5,445 research outputs found
Novel treatment strategies for chronic kidney disease: insights from the animal kingdom
Many of the >2 million animal species that inhabit Earth have developed survival mechanisms that aid in the prevention of obesity, kidney disease, starvation, dehydration and vascular ageing; however, some animals remain susceptible to these complications. Domestic and captive wild felids, for example, show susceptibility to chronic kidney disease (CKD), potentially linked to the high protein intake of these animals. By contrast, naked mole rats are a model of longevity and are protected from extreme environmental conditions through mechanisms that provide resistance to oxidative stress. Biomimetic studies suggest that the transcription factor nuclear factor erythroid 2-related factor 2 (NRF2) offers protection in extreme environmental conditions and promotes longevity in the animal kingdom. Similarly, during months of fasting, immobilization and anuria, hibernating bears are protected from muscle wasting, azotaemia, thrombotic complications, organ damage and osteoporosis - features that are often associated with CKD. Improved understanding of the susceptibility and protective mechanisms of these animals and others could provide insights into novel strategies to prevent and treat several human diseases, such as CKD and ageing-associated complications. An integrated collaboration between nephrologists and experts from other fields, such as veterinarians, zoologists, biologists, anthropologists and ecologists, could introduce a novel approach for improving human health and help nephrologists to find novel treatment strategies for CKD
Symmetric hyperbolic systems for Bianchi equations
We obtain a family of first-order symmetric hyperbolic systems for the
Bianchi equations. They have only physical characteristics: the light cone and
timelike hypersurfaces. In the proof of the hyperbolicity, new positivity
properties of the Bel tensor are used.Comment: latex, 7 pages, accepted for publication in Class. Quantum Gra
Entangled networks, synchronization, and optimal network topology
A new family of graphs, {\it entangled networks}, with optimal properties in
many respects, is introduced. By definition, their topology is such that
optimizes synchronizability for many dynamical processes. These networks are
shown to have an extremely homogeneous structure: degree, node-distance,
betweenness, and loop distributions are all very narrow. Also, they are
characterized by a very interwoven (entangled) structure with short average
distances, large loops, and no well-defined community-structure. This family of
nets exhibits an excellent performance with respect to other flow properties
such as robustness against errors and attacks, minimal first-passage time of
random walks, efficient communication, etc. These remarkable features convert
entangled networks in a useful concept, optimal or almost-optimal in many
senses, and with plenty of potential applications computer science or
neuroscience.Comment: Slightly modified version, as accepted in Phys. Rev. Let
Dark Interactions and Cosmological Fine-Tuning
Cosmological models involving an interaction between dark matter and dark
energy have been proposed in order to solve the so-called coincidence problem.
Different forms of coupling have been studied, but there have been claims that
observational data seem to narrow (some of) them down to something annoyingly
close to the CDM model, thus greatly reducing their ability to deal
with the problem in the first place. The smallness problem of the initial
energy density of dark energy has also been a target of cosmological models in
recent years. Making use of a moderately general coupling scheme, this paper
aims to unite these different approaches and shed some light as to whether this
class of models has any true perspective in suppressing the aforementioned
issues that plague our current understanding of the universe, in a quantitative
and unambiguous way.Comment: 13 pages, 9 figures, accepted for publication in JCAP. Minor
corrections, one figure replaced, references adde
On the effect of variable identification on the essential arity of functions
We show that every function of several variables on a finite set of k
elements with n>k essential variables has a variable identification minor with
at least n-k essential variables. This is a generalization of a theorem of
Salomaa on the essential variables of Boolean functions. We also strengthen
Salomaa's theorem by characterizing all the Boolean functions f having a
variable identification minor that has just one essential variable less than f.Comment: 10 page
Avaliação do extrato etanólico de Ottonia martiana Miq. para o controle de duas doenças florestais.
