Quantitative assessment of through-thickness crack size based on Lamb wave scattering in aluminium plates

The interaction of Lamb wave modes at varying frequencies with a through-thickness crack of different lengths in aluminium plates was analysed in terms of finite element method and experimental study. For oblique-wave incidence, both numerical and experimental results showed that the wave scattering from a crack leads to complicated transmission, reflection and diffraction accompanied by possible wave-mode conversion. A dual-PZT actuation scheme was therefore applied to generate the fundamental symmetrical mode (S0) with enhanced energy to facilitate the identification of crack-scattered wave components. The relationship between crack length and the reflection/transmission coefficient obtained with the aid of the Hilbert transform was established, through which the crack length was quantitatively evaluated. The effects of wavelength of Lamb waves and wave diffraction on the properties of the reflection and transmission coefficients were analysed.

Job stress in the law enforcement sector: comparing the linear, non-linear and interaction effects of working conditions

This study addresses a gap in much of the research involving stress among high-risk occupations by investigating the effects of linear, non-linear and interaction models in a law enforcement organization that has undertaken a series of efficiency-driven organizational reforms. The results of a survey involving 2085 police officers indicated that the demand-control-support model provided good utility in predicting an officer's satisfaction, commitment and well-being. In particular, social support and job control were closely associated with all three outcome variables. Although the demand × control/support interactions were not identified in the data, there was some support for the curvilinear effects of job demands. The results have implications for the organizational conditions that need to be addressed in contemporary policing environments where new public management strategies have had widespread affects on the social and organizational context in which policing takes place.

Re-imagining the cultural brand : postmodernism and next wave

The traditional interpretation of a brand, and the means by which an organisation communicates its brand, might be considered a product of a modernist managerial paradigm, with its focus on consistency, control, and coherence (Brown 1995, 1999; Firat and Shultz 1997). With the emergence of postmodernism, this logic has been challenged by one of flexibility and openness, since consumers are no longer willing to commit or conform to any unified and consistent idea, system, or narrative. In order to explain this change in the management of brands, this paper will examine the Australian cultural brand, Next Wave, as a paradigmatic example. Next Wave offers an innovative brand management model founded on the interaction between the organisation and the content provider, i.e., the artist. Based on both aesthetic and conceptual experimentations, Next Wave is a dynamic brand in which shape and content are continually redefined in an interactive and mutual relationship between the artist and the organisation. Therefore, it can be argued that paradoxically, the organisation does not own its own brand. In fact, the ownership exists only from a legal point of view (as a trademark); the real artificer of the brand is the artist. Since it is not possessed nor controlled at all by the organisation, but is always subject to continuous evolutions and redefinitions, the Next Wave brand can be considered as a postmodern brand that is not strictly tied to marketing rules, but involves the target as an active participant in the brand creation process.

The interaction of lipophilic drugs with intestinal fatty acid-binding protein

Intestinal fatty acid-binding protein (I-FABP) is a small protein that binds long-chain dietary fatty acids in the cytosol of the columnar absorptive epithelial cells (enterocytes) of the intestine. The binding cavity of I-FABP is much larger than is necessary to bind a fatty acid molecule, which suggests that the protein may be able to bind other hydrophobic and amphipathic ligands such as lipophilic drugs. Herein we describe the binding of three structurally diverse lipophilic drugs, bezafibrate, ibuprofen (both R- and S-isomers) and nitrazepam to I-FABP. The rank order of affinity for I-FABP determined for these compounds was found to be R-ibuprofen {approx} bezafibrate > S-ibuprofen >> nitrazepam. The binding affinities were not directly related to aqueous solubility or partition coefficient of the compounds; however, the freely water-soluble drug diltiazem showed no affinity for I-FABP. Drug-I-FABP interaction interfaces were defined by analysis of chemical shift perturbations in NMR spectra, which revealed that the drugs bound within the central fatty acid binding cavity. Each drug participated in a different set of interactions within the cavity; however, a number of common contacts were observed with residues also involved in fatty acid binding. These data suggest that the binding of non-fatty acid lipophilic drugs to I-FABP may increase the cytosolic solubility of these compounds and thereby facilitate drug transport from the intestinal lumen across the enterocyte to sites of distribution and metabolism.

