Prediction of resilient modulus from soil index properties.

DOT National Transportation Integrated Search

2004-11-01

Subgrade soil characterization in terms of Resilient Modulus (MR) has become crucial for pavement design. For a new : design, MR values are generally obtained by conducting repeated load triaxial tests on reconstituted/undisturbed cylindrical : speci...

Prediction of resilient modulus from soil index properties

DOT National Transportation Integrated Search

2004-11-01

Subgrade soil characterization in terms of Resilient Modulus (MR) has become crucial for pavement design. For a new design, MR values are generally obtained by conducting repeated load triaxial tests on reconstituted/undisturbed cylindrical specimens...

Estimation of subgrade resilient modulus using the unconfined compression test.

DOT National Transportation Integrated Search

2014-11-01

To facilitate pavement design, the new proposed mechanistic-empirical pavement design guide recommends the resilient : modulus to characterize subgrade soil and its use for calculating pavement responses attributable to traffic and environmental : lo...

Resilient Modulus of Freeze-Thaw Affected Granular Soils for Pavement Design and Evaluation. Part 2. Field Validation Tests at Winchendon, Massachusetts, Test Sections,

DTIC Science & Technology

1986-10-01

AD-AI?5 394 RESILIENT MODULUS OF FREEZE-THAN AFFECTED GRANULAR 1/1 SOILS FOR PAVEMENT DES . .( U) COLD REGIONS RESEARCH AND ENGINEERING LAB HANOVER NH...Chamberlain, who had a major role in the de - velopment of the laboratory testing techniques; Glenn Durell, who conducted the resilient modulus testing; and...notorious. In areas of seasonal moisture tension, and the stresses imposed in the frost the supporting capacity of subgrade soils and triaxial tests. For

Improving accuracy of unbound resilient modulus testing

DOT National Transportation Integrated Search

1997-07-01

The P46 Laboratory Startup and Quality Control Procedure was developed to ensure the accuracy and reliability of the resilient modulus data produced while testing soil and aggregate materials using closed-loop servo-hydraulic systems. It was develope...

Repeatability of testing procedures for resilient modulus and fatigue.

DOT National Transportation Integrated Search

1989-04-01

Extensive use of diametral resilient modulus and fatigue testing is made by the Oregon State Highway Division to evaluate asphaltic concrete materials. Test results on similar materials (e.g., adjacent field cores), however, often indicate a poor lev...

Resilient modulus testing of materials from MN/Road : phase 1

DOT National Transportation Integrated Search

1996-09-01

The U.S. Army Cold Regions Research and Engineering Laboratory (CRREL) conducted resilient modulus tests on materials from the MN/ROAD test site for the Minnesota Department of Transportation. Materials tested included samples of the lean clay subgra...

Comparative evaluation of subgrade resilient modulus from non-destructive, in-situ, and laboratory methods.

DOT National Transportation Integrated Search

2007-08-01

Field and laboratory testing programs were conducted to develop models that predict the resilient modulus of subgrade soils from : the test results of DCP, CIMCPT, FWD, Dynaflect, and soil properties. The field testing program included DCP, CIMCPT, F...

Study of LTPP laboratory resilient modulus test data and response characteristics.

DOT National Transportation Integrated Search

2002-10-01

The resilient modulus of every unbound structural layer of the Long Term Pavement Performance (LTPP) Specific Pavement and : General Pavement Studies Test Sections is being measured in the laboratory using LTPP test protocol P46. A total of 2,014 : r...

Investigation of the applicability of intrusion technology to estimate the resilient modulus of subgrade soil.

DOT National Transportation Integrated Search

2000-04-01

An innovative and simple approach is presented for estimation of the resilient modulus of subgrade soils utilizing the cone penetration test. Field and laboratory testing programs were carried out at seven sites that comprise three common soil types ...

Mechanical evaluation of quad-helix appliance made of low-nickel stainless steel wire.

PubMed

dos Santos, Rogério Lacerda; Pithon, Matheus Melo

2013-01-01

The objective of this study was to test the hypothesis that there is no difference between stainless steel and low-nickel stainless steel wires as regards mechanical behavior. Force, resilience, and elastic modulus produced by Quad-helix appliances made of 0.032-inch and 0.036-inch wires were evaluated. Sixty Quad-helix appliances were made, thirty for each type of alloy, being fifteen for each wire thickness, 0.032-in and 0.036-in. All the archwires were submitted to mechanical compression test using an EMIC DL-10000 machine simulating activations of 4, 6, 9, and 12 mm. Analysis of variance (ANOVA) with multiple comparisons and Tukey's test were used (p < 0.05) to assess force, resilience, and elastic modulus. Statistically significant difference in the forces generated, resilience and elastic modulus were found between the 0.032-in and 0.036-in thicknesses (p < 0.05). Appliances made of low-nickel stainless steel alloy had force, resilience, and elastic modulus similar to those made of stainless steel alloy.

Development of models to estimate the subgrade and subbase layers' resilient modulus from in situ devices test results for construction control.

DOT National Transportation Integrated Search

2008-04-01

The objective of this study was to develop resilient modulus prediction models for possible application in the quality control/quality assurance (QC/QA) procedures during and after the construction of pavement layers. Field and laboratory testing pro...

Extended monitoring and analysis of moisture-temperature data

DOT National Transportation Integrated Search

2001-10-01

The performance of asphalt concrete pavements is in part affected by the seasonal variations of the resilient modulus of the AC layer and of the subgrade soil. To determine the variation of these parameters throughout Ohio, nine moisture-temperature-...

Development of models to estimate the subgrade and subbase layers' resilient modulus from in-situ devices test results for construction control.

DOT National Transportation Integrated Search

2009-05-01

The primary objective of this research was to develop models that predict the resilient modulus of cohesive and granular soils from the test results of various in-situ test devices for possible application in QA/QC during construction of pavement str...

Pavement subgrade MR design values for Michigan's seasonal changes : appendices.

DOT National Transportation Integrated Search

2009-07-22

The resilient modulus (MR) of roadbed soil plays an integral role in the design of pavement systems. Currently, the various regions of the Michigan Department of Transportation (MDOT) use different procedures to determine the MR values. Most of these...

Extended monitoring and analysis of moisture temperature data : [executive summary].

DOT National Transportation Integrated Search

2001-01-01

The performance of asphalt concrete pavements is in part affected by the seasonal variations of the resilient modulus of the AC layer and of the subgrade soil. To determine the variation of these parameters throughout Ohio, nine moisture-temperature-...

The Effect Of Aggregate Angularity On Base Course Performance

DOT National Transportation Integrated Search

2001-09-01

The Vermont Agency of Transportation (VAOT) conducted a two-phase study to quantify the resilient modulus and strength characteristics of its subbase material. In Phase 1, a literature review was done to determine the various methods available for in...

Analysis and evaluation of methods for backcalculation of Mr values : volume 1 : research report : final report.

DOT National Transportation Integrated Search

1993-01-01

Use of the 1986 AASHTO Design Guide requires accurate estimates of the resilient modulus of flexible pavement materials. Traditionally, these properties have been determined from either laboratory testing or by backcalculation from deflection data. S...

Pavement subgrade MR design values for Michigan's seasonal changes : table E5.

DOT National Transportation Integrated Search

2010-06-22

The resilient modulus (MR) of roadbed soil plays an integral role in the design of pavement systems. Currently, the various regions of the Michigan Department of Transportation (MDOT) use different procedures to determine the MR values. Most of these...

Pavement subgrade MR design values for Michigan's seasonal changes : table E4.

DOT National Transportation Integrated Search

2009-07-22

The resilient modulus (MR) of roadbed soil plays an integral role in the design of pavement systems. Currently, the various regions of the Michigan Department of Transportation (MDOT) use different procedures to determine the MR values. Most of these...

Pavement subgrade MR design values for Michigan's seasonal changes : final report.

DOT National Transportation Integrated Search

2009-07-22

The resilient modulus (MR) of roadbed soil plays an integral role in the design of pavement systems. Currently, the : various regions of the Michigan Department of Transportation (MDOT) use different procedures to determine the : MR values. Most of t...

Monitoring and analysis of data obtained from moisture temperature recording stations : executive summary.

DOT National Transportation Integrated Search

2001-09-01

The performance of asphalt concrete pavements is in part affected by the seasonal variations of the resilient modulus of the AC layer and of the subgrade soil. To determine the variation of these parameters throughout Ohio, seven moisture-temperature...

Monitoring and analysis of data obtained from moisture temperature recording stations : final report.

DOT National Transportation Integrated Search

2001-09-01

The performance of asphalt concrete pavements is in part affected by the seasonal variations of the resilient modulus of the AC layer and of the subgrade soil. To determine the variation of these parameters throughout Ohio, seven moisture-temperature...

Base course resilient modulus for the mechanistic-empirical pavement design guide.

DOT National Transportation Integrated Search

2011-11-01

The Mechanistic-Empirical Pavement Design Guidelines (MEPDG) recommend use of modulus in lieu of structural number for base layer thickness design. Modulus is nonlinear with respect to effective confinement stress, loading strain, and moisture. For d...

Introduction of fracture resistance to the design and evaluation of open graded friction courses in Florida : final report, July 2009.

DOT National Transportation Integrated Search

2009-07-01

A dog-bone direct tension test (DBDT) to accurately determine tensile properties of asphalt concrete, : including OGFC, was conceived, developed and validated. Resilient modulus, creep, and strength tests : were performed at multiple temperatures on ...

Determination by the falling weight deflectometer of the in-situ subgrade resilient modulus and effective structural number for I-77 in Virginia.

DOT National Transportation Integrated Search

2007-01-01

The Virginia Department of Transportation (VDOT) manages approximately 27,000 lane-miles of interstate and primary roadways, of which interstate pavements comprise approximately 5,000 lane-miles. These pavements consist of flexible, rigid, and compos...

Characterization of time-dependent changes in strength and stiffness of Florida base materials : final report, October 2008.

DOT National Transportation Integrated Search

2008-10-01

Resilient modulus and Youngs modulus are parameters increasingly used to fundamentally characterize the behavior : of pavement materials both in the laboratory and in the field. This study documents the small-strain Youngs modulus : and larger-...

Effects of Kaolin Clay on the Mechanical Properties of Asphaltic Concrete AC14

NASA Astrophysics Data System (ADS)

Abdullah, M. E.; Ramadhansyah, P. J.; Rafsanjani, M. H.; Norhidayah, A. H.; Yaacob, H.; Hainin, M. R.; Warid, M. N. Mohd; Satar, M. K. I. Mohd; Aziz, Md Maniruzzaman A.; Mashros, N.

2018-04-01

This study investigated the effect of kaolin clay on the mechanical properties of asphaltic concrete AC14 through Marshall Stability, resilient modulus, and dynamic creep tests. Four replacement levels of kaolin clay (2%, 4%, 6%, and 8% by weight of the binder) were considered. Kaolin clay functioned as an effective filler replacement material to increase the mechanical properties of asphalt mixtures. Asphaltic concrete with 2% to 4% kaolin clay replacement level exhibited excellent performance with good stability, resilient modulus, and creep stiffness.

Falling weight deflectometer for estimating subgrade resilient moduli.

DOT National Transportation Integrated Search

2003-12-01

Subgrade soil characterization expressed in terms of resilient modulus, MR, has become crucial for pavement design. For : new pavement design, MR values are generally obtained by conducting repeated load triaxial tests on reconstituted/undisturbed : ...

Performance of asphalt mixture incorporating recycled waste

NASA Astrophysics Data System (ADS)

Hamid, Nor Baizura; Abdullah, Mohd Ezree; Sanik, Mohd Erwan; Mokhtar, Mardiha; Kaamin, Masiri; Raduan, Rasyidah; Ramli, Mohd Zakwan

2017-12-01

Nowadays, the amount of premix waste was increased every year, especially at the batching plants. Normally, the waste materials will be discarded without doing any innovative and effective research about those materials. This situation has become one of the global concerns due to the increasing number of premix waste produced every year. Therefore, the aim of this study is to evaluate the performance of hot mix asphalt (HMA) using premix waste on improving asphalt mixture fatigue behaviour. The method used in this study was Superpave mix design method. The sample conducted in this study were 0%, 10%, 20%, 30%, and 100% of premix waste respectively. For a binder test, the laboratory test conducted were penetration test, softening test and thin film oven test while for the performance test were resilient modulus test and indirect tensile fatigue test. From the laboratory test, the resilient modulus test was conducted with two different temperature which was 25°C and 40°C. The result from that test was 20% of premix waste had higher resilient modulus at that two different temperatures compared to another samples. From that test also shown that the sample at the lower temperature which was 25°C has higher resilient modulus compared to the temperature of 40°C. Indirect tensile fatigue test showed that the 30% of premix waste sample was suitable for the modified asphalt mixture with referring to the maximum deformation and strain for comparison control, 10%,20%, and 100% of premix waste samples. So, it can be concluded that premix waste inhibits great potential as road construction material and suitable for repeated traffic loading.

Effect of moisture content and dry unit weight on the resilient modulus of subgrade soils predicted by cone penetration test.

DOT National Transportation Integrated Search

2002-06-01

The objective of this study was to investigate the effect of moisture content and dry unit weight on the resilient characteristics of subgrade soil predicted by the cone penetration test. An experimental program was conducted in which cone penetratio...

Deflection of Resilient Materials for Reduction of Floor Impact Sound

PubMed Central

Lee, Jung-Yoon; Kim, Jong-Mun

2014-01-01

Recently, many residents living in apartment buildings in Korea have been bothered by noise coming from the houses above. In order to reduce noise pollution, communities are increasingly imposing bylaws, including the limitation of floor impact sound, minimum thickness of floors, and floor soundproofing solutions. This research effort focused specifically on the deflection of resilient materials in the floor sound insulation systems of apartment houses. The experimental program involved conducting twenty-seven material tests and ten sound insulation floating concrete floor specimens. Two main parameters were considered in the experimental investigation: the seven types of resilient materials and the location of the loading point. The structural behavior of sound insulation floor floating was predicted using the Winkler method. The experimental and analytical results indicated that the cracking strength of the floating concrete floor significantly increased with increasing the tangent modulus of resilient material. The deflection of the floating concrete floor loaded at the side of the specimen was much greater than that of the floating concrete floor loaded at the center of the specimen. The Winkler model considering the effect of modulus of resilient materials was able to accurately predict the cracking strength of the floating concrete floor. PMID:25574491

Deflection of resilient materials for reduction of floor impact sound.

PubMed

Lee, Jung-Yoon; Kim, Jong-Mun

2014-01-01

Recently, many residents living in apartment buildings in Korea have been bothered by noise coming from the houses above. In order to reduce noise pollution, communities are increasingly imposing bylaws, including the limitation of floor impact sound, minimum thickness of floors, and floor soundproofing solutions. This research effort focused specifically on the deflection of resilient materials in the floor sound insulation systems of apartment houses. The experimental program involved conducting twenty-seven material tests and ten sound insulation floating concrete floor specimens. Two main parameters were considered in the experimental investigation: the seven types of resilient materials and the location of the loading point. The structural behavior of sound insulation floor floating was predicted using the Winkler method. The experimental and analytical results indicated that the cracking strength of the floating concrete floor significantly increased with increasing the tangent modulus of resilient material. The deflection of the floating concrete floor loaded at the side of the specimen was much greater than that of the floating concrete floor loaded at the center of the specimen. The Winkler model considering the effect of modulus of resilient materials was able to accurately predict the cracking strength of the floating concrete floor.

Tendon material properties vary and are interdependent among turkey hindlimb muscles

PubMed Central

Matson, Andrew; Konow, Nicolai; Miller, Samuel; Konow, Pernille P.; Roberts, Thomas J.

2012-01-01

SUMMARY The material properties of a tendon affect its ability to store and return elastic energy, resist damage, provide mechanical feedback and amplify or attenuate muscle power. While the structural properties of a tendon are known to respond to a variety of stimuli, the extent to which material properties vary among individual muscles remains unclear. We studied the tendons of six different muscles in the hindlimb of Eastern wild turkeys to determine whether there was variation in elastic modulus, ultimate tensile strength and resilience. A hydraulic testing machine was used to measure tendon force during quasi-static lengthening, and a stress–strain curve was constructed. There was substantial variation in tendon material properties among different muscles. Average elastic modulus differed significantly between some tendons, and values for the six different tendons varied nearly twofold, from 829±140 to 1479±106 MPa. Tendons were stretched to failure, and the stress at failure, or ultimate tensile stress, was taken as a lower-limit estimate of tendon strength. Breaking tests for four of the tendons revealed significant variation in ultimate tensile stress, ranging from 66.83±14.34 to 112.37±9.39 MPa. Resilience, or the fraction of energy returned in cyclic length changes was generally high, and one of the four tendons tested was significantly different in resilience from the other tendons (range: 90.65±0.83 to 94.02±0.71%). An analysis of correlation between material properties revealed a positive relationship between ultimate tensile strength and elastic modulus (r2=0.79). Specifically, stiffer tendons were stronger, and we suggest that this correlation results from a constrained value of breaking strain, which did not vary significantly among tendons. This finding suggests an interdependence of material properties that may have a structural basis and may explain some adaptive responses observed in studies of tendon plasticity. PMID:22771746

Tendon material properties vary and are interdependent among turkey hindlimb muscles.

PubMed

Matson, Andrew; Konow, Nicolai; Miller, Samuel; Konow, Pernille P; Roberts, Thomas J

2012-10-15

The material properties of a tendon affect its ability to store and return elastic energy, resist damage, provide mechanical feedback and amplify or attenuate muscle power. While the structural properties of a tendon are known to respond to a variety of stimuli, the extent to which material properties vary among individual muscles remains unclear. We studied the tendons of six different muscles in the hindlimb of Eastern wild turkeys to determine whether there was variation in elastic modulus, ultimate tensile strength and resilience. A hydraulic testing machine was used to measure tendon force during quasi-static lengthening, and a stress-strain curve was constructed. There was substantial variation in tendon material properties among different muscles. Average elastic modulus differed significantly between some tendons, and values for the six different tendons varied nearly twofold, from 829±140 to 1479±106 MPa. Tendons were stretched to failure, and the stress at failure, or ultimate tensile stress, was taken as a lower-limit estimate of tendon strength. Breaking tests for four of the tendons revealed significant variation in ultimate tensile stress, ranging from 66.83±14.34 to 112.37±9.39 MPa. Resilience, or the fraction of energy returned in cyclic length changes was generally high, and one of the four tendons tested was significantly different in resilience from the other tendons (range: 90.65±0.83 to 94.02±0.71%). An analysis of correlation between material properties revealed a positive relationship between ultimate tensile strength and elastic modulus (r(2)=0.79). Specifically, stiffer tendons were stronger, and we suggest that this correlation results from a constrained value of breaking strain, which did not vary significantly among tendons. This finding suggests an interdependence of material properties that may have a structural basis and may explain some adaptive responses observed in studies of tendon plasticity.

Solid impingement erosion mechanisms and characterization of erosion resistance of ductile metals

NASA Technical Reports Server (NTRS)

Rao, V. P.; Buckley, D. H.

1982-01-01

Experimental results pertaining to spherical glass bead and angular crushed glass particle impingement are presented. A concept of energy adsorption to explain the failure of material is proposed. The erosion characteristics of several pure metals were correlated with the proposed energy parameters and with other properties. Correlations of erosion and material properties were also carried out with these materials to study the effect of the angle of impingement. Analyses of extensive erosion data indicate that surface energy, strain energy, melting point, bulk modulus, hardness, ultimate resilience, atomic volume and product of linear coefficient of thermal expansion, bulk modulus, and temperature rise required for melting, and ultimate resilience, and hardness exhibit the best correlations. It appears that both energy and thermal properties contribute to the total erosion.

Subgrade characterization for highway pavement design.

DOT National Transportation Integrated Search

2000-12-01

Subgrade soil characterization expressed in terms of Resilient Modulus (MR) has become crucial for pavement design. For a new design, MR : values are generally obtained by conducting repeated triaxial tests on reconstituted/undisturbed cylindrical sp...

Performance Evaluation of Hot Mix Asphalt with Different Proportions of RAP Content

NASA Astrophysics Data System (ADS)

Kamil Arshad, Ahmad; Awang, Haryati; Shaffie, Ekarizan; Hashim, Wardati; Rahman, Zanariah Abd

2018-03-01

Reclaimed Asphalt Pavement (RAP) is old asphalt pavement that has been removed from a road by milling or full depth removal. The use of RAP in hot mix asphalt (HMA) eliminates the need to dispose old asphalt pavements and conserves asphalt binders and aggregates, resulting in significant cost savings and benefits to society. This paper presents a study on HMA with different RAP proportions carried out to evaluate the volumetric properties and performance of asphalt mixes containing different proportions of RAP. Marshall Mix Design Method was used to produce control mix (0% RAP) and asphalt mixes containing 15% RAP, 25% RAP and 35% RAP in accordance with Specifications for Road Works of Public Works Department, Malaysia for AC14 dense graded asphalt gradation. Volumetric analysis was performed to ensure that the result is compliance with specification requirements. The resilient modulus test was performed to measure the stiffness of the mixes while the Modified Lottman test was conducted to evaluate the moisture susceptibility of these mixes. The Hamburg wheel tracking test was used to evaluate the rutting performance of these mixes. The results obtained showed that there were no substantial difference in Marshall Properties, moisture susceptibility, resilient modulus and rutting resistance between asphalt mixes with RAP and the control mix. The test results indicated that recycled mixes performed as good as the performance of conventional HMA in terms of moisture susceptibility and resilient modulus. It is recommended that further research be carried out for asphalt mixes containing more than 35% RAP material.

Reconstruction of railroads and highways with in-situ reclamation materials.

DOT National Transportation Integrated Search

2011-03-01

The resilient modulus and plastic deformation of recycled roadway materials with and without fly ash stabilization were characterized using a large-scale model experiment (LSME). Stabilization of recycled pavement materials (RPM) and road surface gra...

Laboratory tests for hot-mix asphalt characterization in Virginia.

DOT National Transportation Integrated Search

2005-01-01

This project reviewed existing laboratory methods for accurately describing the constitutive behavior of the mixes used in the Commonwealth of Virginia. Indirect tensile (IDT) strength, resilient modulus, static creep in the IDT and uniaxial modes, f...

Portable FWD (Prima 100) for in-situ subgrade evaluation.

DOT National Transportation Integrated Search

2006-06-01

Subgrade soil characterization measured in terms of resilient modulus, MR, has been a prerequisite for pavement design. For new pavement design, MR is obtained by conducting repeated load triaxial tests on reconstituted/undisturbed cylindrical specim...

Performance of asphaltic concrete incorporating styrene butadiene rubber subjected to varying aging condition

NASA Astrophysics Data System (ADS)

Salah, Faisal Mohammed; Jaya, Ramadhansyah Putra; Mohamed, Azman; Hassan, Norhidayah Abdul; Rosni, Nurul Najihah Mad; Mohamed, Abdullahi Ali; Agussabti

2017-12-01

The influence of styrene butadiene rubber (SBR) on asphaltic concrete properties at different aging conditions was presented in this study. These aging conditions were named as un-aged, short-term, and long-term aging. The conventional asphalt binder of penetration grade 60/70 was used in this work. Four different levels of SBR addition were employed (i.e., 0 %, 1 %, 3 %, and 5 % by binder weight). Asphalt concrete mixes were prepared at selected optimum asphalt content (5 %). The performance was evaluated based on Marshall Stability, resilient modulus, and dynamic creep tests. Results indicated the improving stability and permanent deformation characteristics that the mixes modified with SBR polymer have under aging conditions. The result also showed that the stability, resilient modulus, and dynamic creep tests have the highest rates compared to the short-term aging and un-aged samples. Thus, the use of 5 % SBR can produce more durable asphalt concrete mixtures with better serviceability.

Performance of Hot Mix Asphalt Mixture Incorporating Kenaf Fibre

NASA Astrophysics Data System (ADS)

Hainin, M. R.; Idham, M. K.; Yaro, N. S. A.; Hussein, S. O. A. E.; Warid, M. N. M.; Mohamed, A.; Naqibah, S. N.; Ramadhansyah, P. J.

2018-04-01

Kenaf fibre has been recognised to increase the strength of concrete, but its application in asphalt concrete is still unanswered. This research investigated the performance of Hot Mix Asphalt (HMA) incorporated with different percentages of kenaf fibre (0.1 %, 0.2% and 0.3% by weight of dry aggregate) in term of resilient modulus, rutting performance using Asphalt Pavement analyser (APA) and moisture damage using the Modified Lottman test (AASHTO-T283). The fibre was interweaved to a diameter of about 5-10 mm and length of 30 mm which is three times the nominal maximum aggregate size used in the mix. Asphaltic mixtures of asphalt concrete (AC) 10 were prepared and compacted using Marshall compactor which were subsequently tested to evaluate the resilient modulus and moisture susceptibility. Twelve cylindrical specimens (150mm diameter) from AC10, two control samples with two modified ones for each percentage of kenaf fibres compacted using Gyratory compactor were used for rutting test using APA. The laboratory results reveal that the addition of kenaf fibres slightly reduce the resilient modulus of the mixes and that asphaltic mix with 0.3% kenaf fibre can mitigate both rutting and moisture damage which makes the pavement more sustain to the loads applied even in the presence of water. 0.3% kenaf fibre content is considered to be the optimal content which had the least rut depth and the highest TSR of 81.07%. Based on grid analysis, addition of 0.3% kenaf fibre in asphaltic concrete was recommended in modifying the samples.

Characterization of unbound materials (soils/aggregates) for mechanistic-empirical pavement design guide.

DOT National Transportation Integrated Search

2009-02-01

The resilient modulus (MR) input parameters in the Mechanistic-Empirical Pavement Design Guide (MEPDG) program have a significant effect on the projected pavement performance. The MEPDG program uses three different levels of inputs depending on the d...

DOTD implements soil measuring device to increase life of pavements : fact sheet.

DOT National Transportation Integrated Search

2011-11-01

The resilient modulus (Mr) of : pavement materials and subgrades : is an important input parameter for : the design of pavement structures. : Highway agencies tried to seek : diff erent surrogates. Various empirical : correlations have been used to p...

Tube Suction Test for Evaluating

DOT National Transportation Integrated Search

2012-06-01

In a comprehensive laboratory study, different tests namely, unconfined compressive strength (UCS) at the end of freeze-thaw/wet-dry (F-T/W-D) cycles, resilient modulus (Mr) at the end of F-T/W-D cycles, vacuum saturation, tube suction, and moisture ...

Resilient modulus characterization of Alaskan granular base materials.

DOT National Transportation Integrated Search

2010-08-01

When spring comes to cold regions, the active layer (the top few feet of soil that freezes and thaws seasonally) thaws quickly, while : deeper soil remains frozen. The active layer becomes saturated with water from snowmelt that collects atop the fro...

Extended monitoring and analysis of moisture temperature data : research implementation plan.

DOT National Transportation Integrated Search

2006-12-07

Variations in the mechanical properties of materials of a flexible pavement affect its response to applied : loads in the form of deflections, stresses and stains. The resilient modulus of asphalt concrete and of fine : grained subgrade soil vary sea...

Effect of suction hysteresis on resilient modulus of fine-grained cohesionless soil.

DOT National Transportation Integrated Search

2010-07-30

The mechanical behavior of subgrade soil is influenced by the seasonal variations in moisture content. To better understand this behavior, it is crucial to study the relationship between soil moisture content and matric suction known as the Soil Wate...

Tube suction test for evaluating durability of cementitiously stabilized soils.

DOT National Transportation Integrated Search

2011-06-01

In a comprehensive laboratory study, different tests namely, unconfined compressive strength (UCS) at the end of freeze-thaw/wet-dry (F-T/W-D) cycles, resilient modulus (Mr) at the end of F-T/W-D cycles, vacuum saturation, tube suction, and moisture ...

Long-Term Pavement Performance Materials Characterization Program: Verification of Dynamic Test Systems with an Emphasis on Resilient Modulus

DOT National Transportation Integrated Search

2005-09-01

This document describes a procedure for verifying a dynamic testing system (closed-loop servohydraulic). The procedure is divided into three general phases: (1) electronic system performance verification, (2) calibration check and overall system perf...

Tube suction test for evaluating durability of cementitiously stabilized soils.

DOT National Transportation Integrated Search

2011-06-01

In a comprehensive laboratory study, different tests namely, unconfined compressive strength (UCS) at the end of freeze-thaw/wet-dry (FT/ : W-D) cycles, resilient modulus (Mr) at the end of F-T/W-D cycles, vacuum saturation, tube suction, and moistur...

Monitoring and analysis of data obtained from moisture temperature recording stations : research implementation plan.

DOT National Transportation Integrated Search

2001-09-01

Variations in the mechanical properties of materials of a flexible pavement affect its response to applied : loads in the form of deflections, stresses and stains. The resilient modulus of asphalt concrete and of fine : grained subgrade soil vary sea...

Comparison of the wear and flexural characteristics of flowable resin composites for posterior lesions.

PubMed

Sumino, Natsu; Tsubota, Keishi; Takamizawa, Toshiki; Shiratsuchi, Koji; Miyazaki, Masashi; Latta, Mark A

2013-01-01

To determine the localized wear and flexural properties of flowable resin composites for posterior lesions compared with universal resin composites produced by the same manufacturers. Ten specimens of each of three flowable resins, G-ænial Universal Flo, G-ænial Flo and Clearfil Majesty Flow, and the corresponding resin composite materials, Kalore and Clearfil Majesty Esthetics, were prepared in custom fixtures and subjected to 400,000 wear machine cycles to simulate localized wear. The total maximum depth and volume loss of the wear facets was calculated for each specimen using a profilometer. A three-point bending test was performed to determine the flexural strength, modulus of elasticity and resilience. Values were statistically compared using one-way analysis of variance (ANOVA) followed by Tukey's Honestly Significant Difference (HSD) test. The wear depth ranged from 58.3-126.9 m and the volumetric loss ranged from 0.019-0.049 mm(3), with significant differences observed between restorative materials. The wear depth of G-ænial Universal Flo was significantly smaller than those of the other resin composites tested. The flexural strengths and elastic modulus ranged from 90.5-135.1 MPa and from 4.7-7.6 GPa, respectively. A significantly greater flexural strength and higher elastic modulus was found for G-ænial Universal Flo than the other composites. The wear and mechanical properties of the flowable resin composites tested suggested improved performance compared with universal resin composites.

Resilient modulus and the fatigue properties of Kansas hot mix asphalt mixes

DOT National Transportation Integrated Search

2006-08-01

A new design guide for pavement structures, based on a mechanistic design method, could be adopted by AASHTO in the near future and will replace the current version used by KDOT in the structural design of flexible and rigid pavements. The mechanisti...

Polymerization Behavior and Mechanical Properties of High-Viscosity Bulk Fill and Low Shrinkage Resin Composites.

PubMed

Shibasaki, S; Takamizawa, T; Nojiri, K; Imai, A; Tsujimoto, A; Endo, H; Suzuki, S; Suda, S; Barkmeier, W W; Latta, M A; Miyazaki, M

The present study determined the mechanical properties and volumetric polymerization shrinkage of different categories of resin composite. Three high viscosity bulk fill resin composites were tested: Tetric EvoCeram Bulk Fill (TB, Ivoclar Vivadent), Filtek Bulk Fill posterior restorative (FB, 3M ESPE), and Sonic Fill (SF, Kerr Corp). Two low-shrinkage resin composites, Kalore (KL, GC Corp) and Filtek LS Posterior (LS, 3M ESPE), were used. Three conventional resin composites, Herculite Ultra (HU, Kerr Corp), Estelite ∑ Quick (EQ, Tokuyama Dental), and Filtek Supreme Ultra (SU, 3M ESPE), were used as comparison materials. Following ISO Specification 4049, six specimens for each resin composite were used to determine flexural strength, elastic modulus, and resilience. Volumetric polymerization shrinkage was determined using a water-filled dilatometer. Data were evaluated using analysis of variance followed by Tukey's honestly significant difference test (α=0.05). The flexural strength of the resin composites ranged from 115.4 to 148.1 MPa, the elastic modulus ranged from 5.6 to 13.4 GPa, and the resilience ranged from 0.70 to 1.0 MJ/m 3 . There were significant differences in flexural properties between the materials but no clear outliers. Volumetric changes as a function of time over a duration of 180 seconds depended on the type of resin composite. However, for all the resin composites, apart from LS, volumetric shrinkage began soon after the start of light irradiation, and a rapid decrease in volume during light irradiation followed by a slower decrease was observed. The low shrinkage resin composites KL and LS showed significantly lower volumetric shrinkage than the other tested materials at the measuring point of 180 seconds. In contrast, the three bulk fill resin composites showed higher volumetric change than the other resin composites. The findings from this study provide clinicians with valuable information regarding the mechanical properties and polymerization kinetics of these categories of current resin composite.

Design optimization of a radial functionally graded dental implant.

PubMed

Ichim, Paul I; Hu, Xiaozhi; Bazen, Jennifer J; Yi, Wei

2016-01-01

In this work, we use FEA to test the hypothesis that a low-modulus coating of a cylindrical zirconia dental implant would reduce the stresses in the peri-implant bone and we use design optimization and the rule of mixture to estimate the elastic modulus and the porosity of the coating that provides optimal stress shielding. We show that a low-modulus coating of a dental implant significantly reduces the maximum stresses in the peri-implant bone without affecting the average stresses thus creating a potentially favorable biomechanical environment. Our results suggest that a resilient coating is capable of reducing the maximum compressive and tensile stresses in the peri-implant bone by up to 50% and the average stresses in the peri-implant bone by up to 15%. We further show that a transitional gradient between the high-modulus core and the low-modulus coating is not necessary and for a considered zirconia/HA composite the optimal thickness of the coating is 100 µ with its optimal elastic at the lowest value considered of 45 GPa. © 2015 Wiley Periodicals, Inc.

Mechanical Components from Highly Recoverable, Low Apparent Modulus Materials

NASA Technical Reports Server (NTRS)

Padula, Santo, II (Inventor); Noebe, Ronald D. (Inventor); Stanford, Malcolm K. (Inventor); DellaCorte, Christopher (Inventor)

2015-01-01

A material for use as a mechanical component is formed of a superelastic intermetallic material having a low apparent modulus and a high hardness. The superelastic intermetallic material is conditioned to be dimensionally stable, devoid of any shape memory effect and have a stable superelastic response without irrecoverable deformation while exhibiting strains of at least 3%. The method of conditioning the superelastic intermetallic material is described. Another embodiment relates to lightweight materials known as ordered intermetallics that perform well in sliding wear applications using conventional liquid lubricants and are therefore suitable for resilient, high performance mechanical components such as gears and bearings.

Characterization of subgrade resilient modulus for Virginia soils and its correlation with the results of other soil tests.

DOT National Transportation Integrated Search

2008-01-01

In 2004, the Guide for the Mechanistic-Empirical Design of New & Rehabilitated Pavement Structures (MEPDG) was developed under NCHRP Project 1-37A to replace the currently used 1993 Guide for Design of Pavement Structures by the American Association ...

Development of a catalog of resilient modulus values for aggregate base for use with the mechanistic-empirical pavement design guide (MEPDG).

DOT National Transportation Integrated Search

2015-06-01

Base aggregate is one of the intermediate layers in a pavement system for both flexible and rigid surfaces. Characterization : of base aggregate is necessary for pavement thickness design. Many transportation agencies, including the Virginia Departme...

Resilient modulus and fatigue life characterization of asphalt concrete mixtures used in the Ohio Test Road : special student study

DOT National Transportation Integrated Search

1998-05-01

The performance of flexible and rigid pavements depends not only on the effects of traffic but also on environmental effects. As part of the Federal Highway Administration's (FHWA) Strategic Highway Research Program (SHRP), a test road was recently c...

Use of coal fly ash and other waste products in soil stabilization and road construction including non-destructive testing of roadways.

DOT National Transportation Integrated Search

2012-06-01

An extensive laboratory testing program was performed on subgrade soils stabilized using fly ash and : lime kiln dust. The laboratory program included measurements of: compaction curves, small strain elastic moduli, : resilient modulus (Mr), Briaud C...

Use of coal fly ash and other waste products in soil stabilization and road construction-including non-destructive testing of roadways.

DOT National Transportation Integrated Search

2012-02-01

An extensive laboratory testing program was performed on subgrade soils stabilized using fly ash and lime kiln dust. The laboratory : program included measurements of: compaction curves, small strain elastic moduli, resilient modulus (Mr), Briaud Com...

Mechanical properties of graphene and boronitrene

NASA Astrophysics Data System (ADS)

Andrew, R. C.; Mapasha, R. E.; Ukpong, A. M.; Chetty, N.

2012-03-01

We present an equation of state (EOS) that describes how the hydrostatic change in surface area is related to two-dimensional in-plane pressure (F) and yields the measure of a material's resilience to isotropic stretching (the layer modulus γ) as one of its fit parameters. We give results for the monolayer systems of graphene and boronitrene, and we also include results for Si, Ge, GeC, and SiC in the isostructural honeycomb structure for comparison. Our results show that, of the honeycomb structures, graphene is the most resilient to stretching with a value of γC = 206.6 N m-1, second is boronitrene with γBN = 177.0 N m-1, followed by γSiC = 116.5 N m-1, γGeC = 101.0 N m-1, γSi = 44.5 N m-1, and γGe = 29.6 N m-1. We calculate the Young's and shear moduli from the elastic constants and find that, in general, they rank according to the layer modulus. We also find that the calculated layer modulus matches the one obtained from the EOS. We use the EOS to predict the isotropic intrinsic strength of the various systems and find that, in general, the intrinsic stresses also rank according to the layer modulus. Graphene and boronitrene have comparable strengths with intrinsic stresses of 29.4 and 26.0 N m-1, respectively. We considered four graphene allotropes including pentaheptite and graphdiyne and find that pentaheptite has a value for γ comparable to graphene. We find a phase transition from graphene to graphdiyne at F = -7.0 N m-1. We also consider bilayer, trilayer, and four-layered graphene and find that the addition of extra layers results in a linear dependence of γ with F.

Evaluation of fatigue life of CRM-reinforced SMA and its relationship to dynamic stiffness.

PubMed

Mashaan, Nuha Salim; Karim, Mohamed Rehan; Abdel Aziz, Mahrez; Ibrahim, Mohd Rasdan; Katman, Herda Yati; Koting, Suhana

2014-01-01

Fatigue cracking is an essential problem of asphalt concrete that contributes to pavement damage. Although stone matrix asphalt (SMA) has significantly provided resistance to rutting failure, its resistance to fatigue failure is yet to be fully addressed. The aim of this study is to evaluate the effect of crumb rubber modifier (CRM) on stiffness and fatigue properties of SMA mixtures at optimum binder content, using four different modification levels, namely, 6%, 8%, 10%, and 12% CRM by weight of the bitumen. The testing undertaken on the asphalt mix comprises the dynamic stiffness (indirect tensile test), dynamic creep (repeated load creep), and fatigue test (indirect tensile fatigue test) at temperature of 25°C. The indirect tensile fatigue test was conducted at three different stress levels (200, 300, and 400 kPa). Experimental results indicate that CRM-reinforced SMA mixtures exhibit significantly higher fatigue life compared to the mixtures without CRM. Further, higher correlation coefficient was obtained between the fatigue life and resilient modulus as compared to permanent strain; thus resilient modulus might be a more reliable indicator in evaluating the fatigue life of asphalt mixture.

Fatigue behaviour of core-spun yarns containing filament by means of cyclic dynamic loading

NASA Astrophysics Data System (ADS)

Esin, S.; Osman, B.

2017-10-01

The behaviour of yarns under dynamic loading is important that leads to understand the growth characteristics which is exposed to repetitive loadings during usage of fabric made from these yarns. Fabric growth is undesirable property that originated from low resilience characteristics of fabric. In this study, the effects of the filament fineness and yarn linear density on fatigue behaviour of rigid-core spun yarns were determined. Cotton covered yarns containing different filament fineness of polyester (PET) draw textured yarns (DTY) (100d/36f, 100d/96f, 100d/144f, 100d/192f and 100d/333f) and yarn linear densities (37 tex, 30 tex, 25 tex and 21 tex) were manufactured by using a modified ring spinning system at the same spinning parameters. Repetitive loads were applied for 25 cycles at levels between 0.1 and 3 N. Dynamic modulus and dynamic strain of yarn samples were analyzed statistically. Results showed that filament fineness and yarn linear density have significance effect on dynamic modulus and dynamic strain after cyclic loading.

Asphalt Concrete for Cold Regions, A Comparative Laboratory Study and Analysis of Mixtures Containing Soft and Hard Grades of Asphalt Cement,

DTIC Science & Technology

1980-01-01

Justification January 1980 BY Distribution Availabilit CodesIAvail an~d/or Dist special Prepa red for DIRECTORATE OF MILITARY PROGRAMS OFFICE, CHIEF OF...of water on the resilient modulus of asphalt treated mixes. Proecedinfp 4. Asphalt concrete mixes using the Tilton aggregates Association of Asphalt

Durability of base courses with mineral-cement-emulsion mixes (MCEM)

NASA Astrophysics Data System (ADS)

Kukiełka, J.; Sybilski, D.

2018-05-01

Base courses with mineral-cement-emulsion mixes (MCEM) have been the subject of research, surveys and development of e.g. new requirements included in the Guidelines of 2014 [15]. In this paper the results of sample test and survey of road sections, assessment of transverse cracks and load-bearing capacity with FWD after 13 years of exploitation are presented. On the MCEM samples the following tests were carried out: resilient modulus using NAT, complex stiffness modulus (E*), phase shift angle at various temperatures and loading frequencies thereby obtaining master curves, fatigue life and low-temperature resistance by identifying the tensile stress restrained (TSRST) which allowed for general assessment of constructed base courses.

Evaluation of Fatigue Life of CRM-Reinforced SMA and Its Relationship to Dynamic Stiffness

PubMed Central

Mashaan, Nuha Salim; Karim, Mohamed Rehan; Abdel Aziz, Mahrez; Ibrahim, Mohd Rasdan; Katman, Herda Yati

2014-01-01

Fatigue cracking is an essential problem of asphalt concrete that contributes to pavement damage. Although stone matrix asphalt (SMA) has significantly provided resistance to rutting failure, its resistance to fatigue failure is yet to be fully addressed. The aim of this study is to evaluate the effect of crumb rubber modifier (CRM) on stiffness and fatigue properties of SMA mixtures at optimum binder content, using four different modification levels, namely, 6%, 8%, 10%, and 12% CRM by weight of the bitumen. The testing undertaken on the asphalt mix comprises the dynamic stiffness (indirect tensile test), dynamic creep (repeated load creep), and fatigue test (indirect tensile fatigue test) at temperature of 25°C. The indirect tensile fatigue test was conducted at three different stress levels (200, 300, and 400 kPa). Experimental results indicate that CRM-reinforced SMA mixtures exhibit significantly higher fatigue life compared to the mixtures without CRM. Further, higher correlation coefficient was obtained between the fatigue life and resilient modulus as compared to permanent strain; thus resilient modulus might be a more reliable indicator in evaluating the fatigue life of asphalt mixture. PMID:25050406

Blast furnace dust and phosphorous slag, new materials for use in road engineering

NASA Astrophysics Data System (ADS)

Ochoa Díaz, R.

2017-12-01

This article proposes an alternative to the use of phosphorus slag and blast furnace dust, by-products of the steel industry, due to the negative environmental impact caused by its accumulation. Taking into account the above, the pertinence of the use of these by-products in asphalt mixtures for the construction of roads is studied. In this way, the origin and its properties are presented, as well as their physical and chemical characteristics. Once the tests have been carried out, it is determined that these by-products have adequate characteristics for their use since they do not present toxicity problems. Following this, the design of the mixtures is carried out to determine the mechanical and dynamic properties and thus determine the proportion to be replaced with the conventional materials. Taking into account the results it is concluded that its use is feasible since the mixture with these by-products presents acceptable resilient modulus parameters and improvement in some verification parameters.

Performance of warm mix asphalt with Buton natural asphalt-rubber and zeolite as an additives

NASA Astrophysics Data System (ADS)

Wahjuningsih, N.; Hadiwardoyo, S. P.; Sumabrata, R. J.; Anis, M.

2018-01-01

The aim of this research is improving of asphalt industry to decrease the fuel consumption by lowering the temperature of mixing and compacting of asphalt mixture. This technology known as Warm Mix Asphalt (WMA). Buton Natural Asphalt Rubber (BNA-R) as a function of the additive has been able to improve the performance of HMA. Zeolit has a function as an additive to lowering the mixing temperature. Aggregate composition using the composition of aggregate grading specifications for airport pavement, with the composition of BNA-R 5% and 10% and Zeolite content of 2%. The mixture have produced Resilient Modulus value by using the Universal Material Testing Apparatus (UMATTA) on optimum bitumen content each of which has been obtained from the Marshall test. Furthermore, the value of permanent deformation of asphalt mixtures tested using Wheel Tracking Machine (WTM). The result shows that BNA-R modified binder for WMA can decrease the rutting potential. The additive of local materials has improved the performance of the WMA for airport pavement with certain restrictions. From this research it is known there have been changes in the characteristics of resilient modulus and permanent deformation due to the addition of BNA-R for type of aggregate composition.

Tunable mechanical stability and deformation response of a resilin-based elastomer.

PubMed

Li, Linqing; Teller, Sean; Clifton, Rodney J; Jia, Xinqiao; Kiick, Kristi L

2011-06-13

Resilin, the highly elastomeric protein found in specialized compartments of most arthropods, possesses superior resilience and excellent high-frequency responsiveness. Enabled by biosynthetic strategies, we have designed and produced a modular, recombinant resilin-like polypeptide bearing both mechanically active and biologically active domains to create novel biomaterial microenvironments for engineering mechanically active tissues such as blood vessels, cardiovascular tissues, and vocal folds. Preliminary studies revealed that these recombinant materials exhibit promising mechanical properties and support the adhesion of NIH 3T3 fibroblasts. In this Article, we detail the characterization of the dynamic mechanical properties of these materials, as assessed via dynamic oscillatory shear rheology at various protein concentrations and cross-linking ratios. Simply by varying the polypeptide concentration and cross-linker ratios, the storage modulus G' can be easily tuned within the range of 500 Pa to 10 kPa. Strain-stress cycles and resilience measurements were probed via standard tensile testing methods and indicated the excellent resilience (>90%) of these materials, even when the mechanically active domains are intercepted by nonmechanically active biological cassettes. Further evaluation, at high frequencies, of the mechanical properties of these materials were assessed by a custom-designed torsional wave apparatus (TWA) at frequencies close to human phonation, indicating elastic modulus values from 200 to 2500 Pa, which is within the range of experimental data collected on excised porcine and human vocal fold tissues. The results validate the outstanding mechanical properties of the engineered materials, which are highly comparable to the mechanical properties of targeted vocal fold tissues. The ease of production of these biologically active materials, coupled to their outstanding mechanical properties over a range of compositions, suggests their potential in tissue regeneration applications.

Characterization of solid particle erosion resistance of ductile metals based on their properties

NASA Technical Reports Server (NTRS)

Rao, P. V.; Buckley, D. H.

1985-01-01

This paper presents experimental results pertaining to spherical glass bead and angular crushed glass particle impingement. A concept of energy absorption to explain the failure of material is proposed and is correlated with the erosion characteristics of several pure metals. Analyses of extensive erosion data indicate that the properties - surface energy, specific melting energy, strain energy, melting point, bulk modulus, hardness, atomic volume - and the product of the parameters - linear coefficient of thermal expansion x bulk modulus x temperature rise required for melting, and ultimate resilience x hardness - exhibit the best correlations. The properties of surface energy and atomic volume are suggested for the first time for correlation purposes and are found to correlate well with erosion rates at different angles of impingement. It further appears that both energy and thermal properties contribute to the total erosion.

Criteria for the Use of Lime-Cement-Flyash on Airport Pavements

DTIC Science & Technology

1989-12-01

conducted in which core sarples were obtained from Newark, Portland, and JFK airports . The samples were tested for modulus of resilience and unconfined...Port Authority of New York and New Jersey to finalize the plans for core removal at Newark and JFK Airports . At the meeting, it was agreed that cores...would be extracted at JFK Airport later that month. Similarly, core extractions would begin at Newark Airport the next day after campletion of the JFK

Effect of various filler types on the properties of porous asphalt mixture

NASA Astrophysics Data System (ADS)

Shukry, Nurul Athma Mohd; Hassan, Norhidayah Abdul; Ezree Abdullah, Mohd; Rosli Hainin, Mohd; Yusoff, Nur Izzi Md; Putra Jaya, Ramadhansyah; Mohamed, Azman

2018-04-01

The open structure of porous asphalt exposes a large surface area to the effects of air and water, which accelerates the oxidation rate and affects the coating properties of the binder. These factors may influence the adhesive strength of the binder-aggregate and lead to cohesive failure within the binder film, contributing to aggregate stripping and moisture damage. The addition of fillers in asphalt mixtures has been identified to stiffen the asphalt binder and improve mixture strength. This study investigates the effect of various filler types (hydrated lime, cement, and diatomite) on the properties of porous asphalt. Compacted samples of porous asphalt were prepared using Superpave gyratory compactor at the target air void content of 21%. Each sample was incorporated with 2% of filler and polymer-modified binder of PG76. The morphology and chemical composition of fillers were investigated with a field emission scanning electron microscope (FESEM) and energy dispersive X-ray (EDX) analysis. The properties of porous asphalt were evaluated in terms of permeability, abrasion loss, resilient modulus, and indirect tensile strength. All mixtures were found to show high permeability rates. Mixtures with hydrated lime exhibited lower abrasion loss compared to mixtures with cement and diatomite. The use of diatomite increases the resistance of the mixtures to rutting and moisture damage compared to other fillers as shown by the enhanced resilient modulus and indirect tensile strength.

Method for resonant measurement

DOEpatents

Rhodes, George W.; Migliori, Albert; Dixon, Raymond D.

1996-01-01

A method of measurement of objects to determine object flaws, Poisson's ratio (.sigma.) and shear modulus (.mu.) is shown and described. First, the frequency for expected degenerate responses is determined for one or more input frequencies and then splitting of degenerate resonant modes are observed to identify the presence of flaws in the object. Poisson's ratio and the shear modulus can be determined by identification of resonances dependent only on the shear modulus, and then using that shear modulus to find Poisson's ratio using other modes dependent on both the shear modulus and Poisson's ratio.

Assessment of Characteristic Function Modulus of Vibroacoustic Signal Given a Limit State Parameter of Diagnosed Equipment

NASA Astrophysics Data System (ADS)

Kostyukov, V. N.; Naumenko, A. P.; Kudryavtseva, I. S.

2018-01-01

Improvement of distinguishing criteria, determining defects of machinery and mechanisms, by vibroacoustic signals is a recent problem for technical diagnostics. The work objective is assessment of instantaneous values by methods of statistical decision making theory and risk of regulatory values of characteristic function modulus. The modulus of the characteristic function is determined given a fixed parameter of the characteristic function. It is possible to determine the limits of the modulus, which correspond to different machine’s condition. The data of the modulus values are used as diagnostic features in the vibration diagnostics and monitoring systems. Using such static decision-making methods as: minimum number of wrong decisions, maximum likelihood, minimax, Neumann-Pearson characteristic function modulus limits are determined, separating conditions of a diagnosed object.

Method for resonant measurement

DOEpatents

Rhodes, G.W.; Migliori, A.; Dixon, R.D.

1996-03-05

A method of measurement of objects to determine object flaws, Poisson`s ratio ({sigma}) and shear modulus ({mu}) is shown and described. First, the frequency for expected degenerate responses is determined for one or more input frequencies and then splitting of degenerate resonant modes are observed to identify the presence of flaws in the object. Poisson`s ratio and the shear modulus can be determined by identification of resonances dependent only on the shear modulus, and then using that shear modulus to find Poisson`s ratio using other modes dependent on both the shear modulus and Poisson`s ratio. 1 fig.

Expression, crosslinking, and developing modulus master curves of recombinant resilin.

PubMed

Khandaker, Md Shahriar K; Dudek, Daniel M; Beers, Eric P; Dillard, David A

2017-05-01

Resilin is a disordered elastomeric protein found in specialized regions of insect cuticles, where low stiffness and high resilience are required. Having a wide range of functions that vary among insect species, resilin operates across a wide frequency range, from 5Hz for locomotion to 13kHz for sound production. We synthesize and crosslink a recombinant resilin from clone-1 (exon-1+exon-2) of the gene, and determine the water content (approximately 80wt%) and dynamic mechanical properties, along with estimating surface energies relevant for adhesion. Dynamic moduli master curves have been developed, by applying the time-temperature superposition principle (TTSP) and time-temperature concentration superposition principle (TTCSP), and compared with reported master curves for natural resilin from locusts, dragonflies, and cockroaches. To our knowledge, this is the first time dynamic moduli master curves have been developed to explore the dynamic mechanical properties of recombinant resilin and compare with resilin behavior. The resulting master curves show that the synthetic resilin undergoes a pronounced transition with increasing ethanol concentrations, with the storage modulus increasing by approximately three orders of magnitude. Although possibly a glass transition, alternate explanations include the formation of intramolecular hydrogen bonds or that the chitin binding domain (ChBD) in exon-2 might change the secondary structure of the normally disordered exon-1 into more ordered conformations that limit deformation. Copyright © 2017 Elsevier Ltd. All rights reserved.

Architecturally defined scaffolds from synthetic collagen and elastin analogues for the fabrication of bioengineered tissues

NASA Astrophysics Data System (ADS)

Caves, Jeffrey Morris

The microstructure and mechanics of collagen and elastin protein fiber networks dictate the mechanical responses of all soft tissues and related organ systems. In this project, we endeavored to meet or exceed native tissue biomechanical properties through mimicry of these extracellular matrix components with synthetic collagen fiber and a recombinant elastin-like protein polymer. Significantly, this work led to the development of a framework for the design and fabrication of protein-based tissue substitutes with enhanced strength, resilience, anisotropy, and more. We began with the development of a spinning process for scalable production of synthetic collagen fiber. Fiber with an elliptical cross-section of 53 +/- 14 by 21 +/- 3 mum and an ultimate tensile strength of 90 +/- 19 MPa was continuously produced at 60 meters per hour from an ultrafiltered collagen solution. The starting collagen concentration, flowrate, and needle size could be adjusted to control fiber size. The fiber was characterized with mechanical analysis, micro-differential scanning calorimetry, transmission electron microscopy, second harmonic generation analysis, and subcutaneous murine implant. We subsequently describe the scalable, semi-automated fabrication of elastin-like protein sheets reinforced with synthetic collagen fibers that can be positioned in a precisely defined three-dimensional hierarchical pattern. Multilamellar, fiber-reinforced elastic protein sheets were constructed with controlled fiber orientation and volume fraction. Structures were analyzed with scanning electron microscopy, transmission electron microscopy, and digital volumetric imaging. The effect of fiber orientation and volume fraction on Young's Modulus, yield stress, ultimate tensile stress, strain-to-failure, and resilience was evaluated in uniaxial tension. Increased fiber volume fraction and alignment with applied deformation significantly increased Young's Modulus, resilience, and yield stress. Highly extensible, elastic tissues display a functionally important mechanical transition from low to high modulus deformation at a strain dictated by the crimped microstructure of native collagen fiber. We report the fabrication of dense arrays of microcrimped synthetic collagen fiber embedded in elastin-like protein lamellae that mimic this aspect of tissue mechanics. Microcrimped fiber arrays were characterized with scanning electron microscopy, confocal laser scanning microscopy, and uniaxial tension analysis. Crimp wavelength was 143 +/- 5 mum. The degree of crimping was varied from 3.1% to 9.4%, and corresponded to mechanical modulus transitions at 4.6% and 13.3% strain. Up to 1000 cycles of tensile loading did not substantially alter microcrimp morphology. We designed and prototyped a series of small-diameter vascular grafts consisting of elastin-like protein reinforced with controlled volume fractions and orientations of collagen fiber. A pressure-diameter system was developed and implemented to study the effects of fiber distribution on graft mechanics. The optimal design satisfied target properties with suture retention strength of 173 +/- 4 g-f, burst strength of 1483 +/- 143 mm Hg, and compliance of 5.1 +/- 0.8 %/100 mm Hg.

Modulus and yield stress of drawn LDPE

NASA Astrophysics Data System (ADS)

Thavarungkul, Nandh

Modulus and yield stress were investigated in drawn low density polyethylene (LDPE) film. Uniaxially drawn polymeric films usually show high values of modulus and yield stress, however, studies have normally only been conducted to identify the structural features that determine modulus. In this study small-angle x-ray scattering (SAXS), thermal shrinkage, birefringence, differential scanning calorimetry (DSC), and dynamic mechanical thermal analysis (DMTA) were used to examine, directly and indirectly, the structural features that determine both modulus and yield stress, which are often closely related in undrawn materials. Shish-kebab structures are proposed to account for the mechanical properties in drawn LDPE. The validity of this molecular/morphological model was tested using relationships between static mechanical data and structural and physical parameters. In addition, dynamic mechanical results are also in line with static data in supporting the model. In the machine direction (MD), "shish" and taut tie molecules (TTM) anchored in the crystalline phase account for E; whereas crystal lamellae with contributions from "shish" and TTM determine yield stress. In the transverse direction (TD), the crystalline phase plays an important roll in both modulus and yield stress. Modulus is determined by crystal lamellae functioning as platelet reinforcing elements in the amorphous matrix with an additional contributions from TTM and yield stress is determined by the crystal lamellae's resistance to deformation.

Determination of elastic modulus of ceramics using ultrasonic testing

NASA Astrophysics Data System (ADS)

Sasmita, Firmansyah; Wibisono, Gatot; Judawisastra, Hermawan; Priambodo, Toni Agung

2018-04-01

Elastic modulus is important material property on structural ceramics application. However, bending test as a common method for determining this property require particular specimen preparation. Furthermore, elastic modulus of ceramics could vary because it depends on porosity content. For structural ceramics industry, such as ceramic tiles, this property is very important. This drives the development of new method to improve effectivity or verification method as well. In this research, ultrasonic testing was conducted to determine elastic modulus of soda lime glass and ceramic tiles. The experiment parameter was frequency of probe (1, 2, 4 MHz). Characterization of density and porosity were also done for analysis. Results from ultrasonic testing were compared with elastic modulus resulted from bending test. Elastic modulus of soda-lime glass based on ultrasonic testing showed excellent result with error 2.69% for 2 MHz probe relative to bending test result. Testing on red and white ceramic tiles were still contained error up to 41% and 158%, respectively. The results for red ceramic tile showed trend that 1 MHz probe gave better accuracy in determining elastic modulus. However, testing on white ceramic tile showed different trend. It was due to the presence of porosity and near field effect.

Dynamic rheology of food protein networks

USDA-ARS?s Scientific Manuscript database

Small amplitude oscillatory shear analyses of samples containing protein are useful for determining the nature of the protein matrix without damaging it. Elastic modulus, viscous modulus, and loss tangent (the ratio of viscous modulus to elastic modulus) give information on the strength of the netw...

Biomimetic poly(lactide) based fibrous scaffolds for ligament tissue engineering.

PubMed

Surrao, Denver C; Waldman, Stephen D; Amsden, Brian G

2012-11-01

The aim of this study was to fabricate a fibrous scaffold that closely resembled the micro-structural architecture and mechanical properties of collagen fibres found in the anterior cruciate ligament (ACL). To achieve this aim, fibrous scaffolds were made by electrospinning L-lactide based polymers. L-Lactide was chosen primarily due to its demonstrated biocompatibility, biodegradability and high modulus. The electrospun fibres were collected in tension on a rotating wire mandrel. Upon treating these fibres in a heated aqueous environment, they possessed a crimp-like pattern having a wavelength and amplitude similar to that of native ACL collagen. Of the polymer fibre scaffolds studied, those made from poly(L-lactide-co-D,L-lactide) PLDLA exhibited the highest modulus and were also the most resilient to in vitro hydrolytic degradation, undergoing a slight decrease in modulus compared to the other polymeric fibres over a 6 month period. Bovine fibroblasts seeded on the wavy, crimp-like PLDLA fibres attached, proliferated and deposited extracellular matrix (ECM) molecules on the surface of the fibrous scaffold. In addition, the deposited ECM exhibited bundle formation that resembled the fascicles found in native ACL. These findings demonstrate the importance of replicating the geometric microenvironment in developing effective tissue engineering scaffolds. Copyright © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Size dependent elastic modulus and mechanical resilience of dental enamel.

PubMed

O'Brien, Simona; Shaw, Jeremy; Zhao, Xiaoli; Abbott, Paul V; Munroe, Paul; Xu, Jiang; Habibi, Daryoush; Xie, Zonghan

2014-03-21

Human tooth enamel exhibits a unique microstructure able to sustain repeated mechanical loading during dental function. Although notable advances have been made towards understanding the mechanical characteristics of enamel, challenges remain in the testing and interpretation of its mechanical properties. For example, enamel was often tested under dry conditions, significantly different from its native environment. In addition, constant load, rather than indentation depth, has been used when mapping the mechanical properties of enamel. In this work, tooth specimens are prepared under hydrated conditions and their stiffnesses are measured by depth control across the thickness of enamel. Crystal arrangement is postulated, among other factors, to be responsible for the size dependent indentation modulus of enamel. Supported by a simple structure model, effective crystal orientation angle is calculated and found to facilitate shear sliding in enamel under mechanical contact. In doing so, the stress build-up is eased and structural integrity is maintained. Copyright © 2014 Elsevier Ltd. All rights reserved.

A simple model for enamel fracture from margin cracks.

PubMed

Chai, Herzl; Lee, James J-W; Kwon, Jae-Young; Lucas, Peter W; Lawn, Brian R

2009-06-01

We present results of in situ fracture tests on extracted human molar teeth showing failure by margin cracking. The teeth are mounted into an epoxy base and loaded with a rod indenter capped with a Teflon insert, as representative of food modulus. In situ observations of cracks extending longitudinally upward from the cervical margins are recorded in real time with a video camera. The cracks appear above some threshold and grow steadily within the enamel coat toward the occlusal surface in a configuration reminiscent of channel-like cracks in brittle films. Substantially higher loading is required to delaminate the enamel from the dentin, attesting to the resilience of the tooth structure. A simplistic fracture mechanics analysis is applied to determine the critical load relation for traversal of the margin crack along the full length of the side wall. The capacity of any given tooth to resist failure by margin cracking is predicted to increase with greater enamel thickness and cuspal radius. Implications in relation to dentistry and evolutionary biology are briefly considered.

Determination of resilient properties of unbound materials with repeated load triaxial and diametral test systems.

DOT National Transportation Integrated Search

1981-12-01

Repeated load diametral test systems are experiencing increased use to determine resilient properties of asphalt concrete and admixture stabilized materials; they have not been used extensively to determine the resilient properties of unbound materia...

Computational modeling of the effective Young's modulus values of fullerene molecules: a combined molecular dynamics simulation and continuum shell model.

PubMed

Ghavanloo, Esmaeal; Izadi, Razie; Nayebi, Ali

2018-02-28

Estimating the Young's modulus of a structure in the nanometer size range is a difficult task. The reliable determination of this parameter is, however, important in both basic and applied research. In this study, by combining molecular dynamics (MD) simulations and continuum shell theory, we designed a new approach to determining the Young's modulus values of different spherical fullerenes. The results indicate that the Young's modulus values of fullerene molecules decrease nonlinearly with increasing molecule size and understandably tend to the Young's modulus of an ideal flat graphene sheet at large molecular radii. To the best of our knowledge, this is first time that a combined atomistic-continuum method which can predict the Young's modulus values of fullerene molecules with high precision has been reported.

Resilience of caregivers of people with dementia: a systematic review of biological and psychosocial determinants.

PubMed

Dias, Rachel; Santos, Raquel Luiza; Sousa, Maria Fernanda Barroso de; Nogueira, Marcela Moreira Lima; Torres, Bianca; Belfort, Tatiana; Dourado, Marcia Cristina Nascimento

2015-01-01

Although caregivers of people with dementia may face difficulties, some positive feelings of caregiving may be associated with resilience. This study systematically reviewed the definitions, methodological approaches and determinant models associated with resilience among caregivers of people with dementia. Search for articles published between 2003 and 2014 in ISI, PubMed/MEDLINE, SciELO and Lilacs using the search terms resilience, caregivers and dementia. Resilience has been defined as positive adaptation to face adversity, flexibility, psychological well-being, strength, healthy life, burden, social network and satisfaction with social support. No consensus was found about the definition of resilience associated with dementia. We classified the determinant variables into biological, psychological and social models. Higher levels of resilience were associated with lower depression rates and greater physical health. Other biological factors associated with higher levels of resilience were older age, African-American ethnicity and female sex. Lower burden, stress, neuroticism and perceived control were the main psychological factors associated with resilience. Social support was a moderating factor of resilience, and different types of support seemed to relieve the physical and mental overload caused by stress.

Determination of the Mechanical Properties of Plasma-Sprayed Hydroxyapatite Coatings Using the Knoop Indentation Technique

NASA Astrophysics Data System (ADS)

Hasan, Md. Fahad; Wang, James; Berndt, Christopher

2015-06-01

The microhardness and elastic modulus of plasma-sprayed hydroxyapatite coatings were evaluated using Knoop indentation on the cross section and on the top surface. The effects of indentation angle, testing direction, measurement location and applied load on the microhardness and elastic modulus were investigated. The variability and distribution of the microhardness and elastic modulus data were statistically analysed using the Weibull modulus distribution. The results indicate that the dependence of microhardness and elastic modulus on the indentation angle exhibits a parabolic shape. Dependence of the microhardness values on the indentation angle follows Pythagoras's theorem. The microhardness, Weibull modulus of microhardness and Weibull modulus of elastic modulus reach their maximum at the central position (175 µm) on the cross section of the coatings. The Weibull modulus of microhardness revealed similar values throughout the thickness, and the Weibull modulus of elastic modulus shows higher values on the top surface compared to the cross section.

Risk Factors as Major Determinants of Resilience: A Replication Study.

