3,012 research outputs found
Inverse Compton X-rays from the radio galaxy 3C 219
We report the results from a Chandra observation of the powerful nearby
(z=0.1744) radio galaxy 3C 219. We find evidence for non-thermal X-ray emission
from the radio lobes which fits fairly well with a combination of inverse
Compton scattering of Cosmic Microwave Background radiation and of nuclear
photons with the relativistic electrons in the lobes. The comparison between
radio synchrotron and IC emission yields a magnetic field strength
significantly lower (about a factor 3) than that calculated under minimum
energy conditions; the source energetics is then dominated by the relativistic
particles.Comment: 5 pages, 2 color figures, Accepted for publication in MNRAS pink
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Abstract Concepts and Aging: An Embodied and Grounded Perspective
How do we represent abstract concepts, as “justice” and “phantasy”? This issue has become hotly debated within embodied and grounded cognition views (for reviews: Pecher et al., 2011; Dove, 2016; Borghi et al., 2017). It is in fact unclear how such views can explain how we represent concepts that do not have single concrete referents and are rather detached from sensory experience (Barsalou, 2003; Binder, 2016). In spite of the increasing interest for this issue, to date evidence on abstract concepts across the lifespan is limited. Assuming that the representation of abstract concepts changes from adulthood to older age, in this paper we discuss how a new embodied and grounded proposal, the Words As social Tools (WAT) view (Borghi and Binkofski, 2014), can explain how abstract concepts are represented by older individuals. More specifically we will advance hypotheses on abstract concepts in aging focusing on WAT, and reinterpret previous findings in light of it. We propose that WAT can account for existing findings and provide a suitable framework to test conceptual knowledge in older adult
Some non-linear function theoretic properties of Riemannian manifolds
We study the appropriate versions of parabolicity stochastic completeness and related Liouville properties for a general class of operators which include the -Laplace operator, and the non linear singular operators in non-diagonal form considered by J. Serrin and collaborators
A finiteness theorem for the space of Lp harmonic sections
In this paper we give a unified and improved treatment to finite dimensionality results for subspaces of Lp harmonic sections of Riemannian or Hermitian vector bundles over complete manifolds. The geometric conditions on the manifold are subsumed by the assumption that the Morse index of a related Schro \u308dinger operator is finite. Applications of the finiteness theorem to concrete geometric situations are also presented
Applications of response surface methodology approach to determine the effect of temperature, time of incubation and light conditions on germination and germ tube growth of Puccinia coronata f.sp. avenae urediosopores
Crown rust caused by Puccinia coronata f.sp. avenae is the most damaging disease on oat. This work analyzed the effects of temperature and illumination regime during different time of incubation on both spore germination and germ tube growth, using both analysis of variance (ANOVA) and response surface methodology (RSM). This study reveals that the maximum of germination approached 95% under dark conditions at 20°C. Similarly, the maximum germ tube length was 125±23 μm under dark conditions at the same temperature after 18 h. Both spore germination and germ tube growth were observed over a wider temperature range of 5 to 30°C. The darkness conditions seem to enhance significantly (P < 0.05) both the germination and germ tube growth. After 4 h of incubation, germination was significantly higher under darkness regime at 15, 20 and 25°C than under light conditions. The effect of darkness conditions on germ tube growth paralleled its effect on germination. Furthermore, the response surface methodology (RSM) was applied to determine the optimal conditions of temperature, time and illuminations conditions for both the germination process and germ tube growth of urediospores for P. coronata f.sp. coronata. Values for the optimal germination and germ tube growth were 20°C and 8 h under darkness conditions. Moreover, urediospores of P. coronata f.sp. coronata germination and germ tube growth had followed a quadratic response function on temperature (R² = 0.94 and 0.97). On the other hand, the experimental values were in good agreement with the predicted ones and the model was highly significant with the correlation coefficient R being 0.97 and 0.98, respectively for germination and germ tube growth.Key words: Puccinia coronata f.sp. avenae, temperature, time, illuminations conditions, germination process, germ tube growth, urediospores
Chandra detection of the radio and optical double hot spot of 3C 351
In this letter we report a Chandra X-ray detection of the double northern hot
spot of the radio quasar 3C 351. The hot spot has also been observed in the