Extreme surfing : personal and psychological aspects of big wave riders

This qualitative study investigated personal and psychological aspects of big wave riders. A cross-sectional design with non probability purposive sampling was used to gain personal interviews with 32 elite surfers who regularly ride big, life threatening waves. Each athlete was asked three open questions: 1. What do you think are the most important qualities and attributes a surfer needs for riding big waves? 2. What type of mindset is best for riding big waves?, and 3.What motivates you to ride big waves? Content analysis of the taped interview transcripts revealed seven key qualities and attributes including having a thrill seeking, confident and goal oriented personality, a high level of mental strength and control, and an intimate relationship with the ocean. The best mindset included an individually defined arousal level, a committed attitude, and a simple, yet highly aware, focus. Motivations were primarily intrinsic, though drives indicative of a behavioral addiction to the act of riding big waves also emerged. Evidence of common developmental stages for riding big waves also arose from the interviews. Optimal mental approach and preparation techniques are discussed that will enable big wave riders, and other extreme athletes, to more safely and successfully manage extreme situations.

The miscibility of poly(d,l-lactide-co-glycolide) with amphiphilic molecules and the interaction of their mixtures with DNA at air/water interface

The miscibility of poly(d,l-lactide-co-glycolide) (PLG) with three amphiphilic molecules and the interaction of the PLG/surfactant mixtures with DNA at air/water interface are investigated by π-A isotherms, Brewster angle microscopy (BAM) and atomic force microscopy (AFM) techniques. The π-A isotherms of the PLG mixtures with cationic C12AzoC6PyBr, and C12AzoC6N(CH3)3Br, are quite different from the π-A isotherm of pure PLG on water subphase. In contrast to the case, the π-A isotherm of PLG mixed with nonionic C12AzoC6OPy is almost identical to the pure PLG except some increasing of molecular area. Similar phenomena are observed on DNA subphase. The in situ BAM and ex situ AFM observations demonstrate that the dispersion of PLG at air/water interface becomes good when it mixes with the two cationic surfactants, whereas quite poor due to the phase separation when it mixes with the nonionic amphiphilic molecule. Based on these results we conclude that the cationic surfactants can affect the conformation change of PLG at air/water interface and figure a well miscibility with polymer whereas the nonionic amphiphilic molecule presents poor miscibility. In addition, the even mixing of the PLG and the cationic surfactants is favorable for the adsorption to DNA more effectively.

Crime risks of three-dimensional virtual environments

Three-dimensional virtual environments (3dves) are the new generation of digital multi-user social networking platforms. Their immersive character allows users to create a digital humanised representation or avatar, enabling a degree of virtual interaction not possible through conventional text-based internet technologies. As recent international experience demonstrates, in addition to the conventional range of cybercrimes (including economic fraud, the dissemination of child pornography and copyright violations), the 'virtual-reality' promoted by 3dves is the source of great speculation and concern over a range of specific and emerging forms of crime and harm to users. This paper provides some examples of the types of harm currently emerging in 3dves and suggests internal regulation by user groups, terms of service, or end-user licensing agreements, possibly linked to real-world criminological principles. This paper also provides some directions for future research aimed at understanding the role of Australian criminal law and the justice system more broadly in this emerging field.

Organisational and national culture : a study of overlap and interaction in the Literature

Terms such as Globalisation and cross-cultural management are widely used by both organisational managers and academics. While it is the intention of academics and industry analysts to explain the phenomena and discover principles to guide the practitioners, human resource managers are dealing with the workplace changes implicit in these terms on an increasingly frequent basis. These managers are facing increasingly diverse workforces, and must cope with all the challenges and opportunities inherent in such diversity. This article presents a new approach to examining the key literature on organisational and national culture in three main areas. Firstly, areas of convergence between various theories on culture are identified. Secondly, the article illustrates and discusses where these theories diverge from each other. Thirdly, drawing on the principles discussed in the article, a framework of national culture is developed from existing literature that highlights the convergence found in existing models.

Three-month bilateral hopping intervention is ineffective in initiating bone biomarker response in healthy elderly men.

