643 research outputs found
The double RGB in M 2: C, N, Sr and Ba abundances
The globular cluster M 2 has a photometrically detected double red giant
branch (RGB) sequence. We investigate here the chemical differences between the
two RGBs in order to gain insight in the star formation history of this
cluster. The low-resolution spectra, covering the blue spectral range, were
collected with the MODS spectrograph on the LBT, and analyzed via spectrum
synthesis technique. The high quality of the spectra allows us to measure C, N,
Ba, and Sr abundances relative to iron for 15 RGB stars distributed along the
two sequences. We add to the MODS sample C and N measurements for 35 additional
stars belonging to the blue RGB sequence, presented in Lardo et al. (2012). We
find a clear separation between the two groups of stars in s-process elements
as well as C and N content. Both groups display a C-N anti-correlation and the
red RGB stars are on average richer in C and N with respect to the blue RGB.
Our results reinforce the suggestion that M2 belongs to the family of globular
clusters with complex star formation history, together with Omega Cen, NGC
1851, and M 22.Comment: 11 pages, 8 figures. Accepted for publication in MNRA
Challenges and opportunities for more efficient water use and circular wastewater management. The case of Campania Region, Italy
By 2050, global demand for water is expected to increase by some 55% due to population growth and urbanization. The utilization of large amounts of freshwater in the world, generate huge volumes of wastewater of which, globally, more than 80% is discharged without treatment, thus causing impacts on aquatic ecosystems, human health and economic productivity. More sustainable practices of wastewater management are expected as a way towards circular bioeconomy (CBE) processes, whose goal is to implement closed systems promoting the systematic use of recycling, reuse and recovery of bioproducts and by-products and the reduction of waste generation. This approach, if adopted in the water and wastewater sector, can ensure environmental, economic and social benefits. The reuse of wastewater, on the one hand, reduces the volume of wastewater and the pressure on water bodies; on the other hand, the recovery of nutrients (P or N) and/or other high value bioproducts (biogas, cellulose, biopolymers) from wastewater offers numerous advantages in terms of supplying new raw bio-based materials that can be refed back to supply chains (thus substituting fossil resources) and, at the same time, producing cleaner water to be reused. Nevertheless, while in Europe many industries have demonstrated the ability to recycle and reuse water, in many regions of Italy the sustainable management of water and wastewater is not yet consolidated. In this study we explore the available technological, economic and environmental options concerning water use and wastewater treatment and we apply them to design appropriate scenarios for improved use efficiency and circular management. A comprehensive literature review of the most promising wastewater treatment processes for resources and energy valorization was conducted. The recovery of PHAs, struvite, nitrogen and algal biomass, as potential substitutes for conventional PET, phosphate and nitrogen chemical fertilizers and electricity, respectively, in addition to reusable treated water, were hypothesized and carefully discussed. Resulting scenarios are tested against the present situation of Campania Region (situated in Southern Italy) based on population and demand statistics, in order to develop strategies and policies potentially applicable locally and elsewhere
Cerebellum and neurodegenerative diseases: Beyond conventional magnetic resonance imaging
The cerebellum plays a key role in movement control and in cognition and cerebellar involvement is described in several neurodegenerative diseases. While conventional magnetic resonance imaging (MRI) is widely used for brain and cerebellar morphologic evaluation, advanced MRI techniques allow the investigation of cerebellar microstructural and functional characteristics. Volumetry, voxel-based morphometry, diffusion MRI based fiber tractography, resting state and task related functional MRI, perfusion, and proton MR spectroscopy are among the most common techniques applied to the study of cerebellum. In the present review, after providing a brief description of each technique's advantages and limitations, we focus on their application to the study of cerebellar injury in major neurodegenerative diseases, such as multiple sclerosis, Parkinson's and Alzheimer's disease and hereditary ataxia. A brief introduction to the pathological substrate of cerebellar involvement is provided for each disease, followed by the review of MRI studies exploring structural and functional cerebellar abnormalities and by a discussion of the clinical relevance of MRI measures of cerebellar damage in terms of both clinical status and cognitive performance
Somatic instability of the expanded GAA triplet-repeat sequence in Friedreich ataxia progresses throughout life
Friedreich ataxia (FRDA) patients are homozygous for expanded GAA triplet-repeat
alleles in the FXN gene. Primary neurodegeneration involving the dorsal root ganglia
(DRG) results in progressive ataxia. While it is known that DRG are inherently sensitive
to frataxin deficiency, recent observations also indicate that they show age-dependent,
further expansion of the GAA triplet-repeat mutation. Whether somatic instability is
progressive has not been systematically investigated in FRDA patients. Small pool PCR
analysis of ~2300 individual molecules from tissues of an 18-week fetus, homozygous
for expanded alleles, revealed very low levels of instability compared with adult-derived
