Geochemical zoning and early differentiation in the moon

The volatile elements (e.g., Rb, Pb, Tl, Bi, Cs) seem to have been depleted at the time of lunar accretion. Accordingly, it may be assumed that the moon initially accreted from refractory material. The good correlation between volatile/involatile element ratios (e.g., Cs/U, K/La, K/Zr) in both highland and maria samples means that element distribution in lunar crustal rocks is not governed by volatility differences. This and other evidence encourages the view that the moon was accreted homogeneously. A consequence of homogeneous accretion theories is that very efficient large-scale element fractionation is required to account both for the high near-surface concentrations of refractory elements (e.g., Th, U, REE, Zr, Ba, etc.) and for the Ca-Al-rich crust

A Qualitative Exploration of the Role of Vape Shop Environments in Supporting Smoking Abstinence

E-cigarettes are the most popular method of quitting smoking in England and most are purchased in specialist vape shops. This qualitative study explores how the vape shop environment is experienced by quitters to support smoking abstinence. Semi-structured qualitative interviews were conducted to elicit experiences of e-cigarette use, including experiences of vape shops, in 40 people who had used e-cigarettes in a quit attempt. Observations of six shops in a range of locations were also undertaken. Interview and observation data were analysed using inductive thematic analysis and triangulated. At an individual level, smoking abstinence was supported through shop assistants’ attempts to understand customers’ smoking preferences in order to: (i) tailor advice about the most appropriate product; and (ii) offer an ongoing point of contact for practical help. At an interpersonal level, shops offered opportunity to socialise and reinforce a vaping identity, although the environment was perceived as intimidating for some (e.g., new and female users). At a structural level, shops ensured easy access to products perceived to be good value by customers and had adapted to legislative changes. Vape shops can provide effective behavioural support to quitters to maintain smoking abstinence. Health professionals could capitalise on this through partnership working with shops, to ensure best outcomes for clients wanting to use e-cigarettes to quit smoking

Identification of Channel-lining Amino Acid Residues in the Hydrophobic Segment of Colicin Ia

Colicin Ia is a bactericidal protein of 626 amino acid residues that kills its target cell by forming a channel in the inner membrane; it can also form voltage-dependent channels in planar lipid bilayer membranes. The channel-forming activity resides in the carboxy-terminal domain of ∼177 residues. In the crystal structure of the water-soluble conformation, this domain consists of a bundle of 10 α-helices, with eight mostly amphipathic helices surrounding a hydrophobic helical hairpin (helices H8-H9). We wish to know how this structure changes to form a channel in a lipid bilayer. Although there is evidence that the open channel has four transmembrane segments (H8, H9, and parts of H1 and H6-H7), their arrangement relative to the pore is largely unknown. Given the lack of a detailed structural model, it is imperative to better characterize the channel-lining protein segments. Here, we focus on a segment of 44 residues (573–616), which in the crystal structure comprises the H8-H9 hairpin and flanking regions. We mutated each of these residues to a unique cysteine, added the mutant colicins to the cis side of planar bilayers to form channels, and determined whether sulfhydryl-specific methanethiosulfonate reagents could alter the conduction of ions through the open channel. We found a pattern of reactivity consistent with parts of H8 and H9 lining the channel as α-helices, albeit rather short ones for spanning a lipid bilayer (12 residues). The effects of the reactions on channel conductance and selectivity tend to be greater for residues near the amino terminus of H8 and the carboxy terminus of H9, with particularly large effects for G577C, T581C, and G609C, suggesting that these residues may occupy a relatively constricted region near the cis end of the channel

Resisting socioeconomic apartheid through tourism microentrepreneurship in Bahía de Banderas — Puerto Vallarta

Despite receiving harsh criticisms from academia, the model of enclave tourism continues to be widely implemented by transnational conglomerates. Accordingly, enclave mass tourism development, materialized in the form of all-inclusive, self-contained resorts, may create apparent socioeconomic apartheid at destinations, through removing locals from tourist spaces where host-guest exchanges are most likely to occur. However, preliminary results from a qualitative study being conducted in Bahía de Banderas — Puerto Vallarta, Mexico, suggest that despite adverse conditions, microentrepreneurs are still able to glean some economic opportunities. Microentrepreneurs must be extremely judicious in how they choose to take advantage of available opportunities; there seems to be a thin line between moderate success on the one hand and total failure on the other, with immediate repercussions in their livelihoods

What is the value of peer involvement in advancing tobacco harm reduction?

E-cigarettes are considered a disruptive technology [1], evidencing rapid growth in the financial market and attracting a distinct new customer base of would-be quitters, especially in Great Britain and the USA. Where use is permitted, and regulation is favourable to users [2], e-cigarettes have become the most popular method of smoking cessation [3] and for many are a long-term alternative to smoking [4]. Outside of a medical lens, vaping can be recreational, not just a smoking cessation aid [5]. Simply trying vaping has, for many, had the happy side effect of encouraging smoking cessation through a non-medicalised route. Despite the lack of early research endorsement and the absence of health messaging on e-cigarette use, smokers experimented with them anyway, with many making the switch and quitting smoking completely of their own accord. As the evidence supporting their use as a reduced risk product and a substitute for smoking grew, so too have the endorsements, such that the UK now leads the way in a ‘cautiously permissive’ stance towards the use of e-cigarettes [6, 7]

Mammographic density and its interaction with other breast cancer risk factors in an Asian population

10.1038/sj.bjc.6606085British Journal of Cancer1045871-874BJCA

Sizing the Protein Translocation Pathway of Colicin Ia Channels

The bacterial toxin colicin Ia forms voltage-gated channels in planar lipid bilayers. The toxin consists of three domains, with the carboxy-terminal domain (C-domain) responsible for channel formation. The C-domain contributes four membrane-spanning segments and a 68-residue translocated segment to the open channel, whereas the upstream domains and the amino-terminal end of the C-domain stay on the cis side of the membrane. The isolated C-domain, lacking the two upstream domains, also forms channels; however, the amino terminus and one of the normally membrane-spanning segments can move across the membrane. (This can be observed as a drop in single-channel conductance.) In longer carboxy-terminal fragments of colicin Ia that include ≤169 residues upstream from the C-domain, the entire upstream region is translocated. Presumably, a portion of the C-domain creates a pathway for the polar upstream region to move through the membrane. To determine the size of this translocation pathway, we have attached “molecular stoppers,” small disulfide-bonded polypeptides, to the amino terminus of the C-domain, and determined whether they could be translocated. We have found that the translocation rate is strongly voltage dependent, and that at voltages ≥90 mV, even a 26-Å stopper is translocated. Upon reduction of their disulfide bonds, all of the stoppers are easily translocated, indicating that it is the folded structure, rather than some aspect of the primary sequence, that slows translocation of the stoppers. Thus, the pathway for translocation is ≥26 Å in diameter, or can stretch to this value. This is large enough for an α-helical hairpin to fit through