On the role of a new type of correlated disorder in extended electronic states in the Thue-Morse lattice

A new type of correlated disorder is shown to be responsible for the appearance of extended electronic states in one-dimensional aperiodic systems like the Thue-Morse lattice. Our analysis leads to an understanding of the underlying reason for the extended states in this system, for which only numerical evidence is available in the literature so far. The present work also sheds light on the restrictive conditions under which the extended states are supported by this lattice.Comment: 11 pages, LaTeX V2.09, 1 figure (available on request), to appear in Physical Review Letter

Limit load based evaluation of plastic ? factor for C(T) specimen with a mismatched weld

Plastic ? factor is adopted to account for crack tip plasticity while evaluating the fracture toughness of the materials as per ASTM E1820. It is valid only for homogeneous materials. The plastic ? factor for Compact Type (C(T)) geometry with type 316LN stainless steel weld has been evaluated based on elastic-plastic FE analysis. The incremental elastic-plastic material model with various values for strength mismatch ratio (M) i.e. ratio of yield strength of weld metal to that of base metal, from 1.2 to 2.2 have been considered. The weld width (h) parallel to the crack plane is varied from 4 mm to 16 mm. The ? values thus obtained are analyzed and the inferences are discussed

Outdoor recreational activity experiences improve psychological wellbeing of military veterans with post-traumatic stress disorder: Positive findings from a pilot study and a randomised controlled trial

Exposure to the natural environment is increasingly considered to benefit psychological health. Recent reports in the literature also suggest that outdoor exposure that includes recreational pursuits such as surfing or fishing coupled with opportunities for social interaction with peers may be beneficial to Armed Forces Veterans experiencing Post-Traumatic Stress Disorder (PTSD). Two studies were conducted to evaluate this possibility. In particular, these studies aimed to test the hypothesis that a brief group outdoor activity would decrease participants’ symptoms as assessed by established measures of PTSD, depression, anxiety and perceived stress, and increase participants’ sense of general social functioning and psychological growth. Experiment one employed a repeated measures design in which UK men and women military veterans with PTSD (N = 30) participated in a group outdoor activity (angling, equine care, or archery and falconry combined). Psychological measures were taken at 2 weeks prior, 2 weeks post, and at 4 month follow up. We obtained a significant within participant main effect indicating significant reduction in PTSD symptoms. Experiment two was a waitlist controlled randomised experiment employing an angling experience (N = 18) and 2 week follow up. In experiment 2 the predicted interaction of Group (Experimental vs. Waitlist Control) X Time (2 weeks pre vs. 2 weeks post) was obtained indicating that the experience resulted in significant reduction in PTSD symptoms relative to waitlist controls. The effect size was large. Additional analyses confirmed that the observed effects might also be considered clinically significant and reliable. In sum, peer outdoor experiences are beneficial and offer potential to complement existing provision for military veterans with Post Traumatic Stress Disorder

Limit load based evaluation of plastic η factor for C(T) specimen with a mismatched weld

Plastic η factor is adopted to account crack tip plasticity while evaluating the fracture toughness of the materials as per ASTM E1820. It is valid only for homogeneous materials. The plastic η factor for compact tension geometry (CT) with type 316LN stainless steel weld has been evaluated based on elastic-plastic FE analysis. The incremental elastic-plastic material model with various values for strength mismatch level (M), from 1.2 to 2.2 has been considered for the weld. The weld width (h) parallel to the crack plane is varied from 4 mm to 16 mm. The η values thus obtained are analyzed and the inferences are discussed

Quasicrystals: Making invisible materials

All-dielectric photonic quasicrystals may act as zero-refractive-index homogeneous materials despite their lack of translational symmetry and periodicity, stretching wavelengths to infinity and offering applications in light wavefront sculpting and optical cloaking.Comment: 5 pages, 2 figure

Extended states in 1D lattices: application to quasiperiodic copper-mean chain

The question of the conditions under which 1D systems support extended electronic eigenstates is addressed in a very general context. Using real space renormalisation group arguments we discuss the precise criteria for determining the entire spertrum of extended eigenstates and the corresponding eigenfunctions in disordered as well as quasiperiodic systems. For purposes of illustration we calculate a few selected eigenvalues and the corresponding extended eigenfunctions for the quasiperiodic copper-mean chain. So far, for the infinite copper-mean chain, only a single energy has been numerically shown to support an extended eigenstate [ You et al. (1991)] : we show analytically that there is in fact an infinite number of extended eigenstates in this lattice which form fragmented minibands.Comment: 10 pages + 2 figures available on request; LaTeX version 2.0

Design and feasibility testing of a novel group intervention for young women who binge drink in groups

BackgroundYoung women frequently drink alcohol in groups and binge drinking within these natural drinking groups is common. This study describes the design of a theoretically and empirically based group intervention to reduce binge drinking among young women. It also evaluates their engagement with the intervention and the acceptability of the study methods.MethodsFriendship groups of women aged 18–35 years, who had two or more episodes of binge drinking (>6 UK units on one occasion; 48g of alcohol) in the previous 30 days, were recruited from the community. A face-to-face group intervention, based on the Health Action Process Approach, was delivered over three sessions. Components of the intervention were woven around fun activities, such as making alcohol free cocktails. Women were followed up four months after the intervention was delivered. Results The target of 24 groups (comprising 97 women) was recruited. The common pattern of drinking was infrequent, heavy drinking (mean consumption on the heaviest drinking day was UK 18.1 units). Process evaluation revealed that the intervention was delivered with high fidelity and acceptability of the study methods was high. The women engaged positively with intervention components and made group decisions about cutting down. Twenty two groups set goals to reduce their drinking, and these were translated into action plans. Retention of individuals at follow up was 87%.ConclusionsThis study successfully recruited groups of young women whose patterns of drinking place them at high risk of acute harm. This novel approach to delivering an alcohol intervention has potential to reduce binge drinking among young women. The high levels of engagement with key steps in the behavior change process suggests that the group intervention should be tested in a full randomised controlled trial