Seed germination and in vitro regeneration of the African medicinal and pesticidal plant, Bobgunnia madagascariensis

Propagation of the medicinal and pesticidal tree, Bobgunnia madagascarensis is difficult due to poor and erratic germination of its seeds and slow growth of its seedlings. This study involved two separate experiments. The first evaluated the effect of pre-sowing treatments and growing medium on ex vitro seed germination and early seedling development. The second experiment involved in vitro germination, shoot initiation and rooting of shoots. Pre-sowing seed treatments involved soaking seeds in cold and hot water for 12 and 24 h and soaking in different concentrations (0, 100, 200, 400 and 800 mg/l) of gibberellic acid for 24 h. Soaking of seeds in cold or hot water for up to 24 h did not achieve more than 45% germination, while seeds treated with gibberellic acid achieved <20% germination rates. On the other hand, in vitro procedures achieved 30 to 70% germination of seeds. Seedling survival of ex-vitro germinated seeds was higher (>76%) when seeds were sown in a growing medium without compost compared with a medium with compost (<43%). All shoot-tips isolated from the in vitro germinated seedlings on B5 media without plant growth regulators continued to grow as a single shoot, while shoot-tips cultured on B5 supplemented with 0.1 mg/l of naphthaleneacetic acid (NAA) and thidiazuron (TDZ) produced two shoots each after four weeks. It was concluded that B. madagascariensis seeds had very low ex vitro germination percentages. Although, in vitro cultures improved seed germination, axillary shoot multiplication and rooting were not satisfactory. Therefore, further studies are needed to develop an optimal in vitro multiplication protocol for B. madagascariensis.Key words: Axillary shoot multiplication, gibberellic acid, in vitro regeneration, seed germination, Swartzia

Quantum-fluid dynamics of microcavity polaritons

Semiconductor microcavities offer a unique system to investigate the physics of weakly interacting bosons. Their elementary excitations, polaritons--a mixture of excitons and photons--behave, in the low density limit, as bosons that can undergo a phase transition to a regime characterised by long range coherence. Condensates of polaritons have been advocated as candidates for superfluidity; and the formation of vortices as well as elementary excitations with a linear dispersion are actively sought after. In this work, we have created and set in motion a macroscopically degenerate state of polaritons and let it collide with a variety of defects present in the sample. Our experiments show striking manifestations of a coherent light-matter packet that displays features of a superfluid, although one of a highly unusual character as it involves an out-of-equilibrium dissipative system where it travels at ultra-fast velocity of the order of 1% the speed of light. Our main results are the observation of i) a linear polariton dispersion accompanied with diffusion-less motion, ii) flow without resistance when crossing an obstacle, iii) suppression of Rayleigh scattering and iv) splitting into two fluids when the size of the obstacle is comparable with the size of the wavepacket. This work opens the way to the investigation of new phenomenology of out-of-equilibrium condensates.Comment: 22 pages, 5 figure

Adherence to the Eatwell Guide and cardiometabolic, cognitive and neuroimaging parameters: an analysis from the PREVENT dementia study

BackgroundThe Eatwell guide reflects the UK government\u27s recommendations for a healthy and balanced diet. Previous research has identified associations between healthy eating patterns and both cardiovascular and brain health, although there is little evidence specifically focusing on the Eatwell Guide. To date no research has investigated associations between the Eatwell Guide and risk for future dementia.MethodsData from the PREVENT dementia cohort study baseline visit was used in this analysis. Binary and graded Eatwell Guide scores (BEWG, GEWG) were created from a self-reported Food Frequency Questionnaire. The CAIDE score was included as the primary outcome measure to represent risk for future Alzheimer’s disease. Secondary outcome measures included cardiometabolic health measures and brain health measures. Generalised additive models were run in R.ResultsA total of 517 participants were included in the analysis, with a mean BEWG score of 4.39 (\ub1 1.66) (out of a possible 12 points) and GEWG score of 39.88 (\ub1 6.19) (out of a possible 60 points). There was no significant association between either Eatwell Guide score and the CAIDE score (BEWG β: 0.07, 95% confidence interval (CI): -0.07, 0.22; GEWG β: 0.02, 95% CI: -0.02, 0.06) or any measures of brain health. There was a significant association between higher GEWG score and lower systolic and diastolic blood pressure and body mass index (BMI) (systolic β: -0.24, 95% CI: -0.45, -0.03; diastolic β: -0.16, 95% CI: -0.29, -0.03; BMI β: -0.09, 95% CI: -0.16, -0.01).ConclusionsAlthough not directly associated with the CAIDE score, the Eatwell Guide dietary pattern may be beneficial for dementia prevention efforts through the modification of hypertension and obesity, which are both known risk factors for dementia. Future work could replicate these findings in other UK-based cohorts as well as further development of Eatwell Guide scoring methodologies