optical with the Hubble Space Telescope (R-band) and with the 3.5m. Telescopio
Nazionale Galileo (B-band). The radio-to-optical and X-ray spectra are
interpreted as the results of the synchrotron and synchrotron-self-Compton
(SSC) mechanisms, respectively, with hot-spot magnetic field strengths ~3 times
smaller than the equipartition values. In the framework of shock acceleration
theory, we show that the requirement for such a relatively small field strength
is in agreement with the fitted synchrotron spectral models and with the sizes
of the hot spots. Finally, we show that the combination of a lower magnetic
field strength with the high frequencies of the synchrotron cut-off in the
fitted synchrotron spectra provides strong evidence for electron acceleration
in the hot spots.Comment: 16 pag. + 2 .PS figures (fig.2 color), ApJ Letter in pres
Resonate and fire dynamics in Complex Oscillation Based Test of analog filters
Recently, proposals have been made for enhancing the Oscillation Based Test (OBT) methodology by using non-plain oscillation regimes, leading to so called Complex Oscillation Based Test (COBT). Here we focus on a recently illustrated strategy for the testing of analog 2nd order filters, showing that the COBT dynamics is quite similar to that expressed by Resonate & Fire (R+F) neuron models. In this interpretation, the testing approach can be related to firing-rate measures. A brief description is given of the mathematical models necessary to achieve a precise characterization of firing times, showing how it can be used for testing purposes. A practical example with simulation data is also provided. © 2011 IEEE
SHEDDING LIGHT ON GLIOBLASTOMA AND DERIVED EXTRACELLULAR VESICLES IN ONE CLIC
ABSTRACT
The treatment of glioblastoma (GBM) still represents a tremendous clinical challenge, with the average survival that is not exceeding 14 months. Given the lack of reliable prognostic markers and druggable targets in GBM, several years ago our lab\u2019s interest focused on Chloride intracellular channel-1 (CLIC1), a protein belonging to a class of chloride channels that does not fit the classical paradigm of ion channels proteins. CLIC1 proteins can exist as both soluble globular protein and integral membrane protein with ion channel function. Upon oxidative stress, CLIC1 translocates from the cytoplasm to the plasma membrane where it exerts its function as a chloride (Cl-) channel. CLIC1 is overexpressed in several human solid tumors, including gliomas. In this study we demonstrated that CLIC1 silencing in cancer stem cells (CSCs) isolated from human GBM patients negatively influences both proliferative capacity and self-renewal properties in vitro and impairs the in vivo tumorigenic potential. Moreover, CLIC1 expression inversely associates with GBM patient survival, thus suggesting a potential exploitation of CLIC1 as a new molecular therapeutic target and a possible outcome predictor. CLIC1 has been identified as a secreted protein and detected in exosomes released from different cell types, including primary tumors. Extracellular vesicles (40-1000 nm) (EVs) are secreted by virtually all cell types that arise from the invagination and the budding of the limiting membrane of late endosomes (hence called multivesicular bodies, MVB). We showed that CLIC1 is a protein localized within EVs isolated by GBM cell lines and GBM-derived CSCs and by tuning CLIC1 expression within EVs it is possible to modulate cellular response to EVs both in vitro and in vivo.
Taken together, our data suggest that CLIC1 plays an important role in regulating GBM proliferation and tumorigenic status, experimental evidences hint the possible transmission of these features to recipient cells by EV secretion
The resolved fraction of the Cosmic X-ray Background
We present the X-ray source number counts in two energy bands (0.5-2 and 2-10
keV) from a very large source sample: we combine data of six different surveys,
both shallow wide field and deep pencil beam, performed with three different
satellites (ROSAT, Chandra and XMM-Newton). The sample covers with good
statistics the largest possible flux range so far: [2.4*10^-17 - 10^-11] cgs in
the soft band and [2.1*10^-16 - 8*10^{-12}]cgs in the hard band. Integrating
the flux distributions over this range and taking into account the (small)
contribution of the brightest sources we derive the flux density generated by
discrete sources in both bands. After a critical review of the literature
values of the total Cosmic X--Ray Background (CXB) we conclude that, with the
present data, the 94.3%, and 88.8% of the soft and hard CXB can be ascribed to
discrete source emission. If we extrapolate the analytical form of the Log
N--Log S distribution beyond the flux limit of our catalog in the soft band we
find that the flux from discrete sources at ~3*10^-18 cgs is consistent with
the entire CXB, whereas in the hard band it accounts for only 93% of the total
CXB at most, hinting for a faint and obscured population to arise at even
fainter fluxes.Comment: Accepted for publication in Ap
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