6,592 research outputs found
Description of early life history stages of the northern sculpin (Icelinus borealis Gilbert) (Teleostei: Cottidae)
Larvae of the genus Icelinus are collected more frequently
than any other sculpin larvae in ichthyoplankton surveys in the Gulf of Alaska and Bering Sea, and larvae of the northern sculpin (Icelinus borealis) are commonly found in the ichthyofauna in both regions. Northern sculpin are geographically isolated north of the Aleutian Islands,
Alaska, which allows for a definitive description of its early life history development in the Bering Sea. A
combination of morphological characters, pigmentation, preopercular spine pattern, meristic counts, and squamation in later developmental stages is essential to identify Icelinus to the species level. Larvae of northern sculpin have 35â36 myomeres, pelvic fins with one spine and two
rays, a bony preopercular shelf, four preopercular spines, 3â14 irregular postanal ventral melanophores, few, if any, melanophores ventrally on the gut, and in larger specimens, two rows of ctenoid scales directly beneath the dorsal fins extending onto the caudal peduncle. The taxonomic characters of the larvae of northern sculpin in this study may help differentiate northern sculpin larvae from its congeners, and other sympatric sculpin larvae, and further aid in solving complex systematic relationships within the
family Cottidae
Hybrid HVDC for supply of power to offshore oil platforms
A HVDC hybrid system, comprising a line commutated thyristor HVDC converter and a STATCOM, is proposed in this paper for supplying power to offshore oil platforms that do not have their own generation. The proposed system combines the robust performance, low capital cost and low power loss of a line commutated HVDC converter, with the fast dynamic performance of an equivalent VSC Transmission system. The paper describes the principles and control strategies of the proposed system. PSCAD/EMTDC simulations are presented to demonstrate the robust performance of the system using case studies of various operating conditions such as black-start, load perturbations, AC fault conditions and disturbance caused by the starting of large local induction machines
Yoga use, physical and mental health, and quality of life in adults with irritable bowel syndrome: A mixed-methods study
Introduction
Intervention studies show yoga has several physical and psychological benefits for Irritable Bowel Syndrome (IBS), however few studies have explored yoga use in everyday life amongst people with IBS. This study explored yoga use as a predictor of IBS-related quality of life (QoL) in relation to other physical and psychological factors. It also utilized the Capability, Opportunity, Motivation-Behaviour (COM-B) model to investigate predictors of yoga practice, with a qualitative exploration of perceived IBS-related benefits and barriers to yoga.
Methods
A cross-sectional, mixed-methods survey was used. 219 adults with IBS (86.3% female, 32% yoga practitioners, mean age 46.42 years) completed a questionnaire battery to assess symptom severity, psychological symptoms, general health, QoL, COM-B constructs in relation to yoga, and perceived effectiveness of yoga for IBS. Open-ended responses assessing perceptions of yoga in relation to IBS were analysed using thematic analysis.
Results
In hierarchical linear regression, education, yoga use, symptom severity, anxiety, depression, and general health explained 64.6% of variance in QoL (p<.001). Yoga use explained 6.1% after controlling for education. In hierarchical logistic regression, COM-B constructs explained 37.5% of the variance in yoga use (p<.001). In the final model, only Opportunity (p<.05) and Motivation (p<.001) significantly predicted yoga practice. Qualitative analysis identified three themes reflecting perceived benefits of yoga (IBS Relief, A Valuable Self-Management Tool, Holistic Wellbeing), and three reflecting perceived barriers/limitations (Lack of Physical Capability, Need for a Tailored Approach, Limited Motivation).
