826 research outputs found
Using the standard THC unit to regulate THC content in legal cannabis markets [Commentary]
Abstract not available
'Standard THC Units':a proposal to standardise dose across all cannabis products and methods of administration
Background and Aims
Cannabis products are becoming increasingly diverse, and vary considerably in concentrations of ∆9-tetrahydrocannabinol (THC) and cannabidiol (CBD). Higher doses of THC can increase the risk of harm from cannabis, while CBD may partially offset some of these effects. Lower Risk Cannabis Use Guidelines currently lack recommendations based on quantity of use, and could be improved by implementing standard units. However, there is currently no consensus on how units should be measured or standardized among different cannabis products or methods of administration.
Argument
Existing proposals for standard cannabis units have been based on specific methods of administration (e.g. joints) and these may not capture other methods, including pipes, bongs, blunts, dabbing, vaporizers, vape pens, edibles and liquids. Other proposals (e.g. grams of cannabis) cannot account for heterogeneity in THC concentrations among different cannabis products. Similar to alcohol units, we argue that standard cannabis units should reflect the quantity of primary active pharmacological constituents (dose of THC). On the basis of experimental and ecological data, public health considerations and existing policy, we propose that a ‘standard THC unit’ should be fixed at 5 mg THC for all cannabis products and methods of administration. If supported by sufficient evidence in future, consumption of standard CBD units might offer an additional strategy for harm reduction.
Conclusions
Standard ∆9-tetrahydrocannabinol (THC) units can potentially be applied among all cannabis products and methods of administration to guide consumers and promote safer patterns of use
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ISO observations of M8, the Lagoon nebula
In this paper, IRAS, ISO, and molecular line observations of the M8 and M8E sources in the Lagoon Nebula are reported
On the nature of the EXor accretion events: an unfrequent manifestation of a common phenomenology ?
We present the results of a comparison between classical and newly identified
EXor based on literature data and aimed at recognizing possible differences or
similarities of both categories. Optical and near-IR two-color diagrams,
modalities of fluctuations, and derived values of the mass accretion rates are
indicative of strong similarities between the two samples. We demonstrate how
the difference between the outburst and the quiescence spectral energy
distribution of all the EXor can be well fitted with a single blackbody, as if
an additional thermal component appears during the outbursting phase.
Temperatures of this additional component span between 1000 and 4500 K, while
the radii of the emitting regions (assumed to be a uniform disk) span between
0.01 and 0.1 AU, sizes typical of the inner portions of the circumstellar disk.
Spots persisting up to 50% of the outburst duration, not exceeding the 10% of
the stellar surface, and with temperatures compatible with the EXor mass
accretion rates, are able to account for both the appearance of the additional
thermal component and the dust sublimation in the inner structures of the disk.
We also compare the EXor events with the most significant color and magnitude
fluctuations of active T Tauri stars finding that (i} burst accretion phenomena
should also be important for this latter class; (ii} EXor events could be more
frequent then those accidentally discovered. Remarkable is the case of the
source V2493 Cyg, a T Tauri star recently identified as a strong outbursting
object: new optical and near-IR photometric and spectroscopic data are
presented trying to clarify its EXor or FUor nature.Comment: Accepted for publication in Ap
In vitro study on the mechanisms of action of a novel phytotherapeutic compound against human hepatoma cells.
HepG2 human hepatoma cells were incubated for 24 or 48 h with various concentrations of YHK solution. After 24 h incubation, cell proliferation and cytotoxicity were determined by 3-(4,5-dimethylthiazol-2- yl)-5-(3carboxymethoxyphenyl)-2-(4-sulfophenyl)-2Htetrazolium (MTT) assay. Cytotoxicity or necrosis was expressed as lactate dehydrogenase (LDH) release. After exponential growth phase HepG2 cells were treated with different doses of YHK and apoptosis was assessed by using an Annexin V-FITC kit. Further, oxidative stress was measured by dichlorofluorescein-diacetate (DCFH-DA) assay. As compared to control, YHK-treated cultures showed a significant time-course decrease of the proliferation rate of HepG2 cell growth (p < 0.01). This is likely to be due to an enhanced cytotoxicity (MTT and LDH tests) (p < 0.001). On the other hand, YHK showed in vitro to significantly enhance the oxidative stress of HepG2 cell (p < 0.01) while also markedly increasing apoptosis at 72 h with cells G2/M phase arrest (p < 0.01). These data suggest that YHK seem to modulate the extrinsic and intrinsic regulators of apoptosis and sensitize tumour cells to apoptosis. These preliminary data are worth interest when considering that this nutraceutical has been shown in vitro and in vivo to exert protective anti-tumour effect by redox statusmodulating and immuno-regulatory actions. Given its lack of toxicity so far reported, such natural product might represent an effective nutritional supplement i
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Strong H<sub>2</sub>O and high-<i>J</i> CO emission towards the Class 0 protostar L1448-mm
