433 research outputs found
Toxicological screening and DNA sequencing detects contamination and adulteration in regulated herbal medicines and supplements for diet, weight loss and cardiovascular health
Use of herbal medicines and supplements by consumers to prevent or treat disease, particularly chronic conditions continues to grow, leading to increased awareness of the minimal regulation standards in many countries. Fraudulent, adulterated and contaminated herbal and traditional medicines and dietary supplements are a risk to consumer health, with adverse effects and events including overdose, drug-herb interactions and hospitalisation. The scope of the risk has been difficult to determine, prompting calls for new approaches, such as the combination of DNA metabarcoding and mass spectrometry used in this study. Here we show that nearly 50% of products tested had contamination issues, in terms of DNA, chemical composition or both. Two samples were clear cases of pharmaceutical adulteration, including a combination of paracetamol and chlorpheniramine in one product and trace amounts of buclizine, a drug no longer in use in Australia, in another. Other issues include the undeclared presence of stimulants such as caffeine, synephrine or ephedrine. DNA data highlighted potential allergy concerns (nuts, wheat), presence of potential toxins (Neem oil) and animal ingredients (reindeer, frog, shrew), and possible substitution of bird cartilage in place of shark. Only 21% of the tested products were able to have at least one ingredient corroborated by DNA sequencing. This study demonstrates that, despite current monitoring approaches, contaminated and adulterated products are still reaching the consumer. We suggest that a better solution is stronger pre-market evaluation, using techniques such as that outlined in this study
On the connection between the intergalactic medium and galaxies: the H I–galaxy cross-correlation at z ≲ 1
We present a new optical spectroscopic survey of 1777 ‘star-forming’ (‘SF’) and 366 ‘non-star-forming’ (‘non-SF’) galaxies at redshifts z ∼ 0-1 (2143 in total), 22 AGN and 423 stars, observed by instruments such as the Deep Imaging Multi-Object Spectrograph, the Visible Multi-Object Spectrograph and the Gemini Multi-Object Spectrograph, in three fields containing five quasi-stellar objects (QSOs) with Hubble Space Telescope (HST) ultraviolet spectroscopy. We also present a new spectroscopic survey of 173 ‘strong’ (1014 ≤ NHI≲ 1017 cm−2) and 496 ‘weak’ (1013 ≲ NHI 50 per cent of ‘weak’ H i systems reside within galaxy voids (hence not correlated with galaxies), and are confined in dark matter haloes of masses smaller than those hosting ‘strong’ systems and/or galaxies. We speculate that H i systems within galaxy voids might still be evolving in the linear regime even at scales ≲2 Mpc
Perceptions and experiences of environmental health risks among new mothers: a qualitative study in
Toxicological screening and DNA sequencing detects contamination and adulteration in regulated herbal medicines and supplements for diet, weight loss and cardiovascular health
Use of herbal medicines and supplements by consumers to prevent or treat disease, particularly chronic conditions continues to grow, leading to increased awareness of the minimal regulation standards in many countries. Fraudulent, adulterated and contaminated herbal and traditional medicines and dietary supplements are a risk to consumer health, with adverse effects and events including overdose, drug-herb interactions and hospitalisation. The scope of the risk has been difficult to determine, prompting calls for new approaches, such as the combination of DNA metabarcoding and mass spectrometry used in this study. Here we show that nearly 50% of products tested had contamination issues, in terms of DNA, chemical composition or both. Two samples were clear cases of pharmaceutical adulteration, including a combination of paracetamol and chlorpheniramine in one product and trace amounts of buclizine, a drug no longer in use in Australia, in another. Other issues include the undeclared presence of stimulants such as caffeine, synephrine or ephedrine. DNA data highlighted potential allergy concerns (nuts, wheat), presence of potential toxins (Neem oil) and animal ingredients (reindeer, frog, shrew), and possible substitution of bird cartilage in place of shark. Only 21% of the tested products were able to have at least one ingredient corroborated by DNA sequencing. This study demonstrates that, despite current monitoring approaches, contaminated and adulterated products are still reaching the consumer. We suggest that a better solution is stronger pre-market evaluation, using techniques such as that outlined in this study
Dissipation of vibration in rough contact
The relationship which links the normal vibration occurring during the sliding of rough surfaces and the nominal contact area is investigated. Two regimes are found. In the first one, the vibrational level does not depend on the contact area, while in the second one, it is propor- tional to the contact area. A theoretical model is proposed. It is based on the assumption that the vibrational level results from a competition between two processes of vibration damping, the internal damping of the material and the contact damping occurring at the interface