tissues (4.2% versus 30.6%, P<0.0001). Mutation load in blood samples from multiple
patients and carriers increased significantly with age, ranging from 7.5% at 18-weeks
gestation to 78.7% at 49y (R=0.91; P=0.0001). Therefore, somatic instability in FRDA
occurs mostly after early embryonic development and progresses throughout life,
lending further support to the role of postnatal somatic instability in disease
pathogenesis
The Gaia spectrophotometric standard stars survey -II. Instrumental effects of six ground-based observing campaigns
The Gaia SpectroPhotometric Standard Stars (SPSS) survey started in 2006, it
was awarded almost 450 observing nights, and accumulated almost 100,000 raw
data frames, with both photometric and spectroscopic observations. Such large
observational effort requires careful, homogeneous, and automated data
reduction and quality control procedures. In this paper, we quantitatively
evaluate instrumental effects that might have a significant (i.e.,1%)
impact on the Gaia SPSS flux calibration. The measurements involve six
different instruments, monitored over the eight years of observations dedicated
to the Gaia flux standards campaigns: DOLORES@TNG in La Palma, EFOSC2@NTT and
ROSS@REM in La Silla, [email protected] in Calar Alto, BFOSC@Cassini in Loiano, and
[email protected] in San Pedro Martir. We examine and quantitatively evaluate the
following effects: CCD linearity and shutter times, calibration frames
stability, lamp flexures, second order contamination, light polarization, and
fringing. We present methods to correct for the relevant effects, which can be
applied to a wide range of observational projects at similar instruments.Comment: 16 pages, 13 figures, accepted for publication in Astron. Nach
SN 2002lt and GRB 021211: a SN/GRB Connection at z = 1
We present spectroscopic and photometric observations of the afterglow of GRB
021211 and the discovery of its associated supernova, SN 2002lt. The spectrum
shows a broad feature (FWHM = 150 A), around 3770 A (in the rest-frame of the
GRB), which we interpret as Ca H+K blueshifted by 14400 km/s. Potential sources
of contamination due to the host galaxy and/or residuals of telluric absorption
have been analyzed and ruled out. Overall, the spectrum shows a suggestive
resemblance with the one of the prototypical type-Ic SN 1994I. This might
indicate that GRBs are produced also by standard type-Ic supernovae.Comment: 6 pages, 5 color figures. Proceedings of the 2003 GRB Conference
(Santa Fe, NM, 2003 Sep 8-12). Needs aipprocs LaTeX clas
Laminar analysis of the cortical T1/T2-weighted ratio at 7T
Objective: In this observational study, we explored cortical structure as function of cortical depth through a laminar analysis of the T1/T2-weighted (T1w/T2w) ratio, which has been related to dendrite density in ex vivo brain tissue specimens of patients with MS.
Methods: In 39 patients (22 relapsing-remitting, 13 female, age 41.1 ± 10.6 years; 17 progressive, 11 female, age 54.1 ± 9.9 years) and 21 healthy controls (8 female, , age 41.6 ± 10.6 years), we performed a voxel-wise analysis of T1w/T2w ratio maps from high-resolution 7T images from the subpial surface to the gray matter/white matter boundary. Six layers were sampled to ensure accuracy based on mean cortical thickness and image resolution.
Results: At the voxel-wise comparison (p < 0.05, family wise error rate corrected), the whole MS group showed lower T1w/T2w ratio values than controls, both when considering the entire cortex and each individual layer, with peaks occurring in the fusiform, temporo-occipital, and superior and middle frontal cortex. In relapsing-remitting patients, differences in the T1w/T2w ratio were only identified in the subpial layer, with the peak occurring in the fusiform cortex, whereas results obtained in progressive patients mirrored the widespread damage found in the whole group.
Conclusions: Laminar analysis of T1w/T2w ratio mapping confirms the presence of cortical damage in MS and shows a variable expression of intracortical damage according to the disease phenotype. Although in the relapsing-remitting stage, only the subpial layer appears susceptible to damage, in progressive patients, widespread cortical abnormalities can be observed, not only, as described before, with regard to myelin/iron concentration but, possibly, to other microstructural features
The genomic landscape of 8-oxodG reveals enrichment at specific inherently fragile promoters
8-Oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) is the most common marker of oxidative stress and its accumulation within the genome has been associated with major human health issues such as cancer, aging, cardiovascular and neurodegenerative diseases. The characterization of the different genomic sites where 8-oxodG accumulates and the mechanisms underlying its formation are still poorly understood. Using OxiDIP-seq, we recently derived the genome-wide distribution of 8-oxodG in human non-tumorigenic epithelial breast cells (MCF10A). Here, we identify a subset of human promoters that accumulate 8-oxodG under steady-state condition. 8-oxodG nucleotides co-localize with double strand breaks (DSBs) at bidirectional and CG skewed promoters and their density correlate with RNA Polymerase II co-occupancy and transcription. Furthermore, by performing OxiDIP-seq in quiescent (G0) cells, we found a strong reduction of oxidatively-generated damage in the majority of 8-oxodG-positive promoters in the absence of DNA replication. Overall, our results suggest that the accumulation of 8-oxodG at gene promoters occurs through DNA replication-dependent or -independent mechanisms, with a possible contribution to the formation of cancer-associated translocation events
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