Ultrassonografia duplex Doppler transcraniana em cães com hidrocefalia

Transcranial duplex Doppler ultrasound was performed in 32 conscious dogs presenting ventriculomegaly detected in B-mode, obtaining measures of lateral ventricles and resistance parameters of main cerebral arteries before and after 30 days of clinical treatment. The animals were distributed divided in two groups: group 1, dogs that presented remission or decrease of the neurological signs of the disease after clinical therapy; and group 2, dogs that displayed worsening of the neurological signs or clinical stability. The data were all presented in tables and were submitted to paired t test and to logistic regression models to evaluate the influence of the RI reduction on both groups. There was no significant influence of the variables in the B-mode. After the treatment, the mean resistive index (RI) was significantly lower for the group that presented clinical improvement. There was no significant difference of the mean RI reduction for the same artery when the right and left sides were compared. It could be concluded that transcranial duplex Doppler ultrasound is a method of cerebral hemodynamic assessment able to monitor more precisely the treatment of hydrocephalus in dogs and verify the responses.Foi realizada a ultrassonografia duplex Doppler transcraniana em 32 cães, conscientes, que apresentavam ventriculomegalia previamente detectada ao exame modo-B, para obter as medidas dos ventrículos laterais e os parâmetros de resistência das artérias cerebrais antes e depois de 30 dias de tratamento clínico. Os animais foram distribuídos em dois grupos: 1 - formado por cães que apresentaram remissão ou diminuição dos sinais clínicos após tratamento; 2 - por cães que apresentaram piora dos sinais neurológicos ou estabilidade do quadro clínico. Todos os dados foram dispostos em tabelas e submetidos ao teste t pareado e a modelos de regressão logística para avaliar a influência da redução do índice de resistividade (IR). Não foi observada influência das variáveis em modo-B. Após o tratamento, a média do IR foi significantemente menor para o grupo que apresentou melhora clínica; não houve diferença significativa da média de redução do IR para a mesma artéria quando comparados os lados direito e esquerdo. Concluiu-se que o duplex Doppler transcraniano é um métodos de avaliação hemodinâmica capaz de monitorar mais precisamente o tratamento da hidrocefalia em cães e verificar a resposta dos pacientes

Cosmic Chronometers: Constraining the Equation of State of Dark Energy. I: H(z) Measurements

We present new determinations of the cosmic expansion history from red-envelope galaxies. We have obtained for this purpose high-quality spectra with the Keck-LRIS spectrograph of red-envelope galaxies in 24 galaxy clusters in the redshift range 0.2 < z < 1.0. We complement these Keck spectra with high-quality, publicly available archival spectra from the SPICES and VVDS surveys. We improve over our previous expansion history measurements in Simon et al. (2005) by providing two new determinations of the expansion history: H(z) = 97 +- 62 km/sec/Mpc at z = 0.5 and H(z) = 90 +- 40 km/sec/Mpc at z = 0.8. We discuss the uncertainty in the expansion history determination that arises from uncertainties in the synthetic stellar-population models. We then use these new measurements in concert with cosmic-microwave-background (CMB) measurements to constrain cosmological parameters, with a special emphasis on dark-energy parameters and constraints to the curvature. In particular, we demonstrate the usefulness of direct H(z) measurements by constraining the dark- energy equation of state parameterized by w0 and wa and allowing for arbitrary curvature. Further, we also constrain, using only CMB and H(z) data, the number of relativistic degrees of freedom to be 4 +- 0.5 and their total mass to be < 0.2 eV, both at 1-sigma.Comment: Submitted to JCA

Microwave pyrolysis of Laminaria digitata to produce unique seaweed-derived bio-oils

Microwave pyrolysis has become an attractive form of processing technology to generate bio-oil, bio-char and syngas from different biomass feedstocks. In this study, microwave pyrolysis was performed on the UK native seaweed Laminaria digitata and its extract residue from a bio-refinery process. Pyrolysis of these two feedstocks was successfully achieved without the requirement of microwave susceptors, as pelletizing the biomass was sufficient to allow microwave pyrolysis to occur. It was found that average energy requirements as low as 1.84–2.83 kJ g−1 were required to pyrolyse 55–70% of both feedstocks and bio-oil yields of 5–8% and 10–14% for native and extraction residue L. digitata were produced, respectively. Maximum microwave pyrolysis processing times were in the order of 200 s. The bio-oil generated from both feedstocks contained no phenolic based compounds, but a greater number of nitrogen-containing compounds and compounds derived from macroalgal polysaccharides. Yields of certain compounds differed in bio-oils generated from the two L. digitata feedstocks, however it was observed that specific energy did not have a direct influence on bio-oil compound yield. Furthermore, the identification of a particular nitrogen-containing compound L-Proline, 1-methyl-5-oxo-, methylester is thought to be a unique product of microwave pyrolysis when carbon-based additives are avoided

