An analysis of the effect of a particular class of PFM on noise inputs

Statistical analysis of pulse frequency modulation systems with white noise inpu

Quantifying Finite Temperature Effects in Atom Chip Interferometry of Bose-Einstein Condensates

We quantify the effect of phase fluctuations on atom chip interferometry of Bose-Einstein condensates. At very low temperatures, we observe small phase fluctuations, created by mean-field depletion, and a resonant production of vortices when the two clouds are initially in anti-phase. At higher temperatures, we show that the thermal occupation of Bogoliubov modes makes vortex production vary smoothly with the initial relative phase difference between the two atom clouds. We also propose a technique to observe vortex formation directly by creating a weak link between the two clouds. The position and direction of circulation of the vortices is subsequently revealed by kinks in the interference fringes produced when the two clouds expand into one another. This procedure may be exploited for precise force measurement or motion detection.Comment: 7 pages, 5 figure

Regional variation in digital cushion pressure in the forefeet of horses and elephants

In this study, we seek to understand how the digital cushion morphologies evident in horse and elephant feet influence internal and external foot pressures. Our novel use of invasive blood pressure monitoring equipment, combined with a pressure pad and force plate, enabled measurements of (ex vivo) digital cushion pressure under increasing axial loads in seven horse and six elephant forefeet. Linear mixed effects models (LMER) revealed that internal digital cushion pressures increase under load and differ depending on region; elephant feet experienced higher magnitudes of medial digital cushion pressure, whereas horse feet experienced higher magnitudes of centralised digital cushion pressure. Direct comparison of digital cushion pressure magnitudes in both species, at equivalent loads relative to body weight, revealed that medial and lateral pressures increased more rapidly with load in elephant limbs. Within the same approximate region, internal pressures exceeded external, palmar pressures (on the sole of the foot), supporting previous Finite Element (FE) predictions. High pressures and large variations in pressure may relate to the development of foot pathology, which is a major concern in horses and elephants in a captive/domestic environment

The impact of mutation and gene conversion on the local diversification of antigen genes in African trypanosomes

Patterns of genetic diversity in parasite antigen gene families hold important information about their potential to generate antigenic variation within and between hosts. The evolution of such gene families is typically driven by gene duplication, followed by point mutation and gene conversion. There is great interest in estimating the rates of these processes from molecular sequences for understanding the evolution of the pathogen and its significance for infection processes. In this study, a series of models are constructed to investigate hypotheses about the nucleotide diversity patterns between closely related gene sequences from the antigen gene archive of the African trypanosome, the protozoan parasite causative of human sleeping sickness in Equatorial Africa. We use a hidden Markov model approach to identify two scales of diversification: clustering of sequence mismatches, a putative indicator of gene conversion events with other lower-identity donor genes in the archive, and at a sparser scale, isolated mismatches, likely arising from independent point mutations. In addition to quantifying the respective probabilities of occurrence of these two processes, our approach yields estimates for the gene conversion tract length distribution and the average diversity contributed locally by conversion events. Model fitting is conducted using a Bayesian framework. We find that diversifying gene conversion events with lower-identity partners occur at least five times less frequently than point mutations on variant surface glycoprotein (VSG) pairs, and the average imported conversion tract is between 14 and 25 nucleotides long. However, because of the high diversity introduced by gene conversion, the two processes have almost equal impact on the per-nucleotide rate of sequence diversification between VSG subfamily members. We are able to disentangle the most likely locations of point mutations and conversions on each aligned gene pair

