Switching model with two habitats and a predator involving group defence

Switching model with one predator and two prey species is considered. The prey species have the ability of group defence. Therefore, the predator will be attracted towards that habitat where prey are less in number. The stability analysis is carried out for two equilibrium values. The theoretical results are compared with the numerical results for a set of values. The Hopf bifuracation analysis is done to support the stability results

Lambda^0 polarization as a probe for production of deconfined matter in ultra-relativistic heavy-ion collisions

We study the polarization change of Lambda^0's produced in ultra-relativistic heavy-ion collisions with respect to the polarization observed in proton-proton collisions as a signal for the formation of a Quark-Gluon Plasma (QGP). Assuming that, when the density of participants in the collision is larger than the critical density for QGP formation, the Lambda^0 production mechanism changes from recombination type processes to the coalescence of free valence quarks, we find that the Lambda^0 polarization depends on the relative contribution of each process to the total number of Lambda^0's produced in the collision. To describe the polarization of Lambda^0's in nuclear collisions for densities below the critical density for the QGP formation, we use the DeGrand-Miettinen model corrected for the effects introduced by multiple scattering of the produced Lambda^0 within the nuclear environment.Comment: 9 pages, 6 figures, uses ReVTeX and epsfig.st

A review of diagnostic and functional imaging in headache

The neuroimaging of headache patients has revolutionised our understanding of the pathophysiology of primary headaches and provided unique insights into these syndromes. Modern imaging studies point, together with the clinical picture, towards a central triggering cause. The early functional imaging work using positron emission tomography shed light on the genesis of some syndromes, and has recently been refined, implying that the observed activation in migraine (brainstem) and in several trigeminal-autonomic headaches (hypothalamic grey) is involved in the pain process in either a permissive or triggering manner rather than simply as a response to first-division nociception per se. Using the advanced method of voxel-based morphometry, it has been suggested that there is a correlation between the brain area activated specifically in acute cluster headache — the posterior hypothalamic grey matter — and an increase in grey matter in the same region. No structural changes have been found for migraine and medication overuse headache, whereas patients with chronic tension-type headache demonstrated a significant grey matter decrease in regions known to be involved in pain processing. Modern neuroimaging thus clearly suggests that most primary headache syndromes are predominantly driven from the brain, activating the trigeminovascular reflex and needing therapeutics that act on both sides: centrally and peripherally

Computing gravitational waves from slightly nonspherical stellar collapse to black hole: Odd-parity perturbation

Nonspherical stellar collapse to a black hole is one of the most promising gravitational wave sources for gravitational wave detectors. We numerically study gravitational waves from a slightly nonspherical stellar collapse to a black hole in linearized Einstein theory. We adopt a spherically collapsing star as the zeroth-order solution and gravitational waves are computed using perturbation theory on the spherical background. In this paper we focus on the perturbation of odd-parity modes. Using the polytropic equations of state with polytropic indices $n_p=1$ and 3, we qualitatively study gravitational waves emitted during the collapse of neutron stars and supermassive stars to black holes from a marginally stable equilibrium configuration. Since the matter perturbation profiles can be chosen arbitrarily, we provide a few types for them. For $n_p=1$, the gravitational waveforms are mainly characterized by a black hole quasinormal mode ringing, irrespective of perturbation profiles given initially. However, for $n_p=3$, the waveforms depend strongly on the initial perturbation profiles. In other words, the gravitational waveforms strongly depend on the stellar configuration and, in turn, on the ad hoc choice of the functional form of the perturbation in the case of supermassive stars.Comment: 31 pages, accepted for publication in Phys. Rev. D, typos and minor errors correcte

Evolution of HCl Concentrations in the Lower Stratosphere from 1991 to 1996 Following the Eruption of Mt. Pinatubo

Geophysical Research Letters, Vol. 25, No. 7, pp. 995-998, April 1, 1998.In situ measurements of hydrochloric acid in the lower stratosphere reveal that its mean abundance relative to that of total inorganic chlorine..