The spectrum of the Class 0 source L1448-mm has been measured over the wavelength range extending from 6 to 190 μm with the Long Wavelength Spectrometer (LWS) and the Short Wavelength Spectrometer (SWS) on the Infrared Space Observatory (ISO). The far infrared spectrum is dominated by strong emission from gaseous H2O and from CO transitions with rotational quantum numbers J ≥ 14; in addition, the H2 pure rotational lines S(3), S(4) and S(5), the OH fundamental line at 119 μm, as well as emission from [O I]63 μm and [C II] 158 μm are also observed. The strong CO and water emission can be consistently explained as originating in a warm gas component at T ~ 700-1400 K and nH2~(3-50) 104cm-3 , which fills about 0.2-2% of the ~ 75" LWS field of view (corresponding, assuming a single emitting region, to a physical size of about (3-12)" or (0.5-2) 10-2 pc at d = 300 pc). We derive an H2O/CO abundance ratio ~ 5, which, assuming a standard CO/H2 abundance of 10-4, corresponds to H2O/H2 ~ 5 10-4. This value implies that water is enhanced by about a factor ~ 103 with respect to its expected abundance in the ambient gas. This is consistent with models of warm shocked regions which predict that most of the free atomic oxygen will be rapidly converted into water once the temperature of the post-shocked gas exceeds ~ 300 K. The relatively high density and compact size inferred for this emission may suggest an origin in the shocked region along the molecular jet traced by SiO and EHV CO millimeter line emission. Further support is given by the fact that the observed enhancement in H2O can be explained by shock conditions similar to those expected to produce the abundant SiO observed in the region. L1448-mm shows the largest water abundance so far observed by ISO amongst young sources displaying outflow activity; we argue that the occurrence of multiple shocks over a relatively short interval of time, like that evidenced in the surroundings of L1448-mm, could have contributed to enrich the molecular jet with a high H2O column density
Evolution of dust and ice features around FU Orionis objects
(abridged) We present spectroscopy data for a sample of 14 FUors and 2 TTauri
stars observed with the Spitzer Space Telescope or with the Infrared Space
Observatory (ISO). Based on the appearance of the 10 micron silicate feature we
define 2 categories of FUors. Objects showing the silicate feature in
absorption (Category 1) are still embedded in a dusty and icy envelope. The
shape of the 10 micron silicate absorption bands is compared to typical dust
compositions of the interstellar medium and found to be in general agreement.
Only one object (RNO 1B) appears to be too rich in amorphous pyroxene dust, but
a superposed emission feature can explain the observed shape. We derive optical
depths and extinction values from the silicate band and additional ice bands at
6.0, 6.8 and 15.2 micron. In particular the analysis of the CO_2 ice band at
15.2 micron allows us to search for evidence for ice processing and constrains
whether the absorbing material is physically linked to the central object or in
the foreground. For objects showing the silicate feature in emission (Category
2), we argue that the emission comes from the surface layer of accretion disks.
Analyzing the dust composition reveals that significant grain growth has
already taken place within the accretion disks, but no clear indications for
crystallization are present. We discuss how these observational results can be
explained in the picture of a young, and highly active accretion disk. Finally,
a framework is proposed as to how the two categories of FUors can be understood
in a general paradigm of the evolution of young, low-mass stars. Only one
object (Parsamian 21) shows PAH emission features. Their shapes, however, are
often seen toward evolved stars and we question the object's status as a FUor
and discuss other possible classifications.Comment: accepted for publication in ApJ; 63 pages preprint style including 8
tables and 24 figure
Near-infrared spectroscopy of EX Lupi in outburst
EX Lup is the prototype of the EXor class of young eruptive stars: objects
showing repetitive brightenings due to increased accretion from the
circumstellar disk to the star. In this paper, we report on medium-resolution
near-infrared spectroscopy of EX\,Lup taken during its extreme outburst in
2008, as well as numerical modeling with the aim of determining the physical
conditions around the star. We detect emission lines from atomic hydrogen,
helium, and metals, as well as first overtone bandhead emission from carbon
monoxide. Our results indicate that the emission lines are originating from gas
located in a dust-free region within ~ 0.2 AU of the star. The profile of the
CO bandhead indicates that the CO gas has a temperature of 2500 K, and is
located in the inner edge of the disk or in the outer parts of funnel flows.
The atomic metals are probably co-located with the CO. Some metallic lines are
fluorescently excited, suggesting direct exposure to ultraviolet photons. The
Brackett series indicates emission from hot (10000 K) and optically thin gas.
The hydrogen lines display a strong spectro-astrometric signal, suggesting that
the hydrogen emission is probably not coming from an equatorial boundary layer;
a funnel flow or disk wind origin is more likely. This picture is broadly
consistent with the standard magnetospheric accretion model usually assumed for
normally accreting T Tauri stars. Our results also set constraints on the
eruption mechanism, supporting a model where material piles up around the
corotation radius and episodically falls onto the star.Comment: 12 pages, 8 figures, 1 table, accepted for publication in Ap
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Molecular line emissions from pre main sequence objects
We present some preliminary results obtained with the LWS G.T. programme on the study of young objects driving molecular outflows. In particular, we discuss the importance of molecular emission in these sources and address the role of the H20 cooling
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