1,772 research outputs found
Mid-term report for the CORE Organic II funded project. âInnovative cropping Practices to increase soil health of organic fruit tree orchardsâ BIO-INCROP
Activities performed in the first part of BIO-INCROP project concern five of the eight main objectives fixed in the project proposal. They are:
Evaluation of soil borne pest and pathogens involved in replant disease
Role of rhizospheric bacterial and fungal communities in plant health
Selection of naturally available resources to increase microbial diversity and biomass
Compost and organic amendments
Evaluation of biologically active formulates
The document reports main research results and shows main items of dissemination activity performed in the first part of the project
The Spitzer View of Low-Metallicity Star Formation: II. Mrk 996, a Blue Compact Dwarf Galaxy with an Extremely Dense Nucleus
(abridged) We present new Spitzer, UKIRT and MMT observations of the blue
compact dwarf galaxy (BCD) Mrk 996, with an oxygen abundance of
12+log(O/H)=8.0. This galaxy has the peculiarity of possessing an
extraordinarily dense nuclear star-forming region, with a central density of
~10^6 cm^{-3}. The nuclear region of Mrk 996 is characterized by several
unusual properties: a very red color J-K = 1.8, broad and narrow emission-line
components, and ionizing radiation as hard as 54.9 eV, as implied by the
presence of the OIV 25.89 micron line. The nucleus is located within an
exponential disk with colors consistent with a single stellar population of age
>1 Gyr. The infrared morphology of Mrk 996 changes with wavelength. The IRS
spectrum shows strong narrow Polycyclic Aromatic Hydrocarbon (PAH) emission,
with narrow line widths and equivalent widths that are high for the metallicity
of Mrk 996. Gaseous nebular fine-structure lines are also seen. A CLOUDY model
requires that they originate in two distinct HII regions: a very dense HII
region of radius ~580 pc with densities declining from ~10^6 at the center to a
few hundreds cm^{-3} at the outer radius, where most of the optical lines
arise; and a HII region with a density of ~300 cm^{-3} that is hidden in the
optical but seen in the MIR. We suggest that the infrared lines arise mainly in
the optically obscured HII region while they are strongly suppressed by
collisional deexcitation in the optically visible one. The hard ionizing
radiation needed to account for the OIV 25.89 micron line is most likely due to
fast radiative shocks propagating in an interstellar medium. A hidden
population of Wolf-Rayet stars of type WNE-w or a hidden AGN as sources of hard
ionizing radiation are less likely possibilities.Comment: 48 pages, 13 figures, accepted for publication in the Astrophysical
Journa
Epidermal growth factor receptors in intracranial and breast tumours: their clinical significance.
A method to determine the binding of epidermal growth factor (EGF) to the particulate fraction of the cell has been established and evaluated using rat liver, human placenta, and tumours of human breast and brain. Little EGF receptor (EGFR) activity was detected in normal or benign tumour tissues except for meningioma (positive in 95% samples), but EGFR were present in 43% of 131 breast tumours and 75% of 55 primary cerebral tumours. Despite the strong inverse correlation between EGFR activity and oestrogen receptors in breast tumours and a tendency for high levels of EGFR activity to be associated with glioblastoma multiforme, analysis showed that EGFR was of little prognostic significance in patients with tumours of either breast or brain
Statistical Properties of Radio Emission from the Palomar Seyfert Galaxies
We have carried out an analysis of the radio and optical properties of a
statistical sample of 45 Seyfert galaxies from the Palomar spectroscopic survey
of nearby galaxies. We find that the space density of bright galaxies (-22 mag
<= M_{B_T} <= -18 mag) showing Seyfert activity is (1.25 +/- 0.38) X 10^{-3}
Mpc^{-3}, considerably higher than found in other Seyfert samples. Host galaxy
types, radio spectra, and radio source sizes are uncorrelated with Seyfert
type, as predicted by the unified schemes for active galaxies. Approximately
half of the detected galaxies have flat or inverted radio spectra, more than
expected based on previous samples. Surprisingly, Seyfert 1 galaxies are found
to have somewhat stronger radio sources than Seyfert 2 galaxies at 6 and 20 cm,
particularly among the galaxies with the weakest nuclear activity. We suggest
that this difference can be accommodated in the unified schemes if a minimum
level of Seyfert activity is required for a radio source to emerge from the
vicinity of the active nucleus. Below this level, Seyfert radio sources might
be suppressed by free-free absorption associated with the nuclear torus or a
compact narrow-line region, thus accounting for both the weakness of the radio
emission and the preponderance of flat spectra. Alternatively, the flat spectra
and weak radio sources might indicate that the weak active nuclei are fed by
advection-dominated accretion disks.Comment: 18 pages using emulateapj5, 13 embedded figures, accepted by Ap
Systematic review and meta-analysis of temozolomide in animal models of glioma:was clinical efficacy predicted?
