2,971 research outputs found
Plio-Quaternary exhumation history of the central Nepalese Himalaya: 1. Apatite and zircon fission track and apatite [U-Th]/He analyses
New apatite and zircon fission track and (U-Th)/He analyses serve to document the bedrock cooling history of the central Nepalese Himalaya near the Annapurna Range. We have obtained 82 apatite fission track (AFT), 7 zircon fission track (ZFT), and 7 apatite (U-Th)/He (AHe) ages from samples collected along the Marsyandi drainage, including eight vertical relief profiles from ridges on either side of the river averaging more than 2 km in elevation range. In addition, three profiles were sampled along ridge crests that also lie ∼2 km above the adjacent valleys, and a transect of >20 valley bottom samples spans from the Lesser Himalaya across the Greater Himalaya and into the Tethyan strata. As a consequence, these data provide one of the more comprehensive low-temperature thermochronologic studies within the Himalaya. Conversely, the youthfulness of this orogen is pushing the limits of these dating techniques. AFT ages range from >3.8 to 0 Ma, ZFT ages from 1.9 to 0.8 Ma, and AHe ages from 0.9 to 0.3 Ma. Most ridges have maximum ages of 1.3–0.8 Ma at 2 km above the valley bottom. Only one ridge crest (in the south central zone of the field area) yielded significantly older ZFT and AFT ages of ∼2 Ma; we infer that a splay of the Main Central Thrust separates this ridge from the rest of the Greater Himalaya. ZFT and AFT ages from a vertical transect along this ridge indicate exhumation rates of ∼1.5 km Myr−1 (r2 > 0.7) from ∼2 to 0.6–0.8 Ma, whereas AHe ages indicate a faster exhumation rate of ∼2.6 km Myr−1 (r2 = 0.9) over the last 0.8 Myr. Exhumation rates calculated for six of the remaining seven vertical profiles ranged from 1.5 to 12 km Myr−1 (all with low r2 values of <0.6) for the time period from ∼1.2 to 0.3 Ma, with no discernible patterns in south to north exhumation rates evident. The absence of a trend in exhumation rates, despite a strong spatial gradient in rainfall, argues against a correlation of long-term exhumation rates with modern patterns of rainfall. AFT ages in the Tethyan strata are, on average, older than in the Greater Himalaya and may be a response to a drier climate, slip on the South Tibetan Detachment, or a gentler dip of the underlying thrust ramp. These data are further evaluated with thermokinematic modeling in the companion paper by Whipp et al
Variation in the food intake of grass carp, Ctenopharyngodon idella (Val.), fed singly or in groups
Each animal may be assumed to possess a unique
combination of physiological traits (Bennett, 1987).
However, there is little information on thc effects of
interindividual variation in fish (Cui and Liu, 1990).
Individual differences in competitive ability, aggressiveness
and or size can lead to the establishment of
dominance hierarchies within groups of fish (Metcalfe,
1989; Metcalfe et al., 1989). The variation in
growth rates in groups of fish are rclated to dominance
hierarchies and preferential access to food
resources by dominant individuals (Jenkins, 1969;
Fausch, 1984; Koebele, 1985). Recently, radiography
has been used to measure individual consumption
rates for groups of salmonids and has demonstrated
considerable inter-individual variation in food intake
(Jobling et al., 1989; Carter et al., 1992a; McCarthy
et al., 1992). Two aims of this study were to use
radiography to examine the variation in the food
consumption rate of grass carp, Ctenopharyngodon
idellu (Val.), held together and to assess whcther variation
in growth rates could bc explained by variation
in consumption rates. A final aim of this study was
to compare the day to day variation in consumption
rates of grass carp held in a group to thosc held
individually, in terms of the individual meal share, in
order to examine the cffect of endogenous influences
on appetite
Phenotypic assortment in wild primate networks: implications for the dissemination of information.
