Statoliths of the whelk Buccinum undatum Hollyman, P. R.; Leng, M. J.; Chenery, S. R. N. ...
Marine ecology. Progress series (Halstenbek),
06/2018, Letnik:
598
Journal Article
Recenzirano
Odprti dostop
Sustainability within the fisheries of the commercially important European whelk Buccinum undatum has become a major concern because of over-exploitation and increased landings in many European ...coastal shelf seas due to the expansion of export markets to East Asian countries. Current management of B. undatum populations is difficult to achieve as several life history traits are problematic to accurately monitor. The current method of age determination for stock assessment has a low success rate and focuses on the use of putative annual rings on the surface of the organic operculum. Here, we validate an annual periodicity of growth ring formation in B. undatum statoliths that provides an alternative, reliable and accurate method for determining a whelk’s age. Laboratory-reared juvenile B. undatum of known provenance and age deposited a hatching ring at the time of emergence from their egg capsule and a clearly defined growth ring during February of their first and second years. Stable oxygen isotope profiles from the shells of 2 adult whelks confirmed annual growth ring deposition by demonstrating seasonal cycles of δ18O in the shell that matched the relative position and number of visible growth rings in the statolith. Validation of annually resolved statolith growth rings will, for the first time, provide fisheries scientists with a tool to determine the age structure of B. undatum populations and allow analytical stock assessments that will enable informed decisions for future management practices of whelk fisheries.
Electrical grid voltage sags are a significant industrial power quality concern. According to a survey result across the US, voltage sags and short-duration power outages are responsible for 92% of ...power quality problems faced by industrial customers. These power interruptions often impose severe cost penalties in plant shutdowns for many industries. A series compensation scheme for an induction motor is presented with inherent voltage sag ride through capability. The system utilizes a system of three-phase floating capacitor H-bridge converters located in each phase between the utility grid and a squirrel-cage induction motor. By injecting a series voltage in each phase, the proposed system can manipulate the voltage supplied to a motor, increasing its tolerance of grid voltage sags. The voltage injection scheme has an inherently leading grid power factor under steady state and, hence, generates VARs into the grid, over a wide range of load conditions. The paper develops mathematical analysis of the proposed system to quantify both the voltage sag ride-through and the reactive power generation that results. The analysis shows that voltage sag tolerance of the proposed system is closely related to the motor fundamental power factor. Moreover, it is found that unity power factor operation of the system, as seen from the grid, is possible and that the reactive power generation capability can also be accurately quantified. A 5-hp experimental testbed is used to validate both the grid voltage ride-through capability feature and the reactive power generation characteristics.
Health literacy refers to acquiring and utilizing health information to make health-related actions and decisions. Filipino domestic workers with low health literacy are often vulnerable to health ...problems due to poor living and working conditions.
This study examined the effect of an online health literacy promotion program on health literacy and health knowledge of Filipino domestic workers in Macao.
The mixed method combined quantitative findings of a quasi-experimental study with qualitative results applied. The quasi-experiment included three parallel groups: a synchronous online education group (videoconference group), an asynchronous online education group (video group), and a control group. A total of 88 Filipino domestic workers were assigned to one of these groups, and eight respondents participated in two focus-group interviews respectively after the intervention.
For quantitative data, both synchronous and asynchronous online education interventions had positive effects. While comparing with the control group, participants in the videoconference group were more likely to have better health promotion health literacy after the intervention (β = 5.36,
= .02), and participants in the video group were more likely to have better general health literacy (β = 5.17,
= .01), disease prevention health literacy (β = 5.31,
= .04), health promotion health literacy (β = 5.97,
= .01). For qualitative data, three themes and eight subthemes were extracted after the online health literacy promotion program. After integrating the findings of this study, the study found that this program was essential and beneficial for Filipino domestic workers' health knowledge and health literacy.
Overall, online health literacy promotion programe had positive impacts on participants revealed in this study. Asynchronous online education has made significant progress in overall health literacy, which may be more suitable as a widely promoted education method because of the characteristics and working conditions of this population.
