Abstract
Astro-rivelatore Gamma a Immagini Leggero (AGILE) is a space mission launched in 2007 to study X-ray and gamma-ray astronomy. The AGILE team developed real-time analysis pipelines to detect ...transient phenomena such as gamma-ray bursts (GRBs) and react to external science alerts received by other facilities. The AGILE anticoincidence system (ACS) comprises five panels surrounding the AGILE detectors to reject background-charged particles. It can also detect hard X-ray photons in the energy range 50–200 keV. The ACS data acquisition produces a time series for each panel. The time series are merged into a single multivariate time series (MTS). We present a new deep-learning model for the detection of GRBs in the ACS data using an anomaly detection technique. The model is implemented with a convolutional neural network autoencoder architecture trained in an unsupervised manner, using a data set of MTSs randomly extracted from the AGILE ACS data. The reconstruction error of the autoencoder is used as the anomaly score to classify the MTS. We calculated the associated
p
-value distribution, using more than 10
7
background-only MTSs, to define the statistical significance of the detections. We evaluate the trained model with a list of GRBs reported by the GRBWeb catalog. The results confirm the model’s capabilities to detect GRBs in the ACS data. We will implement this method in the AGILE real-time analysis pipeline.
Brain cells are immersed in a complex structure forming the extracellular matrix. The composition of the matrix gradually matures during postnatal development, as the brain circuitry reaches its ...adult form. The fully developed extracellular environment stabilizes neuronal connectivity and decreases cortical plasticity as highlighted by the demonstration that treatments degrading the matrix are able to restore synaptic plasticity in the adult brain. The mechanisms through which the matrix inhibits cortical plasticity are not fully clarified. Here we show that a prominent component of the matrix, chondroitin sulfate proteoglycans (CSPGs), restrains morphological changes of dendritic spines in the visual cortex of adult mice. By means of in vivo and in vitro two-photon imaging and electrophysiology, we find that after enzymatic digestion of CSPGs, cortical spines become more motile and express a larger degree of structural and functional plasticity.
Environmental enrichment (EE) is known to profoundly affect the central nervous system (CNS) at the functional, anatomical and molecular level, both during the critical period and during adulthood. ...Recent studies focusing on the visual system have shown that these effects are associated with the recruitment of previously unsuspected neural plasticity processes. At early stages of brain development, EE triggers a marked acceleration in the maturation of the visual system, with maternal behaviour acting as a fundamental mediator of the enriched experience in both the foetus and the newborn. In adult brain, EE enhances plasticity in the cerebral cortex, allowing the recovery of visual functions in amblyopic animals. The molecular substrate of the effects of EE on brain plasticity is multi-factorial, with reduced intracerebral inhibition, enhanced neurotrophin expression and epigenetic changes at the level of chromatin structure. These findings shed new light on the potential of EE as a non-invasive strategy to ameliorate deficits in the development of the CNS and to treat neurological disorders.
Abstract
We present the results of a systematic search and analysis of GRBs detected by the Astrorivelatore Gamma ad Immagini LEggero (AGILE) MiniCALorimeter (MCAL; 0.4–100 MeV) over a time frame of ...13 yr, from 2007 to 2020 November. The MCAL GRB sample consists of 503 bursts triggered by MCAL, 394 of which were fully detected onboard with high time resolution. The sample consists of about 44% short GRBs and 56% long GRBs. In addition, 109 bursts triggered partial MCAL onboard data acquisitions, providing further detections that can be used for joint analyses or triangulations. More than 90% of these GRBs were also detected by the AGILE Scientific RateMeters (RMs), providing simultaneous observations between 20 keV and 100 MeV. We performed spectral analysis of these events in the 0.4–50 MeV energy range. We could fit the time-integrated spectrum of 258 GRBs with a single power-law model, resulting in a mean photon index 〈
β
〉of−2.3. Among them, 43 bursts could also be fitted with a Band model, with peak energy above 400 keV, resulting in a mean low-energy photon index 〈
α
〉 = −0.6, a mean high-energy photon index 〈
β
〉 = −2.5, and a mean peak energy 〈
E
p
〉 = 640 keV. The AGILE MCAL GRB sample mostly consists of hard-spectrum GRBs, with a large fraction of short-duration events. We discuss properties and features of the MCAL bursts, whose detections can be used to perform joint broad-band analysis with other missions, and to provide insights on the high-energy component of the prompt emission in the tens of mega electron volt energy range.
