13,791 research outputs found

    The comparative genomics and complex population history of Papio baboons

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    What Are You Doing Now? Activity-Level Responses and Recall Failures in the American Time Use Survey

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    Questions about people's pasts are common in many surveys, but memories are error prone. The current research focuses on recall failures in the American Time Use Survey (ATUS). The ATUS most commonly encourages respondents to report all of their activities of the previous day in a forward chronological fashion, from the beginning to the end of the day. Even with a short reference period, the ATUS is prone to recall errors. We explore these errors, taking into account the response process, respondent, and interviewer as possible contributors to a recall failure. Importantly, we posit that the chronological recall of events leads to earlier activities affecting recall of the current activity. Events are more easily recalled when they are more distinct (less frequent) or additional contextual information about the event is available. While research has focused on these characteristics of the target event, the previous event recalled may also provide distinctiveness and context. Results suggest that periods following a more frequent activity are likely to be followed by a failure, although this is modulated by the duration of the event. The presence of others and the location of the event also have significant effects. The elapsed time since the event is also important, with a higher chance of recall failure for more distant activities. Although results highlight the importance of the response level in understanding outcomes, respondent characteristics still matter, as those with apparently lower cognitive ability are more likely to have a failure. Interviewers also contribute to the variance of recall failures, with interview experience not having an apparent effect, while interviewers who make other types of errors, surprisingly, show lower likelihoods of recall failure. The results shed light on the relationship between memory and survey errors and have implications for future survey design

    Validation of vapour / water production in a thermoelectric distillation system

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    In this study, mathematical calculations developed through water-vapour phase-change theory is used to interpret the processes involved in the fresh water production of a thermoelectric distillation system. The rate of water production depends on various parameters of vaporization phenomena such as water and vapour temperatures, pressure, specific volume, heat capacity and water-vapour surface area. The water-vapour surface area is constant 10 x 10 cm2, the initial depth of the sample water is 3 cm and the air occupies the 500 cm3 volume inside the chamber. The volume and the mass of vapour and water at water-vapour interface are calculated through one hour of the system operation. The temperatures of the system components, humidity and water production of the thermoelectric distillation system are measured. As a result, an increase in the temperature of water and hot side of the thermoelectric module leads to an increase in the water production by increasing the vapour formation at atmospheric pressure. After one hour of system operation, the water production reaches 34.5 mL and the humidity inside the chamber increases from 51 % to 74 %. The results also show the distillation ratio is 11.5%. The mathematical calculations validate the experimental data with reasonable agreement

    Tacit rejection of policy and teacher ambivalence – insights into English language teaching in Bahrain through actors’ perceptions

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    This article develops Phillips and Ochs's (2003) framework for policy borrowing, particularly their theorisations about indigenisation of international programmes. It uses the example of communicative language teaching (CLT) in Bahrain, exploring teacher perspectives regarding the effects of CLT on the preexisting arrangements in the national education system and the impact of contextual factors on the potential for CLT implementation. The author conducted qualitative focus groups with English language teachers in 10 schools. The analysis elucidates how teachers were tailoring their own ways through the new reforms to strike a satisfactory balance between the government's aims and the attitudes of the public. It answers the question, "What happens to English language teaching policy when it is transplanted to a different culture?" and concludes that it becomes actively rejected. The conclusion offers a conceptual development of Phillips and Ochs's framework, adding the option of rejection to the indigenisation stage. The article ends with some practical implications

    Dexamethasone treatment of pregnant F0 mice leads to parent of origin-specific changes in placental function of the F2 generation.

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    Dexamethasone treatment of F0 pregnant rodents alters F1 placental function and adult cardiometabolic phenotype. The adult phenotype is transmitted to the F2 generation without further intervention, but whether F2 placental function is altered by F0 dexamethasone treatment remains unknown. In the present study, F0 mice were untreated or received dexamethasone (0.2µgg(-1)day(-1), s.c.) over Days 11-15 or 14-18 of pregnancy (term Day 21). Depending on the period of F0 dexamethasone treatment, F1 offspring were lighter at birth or grew more slowly until weaning (P<0.05). Glucose tolerance (1gkg(-1), i.p.) of adult F1 males was abnormal. Mating F1 males exposed prenatally to dexamethasone with untreated females had no effect on F2 placental function on Day 19 of pregnancy. In contrast, when F1 females were mated with untreated males, F2 placental clearance of the amino acid analogue (14)C-methylaminoisobutyric acid was increased by 75% on Day 19 specifically in dams prenatally exposed to dexamethasone on Days 14-18 (P<0.05). Maternal plasma corticosterone was also increased, but F2 placental Slc38a4 expression was decreased in these dams (P<0.05). F0 dexamethasone treatment had no effect on F2 fetal or placental weights, regardless of lineage. Therefore, the effects of F0 dexamethasone exposure are transmitted intergenerationally to the F2 placenta via the maternal, but not paternal, line.This is the accepted manuscript. The final version is available at http://dx.doi.org/10.1071/RD14285

    Investigating the impact of nicotine on executive functions using a novel virtual reality assessment