MetabĂłlitos secundĂĄrios presentes em plantas medicinais apresentam vĂĄrias propriedades biolĂłgicas incluindo a atividade antifĂșngica. Esse estudo avaliou o potencial antifĂșngico da planta medicinal Ottonia martiana no controle da pinta-preta em erva-mate (Ilex paraguariensis) e do mofo-cinzento em eucalipto (Eucalyptus dunnii). Extrato etanĂłlico (EBEtOH) dos ĂłrgĂŁos totais (raĂzes, caules, folhas e frutos) foi preparado e testado na concentração de 1000 ?g mL-1 contra os patĂłgenos Cylindrocladium spathulatum (pinta-preta) e Botrytis cinerea (mofo-cinzento). Bioensaios in vitro (germinação de esporos e bioautografia direta) e in vivo (teste de patogenicidade em mudas) mostraram que o EBEtOH reduziu o crescimento micelial dos patĂłgenos testados e a germinação dos esporos de C. spathulatum e estimulou a germinação de esporos de B. cinerea. O teste de patogenicidade mostrou que o controle da pinta-preta em erva-mate e do mofo cinzento em eucalipto nĂŁo Ă© viĂĄvel usando-se a concentração testada de EBEtOH de O. martiana. Na bioautografia direta, foram detectadas zonas de inibição de crescimento micelial dos fungos e que foram relacionadas com a presença de piperovatina
The African hind's (Cephalopholis taeniops, serranidae) use of artificial reefs off Sal Island (Cape Verde): a preliminary study based on acoustic telemetry
The African hind Cephalopholis taeniops (Valenciennes, 1828) is one of the most important commercial demersal species caught in the Cape Verde archipelago. The species is closely associated with hard substrate and is one of the main attractions for SCUBA divers. In January 2006 a former Soviet fishing vessel - the Kwarcit - was sunk off Santa Maria Bay (Sal Island). Young C. taeniops are commonly observed in this artificial reef (AR). In order to investigate the species' use of the AR, 4 specimens were captured and surgically implanted underwater with Vemco brand acoustic transmitters. The fish were monitored daily with an active telemetry receiver for one week after release. Simultaneously, an array of 3 passive VR2 / VR2W receivers was set for 63 days, registering data that allowed an analysis of spatial, daily and short term temporal activity patterns. The results showed site fidelity to the AR, with no migrations to the nearby natural reef. The method used allowed to register a consistent higher activity during daytime and a preference for the area opposite the dominant current
Atividade antifĂșngica in vivo do extrato bruto da Lobelia langeana DusĂ©n, Campanelaceae, frente a um patĂłgeno da erva-mate (Ilex paraguariensis St. Hil.).
Dentre as espĂ©cies vegetais da flora nativa brasileira, encontra-se a Lobelia langeana DusĂ©n, erva comum nos estados do ParanĂĄ e Santa Catarina, conhecida como âlobĂ©liaâ. Esta planta possui vĂĄrias propriedades terapĂȘuticas, inclusive a de substituto do tabaco. Um estudo foi desenvolvido para determinar sua fungitoxicidade, para participar de mĂ©todos alternativos de controle de fitopatĂłgenos. Neste ensaio preliminar, avaliou-se o efeito de um extrato bruto da lobĂ©lia sobre a formação de lesĂ”es foliares causadas por Cylindrocladium spathulatum, em folhas destacadas de erva-mate. O extrato da lobĂ©lia inibiu em 48,9 % o desenvolvimento das lesĂ”es foliares. Este resultado mostrou que o extrato desta planta pode ser testado para o controle da pinta-preta da erva-mate, em condiçÔes de campo
Testing the non-unitarity of the leptonic mixing matrix at FASER
The FASER experiment has detected the first neutrino events coming from LHC.
Near future high-statistic neutrino samples will allow us to search for new
physics within the neutrino sector. Motivated by the forthcoming promising
FASER neutrino data, we study its potential for testing the unitarity of the
neutrino lepton mixing matrix. Although it would be challenging for FASER to
have strong constraints on this kind of new physics, we discuss its role in
contributing to a future improved global analysis.Comment: 8 pages, 1 figure, preprin
Bioautography to assess antibacterial activity of Ottonia martiana Miq. (Piperaceae) on the human oral microbiota.
Ottonia martiana Miq. (Piperaceae), a plant known popularly in southern Brazil as âanestĂ©siaâ and used in the treatment of odontalgia for its anesthetic action on the oral mucosa, was investigated for antibacterial activity by paper disc agar diffusion and bioautographic methods, against microorganisms present in the human oral cavity [Streptococcus mutans (ATCC 25175), Streptococcus mitis (ATCC 49456), Streptococcus pyogenes (ATCC 19615), Streptococcus salivarius (ATCC 25975), Escherichia coli (ATCC 11229 and 25922), Pseudomonas aeruginosa (ATCC 27853) and Enterobacter aerogenes (ATCC 27853).The crude extract of O. martiana (32.9 mg mL-1) had antibacterial potential against all Gram-positive bacteria tested. Analysis of the bioautograms led to the detection of bioactive substances, among which it was possible to identify piperovatine (Rf 0.35), piperlonguminine (Rf 0.52) and isopiperlonguminine (Rf 0.52). The piperovatine and isopiperlonguminine were isolated from the roots of O. martiana, guided by a bioautographic antibacterial bioassay
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