The evolutionary sequence of active galactic nuclei and galaxy formation revealed

Today, almost every galaxy spheroid contains a massive black hole: a remnant of, and testament to, a period in its evolution when it contained an active galactic nucleus (AGN). However, the sequence and timescales of the formation of the black hole and surrounding spheroid of stars are completely unknown, leaving a large gap in our knowledge of how the universe attained its present appearance. Here we present submillimeter observations of matched samples of X-ray absorbed and unabsorbed AGNs that have luminosities and redshifts characteristic of the sources responsible for most of the mass in present-day black holes. Strong submillimeter emission, an isotropic signature of copious star formation, is found only in the X-ray–absorbed sample, ruling out orientation effects as the cause of the absorption. The space density and luminosity range of the X-ray–absorbed AGNs indicate that they are undergoing the transition between a hidden growth phase and an unabsorbed AGN phase and imply that the X-ray–absorbed period in the AGN's evolution coincides with the formation of the galaxy spheroid

Comparative biology of different plant pathogens to estimate effects of climate change on crop diseases in Europe

This review describes environmental factors that influence severity of crop disease epidemics, especially in the UK and north-west Europe, in order to assess the effects of climate change on crop growth and yield and severity of disease epidemics. While work on some diseases, such as phoma stem canker of oilseed rape and fusarium ear blight of wheat, that combine crop growth, disease development and climate change models is described in detail, climate-change projections and predictions of the resulting biotic responses to them are complex to predict and detailed models linking climate, crop growth and disease development are not available for many crop-pathogen systems. This review uses a novel approach of comparing pathogen biology according to 'ecotype' (a categorization based on aspects such as epidemic type, dissemination method and infection biology), guided by detailed disease progress models where available to identify potential future research priorities for disease control. Consequences of projected climate change are assessed for factors driving elements of disease cycles of fungal pathogens (nine important pathogens are assessed in detail), viruses, bacteria and phytoplasmas. Other diseases classified according to 'ecotypes' were reviewed and likely changes in their severity used to guide comparable diseases about which less information is available. Both direct and indirect effects of climate change are discussed, with an emphasis on examples from the UK, and considered in the context of other factors that influence diseases and particularly emergence of new diseases, such as changes to farm practices and introductions of exotic material and effects of other environment changes such as elevated CO 2. Good crop disease control will contribute to climate change mitigation by decreasing greenhouse gas emissions from agriculture while sustaining production. Strategies for adaptation to climate change are needed to maintain disease control and crop yields in north-west Europe.Peer reviewe

The twin paradox in compact spaces

Twins travelling at constant relative velocity will each see the other's time dilate leading to the apparent paradox that each twin believes the other ages more slowly. In a finite space, the twins can both be on inertial, periodic orbits so that they have the opportunity to compare their ages when their paths cross. As we show, they will agree on their respective ages and avoid the paradox. The resolution relies on the selection of a preferred frame singled out by the topology of the space.Comment: to be published in PRA, 3 page

Role of bacterial isolates in enhancing the bud induction in the industrially important red alga Gracilaria dura

Plant growth depends on the integration of environmental cues, nitrogen fixation and phytohormone-signaling pathways. The growth and development of Gracilaria dura was significantly influenced by the association of bacterial isolates. The putative bud-inducing epiphytic Exiguobacterium homiense and endophytic Bacillus pumilus, Bacillus licheniformis were examined for their ability to fix nitrogen and produce indole-3-acetic acid (IAA). These bacterial isolates were identified to the species level by biochemical tests, fatty acid and partial 16S rRNA gene sequence analysis. The B. pumilus, B. licheniformis and E. homiense produced 445.5, 335 and 184.1 μg mL−1 IAA and 12.51, 10.14 and 6.9 mM mL−1 ammonium, respectively, as determined using HPLC and spectroscopy. New bud regeneration observed after the addition of total protein of the bacterial isolates suggests that IAA is conjugated with protein. The epi- and endophytic bacterial isolates were able to induce five and 10 new buds per frond, respectively, in comparison to the control, where one to two buds were observed. The combination of 25 °C and 30‰ showed the optimum condition for bud induction in G. dura when incubated with the total protein of B. pumilus. Our finding revealed for the first time that IAA coupled with nitrogen fixation induce and regenerate new buds in G. dur

