Since chemical or pharmacological studies on the propolis of Brazilian native bees are scarce, the aim of this study was to evaluate the chemical profile, the antioxidant, cytotoxic and antibacterial ...activity of aqueous and hydro-alcoholic extracts and isolated compounds of propolis of the native bees, Melipona quadrifasciata and Tetragonisca angustula, against bacteria with (Gram-positive and Gram-negative) and without cell wall (mollicutes). The extracts presented a peculiar feature between green and yellow propolis. Despite the low content of flavonoid and phenolic compounds, a promising level of antioxidant activity without toxicity in the propolis extracts of M. quadrifasciata was observed. The best antimicrobial activity was that of the hydro-alcoholic extract against Mycoplasma pneumoniae and Ureaplasma urealyticum (MIC 125 μg/ml). We isolated two compounds and identified them from the aqueous and hydro-alcoholic extracts as the flavononol sakuranetin and gallic acid. Sakuranetin and gallic acid presented MICs of 50 and 25 μg/ml against Mycoplasma hominis and Mycoplasma genitalium respectively. Propolis from Brazilian native bees may constitute an alternative and undervalued source of compounds with biological activity. The mollicutes are the smallest self-replicating bacteria that constitute a model of cellular and molecular biology studies due to their small genome and restrict biochemical machinery. This is the first report investigating the potential of antibacterial molecules isolated from propolis of Brazilian native bees using this microorganism model. Our results contribute to a better understanding of the chemical and biological properties of these propolis types and provide evidence for its potential medicinal use.
STORM STUDIES IN THE ARCTIC (STAR) Hanesiak, John; Stewart, Ronald; Taylor, Peter ...
Bulletin of the American Meteorological Society,
01/2010, Letnik:
91, Številka:
1
Journal Article
Recenzirano
Odprti dostop
The Storm Studies in the Arctic (STAR) network (2007–2010) conducted a major meteorological field project from 10 October–30 November 2007 and in February 2008, focused on southern Baffin Island, ...Nunavut, Canada—a region that experiences intense autumn and winter storms. The STAR research program is concerned with the documentation, better understanding, and improved prediction of meteorological and related hazards in the Arctic, including their modification by local topography and land–sea ice–ocean transitions, and their effect on local communities. To optimize the applicability of STAR network science, we are also communicating with the user community (northern communities and government sectors). STAR has obtained a variety of surface-based and unique research aircraft field measurements, high-resolution modeling products, and remote sensing measurements (including Cloudsat) as part of its science strategy and has the first arctic Cloudsat validation dataset. In total, 14 research flights were flown between 5 and 30 November 2007, with eight coinciding with Cloudsat passes. The aircraft was outfitted with many instruments that measure cloud microphysical parameters and three unique Doppler-polarized airborne radars operating in Ka, X and W bands. The project area, instrumentation platforms, real-time forecasts, storm cases, and results thus far are discussed in this article. A number of synoptic and mesoscale features were sampled—such as fronts, upslope/terrain-enhanced precipitation, convective precipitation, and boundary layer clouds/precipitation—as well as targeted Cloudsat missions. One significant and unique event included a research flight into an intense high-latitude storm leftover from Hurricane Noel—an intense tropical and extratropical disturbance that caused many fatalities in the tropics and extensive damage on the eastern North American seaboard. These synoptic and mesoscale features and high-latitude storms will be studied in detail over the next several years. It is anticipated that scientific progress in better understanding the nature of these arctic storms and their hazards will lead to improved conceptual models and improved prediction of such events.
The North Water Polynya (NOW) is one of the most productive marine environments in the Arctic. With Arctic sea-ice cover a prominent control in the production of marine organic matter (OM), polynyas ...are likely to be sentinels of the effects of recent change in ice climate. We collected six sediment cores from the NOW, dated them using 210Pb, corroborated with 137Cs where possible, and analysed down-core profiles of OM kerogen (Rock-Eval 6 analysis), total organic carbon (TOC), total organic nitrogen (TON), δ13C and δ15N. The down-core records were examined for evidence of recent (past 150years) change.
Sediment OM bulk concentrations (TOC and TON) displayed exponential decreases with water depth reflecting water-column remineralization processes. Using a model to account for sedimentation rate and sediment surface mixing, we found that cores from the interior of the NOW showed no significant change between pre-1900 sediments and post-1900 sediments, and little variance among cores. In contrast, a core from the northwest boundary of the region showed evidence of increased marine organic carbon input, and two cores from the southeast boundary showed evidence of decreased terrigenous carbon input. In addition, the cores at the southeast boundary, on the slope off Greenland, witnessed a significant decline in sedimentation rate during the same time interval. We interpret the change in OM in the boundary cores in the context of change in regional ice climate and runoff. Our results suggest that the margin of this polynya is more vulnerable to change than the interior, and thus is a better location to seek evidence of change. Furthermore, the diversity of settings within NOW indicates that change must be understood at sub-regional scales.
