7,715 research outputs found
Identification of Distinct Bacillus thuringiensis 4A4 Nematicidal Factors Using the Model Nematodes Pristionchus pacificus and Caenorhabditis elegans
Bacillus thuringiensis has been extensively used for the biological control of insect pests. Nematicidal B. thuringiensis strains have also been identified; however, virulence factors of such strains are poorly investigated. Here, we describe virulence factors of the nematicidal B. thuringiensis 4A4 strain, using the model nematodes Pristionchus pacificus and Caenorhabditis elegans. We show that B. thuringiensis 4A4 kills both nematodes via intestinal damage. Whole genome sequencing of B. thuringiensis 4A4 identified Cry21Ha, Cry1Ba, Vip1/Vip2 and β-exotoxin as potential nematicidal factors. Only Cry21Ha showed toxicity to C. elegans, while neither Cry nor Vip toxins were active against P. pacificus, when expressed in E. coli. Purified crystals also failed to intoxicate P. pacificus, while autoclaved spore-crystal mixture of B. thuringiensis 4A4 retained toxicity, suggesting that primary β-exotoxin is responsible for P. pacificus killing. In support of this, we found that a β-exotoxin-deficient variant of B. thuringiensis 4A4, generated by plasmid curing lost virulence to the nematodes. Thus, using two model nematodes we revealed virulence factors of the nematicidal strain B. thuringiensis 4A4 and showed the multifactorial nature of its virulence
Pregnancy-associated breast cancer - Special features in diagnosis and treatment
For obvious psychological reasons it is difficult to associate pregnancy - a life-giving period of our existence with life-threatening malignancies. Symptoms pointing to malignancy are often ignored by both patients and physicians, and this, together with the greater difficulty of diagnostic imaging, probably results in the proven delay in the detection of breast cancers during pregnancy. The diagnosis and treatment of breast cancer are becoming more and more important, as the fulfillment of the desire to have children is increasingly postponed until a later age associated with a higher risk of carcinoma, and improved cure rates of solid tumors no longer exclude subsequent pregnancies. The following article summarizes the special features of the diagnosis and primary therapy of pregnancy-associated breast cancer with particular consideration of cytostatic therapy
Evolution of the Mass-Metallicity relations in passive and star-forming galaxies from SPH-cosmological simulations
We present results from SPH-cosmological simulations, including
self-consistent modelling of SN feedback and chemical evolution, of galaxies
belonging to two clusters and twelve groups. We reproduce the mass-metallicity
(ZM) relation of galaxies classified in two samples according to their
star-forming activity, as parametrized by their sSFR, across a redshift range
up to z=2.
Its slope shows irrelevant evolution in the passive sample, being steeper in
groups than in clusters. However, the sub-sample of high-mass passive galaxies
only is characterized by a steep increase of the slope with redshift, from
which it can be inferred that the bulk of the slope evolution of the ZM
relation is driven by the more massive passive objects. (...ABRIDGED...)
The ZM relation for the star-forming sample reveals an increasing scatter
with redshift, indicating that it is still being built at early epochs. The
star-forming galaxies make up a tight sequence in the SFR-M_* plane at high
redshift, whose scatter increases with time alongside with the consolidation of
the passive sequence. We also confirm the anti-correlation between sSFR and
stellar mass, pointing at a key role of the former in determining the galaxy
downsizing, as the most significant means of diagnostics of the star formation
efficiency. Likewise, an anti-correlation between sSFR and metallicity can be
established for the star-forming galaxies, while on the contrary more active
galaxies in terms of simple SFR are also metal-richer.
We discuss these results in terms of the mechanisms driving the evolution
within the high- and low-mass regimes at different epochs: mergers,
feedback-driven outflows and the intrinsic variation of the star formation
efficiency.Comment: Emended list of author
Monte Carlo simulations of random copolymers at a selective interface
We investigate numerically using the bond--fluctuation model the adsorption
of a random AB--copolymer at the interface between two solvents. From our
results we infer several scaling relations: the radius of gyration of the
copolymer in the direction perpendicular to the interface () scales
with , the interfacial selectivity strength, as
where is the usual Flory exponent and
is the copolymer's length; furthermore the monomer density at the interface
scales as for small . We also determine numerically the
monomer densities in the two solvents and discuss their dependence on the
distance from the interface.Comment: Latex text file appended with figures.tar.g
A study on the multicolour evolution of Red Sequence galaxy populations: insights from hydrodynamical simulations and semi-analytical models
By means of our own cosmological-hydrodynamical simulation and
semi-analytical model we studied galaxy population properties in clusters and
groups, spanning over 10 different bands from UV to NIR, and their evolution
since redshift z=2. We compare our results in terms of galaxy red/blue
fractions and luminous-to-faint ratio (LFR) on the Red Sequence (RS) with
recent observational data reaching beyond z=1.5. Different selection criteria
were tested in order to retrieve galaxies belonging to the RS: either by their
quiescence degree measured from their specific SFR ("Dead Sequence"), or by
their position in a colour-colour plane which is also a function of sSFR. In
both cases, the colour cut and the limiting magnitude threshold were let
evolving with redshift, in order to follow the natural shift of the
characteristic luminosity in the LF.