Conclusion
This study identifies significant relationships between yoga use in everyday life, physical and mental health, and IBS-related QoL, and identifies the COM-B model as a useful framework for understanding yoga practice amongst people with IBS. The findings demonstrate that practicing yoga as part of daily life may positively impact both physical and mental health of IBS patients. Furthermore, the findings can be used to inform more targeted yoga interventions and increase accessibility of yoga for this group
Parental feeding behaviour and motivations regarding pre-school age children: a thematic synthesis of qualitative studies
Poor childhood diet is a major risk factor for disease and obesity, and parents of pre-school children are in a powerful position to influence diet for life. The technique of thematic synthesis (Thomas & Harden, 2008) was used to synthesise recent qualitative research on parental feeding of pre-school age children (18 months â 6 years). The aim was to inform development of nutrition advice by gaining a comprehensive picture of parental feeding behaviours and motivations. Six key parental feeding behaviours were identified: modelling, rewards, pressure and encouragement, repeated exposure, creativity, and limiting intake. Four overarching themes regarding motivations were identified: promoting good health (balance and variety, and weight control); building positive relationships (child involvement, and parental engagement and responsiveness); practicalities and constraints (time, cost, and lack of culinary skill, and pressure and flexibility); and emotional motivations (problem avoidance, and emotional investment). Practicalities and constraints, and emotional motivations impacted more significantly on low income parents. In order to be effective, nutrition advice ought to tap into parentsâ strong desire to build positive relationships and promote good health while remaining sensitive to the significant constraints and practicalities faced
Universality in Three-Frequency Resonances
We investigate the hierarchical structure of three-frequency resonances in
nonlinear dynamical systems with three interacting frequencies. We hypothesize
an ordering of these resonances based on a generalization of the Farey tree
organization from two frequencies to three. In experiments and numerical
simulations we demonstrate that our hypothesis describes the hierarchies of
three-frequency resonances in representative dynamical systems. We conjecture
that this organization may be universal across a large class of three-frequency
systems
Geographical Change in Religious Denomination Affiliation in Mississippi, 1970-2000
The religious landscape of Mississippi has long been dominated by evangelical Protestant denominations, most prominently the Southern Baptist and United Methodist. These two denominations have led the state in total number of churches and church members since the early 20th century, with few affiliations contending for their numbers. However, as the aggregate population of the state increases for the first time since the 1930?s, these traditional denominational patterns have been subjected to shifts in demographic conditions occurring throughout the state. To evaluate the impacts of demographic changes on traditional geographic religious patterns, an evaluation comparing religious and demographic variables for 1970, 1980, 1990, and 2000 was completed. Results of this evaluation indicated changes in Mississippi?s patterns of denominational affiliation, with the dominating Southern Baptist, United Methodist, and Presbyterian affiliations experiencing losses in church adherent percentages, and increased church adherent growth in Pentecostal, Latter Day Saints, and Church of Christ affiliations
Three-frequency resonances in dynamical systems
We investigate numerically and experimentally dynamical systems having three
interacting frequencies: a discrete mapping (a circle map), an exactly solvable
model (a system of coupled ordinary differential equations), and an
experimental device (an electronic oscillator). We compare the hierarchies of
three-frequency resonances we find in each of these systems. All three show
similar qualitative behaviour, suggesting the existence of generic features in
the parameter-space organization of three-frequency resonances.Comment: See home page http://lec.ugr.es/~julya
Effect of Larval Nutrition on Maternal mRNA Contribution to the Drosophila Egg.
Embryonic development begins under the control of maternal gene products, mRNAs and proteins that the mother deposits into the egg; the zygotic genome is activated some time later. Maternal control of early development is conserved across metazoans. Gene products contributed by mothers are critical to many early developmental processes, and set up trajectories for the rest of development. Maternal deposition of these factors is an often-overlooked aspect of parental investment. If the mother experiences challenging environmental conditions, such as poor nutrition, previous studies in Drosophila melanogaster have demonstrated a plastic response wherein these mothers may produce larger eggs to buffer the offspring against the same difficult environment. This additional investment can produce offspring that are more fit in the challenging environment. With this study, we ask whether D. melanogaster mothers who experience poor nutrition during their own development change their gene product contribution to the egg. We perform mRNA-Seq on eggs at a stage where all mRNAs are maternally derived, from mothers with different degrees of nutritional limitation. We find that nutritional limitation produces similar transcript changes at all degrees of limitation tested. Genes that have lower transcript abundance in nutritionally limited mothers are those involved in translation, which is likely one of the most energetically costly processes occurring in the early embryo. We find an increase in transcripts for transport and localization of macromolecules, and for the electron transport chain. The eggs produced by nutrition-limited mothers show a plastic response in mRNA deposition, which may better prepare the future embryo for development in a nutrition-limited environment
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