Background:Malignant glioma is an aggressive tumour commonly associated with a dismal outcome despite optimal surgical and radio-chemotherapy. Since 2005 temozolomide has been established as first-line chemotherapy. We investigate the role of in vivo glioma models in predicting clinical efficacy.Methods:We searched three online databases to systematically identify publications testing temozolomide in animal models of glioma. Median survival and number of animals treated were extracted and quality was assessed using a 12-point scale; random effects meta-analysis was used to estimate efficacy. We analysed the impact of study design and quality and looked for evidence of publication bias.Results:We identified 60 publications using temozolomide in models of glioma, comprising 2443 animals. Temozolomide prolonged survival by a factor of 1.88 (95% CI 1.74-2.03) and reduced tumour volume by 50.4% (41.8-58.9) compared with untreated controls. Study design characteristics accounted for a significant proportion of between-study heterogeneity, and there was evidence of a significant publication bias.Conclusion:These data reflect those from clinical trials in that temozolomide improves survival and reduces tumour volume, even after accounting for publication bias. Experimental in vivo glioma studies of temozolomide differ from those of other glioma therapies in their consistent efficacy and successful translation into clinical medicine
On The Nature of Low Luminosity Narrow Line AGN
There is clear observational evidence that some narrow line (type 2) AGN have
a hidden broad line region (BLR), and are thus intrinsically broad line (type
1) AGN. Does this AGN unification applies for all type 2 AGN? Indirect
arguments suggest that some "true" type 2 AGN, i.e. AGN having no obscured BLR
do exist, but it is not clear why the BLR is missing in these AGN. Here we
point out a possible natural explanation. The observed radius-luminosity
relation for the BLR implies an increasing line width with decreasing
luminosity for a given black hole mass (Mbh). In addition, there appears to be
an upper limit to the observed width of broad emission lines in AGN of Delta
v_max~25,000 km/s, which may reflect a physical limit above which the BLR may
not be able to survive. Thus, at a low enough luminosity the BLR radius shrinks
below the Delta v_max radius, leaving no region where the BLR can exist,
although the AGN may remain otherwise `normal'. The implied minimum bolometric
luminosity required to sustain a BLR with Delta v<25,000 km/s is
L_min~10^{41.8}(Mbh}/10^8M_sun)^2. All AGN with L<L_min are expected to be
`true' type 2 AGN, i.e. narrow line AGN without a hidden BLR. Predictions for
the true nature of low luminosity AGN in two samples of nearby galaxies are
provided. These can be used to test the above L_min conjecture, and the
predictions of other models for the size and origin of the BLR
ISO-SWS spectroscopy of NGC 1068
We present ISO-SWS spectroscopy of NGC 1068 for the wavelength range 2.4 to
45um, detecting a total of 36 emission lines. Most of the observed transitions
are fine structure and recombination lines originating in the narrow line
region. We compare the line profiles of optical lines and reddening-insensitive
infrared lines to constrain the dynamical structure and extinction properties
of the NLR. The considerable differences found are most likely explained by two
effects. (1) The spatial structure of the NLR is a combination of a highly
ionized outflow cone and lower excitation extended emission. (2) Parts of the
NLR, mainly in the receding part at velocities above systemic, are subject to
extinction that is significantly suppressing optical emission. Line asymmetries
and net blueshifts remain, however, even for infrared fine structure lines
suffering very little obscuration. This may be either due to an intrinsic
asymmetry of the NLR, or due to a very high column density obscuring component
which is hiding part of the NLR even from infrared view. Mid-infrared emission
of molecular hydrogen in NGC 1068 arises in a dense molecular medium at
temperatures of a few hundred Kelvin that is most likely closely related to the
warm and dense components seen in the near-infrared H2 transitions, and in
millimeter wave tracers of molecular gas. Any emission of the putative pc-scale
molecular torus is likely overwhelmed by this larger scale emission.Comment: aastex (V4), 9 eps figures. Accepted by Ap
Is a minor-merger driving the nuclear activity in the Seyfert 2 galaxy NGC 2110?
We report on a detailed morphological and kinematic study of the isolated
non-barred nearby Seyfert 2 galaxy NGC 2110. We combine Integral Field optical
spectroscopy, with long-slit and WFPC2 imaging available in the HST archive to
investigate the fueling mechanism in this galaxy. Previous work (Wilson &
Baldwin 1985) concluded that the kinematic center of the galaxy is displaced
\~220 pc from the apparent mass center of the galaxy, and the ionized gas
follows a remarkably normal rotation curve. Our analysis based on the stellar
kinematics, 2D ionized gas velocity field and dispersion velocity, and high
spatial resolution morphology at V, I and Halpha reveals that: 1) The kinematic
center of NGC 2110 is at the nucleus of the galaxy. 2) The ionized gas is not
in pure rotational motion. 3) The morphology of the 2D distribution of the
emission line widths suggests the presence of a minor axis galactic outflow. 4)
The nucleus is blue-shifted with respect to the stellar systemic velocity,
suggesting the NLR gas is out-flowing due to the interaction with the radio
jet. 5) The ionized gas is red-shifted ~100 km/s over the corresponding
rotational motion south of the nucleus, and 240 km/s with respect to the
nuclear stellar systemic velocity. This velocity is coincident with the HI
red-shifted absorption velocity detected by Gallimore et al (1999). We discuss
the possibility that the kinematics of the south ionized gas could be perturbed
by the collision with a small satellite that impacted on NGC 2110 close to the
center with a highly inclined orbit. Additional support for this interpretation
are the radial dust lanes and tidal debris detected in the V un-sharp masked
image. We suggest that a minor-merger may have driven the nuclear activity in
NGC 2110.Comment: Full resolution images at
http://www.iaa.csic.es/~rosa/preprints/preprints.html or at
http://www.journals.uchicago.edu/ApJ/future.htm
Kinematic Linkage Between the Broad and Narrow Line Emitting Gas in AGN
We investigate the radial velocity difference between the [OIII]5007,4959 and
H-beta lines for a sample of 200 low redshift AGN. We identify seven objects
showing an [OIII]5007 blueshift relative to H-beta with amplitude larger than
250 km/s (blue "outliers"). These line shifts are found in sources where the
broad high ionization lines (e.g. CIV1549) also show a large systematic
blueshift. Such blueshifts occur only in the population A region of the
Eigenvector 1 parameter domain (that also contains NLSy1 sources). We suggest
that [OIII] blueshifts are also associated with the high ionization outflow
originating in these sources. This is a direct kinematic linkage between narrow
and broad line emitting gas.Comment: accepted for publication by ApJ Let
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