging of quantum dot-labeled proteins on DNA we discover that while SA1 diffuses across multiple telomeric and non-telomeric regions, the diffusion mediated through its N-terminal domain is slower at telomeric regions. However, addition of TRF1 traps SA1 within telomeric regions, which form longer DNA-DNA pairing tracts than with TRF1 alone, as revealed by atomic force microscopy. Together, these experimental results and coarse-grained molecular dynamics simulations suggest that TRF1 and SA1 synergistically interact with DNA to support telomere cohesion without cohesin rings.
NASA Astrophysics Data System (ADS)
Nanson, G. C.; Young, R. W.
1981-07-01
Although most streams show a downstream increase in channel size corresponding to a downstream increase in flood discharges, those flowing off the Illawarra escarpment of New South Wales show a marked reduction of channel size, accompanied by a down-stream increase in flood frequency in their lower reaches. Within the confined and steeply sloping valleys of the escarpment foothills, bed and bank sediments are relatively coarse and uncohesive, and channels increase in size, corresponding to increasing discharge downstream. However, once these streams emerge into more open rural valleys at lower slopes and are accompanied by extensive floodplains formed of fine cohesive sediment, there is a dramatic reduction in channel size. This decrease in channel size apparently results from a sudden decline in channel slope and associated stream power, the cohesive nature of downstream alluvium, its retention on the channel banks by a dense cover of pasture grasses, and the availability of an extensive floodplain to carry displaced floodwater. Under these conditions floodwaters very frequently spill out over the floodplain and the downstream channel-flow becomes a relatively unimportant component of the total peak discharge. This emphasizes the importance of these floodplains as a part of the total channel system. In situations where urban development has increased peak runoff and reduced the available area of effective floodplain, stream channels formed in this fine alluvium rapidly entrench and increase in cross-sectional area by 2-3 times. Minor man-induced channel alteration and maintenance appears to trigger this enlargement.
Ruijsbroek, Annemarie; Droomers, Mariël; Hardyns, Wim; Groenewegen, Peter P; Stronks, Karien
2016-05-01
This study examined how the health of Dutch residents in 2012 was influenced by changes in neighbourhood social cohesion, disorder, and unsafety feelings between 2009 and 2011. Multilevel regression analyses on repeated cross-sectional survey data included 43,635 respondents living in 2100 areas. Deteriorating social cohesion and unsafety feelings were negatively associated with general health, while improvement in social cohesion was associated with better general health of the population. When the interplay of neighbourhood features was considered, deteriorating neighbourhood safety appeared decisive for health, i.e. improving social cohesion did not mitigate the health effect of deteriorating neighbourhood safety. Our results show it is important to take concurrent interactions between neighbourhood features into account when examining their health impact. Copyright © 2016 Elsevier Ltd. All rights reserved.
Fast determination of structurally cohesive subgroups in large networks
Sinkovits, Robert S.; Moody, James; Oztan, B. Tolga; White, Douglas R.
2016-01-01
Structurally cohesive subgroups are a powerful and mathematically rigorous way to characterize network robustness. Their strength lies in the ability to detect strong connections among vertices that not only have no neighbors in common, but that may be distantly separated in the graph. Unfortunately, identifying cohesive subgroups is a computationally intensive problem, which has limited empirical assessments of cohesion to relatively small graphs of at most a few thousand vertices. We describe here an approach that exploits the properties of cliques, k-cores and vertex separators to iteratively reduce the complexity of the graph to the point where standard algorithms can be used to complete the analysis. As a proof of principle, we apply our method to the cohesion analysis of a 29,462-vertex biconnected component extracted from a 128,151-vertex co-authorship data set. PMID:28503215
Caicedo-Carvajal, Carlos E.; Shinbrot, Troy; Foty, Ramsey A.
2010-01-01
Background Tissue organization during embryonic development and wound healing depends on the ability of cells on the one hand to exchange adhesive bonds during active rearrangement and on the other to become fixed in place as tissue homeostasis is reached. Cells achieve these contradictory tasks by regulating either cell-cell adhesive bonds, mediated by cadherins, or cell-extracellular matrix (ECM) connections, regulated by integrins. Integrin α5β1 and soluble fibronectin (sFN) are key players in cell-ECM force generation and in ECM polymerization. Here, we explore the interplay between integrin α5β1 and sFN and its influence on tissue mechanical properties and cell sorting behavior. Methodology/Principal Findings We generated a series of cell lines varying in α5β1 receptor density. We then systematically explored the effects of different sFN concentrations on aggregate biomechanical properties using tissue surface tensiometry. We found previously unreported complex behaviors including the observation that interactions between fibronectin and integrin α5β1 generates biphasic tissue cohesion profiles. Specifically, we show that at constant sFn concentration, aggregate cohesion increases linearly as α5β1 receptor density is increased from low to moderate levels, producing a transition from viscoelastic-liquid to pseudo viscoelastic-solid behavior. However, further increase in receptor density causes an abrupt drop in tissue cohesion and a transition back to viscoelastic-liquid properties. We propose that this may be due to depletion of sFn below a critical value in the aggregate microenvironment at high α5β1 levels. We also show that differential expression of α5β1 integrin can promote phase-separation between cells. Conclusions/Significance The interplay between α5-integrin and sFn contributes significantly to tissue cohesion and, depending on their level of expression, can mediate a shift from liquid to elastic behavior. This interplay represents a tunable level of control between integrins and the ECM that can influence tissue cohesion and other mechanical properties, which may translate to the specification of tissue structure and function. These studies provide insights into important biological processes such as embryonic development, wound healing, and for tissue engineering applications. PMID:20686611
Measurement of Cohesion in Asteroid Regolith Materials
NASA Technical Reports Server (NTRS)
Kleinhenz, Julie; Gaier, James; Waters, Deborah; Harvey, Ralph; Zeszut, Zoe; Carreno, Brandon; Shober, Patrick
2017-01-01
There is increasing evidence that a large fraction of asteroids, and even Phobos, have such low densities (<2 g/cu cm) that the are unlikely to be consolidated rocks in space.-Water is unlikely due to close orbits to the sun. Instead, many of these asteroids are thought to be made up of unconsolidated smaller particles of varying size referred to as rubble piles. Images of the asteroid Itokawa reinforce this hypothesis. What holds the rubble piles together? Gravitational forces alone are not strong enough to hold together rubble pile asteroids, at least not those that are rapidly spinning Van der Waals forces and or Electrostatic forces must therefore be responsible for holding them together. Previous work suggests that electrostatic forces, which are orders of magnitude stronger are far more likely. Charge build-up is a likely consequence of the interaction of airless bodies with the solar wind plasma, analogous to what has been proposed to occur on the moon. Objective: Experimentally measure cohesive forces relevant to those holding rubble pile asteroids together
Density-wave fronts on the brink of wet granular condensation
NASA Astrophysics Data System (ADS)
Huang, Kai; Zippelius, Andreas; Sand lab @ University of Bayreuth Team
2017-11-01
From sand dunes to Faraday heaping, driven granular matter, i.e., large agglomeration of macroscopic particles, is rich pattern forming system. When a granular material is partially wet (e.g., wet sand on the beach), a different pattern forming scenario arises due to the cohesive particle-particle interactions. Here, we focus on the formation of density-wave fronts in an oscillated wet granular layer undergoing a gas-liquid-like transition. The threshold of the instability is governed by the amplitude of the vertical vibrations. Fronts, which are curved into a spiral shape, propagate coherently along the circular rim of the container with leading edges. They are stable beyond a critical distance from the container center. Based on the measurement of the critical distance and the rotation frequency, we propose a model for the pattern formation by considering the competition between the time scale for the collapse of cohesive particles and that of the energy injection resisting this process. Deutsche Forschungsgemeinschaft (Grant No. HU1939 4-1).
NASA Astrophysics Data System (ADS)
Kellogg, Kevin; Liu, Peiyuan; Lamarche, Casey; Hrenya, Christine
2017-11-01
In flows of cohesive particles, agglomerates will readily form and break. These agglomerates are expected to complicate how particles interact with the surrounding fluid in multiphase flows, and consequently how the solids flow. In this work, a dilute flow of particles driven by gas against gravity is studied. A continuum framework, composed of a population balance to predict the formation of agglomerates, and kinetic-theory-based balances, is used to predict the flow of particles. The closures utilized for the birth and death rates due to aggregation and breakage in the population balance take into account how the impact velocity (the granular temperature) affects the outcome of a collision as aggregation, rebound, or breakage. The agglomerate size distribution and solids velocity predicted by the continuum framework are compared to discrete element method (DEM) simulations, as well to experimental results of particles being entrained from the riser of a fluidized bed. Dow Corning Corporation.
Chiu, Chi-Kai; Ferreira, Joao; Luo, Tzy-Jiun M.; Geng, Haixia; Lin, Feng-Chang; Ko, Ching-Chang
2012-01-01
Hydroxyapatite-gelatin modified siloxane (GEMOSIL) nanocomposite was developed by coating, kneading and hardening processes to provide formable scaffolding for alloplastic graft applications. The present study aims to characterize scaffolding formability and mechanical properties of GEMOSIL, and to test the in vitro and in vivo biocompatibility of GEMOSIL. Buffer Solution initiated formable paste followed by the sol-gel reaction led to a final hardened composite. Results showed the adequate coating of aminosilane, 11–19 wt%, affected the cohesiveness of the powders and the final compressive strength (69 MPa) of the composite. TGA and TEM results showed the effective aminosilane coating that preserves hydroxyapatite-gelatin nanocrystals from damage. Both GEMOSIL with and without titania increased the mineralization of preosteoblasts in vitro. Only did titania additives revealed good in vivo bone formation in rat calvarium defects. The scaffolding formability, due to cohesive bonding among GEMOSIL particles, could be further refined to fulfill the complicated scaffold processes. PMID:22669282
Browne, Tess; Hull, Lisa; Horn, Oded; Jones, Margaret; Murphy, Dominic; Fear, Nicola T; Greenberg, Neil; French, Claire; Rona, Roberto J; Wessely, Simon; Hotopf, Matthew
2007-06-01
Deployment to the 2003 Iraq War was associated with ill health in reserve armed forces personnel. To investigate reasons for the excess of ill health in reservists. UK personnel who were deployed to the 2003 Iraq War completed a health survey about experiences on deployment to Iraq. Health status was measured using self-report of common mental disorders, post-traumatic stress disorder (PTSD), fatigue, physical symptoms and well-being. Reservists were older and of higher rank than the regular forces. They reported higher exposure to traumatic experiences, lower unit cohesion, more problems adjusting to homecoming and lower marital satisfaction. Most health outcomes could be explained by role, experience of traumatic events or unit cohesion in theatre. PTSD symptoms were the one exception and were paradoxically most powerfully affected by differences in problems at home rather than events in Iraq. The increased ill-health of reservists appears to be due to experiences on deployment and difficulties with homecoming.
Fleischer, Nancy L; Lozano, Paula; Arillo Santillán, Edna; Reynales Shigematsu, Luz Myriam; Thrasher, James F
2015-11-01
Recent increases in violent crime may impact a variety of health outcomes in Mexico. We examined relationships between neighbourhood-level violence and smoking behaviours in a cohort of Mexican smokers from 2011 to 2012, and whether neighbourhood-level social cohesion modified these relationships. Data were analysed from adult smokers and recent ex-smokers who participated in waves 5 and 6 of the International Tobacco Control Mexico survey. Self-reported neighbourhood violence and social cohesion were asked of wave 6 survey participants (n=2129 current and former smokers, n=150 neighbourhoods). Neighbourhood-level averages for violence and social cohesion (ranges 4-14 and 10-25, respectively) were assigned to individuals. We used generalised estimating equations to determine associations between neighbourhood indicators and individual-level smoking intensity, quit behaviours and relapse. Higher neighbourhood violence was associated with higher smoking intensity (risk ratio (RR)=1.17, 95% CI 1.02 to 1.33), and fewer quit attempts (RR=0.72, 95% CI 0.61 to 0.85). Neighbourhood violence was not associated with successful quitting or relapse. Higher neighbourhood social cohesion was associated with more quit attempts and more successful quitting. Neighbourhood social cohesion modified the association between neighbourhood violence and smoking intensity: in neighbourhoods with higher social cohesion, as violence increased, smoking intensity decreased and in neighbourhoods with lower social cohesion, as violence increased, so did smoking intensity. In the context of recent increased violence in Mexico, smokers living in neighbourhoods with more violence may smoke more cigarettes per day and make fewer quit attempts than their counterparts in less violent neighbourhoods. Neighbourhood social cohesion may buffer the impact of violence on smoking intensity. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.
Liu, Liang; Liu, Cuilian; Zhao, Xudong
2017-02-25
Between 22% and 58% of patients in primary care settings complain of somatic symptoms. Previous research has found that somatization was associated with anger traits and family functions. However, studies that specifically assess the moderating effect of family function in how anger traits become somatic complaints are lacking. This study was designed to examine whether the variances in family cohesion and family adaptability moderated the strength of the relationship between anger traits and somatization. A cross-section design was conducted and 2008 college students were recruited from a comprehensive university in Shanghai. All participants finished questionnaires including Symptom Check List- 90 (SCL-90), State-Trait Anger Expression Inventory 2 (STAXI-2, Chinese version) and Family Adaptability and Cohesion Scale, second edition (FACES II, Chinese Version) to assess their degree of current somatization, anger trait and family function. Hierarchical linear regression analysis (Enter) was conducted respectively for men and women to examine the moderation effect of family cohesion and family adaptability in the association between anger and somatization. Somatic symptoms were significantly linked in the expected directions with depression and anger trait for both genders. Family cohesion and family adaptability were negatively associated with somatic symptoms. For female college students family cohesion was found to moderate the link between anger trait and somatization, but for male college students the moderation effect of family cohesion was marginally significant. The moderating role of family adaptability was significant for neither male nor female after current depressive symptoms were accounted for. Proneness to anger is an independent predictor of somatization. For women, a high level of family cohesion was a protective factor which could reduce the influence of anger trait on somatic symptoms. Without comorbidity of current depression, family adaptability to some degree exempted individuals with anger proneness from developing somatic complaints. Interventions that integrate family cohesion cultivation, family flexibility fostering and depression treatment might be more effective for somatic patients high in anger trait.
Gallagher, Meagan E; Tasca, Giorgio A; Ritchie, Kerri; Balfour, Louise; Maxwell, Hilary; Bissada, Hany
2014-03-01
Yalom and Leszcz (2005) indicated that interpersonal learning is a key therapeutic factor in group psychotherapy. In this study, we conceptualized interpersonal learning as the convergence over time between an individual's and the group's perception of the individual's cohesion to the group. First, we developed parallel measures of: (a) an individual's self-rated cohesion to the group (Cohesion Questionnaire-Individual Version [CQ-I]), and (b) the group's rating of the individual's cohesion to the group (CQ-G) based on the original Cohesion Questionnaire (CQ; Piper, Marache, Lacroix, Richardsen, & Jones, 1983). Second, we used these parallel scales to assess differences between an individual's self-rating and the mean of the group's ratings of the individual's cohesion to the group. Women with binge eating disorder (N = 102) received Group Psychodynamic Interpersonal Psychotherapy. Participants were assigned to homogeneously composed groups of either high or low attachment anxiety. Outcomes were measured pre- and post-treatment, and the CQ-I and CQ-G were administered every fourth group session. We found significant convergence over time between the CQ-I and mean CQ-G scale scores in both attachment anxiety conditions. Participants with higher attachment anxiety had lower individual self-ratings of cohesion and had greater discrepancies between the CQ-I and CG-G compared with those with lower attachment anxiety. There was a significant relationship between greater convergence in cohesion ratings and improved self-esteem at post-treatment. More accurate self-perceptions through feedback from group members may be a key factor in facilitating increased self-esteem in group therapy. Group therapists may facilitate such interpersonal learning, especially for those higher in attachment anxiety, by noting discrepancies and then encouraging convergence between an individual and the group in their perceptions of cohesion to the group. (c) 2014 APA, all rights reserved.
Gesell, Sabina B.; Barkin, Shari L.; Sommer, Evan C.; Thompson, Jessica R.; Valente, Thomas W.
2016-01-01
Objective Many behavior change programs are delivered in group settings to manage implementation costs and to foster support and interactions among group members to facilitate behavior change. Understanding the group dynamics that evolve in group settings (e.g., weight management, Alcoholics Anonymous) is important, yet rarely measured. This paper examined the relationship between social network ties and group cohesion in a group-based intervention to prevent obesity in children. Method The data reported are process measures from an ongoing community-based randomized controlled trial. 305 parents with a child (3-6 years) at risk of developing obesity were assigned to an intervention that taught parents healthy lifestyles. Parents met weekly for 12 weeks in small consistent groups. Two measures were collected at weeks 3 and 6: a social network survey (people in the group with whom one discusses healthy lifestyles); and the validated Perceived Cohesion Scale (Bollen & Hoyle, 1990). We used lagged random and fixed effects regression models to analyze the data. Results Cohesion increased from 6.51 to 6.71 (t=4.4, p<0.01). Network nominations tended to increase over the 3-week period in each network. In the combined discussion and advice network, the number of nominations increased from 1.76 to 1.95 (z=2.59, p<0.01). Cohesion at week 3 was the strongest predictor of cohesion at week 6 (b=0.55, p<0.01). Number of new network nominations at week 6 was positively related to cohesion at week 6 (b=0.06, p<.01). In sum, being able to name new network contacts was associated with feelings of cohesion. Conclusion This is the first study to demonstrate how network changes affect perceived group cohesion within a behavioral intervention. Given that many behavioral interventions occur in group settings, intentionally building new social networks could be promising to augment desired outcomes. PMID:26286298
Increases in Network Ties Are Associated With Increased Cohesion Among Intervention Participants.
Gesell, Sabina B; Barkin, Shari L; Sommer, Evan C; Thompson, Jessica R; Valente, Thomas W
2016-04-01
Many behavior change programs are delivered in group settings to manage implementation costs and to foster support and interactions among group members in order to facilitate behavior change. Understanding the group dynamics that evolve in group settings (e.g., weight management, Alcoholics Anonymous) is important, yet rarely measured. This article examined the relationship between social network ties and group cohesion in a group-based intervention to prevent obesity in children. The data reported are process measures from an ongoing community-based randomized controlled trial. A total of 305 parents with a child (3-6 years) at risk of developing obesity were assigned to an intervention that taught parents healthy lifestyles. Parents met weekly for 12 weeks in small consistent groups. Two measures were collected at Weeks 3 and 6: a social network survey (people in the group with whom one discusses healthy lifestyles) and the validated Perceived Cohesion Scale. We used lagged random and fixed effects regression models to analyze the data. Cohesion increased from 6.51 to 6.71 (t= 4.4,p< .01). Network nominations tended to increase over the 3-week period in each network. In the combined discussion and advice network, the number of nominations increased from 1.76 to 1.95 (z= 2.59,p< .01). Cohesion at Week 3 was the strongest predictor of cohesion at Week 6 (b= 0.55,p< .01). Number of new network nominations at Week 6 was positively related to cohesion at Week 6 (b= 0.06,p< .01). In sum, being able to name new network contacts was associated with feelings of cohesion. This is the first study to demonstrate how network changes affect perceived group cohesion within a behavioral intervention. Given that many behavioral interventions occur in group settings, intentionally building new social networks could be promising to augment desired outcomes. © 2015 Society for Public Health Education.
Barossa Night: cohesion in the British Army officer corps.
Bury, Patrick
2017-06-01
Contrasting the classical explanation of military group cohesion as sustained by interpersonal bonds, recent scholars have highlighted the importance of ritualized communication, training and drills in explaining effective military performance in professional armies. While this has offered a welcome addition to the cohesion literature and a novel micro-sociological method of examining cohesion, its primary evidential base has been combat groups. Indeed, despite their prominent role in directing operations over the past decade, the British Army's officer corps has received relatively little attention from sociologists during this period. No attempt has been made to explain cohesion in the officer corps. Using a similar method to recent cohesion scholars, this paper seeks to address this imbalance by undertaking a micro-sociology of one ritual in particular: 'Barossa Night' in the Royal Irish Regiment. Firstly, it draws on the work of Durkheim to examine how cohesion amongst the officer corps is created and sustained through a dense array of practises during formal social rituals. It provides evidence that the use of rituals highlights that social solidarity is central to understanding officer cohesion. Secondly, following Hockey's work on how private soldiers negotiate order, the paper shows how this solidarity in the officer corps is based on a degree of negotiated order and the need to release organizational tensions inherent in a strictly hierarchical rank structure. It highlights how the awarding of gallantry medals can threaten this negotiated order and fuel deviancy. In examining this behaviour, the paper shows that even amongst an officer class traditionally viewed as the elite upholders of organizational discipline, the negotiation of rank and hierarchy can be fluid. How deviant behaviour is later accepted and normalized by senior officers indicates that negotiated order is as important to understanding cohesion in the British Army's officer corps as it is amongst private soldiers. © London School of Economics and Political Science 2016.
Barber, Sharrelle; Hickson, DeMarc A; Kawachi, Ichiro; Subramanian, S V; Earls, Felton
2016-03-01
Few studies have examined the joint impact of neighborhood disadvantage and low social cohesion on health. Moreover, no study has considered the joint impact of these factors on a cumulative disease risk profile among a large sample of African American adults. Using data from the Jackson Heart Study, we examined the extent to which social cohesion modifies the relationship between neighborhood disadvantage and cumulative biological risk (CBR)-a measure of accumulated risk across multiple physiological systems. Our analysis included 4408 African American women and men ages 21-85 residing in the Jackson, MS Metropolitan Area. We measured neighborhood disadvantage using a composite score of socioeconomic indicators from the 2000 US Census and social cohesion was assessed using a 5-item validated scale. Standardized z-scores of biomarkers representing cardiovascular, metabolic, inflammatory, and neuroendocrine systems were combined to create a CBR score. We used two-level linear regression models with random intercepts adjusting for socio-demographic and behavioral covariates in the analysis. A three-way interaction term was included to examine whether the relationship between neighborhood disadvantage and CBR differed by levels of social cohesion and gender. The interaction between neighborhood disadvantage, social cohesion and gender was statistically significant (p = 0.05) such that the association between living in a disadvantaged neighborhood and CBR was strongest for men living in neighborhoods with low levels of social cohesion (B = 0.63, SE: 0.32). In gender-specific models, we found a statistically significant interaction between neighborhood disadvantage and social cohesion for men (p = 0.05) but not for women (p = 0.50). Neighborhoods characterized by high levels of economic disadvantage and low levels of social cohesion contribute to higher cumulative risk of disease among African American men. This suggests that they may face a unique set of challenges that put them at greater risk in these settings. Copyright © 2016 Elsevier Ltd. All rights reserved.
Barber, Sharrelle; Hickson, DeMarc A.; Kawachi, Ichiro; Subramanian, S.V.; Earls, Felton
2016-01-01
Objectives Few studies have examined the joint impact of neighborhood disadvantage and low social cohesion on health. Moreover, no study has considered the joint impact of these factors on a cumulative disease risk profile among a large sample of African American adults. Using data from the Jackson Heart Study, we examined the extent to which social cohesion modifies the relationship between neighborhood disadvantage and cumulative biological risk (CBR)—a measure of accumulated risk across multiple physiological systems. Methods Our analysis included 4,408 African American women and men ages 21–85 residing in the Jackson, MS Metropolitan Area. We measured neighborhood disadvantage using a composite score of socioeconomic indicators from the 2000 US Census and social cohesion was assessed using a 5-item validated scale. Standardized z-scores of biomarkers representing cardiovascular, metabolic, inflammatory, and neuroendocrine systems were combined to create a CBR score. We used two-level linear regression models with random intercepts adjusting for socio-demographic and behavioral covariates in the analysis. A three-way interaction term was included to examine whether the relationship between neighborhood disadvantage and CBR differed by levels of social cohesion and gender. Results The interaction between neighborhood disadvantage, social cohesion and gender was statistically significant (p=0.05) such that the association between living in a disadvantaged neighborhood and CBR was strongest for men living in neighborhoods with low levels of social cohesion (B=0.63, SE: 0.32). In gender-specific models, we found a statistically significant interaction between neighborhood disadvantage and social cohesion for men (p=0.05) but not for women (p=0.50). Conclusion Neighborhoods characterized by high levels of economic disadvantage and low levels of social cohesion contribute to higher cumulative risk of disease among African American men. This suggests that they may face a unique set of challenges that put them at greater risk in these settings. PMID:26894941
Discrete Element Method Simulation of a Boulder Extraction From an Asteroid
NASA Technical Reports Server (NTRS)
Kulchitsky, Anton K.; Johnson, Jerome B.; Reeves, David M.; Wilkinson, Allen
2014-01-01
The force required to pull 7t and 40t polyhedral boulders from the surface of an asteroid is simulated using the discrete element method considering the effects of microgravity, regolith cohesion and boulder acceleration. The connection between particle surface energy and regolith cohesion is estimated by simulating a cohesion sample tearing test. An optimal constant acceleration is found where the peak net force from inertia and cohesion is a minimum. Peak pulling forces can be further reduced by using linear and quadratic acceleration functions with up to a 40% reduction in force for quadratic acceleration.
Comprehension of Health-related Written Materials by Older Adults
Liu, Chiung-ju; Kemper, Susan; Bovaird, James A.
2008-01-01
This study examined how Flesch Reading Ease and text cohesion affect older adults' comprehension of common health texts. All older adults benefited when high Flesh Reading Ease was combined with high cohesion. Older adults with small working memories had more difficulty understanding texts high in Flesch Reading Ease. Additionally, older adults with low verbal ability or older than 77 years of age had difficulty understanding texts high in text cohesion but low in Flesch Reading Ease. These results imply that writers must increase Flesch Reading Ease without disrupting text cohesion to ensure comprehension of health-related texts. PMID:19543546
The effect of coarse gravel on cohesive sediment entrapment in an annular flume
NASA Astrophysics Data System (ADS)
Glasbergen, K.; Stone, M.; Krishnappan, B.; Dixon, J.; Silins, U.
2015-03-01
While cohesive sediment generally represents a small fraction (<0.5%) of the total sediment mass stored in gravel-bed rivers, it can strongly influence physical and biogeochemical processes in the hyporheic zone and alter aquatic habitat. This research was conducted to examine mechanisms governing the interaction of cohesive sediments with gravel beds in the Elbow River, Alberta, Canada. A series of erosion and deposition experiments with and without a gravel bed were conducted in a 5-m diameter annular flume. The critical shear stress for deposition and erosion of cohesive sediment without gravel was 0.115 Pa and 0.212 Pa, respectively. In experiments with a gravel bed, cohesive sediment moved from the water column into the gravel bed via the coupling of surface and pore water flow. Once in the gravel bed, cohesive sediments were not mobilized under the maximum applied shear stresses (1.11 Pa) used in the experiment. The gravel bed had an entrapment coefficient (ratio between the entrapment flux and the settling flux) of 0.2. Accordingly, when flow conditions are sufficient to produce a shear stress that will mobilize the armour layer of the gravel bed (>16 Pa), cohesive materials trapped within the gravel bed will be entrained and transported into the Glenmore Reservoir, where sediment-associated nutrients may pose treatment challenges to the drinking water supply.
