Effects of Electronic Cigarette Liquid Solvents Propylene Glycol and Vegetable Glycerin on User Nicotine Delivery, Heart Rate, Subjective Effects, and Puff Topography

Electronic cigarettes (ECIGs) are a class of tobacco products that use a heating element to aerosolize a liquid, typically containing nicotine, allowing for user inhalation. Despite their rapid growth in popularity, little is known about ECIGs including how certain device and liquid factors influence nicotine delivery, user physiological and subjective responses, and puffing behavior (puff topography). Limited pre-clinical research has demonstrated that the ratio of two solvents commonly found in ECIG liquids, propylene glycol (PG) and vegetable glycerin (VG), may have an influence on the nicotine content of ECIG aerosols. However, the extent to which PG:VG ratio in ECIG liquids influences acute effects experienced by ECIG users is unknown. The primary purpose of this clinical laboratory study was to examine the influence of PG:VG ratio on plasma nicotine concentration, heart rate (HR), subjective effects, and puff topography in experienced ECIG users. Thirty ECIG-experienced individuals participated in four independent laboratory conditions that differed only by the PG:VG ratio in the ECIG liquid (100:0, 55:45, 20:80, and 2:98). In each condition, participants used a 3.3 volt “eGo” ECIG battery attached to a 1.5 Ohm dual coil “cartomizer” loaded with 1 ml of ECIG liquid (nicotine concentration: 18 mg/ml). Participants completed two ECIG use bouts (10 puffs with 30 sec inter-puff-interval) in each study condition. ECIG PG:VG ratio had a direct influence on nicotine delivery, subjective effects, and puff topography. Nicotine delivery and overall nicotine intake were highest following the use of the liquids containing mostly PG, despite participants taking significantly shorter and smaller puffs in these conditions, suggesting PG may be a more efficient nicotine-delivery vehicle than VG. Abstinence symptoms were suppressed similarly across all PG:VG ratios, and HR also increased in a similar fashion in all conditions following ECIG use. Participants reported significantly lower scores on items assessing sensory ECIG effects following use of the 100PG:0VG liquid, indicating a lower overall satisfaction with this liquid. Further evaluating the influence of PG and VG and other ECIG device and liquid characteristics on ECIG acute effects using clinical laboratory methodologies could inform regulations of these products

Letter from J. F. Spindle to T. B. and Emma Larimore

Letter from J. F. Spindle to T. B. and Emma Larimore. The two-page handwritten correspondence is dated 22 November 1912. There is a transcript of the note in the item PDF

Comparison of curricula in Canadian and American secondary schools

Thesis (Ed.M.)--Boston University, 1935. This item was digitized by the Internet Archive

Realism, Natural Kinds, and Attention Deficit Hyperactivity Disorder

Realism about mental disorders is a perennial area of dispute, but the controversy burns especially intensely for Attention Deficit Hyperactivity Disorder (ADHD). In this dissertation, I clarify what is at issue in these debates, surveying how realists have typically argued for mental disorder realism: the definitional debate about health and illness. I argue that the realist need not be committed to the terms of the definitional debate and recommend that a better approach is to show that mental disorders are natural kinds. While there are many accounts of kind-hood on offer, I adopt Richard Boyd’s homeostatic property cluster (HPC) theory of kinds, which I interpret through the philosophy of neuroscience literature on mechanisms. In sum, I conclude that if ADHD is a natural kind – and thus real – then individuals diagnosed with the disorder should be sufficiently similar with respect to an underlying cognitive neurobiological mechanism. To determine whether ADHD individuals are similar in this way, I consider the question through Russell Barkley’s Executive Function Model of ADHD. Relying primarily on the cognitive neurobiological research, I argue that there is now reasonable evidence to conclude that the DSM classification of ADHD corresponds not to a single natural kind, but several. Thus, ADHD is thus real

EXAMINATION OF ELECTRONIC CIGARETTE USER PUFF TOPOGRAPHY: THE EFFECT OF A MOUTHPIECE-BASED TOPOGRAPHY MEASUREMENT DEVICE ON PLASMA NICOTINE AND SUBJECTIVE EFFECTS

Electronic cigarettes (ECIGs) operate by heating a nicotine-containing solution resulting in an inhalable aerosol. Nicotine delivery may be affected by users’ puffing behavior (puff topography), and little is known about the puff topography of ECIG users. The purpose of this study was to examine the extent to which a mouthpiece-based topography measurement device influences the acute effects associated with ECIG use. Twenty-nine experienced ECIG users completed two sessions differing only by the presence of a mouthpiece-based topography recording device. In both sessions, participants completed one 10 puff, 30 sec inter-puff interval (IPI) ECIG-use bout and another 90 minute ad libitum bout. Acute ECIG effects (plasma nicotine concentration, heart rate [HR], and subjective effects) were largely unaffected by the presence of the topography recording device. Evaluating ECIG puff topography through clinical laboratory methodology is necessary to understand the effects of these products (including toxicant exposure) and to inform their regulation

Confocal Microscopy Study of the Embryonic Development of the Viviparous Nemertean Prosorhochmus americanus Reveals Larval Features Supporting Indirect Development In Hoplonemerteans

Recent studies of hoplonenemertean planuliform larvae have clarified their development and provided insight into larval evolution within the phylum. However, an assessment of viviparous development using modern techniques is lacking. To help facilitate a comprehensive comparative evaluation of developmental diversity within hoplonemerteans, we have conducted a confocal laser scanning microscopy investigation of the development in Prosorhochmus americanus, one of the few viviparous hoplonemertean species. Phalloidin staining provides evidence of a modified transitory larval epidermis, and reveals that the foregut, midgut, proboscis, central nervous system, and body wall musculature form early in development, consistent with observations for planktonic and encapsulated hoplonemertean larvae. However, invaginations characteristic of these larvae were not observed. Acetylated tubulin labeling and light microscopy shows that embryos are uniformly ciliated, and some specimens possess a caudal ciliary cirrus and/or apical tuft which are characteristic of planktonic larvae. These are interpreted as vestigial structures in the non-swimming P. americanus embryos. The findings provide additional evidence that hoplonemerteans exhibit a form of metamorphosis in their life history and thus exhibit indirect development. However, a comparative assessment of larval features in P. americanus suggests an evolutionary trend towards direct development in this species

The impact of group formation in a cooperative learning environment

Research indicates that cooperative learning (CL) has the potential to increase accounting student satisfaction without impairing the learning of technical material (Lancaster, K., & Strand, C. (2001). Using the team-learning model in a managerial accounting class: An experiment in cooperative learning. Issues in Accounting Education, 16(4), 549–567). This study investigates whether instruc- tor-formed heterogeneous groups produce a more effective CL environment than student self- selected groups by measuring individual academic performance and perceptions. Results indicate the presence of a treatment interaction, implying that the best group composition may not be the same for all students. In some circumstances, higher ability students had statistically higher perfor- mance in more homogeneous groups. Lower ability students did better (not significant) in heteroge- neous groupings. The majority of students gave high ratings to the impact of CL on learning and development of team skills. Students were only mildly interested in increasing the time spent in groups, indicating that they value both traditional teaching methods and CL