Many-nucleon transfer reactions at the coulomb barrier

International Nuclear Information System (INIS)

Wegmann, H.

1974-01-01

The aim of the present work was to investigate the many-nucleon transfer with heavy ion radiation near the coulomb barrier. The neutron-rich targets 76 Ge, sup(92,94,96)Zr and 100 Mo were thus irradiated with 32 S and 34 S radiation. By measuring the activity of the back-scattered light reaction products in the transfer, total cross sections were determined for the 3p, 4p, 3pn, 4pn, 3n, 4n and 6n transfer. Excitation functions for the 3p, 4p, 3pn and 4pn transfer were measured for the target-projectile combination 96 Zr- 32 S. Differential cross sections could be determined with 96 Zr and 100 Mo. The results were compared with various theoretical calculations. (orig./LH) [de

6,7Li + 28Si total reaction cross sections at near barrier energies

International Nuclear Information System (INIS)

Pakou, A.; Musumarra, A.; Pierroutsakou, D.; Alamanos, N.; Assimakopoulos, P.A.; Divis, N.; Doukelis, G.; Gillibert, A.; Harissopulos, S.; Kalyva, G.; Kokkoris, M.; Lagoyannis, A.; Mertzimekis, T.J.; Nicolis, N.G.; Papachristodoulou, C.; Perdikakis, G.; Roubos, D.; Rusek, K.; Spyrou, S.; Zarkadas, Ch.

2007-01-01

Total reaction cross section measurements for the 6,7 Li + 28 Si systems have been performed at near-barrier energies. The results indicate that, with respect to the potential anomaly at barrier, 6 Li and 7 Li on light targets exhibit similar energy dependence on the imaginary potential. Comparisons are made with 6,7 Li cross sections on light and heavy targets, extracted via previous elastic scattering measurements and also with CDCC calculations. Energy dependent parametrisations are also obtained for total reaction cross sections of 6,7 Li on Si, as well as on any target, at near barrier energies

Barriers for recess physical activity

DEFF Research Database (Denmark)

Pawlowski, Charlotte Skau; Tjørnhøj-Thomsen, Tine; Schipperijn, Jasper

2014-01-01

BACKGROUND: Many children, in particular girls, do not reach the recommended amount of daily physical activity. School recess provides an opportunity for both boys and girls to be physically active, but barriers to recess physical activity are not well understood. This study explores gender...... differences in children's perceptions of barriers to recess physical activity. Based on the socio-ecological model four types of environmental barriers were distinguished: natural, social, physical and organizational environment. METHODS: Data were collected through 17 focus groups (at 17 different schools...... this study, we recommend promoting recess physical activity through a combination of actions, addressing barriers within the natural, social, physical and organizational environment....

Comparative studies for different proximity potentials applied to sub-barrier fusion reactions

Energy Technology Data Exchange (ETDEWEB)

Zhang, G.L. [Beihang University, School of Physics and Nuclear Energy Engineering, Beijing (China); Beihang University, Key Laboratory of Micro-Nano Measurement-Manipulation and Physics (Ministry of Education), Beijing (China); Qu, W.W. [Medical College of Soochow University, School of Radiation Medicine and Protection, Soochow (China); Guo, M.F.; Qian, J.Q. [Beihang University, School of Physics and Nuclear Energy Engineering, Beijing (China); Zhang, H.Q. [China Institute of Atomic Energy, Beijing (China); Wolski, R. [Henryk Niewodniczanski Institute of Nuclear Physics PAS, Cracow (Poland)

2016-02-15

Coulomb barrier heights calculated by using 14 different versions of proximity potentials are studied and applied for experimental data of fusion in terms of a recently proposed energy scaling approach. The results show that the descriptions of proximity potentials 77 and 88 for the barrier heights seem to be closest to the values required by the systematics. On the basis of proximity potential 77, the parameterized formulas of the barrier height and radius are obtained. These formulas can calculate the barrier positions and barrier heights reasonably well within the error, respectively. Thus it provides a simple and direct way to calculate the barrier positions and barrier heights for heavy-ion fusion reactions. (orig.)

Dynamical barrier and isotope effects in the simplest substitution reaction via Walden inversion mechanism

Science.gov (United States)

Zhao, Zhiqiang; Zhang, Zhaojun; Liu, Shu; Zhang, Dong H.

2017-02-01

Reactions occurring at a carbon atom through the Walden inversion mechanism are one of the most important and useful classes of reactions in chemistry. Here we report an accurate theoretical study of the simplest reaction of that type: the H+CH4 substitution reaction and its isotope analogues. It is found that the reaction threshold versus collision energy is considerably higher than the barrier height. The reaction exhibits a strong normal secondary isotope effect on the cross-sections measured above the reaction threshold, and a small but reverse secondary kinetic isotope effect at room temperature. Detailed analysis reveals that the reaction proceeds along a path with a higher barrier height instead of the minimum-energy path because the umbrella angle of the non-reacting methyl group cannot change synchronously with the other reaction coordinates during the reaction due to insufficient energy transfer from the translational motion to the umbrella mode.

Probing cluster structures through sub-barrier transfer reactions

Directory of Open Access Journals (Sweden)

Rafferty D. C.

2016-01-01

Full Text Available Multinucleon transfer probabilities and excitation energy distributions have been measured in 16,18O, 19F + 208Pb at energies between 90% - 100% of the Coulomb barrier. A strong 2p2n enhancement is observed for all reactions, though most spectacularly in the 18O induced reaction. Results are interpreted in terms of the Semiclassical model, which seems to suggest α-cluster transfer in all studied systems. The relation to cluster-states in the projectile is discussed, with the experimental results consistent with previous structure studies. Dissipation of energy in the collisions of 18O is compared between different reaction modes, with cluster transfer associated with dissipation over a large number of internal states. Cluster transfer is shown to be a long range dissipation mechanism, which will inform the development of future models to treat these dynamic processes in reactions.

Fusion reaction around the Coulomb barrier with neutron-rich nuclei

Energy Technology Data Exchange (ETDEWEB)

Yoshida, Atsushi [Institute of Physical and Chemical Research, Wako, Saitama (Japan)

1997-07-01

Two fusion reactions with neutron-rich nuclei are reported in this work. On the first reaction: {sup 9,10,11}Be+{sup 209}Bi, the fusion cross sections around the coulomb barrier were measured by determing {alpha} disintegration from compound nucleus Fr. In the field of 10-100 mb, the same total fusion cross sections were obtained. The phenomenon {sup 11}Be(neutron halo nucleus) alone increased and decreased was not observed. The fusion cross sections of {sup 27,29,31}Al+{sup 197}Au system were determined by using 130 kcps and 30 kcps of beam strength of {sup 29,31}Al, respectively. The value of {sup 27}Al was reproduced by calculation, but that of {sup 29}Al increased around barrier which could not be explained by CCDEF calculation. (S.Y.)

Observation of the one- to six-neutron transfer reactions at sub-barrier energies

Energy Technology Data Exchange (ETDEWEB)

Jiang, C.L.; Rehm, K.E.; Gehring, J. [and others

1995-08-01

It was suggested many years ago that when two heavy nuclei are in contact during a grazing collision, the transfer of several correlated neutron-pairs could occur. Despite considerable experimental effort, however, so far only cross sections for up to four-neutron transfers have been uniquely identified. The main difficulties in the study of multi-neutron transfer reactions are the small cross sections encountered at incident energies close to the barrier, and various experimental uncertainties which can complicate the analysis of these reactions. We have for the first time found evidence for multi-neutron transfer reactions covering the full sequence from one- to six-neutron transfer reactions at sub-barrier energies in the system {sup 58}Ni + {sup 100}Mo.

Fusability and fissionability in 86Kr induced reactions near and below the fusion barrier

International Nuclear Information System (INIS)

Reisdorf, W.; Hessberger, F.P.; Hildenbrand, K.D.; Hofmann, S.; Muenzenberg, G.; Schmidt, K.H.; Schneider, W.F.W.; Suemmerer, K.; Wirth, G.; Kratz, J.V.; Schlitt, K.; Sahm, C.C.

1985-04-01

Evaporation-residue excitation functions for the reactions 86 Kr + sup(70,76)Ge, sup(92,100)Mo, sup(99,102,104)Ru have been measured using activation methods and the velocity filter SHIP. The data span the region from well below the fusion barrier up to and beyond the energy where limitation by fission competition takes place. The data are shown to be compatible with the concept of complete fusion followed by the statistical decay of the equilibrated compound nucleus. Information on both the fusion probability at and below the fusion threshold and the fissionability of the compound nuclei formed is extracted. The model dependence of the extracted fission barriers is discussed in detail. In analogy to studies involving lighter projectiles, strong correlations between the low-energy nuclear-structure properties of the nuclei and the subbarrier fusion probability are found. A relative shift of the fusion barrier to higher energies, that increases with the number of valence neutrons in the target nuclei, is observed. (orig.)

Recent developments in heavy-ion fusion reactions around the Coulomb barrier

Directory of Open Access Journals (Sweden)

Hagino K.

2016-01-01

Full Text Available The nuclear fusion is a reaction to form a compound nucleus. It plays an important role in several circumstances in nuclear physics as well as in nuclear astrophysics, such as synthesis of superheavy elements and nucleosynthesis in stars. Here we discuss two recent theoretical developments in heavy-ion fusion reactions at energies around the Coulomb barrier. The first topic is a generalization of the Wong formula for fusion cross sections in a single-channel problem. By introducing an energy dependence to the barrier parameters, we show that the generalized formula leads to results practically indistinguishable from a full quantal calculation, even for light symmetric systems such as 12C+12C, for which fusion cross sections show an oscillatory behavior. We then discuss a semi-microscopic modeling of heavy-ion fusion reactions, which combine the coupled-channels approach to the state-of-the-art nuclear structure calculations for low-lying collective motions. We apply this method to subbarrier fusion reactions of 58Ni+58Ni and 40Ca+58Ni systems, and discuss the role of anharmonicity of the low-lying vibrational motions.

Effects of breakup of weakly bound projectile and neutron transfer on fusion reactions around Coulomb barrier

International Nuclear Information System (INIS)

Lin, C.J.; Zhang, H.Q.; Yang, F.; Ruan, M.; Liu, Z.H.; Wu, Y.W.; Wu, X.K.; Zhou, P.; Zhang, C.L.; Zhang, G.L.; An, G.P.; Jia, H.M.; Xu, X.X.

2007-01-01

The excitation functions of quasielastic and elastic scattering at backward angles have been measured for the systems of 16 O+ 152 Sm, 6,7 Li+ 208 Pb and 32 S+ 90,96 Zr. The barrier distributions are extracted from these measured excitation functions and compared with the corresponding fusion barrier distributions. Except some details, the barrier distributions derived from the data of fusion and quasielastic/elastic scattering are almost the same for the tightly bound reaction systems. For the reaction systems with weakly bound projectile, the barrier distributions extracted from quasielastic scattering are obviously different from the fusion barrier distributions. However, the barrier distributions extracted from the excitation functions of the quasielastic scattering plus breakup are almost the same as the one extracted from the complete fusion data. This result means that barrier distribution not only bears the information of nuclear structures but also contains the knowledge of reaction mechanisms. Our results show that the complete fusion of the weakly bound projectile with heavy target is suppressed at the above barrier energies as compared with the model predictions. In addition, the measured barrier distribution of 32 S+ 96 Zr is broaden and extends to lower energy than in the case of 32 S+ 90 Zr due to the coupling of neutron transfer with positive Q-values, which result in a significant enhancement of fusion cross sections at the subbarrier energies

Recent experimental results in sub- and near-barrier heavy-ion fusion reactions

Energy Technology Data Exchange (ETDEWEB)

Montagnoli, Giovanna [Dipartimento di Fisica e Astronomia, Universita di Padova (Italy); INFN Sezione di Padova (Italy); Stefanini, Alberto M. [INFN, Laboratori Nazionali di Legnaro, Legnaro (Padova) (Italy)

2017-08-15

Recent advances obtained in the field of near and sub-barrier heavy-ion fusion reactions are reviewed. Emphasis is given to the results obtained in the last decade, and focus is mainly on the experimental work performed concerning the influence of transfer channels on fusion cross sections and the hindrance phenomenon far below the barrier. Indeed, early data of sub-barrier fusion taught us that cross sections may strongly depend on the low-energy collective modes of the colliding nuclei, and, possibly, on couplings to transfer channels. The coupled-channels (CC) model has been quite successful in the interpretation of the experimental evidences. Fusion barrier distributions often yield the fingerprint of the relevant coupled channels. Recent results obtained by using radioactive beams are reported. At deep sub-barrier energies, the slope of the excitation function in a semi-logarithmic plot keeps increasing in many cases and standard CC calculations overpredict the cross sections. This was named a hindrance phenomenon, and its physical origin is still a matter of debate. Recent theoretical developments suggest that this effect, at least partially, may be a consequence of the Pauli exclusion principle. The hindrance may have far-reaching consequences in astrophysics where fusion of light systems determines stellar evolution during the carbon and oxygen burning stages, and yields important information for exotic reactions that take place in the inner crust of accreting neutron stars. (orig.)

Barriers to physical activity among working mothers.

Science.gov (United States)

Dombrowski, Jill J

2011-04-01

Working mothers experience several barriers to physical activity. If these barriers can be identified by occupational health nurses and they can partner with working mothers to reduce these perceived barriers, the health of these workers can be improved and chronic disease risk prevented. The purpose of this study was to measure the effect of self-regulatory efficacy on physical activity among working mothers and to describe specific barriers to physical activity. The Barriers Specific Self-Efficacy Scale (BARSE) and the Kaiser Physical Activity Survey (KPAS) were used to measure the variables. Self-regulatory efficacy was found to be a strong predictor of physical activity in a diverse sample of working mothers who did not meet current recommendations for physical activity. Occupational health nurses can use these findings to design programs for groups and for counseling individuals. Copyright 2011, SLACK Incorporated.

Surface-Activated Coupling Reactions Confined on a Surface.

Science.gov (United States)

Dong, Lei; Liu, Pei Nian; Lin, Nian

2015-10-20

-functional theory (DFT) transition-state calculations have been used to shed light on reaction mechanisms and to unravel the trends of different surface materials. In this Account, we discuss recent progress made in two widely studied surface-confined coupling reactions, aryl-aryl (Ullmann-type) coupling and alkyne-alkyne (Glaser-type) coupling, and focus on surface activation effects. Combined experimental and theoretical studies on the same reactions taking place on different metal surfaces have clearly demonstrated that different surfaces not only reduce the reaction barrier differently and render different reaction pathways but also control the morphology of the reaction products and, to some degree, select the reaction products. We end the Account with a list of questions to be addressed in the future. Satisfactorily answering these questions may lead to using the surface-confined coupling reactions to synthesize predefined products with high yield.

Barriers to Physical Activity on University Student

Science.gov (United States)

Jajat; Sultoni, K.; Suherman, A.

2017-03-01

The purpose of the research is to analyze the factors that become barriers to physical activity in university students based on physical activity level. An internet-based survey was conducted. The participants were 158 University students from Universitas Pendidikan Indonesia. Barriers to Physical Activity Quiz (BPAQ) were used to assessed the factors that become barriers to physical activity in university students. IPAQ (short form) were used to assessed physical activity level. The results show there was no differences BPAQ based on IPAQ level. But when analyzed further based on seven factors barriers there are differences in factors “social influence and lack of willpower” based IPAQ level. Based on this it was concluded that the “influence from other and lack of willpower” an inhibiting factor on students to perform physical activity.

[Prevalence of barriers for physical activity in adolescents].

Science.gov (United States)

Santos, Mariana Silva; Hino, Adriano Akira Ferreira; Reis, Rodrigo Siqueira; Rodriguez-Añez, Ciro Romélio

2010-03-01

The aim of this study was to analyze the prevalence and association of barriers to physical activity among adolescents. This cross-sectional study evaluated a representative sample of public high school students in Curitiba-PR, Brazil. A total of 1,609 school adolescents (59.7% male) between 14 and 18 years of age answered a questionnaire on physical activity status and barriers to physical activity. Logistic regressions were conducted for each barrier investigated to verify the association between the prevalence of barriers and physical activity, adjusting for confounding variables (age and socioeconomic status). Analyses were done separately for boys and girls. Only 22% of boys and 9% of girls achieved the current physical activity recommendation. Among the 12 barriers investigated, only "there is nobody to take" did not differ between boys and girls. The perception of barriers was higher for girls than boys (p barriers. "Lack of friends company" and "feel lazy" were the barriers most often reported by boys (30.4%) and girls (51.8%) respectively; however, the barrier most strongly associated with prevalence of physical inactivity was "prefer to do other things" for both boys (OR = 5.02 (2.69 - 9.37); p barriers for the practice of physical activity were more prevalent in girls and differed as to the extent of importance between genders.

Faculty Perceptions about Barriers to Active Learning

Science.gov (United States)

Michael, Joel

2007-01-01

Faculty may perceive many barriers to active learning in their classrooms. Four groups of participants in a faculty development workshop were asked to list their perceived barriers to active learning. Many of the problems identified were present on more than one list. The barriers fall into three categories: student characteristics, issues…

Super-multi-nucleon transfer observed in 60Ni+124Sn reaction slightly above the barrier

International Nuclear Information System (INIS)

Tomasi, E.; Pravikoff, M.S.; Nolte, E.; Morinaga, H.

1982-01-01

In order to investigate the behaviour of nucleon transfer near the Coulomb barrier through the produced radioactivities, we have studied the 60 Ni+ 124 Sn system, the residual activity measurements were done at three lab energies of 237, 247 and 258 MeV (Bsub(c)(lab) = 234 MeV). For the highest energy we measured also the angular distribution. In addition to activities corresponding to a few nucleon transfers and evaporation residues, a large number of radioactive nuclei was found, which could be attributed to another class of reaction mechanism. Here, we report on this new phenomenon, which might be due to a super-multi-nucleon transfer, on the basis of the measured angular and mass distributions

Physical protection system using activated barriers

International Nuclear Information System (INIS)

Timm, R.E.; Zinneman, T.E.; Haumann, J.R.; Flaugher, H.A.; Reigle, D.L.

1984-03-01

The Argonne National Laboratory has recently installed an activated barrier, the Access Denial System, to upgrade its security. The technology of this system was developed in the late 70's by Sandia National Laboratory-Albuquerque. The Argonne National Laboratory is the first Department of Energy facility to use this device. Recent advancements in electronic components provide the total system support that makes the use of an activated barrier viable and desirable. The premise of an activated barrier is that it is deployed after a positive detection of an adversary is made and before the adversary can penetrate vital area. To accomplish this detection, sophisticated alarms, assessment, and communications must be integrated into a system that permits a security inspector to make a positive evaluation and to activate the barrier. The alarm sensor locations are selected to provide protection in depth. Closed circuit television is used with components that permit multiple video frames to be stored for automated, priority-based playback to the security inspector. Further, algorithms permit look-ahead surveillance of vital areas so that the security inspector can activate the access denial system in a timely manner and not be restricted to following the adversaries' penetration path(s)

Complete and incomplete fusion dynamics of {sup 6,7}Li + {sup 159}Tb reactions near the Coulomb barrier

Energy Technology Data Exchange (ETDEWEB)

Gautam, Manjeet Singh [Thapar University, School of Physics and Materials Science, Patiala (India); Indus Degree College, Department of Physics, Kinana, Jind, Haryana (India); Grover, Neha; Sharma, Manoj K. [Thapar University, School of Physics and Materials Science, Patiala (India)

2017-01-15

The complete fusion (CF) and incomplete fusion (ICF) cross-sections are estimated for {sup 6,} {sup 7}Li + {sup 159}Tb reactions using the energy-dependent Woods-Saxon potential model (EDWSP model) and dynamical cluster-decay model (DCM). The CF data of the {sup 6}Li + {sup 159}Tb({sup 7}Li + {sup 159}Tb) reaction at above barrier energies is suppressed with reference to expectations of the EDWSP model by 25% (20%) which is smaller than the reported data by ∝ 9% (6%). This suppression is correlated with the projectile breakup effect. The projectiles {sup 6,7}Li are loosely bound systems, which may break up into charged fragments prior to reaching the fusion barrier and subsequently one of the fragment is captured by the target leading to the suppression of fusion data at above barrier energies. The sum of CF and ICF, which is termed as total fusion cross-section (TF), removes the discrepancies between theoretical predictions and the above barrier complete fusion data and hence is adequately explained via the EDWSP model over a wide range of energy spread across the Coulomb barrier. In addition to fusion, the decay mechanism of {sup 6}Li + {sup 159}Tb reaction is studied within the framework of the dynamical cluster-decay model (DCM). The breakup of the projectile ({sup 6}Li) in the entrance channel indicates the presence of ICF, which is investigated further using the collective clusterization approach of DCM. The present theoretical analysis suggests that a larger barrier modification is needed to address the fusion data of chosen reactions in the below barrier energy region. (orig.)

Skin barrier homeostasis in atopic dermatitis: feedback regulation of kallikrein activity.

Directory of Open Access Journals (Sweden)

Reiko J Tanaka

Full Text Available Atopic dermatitis (AD is a widely spread cutaneous chronic disease characterised by sensitive reactions (eg. eczema to normally innocuous elements. Although relatively little is understood about its underlying mechanisms due to its complexity, skin barrier dysfunction has been recognised as a key factor in the development of AD. Skin barrier homeostasis requires tight control of the activity of proteases, called kallikreins (KLKs, whose activity is regulated by a complex network of protein interactions that remains poorly understood despite its pathological importance. Characteristic symptoms of AD include the outbreak of inflammation triggered by external (eg. mechanical and chemical stimulus and the persistence and aggravation of inflammation even if the initial stimulus disappears. These characteristic symptoms, together with some experimental data, suggest the presence of positive feedback regulation for KLK activity by inflammatory signals. We developed simple mathematical models for the KLK activation system to study the effects of feedback loops and carried out bifurcation analysis to investigate the model behaviours corresponding to inflammation caused by external stimulus. The model analysis confirmed that the hypothesised core model mechanisms capture the essence of inflammation outbreak by a defective skin barrier. Our models predicted the outbreaks of inflammation at weaker stimulus and its longer persistence in AD patients compared to healthy control. We also proposed a novel quantitative indicator for inflammation level by applying principal component analysis to microarray data. The model analysis reproduced qualitative AD characteristics revealed by this indicator. Our results strongly implicate the presence and importance of feedback mechanisms in KLK activity regulation. We further proposed future experiments that may provide informative data to enhance the system-level understanding on the regulatory mechanisms of skin barrier

Sub-barrier quasifission in heavy element formation reactions with deformed actinide target nuclei

Science.gov (United States)

Hinde, D. J.; Jeung, D. Y.; Prasad, E.; Wakhle, A.; Dasgupta, M.; Evers, M.; Luong, D. H.; du Rietz, R.; Simenel, C.; Simpson, E. C.; Williams, E.

2018-02-01

Background: The formation of superheavy elements (SHEs) by fusion of two massive nuclei is severely inhibited by the competing quasifission process. Low excitation energies favor SHE survival against fusion-fission competition. In "cold" fusion with spherical target nuclei near 208Pb, SHE yields are largest at beam energies significantly below the average capture barrier. In "hot" fusion with statically deformed actinide nuclei, this is not the case. Here the elongated deformation-aligned configurations in sub-barrier capture reactions inhibits fusion (formation of a compact compound nucleus), instead favoring rapid reseparation through quasifission. Purpose: To determine the probabilities of fast and slow quasifission in reactions with prolate statically deformed actinide nuclei, through measurement and quantitative analysis of the dependence of quasifission characteristics at beam energies spanning the average capture barrier energy. Methods: The Australian National University Heavy Ion Accelerator Facility and CUBE fission spectrometer have been used to measure fission and quasifission mass and angle distributions for reactions with projectiles from C to S, bombarding Th and U target nuclei. Results: Mass-asymmetric quasifission occurring on a fast time scale, associated with collisions with the tips of the prolate actinide nuclei, shows a rapid increase in probability with increasing projectile charge, the transition being centered around projectile atomic number ZP=14 . For mass-symmetric fission events, deviations of angular anisotropies from expectations for fusion fission, indicating a component of slower quasifission, suggest a similar transition, but centered around ZP˜8 . Conclusions: Collisions with the tips of statically deformed prolate actinide nuclei show evidence for two distinct quasifission processes of different time scales. Their probabilities both increase rapidly with the projectile charge. The probability of fusion can be severely

Transport of the moving barrier driven by chiral active particles

Science.gov (United States)

Liao, Jing-jing; Huang, Xiao-qun; Ai, Bao-quan

2018-03-01

Transport of a moving V-shaped barrier exposed to a bath of chiral active particles is investigated in a two-dimensional channel. Due to the chirality of active particles and the transversal asymmetry of the barrier position, active particles can power and steer the directed transport of the barrier in the longitudinal direction. The transport of the barrier is determined by the chirality of active particles. The moving barrier and active particles move in the opposite directions. The average velocity of the barrier is much larger than that of active particles. There exist optimal parameters (the chirality, the self-propulsion speed, the packing fraction, and the channel width) at which the average velocity of the barrier takes its maximal value. In particular, tailoring the geometry of the barrier and the active concentration provides novel strategies to control the transport properties of micro-objects or cargoes in an active medium.

H + H2 reaction barrier: A fixed-node quantum Monte Carlo study

International Nuclear Information System (INIS)

Barnett, R.N.; Reynolds, P.J.; Lester, W.A. Jr.

1985-01-01

The classical barrier height for the H+H 2 exchange reaction, as well as the energies at two other points along the reaction path, are calculated using fixed-node quantum Monte Carlo (FNQMC). Several single-determinant importance functions are used at the saddle point in order to relate the quality of the importance function to the accuracy and precision of the final result. The computed barrier is an upper bound since the energy of H and of H 2 is obtained exactly by FNQMC. Our best upper bound (9.70 +- 0.13 kcal/mol) has a mean within 0.1 kcal/mol of the presumed exact value. This best bound is obtained with a single determinant, double-zeta basis importance function. Contrary to experience with expansion methods, it is found that an importance function with a basis set of near Hartree--Fock quality, as well as one derived from a spin-unrestricted SCF calculation, are among the least efficient and least accurate of the importance functions used. Specifically, a nodal surface appearing in the lowest energy molecular orbital in these functions apparently increases the FNQMC energy. The FNQMC energy at the two other points along the reaction path is found to agree with the most accurate CI results of Liu to within statistical error

Perceived barriers to physical activity among Nigerian stroke survivors.

Science.gov (United States)

Idowu, Opeyemi Ayodiipo; Adeniyi, Ade Fatai; Ogwumike, Omoyemi Olubunmi; Fawole, Henrietta Oluwafunmilola; Akinrolie, Olayinka

2015-01-01

Benefits of physical activity in the prevention and management of stroke are well documented in the literature. There is increasing evidence that stroke survivors in South-West Nigeria are physically inactive. Data on barriers to the achievement of the recommended physical activity levels including its differences along socio-demographic characteristics among stroke survivors in South-West Nigeria are needed. The Exercise Benefits and Barrier Scale and the International Physical Activity Questionnaire were administered on 121 stroke survivors to determine their perceived barriers to physical activity and physical activity levels respectively. Information on socio-demographic data and clinical variables were also collected. The sample included 70.2% males, with majority of the participants reporting low physical activity levels (80.2%) and high perceived barriers (Mean = 48.13, SD = 7.88). The four most reported common barriers among stroke survivors were access to exercise facilities (95.0%), being embarrassed to exercise (94.2%), economic cost demands of exercise (94.2%) and notion that people in exercise clothes look funny (94.2%) respectively. There were no significant differences found in barriers to physical activity between gender (U = 1471.00, P = 0.74) and across each of: occupational status (H = 4.37, P = 0.22), age group (H = 0.82, P = 0.84) and educational levels (H = 4.56, P = 0.33). Significant difference however existed in perceived barriers across marital status categories (H = 12.87, P = 0.05). Stroke survivors indicated high perceived barriers to physical activity and these barriers were associated with marital status.

Calcium-Magnesium-Aluminosilicate (CMAS) Reactions and Degradation Mechanisms of Advanced Environmental Barrier Coatings

Science.gov (United States)

Ahlborg, Nadia L.; Zhu, Dongming

2013-01-01

The thermochemical reactions between calcium-magnesium-aluminosilicate- (CMAS-) based road sand and several advanced turbine engine environmental barrier coating (EBC) materials were studied. The phase stability, reaction kinetics and degradation mechanisms of rare earth (RE)-silicates Yb2SiO5, Y2Si2O7, and RE-oxide doped HfO2 and ZrO2 under the CMAS infiltration condition at 1500 C were investigated, and the microstructure and phase characteristics of CMAS-EBC specimens were examined using Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD). Experimental results showed that the CMAS dissolved RE-silicates to form crystalline, highly non-stoichiometric apatite phases, and in particular attacking the silicate grain boundaries. Cross-section images show that the CMAS reacted with specimens and deeply penetrated into the EBC grain boundaries and formed extensive low-melting eutectic phases, causing grain boundary recession with increasing testing time in the silicate materials. The preliminary results also showed that CMAS reactions also formed low melting grain boundary phases in the higher concentration RE-oxide doped HfO2 systems. The effect of the test temperature on CMAS reactions of the EBC materials will also be discussed. The faster diffusion exhibited by apatite and RE-doped oxide phases and the formation of extensive grain boundary low-melting phases may limit the CMAS resistance of some of the environmental barrier coatings at high temperatures.

Role of transfer reactions in heavy-ion collisions at the Coulomb barrier

Directory of Open Access Journals (Sweden)

Pollarolo Giovanni

2011-10-01

Full Text Available One and two neutron transfer reactions are discussed in the semiclassical formalism. The twoneutrons transfer cross sections are calculated in the successive approximation. Comparisons with new experimental data below the Coulomb barrier are discussed in term of transfer probabilities as a function of the distance of closest approach for Coulomb scattering.

Multi-nucleon transfer: a probe to investigate the reaction mechanism around the barrier

International Nuclear Information System (INIS)

Mandal, Samit K.

2014-01-01

The investigation of multi-nucleon transfer mechanism offers valuable information on the pairing interactions that enhance the transfer of nucleon pairs across heavy ions involved in the reaction. These reactions are also a useful tool to study exotic nuclei far from the stability line, which can be explored with the new generation radioactive beam facility. In this talk, multi-nucleon transfer reaction mechanisms between heavy ions and their effect on the reaction dynamics around the coulomb barrier energies have been discussed. Experimental results will be presented with a semi classical description of multi nucleon transfer reaction calculation. One and two nucleon transfer cross sections reproduced using a quantum mechanical coupled channel calculations will also be discussed. A feasibility of investigation of multi-nucleon transfer mechanism to explore the pairing correlation at moderate spin states with radioactive beams will be discussed. (author)

Promoting Physical Activity: Addressing Barriers and Moving Forward

Science.gov (United States)

Beighle, Aaron; Morrow, James R.

2014-01-01

The barriers that keep individuals from adopting and maintaining active lifestyles are very complex. Strategies for overcoming these barriers and to incentivize and assist inactive individuals to benefit from physical activity are necessary. In addition, it is important to examine the impact of public policy on active living. As youth physical…

Barriers to outdoor physical activity in wintertime among Somali youth.

Science.gov (United States)

Rothe, Elizabeth; Holt, Christina; Kuhn, Celine; McAteer, Timothy; Askari, Isabella; O'Meara, Mary; Sharif, Abdimajid; Dexter, William

2010-10-01

To identify barriers to outdoor physical activity in winter among Somali youth in Maine. Despite the many proven health benefits of physical activity among children, such as cardiovascular fitness and health status as an adult, there has been a decrease in physical activity among children in recent years. Specifically, children who are of low socio-economic status or are from communities where many immigrants are at increased risk for developing obesity. Immigrants are also less likely to be physically active. There are many potential barriers to wintertime physical activity among Somali youth in Maine, such as lack of financial resources, transportation, proper winter clothing, and appropriate knowledge of winter safety, and language and cultural barriers. For females, different attire required for outdoor activity may be a barrier. Somali parents and children were recruited from Portland, Maine to participate in focus groups led by a trained facilitator with a Somali translator and cultural broker. Transcripts were coded using NVIVO software to identify barriers to physical activity among Somali youth outside in winter. Eight focus groups were conducted. Sixty-one Somali community members were recruited. Participants felt outdoor physical activity is important, but note that it is decreased in winter. Barriers to outdoor activity in winter cited by focus group participants were lack of resources, health concerns, gender barriers for females, and knowledge barriers. Concern over lack of supervision while children play outside was also cited. This study revealed many of the underlying beliefs, barriers and cultural issues that impact Somali families' intention to be active and ability to be active outdoors in winter. These findings can be used to generate research hypotheses and public health interventions regarding outdoor physical activity among Somali youth.

Fusion barrier distributions from capture and quasi-elastic excitation functions measured in reaction 36S, 48Ca, 64Ni+238U

International Nuclear Information System (INIS)

Kozulin, E. M.

2009-01-01

The subbarrier fusion enhancement in reactions with heavy ions were explained by taking into account coupling between relative motion and intrinsic degrees of freedom of interacting nuclei. The coupling of reaction channels manifests itself in the potential barrier between interacting nuclei giving rise to a distribution of fusion barrier instead of single barrier.Capture and quasi-elastic scattering excitation functions at backward angles were measured for 3 6S , 4 8C a, 6 4N i+2 38U reactions systems at energies close and below the Coulomb barrier (i.e. when the influence of the shell effects on the fusion and characteristics of the decay of the composite system is considerable). Representations of the barrier distributions were extracted from both capture and quasi-elastic data. The experimental representations of barrier distributions were compared with coupled-channel calculations using CCFULL code. The major part of these experiments has been performed at the U-400 accelerator of the Flerov Laboratory of Nuclear Reactions (JINR, Dubna); at the TANDEM-ALPI accelerator of the LNL (INFN, Legnaro, Italy) and at the Accelerator Laboratory of University of Jyvaeskylae (JYFL, Finland) using a time-of-flight spectrometer of fission fragments CORSET (CORrelation SET-up.) The extraction of the masses and Total Kinetic Energy (TKE) of the binary reaction products is based upon the analysis of the two-body velocity In the case of the fusion-fission and quasi-fission processes, the observed peculiarities of mass and energy distributions of the fragments, the ratio between the fusion-fission and quasi-fission cross sections are determined deformations of interaction nuclei and angular momentum carried in the di-nuclear system and the shell structure of the formed fragments. In this work, the high-precision capture and quasi-elastic scattering excitation function data are presented.The influence of projectile and target excitations and nucleon transfer on fusion barrier

Barriers to Physical Activity in Individuals with Spinal Cord Injury

DEFF Research Database (Denmark)

Roberton, Terri; Bucks, Romola S.; Skinner, Timothy C.

2011-01-01

This study examined barriers to physical activity reported individuals with spinal cord injury (SCI) and the degree to which these barriers differed across varying degrees of independence. Participants were 65 individuals recruited from the Western Australian Spinal Cord Injury database. Data...... on physical activity participation and perceived barriers to physical activity participation were collected using a cross-sectional survey and analysed using independent samples t-tests. We found that, regardless of level of ambulation or ability to transfer, few participants reported being physically active....... While there were no significant differences in the amount of barriers reported by individuals with different levels of independence, the type of barriers reported varied across groups....

Origins and implications of temperature-dependent activation energy barriers for dislocation nucleation in face-centered cubic metals

International Nuclear Information System (INIS)

Warner, D.H.; Curtin, W.A.

2009-01-01

The linking of atomistic simulations of stress-driven processes to experimentally observed mechanical behavior via the computation of activation energy barriers is a topic of intense current research. Using dislocation nucleation from a crack tip as the reaction process, long-time multiscale molecular dynamics simulations show that the activation barrier can exhibit significant temperature dependence. Using an analytic model for the nucleation process and computing the relevant material properties (elastic constants and stacking fault energies), the temperature dependence is shown to arise primarily from the temperature dependence of the material parameters for both Al and Ni. After thermally activated emission of the first partial dislocation, there is then a competition between two other thermally activated processes: twinning and full dislocation emission. Because the activation barriers depend on temperature, this transition is more complex than usually envisioned. Simulations in Al reveal that a transition from twinning to full dislocation emission back to twinning occurs with increasing temperature, which is counter to traditional metallurgical wisdom. Temperature-dependent activation energies are thus essential to accurate understanding and prediction of those phenomena that control fracture and deformation in metals at realistic loading rates.

Perceived barriers, benefits, and motives for physical activity: two primary-care physical activity prescription programs.

Science.gov (United States)

Patel, Asmita; Schofield, Grant M; Kolt, Gregory S; Keogh J, W L

2013-01-01

This study examined whether perceived barriers, benefits, and motives for physical activity differed based on allocation to 2 different types of primary-care activity-prescription programs (pedometer-based vs. time-based Green Prescription). Eighty participants from the Healthy Steps study completed a questionnaire that assessed their perceived barriers, benefits, and motives for physical activity. Factor analysis was carried out to identify common themes of barriers, benefits, and motives for physical activity. Factor scores were then used to explore between-groups differences for perceived barriers, benefits, and motives based on group allocation and demographic variables. No significant differences were found in factor scores based on allocation. Demographic variables relating to the existence of chronic health conditions, weight status, and older age were found to significantly influence perceived barriers, benefits, and motives for physical activity. Findings suggest that the addition of a pedometer to the standard Green Prescription does not appear to increase perceived motives or benefits or decrease perceived barriers for physical activity in low-active older adults.

Estimates of fission barrier heights for neutron-deficient Po to Ra nuclei produced in fusion reactions

Directory of Open Access Journals (Sweden)

Sagaidak Roman

2017-01-01

Full Text Available The cross section data for fission and evaporation residue production in fusion reactions leading to nuclei from Po to Ra have been considered in a systematic way in the framework of the conventional barrier-passing (fusion model coupled with the statistical model. The cross section data obtained in very asymmetric projectile-target combinations can be described within these models rather well with the adjusted model parameters. In particular, one can scale and fix the macroscopic (liquid-drop fission barrier heights (FBHs for nuclei involved in the de-excitation of compound nuclei produced in the reactions. The macroscopic FBHs for nuclei from Po to Ra have been derived in the framework of such analysis and compared with the predictions of various theoretical models.

Perceived barriers to physical activity among Polish adolescents.

Science.gov (United States)

Jodkowska, Maria; Mazur, Joanna; Oblacińska, Anna

2015-01-01

To identify barriers to physical activity (PA) for adolescents according to the gender and age and examine the association between these barriers and youths' physical activity. 3346 students aged 10-16 years (1759 girls) took part in the cross-sectional, nationally representative study. For this paper the dataset was created from adolescents who reported perceived barriers to PA, N = 2300, (1259 girls), range 13-16 years. Barriers and physical activity (MVPA) were analysed for all participants, as well as by gender, age group and place of residence. Multiple regression analysis was used to examine the relationships between perceived barriers and physical inactivity for all and than separately for boys and girls. Lack of energy, lack of time and lack of support were three of the five barriers reported by more than 40% of adolescents, statistically more likely by girls than boys and older youth than younger. For boys - lack of time (OR = 2.56; CI = 1.66-3.96), lack of skills (OR = 2.35; CI = 1.94-3.95), lack of willpower (OR = 1.71, CI = 1.05-2.80) and lack of support (OR = 1.64, CI = 1.11-2.41) were the predictors contributing to low level of PA. For girls lack of skills (OR = 3.16, CI = 1.62-6.18), lack of energy (OR = 1.84, CI = 1.14-2.96), lack of support (OR = 1.64, CI = 1.07-2.54) and lack of time (OR = 1.61,CI = 1.00-2.60) were positively and statistically significant associated with physical inactivity. 1. Perceived barriers to physical activity among adolescents have strong negative impact on recommended PA level. For girls lack of skills is the strongest predictor of low PA, for boys - lack of time. 2. Identification more precisely barriers to physical activity among adolescents will enable to developed more effective interventions in high-risk populations.

Dynamics of {sup 58}Ni + {sup 54}Fe → {sup 112}Xe* reaction across the Coulomb barrier

Energy Technology Data Exchange (ETDEWEB)

Kaur, Manpreet; Sharma, Manoj K. [Thapar University, School of Physics and Materials Science, Patiala (India)

2014-03-15

The dynamical cluster-decay model (DCM) has been applied to study the decay of the {sup 112}Xe* compound nucleus formed in the massive heavy-ion reaction {sup 58}Ni + {sup 54}Fe at energies across the Coulomb barrier with E{sub c.m.} ∼ 85-110 MeV. The calculations are done for spherical fragmentation as well as by including deformation and orientation degrees of freedom of the decaying fragments. DCM-based cross sections give a nice description of the experimental fusion excitation function σ{sub ER}, within one parameter fitting, the neck length parameter (ΔR), whose value remains within the range of nuclear proximity interaction. The barrier height corresponding to the neck length parameter brings into the picture the barrier modification which enables us to address the data particularly at below barrier energies. The role of excitation energy (or temperature), deformations, orientations, angular momentum and diffuseness parameter is investigated to understand the dynamics of the {sup 58}Ni + {sup 54}Fe reaction. Finally the N/Z dependence of the fragmentation structure of different compound systems formed via {sup 58}Ni beam (projectile) is explored. (orig.)

Student Research in Rocket and Plume-Reaction Kinetics

National Research Council Canada - National Science Library

Fontijn, Arthur

1998-01-01

Semi-empirical configuration interaction (SECI) theory has been extended to predict activation barriers for combustion reactions of boron group halide oxidation reactions, Good agreement with experiments has been obtained...

Beyond mean-field approach to heavy-ion reactions around the Coulomb barrier

Directory of Open Access Journals (Sweden)

Ayik Sakir

2011-10-01

Full Text Available Dissipation and fluctuations of one-body observables in heavy-ion reactions around the Coulomb barrier are investigated with a microscopic stochastic mean-field approach. By projecting the stochastic meanfield dynamics on a suitable collective path, transport coefficients associated with the relative distance between colliding nuclei and a fragment mass are extracted. Although microscopic mean-field approach is know to underestimate the variance of fragment mass distribution, the description of the variance is much improved by the stochastic mean-field method. While fluctuations are consistent with the empirical (semiclassical analysis of the experimental data, concerning mean values of macroscopic variables the semiclassical description breaks down below the Coulomb barrier.

Measuring Perceived Barriers to Physical Activity in Adolescents.

Science.gov (United States)

Gunnell, Katie E; Brunet, Jennifer; Wing, Erin K; Bélanger, Mathieu

2015-05-01

Perceived barriers to moderate-to-vigorous physical activity (PA) may contribute to the low rates of moderate-to-vigorous PA in adolescents. We examined the psychometric properties of scores from the perceived barriers to moderate-to-vigorous PA scale (PB-MVPA) by examining composite reliability and validity evidence based on the internal structure of the PB-MVPA and relations with other variables. This study was a cross-sectional analysis of data collected in 2013 from adolescents (N = 507; Mage = 12.40, SD = .62) via self-report scales. Using exploratory and confirmatory factor analyses, we found that perceived barriers were best represented as two factors representing internal (e.g., "I am not interested in physical activity") and external (e.g., "I need equipment I don't have") dimensions. Composite reliability was over .80. Using multiple regression to examine the relationship between perceived barriers and moderate-to-vigorous PA, we found that perceived internal barriers were inversely related to moderate-to-vigorous PA (β = -.32, p barriers (p > .26). The PB-MVPA scale demonstrated evidence of score reliability and validity. To improve the understanding of the impact of perceived barriers on moderate-to- vigorous PA in adolescents, researchers should examine internal and external barriers separately.

Coupled-channel calculation for cross section of fusion and barrier distribution of {}^{16,17,18}O + {}^{16}O reactions

Science.gov (United States)

Fereidonnejad, R.; Sadeghi, H.; Ghambari, M.

2018-03-01

In this work, the effect of multi-phonon excitation on heavy-ion fusion reactions has been studied and fusion barrier distributions of energy intervals near and below the Coulomb barrier have been studied for 16,17,18O + 16O reactions. The structure and deformation of nuclear projectiles have been studied. Given the adaptation of computations to experimental data, our calculations predict the behavior of reactions in intervals of energy in which experimental measurements are not available. In addition the S-factor for these reactions has been calculated. The results showed that the structure and deformation of a nuclear projectile are important factors. The S-factor, obtained in the coupled-channel calculations for the {}^{16}O + {}^{16}O, {}^{17}O +{}^{16}O and {}^{18}O +{}^{16}O reactions, showed good agreement with the experimental data and had a maximum value at an energy near 5, 4.5 and 4 MeV, respectively.

Perceived benefits and barriers to leisure-time physical activity during pregnancy in previously inactive and active women.

Science.gov (United States)

Da Costa, Deborah; Ireland, Kierla

2013-01-01

This study compared perceived benefits and barriers to leisure-time physical activity during pregnancy among women who were insufficiently active or inactive before pregnancy. Eighty-two pregnant women completed questionnaires assessing leisure-time physical activity benefits/barriers, exercise self-efficacy, social support, depressed mood, pre-pregnancy and current physical activity and fatigue. Multivariable regression analyses identified factors associated with exercise benefits/barriers for the two pre-pregnancy leisure-time physical activity groups. Both pre-pregnancy leisure-time physical activity groups reported more benefits than barriers to exercise during pregnancy. Previously inactive women reported fewer perceived benefits and greater perceived barriers to leisure-time physical activity during pregnancy. Higher self-efficacy for exercise during pregnancy was significantly associated with greater benefits of leisure-time physical activity during pregnancy for both groups. Less family support for exercise and lower self-efficacy for exercise were significantly related to greater leisure-time physical activity barriers during pregnancy for previously inactive women. Lower self-efficacy for exercise, higher depressed mood scores, and younger age were associated with greater leisure-time physical activity barriers for active women. Findings suggest that the intensities of perceived leisure-time physical activity benefits and barriers during pregnancy differ for women, depending on their pre-pregnancy leisure-time physical activity status. Consideration of pre-pregnancy leisure-time physical activity status may thus be important when tailoring strategies to overcome barriers to promote initiation and maintenance of physical activity during pregnancy.

Circularly polarized antennas for active holographic imaging through barriers

Science.gov (United States)

McMakin, Douglas L [Richland, WA; Severtsen, Ronald H [Richland, WA; Lechelt, Wayne M [West Richland, WA; Prince, James M [Kennewick, WA

2011-07-26

Circularly-polarized antennas and their methods of use for active holographic imaging through barriers. The antennas are dielectrically loaded to optimally match the dielectric constant of the barrier through which images are to be produced. The dielectric loading helps to remove barrier-front surface reflections and to couple electromagnetic energy into the barrier.

Attempting to be active: Self-efficacy and barrier limitation differentiate activity levels of working mothers.

Science.gov (United States)

Gierc, Madelaine; Locke, Sean; Jung, Mary; Brawley, Lawrence

2016-07-01

Working mothers are less physically active than working women without children and mothers who do not work. The purpose of this study was to examine concurrent self-regulatory efficacy and barriers to physical activity in a sample of working mothers. Women completed a mixed-methods survey which included measures of physical activity, concurrent self-regulatory efficacy, and barriers. Sufficiently active women experienced significantly greater concurrent self-regulatory efficacy and significantly less barrier limitation and frequency. No significant group differences were found for age, domestic duties performed, and children's extracurricular activities. Thematic analysis of barriers revealed six themes of common and unique factors, including limited time and family activities. © The Author(s) 2014.

Nuclear reactions of the system 6 Li on 58 Ni near the Coulomb barrier

International Nuclear Information System (INIS)

Lizcano, D.; Aguilera, E.F.; Garcia M, H.; Martinez Q, E.

2004-01-01

Protons, alpha particles and deuterons coming from the reactions 6 Li + 58 Ni are detected to three different energy around the Coulomb barrier. The possible effects of the weakly bound character of the projectile are studied and the results are compared with previous data for the system 6 Li + 59 Co. (Author)

Activation measurements of α-induced reactions at sub-Coulomb energies

Energy Technology Data Exchange (ETDEWEB)

Scholz, Philipp; Dewald, Alfred; Heinze, Stefan; Mayer, Jan; Mueller-Gatermann, Claus; Netterdon, Lars; Zilges, Andreas [Institute for Nuclear Physics, University of Cologne (Germany); Endres, Anne [Institute for Applied Physics, Goethe University Frankfurt am Main (Germany)

2015-07-01

Network calculations of the γ process rely almost completely on theoretically predicted reaction rates within the scope of the Hauser-Feshbach Statistical Model. Especially the prediction of cross sections for (γ,α)-reactions at energies within or close to the astrophysically relevant energy window remains a problem due to the uncertainties in the underlying α-optical-model potentials. Although experimental values far above the Coulomb-barrier are well reproduced, commonly used α-optical potentials often fail to describe the trend at energies comparable to those at astrophysical sites of the γ process. Improvements of the adopted optical-model potentials are hampered by the lack of experimental cross sections at sub-Coulomb energies. In order to enlarge the experimental data base, cross sections of the {sup 187}Re(α,n) and {sup 108}Cd(α,n) reactions were investigated using the activation technique with the Cologne Clover Counting Setup. Besides recent experimental results, future plans for more sensitive cross-section studies applying Accelerator Mass Spectrometry using CologneAMS are presented.

Barriers to Leisure-Time Physical Activities in Individuals with Spinal Cord Injury.

Science.gov (United States)

Hwang, Eric J; Groves, Mary D; Sanchez, Jacqueline N; Hudson, Cassandra E; Jao, Rachel G; Kroll, Meghan E

2016-07-01

This study investigated the personal, environmental, and activity barriers to leisure-time physical activities (LTPAs) among individuals with spinal cord injury (SCI). A survey instrument was administered to 85 participants with SCI. Personal barriers to LTPAs included issues involving motivation, pain, scheduling, and financial resources. Environmental barriers marked the issues regarding availability and accessibility to specialized programs, activities, and professional services. Activity barriers included limitations in equipment, training, and personal skills required by the selected activities. Significant negative correlations were found between these barriers and the levels of physical activity and satisfaction with physical activity. While working with clients with SCI, occupational therapists should identify those LTPA barriers and possible solutions in order to establish individualized action plans for enhancing participation in LTPAs.

Barrier-beliefs about physical activity in active and inactive adults : an explorative study

NARCIS (Netherlands)

Bouma, Adrie

2018-01-01

Objectives: Perceived barriers are often a reason why people do not start physical activity or relapse to inactivity. From a psychological perspective, barriers can be seen as beliefs about what is obstructing people’s behavior. To understand inactivity and relapse from physical activity, this study

Barriers to Physical Activity in East Harlem, New York

Directory of Open Access Journals (Sweden)

Ashley M. Fox

2012-01-01

Full Text Available Background. East Harlem is an epicenter of the intertwining epidemics of obesity and diabetes in New York. Physical activity is thought to prevent and control a number of chronic illnesses, including diabetes, both independently and through weight control. Using data from a survey collected on adult (age 18+ residents of East Harlem, this study evaluated whether perceptions of safety and community-identified barriers were associated with lower levels of physical activity in a diverse sample. Methods. We surveyed 300 adults in a 2-census tract area of East Harlem and took measurements of height and weight. Physical activity was measured in two ways: respondents were classified as having met the weekly recommended target of 2.5 hours of moderate physical activity (walking per week (or not and reporting having engaged in at least one recreational physical activity (or not. Perceived barriers were assessed through five items developed by a community advisory board and perceptions of neighborhood safety were measured through an adapted 7-item scale. Two multivariate logistic regression models with perceived barriers and concerns about neighborhood safety were modeled separately as predictors of engaging in recommended levels of exercise and recreational physical activity, controlling for respondent weight and sociodemographic characteristics. Results. The most commonly reported perceived barriers to physical activity identified by nearly half of the sample were being too tired or having little energy followed by pain with exertion and lack of time. Multivariate regression found that individuals who endorsed a greater number of perceived barriers were less likely to report having met their weekly recommended levels of physical activity and less likely to engage in recreational physical activity controlling for covariates. Concerns about neighborhood safety, though prevalent, were not associated with physical activity levels. Conclusions. Although

Barriers for recess physical activity: a gender specific qualitative focus group exploration.