In animal studies, bone adaptation has been initiated successfully without the transient force spike associated with high impact exercises. Consequently, a 12-week bilateral hopping on the balls of the feet intervention was conducted. 25 elderly men (age 72(SD4) years, height 171(6) cm, weight 75(9) kg) were randomly assigned into exercise and control groups. Ten subjects in each group completed the study. Carboxyterminal propeptide of type I collagen (CICP), bone-specific alkaline phosphatase (bALP) and carboxyterminal telopeptide of type I collagen (CTx) were measured from venous blood samples at baseline, at 2 weeks and at the end of the intervention. Maximal ground reaction force (GRF), osteogenic index (OI) and jump height (JH) were determined from bilateral hopping test and balance was assessed with velocity of center of pressure (COPvelocity) while standing on the preferred leg with eyes open. The intervention consisted of 5–7 sets of 10 s timed bilateral hopping exercise at 75–90% intensity three times/week. There was no significant group 9 time interaction for GRF, OI and JH (P = 0.065). GRF (11% change from baseline vs. 4%), OI (15 vs. 6%) and COPvelocity (-10 vs. -1%) were not influenced by the intervention (P[0.170), while the control group improved JH (P = 0.031) (2 vs. 18%). For the biomarkers, no effect was observed in MANOVA (P = 0.536) or in univariate analyses (P = 0.082 to P = 0.820) (CICP -2 vs. -3%, CTx 8 vs. -12%, bALP 0 vs. -3.7%). Allowing transient impact force spikes may be necessary to initiate a bone response in elderly men as the intervention was ineffective.

Gene-environment interaction in problematic substance use : interaction between DRD4 and insecure attachments

To investigate the combined effect of an exon III variable number tandem repeat in the dopamine receptor gene (DRD4) and insecure attachment style on risk for tobacco, cannabis and alcohol use problems in young adulthood. It was hypothesized that (1) individuals with 5, 6, 7 or 8 repeats (labelled 7R+) would be at increased risk for problematic drug use, and (2) risk for drug use would be further increased in individuals with 7R+ repeats who also have a history of insecure parent–child attachment relations. Data were drawn from the Victorian Adolescent Health Cohort Study, an eight-wave longitudinal study of adolescent and young adult development. DRD4 genotypes were available for 839 participants. Risk attributable to the combined effects of 7R+ genotype and insecure attachments was evaluated within a sufficient causes framework under the assumptions of additive interaction using a two-by-four table format with a common reference group. 7R+ alleles were associated with higher tobacco, cannabis and alcohol use (binging). Insecure attachments were associated with higher tobacco and cannabis use but lower alcohol use. For tobacco, there was evidence of interaction for anxious but not avoidant attachments. For cannabis, there was evidence of interaction for both anxious and avoidant attachments, although the interaction for anxious attachments was more substantial. There is no evidence of interaction for binge drinking. Results are consistent with a generic reward deficit hypothesis of drug addiction for which the 7R+ disposition may play a role. Interaction between 7R+ alleles and attachment insecurity may intensify risk for problematic tobacco and cannabis use.

Two-dimensional correlation localized surface plasmon resonance spectroscopy for analysis of the interaction between metal nanoparticles and bovine serum albumin

Time-resolved extinction spectra assisted with two-dimensional correlation spectroscopy (2DCOS) analysis and principal component analysis (PCA) were employed to investigate the interaction between bovine serum albumin (BSA) and metal nanoparticles (NPs). A series of localized surface plasmon resonance (LSPR) spectra of metal NPs were measured just after a small amount of BSA was added into metal colloids. Through 2DCOS analysis, remarkable changes in the intensities of the LSPR were observed. The interaction process was totally divided into three periods according to the PCA. Transmission electron microscopy, dynamic light scattering, and ζ-potential measurements were also employed to characterize the interaction between BSA and metal NPs. The addition of BSA brings silver NPs to aggregate through the electrostatic interaction between them, but it has less effect on gold NPs. In a gold and silver mixed system, gold NPs can affect the interaction of silver NPs and BSA, leading it to weaken. The combination of 2DCOS analysis and LSPR spectroscopy is powerful for exploring the LSPR spectra of the metal NP involved systems. This combined technique holds great potential in LSPR sensing through analysis of slight, slim spectral changes of metal colloids

Three year follow-up of an early childhood intervention : is movement skill sustained?

Background
Movement skill competence (e.g. the ability to throw, run and kick) is a potentially important physical activity determinant. However, little is known about the long-term impact of interventions to improve movement skills in early childhood. This study aimed to determine whether intervention preschool children were still more skill proficient than controls three years after a 10 month movement skill focused intervention: ‘Tooty Fruity Vegie in Preschools’.