Bigman, Galya; Rajesh, Vandita; Koehly, Laura M; Strong, Larkin L; Oluyomi, Abiodun O; Strom, Sara S; Wilkinson, Anna V
2015-07-01
Existing racial/ethnic disparities in physical activity during childhood increase Hispanics' risk of developing chronic diseases, which serves to increase health disparities. This study examined associations of family cohesion and conflict with self-reported moderate-to-vigorous physical activity (MVPA), controlling for psychosocial covariates such as subjective social status, anxiety, and sensation-seeking. 1000 Mexican origin adolescents reported their MVPA levels approximately 2 years apart. Psychosocial covariates, family cohesion and conflict were measured at the first assessment. Generalized Linear Models were used to prospectively examine the relationship between family cohesion and conflict and subsequent MVPA based on 711 participants who had low levels of baseline MVPA. 35% of boys and 24% of girls reported adequate MVPA levels at follow-up; girls were less likely to report adequate MVPA (RR = 0.76; 95% CI: 0.61-0.93) than boys. Overall, family cohesion was associated with MVPA (P = .01), but family cohesion was not (P = .41). Gender-based analyses revealed that adequate MVPA was associated with family cohesion (RR = 1.40; 95% CI: 1.03-1.88), sensation seeking (RR = 1.05; 95% CI: 1.00-1.10), and age (RR = 0.85; 95% CI: 0.74-0.98) among girls and with subjective social status (RR = 1.20; 95% CI: 1.08-1.33) among boys. The family social environment and gender differences should be addressed in health promotion programs targeting MVPA.
A new Approach for Quantifying Root-Reinforcement of Streambanks: the RipRoot Model
NASA Astrophysics Data System (ADS)
Pollen, N. L.; Simon, A.
2003-12-01
Riparian vegetation plays an important role in controlling geotechnical and fluvial processes acting along and within streambanks through the binding effects of roots. Quantification of this mechanical effect is therefore essential to accurately model streambank stability. Until now, most attempts to include the effects of root reinforcement by riparian vegetation have used root-cohesion values estimated using the Wu et al. (1979) equation, requiring the tensile strengths and diameters of the roots crossing the potential shear-plane. However, the Wu et al. equation is a static model that assumes that all roots break, and that they all break simultaneously. Field observations and laboratory experiments have shown that in reality the roots do not all break simultaneously, and that the breaking of roots during mass failure is in fact a dynamic process. Static models such as the Wu et al. equation are therefore likely to produce overestimations of cohesion due to roots. As a response to this concern, a dynamic root reinforcement model (RipRoot) was developed, based on the concepts of fiber bundle models (FBM's) used in materials science. Within the model the root-soil system is loaded incrementally resulting in progressive root breaking and redistribution of stresses from the broken roots to the remaining intact roots in the soil matrix. The redistribution and loading process continues until either all of the roots have broken, or equilibrium is reached where the root network supports the driving force imposed on the bank. The increase in bank cohesion using the static Wu et al. equation are 18% to 38% higher than RipRoot for riparian tree species, including Black Willow, Sandbar Willow, Cottonwood, River Birch and Eastern Sycamore, and 49% higher for Switch Grass. These variations in cohesion values can have a significant impact on streambank Factor of Safety (Fs) values calculated using the Simon et al. (2000) bank-stability model. For example, a 3m high silt streambank had a Fs of 0.98 without vegetation, indicating instability. With the addition of cohesion from 200 River Birch roots this value increased to 1.22 using the RipRoot value (Conditionally Stable) and 1.37 using the Wu et al. equation (Stable). In this example both of the root models produced cohesion values that were large enough to make the bank more stable, but the more conservative value from RipRoot suggests the bank may only be conditionally stable. Results to date indicate that the dynamic nature of RipRoot removes some of the overestimation from the static equation of Wu et al. (1979), therefore producing more realistic values for root reinforcement, which are particularly useful and important in the context of river management and restoration.
Social Capital or Social Cohesion: What Matters for Subjective Well-Being?
ERIC Educational Resources Information Center
Klein, Carlo
2013-01-01
The theoretical analysis of the concepts of social capital and of social cohesion shows that social capital should be considered as a micro concept whereas social cohesion, being a broader concept than social capital, is a more appropriate concept for macro analysis. Therefore, we suggest that data on the individual level should only be used to…
Comparison of Group Cohesion, Class Participation, and Exam Performance in Live and Online Classes
ERIC Educational Resources Information Center
Galyon, Charles E.; Heaton, Eleanore C. T.; Best, Tiffany L.; Williams, Robert L.
2016-01-01
Though class participation and group cohesion have shown some potential to promote student performance in conventional classrooms, their efficacy has not yet been demonstrated in an online-class setting. Group cohesion, defined as member attraction to and self-identification with a group, is thought to promote positive interdependence and the…
Developing Cohesive Leadership Means Addressing All Parts of the System
ERIC Educational Resources Information Center
Fisher, Troyce
2010-01-01
In her role with the School Administrators of Iowa leading Iowa's leadership grant from The Wallace Foundation, the author works with a coalition of individuals and groups striving to implement a cohesive leadership system for school leaders. Efforts to create a cohesive leadership system in Iowa for the past nine years have resulted in many…
Effects of a Low-Element Challenge Course on Abstinence Self-Efficacy and Group Cohesion
ERIC Educational Resources Information Center
Clem, Jamie M.; Smith, Thomas E.; Richards, Kristin V.
2012-01-01
Substance abuse researchers identify self-efficacy and group cohesion as important components in alcohol and other drug-dependency treatment. Objectives: The purpose of this single-group, pretest-posttest study is to explore the therapeutic value of a challenge course intervention on the self-efficacy and group cohesion of nine chemically…
The Development of Cohesion in a Learner Corpus
ERIC Educational Resources Information Center
Neary-Sundquist, Colleen A.
2013-01-01
This study examines the use of cohesive devices (pragmatic markers and conjunctions) in a 24,000-word corpus of transcribed oral data from 47 learners and native speakers of English. Both of these cohesive devices increase with proficiency level, but not in the same way. Conjunction use seems to increase steadily, and only the differences between…
2016-06-01
7 Development of Cohesive Finite Element Method (CFEM) Capability ................................7 3D...Cohesive Finite Element Method (CFEM) framework A new scientific framework and technical capability is developed for the computational analyses of...this section should shift from reporting activities to reporting accomplishments. Development of Cohesive Finite Element Method (CFEM) Capability
ERIC Educational Resources Information Center
Gray, Tara M.; Rubel, Deborah
2018-01-01
The purpose of this study was to develop a grounded theory of how adolescents experience the cohesion process in rural school counseling groups. A total of 20 individual interviews with 7 participants were conducted. Data analysis generated the central category of the cohesion process as "sticking together," which describes a "tight…
Exploring Group Cohesion in a Higher Education Field Experience
ERIC Educational Resources Information Center
Malcarne, Brian Keith
2012-01-01
The purpose of this study was to gain understanding into the experience of group cohesion for university students participating in an academic field experience. A mixed methods approach was used following a two-phase, sequential research design to help provide a more complete explanation of how group cohesion was impacted by the field experience.…
Anxiety Disorders and Latinos: The Role of Family Cohesion and Family Discord
ERIC Educational Resources Information Center
Priest, Jacob B.; Denton, Wayne
2012-01-01
Family cohesion has shown to be associated with lower psychological distress and other risk behaviors for Latinos, but little is known about the relationship of family cohesion, family discord, and anxiety disorders. Using data from the National Latino and Asian American Study (n = 2,554), this study examines the relationship between family…
Family Cohesion and Romantic and Sexual Initiation: A Three Wave Longitudinal Study
ERIC Educational Resources Information Center
de Graaf, Hanneke; van de Schoot, Rens; Woertman, Liesbeth; Hawk, Skyler T.; Meeus, Wim
2012-01-01
Although the relation between family relationships and the timing of sexual debut has been the focus of many studies, research on mediating factors is scarce. This study examines whether low levels of family cohesion result in an earlier onset of romantic and sexual experiences, and whether the link between family cohesion and an early sexual…
The Measurement of the Perception of Cohesion: A Second Language Example.
ERIC Educational Resources Information Center
Anderson, Jonathan
Within the framework of a general model of communication, a model of language communication has been developed and applied to the perception of cohesion. To measure students' perception of textual cohesion, a pilot study in the United Kingdom built "noise" into texts by deleting parts of each texts. Subjects, 59 nonremedial students whose first…
Referential Cohesion and Logical Coherence of Narration after Closed Head Injury
ERIC Educational Resources Information Center
Davis, G. Albyn; Coelho, Carl A.
2004-01-01
A group with closed head injury was compared to neurologically intact controls regarding the referential cohesion and logical coherence of narrative production. A sample of six stories was obtained with tasks of cartoon-elicited story-telling and auditory-oral retelling. We found deficits in the clinical group with respect to referential cohesion,…
Erdem, Özcan; Van Lenthe, Frank J; Prins, Rick G; Voorham, Toon A J J; Burdorf, Alex
2016-01-01
Various studies have reported socioeconomic inequalities in mental health among urban residents. This study aimed at investigating whether neighborhood social cohesion influences the associations between socio-economic factors and psychological distress. Cross-sectional questionnaire study on a random sample of 18,173 residents aged 16 years and older from 211 neighborhoods in the four largest cities in the Netherlands. Psychological distress was the dependent variable (scale range 10-50). Neighborhood social cohesion was measured by five statements and aggregated to the neighborhood level using ecometrics methodology. Multilevel linear regression analyses were used to investigate cross-level interactions, adjusted for neighborhood deprivation, between individual characteristics and social cohesion with psychological distress. The mean level of psychological distress among urban residents was 17.2. Recipients of disability, social assistance or unemployment benefits reported higher psychological distress (β = 5.6, 95%CI 5.2 to 5.9) than those in paid employment. Persons with some or great financial difficulties reported higher psychological distress (β = 3.4, 95%CI 3.2 to 3.6) than those with little or no financial problems. Socio-demographic factors were also associated with psychological distress, albeit with much lower influence. Living in a neighborhood with high social cohesion instead of low social cohesion was associated with a lower psychological distress of 22% among recipients of disability, social assistance or unemployment benefits and of 13% among citizens with financial difficulties. Residing in socially cohesive neighborhoods may reduce the influence of lack of paid employment and financial difficulties on psychological distress among urban adults. Urban policies aimed at improving neighborhood social cohesion may contribute to decreasing socio-economic inequalities in mental health.
Erdem, Özcan; Van Lenthe, Frank J.; Prins, Rick G.; Voorham, Toon A. J. J.; Burdorf, Alex
2016-01-01
Background Various studies have reported socioeconomic inequalities in mental health among urban residents. This study aimed at investigating whether neighborhood social cohesion influences the associations between socio-economic factors and psychological distress. Methods Cross-sectional questionnaire study on a random sample of 18,173 residents aged 16 years and older from 211 neighborhoods in the four largest cities in the Netherlands. Psychological distress was the dependent variable (scale range 10–50). Neighborhood social cohesion was measured by five statements and aggregated to the neighborhood level using ecometrics methodology. Multilevel linear regression analyses were used to investigate cross-level interactions, adjusted for neighborhood deprivation, between individual characteristics and social cohesion with psychological distress. Results The mean level of psychological distress among urban residents was 17.2. Recipients of disability, social assistance or unemployment benefits reported higher psychological distress (β = 5.6, 95%CI 5.2 to 5.9) than those in paid employment. Persons with some or great financial difficulties reported higher psychological distress (β = 3.4, 95%CI 3.2 to 3.6) than those with little or no financial problems. Socio-demographic factors were also associated with psychological distress, albeit with much lower influence. Living in a neighborhood with high social cohesion instead of low social cohesion was associated with a lower psychological distress of 22% among recipients of disability, social assistance or unemployment benefits and of 13% among citizens with financial difficulties. Conclusions Residing in socially cohesive neighborhoods may reduce the influence of lack of paid employment and financial difficulties on psychological distress among urban adults. Urban policies aimed at improving neighborhood social cohesion may contribute to decreasing socio-economic inequalities in mental health. PMID:27280601
Trinh-Shevrin, Chau; Yen, Irene H.; Kwon, Simona C.
2016-01-01
Introduction Neighborhood factors are increasingly recognized as determinants of health. Neighborhood social cohesion may be associated with physical activity, but previous studies examined data aggregated across racial/ethnic groups. We assessed whether neighborhood social cohesion was associated with physical activity in a nationally representative data set and explored the role of race/ethnicity. Methods We combined National Health Interview Survey data from 2013 and 2014 (n = 64,754) and constructed a neighborhood social cohesion score by summing responses to 4 questions. The outcome of meeting aerobic physical activity guidelines was defined as 150 or more minutes per week of moderate activity or 75 or more minutes of vigorous activity. Multivariable models regressing physical activity on neighborhood social cohesion were adjusted for demographic factors; interaction analyses assessed effect modification by race/ethnicity. Results In adjusted analyses, a 1-unit increase in the neighborhood social cohesion score was associated with higher odds of meeting physical activity guidelines (odds ratio [OR], 1.04; 95% confidence interval [CI], 1.03–1.05). Neighborhood social cohesion and physical activity were associated among non-Hispanic white adults (OR, 1.30; 95% CI, 1.20–1.42) and Hispanic adults (OR, 1.18; 95% CI, 1.03–1.34]) but not among non-Hispanic black or Asian American adults (Chinese, Filipino, and Asian Indians). Conclusion Neighborhood social cohesion was associated with meeting physical activity guidelines in a nationally representative sample; this association may be most meaningful for non-Hispanic white and Hispanic populations. Additional studies are needed to identify neighborhood factors that help non-Hispanic black and Asian Americans to meet physical activity guidelines. PMID:27930284
Yi, Stella S; Trinh-Shevrin, Chau; Yen, Irene H; Kwon, Simona C
2016-12-08
Neighborhood factors are increasingly recognized as determinants of health. Neighborhood social cohesion may be associated with physical activity, but previous studies examined data aggregated across racial/ethnic groups. We assessed whether neighborhood social cohesion was associated with physical activity in a nationally representative data set and explored the role of race/ethnicity. We combined National Health Interview Survey data from 2013 and 2014 (n = 64,754) and constructed a neighborhood social cohesion score by summing responses to 4 questions. The outcome of meeting aerobic physical activity guidelines was defined as 150 or more minutes per week of moderate activity or 75 or more minutes of vigorous activity. Multivariable models regressing physical activity on neighborhood social cohesion were adjusted for demographic factors; interaction analyses assessed effect modification by race/ethnicity. In adjusted analyses, a 1-unit increase in the neighborhood social cohesion score was associated with higher odds of meeting physical activity guidelines (odds ratio [OR], 1.04; 95% confidence interval [CI], 1.03-1.05). Neighborhood social cohesion and physical activity were associated among non-Hispanic white adults (OR, 1.30; 95% CI, 1.20-1.42) and Hispanic adults (OR, 1.18; 95% CI, 1.03-1.34]) but not among non-Hispanic black or Asian American adults (Chinese, Filipino, and Asian Indians). Neighborhood social cohesion was associated with meeting physical activity guidelines in a nationally representative sample; this association may be most meaningful for non-Hispanic white and Hispanic populations. Additional studies are needed to identify neighborhood factors that help non-Hispanic black and Asian Americans to meet physical activity guidelines.
Durability and life prediction modeling in polyimide composites
NASA Technical Reports Server (NTRS)
Binienda, Wieslaw K.
1995-01-01
Sudden appearance of cracks on a macroscopically smooth surface of brittle materials due to cooling or drying shrinkage is a phenomenon related to many engineering problems. Although conventional strength theories can be used to predict the necessary condition for crack appearance, they are unable to predict crack spacing and depth. On the other hand, fracture mechanics theory can only study the behavior of existing cracks. The theory of crack initiation can be summarized into three conditions, which is a combination of a strength criterion and laws of energy conservation, the average crack spacing and depth can thus be determined. The problem of crack initiation from the surface of an elastic half plane is solved and compares quite well with available experimental evidence. The theory of crack initiation is also applied to concrete pavements. The influence of cracking is modeled by the additional compliance according to Okamura's method. The theoretical prediction by this structural mechanics type of model correlates very well with the field observation. The model may serve as a theoretical foundation for future pavement joint design. The initiation of interactive cracks of quasi-brittle material is studied based on a theory of cohesive crack model. These cracks may grow simultaneously, or some of them may close during certain stages. The concept of crack unloading of cohesive crack model is proposed. The critical behavior (crack bifurcation, maximum loads) of the cohesive crack model are characterized by rate equations. The post-critical behavior of crack initiation is also studied.
Jo, Kae Hwa; Song, Byung Sook
2012-10-01
The purposes of this study were to explore the effects of family cohesion and subjective happiness on death anxiety of Korean elders and to identify other factors contributing to death anxiety. The participants were 280 elders who lived in P metropolitan city. Data were collected between November 5, 2011 and January 12, 2012 using the Short Portable Mental Status Questionnaire (SPMSQ), Family Cohesion Evaluation Scale, Subjective Happiness Scale, and Fear of Death Scale (FODS). Data were analyzed using the SPSS/WIN 19.0 program. Family cohesion, marital status, religious activity, perceived health status, and subjective happiness were included in the factors affecting death anxiety of Korean elders. These variables explained 50.1% of death anxiety. The results of the study indicate that these variables should be considered in developing nursing intervention programs to decrease death anxiety and increase family cohesion and subjective happiness for life integration in Korean elders.
Benson, Alex J; Eys, Mark A; Irving, P Gregory
2016-04-01
Many athletes experience a discrepancy between the roles they expect to fulfill and the roles they eventually occupy. Drawing from met expectations theory, we applied response surface methodology to examine how role expectations, in relation to role experiences, influence perceptions of group cohesion among Canadian Interuniversity Sport athletes (N = 153). On the basis of data from two time points, as athletes approached and exceeded their role contribution expectations, they reported higher perceptions of task cohesion. Furthermore, as athletes approached and exceeded their social involvement expectations, they reported higher perceptions of social cohesion. These response surface patterns-pertaining to task and social cohesion-were driven by the positive influence of role experiences. On the basis of the interplay between athletes' role experiences and their perception of the group environment, efforts to improve team dynamics may benefit from focusing on improving the quality of role experiences, in conjunction with developing realistic role expectations.
Santos, Susana; Crespo, Carla; Canavarro, M Cristina; Kazak, Anne E
2017-01-01
Family functioning is associated with adaptation in pediatric illness. This study examines the role of parents’ relationships (specifically romantic attachment) as a predictor of family ritual meaning and family cohesion for parents and their children with cancer. The dyads, 58 partnered Portuguese parents and their children in treatment, reported on family ritual meaning and family cohesion at Time 1 (T1) and after 6 months (T2). Parents also completed the questionnaire assessing romantic attachment at T1. Parents’ avoidant attachment, but not anxious attachment, predicted lower family ritual meaning and family cohesion after 6 months. T2 family ritual meaning mediated the relationship between T1 avoidant attachment and T2 family cohesion. Parents’ avoidant attachment may have a negative effect on family functioning in parents and children. Clinical intervention to address avoidant attachment or/and to promote family ritual meaning may help strengthen family ties.
Social cohesion and self-rated health among adults in South Africa: The moderating role of race.
Olamijuwon, Emmanuel O; Odimegwu, Clifford O; De Wet, Nicole
2018-05-01
In African countries including South Africa, the nexus between social cohesion and health remains under-researched. Using data from the 2012 South African social attitudes survey with a sample of 1988 adults in South Africa aged 18 years or older, we used the collective efficacy theory by Sampson and colleagues to examine the relationship between social cohesion and self-rated health in an African sample. We also examined how this relationship differed by race. Results from the multivariate analysis after adjusting for covariates suggested that adults in the highest tertile of social cohesion were more likely to report moderate or good health compared to those in the lowest tertile. Sub-group analysis provided no evidence that the relationship was moderated by race. These findings corroborate prior evidence that social cohesion is important for improving the health of adults. Copyright © 2018 Elsevier Ltd. All rights reserved.
Lagisetty, Pooja A; Wen, Ming; Choi, Hwajung; Heisler, Michele; Kanaya, Alka M; Kandula, Namratha R
2016-12-01
South Asians have a high burden of cardiovascular disease compared to other racial/ethnic groups in the United States. Little has been done to evaluate how neighborhood environments may influence cardiovascular risk factors including hypertension and type 2 diabetes in this immigrant population. We evaluated the association of perceived neighborhood social cohesion with hypertension and type 2 diabetes among 906 South Asian adults who participated in the Mediators of Atherosclerosis in South Asians Living in America Study. Multivariable logistic regression adjusted for demographic, socioeconomic, psychosocial, and physiologic covariates. Subgroup analyses examined whether associations differed by gender. South Asian women living in neighborhoods with high social cohesion had 46 % reduced odds of having hypertension than those living in neighborhoods with low social cohesion (OR 0.54, 95 % CI 0.30-0.99). Future research should determine if leveraging neighborhood social cohesion prevents hypertension in South Asian women.
Neighborhood Social Cohesion and Prevalence of Hypertension and Diabetes in a South Asian Population
Lagisetty, Pooja A.; Wen, Ming; Choi, Hwajung; Heisler, Michele; Kanaya, Alka M.; Kandula, Namratha R.
2016-01-01
South Asians have a high burden of cardiovascular disease compared to other racial/ethnic groups in the United States. Little has been done to evaluate how neighborhood environments may influence cardiovascular risk factors including hypertension and type 2 diabetes in this immigrant population. We evaluated the association of perceived neighborhood social cohesion with hypertension and type 2 diabetes among 906 South Asian adults who participated in the Mediators of Atherosclerosis in South Asians Living in America (MASALA) Study. Multivariable logistic regression adjusted for demographic, socioeconomic, psychosocial, and physiologic covariates. Subgroup analyses examined whether associations differed by gender. South Asian women living in neighborhoods with high social cohesion had 46% reduced odds of having hypertension than those living in neighborhoods with low social cohesion (OR=0.54, 95% CI 0.30–0.99). Future research should determine if leveraging neighborhood social cohesion prevents hypertension in South Asian women. PMID:26527589
Tracking cohesive subgroups over time in inferred social networks
NASA Astrophysics Data System (ADS)
Chin, Alvin; Chignell, Mark; Wang, Hao
2010-04-01
As a first step in the development of community trackers for large-scale online interaction, this paper shows how cohesive subgroup analysis using the Social Cohesion Analysis of Networks (SCAN; Chin and Chignell 2008) and Data-Intensive Socially Similar Evolving Community Tracker (DISSECT; Chin and Chignell 2010) methods can be applied to the problem of identifying cohesive subgroups and tracking them over time. Three case studies are reported, and the findings are used to evaluate how well the SCAN and DISSECT methods work for different types of data. In the largest of the case studies, variations in temporal cohesiveness are identified across a set of subgroups extracted from the inferred social network. Further modifications to the DISSECT methodology are suggested based on the results obtained. The paper concludes with recommendations concerning further research that would be beneficial in addressing the community tracking problem for online data.
Improving Cohesion in L2 Writing: A Three-Strand Approach to Building Lexical Cohesion
ERIC Educational Resources Information Center
Johnson, Mark
2017-01-01
This article presents a three-strand approach to help L2 writers in English as a foreign language (EFL) and English as a second language (ESL) instructional contexts achieve greater cohesion in their written work. The approach focuses on (1) the analysis of authentic texts, (2) the development of productive vocabulary, and (3) information…
Say More and Be More Coherent: How Text Elaboration and Cohesion Can Increase Writing Quality
ERIC Educational Resources Information Center
Crossley, Scott A.; McNamara, Danielle S.
2016-01-01
This study examines links between essay quality and text elaboration and text cohesion. For this study, 35 students wrote two essays (on two different prompts) and for each, were given 15 minutes to elaborate on their original text. An expert in discourse comprehension then modified the original and elaborated essays to increase cohesion,…
ERIC Educational Resources Information Center
Parton, Brent T.
2011-01-01
Strategies aiming to foster social cohesion seek to enhance predictability and trust among heterogeneous actors. Although undoubtedly nation-states remain the dominant context for examining social cohesion, in Europe and in South America, nation-states have formed regional organizations to support political stability and economic cooperation in a…
Social Cohesion and the Labour Market: Societal Regimes of Civic Attitudes and Labour Market Regimes
ERIC Educational Resources Information Center
Dimeglio, Isabelle; Janmaat, Jan Germen; Mehaut, Philippe
2013-01-01
The aim of this paper is to test the connections between the indicators used in the literature on social cohesion, which usually reflect "general" values or behaviours, and indicators specific to a particular space, namely the labour market. A key question is the stability of the social cohesion's indicators when moving from a societal…
ERIC Educational Resources Information Center
Enyi, Amaechi Uneke; Chitulu, Mark Ononiwu
2015-01-01
This study, entitled, "Texture and textuality in Political Discourse: A Study of Cohesive Devices in President Goodluck Jonathan's Inaugural Address-May, 2011" was an analysis of the lexical cohesive devices employed by Nigeria's President Goodluck Jonathan in crafting his May, 2011's Presidential Inaugural Address (PIA). Guided by the…
ERIC Educational Resources Information Center
Martín Babarro, Javier; Díaz-Aguado, María José; Martínez Arias, Rosario; Steglich, Christian
2017-01-01
This study addresses the interacting effects of classroom cohesion and hierarchy on the relationships between victimization and aggression with peer acceptance and rejection. Classroom cohesion and hierarchy were constructed from friendship nominations. Multilevel analysis conducted in a sample of seventh- and eighth-grade students from the…
ERIC Educational Resources Information Center
Chan, Joseph; To, Ho-Pong; Chan, Elaine
2006-01-01
Despite its growing currency in academic and policy circles, social cohesion is a term in need of a clearer and more rigorous definition. This article provides a critical review of the ways social cohesion has been conceptualized in the literature in many cases, definitions are too loosely made, with a common confusion between the content and the…
ERIC Educational Resources Information Center
Rajulton, Fernando; Ravanera, Zenaida R.; Beaujot, Roderic
2007-01-01
Social cohesion is a concept difficult to define and to measure. As there can be many definitions, so there can be many measurements. The main problem, either in defining or measuring the concept, is its multilevel and multidimensional nature. At one extreme, "country" is the most commonly used level to view social cohesion but…
Construct Validation and Application of a Common Measure of Social Cohesion in 33 European Countries
ERIC Educational Resources Information Center
Dickes, Paul; Valentova, Marie; Borsenberger, Monique
2010-01-01
The aim of the paper is to assess the construct validation of a multidimensional measure of social cohesion which is well theoretically grounded and has an equivalent/comparable interpretation across all European countries. Up-to-now published research on social cohesion is deficient in either one or both of these important aspects. This paper…
Campos, Paola A; Falb, Kathryn L; Hernández, Sara; Díaz-Olavarrieta, Claudia; Gupta, Jhumka
2017-01-01
To document the frequency and forms of street harassment and examine the association between street harassment experiences and perceptions of social cohesion. Baseline survey data collected among women seeking care in public health clinics in Mexico City were used for analysis. Nearly two-thirds (62.8%) of women reported experiencing some form of street harassment in the prior month; women with street harassment experiences reported significantly lower perceived social cohesion (b=-0.46; 95%CI: -0.69,-0.22). Findings indicate reducing street harassment may have important implications for improving women's perceived social cohesion and their safety in Mexico City.
