1,644 research outputs found
Nest predation in Afrotropical forest fragments shaped by inverse edge effects, timing of nest initiation and vegetation structure
High levels of nest predation influence the population dynamics of many tropical birds, especially when deforestation alters nest predator communities. The consequences of tropical forest fragmentation on nest predation, however, remain poorly understood, as natural predation patterns have only been well documented in a handful of tropical forests. Here, we show the results of an extensive study of predation on natural nests of Cabanis's Greenbul (Phyllastrephus cabanisi) during 3 years in a highly fragmented cloud forest in SE Kenya. Overall predation rates derived from 228 scrub nests averaged 69 %, matching the typical high predation level on tropical bird species. However, predation rates strongly varied in space and time, and a model that combined timing effects of fragment, edge, concealment, year and nest was best supported by our data. Nest predation rates consistently increased from forest edge to interior, opposing the classic edge effect on nest predation, and supporting the idea that classic edge effects are much rarer in Afrotropical forests than elsewhere. Nest concealment also affected predation rates, but the strength and direction of the relationship varied across breeding seasons and fragments. Apart from spatial variation, predation rates declined during the breeding season, although the strength of this pattern varied among breeding seasons. Complex and variable relationships with nest predation, such as those demonstrated here, suggest that several underlying mechanisms interact and imply that fixed nesting strategies may have variable-even opposing-fitness effects between years, sites and habitats
Entwicklung von Bekämpfungsstrategien für Meloidogyne halpa und Pratylenchus spp. im ökologischen Anbau von Möhren und Zwiebeln
Nematoden der Gattungen Meloidogyne und Pratylenchus zählen zu den Hauptschaderregern im ökologischen Anbau von Möhren und Zwiebeln. Typische Symptome sind geringes Wachstum, Deformationen der Ernteorgane, verstärkte Seitenwurzelbildung sowie Wurzelgallen (Meloidogyne) bzw. Wurzelläsionen (Pratylenchus). Beide Nematodengattungen haben ein sehr weites Wirtspflanzenspektrum und treten häufig gemeinsam auf. In dem vorliegenden Forschungsvorhaben werden Bekämpfungsstrategien für Meloidogyne und Pratylenchus unter praxisüblichen Bedingungen entwickelt
The 125th anniversary of the first postulation of the soil origin of endophytic bacteria – a tribute to M.L.V. Galippe
In both managed and natural ecosystems, a wide range of various non-nodulating bacteria can thrive as endophytes in the plant interior, and some can be beneficial to their hosts (Hallmann and Berg 2007; Reinhold-Hurek and Hurek 2011). Colonizationmechanisms, the ecology and functioning of these endophytic bacteria as well as their interactions with plants have been investigated (Hardoim et al. 2008; Compant et al. 2010). Although the source of colonization can also be the spermosphere, anthosphere, caulosphere, and the phyllosphere,most endophytic bacteria are derived from the soil environment (Hallmann and Berg 2007; Compant et al. 2010)
New attempts to understand nanodiamond stardust
We report on a concerted effort aimed at understanding the origin and history
of the pre-solar nanodiamonds in meteorites including the astrophysical sources
of the observed isotopic abundance signatures. This includes measurement of
light elements by secondary ion mass spectrometry (SIMS), analysis of
additional heavy trace elements by accelerator mass spectrometry (AMS) and
dynamic calculations of r-process nucleosynthesis with updated nuclear
properties. Results obtained indicate: a) there is no evidence for the former
presence of now extinct 26Al and 44Ti in our diamond samples other than what
can be attributed to silicon carbide and other "impurities"; this does not
offer support for a supernova (SN) origin but neither does it negate it; b)
analysis by AMS of platinum in "bulk diamond" yields an overabundance of r-only
198Pt that at face value seems more consistent with the neutron burst than with
the separation model for the origin of heavy trace elements in the diamonds,
although this conclusion is not firm given analytical uncertainties; c) if the
Xe-H pattern was established by an unadulterated r-process, it must have been a
strong variant of the main r-process, which possibly could also account for the
new observations in platinum.Comment: Workshop on Astronomy with Radioactvities VII; Publications of the
Astronomical Society of Australia, accepte