PubMed

Eshel, Yohanan; Kimhi, Shaul; Lahad, Mooli; Leykin, Dmitry; Goroshit, Marina

2018-03-16

The present study was conducted in the context of current concerns about replication in psychological research. It claims that risk factors should be regarded as an integral part of the definition of individual resilience, which should be defined in terms of the balance between individual strength or protective factors, and individual vulnerability or risk factors (IND-SVR). Five independent samples, including 3457 Israeli participants, were employed to determine the effects of resilience promoting and resilience suppressing variables on the IND-SVR index of resilience, and on its two components: recovery from adversity, and distress symptoms. Five path analyses were employed for determining the role of distress symptoms as a measure of psychological resilience, as compared to other indices of this resilience. Results indicated the major role of risk factors (distress symptoms) as an integral component of resilience. This role was generally replicated in the five investigated samples. Risk factors are legitimate, valid, and useful parts of the definition of psychological resilience. Resilience research has shifted away from studying individual risk factors to investigating the process through which individuals overcome the hardships they experience. The present data seem to suggest that this shift should be reexamined.

Resilience definitions, theory, and challenges: interdisciplinary perspectives.

PubMed

Southwick, Steven M; Bonanno, George A; Masten, Ann S; Panter-Brick, Catherine; Yehuda, Rachel

2014-01-01

In this paper, inspired by the plenary panel at the 2013 meeting of the International Society for Traumatic Stress Studies, Dr. Steven Southwick (chair) and multidisciplinary panelists Drs. George Bonanno, Ann Masten, Catherine Panter-Brick, and Rachel Yehuda tackle some of the most pressing current questions in the field of resilience research including: (1) how do we define resilience, (2) what are the most important determinants of resilience, (3) how are new technologies informing the science of resilience, and (4) what are the most effective ways to enhance resilience? These multidisciplinary experts provide insight into these difficult questions, and although each of the panelists had a slightly different definition of resilience, most of the proposed definitions included a concept of healthy, adaptive, or integrated positive functioning over the passage of time in the aftermath of adversity. The panelists agreed that resilience is a complex construct and it may be defined differently in the context of individuals, families, organizations, societies, and cultures. With regard to the determinants of resilience, there was a consensus that the empirical study of this construct needs to be approached from a multiple level of analysis perspective that includes genetic, epigenetic, developmental, demographic, cultural, economic, and social variables. The empirical study of determinates of resilience will inform efforts made at fostering resilience, with the recognition that resilience may be enhanced on numerous levels (e.g., individual, family, community, culture).

Resilience definitions, theory, and challenges: interdisciplinary perspectives

PubMed Central

Southwick, Steven M.; Bonanno, George A.; Masten, Ann S.; Panter-Brick, Catherine; Yehuda, Rachel

2014-01-01

In this paper, inspired by the plenary panel at the 2013 meeting of the International Society for Traumatic Stress Studies, Dr. Steven Southwick (chair) and multidisciplinary panelists Drs. George Bonanno, Ann Masten, Catherine Panter-Brick, and Rachel Yehuda tackle some of the most pressing current questions in the field of resilience research including: (1) how do we define resilience, (2) what are the most important determinants of resilience, (3) how are new technologies informing the science of resilience, and (4) what are the most effective ways to enhance resilience? These multidisciplinary experts provide insight into these difficult questions, and although each of the panelists had a slightly different definition of resilience, most of the proposed definitions included a concept of healthy, adaptive, or integrated positive functioning over the passage of time in the aftermath of adversity. The panelists agreed that resilience is a complex construct and it may be defined differently in the context of individuals, families, organizations, societies, and cultures. With regard to the determinants of resilience, there was a consensus that the empirical study of this construct needs to be approached from a multiple level of analysis perspective that includes genetic, epigenetic, developmental, demographic, cultural, economic, and social variables. The empirical study of determinates of resilience will inform efforts made at fostering resilience, with the recognition that resilience may be enhanced on numerous levels (e.g., individual, family, community, culture). PMID:25317257

A Whole Community Approach toward Child and Youth Resilience Promotion: A Review of Resilience Literature.

PubMed

Khanlou, Nazilla; Wray, Ron

2014-01-01

A literature review of child and youth resilience with a focus on: definitions and factors of resilience; relationships between resilience, mental health and social outcomes; evidence for resilience promoting interventions; and implications for reducing health inequities. To conduct the review, the first two following steps were conducted iteratively and informed the third step: 1) Review of published peer-review literature since 2000; and 2) Review of grey literature; and 3) Quasi-realist synthesis of evidence. Evidence from three perspectives were examined: i) whether interventions can improve 'resilience' for vulnerable children and youth; ii) whether there is a differential effect among different populations; and, iii) whether there is evidence that resilience interventions 'close the gap' on health and social outcome measures. Definitions of resilience vary as do perspectives on it. We argue for a hybrid approach that recognizes the value of combining multiple theoretical perspectives, epistemologies (positivistic and constructivist/interpretive/critical) in studying resilience. Resilience is: a) a process (rather than a single event), b) a continuum (rather than a binary outcome), and c) likely a global concept with specific dimensions. Individual, family and social environmental factors influence resilience. A social determinants perspective on resilience and mental health is emphasized. Programs and interventions to promoting resilience should be complimentary to public health measures addressing the social determinants of health. A whole community approach to resilience is suggested as a step toward closing the public health policy gap. Local initiatives that stimulate a local transformation process are needed. Recognition of each child's or youth's intersections of gender, lifestage, family resources within the context of their identity markers fits with a localized approach to resilience promotion and, at the same time, requires recognition of the broader determinants of population health.

Apparent elastic modulus and hysteresis of skeletal muscle cells throughout differentiation

NASA Technical Reports Server (NTRS)

Collinsworth, Amy M.; Zhang, Sarah; Kraus, William E.; Truskey, George A.

2002-01-01

The effect of differentiation on the transverse mechanical properties of mammalian myocytes was determined by using atomic force microscopy. The apparent elastic modulus increased from 11.5 +/- 1.3 kPa for undifferentiated myoblasts to 45.3 +/- 4.0 kPa after 8 days of differentiation (P < 0.05). The relative contribution of viscosity, as determined from the normalized hysteresis area, ranged from 0.13 +/- 0.02 to 0.21 +/- 0.03 and did not change throughout differentiation. Myosin expression correlated with the apparent elastic modulus, but neither myosin nor beta-tubulin were associated with hysteresis. Microtubules did not affect mechanical properties because treatment with colchicine did not alter the apparent elastic modulus or hysteresis. Treatment with cytochalasin D or 2,3-butanedione 2-monoxime led to a significant reduction in the apparent elastic modulus but no change in hysteresis. In summary, skeletal muscle cells exhibited viscoelastic behavior that changed during differentiation, yielding an increase in the transverse elastic modulus. Major contributors to changes in the transverse elastic modulus during differentiation were actin and myosin.

Resilience in Elders of the Sardinian Blue Zone: An Explorative Study.

PubMed

Fastame, Maria Chiara; Hitchcott, Paul Kenneth; Mulas, Ilaria; Ruiu, Marilena; Penna, Maria Pietronilla

2018-02-26

Background : older adults from the Sardinian Blue Zone self-report low depressive symptoms and high psychological well-being. However, the role of dispositional resilience as a determinant of these characteristics is unknown. Objectives : the current study had three aims. First, to investigate associations among several putative predictors, including dispositional resilience and three established markers of positive and negative mental health. Second, to determine if gender differences in dispositional resilience, independent of age and cognitive impairment, are present in this population. Third, to examine the relative importance of the predictors of self-reported mental health and well-being. Methods : 160 elders were recruited in the Sardinian Blue Zone. The participants completed self-report measures of dispositional resilience, satisfaction with social ties, physical health, depressive symptoms, and psychological well-being. Results : trait resilience was significantly associated with predictors and markers of mental health. Males had significantly greater trait resilience. In regression analyses, dispositional resilience and satisfaction with social ties were significant predictors of all markers of mental health. Other factors were significantly associated only with certain markers. Conclusions : trait resilience and strong social ties appear to be key determinants of the high mental health of Sardinian Blue Zone older adults.

Ulysses' Return: Resilient Male Leaders Still at the Helm

ERIC Educational Resources Information Center

McClellan, Rhonda; Christman, Dana; Fairbanks, Anthony

2008-01-01

This study examined resilient men in higher education administration, educational leadership programs to determine how they identified components of their resiliency, how they described events that demonstrated their resiliency, and how they prescribed ways in which preparation programs can foster resiliency in students. Using masculinity…

Adhesive and Cohesive Strength in FeB/Fe2B Systems

NASA Astrophysics Data System (ADS)

Meneses-Amador, A.; Blancas-Pérez, D.; Corpus-Mejía, R.; Rodríguez-Castro, G. A.; Martínez-Trinidad, J.; Jiménez-Tinoco, L. F.

2018-05-01

In this work, FeB/Fe2B systems were evaluated by the scratch test. The powder-pack boriding process was performed on the surface of AISI M2 steel. The mechanical parameters, such as yield stress and Young's modulus of the boride layer, were obtained by the instrumented indentation technique. Residual stresses produced on the boride layer were estimated by using the x-ray diffraction (XRD) technique. The scratch test was performed in order to evaluate the cohesive/adhesive strength of the FeB/Fe2B coating. In addition, a numerical evaluation of the scratch test on boride layers was performed by the finite element method. Maximum principal stresses were related to the failure mechanisms observed by the experimental scratch test. Shear stresses at the interfaces of the FeB/Fe2B/substrate system were also evaluated. Finally, the results obtained provide essential information about the effect of the layer thickness, the residual stresses, and the resilience modulus on the cohesive/adhesive strength in FeB/Fe2B systems.

Elastic modulus of phases in Ti–Mo alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Wei-dong; Liu, Yong, E-mail: yonliu11@aliyun.com; Wu, Hong

2015-08-15

In this work, a series of binary Ti–Mo alloys with the Mo contents ranging from 3.2 to 12 at.% were prepared using non-consumable arc melting. The microstructures were investigated by X-ray diffraction and transmission electron microscope, and the elastic modulus was evaluated by nanoindentation testing technique. The evolution of the volume fractions of ω phase was investigated using X-ray photoelectron spectroscopy. The results indicated that the phase constitution and elastic modulus of the Ti–Mo alloys are sensitive to the Mo content. Ti–3.2Mo and Ti–8Mo alloys containing only α and β phases, respectively, have a low elastic modulus. In contrast, Ti–4.5Mo,more » Ti–6Mo, Ti–7Mo alloys, with different contents of ω phase, have a high elastic modulus. A simple micromechanical model was used to calculate the elastic modulus of ω phase (E{sub ω}), which was determined to be 174.354 GPa. - Highlights: • Ti–Mo alloys with the Mo contents ranging from 3.2 to 12 at.% were investigated. • XPS was used to investigate the volume fractions of ω phase. • The elastic modulus of Ti–Mo alloys is sensitive to the Mo content. • The elastic modulus of ω phase was determined to be 174.354 GPa.« less

Use of an ultrasonic device for the determination of elastic modulus of dentin.

PubMed

Miyazaki, Masashi; Inage, Hirohiko; Onose, Hideo

2002-03-01

The mechanical properties of dentin substrate are one of the important factors in determining bond strength of dentin bonding systems. The purpose of this study was to determine the elastic modulus of dentin substrate with the use of an ultrasonic device. The dentin disks of about 1 mm thickness were obtaining from freshly extracted human third molars, and the dentin disk was shaped in a rectangular form with a line diamond point. The size and weight of each specimen was measured to calculate the density of the specimen. The ultrasonic equipment employed in this study was composed of a Pulser-Receiver (Model 5900PR, Panametrics), transducers (V155, V156, Panametrics) and an oscilloscope. The measured two-way transit time through the dentin disk was divided by two to account for the down-and-back travel path, and then multiplied by the velocity of sound in the test material. Measuring the longitudinal and share wave sound velocity determine elastic modulus. The mean elastic modulus of horizontally sectioned specimens was 21.8 GPa and 18.5 GPa for the vertically sectioned specimens, and a significant difference was found between the two groups. The ultrasonic method used in this study shows considerable promise for determination of the elastic modulus of the tooth substrate.

Elastic modulus of single cellulose microfibrils from tunicate measured by atomic force microscopy.

PubMed

Iwamoto, Shinichiro; Kai, Weihua; Isogai, Akira; Iwata, Tadahisa

2009-09-14

The elastic modulus of single microfibrils from tunicate ( Halocynthia papillosa ) cellulose was measured by atomic force microscopy (AFM). Microfibrils with cross-sectional dimensions 8 x 20 nm and several micrometers in length were obtained by oxidation of cellulose with 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO) as a catalyst and subsequent mechanical disintegration in water and by sulfuric acid hydrolysis. The nanocellulosic materials were deposited on a specially designed silicon wafer with grooves 227 nm in width, and a three-point bending test was applied to determine the elastic modulus using an AFM cantilever. The elastic moduli of single microfibrils prepared by TEMPO-oxidation and acid hydrolysis were 145.2 +/- 31.3 and 150.7 +/- 28.8 GPa, respectively. The result showed that the experimentally determined modulus of the highly crystalline tunicate microfibrils was in agreement with the elastic modulus of native cellulose crystals.

Elastic modulus of nanomaterials: resonant contact-AFM measurement and reduced-size effects (Invited Paper)

NASA Astrophysics Data System (ADS)

Nysten, Bernard; Fretigny, Christian; Cuenot, Stephane

2005-05-01

Resonant contact atomic force microscopy (resonant C-AFM) is used to quantitatively measure the elastic modulus of polymer nanotubes and metallic nanowires. To achieve this, an oscillating electric field is applied between the sample holder and the microscope head to excite the oscillation of the cantilever in contact with the nanostructures suspended over the pores of a membrane. The resonance frequency of the cantilever with the tip in contact with a nanostructure is shifted to higher values with respect to the resonance frequency of the free cantilever. It is demonstrated that the system can simply be modeled by a cantilever with the tip in contact with two springs. The measurement of the frequency shift enables the direct determination of the spring stiffness, i.e. the nanowires or nanotube stiffness. The method also enables the determination of the boundary conditions of the nanobeam on the membrane. The tensile elastic modulus is then simply determined using the classical theory of beam deflection. The obtained results for the larger nanostructures fairly agree to the values reported in the literature for the macroscopic elastic modulus of the corresponding materials. The measured modulus of the nanomaterials with smaller diameters is significantly higher than that of the larger ones. The increase of the apparent elastic modulus for the smaller diameters is attributed to the surface tension effects. It is thus demonstrated that resonant C-AFM enables the measurement of the elastic modulus and of the surface tension of nanomaterials.

Biodegradable polyurethane ureas with variable polyester or polycarbonate soft segments: effects of crystallinity, molecular weight, and composition on mechanical properties.

PubMed

Ma, Zuwei; Hong, Yi; Nelson, Devin M; Pichamuthu, Joseph E; Leeson, Cory E; Wagner, William R

2011-09-12

Biodegradable polyurethane urea (PUU) elastomers are ideal candidates for fabricating tissue engineering scaffolds with mechanical properties akin to strong and resilient soft tissues. PUU with a crystalline poly(ε-caprolactone) (PCL) macrodiol soft segment (SS) showed good elasticity and resilience at small strains (<50%) but showed poor resilience under large strains because of stress-induced crystallization of the PCL segments, with a permanent set of 677 ± 30% after tensile failure. To obtain softer and more resilient PUUs, we used noncrystalline poly(trimethylene carbonate) (PTMC) or poly(δ-valerolactone-co-ε-caprolactone) (PVLCL) macrodiols of different molecular weights as SSs that were reacted with 1,4-diisocyanatobutane and chain extended with 1,4-diaminobutane. Mechanical properties of the PUUs were characterized by tensile testing with static or cyclic loading and dynamic mechanical analysis. All of the PUUs synthesized showed large elongations at break (800-1400%) and high tensile strength (30-60 MPa). PUUs with noncrystalline SSs all showed improved elasticity and resilience relative to the crystalline PCL-based PUU, especially for the PUUs with high molecular weight SSs (PTMC 5400 M(n) and PVLCL 6000 M(n)), of which the permanent deformation after tensile failure was only 12 ± 7 and 39 ± 4%, respectively. The SS molecular weight also influenced the tensile modulus in an inverse fashion. Accelerated degradation studies in PBS containing 100 U/mL lipase showed significantly greater mass loss for the two polyester-based PUUs versus the polycarbonate-based PUU and for PVLCL versus PCL polyester PUUs. Basic cytocompatibility was demonstrated with primary vascular smooth muscle cell culture. The synthesized families of PUUs showed variable elastomeric behavior that could be explained in terms of the underlying molecular design and crystalline behavior. Depending on the application target of interest, these materials may provide options or guidance for soft tissue scaffold development.

[Psychological well-being in nursing: relationships with resilience and coping].

PubMed

Arrogante, Óscar; Pérez-García, Ana Maria; Aparicio-Zaldívar, Eva G

2015-01-01

To determine the differences in resilience, coping, and psychological well-being (PWB) among nursing professionals of different hospital services, as well as to establish a structural model in nursing staff where resilience and coping were included. Correlational and cross-sectorial study with probabilistic sampling. A sample of 208 nursing professionals from University Hospital of Fuenlabrada (Madrid) took part in the study. This sample consisted of nurses (n = 133), nursing assistants (n = 61), and midwives (n = 14), of whom 94 worked in special units and 114 worked in wards. 10-Item CD-RISC (resilience), Brief-Cope (coping strategies), PWB scales (PWB dimensions), and sociodemographic variables. No differences were found in any assessed psychological variables as regards hospital service worked in. A structural model was found where resilience was a precursor factor of coping that determined the PWB of the nurses. Resilience favoured strategies related to engagement coping with stressful situations (β = 0.56) that contributed to PWB (β = 0.43) (these relationships were inverted in the case of disengagement coping). Resilience is an inherent feature in nursing staff whether they work in special units or wards. Coping strategies focused on engagement (or adaptive) with the stressful situation determined nursing PWB (primarily self-acceptance and environment mastery dimensions). Resilience and coping strategies more adaptives constitute two personal resources that determine PWB. Copyright © 2014 Elsevier España, S.L.U. All rights reserved.

Water Droplet Erosion Behavior of High-Power Diode Laser Treated 17Cr4Ni PH Stainless Steel

NASA Astrophysics Data System (ADS)

Mann, B. S.

2014-05-01

This article deals with water droplet erosion (WDE) behavior of high-power diode laser (HPDL) treated 17Cr4Ni PH stainless steel. After HPDL treatment, the water droplet erosion resistance (WDER) of 17Cr4Ni PH stainless steel has not improved. The main reason is the surface hardness, which has not improved after HPDL treatment though the microstructure has become much finer. On the other hand, precipitation hardening of the alloy at 490°C for 3 h has resulted in improved WDER more than twice. This is because of its increased microhardness and improved modified ultimate resilience (MUR), and formation of fine grained microstructure. The WDER has been correlated with MUR, a single mechanical property, based upon microhardness, ultimate tensile strength, and Young's modulus. WDERs of HPDL treated, untreated, and precipitation hardened 17Cr4Ni PH stainless steel samples were determined using a WDE test facility as per ASTM G73-1978. The WDE damage mechanism, compared on the basis of MUR and scanning electron micrographs, is discussed and reported in this article.

Comparison of influence of ageing on low-temperature characteristics of asphalt mixtures

NASA Astrophysics Data System (ADS)

Vacková, Pavla; Valentin, Jan; Benešová, Lucie

2017-09-01

Ability of relaxation of asphalt mixtures and thus its resilience to climate change and traffic load is decreasing by influence of aging - in this case aging of bituminous binder. Binder exposed to climate and UV ages and becomes more fragile and susceptible to damage. The results of the research presented in this paper are aimed to finding a correlation between low-temperature properties of referential and aged asphalt mixture specimens and characteristics (not low-temperature) of bituminous binders. In this research there were used conventional road binders, commonly used modified binders and binders additionally modified in the laboratory. The low-temperature characteristics were determined by strength flexural test, commonly used in the Czech Republic for High Modulus Asphalt Mixtures (TP 151), and semi-cylindrical bending test (EN 12697-44). Both of the tests were extended by specimens exposed to artificial long-term aging (EN 12697-52) - storing at 85° C for 5 days. The results were compared with characteristics of binders for finding a suitable correlation between characteristics of binders and asphalt mixtures.

Regional variation in wood modulus of elasticity (stiffness) and modulus of rupture (strength) of planted loblolly pine in the United States

Treesearch

Antony Finto; Lewis Jordan; Laurence R. Schimleck; Alexander Clark; Ray A. Souter; Richard F. Daniels

2011-01-01

Modulus of elasticity (MOE), modulus of rupture (MOR), and specific gravity (SG) are important properties for determining the end-use and value of a piece of lumber. This study addressed the variation in MOE, MOR, and SG with physiographic region, tree height, and wood type. Properties were measured from two static bending samples (dimensions 25.4 mm × 25.4 mm × 406.4...

DOE Office of Scientific and Technical Information (OSTI.GOV)

Haker, C.D.; Rix, G.J.; Lai, C.G.

The seismic stability of municipal solid waste (MSW) landfills is often a significant consideration in landfill design. However, until recently, the dynamic properties of the waste material itself, which govern the seismic response of MSW landfills, have often been approximated or assumed. Tests to determine the dynamic properties of the material directly have been limited. Measurements of seismic surface waves were used to determine the dynamic properties of MSW, which are the initial tangent shear modulus and low-strain hysteretic damping ratio. Surface wave tests were performed at three MSW landfills to determine their shear modulus and damping ratio profiles. Surfacemore » wave tests are ideal for measuring the near-surface shear modulus and damping profiles of MSW landfills because the tests are non-invasive, an advantage for testing environmentally sensitive waste material. Factors which influence the dynamic properties of waste including density, confinement, age, and placement techniques are used to interpret the measured shear modulus and damping ratio profiles.« less

Building Resiliency: How To Thrive in Times of Change. An Ideas into Action Guidebook.

ERIC Educational Resources Information Center

Pulley, Mary Lynn; Wakefield, Michael

This is a practicing managers' guide for gaining the ability to thrive during change, for leaders of any kind of organization. Resiliency is defined, its components described, and its importance explained. Concrete examples of resiliency and questions that can determine degree of resiliency are provided. Resiliency is not described as being…

Effects of health empowerment intervention on resilience of adolescents in a tribal area: A study using the Solomon four-groups design.

PubMed

Sarkar, Kaushik; Dasgupta, Aparajita; Sinha, Multipada; Shahbabu, Bhaskar

2017-10-01

Resilience prevents the emergence of stress-related mental health problems among adolescents. Adolescents in tribal areas of India are more prone to develop such problems. The primary objective was to determine the effect of combined life skills-based health empowerment intervention on the resilience of school-going adolescents in a tribal area. The secondary objectives were to determine the effect of the intervention on internal health locus of control and self-determination and to compare the effect of intervention on resilience between non-tribal and tribal adolescents. We conducted this quasi-experimental study using a Solomon four-group design among 742 adolescents in two schools of Purulia, West Bengal, India. Students of the pretested group were examined for resilience using the Child Youth Resilience Measurement scale. A life skills education-based health empowerment intervention was administered among students of the experimental group. Post-test data on resilience, self-determination, internal health locus of control and pathological behaviour was obtained 3 months after the completion of intervention. A multi-level general linear mixed model was constructed to determine the effect of intervention on resilience. Resilience was less among tribal adolescents at baseline. The intervention significantly improved resilience [β Adjusted  = 11.19 (95% CI = 10.55, 11.83], with a greater increase for tribal adolescents [β tribal-nontribal  = 1.53 (95% CI = 0.03, 3.03)]. The intervention also significantly improved internal health locus of control (marginal mean increment 1.38 ± 0.05), self-determination (marginal mean increment 3.71 ± 0.09) and reduced pathological behaviour of the adolescents. Our study informed the current health policy that the existing life skills education-based programme should be reviewed and modified to include generic life skills, and the life skills education-based programme should be coupled with developmental interventions aimed at improving adult education and family climate for optimum effect on mental health and health behaviour of adolescents. Copyright © 2017 Elsevier Ltd. All rights reserved.

Muscle shear elastic modulus is linearly related to muscle torque over the entire range of isometric contraction intensity.

PubMed

Ateş, Filiz; Hug, François; Bouillard, Killian; Jubeau, Marc; Frappart, Thomas; Couade, Mathieu; Bercoff, Jeremy; Nordez, Antoine

2015-08-01

Muscle shear elastic modulus is linearly related to muscle torque during low-level contractions (<60% of Maximal Voluntary Contraction, MVC). This measurement can therefore be used to estimate changes in individual muscle force. However, it is not known if this relationship remains valid for higher intensities. The aim of this study was to determine: (i) the relationship between muscle shear elastic modulus and muscle torque over the entire range of isometric contraction and (ii) the influence of the size of the region of interest (ROI) used to average the shear modulus value. Ten healthy males performed two incremental isometric little finger abductions. The joint torque produced by Abductor Digiti Minimi was considered as an index of muscle torque and elastic modulus. A high coefficient of determination (R(2)) (range: 0.86-0.98) indicated that the relationship between elastic modulus and torque can be accurately modeled by a linear regression over the entire range (0% to 100% of MVC). The changes in shear elastic modulus as a function of torque were highly repeatable. Lower R(2) values (0.89±0.13 for 1/16 of ROI) and significantly increased absolute errors were observed when the shear elastic modulus was averaged over smaller ROI, half, 1/4 and 1/16 of the full ROI) than the full ROI (mean size: 1.18±0.24cm(2)). It suggests that the ROI should be as large as possible for accurate measurement of muscle shear modulus. Copyright © 2015 Elsevier Ltd. All rights reserved.

Childhood Resilience of African American School Leaders

ERIC Educational Resources Information Center

Hauser, Angella

2014-01-01

The purpose of this study was to determine what African Americans who serve in upper-level school leadership positions and who have faced significant barriers as children attribute to their resilience and success. I focused on individual resilience, using the definition summarized by VanBreda (2001): "[R]esilience theory addresses the…

Teachers' (Mis)Understandings of Resilience

ERIC Educational Resources Information Center

Green, Deborah; Oswald, Murray; Spears, Barbara

2007-01-01

This study aimed to extend previous studies into resilience, by identifying the roles that teachers played in fostering resilience (N=57: females n=43; and males n=14). A quantitative scale was administered to teachers in South Australia's Catholic education sector to determine the extent to which they were involved in fostering resilience. A…

An enhanced method to determine the Young’s modulus of technical single fibres by means of high resolution digital image correlation

NASA Astrophysics Data System (ADS)

Huether, Jonas; Rupp, Peter; Kohlschreiber, Ina; André Weidenmann, Kay

2018-04-01

To obtain mechanical tensile properties of materials it is customary to equip the specimen directly with a device to measure strain and Young’s modulus correctly and only within the measuring length defined by the standards. Whereas a variety of tools such as extensometers, strain gauges and optical systems are available for specimens on coupon level, no market-ready tools to measure strains of single fibres during single fibre tensile tests are available. Although there is a standard for single fibre testing, the procedures described there are only capable of measuring strains of the whole testing setup rather than the strain of the fibre. Without a direct strain measurement on the specimen, the compliance of the test rig itself influences the determination of the Young’s modulus. This work aims to fill this gap by establishing an enhanced method to measure strains directly on the tested fibre and thus provide accurate values for Young’s modulus. It is demonstrated that by applying and then optically tracking fluorescing polymeric beads on single glass fibres, Young’s modulus is determined directly and with high repeatability, without a need to measure at different measuring lengths or compensating for the system compliance. Employing this method to glass fibres, a Young’s modulus of approximately 82.5 GPa was determined, which is in the range of values obtained by applying a conventional procedure. This enhanced measuring technology achieves high accuracy and repeatability while reducing scatter of the data. It was demonstrated that the fluorescing beads do not affect the fibre properties.

Correlation between macro- and nano-scopic measurements of carbon nanostructured paper elastic modulus

DOE Office of Scientific and Technical Information (OSTI.GOV)

Omar, Yamila M.; Al Ghaferi, Amal, E-mail: aalghaferi@masdar.ac.ae, E-mail: mchiesa@masdar.ac.ae; Chiesa, Matteo, E-mail: aalghaferi@masdar.ac.ae, E-mail: mchiesa@masdar.ac.ae

2015-07-20

Extensive work has been done in order to determine the bulk elastic modulus of isotropic samples from force curves acquired with atomic force microscopy. However, new challenges are encountered given the development of new materials constructed of one-dimensional anisotropic building blocks, such as carbon nanostructured paper. In the present work, we establish a reliable framework to correlate the elastic modulus values obtained by amplitude modulation atomic force microscope force curves, a nanoscopic technique, with that determined by traditional macroscopic tensile testing. In order to do so, several techniques involving image processing, statistical analysis, and simulations are used to find themore » appropriate path to understand how macroscopic properties arise from anisotropic nanoscale components, and ultimately, being able to calculate the value of bulk elastic modulus.« less

Measurement of Young's modulus in the in vivo human vocal folds.

PubMed

Tran, Q T; Berke, G S; Gerratt, B R; Kreiman, J

1993-08-01

Currently, surgeons have no objective means to evaluate and optimize results of phonosurgery intraoperatively. Instead, they usually judge the vocal folds subjectively by visual inspection or by listening to the voice. This paper describes a new device that measures Young's (elastic) modulus values for the human vocal fold intraoperatively. Physiologically, the modulus of the vocal fold may be important in determining the nature of vocal fold vibration in normal and pathologic states. This study also reports the effect of recurrent laryngeal nerve stimulation on Young's modulus of the human vocal folds, measured by means of transcutaneous nerve stimulation techniques. Young's modulus increased with increases in current stimulation to the recurrent laryngeal nerve. Ultimately, Young's modulus values may assist surgeons in optimizing the results of various phonosurgeries.

Resonant Acoustic Determination of Complex Elastic Moduli

NASA Technical Reports Server (NTRS)

Brown, David A.; Garrett, Steven L.

1991-01-01

A simple, inexpensive, yet accurate method for measuring the dynamic complex modulus of elasticity is described. Using a 'free-free' bar selectively excited in three independent vibrational modes, the shear modulus is obtained by measuring the frequency of the torsional resonant mode and the Young's modulus is determined from measurement of either the longitudinal or flexural mode. The damping properties are obtained by measuring the quality factor (Q) for each mode. The Q is inversely proportional to the loss tangent. The viscoelastic behavior of the sample can be obtained by tracking a particular resonant mode (and thus a particular modulus) using a phase locked loop (PLL) and by changing the temperature of the sample. The change in the damping properties is obtained by measuring the in-phase amplitude of the PLL which is proportional to the Q of the material. The real and imaginary parts or the complex modulus can be obtained continuously as a function of parameters such as temperature, pressure, or humidity. For homogeneous and isotropic samples only two independent moduli are needed in order to characterize the complete set of elastic constants, thus, values can be obtained for the dynamic Poisson's ratio, bulk modulus, Lame constants, etc.

Determining a membrane's shear modulus, independent of its area-dilatation modulus, via capsule flow in a converging micro-capillary.

PubMed

Dimitrakopoulos, P; Kuriakose, S

2015-04-14

Determination of the elastic properties of the membrane of artificial capsules is essential for the better design of the various devices that are utilized in their engineering and biomedical applications. However this task is complicated owing to the combined effects of the shear and area-dilatation moduli on the capsule deformation. Based on computational investigation, we propose a new methodology to determine a membrane's shear modulus, independent of its area-dilatation modulus, by flowing strain-hardening capsules in a converging micro-capillary of comparable size under Stokes flow conditions, and comparing the experimental measurements of the capsule elongation overshooting with computational data. The capsule prestress, if any, can also be determined with the same methodology. The elongation overshooting is practically independent of the viscosity ratio for low and moderate viscosity ratios, and thus a wide range of capsule fluids can be employed. Our proposed experimental device can be readily produced via glass fabrication while owing to the continuous flow in the micro-capillary, the characterization of a large number of artificial capsules is possible.

Resilience to stress and disturbance, and resistance to Bromus tectorum L. invasion in cold desert shrublands of western North America

USGS Publications Warehouse

Chambers, Jeanne C.; Bradley, Bethany A.; Brown, Cynthia S.; D'Antonio, Carla; Germino, Matthew J.; Grace, James B.; Hardegree, Stuart P.; Miller, Richard F.; Pyke, David A.

2013-01-01

Alien grass invasions in arid and semi-arid ecosystems are resulting in grass–fire cycles and ecosystem-level transformations that severely diminish ecosystem services. Our capacity to address the rapid and complex changes occurring in these ecosystems can be enhanced by developing an understanding of the environmental factors and ecosystem attributes that determine resilience of native ecosystems to stress and disturbance, and resistance to invasion. Cold desert shrublands occur over strong environmental gradients and exhibit significant differences in resilience and resistance. They provide an excellent opportunity to increase our understanding of these concepts. Herein, we examine a series of linked questions about (a) ecosystem attributes that determine resilience and resistance along environmental gradients, (b) effects of disturbances like livestock grazing and altered fire regimes and of stressors like rapid climate change, rising CO2, and N deposition on resilience and resistance, and (c) interacting effects of resilience and resistance on ecosystems with different environmental conditions. We conclude by providing strategies for the use of resilience and resistance concepts in a management context. At ecological site scales, state and transition models are used to illustrate how differences in resilience and resistance influence potential alternative vegetation states, transitions among states, and thresholds. At landscape scales management strategies based on resilience and resistance—protection, prevention, restoration, and monitoring and adaptive management—are used to determine priority management areas and appropriate actions.

Improvements in Resilience, Stress, and Somatic Symptoms Following Online Resilience Training

PubMed Central

Smith, Brad; Shatté, Andrew; Perlman, Adam; Siers, Michael; Lynch, Wendy D.

2018-01-01

Objective: To determine if participation in an online resilience program impacts resilience, stress, and somatic symptoms. Methods: Approximately 600 enrollees in the meQuilibrium resilience program received a series of brief, individually prescribed video, and text training modules in a user-friendly format. Regression models tested how time in the program affected change in resilience from baseline and how changes in resilience affected change in stress and reported symptoms. Results: A significant dose–response was detected, where increases in the time spent in training corresponded to greater improvements in resilience. Degree of change in resilience predicted the magnitude of reduction in stress and symptoms. Participants with the lowest resilience level at baseline experienced greater improvements. Conclusion: Interaction with the online resilience training program had a positive effect on resilience, stress, and symptoms in proportion to the time of use. PMID:28820863

Resilient and Corrosion-Proof Rolling Element Bearings Made from Superelastic Ni-Ti Alloys for Aerospace Mechanism Applications

NASA Technical Reports Server (NTRS)

DellaCorte, Christopher; Noebe, Ronald D.; Stanford, Malcolm; Padula, Santo A.

2011-01-01

Mechanical components (bearings, gears, mechanisms) typically utilize hard materials to minimize wear and attain long life. In such components, heavily loaded contact points (e.g., meshing gear teeth, bearing ball-raceway contacts) experience high contact stresses. The combination of high hardness, heavy loads and high elastic modulus often leads to damaging contact stress. In addition, mechanical component materials, such as tool steel or silicon nitride exhibit limited recoverable strain (typically less than 1 percent). These material attributes can lead to Brinell damage (e.g., denting) particularly during transient overload events such as shock impacts that occur during the launching of space vehicles or the landing of aircraft. In this paper, a superelastic alloy, 60NiTi, is considered for rolling element bearing applications. A series of Rockwell and Brinell hardness, compressive strength, fatigue and tribology tests are conducted and reported. The combination of high hardness, moderate elastic modulus, large recoverable strain, low density, and intrinsic corrosion immunity provide a path to bearings largely impervious to shock load damage. It is anticipated that bearings and components made from alloys with such attributes can alleviate many problems encountered in advanced aerospace applications.

Method of measuring material properties of rock in the wall of a borehole

DOEpatents

Overmier, David K.

1985-01-01

To measure the modulus of elasticity of the rock in the wall of a borehole, a plug is cut in the borehole wall. The plug, its base attached to the surrounding rock, acts as a short column in response to applied forces. A loading piston is applied to the top of the plug and compression of the plug is measured as load is increased. Measurement of piston load and plug longitudinal deformation are made to determine the elastic modulus of the plug material. Poisson's ratio can be determined by simultaneous measurements of longitudinal and lateral deformation of the plug in response to loading. To determine shear modulus, the top of the plug is twisted while measurements are taken of torsional deformation.

Method of measuring material properties of rock in the wall of a borehole

DOEpatents

Overmier, D.K.

1984-01-01

To measure the modulus of elasticity of the rock in the wall of a borehole, a plug is cut in the borehole wall. The plug, its base attached to the surrounding rock, acts as a short column in response to applied forces. A loading piston is applied to the top of the plug and compression of the plug is measured as load is increased. Measurements of piston load and plug longitudinal deformation are made to determine the elastic modulus of the plug material. Poisson's ratio can be determined by simultaneous measurements of longitudinal and lateral deformation of the plug in response to loading. To determine shear modulus, the top of the plug is twisted while measurements are taken of torsional deformation.

Determination of mechanical properties of some glass fiber reinforced plastics suitable to Wind Turbine Blade construction

NASA Astrophysics Data System (ADS)

Steigmann, R.; Savin, A.; Goanta, V.; Barsanescu, P. D.; Leitoiu, B.; Iftimie, N.; Stanciu, M. D.; Curtu, I.

2016-08-01

The control of wind turbine's components is very rigorous, while the tower and gearbox have more possibility for revision and repairing, the rotor blades, once they are deteriorated, the defects can rapidly propagate, producing failure, and the damages can affect large regions around the wind turbine. This paper presents the test results, performed on glass fiber reinforced plastics (GFRP) suitable to construction of wind turbine blades (WTB). The Young modulus, shear modulus, Poisson's ratio, ultimate stress have been determined using tensile and shear tests. Using Dynamical Mechanical Analysis (DMA), the activation energy for transitions that appear in polyester matrix as well as the complex elastic modulus can be determined, function of temperature.

Investigation to determine the vulnerability of reclaimed land to building collapse using near surface geophysical method

NASA Astrophysics Data System (ADS)

Adewoyin, O. O.; Joshua, E. O.; Akinyemi, M. L.; Omeje, M.; Joel, E. S.

2017-05-01

Adequate knowledge of the geology and the structures of the subsurface would assist engineers in the best way to carry out constructions to avoid building collapse. In this study, near surface seismic refraction method was used to determine the geotechnical parameters of the subsurface, the results obtained were correlated with the result of borehole data drilled in the study area. The results of seismic refraction method delineated mostly two distinct layers with the first layer having the lower geotechnical parameters. It was observed that in the first layer, the Young’s modulus ranged from 0.168 to 0.458 GPa, shear modulus ranged between 0.068 and 0.185 GPa, the bulk modulus ranged between 0.106 and 0.287 GPa while the bearing capacity ranged from 0.083 to 0.139 MPa. On the other hand, in the second layer, the Young’s modulus ranged between 3.717 and 7.018 GPa, shear modulus ranged from 1.500 to 2.830 GPa while the bulk modulus ranged from 2.383 to 4.449 GPa. Significantly, the formation of the second layer appeared to be more competent than the first layer, therefore engineering construction in this geological setting is recommended to be founded on the second layer at depth ranging between 7 and 16 m.

Determination of Young's modulus of individual electrospun nanofibers by microcantilever vibration method

NASA Astrophysics Data System (ADS)

Yuya, Philip A.; Wen, Yongkui; Turner, Joseph A.; Dzenis, Yuris A.; Li, Zheng

2007-03-01

The authors report a technique for measuring Young's modulus of a single electrospun nanofiber using the vibrations of two microcantilevers coupled with the nanofiber. The modulus is calculated from the resonant frequency shift resulting from the nanofiber. Polyacrylonitrile nanofibers (200nm diameter) were collected during electrospinning and wrapped on two similar microcantilevers causing a shift in first resonance from 10.0to19.4kHz. Finite element analysis was used to analyze the frequency shift using images from a scanning electron microscope giving a modulus of the as-spun polyacrylonitrile nanofiber of 26.8GPa.

Temperature Coefficient of the Modulus of Rigidity of Aircraft Instrument Diaphragm and Spring Materials

NASA Technical Reports Server (NTRS)

Brombacher, W G; Melton, E R

1931-01-01

Experimental data are presented on the variation of the modulus of rigidity in the temperature range -20 to +50 degrees C. of a number of metals which are of possible use for elastic elements for aircraft and other instruments. The methods of the torsional pendulum was used to determine the modulus of rigidity and its temperature coefficient for aluminum, duralumin, monel metal, brass, phosphor bronze, coin silver, nickel silver, three high carbon steels, and three alloy steels. It was observed that tensile stress affected the values of the modulus by amounts of 1 per cent or less.

Flexural Vibration Test of a Cantilever Beam with a Force Sensor: Fast Determination of Young's Modulus

ERIC Educational Resources Information Center

Digilov, Rafael M.

2008-01-01

We describe a simple and very inexpensive undergraduate laboratory experiment for fast determination of Young's modulus at moderate temperatures with the aid of a force sensor. A strip-shaped specimen rigidly bolted to the force sensor forms a clamped-free cantilever beam. Placed in a furnace, it is subjected to free-bending vibrations followed by…

Quantum chemical determination of young?s modulus of lignin. Calculations on ß-O-4' model compound

Treesearch

Thomas Elder

2007-01-01

The calculation of Young?s modulus of lignin has been examined by subjecting a dimeric model compound to strain, coupled with the determination of energy and stress. The computational results, derived from quantum chemical calculations, are in agreement with available experimental results. Changes in geometry indicate that modifications in dihedral angles occur in...

Sensitive determination of the Young's modulus of thin films by polymeric microcantilevers

NASA Astrophysics Data System (ADS)

Colombi, Paolo; Bergese, Paolo; Bontempi, Elza; Borgese, Laura; Federici, Stefania; Sylvest Keller, Stephan; Boisen, Anja; Eleonora Depero, Laura

2013-12-01

A method for the highly sensitive determination of the Young's modulus of TiO2 thin films exploiting the resonant frequency shift of a SU-8 polymer microcantilever (MC) is presented. Amorphous TiO2 films with different thickness ranging from 10 to 125 nm were grown at low temperature (90 °C) with subnanometer thickness resolution on SU-8 MC arrays by means of atomic layer deposition. The resonant frequencies of the MCs were measured before and after coating and the elastic moduli of the films were determined by a theoretical model developed for this purpose. The Young's modulus of thicker TiO2 films (>75 nm) was estimated to be about 110 GPa, this value being consistent with the value of amorphous TiO2. On the other hand we observed a marked decrease of the Young's modulus for TiO2 films with a thickness below 50 nm. This behavior was found not to be related to a decrease of the film mass density, but to surface effects according to theoretical predictions on size-dependent mechanical properties of nano- and microstructures.

Mechanical Sensing with Flexible Metallic Nanowires

NASA Astrophysics Data System (ADS)

Dobrokhotov, Vladimir; Yazdanpanah, Mehdi; Pabba, Santosh; Safir, Abdelilah; Cohn, Robert

2008-03-01

A calibrated method of force sensing is demonstrated in which the buckled shape of a long flexible metallic nanowire is interpreted to determine the applied force. Using a nanomanipulator the nanowire is buckled in the chamber of a scanning electron microscope (SEM) and the buckled shapes are recorded in SEM images. Force is determined as a function of deflection for an assumed elastic modulus by fitting the shapes using the generalized elastica model. In this calibration the elastic modulus was determined using an auxiliary AFM measurement, with the needle in the same orientation as in the SEM. Following this calibration the needle was used as a sensor in a different orientation than the AFM coordinates to deflect a suspended PLLA polymer fiber from which the elastic modulus (2.96 GPa) was determined. In this study the same needle remained rigidly secured to the AFM cantilever throughout the entire SEM/AFM calibration procedure and the characterization of the nanofiber.

Profiles of Personal Resiliency for Normative and Clinical Samples of Youth Assessed by the Resiliency Scales for Children and Adolescents[TM

ERIC Educational Resources Information Center

Prince-Embury, Sandra; Steer, Robert A.

2010-01-01

Cluster analyses with the three global scores of the Resiliency Scales for Children and Adolescents[TM] (RSCA) were used to determine personal resiliency profiles within normative (641) and outpatient clinical (285) samples of youth aged 9 to 18 years. Normative and clinical profiles were compared with each other and the clinical profiles were…

Empirical study of alginate impression materials by customized proportioning system

PubMed Central

2016-01-01

PURPOSE Alginate mixers available in the market do not have the automatic proportioning unit. In this study, an automatic proportioning unit for the alginate mixer and controller software were designed and produced for a new automatic proportioning unit. With this device, it was ensured that proportioning operation could arrange weight-based alginate impression materials. MATERIALS AND METHODS The variation of coefficient in the tested groups was compared with the manual proportioning. Compression tension and tear tests were conducted to determine the mechanical properties of alginate impression materials. The experimental data were statistically analyzed using one way ANOVA and Tukey test at the 0.05 level of significance. RESULTS No statistically significant differences in modulus of elastisity (P>0.3), tensional/compresional strength (P>0.3), resilience (P>0.2), strain in failure (P>0.4), and tear energy (P>0.7) of alginate impression materials were seen. However, a decrease in the standard deviation of tested groups was observed when the customized machine was used. To verify the efficiency of the system, powder and powder/water mixing were weighed and significant decrease was observed. CONCLUSION It was possible to obtain more mechanically stable alginate impression materials by using the custom-made proportioning unit. PMID:27826387

A field guide for rapid assessment of post-wildfire recovery potential in sagebrush and pinon-juniper ecosystems in the Great Basin: Evaluating resilience to disturbance and resistance to invasive annual grasses and predicting vegetation response

Treesearch

Richard F. Miller; Jeanne C. Chambers; Mike Pellant

2015-01-01

This field guide provides a framework for rapidly evaluating post-fire resilience to disturbance, or recovery potential, and resistance to invasive annual grasses, and for determining the need and suitability of the burned area for seeding. The framework identifies six primary components that largely determine resilience to disturbance, resistance to invasive grasses,...

The use of discontinuities and functional groups to assess relative resilience in complex systems

USGS Publications Warehouse

Allen, Craig R.; Gunderson, Lance; Johnson, A.R.

2005-01-01

It is evident when the resilience of a system has been exceeded and the system qualitatively changed. However, it is not clear how to measure resilience in a system prior to the demonstration that the capacity for resilient response has been exceeded. We argue that self-organizing human and natural systems are structured by a relatively small set of processes operating across scales in time and space. These structuring processes should generate a discontinuous distribution of structures and frequencies, where discontinuities mark the transition from one scale to another. Resilience is not driven by the identity of elements of a system, but rather by the functions those elements provide, and their distribution within and across scales. A self-organizing system that is resilient should maintain patterns of function within and across scales despite the turnover of specific elements (for example, species, cities). However, the loss of functions, or a decrease in functional representation at certain scales will decrease system resilience. It follows that some distributions of function should be more resilient than others. We propose that the determination of discontinuities, and the quantification of function both within and across scales, produce relative measures of resilience in ecological and other systems. We describe a set of methods to assess the relative resilience of a system based upon the determination of discontinuities and the quantification of the distribution of functions in relation to those discontinuities. ?? 2005 Springer Science+Business Media, Inc.

The role of positive youth development practices in building resilience and enhancing wellbeing for at-risk youth.

PubMed

Sanders, Jackie; Munford, Robyn; Thimasarn-Anwar, Tewaporn; Liebenberg, Linda; Ungar, Michael

2015-04-01

Services that utilise positive youth development practices (PYD) are thought to improve the quality of the service experience leading to better outcomes for at-risk youth. This article reports on a study of 605 adolescents (aged 12-17 years) who were concurrent clients of two or more service systems (child welfare, juvenile justice, additional education, mental health). It was hypothesised that services adopting PYD approaches would be related to increases in youth resilience and better wellbeing outcomes. It was also hypothesised that risks, resilience, service experiences and wellbeing outcomes would differ by age, gender and ethnicity. Youth completed a self-report questionnaire administered individually. Path analysis was used to determine the relationship between risk, service use, resilience and a wellbeing outcome measure. MANOVA was then used to determine patterns of risk, service use, resilience and wellbeing among participants based on their demographic characteristics. Services using PYD approaches were significantly related to higher levels of youth resilience. Similarly, increased resilience was related to increased indicators of wellbeing, suggesting the mediating role of resilience between risk factors and wellbeing outcomes. When professionals adopt PYD practices and work with the positive resources around youth (their own resilience processes) interventions can make a significant contribution to wellbeing outcomes for at-risk youth. Copyright © 2015 Elsevier Ltd. All rights reserved.

The Effect of Annealing on the Elastic Modulus of Orthodontic Wires

NASA Astrophysics Data System (ADS)

Higginbottom, Kyle

Introduction: Nickel Titanium orthodontic wires are currently used in orthodontic treatment due to their heat activated properties and their delivery of constant force. The objective of this study was to determine the effect of annealing on the elastic modulus of Nickel Titanium, Stainless Steel and Beta-titanium (TMA) wires. Different points along the wire were tested in order to determine how far from the annealed ends the elastic modulus of the wires was affected. Methods: Eighty (80) orthodontic wires consisting of 4 equal groups (SS/TMA/Classic NitinolRTM/Super Elastic NitinolRTM) were used as the specimens for this study. All wires were measured and marked at 5mm measurements, and cut into 33.00mm sections. The wires were heated with a butane torch until the first 13.00mm of the wires were red hot. Load deflection tests using an InstronRTM universal testing machine were run at 5mm distances from the end of the wire that had been annealed. The change in elastic modulus was then determined. Results: There was a significant difference (F = 533.001, p = 0.0005) in the change in elastic modulus for the four distances. There was also a significant difference (F = 57.571, p = 0.0005) in the change in elastic modulus for the four wire types. There was a significant interaction (F = 19.601, p = 0.005) between wire type and distance, however this interaction negated the differences between the wires. Conclusion: 1) There are significant differences in the changes in elastic modulus between the areas of the wires within the annealed section and those areas 5mm and 10mm away from the annealed section. The change in elastic modulus within the annealed section was significantly greater at 8 mm than it was at 13mm, and this was significantly greater than 18mm and 23mm (5mm and 10mm beyond the annealed section). However, there was no statistical difference in the change in elastic modulus between 5mm and 10mm away from the annealed section (18mm and 23mm respectively). 2) Regardless of the wire type, no clinically important effects were seen 5mm and 10mm beyond the annealed portion.

Effect of flexure beam geometry and material on the displacement of piezo actuated diaphragm for micropump

NASA Astrophysics Data System (ADS)

Roopa, R.; Navin Karanth, P.; Kulkarni, S. M.

2018-02-01

In this paper, we present a COMSOL analysis of flexure diaphragm for piezo actuated valveless micropump. Diaphragms play an important role in micropumps, till now plane diaphragms are commonly used in micropumps. Use of compliant flexure hinges in diaphragm and other MEMS application is one of the new approach to achieving high deflection in diaphragm at low operating voltage. Flexures hinges in diaphragm acts as simply supported beam. Out-off plane compliance value and stiffness is considered for the selection of proper flexure for diaphragm. Diaphragm material also plays an important role in the diaphragm central deflection. Factor considered for diaphragm material selection is resilience; it is the ratio of yield stress to static modulus. Higher is the resilience will leads to higher deflection generated, it also imparts good compliance. Based on the resilience beryllium copper, stainless steel and brass materials are selected for diaphragm analysis. Simulations have been performed using COMSOL multiphysics. This study reports the effect of flexure hinge geometry and diaphragm material on the central deflection of diaphragms and compared with existing plane diaphragm. Simulation results illustrates that the deflection of three flexure diaphragm with 2mm width and 2mm length flexure is 6.75µm for stainless steel, 10.89 for beryllium copper and 12.10µm for brass, at 140V which is approximately twice that of plane diaphragm deflection. The maximum in both plane and three flexure diaphragm deflection is obtained for brass diaphragm compared to stainless steel and beryllium copper.

Measuring the rebound resilience of a bouncing ball

NASA Astrophysics Data System (ADS)

Wadhwa, Ajay

2012-09-01

Some balls which are made of high-quality rubber (an elastomeric) material, such as tennis or squash balls, could be used for the determination of an important property of such materials called resilience. Since a bouncing ball involves a single impact we call this property 'rebound resilience' and express it as the ratio of the rebound height to the initial drop height of the ball. We determine the rebound resilience for three different types of ball by calculating the coefficient of restitution of the ball-surface combination from the experimentally measurable physical quantities, such as initial drop height and time interval between successive bounces. Using these we also determine the contact time of balls with the surface of impact. For measurements we have used audio, motion and surface-temperature sensors that were interfaced through a USB port with a computer.

Gender Differences in Resilience of Academic Deans

ERIC Educational Resources Information Center

Isaacs, Albert J.

2014-01-01

The purpose of this investigation was to determine the difference in the levels of resilience characteristics between male and female deans within a state university system. Resilience is the ability to operate in a changing environment while consistently maintaining one's effectiveness. This quantitative study utilized the survey, Personal…

Mapping Resilience Pathways of Indigenous Youth in Five Circumpolar Communities

PubMed Central

Allen, James; Hopper, Kim; Wexler, Lisa; Kral, Michael; Rasmus, Stacy; Nystad, Kristine

2014-01-01

This introduction to the special issue Indigenous Youth Resilience in the Arctic reviews relevant resilience theory and research, with particular attention to Arctic Indigenous youth. The role of social determinants and community resilience processes in Indigenous circumpolar settings are overviewed, as are emergent Indigenous resilience frameworks. The distinctive role for qualitative inquiry in understanding these frameworks is emphasized, as is the uniquely informative lens youth narratives offer in understanding Indigenous, cultural, and community resilience processes during times of social transition. We then describe key elements of the Circumpolar Indigenous Pathways to Adulthood study cross-site methods, including sampling, design, procedures, and analytic strategies. PMID:23965730

Analysis of the variation in the determination of the shear modulus of the erythrocyte membrane: Effects of the constitutive law and membrane modeling

PubMed Central

Dimitrakopoulos, P.

2013-01-01

Despite research spanning several decades, the exact value of the shear modulus Gs of the erythrocyte membrane is still ambiguous, and a wealth of studies, using measurements based on micropipette aspirations, ektacytometry systems and other flow chambers, and optical tweezers as well as application of several models have found different average values in the range 2–10 µN/m. Our study shows that different methodologies have predicted the correct shear modulus for the specific membrane modeling employed, i.e. the variation in the shear modulus determination results from the specific membrane modeling. Available experimental findings from ektacytometry systems and optical tweezers suggest that the dynamics of the erythrocyte membrane is strain-hardening at both moderate and large deformations. Thus the erythrocyte shear modulus cannot be determined accurately using strain-softening models (such as the neo-Hookean and Evans laws) or strain-softening/strain-hardening models (such as the Yeoh law) which overestimate the erythrocyte shear modulus. According to our analysis, the only available strain-hardening constitutive law, the Skalak et al. law, is able to match well both deformation-shear rate data from ektacytometry and force-extension data from optical tweezers at moderate and large strains, using an average value of the shear modulus of Gs = 2.4–2.75 µN/m, i.e. very close to that found in the linear regime of deformations via force-extension data from optical tweezers, Gs = 2.5±0.4 µN/m. In addition, our analysis suggests that a standard deviation in Gs of 0.4–0.5 µN/m (owing to the inherent differences between erythrocytes within a large population) describes well the findings from optical tweezers at small and large strains as well as from micro-pipette aspirations. PMID:22680508

A new method to study he effective shear modulus of shocked material

NASA Astrophysics Data System (ADS)

Xiaojuan, Ma; Fusheng, Liu

2013-06-01

Shear modulus is a crucial material parameter for description of mechanical behavior. However, at strong shock compression, it is generally deduced from the longitudinal and bulk sound velocity evaluated by unloading wave profile measurement. Here, a new method called the disturbed amplitude damping method of shock wave is presented, that can directly measure the shear modulus of material. This method relies on the correlation between the shear modulus of shock compressed state and amplitude damping and oscillation of an initial sinusoidal disturbance on shock front in concerned substance. Two important steps are required to determine the shear modulus of material. The first is to measure the damping and oscillation feature of disturbance by the flyer impacted method. The second is to find the quantitative relationship between the disturbed amplitude damping and shear modulus by the finite difference method which is applied to obtain the numerical solutions for disturbance amplitude damping behavior of sinusoidal shock front in flyer impacted flow field. When aluminum shocked to 80 GPa is taken as an example, the shape of perturbed shock front and its disturbed amplitude development with propagation distance, are approximately mapped out. The figure shows an oscillatory damping characteristic. At the early stage the perturbation amplitude on the shock front experiences a decaying process until to zero point, then it rises to a maximum but in reverse phase, and then it decays again. Comparing these data with those simulated using the SCG constitutive model, the effective shear modulus for aluminum shocked to 80 GPa is determined to be about 90 GPa, which is higher than the result given by Yu.

Quantifying Young's moduli of protein fibrils and particles with bimodal force spectroscopy.

PubMed

Gilbert, Jay; Charnley, Mirren; Cheng, Christopher; Reynolds, Nicholas P; Jones, Owen G

2017-10-19

Force spectroscopy is a means of obtaining mechanical information of individual nanometer-scale structures in composite materials, such as protein assemblies for use in consumer films or gels. As a recently developed force spectroscopy technique, bimodal force spectroscopy relates frequency shifts in cantilevers simultaneously excited at multiple frequencies to the elastic properties of the contacted material, yet its utility for quantitative characterization of biopolymer assemblies has been limited. In this study, a linear correlation between experimental frequency shift and Young's modulus of polymer films was used to calibrate bimodal force spectroscopy and quantify Young's modulus of two protein nanostructures: β-lactoglobulin fibrils and zein nanoparticles. Cross-sectional Young's modulus of protein fibrils was determined to be 1.6 GPa while the modulus of zein nanoparticles was determined as 854 MPa. Parallel measurement of β-lactoglobulin fibril by a competing pulsed-force technique found a higher cross-sectional Young's modulus, highlighting the importance of comparative calibration against known standards in both pulsed and bimodal force spectroscopies. These findings demonstrate a successful procedure for measuring mechanical properties of individual protein assemblies with potential use in biological or packaging applications using bimodal force spectroscopy.

Resilient Agricultural Educators: Taking Stress to the Next Level

ERIC Educational Resources Information Center

Thieman, Erica B.; Henry, Anna L.; Kitchel, Tracy

2012-01-01

The goal for this research synthesis was to introduce the concept of resilience to agricultural education and determine if further research is warranted on resilience and positive psychology as they relate to the agricultural educator. The current environment of public schools coupled with the ever-burgeoning responsibilities placed upon the…

Experimental and theoretical modal analysis of full-sized wood composite panels supported on four nodes

Treesearch

Cheng Guan; Houjiang Zhang; Xiping Wang; Hu Miao; Lujing Zhou; Fenglu Liu

2017-01-01

Key elastic properties of full-sized wood composite panels (WCPs) must be accurately determined not only for safety, but also serviceability demands. In this study, the modal parameters of full-sized WCPs supported on four nodes were analyzed for determining the modulus of elasticity (E) in both major and minor axes, as well as the in-plane shear modulus of panels by...

Stress wave velocity and dynamic modulus of elasticity of yellow-poplar ranging from 100 to 10 percent moisture content

Treesearch

Jody D. Gray; Shawn T. Grushecky; James P. Armstrong

2008-01-01

Moisture content has a significant impact on mechanical properties of wood. In recent years, stress wave velocity has been used as an in situ and non-destructive method for determining the stiffness of wooden elements. The objective of this study was to determine what effect moisture content has on stress wave velocity and dynamic modulus of elasticity. Results...

The contribution of individual psychological resilience in determining the professional quality of life of Australian nurses

PubMed Central

Hegney, Desley G.; Rees, Clare S.; Eley, Robert; Osseiran-Moisson, Rebecca; Francis, Karen

2015-01-01

Research Topic: The aim of this study was to determine the relative contribution of trait negative affect and individual psychological resilience in explaining the professional quality of life of nurses. Materials and Methods: One thousand, seven hundred and forty-three Australian nurses from the public, private, and aged care sectors completed an online Qualtrics survey. The survey collected demographic data as well as measures of depression, anxiety and stress, trait negative affect, resilience, and professional quality of life. Results: Significant positive relationships were observed between anxiety, depression and stress, trait negative affectivity, burnout, and secondary traumatic stress (compassion fatigue). Significant negative relationships were observed between each of the aforementioned variables and resilience and compassion satisfaction (CS). Results of mediated regression analysis indicated that resilience partially mediates the relationship between trait negative affect and CS. Conclusion: Results confirm the importance of both trait negative affect and resilience in explaining positive aspects of professional quality of life. Importantly, resilience was confirmed as a key variable impacting levels of CS and thus a potentially important variable to target in interventions aimed at improving nurse’s professional quality of life. PMID:26539150

[Personal resources relevant to psychological well-being in nursing].

PubMed

Arrogante, O; Pérez-García, A M; Aparicio-Zaldívar, E G

2016-01-01

To determine differences in social support, resilience, coping, and psychological well-being (PWB) among intensive care nursing and nursing staff of other hospital services, as well as to establish a structural model in these professionals where relevant personal resources to PWB were included. Correlational and cross-sectional study. A sample of 208 nursing professionals from University Hospital of Fuenlabrada (Madrid) took part in the study. This sample consisted of nurses (n=133), nursing assistants (n=61), and midwives (n=14), of whom 44 worked in intensive care unit, 50 in other special units, and 114 in wards. Social Support Subscale, 10-Item CD-RISC (resilience), Brief-Cope (coping), Scales of PWB, and sociodemographic variables. No differences were found in any assessed psychological variables as regards hospital service worked in. A structural model was found and showed that social support, resilience, and coping determined PWB of nursing professionals. The most important personal resource was coping strategies, which determined PWB directly (β=0.68). Social support influenced PWB directly (β=0.33), and indirectly (β=0.32), whereas resilience influenced it indirectly (β=0.57). Differences in PWB, coping, social support and resilience are not determined by hospital service. Coping strategies focused on engagement (or adaptive), social support, and resilience, constitute three relevant personal resources that determine the PWB of nursing staff, which can be developed and improved by specific programs. The most important PWB dimensions are self-acceptance and environment mastery. Copyright © 2015 Elsevier España, S.L.U. y SEEIUC. All rights reserved.

Friction of sodium alginate hydrogel scaffold fabricated by 3-D printing.

PubMed

Yang, Qian; Li, Jian; Xu, Heng; Long, Shijun; Li, Xuefeng

2017-04-01

A rapid prototyping technology, formed by three-dimensional (3-D) printing and then crosslinked by spraying Ca 2+ solution, is developed to fabricate a sodium alginate (SA) hydrogel scaffold. The porosity, swelling ratio, and compression modulus of the scaffold are investigated. A friction mechanism is developed by studying the reproducible friction behavior. Our results show that the scaffold can have 3-D structure with a porosity of 52%. The degree of swelling of the SA hydrogel scaffold is 8.5, which is nearly the same as bulk SA hydrogel. SA hydrogel exhibits better compressive resilience than bulk hydrogel despite its lower compressive modulus compared to bulk hydrogel. The SA hydrogel scaffold exhibits a higher frictional force at low sliding velocity (10 -6 to 10 -3  m/s) compared to bulk SA hydrogel, and they are equal at high sliding velocity (10 -2 to 1 m/s). For a small pressure (0.3 kPa), the SA hydrogel scaffold shows good friction reproducibility. In contrast, bulk SA hydrogel shows poor reproducibility with respect to friction behavior. The differences in friction behaviors between the SA hydrogel scaffold and bulk SA hydrogel are related to the structure of the scaffold, which can keep a stable hydrated lubrication layer.

Performance characterizations of asphalt binders and mixtures incorporating silane additive ZycoTherm

NASA Astrophysics Data System (ADS)

Hasan, Mohd Rosli Mohd; Hamzah, Meor Othman; Yee, Teh Sek

2017-10-01

Experimental works were conducted to evaluate the properties of asphalt binders and mixtures produced using a relatively new silane additive, named ZycoTherm. In this study, 0.1wt% ZycoTherm was blended with asphalt binder to enable production of asphalt mixture at lower than normal temperatures, as well as improve mix workability and compactability. Asphalt mixture performances towards pavement distresses in tropical climate region were also investigated. The properties of control asphalt binders (60/70 and 80/10 penetration grade) and asphalt binders incorporating 0.1% ZycoTherm were reported based on the penetration, softening point, rotational viscosity, complex modulus and phase angle. Subsequently, to compare the performance of asphalt mixture incorporating ZycoTherm with the control asphalt mixture, cylindrical samples were prepared at recommended temperatures and air voids depending on the binder types and test requirements. The samples were tested for indirect tensile strength (ITS), resilient modulus, dynamic creep, Hamburg wheel tracking and moisture induced damage. From compaction data using the Servopak gyratory compactor, specimen prepared using ZycoTherm exhibit higher workability and compactability compared to the conventional mixture. From the mixture performance test results, mixtures prepared with ZycoTherm showed comparable if not better performance than the control sample in terms of the resistance to moisture damage, permanent deformation and cracking.

Quantifying and measuring cyber resiliency

NASA Astrophysics Data System (ADS)

Cybenko, George

2016-05-01

Cyber resliency has become an increasingly attractive research and operational concept in cyber security. While several metrics have been proposed for quantifying cyber resiliency, a considerable gap remains between those metrics and operationally measurable and meaningful concepts that can be empirically determined in a scientific manner. This paper describes a concrete notion of cyber resiliency that can be tailored to meet specific needs of organizations that seek to introduce resiliency into their assessment of their cyber security posture.

Classical continuum theory limits to determine the size-dependency of mechanical properties of GaN NWs

NASA Astrophysics Data System (ADS)

Zamani Kouhpanji, Mohammad Reza; Behzadirad, Mahmoud; Busani, Tito

2017-12-01

We used the stable strain gradient theory including acceleration gradients to investigate the classical and nonclassical mechanical properties of gallium nitride (GaN) nanowires (NWs). We predicted the static length scales, Young's modulus, and shear modulus of the GaN NWs from the experimental data. Combining these results with atomic simulations, we also found the dynamic length scale of the GaN NWs. Young's modulus, shear modulus, static, and dynamic length scales were found to be 318 GPa, 131 GPa, 8 nm, and 8.9 nm, respectively, usable for demonstrating the static and dynamic behaviors of GaN NWs having diameters from a few nm to bulk dimensions. Furthermore, the experimental data were analyzed with classical continuum theory (CCT) and compared with the available literature to illustrate the size-dependency of the mechanical properties of GaN NWs. This practice resolves the previous published discrepancies that happened due to the limitations of CCT used for determining the mechanical properties of GaN NWs and their size-dependency.

Measurement of the elastic modulus of a multi-wall boron nitride nanotube

NASA Astrophysics Data System (ADS)

Chopra, Nasreen G.; Zettl, A.