Neighborhood cohesion, neighborhood disorder, and cardiometabolic risk.
Robinette, Jennifer W; Charles, Susan T; Gruenewald, Tara L
2018-02-01
Perceptions of neighborhood disorder (trash, vandalism) and cohesion (neighbors trust one another) are related to residents' health. Affective and behavioral factors have been identified, but often in studies using geographically select samples. We use a nationally representative sample (n = 9032) of United States older adults from the Health and Retirement Study to examine cardiometabolic risk in relation to perceptions of neighborhood cohesion and disorder. Lower cohesion is significantly related to greater cardiometabolic risk in 2006/2008 and predicts greater risk four years later (2010/2012). The longitudinal relation is partially accounted for by anxiety and physical activity. Copyright © 2017 Elsevier Ltd. All rights reserved.
Productive aging via volunteering: Does social cohesion influence level of engagement?
Johnson, Kimberly J; Latham-Mintus, Kenzie; Poey, Judith L
2018-04-26
This study investigated whether neighborhood social cohesion influenced volunteer intensity over two years. The sample was drawn from Health and Retirement Study respondents who completed the 2010 or 2012 Psychosocial and Lifestyle Questionnaire (n = 12,929). Results showed that compared to nonvolunteers, a one-unit increase in neighborhood social cohesion increased the odds of moderate (OR: 1.07, p < .05) and high volunteering (OR: 1.10, p < .001). However, other productive roles, social contact, and education were significant in distinguishing high intensity from moderate volunteering while neighborhood social cohesion was not. Social workers should consider the neighborhood environment when recruiting volunteers.
Chen, Chun-Hsi Vivian; Tang, Ya-Yun; Wang, Shih-Jon
2009-12-01
The authors investigated the mechanism of group cohesion in the relationship between (a) task interdependence and goal interdependence and (b) individuals' organizational citizenship behavior (OCB). The authors adopted a multilevel perspective to facilitate understanding of the complex relations among variables. They collected data from 53 supervisors and 270 employees from R&D departments in Taiwan. The authors found that group cohesion fully mediated the effects of task interdependence and goal interdependence on employees' OCB. In addition, task interdependence had a greater effect on group cohesion than did goal interdependence. The authors discuss implications and suggestions for future research.
Feiss, Michael; Young Min, Jea; Sultana, Sawsan; Patel, Priyal; Sippy, Jean
2015-01-01
During DNA replication by the λ-like bacteriophages, immature concatemeric DNA is produced by rolling circle replication. The concatemers are processed into mature chromosomes with cohesive ends, and packaged into prohead shells, during virion assembly. Cohesive ends are generated by the viral enzyme terminase, which introduces staggered nicks at cos, an approx. 200 bp-long sequence containing subsites cosQ, cosN and cosB. Interactions of cos subsites of immature concatemeric DNA with terminase orchestrate DNA processing and packaging. To initiate DNA packaging, terminase interacts with cosB and nicks cosN. The cohesive ends of N15 DNA differ from those of λ at 2/12 positions. Genetic experiments show that phages with chromosomes containing mismatched cohesive ends are functional. In at least some infections, the cohesive end mismatch persists through cyclization and replication, so that progeny phages of both allelic types are produced in the infected cell. N15 possesses an asymmetric packaging specificity: N15 DNA is not packaged by phages λ or 21, but surprisingly, N15-specific terminase packages λ DNA. Implications for genetic interactions among λ-like bacteriophages are discussed. PMID:26633301
Sharabi, Adi; Levi, Uzi; Margalit, Malka
2012-01-01
The study examined the contributions of individual and familial variables for the prediction of loneliness as a developmental risk and the sense of coherence as a protective factor. The sample consisted of 287 children from grades 5-6. Their loneliness, sense of coherence, hope, effort, and family climate were assessed. Separate hierarchical multiple regression analyses revealed that family cohesion and children's hope contributed to the explanation of the risk and protective outcomes. Yet, the contribution of the family adaptability was not significant. Cluster analysis of the family climate dimensions (i.e., cohesion and adaptability) was performed to clarify the interactive roles of family adaptability together with family cohesion. The authors identified 4 separate family profiles: Children in the 2 cohesive families' clusters (Cohesive Structured Families and Cohesive Adaptable Families) reported the lowest levels of loneliness and the highest levels of personal strengths. Children within rigid and noncohesive family cluster reported the highest levels of loneliness and the lowest levels of children's sense of coherence. The unique role of the family flexibility within nonsupportive family systems was demonstrated. The results further clarified the unique profiles' characteristics of the different family clusters and their adjustment indexes in terms of loneliness and personal strengths.
Santos, Susana; Crespo, Carla; Canavarro, M Cristina; Kazak, Anne E
2015-08-01
Family rituals are associated with adaptive functioning in pediatric illness, including quality of life (QoL). This article explores the role of family cohesion and hope as mediators of this association in children with cancer and their parents. Portuguese children with cancer (N = 389), on- and off-treatment, and one of their parents completed self-report measures. Structural equation modeling was used to examine direct and indirect links between family rituals and QoL. When children and parents reported higher levels of family rituals, they also reported more family cohesion and hope, which were linked to better QoL. At the dyadic level, children's QoL was related to parents' family rituals through the child's family cohesion. This model was valid across child's age-group, treatment status, and socioeconomic status. Family rituals are important in promoting QoL in pediatric cancer via family cohesion and hope individually and via family cohesion in terms of parent-child interactions. © The Author 2015. Published by Oxford University Press on behalf of the Society of Pediatric Psychology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.
The protective effect of neighborhood social cohesion in child abuse and neglect.
Maguire-Jack, Kathryn; Showalter, Kathryn
2016-02-01
Relations between parents within a neighborhood have the potential to provide a supportive environment for healthy and positive parenting. Neighborhood social cohesion, or the mutual trust and support among neighbors, is one process through which parenting may be improved. The current study investigates the association between neighborhood social cohesion and abuse and neglect, as well as specific types of abuse and neglect. The sample for the study is comprised of 896 parents in one urban Midwestern County in the United States. Participants were recruited from Women, Infants, and Children clinics. Negative binomial regression is used to examine the association between neighborhood social cohesion and child maltreatment behaviors, as measured by the Conflict Tactics Scale, Parent-to-Child Version (Straus et al., 1998). In this sample of families, neighborhood social cohesion is associated with child neglect, but not abuse. In examining the relationship with specific types of abuse and neglect, it was found that neighborhood social cohesion may have a protective role in some acts of neglect, such as meeting a child's basic needs, but not potentially more complex needs like parental substance abuse. Copyright © 2015 Elsevier Ltd. All rights reserved.
van Oosterom, L; Montgomery, J C; Jeffs, A G; Radford, C A
2016-01-11
Soundscapes provide a new tool for the study of fish communities. Bigeyes (Pempheris adspersa) are nocturnal planktivorous reef fish, feed in loose shoals and are soniferous. These vocalisations have been suggested to be contact calls to maintain group cohesion, however direct evidence for this is absent, despite the fact that contact calls are well documented for many other vertebrates, including marine mammals. For fish, direct evidence for group cohesion signals is restricted to the use of visual and hydrodynamic cues. In support of adding vocalisation as a contributing cue, our laboratory experiments show that bigeyes significantly increased group cohesion when exposed to recordings of ambient reef sound at higher sound levels while also decreasing vocalisations. These patterns of behaviour are consistent with acoustic masking. When exposed to playback of conspecific vocalisations, the group cohesion and vocalisation rates of bigeyes both significantly increased. These results provide the first direct experimental support for the hypotheses that vocalisations are used as contact calls to maintain group cohesion in fishes, making fish the evolutionarily oldest vertebrate group in which this phenomenon has been observed, and adding a new dimension to the interpretation of nocturnal reef soundscapes.
NASA Astrophysics Data System (ADS)
van Oosterom, L.; Montgomery, J. C.; Jeffs, A. G.; Radford, C. A.
2016-01-01
Soundscapes provide a new tool for the study of fish communities. Bigeyes (Pempheris adspersa) are nocturnal planktivorous reef fish, feed in loose shoals and are soniferous. These vocalisations have been suggested to be contact calls to maintain group cohesion, however direct evidence for this is absent, despite the fact that contact calls are well documented for many other vertebrates, including marine mammals. For fish, direct evidence for group cohesion signals is restricted to the use of visual and hydrodynamic cues. In support of adding vocalisation as a contributing cue, our laboratory experiments show that bigeyes significantly increased group cohesion when exposed to recordings of ambient reef sound at higher sound levels while also decreasing vocalisations. These patterns of behaviour are consistent with acoustic masking. When exposed to playback of conspecific vocalisations, the group cohesion and vocalisation rates of bigeyes both significantly increased. These results provide the first direct experimental support for the hypotheses that vocalisations are used as contact calls to maintain group cohesion in fishes, making fish the evolutionarily oldest vertebrate group in which this phenomenon has been observed, and adding a new dimension to the interpretation of nocturnal reef soundscapes.
van Oosterom, L.; Montgomery, J. C.; Jeffs, A. G.; Radford, C. A.
2016-01-01
Soundscapes provide a new tool for the study of fish communities. Bigeyes (Pempheris adspersa) are nocturnal planktivorous reef fish, feed in loose shoals and are soniferous. These vocalisations have been suggested to be contact calls to maintain group cohesion, however direct evidence for this is absent, despite the fact that contact calls are well documented for many other vertebrates, including marine mammals. For fish, direct evidence for group cohesion signals is restricted to the use of visual and hydrodynamic cues. In support of adding vocalisation as a contributing cue, our laboratory experiments show that bigeyes significantly increased group cohesion when exposed to recordings of ambient reef sound at higher sound levels while also decreasing vocalisations. These patterns of behaviour are consistent with acoustic masking. When exposed to playback of conspecific vocalisations, the group cohesion and vocalisation rates of bigeyes both significantly increased. These results provide the first direct experimental support for the hypotheses that vocalisations are used as contact calls to maintain group cohesion in fishes, making fish the evolutionarily oldest vertebrate group in which this phenomenon has been observed, and adding a new dimension to the interpretation of nocturnal reef soundscapes. PMID:26750559
Structural neighbourhood conditions, social cohesion and psychological distress in the Netherlands.
Erdem, Özcan; Prins, Richard G; Voorham, Toon A J J; van Lenthe, Frank J; Burdorf, Alex
2015-12-01
Neighbourhood inequalities in psychological distress are well reported, but underlying mechanisms remain poorly understood. The main purposes of this study were to investigate associations between structural neighbourhood conditions and psychological distress, and to explore the potential mediating role of neighbourhood social cohesion. Cross-sectional questionnaire study on a random sample of 18,173 residents aged ≥ 16 years (response 49%) from the four largest cities in the Netherlands. Psychological distress was measured with the Kessler Psychological Distress Scale (K10). Structural environmental factors under study were neighbourhood socio-economic status (SES), neighbourhood green, urbanity and home maintenance. Neighbourhood social cohesion was measured by five statements and aggregated to the neighbourhood level by using ecometrics methodology. Multilevel linear regression analysis was used to investigate associations of neighbourhoods characteristics with psychological distress, adjusted for individual level characteristics. High neighbourhood SES and neighbourhood social cohesion were associated with decreased psychological distress. Adjusted for individual level characteristics and neighbourhood SES, only neighbourhood social cohesion remained significantly associated with psychological distress. Neighbourhood social cohesion accounted for 38% of the differences in the association between neighbourhood SES and psychological distress. High neighbourhood social cohesion is significantly associated with decreased psychological distress among residents of the four largest cities in the Netherlands. Reducing neighbourhood inequalities in psychological distress may require increasing social interactions among neighbourhood residents. © The Author 2015. Published by Oxford University Press on behalf of the European Public Health Association. All rights reserved.
Laméris, Joran; Hipp, John R; Tolsma, Jochem
2018-05-01
This study examines the effects of neighborhood racial in-group size, economic deprivation and the prevalence of crime on neighborhood cohesion among U.S. whites. We explore to what extent residents' perceptions of their neighborhood mediate these macro-micro relationships. We use a recent individual-level data set, the American Social Fabric Study (2012/2013), enriched with contextual-level data from the U.S. Census Bureau (2010) and employ multi-level structural equation models. We show that the racial in-group size is positively related to neighborhood cohesion and that neighborhood cohesion is lower in communities with a high crime rate. Individuals' perceptions of the racial in-group size partly mediate the relationship between the objective racial in-group size and neighborhood cohesion. Residents' perceptions of unsafety from crime also appear to be a mediating factor, not only for the objective crime rate but also for the objective racial in-group size. This is in line with our idea that racial stereotypes link racial minorities to crime whereby neighborhoods with a large non-white population are perceived to be more unsafe. Residents of the same neighborhood differ in how they perceive the degree of economic decay of the neighborhood and this causes them to evaluate neighborhood cohesion differently, however perceptions of neighborhood economic decay do not explain the link between the objective neighborhood context and neighborhood cohesion. Copyright © 2018. Published by Elsevier Inc.
Pfeil-McCullough, Erin; Bain, Daniel J; Bergman, Jeffery; Crumrine, Danielle
2015-12-01
Emerald ash borer is expected to kill thousands of ash trees in the eastern U.S. This research develops tools to predict the effect of ash tree loss from the urban canopy on landslide susceptibility in Pittsburgh, PA. A spatial model was built using the SINMAP (Stability INdex MAPping) model coupled with spatially explicit scenarios of tree loss (0%, 25%, 50%, and 75% loss of ash trees from the canopy). Ash spatial distributions were estimated via Monte Carlo methods and available vegetation plot data. Ash trees are most prevalent on steeper slopes, likely due to urban development patterns. Therefore, ash loss disproportionately increases hillslope instability. A 75% loss of ash resulted in roughly 800 new potential landslide initiation locations. Sensitivity testing reveals that variations in rainfall rates, and friction angles produce minor changes to model results relative to the magnitude of parameter variation, but reveal high model sensitivity to soil density and root cohesion values. The model predictions demonstrate the importance of large canopy species to urban hillslope stability, particularly on steep slopes and in areas where soils tend to retain water. To improve instability predictions, better characterization of urban soils, particularly spatial patterns of compaction and species specific root cohesion is necessary. The modeling framework developed in this research will enhance assessment of changes in landslide risk due to tree mortality, improving our ability to design economically and ecologically sustainable urban systems. Copyright © 2015 Elsevier B.V. All rights reserved.
Tang, S.Y.; Vashishth, D.
2010-01-01
The risk of fracture increases with age due to the decline of bone mass and bone quality. One of the age-related changes in bone quality occurs through the formation and accumulation of advanced glycation end-products (AGEs) due to non-enzymatic glycation (NEG). However as a number of other changes including increased porosity occur with age and affect bone fragility, the relative contribution of AGEs on the fracture resistance of aging bone is unknown. Using a high-resolution nonlinear finite element model that incorporate cohesive elements and micro-computed tomography-based 3d meshes, we investigated the contribution of AGEs and cortical porosity on the fracture toughness of human bone. The results show that NEG caused a 52% reduction in propagation fracture toughness (R-curve slope). The combined effects of porosity and AGEs resulted in an 88% reduction in propagation toughness. These findings are consistent with previous experimental results. The model captured the age-related changes in the R-curve toughening by incorporating bone quantity and bone quality changes, and these simulations demonstrate the ability of the cohesive models to account for the irreversible dynamic crack growth processes affected by the changes in post-yield material behavior. By decoupling the matrix-level effects due to NEG and intracortical porosity, we are able to directly determine the effects of NEG on fracture toughness. The outcome of this study suggests that it may be important to include the age-related changes in the material level properties by using finite element analysis towards the prediction of fracture risk. PMID:21056419
A Comparative Analysis of Unit Cohesion in Vietnam
2014-06-13
the political process, and result in a communist government; this became known as the Domino Theory . The United States replaced the French and...a theory of linkage; leveraging the political ties of Communist countries, namely the USSR and China, to influence North Vietnam, and deterrence; a...and Henderson provide some of the more popular theories about cohesion. Winkler points out that the relationship between stability, cohesion and
ERIC Educational Resources Information Center
Engebretsen, Martin
2012-01-01
What patterns of multimodal rhetoric characterizes the most successful texts meant for learning--inside or outside school? This article argues that the balance between cohesion and tension in the interplay between modes is an issue at the core of this challenging question. Texts meant for learning need both cohesion and tension in order to be both…
ERIC Educational Resources Information Center
Lightsey, Owen Richard, Jr.; Sweeney, James
2008-01-01
The authors tested whether self-efficacy, coping styles, family cohesion, and meaning in life predicted family satisfaction among 64 mothers of children with disabilities. They also examined whether meaning in life mediated the relationship between cohesion and family satisfaction or served as a resource whose effects on family satisfaction were…
The Republic of Singapore: Informed Questions
2003-01-01
Singaporean society has, until recently, exhibited a high degree of tolerance and social cohesion .7 Yet Singapore exists as a conspicuously wealthy...immigrants threatens to alter Singapore’s ethnic composition and thus undermine the social cohesion upon which the country’s stability and...bold measures in response to perceived threats to the nation’s prized social cohesion . In March 2001, the government initiated high-level dialog
Cooper, Crispin H V; Fone, David L; Chiaradia, Alain J F
2014-04-11
There is now a substantial body of research suggesting that social cohesion, a collective characteristic measured by the levels of trust, reciprocity and formation of strong social bonds within communities, is an important factor in determining health. Of particular interest is the extent to which factors in the built environment facilitate, or impede, the development of social bonds. Severance is a characteristic of physical environments which is hypothesized to inhibit cohesion. In the current study we test a number of characteristics of spatial networks which could be hypothesized to relate either to severance, or directly to community cohesion. Particular focus is given to our most promising variable for further analysis (Convex Hull Maximum Radius 600 m). In the current study we analysed social cohesion as measured at Enumeration District level, aggregated from a survey of 10,892 individuals aged 18 to 74 years in the Caerphilly Health and Social Needs Cohort Study, 2001. In a data mining process we test 16 network variables on multiple scales. The variable showing the most promise is validated in a test on an independent data set. We then conduct a multivariate regression also including Townsend deprivation scores and urban/rural status as predictor variables for social cohesion. We find convex hull maximum radius at a 600 m scale to have a small but highly significant correlation with social cohesion on both data sets. Deprivation has a stronger effect. Splitting the analysis by tertile of deprivation, we find that the effect of severance as measured by this variable is strongest in the most deprived areas. A range of spatial scales are tested, with the strongest effects being observed at scales that match typical walking distances. We conclude that physical connectivity as measured in this paper has a significant effect on social cohesion, and that our measure is unlikely to proxy either deprivation or the urban/rural status of communities. Possible mechanisms for the effect include intrinsic navigability of areas, and the existence of a focal route on which people can meet on foot. Further investigation may lead to much stronger predictive models of social cohesion.
Measuring the impact of spatial network layout on community social cohesion: a cross-sectional study
2014-01-01
Background There is now a substantial body of research suggesting that social cohesion, a collective characteristic measured by the levels of trust, reciprocity and formation of strong social bonds within communities, is an important factor in determining health. Of particular interest is the extent to which factors in the built environment facilitate, or impede, the development of social bonds. Severance is a characteristic of physical environments which is hypothesized to inhibit cohesion. In the current study we test a number of characteristics of spatial networks which could be hypothesized to relate either to severance, or directly to community cohesion. Particular focus is given to our most promising variable for further analysis (Convex Hull Maximum Radius 600 m). Methods In the current study we analysed social cohesion as measured at Enumeration District level, aggregated from a survey of 10,892 individuals aged 18 to 74 years in the Caerphilly Health and Social Needs Cohort Study, 2001. In a data mining process we test 16 network variables on multiple scales. The variable showing the most promise is validated in a test on an independent data set. We then conduct a multivariate regression also including Townsend deprivation scores and urban/rural status as predictor variables for social cohesion. Results We find convex hull maximum radius at a 600 m scale to have a small but highly significant correlation with social cohesion on both data sets. Deprivation has a stronger effect. Splitting the analysis by tertile of deprivation, we find that the effect of severance as measured by this variable is strongest in the most deprived areas. A range of spatial scales are tested, with the strongest effects being observed at scales that match typical walking distances. Conclusion We conclude that physical connectivity as measured in this paper has a significant effect on social cohesion, and that our measure is unlikely to proxy either deprivation or the urban/rural status of communities. Possible mechanisms for the effect include intrinsic navigability of areas, and the existence of a focal route on which people can meet on foot. Further investigation may lead to much stronger predictive models of social cohesion. PMID:24725759
LIU, Liang; LIU, Cuilian; ZHAO, Xudong
2017-01-01
Background Between 22% and 58% of patients in primary care settings complain of somatic symptoms. Previous research has found that somatization was associated with anger traits and family functions. However, studies that specifically assess the moderating effect of family function in how anger traits become somatic complaints are lacking. Aim This study was designed to examine whether the variances in family cohesion and family adaptability moderated the strength of the relationship between anger traits and somatization. Methods A cross-section design was conducted and 2008 college students were recruited from a comprehensive university in Shanghai. All participants finished questionnaires including Symptom Check List- 90 (SCL-90), State-Trait Anger Expression Inventory 2 (STAXI-2, Chinese version) and Family Adaptability and Cohesion Scale, second edition (FACES II, Chinese Version) to assess their degree of current somatization, anger trait and family function. Hierarchical linear regression analysis (Enter) was conducted respectively for men and women to examine the moderation effect of family cohesion and family adaptability in the association between anger and somatization. Results Somatic symptoms were significantly linked in the expected directions with depression and anger trait for both genders. Family cohesion and family adaptability were negatively associated with somatic symptoms. For female college students family cohesion was found to moderate the link between anger trait and somatization, but for male college students the moderation effect of family cohesion was marginally significant. The moderating role of family adaptability was significant for neither male nor female after current depressive symptoms were accounted for. Conclusion Proneness to anger is an independent predictor of somatization. For women, a high level of family cohesion was a protective factor which could reduce the influence of anger trait on somatic symptoms. Without comorbidity of current depression, family adaptability to some degree exempted individuals with anger proneness from developing somatic complaints. Interventions that integrate family cohesion cultivation, family flexibility fostering and depression treatment might be more effective for somatic patients high in anger trait. PMID:28769543
Shimizu, Karina; Tariq, Mohammad; Costa Gomes, Margarida F; Rebelo, Luís P N; Canongia Lopes, José N
2010-05-06
Molecular dynamics simulations were used to calculate the density and the cohesive molar internal energy of seventeen different ionic liquids in the liquid phase. The results were correlated with previously reported experimental density and molar refraction data. The link between the dispersive component of the total cohesive energy of the fluid and the corresponding molar refraction was established in an unequivocal way. The results have shown that the two components of the total cohesive energy (dispersive and electrostatic) exhibit strikingly different trends and ratios along different families of ionic liquids, a notion that may help explain their diverse behavior toward different molecular solutes and solvents.
All Together Now: Measuring Staff Cohesion in Special Education Classrooms
Kratz, Hilary E.; Locke, Jill; Piotrowski, Zinnia; Ouellette, Rachel R.; Xie, Ming; Stahmer, Aubyn C.; Mandell, David S.
2015-01-01
This study sought to validate a new measure, the Classroom Cohesion Survey (CCS), designed to examine the relationship between teachers and classroom assistants in autism support classrooms. Teachers, classroom assistants, and external observers showed good inter-rater agreement on the CCS and good internal consistency for all scales. Simple factor structures were found for both teacher- and classroom assistant–rated scales, with one-factor solutions for both scales. Paired t tests revealed that on average, classroom assistants rated classroom cohesion stronger than teachers. The CCS may be an effective tool for measuring cohesion between classroom staff and may have an important impact on various clinical and implementation outcomes in school settings. PMID:26213443
NASA Technical Reports Server (NTRS)
Horgan, Briony H. N.; Bell, James F., III
2012-01-01
Meter-scale MRO/HiRISE camera images of dune slipfaces in the north polar sand sea of Mars reveal the presence of deep alcoves above depositional fans. These features are apparently active under current climatic conditions, because they form between observations taken in subsequent Mars years. Recently, other workers have hypothesized that the alcoves form due to destabilization and mass-wasting during sublimation of CO2 frost in the spring. While there is evidence for springtime modification of these features, our analysis of early springtime images reveals that over 80% of the new alcoves are visible underneath the CO2 frost. Thus, we present an alternative hypothesis that formation of new alcoves and fans occurs prior to CO2 deposition. We propose that fans and alcoves form primarily by aeolian processes in the mid- to late summer, through a sequence of aeolian deposition on the slipface, over-steepening, failure, and dry granular flow. An aeolian origin is supported by the orientations of the alcoves, which are consistent with recent wind directions. Furthermore, morphologically similar but much smaller alcoves form on terrestrial dune slipfaces, and the size differences between the terrestrial and Martian features may reflect cohesion in the near-subsurface of the Martian features. The size and preservation of the largest alcoves on the Martian slipfaces also support the presence of an indurated surface layer; thus, new alcoves might be sites of early spring CO2 sublimation and secondary mass-wasting because they act as a window to looser, less indurated materials that warm up more quickly in the spring.
NASA Astrophysics Data System (ADS)
Gaume, Johan; Löwe, Henning; Tan, Shurun; Tsang, Leung
2017-09-01
We have conducted discrete element simulations (pfc3d) of very loose, cohesive, granular assemblies with initial configurations which are drawn from Baxter's sticky hard sphere (SHS) ensemble. The SHS model is employed as a promising auxiliary means to independently control the coordination number zc of cohesive contacts and particle volume fraction ϕ of the initial states. We focus on discerning the role of zc and ϕ for the elastic modulus, failure strength, and the plastic consolidation line under quasistatic, uniaxial compression. We find scaling behavior of the modulus and the strength, which both scale with the cohesive contact density νc=zcϕ of the initial state according to a power law. In contrast, the behavior of the plastic consolidation curve is shown to be independent of the initial conditions. Our results show the primary control of the initial contact density on the mechanics of cohesive granular materials for small deformations, which can be conveniently, but not exclusively explored within the SHS-based assembling procedure.
Zhao, Jingxin; Liu, Xia; Wang, Meifang
2015-10-01
Using cross-sectional data from rural left-behind children aged 10-17 years in the Henan Province of China, the present study examined the roles of father-child cohesion, mother-child cohesion, and friend companionship in emotional adaptation (loneliness, depression, and life satisfaction) among children left behind by both of their rural-to-urban migrant parents compared to those with only a migrating father. The results indicated that the children with two migrating parents were disadvantaged according to their demonstration of depression but not in loneliness or life satisfaction. Both parent-child cohesion and friend companionship were directly associated with, to varying extents, the left-behind children's emotional outcomes. Moreover, friend companionship moderated the association between father-child cohesion and emotional outcomes among children with two migrating parents, but the moderating effects of friend companionship did not exist among children with only a migrating father. The implications of these findings for interventions directed at left-behind children are discussed. Copyright © 2015 Elsevier Ltd. All rights reserved.