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    Aims Nicotine is known to enhance aspects of cognitive functioning in abstinent smokers but the effects on specific areas of executive functions, and in non-smokers are inconclusive. This may be due in part to the poor sensitivity of tests used to assess executive functions. This study used a new virtual reality assessment of executive functions known as JEF (the Jansari assessment of Executive Functions) to address this issue. Design 2x2 design manipulating group (smokers and never-smokers) and drug (nicotine [4mg for smokers; 2mg for never smokers] vs placebo gum). Setting School of Psychology; University of East LondonParticipants 72 participants (aged 18 to 54). 36 minimally-deprived (2 hr) smokers and 36 never-smokers.Measurements Components of executive function were measured using the virtual reality paradigm JEF, which assesses eight cognitive constructs simultaneously as well as providing an overall performance measure. Results Univariate ANOVAs revealed that nicotine improved overall JEF performance, time-based prospective memory and event-based prospective memory in smokers (p < 0.01) but not in never-smokers. Action-based prospective memory was enhanced in both groups (p < 0.01) and never-smokers out-performed smokers on selective thinking and adaptive thinking (p < 0.01). Conclusions. Overall executive functioning and prospective memory can be enhanced by nicotine gum in abstinent smokers. That smokers were only minimally deprived suggests that JEFis a sensitive measure of executive functioning and that prospective memory is particularly susceptible to disruption by abstinence

    Catalysis by hen egg-white lysozyme proceeds via a covalent intermediate

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    Hen egg-white lysozyme (HEWL) was the first enzyme to have its three-dimensional structure determined by X-ray diffraction techniques(1). A catalytic mechanism, featuring a long-lived oxo-carbenium-ion intermediate, was proposed on the basis of model-building studies(2). The `Phillips' mechanism is widely held as the paradigm for the catalytic mechanism of beta -glycosidases that cleave glycosidic linkages with net retention of configuration of the anomeric centre. Studies with other retaining beta -glycosidases, however, provide strong evidence pointing to a common mechanism for these enzymes that involves a covalent glycosyl-enzyme intermediate, as previously postulated(3). Here we show, in three different cases using electrospray ionization mass spectrometry, a catalytically competent covalent glycosyl-enzyme intermediate during the catalytic cycle of HEWL. We also show the three-dimensional structure of this intermediate as determined by Xray diffraction. We formulate a general catalytic mechanism for all retaining beta -glycosidases that includes substrate distortion, formation of a covalent intermediate, and the electrophilic migration of C1 along the reaction coordinate

    Lack of correlation of stem cell markers in breast cancer stem cells

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    BACKGROUND: Various markers are used to identify the unique sub-population of breast cancer cells with stem cell properties. Whether these markers are expressed in all breast cancers, identify the same population of cells, or equate to therapeutic response is controversial. METHODS: We investigated the expression of multiple cancer stem cell markers in human breast cancer samples and cell lines in vitro and in vivo, comparing across and within samples and relating expression with growth and therapeutic response to doxorubicin, docetaxol and radiotherapy. RESULTS: CD24, CD44, ALDH and SOX2 expression, the ability to form mammospheres and side-population cells are variably present in human cancers and cell lines. Each marker identifies a unique rather than common population of cancer cells. In vivo, cells expressing these markers are not specifically localized to the presumptive stem cell niche at the tumour/stroma interface. Repeated therapy does not consistently enrich cells expressing these markers, although ER-negative cells accumulate. CONCLUSIONS: Commonly employed methods identify different cancer cell sub-populations with no consistent therapeutic implications, rather than a single population of cells. The relationships of breast cancer stem cells to clinical parameters will require identification of specific markers or panels for the individual cancer

    Comparison of DC Bead-irinotecan and DC Bead-topotecan drug eluting beads for use in locoregional drug delivery to treat pancreatic cancer

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    DC Bead is a drug delivery embolisation system that can be loaded with doxorubicin or irinotecan for the treatment of a variety of liver cancers. In this study we demonstrate that the topoisomerase I inhibitor topotecan hydrochloride can be successfully loaded into the DC Bead sulfonate-modified polyvinyl alcohol hydrogel matrix, resulting in a sustained-release drug eluting bead (DEBTOP) useful for therapeutic purposes. The in vitro drug loading capacity, elution characteristics and the effects on mechanical properties of the beads are described with reference to our previous work with irinotecan hydrochloride (DEBIRI). Results showed that drug loading was faster when the solution was agitated compared to static loading and a maximum loading of ca. 40–45 mg topotecan in 1 ml hydrated beads was achievable. Loading the drug into the beads altered the size, compressibility moduli and colour of the bead. Elution was shown to be reliant on the presence of ions to perform the necessary exchange with the electrostatically bound topotecan molecules. Topotecan was shown by MTS assay to have an IC50 for human pancreatic adenocarcinoma cells (PSN-1) of 0.22 and 0.27 lM compared to 28.1 and 19.2 lM for irinotecan at 48 and 72 h, respectively. The cytotoxic efficacy of DEBTOP on PSN-1 was compared to DEBIRI. DEPTOP loaded at 6 & 30 mg ml-1, like its free drug form, was shown to be more potent than DEBIRI of comparable doses at 24, 48 & 72 h using a slightly modified MTS assay. Using a PSN-1 mouse xenograft model, DEBIRI doses of 3.3–6.6 mg were shown to be well tolerated (even with repeat administration) and effective in reducing the tumour size. DEBTOP however, was lethal after 6 days at doses of 0.83–1.2 mg but demonstrated reasonable efficacy and tolerability (again with repeat injection possible) at 0.2–0.4 mg doses. Care must therefore be taken when selecting the dose of topotecan to be loaded into DC Bead given its greater potency and potential toxicity

    Second chances: Investigating athletes’ experiences of talent transfer

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    Talent transfer initiatives seek to transfer talented, mature individuals from one sport to another. Unfortunately talent transfer initiatives seem to lack an evidence-based direction and a rigorous exploration of the mechanisms underpinning the approach. The purpose of this exploratory study was to identify the factors which successfully transferring athletes cite as facilitative of talent transfer. In contrast to the anthropometric and performance variables that underpin current talent transfer initiatives, participants identified a range of psychobehavioral and environmental factors as key to successful transfer. We argue that further research into the mechanisms of talent transfer is needed in order to provide a strong evidence base for the methodologies employed in these initiatives
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