An Effective Theory for Midgap States in Doped Spin Ladder and Spin-Peierls Systems: Liouville Quantum Mechanics

In gapped spin ladder and spin-Peierls systems the introduction of disorder, for example by doping, leads to the appearance of low energy midgap states. The fact that these strongly correlated systems can be mapped onto one dimensional noninteracting fermions provides a rare opportunity to explore systems which have both strong interactions and disorder. In this paper we show that the statistics of the zero energy midgap wave functions in these models can be effectively described by Liouville Quantum Mechanics. This enables us to calculate the disorder averaged N-point correlation functions of these states (the explicit calculation is performed for N=2,3). We find that whilst these midgap states are typically weakly correlated, their disorder averaged correlation are power law. This discrepancy arises because the correlations are not self-averaging and averages of the wave functions are dominated by anomalously strongly correlated configurations.Comment: 13 page latex fil

Yoga in school-aged children: Impact on children's mental health and well-being during the COVID-19 pandemic – A protocol

The rapid spread of COVID-19 and the increasing burden on mental health and well- being require new ways of supporting families that have to maintain the new norms of social distancing. Many families may be under enormous amounts of stress and anxiety caused by losing their loved ones. Therefore, there is a great need to search for ways to minimize the effects of COVID-19 on mental health and well-being. The purpose of the research is to evaluate a yoga intervention offered online to school-aged children in the U.K. by Patanjali Yog Peeth Trust U.K. (PYPT) and evaluate its effectiveness by interviewing the parents of participating children. The project will seek to promote an additional tool in managing mental health and well-being in school-aged children. The research will use a mixed-methods approach. Parents will be approached by a PYPT yoga teacher and invited to complete an online survey and quantitative interview. Parents (over 18 years) of school-aged children (5-16 years) who live in the U.K. are eligible to take part. Upon gaining consent, participates will be asked to complete a parent and child characteristic questionnaire. An SDQ survey for parents via online Opinio and a subsample will be interviewed using a structured interview schedule. All analyses will be carried out in SPSS. It is intended that the research will provide an evidence base that will aid future studies and inform in developing yoga interventions that may aid in promoting child mental health and well-being. The study results will be published in peer-reviewed international journals; the researchers will also present the results at governmental conferences

Transition of Attention in Terminal Area NextGen Operations Using Synthetic Vision Systems

This experiment investigates the capability of Synthetic Vision Systems (SVS) to provide significant situation awareness in terminal area operations, specifically in low visibility conditions. The use of a Head-Up Display (HUD) and Head-Down Displays (HDD) with SVS is contrasted to baseline standard head down displays in terms of induced workload and pilot behavior in 1400 RVR visibility levels. Variances across performance and pilot behavior were reviewed for acceptability when using HUD or HDD with SVS under reduced minimums to acquire the necessary visual components to continue to land. The data suggest superior performance for HUD implementations. Improved attentional behavior is also suggested for HDD implementations of SVS for low-visibility approach and landing operations

Molecular Acoustic Angiography: A New Technique for High-resolution Superharmonic Ultrasound Molecular Imaging

Ultrasound molecular imaging utilizes targeted microbubbles to bind to vascular targets such as integrins, selectins, and other extracellular binding domains. After binding, these microbubbles are typically imaged using low pressures and multi-pulse imaging sequences. In this article, we present an alternative approach for molecular imaging using ultrasound which relies on superharmonic signals produced by microbubble contrast agents. Bound bubbles were insonified near resonance using a low frequency (4 MHz) and superharmonic echoes were received at high frequencies (25–30 MHz). While this approach was observed to produce declining image intensity during repeated imaging in both in vitro and in vivo experiments due to bubble destruction, the feasibility of superharmonic molecular imaging was demonstrated for transmit pressures which are sufficiently high to induce shell disruption in bound microbubbles. This approach was validated using microbubbles targeted to the αvβ3 integrin in a rat fibrosarcoma model (n=5), and combined with superharmonic images of free microbubbles to produce high contrast, high resolution 3D volumes of both microvascular anatomy and molecular targeting. Image intensity over repeated scans and the effect of microbubble diameter were also assessed in vivo, indicating that larger microbubbles yield increased persistence in image intensity. Using ultrasound-based acoustic angiography images rather than conventional B-mode ultrasound to provide the underlying anatomical information facilitates anatomical localization of molecular markers. Quantitative analysis of relationships between microvasculature and targeting information indicated that most targeting occurred within 50 µm of a resolvable vessel (>100 µm diameter). The combined information provided by these scans may present new opportunities for analyzing relationships between microvascular anatomy and vascular targets, subject only to limitations of the current mechanically-scanned system and microbubble persistence to repeated imaging at moderate mechanical indices

Total hip replacement: improving cement fixation of the acetabular component

The primary aim of this study was to propose fixation techniques that would improve the cement fixation of the acetabular cup. This was done by (1) studying current practice, (2) creating FE models of the reconstructed acetabulum to predict improved fixation techniques, (3) validating the FE models by laboratory investigations and (4) proposing designs of jigs and drill bit that would assist orthopaedic surgeons use the recommended techniques

The discomforting rise of ' public geographies': a 'public' conversation.

In this innovative and provocative intervention, the authors explore the burgeoning ‘public turn’ visible across the social sciences to espouse the need to radically challenge and reshape dominant and orthodox visions of ‘the academy’, academic life, and the role and purpose of the academic

Optical absorption of spin ladders

We present a theory of phonon-assisted optical two-magnon absorption in two-leg spin-ladders. Based on the strong intra-rung-coupling limit we show that collective excitations of total spin S=0, 1 and 2 exist outside of the two-magnon continuum. It is demonstrated that the singlet collective state has a clear signature in the optical spectrum.Comment: 4 pages, 3 figure