(New) Bulgarian Enlighteners and Ambassadors? The Reinvention of National Identity in Times of Crisis

Drawing on empirical data from 37 Bulgarian students and young professionals in the UK, this article explores the intersection of the discourses produced by the European crises and migrants' national identity. In Bulgaria, the crisis narrative is embedded in the arguably never‐ending democratic transition, manifested in socio‐economic instability and political volatility. Simultaneously, “Brexit Britain” is enveloped in strong Eurosceptic sentiments, propelled by a combination of austerity measures and intensified Eastern European migratory flows. Both contexts subject Bulgarian migrants to stigmatizing representations. Looking at migrants' everyday practices, the data reveals that young Bulgarians draw on the related ideas of the “new” Enlightener and Ambassador to counterbalance negative discourses. Thus, the article explores the meanings and significance attributed to the Enlighteners and the Ambassadors, arguing that the participants engage in “social creativity” and “individual mobility” strategies that lead to reinvention of national identity

Impact of mode of conception on neonatal and neurodevelopmental outcomes in preterm infants

STUDY QUESTION: Is assisted conception associated with neonatal morbidity and mortality and with neurodevelopmental impairment at 2 years of corrected age in preterm infants born before 34 weeks of gestational age? SUMMARY ANSWER: Assisted conception is not associated with an increase in neonatal morbidity and mortality and is even significantly associated with a better 2-year neurodevelopmental outcome in preterm infants. WHAT IS KNOWN ALREADY: Assisted conception appears to increase the rate of preterm births, though few studies have analysed outcomes for these preterm infants. STUDY DESIGN, SIZE, DURATION: This prospective observational study included 703 preterm infants born between January 2009 and December 2013 and 573 of them were assessed at 2 years of corrected age. PARTICIPANTS/MATERIALS, SETTING, METHODS: All infants born alive between 24+0 and 33+6 weeks of gestational age and hospitalised at the Angers University Hospital were eligible as long as the mode of conception was known for neonatal outcome assessment. They were enroled in the Loire Infant Follow-up Team (LIFT) prospective longitudinal cohort and included for neurodevelopmental outcome assessment. Neonatal morbidity and mortality were evaluated during hospitalisation based on a composite score including death, intraventricular haemorrhage Grade ≥3, periventricular leukomalacia, treated patent ductus arteriosus and bronchopulmonary dysplasia at 36 weeks of gestational age. The neurodevelopmental outcome at 2 years of corrected age was determined by a physical examination, a neuropsychological test and a parental questionnaire. In order to ensure comparability, infants were matched 1:1 according to maternal age, twin status and propensity score,calculated from variables usually associated (positively or negatively) with assisted conception, including gestational age, z-score of birth weight, antenatal corticosteroids and magnesium sulphate treatments, gender, parity, maternal body mass index, tobacco consumption, outborn delivery (i.e. not at a tertiary-care medical centre) and maternal socio-economic status. MAIN RESULTS AND THE ROLE OF CHANCE: There were 703 preterm infants included in the analysis of neonatal morbidity and mortality, including 137 born after assisted conception. After matching, 184 preterm infants were included for neonatal morbidity and mortality analysis. There was no significant association between assisted conception and neonatal morbidity and mortality (aOR 0.67, 95% CI [0.25, 1.77], P = 0.422). 573 infants were assessed at 2 years, including 121 born after assisted conception. After matching, 154 preterm infants were included for neurodevelopmental outcome analysis. Assisted conception was significantly associated with a reduction in the probability of non-optimal neurological development at 2 years (aOR 0.26, 95% CI [0.09, 0.80], P = 0.019). LIMITATION, REASONS FOR CAUTION: Further studies remain necessary to fully confirm these results. This was a monocentric study and 14% of enroled infants were lost to follow up at 2 years of corrected age. WIDER IMPLICATIONS OF THE FINDINGS: These findings are relevant for providing appropriate information to parents considering assisted conception, and more importantly for those with a preterm infant following a pregnancy achieved by assisted conception. STUDY FUNDING/COMPETING INTEREST(S): The authors report external funding and no conflicts of interest for this work. TRIAL REGISTRATION NUMBER: N/A