1998-02-01

We have experimentally determined the elastic properties of an individual multi-wall boron nitride (BN) nanotube. From the thermal vibration amplitude of a cantilevered BN nanotube observed in a transmission electron microscope, we find the axial Young's modulus to be 1.22 ± 0.24 TPa, a value consistent with theoretical estimates. The observed Young's modulus exceeds that of all other known insulating fibers. Our elasticity results confirm that BN nanotubes are highly crystalline with very few defects.

Processes contributing to resilience of coastal wetlands to sea-level rise

USGS Publications Warehouse

Stagg, Camille L.; Krauss, Ken W.; Cahoon, Donald R.; Cormier, Nicole; Conner, William H.; Swarzenski, Christopher M.

2016-01-01

The objectives of this study were to identify processes that contribute to resilience of coastal wetlands subject to rising sea levels and to determine whether the relative contribution of these processes varies across different wetland community types. We assessed the resilience of wetlands to sea-level rise along a transitional gradient from tidal freshwater forested wetland (TFFW) to marsh by measuring processes controlling wetland elevation. We found that, over 5 years of measurement, TFFWs were resilient, although some marginally, and oligohaline marshes exhibited robust resilience to sea-level rise. We identified fundamental differences in how resilience is maintained across wetland community types, which have important implications for management activities that aim to restore or conserve resilient systems. We showed that the relative importance of surface and subsurface processes in controlling wetland surface elevation change differed between TFFWs and oligohaline marshes. The marshes had significantly higher rates of surface accretion than the TFFWs, and in the marshes, surface accretion was the primary contributor to elevation change. In contrast, elevation change in TFFWs was more heavily influenced by subsurface processes, such as root zone expansion or compaction, which played an important role in determining resilience of TFFWs to rising sea level. When root zone contributions were removed statistically from comparisons between relative sea-level rise and surface elevation change, sites that previously had elevation rate deficits showed a surplus. Therefore, assessments of wetland resilience that do not include subsurface processes will likely misjudge vulnerability to sea-level rise.

Changes in tree resistance, recovery and resilience across three successive extreme droughts in the northeast Iberian Peninsula.

PubMed

Serra-Maluquer, X; Mencuccini, M; Martínez-Vilalta, J

2018-05-01

Understanding which variables affect forest resilience to extreme drought is key to predict future dynamics under ongoing climate change. In this study, we analyzed how tree resistance, recovery and resilience to drought have changed along three consecutive droughts and how they were affected by species, tree size, plot basal area (as a proxy for competition) and climate. We focused on the three most abundant pine species in the northeast Iberian Peninsula: Pinus halepensis, P. nigra and P. sylvestris during the three most extreme droughts recorded in the period 1951-2010 (occurred in 1986, 1994, and 2005-2006). We cored trees from permanent sample plots and used dendrochronological techniques to estimate resistance (ability to maintain growth level during drought), recovery (growth increase after drought) and resilience (capacity to recover pre-drought growth levels) in terms of tree stem basal area increment. Mixed-effects models were used to determine which tree- and plot-level variables were the main determinants of resistance, recovery and resilience, and to test for differences among the studied droughts. Larger trees were significantly less resistant and resilient. Plot basal area effects were only observed for resilience, with a negative impact only during the last drought. Resistance, recovery and resilience differed across the studied drought events, so that the studied populations became less resistant, less resilient and recovered worse during the last two droughts. This pattern suggests an increased vulnerability to drought after successive drought episodes.

Modulus of Elasticity and Thermal Expansion Coefficient of ITO Film

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carter, Austin D.; Elhadj, S.

2016-06-24

The purpose of this experiment was to determine the modulus of elasticity (E) and thermal expansion coefficient (α) of RF sputtered Indium Tin Oxide (ITO) as a function of temperature (T), and to collect ITO film stress data. In order to accomplish that goal, the Toho FLX-2320-S thin film stress measurement machine was used to collect both single stress and stress-temperature data for ITO coated fused silica and sapphire substrates. The stress measurement function of the FLX-2320-S cannot be used to calculate the elastic modulus of the film because the Stoney formula incorporates the elastic modulus of the substrate, rathermore » than of the film itself.« less

A novel critical infrastructure resilience assessment approach using dynamic Bayesian networks

NASA Astrophysics Data System (ADS)

Cai, Baoping; Xie, Min; Liu, Yonghong; Liu, Yiliu; Ji, Renjie; Feng, Qiang

2017-10-01

The word resilience originally originates from the Latin word "resiliere", which means to "bounce back". The concept has been used in various fields, such as ecology, economics, psychology, and society, with different definitions. In the field of critical infrastructure, although some resilience metrics are proposed, they are totally different from each other, which are determined by the performances of the objects of evaluation. Here we bridge the gap by developing a universal critical infrastructure resilience metric from the perspective of reliability engineering. A dynamic Bayesian networks-based assessment approach is proposed to calculate the resilience value. A series, parallel and voting system is used to demonstrate the application of the developed resilience metric and assessment approach.

Measures of emergency preparedness contributing to nursing home resilience.

PubMed

Lane, Sandi J; McGrady, Elizabeth

2017-12-13

Resilience approaches have been successfully applied in crisis management, disaster response, and high reliability organizations and have the potential to enhance existing systems of nursing home disaster preparedness. This study's purpose was to determine how the Center for Medicare and Medicaid Services (CMS) "Emergency Preparedness Checklist Recommended Tool for Effective Health Care Facility Planning" contributes to organizational resilience by identifying the benchmark resilience items addressed by the CMS Emergency Preparedness Checklist and items not addressed by the CMS Emergency Preparedness Checklist, and to recommend tools and processes to improve resilience for nursing homes. The CMS Emergency Preparedness Checklist items were compared to the Resilience Benchmark Tool items; similar items were considered matches. Resilience Benchmark Tool items with no CMS Emergency Preparedness Checklist item matches were considered breaches in nursing home resilience. The findings suggest that the CMS Emergency Preparedness Checklist can be used to measure some aspects of resilience, however, there were many resilience factors not addressed. For nursing homes to prepare and respond to crisis situations, organizations need to embrace a culture that promotes individual resilience-related competencies that when aggregated enable the organization to improve its resiliency. Social workers have the skills and experience to facilitate this change.

Determining the Young's modulus of a cellular titanium implant by FEM simulation

NASA Astrophysics Data System (ADS)

Loginov, Yu. N.; Golodnov, A. I.; Stepanov, S. I.; Kovalev, E. Yu.

2017-12-01

The role of additive manufacturing is noted for the construction of titanium medical implants. The purpose of the study is to determine the Young's modulus of cellular titanium implants, which is based on calculations performed by finite element analysis. A honeycomb structure from intersecting cylinder surfaces is offered for the implant made of the Ti-6Al-4V alloy. Boundary conditions are stated for the loading of the implant structure. It is demonstrated that the Young's modulus can be reduced more than three times comparing to a solid titanium alloy. Zones of strain and stress localization located near the abutment of the cylindrical surfaces. Recommendations for the further improvement of the implant architecture are generated.

Influence of hydraulic hysteresis on the mechanical behavior of unsaturated soils and interfaces

NASA Astrophysics Data System (ADS)

Khoury, Charbel N.

Unsaturated soils are commonly widespread around the world, especially at shallow depths from the surface. The mechanical behavior of this near surface soil is influenced by the seasonal variations such as rainfall or drought, which in turn may have a detrimental effect on many structures (e.g. retaining walls, shallow foundations, mechanically stabilized earth walls, soil slopes, and pavements) in contact with it. Thus, in order to better understand this behavior, it is crucial to study the complex relationship between soil moisture content and matric suction (a stress state variable defined as pore air pressure minus pore water pressure) known as the Soil Water Characteristic Curve (SWCC). In addition, the influence of hydraulic hysteresis on the behavior of unsaturated soils, soil-structure interaction (i.e. rough and smooth steel interfaces, soil-geotextile interfaces) and pavement subgrade (depicted herein mainly by resilient modulus, Mr) was also studied. To this end, suction-controlled direct shear tests were performed on soils, rough and smooth steel interfaces and geotextile interface under drying (D) and wetting after drying (DW). The shearing behavior is examined in terms of the two stress state variables, matric suction and net normal stress. Results along the D and DW paths indicated that peak shear strength increased with suction and net normal stress; while in general, the post peak shear strength was not influenced by suction for rough interfaces and no consistent trend was observed for soils and soil-geotextiles interfaces. Contrary to saturated soils, results during shearing at higher suction values (i.e. 25 kPa and above) showed a decrease in water content eventhough the sample exhibited dilation. A behavior postulated to be related to disruption of menisci and/or non-uniformity of pore size which results in an increase in localized pore water pressures. Interestingly, wetting after drying (DW) test results showed higher peak and post peak shear strength than that of the drying (D) tests. This is believed to be the result of many factors such as: (1) cyclic suction stress loading, (2) water content (less on wetting than drying), and (3) type of soil. The cyclic suction loading may have induced irrecoverable plastic strains, resulting in stiffer samples for wetting tests as compared to drying. Additionally, water may be acting as a lubricant and thus resulting in lower shear strength for test samples D with higher water contents than DW samples. Furthermore, various shear strength models were investigated for their applicability to the experimental data. Models were proposed for the prediction of shear strength with suction based on the SWCC. The models are able to predict the shear strength of unsaturated soil and interfaces due to drying and wetting (i.e. hydraulic hysteresis) by relating directly to the SWCC. The proposed models were used and partly validated by predicting different test results from the literature. In addition, an existing elastoplastic constitutive model was investigated and validated by comparing the predicted and experimental (stress-displacement, volume change behavior) results obtained from rough and geotextile interface tests. This study also explores the effect of hydraulic hysteresis on the resilient modulus (Mr) of subgrade soils. Suction-controlled Mr tests were performed on compacted samples along the primary drying, wetting, secondary drying and wetting paths. Two test types were performed to check the effect of cyclic deviatoric stress loading on the results. First, M r tests were performed on the same sample at each suction (i.e. 25, 50, 75, 100 kPa) value along all the paths (drying, wetting etc.). A relationship between resilient modulus (Mr) and matric suction was obtained and identified as the resilient modulus characteristic curve (MRCC). MRCC results indicated that Mr increased with suction along the drying curve. On the other hand, results on the primary wetting indicated higher Mr than that of the primary drying and the secondary drying. The second type of test was performed at selected suction without subjecting the sample to previous Mr tests. Results indicated that Mr compared favorably with the other type of test (i.e. with previous M r testing), which indicates that the cyclic deviatoric stress loading influence was not as significant as the hydraulic hysteresis (i.e. cyclic suction stress loading). A new model to predict the MRCC results during drying and wetting (i.e., hydraulic hysteresis) is proposed based on the SWCC hysteresis. The model predicted favorably the drying and then the wetting results using the SWCC at all stress levels. (Abstract shortened by UMI.)

Resilience and Psychological Distress in Psychology and Medical Students.

PubMed

Bacchi, Stephen; Licinio, Julio

2017-04-01

The authors investigated levels of resilience and psychological distress in medical and psychology students, factors that may affect these levels, the relationship between resilience and psychological distress, and student opinion on causes of stress and possible interventions. A voluntary anonymous online survey was distributed to University of Adelaide medical and psychology students. Medical and psychology students (n = 560; response rate = 24.7%) had similar mean resilience and psychological distress scores, and 47.9% of medical students and 55.1% of psychology students were psychologically distressed. Higher levels of resilience were associated with lower levels of distress (p < 0.001). Students supported resilience-based interventions, greater financial support, clearer learning objectives and more continuous assessment as potential means to reduce the effects of stress. Higher levels of resilience were associated with lower levels of psychological distress. Further studies are required to determine the efficacy of resilience-based interventions in these groups.

Enhancing scientist-manager relationships to foster ecosystem resilience

Treesearch

Melanie M. Colavito

2015-01-01

This extended abstract describes the preliminary results of a study that sought to determine the most effective ways to develop and apply scientific information about resilience for on-the-ground management. Interviews were conducted with scientists, managers, and other stakeholders in the Southwest U.S. following a workshop on ecosystem resilience held in Tucson,...

Developing Resilient Schools and Resilient Students. Research Brief #19.

ERIC Educational Resources Information Center

Pisapia, John; Westfall, Amy

Recent research by the Metropolitan Educational Research Consortium has led to the development of a resiliency model that helps explain why some at-risk students actually do well in school. The recent investigations have determined that some students develop traits that enable them to be successful in school. The model suggests that four…

Dynamic determination of modulus of elasticity of full-size wood composite panels using a vibration method

Treesearch

Cheng Guan; Houjiang Zhang; Lujing Zhou; Xiping Wang

2015-01-01

A vibration testing method based on free vibration theory in a ‘‘free–free” support condition was investigated for evaluating the modulus of elasticity (MOE) of full-size wood composite panels (WCPs). Vibration experiments were conducted on three types of WCPs (medium density fibreboard, particleboard, and plywood) to determine the dynamic MOE of the panels. Static...

Developing the elastic modulus measurement of asphalt concrete using the compressive strength test

NASA Astrophysics Data System (ADS)

Setiawan, Arief; Suparma, Latif Budi; Mulyono, Agus Taufik

2017-11-01

Elastic modulus is a fundamental property of an asphalt mixture. An analytical method of the elastic modulus is needed to determine the thickness of flexible pavement. It has a role as one of the input values on a stress-strain analysis in the finite element method. The aim of this study was to develop the measurement of the elastic modulus by using compressive strength testing. This research used a set of specimen mold tool and Delta Dimensi software to record strain changes occurring in the proving ring of compression machine and the specimens. The elastic modulus of the five types of aggregate gradation and 2 types of asphalt were measured at optimum asphalt content. Asphalt Cement 60/70 and Elastomer Modified Asphalt (EMA) were used as a binder. Manufacturing success indicators of the specimens used void-in-the-mix (VIM) 3-5 % criteria. The success rate of the specimen manufacturing was more than 76%. Thus, the procedure and the compressive strength test equipment could be used for the measurement of the elastic modulus. The aggregate gradation and asphalt types significantly affected the elastic modulus of the asphalt concrete.

System importance measures: A new approach to resilient systems-of-systems

NASA Astrophysics Data System (ADS)

Uday, Payuna

Resilience is the ability to withstand and recover rapidly from disruptions. While this attribute has been the focus of research in several fields, in the case of system-of-systems (SoSs), addressing resilience is particularly interesting and challenging. As infrastructure SoSs, such as power, transportation, and communication networks, grow in complexity and interconnectivity, measuring and improving the resilience of these SoSs is vital in terms of safety and providing uninterrupted services. The characteristics of systems-of-systems make analysis and design of resilience challenging. However, these features also offer opportunities to make SoSs resilient using unconventional methods. In this research, we present a new approach to the process of resilience design. The core idea behind the proposed design process is a set of system importance measures (SIMs) that identify systems crucial to overall resilience. Using the results from the SIMs, we determine appropriate strategies from a list of design principles to improve SoS resilience. The main contribution of this research is the development of an aid to design that provides specific guidance on where and how resources need to be targeted. Based on the needs of an SoS, decision-makers can iterate through the design process to identify a set of practical and effective design improvements. We use two case studies to demonstrate how the SIM-based design process can inform decision-making in the context of SoS resilience. The first case study focuses on a naval warfare SoS and describes how the resilience framework can leverage existing simulation models to support end-to-end design. We proceed through stages of the design approach using an agent-based model (ABM) that enables us to demonstrate how simulation tools and analytical models help determine the necessary inputs for the design process and, subsequently, inform decision-making regarding SoS resilience. The second case study considers the urban transportation network in Boston. This case study focuses on interpreting the results of the resilience framework and on describing how they can be used to guide design choices in large infrastructure networks. We use different resilience maps to highlight the range of design-related information that can be obtained from the framework. Specific advantages of the SIM-based resilience design include: (1) incorporates SoS- specific features within existing risk-based design processes - the SIMs determine the relative importance of different systems based on their impacts on SoS-level performance, and suggestions for resilience improvement draw from design options that leverage SoS- specific characteristics, such as the ability to adapt quickly (such as add new systems or re-task existing ones) and to provide partial recovery of performance in the aftermath of a disruption; (2) allows rapid understanding of different areas of concern within the SoS - the visual nature of the resilience map (a key outcome of the SIM analysis) provides a useful way to summarize the current resilience of the SoS as well as point to key systems of concern; and (3) provides a platform for multiple analysts and decision- makers to study, modify, discuss and document options for SoS.

Resilient and Corrosion-Proof Rolling Element Bearings Made from Superelastic Ni-Ti Alloys for Aerospace

NASA Technical Reports Server (NTRS)

Dellacorte, Christopher

2014-01-01

Mechanical components (bearings, gears, mechanisms) typically utilize hardened construction materials to minimize wear and attain long life. In such components, loaded contact points (e.g., meshing gear teeth, bearing balls-raceway contacts) experience high contact stresses. The combination of high hardness and high elastic modulus often leads to damaging contact stress and denting, particularly during transient overload events such as shock impacts that occur during the launching of space vehicles or the landing of aircraft. In this webinar, Dr. DellaCorte will introduce the results of a research project that employs a superelastic alloy, Ni-Ti for rolling element bearing applications. Bearings and components made from such alloys can alleviate many problems encountered in advanced aerospace applications and may solve many terrestrial applications as well

Calculations of Young's moduli for cellulose Iß

USDA-ARS?s Scientific Manuscript database

Young's modulus is a measure of a material’s resistance to deformation as the material is forced to elongate. Modulus values for cotton can be determined by performing tension tests experiments on cotton fibers or, as in this study, by stretching molecular models in a computer program. However, repo...

Southern pine veneer laminates at various moduli of elasticity

Treesearch

George E. Woodson

1972-01-01

Modulus of rigidity (GLT) of veneer laminates was shown to be unrelated to dynamic modulus of elasticity (Ed) of single veneers and also, within the range of samples tested, unrelated to specific gravity. Values determined by flexure test (GLR) were consistent with those from standard plate shear...

Measuring Resilience in the Adolescent Population: A Succinct Tool for Outpatient Adolescent Health.

PubMed

Barger, Jordan; Vitale, Patty; Gaughan, John P; Feldman-Winter, Lori

2017-10-01

To create a valid tool to measure adolescent resilience, and to determine if this tool correlates with current participation in risk behaviors and prior adverse childhood events. One hundred adolescents were recruited from primary care clinics in New Jersey for this cross-sectional study. A "7Cs tool" was developed to measure resilience using the 7Cs model of resilience. All participants completed the 7Cs tool, the Adverse Childhood Events Survey, and the Health Survey for Adolescents to identify current risk behaviors. Demographic and background data were also collected. To assess the validity of the 7Cs tool, Cronbach alpha, principal factor analysis, Spearman coefficients, and sensitivity analyses were conducted. The χ 2 test and ORs were used to determine if any relationships exist between resilience and prior adverse childhood events and risk taking behaviors. Participants ranged from 13 to 21 years old (65% female). Internal consistency was established using Cronbach alpha (0.7). Lower resilience correlated with higher adverse childhood events (P = .008) and Health Survey for Adolescents scores (P < .001). Lower resilience was associated with increased problems in school (OR 2.6; P = .021), drug use (OR 4.0; P = .004), violent behavior (OR 3.7; P = .002), recent depression (OR 5.0; P < .001), and suicidality (OR 4.1; P = .009). Higher resilience was associated with participation in exercise (P = .001) and activities (P = .01). The 7Cs tool is an internally validated tool that may be used to screen adolescent resilience and guide pediatricians' counseling against risk behaviors. Further studies will evaluate resilience-building interventions based on results from this study. Copyright © 2017 Elsevier Inc. All rights reserved.

Coastal wetlands, sea level, and the dimensions of geomorphic resilience

NASA Astrophysics Data System (ADS)

Phillips, Jonathan D.

2018-03-01

Geomorphic system resilience is often perceived as an intrinsic property of system structure and interactions but is also related to idiosyncratic place and history factors. The importance of geographical and historical circumstances makes it difficult to generate categorical statements about geomorphic resilience. However, network-based analyses of system structure can be used to determine the dynamical stability (= resilience) based on generally applicable relationships and to determine scenarios of stability or instability. These provide guidelines for assessing place and history factors to assess resilience. A model of coastal wetlands is analyzed, based on interactions among relative sea level, wetland surface elevation, hydroperiod, vegetation, and sedimentation. The system is generally (but not always) dynamically unstable and non-resilient. Because of gradients of environmental factors and patchy distributions of microtopography and vegetation, a coastal wetland landscape may have extensive local variations in stability/resilience and in the key relationships that trigger instabilities. This is illustrated by a case study where dynamically unstable fragmentation is found in two nearby coastal wetlands in North Carolina's Neuse River estuary-Otter Creek Mouth and Anderson Creek. Neither is keeping pace with relative sea level rise, and both show unstable state transitions within the wetland system; but locally stable relationships exist within the wetland systems.

Annual Research Review: Resilient functioning in maltreated children: Past, present, and future perspectives

PubMed Central

Cicchetti, Dante

2012-01-01

Through a process of probabilistic epigenesis, child maltreatment progressively contributes to compromised adaptation on a variety of developmental domains central to successful adjustment. These developmental failures pose significant risk for the emergence of psychopathology across the life course. In addition to the psychological consequences of maltreatment, a growing body of research has documented the deleterious effects of abuse and neglect on biological processes. Nonetheless, not all maltreated children develop maladaptively. Indeed, some percentage of maltreated children develop in a resilient fashion despite the significant adversity and stress they experience. The literature on the determinants of resilience in maltreated children is selectively reviewed and criteria for the inclusion of the studies are delineated. The majority of the research on the contributors to resilient functioning has focused on a single level of analysis and on psychosocial processes. Multilevel investigations have begun to appear, resulting in several studies on the processes to resilient functioning that integrate biological/genetic and psychological domains. Much additional research on the determinants of resilient functioning must be completed before we possess adequate knowledge based on a multiple levels of analysis approach that is commensurate with the complexity inherent in this dynamic developmental process. Suggestions for future research on the development of resilient functioning in maltreated children are proffered and intervention implications are discussed. PMID:22928717

Response diversity can increase ecological resilience to disturbance in coral reefs.

PubMed

Baskett, Marissa L; Fabina, Nicholas S; Gross, Kevin

2014-08-01

Community-level resilience depends on the interaction between multiple populations that vary in individual responses to disturbance. For example, in tropical reefs, some corals can survive higher stress (resistance) while others exhibit faster recovery (engineering resilience) following disturbances such as thermal stress. While each type will negatively affect the other through competition, each might also benefit the other by reducing the potential for an additional competitor such as macroalgae to invade after a disturbance. To determine how community composition affects ecological resilience, we modeled coral-macroalgae interactions given either a resistant coral, a resilient coral, or both together. Having both coral types (i.e., response diversity) can lead to observable enhanced ecological resilience if (1) the resilient coral is not a superior competitor and (2) disturbance levels are high enough such that the resilient coral would collapse when considered alone. This enhanced resilience occurs through competitor-enabled rescue where each coral increases the potential for the other to recover from disturbance through external recruitment, such that both corals benefit from the presence of each other in terms of total cover and resilience. Therefore, conservation management aimed at protecting resilience under global change requires consideration of both diversity and connectivity between sites experiencing differential disturbance.

Community Resilience of Civilians at War: A New Perspective.

PubMed

Eshel, Yohanan; Kimhi, Shaul

2016-01-01

A new concept of community resilience pertaining to the community's post adversity strength to vulnerability ratio was associated with five determinants: individual resilience, national resilience, well-being, community size, and sense of coherence. The data was collected four months after Israel's war in the Gaza Strip in 2014. Participants were 251 adult civilians living in southern Israel who have recently been threatened by massive missile attacks, and 259 adults living in northern Israel, which has not been under missile fire recently. The investigated variables predicted community resilience, and their effects were mediated by sense of coherence. Results which were similar for both samples were discussed in terms of the nature of resilience and in terms of proximal and distal exposure to war.

The Relationship between Adverse Childhood Events, Resiliency and Health among Children with Autism

ERIC Educational Resources Information Center

Rigles, Bethany

2017-01-01

Previous research has shown a negative relationship between adverse childhood events (ACEs) and health and resiliency among the general population, but has not examined these associations among children with autism. Purpose: To determine the prevalence of ACEs among children with autism and how ACEs are associated with resiliency and health.…

Profiles of Personal Resiliency in Youth Who Have Experienced Physical or Sexual Abuse

ERIC Educational Resources Information Center

Deblinger, Esther; Runyon, Melissa K.; Steer, Robert A.

2014-01-01

To determine whether children and adolescents (7-17 years old) who had experienced physical, sexual, or both types of abuse reflected distinct profiles of personal resiliency, we administered the "Resiliency Scales for Children and Adolescents" (RSCA) to 250 youth. We performed cluster analyses with T scores for the RSCA Self-Mastery,…

Measuring the Rebound Resilience of a Bouncing Ball

ERIC Educational Resources Information Center

Wadhwa, Ajay

2012-01-01

Some balls which are made of high-quality rubber (an elastomeric) material, such as tennis or squash balls, could be used for the determination of an important property of such materials called resilience. Since a bouncing ball involves a single impact we call this property "rebound resilience" and express it as the ratio of the rebound height to…

The Relation between Pre-Service Music Teachers' Psychological Resilience and Academic Achievement Levels

ERIC Educational Resources Information Center

Yokus, Tuba

2015-01-01

This study aims to examine the relation between pre-service music teachers' psychological resilience and academic achievement levels and to determine what variables influence their psychological resilience levels. The study sample consisted of students enrolled in a music education program in the 2013-2014 academic year (N = 333). In respect with…

Investigation of High School Students' Resiliency Perception in Terms of Some Variables

ERIC Educational Resources Information Center

Arastaman, Gokhan; Balci, Ali

2013-01-01

The purpose of this study is to examine the resilience of high school students in Turkey, and to determine the relationships between the student resiliency and some protective factors such as school climate, teacher attitudes and behaviors, family and peer support according to the student opinions. By using 509 students randomly selected from 24…

Composite elastomeric polyurethane scaffolds incorporating small intestinal submucosa for soft tissue engineering.

PubMed

Da, Lincui; Gong, Mei; Chen, Anjing; Zhang, Yi; Huang, Yizhou; Guo, Zhijun; Li, Shengfu; Li-Ling, Jesse; Zhang, Li; Xie, Huiqi

2017-09-01

Although soft tissue replacement has been clinically successful in many cases, the corresponding procedure has many limitations including the lack of resilience and mechanical integrity, significant donor-site morbidity, volume loss with time, and fibrous capsular contracture. These disadvantages can be alleviated by utilizing bio-absorbable scaffolds with high resilience and large strain, which are capable of stimulating natural tissue regeneration. Hence, the chemically crosslinked tridimensional scaffolds obtained by incorporating water-based polyurethane (PU) (which was synthesized from polytetramethylene ether glycol, isophorone diisocyanate, and 2,2-bis(hydroxymethyl) butyric acid) into a bioactive extracellular matrix consisting of small intestinal submucosa (SIS) have been tested in this study to develop a new approach for soft tissue engineering. After characterizing the structure and properties of the produced PU/SIS composites, the strength, Young's modulus, and resilience of wet PU/SIS samples were compared with those of crosslinked PU. In addition, the fabricated specimens were investigated using human umbilical vein endothelial cells to evaluate their ability to enhance cell attachment and proliferation. As a result, the synthesized PU/SIS samples exhibited high resilience and were capable of enhancing cell viability with no evidence of cytotoxicity. Subcutaneous implantation in animals and the subsequent testing conducted after 2, 4, and 8weeks indicated that sound implant integration and vascularization occurred inside the PU/SIS composites, while the presence of SIS promoted cell infiltration, angiogenesis, and ultimately tissue regeneration. The obtained results revealed that the produced PU/SIS composites were characterized by high bioactivity and resilience, and, therefore, could be used for soft tissue engineering applications. Hybrid composites containing synthetic polymers with high mechanical strength and naturally derived components, which create a bio-mimetic environment, are one of the most promising biomaterials. Although synthetic polymer/ECM composites have been previously used for soft tissue repair, their resilience properties were not investigated in sufficient detail, while the development of elastic composites composed of synthetic polymers and ECMs in nontoxic aqueous solutions remains a rather challenging task. In this study, porous PU/SIS composites were fabricated in a non-toxic manner; the obtained materials exhibited sufficient mechanical support, which promote cell growth, angiogenesis, and tissue regeneration. The described method can be adapted for the development of scaffolds with various acellular matrices and subsequently used during the restoration of particular types of tissue. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Racial Discrimination, Cultural Resilience, and Stress.

PubMed

Spence, Nicholas D; Wells, Samantha; Graham, Kathryn; George, Julie

2016-05-01

Racial discrimination is a social determinant of health for First Nations people. Cultural resilience has been regarded as a potentially positive resource for social outcomes. Using a compensatory model of resilience, this study sought to determine if cultural resilience (compensatory factor) neutralized or offset the detrimental effect of racial discrimination (social risk factor) on stress (outcome). Data were collected from October 2012 to February 2013 (N = 340) from adult members of the Kettle and Stony Point First Nation community in Ontario, Canada. The outcome was perceived stress; risk factor, racial discrimination; and compensatory factor, cultural resilience. Control variables included individual (education, sociability) and family (marital status, socioeconomic status) resilience resources and demographics (age and gender). The model was tested using sequential regression. The risk factor, racial discrimination, increased stress across steps of the sequential model, while cultural resilience had an opposite modest effect on stress levels. In the final model with all variables, age and gender were significant, with the former having a negative effect on stress and women reporting higher levels of stress than males. Education, marital status, and socioeconomic status (household income) were not significant in the model. The model had R(2) = 0.21 and adjusted R(2) = 0.18 and semipartial correlation (squared) of 0.04 and 0.01 for racial discrimination and cultural resilience, respectively. In this study, cultural resilience compensated for the detrimental effect of racial discrimination on stress in a modest manner. These findings may support the development of programs and services fostering First Nations culture, pending further study. © The Author(s) 2016.

Racial Discrimination, Cultural Resilience, and Stress

PubMed Central

Wells, Samantha; Graham, Kathryn; George, Julie

2016-01-01

Objective: Racial discrimination is a social determinant of health for First Nations people. Cultural resilience has been regarded as a potentially positive resource for social outcomes. Using a compensatory model of resilience, this study sought to determine if cultural resilience (compensatory factor) neutralized or offset the detrimental effect of racial discrimination (social risk factor) on stress (outcome). Methods: Data were collected from October 2012 to February 2013 (N = 340) from adult members of the Kettle and Stony Point First Nation community in Ontario, Canada. The outcome was perceived stress; risk factor, racial discrimination; and compensatory factor, cultural resilience. Control variables included individual (education, sociability) and family (marital status, socioeconomic status) resilience resources and demographics (age and gender). The model was tested using sequential regression. Results: The risk factor, racial discrimination, increased stress across steps of the sequential model, while cultural resilience had an opposite modest effect on stress levels. In the final model with all variables, age and gender were significant, with the former having a negative effect on stress and women reporting higher levels of stress than males. Education, marital status, and socioeconomic status (household income) were not significant in the model. The model had R2 = 0.21 and adjusted R2 = 0.18 and semipartial correlation (squared) of 0.04 and 0.01 for racial discrimination and cultural resilience, respectively. Conclusions: In this study, cultural resilience compensated for the detrimental effect of racial discrimination on stress in a modest manner. These findings may support the development of programs and services fostering First Nations culture, pending further study. PMID:27254805

A novel method to determine the elastic modulus of extremely soft materials.

PubMed

Stirling, Tamás; Zrínyi, Miklós

2015-06-07

Determination of the elastic moduli of extremely soft materials that may deform under their own weight is a rather difficult experimental task. A new method has been elaborated by means of which the elastic modulus of such materials can be determined. This method is generally applicable to all soft materials with purely neo-Hookean elastic deformation behaviour with elastic moduli lower than 1 kPa. Our novel method utilises the self-deformation of pendent gel cylinders under gravity. When suspended, the material at the very top bears the weight of the entire gel cylinder, but that at the bottom carries no load at all. Due to the non-uniform stress distribution along the gel sample both the stress and the resulting strain show position dependence. The cross-sectional area of the material is lowest at the top of the sample and gradually increases towards its bottom. The equilibrium geometry of the pendant gel is used to evaluate the elastic modulus. Experimental data obtained by the proposed new method were compared to the results obtained from underwater measurements. The parameters affecting the measurement uncertainty were studied by a Pareto analysis of a series of adaptive Monte Carlo simulations. It has been shown that our method provides an easily achievable method to provide an accurate determination of the elastic modulus of extremely soft matter typically applicable for moduli below 1 kPa.

Coexistence and different determinants of posttraumatic stress disorder and posttraumatic growth among Chinese survivors after earthquake: role of resilience and rumination.

PubMed

Wu, Kaijun; Zhang, Yuqing; Liu, Zhengkui; Zhou, Peiling; Wei, Chuguang

2015-01-01

Posttraumatic stress disorder (PTSD) and posttraumatic growth (PTG) are two different outcomes that may occur after experiencing traumatic events. Resilience and rumination are two important factors that determine the development of these outcomes after trauma. We investigated the association between these two factors, PTSD and PTG, among Chinese survivors in an earthquake. With a convenience sample of 318 survivors from earthquake, we measured trauma exposure, PTSD, PTG, resilience, and rumination (Impact of Event Scale-Revised, Posttraumatic Growth Inventory, 10 item Connor-Davidson Resilience Scale, Ruminative Response Scale). Then we used bivariate correlation and structural equation modeling to examine the structure of relations among these factors. Results showed that resilience and reflective rumination have a positive effect on PTG (β = 0.32, p < 0.001; β = 0.17, p = 0.049). Earthquake exposure, brooding rumination and depressed-related rumination are related with higher level of PTSD (β = 0.10, p = 0.021; β = 0.33, p < 0.001; β = 0.36, p < 0.001). The findings suggest distinct determinants of the negative and positive outcomes, and this may provide better understanding about the risk and protective factors for traumatic reactions.

Mechanical properties of novel forms of graphyne under strain: A density functional theory study

NASA Astrophysics Data System (ADS)

Majidi, Roya

2017-06-01

The mechanical properties of two forms of graphyne sheets named α-graphyne and α2-graphyne under uniaxial and biaxial strains were studied. In-plane stiffness, bulk modulus, and shear modulus were calculated based on density functional theory. The in-plane stiffness, bulk modulus, and shear modulus of α2-graphyne were found to be larger than that of α-graphyne. The maximum values of supported uniaxial and biaxial strains before failure were determined. The α-graphyne was entered into the plastic region with the higher magnitude of tension in comparison to α2-graphyne. The mechanical properties of α-graphyne family revealed that these forms of graphyne are proper materials for use in nanomechanical applications.

Determination of Young's modulus of epoxy coated polyethylene micro-cantilever using phase-shift shadow moiré method

NASA Astrophysics Data System (ADS)

Lim, J. H.; Ratnam, M. M.; Azid, I. A.; Mutharasu, D.

2011-11-01

Young's moduli of various epoxy coated polyethylene terephthalate (PET) micro-cantilevers were determined from the deflection results obtained using the phase-shift shadow moiré (PSSM) method. The filler materials for epoxy coatings were aluminum and graphite powders that were mixed with epoxy at various percentages. Young's moduli were calculated from theory based on the deflection results. The PET micro-cantilever coated with aluminum-epoxy coating showed increasing value of Young's modulus when the ratios of the aluminum-epoxy were increased. The graphite-epoxy coating on the PET micro-cantilever also showed the same trend. The experimental results also show that Young's modulus of the graphite-epoxy coating is higher than aluminum-epoxy coating in comparison at the same mixing ratio.

[Profiles of resilience and quality of life in people with acquired disability due to traffic accidents].

PubMed

Suriá Martínez, Raquel

2015-09-01

To identify distinct profiles of resilience in people with spinal cord injuries due to traffic accidents and to determine whether the profiles identified are related to differences in subjective well-being. The Resilience Scale (Wagnild and Young, 1993) and an adapted quality of life scale (GENCAT) were administered to 98 people with physical disabilities due to traffic accidents. Cluster analyses identified three different resilience profiles: a high-resilience group, a low-resilience group, and a group showing a predominance of high scores in self and life acceptance and social competence. The results also revealed statistically significant differences among profiles in most domains of subjective well-being. The results suggest the need to study resilience in greater depth and to design programs to enhance quality of life among people with disabilities due to traffic accidents. Copyright © 2014 SESPAS. Published by Elsevier Espana. All rights reserved.

Determining Young's Modulus by Measuring Guitar String Frequency

ERIC Educational Resources Information Center

Polak, Robert D.; Davenport, Adam R. V.; Fischer, Andrew; Rafferty, Jared

2018-01-01

Values for physical constants are commonly given as abstractions without building strong intuition, and are too often utilized solely in the pursuit of more easily conceptualized properties. The goal of this experiment is to remove the obscurity behind Young's modulus by exploring the phenomena associated with it--namely, the frequency of a…

Relationship between radial compressive modulus of elasticity and shear modulus of wood

Treesearch

Jen Y. Liu; Robert J. Ross

2005-01-01

Wood properties in transverse compression are difficult to determine because of such factors as anatomical complexity, specimen geometry, and loading conditions. The mechanical properties of wood, considered as an anisotropic or orthotropic material, are related by certain tensor transformation rules when the reference coordinate system changes its orientation. In this...

Effects of silvicultural practice and moisture content level on lobolly pine veneer mechanical properties

Treesearch

Todd F. Shupe; Chung-Yun Hse; Elvin T. Choong; Leslie H. Groom

1998-01-01

Loblolly pine veneer specimens were obtained from five silviculturally different stands. Clear specimens were cut parallel to the grain from full size veneer sheets and tests were done at either air-dry or ovendry conditions to determine differences in bending modulus of rupture (MORb), bending modulus of elasticity (MOEb...

Determination of Material Properties Near the Glass Transition Temperature for an Isogrid Boom

NASA Technical Reports Server (NTRS)

Blandino, Joseph R.; Woods-Vedeler, Jessica A. (Technical Monitor)

2002-01-01

Experiments were performed and results obtained to determine the temperature dependence of the modulus of elasticity for a thermoplastic isogrid tube. The isogrid tube was subjected to axial tensile loads of 0-100 lbf and strain was measured at room and elevated temperatures of 100, 120, 140, 160, 180, 190, and 200 F. These were based on tube manufacturer specifying an incorrect glass transition temperature of 210 F. Two protocols were used. For the first protocol the tube was brought to temperature and a tensile test performed. The tube was allowed to cool between tests. For the second protocol the tube was ramped to the desired test temperature and held. A tensile test was performed and the tube temperature ramped to the next test temperature. The second protocol spanned the entire test range. The strain rate was constant at 0.008 in/min. Room temperature tests resulted in the determination of an average modulus of 2.34 x 106 Psi. The modulus decreased above 100 F. At 140 F the modulus had decreased by 7.26%. The two test protocols showed good agreement below 160 F. At this point the glass transition temperature had been exceeded. The two protocols were not repeated because the tube failed.

Development and Validation of a Brief Measure of Psychological Resilience: An Adaptation of the Response to Stressful Experiences Scale.

PubMed

De La Rosa, Gabriel M; Webb-Murphy, Jennifer A; Johnston, Scott L

2016-03-01

Resilience helps determine how people respond to stress. The Response to Stressful Events Scale (RSES) is an existing 22-item measure of resilience. We investigate the psychometric properties of the RSES and develop a 4-item measure of resilience using the most discriminating items from the RSES. Among two samples of military personnel presenting to mental health clinics, we see that the abbreviated resilience measure displays comparable internal consistency and test-retest reliability (versus the existing RSES). Among a sample of deployed military personnel, the abbreviated scale relates to validated measures of psychological strain. The 4-item abbreviated RSES measure is a brief, reliable, and valid measure of resilience. Reprint & Copyright © 2016 Association of Military Surgeons of the U.S.

Burnout and health among critical care professionals: The mediational role of resilience.

PubMed

Arrogante, Oscar; Aparicio-Zaldivar, Eva

2017-10-01

To analyse the mediational role of resilience in relationships between burnout and health in critical care professionals; to determine relationships among resilience level, three burnout dimensions, and physical/mental health; and to establish demographic differences in psychological variables evaluated. Cross-sectional study. A total of 52 critical care professionals, mainly nurses, were recruited from an intensive care unit of Madrid (Spain). All participants were assessed with the questionnaires 10-item Connor-Davidson Resilience Scale, Maslach Burnout Inventory-Human Services Survey, and Short Form-12 Health Survey. No demographic differences were found. Three burnout dimensions were negatively associated with mental health and resilience. Mediational analyses revealed resilience mediated 1) the relationships between emotional exhaustion and depersonalisation with mental health (partial mediations) and 2) the relationship between personal accomplishment and mental health (total mediation). Resilience minimises and buffers the impact of negative outcomes of workplace stress on mental health of critical care professionals. As a result, resilience prevents the occurrence of burnout syndrome. Resilience improves not only their mental health, but also their ability to practice effectively. It is therefore imperative to develop resilience programs for critical care nurses in nursing schools, universities and health centres. Copyright © 2017 Elsevier Ltd. All rights reserved.

Exploring the resilience of industrial ecosystems.

PubMed

Zhu, Junming; Ruth, Matthias

2013-06-15

Industrial ecosystems improve eco-efficiency at the system level through optimizing material and energy flows, which however raises a concern for system resilience because efficiency, as traditionally conceived, not necessarily promotes resilience. By drawing on the concept of resilience in ecological systems and in supply chains, resilience in industrial ecosystems is specified on the basis of a system's ability to maintain eco-efficient material and energy flows under disruptions. Using a network model that captures supply, asset, and organizational dependencies and propagation of disruptions among firms, the resilience, and particularly resistance as an important dimension of resilience, of two real industrial ecosystems and generalized specifications are examined. The results show that an industrial ecosystem is less resistant and less resilient with high inter-firm dependency, preferentially organized physical exchanges, and under disruptions targeted at highly connected firms. An industrial ecosystem with more firms and exchanges is less resistant, but has more eco-efficient flows and potentials, and therefore is less likely to lose its function of eco-efficiency. Taking these determinants for resilience into consideration improves the adaptability of an industrial ecosystem, which helps increase its resilience. Copyright © 2013 Elsevier Ltd. All rights reserved.

Propellant grain dynamics in aft attach ring of shuttle solid rocket booster

NASA Technical Reports Server (NTRS)

Verderaime, V.

1979-01-01

An analytical technique for implementing simultaneously the temperature, dynamic strain, real modulus, and frequency properties of solid propellant in an unsymmetrical vibrating ring mode is presented. All dynamic parameters and sources are defined for a free vibrating ring-grain structure with initial displacement and related to a forced vibrating system to determine the change in real modulus. Propellant test data application is discussed. The technique was developed to determine the aft attach ring stiffness of the shuttle booster at lift-off.

Dynamic modulus estimation and structural vibration analysis.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gupta, A.

1998-11-18

Often the dynamic elastic modulus of a material with frequency dependent properties is difficult to estimate. These uncertainties are compounded in any structural vibration analysis using the material properties. Here, different experimental techniques are used to estimate the properties of a particular elastomeric material over a broad frequency range. Once the properties are determined, various structures incorporating the elastomer are analyzed by an interactive finite element method to determine natural frequencies and mode shapes. Then, the finite element results are correlated with results obtained by experimental modal analysis.

Resilience following spinal cord injury: A prospective controlled study investigating the influence of the provision of group cognitive behavior therapy during inpatient rehabilitation.

PubMed

Guest, Rebecca; Craig, Ashley; Nicholson Perry, Kathryn; Tran, Yvonne; Ephraums, Catherine; Hales, Alison; Dezarnaulds, Annalisa; Crino, Rocco; Middleton, James

2015-11-01

To examine change in resilience in people with spinal cord injury (SCI) when group cognitive behavior therapy (GCBT) was added to routine psychosocial rehabilitation (RPR). A prospective repeated-measures cohort design was used to determine the efficacy of the addition of GCBT (n = 50). The control group consisted of individuals receiving RPR, which included access to individual CBT (ICBT) when required (n = 38). Groups were assessed on 3 occasions: soon after admission, within 2 weeks of discharge, and 6-months postdischarge. Measures included sociodemographic, injury, and psychosocial factors. The outcome variable was resilience, considered an important outcome measure for recovery. To adjust for baseline differences in self-efficacy, depressive mood and anxiety between the 2 groups, these factors were entered into a repeated measures multivariate analysis of covariance (MANCOVA) as covariates. Latent class analysis was used to determine the best-fitting model of resilience trajectories for both groups. The MANCOVA indicated that the addition of GCBT to psychosocial rehabilitation did not result in improved resilience compared with the ICBT group. Trajectory data indicated over 60% were demonstrating acceptable resilience irrespective of group. Changes in resilience mean scores suggest the addition of GCBT adds little to resilience outcomes. Latent class modeling indicated both groups experienced similar trajectories of improvement and deterioration. Results highlight the importance of conducting multivariate modeling analysis that isolates subgroups of related cases over time to understand complex trajectories. Further research is needed to clarify individual differences in CBT intervention preference as well as other factors which impact on resilience. (c) 2015 APA, all rights reserved).

Can We Predict Burnout among Student Nurses? An Exploration of the ICWR-1 Model of Individual Psychological Resilience

PubMed Central

Rees, Clare S.; Heritage, Brody; Osseiran-Moisson, Rebecca; Chamberlain, Diane; Cusack, Lynette; Anderson, Judith; Terry, Victoria; Rogers, Cath; Hemsworth, David; Cross, Wendy; Hegney, Desley G.

2016-01-01

The nature of nursing work is demanding and can be stressful. Previous studies have shown a high rate of burnout among employed nurses. Recently, efforts have been made to understand the role of resilience in determining the psychological adjustment of employed nurses. A theoretical model of resilience was proposed recently that includes several constructs identified in the literature related to resilience and to psychological functioning. As nursing students are the future of the nursing workforce it is important to advance our understanding of the determinants of resilience in this population. Student nurses who had completed their final practicum were invited to participate in an online survey measuring the key constructs of the ICWR-1 model. 422 students from across Australia and Canada completed the survey between July 2014 and July 2015. As well as several key demographics, trait negative affect, mindfulness, self-efficacy, coping, resilience, and burnout were measured. We used structural equation modeling and found support for the major pathways of the model; namely that resilience had a significant influence on the relationship between mindfulness, self-efficacy and coping, and psychological adjustment (burnout scores). Furthermore, as predicted, Neuroticism moderated the relationship between coping and burnout. Results are discussed in terms of potential approaches to supporting nursing students who may be at risk of burnout. PMID:27486419

Can We Predict Burnout among Student Nurses? An Exploration of the ICWR-1 Model of Individual Psychological Resilience.

PubMed

Rees, Clare S; Heritage, Brody; Osseiran-Moisson, Rebecca; Chamberlain, Diane; Cusack, Lynette; Anderson, Judith; Terry, Victoria; Rogers, Cath; Hemsworth, David; Cross, Wendy; Hegney, Desley G

2016-01-01

The nature of nursing work is demanding and can be stressful. Previous studies have shown a high rate of burnout among employed nurses. Recently, efforts have been made to understand the role of resilience in determining the psychological adjustment of employed nurses. A theoretical model of resilience was proposed recently that includes several constructs identified in the literature related to resilience and to psychological functioning. As nursing students are the future of the nursing workforce it is important to advance our understanding of the determinants of resilience in this population. Student nurses who had completed their final practicum were invited to participate in an online survey measuring the key constructs of the ICWR-1 model. 422 students from across Australia and Canada completed the survey between July 2014 and July 2015. As well as several key demographics, trait negative affect, mindfulness, self-efficacy, coping, resilience, and burnout were measured. We used structural equation modeling and found support for the major pathways of the model; namely that resilience had a significant influence on the relationship between mindfulness, self-efficacy and coping, and psychological adjustment (burnout scores). Furthermore, as predicted, Neuroticism moderated the relationship between coping and burnout. Results are discussed in terms of potential approaches to supporting nursing students who may be at risk of burnout.

Study to determine and analyze the strength of high modulus glass in epoxy-matrix composites

NASA Technical Reports Server (NTRS)

Bacon, J. F.

1974-01-01

Glass composition research was conducted to produce a high modulus, high strength beryllium-free glass fiber. This program was built on the previous research for developing high modulus, high strength glass fibers which had a 5 weight percent beryllia content. The fibers resulting from the composition program were then used to produce fiber reinforced-epoxy resin composites which were compared with composites reinforced by commercial high modulus glass fibers, Thornel S graphite fiber, and hybrids where the external quarters were reinforced with Thornel S graphite fiber and the interior half with glass fiber as well as the reverse hybrid. The composites were given tensile strength, compressive strength, short-beam shear strength, creep and fatigue tests. Comments are included on the significance of the test data.

A Finite Element Model to Predict the Effect of Porosity on Elastic Modulus in Low-Porosity Materials

NASA Astrophysics Data System (ADS)

Morrissey, Liam S.; Nakhla, Sam

2018-07-01

The effect of porosity on elastic modulus in low-porosity materials is investigated. First, several models used to predict the reduction in elastic modulus due to porosity are compared with a compilation of experimental data to determine their ranges of validity and accuracy. The overlapping solid spheres model is found to be most accurate with the experimental data and valid between 3 and 10 pct porosity. Next, a FEM is developed with the objective of demonstrating that a macroscale plate with a center hole can be used to model the effect of microscale porosity on elastic modulus. The FEM agrees best with the overlapping solid spheres model and shows higher accuracy with experimental data than the overlapping solid spheres model.

Mechanical properties of carbon nanotubes

NASA Astrophysics Data System (ADS)

Salvetat, J.-P.; Bonard, J.-M.; Thomson, N. H.; Kulik, A. J.; Forró, L.; Benoit, W.; Zuppiroli, L.

A variety of outstanding experimental results on the elucidation of the elastic properties of carbon nanotubes are fast appearing. These are based mainly on the techniques of high-resolution transmission electron microscopy (HRTEM) and atomic force microscopy (AFM) to determine the Young's moduli of single-wall nanotube bundles and multi-walled nanotubes, prepared by a number of methods. These results are confirming the theoretical predictions that carbon nanotubes have high strength plus extraordinary flexibility and resilience. As well as summarising the most notable achievements of theory and experiment in the last few years, this paper explains the properties of nanotubes in the wider context of materials science and highlights the contribution of our research group in this rapidly expanding field. A deeper understanding of the relationship between the structural order of the nanotubes and their mechanical properties will be necessary for the development of carbon-nanotube-based composites. Our research to date illustrates a qualitative relationship between the Young's modulus of a nanotube and the amount of disorder in the atomic structure of the walls. Other exciting results indicate that composites will benefit from the exceptional mechanical properties of carbon nanotubes, but that the major outstanding problem of load transfer efficiency must be overcome before suitable engineering materials can be produced.

The study of stiffness modulus values for AC-WC pavement

NASA Astrophysics Data System (ADS)

Lubis, AS; Muis, Z. A.; Iskandar, T. D.

2018-02-01

One of the parameters of the asphalt mixture in order for the strength and durability to be achieved as required is the stress-and-strain showing the stiffness of a material. Stiffness modulus is a very necessary factor that will affect the performance of asphalt pavements. If the stiffness modulus value decreases there will be a cause of aging asphalt pavement crack easily when receiving a heavy load. The high stiffness modulus asphalt concrete causes more stiff and resistant to bending. The stiffness modulus value of an asphalt mixture material can be obtained from the theoretical (indirect methods) and laboratory test results (direct methods). For the indirect methods used Brown & Brunton method, and Shell Bitumen method; while for the direct methods used the UMATTA tool. This study aims to determine stiffness modulus values for AC-WC pavement. The tests were conducted in laboratory that used 3 methods, i.e. Brown & Brunton Method, Shell Bitumen Method and Marshall Test as a substitute tool for the UMATTA tool. Hotmix asphalt made from type AC-WC with pen 60/70 using a mixture of optimum bitumen content was 5.84% with a standard temperature variation was 60°C and several variations of temperature that were 30, 40, 50, 70 and 80°C. The stiffness modulus value results obtained from Brown & Brunton Method, Shell Bitumen Method and Marshall Test which were 1374,93 Mpa, 235,45 Mpa dan 254,96 Mpa. The stiffness modulus value decreases with increasing temperature of the concrete asphalt. The stiffness modulus value from the Bitumen Shell method and the Marshall Test has a relatively similar value.The stiffness modulus value from the Brown & Brunton method is greater than the Bitumen Shell method and the Marshall Test, but can not measure the stiffness modulus value at temperature above 80°C.

Young's modulus measurement of aluminum thin film with cantilever structure

NASA Astrophysics Data System (ADS)

Lee, ByoungChan; Lee, SangHun; Lee, Hwasu; Shin, Hyungjae

2001-09-01

Micromachined cantilever structures are commonly used for measuring mechanical properties of thin film materials in MEMS. The application of conventional cantilever theory in experiment raises severe problem. The deformation of the supporting post and flange is produced by the applied electrostatic force and lead to more reduced measurement value than real Young's modulus of thin film materials. In order to determine Young's modulus of aluminum thin film robustly and reproducibly, the modified cantilever structure is proposed. Two measurement methods, which are cantilever tip deflection measurement and resonant frequency measurement, are used for confirming the reliability of the proposed cantilever structure as well. Measured results indicate that the proposed measurement scheme provides useful and credible Young's modulus value for thin film materials with sub-micron thickness. The proved validation of the proposed scheme makes sure that in addition to Young's modulus of aluminum thin film, that of other thin film materials which are aluminum alloy, metal, and so forth, can be extracted easily and clearly.

Mechanical properties of composite materials

NASA Technical Reports Server (NTRS)

Thornton, H. Richard; Cornwell, L. R.

1993-01-01

A composite material incorporates high strength, high modulus fibers in a matrix (polymer, metal, or ceramic). The fibers may be oriented in a manner to give varying in-plane properties (longitudinal, transverse-stress, strain, and modulus of elasticity). The lay-up of the composite laminates is such that a center line of symmetry and no bending moment exist through the thickness. The laminates are tabbed, with either aluminum or fiberglass, and are ready for tensile testing. The determination of the tensile properties of resin matrix composites, reinforced by continuous fibers, is outlined in ASTM standard D 3039, Tensile Properties of Oriented Fiber Composites. The tabbed flat tensile coupons are placed into the grips of a tensile machine and load-deformation curves plotted. The load-deformation data are translated into stress-strain curves for determination of mechanical properties (ultimate tensile strength and modulus of elasticity).

Damage of the Interface Between an Orthodontic Bracket and Enamel - the Effect of Some Elastic Properties of the Adhesive Material

NASA Astrophysics Data System (ADS)

Durgesh, B. H.; Alkheraif, A. A.; Al Sharawy, M.; Varrela, J.; Vallittu, P. K.

2016-01-01

The aim of this study was to investigate the magnitude of debonding stress of an orthodontic bracket bonded to the enamel with resin systems having different elastic properties. For the same purpose, sixty human premolars were randomly divided into four groups according to the adhesive system used for bonding brackets: G Fix flowable resin (GFI) with Everstick NET (ESN), GFI, G Aenial Universal Flow (GAU) with ESN, and GAU. The brackets were stressed in the occlusogingival direction on a universal testing machine. The values of debonding load and displacement were determined at the point of debonding. The elastic modulus of the tested materials was determined using nanoindentation. An analysis of variance showed a significant difference in the loads required to debond the bracket among the groups tested. The GAU group had the highest elastic modulus, followed by the GFI and ESN groups. ARI (Adhesive Remnant Index) scores demonstrated more remnants of the adhesive material on the bracket surface with adhesives having a higher elastic modulus. Taking into consideration results of the present in-vitro study, it can be concluded that the incorporation of a glass-fiber-reinforced composite resin (FRC) with a low elastic modulus between the orthodontic bracket and enamel increases the debonding force and strain more than with adhesive systems having a higher elastic modulus.

Confinement Effect on Material Properties of RC Beams Under Flexure

NASA Astrophysics Data System (ADS)

Kulkarni, Sumant; Shiyekar, Mukund Ramchandra; Shiyekar, Sandip Mukund

2017-12-01

In structural analysis, especially in indeterminate structures, it becomes essential to know the material and geometrical properties of members. The codal provisions recommend elastic properties of concrete and steel and these are fairly accurate enough. The stress-strain curve for concrete cylinder or a cube specimen is plotted. The slope of this curve is modulus of elasticity of plain concrete. Another method of determining modulus of elasticity of concrete is by flexural test of a beam specimen. The modulus of elasticity most commonly used for concrete is secant modulus. The modulus of elasticity of steel is obtained by performing a tension test of steel bar. While performing analysis by any software for high rise building, cross area of plain concrete is taken into consideration whereas effects of reinforcement bars and concrete confined by stirrups are neglected. Present aim of study is to determine elastic properties of reinforced cement concrete beam. Two important stiffness properties such as AE and EI play important role in analysis of high rise RCC building idealized as plane frame. The experimental program consists of testing of beams (model size 150 × 150 × 700 mm) with percentage of reinforcement varying from 0.54 to 1.63% which commensurate with existing Codal provisions of IS:456-2000 for flexural member. The effect of confinement is considered in this study. The experimental results are verified by using 3D finite element techniques.

Validity of measurement of shear modulus by ultrasound shear wave elastography in human pennate muscle.

PubMed

Miyamoto, Naokazu; Hirata, Kosuke; Kanehisa, Hiroaki; Yoshitake, Yasuhide

2015-01-01

Ultrasound shear wave elastography is becoming a valuable tool for measuring mechanical properties of individual muscles. Since ultrasound shear wave elastography measures shear modulus along the principal axis of the probe (i.e., along the transverse axis of the imaging plane), the measured shear modulus most accurately represents the mechanical property of the muscle along the fascicle direction when the probe's principal axis is parallel to the fascicle direction in the plane of the ultrasound image. However, it is unclear how the measured shear modulus is affected by the probe angle relative to the fascicle direction in the same plane. The purpose of the present study was therefore to examine whether the angle between the principal axis of the probe and the fascicle direction in the same plane affects the measured shear modulus. Shear modulus in seven specially-designed tissue-mimicking phantoms, and in eleven human in-vivo biceps brachii and medial gastrocnemius were determined by using ultrasound shear wave elastography. The probe was positioned parallel or 20° obliquely to the fascicle across the B-mode images. The reproducibility of shear modulus measurements was high for both parallel and oblique conditions. Although there was a significant effect of the probe angle relative to the fascicle on the shear modulus in human experiment, the magnitude was negligibly small. These findings indicate that the ultrasound shear wave elastography is a valid tool for evaluating the mechanical property of pennate muscles along the fascicle direction.

Elastic Modulus Measurement of ORNL ATF FeCrAl Alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thompson, Zachary T.; Terrani, Kurt A.; Yamamoto, Yukinori

2015-10-01

Elastic modulus and Poisson’s ratio for a number of wrought FeCrAl alloys, intended for accident tolerant fuel cladding application, are determined via resonant ultrasonic spectroscopy. The results are reported as a function of temperature from room temperature to 850°C. The wrought alloys were in the fully annealed and unirradiated state. The elastic modulus for the wrought FeCrAl alloys is at least twice that of Zr-based alloys over the temperature range of this study. The Poisson’s ratio of the alloys was 0.28 on average and increased very slightly with increasing temperature.

Determining shear modulus of thin wood composite materials using a cantilever beam vibration method

Treesearch

Cheng Guan; Houjiang Zhang; John F. Hunt; Haicheng Yan

2016-01-01

Shear modulus (G) of thin wood composite materials is one of several important indicators that characterizes mechanical properties. However, there is not an easy method to obtain this value. This study presents the use of a newly developed cantilever beam free vibration test apparatus to detect in-plane G of thin wood composite...

Modeling of the endosperm crush response profile of hard red spring wheat using a single kernel characterization system

USDA-ARS?s Scientific Manuscript database

When a wheat endosperm is crushed the force profile shows viscoelastic response and the modulus of elasticity is an important parameter that might have substantial influence on wheat milling. An experiment was performed to model endosperm crush response profile (ECRP) and to determine the modulus o...

Elastoplastic properties of a low-modulus titanium-based β alloy

NASA Astrophysics Data System (ADS)

Betekhtin, V. I.; Kolobov, Yu. R.; Golosova, O. A.; Kardashev, B. K.; Kadomtsev, A. G.; Narykova, M. V.; Ivanov, M. B.; Vershinina, T. N.

2013-10-01

The elastoplastic properties (elastic modulus, amplitude-independent damping ratio, microplastic flow stress) of a Ti-26Nb-7Mo-12Zr titanium β alloy are determined using an acoustic resonance method. The effect of the strain during thermomechanical treatment on the structural features of the micro-crystalline alloy and, hence, its elastoplastic properties is analyzed.

Non-invasive In vivo measurement of the shear modulus of human vocal fold tissue

PubMed Central

Kazemirad, Siavash; Bakhshaee, Hani; Mongeau, Luc; Kost, Karen

2014-01-01

Voice is the essential part of singing and speech communication. Voice disorders significantly affect the quality of life. The viscoelastic mechanical properties of the vocal fold mucosa determine the characteristics of the vocal folds oscillations, and thereby voice quality. In the present study, a non-invasive method was developed to determine the shear modulus of human vocal fold tissue in vivo via measurements of the mucosal wave propagation speed during phonation. Images of four human subjects’ vocal folds were captured using high speed digital imaging (HSDI) and magnetic resonance imaging (MRI) for different phonation pitches, specifically fundamental frequencies between 110 to 440 Hz. The MRI images were used to obtain the morphometric dimensions of each subject's vocal folds in order to determine the pixel size in the high-speed images. The mucosal wave propagation speed was determined for each subject and at each pitch value using an automated image processing algorithm. The transverse shear modulus of the vocal fold mucosa was then calculated from a surface (Rayleigh) wave propagation dispersion equation using the measured wave speeds. It was found that the mucosal wave propagation speed and therefore the shear modulus of the vocal fold tissue were generally greater at higher pitches. The results were in good agreement with those from other studies obtained via in vitro measurements, thereby supporting the validity of the proposed measurement method. This method offers the potential for in vivo clinical assessments of vocal folds viscoelasticity from HSDI. PMID:24433668

The balance between stress resilience and vulnerability is regulated by corticotropin-releasing hormone during the critical postnatal period for sensory development.

PubMed

Cramer, Tomer; Kisliouk, Tatiana; Yeshurun, Shlomo; Meiri, Noam

2015-08-01

Determining whether a stressful event will lead to stress-resilience or vulnerability depends probably on an adjustable stress response set point, which is most likely effective during postnatal sensory development and involves the regulation of corticotrophin-releasing hormone (CRH) expression. During the critical period of thermal-control establishment in 3-day-old chicks, heat stress was found to render resilient or sensitized response, depending on the ambient temperature. These two different responses were correlated with the amount of activation of the hypothalamic-pituitary-adrenal (HPA) axis. The expression of CRH mRNA in the hypothalamic paraventricular nucleus was augmented during heat challenge a week after heat conditioning in chicks which were trained to be vulnerable to heat, while it declined in chicks that were trained to be resilient. To study the role of CRH in HPA-axis plasticity, CRH or Crh-antisense were intracranially injected into the third ventricle. CRH caused an elevation of both body temperature and plasma corticosterone level, while Crh-antisense caused an opposite response. Moreover, these effects had long term implications by reversing a week later, heat resilience into vulnerability and vice versa. Chicks that had been injected with CRH followed by exposure to mild heat stress, normally inducing resilience, demonstrated, a week later, an elevation in body temperature, and Crh mRNA level similar to heat vulnerability, while Crh-antisense injected chicks, which were exposed to harsh temperature, responded in heat resilience. These results demonstrate a potential role for CRH in determining the stress resilience/vulnerability balance. © 2014 Wiley Periodicals, Inc.

Dynamic transverse shear modulus for a heterogeneous fluid-filled porous solid containing cylindrical inclusions

NASA Astrophysics Data System (ADS)

Song, Yongjia; Hu, Hengshan; Rudnicki, John W.; Duan, Yunda

2016-09-01

An exact analytical solution is presented for the effective dynamic transverse shear modulus in a heterogeneous fluid-filled porous solid containing cylindrical inclusions. The complex and frequency-dependent properties of the dynamic shear modulus are caused by the physical mechanism of mesoscopic-scale wave-induced fluid flow whose scale is smaller than wavelength but larger than the size of pores. Our model consists of three phases: a long cylindrical inclusion, a cylindrical shell of poroelastic matrix material with different mechanical and/or hydraulic properties than the inclusion and an outer region of effective homogeneous medium of laterally infinite extent. The behavior of both the inclusion and the matrix is described by Biot's consolidation equations, whereas the surrounding effective medium which is used to describe the effective transverse shear properties of the inner poroelastic composite is assumed to be a viscoelastic solid whose complex transverse shear modulus needs to be determined. The determined effective transverse shear modulus is used to quantify the S-wave attenuation and velocity dispersion in heterogeneous fluid-filled poroelastic rocks. The calculation shows the relaxation frequency and relative position of various fluid saturation dispersion curves predicted by this study exhibit very good agreement with those of a previous 2-D finite-element simulation. For the double-porosity model (inclusions having a different solid frame than the matrix but the same pore fluid as the matrix) the effective shear modulus also exhibits a size-dependent characteristic that the relaxation frequency moves to lower frequencies by two orders of magnitude if the radius of the cylindrical poroelastic composite increases by one order of magnitude. For the patchy-saturation model (inclusions having the same solid frame as the matrix but with a different pore fluid from the matrix), the heterogeneity in pore fluid cannot cause any attenuation in the transverse shear modulus at all. A comparison with the case of spherical inclusions illustrates that the transverse shear modulus for the cylindrical inclusion exhibits more S-wave attenuation than spherical inclusions.

Determining the Gaussian Modulus and Edge Properties of 2D Materials: From Graphene to Lipid Bilayers

NASA Astrophysics Data System (ADS)

Zelisko, Matthew; Ahmadpoor, Fatemeh; Gao, Huajian; Sharma, Pradeep

2017-08-01

The dominant deformation behavior of two-dimensional materials (bending) is primarily governed by just two parameters: bending rigidity and the Gaussian modulus. These properties also set the energy scale for various important physical and biological processes such as pore formation, cell fission and generally, any event accompanied by a topological change. Unlike the bending rigidity, the Gaussian modulus is, however, notoriously difficult to evaluate via either experiments or atomistic simulations. In this Letter, recognizing that the Gaussian modulus and edge tension play a nontrivial role in the fluctuations of a 2D material edge, we derive closed-form expressions for edge fluctuations. Combined with atomistic simulations, we use the developed approach to extract the Gaussian modulus and edge tension at finite temperatures for both graphene and various types of lipid bilayers. Our results possibly provide the first reliable estimate of this elusive property at finite temperatures and appear to suggest that earlier estimates must be revised. In particular, we show that, if previously estimated properties are employed, the graphene-free edge will exhibit unstable behavior at room temperature. Remarkably, in the case of graphene, we show that the Gaussian modulus and edge tension even change sign at finite temperatures.