Biodiversity-rich European grasslands : ancient, forgotten ecosystems

Worldwide reforestation has been recommended as a landscape restoration strategy to mitigate climate change in areas where the climate can sustain forest. This approach may threaten grassland ecosystems of unique biodiversity as such policies are based on the false assumption that most grasslands are man-made. Here, we use multiple lines of evidence (palaeoecological, pedological, phylogenetic, palaeontological) from Central Eastern Europe and show that various types of grasslands have persisted in this area throughout the postglacial i.e., the past 11,700 years. A warm and dry climate, frequent fires, herbivore pressure and early Neolithic settlements kept forests open until widespread forest clearance beginning 4000 to 3000 years ago. Closed forest cover has been the exception for the last two million years. This long-term persistence has likely contributed to the high biodiversity of these grasslands. Consequently, we call for a more cautious prioritisation of the protection of what may be erroneously considered natural, i.e. forests, by many environmental specialists and managers. Instead we provide a new framework for a better understanding of the evolution and persistence of different grassland types and their biodiversity, so that grasslands can be better understood, valued and conserved

The experience of school-based dramatherapists: Understanding the barriers and facilitators of UK school-based dramatherapy to inform better implementation

Approximately 50% of UK dramatherapists deliver their work in schools. Despite this, little is currently known about the way in which school settings affect the dramatherapy that is delivered within them. This qualitative investigation utilised semi-structured interviews (N = 12) and reflexive thematic analysis to identify the facilitators and barriers of providing dramatherapy in school settings. In addition, the unique experiences of working as a dramatherapist in a school setting were also investigated. Amongst others, the facilitators identified included school as an accessible and safe place for therapy to occur. In addition, the structure provided by the school's daily and annual timetable, and the support of other school-based professionals and organisations were also identified. The barriers identified related to funding challenges, inappropriate referrals, schools seeking quick results and a lack of access to suitable spaces for therapy to occur. Regarding their experiences of employment, many dramatherapists spoke of working in multiple schools and, whilst some enjoyed the flexibility this offered, many found it challenging to become part of the school community and experienced a sense of isolation whilst working. Feeling like they are lower paid than clinical counterparts, such as colleagues in Child and Adolescent Mental Health Services (CAMHS), was also raised by those interviewed. These findings suggest that resource investment and investment into teachers’ and other school-based professionals’ knowledge of dramatherapy is warranted. In addition, dramatherapists who work in schools may benefit from community building. Future research, which explores the experience of dramatherapists in other settings is also encouraged

Therapist perceived active ingredients of school-based dramatherapy for children and young people with emotional distress

Dramatherapy, a creative form of psychotherapy, is used as a treatment for children and young people (CYPs) who have common mental disorders including anxiety, depression and trauma. Although widely used, particularly in schools, little is known about the active ingredients of this intervention. A qualitative approach, triangulating both semi-structured interviews (N = 11) and a focus group (N = 5), was taken to elicit dramatherapists’ perspectives on the active ingredients of school-based dramatherapy. 11 active ingredients were identified. That dramatherapy fosters autonomy, freedom and agency (1), that experiences are processed creatively (2), that CYPs experience and express emotions (3) in dramatherapy, were found; dramatherapy’s person-centredness (4) and the use of structure (5) were also found. The creation of safety, in the therapeutic relationship (6) and space (7) and, the ability to develop meaningful social connections (8) via dramatherapy, were also identified as active ingredients, as were, dramatherapists’ use of theory (9), the importance of a systemic approach (10) and that therapeutic experiences are integrated into life beyond dramatherapy (11). This study is the first to explore the active ingredients of school-based dramatherapy for CYPs with emotional distress. The findings presented may inform further research, measuring mediators of change, and practice, which enhances symptom reduction

Harmonic analysis of iterated function systems with overlap

In this paper we extend previous work on IFSs without overlap. Our method involves systems of operators generalizing the more familiar Cuntz relations from operator algebra theory, and from subband filter operators in signal processing.Comment: 37 page

Excitation spectrum in a cylindrical Bose-Einstein gas

Whole excitation spectrum is calculated within the Popov approximation of the Bogoliubov theory for a cylindrical symmetric Bose-Einstein gas trapped radially by a harmonic potential. The full dispersion relation and its temperature dependence of the zero sound mode propagating along the axial direction are evaluated in a self-consistent manner. The sound velocity is shown to depend not only on the peak density, but also on the axial area density. Recent sound velocity experiment on Na atom gas is discussed in light of the present theory.Comment: 4 pages, 5 eps figure