Resilience and Vulnerability to the Psychological Harm From Flooding: The Role of Social Cohesion.
Greene, Giles; Paranjothy, Shantini; Palmer, Stephen R
2015-09-01
We examined the role of social cohesion as a component of vulnerability and resilience to the psychological distress of flooding. A survey collected data from 2238 individuals living in flood-affected areas of England (South Yorkshire and Worcestershire) in 2007. We used Bayesian structural equation modeling to assess factors relating to the latent variables of resilience (years in area, family nearby, and social cohesion) and vulnerability (disruption of essential services, flood risk, and previous flood experience). Flooding was strongly associated with poor mental health; however, resilience factors (associated with the ability to cope with natural disasters), but not vulnerability, were strongly associated with a reduction in psychological distress. Resilience and social cohesion were important influences on the risk of developing poor mental health following flooding. Increasing resilience of communities by strengthening social cohesion through measures that increase civic participation and changing land use should be considered as potentially inexpensive and effective defenses against avoidable mental harm that will result from increased climate instability.
Neighborhood Disorder, Perceived Social Cohesion, and Social Participation Among Older Americans.
Latham, Kenzie; Clarke, Philippa J
2016-08-01
This research explores whether physical neighborhood disorder or perceived social cohesion is associated with participation in social activities among older Americans (age 65+). Using the first wave of the National Health & Aging Trends Study (NHATS; N = 6,383), a series of logistic regression models were created to assess the odds of participation. Low social cohesion was associated with decreased odds of visiting friends and family (odds ratio [OR] = 0.65; 95% confidence interval [CI] = [0.52, 0.82]) and participating in organizations (OR = 0.68; 95% CI = [0.53, 0.88]). Presence of neighborhood disorder was associated with decreased odds of visiting friends and family (OR = 0.62; 95% CI = [0.47, 0.82]), participating in organizations (OR = 0.66; 95% CI = [0.48, 0.89]), and going out for enjoyment (OR = 0.68; 95% CI = [0.53, 0.86]). Physical capacity and activity value moderated the relationship between neighborhood disorder/cohesion and attending religious services. Improving neighborhood disorder and social cohesion may increase social participation among older adults.
Perceived Neighborhood Safety, Social Cohesion, and Psychological Health of Older Adults.
Choi, Yeon Jin; Matz-Costa, Christina
2018-01-18
We aimed to investigate the interactive effects of perceived neighborhood safety and social cohesion on the psychological health of older adults with and without functional impairments. This cross-sectional study included 13,897 community-dwelling older adults (aged 65 years and older) from the 2011-2012 California Health Interview Survey (CHIS). Hypotheses were tested using weighted moderated ordinary least squared regression analysis. Perceived neighborhood safety was significantly associated with psychological health regardless of respondents' physical functioning, although the effect was greater among older adults with functional limitations. Perceived social cohesion, however, was only significantly related to psychological health among those with functional limitations. Among physically impaired respondents, social cohesion buffered the ill-effect of an unsafe neighborhood on psychological health. Findings suggest that efforts to promote perceived neighborhood safety and social cohesion are essential to the well-being of older adults. Special attention should be paid to older adults with functional limitations, who appear to be more vulnerable to the negative effects of neighborhood environments.
A Cohesive Zone Approach for Fatigue-Driven Delamination Analysis in Composite Materials
NASA Astrophysics Data System (ADS)
Amiri-Rad, Ahmad; Mashayekhi, Mohammad
2017-08-01
A new model for prediction of fatigue-driven delamination in laminated composites is proposed using cohesive interface elements. The presented model provides a link between cohesive elements damage evolution rate and crack growth rate of Paris law. This is beneficial since no additional material parameters are required and the well-known Paris law constants are used. The link between the cohesive zone method and fracture mechanics is achieved without use of effective length which has led to more accurate results. The problem of unknown failure path in calculation of the energy release rate is solved by imposing a condition on the damage model which leads to completely vertical failure path. A global measure of energy release rate is used for the whole cohesive zone which is computationally more efficient compared to previous similar models. The performance of the proposed model is investigated by simulation of well-known delamination tests and comparison against experimental data of the literature.
Leadership for the Nineties: Development of Training and Research Instruments
1990-07-01
1980). The will to fight. In S. C. Sarkesian (Ed.), Combat effectiveness: Cohesion, stress and the volunteer military. (pp. 186-212). Headquarters...Institute for the Bahavioral and Social Sciences. Oliver, L. W. (1988a). The relationship of group cohesion to group performance: A research integration...Sarkesian (Ed.), Combat effectiveness: Cohesion, stress and the volunteer military: Vol. 9 (pp. 57-93). Beverly Hills, CA: Sage Publications. Sterling, B.S
ERIC Educational Resources Information Center
Gruber, Joseph J.; Gray, Gary R.
1982-01-01
A study analyzed team cohesion perceptions of 515 male varsity basketball players (10 to 22 years of age) to determine if factors influencing team cohesion were a function of competitive intensity or of the importance of individual players to their team. Players with the most game playing time were more satisfied than those with less playing time.…
1982-09-01
Fight Combat Effectiveness Organizational Assessment Package Morale Combat Effectiveness Model Cohesion Leadership 20. AIISTRACT (COe/Mie do ,eae aide If...of combat readiness. The major psychosocial dimensions which contribute to combat effectiveness of a military unit (morale leadership , cohesion, and...psychosocial dimensions in the combat effectiveness model (morale, leadership , and cohesion) in addition to training, logistics, alienation, and work group
Numerical model of glulam beam delamination in dependence on cohesive strength
NASA Astrophysics Data System (ADS)
Kawecki, Bartosz; Podgórski, Jerzy
2018-01-01
This paper presents an attempt of using a finite element method for predicting delamination of a glue laminated timber beam through a cohesive layer. There were used cohesive finite elements, quadratic stress damage initiation criterion and mixed mode energy release rate failure model. Finite element damage was equal to its complete stiffness degradation. Timber material was considered to be an orthotropic with plastic behaviour after reaching bending limit.
Potential System Vulnerabilities of a Network Enabled Force
2004-09-01
of trust in information, loss of context and awareness of others’ needs and reduction of social cohesion . Science - (more specifically systems...and Technology Damaging Social Cohesion NCW champions the concept of dispersed forces as a means to generate effects through approaches other than...Mission Grouping Damaging Social Cohesion This is a slight variation on the vulnerability expressed in 3.9.6 above. If we have agility in mission
[Team cohesiveness: opinions of a group of primary health care professionals from Salamanca].
González, F J; de Cabo, A; Morán, M J; Manzano, J M
1993-04-01
To assess the view of a group of Primary care professionals on their level of perception of group cohesiveness in their teams' work dynamic. A descriptive and sectional study. Four urban health centres in Salamanca with a recognised teaching activity. Both health professionals and those outside the Health Service, working in Primary Care, who had been members of their teams for more than a year (N = 90). Descriptive statistics and "Chi squared" tests were employed. 72%. A high level of agreement on the need for team work (95.23%). They perceived their group cohesiveness as being very low (84.21% affirmed that they encounter problems of cohesiveness). The main statements concerning this lack of cohesiveness were: "lack of common objectives" (25.5%), "intolerance between workers" (20.13%), "work not shared" (19.46%) and "the taking of decisions individually" (19.44%). The main causes given were: lack of support from Management (23.74%) and too little training for team work (21.58%). There is a high degree of conviction that the team work model is the most efficacious way of developing Primary Care. However in three of the four teams questioned, there were serious problems preventing the teams' reaching an adequate level of group cohesiveness.
Filho, Edson; Tenenbaum, Gershon; Yang, Yanyun
2015-01-01
A nomological network on team dynamics in sports consisting of a multiframework perspective is introduced and tested. The aim was to explore the interrelationship among cohesion, team mental models (TMMs), collective efficacy (CE) and perceived performance potential (PPP). Three hundred and forty college-aged soccer players representing 17 different teams (8 female and 9 male) participated in the study. They responded to surveys on team cohesion, TMMs, CE and PPP. Results are congruent with the theoretical conceptualisation of a parsimonious view of team dynamics in sports. Specifically, cohesion was found to be an exogenous variable predicting both TMMs and CE beliefs. TMMs and CE were correlated and predicted PPP, which in turn accounted for 59% of the variance of objective performance scores as measured by teams' season record. From a theoretical standpoint, findings resulted in a parsimonious view of team dynamics, which may represent an initial step towards clarifying the epistemological roots and nomological network of various team-level properties. From an applied standpoint, results suggest that team expertise starts with the establishment of team cohesion. Following the establishment of cohesiveness, teammates are able to advance team-related schemas and a collective sense of confidence. Limitations and key directions for future research are outlined.
Displacement, county social cohesion, and depression after a large-scale traumatic event.
Lê, Félice; Tracy, Melissa; Norris, Fran H; Galea, Sandro
2013-11-01
Depression is a common and potentially debilitating consequence of traumatic events. Mass traumatic events cause wide-ranging disruptions to community characteristics, influencing the population risk of depression. In the aftermath of such events, population displacement is common. Stressors associated with displacement may increase risk of depression directly. Indirectly, persons who are displaced may experience erosion in social cohesion, further exacerbating their risk for depression. Using data from a population-based cross-sectional survey of adults living in the 23 southernmost counties of Mississippi (N = 708), we modeled the independent and joint relations of displacement and county-level social cohesion with depression 18-24 months after Hurricane Katrina. After adjustment for individual- and county-level socio-demographic characteristics and county-level hurricane exposure, joint exposure to both displacement and low social cohesion was associated with substantially higher log-odds of depression (b = 1.34 [0.86-1.83]). Associations were much weaker for exposure only to low social cohesion (b = 0.28 [-0.35-0.90]) or only to displacement (b = 0.04 [-0.80-0.88]). The associations were robust to additional adjustment for individually perceived social cohesion and social support. Addressing the multiple, simultaneous disruptions that are a hallmark of mass traumatic events is important to identify vulnerable populations and understand the psychological ramifications of these events.
Group cohesion in foraging meerkats: follow the moving 'vocal hot spot'.
Gall, Gabriella E C; Manser, Marta B
2017-04-01
Group coordination, when 'on the move' or when visibility is low, is a challenge faced by many social living animals. While some animals manage to maintain cohesion solely through visual contact, the mechanism of group cohesion through other modes of communication, a necessity when visual contact is reduced, is not yet understood. Meerkats ( Suricata suricatta ), a small, social carnivore, forage as a cohesive group while moving continuously. While foraging, they frequently emit 'close calls', soft close-range contact calls. Variations in their call rates based on their local environment, coupled with individual movement, produce a dynamic acoustic landscape with a moving 'vocal hotspot' of the highest calling activity. We investigated whether meerkats follow such a vocal hotspot by playing back close calls of multiple individuals to foraging meerkats from the front and back edge of the group simultaneously. These two artificially induced vocal hotspots caused the group to spatially elongate and split into two subgroups. We conclude that meerkats use the emergent dynamic call pattern of the group to adjust their movement direction and maintain cohesion. Our study describes a highly flexible mechanism for the maintenance of group cohesion through vocal communication, for mobile species in habitats with low visibility and where movement decisions need to be adjusted continuously to changing environmental conditions.
Salahuddin, Meliha; Nehme, Eileen; Ranjit, Nalini; Kim, Young-Jae; Oluyomi, Abiodun O; Dowdy, Diane; Lee, Chanam; Ory, Marcia; Hoelscher, Deanna M
2016-12-01
The role of parents' perceptions of the neighborhood environment in determining children's active commuting to and from school (ACS) is understudied. This study examined the association between parents' perceptions of neighborhood social cohesion, perceived neighborhood safety, and their children's ACS. This cross-sectional analysis (n = 857 from 81 elementary schools in Texas) examined baseline data from the Texas Childhood Obesity Prevention Policy Evaluation project. Participants had a mean age of 9.6 (0.6) years, and 50% were girls. Mixed effects logistic regression models were used to assess gender-stratified associations between parent's perceived social cohesion and children's ACS and their perception of neighborhood safety. A positive significant association was observed between levels of perceived social cohesion and children's ACS for boys (P = 0.047); however, an inverse significant association was observed among girls (P = 0.033). Parents of boys living in neighborhoods with medium to high social cohesion were more likely to perceive their neighborhood as safe compared with parents living in neighborhoods with low social cohesion, though nonsignificant. Perceived neighborhood safety for walking and biking was associated with greater ACS among boys (P = 0.003). Our study findings indicate that both social and physical environments are important factors in determining ACS among boys.
Perceived neighborhood social cohesion and stroke.
Kim, Eric S; Park, Nansook; Peterson, Christopher
2013-11-01
Research in the last three decades has shown that negative neighborhood factors such as neighborhood violence, noise, traffic, litter, low neighborhood socioeconomic status, and poor air quality increase the risk of poor health. Fewer studies have examined the potential protective effect that neighborhood factors can have on health, particularly stroke. We examined whether higher perceived neighborhood social cohesion was associated with lower stroke incidence after adjusting for traditional risk and psychological factors that have been linked with stroke risk. Prospective data from the Health and Retirement Study--a nationally representative panel study of American adults over the age of 50--were used. Analyses were conducted on a subset of 6740 adults who were stroke-free at baseline. Analyses adjusted for chronic illnesses and relevant sociodemographic, behavioral, and psychosocial factors. Over a four-year follow-up, higher perceived neighborhood social cohesion was associated with a lower risk of stroke. Each standard deviation increase in perceived neighborhood social cohesion was associated with a multivariate-adjusted odds ratio (O.R.) of 0.85 for stroke incidence (95% CI, 0.75-0.97, p < 0.05). The effect of perceived neighborhood social cohesion remained significant after adjusting for a comprehensive set of risk factors. Therefore, perceived neighborhood social cohesion plays an important role in protecting against stroke. Copyright © 2013 Elsevier Ltd. All rights reserved.
NASA Astrophysics Data System (ADS)
Komatsu, Taro
2014-05-01
This study seeks to understand whether and how decentralised school governance in Bosnia and Herzegovina (BiH) enhances the schools' role of promoting social cohesion. This includes increasing "horizontal" trust among different ethnic groups and "vertical" trust between civilians and public institutes. The study examined secondary school leaders' perceptions regarding school board influence on social cohesion policies and practices, their interactions with school board members, and their accountability to the school-based governing body. The results show that school leaders and school boards, supposedly representing the interests of local stakeholders, did not appear to be actively engaged in the deliberate process of promoting social cohesion. While school directors tended to view themselves as being independent from the school boards, ethnically diverse school boards provided important support to proactive school leaders for their inter-group activities. Given that the central level is not providing initiatives to promote social cohesion and that BiH citizens appear to generally support social cohesion, decentralised school governance has the potential to improve social trust from the bottom up. To promote participatory school governance, the study recommends that BiH school leaders should be provided with opportunities to re-examine and redefine their professional accountability and to assist local stakeholders to improve their involvement in school governance.
Anyan, Frederick; Hjemdal, Odin
2017-04-05
This cross-sectional study investigated the relation of sociocultural prescriptions of gender role socializations to differences in stress at home and to anxiety and depressive symptoms for adolescent girls and boys, with family cohesion as a mediator. A total of 244 boys and 285 girls aged 13-17 years recruited from Accra, Ghana completed the Short Mood Feeling Questionnaire, Spielberger State Anxiety Inventory, Stress of Home Life and Family Cohesion self-report scales in April 2015. In each sample, two mediation analyses were conducted using Structural Equation Modelling. Exposure to stress at home that was perceived to result from sociocultural prescriptions of gender role norms largely accounted for anxiety and depressive symptoms among girls, whereas this relation was non-significant among boys. Significant indirect relations through low family cohesion to anxiety symptoms were observed for girls and boys but not to depressive symptoms for boys. These findings suggest that differences in gender role socializations at home may account for individual differences in associations between exposure to stress at home and anxiety and depressive symptoms as well as explain the differential indirect relations through low family cohesion. Improving family cohesion while reducing stress at home may contribute to reducing stress and thus anxiety and depressive symptoms.
Lim, Jung-Won; Shon, En-Jung
Spouses' ability to care for survivors can be particularly challenging because patients and spouses are interdependent and mutually influence one another. Family functioning such as family cohesion and communication may play a primary role in improving the health-related quality of life (HRQOL) of couples, given that cancer can influence family dynamics. The aims of this study were to investigate the mediating effect of family communication on the relationship between family cohesion and HRQOL and examine the moderating effect of sex on this relationship among cancer survivor-spouse dyads. A total of 91 cancer survivors with a diagnosis of breast, colorectal, or prostate cancer and their spouses were recruited from the University Hospital Registry in Cleveland, Ohio. The dyadic data were analyzed using structural equation modeling with the actor-partner interdependence mediation model. Findings demonstrated that the spouses' own perceived family communication mediated the associations between their own family cohesion and physical HRQOL and between the survivors' family cohesion and physical HRQOL. The spouse actor effects between family communication and HRQOL significantly differed by sex. Enhancing family cohesion and communication within the family can improve the spouses' HRQOL. Findings regarding sex differences serve as a rationale for gender-based approaches to improving HRQOL in survivorship care in the family context. Couple- and/or family-based interventions should be designed to enhance family cohesion and improve family communication skills for effective adjustments within couples and families. Supportive care within the family context can be promoted to address the diverse challenges of survivorship care.
Social cohesion and the smoking behaviors of adults living with children.
Alcalá, Héctor E; Sharif, Mienah Z; Albert, Stephanie L
2016-02-01
The smoking behavior of adults can negatively impact children through exposure to environmental tobacco smoke and by modeling this unhealthy behavior. Little research has examined the role of the social environment in smoking behaviors of adults living with children. The present study specifically analyzed the relationship between social cohesion and smoking behaviors of adults living with children. Data from the 2009 California Health Interview Survey, a random-digit dial cross-sectional survey of California Adults, were used. Adults living with children reported their levels of social cohesion and smoking behaviors (N=13,978). Logistic regression models were used to predict odds of being a current smoker or living in a household in which smoking was allowed, from social cohesion. Overall, 13% of the sample was current smokers and 3.74% lived in households in which smoking was allowed. Logistic regression models showed that each one-unit increase in social cohesion is associated with reduced odds of being a current smoker (AOR=0.92; 95% CI=0.85-0.99) and reduced odds of living in a household in which smoking is allowed (AOR=0.84; 95% CI=0.75-0.93), after controlling for sociodemographic characteristics. Among adults living with children, higher social cohesion is associated with a lower likelihood of both being and smoker and living in a home where smoking is allowed. Thus, future research is needed to better understand mechanisms that explain the relationship between social cohesion and smoking-related behavior in order to prevent smoking-related health consequences and smoking initiation among children and adults. Copyright © 2015 Elsevier Ltd. All rights reserved.
Shen, Hong-Bin
2011-01-01
Modern science of networks has brought significant advances to our understanding of complex systems biology. As a representative model of systems biology, Protein Interaction Networks (PINs) are characterized by a remarkable modular structures, reflecting functional associations between their components. Many methods were proposed to capture cohesive modules so that there is a higher density of edges within modules than those across them. Recent studies reveal that cohesively interacting modules of proteins is not a universal organizing principle in PINs, which has opened up new avenues for revisiting functional modules in PINs. In this paper, functional clusters in PINs are found to be able to form unorthodox structures defined as bi-sparse module. In contrast to the traditional cohesive module, the nodes in the bi-sparse module are sparsely connected internally and densely connected with other bi-sparse or cohesive modules. We present a novel protocol called the BinTree Seeking (BTS) for mining both bi-sparse and cohesive modules in PINs based on Edge Density of Module (EDM) and matrix theory. BTS detects modules by depicting links and nodes rather than nodes alone and its derivation procedure is totally performed on adjacency matrix of networks. The number of modules in a PIN can be automatically determined in the proposed BTS approach. BTS is tested on three real PINs and the results demonstrate that functional modules in PINs are not dominantly cohesive but can be sparse. BTS software and the supporting information are available at: www.csbio.sjtu.edu.cn/bioinf/BTS/. PMID:22140454
Cramm, J M; van Dijk, H M; Nieboer, A P
2013-04-01
We aimed to investigate whether social capital (obtaining support through indirect ties such as from neighbors) and social cohesion (interdependencies among neighbors) within neighborhoods positively affect the well-being of older adults. This cross-sectional study included 945/1440 (66 % response rate) independently living older adults (aged >70 years) in Rotterdam. We fitted a hierarchical random-effects model to account for the hierarchical structure of the study design: 945 older adults (level 1) nested in 72 neighborhoods (level 2). Univariate analyses showed that being born in the Netherlands, house ownership, education, income, social capital of individuals, neighborhood security, neighborhood services, neighborhood social capital, and neighborhood social cohesion were significantly related to the well-being of older adults. Multilevel analyses showed that social capital of individuals, neighborhood services, neighborhood social capital, and neighborhood social cohesion predicted the well-being of older adults. Single and poor older adults reported lower well-being than did better-off and married older adults. However, the effects of marital status and income were mediated by neighborhood services, social capital, and social cohesion. Neighborhood services, social capital and social cohesion may act as buffer against the adverse effects of being single and poor on the well-being of older adults. The results of this study support the importance of social capital of individuals, as well as social capital within the neighborhood and social cohesion within the neighborhood for well-being of older adults. The well-being of older adults may also be enhanced through the improvement of quality of neighborhood services.
Social Cohesion and the Smoking Behaviors of Adults Living with Children
Sharif, Mienah Z.; Albert, Stephanie L.
2015-01-01
Introduction The smoking behavior of adults can negatively impact children through exposure to environmental tobacco smoke and by modeling this unhealthy behavior. Little research has examined the role of the social environment in smoking behaviors of adults living with children. The present study specifically analyzed the relationship between social cohesion and smoking behaviors of adults living with children. Methods Data from the 2009 California Health Interview Survey, a random-digit dial cross-sectional survey of California Adults, were used. Adults living with children reported their levels of social cohesion and smoking behaviors (N=13,978). Logistic regression models were used to predict odds of being a current smoker or living in a household in which smoking was allowed, from social cohesion. Results Overall, 13% of the sample was current smokers and 3.74% lived in households in which smoking was allowed. Logistic regression models showed that each one-unit increase in social cohesion is associated with reduced odds of being a current smoker (AOR= 0.92; 95% CI= 0.85–0.99) and reduced odds of living in a household in which smoking is allowed (AOR= 0.84; 95% CI= 0.75–0.93), after controlling for sociodemographic characteristics. Conclusions Among adults living with children, higher social cohesion is associated with a lower likelihood of both being and smoker and living in a home where smoking is allowed. Thus, future research is needed to better understand mechanisms that explain the relationship between social cohesion and smoking-related behavior in order to prevent smoking-related health consequences and smoking initiation among children and adults. PMID:26562680
Cramm, Jane M; van Dijk, Hanna M; Nieboer, Anna P
2013-02-01
We aimed to investigate whether social capital (obtaining support through indirect ties such as from neighbors) and social cohesion (interdependencies among neighbors) within neighborhoods positively affect the well being of older adults. This cross-sectional study included 945 of 1,440 (66% response rate) independently living older adults (aged ≥70 years) in Rotterdam. We fitted a hierarchical random effects model to account for the hierarchical structure of the study design: 945 older adults (Level 1) nested in 72 neighborhoods (Level 2). Univariate analyses showed that being born in the Netherlands, house ownership, education, income, social capital of individuals, neighborhood security, neighborhood services, neighborhood social capital, and neighborhood social cohesion were significantly related to the well being of older adults. Multilevel analyses showed that social capital of individuals, neighborhood services, neighborhood social capital, and neighborhood social cohesion predicted the well being of older adults. Single and poor older adults reported lower well being than did better off and married older adults. However, the effects of marital status and income were mediated by neighborhood services, social capital, and social cohesion. Neighborhood services, social capital, and social cohesion may act as buffer against the adverse effects of being single and poor on the well being of older adults. The results of this study support the importance of social capital of individuals, as well as social capital within the neighborhood and social cohesion within the neighborhood for well being of older adults. The well being of older adults may also be enhanced through the improvement of quality of neighborhood services.
Cohesive and coherent connected speech deficits in mild stroke.
Barker, Megan S; Young, Breanne; Robinson, Gail A
2017-05-01
Spoken language production theories and lesion studies highlight several important prelinguistic conceptual preparation processes involved in the production of cohesive and coherent connected speech. Cohesion and coherence broadly connect sentences with preceding ideas and the overall topic. Broader cognitive mechanisms may mediate these processes. This study aims to investigate (1) whether stroke patients without aphasia exhibit impairments in cohesion and coherence in connected speech, and (2) the role of attention and executive functions in the production of connected speech. Eighteen stroke patients (8 right hemisphere stroke [RHS]; 6 left [LHS]) and 21 healthy controls completed two self-generated narrative tasks to elicit connected speech. A multi-level analysis of within and between-sentence processing ability was conducted. Cohesion and coherence impairments were found in the stroke group, particularly RHS patients, relative to controls. In the whole stroke group, better performance on the Hayling Test of executive function, which taps verbal initiation/suppression, was related to fewer propositional repetitions and global coherence errors. Better performance on attention tasks was related to fewer propositional repetitions, and decreased global coherence errors. In the RHS group, aspects of cohesive and coherent speech were associated with better performance on attention tasks. Better Hayling Test scores were related to more cohesive and coherent speech in RHS patients, and more coherent speech in LHS patients. Thus, we documented connected speech deficits in a heterogeneous stroke group without prominent aphasia. Our results suggest that broader cognitive processes may play a role in producing connected speech at the early conceptual preparation stage. Copyright © 2017 Elsevier Inc. All rights reserved.
Corporal Punishment and Child Aggression: Ethnic-Level Family Cohesion as a Moderator.
Lee, Yoona; Watson, Malcolm W
2017-04-01
Ethnicity has been examined as a putative moderator between parents' use of corporal punishment and children's externalizing behaviors. Yet, the reasons for this potential ethnic-level moderator have not been fully examined. The primary objective of this study was to examine whether the effect of corporal punishment on aggression is ethnic-specific using major racial groups inside and outside the U.S. samples and how the mean levels of cohesion in family relationships as found in different ethnic groups moderate the association between mothers' use of corporal punishment and children's aggression. A total of 729 mothers who had children aged 7 to 13 years were sampled from five ethnic groups (i.e., European American, African American, Hispanic American, Korean, and Chinese). Several hypotheses were tested to examine the moderating effect of ethnic-level, family cohesion on the relation of corporal punishment to children's aggression. As expected, the mean level of family cohesion was significantly different across ethnicities. Consistent results across parallel multilevel and fixed effect models showed that high corporal punishment was associated with more aggression in all ethnicities, but there was a significant variation in the association across ethnicities, and the variation was explained by ethnic-level family cohesion. There were weaker associations between corporal punishment and child aggression among ethnic groups with high family cohesion and stronger associations among ethnic groups with low family cohesion. Ethnic/cultural variation in this study emphasizes the importance of understanding family environment of diverse ethnic groups when evaluating the influence of corporal punishment on child behavior in different ethnic/cultural contexts.