The action of all-trans-retinoic acid (ATRA) and synthetic retinoid analogues (EC19 and EC23) on human pluripotent stem cells differentiation investigated using single cell infrared microspectroscopy

All trans-retinoic acid (ATRA) is widely used to direct the differentiation of cultured stem cells. When exposed to the pluripotent human embryonal carcinoma (EC) stem cell line, TERA2.cl.SP12, ATRA induces ectoderm differentiation and the formation of neuronal cell types. We have previously generated synthetic analogues of retinoic acid (EC23 and EC19) which also induce the differentiation of EC cells. Even though EC23 and EC19 have similar chemical structures, they have differing biochemical effects in terms of EC cell differentiation. EC23 induces neuronal differentiation in a manner similar to ATRA, whereas EC19 directs the cells to form epithelial-like derivatives. Previous MALDI-TOF MS analysis examined the response of TERA2.cl.SP12 cells after exposure to ATRA, EC23 and EC19 and further demonstrated the similarly in the effect of ATRA and EC23 activity whilst responses to EC19 were very different. In this study, we show that Fourier Transform Infrared Micro-Spectroscopy (FT-IRMS) coupled with appropriate scatter correction and multivariate analysis can be used as an effective tool to further investigate the differentiation of human pluripotent stem cells and monitor the alternative affects different retinoid compounds have on the induction of differentiation. FT-IRMS detected differences between cell populations as early as 3 days of compound treatment. Populations of cells treated with different retinoid compounds could easily be distinguished from one another during the early stages of cell differentiation. These data demonstrate that FT-IRMS technology can be used as a sensitive screening technique to monitor the status of the stem cell phenotype and progression of differentiation along alternative pathways in response to different compounds

Spin structure of the nucleon: QCD evolution, lattice results and models

The question how the spin of the nucleon is distributed among its quark and gluon constituents is still a subject of intense investigations. Lattice QCD has progressed to provide information about spin fractions and orbital angular momentum contributions for up- and down-quarks in the proton, at a typical scale \mu^2~4 GeV^2. On the other hand, chiral quark models have traditionally been used for orientation at low momentum scales. In the comparison of such model calculations with experiment or lattice QCD, fixing the model scale and the treatment of scale evolution are essential. In this paper, we present a refined model calculation and a QCD evolution of lattice results up to next-to-next-to-leading order. We compare this approach with the Myhrer-Thomas scenario for resolving the proton spin puzzle.Comment: 11 pages, 6 figures, equation (9) has been corrected leading to a revised figure 1b. Revision matches published versio

Perturbative and nonperturbative contributions to the strange quark asymmetry in the nucleon

There are two mechanisms for the generation of an asymmetry between the strange and anti-strange quark distributions in the nucleon: nonperturbative contributions originating from nucleons fluctuating into virtual baryon-meson pairs such as $\Lambda K$ and $\Sigma K$, and perturbative contributions arising from gluons splitting into strange and anti-strange quark pairs. While the nonperturbative contributions are dominant in the large-$x$ region, the perturbative contributions are more significant in the small-$x$ region. We calculate this asymmetry taking into account both nonperturbative and perturbative contributions, thus giving a more accurate evaluation of this asymmetry over the whole domain of $x$. We find that the perturbative contributions are generally a few times larger in magnitude than the nonperturbative contributions, which suggests that the best region to detect this asymmetry experimentally is in the region $0.02 < x < 0.03$. We find that the asymmetry may have more than one node, which is an effect that should be taken into account, e.g. for parameterizations of the strange and anti-strange quark distributions used in global analysis of parton distributions.Comment: 14 pages, 4 figures, figures comparing theoretical calculations with NNPDF global analysis added, accepted for publication in EPJ