Science.gov (United States)

Pawlowski, Charlotte Skau; Tjørnhøj-Thomsen, Tine; Schipperijn, Jasper; Troelsen, Jens

2014-06-23

Many children, in particular girls, do not reach the recommended amount of daily physical activity. School recess provides an opportunity for both boys and girls to be physically active, but barriers to recess physical activity are not well understood. This study explores gender differences in children's perceptions of barriers to recess physical activity. Based on the socio-ecological model four types of environmental barriers were distinguished: natural, social, physical and organizational environment. Data were collected through 17 focus groups (at 17 different schools) with in total 111 children (53 boys) from fourth grade, with a mean age of 10.4 years. The focus groups included an open group discussion, go-along group interviews, and a gender segregated post-it note activity. A content analysis of the post-it notes was used to rank the children's perceived barriers. This was verified by a thematic analysis of transcripts from the open discussions and go-along interviews. The most frequently identified barriers for both boys and girls were weather, conflicts, lack of space, lack of play facilities and a newly-found barrier, use of electronic devices. While boys and girls identified the same barriers, there were both inter- and intra-gender differences in the perception of these barriers. Weather was a barrier for all children, apart from the most active boys. Conflicts were perceived as a barrier particularly by those boys who played ballgames. Girls said they would like to have more secluded areas added to the school playground, even in large schoolyards where lack of space was not a barrier. This aligned with girls' requests for more "hanging-out" facilities, whereas boys primarily wanted activity promoting facilities. Based on the results from this study, we recommend promoting recess physical activity through a combination of actions, addressing barriers within the natural, social, physical and organizational environment.

Structure, activity, and stability of platinum alloys as catalysts for the oxygen reduction reaction

DEFF Research Database (Denmark)

Vej-Hansen, Ulrik Grønbjerg

In this thesis I present our work on theoretical modelling of platinum alloys as catalysts for the Oxygen Reduction Reaction (ORR). The losses associated with the kinetics of the ORR is the main bottleneck in low-temperature fuel cells for transport applications, and more active catalysts...... are essential for wide-spread use of this technology. platinum alloys have shown great promise as more active catalysts, which are still stable under reaction conditions. We have investigated these systems on multiple scales, using either Density Functional Theory (DFT) or Effective Medium Theory (EMT......), depending on the length and time scales involved. Using DFT, we show how diffusion barriers in transition metal alloys in the L12 structure depend on the alloying energy, supporting the assumption that an intrinsically more stable alloy is also more stable towards diffusion-related degradation...

Universal trend for heavy-ion total reaction cross sections at energies above the Coulomb barrier

International Nuclear Information System (INIS)

Tavares, O.A.P.; Medeiros, E.L.; Morcelle, V.

2010-06-01

Heavy-ion total reaction cross section measurements for more than one thousand one hundred reaction cases covering 61 target nuclei in the range 6 Li- 238 U, and 158 projectile nuclei from 2 H up to 84 Kr (mostly exotic ones) have been analysed in a systematic way by using an empirical, three-parameter formula which is applicable to cases for projectile kinetic energies above the Coulomb barrier. The analysis has shown that the average total nuclear binding energy per nucleon of the interacting nuclei and their radii are the chief quantities which describe the cross section patterns. A great number of cross section data (87%) has been quite satisfactorily reproduced by the proposed formula, therefore total reaction cross section predictions for new, not yet experimentally investigated reaction cases can be obtained within 25 percent (or much less) of uncertainty (author)

Physical activity barriers and facilitators among working mothers and fathers.

Science.gov (United States)

Mailey, Emily L; Huberty, Jennifer; Dinkel, Danae; McAuley, Edward

2014-06-27

The transition to parenthood is consistently associated with declines in physical activity. In particular, working parents are at risk for inactivity, but research exploring physical activity barriers and facilitators in this population has been scarce. The purpose of this study was to qualitatively examine perceptions of physical activity among working parents. Working mothers (n = 13) and fathers (n = 12) were recruited to participate in one of four focus group sessions and discuss physical activity barriers and facilitators. Data were analyzed using immersion/crystallization in NVivo 10. Major themes for barriers included family responsibilities, guilt, lack of support, scheduling constraints, and work. Major themes for facilitators included being active with children or during children's activities, being a role model for children, making time/prioritizing, benefits to health and family, and having support available. Several gender differences emerged within each theme, but overall both mothers and fathers reported their priorities had shifted to focus on family after becoming parents, and those who were fitting in physical activity had developed strategies that allowed them to balance their household and occupational responsibilities. The results of this study suggest working mothers and fathers report similar physical activity barriers and facilitators and would benefit from interventions that teach strategies for overcoming barriers and prioritizing physical activity amidst the demands of parenthood. Future interventions might consider targeting mothers and fathers in tandem to create an optimally supportive environment in the home.

Barriers to involvement in physical activities of persons with mental illness.

Science.gov (United States)

Shor, Ron; Shalev, Anat

2016-03-01

Participating in physical activities could be essential for reducing the multiple risk factors for health problems that persons with severe mental illness (SMI) may suffer. However, people with SMI are significantly less active than the general population. To develop knowledge about factors related to the perceived barriers hindering this population's participation in physical activities and the benefits this participation would have, a study was conducted in Israel with 86 people with mental illness living in community mental health facilities prior to their participation in a health promotion program. A mixed method was implemented and included: a scale designed to measure participants' perceptions of the barriers to and benefits of involvement in physical activities; instruments focusing on bio-psycho-social factors that may affect the level of barriers experienced; and personal interviews. The findings revealed high ranking for accessibility barriers hindering the participation in physical activities. Bio-psycho-social factors stemming from the participants' mental health, such as level of depression, were correlated with higher ranking of accessibility barriers. Bio-psycho-social factors reflecting positive mental health and health, such as positive appraisal of body weight, were correlated with lower ranking of accessibility barriers. Other barriers may include organizational and broader systemic barriers in the mental health facilities where the participants reside. These findings illuminate the need to consider the unique challenges that persons with mental illness may face in any attempt to advance their involvement in physical activity. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Quantum chemical modeling of zeolite-catalyzed methylation reactions: toward chemical accuracy for barriers.

Science.gov (United States)

Svelle, Stian; Tuma, Christian; Rozanska, Xavier; Kerber, Torsten; Sauer, Joachim

2009-01-21

The methylation of ethene, propene, and t-2-butene by methanol over the acidic microporous H-ZSM-5 catalyst has been investigated by a range of computational methods. Density functional theory (DFT) with periodic boundary conditions (PBE functional) fails to describe the experimentally determined decrease of apparent energy barriers with the alkene size due to inadequate description of dispersion forces. Adding a damped dispersion term expressed as a parametrized sum over atom pair C(6) contributions leads to uniformly underestimated barriers due to self-interaction errors. A hybrid MP2:DFT scheme is presented that combines MP2 energy calculations on a series of cluster models of increasing size with periodic DFT calculations, which allows extrapolation to the periodic MP2 limit. Additionally, errors caused by the use of finite basis sets, contributions of higher order correlation effects, zero-point vibrational energy, and thermal contributions to the enthalpy were evaluated and added to the "periodic" MP2 estimate. This multistep approach leads to enthalpy barriers at 623 K of 104, 77, and 48 kJ/mol for ethene, propene, and t-2-butene, respectively, which deviate from the experimentally measured values by 0, +13, and +8 kJ/mol. Hence, enthalpy barriers can be calculated with near chemical accuracy, which constitutes significant progress in the quantum chemical modeling of reactions in heterogeneous catalysis in general and microporous zeolites in particular.

Barriers for recess physical activity: a gender specific qualitative focus group exploration

DEFF Research Database (Denmark)

Pawlowski, Charlotte Skau; Tjørnhøj-Thomsen, Tine; Schipperijn, Jasper

Background: Many children, in particular girls, do not reach the recommended amount of daily physical activity. School recess provides an opportunity for both boys and girls to be physically active, but barriers to recess physical activity are not well understood. This study explores gender...... (53 boys) from fourth grade, with a mean age of 10.4 years. The focus groups included an open group discussion, go-along group interviews, and a gender segregated post-it note activity. A content analysis of the post-it notes was used to prioritize the children´s perceived barriers. This was verified...... barriers, there were both inter- and intra-gender differences in the children´s perceptions of these barriers. Weather was a barrier for all children, apart from the most active boys. Conflicts were perceived as a barrier particularly for those boys who played ballgames. Girls said they would like to have...

Role of hexadecapole deformation of projectile 28Si in heavy-ion fusion reactions near the Coulomb barrier

Science.gov (United States)

Kaur, Gurpreet; Hagino, K.; Rowley, N.

2018-06-01

The vast knowledge regarding the strong influence of quadrupole deformation β2 of colliding nuclei in heavy-ion sub-barrier fusion reactions inspires a desire to quest the sensitivity of fusion dynamics to higher order deformations, such as β4 and β6 deformations. However, such studies have rarely been carried out, especially for deformation of projectile nuclei. In this article, we investigated the role of β4 of the projectile nucleus in the fusion of the 28Si+92Zr system. We demonstrated that the fusion barrier distribution is sensitive to the sign and value of the β4 parameter of the projectile, 28Si, and confirmed that the 28Si nucleus has a large positive β4. This study opens an indirect way to estimate deformation parameters of radioactive nuclei using fusion reactions, which is otherwise difficult because of experimental constraints.

Theoretical investigation of molecular hydrogen reactions with active centres in B6H5- and AlB6H5- clusters

International Nuclear Information System (INIS)

Mebel', A.M.; Charkin, O.P.

1991-01-01

Nonempirical calculations of sections of potential surface (PS) along the shortest way of reaction of hydrogen interaction with different active centres in AlB 5 H 5 - cluster were conducted. Mechanisms of reactions of valent-saturated hydrides (BH, AlH) and clusters (B 6 H 5 - , AlB 5 H 5 - ) with molecular hydrogen are correlated. Qualitative model enabling to form an opinion about the presence or the absence of barrier on PS of the shortest way of reactions of breaking σ-bond of H-H type on the active centre of cluster, is suggested. The model is based on analysis of the character of canonical MO reagents and products

Barriers to activity and participation for stroke survivors in rural China.

Science.gov (United States)

Zhang, Lifang; Yan, Tiebin; You, Liming; Li, Kun

2015-07-01

To investigate environmental barriers reported by stroke survivors in the rural areas of China and to determine the impact of environmental barriers on activity and participation relative to demographic characteristics and body functioning. Cross-sectional survey. Structured interviews in the participants' homes. Community-dwelling stroke survivors in the rural areas of China (N=639). Not applicable. Activity and participation (Chinese version of the World Health Organization Disability Assessment Schedule 2.0), environmental barriers (Craig Hospital Inventory of Environmental Factors), neurological function (Canadian Neurological Scale), cognitive function (Abbreviated Mental Test), and depression (6-item Hamilton Rating Scale for Depression). Physical/structural barriers are the major impediment to activity and participation for these participants (odds ratio, 1.86 and 1.99 for activity and participation, respectively; Penvironmental barriers to be decreased and eliminated first. Copyright © 2015 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

Universal trend for heavy-ion total reaction cross sections at energies above the Coulomb barrier

Energy Technology Data Exchange (ETDEWEB)

Tavares, O.A.P.; Medeiros, E.L., E-mail: emil@cbpf.b [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil); Morcelle, V. [Universidade de Sao Paulo (IF/USP), SP (Brazil). Inst. de Fisica

2010-06-15

Heavy-ion total reaction cross section measurements for more than one thousand one hundred reaction cases covering 61 target nuclei in the range {sup 6}Li-{sup 238}U, and 158 projectile nuclei from {sup 2}H up to {sup 84}Kr (mostly exotic ones) have been analysed in a systematic way by using an empirical, three-parameter formula which is applicable to cases for projectile kinetic energies above the Coulomb barrier. The analysis has shown that the average total nuclear binding energy per nucleon of the interacting nuclei and their radii are the chief quantities which describe the cross section patterns. A great number of cross section data (87%) has been quite satisfactorily reproduced by the proposed formula, therefore total reaction cross section predictions for new, not yet experimentally investigated reaction cases can be obtained within 25 percent (or much less) of uncertainty (author)

A cluster expansion model for predicting activation barrier of atomic processes

International Nuclear Information System (INIS)

Rehman, Tafizur; Jaipal, M.; Chatterjee, Abhijit

2013-01-01

We introduce a procedure based on cluster expansion models for predicting the activation barrier of atomic processes encountered while studying the dynamics of a material system using the kinetic Monte Carlo (KMC) method. Starting with an interatomic potential description, a mathematical derivation is presented to show that the local environment dependence of the activation barrier can be captured using cluster interaction models. Next, we develop a systematic procedure for training the cluster interaction model on-the-fly, which involves: (i) obtaining activation barriers for handful local environments using nudged elastic band (NEB) calculations, (ii) identifying the local environment by analyzing the NEB results, and (iii) estimating the cluster interaction model parameters from the activation barrier data. Once a cluster expansion model has been trained, it is used to predict activation barriers without requiring any additional NEB calculations. Numerical studies are performed to validate the cluster expansion model by studying hop processes in Ag/Ag(100). We show that the use of cluster expansion model with KMC enables efficient generation of an accurate process rate catalog

Reaction mechanisms in collisions induced by $^{8}$B beam close to the barrier

CERN Multimedia

The aim of the proposed experiment is to investigate the reaction dynamics of proton-halo induced collisions at energies around the Coulomb barrier where coupling to continuum effects are expected to be important. We propose to measure the $^{8}$B + $^{64}$Zn elastic scattering angular distribution together with the measurement, for the first time, of p - $^{7}$Be coincidences coming from transfer and/or break-up of $^{8}$B. The latter will allow a better understanding of the relative contribution of elastic $\\textit{vs}$ non-elastic break-up in reactions induced by extremely weakly-bound nuclei. We believe that with the availability of the post accelerated $^{8}$B beam at REX-ISOLDE we will be able to collect for the first time high quality data for the study of such an important topic.

Reaction kinetics, reaction products and compressive strength of ternary activators activated slag designed by Taguchi method

NARCIS (Netherlands)

Yuan, B.; Yu, Q.L.; Brouwers, H.J.H.

2015-01-01

This study investigates the reaction kinetics, the reaction products and the compressive strength of slag activated by ternary activators, namely waterglass, sodium hydroxide and sodium carbonate. Nine mixtures are designed by the Taguchi method considering the factors of sodium carbonate content

Motivational readiness for active commuting by university students: incentives and barriers.

Science.gov (United States)

Cole, Rachel; Leslie, Eva; Donald, Maria; Cerin, Ester; Neller, Anne; Owen, Neville

2008-12-01

Walking for transport can contribute significantly to health-enhancing physical activity. We examined the associations of stages of motivational readiness for active transport with perceived barriers and incentives to walking to and from university among students. Mail-back surveys were completed by 781 students in a regional university in south-east Queensland. They identified one of eight options on motivational readiness for active commuting, which were then classified as: pre-contemplation; contemplation-preparation; or, action-maintenance. Open-ended questions were used to identify relevant barriers and incentives. Logistic regressions were used to examine the barriers and incentives that distinguished between those at different stages of motivational readiness. Barriers most frequently reported were long travel distances, inconvenience and time constraints. Incentives most frequently reported were shorter travel distance, having more time, supportive infrastructure and better security. Those not considering active commuting (pre-contemplation) were significantly more likely to report shorter travel distance as an incentive compared to those in contemplation-preparation. Those in contemplation-preparation were significantly more likely to report lack of motivation, inadequate infrastructure, shorter travel distance and inconvenience as barriers; and, having more time, supportive infrastructure, social support and incentive programs as encouragement. Different barriers and incentives to walking to or from university exist for students in the different stages of motivational readiness for active commuting. Interventions targeted specifically to stage of motivational readiness may be potentially helpful in increasing activity levels, through active transport.

Understanding Motivators and Barriers to Physical Activity

Science.gov (United States)

Patay, Mary E.; Patton, Kevin; Parker, Melissa; Fahey, Kathleen; Sinclair, Christina

2015-01-01

The purpose of this study was to understand the factors that influence physical activity among year-round residents in an isolated summer resort community. Specifically, we explored the personal, environmental, social, and culture-specific perceived motivators and barriers to physical activity. Participants were formally interviewed about their…

Morphological impact on the reaction kinetics of size-selected cobalt oxide nanoparticles

International Nuclear Information System (INIS)

Bartling, Stephan; Meiwes-Broer, Karl-Heinz; Barke, Ingo; Pohl, Marga-Martina

2015-01-01

Apart from large surface areas, low activation energies are essential for efficient reactions, particularly in heterogeneous catalysis. Here, we show that not only the size of nanoparticles but also their detailed morphology can crucially affect reaction kinetics, as demonstrated for mass-selected, soft-landed, and oxidized cobalt clusters in a 6 nm to 18 nm size range. The method of reflection high-energy electron diffraction is extended to the quantitative determination of particle activation energies which is applied for repeated oxidation and reduction cycles at the same particles. We find unexpectedly small activation barriers for the reduction reaction of the largest particles studied, despite generally increasing barriers for growing sizes. We attribute these observations to the interplay of reaction-specific material transport with a size-dependent inner particle morphology

Preferences for and Barriers to Formal and Informal Athletic Training Continuing Education Activities

Science.gov (United States)

Armstrong, Kirk J.; Weidner, Thomas G.

2011-01-01

Context: Our previous research determined the frequency of participation and perceived effect of formal and informal continuing education (CE) activities. However, actual preferences for and barriers to CE must be characterized. Objective: To determine the types of formal and informal CE activities preferred by athletic trainers (ATs) and barriers to their participation in these activities. Design: Cross-sectional study. Setting: Athletic training practice settings. Patients or Other Participants: Of a geographically stratified random sample of 1000 ATs, 427 ATs (42.7%) completed the survey. Main Outcome Measure(s): As part of a larger study, the Survey of Formal and Informal Athletic Training Continuing Education Activities (FIATCEA) was developed and administered electronically. The FIATCEA consists of demographic characteristics and Likert scale items (1 = strongly disagree, 5 = strongly agree) about preferred CE activities and barriers to these activities. Internal consistency of survey items, as determined by Cronbach α, was 0.638 for preferred CE activities and 0.860 for barriers to these activities. Descriptive statistics were computed for all items. Differences between respondent demographic characteristics and preferred CE activities and barriers to these activities were determined via analysis of variance and dependent t tests. The α level was set at .05. Results: Hands-on clinical workshops and professional networking were the preferred formal and informal CE activities, respectively. The most frequently reported barriers to formal CE were the cost of attending and travel distance, whereas the most frequently reported barriers to informal CE were personal and job-specific factors. Differences were noted between both the cost of CE and travel distance to CE and all other barriers to CE participation (F1,411 = 233.54, P formal CE activities. The same barriers (eg, cost, travel distance) to formal CE appeared to be universal to all ATs. Informal CE was

Does weight status influence perceptions of physical activity barriers among African-American women?

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Genkinger, Jeanine M; Jehn, Megan L; Sapun, Marcella; Mabry, Iris; Young, Deborah Rohm

2006-01-01

Many African-American women fail to participate in regular physical activity. Weight status may influence physical activity barriers. This study examined the frequency and type of barriers. Participants in this study were enrolled in Project EXE-L (Exercising Ladies Excel), a six-month, church-based, randomized trial of moderate-intensity physical activity based in Baltimore city and county in Maryland. Participants were composed of African-American women who attended one of the participating churches, had friends who were church members, or who lived in neighborhoods surrounding one of the churches. Individuals who were between the ages of 25 and 70 years, were not regularly physically active (defined as not engaging in moderate-intensity activity more than three times per week), and were able to participate in moderate-intensity activity met eligibility criteria to participate in the trial. Barriers to physical activity were evaluated with the Steinhardt/Dishman Barriers for Habitual Physical Activity Scale at baseline. One hundred twenty women were classified as normal weight (body mass index [BMI]: or = 30 kg/m2). Obese participants were more likely to report "lack of motivation" as a barrier compared with normal-weight participants (63% vs 31%). Normal-weight and overweight participants were more likely to report no barriers compared with the obese (31%, 0%, 5%, respectively, P<.05). Barriers for African-American women may vary by BMI status. By defining these unique barriers, effective physical activity interventions can be developed.

What we have learned so far on reactions and scattering with weakly bound nuclei at near barrier energies

International Nuclear Information System (INIS)

Gomes, P.R.S.

2011-01-01

Reactions involving weakly bound nuclei, especially halo nuclei, at near barrier energies, are an important subject not yet fully understood. Due to the low threshold energy for breakup, this process is particularly important and may affect significantly the fusion process and elastic scattering. In this talk I will show the systematic of results so far available in this field, concerning static and dynamical effects of halo and breakup on fusion and total reaction cross sections, the energy dependence of the optical potential on the elastic scattering and coupling effects on quasi-elastic scattering barrier distributions involving weakly bound nuclei, both stable and radioactive. The data to be discussed are new data from our group and from the literature, together with some older data. I will also present some experimental challenges for the development of this field. (author)

Barriers associated with reduced physical activity in COPD patients.

Science.gov (United States)

Amorim, Priscila Batista; Stelmach, Rafael; Carvalho, Celso Ricardo Fernandes; Fernandes, Frederico Leon Arrabal; Carvalho-Pinto, Regina Maria; Cukier, Alberto

2014-10-01

To evaluate the ability of COPD patients to perform activities of daily living (ADL); to identify barriers that prevent these individuals from performing ADL; and to correlate those barriers with dyspnea severity, six-minute walk test (6MWT), and an ADL limitation score. In COPD patients and healthy, age-matched controls, the number of steps, the distance walked, and walking time were recorded with a triaxial accelerometer, for seven consecutive days. A questionnaire regarding perceived barriers and the London Chest Activity of Daily Living (LCADL) scale were used in order to identify the factors that prevent the performance of ADL. The severity of dyspnea was assessed with two scales, whereas submaximal exercise capacity was determined on the basis of the 6MWT. We evaluated 40 COPD patients and 40 controls. In comparison with the control values, the mean walk time was significantly shorter for COPD patients (68.5 ± 25.8 min/day vs. 105.2 ± 49.4 min/day; p barriers to performing ADL were lack of infrastructure, social influences, and lack of willpower. The 6MWT distance correlated with the results obtained with the accelerometer but not with the LCADL scale results. Patients with COPD are less active than are healthy adults of a comparable age. Physical inactivity and the barriers to performing ADL have immediate implications for clinical practice, calling for early intervention measures.

BARRIERS TO PHYSICAL ACTIVITY IN THE ELDERLY

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Paulo Matias

2015-04-01

Full Text Available The population awareness of the physical exercise’s benefits is widely diffused. These benefits are particularly important in the elderly because, with increasing age, there is a decline of the musculoskeletal system and the maximum oxygen consumption which reduces the functional fitness of the elderly and can often lead to a significant decline in the quality of life. Despite this awareness, a large part of the population remains sedentary. It is important to know what the barriers are, so they can be circumvented in order to increase the engagement of the elderly population in existing physical activity programs.Objectives: This study aims to identify some of the personal, behavioral and environmental barriers that prevent older adults to be physically active.

Study of the (3He,d) reactions on 58Ni, 60Ni and 56Fe near the Coulomb barrier

International Nuclear Information System (INIS)

Baghdadi, A.; Seltz, R.; Magnac-Valette, D.; Bonneaud, G.; Gerardin, C.

1975-01-01

Using spectroscopic information gained by earlier measurements of the proton bound states populated by stripping reactions, ( 3 He,d) reactions on 58 Ni, 60 Ni and 56 Fe targets are studied at energies near the Coulomb barrier and evaluation is made of the vertex function 3 He>. This value is then used to determine spectroscopic factors for low-lying states in 57 Co [fr

Investigating the status and barriers of science laboratory activities ...

African Journals Online (AJOL)

This study aims at investigating the barriers encountered by science teachers in laboratory activities in Rwandan teacher training colleges (TTCs) using questionnaires and interviews. The results confirmed that teachers face barriers like time limitation, material scarcity and lack of improvising skills in their everyday science ...

Active commuting: prevalence, barriers, and associated variables.

Science.gov (United States)

Silva, Kelly Samara; Vasques, Daniel Giordani; Martins, Caroline de Oliveira; Williams, Laura Ashley; Lopes, Adair S

2011-08-01

Research has demonstrated that adolescents who actively commute have higher levels of physical activity (PA), which have declined precipitously over the past 30 years. The purpose of this study was to describe the prevalence of active commuting to school; and to identify barriers associated with active commuting. A cross-sectional study was conducted with 1672 students (46.8% boys and 53.2% girls) from 11 to 17 years of age in Caxias do Sul/RS, Brazil. The students were asked to answer questionnaires about active transport, PA, and sedentary behaviors. They also completed a cardiovascular fitness test and body composition measurements. The study used a multivariate Poisson regression analysis. A total of 62.5% of students were observed to actively commute and the prevalence ratio (PR) of not actively commuting was associated with the type of school (Private: 2.41; 1.47, 3.95) and the time spent on commuting (>20 min: 1.93; 1.23, 3.03). The associated barriers to passive commuting were distance (3.02; 1.95, 4.71), crime/danger (2.65; 1.82, 3.85), and traffic (1.75; 1.19, 2.58). This study showed that environmental variables were strongly associated with active commuting. However, no alterations in body composition or other behavioral variables were observed after adjustment.

Are barriers to physical activity similar for adults with and without abnormal glucose metabolism?

Science.gov (United States)

Hume, Clare; Dunstan, David; Salmon, Jo; Healy, Genevieve; Andrianopoulos, Nick; Owen, Neville

2010-01-01

The purpose of this study was to examine perceived barriers to physical activity among adults with and without abnormal glucose metabolism (AGM), and whether barriers varied according to physical activity status. The 1999 to 2000 Australian Diabetes, Obesity, and Lifestyle Study (AusDiab) was a population-based cross-sectional study among adults aged > or =25 years. AGM was identified through an oral glucose tolerance test. The previous week's physical activity and individual, social, and environmental barriers to physical activity were self-reported. Logistic regression analyses examined differences in barriers to physical activity between those with and without AGM, and for those with and without AGM who did and did not meet the minimum recommendation of 150 minutes/week of moderate-to-vigorous intensity physical activity. Of the 7088 participants (47.5 +/- 12.7 years; 46% male), 18.5% had AGM. Approximately 47.5% of those with AGM met the physical activity recommendation, compared to 54.7% of those without AGM (P barriers to physical activity included lack of time, other priorities, and being tired. Following adjustment for sociodemographic and behavioral factors, there were few differences in barriers to physical activity between those with and without AGM, even after stratifying according to physical activity. Adults with AGM report similar barriers to physical activity, as do those without AGM. Programs for those with AGM can therefore focus on the known generic adult-reported barriers to physical activity.

Barriers to physical activity in older adults in Germany: a cross-sectional study

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Moschny Anna

2011-11-01

Full Text Available Abstract Background Data on barriers to physical activity in older adults in Germany are scarce. The aim of this study was to analyse barriers to physical activity in a cohort of older adults, allowing comparisons between men and women, and age groups. Methods 1,937 older adults with a median age of 77 (range 72-93 years (53.3% female took part in the 7-year follow-up telephone interviews of the getABI cohort. Participants who stated that they did not get enough physical activity were surveyed with respect to barriers to physical activity. Barriers were analysed for all respondents, as well as by sex and age group for cases with complete data. Multivariate logistic regression analysis was performed to evaluate differences between sexes and age groups. The level of significance (alpha Results 1,607 (83.0% participants stated that they were sufficiently physically active. 286 participants rated their physical activity as insufficient and responded to questions on barriers to physical activity completely. The three most frequently cited barriers were poor health (57.7%, lack of company (43.0%, and lack of interest (36.7%. Lack of opportunities for sports or leisure activities (30.3% vs. 15.6%, and lack of transport (29.0% vs. 7.1% were more frequently stated by female respondents than male respondents. These differences between men and women were significant (p = .003; p Conclusions The present study provides relevant data on barriers to physical activity in older adults. By revealing appreciable differences between men and women, and age groups, this study has implications for efforts to increase older adults' physical activity. Promotion and intervention strategies should consider the barriers and tailor measures to the specific needs of older adults in order to reduce their constraints to physical activity.

Fusion barriers in heavy ion collisions

International Nuclear Information System (INIS)

Zhu Long; Su Jun; Xie Wenjie; Guo Chenchen; Zhang Donghong; Zhang Fengshou

2014-01-01

Study of fusion barrier is very important for people to better understand fusion reactions. In this paper the Improved Isospin-dependent Quantum Molecular Dynamics (ImIQMD) model is introduced firstly. Then the shell correction effects, energy dependence, isospin effects and orientation effects of fusion barrier are studied. The fusion barriers for the fusion reactions "4"0Ca + "4"0Ca, "4"8Ca + "2"0"8Pb, "4"8Ca + "2"0"4Pb and "1"6O + "1"5"4Sm are extracted. The negative shell correction energies lower potential barriers of a certain reaction. A complex phenomenon of energy dependence is observed. It is also found that incident energy dependence of the barrier radius and barrier height shows opposite behaviors. The Coulomb potential shows weak energy dependence when distance of two colliding nuclei is lower than the touching distance. The isospin effects of the potential barrier are investigated. The orientation effects of the potential barrier are also discussed for the system "1"6O + "1"5"4Sm. (authors)

Sensitivity of fusion and quasi-elastic barrier distributions of {sub 16}O+{sub 144}Sm reaction on the coupling radius parameter

Energy Technology Data Exchange (ETDEWEB)

Zamrun, Muhammad; Usman, Ida; Variani, Viska Inda [Department of Physics, Haluoleo University, Kendari, Sulawesi Tengagra, 93232 (Indonesia); Kassim, Hasan Abu [Department of Physics, University of Malaya, 50603 Kuala Lumpur (Malaysia)

2014-03-05

We study the heavy-ion collision at sub-barrier energies of {sub 16}O+{sub 144}Sm system using full order coupled-channels formalism. We especially investigate the sensitivity of fusion and quasi-elastic barrier distributions for this system on the coupling radius parameter. We found that the coupled-channels calculations of the fusion and the quasi-elastic barrier distributions are sensitive to the coupling radius for this reaction in contrast to the fusion and quasi-elastic cross section. Our study indicates that the larger coupling radius, i.e., r{sub coup}=1.20, is required by the experimental quasi-elastic barrier distribution. However, the experimental fusion barrier distribution compulsory the small value, i.e., r{sub coup}=1.06.

Reaction dynamics studies for the system 7Be + 208Pb at Coulomb barrier energies

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Mazzocco M.

2017-01-01

Full Text Available The scattering process of the Radioactive Ion Beam 7Be from a 208Pb target was measured at three near-barrier energies. The quasi-elastic angular distributions were analyzed within the framework of the optical model to extract the reaction cross sections. The results are compared with those obtained for the reactions induced by the mirror projectile 7Li and by the lightest particle-stable lithium isotope 6Li on the same target. The angular distributions for the production of the two 7Be constituent clusters, namely 3He and 4He, were also measured. In agreement with what observed for the interaction of 7Be with lighter targets, the production of the heavier helium isotope resulted to be much more abundant than that of its lighter counterpart.

Reaction dynamics studies for the system 7Be + 208Pb at Coulomb barrier energies

Science.gov (United States)

Mazzocco, M.; Boiano, A.; Boiano, C.; La Commara, M.; Manea, C.; Parascandolo, C.; Pierroutsakou, D.; Strano, E.; Torresi, D.; Acosta, L.; Di Meo, P.; Fernandez-Garcia, J. P.; Glodariu, T.; Grebosz, J.; Guglielmetti, A.; Marquinez-Duran, G.; Martel, I.; Nicoletto, M.; Pakou, A.; Sánchez-Benítez, A. M.; Sava, T.; Sgouros, O.; Signorini, C.; Soramel, F.; Soukeras, V.; Stroe, L.

2017-11-01

The scattering process of the Radioactive Ion Beam 7Be from a 208Pb target was measured at three near-barrier energies. The quasi-elastic angular distributions were analyzed within the framework of the optical model to extract the reaction cross sections. The results are compared with those obtained for the reactions induced by the mirror projectile 7Li and by the lightest particle-stable lithium isotope 6Li on the same target. The angular distributions for the production of the two 7Be constituent clusters, namely 3He and 4He, were also measured. In agreement with what observed for the interaction of 7Be with lighter targets, the production of the heavier helium isotope resulted to be much more abundant than that of its lighter counterpart.

Control strategies for active noise barriers using near-field error sensing

NARCIS (Netherlands)

Berkhoff, Arthur P.

In this paper active noise control strategies for noise barriers are presented which are based on the use of sensors near the noise barrier. Virtual error signals are derived from these near-field sensor signals such that reductions of the far-field sound pressure are obtained with the active

Culture X: addressing barriers to physical activity in Samoa.

Science.gov (United States)

Heard, Emma Marie; Auvaa, Leveti; Conway, Brooke A

2017-08-01

There is an urgent need to address the epidemic rates of non-communicable diseases globally, and the Pacific Island region is of particular concern. Increasing physical activity participation plays an important role in reducing some of the key risk factors for non-communicable diseases including obesity and being overweight. In order to address low levels of physical activity, it is essential to understand the key barriers and facilitating factors experienced by specific population groups. The purpose of this study is to investigate key facilitating factors for participation in a dance aerobic initiative, Culture X, developed in the Pacific Island country, Samoa. The study further aims to understand ways in which the programme assists participants in addressing barriers to physical activity. Face-to-face interviews running from 10 to 20 min were conducted with 28 Culture X participants in order to gain a deep understanding of participants' personal perspectives with regard to barriers and facilitating factors to physical activity. Findings suggest the inclusion of key cultural components (including, traditional dance moves and music, prayer, community orientation and family inclusiveness) were integral for supporting ongoing participation in Culture X. These components further assisted participants in addressing important personal and social barriers to physical activity (including lack of motivation and enjoyment, lack of confidence, time management, family and social commitments and lack of support). This study highlights creative ways that health promotion in the Pacific Island region can encourage physical activity and informs health promotion literature regarding the importance of placing local culture at the heart of behaviour change initiatives. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

A systematic review of perceived barriers and motivators to physical activity after stroke.

Science.gov (United States)

Nicholson, Sarah; Sniehotta, Falko F; van Wijck, Frederike; Greig, Carolyn A; Johnston, Marie; McMurdo, Marion E T; Dennis, Martin; Mead, Gillian E

2013-07-01

Physical fitness is impaired after stroke, may contribute to disability, yet is amenable to improvement through regular physical activity. To facilitate uptake and maintenance of physical activity, it is essential to understand stroke survivors' perceived barriers and motivators. Therefore, we undertook a systematic review of perceived barriers and motivators to physical activity after stroke. Electronic searches of EMBASE, Medline, CINAHL, and PsychInfo were performed. We included peer-reviewed journal articles, in English, between 1 January 1966 and 30 August 2010 reporting stroke survivors' perceived barriers and motivators to physical activity. Searches identified 73,807 citations of which 57 full articles were retrieved. Six articles were included, providing data on 174 stroke survivors (range 10 to 83 per article). Two reported barriers and motivators, two reported only motivators, and two reported only barriers. Five were qualitative articles and one was quantitative. The most commonly reported barriers were lack of motivation, environmental factors (e.g. transport), health concerns, and stroke impairments. The most commonly reported motivators were social support and the need to be able to perform daily tasks. This review has furthered our understanding of the perceived barriers and motivators to physical activity after a stroke. This review will enable the development of tailored interventions to target barriers, while building upon perceived motivators to increase and maintain stroke survivors' physical activity. © 2012 The Authors. International Journal of Stroke © 2012 World Stroke Organization.

Socio-demographic and behavioral variation in barriers to leisure-time physical activity.

Science.gov (United States)

Borodulin, Katja; Sipilä, Noora; Rahkonen, Ossi; Leino-Arjas, Päivi; Kestilä, Laura; Jousilahti, Pekka; Prättälä, Ritva

2016-02-01

We examined the socio-demographic and behavioral determinants of perceived barriers to leisure-time physical activity (LTPA) in a population-based sample of working-aged adults. Data comprised the National FINRISK 2002 Study, a population-based health examination study. Analyses were restricted to those aged 25-64 years and who perceived that their amount of LTPA did not reach sufficient levels. They reported barriers to LTPA, defined as a lack of time, motivation and lack of companionship to be active with, as well as high expenses. Age, education, household income, employment status, family type, physical activity, smoking and body mass index (BMI) were included as explanatory variables. Lack of time was the most frequent barrier. Each barrier was explained by a different set of factors that also varied between genders. The strongest and most systematic associations with the barriers were found for age, employment status and family type. Lack of time was less often reported as a barrier among the unemployed, singles without children and older people. Lacking motivation as a barrier was most common among singles without children. High expenses as a barrier was more often reported by the unemployed, and less often reported in the highest income group. When considering actions to promote LTPA, there is not one single solution, because the perceived barriers vary by population subgroups. © 2015 the Nordic Societies of Public Health.

Physical Activity Pattern of Malaysian Preschoolers: Environment, Barriers, and Motivators for Active Play.

Science.gov (United States)

Lee, Shoo Thien; Wong, Jyh Eiin; Ong, Wei Wen; Ismail, Mohd Noor; Deurenberg, Paul; Poh, Bee Koon

2016-07-01

Children's physical activity has been correlated with child characteristics and social or physical environment. This study aimed to compare preschoolers' physical activity among various sociodemographic characteristics and to determine barriers, motivators, and environmental factors for active play. A total of 835 preschoolers were included in this analysis. Time spent on active play, quiet play, and screen time was reported by parents. Boys spent significantly more time on active play and screen time than girls. Time spent on quiet play was highest in East Coast Peninsular Malaysia and lowest in Sarawak. Some 40% of children achieved active play recommendation while 27% exceeded daily screen time recommendation. Most parents reported that their child played actively in the house area; and that the main barrier and motivator to active play were safety and child's enjoyment, respectively. These findings demonstrate that sociodemographic characteristics and environment should be considered in designing physical activity intervention programs. © 2016 APJPH.

Cross-sections and average angular momenta in fusion reactions near the coulomb barrier

International Nuclear Information System (INIS)

Dasgupta, M.

1992-01-01

In recent years there has been an increasing interest in the study of heavy ion collisions near the Coulomb barrier. This has been triggered mainly by the observations of enhancements by factors of about one to two order of magnitude in sub-Coulomb barrier fusion (SBF) cross-sections between medium mass nuclei, as compared to predictions based on one-dimensional barrier penetration model (l-d BPM). Though, a considerable amount of work both theoretical and experimental has been done in this field, a complete understanding of the SBF phenomenon has not yet been achieved. The relation between fusion excitation function and angular momentum (l) distribution in SBF reactions is a topic of current interest. It is believed that l-distributions provide a more stringent test of SBF models that the excitation functions alone. Simultaneous measurement of l-distribution (or its moments) and fusion excitation function is expected to lead to a better understanding of the relationship between these two qualities. Such information has been obtained in experiments done at pelletron accelerator facility. In the present talk the measurement of fusion cross-sections and the method of determination of average l from partial evaporation residue cross-section has been elaborated. An analysis of the experimental data on the basis of some of the SBF models has been discussed briefly. (author). 13 refs

Neighborhood disadvantage, physical activity barriers, and physical activity among African American breast cancer survivors

Directory of Open Access Journals (Sweden)

Antwan Jones

2015-01-01

Higher renter rates and individual barriers both contribute to lower levels of physical activity in African American breast cancer survivors. These data suggest that the potential for constant residential turnover (via rentership and perceived barriers may increase physical inactivity even where facilities may be available.

Can human activities alter the drowning fate of barrier islands?

Science.gov (United States)

Lorenzo-Trueba, J.; Ashton, A. D.; Jin, D.; Hoagland, P.; Kite-Powell, H.

2012-12-01

Low-lying coastal barriers face an uncertain future over the coming century and beyond as sea levels rise, with many projections suggesting end-of-century rates of sea-level rise as high or higher than 1 cm/yr. Geologically, such rates of sea-level rise have been experienced several thousand years ago and we can use our understanding of geological processes and sedimentary evidence to help unravel the dynamics of natural barriers experiencing sea-level rise. Along many modern coastal barriers, however, anthropic change, such as beach nourishment, dune construction, and emplacement of hard structures, plays a dominant role in coastline dynamics. A fundamental question to be addressed is whether human activities intended to preserve infrastructure and beach recreation may make wholesale collapse, or 'drowning,' of barrier systems more likely. Here we present a numerical modeling tool that couples natural processes and the human responses to these changes (and the subsequent of human responses on natural processes). Recent theoretical model development suggests that barriers are intrinsically morphodynamic features, responding to sea-level rise in complex ways through the interactions of marine processes and barrier overwash. Undeveloped coastal barriers would therefore respond to an accelerated sea-level rise in complex, less predictable manners than suggested by existing long-term models. We have developed a model that examines non-equilibrium cross-shore evolution of barrier systems at decadal to centennial temporal scales, focusing on the interactions between processes of shoreface evolution and overwash deposition. Model responses demonstrate two means of barrier collapse during sea-level rise: 'height drowning', which occurs when overwash fluxes are insufficient to maintain the landward migration rate required to keep in pace with sea-level rise, and 'width drowning', which occurs when the shoreface response is insufficient to maintain the barrier geometry

Music therapists' research activity and utilization barriers: a survey of the membership.

Science.gov (United States)

Waldon, Eric G

2015-01-01

Music therapists have access to a rapidly expanding body of research supporting the use of music-based interventions. What is not known is the extent to which music therapists access these resources and what factors may prevent them from incorporating research findings into clinical work. After constructing the Music Therapists' Research Activity and Utilization Barrier (MTRAUB) database, the purposes of this study involved: assessing the extent to which American Music Therapy Association (AMTA) members engage in certain research-related activities; and identifying respondents' perceived barriers to integrating research into clinical practice. This study employed a quantitative, non-experimental approach using an online survey. Respondents included professional, associate, student/graduate student, retired, inactive, and honorary life members of AMTA. Instrumentation involved a researcher-designed Background Questionnaire as well as the Barriers to Research Utilization Scale (BARRIERS; Funk, Champagne, Wiese, & Tornquist, 1991), a tool designed to assess perceived barriers to incorporating research into practice. Of the 3,194 survey invitations distributed, 974 AMTA members replied (a response rate of 30%). Regarding research-related activities, descriptive findings indicate that journal reading is the most frequently reported research-related activity while conducting research is the least frequently reported activity. Results from the BARRIERS Scale indicated that Organizational and Communication factors are perceived as interfering most prominently with the ability to utilize research in clinical practice. Findings suggest that research-related activity and perceived barriers vary as a function of educational attainment, work setting, and occupational role. The author discusses these differential findings in detail, suggests supportive mechanisms to encourage increased research activity and utilization, and offers recommendations for further analysis of the

Barriers to Physical Activity in a Mass Transit Population: A Qualitative Study.

Science.gov (United States)

Das, Bhibha M; Petruzzello, Steven J

2016-01-01

The physical inactivity epidemic continues be one of the greatest public health challenges in contemporary society in the United States. The transportation industry is at greater risk of physical inactivity, compared with individuals in other sectors of the workforce. The aim of this study was to use the Nominal Group Technique, a focus group technique, to examine mass transit employees' perceptions of the barriers to physical activity at their worksite. Three focus groups (n = 31) were conducted to examine mass transit employees' perceptions of barriers to physical activity at the worksite. Salient barriers included (1) changing work schedules, (2) poor weather conditions, and (3) lack of scheduled and timely breaks. Findings were consistent with previous research demonstrating shift work, poor weather, and lack of breaks can negatively impact mass transit employees' ability to be physically active. Although physical activity barriers for this population have been consistent for the last 20 years, public health practice and policy have not changed to address these barriers. Future studies should include conducing focus groups stratified by job classification (eg, operators, maintenance, and clerical) along with implementing and evaluating worksite-based physical activity interventions and policy changes.

Barriers and Facilitators of Physical Activity in Children of a South Asian Ethnicity

Directory of Open Access Journals (Sweden)

Lee Smith

2018-03-01

Full Text Available Children of South Asian ethnicity residing in England have low levels of physical activity. Limited literature exists on correlates, barriers, and facilitators to activity in South Asian children. The aim of this study was to fill this gap in the literature. Interviews were conducted with 10 parents of South Asian ethnicity residing in the UK. Interviews covered a description of the family setup, participants’ opinions of physical activity including barriers and facilitators and their children’s participation, as well as approaches to general parenting, and how children spend their free time. Data were analysed using thematic analysis. Key themes identified included (i restraints on parents’ and children’s time to be physically active; (ii the role of the family in children’s physical activity participation; (iii situational barriers to physical activity; (iv physical activity not a priority; (v opportunities to be active; and (vi perception of activity level and health. A number of key barriers to South Asian children’s participation in physical activity were identified, including (i restraints on parents and children’s time; (ii parents providing limited support for physical activity; and (iii physical activity having a low priority. A number of facilitators were also identified (i play; (ii school-time; and (iii extra-curricular clubs. In this sample of South Asian parents residing in the UK several socio-cultural barriers and facilitators of their children’s physical activity have been identified. The study provides preliminary data for a larger study to ascertain if such barriers and facilitators are representative of the wider South Asian community, so that recommendations for intervention and policies can be made.

Barriers associated with reduced physical activity in COPD patients

Directory of Open Access Journals (Sweden)

Priscila Batista Amorim

2014-10-01

Full Text Available OBJECTIVE: To evaluate the ability of COPD patients to perform activities of daily living (ADL; to identify barriers that prevent these individuals from performing ADL; and to correlate those barriers with dyspnea severity, six-minute walk test (6MWT, and an ADL limitation score. METHODS: In COPD patients and healthy, age-matched controls, the number of steps, the distance walked, and walking time were recorded with a triaxial accelerometer, for seven consecutive days. A questionnaire regarding perceived barriers and the London Chest Activity of Daily Living (LCADL scale were used in order to identify the factors that prevent the performance of ADL. The severity of dyspnea was assessed with two scales, whereas submaximal exercise capacity was determined on the basis of the 6MWT. RESULTS: We evaluated 40 COPD patients and 40 controls. In comparison with the control values, the mean walk time was significantly shorter for COPD patients (68.5 ± 25.8 min/day vs. 105.2 ± 49.4 min/day; p < 0.001, as was the distance walked (3.9 ± 1.9 km/day vs. 6.4 ± 3.2 km/day; p < 0.001. The COPD patients also walked fewer steps/day. The most common self-reported barriers to performing ADL were lack of infrastructure, social influences, and lack of willpower. The 6MWT distance correlated with the results obtained with the accelerometer but not with the LCADL scale results. CONCLUSIONS: Patients with COPD are less active than are healthy adults of a comparable age. Physical inactivity and the barriers to performing ADL have immediate implications for clinical practice, calling for early intervention measures.

Physical activity in hypertrophic cardiomyopathy: prevalence of inactivity and perceived barriers

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Sweeting, Joanna; Ingles, Jodie; Timperio, Anna; Patterson, Jillian; Ball, Kylie; Semsarian, Christopher

2016-01-01

Objectives This study aimed to determine the prevalence of physical inactivity and perceived barriers to physical activity among individuals with hypertrophic cardiomyopathy (HCM), and to determine potential demographic, clinical and health-related factors influencing likelihood of meeting physical activity guidelines. Methods This was a cross-sectional study of consecutive patients (n=198) with HCM attending a specialist HCM centre from July 2014 to November 2015. The primary outcome measure was physical activity (minutes per day), as measured by self-report (International Physical Activity Questionnaire (IPAQ)) and objective means (ActiGraph accelerometer). For both, participants were classified as meeting guidelines if they did at least 150 min per week of physical activity. Quality of life (Short Form-36 V.2, SF-36v2), barriers to exercise and clinical–demographic data were also collected. Results In total, 54.8% of participants did not meet physical activity recommendations based on IPAQ, and 12.7% did not meet guidelines based on accelerometer data. The most commonly identified barriers to exercise were ‘pain interferes with my exercise’ (33%) and ‘I have an injury/disability that stops me’ (29%). Independent factors associated with meeting guidelines included older age (OR 0.66, 95% CI 0.51 to 0.85, p=0.002), higher education level (OR 2.31, 95% CI 1.08 to 4.93, p=0.03), better physical quality of life (OR 1.05, 95% CI 1.0 to 1.09, p=0.05) and more reported barriers (OR 0.71, 95% CI 0.56 to 0.91, p=0.01). Conclusions More than half of the patients with HCM did not meet minimum physical activity recommendations. Several barriers to exercise among individuals with HCM exist, and provide the basis for targeted interventions to promote physical activity and improve overall health in patients with HCM. PMID:27547438

Collisions between heavy nuclei near the barrier

International Nuclear Information System (INIS)

Henning, W.

1988-05-01

Detailed information has recently become available on the reaction behavior in very heavy nuclear systems close to the Coulomb barrier. Starting from an experimental study of the distribution of the reaction strength above and below the barrier, the dominant reaction channels of quasi-elastic and strongly-damped processes are examined. With decreasing incident energy, the sub-barrier collisions are increasingly dominated by quasi-elastic processes. From the division of internal excitation energy, new information is obtained on the nature of the dissipative processes. (orig.)

Research on the application of active sound barriers for the transformer noise abatement

Directory of Open Access Journals (Sweden)

Hu Sheng

2016-01-01

Full Text Available Sound barriers are a type of measure most commonly used in the noise abatement of transformers. In the noise abatement project of substations, the design of sound barriers is restrained by the portal frames which are used to hold up outgoing lines from the main transformers, which impacts the noise reduction effect. If active sound barriers are utilized in these places, the noise diffraction of sound barriers can be effectively reduced. At a 110kV Substation, an experiment using a 15-channel active sound barrier has been carried out. The result of the experiment shows that the mean noise reduction value (MNRV of the noise measuring points at the substation boundary are 1.5 dB (A. The effect of the active noise control system is impacted by the layout of the active noise control system, the acoustic environment on site and the spectral characteristic of the target area.

Barriers Affecting Physical Activity in Rural Communities: Perceptions of Parents and Children

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McWhinney, Sharon; McDonald, Andrea; Dawkins-Moultin, Lenna; Outley, Corliss; McKyer, E. Lisako; Thomas, Audrene

2011-01-01

A comprehensive understanding of the barriers inhibiting physical activity among children is critical in the fight against childhood obesity. This qualitative interview study examined parents' and children's perceptions of the barriers to physical activity in rural communities of low socioeconomic status. Parents and children concurred that the…

Danish research-active clinical nurses overcome barriers in research utilization.