Functional similarities in the mechanical design of the aorta in lower vertebrates and mammals.

PubMed

Gibbons, C A; Shadwick, R E

1989-12-01

The mechanical properties of the aorta from the toad Bufo marinus, the lizard Gekko gecko and the garter snake Thamnophis radix were compared to those of the rat, by inflation of vessel segments in vitro. The arteries of the lower vertebrates, like those of mammals, were compliant, highly resilient, and non-linearly elastic. The elastic modulus of the artery wall was similar in the lower vertebrates and mammals, at their respective mean physiological pressures. We conclude that the aorta in each of these animals is suitably designed to function effectively as an elastic pulse smoothing component in the circulation; differences in the pressure wave transmission characteristics of lower vertebrates and mammals do not result from dissimilarities in arterial elastic properties, but from substantial differences in heart rate of these two groups.

Magnetic-field-dependent shear modulus of a magnetorheological elastomer based on natural rubber

NASA Astrophysics Data System (ADS)

Yang, In-Hyung; Yoon, Ji-Hyun; Jeong, Jae-Eun; Jeong, Un-Chang; Kim, Jin-Su; Chung, Kyung Ho; Oh, Jae-Eung

2013-01-01

A magnetorheological elastomer (MRE) is a smart material that has a reversible and variable modulus in a magnetic field. Natural rubber, which has better physical properties than silicone matrices, was used as a matrix in the fabrication of the MREs used in this study. Carbonyl iron powder (CIP), which has a rapid magnetic reaction, was selected as a magnetic material to generate the magnetic-field-dependent modulus in the MREs. The MRE specimens were cured in an anisotropic mold, which could be used to induce a uniaxial magnetic field via permanent magnets, to control the orientation of the CIP, and the shear modulus of the MREs was evaluated under a magnetic field induced by using a magnetic flux generator (MFG). Because the use of a conventional evaluation system to determine the magnetic-field-dependent shear modulus of the MREs was difficult, an evaluation system based on single degree-of-freedom vibration and electromagnetics that included an MFG, which is a device that generates a magnetic field via a variable induced current, was designed. An electromagnetic finite element method (FEM) analysis and design of experiments (DoE) techniques were employed to optimize the magnetic flux density generated by the MFG. The optimized system was verified over the range to determine the magnetic flux density generated by the MFG in order to use a magnetic circuit analysis to identify the existence of magnetic saturation. A variation in the shear modulus was observed with increasing CIP volume fraction and induced current. The experimental results revealed that the maximum variation in the shear modulus was 76.3% for 40 vol% CIP at an induced current of 4 A. With these results, the appropriate CIP volume fraction, induced current, and design procedure of the MFG can be proposed as guidelines for applications of MREs based on natural rubber.

Validity and Reliability of the Academic Resilience Scale in Turkish High School

ERIC Educational Resources Information Center

Kapikiran, Sahin

2012-01-01

The present study aims to determine the validity and reliability of the academic resilience scale in Turkish high school. The participances of the study includes 378 high school students in total (192 female and 186 male). A set of analyses were conducted in order to determine the validity and reliability of the study. Firstly, both exploratory…

Effect of long-term successive storm flows on water reclamation plant resilience.

PubMed

Zhu, Jun-Jie; Anderson, Paul R

2017-03-15

A water reclamation plant (WRP) needs to be resilient to successfully operate through different kinds of perturbations. Perturbations such as storm events, especially long-term successive storm flows, can adversely affect operations. A better understanding of these effects can provide benefits for plant operation, in terms of effluent quality and energy efficiency. However, the concept of resilience for a WRP has not been widely studied, and we are not aware of any studies specifically related to storm flows. In this work we applied measures of resistance and recovery time to quantify resilience, and used a WRP simulation model to investigate how different storm flow characteristics (flowrate and duration) and the amount of aeration influence resilience. Not surprisingly, increasing storm flowrate leads to decreasing resilience. Although the aeration rate plays an important role in determining resilience, there is an aeration threshold (6 m 3 /s for our WRP model); higher aeration rates do not increase resilience. Results suggest that aeration costs could be reduced by as much as 50% while still maintaining the resilience needed to meet effluent quality permit requirements through the perturbations examined in this study. Copyright © 2016 Elsevier Ltd. All rights reserved.

Resilience to urban poverty: theoretical and empirical considerations for population health.

PubMed

Sanders, Anne E; Lim, Sungwoo; Sohn, Woosung

2008-06-01

To better understand the trajectory that propels people from poverty to poor health, we investigated health resilience longitudinally among African American families with incomes below 250% of the federal poverty level. Health resilience is the capacity to maintain good health in the face of significant adversity. With higher levels of tooth retention as a marker of health resilience, we used a social-epidemiological framework to define capacity for health resilience through a chain of determinants starting in the built environment (housing quality) and community context (social support) to familial influences (religiosity) and individual mental health and health behavior. Odds of retaining 20 or more teeth were 3 times as likely among adults with resilience versus more-vulnerable adults (odds ratio=3.1; 95% confidence interval [CI]=1.3, 7.4). Children of caregivers with resilience had a lower incident rate of noncavitated tooth decay at 18- to 24-month follow-up (incidence risk ratio=0.8; 95% CI=0.7, 0.9) compared with other children. Health resilience to poverty was supported by protective factors in the built and social environments. When poverty itself cannot be eliminated, improving the quality of the built and social environments will foster resilience to its harmful health effects.

A new multidimensional measure of personal resilience and its use: Chinese nurse resilience, organizational socialization and career success.

PubMed

Wei, Wei; Taormina, Robert J

2014-12-01

This study refined the concept of resilience and developed four valid and reliable subscales to measure resilience, namely, Determination, Endurance, Adaptability and Recuperability. The study also assessed their hypothesized relationships with six antecedent variables (worry, physiological needs satisfaction, organizational socialization, conscientiousness, future orientation and Chinese values) and with one outcome variable (nurses' career success). The four new 10-item subscale measures of personal resilience were constructed based on their operational definitions and tested for their validity and reliability. All items were included in a questionnaire completed by 244 full-time nurses at two hospitals in China. All four measures demonstrated concurrent validity and had high reliabilities (from 0.74 to 0.78). The hypothesized correlations with the personality and organizational variables were statistically significant and in the predicted directions. Regression analyses confirmed these relationships, which explained 25-32% of the variance for the four resilience facets and 27% of the variance for the nurses' career success. The results provided strong evidence that organizational socialization facilitates resilience, that resilience engenders career success and that identifying the four resilience facets permits a more complete understanding of personal resilience, which could benefit nurses, help nurse administrators with their work and also help in treating patients. © 2014 John Wiley & Sons Ltd.

Effect of single-particle magnetostriction on the shear modulus of compliant magnetoactive elastomers.

PubMed

Kalita, Viktor M; Snarskii, Andrei A; Shamonin, Mikhail; Zorinets, Denis

2017-03-01

The influence of an external magnetic field on the static shear strain and the effective shear modulus of a magnetoactive elastomer (MAE) is studied theoretically in the framework of a recently introduced approach to the single-particle magnetostriction mechanism [V. M. Kalita et al., Phys. Rev. E 93, 062503 (2016)10.1103/PhysRevE.93.062503]. The planar problem of magnetostriction in an MAE with magnetically soft inclusions in the form of a thin disk (platelet) having the magnetic anisotropy in the plane of this disk is solved analytically. An external magnetic field acts with torques on magnetic filler particles, creates mechanical stresses in the vicinity of inclusions, induces shear strain, and increases the effective shear modulus of these composite materials. It is shown that the largest effect of the magnetic field on the effective shear modulus should be expected in MAEs with soft elastomer matrices, where the shear modulus of the matrix is less than the magnetic anisotropy constant of inclusions. It is derived that the effective shear modulus is nonlinearly dependent on the external magnetic field and approaches the saturation value in magnetic fields exceeding the field of particle anisotropy. It is shown that model calculations of the effective shear modulus correspond to a phenomenological definition of effective elastic moduli and magnetoelastic coupling constants. The obtained theoretical results compare well with known experimental data. Determination of effective elastic coefficients in MAEs and their dependence on magnetic field is discussed. The concentration dependence of the effective shear modulus at higher filler concentrations has been estimated using the method of Padé approximants, which predicts that both the absolute and relative changes of the magnetic-field-dependent effective shear modulus will significantly increase with the growing concentration of filler particles.

Effect of single-particle magnetostriction on the shear modulus of compliant magnetoactive elastomers

NASA Astrophysics Data System (ADS)

Kalita, Viktor M.; Snarskii, Andrei A.; Shamonin, Mikhail; Zorinets, Denis

2017-03-01

The influence of an external magnetic field on the static shear strain and the effective shear modulus of a magnetoactive elastomer (MAE) is studied theoretically in the framework of a recently introduced approach to the single-particle magnetostriction mechanism [V. M. Kalita et al., Phys. Rev. E 93, 062503 (2016), 10.1103/PhysRevE.93.062503]. The planar problem of magnetostriction in an MAE with magnetically soft inclusions in the form of a thin disk (platelet) having the magnetic anisotropy in the plane of this disk is solved analytically. An external magnetic field acts with torques on magnetic filler particles, creates mechanical stresses in the vicinity of inclusions, induces shear strain, and increases the effective shear modulus of these composite materials. It is shown that the largest effect of the magnetic field on the effective shear modulus should be expected in MAEs with soft elastomer matrices, where the shear modulus of the matrix is less than the magnetic anisotropy constant of inclusions. It is derived that the effective shear modulus is nonlinearly dependent on the external magnetic field and approaches the saturation value in magnetic fields exceeding the field of particle anisotropy. It is shown that model calculations of the effective shear modulus correspond to a phenomenological definition of effective elastic moduli and magnetoelastic coupling constants. The obtained theoretical results compare well with known experimental data. Determination of effective elastic coefficients in MAEs and their dependence on magnetic field is discussed. The concentration dependence of the effective shear modulus at higher filler concentrations has been estimated using the method of Padé approximants, which predicts that both the absolute and relative changes of the magnetic-field-dependent effective shear modulus will significantly increase with the growing concentration of filler particles.

What Do We Mean by 'Community Resilience'? A Systematic Literature Review of How It Is Defined in the Literature.

PubMed

Patel, Sonny S; Rogers, M Brooke; Amlôt, Richard; Rubin, G James

2017-02-01

Government, industry and charitable organisations have an increasing focus on programs intended to support community resilience to disasters. But has consensus been reached as to what defines 'community resilience' and what its core characteristics are? We undertook a systematic literature review of definitions of community resilience related to disasters. We conducted an inductive thematic analysis of the definitions and descriptions that we identified, in order to determine the proposed characteristics of community resilience prior to, during and after a disaster. We identified 80 relevant papers. There was no evidence of a common, agreed definition of community resilience. In spite of this, evidence was found of nine core elements of community resilience that were common among the definitions. The core elements were: local knowledge, community networks and relationships, communication, health, governance and leadership, resources, economic investment, preparedness, and mental outlook. Within these core elements, we identified 19 sub-elements linked to community resilience. Our findings show that community resilience remains an amorphous concept that is understood and applied differently by different research groups. Yet in spite of the differences in conception and application, there are well-understood elements that are widely proposed as important for a resilient community. A focus on these individual elements may be more productive than attempting to define and study community resilience as a distinct concept.

What Do We Mean by 'Community Resilience'? A Systematic Literature Review of How It Is Defined in the Literature

PubMed Central

Patel, Sonny S.; Rogers, M. Brooke; Amlôt, Richard; Rubin, G. James

2017-01-01

Background: Government, industry and charitable organisations have an increasing focus on programs intended to support community resilience to disasters. But has consensus been reached as to what defines 'community resilience' and what its core characteristics are? Methods: We undertook a systematic literature review of definitions of community resilience related to disasters. We conducted an inductive thematic analysis of the definitions and descriptions that we identified, in order to determine the proposed characteristics of community resilience prior to, during and after a disaster. Results: We identified 80 relevant papers. There was no evidence of a common, agreed definition of community resilience. In spite of this, evidence was found of nine core elements of community resilience that were common among the definitions. The core elements were: local knowledge, community networks and relationships, communication, health, governance and leadership, resources, economic investment, preparedness, and mental outlook. Within these core elements, we identified 19 sub-elements linked to community resilience. Conclusion: Our findings show that community resilience remains an amorphous concept that is understood and applied differently by different research groups. Yet in spite of the differences in conception and application, there are well-understood elements that are widely proposed as important for a resilient community. A focus on these individual elements may be more productive than attempting to define and study community resilience as a distinct concept. PMID:29188132

Parenting style, resilience, and mental health of community-dwelling elderly adults in China.

PubMed

Zhong, Xue; Wu, Daxing; Nie, Xueqing; Xia, Jie; Li, Mulei; Lei, Feng; Lim, Haikel A; Kua, Ee-Heok; Mahendran, Rathi

2016-07-08

Given the increasing elderly population worldwide, the identification of potential determinants of successful ageing is important. Many studies have shown that parenting style and mental resilience may influence mental health; however, little is known about the psychological mechanisms that underpin this relationship. The current study sought to explore the relationships among mental resilience, perceptions of parents' parenting style, and depression and anxiety among community-dwelling elderly adults in China. In total, 439 community-dwelling elderly Chinese adults aged 60-91 years completed the Personal and Parents' Parenting Style Scale, Connor-Davidson Resilience Scale, Zung Self-Rating Depression Scale, and Zung Self-Rating Anxiety Scale. Elderly adults whose parents preferred positive and authoritative parenting styles had higher levels of mental resilience and lower levels of depression and anxiety. Elderly adults parented in the authoritarian style were found to have higher levels of depression and anxiety, with lower mental resilience. The findings of this study provide evidence related to successful ageing and coping with life pressures, and highlight the important effects of parenting on mental health. The results suggest that examination of the proximal determinants of successful ageing is not sufficient-distal factors may also contribute to the 'success' of ageing by modifying key psychological dispositions that promote adaptation to adversity.

In vivo quantification of the shear modulus of the human Achilles tendon during passive loading using shear wave dispersion analysis.

PubMed

Helfenstein-Didier, C; Andrade, R J; Brum, J; Hug, F; Tanter, M; Nordez, A; Gennisson, J-L

2016-03-21

The shear wave velocity dispersion was analyzed in the Achilles tendon (AT) during passive dorsiflexion using a phase velocity method in order to obtain the tendon shear modulus (C 55). Based on this analysis, the aims of the present study were (i) to assess the reproducibility of the shear modulus for different ankle angles, (ii) to assess the effect of the probe locations, and (iii) to compare results with elasticity values obtained with the supersonic shear imaging (SSI) technique. The AT shear modulus (C 55) consistently increased with the ankle dorsiflexion (N = 10, p < 0.05). Furthermore, the technique showed a very good reproducibility (all standard error of the mean values <10.7 kPa and all coefficient of variation (CV) values ⩽ 0.05%). In addition, independently from the ankle dorsiflexion, the shear modulus was significantly higher in the proximal location compared to the more distal one. The shear modulus provided by SSI was always lower than C55 and the difference increased with the ankle dorsiflexion. However, shear modulus values provided by both methods were highly correlated (R = 0.84), indicating that the conventional shear wave elastography technique (SSI technique) can be used to compare tendon mechanical properties across populations. Future studies should determine the clinical relevance of the shear wave dispersion analysis, for instance in the case of tendinopathy or tendon tear.

A novel approach to determine the thermal transition of gum powder/hydro-gels using dynamic mechanical analysis

NASA Astrophysics Data System (ADS)

Nagamadhu, M.; Jeyaraj, P.; Kumar, G. C. Mohan

2018-04-01

The dynamic characterization of materials plays a major role in the present area. The many researchers are worked on solid materials and its characterization, it can be tested using dynamic mechanical analyzer (DMA), however, no such work on powder a semiliquid samples. The powder and liquid samples can also easily characterization as like solid samples using DMA. These powder samples are analyzed with a material pocket method which can be used to accurately determine very low levels of variation in powder properties, due to the high sensitivity of DMA to glass transitions. No such DMA studies on hydrogel and Gum powders. The gum powders are used in various applications start from food industries, pharmacy, natural gums paste, biomedical applications etc. among all this applications gum Ghatti is one of the powders using for varies applications. Around 50 milligrams of Ghatti powders are placed inside material pocket and analyzed storage modulus (G'), loss modulus (G″) and tan delta (δ). Also, understand the curing and glass transition effect using water, glycerin and superplastic from room temperature to 200°C. The result shows that storage modulus decreases with increase in temperature in pure Ghatti powder. The surprising improvement in storage modulus was found with an increase in temperature with addition of water, glycerin, and superplastic. However, loss modulus and tan delta are also having very significant influence and also shows a clear peak of the tan delta. The loss modulus results were found to be improved by adding solidifying agents, along with this water and superplastic better influence. But glycerine found to be hydrogel in nature and thermodynamic properties are much influenced by frequency.

The structure of disaster resilience: a framework for simulations and policy recommendations

NASA Astrophysics Data System (ADS)

Edwards, J. H. Y.

2015-04-01

In this era of rapid climate change there is an urgent need for interdisciplinary collaboration and understanding in the study of what determines resistance to disasters and recovery speed. This paper is an economist's contribution to that effort. It traces the entrance of the word "resilience" from ecology into the social science literature on disasters, provides a formal economic definition of resilience that can be used in mathematical modeling, incorporates this definition into a multilevel model that suggests appropriate policy roles and targets at each level, and draws on the recent empirical literature on the economics of disaster, searching for policy handles that can stimulate higher resilience. On the whole it provides a framework for simulations and for formulating disaster resilience policies.

The structure of disaster resilience: a framework for simulations and policy recommendations

NASA Astrophysics Data System (ADS)

Edwards, J. H. Y.

2014-09-01

In this era of rapid climate change there is an urgent need for interdisciplinary collaboration and understanding in the study of what determines resistance to disasters and recovery speed. This paper is an economist's contribution to that effort. It traces the entrance of the word "resilience" from ecology into the social science literature on disasters, provides a formal economic definition of resilience that can be used in mathematical modeling, incorporates this definition into a multilevel model that suggests appropriate policy roles and targets at each level, and draws on the recent empirical literature on the economics of disaster searching for policy handles that can stimulate higher resilience. On the whole it provides a framework for simulations and for formulating disaster resilience policies.

Shear modulus of porcine coronary artery in reference to a new strain measure.

PubMed

Zhang, Wei; Lu, Xiao; Kassab, Ghassan S

2007-11-01

To simplify the stress-strain relationship of blood vessels, we define a logarithmic-exponential (log-exp) strain measure to absorb the nonlinearity. As a result, the constitutive relation between the second Piola-Kirchhoff stress and the log-exp strain can be written as a generalized Hooke's law. In this work, the shear modulus of porcine coronary arteries is determined from the experimental data in inflation-stretch-torsion tests. It is found that the shear modulus with respect to the log-exp strain can be viewed as a material constant in the full range of elasticity, and the incremental shear modulus for Cauchy shear stress and small shear strain at various loading levels can be predicted by the proposed Hooke's law. This result further validates the linear constitutive relation for blood vessels when shear deformation is involved.

Measurement of leaky Lamb wave dispersion curves with application on coating characterization

NASA Astrophysics Data System (ADS)

Lee, Yung-Chun; Cheng, Sheng Wen

2001-04-01

This paper describes a new measurement system for measuring dispersion curves of leaky Lamb waves. The measurement system is based on a focusing PVDF transducer, the defocusing measurement, the V(f,z) waveform processing method, and an image displaying technique. The measurement system is applied for the determination of thin-film elastic properties, namely Young's modulus and shear modulus, by the inversion of dispersion curves measured from a thin-film/plate configuration. Elastic constants of electro-deposited nickel layers are determined with this method.

Clinical correlates of resilience factors in geriatric depression.

PubMed

Laird, Kelsey T; Lavretsky, Helen; Paholpak, Pattharee; Vlasova, Roza M; Roman, Michael; St Cyr, Natalie; Siddarth, Prabha

2018-01-16

Traditional perspectives conceptualize resilience as a trait and depression as resulting from resilience deficiency. However, research indicates that resilience varies substantially even among adults who are clinically depressed, as well as across the lifespan of an individual. Few studies have investigated resilience in depression, and even fewer have examined resilience in depressed older adults. Three hundred thirty-seven adults ≥60 years with major depressive disorder completed the Connor-Davidson Resilience Scale (CD-RISC) and measures of mental health, quality of life (QOL), and medical comorbidity. Exploratory factor analysis was used to explore the factor structure of the CD-RISC. Correlations and general linear models were used to examine associations between resilience and other variables. The rotated component matrix indicated a four-factor model. Sorting of items by highest factor loading revealed constructs associated with (1) grit, (2) active coping self-efficacy, (3) accommodative coping self-efficacy, and (4) spirituality. Resilience was significantly correlated with increased age, lower cognitive functioning, greater cerebrovascular risk, and greater medical comorbidity. Resilience was negatively associated with mental health symptoms (depression, apathy, and anxiety) and positively associated with QOL. The final optimal model identified less depression, less apathy, greater medical comorbidity, higher QOL, and minority (non-White) race as factors that significantly explained variability in resilience. Resilience was significantly associated with a range of mental health constructs in a sample of older adults with depression. Future clinical trials and dismantling studies may help determine whether interventions targeting grit, active coping, accommodative coping, and spirituality can increase resilience and help prevent and treat depression in older adults.

Bending strength of water-soaked glued laminated beams

Treesearch

Ronald W. Wolfe; Russell C. Moody

1978-01-01

The effects of water soaking on the bending strength and stiffness of laminated timber were determined by deriving wet-dry ratios for these properties. Values for these ratios, when compared to currently recommended wet use factors, confirm the value now used for modulus of rupture. For modulus of elasticity, the reduction due to water soaking was found to be less than...

Characterization of Heat Treated Titanium-Based Implants by Nondestructive Eddy Current and Ultrasonic Tests

NASA Astrophysics Data System (ADS)

Mutlu, Ilven; Ekinci, Sinasi; Oktay, Enver

2014-06-01

This study presents nondestructive characterization of microstructure and mechanical properties of heat treated Ti, Ti-Cu, and Ti-6Al-4V titanium-based alloys and 17-4 PH stainless steel alloy for biomedical implant applications. Ti, Ti-Cu, and 17-4 PH stainless steel based implants were produced by powder metallurgy. Ti-6Al-4V alloy was investigated as bulk wrought specimens. Effects of sintering temperature, aging, and grain size on mechanical properties were investigated by nondestructive and destructive tests comparatively. Ultrasonic velocity in specimens was measured by using pulse-echo and transmission methods. Electrical conductivity of specimens was determined by eddy current tests. Determination of Young's modulus and strength is important in biomedical implants. Young's modulus of specimens was calculated by using ultrasonic velocities. Calculated Young's modulus values were compared and correlated with experimental values.

Determination of mechanical properties of polymer film materials

NASA Technical Reports Server (NTRS)

Hughes, E. J.; Rutherford, J. L.

1975-01-01

Five polymeric film materials, Tedlar, Teflon, Kapton H, Kapton F, and a fiberglass reinforced polyimide, PG-402, in thickness ranging from 0.002 to 0.005 inch, were tested over a temperature range of -195 to 200 C in the "machine" and transverse direction to determine: elastic modulus, Poisson's ratio, three percent offset yield stress, fracture stress, and strain to fracture. The elastic modulus, yield stress and fracture stress decreased with increasing temperature for all the materials while the fracture strain increased. Teflon and Tedlar had the greatest temperature dependence and PG-402 the least. At 200 C the Poisson ratio values ranged from 0.39 to 0.5; they diminished as the temperature decreased covering a range of 0.26 to 0.42 at -195 C. Shortening the gauge length from eight inches to one inch increased the strain to fracture and lowered the elastic modulus values.

Enhancing resilience in registered aged care nurses.

PubMed

Cameron, Fiona; Brownie, Sonya

2010-06-01

To identify the factors that impact the resilience of registered aged care nurses, that is their capacity to adapt to the physical, mental and emotional demands of working in aged care facilities. This study explored the lived experience of nine registered nurses working in residential aged care facilities on the Sunshine Coast, Queensland, who were asked to reflect on the phenomenon of resilience in the workplace. This study found that clinical expertise, a sense of purpose in a holistic care environment, a positive attitude and work-life balance are important determinants of resilience in aged care nurses. Resilience in nurses in residential aged care facilities is enhanced when they are able to maintain long-term, meaningful relationships with residents. Collegial support that provides opportunities to debrief and validate experiences as well as the use of humour to defuse stress promotes well-being and builds resilience in the workplace.

Racial Segregation, Economic Growth, and Resilience to Natural Disasters

NASA Astrophysics Data System (ADS)

Fernandez, S.; Li, H.; Ganguly, A.

2008-05-01

Resilience to natural disasters is often defined as the ability of a community to recover from disaster disruption. Thus, resilience depends on various socioeconomic factors which influence the short- and long-term impacts of natural disasters as well as the resources that a community can bring to bear on the recovery process. One objective of this research is to tease out the determinants of resilience from a variety of possible indicators and data sources. A second objective is to test hypotheses which in turn are based on prior reports in the literature: Racial segregation has a negative impact, while economic growth has a positive impact, on resilience. We choose the Biloxi-Gulfport-Pascagoula, MS Metropolitan Area, and New Orleans Metropolitan Area, for our case studies. The study areas included nine counties and parishes that are located in the Hurricane Katrina impact area. The nine counties and parishes were Hancock County, Harrison County, and Jackson County in Mississippi, and Jefferson Parish, Orleans Parish, Plaquemines Parish, St. Bernard Parish, St. Charles Parish, and St. Tammany Parish in Louisiana. The three counties make up the Biloxi-Gulfport-Pascagoula, MS Metropolitan Area, and the six parishes are components of New Orleans Metropolitan Area. The determinants of resilience for this study were based on two considerations. First, we followed the political, military or security, economic, social, informational and infrastructural (PMESII) framework, which succinctly describes the resources available to a community. Second, we were pragmatically constrained by data availability. Five variables were selected as plausible determinants of resilience: (i) return of the original population, (ii) employment recovery, (iii) tax collected, (iv) building permit restoration, and (v) school re-opening information. The five variables were found to be highly correlated. We created three resilience indices, one by simple addition, another by addition of the normalized Z scores, and a third by principal component analysis. The indices were computed by bringing together the relevant PMESII dimensions. The three indices were found to be highly, and negatively, correlated with the social vulnerability index created by Cutter (2001). This is not surprising, since the Cutter indices themselves are created by dimensionality reduction techniques applied on plausible determinants of resilience. Our indices were negatively correlated with racial segregation, which confirmed one hypothesis. They also negatively correlated with economic growth rate. By examining the industrial structures of each county (or parish), we found a negative correlation between economic growth and natural disaster resilience indices reflects the economic constraints of the local governments rather than the recovery capability of the communities. Our findings provide new insights for resilience research. First, we find resilience indices may be developed by combining the relevant PMESII dimensions, even though the predictive power of such indices needs to be tested further. Second, to build a resilient community, a mixed housing policy and a place-based anti-poverty policy are suggested. The results are preliminary and the research needs to be strengthened in three areas. First, we have only examined the social and economic dimensions because of data availability. Data along other dimensions of the PMESII framework need to be collected ad utilized. Second, we collected data only for six county-level communities. Additional case studies can test the robustness of the insights.

Assessing the resilience of Norway spruce forests through a model-based reanalysis of thinning trials☆

PubMed Central

Seidl, Rupert; Vigl, Friedrich; Rössler, Günter; Neumann, Markus; Rammer, Werner

2017-01-01

As a result of a rapidly changing climate the resilience of forests is an increasingly important property for ecosystem management. Recent efforts have improved the theoretical understanding of resilience, yet its operational quantification remains challenging. Furthermore, there is growing awareness that resilience is not only a means to addressing the consequences of climate change but is also affected by it, necessitating a better understanding of the climate sensitivity of resilience. Quantifying current and future resilience is thus an important step towards mainstreaming resilience thinking into ecosystem management. Here, we present a novel approach for quantifying forest resilience from thinning trials, and assess the climate sensitivity of resilience using process-based ecosystem modeling. We reinterpret the wide range of removal intensities and frequencies in thinning trials as an experimental gradient of perturbation, and estimate resilience as the recovery rate after perturbation. Our specific objectives were (i) to determine how resilience varies with stand and site conditions, (ii) to assess the climate sensitivity of resilience across a range of potential future climate scenarios, and (iii) to evaluate the robustness of resilience estimates to different focal indicators and assessment methodologies. We analyzed three long-term thinning trials in Norway spruce (Picea abies (L.) Karst.) forests across an elevation gradient in Austria, evaluating and applying the individual-based process model iLand. The resilience of Norway spruce was highest at the montane site, and decreased at lower elevations. Resilience also decreased with increasing stand age and basal area. The effects of climate change were strongly context-dependent: At the montane site, where precipitation levels were ample even under climate change, warming increased resilience in all scenarios. At lower elevations, however, rising temperatures decreased resilience, particularly at precipitation levels below 750–800 mm. Our results were largely robust to different focal variables and resilience definitions. Based on our findings management can improve the capacity to recover from partial disturbances by avoiding overmature and overstocked conditions. At increasingly water limited sites a strongly decreasing resilience of Norway spruce will require a shift towards tree species better adapted to the expected future conditions. PMID:28860674

Measuring the elastic properties of fine wire.

PubMed

Fallen, C T; Costello, J; Crawford, G; Schmidt, J A

2001-01-01

The elastic moduli of fine wires made from MP35N and 304SS used in implantable biomedical devices are assumed to be the same as those published in the literature. However, the cold working required to manufacture the wire significantly alters the elastic moduli of the material. We describe three experiments performed on fine wire made from MP35N and 304SS. The experimentally determined Young's and shear modulus of both wire types were significantly less than the moduli reported in the literature. Young's modulus differed by as much as 26%, and the shear modulus differed by as much as 14% from reported values.

Constitutive Modeling of the Mechanical Properties of Optical Fibers

NASA Technical Reports Server (NTRS)

Moeti, L.; Moghazy, S.; Veazie, D.; Cuddihy, E.

1998-01-01

Micromechanical modeling of the composite mechanical properties of optical fibers was conducted. Good agreement was obtained between the values of Young's modulus obtained by micromechanics modeling and those determined experimentally for a single mode optical fiber where the wave guide and the jacket are physically coupled. The modeling was also attempted on a polarization-maintaining optical fiber (PANDA) where the wave guide and the jacket are physically decoupled, and found not to applicable since the modeling required perfect bonding at the interface. The modeling utilized constituent physical properties such as the Young's modulus, Poisson's ratio, and shear modulus to establish bounds on the macroscopic behavior of the fiber.

Influence of elastic parameters on the evolution of elasticity modulus of thin films

NASA Astrophysics Data System (ADS)

Gacem, A.; Doghmane, A.; Hadjoub, Z.; Beldi, I.; Doghmane, M.

2012-09-01

In recent years, it appears many structures in the form of thin films or multilayers, used as coatings for surface protection, or to provide materials with new properties different from those of substrates. These properties are the subject of a growing number of studies in order to produce Nano or micro structures with different degrees of quality, and cost as well as the manufacture of thin film properties more functional and more controllable. As the thicknesses are close to micrometric or nanometric scales, the modulus of elasticity are difficult to measure and experimental results are rarely published in the literature. In this context, we propose an analytical qualitative methodology to describe the influence of acoustic parameters of thin films on the evolution of elastic moduli the most used. This method is based on the determination of the acoustic signature V(z) of several thin layers deposited on different substrates, as well the information on the propagation velocity of ultrasonic waves are obtained. Thus, the dispersion curves representing the variation of the modulus of elasticity (Young and the shear), were determined. We have noticed that, according to the type of substrate (light, medium or heavy), we observed the appearance of some anomalies in curves that are generally associated with changes in the acoustic properties of each of the examined layers. We have shown that these anomalies are mainly due to the effect loading, and represent one of the fundamental parameters determining the appearance or disappearance of a phenomenon and represent one of the basic parameters determining the appearance or disappearance of phenomena. Finally, we determine the Poisson ratio of thin films in order to calculate other elastic parameters such as the compressor modulus.

Resilient moduli of typical Missouri soils and unbound granular base materials.

DOT National Transportation Integrated Search

2009-01-01

The objective of this project was to determine the resilient moduli for common Missouri subgrade soils and typical unbound granular base materials in accordance with the AASHTO T 307 test method. The results allow Missouri Department of Transportatio...

Determination of the fundamental properties of an M31 globular cluster from main-sequence photometry

NASA Astrophysics Data System (ADS)

Ma, Jun

2013-02-01

We determined the age of the M31 globular cluster B379 using isochrones of the Padova stellar evolutionary models. At the same time, the cluster's metal abundance, its distance modulus, and reddening value were also obtained. The results obtained in this paper are consistent with previous determinations, including the age. Brown et al. constrained the age of B379 by comparing its color-magnitude diagram with isochrones of the 2006 VandenBerg models. Therefore, this paper confirms the consistency of the age scale of B379 between the Padova isochrones and the 2006 VandenBerg isochrones. The results of B379 obtained in this paper are: metallicity [M/H] = log(Z/Z⊙) = -0.325 dex, age τ = 11.0 +/- 1.5 Gyr, reddening E(B - V) = 0.08 mag, and distance modulus (m - M)0 = 24.44 +/- 0.10 mag. Using the metallicity, the reddening value and the distance modulus obtained in this paper, we constrained the age of B379 by comparing its multicolor photometry with theoretical stellar population synthesis models. The age of B379 obtained is 10.6-0.76 +0.92 Gyr, which is in very good agreement with the determination from main-sequence photometry.

Study on axial strength of a channel-shaped pultruded GFRP member

NASA Astrophysics Data System (ADS)

Matsumoto, Yukihiro; Satake, Chito; Nisida, Kenji

2017-10-01

Fiber reinforced polymers (FRP) are widely used in vehicle and aerospace applications because of their lightweight and high-strength characteristics. Additionally, FRPs are increasingly applied to building structures. However, the elastic modulus of glass fiber reinforced polymers (GFRPs) is lower than that of steel. Hence, the evaluating the buckling strength of GFRP members for design purpose is necessary. The buckling strength is determined by Euler buckling mode as well as local buckling. In this study investigated the compressive strength of GFRP members subjected to axial compression through experiments and theoretical calculations. The adopted GFRP member was a channel-shaped GFRP, which was molded via pultrusion, at various lengths. Although, the mechanical properties as longitudinal elastic modulus and fiber volume fraction and strength of GFRP members subjected, to axial can be easily evaluated, evaluating transverse elastic modulus and shear modulus in typical material tests is difficult in standard section. Therefore the composite law was used in this study. As a result, we confirmed that the axial strength of a GFRP member could be calculated by a theoretical evaluation method utilizing longitudinal elastic modulus and fiber volume fraction.

Crack Driving Forces in a Multilayered Coating System for Ceramic Matrix Composite Substrates

NASA Technical Reports Server (NTRS)

Ghosn, Louis J.; Zhu, Dongming; Miller, Robert A.

2005-01-01

The effects of the top coating thickness, modulus and shrinkage strains on the crack driving forces for a baseline multilayer Yttria-Stabilized-Zirconia/Mullite/Si thermal and environment barrier coating (TEBC) system for SiC/SiC ceramic matrix composite substrates are determined for gas turbine applications. The crack driving forces increase with increasing modulus, and a low modulus thermal barrier coating material (below 10 GPa) will have no cracking issues under the thermal gradient condition analyzed. Since top coating sintering increases the crack driving forces with time, highly sintering resistant coatings are desirable to maintain a low tensile modulus and maintain a low crack driving force with time. Finite element results demonstrated that an advanced TEBC system, such as ZrO2/HfO2, which possesses improved sintering resistance and high temperature stability, exhibited excellent durability. A multi-vertical cracked structure with fine columnar spacing is an ideal strain tolerant coating capable of reducing the crack driving forces to an acceptable level even with a high modulus of 50 GPa.

The moderation of resilience on the negative effect of pain on depression and post-traumatic growth in individuals with spinal cord injury.

PubMed

Min, Jung-Ah; Lee, Chang-Uk; Hwang, Sung-Il; Shin, Jung-In; Lee, Bum-Suk; Han, Sang-Hoon; Ju, Hye-In; Lee, Cha-Yeon; Lee, Chul; Chae, Jeong-Ho

2014-01-01

To determine the moderating effect of resilience on the negative effects of chronic pain on depression and post-traumatic growth. Community-dwelling individuals with SCI (n = 37) were recruited at short-term admission for yearly regular health examination. Participants completed self-rating standardized questionnaires measuring pain, resilience, depression and post-traumatic growth. Hierarchical linear regression analysis was performed to identify the moderating effect of resilience on the relationships of pain with depression and post-traumatic growth after controlling for relevant covariates. In the regression model of depression, the effect of pain severity on depression was decreased (β was changed from 0.47 to 0.33) after entering resilience into the model. In the final model, both pain and resilience were significant independent predictors for depression (β = 0.33, p = 0.038 and β = -0.47, p = 0.012, respectively). In the regression model of post-traumatic growth, the effect of pain severity became insignificant after entering resilience into the model. In the final model, resilience was a significant predictor (β = 0.51, p = 0.016). Resilience potentially mitigated the negative effects of pain. Moreover, it independently contributed to reduced depression and greater post-traumatic growth. Our findings suggest that resilience might provide a potential target for intervention in SCI individuals.

Strategies for enhancing medical student resilience: student and faculty member perspectives.

PubMed

Farquhar, Julia; Kamei, Robert; Vidyarthi, Arpana

2018-01-12

To improve programs aimed to enhance medical student resiliency, we examined both medical student and faculty advisor perspectives on resiliency-building in an Asian medical school. In two separate focus groups, a convenience sample of 8 MD-PhD students and 8 faculty advisors were asked to identify strategies for enhancing resilience. Using thematic analysis, two researchers independently examined discussion transcripts and field notes and determined themes through a consensus process. They then compared the themes to discern similarities and differences between these groups. Themes from the student suggestions for increasing resilience included "Perspective changes with time and experience", "Defining effective advisors," and "Individual paths to resiliency". Faculty-identified themes were "Structured activities to change student perspectives," "Structured teaching of coping strategies", and "Institution-wide social support". Students described themselves as individuals building their own resilience path and preferred advisors who were not also evaluators. Faculty, however, suggested systematic, structural ways to increase resilience. Students and advisors identified some common, and many distinct strategies for enhancing medical student resilience. Student/advisor discrepancies may exemplify a cultural shift in Singapore's medical education climate, where students value increased individualism and autonomy in their education. As medical schools create interventions to enhance resilience and combat potential student burnout, they should consider individually-tailored as well as system-wide programs to best meet the needs of their students and faculty.

Is the relationship between affective temperament and resilience different in depression cases with and without childhood trauma?

PubMed

Gündoğar, Duru; Kesebir, Sermin; Demirkan, Arda Kazim; Yaylaci, Elif Tatlidil

2014-05-01

The aim of this study was to investigate if the relationship between affective temperament and resilience in major depression is different in cases with and without childhood trauma. For this purpose 100 cases with major depressive disorder (MDD) diagnosis according to DSM-IV were evaluated consecutively in their regular outpatient clinic follow-up interviews. Diagnostic interviews were done with SCID-I, affective temperament was evaluated with TEMPS-A (Evaluation of Temperament Memphis, Pisa, Paris and SanDiego-Autoquestionnaire) Temperament Questionnaire, resilience was evaluated with The Resilience Scale for Adults (RSA)-Turkish version. The presence of childhood trauma (CT) was determined by Early Trauma Inventory. In MDD cases without CT a correlation was present between psychological resilience and hyperthymic temperament, while there was a correlation between psychological resilience and depressive temperament in cases with CT. The relationship between depressive temperament and psychological resilience in cases with CT was observed in the perception of self, family cohesion, and social resources dimensions of psychological resilience. In depression cases with and without childhood trauma, the relationship between temperament and resilience appears to be different. According to our results psychological resilience was associated with hyperthymic temperament in depressive cases without childhood trauma, while it was associated with depressive temperament in depressive cases with childhood trauma. Copyright © 2014 Elsevier Inc. All rights reserved.

Use of Model-Based Design Methods for Enhancing Resiliency Analysis of Unmanned Aerial Vehicles

NASA Astrophysics Data System (ADS)

Knox, Lenora A.

The most common traditional non-functional requirement analysis is reliability. With systems becoming more complex, networked, and adaptive to environmental uncertainties, system resiliency has recently become the non-functional requirement analysis of choice. Analysis of system resiliency has challenges; which include, defining resilience for domain areas, identifying resilience metrics, determining resilience modeling strategies, and understanding how to best integrate the concepts of risk and reliability into resiliency. Formal methods that integrate all of these concepts do not currently exist in specific domain areas. Leveraging RAMSoS, a model-based reliability analysis methodology for Systems of Systems (SoS), we propose an extension that accounts for resiliency analysis through evaluation of mission performance, risk, and cost using multi-criteria decision-making (MCDM) modeling and design trade study variability modeling evaluation techniques. This proposed methodology, coined RAMSoS-RESIL, is applied to a case study in the multi-agent unmanned aerial vehicle (UAV) domain to investigate the potential benefits of a mission architecture where functionality to complete a mission is disseminated across multiple UAVs (distributed) opposed to being contained in a single UAV (monolithic). The case study based research demonstrates proof of concept for the proposed model-based technique and provides sufficient preliminary evidence to conclude which architectural design (distributed vs. monolithic) is most resilient based on insight into mission resilience performance, risk, and cost in addition to the traditional analysis of reliability.

Physical Resilience in Older Adults: Systematic Review and Development of an Emerging Construct.

PubMed

Whitson, Heather E; Duan-Porter, Wei; Schmader, Kenneth E; Morey, Miriam C; Cohen, Harvey J; Colón-Emeric, Cathleen S

2016-04-01

Resilience has been described in the psychosocial literature as the capacity to maintain or regain well-being during or after adversity. Physical resilience is a newer concept that is highly relevant to successful aging. Our objective was to characterize the emerging construct of resilience as it pertains to physical health in older adults, and to identify gaps and opportunities to advance research in this area. We conducted a systematic review to identify English language papers published through January 2015 that apply the term "resilience" in relation to physical health in older adults. We applied a modified framework analysis to characterize themes in implicit or explicit definitions of physical resilience. Of 1,078 abstracts identified, 49 articles met criteria for inclusion. Sixteen were letters or concept papers, and only one was an intervention study. Definitions of physical resilience spanned cellular to whole-person levels, incorporated many outcome measures, and represented three conceptual themes: resilience as a trait, trajectory, or characteristic/capacity. Current biomedical literature lacks consensus on how to define and measure physical resilience. We propose a working definition of physical resilience at the whole person level: a characteristic which determines one's ability to resist or recover from functional decline following health stressor(s). We present a conceptual framework that encompasses the related construct of physiologic reserve. We discuss gaps and opportunities in measurement, interactions across contributors to physical resilience, and points of intervention. Published by Oxford University Press on behalf of the Gerontological Society of America 2015.

Resilience to Urban Poverty: Theoretical and Empirical Considerations for Population Health

PubMed Central

Sanders, Anne E.; Lim, Sungwoo; Sohn, Woosung

2008-01-01

Objectives. To better understand the trajectory that propels people from poverty to poor health, we investigated health resilience longitudinally among African American families with incomes below 250% of the federal poverty level. Methods. Health resilience is the capacity to maintain good health in the face of significant adversity. With higher levels of tooth retention as a marker of health resilience, we used a social–epidemiological framework to define capacity for health resilience through a chain of determinants starting in the built environment (housing quality) and community context (social support) to familial influences (religiosity) and individual mental health and health behavior. Results. Odds of retaining 20 or more teeth were 3 times as likely among adults with resilience versus more-vulnerable adults (odds ratio=3.1; 95% confidence interval [CI]=1.3, 7.4). Children of caregivers with resilience had a lower incident rate of noncavitated tooth decay at 18- to 24-month follow-up (incidence risk ratio=0.8; 95% CI=0.7, 0.9) compared with other children. Conclusions. Health resilience to poverty was supported by protective factors in the built and social environments. When poverty itself cannot be eliminated, improving the quality of the built and social environments will foster resilience to its harmful health effects. PMID:18445798

Relationship between prenatal maternal stress and sleep quality in Chinese pregnant women: the mediation effect of resilience.

PubMed

Li, Guopeng; Kong, Linghua; Zhou, Haiyan; Kang, Xiaofei; Fang, Yueyan; Li, Ping

2016-09-01

To examine the relationship between prenatal maternal stress, resilience, and sleep quality, and to determine whether resilience plays a mediating role in the relationship between prenatal maternal stress and sleep quality among pregnant women. Two hundred and thirty-one pregnant women in their second trimester participated in the study. They completed questionnaires, including: the Pittsburgh Sleep Quality Index (PSQI), the Pregnancy Stress Rating Scale (PSRS), and the 10-item Connor-Davidson Resilience Scale (CD-RISC-10). A structural equation model was used to analyze the relationships among prenatal maternal stress, resilience, and sleep quality, with resilience as a mediator. Prenatal maternal stress was negatively associated with sleep quality in pregnant women (p < 0.01), whereas resilience was positively associated with sleep quality (p < 0.01). Furthermore, resilience mediated the relationship between prenatal maternal stress and sleep quality, and the mediation effect ratio was 22.0% (p < 0.01). The risk factor for disturbed sleep was pregnancy-specific stress; however, the protective factor for sleep quality was resilience. This finding could provide scientific evidence for the development of intervention strategies with which to improve sleep quality in pregnant women. Copyright © 2016 Elsevier B.V. All rights reserved.

A longitudinal pilot study of resilience in Canadian military personnel.

PubMed

Sudom, Kerry A; Lee, Jennifer E C; Zamorski, Mark A

2014-12-01

Research on psychological resilience is important for occupations involving routine exposure to trauma or critical events. Such research can allow for the identification of factors to target in training, education and intervention programs, as well as groups that may be at higher risk for mental health problems. Although efforts have been made to determine the individual characteristics that contribute to positive outcomes under stress, little is known about whether such characteristics are stable over time or how stressful events can impact psychological resilience in high-risk occupations such as military service. Following a review of the evidence on variations in resilience over time, results of a pilot study of Canadian Armed Forces personnel are presented in which differences in resilience characteristics were examined from military recruitment to several years after enrollment. While there was little change in resilience characteristics over time on average, there was considerable individual variation, with some individuals showing marked improvement and others showing marked deterioration in resilience characteristics. At both time points, individuals who had been deployed showed greater resilience characteristics than those who had never been deployed. Implications for the promotion of psychological resilience in military populations and personnel employed in other high-risk occupations are discussed. © 2014 John Wiley & Sons, Ltd.

Depression and resilience in women with HIV and early life stress: does trauma play a mediating role? A cross-sectional study.

PubMed

Spies, Georgina; Seedat, Soraya

2014-02-24

The present study sought to assess the relationship between depressive symptomatology and resilience among women infected with HIV and to investigate whether trauma exposure (childhood trauma, other discrete lifetime traumatic events) or the presence of post-traumatic stress symptomatology mediated this relationship. Cross-sectional study. Western Cape, South Africa. A convenience sample of 95 women infected with HIV in peri-urban communities in the Western Cape, South Africa. All women had exposure to moderate-to-severe childhood trauma as determined by the Childhood Trauma Questionnaire. We examined the relationship between depressive symptomatology and resilience (the Connor-Davidson Resilience Scale) and investigated whether trauma exposure or the presence of post-traumatic stress symptomatology mediated this relationship through the Sobel test for mediation and PLS path analysis. There was a significant negative correlation between depressive symptomatology and resilience (p=<0.01). PLS path analysis revealed a significant direct effect between depression and resilience. On the Sobel test for mediation, distal (childhood trauma) and proximal traumatic events did not significantly mediate this association (p=> 0.05). However, post-traumatic stress symptomatology significantly mediated the relationship between depression and resilience in trauma-exposed women living with HIV. In the present study, higher levels of resilience were associated with lower levels of self-reported depression. Although causal inferences are not possible, this suggests that in this sample, resilience may act as protective factor against the development of clinical depression. The results also indicate that post-traumatic stress symptoms (PTSS), which are highly prevalent in HIV-infected and trauma exposed individuals and often comorbid with depression, may further explain and account for this relationship. Further investigation is required to determine whether early identification and treatment of PTSS in this population may ameliorate the onset and persistence of major depression.

Depression and resilience in women with HIV and early life stress: does trauma play a mediating role? A cross-sectional study

PubMed Central

Spies, Georgina; Seedat, Soraya

2014-01-01

Objectives The present study sought to assess the relationship between depressive symptomatology and resilience among women infected with HIV and to investigate whether trauma exposure (childhood trauma, other discrete lifetime traumatic events) or the presence of post-traumatic stress symptomatology mediated this relationship. Design Cross-sectional study. Setting Western Cape, South Africa. Participants A convenience sample of 95 women infected with HIV in peri-urban communities in the Western Cape, South Africa. All women had exposure to moderate-to-severe childhood trauma as determined by the Childhood Trauma Questionnaire. Primary and secondary outcome measures We examined the relationship between depressive symptomatology and resilience (the Connor-Davidson Resilience Scale) and investigated whether trauma exposure or the presence of post-traumatic stress symptomatology mediated this relationship through the Sobel test for mediation and PLS path analysis. Results There was a significant negative correlation between depressive symptomatology and resilience (p=<0.01). PLS path analysis revealed a significant direct effect between depression and resilience. On the Sobel test for mediation, distal (childhood trauma) and proximal traumatic events did not significantly mediate this association (p=> 0.05). However, post-traumatic stress symptomatology significantly mediated the relationship between depression and resilience in trauma-exposed women living with HIV. Conclusions In the present study, higher levels of resilience were associated with lower levels of self-reported depression. Although causal inferences are not possible, this suggests that in this sample, resilience may act as protective factor against the development of clinical depression. The results also indicate that post-traumatic stress symptoms (PTSS), which are highly prevalent in HIV-infected and trauma exposed individuals and often comorbid with depression, may further explain and account for this relationship. Further investigation is required to determine whether early identification and treatment of PTSS in this population may ameliorate the onset and persistence of major depression. PMID:24566532

Spatial modelling of disaster resilience using infrastructure components of baseline resilience indicators for communities (BRIC) in special region of Yogyakarta

NASA Astrophysics Data System (ADS)

Kuscahyadi, Febriana; Meilano, Irwan; Riqqi, Akhmad

2017-07-01

Special Region of Yogyakarta Province (DIY) is one of Indonesian regions that often harmed by varied natural disasters which caused huge negative impacts. The most catastrophic one is earthquake in May, 27th 2006 with 6.3 magnitude moment [1], evoked 5716 people died, and economic losses for Rp. 29.1 Trillion, [2]. Their impacts could be minimized by committing disaster risk reduction program. Therefore, it is necessary to measure the natural disaster resilience within a region. Since infrastructure are might be able as facilities that means for evacuations, distribute supplies, and post disaster recovery [3], this research concerns to establish spatial modelling of natural disaster resilience using infrastructure components based on BRIC in DIY Province. There are three infrastructure used in this model; they are school, health facilities, and roads. Distance analysis is used to determine the level of resilient zone. The result gives the spatial understanding as a map that urban areas have better disaster resilience than the rural areas. The coastal areas and mountains areas which are vulnerable towards disaster have less resilience since there are no enough facilities that will increase the disaster resilience

Resilience, loneliness, and psychological distress among homeless youth.

PubMed

Perron, Jeff L; Cleverley, Kristin; Kidd, Sean A

2014-08-01

Extant quantitative research on loneliness among homeless youth has grouped loneliness with other elements of psychological distress. The current study seeks to determine if loneliness has a different relationship with resilience than does psychological distress among street youth. Using data from 47 participants, linear regression was conducted. Results indicate that homeless youth experiencing higher psychological distress reported lower resilience scores. However, levels of resilience are not significantly associated with feelings of loneliness when psychological distress was accounted for. This study has implications for how researchers and clinicians conceptualize and address feelings of loneliness among homeless youth. Copyright © 2014 Elsevier Inc. All rights reserved.

Measuring Young's Modulus the Easy Way, and Tracing the Effects of Measurement Uncertainties

ERIC Educational Resources Information Center

Nunn, John

2015-01-01

The speed of sound in a solid is determined by the density and elasticity of the material. Young's modulus can therefore be calculated once the density and the speed of sound in the solid are measured. The density can be measured relatively easily, and the speed of sound through a rod can be measured very inexpensively by setting up a longitudinal…

Approach To Development of Guidelines For Determination of Natural Attenuation Capacity and Resilience of Soils

NASA Astrophysics Data System (ADS)

Putters, B.

The natural attenuation capacity of the soil is often used to help remove contaminants from the soil and groundwater. However, the definition of natural attenuation capac- ity in terms of soil properties, and how it should be measured are still a matter of discussion. Moreover, due to the interaction between soil and pollutant during the attenuation processes, changes in soil properties may occur. The resilience of the soil determines the rate of recovery of the soil, and to what extent it regains its original capacity for attenuation. This resilience, too, is not yet defined or measureable. The objective of the research is to develop guidelines to determine the natural attenu- ation capacity and the resilience of soils. The approach comprises five steps: 1. Experimental data on degradation and adsorp- tion are collected from literature. Missing data are filled by means of regression tech- niques. 2. Based upon existing knowledge on fate and behaviour of pollutants in soil environment, data are analysed on expected relations between soil parameters: which parameters determine the processes. 3. The most important parameters are analysed in a sensitivity analysis, performed by means of a mechanistic model. The testing vari- ables in the sensitivity analysis are an expression of the natural attenuation capacity and the resilience, respectively, and will be related to time. 4. The sensitivity analy- sis is extended by development of an artificial neural network and by use of genetic algorithms. 5. Data from the realisations (model calculations with different input) are classified into guidelines.

The Consequences to National Security of Jurisdictional Gray Areas Between Emergency Management and Homeland Security

DTIC Science & Technology

2014-09-01

Security (DHS). This research explores how the determination, and more importantly, the urgency of the nation’s leaders to show resiliency , has created...2002 represented the blueprint for a nation of resiliency that unified the government and its community citizenry while deploying measures of...nation of pride and resiliency but also the owner of a complex inwardly focused, national security organization. To examine the JGAs between EM and HS

Resilience of aging populations after devastating earthquake event and its determinants - A case study of the Chi-Chi earthquake in Taiwan

NASA Astrophysics Data System (ADS)

Hung, Chih-Hsuan; Hung, Hung-Chih

2016-04-01

1.Background Major portions of urban areas in Asia are highly exposed and vulnerable to devastating earthquakes. Many studies identify ways to reduce earthquake risk by concentrating more on building resilience for the particularly vulnerable populations. By 2020, as the United Nations' warning, many Asian countries would become 'super-aged societies', such as Taiwan. However, local authorities rarely use resilience approach to frame earthquake disaster risk management and land use strategies. The empirically-based research about the resilience of aging populations has also received relatively little attention. Thus, a challenge arisen for decision-makers is how to enhance resilience of aging populations within the context of risk reduction. This study aims to improve the understanding of the resilience of aging populations and its changes over time in the aftermath of a destructive earthquake at the local level. A novel methodology is proposed to assess the resilience of aging populations and to characterize their changes of spatial distribution patterns, as well as to examine their determinants. 2.Methods and data An indicator-based assessment framework is constructed with the goal of identifying composite indicators (including before, during and after a disaster) that could serve as proxies for attributes of the resilience of aging populations. Using the recovery process of the Chi-Chi earthquake struck central Taiwan in 1999 as a case study, we applied a method combined a geographical information system (GIS)-based spatial statistics technique and cluster analysis to test the extent of which the resilience of aging populations is spatially autocorrelated throughout the central Taiwan, and to explain why clustering of resilient areas occurs in specific locations. Furthermore, to scrutinize the affecting factors of resilience, we develop an aging population resilience model (APRM) based on existing resilience theory. Using the APRM, we applied a multivariate regression analysis to identify and examine how various factors connect to the resilience of aging populations. To illustrate the proposed methodology, the study collected data on the resilience attributes, the disaster impacts and damages due to the Chi-Chi earthquake. The data were offered by the National Science and Technology Center for Disaster Reduction, Taiwan, as well as collected from the National Land Use Investigation, official census statistics and questionnaire surveys. 3.Results Integrating cluster analysis with GIS-based spatial statistical analysis, the resilience of aging populations were divided into five clusters of distribution patterns over the 10 years after the Chi-Chi earthquake. It shows that both population and elderly distributions were highly heterogeneous and spatial correlated across the study areas. We also demonstrated the 'hot spots' areas of the highly concentrated aging population across central Taiwan. Results of regression analysis disclosed the major factors that caused low resilience and changes of aging population distributions over time. These factors included the levels of seismic damage, infrastructure investments, as well as the land-use and socioeconomic attributes associated with the disaster areas. Finally, our findings provide stakeholders and policy-makers with better adaptive options to design and synthesize appropriate patchworks of planning measures for different types of resilience areas to reduce earthquake disaster risk.

Resilient moduli of typical Missouri soils and unbound granular base materials

DOT National Transportation Integrated Search

2008-03-01

The objective of this project is to accurately determine the resilient moduli for common Missouri subgrade soils and unbound granular base materials in accordance with the AASHTO T 307 test method. The test results included moduli data from 27 common...

Determinants of the process and outcomes of household participation in collaborative forest management in Ghana: a quantitative test of a community resilience model.

PubMed

Akamani, Kofi; Hall, Troy Elizabeth

2015-01-01

This study tested a proposed community resilience model by investigating the role of institutions, capital assets, community and socio-demographic variables as determinants of households' participation in Ghana's collaborative forest management (CFM) program and outcomes of the program. Quantitative survey data were gathered from 209 randomly selected households from two forest-dependent communities. Regression analysis shows that households' participation in the CFM program was predicted by community location, past connections with institutions, and past bonding social capital. Community location and past capitals were the strongest predictors of the outcomes of the CFM program as judged by current levels of capitals. Participation in the CFM program also had a positive effect on human capital but had minimal impact on the other capitals influencing household well-being and resilience, suggesting that the impact of co-management on household resilience may be modest. In all, the findings highlight the need for co-management policies to pay attention to the historical context of community interaction processes influencing access to capital assets and local institutions to successfully promote equitable resilience. Copyright © 2014 Elsevier Ltd. All rights reserved.

Inhibition of Staphylococcus epidermidis biofilms using polymerizable vancomycin derivatives.

PubMed

Lawson, McKinley C; Hoth, Kevin C; Deforest, Cole A; Bowman, Christopher N; Anseth, Kristi S

2010-08-01

Biofilm formation on indwelling medical devices is a ubiquitous problem causing considerable patient morbidity and mortality. In orthopaedic surgery, this problem is exacerbated by the large number and variety of material types that are implanted. Metallic hardware in conjunction with polymethylmethacrylate (PMMA) bone cement is commonly used. We asked whether polymerizable derivatives of vancomycin might be useful to (1) surface modify Ti-6Al-4V alloy and to surface/bulk modify PMMA bone cement to prevent Staphylococcus epidermidis biofilm formation and (2) whether the process altered the compressive modulus, yield strength, resilience, and/or fracture strength of cement copolymers. A Ti-6Al-4V alloy was silanized with methacryloxypropyltrimethoxysilane in preparation for subsequent polymer attachment. Surfaces were then coated with polymers formed from PEG(375)-acrylate or a vancomycin-PEG(3400)-PEG(375)-acrylate copolymer. PMMA was loaded with various species, including vancomycin and several polymerizable vancomycin derivatives. To assess antibiofilm properties of these materials, initial bacterial adherence to coated Ti-6Al-4V was determined by scanning electron microscopy (SEM). Biofilm dry mass was determined on PMMA coupons; the compressive mechanical properties were also determined. SEM showed the vancomycin-PEG(3400)-acrylate-type surface reduced adherent bacteria numbers by approximately fourfold when compared with PEG(375)-acrylate alone. Vancomycin-loading reduced all mechanical properties tested; in contrast, loading a vancomycin-acrylamide derivative restored these deficits but demonstrated no antibiofilm properties. A polymerizable, PEGylated vancomycin derivative reduced biofilm attachment but resulted in inferior cement mechanical properties. The approaches presented here may offer new strategies for developing biofilm-resistant orthopaedic materials. Specifically, polymerizable derivatives of traditional antibiotics may allow for direct polymerization into existing materials such as PMMA bone cement while minimizing mechanical property compromise. Questions remain regarding ideal monomer structure(s) that confer biologic and mechanical benefits.

Resilience in Caregivers of Partners With Young Onset Dementia: A Concept Analysis.

PubMed

Kobiske, Karie R; Bekhet, Abir K

2018-05-01

Over 200,000 Americans diagnosed with young onset dementia (YOD), dementia diagnosed prior to age 65, are cared for by family members. This can be costly to caregivers' physical and psychological health. Some adapt well to the caregiver role and are said to be resilient. Aim/Question: This paper builds on current understanding of the concept of resilience and applies this to caregivers of partners diagnosed with YOD. Concept analysis. Resilient caregivers exhibit attributes including determination, flexibility, positive thinking, self-efficacy, resourcefulness, social support and spirituality. YOD affects caregiver's health. Much research has been done on interventions for dementia caregivers. These interventions do not necessarily meet the needs of YOD caregivers as they do not account for dynamics in the family. By recognizing what is resiliency in YOD caregivers, interventions can be developed that focus on characteristics that build these attributes. Understanding the concept of resilience related to caregiving for a partner diagnosed with YOD allows for future development, measurement, and evaluation of nursing interventions. Nursing staff are in a strategic position to provide effective interventions to enhance resilience among caregivers of YOD.

Beyond Disaster Preparedness: Building a Resilience-Oriented Workforce for the Future

PubMed Central

Madrigano, Jaime; Chandra, Anita; Costigan, Tracy; Acosta, Joie D.

2017-01-01

Enhancing citizens’ and communities’ resilience is critical to adapt successfully to ongoing challenges faced by communities, as well as acute shocks resulting from disasters. While significant progress has been made in this area, several research and practice gaps remain. A crucial next step to advance resilience is the development of a resilience-oriented workforce. This narrative review examines existing literature to determine key components of a resilience-oriented workforce, with a focus on organizational structures, training and education, and leadership models. Reviewed articles spanned a variety of study types, including needs assessments of existing workforce, program evaluations, and reviews/commentaries. A resilience-oriented workforce spans many disciplines and training programs will need to reflect that. It requires a collaborative organizational model that promotes information sharing structures. Leadership models should foster a balance between workforce autonomy and operation as a collective entity. Optimal strategies to develop a resilience-oriented workforce have yet to be realized and future research will need to collect and synthesize data to promote and evaluate the growth of this field. PMID:29236028

Beyond Disaster Preparedness: Building a Resilience-Oriented Workforce for the Future.

PubMed

Madrigano, Jaime; Chandra, Anita; Costigan, Tracy; Acosta, Joie D

2017-12-13

Enhancing citizens' and communities' resilience is critical to adapt successfully to ongoing challenges faced by communities, as well as acute shocks resulting from disasters. While significant progress has been made in this area, several research and practice gaps remain. A crucial next step to advance resilience is the development of a resilience-oriented workforce. This narrative review examines existing literature to determine key components of a resilience-oriented workforce, with a focus on organizational structures, training and education, and leadership models. Reviewed articles spanned a variety of study types, including needs assessments of existing workforce, program evaluations, and reviews/commentaries. A resilience-oriented workforce spans many disciplines and training programs will need to reflect that. It requires a collaborative organizational model that promotes information sharing structures. Leadership models should foster a balance between workforce autonomy and operation as a collective entity. Optimal strategies to develop a resilience-oriented workforce have yet to be realized and future research will need to collect and synthesize data to promote and evaluate the growth of this field.

Physiological Trade-Offs Along a Fast-Slow Lifestyle Continuum in Fishes: What Do They Tell Us about Resistance and Resilience to Hypoxia?

PubMed

Stoffels, Rick J

2015-01-01

It has recently been suggested that general rules of change in ecological communities might be found through the development of functional relationships between species traits and performance. The physiological, behavioural and life-history traits of fishes are often organised along a fast-slow lifestyle continuum (FSLC). With respect to resistance (capacity for population to resist change) and resilience (capacity for population to recover from change) to environmental hypoxia, the literature suggests that traits enhancing resilience may come at the expense of traits promoting resistance to hypoxia; a trade-off may exist. Here I test whether three fishes occupying different positions along the FSLC trade-off resistance and resilience to environmental hypoxia. Static respirometry experiments were used to determine resistance, as measured by critical oxygen tension (Pcrit), and capacity for (RC) and magnitude of metabolic reduction (RM). Swimming respirometry experiments were used to determine aspects of resilience: critical (Ucrit) and optimal swimming speed (Uopt), and optimal cost of transport (COTopt). Results pertaining to metabolic reduction suggest a resistance gradient across species described by the inequality Melanotaenia fluviatilis (fast lifestyle) < Hypseleotris sp. (intermediate lifestyle) < Mogurnda adspersa (slow lifestyle). The Ucrit and COTopt data suggest a resilience gradient described by the reverse inequality, and so the experiments generally indicate that three fishes occupying different positions on the FSLC trade-off resistance and resilience to hypoxia. However, the scope of inferences that can be drawn from an individual study is narrow, and so steps towards general, trait-based rules of fish community change along environmental gradients are discussed.

Superelastic and pH-Responsive Degradable Dendrimer Cryogels Prepared by Cryo-aza-Michael Addition Reaction.

PubMed

Wang, Juan; Yang, Hu

2018-05-08

Dendrimers exhibit super atomistic features by virtue of their well-defined discrete quantized nanoscale structures. Here, we show that hyperbranched amine-terminated polyamidoamine (PAMAM) dendrimer G4.0 reacts with linear polyethylene glycol (PEG) diacrylate (575 g/mol) via the aza-Michael addition reaction at a subzero temperature (-20 °C), namely cryo-aza-Michael addition, to form a macroporous superelastic network, i.e., dendrimer cryogel. Dendrimer cryogels exhibit biologically relevant Young's modulus, high compression elasticity and super resilience at ambient temperature. Furthermore, the dendrimer cryogels exhibit excellent rebound performance and do not show significant stress relaxation under cyclic deformation over a wide temperature range (-80 to 100 °C). The obtained dendrimer cryogels are stable at acidic pH but degrade quickly at physiological pH through self-triggered degradation. Taken together, dendrimer cryogels represent a new class of scaffolds with properties suitable for biomedical applications.