Glial-fibrillary-acidic-protein (GFAP) has recently drawn significant attention from the clinical environment as a promising biomarker. The pathologies which can be linked to the presence of GFAP in ...blood severely affect the human central nervous system. These pathologies are glioblastoma multiforme (GBM), traumatic brain injuries (TBIs), multiple sclerosis (MS), intracerebral hemorrhage (ICH), and neuromyelitis optica (NMO). Here, we develop three different detection strategies for GFAP, among the most popular in the biosensing field and never examined side by side within the experimental frame. We compare their capability of detecting GFAP in a clean-buffer and serum-matrix by using gold-coated quartz-crystal-microbalance (QCM) sensors. All the three detection strategies are based on antibodies, and each of them focuses on a key aspect of the biosensing process. The first is based on a polyethylene glycol (PEG) chain for antifouling, the second on a protein-G linker for controlling antibody-orientation, and the third on antibody-splitting and direct surface immobilization for high-surface coverage. Then, we select the best-performing protocol and validate its detection performance with an ultra-high-frequency (UHF) surface-acoustic-wave (SAW) based lab-on-chip (LoC). GFAP successful detection is demonstrated in a clean-buffer and serum-matrix at a concentration of 35 pM. This GFAP level is compatible with clinical diagnostics. This result suggests the use of our technology for the realization of a point-of-care biosensing platform for the detection of multiple brain-pathology biomarkers.
•GFAP is linked to severe pathologies of the human central nervous system.•GFAP is a promising biomarker that can be found in circulating blood.•Three functionalization approaches for detecting GFAP with biosensors are developed.•The functionalization capability of detecting GFAP is firstly evaluated by QCM.•A new SAW biosensor is used for detecting diagnostic GFAP levels in serum-matrix.
FRB 180916 is a most intriguing source capable of producing repeating fast radio bursts with a periodic 16.3 day temporal pattern. The source is well positioned in a star-forming region in the ...outskirts of a nearby galaxy at 150 Mpc distance. In this Letter we report on the X-ray and γ-ray observations of FRB 180916 obtained by AGILE and Swift. We focused especially on the recurrent 5 day time intervals of enhanced radio bursting. In particular, we report on the results obtained in the time intervals 2020 February 3-8, 2020 February 25, 2020 March 5-10, and 2020 March 22-28 during a multiwavelength campaign involving high-energy and radio observations of FRB 180916. We also searched for temporal coincidences at millisecond timescales between the 32 known radio bursts of FRB 180916 and X-ray and MeV events detectable by AGILE. We do not detect any simultaneous event or any extended X-ray and γ-ray emission on timescales of hours/days/weeks. Our cumulative X-ray (0.3-10 keV) flux upper limit of 5 × 10−14 erg cm−2 s−1 (obtained during 5 day active intervals from several 1-2 ks integrations) translates into an isotropic luminosity upper limit of LX,UL ∼ 1.5 × 1041 erg s−1. Deep γ-ray observations above 100 MeV over a many-year timescale provide an average luminosity upper limit one order of magnitude larger. These results provide the so-far most stringent upper limits on high-energy emission from the FRB 180916 source. Our results constrain the dissipation of magnetic energy from a magnetar-like source of radius Rm, internal magnetic field Bm, and dissipation timescale τd to satisfy the relation , where Rm,6 is Rm in units of 106 cm, Bm,16 is Bm in units of 1016 G, and τd,8 in units of 108 s.
AGILE Observations of Fast Radio Bursts Verrecchia, F.; Casentini, C.; Tavani, M. ...
Astrophysical journal/The Astrophysical journal,
07/2021, Letnik:
915, Številka:
2
Journal Article
Recenzirano
Odprti dostop
Abstract
We report on a systematic search for hard X-ray and
γ
-ray emission in coincidence with fast radio bursts (FRBs) observed by the AGILE satellite. We used 13 yr of AGILE archival data ...searching for time coincidences between exposed FRBs and events detectable by the MCAL (0.4–100 MeV) and GRID (50 MeV–30 GeV) detectors at timescales ranging from milliseconds to days/weeks. The current AGILE sky coverage allowed us to extend the search for high-energy emission preceding and following the FRB occurrence. We considered all FRB sources currently included in catalogs and identified a subsample (15 events) for which a good AGILE exposure with either MCAL or GRID was obtained. In this paper we focus on nonrepeating FRBs, compared to a few nearby repeating sources. We did not detect significant MeV or GeV emission from any event. Our hard X-ray upper limits (ULs) in the MeV energy range were obtained for timescales from submillisecond to seconds, and in the GeV range from minutes to weeks around event times. We focus on a subset of five nonrepeating and two repeating FRB sources whose distances are most likely smaller than that of 180916.J0158+65 (150 Mpc). For these sources, our MeV ULs translate into ULs on the isotropically emitted energy of about 3 × 10
46
erg, comparable to that observed in the 2004 giant flare from the Galactic magnetar SGR 1806–20. On average, these nearby FRBs emit radio pulses of energies significantly larger than the recently detected SGR 1935+2154 and are not yet associated with intense MeV flaring.
Highlights ► EE restores the plasticity of stereoscopic perception after the end of the critical period. ► Long-term sensory deprivation causes a marked deterioration of depth perception. ► EE ...reinstates depth-perception abilities in adult amblyopic animals.
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