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Adamsen, Lis; Larsen, Kristian; Bjerregaard, Lene; Madsen, Jan K

2003-03-01

The aim of this study was to examine whether there was a difference between clinical nurses who were research-active, and clinical nurses who were nonresearch-active in utilization of research. A further aim was to identify the most significant barriers faced by a group of Danish clinical nurses in their use of research. Discrepancy between the improved quality of research results and the lack of implementing them was the starting point for a series of studies which showed the types of barriers clinical nurses found especially cumbersome when applying the research results of other researchers. This study investigates whether the clinical nurses' own engagement in research had any impact on their perception of research utilization. The study had an exploratory and descriptive design. Seventy-nine Danish clinical nurses participated and semi-structured interviewing was used as the research method. There was a statistically significant difference between the research-active and nonresearch-active nurses on various variables. The study showed that, to a larger extent, research-active nurses used evidence-based knowledge and were generally more internationally orientated. Furthermore, two important barriers for research utilization were identified by all 79 clinical nurses included in the study, i.e. 90% of the nurses explained that the quantity of research results was overwhelming, and 75% of them found that they were unable to evaluate the quality of the research. Clinical nurses, who were research-active themselves, experienced more success in overcoming some of the barriers, which existed in applying research to practice. The research potential found amongst clinical nurses in Denmark needed to be further supported through training and guidance in research methodology, establishing introductory stipends and part-time research positions. By doing so, some of the barriers affecting research utilization and the so-called theory-practice gap might be reduced. Further

Barriers to increased market-oriented activity

DEFF Research Database (Denmark)

Bisp, Søren

1999-01-01

and related activities still seem to attract relatively few resources is not answered by supplying another checklist or package of facilitators. Based on published conceptual writings and empirical studies this article makes an account of what the intra-organizational barriers may be to increased market......Most research on market orientation has dealt with assessing how market orientation behaviour is related to business performance. This work has established an intense market-oriented activity as significantly and positively related to business performance under most circumstances. In a maturing......-oriented activity. A framework of six generic domains is suggested: Organizational structure, human resource management, market-oriented activity competence, psychological climate, managers' personality characteristics, and individually held beliefs. A model is suggested inter-relating the domains....

Physical Activity and Youth with Disabilities: Barriers and Supports

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Block, Martin E.; Taliaferro, Andrea; Moran, Tom

2013-01-01

Physical activity and active use of leisure time is important for everyone but particularly important for youth with disabilities. Unfortunately, youth with disabilities often have a difficult time or are even excluded from participating in physical activity due to limited physical and cognitive skills, attitudinal barriers in the community, lack…

Perceived barriers to leisure-time physical activity and associated factors in adolescents.

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Dias, Douglas Fernando; Loch, Mathias Roberto; Ronque, Enio Ricardo Vaz

2015-11-01

The objective of this study was to identify the prevalence of perceived barriers to leisure-time physical activity in teenagers and to examine the possible association of these barriers with leisure-time physical inactivity. This cross-sectional study was conducted in 2011 and a representative sample of 1,409 high school students from public schools in the city of Londrina/Paraná was selected through multistage sampling. For data collection, the adolescents completed a questionnaire. The relationship between leisure-time physical inactivity (barriers was analyzed by calculating the prevalence ratio (PR) in Poisson regression models. "Lack of friends company" was the most prevalent barrier for both girls (75.8%) and boys (58.7%). "Feel lazy" for girls (PR: 1.21; CI 95%: 1.08 to 1.36) and "prefer to do other things" for the boys (PR: 1.48; CI 95%: 1.01 to 2.15) were the barriers most strongly associated with leisure-time physical inactivity. For both genders, a strong dose-response relationship was observed between the number of perceived barriers and leisure-time physical inactivity. The perception of barriers was associated with a higher prevalence of leisure-time physical inactivity in adolescents and should therefore be considered in actions for promoting physical activity in this population.The objective of this study was to identify the prevalence of perceived barriers to leisure-time physical activity in teenagers and to examine the possible association of these barriers with leisure-time physical inactivity. This cross-sectional study was conducted in 2011 and a representative sample of 1,409 high school students from public schools in the city of Londrina/Paraná was selected through multistage sampling. For data collection, the adolescents completed a questionnaire. The relationship between leisure-time physical inactivity (barriers was analyzed by calculating the prevalence ratio (PR) in Poisson regression models. "Lack of friends company" was the most

A qualitative theory guided analysis of stroke survivors' perceived barriers and facilitators to physical activity.

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Nicholson, Sarah L; Donaghy, Marie; Johnston, Marie; Sniehotta, Falko F; van Wijck, Frederike; Johnston, Derek; Greig, Carolyn; McMurdo, Marion E T; Mead, Gillian

2014-01-01

After stroke, physical activity and physical fitness levels are low, impacting on health, activity and participation. It is unclear how best to support stroke survivors to increase physical activity. Little is known about the barriers and facilitators to physical activity after stroke. Thus, our aim was to explore stroke survivors' perceived barriers and facilitators to physical activity. Semi-structured interviews with 13 ambulatory stroke survivors exploring perceived barriers and facilitators to physical activity post stroke were conducted in participants' homes, audio-recorded and transcribed verbatim. The Theoretical Domains Framework (TDF) informed content analysis of the interview transcripts. Data saturation was reached after interviews with 13 participants (median age of 76 years (inter-quartile range (IQR) = 69-83 years). The median time since stroke was 345 d (IQR = 316-366 d). The most commonly reported TDF domains were "beliefs about capabilities", "environmental context and resources" and "social influence". The most commonly reported perceived motivators were: social interaction, beliefs of benefits of exercise, high self-efficacy and the necessity of routine behaviours. The most commonly reported perceived barriers were: lack of professional support on discharge from hospital and follow-up, transport issues to structured classes/interventions, lack of control and negative affect. Stroke survivors perceive several different barriers and facilitators to physical activity. Stroke services need to address barriers to physical activity and to build on facilitators to promote physical activity after stroke. Physical activity post stroke can improve physical fitness and function, yet physical activity remains low among stroke survivors. Understanding stroke survivors' perceived barriers and facilitators to physical activity is essential to develop targeted interventions to increase physical activity. Beliefs about capabilities, environmental

Densification of Ce0.9Gd0.1O1.95 barrier layer by in-situ solid state reaction

DEFF Research Database (Denmark)

Ni, De Wei; Esposito, Vincenzo

2014-01-01

A novel methodology, called in-situ solid state reaction (SSR), is developed and achieved for the densification of gadolinia doped ceria (CGO) barrier layer (BL) within the solid oxide fuel cell (SOFC) technology. The method is based on the combined use of impregnation technique and a designed two...

Barriers to participation in physical activity and exercise among middle-aged and elderly individuals.

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Justine, Maria; Azizan, Azliyana; Hassan, Vaharli; Salleh, Zoolfaiz; Manaf, Haidzir

2013-10-01

INTRODUCTION Although the benefits of physical activity and exercise are widely acknowledged, many middle-aged and elderly individuals remain sedentary. This cross-sectional study aimed to identify the external and internal barriers to physical activity and exercise participation among middle-aged and elderly individuals, as well as identify any differences in these barriers between the two groups. METHODS Recruited individuals were categorised into either the middle-aged (age 45-59 years, n = 60) or elderly (age ≥ 60 years, n = 60) group. Data on demographics, anthropometry, as well as external and internal barriers to participation in physical activity and exercise were collected. RESULTS Analysis showed no significant differences in the total scores of all internal barriers between the two groups (p > 0.05). The total scores for most external barriers between the two groups also showed no significant differences (p > 0.05); only 'cost' (p = 0.045) and 'exercise interferes with social/family activities' (p = 0.011) showed significant differences. The most common external barriers among the middle-aged and elderly respondents were 'not enough time' (46.7% vs. 48.4%), 'no one to exercise with' (40.0% vs. 28.3%) and 'lack of facilities' (33.4% vs. 35.0%). The most common internal barriers for middle-aged respondents were 'too tired' (48.3%), 'already active enough' (38.3%), 'do not know how to do it' (36.7%) and 'too lazy' (36.7%), while those for elderly respondents were 'too tired' (51.7%), 'lack of motivation' (38.4%) and 'already active enough' (38.4%). CONCLUSION Middle-aged and elderly respondents presented with similar external and internal barriers to physical activity and exercise participation. These factors should be taken into account when healthcare policies are being designed and when interventions such as the provision of facilities to promote physical activity and exercise among older people are being considered.

Fusion cross sections for 6,7Li + 24Mg reactions at energies below and above the barrier

International Nuclear Information System (INIS)

Ray, M.; Mukherjee, A.; Pradhan, M. K.; Kshetri, Ritesh; Sarkar, M. Saha; Dasmahapatra, B.; Palit, R.; Majumdar, I.; Joshi, P. K.; Jain, H. C.

2008-01-01

Measurement of fusion cross sections for the 6,7 Li + 24 Mg reactions by the characteristic γ-ray method has been done at energies from below to well above the respective Coulomb barriers. The fusion cross sections obtained from these γ-ray cross sections for the two systems are found to agree well with the total reaction cross sections at low energies. The relatively large difference between total cross sections and measured fusion cross sections at higher energies is consistent with the fact that other channels, in particular breakup, open up with an increase of bombarding energy. The breakup channel, however, appears not to have any influence on fusion cross sections. The critical angular momenta (l cr ) deduced from the fusion cross sections are found to have an energy dependence similar to other Li-induced reactions

Barriers to fusion

International Nuclear Information System (INIS)

Berriman, A.C.; Butt, R.D.; Dasgupta, M.; Hinde, D.J.; Morton, C.R.; Newton, J.O.

1999-01-01

The fusion barrier is formed by the combination of the repulsive Coulomb and attractive nuclear forces. Recent research at the Australian National University has shown that when heavy nuclei collide, instead of a single fusion barrier, there is a set of fusion barriers. These arise due to intrinsic properties of the interacting nuclei such deformation, rotations and vibrations. Thus the range of barrier energies depends on the properties of both nuclei. The transfer of matter between nuclei, forming a neck, can also affect the fusion process. High precision data have been used to determine fusion barrier distributions for many nuclear reactions, leading to new insights into the fusion process

Explore the reaction mechanism of the Maillard reaction: a density functional theory study.

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Ren, Ge-Rui; Zhao, Li-Jiang; Sun, Qiang; Xie, Hu-Jun; Lei, Qun-Fang; Fang, Wen-Jun

2015-05-01

The mechanism of Maillard reaction has been investigated by means of density functional theory calculations in the gaseous phase and aqueous solution. The Maillard reaction is a cascade of consecutive and parallel reaction. In the present model system study, glucose and glycine were taken as the initial reactants. On the basis of previous experimental results, the mechanisms of Maillard reaction have been proposed, and the possibility for the formation of different compounds have been evaluated through calculating the relative energy changes for different steps of reaction under different pH conditions. Our calculations reveal that the TS3 in Amadori rearrangement reaction is the rate-determining step of Maillard reaction with the activation barriers of about 66.7 and 68.8 kcal mol(-1) in the gaseous phase and aqueous solution, respectively. The calculation results are in good agreement with previous studies and could provide insights into the reaction mechanism of Maillard reaction, since experimental evaluation of the role of intermediates in the Maillard reaction is quite complicated.

Physical activity barriers and enablers in older Veterans with lower-limb amputation.

Science.gov (United States)

Littman, Alyson J; Boyko, Edward J; Thompson, Mary Lou; Haselkorn, Jodie K; Sangeorzan, Bruce J; Arterburn, David E

2014-01-01

Little is known about the types of physical activities that older individuals with lower-limb loss perform, correlates of regular physical activity (PA), and barriers and facilitators to PA. We conducted an exploratory study in 158 older Veterans from the Pacific Northwest with a partial foot (35%), below-knee (39%) and above-knee (26%) amputation. Ninety-eight percent of survey respondents were male, on average 65 yr of age and 15 yr postamputation; 36% of amputations were trauma-related. The most commonly reported physical activities were muscle strengthening (42%), yard work and/or gardening (30%), and bicycling (11%). Forty-three percent were classified as physically active based on weekly moderate- and vigorous-intensity PA. History of vigorous preamputation PA was positively associated with being active, while low wealth and watching ≥5 h/d of television/videos were inversely associated. While pain- and resource-related barriers to PA were most frequently reported, only knowledge-related and interest/motivation-related barriers were inversely associated with being active. Family support and financial assistance to join a gym were the most commonly reported factors that would facilitate PA. To increase PA in the older amputee population, interventions should address motivational issues, knowledge gaps, and television watching; reduce financial barriers to exercising; and consider involving family members.

Motivators and barriers for physical activity in older adults with osteoporosis.

Science.gov (United States)

Baert, Veerle; Gorus, Ellen; Mets, Tony; Bautmans, Ivan

2015-01-01

Although physical activity (PA) is an important tool to counter osteoporosis, too few older patients with osteoporosis (OPWO) engage in PA. Little is known about specific motivators for and barriers to PA in OPWO, hindering the development of targeted PA promotion campaigns for these persons. Therefore, the main objective of this study was to identify motivators for and barriers to PA specifically in OPWO. This qualitative study identified specific motivators for and barriers to PA in OPWO through 2 different methods: focus groups with professionals and in-depth interviews with OPWO. The OPWO tended to give a broad interpretation of what they considered as PA (practicing sports, physical work, and performing household activities), whereas the professionals seemed to mainly focus on (therapeutic) exercise as PA. Fifteen different motivators and 18 barriers have been identified. Among others, health improvement, social contact, habit, feeling good, and receiving medical advice from a medical doctor were motivators. Pain, fear of falling, bad weather, lack of interest, and caring for an ill partner were barriers to PA. For some older respondents, osteoporosis acted as a trigger for PA, and for others it was a barrier. This study emphasizes the importance for health care professionals to give personalized PA advice regarding the nature and frequency of PA that is safe and beneficial for osteoporosis. It stands to reason that the information about PA needs to be clear and consistent. Furthermore, it is quintessential to mention that it can take some time to adapt to physical exercise and to experience the beneficial effects, because pain sensations during the first PA sessions can be perceived as barriers to OPWO. Misconceptions or barriers to PA should be countered by assessing motivators for and barriers to PA by the health care professional together with the older client so that barriers can be eliminated and motivators can be strengthened. Physical activity

Desmoglein 2 regulates the intestinal epithelial barrier via p38 mitogen-activated protein kinase.

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Ungewiß, Hanna; Vielmuth, Franziska; Suzuki, Shintaro T; Maiser, Andreas; Harz, Hartmann; Leonhardt, Heinrich; Kugelmann, Daniela; Schlegel, Nicolas; Waschke, Jens

2017-07-24

Intestinal epithelial barrier properties are maintained by a junctional complex consisting of tight junctions (TJ), adherens junctions (AJ) and desmosomes. Desmoglein 2 (Dsg2), an adhesion molecule of desmosomes and the only Dsg isoform expressed in enterocytes, is required for epithelial barrier properties and may contribute to barrier defects in Crohn's disease. Here, we identified extradesmosomal Dsg2 on the surface of polarized enterocytes by Triton extraction, confocal microscopy, SIM and STED. Atomic force microscopy (AFM) revealed Dsg2-specific binding events along the cell border on the surface of enterocytes with a mean unbinding force of around 30pN. Binding events were blocked by an inhibitory antibody targeting Dsg2 which under same conditions activated p38MAPK but did not reduce cell cohesion. In enterocytes deficient for Dsg2, p38MAPK activity was reduced and both barrier integrity and reformation were impaired. Dsc2 rescue did not restore p38MAPK activity indicating that Dsg2 is required. Accordingly, direct activation of p38MAPK in Dsg2-deficient cells enhanced barrier reformation demonstrating that Dsg2-mediated activation of p38MAPK is crucial for barrier function. Collectively, our data show that Dsg2, beside its adhesion function, regulates intestinal barrier function via p38MAPK signalling. This is in contrast to keratinocytes and points towards tissue-specific signalling functions of desmosomal cadherins.

Effects of Water Molecule on CO Oxidation by OH: Reaction Pathways, Kinetic Barriers, and Rate Constants.

Science.gov (United States)

Zhang, Linyao; Yang, Li; Zhao, Yijun; Zhang, Jiaxu; Feng, Dongdong; Sun, Shaozeng

2017-07-06

The water dilute oxy-fuel combustion is a clean combustion technology for near-zero emission power; and the presence of water molecule could have both kinetic and dynamic effects on combustion reactions. The reaction OH + CO → CO 2 + H, one of the most important elementary reactions, has been investigated by extensive electronic structure calculations. And the effects of a single water molecule on CO oxidation have been studied by considering the preformed OH(H 2 O) complex reacts with CO. The results show little change in the reaction pathways, but the additional water molecule actually increases the vibrationally adiabatic energy barriers (V a G ). Further thermal rate constant calculations in the temperature range of 200 to 2000 K demonstrate that the total low-pressure limit rate constant for the water assisted OH(H 2 O) + CO → CO 2 + H 2 O + H reaction is 1-2 orders lower than that of the water unassisted one, which is consistent with the change of V a G . Therefore, the hydrated radical OH(H 2 O) would actually slow down the oxidation of CO. Meanwhile, comparisons show that the M06-2X/aug-cc-pVDZ method gives a much better estimation in energy and thus is recommended to be employed for direct dynamics simulations.

Reaction of LiD with moisture by temperature programmed reaction (TPR)

International Nuclear Information System (INIS)

Dinh, L N; Balooch, M; Cecala, C M; Leckey, J H

2000-01-01

The temperature programmed reaction technique was performed on LiOH powders and LiD single crystals previously exposed to different moisture levels. Our results show that the LiOH decomposition process has an activation energy barrier of 30 to 33.1 kcal/mol. The LiOH structure is stable at 320 K for 100 years. However, LiOH structures formed on the surface of LiD during moisture exposure at low dosages may have multiple activation energy barriers, some of which may be much lower than 30 kcal/mol. We attribute the lowering of the activation energy barrier for the LiOH decomposition to the existence of dangling bonds, cracks, and other long range disorders in the LiOH structures formed at low levels of moisture exposure. These defective LiOH structures may decompose significantly over the next 100 years of storage even at room temperature. At high moisture exposure levels, LiOH.H 2 O formation is observed. The release of H 2 O molecules from LiOH.H 2 O structure has small activation energy barriers in the range of 13.8 kcal/mol to 16.0 kcal/mol. The loosely bonded H 2 O molecules in the LiOH.H 2 O structure can be easily pumped away at room temperature in a reasonable amount of time. Our experiments also suggest that handling LiD single crystals at an elevated temperature of 340 K or more reduces the growth of LiOH and LiOH.H 2 O significantly

Reaction mechanisms in heavy ion fusion

Directory of Open Access Journals (Sweden)

Lubian J.

2011-10-01

Full Text Available We discuss the reaction mechanisms involved in heavy ion fusion. We begin with collisions of tightly bound systems, considering three energy regimes: energies above the Coulomb barrier, energies just below the barrier and deep sub-barrier energies. We show that channel coupling effects may influence the fusion process at above-barrier energies, increasing or reducing the cross section predicted by single barrier penetration model. Below the Coulomb barrier, it enhances the cross section, and this effect increases with the system’s size. It is argued that this behavior can be traced back to the increasing importance of Coulomb coupling with the charge of the collision partners. The sharp drop of the fusion cross section observed at deep sub-barrier energies is addressed and the theoretical approaches to this phenomenon are discussed. We then consider the reaction mechanisms involved in fusion reactions of weakly bound systems, paying particular attention to the calculations of complete and incomplete fusion available in the literature.

Development of the Barriers to Physical Activity Questionnaire for People with Mobility Impairments.

Science.gov (United States)

Vasudevan, Vijay; Rimmer, James H; Kviz, Frederick

2015-10-01

Despite the widely known benefits of physical activity, people with disabilities are more likely to be inactive when compared to people without disabilities. Previous questionnaires that measure barriers physical activity for people with disabilities do not measure barriers from an ecological perspective. The purpose of this study was to develop the Barriers to Physical Activity Questionnaire for People with Mobility Impairments (BPAQ-MI) that measures barriers using an ecological framework. This study consisted of two phases. In Phase one, developed the content validity by (a) developing an item bank, (b) identifying missing items and combining items using a Delphi panel, and (c) refine item wording via cognitive interviews. In Phase two, people with mobility impairments took part in in-person interviews to establish test-retest reliability, internal consistency, and construct validity of the BPAQ-MI. Exploratory factor analysis revealed the BPAQ-MI was comprised of eight subscales or factors: health; beliefs and attitudes; family; friends; fitness center built environment; staff and policy; community built environment; and safety. The BPAQ-MI demonstrated very good test-retest reliability. Cronbach's alpha ranged from 0.792 to 0.935. The BPAQ-MI showed significant negative correlations with exercise (minutes/week) and significant positive correlations between BPAQ-MI subscales and inactivity (hours/day). The BPAQ-MI is the first questionnaire that places greater equity at measuring barriers to physical activity across the intrapersonal, interpersonal, organizational, and community domains. The BPAQ-MI has the potential to assist researchers in understanding the complex relationship between barriers and ultimately develop physical activity interventions that address these barriers. Copyright © 2015 Elsevier Inc. All rights reserved.

Predictors of physical activity and barriers to exercise in nursing and medical students.

Science.gov (United States)

Blake, Holly; Stanulewicz, Natalia; Mcgill, Francesca

2017-04-01

To investigate physical activity levels of nursing and medicine students, examine predictors of physical activity level and examine the most influential benefits and barriers to exercise. Healthcare professionals have low levels of physical activity, which increases their health risk and may influence their health promotion practices with patients. We surveyed 361 nursing (n = 193) and medicine (n = 168) students studying at a UK medical school. Questionnaire survey, active over 12 months in 2014-2015. Measures included physical activity level, benefits and barriers to exercise, social support, perceived stress and self-efficacy for exercise. Many nursing and medicine students did not achieve recommended levels of physical activity (nursing 48%; medicine 38%). Perceived benefits of exercise were health related, with medicine students identifying additional benefits for stress relief. Most notable barriers to exercise were as follows: lack of time, facilities having inconvenient schedules and exercise not fitting around study or placement schedules. Nursing students were less active than medicine students; they perceived fewer benefits and more barriers to exercise and reported lower social support for exercise. Physical activity of nursing and medicine students was best predicted by self-efficacy and social support, explaining 35% of the variance. Physical activity should be promoted in nursing and medicine students. Interventions should aim to build self-efficacy for exercise and increase social support. Interventions should be developed that are targeted specifically to shift-working frontline care staff, to reduce schedule-related barriers to exercise and to increase accessibility to workplace health and well-being initiatives. © 2016 John Wiley & Sons Ltd.

Potential surfaces in symmetric heavy-ion reactions

International Nuclear Information System (INIS)

Royer, G.; Piller, C.; Mignen, J.; Raffray, Y.

1989-01-01

The entrance channel in symmetric heavy-ion reactions is studied in the liquid-drop model approach including the nuclear proximity energy and allowing ellipsoidal deformations of the colliding nuclei. In the whole mass range a sudden transition occurs from oblate to prolate shapes when the proximity forces become important. This strongly affects the effective moment of inertia. The ellipsoidal deformations reduce the fusion barrier width for light systems and lower the potential barrier height for medium and heavy nuclei. The results are in agreement with the empirical effective barrier shift determined by Aguiar et al for the 58 Ni + 58 Ni, 74 Ge + 74 Ge and 80 Se + 80 Se systems. The sub-barrier fusion enhancement in heavy-ion reactions might be explained by the slowness of the process. Below the static fusion barrier, the reaction time is long; allowing some adiabaticity and deformations of the colliding ions. Above the barrier, the reaction is more sudden and the deformation degree of freedom is frozen

Barriers related to physical activity practice in adolescents. A focus-group study

Directory of Open Access Journals (Sweden)

Ciro Romélio Rodriguez Añez

2010-04-01

Full Text Available The aim of study was to identify barriers to physical activity in adolescents. Focus group interviews were conducted with subjects aged 15 to 18 years (n=59, 50.8% girls and divided according to gender. Content analysis was used to classify the reports into specific dimensions. Descriptive statistics employing relative and absolute frequencies of similar reports was performed using the SPSS 11.0 software. The most frequent barriers among adolescents were those associated with “psychological, cognitive and emotional” and “cultural and social” dimensions. For boys, the most frequently reported barriers were “feeling lazy”, “lack of company” and “lack of time”. For girls, “feeling lazy”, “lack of com-pany” and “occupation” were the most common barriers. In conclusion, the perception of barriers by adolescents varies according to gender, a fact requiring specific actions for the promotion of physical activity in this group.

Perceived barriers and facilitators to physical activity for children with disability: a systematic review.

Science.gov (United States)

Shields, Nora; Synnot, Anneliese Jane; Barr, Megan

2012-11-01

The aim of this systematic review was to investigate the perceived barriers and facilitators to physical activity among children with disability. 10 electronic databases were searched from the earliest time available to September 2010 to identify relevant articles. Articles were included if they examined the barriers or facilitators to physical activity for children with disability and were written in English. Articles were excluded if they included children with an acute, transient or chronic medical condition, examined sedentary leisure activities, or societal participation in general. Two reviewers independently assessed the search yields, extracted the data and assessed trial quality. Data were analysed descriptively. 14 articles met the inclusion criteria. Barriers included lack of knowledge and skills, the child's preferences, fear, parental behaviour, negative attitudes to disability, inadequate facilities, lack of transport, programmes and staff capacity, and cost. Facilitators included the child's desire to be active, practising skills, involvement of peers, family support, accessible facilities, proximity of location, better opportunities, skilled staff and information. Personal, social, environmental, and policy and programme-related barriers and facilitators influence the amount of activity children with disability undertake. The barriers to physical activity have been studied more comprehensively than the facilitators.

Adolescent Girls' Perceived Barriers to Participation in Physical Activity

Science.gov (United States)

Dwyer, John J. M.; Allison, Kenneth R.; Goldenberg, Ellie R.; Fein, Allan J.; Yoshida, Karen K.; Boutilier, Marie A.

2006-01-01

Research shows a decline in physical activity levels during adolescence, particularly among girls. This study explored perceived barriers to participation in moderate and vigorous physical activity among adolescent girls who live in a large ethnoracially and socioeconomically diverse city. A total of 73 adolescent girls in Toronto participated in…

Characteristics of powdered activated carbon treated with dielectric barrier discharge for electric double-layer capacitors

International Nuclear Information System (INIS)

Tashima, Daisuke; Yoshitama, Hiromu; Sakoda, Tatsuya; Okazaki, Akihito; Kawaji, Takayuki

2012-01-01

Highlights: ► The specific capacitance of the EDLCs could be improved by oxygen plasma treatment. ► 15 s treated EDLCs showed a 20% increase in capacitance relative to untreated EDLCs. ► The plasma treatment yields EDLCs that are suitable for high-energy applications. - Abstract: The electrochemical properties of electric double-layer capacitors (EDLCs) made with plasma-treated powdered activated carbon (treated using a dielectric barrier discharge) were examined using cyclic voltammetry (CV), Cole–Cole plots, and X-ray photoelectron spectroscopy (XPS). The dielectric barrier discharge method, which operates at atmospheric pressure, dramatically reduces the processing time and does not require vacuum equipment, making it a more practical alternative than low-pressure plasma treatment. The experimental data indicate that the specific capacitance of the EDLCs could be improved by oxygen plasma treatment. Capacitance of EDLCs made with activated carbon treated for 15 s showed 193.5 F/g that 20% increase in the specific capacitance relative to untreated EDLCs. This result indicates that the plasma treatment yields EDLCs that are suitable for high-energy applications. The enhancement of capacitance was mainly attributed to an increase in the BET surface area of the activated carbon and the creation of carboxyl groups on the surface of the carbon. The carboxyl groups induced oxidation–reduction reactions in the presence of O 2 which was included in the operation gas. In addition, the carboxyl groups improved the penetration of the electrolyte solution into the carbon electrodes.

Municipal Officials’ Perceived Barriers to Consideration of Physical Activity in Community Design Decision Making

Science.gov (United States)

Goins, Karin Valentine; Schneider, Kristin L.; Brownson, Ross; Carnoske, Cheryl; Evenson, Kelly; Eyler, Amy; Heinrich, Katie; Litt, Jill; Lyn, Rodney; Maddock, Jay; Reed, Hannah; Tompkins, Nancy O’Hara; Lemon, Stephenie C.

2016-01-01

Context Built environment-focused interventions and policies are recommended as sustainable approaches for promoting physical activity. Physical activity has not traditionally been considered in land use and transportation decision making. Effective collaboration with non-public health partners requires knowledge of their perceived barriers to consideration of physical activity in decision making. Objective This study aimed to 1) identify barriers to the consideration of physical activity in community design and planning decisions among municipal decision makers and 2) explore differences in these barriers among a wide range of job functions and departments in a geographically diverse sample. Design A web-based survey was conducted among municipal officials in 94 cities and towns with populations of at least 50,000 residents in eight states. Participants 453 municipal officials from public health, planning, transportation/public works, community and economic development, parks and recreation, city management, and municipal legislatures responded to the survey. Main Outcome Measures Five barriers to consideration of physical activity in community design and layout were assessed. Results The most common barriers included lack of political will (23.5%), limited staff (20.4%) and lack of collaboration across municipal departments (16.2%). Fewer participants reported opposition from the business community or residents as barriers. Compared to other professionals, public health department personnel were more likely to report the barriers of limited staff and lack of collaboration across municipal departments. They were also more likely to report lack of political will compared to city managers or mayors and municipal legislators. Conclusions Barriers to increasing consideration of physical activity in decision making about community design and layout are encouragingly low. Implications for public health practice include the need to strategically increase political will

Investigation of the CH3Cl + CN(-) reaction in water: Multilevel quantum mechanics/molecular mechanics study.

Science.gov (United States)

Xu, Yulong; Zhang, Jingxue; Wang, Dunyou

2015-06-28

The CH3Cl + CN(-) reaction in water was studied using a multilevel quantum mechanics/molecular mechanics (MM) method with the multilevels, electrostatic potential, density functional theory (DFT) and coupled-cluster single double triple (CCSD(T)), for the solute region. The detailed, back-side attack SN2 reaction mechanism was mapped along the reaction pathway. The potentials of mean force were calculated under both the DFT and CCSD(T) levels for the reaction region. The CCSD(T)/MM level of theory presents a free energy activation barrier height at 20.3 kcal/mol, which agrees very well with the experiment value at 21.6 kcal/mol. The results show that the aqueous solution has a dominant role in shaping the potential of mean force. The solvation effect and the polarization effect together increase the activation barrier height by ∼11.4 kcal/mol: the solvation effect plays a major role by providing about 75% of the contribution, while polarization effect only contributes 25% to the activation barrier height. Our calculated potential of mean force under the CCSD(T)/MM also has a good agreement with the one estimated using data from previous gas-phase studies.

Motives for and barriers to physical activity in twin pairs discordant for leisure time physical activity for 30 years.

Science.gov (United States)

Aaltonen, S; Leskinen, T; Morris, T; Alen, M; Kaprio, J; Liukkonen, J; Kujala, U

2012-02-01

Long-term persistent physical activity is important in the prevention of chronic diseases, but a large number of people do not participate in physical activity to obtain health benefits. The purpose of this study was to examine the motives and perceived barriers to long-term engagement in leisure time physical activity. Same-sex twin pairs (N=16, mean age 60) discordant for physical activity over 30 years were identified from the Finnish Twin Cohort. We evaluated participants' physical activity motivation with the 73-item Recreational Exercise Motivation Measure and assessed barriers to physical activity with a 25-item questionnaire. The characteristics of physical activity motivation and perceived barriers between the active and inactive co-twins were analysed using paired tests. Motives related to the sub-dimensions of enjoyment and physical fitness and psychological state were the most important reasons for participation in physical activity among all the twin individuals analysed. The sub-dimensions mastery (p=0.018, Cohen's d=0.76), physical fitness (p=0.029, Cohen's d=0.69), and psychological state (p=0.039, Cohen's d=0.65) differed significantly between active and inactive co-twins. More than half of the participants reported no reasons for not being physically active. If reasons existed, participation in physical activity was deterred mostly by pain and various health problems. This study found no differences in perceived barriers between active and inactive co-twins. We conclude from our results that the main factors promoting persistent leisure time physical activity were participants' wish to improve or maintain their physical skills or techniques, a feeling that exercise would improve their mental and physical health and that they found the activity enjoyable. This study helps us understand the importance of the role of motives and the minor role of perceived barriers for engagement in persistent physical activity. © Georg Thieme Verlag KG Stuttgart �

Total reaction cross section for 12C+16O below the Coulomb barrier

International Nuclear Information System (INIS)

Cujec, B.; Barnes, C.A.

1976-01-01

The energy dependence of the total reaction cross section, sigma(E), for 12 C+ 16 0 has been measured over the range Esub(c.m.)=4-12 MeV, by detecting γ-rays from the various possible residual nuclei with two large NaI(Tl) detectors placed close to the target. This technique for measuring total reaction cross sections was explored in some detail and shown to yield reliable values for sigma(E). Although the principal emphasis of this work was placed on obtaining reliable cross sections, a preliminary study has been made of the suitability of various methods for extrapolating the cross section to still lower energies. The statistical model provides a good fit with a reasonable value for the strength function, 2 >/ =6.8x10 -2 , over the range Esub(c.m.)=6.5-12 MeV, but predicts cross sections which are much too large for Esub(c.m.)<6.5 MeV. Optical model fits at low energies are especially sensitive to the radius and diffuseness of the imaginary component of the potential and, since these are still poorly known at present, such extrapolations may be wrong by orders of magnitude. A simple barrier penetration model gives a moderately good fit to the data and seems to provide the safest extrapolation to lower energies at the present time. It is clear, however, that our knowledge of the heavy-ion reaction mechanism at low energies is incomplete, and that cross-section measurements at still lower energies are needed to establish the correct procedure for extrapolating heavy-ion reaction cross sections to low energies. (Auth.)

Reaction of H2 with O2 in Excited Electronic States: Reaction Pathways and Rate Constants.

Science.gov (United States)

Pelevkin, Alexey V; Loukhovitski, Boris I; Sharipov, Alexander S

2017-12-21

Comprehensive quantum chemical analysis with the use of the multireference state-averaged complete active space self-consistent field approach was carried out to study the reactions of H 2 with O 2 in a 1 Δ g , b 1 Σ g + , c 1 Σ u - , and A' 3 Δ u electronically excited states. The energetically favorable reaction pathways and possible intersystem crossings have been revealed. The energy barriers were refined employing the extended multiconfiguration quasi-degenerate second-order perturbation theory. It has been shown that the interaction of O 2 (a 1 Δ g ) and O 2 (A' 3 Δ u ) with H 2 occurs through the H-abstraction process with relatively low activation barriers that resulted in the formation of the HO 2 molecule in A″ and A' electronic states, respectively. Meanwhile, molecular oxygen in singlet sigma states (b 1 Σ g + and c 1 Σ u - ) was proved to be nonreactive with respect to the molecular hydrogen. Appropriate rate constants for revealed reaction and quenching channels have been estimated using variational transition-state theory including corrections for the tunneling effect, possible nonadiabatic transitions, and anharmonicity of vibrations for transition states and reactants. It was demonstrated that the calculated reaction rate constant for the H 2 + O 2 (a 1 Δ g ) process is in reasonable agreement with known experimental data. The Arrhenius approximations for these processes have been proposed for the temperature range T = 300-3000 K.

Quantitative data analysis of perceived barriers and motivators to physical activity in stroke survivors.

Science.gov (United States)

Nicholson, S L; Greig, C A; Sniehotta, F; Johnston, M; Lewis, S J; McMurdo, M E; Johnston, D; Scopes, J; Mead, G E

2017-09-01

Levels of physical activity after stroke are low, despite multiple health benefits. We explored stroke survivors' perceived barriers, motivators, self-efficacy and intention to physical activity. Fifty independently mobile stroke survivors were recruited prior to hospital discharge. Participants rated nine possible motivators and four possible barriers based on the Mutrie Scale, as having 'no influence', 'some influence' or 'a major influence' on physical activity. Participants also rated their self-efficacy and intention to increasing walking. The most common motivator was 'physical activity is good for health' [34 (68%)]. The most common barrier was 'feeling too tired' [24 (48%)]. Intention and self-efficacy were high. Self-efficacy was graded as either 4 or 5 (highly confident) on a five-point scale by [34 (68%)] participants, while 42 (84%) 'strongly agreed' or 'agreed' that they intended to increase their walking. Participants felt capable of increasing physical activity but fatigue was often perceived as a barrier to physical activity. This needs to be considered when encouraging stroke survivors to be more active.

Barriers to physical activity between adults with stroke and their care partners.

Science.gov (United States)

Zalewski, Kathryn R; Dvorak, Leah

2011-10-01

Healthy living includes meeting daily physical activity guidelines. This study compares daily physical activity rates and barriers to physical activity for people with stroke and their partners (spouse or significant other). Physical abilities, energy expenditure, daily steps, and barriers to physical activity are evaluated in people who have completed stroke rehabilitation and their partners. Twenty pairs of adults (mean age 69.7 years) participated. Participants with stroke were classified as sedentary, averaging 2,990 (± 2,488) steps per day. Their partners are classified as low active, averaging 6,378 (± 2,149) steps per day. For stroke survivors, physical abilities were positively correlated to daily activity rates. The number of steps walked per day was moderately correlated to 6-minute walk tests (r = 0.550, P physical abilities were not correlated to daily physical activity. People with stroke report lack of skill as a primary barrier; their partners report lack of time. The relationship between physical ability and physical activity is reinforced with this study. The impact of stroke on the family, particularly on time demands of the primary caregiver, suggests the needs of the care partner may not be adequately addressed in the rehabilitation process.

Benchmarking density functional tight binding models for barrier heights and reaction energetics of organic molecules.

Science.gov (United States)

Gruden, Maja; Andjeklović, Ljubica; Jissy, Akkarapattiakal Kuriappan; Stepanović, Stepan; Zlatar, Matija; Cui, Qiang; Elstner, Marcus

2017-09-30

Density Functional Tight Binding (DFTB) models are two to three orders of magnitude faster than ab initio and Density Functional Theory (DFT) methods and therefore are particularly attractive in applications to large molecules and condensed phase systems. To establish the applicability of DFTB models to general chemical reactions, we conduct benchmark calculations for barrier heights and reaction energetics of organic molecules using existing databases and several new ones compiled in this study. Structures for the transition states and stable species have been fully optimized at the DFTB level, making it possible to characterize the reliability of DFTB models in a more thorough fashion compared to conducting single point energy calculations as done in previous benchmark studies. The encouraging results for the diverse sets of reactions studied here suggest that DFTB models, especially the most recent third-order version (DFTB3/3OB augmented with dispersion correction), in most cases provide satisfactory description of organic chemical reactions with accuracy almost comparable to popular DFT methods with large basis sets, although larger errors are also seen for certain cases. Therefore, DFTB models can be effective for mechanistic analysis (e.g., transition state search) of large (bio)molecules, especially when coupled with single point energy calculations at higher levels of theory. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Physical Activity Promotion, Beliefs, and Barriers Among Australasian Oncology Nurses.

Science.gov (United States)

Keogh, Justin W L; Pühringer, Petra; Olsen, Alicia; Sargeant, Sally; Jones, Lynnette M; Climstein, Mike

2017-03-01

To describe the physical activity (PA) promotion practices, beliefs, and barriers of Australasian oncology nurses and gain preliminary insight into how PA promotion practices may be affected by the demographics of the nurses.
. Cross-sectional survey.
. Australia and New Zealand.
. 119 registered oncology nurses.
. Self-reported online survey completed once per participant.
. Questions assessed the PA promotion beliefs (e.g., primary healthcare professionals responsible for PA promotion, treatment stage), PA benefits (e.g., primary benefits, evidence base), and PA promotion barriers of oncology nurses.
. Oncology nurses believed they were the major providers of PA advice to their patients. They promoted PA prior to, during, and post-treatment. The three most commonly cited benefits of PA for their patients were improved quality of life, mental health, and activities of daily living. Lack of time, lack of adequate support structures, and risk to patient were the most common barriers to PA promotion. Relatively few significant differences in the oncology nurses' PA promotion practices, beliefs, and barriers were observed based on hospital location or years of experience.
. Despite numerous barriers, Australasian oncology nurses wish to promote PA to their patients with cancer across multiple treatment stages because they believe PA is beneficial for their patients.
. Hospitals may need to better support oncology nurses in promoting PA to their patients and provide better referral pathways to exercise physiologists and physiotherapists.

Modeling the long-term durability of concrete barriers in the context of low-activity waste storage

Directory of Open Access Journals (Sweden)

Samson E.

2013-07-01

Full Text Available The paper investigates the long-term durability of concrete barriers in contact with a cementitious wasteform designed to immobilize low-activity nuclear waste. The high-pH pore solution of the wasteform contains high concentration level of sulfate, nitrate, nitrite and alkalis. The multilayer concrete/wasteform system was modeled using a multiionic reactive transport model accounting for coupling between species, dissolution/ precipitation reactions, and feedback effect. One of the primary objectives was to investigate the risk associated with the presence of sulfate in the wasteform on the durability of concrete. Simulation results showed that formation of expansive phases, such as gypsum and ettringite, into the concrete barrier was not extensive. Based on those results, it was not possible to conclude that concrete would be severely damaged, even after 5,000 years. Lab work was performed to provide data to validate the modeling results. Paste samples were immersed in sulfate contact solutions and analyzed to measure the impact of the aggressive environment on the material. The results obtained so far tend to confirm the numerical simulations.

Effects of reaction channels in subbarrier fusion reactions

International Nuclear Information System (INIS)

Dasso, C.H.

1984-01-01

In this lecture we consider some aspects of fusion reactions between heavy ions at bombarding energies which are below or close to that of the Coulomb barrier. This problem has been traditionally confronted with simple barrier penetration calculations. So we start with a very brief review of what we can call the ''conventional'' procedure. (orig.)

Physical activity barriers and motivators among high-risk employees.

Science.gov (United States)

Paguntalan, John C; Gregoski, Mathew

2016-11-22

Worksite wellness programs offer an ideal setting to target high-risk sedentary workers to improve health status. Lack of physical activity is associated with increased risk for coronary heart disease and mortality. Despite the risks, the number of sedentary workers is increasing. This study examined the perceived barriers and motivators for physical activity among employees at high-risk for coronary heart disease. A purposive sample of 24 high-risk workers participating in a wellness program in rural South Carolina were enrolled in the study. Qualitative data was obtained through semi-structured face-to-face interviews. Grounded theory was used to analyze qualitative data, and identify overarching themes. Physical limitations due to pain and weakness, lack of motivation, and lack of time emerged as the main barriers to physical activity. Family relationships were reported as the strongest motivator along with social support and potential health benefits. Findings highlight the unique experience of high-risk workers with physical activity. The findingsunderscore the need to design and implement effective interventions specifically designed to meet the needs of high-risk employees.

Is the perception of time pressure a barrier to healthy eating and physical activity among women?

Science.gov (United States)

Welch, Nicky; McNaughton, Sarah A; Hunter, Wendy; Hume, Clare; Crawford, David

2009-07-01

To describe the proportion of women reporting time is a barrier to healthy eating and physical activity, the characteristics of these women and the perceived causes of time pressure, and to examine associations between perceptions of time as a barrier and consumption of fruit, vegetables and fast food, and physical activity. A cross-sectional survey of food intake, physical activity and perceived causes of time pressure. A randomly selected community sample. A sample of 1580 women self-reported their food intake and their perceptions of the causes of time pressure in relation to healthy eating. An additional 1521 women self-reported their leisure-time physical activity and their perceptions of the causes of time pressure in relation to physical activity. Time pressure was reported as a barrier to healthy eating by 41% of the women and as a barrier to physical activity by 73%. Those who reported time pressure as a barrier to healthy eating were significantly less likely to meet fruit, vegetable and physical activity recommendations, and more likely to eat fast food more frequently. Women reporting time pressure as a barrier to healthy eating and physical activity are less likely to meet recommendations than are women who do not see time pressure as a barrier. Further research is required to understand the perception of time pressure issues among women and devise strategies to improve women's food and physical activity behaviours.

Theoretical study on the mechanism of the reaction of FOX-7 with OH and NO2 radicals: bimolecular reactions with low barrier during the decomposition of FOX-7

Science.gov (United States)

Zhang, Ji-Dong; Zhang, Li-Li

2017-12-01

The decomposition of 1,1-diamino-2,2-dinitroethene (FOX-7) attracts great interests, while the studies on bimolecular reactions during the decomposition of FOX-7 are scarce. This study for the first time investigated the bimolecular reactions of OH and NO2 radicals, which are pyrolysis products of ammonium perchlorate (an efficient oxidant usually used in solid propellant), with FOX-7 by computational chemistry methods. The molecular geometries and energies were calculated using the (U)B3LYP/6-31++G(d,p) method. The rate constants of the reactions were calculated by canonical variational transition state theory. We found three mechanisms (H-abstraction, OH addition to C and N atom) for the reaction of OH + FOX-7 and two mechanisms (O abstraction and H abstraction) for the reaction of NO2 + FOX-7. OH radical can abstract H atom or add to C atom of FOX-7 with barriers near to zero, which means OH radical can effectively degrade FOX-7. The O abstraction channel of the reaction of NO2 + FOX-7 results in the formation of NO3 radical, which has never been detected experimentally during the decomposition of FOX-7.

Municipal officials' perceived barriers to consideration of physical activity in community design decision making.

Science.gov (United States)

Goins, Karin Valentine; Schneider, Kristin L; Brownson, Ross; Carnoske, Cheryl; Evenson, Kelly R; Eyler, Amy; Heinrich, Katie; Litt, Jill; Lyn, Rodney; Maddock, Jay; Reed, Hannah; Tompkins, Nancy Oʼhara; Lemon, Stephenie C

2013-01-01

Built environment-focused interventions and policies are recommended as sustainable approaches for promoting physical activity. Physical activity has not traditionally been considered in land use and transportation decision making. Effective collaboration with non-public health partners requires knowledge of their perceived barriers to such consideration. This analysis sought to (a) establish prevalence estimates of selected barriers to the consideration of physical activity in community design and layout decisions and (b) describe how barrier reporting by public health officials differs from other municipal officials among a wide range of job functions and departments in a geographically diverse sample. A Web-based survey was conducted among municipal officials in 94 cities and towns with populations of at least 50 000 residents in 8 states. A total of 453 municipal officials from public health, planning, transportation/public works, community and economic development, parks and recreation, city management, and municipal legislatures in 83 cities and towns responded to the survey. Five barriers to consideration of physical activity in community design and layout were assessed. The most common barriers included lack of political will (23.5%), limited staff (20.4%), and lack of collaboration across municipal departments (16.2%). Fewer participants reported opposition from the business community or residents as barriers. Public health department personnel were more likely to report the barriers of limited staff and lack of collaboration across municipal departments than other professionals. They were also more likely to report lack of political will than city managers or mayors and municipal legislators. Barriers to increasing consideration of physical activity in decision making about community design and layout are encouragingly low. Implications for public health practice include the need to strategically increase political will despite public health staffing

Coupled modelling (transport-reaction) of the fluid-clay interactions and their feed back on the physical properties of the bentonite engineered clay barrier system; Modelisation couplee (transport - reaction) des interactions fluides - argiles et de leurs effets en retour sur les proprietes physiques de barrieres ouvragees en bentonite

Energy Technology Data Exchange (ETDEWEB)

Marty, N

2006-11-15

The originality of this work is to process feed back effects of mineralogical and chemical modifications of clays, in storage conditions, on their physical properties and therefore on their transport characteristics (porosity, molecular diffusion, permeability). These feed back effects are modelled using the KIRMAT code (Kinetic of Reaction and MAss Transfer) developed from the kinetic code KINDIS by adding the effect of water renewal in the mineral-solution reactive cells. KIRMAT resolves mass balance equations associated with mass transport together with the geochemical reactions in a 1D approach. After 100 000 years of simulated interaction at 100 C, with the fluid of the Callovo-Oxfordian geological level (COX) and with iron provided by the steel overpack corrosion, the montmorillonite of the clay barrier is only partially transformed (into illite, chlorite, saponite...). Only outer parts of the modelled profile seem to be significantly affected by smectite dissolution processes, mainly at the interface with the geological environment. The modifications of physical properties show a closure of the porosity at the boundaries of the barrier, by creating a decrease of mass transport by molecular diffusion, essentially at the interface with the iron. Permeability laws applied to this system show a decrease of the hydraulic conductivity correlated with the porosity evolution. Near the COX, the swelling pressure of the clays from the barrier decreases. In the major part of the modelled profile, the engineered clay barrier system seems to keep its initial physical properties (porosity, molecular diffusion, permeability, swelling pressure) and functionalities. (author)

A molecular dynamics study of intramolecular proton transfer reaction of malonaldehyde in solution based upon a mixed quantum-classical approximation. II. Proton transfer reaction in non-polar solvent

Science.gov (United States)

Kojima, H.; Yamada, A.; Okazaki, S.

2015-05-01

The intramolecular proton transfer reaction of malonaldehyde in neon solvent has been investigated by mixed quantum-classical molecular dynamics (QCMD) calculations and fully classical molecular dynamics (FCMD) calculations. Comparing these calculated results with those for malonaldehyde in water reported in Part I [A. Yamada, H. Kojima, and S. Okazaki, J. Chem. Phys. 141, 084509 (2014)], the solvent dependence of the reaction rate, the reaction mechanism involved, and the quantum effect therein have been investigated. With FCMD, the reaction rate in weakly interacting neon is lower than that in strongly interacting water. However, with QCMD, the order of the reaction rates is reversed. To investigate the mechanisms in detail, the reactions were categorized into three mechanisms: tunneling, thermal activation, and barrier vanishing. Then, the quantum and solvent effects were analyzed from the viewpoint of the reaction mechanism focusing on the shape of potential energy curve and its fluctuations. The higher reaction rate that was found for neon in QCMD compared with that found for water solvent arises from the tunneling reactions because of the nearly symmetric double-well shape of the potential curve in neon. The thermal activation and barrier vanishing reactions were also accelerated by the zero-point energy. The number of reactions based on these two mechanisms in water was greater than that in neon in both QCMD and FCMD because these reactions are dominated by the strength of solute-solvent interactions.

Motivation and Barriers for Leisure-Time Physical Activity in Socioeconomically Disadvantaged Women.

Science.gov (United States)

Santos, Inês; Ball, Kylie; Crawford, David; Teixeira, Pedro J

2016-01-01

The aim of this study was to examine cross-sectional and longitudinal associations between motivation and barriers for physical activity, and physical activity behavior in women living in socioeconomic disadvantage. This study also examined whether weight control intentions moderate those associations. Data from 1664 women aged 18-46 years was collected at baseline and three-year follow-up as part of the Resilience for Eating and Activity Despite Inequality study. In mail-based surveys, women reported sociodemographic and neighborhood environmental characteristics, intrinsic motivation, goals and perceived family barriers to be active, weight control intentions and leisure-time physical activity (assessed through the IPAQ-L). Linear regression models assessed the association of intrinsic motivation, goals and barriers with physical activity at baseline and follow-up, adjusting for environmental characteristics and also physical activity at baseline (for longitudinal analyses), and the moderating effects of weight control intentions were examined. Intrinsic motivation and, to a lesser extent, appearance and relaxation goals for being physically active were consistently associated with leisure-time physical activity at baseline and follow-up. Perceived family barriers, health, fitness, weight and stress relief goals were associated with leisure-time physical activity only at baseline. Moderated regression analyses revealed that weight control intentions significantly moderated the association between weight goals and leisure-time physical activity at baseline (β = 0.538, 99% CI = 0.057, 0.990) and between intrinsic motivation and leisure-time physical activity at follow-up (β = 0.666, 99% CI = 0.188, 1.145). For women actively trying to control their weight, intrinsic motivation was significantly associated with leisure-time physical activity at follow-up (β = 0.184, 99% CI = 0.097, 0.313). Results suggest that, especially in women trying to control their weight

Motivators and barriers for physical activity in the oldest old: a systematic review.