Nishikawa, Mari; Suzuki, Mariko; Sprague, David S
2014-07-01
Understanding cohesion among individuals within a group is necessary to reveal the social system of group-living primates. Japanese macaques (Macaca fuscata) are female-philopatric primates that reside in social groups. We investigated whether individual activity and social factors can affect spatio-temporal cohesion in wild female Japanese macaques. We conducted behavioral observation on a group, which contained 38 individuals and ranged over ca. 60 ha during the study period. Two observers carried out simultaneous focal-animal sampling of adult female pairs during full-day follows using global positioning system which enabled us to quantify interindividual distances (IIDs), group members within visual range (i.e., visual unit), and separation duration beyond visual range as indicators of cohesion among individuals. We found considerable variation in spatio-temporal group cohesion. The overall mean IID was 99.9 m (range = 0-618.2 m). The percentage of IIDs within visual range was 23.1%, within auditory range was 59.8%, and beyond auditory range was 17.1%. IIDs varied with activity; they were shorter during grooming and resting, and longer during foraging and traveling. Low-ranking females showed less cohesion than high-ranking ones. Kin females stayed nearly always within audible range. The macaques were weakly cohesive with small mean visual unit size (3.15 counting only adults, 5.99 counting all individuals). Both-sex units were the most frequently observed visual unit type when they were grooming/resting. Conversely, female units were the most frequently observed visual unit type when they were foraging. The overall mean visual separation duration was 25.7 min (range = 3-513 min). Separation duration was associated with dominance rank. These results suggest that Japanese macaques regulate cohesion among individuals depending on their activity and on social relationships; they were separated to adapt food distribution and aggregated to maintain social interactions. © 2014 Wiley Periodicals, Inc.
NASA Astrophysics Data System (ADS)
Brovchenko, Igor; Maderich, Vladimir; Jung, Kyung Tae
2015-04-01
We developed new radionuclide dispersion model that may be used in coastal areas, rivers and estuaries with non-uniform distribution of suspended and bed sediments both cohesive and non-cohesive types. Model describes radionuclides concentration in dissolved phase in water column, particulated phase on suspended sediments on each sediment class types, bed sediments and pore water. The transfer of activity between the water column and the pore water in the upper layer of the bottom sediment is governed by diffusion processes. The phase exchange between dissolved and particulate radionuclides is written in terms of desorption rate a12 (s-1) and distribution coefficient Kd,iw and Kd,ib (m3/kg) for water column and for bottom deposit, respectively. Following (Periáñez et al., 1996) the dependence of distribution coefficients is inversely proportional to the sediment particle size. For simulation of 3D circulation, turbulent diffusion and wave fields a hydrostatic model SELFE (Roland et. al. 2010) that solves Reynolds-stress averaged Navier-Stokes (RANS) equations and Wave Action transport equation on the unstructured grids was used. Simulation of suspended sediment concentration and bed sediments composition is based on (L. Pinto et. al., 2012) approach that originally was developed for non-cohesive sediments. In present study we modified this approach to include possibility of simulating mixture of cohesive and non-cohesive sediments by implementing parameterizations for erosion and deposition fluxes for cohesive sediments and by implementing flocculation model for determining settling velocity of cohesive flocs. Model of sediment transport was calibrated on measurements in the Yellow Sea which is shallow tidal basin with strongly non-uniform distribution of suspended and bed sediments. Model of radionuclide dispersion was verified on measurements of 137Cs concentration in surface water and bed sediments after Fukushima Daiichi nuclear accident. References Periáñez, R. Abril, J.M., Garcia-Leon, M. (1996). Modelling the dispersion of non-conservative radionuclides in tidal waters'Part 1: conceptual and mathematical model. Journal of Environmental Radioactivity 31 (2), 127-141 Roland, A., Y. J. Zhang, H. V. Wang, Y. Meng, Y.-C. Teng, V. Maderich, I. Brovchenko, M. Dutour-Sikiric, and U. Zanke (2012), A fully coupled 3D wave-current interaction model on unstructured grids, J. Geophys. Res., 117, C00J33 Pinto L., Fortunato A.B., Zhang Y., Oliveira A., Sancho F.E.P. (2012) Development and validation of a three-dimensional morphodynamic modelling system for non-cohesive sediments, Ocean Modell., (57-58), 1-14
Effect of air gap on apparent temperature of body wearing various sizes of T-shirt
NASA Astrophysics Data System (ADS)
Takatera, M.; Uchiyama, E.; Zhu, C.; Kim, KO; Ishizawa, H.
2017-10-01
We investigated the effect of air gap on the apparent temperature. Using the developed thermocouple fabric and a thermal manikin, we measured temperature distribution of the measuring garments due to the change of T-shirt sizes. We were able to measure the apparent temperature distribution at points near a body while wearing different sizes of T-shirts. It was observed that the temperature distribution depending on different air gap between clothing and body. The apparent temperature depends on garment size and place. The effect of air gap on apparent temperature of body was experimentally confirmed.
NASA Astrophysics Data System (ADS)
Bentley, S. J.; Keller, G. P.; Obelcz, J.; Maloney, J. M.; Xu, K.; Georgiou, I. Y.; Miner, M. D.
2016-12-01
On river deltas dominated by proximal sediment accumulation (Mississippi, Huang He, others), the delta front region is commonly dominated by rapid accumulation of cohesive fluvial sediments, and mass-wasting processes that remobilize recently deposited sediments. Mass transport is preconditioned in sediments by high water content, biogenic gas production, over steepening, and is commonly triggered by strong wave loading and other processes. This understanding is based on extensive field studies in the 1970's and 80's. Recent studies of the Mississippi River Delta Front are yielding new perspectives on these processes, in a time of anthropogenically reduced sediment loads, rising sea level, and catastrophic deltaic land loss. We have synthesized many industry data sets collected since ca. 1980, and conducted new pilot field and modeling studies of sedimentary and morphodynamic processes. These efforts have yielded several key findings that diverge from historical understanding of this dynamic setting. First, delta distributary mouths have ceased seaward progradation, ending patterns that have been documented since the 18th century. Second, despite reduced sediment supply, offshore mass transport continues, yielding vertical displacements at rates of 1 m/y. This displacement is apparently forced by wave loading from storm events of near-annual return period, rather than major hurricanes that have been the focus of most previous studies. Third, core analysis indicates that this vertical displacement is occurring along failure planes >3 m in the seabed, rather than in more recently deposited sediments closer to the sediment-water interface. These seabed morphodynamics have the potential to destabilize both nearshore navigation infrastructure, and seabed hydrocarbon infrastructure offshore. As well, these findings raise more questions regarding the future seabed evolution offshore of major river deltas, in response to anthropogenic and climatic forcing.
In Our Backyard How 3 L.A. Neighborhoods Affect Kids’ Lives
2002-02-01
neighborhood social environment are particularly important for children, including • safety • whether neighbors know each other • social cohesion —that is...families in each neighborhood reported a relatively moderate level of conflict (an average of 12 on a scale from 4 to 24). Social cohesion Social ...prevent crime. The Social Cohesion Index was developed and tested by researchers at Harvard and the University of Chicago to assess the social
Family environment patterns in families with bipolar children.
Belardinelli, Cecilia; Hatch, John P; Olvera, Rene L; Fonseca, Manoela; Caetano, Sheila C; Nicoletti, Mark; Pliszka, Steven; Soares, Jair C
2008-04-01
We studied the characteristics of family functioning in bipolar children and healthy comparison children. We hypothesized that the family environment of bipolar children would show greater levels of dysfunction as measured by the Family Environment Scale (FES). We compared the family functioning of 36 families that included a child with DSM-IV bipolar disorder versus 29 comparison families that included only healthy children. All subjects and their parents were assessed with the K-SADS-PL interview. The parents completed the FES to assess their current family functioning. Multivariate analysis of variance was used to compare the family environment of families with and without offspring with bipolar disorder. Parents of bipolar children reported lower levels of family cohesion (p<0.001), expressiveness (p=0.005), active-recreational orientation (p<0.001), intellectual-cultural orientation (p=0.04) and higher levels of conflict (p<0.001) compared to parents with no bipolar children. Secondary analyses within the bipolar group revealed lower levels of organization (p=0.031) and cohesion (p=0.014) in families where a parent had a history of mood disorders compared to families where parents had no history of mood disorders. Length of illness in the affected child was inversely associated with family cohesion (r=-0.47, p=0.004). Due to the case-control design of the study, we cannot comment on the development of these family problems or attribute their cause specifically to child bipolar disorder. Families with bipolar children show dysfunctional patterns related to interpersonal interactions and personal growth. A distressed family environment should be addressed when treating children with bipolar disorder.
Income inequality within urban settings and depressive symptoms among adolescents.
Pabayo, Roman; Dunn, Erin C; Gilman, Stephen E; Kawachi, Ichiro; Molnar, Beth E
2016-10-01
Although recent evidence has shown that area-level income inequality is related to increased risk for depression among adults, few studies have tested this association among adolescents. We analysed the cross-sectional data from a sample of 1878 adolescents living in 38 neighbourhoods participating in the 2008 Boston Youth Survey. Using multilevel linear regression modelling, we: (1) estimated the association between neighbourhood income inequality and depressive symptoms, (2) tested for cross-level interactions between sex and neighbourhood income inequality and (3) examined neighbourhood social cohesion as a mediator of the relationship between income inequality and depressive symptoms. The association between neighbourhood income inequality and depressive symptoms varied significantly by sex, with girls in higher income inequality neighbourhood reporting higher depressive symptom scores, but not boys. Among girls, a unit increase in Gini Z-score was associated with more depressive symptoms (β=0.38, 95% CI 0.28 to 0.47, p=0.01) adjusting for nativity, neighbourhood income, social cohesion, crime and social disorder. There was no evidence that the association between income inequality and depressive symptoms was due to neighbourhood-level differences in social cohesion. The distribution of incomes within an urban area adversely affects adolescent girls' mental health; future work is needed to understand why, as well as to examine in greater depth the potential consequences of inequality for males, which may have been difficult to detect here. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/
Effects of Cohesive Sediment on Estuarine Morphology in Laboratory Scale Experiments
NASA Astrophysics Data System (ADS)
Braat, L.; Leuven, J.; Lokhorst, I.; Kleinhans, M. G.
2017-12-01
Mud plays a major role in forming and filling of river estuaries. River estuaries are typically build of sand and flanked by mudflats, which affect channel-shoal dynamics on time scales of centuries to millennia. In our research we aim to study the effects of mud on the shape and evolution of estuaries and where the largest effects occur. Recently a 20 m by 3 m flume (the Metronome) was developed at Utrecht University for tidal experiments. Complete estuaries are simulated in the Metronome by driving tidal flow by periodically tilting of the flume to counteract scaling problems. To simulate the effects of cohesive mud we supply nutshell grains to the system together with the river discharge. Three scenarios were tested, one with only sand, one with a low supply concentration of nutshell and one with a high concentration (left to right in figure).Estuaries that developed from an initial convergent shape are self-formed through bank erosion, continuous channel-shoal migration and bar and mud flat sedimentation (figure shows development over 15000 tilting cycles). The cohesive sediment deposits occur mainly on bars, but also on the flanks of the estuary and in abandoned channels. Due to its different erosional and depositional characteristics, the nutshell increases the elevation of the bars, which reduces storage and ebb-dominance and causes reduction of bar mobility and short cuts. These results agree with numerical model results. The large-scale effect is less widening of the estuary in the presence of mud and a decrease in channel-shoal migration, suggesting that mud confines estuary width in a similar manner as river floodplains.
NASA Technical Reports Server (NTRS)
Cole, Bjorn; Chung, Seung H.
2012-01-01
One of the challenges of systems engineering is in working multidisciplinary problems in a cohesive manner. When planning analysis of these problems, system engineers must tradeoff time and cost for analysis quality and quantity. The quality is associated with the fidelity of the multidisciplinary models and the quantity is associated with the design space that can be analyzed. The tradeoff is due to the resource intensive process of creating a cohesive multidisciplinary system model and analysis. Furthermore, reuse or extension of the models used in one stage of a product life cycle for another is a major challenge. Recent developments have enabled a much less resource-intensive and more rigorous approach than handwritten translation scripts or codes of multidisciplinary models and their analyses. The key is to work from a core system model defined in a MOF-based language such as SysML and in leveraging the emerging tool ecosystem, such as Query-View- Transform (QVT), from the OMG community. SysML was designed to model multidisciplinary systems and analyses. The QVT standard was designed to transform SysML models. The Europa Hability Mission (EHM) team has begun to exploit these capabilities. In one case, a Matlab/Simulink model is generated on the fly from a system description for power analysis written in SysML. In a more general case, a symbolic mathematical framework (supported by Wolfram Mathematica) is coordinated by data objects transformed from the system model, enabling extremely flexible and powerful tradespace exploration and analytical investigations of expected system performance.
NASA Technical Reports Server (NTRS)
Cole, Bjorn; Chung, Seung
2012-01-01
One of the challenges of systems engineering is in working multidisciplinary problems in a cohesive manner. When planning analysis of these problems, system engineers must trade between time and cost for analysis quality and quantity. The quality often correlates with greater run time in multidisciplinary models and the quantity is associated with the number of alternatives that can be analyzed. The trade-off is due to the resource intensive process of creating a cohesive multidisciplinary systems model and analysis. Furthermore, reuse or extension of the models used in one stage of a product life cycle for another is a major challenge. Recent developments have enabled a much less resource-intensive and more rigorous approach than hand-written translation scripts between multi-disciplinary models and their analyses. The key is to work from a core systems model defined in a MOF-based language such as SysML and in leveraging the emerging tool ecosystem, such as Query/View/Transformation (QVT), from the OMG community. SysML was designed to model multidisciplinary systems. The QVT standard was designed to transform SysML models into other models, including those leveraged by engineering analyses. The Europa Habitability Mission (EHM) team has begun to exploit these capabilities. In one case, a Matlab/Simulink model is generated on the fly from a system description for power analysis written in SysML. In a more general case, symbolic analysis (supported by Wolfram Mathematica) is coordinated by data objects transformed from the systems model, enabling extremely flexible and powerful design exploration and analytical investigations of expected system performance.
Erosion of a wet/dry granular interface
NASA Astrophysics Data System (ADS)
Jop, Pierre; Lefebvre, Gautier
2013-04-01
To model the dynamic of landslides, the evolution of the interface between the erodible ground and the flowing material is still studied experimentally or numerically (ie. Mangeney et al. 2010, Iverson 2012). In some cases, the basal material is more cohesive than the flowing one. Such situation arises for example due to cementation or humidity. What are the exchange rates between these phases? What is the coupling between the evolution of the interface and the flow? We studied the erosion phenomenon and performed laboratory experiments to focus on the interaction between a cohesive unsaturated granular material and a dry granular flow. Both materials were spherical grains, the cohesion being induced by adding a given mass of liquid to the grains. Two configurations were explored: a circular aggregate submitted to a dry flow in a rotating drum, and a granular flow eroding a wet granular pile. First, we focused on the influence of the cohesion, controlled by the liquid properties, such as the surface tension and the viscosity. Then the flow characteristics were modified by varying the grain size and density. These results allowed us to present a model for the erosion mechanisms, based on the flow and fluid properties. The main results are the need to take into account the whole probability distribution the stress applied on the wet grains and that both the surface tension and the viscosity are important since they play a different roles. The latter is mainly responsible of the time scale of the dynamic of a wet grain, while the former acts as a threshold on the force distribution. In the second configuration, we could also control the inclination of the slope. This system supported the previous model and moreover revealed an interface instability, leading the formation of steep steps, which is a reminiscence of the cyclic-steps observed during river-channel incision (Parker and Izumi 2000). We will present the dynamics of such granular steps. [1] Mangeney, A., O. Roche, O. Hungr, N. Mangold, G. Faccanoni, and A. Lucas (2010), Erosion and mobility in granular collapse over sloping beds, J. Geophys. Res., 115, F03040, doi:10.1029/2009JF001462. [2] Iverson, R. M. (2012), Elementary theory of bed-sediment entrainment by debris flows and avalanches, J. Geophys. Res., 117, F03006, doi:10.1029/2011JF002189. [3] Parker G.and Izumi N., Purely erosional cyclic and solitary steps created by flow over a cohesive bed, J. Fluid Mech. (2000), vol. 419, pp. 203-238.
Combined effect of moisture and electrostatic charges on powder flow
NASA Astrophysics Data System (ADS)
Rescaglio, Antonella; Schockmel, Julien; Vandewalle, Nicolas; Lumay, Geoffroy
2017-06-01
It is well known in industrial applications involving powders and granular materials that the relative air humidity and the presence of electrostatic charges influence drastically the material flowing properties. The relative air humidity induces the formation of capillary bridges and modify the grain surface conductivity. The presence of capillary bridges produces cohesive forces. On the other hand, the apparition of electrostatic charges due to the triboelectric effect at the contacts between the grains and at the contacts between the grains and the container produces electrostatic forces. Therefore, in many cases, the powder cohesiveness is the result of the interplay between capillary and electrostatic forces. Unfortunately, the triboelectric effect is still poorly understood, in particular inside a granular material. Moreover, reproducible electrostatic measurements are difficult to perform. We developed an experimental device to measures the ability of a powder to charge electrostatically during a flow in contact with a selected material. Both electrostatic and flow measurements have been performed in different hygrometric conditions. The correlation between the powder electrostatic properties, the hygrometry and the flowing behavior are analyzed.
Coarse-Graining of Polymer Dynamics via Energy Renormalization
NASA Astrophysics Data System (ADS)
Xia, Wenjie; Song, Jake; Phelan, Frederick; Douglas, Jack; Keten, Sinan
The computational prediction of the properties of polymeric materials to serve the needs of materials design and prediction of their performance is a grand challenge due to the prohibitive computational times of all-atomistic (AA) simulations. Coarse-grained (CG) modeling is an essential strategy for making progress on this problem. While there has been intense activity in this area, effective methods of coarse-graining have been slow to develop. Our approach to this fundamental problem starts from the observation that integrating out degrees of freedom of the AA model leads to a strong modification of the configurational entropy and cohesive interaction. Based on this observation, we propose a temperature-dependent systematic renormalization of the cohesive interaction in the CG modeling to recover the thermodynamic modifications in the system and the dynamics of the AA model. Here, we show that this energy renormalization approach to CG can faithfully estimate the diffusive, segmental and glassy dynamics of the AA model over a large temperature range spanning from the Arrhenius melt to the non-equilibrium glassy states. Our proposed CG strategy offers a promising strategy for developing thermodynamically consistent CG models with temperature transferability.
NASA Astrophysics Data System (ADS)
Toni Liong, Rugerri; Proppe, Carsten
2013-04-01
The breathing mechanism of a transversely cracked rotor and its influence on a rotor system that appears due to shaft weight and inertia forces is studied. A method is proposed for the evaluation of the stiffness losses in the cross-section that contains the crack. This method is based on a cohesive zone model (CZM) instead of linear elastic fracture mechanics (LEFM). The CZM is developed for mode-I plane strain conditions and accounts explicitly for triaxiality of the stress state by using constitutive relations. The breathing crack is modelled by a parabolic shape. As long as the relative crack depth is small, a crack closure straight line model may be used, while the crack closure parabolic line should be used in the case of a deep crack. The CZM is also implemented in a one-dimensional continuum rotor model by means of finite element (FE) discretisation in order to predict and to analyse the dynamic behavior of a cracked rotor. The proposed method provides a useful tool for the analysis of rotor systems containing cracks.
Partial synchronization in networks of non-linearly coupled oscillators: The Deserter Hubs Model
DOE Office of Scientific and Technical Information (OSTI.GOV)
Freitas, Celso, E-mail: cbnfreitas@gmail.com; Macau, Elbert, E-mail: elbert.macau@inpe.br; Pikovsky, Arkady, E-mail: pikovsky@uni-potsdam.de
2015-04-15
We study the Deserter Hubs Model: a Kuramoto-like model of coupled identical phase oscillators on a network, where attractive and repulsive couplings are balanced dynamically due to nonlinearity of interactions. Under weak force, an oscillator tends to follow the phase of its neighbors, but if an oscillator is compelled to follow its peers by a sufficient large number of cohesive neighbors, then it actually starts to act in the opposite manner, i.e., in anti-phase with the majority. Analytic results yield that if the repulsion parameter is small enough in comparison with the degree of the maximum hub, then the fullmore » synchronization state is locally stable. Numerical experiments are performed to explore the model beyond this threshold, where the overall cohesion is lost. We report in detail partially synchronous dynamical regimes, like stationary phase-locking, multistability, periodic and chaotic states. Via statistical analysis of different network organizations like tree, scale-free, and random ones, we found a measure allowing one to predict relative abundance of partially synchronous stationary states in comparison to time-dependent ones.« less
Characteristics of Non-Cohesive Embankment Failure
NASA Astrophysics Data System (ADS)
Yusof, Z. M.; Wahab, A. K. A.; Ismail, Z.; Amerudin, S.
2018-04-01
Embankments are important infrastructure built to provide flood control. They also present risks to property and life due to their potential to fail and cause catastrophic flooding. To mitigate these risks, authorities and regulators need to carefully analyse and inspect dams to identify potential failure modes and protect against them. This paper presents morphology of an embankment study and its sediment behaviour of different grain sizes after the embankment fails. A few experiments were carried out for the embankment size of 1V:3H with different sediment grain sizes; medium and coarser sand. The embankment material used is non-cohesive soil with the embankment height of 0.1 m. The embankment is tested with inflows rate of Q = 0.8 L/s. Experimental results showed the peak discharge for the same inflow rate is affected by the shape of embankment breached. The peak discharge of medium grain size of the embankment is highest, which gave 3.63 L/s in comparison with a coarser embankment. This concludes that the embankment morphology patterns are dissimilar to each other. The flow and dimension of embankment are shown to influence the characteristics of embankment failure.
NASA Astrophysics Data System (ADS)
Ukpong, A. M.; Chetty, N.
2012-05-01
The van der Waals interaction-corrected density functional theory is used in this study to investigate the formation, energetic stability, and inter-layer cohesion in bilayer hexagonal boronitrene. The effect of inter-layer separation on the electronic structure is systematically investigated. The formation and energetic stability of intrinsic defects are also investigated at the equilibrium inter-layer separation. It is found that nonstoichiometric defects, and their complexes, that induce excess nitrogen or excess boron, in each case, are relatively more stable in the atmosphere that corresponds to the excess atomic species. The modifications of the electronic structure due to formation of complexes are also investigated. It is shown that van der Waals density functional theory gives an improved description of the cohesive properties but not the electronic structure in bilayer boronitrene compared to other functionals. We identify energetically favourable topological defects that retain the energy gap in the electronic structure, and discuss their implications for band gap engineering in low-n layer boronitrene insulators. The relative strengths and weaknesses of the functionals in predicting the properties of bilayer boronitrene are also discussed.
1998-06-01
the Nation’s Course : Strategic Planning Processes in the 1952-53 " New Look" and the 1996-97 Quadrennial...sequences into a cohesive whole. Two examples ( the New Look of 1953 and the Quadrennial Defense Review of 1997) are selected for comparison due to the many...By 1953, atomic weapons were becoming more numerous and hydrogen weapons were about to be tested for the first time. 17 Bombers, cruise missiles,
REFRACTORY ARTICLE AND PROCESS OF MANUFACTURING SAME
Hamilton, N.E.
1957-12-10
A method is described for fabricating improved uranium oxide crucibles. In the past, such crucibles have lacked mechanical strength due to the poor cohesion of the uranium oxide particles. This difficulty has now been overcome by admixing with the uranium oxide a quantity of a refractory oxide binder, and dry pressing and sintering the resulting mixture into the desired shape. Suitable as binders are BeO, CaO, Al/sub 2/C/sub 3/, and ThO/sub 2/ among others.
Dong, XinQi; Bergren, Stephanie M
2017-08-01
Characteristics of neighborhood have been found to be associated with physical and psychological health status of older adults, especially in relationship to social dynamics like cohesion and disorder. This study aims to examine correlations and associations between sociodemographic characteristics, self-reported health status, cohesion, and disorder among Chinese older adults in the greater Chicago area. The Population Study of Chinese Elderly in Chicago is a cross-sectional, population-based study with community-dwelling Chinese older adults aged 60 and older, recruited through a community-based participatory research approach. Cohesion was measured through six questions; disorder was measured through eight questions. Correlation and regression analyses were conducted using SAS. Among 3,158 participants enrolled in the study, 92.3% reported any neighborhood cohesion; 69.8% reported any neighborhood disorder. After controlling for age, sex, education, income, marital status, living arrangement, number of children, years in the community, years in the United States, country of origin, language preference, and location, a higher level of cohesion is associated with higher quality of life (odds ratio [OR]: 1.25, 95% confidence interval [CI]: 1.13, 1.39) and a higher level of disorder is associated with lower overall health status (OR: 0.97, 95% CI: 0.95, 0.99) and lower quality of life (OR: 0.96, 95% CI: 0.95, 0.98). Our findings suggest that neighborhood cohesion and neighborhood disorder are correlated to the health of U.S. Chinese older adults. Future longitudinal research should examine the relationship between community characteristics, both structural and social, and health-related outcomes. © The Author 2016. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.
Fone, D; White, J; Farewell, D; Kelly, M; John, G; Lloyd, K; Williams, G; Dunstan, F
2014-08-01
The common mental disorders (CMDs) of anxiety and depression are the most common form of poor mental health in the general population. Evidence from the small number of previous cohort studies on the role of neighbourhood factors in mental health is inconclusive. We tested the hypothesis that high levels of neighbourhood social cohesion modify an adverse association between change in individual mental health and neighbourhood deprivation. We carried out a longitudinal multilevel analysis using data from the Caerphilly Health and Social Needs Cohort Study with a 7-year follow-up (n = 4426; age range 18-74 years at baseline). Neighbourhood deprivation and neighbourhood social cohesion were assessed at baseline and change in mental health between follow-up and baseline was assessed using the five-item Mental Health Inventory (MHI-5). Residence in the most deprived neighbourhoods was negatively associated with change in mental health, after adjusting for baseline individual socio-economic risk factors and transitions in life events. This negative effect was significantly reduced in high social cohesion neighbourhoods. The predicted change in mental health score was calculated for the 10th and 90th centiles of the household low-income distribution. The difference between them was -2.8 in the low social cohesion group and 1.1 in the high cohesion group. The difference between the groups was 3.9 [95% confidence interval (CI) 0.2-7.6]. The public health burden of poor mental health and mental health inequality could potentially be reduced by strengthening social cohesion in deprived neighbourhoods. This offers a mechanism to address the adverse effect of neighbourhood deprivation on population mental health.
