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51.
Individuals of species that change sex from male to female may gain a “size advantage” from that sex change; that is, as males
become larger, they become female, thus increasing their fecundity with their size. However, males could also gain an early
and different reproductive size advantage by choosing large females as mates. While male preference for large females has
been observed in many dioecious species, we know little about male size preference in sex-changing species. In choice experiments,
we examined whether males of two congeneric species of marine sex-changing snails, Crepidula fornicata and C. convexa, chose large females over small ones as partners. We also used choice tests to see whether males of C. fornicata, a species whose members form long-term, multi-animal stacks, would choose two females in a stack over a single female. Surprisingly,
males of neither species showed a preference for large females, in spite of the documented fecundity advantage associated
with large female-size. Males of C. fornicata chose slightly, but not significantly, more single females than stacks, suggesting that neither number nor size drives mate
choice in these animals. Key factors that may influence this lack of size preference include long association time, the likelihood
of sperm competition, and the cost of extended mate search; it may also be that sex-change itself, the very factor that creates
female-biased sexual size dimorphism in these species, prevents size preference, as males may gain sufficient reproductive
advantage from eventually becoming large females themselves to offset any benefit of choosing large females. 相似文献
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Ferrero Pablo Attallah Olivia A. Valera Miguel Ángel Aleksic Ivana Azeem Muhammad Nikodinovic-Runic Jasmina Fournet Margaret Brennan 《Journal of Polymers and the Environment》2022,30(7):2837-2846
Journal of Polymers and the Environment - An energy-efficient high throughput pre-treatment of low-density polyethylene (LDPE) using a fast, reactive extrusion (REX) assisted oxidation technique... 相似文献
54.
Olea-Olea Selene Escolero Oscar Mahlknecht Jürgen Mona Jorge Ortega Lucia Beramendi-Orosco Laura Zamora-Martinez Olivia Tadeo-Leon Javier 《Environmental geochemistry and health》2022,44(7):2301-2323
Environmental Geochemistry and Health - The thermal mineral water of Peñón de los Baños spa (Mexico City) has been used for over 500 years starting in pre-Hispanic times and... 相似文献
55.
Baloch Qadar Bakhsh Maher Sourath Shah Syed Naseeb Sheeraz Muhammad Iqbal Nadeem Raza Hassan 《Environmental science and pollution research international》2022,29(55):83099-83111
Environmental Science and Pollution Research - The devastating effects of the COVID-19 pandemic have left many repercussions for the tourism industry to preempt any future catastrophe of this... 相似文献
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M.A. Hannan Maher Arebey R.A. Begum Hassan Basri 《Waste management (New York, N.Y.)》2012,32(12):2229-2238
An advanced image processing approach integrated with communication technologies and a camera for waste bin level detection has been presented. The proposed system is developed to address environmental concerns associated with waste bins and the variety of waste being disposed in them. A gray level aura matrix (GLAM) approach is proposed to extract the bin image texture. GLAM parameters, such as neighboring systems, are investigated to determine their optimal values. To evaluate the performance of the system, the extracted image is trained and tested using multi-layer perceptions (MLPs) and K-nearest neighbor (KNN) classifiers. The results have shown that the accuracy of bin level classification reach acceptable performance levels for class and grade classification with rates of 98.98% and 90.19% using the MLP classifier and 96.91% and 89.14% using the KNN classifier, respectively. The results demonstrated that the system performance is robust and can be applied to a variety of waste and waste bin level detection under various conditions. 相似文献
60.
John A. Simon Stew Abrams Tim Bradburne Dan Bryant Matthew Burns Daniel Cassidy John Cherry Sheau‐Yun Chiang Douglas Cox Michelle Crimi Elizabeth Denly Bill DiGuiseppi Jim Fenstermacher Stephanie Fiorenza Joseph Guarnaccia Nathan Hagelin Linda Hall John Hesemann Erika Houtz Stephen S. Koenigsberg Francois Lauzon Jeffrey Longsworth Tom Maher Angus McGrath Ravi Naidu Charles J. Newell Beth L. Parker Tadbir Singh Paul Tomiczek Rick Wice 《补救:环境净化治理成本、技术与工艺杂志》2019,29(4):31-48
Sixty leading members of the scientific, engineering, regulatory, and legal communities assembled for the PFAS Experts Symposium in Arlington, Virginia on May 20 and 21, 2019 to discuss issues related to per‐ and polyfluoroalkyl substances (PFAS) based on the quickly evolving developments of PFAS regulations, chemistry and analytics, transport and fate concepts, toxicology, and remediation technologies. The Symposium created a venue for experts with various specialized skills to provide opinions and trade perspectives on existing and new approaches to PFAS assessment and remediation in light of lessons learned managing other contaminants encountered over the past four decades. The following summarizes several consensus points developed as an outcome of the Symposium:
- Regulatory and policy issues: The response by many states and the US Environmental Protection Agency (USEPA) to media exposure and public pressure related to PFAS contamination is to relatively quickly initiate programs to regulate PFAS sites. This includes the USEPA establishing relatively low lifetime health advisory levels for PFAS in drinking water and even more stringent guidance and standards in several states. In addition, if PFAS are designated as hazardous substances at the federal level, as proposed by several Congressional bills, there could be wide‐reaching effects including listing of new Superfund sites solely for PFAS, application of stringent state standards, additional characterization and remediation at existing sites, reopening of closed sites, and cost renegotiation among PRPs.
- Chemistry and analytics: PFAS analysis is confounded by the lack of regulatory‐approved methods for most PFAS in water and all PFAS in solid media and air, interference with current water‐based analytical methods if samples contain high levels of suspended solids, and sample collection and analytical interference due to the presence of PFAS in common consumer products, sampling equipment, and laboratory materials.
- Toxicology and risk: Uncertainties remain related to human health and ecological effects for most PFAS; however, regulatory standards and guidance are being established incorporating safety factors that result in part per trillion (ppt) cleanup objectives. Given the thousands of PFAS that may be present in the environment, a more appropriate paradigm may be to develop toxicity criteria for groups of PFAS rather than individual PFAS.
- Transport and fate: The recalcitrance of many perfluoroalkyl compounds and the capability of some fluorotelomers to transform into perfluoroalkyl compounds complicate conceptual site models at many PFAS sites, particularly those involving complex mixtures, such as firefighting foams. Research is warranted to better understand the physicochemical properties and corresponding transport and fate of most PFAS, of branched and linear isomers of the same compounds, and of the interactions of PFAS with other co‐contaminants such as nonaqueous phase liquids. Many PFAS exhibit complex transport mechanisms, particularly at the air/water interface, and it is uncertain whether traditional transport principles apply to the ppt levels important to PFAS projects. Existing analytical methods are sufficient when combined with the many advances in site characterization techniques to move rapidly forward at selected sites to develop and test process‐based conceptual site models.
- Existing remediation technologies and research: Current technologies largely focus on separation (sorption, ion exchange, or sequestration). Due to diversity in PFAS properties, effective treatment will likely require treatment trains. Monitored natural attenuation will not likely involve destructive reactions, but be driven by processes such as matrix diffusion, sorption, dispersion, and dilution.