3,608 research outputs found
Binary Neutron Star Merger Remnants as Sources of Cosmic Rays Below the "Ankle"
We investigate non-thermal electron and nuclei energy losses within the
binary neutron star merger remnant produced by the event GW170817. The lack of
a cooling feature within the detected synchrotron emission from the source is
used to constrain the magnetic field at the mG level, assuming that this
emission is electron synchrotron in origin, and that the accelerated spectrum
in the electrons follows the form . The level of
subsequent gamma-ray emission from the source is demonstrated to provide a
further constraint on the source magnetic field strength. We also put forward
alternative strong (G) magnetic field scenarios able to support this
emission. For such stronger fields, the photo-disintegration of non-thermal
nuclei within the source is considered, and a bottleneck period of 5-30
days is found when this process peaks. We find that this class of source is in
principle able to support the population of cosmic rays detected at Earth below
the "ankle".Comment: Accepted for publication in Astropart. Phy
Birationality of \'etale morphisms via surgery
We use a counting argument and surgery theory to show that if is a
sufficiently general algebraic hypersurface in , then any local
diffeomorphism of simply connected manifolds which is a
-sheeted cover away from has degree or (however all
degrees are possible if fails to be a local diffeomorphism at even
a single point). In particular, any \'etale morphism of
algebraic varieties which covers away from such a hypersurface must be
birational.Comment: 17 pages. Replaced to add further references and make language more
consistent with the literatur
The Amyloid-Tau-Neuroinflammation Axis in the Context of Cerebral Amyloid Angiopathy
Cerebral amyloid angiopathy (CAA) is typified by the cerebrovascular deposition of amyloid. Currently, there is no clear understanding of the mechanisms underlying the contribution of CAA to neurodegeneration. Despite the fact that CAA is highly associated with the accumulation of Aβ, other types of amyloids have been shown to associate with the vasculature. Interestingly, in many cases, vascular amyloidosis has been associated with an active immune response and perivascular deposition of hyperphosphorylated tau. Despite the fact that in Alzheimer’s disease (AD) a major focus of research has been the understanding of the connection between parenchymal amyloid plaques, tau aggregates in the form of neurofibrillary tangles (NFTs), and immune activation, the contribution of tau and neuroinflammation to neurodegeneration associated with CAA remains understudied. In this review, we discussed the existing evidence regarding the amyloid diversity in CAA and its relation to tau pathology and immune response, as well as the possible contribution of molecular and cellular mechanisms, previously associated with parenchymal amyloid in AD and AD-related dementias, to the pathogenesis of CAA. The detailed understanding of the “amyloid-tau-neuroinflammation” axis in the context of CAA could open the opportunity to develop therapeutic interventions for dementias associated with CAA that are currently being proposed for AD and AD-related dementias
The incidence, clearance and persistence of non-cervical human papillomavirus infections: a systematic review of the literature
Background: Human papillomavirus (HPV) vaccines were designed to prevent cervical cancer in women and their provision remains a major public health need. However, HPV is also a major cause of non-cervical anogenital and oropharyngeal cancers and the potential benefit of vaccination likely extends beyond cervical cancer. Methods: A systematic literature search of PubMed (1995-2014) identified publications assessing the incidence, persistence, and clearance of non-cervical anogenital/oral HPV infections. Comparability with cervical HPV was assessed by identifying articles assessing the same or similar populations. Results: Available data suggest high incidence rates of non-cervical HPV infection in men and women, with HPV-16 predominating in all sites. The incidence of high risk HPV per 100 person-years ranged from 11.4 to 72.9 for penile infections, 6.7-47.9 at other male genital sites, and 4.4-36.7 and 5.3-23.4 for anal infections in men and women, respectively. The incidence per 100 person-years of oral infection with any HPV type ranged from 5.7 to 6.7 in men and 6.8-39.6 in women. Within the limitations of the data, there was a general pattern of higher incidence and clearance of non-cervical genital HPV infections, compared to cervical infections. HIV status, circumcision, number of sex partners and partner HPV status significantly influenced high-risk HPV incidence/clearance at male anogenital sites. Few studies assessed risk factors for oral HPV. Conclusions: Parallels appear to exist between the epidemiology of cervical and non-cervical HPV infections in terms of incidence, HPV-type distribution, and risk factors for infection. Available data suggest that non-cervical genital HPV infections may occur more frequently, with higher clearance rates, than cervical infections. More extensive studies could provide useful information for estimating vaccine impact, the wider cost-benefit of HPV vaccination, and guiding vaccination policy
The Neuroinflammatory Response Associated to Cerebral Amyloid Angiopathy (CAA)