Shen, Chen; Wan, Alice; Kwok, Lit Tung; Pang, Sally; Wang, Xin; Stewart, Sunita M; Lam, Tai Hing; Chan, Sophia S
2017-01-01
Neighborhood cohesion, which refers to the extent of the connectedness and solidarity among residents in a community or neighborhood, is an important determinant of human health. To enhance neighborhood cohesion, the "Learning Families Project" was developed with a series of intervention programs in Kwun Tong in Hong Kong, a district with low neighborhood cohesion. This project, based on the social ecological model, provided a platform for neighbors to learn, communicate and interact with each other. This quasi-experimental study included two nearby government subsidized low rent housing estates separated by busy main roads. One served as the intervention (Tsui Ping (South) Estate) and one as the control (Shun Tin Estate) estate. The intervention included promotion, resident training and learning programs, embodied by a series of community activities such as talks, day camp, thematic activities and horticulture class. Baseline (before the programs) and follow-up (one year after the programs) surveys were conducted both in the intervention and control estate to assess the impact of the programs on neighborhood cohesion. The number of residents who completed both the baseline and follow-up surveys was 502 in the intervention estate and 476 in the control estate. Neighborhood cohesion significantly improved in the intervention group after the programs (Cohen effect size d: 0.15). Compared with the control group, the improvements in closeness of the neighborhood and trust in neighbors were significantly greater in the intervention group (Cohen effect size d: 0.13 and 0.14, respectively). This brief intervention program using a quasi-experimental study design increased neighborhood cohesion in a low rent housing estate. ClinicalTrials.gov NCT02851667.
Wan, Alice; Kwok, Lit Tung; Pang, Sally; Wang, Xin; Stewart, Sunita M.; Lam, Tai Hing; Chan, Sophia S.
2017-01-01
Background Neighborhood cohesion, which refers to the extent of the connectedness and solidarity among residents in a community or neighborhood, is an important determinant of human health. To enhance neighborhood cohesion, the “Learning Families Project” was developed with a series of intervention programs in Kwun Tong in Hong Kong, a district with low neighborhood cohesion. This project, based on the social ecological model, provided a platform for neighbors to learn, communicate and interact with each other. Methods This quasi-experimental study included two nearby government subsidized low rent housing estates separated by busy main roads. One served as the intervention (Tsui Ping (South) Estate) and one as the control (Shun Tin Estate) estate. The intervention included promotion, resident training and learning programs, embodied by a series of community activities such as talks, day camp, thematic activities and horticulture class. Baseline (before the programs) and follow-up (one year after the programs) surveys were conducted both in the intervention and control estate to assess the impact of the programs on neighborhood cohesion. Results The number of residents who completed both the baseline and follow-up surveys was 502 in the intervention estate and 476 in the control estate. Neighborhood cohesion significantly improved in the intervention group after the programs (Cohen effect size d: 0.15). Compared with the control group, the improvements in closeness of the neighborhood and trust in neighbors were significantly greater in the intervention group (Cohen effect size d: 0.13 and 0.14, respectively). Conclusion This brief intervention program using a quasi-experimental study design increased neighborhood cohesion in a low rent housing estate. Trial registration ClinicalTrials.gov NCT02851667 PMID:28827798
Model of cohesive properties and structural phase transitions in non-metallic solids
DOE Office of Scientific and Technical Information (OSTI.GOV)
Majewski, J.A.; Vogl, P.
1986-01-01
We have developed a simple, yet microscopic and universal model for cohesive properties of solids. This model explains the physical mechanisms determining the chemical and predicts semiquantitatively static and dynamic cohesive properties. It predicts a substantial softening of the long-wavelength transverse optical phonons across the pressure induced phase transition from the zincblenda to rocksalt structure in II-VI compounds. The origin of this softening is shown to be closely related to ferroelectricity.
Leadership, cohesion, morale, and the mental health of UK Armed Forces in Afghanistan.
Jones, Norman; Seddon, Rachel; Fear, Nicola T; McAllister, Pete; Wessely, Simon; Greenberg, Neil
2012-01-01
UK Armed Forces (AF) personnel deployed to Afghanistan are frequently exposed to intense combat and yet little is known about the short-term mental health consequences of this exposure and the potential mitigating effects of military factors such as cohesion, morale, and leadership. To assess the possible modulating influence of cohesion, morale, and leadership on post-traumatic stress disorder (PTSD) symptoms and common mental disorders resulting from combat exposure among UK AF personnel deployed to Afghanistan, UK AF personnel, during their deployment to Afghanistan in 2010, completed a self-report survey about aspects of their current deployment, including perceived levels of cohesion, morale, leadership, combat exposure, and their mental health status. Outcomes were symptoms of common mental disorder and symptoms of PTSD. Combat exposure was associated with both PTSD symptoms and symptoms of common mental disorder. Of the 1,431 participants, 17.1% reported caseness levels of common mental disorder, and 2.7% were classified as probable PTSD cases. Greater self-reported levels of unit cohesion, morale, and perceived good leadership were all associated with lower levels of common mental disorder and PTSD. Greater levels of unit cohesion, morale, and good leadership may help to modulate the effects of combat exposure and the subsequent development of mental health problems among UK Armed Forces personnel deployed to Afghanistan. © 2012 Guilford Publications, Inc.
Cohesive Laws for Analyzing Through-Crack Propagation in Cross Ply Laminates
NASA Technical Reports Server (NTRS)
Bergan, Andrew C.; Davila, Carlos G.
2015-01-01
The laminate cohesive approach (LCA) is a methodology for the experimental characterization of cohesive through-the-thickness damage propagation in fiber-reinforced polymer matrix composites. LCA has several advantages over other existing approaches for cohesive law characterization, including: visual measurements of crack length are not required, structural effects are accounted for, and LCA can be applied when the specimen is too small to achieve steady-state fracture. In this work, the applicability of this method is investigated for two material systems: IM7/8552, a conventional prepreg, and AS4/VRM34, a non-crimp fabric cured using an out-of-autoclave process. The compact tension specimen configuration is used to propagate stable Mode I damage. Trilinear cohesive laws are characterized using the fracture toughness and the notch tip opening displacement. Test results are compared for the IM7/8552 specimens with notches machined by waterjet and by wire slurry saw. It is shown that the test results are nearly identical for both notch tip preparations methods, indicating that significant specimen preparation time and cost savings can be realized by using the waterjet to notch the specimen instead of the wire slurry saw. The accuracy of the cohesive laws characterized herein are assessed by reproducing the structural response of the test specimens using computational methods. The applicability of the characterization procedure for inferring lamina fracture toughness is also discussed.
Displacement, county social cohesion and depression after a large-scale traumatic event
Lê, Félice; Tracy, Melissa; Norris, Fran H.; Galea, Sandro
2013-01-01
Background Depression is a common and potentially debilitating consequence of traumatic events. Mass traumatic events cause wide-ranging disruptions to community characteristics, influencing the population risk of depression. In the aftermath of such events, population displacement is common. Stressors associated with displacement may increase risk of depression directly. Indirectly, persons who are displaced may experience erosion in social cohesion, further exacerbating their risk for depression. Methods Using data from a population-based cross-sectional survey of adults living in the 23 southernmost counties of Mississippi (N = 708), we modeled the independent and joint relations of displacement and county-level social cohesion with depression 18–24 months after Hurricane Katrina. Results After adjustment for individual- and county-level sociodemographic characteristics and county-level hurricane exposure, joint exposure to both displacement and low social cohesion was associated with substantially higher log-odds of depression (b = 1.34 [0.86–1.83]). Associations were much weaker for exposure only to low social cohesion (b = 0.28 [−0.35–0.90]) or only to displacement (b = 0.04 [−0.80– 0.88]). The associations were robust to additional adjustment for individually perceived social cohesion and social support. Conclusion Addressing the multiple, simultaneous disruptions that are a hallmark of mass traumatic events is important to identify vulnerable populations and understand the psychological ramifications of these events. PMID:23644724
Social cohesion and mortality: a survival analysis of older adults in Japan.
Inoue, Sachiko; Yorifuji, Takashi; Takao, Soshi; Doi, Hiroyuki; Kawachi, Ichiro
2013-12-01
We examined the association between social cohesion and mortality in a sample of older adults in Japan. Data were derived from a cohort study of elderly individuals (65-84 years) in Shizuoka Prefecture; 14 001 participants were enrolled at baseline (1999) and followed up in 2002, 2006, and 2009. Among the 11 092 participants for whom we had complete data, 1427 had died during follow-up. We examined the association between social cohesion (assessed at both the community and individual levels) and subsequent mortality after control for baseline and time-varying covariates. We used clustered proportional hazard regression models to estimate hazard ratios (HRs) and confidence intervals (CIs). After control for individual characteristics, individual perceptions of community cohesion were associated with a reduced risk of all-cause mortality (HR = 0.78; 95% CI = 0.73, 0.84) as well as mortality from cardiovascular disease (HR = 0.75; 95% CI = 0.67, 0.84), pulmonary disease (HR = 0.66; 95% CI = 0.58, 0.75), and all other causes (HR = 0.76; 95% CI = 0.66, 0.89). However, no statistically significant relationship was found between community cohesion and mortality risk. Among the elderly in Japan, more positive individual perceptions of community cohesion are associated with reduced risks of all-cause and cause-specific mortality.
Social Cohesion and Mortality: A Survival Analysis of Older Adults in Japan
Yorifuji, Takashi; Takao, Soshi; Doi, Hiroyuki; Kawachi, Ichiro
2013-01-01
Objectives. We examined the association between social cohesion and mortality in a sample of older adults in Japan. Methods. Data were derived from a cohort study of elderly individuals (65–84 years) in Shizuoka Prefecture; 14 001 participants were enrolled at baseline (1999) and followed up in 2002, 2006, and 2009. Among the 11 092 participants for whom we had complete data, 1427 had died during follow-up. We examined the association between social cohesion (assessed at both the community and individual levels) and subsequent mortality after control for baseline and time-varying covariates. We used clustered proportional hazard regression models to estimate hazard ratios (HRs) and confidence intervals (CIs). Results. After control for individual characteristics, individual perceptions of community cohesion were associated with a reduced risk of all-cause mortality (HR = 0.78; 95% CI = 0.73, 0.84) as well as mortality from cardiovascular disease (HR = 0.75; 95% CI = 0.67, 0.84), pulmonary disease (HR = 0.66; 95% CI = 0.58, 0.75), and all other causes (HR = 0.76; 95% CI = 0.66, 0.89). However, no statistically significant relationship was found between community cohesion and mortality risk. Conclusions. Among the elderly in Japan, more positive individual perceptions of community cohesion are associated with reduced risks of all-cause and cause-specific mortality. PMID:24134379
Regolith on Super Fast Rotators
NASA Astrophysics Data System (ADS)
Sanchez Lana, Diego Paul; Scheeres, Daniel J.
2017-10-01
The current understanding of small asteroids in the Solar System is that they are gravitational aggregates held together by gravitational, cohesive and adhesive forces. Results from the Hayabusa mission to Itokawa along with in situ, thermal and radar observations of asteroids have shown that they can be covered in a size distribution of grains that spans from microns to tens of meters. Before the Hayabusa mission, it was generally thought that smaller asteroids would likely be “regolith-free,” due to impact seismic shaking removing the loose covering. Given the regolith-rich surface of that body, it is now an open question whether even smaller bodies, down to a few meters in size, could also retain regolith covering. The question is especially compelling for the small-fast rotators, whose surface centripetal accelerations exceed their gravitational attraction. When the physical theory of cohesion is considered, it becomes possible for small-fast rotators to retain regolith.We use a Soft-Sphere discrete element method (SSDEM) code to simulate a longitudinal slice of a spherical monolith covered by cohesive regolith. The simulations are carried out in the body frame. Tensile strength is varied to span the observed strength of asteroids and spin rate is elevated in small steps until the majority of regolith is removed from the surface. The simulations show that under an increasing spin rate (such as due to the YORP effect), the regolith covering on an otherwise monolithic asteroid is preferentially lost across certain regions of the body. In general, regolith from the mid latitudes is the first to fail at high spin rates. This failure happens either by regolith flowing towards the equator or by detachment of large coherent chunks of material depending on the tensile strength of the regolith. Regolith from the equator region fails next, usually by the detachment of large pieces. Regolith from the poles stays in place unless the spin rates are extremely high. With these results we derive a scaling law that can be used to determine whether observed small asteroids could retain surface regolith of a given size. The implications of this for the interpretation of spectral observations of small asteroids are discussed.
Dry powder segregation and flowability: Experimental and numerical studies
NASA Astrophysics Data System (ADS)
Ely, David R.
Dry powder blending is a very important industrial and physical process used in the production of numerous pharmaceutical dosage forms such as tablets, capsules, and dry powder aerosols. Key aspects of this unit operation are process monitoring and control. Process control is particularly difficult due to the complexity of particle-particle interactions, which arise from the adhesion/cohesion characteristics of interfaces and morphological characteristics such as particle size, shape, and dispersity. The effects of such characteristics need to be understood in detail in order to correlate individual particle properties to bulk powder properties. The present dissertation numerically and experimentally quantifies the mixing process to rationalize particle-particle interactions. In particular, near infrared spectroscopy (NIRS) was used to non-invasively characterize in real-time the blending processes and thus investigate the dynamics of blending under different operating conditions. A novel image analysis technique was developed to quantify the scale of segregation from images obtained non-destructively via near infrared chemical imaging (NIR-CI). Although NIR-CI data acquisition times are too long for real-time data collection, NIR-CI has an advantage, in that it provides the spatial distribution of the drug. Therefore, NIRS and NIR-CI are complementary techniques for investigating the complex process of blending dry powders and assessing end-product quality. Additionally, the discrete element method was used to investigate the effect of powder cohesion on the packing fraction. Simulations indicated an exponential relationship between the random loose packing fraction and cohesive forces. Specifically, the packing fraction decreased asymptotically with increased ratio of cohesive force to particle weight. Thus, increasing this force ratio above a critical value has negligible impact on the packing fraction. Such result directly impacts the Hausner ratio flowability measurement, which is directly related to the packing fraction. Two commonly used tests were compared to assess their utility: the rotational split-cell shear cell test and the Hausner ratio. The Hausner ratio proved to be better suited for characterizing the flowability of unconsolidated powders than the splitring shear cell. Results demonstrate that the optimal flowability test depends on the powder properties and the environment under which flow will be induced.
Influence of Natural Fractures Cohesive Properties on Geometry of Hydraulic Fracture Networks
NASA Astrophysics Data System (ADS)
Gonzalez-Chavez, M. A.; Dahi Taleghani, A.; Puyang, P.
2014-12-01
An integrated modeling methodology is proposed to analyze hydraulic fracturing jobs in the presence of the natural fracture network in the formation. A propagating hydraulic fracture may arrest, cross, or diverts into a preexisting natural crack depending on fracture properties of rock and magnitude and direction of principal rock stresses. Opening of natural fractures during fracturing treatment could define the effectiveness of the stimulation technique. Here, we present an integrated methodology initiated with lab scale fracturing properties using Double Cantilever Beam tests (DCB) to determine cohesive properties of rock and natural fractures. We used cohesive finite element models to reproduce laboratory results to verify the numerical model for the interaction of the hydraulic fracture and individual cemented natural fractures. Based on the initial investigations, we found out that distribution of pre-existing natural fractures could play a significant role in the final geometry of the induced fracture network; however in practice, there is not much information about the distribution of natural fractures in the subsurface due to the limited access. Hence, we propose a special optimization scheme to generate natural fracture geometry from the location of microseismic events. Accordingly, the criteria of evaluating the fitness of natural fracture realizations is defined as the total minimum distance squares of all microseismic events, which is the sum of minimum square distance for all microseismic events. Moreover, an additional constraint in this problem is that we need to set a minimum distance between fracture grids. Using generated natural fracture realizations, forward field-scale simulations are implemented using cohesive finite element analysis to find the best match with the recorded bottomhole pressure. To show the robustness of the proposed workflow for real field problem, we implemented this technique on available data from several well Chicontepec basin to forecast post-treatment production rate. Our results show a constructive approach to integrate microseismic maps with lab mechanical measurements and bottomhole pressure to estimate the geometry of induced fracture network in the subsurface which does not suffer from any limiting assumption about fracture geometries.
Global expression for representing cohesive-energy curves. II
NASA Technical Reports Server (NTRS)
Schlosser, Herbert; Ferrante, John
1993-01-01
Schlosser et al. (1991) showed that the R dependence of the cohesive energy of partially ionic solids may be characterized by a two-term energy relationship consisting of a Coulomb term arising from the charge transfer, delta-Z, and a scaled universal energy function, E*(a *), which accounts for the partially covalent character of the bond and for repulsion between the atomic cores for small R; a* is a scaled length. In the paper by Schlosser et al., the normalized cohesive-energy curves of NaCl-structure alkali-halide crystals were generated with this expression. In this paper we generate the cohesive-energy curves of several families of partially ionic solids with different crystal structures and differing degrees of ionicity. These include the CsCl-structure Cs halides, and the Tl and Ag halides, which have weaker ionic bonding than the alkali halides, and which have the CsCl and NaCl structures, respectively. The cohesive-energy-curve parameters are then used to generate theoretical isothermal compression curves for the Li, Na, K, Cs, and Ag halides. We find good agreement with the available experimental compression data.
Hong, Seunghye; Zhang, Wei; Walton, Emily
2014-01-01
This study examines the associations of neighborhood ethnic density and poverty with social cohesion and self-rated mental health among Asian Americans and Latinos. Path analysis is employed to analyze data from the 2002–2003 National Latino and Asian American Study (NLAAS) and the 2000 U.S. Census (N=2095 Asian Americans living in N=259 neighborhoods; N=2554 Latinos living in N=317 neighborhoods). Findings reveal that neighborhood ethnic density relates to poor mental health in both groups. Social cohesion partially mediates that structural relationship, but is positively related to ethnic density among Latinos and negatively related to ethnic density among Asian Americans. Although higher neighborhood poverty is negatively associated with mental health for both groups, the relationship does not hold in the path models after accounting for social cohesion and covariates. Furthermore, social cohesion fully mediates the association between neighborhood poverty and mental health among Latinos. This study highlights the necessity of reconceptualizing existing theories of social relationships to reflect complex and nuanced mechanisms linking neighborhood structure and mental health for diverse racial and ethnic groups. PMID:24769491
The transitional behaviour of avalanches in cohesive granular materials
NASA Astrophysics Data System (ADS)
Quintanilla, M. A. S.; Valverde, J. M.; Castellanos, A.
2006-07-01
We present a statistical analysis of avalanches of granular materials that partially fill a slowly rotated horizontal drum. For large sized noncohesive grains the classical coherent oscillation is reproduced, consisting of a quasi-periodic succession of regularly sized avalanches. As the powder cohesiveness is increased by decreasing the particle size, we observe a gradual crossover to a complex dynamics that resembles the transitional behaviour observed in fusion plasmas. For particle size below ~50 µm, avalanches lose a characteristic size, retain a short term memory and turn gradually decorrelated in the long term as described by a Markov process. In contrast, large grains made cohesive by coating them with adhesive microparticles display a distinct phenomenology, characterized by a quasi-regular succession of well defined small precursors and large relaxation events. The transition from a one-peaked distribution (noncohesive large beads) to a flattened distribution (fine cohesive beads) passing through the two-peaked distribution of cohesive large beads had already been predicted using a coupled-map lattice model, as the relaxation mechanism of grain reorganization becomes dominant to the detriment of inertia.
Grain-resolving simulations of settling cohesive sediment
NASA Astrophysics Data System (ADS)
Vowinckel, Bernhard; Whithers, Jade; Meiburg, Eckart; Luzzatto-Fegiz, Paolo
2017-11-01
Cohesive sediment is ubiquitous in natural environments such as rivers, lakes and coastal ecosystems. For this type of sediment, we can no longer ignore the short-range attractive forces that result in flocculation of aggregates much larger than the individual grain size. Hence, understanding the complex dynamics of the interplay between flocculated sediment and the ambient fluid is of prime interest for managing aquatic environments, although a comprehensive understanding of these phenomena is still lacking. In the present study, we address this issue by carrying out grain-resolved simulations of cohesive particles settling under gravity using the Immersed Boundary Method. We present a computational model formulation to accurately resolve the process of flocculation. The cohesive model is then applied to a complex test case. A randomly distributed ensemble of 1261 polydisperse particles is released in a tank of quiescent fluid. Subsequently, particles start to settle, thereby replacing fluid at the bottom of the tank, which induces a counter flow opposing the settling direction. This mechanism will be compared to experimental studies from the literature, as well as to the non-cohesive counterpart to assessthe impact of flocculation on sedimentation.
Group cohesion and nurse satisfaction: examination of a team-building approach.
DiMeglio, Karen; Padula, Cynthia; Piatek, Carolyn; Korber, Susan; Barrett, Ann; Ducharme, Maria; Lucas, Sandra; Piermont, Nicole; Joyal, Elaine; DeNicola, Virginia; Corry, Karen
2005-03-01
The purpose of this study was to determine the impact of a team-building intervention on group cohesion, nurse satisfaction, and turnover rates. Creating an environment that supports and retains nurses represents a formidable challenge for nursing leaders. Research related to strategies that positively impact the culture in which nurses practice, thus potentially improving nurse satisfaction and reducing turnover, is critically needed. Registered nurses (RNs) employed on inpatient units in a 247-bed, private acute care Magnet teaching hospital participated in this quasi experimental preintervention and postintervention design. The RN-RN interaction subscale from the National Database of Nursing Quality Indicators Adapted Index of Work Satisfaction, the National Database of Nursing Quality Indicators Adapted Index of Job Enjoyment, the Group Cohesion Scale, and a facilitator-developed measure were completed preimplementation and postimplementation of unit-tailored intervention strategies, which took place over a 12-month period. Turnover rates were collected 6 month preintervention and postintervention. Improvement in group cohesion, RN-RN interaction, job enjoyment, and turnover was demonstrated. Targeted, unit-based strategies can be an effective means of reducing turnover rates and improving group cohesion and nurse satisfaction.
Yan, Rihui; Thomas, Sharon E; Tsai, Jui-He; Yamada, Yukihiro; McKee, Bruce D
2010-02-08
Sister chromatid cohesion is essential to maintain stable connections between homologues and sister chromatids during meiosis and to establish correct centromere orientation patterns on the meiosis I and II spindles. However, the meiotic cohesion apparatus in Drosophila melanogaster remains largely uncharacterized. We describe a novel protein, sisters on the loose (SOLO), which is essential for meiotic cohesion in Drosophila. In solo mutants, sister centromeres separate before prometaphase I, disrupting meiosis I centromere orientation and causing nondisjunction of both homologous and sister chromatids. Centromeric foci of the cohesin protein SMC1 are absent in solo mutants at all meiotic stages. SOLO and SMC1 colocalize to meiotic centromeres from early prophase I until anaphase II in wild-type males, but both proteins disappear prematurely at anaphase I in mutants for mei-S332, which encodes the Drosophila homologue of the cohesin protector protein shugoshin. The solo mutant phenotypes and the localization patterns of SOLO and SMC1 indicate that they function together to maintain sister chromatid cohesion in Drosophila meiosis.
Psychosocial issues affecting crews during long-duration international space missions.
Kanas, N
1998-01-01
Psychosocial issues can negatively impact on crew performance and morale during long-duration international space missions. Major psychosocial factors that have been described in anecdotal reports from space and in studies from analog situations on Earth include: 1) crew heterogeneity due to gender differences, cultural issues, and work experiences and motivations; 2) language and dialect variations; and 3) task versus supportive leadership roles. All of these factors can lead to negative sequelae, such as intra-crew tension and cohesion disruptions. Specific sequelae that can result from single factors include subgrouping and scapegoating due to crew heterogeneity; miscommunication due to major or subtle language differences; and role confusion, competition, and status leveling due to inappropriate leadership role definition. It is time to conduct research exploring the impact of these psychosocial factors and their sequelae on space crews during actual long-duration international space missions.
Psychosocial issues affecting crews during long-duration international space missions
NASA Technical Reports Server (NTRS)
Kanas, N.
1998-01-01
Psychosocial issues can negatively impact on crew performance and morale during long-duration international space missions. Major psychosocial factors that have been described in anecdotal reports from space and in studies from analog situations on Earth include: 1) crew heterogeneity due to gender differences, cultural issues, and work experiences and motivations; 2) language and dialect variations; and 3) task versus supportive leadership roles. All of these factors can lead to negative sequelae, such as intra-crew tension and cohesion disruptions. Specific sequelae that can result from single factors include subgrouping and scapegoating due to crew heterogeneity; miscommunication due to major or subtle language differences; and role confusion, competition, and status leveling due to inappropriate leadership role definition. It is time to conduct research exploring the impact of these psychosocial factors and their sequelae on space crews during actual long-duration international space missions.
Friends of friends: are indirect connections in social networks important to animal behaviour?
Brent, Lauren J N
2015-05-01
Friend of a friend relationships, or the indirect connections between people, influence our health, well-being, financial success and reproductive output. As with humans, social behaviours in other animals often occur within a broad interconnected network of social ties. Yet studies of animal social behaviour tend to focus on associations between pairs of individuals. With the increase in popularity of social network analysis, researchers have started to look beyond the dyad to examine the role of indirect connections in animal societies. Here, I provide an overview of the new knowledge that has been uncovered by these studies. I focus on research that has addressed both the causes of social behaviours, i.e. the cognitive and genetic basis of indirect connections, as well as their consequences, i.e. the impact of indirect connections on social cohesion, information transfer, cultural practices and fitness. From these studies, it is apparent that indirect connections play an important role in animal behaviour, although future research is needed to clarify their contribution.
Turning the tide: estuarine bars and mutually evasive ebb- and flood-dominated channels
NASA Astrophysics Data System (ADS)
Kleinhans, M. G.; Leuven, J.; van der Vegt, M.; Baar, A. W.; Braat, L.; Bergsma, L.; Weisscher, S.
2015-12-01
Estuaries have perpetually changing and interacting channels and shoals formed by ebb and flood currents, but we lack a descriptive taxonomy and forecasting model. We explore the hypotheses that the great variation of bar and shoal morphologies are explained by similar factors as river bars, namely channel aspect ratio, sediment mobility and limits on bar erosion and chute cutoff caused by cohesive sediment. Here we use remote sensing data and a novel tidal flume setup, the Metronome, to create estuaries or short estuarine reaches from idealized initial conditions, with and without mud supply at the fluvial boundary. Bar width-depth ratios in estuaries are similar to those in braided rivers. In unconfined (cohesionless) experimental estuaries, bar- and channel dynamics increase with increasing river discharge. Ebb- and flood-dominated channels are ubiquitous even in entirely straight sections. The apparent stability of ebb- and flood channels is partly explained by the inherent instability of symmetrical channel bifurcations as in rivers.
Friends of friends: are indirect connections in social networks important to animal behaviour?
Brent, Lauren J. N.