The ANTARES Collaboration: Contributions to ICRC 2017 Part II: The multi-messenger program
Papers on the ANTARES multi-messenger program, prepared for the 35th
International Cosmic Ray Conference (ICRC 2017, Busan, South Korea) by the
ANTARES Collaboratio
The ANTARES Collaboration: Contributions to ICRC 2017 Part I: Neutrino astronomy (diffuse fluxes and point sources)
Papers on neutrino astronomy (diffuse fluxes and point sources, prepared for
the 35th International Cosmic Ray Conference (ICRC 2017, Busan, South Korea) by
the ANTARES Collaboratio
The ANTARES Collaboration: Contributions to ICRC 2017 Part III: Searches for dark matter and exotics, neutrino oscillations and detector calibration
Papers on the searches for dark matter and exotics, neutrino oscillations and
detector calibration, prepared for the 35th International Cosmic Ray Conference
(ICRC 2017, Busan, South Korea) by the ANTARES Collaboratio
Ring closing reaction in diarylethene captured by femtosecond electron crystallography
The photoinduced ring-closing reaction in diarylethene, which serves as a model system for understanding reactive crossings through conical intersections, was directly observed with atomic resolution using femtosecond electron diffraction. Complementary ab initio calculations were also performed. Immediately following photoexcitation, subpicosecond structural changes associated with the formation of an open-ring excited-state intermediate were resolved. The key motion is the rotation of the thiophene rings, which significantly decreases the distance between the reactive carbon atoms prior to ring closing. Subsequently, on the few picosecond time scale, localized torsional motions of the carbon atoms lead to the formation of the closed-ring photoproduct. These direct observations of the molecular motions driving an organic chemical reaction were only made possible through the development of an ultrabright electron source to capture the atomic motions within the limited number of sampling frames and the low data acquisition rate dictated by the intrinsically poor thermal conductivity and limited photoreversibility of organic materials
Visualization of grapevine root colonization by the Saharan soil isolate Saccharothrix algeriensis NRRL B-24137 using DOPE-FISH microscopy
Background and aim There is currently a gap of
knowledge regarding whether some beneficial bacteria
isolated from desert soils can colonize epi- and
endophytically plants of temperate regions. In this
study, the early steps of the colonization process of
one of these bacteria, Saccharothrix algeriensis NRRL
B-24137, was studied on grapevine roots to determine
if this beneficial strain can colonize a non-natural host
plant. An improved method of fluorescence in situ
hybridization (FISH), the double labeling of oligonucleotide
probes (DOPE)-FISH technique was used to
visualize the colonization behavior of such bacteria as well as to determine if the method could be used to
track microbes on and inside plants.
Methods A probe specific to Saccharothrix spp. was
firstly designed. Visualization of the colonization behavior
of S. algeriensis NRRL B-24137 on and inside
roots of grapevine plants was then carried out with
DOPE-FISH microscopy.
Results The results showed that 10 days after inoculation,
the strain could colonize the root hair zone, root
elongation zone, as well as root emergence sites by
establishing different forms of bacterial structures as
revealed by the DOPE-FISH technique. Further observations
showed that the strain could be also endophytic
inside the endorhiza of grapevine plants.
Conclusions Taking into account the natural niches of
this beneficial strain, this study exemplifies that, in
spite of its isolation from desert soil, the strain can
establish populations as well as subpopulations on and
inside grapevine plants and that the DOPE-FISH tool
can allow to detect it
The Antares Collaboration : Contributions to the 34th International Cosmic Ray Conference (ICRC 2015, The Hague)
The ANTARES detector, completed in 2008, is the largest neutrino telescope in the Northern hemisphere. Located at a depth of 2.5 km in the Mediterranean Sea, 40 km off the Toulon shore, its main goal is the search for astrophysical high energy neutrinos. In this paper we collect the 21 contributions of the ANTARES collaboration to the 34th International Cosmic Ray Conference (ICRC 2015). The scientific output is very rich and the contributions included in these proceedings cover the main physics results, ranging from steady point sources, diffuse searches, multi-messenger analyses to exotic physics
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