We find that the Butcher-Oemler effect is wavelength-dependent, with the
fraction of blue galaxies increasing steeper in optical colours than in NIR.
Besides, only when applying a lower limit in terms of fixed absolute magnitude,
a steep BO effect can be reproduced, while the blue fraction results less
evolving when selecting samples by stellar mass or an evolving magnitude limit.
We then find that also the RS-LFR behaviour, highly debated in the literature,
is strongly dependent on the galaxy selection function: in particular its very
mild evolution recovered when measured in terms of stellar mass, is in
agreement with values reported for some of the highest redshift confirmed
(proto)clusters. As to differences through environments, we find that normal
groups and (to a lesser extent) cluster outskirts present the highest values of
both star forming fraction and LFR at low z, while fossil groups and cluster
cores the lowest: this separation among groups begins after z~0.5, while
earlier all group star forming properties are undistinguishable.Comment: revised version, A&A accepted (11 pages, 6 figures
Weekly Paclitaxel plus Capecitabine versus Docetaxel Every 3 Weeks plus Capecitabine in Metastatic Breast Cancer
Background. We performed a randomized phase II study comparing efficacy and toxicity of weekly paclitaxel 80 mg/m2 (Weetax) with three weekly docetaxel 75 mg/m2 (Threetax), both in combination with oral capecitabine 1000 mg/m2 twice daily for 2 weeks followed by a 1-week break.
Patients. Thirty-seven women with confirmed metastatic breast cancer were randomized.
Results. Median TTF was 174 (Weetax) versus 147 days (Threetax) (=0.472). Median OS was 933 (Weetax) versus 464 days (Threetax) (=0.191). Reasons for TTF were PD 8/18 (Weetax), 9/19 (Threetax); and toxicity: 8/18 (Weetax), 8/19 (Threetax). ORR was 72% (Weetax) versus 26% (Threetax) (=0.01). The Threetax-combination resulted in a higher incidence of leuco-/neutropenia compared to Weetax. Grade II anemia was more pronounced in the Weetax group. No difference was found in quality of life.
Conclusion. Taxanes in combination with capecitabine resulted in a high level of toxicity. Taxanes and capecitabine should be considered given sequentially and not in combination
Organizing the distribution of income in the national football league
The article is devoted to the income of the National football League. The article considers the questions of the analysis of the economy of the NFL, the organization of the income distribution in the League, as well as advertising and sponsorship and commercial licensing
Organizing the distribution of income in the national football league
The article is devoted to the income of the National football League. The article considers the questions of the analysis of the economy of the NFL, the organization of the income distribution in the League, as well as advertising and sponsorship and commercial licensing
Localization transition of random copolymers at interfaces
We consider adsorption of random copolymer chains onto an interface within
the model of Garel et al. Europhysics Letters 8, 9 (1989). By using the replica
method the adsorption of the copolymer at the interface is mapped onto the
problem of finding the ground state of a quantum mechanical Hamiltonian. To
study this ground state we introduce a novel variational principle for the
Green's function, which generalizes the well-known Rayleigh-Ritz method of
Quantum Mechanics to nonstationary states. Minimization with an appropriate
trial Green's function enables us to find the phase diagram for the
localization-delocalization transition for an ideal random copolymer at the
interface.Comment: 5 page
Renormalization approach to many-particle systems
This paper presents a renormalization approach to many-particle systems. By
starting from a bare Hamiltonian with an
unperturbed part and a perturbation ,we define an
effective Hamiltonian which has a band-diagonal shape with respect to the
eigenbasis of . This means that all transition matrix elements are
suppressed which have energy differences larger than a given cutoff
that is smaller than the cutoff of the original Hamiltonian. This
property resembles a recent flow equation approach on the basis of continuous
unitary transformations. For demonstration of the method we discuss an exact
solvable model, as well as the Anderson-lattice model where the well-known
quasiparticle behavior of heavy fermions is derived.Comment: 11 pages, final version, to be published in Phys. Rev.
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