•Sediment cores show little or no change in organic fluxes in the Northwater polynya.•At the northwest boundary marine organic fluxes have recently increased by ~30%.•At the southeast boundary terrigenous organic carbon fluxes have declined.•The margin of the polynya shows change whereas the interior does not.
GM-CSF (granulocyte-macrophage colony stimulating factor) plays a central role in inflammatory processes. Treatment with antibodies neutralizing murine GM-CSF showed significant therapeutic effects ...in mouse models of inflammatory diseases. We constructed by phage display technology a human scFv, which could potently neutralize human GM-CSF. At first, a human VL repertoire was combined with the VH domain of a parental GM-CSF-neutralizing rat antibody. One dominant rat/human scFv clone was selected, neutralizing human GM-CSF with an IC50 of 7.3 nM. The human VL of this clone was then combined with a human VH repertoire. The latter preserved the CDR 3 of the parental rat VH domain to retain binding specificity. Several human scFvs were selected, which neutralized human GM-CSF at low nanomolar concentrations (IC50 ≥ 2.6 nM). To increase serum half-life, a branched 40 kDa PEG-polymer was coupled to the most potent GM-CSF-neutralizing scFv (3077) via an additional C-terminal cysteine. PEG conjugation had a negligible effect on the in vitro neutralizing potential of the scFv, although it caused a significant drop in binding affinity owing to a reduced on-rate. It also significantly increased the stability of the scFv at elevated temperatures. In mouse experiments, the PEGylated scFv 3077 showed a significantly prolonged elimination half-life of 59 h as compared with 2 h for the unconjugated scFv version. PEGylated scFv 3077 is a potential candidate for development of a novel antibody therapy to treat pro-inflammatory human diseases.
We describe directed searches for continuous gravitational waves from sixteen well localized candidate neutron stars assuming none of the stars has a binary companion. The searches were directed ...toward fifteen supernova remnants and Fomalhaut~b, an extrasolar planet candidate which has been suggested to be a nearby old neutron star. Each search covered a broad band of frequencies and first and second time derivatives. After coherently integrating spans of data from the first Advanced LIGO observing run of 3.5--53.7 days per search, applying data-based vetoes and discounting known instrumental artifacts, we found no astrophysical signals. We set upper limits on intrinsic gravitational wave strain as strict as \(1\times10^{-25}\), on fiducial neutron star ellipticity as strict as \(2\times10^{-9}\), and on fiducial \(r\)-mode amplitude as strict as \(3\times10^{-8}\).
We present results on the mass, spin, and redshift distributions with phenomenological population models using the ten binary black hole mergers detected in the first and second observing runs ...completed by Advanced LIGO and Advanced Virgo. We constrain properties of the binary black hole (BBH) mass spectrum using models with a range of parameterizations of the BBH mass and spin distributions. We find that the mass distribution of the more massive black hole in such binaries is well approximated by models with no more than 1% of black holes more massive than \(45\,M_\odot\), and a power law index of \(\alpha = {1.3}^{+1.4}_{-1.7}\) (90% credibility). We also show that BBHs are unlikely to be composed of black holes with large spins aligned to the orbital angular momentum. Modelling the evolution of the BBH merger rate with redshift, we show that it is at or increasing with redshift with 93% probability. Marginalizing over uncertainties in the BBH population, we find robust estimates of the BBH merger rate density of \(R = {53.2}^{+55.8}_{-28.2}\) Gpc\(^{-3}\) yr\(^{-1}\) (90% credibility). As the BBH catalog grows in future observing runs, we expect that uncertainties in the population model parameters will shrink, potentially providing insights into the formation of black holes via supernovae, binary interactions of massive stars, stellar cluster dynamics, and the formation history of black holes across cosmic time.
Phys. Rev. Lett. 125, 101102 (2020) On May 21, 2019 at 03:02:29 UTC Advanced LIGO and Advanced Virgo observed a
short duration gravitational-wave signal, GW190521, with a three-detector
network ...signal-to-noise ratio of 14.7, and an estimated false-alarm rate of 1
in 4900 yr using a search sensitive to generic transients. If GW190521 is from
a quasicircular binary inspiral, then the detected signal is consistent with
the merger of two black holes with masses of $85^{+21}_{-14} M_{\odot}$ and
$66^{+17}_{-18} M_{\odot}$ (90 % credible intervals). We infer that the primary
black hole mass lies within the gap produced by (pulsational) pair-instability
supernova processes, and has only a 0.32 % probability of being below $65
M_{\odot}$. We calculate the mass of the remnant to be $142^{+28}_{-16}
M_{\odot}$, which can be considered an intermediate mass black hole (IMBH). The
luminosity distance of the source is $5.3^{+2.4}_{-2.6}$ Gpc, corresponding to
a redshift of $0.82^{+0.28}_{-0.34}$. The inferred rate of mergers similar to
GW190521 is $0.13^{+0.30}_{-0.11}\,\mathrm{Gpc}^{-3}\,\mathrm{yr}^{-1}$.
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