A new titanium based alloy Ti-27Nb-13Zr produced by powder metallurgy with biomimetic coating for use as a biomaterial.

PubMed

Mendes, Marcio W D; Ágreda, Carola G; Bressiani, Ana H A; Bressiani, José C

2016-06-01

Titanium alloys are widely used in biomedical applications due to their excellent properties such as high strength, good corrosion resistance and biocompatibility. Titanium alloys with alloying elements such as Nb and Zr are biocompatible and have Young's modulus close to that of human bone. To increase the bioactivity of titanium alloy surfaces is used chemical treatment with NaOH followed by immersion in simulated body fluid (SBF). The purpose of this study was to produce the alloy Ti-27Nb-13Zr with low Young's modulus by powder metallurgy using powders produced by the HDH process. The formation of biomimetic coatings on samples immersed in SBF for 3, 7, 11 and 15 days was evaluated. Characterization of the coating was performed by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and scanning electron microscope. The microstructure and composition of the alloy were determined using SEM and XRD, while the mechanical properties were evaluated by determining the elastic modulus and the Vickers microhardness. The sintered alloys were composed of α and β phases, equiaxed grains and with density around 97.8% of its theoretical density. The Vickers microhardness and elasticity modulus of the alloy were determined and their values indicate that this alloy can be used as a biomaterial. Analysis of the coating revealed the presence of calcium phosphate layers on samples immersed for >3 days in the SBF solution. Copyright © 2016 Elsevier B.V. All rights reserved.

Effectiveness of Resilience Training on Ego-control and Hardiness of Illicit Drug Users.

PubMed

Roustaei, Amin; Bakhshipoor, Babollah; Doostian, Younes; Goodiny, Ali Akbar; Koohikar, Mansoureh; Massah, Omid

2017-01-01

The aim of this research was to determine the effectiveness of resilience training upon ego-control and hardiness of the addicted persons. This was a semi-experimental study with pretest and posttest control groups which was conducted in Sari, Iran, during 2014-2015. Thirty persons were selected among 240 illicit drug users who underwent screening. Resilience training was performed in ten sessions for the experimental group. The Kobasa hardiness questionnaire and self-restraint scale (SRS) were used for data collection and multivariate covariance test was performed for data analysis. According to the data, ego-control and hardiness of participants were improved significantly by resilience training (P < 0.001). Resilience training is effective upon the rate of ego-control and self-restraint and hardiness. This method can be used in addiction treatment clinics and residential centers.

Luchando y logrando/struggling and achieving: Resilience of Latina/o math and science teacher candidates at California Hispanic-Serving Institutions: A critical race perspective

NASA Astrophysics Data System (ADS)

Gonzalez, Laura

Latin math and science students represent a resilient, determined, and encouraging group of high achievers. This qualitative study presents the narratives of 10 Latin science and math teacher candidates currently attending Hispanic-Serving Institutions in California. Semi structured, in-depth interviews were conducted, where participants shared the challenges they experienced and the factors that contributed to their resilience. The Connor Davidson Resilience Scale CD-RISC was used to present resilience measures for each participant. This score is compared to a group of college students throughout the nation. The findings provide insight into the critical need for universities to examine institutional practices and efforts to support these high achievers who have already beaten tremendous odds by entering the halls of higher education.

Radion stabilization in higher curvature warped spacetime

NASA Astrophysics Data System (ADS)

Das, Ashmita; Mukherjee, Hiya; Paul, Tanmoy; SenGupta, Soumitra

2018-02-01

We consider a five dimensional AdS spacetime in presence of higher curvature term like F(R) = R + α R^2 in the bulk. In this model, we examine the possibility of modulus stabilization from the scalar degrees of freedom of higher curvature gravity free of ghosts. Our result reveals that the model stabilizes itself and the mechanism of modulus stabilization can be argued from a geometric point of view. We determine the region of the parametric space for which the modulus (or radion) can to be stabilized. We also show how the mass and coupling parameters of radion field are modified due to higher curvature term leading to modifications of its phenomenological implications on the visible 3-brane.

Defining disaster resilience: comparisons from key stakeholders involved in emergency management in Victoria, Australia.

PubMed

Goode, Natassia; Salmon, Paul M; Spencer, Caroline; McArdle, Dudley; Archer, Frank

2017-01-01

Three years after the introduction of the National Strategy for Disaster Resilience there remains no unanimously adopted definition of disaster resilience within Australia's emergency management sector. The aim of this study is to determine what the concept means to key stakeholders in the emergency management sector in the Australian State of Victoria, and how these conceptualisations overlap and diverge. Via an online survey, 113 people were asked how they define disaster resilience in their work in the emergency management sector. A data mining software tool, Leximancer, was employed to uncover the relationships between the definitions provided. The findings show that stakeholders see resilience as an 'ability' that encompasses emergency management activities and personal responsibility. However, the findings also highlight some possible points of conflict between stakeholders. In addition, the paper outlines and discusses a number of potential consequences for the implementation and the success of the resilience-based approach in Australia. © 2017 The Author(s). Disasters © Overseas Development Institute, 2017.

The potential use of physical resilience to predict healthy aging.

PubMed

Schorr, Anna; Carter, Christy; Ladiges, Warren

2018-01-01

Physical resilience is the ability of an organism to respond to stressors that acutely disrupt normal physiological homeostasis. By definition, resilience decreases with increasing age, while frailty, defined as a decline in tissue function, increases with increasing age. Assessment of resilience could therefore be an informative early paradigm to predict healthy aging compared to frailty, which measures late life dysfunction. Parameters for resilience in the laboratory mouse are not yet well defined, and no single standardized stress test exists. Since aging involves multiple genetic pathways, integrative responses involving multiple tissues, organs, and activities need to be measured to reveal the overall resilience status, suggesting a battery of stress tests, rather than a single all-encompassing one, would be most informative. Three simple, reliable, and inexpensive stressors are described in this review that could be used as a panel to determine levels of resilience. Brief cold water immersion allows a recovery time to normothermia as an indicator of resilience to hypothermia, i.e. the quicker the return to normal body temperature, the more robust the resilience. Sleep deprivation (SD) impairs remote memory in aged mice, and has detrimental effects on glucose metabolism. Cyclophosphamide (CYP) targets white blood cells, especially myeloid cells resulting in neutropenia with a rebound neutrophilia in an age-dependent manner. Thus a strong neutrophilic response indicates resilience. In conclusion, resilience promises to be an especially useful measurement of biological age, i.e. how fast a particular organ or tissue ages. The three stressors, cold, SD, and CYP, are applicable to human medicine and aging because they represent clinically relevant stress conditions that have effects in an age-dependent manner. They are thus an attractive perturbation for resilience testing in mice to measure the effectiveness of interventions that target basic aging processes.

Operationalizing ecological resilience at a landscape scale: A framework and case study from Silicon Valley

NASA Astrophysics Data System (ADS)

Beller, E.; Robinson, A.; Grossinger, R.; Grenier, L.; Davenport, A.

2015-12-01

Adaptation to climate change requires redesigning our landscapes and watersheds to maximize ecological resilience at large scales and integrated across urban areas, wildlands, and a diversity of ecosystem types. However, it can be difficult for environmental managers and designers to access, interpret, and apply resilience concepts at meaningful scales and across a range of settings. To address this gap, we produced a Landscape Resilience Framework that synthesizes the latest science on the qualitative mechanisms that drive resilience of ecological functions to climate change and other large-scale stressors. The framework is designed to help translate resilience science into actionable ecosystem conservation and restoration recommendations and adaptation strategies by providing a concise but comprehensive list of considerations that will help integrate resilience concepts into urban design, conservation planning, and natural resource management. The framework is composed of seven principles that represent core attributes which determine the resilience of ecological functions within a landscape. These principles are: setting, process, connectivity, redundancy, diversity/complexity, scale, and people. For each principle we identify several key operationalizable components that help illuminate specific recommendations and actions that are likely to contribute to landscape resilience for locally appropriate species, habitats, and biological processes. We are currently using the framework to develop landscape-scale recommendations for ecological resilience in the heavily urbanized Silicon Valley, California, in collaboration with local agencies, companies, and regional experts. The resilience framework is being applied across the valley, including urban, suburban, and wildland areas and terrestrial and aquatic ecosystems. Ultimately, the framework will underpin the development of strategies that can be implemented to bolster ecological resilience from a site to landscape scale.

Thermomechanical properties of polymeric materials and related stresses

NASA Technical Reports Server (NTRS)

Lee, Sheng Yen

1990-01-01

The thermomechanical properties of a number of widely used polymeric materials were determined by thermomechanical analysis and dynamic mechanical analysis. A combined profile of the coefficient of thermal expansion and the modulus change over a wide temperature range obtained by the analyses shows clearly the drastic effect of the glass transition on both the CTE and the modulus of a polymer, and the damaging potential due to such effect.

Inclusion of inhomogeneous deformation and strength characteristics in the problem on zonal disintegration of rocks

NASA Astrophysics Data System (ADS)

Chanyshev, AI; Belousova, OE

2018-03-01

The authors determine stress and deformation in a heterogeneous rock mass at the preset displacement and Cauchy stress vector at the boundary of an underground excavation. The influence of coordinates on Young’s modulus, shear modulus and ultimate strength is shown. It is found that regions of tension and compression alternate at the excavation boundary—i.e. zonal rock disintegration phenomenon is observed.

Osmotic swelling of polyacrylate hydrogels in physiological salt solutions.

PubMed

Horkay, F; Tasaki, I; Basser, P J

2000-01-01

The swelling behavior of fully neutralized sodium polyacrylate gels was investigated in aqueous solutions of alkali metal (LiCl, NaCl, KCl, CsCl) and alkaline earth metal salts (CaCl2, SrCl2, BaCl2). The total salt concentration and the ratio of monovalent to divalent cations were varied in the biologically significant range. It is found that the concentrations of both monovalent and divalent cations vary continuously and smoothly in the gel despite the abrupt change in the gel volume. The individual elastic, mixing, and ionic contributions to the free energy of the gel were separately determined as a function of the degree of network swelling to elucidate the thermodynamics of swelling. Shear modulus measurements performed at different Ca2+ concentrations suggest that Ca2+ does not form stable cross-links between the polymer chains. At low and moderate swelling ratios the concentration dependence of the shear modulus follows a power law behavior, G variation of phi n, with n = 0.34 +/- 0.03. At high swelling degrees, however, the shear modulus increases with increasing swelling. The value of the Flory-Huggins interaction parameter, chi, determined from osmotic swelling pressure and shear modulus measurements, strongly depends on the ionic composition of the equilibrium solution and increases with increasing Ca2+ concentration.

Combining AFM and Acoustic Probes to Reveal Changes in the Elastic Stiffness Tensor of Living Cells

PubMed Central

Nijenhuis, Nadja; Zhao, Xuegen; Carisey, Alex; Ballestrem, Christoph; Derby, Brian

2014-01-01

Knowledge of how the elastic stiffness of a cell affects its communication with its environment is of fundamental importance for the understanding of tissue integrity in health and disease. For stiffness measurements, it has been customary to quote a single parameter quantity, e.g., Young’s modulus, rather than the minimum of two terms of the stiffness tensor required by elasticity theory. In this study, we use two independent methods (acoustic microscopy and atomic force microscopy nanoindentation) to characterize the elastic properties of a cell and thus determine two independent elastic constants. This allows us to explore in detail how the mechanical properties of cells change in response to signaling pathways that are known to regulate the cell’s cytoskeleton. In particular, we demonstrate that altering the tensioning of actin filaments in NIH3T3 cells has a strong influence on the cell's shear modulus but leaves its bulk modulus unchanged. In contrast, altering the polymerization state of actin filaments influences bulk and shear modulus in a similar manner. In addition, we can use the data to directly determine the Poisson ratio of a cell and show that in all cases studied, it is less than, but very close to, 0.5 in value. PMID:25296302

Measurement of Young’s Modulus and Internal Damping of Pork Muscle in Dynamic Mode

NASA Astrophysics Data System (ADS)

Chakroun, Moez; Ghozlen, Med Hédi Ben

2016-09-01

Automotive shocks involve various tiers’ speed for different human body tissues. Knowing the behavior of these tissues, including muscles, in different vibration frequency is therefore necessary. The muscle has viscoelatic properties. Dynamically, this material has variable mechanical properties depending on the vibration frequency. A novel technique is being employed to examine the variation of the mechanical impedance of pork muscle as a function of frequency. A force is imposed on the lower surface of the sample and acceleration is measured on its upper surface. These two parameters are measured using sensors. The sample is modeled by Kelvin-Voigt model. These measures allow deducing the change in the mechanical impedance modulus (/Zexp/ = /Force: Acceleration/) of pork muscle as a function of vibration frequency. The measured impedance has a resonance of approximately 60Hz. Best-fit parameters of theoretical impedance can be deduced by superposition with the experiment result. The variation of Young’s modulus and internal damping of pig’s muscle as a function of frequency are determined. The results obtained between 5Hz and 30Hz are the same as determined by Aimedieu and al in 2003, therefore validating our technique. The Young’s modulus of muscle increases with the frequency, on the other hand, we note a rating decrease of internal damping.

The effect of magnesium ion concentration on the fibrocartilage regeneration potential of goat costal chondrocytes.

PubMed

Hagandora, Catherine K; Tudares, Mauro A; Almarza, Alejandro J

2012-03-01

Magnesium has recently been explored as a potential biomaterial for degradable orthopedic implants but its effect on fibrocartilage remains unknown. The objective of this study was to assess the effect of high concentrations of magnesium ions on the matrix production of goat costal fibrochondrocytes in vitro. Cells were cultured using a scaffoldless approach with media containing magnesium chloride (MgCl(2)) or magnesium sulfate (MgSO(4)) at concentrations of 20, 50, and 100 mM in addition to the baseline magnesium concentration of 0.8 mM MgSO(4). At 4 weeks, there were no significant differences in compressive tangent modulus and total matrix production between constructs cultured in 20 mM Mg(2+) and the 0.8 mM Mg(2+) control (435 ± 47 kPa). There was a significant decrease in compressive tangent modulus compared to the 0.8 mM Mg(2+) constructs in the 50 mM MgCl(2) and MgSO(4) groups, while the 100 mM groups were not mechanically testable (p < 0.05). The collagen and glycosaminoglycan (GAG) content of the 50 and 100 mM MgCl(2) and MgSO(4) constructs was significantly lower than the control (6.9 ± 0.5% and 16.5 ± 1.3% per dry weight, respectively) (p < 0.05). The results show that goat costal fibrochondrocytes exhibit a high degree of resiliency to magnesium ion concentrations up to 20 mM in vitro.

Launch Load Resistant Spacecraft Mechanism Bearings Made From NiTi Superelastic Intermetallic Materials

NASA Technical Reports Server (NTRS)

DellaCorte, Christopher; Moore, Lewis E., III

2014-01-01

Compared to conventional bearing materials (tool steel and ceramics), emerging Superelastic Intermetallic Materials (SIMs), such as 60NiTi, have significantly lower elastic modulus and enhanced strain capability. They are also immune to atmospheric corrosion (rusting). This offers the potential for increased resilience and superior ability to withstand static indentation load without damage. In this paper, the static load capacity of hardened 60NiTi 50-mm-bore ball bearing races are measured to correlate existing flat-plate indentation load capacity data to an actual bearing geometry through the Hertz stress relations. The results confirmed the validity of using the Hertz stress relations to model 60NiTi contacts; 60NiTi exhibits a static stress capability (approximately 3.1 GPa) between that of 440C (2.4 GPa) and REX20 (3.8 GPa) tool steel. When the reduced modulus and extended strain capability are taken into account, 60NiTi is shown to withstand higher loads than other bearing materials. To quantify this effect, a notional space mechanism, a 5-kg mass reaction wheel, was modeled with respect to launch load capability when supported on standard (catalogue geometry) design 440C; 60NiTi and REX20 tool steel bearings. For this application, the use of REX20 bearings increased the static load capability of the mechanism by a factor of three while the use of 60NiTi bearings resulted in an order of magnitude improvement compared to the baseline 440C stainless steel bearings

Launch Load Resistant Spacecraft Mechanism Bearings Made From NiTi Superelastic Intermetallic Materials

NASA Technical Reports Server (NTRS)

Dellacorte, Christopher; Moore, Lewis E.

2014-01-01

Compared to conventional bearing materials (tool steel and ceramics), emerging Superelastic Intermetallic Materials (SIMs), such as 60NiTi, have significantly lower elastic modulus and enhanced strain capability. They are also immune to atmospheric corrosion (rusting). This offers the potential for increased resilience and superior ability to withstand static indentation load without damage. In this paper, the static load capacity of hardened 60NiTi 50mm bore ball-bearing races are measured to correlate existing flat-plate indentation load capacity data to an actual bearing geometry through the Hertz stress relations. The results confirmed the validity of using the Hertz stress relations to model 60NiTi contacts; 60NiTi exhibits a static stress capability (3.1GPa) between that of 440C (2.4GPa) and REX20 (3.8GPa) tool steel. When the reduced modulus and extended strain capability are taken into account, 60NiTi is shown to withstand higher loads than other bearing materials. To quantify this effect, a notional space mechanism, a 5kg mass reaction wheel, was modeled with respect to launch load capability when supported on 440C, 60NiTi and REX20 tool steel bearings. For this application, the use of REX20 bearings increased the static load capability of the mechanism by a factor of three while the use of 60NiTi bearings resulted in an order of magnitude improvement compared to the baseline 440C stainless steel bearings.

[Mediator effect of resilience between burnout and health in nursing staff].

PubMed

Arrogante, Óscar

2014-01-01

To determine the relationships between 3 burnout dimensions (Emotional Exhaustion, Depersonalization, and Reduced Personal Accomplishment), health (physical and mental health), and resilience, as well as to analyse the mediator role of resilience in relationships between burnout and health in a sample of Nursing staff. A correlational and cross-sectional study with probabilistic sampling was conducted on a sample of 194 Nursing staff of University Hospital of Fuenlabrada (Madrid), and composed of nurses (n=133) and nursing assistants (n=61). MBI-HSS (burnout syndrome), SF-12v1 (physical and mental components of health), 10-Item CD-RISC (resilience), and sociodemographic variables. Correlational analyses showed that mental health was negatively related with 3 burnout dimensions and positively with resilience. Furthermore, physical health was only negatively related with Emotional Exhaustion, and positively with resilience. Mediational analyses revealed that resilience mediated, on one hand, the relationship between Emotional Exhaustion and Depersonalization with mental health (partial mediation) and, on the other hand, the relationship between Reduced Personal Accomplishment and mental health (total mediation). Resilience is not only important to improve the mental health of Nursing staff, but also to buffer and minimize the negative consequences of the occupational stress to which they are at risk, with its most adverse result being signs of burnout. Therefore, resilience training should be promoted to improve nursing clinical practice. Copyright © 2014 Elsevier España, S.L.U. All rights reserved.

Bouncing Back: Resilience and Mastery Among HIV-Positive Older Gay and Bisexual Men.

PubMed

Emlet, Charles A; Shiu, Chengshi; Kim, Hyun-Jun; Fredriksen-Goldsen, Karen

2017-02-01

Adults with HIV infection are living into old age. It is critical we investigate positive constructs such as resilience and mastery to determine factors associated with psychological well-being. We examine HIV-related factors, adverse conditions, and psychosocial characteristics that are associated with resilience (the ability to bounce back) and mastery (sense of self-efficacy). We analyzed 2014 data from the longitudinal study Aging with Pride: National Health, Aging, and Sexuality/Gender Study (NHAS), focusing on a subsample of 335 gay and bisexual older men. Multivariate linear regression was used to identify factors that contributed or detracted from resilience and mastery in the sample recruited from 17 sites from across the United States. Resilience and mastery were independently associated with psychological health-related quality of life. In multivariate analysis, adjusting for demographic characteristics, previous diagnosis of depression was negatively associated with resilience. Time since HIV diagnosis was positively associated with mastery whereas victimization was negatively associated with mastery. Social support and community engagement were positively associated with both resilience and mastery. Individual and structural-environmental characteristics contributed to resilience and mastery. These findings can be used to develop interventions incorporating an increased understanding of factors that are associated with both resilience and mastery. © The Author 2017. 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.

Mean annual precipitation predicts primary production resistance and resilience to extreme drought

DOE PAGES

Stuart-Haëntjens, Ellen; De Boeck, Hans J.; Lemoine, Nathan P.; ...

2018-09-01

Extreme drought is increasing in frequency and intensity in many regions globally, with uncertain consequences for the resistance and resilience of ecosystem functions, including primary production. Primary production resistance, the capacity to withstand change during extreme drought, and resilience, the degree to which production recovers, vary among and within ecosystem types, obscuring generalized patterns of ecological stability. Theory and many observations suggest forest production is more resistant but less resilient than grassland production to extreme drought; however, studies of production sensitivity to precipitation variability indicate that the processes controlling resistance and resilience may be influenced more by mean annual precipitationmore » (MAP) than ecosystem type. Here, we conducted a global meta-analysis to investigate primary production resistance and resilience to extreme drought in 64 forests and grasslands across a broad MAP gradient. We found resistance to extreme drought was predicted by MAP; however, grasslands (positive) and forests (negative) exhibited opposing resilience relationships with MAP. Our findings indicate that common plant physiological mechanisms may determine grassland and forest resistance to extreme drought, whereas differences among plant residents in turnover time, plant architecture, and drought adaptive strategies likely underlie divergent resilience patterns. The low resistance and resilience of dry grasslands suggests that these ecosystems are the most vulnerable to extreme drought – a vulnerability that is expected to compound as extreme drought frequency increases in the future.« less

[The impact of stress and personality on resilience of patients with ulcerative colitis].

PubMed

Liu, W; Wang, J; Wang, H; Chen, X Y; Li, J S

2018-02-01

Objective: To study relevant factors that influence psychological resilience in patients with ulcerative colitis(UC), especially the role of perceived stress and personality. Methods: Patients with UC were recruited from January 2015 to December 2016 in the First Hospital of Zhengzhou University. Education levels, income, duration of disease, Mayo score and disease phenotype according to Montreal classification were collected. Resilience was measured using Connor-Davidson resilience scale (CD-RISC). Perceived stress was measured by perceived stress scale (PSS). Personality was evaluated using Eysenck personality questionnaire (EPQ). Univariate analyses were conducted to determine the correlation of variables with resilience and thereafter those statistically significant were reanalyzed via a multivariate regression model. Results: A total of 188 patients with UC were finally recruited. Univariate analyses demonstrated resilience was inversely associated with perceived stress, Mayo score and neuroticism. Extraversion, income, college education were positively related to resilience. However, multivariate analyses revealed that perceived stress( OR= 0.901, 95% CI 0.833-0.975), extraversion ( OR= 1.257, 95% CI 1.087-1.454), neuroticism ( OR= 0.818, 95% CI 0.679-0.985), Mayo score ( OR= 0.856, 95% CI 0.742-0.988) and income ( OR= 6.411, 95% CI 2.136-9.244) were significantly related to resilience. Conclusions: Resilience of UC patients is not only associated with disease activity, but also with personality, perceived stress and income.

Mean annual precipitation predicts primary production resistance and resilience to extreme drought.

PubMed

Stuart-Haëntjens, Ellen; De Boeck, Hans J; Lemoine, Nathan P; Mänd, Pille; Kröel-Dulay, György; Schmidt, Inger K; Jentsch, Anke; Stampfli, Andreas; Anderegg, William R L; Bahn, Michael; Kreyling, Juergen; Wohlgemuth, Thomas; Lloret, Francisco; Classen, Aimée T; Gough, Christopher M; Smith, Melinda D

2018-04-27

Extreme drought is increasing in frequency and intensity in many regions globally, with uncertain consequences for the resistance and resilience of ecosystem functions, including primary production. Primary production resistance, the capacity to withstand change during extreme drought, and resilience, the degree to which production recovers, vary among and within ecosystem types, obscuring generalized patterns of ecological stability. Theory and many observations suggest forest production is more resistant but less resilient than grassland production to extreme drought; however, studies of production sensitivity to precipitation variability indicate that the processes controlling resistance and resilience may be influenced more by mean annual precipitation (MAP) than ecosystem type. Here, we conducted a global meta-analysis to investigate primary production resistance and resilience to extreme drought in 64 forests and grasslands across a broad MAP gradient. We found resistance to extreme drought was predicted by MAP; however, grasslands (positive) and forests (negative) exhibited opposing resilience relationships with MAP. Our findings indicate that common plant physiological mechanisms may determine grassland and forest resistance to extreme drought, whereas differences among plant residents in turnover time, plant architecture, and drought adaptive strategies likely underlie divergent resilience patterns. The low resistance and resilience of dry grasslands suggests that these ecosystems are the most vulnerable to extreme drought - a vulnerability that is expected to compound as extreme drought frequency increases in the future. Copyright © 2018. Published by Elsevier B.V.

Mean annual precipitation predicts primary production resistance and resilience to extreme drought

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stuart-Haëntjens, Ellen; De Boeck, Hans J.; Lemoine, Nathan P.

Extreme drought is increasing in frequency and intensity in many regions globally, with uncertain consequences for the resistance and resilience of ecosystem functions, including primary production. Primary production resistance, the capacity to withstand change during extreme drought, and resilience, the degree to which production recovers, vary among and within ecosystem types, obscuring generalized patterns of ecological stability. Theory and many observations suggest forest production is more resistant but less resilient than grassland production to extreme drought; however, studies of production sensitivity to precipitation variability indicate that the processes controlling resistance and resilience may be influenced more by mean annual precipitationmore » (MAP) than ecosystem type. Here, we conducted a global meta-analysis to investigate primary production resistance and resilience to extreme drought in 64 forests and grasslands across a broad MAP gradient. We found resistance to extreme drought was predicted by MAP; however, grasslands (positive) and forests (negative) exhibited opposing resilience relationships with MAP. Our findings indicate that common plant physiological mechanisms may determine grassland and forest resistance to extreme drought, whereas differences among plant residents in turnover time, plant architecture, and drought adaptive strategies likely underlie divergent resilience patterns. The low resistance and resilience of dry grasslands suggests that these ecosystems are the most vulnerable to extreme drought – a vulnerability that is expected to compound as extreme drought frequency increases in the future.« less

Resilience and the rehabilitation of adult spinal cord injury survivors: A qualitative systematic review.

PubMed

Kornhaber, Rachel; Mclean, Loyola; Betihavas, Vasiliki; Cleary, Michelle

2018-01-01

To synthesize the qualitative research evidence that explored how survivors of adult spinal cord injury experience and make sense of resilience. Spinal cord injury is often a sudden and unexpected life-changing event requiring complex and long-term rehabilitation. The development of resilience is essential in determining how spinal cord injury survivors negotiate this injury and rehabilitation. A qualitative systematic review and thematic synthesis of the research evidence. CINAHL, PubMed, Embase, Scopus and PsycINFO were searched, no restriction dates were used. Methodological quality was assessed using the Critical Appraisal Skills Programme checklist. Thematic synthesis focused on how survivors of adult spinal cord injury experience and make sense of resilience. Six qualitative research articles reported the experiences of 84 spinal cord injury survivors. Themes identified were: uncertainty and regaining independence; prior experiences of resilience; adopting resilient thinking; and strengthening resilience through supports. Recovery and rehabilitation following spinal cord survivors is influenced by the individual's capacity for resilience. Resilience may be influenced by previous life experiences and enhanced by supportive nursing staff encouraging self-efficacy. Survivors identified the need for active involvement in decision-making about their care to enable a sense of regaining control of their lives. This has the potential to have a significant impact on their self-efficacy and in turn health outcomes. © 2017 John Wiley & Sons Ltd.

Simple display system of mechanical properties of cells and their dispersion.

PubMed

Shimizu, Yuji; Kihara, Takanori; Haghparast, Seyed Mohammad Ali; Yuba, Shunsuke; Miyake, Jun

2012-01-01

The mechanical properties of cells are unique indicators of their states and functions. Though, it is difficult to recognize the degrees of mechanical properties, due to small size of the cell and broad distribution of the mechanical properties. Here, we developed a simple virtual reality system for presenting the mechanical properties of cells and their dispersion using a haptic device and a PC. This system simulates atomic force microscopy (AFM) nanoindentation experiments for floating cells in virtual environments. An operator can virtually position the AFM spherical probe over a round cell with the haptic handle on the PC monitor and feel the force interaction. The Young's modulus of mesenchymal stem cells and HEK293 cells in the floating state was measured by AFM. The distribution of the Young's modulus of these cells was broad, and the distribution complied with a log-normal pattern. To represent the mechanical properties together with the cell variance, we used log-normal distribution-dependent random number determined by the mode and variance values of the Young's modulus of these cells. The represented Young's modulus was determined for each touching event of the probe surface and the cell object, and the haptic device-generating force was calculated using a Hertz model corresponding to the indentation depth and the fixed Young's modulus value. Using this system, we can feel the mechanical properties and their dispersion in each cell type in real time. This system will help us not only recognize the degrees of mechanical properties of diverse cells but also share them with others.

Simple Display System of Mechanical Properties of Cells and Their Dispersion

PubMed Central

Shimizu, Yuji; Kihara, Takanori; Haghparast, Seyed Mohammad Ali; Yuba, Shunsuke; Miyake, Jun

2012-01-01

The mechanical properties of cells are unique indicators of their states and functions. Though, it is difficult to recognize the degrees of mechanical properties, due to small size of the cell and broad distribution of the mechanical properties. Here, we developed a simple virtual reality system for presenting the mechanical properties of cells and their dispersion using a haptic device and a PC. This system simulates atomic force microscopy (AFM) nanoindentation experiments for floating cells in virtual environments. An operator can virtually position the AFM spherical probe over a round cell with the haptic handle on the PC monitor and feel the force interaction. The Young's modulus of mesenchymal stem cells and HEK293 cells in the floating state was measured by AFM. The distribution of the Young's modulus of these cells was broad, and the distribution complied with a log-normal pattern. To represent the mechanical properties together with the cell variance, we used log-normal distribution-dependent random number determined by the mode and variance values of the Young's modulus of these cells. The represented Young's modulus was determined for each touching event of the probe surface and the cell object, and the haptic device-generating force was calculated using a Hertz model corresponding to the indentation depth and the fixed Young's modulus value. Using this system, we can feel the mechanical properties and their dispersion in each cell type in real time. This system will help us not only recognize the degrees of mechanical properties of diverse cells but also share them with others. PMID:22479595

Spatial resilience of forested landscapes under climate change and management

Treesearch

Melissa S. Lucash; Robert M. Scheller; Eric J. Gustafson; Brian R. Sturtevant

2017-01-01

Context Resilience, the ability to recover from disturbance, has risen to the forefront of scientific policy, but is difficult to quantify, particularly in large, forested landscapes subject to disturbances, management, and climate change. Objectives Our objective was to determine which spatial drivers will control landscape...

"K" value correlation study.

DOT National Transportation Integrated Search

1972-08-01

One objective of this study was to determine what correlation existed between the modulus of subgrade reaction as determined by the Plate Bearing Test and the deflection determined by the first snsor of the Lane Wells "Dynaflect". The Research and De...

Determination of Elastic Moduli of Fiber-Resin Composites Using an Impulse Excitation Technique

NASA Technical Reports Server (NTRS)

Viens, Michael J.; Johnson, Jeffrey J.

1996-01-01

The elastic moduli of graphite/epoxy and graphite/cyanate ester composite specimens with various laminate lay-ups was determined using an impulse excitation/acoustic resonance technique and compared to those determined using traditional strain gauge and extensometer techniques. The stiffness results were also compared to those predicted from laminate theory using uniaxial properties. The specimen stiffnesses interrogated ranged from 12 to 30 Msi. The impulse excitation technique was found to be a relatively quick and accurate method for determining elastic moduli with minimal specimen preparation and no requirement for mechanical loading frames. The results of this investigation showed good correlation between the elastic modulus determined using the impulse excitation technique, strain gauge and extensometer techniques, and modulus predicted from laminate theory. The flexural stiffness determined using the impulse excitation was in good agreement with that predicted from laminate theory. The impulse excitation/acoustic resonance interrogation technique has potential as a quality control test.

Type D personality and post-traumatic stress disorder symptoms among intensive care unit nurses: The mediating effect of resilience.

PubMed

Cho, Geum-Jin; Kang, Jiyeon

2017-01-01

The purpose of this study was to investigate the relationship between Type D personality and post-traumatic stress disorder (PTSD) symptoms of intensive care unit (ICU) nurses and to determine the mediating effect of resilience on this relationship. A cross-sectional survey was performed with 179 ICU nurses from 7 hospitals in Gyeong-Nam province, South Korea. The Type D personality, resilience, and PTSD symptoms of subjects were measured using a self-report questionnaire. The mediating effect was analyzed by a series of hierarchical multiple regressions. A total of 38.6% of the study participants turned out to have Type D personality. The Type D personality was positively correlated with PTSD symptoms, and negatively correlated with resilience. There was a negative correlation between resilience and PTSD symptoms. The indirect effect of Type D personality on PTSD symptoms via resilience (β = .51, p < .001) was smaller than the direct effect (β = .58, p < .001). Based on the above results, it can be concluded that resilience had a partial mediating effect on the relationship between Type D personality and PTSD symptoms of ICU nurses. Further studies need to be done to develop interventions for enhancing resilience in ICU nurses.

High pressure phase transformation in uranium carbide: A first principle study

NASA Astrophysics Data System (ADS)

Sahoo, B. D.; Joshi, K. D.; Gupta, Satish C.

2013-02-01

First principles calculations have been carried out to analyze structural, elastic and dynamic stability, of UC under hydrostatic compression. The comparison of enthalpies of rocksalt type (B1) and body centered orthorhombic (bco) structures as a function of pressure suggests the B1 →bco transition at ˜ 23 GPa, in good agreement with experimental value of 27 GPa. From the lattice dynamic calculations we have determined the phonon dispersion relations for B1 phase at various compressions. It is found that TA phonon branch along Γ-X direction becomes imaginary around the transition pressure. Further, the phonon instability so caused is of long wavelength nature as it occurs near the Brillouin zone centre. This long wavelength phonon instability at the transition point indicates that the B1 →bco transition is driven by elastic failure (the vanishing of C44 modulus). Various physical quantities such as equilibrium volume, bulk modulus, pressure derivative of bulk modulus and elastic constants have been determined at zero pressure and compared with data available in literature.

Effect of Elastin Digestion on the Quasi-static Tensile Response of Medial Collateral Ligament

PubMed Central

Henninger, Heath B.; Underwood, Clayton J.; Romney, Steven J.; Davis, Grant L.; Weiss, Jeffrey A.

2014-01-01

Elastin is a structural protein that provides resilience to biological tissues. We examined the contributions of elastin to the quasi-static tensile response of porcine medial collateral ligament through targeted disruption of the elastin network with pancreatic elastase. Elastase concentration and treatment time were varied to determine a dose response. Whereas elastin content decreased with increasing elastase concentration and treatment time, the change in peak stress after cyclic loading reached a plateau above 1 U/ml elastase and 6 hr treatment. For specimens treated with 2 U/ml elastase for 6 hr, elastin content decreased approximately 35%. Mean peak tissue strain after cyclic loading (4.8%, p≥0.300), modulus (275 MPa, p≥0.114) and hysteresis (20%, p≥0.553) were unaffected by elastase digestion, but stress decreased significantly after treatment (up to 2 MPa, p≤0.049). Elastin degradation had no effect on failure properties, but tissue lengthened under the same pre-stress. Stiffness in the linear region was unaffected by elastase digestion, suggesting that enzyme treatment did not disrupt collagen. These results demonstrate that elastin primarily functions in the toe region of the stress-strain curve, yet contributes load support in the linear region. The increase in length after elastase digestion suggests that elastin may pre-stress and stabilize collagen crimp in ligaments. PMID:23553827

Determination of correlation between backflow volume and mitral valve leaflet young modulus from two dimensional echocardiogram images

NASA Astrophysics Data System (ADS)

Jong, Rudiyanto P.; Osman, Kahar; Adib, M. Azrul Hisham M.

2012-06-01

Mitral valve prolapse without proper monitoring might lead to a severe mitral valve failure which eventually leads to a sudden death. Additional information on the mitral valve leaflet condition against the backflow volume would be an added advantage to the medical practitioner for their decision on the patients' treatment. A study on two dimensional echocardiography images has been conducted and the correlations between the backflow volume of the mitral regurgitation and mitral valve leaflet Young modulus have been obtained. Echocardiogram images were analyzed on the aspect of backflow volume percentage and mitral valve leaflet dimensions on different rates of backflow volume. Young modulus values for the mitral valve leaflet were obtained by using the principle of elastic deflection and deformation on the mitral valve leaflet. The results show that the backflow volume increased with the decrease of the mitral valve leaflet Young modulus which also indicate the condition of the mitral valve leaflet approaching failure at high backflow volumes. Mitral valve leaflet Young modulus values obtained in this study agreed with the healthy mitral valve leaflet Young modulus from the literature. This is an initial overview of the trend on the prediction of the behaviour between the fluid and the structure of the blood and the mitral valve which is extendable to a larger system of prediction on the mitral valve leaflet condition based on the available echocardiogram images.

Nanostructure and elastic modulus of single trabecula in bovine cancellous bone.

PubMed

Yamada, Satoshi; Tadano, Shigeru; Fukuda, Sakurako

2014-11-07

We aimed to investigate the elastic modulus of trabeculae using tensile tests and assess the effects of nanostructure at the hydroxyapatite (HAp) crystal scale on the elastic modulus. In the experiments, 18 trabeculae that were at least 3mm in length in the proximal epiphysis of three adult bovine femurs were used. Tensile tests were conducted using a small tensile testing device coupled with microscopy under air-dried condition. The c-axis orientation of HAp crystals and the degree of orientation were measured by X-ray diffraction. To observe the deformation behavior of HAp crystals under tensile loading, the same tensile tests were conducted in X-ray diffraction measurements. The mineral content of specimens was evaluated using energy dispersive X-ray spectrometry. The elastic modulus of a single trabecula varied from 4.5 to 23.6 GPa, and the average was 11.5 ± 5.0 GPa. The c-axis of HAp crystals was aligned with the trabecular axis and the crystals were lineally deformed under tensile loading. The ratio of the HAp crystal strain to the tissue strain (strain ratio) had a significant correlation with the elastic modulus (r=0.79; P<0.001). However, the mineral content and the degree of orientation did not vary widely and did not correlate with the elastic modulus in this study. It suggests that the strain ratio may represent the nanostructure of a single trabecula and would determine the elastic modulus as well as mineral content and orientation. Copyright © 2014 Elsevier Ltd. All rights reserved.

Improving the estimate of the effective elastic modulus derived from three-point bending tests of long bones.

PubMed

Kourtis, Lampros C; Carter, Dennis R; Beaupre, Gary S

2014-08-01

Three-point bending tests are often used to determine the apparent or effective elastic modulus of long bones. The use of beam theory equations to interpret such tests can result in a substantial underestimation of the true effective modulus. In this study three-dimensional, nonlinear finite element analysis is used to quantify the errors inherent in beam theory and to create plots that can be used to correct the elastic modulus calculated from beam theory. Correction plots are generated for long bones representative of a variety of species commonly used in research studies. For a long bone with dimensions comparable to the mouse femur, the majority of the error in the effective elastic modulus results from deformations to the bone cross section that are not accounted for in the equations from beam theory. In some cases, the effective modulus calculated from beam theory can be less than one-third of the true effective modulus. Errors are larger: (1) for bones having short spans relative to bone length; (2) for bones with thin vs. thick cortices relative to periosteal diameter; and (3) when using a small radius or "knife-edge" geometry for the center loading ram and the outer supports in the three-point testing system. The use of these correction plots will enable researchers to compare results for long bones from different animal strains and to compare results obtained using testing systems that differ with regard to length between the outer supports and the radius used for the loading ram and outer supports.

Shear weakening for different lithologies observed at different saturation stages

NASA Astrophysics Data System (ADS)

Diethart-Jauk, Elisabeth; Gegenhuber, Nina

2018-01-01

For this study, samples from different lithologies ("Leitha"-limestone, "Dachstein"-limestone, "Haupt"-dolomite, "Bunt"-sandstone, Grey Berea sandstone, granite, quartzite and basalt) were selected. Samples were dried at 70 °C, respectively 105 °C and were saturated with brine. Mass, porosity, permeability, compressional and shear wave velocity were determined from dry and brine saturated samples at laboratory conditions, based on an individual measurement program. Shear modulus was calculated to find out, if shear weakening exists for the dataset. Shear weakening means that shear modulus of dry samples is higher than of saturated samples, but it is assumed that shear modulus is unaffected by saturation. "Dachstein"-limestone and basalt show shear weakening, quartzite samples show both weakening and hardening. Granite samples are affected by temperature, after drying with 105 °C no change can be observed anymore. "Bunt"-sandstone samples show a change in the shear modulus in a small extent, although they may contain clay minerals. The other lithologies show no effect. Explanations for carbonate samples can be the complicated pore structure, for basalt it could be that weathering creates clay minerals which are known as causes for a change of the shear modulus. Fluid viscosity can also be an important factor.

Frequency characteristics of vibration generated by dual acoustic radiation force for estimating viscoelastic properties of biological tissues

NASA Astrophysics Data System (ADS)

Watanabe, Ryoichi; Arakawa, Mototaka; Kanai, Hiroshi

2018-07-01

We proposed a new method for estimating the viscoelastic property of the local region of a sample. The viscoelastic parameters of the phantoms simulating the biological tissues were quantitatively estimated by analyzing the frequency characteristics of displacement generated by acoustic excitation. The samples were locally strained by irradiating them with the ultrasound simultaneously generated from two point-focusing transducers by applying the sum of two signals with slightly different frequencies of approximately 1 MHz. The surface of a phantom was excited in the frequency range of 20–2,000 Hz, and its displacement was measured. The frequency dependence of the acceleration provided by the acoustic radiation force was also measured. From these results, we determined the frequency characteristics of the transfer function from the stress to the strain and estimated the ratio of the elastic modulus to the viscosity modulus (K/η) by fitting the data to the Maxwell model. Moreover, the elastic modulus K was separately estimated from the measured sound velocity and density of the phantom, and the viscosity modulus η was evaluated by substituting the estimated elastic modulus into the obtained K/η ratio.

Stress Modulus of Cancer Cells

NASA Astrophysics Data System (ADS)

Bonin, Keith; Guthold, Martin; Guo, Xinyi; Sigley, Justin

2012-02-01

Our main goal is to study the different physical and mechanical properties of cells as they advance through different stages of neoplastic transformation from normal to the metastatic state. Since recent reports indicate there is significant ambiguity about how these properties change for different cancer cells, we plan to measure these properties for a single line of cells, and to determine whether the changes vary for different cellular components: i.e. whether the change in physical properties is due to a change in the cytoskeleton, the cell membrane, the cytoplasm, or a combination of these elements. Here we expect to present data on the stress modulus of cancer cells at different stages: normal, mortal cancerous, immortal cancerous, and tumorigenic. The cells are Weinberg cell line Human Mammary Epithelial (HME) cells. Atomic force microscope (AFM) probes with different diameters are used to push on the cell membrane to measure the local, regional and global cell stress modulus. Preliminary results on normal HME cells suggests a stress modulus of 1.5 ± 0.8 kPa when pushing with 7 μm spherical probes. We anticipate reporting an improved value for the modulus as well as results for some of the Weinberg cancer cells.

Organizational resilience and enrollment trends of independent, for-profit higher education institutions.

PubMed

Frisbie, Kathryn; Converso, Judith

2016-05-24

From 2010 to 2012, the for-profit sector of higher education in the United States (otherwise known as career colleges) existed in a turbulent environment, characterized by regulatory, media, and public scrutiny. While virtually all career colleges experienced enrollment declines during this period, by 2012 some colleges were starting to see this trend stabilize or reverse, whereas others did not. The purpose of this study was to determine if the differences in career colleges' enrollment trends could be attributed to organizational resilience. A quantitative correlation study using a multiple regression analysis was conducted to determine the nature of the relationship between organizational resilience and the enrollment fluctuations of 59 career colleges located throughout the United States. The correlation between organizational resilience levels and enrollment fluctuations was fair to moderate and significant, r = 0.40, p < 0.05. A multiple-regression analysis revealed that the model significantly explained the impact of the six organizational resilience factors on enrollment fluctuations, F = 4.15, p < 0.01. The R2 for the model was 0.32, and the adjusted R2 was 0.25. In terms of individual organizational resilience factors, two tested either significantly or moderately significantly: avoidance-skepticism and critical understanding or sensemaking. Recommendations for college leaders include monitoring the level of avoidance to ensure a healthy balance of skepticism regarding new situations and incorporating strategies to help organizational members increase their levels of critical understanding or sensemaking.

Physiological Trade-Offs Along a Fast-Slow Lifestyle Continuum in Fishes: What Do They Tell Us about Resistance and Resilience to Hypoxia?

PubMed Central

Stoffels, Rick J.

2015-01-01

It has recently been suggested that general rules of change in ecological communities might be found through the development of functional relationships between species traits and performance. The physiological, behavioural and life-history traits of fishes are often organised along a fast-slow lifestyle continuum (FSLC). With respect to resistance (capacity for population to resist change) and resilience (capacity for population to recover from change) to environmental hypoxia, the literature suggests that traits enhancing resilience may come at the expense of traits promoting resistance to hypoxia; a trade-off may exist. Here I test whether three fishes occupying different positions along the FSLC trade-off resistance and resilience to environmental hypoxia. Static respirometry experiments were used to determine resistance, as measured by critical oxygen tension (Pcrit), and capacity for (RC) and magnitude of metabolic reduction (RM). Swimming respirometry experiments were used to determine aspects of resilience: critical (U crit) and optimal swimming speed (U opt), and optimal cost of transport (COTopt). Results pertaining to metabolic reduction suggest a resistance gradient across species described by the inequality Melanotaenia fluviatilis (fast lifestyle) < Hypseleotris sp. (intermediate lifestyle) < Mogurnda adspersa (slow lifestyle). The Ucrit and COTopt data suggest a resilience gradient described by the reverse inequality, and so the experiments generally indicate that three fishes occupying different positions on the FSLC trade-off resistance and resilience to hypoxia. However, the scope of inferences that can be drawn from an individual study is narrow, and so steps towards general, trait-based rules of fish community change along environmental gradients are discussed. PMID:26070078

Students' Perceptions of School Climate as Determinants of Wellbeing, Resilience and Identity

ERIC Educational Resources Information Center

Aldridge, Jill M.; Fraser, Barry J.; Fozdar, Farida; Ala'i, Kate; Earnest, Jaya; Afari, Ernest

2016-01-01

This study examined the relations between school climate variables and students' feeling of wellbeing, life satisfaction, ethnic identity, moral identity and resilience. Furthermore, the study also examined the interrelationships between these five outcome variables. Six aspects of the school climate were measured: teacher support, peer…

Steeling and Resilience in Art Education

ERIC Educational Resources Information Center

Heise, Donalyn

2014-01-01

Steel is an incredibly strong alloy of iron and carbon. Due to its incredible strength and durability, this resilient material is commonly used for constructing buildings. The transitive verb "steeling" is defined in Miriam-Webster dictionary as "to fill with resolution or determination, as in, she 'steeled herself to face the…

"He would never let me just give up": Communicatively Constructing Dyadic Resilience in the Experience of Breast Cancer.

PubMed

Lillie, Helen M; Venetis, Maria K; Chernichky-Karcher, Skye M

2017-09-27

A breast cancer diagnosis is a significant stressor that impacts both survivors' and their partners' psychological adjustment and well-being. Communication patterns and strategies utilized by survivors and partners are the key determinants of how some couples adjust to a cancer diagnosis. This study employs the Communicative theory of resilience (CTR)(Buzzanell, 2010) to examine the dyadic communicative processes couples enact that contribute to their resilience. Researchers conducted semi-structured interviews with 27 breast cancer survivors concerning communication with their partners. All interviews were transcribed and independently coded using thematic analysis. Findings support and extend the presence of the five communicative processes of resilience outlined by Buzzanell (2010), demonstrating how these processes interact with one another. Results also suggest that couples' communication both promotes and interferes with resilience. Practical and theoretical implications are discussed.

Efficient and resilient governance of social-ecological systems.

PubMed

Erickson, Adam

2015-09-01

New institutions are critically needed to improve the resilience of social-ecological systems globally. Watershed management offers an important model due to its ability to govern mixed-ownership landscapes through common property regimes, translating national goals into local action. Here, I assess the efficacy of state watershed management institutions in the Pacific Northwest, based on their ability to support local watershed groups. I use document analysis to describe and compare state institutions in Washington, Oregon, Idaho, and California. Results indicate that state institutional efficiency and resilience are the key factors determining watershed group activity and stability. The primary drivers of institutional efficiency and resilience were institutional unification, robust funding portfolios, low agency conflict, and strong support for economic multiplier effects, creative partnerships, and scholarly research. My findings elucidate the critical role of institutional efficiency and resilience in governing dynamic and complex social-ecological systems, enabling the flexibility to address emergent transformations.

Effectiveness of Resilience Training on Ego-control and Hardiness of Illicit Drug Users

PubMed Central

Roustaei, Amin; Bakhshipoor, Babollah; Doostian, Younes; Goodiny, Ali Akbar; Koohikar, Mansoureh; Massah, Omid

2017-01-01

Background The aim of this research was to determine the effectiveness of resilience training upon ego-control and hardiness of the addicted persons. Methods This was a semi-experimental study with pretest and posttest control groups which was conducted in Sari, Iran, during 2014-2015. Thirty persons were selected among 240 illicit drug users who underwent screening. Resilience training was performed in ten sessions for the experimental group. The Kobasa hardiness questionnaire and self-restraint scale (SRS) were used for data collection and multivariate covariance test was performed for data analysis. Findings According to the data, ego-control and hardiness of participants were improved significantly by resilience training (P < 0.001). Conclusion Resilience training is effective upon the rate of ego-control and self-restraint and hardiness. This method can be used in addiction treatment clinics and residential centers. PMID:29026500

Resilience among abused and neglected children grown up.

PubMed

McGloin, J M; Widom, C S

2001-01-01

Although an extensive literature has accumulated documenting the maladaptive outcomes associated with childhood victimization, a limited body of knowledge addresses resilience. This paper sought to operationalize the construct of resilience across a number of domains of functioning and time periods and to determine the extent to which abused and neglected children grown up demonstrate resilience. Substantiated cases of child abuse and neglect from 1967 to 1971 were matched on gender, age, race, and approximate family social class with nonabused and nonneglected children and followed prospectively into young adulthood. Between 1989 and 1995. 1,196 participants (676 abused and neglected and 520 controls) were administered a 2-hr in-person interview, including a psychiatric assessment. Resilience requires meeting the criteria for success across six of eight domains of functioning: employment, homelessness, education, social activity, psychiatric disorder, substance abuse, and two domains assessing criminal behavior (official arrest and self-reports of violence). Results indicate that 22% of abused and neglected individuals meet the criteria for resilience. More females met the criteria for resilience and females were successful across a greater number of domains than males. We speculate on the meaning of these findings and discuss implications for the child maltreatment field. Limitations of the study are also acknowledged.

Exploring the Relationship Between Resilience and Ostomy Adjustment in Adults With a Permanent Ostomy.

PubMed

Scardillo, Jody; Dunn, Karen S; Piscotty, Ronald

2016-01-01

The aims of this study were to describe the relationship between resilience and ostomy adjustment in adults with permanent stomas and to determine if participants who report higher levels of resilience also report higher levels of adjustment to a permanent ostomy. Descriptive, correlational research design utilizing the Roy Adaptation Model as the theoretical framework was used. Persons with permanent stomas were recruited from ostomy support groups on the East Coast of the United States. The study sample included 48 respondents. Their mean age was 66 ± 12.7 years (mean ± SD); the majority (60.4%) were women, had an ileostomy (62.5%), and had a history of inflammatory bowel disease (62.5%). Respondents completed a questionnaire that queried demographic and pertinent clinical data, along with 2 previously validated instruments, the Resilience Scale and Ostomy Adjustment Inventory-23. The relationships between levels of resilience, levels of adjustment to an ostomy, and demographic characteristics were examined. Participants with higher levels of ostomy adjustment had higher levels of resilience than respondents who reported lower levels of ostomy adjustment (r = 0.65, P ≤ .01). Findings from this study suggest that higher levels of resilience facilitate adjustment to a permanent ostomy.

Simultaneous determination of the residual stress, elastic modulus, density and thickness of ultrathin film utilizing vibrating doubly clamped micro-/nanobeams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stachiv, Ivo, E-mail: stachiv@fzu.cz; Institute of Physics, Czech Academy of Sciences, Prague; Kuo, Chih-Yun

2016-04-15

Measurement of ultrathin film thickness and its basic properties can be highly challenging and time consuming due to necessity of using several very sophisticated devices. Here, we report an easy accessible resonant based method capable to simultaneously determinate the residual stress, elastic modulus, density and thickness of ultrathin film coated on doubly clamped micro-/nanobeam. We show that a general dependency of the resonant frequencies on the axial load is also valid for in-plane vibrations, and the one depends only on the considered vibrational mode. As a result, we found that the film elastic modulus, density and thickness can be evaluatedmore » from two measured in-plane and out-plane fundamental resonant frequencies of micro-/nanobeam with and without film under different prestress forces. Whereas, the residual stress can be determined from two out-plane (in-plane) measured consecutive resonant frequencies of beam with film under different prestress forces without necessity of knowing film and substrate properties and dimensions. Moreover, we also reveal that the common uncertainties in force (and thickness) determination have a negligible (and minor) impact on the determined film properties. The application potential of the present method is illustrated on the beam made of silicon and SiO{sub 2} with deposited 20 nm thick AlN and 40 nm thick Au thin films, respectively.« less

Developing a shared understanding of the Upper Mississippi River: the foundation of an ecological resilience assessment

USGS Publications Warehouse

Bouska, Kristen; Houser, Jeff N.; De Jager, Nathan R.; Hendrickson, Jon S.

2018-01-01

The Upper Mississippi River System (UMRS) is a large and complex floodplain river ecosystem that spans the jurisdictions of multiple state and federal agencies. In support of ongoing ecosystem restoration and management by this broad partnership, we are undertaking a resilience assessment of the UMRS. We describe the UMRS in the context of an ecological resilience assessment. Our description articulates the temporal and spatial extent of our assessment of the UMRS, the relevant historical context, the valued services provided by the system, and the fundamental controlling variables that determine its structure and function. An important objective of developing the system description was to determine the simplest, adequate conceptual understanding of the UMRS. We conceptualize a simplified UMRS as three interconnected subsystems: lotic channels, lentic off-channel areas, and floodplains. By identifying controlling variables within each subsystem, we have developed a shared understanding of the basic structure and function of the UMRS, which will serve as the basis for ongoing quantitative evaluations of factors that likely contribute to the resilience of the UMRS. As we undertake the subsequent elements of a resilience assessment, we anticipate our improved understanding of interactions, feedbacks, and critical thresholds will assist natural resource managers to better recognize the system’s ability to adapt to existing and new stresses.

Orientations of dendritic growth during solidification

NASA Astrophysics Data System (ADS)

Lee, Dong Nyung

2017-03-01

Dendrites are crystalline forms which grow far from the limit of stability of the plane front and adopt an orientation which is as close as possible to the heat flux direction. Dendritic growth orientations for cubic metals, bct Sn, and hcp Zn, can be controlled by thermal conductivity, Young's modulus, and surface energy. The control factors have been elaborated. Since the dendrite is a single crystal, its properties such as thermal conductivity that influences the heat flux direction, the minimum Young's modulus direction that influences the strain energy minimization, and the minimum surface energy plane that influences the crystal/liquid interface energy minimization have been proved to control the dendritic growth direction. The dendritic growth directions of cubic metals are determined by the minimum Young's modulus direction and/or axis direction of symmetry of the minimum crystal surface energy plane. The dendritic growth direction of bct Sn is determined by its maximum thermal conductivity direction and the minimum surface energy plane normal direction. The primary dendritic growth direction of hcp Zn is determined by its maximum thermal conductivity direction and the minimum surface energy plane normal direction and the secondary dendrite arm direction of hcp Zn is normal to the primary dendritic growth direction.

Insufficiency of the Young’s modulus for illustrating the mechanical behavior of GaN nanowires

NASA Astrophysics Data System (ADS)

Zamani Kouhpanji, Mohammad Reza; Behzadirad, Mahmoud; Feezell, Daniel; Busani, Tito

2018-05-01

We use a non-classical modified couple stress theory including the acceleration gradients (MCST-AG), to precisely demonstrate the size dependency of the mechanical properties of gallium nitride (GaN) nanowires (NWs). The fundamental elastic constants, Young’s modulus and length scales of the GaN NWs were estimated both experimentally, using a novel experimental technique applied to atomic force microscopy, and theoretically, using atomic simulations. The Young’s modulus, static and the dynamic length scales, calculated with the MCST-AG, were found to be 323 GPa, 13 and 14.5 nm, respectively, for GaN NWs from a few nanometers radii to bulk radii. Analyzing the experimental data using the classical continuum theory shows an improvement in the experimental results by introducing smaller error. Using the length scales determined in MCST-AG, we explain the inconsistency of the Young’s moduli reported in recent literature, and we prove the insufficiency of the Young’s modulus for predicting the mechanical behavior of GaN NWs.

Determination of elastic modulus and residual stress of plasma-sprayed tungsten coating on steel substrate

NASA Astrophysics Data System (ADS)

You, J. H.; Höschen, T.; Lindig, S.

2006-01-01

Plasma-sprayed tungsten, which is a candidate material for the first wall armour, shows a porous, heterogeneous microstructure. Due to its characteristic morphology, the properties are significantly different from those of its dense bulk material. Measurements of the elastic modulus of this coating have not been reported in the literature. In this work Young's modulus of highly porous plasma-sprayed tungsten coatings deposited on steel (F82H) substrates was measured. For the fabrication of the coating system the vacuum plasma-spray process was applied. Measurements were performed by means of three-point and four-point bending tests. The obtained modulus values ranged from 53 to 57 GPa. These values could be confirmed by the test result of a detached coating strip, which was 54 GPa. The applied methods produced consistent results regardless of testing configurations and specimen sizes. The errors were less than 1%. Residual stress of the coating was also estimated.

Compressive Strength and Modulus of Elasticity of Concrete with Cubed Waste Tire Rubbers as Coarse Aggregates

NASA Astrophysics Data System (ADS)

Haryanto, Y.; Hermanto, N. I. S.; Pamudji, G.; Wardana, K. P.

2017-11-01

One feasible solution to overcome the issue of tire disposal waste is the use of waste tire rubber to replace aggregate in concrete. We have conducted an experimental investigation on the effect of rubber tire waste aggregate in cuboid form on the compressive strength and modulus of elasticity of concrete. The test was performed on 72 cylindrical specimens with the height of 300 mm and diameter of 150 mm. We found that the workability of concrete with waste tire rubber aggregate has increased. The concrete density with waste tire rubber aggregate was decreased, and so was the compressive strength. The decrease of compressive strength is up to 64.34%. If the content of waste tire rubber aggregate is more than 40%, then the resulting concrete cannot be categorized as structural concrete. The modulus of elasticity decreased to 59.77%. The theoretical equation developed to determine the modulus of elasticity of concrete with rubber tire waste aggregate has an accuracy of 84.27%.

Insufficiency of the Young's modulus for illustrating the mechanical behavior of GaN nanowires.

PubMed

Kouhpanji, Mohammad Reza Zamani; Behzadirad, Mahmoud; Feezell, Daniel; Busani, Tito

2018-05-18

We use a non-classical modified couple stress theory including the acceleration gradients (MCST-AG), to precisely demonstrate the size dependency of the mechanical properties of gallium nitride (GaN) nanowires (NWs). The fundamental elastic constants, Young's modulus and length scales of the GaN NWs were estimated both experimentally, using a novel experimental technique applied to atomic force microscopy, and theoretically, using atomic simulations. The Young's modulus, static and the dynamic length scales, calculated with the MCST-AG, were found to be 323 GPa, 13 and 14.5 nm, respectively, for GaN NWs from a few nanometers radii to bulk radii. Analyzing the experimental data using the classical continuum theory shows an improvement in the experimental results by introducing smaller error. Using the length scales determined in MCST-AG, we explain the inconsistency of the Young's moduli reported in recent literature, and we prove the insufficiency of the Young's modulus for predicting the mechanical behavior of GaN NWs.

Expert assessment of the resilience of drinking water and sanitation systems to climate-related hazards.

PubMed

Luh, Jeanne; Royster, Sarah; Sebastian, Daniel; Ojomo, Edema; Bartram, Jamie

2017-08-15

We conducted an expert assessment to obtain expert opinions on the relative global resilience of ten drinking water and five sanitation technologies to the following six climate-related hazards: drought, decreased inter-annual precipitation, flood, superstorm flood, wind damage, and saline intrusion. Resilience scores ranged from 1.7 to 9.9 out of a maximum resilience of 10, with high scores corresponding to high resilience. We find that for some climate-related hazards, such as drought, technologies demonstrated a large range in resilience, indicating that the choice of water and sanitation technologies is important for areas prone to drought. On the other hand, the range of resilience scores for superstorm flooding was much smaller, particularly for sanitation technologies, suggesting that the choice of technology is less of a determinant of functionality for superstorm flooding as compared to other climate-related hazards. For drinking water technologies, only treated piped utility-managed systems that use surface water had resilience scores >6.0 for all hazards, while protected dug wells were found to be one of the least resilient technologies, consistently scoring <5.0 for all hazards except wind damage. In general, sanitation technologies were found to have low to medium resilience, suggesting that sanitation systems need to be adapted to ensure functionality during and after climate-related hazards. The results of the study can be used to help communities decide which technologies are best suited for the climate-related challenges they face and help in future adaptation planning. Copyright © 2017 Elsevier B.V. All rights reserved.

Resilience, self-esteem and self-compassion in adults with spina bifida.

PubMed

Hayter, M R; Dorstyn, D S

2014-02-01

Cross-sectional survey. To examine factors that may enhance and promote resilience in adults with spina bifida. Community-based disability organisations within Australia. Ninety-seven adults with a diagnosis of spina bifida (SB) completed a survey comprising of demographic questions in addition to standardised self-report measures of physical functioning (Craig Handicap Assessment and Reporting Technique), resilience (Connor-Davidson Resilience Scale, 10 item), self-esteem (Rosenberg Self-esteem Scale), self-compassion (Self-compassion Scale) and psychological distress (Depression Anxiety Stress Scales, 21 item). The majority (66%) of respondents reported moderate to high resilience. Physical disability impacted on coping, with greater CD-RISC 10 scores reported by individuals who were functionally independent in addition to those who experienced less medical co-morbidities. Significant correlations between resilience and psychological traits (self-esteem r=0.36, P<0.01; self-compassion r=0.40, P<0.01) were also noted. However, the combined contribution of these variables only accounted for 23% of the total variance in resilience scores (R(2)=0.227, F(5,94)=5.23, P<0.01). These findings extend current understanding of the concept of resilience in adults with a congenital physical disability. The suggestion is that resilience involves a complex interplay between physical determinants of health and psychological characteristics, such as self-esteem and self-compassion. It follows that cognitive behavioural strategies with a focus on self-management may, in part, contribute to the process of resilience in this group. Further large-scale and longitudinal research will help to confirm these findings.

Strategies for enhancing medical student resilience: student and faculty member perspectives

PubMed Central

Kamei, Robert; Vidyarthi, Arpana

2018-01-01

Objectives To improve programs aimed to enhance medical student resiliency, we examined both medical student and faculty advisor perspectives on resiliency-building in an Asian medical school. Methods In two separate focus groups, a convenience sample of 8 MD-PhD students and 8 faculty advisors were asked to identify strategies for enhancing resilience. Using thematic analysis, two researchers independently examined discussion transcripts and field notes and determined themes through a consensus process. They then compared the themes to discern similarities and differences between these groups. Results Themes from the student suggestions for increasing resilience included “Perspective changes with time and experience”, “Defining effective advisors,” and “Individual paths to resiliency”. Faculty-identified themes were “Structured activities to change student perspectives,” “Structured teaching of coping strategies”, and “Institution-wide social support”. Students described themselves as individuals building their own resilience path and preferred advisors who were not also evaluators. Faculty, however, suggested systematic, structural ways to increase resilience. Conclusions Students and advisors identified some common, and many distinct strategies for enhancing medical student resilience. Student/advisor discrepancies may exemplify a cultural shift in Singapore’s medical education climate, where students value increased individualism and autonomy in their education. As medical schools create interventions to enhance resilience and combat potential student burnout, they should consider individually-tailored as well as system-wide programs to best meet the needs of their students and faculty. PMID:29334480

Alternate reading strategies and variable asymmetry of the planum temporale in adult resilient readers.

PubMed

Welcome, Suzanne E; Leonard, Christiana M; Chiarello, Christine

2010-05-01

Resilient readers are characterized by impaired phonological processing despite skilled text comprehension. We investigated orthographic and semantic processing in resilient readers to examine mechanisms of compensation for poor phonological decoding. Performance on phonological (phoneme deletion, pseudoword reading), orthographic (orthographic choice, orthographic analogy), and semantic (semantic priming, homograph resolution) tasks was compared between resilient, poor and proficient readers. Asymmetry of the planum temporale was investigated in order to determine whether atypical readers showed unusual morphology in this language-relevant region. Resilient readers showed deficits on phonological tasks similar to those shown by poor readers. We obtained no evidence that resilient readers compensate via superior orthographic processing, as they showed neither exceptional orthographic skill nor increased reliance on orthography to guide pronunciation. Resilient readers benefited more than poor or proficient readers from semantic relationships between words and experienced greater difficulty when such relationships were not present. We suggest, therefore, that resilient readers compensate for poor phonological decoding via greater reliance on word meaning relationships. The reading groups did not differ in mean asymmetry of the planum temporale. However, resilient readers showed greater variability in planar asymmetry than proficient readers. Poor readers also showed a trend towards greater variability in planar asymmetry, with more poor readers than proficient readers showing extreme asymmetry. Such increased variability suggests that university students with less reading skill display less well regulated brain anatomy than proficient readers. Copyright 2010 Elsevier Inc. All rights reserved.