2015-01-01
Friend of a friend relationships, or the indirect connections between people, influence our health, well-being, financial success and reproductive output. As with humans, social behaviours in other animals often occur within a broad interconnected network of social ties. Yet studies of animal social behaviour tend to focus on associations between pairs of individuals. With the increase in popularity of social network analysis, researchers have started to look beyond the dyad to examine the role of indirect connections in animal societies. Here, I provide an overview of the new knowledge that has been uncovered by these studies. I focus on research that has addressed both the causes of social behaviours, i.e. the cognitive and genetic basis of indirect connections, as well as their consequences, i.e. the impact of indirect connections on social cohesion, information transfer, cultural practices and fitness. From these studies, it is apparent that indirect connections play an important role in animal behaviour, although future research is needed to clarify their contribution. PMID:25937639
Building social capital in healthcare organizations: thinking ecologically for safer care.
Hofmeyer, Anne; Marck, Patricia B
2008-01-01
Research on patient safety and health human resources, 2 critical issues for 21st century healthcare, converges on similar findings. Specifically, it is apparent that along with the patients, families, and communities we serve, nurses and other healthcare professionals navigate a volatile health care system where persistent restructuring, market pressures, and workforce instability present ongoing threats to the delivery of safer care. Drawing from the fields of nursing, healthcare ethics, health systems management, and ecological restoration, we outline the role of social capital for organizational integrity, healthy workplace cultures, sustainable resource management, improved nurse retention, effective knowledge translation, and safer patient care. Nursing leaders can use ecological thinking to build the vital resource of social capital by taking concrete steps to commit the necessary human and material resources to: (1) forge relations to foster bonding, bridging and linking social capital; (2) build solidarity and trust; (3) foster collective action and cooperation; (4) strengthen communication and knowledge exchange; and (5) create capacity for social cohesion and inclusion.
DOE Office of Scientific and Technical Information (OSTI.GOV)
Setyawan, Wahyu; Kurtz, Richard J.
2014-03-13
Density functional theory calculations were performed to study the effects of H, He, Li and Be on the cohesion of W Σ3<110>{112} and Σ27<110>{552} grain boundaries (GBs). In Σ3, Li causes the strongest embrittlement, while in Σ27 it is He. In both GBs, H slightly reduces the cohesion. Compared to He and Li, H exhibits much stronger attractive binding with W that may inhibit subsequent segregation of Li and He to the GBs. In Σ3, Be decreases the cohesion. However, in Σ27, Be strengthens the cohesion in several interstitial positions by increasing the bonding across the interface or by inducingmore » GB restructuring.« less
NASA Astrophysics Data System (ADS)
Harb, Gabriele; Haun, Stefan
2013-04-01
Reservoir sedimentation is a common problem today. Due to the reduced flow velocities, turbulences and bed shear stresses the transported sediment load start to settle. These depositions reduce the worldwide average storage capacity in the range of about 1% per year. However, depending on the climate conditions and the geology in the catchment area this value may vary strongly. Therefore sediment management tasks, especially the removal of already accumulated sediments, have to be developed for each reservoir separately. The critical bed shear stress is a key parameter used to evaluate the different management tasks and depend strongly on the grain size distribution of the inflowing sediments. However, depositions which contain fine particles like clay and silt increase the critical bed shear stress due to occurring cohesive forces and the use of the Shield curve for evaluating the critical shear stress is no longer valid. Additional data is required for estimating the valid critical shear stress at the reservoir bed. In this study the critical shear stress was evaluated for cohesive sediment samples, taken from two different reservoirs, in a flume in the laboratory. The sediment samples were placed in an installed double bottom in the research flume and the discharge was increased stepwise until mass erosion took place (determined by visual inspection). A 2D PIV device was used to measure the flow conditions (velocities and turbulences) over the sediment sample. The obtained values were used to calculate the bed shear stress for the specific discharge rate by the gravity method and the Reynolds stress method. The results of both methods showed good agreement in the comparison of the values, what indicates that nearly uniform flow conditions occurred in the flume. The results from this study showed that the behaviour of natural cohesive sediments depend strongly on the natural conditions as a result of physical, chemical and biological processes. In this case especially the effect of the layer structure in the sediment samples was controlling the erosion mechanism. The results of the experiments showed also that the obtained average shear stress was above most of the values found in previous conducted studies, which may be explained by consolidation effects in the reservoirs. Additional conducted vane strength measurements have been carried out in situ. The in the field obtained vane strength values were set in relation to the critical shear stresses derived by the experimental tests from the laboratory and to data from a previous conducted study to develop a new relation function. This function may be used in future studies for a rough estimation of the critical shear stress, based on in situ measured vane strength values.
2017-06-01
assigned to the individual study. The same is done in case only two people or one person show(s) up. Storing of large data files: When preparing...AWARD NUMBER: W81XWH-15-1-0042 TITLE: Psychobiological Assessment & Enhancement of Team Cohesion and Psychological Resilience in ROTC Cadets...4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with
Numerical Implementation of the Cohesive Soil Bounding Surface Plasticity Model. Volume I.
1983-02-01
AD-R24 866 NUMERICAL IMPLEMENTATION OF THE COHESIVE SOIL BOUNDING 1/2 SURFACE PLASTICITY ..(U) CALIFORNIA UNIV DAVIS DEPT OF CIVIL ENGINEERING L R...a study of various numerical means for implementing the bounding surface plasticity model for cohesive soils is presented. A comparison is made of... Plasticity Models 17 3.4 Selection Of Methods For Comparison 17 3.5 Theory 20 3.5.1 Solution Methods 20 3.5.2 Reduction Of The Number Of Equation
Effect of fertiliser on functional properties of flour from four rice varieties grown in Sri Lanka.
Gunaratne, Anil; Sirisena, Nihal; Ratnayaka, Upul Kumari; Ratnayaka, Jennet; Kong, Xiangli; Vidhana Arachchi, Lal Peruma; Corke, Harold
2011-05-01
Fertiliser is an essential agro-chemical input in modern rice farming. Fertiliser affects the grain quality and yield of rice. Although much research has been carried out to investigate the influence of fertiliser (recommended NPK addition) on yield and quality of rice grain, little is known about the effect of fertiliser on thermal, pasting, gelling and retrogradation properties of rice flour. The aim of this study was to investigate the influence of recommended fertilisation on functional properties of rice flour from four popular high yielding rice varieties grown in Sri Lanka. Fertiliser (recommended NPK addition) increased the protein content but reduced the apparent amylose content in rice flour except in BG 357. Swelling power and amylose leaching were decreased by fertilizer. [corrected] Pasting onset temperature, cold paste viscosity and setback were increased but peak viscosity and granular breakdown decreased. In response to the fertiliser application, gelatinisation peak temperature was reduced in all varieties except BG 300. However, compared to pasting properties, gelatinisation parameters were not much affected by fertilisation. The extent of amylopectin retrogradation was decreased by fertiliser in BG 305 and BG 352 but unchanged in the other two varieties. Except in BG 305, fertiliser reduced the gel hardness of rice flour but increased the gel cohesiveness. It is apparent that the increased protein and reduced amylose content caused by fertiliser affect the functional properties of rice flour. Copyright © 2011 Society of Chemical Industry.
NASA Astrophysics Data System (ADS)
Muntaha, M.
2017-11-01
Indonesia, which located in tropical region, continuously undergoes wetting and drying cycles due to the changeable seasons. An important role in activating the clay minerals on tropical residual soils is the main factor that affects the static and dynamic properties, such as: volume change, soil suction and dynamic modulus. The purpose of this paper is to evaluate the effect of drying-wetting cycles repetition on volume change, soil suction and mechanical characteristics of natural and stabilization of residual soils from Jawa Timur - Indonesia. The natural undisturbed and stabilized residual soil sample was naturally and gradually dried up with air to 25%, 50%, 75%, and 100 % of the initial water content. The wetting processes were carried out with the gradual increment water content of 25 %(wsat - wi), 50 %(wsat - wi), 75 %(wsat - wi), up to 100 %(wsat - wi). The Direct Shear test is used to measure the mechanic properties, and Whatman filter paper No. 42 is used to measure the soil suction. The drying-wetting processes were carried out for 1, 2, 4, and 6 cycles. The laboratory test results showed that, the void ratio decreased, the unit weight, cohesion and the internal friction angle were increasing due to stabilization. Drying-wetting cycle repetition reduces void ratio, negative pore-water pressure, cohesion and internal friction angle of natural and stabilized soils. Briefly, the decreased of mechanical soil properties was proven from the physical properties change observation.
Team Orientations, Interpersonal Relations, and Team Success
ERIC Educational Resources Information Center
Nixon, Howard L.
1976-01-01
Contradictions in post research on the concepts of "cohesiveness" and team success seem to arise from the ways in which cohesiveness is measured and the nature of the teams investigated in each study. (MB)
Cohesiveness in Financial News and its Relation to Market Volatility
Piškorec, Matija; Antulov-Fantulin, Nino; Novak, Petra Kralj; Mozetič, Igor; Grčar, Miha; Vodenska, Irena; Šmuc, Tomislav
2014-01-01
Motivated by recent financial crises, significant research efforts have been put into studying contagion effects and herding behaviour in financial markets. Much less has been said regarding the influence of financial news on financial markets. We propose a novel measure of collective behaviour based on financial news on the Web, the News Cohesiveness Index (NCI), and we demonstrate that the index can be used as a financial market volatility indicator. We evaluate the NCI using financial documents from large Web news sources on a daily basis from October 2011 to July 2013 and analyse the interplay between financial markets and finance-related news. We hypothesise that strong cohesion in financial news reflects movements in the financial markets. Our results indicate that cohesiveness in financial news is highly correlated with and driven by volatility in financial markets. PMID:24849598
Barr, Simone C; Hanson, Rochelle; Begle, Angela M; Kilpatrick, Dean G; Saunders, Benjamin; Resnick, Heidi; Amstadter, Ananda
2012-01-01
Witnessed community violence has been linked to a number of internalizing and externalizing problems in adolescents. Guided by Cicchetti and Lynch's (1993) ecological-transactional model, this study aimed to examine the impact that family-level factors had on negative outcomes associated with witnessed community violence. Using a nationally representative sample, we explored the moderational role of family cohesion in the relationship between witnessing community violence and delinquent behavior while taking demographic variables into account. Results from the investigation suggested that low levels of family cohesion were predictive of delinquency after controlling for race, gender, past delinquency, and direct trauma. In addition, the findings suggested that family cohesion moderated the impact of witnessed community violence on future delinquent behavior. Future directions for research and implications for practice were also discussed.
Particle Engineering Via Mechanical Dry Coating in the Design of Pharmaceutical Solid Dosage Forms.
Qu, Li; Morton, David A V; Zhou, Qi Tony
2015-01-01
Cohesive powders are problematic in the manufacturing of pharmaceutical solid dosage forms because they exhibit poor flowability, fluidization and aerosolization. These undesirable bulk properties of cohesive powders represent a fundamental challenge in the design of efficient pharmaceutical manufacturing processes. Recently, mechanical dry coating has attracted increasing attention as it can improve the bulk properties of cohesive powders in a cheaper, simpler, safer and more environment-friendly way than the existing solvent-based counterparts. In this review, mechanical dry coating techniques are outlined and their potential applications in formulation and manufacturing of pharmaceutical solid dosage forms are discussed. Reported data from the literature have shown that mechanical dry coating holds promise for the design of superior pharmaceutical solid formulations or manufacturing processes by engineering the interfaces of cohesive powders in an efficient and economical way.
Perceived Neighborhood Social Cohesion and Myocardial Infarction
Kim, Eric S.; Hawes, Armani M.; Smith, Jacqui
2015-01-01
Background The main strategy for alleviating heart disease has been to target individuals and encourage them to change their health behaviors. Though important, emphasis on individuals has diverted focus and responsibility away from neighborhood characteristics, which also strongly influence people’s behaviors. Although a growing body of research has repeatedly demonstrated strong associations between neighborhood characteristics and cardiovascular health, it has typically focused on negative neighborhood characteristics. Only a few studies have examined the potential health enhancing effects of positive neighborhood characteristics, such as perceived neighborhood social cohesion. Methods Using multiple logistic regression models, we tested whether higher perceived neighborhood social cohesion was associated with lower incidence of myocardial infarction. Prospective data from the Health and Retirement Study—a nationally representative panel study of American adults over the age of 50—were used to analyze 5,276 participants with no history of heart disease. Respondents were tracked for four years and analyses adjusted for relevant sociodemographic, behavioral, biological, and psychosocial factors. Results In a model that adjusted for age, gender, race, marital status, education, and total wealth, each standard deviation increase in perceived neighborhood social cohesion was associated with a 22% reduced odds of myocardial infarction (OR = 0.78, 95% CI, 0.63–0.94. The association between perceived neighborhood social cohesion and myocardial infarction remained even after adjusting for behavioral, biological, and psychosocial covariates. Conclusions Higher perceived neighborhood social cohesion may have a protective effect against myocardial infarction. PMID:25135074
Martin-Biggers, Jennifer; Quick, Virginia; Zhang, Man; Jin, Yanhong; Byrd-Bredbenner, Carol
2018-04-01
This study examined how food-related behaviours differed in mothers and their preschool children by levels of family functioning (cohesion and conflict) and household disorganization (chaos). A nationally representative sample of mothers of preschoolers completed an online survey assessing food-related behaviours of themselves and their children. Maternal and child diet, eating behaviours, and health status; household availability of fruits/vegetables, salty/fatty snacks, and sugar-sweetened beverages; family mealtime atmosphere; and family conflict, cohesion, and household chaos were assessed with valid, reliable scales. Cluster analyses assigned families into low, middle, and high conflict, cohesion, and chaos groups. Participants (n = 550) were 72% White, and 82% had some post-secondary education. Regression analysis examining the association of cluster grouping levels on diet-related behaviour measures revealed that positive home environments (i.e., low family conflict, high family cohesion, and low household chaos) were associated with healthier food-related behaviours (e.g., increased fruits/vegetables intake), whereas negative home environments (i.e., high family conflict, low family cohesion, and high household chaos) were associated with unhealthy food-related behaviours (e.g., greater % total calories from fat) even after controlling for sociodemographic and related behavioural factors. Findings suggest family functioning and household chaos are associated with food-related behaviours. This frequently overlooked component of family interaction may affect intervention outcomes and objectives of educational and interventional initiatives. © 2017 John Wiley & Sons Ltd.
Saccharomyces cerevisiae CTF18 and CTF4 Are Required for Sister Chromatid Cohesion
Hanna, Joseph S.; Kroll, Evgueny S.; Lundblad, Victoria; Spencer, Forrest A.
2001-01-01
CTF4 and CTF18 are required for high-fidelity chromosome segregation. Both exhibit genetic and physical ties to replication fork constituents. We find that absence of either CTF4 or CTF18 causes sister chromatid cohesion failure and leads to a preanaphase accumulation of cells that depends on the spindle assembly checkpoint. The physical and genetic interactions between CTF4, CTF18, and core components of replication fork complexes observed in this study and others suggest that both gene products act in association with the replication fork to facilitate sister chromatid cohesion. We find that Ctf18p, an RFC1-like protein, directly interacts with Rfc2p, Rfc3p, Rfc4p, and Rfc5p. However, Ctf18p is not a component of biochemically purified proliferating cell nuclear antigen loading RF-C, suggesting the presence of a discrete complex containing Ctf18p, Rfc2p, Rfc3p, Rfc4p, and Rfc5p. Recent identification and characterization of the budding yeast polymerase κ, encoded by TRF4, strongly supports a hypothesis that the DNA replication machinery is required for proper sister chromatid cohesion. Analogous to the polymerase switching role of the bacterial and human RF-C complexes, we propose that budding yeast RF-CCTF18 may be involved in a polymerase switch event that facilities sister chromatid cohesion. The requirement for CTF4 and CTF18 in robust cohesion identifies novel roles for replication accessory proteins in this process. PMID:11287619
Altabet, Y Elia; Fenley, Andreia L; Stillinger, Frank H; Debenedetti, Pablo G
2018-03-21
Particles with cohesive interactions display a tensile instability in the energy landscape at the Sastry density ρ S . The signature of this tensile limit is a minimum in the landscape equation of state, the pressure-density relationship of inherent structures sampled along a liquid isotherm. Our previous work [Y. E. Altabet, F. H. Stillinger, and P. G. Debenedetti, J. Chem. Phys. 145, 211905 (2016)] revisited the phenomenology of Sastry behavior and found that the evolution of the landscape equation of state with system size for particles with interactions typical of molecular liquids indicates the presence of an athermal first-order phase transition between homogeneous and fractured inherent structures, the latter containing several large voids. Here, we study how this tensile limit manifests itself for different interparticle cohesive strengths and identify two distinct regimes. Particles with sufficiently strong cohesion display an athermal first-order phase transition, consistent with our prior characterization. Weak cohesion also displays a tensile instability. However, the landscape equation of state for this regime is independent of system size, suggesting the absence of a first-order phase transition. An analysis of the voids suggests that yielding in the energy landscape of weakly cohesive systems is associated with the emergence of a highly interconnected network of small voids. While strongly cohesive systems transition from exclusively homogeneous to exclusively fractured configurations at ρ S in the thermodynamic limit, this interconnected network develops gradually, starting at ρ S , even at infinite system size.
Topographic Signatures of Meandering Rivers with Differences in Outer Bank Cohesion
NASA Astrophysics Data System (ADS)
Kelly, S. A.; Belmont, P.
2014-12-01
Within a given valley setting, interactions between river hydraulics, sediment, topography, and vegetation determine attributes of channel morphology, including planform, width and depth, slope, and bed and bank properties. These feedbacks also govern river behavior, including migration and avulsion. Bank cohesion, from the addition of fine sediment and/or vegetation has been recognized in flume experiments as a necessary component to create and maintain a meandering channel planform. Greater bank cohesion slows bank erosion, limiting the rate at which a river can adjust laterally and preventing so-called "runaway widening" to a braided state. Feedbacks of bank cohesion on channel hydraulics and sediment transport may thus produce distinct topographic signatures, or patterns in channel width, depth, and point bar transverse slope. We expect that in bends of greater outer bank cohesion the channel will be narrower, deeper, and bars will have greater transverse slopes. Only recently have we recognized that biotic processes may imprint distinct topographic signatures on the landscape. This study explores topographic signatures of three US rivers: the lower Minnesota River, near Mankato, MN, the Le Sueur River, south central MN, and the Fall River, Rocky Mountain National Park, CO. Each of these rivers has variability in outer bank cohesion, quantified based on geotechnical and vegetation properties, and in-channel topography, which was derived from rtkGPS and acoustic bathymetry surveys. We present methods for incorporating biophysical feedbacks into geomorphic transport laws so that models can better simulate the spatial patterns and variability of topographic signatures.
NASA Astrophysics Data System (ADS)
Altabet, Y. Elia; Fenley, Andreia L.; Stillinger, Frank H.; Debenedetti, Pablo G.
2018-03-01
Particles with cohesive interactions display a tensile instability in the energy landscape at the Sastry density ρS. The signature of this tensile limit is a minimum in the landscape equation of state, the pressure-density relationship of inherent structures sampled along a liquid isotherm. Our previous work [Y. E. Altabet, F. H. Stillinger, and P. G. Debenedetti, J. Chem. Phys. 145, 211905 (2016)] revisited the phenomenology of Sastry behavior and found that the evolution of the landscape equation of state with system size for particles with interactions typical of molecular liquids indicates the presence of an athermal first-order phase transition between homogeneous and fractured inherent structures, the latter containing several large voids. Here, we study how this tensile limit manifests itself for different interparticle cohesive strengths and identify two distinct regimes. Particles with sufficiently strong cohesion display an athermal first-order phase transition, consistent with our prior characterization. Weak cohesion also displays a tensile instability. However, the landscape equation of state for this regime is independent of system size, suggesting the absence of a first-order phase transition. An analysis of the voids suggests that yielding in the energy landscape of weakly cohesive systems is associated with the emergence of a highly interconnected network of small voids. While strongly cohesive systems transition from exclusively homogeneous to exclusively fractured configurations at ρS in the thermodynamic limit, this interconnected network develops gradually, starting at ρS, even at infinite system size.
Haven, Erin L; Manangan, Christen N; Sparrow, Joanne K; Wilson, Beverly J
2014-04-01
This study examined associations between parent-child interactions and the development of social skills in 42 children (21 typically developing and 21 with autism spectrum disorders) between the ages of 3 years, 0 months and 6 years, 11 months. We expected that positive parent-child interaction qualities would be related to children's social skills and would mediate the negative relation between children's developmental status (typical development vs autism spectrum disorders) and social skills. Videotapes of parents and children during a 5-min wordless book task were coded for parent positive affect and emotional support as well as parent-child cohesiveness. Emotional support and cohesiveness were significantly related to children's social skills, such that higher emotional support and cohesiveness were associated with higher social skills, R (2) = .29, p = .02, and R (2) = .38, p = .002, respectively. Additionally, cohesiveness mediated the relation between children's developmental status and social skills. These findings suggest that parent emotional support and cohesiveness between parents and children positively influence children's social skills. Parent positive affect was unrelated to social skills. Implications of these findings for social skills interventions are discussed, particularly for young children with autism spectrum disorders.
Family Cohesion, Stigma, and Quality of Life in Dyads of Children With Epilepsy and Their Parents.
Mendes, Teresa P; Crespo, Carla A; Austin, Joan K
2017-07-01
To examine the mediating role of stigma on the links between family cohesion and quality of life (QoL) in children with epilepsy and their parents. Participants were 192 families attending three Portuguese public hospitals. Children and parents completed self-report measures of family cohesion, stigma, QoL, and health-related QoL (HRQoL). Neurologists assessed clinical variables. Structural equation modeling within the framework of the actor-partner interdependence model was used. The final model showed a good fit to the data, explaining 43% and 35% of the QoL outcomes of children and parents, respectively. Family cohesion was positively linked to QoL outcomes, directly for children and parents, and indirectly for children only, by way of negative links with perceived stigma. At the dyadic level, parents' perceptions of family cohesion were positively associated with children's HRQoL. A routine screening of those patients experiencing poorer HRQoL should include the assessment of family relationships and stigma. © The Author 2017. Published by Oxford University Press on behalf of the Society of Pediatric Psychology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com
Hong, Seunghye; Zhang, Wei; Walton, Emily
2014-06-01
This study examines the associations of neighborhood ethnic density and poverty with social cohesion and self-rated mental health among Asian Americans and Latinos. Path analysis is employed to analyze data from the 2002-2003 National Latino and Asian American Study (NLAAS) and the 2000 U.S. Census (N = 2095 Asian Americans living in N = 259 neighborhoods; N = 2554 Latinos living in N = 317 neighborhoods). Findings reveal that neighborhood ethnic density relates to poor mental health in both groups. Social cohesion partially mediates that structural relationship, but is positively related to ethnic density among Latinos and negatively related to ethnic density among Asian Americans. Although higher neighborhood poverty is negatively associated with mental health for both groups, the relationship does not hold in the path models after accounting for social cohesion and covariates. Furthermore, social cohesion fully mediates the association between neighborhood poverty and mental health among Latinos. This study highlights the necessity of reconceptualizing existing theories of social relationships to reflect complex and nuanced mechanisms linking neighborhood structure and mental health for diverse racial and ethnic groups. Copyright © 2014 Elsevier Ltd. All rights reserved.
Fall, Kelsey A.; Harris, Courtney K.; Friedrichs, Carl T.; Rinehimer, J. Paul; Sherwood, Christopher R.
2014-01-01
The Community Sediment Transport Modeling System (CSTMS) cohesive bed sub-model that accounts for erosion, deposition, consolidation, and swelling was implemented in a three-dimensional domain to represent the York River estuary, Virginia. The objectives of this paper are to (1) describe the application of the three-dimensional hydrodynamic York Cohesive Bed Model, (2) compare calculations to observations, and (3) investigate sensitivities of the cohesive bed sub-model to user-defined parameters. Model results for summer 2007 showed good agreement with tidal-phase averaged estimates of sediment concentration, bed stress, and current velocity derived from Acoustic Doppler Velocimeter (ADV) field measurements. An important step in implementing the cohesive bed model was specification of both the initial and equilibrium critical shear stress profiles, in addition to choosing other parameters like the consolidation and swelling timescales. This model promises to be a useful tool for investigating the fundamental controls on bed erodibility and settling velocity in the York River, a classical muddy estuary, provided that appropriate data exists to inform the choice of model parameters.
Positive parenting, family cohesion, and child social competence among immigrant Latino families.
Leidy, Melinda S; Guerra, Nancy G; Toro, Rosa I
2010-06-01
The relation between positive parenting, family cohesion, and child social competence was examined among Latino families (predominantly from Mexico) who were recent immigrants to the United States. A mixed method study was conducted, including both pre- and post-test self-reported surveys (9-month interval) and qualitative data from focus groups. A total of 282 parents and 282 children (ages 9-12) participated in the survey study. Results at post-test follow-up indicated that family cohesion predicted improvements in child social problem-solving skills and social self-efficacy, and positive parenting predicted improvements in child social self-efficacy. A total of 12 mothers participated in the focus group study that was designed to explore barriers to positive parenting and family cohesion in this population. Results from focus groups revealed four major themes impacting parenting and family cohesion: (a) acculturation differences between parents and children and the resulting power imbalance; (b) difficulty getting involved in their child's education; (c) loss of extended family; and (d) discrimination against immigrants and legal status. The implications for family support programs for immigrant Latino families and their children are discussed. (c) 2010 APA, all rights reserved.
ERIC Educational Resources Information Center
McCarty, Robbie V.
2000-01-01
Introduces an activity for fifth grade elementary students on water, cohesion, and adhesion. Provides a list of necessary materials and includes a checklist for performance based assessment. Recommends follow up experiments for testing cohesive property with different liquids. (YDS)
Adult meerkats modify close call rate in the presence of pups.
Wyman, Megan T; Rivers, Pearl R; Muller, Coline; Toni, Pauline; Manser, Marta B
2017-06-01
In animals, signaling behavior is often context-dependent, with variation in the probability of emitting certain signals dependent on fitness advantages. Senders may adjust signaling rate depending on receiver identity, presence of audiences, or noise masking the signal, all of which can affect the benefits and costs of signal production. In the cooperative breeding meerkat Suricata suricatta , group members emit soft contact calls, termed as "close calls", while foraging in order to maintain group cohesion. Here, we investigated how the close calling rate during foraging was affected by the presence of pups, that produce continuous, noisy begging calls as they follow older group members. Adults decreased their overall close call rate substantially when pups were foraging with the group in comparison to periods when no pups were present. We suggest this decrease was likely due to a masking effect of the loud begging calls, which makes the close call function of maintaining group cohesion partly redundant as the centrally located begging calls can be used instead to maintain cohesion. There was some support that adults use close calls strategically to attract specific pups based on fitness advantages, that is, as the philopatric sex, females should call more than males and more to female pups than male pups. Dominant females called more than dominant males when a pup was in close proximity, while subordinates showed no sex-based differences. The sex of the nearest pup did not affect the calling rate of adults. The study shows that meerkats modify their close call production depending on benefits gained from calling and provides an example of the flexible use of one calling system in the presence of another, here contact calls versus begging calls, within the same species.
Improvement of flow and bulk density of pharmaceutical powders using surface modification.