Science.gov (United States)

Baert, Veerle; Gorus, Ellen; Mets, Tony; Geerts, Christel; Bautmans, Ivan

2011-09-01

Worldwide, people engage insufficiently in physical activity, particularly subjects aged 80 years and over. For optimal life-style campaigns, knowledge of motivators and barriers for physical activity is mandatory. Given their specific needs, it is conceivable that these would be different for the oldest old compared to younger subjects. Pubmed, Web of Science and Psychinfo were systematically screened for articles reporting motivators and barriers for physical activity. Papers were excluded if data regarding elderly aged >79 years were absent. Forty-four relevant articles were included, involving a total of 28,583 subjects. Sixty one motivators and 59 barriers for physical activity in the elderly were identified, including those who are relevant for persons aged 80 years and over. Based on the results of our literature review, we recommend that when promoting physical activity in the oldest old, special attention is paid to the health benefits of physical activity, to the subject's fears, individual preferences and social support, and to constraints related to the physical environment. However, no studies were found exclusively describing people aged 80 years and over, and future research is necessary to differentiate the barriers or motivators that are specific for the oldest old from those of younger elderly. Copyright © 2011 Elsevier B.V. All rights reserved.

Decomposition mechanism of trichloroethylene based on by-product distribution in the hybrid barrier discharge plasma process

Energy Technology Data Exchange (ETDEWEB)

Han, Sang-Bo [Industry Applications Research Laboratory, Korea Electrotechnology Research Institute, Changwon, Kyeongnam (Korea, Republic of); Oda, Tetsuji [Department of Electrical Engineering, The University of Tokyo, Tokyo 113-8656 (Japan)

2007-05-15

The hybrid barrier discharge plasma process combined with ozone decomposition catalysts was studied experimentally for decomposing dilute trichloroethylene (TCE). Based on the fundamental experiment for catalytic activities on ozone decomposition, MnO{sub 2} was selected for application in the main experiments for its higher catalytic abilities than other metal oxides. A lower initial TCE concentration existed in the working gas; the larger ozone concentration was generated from the barrier discharge plasma treatment. Near complete decomposition of dichloro-acetylchloride (DCAC) into Cl{sub 2} and CO{sub x} was observed for an initial TCE concentration of less than 250 ppm. C=C {pi} bond cleavage in TCE gave a carbon single bond of DCAC through oxidation reaction during the barrier discharge plasma treatment. Those DCAC were easily broken in the subsequent catalytic reaction. While changing oxygen concentration in working gas, oxygen radicals in the plasma space strongly reacted with precursors of DCAC compared with those of trichloro-acetaldehyde. A chlorine radical chain reaction is considered as a plausible decomposition mechanism in the barrier discharge plasma treatment. The potential energy of oxygen radicals at the surface of the catalyst is considered as an important factor in causing reactive chemical reactions.

Sub-barrier capture with quantum diffusion approach

Directory of Open Access Journals (Sweden)

Scheid W.

2011-10-01

Full Text Available With the quantum diffusion approach the behavior of capture cross sections and mean-square angular momenta of captured systems are revealed in the reactions with deformed and spherical nuclei at sub-barrier energies. With decreasing bombarding energy under the barrier the external turning point of the nucleus-nucleus potential leaves the region of short-range nuclear interaction and action of friction. Because of this change of the regime of interaction, an unexpected enhancement of the capture cross section is found at bombarding energies far below the Coulomb barrier. This effect is shown its worth in the dependence of mean-square angular momentum on the bombarding energy. From the comparison of calculated capture cross sections and experimental capture or fusion cross sections the importance of quasifission near the entrance channel is demonstrated for the actinidebased reactions and reactions with medium-heavy nuclei at extreme sub-barrier energies.

Analysis of complete fusion excitation functions for 7Li+152Sm, 197Au and 209Bi reactions at around barrier energies

International Nuclear Information System (INIS)

Kharab, Rajesh; Chahal, Rajiv; Kumar, Rajiv

2017-01-01

In the present work we have analyzed the fusion excitation function for CF process using the simple Wong’s formula in conjunction with the energy dependent Woods-Saxon potential (EDWSP) in near barrier energy region for 7 Li+ 152 Sm, 197 Au and 209 Bi reactions

Tuning Catalytic Performance through a Single or Sequential Post-Synthesis Reaction(s) in a Gas Phase

Energy Technology Data Exchange (ETDEWEB)

Shan, Junjun [Department; Department; Zhang, Shiran [Department; Department; Choksi, Tej [Department; Nguyen, Luan [Department; Department; Bonifacio, Cecile S. [Department; Li, Yuanyuan [Department; Zhu, Wei [Department; Department; College; Tang, Yu [Department; Department; Zhang, Yawen [College; Yang, Judith C. [Department; Greeley, Jeffrey [Department; Frenkel, Anatoly I. [Department; Tao, Franklin [Department; Department

2016-12-05

Catalytic performance of a bimetallic catalyst is determined by geometric structure and electronic state of the surface or even the near-surface region of the catalyst. Here we report that single and sequential postsynthesis reactions of an as-synthesized bimetallic nanoparticle catalyst in one or more gas phases can tailor surface chemistry and structure of the catalyst in a gas phase, by which catalytic performance of this bimetallic catalyst can be tuned. Pt–Cu regular nanocube (Pt–Cu RNC) and concave nanocube (Pt–Cu CNC) are chosen as models of bimetallic catalysts. Surface chemistry and catalyst structure under different reaction conditions and during catalysis were explored in gas phase of one or two reactants with ambient-pressure X-ray photoelectron spectroscopy (AP-XPS) and extended X-ray absorption fine structure (EXAFS) spectroscopy. The newly formed surface structures of Pt–Cu RNC and Pt–Cu CNC catalysts strongly depend on the reactive gas(es) used in the postsynthesis reaction(s). A reaction of Pt–Cu RNC-as synthesized with H2 at 200 °C generates a near-surface alloy consisting of a Pt skin layer, a Cu-rich subsurface, and a Pt-rich deep layer. This near-surface alloy of Pt–Cu RNC-as synthesized-H2 exhibits a much higher catalytic activity in CO oxidation in terms of a low activation barrier of 39 ± 4 kJ/mol in contrast to 128 ± 7 kJ/mol of Pt–Cu RNC-as synthesized. Here the significant decrease of activation barrier demonstrates a method to tune catalytic performances of as-synthesized bimetallic catalysts. A further reaction of Pt–Cu RNC-as synthesized-H2 with CO forms a Pt–Cu alloy surface, which exhibits quite different catalytic performance in CO oxidation. It suggests the capability of generating a different surface by using another gas. The capability of tuning surface chemistry and structure of bimetallic catalysts was also demonstrated in restructuring of Pt–Cu CNC-as synthesized.

Study on characteristics of high frequency dielectric barrier discharge for the removal of organic pollutant adsorbed on activated carbon

Energy Technology Data Exchange (ETDEWEB)

Qu, G.Z.; Li, G.F. [Dalian Univ. of Technology, Dalian (China). Inst. of Electrostatics and Special Power; Li, J.; Lu, N.; Wu, Y.; Li, D. [Dalian Univ. of Technology, Dalian (China). Inst. of Electrostatics and Special Power; Key Lab of Industrial Ecology and Environmental Engineering, Ministry of Education, Dalian (China)

2010-07-01

Advanced oxidation technologies such as photocatalysis, electrochemical degradation, Fenton oxidation, hydrogen peroxide oxidation, and plasma oxidation are increasingly being used to degrade refractory biodegradable organic contaminants. The plasma oxidation method has the advantage of direct in situ production of multiple types of high-reactive chemical species, including molecules and radicals that facilitate the degradation reaction. In addition, plasma oxidation does not produce any secondary pollution. Compared to other plasma technologies, the dielectric barrier discharge (DBD) plasma has been considered as a promising technology for removing toxic compounds because of its stability and its treatability property of biologically recalcitrant compounds in wastewater. However, the energy efficiency of DBD requires improvement for economic reasons. This paper reported on an experimental study that investigated the electrical characteristics of a parallel plate DBD reactor using a high frequency power supply for the removal of pentachlorophenol (PCP) adsorbed on activated carbon (AC). This study examined the effects of AC with different mass on discharge characteristics and compared the voltage and current waveforms, and discharge images of DBD reactors with different dielectric configurations. When the DBD reactor filled with AC, the applied voltage of discharge decreased regardless of the DBD reactor configuration in terms of having a single barrier or two barriers. The discharge characteristics had no significant change with AC mass increasing. The discharge images and current waveforms showed that DBD reactor configuration consisting of two dielectrics is more homogeneous and stable than the one consisting of a single dielectric. Under the same electric field condition, the degradation efficiency of PCP in two barriers reactor is higher than that in single barrier reactor. It was concluded that the findings from this study may be instrumental in treating

Calcium-Magnesium-Alumino-Silicates (CMAS) Reaction Mechanisms and Resistance of Advanced Turbine Environmental Barrier Coatings for SiC/SiC Ceramic Matrix Composites

Science.gov (United States)

Zhu, Dongming; Costa, Gustavo; Harder, Bryan J.; Wiesner, Valerie L.; Hurst, Janet B.; Puleo, Bernadette J.

2017-01-01

Environmental barrier coatings (EBCs) and SiC/SiC ceramic matrix composites (CMCs) systems will play a crucial role in future turbine engines for hot-section component applications because of their ability to significantly increase engine operating temperatures, reduce engine weight and cooling requirements. The development of prime-reliant environmental barrier coatings is an essential requirement to enable the applications of the 2700-3000 F EBC - CMC systems. This presentation primarily focuses on the reaction mechanisms of advanced NASA environmental barrier coating systems, when in contact with Calcium-Magnesium Alumino-Silicates (CMAS) at high temperatures. Advanced oxide-silicate defect cluster environmental barrier coatings are being designed for ultimate balanced controls of the EBC temperature capability and CMAS reactivity, thus improving the CMAS resistance. Further CMAS mitigation strategies are also discussed.

Physical activity preferences, motivators, barriers and attitudes of adults with mental illness.

Science.gov (United States)

Chapman, Justin J; Fraser, Sarah J; Brown, Wendy J; Burton, Nicola W

2016-10-01

Adults with mental illness may have specific attitudes toward physical activity (PA). To assess the PA attitudes of non-institutionalised adults with mental illness, and associations with psychological distress. Participants completed questionnaires on activity preferences (type, context and sources of support), motivators, barriers and attitudes toward personal training (PT). Relationships between responses and distress were assessed using logistic regressions. One-hundred forty-two participants completed the questionnaires. PA context preferences included activities done close to home, outdoors, with professional instruction, with people of the same ability, as part of a healthy lifestyle program and with a social component. The most commonly endorsed source of support was an exercise instructor. Most respondents had never received PT; however, PT had high acceptability. Common barriers included poor physical and mental health, and lack of money. Distress was positively associated with barriers of poor mental health, tiredness, disorganisation, exhaustion and being shy/embarrassed (p ≤ 0.001). Local outdoor walking groups that include social and healthy lifestyle components, and that are led by an exercise instructor who can provide support for overcoming barriers, may best meet PA interests of this group. PT could be an acceptable method for offering individualised support.

Perceived Barriers to Healthy Eating and Physical Activity Among Participants in a Workplace Obesity Intervention.

Science.gov (United States)

Stankevitz, Kayla; Dement, John; Schoenfisch, Ashley; Joyner, Julie; Clancy, Shayna M; Stroo, Marissa; Østbye, Truls

2017-08-01

To characterize barriers to healthy eating (BHE) and physical activity (BPA) among participants in a workplace weight management intervention. Steps to health participants completed a questionnaire to ascertain barriers to physical activity and healthy eating faced. Exploratory factor analysis was used to determine the factor structure for BPA and BHE. The relationships of these factors with accelerometer data and dietary behaviors were assessed using linear regression. Barriers to physical activity included time constraints and lack of interest and motivation, and to healthy eating, lack of self-control and convenience, and lack of access to healthy foods. Higher BHE correlated with higher sugary beverage intake but not fruit and vegetable and fat intake. To improve their effectiveness, workplace weight management programs should consider addressing and reducing barriers to healthy eating and physical activity.

Barriers, activities and participation: Incorporating ICF into service planning datasets.

LENUS (Irish Health Repository)

O'Donovan, MA

2009-05-21

Purpose. Guided by the World Health Organization\\'s International Classification of Functioning, Disability and Health (ICF), a measure of activity and participation (MAP) was developed and incorporated into the National Physical and Sensory Disability Database in Ireland. The aims of this article are to investigate and explore the relationship between the barriers, participation restriction and functioning levels experienced by people with disabilities. Method. Seven thousand five hundred and sixty-two personal interviews with people meeting specific eligibility criteria for registering onto the database were conducted across four health service executive regions in Ireland. Results. Overall, differences in barriers, participation restriction and activity limitations experienced by people with different types of disabilities were found to be significant. Furthermore, low functioning and experience of barriers were indicators of participation restriction. Conclusions. This article has shown that elements of the ICF have been successfully operationalised in a service planning tool through the development of the MAP. This provides a more holistic view of disability and will enable the impact of service interventions to be measured over time.

Perceived barriers to and facilitators of physical activity in young adults with childhood-onset physical disabilities.

Science.gov (United States)

Buffart, Laurien M; Westendorp, Tessa; van den Berg-Emons, Rita J; Stam, Henk J; Roebroeck, Marij E

2009-11-01

To explore the main barriers to and facilitators of physical activity in young adults with childhood-onset physical disabilities. Qualitative study using focus groups. Sixteen persons (12 men and 4 women) aged 22.4 (standard deviation 3.4) years, of whom 50% were wheelchair-dependent, participated in the study. Eight were diagnosed with myelomeningocele, 4 with cerebral palsy, 2 with acquired brain injury and 2 with rheumatoid arthritis. Three focus group sessions of 1.5 h were conducted using a semi-structured question route to assess perceived barriers to and facilitators of physical activity. Tape recordings were transcribed verbatim and content analysed. According to the Physical Activity for People with a Physical Disability model, barriers and facilitators were subdivided into personal factors and environmental factors. Participants reported several barriers related to attitude and motivation. In addition, lack of energy, existing injury or fear of developing injuries or complications, limited physical activity facilities, and lack of information and knowledge, appeared to be barriers to physical activity. Fun and social contacts were mentioned as facilitators of engaging in physical activity, as well as improved health and fitness. Young adults with childhood-onset physical disabilities perceived various personal and environmental factors as barriers to or facilitators of physical activity. These should be taken into account when developing interventions to promote physical activity in this population.

Extracellular adenosine-induced Rac1 activation in pulmonary endothelium: Molecular mechanisms and barrier-protective role.

Science.gov (United States)

Kovacs-Kasa, Anita; Kim, Kyung Mi; Cherian-Shaw, Mary; Black, Stephen M; Fulton, David J; Verin, Alexander D

2018-08-01

We have previously shown that Gs-coupled adenosine receptors (A2a) are primarily involved in adenosine-induced human pulmonary artery endothelial cell (HPAEC) barrier enhancement. However, the downstream events that mediate the strengthening of the endothelial cell (EC) barrier via adenosine signaling are largely unknown. In the current study, we tested the overall hypothesis that adenosine-induced Rac1 activation and EC barrier enhancement is mediated by Gs-dependent stimulation of cAMP-dependent Epac1-mediated signaling cascades. Adenoviral transduction of HPAEC with constitutively-active (C/A) Rac1 (V12Rac1) significantly increases transendothelial electrical resistance (TER) reflecting an enhancement of the EC barrier. Conversely, expression of an inactive Rac1 mutant (N17Rac1) decreases TER reflecting a compromised EC barrier. The adenosine-induced increase in TER was accompanied by activation of Rac1, decrease in contractility (MLC dephosphorylation), but not Rho inhibition. Conversely, inhibition of Rac1 activity attenuates adenosine-induced increase in TER. We next examined the role of cAMP-activated Epac1 and its putative downstream targets Rac1, Vav2, Rap1, and Tiam1. Depletion of Epac1 attenuated the adenosine-induced Rac1 activation and the increase in TER. Furthermore, silencing of Rac1 specific guanine nucleotide exchange factors (GEFs), Vav2 and Rap1a expression significantly attenuated adenosine-induced increases in TER and activation of Rac1. Depletion of Rap1b only modestly impacted adenosine-induced increases in TER and Tiam1 depletion had no effect on adenosine-induced Rac1 activation and TER. Together these data strongly suggest that Rac1 activity is required for adenosine-induced EC barrier enhancement and that the activation of Rac1 and ability to strengthen the EC barrier depends, at least in part, on cAMP-dependent Epac1/Vav2/Rap1-mediated signaling. © 2017 Wiley Periodicals, Inc.

Barriers, Motivations, and Preferences for Physical Activity Among Female African American Older Adults

Directory of Open Access Journals (Sweden)

Neha P. Gothe PhD

2016-11-01

Full Text Available According to the Centers for Disease Control and Prevention, less than 11% of adults more than the age of 65 meet the 2008 Physical Activity Guidelines for Americans. Among minority populations, only 5% of non-Hispanic Black older adults met the guidelines. Given our limited understanding of psychosocial and environmental factors that affect physical activity participation in these groups, the purpose of our focus groups was to investigate barriers, motivators, and preferences of physical activity for community-dwelling African American older adults. Three focus groups were conducted with female African American older adults ( N = 20. Questions posed to each focus group targeted motivations and barriers toward physical activity as well as their preferences for physical activity. The motivations included perceived health benefits of physical activity, social support, and enjoyment associated with engagement in physical activity. Prominent barriers included time and physical limitations, peer pressure and family responsibilities, and weather and poor neighborhood conditions. Group activities involving a dance component and novel exercises such as tai-chi or yoga were preferred choices. These findings should be taken into consideration when designing and implementing research or community physical activity programs for female African American older adults.

Barriers, Motivations, and Preferences for Physical Activity Among Female African American Older Adults.

Science.gov (United States)

Gothe, Neha P; Kendall, Bradley J

2016-01-01

According to the Centers for Disease Control and Prevention, less than 11% of adults more than the age of 65 meet the 2008 Physical Activity Guidelines for Americans. Among minority populations, only 5% of non-Hispanic Black older adults met the guidelines. Given our limited understanding of psychosocial and environmental factors that affect physical activity participation in these groups, the purpose of our focus groups was to investigate barriers, motivators, and preferences of physical activity for community-dwelling African American older adults. Three focus groups were conducted with female African American older adults ( N = 20). Questions posed to each focus group targeted motivations and barriers toward physical activity as well as their preferences for physical activity. The motivations included perceived health benefits of physical activity, social support, and enjoyment associated with engagement in physical activity. Prominent barriers included time and physical limitations, peer pressure and family responsibilities, and weather and poor neighborhood conditions. Group activities involving a dance component and novel exercises such as tai-chi or yoga were preferred choices. These findings should be taken into consideration when designing and implementing research or community physical activity programs for female African American older adults.

Activated barrier for protection of special nuclear materials in vital areas

International Nuclear Information System (INIS)

Timm, R.E.; Miranda, J.E.; Reigle, D.L.; Valente, A.D.

1984-01-01

The Argonne National Laboratory and Sandia National Laboratory have recently installed an activated barrier, the Access Denial System (ADS) for the upgrade of safeguards of special nuclear materials. The technology of this system was developed in the late 70's by Sandia National Laboratory-Albuquerque. The installation was the first for the Department of Energy. Subsequently, two additional installations have been completed. The Access Denial System, combined with physical restraints, provide the system delay. The principal advantages of the activated barrier are: (1) it provides an order of magnitude improvement in delay over that of a fixed barrier, (2) it can be added to existing vital areas with a minimum of renovations, (3) existing operations are minimally impacted, and (4) health and safety risks are virtually nonexistent. Hardening of the vital areas using the ADS was accomplished in a cost-effective manner. 3 references, 1 figure, 1 table

Towards a converged barrier height for the entrance channel transition state of the N( 2D) + CH 4 reaction and its implication for the chemistry in Titan's atmosphere

Science.gov (United States)

Ouk, Chanda-Malis; Zvereva-Loëte, Natalia; Bussery-Honvault, Béatrice

2011-10-01

The N( 2D) + CH 4 reaction appears to be a key reaction for the chemistry of Titan's atmosphere, opening the door to nitrile formation as recently observed by the Cassini-Huygens mission. Faced to the controversy concerning the existence or not of a potential barrier for this reaction, we have carried out accurate ab initio calculations by means of multi-state multi-reference configuration interaction (MS-MR-SDCI) method. These calculations have been partially corrected for the size-consistency errors (SCE) by Davidson, Pople or AQCC corrections. We suggest a barrier height of 3.86 ± 0.84 kJ/mol, including ZPE, for the entrance transition state, in good agreement with the experimental value. Its implication in Titan's atmopsheric chemistry is discussed.

Self-reported physical activity in patients on chronic hemodialysis: correlates and barriers.

Science.gov (United States)

Bossola, Maurizio; Pellu, Valentina; Di Stasio, Enrico; Tazza, Luigi; Giungi, Stefania; Nebiolo, Pier Eugenio

2014-01-01

The knowledge of the barriers that are associated with decreased physical activity (PA) in patients on chronic hemodialysis (PCH) may be of primary importance for the nephrologists. Thus, we aimed to assess the barriers associated with the absent or reduced PA in PCH of a Mediterranean country. Patients were invited to answer the question 'How often do you exercise during your leisure time?'. Also, patients included in the study were asked to answer questions regarding barriers to physical activity lower than desired. We studied 105 patients. Forty (38.1%) patients reported to never exercise, 6 (5.7%) reported to exercise less than once/week, 4 (3.8%) once/week, 23 (21.9%) two to three times/week, 12 (11.4%) four to five times/week and 20 (19%) daily. Overall, 46 (43.8%) patients never exercised or exercised less than once/week ('inactive') and 59 (56.2%) did exercise more often ('active'). At the multivariate analysis, reduced walking ability, fatigue on the non-dialysis days, and shortness of breath were independently and negatively associated with PA. The same results were found when the reduced model of the multivariate logistic backward regression was built introducing in the model also clinical and laboratory variables. In PCH, fatigue on the non-dialysis days, reduced walking ability, and shortness of breath are barriers independently associated to decreased PA. Knowledge about the causes and mechanisms that generate these barriers has to be acquired. © 2014 S. Karger AG, Basel.

Perceived benefits and barriers of physical activity: A social marketing formative study.

Science.gov (United States)

Rundle-Thiele, Sharyn; Kubacki, Krzysztof; Gruneklee, Naomi

2016-01-01

The aim of this study was to gain formative research insights that can be used to design social marketing campaigns. One thousand four hundred fifty-nine people participated in an online survey. Factor analysis was undertaken to establish perceived benefits and barriers, and indexes were created for barriers, benefits, and healthy living knowledge. Four attitude groups were formed and analysis of variance was undertaken to explore group differences. Consumers with high perceived barriers report less physical activity than consumers with low perceived barriers to exercise. The current study provides evidence to suggest that exchange theory can offer important insights to inform social marketing intervention planning.

Optimal control of a Cope rearrangement by coupling the reaction path to a dissipative bath or a second active mode

International Nuclear Information System (INIS)

Chenel, A.; Meier, C.; Dive, G.; Desouter-Lecomte, M.

2015-01-01

We compare the strategy found by the optimal control theory in a complex molecular system according to the active subspace coupled to the field. The model is the isomerization during a Cope rearrangement of Thiele’s ester that is the most stable dimer obtained by the dimerization of methyl-cyclopentadienenylcarboxylate. The crudest partitioning consists in retaining in the active space only the reaction coordinate, coupled to a dissipative bath of harmonic oscillators which are not coupled to the field. The control then fights against dissipation by accelerating the passage across the transition region which is very wide and flat in a Cope reaction. This mechanism has been observed in our previous simulations [Chenel et al., J. Phys. Chem. A 116, 11273 (2012)]. We compare here, the response of the control field when the reaction path is coupled to a second active mode. Constraints on the integrated intensity and on the maximum amplitude of the fields are imposed limiting the control landscape. Then, optimum field from one-dimensional simulation cannot provide a very high yield. Better guess fields based on the two-dimensional model allow the control to exploit different mechanisms providing a high control yield. By coupling the reaction surface to a bath, we confirm the link between the robustness of the field against dissipation and the time spent in the delocalized states above the transition barrier

The Atmospherically Important Reaction of Hydroxyl Radicals with Methyl Nitrate: A Theoretical Study Involving the Calculation of Reaction Mechanisms, Enthalpies, Activation Energies, and Rate Coefficients.

Science.gov (United States)

Ng, Maggie; Mok, Daniel K W; Lee, Edmond P F; Dyke, John M

2017-09-07

A theoretical study, involving the calculation of reaction enthalpies, activation energies, mechanisms, and rate coefficients, was made of the reaction of hydroxyl radicals with methyl nitrate, an important process for methyl nitrate removal in the earth's atmosphere. Four reaction channels were considered: formation of H 2 O + CH 2 ONO 2 , CH 3 OOH + NO 2 , CH 3 OH + NO 3 , and CH 3 O + HNO 3 . For all channels, geometry optimization and frequency calculations were performed at the M06-2X/6-31+G** level, while relative energies were improved at the UCCSD(T*)-F12/CBS level. The major channel is found to be the H abstraction channel, to give the products H 2 O + CH 2 ONO 2 . The reaction enthalpy (ΔH 298 K RX ) of this channel is computed as -17.90 kcal mol -1 . Although the other reaction channels are also exothermic, their reaction barriers are high (>24 kcal mol -1 ), and therefore these reactions do not contribute to the overall rate coefficient in the temperature range considered (200-400 K). Pathways via three transition states were identified for the H abstraction channel. Rate coefficients were calculated for these pathways at various levels of variational transition state theory including tunneling. The results obtained are used to distinguish between two sets of experimental rate coefficients, measured in the temperature range of 200-400 K, one of which is approximately an order of magnitude greater than the other. This comparison, as well as the temperature dependence of the computed rate coefficients, shows that the lower experimental values are favored. The implications of the results to atmospheric chemistry are discussed.

Solvent effect on the degree of (a)synchronicity in polar Diels-Alder reactions from the perspective of the reaction force constant analysis.

Science.gov (United States)

Yepes, Diana; Martínez-Araya, Jorge I; Jaque, Pablo

2017-12-29

In this work, we computationally evaluated the influence of six different molecular solvents, described as a polarizable continuum model at the M06-2X/6-31+G(d,p) level, on the activation barrier/reaction rate, overall energy change, TS geometry, and degree of (a)synchronicity of two concerted Diels-Alder cycloadditions of acrolein (R1) and its complex with Lewis acid acrolein···BH 3 (R2) to cyclopentadiene. In gas-phase, we found that both exothermicity and activation barrier are only reduced by about 2.0 kcal mol -1 , and the asynchronicity character of the mechanism is accentuated when BH 3 is included. An increment in the solvent's polarity lowers the activation energy of R1 by 1.3 kcal mol -1 , while for R2 the reaction rate is enhanced by more than 2000 times at room temperature (i.e., the activation energy decreases by 4.5 kcal mol -1 ) if the highest polar media is employed. Therefore, a synergistic effect is achieved when both external agents, i.e., Lewis acid catalyst and polar solvent, are included together. This effect was ascribed to the ability of the solvent to favor the encounter between cyclopentadiene and acrolein···BH 3 . This was validated by the asymmetry of the TS which becomes highly pronounced when either both or just BH 3 is considered or the solvent's polarity is increased. Finally, the reaction force constant κ(ξ) reveals that an increment in the solvent's polarity is able to turn a moderate asynchronous mechanism of the formation of the new C-C σ-bonds into a highly asynchronous one. Graphical abstract A synergistic effect is achieved when both external agents, i.e., Lewis acid catalyst and polar solvent, are included together: lowered energy barriers and increased asynchronicities.

Performance of engineered barriers for low-level waste

International Nuclear Information System (INIS)

Taplin, D.; Claridge, F.B.

1987-09-01

Geotechnical Resources Ltd., in association with Komex Consultants Ltd., was retained to collect, synthesize and evaluate the available information on the long term performance of engineered barriers for low-level radioactive wastes disposed in Canada. Literature was researched from Canadian, United States and European sources. A variety of barrier materials were assessed in the study and included natural clays, concrete and cement, metals, bentonite-sand admixes, bitumen and bituminous admixes, soil cement and polymeric membranes. The generalized geological and geotechnical conditions encountered within the soil and rock host media currently under consideration for disposal sites in southern Ontario were also summarized. Both internal barriers, or buffers, to immobilize the waste material and reduce radionuclide mobility, as well as external barriers to limit the migration of contaminants were examined. Microbial activities within the waste forms were analyzed, including cellulose degradation, methanogenesis and bicarbonate and organic reactions. Microbial interactions with the various engineered barrier materials under consideration were also assessed. Finally, the anticipated long term performances of the respective barrier materials under consideration were evaluated, along with the general suitability of the geological host media being proposed for disposal sites

Predictors of perceived barriers to physical activity in the general adult population: a cross-sectional study.

Science.gov (United States)

Herazo-Beltrán, Yaneth; Pinillos, Yisel; Vidarte, José; Crissien, Estela; Suarez, Damaris; García, Rafael

The perception of personal barriers to physical activity varies according to the sociodemographic characteristics of individuals. To determine the predictors of the perception of barriers to physical activity in the adult population. A cross-sectional study with 1066 adult women and 1036 adult men. The sociodemographic variables (age, gender, marital status, socioeconomic level, level of education), the perception of barriers that do not allow performance of physical activity (i.e. lack of time, social support, energy, motivation, skill, resources, and fear of injury during practice); and the level of physical activity through the International Physical Activity Questionnaire in its short-form version were evaluated. Individuals from low socioeconomic level (1 and 2) have higher risks of perceiving barriers such as lack of motivation [OR 1.76 (95% CI (1.4-2.1))] and lack of resources [OR 1.37 (95% CI (1.1-1.6))]; individuals with partners did not perceive the lack of social support [OR 0.29 (95% CI (0.2-0.4))] and lack of motivation [OR 0.54 (95% CI (0.4-0.7))] as barriers to physical activity. Individuals with low schooling perceived lack of social support [OR 3.81 (95% CI (3-4.7))], lack of resources [OR 2.78 (95% CI (2.2-3.3))], and fear of injury [OR 2.70 (95% CI (2.2-3.3))] as barrier to physical activity. Factors such as socioeconomic level, marital status, level of education, and self-perception of health are predictors of barriers to physical activity. Copyright © 2017 Associação Brasileira de Pesquisa e Pós-Graduação em Fisioterapia. Publicado por Elsevier Editora Ltda. All rights reserved.

Perceived barriers by university students in the practice of physical activities.

Science.gov (United States)

Gómez-López, Manuel; Gallegos, Antonio Granero; Extremera, Antonio Baena

2010-01-01

The main goal of this research is to study in detail the main characteristics of university students in order to find out the reasons why they have adopted an inactive lifestyle. In order to do so, a questionnaire on the analysis of sports habits and lifestyle was given to 323 students. They were taken from a representative sample of 1834 students. These 323 students had pointed out at the moment of the fieldwork, not having practiced any sport in their spare time. Our findings point out that there are diverse reasons for this. On one hand, reasons referred to as external barriers such as lack of time, on the other hand, internal barriers such as not liking the physical activity, not seeing its practicality or usefulness, feeling lazy or with apathy, or thinking that they are not competent in this type of activities. Other reasons such as the lack of social support are grouped within the external barriers. Finally, it is important to stress that there are also differences based on gender with respect to motivation. Key pointsExternal barriers prevail in university students. The lack of time is among the most highlighted ones.Statistically significant results have been found regarding the gender variable.The results are very important since they are considered to be valuable information for university institutions when guiding and diversifying their offer of physical and sport activities. Also as a guide in the design of support policies and national sport management guidelines.

Temperature dependence of muonium reaction rates in the gas phase

International Nuclear Information System (INIS)

Fleming, D.G.; Garner, D.M.; Mikula, R.J.; British Columbia Univ., Vancouver

1981-01-01

A study of the temperature dependence of reaction rates has long been an important tool in establishing reaction pathways in chemical reactions. This is particularly true for the reactions of muonium (in comparison with those of hydrogen) since a measurement of the activation energy for chemical reaction is sensitive to both the height and the position of the potential barrier in the reaction plane. For collision controlled reactions, on the other hand, the reaction rate is expected to exhibit a weak T 1 sup(/) 2 dependence characteristic of the mean collision velocity. These concepts are discussed and their effects illustrated in a comparison of the chemical and spin exchange reaction rates of muonium and hydrogen in the temperature range approx.300-approx.500 K. (orig.)

"What I Wish You Knew": Social Barriers toward Physical Activity in Youth with Congenital Heart Disease (CHD)

Science.gov (United States)

Moola, Fiona; Fusco, Caroline; Kirsh, Joel A.

2011-01-01

Despite the benefits of physical activity for youth with congenital heart disease (CHD), most patients are inactive. Although literature has addressed medical and psychological barriers to participation, little is known about the social barriers that youth encounter. This qualitative study explored sociocultural barriers to physical activity from…

Interpretation of quasi-elastic barrier distributions for weakly bound systems

International Nuclear Information System (INIS)

Monteiro, D.S.; Gomes, P.R.S.; Lubian, J.

2009-01-01

Full text: We verify that quasi-elastic (elastic + inelastic) backscattering barrier distributions for weakly bound systems do not strictly correspond to fusion barrier distributions, but rather to reaction threshold distribution, as proposed by Zagrebaev in a recent paper concerning very heavy systems. In this work, we investigate whether Zagrebaevs interpretation is valid by comparing experimental results obtained in two very recent works with the 6 Li + 144 Sm system. Monteiro et al derived the quasi-elastic barrier distribution (or reaction threshold distribution, following Zagrebaevs interpretation) by adding elastic and inelastic backscattering for this system. Rath et al obtained fusion barrier distribution for the same system from the measured complete fusion cross section for the same system. We conclude that the quasi-elastic barrier distributions can be associated with fusion barrier distributions only in situations where there are no relevant reaction channels apart from fusion. This is not the situation for very heavy nor for weakly bound systems. (author)

Barriers and facilitators to being physically active on a rural U.S. Northern Plains American Indian reservation.

Science.gov (United States)

Jahns, Lisa; McDonald, Leander R; Wadsworth, Ann; Morin, Charles; Liu, Yan

2014-11-21

The objective of the present study was to identify barriers to and facilitators of physical activity among American Indian adults living on a rural, U.S. Northern Plains reservation using the nominal group technique (NGT). NGT is a method of data generation and interpretation that combines aspects of qualitative (free generation of responses) and quantitative (systematic ranking of responses) methodologies. Adults participated in one of two NGT sessions asking about either barriers to (n = 6), or facilitators of (n = 5), being physically active. Participants nominated and ranked 21 barriers and 18 facilitators. Barriers indicated lack of knowledge of how to fit physical activity into a daily schedule, work, caring for family members, and prioritizing sedentary pursuits. Other responses included environmental barriers such as lack of access and transportation to a gym, unsafe walking conditions, and inclement weather. Facilitators to following recommendations included knowledge of health benefits of physical activity and the perception of physical activity as enjoyable, including feeling good when working out. Environmental facilitators included being outdoors walking and biking as well as parks and exercise facilities. Responses provided direction for locally designed community-based programs to promote facilitators and decrease barriers to individual's engagement in physical activity.

Perceived Barriers to Healthy Eating and Physical Activity among Adolescents in Seven Arab Countries: A Cross-Cultural Study

Directory of Open Access Journals (Sweden)

Abdulrahman O. Musaiger

2013-01-01

Full Text Available Objective. To highlight the perceived personal, social, and environmental barriers to healthy eating and physical activity among Arab adolescents. Method. A multistage stratified sampling method was used to select 4698 students aged 15–18 years (2240 males and 2458 females from public schools. Seven Arab counties were included in the study, namely, Algeria, Jordan, Kuwait, Libya, Palestine, Syria, and the United Arab Emirates. Self-reported questionnaire was used to list the barriers to healthy eating and physical activity facing these adolescents. Results. It was found that lack of information on healthy eating, lack of motivation to eat a healthy diet, and not having time to prepare or eat healthy food were the main barriers to healthy eating among both genders. For physical activity, the main barriers selected were lack of motivation to do physical activity, less support from teachers, and lack of time to do physical activity. In general, females faced more barriers to physical activity than males in all countries included. There were significant differences between males and females within each country and among countries for most barriers. Conclusion. Intervention programmes to combat obesity and other chronic noncommunicable diseases in the Arab world should include solutions to overcome the barriers to weight maintenance, particularly the sociocultural barriers to practising physical activity.

Removal of alachlor, diuron and isoproturon in water in a falling film dielectric barrier discharge (DBD) reactor combined with adsorption on activated carbon textile: Reaction mechanisms and oxidation by-products.

Science.gov (United States)

Vanraes, Patrick; Wardenier, Niels; Surmont, Pieter; Lynen, Frederic; Nikiforov, Anton; Van Hulle, Stijn W H; Leys, Christophe; Bogaerts, Annemie

2018-05-03

A falling film dielectric barrier discharge (DBD) plasma reactor combined with adsorption on activated carbon textile material was optimized to minimize the formation of hazardous oxidation by-products from the treatment of persistent pesticides (alachlor, diuron and isoproturon) in water. The formation of by-products and the reaction mechanism was investigated by HPLC-TOF-MS. The maximum concentration of each by-product was at least two orders of magnitude below the initial pesticide concentration, during the first 10 min of treatment. After 30 min of treatment, the individual by-product concentrations had decreased to values of at least three orders of magnitude below the initial pesticide concentration. The proposed oxidation pathways revealed five main oxidation steps: dechlorination, dealkylation, hydroxylation, addition of a double-bonded oxygen and nitrification. The latter is one of the main oxidation mechanisms of diuron and isoproturon for air plasma treatment. To our knowledge, this is the first time that the formation of nitrificated intermediates is reported for the plasma treatment of non-phenolic compounds. Copyright © 2018 Elsevier B.V. All rights reserved.

The role of perceived barriers and objectively measured physical activity in adults aged 65-100.

Science.gov (United States)

Gellert, Paul; Witham, Miles D; Crombie, Iain K; Donnan, Peter T; McMurdo, Marion E T; Sniehotta, Falko F

2015-05-01

to test the predictive utility of perceived barriers to objectively measured physical activity levels in a stratified sample of older adults when accounting for social-cognitive determinants proposed by the Theory of Planned Behaviour (TPB), and economic and demographic factors. data were analysed from the Physical Activity Cohort Scotland survey, a representative and stratified (65-80 and 80+ years; deprived and affluent) sample of 584 community-dwelling older people, resident in Tayside, Scotland. Physical activity was measured objectively by accelerometry. perceived barriers clustered around the areas of poor health, lack of interest, lack of safety and lack of access. Perceived poor health and lack of interest, but not lack of access or concerns about personal safety, predicted physical activity after controlling for demographic, economic and TPB variables. perceived person-related barriers (poor health and lack of interest) seem to be more strongly associated with physical activity levels than perceived environmental barriers (safety and access) in a large sample of older adults. Perceived barriers are modifiable and may be a target for future interventions. © The Author 2015. Published by Oxford University Press on behalf of the British Geriatrics Society. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Perceived barriers to leisure-time physical activity during pregnancy: A literature review of quantitative and qualitative evidence.

Science.gov (United States)

Coll, Carolina V N; Domingues, Marlos R; Gonçalves, Helen; Bertoldi, Andréa D

2017-01-01

Identify perceived barriers to leisure-time physical activity during pregnancy to inform future interventions aimed at improving physical activity levels in pregnancy. PubMed/Medline and Web of Science databases were systematically searched using a reference period between 1986 and January/2016. A comprehensive search strategy was developed combining the following keywords: (barriers OR constraints OR perceptions OR attitudes) AND (physical activity OR exercise OR motor activity) AND (pregnancy OR pregnant women OR antenatal OR prenatal). Thematic synthesis was conducted to analyze the data. A socioecological model was used to categorize the reported barriers. Twelve quantitative studies and 14 qualitative studies were included. Barriers belonging to the intrapersonal level of the socioecological model were the most reported in the studies and were categorized in five themes as follows: (1) Pregnancy-related symptoms and limitations; (2) Time constraints; (3) Perceptions of already being active, (4) Lack of motivation and (5) Mother-child safety concerns. At the interpersonal level, barriers were coded into two descriptive themes: (1) Lack of advice and information and (2) Lack of social support. Two other themes were used to summarize Environmental, Organizational and Policy barriers: (1) Adverse weather and (2) Lack of resources. A range of relevant barriers to leisure-time physical-activity engagement during pregnancy were identified in this literature review. Pregnancy-related symptoms and limitations barriers were the most reported in studies, regardless of study design. Mother-child safety concerns, lack of advice/information and lack of social support were also important emphasized pregnancy-related barriers to be targeted in future interventions. Copyright © 2016 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

Reaction energetics on long-range corrected density functional theory: Diels-Alder reactions.

Science.gov (United States)

Singh, Raman K; Tsuneda, Takao

2013-02-15

The possibility of quantitative reaction analysis on the orbital energies of long-range corrected density functional theory (LC-DFT) is presented. First, we calculated the Diels-Alder reaction enthalpies that have been poorly given by conventional functionals including B3LYP functional. As a result, it is found that the long-range correction drastically improves the reaction enthalpies. The barrier height energies were also computed for these reactions. Consequently, we found that dispersion correlation correction is also crucial to give accurate barrier height energies. It is, therefore, concluded that both long-range exchange interactions and dispersion correlations are essentially required in conventional functionals to investigate Diels-Alder reactions quantitatively. After confirming that LC-DFT accurately reproduces the orbital energies of the reactant and product molecules of the Diels-Alder reactions, the global hardness responses, the halves of highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) energy gaps, along the intrinsic reaction coordinates of two Diels-Alder reactions were computed. We noticed that LC-DFT results satisfy the maximum hardness rule for overall reaction paths while conventional functionals violate this rule on the reaction pathways. Furthermore, our results also show that the HOMO-LUMO gap variations are close to the reaction enthalpies for these Diels-Alder reactions. Based on these results, we foresee quantitative reaction analysis on the orbital energies. Copyright © 2012 Wiley Periodicals, Inc.

An activated barrier for protection of special nuclear materials in vital areas

International Nuclear Information System (INIS)

Timm, R.E.; Miranda, J.E.

1984-01-01

The Argonne National Laboratory and Sandia National Laboratory have recently installed an activated barrier, the Access Denial System (ADS) for the upgrade of safeguards of special nuclear materials. The technology of this system was developed in the late 70's by Sandia National Laboratory-Albuquerque. The installation was the first for the Department of Energy. Subsequently, two additional installations have been completed. The Access Denial System, combined with physical restraints, provide the system delay. The principal advantages of the activated barrier are: (1) it provides an order of magnitude improvement in delay over that of a fixed barrier, (2) it can be added to existing vital areas with a minimum of renovations, (3) existing operations are minimally impacted, and (4) health and safety risks are virtually nonexistent. Hardening of the vital areas using the ADS was accomplished in a costeffective manner

Active barrier films of PET for solar cell application: Processing and characterization

International Nuclear Information System (INIS)

Rossi, Gabriella; Scarfato, Paola; Incarnato, Loredana

2014-01-01

A preliminary investigation was carried out on the possibility to improve the protective action offered by the standard multilayer structures used to encapsulate photovoltaic devices. With this aim, a commercial active barrier PET-based material, able to absorb oxygen when activated by liquid water, was used to produce flexible and transparent active barrier films, by means of a lab-scale film production plant. The obtained film, tested in terms of thermal, optical and oxygen absorption properties, shows a slow oxygen absorption kinetics, an acceptable transparency and an easy roll-to-roll processability, so proving itself as a good candidate for the development of protective coating for solar cells against the atmospheric degradation agents like the rain

Heterogeneous reactions of dioctahedral smectites in illite-smectite and kaolinite-smectite mixed-layers: applications to clay materials for engineered barriers

International Nuclear Information System (INIS)

Meunier, A.; Proust, D.; Beaufort, D.; Lajudie, A.; Petit, J.-C.

1992-01-01

The clay materials selected for use in the engineered barriers of the French nuclear waste isolation programme are mainly composed of dioctahedral smectite, either bentonite of Wyoming type or kaolinite-smectites most often consist of randomly stacked layers with low and high charges. In the case of the Wyoming-type bentonite, these two differently charged layers do not react in the same way when subjected to hydrothermal alteration. Overall, the low-charge smectite layers react to form high-charge smectite layers + quartz + kaolinite. Then, fixing K ions, the high-charge smectite layers are transformed into illite-smectite mixed-layers (I/S) when the temperature conditions increase. A symmetrical process is observed in natural or experimental hydrothermal conditions when the high-charge smectite layers of I/S minerals react with quartz and/or kaolinite to produce low-charge smectite layers. The chemical properties of the bentonite-engineered barriers clearly depend on the low charge/high charge smectite layer proportion, which is in turn controlled by the temperature-dependent reactions in the vicinity of the waste disposal. Although there are fewer published data on the kaolinite-smectite mixed-layered minerals (K/S), a similar low charge-high charge reaction appears to affect their smectite component. The experimental alteration of K/S leads to the formation of a low-charge beidellite with an increase in the cation-exchange capacity and in the expandability of the clay material. Thus, the properties of the engineered barrier seems to be improved after hydrothermal alteration. (Author)

Barriers to Physical Activity Among African American Women: An Integrative Review of the Literature.

Science.gov (United States)

Joseph, Rodney P; Ainsworth, Barbara E; Keller, Colleen; Dodgson, Joan E

2015-01-01

A key aspect for researchers to consider when developing culturally appropriate physical activity (PA) interventions for African American (AA) women are the specific barriers AA women face that limit their participation in PA. Identification and critical examination of these barriers is the first step in developing comprehensive culturally relevant approaches to promote PA and help resolve PA-related health disparities in this underserved population. We conducted a systematic integrative literature review to identify barriers to PA among AA women. Five electronic databases were searched, and forty-two studies (twenty-seven qualitative, fourteen quantitative, one mixed method) published since 1990 (range 1998-2013) in English language journals met inclusion criteria for review. Barriers were classified as intrapersonal, interpersonal, or environment/community according to their respective level of influence within our social ecological framework. Intrapersonal barriers included lack of time, knowledge, and motivation; physical appearance concerns; health concerns; monetary cost of exercise facilities; and tiredness/fatigue. Interpersonal barriers included family/caregiving responsibilities; lack of social support; and lack of a PA partner. Environmental barriers included safety concerns; lack of facilities; weather concerns; lack of sidewalks; and lack of physically active AA role models. Results provide key leverage points for researchers to consider when developing culturally relevant PA interventions for AA women.

Barriers and Facilitators to Being Physically Active on a Rural U.S. Northern Plains American Indian Reservation

Directory of Open Access Journals (Sweden)

Lisa Jahns

2014-11-01

Full Text Available The objective of the present study was to identify barriers to and facilitators of physical activity among American Indian adults living on a rural, U.S. Northern Plains reservation using the nominal group technique (NGT. NGT is a method of data generation and interpretation that combines aspects of qualitative (free generation of responses and quantitative (systematic ranking of responses methodologies. Adults participated in one of two NGT sessions asking about either barriers to (n = 6, or facilitators of (n = 5, being physically active. Participants nominated and ranked 21 barriers and 18 facilitators. Barriers indicated lack of knowledge of how to fit physical activity into a daily schedule, work, caring for family members, and prioritizing sedentary pursuits. Other responses included environmental barriers such as lack of access and transportation to a gym, unsafe walking conditions, and inclement weather. Facilitators to following recommendations included knowledge of health benefits of physical activity and the perception of physical activity as enjoyable, including feeling good when working out. Environmental facilitators included being outdoors walking and biking as well as parks and exercise facilities. Responses provided direction for locally designed community-based programs to promote facilitators and decrease barriers to individual’s engagement in physical activity.

Modeling the Electrochemical Hydrogen Oxidation and Evolution Reactions on the Basis of Density Functional Theory Calculations

DEFF Research Database (Denmark)

Skulason, Egill; Tripkovic, Vladimir; Björketun, Mårten

2010-01-01

charged Pt(111) slab and solvated protons in up to three water bilayers is considered and reaction energies and activation barriers are determined by using a newly developed computational scheme where the potential can be kept constant during a charge transfer reaction. We determine the rate limiting...... reaction on Pt(111) to be Tafel−Volmer for HOR and Volmer−Tafel for HER. Calculated rates agree well with experimental data. Both the H adsorption energy and the energy barrier for the Tafel reaction are then calculated for a range of metal electrodes, including Au, Ag, Cu, Pt, Pd, Ni, Ir, Rh, Co, Ru, Re......, W, Mo, and Nb, different facets, and step of surfaces. We compare the results for different facets of the Pt electrode to experimental data. Our results suggest that the most important parameter for describing the HOR or the HER activity of an electrode is its binding free energy of H. We present...

TRIMOLECULAR REACTIONS OF URANIUM HEXAFLUORIDE WITH WATER

Energy Technology Data Exchange (ETDEWEB)

Westbrook, M.; Becnel, J.; Garrison, S.

2010-02-25

The hydrolysis reaction of uranium hexafluoride (UF{sub 6}) is a key step in the synthesis of uranium dioxide (UO{sub 2}) powder for nuclear fuels. Mechanisms for the hydrolysis reactions are studied here with density functional theory and the Stuttgart small-core scalar relativistic pseudopotential and associated basis set for uranium. The reaction of a single UF{sub 6} molecule with a water molecule in the gas phase has been previously predicted to proceed over a relatively sizeable barrier of 78.2 kJ {center_dot} mol{sup -1}, indicating this reaction is only feasible at elevated temperatures. Given the observed formation of a second morphology for the UO{sub 2} product coupled with the observations of rapid, spontaneous hydrolysis at ambient conditions, an alternate reaction pathway must exist. In the present work, two trimolecular hydrolysis mechanisms are studied with density functional theory: (1) the reaction between two UF{sub 6} molecules and one water molecule, and (2) the reaction of two water molecules with a single UF{sub 6} molecule. The predicted reaction of two UF{sub 6} molecules with one water molecule displays an interesting 'fluorine-shuttle' mechanism, a significant energy barrier of 69.0 kJ {center_dot} mol{sup -1} to the formation of UF{sub 5}OH, and an enthalpy of reaction ({Delta}H{sub 298}) of +17.9 kJ {center_dot} mol{sup -1}. The reaction of a single UF{sub 6} molecule with two water molecules displays a 'proton-shuttle' mechanism, and is more favorable, having a slightly lower computed energy barrier of 58.9 kJ {center_dot} mol{sup -1} and an exothermic enthalpy of reaction ({Delta}H{sub 298}) of -13.9 kJ {center_dot} mol{sup -1}. The exothermic nature of the overall UF{sub 6} + 2 {center_dot} H{sub 2}O trimolecular reaction and the lowering of the barrier height with respect to the bimolecular reaction are encouraging; however, the sizable energy barrier indicates further study of the UF{sub 6} hydrolysis reaction

Gender Differences in Barriers to Physical Activity among College Students Reporting Varying Levels of Regular Physical Activity

Science.gov (United States)

Munford, Shawn N.