Non-Invasive Mouse Models of Post-Traumatic Osteoarthritis

SummaryAnimal models of osteoarthritis (OA) are essential tools for investigating the development of the disease on a more rapid timeline than human OA. Mice are particularly useful due to the plethora of genetically modified or inbred mouse strains available. The majority of available mouse models of OA use a joint injury or other acute insult to initiate joint degeneration, representing post-traumatic osteoarthritis (PTOA). However, no consensus exists on which injury methods are most translatable to human OA. Currently, surgical injury methods are most commonly used for studies of OA in mice; however, these methods may have confounding effects due to the surgical/invasive injury procedure itself, rather than the targeted joint injury. Non-invasive injury methods avoid this complication by mechanically inducing a joint injury externally, without breaking the skin or disrupting the joint. In this regard, non-invasive injury models may be crucial for investigating early adaptive processes initiated at the time of injury, and may be more representative of human OA in which injury is induced mechanically. A small number of non-invasive mouse models of PTOA have been described within the last few years, including intra-articular fracture of tibial subchondral bone, cyclic tibial compression loading of articular cartilage, and anterior cruciate ligament (ACL) rupture via tibial compression overload. This review describes the methods used to induce joint injury in each of these non-invasive models, and presents the findings of studies utilizing these models. Altogether, these non-invasive mouse models represent a unique and important spectrum of animal models for studying different aspects of PTOA

Thin accretion disc with a corona in a central magnetic field

We study the steady-state structure of an accretion disc with a corona surrounding a central, rotating, magnetized star. We assume that the magneto-rotational instability is the dominant mechanism of angular momentum transport inside the disc and is responsible for producing magnetic tubes above the disc. In our model, a fraction of the dissipated energy inside the disc is transported to the corona via these magnetic tubes. This energy exchange from the disc to the corona which depends on the disc physical properties is modified because of the magnetic interaction between the stellar magnetic field and the accretion disc. According to our fully analytical solutions for such a system, the existence of a corona not only increases the surface density but reduces the temperature of the accretion disc. Also, the presence of a corona enhances the ratio of gas pressure to the total pressure. Our solutions show that when the strength of the magnetic field of the central neutron star is large or the star is rotating fast enough, profiles of the physical variables of the disc significantly modify due to the existence of a corona.Comment: Accepted for publication in Astrophysics & Space Scienc

Shorter alkyl chains enhance molecular diffusion and electron transfer kinetics between photosensitisers and catalysts in CO2-reducing photocatalytic liposomes

Covalent functionalisation with alkyl tails is a common method for supporting molecular catalysts and photosensitisers onto lipid bilayers, but the influence of the alkyl chain length on the photocatalytic performances of the resulting liposomes is not well understood. In this work, we first prepared a series of rhenium-based CO2-reduction catalysts [Re(4,4'-(CnH2n+1)(2)-bpy)(CO)(3)Cl] (ReCn; 4,4'-(CnH2n+1)(2)-bpy=4,4'-dialkyl-2,2'-bipyridine) and ruthenium-based photosensitisers [Ru(bpy)(2)(4,4'-(CnH2n+1)(2)-bpy)](PF6)(2) (RuCn) with different alkyl chain lengths (n=0, 9, 12, 15, 17, and 19). We then prepared a series of PEGylated DPPC liposomes containing RuCn and ReCn, hereafter noted C-n, to perform photocatalytic CO2 reduction in the presence of sodium ascorbate. The photocatalytic performance of the C-n liposomes was found to depend on the alkyl tail length, as the turnover number for CO (TON) was inversely correlated to the alkyl chain length, with a more than fivefold higher CO production (TON=14.5) for the C-9 liposomes, compared to C-19 (TON=2.8). Based on immobilisation efficiency quantification, diffusion kinetics, and time-resolved spectroscopy, we identified the main reason for this trend: two types of membrane-bound RuCn species can be found in the membrane, either deeply buried in the bilayer and diffusing slowly, or less buried with much faster diffusion kinetics. Our data suggest that the higher photocatalytic performance of the C-9 system is due to the higher fraction of the more mobile and less buried molecular species, which leads to enhanced electron transfer kinetics between RuC9 and ReC9.Metals in Catalysis, Biomimetics & Inorganic Material