Jallo, Laila J; Ghoroi, Chinmay; Gurumurthy, Lakxmi; Patel, Utsav; Davé, Rajesh N
2012-02-28
Improvement in flow and bulk density, the two most important properties that determine the ease with which pharmaceutical powders can be handled, stored and processed, is done through surface modification. A limited design of experiment was conducted to establish a standardized dry coating procedure that limits the extent of powder attrition, while providing the most consistent improvement in angle of repose (AOR). The magnetically assisted impaction coating (MAIC) was considered as a model dry-coater for pharmaceutical powders; ibuprofen, acetaminophen, and ascorbic acid. Dry coated drug powders were characterized by AOR, particle size as a function of dispersion pressure, particle size distribution, conditioned bulk density (CBD), Carr index (CI), flow function coefficient (FFC), cohesion coefficient using different instruments, including a shear cell in the Freeman FT4 powder rheometer, and Hansen flowability index. Substantial improvement was observed in all the measured properties after dry coating relative to the uncoated powders, such that each powder moved from a poorer to a better flow classification and showed improved dispersion. The material intrinsic property such as cohesion, plotted as a function of particle size, gave a trend similar to those of bulk flow properties, AOR and CI. Property improvement is also illustrated in a phase map of inverse cohesion (or FFC) as a function of bulk density, which also indicated a significant positive shift due to dry coating. It is hoped that such phase maps are useful in manufacturing decisions regarding the need for dry coating, which will allow moving from wet granulation to roller compaction or to direct compression based formulations. Copyright © 2011 Elsevier B.V. All rights reserved.
Understanding the difference in cohesive energies between alpha and beta tin in DFT calculations
DOE Office of Scientific and Technical Information (OSTI.GOV)
Legrain, Fleur; Manzhos, Sergei, E-mail: mpemanzh@nus.edu.sg
2016-04-15
The transition temperature between the low-temperature alpha phase of tin to beta tin is close to the room temperature (T{sub αβ} = 13{sup 0}C), and the difference in cohesive energy of the two phases at 0 K of about ΔE{sub coh} =0.02 eV/atom is at the limit of the accuracy of DFT (density functional theory) with available exchange-correlation functionals. It is however critically important to model the relative phase energies correctly for any reasonable description of phenomena and technologies involving these phases, for example, the performance of tin electrodes in electrochemical batteries. Here, we show that several commonly used andmore » converged DFT setups using the most practical and widely used PBE functional result in ΔE{sub coh} ≈0.04 eV/atom, with different types of basis sets and with different models of core electrons (all-electron or pseudopotentials of different types), which leads to a significant overestimation of T{sub αβ}. We show that this is due to the errors in relative positions of s and p –like bands, which, combined with different populations of these bands in α and β Sn, leads to overstabilization of alpha tin. We show that this error can be effectively corrected by applying a Hubbard +U correction to s –like states, whereby correct cohesive energies of both α and β Sn can be obtained with the same computational scheme. We quantify for the first time the effects of anharmonicity on ΔE{sub coh} and find that it is negligible.« less
On crack initiation in notched, cross-plied polymer matrix composites
NASA Astrophysics Data System (ADS)
Yang, Q. D.; Schesser, D.; Niess, M.; Wright, P.; Mavrogordato, M. N.; Sinclair, I.; Spearing, S. M.; Cox, B. N.
2015-05-01
The physics of crack initiation in a polymer matrix composite are investigated by varying the modeling choices made in simulations and comparing the resulting predictions with high-resolution in situ images of cracks. Experimental data were acquired using synchrotron-radiation computed tomography (SRCT) at a resolution on the order of 1 μm, which provides detailed measurement of the location, shape, and size of small cracks, as well as the crack opening and shear displacements. These data prove sufficient to discriminate among competing physical descriptions of crack initiation. Simulations are executed with a high-fidelity formulation, the augmented finite element method (A-FEM), which permits consideration of coupled damage mechanisms, including both discrete cracks and fine-scale continuum damage. The discrete cracks are assumed to be nonlinear fracture events, governed by reasonably general mixed-mode cohesive laws. Crack initiation is described in terms of strength parameters within the cohesive laws, so that the cohesive law provides a unified model for crack initiation and growth. Whereas the cracks investigated are typically 1 mm or less in length, the fine-scale continuum damage refers to irreversible matrix deformation occurring over gauge lengths extending down to the fiber diameter (0.007 mm). We find that the location and far-field stress for crack initiation are predicted accurately only if the variations of local stress within plies and in the presence of stress concentrators (notches, etc.) are explicitly computed and used in initiation criteria; stress redistribution due to matrix nonlinearity that occurs prior to crack initiation is accounted for; and a mixed-mode criterion is used for crack initiation. If these factors are not all considered, which is the case for commonly used failure criteria, predictions of the location and far-field stress for initiation are not accurate.
Eriksson, Ulrika; Asplund, Kenneth; Sellström, Eva
2010-01-01
People are influenced by the neighborhood in which they live. The neighborhood may be particularly important for children's wellbeing because of the constraints it imposes on their patterns of daily activities. Furthermore, the neighborhood is a central context for social development, being a place where children form networks and learn social skills and values. The aim of this study was to describe how social capital in the neighborhood is perceived by children living in rural areas, and to reveal what this adds to their sense of wellbeing. The study had a descriptive research design with a qualitative approach. Seven single-sex focus group interviews were conducted with children the in 6th grade (aged 11-12 years). Data were analyzed using deductive content analysis. The children perceived a lack of social capital due to environmental and social constraints in their everyday lives. However, their wellbeing was enhanced by strong cohesion in the neighborhood. In addition, settings such as the school, the natural environment, and sporting associations were highly valued and emerged as crucial factors for enhancing the children's wellbeing. The spatial isolation that characterizes rural areas created a special context of social network structures, cohesion and trust, but was also a breeding ground for exclusion and social control. The stories revealed paradoxical feelings of living in a good and safe area that simultaneously felt isolated and restricted. From a rural perspective, this study reveals the complexity of the children's perceptions of their social environment, and the ways in which these perceptions have both positive and negative effects on wellbeing. The results highlight how important it is for health professionals in rural areas to consider the complex influence of bonding social capital on children's wellbeing, and to be aware that it can promote exclusion as well as cohesion.
NASA Astrophysics Data System (ADS)
Zhang, Fan; Zhao, Jianjian; Hu, Dawei; Skoczylas, Frederic; Shao, Jianfu
2018-03-01
High-temperature treatment may cause changes in physical and mechanical properties of rocks. Temperature changing rate (heating, cooling and both of them) plays an important role in those changes. Thermal conductivity tests, ultrasonic pulse velocity tests, gas permeability tests and triaxial compression tests are performed on granite samples after a heating and rapid cooling treatment in order to characterize the changes in physical and mechanical properties. Seven levels of temperature (from 25 to 900 °C) are used. It is found that the physical and mechanical properties of granite are significantly deteriorated by the thermal treatment. The porosity shows a significant increase from 1.19% at the initial state to 6.13% for samples heated to 900 °C. The increase in porosity is mainly due to three factors: (1) a large number of microcracks caused by the rapid cooling rate; (2) the mineral transformation of granite through high-temperature heating and water-cooling process; (3) the rapid cooling process causes the mineral particles to weaken. As the temperature of treatment increases, the thermal conductivity and P-wave velocity decrease while the gas permeability increases. Below 200 °C, the elastic modulus and cohesion increase with temperature increasing. Between 200 and 500 °C, the elastic modulus and cohesion have no obvious change with temperature. Beyond 500 °C, as the temperature increases, the elastic modulus and cohesion obviously decrease and the decreasing rate becomes slower with the increase in confining pressure. Poisson's ratio and internal frictional coefficient have no obvious change as the temperature increases. Moreover, there is a transition from a brittle to ductile behavior when the temperature becomes high. At 900 °C, the granite shows an obvious elastic-plastic behavior.
1983-09-01
and status systems (Albanese, 1981; Griffin, 1982; Lott & Lott, 1971). Group cohesiveness and norms, according to Wallace and Szilagyi (1982), were the... Wallace & Szilagyi , 1982): 1. The major difference between high and low cohesive groups would be how closely members conform to group norms ; and 2. Group...performance would be influenced not only by cohesiveness, but also by the level or strength of group norms. Research by Wallace and Szilagyi (1982
On the identification of cohesive parameters for printed metal-polymer interfaces
NASA Astrophysics Data System (ADS)
Heinrich, Felix; Langner, Hauke H.; Lammering, Rolf
2017-05-01
The mechanical behavior of printed electronics on fiber reinforced composites is investigated. A methodology based on cohesive zone models is employed, considering interfacial strengths, stiffnesses and critical strain energy release rates. A double cantilever beam test and an end notched flexure test are carried out to experimentally determine critical strain energy release rates under fracture modes I and II. Numerical simulations are performed in Abaqus 6.13 to model both tests. Applying the simulations, an inverse parameter identification is run to determine the full set of cohesive parameters.
Ferrelli, Rita Maria
2015-10-01
EUROsociAL is a European Union program for social cohesion in Latin America. The main objective of this essay is to present the conceptual elements underpinning the activities of the EUROsociAL program in the health thematic area, with special attention to their equity aspects. It considers the concepts of social cohesion, equity in health, and the relationship between the two in EUROsociAL, and addresses monitoring of equity in health as a basis of action toward improvement focusing on social determinants of health.
Eckhardt, Nadin; Polansky, Leo; Boesch, Christophe
2015-02-01
Group living animals can exhibit fission-fusion behavior whereby individuals temporarily separate to reduce the costs of living in large groups. Primates living in groups with fission-fusion dynamics face numerous challenges in maintaining spatial cohesion, especially in environments with limited visibility. Here we investigated the spatial cohesion of adult male chimpanzees (Pan troglodytes verus) living in Taï National Park, Côte d'Ivoire, to better understand the mechanisms by which individuals maintain group cohesion during fission-fusion events. Over a 3-year period, we simultaneously tracked the movements of 2-4 males for 4-12 hr on up to 12 consecutive days using handheld GPS devices that recorded locations at one-minute intervals. Analyses of the male's inter-individual distance (IID) showed that the maximum, median, and mean IID values across all observations were 7.2 km, 73 m, and 483 m, respectively. These males (a) had maximum daily IID values below the limits of auditory communication (<1 km) for 63% of the observation time, (b) remained out of visual range (≥100 m) for 46% of observation time, and (c) remained within auditory range for 70% of the time when they were in different parties. We compared the observed distribution of IIDs with a random distribution obtained from permutations of the individuals' travel paths using Kolmogorov-Smirnov tests. Observation IID values were significantly smaller than those generated by the permutation procedure. We conclude that these male chimpanzees actively maintain cohesion when out of sight, and that auditory communication is one likely mechanism by which they do so. We discuss mechanisms by which chimpanzees may maintain the level of cohesion observed. This study provides a first analysis of spatial group cohesion over large distances in forest chimpanzees using high-resolution tracking, and illustrates the utility of such data for quantifying socio-ecological processes in primate ecology. © 2014 Wiley Periodicals, Inc.
Stroeymeyt, Nathalie; Giurfa, Martin; Franks, Nigel R
2010-09-29
Successful collective decision-making depends on groups of animals being able to make accurate choices while maintaining group cohesion. However, increasing accuracy and/or cohesion usually decreases decision speed and vice-versa. Such trade-offs are widespread in animal decision-making and result in various decision-making strategies that emphasize either speed or accuracy, depending on the context. Speed-accuracy trade-offs have been the object of many theoretical investigations, but these studies did not consider the possible effects of previous experience and/or knowledge of individuals on such trade-offs. In this study, we investigated how previous knowledge of their environment may affect emigration speed, nest choice and colony cohesion in emigrations of the house-hunting ant Temnothorax albipennis, a collective decision-making process subject to a classical speed-accuracy trade-off. Colonies allowed to explore a high quality nest site for one week before they were forced to emigrate found that nest and accepted it faster than emigrating naïve colonies. This resulted in increased speed in single choice emigrations and higher colony cohesion in binary choice emigrations. Additionally, colonies allowed to explore both high and low quality nest sites for one week prior to emigration remained more cohesive, made more accurate decisions and emigrated faster than emigrating naïve colonies. These results show that colonies gather and store information about available nest sites while their nest is still intact, and later retrieve and use this information when they need to emigrate. This improves colony performance. Early gathering of information for later use is therefore an effective strategy allowing T. albipennis colonies to improve simultaneously all aspects of the decision-making process--i.e. speed, accuracy and cohesion--and partly circumvent the speed-accuracy trade-off classically observed during emigrations. These findings should be taken into account in future studies on speed-accuracy trade-offs.
Transport mechanisms of contaminants released from fine sediment in rivers
NASA Astrophysics Data System (ADS)
Cheng, Pengda; Zhu, Hongwei; Zhong, Baochang; Wang, Daozeng
2015-12-01
Contaminants released from sediment into rivers are one of the main problems to study in environmental hydrodynamics. For contaminants released into the overlying water under different hydrodynamic conditions, the mechanical mechanisms involved can be roughly divided into convective diffusion, molecular diffusion, and adsorption/desorption. Because of the obvious environmental influence of fine sediment (D_{90}= 0.06 mm), non-cohesive fine sediment, and cohesive fine sediment are researched in this paper, and phosphorus is chosen for a typical adsorption of a contaminant. Through theoretical analysis of the contaminant release process, according to different hydraulic conditions, the contaminant release coupling mathematical model can be established by the N-S equation, the Darcy equation, the solute transport equation, and the adsorption/desorption equation. Then, the experiments are completed in an open water flume. The simulation results and experimental results show that convective diffusion dominates the contaminant release both in non-cohesive and cohesive fine sediment after their suspension, and that they contribute more than 90 % of the total release. Molecular diffusion and desorption have more of a contribution for contaminant release from unsuspended sediment. In unsuspension sediment, convective diffusion is about 10-50 times larger than molecular diffusion during the initial stages under high velocity; it is close to molecular diffusion in the later stages. Convective diffusion is about 6 times larger than molecular diffusion during the initial stages under low velocity, it is about a quarter of molecular diffusion in later stages, and has a similar level with desorption/adsorption. In unsuspended sediment, a seepage boundary layer exists below the water-sediment interface, and various release mechanisms in that layer mostly dominate the contaminant release process. In non-cohesive fine sediment, the depth of that layer increases linearly with shear stress. In cohesive fine sediment, the range seepage boundary is different from that in non-cohesive sediment, and that phenomenon is more obvious under a lower shear stress.
Leader behaviors, group cohesion, and participation in a walking group program
Izumi, Betty T.; Schulz, Amy J.; Mentz, Graciela; Israel, Barbara A.; Sand, Sharon L.; Reyes, Angela G.; Hoston, Bernadine; Richardson, Dawn; Gamboa, Cindy; Rowe, Zachary; Diaz, Goya
2015-01-01
Background Fewer than half of all U.S. adults meet the 2008 Physical Activity Guidelines. Leader behaviors and group cohesion have been associated with increased participation or adherence in sports team and exercise class settings. Physical activity interventions in community settings that encompass these factors may enhance intervention adherence. Purpose To examine the impact of Community Health Promoter leader behaviors and group cohesion on participation in a walking group intervention among racially/ethnically diverse adults in low-to-moderate income communities in Detroit, Mich. Design Data for the current study were drawn from the Walk Your Heart to Health (WYHH) data set. WYHH was a multi-site cluster randomized controlled study with a lagged intervention and outcome measurements at baseline, four, eight, and 32 weeks. Pooled survey data from both intervention arms is used for the current study. Data were analyzed between August 2013 and October 2014. Setting/participants A total of 603 non-Hispanic Black, non-Hispanic White, and Hispanic adults across five cohorts that began the 32-week WYHH intervention between March 2009 and October 2011. Intervention A 32-week long walking group program hosted by community- and faith-based organizations and facilitated by Community Health Promoters. Walking groups met three times per week for 90-minutes per session. To promote participation in or adherence to WYHH, Community Health Promoters used evidence-based strategies to facilitate group cohesion. Group members assumed increasing leadership responsibility for facilitating sessions over time. Main outcome measures Participation in WYHH as measured by consistency of attendance. Results Community Health Promoter leader behaviors were positively associated with participation in WYHH. Social but not task cohesion was significantly associated with consistent participation. Social cohesion may mediate the relationship between leader behaviors and walking group participation. Conclusions Providing leaders with training to build socially cohesive groups may help motivate individuals to continue participation in community-based physical activity programs. PMID:26094226
Alliance and group cohesion in relationship education.
Owen, Jesse; Antle, Becky; Barbee, Anita
2013-09-01
Relationship education programs have been shown as an effective way to increase relationship functioning. There is less known about how process factors, such as alliance with the leader or group dynamics, affect outcomes in these interventions. We examined group cohesion and alliance with the leader in a relationship education program tailored for individuals. Specifically, we examined whether participants' ratings (n = 126) of the group cohesion and alliance with the leader were associated with changes in relationship adjustment, relationship confidence, and communication quality from pre- to postintervention. The results demonstrated that participants' perceptions of the cohesion among the members in their relationship education group, but not the leader-participant alliance, made a significant contribution to the changes in participants' relationship functioning. These results suggest that the group dynamics among the members in the group are important ingredients in relationship education. Implications for relationship programs are provided. © FPI, Inc.
NASA Astrophysics Data System (ADS)
Yuhendar, A. H.; Wusqa, U.; Kartiko, R. D.; Raya, N. R.; Misbahudin
2016-05-01
Large-scale landslide occurred in Margamukti village, Pangalengan, Bandung Regency, West Java Province, Indonesia. The landslide damaged geothermal gas pipeline along 300 m in Wayang Windu Geothermal Field. Based on field observation, landslide occured in rotational sliding movement. Laboratory analysis were conducted to obtain the characteristics of the soil. Based on the condition of the landslide in this area, the Factor of Safety can be simulated by the soil mechanics approach. Factor of safety analysis based on soil cohesion and internal friction angle was conducted using manual sensitivity analysis for back analysis. The analysis resulted soil cohesion in critical condition (FS<1) is 6.01 kPa. This value is smaller than cohesion of undisturbed slope soil sample. Water from rainfall is the most important instability factors in research area. Because it decreases cohesion in soils and increases weight and pore water pressure in granular media.
Mundt, Marlon P; Antonaccio, Olena P; French, Michael T; Zakletskaia, Larissa I
2017-08-01
Weapon-related violent crime is a serious, complex, and multifaceted public health problem. The present study uses data from Waves I and III of Add Health (n = 10,482, 54% female) to examine how friendship group integration and cohesion in adolescence (ages 12-19) is associated with weapon-related criminal activity as a young adult (ages 18-26). Results indicate that greater cohesion in friendship groups is associated with significantly lower weapon-related criminal activity in young adulthood. In addition, for adolescent girls, a greater number of close friendship ties-an indicator of friendship group integration-is associated with less weapon-related criminal activity in young adulthood. These findings suggest that school-based initiatives to facilitate inclusive and cohesive adolescent peer communities may be an effective strategy to curb weapon-related criminal activity in young adulthood.
Characterization of mode 1 and mixed-mode failure of adhesive bonds between composite adherends
NASA Technical Reports Server (NTRS)
Mall, S.; Johnson, W. S.
1985-01-01
A combined experimental and analytical investigation of an adhesively bonded composite joint was conducted to characterize both the static and fatigue beyond growth mechanism under mode 1 and mixed-mode 1 and 2 loadings. Two bonded systems were studied: graphite/epoxy adherends bonded with EC 3445 and FM-300 adhesives. For each bonded system, two specimen types were tested: a double-cantilever-beam specimen for mode 1 loading and a cracked-lapshear specimen for mixed-mode 1 and 2 loading. In all specimens tested, failure occurred in the form of debond growth. Debonding always occurred in a cohesive manner with EC 3445 adhesive. The FM-300 adhesive debonded in a cohesive manner under mixed-mode 1 and 2 loading, but in a cohesive, adhesive, or combined cohesive and adhesive manner under mode 1 loading. Total strain-energy release rate appeared to be the driving parameter for debond growth under static and fatigue loadings.
Effect of size on bulk and surface cohesion energy of metallic nano-particles
NASA Astrophysics Data System (ADS)
Yaghmaee, M. S.; Shokri, B.
2007-04-01
The knowledge of nano-material properties not only helps us to understand the extreme behaviour of small-scale materials better (expected to be different from what we observe from their bulk value) but also helps us to analyse and design new advanced functionalized materials through different nano technologies. Among these fundamental properties, the cohesion (binding) energy mainly describes most behaviours of materials in different environments. In this work, we discuss this fundamental property through a nano-thermodynamical approach using two algorithms, where in the first approach the size dependence of the inner (bulk) cohesion energy is studied, and in the second approach the surface cohesion energy is considered too. The results, which are presented through a computational demonstration (for four different metals: Al, Ga, W and Ag), can be compared with some experimental values for W metallic nano-particles.
Structure of the Pds5-Scc1 Complex and Implications for Cohesin Function.
Muir, Kyle W; Kschonsak, Marc; Li, Yan; Metz, Jutta; Haering, Christian H; Panne, Daniel
2016-03-08
Sister chromatid cohesion is a fundamental prerequisite to faithful genome segregation. Cohesion is precisely regulated by accessory factors that modulate the stability with which the cohesin complex embraces chromosomes. One of these factors, Pds5, engages cohesin through Scc1 and is both a facilitator of cohesion, and, conversely also mediates the release of cohesin from chromatin. We present here the crystal structure of a complex between budding yeast Pds5 and Scc1, thus elucidating the molecular basis of Pds5 function. Pds5 forms an elongated HEAT repeat that binds to Scc1 via a conserved surface patch. We demonstrate that the integrity of the Pds5-Scc1 interface is indispensable for the recruitment of Pds5 to cohesin, and that its abrogation results in loss of sister chromatid cohesion and cell viability. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.
Effects of Parent and Family Characteristics on Treatment Outcome of Anxious Children
Victor, Andrea M.; Bernat, Debra H.; Bernstein, Gail A.; Layne, Ann E.
2008-01-01
This study examines relations between family functioning, parenting stress, parental psychopathology, and treatment outcome. Participants included 61 children (ages 7 to 11) with features or diagnoses of separation anxiety disorder, generalized anxiety disorder, and/or social phobia. Treatment conditions included group cognitive behavioral therapy (CBT) and no-treatment control. Higher family cohesion at baseline was associated with significantly greater decreases in child anxiety at posttreatment for participants who received CBT, while no association was found for the no-treatment control participants. Parenting stress and parental psychopathology were not associated with treatment outcome for either condition. Post hoc analyses examining relations between family cohesion, parenting stress, and parental psychopathology showed that parents from families low in cohesion reported significantly higher levels of parenting stress and psychopathology compared to parents from families high in cohesion. These results will facilitate development and implementation of effective interventions with anxious children. PMID:17161582
Noncontact Cohesive Swimming of Bacteria in Two-Dimensional Liquid Films.
Li, Ye; Zhai, He; Sanchez, Sandra; Kearns, Daniel B; Wu, Yilin
2017-07-07
Bacterial swimming in confined two-dimensional environments is ubiquitous in nature and in clinical settings. Characterizing individual interactions between swimming bacteria in 2D confinement will help to understand diverse microbial processes, such as bacterial swarming and biofilm formation. Here we report a novel motion pattern displayed by flagellated bacteria in 2D confinement: When two nearby cells align their moving directions, they tend to engage in cohesive swimming without direct cell body contact, as a result of hydrodynamic interaction but not flagellar intertwining. We further found that cells in cohesive swimming move with higher directional persistence, which can increase the effective diffusivity of cells by ∼3 times as predicted by computational modeling. As a conserved behavior for peritrichously flagellated bacteria, cohesive swimming in 2D confinement may be key to collective motion and self-organization in bacterial swarms; it may also promote bacterial dispersal in unsaturated soils and in interstitial space during infections.
Spatializing Open Data for the Assessment and the Improvement of Territorial and Social Cohesion
NASA Astrophysics Data System (ADS)
Scorza, F.; Las Casas, G. B.; Murgante, B.
2016-09-01
An integrated place-based approach for the improvement of territorial and social cohesion is the new instance for planning disciplines, coming from EU New Cohesion Policies. This paper considers the territorial impact assessment of regional development policies as a precondition in order to develop balanced and effective operative programs at national and regional levels. The contribution of `open data' appears to be mature in order to support this application and in this paper we present a spatial analysis technique for the evaluation of EU funds effects at territorial level, starting from open data by Open Cohesion. The application is focused on internal areas of Basilicata Region: Agri river Valley. A complex contest, where environmental and agricultural traditional vocations conflict with a recent development of oil extraction industries. Conclusions concern further applications and perspectives to improve and support regional development planning considering the exploitation of open data sources and spatial analysis.
Juang, Linda P; Alvarez, Alvin A
2010-12-01
We examined racial/ethnic discrimination experiences of Chinese American adolescents to determine how discrimination is linked to poor adjustment (i.e., loneliness, anxiety, and somatization) and how the context of the family can buffer or exacerbate these links. We collected survey data from 181 Chinese American adolescents and their parents in Northern California. We conducted hierarchical regression analyses to examine main effects and 2-way interactions of perceived discrimination with family conflict and family cohesion. Discrimination was related to poorer adjustment in terms of loneliness, anxiety, and somatization, but family conflict and cohesion modified these relations. Greater family conflict exacerbated the negative effects of discrimination, and greater family cohesion buffered the negative effects of discrimination. Our findings highlight the importance of identifying family-level moderators to help adolescents and their families handle experiences of discrimination.
Barr, Simone C.; Hanson, Rochelle; Begle, Angela M.; Kilpatrick, Dean G.; Saunders, Benjamin; Resnick, Heidi; Amstadter, Ananda
2014-01-01
Witnessed community violence has been linked to a number of internalizing and externalizing problems in adolescents. Guided by Cicchetti and Lynch’s (1993) ecological-transactional model, this study aimed to examine the impact that family-level factors had on negative outcomes associated with witnessed community violence. Using a nationally representative sample, we explored the moderational role of family cohesion in the relationship between witnessing community violence and delinquent behavior while taking demographic variables into account. Results from the investigation suggested that low levels of family cohesion were predictive of delinquency after controlling for race, gender, past delinquency, and direct trauma. In addition, the findings suggested that family cohesion moderated the impact of witnessed community violence on future delinquent behavior. Future directions for research and implications for practice were also discussed. PMID:21920873
Belkin, Aaron
2013-01-01
For almost 20 years, gay rights advocates and defenders of military anti-gay discrimination engaged in a phony debate about whether allowing open service would undermine unit cohesion. To be sure, a preponderance of evidence showed that open service would not undermine cohesion, and the repeal of don't ask, don't tell (DADT) required advocates to prevail on that point in the court of public opinion. But concerns about cohesion were never the basis of opposition to open service. Rather, opposition was a modern incarnation of the politics of paranoia, a dangerous tradition in American history. Acknowledging that DADT had nothing to do with cohesion and that military leaders allowed the armed forces to be implicated in the politics of paranoia could facilitate disabling paranoia as the basis for other political projects such as anti-immigrant xenophobia. For a video on DADT and paranoia, search for "Donnelly Belkin DADT" on YoutTube.