2011-01-01

Researchers have studied the primary determinants of physical activity in an effort to enhance health promotion initiatives nationwide. These physical activity determinants have been observed to differ among various segments of the population, suggesting a further examination of physical activity barriers among differing populations. Little…

"JCE" Classroom Activity #111: Redox Reactions in Three Representations

Science.gov (United States)

Nieves, Edgardo L. Ortiz; Barreto, Reizelie; Medina, Zuleika

2012-01-01

This activity introduces students to the concept of reduction-oxidation (redox) reactions. To help students obtain a thorough understanding of redox reactions, the concept is explored at three levels: macroscopic, submicroscopic, and symbolic. In this activity, students perform hands-on investigations of the three levels as they work at different…

Barriers to Providing Physical Education and Physical Activity in Victorian State Secondary Schools

Science.gov (United States)

Jenkinson, Kate A.; Benson, Amanda C.

2010-01-01

An on-line questionnaire was completed by 115 physical education teachers to establish the barriers to their implementation of physical education in Victorian state secondary schools. In addition, the barriers perceived by teachers to impact on students' participation in school-based physical education and physical activity were examined. The…

Aligned carbon nanotube with electro-catalytic activity for oxygen reduction reaction

Science.gov (United States)

Liu, Di-Jia; Yang, Junbing; Wang, Xiaoping

2010-08-03

A catalyst for an electro-chemical oxygen reduction reaction (ORR) of a bundle of longitudinally aligned carbon nanotubes having a catalytically active transition metal incorporated longitudinally in said nanotubes. A method of making an electro-chemical catalyst for an oxygen reduction reaction (ORR) having a bundle of longitudinally aligned carbon nanotubes with a catalytically active transition metal incorporated throughout the nanotubes, where a substrate is in a first reaction zone, and a combination selected from one or more of a hydrocarbon and an organometallic compound containing an catalytically active transition metal and a nitrogen containing compound and an inert gas and a reducing gas is introduced into the first reaction zone which is maintained at a first reaction temperature for a time sufficient to vaporize material therein. The vaporized material is then introduced to a second reaction zone maintained at a second reaction temperature for a time sufficient to grow longitudinally aligned carbon nanotubes over the substrate with a catalytically active transition metal incorporated throughout the nanotubes.

PERCEIVED BARRIERS BY UNIVERSITY STUDENTS IN THE PRACTICE OF PHYSICAL ACTIVITIES

Directory of Open Access Journals (Sweden)

Manuel Gómez-López

2010-09-01

Full Text Available The main goal of this research is to study in detail the main characteristics of university students in order to find out the reasons why they have adopted an inactive lifestyle. In order to do so, a questionnaire on the analysis of sports habits and lifestyle was given to 323 students. They were taken from a representative sample of 1834 students. These 323 students had pointed out at the moment of the fieldwork, not having practiced any sport in their spare time. Our findings point out that there are diverse reasons for this. On one hand, reasons referred to as external barriers such as lack of time, on the other hand, internal barriers such as not liking the physical activity, not seeing its practicality or usefulness, feeling lazy or with apathy, or thinking that they are not competent in this type of activities. Other reasons such as the lack of social support are grouped within the external barriers. Finally, it is important to stress that there are also differences based on gender with respect to motivation.

A coupled mechanical-chemical model for reflecting the influence of stress on oxidation reactions in thermal barrier coating

Science.gov (United States)

Chen, Lin; Yueming, Li

2018-06-01

In this paper, a coupled mechanical-chemical model is established based on the thermodynamic framework, in which the contribution of chemical expansion to free energy is introduced. The stress-dependent chemical potential equilibrium at the gas-solid interface and the stress gradient-dependent diffusion equation as well as a so-called generalized force which is conjugate to the oxidation rate are derived from the proposed model, which could reflect the influence of stresses on the oxidation reaction. Based on the proposed coupled mechanical-chemical model, a user element subroutine is developed in ABAQUS. The numerical simulation of the high temperature oxidation in the thermal barrier coating is carried out to verify the accuracy of the proposed model, and then the influence of stresses on the oxidation reaction is investigated. In thermally grown oxide, the considerable stresses would be induced by permanent volumetric swelling during the oxidation. The stresses play an important role in the chemical potential equilibrium at the gas-solid interface and strongly affect the oxidation reaction. The gradient of the stresses, however, only occurs in the extremely thin oxidation front layer, which plays a very limited role in the oxidation reaction. The generalized force could be divided into the stress-dependent and the stress-independent parts. Comparing with the stress-independent part, the stress-dependent part is smaller, which has little influence on oxidation reaction.

Identifying barriers to remaining physically active after rehabilitation: differences in perception between physical therapists and older adult patients.

Science.gov (United States)

Zalewski, Kathryn; Alt, Carlynn; Arvinen-Barrow, Monna

2014-06-01

Cross-sectional study. To describe readiness for change and barriers to physical activity in older adults and to contrast perceptions of physical therapists and patients using the Barriers to Being Active Quiz. Regular physical activity is vital to recovery after discharge from physical therapy. Physical therapists are positioned to support change in physical activity habits for those transitioning to home care. Understanding of readiness for change and barriers to physical activity could optimize recovery. Thirteen physical therapists enrolled in the study and invited patients who met the inclusion criteria to enroll (79 patients enrolled). The physical therapists provided the ICD-9 code, the physical therapist diagnosis, and completed the Barriers to Being Active Quiz as they perceived their patients would. The enrolled patients provided demographics and filled out the Satisfaction With Life Scale, the stages-of-change scale for physical activity, and the Barriers to Being Active Quiz. Patients were predominantly in the early stages of readiness for change. Both patients and physical therapists identified lack of willpower as the primary barrier to physical activity. Patients identified lack of willpower and social influence as critical barriers more often than physical therapists, whereas physical therapists identified fear of injury and lack of time more often than their patients did. Differences between physical therapists and their patients were noted for fear of injury (z = 2.66, P = .008) and lack of time (z = 3.46, P = .001). The stage of change for physical activity impacted perception of social influence (χ2 = 9.64, Pbarriers to physical activity may allow physical therapists to better tailor intervention strategies to impact physical activity behavior change.

Theoretical study on keto-enol tautomerisation of glutarimide for exploration of the isomerisation reaction pathway of glutamic acid in proteins using density functional theory

Science.gov (United States)

Fukuyoshi, Shuichi; Nakayoshi, Tomoki; Takahashi, Ohgi; Oda, Akifumi

2017-03-01

In order to elucidate the reason why glutamic acid residues have lesser racemisation reactivity than asparaginic acid, we investigated the racemisation energy barrier of piperidinedione, which is the presumed intermediate of the isomerisation reaction of L-Glu to D-Glu, by density functional theory calculations. In two-water-molecule-assisted racemisation, the activation barrier for keto-enol isomerisation was 28.1 kcal/mol. The result showed that the activation barrier for the racemisation of glutamic acid residues was not different from that for the racemisation of aspartic acid residues. Thus, glutamic acid residues can possibly cause the racemisation reaction if the cyclic intermediate stably exists.

Perceived physical activity barriers related to body weight status and sociodemographic factors among Malaysian men in Klang Valley

Science.gov (United States)

2013-01-01

Background Physical inactivity has been acknowledged as a public health issue and has received increasing attention in recent years. This cross-sectional study was conducted to determine the barriers to physical activity among Malaysian men. These barriers were analyzed with regards to sociodemographic factors, physical activity level, BMI and waist circumference. Methods Subjects in this study included 308 Malay men and 422 Chinese men aged 20 years and older. Subjects completed the International Physical Activity Questionnaire (IPAQ) and a questionnaire on barriers to physical activity, categorized into personal and psychological, physical and social environment barriers. Weight, height and waist circumference were also measured and BMI was calculated. Results Descriptive analyses showed that 79.3% of subjects were married, 52.1% had secondary educational level, 68.8% were still working, and 39.7% had household income between RM1500 to RM3500. The perception that other recreational activities with family and friends were more fun was the most frequently reported barrier, followed by weather, lack of discipline, lack of free time, lack of money, and lack of friends. Marriage status, educational level, household income, BMI, and physical activity status were shown to be associated with perceived barriers. Conclusions To increase participation in physical activity, policy makers should consider significant personal, social and environmental barriers when developing appropriate intervention programmes. Health-promoting strategies that increase awareness, knowledge, skills and motivation related to physical activity are required. PMID:23530696

Buckling of thermally fluctuating spherical shells: Parameter renormalization and thermally activated barrier crossing

Science.gov (United States)

Baumgarten, Lorenz; Kierfeld, Jan

2018-05-01

We study the influence of thermal fluctuations on the buckling behavior of thin elastic capsules with spherical rest shape. Above a critical uniform pressure, an elastic capsule becomes mechanically unstable and spontaneously buckles into a shape with an axisymmetric dimple. Thermal fluctuations affect the buckling instability by two mechanisms. On the one hand, thermal fluctuations can renormalize the capsule's elastic properties and its pressure because of anharmonic couplings between normal displacement modes of different wavelengths. This effectively lowers its critical buckling pressure [Košmrlj and Nelson, Phys. Rev. X 7, 011002 (2017), 10.1103/PhysRevX.7.011002]. On the other hand, buckled shapes are energetically favorable already at pressures below the classical buckling pressure. At these pressures, however, buckling requires to overcome an energy barrier, which only vanishes at the critical buckling pressure. In the presence of thermal fluctuations, the capsule can spontaneously overcome an energy barrier of the order of the thermal energy by thermal activation already at pressures below the critical buckling pressure. We revisit parameter renormalization by thermal fluctuations and formulate a buckling criterion based on scale-dependent renormalized parameters to obtain a temperature-dependent critical buckling pressure. Then we quantify the pressure-dependent energy barrier for buckling below the critical buckling pressure using numerical energy minimization and analytical arguments. This allows us to obtain the temperature-dependent critical pressure for buckling by thermal activation over this energy barrier. Remarkably, both parameter renormalization and thermal activation lead to the same parameter dependence of the critical buckling pressure on temperature, capsule radius and thickness, and Young's modulus. Finally, we study the combined effect of parameter renormalization and thermal activation by using renormalized parameters for the energy

Measuring Perceived Benefits and Perceived Barriers for Physical Activity

Science.gov (United States)

Brown, Seth A.

2005-01-01

Objectives: To evaluate the psychometric properties and relationship to physical activity levels of the Exercise Benefits/Barriers Scale (EBBS) among college students. Methods: A total of 398 college students completed the EBBS and a measure of self-efficacy, the Physical Exercise Self-Efficacy Scale. In addition, a subsample of 275 students also…

78 FR 4983 - Proposed Information Collection; Women Veterans Healthcare Barriers Survey Activity: Comment Request

Science.gov (United States)

2013-01-23

... Veterans Healthcare Barriers Survey Activity: Comment Request AGENCY: Veterans Health Administration... Healthcare Barriers Survey'' in any correspondence. During the comment period, comments may be viewed online... of automated collection techniques or the use of other forms of information technology. Title: Women...

Chemistry in interstellar space. [environment characteristics influencing reaction dynamics

Science.gov (United States)

Donn, B.

1973-01-01

The particular characteristics of chemistry in interstellar space are determined by the unique environmental conditions involved. Interstellar matter is present at extremely low densities. Large deviations from thermodynamic equilibrium are, therefore, to be expected. A relatively intense ultraviolet radiation is present in many regions. The temperatures are in the range from 5 to 200 K. Data concerning the inhibiting effect of small activation energies in interstellar clouds are presented in a table. A summary of measured activation energies or barrier heights for exothermic exchange reactions is also provided. Problems of molecule formation are discussed, taking into account gas phase reactions and surface catalyzed processes.

Electrode redox reactions with polarizable molecules

Science.gov (United States)

Matyushov, Dmitry V.

2018-04-01

A theory of redox reactions involving electron transfer between a metal electrode and a polarizable molecule in solution is formulated. Both the existence of molecular polarizability and its ability to change due to electron transfer distinguish this problem from classical theories of interfacial electrochemistry. When the polarizability is different between the oxidized and reduced states, the statistics of thermal fluctuations driving the reactant over the activation barrier becomes non-Gaussian. The problem of electron transfer is formulated as crossing of two non-parabolic free energy surfaces. An analytical solution for these free energy surfaces is provided and the activation barrier of electrode electron transfer is given in terms of two reorganization energies corresponding to the oxidized and reduced states of the molecule in solution. The new non-Gaussian theory is, therefore, based on two theory parameters in contrast to one-parameter Marcus formulation for electrode reactions. The theory, which is consistent with the Nernst equation, predicts asymmetry between the cathodic and anodic branches of the electrode current. They show different slopes at small electrode overpotentials and become curved at larger overpotentials. However, the curvature of the Tafel plot is reduced compared to the Marcus-Hush model and approaches the empirical Butler-Volmer form with different transfer coefficients for the anodic and cathodic currents.

Survey of the Relationship Between Activity Energy Expenditure Metabolic Equivalents and Barrier Factors of Physical Activity in the Elderly in Kashan

OpenAIRE

Sadrollahi, Ali; Khalili, Zahra; Pour Nazari, Robab; Mohammadi, Majid; Ahmadi Khatir, Maryam; Mossadegh, Najima

2016-01-01

Background Physical activity in the elderly is influenced by aspects of aging that cause personal, mental, environmental, and social changes. Increases in factors that are barriers to activity cause physical energy expenditure to decrease. Objectives The aim of the present study was to survey the relationship between energy expenditure in metabolic equivalent units (MET) and factors that are barriers to physical activity in elderly people in Kashan, Iran Methods This is a descriptive analysis...

Levels of physical activity, motivation and barriers to participation in university students.

Science.gov (United States)

Sevil, Javier; Práxedes, Alba; Abarca-Sos, Alberto; Del Villar, Fernando; García-González, Luis

2016-10-01

Grounded in self-determination theory and trans-theoretical model applied to exercise, the aim of this study was to analyse the existing relationships between physical activity (PA) carried out by university students, perceived barriers to PA, motivation to PA and stages of change. 901 Spanish students took part in the study (408 men, 493 women; mean age 22.59±3.59), who completed the Behavioural Regulation in Exercise Questionnaire (BREQ-3), Scale of Barriers to PA, Stages of Change and the International Physical Activity Questionnaire - Short Form (IPAQ-SF). Noteworthy among the findings is the positive relationship between the more autonomous regulation forms, especially integrated regulation, and the moderate to vigorous PA (MVPA) levels. However, barriers to participatrion are negatively related to PA levels and the more self-determined forms of motivation. Finally, students in action and maintenance stages, and those who comply with the recommendations on PA present higher values in the more self-determined motivation forms and lower values in barriers to participation in PA. The study shows the importance of addressing the analysis of variables associated with engagement in PA in the university population to develop healthy policies and intervention programmes that can establish a series of healthy and more active habits in the youth-adult stage. The appropriateness of promoting more self-determined motivation forms is highlighted, especially integrated regulation, to have an impact on higher levels of MVPA.

Biological and Sociocultural Differences in Perceived Barriers to Physical Activity among 5th–7th Grade Urban Girls

Science.gov (United States)

Vermeesch, Amber L.; Ling, Jiying; Voskuil, Vicki R.; Bakhoya, Marion; Wesolek, Stacey M.; Bourne, Kelly A.; Pfeiffer, Karin A.; Robbins, Lorraine B.

2015-01-01

Background Inadequate physical activity (PA) contributes to the high prevalence of overweight and obesity among U.S. adolescent girls. Barriers preventing adolescent girls from meeting PA guidelines have not been thoroughly examined. Objectives The threefold purpose of this study was to: (a) determine pubertal stage, racial/ethnic, and socioeconomic status (SES) differences in ratings of interference of barriers to PA; (b) examine relationships between perceived barriers and age, body mass index (BMI), recreational screen time, sedentary activity, and PA; and (c) identify girls’ top-rated perceived barriers to PA. Methods Girls (N = 509) from eight Midwestern U.S. schools participated. Demographic, pubertal stage, perceived barriers, and recreational screen time data were collected via surveys. Height and weight were measured. Accelerometers measured sedentary activity, moderate-to-vigorous physical activity (MVPA), and light plus MVPA. Results Girls of low SES reported greater interference of perceived barriers to PA than those who were not of low SES (1.16 vs. 0.97, p = .01). Girls in early/middle puberty had lower perceived barriers than those in late puberty (1.03 vs. 1.24, p barriers were negatively related to MVPA (r = −.10, p = .03) and light plus MVPA (r = −.11, p = .02). Girls’ top five perceived barriers included lack of skills, hating to sweat, difficulty finding programs, being tired, and having pain. Discussion Innovative interventions, particularly focusing on skill development, are needed to assist girls in overcoming their perceived barriers to PA. PMID:26325276

The breakdown of vinyl ethers as a two-center synchronous reaction

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Pokidova, T. S.; Shestakov, A. F.

2009-11-01

The experimental data on the molecular decomposition of vinyl ethers of various structures to alkanes and the corresponding aldehydes or ketones in the gas phase were analyzed using the method of intersecting parabolas. The enthalpies and kinetic parameters of decomposition were calculated for 17 reactions. The breakdown of ethers is a two-center concerted reaction characterized by a very high classical potential barrier to the thermally neutral reaction (180-190 kJ/mol). The kinetic parameters (activation energies and rate constants) of back reactions of the formation of vinyl ethers in the addition of aldehydes or ketones to alkanes were calculated using the method of intersecting parabolas. The factors that influenced the activation energy of the decomposition and formation of ethers were discussed. Quantum-chemical calculations of several vinyl ether decomposition reactions were performed. Ether formation reactions were compared with the formation of unsaturated alcohols as competitive reactions, which can occur in the interaction of carbonyl compounds with alkenes.

Exploring chemical reaction mechanisms through harmonic Fourier beads path optimization.

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Khavrutskii, Ilja V; Smith, Jason B; Wallqvist, Anders

2013-10-28

Here, we apply the harmonic Fourier beads (HFB) path optimization method to study chemical reactions involving covalent bond breaking and forming on quantum mechanical (QM) and hybrid QM∕molecular mechanical (QM∕MM) potential energy surfaces. To improve efficiency of the path optimization on such computationally demanding potentials, we combined HFB with conjugate gradient (CG) optimization. The combined CG-HFB method was used to study two biologically relevant reactions, namely, L- to D-alanine amino acid inversion and alcohol acylation by amides. The optimized paths revealed several unexpected reaction steps in the gas phase. For example, on the B3LYP∕6-31G(d,p) potential, we found that alanine inversion proceeded via previously unknown intermediates, 2-iminopropane-1,1-diol and 3-amino-3-methyloxiran-2-ol. The CG-HFB method accurately located transition states, aiding in the interpretation of complex reaction mechanisms. Thus, on the B3LYP∕6-31G(d,p) potential, the gas phase activation barriers for the inversion and acylation reactions were 50.5 and 39.9 kcal∕mol, respectively. These barriers determine the spontaneous loss of amino acid chirality and cleavage of peptide bonds in proteins. We conclude that the combined CG-HFB method further advances QM and QM∕MM studies of reaction mechanisms.

Barriers to physical activity and restorative care for residents in long-term care: a review of the literature.

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Benjamin, Kathleen; Edwards, Nancy; Ploeg, Jenny; Legault, Frances

2014-01-01

Despite the benefits of physical activity, residents living in long-term care (LTC) are relatively sedentary. Designing successful physical activity and restorative care programs requires a good understanding of implementation barriers. A database search (2002-2013) yielded seven studies (nine articles) that met our inclusion criteria. We also reviewed 31 randomized controlled trials (RCTs) to determine if the authors explicitly discussed the barriers encountered while implementing their interventions. Eleven RCTs (13 articles) included a discussion of the barriers. Hence, a total of 18 studies (22 articles) were included in this review. Barriers occurred at resident (e.g., health status), environmental (e.g., lack of space for physical activity), and organizational (e.g., staffing and funding constraints) levels. These barriers intersect to adversely affect the physical activity of older people living in LTC. Future studies targeting physical activity interventions for residents living in LTC are needed to address these multiple levels of influence.

Biological and Sociocultural Differences in Perceived Barriers to Physical Activity Among Fifth- to Seventh-Grade Urban Girls.

Science.gov (United States)

Vermeesch, Amber L; Ling, Jiying; Voskuil, Vicki R; Bakhoya, Marion; Wesolek, Stacey M; Bourne, Kelly A; Pfeiffer, Karin A; Robbins, Lorraine B

2015-01-01

Inadequate physical activity (PA) contributes to the high prevalence of overweight and obesity among U.S. adolescent girls. Barriers preventing adolescent girls from meeting PA guidelines have not been thoroughly examined. The threefold purpose of this study was to (a) determine pubertal stage, racial/ethnic, and socioeconomic status (SES) differences in ratings of interference of barriers to PA; (b) examine relationships between perceived barriers and age, body mass index, recreational screen time, sedentary activity, and PA; and (c) identify girls' top-rated perceived barriers to PA. Girls (N = 509) from eight Midwestern U.S. schools participated. Demographic, pubertal stage, perceived barriers, and recreational screen time data were collected via surveys. Height and weight were measured. Accelerometers measured sedentary activity, moderate-to-vigorous PA (MVPA), and light plus MVPA. Girls of low SES reported greater interference of perceived barriers to PA than those who were not of low SES (1.16 vs. 0.97, p = .01). Girls in early/middle puberty had lower perceived barriers than those in late puberty (1.03 vs. 1.24, p barriers were negatively related to MVPA (r = -.10, p = .03) and light plus MVPA (r = -.11, p = .02). Girls' top five perceived barriers included lack of skills, hating to sweat, difficulty finding programs, being tired, and having pain. Innovative interventions, particularly focusing on skill development, are needed to assist girls in overcoming their perceived barriers to PA.

Drug and xenobiotic biotransformation in the blood-brain barrier: A neglected issue.

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José A.G. Agúndez

2014-10-01

Full Text Available Drug biotransformation is a crucial mechanism for facilitating the elimination of chemicals from the organism and for decreasing their pharmacological activity. Published evidence suggests that brain drug metabolism may play a role in the development of adverse drug reactions and in the clinical response to drugs and xenobiotics. The blood-brain barrier (BBB has been regarded mainly as a physical barrier for drugs and xenobiotics, and little attention has been paid to BBB as a drug-metabolizing barrier. The presence of drug metabolizing enzymes in the BBB is likely to have functional implications because local metabolism may inactivate drugs or may modify the drug's ability to cross the BBB, thus modifying the drug response and the risk of developing adverse drug reactions. In this perspective paper, we discuss the expression of relevant xenobiotic metabolizing enzymes in the brain and in the BBB, and we cover current advances and future directions on the potential role of these BBB drug-metabolizing enzymes as modifiers of drug response.

Designed to deter. Community barriers to physical activity for people with visual or motor impairments.

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Kirchner, Corinne E; Gerber, Elaine G; Smith, Brooke C

2008-04-01

People with disabilities are more likely to be obese, in poor health, and get less physical activity than the general population. However, research on community factors for physical activity has generally either excluded most people with disabilities, or overlooked relevant factors of community accessibility. This exploratory study investigated environmental factors affecting people with motor impairments and people with visual impairments in urban neighborhoods. Quantitative and qualitative methods were used with a nonrandom sample (n=134) of users of four types of assistive mobility technologies: guide dogs, long canes, and motorized and manual wheelchairs. From July 2005 to August 2006, the sample participated in two telephone surveys. Between the surveys, a stratified random subsample (n =32) engaged in an ethnographic phase of observation and interviews. Most participants in all groups using assistive mobility technologies rated their neighborhoods as accessible, although they also reported many specific barriers. Users of assistive mobility technologies differed in the amount of reported physical activity and on specific barriers. Problems with sidewalk pavement and puddles/poor drainage were the most frequently mentioned environmental barriers, by 90% and 80%, respectively. Users of assistive mobility technologies were more similar on main strategies for dealing with barriers. All groups reported having to plan routes for outings, to alter planned routes, to go more slowly than planned, or to wait for a different time. Despite legislative requirements for accommodation, people with disabilities face barriers to physical activity, both in the built and social environments. Determined people with disabilities were able to overcome barriers, but required additional expenditure of resources to do so. Community design that can include people with disabilities requires detailed understanding of barriers specific both to types of impairments and to different types

Nuclear dynamics around the barrier: from fusion to evaporation

International Nuclear Information System (INIS)

Simenel, Cedric

2003-01-01

This work is devoted to aspects of nuclear dynamics around the barrier. It is shown that for fusion reactions, the Coulomb field couples relative motion of nuclei to rotation of a deformed projectile independently of the energy and the charge of the nuclei. An experimental study of the reaction 6 He + 190 Os via gamma spectroscopy of product nuclei has shown that the break up of the 6 He is coupled to the relative motion too, a strong hindrance resulting in the fusion around and above the fusion barrier. The path to fusion after overcoming the barrier, especially the charge equilibration, have been studied in the framework of the TDHF theory via the preequilibrium GDR excited in N/Z asymmetric reactions. An application to formation of the super-heavy elements has been proposed. Finally, couplings between protons and neutrons have been shown up in mean field calculations. Their main expected effect is an emission of protons under the Coulomb barrier. (author)

Application of polycrystalline diffusion barriers

International Nuclear Information System (INIS)

Tsymbal, V.A.; Kolupaev, I.N.

2010-01-01

Degradation of contacts of the electronic equipment at the raised temperatures is connected with active diffusion redistribution of components contact - metalized systems (CMS) and phase production on interphase borders. One of systems diffusion barriers (DB) are polycrystalline silicide a film, in particular silicides of the titan. Reception disilicide the titan (TiSi 2 ) which on the parameters is demanded for conditions of microelectronics from known silicides of system Ti-Si, is possible as a result of direct reaction of a film of the titan and a substrate of silicon, and at sedimentation of layer Ti-Si demanded stoichiometric structure. Simultaneously there is specific problem polycrystalline diffusion a barrier (PDB): the polycrystalline provides structural balance and metastability film disilicide, but leaves in it borders of grains - easy local ways of diffusion. In clause the analysis diffusion permeability polycrystalline and polyphase DB is made and recommendations for practical methods of increase of blocking properties PDB are made.

Barriers to Physical Activity in Low Back Pain Patients following Rehabilitation: A Secondary Analysis of a Randomized Controlled Trial

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Andrea Schaller

2017-01-01

Full Text Available Background. Promoting health-enhancing physical activity following rehabilitation is a well-known challenge. This study analysed the barriers to leisure time activity among low back pain patients. Methods. A subset of 192 low back pain patients who participated in a randomized controlled trial promoting physical activity was analysed. Physical activity, barriers, and sociodemographic and indication-related variables were assessed by a questionnaire. Differences in barriers between active and inactive participants were tested by Pearson’s chi squared test. A logistic regression model was fitted to identify influencing factors on physical activity at six months following rehabilitation. Results. Inactive and active participants differed significantly in nine of the 19 barriers assessed. The adjusted regression model showed associations of level of education (OR = 5.366 [1.563; 18.425]; p value = 0.008 and fear of pain (OR = 0.612 [0.421; 0.889]; p value = 0.010 with physical activity. The barriers included in the model failed to show any statistically significant association after adjustment for sociodemographic factors. Conclusions. Low back pain patients especially with a low level of education and fear of pain seem to need tailored support in overcoming barriers to physical activity. This study is registered at German Clinical Trials Register (DRKS00004878.

Assessment of active play, inactivity and perceived barriers in an inner city neighborhood

Science.gov (United States)

Kottyan, Gregg; Kottyan, Leah; Edwards, Nicholas M.; Unaka, Ndidi I.

2014-01-01

Avondale, a disadvantaged neighborhood in Cincinnati, lags behind on a number of indicators of child well-being. Childhood obesity has become increasingly prevalent, as one third of Avondale’s kindergarteners are obese or overweight. The study objective was to determine perceptions of the quantity of and obstacles to childhood physical activity in the Avondale community. Caregivers of children from two elementary schools were surveyed to assess their child’s physical activity and barriers to being active. Three hundred forty surveys were returned out of 1,047 for a response rate of 32%. On school days, 41% of caregivers reported that their children spent more than 2 hours watching television, playing video games, or spending time on the computer. While over half of respondents reported that their children get more than 2 hours of physical activity on school days, 14% of children were reported to be physically active less than 1 hour per day. Caregivers identified violence, cost of extracurricular activities, and lack of organized activities as barriers to their child’s physical activity. The overwhelming majority of caregivers expressed interest in a program to make local playgrounds safer. In conclusion, children in Avondale are not participating in enough physical activity and are exposed to more screen time than is recommended by the AAP. Safety concerns were identified as a critical barrier to address in future advocacy efforts in this community. This project represents an important step toward increasing the physical activity of children in Avondale and engaging the local community. PMID:24306236

Barriers to Physical Activity in Children With Autism Spectrum Disorders: Relationship to Physical Activity and Screen Time.

Science.gov (United States)

Must, Aviva; Phillips, Sarah; Curtin, Carol; Bandini, Linda G

2015-04-01

Individual, social, and community barriers to physical activity (PA) experienced by children with autism spectrum disorder (ASD) make PA participation more difficult and may contribute to increased screen time. We compared the prevalence of parent-reported barriers to PA among 58 typically developing (TD) children and 53 children with an ASD, 3 to 11 years, and assessed the association between barriers and PA participation and screen time among children with ASD. Parents of children with ASD reported significantly more barriers than parents of TD children. Based on parent-report, 60% of children with ASD required too much supervision compared with no TD children (P barriers to PA was inversely correlated with the hours spent in PA per year (r = -0.27, P = .05) and positively related to total screen time (r = .32, P < .03). These findings underscore the need for community-based PA programs designed to meet the special requirements of this population and policies that compel schools and other government-supported organizations for inclusion and/or targeted programming.

Perceived Barriers to and Facilitators of Physical Activity in Recipients of Solid Organ Transplantation, a Qualitative Study.

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Edwin J van Adrichem

Full Text Available Sufficient physical activity is important for solid organ transplant recipients (heart, lung, liver, kidney. However, recipients do not meet the recommended amount or required type of physical activity. The perceived barriers to and facilitators of physical activity in this population are largely unknown.Semi-structured in depth interviews were conducted with solid organ transplant recipients in order to explore experienced barriers and facilitators. Qualitative methodology with thematic line-by-line analysis was used for analysis, and derived themes were classified into personal and environmental factors.The most important indicated barriers were physical limitations, insufficient energy level, fear, and comorbidities. The most frequently mentioned facilitators included motivation, coping, consequences of (inactivity, routine/habit, goals/goal priority, and responsibility for the transplanted organ. Neutral factors acting as a barrier or facilitator were self-efficacy and expertise of personnel. A comparison of barriers and facilitators between transplant recipient groups yielded no overt differences.Several personal and environmental factors were indicated that should be considered in intervention development to increase physical activity behavior in solid organ transplant recipients.

Perceived barriers and facilitators to physical activity in men with prostate cancer: possible influence of androgen deprivation therapy.

Science.gov (United States)

Keogh, J W L; Patel, A; MacLeod, R D; Masters, J

2014-03-01

While physical activity is beneficial for men with prostate cancer, too few perform sufficient activity for such benefit. This study examined perceptions of men with prostate cancer of their barriers and facilitators to physical activity, and how androgen deprivation therapy (ADT) may influence these perceptions. Two focus groups were conducted, involving six ADT and eight non-ADT patients respectively. Data were transcribed verbatim and themes developed using a general inductive thematic approach. Facilitators to physical activity common to both groups of cancer survivors included clinician and spousal involvement, with pre-existing co-morbidities and increased age cited as barriers by both groups. The ADT subgroup cited personal involvement as a facilitator to physical activity, with fatigue, reduced motivation and a relative lack of specific advice from their clinician as additional barriers. The non-ADT subgroup had no additional facilitators to physical activity but cited time constraints as a barrier. These results highlight the important role that cancer clinicians and spouses play in promoting physical activity for men with prostate cancer and how ADT may influence their other facilitators and barriers. As physical activity is beneficial for prostate cancer survivors, especially those on ADT, cancer clinicians should regularly discuss physical activity with their patients. © 2013 John Wiley & Sons Ltd.

Physical activity and mental disorders: a case-control study on attitudes, preferences and perceived barriers in Italy.

Science.gov (United States)

Carpiniello, Bernardo; Primavera, Diego; Pilu, Alessandra; Vaccargiu, Nicola; Pinna, Federica

2013-12-01

Mentally ill people experience greater difficulty than the general population in exercising regularly. We aimed to evaluate attitudes displayed and barriers perceived towards physical activity in a sample of psychiatric patients. A total of 138 (M = 48, F = 90) patients attending a community mental health centre were compared with a control group made up of 138 subjects not affected by mental disorders matched for gender, mean age and education. Both groups underwent a self-administered questionnaire. Patients reported a more sedentary lifestyle in terms of weekly physical activities and daily hours of exercise; their body mass index (BMI) was significantly higher compared with the BMI of controls (p barriers to physical activity; moreover, stating how feeling sad or "distressed" reduced their propensity to physical exercise (p = 0.002). A higher number of patients (p physical activity, and the experiencing of scarce enjoyment (p barriers may limit regular physical activity in subjects affected by mental disorders; these barriers should be taken into account and appropriately addressed.

Exploring Reaction Mechanism on Generalized Force Modified Potential Energy Surfaces (G-FMPES) for Diels-Alder Reaction

Science.gov (United States)

Jha, Sanjiv; Brown, Katie; Subramanian, Gopinath

We apply a recent formulation for searching minimum energy reaction path (MERP) and saddle point to atomic systems subjected to an external force. We demonstrate the effect of a loading modality resembling hydrostatic pressure on the trans to cis conformational change of 1,3-butadiene, and the simplest Diels-Alder reaction between ethylene and 1,3-butadiene. The calculated MERP and saddle points on the generalized force modified potential energy surface (G-FMPES) are compared with the corresponding quantities on an unmodified potential energy surface. Our study is performed using electronic structure calculations at the HF/6-31G** level as implemented in the AIMS-MOLPRO code. Our calculations suggest that the added compressive pressure lowers the energy of cis butadiene. The activation energy barrier for the concerted Diels-Alder reaction is found to decrease progressively with increasing compressive pressure.

Exploring the facilitators and barriers to engagement in physical activity for people with multiple sclerosis.

Science.gov (United States)

Kayes, Nicola M; McPherson, Kathryn M; Schluter, Philip; Taylor, Denise; Leete, Marta; Kolt, Gregory S

2011-01-01

To explore the relationship that cognitive behavioural and other previously identified variables have with physical activity engagement in people with multiple sclerosis (MS). This study adopted a cross-sectional questionnaire design. Participants were 282 individuals with MS. Outcome measures included the Physical Activity Disability Survey--Revised, Cognitive and Behavioural Responses to Symptoms Questionnaire, Barriers to Health Promoting Activities for Disabled Persons Scale, Multiple Sclerosis Self-efficacy Scale, Self-Efficacy for Chronic Diseases Scales and Chalder Fatigue Questionnaire. Multivariable stepwise regression analyses found that greater self-efficacy, greater reported mental fatigue and lower number of perceived barriers to physical activity accounted for a significant proportion of variance in physical activity behaviour, over that accounted for by illness-related variables. Although fear-avoidance beliefs accounted for a significant proportion of variance in the initial analyses, its effect was explained by other factors in the final multivariable analyses. Self-efficacy, mental fatigue and perceived barriers to physical activity are potentially modifiable variables which could be incorporated into interventions designed to improve physical activity engagement. Future research should explore whether a measurement tool tailored to capture beliefs about physical activity identified by people with MS would better predict participation in physical activity.

Coupled modelling (transport-reaction) of the fluid-clay interactions and their feed back on the physical properties of the bentonite engineered clay barrier system

International Nuclear Information System (INIS)

Marty, N.

2006-11-01

The originality of this work is to process feed back effects of mineralogical and chemical modifications of clays, in storage conditions, on their physical properties and therefore on their transport characteristics (porosity, molecular diffusion, permeability). These feed back effects are modelled using the KIRMAT code (Kinetic of Reaction and MAss Transfer) developed from the kinetic code KINDIS by adding the effect of water renewal in the mineral-solution reactive cells. KIRMAT resolves mass balance equations associated with mass transport together with the geochemical reactions in a 1D approach. After 100 000 years of simulated interaction at 100 C, with the fluid of the Callovo-Oxfordian geological level (COX) and with iron provided by the steel overpack corrosion, the montmorillonite of the clay barrier is only partially transformed (into illite, chlorite, saponite...). Only outer parts of the modelled profile seem to be significantly affected by smectite dissolution processes, mainly at the interface with the geological environment. The modifications of physical properties show a closure of the porosity at the boundaries of the barrier, by creating a decrease of mass transport by molecular diffusion, essentially at the interface with the iron. Permeability laws applied to this system show a decrease of the hydraulic conductivity correlated with the porosity evolution. Near the COX, the swelling pressure of the clays from the barrier decreases. In the major part of the modelled profile, the engineered clay barrier system seems to keep its initial physical properties (porosity, molecular diffusion, permeability, swelling pressure) and functionalities. (author)

Fusion enhancement in the reactions of neutron-rich nuclei

International Nuclear Information System (INIS)

Bian Baoan; Zhang Fengshou; Zhou Hongyu

2009-01-01

The neutron-rich fusion reactions are investigated systematically using the improved isospin dependent quantum molecular dynamics model. By studying the systematic dependence of fusion barrier on neuron excess, we find the enhancement of the fusion cross sections for neutron-rich nuclear reactions that give the lowered static Coulomb barriers. The calculated fusion cross sections agree quantitatively with the experimental data. We further discuss the mechanism of the fusion enhancement of the cross sections for neutron-rich nuclear reactions by analyzing the dynamical lowering of the Coulomb barrier that is attributed to the enhancement of the N/Z ratio at the neck region.

Fusion and reactions of exotic nuclei

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Sánchez-Benítez A.M.

2011-10-01

Full Text Available Close to the drip lines, the scattering cross sections of halo nuclei show a different behaviour as compared to the tightly bound projectiles of the stability line. Several experiments carried out in the last decade have been dedicated to investigate the competition between transfer, breakup and fusion channels at energies around and below the Coulomb barrier. The rather complex scenario gives rise to conflicting conclusions concerning the effect of breakup and transfer on reaction dynamics and the sub-barrier fusion process. In this work we discuss recent experimental findings in fusion and reactions of 6He halo nucleus at energies around the Coulomb barrier.

The role of phosphate in a multistep enzymatic reaction: reactions of the substrate and intermediate in pieces.

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Kholodar, Svetlana A; Allen, C Leigh; Gulick, Andrew M; Murkin, Andrew S

2015-02-25

Several mechanistically unrelated enzymes utilize the binding energy of their substrate's nonreacting phosphoryl group to accelerate catalysis. Evidence for the involvement of the phosphodianion in transition state formation has come from reactions of the substrate in pieces, in which reaction of a truncated substrate lacking its phosphorylmethyl group is activated by inorganic phosphite. What has remained unknown until now is how the phosphodianion group influences the reaction energetics at different points along the reaction coordinate. 1-Deoxy-D-xylulose-5-phosphate (DXP) reductoisomerase (DXR), which catalyzes the isomerization of DXP to 2-C-methyl-D-erythrose 4-phosphate (MEsP) and subsequent NADPH-dependent reduction, presents a unique opportunity to address this concern. Previously, we have reported the effect of covalently linked phosphate on the energetics of DXP turnover. Through the use of chemically synthesized MEsP and its phosphate-truncated analogue, 2-C-methyl-D-glyceraldehyde, the current study revealed a loss of 6.1 kcal/mol of kinetic barrier stabilization upon truncation, of which 4.4 kcal/mol was regained in the presence of phosphite dianion. The activating effect of phosphite was accompanied by apparent tightening of its interactions within the active site at the intermediate stage of the reaction, suggesting a role of the phosphodianion in disfavoring intermediate release and in modulation of the on-enzyme isomerization equilibrium. The results of kinetic isotope effect and structural studies indicate rate limitation by physical steps when the covalent linkage is severed. These striking differences in the energetics of the natural reaction and the reactions in pieces provide a deeper insight into the contribution of enzyme-phosphodianion interactions to the reaction coordinate.

CO2 valorization by means of Dielectric Barrier Discharge

Science.gov (United States)

Machrafi, H.; Cavadias, S.; Amouroux, J.

2011-01-01

As atmospheric pollution is causing several environmental problems it is incumbent to reduce the impact of pollution on the environment. One particular problem is the production of CO2 by many transport and industrial applications. Instead of stocking CO2 and instead of being a product, it can be used as a source. The case considered is the CO2 reformation of methane producing hydrogen and CO. It is an endothermic reaction, for which the activation barrier needs to be surpassed. This can be done efficiently by the method of Dielectric Barrier Discharge. The process relies on the collision of electrons, which are accelerated under an electrical field that is created in the discharge area. This leads to the formation of reactive species, which facilitate the abovementioned reaction. This study is performed using a Matlab program with the Reaction Engineering module in COMSOL (with an incorporated kinetic mechanism) in order to model the discharge phase. Then COMSOL (continuity and Navier-Stokes equations) is used to model the flow in the post-discharge phase. The results showed that both a 2D and 3D model can be used to model the chemical-plasma process. These methods need strongly reduced kinetic mechanism, which in some cases can cause loss of precision.

CO2 valorization by means of Dielectric Barrier Discharge

International Nuclear Information System (INIS)

Machrafi, H; Cavadias, S; Amouroux, J

2011-01-01

As atmospheric pollution is causing several environmental problems it is incumbent to reduce the impact of pollution on the environment. One particular problem is the production of CO 2 by many transport and industrial applications. Instead of stocking CO 2 and instead of being a product, it can be used as a source. The case considered is the CO 2 reformation of methane producing hydrogen and CO. It is an endothermic reaction, for which the activation barrier needs to be surpassed. This can be done efficiently by the method of Dielectric Barrier Discharge. The process relies on the collision of electrons, which are accelerated under an electrical field that is created in the discharge area. This leads to the formation of reactive species, which facilitate the abovementioned reaction. This study is performed using a Matlab program with the Reaction Engineering module in COMSOL (with an incorporated kinetic mechanism) in order to model the discharge phase. Then COMSOL (continuity and Navier-Stokes equations) is used to model the flow in the post-discharge phase. The results showed that both a 2D and 3D model can be used to model the chemical-plasma process. These methods need strongly reduced kinetic mechanism, which in some cases can cause loss of precision.

Carbonylation as a key reaction in anaerobic acetone activation by Desulfococcus biacutus.

Science.gov (United States)

Gutiérrez Acosta, Olga B; Hardt, Norman; Schink, Bernhard

2013-10-01

Acetone is activated by aerobic and nitrate-reducing bacteria via an ATP-dependent carboxylation reaction to form acetoacetate as the first reaction product. In the activation of acetone by sulfate-reducing bacteria, acetoacetate has not been found to be an intermediate. Here, we present evidence of a carbonylation reaction as the initial step in the activation of acetone by the strictly anaerobic sulfate reducer Desulfococcus biacutus. In cell suspension experiments, CO was found to be a far better cosubstrate for acetone activation than CO2. The hypothetical reaction product, acetoacetaldehyde, is extremely reactive and could not be identified as a free intermediate. However, acetoacetaldehyde dinitrophenylhydrazone was detected by mass spectrometry in cell extract experiments as a reaction product of acetone, CO, and dinitrophenylhydrazine. In a similar assay, 2-amino-4-methylpyrimidine was formed as the product of a reaction between acetoacetaldehyde and guanidine. The reaction depended on ATP as a cosubstrate. Moreover, the specific activity of aldehyde dehydrogenase (coenzyme A [CoA] acylating) tested with the putative physiological substrate was found to be 153 ± 36 mU mg(-1) protein, and its activity was specifically induced in extracts of acetone-grown cells. Moreover, acetoacetyl-CoA was detected (by mass spectrometry) after the carbonylation reaction as the subsequent intermediate after acetoacetaldehyde was formed. These results together provide evidence that acetoacetaldehyde is an intermediate in the activation of acetone by sulfate-reducing bacteria.

Determination of the fission barrier height in fission of heavy radioactive beams induced by the (d,p)-transfer

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A theoretical framework is described, allowing to determine the fission barrier height using the observed cross sections of fission induced by the (d,p)-transfer with accuracy, which is not achievable in another type of low-energy fission of neutron-deficient nuclei, the $\\beta$-delayed fission. The primary goal is to directly determine the fission barrier height of proton-rich fissile nuclei, preferably using the radio-active beams of isotopes of odd elements, and thus confirm or exclude the low values of fission barrier heights, typically extracted using statistical calculations in the compound nucleus reactions at higher excitation energies. Calculated fission cross sections in transfer reactions of the radioactive beams show sufficient sensitivity to fission barrier height. In the probable case that fission rates will be high enough, mass asymmetry of fission fragments can be determined. Results will be relevant for nuclear astrophysics and for production of super-heavy nuclei. Transfer induced fission of...

Global Account of Barriers and Facilitators of Physical Activity Among Patients with Diabetes Mellitus: A Narrative Review of the Literature.

Science.gov (United States)

Adeniyi, Ade F; Anjana, Ranjit M; Weber, Mary B

2016-01-01

With diabetes rates escalating globally, there is the need for a better integration of all aspects of diabetes care for improved population outcomes. An understanding, not only of regional but global literature on physical activity barriers and its facilitators is important if healthcare providers and policy makers are to create programs tailored to their populations. Herein, we report the results of a narrative review of the global barriers and facilitators of physical activity for patients with diabetes mellitus. An in-depth literature search was conducted to identify English-language studies that examined physical activity barriers and associated facilitators among patients with diabetes mellitus. Major electronic literature databases that were searched included Google Scholar, PubMed, Hub-Med, and Highwire. Studies were available from Africa, Asia, Australia, Europe, and, predominantly North America. A total of 34 predominantly internal barriers emerged globally. The most commonly reported were time constrains, fear of provoking additional disorders, exercise venue and weather related barriers. Facilitators of physical activity were reported for most of the internal barriers (e.g. time constraints, lack of knowledge etc) while the external barriers (e.g. weather, environmental pollution etc) received only a minimal attention. Globally, patients with diabetes are confronted with an enormous number of physical activity barriers. Unlike the robust solutions proffered for the internal barriers, the literature is largely silent about solutions to the external barriers, which though fewer, may be highly influential. Additional data is needed to better understand physical activity behaviors in populations outside of North America.

Physical Activity With and Without TV Viewing: Effects on Enjoyment of Physical Activity and TV, Exercise Self-Efficacy, and Barriers to Being Active in Overweight Adults.

Science.gov (United States)

Steeves, Jeremy A; Bassett, David R; Fitzhugh, Eugene C; Raynor, Hollie; Cho, Chi; Thompson, Dixie L

2016-04-01

Physical activity (PA) is enjoyable, but there are barriers to participation. TV viewing is highly enjoyable with limited barriers. Exercising while viewing TV may impact enjoyment, exercise self-efficacy, and barriers to PA, compared with exercising without TV. 58 sedentary, overweight adults were randomized to 1 of 2 PA prescriptions: one that increased PA during TV viewing (TV Commercial Stepping), and another that focused solely on PA (Walking). Random effects models tested changes in enjoyment of TV and PA, exercise self-efficacy, and barriers to PA across time (baseline, 3, and 6 months) and PA prescription during a 6-month PA intervention. At baseline, TV was more enjoyable than PA. Over the 6-month intervention, enjoyment of TV viewing did not change, but enjoyment of PA and exercise self-efficacy significantly increased, while barriers to PA significantly decreased for both groups compared with baseline (P exercise increased, and barriers to being active were reduced for previously sedentary adults participating in a behavioral PA intervention. These findings highlight the importance of encouraging inactive adults to engage in some form of PA, whether it occurs with or without TV viewing.

Excitation functions for deuterium-induced reactions on 194Pt near the coulomb barrier

Czech Academy of Sciences Publication Activity Database

Kulko, A. A.; Skobelev, N. K.; Kroha, Václav; Penionzhkevich, Y. E.; Mrázek, Jaromír; Burjan, Václav; Hons, Zdeněk; Šimečková, Eva; Piskoř, Štěpán; Kugler, Andrej; Demekhina, N. A.; Sobolev, Yu. G.; Chuvilskaya, T. V.; Shirokova, K.; Kuterbekov, K.

2012-01-01

Roč. 9, 6-7 (2012), s. 502-507 ISSN 1547-4771 R&D Projects: GA MŠk LA08002 Institutional support: RVO:61389005 Keywords : nucelar reactions * excitation functions * charged particle activation Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders

Barriers to physical activity in chronic hemodialysis patients: a single-center pilot study in an Italian dialysis facility.

Science.gov (United States)

Fiaccadori, Enrico; Sabatino, Alice; Schito, Franco; Angella, Francesca; Malagoli, Martina; Tucci, Marco; Cupisti, Adamasco; Capitanini, Alessandro; Regolisti, Giuseppe

2014-01-01

In patients on chronic dialysis a sedentary lifestyle is a strong, yet potentially modifiable, predictor of mortality. The present single-center pilot study evaluated social, psychological and clinical barriers that may hinder physical activity in this population. We explored the association between barriers to physical activity and sedentarism in adult patients at a chronic dialysis facility in Parma, Italy. We used different questionnaries exploring participation in physical activity, physical functioning, patient attitudes and preferences, and barriers to physical activity perceived by either patients or dialysis doctors and nurses. We enrolled 104 patients, (67 males, 65%), mean age 69 years (79% of patients older than 60 years); median dialysis vintage 60 months (range 8-440); mean Charlson score 5.55, ADL (Activities of Daily Living) score 5.5. Ninety-two participants (88.5%) reported at least one barrier to physical activity. At multivariable analysis, after adjusting for age and sex, feeling to have too many medical problems (OR 2.99, 95% CI 1.27 to 7.07; P=0.012), chest pain (OR 10.78, 95% CI 1.28 to 90.28; P=0.029) and sadness (OR 2.59, 95% CI 1.10 to 6.09; P=0.030) were independently associated with physical inactivity. Lack of time for exercise counseling and the firm belief about low compliance/interest by the patients toward exercise were the most frequent barriers reported by doctors and nurses. We identified a number of patient-related and health personnel-related barriers to physical activity in patients on chronic dialysis. Solutions for these barriers should be addressed in future studies aimed at increasing the level of physical activity in this population. © 2014 S. Karger AG, Basel.

Perceived Benefits, Facilitators, Disadvantages, and Barriers for Physical Activity Amongst South Asian Adolescents in India and Canada.

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Rajaraman, Divya; Correa, Natasha; Punthakee, Zubin; Lear, Scott A; Jayachitra, Krishnaswamy G; Vaz, Mario; Swaminathan, Sumathi

2015-07-01

The purpose of this study was to understand perceived benefits, facilitators, disadvantages, and barriers for physical activity among South Asian adolescents in India and Canada. Thirteen focus group discussions with South Asian (origin) adolescent boys and girls of different nutritional status and socioeconomic status in rural and urban India and urban Canada. Across the groups, fitness and 'energy' were perceived to be major benefits of physical activity. In India, better academic performance was highlighted, while health benefits were well detailed in Canadian groups. In all settings, friends, family, and teachers were perceived as facilitators of as well as barriers to physical activity. Lack of a safe space to play was a major concern for urban adolescents, while academic pressures and preference for other sedentary recreational activities were common barriers across all groups. Girls were less likely than boys to be interested in physical activity, with girls' participation in India further limited by societal restrictions. The study suggests key areas for promotion of physical activity among South Asian adolescents: balance between academic pressure and opportunities for physical activity, especially in India; urban planning for a built environment conducive to physical activity; and gender-sensitive programming to promote girls' activity which also addresses culture-specific barriers.

Fusion barrier distributions and fission anisotropies

International Nuclear Information System (INIS)

Hinde, D.J.; Morton, C.R.; Dasgupta, M.; Leigh, J.R.; Lestone, J.P.; Lemmon, R.C.; Mein, J.C.; Newton, J.O.; Timmers, H.; Rowley, N.; Kruppa, A.T.

