328 research outputs found
A role for the asexual spores in infection of Fraxinus excelsior by the ash-dieback fungus Hymenoscyphus fraxineus
This is the final version of the article. Available from Springer Nature via the DOI in this record.There is another ORE record for this article: http://hdl.handle.net/10871/23613The invasive pathogen, ash dieback fungus Hymenoscyphus fraxineus, is spreading rapidly across
Europe. It shows high levels of outcrossing and limited population structure, even at the epidemic front. The anamorphic (asexual) form produces prolific conidia, thought to function solely as spermatia (malegametes), facilitating gene flow between sympatric strains. Here, we show that conidia are capable of germination on ash leaves and in vitro, and can infect seedlings via leaves or soil. In leaves, germlings form structures resembling fruiting bodies. Additionally, H. fraxineus colonises ash debris and grows in soil in the absence of ash tissues. We propose an amended life-cycle in which wind-dispersed, insectvectored or water-spread conidia infect ash and may sporulate in planta, as well as in forest debris. This amplifies inoculum levels of different strains in ash stands. In combination with their function as spermatia, conidia thus act to maximise gene flow between sympatric strains, including those originally present at low inoculum. Such mixing increases evolutionary potential, as well as enhancing the likelihood of gene introgression from closely-related strains or assimilation of further genetic diversity from parental Asian populations. This scenario increases the adaptability of H. fraxineus to new climates and, indeed, onto new host species.This work was fund by a grant from the BBSRC to the Nornex Consortium, BBS/E/J/000CA523, in association with DEFRA
A role for the asexual spores in infection of Fraxinus excelsior by the ash-dieback fungus Hymenoscyphus fraxineus
This is the final version of the article. Available from Springer Nature via the DOI in this record.There is another ORE record for this article: http://hdl.handle.net/10871/33324The invasive pathogen, ash dieback fungus Hymenoscyphus fraxineus, is spreading rapidly across Europe. It shows high levels of outcrossing and limited population structure, even at the epidemic front. The anamorphic (asexual) form produces prolific conidia, thought to function solely as spermatia (male gametes), facilitating gene flow between sympatric strains. Here, we show that conidia are capable of germination on ash leaves and in vitro, and can infect seedlings via leaves or soil. In leaves, germlings form structures resembling fruiting bodies. Additionally, H. fraxineus colonises ash debris and grows in soil in the absence of ash tissues. We propose an amended life-cycle in which wind-dispersed, insectvectored or water-spread conidia infect ash and may sporulate in planta, as well as in forest debris. This amplifies inoculum levels of different strains in ash stands. In combination with their function as spermatia, conidia thus act to maximise gene flow between sympatric strains, including those originally present at low inoculum. Such mixing increases evolutionary potential, as well as enhancing the likelihood of gene introgression from closely-related strains or assimilation of further genetic diversity from parental Asian populations. This scenario increases the adaptability of H. fraxineus to new climates and, indeed, onto new host species.This work was funded by a grant from the BBSRC to the Nornex Consortium, BBS/E/J/000CA523, in association with DEFRA. We thank Dr Chris Thornton for useful discussions concerning fungal pathogens of soil and Dr Sreedhar Kilaru for kindly providing primers
AGE Survey: a tool to support the study and intervention on health and age at work
The complex relationship between age and work goes beyond the association
between the exposure to risk factors and early ageing. Only few studies attempt to
encompass this complexity and try to put this discussion in a temporal dimension,
considering the developments of health and work over lifetime.
This proposal presents some results of a study conducted in Portugal about working
conditions, occupational risks and health problems.
European studies, as ESTEV and VISAT, both in France, used a longitudinal design
with repeated measures in order to monitor health issues taking into account job
modifications and age evolution. From these experiences, other studies were
performed in this field, with less extensive instruments, for example the SVP50 and
EVREST. In Portugal we developed the first survey on health and age – AGE– based
on the previous experiences and supported by the strong network between
researchers from these groups.
The first AGE data collection was conducted in 2016, in collaboration with the
National Authority for Working Conditions. The survey was administrated by labour
inspectors in their regular visits to companies, with 3106 surveyed workers. AGE
dimensions focus on: working conditions (working time, schedules,
demands/resources, perceived risks); health complaints and the perceived (by
workers) relationship between these problems and their work, in order to analyse
the relationship between age, health and work; and questions about retirement
expectations, in order to identify retirement predictors.
The results show interesting relations between working conditions and the health
problems identified by workers and, with strong evidences that age plays a key role
in the capacity to recognise the connexion between work constraints and health
problems. Results also show different tendencies related to both perceived
expositions and perceived health problems for different age groups, emphasising
the need to consider the specificity of diverse situations in the moment of
intervention.
