168 research outputs found
The effects of different warm stratification periods on the seed germination of some Rosa taxa
In this study, the effects of different warm stratification periods on the seed germination of some Rosa species such as Rosa heckellana ssp. vanheurckiana, Rosa canina, Rosa pulverelanta and Rosa dumalis naturally grown in the Van region were investigated. In 2007, seeds of these species were kept at 25°C warm stratification for 10, 11 and 12 weeks, and then transferred to 5°C for cold stratification till the initiation of germination. Germination response to treatments of R. heckellana ssp. vanheurckiana seeds was different compared to the other species. The seeds of R. heckellana ssp. vanheurckiana germinated in a short time (when they kept in warm stratification followed by cold stratification between 1 - 3 weeks). The seeds of the other species required 5 months of cold stratification after warm stratification to overcome seed dormancy. The overall germination percentage were 18.80% in R. canina, 13.80% in R. pulverelanta and 13.53% in R. dumalis at 25°C of warm stratification followed by 5°C cold stratification. We determined that for these three taxa, the most appropriate method of stratification was 11 week warm stratification followed by cold stratification
Mapping interactions with the chaperone network reveals factors that protect against tau aggregation.
A network of molecular chaperones is known to bind proteins ('clients') and balance their folding, function and turnover. However, it is often unclear which chaperones are critical for selective recognition of individual clients. It is also not clear why these key chaperones might fail in protein-aggregation diseases. Here, we utilized human microtubule-associated protein tau (MAPT or tau) as a model client to survey interactions between ~30 purified chaperones and ~20 disease-associated tau variants (~600 combinations). From this large-scale analysis, we identified human DnaJA2 as an unexpected, but potent, inhibitor of tau aggregation. DnaJA2 levels were correlated with tau pathology in human brains, supporting the idea that it is an important regulator of tau homeostasis. Of note, we found that some disease-associated tau variants were relatively immune to interactions with chaperones, suggesting a model in which avoiding physical recognition by chaperone networks may contribute to disease
Combining functional weed ecology and crop stable isotope ratios to identify cultivation intensity: a comparison of cereal production regimes in Haute Provence, France and Asturias, Spain
This investigation combines two independent
methods of identifying crop growing conditions and husbandry
practices—functional weed ecology and crop stable
carbon and nitrogen isotope analysis—in order to assess
their potential for inferring the intensity of past cereal
production systems using archaeobotanical assemblages.
Present-day organic cereal farming in Haute Provence,
France features crop varieties adapted to low-nutrient soils
managed through crop rotation, with little to no manuring.
Weed quadrat survey of 60 crop field transects in this region
revealed that floristic variation primarily reflects
geographical differences. Functional ecological weed data
clearly distinguish the Provence fields from those surveyed
in a previous study of intensively managed spelt wheat in
Asturias, north-western Spain: as expected, weed ecological
data reflect higher soil fertility and disturbance in
Asturias. Similarly, crop stable nitrogen isotope values
distinguish between intensive manuring in Asturias and
long-term cultivation with minimal manuring in Haute
Provence. The new model of cereal cultivation intensity
based on weed ecology and crop isotope values in Haute
Provence and Asturias was tested through application to
two other present-day regimes, successfully identifying a
high-intensity regime in the Sighisoara region, Romania,
and low-intensity production in Kastamonu, Turkey. Application
of this new model to Neolithic archaeobotanical
assemblages in central Europe suggests that early farming
tended to be intensive, and likely incorporated manuring,
but also exhibited considerable variation, providing a finer
grained understanding of cultivation intensity than previously
available
Collider aspects of flavour physics at high Q
This review presents flavour related issues in the production and decays of
heavy states at LHC, both from the experimental side and from the theoretical
side. We review top quark physics and discuss flavour aspects of several
extensions of the Standard Model, such as supersymmetry, little Higgs model or
models with extra dimensions. This includes discovery aspects as well as
measurement of several properties of these heavy states. We also present public
available computational tools related to this topic.Comment: Report of Working Group 1 of the CERN Workshop ``Flavour in the era
of the LHC'', Geneva, Switzerland, November 2005 -- March 200
Periodicities in the Daily Proton Fluxes from 2011 to 2019 Measured by the Alpha Magnetic Spectrometer on the International Space Station from 1 to 100 GV
We present the precision measurement of the daily proton fluxes in cosmic rays from May 20, 2011 to October 29, 2019 (a total of 2824 days or 114 Bartels rotations) in the rigidity interval from 1 to 100 GV based on 5.5×109 protons collected with the Alpha Magnetic Spectrometer aboard the International Space Station. The proton fluxes exhibit variations on multiple timescales. From 2014 to 2018, we observed recurrent flux variations with a period of 27 days. Shorter periods of 9 days and 13.5 days are observed in 2016. The strength of all three periodicities changes with time and rigidity. The rigidity dependence of the 27-day periodicity is different from the rigidity dependences of 9-day and 13.5-day periods. Unexpectedly, the strength of 9-day and 13.5-day periodicities increases with increasing rigidities up to ∼10 GV and ∼20 GV, respectively. Then the strength of the periodicities decreases with increasing rigidity up to 100 GV.</p
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