1995-01-01

Fusion excitation functions for 16,17 O+ 144 Sm have been measured to high precision. The extracted fusion barrier distributions show a double-peaked structure interpreted in terms of coupling to inelastic collective excitations of the target. The effect of the positive Q-value neutron stripping channel is evident in the reaction with 17 O. Fission and evaporation residue cross-sections and excitation functions have been measured for the reaction of 16 O+ 208 Pb and the fusion barrier distribution and fission anisotropies determined. It is found that the moments of the fusion l-distribution determined from the fusion and fission measurements are in good agreement. ((orig.))

A qualitative exploration of barriers and motivators to physical activity participation in women treated for breast cancer.

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Brunet, Jennifer; Taran, Samantha; Burke, Shaunna; Sabiston, Catherine M

2013-01-01

The adoption and maintenance of a physically active lifestyle among women after breast cancer is an important priority for public health and rehabilitation science. The purpose of this qualitative study was to explore breast cancer survivors' perceptions of the factors influencing their ability to maintain a self-directed physical activity program. Nine women participated in semi-structured, in-depth interviews. Data were coded into perceived barriers and motivators to maintenance of physical activity using thematic analysis. Women identified a range of physical (e.g. cancer-related physical symptoms), environmental/organizational (e.g. bad weather, lack of equipment/facilities, lack of knowledge, time constraints) and psychosocial (e.g. lack of motivation, low social support, low confidence/skill) barriers. They also identified perceived physical (e.g. weight management, health improvement or maintenance, increase energy) and psychosocial (e.g. improve body image, experience enjoyment, social support, positive emotions) motivators. These findings are consistent with research on barriers and motivators to physical activity initiation, and can be used to develop self-directed physical activity programs that target active breast cancer survivors to sustain regular engagement. Furthermore, the barriers and motivators identified represent key variables for further investigation. The present study identifies a number of perceived physical, psychosocial and organizational/environmental barriers to naturally occurring physical activity participation among active breast cancer survivors that should be addressed to ensure they maintain a physically active lifestyle This study also provides evidence that comprehensive approaches that address physical and psychosocial motivators to physical activity should be developed to assist women with a history of breast cancer maintain their physical activity levels.

PATTERNS OF PHYSICAL ACTIVITY AMONG AMERICAN INDIAN CHILDREN: AN ASSESSMENT OF BARRIERS AND SUPPORT

Science.gov (United States)

Thompson, Janice L.; Davis, Sally M.; Gittelsohn, Joel; Going, Scott; Becenti, Alberta; Metcalfe, Lauve; Stone, Elaine; Harnack, Lisa; Ring, Kim

2016-01-01

Estimates indicate that 10% to 50% of American Indian and non-Indian children in the U.S. are obese, defined as a body mass index ≥ 95th percentile of the NHANES II reference data. Pathways is a two-phase, multi-site study to develop and test a school-based obesity prevention program in American Indian schoolchildren in grades three through five. During Phase I feasibility prior to initiation of the Pathways trial, data were collected related to physical activity patterns, and the supports of, and barriers to, physical activity. Nine schools from communities representing six different tribal groups participated in this study. Multiple measures were used for data collection including direct observation, paired child interviews, and in-depth interviews and focus groups with adults. Students completed the self-administered Knowledge, Attitudes, and Behaviors (KAB) survey, and a Physical Activity Questionnaire (PAQ). Barriers to physical activity at schools included a lack of facilities, equipment, and trained staff persons for PE. Adults were not consistently active with their children, but they were highly supportive of their children’s activity level. Children reported a strong enjoyment of physical activity and strong peer support to be physically active. Weather conditions, safety concerns, and homework/chores were common barriers to physical activity reported by children and adult caregivers. The information was used to design culturally and age-appropriate, practical interventions including the five physical activity programs for schoolchildren in the Pathways study. PMID:11759094

Promoting physical activity participation among adolescents: The barriers and the suggestions

Directory of Open Access Journals (Sweden)

Niloofar Peykari

2015-01-01

Full Text Available Background: Physical activity is a complex behavior. To designing the effective intervention, qualitative researches may be allowed for greater understanding of the reasons behind the adolescences′ physical activity-related behaviors′. Methods: Using the grounded theory approach, including semi-structured focus group discussions (FGDs and in-depth interviews, we conducted a quantitative study to elicit the adolescents and key informants′ opinion regarding the satiation, needs, social and environmental barriers of adolescents′ physical activity. For FGDs, participants were selected from volunteered adolescent (aged 10-19 years of the populated western part of Tehran, which was selected as a research field. Key informants were invited from the health professionals and experts in the field of adolescents′ health. Results: According to findings, although the majority of participants agreed on the important role of physical activity, the lack of essential motivation and the pressure of educational assignments remove it from the daily program priorities. Lack of a safe environment for girls′ physical activity and high cost of professional sports were two first mentioned barriers. It was also suggested that future interventions should focus on improving more parents′ engagement and their direct participation in physical activities with their adolescents. Conclusions: We proposed the participatory strategies for adolescent′s physical activity promotion. Through which target groups participation during the designing, development, and implementation of health programs led to more effective interventions.

Study of the dynamical potential barriers in heavy ion collisions

International Nuclear Information System (INIS)

Zhu, Long; Su, Jun; Xie, Wen-Jie; Zhang, Feng-Shou

2013-01-01

The nucleus–nucleus interaction potentials for the fusion reactions 16 O + 208 Pb, 64 Ni + 64 Ni, 58 Ni + 58 Ni and 16 O + 154 Sm are extracted from the improved isospin-dependent quantum molecular dynamics model. The shell correction effects are discussed. The negative shell correction energies lower potential barriers of a certain reaction. The incident energy dependence of the potential barrier is investigated for each system. A complex phenomenon of energy dependence is observed. It is also found that incident energy dependence of the barrier radius and barrier height shows opposite behaviors. The Coulomb potential shows weak energy dependence when distance of two colliding nuclei is lower than the touching distance. The isospin effects of the potential barrier are investigated. The orientation effects of the potential barrier is also discussed for the system 16 O + 154 Sm. The fusion cross sections that correspond to the equatorial orientation of 154 Sm are very low in sub-barrier region because of the high fusion barriers and the shallow potential pockets

Motivators, barriers, and beliefs regarding physical activity in an older adult population.

Science.gov (United States)

Costello, Ellen; Kafchinski, Marcia; Vrazel, JoEllen; Sullivan, Patricia

2011-01-01

Regular physical activity (PA) plays an important role in improving and maintaining one's health, especially as one ages. Although many older Americans are aware of the benefits of regular PA, the majority do not participate in regular PA that meets recommended guidelines. The purpose of this study was to gain insight into the motivators, barriers, and beliefs regarding PA of independent-living older adults with easy access to fitness facilities. In this qualitative design, focus group interviews were used to explore the individual perceptions of physically active and inactive older adults regarding PA and exercise. Thirty-one older adults, over age 60 participated in focus group discussions regarding PA beliefs and behaviors. Groups were homogenous based on current PA behaviors. Demographic information was collected. Discussions were audiotaped and transcribed verbatim and deidentified. Two researchers independently coded for emergent themes. Interrater reliability was established (κ = 0.89). Peer review was used to further ensure trustworthiness and credibility. No significant differences were noted in age, body mass index, or educational levels between the physically active and inactive groups. Differences in perceptions were noted between the groups regarding the construct of PA, barriers to participation in regular PA, and the components of an ideal PA program. Physically inactive persons had much lower fitness expectations of a physically active older adult, more perceived barriers to regular PA, and required individual tailoring of a PA program if they were going to participate. In addition, inactive persons were intimidated by the fitness facilities and concerned about slowing others down in a group exercise setting. Both groups shared similar motivators to participate in PA, such as maintaining health and socialization; however, inactive persons also described PA as needing to be purposeful and fun. Physically inactive persons perceived themselves to be

Theoretical studies of the reactions of HCN with atomic hydrogen

International Nuclear Information System (INIS)

Bair, R.A.; Dunning, T.H. Jr.

1985-01-01

A comprehensive theoretical study has been made of the energetics of the important pathways involved in the reaction of hydrogen atoms with hydrogen cyanide. For each reaction ab initio GVB-CI calculations were carried out to determine the structures and vibrational frequencies of the reactants, transition states, and products; then POL-CI calculations were carried out to more accurately estimate the electronic contribution to the energetics of the reactions. The hydrogen abstraction reaction is calculated to be endoergic by 24 kcal/mol [expt. ΔH (0 K) = 16--19 kcal/mol] with a barrier of 31 kcal/mol in the forward direction and 6 kcal/mol in the reverse direction. For the hydrogen addition reactions, addition to the carbon atom is calculated to be exoergic by 19 kcal/mol with a barrier of 11 kcal/mol, while addition to the nitrogen center is essentially thermoneutral with a barrier of 17 kcal/mol. Calculations were also carried out on the isomerization reactions of the addition products. The cis→trans isomerization of HCNH has a barrier of only 10 kcal/mol with the trans isomer being more stable by 5 kcal/mol. The (1,2)-hydrogen migration reaction, converting H 2 CN to trans-HCNH, is endoergic by only 14 kcal/mol, but the calculated barrier for the transfer is 52 kcal/mol. The energy of the migration pathway thus lies above that of the dissociation--recombination pathway

Barriers in the implementation of a physical activity intervention in primary care settings: lessons learned.

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Josyula, Lakshmi K; Lyle, Roseann M

2013-01-01

Barriers encountered in implementing a physical activity intervention in primary health care settings, and ways to address them, are described in this paper. A randomized comparison trial was designed to examine the impact of health care providers' written prescriptions for physical activity, with or without additional physical activity resources, to adult, nonpregnant patients on preventive care or chronic disease monitoring visits. Following abysmal recruitment outcomes, the research protocol was altered to make it more appealing to all the participants, i.e., health care providers, office personnel, and patients. Various barriers--financial, motivational, and executive--to the implementation of health promotion interventions in primary health care settings were experienced and identified. These barriers have been classified by the different participants in the research process, viz., healthcare providers, administrative personnel, researchers, and patients. Some of the barriers identified were lack of time and reimbursement for health promotion activities, and inadequate practice capacity, for health care providers; increased time and labor demands for administrative personnel; constrained access to participants, and limited funding, for researchers; and superseding commitments, and inaccurate comprehension of the research protocol, for patients. Solutions suggested to overcome these barriers include financial support, e.g., funding for researchers, remuneration for health care organization personnel, reimbursement for providers, payment for participants, and free or subsidized postage, and use of health facilities; motivational strategies such as inspirational leadership, and contests within health care organizations; and partnerships, with other expert technical and creative entities, to improve the quality, efficiency, and acceptability of health promotion interventions.

Barriers to and enablers of physical activity in patients with COPD following a hospital admission: a qualitative study

Directory of Open Access Journals (Sweden)

Thorpe O

2014-01-01

Full Text Available Olivia Thorpe, Saravana Kumar, Kylie JohnstonInternational Centre for Allied Health Evidence, The Samson Institute for Health Research, School of Health Sciences, University of South Australia, Adelaide, SA, AustraliaBackground: Chronic obstructive pulmonary disease (COPD is characterized by a persistent blockage of airflow, prompting episodes of shortness of breath, commonly leading to hospitalization. Hospitalization may lead to a decline in physical activity following discharge. Physical activity has been shown to improve symptoms of COPD and reduce readmissions, and to decrease morbidity and mortality. This study aims to explore, from the perspectives of people with COPD, the barriers to and enablers of participation in physical activity following hospitalization for COPD.Methods: This study had a qualitative descriptive design and included semistructured interviews with 28 adult COPD patients who had been admitted to hospital with a primary diagnosis of exacerbation of COPD.Results: A plethora of barriers to but fewer enablers of participation in physical activity and pulmonary rehabilitation were identified for this cohort of people. The main barriers identified were health-related (comorbidities, COPD symptoms, and physical injury or illness environment-related (weather, transport, and finance, and self-related. The main enabling factors reported were access to health professionals and equipment, social support, routine and extracurricular activities, personal goals and motivation, and the effect of physical activity and "feeling better".Conclusion: This research provides a snapshot of the barriers to and enablers of physical activity and pulmonary rehabilitation in people with COPD. It is evident that there are significant barriers which hinder the ability of people with COPD to undertake and continue participation in physical activity and pulmonary rehabilitation. While there are some enablers that may counter these barriers, it is

Adolescents' Self-Efficacy to Overcome Barriers to Physical Activity Scale

Science.gov (United States)

Dwyer, John J. M.; Chulak, Tala; Maitland, Scott; Allison, Kenneth R.; Lysy, Daria C.; Faulkner, Guy E. J.; Sheeshka, Judy

2012-01-01

This paper describes a revised measure of self-efficacy to overcome barriers to moderate and vigorous physical activity in a sample of 484 high school students in Toronto, Ontario. The students had a mean age of 15.3 years. Principal axis factoring with oblique rotation yielded five factors: self-efficacy to overcome internal, harassment, physical…

Facilitators and barriers to physical activity as perceived by older adults with intellectual disability.

Science.gov (United States)

van Schijndel-Speet, Marieke; Evenhuis, Heleen M; van Wijck, Ruud; van Empelen, Pepijn; Echteld, Michael A

2014-06-01

Older people with intellectual disability (ID) are characterized by low physical activity (PA) levels. PA is important for reducing health risks and maintaining adequate fitness levels for performing activities of daily living. The aim of this study was to explore preferences of older adults with ID for specific physical activities, and to gain insight into facilitators and barriers to engaging into PA. Fourteen in-depth interviews and four focus groups were undertaken, with a total of 40 older adults with mild and moderate ID included in the analysis. NVivo software was used for analysing the transcribed verbatim interviews. In total, 30 codes for facilitators and barriers were identified. Themes concerning facilitators to PA were enjoyment, support from others, social contact and friendship, reward, familiarity, and routine of activities. Themes concerning barriers to PA were health and physiological factors, lack of self-confidence, lack of skills, lack of support, transportation problems, costs, and lack of appropriate PA options and materials. The results of the present study suggest that older adults with ID may benefit from specific PA programs, adapted to their individual needs and limitations. Results can be used for developing feasible health promotion programs for older adults with ID.

Dynamics of Db isotopes formed in reactions induced by 238U, 248Cm, and 249Bk across the Coulomb barrier

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Kaur, Gurjit; Sandhu, Kirandeep; Kaur, Amandeep; Sharma, Manoj K.

2018-05-01

The dynamical cluster decay model is employed to investigate the decay of *265Db and *267Db nuclei, formed in the 27Al+238U , 18O+249Bk , and 19F+248Cm hot fusion reactions at energies around the Coulomb barrier. First, the fission dynamics of the 27Al+238U reaction is explored by investigating the fragmentation and preformation yield of the reaction. The symmetric mass distribution of the fission fragments is observed for *265Db nucleus, when static β2 i deformations are used within hot optimum orientation approach. However, the mass split gets broaden for the use of β2 i-dynamical hot configuration of the fragments and becomes clearly asymmetric for the cold-static-deformed approach. Within the application of cold orientations of fragments, a new fission channel is observed at mass asymmetry η =0.29 . In addition to 238U-induced reaction, the work is carried out to address the fission and neutron evaporation cross sections of *267Db nucleus formed via 19F+248Cm and 18O+249Bk reactions, besides a comprehensive analysis of fusion and capture processes. Higher fusion cross sections and compound nucleus formation probabilities (PCN) are obtained for the 18O+249Bk reaction, as larger mass asymmetry in the entrance channel leads to reduced Coulomb factor. Finally, the role of sticking (IS) and nonsticking (INS) moments of inertia is analyzed for the 4 n and 5 n channels of *267Db nuclear system.

Recent developments in semiclassical mechanics: eigenvalues and reaction rate constants

International Nuclear Information System (INIS)

Miller, W.H.

1976-04-01

A semiclassical treatment of eigenvalues for a multidimensional non-separable potential function and of the rate constant for a chemical reaction with an activation barrier is presented. Both phenomena are seen to be described by essentially the same semiclassical formalism, which is based on a construction of the total Hamiltonian in terms of the complete set of ''good'' action variables (or adiabatic invariants) associated with the minimum in the potential energy surface for the eigenvalue case, or the saddle point in the potential energy surface for the case of chemical reaction

Perceptions of barriers and facilitators in physical activity participation among women in Thiruvananthapuram City, India.

Science.gov (United States)

Mathews, Elezebeth; Lakshmi, J K; Ravindran, T K Sundari; Pratt, Michael; Thankappan, K R

2016-12-01

Despite the known benefits of physical activity, very few people, especially women, are found to engage in regular physical activity. This study explored the perceptions, barriers and facilitators related to physical activity among women in Thiruvananthapuram City, India. Four focus group discussions were conducted among individuals between 25 and 60 years of age, in a few areas of Thiruvananthapuram City Corporation limits in Kerala, preparatory to the design of a physical activity intervention trial. An open-ended approach was used and emergent findings were analyzed and interpreted. Women associated physical activity mostly with household activities. The majority of the women considered their activity level adequate, although they engaged in what the researchers concluded were quite low levels of activity. Commonly reported barriers were lack of time, motivation, and interest; stray dogs; narrow roads; and not being used to the culture of walking. Facilitators of activity were seeing others walking, walking in pairs, and pleasant walking routes. Walking was reported as the most feasible physical activity by women. Physical activity promotion strategies among women should address the prevailing cultural norms in the community, and involve social norming and overcoming cultural barriers. They should also target the modifiable determinants of physical activity, such as improving self-efficacy, improving knowledge on the adequacy of physical activity and its recommendations, facilitating goal-setting, and enhancing social support through peer support and group-based activities. © The Author(s) 2015.

CO oxidation on PtSn nanoparticle catalysts occurs at the interface of Pt and Sn oxide domains formed under reaction conditions

KAUST Repository

Michalak, William D.

2014-04-01

The barrier to CO oxidation on Pt catalysts is the strongly bound adsorbed CO, which inhibits O2 adsorption and hinders CO2 formation. Using reaction studies and in situ X-ray spectroscopy with colloidally prepared, monodisperse ∼2 nm Pt and PtSn nanoparticle catalysts, we show that the addition of Sn to Pt provides distinctly different reaction sites and a more efficient reaction mechanism for CO oxidation compared to pure Pt catalysts. To probe the influence of Sn, we intentionally poisoned the Pt component of the nanoparticle catalysts using a CO-rich atmosphere. With a reaction environment comprised of 100 Torr CO and 40 Torr O2 and a temperature range between 200 and 300 C, Pt and PtSn catalysts exhibited activation barriers for CO2 formation of 133 kJ/mol and 35 kJ/mol, respectively. While pure Sn is readily oxidized and is not active for CO oxidation, the addition of Sn to Pt provides an active site for O2 adsorption that is important when Pt is covered with CO. Sn oxide was identified as the active Sn species under reaction conditions by in situ ambient pressure X-ray photoelectron spectroscopy measurements. While chemical signatures of Pt and Sn indicated intermixed metallic components under reducing conditions, Pt and Sn were found to reversibly separate into isolated domains of Pt and oxidic Sn on the nanoparticle surface under reaction conditions of 100 mTorr CO and 40 mTorr O2 between temperatures of 200-275 C. Under these conditions, PtSn catalysts exhibited apparent reaction orders in O2 for CO 2 production that were 0.5 and lower with increasing partial pressures. These reaction orders contrast the first-order dependence in O 2 known for pure Pt. The differences in activation barriers, non-first-order dependence in O2, and the presence of a partially oxidized Sn indicate that the enhanced activity is due to a reaction mechanism that occurs at a Pt/Sn oxide interface present at the nanoparticle surface. © 2014 Published by Elsevier Inc.

Identifying Facilitators and Barriers to Physical Activity for Adults with Down Syndrome

Science.gov (United States)

Mahy, J.; Shields, N.; Taylor, N. F.; Dodd, K. J.

2010-01-01

Background: Adults with Down syndrome are typically sedentary, and many do not participate in the recommended levels of physical activity per week. The aim of this study was to identify the facilitators and barriers to physical activity for this group. Method: Semi-structured interviews were conducted to elicit the views of adults with Down…

Fuzzy barrier distributions

International Nuclear Information System (INIS)

Piasecki, E.

2009-01-01

Heavy-ion collisions often produce a fusion barrier distribution with structures displaying a fingerprint of couplings to highly collective excitations [1]. Basically the same distribution can be obtained from large-angle quasi-elastic scattering, though here the role of the many weak direct-reaction channels is unclear. For 2 0N e + 9 0Z r we have observed the barrier structures expected for the highly deformed neon projectile, but for 2 0N e + 9 2Z r we find completely smooth distribution (see Fig.1). We find that transfer channels in these systems are of similar strength but single particle excitations are significantly stronger in the latter case. They apparently reduce the 'resolving power' of the quasi-elastic channel, what leads to smeared out, or 'fuzzy' barrier distribution. This is the first case when such a phenomenon has been observed.(author)

Barriers and Motivators to Physical Activity among African American Women

Science.gov (United States)

James, Delores C. S.; Efunbumi, Orisatalabi; Harville, Cedric; Sears, Cynthia

2014-01-01

The goals of the study were to identify the barriers and motivators for physical activity (PA) and to assess whether these factors vary by weight status. A self-administered survey was completed by 413 African American women. Each woman provided verbal informed consent and was weighed and measured by a research team member. The participants' mean…

Perceived Barriers, Facilitators and Benefits for Regular Physical Activity and Exercise in Patients with Rheumatoid Arthritis: A Review of the Literature.

Science.gov (United States)

Veldhuijzen van Zanten, Jet J C S; Rouse, Peter C; Hale, Elizabeth D; Ntoumanis, Nikos; Metsios, George S; Duda, Joan L; Kitas, George D

2015-10-01

Rheumatoid arthritis (RA) is an autoimmune disease, which not only affects the joints but can also impact on general well-being and risk for cardiovascular disease. Regular physical activity and exercise in patients with RA have numerous health benefits. Nevertheless, the majority of patients with RA are physically inactive. This indicates that people with RA might experience additional or more severe barriers to physical activity or exercise than the general population. This narrative review provides an overview of perceived barriers, benefits and facilitators of physical activity and exercise in RA. Databases were searched for articles published until September 2014 using the terms 'rheumatoid arthritis', 'physical activity', 'exercise', 'barriers', 'facilitators', 'benefits', 'motivation', 'motivators' and 'enablers'. Similarities were found between disease-specific barriers and benefits of physical activity and exercise, e.g. pain and fatigue are frequently mentioned as barriers, but reductions in pain and fatigue are perceived benefits of physical activity and exercise. Even though exercise does not influence the existence of barriers, physically active patients appear to be more capable of overcoming them. Therefore, exercise programmes should enhance self-efficacy for exercise in order to achieve long-term physical activity and exercise behaviour. Encouragement from health professionals and friends/family are facilitators for physical activity and exercise. There is a need for interventions that support RA patients in overcoming barriers to physical activity and exercise and help sustain this important health behaviour.

Role amplification of the coulomb interaction in nuclear reactions

Energy Technology Data Exchange (ETDEWEB)

Kumar, Ashok; Soni, S K; Pancholi, S K; Gupta, S L [AN SSSR, Moscow. Radiotekhnicheskij Inst.

1976-10-01

The genarally adopted estimate of coulomb interaction in nuclear reactions based on the comparison of relative energies of real particles participating in the reaction with the coulomb barrier has been shown to provide wrong presentation of the role of coulomb interaction in the reaction mechanism. The relative energy of particles participating in virtual processes forming the reaction mechanism and its relation to the coulomb barrier turn out to be tens of per cent less than for the particles in an inlet channel. This is the main reason of increasing the role of coulomb interaction in the reaction mechanism. This increase is particularly significant for nuclei with large charges, in particular, in heavy ion reaction.

Physical Activity Correlates in Middle School Adolescents: Perceived Benefits and Barriers and Their Determinants.

Science.gov (United States)

Roth, Sarah E; Gill, Monique; Chan-Golston, Alec M; Rice, Lindsay N; Crespi, Catherine M; Koniak-Griffin, Deborah; Cole, Brian L; Upchurch, Dawn M; Prelip, Michael L

2018-01-01

The purpose of this study was to examine the determinants of benefits and barriers and their relationship with physical activity (PA) among predominantly Latino middle school students. Data were collected in a cross-sectional survey of 4,773 seventh-grade students recruited from a large, urban school district in Los Angeles. Hierarchical logistic regression models were used to assess determinants of benefits and barriers as well as their association with self-reported PA. Differences in benefits and barriers were observed by gender, ethnicity, and body size. Barriers were negatively correlated with all three PA outcomes while benefits were positively associated with exercising at least 60 min daily. A deeper understanding of benefits and barriers can facilitate the development of interventions and collaborative efforts among physical education teachers, school nurses, and administrators to implement comprehensive approaches that encourage students' participation in PA inside and outside of the classroom.

Chemical interaction of tetravalent actinides simulators and the engineering barrier

International Nuclear Information System (INIS)

Chain, Pablo; Alba, Maria D.; Castro, Miguel A.; Pavon, Esperanza; Mar Orta, M.

2010-01-01

Document available in extended abstract form only. The Deep Geological Repository (DGR) is the most internationally accepted option for the storage of high radioactive wastes. This confinement is based on the Multi-barrier Concept where the engineered barrier is a crucial safety wise. Nowadays, bentonite is accepted as the best argillaceous material in the engineered barrier of DGR. Additionally to its well-known physical role, a chemical interaction between lutetium, as actinide simulator, and the smectite has been demonstrated. The existence of a reaction mechanism, which was not previously described, based on the chemical interaction between the lanthanide cations and the orthosilicate anions of the lamellar structure has been identified. This finding has aroused the interest of the scientific community because lanthanides are used as simulators of high activity radionuclide (HAR) in agreement with the guidelines established in the bibliography. It has been observed that in conditions of moderate temperature and pressure a chemical interaction exists between smectites and rare earth elements (RE) and phases of insoluble di-silicate, RE 2 Si 2 O 7 , which would immobilize RE, are generated. It is remarkable that the reaction extends to all the set of the smectites, although they do not display the same reactivity, the saponite being the most reactive. The main isotopes present in the HLW belong to the actinide elements Np, Pu, Am and Cm, in addition to uranium generated by neutron capture during the fuel combustion process. The study of the mobilization of actinide (IV) thorough the bentonite barrier is limited because of their radioactivity. However, U(IV), Np(IV), Pu(IV) and Th(IV) can be simulated by the stable isotopes of the Zr(IV) and Hf(IV), because they exhibit ionic radius and physicochemical properties very similar to those of the actinide elements. It is the main objective of this research to investigate the chemical interaction of Zr(IV) as actinide

Homogeneous conversion of methane to methanol. 2. Catalytic activation of methane by cis- and trans-platin: A density functional study of the Shilov type reaction

Energy Technology Data Exchange (ETDEWEB)

Mylvaganam, K.; Bacskay, G.B.; Hush, N.S.

2000-03-08

The C-H activation of methane catalyzed by cis- and trans-platin in aqueous solution has been studied by density functional based computational methods. By analogy with the Shilov reaction, the initial step is the replacement of an ammonia ligand by methane, followed by the formation of a methyl complex and the elimination o a proton. The computations utilize the B3LYP hybrid functionals, effective core potentials, and double-{zeta} to polarized double-{zeta} basis sets and include solvation effects by a dielectric continuum method. In contrast with the Shilov reaction studied by Seigbahn and Crabtree (J.Am.Chem.Soc. 1996, 118, 4443), in the platins the replacement of an ammonia ligand by methane is found to be effectively rate determining, in that the energy barriers to C-H activation are comparable with those of the initial substitution reaction, viz. {approximately} 34 and 44 kcal/mol for cis- and trans-platin, respectively. Several reaction pathways for C-H activation and subsequent proton elimination were identified. For cis-platin the energy barriers associated with the oxidative addition and {sigma}-bond metathesis type mechanisms were found to be comparable, while for trans-platin oxidative addition is predicted to be strongly preferred over {sigma}-bond metathesis, which, interestingly, also proceeds through a Pt(IV) methyl hydrido complex as reaction intermediate. In line with accepted ideas on trans influence, the methyl and hydride ligands in the Pt(IV) complexes that arise in the oxidative addition reactions were always found to be cis to each other. On the basis of the population analyses on the Pt(IV) complexes it is suggested that the Pt-H and Pt-CH{sub 3} bonds are best described as covalent bonds and, further, that the preference of the hydride and methyl anions to be cis to each other is a consequence of such covalent bonding. In light of these findings, the energies of several methyl Pt(IV) hydrido bisulfate complexes were also recalculated

Improved Reaction and Activation Energies of [4+2] Cycloadditions, [3+3] Sigmatropic Rearrangements and Electrocyclizations with the Spin-Component-Scaled MP2 Method

NARCIS (Netherlands)

Goumans, T.P.M.; Ehlers, A.W.; Lammertsma, K.; Wuerthwein, E.-U.; Grimme, S.

2004-01-01

A new quantum mechanical scheme to calculate electronic correlation energies, spin-component-scaled MP2, was tested as a tool to predict reaction energies and barriers in computational organic chemistry. Three common pericyclic reactions with known unsatisfactory MP2 descriptions were reinvestigated

Motivators of and Barriers to Engaging in Physical Activity: Perspectives of Low-Income Culturally Diverse Adolescents and Adults.

Science.gov (United States)

Bragg, Marie A; Tucker, Carolyn M; Kaye, Lily B; Desmond, Frederic

2009-01-01

Obesity rates are rising in the United States, especially among low-income and racial/ethnic minority individuals. Exploring motivators and barriers relative to engaging in physical activity is imperative. The purpose of this study was to identify motivators and barriers relative to engagement in physical activity as reported by culturally diverse low-income adolescents and adults. A total of 91 adolescent (11 to 15 years of age) and adult (18 years of age or older) participants who self-identified as African American, Hispanic, or non-Hispanic White engaged in age group-, race/ethnicity-, and gender-concordant focus groups. Qualitative data analysis indicated that the motivators and barriers most commonly identified among the adolescent and adult focus groups were: social influence; time and priorities; physical environment; fun and enjoyment; inherently physical activities; weight concerns; fatigue, physical discomfort and current fitness level; and immediate positive feelings. Findings were generally similar across age group, gender and race/ethnicity. Age group-specific, gender-specific and race/ethnicity-specific motivators and barriers were related to how commonly the motivators and barriers were identified among each group. Implications for increasing physical activity among low-income culturally diverse adolescents and adults are discussed.

Perceived barriers and enablers of physical activity in postpartum women: a qualitative approach

OpenAIRE

Saligheh, Maryam; McNamara, Beverley; Rooney, Rosanna

2016-01-01

Background Postpartum women?s recovery from birth can be assisted through increased physical activity (PA). However, women face substantial barriers to participating in exercise and require support to enable them to benefit from increased PA. Methods This study sought to explore women?s beliefs about and experiences of PA and exercise during the 6?weeks to 12?months postpartum period. A cohort of 14 postpartum women from a survey study of the barriers and enablers to exercise participation ag...

Liquid-drop effects in sub-barrier fusion reactions

Energy Technology Data Exchange (ETDEWEB)

Aguiar, C E; Barbosa, V C; Canto, L F; Donangelo, R

1988-01-28

We introduce an operational measure for the enhancement of the fusion cross section at sub-barrier energies in terms of an asymptotic energy shift ..delta..E. It is shown that ..delta..E has a continuously growing trend with the size of the system. This trend is explained in terms of neck formation using the liquid-drop model. Deviations from this trend are attributed to strong coupling to specific channels.

Women bound to be active (years 3 and 4): can a book club help women overcome barriers to physical activity and improve self-worth?

Science.gov (United States)

Huberty, Jennifer L; Vener, Jamie; Ransdell, Lynda; Schulte, Laura; Budd, Melissa A; Gao, Yong

2010-01-01

Little progress has been made toward increasing physical activity in women. This study aimed to determine if an 8-month theory-based book club intervention (Women Bound to Be Active) was effective in increasing: (a) self-worth, (b) benefits relative to barriers to physical activity, and (c) physical activity in women (n = 51). Findings suggested a book club was effective for improving: self-worth, the benefits relative to barriers to physical activity, and possibly participation in physical activity. This is an innovative model to help women become more active and learn skills that may enable them to be active on their own long after a physical activity program has ended.

On the pH dependence of electrochemical proton transfer barriers

DEFF Research Database (Denmark)

Rossmeisl, Jan; Chan, Karen; Skulason, Egill

2016-01-01

The pH dependence of rate of the hydrogen evolution/oxidation reaction HER/HOR is investigated. Based on thermodynamic considerations, a possible explanation to the low exchange current for hydrogen reactions in alkaline is put forward. We propose this effect to be a consequence of the change...... environment in the double layer region. The entropic barrier can be rate determining only when the surface catalysis is fast. Therefore the effect of pH is most pronounced on good catalysts and for fast reactions. This entropic barrier is also in a good agreement with the unusually low prefactor measured...

The Effect of Sports and Physical Activity on Elderly Reaction Time and Response Time

Directory of Open Access Journals (Sweden)

Abdolrahman Khezri

2014-07-01

Full Text Available Objectives: Physical activities ameliorate elderly motor and cognitive performance. The aim of this research is to study the effect of sport and physical activity on elderly reaction time and response time. Methods & Materials: The research method is causal-comparative and its statistical population consists of 60 active and non-active old males over 60 years residing at Mahabad city. Reaction time was measured by reaction timer apparatus, made in Takei Company (YB1000 model. Response time was measured via Nelson’s Choice- Response Movement Test. At first, reaction time and then response time was measured. For data analysis, descriptive statistic, K-S Test and One Sample T Test were used Results K-S Test show that research data was parametric. According to the results of this research, physical activity affected reaction time and response time. Results: of T test show that reaction time (P=0.000 and response time (P=0.000 of active group was statistically shorter than non- active group. Conclusion: The result of current study demonstrate that sport and physical activity, decrease reaction and response time via psychomotor and physiological positive changes.

Assessment of physical inactivity and perceived barriers to physical activity among health college students, south-western Saudi Arabia.

Science.gov (United States)

Awadalla, N J; Aboelyazed, A E; Hassanein, M A; Khalil, S N; Aftab, R; Gaballa, I I; Mahfouz, A A

2014-10-20

Physical inactivity is a public health problem in Saudi Arabia. A cross-sectional study was carried out to evaluate the pattern of physical activity, predictors of physical inactivity and perceived barriers to physical activity among health college students in King Khalid University. A total of 1257 students (426 males and 831 females) were recruited. The Arabic short form of the International Physical Activity Questionnaire was used. Overall, 58.0% of the students were physically inactive. Only 13.4% of the students performed vigorous physical activity, 14.8% moderate-intensity physical activity and 29.9% walking activities which met World Health Organization criteria of health-enhancing physical activities. The prevalence of inactive leisure time was 47.5%. The independent predictors of physical inactivity were non-membership of sports clubs and being a medical student. The top reported barrier to physical activity among inactive students was time limitations (51.3%). Overcoming perceived barriers may increase physical activity among students.

[Construction and validation of a short scale of perception of barriers for the physical activity in adolescents].

Science.gov (United States)

Cabanas-Sánchez, Verónica; Tejero-González, Carlos M; Veiga, Oscar L

2012-01-01

One of the main problems of health in the first world is the increase of physical inactivity. In this respect, adolescence has been identified as a critic period with high decline of physical activity. Therefore, a relevant line of research is the understanding of this social phenomenon. The aim of this study was to design a scale to assess perceived barriers to physical activity on adolescents. A convenience sample of 160 Spanish adolescents (84 girls), between 12 and 18 years old, was recruited for this study. Firstly, there were designed 40 items whose pertinence was evaluated through content validation by experts. Later, the participants were divided in two randomized groups, and Exploratory Factor Analysis and Confirmatory Factor Analysis were performed to define a short scale of 12 items. Cronbach Alfa Coefficent was used to evaluate internal consistence of the instrument. The scale reports four dimensions: incompatibility barriers (2 items), self-concept barriers (4 items), amotivation barriers (4 items) and social barriers (2 items). The scale showed enough construct validity (χ2=60.78; d.f.=48; p=0.100; GFI=0.88; CFI=0.94; RMSEA=0.58) and high internal reliability (α=0.80). Moreover, the scale was able to explain 67% of the data variance. The Short Scale of Perceived Barriers to Physical Activity in Adolescents is a valid and reliable instrument.

Removal of atrazine in water by combination of activated carbon and dielectric barrier discharge

Energy Technology Data Exchange (ETDEWEB)

Vanraes, Patrick, E-mail: patrick.vanraes@ugent.be [Department of Applied Physics, Ghent University, Sint-Pietersnieuwstraat 41 B4, 9000 Gent (Belgium); Willems, Gert; Nikiforov, Anton [Department of Applied Physics, Ghent University, Sint-Pietersnieuwstraat 41 B4, 9000 Gent (Belgium); Surmont, Pieter; Lynen, Frederic [Separation Science Group, Department of Organic Chemistry, Ghent University, Krijgslaan 281 S4-bis, 9000 Gent (Belgium); Vandamme, Jeroen; Van Durme, Jim [Research Group Molecular Odor Chemistry, Department of Microbial and Molecular Systems (M2S), KU Leuven, Technology Campus, Gebroeders De Smetstraat 1, 9000 Gent (Belgium); Verheust, Yannick P.; Van Hulle, Stijn W.H.; Dumoulin, Ann [Department of Industrial Biological Sciences, Ghent University, Graaf Karel de Goedelaan 5, 8500 Kortrijk (Belgium); Leys, Christophe [Department of Applied Physics, Ghent University, Sint-Pietersnieuwstraat 41 B4, 9000 Gent (Belgium)

2015-12-15

Highlights: • Increasing input power with a factor 3.5 leads to deeper atrazine oxidation without significantly changing energy yield of atrazine removal. • Chlorine containing oxidation by-products of first and later generations are detected with HPLC–MS analysis, in agreement with literature. • Desorption analysis shows lower atrazine concentration and higher by-product concentration on activated carbon textile after plasma treatment. • Comparison with plasma reactors described in literature for atrazine decomposition confirms relatively high energy efficiency of our reactor. - Abstract: Efficiency of modern wastewater treatment plants to remove or decompose persistent contaminants in low concentration is often insufficient to meet the demands imposed by governmental laws. Novel, efficient and cheap methods are required to address this global issue. We developed a new type of plasma reactor, in which atrazine decomposition by atmospheric dielectric barrier discharge (DBD) in dry air is combined with micropollutant adsorption on activated carbon textile and with extra bubbling of generated ozone. Investigation of reaction kinetics and by-product analysis shows that increasing input power with a factor 3.5 leads to deeper atrazine oxidation without significantly changing energy yield of atrazine removal. By-products of first and later generations are detected with HPLC–MS analysis in water and adsorbed on the activated carbon textile. Our reactor is compared in energy efficiency with reactors described in literature, showing that combination of plasma discharge with pollutant adsorption and ozone recycling is attractive for future applications of water treatment.

Removal of atrazine in water by combination of activated carbon and dielectric barrier discharge

International Nuclear Information System (INIS)

Vanraes, Patrick; Willems, Gert; Nikiforov, Anton; Surmont, Pieter; Lynen, Frederic; Vandamme, Jeroen; Van Durme, Jim; Verheust, Yannick P.; Van Hulle, Stijn W.H.; Dumoulin, Ann; Leys, Christophe

2015-01-01

Highlights: • Increasing input power with a factor 3.5 leads to deeper atrazine oxidation without significantly changing energy yield of atrazine removal. • Chlorine containing oxidation by-products of first and later generations are detected with HPLC–MS analysis, in agreement with literature. • Desorption analysis shows lower atrazine concentration and higher by-product concentration on activated carbon textile after plasma treatment. • Comparison with plasma reactors described in literature for atrazine decomposition confirms relatively high energy efficiency of our reactor. - Abstract: Efficiency of modern wastewater treatment plants to remove or decompose persistent contaminants in low concentration is often insufficient to meet the demands imposed by governmental laws. Novel, efficient and cheap methods are required to address this global issue. We developed a new type of plasma reactor, in which atrazine decomposition by atmospheric dielectric barrier discharge (DBD) in dry air is combined with micropollutant adsorption on activated carbon textile and with extra bubbling of generated ozone. Investigation of reaction kinetics and by-product analysis shows that increasing input power with a factor 3.5 leads to deeper atrazine oxidation without significantly changing energy yield of atrazine removal. By-products of first and later generations are detected with HPLC–MS analysis in water and adsorbed on the activated carbon textile. Our reactor is compared in energy efficiency with reactors described in literature, showing that combination of plasma discharge with pollutant adsorption and ozone recycling is attractive for future applications of water treatment.

Improvement of ACE inhibitory activity of casein hydrolysate by Maillard reaction with xylose.

Science.gov (United States)

Hong, Xu; Meng, Jun; Lu, Rong-Rong

2015-01-01

The Maillard reaction is widely used to improve the functional properties or biological activities of food. The purpose of this study was to investigate the effect of the Maillard reaction on angiotensin I converting enzyme (ACE) inhibitory activity in a casein hydrolysate-xylose system. Two-step hydrolysis was used to prepare casein ACE inhibitory peptides. Maillard reaction products (MRPs) were prepared by heating hydrolyzed casein with xylose at pH 8.0, 110 °C for up to 16 h. The results showed that the content of free amino group decreased (P Maillard reaction (P reaction in the MRPs. The study shows that the Maillard reaction under appropriate conditions can improve the ACE inhibitory activity of casein hydrolysate effectively. © 2014 Society of Chemical Industry.

A prospective examination of exercise and barrier self-efficacy to engage in leisure-time physical activity during pregnancy.

Science.gov (United States)

Cramp, Anita G; Bray, Steven R

2009-06-01

Pregnant women without medical contraindications should accumulate 30 min of moderate exercise on most days of the week, yet many pregnant women do not exercise at recommended levels. The purpose the study was to examine barriers to leisure-time physical activity (LTPA) and investigate barrier and exercise self-efficacy as predictors of self-reported LTPA during pregnancy. Pregnant women (n = 160) completed questionnaires eliciting barriers to LTPA, measures of exercise and barrier self-efficacy, and 6-week LTPA recall at gestational weeks 18, 24, 30, and 36. A total of 1,168 barriers were content-analyzed, yielding nine major themes including fatigue, time constraints, and physical limitations. Exercise self-efficacy predicted LTPA from gestational weeks 18 to 24 (beta = 0.32, R(2) = 0.26) and weeks 30 to 36 (beta = 0.41, R(2) = 0.37), while barrier self-efficacy predicted LTPA from weeks 24 to 30 (beta = 0.40, R(2) = 0.32). Pregnant women face numerous barriers to LTPA during pregnancy, the nature of which may change substantially over the course of pregnancy. Higher levels of self-efficacy to exercise and to overcome exercise barriers are associated with greater LTPA during pregnancy. Research and interventions to understand and promote LTPA during pregnancy should explore the dynamic nature of exercise barriers and foster women's confidence to overcome physical activity barriers.

Thermal activation of current in an inhomogeneous Schottky diode with a Gaussian distribution of barrier height

International Nuclear Information System (INIS)

Guo-Ping, Ru; Rong, Yu; Yu-Long, Jiang; Gang, Ruan

2010-01-01

This paper investigates the thermal activation behaviour of current in an inhomogeneous Schottky diode with a Gaussian distribution of barrier height by numerical simulation. The analytical Gaussian distribution model predicted that the I-V-T curves may intersect with the possibility of the negative thermal activation of current, but may be contradictory to the thermionic emission mechanism in a Schottky diode. It shows that the cause of the unphysical phenomenon is related to the incorrect calculation of current across very low barriers. It proposes that junction voltage V j , excluding the voltage drop across series resistance from the external bias, is a crucial parameter for correct calculation of the current across very low barriers. For correctly employing the thermionic emission model, V j needs to be smaller than the barrier height ø. With proper scheme of series resistance connection where the condition of V j > ø is guaranteed, I-V-T curves of an inhomogeneous Schottky diode with a Gaussian distribution of barrier height have been simulated, which demonstrate normal thermal activation. Although the calculated results exclude the intersecting possibility of I-V-T curves with an assumption of temperature-independent series resistance, it shows that the intersecting is possible when the series resistance has a positive temperature coefficient. Finally, the comparison of our numerical and analytical results indicates that the analytical Gaussian distribution model is valid and accurate in analysing I-V-T curves only for small barrier height inhomogeneity. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

Motivators of and Barriers to Engaging in Physical Activity: Perspectives of Low-Income Culturally Diverse Adolescents and Adults

Science.gov (United States)

Bragg, Marie A.; Tucker, Carolyn M.; Kaye, Lily B.; Desmond, Frederic

2009-01-01

Background: Obesity rates are rising in the United States, especially among low-income and racial/ethnic minority individuals. Exploring motivators and barriers relative to engaging in physical activity is imperative. Purpose: The purpose of this study was to identify motivators and barriers relative to engagement in physical activity as reported…

Aspartate aminotransferase: the kinetic barriers facing the covalent intermediates on the reaction pathway

International Nuclear Information System (INIS)

Kirsch, J.F.; Julin, D.A.; McLeish, M.; Wiesinger, H.

1986-01-01

The intermediates, aldimine (A), quinonoid (Q) and ketimine (K), along the transaminase reaction coordinate were probed by isotope transfer and solvent exchange kinetics. Less than 0.003% of 3 H is transferred from C/sub α/[ 3 H]-aspartate to pyridoxamine phosphate in the cytoplasmic aspartate aminotransferase (cAATase) reaction implying either that Q does not exist as a kinetically competent intermediate or that there is a rapid exchange of isotope with solvent. The ratio of the rate constants for C/sub α/ hydrogen exchange vs keto acid product formation (k/sub exge//k/sub prod/) are 2.5 and 0.5 for the reactions of cAATase with C/sub α/ [ 2 H]-aspartate and mitochondrial (m) AATase with C/sub α/[ 2 H]-glutamate respectively. The latter reaction was also probed from the α-keto-glutarate side with carbonyl 0-18 enriched keto acid. This experiment gave k/sub exge//k/sub prod/ = 1.0 for oxygen-18 exchange in α-ketoglutarate versus amino acid formation. The two exchange experiments with mAATase are interpreted in terms of a model in which the rate constant for diffusion of water from the active site is comparable with those for product forming steps

Development of various reaction abilities and their relationships with favorite play activities in preschool children.

Science.gov (United States)

Miyaguchi, Kazuyoshi; Demura, Shinich; Sugiura, Hiroki; Uchiyama, Masanobu; Noda, Masahiro

2013-10-01

This study examines the development of various reaction movements in preschool children and the relationship between reaction times and favorite play activities. The subjects were 167 healthy preschool children aged 4-6 (96 boys and 71 girls). This study focused on the reaction times of the upper limbs (reaction 1: release; reaction 2: press) and the whole body (reaction 3: forward jump). The activities frequently played in preschools are largely divided into dynamic play activities (tag, soccer, gymnastics set, dodge ball, and jump rope) and static play activities (drawing, playing house, reading, playing with sand, and building blocks). The subjects chose 3 of 10 cards picturing their favorite play activities, depicting 10 different activities. All intraclass correlation coefficients of measured reaction times were high (0.73-0.79). In addition, each reaction time shortened with age. Reaction 1 showed a significant and low correlation with reaction 3 (r = 0.37). The effect size of the whole body reaction time was the largest. Whole body reaction movement, which is largely affected by the exercise output function, develops remarkably in childhood. Children who liked "tag" were faster in all reaction times. The children who chose "soccer" were faster in reactions 2 and 3. In contrast, children who liked "playing house" tended to have slower reaction times. Dynamic activities, such as tag and soccer, promote development of reaction speed and agility in movements involving the whole body. Preschool teachers and physical educators should re-examine the effect of tag and use it periodically as one of the exercise programs to avoid unexpected falls and injuries in everyday life.

Activation of RhoA, but Not Rac1, Mediates Early Stages of S1P-Induced Endothelial Barrier Enhancement.

Science.gov (United States)

Zhang, Xun E; Adderley, Shaquria P; Breslin, Jerome W

2016-01-01

Compromised endothelial barrier function is a hallmark of inflammation. Rho family GTPases are critical in regulating endothelial barrier function, yet their precise roles, particularly in sphingosine-1-phosphate (S1P)-induced endothelial barrier enhancement, remain elusive. Confluent cultures of human umbilical vein endothelial cells (HUVEC) or human dermal microvascular endothelial cells (HDMEC) were used to model the endothelial barrier. Barrier function was assessed by determining the transendothelial electrical resistance (TER) using an electrical cell-substrate impedance sensor (ECIS). The roles of Rac1 and RhoA were tested in S1P-induced barrier enhancement. The results show that pharmacologic inhibition of Rac1 with Z62954982 failed to block S1P-induced barrier enhancement. Likewise, expression of a dominant negative form of Rac1, or knockdown of native Rac1 with siRNA, failed to block S1P-induced elevations in TER. In contrast, blockade of RhoA with the combination of the inhibitors Rhosin and Y16 significantly reduced S1P-induced increases in TER. Assessment of RhoA activation in real time using a fluorescence resonance energy transfer (FRET) biosensor showed that S1P increased RhoA activation primarily at the edges of cells, near junctions. This was complemented by myosin light chain-2 phosphorylation at cell edges, and increased F-actin and vinculin near intercellular junctions, which could all be blocked with pharmacologic inhibition of RhoA. The results suggest that S1P causes activation of RhoA at the cell periphery, stimulating local activation of the actin cytoskeleton and focal adhesions, and resulting in endothelial barrier enhancement. S1P-induced Rac1 activation, however, does not appear to have a significant role in this process.

Activation of RhoA, but Not Rac1, Mediates Early Stages of S1P-Induced Endothelial Barrier Enhancement.

Directory of Open Access Journals (Sweden)

Xun E Zhang

Full Text Available Compromised endothelial barrier function is a hallmark of inflammation. Rho family GTPases are critical in regulating endothelial barrier function, yet their precise roles, particularly in sphingosine-1-phosphate (S1P-induced endothelial barrier enhancement, remain elusive. Confluent cultures of human umbilical vein endothelial cells (HUVEC or human dermal microvascular endothelial cells (HDMEC were used to model the endothelial barrier. Barrier function was assessed by determining the transendothelial electrical resistance (TER using an electrical cell-substrate impedance sensor (ECIS. The roles of Rac1 and RhoA were tested in S1P-induced barrier enhancement. The results show that pharmacologic inhibition of Rac1 with Z62954982 failed to block S1P-induced barrier enhancement. Likewise, expression of a dominant negative form of Rac1, or knockdown of native Rac1 with siRNA, failed to block S1P-induced elevations in TER. In contrast, blockade of RhoA with the combination of the inhibitors Rhosin and Y16 significantly reduced S1P-induced increases in TER. Assessment of RhoA activation in real time using a fluorescence resonance energy transfer (FRET biosensor showed that S1P increased RhoA activation primarily at the edges of cells, near junctions. This was complemented by myosin light chain-2 phosphorylation at cell edges, and increased F-actin and vinculin near intercellular junctions, which could all be blocked with pharmacologic inhibition of RhoA. The results suggest that S1P causes activation of RhoA at the cell periphery, stimulating local activation of the actin cytoskeleton and focal adhesions, and resulting in endothelial barrier enhancement. S1P-induced Rac1 activation, however, does not appear to have a significant role in this process.

Enrichment: CRISLA [chemical reaction by isotope selective activation] aims to reduce costs

International Nuclear Information System (INIS)

Eerkens, J.W.

