4,500 research outputs found
Gravitational and electromagnetic emission by magnetized coalescing binary systems
We discuss the possibility to obtain an electromagnetic emission accompanying
the gravitational waves emitted in the coalescence of a compact binary system.
Motivated by the existence of black hole configurations with open magnetic
field lines along the rotation axis, we consider a magnetic dipole in the
system, the evolution of which leads to (i) electromagnetic radiation, and (ii)
a contribution to the gravitational radiation, the luminosity of both being
evaluated. Starting from the observations on magnetars, we impose upper limits
for both the electromagnetic emission and the contribution of the magnetic
dipole to the gravitational wave emission. Adopting this model for the
evolution of neutron star binaries leading to short gamma ray bursts, we
compare the correction originated by the electromagnetic field to the
gravitational waves emission, finding that they are comparable for particular
values of the magnetic field and of the orbital radius of the binary system.
Finally we calculate the electromagnetic and gravitational wave energy outputs
which result comparable for some values of magnetic field and radius.Comment: 9 pages, 3 figures, to appear in Astroph. Sp.Scienc
The Distribution of Mass in the Orion Dwarf Galaxy
Dwarf galaxies are good candidates to investigate the nature of Dark Matter,
because their kinematics are dominated by this component down to small
galactocentric radii. We present here the results of detailed kinematic
analysis and mass modelling of the Orion dwarf galaxy, for which we derive a
high quality and high resolution rotation curve that contains negligible
non-circular motions and we correct it for the asymmetric drift. Moreover, we
leverage the proximity (D = 5.4 kpc) and convenient inclination (47{\deg}) to
produce reliable mass models of this system. We find that the Universal
Rotation Curve mass model (Freeman disk + Burkert halo + gas disk) fits the
observational data accurately. In contrast, the NFW halo + Freeman disk + gas
disk mass model is unable to reproduce the observed Rotation Curve, a common
outcome in dwarf galaxies. Finally, we attempt to fit the data with a MOdified
Newtonian Dynamics (MOND) prescription. With the present data and with the
present assumptions on distance, stellar mass, constant inclination and
reliability of the gaseous mass, the MOND "amplification" of the baryonic
component appears to be too small to mimic the required "dark component". The
Orion dwarf reveals a cored DM density distribution and a possible tension
between observations and the canonical MOND formalism.Comment: 8 pages, 9 figures, accepted for publication in MNRA
An Unusual Cause of Dementia: Essential Diagnostic Elements of Corticobasal Degeneration—A Case Report and Review of the Literature
Corticobasal degeneration (CBD) is an uncommon, sporadic, neurodegenerative disorder of mid- to late-adult life. We describe a further example of the pathologic heterogeneity of this condition. A 71-year-old woman initially presented dysarthria, clumsiness, progressive asymmetric bradykinesia, and rigidity in left arm. Rigidity gradually involved ipsilateral leg; postural instability with falls, blepharospasm, and dysphagia subsequently developed.
She has been previously diagnosed as unresponsive Parkinson's Disease. At our clinical examination, she presented left upper-arm-fixed-dystonia, spasticity in left lower limb and pyramidal signs (Babinski and Hoffmann). Brain MRI showed asymmetric cortical atrophy in the right frontotemporal cortex. Neuropsychological examination showed an impairment in visuospatial functioning, frontal-executive dysfunction, and hemineglect.
This case demonstrates that association of asymmetrical focal cortical and subcortical features remains the clinical hallmark of this condition. There are no absolute markers for the clinical diagnosis that is complicated by the variability of presentation involving also cognitive symptoms that are reviewed in the paper. Despite the difficulty of diagnosing CBD, somatosensory evoked potentials, motor evoked potentials, long latency reflexes, and correlations between results on electroencephalography (EEG) and electromyography (EMG) provide further support for a CBD diagnosis. These techniques are also used to identify neurophysiological correlates of the neurological signs of the disease
Can anthocyanin presence ameliorate the photosynthetic performance of Prunus saplings subjected to polyethylene glycol-simulated water stress?
