A dimension-breaking phenomenon for water waves with weak surface tension

It is well known that the water-wave problem with weak surface tension has small-amplitude line solitary-wave solutions which to leading order are described by the nonlinear Schr\"odinger equation. The present paper contains an existence theory for three-dimensional periodically modulated solitary-wave solutions which have a solitary-wave profile in the direction of propagation and are periodic in the transverse direction; they emanate from the line solitary waves in a dimension-breaking bifurcation. In addition, it is shown that the line solitary waves are linearly unstable to long-wavelength transverse perturbations. The key to these results is a formulation of the water wave problem as an evolutionary system in which the transverse horizontal variable plays the role of time, a careful study of the purely imaginary spectrum of the operator obtained by linearising the evolutionary system at a line solitary wave, and an application of an infinite-dimensional version of the classical Lyapunov centre theorem.Comment: The final publication is available at Springer via http://dx.doi.org/10.1007/s00205-015-0941-

Deep swarm: Nested particle swarm optimization

A new generation of particle swarm optimization (PSO) has been developed that automatically evolves optimal or near-optimal values for parameters of the PSO algorithm such as population size and neighborhood size, and, if used, parameters of associated neural network(s), such as number of hidden processing elements (PEs). Called Deep Swarm, it is a nested version of PSO, and comprises swarms within a swarm

Supporting home care for the dying: an evaluation of healthcare professionals' perspectives of an individually tailored hospice at home service

AIMS AND OBJECTIVES: To explore health care professionals' perspective of hospice at home service that has different components, individually tailored to meet the needs of patients. BACKGROUND: Over 50% of adults diagnosed with a terminal illness and the majority of people who have cancer, prefer to be cared for and to die in their own home. Despite this, most deaths occur in hospital. Increasing the options available for patients, including their place of care and death is central to current UK policy initiatives. Hospice at home services aim to support patients to remain at home, yet there are wide variations in the design of services and delivery. A hospice at home service was developed to provide various components (accompanied transfer home, crisis intervention and hospice aides) that could be tailored to meet the individual needs of patients. DESIGN: An evaluation study. METHODS: Data were collected from 75 health care professionals. District nurses participated in one focus group (13) and 31 completed an electronic survey. Palliative care specialist nurses participated in a focus group (9). One hospital discharge co-ordinator and two general practitioners participated in semi-structured interviews and a further 19 general practitioners completed the electronic survey. RESULTS: Health care professionals reported the impact and value of each of the components of the service, as helping to support patients to remain at home, by individually tailoring care. They also positively reported that support for family carers appeared to enable them to continue coping, rapid access to the service was suggested to contribute to faster hospital discharges and the crisis intervention service was identified as helping patients remain in their own home, where they wanted to be. CONCLUSIONS: Health care professionals perceived that the additional individualised support provided by this service contributed to enabling patients to continue be cared for and to die at home in their place of choice. RELEVANCE TO CLINICAL PRACTICE: This service offers various components of a hospice at home service, enabling a tailor made package to meet individual and local area needs. Developing an individually tailored package of care appears to be able to meet specific needs

Culture in Reduced Levels of Oxygen Promotes Clonogenic Sympathoadrenal Differentiation by Isolated Neural Crest Stem Cells

Isolated neural crest stem cells (NCSCs) differentiate to autonomic neurons in response to bone morphogenetic protein 2 (BMP2) in clonal cultures, but these neurons do not express sympathoadrenal (SA) lineage markers. Whether this reflects a developmental restriction in NCSCs or simply inappropriate culture conditions was not clear. We tested the growth and differentiation potential of NCSCs at ∼5% O_2, which more closely approximates physiological oxygen levels. Eighty-three percent of p75^+P_0 ^− cells isolated from embryonic day 14.5 sciatic nerve behaved as stem cells under these conditions, suggesting that this is a nearly pure population. Furthermore, addition of BMP2 plus forskolin in decreased oxygen cultures elicited differentiation of thousands of cells expressing tyrosine hydroxylase, dopamine-β-hydroxylase, and the SA lineage marker SA-1 in nearly all colonies. Such cells also synthesized and released dopamine and norepinephrine. These data demonstrate that isolated mammalian NCSCs uniformly possess SA lineage capacity and further suggest that oxygen levels can influence cell fate. Parallel results indicating that reduced oxygen levels can also promote the survival, proliferation, and catecholaminergic differentiation of CNS stem cells (Studer et al., 2000) suggests that neural stem cells may exhibit a conserved response to reduced oxygen levels

