4,602 research outputs found

    Gravitational and electromagnetic emission by magnetized coalescing binary systems

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    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

    Bouncing cosmology in f(R,G)f(R,\mathcal{G}) gravity by order reduction

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    A bouncing universe is a viable candidate to solve the initial singularity problem. Here we consider bouncing solutions in the context of f(R,G)f(R,\mathcal{G}) gravity by using an order reduction technique which allows one to find solutions that are perturbatively close to General Relativity. This procedure also acts as a model selection approach. Indeed, several covariant gravitational actions leading to a bounce are directly selected by demanding that the Friedmann equation derived within such gravity theories coincides with the one emerging from Loop Quantum Cosmology.Comment: v1: 7 pages; v2: 8 pages. Matches published version in Annals of Physic

    UV-B Physiological Changes Under Conditions of Distress and Eustress in Sweet Basil

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    UV-B radiation has been previously reported to induce protective or deleterious effects on plants depending on the UV-B irradiation doses. To elucidate how these contrasting events are physiologically coordinated, we exposed sweet basil plants to two UV-B doses: low (8.5 kJ m-2 day-1, 30 min exposure) and high (68 kJ m-2 day-1, 4 h exposure), with the plants given both doses once continuously in a single day. Physiological tests during and after both UV-B exposures were performed by comparing the stress-induced damage and adverse effects on photosynthetic activity, the concentration and composition of photosynthetic and non-photosynthetic pigments, and stress-related hormones biosynthesis in basil plants. Our results showed that upon receiving a high UV-B dose, a severe inactivation of oxygen evolving complex (OEC) activity at the PSII donor side and irreversible PSII photodamage caused primarily by limitation of the acceptor side occurred, which overloaded protective mechanisms and finally led to the death of the plants. In contrast, low UV-B levels did not induce any signs of UV-B stress injuries. The OEC partial limitation and the inactivation of the electron transport chain allowed the activation of photoprotective mechanisms, avoiding irreversible damage to PSII. Overall results indicate the importance of a specific response mechanisms regulating photoprotection vs irreversible photoinhibition in basil that were modulated depending on the UV-B doses

    Atogepant for the Prevention of Episodic Migraine in Adults: A Systematic Review and Meta-Analysis of Efficacy and Safety

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    Introduction: The inhibition of the calcitonin gene-related peptide (CGRP) pathway has attracted interest in pharmacological research on migraine. Atogepant is a potent, selective, orally available antagonist of the CGRP receptor approved as a preventive treatment of episodic migraine. This systematic review with meta-analysis aims to evaluate the efficacy and safety of atogepant for the prevention of episodic migraine in adult patients. Methods: Randomized, placebo-controlled, single or double-blinded trials were identified through a systematic literature search (December week 4, 2021). Main outcomes included the changes from baseline in monthly migraine days and the incidence of adverse events (AEs) and treatment withdrawal due to AEs. Mean difference (MD) and risk ratio (RR) with 95% confidence intervals (95% CIs) were estimated. Results: Two trials were included, overall enrolling 1550 patients. A total of 408 participants were randomized to placebo, 314 to atogepant 10 mg, 411 to atogepant 30 mg, and 417 to atogepant 60 mg once daily. The mean age of the patients was 41.0 years and 87.7% were women. The reduction in the mean number of migraine days from baseline across the 12-week treatment period was significantly greater among patients treated with atogepant at either the daily dose of 10 mg (MD − 1.16, 95% CI − 1.60 to − 0.73, p < 0.001), 30 mg (MD − 1.15, 95% CI − 1.54 to − 0.76, p < 0.001), or 60 mg (MD − 1.20, 95% CI − 2.18 to − 0.22, p = 0.016) than with placebo. There were no differences in the occurrence of AEs and drug withdrawal due to AEs between atogepant and placebo groups. Constipation was more commonly observed in patients treated with atogepant at 30 mg/day than placebo (RR 5.19, 95% CI 2.00–13.46; p = 0.001). Treatment with atogepant at the daily dose of 60 mg was associated with a higher risk of constipation (RR 4.92, 95% CI 1.89–12.79; p = 0.001) and nausea (RR 2.73, 95% CI 1.47–5.06; p = 0.001) than placebo. Conclusion: Atogepant is an efficacious and overall well-tolerated treatment for the prevention of episodic migraine in adults

    Her2 signaling and breast cancer stem cells: The bridge behind her2-positive breast cancer aggressiveness and therapy refractoriness

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    HER2 overexpression/amplification occurs in 15–20% of breast cancers (BCs) and identifies a highly aggressive BC subtype. Recent clinical progress has increased the cure rates of limited-stage HER2-positive BC and significantly prolonged overall survival in patients with advanced disease; however, drug resistance and tumor recurrence remain major concerns. Therefore, there is an urgent need to increase knowledge regarding HER2 biology and implement available treatments. Cancer stem cells (CSCs) represent a subset of malignant cells capable of unlimited self-renewal and differentiation and are mainly considered to contribute to tumor onset, aggressiveness, metastasis, and treatment resistance. Seminal studies have highlighted the key role of altered HER2 signaling in the maintenance/enrichment of breast CSCs (BCSCs) and elucidated its bidirectional communication with stemness-related pathways, such as the Notch and Wingless/β-catenin cascades. d16HER2, a splice variant of full-length HER2 mRNA, has been identified as one of the most oncogenic HER2 isoform significantly implicated in tumorigenesis, epithelial-mesenchymal transition (EMT)/stemness and the response to targeted therapy. In addition, expression of a heterogeneous collection of HER2 truncated carboxy-terminal fragments (CTFs), collectively known as p95HER2, identifies a peculiar subgroup of HER2-positive BC with poor prognosis, with the p95HER2 variants being able to regulate CSC features. This review provides a comprehensive overview of the current evidence regarding HER2-/d16HER2-/p95HER2-positive BCSCs in the context of the signaling pathways governing their properties and describes the future prospects for targeting these components to achieve long-lasting tumor control

    Ceruloplasmin/Transferrin Ratio Changes in Alzheimer's Disease

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    The link between iron and Alzheimer's disease (AD) has been mainly investigated with a focus on the local accumulation of this metal in specific areas of the brain that are critical for AD. In the present study, we have instead looked at systemic variations of markers of iron metabolism. We measured serum levels of iron, ceruloplasmin, and transferrin and calculated the transferrin saturation and the ceruloplasmin to transferrin ratio (Cp/Tf). Cp/Tf and transferrin saturation increased in AD patients. Cp/Tf ratios also correlated positively with peroxide levels and negatively with serum iron concentrations. Elevated values of ceruloplasmin, peroxides, and Cp/Tf inversely correlated with MMSE scores. Isolated medial temporal lobe atrophy positively correlated with Cp/Tf and negatively with serum iron. All these findings indicate that the local iron accumulation found in brain areas critical for AD should be viewed in the frame of iron systemic alterations

    The Distribution of Mass in the Orion Dwarf Galaxy

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    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

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    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
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