Investigation of composite materials property requirements for sonic fatigue research

NASA Technical Reports Server (NTRS)

Patrick, H. V. L.

1985-01-01

Experimental techniques for determining the extensional and bending stiffness characteristics for symmetric laminates are presented. Vibrational test techniques for determining the dynamic modulus and material damping are also discussed. Partial extensional stiffness results intially indicate that the laminate theory used for predicting stiffness is accurate. It is clearly shown that the laminate theory can only be as accurate as the physical characteristics describing the lamina, which may vary significantly. It is recommended that all of the stiffness characteristics in both extension and bending be experimentally determined to fully verify the laminate theory. Dynamic modulus should be experimentally evaluated to determine if static data adequately predicts dynamic behavior. Material damping should also be ascertained because laminate damping is an order of magnitude greater than found in common metals and can significantly effect the displacement response of composite panels.

Aging and the HPA axis: Stress and resilience in older adults

PubMed Central

Gaffey, Allison E.; Bergeman, C.S.; Clark, Lee Anna; Wirth, Michelle M.

2017-01-01

Hypothalamic-pituitary-adrenal (HPA) axis function may change over the course of aging, and altered diurnal or stress-induced secretion of the hormone cortisol could predispose older adults to negative health outcomes. We propose that psychological resilience may interact with diurnal cortisol to affect health outcomes later in life. Emotion regulation and social support are two constructs that contribute to resilience and exhibit age-specific patterns in older adults. Determining how the use of resilience resources interacts with age-related diurnal cortisol will improve our understanding of the pathways between stress, resilience, and well-being. In this review, we assess published studies evaluating diurnal cortisol in older adults to better understand differences in their HPA axis functioning. Evidence thus far suggests that diurnal cortisol may increase with age, although cross-sectional studies limit the conclusions that can be drawn. We also review extant evidence connecting age-specific signatures of emotion regulation and social support with diurnal cortisol. Conclusions are used to propose a preliminary model demonstrating how resilience resources may modulate the effects of cortisol on health in aging. PMID:27377692

Psychometric properties of Connor-Davidson Resilience Scale in a Spanish sample of entrepreneurs.

PubMed

Manzano-García, Guadalupe; Ayala Calvo, Juan Carlos

2013-01-01

The literature regarding entrepreneurship suggests that the resilience of entrepreneurs may help to explain entrepreneurial success, but there is no resilience measure widely accepted by researchers. This study analyzes the psychometric properties of the Connor and Davidson Resilience Scale (CD-RISC) in a sample of Spanish entrepreneurs. A telephone survey research method was used. The participants were entrepreneurs operating in the business services sector. Interviewers telephoned a total of 900 entrepreneurs of whom 783 produced usable questionnaires. The CD-RISC was used as data collection instrument. We used principal component analysis factor and confirmatory factor analysis to determine the factor structure of the CD-RISC. Confirmatory factor analysis failed to verify the original five-factor structure of the CD-RISC, whereas principal component analysis factor yielded a 3-factor structure of resilience (hardiness, resourcefulness and optimism). In this research, 47.48% of the total variance was accounted for by three factors, and the obtained factor structure was verified through confirmatory factor analysis. The CD-RISC has been shown to be a reliable and valid tool for measuring entrepreneurs' resilience.

Attachment Style and Resiliency in Patients with Obsessive-Compulsive Personality Disorder

PubMed Central

Zakiei, Ali; Farnia, Vahid; Khkian, Zinab; Shakeri, Jalal; Golshani, Sanobar

2017-01-01

Background The goal of the present study was to determine the relationships between attachment styles and resiliency in obsessive-compulsive personality disorder. Methods A random sample of 260 subjects was obtained from the population of undergraduate students of the Nour Branch of Islamic Azad University, which is located in Mazandaran, and these subjects were enrolled in this descriptive and correlational study. The collected data included the subjects' responses to an adult attachment style questionnaire, resilience scale, and obsessive-compulsive personality disorder questionnaire. The data were analyzed with Pearson correlation coefficient indices and multiple regressions. Results The results of the data analysis showed a positive correlation (relationship) between ambivalent/avoidant attachment styles and obsessive-compulsive personality disorder and a negative correlation between resilience and obsessive-compulsive personality disorder. Furthermore, these results demonstrated that attachment style and resiliency can predict obsessive-compulsive personality disorder. In addition, no significant relationships were found between the demographic variables (convertibles) and obsessive-compulsive personality disorder. Conclusion These results suggested that attachment style and resiliency contribute to the development of obsessive-compulsive personality disorder. PMID:28197331

Attachment Style and Resiliency in Patients with Obsessive-Compulsive Personality Disorder.

PubMed

Zakiei, Ali; Alikhani, Mostafa; Farnia, Vahid; Khkian, Zinab; Shakeri, Jalal; Golshani, Sanobar

2017-01-01

The goal of the present study was to determine the relationships between attachment styles and resiliency in obsessive-compulsive personality disorder. A random sample of 260 subjects was obtained from the population of undergraduate students of the Nour Branch of Islamic Azad University, which is located in Mazandaran, and these subjects were enrolled in this descriptive and correlational study. The collected data included the subjects' responses to an adult attachment style questionnaire, resilience scale, and obsessive-compulsive personality disorder questionnaire. The data were analyzed with Pearson correlation coefficient indices and multiple regressions. The results of the data analysis showed a positive correlation (relationship) between ambivalent/avoidant attachment styles and obsessive-compulsive personality disorder and a negative correlation between resilience and obsessive-compulsive personality disorder. Furthermore, these results demonstrated that attachment style and resiliency can predict obsessive-compulsive personality disorder. In addition, no significant relationships were found between the demographic variables (convertibles) and obsessive-compulsive personality disorder. These results suggested that attachment style and resiliency contribute to the development of obsessive-compulsive personality disorder.

Endothelial, cardiac muscle and skeletal muscle exhibit different viscous and elastic properties as determined by atomic force microscopy

NASA Technical Reports Server (NTRS)

Mathur, A. B.; Collinsworth, A. M.; Reichert, W. M.; Kraus, W. E.; Truskey, G. A.

2001-01-01

This study evaluated the hypothesis that, due to functional and structural differences, the apparent elastic modulus and viscous behavior of cardiac and skeletal muscle and vascular endothelium would differ. To accurately determine the elastic modulus, the contribution of probe velocity, indentation depth, and the assumed shape of the probe were examined. Hysteresis was observed at high indentation velocities arising from viscous effects. Irreversible deformation was not observed for endothelial cells and hysteresis was negligible below 1 microm/s. For skeletal muscle and cardiac muscle cells, hysteresis was negligible below 0.25 microm/s. Viscous dissipation for endothelial and cardiac muscle cells was higher than for skeletal muscle cells. The calculated elastic modulus was most sensitive to the assumed probe geometry for the first 60 nm of indentation for the three cell types. Modeling the probe as a blunt cone-spherical cap resulted in variation in elastic modulus with indentation depth that was less than that calculated by treating the probe as a conical tip. Substrate contributions were negligible since the elastic modulus reached a steady value for indentations above 60 nm and the probe never indented more than 10% of the cell thickness. Cardiac cells were the stiffest (100.3+/-10.7 kPa), the skeletal muscle cells were intermediate (24.7+/-3.5 kPa), and the endothelial cells were the softest with a range of elastic moduli (1.4+/-0.1 to 6.8+/-0.4 kPa) depending on the location of the cell surface tested. Cardiac and skeletal muscle exhibited nonlinear elastic behavior. These passive mechanical properties are generally consistent with the function of these different cell types.

Bouncing Back by Moving Forward: Transactional Models of Risk and Resiliency. Revolutionary Studies in Child Psychology.

ERIC Educational Resources Information Center

Thurber, Christopher A.

2003-01-01

Four studies in child development show that children socialize parents as much as parents socialize children. Child development is a function of biological maturation and child-environment interaction. The most important determinants of resiliency are caregiver quality and socioeconomic status. Implications for camp are discussed, the most…

Assessing the Outcomes of School-Based Partnership Resilience Intervention

ERIC Educational Resources Information Center

Mampane, Ruth; Huddle, Christelle

2017-01-01

This study reports on the outcomes of educational psychology school-based intervention. The aim was to determine whether the intervention served as an educational pathway to resilience. Through a concurrent mixed-methods research design interpreted through a pragmatic lens, academic school performance of students in a rural school was used as an…

Adherence to the Dietary Guidelines for Americans Is Associated with Psychological Resilience in Young Adults: A Cross-Sectional Study.

PubMed

Lutz, Laura J; Gaffney-Stomberg, Erin; Williams, Kelly W; McGraw, Susan M; Niro, Philip J; Karl, J Philip; Cable, Sonya J; Cropper, Thomas L; McClung, James P

2017-03-01

The 2010 Healthy Eating Index (HEI-2010), a measure of diet quality, is used to quantify adherence to the Dietary Guidelines for Americans. Better HEI scores have been associated with positive health outcomes; however, the relationship between diet quality and psychological resilience, a mental health attribute for coping with adversity, has not been assessed. The objective of the present study was to assess the relationship between diet quality and psychological resilience, and the relationship between resilience and demographics, anthropometrics, socioeconomic status, and health behavior. In this cross-sectional study, HEI-2010 scores and resilience were assessed using the Block food frequency questionnaire and the Connor-Davidson Resilience Scale. Other factors that can affect the relationship between HEI-2010 scores and resilience were assessed using surveys, and height and weight were measured to calculate body mass index. Male and female Army and Air Force recruits (n=834) enrolled in a randomized controlled trial and 656 (mean±standard deviation [SD] age=21±3.3 years) were included in this analysis. Data were collected before the initiation of military training at Fort Sill, OK (2012-2013) and Lackland Air Force Base, TX (2013-2014). Participants were split into low- and high-resilience groups based on Connor-Davidson Resilience Scale scores. Student's t test and χ 2 tests were used to determine differences between groups for continuous and categorical variables, respectively. Logistic regression was utilized to identify predictors of resilience. Better diet quality was associated with resilience; higher HEI predicted an increased likelihood (odds ratio=1.02; 95% CI 1.01 to 1.04) of a participant being in the high-resilience group after including race, ethnicity, education, smoking, age, body mass index, sex, and military branch in the full model. The data indicate that with every 10-point increase in HEI score, there was a 22% increased likelihood of being in the high-resilience group. Registered dietitian nutritionists should continue to encourage attainable changes to improve diet; study data suggest that small improvements in diet quality can be associated with better psychological resilience. Published by Elsevier Inc.

Burnout and Resilience Among Nurses Practicing in High-Intensity Settings.

PubMed

Rushton, Cynda Hylton; Batcheller, Joyce; Schroeder, Kaia; Donohue, Pamela

2015-09-01

The high level of stress experienced by nurses leads to moral distress, burnout, and a host of detrimental effects. To support creation of healthy work environments and to design a 2-phase project to enhance nurses' resilience while improving retention and reducing turnover. In phase 1, a cross-sectional survey was used to characterize the experiences of a high-stress nursing cohort. A total of 114 nurses in 6 high-intensity units completed 6 survey tools to assess the nurses' characteristics as the context for burnout and to explore factors involved in burnout, moral distress, and resilience. Statistical analysis was used to determine associations between scale measures and to identify independent variables related to burnout. Moral distress was a significant predictor of all 3 aspects of burnout, and the association between burnout and resilience was strong. Greater resilience protected nurses from emotional exhaustion and contributed to personal accomplishment. Spiritual well-being reduced emotional exhaustion and depersonalization; physical well-being was associated with personal accomplishment. Meaning in patient care and hope were independent predictors of burnout. Higher levels of resilience were associated with increased hope and reduced stress. Resilience scores were relatively flat over years of experience. These findings provide the basis for an experimental intervention in phase 2, which is designed to help participants cultivate strategies and practices for renewal, including mindfulness practices and personal resilience plans. ©2015 American Association of Critical-Care Nurses.

Resilience: A psychobiological construct for psychiatric disorders.

PubMed

Shrivastava, Amresh; Desousa, Avinash

2016-01-01

Understanding of psychopathology of mental disorder is evolving, particularly with availability of newer insight from the field of genetics, epigenetics, social, and environmental pathology. It is now becoming clear how biological factors are contributing to development of an illness in the face of a number of psychosocial factors. Resilience is a psychobiological factor which determines individual's response to adverse life events. Resilience is a human capacity to adapt swiftly and successfully to stressful/traumatic events and manage to revert to a positive state. It is fundamental for growth of positive psychology which deals with satisfaction, adaptability, contentment, and optimism in people's life. Of late, there has been a paradigm shift in the understanding of resilience in context of stress risk vulnerability dimension. It is a neurobiological construct with significant neurobehavioral and emotional features which plays important role in deconstructing mechanism of biopsychosocial model of mental disorders. Resilience is a protective factor against development of mental disorder and a risk factor for a number of clinical conditions, e.g. suicide. Available information from scientific studies points out that resilience is modifiable factor which opens up avenues for a number of newer psychosocial as well as biological therapies. Early identification of vulnerable candidates and effectiveness of resilience-based intervention may offer more clarity in possibility of prevention. Future research may be crucial for preventive psychiatry. In this study, we aim to examine whether resilience is a psychopathological construct for mental disorder.

The Araucaria project. The distance to the small Magellanic Cloud from late-type eclipsing binaries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Graczyk, Dariusz; Pietrzyński, Grzegorz; Gieren, Wolfgang

2014-01-01

We present a distance determination to the Small Magellanic Cloud (SMC) based on an analysis of four detached, long-period, late-type eclipsing binaries discovered by the Optical Gravitational Lensing Experiment (OGLE) survey. The components of the binaries show negligible intrinsic variability. A consistent set of stellar parameters was derived with low statistical and systematic uncertainty. The absolute dimensions of the stars are calculated with a precision of better than 3%. The surface brightness-infrared color relation was used to derive the distance to each binary. The four systems clump around a distance modulus of (m – M) = 18.99 with a dispersionmore » of only 0.05 mag. Combining these results with the distance published by Graczyk et al. for the eclipsing binary OGLE SMC113.3 4007, we obtain a mean distance modulus to the SMC of 18.965 ± 0.025 (stat.) ± 0.048 (syst.) mag. This corresponds to a distance of 62.1 ± 1.9 kpc, where the error includes both uncertainties. Taking into account other recent published determinations of the SMC distance we calculated the distance modulus difference between the SMC and the Large Magellanic Cloud equal to 0.458 ± 0.068 mag. Finally, we advocate μ{sub SMC} = 18.95 ± 0.07 as a new 'canonical' value of the distance modulus to this galaxy.« less

Nano and micro mechanical properties of uncross-linked and cross-linked chitosan films

PubMed Central

Aryaei, Ashkan; Jayatissa, Ahalapitiya H.; Jayasuriya, A. Champa

2016-01-01

The aim of this study is to determine the nano and micro mechanical properties for uncross-linked and cross-linked chitosan films. Specifically, we looked at nanoindentation hardness, microhardness, and elastic modulus. It is important to study the nano and microscale mechanical properties of chitosan since chitosan has been widely used for biomedical applications. Using the solvent-cast method, the chitosan films were prepared at room temperature on the cleaned glass plates. The chitosan solution was prepared by dissolving chitosan in acetic acid 1% (v/v). Tripolyphosphate (TPP) was used to create the cross-links between amine groups in chitosan and phosphate groups in TPP. In this study, atomic force microscopy was used to measure the nanoindentation hardness and surface topography of the uncross-linked and cross-linked chitosan films. Elastic modulus was then calculated from the nanoindentation results. The effective elastic modulus was determined by microhardness with some modifications to previous theories. The microhardness of the chitosan films were measured using Vicker’s hardness meter under three different loads. Our results show that the microhardness and elastic modulus for cross-linked chitosan films are higher than the uncross-linked films. However, the cross-linked chitosan films show increased brittleness when compared to uncross-linked films. By increasing the load magnitude, the microhardness increases for both uncross-linked and cross-linked chitosan films. PMID:22100082

Nondestructive evaluation of hydrogel mechanical properties using ultrasound

PubMed Central

Walker, Jason M.; Myers, Ashley M.; Schluchter, Mark D.; Goldberg, Victor M.; Caplan, Arnold I.; Berilla, Jim A.; Mansour, Joseph M.; Welter, Jean F.

2012-01-01

The feasibility of using ultrasound technology as a noninvasive, nondestructive method for evaluating the mechanical properties of engineered weight-bearing tissues was evaluated. A fixture was designed to accurately and reproducibly position the ultrasound transducer normal to the test sample surface. Agarose hydrogels were used as phantoms for cartilage to explore the feasibility of establishing correlations between ultrasound measurements and commonly used mechanical tissue assessments. The hydrogels were fabricated in 1–10% concentrations with a 2–10 mm thickness. For each concentration and thickness, six samples were created, for a total of 216 gel samples. Speed of sound was determined from the time difference between peak reflections and the known height of each sample. Modulus was computed from the speed of sound using elastic and poroelastic models. All ultrasonic measurements were made using a 15 MHz ultrasound transducer. The elastic modulus was also determined for each sample from a mechanical unconfined compression test. Analytical comparison and statistical analysis of ultrasound and mechanical testing data was carried out. A correlation between estimates of compressive modulus from ultrasonic and mechanical measurements was found, but the correlation depended on the model used to estimate the modulus from ultrasonic measurements. A stronger correlation with mechanical measurements was found using the poroelastic rather than the elastic model. Results from this preliminary testing will be used to guide further studies of native and engineered cartilage. PMID:21773854

Improvement in engineering properties of soft-soil using cement and lime additives: A case study of southern Vietnam

NASA Astrophysics Data System (ADS)

To-Anh Phan, Vu; Ngoc-Anh Pham, Kha

2018-04-01

This paper presents the experimental results of using two additives to improve natural soft soil properties in southern Vietnam (i.g., cement and cement-lime mixture). The specimens were prepared by compacting method. Firstly, the natural soil was mixed with cement or cement-lime to determine the optimum water contents of various additive contents. Then, optimum water content was used to produce samples to test some engineering properties such as unconfined compressive strength, splitting tensile strength, and Young’s modulus. The specimens were tested by various curing duration of 7, 14, and 28 days. Results indicated that using cement additive is suitable for improvement of soft soil in the local area and cement-soil stabilization can be replaced as the subbase layer of the flexible pavement according to current Vietnamese standard. In addition, a higher cement content has a greater compressive strength as well as tensile strength. Besides, the Young’ modulus has significantly increased with a long-term curing age and more cement content. No evidences of increasing in strength and modulus are found with the cement-lime-soil stabilization. Finally, the best-fit power function is established by the relationships between unconfined compressive strength and splitting tensile strength as well unconfined compressive strength and Young’s Modulus, with the coefficient of determination, R2>0.999.

Measurement of mechanical properties of metallic glass at elevated temperature using sonic resonance method

NASA Astrophysics Data System (ADS)

Kaluvan, Suresh; Zhang, Haifeng; Mridha, Sanghita; Mukherjee, Sundeep

2017-04-01

Bulk metallic glasses are fully amorphous multi-component alloys with homogeneous and isotropic structure down to the atomic scale. Some attractive attributes of bulk metallic glasses include high strength and hardness as well as excellent corrosion and wear resistance. However, there are few reports and limited understanding of their mechanical properties at elevated temperatures. We used a nondestructive sonic resonance method to measure the Young's modulus and Shear modulus of a bulk metallic glass, Zr41.2Ti13.8Cu12.5Ni10Be22.5, at elevated temperatures. The measurement system was designed using a laser displacement sensor to detect the sonic vibration produced by a speaker on the specimen in high-temperature furnace. The OMICRON Bode-100 Vector Network Analyzer was used to sweep the frequency and its output was connected to the speaker which vibrated the material in its flexural mode and torsional modes. A Polytec OFV-505 laser vibrometer sensor was used to capture the vibration of the material at various frequencies. The flexural and torsional mode frequency shift due to the temperature variation was used to determine the Young's modulus and Shear modulus. The temperature range of measurement was from 50°C to 350°C. The Young's modulus was found to reduce from 100GPa to 94GPa for the 300°C temperature span. Similarly, the Shear modulus decreased from 38.5GPa at 50°C to 36GPa at 350°C.

The development of new, low-cost perfluoroalkylether fluids with excellent low and high-temperature properties

NASA Technical Reports Server (NTRS)

Bierschenk, Thomas R.; Kawa, Hajimu; Juhlke, Timothy J.; Lagow, Richard J.

1988-01-01

A series of perfluoroalkylether (PFAE) fluids were synthesized by direct fluorination. Viscosity-temperature properties, oxidation stabilities, oxidation-corrosion properties, and lubricity were determined. The fluids were tested in the presence of common elastomers to check for compatibility. The bulk modulus of each was measured to determine if any could be used as nonflammable aircraft hydraulic fluid. It was determined that as the carbon to oxygen ratio decreases, the viscometric properties improve, the fluids may become poor lubricants, the bulk modulus increases, the surface tension increases, and the fluid density increases. The presence of difluoromethylene oxide units in the polymer does not seriously lower the oxidation and oxidation-corrosion stabilities as long as the difluoromethylene oxide units are separated by other units.

Apparatus for in-situ nondestructive measurement of Young's modulus of plate structures

NASA Technical Reports Server (NTRS)

Huang, Jerry Qixin (Inventor); Perez, Robert J. (Inventor); DeLangis, Leo M. (Inventor)

2005-01-01

A method and apparatus for determining stiffness of a plate-like structure including a monolithic or composite laminate plate entails disposing a device for generating an acoustical pulse against a surface of the plate and disposing a detecting device against the same surface spaced a known distance from the pulse-generating device, and using the pulse-generating device to emit a pulse so as to create an extensional wave in the plate. The detecting device is used to determine a time of flight of the wave over the known distance, and the wave velocity is calculated. A Young's modulus of the plate is determined by a processor based on the wave velocity. Methods and apparatus for evaluating both isotropic plates and anisotropic laminates are disclosed.

The effect of the support program on the resilience of female family caregivers of stroke patients: Randomized controlled trial.

PubMed

İnci, Fadime Hatice; Temel, Ayla Bayik

2016-11-01

The purpose of the study was to determine the effect of a support program on the resilience of female family caregivers of stroke patients. This is a randomized controlled trial. The sample consisted 70 female family caregivers (34 experimental, 36 control group). Data were collected three times (pretest-posttest, follow-up test). Data were collected using the demographical data form, the Family Index of Regenerativity and Adaptation-General. A significant difference was determined between the experimental and control group's follow-up test scores for relative and friend support, social support and family-coping coherence. A significant difference was determined between the experimental group's mean pretest, posttest and follow-up test scores in terms of family strain, relative and friend support, social support, family coping-coherence, family hardiness and family distress. These results suggest that the Support Program contributes to the improvement of the components of resilience of family caregivers of stroke patients. Copyright © 2016 Elsevier Inc. All rights reserved.

Resilience in eating disorders: A qualitative study.

PubMed

Las Hayas, Carlota; Padierna, Jesús A; Muñoz, Pedro; Aguirre, Maialen; Gómez Del Barrio, Andrés; Beato-Fernández, Luís; Calvete, Esther

2016-07-01

The objectives of the authors in this study were two-fold: (1) to explore the role of resilience in recovery from eating disorders (EDs), and (2) to develop a model of resilience in women with EDs. Semi-structured interviews with ten women were conducted in April 2011, along with two focus groups with women who had recovered from EDs (n  = 5 women each; conducted in April 2012 at the University of Deusto, Spain), one focus group with clinical experts (n = 8; conducted in April 2012 at the Foundation Against EDs of Biskay, Spain), and six narratives from primary caregivers of ED patients living in Biskay, Spain (conducted in November 2012). All data were analyzed using a grounded theory approach. All female participants acknowledged experiencing resilience in their recovery. The analysis resulted in a conceptual model of resilience composed of the following categories: deep dissatisfaction with life, turning point, acceptance, hope, determination to change, accountability for the ED, active coping, getting social support, gaining self-knowledge, getting information about EDs, increase well-being, trait resilience, initiating new projects and living in the here and now. According to the model presented, resilience preceded the experience of recovery in women with EDs in this sample and could be a useful asset for future interventions.

Structural, elastic and electronic properties of transition metal carbides ZnC, NbC and their ternary alloys ZnxNb1-xC

NASA Astrophysics Data System (ADS)

Zidi, Y.; Méçabih, S.; Abbar, B.; Amari, S.

2018-02-01

We have investigated the structural, electronic and elastic properties of transition-metal carbides ZnxNb1-xC alloys in the range of 0 ≤ x ≤ 1 using the density functional theory (DFT). The full potential linearized augmented plane wave (FP-LAPW) method within a framework of the generalized gradient approximation (GGA) and GGA + U (where U is the Hubbard correlation terms) approach is used to perform the calculations presented here. The lattice parameters, the bulk modulus, its pressure derivative and the elastic constants were determined. We have obtained Young's modulus, shear modulus, Poisson's ratio, anisotropy factor by the aid of the calculated elastic constants. We discuss the total and partial densities of states and charge densities.

Using Photo-Elicitation Methods to Understand Resilience Among Ultra-Poor Youth and Their Caregivers in Malawi.

PubMed

Barrington, Clare; Villa-Torres, Laura; Abdoulayi, Sara; Tsoka, Maxton Grant; Mvula, Peter Matthias

2017-10-01

Unconditional cash transfer programs are a form of structural intervention to address poverty, a "fundamental cause" of disease. Such programs increasingly aim to build resilience to sustain improved outcomes and provide a solid foundation for longer term transformations. As such, there is a need to understand what resilience means in specific contexts. The goal of this formative study was to explore local experiences of resilience and vulnerability among 11 youth-caregiver dyads ( n = 22) who were beneficiaries of the Malawi Social Cash Transfer Program in Balaka district. We used a photo-elicitation approach informed by the participatory, visual methodology photovoice to guide the study and conducted an iterative content analysis using thematic coding of transcripts and photos. Participants took pictures of their daily struggles and shocks and participated in audio-recorded discussions to reflect on the photos using an adapted version of the SHOWeD method. We found that participants characterized resilience as a tireless process of using all available individual, family, and community resources at all times in pursuit of survival and well-being. In the context of daily struggles, resilience was an essential part of survival. Shocks, mostly health-related, were depicted through staged images candidly highlighting individual and environmental vulnerabilities. Community support was an essential component of resilience for both daily struggles and shocks. Using photo-elicitation methods facilitated an intergenerational, community-driven reflection on the meaning of resilience and the multilevel determinants of health in a context of extreme poverty. Findings can inform the design of resilience-focused cash transfer programs to improve health equity.

Associations between neurocognitive functioning and social and occupational resilience among South African women exposed to childhood trauma.

PubMed

Denckla, C A; Consedine, N S; Spies, G; Cherner, M; Henderson, D C; Koenen, K C; Seedat, S

2017-01-01

Background : Prior research on adaptation after early trauma among black South African women typically assessed resilience in ways that lacked contextual specificity. In addition, the neurocognitive correlates of social and occupational resilience have not been investigated. Objective : The primary aim of this exploratory study was to identify domains of neurocognitive functioning associated with social and occupational resilience, defined as functioning at a level beyond what would be expected given exposure to childhood trauma. Methods : A sample of black South African women, N  = 314, completed a neuropsychological battery, a questionnaire assessing exposure to childhood trauma, and self-report measures of functional status. We generated indices of social and occupational resilience by regressing childhood trauma exposure on social and occupational functioning, saving the residuals as indices of social and occupational functioning beyond what would be expected given exposure to childhood trauma. Results : Women with lower non-verbal memory evidenced greater social and occupational resilience above and beyond the effects attributable to age, education, HIV status, and depressive and posttraumatic stress symptoms. In addition, women with greater occupational resilience exhibited lower semantic language fluency and processing speed. Conclusion : Results are somewhat consistent with prior studies implicating memory effects in impairment following trauma, though our findings suggest that reduced abilities in these domains may be associated with greater resilience. Studies that use prospective designs and objective assessment of functional status are needed to determine whether non-verbal memory, semantic fluency, and processing speed are implicated in the neural circuitry of post-traumatic exposure resilience.

Assessing Self-concept as a Mediator Between Anger and Resilience in Adolescents With Cancer in Taiwan.

PubMed

Wu, Wei-Wen; Chang, Joanne T; Tsai, Shao-Yu; Liang, Shu-Yuan

Anger is considered a common method used by patients to relieve emotional frustrations. However, this emotional response is not a common research focus for adolescents with cancer. The aim of this study was to determine whether self-concept mediated the relationship between anger and resilience for adolescent patients currently being treated for cancer. A cross-sectional study of 40 adolescents with cancer was conducted. The instruments included the Chinese Beck Self-Concept Inventory, the Chinese Beck Anger Inventory, and the Chinese Resilience Scale. Mediation analysis was also conducted. The results indicate that (1) variations in anger significantly account for 6.86% of observed variations in self-concept, (2) variations in self-concept significantly account for 52.83% of observed variations in resilience, (3) variations in anger significantly account for 10.96% of observed variations in resilience, and (4) when paths in conditions 1 and 2 were controlled, variations in anger through self-concept significantly account for 54.04% of observed variations in resilience, and variations in anger did not significantly account for observed variations in resilience. Gender and age might affect anger control. Despite worse physical functioning and an impacted appearance, participants had normative-to-positive self-concept levels, suggesting that their self-concept might not be affected by cancer. Self-concept might play a mediating role between anger and resilience, thus helping to bridge this knowledge gap. The current gap in knowledge regarding the mediating relationship necessitates the implementation of a large-scale study designed to verify the mediating role of self-concept between anger and resilience.

The utility of resilience as a conceptual framework for understanding and measuring LGBTQ health.

PubMed

Colpitts, Emily; Gahagan, Jacqueline

2016-04-06

Historically, lesbian, gay, bisexual, transgender and queer (LGBTQ) health research has focused heavily on the risks for poor health outcomes, obscuring the ways in which LGBTQ populations maintain and improve their health across the life course. In this paper we argue that informing culturally competent health policy and systems requires shifting the LGBTQ health research evidence base away from deficit-focused approaches toward strengths-based approaches to understanding and measuring LGBTQ health. We recently conducted a scoping review with the aim of exploring strengths-based approaches to LGBTQ health research. Our team found that the concept of resilience emerged as a key conceptual framework. This paper discusses a subset of our scoping review findings on the utility of resilience as a conceptual framework in understanding and measuring LGBTQ health. The findings of our scoping review suggest that the ways in which resilience is defined and measured in relation to LGBTQ populations remains contested. Given that LGBTQ populations have unique lived experiences of adversity and discrimination, and may also have unique factors that contribute to their resilience, the utility of heteronormative and cis-normative models of resilience is questionable. Our findings suggest that there is a need to consider further exploration and development of LGBTQ-specific models and measures of resilience that take into account structural, social, and individual determinants of health and incorporate an intersectional lens. While we fully acknowledge that the resilience of LGBTQ populations is central to advancing LGBTQ health, there remains much work to be done before the concept of resilience can be truly useful in measuring LGBTQ health.

Visual force sensing with flexible nanowire buckling springs

NASA Astrophysics Data System (ADS)

Dobrokhotov, Vladimir V.; Yazdanpanah, Mehdi M.; Pabba, Santosh; Safir, Abdelilah; Cohn, Robert W.

2008-01-01

A calibrated method of force sensing is demonstrated in which the buckled shape of a long flexible metallic nanowire, referred to as a 'nanoneedle', is interpreted to determine the applied force. An individual needle of 157 nm diameter by 15.6 µm length is grown on an atomic force microscope (AFM) cantilever with a desired orientation (by the method of Yazdanpanah et al 2005 J. Appl. Phys. 98 073510). Using a nanomanipulator the needle is buckled in the chamber of a scanning electron microscope (SEM) and the buckled shapes are recorded in SEM images. Force is determined as a function of deflection for an assumed elastic modulus by fitting the shapes using the generalized elastica model (De Bona and Zelenika 1997 Proc. Inst. Mech. Eng. C 211 509-17). In this calibration the elastic modulus (68.3 GPa) was determined using an auxiliary AFM measurement, with the needle in the same orientation as in the SEM. Following this calibration the needle was used as a sensor in a different orientation than the AFM coordinates to deflect a suspended PLLA polymer fiber from which the elastic modulus (2.96 GPa) was determined. The practical value of the sensing method does depend on the reliability and ruggedness of the needle. In this study the same needle remained rigidly secured to the AFM cantilever throughout the entire SEM/AFM calibration procedure and the characterization of the nanofiber.

Determining Tension-Compression Nonlinear Mechanical Properties of Articular Cartilage from Indentation Testing.

PubMed

Chen, Xingyu; Zhou, Yilu; Wang, Liyun; Santare, Michael H; Wan, Leo Q; Lu, X Lucas

2016-04-01

The indentation test is widely used to determine the in situ biomechanical properties of articular cartilage. The mechanical parameters estimated from the test depend on the constitutive model adopted to analyze the data. Similar to most connective tissues, the solid matrix of cartilage displays different mechanical properties under tension and compression, termed tension-compression nonlinearity (TCN). In this study, cartilage was modeled as a porous elastic material with either a conewise linear elastic matrix with cubic symmetry or a solid matrix reinforced by a continuous fiber distribution. Both models are commonly used to describe the TCN of cartilage. The roles of each mechanical property in determining the indentation response of cartilage were identified by finite element simulation. Under constant loading, the equilibrium deformation of cartilage is mainly dependent on the compressive modulus, while the initial transient creep behavior is largely regulated by the tensile stiffness. More importantly, altering the permeability does not change the shape of the indentation creep curves, but introduces a parallel shift along the horizontal direction on a logarithmic time scale. Based on these findings, a highly efficient curve-fitting algorithm was designed, which can uniquely determine the three major mechanical properties of cartilage (compressive modulus, tensile modulus, and permeability) from a single indentation test. The new technique was tested on adult bovine knee cartilage and compared with results from the classic biphasic linear elastic curve-fitting program.

Elastic properties and fracture strength of quasi-isotropic graphite/epoxy composites

NASA Technical Reports Server (NTRS)

Sullivan, T. L.

1977-01-01

A research program is described which was devised to determine experimentally the elastic properties in tension and bending of quasi-isotropic laminates made from high-modulus graphite fiber and epoxy. Four laminate configurations were investigated, and determinations were made of the tensile modulus, Poisson's ratio, bending stiffness, fracture strength, and fracture strain. The measured properties are compared with those predicted by laminate theory, reasons for scatter in the experimental data are discussed, and the effect of fiber misalignment on predicted elastic tensile properties is examined. The results strongly suggest that fiber misalignment in combination with variation in fiber volume content is responsible for the scatter in both elastic constants and fracture strength.

What Doesn?t Kill You Makes You Stronger: Determinants of Stress Resiliency in Rural People of Saskatchewan, Canada

ERIC Educational Resources Information Center

Gerrard, Nikki; Kulig, Judith; Nowatzki, Nadine

2004-01-01

This article discusses a research study that explored how rural people in Saskatchewan, Canada, respond to stressful events and adversity, without outside interventions. Methods: In-depth interviews were conducted with 17 individuals who were living or had lived on a farm in Saskatchewan. The participants? definitions of resiliency, their…

Adaptive Coping under Conditions of Extreme Stress: Multilevel Influences on the Determinants of Resilience in Maltreated Children

ERIC Educational Resources Information Center

Cicchetti, Dante; Rogosch, Fred A.

2009-01-01

The study of resilience in maltreated children reveals the possibility of coping processes and resources on multiple levels of analysis as children strive to adapt under conditions of severe stress. In a maltreating context, aspects of self-organization, including self-esteem, self-reliance, emotion regulation, and adaptable yet reserved…

Role of Student Engagement in the Resilience of African American Adolescents from Low-Income Rural Communities

ERIC Educational Resources Information Center

Irvin, Matthew J.

2012-01-01

The study sought to determine whether behavioral and psychological engagement in middle school served a protective or promotive role, thereby contributing to the resilience of African American youth from low-income rural communities. Teacher reports of adjustment (i.e., aggression, academic competence, popularity) in the sixth grade were gathered.…

Mechanical Properties of Uranium Silicides by Nanoindentation and Finite Elements Modeling

NASA Astrophysics Data System (ADS)

Carvajal-Nunez, U.; Elbakhshwan, M. S.; Mara, N. A.; White, J. T.; Nelson, A. T.

2018-02-01

Three methods were used to measure the mechanical properties of {U}3{Si}, {U}_3{Si}2, and USi. Quasi-static and continuous stiffness measurement nanoindentation were used to determine hardness and Young's modulus, and microindentation was used to evaluate the bulk hardness. Hardness and Young's modulus of the three U-Si compounds were both observed to increase with Si content. Finally, finite elements modelling was used to validate the nanoindentation data calculated for {U}3{Si}2 and estimate its yield strength.

Radion tunneling in modified theories of gravity

NASA Astrophysics Data System (ADS)

Paul, Tanmoy; SenGupta, Soumitra

2018-04-01

We consider a five dimensional warped spacetime where the bulk geometry is governed by higher curvature F( R) gravity. In this model, we determine the modulus potential originating from the scalar degree of freedom of higher curvature gravity. In the presence of this potential, we investigate the possibility of modulus (radion) tunneling leading to an instability in the brane configuration. Our results reveal that the parametric regions where the tunneling probability is highly suppressed, corresponds to the parametric values required to resolve the gauge hierarchy problem.

The relationship between mechanical properties and ballistic penetration depth in a viscoelastic gel.

PubMed

Mrozek, Randy A; Leighliter, Brad; Gold, Christopher S; Beringer, Ian R; Yu, Jian H; VanLandingham, Mark R; Moy, Paul; Foster, Mark H; Lenhart, Joseph L

2015-04-01

The fundamental material response of a viscoelastic material when impacted by a ballistic projectile has important implication for the defense, law enforcement, and medical communities particularly for the evaluation of protective systems. In this paper, we systematically vary the modulus and toughness of a synthetic polymer gel to determine their respective influence on the velocity-dependent penetration of a spherical projectile. The polymer gels were characterized using tensile, compression, and rheological testing taking special care to address the unique challenges associated with obtaining high fidelity mechanical data on highly conformal materials. The depth of penetration data was accurately described using the elastic Froude number for viscoelastic gels ranging in Young's modulus from ~60 to 630 kPa. The minimum velocity of penetration was determined to scale with the gel toughness divided by the gel modulus, a qualitative estimate for the zone of deformation size scale upon impact. We anticipate that this work will provide insight into the critical material factors that control ballistic penetration behavior in soft materials and aid in the design and development of new ballistic testing media. Published by Elsevier Ltd.

Resilience: A psychobiological construct for psychiatric disorders

PubMed Central

Shrivastava, Amresh; Desousa, Avinash

2016-01-01

Understanding of psychopathology of mental disorder is evolving, particularly with availability of newer insight from the field of genetics, epigenetics, social, and environmental pathology. It is now becoming clear how biological factors are contributing to development of an illness in the face of a number of psychosocial factors. Resilience is a psychobiological factor which determines individual's response to adverse life events. Resilience is a human capacity to adapt swiftly and successfully to stressful/traumatic events and manage to revert to a positive state. It is fundamental for growth of positive psychology which deals with satisfaction, adaptability, contentment, and optimism in people's life. Of late, there has been a paradigm shift in the understanding of resilience in context of stress risk vulnerability dimension. It is a neurobiological construct with significant neurobehavioral and emotional features which plays important role in deconstructing mechanism of biopsychosocial model of mental disorders. Resilience is a protective factor against development of mental disorder and a risk factor for a number of clinical conditions, e.g. suicide. Available information from scientific studies points out that resilience is modifiable factor which opens up avenues for a number of newer psychosocial as well as biological therapies. Early identification of vulnerable candidates and effectiveness of resilience-based intervention may offer more clarity in possibility of prevention. Future research may be crucial for preventive psychiatry. In this study, we aim to examine whether resilience is a psychopathological construct for mental disorder. PMID:26985103

Psychometric validation of the French version of the Connor-Davidson Resilience Scale.

PubMed

Guihard, G; Deumier, L; Alliot-Licht, B; Bouton-Kelly, L; Michaut, C; Quilliot, F

2018-02-01

Resilience defines the ability to face adversity with positive outcomes. Different scales, including the 25-item Connor-Davidson Resilience Scale (CDRISC), have been elaborated in order to evaluate resilience among various populations. The evaluation of resilience in French populations was impossible until CDRISC was translated into French. In the present work, we aim to validate a French version of CDRISC (f-CDRISC). The survey was conducted at Nantes University. Both dental and medical students were eligible. The factor structure of f-CDRISC was determined and its replicability was tested on two sub-samples by exploratory factor analysis (EFA) and parallel analysis (PA). A third student sample was used for confirmatory factorial analysis (CFA). We collected 1210 responses. Four items did not reach acceptance thresholds for reliability and were discarded from the f-CDRISC. EFA and PA of the remaining 21 items highlighted a replicable 3-factor structure that was further confirmed by CFA. Resilience factors included "tolerance to negative affects", "tenacity" and "self-confidence". All factors displayed acceptable to good internal consistency. They were characterized by positive medium to strong correlations with the overall f-CDRISC Scale. Significant positive correlations were also observed between the resilience factors. The present work constitutes the first study devoted to a French adaptation of the CDRISC questionnaire. We present evidence showing that the f-CDRISC is a reliable tool for resilience evaluation in French speaking populations. Copyright © 2017 L'Encéphale, Paris. Published by Elsevier Masson SAS. All rights reserved.

Resilience and Its Contributing Factors in Adolescents in Long-Term Residential Care Facilities Affiliated to Tehran Welfare Organization

PubMed Central

Nourian, Manijeh; Mohammadi Shahboulaghi, Farahnaz; Nourozi Tabrizi, Kian; Rassouli, Maryam; Biglarrian, Akbar

2016-01-01

ABSTRACT Background: Resilience is a quality that affects an individual’s ability to cope with tension. The present study was conducted to determine resilience and its contributing factors in high-risk adolescents living in residential care facilities affiliated to Tehran Welfare Organization in order to help develop effective preventive measures for them. Methods: The present descriptive study was conducted on 223 adolescents living in 15 different governmental residential care centers in 2014. Participants were selected through convenience sampling. The data required were collected via the Wagnild and Young Resilience Scale with content validity (S-CVI=0.92) and a reliability of α=0.77 and r=0.83 (P<0.001). The data obtained were analyzed in SPSS-20 using descriptive and inferential statistics including Chi-square test, independent t-test and ANOVA. Results: The adolescents’ mean score of resilience was 84.41±11.01. The level of resilience was moderate in 46.2% of the participants and was significantly higher in the female than in the male adolescents (P=0.006); moreover, the score obtained was lower in primary school children as compared to middle school and high school students (P<0.001). Conclusion: Directors of care facilities and residential care personnel should adopt preventive resilience-based strategies in order to optimize resilience among adolescents, particularly the male. It is important to provide a basis to prevent adolescents’ academic failure and place a stronger value on education than the past. PMID:27713901

Methodology for rheological testing of engineered biomaterials at low audio frequencies

NASA Astrophysics Data System (ADS)

Titze, Ingo R.; Klemuk, Sarah A.; Gray, Steven

2004-01-01

A commercial rheometer (Bohlin CVO120) was used to mechanically test materials that approximate vocal-fold tissues. Application is to frequencies in the low audio range (20-150 Hz). Because commercial rheometers are not specifically designed for this frequency range, a primary problem is maintaining accuracy up to (and beyond) the mechanical resonance frequency of the rotating shaft assembly. A standard viscoelastic material (NIST SRM 2490) has been used to calibrate the rheometric system for an expanded frequency range. Mathematically predicted response curves are compared to measured response curves, and an error analysis is conducted to determine the accuracy to which the elastic modulus and the shear modulus can be determined in the 20-150-Hz region. Results indicate that the inertia of the rotating assembly and the gap between the plates need to be known (or determined empirically) to a high precision when the measurement frequency exceeds the resonant frequency. In addition, a phase correction is needed to account for the magnetic inertia (inductance) of the drag cup motor. Uncorrected, the measured phase can go below the theoretical limit of -π. This can produce large errors in the viscous modulus near and above the resonance frequency. With appropriate inertia and phase corrections, +/-10% accuracy can be obtained up to twice the resonance frequency.

Can reliable values of Young's modulus be deduced from Fisher's (1971) spinning lens measurements?

PubMed

Burd, H J; Wilde, G S; Judge, S J

2006-04-01

The current textbook view of the causes of presbyopia rests very largely on a series of experiments reported by R.F. Fisher some three decades ago, and in particular on the values of lens Young's modulus inferred from the deformation caused by spinning excised lenses about their optical axis (Fisher 1971) We studied the extent to which inferred values of Young's modulus are influenced by assumptions inherent in the mathematical procedures used by Fisher to interpret the test and we investigated several alternative interpretation methods. The results suggest that modelling assumptions inherent in Fisher's original method may have led to systematic errors in the determination of the Young's modulus of the cortex and nucleus. Fisher's conclusion that the cortex is stiffer than the nucleus, particularly in middle age, may be an artefact associated with these systematic errors. Moreover, none of the models we explored are able to account for Fisher's claim that the removal of the capsule has only a modest effect on the deformations induced in the spinning lens.

Quantitative Evaluation of the Effect of Porosity on the Local Young's Modulus of Isotropic Composites by Using the Laser Optoacoustic Method

NASA Astrophysics Data System (ADS)

Podymova, N. B.; Karabutov, A. A.; Kobeleva, L. I.; Chernyshova, T. A.

2013-09-01

An impulse acoustic method with a laser source of ultrasound is proposed and realized experimentally for a quantitative evaluation of the joint effect of porosity (the volume fraction of pores) and the concentration of dispersed filler on the local Young's modulus of isotropic metal-matrix composite materials. The determination of Young's modulus is based on the laser thermooptical excitation of ultrasound and measurements of the phase speed of longitudinal and shears acoustic waves in composite specimens. Silumin-matrix composite specimens reinforced with various volume fractions of silicon carbide (SiC) microparticles of the mean size of 14 μm were investigated. It was found that, to provide an effective growth in Young's modulus by increasing the concentration of SiC, the porosity of a ready specimen should not exceed 2%. The technique developed allows one to carry out a nondestructive local testing of the acoustical and mechanical properties of composites in the actual state, which is necessary for a technological development and improvement of the fabrication process of the materials.

Modelling of single walled carbon nanotube cylindrical structures with finite element method simulations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Günay, E.

In this study, the modulus of elasticity and shear modulus values of single-walled carbon nanotubes SWCNTs were modelled by using both finite element method and the Matlab code. Initially, cylindrical armchair and zigzag single walled 3D space frames were demonstrated as carbon nanostructures. Thereafter, macro programs were written by the Matlab code producing the space truss for zigzag and armchair models. 3D space frames were introduced to the ANSYS software and then tension, compression and additionally torsion tests were performed on zigzag and armchair carbon nanotubes with BEAM4 element in obtaining the exact values of elastic and shear modulus values.more » In this study, two different boundary conditions were tested and especially used in torsion loading. The equivalent shear modulus data was found by averaging the corresponding values obtained from ten different nodal points on the nanotube path. Finally, in this study it was determined that the elastic constant values showed proportional changes by increasing the carbon nanotube diameters up to a certain level but beyond this level these values remained stable.« less

Correlation between failure and local material property in chopped carbon fiber chip-reinforced sheet molding compound composites under tensile load

DOE PAGES

Tang, Haibin; Chen, Zhangxing; Zhou, Guowei; ...

2018-02-06

To develop further understanding towards the role of a heterogeneous microstructure on tensile crack initiation and failure behavior in chopped carbon fiber chip-reinforced composites, uni-axial tensile tests are performed on coupons cut from compression molded plaque with varying directions. Our experimental results indicate that failure initiation is relevant to the strain localization, and a new criterion with the nominal modulus to predict the failure location is proposed based on the strain analysis. Furthermore, optical microscopic images show that the nominal modulus is determined by the chip orientation distribution. At the area with low nominal modulus, it is found that chipsmore » are mostly aligning along directions transverse to loading direction and/or less concentrated, while at the area with high nominal modulus, more chips are aligning to tensile direction. On the basis of failure mechanism analysis, it is concluded that transversely-oriented chips or resin-rich regions are easier for damage initiation, while longitudinally-oriented chips postpone the fracture. Good agreement is found among failure mechanism, strain localization and chip orientation distribution.« less

Correlation between failure and local material property in chopped carbon fiber chip-reinforced sheet molding compound composites under tensile load

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tang, Haibin; Chen, Zhangxing; Zhou, Guowei

To develop further understanding towards the role of a heterogeneous microstructure on tensile crack initiation and failure behavior in chopped carbon fiber chip-reinforced composites, uni-axial tensile tests are performed on coupons cut from compression molded plaque with varying directions. Our experimental results indicate that failure initiation is relevant to the strain localization, and a new criterion with the nominal modulus to predict the failure location is proposed based on the strain analysis. Furthermore, optical microscopic images show that the nominal modulus is determined by the chip orientation distribution. At the area with low nominal modulus, it is found that chipsmore » are mostly aligning along directions transverse to loading direction and/or less concentrated, while at the area with high nominal modulus, more chips are aligning to tensile direction. On the basis of failure mechanism analysis, it is concluded that transversely-oriented chips or resin-rich regions are easier for damage initiation, while longitudinally-oriented chips postpone the fracture. Good agreement is found among failure mechanism, strain localization and chip orientation distribution.« less

Resilience moderates the relationship between emotional intelligence and clinical communication ability among Chinese practice nursing students: A structural equation model analysis.

PubMed

Kong, Linghua; Liu, Yun; Li, Guopeng; Fang, Yueyan; Kang, Xiaofei; Li, Ping

2016-11-01

To examine the positive association between emotional intelligence and clinical communication ability among practice nursing students, and to determine whether resilience plays a moderating role in the relationship between emotional intelligence and clinical communication ability among Chinese practice nursing students. Three hundred and seventy-seven practice nursing students from three hospitals participated in this study. They completed questionnaires including the Emotional Intelligence Inventory (EII), Connor-Davidson Resilience Scale (CD-RISC-10), and Clinical Communication Ability Scale (CCAS). Structural equation modeling was used to analyze the relationships among emotional intelligence, resilience, and clinical communication ability. Emotional intelligence was positively associated with clinical communication ability (P<0.01). Resilience significantly affected clinical communication ability (P<0.01) and moderated the relationship between emotional intelligence and clinical communication ability (P<0.01). Emotional intelligence is positively related to clinical communication ability among Chinese practice nursing students, and resilience moderates the relationship between emotional intelligence and clinical communication ability, which may provide scientific evidence to aid in developing intervention strategies to improve clinical communication ability. Copyright © 2016 Elsevier Ltd. All rights reserved.

Rehabilitation reliability of the road pavement structure with recycled base course with foamed bitumen

NASA Astrophysics Data System (ADS)

Buczyński, P.

2018-05-01

This article presents a new approach to reliability assessment of the road structure in which the base layer will be constructed in the process of cold deep recycling with foamed bitumen. In order to properly assess the reliability of the structure with the recycled base, it is necessary to determine the distribution of stress and strain in typical pavement layer systems. The true stress and strain values were established for particular structural layers using the complex modulus (E*) determined based on the master curves. The complex modulus was determined by the direct tension-compression test on cylindrical specimens (DTC-CY) at five temperatures (-7°C, 5°C, 13°C, 25°C, 40°C) and six loading times (0.1 Hz, 0.3 Hz, 1 Hz, 3 Hz, 10 Hz, 20 Hz) in accordance with EN 12697-26 in the linear viscoelasticity (LVE) range for small strains ranging from 25 to 50 με. The master curves of the complex modulus were constructed using the Richards model for the mixtures typically incorporated in structural layers, i.e., SMA11, AC16W, AC22P and MCAS. The values of the modulus characterizing particular layers were determined with temperature distribution in the structure taken into account, when the surface temperature was 40°C. The stress distribution was established for those calculation models. The stress values were used to evaluate the fatigue life under controlled stress conditions (IT-FT). This evaluation, with the controlled stress corresponding to that in the structure, facilitated the quality assessment of the rehabilitated recycled base course. Results showed that the recycled base mixtures having the indirect tensile strength (ITSDRY) similar to the stress in the structure under analysis needed an additional fatigue life evaluation in the indirect tensile test ITT. This approach to the recycled base quality assessment will allow eliminating the damage induced by overloading.

Psychosocial factors affecting resilience in Nepalese individuals with earthquake-related spinal cord injury: a cross-sectional study.

PubMed

Bhattarai, Muna; Maneewat, Khomapak; Sae-Sia, Wipa

2018-03-02

One of many types of injuries following an earthquake is spinal cord injury (SCI) which is a life-long medically complex injury and high-cost health problem. Despite several negative consequences, some persons with SCI are resilient enough to achieve positive adjustment, greater acceptance, and better quality of life. Since resilience is influenced by several factors and can vary by context, it is beneficial to explore factors that affect the resilience of people who sustained spinal cord injury from the 2015 earthquake in Nepal. A descriptive cross-sectional study included 82 participants from the Spinal Injury Rehabilitation Center and communities in Nepal. Participants completed the Demographic and Injury-related Questionnaire, Connor-Davidson Resilience Scale, Multidimensional Scale of Perceived Social Support, Moorong Self-efficacy Scale, Intrinsic Spirituality Scale, and Patient Health Questionnaire-9. Pearson's correlation and point biserial correlation analyses were performed to examine associations between resilience and independent variables. A hierarchical regression analysis was used to identify the influence of certain factors. Findings indicated significant associations between resilience and social support (r = 0.42, p < 0.001), self-efficacy (r = 0.53, p < 0.001), depressive mood (r = - 0.50, p < 0.001) and demographic variables which included sex (r = 0.47, p < 0.001), employment (r = 0.27, p = 0.016), and current living location (r = 0.24, p = 0.029). There was a non-significant association between resilience and spirituality (r = - 0.12, p > 0.05). In hierarchical regression analysis, an overall regression model explained 46% of the variance in resilience. Self-efficacy (β = 0.28, p = 0.007) and depressive mood (β = - 0.24, p = 0.016) significantly determined resilience after controlling the effect of demographic variables. Among the demographic factors, being male significantly explained the variance in resilience (β = 0.31, p = 0.001). Multiple psychosocial and demographic factors were associated with resilience in people who sustained an earthquake-related SCI. Mental health professionals should demonstrate concern and consider such factors in allocating care in this group. Development of intervention research concerning resilience is recommended to strengthen resilience in order to improve rehabilitation outcomes and enhance reintegration of individuals with SCI into their communities.

Land-use systems and resilience of tropical rain forests in the Tehuantepec Isthmus, Mexico.

PubMed

García-Romero, Arturo; Oropeza-Orozco, Oralia; Galicia-Sarmiento, Leopoldo

2004-12-01

Land-cover types were analyzed for 1970, 1990 and 2000 as the bases for determining land-use systems and their influence on the resilience of tropical rain forests in the Tehuantepec Isthmus, Mexico. Deforestation (DR) and mean annual transformation rates were calculated from land-cover change data; thus, the classification of land-use change processes was determined according to their impact on resilience: a) Modification, including land-cover conservation and intensification, and b) Conversion, including disturbance and regeneration processes. Regeneration processes, from secondary vegetation under extensive use, cultivated vegetation under intensive use, and cultivated or induced vegetation under extensive use to mature or secondary vegetation, have high resilience capacity. In contrast, cattle-raising is characterized by rapid expansion, long-lasting change, and intense damages; thus, recent disturbance processes, which include the conversion to cattle-raising, provoke the downfall of the traditional agricultural system, and nullify the capacity of resilience of tropical rain forest. The land-use cover change processes reveal a) the existence of four land-use systems (forestry, extensive agriculture, extensive cattle-raising, and intensive uses) and b) a trend towards the replacement of agricultural and forestry systems by extensive cattle-raising, which was consolidated during 1990-2000 (DR of evergreen tropical rain forest = 4.6%). Only the forestry system, which is not subject to deforestation, but is affected by factors such as selective timber, extraction, firewood collection, grazing, or human-induced fire, is considered to have high resilience (2 years), compared to agriculture (2-10 years) or cattle-raising (nonresilient). It is concluded that the analysis of land-use systems is essential for understanding the implications of land-use cover dynamics on forest recovery and land degradation in tropical rain forests.

Viscoelastic properties of uncured resin composites: Dynamic oscillatory shear test and fractional derivative model.

PubMed

Petrovic, Ljubomir M; Zorica, Dusan M; Stojanac, Igor Lj; Krstonosic, Veljko S; Hadnadjev, Miroslav S; Janev, Marko B; Premovic, Milica T; Atanackovic, Teodor M

2015-08-01

In this study we analyze viscoelastic properties of three flowable (Wave, Wave MV, Wave HV) and one universal hybrid resin (Ice) composites, prior to setting. We developed a mathematical model containing fractional derivatives in order to describe their properties. Isothermal experimental study was conducted on a rheometer with parallel plates. In dynamic oscillatory shear test, storage and loss modulus, as well as the complex viscosity where determined. We assumed four different fractional viscoelastic models, each belonging to one particular class, derivable from distributed-order fractional constitutive equation. The restrictions following from the Second law of thermodynamics are imposed on each model. The optimal parameters corresponding to each model are obtained by minimizing the error function that takes into account storage and loss modulus, thus obtaining the best fit to the experimental data. In the frequency range considered, we obtained that for Wave HV and Wave MV there exist a critical frequency for which loss and storage modulus curves intersect, defining a boundary between two different types of behavior: one in which storage modulus is larger than loss modulus and the other in which the situation is opposite. Loss and storage modulus curves for Ice and Wave do not show this type of behavior, having either elastic, or viscous effects dominating in entire frequency range considered. The developed models may be used to predict behavior of four tested composites in different flow conditions (different deformation speed), thus helping to estimate optimal handling characteristics for specific clinical applications. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Experimental evaluation of foil-supported resilient-pad gas-lubricated thrust bearing

NASA Technical Reports Server (NTRS)

Nemeth, Z. N.

1977-01-01

A new type of resilient-pad gas thrust bearing was tested to determine the feasibility of the design. The bearing consists of carbon graphite pads mounted asymmetrically on foil beams. Two bearing configurations were tested at thrust loads from 27 to 80 newtons at speeds to 9000 rpm. The outside diameter of the bearing was 8.9 centimeters.

"Luchando y Logrando"/Struggling and Achieving: Resilience of Latina/o Math and Science Teacher Candidates at California Hispanic-Serving Institutions: A Critical Race Perspective

ERIC Educational Resources Information Center

Gonzalez, Laura

2013-01-01

Latin@ math and science students represent a resilient, determined, and encouraging group of high achievers. This qualitative study presents the narratives of 10 Latin@ science and math teacher candidates currently attending Hispanic-Serving Institutions in California. Semi structured, in-depth interviews were conducted, where participants shared…

A Multiple Case Study: The Effect of Professional Development on Teachers' Perceived Ability to Foster Resilience

ERIC Educational Resources Information Center

Klinger, Mary A.

2012-01-01

The purpose of this mixed methods study was to determine the effect of professional development on teachers' perceptions of their ability to foster resilience. Secondary questions investigated the effects of school level and socioeconomic status. An exploratory multi-site case study was designed to compare the perceptions of educators from…

Mindfulness goes to work: impact of an online workplace intervention.

PubMed

Aikens, Kimberly A; Astin, John; Pelletier, Kenneth R; Levanovich, Kristin; Baase, Catherine M; Park, Yeo Yung; Bodnar, Catherine M

2014-07-01

The objective of this study was to determine whether a mindfulness program, created for the workplace, was both practical and efficacious in decreasing employee stress while enhancing resiliency and well-being. Participants (89) recruited from The Dow Chemical Company were selected and randomly assigned to an online mindfulness intervention (n = 44) or wait-list control (n = 45). Participants completed the Perceived Stress Scale, the Five Facets of Mindfulness Questionnaire, the Connor-Davidson Resiliency Scale, and the Shirom Vigor Scale at pre- and postintervention and 6-month follow-up. The results indicated that the mindfulness intervention group had significant decreases in perceived stress as well as increased mindfulness, resiliency, and vigor. This online mindfulness intervention seems to be both practical and effective in decreasing employee stress, while improving resiliency, vigor, and work engagement, thereby enhancing overall employee well-being.

Engineering characterisation of epoxidized natural rubber-modified hot-mix asphalt

PubMed Central

Al-Mansob, Ramez A.; Ismail, Amiruddin; Yusoff, Nur Izzi Md.; Rahmat, Riza Atiq O. K.; Borhan, Muhamad Nazri; Albrka, Shaban Ismael; Azhari, Che Husna; Karim, Mohamed Rehan

2017-01-01

Road distress results in high maintenance costs. However, increased understandings of asphalt behaviour and properties coupled with technological developments have allowed paving technologists to examine the benefits of introducing additives and modifiers. As a result, polymers have become extremely popular as modifiers to improve the performance of the asphalt mix. This study investigates the performance characteristics of epoxidized natural rubber (ENR)-modified hot-mix asphalt. Tests were conducted using ENR–asphalt mixes prepared using the wet process. Mechanical testing on the ENR–asphalt mixes showed that the resilient modulus of the mixes was greatly affected by testing temperature and frequency. On the other hand, although rutting performance decreased at high temperatures because of the increased elasticity of the ENR–asphalt mixes, fatigue performance improved at intermediate temperatures as compared to the base mix. However, durability tests indicated that the ENR–asphalt mixes were slightly susceptible to the presence of moisture. In conclusion, the performance of asphalt pavement can be enhanced by incorporating ENR as a modifier to counter major road distress. PMID:28182724

Rehabilitating asphalt highways

DOE Office of Scientific and Technical Information (OSTI.GOV)

Butalia, T.S.

2007-07-01

Coal fly ash has been used on two Ohio full-depth reclamation projects in Delaware and Warren. The object of the project carried out with the Department of Civil and Environmental Engineering and Geodetic Science at Ohio State University is to demonstrate the effective use of Class fly ash in combination with lime or lime kiln dust in the full depth reclamation of asphalt pavements. The article describes the mixes used for the highway reconstruction of part of Section Line Road Delaware County and of a road in Warren County. During construction the pavement sections were instrumented with several structural andmore » environmental monitoring devices and data is being collected on a quarterly basis. Falling Weight Deflectometer (FWD) tests to measure load defection behaviour, resilient of pavement layers and soil and base structural layer coefficient are being carried out twice a year. It was shown that use of fly ash increased the elastic modulus of base layers. This article first appeared in the Feb/May 2007 issue of Asphalt Contractor. 4 photos.« less

Ni-Ti Alloys for Aerospace Bearing Applications

NASA Technical Reports Server (NTRS)

DellaCorte, Christopher

2017-01-01

Nickel-rich Ni-Ti alloys are emerging candidate materials for aerospace bearing applications. These alloys exhibit a unique combination of physical, chemical, and tribological properties that are highly relevant to challenging aerospace bearings and other mechanical components. Despite being made solely from metals, Ni-Ti alloys are classified as intermetallics with properties akin to both metals and ceramics. For instance, like metals, they are electrically conductive but they tend to be brittle like ceramics. When properly processed, they have high hardness, low elastic modulus and an extensive elastic deformation range that imparts extraordinarily high resilience and resistance to denting. New alloy compositions enable simpler thermal processing and machining and intensive microstructural analyses have helped elucidate the materials science mechanisms governing hardness. In this paper, the application of state-of-art in NiTi alloys for aerospace bearings and mechanical components is explored. In addition to reviewing future trends and remaining challenges, the unique approaches and methods of tailoring bearing design to accommodate NiTis unique properties is discussed.

Engineering characterisation of epoxidized natural rubber-modified hot-mix asphalt.

PubMed

Al-Mansob, Ramez A; Ismail, Amiruddin; Yusoff, Nur Izzi Md; Rahmat, Riza Atiq O K; Borhan, Muhamad Nazri; Albrka, Shaban Ismael; Azhari, Che Husna; Karim, Mohamed Rehan

2017-01-01

Road distress results in high maintenance costs. However, increased understandings of asphalt behaviour and properties coupled with technological developments have allowed paving technologists to examine the benefits of introducing additives and modifiers. As a result, polymers have become extremely popular as modifiers to improve the performance of the asphalt mix. This study investigates the performance characteristics of epoxidized natural rubber (ENR)-modified hot-mix asphalt. Tests were conducted using ENR-asphalt mixes prepared using the wet process. Mechanical testing on the ENR-asphalt mixes showed that the resilient modulus of the mixes was greatly affected by testing temperature and frequency. On the other hand, although rutting performance decreased at high temperatures because of the increased elasticity of the ENR-asphalt mixes, fatigue performance improved at intermediate temperatures as compared to the base mix. However, durability tests indicated that the ENR-asphalt mixes were slightly susceptible to the presence of moisture. In conclusion, the performance of asphalt pavement can be enhanced by incorporating ENR as a modifier to counter major road distress.

Value-added utilisation of recycled concrete in hot-mix asphalt.

PubMed

Wong, Yiik Diew; Sun, Darren Delai; Lai, Dickson

2007-01-01

The feasibility of partial substitution of granite aggregate in hot-mix asphalt (HMA) with waste concrete aggregate was investigated. Three hybrid HMA mixes incorporating substitutions of granite fillers/fines with 6%, 45% untreated, and 45% heat-treated concrete were evaluated by the Marshall mix design method; the optimum binder contents were found to be 5.3%, 6.5% and 7.0% of grade Pen 60/70 bitumen, respectively. All three hybrid mixes satisfied the Marshall criteria of the Singapore Land Transport Authority (LTA) W3B wearing course specification. The hybrid mix with 6% concrete fillers gave comparable resilient modulus and creep resistance as the conventional W3B mix, while hybrid mixes with higher concrete substitutions achieved better performance. X-ray diffraction (XRD) showed the distinct presence of free lime in the heat-treated concrete, while the scanning electron microscope (SEM) provided an in-depth perspective of the concrete grains in the HMA matrix. The results suggest feasible use of waste concrete as partial aggregate substitution in HMA.

Deformation Behavior of Recycled Concrete Aggregate during Cyclic and Dynamic Loading Laboratory Tests

PubMed Central

Sas, Wojciech; Głuchowski, Andrzej; Gabryś, Katarzyna; Soból, Emil; Szymański, Alojzy

2016-01-01

Recycled concrete aggregate (RCA) is a relatively new construction material, whose applications can replace natural aggregates. To do so, extensive studies on its mechanical behavior and deformation characteristics are still necessary. RCA is currently used as a subbase material in the construction of roads, which are subject to high settlements due to traffic loading. The deformation characteristics of RCA must, therefore, be established to find the possible fatigue and damage behavior for this new material. In this article, a series of triaxial cyclic loading and resonant column tests is used to characterize fatigue in RCA as a function of applied deviator stress after long-term cyclic loading. A description of the shakedown phenomenon occurring in the RCA and calculations of its resilient modulus (Mr) as a function of fatigue are also presented. Test result analysis with the stress-life method on the Wohler S-N diagram shows the RCA behavior in accordance with the Basquin law. PMID:28773905

The presence of resilience is associated with a healthier psychological profile in intensive care unit (ICU) nurses: results of a national survey.