The Contribution of the Pineal Gland on Daily Rhythms and Masking in Diurnal Grass Rats, Arvicanthis niloticus

Melatonin is a hormone rhythmically secreted at night by the pineal gland in vertebrates. In diurnal mammals, melatonin is present during the inactive phase of the rest/activity cycle, and in primates it directly facilitates sleep and decreases body temperature. However, the role of the pineal gland for the promotion of sleep at night has not yet been studied in non-primate diurnal mammalian species. Here, the authors directly examined the hypothesis that the pineal gland contributes to diurnality in Nile grass rats by decreasing activity and increasing sleep at night, and that this could occur via effects on circadian mechanisms or masking, or both. Removing the pineal gland had no effect on the hourly distribution of activity across a 12:12 light-dark (LD) cycle or on the patterns of sleep-like behavior at night. Masking effects of light at night on activity were also not significantly different in pinealectomized and control grass rats, as 1h pulses of light stimulated increases in activity of sham and pinealectomized animals to a similar extent. In addition, the circadian regulation of activity was unaffected by the surgical condition of the animals. Our results suggest that the pineal gland does not contribute to diurnality in the grass rat, thus highlighting the complexity of temporal niche transitions. The current data raise interesting questions about how and why genetic and neural mechanisms linking melatonin to sleep regulatory systems might vary among mammals that reached a diurnal niche via parallel and independent pathways

Respiratory Motion Correction in Dynamic PET with a Single Attenuation Map

In addition to static tracer uptake values used routinely in clinical facilities, PET imaging can provide useful information on tracer kinetics via the use of dynamic acquisitions where a set of time frames are acquired starting from the injection/inhalation of the radiotracer. In lung studies, kinetic parameters, estimated from compartmental modelling, are however affected by respiratory motion. When only one attenuation image is available, most existing motion compensation strategies are not appropriate for the initial short time frames, especially as the activity distribution changes rapidly over the early part of the dynamic acquisition. This work presents a preliminary study to handle respiratory motion using a two-step process that uses gated dynamic data as input. We first use joint reconstruction of activity and motion on the entire gated PET data to estimate deformation fields. This allows the subsequent reconstruction of each time frame separately with motion compensation. We present results comparing on one hand the compartment model fit residuals with and without respiratory motion compensation and on the other hand the diaphragm position in non-attenuation corrected images and from this method

A Reciprocal Cell–Cell Interaction Mediated by NT-3 and Neuregulins Controls the Early Survival and Development of Sympathetic Neuroblasts

Neurotrophin 3 (NT-3) can support the survival of some embryonic sympathetic neuroblasts before they become nerve growth factor dependent. We show that NT-3 is produced in vivo by nonneuronal cells neighboring embryonic sympathetic ganglia. NT-3 mRNA is produced by these nonneuronal cells in vitro and is up-regulated by platelet-derived growth factor, ciliary neurotrophic factor, and glial growth factor 2 (a neuregulin). Nonneuronal cell–conditioned medium promotes survival and induces TrkA expression in isolated sympathetic neuroblasts, and this activity is blocked by anti-NT-3 antibody. Neuroblasts also enhance NT-3 production by nonneuronal cells. Neuroblasts synthesize several forms of neuregulin, and antibodies to neuregulin attenuate the effect of the neuroblasts on the nonneuronal cells. These data suggest a reciprocal cell–cell interaction, in which neuroblast-derived neuregulins promote NT-3 production by neighboring nonneuronal cells, which in turn promotes neuroblast survival and further differentiation