Open Access article published under Creative Commons Attribution Licence.Final published version© The AuthorsElectronic supplementary material is available at http://dx.doi.org/10.1098/rsos.140444 or via
http://rsos.royalsocietypublishing.org.This paper is a publication of the ZSL Institute of Zoology’s Tsaobis Baboon Project.Individuals' access to social information can depend on their social network. Homophily-a preference to associate with similar phenotypes-may cause assortment within social networks that could preclude information transfer from individuals who generate information to those who would benefit from acquiring it. Thus, understanding phenotypic assortment may lead to a greater understanding of the factors that could limit the transfer of information between individuals. We tested whether there was assortment in wild baboon (Papio ursinus) networks, using data collected from two troops over 6 years for six phenotypic traits-boldness, age, dominance rank, sex and the propensity to generate/exploit information-using two methods for defining a connection between individuals-time spent in proximity and grooming. Our analysis indicated that assortment was more common in grooming than proximity networks. In general, there was homophily for boldness, age, rank and the propensity to both generate and exploit information, but heterophily for sex. However, there was considerable variability both between troops and years. The patterns of homophily we observed for these phenotypes may impede information transfer between them. However, the inconsistency in the strength of assortment between troops and years suggests that the limitations to information flow may be quite variable.Churchill College, University of CambridgeNatural Environment Research Council (NERC)Leakey FoundationAnimal Behavior Society (USA)International Primatological SocietyExplorers Fun
Reduced ventilation and enhanced magnitude of the deep Pacific carbon pool during the last glacial period
It has been proposed that the ventilation of the deep Pacific carbon pool was not significantly reduced during the last glacial period, posing a problem for canonical theories of glacial–interglacial CO2 change. However, using radiocarbon dates of marine tephra deposited off New Zealand, we show that deep- (>2000 m>2000 m) and shallow sub-surface ocean–atmosphere 14C age offsets (i.e. ‘reservoir-’ or ‘ventilation’ ages) in the southwest Pacific increased by ∼1089 and 337 yrs respectively, reaching ∼2689 and ∼1037 yrs during the late glacial. A comparison with other radiocarbon data from the southern high-latitudes suggests that broadly similar changes were experienced right across the Southern Ocean. If, like today, the Southern Ocean was the main source of water to the glacial ocean interior, these observations would imply a significant change in the global radiocarbon inventory during the last glacial period, possibly equivalent to an increase in the average radiocarbon age >2 km>2 km of ∼700 yrs∼700 yrs. Simple mass balance arguments and numerical model sensitivity tests suggest that such a change in the ocean's mean radiocarbon age would have had a major impact on the marine carbon inventory and atmospheric CO2, possibly accounting for nearly half of the glacial–interglacial CO2 change. If confirmed, these findings would underline the special role of high latitude shallow sub-surface mixing and air–sea gas exchange in regulating atmospheric CO2 during the late Pleistocene.This work was supported by the Royal Society, through a University Research Fellowship granted to LCS, and by NERC grant NE/L006421/1.This is the final published version. It first appeared at http://www.sciencedirect.com/science/article/pii/S0012821X1400716X#
From Anxiety to Confidence: Exploring the Measurement of Statistics Confidence and its Relationship with Experience, Knowledge and Competence within Psychology Undergraduate Students
© The Author(s) 2018. Psychology students often feel anxious about learning statistics, which can impact their performance. However, little research has explored statistics confidence, which may be an important way to reduce the negative connotations of associating statistics with anxiety. We aimed to explore whether modifying an existing measure of statistics anxiety (the STARS scale) and reframing the questions so students rated their confidence instead, would be associated with competence, prior knowledge and experience. A total of 104 undergraduate students completed an online questionnaire comprising these measures. The factor structure of the STARS scale was predominantly maintained when wording was changed to measure confidence instead of anxiety. Confidence was related to experience and competence, but not knowledge. Two aspects of confidence (interpretation of statistics and exam confidence) plus initial experiences were significant predictors of competence. Confidence was a mediator of the relationship between experience and competence. These findings suggest statistics confidence can be measured in a similar way to anxiety, and highlight areas that could be addressed to increase competence. Future research is needed to explore the relationship between statistics anxiety and statistics confidence, as well as to determine their individual impact on performance in assessments
Vertical Enhancement of Second-Year Psychology Research
Statistics and Research Methods modules are often unpopular with psychology students; however, at Oxford Brookes University the seminar component of the second-year research methods module tends to get very positive feedback. Over half of the seminars work towards the submission of a research-based experimental lab report. This article introduces and reflects on some of the recent changes made to improve this coursework by increasing the similarities with staff research; specifically targeting the areas of supervision, ethical review, peer review and dissemination. These developments are aligned with the teaching fellowship project, Vertical Enhancement of Statistics and Psychology Research, and aim to encourage second-year students to treat their group experiments as part of the department’s research activity, rather than simply as pieces of coursework. Enhancing this research-based aspect of the student experience teaching will hopefully, in turn, lead to higher quality third-year dissertations by increasing student enthusiasm for academic research
Helping students to climb the mountain: a study to inform the development of a resource to improve the learning of statistics in Psychology
Students often struggle with learning about statistics, which encompass a large proportion of a psychology degree. This pilot study explored how first- and final-year students reflected on their experiences of being taught this topic, in order to identify needs that could be addressed in a project to improve their learning. First-year students reported that they initially found their module challenging but that it became easier towards the end. Third year students recognised the importance of the topic but were not confident in their abilities. Most students reported anxiety about statistics. Although students were positive about practical classes, many felt that they could not easily remember the materials. The findings suggested three areas of focus to improve student learning. Firstly, diverse needs and levels of ability should be catered for. Secondly, students need help to go beyond surface learning and button clicking. Finally, low levels of engagement should be addressed. This work has informed a project to develop an online resource to address the above identified needs to enhance teaching of this important topic
Vandetanib-eluting radiopaque beads for chemoembolization: physicochemical evaluation and biological activity of vandetanib in hypoxia.