PubMed

Mealer, Meredith; Jones, Jacqueline; Newman, Julia; McFann, Kim K; Rothbaum, Barbara; Moss, Marc

2012-03-01

ICU nurses are repeatedly exposed to work related stresses resulting in the development of psychological disorders including posttraumatic stress disorder and burnout syndrome. Resilience is a learnable multidimensional characteristic enabling one to thrive in the face of adversity. In a national survey, we sought to determine whether resilience was associated with healthier psychological profiles in intensive care unit nurses. Surveys were mailed to 3500 randomly selected ICU nurses across the United States and included: demographic questions, the Posttraumatic Diagnostic Scale, Hospital Anxiety and Depression Scale, Maslach Burnout Inventory and the Connor-Davidson Resilience Scale. Overall, 1239 of the mailed surveys were returned for a response rate of 35%, and complete data was available on a total of 744 nurses. Twenty-two percent of the intensive care unit nurses were categorized as being highly resilient. The presence of high resilience in these nurses was significantly associated with a lower prevalence of posttraumatic stress disorder, symptoms of anxiety or depression, and burnout syndrome (<0.001 for all comparisons). In independent multivariable analyses adjusting for five potential confounding variables, the presence of resilience was independently associated with a lower prevalence of posttraumatic stress disorder (p<0.001), and a lower prevalence of burnout syndrome (p<0.001). The presence of psychological resilience was independently associated with a lower prevalence of posttraumatic stress disorder and burnout syndrome in intensive care unit nurses. Future research is needed to better understand coping mechanisms employed by highly resilient nurses and how they maintain a healthier psychological profile. Copyright © 2011 Elsevier Ltd. All rights reserved.

Elderly people coping with the aftermath of war: resilience versus vulnerability.

PubMed

Kimhi, Shaul; Hantman, Shira; Goroshit, Marina; Eshel, Yohanan; Zysberg, Leehu

2012-05-01

The present study compares coping of elderly people and two younger groups 1 year after a war. Coping was determined by stress symptoms and posttraumatic recovery and two levels of resiliency. Thirty-six streets (covering most of the city streets) were sampled randomly from the map of Kiryat Shemona (a town next to the Lebanese border) about a year after the end of the Second Lebanon War. The sample constituted 870 adult residents of the town. Participants were divided into three age groups: elderly (age 65 years and older, N = 108), adults (age 46-64 years, N = 252) and young adults (age 20-45 years, N = 462). 1) Stress symptoms measured by short version of Brief Symptom Inventory; 2) Individual resilience measured by Sense of Coherence Inventory; 3) Posttraumatic Recovery Inventory (PTR); and 4) Public Resilience Scale (included a scale for community and national resilience). The results indicated 1) The elderly group reported significantly higher levels of stress symptoms and lower levels of PTR; 2) Females in the three age groups reported higher levels of stress symptoms and lower levels of PTR and individual resilience than males; 3) Individual and public resilience negatively predicted stress symptoms and positively predicted posttraumatic recovery across three age groups; and 4) Public resilience has a differential effect on stress symptoms in each of the three age groups but not on PTR. Results question the division of older people into a vulnerable or inoculated group, indicating that the participants responded concurrently in a more vulnerable and a more resilient manner. Older people were characterized by higher levels of postwar stress symptoms, as well as a higher sense of coherence.

Lack of Resilience Is Related to Stress-Related Sleep Reactivity, Hyperarousal, and Emotion Dysregulation in Insomnia Disorder.

PubMed

Palagini, Laura; Moretto, Umberto; Novi, Martina; Masci, Isabella; Caruso, Danila; Drake, Christopher L; Riemann, Dieter

2018-05-15

According to the diathesis-stress model of insomnia, insomnia may develop in vulnerable individuals in response to stress. Resilience is a psychobiological factor that determines an individual's capacity to adapt successfully to stressful events and low resilience increases vulnerability for development of mental disorders. The aim was to explore resilience in subjects with insomnia and its relationship with the factors that contribute to its development and perpetuation. The study consisted of 58 subjects with Insomnia Disorder according to the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition and 38 good sleepers. Resilience Scale for Adults (RSA), Ford Insomnia Response to Stress Test (FIRST), Pre-sleep Arousal Scale (PSAS), and Difficulties in Emotion Regulation Scale (DERS) were administered while taking into account psychiatric symptoms. Differences in means between groups were assessed using t test or Mann-Whitney U /Wilcoxon test. Linear/multivariable regression analyses and mediation analyses were performed. Subjects with insomnia (24 females, mean age 49 ± 2.1 years) had lower RSA and higher FIRST, DERS, and PSAS scores than good sleepers (22 females, mean age 47.2 ± 1.2 years). After controlling for anxiety/depressive symptoms, low resilience correlated with high stress-related sleep reactivity ( P = .004), pre-sleep cognitive hyperarousal ( P = .01) and emotion dysregulation ( P = .01). Emotion dysregulation mediated the relationship between low resilience and cognitive hyperarousal (Z = 2.06, P = .03). Subjects with insomnia showed low resilience, which was related to high stress-related sleep reactivity, emotional dysregulation, and hyperarousal. If resilience helps to minimize the extent of pathogenesis in the developmental process, an early identification of vulnerable candidates should be useful for preventing insomnia development and maintenance. A commentary on this article appears in this issue on page 709. © 2018 American Academy of Sleep Medicine.

Developing a community-based flood resilience measurement standard

NASA Astrophysics Data System (ADS)

Keating, Adriana; Szoenyi, Michael; Chaplowe, Scott; McQuistan, Colin; Campbell, Karen

2015-04-01

Given the increased attention to resilience-strengthening in international humanitarian and development work, there has been concurrent interest in its measurement and the overall accountability of "resilience strengthening" initiatives. The literature is reaching beyond the polemic of defining resilience to its measurement. Similarly, donors are increasingly expecting organizations to go beyond claiming resilience programing to measuring and showing it. However, key questions must be asked, in particular "Resilience of whom and to what?". There is no one-size-fits-all solution. The approach to measuring resilience is dependent on the audience and the purpose of the measurement exercise. Deriving a resilience measurement system needs to be based on the question it seeks to answer and needs to be specific. This session highlights key lessons from the Zurich Flood Resilience Alliance approach to develop a flood resilience measurement standard to measure and assess the impact of community based flood resilience interventions, and to inform decision-making to enhance the effectiveness of these interventions. We draw on experience in methodology development to-date, together with lessons from application in two case study sites in Latin America. Attention will be given to the use of a consistent measurement methodology for community resilience to floods over time and place; challenges to measuring a complex and dynamic phenomenon such as community resilience; methodological implications of measuring community resilience versus impact on and contribution to this goal; and using measurement and tools such as cost-benefit analysis to prioritize and inform strategic decision making for resilience interventions. The measurement tool follows the five categories of the Sustainable Livelihoods Framework and the 4Rs of complex adaptive systems - robustness, rapidity, redundancy and resourcefulness -5C-4R. A recent white paper by the Zurich Flood Resilience Alliance traces the literature on resilience in the area of disaster risk (see corresponding abstract of another session). The research gap, which was also highlighted in the 2012 National Academies of Sciences Paper (Disasters, Committee on Science and Public Policy, & Academies, 2012), is the lack of a consistent way to measure resilience, which is a complex systems concept, across different communities and over time. Without this measurement, evaluating the impact of projects, programs and policies on a community's resilience cannot be consistently made. In turn, the relative costs and benefits of potential interventions cannot be properly assessed to determine those which ought to be prioritized. The measurement of resilience contains both theoretical and practical components, but much of the research to date has been limited to the theoretical realm. There is a need for a set of indicators that can be systematically collected in the field to practically measure resilience. This presentation will examine both the theoretical and practical challenges this involves, and how this is being approached through a unique alliance between the research community, a private partner and field practitioners. We aim to help build consistency amongst those working on assessing and prioritizing effective resilience strategies. The Alliance between research partners and NGOs will be highlighted to show how such collaborations can support a continuous learning process in communities and contribute to improved flood resilience at community level and beyond. This includes the development and use of innovative evaluation tools that can aid communities in prioritizing projects and policies as well as demonstrating effectiveness to donors.

Extrusion and rheology of fine particulate ceramic pastes

NASA Astrophysics Data System (ADS)

Mazzeo, Fred Anthony

A rheological study was conducted on an extruded blend of two alumina powders, Alcoa A-3500-SG and Reynolds ERC. These extruded blends were mixed in four compositions, varying in distribution modulus. This work focuses on the interaction of the composition components, mainly particle size distribution and amount of water at a constant binder amount. The rheological parameters of extruded pastes, Sigma, Tau, alpha and beta, were determined by using capillary rheometry modeling by the methodology set forth by Benbow and Bridgwater. This methodology makes use of capillary rheometer to determine extrusion parameters, which describe the flow behavior of a paste. The parameter values are indirectly determined by extrapolating high shear rate information obtained by the extrusion process. A goal of this research was to determine fundamental rheological properties directly from fundamental rheological equations of state. This was accomplished by assessing the material properties by using a dynamic stress rheometer. The rheological parameters used in this study to characterize the paste are elastic modulus, viscosity, tan delta, and relaxation time. This technique approaches a step closer in understanding the microstructural influence on flow behavior of a paste. This method directly determines rheological properties by using linear viscoelastic theory, giving a quantitative analysis of material properties. A strong correlation between the elastic modulus and sigma, and viscosity and alpha is shown to exist, indicating a relationship between these two techniques. Predictive process control methodology, based on particle packing modeling, quantitatively determined structural parameters useful in evaluating a composition. The determined parameters are: distribution modulus, interparticle separation distance, porosity, and particle crowding index, which are important to understand the extrudates packed state. A connection between the physical structure of the extrudate and its rheological behavior, can lead to a better understanding of what conditions and parameters are necessary to characterize the extrusion process. This study shows how particle packing and particle size influences the rheological behavior of the paste. Results showed that an optimally packed system was found to occur at a distribution modulus of 0.51. This system was determined both experimentally and quantitatively to exhibit the lowest porosity at any water content. The 0.51 system required a lower amount of water to extrude and the parameters of both rheological techniques agreed well, in which all parameters are influenced by the packing state of the paste, and a consistent trend was generally found. The capillary rheometry results can be explained by the strong interaction of particles that occurs at high shear rates. The dynamic stress rheometer results can be explained by the particle packing characteristics, interparticle separation distance and particle-crowding index, and the capillary forces between particles. The excess amount of liquid that is present in the structure decreases the role of the capillary attraction between particles and an increase in the particle size role on the rheological behavior of the pastes occurs.

Effect of Li level, artificial aging, and TiB2 reinforcement on the modulus of Weldalite (tm) 049

NASA Technical Reports Server (NTRS)

1991-01-01

The dynamic Young's Modulus (E) was determined for (1) alloys 049(1.3)(heat 072), (2) 049(1.9), and (3) 049(1.3) TiB2 in the T3 temper and after aging at 160 C were made on a single 0.953 cm (0.375 in) cube to reduce scatter from microstructural inhomogeneities. Both shear and transverse wave velocities were measured for the L, LT, and ST directions by a pulse echo technique. These velocities were then used to calculate modulus. The change is shown in E with aging time at 160 C (320 F) for the three alloys. It is clear from the plots that aging has a minor, but measurable, influence on the E of alloys 049(1.3) and 049(1.9): E decreases by -2.5 pct. for 2 and 3 during the initial stages of artificial aging. This decrease in E generally follows the strength reversion. On further aging beyond the reversion well, E increases and then decreases again as the alloy overage. The slightly higher modulus in the T8 than in the T3 temper is consistent with the presence of the high modulus T sub 1 phase in the T8 temper. A similar change in E was observed on aging for the TiB2 reinforced variant that also follows the aging curve.

Ageing effects on the diameter, nanomechanical properties and tactile perception of human hair.

PubMed

Tang, W; Zhang, S G; Zhang, J K; Chen, S; Zhu, H; Ge, S R

2016-04-01

The typical changes to hair associated with ageing are greying, thinning, dryness and brittleness. Research on the influence of ageing on hair properties will enable a detailed understanding of the natural ageing process. The studies were carried out using an SEM (scanning electron microscope), a TriboIndenter and an artificial finger. Three characteristic features of tactile perception that could reflect the perceptual dimensions of the fineness, roughness and slipperiness of hair were extracted. The influences of ageing on the diameter, surface topography, nanomechanical properties and tactile perception of hair were determined. In the three age group hair samples, the children's group hair samples have the smallest diameter. The hair cuticles in the children and young adult groups were relatively complete and less damaged than in the elderly group. The hardness and elastic modulus of the young adult group's hair samples were higher than those in the elderly and children's groups. For all groups, loss modulus E" was smaller than storage modulus E'. Vertical deviations (R) and coefficient of friction (μ) increased, and spectral centroid (SC) decreased, with the increase in age. Ageing decreased the tactile perception of hair. Ageing influences the diameter, surface topography, hardness, loss modulus, storage modulus and tactile perception of human hair. © 2015 Society of Cosmetic Scientists and the Société Française de Cosmétologie.

Hooke's Law and the Stiffness of a Plastic Spoon

NASA Astrophysics Data System (ADS)

Pestka, Kenneth A.; Warren, Cori

2012-11-01

The study of elastic properties of solids is essential to both physics and engineering. Finding simple, easy-to-visualize examples to demonstrate these concepts is often difficult. In a previous article written by one of us (KAPII), a simple method for determining Youngs modulus using marshmallows was given. In this article we will illustrate another method to explore elastic properties of everyday materials. This experiment uses a common plastic spoon exposed to a transverse force in order to determine the stiffness constant, yield point, and rupture point of the plastic spoon. In addition, much like the "Youngs Modulus of a Marshmallow" activity, this experiment visually demonstrates Hooke's law, is fun and easy to perform, and leaves a lasting impression on the students.

Quantum chemical determination of Young's modulus of lignin. Calculations on a beta-O-4' model compound.

PubMed

Elder, Thomas

2007-11-01

The calculation of Young's modulus of lignin has been examined by subjecting a dimeric model compound to strain, coupled with the determination of energy and stress. The computational results, derived from quantum chemical calculations, are in agreement with available experimental results. Changes in geometry indicate that modifications in dihedral angles occur in response to linear strain. At larger levels of strain, bond rupture is evidenced by abrupt changes in energy, structure, and charge. Based on the current calculations, the bond scission may be occurring through a homolytic reaction between aliphatic carbon atoms. These results may have implications in the reactivity of lignin especially when subjected to processing methods that place large mechanical forces on the structure.

Relation between stability and resilience determines the performance of early warning signals under different environmental drivers.

PubMed

Dai, Lei; Korolev, Kirill S; Gore, Jeff

2015-08-11

Shifting patterns of temporal fluctuations have been found to signal critical transitions in a variety of systems, from ecological communities to human physiology. However, failure of these early warning signals in some systems calls for a better understanding of their limitations. In particular, little is known about the generality of early warning signals in different deteriorating environments. In this study, we characterized how multiple environmental drivers influence the dynamics of laboratory yeast populations, which was previously shown to display alternative stable states [Dai et al., Science, 2012]. We observed that both the coefficient of variation and autocorrelation increased before population collapse in two slowly deteriorating environments, one with a rising death rate and the other one with decreasing nutrient availability. We compared the performance of early warning signals across multiple environments as "indicators for loss of resilience." We find that the varying performance is determined by how a system responds to changes in a specific driver, which can be captured by a relation between stability (recovery rate) and resilience (size of the basin of attraction). Furthermore, we demonstrate that the positive correlation between stability and resilience, as the essential assumption of indicators based on critical slowing down, can break down in this system when multiple environmental drivers are changed simultaneously. Our results suggest that the stability-resilience relation needs to be better understood for the application of early warning signals in different scenarios.

Relation between stability and resilience determines the performance of early warning signals under different environmental drivers

PubMed Central

Dai, Lei; Korolev, Kirill S.; Gore, Jeff

2015-01-01

Shifting patterns of temporal fluctuations have been found to signal critical transitions in a variety of systems, from ecological communities to human physiology. However, failure of these early warning signals in some systems calls for a better understanding of their limitations. In particular, little is known about the generality of early warning signals in different deteriorating environments. In this study, we characterized how multiple environmental drivers influence the dynamics of laboratory yeast populations, which was previously shown to display alternative stable states [Dai et al., Science, 2012]. We observed that both the coefficient of variation and autocorrelation increased before population collapse in two slowly deteriorating environments, one with a rising death rate and the other one with decreasing nutrient availability. We compared the performance of early warning signals across multiple environments as “indicators for loss of resilience.” We find that the varying performance is determined by how a system responds to changes in a specific driver, which can be captured by a relation between stability (recovery rate) and resilience (size of the basin of attraction). Furthermore, we demonstrate that the positive correlation between stability and resilience, as the essential assumption of indicators based on critical slowing down, can break down in this system when multiple environmental drivers are changed simultaneously. Our results suggest that the stability–resilience relation needs to be better understood for the application of early warning signals in different scenarios. PMID:26216946

Increased Upper Trapezius Muscle Stiffness in Overhead Athletes with Rotator Cuff Tendinopathy

PubMed Central

Leong, Hio Teng; Hug, François; Fu, Siu Ngor

2016-01-01

Although excessive tension of the upper trapezius (UT) is thought to contribute to rotator cuff tendinopathy, no study examined UT tension in athletes with and without rotator cuff tendinopathy. Here we used UT shear modulus measured using ultrasound shear wave elastography as an index of muscle stiffness/tension. The aims of this study were twofold: 1) to determine whether the UT muscle shear modulus is altered in athletes with rotator cuff tendinopathy compared to asymptomatic athletes, and 2) to detect optimal cut-off points of UT shear modulus in identifying athletes with rotator cuff tendinopathy. Forty-three male volleyball players (17 asymptomatic and 26 with rotator cuff tendinopathy, mean age = 22.9±3.5 years) participated in the study. UT shear modulus was quantified during active arm holding at 30° and 60° of shoulder abduction and passive arm positioning at 0°, 30° and 60° of shoulder abduction. During the active tasks, the UT shear modulus was higher in athletes with rotator cuff tendinopathy than the asymptomatic athletes (p = 0.002), regardless the arm position. During the passive tasks, athletes with rotator cuff tendinopathy exhibited a higher UT shear modulus than asymptomatic athletes only at 0° of shoulder abduction (13.0±2.5 kPa vs 10.2±1.8 kPa, p = 0.001). When considering the active task, an optimal cut-off shear modulus of 12.0 kPa at 30° of shoulder abduction (sensitivity = 0.84, specificity = 0.57, AUC = 0.757, p = 0.008) and 9.5 kPa at 60° of shoulder abduction (sensitivity = 0.88, specificity = 0.67, AUC = 0.816, p = 0.002) was detected. When considering the passive task at 0° of shoulder abduction, a cut-off of 12.2 kPa was found (sensitivity = 0.73, AUC = 0.817, p = 0.001). Findings from the present study show that monitoring passive and active UT muscle shear modulus may provide important information for the prevention/rehabilitation of rotator cuff tendinopathy. PMID:27159276

Increased Upper Trapezius Muscle Stiffness in Overhead Athletes with Rotator Cuff Tendinopathy.

PubMed

Leong, Hio Teng; Hug, François; Fu, Siu Ngor

2016-01-01

Although excessive tension of the upper trapezius (UT) is thought to contribute to rotator cuff tendinopathy, no study examined UT tension in athletes with and without rotator cuff tendinopathy. Here we used UT shear modulus measured using ultrasound shear wave elastography as an index of muscle stiffness/tension. The aims of this study were twofold: 1) to determine whether the UT muscle shear modulus is altered in athletes with rotator cuff tendinopathy compared to asymptomatic athletes, and 2) to detect optimal cut-off points of UT shear modulus in identifying athletes with rotator cuff tendinopathy. Forty-three male volleyball players (17 asymptomatic and 26 with rotator cuff tendinopathy, mean age = 22.9±3.5 years) participated in the study. UT shear modulus was quantified during active arm holding at 30° and 60° of shoulder abduction and passive arm positioning at 0°, 30° and 60° of shoulder abduction. During the active tasks, the UT shear modulus was higher in athletes with rotator cuff tendinopathy than the asymptomatic athletes (p = 0.002), regardless the arm position. During the passive tasks, athletes with rotator cuff tendinopathy exhibited a higher UT shear modulus than asymptomatic athletes only at 0° of shoulder abduction (13.0±2.5 kPa vs 10.2±1.8 kPa, p = 0.001). When considering the active task, an optimal cut-off shear modulus of 12.0 kPa at 30° of shoulder abduction (sensitivity = 0.84, specificity = 0.57, AUC = 0.757, p = 0.008) and 9.5 kPa at 60° of shoulder abduction (sensitivity = 0.88, specificity = 0.67, AUC = 0.816, p = 0.002) was detected. When considering the passive task at 0° of shoulder abduction, a cut-off of 12.2 kPa was found (sensitivity = 0.73, AUC = 0.817, p = 0.001). Findings from the present study show that monitoring passive and active UT muscle shear modulus may provide important information for the prevention/rehabilitation of rotator cuff tendinopathy.

Sustainability and resilience in midwifery: A discussion paper.

PubMed

Crowther, Susan; Hunter, Billie; McAra-Couper, Judith; Warren, Lucie; Gilkison, Andrea; Hunter, Marion; Fielder, Anna; Kirkham, Mavis

2016-09-01

midwifery workforce issues are of international concern. Sustainable midwifery practice, and how resilience is a required quality for midwives, have begun to be researched. How these concepts are helpful to midwifery continues to be debated. It is important that such debates are framed so they can be empowering for midwives. Care is required not to conceptually label matters concerning the midwifery workforce without judicious scrutiny and diligence. the aim of this discussion paper is to explore the concepts of sustainability and resilience now being suggested in midwifery workforce literature. Whether sustainability and resilience are concepts useful in midwifery workforce development is questioned. using published primary midwifery research from United Kingdom and New Zealand the concepts of sustainability and resilience are compared, contrasted and explored. there are obvious differences in models of midwifery care in the United Kingdom and New Zealand. Despite these differences, the concepts of resilience and sustainability emerge as overlapping themes from the respective studies' findings. Comparison between studies provides evidence of what is crucial in sustaining healthy resilient midwifery practice. Four common themes have been identified that traverse the different models of care; Self-determination, ability to self-care, cultivation of relationships both professionally and with women/families, and a passion, joy and love for midwifery. the impact that midwifery models of care may have on sustainable practice and nurturing healthy resilient behaviors remains uncertain. The notion of resilience in midwifery as the panacea to resolve current concerns may need rethinking. Resilience may be interpreted as expecting midwives 'to toughen up' in a workplace setting that is socially, economically and culturally challenging. Sustainability calls for examination of the reciprocity between environments of working and the individual midwife. The findings invite further examination of contextual influences that affect the wellbeing of midwives across different models of care. Crown Copyright © 2016. Published by Elsevier Ltd. All rights reserved.

Experimental and Theoretical Modal Analysis of Full-Sized Wood Composite Panels Supported on Four Nodes

PubMed Central

Guan, Cheng; Zhang, Houjiang; Wang, Xiping; Miao, Hu; Zhou, Lujing; Liu, Fenglu

2017-01-01

Key elastic properties of full-sized wood composite panels (WCPs) must be accurately determined not only for safety, but also serviceability demands. In this study, the modal parameters of full-sized WCPs supported on four nodes were analyzed for determining the modulus of elasticity (E) in both major and minor axes, as well as the in-plane shear modulus of panels by using a vibration testing method. The experimental modal analysis was conducted on three full-sized medium-density fiberboard (MDF) and three full-sized particleboard (PB) panels of three different thicknesses (12, 15, and 18 mm). The natural frequencies and mode shapes of the first nine modes of vibration were determined. Results from experimental modal testing were compared with the results of a theoretical modal analysis. A sensitivity analysis was performed to identify the sensitive modes for calculating E (major axis: Ex and minor axis: Ey) and the in-plane shear modulus (Gxy) of the panels. Mode shapes of the MDF and PB panels obtained from modal testing are in a good agreement with those from theoretical modal analyses. A strong linear relationship exists between the measured natural frequencies and the calculated frequencies. The frequencies of modes (2, 0), (0, 2), and (2, 1) under the four-node support condition were determined as the characteristic frequencies for calculation of Ex, Ey, and Gxy of full-sized WCPs. The results of this study indicate that the four-node support can be used in free vibration test to determine the elastic properties of full-sized WCPs. PMID:28773043

Mechanical Properties of Uranium Silicides by Nanoindentation and Finite Elements Modeling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carvajal-Nunez, U.; Elbakhshwan, M. S.; Mara, N. A.

Three methods were used to measure the mechanical properties of U 3Si, U 3Si 2, and USi. Quasi-static and continuous stiffness measurement nanoindentation were used to determine hardness and Young’s modulus, and microindentation was used to evaluate the bulk hardness. Hardness and Young’s modulus of the three U-Si compounds were both observed to increase with Si content. In conclusion, finite elements modelling was used to validate the nanoindentation data calculated for U 3Si 2 and estimate its yield strength.

Mechanical Properties of Uranium Silicides by Nanoindentation and Finite Elements Modeling

DOE PAGES

Carvajal-Nunez, U.; Elbakhshwan, M. S.; Mara, N. A.; ...

2017-12-04

Three methods were used to measure the mechanical properties of U 3Si, U 3Si 2, and USi. Quasi-static and continuous stiffness measurement nanoindentation were used to determine hardness and Young’s modulus, and microindentation was used to evaluate the bulk hardness. Hardness and Young’s modulus of the three U-Si compounds were both observed to increase with Si content. In conclusion, finite elements modelling was used to validate the nanoindentation data calculated for U 3Si 2 and estimate its yield strength.

Mechanical properties of metal-organic frameworks: An indentation study on epitaxial thin films

NASA Astrophysics Data System (ADS)

Bundschuh, S.; Kraft, O.; Arslan, H. K.; Gliemann, H.; Weidler, P. G.; Wöll, C.

2012-09-01

We have determined the hardness and Young's modulus of a highly porous metal-organic framework (MOF) using a standard nanoindentation technique. Despite the very low density of these films, 1.22 g cm-3, Young's modulus reaches values of almost 10 GPa for HKUST-1, demonstrating that this porous coordination polymer is substantially stiffer than normal polymers. This progress in characterizing mechanical properties of MOFs has been made possible by the use of high quality, oriented thin films grown using liquid phase epitaxy on modified Au substrates.

Polymer blends for LDB applications. [Long Duration Ballooning

NASA Technical Reports Server (NTRS)

Lichkus, Andrew M.; Harrison, Ian R.

1991-01-01

A series of LCP/PE blends have been studied to determine the potential of such systems to produce a high modulus balloon film material which retains the balloon fabrication and low temperature flight advantages of the current PE films. Blown films of blends of 5 and 15 percent LCP in PE have been produced which show a 28 percent enhancement in modulus over the neat PE matrix. These results are substantially lower than anticipated and are explained in terms of the LCP reinforcement aspect ratio and fibril diameter.

Natural asphalt modified binders used for high stiffness modulus asphalt concrete

NASA Astrophysics Data System (ADS)

Bilski, Marcin; Słowik, Mieczysław

2018-05-01

This paper presents a set of test results supporting the possibility of replacing, in Polish climate conditions, hard road 20/30 penetration grade bitumen used in the binder course and/or base course made of high stiffness modulus asphalt concrete with binders comprising of 35/50 or 50/70 penetration grade bitumens and additives in the form of natural Gilsonite or Trinidad Epuré asphalts. For the purpose of comparing the properties of the discussed asphalt binders, values of the Performance Grade have been determined according to the American Superpave system criteria.

Structure-Property Relationships of Bismaleimides

NASA Technical Reports Server (NTRS)

Tenteris-Noebe, Anita D.

1997-01-01

The purpose of this research was to control and systematically vary the network topology of bismaleimides through cure temperature and chemistry (addition of various coreactants) and subsequently attempt to determine structure-mechanical property relationships. Characterization of the bismaleimide structures by dielectric, rheological, and thermal analyses, and density measurements was subsequently correlated with mechanical properties such as modulus, yield strength, fracture energy, and stress relaxation. The model material used in this investigation was 4,4'-BismaleiMidodIphenyl methane (BMI). BMI was coreacted with either 4,4'-Methylene Dianiline (MDA), o,o'-diallyl bisphenol A (DABA) from Ciba Geigy, or Diamino Diphenyl Sulfone (DDS). Three cure paths were employed: a low- temperature cure of 140 C where chain extension should predominate, a high-temperature cure of 220 C where both chain extension and crosslinking should occur simultaneously, and a low-temperature (140 C) cure followed immediately by a high-temperature (220 C) cure where the chain extension reaction or amine addition precedes BMI homopolymerization or crosslinking. Samples of cured and postcured PMR-15 were also tested to determine the effects of postcuring on the mechanical properties. The low-temperature cure condition of BMI/MDA exhibited the highest modulus values for a given mole fraction of BMI with the modulus decreasing with decreasing concentration of BMI. The higher elastic modulus is the result of steric hindrance by unreacted BMI molecules in the glassy state. The moduli values for the high- and low/high-temperature cure conditions of BMI/MDA decreased as the amount of diamine increased. All the moduli values mimic the yield strength and density trends. For the high-temperature cure condition, the room- temperature modulus remained constant with decreasing mole fraction of BMT for the BMI/DABA and BMI/DDS systems. Postcuring PMR-15 increases the modulus over that of the cured material even though density values of cured and postcured PMR were essentially the same. Preliminary results of a continuous and intermittent stress relaxation experiment for BMI:MDA in a 2:1 molar ratio indicate that crosslinking is occurring when the sample is in the undeformed state. Computer simulation of properties such as density, glass transition temperature, and modulus for the low- temperature cure conditions of BMI/MDA and BMI/DABA were completed. The computer modeling was used to help further understand and confirm the structure characterization results. The simulations correctly predicted the trends of these properties versus mole fraction BMI and were extended to other BMI/diamine systems.

Developing measurement indices to enhance protection and resilience of critical infrastructure and key resources.

PubMed

Fisher, Ronald E; Norman, Michael

2010-07-01

The US Department of Homeland Security (DHS) is developing indices to better assist in the risk management of critical infrastructures. The first of these indices is the Protective Measures Index - a quantitative index that measures overall protection across component categories: physical security, security management, security force, information sharing, protective measures and dependencies. The Protective Measures Index, which can also be recalculated as the Vulnerability Index, is a way to compare differing protective measures (eg fence versus security training). The second of these indices is the Resilience Index, which assesses a site's resilience and consists of three primary components: robustness, resourcefulness and recovery. The third index is the Criticality Index, which assesses the importance of a facility. The Criticality Index includes economic, human, governance and mass evacuation impacts. The Protective Measures Index, Resilience Index and Criticality Index are being developed as part of the Enhanced Critical Infrastructure Protection initiative that DHS protective security advisers implement across the nation at critical facilities. This paper describes two core themes: determination of the vulnerability, resilience and criticality of a facility and comparison of the indices at different facilities.

Dynamics of Lung Defense in Pneumonia: Resistance, Resilience, and Remodeling

PubMed Central

Quinton, Lee J.; Mizgerd, Joseph P.

2015-01-01

Pneumonia is initiated by microbes in the lung, but physiological processes integrating responses across diverse cell types and organ systems dictate the outcome of respiratory infection. Resistance, or actions of the host to eradicate living microbes, in the lungs involves a combination of innate and adaptive immune responses triggered by air-space infection. Resilience, or the ability of the host tissues to withstand the physiologically damaging effects of microbial and immune activities, is equally complex, precisely regulated, and determinative. Both immune resistance and tissue resilience are dynamic and change throughout the lifetime, but we are only beginning to understand such remodeling and how it contributes to the incidence of severe pneumonias, which diminishes as childhood progresses and then increases again among the elderly. Here, we review the concepts of resistance, resilience, and remodeling as they apply to pneumonia, highlighting recent advances and current significant knowledge gaps. PMID:25148693

Resilient filtering for time-varying stochastic coupling networks under the event-triggering scheduling

NASA Astrophysics Data System (ADS)

Wang, Fan; Liang, Jinling; Dobaie, Abdullah M.

2018-07-01

The resilient filtering problem is considered for a class of time-varying networks with stochastic coupling strengths. An event-triggered strategy is adopted to save the network resources by scheduling the signal transmission from the sensors to the filters based on certain prescribed rules. Moreover, the filter parameters to be designed are subject to gain perturbations. The primary aim of the addressed problem is to determine a resilient filter that ensures an acceptable filtering performance for the considered network with event-triggering scheduling. To handle such an issue, an upper bound on the estimation error variance is established for each node according to the stochastic analysis. Subsequently, the resilient filter is designed by locally minimizing the derived upper bound at each iteration. Moreover, rigorous analysis shows the monotonicity of the minimal upper bound regarding the triggering threshold. Finally, a simulation example is presented to show effectiveness of the established filter scheme.

Conceptualizing Holistic Community Resilience to Climate ...

EPA Pesticide Factsheets

The concept of resilience has been evolving over the past decade as a way to address the current and future challenges nations, states, and cities face from a changing climate. Understanding how the environment (natural and built), climate event risk, societal interactions, and governance reflect community resilience for adaptive management is critical for envisioning urban and natural environments that can persist through extreme weather events and longer-term shifts in climate. To be successful, this interaction of these five domains must result in maintaining quality of life and ensuring equal access to the benefits or the protection from harm for all segments of the population. An exhaustive literature review of climate resilience approaches was conducted examining the two primary elements of resilience—vulnerability and recoverability. The results of this review were examined to determine if any existing frameworks addressed the above five major areas in an integrated manner. While some aspects of a resilience model were available for existing sources, no comprehensive approach was available. A new conceptual model for resilience to climate events is proposed that incorporates some available structures and addresses these five domains at a national, regional, state, and county spatial scale for a variety of climate-induced events ranging from superstorms to droughts and their concomitant events such as wildfires, floods, and pest invasions. This conceptua

Positive and Negative Emotion Prospectively Predict Trajectories of Resilience and Distress Among High-Exposure Police Officers

PubMed Central

Galatzer-Levy, Isaac R.; Brown, Adam D.; Henn-Haase, Clare; Metzler, Thomas J.; Neylan, Thomas C.; Marmar, Charles R.

2013-01-01

Responses to both potentially traumatic events and other significant life stressors have been shown to conform to discrete patterns of response such as resilience, anticipatory stress, initial distress with gradual recovery, and chronic distress. The etiology of these trajectories is still unclear. Individual differences in levels of negative and positive emotion are believed to play a role in determining risk and resilience following traumatic exposure. In the current investigation, we followed police officers prospectively from academy training through 48 months of active duty, assessing levels of distress every 12 months. Using latent class growth analysis, we identified 4 trajectories closely conforming to prototypical patterns. Furthermore, we found that lower levels of self-reported negative emotion during academy training prospectively predicted membership in the resilient trajectory compared with the more symptomatic trajectories following the initiation of active duty, whereas higher levels of positive emotion during academy training differentiated resilience from a trajectory that was equivalently low on distress during academy training but consistently grew in distress through 4 years of active duty. These findings emerging from a prospective longitudinal design provide evidence that resilience is predicted by both lower levels of negative emotion and higher levels of positive emotion prior to active duty stressor exposure. PMID:23339621

Influence of nanofillers on the thermal and mechanical behavior of DGEBA-based adhesives for bonded-in timber connections

NASA Astrophysics Data System (ADS)

Ahmad, Z.; Ansell, M. P.; Smedley, D.

2006-09-01

Results of an experimental investigation into the thermal behavior and mechanical properties of a room-temperature-cured epoxy adhesive (diglycidyl ether of bisphenol A, DGEBA) cross-linked with polyetheramines and filled with different fillers, namely nanosilica, liquid rubber (CTBN), and clay, are reported. The nanosilica and liquid rubber increased the flexural strength and elastic modulus of the adhesive systems; the addition of clay particles raised the elastic modulus significantly, but embrittled the adhesive. Establishing a correct cure time is very important for bonded-in timber structures, as it will affect the bond strength. A study on the effect of cure time on the flexural strength was carried out, from which it follows that the adhesives should be cured for at least 20 days at room temperature. The damping characteristics and the glass-transition temperature of the adhesives were determined by using a dynamic mechanical thermal analysis. The results showed that the filled adhesives had a higher storage modulus, which was in agreement with the elastic moduli determined from static bending tests. The introduction of the fillers increased its glass-transition temperature considerably.

Resilience: Theory and Application.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carlson, J.L.; Haffenden, R.A.; Bassett, G.W.

2012-02-03

There is strong agreement among policymakers, practitioners, and academic researchers that the concept of resilience must play a major role in assessing the extent to which various entities - critical infrastructure owners and operators, communities, regions, and the Nation - are prepared to respond to and recover from the full range of threats they face. Despite this agreement, consensus regarding important issues, such as how resilience should be defined, assessed, and measured, is lacking. The analysis presented here is part of a broader research effort to develop and implement assessments of resilience at the asset/facility and community/regional levels. The literaturemore » contains various definitions of resilience. Some studies have defined resilience as the ability of an entity to recover, or 'bounce back,' from the adverse effects of a natural or manmade threat. Such a definition assumes that actions taken prior to the occurrence of an adverse event - actions typically associated with resistance and anticipation - are not properly included as determinants of resilience. Other analyses, in contrast, include one or more of these actions in their definitions. To accommodate these different definitions, we recognize a subset of resistance- and anticipation-related actions that are taken based on the assumption that an adverse event is going to occur. Such actions are in the domain of resilience because they reduce both the immediate and longer-term adverse consequences that result from an adverse event. Recognizing resistance- and anticipation-related actions that take the adverse event as a given accommodates the set of resilience-related actions in a clear-cut manner. With these considerations in mind, resilience can be defined as: 'the ability of an entity - e.g., asset, organization, community, region - to anticipate, resist, absorb, respond to, adapt to, and recover from a disturbance.' Because critical infrastructure resilience is important both in its own right and because of its implications for community/regional resilience, it is especially important to develop a sound methodology for assessing resilience at the asset/facility level. This objective will be accomplished by collecting data on four broadly defined groups of resilience-enhancing measures: preparedness, mitigation measures, response capabilities, and recovery mechanisms. Table ES-1 illustrates how the six components that define resilience are connected to the actions that enhance the capacity of an entity to be resilient. The relationships illustrated in Table ES-1 provide the framework for developing a survey instrument that will be used to elicit the information required to assess resilience at the asset/facility level. The resilience of a community/region is a function of the resilience of its subsystems, including its critical infrastructures, economy, civil society, governance (including emergency services), and supply chains/dependencies. The number and complexity of these subsystems will make the measurement of resilience more challenging as we move from individual assets/facilities to the community/regional level (where critical infrastructure resilience is only one component). Specific challenges include uncertainty about relationships (e.g., the composition of specific supply chains), data gaps, and time and budget constraints that prevent collection of all of the information needed to construct a comprehensive assessment of the resilience of a specific community or region. These challenges can be addressed, at least partially, by adopting a 'systems approach' to the assessment of resilience. In a systems approach, the extent to which the analysis addresses the resilience of the individual subsystems can vary. Specifically, high-level systems analysis can be used to identify the most important lower-level systems. In turn, within the most important lower-level systems, site assessment data should be collected only on the most critical asset-level components about which the least is known. Implementation of the strategies outlined here to assess resilience will facilitate the following four objectives: (1) Develop a methodology and supporting products to assess resilience at the asset/facility level, (2) Develop a methodology and supporting products to assess resilience at the critical infrastructure sector level, (3) Provide resilience-related information to critical infrastructure owners/operators to facilitate risk-based resource decision making, and (4) Provide resilience-related information to State and local mission partners to support their risk-based resource decision making.« less

Finite Element Analysis of Single Cell Stiffness Measurements Using PZT-Integrated Buckling Nanoneedles.

PubMed

Rad, Maryam Alsadat; Tijjani, Auwal Shehu; Ahmad, Mohd Ridzuan; Auwal, Shehu Muhammad

2016-12-23

This paper proposes a new technique for real-time single cell stiffness measurement using lead zirconate titanate (PZT)-integrated buckling nanoneedles. The PZT and the buckling part of the nanoneedle have been modelled and validated using the ABAQUS software. The two parts are integrated together to function as a single unit. After calibration, the stiffness, Young's modulus, Poisson's ratio and sensitivity of the PZT-integrated buckling nanoneedle have been determined to be 0.7100 N·m -1 , 123.4700 GPa, 0.3000 and 0.0693 V·m·N -1 , respectively. Three Saccharomyces cerevisiae cells have been modelled and validated based on compression tests. The average global stiffness and Young's modulus of the cells are determined to be 10.8867 ± 0.0094 N·m -1 and 110.7033 ± 0.0081 MPa, respectively. The nanoneedle and the cell have been assembled to measure the local stiffness of the single Saccharomyces cerevisiae cells The local stiffness, Young's modulus and PZT output voltage of the three different size Saccharomyces cerevisiae have been determined at different environmental conditions. We investigated that, at low temperature the stiffness value is low to adapt to the change in the environmental condition. As a result, Saccharomyces cerevisiae becomes vulnerable to viral and bacterial attacks. Therefore, the proposed technique will serve as a quick and accurate process to diagnose diseases at early stage in a cell for effective treatment.

Effective properties of dispersed phase reinforced composite materials with perfect and imperfect interfaces

NASA Astrophysics Data System (ADS)

Han, Ru

This thesis focuses on the analysis of dispersed phase reinforced composite materials with perfect as well as imperfect interfaces using the Boundary Element Method (BEM). Two problems of interest are considered, namely, to determine the limitations in the use of effective properties and the analysis of failure progression at the inclusion-matrix interface. The effective moduli (effective Young's modulus, effective Poisson's ratio, effective shear modulus, and effective bulk modulus) of composite materials can be determined at the mesoscopic level using three-dimensional parallel BEM simulations. By comparing the mesoscopic BEM results and the macroscopic results based on effective properties, limitations in the effective property approach can be determined. Decohesion is an important failure mode associated with fiber-reinforced composite materials. Analysis of failure progression at the fiber-matrix interface in fiber-reinforced composite materials is considered using a softening decohesion model consistent with thermodynamic concepts. In this model, the initiation of failure is given directly by a failure criterion. Damage is interpreted by the development of a discontinuity of displacement. The formulation describing the potential development of damage is governed by a discrete decohesive constitutive equation. Numerical simulations are performed using the direct boundary element method. Incremental decohesion simulations illustrate the progressive evolution of debonding zones and the propagation of cracks along the interfaces. The effect of decohesion on the macroscopic response of composite materials is also investigated.

An evaluation of the Iosipescu specimen for composite materials shear property measurement

NASA Technical Reports Server (NTRS)

Morton, J.; Ho, H.; Tsai, M. Y.; Farley, G. L.

1992-01-01

A detailed evaluation of the suitability of the Iosipescu specimen tested in the modified Wyoming fixture is presented. A linear finite element model of the specimen is used to assess the uniformity of the shear stress field in the vicinity of the notch, and demonstrate the effect of the nonuniform stress field upon strain gage measurements used for the determination of composite shear moduli. Based upon test results from graphite-epoxy laminates, the proximity of the load introduction point to the test section and the material orthotropy greatly influence the individual gage readings, however, shear modulus determination is not significantly affected by the lack of pure shear. Correction factors are needed to allow for the nonuniformity of the strain field and the use of the average shear stress in the shear modulus evaluation. The correction factors are determined for the region occupied by the strain gage rosette. A comparison of the strain gage readings from one surface of a specimen with corresponding data from moire interferometry on the opposite face documented an extreme sensitivity of some fiber orientations to eccentric loading which induced twisting and spurious shear stress-strain curves. The discovery of specimen twisting explains the apparently inconsistent shear property data found in the literature. Recommendations for improving the reliability and accuracy of the shear modulus values are made, and the implications for shear strength measurement discussed.

Effective Biot theory and its generalization to poroviscoelastic models

NASA Astrophysics Data System (ADS)

Liu, Xu; Greenhalgh, Stewart; Zhou, Bing; Greenhalgh, Mark

2018-02-01

A method is suggested to express the effective bulk modulus of the solid frame of a poroelastic material as a function of the saturated bulk modulus. This method enables effective Biot theory to be described through the use of seismic dispersion measurements or other models developed for the effective saturated bulk modulus. The effective Biot theory is generalized to a poroviscoelastic model of which the moduli are represented by the relaxation functions of the generalized fractional Zener model. The latter covers the general Zener and the Cole-Cole models as special cases. A global search method is described to determine the parameters of the relaxation functions, and a simple deterministic method is also developed to find the defining parameters of the single Cole-Cole model. These methods enable poroviscoelastic models to be constructed, which are based on measured seismic attenuation functions, and ensure that the model dispersion characteristics match the observations.

Biocompatible low Young's modulus achieved by strong crystallographic elastic anisotropy in Ti-15Mo-5Zr-3Al alloy single crystal.

PubMed

Lee, S-H; Todai, M; Tane, M; Hagihara, K; Nakajima, H; Nakano, T

2012-10-01

The elastic anisotropy of the Ti-15Mo-5Zr-3Al (mass%) β-Ti alloy, an ISO certified biomedical material, was investigated using its single crystal. It was revealed that the Young's modulus exhibited pronounced anisotropy. The Young's modulus was reduced to 44.4GPa along the 〈100〉 direction in the Ti-15Mo-5Zr-3Al single crystal, that is comparable to that of human cortical bones. We determined the strategy that β-Ti alloys with extremely low moduli can be developed by reducing the electron-atom (e/a) ratio in alloys, and by suppressing the formation of the ω-phase at the same time. This new knowledge must lead to the development of "single crystalline β-Ti implant materials" as hard tissue replacements for reducing the stress shielding effect. Copyright © 2012 Elsevier Ltd. All rights reserved.

Tissue-level Mechanical Properties of Bone Contributing to Fracture Risk

PubMed Central

Nyman, Jeffry S.; Granke, Mathilde; Singleton, Robert C.; Pharr, George M.

2016-01-01

Tissue-level mechanical properties characterize mechanical behavior independently of microscopic porosity. Specifically, quasi-static nanoindentation provides measurements of modulus (stiffness) and hardness (resistance to yielding) of tissue at the length scale of the lamella, while dynamic nanoindentation assesses time-dependent behavior in the form of storage modulus (stiffness), loss modulus (dampening), and loss factor (ratio of the two). While these properties are useful in establishing how a gene, signaling pathway, or disease of interest affects bone tissue, they generally do not vary with aging after skeletal maturation or with osteoporosis. Heterogeneity in tissue-level mechanical properties or in compositional properties may contribute to fracture risk, but a consensus on whether the contribution is negative or positive has not emerged. In vivo indentation of bone tissue is now possible, and the mechanical resistance to microindentation has the potential for improving fracture risk assessment, though determinants are currently unknown. PMID:27263108

Effect of Curing Period on Properties of Steel and Polypropylene Fibre Reinforced Ultra-High Performance Concrete

NASA Astrophysics Data System (ADS)

Smarzewski, Piotr

2017-10-01

This study has investigated the effect of curing period on the mechanical properties of straight polypropylene and hooked-end steel fibre reinforced ultra-high performance concrete (UHPC). Various physical properties are evaluated, i.e. absorbability, apparent density and open porosity. Compressive strength, tensile splitting strength, flexural strength and modulus of elasticity were determined at 28, 56 and 730 days. Comparative strength development of fibre reinforced mixes at 0.5%, 1%, 1.5% and 2% by volume fractions in relation to the mix without fibres was observed. Good correlations between the compressive strength and the modulus of elasticity are established. Steel and polypropylene fibres significantly increased the compressive strength, tensile splitting strength, flexural strength and modulus of elasticity of UHPC after two years curing period when fibre content volume was at least 1%. It seems that steel fibre reinforced UHPC has better properties than the polypropylene fibre reinforced UHPC.

Tissue-Level Mechanical Properties of Bone Contributing to Fracture Risk.

PubMed

Nyman, Jeffry S; Granke, Mathilde; Singleton, Robert C; Pharr, George M

2016-08-01

Tissue-level mechanical properties characterize mechanical behavior independently of microscopic porosity. Specifically, quasi-static nanoindentation provides measurements of modulus (stiffness) and hardness (resistance to yielding) of tissue at the length scale of the lamella, while dynamic nanoindentation assesses time-dependent behavior in the form of storage modulus (stiffness), loss modulus (dampening), and loss factor (ratio of the two). While these properties are useful in establishing how a gene, signaling pathway, or disease of interest affects bone tissue, they generally do not vary with aging after skeletal maturation or with osteoporosis. Heterogeneity in tissue-level mechanical properties or in compositional properties may contribute to fracture risk, but a consensus on whether the contribution is negative or positive has not emerged. In vivo indentation of bone tissue is now possible, and the mechanical resistance to microindentation has the potential for improving fracture risk assessment, though determinants are currently unknown.

Interface test series: An in situ study of factors affecting the containment of hydraulic fractures

NASA Astrophysics Data System (ADS)

Warpinski, N. R.; Finley, S. J.; Vollendorf, W. C.; Obrien, M.; Eshom, E.

1982-02-01

In situ experiments, which are accessible for direct observation by mineback, were conducted to determine the effect that material-property interfaces and in situ stress differences have on hydraulic fracture propagation and the resultant overall geometry. These experiments show conclusively that a difference in elastic modulus at a geologic interface has little or no effect on crack growth and, therefore, is not a feature which would promote containment of fractures within a specified reservoir zone. However, differences in the in situ stress between adjacent layers is shown to have a considerable influence on fracture propagation. Experiments were conducted in a low modulus ash-fall tuff which contained two layers of high minimum principal in situ stress and which was overlain by a formation with at least a factor of 5 increase in elastic modulus. Fractures were observed to terminate in regions of high minimum principal in situ stress in nearly every case.

Nonlinear effects in thermal stress analysis of a solid propellant rocket motor

NASA Technical Reports Server (NTRS)

Francis, E. C.; Peeters, R. L.; Murch, S. A.

1976-01-01

Direct characterization procedures were used to determine the relaxation modulus as a function of time, temperature, and state of strain. Using the quasi-elastic method of linearviscoelasticity, these properties were employed in a finite element computer code to analyze a thick-walled, nonlinear viscoelastic cylinder in the state of plane strain bonded to a thin (but stiff) elastic casing and subjected to slow thermal cooling. The viscoelastic solution is then expressed as a sequence of elastic finite element solutions. The strain-dependent character of the relaxation modulus is included by replacing the single relaxation curve used in the linear viscoelastic theory by a family of relaxation functions obtained at various strain levels. These functions may be regarded as a collection of stress histories or responses to specific loads (in this case, step strains) with which the cooldown solution is made to agree by iterations on the modulus and strain level.

Effective properties of a fly ash geopolymer: Synergistic application of X-ray synchrotron tomography, nanoindentation, and homogenization models

DOE PAGES

Das, Sumanta; Yang, Pu; Singh, Sudhanshu S.; ...

2015-09-02

Microstructural and micromechanical investigation of a fly ash-based geopolymer using: (i) synchrotron x-ray tomography (XRT) to determine the volume fraction and tortuosity of pores that are influential in fluid transport, (ii) mercury intrusion porosimetry (MIP) to capture the volume fraction of smaller pores, (iii) scanning electron microscopy (SEM) combined with multi-label thresholding to identify and characterize the solid phases in the microstructure, and (iv) nanoindentation to determine the component phase elastic properties using statistical deconvolution, is reported in this paper. The phase volume fractions and elastic properties are used in multi-step mean field homogenization (Mori- Tanaka and double inclusion) modelsmore » to determine the homogenized macroscale elastic modulus of the composite. The homogenized elastic moduli are in good agreement with the flexural elastic modulus determined on macroscale paste beams. As a result, the combined use of microstructural and micromechanical characterization tools at multiple scales provides valuable information towards the material design of fly ash geopolymers.« less

Factors Affecting Resilience and Development of Posttraumatic Stress Disorder in Critical Care Nurses.

PubMed

Mealer, Meredith; Jones, Jacqueline; Meek, Paula

2017-05-01

Job stress and cumulative exposure to traumatic events experienced by critical care nurses can lead to psychological distress and the development of burnout syndrome and posttraumatic stress disorder. Resilience can mitigate symptoms associated with these conditions. To identify factors that affect resilience and to determine if the factors have direct or indirect effects on resilience in development of posttraumatic stress disorder. Data from 744 respondents to a survey mailed to 3500 critical care nurses who were members of the American Association of Critical-Care Nurses were analyzed. Mplus was used to analyze a mediation model. Nurses who worked in any type of intensive care unit other than the medical unit and had high scores for resilience were 18% to 50% less likely to experience post-traumatic stress disorder than were nurses with low scores. Nurses with a graduate degree in nursing were 18% more likely to experience posttraumatic stress disorder than were nurses with a bachelor's degree. Because of their effects on resilience, working in a medical intensive care unit and having a graduate degree may influence the development of posttraumatic stress disorder. Future research is needed to better understand the impact of resilience on health care organizations, development of preventive therapies and treatment of posttraumatic stress disorder for critical care nurses, and the most appropriate mechanism to disseminate and implement strategies to address posttraumatic stress disorder. ©2017 American Association of Critical-Care Nurses.

Validation of a Framework for Measuring Hospital Disaster Resilience Using Factor Analysis

PubMed Central

Zhong, Shuang; Clark, Michele; Hou, Xiang-Yu; Zang, Yuli; FitzGerald, Gerard

2014-01-01

Hospital disaster resilience can be defined as “the ability of hospitals to resist, absorb, and respond to the shock of disasters while maintaining and surging essential health services, and then to recover to its original state or adapt to a new one.” This article aims to provide a framework which can be used to comprehensively measure hospital disaster resilience. An evaluation framework for assessing hospital resilience was initially proposed through a systematic literature review and Modified-Delphi consultation. Eight key domains were identified: hospital safety, command, communication and cooperation system, disaster plan, resource stockpile, staff capability, disaster training and drills, emergency services and surge capability, and recovery and adaptation. The data for this study were collected from 41 tertiary hospitals in Shandong Province in China, using a specially designed questionnaire. Factor analysis was conducted to determine the underpinning structure of the framework. It identified a four-factor structure of hospital resilience, namely, emergency medical response capability (F1), disaster management mechanisms (F2), hospital infrastructural safety (F3), and disaster resources (F4). These factors displayed good internal consistency. The overall level of hospital disaster resilience (F) was calculated using the scoring model: F = 0.615F1 + 0.202F2 + 0.103F3 + 0.080F4. This validated framework provides a new way to operationalise the concept of hospital resilience, and it is also a foundation for the further development of the measurement instrument in future studies. PMID:24945190

Local Stressors, Resilience, and Shifting Baselines on Coral Reefs.

PubMed

McLean, Matthew; Cuetos-Bueno, Javier; Nedlic, Osamu; Luckymiss, Marston; Houk, Peter

2016-01-01

Understanding how and why coral reefs have changed over the last twenty to thirty years is crucial for sustaining coral-reef resilience. We used a historical baseline from Kosrae, a typical small island in Micronesia, to examine changes in fish and coral assemblages since 1986. We found that natural gradients in the spatial distribution of fish and coral assemblages have become amplified, as island geography is now a stronger determinant of species abundance patterns, and habitat forming Acropora corals and large-bodied fishes that were once common on the leeward side of the island have become scarce. A proxy for fishing access best predicted the relative change in fish assemblage condition over time, and in turn, declining fish condition was the only factor correlated with declining coral condition, suggesting overfishing may have reduced ecosystem resilience. Additionally, a proxy for watershed pollution predicted modern coral assemblage condition, suggesting pollution is also reducing resilience in densely populated areas. Altogether, it appears that unsustainable fishing reduced ecosystem resilience, as fish composition has shifted to smaller species in lower trophic levels, driven by losses of large predators and herbivores. While prior literature and anecdotal reports indicate that major disturbance events have been rare in Kosrae, small localized disturbances coupled with reduced resilience may have slowly degraded reef condition through time. Improving coral-reef resilience in the face of climate change will therefore require improved understanding and management of growing artisanal fishing pressure and watershed pollution.

Spatial scaling patterns and functional redundancies in a changing boreal lake landscape

USGS Publications Warehouse

Angeler, David G.; Allen, Craig R.; Uden, Daniel R.; Johnson, Richard K.

2015-01-01

Global transformations extend beyond local habitats; therefore, larger-scale approaches are needed to assess community-level responses and resilience to unfolding environmental changes. Using longterm data (1996–2011), we evaluated spatial patterns and functional redundancies in the littoral invertebrate communities of 85 Swedish lakes, with the objective of assessing their potential resilience to environmental change at regional scales (that is, spatial resilience). Multivariate spatial modeling was used to differentiate groups of invertebrate species exhibiting spatial patterns in composition and abundance (that is, deterministic species) from those lacking spatial patterns (that is, stochastic species). We then determined the functional feeding attributes of the deterministic and stochastic invertebrate species, to infer resilience. Between one and three distinct spatial patterns in invertebrate composition and abundance were identified in approximately one-third of the species; the remainder were stochastic. We observed substantial differences in metrics between deterministic and stochastic species. Functional richness and diversity decreased over time in the deterministic group, suggesting a loss of resilience in regional invertebrate communities. However, taxon richness and redundancy increased monotonically in the stochastic group, indicating the capacity of regional invertebrate communities to adapt to change. Our results suggest that a refined picture of spatial resilience emerges if patterns of both the deterministic and stochastic species are accounted for. Spatially extensive monitoring may help increase our mechanistic understanding of community-level responses and resilience to regional environmental change, insights that are critical for developing management and conservation agendas in this current period of rapid environmental transformation.

Nature of Dielectric Properties, Electric Modulus and AC Electrical Conductivity of Nanocrystalline ZnIn2Se4 Thin Films

NASA Astrophysics Data System (ADS)

El-Nahass, M. M.; Attia, A. A.; Ali, H. A. M.; Salem, G. F.; Ismail, M. I.

2018-02-01

The structural characteristics of thermally deposited ZnIn2Se4 thin films were indexed utilizing x-ray diffraction as well as scanning electron microscopy techniques. Dielectric properties, electric modulus and AC electrical conductivity of ZnIn2Se4 thin films were examined in the frequency range from 42 Hz to 106 Hz. The capacitance, conductance and impedance were measured at different temperatures. The dielectric constant and dielectric loss decrease with an increase in frequency. The maximum barrier height was determined from the analysis of the dielectric loss depending on the Giuntini model. The real part of the electric modulus revealed a constant maximum value at higher frequencies and the imaginary part of the electric modulus was characterized by the appearance of dielectric relaxation peaks. The AC electrical conductivity obeyed the Jonscher universal power law. Correlated barrier hopping model was the appropriate mechanism for AC conduction in ZnIn2Se4 thin films. Estimation of the density of states at the Fermi level and activation energy, for AC conduction, was carried out based on the temperature dependence of AC electrical conductivity.

Structure-mechanics property relationship of waste derived biochars.

PubMed

Das, Oisik; Sarmah, Ajit K; Bhattacharyya, Debes

2015-12-15

The widespread applications of biochar in agriculture and environmental remediation made the scientific community ignore its mechanical properties. Hence, to examine the scope of biochar's structural applications, its mechanical properties have been investigated in this paper through nanoindentation technique. Seven waste derived biochars, made under different pyrolysis conditions and from diverse feedstocks, were studied via nanoindentation, infrared spectroscopy, X-ray crystallography, thermogravimetry, and electron microscopy. Following this, an attempt was made to correlate the biochars' hardness/modulus with reaction conditions and their chemical properties. The pine wood biochar made at 900°C and 60min residence time was found to have the highest hardness and elastic modulus of 4.29 and 25.01GPa, respectively. It was shown that a combination of higher heat treatment (≥500°C) temperature and longer residence time (~60min) increases the values of hardness and modulus. It was further realized that pyrolysis temperature was a more dominant factor than residence time in determining the final mechanical properties of biochar particles. The degree of aromaticity and crystallinity of the biochar were also correlated with higher values of hardness and modulus. Copyright © 2015 Elsevier B.V. All rights reserved.

Quantitative sonoelastography for the in vivo assessment of skeletal muscle viscoelasticity

NASA Astrophysics Data System (ADS)

Hoyt, Kenneth; Kneezel, Timothy; Castaneda, Benjamin; Parker, Kevin J.

2008-08-01

A novel quantitative sonoelastography technique for assessing the viscoelastic properties of skeletal muscle tissue was developed. Slowly propagating shear wave interference patterns (termed crawling waves) were generated using a two-source configuration vibrating normal to the surface. Theoretical models predict crawling wave displacement fields, which were validated through phantom studies. In experiments, a viscoelastic model was fit to dispersive shear wave speed sonoelastographic data using nonlinear least-squares techniques to determine frequency-independent shear modulus and viscosity estimates. Shear modulus estimates derived using the viscoelastic model were in agreement with that obtained by mechanical testing on phantom samples. Preliminary sonoelastographic data acquired in healthy human skeletal muscles confirm that high-quality quantitative elasticity data can be acquired in vivo. Studies on relaxed muscle indicate discernible differences in both shear modulus and viscosity estimates between different skeletal muscle groups. Investigations into the dynamic viscoelastic properties of (healthy) human skeletal muscles revealed that voluntarily contracted muscles exhibit considerable increases in both shear modulus and viscosity estimates as compared to the relaxed state. Overall, preliminary results are encouraging and quantitative sonoelastography may prove clinically feasible for in vivo characterization of the dynamic viscoelastic properties of human skeletal muscle.

A Six-Week Resistance Training Program Does Not Change Shear Modulus of the Triceps Brachii.

PubMed

Akagi, Ryota; Shikiba, Tomofumi; Tanaka, Jun; Takahashi, Hideyuki

2016-08-01

We investigated the effect of a 6-week resistance training program on the shear modulus of the triceps brachii (TB). Twenty-three young men were randomly assigned to either the training (n = 13) or control group (n = 10). Before and after conducting the resistance training program, the shear modulus of the long head of the TB was measured at the point 70% along the length of the upper arm from the acromial process of the scapula to the lateral epicondyle of the humerus using shear wave ultrasound elastography. Muscle thickness of the long head of the TB was also determined at the same site by ultrasonography used during both tests. A resistance exercise was performed 3 days a week for 6 weeks using a dumbbell mass-adjusted to 80% of the 1-repetition maximum (1RM). The training effect on the muscle thickness and 1RM was significant. Nevertheless, the muscle shear modulus was not significantly changed after the training program. From the perspective of muscle mechanical properties, the present results indicate that significant adaptation must occur to make the TB more resistant to subsequent damaging bouts during the 6-week training program to target the TB.

Psychosocial Factors Associated with Resilience and Perceived Readiness Among Navy Corpsmen

DTIC Science & Technology

2016-08-15

posttest surveys in large classroom settings at the FMTB–West School. All data for the present study came from the pretest surveys, which were...Stewart.35 Demographics. The pretest survey asked for information on participants’ age, tenure in the Navy, race/ethnicity, education, and paygrade...are not aware of any research examining the correlates of resilience among corpsmen. Thus, one objective of this study was to determine the

Evaluation of 5-HTTLPR Gene Polymorphism and Resilience Components on the Development of Psychopathology in Adolescent Sexual Abuse Cases.

PubMed

Çarkaxhiu Bulut, Gresa; Rodopman Arman, Ayşe; Güney, İlter; Gültepe, Pınar

2017-09-01

More than one-fourth adolescents are exposed to unexpected frightening experiences and traumas until adulthood. In this study, we aimed to determine the potential role of serotonin transporter (5-HTT) gene polymorphism regarding resilience factors in the symptom variability of individuals exposed to sexual abuse. Adolescents aged 11-17 years, who were admitted to the Marmara University Child Psychiatry Outpatient Clinic Forensic division with sexual abuse experience history, were informed about the research, and volunteers were included in the study. Turkish versions of "Kiddie-Schedule for Affective Disorders and Schizophrenia-Present and Lifetime (K-SADS-PL)" was used to assess the psychopathology and functionality. The evaluation of participants also included self-reports based on "Eysenck Personality Inventory" and "Ways of Coping Inventory" for reflecting the resilience domain. The sample included 16 girls (88.9%) and 2 boys (11.1%), and the mean (±standard deviation) age was 14.58±1.97 years. Genotyping of the insertion/deletion polymorphism (5-HTTLPR) in the 5-HTT gene's transcriptional control zone was established, and 8 participants (44.4%) were determined to be of the LL genotype, while 7 (38.8%) were LS and 3 (16.6%) were SS carriers. Considering the relationship between coping styles regarding resilience and genetic variants, 87.5% of participants (n=7) exhibiting problem-focused coping style were determined found to carry the LL allele, while 90% (n=9) who exhibited emotion-focused coping styles were the SS-LS allele carriers (p=0.003). Our findings suggest that 5-HTTLPR gene polymorphism has a significant impact on the formation of coping styles. More studies are needed to determine other factors involved in the complex relationship between 5-HTTLPR gene polymorphism and development of psychopathology.

Community resilience elements and community preparedness at Bukit Antarabangsa

NASA Astrophysics Data System (ADS)

Ridzuan, Ahmad Azan; Kadir, Mohd Juraimy Hj; Yaacob, Safar; Oktari, Rina Suryani; Zainol, Noor Azmi Mohd; Zain, Mazura Mat

2017-07-01

This study was conducted to measure the relationship between community resilience elements (community education, community engagement, community leadership) and community preparedness using questionnaires gathered from 318 samples of the Bukit Antarabangsa community at Ampang Jaya Municipal in Malaysia. The outcomes of SmartPLS path model showed three important findings: firstly, community education significantly correlated with community preparedness. Second, community engagement significantly correlated with community preparedness. Third, community leadership significantly correlated with community preparedness. Statistically, this result confirms that the implementation of community resilience elements such as community education, community engagement, and community leadership act as an important determinant of community preparedness towards disasters in the studied community area sample. In addition, discussion, implications and conclusion are elaborated.

Pathways of Risk and Resilience: Impact of a Family Resilience Program on Active-Duty Military Parents.