Methods
Children from 18 intervention and 13 control preschools in NSW, Australia were assessed at ages four (Time1), five (T2) and eight years (T3) for locomotor (run, gallop, hop, leap, horizontal jump, slide) and object control proficiency (strike, bounce, catch, kick, overhand throw, underhand roll) using the Test of Gross Motor Development-2. Multi-level object control and locomotor regression models were fitted with variables time, intervention (yes/no) and a time*intervention interaction. Both models added sex of child and retained if significant, in which case interactions of sex of child with other variables were modelled and retained. SPSS (Version 17.0) was used.

Results
Overall follow-up rate was 29% (163/560). Of the 137 students used in the regression models, 53% were female (n = 73). Intervention girls maintained their object control skill advantage in comparison to controls at T3 (p = .002), but intervention boys did not (p = .591). At T3, there were no longer intervention/control differences in locomotor skill (p = .801).

Conclusion
Early childhood settings should implement movement skill interventions and more intensively target girls and object control skills.

Guided wave based methods for damage detection : experimental study on concrete joint

Since Guided wave (GW) is sensitive to small damage and can propagate a relatively longer distance with relatively less attenuation, GW-based method has been found as an effective and efficient way to detect incipient damages. In this study, a full-scale concrete joint was constructed to further verify the effectiveness of GW-based method on real civil structures. GW tests were conducted in three stages, including baseline, serviceability and damage conditions. The waves are excited by one actuator and received by several sensors, which are made up of independent piezoelectric elements. Experimental results show that the mehod is promising for damage identification in practices.

The electrochemical surface forces apparatus : the effect of surface roughness, electrostatic surface potentials, and anodic oxide growth on interaction forces, and friction between dissimilar surfaces in aqueous solutions

We present a newly designed electrochemical surface forces apparatus (EC-SFA) that allows control and measurement of surface potentials and interfacial electrochemical reactions with simultaneous measurement of normal interaction forces (with nN resolution), friction forces (with μN resolution), and distances (with Å resolution) between apposing surfaces. We describe three applications of the developed EC-SFA and discuss the wide-range of potential other applications. In particular, we describe measurements of (1) force–distance profiles between smooth and rough gold surfaces and apposing self-assembled monolayer-covered smooth mica surfaces; (2) the effective changing thickness of anodically growing oxide layers with Å-accuracy on rough and smooth surfaces; and (3) friction forces evolving at a metal–ceramic contact, all as a function of the applied electrochemical potential. Interaction forces between atomically smooth surfaces are well-described using DLVO theory and the Hogg–Healy–Fuerstenau approximation for electric double layer interactions between dissimilar surfaces, which unintuitively predicts the possibility of attractive double layer forces between dissimilar surfaces whose surface potentials have similar sign, and repulsive forces between surfaces whose surface potentials have opposite sign. Surface roughness of the gold electrodes leads to an additional exponentially repulsive force in the force–distance profiles that is qualitatively well described by an extended DLVO model that includes repulsive hydration and steric forces. Comparing the measured thickness of the anodic gold oxide layer and the charge consumed for generating this layer allowed the identification of its chemical structure as a hydrated Au(OH)3 phase formed at the gold surface at high positive potentials. The EC-SFA allows, for the first time, one to look at complex long-term transient effects of dynamic processes (e.g., relaxation times), which are also reflected in friction forces while tuning electrochemical surface potentials.

Short-interval intracortical inhibition is not affected by varying visual feedback in an isometric task in biceps brachiii muscle

Purpose : To establish if visual feedback and force requirements influence SICI.

Methods : SICI was assessed from 10 healthy adults (5 males and 5 females aged between 21 and 35 years) in three submaximal isometric elbow flexion torque levels [5, 20, and 40% of maximal voluntary contraction (MVC)] and with two tasks differing in terms of visual feedback. Single-pulse and paired-pulse motor-evoked potentials (MEPs), supramaximal M-wave, and background surface electromyogram (sEMG) were recorded from the biceps brachii muscle.

Results : Repeated measures MANOVA was used for statistical analyses. Background sEMG did not differ between tasks (F = 0.4, P = 0.68) nor was task × torque level interaction observed (F = 1.2, P = 0.32), whereas background sEMG increased with increasing torque levels (P = 0.001). SICI did not differ between tasks (F = 0.9, P = 0.43) and no task × torque level interaction was observed (F = 2.3, P = 0.08). However, less SICI was observed at 40% MVC compared to the 5 and 20% MVC torque levels (P = 0.01–0.001).

Conclusion : SICI was not altered by performing the same task with differing visual feedback. However, SICI decreased with increasing submaximal torque providing further evidence that SICI is one mechanism of modulating cortical excitability and plays a role in force gradation.