The aim was the evaluation of the biochemical and physiological responses of green- (GP) and red-leafed (RP) Prunus
cerasifera mature leaves to 20 d of polyethylene glycol (PEG 6000)-induced water stress in order to elucidate a possible
ameliorative role exerted by anthocyanins. At 10 d, the anthocyanin content remained unchanged in RP water-stressed
leaves. Photosynthetic rate was lower in GP than that of RP (83.4 vs. 76.5%, respectively), paralleled by a higher degree of
photoinhibition (Fv/Fm) in GP leaves. Leaves of GP accounted for higher content of soluble sugars at 10 d, when RP only
showed a slight sucrose increase. At 20 d of stress, both morphs recovered their Fv/Fm values, suggesting the ability of both
genotypes to adjust their photosynthetic metabolism under conditions of water stress. In conclusion, besides the sunscreen
role served by anthocyanins, the carbon sink by these flavonoids might have further prevented sugar accumulation and the
consequent sugar-promoted feedback regulation of photosynthesis in drought-stressed red leaves
Starving leukemia to induce differentiation
A new study shows that fasting induces the differentiation and elimination of some types of leukemia in mice, which implicates fasting or its mimetics as a novel strategy for the treatment of this disease
Combination of baseline LDH, performance status and age as integrated algorithm to identify solid tumor patients with higher probability of response to anti PD-1 and PD-l1 monoclonal antibodies
Predictive biomarkers of response to immune-checkpoint inhibitors (ICIs) are an urgent clinical need. The aim of this study is to identify manageable parameters to use in clinical practice to select patients with higher probability of response to ICIs. Two-hundred-and-seventy-one consecutive metastatic solid tumor patients, treated from 2013 until 2017 with anti-Programmed death-ligand 1 (PD-L1)/programmed cell death protein 1 (PD-1) ICIs, were evaluated for baseline lactate dehydrogenase (LDH) serum level, performance status (PS), age, neutrophil-lymphocyte ratio, type of immunotherapy, number of metastatic sites, histology, and sex. A training and validation set were used to build and test models, respectively. The variables\u2019 effects were assessed through odds ratio estimates (OR) and area under the receive operating characteristic curves (AUC), from univariate and multivariate logistic regression models. A final multivariate model with LDH, age and PS showed significant ORs and an AUC of 0.771. Results were statistically validated and used to devise an Excel algorithm to calculate the patient\u2019s response probabilities. We implemented an interactive Excel algorithm based on three variables (baseline LDH serum level, age and PS) which is able to provide a higher performance in response prediction to ICIs compared with LDH alone. This tool could be used in a real-life setting to identify ICIs in responding patients
The Apache Point Observatory Galactic Evolution Experiment (APOGEE) Spectrographs
We describe the design and performance of the near-infrared (1.51--1.70
micron), fiber-fed, multi-object (300 fibers), high resolution (R =
lambda/delta lambda ~ 22,500) spectrograph built for the Apache Point
Observatory Galactic Evolution Experiment (APOGEE). APOGEE is a survey of ~
10^5 red giant stars that systematically sampled all Milky Way populations
(bulge, disk, and halo) to study the Galaxy's chemical and kinematical history.
It was part of the Sloan Digital Sky Survey III (SDSS-III) from 2011 -- 2014
using the 2.5 m Sloan Foundation Telescope at Apache Point Observatory, New
Mexico. The APOGEE-2 survey is now using the spectrograph as part of SDSS-IV,
as well as a second spectrograph, a close copy of the first, operating at the
2.5 m du Pont Telescope at Las Campanas Observatory in Chile. Although several
fiber-fed, multi-object, high resolution spectrographs have been built for
visual wavelength spectroscopy, the APOGEE spectrograph is one of the first
such instruments built for observations in the near-infrared. The instrument's
successful development was enabled by several key innovations, including a
"gang connector" to allow simultaneous connections of 300 fibers; hermetically
sealed feedthroughs to allow fibers to pass through the cryostat wall
continuously; the first cryogenically deployed mosaic volume phase holographic
grating; and a large refractive camera that includes mono-crystalline silicon
and fused silica elements with diameters as large as ~ 400 mm. This paper
contains a comprehensive description of all aspects of the instrument including
the fiber system, optics and opto-mechanics, detector arrays, mechanics and
cryogenics, instrument control, calibration system, optical performance and
stability, lessons learned, and design changes for the second instrument.Comment: 81 pages, 67 figures, PASP, accepte
Creedy, Jean Iris
The final stage of leaf ontogenesis is represented by senescence, a highly regulated process driven by a sequential cellular breakdown involving, as the first step, chloroplast dismantling with consequent reduction of photosynthetic efficiency. Different processes, such as pigment accumulation, could protect the vulnerable photosynthetic apparatus of senescent leaves. Although several studies have produced transcriptomic data on foliar senescence, just few works have attempted to explain differences in red and green leaves throughout ontogenesis. In this work, a transcriptomic approach was used on green and red leaves of Prunus cerasifera to unveil molecular differences from leaf maturity to senescence. Our analysis revealed a higher gene regulation in red leaves compared to green ones, during leaf transition. Most of the observed DEGs were shared and involved in transcription factor activities, senescing processes and cell wall remodelling. Significant differences were detected in cellular functions: genes related to photosystem I and II were highly down-regulated in the green genotype, whereas transcripts involved in flavonoid biosynthesis, such as UDP glucose-flavonoid-3-O-glucosyltransferase (UFGT) were exclusively up-regulated in red leaves. In addition, cellular functions involved in stress response (glutathione-S-transferase, Pathogen-Related) and sugar metabolism, such as three threalose-6-phosphate synthases, were activated in senescent red leaves. In conclusion, data suggests that P. cerasifera red genotypes can regulate a set of genes and molecular mechanisms that cope with senescence, promoting more advantages during leaf ontogenesis than compared to the green ones
Photosynthetic traits and biochemical responses in strawberry (Fragaria × ananassa duch.) leaves supplemented with led lights
Selected light wavebands promote plant development and/or the biosynthesis of targeted metabolites. This work offers new insights on the effects of red (R), green (G), blue (B), and white (W – R:G:B; 1:1:1) LED light supplementation on physiochemical traits of strawberry leaves. Gas exchange and chlorophyll fluorescence parameters, photosynthetic pigments, and superoxide anion (•O2–) content were analysed in plants grown for 1 (T1) and 17 (T17) d with light supplementations. At T1, light supplementations resulted in the enhancement of the de-epoxidation state of xanthophylls and nonphotochemical quenching, but no changes were observed in maximal photosynthetic rate (PNmax), irrespective of light spectra. At T17, xanthophyll contents remained higher only in R-supplemented plants. Overall, W light resulted in higher photosynthesis, whilst R and B light depressed PNmax values and promoted•O2 – formation at T17. G light did not induce variations in photosynthetic traits nor induced oxidative stress at both T1 and T17
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