PubMed

Saltzman, William R; Lester, Patricia; Milburn, Norweeta; Woodward, Kirsten; Stein, Judith

2016-12-01

Over the past decade, studies into the impact of wartime deployment and related adversities on service members and their families have offered empirical support for systemic models of family functioning and a more nuanced understanding of the mechanisms by which stress and trauma reverberate across family and partner relationships. They have also advanced our understanding of the ways in which families may contribute to the resilience of children and parents contending with the stressors of serial deployments and parental physical and psychological injuries. This study is the latest in a series designed to further clarify the systemic functioning of military families and to explicate the role of resilient family processes in reducing symptoms of distress and poor adaptation among family members. Drawing upon the implementation of the Families Overcoming Under Stress (FOCUS) Family Resilience Program at 14 active-duty military installations across the United States, structural equation modeling was conducted with data from 434 marine and navy active-duty families who participated in the FOCUS program. The goal was to better understand the ways in which parental distress reverberates across military family systems and, through longitudinal path analytic modeling, determine the pathways of program impact on parental distress. The findings indicated significant cross-influence of distress between the military and civilian parents within families, families with more distressed military parents were more likely to sustain participation in the program, and reductions in distress among both military and civilian parents were significantly mediated by improvements in resilient family processes. These results are consistent with family systemic and resilient models that support preventive interventions designed to enhance family resilient processes as an important part of comprehensive services for distressed military families. © 2016 Family Process Institute.

Childhood Bereavement and Lower Stress Resilience in Late Adolescence.

PubMed

Kennedy, Beatrice; Chen, Ruoqing; Valdimarsdóttir, Unnur; Montgomery, Scott; Fang, Fang; Fall, Katja

2018-04-30

Although childhood traumatic experiences are recognized as important determinants for adolescent psychiatric health in general, our objective was to explore the specific influence of childhood bereavement on the stress resilience development trajectory. In this national register-based cohort study, we identified 407,639 men born in Sweden between 1973 and 1983, who underwent compulsory military enlistment examinations in late adolescence, including measures of psychological stress resilience. We defined exposure as loss of a first-degree family member in childhood, and estimated relative risk ratios (RRRs) for reduced (moderate or low), compared with high, stress resilience with 95% confidence intervals (CIs) using multinomial logistic regression. Loss of a parent or sibling in childhood conferred a 49% increased risk of subsequent low stress resilience (RRR, 1.49, 95% CI, 1.41-1.57) and an 8% increased risk of moderate stress resilience (RRR, 1.08, 95% CI, 1.03-1.13) in late adolescence. There was also a graded increase in risk with increasing age at loss; teenagers were at higher risk for low resilience (RRR, 1.64, 95% CI, 1.52-1.77) than children aged 7-12 (RRR, 1.47, 95% CI, 1.34-1.61) and ≤6 years (RRR, 1.16 95% CI, 1.02-1.32). The excess risk was observed for all causes of death, including suicide and unexpected deaths as well as deaths due to other illnesses. The associations remained after exclusion of parents with a history of hospitalization for psychiatric diagnoses. The long-term consequences of childhood bereavement may include lower stress resilience in late adolescence. Copyright © 2018 The Society for Adolescent Health and Medicine. Published by Elsevier Inc. All rights reserved.

Dynamical Resilience Indicators in Time Series of Self-Rated Health Correspond to Frailty Levels in Older Adults.

PubMed

Gijzel, Sanne M W; van de Leemput, Ingrid A; Scheffer, Marten; Roppolo, Mattia; Olde Rikkert, Marcel G M; Melis, René J F

2017-07-01

We currently still lack valid methods to dynamically measure resilience for stressors before the appearance of adverse health outcomes that hamper well-being. Quantifying an older adult's resilience in an early stage would aid complex decision-making in health care. Translating complex dynamical systems theory to humans, we hypothesized that three dynamical indicators of resilience (variance, temporal autocorrelation, and cross-correlation) in time series of self-rated physical, mental, and social health were associated with frailty levels in older adults. We monitored self-rated physical, mental, and social health during 100 days using daily visual analogue scale questions in 22 institutionalized older adults (mean age 84.0, SD: 5.9 years). Frailty was determined by the Survey of Health, Ageing and Retirement in Europe (SHARE) frailty index. The resilience indicators (variance, temporal autocorrelation, and cross-correlation) were calculated using multilevel models. The self-rated health time series of frail elderly exhibited significantly elevated variance in the physical, mental, and social domain, as well as significantly stronger cross-correlations between all three domains, as compared to the nonfrail group (all P < 0.001). Temporal autocorrelation was not significantly associated with frailty. We found supporting evidence for two out of three hypothesized resilience indicators to be related to frailty levels in older adults. By mirroring the dynamical resilience indicators to a frailty index, we delivered a first empirical base to validate and quantify the construct of systemic resilience in older adults in a dynamic way. © The Author 2017. 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.

Improving adolescent mental health and resilience through a resilience-based intervention in schools: study protocol for a randomised controlled trial.

PubMed

Dray, Julia; Bowman, Jenny; Freund, Megan; Campbell, Elizabeth; Wolfenden, Luke; Hodder, Rebecca K; Wiggers, John

2014-07-18

Research investigating the effectiveness of universal interventions to reduce the risk of mental health problems remains limited. Schools are a promising setting within which adolescents can receive interventions aimed at promoting their mental health. The aim of this study is to assess the effectiveness of a resilience-based prevention-focused intervention in reducing the risk of mental health problems among adolescents attending secondary school in socio-economically disadvantaged areas. A cluster randomised control trial will be conducted, with schools as the unit of randomisation. Initially, 32 secondary schools will be randomly allocated to a control or intervention group (12 control and 20 intervention). An intervention focused on improving student internal and external resilience factors will be implemented in intervention schools. A survey of students in Grade 7 in both intervention and control schools will be conducted (baseline) and repeated three years later when the students are in Grade 10. The Strengths and Difficulties Questionnaire will be used to measure the risk of mental health problems. At follow-up, the risk of mental health problems will be compared between Grade 10 students in intervention and control schools to determine intervention effectiveness. The study presents an opportunity to determine the effectiveness of a comprehensive resilience-based intervention in reducing the risk of mental health problems in adolescents attending secondary schools. The outcomes of the trial are of importance to youth, schools, mental health clinicians and policymakers. Australian New Zealand Clinical Trials Registry, ACTRN12611000606987, registered 14 June 2011.

Keystone characteristics that support cultural resilience in Karen refugee parents

NASA Astrophysics Data System (ADS)

Harper, Susan G.

2016-12-01

This participatory action research study used the conceptual framework of social-ecological resilience to explore how Karen (pronounced Ka·rén) refugee parents re-construct cultural resilience in resettlement. The funds of knowledge approach helped to define essential knowledge used by Karen parents within their own community. Framing this study around the concept of resilience situated it within an emancipatory paradigm: refugee parents were actors choosing their own cultural identity and making decisions about what cultural knowledge was important for the science education of their children. Sustainability science with its capacity to absorb indigenous knowledge as legitimate scientific knowledge offered a critical platform for reconciling Karen knowledge with scientific knowledge for science education. Photovoice, participant observation, and semi-structured interviews were used to create visual and written narrative portraits of Karen parents. Narrative analysis revealed that Karen parents had constructed a counter-narrative in Burma and Thailand that enabled them to resist assimilation into the dominant ethnic culture; by contrast, their narrative of life in resettlement in the U.S. focused on the potential for self-determination. Keystone characteristics that contributed to cultural resilience were identified to be the community garden and education as a gateway to a transformed future. Anchored in a cultural tradition of farming, these Karen parents gained perspective and comfort in continuity and the potential of self-determination rooted in the land. Therefore, a cross-cultural learning community for Karen elementary school students that incorporates the Karen language and Karen self-sustaining knowledge of horticulture would be an appropriate venue for building a climate of reciprocity for science learning.

Improving adolescent mental health and resilience through a resilience-based intervention in schools: study protocol for a randomised controlled trial

PubMed Central

2014-01-01

Background Research investigating the effectiveness of universal interventions to reduce the risk of mental health problems remains limited. Schools are a promising setting within which adolescents can receive interventions aimed at promoting their mental health. The aim of this study is to assess the effectiveness of a resilience-based prevention-focused intervention in reducing the risk of mental health problems among adolescents attending secondary school in socio-economically disadvantaged areas. Methods/design A cluster randomised control trial will be conducted, with schools as the unit of randomisation. Initially, 32 secondary schools will be randomly allocated to a control or intervention group (12 control and 20 intervention). An intervention focused on improving student internal and external resilience factors will be implemented in intervention schools. A survey of students in Grade 7 in both intervention and control schools will be conducted (baseline) and repeated three years later when the students are in Grade 10. The Strengths and Difficulties Questionnaire will be used to measure the risk of mental health problems. At follow-up, the risk of mental health problems will be compared between Grade 10 students in intervention and control schools to determine intervention effectiveness. Discussion The study presents an opportunity to determine the effectiveness of a comprehensive resilience-based intervention in reducing the risk of mental health problems in adolescents attending secondary schools. The outcomes of the trial are of importance to youth, schools, mental health clinicians and policymakers. Trial registration Australian New Zealand Clinical Trials Registry, ACTRN12611000606987, registered 14 June 2011. PMID:25037455

Zn-doped etch-and-rinse model dentin adhesives: Dentin bond integrity, biocompatibility, and properties.

PubMed

Barcellos, Daphne Câmara; Fonseca, Beatriz Maria; Pucci, César Rogério; Cavalcanti, Bruno das Neves; Persici, Erasmo De Souza; Gonçalves, Sérgio Eduardo de Paiva

2016-07-01

This study assessed a 6 month resin/dentin bond's durability and cytotoxic effect of Zn-doped model dentin adhesives. The mechanical and physicochemical properties were also tested. A model etch-and-rinse single-bottle adhesive was formulated (55wt.% Bis-GMA, 45wt.% HEMA, 0.5wt.% CQ, 0.5wt.% DMAEMA) and Zinc methacrylate (Zn-Mt) or ZnO nanoparticles (ZnOn) were added to the model's adhesive, resulting in three groups: Group Control (control model adhesive); Group Zn-Mt (1wt.% Zn-Mt incorporated to adhesive) and Group ZnOn (1wt.% ZnOn incorporated to adhesive). The microtensile bond strength (mTBS) was assessed after 24h or 6 months in water storage. Mechanical properties (diametral tensile strength/DTS, flexural strength/FS, flexural modulus/FM, resilience modulus/RM, and compressive strength/CS) and physicochemical properties (polymerization shrinkage/PS, contact angle/CA, water sorption/WS, and water solubility/WS) were also tested. Cytotoxicity was evaluated with SRB biochemical assay. No significant difference in the DTS, FS, FM, CS, CA, WS, and WS were found when 1% of ZnOn or Zn-Mt was added to the model dentin adhesive. Group Zn-Mt decreased the RM of adhesive. Groups Zn-Mt and ZnOn decreased the PS of adhesives. Group ZnOn reduced the cytotoxicity of adhesive. Group ZnOn preserved mTBS after 6 months storage without degradation areas as seen by SEM analysis. The 1wt.% ZnOn may preserve the integrity of the hybrid layer and may reduce cytotoxicity and polymerization shrinkage of model dentin adhesive. The addition of Zn-Mt to the adhesive had no beneficial effects. Copyright © 2016 The Academy of Dental Materials. All rights reserved.

Bone Density and Cortical Structure after Pediatric Renal Transplantation

PubMed Central

Terpstra, Anniek M.; Kalkwarf, Heidi J.; Shults, Justine; Zemel, Babette S.; Wetzsteon, Rachel J.; Foster, Bethany J.; Strife, C. Frederic; Foerster, Debbie L.

2012-01-01

The impact of renal transplantation on trabecular and cortical bone mineral density (BMD) and cortical structure is unknown. We obtained quantitative computed tomography scans of the tibia in pediatric renal transplant recipients at transplantation and 3, 6, and 12 months; 58 recipients completed at least two visits. We used more than 700 reference participants to generate Z-scores for trabecular BMD, cortical BMD, section modulus (a summary measure of cortical dimensions and strength), and muscle and fat area. At baseline, compared with reference participants, renal transplant recipients had significantly lower mean section modulus and muscle area; trabecular BMD was significantly greater than reference participants only in transplant recipients younger than 13 years. After transplantation, trabecular BMD decreased significantly in association with greater glucocorticoid exposure. Cortical BMD increased significantly in association with greater glucocorticoid exposure and greater decreases in parathyroid hormone levels. Muscle and fat area both increased significantly, but section modulus did not improve. At 12 months, transplantation associated with significantly lower section modulus and greater fat area compared with reference participants. Muscle area and cortical BMD did not differ significantly between transplant recipients and reference participants. Trabecular BMD was no longer significantly elevated in younger recipients and was low in older recipients. Pediatric renal transplant associated with persistent deficits in section modulus, despite recovery of muscle, and low trabecular BMD in older recipients. Future studies should determine the implications of these data on fracture risk and identify strategies to improve bone density and structure. PMID:22282589

Comparison of shear wave velocity measurements assessed with two different ultrasound systems in an ex-vivo tendon strain phantom.

PubMed

Rosskopf, Andrea B; Bachmann, Elias; Snedeker, Jess G; Pfirrmann, Christian W A; Buck, Florian M

2016-11-01

The purpose of this study is to compare the reliability of SW velocity measurements of two different ultrasound systems and their correlation with the tangent traction modulus in a non-static tendon strain model. A bovine tendon was fixed in a custom-made stretching device. Force was applied increasing from 0 up to 18 Newton. During each strain state the tangent traction modulus was determined by the stretcher device, and SW velocity (m/s) measurements using a Siemens S3000 and a Supersonic Aixplorer US machine were done for shear modulus (kPa) calculation. A strong significant positive correlation was found between SW velocity assessed by the two ultrasound systems and the tangent traction modulus (r = 0.827-0.954, p < 0.001), yet all SW velocity-based calculations underestimated the reference tissue tangent modulus. Mean difference of SW velocities with the S3000 was 0.44 ± 0.3 m/s (p = 0.002) and with the Aixplorer 0.25 ± 0.3 m/s (p = 0.034). Mean difference of SW velocity between the two US-systems was 0.37 ± 0.3 m/s (p = 0.012). In conclusion, SW velocities are highly dependent on mechanical forces in the tendon tissue, but for controlled mechanical loads appear to yield reproducible and comparable measurements using different US systems.

Using resistance and resilience concepts to reduce impacts of annual grasses and altered fire regimes on the sagebrush ecosystem and sage-grouse- A strategic multi-scale approach

USGS Publications Warehouse

Chambers, Jeanne C.; Pyke, David A.; Maestas, Jeremy D.; Boyd, Chad S.; Campbell, Steve; Espinosa, Shawn; Havlina, Doug; Mayer, Kenneth F.; Wuenschel, Amarina

2014-01-01

This Report provides a strategic approach for conservation of sagebrush ecosystems and Greater Sage- Grouse (sage-grouse) that focuses specifically on habitat threats caused by invasive annual grasses and altered fire regimes. It uses information on factors that influence (1) sagebrush ecosystem resilience to disturbance and resistance to invasive annual grasses and (2) distribution, relative abundance, and persistence of sage-grouse populations to develop management strategies at both landscape and site scales. A sage-grouse habitat matrix links relative resilience and resistance of sagebrush ecosystems with sage-grouse habitat requirements for landscape cover of sagebrush to help decision makers assess risks and determine appropriate management strategies at landscape scales. Focal areas for management are assessed by overlaying matrix components with sage-grouse Priority Areas for Conservation (PACs), breeding bird densities, and specific habitat threats. Decision tools are discussed for determining the suitability of focal areas for treatment and the most appropriate management treatments.

Linking Resilience of Aquatic Species to Watershed Condition

NASA Astrophysics Data System (ADS)

Flitcroft, R. L.

2017-12-01

Watershed condition means different things to different people. From the perspective of aquatic ecology, watershed condition may be interpreted to mean the capacity of a watershed to support life history diversity of native species. Diversity in expression of life history is thought to confer resilience allowing portions of the broader population to survive stressful conditions. Different species have different life history strategies, many of which were developed through adaptation to regional or local environmental conditions and natural disturbance regimes. By reviewing adaptation strategies for species of interest at regional scales, characteristics of watersheds that confer resilience may be determined. Such assessments must be completed at multiple levels of spatial organization (i.e. sub-watershed, watershed, region) allowing assessments to be inferred across broad spatial extents. In a project on the Wenatchee River watershed, we guided models of wildfire effects on bull trout and spring Chinook from a meta-population perspective to determine risks to survival at local and population scales over multiple extents of spatial organization. In other work in the Oregon Coast Range, we found that historic landslides continue to exert habitat-forming pressure at local scales, leading to patchiness in distribution of habitats for different life stages of coho salmon. Further, climate change work in Oregon estuaries identified different vulnerabilities in terms of juvenile rearing habitat depending on the species of interest and the intensity of future changes in climate. All of these studies point to the importance of considering physical conditions in watersheds at multiple spatial extents from the perspective of native aquatic species in order to understand risks to long-term survival. The broader implications of watershed condition, from this perspective, is the determination of physical attributes that confer resilience to native biota. This may require regionally specific metrics, and across-species synthesis of survival strategies and environmental conditions that confer resilience.

Mechanical characteriztion of single-stranded DNA and single-walled carbon nanotube hybrid structures

NASA Astrophysics Data System (ADS)

Rokadia, Husein Juzer

Hybrid nanostructures of single-stranded DNA (ssDNA) and single-walled carbon nanotubes are being proposed as the basis for the next generation of biosensors. For such biosensors, mechanical properties such as the Young's modulus of the hybrid structures play a critical role, which to the best of the author's knowledge is still unknown. Thus, the determination of the Young's modulus of the ssDNA/swCNT hybrid structures was the primary objective of this study. Hybrid structures of 30mer polyT ssDNA and HiPCORTM swCNTs were conjugated using a well known non-covalent interaction protocol. Atomic force microscopy (AFM) was used to scan and generate topographic images and perform nanoindentation tests on the hybrid structures. Molecular dynamics (MD) simulations using a commercial MD program, Materials StudioRTM were performed to study the nature of non-covalent interactions between the ssDNA and the swCNT on the pico-second timescale. AFM topography scans of the bare control HiPCORTM swCNTs indicated an average diameter of about 1.0 nm and length of 800 nm. Similarly, the control 30mer polyT ssDNA was found to resemble a half-hemispherical domed structure with an average height of 2.1 nm. Nanoindentation tests yielded the transverse Young's modulus of the control swCNTs to be 78.0 GPa. The control ssDNA were found to have a Young's modulus of 3.3 GPa and 4.0 MPa in dry and wet environments, respectively. Topographic scans of the ssDNA/swCNT hybrid structures showed the slender swCNTs fully or partially coated along their lengths by ssDNA. The height of the hybrid structures ranged from 2.5 nm to 7.5 nm. Nanoindentation tests on the ssDNA coated portions of the hybrid structures indicated that, their Young's modulus exponentially decreased with increasing coating thickness. Thinly coated sections were found to have a Young's modulus of 100.0 GPa and 7.0 MPa in dry and wet conditions respectively. The thick walled hybrid sections were found to have an average Young's modulus of 4.5 GPa and 1.0 GPa in the dry and wet environments, respectively. MD results indicated that the wrapping of the ssDNA had a significant impact on the hybrid structures. The longitudinal Young's modulus of a hybrid structure was found to be approximately 50.0 GPa, compared to a bare nanotube whose Young's modulus was approximately 800 GPa. Overall, the experimental and numerical results displayed consistent trends. The experimental results reported the swCNTs to have the highest transverse Young's modulus followed by the hybrids and the ssDNA. Similarly, the numerical simulations predicted the highest longitudinal Young's modulus for the swCNTs, followed by the hybrids and the DNA.

Towards A Theory of Autonomous Reconstitution of Compromised Cyber-Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ramuhalli, Pradeep; Halappanavar, Mahantesh; Coble, Jamie B.

The ability to maintain mission-critical operations in cyber-systems in the face of disruptions is critical. Faults in cyber systems can come from accidental sources (e.g., natural failure of a component) or deliberate sources (e.g., an intelligent adversary). Natural and intentional manipulation of data, computing, or coordination are the most impactful ways that an attacker can prevent an infrastructure from realizing its mission goals. Under these conditions, the ability to reconstitute critical infrastructure becomes important. Specifically, the question is: Given an intelligent adversary, how can cyber systems respond to keep critical infrastructure operational? In cyber systems, the distributed nature of themore » system poses serious difficulties in maintaining operations, in part due to the fact that a centralized command and control apparatus is unlikely to provide a robust framework for resilience. Resilience in cyber-systems, in general, has several components, and requires the ability to anticipate and withstand attacks or faults, as well as recover from faults and evolve the system to improve future resilience. The recovery effort (and any subsequent evolution) may require significant reconfiguration of the system (at all levels – hardware, software, services, permissions, etc.) if the system is to be made resilient to further attack or faults. This is especially important in the case of ongoing attacks, where reconfiguration decisions must be taken with care to avoid further compromising the system while maintaining continuity of operations. Collectively, we will label this recovery and evolution process as “reconstitution”. Currently, reconstitution is performed manually, generally after-the-fact, and usually consists of either standing up redundant systems, check-points (rolling back the configuration to a “clean” state), or re-creating the system using “gold-standard” copies. For enterprise systems, such reconstitution may be performed either directly on hardware, or using virtual machines. A significant challenge within this context is the ability to verify that the reconstitution is performed in a manner that renders the cyber-system resilient to ongoing and future attacks or faults. Fundamentally, the need is to determine optimal configuration of the cyber system when a fault is determined to be present. While existing theories for fault tolerance (for example, Byzantine fault tolerance) can guarantee resilience under certain conditions, in practice, these theories can break down in the face of an intelligent adversary. Further, it is difficult, in a dynamically evolving environment, to determine whether the necessary conditions for resilience have been met, resulting in difficulties in achieving resilient operation. In addition, existing theories do not sufficiently take into account the cost for attack and defense (the adversary is generally assumed to have infinite resources and time), hierarchy of importance (all network resources are assumed to be equally important), and the dynamic nature of some attacks (i.e., as the attack evolves, can resilience be maintained?). Alternative approaches to resilience based on a centralized command and control structure suffer from a single-point-failure. This paper presents preliminary research towards concepts for effective autonomous reconstitution of compromised cyber systems. We describe a mathematical framework as a first step towards a theoretical basis for autonomous reconstitution in dynamic cyber-system environments. We then propose formulating autonomous reconstitution as an optimization problem and describe some of the challenges associated with this formulation. This is followed by a brief discussion on potential solutions to these challenges.« less

Resilience and Function in Adults With Physical Disabilities: An Observational Study.

PubMed

Battalio, Samuel L; Silverman, Arielle M; Ehde, Dawn M; Amtmann, Dagmar; Edwards, Karlyn A; Jensen, Mark P

2017-06-01

To determine if resilience is uniquely associated with functional outcomes (satisfaction with social roles, physical functioning, and quality of life) in individuals with physical disabilities, after controlling for measures of psychological health (depression and anxiety) and symptom severity (pain, fatigue, and sleep disturbance); and to examine the potential moderating effect of sex, age, and diagnosis on the hypothesized associations between resilience and function. Cross-sectional survey study. Surveys were mailed (81% response rate) to a community sample of 1949 individuals with multiple sclerosis, muscular dystrophy, postpoliomyelitis syndrome, or spinal cord injury. Participants were recruited through the Internet or print advertisement (28%), a registry of previous research participants who indicated interest in future studies (21%), a departmental registry of individuals interested in research (19%), disability-specific registries (18%), word of mouth (10%), or other sources (3%). Convenience sample of community-dwelling adults aging with physical disabilities (N=1574), with a mean Connor-Davidson Resilience Scale (10 items) score of 29. Not applicable. Patient-Reported Outcomes Measurement Information System measures of Satisfaction with Social Roles and Activities and Physical Functioning, the World Health Organization's brief Older People's Quality of Life Questionnaire, and the Connor-Davidson Resilience Scale (10 items). After controlling for age, age squared, sex, diagnosis, psychological health, and symptom severity, resilience was significantly and positively associated with satisfaction with social roles (β=.17, P<.001) and quality of life (β=.39, P<.001), but not physical function (β=.04, P>.05). For every 1-point increase in scores of resilience, there was an increase of .50 in the quality of life score and .20 in the satisfaction with social roles score. Sex also moderated the association between resilience and satisfaction with social roles (F 1,1453 =4.09, P=.043). The findings extend past research, providing further evidence indicating that resilience plays a unique role in nonphysical functional outcomes among individuals with physical disabilities. Copyright © 2016 American Congress of Rehabilitation Medicine. All rights reserved.

Obtaining and Mechanical Properties of Ti-Mo-Zr-Ta Alloys

NASA Astrophysics Data System (ADS)

Bălţatu, M. S.; Vizureanu, P.; Geantă, V.; Nejneru, C.; Țugui, C. A.; Focşăneanu, S. C.

2017-06-01

Ti-based alloys are successfully used in the area of orthopedic biomaterials for their enhanced biocompatibility, good corrosion and mechanical properties. The most suitable metals as an alloying element for orthopedic biomaterials are zirconium, molybdenum and tantalum because are non toxic and have good properties. The paper purpose development of two alloys of Ti-Mo-Zr-Ta (TMZT) prepared by arc-melting with several mechanical properties determined by microindentation. The mechanical properties analyzed was Vickers hardness and dynamic elasticity modulus. The investigated alloys presents a low Young’s modulus, an important condition of biomaterials for preventing stress shielding phenomenon.

Determinants of resilience to cigarette smoking among young Australians at risk: an exploratory study.

PubMed

Colgan, Yola; Turnbull, Deborah A; Mikocka-Walus, Antonina A; Delfabbro, Paul

2010-07-08

Numerous researchers studied risk factors associated with smoking uptake, however, few examined protective factors associated with smoking resilience. This study therefore aims to explore determinants of smoking resilience among young people from lower socioeconomic backgrounds who are at risk of smoking. Overall, 92 out of 92 vocational education students accepted invitation to participate in this exploratory study. The Adelaide Technical and Further Education (TAFE) Arts campus was chosen for the study given the focus on studying resilience in young people of lower socioeconomic status i.e. resilient despite the odds. A self-report questionnaire comprising a measure of resilience: sense of coherence, sense of humour, coping styles, depression, anxiety and stress, and family, peers and community support, was distributed among participants aged 15 to 29. Additional factors researched are parental approval and disapproval, course type, and reasons for not smoking. Using the Statistical Package for the Social Sciences (SPSS, version 13.0), analyses were undertaken using frequencies, means, standard deviations, independent sample t-tests, correlations, analysis of variance, logistic regression, and chi-square test. Twenty five (27%) out of 92 students smoked. Young people with peer support tended to smoke (p < .05). A relationship between daily smoking and depression, anxiety and stress was also found (p < .05). When both mothers and fathers disapproved of their children smoking, it had a greater influence on females not smoking, compared with males. The majority of students chose 'health and fitness' as a reason for not smoking. Students in the Dance course tended to not smoke. The current study showed that most students chose 'health and fitness' as the reason for not smoking. Single anti-smoking messages cannot be generalised to all young people, but should recognise that people within different contexts, groups and subcultures will have different reasons for choosing whether or not to smoke. Future studies should use larger samples with a mixed methods design (quantitative and qualitative).

The effect of carbon black filler to the mechanical properties of natural rubber as base isolation system

NASA Astrophysics Data System (ADS)

Ismail, R.; Mahadi, Z. A.; Ishak, I. S.

2018-04-01

This paper presented the study on the effect of carbon black as filler to the mechanical properties of natural rubber for base isolation system. This study used the five formulations with the different amount of carbon black filler for every sample. The samples were tested for tensile, hardness and resilience test. The samples were cured or vulcanized at 1500C for 23 minutes for every formulation. The filler used in this study was the carbon black filler with type N660. The tensile test was done to determine the ability of the sample in term of the elongation with the load at break. The hardness test, it has been done to determine the ability of the sample to resist the load. This hardness was measured in the unit of IRHD. The resilience test was being done to determine the properties of the sample in term of rebound characteristics. The finding of this study showed that, the high the loading of carbon black filler, the high the tensile strength of the sample and the high the hardness of the sample. In term of resilience, it was inversely proportional to the loading of the carbon black filler.

Determining elastic moduli of materials in pavement systems by surface deflection data : a feasibility study.

DOT National Transportation Integrated Search

1975-01-01

The determination of the elastic, or Young's, modulus, E, of the materials in each layer in an n-layered pavement system given the number, order, thicknesses, and Poisson's ratios of the layers, and the surface load and deflection data, is not possib...

Determining modulus of elasticity of ancient structural timber

Treesearch

Houjiang Zhang; Lei Zhu; Yanliang Sun; Xiping Wang; Haicheng Yan

2011-01-01

During maintenance of ancient timber architectures, it is important to determine mechanical properties of the wood component materials non-destructively and effectively, so that degraded members may be replaced or repaired to avoid structural failure. Experimental materials are four larch (Larix principis-rupprechtii Mayr.) components, which were taken down from the...

Energy Harvesting and Storage Systems for Future AF Vehicles

DTIC Science & Technology

2012-05-18

mechanical testing setup/procedures to determine the Young’s modulus and fracture strength of solar energy harvesting modules. Figure D1 SEM micrograph of...failure modes. (4 configurations; 2 repetitions) Table D3. Summary of mechanical testing activity The goal of the test is to determine the fracture ...

Disease epidemics: Lessons for resilience in an increasingly connected world

USGS Publications Warehouse

Allen, Craig R.; DeWitte, S.N.; Kurth, M.H.; Linkov, I.

2016-01-01

In public health, the term resilience often refers to the personality traits that individuals possess which help them endure and recover from stressors. However, resilience as a system characteristic, especially in regards to complex social-ecological systems, can be informative for public health at scales larger than the individual. Acute shocks to systems occur against a background of existing conditions, which are crucial determinants of the eventual public health outcomes of those shocks, and in the context of complex dependencies among and between ecological and societal elements. Many components of a system's baseline condition are chronic public health concerns themselves and diminish the capacity of the system to perform in the face of acute shocks. The emerging field of resilience management is concerned with holistically assessing and improving a system's ability to prepare for and absorb disruption, and then recover and adapt across physical, information, environmental and social domains. Integrating resilience considerations into current risk- and evidence-based approaches to disease control and prevention1 can move public health efforts toward more proactive and comprehensive solutions for protecting and improving the health of communities. Here, we look to the case of the Black Death as an illustrative case of a dramatic transformation in human history, an acute shock to a system that was underlain by chronic social maladies, to derive lessons about resilience management for public health in contemporary systems.

Novel Indicators for the Quantification of Resilience in Critical Material Supply Chains, with a 2010 Rare Earth Crisis Case Study

PubMed Central

2017-01-01

We introduce several new resilience metrics for quantifying the resilience of critical material supply chains to disruptions and validate these metrics using the 2010 rare earth element (REE) crisis as a case study. Our method is a novel application of Event Sequence Analysis, supplemented with interviews of actors across the entire supply chain. We discuss resilience mechanisms in quantitative terms–time lags, response speeds, and maximum magnitudes–and in light of cultural differences between Japanese and European corporate practice. This quantification is crucial if resilience is ever to be taken into account in criticality assessments and a step toward determining supply and demand elasticities in the REE supply chain. We find that the REE system showed resilience mainly through substitution and increased non-Chinese primary production, with a distinct role for stockpiling. Overall, annual substitution rates reached 10% of total demand. Non-Chinese primary production ramped up at a speed of 4% of total market volume per year. The compound effect of these mechanisms was that recovery from the 2010 disruption took two years. The supply disruption did not nudge a system toward an appreciable degree of recycling. This finding has important implications for the circular economy concept, indicating that quite a long period of sustained material constraints will be necessary for a production-consumption system to naturally evolve toward a circular configuration. PMID:28257181

Latent classes of resilience and psychological response among only-child loss parents in China.

PubMed

Wang, An-Ni; Zhang, Wen; Zhang, Jing-Ping; Huang, Fei-Fei; Ye, Man; Yao, Shu-Yu; Luo, Yuan-Hui; Li, Zhi-Hua; Zhang, Jie; Su, Pan

2017-10-01

Only-child loss parents in China recently gained extensive attention as a newly defined social group. Resilience could be a probable solution out of the psychological dilemma. Using a sample of 185 only-child loss people, this study employed latent class analysis (a) to explore whether different classes of resilience could be identified, (b) to determine socio-demographic characteristics of each class, and (c) to compare the depression and the subjective well-being of each class. The results supported a three-class solution, defined as 'high tenacity-strength but moderate optimism class', 'moderate resilience but low self-efficacy class' and 'low tenacity but moderate adaption-dependence class'. Parents with low income and medical insurance of low reimbursement type and without endowment insurance occupied more proportions in the latter two classes. The latter two classes also had a significant higher depression scores and lower subjective well-being scores than high tenacity-strength but moderate optimism class. Future work should care those socio-economically vulnerable bereaved parents, and an elastic economic assistance policy was needed. To develop targeted resilience interventions, the emphasis of high tenacity-strength but moderate optimism class should be the optimism. Moderate resilience but low self-efficacy class should be self-efficacy, and low tenacity but moderate adaption-dependence class should be tenacity. Copyright © 2016 John Wiley & Sons, Ltd.

Lack of Resilience Is Related to Stress-Related Sleep Reactivity, Hyperarousal, and Emotion Dysregulation in Insomnia Disorder

PubMed Central

Palagini, Laura; Moretto, Umberto; Novi, Martina; Masci, Isabella; Caruso, Danila; Drake, Christopher L.; Riemann, Dieter

2018-01-01

Study Objectives: According to the diathesis-stress model of insomnia, insomnia may develop in vulnerable individuals in response to stress. Resilience is a psychobiological factor that determines an individual's capacity to adapt successfully to stressful events and low resilience increases vulnerability for development of mental disorders. The aim was to explore resilience in subjects with insomnia and its relationship with the factors that contribute to its development and perpetuation. Methods: The study consisted of 58 subjects with Insomnia Disorder according to the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition and 38 good sleepers. Resilience Scale for Adults (RSA), Ford Insomnia Response to Stress Test (FIRST), Pre-sleep Arousal Scale (PSAS), and Difficulties in Emotion Regulation Scale (DERS) were administered while taking into account psychiatric symptoms. Differences in means between groups were assessed using t test or Mann-Whitney U/Wilcoxon test. Linear/multivariable regression analyses and mediation analyses were performed. Results: Subjects with insomnia (24 females, mean age 49 ± 2.1 years) had lower RSA and higher FIRST, DERS, and PSAS scores than good sleepers (22 females, mean age 47.2 ± 1.2 years). After controlling for anxiety/depressive symptoms, low resilience correlated with high stress-related sleep reactivity (P = .004), pre-sleep cognitive hyperarousal (P = .01) and emotion dysregulation (P = .01). Emotion dysregulation mediated the relationship between low resilience and cognitive hyperarousal (Z = 2.06, P = .03). Conclusions: Subjects with insomnia showed low resilience, which was related to high stress-related sleep reactivity, emotional dysregulation, and hyperarousal. If resilience helps to minimize the extent of pathogenesis in the developmental process, an early identification of vulnerable candidates should be useful for preventing insomnia development and maintenance. Commentary: A commentary on this article appears in this issue on page 709. Citation: Palagini L, Moretto U, Novi M, Masci I, Caruso D, Drake CL, Riemann D. Lack of resilience is related to stress-related sleep reactivity, hyperarousal, and emotion dysregulation in insomnia disorder. J Clin Sleep Med. 2018;14(5):759–766. PMID:29734989

Stress From Uncertainty and Resilience Among Depressed and Burned Out Residents: A Cross-Sectional Study.

PubMed

Simpkin, Arabella L; Khan, Alisa; West, Daniel C; Garcia, Briana M; Sectish, Theodore C; Spector, Nancy D; Landrigan, Christopher P

2018-03-07

Depression and burnout are highly prevalent among residents, but little is known about modifiable personality variables, such as resilience and stress from uncertainty, that may predispose to these conditions. Residents are routinely faced with uncertainty when making medical decisions. To determine how stress from uncertainty is related to resilience among pediatric residents and whether these attributes are associated with depression and burnout. We surveyed 86 residents in pediatric residency programs from 4 urban freestanding children's hospitals in North America in 2015. Stress from uncertainty was measured with the use of the Physicians' Reaction to Uncertainty Scale, resilience with the use of the 14-item Resilience Scale, depression with the use of the Harvard National Depression Screening Scale; and burnout with the use of single-item measures of emotional exhaustion and depersonalization from the Maslach Burnout Inventory. Fifty out of 86 residents responded to the survey (58.1%). Higher levels of stress from uncertainty correlated with lower resilience (r = -0.60; P < .001). Five residents (10%) met depression criteria and 15 residents (31%) met burnout criteria. Depressed residents had higher mean levels of stress due to uncertainty (51.6 ± 9.1 vs 38.7 ± 6.7; P < .001) and lower mean levels of resilience (56.6 ± 10.7 vs 85.4 ± 8.0; P < .001) compared with residents who were not depressed. Burned out residents also had higher mean levels of stress due to uncertainty (44.0 ± 8.5 vs 38.3 ± 7.1; P = .02) and lower mean levels of resilience (76.7 ± 14.8 vs 85.0 ± 9.77; P = .02) compared with residents who were not burned out. We found high levels of stress from uncertainty, and low levels of resilience were strongly correlated with depression and burnout. Efforts to enhance tolerance of uncertainty and resilience among residents may provide opportunities to mitigate resident depression and burnout. Copyright © 2018 Academic Pediatric Association. Published by Elsevier Inc. All rights reserved.

Predicting changes in quality of life and emotional distress in Chinese patients with lung, gastric, and colon-rectal cancer diagnoses: the role of psychological resilience.

PubMed

Ye, Zeng Jie; Qiu, Hong Zhong; Li, Peng Fei; Liang, Mu Zi; Zhu, Yun Fei; Zeng, Zhen; Hu, Guang Yun; Wang, Shu Ni; Quan, Xiao Ming

2017-06-01

Patients with cancer often experience considerable emotional distress, which decreases their quality of life (QOL). Resilience is defined as the psychological characteristics that promote positive adaptation in the face of stress and adversity; however, the relationships among QOL, resilience, and emotional distress in patients with cancer, especially Chinese patients with cancer, are under-researched in the literature. Quality of Life Questionnaire Core 30 items, Zung Self-Rating Anxiety Scale, and the Zung Self-Rating Depression Scale were applied in this study. Univariate correlated analysis and multivariate logistic regression analysis were used to test the associations among resilience, emotional distress, and QOL with a sample of 276 participants. A Sobel test was conducted to determine whether the indirect effect of resilience was significant. The mean ratings of QOL (59.2), resilience (20.8), anxiety (43.1), and depression (47.7) were reported. The correlations between resilience and QOL in patients with lung cancer were significantly increased compared with patients with gastric or colorectal cancer (Spearman coefficient squares of 0.284, 0.189, and 0.227, respectively). The highest quartile of the resilience level was associated with a 64% (odds ratio = 0.36, 95% confidence interval = 0.17-0.75, P = .006), 70% (odds ratio = 0.30, 95% confidence interval = 0.14-0.63), and 90% (odds ratio = 0.10, 95% confidence interval = 0.04-0.26, P < .001) reduction in the risk of emotional distress compared with the lowest quartile. The Sobel test indicated a buffering effect of resilience that was significant for depression (Sobel value = 2.002, P = .045) but not anxiety (Sobel value = 1.336, P = .182). The present study suggests that psychological resilience is positively associated with QOL and may comprise a robust buffer between depression and QOL in Chinese patients with cancer. Copyright © 2016 John Wiley & Sons, Ltd.

Resistance to invasion and resilience to fire in desert shrublands of North America

USGS Publications Warehouse

Brooks, Matthew L.; Chambers, Jeanne C.

2011-01-01

Settlement by Anglo-Americans in the desert shrublands of North America resulted in the introduction and subsequent invasion of multiple nonnative grass species. These invasions have altered presettlement fire regimes, resulted in conversion of native perennial shrublands to nonnative annual grasslands, and placed many native desert species at risk. Effective management of these ecosystems requires an understanding of their ecological resistance to invasion and resilience to fire. Resistance and resilience differ among the cold and hot desert shrublands of the Great Basin, Mojave, Sonoran, and Chihuahuan deserts in North America. These differences are largely determined by spatial and temporal patterns of productivity but also are affected by ecological memory, severity and frequency of disturbance, and feedbacks among invasive species and disturbance regimes. Strategies for preventing or managing invasive plant/fire regimes cycles in desert shrublands include: 1) conducting periodic resource assessments to evaluate the probability of establishment of an altered fire regime; 2) developing an understanding of ecological thresholds associate within invasion resistance and fire resilience that characterize transitions from desirable to undesirable fire regimes; and 3) prioritizing management activities based on resistance of areas to invasion and resilience to fire.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ibarraran , Maria E.; Malone, Elizabeth L.; Brenkert, Antoinette L.

Climate change alters different localities on the planet in different ways. The impact on each region depends mainly on the degree of vulnerability that natural ecosystems and human-made infrastructure have to changes in climate and extreme meteorological events, as well as on the coping and adaptation capacity towards new environmental conditions. This study assesses the current resilience of Mexico and Mexican states to such changes, as well as how this resilience will look in the future. In recent studies (Moss et al. 2000, Brenkert and Malone 2005, Malone and Brenket 2008, Ibarrarán et al. 2007), the Vulnerability-Resilience Indicators Model (VRIM)more » is used to integrate a set of proxy variables that determine the resilience of a region to climate change. Resilience, or the ability of a region to respond to climate variations and natural events that result from climate change, is given by its adaptation and coping capacity and its sensitivity. On the one hand, the sensitivity of a region to climate change is assessed, emphasizing its infrastructure, food security, water resources, and the health of the population and regional ecosystems. On the other hand, coping and adaptation capacity is based on the availability of human resources, economic capacity and environmental capacity.« less

An Architecture, System Engineering, and Acquisition Approach for Space System Software Resiliency

NASA Astrophysics Data System (ADS)

Phillips, Dewanne Marie

Software intensive space systems can harbor defects and vulnerabilities that may enable external adversaries or malicious insiders to disrupt or disable system functions, risking mission compromise or loss. Mitigating this risk demands a sustained focus on the security and resiliency of the system architecture including software, hardware, and other components. Robust software engineering practices contribute to the foundation of a resilient system so that the system "can take a hit to a critical component and recover in a known, bounded, and generally acceptable period of time". Software resiliency must be a priority and addressed early in the life cycle development to contribute a secure and dependable space system. Those who develop, implement, and operate software intensive space systems must determine the factors and systems engineering practices to address when investing in software resiliency. This dissertation offers methodical approaches for improving space system resiliency through software architecture design, system engineering, increased software security, thereby reducing the risk of latent software defects and vulnerabilities. By providing greater attention to the early life cycle phases of development, we can alter the engineering process to help detect, eliminate, and avoid vulnerabilities before space systems are delivered. To achieve this objective, this dissertation will identify knowledge, techniques, and tools that engineers and managers can utilize to help them recognize how vulnerabilities are produced and discovered so that they can learn to circumvent them in future efforts. We conducted a systematic review of existing architectural practices, standards, security and coding practices, various threats, defects, and vulnerabilities that impact space systems from hundreds of relevant publications and interviews of subject matter experts. We expanded on the system-level body of knowledge for resiliency and identified a new software architecture framework and acquisition methodology to improve the resiliency of space systems from a software perspective with an emphasis on the early phases of the systems engineering life cycle. This methodology involves seven steps: 1) Define technical resiliency requirements, 1a) Identify standards/policy for software resiliency, 2) Develop a request for proposal (RFP)/statement of work (SOW) for resilient space systems software, 3) Define software resiliency goals for space systems, 4) Establish software resiliency quality attributes, 5) Perform architectural tradeoffs and identify risks, 6) Conduct architecture assessments as part of the procurement process, and 7) Ascertain space system software architecture resiliency metrics. Data illustrates that software vulnerabilities can lead to opportunities for malicious cyber activities, which could degrade the space mission capability for the user community. Reducing the number of vulnerabilities by improving architecture and software system engineering practices can contribute to making space systems more resilient. Since cyber-attacks are enabled by shortfalls in software, robust software engineering practices and an architectural design are foundational to resiliency, which is a quality that allows the system to "take a hit to a critical component and recover in a known, bounded, and generally acceptable period of time". To achieve software resiliency for space systems, acquirers and suppliers must identify relevant factors and systems engineering practices to apply across the lifecycle, in software requirements analysis, architecture development, design, implementation, verification and validation, and maintenance phases.

Bullying and Social Anxiety in Chinese Children: Moderating Roles of Trait Resilience and Psychological Suzhi.

PubMed

Wu, Lili; Zhang, Dajun; Cheng, Gang; Hu, Tianqiang

2018-02-01

Research examining the relationship between bullying victimization and social anxiety has mainly been conducted in Western countries, and little is known about the mechanisms underlying this relationship. This study explores the correlation between bullying victimization and social anxiety in a Chinese context and determines the moderating roles of psychological suzhi (a mental quality characterized by being steady, essential and implicit that affects adaptive, developmental, and creative behavior) and trait resilience among victims of bullying. Data were obtained from a stratified sample of 1903 children in the fourth, fifth, and sixth grades. All participants completed measures of bullying victimization, social anxiety, trait resilience, and psychological suzhi. The results indicated that, after controlling for grade, residential area, and parental marital status, bullying victimization positively predicted children's social anxiety. In addition, multi-group analysis suggested that the association in girls was stronger relative to that observed in boys. Regarding underlying processes, trait resilience moderated the effect of bullying victimization on social anxiety only in girls. Further assessment of the latent interaction effects indicated that the protective effect of trait resilience was stronger for girls experiencing high, relative to low, levels of bullying victimization, and psychological suzhi buffered against the detrimental effects of bullying on children's social anxiety. Most notably, unlike the moderating effect of resilience, the buffering effect of psychological suzhi against social anxiety was most prominent when bullying victimization was low. Findings underscore the importance of enhancing trait resilience and psychological suzhi in interventions designed to reduce children's social anxiety. Copyright © 2017 Elsevier Ltd. All rights reserved.

Childhood Trauma and COMT Genotype Interact to Increase Hippocampal Activation in Resilient Individuals.

PubMed

van Rooij, Sanne J H; Stevens, Jennifer S; Ely, Timothy D; Fani, Negar; Smith, Alicia K; Kerley, Kimberly A; Lori, Adriana; Ressler, Kerry J; Jovanovic, Tanja

2016-01-01

Both childhood trauma and a functional catechol-O-methyltransferase (COMT) genetic polymorphism have been associated with posttraumatic stress disorder (PTSD) and depression; however, it is still unclear whether the two interact and how this interaction relates to long-term risk or resilience. Imaging and genotype data were collected on 73 highly traumatized women. DNA extracted from saliva was used to determine COMT genotype (Val/Val, n = 38, Met carriers, n = 35). Functional MRI data were collected during a Go/NoGo task to investigate the neurocircuitry underlying response inhibition. Self-report measures of adult and childhood trauma exposure, PTSD and depression symptom severity, and resilience were collected. Childhood trauma was found to interact with COMT genotype to impact inhibition-related hippocampal activation. In Met carriers, more childhood trauma was associated with decreased hippocampal activation, whereas in the Val/Val group childhood trauma was related to increased hippocampal activation. Second, hippocampal activation correlated negatively with PTSD and depression symptoms and positively with trait resilience. Moreover, hippocampal activation mediated the relationship between childhood trauma and psychiatric risk or resilience in the Val/Val, but not in the Met carrier group. These data reveal a potential mechanism by which childhood trauma and COMT genotype interact to increase risk for trauma-related psychopathology or resilience. Hippocampal recruitment during inhibition may improve the ability to use contextual information to guide behavior, thereby enhancing resilience in trauma-exposed individuals. This finding may contribute to early identification of individuals at risk and suggests a mechanism that can be targeted in future studies aiming to prevent or limit negative outcomes.

What childhood characteristics predict psychological resilience to economic shocks in adulthood?

PubMed Central

Powdthavee, Nattavudh

2015-01-01

This paper investigates whether people’s psychological resilience to one of the most important economic shocks – job loss – can be predicted using early childhood characteristics. Using a longitudinal data that tracked almost 3000 children into adulthood, we showed that the negative effect of unemployment on mental well-being and life satisfaction is significantly larger for workers who, as adolescents, had a relatively poor father-child relationship. Maternal unemployment, on the other hand, is a good predictor of how individuals react psychologically to future unemployment. Although the results should be viewed as illustrative and more research is needed, the current article provides new longitudinal evidence that psychological resilience to job loss may be determined early on in the life cycle. PMID:26997688

Stressful life events and resilience among carers of Aboriginal children in urban New South Wales: cross-sectional findings from the Study of Environment on Aboriginal Resilience and Child Health (SEARCH).

PubMed

Young, Christian; Craig, Jonathan C; Clapham, Kathleen; Williams, Sandra; Williamson, Anna

2018-06-06

In caregivers of urban Aboriginal children, to determine the frequency of major stressful life events, the proportion who meet criteria for resilience, and factors that are associated with resilience. Cross-sectional survey. Four Aboriginal Community Controlled Health Services located in urban or regional areas in New South Wales, Australia. 574 caregivers of Aboriginal children participating in the Study of Environment on Aboriginal Resilience and Child Health. Resilience, defined as having experienced three or more stressful life events in the last 12 months, and having scores of ≤21 on the Kessler 10 Psychological Distress scale. Over half (315, 55%) of the caregivers reported three or more stressful life events-the most common being a close family member who was hospitalised with a serious medical problem (259, 45%). Of the participants who experienced three or more stressful life events, almost three-quarters (227, 72%) met the criteria for resilience. Using multivariable analysis, two factors were independently associated with resilience: not having a physical health problem that limited normal activities (adjusted OR (aOR) 4.3; 95% CI 2.0 to 9.0), and not having problems caused by alcohol within the home (aOR 5.3; 95% CI 2.2 to 12.8). Having a child whose behaviour placed a great deal of burden on the family was associated with less resilience (aOR 0.25; 95% CI 0.09 to 0.68). Caregivers of urban Aboriginal children experienced a large number of stressful events, the most common being the poor health of close family members, but most exhibited resilience. Resilience was associated with stable family environments and good physical health. The high number of stressful life events that caregivers experience is reflective of broader inequalities that Aboriginal communities face. The availability of easily accessible and long-term health and support services may go some way to reducing this inequality and improving social and emotional well-being for Aboriginal families. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Environmental Assessment for Sustainability and Resiliency for Ecological and Human Health

PubMed Central

Burger, Joanna; Gochfeld, Michael; Clarke, James; Jeitner, Christian; Pittfield, Taryn

2015-01-01

Considerable attention has been devoted to environmental assessment and monitoring, primarily by physical and biological scientists, and more recently by social scientists. However, population growth and global change have resulted in an imperative to assess the resiliency of the environment to adapt to large scale changes and to continue to produce goods and services for future generations (sustainability). Changing land use needs or expectations may require the remediation and restoration of degraded or contaminated land. This paper provides an overview of monitoring types, and discusses how indicators for the different monitoring types can be developed to address questions of ecological health, human health, and whether restoration and remediation are effective. We suggest that along with more traditional types of monitoring, agencies should consider recovery indicators or metrics, as well as resiliency metrics. We suggest that one goal of assessment should be to determine if management, remediation, restoration, and mitigation reduce recovery time, thus reducing community vulnerability and enhancing resiliency to environmental stressors and disasters. PMID:27468428

Transparent Conductors from Carbon Nanotubes LBL-Assembled with Polymer Dopant with π-π Electron Transfer

PubMed Central

Zhu, Jian; Shim, Bong Sup; Di Prima, Matthew; Kotov, Nicholas A.

2011-01-01

Single-walled carbon nanotube (SWNT) and other carbon-based coatings are being considered as replacements for indium tin oxide (ITO). The problems of transparent conductors (TCs) coatings from SWNT and similar materials include poor mechanical properties, high roughness, low temperature resilience, and fast loss of conductivity. The simultaneous realization of these desirable characteristics can be achieved using high structural control of layer-by-layer (LBL) deposition, which is demonstrated by the assembly of hydroethyl cellulose (HOCS) and sulfonated polyetheretherketone (SPEEK)-SWNTs. A new type of SWNT doping based on electron transfer from valence bands of nanotubes to unoccupied levels of SPEEK through π-π interactions was identified for this system. It leads to a conductivity of 1.1×105 S/m at 66wt% loadings of SWNT. This is better than other polymer/SWNT composites and translates into surface conductivity of 920 ohms/sq and transmittance of 86.7% at 550nm. The prepared LBL films also revealed unusually high temperature resilience up to 500°C, and low roughness of 3.5 nm (ITO glass - 2.4 nm). Tensile modulus, ultimate strength, and toughness of such coatings are 13±2 GPa, 366±35 MPa and 8±3 kJ/m3, respectively, and exceed corresponding parameters of all similar TCs. The cumulative figure of merit, ΠTC, which included the critical failure strain relevant for flexible electronics, was ΠTC = 0.022 and should be compared to ΠTC = 0.006 for commercial ITO. Further optimization is possible using stratified nanoscale coatings and improved doping from the macromolecular LBL components. PMID:21524068

Determination of the η‧-nucleus optical potential

NASA Astrophysics Data System (ADS)

Nanova, M.; Metag, V.; Paryev, E. Ya.; Bayadilov, D.; Bantes, B.; Beck, R.; Beloglazov, Y. A.; Böse, S.; Brinkmann, K.-T.; Challand, Th.; Crede, V.; Dahlke, T.; Dietz, F.; Drexler, P.; Eberhardt, H.; Elsner, D.; Ewald, R.; Fornet-Ponse, K.; Friedrich, S.; Frommberger, F.; Funke, Ch.; Gottschall, M.; Gridnev, A.; Grüner, M.; Gutz, E.; Hammann, Ch.; Hammann, D.; Hannappel, J.; Hartmann, J.; Hillert, W.; Hoffmeister, P.; Honisch, Ch.; Jaegle, I.; Kaiser, D.; Kalinowsky, H.; Kammer, S.; Keshelashvili, I.; Kleber, V.; Klein, F.; Klempt, E.; Krusche, B.; Lang, M.; Lopatin, I. V.; Maghrbi, Y.; Makonyi, K.; Müller, J.; Odenthal, T.; Piontek, D.; Schaepe, S.; Schmidt, Ch.; Schmieden, H.; Schmitz, R.; Seifen, T.; Thiel, A.; Thoma, U.; van Pee, H.; Walther, D.; Wendel, Ch.; Wiedner, U.; Wilson, A.; Winnebeck, A.; Zenke, F.

2013-12-01

The excitation function and momentum distribution of η‧ mesons have been measured in photon induced reactions on 12C in the energy range of 1250-2600 MeV. The experiment was performed with tagged photon beams from the ELSA electron accelerator using the Crystal Barrel and TAPS detectors. The data are compared to model calculations to extract information on the sign and magnitude of the real part of the η‧-nucleus potential. Within the model, the comparison indicates an attractive potential of -(37±10(stat)±10(syst)) MeV depth at normal nuclear matter density. Since the modulus of this depth is larger than the modulus of the imaginary part of the η‧-nucleus potential of -(10±2.5) MeV, determined by transparency ratio measurements, a search for resolved η‧-bound states appears promising.

Finite Element Analysis of Single Cell Stiffness Measurements Using PZT-Integrated Buckling Nanoneedles

PubMed Central

Rad, Maryam Alsadat; Tijjani, Auwal Shehu; Ahmad, Mohd Ridzuan; Auwal, Shehu Muhammad

2016-01-01

This paper proposes a new technique for real-time single cell stiffness measurement using lead zirconate titanate (PZT)-integrated buckling nanoneedles. The PZT and the buckling part of the nanoneedle have been modelled and validated using the ABAQUS software. The two parts are integrated together to function as a single unit. After calibration, the stiffness, Young’s modulus, Poisson’s ratio and sensitivity of the PZT-integrated buckling nanoneedle have been determined to be 0.7100 N·m−1, 123.4700 GPa, 0.3000 and 0.0693 V·m·N−1, respectively. Three Saccharomyces cerevisiae cells have been modelled and validated based on compression tests. The average global stiffness and Young’s modulus of the cells are determined to be 10.8867 ± 0.0094 N·m−1 and 110.7033 ± 0.0081 MPa, respectively. The nanoneedle and the cell have been assembled to measure the local stiffness of the single Saccharomyces cerevisiae cells The local stiffness, Young’s modulus and PZT output voltage of the three different size Saccharomyces cerevisiae have been determined at different environmental conditions. We investigated that, at low temperature the stiffness value is low to adapt to the change in the environmental condition. As a result, Saccharomyces cerevisiae becomes vulnerable to viral and bacterial attacks. Therefore, the proposed technique will serve as a quick and accurate process to diagnose diseases at early stage in a cell for effective treatment. PMID:28025571

Characterization of bone-implant fixation using modal analysis: Application to a press-fit implant model

PubMed Central

Swider, P.; Guérin, G.; Baas, Joergen; Søballe, Kjeld; Bechtold, Joan E.

2013-01-01

Orthopaedic implant fixation is strongly dependant upon the effective mechanical properties of newly formed tissue. In this study, we evaluated the potential of modal analysis to derive viscoelastic properties of periprosthetic tissue. We hypothesized that Young's modulus and loss factor could be obtained by a combined theoretical, computational and experimental modal analysis approach. This procedure was applied to ex vivo specimens from a cylindrical experimental implant placed in cancellous bone in an unloaded press-fit configuration, obtained after a four week observation period. Four sections each from seven textured titanium implants were investigated. The first resonant frequency and loss factor were measured. Average experimentally determined loss factor was 2% (SD 0.4%) and average first resonant frequency was 2.1 KHz (SD: 50). A 2D axisymmetric finite element (FE) model identified effective Young's modulus of tissue using experimental resonant frequencies as input. Average value was 42 MPa (SD: 2.4) and no significant difference between specimens was observed. In this pilot study, the non-destructive method allowed accurate measure of dynamic loss factor and resonant frequency and derivation of effective Young's modulus. Prior to implementing this dynamic protocol for broader mechanical evaluation of experimental implant fixation, further work is needed to determine if this affects results from subsequent destructive shear push-out tests. PMID:19464687

Optical properties and indentation hardness of thin-film acrylated epoxidized oil

NASA Astrophysics Data System (ADS)

Rahman, Mohammad Syuhaimi Ab.; Shaktur, Khaled Mohamed; Mohammad, Rahmah; Zalikha, Wan Aimi; Nawi, Norwimie; Mohd, Ahmad Faiza

2012-02-01

Epoxy acrylate has been widely used as optical resin for applications such as cladding, the core of a waveguide, and other photonic devices. In this study, sustainable resin from edible oil was used as an alternative to epoxy acrylate. Structural features and the transmission of planar thin-film resin from an ultraviolet-visible spectroscopy (UV-VIS) spectrometer were investigated upon UV exposure. It was found that high transmission still persists for all samples with and without an UV absorber for exposed and unexposed samples. The film was found to absorb strongly below 400 nm. A change in the cut-off wavelength was observed upon exposure. Thin-film hardness and its dynamic indentation in the load-unload mode with different test forces were evaluated. Vickers hardness and the elastic modulus were determined for unacrylated epoxidized soybean oil (ESO) and acrylated epoxidized soybean oil (AESO). It was found that the AESO has a higher Vickers hardness and elastic modulus than those of unacrylated thin film. The Vickers hardness and elastic modulus were found to increase as the applied test force increased. The refractive index, thickness, and modes present were characterized from a spin-coated planar thin film. The refractive index in the transverse electric mode (TE) and transverse magnetic mode (TM) were determined and compared for unacrylated and acrylated epoxidized oil.

Thermal equation of state of silicon carbide

NASA Astrophysics Data System (ADS)

Wang, Yuejian; Liu, Zhi T. Y.; Khare, Sanjay V.; Collins, Sean Andrew; Zhang, Jianzhong; Wang, Liping; Zhao, Yusheng

2016-02-01

A large volume press coupled with in-situ energy-dispersive synchrotron X-ray was used to probe the change of silicon carbide (SiC) under high pressure and temperature (P-T) up to 8.1 GPa and 1100 K. The obtained pressure-volume-temperature data were fitted to a modified high-T Birch-Murnaghan equation of state, yielding values of a series of thermo-elastic parameters, such as the ambient bulk modulus KTo = 237(2) GPa, temperature derivative of the bulk modulus at a constant pressure (∂K/∂T)P = -0.037(4) GPa K-1, volumetric thermal expansivity α(0, T) = a + bT with a = 5.77(1) × 10-6 K-1 and b = 1.36(2) × 10-8 K-2, and pressure derivative of the thermal expansion at a constant temperature (∂α/∂P)T = 6.53 ± 0.64 × 10-7 K-1 GPa-1. Furthermore, we found the temperature derivative of the bulk modulus at a constant volume, (∂KT/∂T)V, equal to -0.028(4) GPa K-1 by using a thermal pressure approach. In addition, the elastic properties of SiC were determined by density functional theory through the calculation of Helmholtz free energy. The computed results generally agree well with the experimentally determined values.

Tooth and bone deformation: structure and material properties by ESPI

NASA Astrophysics Data System (ADS)

Zaslansky, Paul; Shahar, Ron; Barak, Meir M.; Friesem, Asher A.; Weiner, Steve

2006-08-01

In order to understand complex-hierarchical biomaterials such as bones and teeth, it is necessary to relate their structure and mechanical-properties. We have adapted electronic speckle pattern-correlation interferometry (ESPI) to make measurements of deformation of small water-immersed specimens of teeth and bones. By combining full-field ESPI with precision mechanical loading we mapped sub-micron displacements and determined material-properties of the samples. By gradually and elastically compressing the samples, we compensate for poor S/N-ratios and displacement differences of about 100nm were reliably determined along samples just 2~3mm long. We produced stress-strain curves well within the elastic performance range of these materials under biologically relevant conditions. For human tooth-dentin, Young's modulus in inter-dental areas of the root is 40% higher than on the outer sides. For cubic equine bone samples the compression modulus of axial orientations is about double the modulus of radial and tangential orientations (20 GPa versus 10 GPa respectively). Furthermore, we measured and reproduced a surprisingly low Poisson's ratio, which averaged about 0.1. Thus the non-contact and non-destructive measurements by ESPI produce high sensitivity analyses of mechanical properties of mineralized tissues. This paves the way for mapping deformation-differences of various regions of bones, teeth and other biomaterials.

Rheological Characterization as an Alternative Method to Indentation for Determining the Setting Time of Restorative and Endodontic Cements

PubMed Central

Nicholson, Timothy M.; Kahler, Bill

2017-01-01

This study explored an alternative approach using rheology to assess setting time. The following cements were tested: ProRoot® MTA (Dentsply, Tulsa, OK, USA), Biodentine® (Septodont, Saint Maur des Fosses, France), Fuji VII®, FujiVII® EP, and Fuji IX® (from GC Corporation, Tokyo, Japan), RealSeal SE™ Sealer (SybronEndo, Amersfoort, The Netherlands), AH 26® and AH Plus (both from Dentsply DeTrey, Konstanz, Germany). Freshly mixed cements were placed into a strain-controlled rheometer (1 rad·s−1 with an applied strain of 0.01%). From measurements of elastic modulus over time, the time taken to reach 90% of the plateau elastic modulus (designated as the setting time) was determined for each cement. In increasing order, the setting times were as follows: Fuji VII EP 3.3 min, Fuji VII 3.6 min, Fuji IX 3.7 min, ProRoot MTA 5.1 min, Biodentine 15.9 min, RealSeal 22.2 min, AH Plus 5933 min, and AH 26 5067 min. However, ProRoot MTA did not yield reliable results. The time to reach the 90% plateau elastic modulus correlates well with the setting time of glass ionomer cements and Biodentine. Using this approach gives much longer setting times for endodontic sealers than previously recognized. PMID:29261125

Probabilistic homogenization of random composite with ellipsoidal particle reinforcement by the iterative stochastic finite element method

NASA Astrophysics Data System (ADS)

Sokołowski, Damian; Kamiński, Marcin

2018-01-01

This study proposes a framework for determination of basic probabilistic characteristics of the orthotropic homogenized elastic properties of the periodic composite reinforced with ellipsoidal particles and a high stiffness contrast between the reinforcement and the matrix. Homogenization problem, solved by the Iterative Stochastic Finite Element Method (ISFEM) is implemented according to the stochastic perturbation, Monte Carlo simulation and semi-analytical techniques with the use of cubic Representative Volume Element (RVE) of this composite containing single particle. The given input Gaussian random variable is Young modulus of the matrix, while 3D homogenization scheme is based on numerical determination of the strain energy of the RVE under uniform unit stretches carried out in the FEM system ABAQUS. The entire series of several deterministic solutions with varying Young modulus of the matrix serves for the Weighted Least Squares Method (WLSM) recovery of polynomial response functions finally used in stochastic Taylor expansions inherent for the ISFEM. A numerical example consists of the High Density Polyurethane (HDPU) reinforced with the Carbon Black particle. It is numerically investigated (1) if the resulting homogenized characteristics are also Gaussian and (2) how the uncertainty in matrix Young modulus affects the effective stiffness tensor components and their PDF (Probability Density Function).

AFM nanoscale indentation in air of polymeric and hybrid materials with highly different stiffness

NASA Astrophysics Data System (ADS)

Suriano, Raffaella; Credi, Caterina; Levi, Marinella; Turri, Stefano

2014-08-01

In this study, nanomechanical properties of a variety of polymeric materials was investigated by means of AFM. In particular, selecting different AFM probes, poly(methyl methacrylate) (PMMA), polydimethylsiloxane (PDMS) bulk samples, sol-gel hybrid thin films and hydrated hyaluronic acid hydrogels were indented in air to determine the elastic modulus. The force-distance curves and the indentation data were found to be greatly affected by the cantilever stiffness and by tip geometry. AFM indentation tests show that the choice of the cantilever spring constant and of tip shape is crucially influenced by elastic properties of samples. When adhesion-dominated interactions occur between the tip and the surface of samples, force-displacement curves reveal that a suitable functionalization of AFM probes allows the control of such interactions and the extraction of Young' modulus from AFM curves that would be otherwise unfeasible. By applying different mathematical models depending on AFM probes and materials under investigation, the values of Young's modulus were obtained and compared to those measured by rheological and dynamic mechanical analysis or to literature data. Our results show that a wide range of elastic moduli (10 kPa-10 GPa) can be determined by AFM in good agreement with those measured by conventional macroscopic measurements.