1989-01-01

Every year, more than $3 billion is spent on enriching uranium. CRISLA (Chemical Reaction by Isotope Selective Activation) uses a laser-catalyzed chemical reaction which, its proponents claim, could substantially reduce these costs. In CRISLA, an infrared CO laser illuminates the intracavity reaction cell (IC) at a frequency tuned to excite primarily UF 6 . When UF 6 and co-reactant RX are passed through the IC, the tuned laser photons preferentially enhance the reaction of UF 6 with RX ten-thousand-fold over the thermal reaction rate. Thus the laser serves as an activator and the chemical energy for separation is largely chemical. (author)

Barriers to Physical Activity Among African American Women: An Integrative Review of the Literature

OpenAIRE

Joseph, Rodney P.; Ainsworth, Barbara E.; Keller, Colleen; Dodgson, Joan E

2015-01-01

A key aspect for researchers to consider when developing culturally appropriate physical activity (PA) interventions for African American (AA) women are the specific barriers AA women face that limit their participation in PA. Identification and critical examination of these barriers is the first step in developing comprehensive culturally relevant approaches to promote PA and help resolve PA-related health disparities in this underserved population. We conducted a systemati...

Short and long-term lifestyle coaching approaches used to address diverse participant barriers to weight loss and physical activity adherence.

Science.gov (United States)

Venditti, Elizabeth M; Wylie-Rosett, Judith; Delahanty, Linda M; Mele, Lisa; Hoskin, Mary A; Edelstein, Sharon L

2014-02-12

Individual barriers to weight loss and physical activity goals in the Diabetes Prevention Program, a randomized trial with 3.2 years average treatment duration, have not been previously reported. Evaluating barriers and the lifestyle coaching approaches used to improve adherence in a large, diverse participant cohort can inform dissemination efforts. Lifestyle coaches documented barriers and approaches after each session (mean session attendance = 50.3 ± 21.8). Subjects were 1076 intensive lifestyle participants (mean age = 50.6 years; mean BMI = 33.9 kg/m²; 68% female, 48% non-Caucasian). Barriers and approaches used to improve adherence were ranked by the percentage of the cohort for whom they applied. Barrier groupings were also analyzed in relation to baseline demographic characteristics. Top weight loss barriers reported were problems with self-monitoring (58%); social cues (58%); holidays (54%); low activity (48%); and internal cues (thought/mood) (44%). Top activity barriers were holidays (51%); time management (50%); internal cues (30%); illness (29%), and motivation (26%). The percentage of the cohort having any type of barrier increased over the long-term intervention period. A majority of the weight loss barriers were significantly associated with younger age, greater obesity, and non-Caucasian race/ethnicity (p-values vary). Physical activity barriers, particularly thought and mood cues, social cues and time management, physical injury or illness and access/weather, were most significantly associated with being female and obese (p  90% long term) and regularly reviewed self-monitoring skills. More costly approaches were used infrequently during the first 16 sessions (≤10%) but increased over 3.2 years. Behavioral problem solving approaches have short and long term dissemination potential for many kinds of participant barriers. Given minimal resources, increased attention to training lifestyle coaches in the consistent use of these

Enabling nucleophilic substitution reactions of activated alkyl fluorides through hydrogen bonding.

Science.gov (United States)

Champagne, Pier Alexandre; Pomarole, Julien; Thérien, Marie-Ève; Benhassine, Yasmine; Beaulieu, Samuel; Legault, Claude Y; Paquin, Jean-François

2013-05-03

It was discovered that the presence of water as a cosolvent enables the reaction of activated alkyl fluorides for bimolecular nucleophilic substitution reactions. DFT calculations show that activation proceeds through stabilization of the transition structure by a stronger F···H2O interaction and diminishing C-F bond elongation, and not simple transition state electrostatic stabilization. Overall, the findings put forward a distinct strategy for C-F bond activation through H-bonding.

Ghrelin ameliorates intestinal barrier dysfunction in experimental colitis by inhibiting the activation of nuclear factor-kappa B

International Nuclear Information System (INIS)

Cheng, Jian; Zhang, Lin; Dai, Weiqi; Mao, Yuqing; Li, Sainan; Wang, Jingjie; Li, Huanqing; Guo, Chuanyong; Fan, Xiaoming

2015-01-01

Aim: This study aimed to investigate the effect and underlying mechanism of ghrelin on intestinal barrier dysfunction in dextran sulfate sodium (DSS)-induced colitis. Methods and results: Acute colitis was induced in C57BL/6J mice by administering 2.5% DSS. Saline or 25, 125, 250 μg/kg ghrelin was administrated intraperitoneally (IP) to mice 1 day before colitis induction and on days 4, 5, and 6 after DSS administration. IP injection of a ghrelin receptor antagonist, [D-lys 3 ]-GHRP-6, was performed immediately prior to ghrelin injection. Ghrelin (125 or 250 μg/kg) could reduce the disease activity index, histological score, and myeloperoxidase activities in experimental colitis, and also prevented shortening of the colon. Ghrelin could prevent the reduction of transepithelial electrical resistance and tight junction expression, and bolstered tight junction structural integrity and regulated cytokine secretion. Ultimately, ghrelin inhibited nuclear factor kappa B (NF-κB), inhibitory κB-α, myosin light chain kinase, and phosphorylated myosin light chain 2 activation. Conclusions: Ghrelin prevented the breakdown of intestinal barrier function in DSS-induced colitis. The protective effects of ghrelin on intestinal barrier function were mediated by its receptor GHSR-1a. The inhibition of NF-κB activation might be part of the mechanism underlying the effects of ghrelin that protect against barrier dysfunction. - Highlights: • Ghrelin ameliorates intestinal barrier dysfunction in experimental colitis. • The effect of ghrelin is mediated by GHSR-1a. • Inhibition of NF-κB activation

Ghrelin ameliorates intestinal barrier dysfunction in experimental colitis by inhibiting the activation of nuclear factor-kappa B

Energy Technology Data Exchange (ETDEWEB)

Cheng, Jian; Zhang, Lin [Department of Gastroenterology, Jinshan Hospital of Fudan University, Shanghai (China); Dai, Weiqi [Department of Gastroenterology, Shanghai Tenth People' s Hospital, Tongji University, Shanghai (China); Mao, Yuqing [Department of Gastroenterology, Jinshan Hospital of Fudan University, Shanghai (China); Li, Sainan [Department of Gastroenterology, Shanghai Tenth People' s Hospital, Tongji University, Shanghai (China); Wang, Jingjie; Li, Huanqing [Department of Gastroenterology, Jinshan Hospital of Fudan University, Shanghai (China); Guo, Chuanyong [Department of Gastroenterology, Shanghai Tenth People' s Hospital, Tongji University, Shanghai (China); Fan, Xiaoming, E-mail: xiaomingfan57@sina.com [Department of Gastroenterology, Jinshan Hospital of Fudan University, Shanghai (China)

2015-02-27

Aim: This study aimed to investigate the effect and underlying mechanism of ghrelin on intestinal barrier dysfunction in dextran sulfate sodium (DSS)-induced colitis. Methods and results: Acute colitis was induced in C57BL/6J mice by administering 2.5% DSS. Saline or 25, 125, 250 μg/kg ghrelin was administrated intraperitoneally (IP) to mice 1 day before colitis induction and on days 4, 5, and 6 after DSS administration. IP injection of a ghrelin receptor antagonist, [D-lys{sup 3}]-GHRP-6, was performed immediately prior to ghrelin injection. Ghrelin (125 or 250 μg/kg) could reduce the disease activity index, histological score, and myeloperoxidase activities in experimental colitis, and also prevented shortening of the colon. Ghrelin could prevent the reduction of transepithelial electrical resistance and tight junction expression, and bolstered tight junction structural integrity and regulated cytokine secretion. Ultimately, ghrelin inhibited nuclear factor kappa B (NF-κB), inhibitory κB-α, myosin light chain kinase, and phosphorylated myosin light chain 2 activation. Conclusions: Ghrelin prevented the breakdown of intestinal barrier function in DSS-induced colitis. The protective effects of ghrelin on intestinal barrier function were mediated by its receptor GHSR-1a. The inhibition of NF-κB activation might be part of the mechanism underlying the effects of ghrelin that protect against barrier dysfunction. - Highlights: • Ghrelin ameliorates intestinal barrier dysfunction in experimental colitis. • The effect of ghrelin is mediated by GHSR-1a. • Inhibition of NF-κB activation.

Nuclear reorganization barriers to electron transfer

International Nuclear Information System (INIS)

Sutin, N.; Brunschwig, B.S.; Creutz, C.; Winkler, J.R.

1988-01-01

The nuclear barrier to electron transfer arises from the need for reorganization of intramolecular and solvent internuclear distances prior to electron transfer. For reactions with relatively small driving force (''normal'' free-energy region) the nuclear factors and rates increase as intrinsic inner-shell and outer-shell barriers decrease; this is illustrated by data for transition metal complexes in their ground electronic states. By contrast, in the inverted free-energy region, rates and nuclear factors decrease with decreasing ''intrinsic'' barriers; this is illustrated by data for the decay of charge-transfer excited states. Several approaches to the evaluation of the outer-shell barrier are explored in an investigation of the distance dependence of the nuclear factor in intramolecular electron-transfer processes. 39 refs., 14 figs., 3 tabs

Perceived barriers and enablers of physical activity in postpartum women: a qualitative approach.

Science.gov (United States)

Saligheh, Maryam; McNamara, Beverley; Rooney, Rosanna

2016-06-02

Postpartum women's recovery from birth can be assisted through increased physical activity (PA). However, women face substantial barriers to participating in exercise and require support to enable them to benefit from increased PA. This study sought to explore women's beliefs about and experiences of PA and exercise during the 6 weeks to 12 months postpartum period. A cohort of 14 postpartum women from a survey study of the barriers and enablers to exercise participation agreed to take part in interview sessions to provide an in-depth understanding of the women's perceptions of the postpartum period and their physical activity during this time. Findings are presented with reference to the social ecological framework and indicate postpartum women face substantial personal and environmental barriers to PA and exercise participation: fatigue, a lack of motivation and confidence, substantial time constraints, lack of access to affordable and appropriate activities and poor access to public transport. In contrast, enablers such as possessing greater social support, in particular partner support, improved PA and exercise participation. The findings encourage facilitation of exercise through mothers' groups, mothers' exercise clubs or postnatal classes suggesting behavioral and social change is needed. Interaction between individuals, community, organizations and policy makers is required. In addition, the provision of specifically tailored and appropriate exercise programs could potentially enable increased PA in postpartum women, thereby improving their health.

Barriers and Facilitators of Breasteeding for Primiparous Active Duty Military Mothers: A Qualitative Study

National Research Council Canada - National Science Library

Bristow, Kristine

1999-01-01

.... This descriptive study describes the barriers and facilitators of breastfeeding for primiparous active duty military mothers, from their perspective, using a Husserlian phenomenological approach...

Understanding exercise self-efficacy and barriers to leisure-time physical activity among postnatal women.

Science.gov (United States)

Cramp, Anita G; Bray, Steven R

2011-07-01

Studies have demonstrated that postnatal women are at high risk for physical inactivity and generally show lower levels of leisure-time physical activity (LTPA) compared to prepregnancy. The overall purpose of the current study was to investigate social cognitive correlates of LTPA among postnatal women during a 6-month period following childbirth. A total of 230 women (mean age = 30.9) provided descriptive data regarding barriers to LTPA and completed measures of LTPA and self-efficacy (exercise and barrier) for at least one of the study data collection periods. A total of 1,520 barriers were content analyzed. Both exercise and barrier self-efficacy were positively associated with subsequent LTPA. Exercise self-efficacy at postnatal week 12 predicted LTPA from postnatal weeks 12 to 18 (β = .40, R (2) = .18) and exercise self-efficacy at postnatal week 24 predicted LTPA during weeks 24-30 (β = .49, R (2) = .30). Barrier self-efficacy at week 18 predicted LTPA from weeks 18 to 24 (β = .33, R (2) = .13). The results of the study identify a number of barriers to LTPA at multiple time points closely following childbirth which may hinder initiation, resumption or maintenance of LTPA. The results also suggest that higher levels of exercise and barrier self-efficacy are prospectively associated with higher levels of LTPA in the early postnatal period. Future interventions should be designed to investigate causal effects of developing participants' exercise and barrier self-efficacy for promoting and maintaining LTPA during the postnatal period.

Barriers and motivators for physical activity among overweight and obese people with type 2 diabetes

DEFF Research Database (Denmark)

Lidegaard, Lærke; Schwennesen, Nete; Willaing, Ingrid

2016-01-01

Aim To explore barriers to and motivators for physical activity in a group of overweight and obese individuals with dysregulated Type 2 diabetes. Methods Data were collected from the Steno Diabetes Centre's outpatient clinic in Denmark. Four focus groups were conducted including 28 individuals...... with Type 2 diabetes aged 39–71 years. The facilitators used open-ended questions and probes such as images, statements and quotations about physical activity to foster active participation and interaction among participants. Focus groups were recorded on video and the discussions were transcribed...... and analysed thematically. Results We identified four main themes: 1) the body as a barrier to physical activity because of functional limitations; 2) logistical challenges, including lack of time and awareness of where to exercise in the local area; 3) being physically active with others, providing a sense...

Attitudes, barriers and enablers to physical activity in pregnant women: a systematic review

Directory of Open Access Journals (Sweden)

Anne L Harrison

2018-01-01

Registration: PROSPERO CRD42016037643. [Harrison AL, Taylor NF, Shields N, Frawley HC (2018 Attitudes, barriers and enablers to physical activity in pregnant women: a systematic review. Journal of Physiotherapy 64: 24–32

Reactive Membrane Barriers for Containment of Subsurface Contamination

Energy Technology Data Exchange (ETDEWEB)

William A. Arnold; Edward L. Cussler

2007-02-26

The overall goal of this project was to develop reactive membrane barriers--a new and flexible technique to contain and stabilize subsurface contaminants. Polymer membranes will leak once a contaminant is able to diffuse through the membrane. By incorporating a reactive material in the polymer, however, the contaminant is degraded or immobilized within the membrane. These processes increase the time for contaminants to breakthrough the barrier (i.e. the lag time) and can dramatically extend barrier lifetimes. In this work, reactive barrier membranes containing zero-valent iron (Fe{sup 0}) or crystalline silicotitanate (CST) were developed to prevent the migration of chlorinated solvents and cesium-137, respectively. These studies were complemented by the development of models quantifying the leakage/kill time of reactive membranes and describing the behavior of products produced via the reactions within the membranes. First, poly(vinyl alcohol) (PVA) membranes containing Fe{sup 0} and CST were prepared and tested. Although PVA is not useful in practical applications, it allows experiments to be performed rapidly and the results to be compared to theory. For copper ions (Cu{sup 2+}) and carbon tetrachloride, the barrier was effective, increasing the time to breakthrough over 300 times. Even better performance was expected, and the percentage of the iron used in the reaction with the contaminants was determined. For cesium, the CST laden membranes increased lag times more than 30 times, and performed better than theoretical predictions. A modified theory was developed for ion exchangers in reactive membranes to explain this result. With the PVA membranes, the effect of a groundwater matrix on barrier performance was tested. Using Hanford groundwater, the performance of Fe{sup 0} barriers decreased compared to solutions containing a pH buffer and high levels of chloride (both of which promote iron reactivity). For the CST bearing membrane, performance improved by a

Reactive Membrane Barriers for Containment of Subsurface Contamination

International Nuclear Information System (INIS)

William A. Arnold; Edward L. Cussler

2007-01-01

The overall goal of this project was to develop reactive membrane barriers--a new and flexible technique to contain and stabilize subsurface contaminants. Polymer membranes will leak once a contaminant is able to diffuse through the membrane. By incorporating a reactive material in the polymer, however, the contaminant is degraded or immobilized within the membrane. These processes increase the time for contaminants to breakthrough the barrier (i.e. the lag time) and can dramatically extend barrier lifetimes. In this work, reactive barrier membranes containing zero-valent iron (Fe 0 ) or crystalline silicotitanate (CST) were developed to prevent the migration of chlorinated solvents and cesium-137, respectively. These studies were complemented by the development of models quantifying the leakage/kill time of reactive membranes and describing the behavior of products produced via the reactions within the membranes. First, poly(vinyl alcohol) (PVA) membranes containing Fe 0 and CST were prepared and tested. Although PVA is not useful in practical applications, it allows experiments to be performed rapidly and the results to be compared to theory. For copper ions (Cu 2+ ) and carbon tetrachloride, the barrier was effective, increasing the time to breakthrough over 300 times. Even better performance was expected, and the percentage of the iron used in the reaction with the contaminants was determined. For cesium, the CST laden membranes increased lag times more than 30 times, and performed better than theoretical predictions. A modified theory was developed for ion exchangers in reactive membranes to explain this result. With the PVA membranes, the effect of a groundwater matrix on barrier performance was tested. Using Hanford groundwater, the performance of Fe 0 barriers decreased compared to solutions containing a pH buffer and high levels of chloride (both of which promote iron reactivity). For the CST bearing membrane, performance improved by a factor of three when

Solvent effects and potential of mean force study of the SN2 reaction of CH3+CN‑ in water

Science.gov (United States)

Li, Chen; Liu, Peng; Li, Yongfang; Wang, Dunyou

2018-03-01

We used a combined quantum mechanics and molecular mechanics (QM/MM) method to investigate the solvent effects and potential of mean force of the CH3F+CN‑ reaction in water. Comparing to gas phase, the water solution substantially affects the structures of the stationary points along the reaction path. We quantitatively obtained the solvent effects’ contributions to the reaction: 1.7 kcal/mol to the activation barrier and ‑26.0 kcal/mol to the reaction free energy. The potential mean of force calculated with the density functional theory/MM theory has a barrier height at 19.7 kcal/mol, consistent with the experimental result at 23.0 kcal/mol; the calculated reaction free energy at ‑43.5 kcal/mol is also consistent with the one estimated based on the gas-phase data at ‑39.7 kcal/mol. Project supported by the National Natural Science Foundation of China (Grant No. 11774206) and Taishan Scholarship Fund from Shandong Province, China.

General Practitioners' Barriers to Prescribe Physical Activity: The Dark Side of the Cluster Effects on the Physical Activity of Their Type 2 Diabetes Patients.

Science.gov (United States)

Lanhers, Charlotte; Duclos, Martine; Guttmann, Aline; Coudeyre, Emmanuel; Pereira, Bruno; Ouchchane, Lemlih

2015-01-01

To describe barriers to physical activity (PA) in type 2 diabetes patients and their general practitioners (GPs), looking for practitioner's influence on PA practice of their patients. We conducted a cross-sectional study on GPs (n = 48) and their type 2 diabetes patients (n = 369) measuring respectively barriers to prescribe and practice PA using a self-assessment questionnaire: barriers to physical activity in diabetes (BAPAD). Statistical analysis was performed accounting hierarchical data structure. Similar practitioner's patients were considered a cluster sharing common patterns. The higher the patient's BAPAD score, the higher the barriers to PA, the higher the risk to declare practicing no PA (pbarriers to physical activity, have a higher PA level and a better glycemic control. An important and deleterious cluster effect between GPs and their patients is demonstrated: the higher the GP's BAPAD score, the higher the type 2 diabetes patients' BAPAD score. This important cluster effect might designate GPs as a relevant lever for future interventions regarding patient's education towards PA and type 2 diabetes management.

The barrier to ice nucleation in monatomic water

Science.gov (United States)

Prestipino, Santi

2018-03-01

Crystallization from a supercooled liquid initially proceeds via the formation of a small solid embryo (nucleus), which requires surmounting an activation barrier. This phenomenon is most easily studied by numerical simulation, using specialized biased-sampling techniques to overcome the limitations imposed by the rarity of nucleation events. Here, I focus on the barrier to homogeneous ice nucleation in supercooled water, as represented by the monatomic-water model, which in the bulk exhibits a complex interplay between different ice structures. I consider various protocols to identify solidlike particles on a computer, which perform well enough for the Lennard-Jones model, and compare their respective impact on the shape and height of the nucleation barrier. It turns out that the effect is stronger on the nucleus size than on the barrier height. As a by-product of the analysis, I determine the structure of the nucleation cluster, finding that the relative amount of ice phases in the cluster heavily depends on the method used for classifying solidlike particles. Moreover, the phase which is most favored during the earlier stages of crystallization may happen, depending on the nucleation coordinate adopted, to be different from the stable polymorph. Therefore, the quality of a reaction coordinate cannot be assessed simply on the basis of the barrier height obtained. I explain how this outcome is possible and why it just points out the shortcoming of collective variables appropriate to simple fluids in providing a robust method of particle classification for monatomic water.

Hydrogen transfer reactions of interstellar Complex Organic Molecules

Science.gov (United States)

Álvarez-Barcia, S.; Russ, P.; Kästner, J.; Lamberts, T.

2018-06-01

Radical recombination has been proposed to lead to the formation of complex organic molecules (COMs) in CO-rich ices in the early stages of star formation. These COMs can then undergo hydrogen addition and abstraction reactions leading to a higher or lower degree of saturation. Here, we have studied 14 hydrogen transfer reactions for the molecules glyoxal, glycoaldehyde, ethylene glycol, and methylformate and an additional three reactions where CHnO fragments are involved. Over-the-barrier reactions are possible only if tunneling is invoked in the description at low temperature. Therefore the rate constants for the studied reactions are calculated using instanton theory that takes quantum effects into account inherently. The reactions were characterized in the gas phase, but this is expected to yield meaningful results for CO-rich ices due to the minimal alteration of reaction landscapes by the CO molecules. We found that rate constants should not be extrapolated based on the height of the barrier alone, since the shape of the barrier plays an increasingly larger role at decreasing temperature. It is neither possible to predict rate constants based only on considering the type of reaction, the specific reactants and functional groups play a crucial role. Within a single molecule, though, hydrogen abstraction from an aldehyde group seems to be always faster than hydrogen addition to the same carbon atom. Reactions that involve heavy-atom tunneling, e.g., breaking or forming a C-C or C-O bond, have rate constants that are much lower than those where H transfer is involved.

Barriers to Physical Activity for People with Long-Term Neurological Conditions: A Review Study

Science.gov (United States)

Mulligan, Hilda F.; Hale, Leigh A.; Whitehead, Lisa; Baxter, G. David

2012-01-01

People with disability are insufficiently physically active for health. This study identified the volume, quality, and findings of research that exposes environmental and personal barriers of physical activity participation for people with neurological conditions. CINAHL, Sport Discus, EMBASE, Medline, and AMED were systematically searched between…

Out-of-equilibrium catalysis of chemical reactions by electronic tunnel currents.

Science.gov (United States)

Dzhioev, Alan A; Kosov, Daniel S; von Oppen, Felix

2013-04-07

We present an escape rate theory for current-induced chemical reactions. We use Keldysh nonequilibrium Green's functions to derive a Langevin equation for the reaction coordinate. Due to the out of equilibrium electronic degrees of freedom, the friction, noise, and effective temperature in the Langevin equation depend locally on the reaction coordinate. As an example, we consider the dissociation of diatomic molecules induced by the electronic current from a scanning tunnelling microscope tip. In the resonant tunnelling regime, the molecular dissociation involves two processes which are intricately interconnected: a modification of the potential energy barrier and heating of the molecule. The decrease of the molecular barrier (i.e., the current induced catalytic reduction of the barrier) accompanied by the appearance of the effective, reaction-coordinate-dependent temperature is an alternative mechanism for current-induced chemical reactions, which is distinctly different from the usual paradigm of pumping vibrational degrees of freedom.

Are the barriers for physical activity practice equal for all peripheral artery disease patients?

Science.gov (United States)

Cavalcante, Bruno R; Farah, Breno Q; dos A Barbosa, João Paulo; Cucato, Gabriel Grizzo; da Rocha Chehuen, Marcel; da Silva Santana, Fábio; Wolosker, Nelson; de Moraes Forjaz, Cláudia Lúcia; Ritti-Dias, Raphael M

2015-02-01

To investigate barriers to physical activity related to the sociodemographic comorbidities and clinical variables of patients with intermittent claudication. Cross-sectional study. Ambulatory care. The medical histories of patients (N=145) aged ≥50 years with intermittent claudication were examined. Not applicable. Sociodemographic data (sex, race, level of education, socioeconomic status, marital status), comorbidities (overweight, hypertension, dyslipidemia, diabetes, currently smoking, heart disease), and clinical variables (initial claudication distance, total walking distance, ankle-brachial index). Information on personal and environmental barriers was obtained by questionnaire. Low economic status was most associated with "being afraid of falling" (odd ratios [OR]=2.22; 95% confidence interval [CI], 1.08-4.54). Low education level was most associated with "lack of street pedestrian crossing" (OR=3.34; 95% CI, 1.48-7.52). Diabetes was associated with lack of energy (OR=3.38; 95% CI, 1.68-6.79) and other medical conditions (eg, arthritis, angina) (OR=3.44; 95% CI, 1.65-7.16). Ankle brachial index was associated with "some difficulty in getting to a place where physical activity can be performed" (OR=2.75; 95% CI, 1.22-6.21). Walking capacity was strongly associated with barriers relating to leg pain (OR=7.39; 95% CI, 1.66-32.88). Older patients, those with a low education level, patients with diabetes, low ankle brachial index, and those with a lower walking capacity are more likely to experience barriers to physical activity. Copyright © 2015 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

Transient change in the shape of premixed burner flame with the superposition of pulsed dielectric barrier discharge

Science.gov (United States)

Zaima, Kazunori; Sasaki, Koichi

2016-08-01

We investigated the transient phenomena in a premixed burner flame with the superposition of a pulsed dielectric barrier discharge (DBD). The length of the flame was shortened by the superposition of DBD, indicating the activation of combustion chemical reactions with the help of the plasma. In addition, we observed the modulation of the top position of the unburned gas region and the formations of local minimums in the axial distribution of the optical emission intensity of OH. These experimental results reveal the oscillation of the rates of combustion chemical reactions as a response to the activation by pulsed DBD. The cycle of the oscillation was 0.18-0.2 ms, which could be understood as the eigenfrequency of the plasma-assisted combustion reaction system.

Structure information from fusion barriers

Indian Academy of Sciences (India)

Pb, using the coupled reaction channel (CRC) method and correct structure information, have been analysed. The barrier distributions derived from these excitation functions including many of the significant channels are featureless, although these channels have considerable effects on the fusion excitation function.

Motivators and Barriers to Engaging in Healthy Eating and Physical Activity.

Science.gov (United States)

Ashton, Lee M; Hutchesson, Melinda J; Rollo, Megan E; Morgan, Philip J; Collins, Clare E

2017-03-01

Many Australian young men (18-25 years) fail to meet recommendations in national dietary or physical activity (PA) guidelines. However, there is a lack of understanding of their perspectives on PA and diet to inform intervention design. This study examined young men's motivators and barriers to healthy eating and PA, along with differences by demographic and behavioral factors. A cross-sectional online survey was completed by 282 men aged 18 to 25 years in Australia. Results identified the most common motivators for healthy eating included improving health (63.5%), body image (52.3%), and increasing energy (32.1%). Motivators for PA included improving body image (44.6%), fitness (44.2%), and health (41.0%). Common barriers to healthy eating were access to unhealthy foods (61.1%), time to cook/prepare healthy foods (55.0%), and motivation to cook healthy foods (50.7%). Barriers for PA included motivation (66.3%), time (57.8%), and cost of equipment/facilities (33.3%). Significant differences ( p motivators to healthy eating and/or PA were identified for BMI category, marital status, PA level, alcohol intake, and stress levels. Significant differences were identified for barriers to healthy eating and/or PA by BMI, PA level, stress, and fruit and vegetable intake, assessed using Pearson's chi-square test. Findings suggest that promotion of benefits related to health, appearance/body image, increased energy and fitness, and addressing key barriers including motivation, time, financial restraints, and accessibility of unhealthy foods, could engage young men in improving lifestyle behaviors. Differences by demographic and behavioral factors suggest development of tailored programs to address diversity among young men may be required.

Modeling the mechanism of glycosylation reactions between ethanol, 1,2-ethanediol and methoxymethanol.

Science.gov (United States)

Azofra, Luis Miguel; Alkorta, Ibon; Toro-Labbé, Alejandro; Elguero, José

2013-09-07

The mechanism of the S(N)2 model glycosylation reaction between ethanol, 1,2-ethanediol and methoxymethanol has been studied theoretically at the B3LYP/6-311+G(d,p) computational level. Three different types of reactions have been explored: (i) the exchange of hydroxyl groups between these model systems; (ii) the basic catalysis reactions by combination of the substrates as glycosyl donors (neutral species) and acceptors (enolate species); and (iii) the effect on the reaction profile of an explicit H2O molecule in the reactions considered in (ii). The reaction force, the electronic chemical potential and the reaction electronic flux have been characterized for the reaction path in each case. Energy calculations show that methoxymethanol is the worst glycosyl donor model among the ones studied here, while 1,2-ethanediol is the best, having the lowest activation barrier of 74.7 kJ mol(-1) for the reaction between this one and the ethanolate as the glycosyl acceptor model. In general, the presence of direct interactions between the atoms involved in the penta-coordinated TS increases the activation energies of the processes.

Emotional Barriers to Successful Reemployment: Implications for Counselors.

Science.gov (United States)

Guindon, Mary H.; Smith, Barrett

2002-01-01

Common responses to job loss include stress reactions, depression and anxiety, and lowered self-esteem. This article describes these common reactions to job loss and unemployment, explains how to recognize their symptoms, and discusses ways counselors can address these emotional barriers to finding meaningful employment. (Contains 50 references.)…

Barrier for cold-fusion production of superheavy elements

International Nuclear Information System (INIS)

Ichikawa, Takatoshi; Iwamoto, Akira; Moeller, Peter; Sierk, Arnold J.

2005-01-01

We estimate the fusion-barrier height B fu (two-body) for approaching ions in cold-fusion reactions in a model where the projectile deformation and quadrupole zero-point vibrational energy are taken into account. This barrier height is defined as the barrier energy at the target and projectile separation distance where an original oblate deformation of projectile and/or target caused by a repulsive Coulomb force turns into a large prolate deformation caused by the attractive nuclear force as the target and projectile come closer. The instability develops before touching because the attractive short-range nuclear force overcomes the repulsive Coulomb force and the shape-stabilizing effect of shell structure. The shell structure of the doubly magic 208 Pb target is sufficiently strong that its shape remains very close to spherical in all cases studied here. The fusion potential for approaching ions in the two-body channel is calculated in the macroscopic-microscopic model with the quadrupole vibrational zero-point energy obtained in the WKB approximation. We compare our results with data from 10 experimental cold-fusion reactions and with the Bass barriers. Differences and similarities between the Yukawa-plus-exponential model and the Bass model are discussed. We also calculate five-dimensional potential-energy surfaces for the single compound system and show that well-established fission and fusion valleys are both present. For heavy systems, B fu (two-body) becomes lower than the fission barrier just beyond the ground state of the compound system. In the vicinity of this transition, the optimum collision energy for formation of evaporation residues can be expected to depend in a delicate fashion on the interplay among B fu (two-body) , the fusion valley, the fission barrier of the compound system, and the one- and two-neutron separation energies S 1n and S 2n . We discuss these issues in detail and calculate fission-barrier heights. Except for reactions in which

Electroless Ni-Mo-P diffusion barriers with Pd-activated self-assembled monolayer on SiO2

International Nuclear Information System (INIS)

Liu Dianlong; Yang Zhigang; Zhang Chi

2010-01-01

Ternary Ni-based amorphous films can serve as a diffusion barrier layer for Cu interconnects in ultralarge-scale integration (ULSI) applications. In this paper, electroless Ni-Mo-P films deposited on SiO 2 layer without sputtered seed layer were prepared by using Pd-activated self-assembled monolayer (SAM). The solutions and operating conditions for pretreatment and deposition were presented, and the formation of Pd-activated SAM was demonstrated by XPS (X-ray photoelectron spectroscopy) analysis and BSE (back-scattered electron) observation. The effects of the concentration of Na 2 MoO 4 added in electrolytes, pH value, and bath temperature on the surface morphology and compositions of Ni-Mo-P films were investigated. The microstructures, diffusion barrier property, electrical resistivity, and adhesion were also examined. Based on the experimental results, the Ni-Mo-P alloys produced by using Pd-activated SAM had an amorphous or amorphous-like structure, and possessed good performance as diffusion barrier layer.

The prevalence of barriers for Colombian college students engaging in physical activity.

Science.gov (United States)

Ramírez-Vélez, Robinson; Tordecilla-Sanders, Alejandra; Laverde, David; Hernández-Novoa, Juan Gilberto; Ríos, Marcelo; Rubio, Fernando; Correa-Bautista, Jorge Enrique; Martinez-Torres, Javier

2014-09-18

To investigate the prevalence of barriers and their association with Colombia college students engaging in PA. A total of 5,663 students (3,348 male) from three cities in Colombia. In fall 2013, students voluntarily completed a demographic questionnaire, Barriers to Being Active Quiz. Logistic regression analysis of each barrier (adjusted for confusion variables: gender, age and BMI) was used for verifying such association. The most prevalent barriers in overweight individuals were "fear of injury" (87.0%), "lack of skill" (79.8%) and "lack of resources" (64.3%). The group of females revealed a protective association regarding "lack of time" (OR=0.53: 0.47-0.60 95%CI), "social influence" (OR=0.67: 0.60-0.75 95%CI), "lack of energy" (OR=0.54: 0.49-0.61 95%CI), "lack of willpower" (OR=0.57: 0.51- 0.64 95%CI), "lack of skill" (OR=0.76: 0.66-0.87 95%CI) and "lack of resources" (OR=0.79: 0.71-0.89 95%CI). Such observation also appeared in the 20- to 23-yearold age group concerning "social influence" (OR=0.83: 0.74-0.94 95%CI) and in those aged over 23-years-old (OR=0.86: 0.74-0.99 95%CI) regarding "lack of energy". A significant prevalence was found regarding self-perception of barriers leading to students ceasing to engage in PA. Copyright AULA MEDICA EDICIONES 2014. Published by AULA MEDICA. All rights reserved.

Direct gas-phase epoxidation of propylene to propylene oxide through radical reactions: A theoretical study

Science.gov (United States)

Kizilkaya, Ali Can; Fellah, Mehmet Ferdi; Onal, Isik

2010-03-01

The gas-phase radical chain reactions which utilize O 2 as the oxidant to produce propylene oxide (PO) are investigated through theoretical calculations. The transition states and energy profiles were obtained for each path. The rate constants were also calculated. The energetics for the competing pathways indicate that PO can be formed selectively due to its relatively low activation barrier (9.3 kcal/mol) which is in a good agreement with the experimental value (11 kcal/mol) of gas-phase propylene epoxidation. The formation of the acrolein and combustion products have relatively high activation barriers and are not favored. These results also support the recent experimental findings.

Modifiable barriers to leisure-time physical activity during pregnancy: a qualitative study investigating first time mother's views and experiences.

Science.gov (United States)

Connelly, Megan; Brown, Helen; van der Pligt, Paige; Teychenne, Megan

2015-04-22

Evidence suggests physical activity often declines during pregnancy, however explanations for the decline are not well understood. The aim of this study was to identify modifiable barriers to leisure-time physical activity among women who did not meet physical activity guidelines during pregnancy. Analyses were based on data from 133 mothers (~3-months postpartum) who were recruited from the Melbourne InFANT Extend study (2012/2013). Women completed a self-report survey at baseline in which they reported their leisure-time physical activity levels during pregnancy as well provided an open-ended written response regarding the key barriers that they perceived prevented them from meeting the physical activity guidelines during their pregnancy. Thematic analyses were conducted to identify key themes. The qualitative data revealed six themes relating to the barriers of leisure-time physical activity during pregnancy. These included work-related factors (most commonly reported), tiredness, pregnancy-related symptoms, being active but not meeting the guidelines, lack of motivation, and a lack of knowledge of recommendations. Considering work-related barriers were suggested to be key factors to preventing women from meeting the physical activity guidelines during pregnancy, workplace interventions aimed at providing time management skills along with supporting physical activity programs for pregnant workers should be considered. Such interventions should also incorporate knowledge and education components, providing advice for undertaking leisure-time physical activity during pregnancy.

Nuclear halo and its related reactions

International Nuclear Information System (INIS)

Zhang Huanqiao

2005-01-01

nuclear halo in terms of the analytical expressions of the expectation value for the operator r 2 in a finite square-well potential. Nuclear reactions induced by halo and weekly bound nuclei are a topic of current interest. We have measured the complete fusion cross sections of 6 Li+ 208 Pb and found the fusion cross sections above the Coulomb barrier are suppressed due to the breakup effects of weekly bound projectile 6 Li. We have also measured the elastic and quasi-elastic excitation functions of 6,7 Li, 9 Be+ 208 Pb, 209 Ri. From these excitation functions, barrier distributions are extracted and compared with the predictions of the coupled-channels model. It is found that the barrier distributions are somehow broaden and shift to lower energies which may be a signature of the breakup effects of the weekly bound projectiles. Gomes et al. study the behavior of the fusion, breakup, reaction, and elastic scattering of different projectiles on 64 Zn at near and above barrier energies. They found that the elastic (noncapture) breakup cross section is important at energies close to and above the Coulomb barrier and increases the reaction cross sections. In addition, they show that the breakup process at near and below barrier energies is responsible for the vanishing of the usual threshold anomaly of the optical and gives rise to a new type of anomaly. Recently, Newton et al. systematically analyzed the high precision fusion cross sections for Z p Z t p Z t 48 Ca+ 90,96 Zr at the XTU Tandem accelerator facility of the Laboratori Nazionali di Legnaro, Italy. The comparison of experimental 40,48 Ca+ 90,96 Zr fusion data shows that fusion of 40 Ca+ 96 Zr is much enhanced due to the positive Q-values of the transfer channels. The much larger enhancement for the 40 Ca+ 96 Zr as compared to other three systems clearly indicates that neutron transfer with the positive Q-value should play a significant role in sub-barrier fusion. In order to extract the information on the complex

Promoting youth physical activity in rural southern communities: practitioner perceptions of environmental opportunities and barriers.

Science.gov (United States)

Edwards, Michael B; Theriault, Daniel S; Shores, Kindal A; Melton, Karen M

2014-01-01

Research on youth physical activity has focused on urban areas. Rural adolescents are more likely to be physically inactive than urban youth, contributing to higher risk of obesity and chronic diseases. Study objectives were to: (1) identify perceived opportunities and barriers to youth physical activity within a rural area and (2) identify rural community characteristics that facilitate or inhibit efforts to promote youth physical activity. Thirty in-depth interviews were conducted with expert informants in 2 rural southern US counties. Interviewees were recruited from diverse positions across multiple sectors based on their expert knowledge of community policies and programs for youth physical activity. Informants saw ball fields, natural amenities, and school sports as primary resources for youth physical activity, but they were divided on whether opportunities were abundant or scarce. Physical distance, social isolation, lack of community offerings, and transportation were identified as key barriers. Local social networks facilitated political action and volunteer recruitment to support programs. However, communities often lacked human capital to sustain initiatives. Racial divisions influenced perceptions of opportunities. Despite divisions, there were also examples of pooling resources to create and sustain physical activity opportunities. Developing partnerships and leveraging local resources may be essential to overcoming barriers for physical activity promotion in rural areas. Involvement of church leaders, school officials, health care workers, and cooperative extension is likely needed to establish and sustain youth rural physical activity programs. Allocating resources to existing community personnel and volunteers for continuing education may be valuable. © 2014 National Rural Health Association.

Everyday physical activity in ambulatory heart transplant candidates: the role of expected health benefits, social support, and potential barriers.

Science.gov (United States)

Gerhardt, Andreas; Weidner, Gerdi; Grassmann, Mariel; Spaderna, Heike

2014-04-01

Physical activity (PA) is recommended for stable patients with advanced heart failure (HF). We evaluated expected health benefits of PA and social support as facilitators of PA, and physical symptom distress and psychological distress (depression, anxiety) as barriers to PA. Additionally, we investigated if facilitators of PA are of particular importance for patients who report barriers. We analyzed data assessed at time of waitlisting in 231 ambulatory patients (53.4 ± 10.3 years, 18 % women) who were enrolled in the multisite Waiting for a New Heart Study in 1 Austrian and 16 German hospitals. Self-reported everyday PA scores (number of activities, duration of activities) was regressed on demographic characteristics and indicators of disease severity (ejection fraction, peak oxygen consumption), facilitators (expected health benefits of PA, perceived emotional support, perceived support for PA), and barriers to PA (physical symptom distress, psychological distress). Interaction terms of facilitators with barriers were also examined. PA was positively associated with higher peak oxygen consumption, validating self-reported PA. Regarding facilitators, expected health benefits of PA were independently associated with higher PA (p values barriers, depression tended to be associated with fewer activities (p = 0.068). However, in the presence of barriers (depression, physical symptoms), feeling supported for being physically active was positively associated with PA (p values < 0.05). Interventions to improve PA may benefit from strengthening positive expectations of health outcomes associated with everyday PA and fostering PA-specific social support for those distressed by HF symptoms or depression.

Highly Stable and Active Catalyst for Sabatier Reactions

Science.gov (United States)

Hu, Jianli; Brooks, Kriston P.

2012-01-01

Highly active Ru/TiO2 catalysts for Sabatier reaction have been developed. The catalysts have shown to be stable under repeated shutting down/startup conditions. When the Ru/TiO2 catalyst is coated on the engineered substrate Fe-CrAlY felt, activity enhancement is more than doubled when compared with an identically prepared engineered catalyst made from commercial Degussa catalyst. Also, bimetallic Ru-Rh/TiO2 catalysts show high activity at high throughput.

Minimum recommended physical activity, and perceived barriers and benefits of exercise in methadone maintained persons.

Science.gov (United States)

Caviness, Celeste M; Bird, Jessica L; Anderson, Bradley J; Abrantes, Ana M; Stein, Michael D

2013-04-01

Methadone-maintained persons are at increased risk for many physical and mental health disorders compared to the general population. Increased physical activity could offset these risks. We assessed physical activity level, and perceived benefits and barriers to exercise in a group of 305 methadone-maintained smokers. Mean participant age was 39.9 years, 50.2% were male, 79.7% were non-Hispanic White, and mean body mass index was 29.8. Nearly 45% endorsed fair or poor physical health. Although participants perceived many benefits of exercise and few barriers, only 38% of participants met weekly recommendations for physical activity, and nearly 25% reported no physical activity. Those who met recommended guidelines were significantly more likely to endorse relapse prevention as a benefit of exercise. Motivating MMT patients to increase physical activity could have important physical, mental health, and drug treatment benefits. Copyright © 2013 Elsevier Inc. All rights reserved.

Barrier experiment: Shock initiation under complex loading

Energy Technology Data Exchange (ETDEWEB)

Menikoff, Ralph [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2016-01-12

The barrier experiments are a variant of the gap test; a detonation wave in a donor HE impacts a barrier and drives a shock wave into an acceptor HE. The question we ask is: What is the trade-off between the barrier material and threshold barrier thickness to prevent the acceptor from detonating. This can be viewed from the perspective of shock initiation of the acceptor subject to a complex pressure drive condition. Here we consider key factors which affect whether or not the acceptor undergoes a shock-to-detonation transition. These include the following: shock impedance matches for the donor detonation wave into the barrier and then the barrier shock into the acceptor, the pressure gradient behind the donor detonation wave, and the curvature of detonation front in the donor. Numerical simulations are used to illustrate how these factors affect the reaction in the acceptor.

Why do kids eat healthful food? Perceived benefits of and barriers to healthful eating and physical activity among children and adolescents.

Science.gov (United States)

O'dea, Jennifer A

2003-04-01

The goal was to have children and adolescents identify and rank the major perceived benefits of and barriers to healthful eating and physical activity and to suggest strategies for overcoming barriers. Semistructured, in-depth focus groups were undertaken using standardized questions and prompts. Students in grades 2 through 11(ages 7 through 17; N=213) from 34 randomly selected schools participated in 38 focus groups. Major benefits of healthful eating included improvements to cognitive and physical performance, fitness, endurance, psychological benefits, physical sensation (feeling good physically), and production of energy. Barriers included convenience, taste, and social factors. Benefits of physical activity included social benefits, enhancement of psychological status, physical sensation, and sports performance. Barriers included a preference for indoor activities, lack of energy and motivation, time constraints, and social factors. Suggested strategies for overcoming barriers included support from parents and school staff, better planning, time management, self-motivation, education, restructuring the physical environment, and greater variety of physical activities.

Impact of compliance with different guidelines on physical activity during pregnancy and perceived barriers to leisure physical activity.

Science.gov (United States)

Santos, Paula Clara; Abreu, Sandra; Moreira, Carla; Lopes, Diana; Santos, Rute; Alves, Odete; Silva, Pedro; Montenegro, Nuno; Mota, Jorge

2014-01-01

The aims of the this prospective study were to analyse physical activity (PA) engagement during the first and second trimesters, considering the different guidelines published on PA, to document the individual characteristics associated with the accomplishment of these guidelines and to examine pregnant women's perceived barriers to leisure PA, using a socioecological framework. A sample of 133 pregnant women in two stages--at 10-12 weeks' gestation (T1) and 20-22 weeks' gestation (T2)--were evaluated. PA was assessed by accelerometry during the T1 and T2 evaluation stages. Socio-demographic characteristics, lifestyle factors and barriers to leisure PA were assessed via questionnaire. A large proportion of women (ranging from 32% to 96%) did not reach the levels of PA recommended by the guidelines. There were no significant differences between T1 and T2 with regard to compliance with PA recommendations. A decrease in PA levels from T1 to T2 was noted for all recommendations. No associations were found between participants' characteristics and adherence to the recommendations in T1 and T2. No significant differences were found in barriers to leisure PA between T1 and T2. The most commonly reported barriers to leisure PA were intrapersonal, not health related. Our results indicate that there were no differences between trimesters regarding compliance of PA recommendations, and perceived barriers were similar in both trimesters.

Multiscale Treatment for the Molecular Mechanism of a Diels-Alder Reaction in Solution: A QM/MM-MD Study.

Science.gov (United States)

Soto-Delgado, Jorge; Tapia, Ricardo A; Torras, Juan

2016-10-11

Thermodynamics and the solvent role in the acceleration of the Diels-Alder reaction between cyclopentadiene (CPD) and methyl vinyl ketone (MVK) have been revisited. In this work we use an ab initio hybrid QM/MM-MD scheme combined with multiple steered molecular dynamics to extract the free energy pofile in water and methanol using the bidirectional Minh-Adib estimator. We obtain 18.7 kcal mol -1 and 20.8 kcal mol -1 free energy barrier for the reaction in water and methanol, respectively. This methodology reproduces experimental values with an absolute error of about 0.8 kcal mol -1 . The experimental difference between the activation free-energy barriers of water and methanol is also reproduced with an absolute error of about 0.1 kcal mol -1 . We explore the charge transfer evolution along reaction coordinates to characterize the electronic behavior for this reaction. It is shown that the solvent molecules around the reaction system produce a global polarization along the reaction coordinate which is consistent with the solvent polarity. The results highlight the role of hydrogen bonding formed in the transition state to stabilize the system charge reorganization in the reaction process.

Perceived Barriers to the Use of High-Fidelity Hands-On Simulation Training for Contrast Reaction Management: Why Programs are Not Using It.

Science.gov (United States)

Chinnugounder, Sankar; Hippe, Daniel S; Maximin, Suresh; O'Malley, Ryan B; Wang, Carolyn L

2015-01-01

Although subjective and objective benefits of high-fidelity simulation have been reported in medicine, there has been slow adoption in radiology. The purpose of our study was to identify the perceived barriers in the use of high-fidelity hands-on simulation for contrast reaction management training. An IRB exempt 32 questions online web survey was sent to 179 non-military radiology residency program directors listed in the Fellowship and Residency Electronic Interactive Database Access system (FREIDA). Survey questions included the type of contrast reaction management training, cost, time commitment of residents and faculty, and the reasons for not using simulation training. Responses from the survey were summarized as count (percentage), mean ± standard deviation (SD), or median (range). 84 (47%) of 179 programs responded, of which 88% offered CRM training. Most (72%) conducted the CRM training annually while only 4% conducted it more frequently. Didactic lecture was the most frequently used training modality (97%), followed by HFS (30%) and computer-based simulation (CBS) (19%); 5.5% used both HFS and CBS. Of the 51 programs that offer CRM training but do not use HFS, the most common reason reported was insufficient availability (41%). Other reported reasons included cost (33%), no access to simulation centers (33%), lack of trained faculty (27%) and time constraints (27%). Although high-fidelity hands-on simulation training is the best way to reproduce real-life contrast reaction scenarios, many institutions do not provide this training due to constraints such as cost, lack of access or insufficient availability of simulation labs, and lack of trained faculty. As a specialty, radiology needs to better address these barriers at both an institutional and national level. Copyright © 2015 Mosby, Inc. All rights reserved.

Full Kinetics from First Principles of the Chlorine Evolution Reaction over a RuO2 (110) Model Electrode.

Science.gov (United States)

Exner, Kai S; Anton, Josef; Jacob, Timo; Over, Herbert

2016-06-20

Current progress in modern electrocatalysis research is spurred by theory, frequently based on ab initio thermodynamics, where the stable reaction intermediates at the electrode surface are identified, while the actual energy barriers are ignored. This approach is popular in that a simple tool is available for searching for promising electrode materials. However, thermodynamics alone may be misleading to assess the catalytic activity of an electrochemical reaction as we exemplify with the chlorine evolution reaction (CER) over a RuO2 (110) model electrode. The full procedure is introduced, starting from the stable reaction intermediates, computing the energy barriers, and finally performing microkinetic simulations, all performed under the influence of the solvent and the electrode potential. Full kinetics from first-principles allows the rate-determining step in the CER to be identified and the experimentally observed change in the Tafel slope to be explained. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Perceived barriers to physical activity in older and younger veterans with serious mental illness.

Science.gov (United States)

Muralidharan, Anjana; Klingaman, Elizabeth A; Molinari, Victor; Goldberg, Richard W

2018-03-01

Individuals with serious mental illness endorse many more medical and psychosocial barriers to physical activity (PA) than the general population. However, it is unknown if older adults with serious mental illness are at greater risk of experiencing barriers to PA than their younger counterparts. The present study utilized a national VA dataset to compare veterans with serious mental illness ages 55 and older (n = 9,044) to veterans with serious mental illness ages 54 and younger (n = 8,782) on their responses to a questionnaire assessment of barriers to PA. Older veterans were more likely to endorse arthritis and cardiopulmonary disease, and less likely to endorse work schedule, as barriers to PA. Interventions designed to increase PA for young/middle-aged adults with serious mental illness may be broadly useful for older adults with serious mental illness, with some modification to address specific health concerns. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Reaction rate of propene pyrolysis.