Vandetanib-eluting radiopaque beads (VERB) have been developed for use in transarterial chemoembolization of liver tumours, with the goal of combining embolization with local delivery of antiangiogenic therapy. The objective of this study was to investigate how embolization-induced hypoxia may affect antitumoural activity of vandetanib, an inhibitor of vascular endothelial growth factor receptor (VEGFR) and epidermal growth factor receptor (EGFR), in the context of hepatocellular carcinoma (HCC) treatment. We studied the effect of vandetanib on proliferation, cell cycle and apoptosis of HCC cells, in hypoxic conditions, as well as the direct effects of the beads on 3D HCC spheroids. Vandetanib suppressed proliferation and induced apoptosis of HCC cells in vitro and was equipotent in hypoxic and normoxic conditions. High degrees of apoptosis were observed among cell lines in which vandetanib suppressed ERK1/2 phosphorylation and upregulated the proapoptotic protein Bim, but this did not appear essential for vandetanib-induced cell death in all cell lines. Vandetanib also suppressed the hypoxia-induced secretion of VEGF from HCC cells and inhibited proliferation of endothelial cells. Incubation of tumour spheroids with VERB led to sustained growth inhibition equivalent to the effect of free drug. We conclude that vandetanib has both antiangiogenic and direct anticancer activity against HCC cells even in hypoxic conditions, warranting the further evaluation of VERB as novel anticancer agents
Increased entropy of signal transduction in the cancer metastasis phenotype
Studies into the statistical properties of biological networks have led to
important biological insights, such as the presence of hubs and hierarchical
modularity. There is also a growing interest in studying the statistical
properties of networks in the context of cancer genomics. However, relatively
little is known as to what network features differ between the cancer and
normal cell physiologies, or between different cancer cell phenotypes. Based on
the observation that frequent genomic alterations underlie a more aggressive
cancer phenotype, we asked if such an effect could be detectable as an increase
in the randomness of local gene expression patterns. Using a breast cancer gene
expression data set and a model network of protein interactions we derive
constrained weighted networks defined by a stochastic information flux matrix
reflecting expression correlations between interacting proteins. Based on this
stochastic matrix we propose and compute an entropy measure that quantifies the
degree of randomness in the local pattern of information flux around single
genes. By comparing the local entropies in the non-metastatic versus metastatic
breast cancer networks, we here show that breast cancers that metastasize are
characterised by a small yet significant increase in the degree of randomness
of local expression patterns. We validate this result in three additional
breast cancer expression data sets and demonstrate that local entropy better
characterises the metastatic phenotype than other non-entropy based measures.
We show that increases in entropy can be used to identify genes and signalling
pathways implicated in breast cancer metastasis. Further exploration of such
integrated cancer expression and protein interaction networks will therefore be
a fruitful endeavour.Comment: 5 figures, 2 Supplementary Figures and Table
Why do poor adults rate their oral health poorly?
The document attached has been archived with permission from the Australian Dental Association. An external link to the publisher’s copy is included.Background: The reasons why socioeconomic circumstances are associated with oral health are not well understood. This study investigated whether psychosocial factors might play an explanatory role. Methods: Cross-sectional survey data were used from the 1999 National Dental Telephone Interview Survey together with information from an accompanying questionnaire sent to adult interviewees. Household income and self-rated oral health were assessed with single items and life dissatisfaction, personal constraint and perceived stress were evaluated with standard psychometric scales. Bivariate associations were tested using chisquare and ANOVA and odds ratios estimated for low self-rated oral health using logistic regression. Results: Response to the questionnaire was 64.6 per cent and analysis was limited to dentate adults (n=3678). Low household income was positively associated with low self-rated oral health. Higher dissatisfaction with life, personal constraint and perceived stress scores were associated with low income and with low self-rated oral health. After adjusting for gender, age, income and missing teeth, adults with high personal constraint scores had greater odds of low self-rated oral health (OR 1.26; 1.10-1.43) as had adults with higher perceived stress scores (OR 1.69; 1.34-2.13). Conclusion: Psychosocial factors are important in understanding pathways between socioeconomic position and oral health status.A.E. Sanders and A.J. Spence
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