Indiana University-Purdue University Indianapolis (IUPUI)Cerebral amyloid angiopathy (CAA) is characterized by the cerebrovascular deposition of amyloid. The mechanisms underlying the contribution of CAA to neurodegeneration are not fully understood. In this dissertation, there are three main chapters. The first chapter investigates existing evidence regarding the amyloid diversity in CAA and its relation to tau pathology and immune response, as well as the possible contribution of molecular and cellular mechanisms, previously associated with parenchymal amyloid in Alzheimer disease (AD) and AD-related dementias, to the pathogenesis of CAA. The second chapter demonstrates differential glial reactivity and activation associated with early-stage CAA in a mouse model of Familial Danish Dementia (FDD), a neurodegenerative disease characterized by vascular accumulation of Danish amyloid (ADan). We show that early-stage CAA is associated with dysregulation in immune response networks and lipid processing, severe astrogliosis with a neurotoxic A1-astrocytic phenotype, characterized by increased expression of Complement Component 3 (C3), and decreased levels of Triggering Receptor Expressed On Myeloid Cells 2 (Trem2) with no significant reactive microgliosis. Our results also indicate how cholesterol accumulation and Apolipoprotein E (ApoE) are associated with vascular amyloid deposits at the early stages of pathology. Furthermore, we demonstrate A1 astrocytic mediation of Trem2 and microglia homeostasis. In the final chapter, we addressed whether inflammatory stimulus of other cell types are capable of inducing a subtype of neurotoxic astrocytes. Here we show a subtype of C3+ neurotoxic astrocyte are induced by activated endothelial cells that is distinct from astrocytes classically activated by microglia. We show that endothelial activated astrocytes have upregulated expression of A1-astrocytic genes and exhibit a distinctive extracellular matrix remodeling profile. Finally, we demonstrate that endothelial activated astrocytes are Decorin-positive and are associated to vascular amyloid deposits but not parenchymal amyloid plaques in mouse models and AD/CAA patients. These findings show the existence of potentially extensive and subtle functional diversity of C3+-reactive astrocytes
Causal explanation for observed superluminal behavior of microwave propagation in free space
In this paper we present a theoretical analysis of an experiment by Mugnai
and collaborators where superluminal behavior was observed in the propagation
of microwaves. We suggest that what was observed can be well approximated by
the motion of a superluminal X wave. Furthermore the experimental results are
also explained by the so called scissor effect which occurs with the
convergence of pairs of signals coming from opposite points of an annular
region of the mirror and forming an interference peak on the intersection axis
traveling at superluminal speed. We clarify some misunderstandings concerning
this kind of electromagnetic wave propagation in vacuum.Comment: 9 pages, 3 figures, accepted for publication in Physics Letters
Synthesis of xylitan derivatives and preliminary evaluation of in vitro trypanocidal activity
A series of novel xylitan derivatives derived from xylitol were synthesized using operationally simple procedures. A xylitan acetonide was the key intermediate used to prepare benzoate, arylsulfonate esters and 1,2,3-triazole derivatives of xylitan. These compounds were evaluated for their in vitro anti-Trypanosoma cruzi activity against trypomastigote and amastigote forms of the parasite in T. cruzi-infected cell lineages. Benznidazole was used as positive control against T. cruzi and cytotoxicity was determined in mammalian L929 cells. The arylsulfonate xylitan derivative bearing a nitro group displayed the best activity of all the compounds tested, and was slightly more potent than the reference drug benznidazole. The importance of the isopropylidene ketal moiety was established and the greater lipophilicity of these compounds suggests enhancement in cell penetration2110CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE MINAS GERAIS - FAPEMIG473461/2013-7CEX-RED-00010-1
Properties and units in the clinical laboratory sciences part XXIV. Properties and units in clinical molecular genetics (IUPAC Technical Report)
This document describes the application of the syntax, semantic rules, and format of the Nomenclature for Properties and Units (NPU) terminology for coded dedicated kinds-of-property in the subject field of clinical molecular genetics. A vocabulary for NPU definitions in this field, based on international terminology and nomenclature, is introduced and examples of actual NPU definitions for different types of investigations are given and explained
Cooperative secretions facilitate host range expansion in bacteria
The majority of emergent human pathogens are zoonotic in origin, that is, they can transmit to humans from other animals. Understanding the factors underlying the evolution of pathogen host range is therefore of critical importance in protecting human health. There are two main evolutionary routes to generalism: organisms can tolerate multiple environments or they can modify their environments to forms to which they are adapted. Here we use a combination of theory and a phylogenetic comparative analysis of 191 pathogenic bacterial species to show that bacteria use cooperative secretions that modify their environment to extend their host range and infect multiple host species. Our results suggest that cooperative secretions are key determinants of host range in bacteria, and that monitoring for the acquisition of secreted proteins by horizontal gene transfer can help predict emerging zoonoses
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