Science.gov (United States)

Han, Peipei; Su, Kehe; Liu, Yan; Wang, Yanli; Wang, Xin; Zeng, Qingfeng; Cheng, Laifei; Zhang, Litong

2011-10-01

The reaction rate of propene pyrolysis was investigated based on the elementary reactions proposed in Qu et al., J Comput Chem 2009, 31, 1421. The overall reaction rate was developed with the steady-state approximation and the rate constants of the elementary reactions were determined with the variational transition state theory. For the elementary reaction having transition state, the vibrational frequencies of the selected points along the minimum energy path were calculated with density functional theory at B3PW91/6-311G(d,p) level and the energies were improved with the accurate model chemistry method G3(MP2). For the elementary reaction without transition state, the frequencies were calculated with CASSCF/6-311G(d,p) and the energies were refined with the multireference configuration interaction method MRCISD/6-311G(d,p). The rate constants were evaluated within 200-2000 K and the fitted three-parameter expressions were obtained. The results are consistent with those in the literatures in most cases. For the overall rate, it was found that the logarithm of the rate and the reciprocal temperature have excellent linear relationship above 400 K, predicting that the rate follows a typical first-order law at high temperatures of 800-2000 K, which is also consistent with the experiments. The apparent activation energy in 800-2000 K is 317.3 kJ/mol from the potential energy surface of zero Kelvin. This value is comparable with the energy barriers, 365.4 and 403.7 kJ/mol, of the rate control steps. However, the apparent activation energy, 215.7 kJ/mol, developed with the Gibbs free energy surface at 1200 K is consistent with the most recent experimental result 201.9 ± 0.6 kJ/mol. Copyright © 2011 Wiley Periodicals, Inc.

Thermal activation of dislocations in large scale obstacle bypass

Science.gov (United States)

Sobie, Cameron; Capolungo, Laurent; McDowell, David L.; Martinez, Enrique

2017-08-01

Dislocation dynamics simulations have been used extensively to predict hardening caused by dislocation-obstacle interactions, including irradiation defect hardening in the athermal case. Incorporating the role of thermal energy on these interactions is possible with a framework provided by harmonic transition state theory (HTST) enabling direct access to thermally activated reaction rates using the Arrhenius equation, including rates of dislocation-obstacle bypass processes. Moving beyond unit dislocation-defect reactions to a representative environment containing a large number of defects requires coarse-graining the activation energy barriers of a population of obstacles into an effective energy barrier that accurately represents the large scale collective process. The work presented here investigates the relationship between unit dislocation-defect bypass processes and the distribution of activation energy barriers calculated for ensemble bypass processes. A significant difference between these cases is observed, which is attributed to the inherent cooperative nature of dislocation bypass processes. In addition to the dislocation-defect interaction, the morphology of the dislocation segments pinned to the defects play an important role on the activation energies for bypass. A phenomenological model for activation energy stress dependence is shown to describe well the effect of a distribution of activation energies, and a probabilistic activation energy model incorporating the stress distribution in a material is presented.

Facilitators and Barriers to Performing Activities and Participation in Children With Cerebral Palsy: Caregivers' Perspective.

Science.gov (United States)

Earde, Pinailug Tantilipikorn; Praipruk, Aina; Rodpradit, Phanlerd; Seanjumla, Parichad

2018-01-01

To investigate contextual factors that were facilitators and barriers to performing activity and participation for children with cerebral palsy from the caregivers' perspective. Qualitative in-depth interview with primary caregivers of children with cerebral palsy aged 4 to 12 years was conducted in the metropolitan area of Thailand. Semistructured questions related to environmental and personal factors were recorded. Interviews were transcribed verbatim and analyzed for main themes on the basis of the International Classification of Functioning, Disability, and Health-Children and Youth Version (ICF-CY) classification. Twenty-seven caregivers participated. Facilitators were appropriateness of assistive devices, support and acceptance from family, friends, and society, health services, willingness, and self-acceptance. Barriers were inappropriate design and facilities, overprotection of family, nonacceptance from family, friends, and society, inconvenient transportation, financial problems, limited health services, limited access to education, frustration, and being an introvert. Contextual factors that can be facilitators and barriers to perform activities and participation should be considered for improving lives of children with cerebral palsy.

Study of the angular momentum distribution of compound nuclei obtained from fusion reactions close to the Coulomb barrier

International Nuclear Information System (INIS)

Romain, P.

1990-03-01

The effect of the mass asymmetry of the input channel on the compound nuclei spin distribution. The 16 O + 144 Nd and 80 Se + 80 Se reactions produce the same 160 Er compound nucleus in the 38 to 68 MeV energy range. In certain cases, the incident energies required to form the compound nucleus, at the same excitation energies, are very close to the Coulomb barrier. In the experimental device, the 'Chateau de Cristal' multidetector and additional sensors are used. The angular momentum distribution of the different evaporation products are measured by gamma spectrometry techniques. The fusion cross sections are measured by the time-of-flight technique. Theoretical predictions and experimental results concerning the distribution of the compound nucleus angular momentum are compared [fr

Investigation of Thermochemistry Associated with the Carbon–Carbon Coupling Reactions of Furan and Furfural Using ab Initio Methods

Energy Technology Data Exchange (ETDEWEB)

Liu, Cong; Assary, Rajeev S.; Curtiss, Larry A.

2014-06-26

Upgrading of furan and small oxygenates obtained from the decomposition of cellulosic materials via formation of carbon-carbon bonds is critical to effective conversion of biomass to liquid transportation fuels. Simulation-driven molecular level understanding of carbon-carbon bond formation is required to design efficient catalysts and processes. Accurate quantum chemical methods are utilized here to predict the reaction energetics for conversion of furan (C4H4O) to C5-C8 ethers and the transformation of furfural (C5H6O2) to C13-C26 alkanes. Furan, can be coupled with various C1 to C4 lower molecular weight carbohydrates obtained from the pyrolysis via Diels-Alder type reactions in the gas phase to produce C5-C8 cyclic ethers. The computed reaction barriers for these reactions (~25 kcal/mol) are lower than the cellulose activation or decomposition reactions (~50 kcal/mol). Cycloaddition of C5-C8 cyclo-ethers with furans can also occur in the gas phase, and the computed activation energy is similar to that of the first Diels-Alder reaction. Furfural, obtained from biomass, can be coupled with aldehydes or ketones with α-hydrogen atoms to form longer chain aldol products and these aldol products can undergo vapor phase hydrocycloaddition (activation barrier of ~20 kcal/mol) to form the precursors of C26 cyclic hydrocarbons. These thermochemical studies provide the basis for further vapor phase catalytic studies required for upgrading of furans/furfurals to longer chain hydrocarbons.

Knowledge, perception, practices and barriers of healthcare professionals in Bosnia and Herzegovina towards adverse drug reaction reporting and pharmacovigilance

Directory of Open Access Journals (Sweden)

Maša Amrain

2014-09-01

Full Text Available Introduction: Pharmacovigilance is an arm of patient care. No one wants to harm patients, but unfortunately any medicine will sometimes do just this. Underreporting of adverse drug reactions by healthcare professionals is a major problem in many countries. In order to determine whether our pharmacovigilance system could be improved, and identify reasons for under-reporting, a study to investigate the role of health care professionals in adverse drug reaction (ADR reporting was performed.Methods: A pretested questionnaire comprising of 20 questions was designed for assessment of knowledge, perceptions, practice and barriers toward ADR reporting on a random sample of 1000 healthcare professionals in Bosnia and Herzegovina.Results: Of the 1000 respondents, 870 (87% completed the questionnaire. The survey showed that 62.9% health care professionals would report ADR to the Agency for Medicinal Products and Medical Device of Bosnia and Herzegovina (ALMBIH. Most of surveyed respondents has a positive perception towards ADR reporting, and believes that this is part of their professional and legal obligation, and they also recognize the importance of reporting adverse drug reactions. Only small percent (15.4% of surveyed health care professionals reported adverse drug reaction.Conclusions: The knowledge of ADRs and how to report them is inadequate among health care professionals. Perception toward ADR reporting was positive, but it is not reflected in the actual practice of ADRs, probably because of little experience and knowledge regarding pharmacovigilance. Interventions such as education and training, focusing on the aims of pharmacovigilance, completing the ADR form and clarifying the reporting criteria are strongly recommended.

Physical activity in patients with heart failure: barriers and motivations with special focus on sex differences

Directory of Open Access Journals (Sweden)

Klompstra L

2015-11-01

Full Text Available Leonie Klompstra,1 Tiny Jaarsma,1 Anna Strömberg2,31Department of Social and Welfare Studies, Faculty of Health Sciences, 2Department of Medical and Health Sciences, Division of Nursing, 3Department of Cardiology, Linköping University, Linköping, SwedenBackground: Adherence to recommendations for physical activity is low in both male and female patients with heart failure (HF. Men are more physically active than women. In order to successfully promote physical activity, it is therefore essential to explore how much and why HF patients are physically active and if this is related to sex. The aim of this study was therefore to evaluate physical activity in HF patients, to describe the factors related to physical activity, and to examine potential barriers and motivations to physical activity with special focus on sex differences.Methods: The study had a cross-sectional survey design. HF patients living at home received a questionnaire during May–July 2014, with questions on physical activity (from the Short Form-International Physical Activity Questionnaire, and potential barriers and motivations to physical activity.Results: A total of 154 HF patients, 27% women, with a mean age of 70±10 were included. In total, 23% of the patients reported a high level of physical activity, 46% a moderate level, and 34% a low level. Higher education, self-efficacy, and motivation were significantly associated with a higher amount of physical activity. Symptoms or severity of the disease were not related to physical activity. All the potential barriers to exercise were reported to be of importance. Psychological motivations were most frequently rated as being the most important motivation (41% to be physically active. Physical motivations (33% and social motivations were rated as the least important ones (22%. Women had significantly higher total motivation to be physically active. These differences were found in social, physical, and psychological

Mechanism of Cytochrome P450 17A1-Catalyzed Hydroxylase and Lyase Reactions

DEFF Research Database (Denmark)

Bonomo, Silvia; Jorgensen, Flemming Steen; Olsen, Lars

2017-01-01

Cytochrome P450 17A1 (CYP17A1) catalyzes C17 hydroxylation of pregnenolone and progesterone and the subsequent C17–C20 bond cleavage (lyase reaction) to form androgen precursors. Compound I (Cpd I) and peroxo anion (POA) are the heme-reactive species underlying the two reactions. We have characte...... the concept that the selectivity of the steroidogenic CYPs is ruled by direct interactions with the enzyme, in contrast to the selectivity of drug-metabolizing CYPs, where the reactivity of the substrates dominates....... characterized the reaction path for both the hydroxylase and lyase reactions using density functional theory (DFT) calculations and the enzyme–substrate interactions by molecular dynamics (MD) simulations. Activation barriers for positions subject to hydroxylase reaction have values close to each other and span...

Predictors of physical activity and barriers to exercise in nursing and medical students

OpenAIRE

Blake, Holly; Stanulewicz, Natalia; McGill, Francesca

2016-01-01

Aims\\ud \\ud To investigate physical activity levels of nursing and medicine students; examine predictors of physical activity level; and examine the most influential benefits and barriers to exercise.\\ud Background\\ud \\ud Healthcare professionals have low levels of physical activity, which increases their health risk and may influence their health promotion practices with patients.\\ud Design\\ud \\ud We surveyed 361 nursing (n=193) and medicine (n=168) students studying at a UK medical school.\\...

Some insights into formamide formation through gas-phase reactions in the interstellar medium

International Nuclear Information System (INIS)

Redondo, Pilar; Barrientos, Carmen; Largo, Antonio

2014-01-01

We study the viability of different gas-phase ion-molecule reactions that could produce precursors of formamide in the interstellar medium. We analyze different reactions between cations containing a nitrogen atom (NH 3 + , NH 4 + , NH 3 OH + , and NH 2 OH + ) and neutral molecules having one carbonyl group (H 2 CO and HCOOH). First, we report a theoretical estimation of the reaction enthalpies for the proposed processes. Second, for more favorable reactions, from a thermodynamic point of view, we perform a theoretical study of the potential energy surface. In particular, the more exothermic processes correspond to the reactions of ionized and protonated hydroxylamine with formaldehyde. In addition, a neutral-neutral reaction has also been considered. The analysis of the potential energy surfaces corresponding to these reactions shows that these processes present a net activation barrier and that they cannot be considered as a source of formamide in space.

Some Insights into Formamide Formation through Gas-phase Reactions in the Interstellar Medium

Science.gov (United States)

Redondo, Pilar; Barrientos, Carmen; Largo, Antonio

2014-01-01

We study the viability of different gas-phase ion-molecule reactions that could produce precursors of formamide in the interstellar medium. We analyze different reactions between cations containing a nitrogen atom (NH_{3}^{+}, NH_{4}^{+}, NH3OH+, and NH2OH+) and neutral molecules having one carbonyl group (H2CO and HCOOH). First, we report a theoretical estimation of the reaction enthalpies for the proposed processes. Second, for more favorable reactions, from a thermodynamic point of view, we perform a theoretical study of the potential energy surface. In particular, the more exothermic processes correspond to the reactions of ionized and protonated hydroxylamine with formaldehyde. In addition, a neutral-neutral reaction has also been considered. The analysis of the potential energy surfaces corresponding to these reactions shows that these processes present a net activation barrier and that they cannot be considered as a source of formamide in space.

Physical activity practice among children and adolescents with visual impairment--influence of parental support and perceived barriers.

Science.gov (United States)

Greguol, Márcia; Gobbi, Erica; Carraro, Attilio

2015-01-01

To analyze the practice of physical activity among children and adolescents with visual impairments (VI), regarding the possible influence of parental support and perceived barriers. Twenty-two young people with VIs (10 + 2.74 years old) and one of each of their parents were evaluated. They responded to the Physical Activity Questionnaire for Older Children (PAQ-C), Baecke Questionnaire, the Parental Support Scale and a questionnaire about perceived barriers to physical activity. The independent samples t-test, pearson correlation test and chi-square test were performed. Blind young people showed lower physical activity levels. There were significant correlations both between parents' physical activity and the support offered to children and between the PAQ-C results and the importance given by young people to physical activity, but only for those aged between 8 and 10 years old. The main perceived barriers were lack of security, motivation, professional training and information about available physical activity programs. The influence of parental support seems to be an important factor in the adoption of a physically active lifestyle for young people with VI. Parents and children should have more information about the benefits and opportunities of physical activity. Implications for Rehabilitation Young people with visual impairment should be encouraged by parents to practice physical activity. More information should be provided on the benefits of physical activity to both parents and children. Professional training should be available to help support this group become more active.

Ground reaction forces, kinematics, and muscle activations during the windmill softball pitch.

Science.gov (United States)

Oliver, Gretchen D; Plummer, Hillary

2011-07-01

The aims of the present study were to examine quantitatively ground reaction forces, kinematics, and muscle activations during the windmill softball pitch, and to determine relationships between knee valgus and muscle activations, ball velocity and muscle activation as well as ball velocity and ground reaction forces. It was hypothesized that there would be an inverse relationship between degree of knee valgus and muscle activation, a direct relationship between ground reaction forces and ball velocity, and non-stride leg muscle activations and ball velocity. Ten female windmill softball pitchers (age 17.6 ± 3.47 years, stature 1.67 ± 0.07 m, weight 67.4 ± 12.2 kg) participated. Dependent variables were ball velocity, surface electromyographic (sEMG), kinematic, and kinetic data while the participant was the independent variable. Stride foot contact reported peak vertical forces of 179% body weight. There were positive relationships between ball velocity and ground reaction force (r = 0.758, n = 10, P = 0.029) as well as ball velocity and non-stride leg gluteus maximus (r = 0.851, n = 10, P = 0.007) and medius (r = 0.760, n = 10, P = 0.029) muscle activity, while there was no notable relationship between knee valgus and muscle activation. As the windmill softball pitcher increased ball velocity, her vertical ground reaction forces also increased. Proper conditioning of the lumbopelvic-hip complex, including the gluteals, is essential for injury prevention. From the data presented, it is evident that bilateral strength and conditioning of the gluteal muscle group is salient in the windmill softball pitch as an attempt to decrease incidence of injury.

Proliferative activity as a prognostic factor of a human tumor radiation reactions

International Nuclear Information System (INIS)

Karakulov, R.K.; Pelevina, I.I.

1986-01-01

The following questions are considered: 1) whether cell proliferation initial parameters can serve for predicting the tumor radial reaction; 2) whether proliferative activity change can be a criterion for estimating the treatment efficiency; 3) acquisition of data on biological peculiarities of different types of tumors. Connection between proliferative activity drop and clinical reaction under tumor radiotherapy is ascertained

Mechanism of the Suzuki–Miyaura Cross-Coupling Reaction Mediated by [Pd(NHC)(allyl)Cl] Precatalysts

KAUST Repository

Meconi, Giulia Magi

2017-05-24

Density functional theory calculations have been used to investigate the activation mechanism for the precatalyst series [Pd]-X-1–4 derived from [Pd(IPr)(R-allyl)X] species by substitutions at the terminal position of the allyl moiety ([Pd] = Pd(IPr); R = H (1), Me (2), gem-Me2 (3), Ph (4), X = Cl, Br). Next, we have investigated the Suzuki–Miyaura cross-coupling reaction for the active catalyst species IPr-Pd(0) using 4-chlorotoluene and phenylboronic acid as substrates and isopropyl alcohol as a solvent. Our theoretical findings predict an upper barrier trend, corresponding to the activation mechanism for the [Pd]-Cl-1–4 series, in good agreement with the experiments. They indeed provide a quantitative explanation of the low yield (12%) displayed by [Pd]-Cl-1 species (ΔG⧧ ≈ 30.0 kcal/mol) and of the high yields (≈90%) observed in the case of [Pd]-Cl-2–4 complexes (ΔG⧧ ≈ 20.0 kcal/mol). Additionally, the studied Suzuki–Miyaura reaction involving the IPr-Pd(0) species is calculated to be thermodynamically favorable and kinetically facile. Similar investigations for the [Pd]-Br-1–4 series, derived from [Pd(IPr)(R-allyl)Br], indicate that the oxidative addition step for IPr-Pd(0)-mediated catalysis with 4-bromotoluene is kinetically more favored than that with 4-chlorotoluene. Finally, we have explored the potential of Ni-based complexes [Ni((IPr)(R-allyl)X] (X = Cl, Br) as Suzuki–Miyaura reaction catalysts. Apart from a less endergonic reaction energy profile for both precatalyst activation and catalytic cycle, a steep increase in the predicted upper energy barriers (by 2.0–15.0 kcal/mol) is calculated in the activation mechanism for the [Ni]-X-1–4 series compared to the [Pd]-X-1–4 series. Overall, these results suggest that Ni-based precatalysts are expected to be less active than the Pd-based precatalysts for the studied Suzuki–Miyaura reaction.

Nuclear structure and fusion at the barrier

International Nuclear Information System (INIS)

Reisdorf, W.

1985-01-01

A comparative study of measured fusion excitation functions in the vicinity of the barrier reveals nuclear structure effects, due in particular to the coupling of the fusion process to direct-reaction channels. (orig.)

Study on fusion potential barrier in heavy ion reactions based on the dynamical model

International Nuclear Information System (INIS)

Tian Junlong; Wu Xizhen; Li Zhuxia; Wang Ning; Liu Fuhu

2004-01-01

Based on an improved quantum molecular dynamics model the static and dynamic potential in the entrance channel of synthesis of superheavy nuclei are studied. The dependence of the static potential (and driving potential) on mass-asymmetry is obtained. From this study authors find out that the mass-symmetric system seems to be difficult to fuse and the fusing system with the largest driving potential could be the optimal choice of the projectile-target combination. By comparing the static potential barrier with the dynamic one authors find that the latter one is lower than former one obviously, and that the dynamical potential barrier is entrance energy dependent. The maximum and minimum of dynamic potential barriers approach to the diabatic (sudden approximation) and the adiabatic static potential barriers, respectively

Confronting Physical Activity Programming Barriers for People with Disabilities: The Empowerment Model

Science.gov (United States)

Moran, Thomas Eugene; Taliaferro, Andrea R.; Pate, Joshua R.

2014-01-01

Community-based physical activity programs for people with disabilities have barriers that are unique to their program leader qualifications and the population they serve. Moran and Block (2010) argued that there is a need for practical strategies that are easy for communities to implement, maximize resources, and minimize the impact of barriers…

Theoretical studies of mechanisms of cycloaddition reaction between difluoromethylene carbene and acetone

Science.gov (United States)

Lu, Xiu Hui; Yu, Hai Bin; Wu, Wei Rong; Xu, Yue Hua

Mechanisms of the cycloaddition reaction between singlet difluoromethylene carbene and acetone have been investigated with the second-order Møller-Plesset (MP2)/6-31G* method, including geometry optimization and vibrational analysis. Energies for the involved stationary points on the potential energy surface (PES) are corrected by zero-point energy (ZPE) and CCSD(T)/6-31G* single-point calculations. From the PES obtained with the CCSD(T)//MP2/6-31G* method for the cycloaddition reaction between singlet difluoromethylene carbene and acetone, it can be predicted that path B of reactions 2 and 3 should be two competitive leading channels of the cycloaddition reaction between difluoromethylene carbene and acetone. The former consists of two steps: (i) the two reactants first form a four-membered ring intermediate, INT2, which is a barrier-free exothermic reaction of 97.8 kJ/mol; (ii) the intermediate INT2 isomerizes to a four-membered product P2b via a transition state TS2b with an energy barrier of 24.9 kJ/mol, which results from the methyl group transfer. The latter proceeds in three steps: (i) the two reactants first form an intermediate, INT1c, through a barrier-free exothermic reaction of 199.4 kJ/mol; (ii) the intermediate INT1c further reacts with acetone to form a polycyclic intermediate, INT3, which is also a barrier-free exothermic reaction of 27.4 kJ/mol; and (iii) INT3 isomerizes to a polycyclic product P3 via a transition state TS3 with an energy barrier of 25.8 kJ/mol.

Barriers to meditation by gender and age among cancer family caregivers.

Science.gov (United States)

Williams, Anna-Leila; Ness, Peter Van; Dixon, Jane; McCorkle, Ruth

2012-01-01

Despite solid basic science research supporting meditation's physiologic benefits, meditation remains a marginalized practice for many Westerners; observational and descriptive studies indicate a spectrum of barriers to meditation practice. The aim of this study was to determine differences in barriers to meditation by gender and age. A cross-sectional survey study of 150 family caregivers to adults with cancer visiting an outpatient chemotherapy center in Connecticut was conducted. The primary outcome was the Determinants of Meditation Practice Inventory. Explanatory variables included demographic characteristics, Center for Epidemiologic Studies-Depression Scale, Big Five Inventory, and Caregiver Reaction Assessment. Participants included 98 women and 52 men. Age range was 18-84 years (M = 52.3 years). The highest frequency of barriers for both genders related to misconceptions about meditation. The total number of barriers to meditation did not significantly vary by gender (p = .10) nor age (p = .27). After adjusting for personality trait, reactions to caregiving, and emotional distress, gender (adjusted β = 0.81, SE = 1.70, p = .63) and age (adjusted β = 0.02, SE = 0.05, p = .67) still did not predict the number of barriers to meditation. Backward elimination in model building showed that personality trait and reactions to caregiving account for 32% of the variability in barriers. The total number of barriers to meditation was examined, and a difference was not found by age or gender. It is possible that differences by age and gender exist at the item level of evaluation but were not evident when evaluating total scores. Further study is needed with samples large enough to have statistical power for item-level analysis.

Atopic dermatitis: immune deviation, barrier dysfunction, IgE autoreactivity and new therapies

Directory of Open Access Journals (Sweden)

Masutaka Furue

2017-07-01

Full Text Available Atopic dermatitis (AD is a chronic or chronically relapsing, eczematous, severely pruritic skin disorder mostly associated with IgE elevation and skin barrier dysfunction due to decreased filaggrin expression. The lesional skin of AD exhibits Th2- and Th22-deviated immune reactions that are progressive during disease chronicity. Th2 and Th22 cytokines further deteriorate the skin barrier by inhibiting filaggrin expression. Some IgEs are reactive to self-antigens. The IgE autoreactivity may precipitate the chronicity of AD. Upon activation of the ORAI1 calcium channel, atopic epidermis releases large amounts of thymic stromal lymphopoietin (TSLP, which initiates the Th2 and Th22 immune response. Th2-derived interleukin-31 and TSLP induce an itch sensation. Taken together, TSLP/Th2/Th22 pathway is a promising target for developing new therapeutics for AD. Enhancing filaggrin expression using ligands for the aryl hydrocarbon receptor may also be an adjunctive measure to restore the disrupted barrier function specifically for AD.

Unimolecular reaction dynamics of free radicals

International Nuclear Information System (INIS)

Terry A. Miller

2006-01-01

Free radical reactions are of crucial importance in combustion and in atmospheric chemistry. Reliable theoretical models for predicting the rates and products of these reactions are required for modeling combustion and atmospheric chemistry systems. Unimolecular reactions frequently play a crucial role in determining final products. The dissociations of vinyl, CH2= CH, and methoxy, CH3O, have low barriers, about 13,000 cm-1 and 8,000 cm-1, respectively. Since barriers of this magnitude are typical of free radicals these molecules should serve as benchmarks for this important class of reactions. To achieve this goal, a detailed understanding of the vinyl and methoxy radicals is required. Results for dissociation dynamics of vinyl and selectively deuterated vinyl radical are reported. Significantly, H-atom scrambling is shown not to occur in this reaction. A large number of spectroscopic experiments for CH3O and CHD2O have been performed. Spectra recorded include laser induced fluorescence (LIF), laser excited dispersed fluorescence (LEDF), fluorescence dip infrared (FDIR) and stimulated emission pumping (SEP). Such results are critical for implementing dynamics experiments involving the dissociation of methoxy

An Activity Theory Approach to Analyze Barriers to a Virtual Management Information Systems (MIS) Curriculum

Science.gov (United States)

Jaradat, Suhair; Qablan, Ahmad; Barham, Areej

2011-01-01

This paper explains how the activity theory is used as a framework to analyze the barriers to a virtual Management Information Stream (MIS) Curriculum in Jordanian schools, from both the sociocultural and pedagogical perspectives. Taking the activity system as a unit of analysis, this study documents the processes by which activities shape and are…

Beliefs, Barriers and Facilitators to Physical Activity in Bariatric Surgery Candidates.

Science.gov (United States)

Zabatiero, Juliana; Hill, Kylie; Gucciardi, Daniel F; Hamdorf, Jeffrey M; Taylor, Susan F; Hagger, Martin S; Smith, Anne

2016-05-01

Bariatric surgery candidates engage in less physical activity (PA) and spend longer periods in sedentary behaviour (SB) when compared to the general adult population. The aim of this study was to explore the beliefs about PA and perceived barriers and facilitators to PA in obese adults scheduled for bariatric surgery. Nineteen obese adults (15 females), with a mean (SD) age of 41.6 (12.1) years, weight of 119.2 (20.5) kg and body mass index of 41.6 (6.7) kg/m(2) participated in a one-on-one in-depth qualitative interview before undergoing bariatric surgery. Data were analysed using inductive thematic analysis. Most participants believed that engaging in regular PA confers important health benefits, however reported insufficient PA levels to obtain those benefits. The perceived barriers to PA reported by participants were both obesity related (e.g. bodily pain, physical limitation and self-presentational concerns) and non-obesity related (e.g. lack of motivation, environment and restricted resources). All participants stated weight loss to be the main perceived facilitator to PA, together with social factors, better time management and access to financial resources. In bariatric surgery candidates, many of the perceived barriers and facilitators to PA are not obesity related and are therefore unlikely to change as a result of bariatric surgery. This may explain why earlier research shows little change in PA or SB following surgery. It is likely that an approach that aims to address the barriers and facilitators identified in this study is needed to change the inactive lifestyle adopted in this population.

Recombination barrier layers in solid-state quantum dot-sensitized solar cells

KAUST Repository

Roelofs, Katherine E.; Brennan, Thomas P.; Dominguez, Juan C.; Bent, Stacey F.

2012-01-01

in situ by successive ion layer adsorption and reaction (SILAR). Aluminum oxide recombination barrier layers were deposited by atomic layer deposition (ALD) at the TiO2/hole-conductor interface. For low numbers of ALD cycles, the Al2O3 barrier layer

Polyphenol-Rich Propolis Extracts Strengthen Intestinal Barrier Function by Activating AMPK and ERK Signaling

Directory of Open Access Journals (Sweden)

Kai Wang

2016-05-01

Full Text Available Propolis has abundant polyphenolic constituents and is used widely as a health/functional food. Here, we investigated the effects of polyphenol-rich propolis extracts (PPE on intestinal barrier function in human intestinal epithelial Caco-2 cells, as well as in rats. In Caco-2 cells, PPE increased transepithelial electrical resistance and decreased lucifer yellow flux. PPE-treated cells showed increased expression of the tight junction (TJ loci occludin and zona occludens (ZO-1. Confocal microscopy showed organized expressions in proteins related to TJ assembly, i.e., occludin and ZO-1, in response to PPE. Furthermore, PPE led to the activation of AMPK, ERK1/2, p38, and Akt. Using selective inhibitors, we found that the positive effects of PPE on barrier function were abolished in cells in which AMPK and ERK1/2 signaling were inhibited. Moreover, rats fed a diet supplemented with PPE (0.3% in the diet exhibited increased colonic epithelium ZO-1 expression. Overall, these data suggest that PPE strengthens intestinal barrier function by activating AMPK and ERK signaling and provide novel insights into the potential application of propolis for human gut health.

Statistical analysis of activation and reaction energies with quasi-variational coupled-cluster theory

Science.gov (United States)

Black, Joshua A.; Knowles, Peter J.

2018-06-01

The performance of quasi-variational coupled-cluster (QV) theory applied to the calculation of activation and reaction energies has been investigated. A statistical analysis of results obtained for six different sets of reactions has been carried out, and the results have been compared to those from standard single-reference methods. In general, the QV methods lead to increased activation energies and larger absolute reaction energies compared to those obtained with traditional coupled-cluster theory.

Non-Critical-Care Nurses' Perceptions of Facilitators and Barriers to Rapid Response Team Activation.

Science.gov (United States)

Jenkins, Sheryl Henry; Astroth, Kim Schafer; Woith, Wendy Mann

2015-01-01

Rapid response teams can save lives but are only effective when activated. We surveyed 50 nurses for their perceptions of facilitators and barriers to activation. Findings showed that participants need more education on their role and when to activate the rapid response team. Nurses who comprise the team need help building their communication skills. We recommend nursing professional development specialists increase the frequency of offerings and expand the focus on roles, activation criteria, and communication skills.

Analysis by nuclear reactions and activations. A current bibliography

International Nuclear Information System (INIS)

Bujdoso, E.

2001-01-01

A current bibliography based on INIS Atomindex with 78 references on Analysis by nuclear reactions and activations has been prepared for year 1998. References are arranged by first authors' name. (N.T.)

Self-activated, self-limiting reactions on Si surfaces

DEFF Research Database (Denmark)

Morgen, Per; Hvam, Jeanette; Bahari, Ali

The direct thermally activated reactions of oxygen and ammonia with Si surfaces in furnaces have been used for a very long time in the semiconductor industry for the growth of thick oxides and nitride layers respectively. The oxidation mechanism was described in the Deal-Grove model as a diffusion...... mechanism for the direct growth of ultrathin films (0-3 nm) of oxides and nitrides under ultrahigh vacuum conditions. Neutral oxygen and a microwave excited nitrogen plasma interact directly with Si surfaces kept at different temperatures during the reaction. The gas pressures are around 10-6 Torr...... energy of an oxide system, which happened for an ordered structure, at a thickness of 0.7-0.8 nm. Thus this thin oxide structure has definite crystalline features. We have closely monitored the reaction kinetics with normal x-ray induced photoelectron spectroscopies, and also the structure, composition...

Physical activity perceptions, context, barriers, and facilitators from a Hispanic child's perspective

Science.gov (United States)

Ross, Sharon E. Taverno; Francis, Lori A.

2016-01-01

Background In order to develop effective physical activity interventions and to address the burden of obesity in Hispanic children, qualitative studies are needed to build descriptive theory and expand the state of the science. The purpose of this study is to describe physical activity perceptions, context, facilitators, and barriers from the perspective of Hispanic immigrant-origin children. Method This in-depth, ethnographic study included 14, 6- to 11-year old, first- and second- generation Hispanic children recruited from an afterschool program in Southeastern Pennsylvania, USA. Methods included child observation, field notes, semi-structured interviews, and a PhotoVoice activity. Transcripts and field notes were coded and analyzed using the constant comparison method to identify overarching themes and patterns in the data. Results Data analysis yielded four overarching themes regarding children's perspectives on physical activity. Children engaged in a variety of physical activities and sedentary behaviors, which differed by physical (e.g., park, outside home, and afterschool programs) and social (e.g., parents, siblings, and friends) contexts. Children discussed specific benefits of physical activity. Children's negative attitudes toward physical activity were related to physical discomfort, low athletic competence, and safety concerns. Children perceived physical activity and play to be one in the same, and “fun” was identified as a primary driver of physical activity preferences. The facilitators and barriers to physical activity were related to specific parent/home, school, and neighborhood factors. Conclusion Findings from this study suggest that an emphasis on fun and active play, while taking into account family and neighborhood context, may be a desirable intervention approach in Hispanic immigrant-origin children. This study lays the groundwork for future studies to further explore some of the themes identified here to better understand children

Physical activity perceptions, context, barriers, and facilitators from a Hispanic child's perspective

Directory of Open Access Journals (Sweden)

Sharon E. Taverno Ross

2016-08-01

Full Text Available Background: In order to develop effective physical activity interventions and to address the burden of obesity in Hispanic children, qualitative studies are needed to build descriptive theory and expand the state of the science. The purpose of this study is to describe physical activity perceptions, context, facilitators, and barriers from the perspective of Hispanic immigrant-origin children. Method: This in-depth, ethnographic study included 14, 6- to 11-year old, first- and second- generation Hispanic children recruited from an afterschool program in Southeastern Pennsylvania, USA. Methods included child observation, field notes, semi-structured interviews, and a PhotoVoice activity. Transcripts and field notes were coded and analyzed using the constant comparison method to identify overarching themes and patterns in the data. Results: Data analysis yielded four overarching themes regarding children's perspectives on physical activity. Children engaged in a variety of physical activities and sedentary behaviors, which differed by physical (e.g., park, outside home, and afterschool programs and social (e.g., parents, siblings, and friends contexts. Children discussed specific benefits of physical activity. Children's negative attitudes toward physical activity were related to physical discomfort, low athletic competence, and safety concerns. Children perceived physical activity and play to be one in the same, and “fun” was identified as a primary driver of physical activity preferences. The facilitators and barriers to physical activity were related to specific parent/home, school, and neighborhood factors. Conclusion: Findings from this study suggest that an emphasis on fun and active play, while taking into account family and neighborhood context, may be a desirable intervention approach in Hispanic immigrant-origin children. This study lays the groundwork for future studies to further explore some of the themes identified here to better

Motivations and barriers to prosthesis users participation in physical activity, exercise and sport: a review of the literature.

Science.gov (United States)

Deans, Sarah; Burns, David; McGarry, Anthony; Murray, Kevin; Mutrie, Nanette

2012-09-01

The UK will host the Paralympics in 2012 and the Commonwealth Games in 2014 showcasing the talents of elite athletes and aiming to inspire the population to become involved. However, low levels of physical activity are prevalent: only 40% of men and 28% of women meet the minimum UK physical activity recommendations. The population of people with limb absence is no exception. To determine if people with amputation are participating in physical activity and sport; whether post-amputation activity levels match pre-amputation levels; and if there are motivations and barriers to participation. Literature review. Five reviewers systematically searched all peer reviewed and gray literature in seven bibliographic databases and the Cochrane Library. Following rigorous elimination, 12 articles were finally included in the review and critically appraised. Four themes were identified: components; rehabilitation outcomes; body image; and motivations and barriers to participation. People with limb absence are not participating in physical activity conducive to health benefits, and only a minority participate in exercise and sports. Participation following amputation does not mirror that of pre-amputation levels, and more barriers than motivations exist to adopting or maintaining a physically active lifestyle.

Influence of refreshment/activation cycles and temperature rise on the reaction rate of sodium hypochlorite with bovine dentine during ultrasonic activated irrigation.

Science.gov (United States)

Macedo, R G; Verhaagen, B; Wesselink, P R; Versluis, M; van der Sluis, L W M

2014-02-01

To evaluate the effect of multiple refreshment/activation cycles and temperature on the reaction rate of sodium hypochlorite (NaOCl) with bovine dentine during ultrasonic activated irrigation (UAI) under laboratory conditions. The root canal walls of 24 standardized root canals in bovine incisors were exposed to a standardized volume of NaOCl at different temperatures (24 °C and 38 °C) and exposure times (20, 60 and 180 s). The irrigant was refreshed and ultrasonically activated four times for 20 s followed by a 40 s rest interval, with no refreshment and no activation as the controls. The reaction rate was determined by measuring the amount of active chlorine in the NaOCl solution before and after being exposed to dentine during the specific experimental conditions. Calorimetry was used to measure the electrical-to-sonochemical conversion efficiency during ultrasonic activation. Refreshment, activation and exposure time all increased the reaction rate of NaOCl (P reaction rate of NaOCl (P > 0.125). The reaction rate of NaOCl with dentine is enhanced by refreshment, ultrasonic activation and exposure time. Temperature rise of irrigant during ultrasonic activation was not sufficient to alter the reaction rate. © 2013 International Endodontic Journal. Published by John Wiley & Sons Ltd.

Correlates of daily leisure-time physical activity in a community sample: Narrow personality traits and practical barriers.

Science.gov (United States)

Gallagher, Patrick; Yancy, William S; Denissen, Jaap J A; Kühnel, Anja; Voils, Corrine I

2013-12-01

Previous studies examining correlates of leisure time physical activity (LTPA) have identified personality factors that are correlated with LTPA and practical factors that impede LTPA. The purpose of the present study was to test how several narrow traits predict daily reports of LTPA and to test whether traits that predict LTPA moderate the effects of practical barriers. 1192 participants completed baseline measures of personality, then reported their LTPA and several situational and environmental factors daily for 25 days. We used generalized estimating equations to measure how personality traits, practical barriers, and interactions between these factors affected (1) the odds of engaging in LTPA and (2) the duration of daily LTPA. Higher standing on Activity and Discipline and lower standing on Assertiveness predicted greater odds of engaging in LTPA and longer duration of LTPA, and higher standing on Aesthetics predicted shorter duration of LTPA. Poor weather conditions and less leisure time were associated with less LTPA, and effects of these barriers were generally greater among participants 30 and older. In participants older than 30, poor weather was associated with less LTPA among those with lower standing on Activity but was not associated with LTPA among those high in Activity. Despite Discipline's overall positive association with LTPA, less leisure time and less routineness were greater barriers for those high in Discipline. Assessing narrow personality traits could help target LTPA interventions to individual patients' needs and could help identify important new personality dynamics that affect LTPA.

Synthesis and electrocatalytic activity towards oxygen reduction reaction of gold-nanostars

Directory of Open Access Journals (Sweden)

Oyunbileg G

2018-02-01

Full Text Available The oxygen reduction reaction (ORR is a characteristic reaction which determines the performance of fuel cells which convert a chemical energy into an electrical energy. Aims of this study are to synthesize Au-based nanostars (AuNSs and determine their preliminary electro-catalytic activities towards ORR by a rotating-disk electrode method in alkaline electrolyte. The images obtained from a scanning electron microscope (SEM and a transmission electron microscope (TEM analyses confirm the formation of the star-shaped nanoparticles. Among the investigated nanostar catalysts, an AuNS5 with smaller size and a few branches showed the higher electrocatalytic activity towards ORR than other catalysts with a bigger size. In addition, the electron numbers transferred for all the catalysts are approximately two. The present study results infer that the size of the Au-based nanostars may influence greatly on their catalytic activity. The present study results show that the further improvement is needed for Au-based nanostar catalysts towards the ORR reaction.

The Diels-Alder Cycloaddition Reaction of Substituted Hemifullerenes with 1,3-Butadiene: Effect of Electron-Donating and Electron-Withdrawing Substituents.

Science.gov (United States)

Mojica, Martha; Méndez, Francisco; Alonso, Julio A

2016-02-12

The Diels-Alder (DA) reaction provides an attractive route to increase the number of six member rings in substituted Polycyclic Aromatic Hydrocarbons (PAHs). The density functional theory (DFT) B3LYP method has been used in this work to inquire if the substitution of H over the edge of triindenetriphenylene (pristine hemifullerene 1) and pentacyclopentacorannulene (pristine hemifullerene 2), could improve the DA cycloaddition reaction with 1,3-butadiene. The substituents tested include electron-donating (NH₂, OMe, OH, Me, i-Pr) and electron-withdrawing groups (F, COOH, CF₃, CHO, CN, NO₂). The electronic, kinetic and thermodynamic parameters of the DA reactions of the substituted hemifullerenes with 1,3-butadiene have been analyzed. The most promising results were obtained for the NO₂ substituent; the activation energy barriers for reactions using this substituent were lower than the barriers for the pristine hemifullerenes. This leads us to expect that the cycloadditions to a starting fullerene fragment will be possible.

Motivators, Facilitators, and Barriers to Physical Activity in Older Adults: A Qualitative Study.

Science.gov (United States)

Miller, Wendy; Brown, Patrick R

In this descriptive, qualitative research study, the researchers used semistructured interviews with older adults who engaged in regular physical activity to identify common motivators, facilitators, and barriers to participating in regular exercise. The authors used these interviews to identify major themes and discuss implications for population health.

Some insights into formamide formation through gas-phase reactions in the interstellar medium

Energy Technology Data Exchange (ETDEWEB)

Redondo, Pilar; Barrientos, Carmen; Largo, Antonio, E-mail: predondo@qf.uva.es [Computational Chemistry Group, Departamento de Química Física, Facultad de Ciencias, Universidad de Valladolid, E-47011 Valladolid (Spain)

2014-01-10

We study the viability of different gas-phase ion-molecule reactions that could produce precursors of formamide in the interstellar medium. We analyze different reactions between cations containing a nitrogen atom (NH{sub 3}{sup +}, NH{sub 4}{sup +}, NH{sub 3}OH{sup +}, and NH{sub 2}OH{sup +}) and neutral molecules having one carbonyl group (H{sub 2}CO and HCOOH). First, we report a theoretical estimation of the reaction enthalpies for the proposed processes. Second, for more favorable reactions, from a thermodynamic point of view, we perform a theoretical study of the potential energy surface. In particular, the more exothermic processes correspond to the reactions of ionized and protonated hydroxylamine with formaldehyde. In addition, a neutral-neutral reaction has also been considered. The analysis of the potential energy surfaces corresponding to these reactions shows that these processes present a net activation barrier and that they cannot be considered as a source of formamide in space.

Many-body treatment of subbarrier fusion reactions

Energy Technology Data Exchange (ETDEWEB)

Iwamoto, Akira; Kondratyev, V. [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Bonasera, A.

1998-07-01

The subbarrier fusion of heavy-ions at energies around the Coulomb barrier is studied by using semiclassical mean-field theory. The paths connecting entrance and exit subbarrier fusion reaction channels are found by incorporating the Wick transformation into the mean-field kinetic equation. The polarization and deformation of nuclei is shown to lower the barrier height. It is demonstrated that preequilibrium nucleon exchange in classically forbidden region gives rise to the nonlocal effects lowering the effective barrier further at small relative distance. (author)

Active living in rural Appalachia: Using the rural active living assessment (RALA tools to explore environmental barriers

Directory of Open Access Journals (Sweden)

Adam Hege

2017-12-01

Full Text Available People residing in rural communities are more likely to be physically inactive and subsequently have elevated risks for chronic disease. Recent evidence has shown this could stem from environmental barriers, inadequate programming and policies directed at the promotion of physical activity (PA in rural settings. The objective of this research was to assess active living features in rural towns and townships (n=16 across seven counties in northwestern North Carolina (NC. The study utilized the Town-Wide and Street Segment components of the Rural Active Living Assessment (RALA as well as the 2014 American Community Survey results. The assessments were conducted in the summer of 2016 in the rural Appalachia region of NC. Using the RALA town-wide assessment scoring system (0−100, the range of scores was 18–84, with the mean being 50.06. Three towns had no sidewalks, nine towns had sidewalks on only one side of the main streets, and four had sidewalks on both sides of the main streets. One town was rated as highly walkable, seven towns as moderately walkable, five towns as moderately unwalkable, and three towns as highly unwalkable. The rural Appalachia region of NC offers unique topographic, geographic and environmental barriers to PA. However, our findings indicate many rural towns offer common PA amenities. Future research should utilize qualitative methods and a community-based participatory research approach to more fully understand the challenges with increasing PA in the rural and often isolated Appalachia communities. Keywords: Rural active living assessment (RALA, Health disparities, Physical activity, Rural Appalachia

Lack of facilities rather than sociocultural factors as the primary barrier to physical activity among female Saudi university students

Directory of Open Access Journals (Sweden)

Samara A

2015-03-01

Full Text Available Anastasia Samara,1 Anne Nistrup,1 Tamader Y AL-Rammah,2 Arja R Aro11Unit for Health Promotion and Research, University of Southern Denmark, Esbjerg, Denmark; 2Faculty of Rehabilitation and Health Sciences, Princess Nora Bint Abdul Rahman University, Riyadh, Kingdom of Saudi ArabiaPurpose: The Kingdom of Saudi Arabia is experiencing a dramatic increase in physical inactivity, with women having higher levels of inactivity than men among all age groups. It is assumed that factors such as dress codes, restrictions on going outdoors, and conservative norms are the main reasons for women’s low physical activity. Our aim was to explore the different parameters related to physical activity, including self-efficacy, as well as the perceived barriers to and benefits of physical activity in young Saudi females.Patients and methods: Ninety-four first-year female Saudi university students in Riyadh, Kingdom of Saudi Arabia, participated in the present study in 2014. The students were from eight bachelor’s programs in health and well-being, and each completed a questionnaire with questions divided into five parts as follows: 1 socioeconomic status, 2 physical activity, 3 self-efficacy 4 social factors, and 5 barriers and facilitators related to physical activity.Results: The students exercised at home and alone, and there was low self-efficacy for physical activity (mean score =42±14. Among social factors, attending university was the only factor that hindered physical activity (32%. Physical activity was positively perceived overall (mean score =131±10. Students showed awareness of the benefits of physical activity for health and well-being. The most important barrier was the lack of designated areas available for physical activity. Students disagreed that family or the Islamic community were barriers to physical activity.Conclusion: The lack of facilities and lack of encouragement from the university, but not a lack of knowledge (a high level of

Perceived barriers to and facilitators of physical activity in recipients of solid organ transplantation, a qualitative study

NARCIS (Netherlands)

van Adrichem, Edwin; van de Zande, Saskia C; Dekker, Rienk; Verschuuren, Erik A M; Dijkstra, Pieter U; van der Schans, Cees

2016-01-01

BACKGROUND: Sufficient physical activity is important for solid organ transplant recipients (heart, lung, liver, kidney). However, recipients do not meet the recommended amount or required type of physical activity. The perceived barriers to and facilitators of physical activity in this population

Perceived Barriers to and Facilitators of Physical Activity in Recipients of Solid Organ Transplantation, a Qualitative Study

NARCIS (Netherlands)

van Adrichem, Edwin J; van de Zande, Saskia C; Dekker, Rienk; Verschuuren, Erik A M; Dijkstra, Pieter U; Schans, van der Cornelis

2016-01-01

Background Sufficient physical activity is important for solid organ transplant recipients (heart, lung, liver, kidney). However, recipients do not meet the recommended amount or required type of physical activity. The perceived barriers to and facilitators of physical activity in this population

Barriers and enabling factors for work-site physical activity programs: a qualitative examination.

Science.gov (United States)

Fletcher, Gena M; Behrens, Timothyh K; Domina, Lorie

2008-05-01

Work sites offer a productive setting for physical activity (PA) promoting interventions. Still, PA participation remains low. Thus, the purpose of this study was to examine the reasoning behind commonly reported barriers and enabling factors to participation in PA programs in a work-site setting. Employees from a large city government were recruited to participate in focus groups, stratified by white- and blue-collar occupations. Responses from open-ended questions about factors influencing participation in PA programs were audio recorded and transcribed verbatim. Resulting data were analyzed with open and axial coding. The sample consisted of 60 employees composing 9 focus groups. Although time was the most common barrier between both groups, white-collars workers responded that scheduling and work conflicts were the most common barrier concerning time. Blue-collar workers indicated shift work as their most common barrier. In addition, health was a significant enabling factor for both occupational categories. White-collar workers were much more concerned with appearances and were more highly motivated by weight loss and the hopefulness of quick results than were blue-collar workers. These findings are important in the understanding of PA as it relates to the reasoning behind participation in work-site programs in regard to occupational status.

Breast cancer survivors' barriers and motives for participating in a group-based physical activity program offered in the community.

Science.gov (United States)

Wurz, Amanda; St-Aubin, Anik; Brunet, Jennifer

2015-08-01

The purpose of this qualitative study was to explore the barriers and motives experienced by women attending an 8-week group-based physical activity program offered in the community following treatment for breast cancer. Seven women were interviewed during the first and last week of the program. Data were analyzed using thematic analysis. Factors that hindered women's continued participation could be subdivided into situational barriers, which encompassed community (i.e., distance of center and traffic) and institutional factors (i.e., competing roles and responsibilities), and internal barriers, which consisted of cancer-specific limitations. Motives for initial and continued participation were situational (i.e., gaining social support, networking, and being around similar others) and internal (i.e., feeling a sense of personal fulfillment, acquiring health benefits, and recovering from cancer). The findings contribute to a deeper understanding of women's motives to engage in a group-based physical activity program after treatment for breast cancer. Further, they underscore the necessity of considering situational and internal barriers when developing group-based physical activity programs to increase regular participation, optimize adherence, and reduce drop-out.

Combustion chemical vapor desposited coatings for thermal barrier coating systems

Energy Technology Data Exchange (ETDEWEB)

Hampikian, J.M.; Carter, W.B. [Georgia Institute of Technology, Atlanta, GA (United States)

1995-10-01

The new deposition process, combustion chemical vapor deposition, shows a great deal of promise in the area of thermal barrier coating systems. This technique produces dense, adherent coatings, and does not require a reaction chamber. Coatings can therefore be applied in the open atmosphere. The process is potentially suitable for producing high quality CVD coatings for use as interlayers between the bond coat and thermal barrier coating, and/or as overlayers, on top of thermal barrier coatings.

Evaluation and analysis of barriers to the innovation activity in the economy of the region

Directory of Open Access Journals (Sweden)

D. A. Tomasova

2017-01-01

Full Text Available Prospects for the development of the Russian innovative economy largely depend on the successful overcoming of negative factors impeding the effective interaction of institutions in the field of education, science, business, credit and fi nancial sphere regarding the creation, transfer and commercialization of innovations. Deep evaluation of innovative problems needs dynamic analysis of main processes in the spheres accompanying the innovation activity, which determines the topicality of this article. The aim of research consists in elaborating a dynamic approach to complex estimation of problems and barriers to the innovative development of Russia, including their structure and change. In order to do that, this article reviews the main barriers to the development of innovation activity in the region, builds a detailed classifi cation of parameters of innovative economic environment, and analyses their dynamics. The algorithm of innovation barriers assessment is based on economic statistics methods and fuzzy sets theory. This algorithm is determined on the basis of linguistic variables according to the matrix principle and linguistic identifi cation of economic objects. The estimation is based on a dynamic approach, that is, each analyzed indicator represents a rate of growth of one or another factor associated with the level of barriers to the innovation activity and therefore reflects the degree of reduction or strengthening in such barrier for the period under review. The minimax normalization allows providing comparability of all indicators under review. Macroeconomic data and indices of Russian enterprises operation, presented in statistical collections were used as the input data for analysis and estimation. As a result, we evaluated the level of overcoming barriers to innovative development during the past three years on the basis of analyzing research human potential, of development of innovative infrastructure