An application of H-bridges that enable soft start and power factor correction of cage induction machines is presented. The proposed power electronics employs floating capacitor H-bridges connected ...in series with utility grid and a cage induction motor to provide series voltage compensation. Injecting a series voltage in each phase, the proposed system can be used to control the motor voltage during starting and hence limit the motor starting current. In addition, an algorithm is proposed to accurately predict the worst case scenario for bridge dc capacitor voltage before motor starting. Thus, a dc capacitor overvoltage problem can be avoided. Experimental results show that the proposed system can successfully soft start a standard squirrel cage induction machine under different modes and load conditions. A simple representation of the worst case scenario for dc capacitor voltage before motor starting is established.
Abstract
Calculating age and growth rate for the commercially important whelk, Buccinum undatum in the aid of fishery management has historically been undertaken using growth rings on the organic ...operculum. This is difficult due to their poor readability and confusion between two different sets of growth lines present. Recent work presented the calcium carbonate statolith as an alternative for age determination of B. undatum. Here we compare the use of statoliths and opercula, comparing their readability and creating growth curves for three distinct populations across the United Kingdom. Using these data, we also test the most appropriate growth equation to model this species. Lastly, we use oxygen isotope analysis of the shells to assign accurate ages to several individuals from each site. These data were used to test the accuracy of statolith and operculum ages. Statoliths, whilst more time consuming to process have improved clarity and accuracy compared with the opercula. This improved readability has highlighted that a Gompertz growth function should be used for populations of this species, when in past studies, von Bertalanffy is often used. Statoliths are a viable improvement to opercula when assessing B. undatum in the context of fishery monitoring and management.
Three-phase floating H-bridges can be inserted between the utility grid and an induction motor to inject a voltage in series with the grid voltage. The magnitude and phase of this voltage is used to ...control the motor voltage under steady-state operation so as to lower the motor power losses over its entire load range. This is made possible because the three-phase H-bridge can be used to both increase and decrease the motor voltage relative to the grid voltage as required. This feature affects the performance of the overall system, more specifically, the motor power conversion efficiency is improved, lowering its operating temperature and, hence, improving reliability and lifetime expectancy. A variety of motor voltage control options exist, the controller presented is suitable for applications using loads such as fans and pumps, where variable frequency is not required. Readily available machine nameplate data are used to identify the motor output power associated with its maximum efficiency operating point when operated under rated voltage. This data are then used as the basis to control the motor voltage according to the square root of the measured motor input power. The controller and the performance of the three-phase H-bridge are described. The benefits of the variable voltage control are assessed by comparing the motor performance with the machine operated at its rated voltage. The chosen controller also results in the H-bridge dc voltages being relatively low and constant over a wide load range, hence lowering the power losses and electrical stress in the power electronics. Both experimental results and theoretical predictions are used to illustrate the performance of both the three-phase H-bridge and the motor.
Genetic and epigenetic defects in Wnt/β-catenin signaling play important roles in colorectal cancer progression. Here we identify
DACT3, a member of the DACT (Dpr/Frodo) gene family, as a negative ...regulator of Wnt/β-catenin signaling that is transcriptionally repressed in colorectal cancer. Unlike other Wnt signaling inhibitors that are silenced by DNA methylation,
DACT3 repression is associated with bivalent histone modifications. Remarkably,
DACT3 expression can be robustly derepressed by a pharmacological combination that simultaneously targets both histone methylation and deacetylation, leading to strong inhibition of Dishevelled (Dvl)-mediated Wnt/β-catenin signaling and massive apoptosis of colorectal cancer cells. Our study identifies
DACT3 as an important regulator of Wnt/β-catenin signaling in colorectal cancer and suggests a potential strategy for therapeutic control of Wnt/β-catenin signaling in colorectal cancer.
Chlorophyll and xanthophyll dyes extracted from a single source of filamentous freshwater green algae (Cladophora sp.) were used to sensitize dye sensitized solar cells and their performances were ...investigated. A more positive interaction is expected as the derived dyes come from a single natural source because they work mutually in nature. Cell sensitized with mixed chlorophyll and xanthophyll showed synergistic activity with improved cell performance of 1.5- to 2-fold higher than that sensitized with any individual dye. The effect of temperature and the stability of these dyes were also investigated. Xanthophyll dye was found to be more stable compared to chlorophyll that is attributed in the ability of xanthophyll to dissipate extra energy via reversible structural changes. Mixing the dyes resulted to an increase in effective electron life time and reduced the process of electron recombination during solar cell operation, hence exhibiting a synergistic effect.
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