Construction and characterization of Enterococcus faecalis CG110/gfp/pRE25*, a tool for monitoring horizontal gene transfer in complex microbial ecosystems

Enterococci are among the most notorious bacteria involved in the spread of antibiotic resistance (ABR) determinants via horizontal gene transfer, a process that leads to increased prevalence of antibiotic-resistant bacteria. In complex microbial communities with a high background of ABR genes, detection of gene transfer is possible only when the ABR determinant is marked. Therefore, the conjugative multiresistance plasmid pRE25, originating from a sausage-associated Enterococcus faecalis, was tagged with a 34-bp random sequence marker spliced by tet(M). The plasmid constructed, designated pRE25*, was introduced into E. faecalis CG110/gfp, a strain containing a gfp gene as chromosomal marker. The plasmid pRE25* is fully functional compared with its parental pRE25, occurs at one to two copies per chromosome, and can be transferred to Listeria monocytogenes and Listeria innocua at frequencies of 6 × 10−6 to 8 × 10−8 transconjugants per donor. The markers on the chromosome and the plasmid enable independent quantification of donor and plasmid, even if ABR genes occur at high numbers in the background ecosystem. Both markers were stable for at least 200 generations, permitting application of the strain in long-running experiments. Enterococcus faecalis CG110/gfp/pRE25* is a potent tool for the investigation of horizontal ABR gene transfer in complex environments such as food matrices, biofilms or colonic model

Ultra-fast propagation of Schr\"odinger waves in absorbing media

We identify the characteristic times of the evolution of a quantum wave generated by a point source with a sharp onset in an absorbing medium. The "traversal'' or "B\"uttiker-Landauer'' time (which grows linearly with the distance to the source) for the Hermitian, non-absorbing case is substituted by three different characteristic quantities. One of them describes the arrival of a maximum of the density calculated with respect to position, but the maximum with respect to time for a given position becomes independent of the distance to the source and is given by the particle's ``survival time'' in the medium. This later effect, unlike the Hartman effect, occurs for injection frequencies under or above the cut-off, and for arbitrarily large distances. A possible physical realization is proposed by illuminating a two-level atom with a detuned laser

Search for the hero: an investigation into the sports heroes of British sports fans

This is an initial study into British sports fans’ heroes. A questionnaire was sent to 95 students (average age ¼ 19.75) to identify their sporting hero, the hero’s sport and nationality and the reasons for this choice. Football was the most common source of sports heroes, identified by 49% of participants with a sporting hero. The majority (60%, N ¼ 48) of heroes chosen by participants were British, with David Beckham the most popular choice. Differences were observed between the gender of participants, gender of hero chosen and the reasons for choosing the hero. The most common reason for selecting a hero was a personal trait rather than skill, while in the questionnaire a category of Local Affiliation was added to those suggested by previous work. It was concluded that to become a hero athletes should combine skill with devotion to family, charity work and a place in popular culture

Relationship between tinnitus pitch and edge of hearing loss in individuals with a narrow tinnitus bandwidth

Objective: Psychoacoustic measures of tinnitus, in particular dominant tinnitus pitch and its relationship to the shape of the audiogram, are important in determining and verifying pathophysiological mechanisms of the condition. Our previous study postulated that this relationship might vary between different groups of people with tinnitus. For a small subset of participants with narrow tinnitus bandwidth, pitch was associated with the audiometric edge, consistent with the tonotopic reorganization theory. The current study objective was to establish this relationship in an independent sample. Design: This was a retrospective design using data from five studies conducted between 2008 and 2013. Study sample: From a cohort of 380 participants, a subgroup group of 129 with narrow tinnitus bandwidth were selected. Results: Tinnitus pitch generally fell within the area of hearing loss. There was a statistically significant correlation between dominant tinnitus pitch and edge frequency; higher edge frequency being associated with higher dominant tinnitus pitch. However, similar to our previous study, for the majority of participants pitch was more than an octave above the edge frequency. Conclusions: The findings did not support our prediction and are therefore not consistent with the reorganization theory postulating tinnitus pitch to correspond to the audiometric edge