Odour-mediated orientation of beetles is influenced by age, sex and morph

The behaviour of insects is dictated by a combination of factors and may vary considerably between individuals, but small insects are often considered en masse and thus these differences can be overlooked. For example, the cowpea bruchid Callosobruchus maculatus F. exists naturally in two adult forms: the active (flight) form for dispersal, and the inactive (flightless), more fecund but shorter-lived form. Given that these morphs show dissimilar biology, it is possible that they differ in odour-mediated orientation and yet studies of this species frequently neglect to distinguish morph type, or are carried out only on the inactive morph. Along with sex and age of individual, adult morph could be an important variable determining the biology of this and similar species, informing studies on evolution, ecology and pest management. We used an olfactometer with motion-tracking to investigate whether the olfactory behaviour and orientation of C. maculatus towards infested and uninfested cowpeas and a plant-derived repellent compound, methyl salicylate, differed between morphs or sexes. We found significant differences between the behaviour of male and female beetles and beetles of different ages, as well as interactive effects of sex, morph and age, in response to both host and repellent odours. This study demonstrates that behavioural experiments on insects should control for sex and age, while also considering differences between adult morphs where present in insect species. This finding has broad implications for fundamental entomological research, particularly when exploring the relationships between physiology, behaviour and evolutionary biology, and the application of crop protection strategies

Disorder Effects on Exciton-Polariton Condensates

The impact of a random disorder potential on the dynamical properties of Bose Einstein condensates is a very wide research field. In microcavities, these studies are even more crucial than in the condensates of cold atoms, since random disorder is naturally present in the semiconductor structures. In this chapter, we consider a stable condensate, defined by a chemical potential, propagating in a random disorder potential, like a liquid flowing through a capillary. We analyze the interplay between the kinetic energy, the localization energy, and the interaction between particles in 1D and 2D polariton condensates. The finite life time of polaritons is taken into account as well. In the first part, we remind the results of [G. Malpuech et al. Phys. Rev. Lett. 98, 206402 (2007).] where we considered the case of a static condensate. In that case, the condensate forms either a glassy insulating phase at low polariton density (strong localization), or a superfluid phase above the percolation threshold. We also show the calculation of the first order spatial coherence of the condensate versus the condensate density. In the second part, we consider the case of a propagating non-interacting condensate which is always localized because of Anderson localization. The localization length is calculated in the Born approximation. The impact of the finite polariton life time is taken into account as well. In the last section we consider the case of a propagating interacting condensate where the three regimes of strong localization, Anderson localization, and superfluid behavior are accessible. The localization length is calculated versus the system parameters. The localization length is strongly modified with respect to the non-interacting case. It is infinite in the superfluid regime whereas it is strongly reduced if the fluid flows with a supersonic velocity.Comment: chapter for a book "Exciton Polaritons in Microcavities: New Frontiers" by Springer (2012), the original publication is available at http://www.springerlink.co

Clinical decision-making: physicians' preferences and experiences

BACKGROUND: Shared decision-making has been advocated; however there are relatively few studies on physician preferences for, and experiences of, different styles of clinical decision-making as most research has focused on patient preferences and experiences. The objectives of this study were to determine 1) physician preferences for different styles of clinical decision-making; 2) styles of clinical decision-making physicians perceive themselves as practicing; and 3) the congruence between preferred and perceived style. In addition we sought to determine physician perceptions of the availability of time in visits, and their role in encouraging patients to look for health information. METHODS: Cross-sectional survey of a nationally representative sample of U.S. physicians. RESULTS: 1,050 (53% response rate) physicians responded to the survey. Of these, 780 (75%) preferred to share decision-making with their patients, 142 (14%) preferred paternalism, and 118 (11%) preferred consumerism. 87% of physicians perceived themselves as practicing their preferred style. Physicians who preferred their patients to play an active role in decision-making were more likely to report encouraging patients to look for information, and to report having enough time in visits. CONCLUSION: Physicians tend to perceive themselves as practicing their preferred role in clinical decision-making. The direction of the association cannot be inferred from these data; however, we suggest that interventions aimed at promoting shared decision-making need to target physicians as well as patients

Epstein-Barr Virus Associated Modulation of Wnt Pathway Is Not Dependent on Latent Membrane Protein-1