Gas Accretion via Lyman Limit Systems
In cosmological simulations, a large fraction of the partial Lyman limit
systems (pLLSs; 16<log N(HI)<17.2) and LLSs (17.2log N(HI)<19) probes
large-scale flows in and out of galaxies through their circumgalactic medium
(CGM). The overall low metallicity of the cold gaseous streams feeding galaxies
seen in these simulations is the key to differentiating them from metal rich
gas that is either outflowing or being recycled. In recent years, several
groups have empirically determined an entirely new wealth of information on the
pLLSs and LLSs over a wide range of redshifts. A major focus of the recent
research has been to empirically determine the metallicity distribution of the
gas probed by pLLSs and LLSs in sizable and representative samples at both low
(z2) redshifts. Here I discuss unambiguous evidence for
metal-poor gas at all z probed by the pLLSs and LLSs. At z<1, all the pLLSs and
LLSs so far studied are located in the CGM of galaxies with projected distances
<100-200 kpc. Regardless of the exact origin of the low-metallicity pLLSs/LLSs,
there is a significant mass of cool, dense, low-metallicity gas in the CGM that
may be available as fuel for continuing star formation in galaxies over cosmic
time. As such, the metal-poor pLLSs and LLSs are currently among the best
observational evidence of cold, metal-poor gas accretion onto galaxies.Comment: Invited review to appear in Gas Accretion onto Galaxies, Astrophysics
and Space Science Library, eds. A. J. Fox & R. Dav\'e, to be published by
Springe
Time variation of the fine structure constant in the early universe and the Bekenstein model
We calculate bounds on the variation of the fine structure constant at the
time of primordial nucleosynthesis and at the time of neutral hydrogen
formation. We use these bounds and other bounds from the late universe to test
Bekenstein model. We modify the Kawano code, CAMB and CosmoMC in order to
include the possible variation of the fine structure constant. We use
observational primordial abundances of \De, \He and \Li, recent data from
the Cosmic Microwave Background and the 2dFGRS power spectrum, to obtain bounds
on the variation of . We calculate a piecewise solution to the scalar
field equation of Bekenstein model in two different regimes; i) matter and
radiation, ii) matter and cosmological constant. We match both solutions with
appropriate boundary conditions. We perform a statistical analysis using the
bounds obtained from the early universe and other bounds from the late universe
to constrain the free parameters of the model. Results are consistent with no
variation of in the early universe. Limits on are
inconsistent with the scale length of the theory being larger than Planck
scale. In order to fit all observational and experimental data, the assumption
implied in Bekenstein's model has to be relaxed.Comment: 13 pages, 8 figures,version accepted to be published in Astronomy and
Astrophysic
Gas Accretion in Star-Forming Galaxies
Cold-mode gas accretion onto galaxies is a direct prediction of LCDM
simulations and provides galaxies with fuel that allows them to continue to
form stars over the lifetime of the Universe. Given its dramatic influence on a
galaxy's gas reservoir, gas accretion has to be largely responsible for how
galaxies form and evolve. Therefore, given the importance of gas accretion, it
is necessary to observe and quantify how these gas flows affect galaxy
evolution. However, observational data have yet to conclusively show that gas
accretion ubiquitously occurs at any epoch. Directly detecting gas accretion is
a challenging endeavor and we now have obtained a significant amount of
observational evidence to support it. This chapter reviews the current
observational evidence of gas accretion onto star-forming galaxies.Comment: Invited review to appear in Gas Accretion onto Galaxies, Astrophysics
and Space Science Library, eds. A. J. Fox & R. Dav\'e, to be published by
Springer. This chapter includes 22 pages with 7 Figure
An Introduction to Gas Accretion onto Galaxies
Evidence for gas accretion onto galaxies can be found throughout the
universe. In this chapter, I summarize the direct and indirect signatures of
this process and discuss the primary sources. The evidence for gas accretion
includes the star formation rates and metallicities of galaxies, the evolution
of the cold gas content of the universe with time, numerous indirect indicators
for individual galaxies, and a few direct detections of inflow. The primary
sources of gas accretion are the intergalactic medium, satellite gas and
feedback material. There is support for each of these sources from observations
and simulations, but the methods with which the fuel ultimately settles in to
form stars remain murky.Comment: 14 pages, 5 figures, Invited review to appear in Gas Accretion onto
Galaxies, Astrophysics and Space Science Library, eds. A. J. Fox & R. Dav\'e,
to be published by Springe
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