Findings also show that these health problems are frequently reported by workers,
as related to their work, mostly in work situations of co-exposition (when workers
are exposed to several constrains at the same time). The association of different
constraints seem to be particularly hard for workers, due to the high proportion of
reported health problems.info:eu-repo/semantics/acceptedVersio
A Brief Review on Dark Matter Annihilation Explanation for Excesses in Cosmic Ray
Recently data from PAMELA, ATIC, FERMI-LAT and HESS show that there are
excesses in the cosmic ray energy spectrum. PAMELA observed excesses
only in , but not in anti-proton spectrum. ATIC, FERMI-LAT and HESS
observed excesses in spectrum, but the detailed shapes are different
which requires future experimental observations to pin down the correct data
set. Nevertheless a lot of efforts have been made to explain the observed
excesses, and also why PAMELA only observed excesses in but not
in anti-proton. In this brief review we discuss one of the most popular
mechanisms to explain the data, the dark matter annihilation. It has long been
known that about 23% of our universe is made of relic dark matter. If the relic
dark matter was thermally produced, the annihilation rate is constrained
resulting in the need of a large boost factor to explain the data. We will
discuss in detail how a large boost factor can be obtained by the Sommerfeld
and Briet-Wigner enhancement mechanisms. Some implications for particle physics
model buildings will also be discussed.Comment: 22 pages, 6 figures. Several typoes corrected and some references
added. Published in Mod. Phys. Lett. A, Vol. 24, No. 27 (2009) pp. 2139-216
A Definitive Signal of Multiple Supersymmetry Breaking
If the lightest observable-sector supersymmetric particle (LOSP) is charged
and long-lived, then it may be possible to indirectly measure the Planck mass
at the LHC and provide a spectacular confirmation of supergravity as a symmetry
of nature. Unfortunately, this proposal is only feasible if the gravitino is
heavy enough to be measured at colliders, and this condition is in direct
conflict with constraints from big bang nucleosynthesis (BBN). In this work, we
show that the BBN bound can be naturally evaded in the presence of multiple
sectors which independently break supersymmetry, since there is a new decay
channel of the LOSP to a goldstino. Certain regions of parameter space allow
for a direct measurement of LOSP decays into both the goldstino and the
gravitino at the LHC. If the goldstino/gravitino mass ratio is measured to be
2, as suggested by theory, then this would provide dramatic verification of the
existence of multiple supersymmetry breaking and sequestering. A variety of
consistent cosmological scenarios are obtained within this framework. In
particular, if an R symmetry is imposed, then the gauge-gaugino-goldstino
interaction vertices can be forbidden. In this case, there is no bound on the
reheating temperature from goldstino overproduction, and thermal leptogenesis
can be accommodated consistently with gravitino dark matter.Comment: 10 pages, 5 figures, title changed to match the version published in
JHE
Decaying Hidden Dark Matter in Warped Compactification
The recent PAMELA and ATIC/Fermi/HESS experiments have observed an excess of
electrons and positrons, but not anti-protons, in the high energy cosmic rays.
To explain this result, we construct a decaying hidden dark matter model in
string theory compactification that incorporates the following two ingredients,
the hidden dark matter scenario in warped compactification and the
phenomenological proposal of hidden light particles that decay to the Standard
Model. In this model, on higher dimensional warped branes, various warped
Kaluza-Klein particles and the zero-mode of gauge field play roles of the
hidden dark matter or mediators to the Standard Model.Comment: 15 pages; v4, several clarifications added, update on Fermi/HESS
result
Parenting interventions for male young offenders: a review of the evidence on what works
Approximately one in four incarcerated male young offenders in the UK is an actual or expectant father. This paper reviews evidence on the effectiveness of parenting interventions for male young offenders. We conducted systematic searches across 20 databases and consulted experts. Twelve relevant evaluations were identified: 10 from the UK, of programmes for incarcerated young offenders, and two from the US, of programmes for young parolees. None used experimental methods or included a comparison group. They suggest that participants like the courses, find them useful, and the interventions may improve knowledge about, and attitudes to, parenting. Future interventions should incorporate elements of promising parenting interventions with young fathers in the community, for example, and/or with older incarcerated parents. Young offender fathers have specific developmental, rehabilitative, and contextual needs. Future evaluations should collect longer-term behavioural parent and child outcome data and should use comparison groups and, ideally, randomization
Abelian Hidden Sectors at a GeV
We discuss mechanisms for naturally generating GeV-scale hidden sectors in
the context of weak-scale supersymmetry. Such low mass scales can arise when
hidden sectors are more weakly coupled to supersymmetry breaking than the
visible sector, as happens when supersymmetry breaking is communicated to the
visible sector by gauge interactions under which the hidden sector is
uncharged, or if the hidden sector is sequestered from gravity-mediated
supersymmetry breaking. We study these mechanisms in detail in the context of
gauge and gaugino mediation, and present specific models of Abelian GeV-scale
hidden sectors. In particular, we discuss kinetic mixing of a U(1)_x gauge
force with hypercharge, singlets or bi-fundamentals which couple to both
sectors, and additional loop effects. Finally, we investigate the possible
relevance of such sectors for dark matter phenomenology, as well as for low-
and high-energy collider searches.Comment: 43 pages, no figures; v2: to match JHEP versio
Singlet Portal to the Hidden Sector
Ultraviolet physics typically induces a kinetic mixing between gauge singlets
which is marginal and hence non-decoupling in the infrared. In singlet
extensions of the minimal supersymmetric standard model, e.g. the
next-to-minimal supersymmetric standard model, this furnishes a well motivated
and distinctive portal connecting the visible sector to any hidden sector which
contains a singlet chiral superfield. In the presence of singlet kinetic
mixing, the hidden sector automatically acquires a light mass scale in the
range 0.1 - 100 GeV induced by electroweak symmetry breaking. In theories with
R-parity conservation, superparticles produced at the LHC invariably cascade
decay into hidden sector particles. Since the hidden sector singlet couples to
the visible sector via the Higgs sector, these cascades necessarily produce a
Higgs boson in an order 0.01 - 1 fraction of events. Furthermore,
supersymmetric cascades typically produce highly boosted, low-mass hidden
sector singlets decaying visibly, albeit with displacement, into the heaviest
standard model particles which are kinematically accessible. We study
experimental constraints on this broad class of theories, as well as the role
of singlet kinetic mixing in direct detection of hidden sector dark matter. We
also present related theories in which a hidden sector singlet interacts with
the visible sector through kinetic mixing with right-handed neutrinos.Comment: 12 pages, 5 figure
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