Previous studies have indicated that Epstein-Barr virus (EBV) can modulate the Wnt pathway in virus-infected cells and this effect is mediated by EBV-encoded oncogene latent membrane protein 1 (LMP1). Here we have reassessed the role of LMP1 in regulating the expression of various mediators of the canonical Wnt cascade. Contradicting the previous finding, we found that the levels of E-cadherin, β-catenin, Glycogen Synthase Kinase 3ß (GSK3β), axin and α-catenin were not affected by the expression of LMP1 sequences from normal B cells or nasopharyngeal carcinoma. Moreover, we also show that LMP1 expression had no detectable effect on the E-cadherin and β-catenin interaction and did not induce transcriptional activation of β-catenin. Taken together these studies demonstrate that EBV-mediated activation of Wnt pathway is not dependent on the expression of LMP1

Genome-Wide Analysis of the Emerging Infection with Mycobacterium avium Subspecies paratuberculosis in the Arabian Camels (Camelus dromedarius)

Mycobacterium avium subspecies paratuberculosis (M. ap) is the causative agent of paratuberculosis or Johne's disease (JD) in herbivores with potential involvement in cases of Crohn's disease in humans. JD is spread worldwide and is economically important for both beef and dairy industries. Generally, pathogenic ovine strains (M. ap-S) are mainly found in sheep while bovine strains (M. ap-C) infect other ruminants (e.g. cattle, goat, deer), as well as sheep. In an effort to characterize this emerging infection in dromedary/Arabian camels, we successfully cultured M. ap from several samples collected from infected camels suffering from chronic, intermittent diarrhea suggestive of JD. Gene-based typing of isolates indicated that all isolates belong to sheep lineage of strains of M. ap (M. ap-S), suggesting a putative transmission from infected sheep herds. Screening sheep and goat herds associated with camels identified the circulation of this type in sheep but not goats. The current genome-wide analysis recognizes these camel isolates as a sub-lineage of the sheep strain with a significant number of single nucleotide polymorphisms (SNPs) between sheep and camel isolates (∼1000 SNPs). Such polymorphism could represent geographical differences among isolates or host adaptation of M. ap during camel infection. To our knowledge, this is the first attempt to examine the genomic basis of this emerging infection in camels with implications on the evolution of this important pathogen. The sequenced genomes of M. ap isolates from camels will further assist our efforts to understand JD pathogenesis and the dynamic of disease transmission across animal species

Dynamics of carbon pools in post-agrogenic sandy soils of southern taiga of Russia

<p>Abstract</p> <p>Background</p> <p>Until recently, a lot of arable lands were abandoned in many countries of the world and, especially, in Russia, where about half a million square kilometers of arable lands were abandoned in 1961-2007. The soils at these fallows undergo a process of natural restoration (or self-restoration) that changes the balance of soil organic matter (SOM) supply and mineralization.</p> <p>Results</p> <p>A soil chronosequence study, covering the ecosystems of 3, 20, 55, 100, and 170 years of self-restoration in southern taiga zone, shows that soil organic content of mineral horizons remains relatively stable during the self-restoration. This does not imply, however, that SOM pools remain steady. The C/N ratio of active SOM reached steady state after 55 years, and increased doubly (from 12.5 - 15.6 to 32.2-33.8). As to the C/N ratio of passive SOM, it has been continuously increasing (from 11.8-12.7 to 19.0-22.8) over the 170 years, and did not reach a steady condition.</p> <p>Conclusion</p> <p>The results of the study imply that soil recovery at the abandoned arable sandy lands of taiga is incredibly slow process. Not only soil morphological features of a former ploughing remained detectable but also the balance of soil organic matter input and mineralization remained unsteady after 170 years of self-restoration.</p

A life course approach to injury prevention: a "lens and telescope" conceptual model

<p>Abstract</p> <p>Background</p> <p>Although life course epidemiology is increasingly employed to conceptualize the determinants of health, the implications of this approach for strategies to reduce the burden of injuries have received little recognition to date.</p> <p>Methods</p> <p>The authors reviewed core injury concepts and the principles of the life course approach. Based on this understanding, a conceptual model was developed, to provide a holistic view of the mechanisms that underlie the accumulation of injury risk and their consequences over the life course.</p> <p>Results</p> <p>A "lens and telescope" model is proposed that particularly draws on (a) the extended temporal dimension inherent in the life course approach, with links between exposures and outcomes that span many years, or even generations, and (b) an ecological perspective, according to which the contexts in which individuals live are critical, as are changes in those contexts over time.</p> <p>Conclusions</p> <p>By explicitly examining longer-term, intergenerational and ecological perspectives, life course concepts can inform and strengthen traditional approaches to injury prevention and control that have a strong focus on proximal factors. The model proposed also serves as a tool to identify intervention strategies that have co-benefits for other areas of health.</p